**Yoo Gyeong Park 1 and Byoung Ryong Jeong 1,2,3,\***

Received: 19 October 2020; Accepted: 27 November 2020; Published: 2 December 2020

**Abstract:** This research examined the effects of the supplementary or night-interrupting (NI) blue (B) light supplied at a low intensity on the flowering, gene expression, and morphogenesis of chrysanthemum, a qualitative short-day plant. White (W) light-emitting diodes (LEDs) were used to provide light with a photosynthetic photon flux density (PPFD) of 180 µmol·m−2 ·s −1 during the photoperiod to grow the plants in a plant factory. The control group was constructed with plants that were exposed to a 10-h short day (SD10) treatment without any blue light. The B light in this research was used for 4 h to either (1) extend the photoperiod for plants at the end of a 9-h short day (SD) treatment as the sole light source (SD9 + 4B), (2) provide night interruption (NI) to plants in the 13-h long-day (LD) treatment (LD13 + NI − 4B), (3) provide NI to plants in the 10-h SD treatment (SD10 + NI − 4B), or (4) supplement the W LEDs at the end of a 13-h LD treatment (LD13 + 4B). Blue LEDs were used to provide the supplementary/NI light at 10 µmol·m−2 ·s −1 PPFD. The LD13 + NI − 4B treatment resulted in the greatest plant height, followed by LD13 + 4B. Plants in all treatments flowered. It is noteworthy that despite the fact that chrysanthemum is a qualitative SD plant, chrysanthemum plants flowered when grown in the LD13 + 4B and LD13 + NI − 4B treatments. Plants grown in the LD13 + 4B had the greatest number of flowers. Plants grown in the LD13 + 4B treatment had the highest expression levels of the *cryptochrome 1*, *phytochrome A*, and *phytochrome B* genes. The results of this study indicate that a 4-h supplementation of B light during the photoperiod increases flower bud formation and promotes flowering, and presents a possibility as an alternative method to using blackout curtains in LD seasons to practically induce flowering. The B light application methods to induce flowering in SD plants requires further research.

**Keywords:** blue LED; flower bud formation; number of flowers; photoperiod


**Author details**

Qinling Bi, Shengyu Zhu and Weimin Liu

*State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, PR China*

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[21] Li SZ, Jiang XX, Yin FC, Peterson MB, Calabrese SJ. On self-lubricating behavior of Ni - Cu-Re alloys at elevated temperature. Chinese Journal of Materials Research1989; 3:

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[25] Wang Y, Wang JB, Wang JA, Zhao JZ, Ouyang JL. Study on the Nickel Alloy Containing Sulfide and Its Tribological Properties at High Temperature. Tribology (in Chinese)

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2. Sensor for CO2 detection with mixed binary oxide CeO2-Nb2O5 sensitive material

Niobium oxide has some properties that make it in principal as promising for catalytic applications. Niobia-based materials are effective catalysts in selective oxidation reactions due to its redox properties. Also, niobia-doped ceria materials have shown a good carbon deposition and excellent properties as solid oxide fuel cell (SOFC) anodes [35]. Nb5+ ions (ionic radius of Nb5+: 78 pm) may initiate the reduction of Ce4+ to Ce3+ by the doping Nb into the CeO2 structure, which results in formation of oxygen vacancies. Using the Kröger-Vink notation, it can mention two mechanisms for the dissolution: one of which occurs by electronic compensation (Eq. 2) and the other by consumption of vacancies (Eq. 3), as shown below [3, 36, 37].

$$\text{Nb}\_2\text{O}\_5 + \text{Ce}\_M\* \to 2\text{Nb}\_M + 4\text{O}\_0^\* + \frac{1}{2}\text{O}\_2 + 2\text{Ce}\_M^\prime \tag{2}$$

$$\text{N}b\_2O\_5 + V\_0^\cdot \to 2\text{N}b\_M^\cdot + 5O\_o^\ast \tag{3}$$

where O∗ o , V∙∙ o represent oxygen and oxygen vacancies on the oxygen sites, Ce∗ M, Ce= M represent cerium (Ce4+) and negatively charged cerium ions (Ce3+) on metal sites M, Nb∙ M metal vacancy. Nb2O5 it is known as an n-type oxide semiconductor with a band gap about 3.4 eV. Because of its good physicochemical properties and structural isotropy, it is used in other range of applications such as: in construction of gas sensing, field-emission displays and microelectronics electrochromics display and photoelectrodes [38].

## 2.1. Synthesis of mixed oxides CeO2-Nb2O5 sensitive material

In our case, we used the mixed binary oxides CeO2-Nb2O5 for CO2 detection. Sensitive element is composed from mechanical mixing of CeO2 (97%) and Nb2O5 (3%); both reagents purchased from Merck. The powder oxides were treated with a few drops of ethylic alcohol for ink obtaining and then introduced in a ball mill for homogenization followed by calcination at 500, 600 and 800�C for 1 hour. The powder calcined at 600�C was pressed in disc form at 2 tons force/cm2 with the dimensions ∅4 � 1 mm and mounted on the ambasis transistor. The sensor image is showed in Figure 1 [39].

Figure 1. Image of the CO2 sensor made with mixed oxides CeO2-Nb2O5 sensitive material.

#### 2.2. Structural characterization

Calcined mixed powder oxides were characterized by X-ray diffraction using a diffractometertype X Bruker-AXS type D8 ADVANCE in conditions: CuKα radiation (λ =1.54059 Å), 40 kV/ 40 mA, filter kβ of Ni. pas: 0.04 , measuring time on point: 1 s, measure range 2θ = 10–100 . The mixed oxides powder with composition CeO2–3%Nb2O5 was calcined at 500, 600 and 800C for 1 hour. It shows a cubic phase for CeO2 and orthorhombic phase for Nb2O5, Figure 2. Also, for this powder that was calcined at 800C, was identified in addition a hexagonal Ce2O3 phase (Figure 3). It obtain for CeO2 cell parameter a = b = c = 5.407 Å. This is in accord with theoretical value of a = 5.404 Å as well as in according with card number 03–065-5923. The cell parameters for Nb2O5 orthorhombic phase were a = 6.175 Å, b = 29.175 Å and c = 3.930 Å in accord with card number 30-0873 [4]. Corresponding to hkl (Miller indices) 111, 200, 220 and 311, the crystallites size determined with Scherrer formula give values of 160.9, 145.6, 117.4

Prototyping a Gas Sensors Using CeO2 as a Matrix or Dopant in Oxide Semiconductor Systems

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65

The gas sensors testing were performed with the apparatus as presented in Figure 4. It is realized by SYSCOM-18 Romania for National Institute for Research and Development in

2.3. CO2 gas sensor made with mixed oxides CeO2-Nb2O5 sensitive material tested

and 63.5 nm.

in automated process mode

Figure 4. The testing gas sensor installation.

Figure 3. X-ray diffraction of CeO2-Nb2O5 calcinated at 800C.

Figure 2. X-ray diffraction of CeO2-Nb2O5 calcinated at: (a) 500C; (b) 600C and (c) 800C.

Prototyping a Gas Sensors Using CeO2 as a Matrix or Dopant in Oxide Semiconductor Systems http://dx.doi.org/10.5772/intechopen.80801 65

Figure 3. X-ray diffraction of CeO2-Nb2O5 calcinated at 800C.

2.2. Structural characterization

64 Cerium Oxide - Applications and Attributes

40 mA, filter kβ of Ni. pas: 0.04

Calcined mixed powder oxides were characterized by X-ray diffraction using a diffractometertype X Bruker-AXS type D8 ADVANCE in conditions: CuKα radiation (λ =1.54059 Å), 40 kV/

Figure 1. Image of the CO2 sensor made with mixed oxides CeO2-Nb2O5 sensitive material.

Figure 2. X-ray diffraction of CeO2-Nb2O5 calcinated at: (a) 500C; (b) 600C and (c) 800C.

mixed oxides powder with composition CeO2–3%Nb2O5 was calcined at 500, 600 and 800C for 1 hour. It shows a cubic phase for CeO2 and orthorhombic phase for Nb2O5, Figure 2. Also, for this powder that was calcined at 800C, was identified in addition a hexagonal Ce2O3 phase (Figure 3). It obtain for CeO2 cell parameter a = b = c = 5.407 Å. This is in accord with

, measuring time on point: 1 s, measure range 2θ = 10–100

. The

theoretical value of a = 5.404 Å as well as in according with card number 03–065-5923. The cell parameters for Nb2O5 orthorhombic phase were a = 6.175 Å, b = 29.175 Å and c = 3.930 Å in accord with card number 30-0873 [4]. Corresponding to hkl (Miller indices) 111, 200, 220 and 311, the crystallites size determined with Scherrer formula give values of 160.9, 145.6, 117.4 and 63.5 nm.

## 2.3. CO2 gas sensor made with mixed oxides CeO2-Nb2O5 sensitive material tested in automated process mode

The gas sensors testing were performed with the apparatus as presented in Figure 4. It is realized by SYSCOM-18 Romania for National Institute for Research and Development in

Figure 4. The testing gas sensor installation.

Figure 5. Variation of the voltage depending on time for CO2 sensor, made with mixed oxides CeO2-Nb2O5 sensitive material.

Figure 6. A simplified schematic of the AD620 [39].

Prototyping a Gas Sensors Using CeO2 as a Matrix or Dopant in Oxide Semiconductor Systems

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67

Figure 7. AD620 closed-loop gain versus frequency [39].

Electrical Engineering ICPE-CA. The voltage measurements were effected by testing module, in automated process mode. A control panel provides a lot of measuring values, at rate 1/10 s. The bench of testing for the gas sensor consists in an enclosure where there are set of testing conditions for the sensor as well as in connected equipment. The whole process of testing is automated, being controlled by a programmable automaton. The gas for testing is introduced in a controlled way in the testing enclosure, through a mass debit meter. In the testing, enclosure is set a constant temperature, controlled by a temperature regulator.

The gas testing was done in concentration of 10,000 ppm CO2 at the 25, 50 and 70C chamber test temperature. The sensor was developed the voltages values of 48, 50 and 770 mV (Figure 5) [39].

The experimental data shows a good sensor response for CO2 detection with increasing temperature.


*Article* **Substance-P Restores Cellular Activity of ADSC Impaired by Oxidative Stress**

#### **Jeong Seop Park 1 , Jiyuan Piao 2 , Gabee Park 2 and Hyun Sook Hong 1,3,\***

Received: 15 September 2020; Accepted: 11 October 2020; Published: 12 October 2020

**Abstract:** Oxidative stress induces cellular damage, which accelerates aging and promotes the development of serious illnesses. Adipose-derived stem cells (ADSCs) are novel cellular therapeutic tools and have been applied for tissue regeneration. However, ADSCs from aged and diseased individuals may be affected in vivo by the accumulation of free radicals, which can impair their therapeutic efficacy. Substance-P (SP) is a neuropeptide that is known to rescue stem cells from senescence and inflammatory attack, and this study explored the restorative effect of SP on ADSCs under oxidative stress. ADSCs were transiently exposed to H2O2, and then treated with SP. H2O2 treatment decreased ADSC cell viability, proliferation, and cytokine production and this activity was not recovered even after the removal of H2O2. However, the addition of SP increased cell viability and restored paracrine potential, leading to the accelerated repopulation of ADSCs injured by H2O2. Furthermore, SP was capable of activating Akt/GSK-3β signaling, which was found to be downregulated following H2O2 treatment. This might contribute to the restorative effect of SP on injured ADSCs. Collectively, SP can protect ADSCs from oxidant-induced cell damage, possibly by activating Akt/GSK-3β signaling in ADSCs. This study supports the possibility that SP can recover cell activity from oxidative stress-induced dysfunction.

**Keywords:** Substance-P; adipose-derived stem cells; oxidative stress; paracrine factors

### **1. Introduction**

Oxidative stress is an imbalance of free radicals and antioxidants in the body, which can lead to cell and tissue damage. There are several factors that cause oxidative stress and excess free radical production, including obesity, smoking, alcohol consumption, pollution, and chemicals. These risk factors can activate immune cells, which subsequently produce free radicals and impair normal cells. Consistent accumulation of free radicals and cellular damage causes inflammation, contributing to the development of serious diseases including cancer, diabetes, Alzheimer's, and cardiovascular diseases.

Aging is the progressive loss of tissue and organ function over time. Oxidative stress is believed to be closely related to the aging process because age-associated functional losses are caused by the accumulation of oxidative damage to macromolecules. Although the exact mechanism of oxidative stress-induced aging is unclear, increased free radical production obviously leads to cellular senescence, decreased cell proliferation, and increased inflammatory cytokine production [1]. In addition, several studies have found that with aging, endogenous antioxidant levels, antioxidant enzyme activity, gene expression, and protein levels decrease. This alteration in the antioxidant defense system worsens ROS imbalances and contributes to oxidative-stress-induced aging [1–4].

Oxidative stress and cellular senescence are involved in several acute and chronic pathological processes such as cardiovascular diseases (CVDs), acute and chronic kidney disease (CKD), neurodegenerative diseases (NDs), macular degeneration (MD), biliary diseases, and cancer. Cardiovascular (CV) risk factors are associated with the inflammatory pathway mediated by interleukin (IL)-1α, IL-6, IL-8, and with increased cellular senescence [5]. The associations between oxidative stress, inflammation, and aging produce a vicious cycle whereby chronic ROS production and inflammation feed each other and accelerate aging and age-related morbidity [6]. Thus, modulating oxidative stress-mediated cellular injury may be a fundamental solution to prevent the progression of lethal diseases in aged individuals.

Stem cells facilitate tissue repair in vivo, and many, such as bone marrow, adipose-derived, and umbilical cord blood stem cells are currently being used as novel treatments for various diseases. The application of mesenchymal stem/stromal cells (MSCs) in regenerative medicine has been intensively studied in many clinical trials, as these cells represent a promising source of multipotent adult stem cells for cell therapy and tissue engineering [7–12]. The therapeutic effects of MSCs are generally mediated by various secreted cytokines, growth factors, extracellular matrix proteins, and factors involved in matrix remodeling, as well as different types of extracellular vesicles.

Currently, as alternative of bone marrow stem cells, adipose-derived stem cells (ADSCs) are being applied extensively in the clinic because they can be easily isolated and cause lower donor-site morbidity [12–14]. Aging, oxidative stress, and/or inflammation can affect tissue-resident cells as well as circulating cells, which suggests that stem cells may also be influenced by oxidative stress in vivo. Considering that the aged population is the main population to be treated by stem cell therapy, the restoration of the cellular function of stem cells injured by oxidative stress is likely important.

Substance-P (SP) is an endogenous neuropeptide that interacts with neurokinin receptor 1 (NK-1R). SP has been reported to stimulate cell proliferation and prevent apoptosis under inflammatory or oxidative stress by activating the extracellular signal-regulated kinases 1/2 (ERK 1/2) or Akt and by translocating β-catenin to cell nuclei [15–18]. SP could suppress inflammation to promote tissue repair in severe diseases by modulating the immune cell profile in circulation-associated and lymphoid organs [19–22]. Moreover, SP can recover the cellular activity of senescent stem cells [23,24] and stimulate stem cell mobilization from the bone marrow to the peripheral blood [17].

Considering these functions of SP, we hypothesized that SP would be able to restore stem cells from oxidative stress-induced injury. To explore the potential recovery role of SP in injured stem cells due to oxidative stress, ADSCs were exposed to H2O2 at various concentrations. Subsequently, SP was added to the damaged ADSCs and the effect of SP was assessed by evaluating cell viability, cell proliferation, paracrine factors, and early signaling molecules.

#### **2. Materials and Methods**

#### *2.1. Materials*

SP and phenylmethylsulfonyl fluoride (PMSF) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Penicillin/streptomycin, 0.25% trypsin-EDTA solution, and phosphate-buffered saline (PBS) were provided by Welgene (Daegu, Korea). Fetal bovine serum and alpha-MEM were purchased from Gibco (Grand Island, NY, USA). An anti-GAPDH antibody (Abcam, Cambridge, MA, USA), and anti-WST-1 antibody (Roche; Indianapolis, IN, USA) were used in this study. Cell lysis buffer, anti-Akt antibody, anti-phospho-Akt antibody, anti-GSK-3β antibody, and anti-phospho-GSK-3β antibody were purchased from Cell Signaling Technology (Danvers, MA, USA).

#### *2.2. Cell Culture*

Healthy adipose tissues were provided by the Kyung Hee University Hospital Institutional Review Board (eight donors, M6/F2; Seoul, Korea; (IRB# 2016-12-022)). All consents were informed. Fat tissue (two fat tissues (1 × 1 cm) from one donor; total 16 tissues) washed twice with PBS, and treated with

collagenase (GMP grade, Vivagen, Los Angeles, CA, USA) for 1 h at 37 ◦C. Red blood cells and debris were removed using a cell strainer (SPL Life, Pocheon, Korea). The vascular fraction was seeded in α-MEM supplemented with 10% FBS at 37 ◦C with 5% CO2. ADSCs were characterized by analyzing the expression of CD29, CD73, CD105, and CD90 using a fluorescence-activated cell sorting (FACS) Calibur flow cytometer and CELLQuest software (Becton Dickinson, San Jose, CA, USA) (Figure S1).

### *2.3. Hydrogen Peroxide Exposure Procedure and SP Treatment*

Cells were seeded in a 96-well plate at a density of 1 × 104 cells/well or in a 6-well plate with a density of 3 × 104 cells/well. These cells were allowed to adhere to the bottom of the well. Twenty-four hours later, different concentrations of H2O2 (50, 100, 200, 300, and 400 µM) were added to the wells for 2 h and then removed by changing the culture media. After 24 h, SP was added to each well at a final concentration of 100 nM, and this was repeated 24 h later.

#### *2.4. Wst-1 Assay*

Ten microliters of water-soluble tetrazolium salt (WST-1; Roche) solution was added to each well at 10% the total volume of the medium, and the 96-well-plate was incubated for 1 h at 37 ◦C in 5% CO2. After incubation, the optical density values were measured at a wavelength of 450 nm using an Enzyme Linked Immunosorbent Assay (ELISA) microplate reader (Molecular Devices, Sunnyvale, CA, USA).

#### *2.5. Enzyme Linked Immunosorbent Assay (ELISA)*

The total TGF-β1 and VEGF levels in the supernatants were quantified using ELISA kits, according to the manufacturer's instructions. In brief, standards and samples were added to the wells of anti-TGF-β1 or anti-VEGF antibody-coated 96-well plates and incubated for 2 h at room temperature. After discarding the supernatant, a horseradish peroxidase-conjugated secondary antibody was added to each well and incubated again for 2 h at room temperature. After rinsing with washing solution three times, 100 µL of substrate solution was added, followed by the addition of 100 µL of stop solution. The optical density was measured at 450 nm using an ELISA microplate reader (Molecular Devices, Sunnyvale, CA, USA).

#### *2.6. Preparation of Cell Extracts and Western Blot Analysis*

Cells were rapidly washed with chilled 1× PBS and lysed with 1× lysis buffer/1 mM phenylmethylsulfonyl fluoride (PMSF) solution. Cells were then scraped and supernatants were collected by centrifugation (Rotor radius: 70 mm) at 12,000 rpm for 10 min at 4 ◦C. Protein concentrations of lysates were determined using the bicinchoninic acid (BCA) assay (Thermo Fisher, Rockford, IL, USA). Ten micrograms of lysates were denatured and electrophoresed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transferred to a nitrocellulose membrane. After blocking with 5% skim milk, membranes were incubated with primary anti-Akt, anti phospho-Akt, anti-GSK-3β, anti-phospho-GSK-3β, or anti-GAPDH antibodies, followed by an anti-IgG horseradish peroxidase-conjugated secondary antibody. The blots were processed using enhanced chemiluminescence (GE Healthcare, Buckinghamshire, UK).

#### *2.7. Statistical Analysis*

All data are presented as the mean ± standard deviation (SD) of more than three independent experiments. *p* values of less than 0.05 were considered statistically significant. Statistical analysis of the data was carried out using an unpaired, two-tailed Student's *t*-test.


3. Some geometrical peculiarities of the wheel and rail interaction

The geometrical features of the wheel and rail interaction are stipulated by the designs of the rail track/bogie, wheel/rail, and their technical state. At lateral displacement of the wheelset relative to the rail, a contact point from the tread surfaces passes on the wheel flange root and rail corner, and the wheel and rail tread surfaces separate from each other. At further lateral displacement of the wheelset, the contact point passes on their steering surfaces, and the angle of inclination of the wheel flange increases up to 70° .

It is difficult to predict and control the friction forces, wear rate of various types, vibrations, and noise of the heavy loaded interacting surfaces of the railway transport running gear that decreases traffic safety, increases energy loses on friction, etc. Many works are devoted to the researches of dependences of the tribological

properties on various factors [1, 3–6], though their mechanisms of generation and variation are not always entirely clear that complicates the revelation of parameters influencing them [7, 8].

certain combination of such parameters, as radius of the rail track curvature, mass and speed of the rolling stock, friction coefficient between the wheel and rail, etc. Therefore, practically the outer wheel rolls on the less diameter than necessary, and in the case of the free wheelset (without bogie), it falls behind the inner wheel,

In the case of the non-free wheelset, the bogie makes the wheelset maintain a radial position, forcing the outer wheel to roll the greater distance not to fall behind the inner wheel. Thereat, the outer wheel rotates through the greater angle than the inner one, and the wheelset axle is twisted. The angle of twist of the wheelset can increase up to the value that is stipulated by the friction force between the wheel and rail. When this angle of twist reaches the limited value, the wheel slides on the rail due to action of the wheelset axle elastic moment tending to bring it back to the

Similarly, the wheel will slide on the rail at rolling in the straight rail track of the

At pure rolling of the free wheelset (without bogie) in the curved rail track with radius of curvature R of the internal rail, its axle will be inclined from radial position because both wheels will have passed equal distances l. However, in the wagon wheelset rolling with velocity V, the outer wheel is constraint to maintain the radial position and pass greater distance l + Δl, rotating relative to the inner wheel in the clockwise direction if it is seen from axial direction A (Figure 5). At that, the wheelset axle is twisted through angle φ equal to the ratio of the difference Δl of the outer and inner arcs to the radius D/2 of the wheel tread surface, supposing that

φ ¼ 2Δl=D (1)

Δl ¼ lΔR=R, (2)

φ ¼ 2 lΔR=DR: (3)

wheelset with the wheels of different diameters or with one wheel having an elliptical form. The mechanisms of the wheel sliding on the rail for the three noted

cases are considered and explained in the next paragraphs.

both wheels are rolling on the tread surfaces of equal diameters:

From the drawing α = l/R = (l + Δl)/(R + ΔR) = Δl/ΔR,

Movement of the wagon wheelset in the curve and wheelset shaft slope from the radial position.

3.1 Movement of the wagon wheelset in the curve

inclining the wheelset axle from the radial position.

DOI: http://dx.doi.org/10.5772/intechopen.89135

Influence of Tribological Parameters on the Railway Wheel Derailment

equilibrium position.

from where

and therefore

Figure 5.

211

There are many reasons of generation of vibrations and noise at movement of the train, part of which are well studied and predictable, and ways of their decrease are known. The interacting surfaces of the wheels and rails are characterized by the various types of irregularities, 5–20 mm gaps in the rail joints, where the rail tread surfaces are spaced by 0.5–2 mm in the vertical direction; the various wear traces (rail corrugation, fatigue, etc.) and deviations from the wheel roundness are the sources of vibrations and noise.

The wheel and rail interaction is accompanied by the forced and self-excited vibrations of various frequencies, as the main reason of the forced vibrations is considered macro- and micro-asperities of the rail (periodic and separate asperities) [9–13]. However, the main source of the self-vibrations is friction between the wheel and rail. It must be noted that to various working conditions of the heavy loaded contacting surfaces and wear types correspond typical micro-asperities, which can be different from the initial micro-asperities [27, 28]. The researches have shown an important role of the tread and steering surfaces in generation of the vibrations (self-vibrations) and noise, whose reasons are not studied sufficiently. There is quite vague information on the reasons of the self-vibrations generated at interaction of the wheel and rail [9].

Generation of vibrations of the heavy loaded interacting elements of the railway transport running gear is stipulated by the complex processes proceeding in the contact zone. As a result of interaction of the surfaces with the environment, they are coated by the layers of various physical and chemical origins that are the components of the third body in the contact zone and have a great influence on the tribological properties of the contacting surfaces. According to observations by Godet, dry friction is largely determined not by the properties of materials of the contacting pair but by the characteristics of the structure and composition of the thin film that is formed on the surfaces of both bodies because of compaction of the wear product and its chemical composition and oxidation. Destination of the third body in the tribological systems is separation of the contacting surfaces, providing with the stable friction forces of proper values and protection of the surfaces against damage of various types. Tribological properties of the third body greatly depend on the initial properties of its component elements and features of the contact zone. The sliding velocity, power and thermal loading, and the sliding distance have especially great influence on the destruction of the third body. For providing the stability of the third body in the contact zone of the wheels and rails and reduction of the derailment probability, energy consumed on traction, environment pollution, and maintenance expenses, the decrease of the sliding distance and relative sliding is especially important.

The wheel/rail squeal in curves is the most common type of vibrations and noise. It is especially typical for high-speed movements, when because of various reasons, the relative sliding and sliding distance increase. This contributes destruction of the third body, seizure of the surfaces at direct contact, subsequent destruction of the seized surfaces, and instability of the friction forces and relative movement of surfaces.

Many negative phenomena (wear, noise, vibrations) are generated because of the wheel sliding on the rail. For elimination of the wheel sliding in the curves, the wheel tread surface is given a conical form with the intention of making the outer wheel to roll on the greater diameter passing the greater distance than the inner wheel and rotate both wheels through the equal angles, maintaining this way radial position of the wheelset axle. However, this intention can be realized only for a

### Influence of Tribological Parameters on the Railway Wheel Derailment DOI: http://dx.doi.org/10.5772/intechopen.89135

certain combination of such parameters, as radius of the rail track curvature, mass and speed of the rolling stock, friction coefficient between the wheel and rail, etc. Therefore, practically the outer wheel rolls on the less diameter than necessary, and in the case of the free wheelset (without bogie), it falls behind the inner wheel, inclining the wheelset axle from the radial position.

In the case of the non-free wheelset, the bogie makes the wheelset maintain a radial position, forcing the outer wheel to roll the greater distance not to fall behind the inner wheel. Thereat, the outer wheel rotates through the greater angle than the inner one, and the wheelset axle is twisted. The angle of twist of the wheelset can increase up to the value that is stipulated by the friction force between the wheel and rail. When this angle of twist reaches the limited value, the wheel slides on the rail due to action of the wheelset axle elastic moment tending to bring it back to the equilibrium position.

Similarly, the wheel will slide on the rail at rolling in the straight rail track of the wheelset with the wheels of different diameters or with one wheel having an elliptical form. The mechanisms of the wheel sliding on the rail for the three noted cases are considered and explained in the next paragraphs.

#### 3.1 Movement of the wagon wheelset in the curve

At pure rolling of the free wheelset (without bogie) in the curved rail track with radius of curvature R of the internal rail, its axle will be inclined from radial position because both wheels will have passed equal distances l. However, in the wagon wheelset rolling with velocity V, the outer wheel is constraint to maintain the radial position and pass greater distance l + Δl, rotating relative to the inner wheel in the clockwise direction if it is seen from axial direction A (Figure 5). At that, the wheelset axle is twisted through angle φ equal to the ratio of the difference Δl of the outer and inner arcs to the radius D/2 of the wheel tread surface, supposing that both wheels are rolling on the tread surfaces of equal diameters:

$$
\boldsymbol{\upvarphi} = \boldsymbol{\upDelta l}/\boldsymbol{\upDelta l} \tag{1}
$$

From the drawing α = l/R = (l + Δl)/(R + ΔR) = Δl/ΔR, from where

$$
\Delta \mathbf{l} = \mathbf{l} \Delta \mathbf{R} / \mathbf{R},
\tag{2}
$$

and therefore

properties on various factors [1, 3–6], though their mechanisms of generation and variation are not always entirely clear that complicates the revelation of parameters

There are many reasons of generation of vibrations and noise at movement of the train, part of which are well studied and predictable, and ways of their decrease are known. The interacting surfaces of the wheels and rails are characterized by the various types of irregularities, 5–20 mm gaps in the rail joints, where the rail tread surfaces are spaced by 0.5–2 mm in the vertical direction; the various wear traces (rail corrugation, fatigue, etc.) and deviations from the wheel roundness are the

The wheel and rail interaction is accompanied by the forced and self-excited vibrations of various frequencies, as the main reason of the forced vibrations is considered macro- and micro-asperities of the rail (periodic and separate asperities) [9–13]. However, the main source of the self-vibrations is friction between the wheel and rail. It must be noted that to various working conditions of the heavy loaded contacting surfaces and wear types correspond typical micro-asperities, which can be different from the initial micro-asperities [27, 28]. The researches have shown an important role of the tread and steering surfaces in generation of the vibrations (self-vibrations) and noise, whose reasons are not studied sufficiently. There is quite vague information on the reasons of the self-vibrations generated at

Generation of vibrations of the heavy loaded interacting elements of the railway transport running gear is stipulated by the complex processes proceeding in the contact zone. As a result of interaction of the surfaces with the environment, they are coated by the layers of various physical and chemical origins that are the components of the third body in the contact zone and have a great influence on the tribological properties of the contacting surfaces. According to observations by Godet, dry friction is largely determined not by the properties of materials of the contacting pair but by the characteristics of the structure and composition of the thin film that is formed on the surfaces of both bodies because of compaction of the wear product and its chemical composition and oxidation. Destination of the third body in the tribological systems is separation of the contacting surfaces, providing with the stable friction forces of proper values and protection of the surfaces against damage of various types. Tribological properties of the third body greatly depend on the initial properties of its component elements and features of the contact zone. The sliding velocity, power and thermal loading, and the sliding distance have especially great influence on the destruction of the third body. For providing the stability of the third body in the contact zone of the wheels and rails and reduction of the derailment probability, energy consumed on traction, environment pollution, and maintenance expenses, the decrease of the sliding distance and relative sliding

The wheel/rail squeal in curves is the most common type of vibrations and noise. It is especially typical for high-speed movements, when because of various reasons, the relative sliding and sliding distance increase. This contributes destruction of the third body, seizure of the surfaces at direct contact, subsequent destruction of the seized surfaces, and instability of the friction forces and relative movement of

Many negative phenomena (wear, noise, vibrations) are generated because of the wheel sliding on the rail. For elimination of the wheel sliding in the curves, the wheel tread surface is given a conical form with the intention of making the outer wheel to roll on the greater diameter passing the greater distance than the inner wheel and rotate both wheels through the equal angles, maintaining this way radial position of the wheelset axle. However, this intention can be realized only for a

influencing them [7, 8].

Transportation Systems Analysis and Assessment

sources of vibrations and noise.

interaction of the wheel and rail [9].

is especially important.

surfaces.

210

$$
\mathfrak{q} = 2 \,\text{l}\Delta\text{R/DR}.\tag{3}
$$

Figure 5. Movement of the wagon wheelset in the curve and wheelset shaft slope from the radial position.

On the other hand, the maximum angle of twist of the wheelset axle φmax depends on the friction force

$$\mathbf{F} = \mathbf{f} \mathbf{Q} \tag{4}$$

and is calculated by the known, from the resistance of materials, formula

$$
\mathfrak{q}\_{\text{max}} = \mathbf{ML} / \mathbf{I}\_{\text{P}} \mathbf{G},\tag{5}
$$

where M is a torque caused by the friction force

$$\mathbf{M} = \mathbf{F} \mathbf{D} / 2 = \mathbf{f} \mathbf{Q} \mathbf{D} / 2; \tag{6}$$

f, friction coefficient; Q, vertical load (half of the load on the wheelset) of the wheel on the rail; L, length of the wheelset axle; Ip, polar moment of inertia of the wheelset axle cross section; and G, modulus of rigidity (share modulus) of the axle material.

We determine distance between the worn-out segments of the rail or path l (at traveling this path, the wheels are rolling on the rail without sliding), at rolling of which the axle is twisted on the maximum angle φmax, from (3) replacing φ by φmax

$$\text{I} = \text{DR } \mathfrak{q}\_{\text{max}} / 2\Delta\text{R} = \text{MLDR} / 2\text{I}\_{\text{P}} \text{G} \Delta\text{R} \tag{7}$$

and putting the found l into (2) we obtain difference of the paths passed by the outer and inner wheels at which the axle is twisted on the maximum angle φmax

$$
\Delta \mathbf{l} = \mathbf{M} \mathbf{L} \mathbf{D} / 2 \mathbf{I}\_{\mathbf{P}} \mathbf{G}.\tag{8}
$$

At one revolution, these wheels will pass the different distances, correspondingly l and l + Δl, deflecting the wheelset axle from its perpendicular position relative to the rail track (Figure 6a). However, in the wagon wheelset the axle being constraint to retain perpendicular position, the wheel with diameter D is forced to pass the same (greater) distance l + Δl and rotate relative to the elliptical wheel in the clockwise direction if it is seen from axial direction A. At that, the wheelset axle

Movement of the free wheelset in the straight rail track: (a) with the wheels of different diameters or with one

The difference of distances passed by the wheels at one revolution is Δl=L–πD,

The distance l at passing of which the wheelset axle will be twisted on the angle

I

In all the three cases considered above, at removing or decrease of the torque M acting on the wheel that takes place at its vertical vibrations when the friction force F decreases, the angle of twist of the axle will start to decrease. Suppose φmax falls down to zero during time t. This will take place at rotation of the inner wheel in the clockwise direction relative to the outer wheel on the angle φmax since the flange of the outer wheel is pressed on the rail and the friction force arisen between the flange and rail additionally restricts its movement. Obviously, during this time t the

l ¼ πDΔl

L ¼ π½ � 3 að Þ� þ b ð Þ 3a þ b ð Þ a þ 3b (10)

Δl ¼ π½3 að Þ� þ b ð Þ 3a þ b ð Þ a þ 3b � � πD (11)

I ¼ φmax D=2 ¼ MLD=2IpG (12)

=Δ (13)

I corresponding to maximum angle of twist φmax is obtained con-

is twisted through angle φ that is determined by formula (1).

Influence of Tribological Parameters on the Railway Wheel Derailment

DOI: http://dx.doi.org/10.5772/intechopen.89135

Δl

where the length of the elliptical tread surface

elliptical wheel; (b) parameters of ellipticity.

or

Figure 6.

The value Δl

sidering formula (5)

φmax will be then

213

### 3.2. Movement of the wagon wheelset with the wheels of different diameters in the straight rail track

At rolling of the free wheelset (without bogie) with the wheels of different diameters D and D + ΔD in the straight rail track the distance l, the greater wheel passes a greater distance l + Δl, deflecting the wheelset axle from its perpendicular position relative to the rail track (Figure 2a). But in the wagon wheelset the axle being constraint to retain perpendicular position, the smaller wheel is forced to pass the same distance l + Δl and rotate relative to the greater wheel in the clockwise direction, if it is seen from axial direction A. At that, the wheelset axle is twisted through angle φ that is determined by formula (1), from where, considering (5), we obtain the value of Δl (see formula (8)) corresponding to the maximum angle of twist φmax.

The following proportion can be written from the drawing: (l + Δl)/l = (D + ΔD)/D or Δl/l = ΔD/D, from which we obtain distance l between the worn-out segments at passing of which the wheelset axle will be twisted through angle φmax:

$$\text{l} = \Delta \text{lD} / \Delta \text{D} = \text{MLD}^2 / 2 \text{I}\_\text{P} \text{G} \Delta \text{D} \tag{9}$$

### 3.3. Movement of the wagon wheelset with one elliptical wheel in the straight rail track

Consider a free wheelset with one wheel of diameter D and other elliptical wheel with the small D and bigger D + ΔD diameters moving in the straight rail track (Figure 6a and b).

Influence of Tribological Parameters on the Railway Wheel Derailment DOI: http://dx.doi.org/10.5772/intechopen.89135

#### Figure 6.

On the other hand, the maximum angle of twist of the wheelset axle φmax

and is calculated by the known, from the resistance of materials, formula

f, friction coefficient; Q, vertical load (half of the load on the wheelset) of the wheel on the rail; L, length of the wheelset axle; Ip, polar moment of inertia of the wheelset axle cross section; and G, modulus of rigidity (share modulus) of the axle

We determine distance between the worn-out segments of the rail or path l (at traveling this path, the wheels are rolling on the rail without sliding), at rolling of which the axle is twisted on the maximum angle φmax, from (3) replacing φ by

and putting the found l into (2) we obtain difference of the paths passed by the outer and inner wheels at which the axle is twisted on the maximum angle φmax

3.2. Movement of the wagon wheelset with the wheels of different diameters

At rolling of the free wheelset (without bogie) with the wheels of different diameters D and D + ΔD in the straight rail track the distance l, the greater wheel passes a greater distance l + Δl, deflecting the wheelset axle from its perpendicular position relative to the rail track (Figure 2a). But in the wagon wheelset the axle being constraint to retain perpendicular position, the smaller wheel is forced to pass the same distance l + Δl and rotate relative to the greater wheel in the clockwise direction, if it is seen from axial direction A. At that, the wheelset axle is twisted through angle φ that is determined by formula (1), from where, considering (5), we obtain the value of Δl (see formula (8)) corresponding to the maximum angle of

The following proportion can be written from the drawing: (l + Δl)/l = (D + ΔD)/D or Δl/l = ΔD/D, from which we obtain distance l between the worn-out segments at passing of which the wheelset axle will be twisted through angle φmax:

l ¼ ΔlD=ΔD ¼ MLD2

3.3. Movement of the wagon wheelset with one elliptical wheel in the straight

with the small D and bigger D + ΔD diameters moving in the straight rail track

Consider a free wheelset with one wheel of diameter D and other elliptical wheel

where M is a torque caused by the friction force

F ¼ fQ (4)

φmax ¼ ML=IpG, (5)

M ¼ FD=2 ¼ fQD=2; (6)

l ¼ DR φmax=2ΔR ¼ MLDR=2IpGΔR (7)

Δl ¼ MLD=2IpG: (8)

=2IpGΔD (9)

depends on the friction force

Transportation Systems Analysis and Assessment

in the straight rail track

material.

φmax

twist φmax.

rail track

(Figure 6a and b).

212

Movement of the free wheelset in the straight rail track: (a) with the wheels of different diameters or with one elliptical wheel; (b) parameters of ellipticity.

At one revolution, these wheels will pass the different distances, correspondingly l and l + Δl, deflecting the wheelset axle from its perpendicular position relative to the rail track (Figure 6a). However, in the wagon wheelset the axle being constraint to retain perpendicular position, the wheel with diameter D is forced to pass the same (greater) distance l + Δl and rotate relative to the elliptical wheel in the clockwise direction if it is seen from axial direction A. At that, the wheelset axle is twisted through angle φ that is determined by formula (1).

The difference of distances passed by the wheels at one revolution is Δl=L–πD, where the length of the elliptical tread surface

$$\mathbf{L} = \pi[\mathbf{3(a+b)} - (\mathbf{3a+b})(\mathbf{a+3b})] \tag{10}$$

or

$$
\Delta \mathbf{l} = \pi [\mathbf{\hat{3}}(\mathbf{a} + \mathbf{b}) - (\mathbf{\hat{3}a} + \mathbf{b})(\mathbf{a} + \mathbf{\hat{3}b})] - \pi \mathbf{D} \tag{11}
$$

The value Δl I corresponding to maximum angle of twist φmax is obtained considering formula (5)

$$
\Delta \mathbf{l}^1 = \varrho\_{\text{max}} \,\mathrm{D}/2 = \mathrm{MLD}/2\mathrm{I}\_\mathrm{P} \,\mathrm{G} \tag{12}
$$

The distance l at passing of which the wheelset axle will be twisted on the angle φmax will be then

$$\mathbf{l} = \pi \mathbf{D} \Delta \mathbf{l}^{\mathrm{l}} / \Delta \tag{13}$$

In all the three cases considered above, at removing or decrease of the torque M acting on the wheel that takes place at its vertical vibrations when the friction force F decreases, the angle of twist of the axle will start to decrease. Suppose φmax falls down to zero during time t. This will take place at rotation of the inner wheel in the clockwise direction relative to the outer wheel on the angle φmax since the flange of the outer wheel is pressed on the rail and the friction force arisen between the flange and rail additionally restricts its movement. Obviously, during this time t the inner wheel will roll and slide simultaneously on the rail and the rolling and sliding distance on the rail will be

$$\mathbf{S}\_{\mathbf{r}} = \mathbf{V}\mathbf{t} \tag{14}$$

We note that the rolling and sliding distance on the wheel tread surface is

$$\mathbf{S}\_{\mathbf{w}} = \Delta \mathbf{l} + \mathbf{S}\_{\mathbf{r}}.\tag{14'}$$

or for the variant of the elliptical wheel

$$\mathbf{S}\_{\mathbf{w}} = \Delta \mathbf{l}^{\mathrm{l}} + \mathbf{S}\_{\mathbf{r}} \tag{15}$$

here Δl or ΔlI is a sliding friction path and the wavelength of the worn-out rail (Figure 3)

$$\mathbf{W} = \mathbf{l} \mathbf{s}\_{\text{ers}} \tag{16}$$

We note that maximum velocity of the wheel contact point relative to the wheel

where A = φmax is an amplitude of the wheelset shaft torsion vibrations and ω =

� 100% and Kw ¼ Vsl

where i is the wear intensity and N, number of cycles which is determined as

where N1 is a number of the trains passing by a day; N2, number of wagons in the train; N3, number of wheels on one side of the wagon; and N4, number of days

Possibility of derailment or the wheel's rolling up on the rail is estimated by the criterion of the wheel flange contact point (point A, Figure 9) slipping down the rail lateral surface, based on the condition of equilibrium of forces acting on this point [24]. Lateral L and vertical V forces determined from the condition of equilibrium of these forces are.where N is a normal force; FI = fIN, friction force

The depth of the worn-out layer a year of the rail segment Sr.

ffiffiffi C I r

Vw

� D

Vsl ¼ Vw–Vr (21)

h ¼ iΔlN (23)

N ¼ N1N2N3N4 (24)

2 þ Vr (20)

� 100% (22)

2 þ Vr ¼�φmax

center.

Figure 8.

ffiffiffiffiffiffiffiffi

follows:

a year.

215

Sliding velocity

VI

The rolling and sliding distances on the rail and wheel.

DOI: http://dx.doi.org/10.5772/intechopen.89135

C=I p is cyclic frequency of vibrations.

Relative sliding velocities

4. Conditions of derailment

w ¼� AωD

Influence of Tribological Parameters on the Railway Wheel Derailment

Kr ¼ Vsl Vr

This value of the wavelength assumes that at release of the inner wheel, the friction force acting on it from the rail is zero. When the friction force differs from zero, the wavelength will be less since its both components will decrease and its value depends on the friction force magnitude.

To determine time t, we present the wheelset as a one-mass torsional vibratory system (Figure 7a), where C is a torsional rigidity of the wheelset axle and I, total moment of inertia of the inner wheel. Then, angle of twist φmax will fall down to zero in conformity with a law of free vibrations of this vibratory system during the period P/4 (Figure 7b).

At that, period of free vibrations

$$\mathbf{P} = 2\pi\sqrt{I/\mathbf{C}} \tag{17}$$

and consequently, time t will be

$$\mathbf{t} = \mathbf{P}/\mathbf{4} = \frac{\pi}{2}\sqrt{I/\mathbf{C}}\tag{18}$$

The average velocity of the wheel contact point relative to the wheel center (Figure 8)

$$\mathbf{Vw} = -\frac{D\mathbf{q}\max}{\mathbf{2}t} + \mathbf{Vr} \tag{19}$$

where Vr = � V is a velocity of the rail contact point relative to the wheel center.

Figure 7. (a) One-mass torsional vibratory system; (b) graph of the system free vibrations.

Influence of Tribological Parameters on the Railway Wheel Derailment DOI: http://dx.doi.org/10.5772/intechopen.89135

Figure 8. The rolling and sliding distances on the rail and wheel.

We note that maximum velocity of the wheel contact point relative to the wheel center.

$$\mathbf{V}\_w^I = -\frac{A\alpha D}{2} + \mathbf{Vr} = -q\text{max}\sqrt{\frac{\mathbf{C}}{I}} \times \frac{\mathbf{D}}{2} + \mathbf{Vr} \tag{20}$$

where A = φmax is an amplitude of the wheelset shaft torsion vibrations and ω = ffiffiffiffiffiffiffiffi C=I p is cyclic frequency of vibrations.

Sliding velocity

inner wheel will roll and slide simultaneously on the rail and the rolling and sliding

We note that the rolling and sliding distance on the wheel tread surface is

Sw ¼ Δl

here Δl or ΔlI is a sliding friction path and the wavelength of the worn-out rail

This value of the wavelength assumes that at release of the inner wheel, the friction force acting on it from the rail is zero. When the friction force differs from zero, the wavelength will be less since its both components will decrease and its

To determine time t, we present the wheelset as a one-mass torsional vibratory system (Figure 7a), where C is a torsional rigidity of the wheelset axle and I, total moment of inertia of the inner wheel. Then, angle of twist φmax will fall down to zero in conformity with a law of free vibrations of this vibratory system during the

P ¼ 2π ffiffiffiffiffiffiffiffi

2

where Vr = � V is a velocity of the rail contact point relative to the wheel center.

ffiffiffiffiffiffiffiffi

t ¼ P=4 ¼ π

Vw ¼� Dφmax 2t

(a) One-mass torsional vibratory system; (b) graph of the system free vibrations.

The average velocity of the wheel contact point relative to the wheel center

Sr ¼ Vt (14)

Sw ¼ Δl þ Sr: 140 ð Þ

W ¼ lasers (16)

I=C p (17)

I=C p (18)

þ Vr (19)

I þ Sr (15)

distance on the rail will be

(Figure 3)

period P/4 (Figure 7b).

(Figure 8)

Figure 7.

214

or for the variant of the elliptical wheel

Transportation Systems Analysis and Assessment

value depends on the friction force magnitude.

At that, period of free vibrations

and consequently, time t will be

$$\mathbf{V}\mathbf{sl} = \mathbf{V}\mathbf{w} - \mathbf{V}\mathbf{r} \tag{21}$$

Relative sliding velocities

$$\text{Kr} = \frac{V\_{sl}}{V\_r} \times 100\text{\% and Kw} = \frac{V\_{sl}}{V\_w} \times 100\text{\%} \tag{22}$$

The depth of the worn-out layer a year of the rail segment Sr.

$$\mathbf{h} = \mathbf{i}\Delta \mathbf{l} \mathbf{N} \tag{23}$$

where i is the wear intensity and N, number of cycles which is determined as follows:

$$\mathbf{N} = \mathbf{N}\mathbf{1}\mathbf{N}\mathbf{2}\mathbf{N}\mathbf{3}\mathbf{N}\mathbf{4}\tag{24}$$

where N1 is a number of the trains passing by a day; N2, number of wagons in the train; N3, number of wheels on one side of the wagon; and N4, number of days a year.

#### 4. Conditions of derailment

Possibility of derailment or the wheel's rolling up on the rail is estimated by the criterion of the wheel flange contact point (point A, Figure 9) slipping down the rail lateral surface, based on the condition of equilibrium of forces acting on this point [24]. Lateral L and vertical V forces determined from the condition of equilibrium of these forces are.where N is a normal force; FI = fIN, friction force

between the wheel flange and rail lateral surface; fI, friction coefficient between these surfaces; and β, angle of inclination of the wheel flange.

$$\mathbf{L} = \mathbf{N}\sin\beta - \mathbf{F}\mathbf{I}\cos\beta\tag{25}$$

Therefore, it is necessary to provide the criterion (27) with additional condition of impossibility of the wheel rolling on the contact point A, which, on the base of

where h is the value of the climbing advance; r is the radius of the wheel rolling

where f and fI are friction coefficients between the wheel and rail tread surfaces

Determining N and V correspondingly from (25) and (26), substituting them into (29) and then putting obtained P into (28), from the latter we obtain the

h sin β � f

If this criterion is not satisfied, the wheel starts to roll on the contact point A, and the contact between the wheel and rail tread surfaces is lost, or two-point contact at O and A passes into one-point contact at A. For obtaining a criterion of impossibility of the wheel rolling on the contact point A, it is necessary to put f = 0

h sin β � f

ð Þ r þ d f cos β þ f f I

I cos β

I cos β

ð Þ r þ d f

The criteria (30) and (31) provide both, the wheel flange contact point sliding down the rail lateral surface and impossibility of the wheel rolling on this point. Besides, the criterion (30) ensures less value (more conservative) of the allowable ratio of the lateral and vertical forces L/V than criterion (27), while criterion (31), depending on the value of the climbing advance h, gives the ratio L/V less or more than criterion (27). For illustration, consider two variants of numerical data of the

Allowable maximum ratios L/V for these variants calculated by the criteria (27),

Variant Criterion (27) Criterion (30) Criterion (31) a 1.39 0.31 1.04 b 1.39 0.44 1.47

Force P acting on the wheel axle cannot exceed the sum of the friction forces between the wheel and rail tread surfaces and between the wheel flange and rail

circle; d is the vertical coordinate of the contact point A.

Influence of Tribological Parameters on the Railway Wheel Derailment

and the wheel flange and rail lateral surfaces correspondingly.

L V ≤

a. β = 60o; f = 0.4; fI =0.1; h = 62 mm and r + d = 485 mm;

b. β = 60o; f = 0.4; fI =0.1; h = 88 mm and r + d = 482 mm.

(30), and (31) are given in the following table:

following criterion of impossibility of the derailment:

L V ≤ Vh≥ P rð Þ þ d (28)

P≤F þ FI ¼ fV þ fIN (29)

sin β þ f I (30)

I (31)

Figure 10, can be written as

DOI: http://dx.doi.org/10.5772/intechopen.89135

lateral surface:

in (30), which gives.

parameters:

217

$$\mathbf{V} = \mathbf{N}\cos\beta + \mathbf{F}\mathbf{I}\sin\beta\tag{26}$$

It should be noted that the forces acting on point A are interdependent and equalities (25) and (26) are only valid for limited values of forces L and V, since the rise of the friction force FI is limited by the friction coefficient fI. Therefore, at a certain ratio of forces L and V, the friction force FI can no longer balance the contact point A, which will slip down on the rail lateral surface, and it is considered on this ground that the wheel cannot roll up on the rail. At that, equalities (25) and (26) become inequalities from where a criterion of impossibility of the wheel rolling up on the rail or derailment is obtained [24]:

$$\frac{L}{V} \le \frac{\tan \beta - f^I}{1 + f^I \tan \beta} \tag{27}$$

However, at sign of equality (=) in (27) and to a certain extent at sign of inequality (<) also, the wheel can rotate about contact point A and roll up on the rail if such possibility exists or if moment of the force P acting on the wheel axle exceeds the moment of the vertical force V about contact point A (Figure 10). In other words, under such condition, two-point (O, A) contact of the wheel passes into one-point contact at A. In the first case (at sign =), the wheel will roll on the immobile point A with pure rolling, and in the second case (at sign <), the wheel will roll on the mobile point A creeping slowly down the rail lateral surface with combined rolling and sliding. Both cases lead to the wheel climbing the rail and derailment.

Figure 10. Forces acting on the wheel axle.

Influence of Tribological Parameters on the Railway Wheel Derailment DOI: http://dx.doi.org/10.5772/intechopen.89135

Therefore, it is necessary to provide the criterion (27) with additional condition of impossibility of the wheel rolling on the contact point A, which, on the base of Figure 10, can be written as

$$\mathbf{Vh} \ge \mathbf{P}(\mathbf{r} + \mathbf{d}) \tag{28}$$

where h is the value of the climbing advance; r is the radius of the wheel rolling circle; d is the vertical coordinate of the contact point A.

Force P acting on the wheel axle cannot exceed the sum of the friction forces between the wheel and rail tread surfaces and between the wheel flange and rail lateral surface:

$$\mathbf{P} \le \mathbf{F} + \mathbf{F}\mathbf{I} = \mathbf{f}\mathbf{V} + \mathbf{f}\mathbf{I}\mathbf{N} \tag{29}$$

where f and fI are friction coefficients between the wheel and rail tread surfaces and the wheel flange and rail lateral surfaces correspondingly.

Determining N and V correspondingly from (25) and (26), substituting them into (29) and then putting obtained P into (28), from the latter we obtain the following criterion of impossibility of the derailment:

$$\frac{L}{V} \le \frac{h\left(\sin\beta - f^l \cos\beta\right)}{(r+d)\left(f\cos\beta + ff^l\sin\beta + f^l\right)}\tag{30}$$

If this criterion is not satisfied, the wheel starts to roll on the contact point A, and the contact between the wheel and rail tread surfaces is lost, or two-point contact at O and A passes into one-point contact at A. For obtaining a criterion of impossibility of the wheel rolling on the contact point A, it is necessary to put f = 0 in (30), which gives.

$$\frac{L}{V} \le \frac{h\left(\sin\beta - f^I \cos\beta\right)}{(r+d)f^I} \tag{31}$$

The criteria (30) and (31) provide both, the wheel flange contact point sliding down the rail lateral surface and impossibility of the wheel rolling on this point. Besides, the criterion (30) ensures less value (more conservative) of the allowable ratio of the lateral and vertical forces L/V than criterion (27), while criterion (31), depending on the value of the climbing advance h, gives the ratio L/V less or more than criterion (27). For illustration, consider two variants of numerical data of the parameters:

a. β = 60o; f = 0.4; fI =0.1; h = 62 mm and r + d = 485 mm;

b. β = 60o; f = 0.4; fI =0.1; h = 88 mm and r + d = 482 mm.

Allowable maximum ratios L/V for these variants calculated by the criteria (27), (30), and (31) are given in the following table:

between the wheel flange and rail lateral surface; fI, friction coefficient between

It should be noted that the forces acting on point A are interdependent and equalities (25) and (26) are only valid for limited values of forces L and V, since the rise of the friction force FI is limited by the friction coefficient fI. Therefore, at a certain ratio of forces L and V, the friction force FI can no longer balance the contact point A, which will slip down on the rail lateral surface, and it is considered on this ground that the wheel cannot roll up on the rail. At that, equalities (25) and (26) become inequalities from where a criterion of impossibility of the wheel rolling

tan β � f

1 þ f

However, at sign of equality (=) in (27) and to a certain extent at sign of inequality (<) also, the wheel can rotate about contact point A and roll up on the rail if such possibility exists or if moment of the force P acting on the wheel axle exceeds the moment of the vertical force V about contact point A (Figure 10). In other words, under such condition, two-point (O, A) contact of the wheel passes into one-point contact at A. In the first case (at sign =), the wheel will roll on the immobile point A with pure rolling, and in the second case (at sign <), the wheel will roll on the mobile point A creeping slowly down the rail lateral surface with combined rolling and sliding. Both cases lead to the wheel climbing the rail and

I

L V ≤

L ¼ N sin β � FI cos β (25) V ¼ N cos β þ FI sin β (26)

I tan β (27)

these surfaces; and β, angle of inclination of the wheel flange.

up on the rail or derailment is obtained [24]:

Transportation Systems Analysis and Assessment

derailment.

Figure 9.

Figure 10.

216

Forces acting on the wheel axle.

Forces acting on the contact point a.

For analysis of the obtained results, suppose that ratio L/V = 1.3, i.e., criterion (27) is satisfied and derailment is not possible. However, it is seen from the table that for variant (a) neither criteria (30) nor (31) are satisfied and both predict derailment. For variant (b), criterion (30) is not satisfied, or it predicts derailment, and criterion (31) is satisfied, i.e., by this criterion, derailment is not possible. This means that the wheel starts to roll on the contact point A and two-point (O, A) contact passes into one-point contact at A. Then, this contact point slides down the rail lateral surface, the two-point contact restores, and so on, this process is repeated. However, at passing from two-point (O, A) contact into one-point contact at A, the lateral and vertical forces on the steering surfaces increase. Typical for these surfaces, increased relative sliding increases the power and thermal loads in the contact of these surfaces, generating the convenient conditions for destruction of the third body. This results in sharp increase of the cohesion forces, scuffing, and friction coefficient that promotes climbing of the wheel flange on the rail lateral surface. This is confirmed by the numerous laboratory researches carried out by us as well as the trace of the wheel climbing on the railhead lateral surface (Figure 1) that has a form of scuffing.

less value (more conservative) of the allowable ratio of lateral and vertical

For solution of the problem of derailment, an experimental–theoretical approach

Due to the existence of materials with quite different designations and properties in the contact zone, many new unanswered problems rise. They are related with the further increase of the derailment criterion informativity and precision, providing the contact zone with the third body having due properties, conditions of formation, and destruction of the third body. They also concern to the tribological properties of the interacting metal and nonmetal surfaces, direct interaction of their juvenile surfaces and generation of the strong adhesion bonds, cold welding, destruction and wear of the surfaces, variation of the value, and instability of the

On the base of experimental researches, we have ascertained dependence of the friction coefficient on the degree of destruction of the third body for the conditions of various relative sliding velocities, speeds, materials of interacting surfaces, roughness of the surfaces, friction modifiers, and loads at which the range of variation of the acting parameters is quite wide and therefore continuation of

George Tumanishvili\*, Tengiz Nadiradze and Giorgi Tumanishvili

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*Address all correspondence to<EMAIL_ADDRESS>
Institute of Machine Mechanics, Tbilisi, Georgia

provided the original work is properly cited.

is needed because of the lack of comprehensive theoretical model of the wheel

Influence of Tribological Parameters on the Railway Wheel Derailment

forces than Nadal's formula.

DOI: http://dx.doi.org/10.5772/intechopen.89135

climbing on the rail.

friction coefficient.

researches is needed.

Author details

219

Thus, it is expedient to estimate possibility of derailment by criterion (30), since it provides both, the wheel flange contact point sliding down the rail lateral surface and impossibility of the wheel rolling on the same point, and ensures less value (more conservative) of the allowable ratio of the lateral and vertical forces L/V than criteria (31) and (27).


**Hematopoietic Stem Cell in Acute Myeloid Leukemia Development**

Sérgio Paulo Bydlowski and Felipe de Lara Janz *University of Sao Paulo School of Medicine Laboratory of Genetics and Molecular Hematology, São Paulo, SP, Brazil*

### **1. Introduction**

260 Advances in Hematopoietic Stem Cell Research

Yilmaz, O.H., Kiel, M.J., and Morrison, S.J. (2006). SLAM family markers are conserved

Zeggini, E., Scott, L.J., Saxena, R., Voight, B.F., Marchini, J.L., Hu, T., de Bakker, P.I.,

increase their purity. Blood *107*, 924-930.

loci for type 2 diabetes. Nat Genet *40*, 638-645.

among hematopoietic stem cells from old and reconstituted mice and markedly

Abecasis, G.R., Almgren, P., Andersen, G.*, et al.* (2008). Meta-analysis of genomewide association data and large-scale replication identifies additional susceptibility

> Hematopoietic stem cells (HSCs) are multipotent stem cells defined by their ability to selfrenewal, differentiation and maintenance of all blood cell types in the hematological system during the entire lifetime of the organism. This physiological process, called hematopoiesis, is controlled by several complex interactions between genetic processes in blood progenitor cells and bone marrow microenvironment. Hemostasis is maintained by a delicate balance between processes such as self-renewal, proliferation and differentiation versus apoptosis and cell-cycle arrest in HSCs. Over the last two decades, several studies have been made to understand possible mechanisms of cell malignancy and tumor growth, both in solid and hematological cancers. Leukemias are hematological malignancies that arise from cancer stem cells (CSCs). Neoplastic transformation of hematopoietic stem or progenitor cells occurs by unbalanced critical mechanisms. Blood cancers, as acute myeloid leukemia (AML), are sustained by leukemic stem cells (LSCs) which, like normal HSCs, present a range of biological characteristics that enable their long-term survival. AML is a well studied hematological cancer type characterized by an accumulation of clonal myeloid progenitor cells that do not differentiate normally. However, there is still no consensus about the mechanisms by which the HSCs transformation occurs. In this chapter, the hematopoietic stem cells and leukemic stem cells will be focused on leukemia development, mainly in AML.


*3.2. Catalytic Activity Test*

The catalytic activity test was carried out in a fixed-bed continuous flow micro-quartztube reactor with 10 mm in diameter at atmospheric pressure. There was a thermocouple near the reactor close to the fixed-bed, which was used to follow the temperature of the catalysts during the test. Before the activity test, 0.50 g of the catalyst was heated up to 450 ◦C (10 ◦C/min) and then reduced at a constant temperature of 450 ◦C for 1 h in H2/Ar (F(H2) = F(Ar) = 30 mL/min) mixture gas. After that, the catalyst was cooled down to the reaction temperature before the introduction of the mixture of reactants (H2/CO2 = 4, F = 150 mL/min) for the CO2 methanation reaction. The effluent from the reactor passed through a condensing device and was analyzed online by a gas chromatograph (plot-C2000 capillary column) per hour.

$$X\_{CO\_2} = \frac{n\_{CO\_2,in} - n\_{CO\_2,out}}{n\_{CO\_2,in}} \times 100\%\_{\prime} \tag{1}$$

$$X\_{H\_2} = \frac{n\_{H\_2,in} - n\_{H\_2,out}}{n\_{H\_2,in}} \times 100\% \tag{2}$$

$$S\_{CH\_4} = \frac{n\_{CH\_4,our}}{n\_{CH\_4,our} + n\_{CO,our}} \times 100\%,\tag{3}$$

$$Y\_{CH\_4} = X\_{H\_2} \times S\_{CH\_4} \tag{4}$$

where *XCO*2 and *XH*2 were the conversion of *CO*2 and *H*2, *SCH*4 was the selectivity of *CH*4, and *YCH*4 was the yield of *CH*4.

#### *3.3. Catalysts Characterization*

The physical property test was conducted in the Micromeritics Tristar II 3020 instrument by using the N2 adsorption-desorption method. Before the measurements, about 0.1 g samples were outgassed at 150 ◦C for 2 h and then at 300 ◦C for 2 h under a vacuum.

The actual Ni and Si loadings of the fresh catalysts were determined by the X-ray fluorescence (XRF) test. Ni and Si were detected by the Ni Kα line and Si Kα line, respectively.

The hydrogen temperature-programmed reduction (H2-TPR) measurement was carried out with a Micromeritics AutoChem II Chemisorption Analyzer. At first, about 100 mg of the catalyst was pretreated with Ar flow at 150 ◦C for 30 min. Then, the TPR experiment was performed from 50 to 800 ◦C in the H2/Ar (10/90 vol%) flow with the heating rate of 8 ◦C/min. The TCD detector was used to monitor the H2 consumption.

The temperature-programmed desorption of H2 (H2-TPD) was performed on the same equipment for H2-TPR. About 100 mg of the reduced catalyst was pretreated at 500 ◦C for 1 h in Ar flow. Next, H2 was absorbed at 50 ◦C for 1 h in 10% H2/Ar. After cleaning the excess unabsorbed H2, the catalyst was heated to 800 ◦C with a heating rate of 10 ◦C /min under Ar flow. The results were detected by a TCD detector. The H2 pulse chemisorption was also processed on the equipment. About 100 mg of the reduced catalyst was pretreated at 450 ◦C for 1 h in Ar flow and cooled down to 50 ◦C at the same atmosphere for beginning the H2 adsorption. A gas mixture of 10% H2 balance Ar was pulsed over the catalyst for chemisorption measurements.

Before the temperature-programmed desorption of CO2 (CO2-TPD), about 100 mg of the reduced catalyst (reduced at 450 ◦C) was pretreated at 500 ◦C in He flow for 1 h to remove surface impurities. Then, CO2 was absorbed at 50 ◦C for 1 h in 10% CO2/He. After cleaning the excess unabsorbed CO2, the catalyst was heated to 900 ◦C with a heating rate of 10 ◦C/min in He flow. The observed curves were fitted into two Gaussian peaks.

The X-ray diffraction (XRD) was performed on a DX-1000 CSC diffractometer instrument, operating at 40 kV and 25 mA with a Cu Kα radiation source for the calcined and reduced catalysts. The data was recorded over the scattering angle range of 2θ from 10 to 80◦, with a scan step with of 0.03◦.

Transmission electron microscopy (TEM) was used to characterize the reduced catalysts on the Tecnai G2 F20 machine. The twin instrument with the 0.20 nm resolution was used, and the acceleration voltage was 200 Kv.

The analysis of X-ray photoelectron spectroscopy (XPS) was carried out on a KRATOS spectrometer with an AXIS Ultra DLD. The Al Kα monochromatized line was operated at the accelerating power of 25 W. In addition, the binding energy was calibrated with C 1 s 284.6 eV.

Thermogravimetric (TG) and differential scanning calorimetry analysis (DSC) was used to characterize the deposited carbon of the spent Ni-xSi/ZrO2 catalysts, using the NETZSCH TG209F1 instrument. Before the test, the sample was placed until a better gas equilibrium. Then, the temperature was increased from 30 to 800 ◦C with a 5 ◦C·min−1 heating rate in air flow with a rate of 60 mL·min−1.

#### **4. Conclusions**

Adding the appropriate amount of Si could increase the catalytic activity of Ni/ZrO2 catalyst, and the Ni-0.1Si/ZrO2 catalyst showed the highest catalytic activity and stability. The strong interaction between Ni and ZrO2 could promote the dispersion of Ni on the support, and the strong basic sites on the catalyst were beneficial to the absorption of CO2, thus to the CO2 methanation reaction on the Ni-0.1Si/ZrO2 catalyst. In addition, the higher amount of surface Ni0 could provide more active sites, and the more oxygen vacancies were beneficial to the absorption and activation of CO2 on the 0.1Si/ZrO2 catalyst.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/2073-4 344/11/1/67/s1. Figure S1. The TG-DSC profile of the spent Ni-xSi/ZrO2 catalysts (A) Ni /ZrO2 catalyst, (B) Ni-0.1Si/ZrO2 catalyst, (C)Ni-0.5Si/ZrO2 catalyst, and (D) Ni-1Si/ZrO2 catalyst.

**Author Contributions:** Conceptualization, methodology, L.L., Y.W. and C.H.; software, validation, formal analysis, investigation, resources, data curation, writing—original draft preparation, L.L. and Q.Z.; writing—review and editing, visualization, supervision, Y.W. and C.H.; project administration, funding acquisition, C.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the National Key R and D Program of China (2018YFB1501404), the 111 program (B17030), and Fundamental Research Funds for the Central Universities.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** We would like to thank the Analytical and Testing center of Sichuan University for the characterization and we are grateful to Yunfei Tian for his help in the XPS experiments.

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


Options for the Disposal and Reuse of Wastewater Sludge, Associated Benefit, and Environmental Risk

*Astha Kumari, Nityanand Singh Maurya, Abhishek Kumar, Rajanee Kant Yadav and Amit Kumar*

### **Abstract**

To protect human and environmental health, wastewater treatment is one of the important activities in urban and industrial areas. Urbanized increasing population with industrialization demands more amount of wastewater treatment. Despite wastewater treatment's positive impact on human and environmental health, it also produces sludge as a by-product of the process. Characteristics of the sludge mainly depend on the source of wastewater and the process applied for its treatment. Domestic sludge generally contains a large number of pathogenic bacteria carrying biodegradable compounds. Characteristics of industrial sludge vary greatly. It may contain biodegradable, non-biodegradable, toxic compounds, heavy metals, etc. The sludge may be in the form of liquid or semisolid with 0.25–12% solids. Thus, the handling and disposal/reuse of sludge may become a complex task due to its large volume and infectious and/or toxic nature. This chapter analyses the characterization and quantity estimate of the sludge produced during the application of various municipal and industrial wastewater treatment options. Current practices for the disposal and reuse options such as anaerobic digestion for biogas production, composting to utilize as a fertilizer, brick production, filler material, and bioplastic production will be reviewed and the suitability of each option in terms of benefit and risk will be critically analyzed.

**Keywords:** sewage sludge, biogas, bioplastic, anaerobic digestion, sludge reuses

#### **1. Introduction**

Wastewater contains a lot of solid and liquid waste discarded after use and defined in various combinations based on their sources of generation. The wastewaters from residential apartments, colonies, and institutions are termed domestic, wastes from agricultural fields, mining effluents and industrial are termed as industrial wastewater [1].

With the increase in population coupled with urbanization and industrialization, the quantity of wastewater is also increasing. To cater to the increasing demand for water for urban, industrial, and agricultural purposes, the need for its treatment,

call for water reuse, and resource recovery are growing exponentially. Wastewater treatment is one of the important activities in urban and industrial areas in order to protect human and environmental health and to eliminate or neutralize these pollutants. Though wastewater treatment has a positive impact on human and environmental health, it also produces sludge as by-product of the process. The sludge may be in the form of a liquid or a semisolid, with 0.25 to 12% solids that come from households and industries [2]. This sewage sludge may cause various environmental and health problems such as nutrient leaching, loss of soil biodiversity, emission of GHGs, and pathogenic outbreak [2]. Challenges related to managing the sludge thus produced are cost related to handling and transportation, disposal methods, strict regulations, and environmental threats [3]. A clean and sustainable environment can only be built by introducing technologies that are environment friendly and economically feasible. Hence, the treatment of wastewater as per quality standards is no longer the only objective of WWTPs; they also need to focus on its discharge management units. Sewage sludge contains insecticides, cleansing agent, oils, fats, grease, thinners, paints, etc. The high fat content of the sludge may be utilized for biofuel productions such as biodiesel, biohydrogen, bioethanol, and bio-oils [4].

Therefore, the chapter will include the characterization and quantity estimate of the sludge produced during the application of various municipal and industrial wastewater treatment options. Current practices for disposal and reuse options such as anaerobic digestion for biogas production, composting to utilize as fertilizer, brick production, filler materials, or bioplastic production will be reviewed, and the suitability of each option in terms of benefit and risk will be critically analyzed.


*Supporting open minds since 2005*

Vascular Malformations of the Central Nervous System http://dx.doi.org/10.5772/intechopen.78160 Edited by Bora Gürer and Pinar Kuru Bektaşoğlu

#### Contributors

Nissar Shaikh, Amer Jaradat, Sara Abusini, Nour Tashtush, Abdelwahab Aleshawi, Adel. E. Ahmad Ganaw, Abdulgafoor Tharayil, Moad Ehfeda, Ali Ayyad, Nabil Shalik, Dr Nissar Shaikh, Ibrahim Naemi, Mohamed Alfared, Qazi Zeeshan Ul Haq, Hossam Algallie, Sohel Mohamed Gamal Ahmed, Sujith Madambikattil Prabhakaran, Arshad Husain Chanda, Simi Praveen, Ajithkumar Choran, Sedef Tavukçu Özkan, Themistoklis Papasilekas, Konstantinos Themistoklis, Stefanos Korfias, Damianos Sakas, Saar Golan, Amir Arthur, Nitzan Hirsh, David Kieser, Sherry Soltani, Michael Wyatt, Khoon S Lim, Sandra Kieser, Cagin Senturk

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**3. Conclusions**

The pharmacovigilance of biologics undoubtedly presents complexities that are not unique to "conventional drugs." It is an evolving science that will undoubtedly need to be implemented since knowledge about these drugs continues to expand. The peculiarities of these drugs make the monitoring of biologics and biosimilars a real challenge for regulatory agencies, manufacturers, and patients. Specific aspects of these drugs are immunogenicity, differences between batches from different manufacturers, and the definition of similarity and interchangeability or substitutability, all of which are undoubtedly important for the safety and the pharmacovigilance of these drugs [34]. An emblematic example is the number of cases between 1998 and 2004 of pure erythroid aplasia caused by autoantibodies due to a manufacturing modification that increased the immunogenicity of an erythropoiesis-stimulating agent [11, 35]; however, with three similar products on the market, the real challenge was to identify which specific agent was causing the problem [36]. As is well known, the development of biosimilars not only reduces the cost of healthcare by reducing drug costs by 20–30% [37] but also increases the number of marketing authorizations and consequently the access to such therapies, as demonstrated by a study on 21 European countries that showed that the average cost of erythropoietin fell by 35% from 2006 to 2013 [3]. Yet, as highlighted by a recent review [6], healthcare professionals still approach biosimilars with great caution and sometimes stigmatization, and, in particular, are generally opposed to multiple "switches" and interchangeability. Moreover, many treatment discontinuations with biosimilars seem to be linked to the nocebo effect [38]. Clinicians should, however, take into account the principle that no two biologics are identical, even if they are produced by the same manufacturer, as each biologic is different from another in itself [39]; they should also consider that regulations on biosimilars (unlike those on generics) are stringent and rigorous and this in itself is a guarantee (although not a certainty) of high-quality standards. Healthcare professionals and patients should, therefore, have a coherent, comprehensive, and unbiased view of the biosimilar. Still, to do so, their knowledge needs to be updated appropriately through effective and continuous training programs promoted by the various national regulatory agencies. Nevertheless, it is also necessary to collect more and more reassuring data on biologics in general and on interchangeability (and the possible induction of immunogenicity related to it), which is still the central dilemma among clinicians and stakeholders. It is also essential to consider that immunogenicity could be a consequence of several factors, such as the underlying disease, genetic background, age, and immune status, including immunomodulatory therapy, route of administration, dosing schedule, frequency, and duration of treatment, posttranslational modifications, formulation, and impurities. Finally, it is essential to develop educational tools regarding the ADR reporting process for biological products, including the appropriate use of the specific product name and batch number, and reflect on the possibility of making such data more easily accessible to the clinician/or pharmacist.


*What Do We Know about the Diet of Ecuadorian Owls? DOI: http://dx.doi.org/10.5772/intechopen.108594*

light on owls' capture methods or activity schedules. To date, most publications about Ecuadorian owls pertain to *T. furcata*, mirroring the situation of this species in other Neotropical countries [9]. More information on pellets comes from dry areas such as the southwestern tropics and the Andean valleys since pellets are better preserved in dry than in humid environments like the Amazonian rainforests or cloud forests along Andean slopes. Dietary information of humid forest owls reported for Ecuador to date corresponds to less than three pellets [29, 35].

An owl species' diet is often inferred from its bill form and/or knowledge about its congeners. Yet, diets may vary due to factors, such as seasonality, sex, ontogeny, availability of prey, or geography, even in nearby or similar geographical areas, individuals could differ in diet [60]. Therefore, it is important to continue studying and publishing information even about common species like *T. furcata* and *A. cunicularia* (**Figure 4**). On the other hand, since *Megascops roboratus* and *G. nubicola* are regional endemics (i.e., their global distribution ranges are mainly confined to Ecuador [34]), studying them in Ecuador is promising as to obtain natural history information.

Of 29 species of owls present in Ecuador, there are no diet data in the country for two species (*Glaucidium griseiceps* and *Aegolius harrisii*). If we narrow this analysis to the 39 subspecies present, four additional taxa are added to this figure: *Megascops roboratus roboratus, Lophostrix cristata cristata, Strix virgata* cf*. superciliaris*, and *Athene cunicularia carrikeri*. There are only 11 museum specimens with information about stomach contents deposited in Ecuadorian bird collections, all from MECN, that were not studied earlier [23]. Most information in specimen labels, though, is basic and unquantified. Likewise, there are only eight new papers [14, 18, 28, 30, 44, 46, 47, 49] reporting owl species diets since the only state-of-the-art revision by Freile et al. [34].