**Theoretical and Experimental Investigations of Dynamics of the Flexible Rotor with an Additional Active Magnetic Bearing**

Dorota Kozanecka

162 Performance Evaluation of Bearings

[8] Azukizawa T, Yamamoto S, Makino H (2009) Analysis of Dynamic Behavior of a

Magnetic Top Considering Aerodynamic Drag Force. LDIA2009

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/51113


**3. Results**

Temperature, relative humidity, and air velocity were determined to characterize the background environmental conditions of the prototyping room and the conditions near the 3D printer while it was printing, as shown in Table 2.

**Table 2.** Environmental characterization provided by the thermo-hygrometer: Air velocity, room temperature and relative humidity.

The CPC provided the particle number concentration, from 10 nm to >1000 nm, during the three tasks under study, in addition to the background measurement. Table 3 indicates the mean particle number concentration for these four distinct periods. Additionally, Figure 1 illustrates how the concentration of this airborne particle changed over time during the trial.

**Table 3.** Results provided by the CPC.

**Figure 1.** Number particle concentration (#/cm3) over time measured by the CPC.

The SMPS allowed us to better understand the potential exposure to smaller particles, by providing the size distributions from 10 to 420 nm. The corresponding results are presented in Table 4 and Figure 2.

**Table 4.** Results provided by the SMPS: Mean particle number concentration (particles/cm3) by particle size.

(1) Geometric Standard Deviation.

**Figure 2.** Results provided by the SMPS: Mean particle number concentration (particles/cm3) by particle size range.


**1. Introduction**

254 Antimicrobial Agents

White, T.J., Bruns, T.D., Lee, S. and Taylor, J.W. (1990). Amplification and direct sequencing

(Lauraceae). *Phytochemistry*. Vol. 66, pp. 2363-2367.

White). Academic Press, New York: 315-322.

from *Curvularia* sp., an endophytic fungus associated with *Ocotea corymbosa*

of fungal ribosomal RNA genes for phylogenetics. In: *PCR Protocols: A Guide to Methods and Applications* (eds. M.A. Innis, D.H. Gelfand, J.S. Sninsky and T.J.

> After the concept of selective toxicity in chemotherapy was introduced at the beginning of the 20th century, (Ehrlich, 1913), classes of substances with antibacterial properties, produced by microorganisms or created through synthesis were obtained. After the discovery of penicillin, the first antibiotic introduced in clinical use in man in 1940s, a large number of different types of antibiotics were produced. Antibiotics such as beta-lactams, macrolides, aminoglycozides and tetracyclines were discovered and introduced during an extremely short period. These were obtained either by isolation from fungi or by chemically modification of the naturally isolated substrates. These dominated the antimicrobial industry, while synthetically obtained substances only played a minor role. (Chu & Fernandes, 1991)

> In 1962, G. Y. Lesher and his collaborators introduced the first quinolone derivative, nalidixic acid **(**1-ethyl-1,4-dihydro-7-methyl-4-oxo-1,8-naphthyridine-3-carboxilyc acid), (1, Lesher et al. 1962) which had moderate activity against gram-negative organisms and was used for treating urinary tract infections. In the following years, a large gamma of derivatives from common elements were synthesized, which could be grouped by: cinoline (cinoxacin**),** pyrido-pyrimidine (pipemidic acid; piromidic acid), naphthyridine (nalidixic acid) and quinolones (oxolinic acid, miloxacin , tioxacin, etc.). These derivatives, with differentiated structures, have 2 common pharmacological properties, which allowed them to be classified as first generation biologically active derivatives with quinolone structure.

H S S

H2N

CH3

N

Gatifloxacin

N

COOH

COOH

BAY y 3118

O

NH2

N

F

The four generations have the following common aspects: an identical mechanism of action by inhibition the A subunit of DNA-gyrasa, an exclusively chromosomal bacteria resistance

> Cl N

Until now a large number of antibacterial substances belonging to the above mentioned class have been used in medicine.  Third- generation quinolones.

COOH

Moxifloxacin

Fig. 4. Fourth- generation quinolones.

F

N N

NH CH3

H2N

F

Trovafloxacin

H

H2N H F N

NH2

COOH

The success of first generation quinolones spurred the research in this area, which led to the obtainment through synthesis, after 1980, of a new series of compounds with stronger antibacterial properties and a broader spectrum of antibacterial activity which included gram positive and gram negative organisms, and which where defined by their ability to be applied on all localized infections. Koga and his collaborators introduced Norfloxacin into clinical use in 1980, the first quinolone with a fluorine atom substituted at the C-6 position and a piperazine C-7. Norfloxacin (Koga et al. 1980) was the first quinolone with increased antimicrobial activity, acting on a large spectrum of gram positive and gram negative microorganisms, including Pseudomonas aeruginosa.

Fig. 2. Second-generation quinolones.

Research in the field of derivatives with a quinolone structure have lead to new compounds obtained recently, which have been classified as third and fourth generation systemic quinolones, largely effective against Staphilococcus aureus. Their large antibacterial spectrum includes anaerobes, Chlamydia and Mycoplasma. (Brighty & Gootz, 2000)

N N

Piromidic Acid

The success of first generation quinolones spurred the research in this area, which led to the obtainment through synthesis, after 1980, of a new series of compounds with stronger antibacterial properties and a broader spectrum of antibacterial activity which included gram positive and gram negative organisms, and which where defined by their ability to be applied on all localized infections. Koga and his collaborators introduced Norfloxacin into clinical use in 1980, the first quinolone with a fluorine atom substituted at the C-6 position and a piperazine C-7. Norfloxacin (Koga et al. 1980) was the first quinolone with increased antimicrobial activity, acting on a large spectrum of gram positive and gram negative

N

C2H5

Pefloxacin

O

F N

N

N

O CH3

Ofloxacin

Research in the field of derivatives with a quinolone structure have lead to new compounds obtained recently, which have been classified as third and fourth generation systemic quinolones, largely effective against Staphilococcus aureus. Their large antibacterial

spectrum includes anaerobes, Chlamydia and Mycoplasma.  First-generation quinolones.

N

C2H5

Norfloxacin

N

Fleroxacin

Enoxacin

Fig. 2. Second-generation quinolones.

The four generations have the following common aspects: an identical mechanism of action by inhibition the A subunit of DNA-gyrasa, an exclusively chromosomal bacteria resistance and some similar bacteria effects: photo toxicity, neurotoxicity, cartilage toxicity.

Fig. 4. Fourth- generation quinolones.

Until now a large number of antibacterial substances belonging to the above mentioned class have been used in medicine. Quinolones are used when treating infections of the urinary tract, the respiratory tract, intestinal infections, ear/nose/throat infections, STD's, soft tissue and skin infections, meningitis caused by gram negative and Staphilococci bacteria, liver and bile infections, septicemia and endocarditis, prophylaxis and surgical infections and on patients with immune deficiencies.

Quinolones: Synthesis and Antibacterial Activity 259

Quinolone derivatives are an important class of antibacterial agents with wide action. Basic structure of these compounds (Figure 6) is a bicyclic structure, which contains a ring of type *A* 4-piridinona combined with aromatic or heteroaromatic ring *B.* The ring type *A* 4 piridinona is a ring with absolute necessity: an unsaturation in position 2-3, a free acid

**2. Quinolones: Structural features and method of synthesis**

function in position 3 and a substituent at nitrogen in position 1.

Z

6 7 8

Y

B A

5 4

X N

1 2 3

CO2H

O

R

The studies on quinolones indicated that in order for the compound to have antibacterial activity, the N-1 position requires a substituent. Many quinolones contain in N-position : ethyl (norfloxacin, pefloxacin, lomefloxacin) , fluoroethyl (fleroxacin), vinyl, clloroethyl, trifluoroethyl, aminoethyl,, cyclopropyl (ciprofloxacin), *t*-butyl, bicyclopentyl,*p*-

Quinolones contain at C-2 hydrogen (R2=H). The replacement at hydrogen has generally proven to be disadvantageous. However, some compounds containing a suitable C-1, C-2 ringhave recently been shown to possess biological activity. (Figure7 -Segawa 1992) (Figure

X N

3 5 4 6

R5

R6

R7

7 8 O

R1

1 2 CO2H

R2

**2.1 Structural features**

Fig. 6. Basic structure of quinolones.

fluorophenyl,2,4-difluorophenyl (Scott 1997)

Fig. 7. Basic structure of bicyclic quinolones.

**2.1.1 Bicyclic quinolones**

*Position 1*

*Position 2*

8 – Scott 1997)

The mechanism of action of quinolone antibacterial agents involves the inhibition of DNA gyrase (a bacterial topoisomerase II) resulting in a rapid bactericidal effect.

The antibacterial activity of quinolones (measured in terms of MIC), however, is the result of the combination of bacterial cell penetration and DNA gyrase inhibitory activity. The antibacterial activity of quinolones depends not only on the bicyclic heteroaromatic system combining the 1,4-dihydro-4-pyridine-3-carboxylic acid moiety and an aromatic ring, but also on the nature of the peripheral substituents and their spatial relationships. These substituents exert their influence on bacterial activity by providing additional affinity for bacterial enzimes, enhancing cell penetration or altering the pharmacokinetics.

The research for an ideal quinolone continues worldwide. Such a quinolone must be biologically active on a large spectrum of gram positive and gram negative bacteria, aerobes and anaerobes and mycobacteria, must have as few side effects as possible, excellent solubility in water and oral bioavailability.

In figure 5, the most common synthesized chemical variations obtained during the research for new quinolones with antibacterial activity, are visible.

Fig. 5. Structural variations of the most recent quinolones.


**Harmonics Generation, Propagation and Purging Techniques in Non-Linear Loads**

Hadeed Ahmed Sher, Khaled E. Addoweesh and Yasin Khan

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/53422


*Article* **Evaluating Targeted Intervention on Coal Miners' Unsafe Behavior**

### **Ruipeng Tong \*, Yanwei Zhang, Yunyun Yang, Qingli Jia, Xiaofei Ma and Guohua Shao**

School of emergency management and safety engineering, China University of Mining and Technology (Beijing), Beijing 100083, China<EMAIL_ADDRESS>(Y.Z<EMAIL_ADDRESS>(Y.Y<EMAIL_ADDRESS>(Q.J<EMAIL_ADDRESS>(X.M<EMAIL_ADDRESS>(G.S.) **\*** Correspondence<EMAIL_ADDRESS>Tel.: +86-137-1843-1777

Received: 25 December 2018; Accepted: 30 January 2019; Published: 1 February 2019

**Abstract:** Miners' unsafe behavior is the main cause of roof accidents in coal mines, and behavior intervention plays a significant role in reducing the occurrence of miners' unsafe behavior. However, traditional behavior intervention methods lack pertinence. In order to improve the intervention effect and reduce the occurrence of coal mine roof accidents more effectively, this study proposed a targeted intervention method for unsafe behavior. The process of targeted intervention node locating was constructed, and based on the analysis of 331 coal mine roof accidents in China, three kinds of targeted intervention nodes were located. The effectiveness of targeted intervention nodes was evaluated by using structural equation model (SEM) through randomly distributing questionnaires to miners of Pingdingshan coal. The results show that, in preventing roof accidents of coal mines, the targeted intervention nodes have a significant positive impact on the intervention effect. The method can also be applied to the safety management of other industries by adjusting the node location and evaluation process.

**Keywords:** unsafe behavior; targeted intervention; coal miners; safety management


**3. Oil wettability of shaft surfaces**

 Metal surfaces generally show good wettability with oils. Lubricating oil could spread easily into sliding area and stay there stably due to this property. This realizes good lubrication condition for machines.

There is a report that a low oil-wettable surface showed low friction due to the slip between the oil and the surface especially under fluid lubrication condition [9]. Some processing, coating, doping, etc., on the surface is usually necessary to provide low oil wettability to metal surfaces and needs additional cost. Recently, a novel grinding method was reported to give processed surface hydrophilicity [10], which probably could give low oil wettability to the surface at low cost. Though such techniques will possibly generalize low oil-wettable shafts, it seems that providing low oil wettability to the metal surfaces is not widely practiced so far to reduce the friction considering the benefits of good wettability to the lubricity described above and cost-effectiveness.

However, as will be shown below, imparting the low oil wettability to the shaft can be a relatively simple way to basically improve the lubrication condition for oil-impregnated sintered bearings.

### **4. Friction of oil-impregnated sintered bearings**

#### **4.1 Friction measurement for shafts with different wettability**

Friction coefficients of oil-impregnated sintered bearings with stainless steel shafts were measured. Specimens used are described in **Table 1**. The oilimpregnated sintered bearing used is commercially available mainly for OA equipment, and the size was relatively small.

**Table 1.**  *Specimen descriptions.*

 A simple test rig shown in **Figure 3** was used to measure the frictional torque of the bearings. The bearing was inserted and fixed in a ring-shaped weight. The frictional torque T was measured and converted to the friction coefficient μ by

$$
\mu\_- = \text{T/(RW)}\tag{1}
$$

where R is a radius of the bearing bore, and W is the weight load.

 Tests were conducted under a weight load of 6.7 N and at a shaft rotation speed of 100–800 rpm. Average frictional torque values were measured every 10 s for each 100-rpm increase in speed. Note that bearing frictional torque is usually different from that of the shaft.

 Two types of the shafts: noncoated and PTFE coated stainless steel shafts in **Table 1**, were evaluated. The noncoated stainless steel shafts were used for oil wettability shaft. For the low wettability shaft, PTFE (polytetrafluoroethylene) transfer film coated stainless steel shafts were used. The PTFE block was lightly pressed against the rotating shaft surface and then gently wiped with a nonwoven fabric to make a PTFE transfer coating. As PTFE is known for its low surface energy and ability to make a transfer film on the counter surface by sliding [11], the shaft surface made by this method was expected to have low oil wettability.

Surface roughness was not much different between the stainless steel shaft and the PTFE coated shaft surface as shown in **Table 1**. The shaft diameter measurement by a micrometer before and after application of the coating indicated the PTFE coating thickness was less than 1 μm, though exact thickness was unknown. The past literatures have showed the PTFE transfer film thickness was in the order of several nm [12–14].

 Oil droplets on the shafts about 10 s after being deposited there were shown in **Figure 4**. Colors of the droplets appeared a little different between the shafts, but it was due to the oil droplet thickness. Contact angle for noncoated shaft was much lower than that of the PTFE-coated shaft. The oil droplet on the noncoated shaft subsequently spread to cover the wide range of the shaft surface, while that on the PTFE-coated shaft retained its original droplet shape. This clearly indicates the lower oil wettability of the PTFE-coated shaft surface, as compared to that of the noncoated shaft surface.

**Figure 3.**  *Schematic view of bearing friction test rig.*

**Figure 4.**  *Oil droplets on the shafts.*

#### **Figure 5.**

*Friction coefficients of the bearings. Error bars indicate the standard error of the mean.*

**Figure 5** shows the friction coefficients of the bearings calculated by Eq. (1) with PTFE-coated and noncoated shafts. Error bars indicate the standard error of the means of five time test data for each shaft. The PTFE-coated shaft indicated a friction coefficient 20–50% lower than that of the noncoated shaft on average. Lubrication condition was presumed to be boundary lubrication, because friction coefficients are not largely dependent on shaft rotation speed.

**Figure 6** shows metallurgical microscopic (Olympus BHMJ, Japan) images of typical shaft and bearing surfaces before and after the tests. As compared to the intact shaft surface which could be estimated from the nonsliding area, wear marks were found on the sliding areas of shafts and bearings of both non- and PTFEcoated shaft tests. Comparing these surfaces, those for the PTFE-coated shaft test showed comparatively milder wear appearance.

### **4.2 Oil amount in the bearing clearance and the shaft wettability**

As was described, one of the big problems for the lubricity of oil-impregnated sintered bearings is poor oil supply to the sliding surfaces. We focused on the oil amount on the shaft and in the bearing clearance first as a cause of the friction reduction of the PTFE-coated shaft.

**Figure 7** shows oil deposition on the shafts pulled out from the bearings. Before the shafts were pulled out and the photos were taken, the shafts were rotated

**Figure 6.**

*Shaft and bearing surfaces before and after the tests. Upper: shaft surfaces. Lower: bearing surfaces.*

**Figure 7.**  *Oil deposition on the shafts.*

 several times by hand in the bearings. There were many oil droplets on the PTFEcoated shaft surface, while only interference patterns of a thin film of oil were found on the noncoated shaft surface, which suggested the richer oil amount for the PTFE-coated shaft and bearing pair. However, very thin oil film on the noncoated shaft might not have suggested the less oil amount directly, because it could be due to rapid oil spreading on the shaft before the photos were taken. Next, the oil in the bearing clearances was observed directly to clarify.

 The projections of the bearing clearances with fixed shafts were taken with a profile projector (Mitsutoyo PJ-3000F, Japan) and were shown in **Figure 8(a-1)** and **(b-1)**. The configuration of the projector and the tested bearing is shown in **Figure 9**.

The shafts were rotated by hand several times prior to the observation. Then the shafts were rotated about 45 degrees for several seconds from the initial positions. **Figure 8(a-2)** and **(b-2)** shows the photos at that time. Though clear individual figures of oil droplets were lacking, because they were deposited not only in the plane direction but also in the depth direction, there were many and large oil droplets indicated by arrows in the clearance between the PTFE-coated shaft and the bearing, while only a few and small droplets on the noncoated shaft. The difference between (a) and (b) in **Figure 7** must have been caused by this.

*On the Friction of Oil-Impregnated Sintered Bearings DOI: http://dx.doi.org/10.5772/intechopen.81757*

#### **Figure 8.**

*Bearing clearance projections. Arrows indicate the position of the droplets.*

In addition to the large amount of the oil droplets, droplets on the PTFE-coated shaft were observed to move together with shaft rotation, which leads to oil circulation in the clearance, from the moving images taken during the 45° shaft rotation.

**Figure 9.**  *Configuration of the projector and the tested bearing.*

New droplets were observed to emerge from the edge of the clearance and move in the same manner, that is, oil exudation in the clearance for the PTFE-coated shaft was clearly observed. No conspicuous motion of the oil droplets was observed in the clearance for the noncoated shaft during shaft rotation.

To summarize, much larger amount of oil was retained in the bearing clearance for the PTFE-coated shaft (i.e., low wettable shaft) than that for the noncoated shaft (i.e., highly wettable shaft), and oil circulation in the bearing clearance (along with shaft rotation) was observed for the PTFE-coated shaft. This means the oil-rich and secure oil exuding condition for the sliding area of the PTFE-coated shaft and relatively oil-poor condition for the noncoated shaft. Smaller friction of the PTFE-coated shaft was probably attributable to this oilrich condition.

The past literature has showed that the oil-poor condition increases the friction of sintered bearings [15]. More frequent solid–solid contact could occur for a less amount of oil condition in the sliding area, and thus was naturally one of the reasons for larger friction of the noncoated shaft. The oil-richer condition leads to the lower friction of the PTFE-coated shaft.

### **4.3 Other effects to cause the difference in friction**

In this section, possible mechanisms other than those mentioned in the previous section that caused the difference in friction are discussed.

One of the effects to be noticed especially for poor oil condition is capillary force. Less amount of oil supply to the sliding area would pose synergistic effect of poor lubricity and capillary force on friction increase to the bearing.

**Figure 10** shows the diagram of the oil meniscuses in the bearing clearance. Capillary force (F) is generated by negative Laplace pressure in the oil film. Assume that the oil filled the clearance plane symmetrically. Ignoring the effects of hydrodynamic force, the bearing end effect and oil droplets in the rest of the bearing clearance, and approximating zero contact angles between the oil and bearing/shaft

**Figure 10.**  *Diagram of oil meniscuses in bearing clearance.*

*On the Friction of Oil-Impregnated Sintered Bearings DOI: http://dx.doi.org/10.5772/intechopen.81757*

**Figure 11.**  *Calculated capillary force.*

surface (the curvature of the meniscus to be −h/2), the capillary force could be estimated as follows:

$$\mathbf{F} \equiv \mathbf{ZLB\Delta p} = -\mathbf{2LB\gamma}/(\mathbf{h}/\mathbf{2})\tag{2}$$

$$\mathbf{h} \approx \mathbf{c}(\mathbf{1} - \mathbf{e}\cos\theta) \tag{3}$$

$$\mathbf{L} \quad = \begin{array}{c} \mathbf{R}\sin\Theta \end{array} \tag{4}$$

where, B is the bearing width, Δp is the Laplace pressure, γ is the surface tension of the oil, c is the bearing radial clearance, ε is the eccentricity ratio, and R is the shaft radius.

**Figure 11** shows the calculated capillary force along with ε = 1 (which denotes the contact of the shaft and the bearing), c = 6.5 μm, and the tested bearing dimensions. |F| increases with a decrease in θ continuously and increases rapidly at an angle of 10° or less. **Figure 11** indicates that smaller the oil amount is, larger the capillary force becomes and consequently friction becomes larger.

To estimate the effect of the capillary force on the bearing friction, assume the oil filled by θ = ±30° for the noncoated shaft and θ = ±80° for the PTFEcoated shaft in the bearing clearance, respectively. Using Eqs. (2)–(4), F is −0.34 N for θ = ±30° and −0.11 N for θ = ±80°. Thus, the sum of the loads by weight (6.7 N) and capillary force, the actual load, for the PTFE-coated shaft, is 3% less than that of the noncoated shaft. Considering that friction reduction rate was 20–50%, this load difference would not be negligible. In considering a smaller θ, |F| increases rapidly and the actual load for a noncoated bearing becomes large. Hence, the capillary force due to less oil could be the part of the larger friction.

 Another possible mechanism of lower friction for the PTFE-coated shaft was slippage between the oil film and the shaft surface. A hydrophobic surface may cause boundary slip—a measure of relative fluid velocity at the solid-fluid interface [9, 16, 17] that leads to low friction under boundary lubrication. This effect was examined by the following friction tests.

The tests were conducted by using a ball-on-plate reciprocating friction tester for PTFE-coated and noncoated plates in the same oil as impregnated oil. **Table 2**

#### **Table 2.**

*Test conditions and materials for ball-on-plate tests.*

indicates the test materials and conditions. JIS SUS 304 stainless steel was used for the test material instead of JIS SUS 420J2 stainless steel (the shaft material) due to its easy preparation. JIS SUS 304 stainless steel was verified in advance to have as large oil wettability as JIS SUS 420J2 stainless steel by measuring the contact angles of the oil. The smallest load (1.6 N) the tester used could make was chosen to prevent the solid-solid contact as much as possible.

 **Figure 12** shows the time evolution of the friction coefficient of the initial four reciprocations for the PTFE-coated and noncoated plates. A negative friction coefficient denotes the reverse sliding direction. Both shafts showed the friction coefficient of about 0.08 which were comparable to that of noncoated shaft shown in **Figure 5**. This means that the lubrication condition of the ball-on-plate tests was probably about the same as that of the bearing test of the noncoated shaft and the PTFE-coating showed no particular effect like oil-surface slippage on friction under such lubrication condition.

For testing the solid-lubricity of the PTFE-coated shaft under dry condition, "dried" bearing was made by ultrasonic cleaning of oil-impregnated sintered bearing in acetone for more than 10 minutes and tested by the test rig of **Figure 3**. Both noncoated and PTFE-coated shaft indicated the friction coefficient of 0.2–0.3 which means PTFE-coating had little effect on friction reduction under dry condition. From these results, the lubricity of the PTFE coating was presumed not to contribute to the friction reduction in the bearing test.

#### **4.4 Mechanism to retain the oil droplets in the bearing clearance**

 In this section, the mechanism that caused the difference in oil amount in the bearing clearance will be discussed. Oil droplets in the bearing clearance will be modeled as micro-liquid bridges between slightly tilted plates. This modeling is appropriate because the angle between the shaft and bearing surfaces is usually very small.

**Figure 12.**  *Friction coefficient of ball-on-plate tests.*

*On the Friction of Oil-Impregnated Sintered Bearings DOI: http://dx.doi.org/10.5772/intechopen.81757*

**Figure 13.**  *Liquid bridge between tilted plates.*

**Figure 13** illustrates the drum-formed liquid bridge between tilted plates. The meniscus radius r in **Figure 13** is expressed by Eq. (5) when the radius of the drum (liquid bridge thickness) is much larger than that of the meniscus and the effect of gravity is ignorable [18].

$$\mathbf{r} \approx -\mathbf{\gamma}/\Delta \mathbf{p} \tag{5}$$

r is constant for a certain liquid bridge and the following relation holds geometrically:

$$\mathbf{H}/\mathbf{h} = \{\cos\phi\_1 + \cos\left(\phi\_2 + a\right) \} / \{\cos\psi\_1 + \cos\left(\psi\_2 - a\right) \} \\ = \mathbf{1} + \mathbf{x}\tan a \quad \text{(6)}$$

where x is the aspect ratio of the liquid bridge (thickness/height) assuming α is small. To satisfy this relation, contact angles have to vary according to the tilt angle and liquid bridge thickness.

The stability of liquid bridges between plates has been studied by several researchers [19–21]. According to these studies, the liquid bridge between parallel plates with a fixed contact angle between the liquid and the surface becomes unstable (which means a significant change of the liquid bridge in configuration and position) when one of the plates was tilted, even by a small amount [21]. This is because it is impossible to satisfy above relationship for the liquid-bridge with fixed contact angle.

Usually, contact angles could vary between receding and advancing contact angles, which is called contact angle hysteresis [22, 23], and the variable range depends on the liquid and surface material. According to the measuring method described in [22], the advancing angles were measured to be about 15 and 45°, and the receding angles were about 12 and 12.5° for noncoated and PTFE-coated plates, respectively. These results mean that contact angles could be in the following range: 12.5° ≦ φ1, φ2, ψ1, ψ2 ≦ 45° for the PTFE-coated plate.

 Assume that these contact angles could be applied to the liquid bridges. x = 3, φ1 = φ2 = 12°, and ψ1 = ψ2 = 15° for the noncoated plate combination according to the above measured values, then α ≈ 0.22° from Eq. (6). In the same way, for the PTFEcoated plate combination, x = 3, φ1 = φ2 = 12.5°, and ψ1 = ψ2 = 45°, then α ≈ 5.7°. For larger α, liquid bridges become unstable. To verify this calculation, liquid bridge behavior was observed between plates with a 0.5-mm gap. A photo example of the test configuration and a schematic of the tester were shown in **Figure 14**. The bright line and blue two spots on the liquid bridge were the reflection of background and illumination lamp. The plates are initially set in parallel, and then rotated around the bottom center of the liquid bridge in steps of 0.5°. As shown in the figure, x could be read about 3.

**Figure 14.**  *Example photo of liquid bridge test configuration and schematic of tester.*

For the noncoated upper and lower plate combination, the liquid bridge flowed in the narrower gap direction as soon as the tilt started. This means that the liquid bridge became unstable at a tilting angle less than 0.5°. For the PTFE-coated upper and lower plate combination, the liquid bridge flowed at tilting angles of 4~6.5° in several attempts. These results indicate that Eq. (6) is applicable for these conditions though Eq. (6) is not accurate, particularly when liquid bridge thickness is small, because the meniscus curve does not hold an arc shape but a more complex one (e.g., nodoid shape [20]).

We then applied Eq. (6) to the bearing clearance to estimate the possible maximum size of the oil droplet for the position in the clearance. The lower and upper plates can be considered to be the shaft and the bearing, respectively. The bearing surface has wettability similar to that of the noncoated shaft, which was roughly confirmed by oil droplet contact angle measurements. φ1 = φ2 = 12°, ψ1 = ψ2 = 15° for noncoated shaft and φ1 = 12°, φ2 = 12.5°, ψ1 = 15°, and ψ2 = 45° for PTFE-coated shaft, respectively, and tanα = dh/d(Rθ) were used for the calculation. **Figure 15** shows the calculated critical oil bridge thickness (xh), that is, the largest possible size of oil droplets in the bearing clearance.

From **Figure 15**, the PTFE-coated shaft indicated larger critical oil bridge thicknesses and could retain much larger oil droplets in the bearing clearance than those

**Figure 15.**  *Critical oil bridge thickness xh.*

#### *On the Friction of Oil-Impregnated Sintered Bearings DOI: http://dx.doi.org/10.5772/intechopen.81757*

for the noncoated shaft. This effect may yield the results shown in **Figures 6** and **7**  and lead to an oil-rich condition for the PTFE-coated shaft.

In addition to large oil droplets, clear movement of the oil droplets in the bearing clearance with shaft rotation was observed for the PTFE-coated shaft, as described in Section 4.2. This circulative movement in the clearance would induce the oil exudation from the bearing body probably contributing to large oil amount.

 To investigate the movement of the oil droplets, the dragging effect of the oil droplets by the PTFE-coated shaft was examined by simple tests shown in **Figure 16**. An oil droplet was bridged between the parallel plates with 1-mm gap, and the upper plate was moved in parallel to the lower plate. The plates were SUS304 stainless steel and the upper plate of **Figure 16(a-1)** and **(a-2)** was PTFE-coated. The upper plates moved to the right by a distance of about 3 mm from the position of **Figure 16(a-1)** and **(b-1)** to the position of **Figure 16(a-2)** and **(b-2)**, respectively.

As can be seen from **Figure 16**, the PTFE-coated plate dragged the oil droplet firmly while the bare stainless plate did a little.

**Figure 17** indicates the relationships between the upper plate travel distance and that of oil droplet. The oil droplet appears to stick to the PTFE-coated plate and to slip on the bare plate. This property may have caused the oil droplet circulation in the bearing clearance for the PTFE-coated shaft.

These phenomena would be a matter of energy but could also be explained by contact angle hysteresis. When the plate began to move, the oil droplet had to be deformed to retain the adhesion and the contact angle changed. As allowable contact angle range for the bare plate was much smaller than that of the PTFE-coated

#### **Figure 16.**

*Photos of oil droplet dragging test. (a-1) PTFE coated upper plate, original position. (a-2) 3 mm moved position. (b-1) Bare plate, original position. (b-2) 3 mm moved position.*

**Figure 17.**  *Relationships between the upper plate travel distance and that of oil droplet.*

plate, the interface between the oil droplet and the bare plate became unstable faster and caused to slip.

## **5. Conclusions**

The oil-impregnated sintered bearing with PTFE-coated shaft showed lower friction than that with the noncoated (bare metal) shaft. The PTFE-coated shaft was found to retain a larger amount of oil droplets in the bearing clearance than the noncoated shaft and make secure oil circulation in the clearance. These effects would yield the oil-rich and better lubrication condition leading to lower friction of the PTFE-coated shaft.

The lower friction of the PTFE-coated shaft is attributed to the lower wettability to the impregnated oil than that of the noncoated shaft. Large contact angle hysteresis concomitantly with the low wettability makes it possible to retain larger oil droplets in the bearing clearance. The low wettable surface drags the oil droplets firmer than the high wettable surface, which generates the secure oil circulation in the bearing clearance for the PTFE-coated shaft.

Low wettability is often associated with a large contact angle hysteresis but probably it is not always the case. Therefore, note that probably the results of this study are not applicable to all kinds of low wettable shafts. The large contact angle hysteresis of the PTFE-coated shaft could also be caused by nonuniformity of the PTFE transfer film due to our rough production method [21].

 However, generally speaking, using low wettable shafts must be one of the effective means to improve the lubrication condition and reduce the friction of oil-impregnated sintered bearings, though PTFE transfer film coating, which we used as low wettable coating in this study, is not wear-resistant and not a proper material for practical uses.

#### **Acknowledgements**

I would like to thank Fumiaki Katagiri and Yuta Kawabe, the former students of Institute of Technologists, for their devoted effort to the experiments.

*On the Friction of Oil-Impregnated Sintered Bearings DOI: http://dx.doi.org/10.5772/intechopen.81757*


*Article* **Chinese Named Entity Recognition of Geological News Based on BERT Model**

**Chao Huang, Yuzhu Wang \*, Yuqing Yu, Yujia Hao, Yuebin Liu and Xiujian Zhao**

School of Information Engineering, China University of Geosciences, Beijing 100083, China<EMAIL_ADDRESS>(C.H<EMAIL_ADDRESS>(Y.Y<EMAIL_ADDRESS>(Y.H<EMAIL_ADDRESS>(Y.L<EMAIL_ADDRESS>(X.Z.)

**\*** Correspondence<EMAIL_ADDRESS>
**Abstract:** With the ongoing progress of geological survey work and the continuous accumulation of geological data, extracting accurate information from massive geological data has become increasingly difficult. To fully mine and utilize geological data, this study proposes a geological news named entity recognition (GNNER) method based on the bidirectional encoder representations from transformers (BERT) pre-trained language model. This solves the problems of traditional word vectors that are difficult to represent context semantics and the single extraction effect and can also help construct the knowledge graphs of geological news. First, the method uses the BERT pre-training model to embed words in the geological news text, and the dynamically obtained word vector is used as the model's input. Second, the word vector is sent to a bidirectional long short-term memory model for further training to obtain contextual features. Finally, the corresponding six entity types are extracted using conditional random field sequence decoding. Through experiments on the constructed Chinese geological news dataset, the average F1 score identified by the model is 0.839. The experimental results show that the model can better identify news entities in geological news.

**Keywords:** BERT; named entity recognition; geological news; CRF


**3. The types of fluids**

of Henle. Besides these mechanisms, the renin release is also controlled by renal sympa-

Renin as an enzyme will then catalyze the conversion of angiotensinogen, a large protein produced in the liver, to angiotensin I, a decapeptide. This is the rate-limiting step of the RAAS pathway (**Figure 3**). Angiotensin I has little biologic activity apart from being the precursor to angiotensin II. Its conversion to angiotensin II involves the removal of two amino acid moieties by the angiotensin-converting enzyme (ACE). ACE is primarily located in the

The ultimate objective of the RAAS, through the activities of angiotensin II and aldosterone as summarized in **Figure 3**, is the preservation of effective fluid volume and pressure. The RAAS demonstrates the strong interconnection between the body fluid and electrolytes in maintaining the fluid homeostasis. In the acute setting, this interconnection is very relevant given the frequent alterations of the electrolyte contents of the body in the acute phase of illness. The assessment of electrolytes in the acute patients should, therefore, be comprehensive and extend beyond the laboratory results. For example, the assessment should also consider the potential electrolyte losses from the gastrointestinal tract, a common organ affected in acute illnesses [7].

The classic microcirculation model, based on the semipermeability of the capillary and postcapillary venule walls, and the presence of hydrostatic and oncotic pressure gradients across these walls had for long described the flux of fluids and electrolytes between the plasma and the interstitial fluid [8, 9]. The identification of the endothelial glycocalyx layer, a web of membrane-bound glycoproteins and proteoglycans on the luminal side of endothelial cells, has now challenged the classic model [10, 11]. The colloid oncotic pressure from the sub-glycocalyx space is a key determinant of the trans-capillary flow. The disruption to the integrity of the glycocalyx layer, or the "leakiness," in a number of acute situations like sepsis [12], trauma, and postsurgery, has been attributed to the development of interstitial edema

pulmonary capillaries, but it is also found in the kidney epithelial cells.

thetic nerves and angiotensin II.

42 Essentials of Accident and Emergency Medicine

**2.3. The microcirculation model**

**Figure 3.** The renin-angiotensin II-aldosterone-system (RAAS).

The history of intravenous fluids began during the cholera pandemic in Europe in the 1830s. The success of Thomas Latta in using a saline solution to resuscitate dying cholera patients paved the way for the widespread use of intravenous fluids and the research to refine their contents [15]. The early milestones in intravenous fluid therapy included the first experiment with albumin in 1834 [16] and the attempt by Sydney Ringer to develop a physiological solution for cardiac contractility with his Ringer's solution in 1876 [17]. Ringer's solution was modified by Alexis Hartmann in 1932 by including lactate to help overcome the acidosis in dehydrated pediatric patients [18]. The gelatins and other solutions with larger molecules only broke into the scene during the Second World War [19], although the first study in humans was performed in 1915 [20]. It is interesting that the history behind the most common type of fluids used, the 0.9% saline, is unclear. The present-day 0.9% saline, often called the "normal saline," has far higher sodium and chloride concentrations than Latta's 1832 saline solution. The only possible connection to 0.9% saline in the history was the in vitro studies of Hamburger in the 1890s that described 0.9% NaCl as an "indifferent solution" in which erythrocytes were least likely to lyse [21, 22].

From the above breakthroughs, the science of intravenous fluids has grown progressively, especially in the last couple of decades. Whether medicine will find an answer to the ideal intravenous fluid will be debatable, but more evidence has emerged in the comparison between the different types of fluids available.

#### **3.1. Crystalloids**

Crystalloids are solutions containing salts in the form of electrolytes and small molecules. The composition of commonly available crystalloids is given in **Table 1**.

[33–35]. Among the explanations suggested for the higher AKI incidence with the chloride-rich fluids like saline is the renal vasoconstrictive response to the high chloride delivery to the macula densa of JGA, a mechanism similar to the regulatory tubuloglomerular feedback [36, 37]. Similar trends of results implicating saline with AKI have been repeated in large retrospective trials [38, 39]. However, the only three large randomized trials comparing saline with balanced solutions to date have shown inconsistent results. These cluster randomized trials either showed no difference in renal outcomes [40] or a significant increase in major adverse kidney events within 30 days in the saline group for both the intensive care and emergency department populations [41, 42].

While large multicenter randomized controlled trials are ongoing to provide stronger evidence on the issue of saline [43, 44], there has been a notable shift in clinical practice with an increasing use of the balanced solutions [45]. 0.9% saline, nonetheless, remains the fluid of choice for patients with metabolic acidosis, hyponatremia, and traumatic brain injury, the

Colloid solutions are characterized by the large molecules suspended in carrier solutions that would also contain electrolytes. The colloid osmotic pressure or oncotic pressure generated by these large molecules helps to retain fluid in the intravascular space longer. The composi-

The volume effect of colloid, when compared to crystalloid, has traditionally been thought to be at a 1:3 ratio. This gives colloid a perceived advantage in reducing the volume of fluid

HES: hydroxyethyl starch. Gelofusine®: B Braun, Melsungen, Germany; Albumex®: CSL Limited, Victoria, Australia;

Voluven®: Fresenius-Kabi, Bad Homburg, German. All concentrations in mmol/L; osmolality in mosmol/kg.

Sodium 140 154 140 48-100 154 Potassium 5 0 0 0 0 Chloride 100 125 128 19 154 Calcium 2.2 0 0 0 0 Magnesium 1 0 0 0 0 Bicarbonate 24 0 0 0 0 Lactate 1 0 0 0 0 Acetate 0 0 0 0 0 Malate 0 0 0 0 0 Octanoate 0 0 6.4 32 0 Real osmolality 287 271 260 130 298

**Plasma Gelofusine® Albumex®4 Albumex®20 Voluven® (HES 6%**

**130/0.4)**

Approach to Fluid Therapy in the Acute Setting http://dx.doi.org/10.5772/intechopen.74458 45

latter attributed to its relatively high osmolality.

tion of the commonly available colloids is in **Table 2**.

**Table 2.** The composition of commonly used colloids.

**3.2. Colloids**

Plasma-Lyte 148®: Baxter International, Deerfield, IL, USA; Sterofundin®: B Braun, Melsungen, Germany. All concentrations in mmol/L; osmolality in mosmol/kg.

**Table 1.** The composition of commonly used crystalloids.

Based on their differing compositions, crystalloids have been divided into saline solutions and balanced solutions. Saline solutions, chiefly the 0.9% NaCl solutions, are differentiated from the rest of crystalloids by their high contents of sodium and chloride. These concentrations of 150 mmol/L, especially for chloride, are much higher than the plasma concentrations. The 0.9% saline has thus been described as supra-physiological, and the name "normal saline" has been put to question [23, 24]. Balanced solutions, on the other hand, are other solutions like Hartmann's, Plasmalyte 148®, and Sterofundin® that contains more closely resemble human plasma concentrations. These solutions achieve lower sodium and chloride concentrations through the addition of other electrolytes and buffers like lactate and acetate.

The debate is ongoing as to which will be the better choice for the acute population of patients, saline or balanced solutions. While saline is cheap and is still the most commonly used crystalloid in the world, there are significant concerns with its effect on acid-base balance and kidney function. The high chloride contents of saline contribute to the hyperchloremic or strong ion acidosis [25–27], and this has been well shown in different studies in different acute populations [28–30]. Given that acidosis is a common biochemical presentation in the acute setting, such acidosis could confuse patients' assessment. This has made a case for suggesting balanced solutions as the fluid of choice, even when saline has always been the conventional prescription like in diabetic ketoacidosis [31, 32].

On the other hand, the potential risk of acute kidney injury (AKI) from the use of saline is a main research agenda. Changing the intravenous fluid practice from chloride-rich fluids (0.9% saline, 4% succinylated gelatin, or 4% albumin) to chloride-restrictive fluids (Hartmann's solution, Plasma-Lyte 148, and 20% albumin) had been shown to reduce the incidence of AKI in the intensive care and emergency department populations in a single-center, open label sequential trial [33–35]. Among the explanations suggested for the higher AKI incidence with the chloride-rich fluids like saline is the renal vasoconstrictive response to the high chloride delivery to the macula densa of JGA, a mechanism similar to the regulatory tubuloglomerular feedback [36, 37]. Similar trends of results implicating saline with AKI have been repeated in large retrospective trials [38, 39]. However, the only three large randomized trials comparing saline with balanced solutions to date have shown inconsistent results. These cluster randomized trials either showed no difference in renal outcomes [40] or a significant increase in major adverse kidney events within 30 days in the saline group for both the intensive care and emergency department populations [41, 42].

While large multicenter randomized controlled trials are ongoing to provide stronger evidence on the issue of saline [43, 44], there has been a notable shift in clinical practice with an increasing use of the balanced solutions [45]. 0.9% saline, nonetheless, remains the fluid of choice for patients with metabolic acidosis, hyponatremia, and traumatic brain injury, the latter attributed to its relatively high osmolality.

#### **3.2. Colloids**

Based on their differing compositions, crystalloids have been divided into saline solutions and balanced solutions. Saline solutions, chiefly the 0.9% NaCl solutions, are differentiated from the rest of crystalloids by their high contents of sodium and chloride. These concentrations of 150 mmol/L, especially for chloride, are much higher than the plasma concentrations. The 0.9% saline has thus been described as supra-physiological, and the name "normal saline" has been put to question [23, 24]. Balanced solutions, on the other hand, are other solutions like Hartmann's, Plasmalyte 148®, and Sterofundin® that contains more closely resemble human plasma concentrations. These solutions achieve lower sodium and chloride concentrations

Plasma-Lyte 148®: Baxter International, Deerfield, IL, USA; Sterofundin®: B Braun, Melsungen, Germany. All concen-

**Plasma 0.9% NaCl Hartmann's Plasmalyte 148® Sterofundin®**

Sodium 140 150 131 140 140 Potassium 5 0 5 5 4 Chloride 100 150 111 98 127 Calcium 2.2 0 2 0 2.5 Magnesium 1 0 1 1.5 1 Bicarbonate 24 0 0 0 0 Lactate 1 0 29 0 0 Acetate 0 0 0 27 24 Gluconate 0 0 0 23 0 Maleate 0 0 0 0 5 Real osmolality 287 286 254 273 287

The debate is ongoing as to which will be the better choice for the acute population of patients, saline or balanced solutions. While saline is cheap and is still the most commonly used crystalloid in the world, there are significant concerns with its effect on acid-base balance and kidney function. The high chloride contents of saline contribute to the hyperchloremic or strong ion acidosis [25–27], and this has been well shown in different studies in different acute populations [28–30]. Given that acidosis is a common biochemical presentation in the acute setting, such acidosis could confuse patients' assessment. This has made a case for suggesting balanced solutions as the fluid of choice, even when saline has always been the conventional

On the other hand, the potential risk of acute kidney injury (AKI) from the use of saline is a main research agenda. Changing the intravenous fluid practice from chloride-rich fluids (0.9% saline, 4% succinylated gelatin, or 4% albumin) to chloride-restrictive fluids (Hartmann's solution, Plasma-Lyte 148, and 20% albumin) had been shown to reduce the incidence of AKI in the intensive care and emergency department populations in a single-center, open label sequential trial

through the addition of other electrolytes and buffers like lactate and acetate.

prescription like in diabetic ketoacidosis [31, 32].

trations in mmol/L; osmolality in mosmol/kg.

44 Essentials of Accident and Emergency Medicine

**Table 1.** The composition of commonly used crystalloids.

Colloid solutions are characterized by the large molecules suspended in carrier solutions that would also contain electrolytes. The colloid osmotic pressure or oncotic pressure generated by these large molecules helps to retain fluid in the intravascular space longer. The composition of the commonly available colloids is in **Table 2**.

The volume effect of colloid, when compared to crystalloid, has traditionally been thought to be at a 1:3 ratio. This gives colloid a perceived advantage in reducing the volume of fluid

HES: hydroxyethyl starch. Gelofusine®: B Braun, Melsungen, Germany; Albumex®: CSL Limited, Victoria, Australia; Voluven®: Fresenius-Kabi, Bad Homburg, German. All concentrations in mmol/L; osmolality in mosmol/kg.

**Table 2.** The composition of commonly used colloids.

infused during resuscitation. However, data from recent large multicenter trials on the use of different types of colloids suggested a smaller colloid: crystalloid ratio, between 1:1.1 and 1:1.6 [46–49]. The finding of smaller volume effect advantage from colloid than previously thought adds to the predominant concern on the use of colloid—its effects on the kidney.

defined the fluid bolus therapy as delivery of more than 250 mL of either colloid or crystalloid fluid over less than 30 minutes, with crystalloids the most acceptable [61]. These numbers only reflect the majority views on the fluid challenge and must be interpreted in the context of the other aspects of an acute fluid strategy—the fluid responsiveness and the fluid balance.

Approach to Fluid Therapy in the Acute Setting http://dx.doi.org/10.5772/intechopen.74458 47

Clinical assessment is always an integral component of any fluid therapy approach. Identifying body volume repletion and the likelihood to respond to fluid resuscitation should begin with the background history and elicitation of signs of volume deficits, from the peripheral temperature gradient and capillary refill time [62] to the tachycardia, decreased mean arterial pressure, and oliguria. However, reliance on these clinical signs alone for assessment of volume status and responsiveness could be misleading [63–65]. For instance, an increase in the mean arterial pressure following a fluid challenge could be a result of the changes in the

Beyond clinical signs, the indices of fluid responsiveness—both static and dynamic—have been extensively studied. The static index of central venous pressure (CVP), arguably the most commonly used measure of fluid responsiveness, has long been shown to have no meaningful relationship to fluid volume and should be abandoned [66]. Similarly, the more invasive static index measurement of pulmonary artery occlusion pressure (PAOP) has its limitations and

The dynamic indices of fluid responsiveness work on the basis of inducing a change in preload and following up the effects on stroke volume and cardiac output [69]. There are different versions of these dynamic measurements with many evolving around the respiratory variation of hemodynamic indices. Examples include the pulse pressure variation (PPV), the pulse contour-derived stroke volume, the inferior vena cava (IVC) parameters assessed by ultrasonography, and the descending aortic blood flow assessed by esophageal Doppler [70–75]. There are, however, limitations to the observations of these respiratory variations. Some of these are of practical significance, like the need for tidal volumes of >7 ml/kg, the absence of

An approach to assessment of fluid responsiveness that is not affected by the practical ventilatory limitations above is the passive leg raising, PLR [76]. The postural change in PLR transfers around 300 mL of venous blood from the lower body to the heart. The advantage of this is it is an endogenous fluid challenge that is rapidly reversible [77]. To date, the PLR has been deemed as the most reliable measure of fluid responsiveness [78], although an increase in the

It is important to recognize that fluid responsiveness does not necessarily mean that fluid challenges must be given. It also does not mean that patients should be receiving fluid challenges until they are no longer fluid responsive. The hemodynamic benefits of the fluid boluses should be weighed against the risks of accumulating positive fluid balance, with a strong consideration of the use of vasopressors like noradrenaline to improve

arterial vascular tone rather than a true increase in cardiac output.

spontaneous ventilatory efforts, and the absence of arrhythmia.

intra-abdominal pressure or pain could give a false-negative result [79].

does not predict fluid responsiveness [67, 68].

**4.2. Fluid responsiveness**

organ perfusion [80].

Strong evidence emerged in the last decade demonstrating a significant association between the risk of renal dysfunction, measured as AKI, and the need for renal replacement therapy, with the use of hydroxyethyl starch in the acute population of sepsis and intensive care [46, 47]. There are also doubts from observational data on the renal safety of another choice of colloid, the gelatins, in the septic population [50, 51]. The hyperoncotic albumin solutions (20–25%), on the other hand, have been associated with increased risk of renal events when used in cardiac surgery [52] and in patients in shock [53].

Besides these renal effects, colloids are more expensive than crystalloids, and there has been an absence of their clinical superiority over crystalloids in the mortality outcome of studies on different acute populations [49, 54, 55]. All these lead to the call for caution in the use of colloids. The recent Surviving Sepsis Guidelines, for example, strongly recommend against the use of hydroxyethyl starches and place albumin and gelatins as a second choice to crystalloids in sepsis fluid resuscitation [56].


2. Intestinal microbiota in wild birds

The majority of information regarding enteropathogens in wild birds has been ascertained by applying traditional microbiological techniques [10–12]. Research on the fecal flora of wild birds in a few well-studied species has focused on the prevalence of enteropathogenic bacteria that are most likely zoonotic. Representative species that are often found in diseased wild birds include Salmonella enterica serotypes Typhimurium and Enteritidis, Escherichia coli, Campylobacter jejuni, Pseudomonas aeruginosa, Pasteurella multocida, Clostridium botulinum, and Listeria monocytogenes. The carrier birds are often diverse species, including house sparrows, brown-headed cowbirds, white-throated sparrows, tufted ducks, crows, pheasants, pigeons, hook-bills, finches, free-living flamingos, quails, pheasants, red grouse, and waterfowl [1, 6, 8].

Many classical methods such as microscopy, culture, or serology have been used to detect and isolate pathogenic protozoa or fungi from excreta of migratory birds. Candida albicans and Candida tropicalis, which can become pathogenic in immunocompromised individuals, have been isolated from excreta of migratory gulls and geese [13]. Toxoplasma gondii has been isolated from many migratory species including ducks and raptors. Eimeria spp., which cause severe intestinal coccidiosis, are distributed by geese and diving ducks. These infections are mainly caused by oral ingestion of oocysts excreted from feces. The oocysts of Cryptosporidium baileyi, an intracellular enteric coccidian parasite that can cause gastrointestinal and respiratory tract disorders in birds, have been found in excreta of migratory gulls and Canada geese. Thus, waterfowls can disseminate intestinal protozoan parasites in the environment [4].

Representative virus species that often cause fecal-oral disease transmission in wild birds include Influenza A virus (found in species of ducks, geese, gulls, terns, shearwaters, guillemots, shorebirds, and passerines), Newcastle disease virus (found in many species of free-living birds), anatid herpesvirus 1 (found in many species of anseriform such as ducks, geese, and swans), and aviadenovirus (found in migratory anseriform species) [6, 8].

As vectors of enteropathogens, wild birds have been associated with global outbreaks of water-borne and food-borne diseases. For example, outbreaks of infectious diseases have been attributed to fecal water supply contamination by wild birds [14]. Birds were strongly suspected as a source of enteropathogens for livestock when infected birds were found foraging on the livestock feed, and domestic cats have been known to contract enteropathogens by feeding on infected dead birds [15]. The incidence of infectious diseases in humans has also been linked to the handling of dead wild birds [16].


**Advances in Bio-Based and Biodegradable Polymeric Composites**

Editor

**Evgenia G. Korzhikova-Vlakh**

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2.1.3. Staged Cultivation

Conditions for product accumulation are usually different from those for biomass accumulation [17], the strategy of two-stage process has been found to conquer this paradox. According to this method, there is a new ALE approach named as "chemical modulators based adaptive laboratory evolution" (CM-ALE). The first step used acetyl-CoA carboxylase (ACCase), as a pressure to increase the lipid and docosahexaenoic acid (DHA) productivity of strains by 50% and 90%, respectively. Then, the second step used a sesamol based on the stress of ACCase, to increase the cell growth rate and make the productivity of lipid and DHA up to 100% and 130%, respectively [18]. This demonstrated that the two-step CM-ALE can achieve mutual improvement between desired products and cell growth. The two-stage process was considered as the better approach for productivity improvement. However, the choice of pressure is indispensable with the strategy applied [19]. The understanding of the relationship between carbon metabolism and the ROS quenching mechanism can provide strategies for microalgal production [18].

In addition, heterotrophic cultivation has become a tempting option to increase cell density by overcoming microalgal dependency on light [20]. Therefore, ALE strategy domesticating autotrophic strains to heterotrophic types is a promising approach for high density cultivation of microalgae.

#### *2.2. Choice of Stress Conditions and Equipment*

During microbial ALE, a strain is cultivated under clearly defined conditions for prolonged periods of time. The selective stress serves as the foremost step for the success of ALE, which can be classified into environment stress and the nutrient stress [21]. Microbial characteristics should be considered for selecting pressure. The special properties of microalgal strains are anticipated to amplify to improve the productivity in industrial production. For example, *Chlorella vulgaris*, *Neochloris oleeoabundans* and *Scenedesmus obliquus* [22] are known as producing lipids, so pressure promoting lipid accumulation is preferentially selected, such as nitrogen starvation and high light.

The culture equipment is another important factor. The approaches for ALE usually include serial transfer, colony transfer or chemostat culture [17]. The chemostat is commonly used for the continuous addition of medium and simultaneous removal of culture broth [23]. In addition, ALE is suitable for automation in photobioreactor (PBR) to achieve continuous monitoring, improve experimental robustness, increase throughput and minimize manual labor [24,25].

#### **3. Increased Cell Growth Rate**

The microalgae are a group of prospective resources. Their cultivation is simple, and requires less fresh water and fertile land compared to the other terrestrial plants [26]. Microalgae can be used in the pharmaceuticals, nutraceuticals, biofertilizers, bioplastics, biofuels, cosmetics and feeds for aquaculture and poultry [27–29], consequently addressing environment pollution [30]. The productivity and yield are still the key indicators for the biotechnological and economic feasibility of microalgae [7]. Recently, genetic engineering is applied to improve microalgal growth for large-scale production, which can eventually realize the commercial utilization of microalgae [31,32]. However, the use of transgenic microalgae in outdoor aquaculture systems is still limited for security reasons. Therefore, increasing ideas focus on ALE training, which can avoid risks with high growth rate of microalgae. The existing stress methods for increasing cell growth rate are shown in Table 1.

**Table 1.** Summary of targeting increased growth rate.

Recently, the method to improve the growth rate is mainly performed through controlling light factors by using ALE. In the early process of exploring natural selection, to improve the performance of strains, *C. reinhardtii* was evolved for 1880 generations in liquid medium under continuous light. At the end of experiment, evolved cells had a growth rate that was 35% higher than the progenitor population [38]. This significant growth enhancement was largely due to the improvement of acetic acid metabolism, which showed that the utilization route of organic carbon in algae can provide direction for strain improvement. The process completely transformed the strain at the gene level. In other words,

continuous light can enhance the utilization of acetic acid for fundamental processes, such as DNA replication and protein translation. Although whether the genetic modification was stable or permanent at that time was a subject for debate, it has clearly demonstrated the ability of algae genomes to adapt to environmental changes, and the potential of this strategy for future microalgae engineering, which is later known as ALE. Since then, there have been many studies on regulating light to increase cell growth rates. *C. reinhardtii* was cultivated in TAP media with a light intensity of 50 μmol photons m−2 s−1, the final biomass concentration can reach 1.48 times of the starting strains [39].

Light-emitting diode (LED) is a novel light source, which has the advantages of high efficiency, reliability, long life and low power consumption [40]. For microalgal cultivation, LED allows for artificial control of the spectral output, light intensity and light frequency for light configuration [35]. Biological productivity and light capture efficiency are crucial indicators to evaluate the economic feasibility of production mode by LED technology. Although LED is a little expensive, LED-based PBRs will become practical for producing algal biomass. Using LED-based PBRs for *C. vulgaris* can provide a biomass productivity of up to 2.11 g L−1 d−1, with a light yield of 0.81 g DCW/Einstein. This demonstrated that LED-based PBRs, combined with microalgae biotechnology, can efficiently convert carbon dioxide into biomass and valuable products.

#### **4. Improved Product Yield**

Microalgae provide an abundance of value-added products that can accumulate up to 10–70% of specific biochemical substances (such as lipids and carbohydrates). These components have different functions because of various features. Carotenoids from microalgae can be used in medicine, cosmetics and food; lipid from microalgae can be used as a raw material to produce biodiesel to replace fossil fuels; carbohydrates produced by microalgae can be processed into bioethanol; and astaxanthin from microalgae has strong antioxidant activity and is used in health products, food and feed industries. However, the yield of these active products is not large enough to meet the industrial demand without external interference, so ALE can be applied to obtain high-yield strains for commercial utilization. The existing stress methods for improving product yield are shown in Table 2.

**Table 2.** Summary of targeting increased product yield.


*3.3. E*ff*ects of Prebending Radii on Microstructure*

The TEM images of 7075 aluminum alloy at different prebending radii are shown in Figure 4, where the data indicate that the prebending radii have a significant influence on the microstructure of 7075 aluminum alloy. By measuring over 100 precipitates in TEM images, the average precipitate size

was 60 nm in width and 80 nm in length in the matrix, which was the largest at a prebending radius of 500 mm, and the width of the precipitate free zone (PFZ) was the widest, approximately 100 nm, as shown in Figure 4c. The PFZ width and precipitate size decrease as the prebending radius increases. When the prebending radius was 1000 mm, the width of PFZ was 81 nm, and the average precipitate size was 55 nm in width and 64 nm in length, as shown in Figure 4b. When the prebending radius was 1500 mm, the width of PFZ was only half of that when the radius was 500 mm, and the average precipitate size was 50 nm in width and 60 nm in length, as shown in Figure 4a.

**Figure 4.** TEM microstructure of 7075 aluminum alloy at different prebending radii. (**a,d**) 1500 mm; (**b,e**) 1000 mm; (**c,f**) 500 mm.

Previous studies [23] have shown that stress can increase dislocation density, thus accelerating the rate of phase transformation and growth. In addition, the dislocations have a significant effect on fatigue performance: the higher the number of dislocations, the greater the interface energy, and the greater the stress concentration around the dislocations. As can be seen from Figure 4, at a small stress (the prebending radius was 1500 mm), the precipitated phase in the matrix is a finer dispersion than in the other cases. On the one hand, the smaller the size and the more dispersed the precipitated phase, the stronger the combining capacity between the precipitated phase and the matrix, which can result in stronger fracture toughness, hardness and strength [24]. In this experiment, with the increase of the prebending radius, the size of the precipitated phase becomes smaller and the distribution becomes more homogeneous. Therefore, the hardness and tensile properties of the alloy increased. On the other hand, the smaller the size and the more dispersed the precipitated phase, the better the fatigue performance.

In this experiment, the average number and average length of dislocations were measured on an area of 0.93 μm × 0.93 μm of TEM images more than ten times. The stress was the largest at prebending radius of 500 mm, and thus the average density of dislocations was 7.996 × 109 cm−2 and their average length (77.1 nm) of dislocations were also the largest, as shown in Figure 4f. This, together with the fact that the size of the precipitated phase was also the largest, causes the conditional fatigue limit to be the lowest. The average density of dislocations was 5.239 × 109 cm−2 and the average length was 58.6 nm when the prebending radius was 1000 mm, as shown in Figure 4e. When the prebending radius was 1500 mm, the average density of dislocations was 3.86 × 109 cm−2 and the average length (49 nm) of dislocations were smaller than those at the prebending radius of 500 mm and 1000 mm, and the size of precipitated phase was smallest as well, as shown in Figure 4d, so the fatigue life was the highest.

### *3.4. E*ff*ects of Prebending Radii on Fracture Morphology*

Under 260 MPa, the fatigue fracture topographies of 7075 aluminum alloy after creep age forming with different prebending radii are shown in Figure 5. The data show that there were three typical regions on fatigue fracture topographies, which are marked by A, B and C, where A is the fatigue crack initiation region, B is the fatigue stable propagation region, and C is the fatigue transient fracture region. Some shear lips appeared at the edge of the specimens, which are represented by the white arrow mark.

Under 260 MPa, the morphologies of the fatigue crack initiation regions of 7075 aluminum alloy after creep age forming with different prebending radii are shown in Figure 6. The data show that radial stripes appear in the fatigue crack initiation regions under low magnification (Figure 6a–c), while under high magnification (Figure 6d–f), many fine steps appear in the fatigue initiation regions, which have smooth surface and many tiny cracks. Those steps are the secondary cracks formed in the nucleation process of the crack, but which lose power.

**Figure 5.** Fatigue fracture topography of 7075 aluminum alloy at different prebending radii (*S*max = 260 MPa). (**a**) 1500 mm; (**b**) 1000 mm; (**c**) 500 mm.

**Figure 6.** SEM morphologies of fatigue crack initiation regions of the 7075 aluminum alloy at different prebending radii (*S*max = 260 MPa). (**a,d**) 1500 mm; (**b,e**) 1000 mm; (**c,f**) 500 mm.

Under 260 MPa, the SEM morphologies of the fatigue stable propagation regions of 7075 aluminum alloy after creep age forming with different prebending radii are shown in Figure 7. The data indicate that the fracture shows many fatigue striations and furrows. When the prebending radius was 1500 mm, the average width of the fatigue striation was 0.426 μm, obtained by measuring over 5 strips in SEM images. The average fatigue striation width was 0.308 μm when the prebending radius was 1000 mm and 0.368 μm when the prebending radius was 500 mm.

Under 260 MPa, the SEM images of the fatigue transient fracture regions of 7075 aluminum alloy after creep age forming with different prebending radii are shown in Figure 8. As can be seen from Figure 8, the fracture transient fracture regions show that there were both intergranular fractures and transgranular fractures. Intergranular fracture forms the stratified fracture planes on the fracture surface, while transgranular fracture forms dimples on the fracture surface [25]. When the prebending radius was 1500 mm, the dimples of 7075 aluminum alloy fracture were the largest. As the prebending radius decreases, the dimples become progressively smaller. It indicates that the toughness of the alloy decreases with the decrease of the prebending radius, which was consistent with the decrease in the elongation of the alloy.

**Figure 7.** SEM morphologies of fatigue stability propagation regions of 7075 aluminum alloy at different prebending radii (*S*max = 260 MPa). (**a**) 1500 mm; (**b**) 1000 mm; (**c**) 500 mm.

**Figure 8.** SEM morphologies of fatigue transient fracture region of 7075 aluminum alloy under different prebending radii (*S*max = 260 MPa). (**a**) 1500 mm; (**b**) 1000 mm; (**c**) 500 mm.


**4. Discussion**

## *4.1. Thermal Activation Analysis*

Here we further analyze the lattice-trapped delamination rate data and demonstrate that lattice-trapped delamination is thermally activated. For a system containing a crack of length *a* loaded by hydrostatic stress *σH*, the theory of thermally activated crack growth says that the growth rate is [43]

$$\dot{a}\left(\sigma^{H},a\right) = \dot{a}\_{0}\exp\left(\frac{-E\_{a} + A^{\*}K\left(\sigma^{H},a\right)^{2}/E}{k\_{B}T}\right) \tag{1}$$

where *Ea* is the activation energy for bond breaking, *K* is the stress intensity factor, *A*∗ is the activation area, *E* is the modulus of elasticity, . *a*0 is the exponential prefactor related to the attempt frequency, *T* is the absolute temperature, and *kB* is Boltzmann's constant. It is important to note that Equation (1) is only valid when *K* > *Kc*, the critical stress intensity factor. If *K* < *Kc*, then the free energy of the system increases when the crack grows,

violating the second law of thermodynamics [44]. The stress intensity factor can always be written in the form

$$\mathcal{K} = \mathcal{Y}\sigma^H \sqrt{\pi a} \tag{2}$$

where *Y* is a geometric factor dictated by the geometry of the problem. To relate the crack volume to the crack length, we approximate the crack as an ellipsoid with two axes of radius *a* and the other of radius *a*/2 (consistent with cracks observed in our simulations). The volumetric crack growth rate is then . *V* = 4*πa*2 . *a*. In our simulations where latticetrapped delamination occurs, the crack length does not increase significantly (cracks remain relatively small during lattice-trapped delamination, see Figure 2). Hence, for simplicity, we neglect changes in *a* and assume that *K* = *K σH*, *a* and . *V* = 4*πa*2 . *a*, where *a* is the average crack length during the simulation. With this assumption and using Equation (1), we obtain that the activation enthalpy (numerator in the exponential) is

$$
\Delta H\_{\rm d} = E\_{\rm d} - Ck\_{\rm B} \left( \sigma^{\rm H} \right)^{2} \tag{3}
$$

where *C* = *A*∗*Y*2*πa*/(*EkB*) and simple algebraic manipulation further shows that

$$
\ln \dot{V} = \ln \dot{V}\_0 - \frac{E\_d}{k\_B T} + \mathcal{C} \frac{\left(\sigma^H\right)^2}{T} \tag{4}
$$

where . *V*0 = 4*πa*2 . *a*0. Hence, if we plot ln . *V* from our simulations as a function of *σH* 2 /*T*, the dataset for each temperature should form a straight line with slope *C* if growth is thermally activated. In Figure 10 we plot the data in this way and see a consistent linear trend across all datasets. Specifically, we find that the same slope fits all datasets, indicating that *C* = 258 K/GPa2. Next, we extract the *y*-intercept from each of these linear fits, and Equation (4) indicates that these intercepts should scale with 1/*T*. Figure 11 plots the *y*intercepts from Figure 10 as a function of 1/*T* and once again a linear behavior is recovered as expected. The slope of Figure 10 is −*Ea*/*kB* and the *y*-intercept is ln . *V*0; we obtain values of *Ea* = 1.37 eV and . *V*0 = 1.23 × 109 Å3/ps. The fact that our data so strongly reproduces the behaviors predicted by Equation (4) indicates that the lattice-trapped delamination observed in our MD simulations is indeed thermally activated, and that our neglect of the crack length dependence of *K* does not introduce any significant errors into our analysis.

**Figure 10.** Lattice-trapped delamination rate data from Figure 8 plotted based on the theory of thermally activated crack growth. Dashed lines are linear fits with identical slopes.

**Figure 11.** Arrhenius plot of ordinate intercepts from linear curve fits in Figure 10, showing Arrhenius behavior consistent with the theory of thermally activated crack growth.

The thermally activated delamination mode that we observe is likely governed by the so-called lattice trapping phenomenon [42]. Under lattice trapping, a crack which is loaded supercritically (i.e., with *K* > *Kc*) grows in a step-wise manner as atomic bonds at the crack tip are sequentially broken, often by a kink-pair mechanism [43–46]. As the crack grows, it experiences an oscillating potential energy landscape due to the periodicity of the lattice, and the height of these oscillations dictates the activation energy for growth. To our knowledge this crack growth mode has only been observed in brittle materials like Si [45] and glass [47], but not in ductile materials like Al considered here. This is nonetheless reasonable, since in effect the Al system is acting in a brittle manner in the absence of dislocation activity.

To further analyze our extracted parameters, we need to estimate the stress intensity factor. Tan and Gao [48] numerically determined the stress intensity factor for an axisymmetric interfacial crack on a sphere which forms an angle *φ* from the radial axis, as shown in the inset in Figure 12a, with various modulus ratios *Ep*/*Em* where *m* stands for matrix and *p* for precipitate. We can express their results in the form

$$K\_0 = \mathcal{Y}\left(\phi, E\_p/E\_m\right) \sigma^H \sqrt{\pi R} \tag{5}$$

where *K*0 = *K*2 *I* + *K*2 *I I* is the "overall" stress intensity factor for the mixed-mode loading (the crack is generally mixed mode) and *Y φ*, *Ep*/*Em* was determined by Tan and Gao via numerical boundary integral methods. Using Equation (5) enables us to obtain the activation area as

$$A^\* = \mathbb{C} \frac{k\_B E}{\pi R Y \left(\Phi, E\_p / E\_m\right)^2} \tag{6}$$

where *E* = 2*EmEp*/ *Em* + *Ep* is the bimaterial modulus for interfacial fracture [49]. For approximation purposes, we employ the typical Young's modulus of untextured polycrystals instead of the anisotropic single crystal elastic constants. Estimating *Em* = 70 GPa (experimental value for pure Al) and *Ep* ≈ 120 GPa [50] gives *E* ≈ 88 GPa and *Ep*/*Em* ≈ 1.7. Tan and Gao found that for cracks varying from *φ* = 22.5 to 67.5 degrees with a modulus ratio of *Ep*/*Em* = 2, *Y φ*, *Ep*/*Em* varied from 1.31 to 1.79. Unfortunately, cracks observed in our simulations typically had angles *φ* < 22.5◦, so it is difficult to apply Tan and Gao's solution. Note that according to Equation (5), *Y* → 0 as *φ* → 0 since *K*0 must go to zero when the crack length is zero (i.e., *φ* = 0). Hence, we expect the *Y* values in our simulations to be less than 1.31. Nonetheless, to gain insight into orders of magnitude for the thermal

activation parameters we assume *Y* ≈ 1.31 in the analysis below. Using these parameter values with *R* = 50 Å in Equation (6) leads to *A*∗ ≈ 1.17 *A*2. According to Schoeck [43]

$$A^\* = (1 + \beta)\Delta A\tag{7}$$

where Δ*A* is the atomistic area of crack advance between the equilibrium and saddle position of the crack front and *β* is a factor in the range between 0 and 2. Schoeck argued that for crack advance by breaking of individual bonds, Δ*A* ≈ 1 *A*2; hence, our *A*∗ value gives the correct order of magnitude, further bolstering our conclusion that lattice-trapped delamination is thermally activated.

**Figure 12.** Predictions of lattice-trapped delamination for a crack with *φ* = 22.5◦. (**a**) Stress range over which latticetrapped delamination may operate. (**b**) Lattice-trapped delamination rates for particles of radius *R* = 1 μm and 10 μm at three temperatures.

Finally, we note that an important aspect of thermally activated crack growth is the athermal stress intensity factor, *K*ath, at which the activation enthalpy goes to zero. At and above this load, the crack growth rate is no longer governed by thermally activated bond breaking. According to Equation (1) and accounting for the modulus mismatch, the athermal stress intensity factor is

$$K\_{\rm ath} = \sqrt{\frac{E\_a \overline{E}}{A^\*}}.\tag{8}$$

Using our estimates for parameters above, we obtain that *K*ath ≈ 1.29 MPa·m1/2. According to Equation (5), *K*ath is reached when

$$
\sigma\_{\text{ath}}^H = \frac{K\_{\text{ath}}}{\Upsilon \sqrt{\pi R}} \tag{9}
$$

and using the estimates above we obtain *σH* ath ≈ 7.8 GPa. This value is consistent with our data since we did not observe lattice-trapped delamination above 7.2 GPa (although we did not attempt to obtain a maximum stress where lattice-trapped delamination rates could be obtained).


**4. Conclusions**

In the present study we demonstrated that fatty acid compositional data and sterols have a high differentiation potential as authenticity tools. Meanwhile, analyses on other more or less exploited Greek monocultivars need to be performed in order to reveal and evaluate their quality and chemical characteristics so as to establish a national authenticity databank. Finally, the possibility of investigating other components present in olive oils and taking into account new authenticity methodologies would be useful for the comparison of different Greek monocultivars in the region.

**Author Contributions:** V.S. designed and performed the experiments; P.T. performed statistical analysis; T.V. and V.S. wrote, edited, and reviewed the paper. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research project was funded under the Project "Research and Technology Development Innovation Projects"-AgroETAK, MIS 453350, in the framework of the Operational Program "Human Resources Development." It is co-funded by the European Social Fund through the National Strategic Reference Framework (Research Funding Program 2007–2013) coordinated by the Hellenic Agricultural Organization–DEMETER.

**Acknowledgments:** V.S. would like to thank A.S. Vekiari and the Dept. of Olive and Horticultural crops, Kalamata, Greece, for the support provided. All the experiments were conducted in the accredited laboratory of the Dept. of Olive and Horticultural crops, Kalamata, Greece, according to ISO 17025:2008.

**Conflicts of Interest:** The authors declare no conflict of interest.


**5. OCT classification of macular edema**

Along with the development of OCT imaging, various classifications of DME have been elaborated. The first OCT classification of DME belongs to Otani, and it is based on morphological

**Table 3.** OCT classification of macular edema (after Koleva-Georgieva).

parameters, into three categories: sponge-like swelling, cystoid edema and serous retinal detachment [5]. A fourth category was added by Trichonas et al., posterior hyaloid traction (PHT) [6]. A more detailed classification was proposed by Koleva-Georgieva, and it is based on quantitative and qualitative OCT data: retinal thickness, retinal morphology, retinal topography, macular traction, foveal photoreceptor status (**Table 3**) [8].

treatment in the stage of mild edema had positive outcome. In OS, the high degree of macular

**Figure 1.** OD diffuse mild thickening of the macular region. OS large ovoid spaces of low reflectivity (liquid content) separated by hyperreflective septae located in the neurosensitive retina that represent intraretinal cystoid-like cavities; hyperreflective deposits with posterior shadowing (hard exudates, hemorrhages) in the neurosensory retina; no evidence of PHT; significant increase of the macular thickness, mainly centrally—on the account of the cystoids cavities.

Spectral Domain Optical Coherence Tomography in the Diagnosis and Monitoring of Diabetic…

http://dx.doi.org/10.5772/intechopen.78681

47

In this case, intravitreal anti-VEGF injections alone would probably not lead to the resolution of edema, because vitreo-macular traction is also involved in its pathophysiology. Therefore, pars plana vitrectomy with dissection of the posterior hyaloid from the macular area was

In this case, anti-VEGF injections are indicated in AO, but with a much better prognosis in LE where edema is mild, as compared to RE in which the macula is disorganized (**Figures 5**

In this case, beside anti-VEGF injections, pars plana vitrectomy appears reasonable in order to

Even if macular edema is mild, intravitreal anti-VEGF would prevent its progression toward

On the ground of the OCT aspect, intravitreal anti-VEGF injections are indicated in OD, but

disorganization prevented a significant improvement in vision (**Figure 2**).

release the traction exerted by the posterior hyaloid on the macula.

not in LE in which retinal atrophy is present (**Figure 8**).

more advanced stages with cystoid degeneration of the macula (**Figure 7**).

indicated (**Figures 3** and **4**).

and **6**).


5.1.5. Project Level

Project-level decisions involve the project director, designers, maintenance engineers, schedulers, and many other engineers responsible for project implementation at the projectimplementing unit. For effective decision-making, dimensions such as accuracy, consistency, and completeness from the syntactic level; and accessibility and timeliness from the empiric level are considered critical out of all 20 data quality dimensions. At the project level, its primary concern is data generation, the physical form of data generation, and storage for information generation. Therefore, the dimensions in the semantic and pragmatic categories that deal with information and knowledge generation are not of as high importance as the syntactic and empirics level at the project level.

### *5.2. Ranking of Dimensions within the Semiotic Framework Categories*

Garrett's ranking technique was used to analyse various dimensions for ranking the dimensions within the semiotic framework levels. The decision-makers were asked to rank the dimensions within the framework to understand their preferences for data quality dimensions within the semiotic framework. The semiotic framework comprised syntactic, empiric, semiotic, and pragmatic categories, which deal with the structure, meaning, information, and knowledge of data characteristics [32]. Before ranking the dimensions within the semiotic framework levels, the percentage position for the ranks and their corresponding Garrett value were calculated using Equation (1), as shown in Table 5. The total score was calculated for factors by multiplying the number of stakeholders ranking that dimension (Garrett and Woodworth [76]).

**Table 5.** Percentage position and Garrett value for rank 1 to 7.


*4.4.5 Summary of findings*

**Table 5** provides a summary of the functional use of the CMMS tool by AICC industry. Currently, the maintenance unit have activated and effectively using the different components of the maintenance management modules, as well as create synergy with other divisions of the industry. This will facilitate automation of operation and help in achieving the objectives of smart maintenance.


*5.4. Thermal Stability of MTase with Mg2+*

A thermal denaturation study of MTase was performed on a specific wavelength (222 nm) using far-UV CD experiments, further analysed based upon the two-state unfolding model. In the case of a single-step unfolding process, NU, where N refers to the native state and U to the unfolded state, and *K*u for the equilibrium constant with *f* u and *f* n are the molar fractions of U and N, respectively.

$$K\_{\mathbf{u}} = \frac{f\_{\mathbf{u}}}{f\_{\mathbf{n}}} \tag{2}$$

$$f\_{\mathbf{d}} = \frac{\left(Y\_{\text{obs}} - Y\_{\text{n}}\right)}{\left(Y\_{\text{u}} - Y\_{\text{n}}\right)} \tag{3}$$

where *Y*obs, *Y*n, and *Y*u reflect the observed property, property of the native state, and property of the unfolded state, respectively.


Preface

"Trust me, I'm a doctor."

That statement has been the title of a song, a book, a TV show and used in the advertising of Dr. Pepper. It has made it into modern culture and embodies the belief that we should and do trust doctors.

I am a doctor. In my professional life, I want my patients to trust me. I also hope that readers will put their trust in the experience and knowledge of the authors of this book. However, I never want my patients to blindly trust me. I want them to ask questions or offer their observations and experiences. In that same way, I don't want you as the reader to blindly trust these chapters. I hope that you will use them as a jumping-off point. I want you to contemplate the ideas that we offer but bring your own questions to the discussions. Perhaps you will be inspired to consider a new aspect of trust.

This book offers a variety of thoughts about trust. Trust has always been complicated. How do we know when to trust another person? How do we know how to trust ourselves? I often work with patients who are very critical of themselves. We work in therapy to recognize that our thoughts are not always the truth. So how do we trust and know what is real?

Trust has become more complicated with the advent of the internet. We can now connect with more ideas and individuals. Yet, is the person who communicates back with us real? Is it someone with a fake account or maybe not even a person at all, but a robot? Even though trust is complicated and we can sometimes be taken advantage of, we still need to find ways to trust others in our lives. Trust allows us to develop a community. We have always needed the community to be safe, both physically and emotionally.

Once, in group therapy, the patients and I discussed how we know if we can trust someone. Some of the guidelines included whether they told the truth to the best of their ability. We looked at reliability. We discussed the need for someone to be compassionate and not emotionally or physically abusive. How can we trust someone if they are hurting us or taking advantage of us? We discussed ways to re-establish trust allowing someone in bit by bit. Trust can be a process of development. Yes, it takes a final leap of faith but one that is built on evidence that the person has done what they promised, has been there for us, and will continue to honor and respect our values.

We value you as a reader and hope that you will find that we have completed what we promised to do - provide a look at the psychology of trust.

> **Martha Peaslee Levine, MD** Penn State College of Medicine, Hershey, PA, USA


**5. Neural controllers**

**4. Autonomy**

**4.1. Artificial neural networks**

Our approach to autonomous robots is based in autonomous controllers, constructed with artificial neural nets, and incorporating basic rules of living brains in terms of energy usage, default mode network (DMN), and the orchestrated, autonomous transitions forms default

**Figure 2.** The basic robotic joint with sensors, muscles, and neural driver. The joint can be snapped into long chains.

**Figure 3.** Modular robot with 16 joints and dedicated driven neurons in its working environment.

The neural networks used in this chapter are sigmoidal neurons trained with backpropaga-

mode to other operative behaviors in reaction to stimuli.

Muscles are driven by the output neurons of an associate network.

130 Human-Robot Interaction - Theory and Application

tion [17]. Other functioning details are given in [12, 13].