**5. Conclusions**

The above discussed results elucidate the mechanism of action of cerium oxide coatings as effective cathodes and of cerium ions (when they are present as a component of the corrosion medium) – as inhibitor having oxidative action, leading to improvement of the corrosion stability of stainless steels. They explain the improved ability of the steel to undergo passivation, respectively to recover its passive state in cases of disruption of its surface passive film – especially in this specific case, studied by us, i.e. disruption as a result of thermal treatment.

This effect is associated with a strong shifting of the stationary corrosion potential of the steel in positive direction, moving over from potentials, characteristic of corrosion in active state to potentials, located inside the zone of passivity. In this respect, another basic purpose of the investigations was the elucidation of the mechanism of action of the cerium oxides film and in particular collecting experimental evidence for the supposition about the occurring of an efficient depolarization reaction of CeO2 reduction, resulting in a state of passivity, instead of hydrogen depolarization reaction. For this purpose we considered also the decrease in the surface concentration of Ce in the passive layer under the conditions of the actual corrosion process (self-dissolution) of the stainless steel, by means of XPS, EDS and ICP-AES analyses. A decrease in the surface concentration of CeO2 (Ce4+) has been observed, which is known to be chemically inert in acidic media. The obtained results prove the occurrence of an effective cathodic process of Ce4+ reduction into Ce3+ in the surface oxide film. These results elucidate in details the corrosion behavior of the system Ce2O3- CeO2/steel in 0.1N H2SO4. They explain the improved ability of self-passivation, respectively the restoration of the passive state of the thermally treated steel in the presence of cerium oxides as components of the modified passive surface film.

It has also been shown that the couple Ce4+/Ce3+, as component (inhibitor) of the corrosion medium, displays analogous action. It is expressed in the occurrence of a reaction of reduction of the oxidative component of the medium - Ce4+, leading to consumption of the electrons removed in the course of oxidation, respectively passivation, of the active anodic sections.


**Acknowledgement**

The authors would like to acknowledge the University of Newcastle EM-X-ray Unit and Ms. Jenny Zobec for assistance in obtaining the XRD data. WMD acknowledges the University of Newcastle for the provision of an APA PhD scholarship.


**Acknowledgements**

This research was conducted at the Future Cities Lab Global at ETH Zurich. Future Cities Lab Global is supported and funded by the National Research Foundation, Prime Minister's Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme and ETH Zurich (ETHZ), with additional contributions from the National University of Singapore (NUS), Nanyang Technological University (NTU), Singapore and the Singapore University of Technology and Design (SUTD).


*Article* **Research of Resistance of Selected Materials to Abrasive Wear to Increase the Ploughshare Lifetime**

**Monika Vargova 1,\*, Miroslava Tavodova 1, Katarina Monkova 2,3,\* and Miroslav Dzupon 4**

**Abstract:** Road maintenance and cleaning in winter are performed with ploughshares. Due to the fact that the layer of snow and ice that is removed from the road surface contains various hard impurities, ploughshares are exposed to high intensity abrasive wear. This article deals with the resistance to abrasive wear of originally used ploughshare materials and the materials that were designed as a suitable modification of the ploughshare to increase its service life. The chemical composition of materials used to manufacture ploughshare components is unknown. For this reason, they were analyzed with an ARL 4460 spectrometer, which was used to analyze the element content. The main part of the research was focused on the abrasion resistance test, which was performed according to the GOST 23.208-79 standard. Based on the chemical analysis, it was found that the basic body of the ploughshare was made of S355J2G3 steel, and the raking blade material was made of 37MnSi5 steel. The original material (steel S355J2G3) of the ploughshare body as a reference standard was compared to steel HARDOX 450. Furthermore, a sample made of the original material of the raking blade (steel 37MnSi5) was used as a reference standard, the properties of which were compared to the newly designed OK 84.58 and UTP 690 hardfacing materials. The parametric test method of statistical hypotheses was also used to process and evaluate the weight losses of the selected materials.

**Keywords:** abrasive wear; wear resistance; ploughshare; hardfacing materials; hypothesis testing

#### **1. Introduction**

Forest roads are important in terms of making forests accessible for heavy machinery and timber transportation. Therefore, it is necessary to maintain these roads both in summer and winter. It is necessary to remove a layer of snow or ice from the road surface in the winter time. Snow is removed from the road using a snow ploughshare. Since the removed layer of snow contains various hard impurities, the ploughshares are exposed to high—and especially abrasive—wear and their replacement is relatively economical. Therefore, it is necessary to look for ways to increase their service life and examine their resistance to abrasive wear.

Wear is one of the main factors affecting the performance and lifetime of the components of various mechanisms [1]. Abrasive wear is one of the dominant and common tribological wear processes [2–4] leading to expensive costs for repairing worn mechanisms and replacing spare parts [1]. This wear is characterized by a reduction in the volume of the material and a change in its shape, causing a decrease in work efficiency [5]. Wear caused by shocks and abrasion by hard abrasive particles is a major problem in many industries, especially in agriculture, forestry, mining, mineral processing, etc. [6,7].

**Citation:** Vargova, M.; Tavodova, M.; Monkova, K.; Dzupon, M. Research of Resistance of Selected Materials to Abrasive Wear to Increase the Ploughshare Lifetime. *Metals* **2022**, *12*, 940. https://doi.org/10.3390/ met12060940

Academic Editor: George A. Pantazopoulos

Received: 27 April 2022 Accepted: 26 May 2022 Published: 30 May 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

Abrasive wear occurs when a hard rough surface slides across a softer surface; in this case, wear is defined as damage to a solid surface that generally involves the progressive loss of material and is due to relative motion between that surface and a contacting substance or substances.

The material from grooves is usually removed in the form of loose particles [8–10]. The material resistance against abrasive wear is higher with higher hardness [5,11].

This type of wear is caused by sharp particles that slide or flow over the metal surface at different speeds and pressures, grinding the material from the surface like small cutting tools. The harder the particles and the sharper their shapes, then the more intense the abrasion is. Typical cases of abrasive wear are encountered in earthworks, material transportation and agricultural equipment [12,13].

During abrasive wear, the material is removed from the surface when the stress in it reaches a critical value. This local fracture stress can be achieved by one or more abrasive particles coming into contact with the tool surface. Material that is not removed in this way can be deformed due to abrasion as well as impact [14,15].

One of the very effective measures to increase wear resistance is to protect functional surfaces with a suitable coating material [16]. Hardfacing is a commonly used method to improve the surface properties of agricultural tools, mining components and soil preparation equipment, among others [17]. The alloy is applied to the surface of the base material (usually on low-carbon or medium-carbon steels) by hardfacing in order to increase the hardness and wear resistance without a significant loss in the ductility and toughness of the base material [16,17].

Important factors that determine the resistance to abrasive wear include the hardness, size, shape and intensity of the particles; as well as the hardness, shape, size and number of hard phases and their distribution in the parent metal. Wear resistance increases with the increasing hardness of hard structural components (carbides, borides, etc.) and with their increasing share in the structure [9,12].

The main components of Fe-based alloys are chromium, molybdenum and boron, which make Fe-based alloys resistant to wear. Wang et al. studied the microstructure, hardness and wear resistance of Fe-based alloys by adding the elements ferrotitanium (Fe–Ti), ferromolybdenum (Fe–Mo), ferrovanadium (Fe–V) and graphite, which were applied by the arc welding process. The results showed that the hardness and resistance of the hardfacing metal layer increase with an increasing proportion of Fe-Ti, Fe-V, Fe-Mo and graphite. Their amounts must be controlled in the range of 8–10% graphite, 12–15% Fe-Ti, 10–12% Fe-V and 2–4% Fe-Mo. However, cracks begin to form in the layer of hardfacing metal if the amount of Fe-Mo is more than 5% [18,19].

Xu et al. studied the effect of the carbide type on the resistance to abrasive wear at different sizes and abrasive particle loads. The results showed that M6C carbides showed higher resistance to wear by fine abrasive particles compared to M2C [20].

During impact wear, the material is exposed to impact and high pressure, due to which it deforms or locally breaks—it can even crack. Due to the relatively high working speeds of ploughshare vehicles, it is necessary to protect the ploughshare from the effects of the impact of the ploughshare hitting with a solid obstacle, e.g., ice and abrasion by mineral particles, gravel and stones [9,12].

For this reason, it is necessary to pay attention to the possibilities of increasing the life of the blades and examine their resistance to abrasive wear, which was also the main goal of the authors' long-term research.

Based on the experience and study of already published outputs in the field, the authors tried to bring new solutions to the issue [16,21]. To the best of the authors' knowledge, no relevant studies have yet been published that compare the resistance of a selected combination of materials (37MnSi5, S355JG3 and HARDOX 450 steels, as well as OK 84.58 and UTP 690 hardfacing materials) to abrasive wear. The achieved results will be contributing and applicable not only to ploughshares, construction machines and forest manipulators, but can also be used in the mechanical engineering, civil and mining industries.

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

The ploughshare (Figure 1), the resistance of which to abrasive wear is the subject of our research, is a commonly used tool for modifying forest roads during wintertime. The ploughshare works in a heterogeneous environment, coming into contact with the road and thus with snow, stones, mineral particles, gravel, sand, etc. First, the raking blade comes into contact with the road. It is stressed by the impact of the first contact with the road and with corrosion and abrasion during the raking. In addition, the rest part of the ploughshare is also stressed because the accumulated snow, together with sand and gravel, creates a force on the ploughshare body from the point of pick-up until it is pushed to the side of the road. As a result, wear occurs due to abrasion and corrosion not only on the raking blade but on the entire working part of the ploughshare (weldment).

**Figure 1.** The arrow ploughshare [22].

The basic dimensions of the currently used steel raking blades and their geometry, symmetrically placed in the shape of an arrow on the front part of the tractors, are shown in Figure 2. The values of these basic dimensions, declared by the manufacturer [23], are listed in Table 1.

**Figure 2.** Basic dimension of steel raking blade.

**Table 1.** Basic dimension of steel raking blade [23].

#### *2.1. Materials of Research Samples*

The raking blades of the ploughshares can be attached to the ploughshare body (to the base material of the ploughshare) in two ways:

Due to the rapid wear of the ploughshare and the need for its frequent replacement, the operator of such ploughshares initiated research that would have increased their lifetime and ensured greater efficiency in the use of funds spent on their purchase and replacement.

For the ploughshare that was the subject of the research, the raking blade was attached by a weld, so it can be said that the ploughshare consisted of 3 main parts, namely the basic ploughshare body, the raking blade and the weld (Figure 3a). There is a detail of the raking blade which is that its significant damage due to the heterogeneity of the working environment is visible in Figure 3b.

**Figure 3.** Part of the discarded ploughshare: (**a**)—main parts of the ploughshare; and (**b**)—detail of a raking blade).

The chemical composition of materials used to manufacture ploughshare components is unknown. From this concern, their elemental analyses were carried out using ARL 4460 spectrometer. The results of the chemical analysis of the individual parts of the originally used ploughshare are shown in Table 2.

(**a**) (**b**)

Based on the performed chemical analysis, it is possible to state that:

levers, bolts, etc. The ultimate tensile strength of 37MnSi5 steel is *Rm* = max. The 760 MPa and hardness 217 HBW [25]. The chemical composition of the tested steel, according to the data from the material sheet, is shown in Table 3.

The ploughshare that was the subject of the research worked for 6–8 weeks. After this time, the raking blade of the ploughshare was worn and unusable. The frequent replacement of the raking blades caused economic and technical problems. Due to the fact that the currently used ploughshare was functionally usable only for a short time and did not meet the requirements for the lifetime of this type of product, it was necessary to design a new solution that improved the situation. Based on the authors' own research and practical experience, as well as on the results described in the professional and scientific literature presented in the Introduction, the following options are suggested to increase the lifetime of the ploughshare and thus increase its resistance to abrasive wear (Figure 4):

The first alternative solution was the idea of replacing the original ploughshare with one compact body made of HARDOX material, replacing all three parts of the ploughshare: the ploughshare body, the weld metal, and the raking blade. HARDOX steels are produced in several designs. HARDOX sheets are considered a worldwide standard in the field of abrasion-resistant steel due to their unique combination of hardness and toughness. The hardness of this steel ranges from 400 HBW to 600 HBW. It is available in the form of sheet metal in thicknesses from 0.7 mm to 160 mm but also in the form of tubes and rods [9,26]. HARDOX 450 material is an abrasion-resistant steel with excellent construction properties. The hardness of this steel is 450 HBW, and the yield strength is *Re* = 1100–1300 MPa. HAR-DOX 450 material is a well flexible material that has guaranteed weldability. It provides good abrasion resistance and thus a longer lifetime. It has better wear resistance [27], higher load capacity, and a longer lifetime compared to ordinary steel with the same hardness. It is used in various components and constructions that are subject to wear [9,27,28]. The chemical composition of HARDOX 450 material is shown in Table 3.

The second alternative solution was to apply a new layer in the form of a hardfacing material to the original 37MnSi5 steel of the raking blade part (see Figure 4). Such a sample with OK 84.58 hardfacing material (Figure 5a) was prepared in the company ŽOS Zvolen, a.s. in a single layer by certified welders. The electrode was dried for 2 h at 200 ◦C without

preheating the sample. The applied hardfacing voltage was *U* = 21.5 V and the hardfacing current was *I* = 140 A. The stated parameters were chosen according to the experience of experts from the company.

**Figure 5.** Sample with hardfacing materials; (**a**) OK 84.58; and (**b**) UTP 690.

The OK 84.58 electrode is a high-yield electrode for hardfacing functional surfaces resistant to wear under simultaneous shock stress with the required partial corrosion resistance, used, e.g., for parts of agricultural and forestry machines, mixers, transport equipment, etc. It forms a martensitic structure after hardfacing. It is possible to treat hardfacing materials by grinding [29,30]. The chemical composition of the OK 84.58 electrode is shown in Table 3.

The sample with hardfacing material UTP 690 (Figure 5b), prepared in the company ŽOS Zvolen, a.s. by certified welders, was used as the third alternative solution (see Figure 4). The hardfacing layer was applied to the original 37MnSi5 material of the raking blade part. The electrode was dried for 2 h at 300 ◦C with the preheating of the sample to 230 ◦C. The applied hardfacing voltage was *U* = 21.5 V, and the hardfacing current was *I* = 105 A. In this case, the parameters were also designed according to the experience of the experts from the company.

The UTP 690 electrode is used for the repair and production of cutting tools, especially for the restoration of cutting edges and work surfaces. The coating is highly resistant to friction, compression and impact even at elevated temperatures up to 550 ◦C [31]. Using this electrode, it is also possible to produce new tools by hardfacing on carbon and low-alloyed base steels [31]. This forms a martensitic structure after hardfacing [16]. The chemical composition of the UTP 690 electrode is shown in Table 3.

**Table 3.** Chemical composition of S355J2G3 [24], 37MnSi5 [25], HARDOX 450 [27] steels and OK 84.58 [29] and UTP 690 [31] hardfacing materials according to the datasheets.

All samples, both standard (S355J2G3 and 37MnSi5) and reference ones (HARDOX, OK 84.58 and UTP 690), were prepared according to the GOST 23.208-79 standard by abrasive water jet cutting technology (AWJM), machined by milling and ground by a magnetic surface grinder for obtaining dimensions 30 mm × 30 mm × 10 mm and surface roughness Ra = 0.4 μm (Figure 6). OTTAWA SiO2 silica sand with a grain size of 0.1–0.3 mm was used as an abrasive material [31]. The hardness corresponds to the hardness value according to Vickers 500 HV and Rockwell 54 HRC.

**Figure 6.** Sample for abrasion resistance test with marked dimensions.

#### *2.2. Testing Methods*

There are several methods for testing the wear resistance of materials. Based on the ploughshare operating environment, the method simulating its load in the laboratory conditions at the Technical Faculty of CULS in Prague was chosen. The abrasion resistance test was performed according to standard GOST 23.208-79—Ensuring wear resistance of products. The wear resistance testing of materials by friction against loosely fixed abrasive particles [32].

The principle of the method is to compare the loss of test material and the loss of standard material under the same test conditions. The abrasive material used is electrocorundum with a grain size of 100–250 μm [33] and with a maximum relative mass moisture content of 0.15%. The standard further states that when assessing wear resistance under specific wear conditions, it is permitted to use abrasive material corresponding to the material used during operation but with a maximum grain size of 1.0 mm [32].

Each test sample (standard, test sample) is weighed before the test and placed in the test equipment. Subsequently, the abrasive supply is started, and the rubber disc is pressed against the test sample. A schematic diagram of test equipment for testing the abrasive resistance of materials with a sample ready for testing is shown in Figure 7.

**Figure 7.** Scheme of the test equipment with a test sample [32].

The test equipment Tester T-07, ITC PIB Institution of Technology Radom and the BT-16 Controller (Instytut Technologii Eksploatacji, Radom, PL) used in the presented research are shown in Figure 8b,c, together with the scales (Figure 8a). Three samples were used for each material. After each cycle, the sample was weighed three times on Kern ABS analytical scales with a maximum weight of 120 g and an accuracy of *g* = 1.5 mg. The parameters of the test equipment and samples are shown in Table 4.

**Figure 8.** Abrasion resistance and weight measuring equipment (scales); (**a**)—scales; (**b**)—abrasion resistance equipment; (**c**)—detail of a driving gear with abrasive particles.

**Table 4.** Parameters of the test equipment.

The sample is taken and weighed again after passing the track. Weight loss was calculated as a mean value based on the measurements of each sample.

The hardness coefficient *KT* (-) is calculated from Equation (1) [32] as follows:

$$K\_T = \frac{H}{H\_a} \left(-\right) \tag{1}$$

where *H*—standard material hardness, which is the reference sample (HRC), and *Ha* abrasive hardness (HRC).

The relative abrasion resistance is calculated from Equation (2) [12,32] as follows:

$$
\Psi\_h = \frac{\mathcal{W}\_{h\to}}{\mathcal{W}\_{hPV}} \begin{pmatrix} - \end{pmatrix} \tag{2}
$$

where *WhE*—weight loss standard (g); *WhPV*—a weight loss of the reference sample (g).

#### *2.3. Evaluation Methods*

TESCAN VEGA3 electron microscope (Tescan Orsay Holding, a. s., Brno, CZ) was used for microscopy. The samples were etched in a solution of HNO3 in ethyl alcohol—2% Nital and in etchant Cor (120 mL CH3COOH, 20 mL HCl, 3 g picric acid, 144 mL CH3OH).

The parametric test method of statistical hypotheses was chosen to verify the established hypothesis of the weight loss of materials 37MnSi5, S355JG3, HARDOX 450 and OK 84.58 and UTP 690 hardfacing materials. STATISTICA 12 software (Version number 1.0-0, StatSoft, Inc., Tulsa, OK, USA) was used to test statistical hypotheses.

The significance level of the test is chosen to be *α* = 0.05. It is necessary to test the equality of the variances before testing the difference between the two means. Additionally, therefore [34,35]:

$$H\_0: \sigma\_1^2 = \sigma\_2^2 \tag{3}$$

against

$$H\_1: \sigma\_1^2 \neq \sigma\_2^2\tag{4}$$

where *σ*2 1—variance of material weight loss values of standards S355J2G3, 37MnSi5; *σ*2 2—variance of material weight loss values of reference samples HARDOX 450 material, OK 84.58 and UTP 690 hardfacing materials.

A test of the two means difference was then performed. The software calculates the appropriate p-level. In order to verify the hypothesis on the basis of the graph, that the average value of the weight losses of the standard material is greater or smaller than the material of the reference sample. In this case, the software-calculated p-level must be divided by 2, as the software works with two-way hypothesis testing.

If the value of the p-level is greater than α, then *H*0 is not rejected, and thus the equality of the variances is confirmed. Conversely, if the *p*-level value is less than α, then *H*0 is rejected in favor of *H*1.

#### **3. Results and Discussion**

#### *3.1. Preliminary Research*

Individual materials were analyzed in terms of microstructure during the initial phase of the research. Figure 9a shows the microstructure of the standard material of 37MnSi5. The samples were etched in a solution of HNO3 in ethyl alcohol—2% Nital. The microstructure of the material was predominantly sorbite, referring to the fact that the raking blade was heat treated-hardened and then tempered at a high temperature.

**Figure 9.** Microstructure of the materials; (**a**) 37MnSi5; (**b**) S355J2G3; (**c**) HARDOX 450; (**d**) hardfacing material OK 84.58; (**e**) hardfacing material UTP 690.

Figure 9b shows the microstructure of the S35J2G3 material. A ferritic-pearlitic structure was observed, with a predominance of ferrite, corresponding to the type of microstructure of structural low carbon steels. We used 2% Nital as an etchant. This part of the ploughshare is not directly exposed to abrasion in contact with the road. It is a supporting part for the raking blade connected to the base material by a weld. However, with a larger amount of material to be cleaned, this part also comes into contact with the abrasive particles but with a lower degree of attack on its surface and is thus exposed to an abrasive load. The ferritic-pearlitic structure is characterized by a low degree of abrasive resistance. This was the reason for the idea of replacing such a weldment with one unit made of abrasion-resistant material.

Figure 9c shows the microstructure of HARDOX 450 material. The sample was etched with Cor etchant (120 mL CH3COOH, 20 mL HCl, 3 g picric acid, 144 mL CH3OH). The finegrained structure corresponds to the state after heat treatment-hardening and tempering, which is stated and declared by the manufacturer in his technical sheet [27].

Figure 9d shows the microstructure of OK 84.58 hardfacing coating. The samples were also etched with Cor etchant. The microstructure corresponds to the chemical composition with a high Cr and medium C content. These elements create a precondition for the formation of carbides and intermediate phases, hardening the softer ferritic matrix. This increases the hardness and also partly the abrasion resistance while maintaining the good toughness of the material.

Figure 9e shows the microstructure of the UTP 690 hardfacing coating. Samples were also etched with Cor etchant. The microstructure of UTP 690 material is very similar to the microstructure of OK 84.58 material. The hardfacing material UTP 690, with its chemical composition represented by Cr and W, increases wear resistance and hardness. The elements V and W refine the grain, which also promotes the abrasion resistance of the material where V increases the toughness needed to balance the increased hardness with carbides C, Cr and W. Compared to OK 84.58 hardfacing material, we can observe a needle-like structure in the UTP 690 hardfacing material, which could better transfer the loads that act on it and is thus a premise for better resistance to abrasive wear.

Microstructural analyses confirmed that the choice of hardfacing materials, which due to their chemical composition, create different and more suitable structures than the analyzed structures of the original ploughshare materials, was correct. This creates the premise of better abrasion resistance and impact resistance on the ploughshare.

The hardness was measured after verifying the microstructure of the materials. Hardness is the ability of a metallic material to resist the ingress of a foreign body. Therefore, the hardness of the material is an important value providing information on the resistance of the material to abrasive wear. At the same time, hardness values are needed to calculate *KT* hardness coefficients. The hardness of steel 37MnSi5, S355J2G3, HARDOX 450 and OK 84.58 and UTP 690 hardfacing materials was measured according to Vickers and Rockwell. Vickers hardness was measured according to the procedure stated in ISO 6507-1: 2018 [36] with a Vickers 432SVD hardness tester. The duration of the load was *t* = 15 s, and the loading force was *F* = 98.07 N. The Rockwell hardness was measured according to the procedure stated in ISO 6508-1: 2016 [37], with a UH250 hardness tester, and the loading force was *F* = 1471 N. Vickers hardness was used because it is more sensitive to small differences in material hardness. Rockwell hardness was used to better compare harder hardfacing materials. The average values of measured hardnesses obtained from ten measurements are shown in Table 5.

The measured hardness of 37MNsi5 steel (raking blade) was 538 HV0.5 and 50 HRC. The hardness of S355J2G3 steel (raking blade body) was 168 HV0.5 and 18 HRC. During its work, the ploughshare is stressed by abrasive wear not only on the raking blade but also on its supporting part. The idea of modifying the ploughshare within the meaning of changing the weldment into a solid piece of HARDOX 450 steel was based not only on removing the connecting part acting as a notch under stress, but also increasing the hardness of the new material compared to S355J2G3 material. The hardness of the HARDOX 450 material is higher compared to the S355J2G3 material, its value according to Vickers is 519HV0.5 and Rockwell is 45HRC. The aim of hardfacing additional materials to the raking blade was to increase the lifetime of the raking blade (37MnSi5) of the ploughshare. The OK 84.58 hardfacing material was the same hardness as the 37MnSi5 material, and its value was 546HV0.5 and 50 HRC. Significantly higher hardness compared to the 37MnSi5 material was achieved only by hardfacing material UTP 690, with which the hardness value was 677HV0.5 and 62 HRC. The results of the material hardness measurements predicted that the UTP 690 hardfacing material could be a suitable solution for ploughshare modification.

#### *3.2. Abrasive Wear Resistance Analysis*

The abrasion resistance test was firstly performed on standard samples of 37MnSi5 and S355J2G3 materials. Subsequently, the test was also performed on reference samples made of HARDOX 450 steel and with OK 84.58 and UTP 690 hardfacing materials. In Figure 10, samples after an abrasive wear test with traces of a rubber disc are presented.

For each material, three samples were used for the abrasion test. After each cycle, the sample was weighted three times on Kern ABS analytical scales, while the average values of the weight losses that were used for the next processing are shown in Table 6.

**Table 6.** Average weight losses of 37MnSi5, S355J2G3, HARDOX 450 steels and OK 84.58 and UTP 690 hardfacing materials.

Equation (1) [16] was used to calculate the hardness coefficients *KTE* and *KTV* of the standard materials 37MnSi5 and S355J2G3 and reference samples HARDOX 450, OK 84.58 and UTP 690 materials. The resulting values are shown in Table 7.

**Table 7.** Hardness coefficient values *KT*.

**Figure 10.** Samples after abrasive wear test.

If this coefficient is higher than 1, it is assumed that the material and the hardfacing material can withstand abrasive particles. It is clear from the graph that the largest value of the *KT* hardness coefficient was reached by the UTP 690 hardfacing material, namely 1.15. Other steels (37MnSi5, S355J2G3, HARDOX 450) and hardfacing material (OK 84.58) reached a value of *KT* inferior to 1. The S355J2G3 material of the ploughshare body reached the lowest value of *KTE*2 = 0.33 in comparison with all examined materials and the standard. Based on this result, it would also be appropriate to consider changing the base material to a HARDOX one.

The relative abrasion resistance Ψ*h* was then calculated according to Equation (2) from the weight losses of *Wh*. The relative resistance to abrasive wear was also calculated for the S355J2G3 basic material of the ploughshare, as it is also exposed to abrasive wear during raking [8]. The resulting values are shown in Table 8.

**Table 8.** Relative abrasion resistance Ψ*h*.

Materials 37MnSi5 and S355J2G3 have the value Ψ*h* = 1 because they are standard materials. The relative resistance to abrasive wear is the ratio of the weight loss of the standard material to the weight loss of the material, respectively, of the reference sample. If this coefficient is higher than 1, it is assumed that the material and the hardfacing material of the reference sample can withstand abrasive wear better than the material of the standard sample. Based on the test of resistance to abrasive wear, we can state that the sample from HARDOX 450 material achieved almost twice as good results as the standard sample from S355J2G3 steel.

As the abrasion resistance increases in direct proportion to the hardness of the material [5,9] by using higher grade HARDOX abrasion resistant steel with higher hardness, we can achieve even better abrasion resistance. With OK 84.58 hardfacing material, we achieved almost the same resistance to abrasive wear as the standard sample made of 37MnSi5 material. The highest value of Ψ*h* was reached by the UTP 690 hardfacing material, up to 4.5 times higher than the 37MnSi5 standard material. Based on these results, we can state that UTP 690 hardfacing material could be the most suitable for modifying the ploughshare.

Figure 11 shows the box plots with 95% confidence intervals. In the first case (Figure 11a), the weight loss values of S355J2G3 and HARDOX 450 materials were compared. It can be stated from the graph that the average values of weight loss of S355J2G3 and HARDOX 450 materials are not the same. Based on these results, it can be assumed that HARDOX 450 material will have better resistance to abrasive wear.

In the second case (Figure 11b), the values of the weight loss of 37MnSi5 material and OK 84.58 hardfacing material were compared. Based on the graph, it can be stated that the average values of the weight loss of 37MnSi5 material and OK 84.58 hardfacing material are almost the same, and thus hardfacing with such a hardfacing material on the exposed parts of the ploughshare will not significantly increase the lifetime.

In the third case, the values of mass losses of the 37MnSi5 material and UTP 690 hardfacing material were compared (Figure 11c). A comparison of the graphs clearly shows that the average values of weight loss of 37MnSi5 material and UTP 690 hardfacing material that UTP 690 hardfacing material will have better resistance to abrasive wear.

**Figure 11.** Box charts: (**a**) weight loss of S355J2G3 and HARDOX 450 materials; (**b**) weight loss of 37MnSi5 material and OK 84.58 hardfacing material; and (**c**) weight loss of 37MnSi5 material and UTP 690 hardfacing material.

#### *3.3. Discussion*

(a) Change of the S355J2G3 material of the supporting part of the ploughshare for the HARDOX 450 material

Based on the results, we can state that HARDOX 450 material has significantly better results compared to the S355J2G3 material of the basic ploughshare body. The hardness of HARDOX 450 material was 45 HRC, and the hardness coefficient of *KTV*1 reached the value of 0.83. The hardness of the basic body S355J2G3 material was 18 HRC, and the hardness coefficient of *KTE*2 reached the value of 0.33. These two basic data provide us with the initial information that HARDOX 450 material will better resist the abrasive particles present during the work cycle than the S355J2G3 material of the basic ploughshare body. The relative abrasion resistance Ψ*h*1 reached the value of 1.91. Based on this datum, we can say that HARDOX 450 material achieved almost twice as good results as the standard sample No. 2 made of S355J2G3 steel. In this case, it would be appropriate to verify the suitability of the higher class HARDOX material, e.g., HARDOX 550, which has higher hardness.

(b) Hardfacing on the exposed part of the raking blade with the OK 84.58 hardfacing material

Based on the results, we can state that the OK 84.58 hardfacing material achieved almost the same results in comparison with the 37MnSi5 material of the raking blade. The hardness of the raking blade 37MnSi5 material was 50 HRC, and the hardness coefficient of *KTE*1 reached the value of 0.93. The hardness of the OK 84.58 hardfacing material was 50 HRC, and the hardness coefficient of *KTV*2 reached the value of 0.93. These two basic data provide us with the initial information that the OK 84.58 hardfacing material will be worse as well as resist the abrasive particles present during the work cycle as a 37MnSi5 material. The relative resistance to abrasive wear Ψ*h*2 reached the value of 0.97. Based on this datum, we can say that the OK 84.58 hardfacing material achieved worse results by only 3% compared to the 37MnSi5 standard material of the raking blade. These elements create a precondition for the formation of carbides and intermedial phases hardening the softer ferritic matrix. This increases the hardness as well as partly the abrasion resistance while maintaining the good toughness of the material.

(c) Hardfacing on the exposed part of the raking blade with the UTP 690 hardfacing material

Based on the results, it can be stated that UTP 690 hardfacing material achieved better results compared to the 37MnSi5 material of the raking blade. The hardness of the UTP 690 hardfacing material was 62 HRC, and the hardness coefficient *KTV*3 reached the value of 1.15. These two basic data provide us with initial information that the UTP 690 hardfacing material will better withstand the abrasive particles present during the working cycle. The relative resistance to abrasive wear Ψ*h*3 reached the value of 4.57. Based on this data, we can say that the UTP 690 hardfacing material achieved more than 4.5 times better results compared to the 37MnSi5 standard material of the raking blade. In this case, we can state that the UTP 690 hardfacing material could significantly affect the lifetime of the ploughshare. The hardfacing material of the UTP 690 coating with its chemical composition represented by Cr and W increases wear resistance and hardness. The elements V and W soften the grain promoting the abrasion resistance of the material, where V increases the toughness needed to balance the increased hardness with carbides C, Cr and W. Compared to the OK 84.58 hardfacing material to transfer the loads that act on it and is, therefore, an assumption for better resistance to abrasive wear.

Based on the results, we can state that the hardness of the material strongly correlates with the resistance to abrasive wear. The hardness of HARDOX 450 was almost 2.5 times higher than S355J2G3. The relative abrasion resistance was almost twice as high for HARDOX 450 as for S355J2G3. The hardness and relative abrasion resistance of the 37MnSi5 material and the OK 84.58 hardfacing material were almost the same. Compared to the 37MnSi5 material, the UTP 690 material achieved higher hardness and higher resistance to abrasive wear.

#### **4. Conclusions**

Ploughshares are exposed to high wear, especially of the abrasive type, and their replacement is relatively economical. For this reason, it is necessary to look for ways to increase their lifetime and examine their resistance to abrasive wear.

When working with a ploughshare, it is not only the raking blade that wears rapidly but also its supporting part which the raking blade welded to. The article analyzes three ways to modify ploughshares. Based on the results, it is possible to state the following:

Based on the results, the manufacturer of ploughshares was recommended to use HARDOX 450 material as a basic material and UTP 690 coating material hardfacing on exposed parts of functional surfaces as a suitable means of increasing the lifetime of ploughshares.

In further research, it would be appropriate to also perform a test of resistance to abrasive wear for abrasion-resistant HARDOX sheet but of a higher class, i.e., with higher hardness, e.g., HARDOX 550 material, as well as for OK 84.58 hardfacing material which would be hardfaced in several layers. Then, the most suitable adjustments would be selected and tested under real operating conditions.

**Author Contributions:** Conceptualization, M.V., M.T. and K.M.; methodology, M.V. and M.T.; software, M.V., M.T. and K.M.; validation, M.V., M.T., K.M. and M.D.; formal analysis, M.V., investigation, M.V. and M.D.; resources, M.T. and M.V.; data curation, M.T., K.M. and M.D.; writing—original draft preparation, M.V., M.T. and K.M.; writing—review and editing, M.V. and K.M.; visualization, M.V. and K.M.; supervision, M.T.; project administration, M.T. and K.M.; funding acquisition, K.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the Ministry of Education, Science, Research, and Sport of the Slovak Republic through project APVV-19-0550.

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

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The article was supported by the APVV-16-0194 "Research on Impact of Innovation in Production Processes on the Life of Tooling and Components of Forest Mechanisms".

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

#### **References**


**1. Introduction**

#### **1.1. Response of aquatic organisms to exposure to toxic substances**

Exposure to toxic compounds has not only lethal but also important sublethal effects upon affected individuals. Successful identification of molecular mechanisms underlying response to toxic exposure depends upon development and use of a suitable set of assays, and several approaches are potentially available. While various biomarkers [1, 2] or gene expression [3, 4] assays have been demonstrated for marine mollusks in recent years, there has been no parallel work for freshwater mussels, many of which are of conservation concern. More fundamentally, adaptation of existing assays to freshwater mussels is not entirely attractive because a focus on candidate genes of known function certainly will miss genes or biochemical pathways that are not known. A preferable approach would be to screen global gene expression and thereby identify genes of interest not only in known but also in unknown pathways. Three approaches are available. Microarrays are available for several marine mollusks, and have in some cases been used for purposes of characterizing responses to environmental stressors including toxins or other bioactive compounds (e.g., marine mussels [5–8], Manila clam *Venerupis philippinarum* [9]). There are no existing microarrays for freshwater mussels, however, and construction of such screening platforms would require a large body of work developing and characterizing expressed sequence tags for hundreds to thousands of genes. Subtractive hybridization has been applied to other mollusks, such as the invasive zebra mussel *Dreissena polymorpha* [10], Pacific oyster *Crassostrea gigas* [11], and peppery furrow shell *Scrobicularia plana* [12], and has been shown a viable but technically challenging approach to identifying differentially expressed genes. Next-generation DNA-sequencing technology has made it possible to cost-effectively screen expression of all genes transcribed in tissues of interest, even in species for which prior knowledge of the genome is lacking. The approach is tantamount to sequencing all the RNAs produced in that tissue; hence, the approach is referred to as RNAseq. In our context, RNAseq makes quantitative comparison of gene expression in selected tissues among toxin-challenged and control individuals possible. Against this background, the goal of this study was to relate gene expression end points in a representative freshwater mussel, pheasantshell *A. pectorosa*, to exposure to arsenate and sulfate, two pollutants resulting from coal combustion and mining, respectively.

#### **1.2. Freshwater mussels**

Freshwater mussels (Class Bivalvia: Family Unionidae) have their center of biodiversity in the southeastern United States. However, many regionally important species face a variety of threats, including exposure to toxic compounds. In particular, mussels of the Clinch and Powell River systems of southwest Virginia have been heavily impacted by runoff, leachates, or spills of materials related to coal extraction, processing, and use for electric power generation. Given the continued operation of coal extraction and processing facilities, the shift from deepto surface-mining practices, and the increase in coal-bed gas extraction wells in the Clinch and Powell River system, defensible biological assays for assessing the impacts on key components of this aquatic ecosystem must be developed. These assays could provide critical information for assessing the impacts of future toxic events and thereby allow characterization of potential long-term effects of resource extraction on freshwater mussel populations. This project was conducted to show the response of freshwater mussels to selected physiological stressors. Within this context, the objective of the study was to screen gene-transcriptional markers in a laboratory study under controlled conditions, focusing upon arsenate and sulfate, two contaminants related to coal mining and processing. Identification of such genetic markers could prove essential for use in future nonlethal determinations of contaminant impacts to federally listed mussels.

#### **1.3. Contaminant selection**

**1. Introduction**

100 Organismal and Molecular Malacology

**1.2. Freshwater mussels**

**1.1. Response of aquatic organisms to exposure to toxic substances**

Exposure to toxic compounds has not only lethal but also important sublethal effects upon affected individuals. Successful identification of molecular mechanisms underlying response to toxic exposure depends upon development and use of a suitable set of assays, and several approaches are potentially available. While various biomarkers [1, 2] or gene expression [3, 4] assays have been demonstrated for marine mollusks in recent years, there has been no parallel work for freshwater mussels, many of which are of conservation concern. More fundamentally, adaptation of existing assays to freshwater mussels is not entirely attractive because a focus on candidate genes of known function certainly will miss genes or biochemical pathways that are not known. A preferable approach would be to screen global gene expression and thereby identify genes of interest not only in known but also in unknown pathways. Three approaches are available. Microarrays are available for several marine mollusks, and have in some cases been used for purposes of characterizing responses to environmental stressors including toxins or other bioactive compounds (e.g., marine mussels [5–8], Manila clam *Venerupis philippinarum* [9]). There are no existing microarrays for freshwater mussels, however, and construction of such screening platforms would require a large body of work developing and characterizing expressed sequence tags for hundreds to thousands of genes. Subtractive hybridization has been applied to other mollusks, such as the invasive zebra mussel *Dreissena polymorpha* [10], Pacific oyster *Crassostrea gigas* [11], and peppery furrow shell *Scrobicularia plana* [12], and has been shown a viable but technically challenging approach to identifying differentially expressed genes. Next-generation DNA-sequencing technology has made it possible to cost-effectively screen expression of all genes transcribed in tissues of interest, even in species for which prior knowledge of the genome is lacking. The approach is tantamount to sequencing all the RNAs produced in that tissue; hence, the approach is referred to as RNAseq. In our context, RNAseq makes quantitative comparison of gene expression in selected tissues among toxin-challenged and control individuals possible. Against this background, the goal of this study was to relate gene expression end points in a representative freshwater mussel, pheasantshell *A. pectorosa*, to exposure to arsenate and

sulfate, two pollutants resulting from coal combustion and mining, respectively.

Freshwater mussels (Class Bivalvia: Family Unionidae) have their center of biodiversity in the southeastern United States. However, many regionally important species face a variety of threats, including exposure to toxic compounds. In particular, mussels of the Clinch and Powell River systems of southwest Virginia have been heavily impacted by runoff, leachates, or spills of materials related to coal extraction, processing, and use for electric power generation. Given the continued operation of coal extraction and processing facilities, the shift from deepto surface-mining practices, and the increase in coal-bed gas extraction wells in the Clinch and Powell River system, defensible biological assays for assessing the impacts on key components of this aquatic ecosystem must be developed. These assays could provide critical information The coal industry is a potential source of numerous contaminants to aquatic environments. In several Virginia watersheds, habitat for imperiled freshwater mussel populations exists in close proximity to coal industry-associated activities. These activities include mining and coal-fired electric power plants with on-site storage of coal combustion residue (CCR). Two contaminants were selected for this study based on their association with surface mining (sulfate, SO4 2-) or CCR storage (arsenate, As(V)). The contaminants As and SO4 2- were selected due to their environmental relevance and the potential for concentrations to become elevated due to activities related to coal mining and power generation.

Freshwater bivalves appear to be relatively tolerant to acute effects of As; the estimated 96-h LC50 for Asian clam *Corbicula fluminea* is 20,740 µg/L As, with no mortality observed at concentrations up to 5000 µg/L for 21 days [13]. In surface waters, the majority of total As will be As(V) under oxygenated conditions. However, investigations of sublethal effects of As on bivalves have generally focused on As(III). Exposures of bivalves to As(III) have demonstrated histological effects including increased damage to digestive gland tissue [14] and biochemical effects including alteration of levels of adenosine triphosphate [15], inhibition of the detoxification enzyme catalase [14], and changes in the activity of glutathione-S-transferase (stimulation and inhibition) [14, 16]. Detoxification of As(III) and As(V) involves reduced glutathione and glutathione-dependent enzymes, and effects on this system in bivalves have been shown to be variable and dependent on both concentration and chemical speciation [14, 16]. The sublethal effects of environmentally relevant concentrations of As(V) on freshwater mussels are currently unknown.

Freshwater bivalves also appear to be relatively tolerant to acute effects of SO4 2-. Soucek and Kennedy [17] determined a sulfate 96-h LC50 for grooved fingernail clam *Sphaerium simile* of 2078 mg/L. However, exposure of *C. fluminea* to 1500 mg/L SO4 2- reduced feeding rates over a 4-week period [18].

For each contaminant, a relatively 'high' concentration was selected based on worst-case conditions previously measured in heavily impacted environments. The concentration of SO4 2- (1250 mg/L) was based on low-flow measurements up to 1200 mg/L in a notoriously polluted river in West Virginia, USA [19]. The high concentration of As (1000 µg/L) was based on measurements in pore-water downstream of a massive CCR spill (up to 1200 µg/L; [20]). For both chemicals, the selected concentrations were not expected to cause mortality based on results of acute and chronic toxicity studies conducted with other bivalves (*S. simile* and *C. fluminea;* [13, 17, 18, 21]). The majority of toxicity tests with As have been conducted with arsenite (As(III)), the more toxic form of As. However, due to the oxygenated environment in our exposure system, mussels were exposed to As as arsenate (As(V)). Hence, the purpose of this study was to determine whether As (as As(V)) and SO4 2- caused sublethal changes in freshwater mussels, the nature of these changes, and the relationships between biochemical, histological, and genetic markers.


*2.4.2 Design for reliability and maintenance*

Design for reliability is crucial aspect in the aerospace industry, where reliability is a must considering the mission criticality of these systems [8]. Reliability somewhat depends on the assembly process employed. One indication is to avoid those manufacturing processes that are less repeatable or controllable.

Design for maintenance shared some requirements with design for test, since any maintenance activity starts with identifying the part in failure within the system. Other aspects consist in the designing the parts in a modular way so any failed item can be easily replaced without having replace the entire system or sub-system,


e. **Impact on scene and Odor contamination:**

Huge heaps of decline and trash being open unloaded and littered over a space ruins the serenity of the scene. The emanation of harmful and foul gases from landfills dirties the climate and causes genuine consequences for wellbeing of certain individuals. The horrendous smell makes burden others.


*4.3.1. Air temperature*

The temperature thermostats were possibly set too high in SP1. It is possible that the Ta re‐ corded for SP1 House A would have been considerably higher if the occupants had not opened the windows in the bedrooms so frequently. The need to naturally ventilate to dif‐ ferent degrees between House A and House B, but with similar temperature outcomes, sup‐ ports the observation of a difference in IAQ between the two houses. Likewise, it can be assumed that the thermostats in SP2 were set too low, resulting in one of the occupants al‐ tering the settings in House B to compensate. This evidence further identifies a difference between House A and House B. Whether the difference in Ta is due to construction type, a variation in MVHR system or a study limitation, the unacceptable Ta experience highlights the need for a greater degree of occupant control in order to achieve the ideal sleeping tem‐ perature.


**What Are the Roles of National and International Institutions to Overcome Barriers in Diffusing Clean Energy Technologies in Asia?: Matching Barriers in Technology Diffusion with the Roles of Institutions**

Masachika Suzuki

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/54124


**Abstract**

Implant supported restorations have become an ideal treatment alternative for the rehabilitation of edentulous sites. However alveolar bone defects due to resorption, trauma or oncologic diseases may considerably affect favorable implant positioning and prosthetic outcomes. Various alveolar ridge augmentation procedures are available to gain enough bone volume and apply the ideal treatment plan afterwards. Guided bone regeneration, ridge splitting, distraction osteogenesis, maxillary sinus augmentation and autogenous block bone grafting are main techniques which have successful outcomes in reconstruction of bone defects. It's difficult to demonstrate that one augmentation procedure offers better outcomes than another. Studies documenting augmentation techniques seem to be comparable and state favorable results for each procedure.

**Keywords:** biomaterials, alveolar ridge deficiency, distraction osteogenesis, ridge splitting, guided bone regeneration, onlay block bone graft


**6. Conclusion**

A well-known fact is that plant growth, development and senescence are under the regulation of the system of natural growth regulators: natural inhibitors and phytohormones. These substances could be transported in the cell or even between the plant tissues and organs. Phytohormones are involved in wide range of functions, ranging from growth and development to biotic and abiotic stress tolerance. Efficiency of plant hormone is increased by their ability to crosstalk under different conditions. We can use research in plant hormones to improve crop growth and production, as they regulate complex signalling networks involving developmental processes and environmental stresses. Significant progress has been made in identifying the key components and understanding plant hormone signalling (especially salicylic acid, Jasmonic acid and Ethylene) Several recent studies provide evidence for the involvement of other hormones such as Abscisic acid, Auxin, Gibberellins, Cytokinins and Brassinosteroids in plant defence signalling pathways. To understand how plants coordinate multiple hormonal components in response to various developmental and environmental cues is a major challenge in research. It is important to note that the type of interactions and plant responses to stresses vary depending on the plant system as well as the time, quantity and the tissue where hormones are produced.

*Plant Abiotic Stress Responses and Tolerance Mechanisms*


**6.3. Market size, innovation, and changing demand elasticity**

In one of the first studies investigating the relationship between market size and innovation, Griliches [31] put forward in 1957 the existence of a significant relationship between technological change and technological adaptation and profitability and market size. In other studies analyzing different sectors following this study, a significant relationship between market size and innovation and innovation elasticity was exhibited [32–34]. In this context, the innovation process, which improves as market size grows, increases price elasticity of demand by supporting the increase of product range [35].

In the light of these analyses, macroeconomic variables, such as short and long term structures, commerce liberalization and competition, market size, and innovation, affect and change the price elasticity of demand for luxury and necessity goods. This change generally reveals itself as the increase of price elasticity of demand for goods. This macrochange of demand elasticity in both luxury and necessity goods composes a risk for firms in microterms. On the other hand against this risk, firms try to decrease the demand elasticity for their products by creating brands and increasing loyalty to these brands [8].

Brand loyalty decreases the sensitivity of consumers to the prices of products especially in product groups such as technological products and automobiles. At this point, it is useful to mention about brand loyalty as a microvariable effective on price elasticity of demand.


**2. Hypoxia and lung cancer, HIF-1α, carbonic anhydrase IX and glucose transporter glut**

Hypoxia is one of the most important challenges for tumor growth and survival. The angio‐ genesis is a fundamental to avoid tumor necrosis (TN); every cell in a tissue is forced to be within 100μm capillary blood vessel [5].

Hypoxia inducible factor-1 (HIF-1) is a regulator of VEGF under hypoxia conditions [21].

HIF-1 is a heterodimer consisting of 2 subunits, HIF-1α and HIF-1β (otherwise known as the aryl hydrocarbon receptor nuclear translocator), which is stabilized by hypoxia. The expres‐ sion of these subunits is different; HIF-1β is constitutively expressed, unlike HIF-1α, which is rapidly degraded under normoxic conditions [22]. In the presence of oxygen, HIF-1α is hydroxylated on conserved prolyl residues within the oxygen-dependent degradation do‐ main by prolylhydroxylases and binds to von Hippel-Lindau protein (pVHL), which in turn targets it for degradation through the ubiquitin-proteasome pathway [23-26]. Hypoxia in‐ hibits hydroxylation of prolyl residues 402 and 564 in the oxygen-dependent degradation domain that avoid binding of the pVHL. Similar hypoxia-dependent inhibition of hydroxy‐ lation of asparagines residues within the C-terminal activation domain increases HIF-1α transcriptional activity. Oxygen-dependent degradation of HIF-1α is inhibited by *src* and *ras* oncogenes [22-25].

The HIF-1 complex recognizes hypoxia response elements on the promoter of several genes, including VEGF, PDGF, and TGF-α [26].

Growth factors, cytokines and oncogenes, which stimulate p42/p44 mitogen-associated pro‐ tein kinase (MAPK) and/or phosphoinositidyl-3 kinase (PI-3K) pathways, may enhance HIF-1 activity. HIF-1 binds to a conserved sequence (5-CGTG-3) known as the hypoxic re‐ sponse element in the promoter region of its target genes. These target genes are involved in processes that promote cellular survival, angiogenesis, blood vessel vasodilatation, erythro‐ poiesis, anaerobic metabolism, buffering of the intracellular compartment and induction of growth factors. HIF-1 activity *in vivo* promotes tumor growth in the most of the studies and resistance to several chemotherapy agents, as platinum compounds [22]. Carbonic anhy‐ drase (CA) IX and glucose transporter-1 are other transcriptional targets of HIF-1 and, along with HIF-1, have been identified as novel markers of hypoxia in different tumor types [27-31]. Up-regulation of CA IX in vivo in a perinecrotic pattern suggests this may be an im‐ portant pathway in hypoxia, possibly regulating pH to allow survival of cells under hypoxic conditions [28].

[7,10-18]. VEGF is continuously expressed throughout the development of many tumor types, and is the only angiogenic factor known to be present throughout the entire tu‐ mor life cycle [19]. The clinical significance of circulating levels of VEGF in patients with

Since tumor growth and metastasis are angiogenesis-dependent, relying upon the genera‐ tion of new blood vessels to sustain proliferation, survival and spread of the malignant cells, therapeutic strategies aimed at inhibiting angiogenesis area theoretically attractive. Target‐ ing and damaging blood vessels can potentially kill thousands of tumor cells. The antiangio‐ genesis and vascular targeting strategies, therefore, may no result in whole tumor cell kill, but may maintain stable disease: this has given rise to the concept *cytostatic paradigm* [20].

The investigation and development of different anti-angiogenesis and vascular targeting

**2. Hypoxia and lung cancer, HIF-1α, carbonic anhydrase IX and glucose**

Hypoxia is one of the most important challenges for tumor growth and survival. The angio‐ genesis is a fundamental to avoid tumor necrosis (TN); every cell in a tissue is forced to be

Hypoxia inducible factor-1 (HIF-1) is a regulator of VEGF under hypoxia conditions [21].

HIF-1 is a heterodimer consisting of 2 subunits, HIF-1α and HIF-1β (otherwise known as the aryl hydrocarbon receptor nuclear translocator), which is stabilized by hypoxia. The expres‐ sion of these subunits is different; HIF-1β is constitutively expressed, unlike HIF-1α, which is rapidly degraded under normoxic conditions [22]. In the presence of oxygen, HIF-1α is hydroxylated on conserved prolyl residues within the oxygen-dependent degradation do‐ main by prolylhydroxylases and binds to von Hippel-Lindau protein (pVHL), which in turn targets it for degradation through the ubiquitin-proteasome pathway [23-26]. Hypoxia in‐ hibits hydroxylation of prolyl residues 402 and 564 in the oxygen-dependent degradation domain that avoid binding of the pVHL. Similar hypoxia-dependent inhibition of hydroxy‐ lation of asparagines residues within the C-terminal activation domain increases HIF-1α transcriptional activity. Oxygen-dependent degradation of HIF-1α is inhibited by *src* and *ras*

The HIF-1 complex recognizes hypoxia response elements on the promoter of several genes,

Growth factors, cytokines and oncogenes, which stimulate p42/p44 mitogen-associated pro‐ tein kinase (MAPK) and/or phosphoinositidyl-3 kinase (PI-3K) pathways, may enhance HIF-1 activity. HIF-1 binds to a conserved sequence (5-CGTG-3) known as the hypoxic re‐ sponse element in the promoter region of its target genes. These target genes are involved in processes that promote cellular survival, angiogenesis, blood vessel vasodilatation, erythro‐

NSCLC is controversial.

**transporter glut**

oncogenes [22-25].

strategies are of interest with respect to lung cancer.

4 Oncogenesis, Inflammatory and Parasitic Tropical Diseases of the Lung

within 100μm capillary blood vessel [5].

including VEGF, PDGF, and TGF-α [26].

Other study showed that HIF-1 is commonly expressed in NSCLC and is involved in the pathogenesis of NSCLC. HIF-1 expression seems associated with a poor prognosis and this was found to be as an independent factor. A similar observation has been made for the prognostic impact of the extent of TN, another marker for hypoxia in NSCLC, where although extensive TN predicts outcome in earlier stages of the disease, no such effect is seen in locally advanced disease. Thus, a number of other studies have included patients with locally advanced disease in different cancer types and reported an association be‐ tween HIF-1 expression and prognosis [22]. Although some other studies have reported different results [32].

The associations between HIF-1, CA IX, TN and squamous NSCLC are coherent with the known pathways that regulate and are regulated by HIF-1. CA IX is regulated by HIF-1. TN and CA IX have been associated with a poor prognosis in NSCLC [22,31].

By other hand, glucose transporter GLUT-1 is a potential intrinsic marker of hypoxia in can‐ cer [29]. VEGF and GLUT-1 are similarly regulated in response to hypoxia [33]. They may functionally help each other to endure hypoxia. Therefore, an upregulated expression of GLUT-1 allows the cell to better use an inadequate source of glucose, while an upregulated expression of VEGF will improve the reserve of glucose and oxygen through the recruitment of additional blood vessels [33].


1. Introduction

Within the modern aircraft industry, More Electric Aircraft technology is growing rapidly. Figure 1 shows a general block diagram for MEA power distributions. The power distribution system model consists of power generation unit, transformer rectifier unit, DC-DC converter unit, and DC-AC inverter unit.

The satisfactory performance of MEA depends to a very great degree on the continuing reliability of electrical systems and subsystems. This technology has many benefits and advantages such as:

© 2018 The Author(s). Licensee InTech. 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, provided the original work is properly cited.

© The Author(s). Licensee InTech. 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 eproduction in any medium, provided the original work is properly cited.

Figure 1. MEA general power distribution system.

In MEA Power Electronics segment plays a very important part in controlling the energy and improving both generators and actuators energy conversion. Furthermore, in a fixed frequency system (400 Hz) a mechanical constant speed drive set between the engine and the aircraft generator, however this will give extra weight and must be frequently maintained.

The use of Power Electronics helps in reducing weight, is easier to maintain, and provides more controllability and intelligence which includes fault detection and diagnosis [1–6].

A conventional 12 pulse rectifier using Diode Bridge is one of the simplest converter since does not require any control loop, however, this type of converter has a fixed DC output with high Total Harmonic Distortion (THD) on the input current compared with the proposed 12-pulse active rectifier.

The system has the ability to stabilize an output voltage of variable Vdc from a 3 phase 360– 800 Hz, 115 V RMS system. Using a decoupling feed-forward control method by DQ frame technique, the magnitude and the phase of the input current can be controlled and hence the power transfer that occurs between the AC and DC sides can also be controlled. The converter could be suitable to use with an electric actuator (or other) aircraft loads. The system could be used as DC source for DC loads or to feed DC to AC inverter for a fixed 400 Hz supply. The design of this system poses significant challenges due to the nature of the load range and supply frequency variation and requires many features such as:

1. Sinusoidal and low harmonics contents on supply current.

Generally, use of electrical power on board is continuously increasing within the areas of communications, surveillance and general systems, such as: radar, cooling, landing gear or actuators systems. DC voltage of up to 540 V [9] may be required for electric power distribution to feed certain loads.


**Insecticide Use and the Ecology of Invasive** *Liriomyza* **Leafminer Management**

Stuart R. Reitz, Yulin Gao and Zhongren Lei

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/53874


**6.1 Pest and disease management in ginger (***Zingiber officinale***)**

Ginger cultivation is affected by both biotic and abiotic factors. Biotic factors are viruses, bacteria, fungi and nematodes [112, 113] with bacteria being the most important causing wilt and soft rot. The next major pathogen after bacteria is fungi which causes rhizome rot, soft rot, sclerotium rot and yellows disease. Nematode causes root-knot disease while viruses causes mosaic and chlorotic fleck in ginger plants leading to reduction in rhizome yield of the plants. In River State of Nigeria, a survey was conducted by [114] and it was reported that the most abundant arthropods in stored ginger was mites then *Lasioderma serricorne*. Reports have it that *Aspergilus flavus, Aspergilus niger, Fusarium oxysporium* and *Rhizopus* sp. were fungi pathogens isolated from dried ginger samples with high occurrences *of A. flavus*. According to a survey in Rivers State, Nigeria, stored ginger has no immunity against arthropod pest infestation and fungal infection. It was also observed that population dynamics of arthropod *Nigeria Root Vegetables: Production, Utilization, Breeding, Biotechnology and Constraints DOI: http://dx.doi.org/10.5772/intechopen.106861*

pests of stored ginger was affected by seasonal variation. The four main diseaseS and pestS of ginger as reported by THE National Agricultural Advisory services (NAADS) Uganda are rhizome rot, soft rot, root-knot nematode and rhizome scale.

#### *6.1.1 Rhizome rot*

It is a partly/completely decomposition of rhizome tissue; root may dry, wet, soft or slimy and color turns black. This rot is caused by the fungus (*Fusanum Oxysporum*) both in the field and post-harvest when ginger is washed in dirty (recycled) water, poor aeration and storage in contaminated sheds where rotten piles of reject ginger is allowed to accumulate.

#### *6.1.2 Soft rot*

Soft rot is caused by fungus *Pythium gracile*, either alone or in combination with a bacterium *Erwinia* species. The fungus *Pythium* is a water-mold and develops maximally in moist conditions when temperatures are favorable. Prolonged wet weather, therefore, creates ideal conditionS for development of soft-rot disease in ginger.

#### *6.1.3 Root knot nematode*

It is caused by the nematode (*Meloidogyne incognita*) which attacks both the root and ginger rhizome, resulting in warty overgrowth on them. The nematode normally burrows themselves into the soil and form knots on the roots and rhizome. In this way, they attack the plant by feeding on the food and nutrients which should be used by the plant for growth and production. Therefore, because of starvation with nutrients and food, the plant dies.

#### *6.1.4 Rhizome scale*

The size and shape of this scale insect is about 0.5–2 mm in diameter and usually circular in shape. They normally have a shell color brown on top which act as coverage and protection. It attacks the rhizome of the plant by sucking out the juice from it thus resulting in wilting and death of the plant. It is hard or difficult to treat this pest (using insecticides or even hot-water treatment) because of the shell forming on top which protects the insect from dying.

Apart from these major pest and diseases, others include Fungi and bacteria such as Thread blight *Ceratobasidium* sp.; *Corticium* sp., Stem rot (*Athelia rolfsii*), Leaf spot (*Magnaporthe Grisea*).

#### *6.1.5 Nematodes*

Burrowing Nematode—*Radopholus similis* (associated with rhizome rot); Reniform nematode- *Rotylenchulus reniformis* (yellowing leaf drying and stunting); Pin nematode *Criconemoides onoensis*

#### *6.1.6 Yellow leafspot of ginger*

Over the years, ginger yellow leaf spot disease has posed a serious challenge to increased ginger production in Nigeria [115]. The most susceptible stage which is

three- to four-leaf stage coupled with high humidity has been observed to be conducive for the disease spread. Ginger plants of up to 6–7 months old are also susceptible to this disease. Grasses have been reported as reservoir hosts while agents of dispersal are rainwater and wind [116]. This disease spread widely in ginger-growing areas with resistance to benomyl (Benlate 50wp), mancozeb (Diathane m-45), and Kocide 101 (copper hydroxide) treatments. In the rainforest agro-ecology of Nigeria, though there may be appearance of early signs of the disease but severity is usually noticeable towards the end of vegetative growth.