*2.3. Approaches*

The following comparisons and approaches were carried out in order to achieve the aforementioned goals.

Equivalent energy—Shape factor. All the dwellings, original building materials, original locations and original morphology: The resulting values for equivalent energy were compared with the corresponding shape factors in order to check if there is any relation between them. The dwellings were situated in their original locations, and their original building materials were assigned. This way, the features that do not influence on the shape factor, but do influence on the equivalent energy, affect the results and the difference between these two values can be observed. Besides, the factors that influence these conclusions were analyzed.

Equivalent energy—Morphology. All the dwellings, same building materials, same locations, without openings: In order to establish a relation between the results of equivalent energy and the morphology of the dwellings, the models were reduced to their volumes. This means that their openings were removed, the same material was assigned to all of them and they were situated in the same ten locations (where the pueblos of New Mexico were built, that is to say, the locations the most sedentary dwelling was built). This way, all the dwellings contain the same information as the shape factor takes into account; that is to say, the surface of their envelope and the volume that is contained under it. The only characteristic which could not be eliminated was the orientation of the dwellings, not present in the shape factor and impossible to be removed from the DesignBuilder calculations. The building materials that were used in this approach are the ones that correspond to the template entitled "Timber frame-superinsulated", which appears on the database of DesignBuilder v<IP_ADDRESS> and whose details are featured in Appendix A (Table A3).

Equivalent energy—Location. All the dwellings, both original and same locations, original building materials and original morphology: Two groups of calculations were developed for this approach in order to determine how location influence the equivalent energy. First, the equivalent energy corresponding to the original placements, their original materials and their original openings, was calculated. Second, those dwellings were moved to the locations where the New Mexican pueblos were built, and the corresponding equivalent energy was calculated as well. Therefore, the only feature that changes from one case to the other one is the location. This way, by moving the dwellings from

their original locations to the ones of New Mexico, it can be determined if the values of equivalent energy for each dwelling are influenced by its location and its climatic conditions.

Equivalent energy—Building materials. Just one dwelling, original materials and same locations: By means of this approach, it was possible to determine the links between the original building materials and the equivalent energy. In order to achieve it, the morphological and environmental factors were eliminated. Thus, it is possible to establish the relation between the temperature, the humidity level, the technical characteristics of the building materials and the equivalent energy that correspond to each of them. This way, the consequences that each material has on the indoor ambient and on the equivalent energy can be determined.

Specifically, the calculations presented in this section imply to take one single dwelling and assigning it the main building materials of the other dwellings which were analyzed. Thereby, the chosen dwelling was the wigwam, and the composition of all the envelopes was assigned to it one by one: the cattail mats (its original material), the hogan envelope, the tipi hides, the multilayer envelope that covered the earthlodge, the bundles of grass typical of a grass house, the bark sheets that wrapped the longhouses, the adobe that composed the walls of the pueblos and, finally, the cedar planks that protected the interior of Haida houses. Eight versions of the same dwelling that were situated in the ten locations corresponding to the pueblos of New Mexico.

All the building materials described before were characterized by means of their diffusivity, their effusivity, their thermal transmittance and their thermal lag [78].


**Author details**

Paul Agbekpornu1 \* and Isaac Kevudo2

1 Department of Statistics and Actuarial Science, Kwame Nkrumah, University of Science and Technology (KNUST), Ghana

2 School of Medicine, University of Health and Allied Science (UHAS), Ghana

\*Address all correspondence to<EMAIL_ADDRESS>
© 2023 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, provided the original work is properly cited.

*The Risks of Microplastic Pollution in the Aquatic Ecosystem DOI: http://dx.doi.org/10.5772/intechopen.108717*


(1) Superoxide Dismutase and Peroxidases

As mentioned before, HO• is chemically very reactive, so the first line of defense of parasitic flatworms is to prevent its production, the controlled reduction of H2O2 to H2O being vital. The classic enzyme that carries out this reaction in aerobic organisms is catalase (CAT), which is absent in the genomes of parasitic flatworms [92,133] but is conserved in their free-living counterparts [134]. Hence, these parasites depend on enzymes glutathione peroxidase (GPx) and peroxiredoxin (Prx) in addition to the superoxide dismutase (SOD) necessary for O2 •− scavenging.

SOD is a family of metalloenzymes specialized in carrying out the dismutation of O2 •−, generating O2 and H2O2. In animals, it is possible to identify two isoforms: (a) cytoplasmic SOD dependent on one atom of copper and another of Zn (Cu/Zn SOD); (b) mitochondrial SOD, dependent on a manganese atom (Mn SOD). Experimentally, it has been possible to isolate the enzyme [71] or clone the gene [135] from some parasitic flatworms, such as *T. solium*; thus, it was not surprising to confirm that, in genomes/transcriptomes, both trematode [125] and cestode [92,136] genes are present in both isoforms. Regarding their expression, their presence has been determined in all stages of the life cycle associated mainly with the tegument of these organisms [31], although a greater expression has been observed in the adult forms with respect to the larval [137].

GPx comprises isoenzymes that carry out the reduction of H2O2 to H2O, requiring electrons from two molecules of the tripeptide glutathione (GSH), taking it to its oxidized disulfide form (GSSG). Although this family has many representatives in mammals [138], in trematodes [125] and cestodes it has only been possible to identify a single gene [92] corresponding to a selenium-dependent GPx. This GPx type turned out to be membrane integral and it is exclusive for the reduction of lipid hydroperoxides (Ph-GPx); thus, it makes sense that it has been located in the tegument [137] of the different stages of trematodes *S. mansoni* [125] and *Fasciola gigantica* [139], and of the cestode *E. granulosus* [140]. Like SOD, this enzyme has a differential expression that is a function of the pO2 to which the parasite is exposed, finding its highest expression in the aerobic life cycle stages and its lowest in the anaerobic [141]. However, the overexpression of this enzyme responds to the exposure of exogenous oxidants, as shown in *C. sinensis* under in vitro conditions [142]. Cai et al., suggesting that Ph-GPx activity could be more focused on egg production than on the maintenance of the redox status [142].

Prxs are homodimeric proteins that catalyze the reduction of H2O2 and alkyl hydroperoxides to water and alcohol, respectively. The electrons that translocate frequently come from the 12 kDa protein thioredoxin (Trx), which is why these enzymes are also called thioredoxin peroxidases (TPx), although some isoforms can also obtain electrons from GSH. Despite the abundance of Prxs, their catalytic efficiency is lower than that of CAT or GPxs by one to three orders of magnitude [143]. However, this family of enzymes seems to be the most important in the H2O2 degradation process, both in trematodes and cestodes. In fact, in the genomes of *E. granulosus*, *E. multilocularis*, *H. microstoma*, and *T. solium*, it has been possible to identify three different genes encoding Prx 1–3 [92], which is consistent with the identification of three Prxs in *S. mansoni* [85]. Wang et al. reported that GPx activity in echinococcal cysts is practically undetectable, suggesting the relevance of Prxs in this parasite [144]. Using western blot analysis, it was found that in the trematode *O. viverrini*, OvTPx-1 is expressed in all stages of development; even if its location is different,

depending on the isoenzyme [127]. For example, in adult flukes of *Schistosoma japonicum* it has been possible to locate Prx-1 in the tegument whereas Prx-2 has been found associated with the parenchyma, vitelline glands, and gastric epithelium [145]. In *H. diminuta*, a peroxidase-like activity was described in 1968 [146].


**1. Introduction**

Posttraumatic stress disorder (PTSD) is an often debilitating mental disorder that may occur following trauma exposure [1]. PTSD is characterized by four diagnostic clusters—(1) the re-experiencing the traumatic event (e.g., recurrent memories, dreams, or flashbacks); (2) symptoms of avoidance (e.g., efforts to evade trauma reminders); (3) arousal (e.g., hypervigilance, sleep disruptions); and (4) negative

cognitions and mood (e.g., self-blame) [1]. Substance use disorder (SUD) is another psychiatric disorder characterized by 11 possible symptoms which involve negative consequences arising from one's substance use and inability to control one's substance use [1]. In the last version of the *Diagnostic and Statistical Manual of Mental Disorders* (the DSM-5; [1]), craving, the often intrusive desire to use the substance, was added as one of the 11 symptoms characterizing a SUD [1].

PTSD often co-occurs with SUD. Research has documented high rates of comorbidity between PTSD and alcohol use disorder (AUD) [2], cannabis use disorder (CUD) [3, 4], and other SUDs [5]. The prognosis of comorbid PTSD-SUD is worse than either disorder alone [6] with comorbid PTSD-SUD leading to greater functional impairment in comparison to those with only PTSD or a SUD [7].

It has been suggested that PTSD and SUD are likely functionally related to one another [8] in comorbid individuals. While the precise underlying mechanisms are not well understood, there are several learning theories that may help explain the high rates of substance misuse in people with trauma histories and help us understand the high comorbidity of PTSD with SUD. The first is the two-factor learning theory which was originally developed by Mowrer to explain the acquisition and maintenance of phobias [9] and which has more recently been applied by Stasiewicz [10] to the acquisition and maintenance of SUDs. Two-factor learning theory applies a combination of classical conditioning and operant conditioning mechanisms to the development and maintenance phases of these disorders, respectively. Applying this theory to the co-occurrence of PTSD and SUDs in traumatized individuals, trauma-relevant cues that were paired with the original traumatic experience (e.g., loud noises of gunfire paired with witnessing a comrade fatally injured in wartime) are thought to come to elicit negative affect through the process of classical conditioning [10]. Future exposures to the trauma cue alone (e.g., loud noises alone) motivate avoidance/escape behavior, including substance misuse, to reduce the associated negative affect and thereby experience relief [10]. Avoidance/escape behaviors like substance misuse are thus negatively reinforced in individuals with trauma histories/PTSD as they remove the aversive experience of negative affect. Therefore, substance misuse is maintained as a self-medication type of coping response through operant conditioning processes where behavior is repeated when it is followed by desirable consequences, in this case, relief from negative affect.

Another theory that is relevant to understanding the links of trauma/PTSD with SUD involves the role of classical conditioning in the development of conditioned craving—a strong urge to use the substance in response to exposure to the conditioned cues. It has long been known that drug-related stimuli that are frequently paired with drug-taking can come to elicit a conditioned craving response through the process of classical conditioning [11]. For example, a needle and other drug use paraphernalia that are frequently paired with heroin use can come to elicit craving when presented alone, for an injection drug user. Similarly, for a substance user with a trauma history/ PTSD, the frequent pairing of trauma cues (e.g., intrusive memories of the trauma, exposure to external trauma reminders) with substance use, as explained by the twofactor learning theory above [10], can come to create strong associations between trauma cues and substance use [12]. The result is that such trauma cues can become conditioned stimuli that elicit a conditioned craving response when presented on their own [13]. For example, if a young woman with sexual assault-related PTSD drinks alcohol each time she has an intrusive memory about her sexual assault, such trauma cues can come to elicit a strong craving for a drink, which may motivate her alcohol seeking and maintain her alcohol use.

The study of the above putative mechanisms under controlled, laboratory conditions is crucial for a better understanding of the intertwined relationships between trauma/ PTSD and substance misuse. Specifically, the use of cue-reactivity paradigms allows researchers to examine how substance-related and trauma cues may come to elicit craving and/or negative affective responses through the conditioning processes described above.

The cue-reactivity paradigm is broadly defined as a lab-based method in which participants are exposed to a set of stimuli meant to elicit a "reactivity" response—that is, a change from baseline in response to the stimulus [14]. In the context of addictions research, stimuli may be substance-related cues, such as a syringe or other drugrelated paraphernalia for an injection drug user [15]; these stimuli serve as analogs for real-life stimuli which may evoke a craving response outside of the lab. Indeed, research in this area has shown that relevant drug-related cues presented in the lab can elicit a heightened craving response among substance users [16, 17]. More recently, cue-reactivity paradigms have been used to study conditioned craving as a possible mechanism underlying the relationship between trauma/PTSD and SUD [18, 19]. Indeed, extant research has shown that in-lab exposure to cues representing trauma reminders (e.g., a video of a violent crime) activates both substance-related craving responses as well as increased negative affect [20].

Craving has been measured in a number of ways in substance- and trauma-related cue-reactivity research, including with subjective self-report measures, such as the Desire for Drug Questionnaire [21], and measures specific to the substances used, such as the Alcohol Urge Questionnaire [22] and the Marijuana Craving Questionnaire [23]. Craving has also been measured more objectively in cue-reactivity studies, albeit less commonly than via self-report. Specifically, physiological measures, such as salivary flow and heart rate monitoring, are often used as a more objective proxy measure of craving [24]. Craving has also been further differentiated into reward-related craving (i.e., a desire for reward or stimulation from a substance) and relief-related craving (i.e., a desire for a reduction in tension or negative affect from using a substance) using certain self-report measures [23].

While cue exposure paradigms are homogenous in their goal to elicit some form of reactivity (e.g., change from baseline in craving or emotional state in response to the stimulus), the types of cues and paradigms used in this area of research have varied widely. For example, cues may be standardized across participants in the study or may be personalized to the individual's own trauma history details; cues may be presented through the use of script-driven imagery (i.e., audio recordings, such as a retelling of a traumatic event) or *in vivo* (i.e., physical objects, such as drug paraphernalia); and cues maybe a photo or video stimuli (i.e., a video of an assault).

Indeed, it is evident that cue-reactivity paradigms vary widely in design, are used in an expansive variety of contexts and with a wide range of populations, with many different outcomes used to capture cue-reactivity effects. Thus, in this chapter, we intend to scope the extant cue-reactivity literature in the context of PTSD-SUD comorbidity research to identify patterns and variations in methodology, measures, and outcomes used in this growing field.

#### **1.1 Aims and objectives**

Our first aim was to examine how cue-reactivity paradigms have been used in samples of substance users with trauma histories. Specifically, we were interested in how these studies lead to a further understanding of the mechanisms underlying comorbid PTSD-SUD. Second, we intended to examine the different types of cues

used within the cue-reactivity paradigm as well as the specific effects, strengths, and weaknesses of variations in paradigm design. Specifically, we compared the merit of personalized vs. non-personalized cues, as well as other cue variations, in PTSD-SUD cue-reactivity research (e.g., *in vivo*, imagery-based). Third, we sought to assess the use of several measures of reactivity that have been examined using the cue-reactivity paradigm (i.e., craving [subjective, objective], negative affect) used in PTSD-SUD research. Lastly, we examined the types of participants who have been studied using a cue-reactivity methodology (e.g., trauma-exposed vs. suffering from PTSD).


**1. Introduction**

When something shifts in the cosmos, it also shifts in a quantity we call energy. Although its exact definition is unknown, the term "energy" is frequently used to ability of a physical or biological system to describe the motion or change. Movement, heating, and chemical transformation are just some of the various changes that can be brought about by applying different types of energy. Energy is required for all actions, including those performed by humans. It's necessary for humans to do activities like walk, cook, heat, and light their homes, and operate motor vehicles. Mankind is a voracious energy consumer. On average, a young man's daily energy needs amount to roughly 2500 kcal (2.9 kWh) while he is actively engaged in physical activity. An annual energy cost of roughly \$106 is implied. The present annual worldwide energy use is close to 20,000 kWh per person. If this trend continues, men will consume 19 times more energy than they need to maintain their current level of health and

well-being. Over the past 100 years, humanity has seen a significant growth in energy use. While the annual energy consumption per resident was approximately 5800 kWh in 1890, it increased to 20,200 kWh in 1970. Since 1970, the amount of energy used per resident per year has decreased to the current level of 19,000 kWh. The evolution process that began roughly five centuries ago can be linked to the rise in energy use in the twentieth century. The eighteenth century's Enlightenment saw the development of the philosophy of human progress, which provided the framework for this procedure. The method was intended to examine the environment and how it could be modified to better meet the needs of those whose lives would become safer and more comfortable. Growing industrialisation and mass production, which required an increasing amount of energy, went hand in hand with this process. Coal was the primary energy source at the end of the nineteenth century. During this time, electricity—a brand-new and sophisticated kind of energy—was introduced in the industrialised nations. This kind of energy was quickly used extensively. In the early twentieth century, as a result of the enormous rise in electricity demand and the subsequent building of hydroelectric plants, hydropower became a significant source of energy. At the close of the twentieth century, the oil and gas industries began to play a considerable part as contributors to the world's energy supply. Present-day energy sources are dominated by coal, oil, and gas. These three forms of energy (coal, oil, and gas), generally known as fossil fuels, are referred to as "conventional energy sources." During this time, nuclear energy was introduced as a brand-new energy source. Numerous household items are inexpensive because of growing and more efficient mass production. Given the tremendous increase in product consumption, it's not surprising that we now refer to modern society as a "consuming society." The quest for and use of new, sustainable energy sources has become a major issue near the end of the twentieth century. The urgency of this problem is highlighted by the Earth's finite supply of fossil fuels and rising global demand for energy generation. The focus is shifting to renewable energy sources because of this. Every human action requires energy. When considering the production and consumption of energy by human civilization, an energy system can be used to explain it. The population, overall energy consumption, and the types and sources of energy that people consume make up the key elements of the energy system. The energy system at the beginning of the twenty-first century is characterised by the six billion people who occupy the globe and the 1,300,000,000 kW of total energy use.

Even now, the cost of producing electricity from renewable sources is higher than that of conventional ones. As a result, it is not yet economically feasible in industrialised nations to use renewable energy sources as electricity power sources on a large scale. The main driver of a developing market for renewable energy sources and favourable national regulations is certainly their positive effects on the environment. But for the two billion people who, in many parts of the world, do not have access to an electricity grid, power generated from renewable energy sources is already the option that has the lowest overall cost.

The definition of "energy transition" is the move away from carbon-based energy sources during the coming years [1]. Therefore, it is crucial to provide energy using sources that can be regenerated organically over time on a human timeline. Renewable energy is the name given to this type of energy, which is largely environmentally safe and sustainable. Recent technological advancements have made it easy to convert various types of renewable energy into other forms of energy (such as electricity and heat).

As a direct consequence of this, in 2015 the international community came together to adopt the Sustainable Development Goals (SDGs) as a component of the United Nations 2030 Agenda for Sustainable Development [2]. The objectives promise to end malnutrition, poverty, etc. Some of the objectives specified by the world community, such as the provision of clean energy, climate protection, and others, were energy-related. The seventh goal (SDG-7) aims to raise the proportion of renewable energy in total energy by the year 2030 and to offer clean, cheap, and contemporary energy services in all parts of the world. In addition, Sustainable Development Goals−13 aims to enhance immunity either through increasing the resistance of a number of countries or by educating and raising awareness among the general public.

This is due to the fact that every nation on earth is susceptible to the repercussions of climate change. The vast majority of the energy that is required to keep things moving in the atmosphere comes from the sun. This energy is emitted in the form of electromagnetic waves, which have wavelengths ranging from 0.2 to 4 m and are invisible to the human eye. A photon is the smallest quantifiable unit of an electromagnetic field. The current definition of a photon is based on studies conducted by Albert Einstein between 1900 and 1920 (which were based on studies conducted by the German scientist Max Planck). Gilbert Lewis is credited with being the first person to use the term "photon," which was first published in Nature in 1926. Solar irradiance is the amount of energy that is received from the sun at a certain location and time in the form of electromagnetic radiation. This energy is measured in watts. It is stated as a number, and the unit of measurement used to determine it is W/ m2 . One of the most important forms of renewable energy is the sun's rays, which are collectively referred to as "solar energy" by the general public. There are two primary categories of technology that exist to capture the sun's rays: active solar technologies, such as photovoltaic systems, and passive solar technologies, which encompass a wide range of practises and may include orienting a building to the sun. Active solar technologies include photovoltaic systems. Passive solar technologies include a wide range of practises. Active solar technologies include photovoltaic systems.


Introductory Chapter: Advancements in Wheat Research

*Abdul Manan, Usman Ali Ashfaq and Mahmood-ur-Rahman Ansari*

#### **1. Introduction**

Wheat is the most common food crop we grow. In 2018, it was grown on 214 million hectares, which is approximately 30% of the total land area sown to cereal crops. With an average yield of about 3.4 tonnes per hectare, 734 million tonnes of wheat were produced in 2018 [1]. Wheat's role in human nutrition is another way to show how important it is. Approximately 20% of our protein intake and 20% of our carbohydrate intake come from wheat. Also, wheat represents our most traded cereal [2]. In 2018, over 118 mt of wheat was exported, which was 40% of all cereal exports. Australia, which is a major wheat producer, has average yields of less than 2 tons/ha, whereas yields in the UK are normally somewhere around 7 tons/ha and 8 tons/ha and are well more than 10 tons/ha in several zones [3]. Early in 2020, New Zealand had the maximum wheat yield ever observed: 17.4 t/ha. In many other places, it is hard to get more than 1 t/ha. The wide range of wheat yields shows how different the places where wheat is grown [4]. Due to variable environments, breeding programs usually concentrate on specific target areas. Breeding of wheat has been done mostly by the general public around the world, with help from governmental bodies or farmer groups. However, this has gradually evolved as profit incentive in breeding has grown, particularly in the EU and countries like Australia in which there is a clear way to make money from the benefits of improved varieties [5].

#### **2. Recent developments in wheat for drought stress tolerance**

Early on, the breeders realized that making wheat mature at right time for growing season was the most important adaptation trait that had to do with yield. The most important thing that affects yield, or more accurately, yield potential, is how much water is available. To get the most out of the crop, breeders look for patterns that mature and develop throughout the growth period. There is usually, although not always a proper relationship between both grain yield and biomass, growers try to time the development of the plant to coincide with when there is enough water. In cool climates, planting in the fall gives plants time to grow roots before the cold weather of winter, and then they grow quickly in the spring and early summer. If the winters are too cold and there is a chance of freezing damage, growers need to select varieties that can be planted after the danger has receded. They should also endeavor to extend the planting season as late as possible before drought and heat stress slow growth. This is different from hot

season crops, whose growing season is cut short by killing frosts in temperate zones [6]. If there is enough irrigation water, the season can be extended into the summer. If there is not enough fertigation water, early maturing lines are needed. In Mediterranean-type climates, where it rains in the winter but is hot and dry in the summer, biomass can be built by planting in the fall and letting the plants grow over the winter. However, the plants need to be mature early enough to be harvested before every dry season.

It is well known how important it is to match maturity to the growing season, and so this attribute is usually well organized in existing projects by using genes and loci for earliness, vernalization, and photoperiod response. There might still be ways to change the various growth stages to better match the environment, but generally, the way elite varieties grow and develop makes sure that the crop could indeed take benefit of the times when there is enough water and then flower and have full seed before the end of the season. Even though adjusting development to the atmosphere has been important for increasing the yield of wheat, complications stem during unusual stages when the growth trajectory of elite varieties does not match the patterns of rainfall and temperature [7]. This problem is getting worse because the weather is becoming more unpredictable. Farmers know that some periods will be severe and that they may take a loss. However, good years can make up for this. The fact that bad years are happening more and more often is a big problem, and farmers are looking for varieties that will do well in good years but cause less damage in bad ones. Breeders try to solve this problem by looking for ways to use water more efficiently and reduce the effects of things that might make yield stability less stable.

#### **3. Recent developments in wheat for high temperature tolerance**

Wheat production is in danger from many environmental factors. For example, the last 10 years (2010–2019) were the warmest on record, and the steady temperature rise is thought to have caused many changes in the way the climate system works [8]. In its Fifth Assessment Report, the Intergovernmental Panel on Climate Change said that by 2050, the average global temperature could rise by 2–5°C, or even more, and rain trends are likely to become less consistent [9]. "High confidence" says that these changes, like more frequent extreme events, are having an effect on food security. Food insecurity has effects that reach far and wide. Hagel, who used to be the head of the US Department of Defense, said that changes in climate "can add a lot to the problems of global instability, hunger, poverty, and war." In 2018, climate was found to be a cause of "crisis-level acute food insecurity" in 26 of the 33 countries where it happened [10]. Since Russia, India, France, China, and the United States produce 50% of the world's wheat, "any weather shock or external shock to production in these countries will have an immediate effect on global prices and price volatility." Improving how efficiently food is made is seen as a key way to make food production more sustainable in the future. About half of the world's wheat is affected by excessive heat, and 20 million ha or more often have too little water [11].

Models show that there is a chance that crops in global "breadbaskets" could fail at the same time because of heat or drought, and variation in rainfall and temperature (including drought) are indeed blamed for 40% of the variation in the production of wheat from 1 year to the next. By the end of this century, severe water shortages are predicted in approximately 60% of the world's cereal growing regions, and each 1°C temperature rise is expected to decrease yield by a mean of 6% [12]. A few other

research and modeling research shows that increasing the level of CO2 in the atmosphere at least to some extent counteract the harmful effects of drought and heat stress, but the data are not constant [13]. Also, the models do not take into account the harmful effects of rising night-time temperatures, thermal shocks, unsteady rain patterns, and dietary components, which are not helped by higher CO2 levels.

#### **4. Recent developments in wheat for quality improvement**

Wheat can be used for many different things, and each of these needs different qualities. The most important is GPC (grain protein content), which is a key factor how well a grain makes bread and pasta. Farmers usually get more money for grains that are high in protein. Content of protein is the most important quality trait, but the type of grain protein and a number of other qualities, such as grain hardness, also affect how the grain will be used [14]. There are several ways that heat and drought stress can change the quality. Extreme stress can stop starch from forming, which makes the grain smaller. Even mild stress can change the balance between gliadin and glutenin proteins, which changes the quality of the grain. But heat and drought have the most important effect on quality through their relationship to GPC. GPC is a complicated trait that is strongly affected by the environment but also has a clear genetic part. Breeders often choose plants based on how much protein they have since this is such a big part of how much the grain is worth [15]. Not surprisingly, the most important environmental factor that affects GPC is the amount of N fertilizer applied, but there is also a negative relationship between GCP and yield in many environments. GPD stands for "grain protein deviation," which is a way that varieties can be different from the relationship between yield and GPC [16]. It has been suggested that breeders could use GPD as a selection target to get around or lessen the effect of the negative relationship. In a study done in Australia, the negative correlation was found to be the strongest in low-yielding environments that are stressed by heat and drought. Breeders in Australia seem to have chosen high-protein genotypes that do well in lowyield environments based on how well these genotypes limit biomass accumulation to save nitrogen for grain filling. Analysis of a large number of field trials in different environments has shown that breeders need to select under drought stress and limited N supply to maximize both yield and GCP in new varieties, and studies in Europe have shown that selecting based on GPD is also important [17].

#### **5. Future prospects**

Way forward in "Climate Change" conditions is to produce wheat cultivars having multiple favorable traits which may better mitigate the crop in stress environment. The wheat plants may be stronger to tolerate various biotic as well as abiotic stresses along with better nutritional value, as food security and safety are both equally important. What we need now is to produce wheat plants having temperature, drought, salinity tolerance as well as more protein contents so that plant may be grown healthy under adverse environments along with more nutrition in terms of protein, carbohydrates, etc. The breeders are highly recommended to include all possible factors contributing toward climate change in their breeding programs while developing new wheat cultivars.

*Wheat - Recent Advances*

#### **Author details**

Abdul Manan, Usman Ali Ashfaq\* and Mahmood-ur-Rahman Ansari Department of Bioinformatics and Biotechnology, G.C. University, Faisalabad, Pakistan

\*Address all correspondence to<EMAIL_ADDRESS>
© 2022 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, provided the original work is properly cited.

*Introductory Chapter: Advancements in Wheat Research DOI: http://dx.doi.org/10.5772/intechopen.108193*

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#### **Chapter 2**


**1. Introduction**

H13 steel is widely used as a kind of hot die steel. It can be used for manufacturing various hot extrusion and forging dies [1,2] because of its high thermal strength, hardness, abrasion resistance, toughness, good heat resistance, and fatigue performance. But the surface performance will be significantly reduced if the H13 steel mold is exposed to high temperature for a long time [3–5]. Laser cladding technology can effectively improve the surface performance of the metal, but the process of cladding is affected by many factors. If only a single experimental study is carried out, the work efficiency will be low and resources will be wasted [6]. By combining computer simulation and experiment, the research cycle can be greatly reduced and the efficiency can be improved [7].

In the past two decades, scholars domestic and abroad have established numerous laser cladding simulation models and conducted relevant studies [8]. Kong et al. [9] adopted the enthalpy-pore method to deal with the phase transition phenomenon in the cladding process, adopted the horizontal set method to track the movement of the molten pool. The forced convection and thermal radiation on the surface of the cladding layer were incorporated into the simulation model, while the heat transfer process in the laser multilayer cladding process of H13 section steel was studied. Liu Hao et al. [10] developed a simulation model of laser cladding temperature field for simultaneous powder delivery.

**Citation:** Yao, F.; Fang, L. Thermal Stress Cycle Simulation in Laser Cladding Process of Ni-Based Coating on H13 Steel. *Coatings* **2021**, *11*, 203. https://doi.org/10.3390/ coatings11020203

Academic Editors: Pradeep Menezes and Pankaj Kumar

Received: 2 November 2020 Accepted: 4 February 2021 Published: 10 February 2021

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

**Copyright:** © 2021 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/).

The model processed the additive effect in the entire cladding process through the life and death element method, the shielding effect of the powder flow on the high-energy laser beam and the heat transfer of the laser beam in the powder conveying process were considered by calculating the shading rate [11–15].

Kar and Mazumder [16] proposed a one-dimensional conduction model to determine the alloy composition and cooling process. Hoadley and Rappaz [17] developed a twodimensional model to calculate the steady-state temperature in the laser cladding process, which gave a quasi-steady-state numerical model of the substrate temperature field. The calculation takes into account the changes in the liquid molten pool, the gas–liquid for the shape and position of the free surface, in order to simplify the model, it is considered that the substrate melts very little and uses the line energy form of the laser, so that the approximate linear relationship between the laser power, the scanning speed, and the thickness of the repair layer is obtained. Han et al. [18] solved the two-dimensional fluid and energy equations, predicted the temperature distribution and geometry of the molten pool during the laser cladding process. Cho and Pirch [19] published a three-dimensional steady-state finite element model of coaxial powder feeding. A self-consistent method is used to calculate the temperature field and coating shape. The obtained temperature gradient and cooling rate are used to predict the coating solidification structure. Jendrzejewski [20] discussed the influence of the preheating temperature on the temperature field and stress field of the repair layer, and adopted a linear approximation to its temperature characteristics. After preheating, the thermal stress value of the substrate repair layer reduced from 1800 MPa to 900 MPa, and got a crack-free repair layer. Toyserkani [21] et al. developed a three-dimensional transient finite element model of coaxial powder feeding. The coating is a multilayer structure, its width and height are determined by the area of the previous layer and laser powder. The model ignores the effect of surface tension and gravity on the shape of the coating. He [22,23] et al. studied the three-dimensional numerical model of the molten pool temperature and fluid flow during the laser cladding process of H13 steel, and used the level set method to simulate the molten pool. Kovacevic [24] and others at the Laser Aided Manufacturing Center of Southern Medical University USA used ANSYS to establish a finite element model. The law of temperature distribution and cooling rate in the molten pool under positive and negative defocusing conditions was studied. Compared with the Gaussian laser beam, it is found that the hollow laser beam (defocus) can effectively prevent the center of the molten pool from overheating, but the model does not consider the powder input impact when it reaches the molten pool. Parisa Farahmand studied the single multi-layer temperature field, strain stress field, and pool size evolution rule for laser cladding [25]. Gao W calculated the temperature variation, cooling rate, and solidification rate at the solid/liquid interface, but he did not consider the effect of Marangoni convection on the weld pool [26]. The Indian Institute of Technology and Monash University used H13 tool steel as the matrix to perform a single-pass laser cladding of CPM9V powder. It was found that the surface hardness of the cladding layer under single-layer and multi-layer conditions are the same. Researchers from Harazmi University in Tehran, Iran and Kaye Nasir Tutsi University of Technology in Tehran, Iran, used ABAQUS to simulate the laser cladding process of WC powder on the surface of Inconel 718. Analyzing the temperature field and residual stress distribution, it is concluded that the laser power and scanning rate have a greater influence on the dilution rate and residual stress of the cladding layer. The increase of input energy increases the residual stress of the cladding layer and the number of cracks decreases [27].

In this study, a planar continuous heat source model was used to conduct numerical simulation on the single-pass laser cladding process of H13 steel based on COMSOL software, the optimal process parameter scheme was determined, the thermal stress and thermal cycle curves were drawn and analyzed, which are used to study the influence of thermal stress cycle on the cladding layer, the residual stress of the cladding layer is also simulated.


*3.2. Chromatographic Conditions*

The mobile phase consisted of acetonitrile:water (62:38 *v*/*v*) containing 25 mM of TBA-Br bu ffer. After mixing, mobile phases were filtered through a 0.45-μm filter and degassed before use by an ultrasonic cleaner (Sonorex Digitec, Bandelin, Berlin, Germany). Chromatographic conditions were set at a constant flow rate of 1 mL/min in isocratic mode, the injection volume was 20 μL, the column was maintained at room temperature (20 ± 2), and the detection wavelength was set a 236 nm. Dissolved snSW GAP was pre-treated before injection, with a dilution of 60 mM of TBA-Br in a proportion of 1:3, allowing us to achieve ion pairing (IP) with a desirable k. This IP-RP-HPLC method was properly developed and validated according the ICH Guidance for Industry Q2 (R1) through several parameters, namely specificity/selectivity, linearity, precision, accuracy, range, limits of detection (LOD) and quantification (LOQ) (Tables S1 and S2) [40]. Concerning the leaching water samples, a di fferent proportion of the mobile phase was used (50:50 *v*/*v*), in order to better visualize the signal of GAP without interference.