**Abstract**

Adsorption is an important technique that significances the characteristics of porous solid materials and fine powders. The importance of porous solid materials and fine powders has been recognized when porous coal used for various applications such as catalysis, separation, isolation, sensors, chromatography, etc. Herein, the synthesis of mesoporous activated carbon derived from agricultural waste using TiO2. The TiO2-modified carbon was characterized employing scanning electron microscope (SEM), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, powder X-ray diffraction (pXRD), Brunauer–Emmett–Teller (BET) surface area analyzer and X-ray photoelectron spectroscopy (XPS). The obtained results suggested that the TiO2-modified carbon could be a potential material for various application like dye removal, metal removal and allied areas. This book chapter describes the commonly used classifications of porous bulk materials and also reported here the characterization of porous solid materials and fine powders with special reference to the evaluation of the surface area, pore size distribution and thermodynamic parameters of the different mesoporous material, at various scales of resolution using relevant techniques. These materials comprise several levels of structures that of the mesopores, micropores as well as macropores. The apparent topography analysis of these materials, of various pore diameters, synthesized in our laboratory has been determined at various scales with the help of various characterization techniques.

**Keywords:** Titanium Dioxide, Mesoporous Materials, N2 adsorption–desorption isotherm, Capillary (or pore) condensation


*2.3. Linkage Mapping and Statistical Analysis*

Of 893 SNPs segregating in the RIL population, 128 high quality SNPs were selected for the linkage map construction after excluding SNPs with missing rate over 10%, significant segregation distortion (Chi-square test *p*–value < 0.05), or overlapping genetic positions. The composite interval mapping was implemented using QTL IciMapping version 4.1 [21] with the threshold LOD (logarithm of the odds) score of 3.0. The same program was also used to estimate the additive e ffects and the phenotypic variation explained by each QTL at the peak LOD. The mean comparisons of DH between the RILs with di fferent allelic combinations of the identified QTLs were conducted by the Duncan's multiple range test using SAS version 9.4 (Cary, NC, USA). Three-way factorial ANOVAs were conducted to study the main e ffects of the three DH QTLs and their two-way and three-way interactions using SAS version 9.4.

### *2.4. Sequencing and Marker Analysis for Hd16, Hd1, and Ghd7*

The coding regions of *Hd16*, *Hd1*, and *Ghd7*, the candidate genes underlying the three DH QTLs from the Koshihikari × Baegilmi RIL population, were sequenced to search polymorphisms between Koshihikari and Baegilmi. The tenth exon of *Hd16* was amplified by polymerase chain reaction (PCR) using the primers and conditions described in Supplementary Table S1. The two exons of *Hd1* and the two exons of *Ghd7* were amplified by PCR as described in [22]. Sequencing of the PCR products was performed by Macrogen (Daejeon, Korea). To search polymorphism in the promoter region of *Ghd7*, the 2 kb upstream region of *Ghd7* from Koshihikari and Baegilmi was sequenced using the customized sequencing service at Macrogen (Daejeon, Korea). Molecular markers to di fferentiate the three main polymorphisms in *Hd16*, *Hd1*, and *Ghd7* between Koshihikari and Baegilmi were developed (Supplementary Table S1) and used to screen 295 Korean rice cultivars released in 1979–2017 by NICS, Rural Development Administration.


# **Vehicle and Traffic Safety**

Edited by Guzek Marek, Rafał Jurecki and Wojciech Wach Printed Edition of the Special Issue Published in *Energies*

www.mdpi.com/journal/energies

**Vehicle and Traffic Safety**


**1. Introduction**

Our daily life on Earth requires the production of large amounts of energy. The energy is produced mainly in the forms of electrical energy and mechanical energy as a result of liquid fuels and gases combustion in engines in various types of vehicles. Unfortunately, the various types of useful energy also cause the production of a huge amount of heat. Moreover, these useful energies are eventually converted to heat energy in machines, vehicles, and devices. An important question arises here—whether this release of a large amount of thermal energy is comparable to solar energy and can it significantly affect the global temperature and climate change. In this paper, the thesis was verified whether the heat emission, which is the final result of energy generated by our civilization, has an effect comparable to that of greenhouse warming. The greenhouse effect is well known and is comprehensively presented in many papers—among others [1–4]. However, the effect and greenhouse gas emission have not been discussed in the presented work so far.

Nuclear and fossil fuel power plants are thermal power stations and have a maximum efficiency of around 40%. It means that during the production of electrical energy, around 60% of nuclear or chemical energy in fossil fuel is converted to heat energy and is emitted directly into the atmosphere and water (seas, lakes, rivers). Thus, most of the energy contained in any fuel is lost, but there is currently no technically more efficient way to generate electricity. Unfortunately, that also applies to the combustion of biofuels. Wind and water power plants have much higher energy efficiency, and the production of electricity is accompanied by a low heat emission. Much more information about the energy conversion efficiency in thermal power stations is presented in the papers [5–7].

However, regardless of the way how electricity is produced, almost all electricity is ultimately turned into heat. It may seem surprising, but the following analysis proves this thesis. Electrical energy is distributed to different electricity consumers—factories, buildings, hospitals, railway electrification systems, etc. For example, any computer consumes electrical power and uses it to perform calculations, which is accompanied by heat production in semiconductor components (microprocessors, transistors, diodes, resistors). In practice, considering the field of physics, all the electric power in any computer is finally converted to heat. In a fridge, an electric motor drives a heat pump, which pumps out heat from inside the fridge to the outside. According to the principle of energy conservation, the heat energy released into the atmosphere (outside) is equal to the sum of heat energy collected from the fridge interior and the consumed electricity. A very similar situation occurs in any device. While an electrical train moves, electric motors cause acceleration driving at a constant velocity and partial energy recovery during braking. When the velocity of the vehicle is constant, all the consumed electrical energy compensates the work of friction forces in mechanical components (in bearings, etc.) and of air resistance forces. The friction in the components causes their heating, and air resistance causes the heating of the train's surface and air. The same situation occurs in cars. In a modern petrol engine, the chemical energy in the fuel is converted to heat (about 60%) and useful mechanical energy (about 40%). All mechanical energy is used to compensate friction forces and air resistance, so always a heat is produced. Thousands of various devices and machines can be considered in which the energy would finally be converted into heat—similar to what it is shown in Figure 1.

**Figure 1.** Electrical energy changes into other forms of energy and makes useful work, but almost 100% is finally converted to heat energy (own study).

Consequently, sooner or later, almost 100% of electrical energy or chemical energy in fuels is finally converted to heat energy. To determine the global heat production, it is necessary to calculate the global production of electricity and petrol fuels.


**2.4 Fruit characters**

The improvement in fruit traits including shape, size, and color is an important target in cucumber breeding. The fruit traits like fruit weight, length diameter and number of fruit per plant are directly related to yield. The other traits like shape index (length: diameter and length/stalk ratio), fruit skin (size of spines, dull or uniform fruit color) and fruit bitterness decides the market value of fruits which are important particularly for slicing cucumber [51]. A single recessive gene controls fragrance in cucumber [52], fruit color traits were controlled by two major genes, single recessive gene, (*w*), was identified that controls white immature fruit color [53], single recessive gene controlled the inheritance of quantity of beta-carotene [54]. Green flesh color is one of the most important and commercial trait of cucumber fruit was controlled by a major effect QTL [55]. The bent characters of the fruit were quantitative inheritance controlled by multiple genes and major genes [56]. Twin fused fruits were controlled by single recessive gene [57]. Two loci controlling fruit bitterness in cucumber [24–26]. The QTLs were also identified in cucumber for several economic traits including fruit spine, skin colors, fruit netting, fruit size, hollow size, flesh thickness variation [58], fruit carpel number, sex expression, fruit length, fruit diameter, fruit shape, fruit number, and powdery mildew resistance [28, 29].


**3. Antidiabetic activity of mushroom biomolecules**

Mushrooms are fungi that either grow above or below the ground. These are the macro fungi that can be easily seen with the naked eye. Mushrooms have been used since ancient times by the people of India and China or their medicinal properties. Nowadays many countries are consuming mushrooms for not only their unique flavor but also for their culinary effects. As many studies have revealed that mushrooms are rich sources of: proteins, carbohydrates, vitamins (B1, B2, B12, C, D, and E) and minerals like Mn, Mg, Se, Ca, Na, Cu, K, and Fe [38]. These nutritional factors in mushrooms have made it very efficient to fight diabetes. In vitro and in vivo studies have shown that the extract of mushrooms can reduce the expression of proinflammatory cytokines, induced by lipopolysaccharides which further improved the glucose uptake in skeletal muscle cell lines [39].

One of the most active biomolecules of mushrooms is β-glucans, a polysaccharide that can protect the pancreatic tissue from damage and restore the function of b-cells which helps to lower the blood glucose levels [40]. The low energy, lack of cholesterol and fats, less carbohydrates, and high minerals, proteins and vitamins made mushrooms an ideal food for diabetic patients. The consumption of mushrooms for a few days only can help to manage the low-density lipoproteins, total cholesterol, high-density lipoprotein, triglycerides levels in serum [10]. Besides bioactive molecules, mushrooms are very good in antioxidants activity and are also a good source of dietary fibers and water. Some of the most culinary properties containing mushrooms are *Agaricus bisporus, Agaricus subrufescens, Cordyceps millitaris, Cordyceps sinensis, Grifola frondosa, Ganoderma lucidum, Phellinus linteus, Pleurotus flabellatus, Pleurotus citrinopileatus, Pleurotus ostreatus, Poria cocos* [10, 41]. Extracts of Ganoderma lucidum contain: polysaccharides, triterpenoids, proteoglycans, and proteins which have been shown to reduce blood glucose levels. The proteoglycans of *G. lucidum* inhibit the tyrosine phosphatase 1B protein in diabetic patients. *G. lucidum* has proven to be very effective in controlling diabetes. Moreover, the triterpenoid from *G. lucidum* inhibits the aldose reductase and a-glucosidase enzymes which are responsible for the elevation of postprandial glucose levels [42]. Polysaccharides from *G. atrum* (PSG-1) increase insulin sensitivity and lower the serum lipid by increasing and decreasing the expression levels of Bcl-2 and Bax, respectively in pancreatic cells [43].

### *Mushroom; Chemistry, Bioactive Components, and Application DOI: http://dx.doi.org/10.5772/intechopen.104182*

Heteropolysaccharides are one of the bioactive molecules of Pleurotus ostreatus that control diabetes by activating the Glycogen synthase kinase 3 (GSK3) by phosphorylation and facilitating the translocation of glucose transporter type 4 (GLUT4) in streptozotocininduced diabetic rats [44]. *Lentinula edodes* promote the growth of gut microbiota, which play a very important role to balance the energy in diabetic patients. Another mushroom, *Hirsutellas inensis* shows antidiabetic, antiobesogenic effects in high-fat-diet feed-mice by modification of the components of gut microbiota. The polysaccharides and fibers of mushrooms act as prebiotics that helps in the treatment of diabetic patients [45]. Recently, researchers have found the potential effects of mushrooms in diabetic nephropathy conditions. Polysaccharides from Auricularia auricula are very helpful in promoting the oxidation of glucose. This polysaccharide protects against diabetic nephropathy by the regulation of creatinine, inflammatory factors, blood urea nitrogen, and urine protein. Polysaccharides isolated from *Flammulina velutipes* provided protection against reactive oxygen species (ROS) and reduced the level of malondialdehyde (MDA) in the kidney. The studies have also revealed that the proteoglycans from Ganoderma lucidum can restore kidney function by providing antioxidant activity [46]. According to a study conducted by Chou, Kan, Chang, Peng, Wang, Yu, Cheng, Jhang, Liu and Chuu [47], low molecular weight polysaccharide of *Inonotus obiquus* (LIOP) significantly reduces the expression of NF-jB and Transforming growth factor-beta (TGF-b) in a dosedependent manner [48]. They find that LIOP treatment can improve glucolipotoxicity induced renal fibrosis in diabetic nephropathy mice. *Hypsizigusm armoreus* have been used to examine its protective effect on the liver, kidney, and pancreas. The spent mushroom compost polysaccharide (SCP), its enzymatic lysates (ESCP), and acidbased hydrolyzed SCP (ASCP) were tested in streptozotocin-induced mice and found that it increased the: catalase, superoxide dismutase, and glutathione peroxidase activity whereas, it reduced the lipid peroxide and malonaldehyde levels [49]. a-glucosidase inhibiting polysaccharide (ePS-F4-1) with triterpenoids had been purified from Coriolus versicolor. Another bioactive molecule, MT-a-glucan (polysaccharide) from Grifola frondosa increases the expression of Interleukin-2 (IL-2) and prevents the injury of b-cells [50]. Submerged cultured mycelium of Agaricus brasiliensis and *G. lucidum* has shown a protective effect on red blood cells (RBCs) in Streptozotocin (STZ)-induced diabetic rats [51].


*3.1. Crop Performance Characteristics*

Crop performance characteristics such as tradable yield, number of fruits and fruit weight were influenced by both scion and rootstock, whereas variation in fruit shape was dictated strictly by the scion genotype in both years of experimentation (Table 1). The relative effects of scion cultivar and rootstock on all yield characteristics varied between years, with rootstock rendered less influential in the second year. Rootstock effect was most pronounced on tradable yield whereas fruit number, fruit weight and fruit shape were influenced overwhelmingly by cultivar. Cultivar × rootstock interaction was non-significant for all yield characteristics as scion and rootstock ranking remained unaltered between years. Tradable yield was highest in the large-fruited diploid Pegasus, which did not differ significantly, however, from that of the mini triploid cultivars Petite and Extazy. Yield was notably low in the diploid cultivar Vivlos, which was lower than the average yield of the mini triploid cultivars by 37% and 38% in the first and second year, respectively. Fruit weight was lowest for Extazy (3.2 ± 0.2 kg) but invariable (4.2–4.4 kg) across the rest of the mini scions. Inversely, the highest number of fruits per hectare was obtained from Extazy and the lowest from the large-fruited Pegasus. Low fruit weight combined with low number of fruits, tantamount to low yield, was evidenced only in Vivlos. The choice of rootstock had a consistent effect in both years on yield, number of fruits per hectare and fruit weight, which were in all cases higher with TZ148 than Festival.

**Table 1.** Mean comparison for yield, fruit number, fruit mean weight, fruit shape (meridian/equatorial diameter), at harvest of watermelon fruit from cvs. Petite,

#### *3.2. Physical Quality Characteristics of Watermelon Fruit*

Physical quality characteristics of watermelon fruit, such as rind thickness, pulp firmness and pulp color, were predominantly determined by the scion cultivar, which accounted for most of the variance observed in these traits (Table 2). Rootstock effect was most pronounced on pulp firmness whereas storage had its greatest effect on rind thickness and the colorimetric values of the pulp. In both years, the thickest watermelon rind was found in the mini triploid cultivar Extazy and the thinnest in the mini diploid Vivlos. Rootstock had a significant effect on rind thickness only in the first year of experimentation whence the interspecific rootstock TZ148 induced a thicker rind than the Lagenaria rootstock Festival. Pulp firmness was highest in the triploid mini cultivars Extazy and Petite and lowest in the diploid cultivars. Rootstock had a significant effect on firmness with TZ148 imparting higher firmness than Festival by 28.9% and 31.3% in the first and second year, respectively. The effect of storage on firmness was marginally significant in both years with mean firmness reduced after 10-day storage at 25 ◦C by merely 8.0% and 5.5% in the first and second year, respectively. The colorimetric variables of the pulp were influenced mainly by scion cultivar and less so by rootstock and storage. Lightness (L\*) was highest in Pegasus and Vivlos and lowest (darkest pulp) in Extazy and Esmeralda. As denoted by chroma values (C\*), the pulp was most intensely colored in Extazy and Vivlos and least colored in Esmeralda, Petite and Pegasus. Similar cultivar ranking was observed in both years for the intensity of redness denoted by colorimetric parameter a\* (data not shown). Chroma was also marginally higher in response to rootstock TZ148 than Festival but only in the first year of experimentation. The narrowest hue angles denoting the most reddish color were obtained from Extazy and Pegasus, while the widest hue angles denoting the least reddish hue were obtained from Esmeralda. During 10-day storage at 25 ◦C, there was a slight darkening of the pulp (reduced L\*), but also an increase in chroma and a widening of hue angle denoting a more intense color but also a slight color transition toward orange-red hue.

**Table 2.** Fruit rind thickness, pulp firmness, pulp CIELAB color components (Lightness—L\*, Chroma—C\* and Hue angle—h), lycopene content, total soluble solids (TSS), and citrulline content in watermelon fruit of cvs. Petite, Vivlos, Pegasus, Extazy and Esmeralda grafted on TZ148 and Festival rootstocks and stored for 10 days at 25 ◦C. Values represent means ± SE.

*Agronomy* **2020** , *10*, 1396

### *3.3. Compositional Characteristics of Watermelon Fruit*

Pulp lycopene content correlated significantly with pulp chroma in both years (ryear1 = 0.53, *p* < 0.001 and ryear2 = 0.72, *p* < 0.001). Scion cultivar effect was the most influential on pulp lycopene content compared to rootstock and storage effects (Table 2). The range of lycopene content in the scion cultivars was widened by Extazy, which attained 95% and 57% higher lycopene than the mean content of the rest of the cultivars in year1 and year2, respectively. The outstanding lycopene content of Extazy (102.8–112.3 μg g−1) also rendered the differences among the rest of the cultivars non-significant. Variation among the rest of the cultivars was indeed limited, though it is worth noting that the mini diploid cultivars Esmeralda and Vivlos had the most variable lycopene content between years. With respect to rootstock, in both years the mean lycopene content of the scions grafted onto interspecific rootstock TZ148 was higher than that obtained on the Lagenaria rootstock Festival. Storage at 25 ◦C for 10 days increased pulp lycopene in both years, however this effect was more pronounced in the first year. The content of the pulp in the non-essential amino acid citrulline was influenced by the scion cultivar and by storage but not by the choice of rootstock (Table 2). Variation in mean citrulline content among cultivars ranged from 2.9 ± 0.1 μg g−1 f.w. in Pegasus to 3.7 ± 0.1 μg g−1 f.w. in Petite. During storage, the citrulline concentration in the pulp declined, however the reduction was of limited scale, amounting to 6.1%.

The TSS content of the juice was influenced mostly by cultivar and storage and least by rootstock (Table 3). Variation in TSS among cultivars was more limited in the first year compared to the second. In both years, Extazy had the lowest TSS (9.8–10.5%) whereas Pegasus and Vivlos had the highest (11.0–11.4%). Overall, diploid cultivars had higher TSS than the seedless cultivars. Rootstock had no effect on TSS during the first year and only a marginal effect during the second when TZ148 resulted in slightly lower TSS than Festival. Very similar effects to those on TSS were observed with respect to the total sugar content of the juice (Table 3). Extazy had the lowest sugars and scions grafted on Festival yielded slightly higher sugars than those on TZ148. Mean total sugar content declined significantly with storage in both years with a sharper drop observed in the first than the second year. Fructose, glucose and sucrose varied significantly in response to storage and scion cultivar and were least affected by rootstock. Fructose was higher in the mini diploid cultivars Vivlos and Esmeralda than the mini seedless Extazy and Petite. Fructose was not affected by rootstock in either year. Storage had a significant effect on fructose which was reduced after 10 days at 25 ◦C by 12.4% as a two-year mean. Glucose was also lowest in Extazy and Petite and highest in Esmeralda and Vivlos. Significant cultivar–rootstock interaction was observed for glucose as Festival induced higher glucose content than TZ148 in the first year whereas the opposite was observed in the second year. Storage reduced glucose by 39.7% and 42.3% in the first and second year, respectively. Sucrose was highest in Pegasus and Extazy in the first year and in Pegasus and Petite in the second. Among the mini cultivars, sucrose in proportion to the reducing sugars was more abundant in the seeded than the seedless cultivars. Significant cultivar–rootstock interaction was observed for sucrose as TZ148 induced higher glucose content than Festival in the first year whereas the opposite was observed in the second year. As opposed to the levels of reducing sugars, sucrose levels increase postharvest significantly, amounting to an average increase of 57.2% between the two years. Variation in the proportions of the three sugars was reflected in the sweetness index of the pulp. The highest sweetness index was observed in Vivlos and Esmeralda and the lowest in Extazy. The watermelon pulp acidity as reflected in the juice pH showed limited variation across cultivars, with no differences observed in the second year. Rootstock affected juice pH only in the second year with slightly more acidic juice obtained from watermelons grafted onto TZ148. A significant drop in acidity was observed in both years postharvest.

Petite, Vivlos, Pegasus, Extazy and Esmeralda grafted on TZ148

 degrees of freedom. Significant effect the 0.05 level, 0.01 level, 0.001 level. Means each column followed by different letters denote significant accordingtotheTukey–KramerHSDtest.

*Agronomy* **2020** , *10*, 1396

#### **4. Discussion**

Fruit morphometric characteristics such as weight and shape were the ones affected least by the choice of rootstock. Fruit shape in particular was a trait defined almost exclusively by the scion genotype. These findings corroborate previous works demonstrating the limited variation encountered in these traits in response to different rootstocks and also between grafted and non-grafted material [1]. By contrast, crop performance was strongly influenced by the choice of rootstock. In this respect, the higher yield obtained on *Cucurbita maxima* × *C. moschata* interspecific rootstock TZ148 reflects the vigorous habit of interspecific rootstocks in comparison to the weaker *Lagenaria* rootstocks, such as Festival. These findings underpin previous reports on the superior crop performance imparted by interspecific rootstocks, provided the absence of physiological incompatibility between scion and rootstock [14–16]. Fruit weight and fruit number incurred a limited rootstock effect. Cultivar genotype largely defined variation in these traits with the large-fruited diploid Pegasus producing higher yield than the mini cultivars, of which the triploid ones were more profuse than the diploid ones. Moreover, watermelon yield may present significant annual variation, as presently demonstrated by all scions on both rootstocks, which has been attributed by previous researchers to the variability of climatic and soil conditions [17,18]. It is noteworthy, however, that mean yield varied between years by 12.2% on TZ148 compared to 36.3% on Festival, which is an indication of the stable vigor afforded by interspecific rootstocks. Nonetheless, all of the scion–rootstock combinations examined exceeded the regional yield average of 52 tons ha−1 in both years [19,20].

Morphological and visual characteristics of watermelon fruit may substantially influence the perception of quality and ultimately consumer choice. Rind thickness is a morphological trait previously described as responsive to cultural practices that affect maturation, including grafting [1,11]. As the rind grows progressively thinner with maturation, watermelon harvest maturity is a defining factor. Contrasting literature on the impact of grafting on rind thickness may thus be interpreted partly in the context of rootstock effects on the ripening process but may also be attributed to the absence of strict maturity standardization during sampling. The current study corroborates that rootstock effect on watermelon rind thickness is generally limited compared to the effect of the scion cultivar [21]. Little emphasis has been given previously on the postharvest change in watermelon rind thickness [19,22]. The current study indicates that it is reduced during storage, which renders the impact of rootstocks on rind thickness, presently evidenced in the thicker rind induced by interspecific TZ148 over *Lagenaria* rootstock Festival, significant for watermelon shelf-life.

Pulp firmness is a significant sensory quality trait of watermelon fruit shown to respond to heterografting on various types of rootstocks. Commercial interspecific (*C. maxima* × *C. moschata*) rootstocks tend to increase pulp firmness, as demonstrated by several previous studies [10,11,23,24]. Loss of firmness in response to heterografting has been more often reported with particular *Lagenaria siceraria* and *Cucurbita argyrosperma* rootstocks [25,26]. The present study focused on the impact of interspecific and *Lagenaria* gourd rootstocks on scions of differing ploidy, therefore homeograft and self-rooted controls were not used. It was nevertheless observed that the more vigorous interspecific rootstock TZ148 induced notably higher pulp firmness (30.1% higher as a two-year average) than the *Lagenaria* rootstock Festival, which underpins previous findings on the superiority of interspecific hybrids for this trait. Gourd rootstocks have had for the most part no effect or very limited and variable effect on pulp firmness [15,24,25,27]. Pulp firmness was also found significantly higher in seedless triploid cultivars compared to diploid ones despite the fact that texture analysis was performed not in the locular areas but around the core of the fruit using a set of eight probes in circular 42 mm-diameter arrangement [11]. Pulp firmness has been linked to increased density of parenchymatic cells containing higher alcohol-insoluble and water-insoluble cell wall fractions [28]. The higher firmness presently observed in triploid cultivars, noted also by certain previous researchers [29], might thus be related to higher density of parenchymatic cells bearing more abundant alcohol- and water-insoluble fractions, a hypothesis that warrants further investigation involving cell wall fractionation. Finally, the effect of storage on firmness was significant but limited compared to that of scion cultivar and rootstock. Nonetheless, previous work has demonstrated that sensory quality and shelf-life of watermelon is limited to less than two weeks under ambient conditions owing among others to declining pulp firmness, [1]. In light of this, grafting on interspecific hybrid rootstocks might present a significant advantage in terms shelf-life and the same might be the case for triploid over diploid scions.

Watermelon pulp color is configured principally by the accumulation of carotenoids during ripening [11,30,31]. Over 90% of the carotenoid content of red-fleshed cultivars accounts for lycopene, with about 10% being in the *cis* isomeric bioavailable form and the rest in the *trans* form [32]. The highly significant correlation of pulp colorimetry with lycopene content, evidenced in both years of the present study, is common among red-fleshed cultivars; however, pulp chromaticity may not always correlate significantly enough with lycopene content owing to the presence of β-carotene, which varies with cultivar, maturity and postharvest storage [1,33]. The presence of Extazy among the examined scions, which had an outstanding lycopene content (102.8 μg g−1 fw), confounded the effects of rootstock and storage compared to the scion effect. Nonetheless, scion genotype is the most determining factor for carotenoid composition of watermelon fruit with lycopene varying widely among red-fleshed cultivars (20–125 μg g−1 fw), presently exemplified by the triploid Extazy [32,34]. The current results, moreover, indicate that ploidy is not a determining factor for lycopene content since triploid cultivars diverged significantly (61.9–102.8 μg g−1 fw). Grafting, on the other hand, especially on *C. maxima* × *C. moschata* interspecific rootstocks [11,21,35,36] and less frequently on *L. siceraria* cultivars [37], has been found to increase lycopene content in watermelon fruit. In both years of the present study, the lycopene content of the scions grafted onto the interspecific rootstock TZ148 was higher than that obtained on the Lagenaria rootstock Festival. This might be attributed in part to a higher density of parenchymatic cells induced by TZ148 since lycopene is a fat-soluble membrane-bound pigment [11,28]. Finally, postharvest storage at 25 ◦C for 10 days increased pulp lycopene in both years of the present study, corroborating previous reports that lycopene synthesis continues and lycopene levels peak postharvest although watermelon is a non-climacteric fruit [1,19]. The postharvest increase in chroma (C\*) was accompanied, however, by a wider hue angle signifying a color transition toward the orange-red hue characteristic of over-ripening. This transition might stem from the conversion of lycopene to β-carotene or from lycopene degradation products [38].

Citrulline is arguably the most important bioactive molecule found in watermelon fruit after lycopene [39]. Previous work has demonstrated that grafting watermelon on interspecific hybrid rootstocks may increase citrulline concentration in the pulp compared to the non-grafted control [1]. The current study indicates that the choice of rootstock between an interspecific hybrid and a *Lagenaria* rootstock has no effect on citrulline. In fact, the greatest source of variation was the scion cultivar whereas limited decline in citrulline was observed postharvest. It appears therefore that the increase in citrulline content obtained with grafting vs. self-rooted watermelon is largely offset by postharvest decline, which was not previously reported for non-grafted watermelon. However, given the relative abundance of citrulline in watermelon rind, the thicker rind induced by TZ148 may provide more substrate for industrially extracting the non-essential amino acid citrulline that garners significant pharmacological interest [39].

The soluble solids content of watermelon juice is configured primarily by soluble sugars although non-carbohydrate components such as organic acids, water-soluble soluble pectins and pigments may also influence the refractive index of the juice [40,41]. In the present study, the TSS and the total sugars of the juice were influenced mostly by cultivar and storage. Diploid cultivars attained overall higher TSS and total sugars than the seedless cultivars, however all scions delivered TSS values near 10% or higher, which is considered a prerequisite for consumer acceptability [42]. Postharvest storage at ambient temperature resulted in a significant decline in TSS and total sugars, which renders the postharvest handling of watermelons critical for sensory quality, especially for triploid cultivars of lower sweetness. In this respect, Kyriacou et al. [1] highlighted in previous work the importance of optimal harvest maturity for watermelon grafted on vigorous rootstocks that delay ripening, when prolonged postharvest storage (>10 days) at ambient conditions is unavoidable. From a physiological point of

view, it is noteworthy that glucose and fructose levels decreased during storage as opposed to sucrose, which increased owing most probably to the postharvest activity of ripening-related enzymes such as sucrose synthase. This observation, in conjunction with the postharvest accumulation of lycopene discussed above, sheds new light onto the postharvest physiology of watermelon, otherwise considered a non-climacteric fruit.

The TSS and total sugars of watermelon were generally not decreased by grafting on most commercial *C. maxima* × *C. moschata* rootstocks [10,23,36], whereas scion response to grafting seems more rootstock-specific with *Lagenaria siceraria* cultivars and landraces [14,37,43]. The marginally lower total sugars content observed with TZ148 in the second year of the current study likely relate to the higher fruit load supported by this rootstock and a possible slight delay in ripening compared to the *Lagenaria* rootstock Festival. This is further supported by the higher hexoses-to-sucrose ratio observed with TZ148 in the second year, given that the common sugar motif observed during watermelon ripening is that of sucrose accumulating at the expense of hexoses [11]. At any rate, the non-significant or marginal rootstock effect on TSS and total sugars renders interspecific TZ148 an advantageous rootstock over *Lagenaria* Festival on account of higher yield, firmness and lycopene content.


**Abstract**

In order to overcome the challenges and limitations related to conventional maintenance and repair methods in structural composites during service, the concept of self-healing for polymeric materials has been developed in the last decades. Inspired by biological systems, ideal self-healing materials must be able to repair damages continuously during the service life of the component, recovering its performance. Several techniques have been proposed in the last years to manufacture self-healing polymers and fiber-reinforced composites to provide healing of microcracks in the composite structure without or with less intervention, extending service life and safety of the components and reducing maintenance time and cost. This book chapter proposes an overview of the most promising self-healing approaches for thermoset and polymer matrix composites developed in recent year.

**Keywords:** advanced materials, thermoset polymers, polymer matrix composites, self-healing, mendable resin

## **1. Introduction**

Polymers and polymer matrix composites (PMCs) have been extensively used for a variety of structural applications due their combination of high mechanical properties and light weight savings as major benefit. During service, the operating environment often exposes these materials to severe variations in mechanical loading and environmental conditions. Such conditions induce damages and can cause the formation of microcracks. These matrix damage can lead to the coalesce and growth of larger cracks, which compromise mechanical performance and integrity of the material inside its structure, where detection and external intervention are difficult and/or impracticable. Non-destructive testing methods are generally used for inspection of components during operation. However, internal microcracks can be difficult to repair [1, 2]. To overcome the challenges related to the repair of these internal damages in thermoset matrix and FRP, self-healing materials have been proposed in the decades as an alternative to conventional repair methods.

Ideal self-healing materials are designed to present the ability repair themselves, using resources inherently available to them. The recovery of performance can be full or partial and occurs during the service life of the component with minimal or no external intervention. These materials can provide the healing of invisible

microcracks in the composite structure and can be an alternative to non-effective conventional maintenance methods to extend service life and safety of the components in addition to reducing maintenance time and cost [1, 3, 4].

Inspired by biological systems, the self-healing of synthetic materials occurs in three steps. Initially, the healing mechanism is triggered by the damage. In the second step, the healing agent, that is, the material responsible to repair the damage, is transported to the damaged area. Lastly, the repair process takes place, recovering the crack. The time and efficiency of the recovery depend on the self-healing mechanism used [5, 6].

Different types of self-healing mechanisms are described in literature for all types of materials. Polymeric materials are reported as promising for self-healing, and the self-healing ability can be introduced by chemical modification or exposure to physical or thermal conditions. The glass transition temperature (Tg), the chain mobility, and the chemical structure are important parameters to be considered during the design of the self-healing system and can influence the success of the healing ability [7].

In this scenario, self-healing polymeric materials represent a new class of materials and have attracted great attention in the past decades. Studies have been developed to better understanding of the self-healing ability, the mechanisms, and how to overcome the challenges of processing and the limitations of each system. In the last decades, a significant increase in the amount of research about self-healing polymers is reported. **Figure 1** shows the growth of the number of papers published on the topic of self-healing polymeric materials since 2000.

Several mechanisms are employed to obtain self-healing polymeric materials and each mechanism presents advantages, limitations, and challenges in formulation. In this review article, principles and developments in self-healing thermoset matrix and fiber reinforced polymers were presented.

**Figure 1.** *Number of published papers according to science direct searched by "polymers self-healing".*


Preface

Present in soil, water, and geological organic deposits, humic substances are the most widespread organic compounds, naturally occurring from the physical, chemical, and microbiological transformation of biomolecules. Humic substances represent about 25% of the total organic carbon on the Earth and comprise up to 75% of the dissolved organic carbon in water, making them important for multiple environmental processes in both soil and aquatic systems.

Based on their solubility, humic substances can be fractionated into humic acid, fulvic acid, humin, and some microelements. Humic acid includes long-chain aggregates soluble in alkali, while fulvic acid is a mixture of short-chain compounds soluble in both acidic and alkaline solutions. Humin, in contrast, constitutes the non-soluble fraction of the humate. This classification is based only on superficial criteria and does not indicate chemical behavior or provide insights into chemical structures.

Humification, or the set of processes leading to humic substances, is a set of reactions occurring either in sequences or simultaneously and affecting at varying speeds an extreme diversity of substrates. These reactions are essentially biochemical in nature, but purely chemical processes can also be involved. Physical factors, such as temperature or the humidity of the surrounding environment, also determine the formation of humic substances at various stages. Humification, therefore, appears to be a complex process in which biological activity plays a major role in the short term, but the slow evolution of humic compounds due to external conditions may gradually modify the properties of the humus.

Despite many decades of extensive studies, the formation mechanisms of humic substances, as well as their structure, are still a subject of discussion and controversy. The content of this book revolves around the structure and dynamics of humic substances, their physicochemical and biological properties, and the technics of their extraction and characterization. The book also sheds light on recent advances and applications of humic substances in agriculture, environment, industry, and medicine.

**II**

**Chapter 8 139**

**Chapter 9 153**

Chemical Characteristics of Humic Substances in Nature *by Claudio Fernando Mahler, Nicoly Dal Santo Svierzoski*

Sewage Sludge to Fertilise Durum Wheat: Effects on Crop and Soil

*and Cassiano Augusto Rolim Bernardino*

*by Pilar Mañas and Jorge de las Heras*

**Abdelhadi Makan** Abdelmalek Essaadi University, Tétouan, Morocco

**1**

**Chapter 1**

**Abstract**

**1. Introduction**

non-soluble fraction of the humate.

Humic Substances: Prospects for

Use in Agriculture and Medicine

Humic substances are the naturally occurring biogenic, heterogeneous organic compounds resulting from the decomposition of plant, animal and microbial residues, over many thousands of years. Research into humic substances have found them to be beneficial not only for crop production, but for human and animal health also. Humic substances influence crop yields by affecting soil texture, water retention, nutrient buffering capacity and microbial diversity. Their stimulatory effects on plant growth and physiology can be ascribed to enhanced nutrient uptake, hormonal activity with root growth and proliferation, activation of antioxidant defense under various abiotic stresses. Furthermore, their potential to remove toxic pollutants from soil as well as aquatic systems might resolve the problem of degrading environment. Positive effects of humic substance on soil as well as crop without harming the environment make humic acid a sustainable solution for crop production. The antioxidant, immunomodulatory, anti-inflammatory, detoxifying and nutritional properties of humic substances opens up new avenues for their medical applications. Still, more research is needed to completely explore their potential. This chapter will summarize and review information about the prospects of using humic substances in agriculture and medicine.

**Keywords:** Humic substances, Fulvic acid, Humic acid, agriculture, medicine

Humic substances (HS) are soil-derived substances that form one of the vast reservoirs of organic carbon in nature. HS are primarily produced by physical, chemical and microbial degradation and transformation of plant and animal tissues (humification process) over millions of years. They constitute the bulk of organic matter of the soil – humus, peat, lignites and also brown coal. HSs may also be produced as a by-product of the synthetic oxidation reactions of phenolic compounds. Humic substances contain carbon, hydrogen, oxygen and nitrogen with small amounts of sulfur and phosphorus. They are a mixture of acids that can be fractionated on the basis of differences in their solubility into humic acid (HA), fulvic acid (FvA) and humin fractions, beside ulmic acid, and some microelements. Humic acid includes aggregates of long chain, high molecular weight compounds, soluble in alkali, while FVA is a mixture of short chain, low molecular weight compounds, soluble in both acidic and alkaline solutions. Humin, in contrast, constitutes the

Owing to their unique structural and chemical properties, humic substances make an excellent soil amendment. They offer beneficial impacts in terms of overall soil structure, water holding capacity and nutrient availability in the soil along with

*Priya Goel and Madhu Dhingra*

## **Chapter 1**