**10. Results and discussion**

### **10.1. Characterisation of fibers**

The dietary fibers used in this study have different water solubility characteristics: inulin is a soluble fiber, bamboo and wheat are insoluble fibers, apple is partially insoluble fiber, and psyllium forms a viscous dispersion at concentrations below 1% and a clear gelatinous mass at 2%. Chitosan is a fiber of a different origin, i.e. from animal source and is soluble in an acidic medium and flocculates in an alkaline medium. We used these fibers because they present different physicochemical behaviors that have been described in literature [144,4]. The commercial fiber compositions used in this study, regarding total, soluble and insoluble fractions, are shown in Table 4. Analysis for dietary fiber using the AOAC method 991.43 showed that wheat and bamboo have high amounts of insoluble fraction.

nd: no detectable

470 The Complex World of Polysaccharides

standard curve was developed [138].

**9.6. Statistical analysis**

**10. Results and discussion**

**10.1. Characterisation of fibers**

digestive simulation solution (10 mL) was mixed with 1.0 mL of reagent, tubes were incubated for 5 min in water bath at 37°C and developed colour were read in spectrophotometer (Spectronic 20 Genesys TM, Spectronic Instrument, USA) at 505 nm. Final reaction colour is stable for 30 min. Glucose calibration curve was carried out. The amounts of glucose used in

To determine calcium concentration a spectrophotometric method was used. Calcium reacts with 3.7 mmol/L cresolphtalein complexone (Cpx) at pH 11 (buffer 0.2 mol/L aminomethylpropanol (AMP) solution in 35%v/v methanol) (Wiener Lab Ca-color Kit, Argentina). Assays were carried directly in spectrophotometer test tubes: 50 lL Cpx were mixed with a plastic rod and absorbance was read in spectrophotometer (Spectronic 20 Genesys TM, Spectronic Instrument, USA) at 570 nm (internal blank), then 20 mL of each digestive mimicking sample were added, immediately mixed and read after 10 min. A

To determine iron concentration in the dialysates a spectrophotometric method was used, 500 μL of dialyzates was reduced with 2 mL of mercaptoacetic acid (succinic acid buffer, pH 3.7). Then, iron reacted with one drop of pyridyl bis-phenil triazine sulfonate (PBTS) producing a pink color due to the complex formed (Wiener Lab Fe-colour Kit, Rosario, Argentina). Absorbance was read on a spectrophotometer (Spectronic 20 Genesys Thermo Electron Scientific Instruments Corp., Madison, WI, USA) at 560 nm (internal blank). All glassware used in sample preparation and analysis was rinsed with 10% (v/v) concentrated HCl (37%) and deionised water before using, to avoid mineral contamination. A regression equation (y = 2.5333x + 0.0042, R2 = 0.995) derived from data generated from standards of FeSO4 was used to calculate iron concentrations in the samples. Iron retention percentages for each studied fibers were calculated as a percentage of the amount of iron measured in

Experiments were performed at least five times for each dietary fiber using freshly prepared yogurt. For total iron concentration in dialyzates, each individual sample was run in duplicate. Averages and standard deviations were calculated and expressed in each case as the mean ± SD for n replicates. Normality of the data was checked with the Lilliefors test. The influence of different dietary fibers on the retention percentages of glucose, calcium and iron were statistically analyzed by a one-way analysis of variance (ANOVA) (p < 0.05) to

The dietary fibers used in this study have different water solubility characteristics: inulin is a soluble fiber, bamboo and wheat are insoluble fibers, apple is partially insoluble fiber, and psyllium forms a viscous dispersion at concentrations below 1% and a clear gelatinous mass

the dialysed medium obtained with the control yoghurt without fibers [139].

find significant differences and Tukey's test to compare means.

this study correspond to available carbohydrates in the human mixed diet.

**Table 4.** Total, soluble and insoluble fiber content (g/100g) of employed fibers

Inulin presents only soluble fraction as expected. Psyllium and apple have both soluble and insoluble fractions. Apple fiber is characterized by a well balanced proportion between soluble and insoluble fraction [145]. The total dietary fiber content is 45.2% for psyllium, which is an acceptable value, taking into account that the supplier declared a 49.15% content for Plantago ovata seed husk in Metamucil preparation. Van Craeyveld et al. [146] reported 3.4% (dm) ash and 7.1% (dm) protein contents for Plantago ovata seed husks. The total dietary fiber content is 58.1% for apple, which is about 10–14% higher than the values reported by Sudha et al. [147]; however, this value was in accordance with suppliers. The chitosan used in this study has 98% of insoluble fraction and no detectable soluble fraction. Furthermore the characteristics of this biopolymer are a deacetylation degree of 89%, a viscosity of 120 mPa.s, 6.7 g% moisture and 0.67 g% ash content.

Plant fiber characterisations were completed with the study of Acid Detergent Fiber (ADF) and Neutral Detergent Fiber (NDF), lignin, cellulose and hemicellulose contents (Table 5). Apple presents the highest lignin content. Wheat fiber mainly has cellulose. Bamboo has proportional amounts of cellulose and hemicellulose, but compared with other fibers, has the highest hemicellulose content. These results are in accordance with their plant fiber origins and previous works [145-149]. Frutafit-Inulin was not analysed because its composition was ≥85.5% (w/w) of inulin, ≤9.5% of mono and disaccharides, ≤0.1% of ash with polymerisation degree ≥9 according to suppliers. Chitosan was not analysed either, because of its animal origin.

**Table 5.** Acid Detergent Fiber (ADF), Neutral Detergent Fiber (NDF), lignin, cellulose and hemicellulose (%) of fibers

Scientists who deal with animal nutrition usually use Van Soest's method to analyse feed. Scientists working on human nutrition use methods of the AOAC, because of their interest in soluble fiber. It is known that soluble fiber plays an important role in human health and the food industry. However, it could be useful in human nutrition to know the composition of insoluble fiber, as it is possible that insoluble fibers do not all have the same effect on human health. The NDF and insoluble fiber methods were applied to the same samples. Insoluble fiber includes hemicellulose, cellulose, lignin, cutin, suberin, chitin, chitosan, waxes and resistant starch. NDF includes hemicellulose, cellulose and lignin. Escarnot et al. [149] studied three wheat varieties and four spelt genotypes. They analysed three milling fractions from those grains for insoluble and soluble fiber contents, lignin, hemicellulose and cellulose. They found a very high correlation (r2 = 0.99) between the two methods, showing that NDF and insoluble fiber methods cover the same types of fiber. For insoluble fiber analysis, the NDF method is faster and more thorough.


**3.2 The** *E. coli* **genome**

The first complete *E. coli* genome sequence was the sequence of the K-12 MG1655 strain of *E. coli*, published in 1997. The sequenced strain has been maintained as a laboratory strain with minimal genetic manipulation, having only been cured of the temperate bacteriophage lambda and F plasmid. The published genome has 4,639,221 base pairs. Protein-coding genes account for 87.8% of the genome, 0.8% encodes stable RNAs, and 0.7% consists of noncoding repeats. Eleven percent of the genome are involved in regulation of gene expression and also other functions [9]. A circular map of the *E. coli* genome is represented in **Figure 4**.

The map is based on the K-12 MG1655 sequence data as deposited in GenBank (Accession number NC\_000913) [10]. The multiplier for the ticks is 1e-6 (1.0 represents 1,000,000). In blue, the forward genes are shown, in purple the reverse genes, tRNA genes in orange, and rRNA genes in red. The map was drawn with

**Figure 4.** *Circular map of the E. coli K-12 MG1655 strain.*

the online tool ClicO FS, available at the Internet site http://www.codoncloud. com:3000/home [11, 12].

Genomes of pathogenic *E. coli* strains are general bigger, as the pathogenic strains need several special properties, so-called virulence factors. These are encoded in the virulence-associated genes (VAGs), which are frequently clustered in DNA regions called pathogenicity islands (PAIs) [13]. Often the pathogenic strains possess also extrachromosomal DNA elements, i.e., plasmids, that can also carry additional VAGs [7]. Some examples of genomes of pathogenic strains in comparison with the K-12 MG1655 strain are given in **Table 1**.

Data in the table are based on data available in the genome database of the National Center for Biotechnology Information (Internet site: www.ncbi.nlm.nih.gov) [14].

The most famous *E. coli* plasmid is the plasmid F (**Figure 5**). It is the paradigm plasmid for plasmid-specified transfer systems, as bacterial conjugation was first identified as a function of the F plasmid. Further, this plasmid was used to develop many of the genetic techniques commonly used to dissect prokaryotic systems, and F product analysis has been central in elucidating the basic mechanisms of plasmid replication and transmission [15].

F plasmid has two functional replication regions, RepFIA and RepFIB. The RepFIA region is believed to be primarily responsible for the typical replication properties of F [16]. The secondary replication region, RepFIB, is independently functional and can perform replication in the absence of RepFIA. F plasmid has also remnants of a third replication region, RepFIC, whose function was abolished by transposition of Tn*1000* into this replication region [17]. Apart from Tn*1000* also insertion sequences IS2 and IS3 are carried on F plasmid [16]. The plasmid-specified transfer system is encoded in the *tra* region, starting with the origin of transfer (*oriT*) [15].

**7**

**Figure 5.**

*as deposited in GenBank [18].*

**3.3 The phylogenetic groups of** *E. coli*

high, 50,000–100,000 or more [20].

The *E. coli* species has an extensive genetic substructure and the methods to assess the phylogenetic relationship among *E. coli* strains evolved during the time. In the pre-molecular era, the *E. coli* diversity was studied by serotyping. Serotyping studies showed that the somatic (O) antigen, the flagellar (H) antigen, and to a lesser extent the capsular (K) antigen are useful in distinguishing *E. coli* strains [19]. The *E. coli* serotyping is complex—173 O antigens, 80 K antigens, and 56 H antigens are known—and the O, K, and H antigens can be found in nature in many of the possible combinations. The final number of *E. coli* serotypes is therefore very

*Map of the E. coli F plasmid. The map was drawn based on the complete nucleotide sequence of the F plasmid*

*Introductory Chapter: The Versatile Escherichia coli DOI: http://dx.doi.org/10.5772/intechopen.88882*

> **with infection**

Hemorrhagic diarrhea

infection

Crohn's disease

Hemolyticuremic syndrome

infection

**Chromosome size (Mbp)**

**Number of genes in the chromosome**

/ 4.64 4.566 / / /

5.5 5.329 pO157 92.721 85

5.13 5.092 / / /

4.75 4.532 pO83\_CORR 147.060 154

5.27 5.081 pG-EA11 1549 1

5.2 5.096 p1ESCUM 122.301 156

**Plasmids Plasmid**

**size (bp)**

pOSAK1 3306 3

pAA-EA11 74.217 82 pESBL-EA11 88.544 94

p2ESCUM 33.809 49

**Number of genes on the plasmid**

*E. coli* **strain Associated**

O7:K1 IAI39 Urinary tract

UMN026 Urinary tract

*Genomes of different E. coli strains.*

K-12 MG1655

O157:H7 Sakai

O83:H1 NRG 857C

O104:H4 2011C-3493 ASM29945v1

**Table 1.**

*Introductory Chapter: The Versatile Escherichia coli DOI: http://dx.doi.org/10.5772/intechopen.88882*

#### **Table 1.**

*The Universe of Escherichia coli*

com:3000/home [11, 12].

*Circular map of the E. coli K-12 MG1655 strain.*

**Figure 4.**

replication and transmission [15].

the online tool ClicO FS, available at the Internet site http://www.codoncloud.

Genomes of pathogenic *E. coli* strains are general bigger, as the pathogenic strains need several special properties, so-called virulence factors. These are encoded in the virulence-associated genes (VAGs), which are frequently clustered in DNA regions called pathogenicity islands (PAIs) [13]. Often the pathogenic strains possess also extrachromosomal DNA elements, i.e., plasmids, that can also carry additional VAGs [7]. Some examples of genomes of pathogenic strains in

Data in the table are based on data available in the genome database of the National

F plasmid has two functional replication regions, RepFIA and RepFIB. The RepFIA region is believed to be primarily responsible for the typical replication properties of F [16]. The secondary replication region, RepFIB, is independently functional and can perform replication in the absence of RepFIA. F plasmid has also remnants of a third replication region, RepFIC, whose function was abolished by transposition of Tn*1000* into this replication region [17]. Apart from Tn*1000* also insertion sequences IS2 and IS3 are carried on F plasmid [16]. The plasmid-specified transfer system is encoded in

Center for Biotechnology Information (Internet site: www.ncbi.nlm.nih.gov) [14]. The most famous *E. coli* plasmid is the plasmid F (**Figure 5**). It is the paradigm plasmid for plasmid-specified transfer systems, as bacterial conjugation was first identified as a function of the F plasmid. Further, this plasmid was used to develop many of the genetic techniques commonly used to dissect prokaryotic systems, and F product analysis has been central in elucidating the basic mechanisms of plasmid

comparison with the K-12 MG1655 strain are given in **Table 1**.

the *tra* region, starting with the origin of transfer (*oriT*) [15].

**6**

*Genomes of different E. coli strains.*

#### **Figure 5.**

*Map of the E. coli F plasmid. The map was drawn based on the complete nucleotide sequence of the F plasmid as deposited in GenBank [18].*

#### **3.3 The phylogenetic groups of** *E. coli*

The *E. coli* species has an extensive genetic substructure and the methods to assess the phylogenetic relationship among *E. coli* strains evolved during the time. In the pre-molecular era, the *E. coli* diversity was studied by serotyping. Serotyping studies showed that the somatic (O) antigen, the flagellar (H) antigen, and to a lesser extent the capsular (K) antigen are useful in distinguishing *E. coli* strains [19]. The *E. coli* serotyping is complex—173 O antigens, 80 K antigens, and 56 H antigens are known—and the O, K, and H antigens can be found in nature in many of the possible combinations. The final number of *E. coli* serotypes is therefore very high, 50,000–100,000 or more [20].

The molecular studies of *E. coli* diversity began with the measurement of variations in electrophoretic mobility of enzymes derived from different *E. coli* strains [21]. In 1980s the multi-locus enzyme electrophoresis (MLEE) became the common technique for the study of bacterial diversity. It was found that *E. coli* populations evolve in a clonal manner, with recombination playing a limited role, and it also became clear that genetically distant strains can have the same serotype and that closely related strains may have different serotypes [19]. Based on the MLEE studies of 38 enzyme loci, four major phylogenetic groups among *E. coli* were found: A, B1, B2, and D [22]. Clermont et al. [23] established a method of rapid and simple determination of the *E. coli* phylogenetic groups by a triplex PCR. This genotyping method is based on the amplification of a 279 bp fragment of the *chuA* gene; a 211 bp fragment of the *yjaA* gene; and a 152 bp fragment of TSPE4.C2, a noncoding region of the genome. The presence or absence of combinations of these three amplicons is used to assign the *E. coli* to the phylogenetic groups: A, B1, B2, or D (**Figure 6**).

However, subsequently, on the basis of multi-locus sequence typing and complete genome data, additional *E. coli* phylogenetic groups were recognized [24, 25]. The number of defined phylogenetic groups thus rose to eight (A, B1, B2, C, D, E, F that belongs to *E. coli* sensu stricto, and the eighth—the *Escherichia* cryptic clade I). Clermont et al. [26] thus revised their method to encompass the newly described phylogenetic groups. To enable identification of the F phylogenetic group, the new extended PCR phylotyping method employs an additional gene target, *arpA*, which serves also as an internal control for DNA quality. Thus, the revised PCR method is based on a quadruplex PCR, and if required, additional single PCR reactions are employed to distinguish between E and clade I, A or C, and D or E phylo-group [26] (**Figure 7**).

Two collections of human fecal isolates were screened using the quadruplex phylo-group assignment method demonstrating that 12.8% of *E. coli* isolates belonged to the newly described phylo-groups C, E, F, and clade I and that strains assigned to phylo-groups A and D by the triplex method are worth to be retested by the quadruplex method, as it is likely that they are going to be reclassified [26]. Logue et al. [27] performed a comparative analysis of phylogenetic assignment of human and avian extraintestinal pathogenic (ExPEC) and fecal commensal *E. coli* (FEC) strains and showed that a total 13.05% of studied human *E. coli* strains and 40.49% of avian *E. coli* strains had to be

**Figure 6.**

*Dichotomous decision tree to determine the phylogenetic group by the Clermont triplex PCR method [23].*

**9**

strains.

**Figure 7.**

**3.4 The commensal** *E. coli*

also designated as mutualistic *E. coli*.

**3.5 The pathogenic** *E. coli*

*Introductory Chapter: The Versatile Escherichia coli DOI: http://dx.doi.org/10.5772/intechopen.88882*

reclassified. Another study using human *E. coli* strains isolated from skin and soft-tissue infections and fecal *E. coli* strains from healthy humans and also avian and brown bear fecal strains revealed that 27.60% of human, 23.33% of avian, and 70.93% of brown bear strains had to be reclassified. Moreover, a high number (12.22%) of reclassifications from the previous phylo-groups to the non-typeable (NT) group were observed among the avian fecal strains of this study. Further, a survey performed on other published data by Starčič Erjavec et al. [28] showed that also a number of other studies report occurrence of NT strains by the quadruplex method, for example, a study including 140 uropathogenic *E. coli* strains from Iran reported 27.14% of NT strains [29]. These data emphasizes that there is a need to search for more *E. coli* strains from novel environments (new hosts in not yet explored geographic regions) and to revise the PCR phylotyping method again in order to type these NT

*Dichotomous decision tree to determine the phylogenetic group by the Clermont quadruplex PCR method [26].*

As *E. coli* is a facultative anaerobe, and among the first gut colonizers, these bacteria help to establish the anaerobic environment of the gut that enables the further colonization of the gut by anaerobic bacteria [30]. After the *E. coli* colonization, usually the host and *E. coli* coexist in mutual benefit for decades [7]. *E. coli* gets "food and shelter," and the host benefits due to the *E. coli* vitamin K production and the so-called colonization resistance. Colonization resistance is the phenomenon of protection against colonization by pathogenic bacteria, including pathogenic *E. coli* [31]. The niche of the commensal *E. coli* is the mucous layer of the colon [7]. On average five different commensal *E. coli* strains colonize a human host at any given time [32]. As host and the *E. coli* profits from their association, these *E. coli* could be

*E. coli* is also a medically important species, as it is involved in many different types of infections. Two major groups of pathogenic *E. coli* exists: the intestinal

*Introductory Chapter: The Versatile Escherichia coli DOI: http://dx.doi.org/10.5772/intechopen.88882*

*The Universe of Escherichia coli*

or C, and D or E phylo-group [26] (**Figure 7**).

The molecular studies of *E. coli* diversity began with the measurement of variations in electrophoretic mobility of enzymes derived from different *E. coli* strains [21]. In 1980s the multi-locus enzyme electrophoresis (MLEE) became the common technique for the study of bacterial diversity. It was found that *E. coli* populations evolve in a clonal manner, with recombination playing a limited role, and it also became clear that genetically distant strains can have the same serotype and that closely related strains may have different serotypes [19]. Based on the MLEE studies of 38 enzyme loci, four major phylogenetic groups among *E. coli* were found: A, B1, B2, and D [22]. Clermont et al. [23] established a method of rapid and simple determination of the *E. coli* phylogenetic groups by a triplex PCR. This genotyping method is based on the amplification of a 279 bp fragment of the *chuA* gene; a 211 bp fragment of the *yjaA* gene; and a 152 bp fragment of TSPE4.C2, a noncoding region of the genome. The presence or absence of combinations of these three amplicons is used to assign the *E. coli* to the phylogenetic groups: A, B1, B2, or D (**Figure 6**). However, subsequently, on the basis of multi-locus sequence typing and complete genome data, additional *E. coli* phylogenetic groups were recognized [24, 25]. The number of defined phylogenetic groups thus rose to eight (A, B1, B2, C, D, E, F that belongs to *E. coli* sensu stricto, and the eighth—the *Escherichia* cryptic clade I). Clermont et al. [26] thus revised their method to encompass the newly described phylogenetic groups. To enable identification of the F phylogenetic group, the new extended PCR phylotyping method employs an additional gene target, *arpA*, which serves also as an internal control for DNA quality. Thus, the revised PCR method is based on a quadruplex PCR, and if required, additional single PCR reactions are employed to distinguish between E and clade I, A

Two collections of human fecal isolates were screened using the quadruplex phylo-group assignment method demonstrating that 12.8% of *E. coli* isolates belonged to the newly described phylo-groups C, E, F, and clade I and that strains assigned to phylo-groups A and D by the triplex method are worth to be retested by the quadruplex method, as it is likely that they are going to be reclassified [26]. Logue et al. [27] performed a comparative analysis of phylogenetic assignment of human and avian extraintestinal pathogenic (ExPEC) and fecal commensal *E. coli* (FEC) strains and showed that a total 13.05% of studied human *E. coli* strains and 40.49% of avian *E. coli* strains had to be

*Dichotomous decision tree to determine the phylogenetic group by the Clermont triplex PCR method [23].*

**8**

**Figure 6.**

**Figure 7.** *Dichotomous decision tree to determine the phylogenetic group by the Clermont quadruplex PCR method [26].*

reclassified. Another study using human *E. coli* strains isolated from skin and soft-tissue infections and fecal *E. coli* strains from healthy humans and also avian and brown bear fecal strains revealed that 27.60% of human, 23.33% of avian, and 70.93% of brown bear strains had to be reclassified. Moreover, a high number (12.22%) of reclassifications from the previous phylo-groups to the non-typeable (NT) group were observed among the avian fecal strains of this study. Further, a survey performed on other published data by Starčič Erjavec et al. [28] showed that also a number of other studies report occurrence of NT strains by the quadruplex method, for example, a study including 140 uropathogenic *E. coli* strains from Iran reported 27.14% of NT strains [29]. These data emphasizes that there is a need to search for more *E. coli* strains from novel environments (new hosts in not yet explored geographic regions) and to revise the PCR phylotyping method again in order to type these NT strains.

#### **3.4 The commensal** *E. coli*

As *E. coli* is a facultative anaerobe, and among the first gut colonizers, these bacteria help to establish the anaerobic environment of the gut that enables the further colonization of the gut by anaerobic bacteria [30]. After the *E. coli* colonization, usually the host and *E. coli* coexist in mutual benefit for decades [7]. *E. coli* gets "food and shelter," and the host benefits due to the *E. coli* vitamin K production and the so-called colonization resistance. Colonization resistance is the phenomenon of protection against colonization by pathogenic bacteria, including pathogenic *E. coli* [31]. The niche of the commensal *E. coli* is the mucous layer of the colon [7]. On average five different commensal *E. coli* strains colonize a human host at any given time [32]. As host and the *E. coli* profits from their association, these *E. coli* could be also designated as mutualistic *E. coli*.

#### **3.5 The pathogenic** *E. coli*

*E. coli* is also a medically important species, as it is involved in many different types of infections. Two major groups of pathogenic *E. coli* exists: the intestinal

#### *The Universe of Escherichia coli*

pathogenic *E. coli* (IPEC), associated with infections of the gastrointestinal tract, and the extraintestinal pathogenic *E. coli* (ExPEC), associated with infections of extraintestinal anatomic sites [7]. The medical diversity of this species is nicely exhibited by its classification of pathogenic *E. coli* (**Figure 8**), the so-called *E. coli* pathotypes.

The versatility of pathogenic *E. coli* strains depends on their genetic makeup, on the presence of so-called virulence genes, and possession of such genes distinguishes pathogenic from nonpathogenic bacteria [34]. Virulence factors help bacteria to (1) invade the host, (2) cause disease, and (3) evade host defenses [35].


**Cogeneration Power-Desalting Plants Using Gas Turbine Combined Cycle**

M.A. Darwish, H.K. Abdulrahim, A.A. Mabrouk and A.S. Hassan

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/60209

#### **Abstract**

The gas-steam turbine combined cycle (GTCC) is the preferred power plant type because of its high efficiency and its use of cheap and clean natural gas as fuel. It is also the preferred type in the Arab Gulf countries where it is used as cogeneration power-desalting plant (CPDP). In this chapter, descriptions and analysis of the GTCC components are presented, namely, the gas turbine cycle (compressor, combustor, gas turbine), heat recovery steam generator, and steam turbine. Combinations of the GTCC with thermally driven desalination units to present CPDP are presented. A parametric study to show the effect of using GTCC on several operating parameters on the CPDP is also presented, as well as cost allocation methods of fuel between the two product utilities (electric power and desalted seawater are also presented).

**Keywords:** multi stage flash, multi effect with thermal vapor compression, reverse osmosis, steam power plants, gas turbines, combined cycle, cost allocation, energy and exergy analyses

### **1. Introduction**

The efficiency of power plant (PP) using gas turbine (GT) combined cycle (GTCC) is higher than that of steam cycle PP prevailed as baseload-type plant before 2000, and the GT power cycle that was used as peak load and starting units in these steam PPs. The efficiency of the steam turbine (ST) plants is in the range of 35–40 %, the GT is in the range of 30–36 %, and

© 2015 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.

GTCC is in the range of 45–58 % (Figure 1). This is the main reason for the GTCC to become the preferred-type PP in the Gulf Cooperation Countries (GCC) and worldwide, besides using clean and cheap natural gas (NG) as a fuel. Increasing the PP efficiency reduces the emissions of greenhouse gases (GHG), sulfur dioxide, and nitrogen oxide. The GTCC (Figure 2a) includes an upper GT cycle (i.e., compressor, combustion chamber (cc), gas turbine) and bottom steam cycle (i.e., heat recovery steam generator (HRSG), steam turbine (ST), and condenser). The GT cycle produces almost 2/3 of the GTCC electric power (EP) output, with mainly NG used as fuel supplied to the cc. Hot gases exhausted from the GT (typically at 475–600 ο C) are directed to HRSG to produce steam. This steam, when at high-enough temperature and pressure, is directed to ST to produce more work without adding more fuel. The ST cycle produces about 1/3 of the GTCC power output. Processed heat (in the form of steam) produced from the HRSG or extracted (or discharged) from the ST can be used to operate desalting plant (DP), district heating absorption cooling, and/or other processes.

**Figure 1.** SGT6-5000F CC efficiency evolution [2]

Most PPs in the GCC are cogeneration power-desalting plants producing both desalted seawater (DW) and EP in single plants called CPDP. The desalting units are supplied with its needed low-pressure (LP) steam by extracting (or discharging) steam from the ST of the GTCC or directly from the HRSG when the ST is not operated or does not exist. The ST used in the GTCC can be extraction-condensing steam turbine (ECST) or back-pressure steam turbine (BPST) discharging all of its steam to the DP. Examples of recently installed CPDP using GTCC are Shuaiba North in Kuwait, (Figure 2b), Jebel Ali in the UAE, and Ras Girtas and Mesaieed in Qatar.

In Kuwait, all power plants were of steam type before 2003 and were combined with mainly multistage flash (MSF) desalting plants (DP) up to 2003 to form CPDP; see Table 1. The use of ST for power production in Kuwait followed the 1980s general world trend of using ST in the PP, when the share of GTCC plants was very limited. In the 1990s, the share of GTCC increased very rapidly in the world due to extensive improvements in the GTs. These improvements in GT resulted in reliable GTCC technology and low capital cost of the GTCC plants compared to the ST cycle of the same capacity. NG availability at low cost in many parts of the world and Cogeneration Power-Desalting Plants Using Gas Turbine Combined Cycle http://dx.doi.org/10.5772/60209 129

GTCC is in the range of 45–58 % (Figure 1). This is the main reason for the GTCC to become the preferred-type PP in the Gulf Cooperation Countries (GCC) and worldwide, besides using clean and cheap natural gas (NG) as a fuel. Increasing the PP efficiency reduces the emissions of greenhouse gases (GHG), sulfur dioxide, and nitrogen oxide. The GTCC (Figure 2a) includes an upper GT cycle (i.e., compressor, combustion chamber (cc), gas turbine) and bottom steam cycle (i.e., heat recovery steam generator (HRSG), steam turbine (ST), and condenser). The GT cycle produces almost 2/3 of the GTCC electric power (EP) output, with mainly NG used as

to HRSG to produce steam. This steam, when at high-enough temperature and pressure, is directed to ST to produce more work without adding more fuel. The ST cycle produces about 1/3 of the GTCC power output. Processed heat (in the form of steam) produced from the HRSG or extracted (or discharged) from the ST can be used to operate desalting plant (DP), district

Most PPs in the GCC are cogeneration power-desalting plants producing both desalted seawater (DW) and EP in single plants called CPDP. The desalting units are supplied with its needed low-pressure (LP) steam by extracting (or discharging) steam from the ST of the GTCC or directly from the HRSG when the ST is not operated or does not exist. The ST used in the GTCC can be extraction-condensing steam turbine (ECST) or back-pressure steam turbine (BPST) discharging all of its steam to the DP. Examples of recently installed CPDP using GTCC are Shuaiba North in Kuwait, (Figure 2b), Jebel Ali in the UAE, and Ras Girtas and Mesaieed

In Kuwait, all power plants were of steam type before 2003 and were combined with mainly multistage flash (MSF) desalting plants (DP) up to 2003 to form CPDP; see Table 1. The use of ST for power production in Kuwait followed the 1980s general world trend of using ST in the PP, when the share of GTCC plants was very limited. In the 1990s, the share of GTCC increased very rapidly in the world due to extensive improvements in the GTs. These improvements in GT resulted in reliable GTCC technology and low capital cost of the GTCC plants compared to the ST cycle of the same capacity. NG availability at low cost in many parts of the world and

C) are directed

fuel supplied to the cc. Hot gases exhausted from the GT (typically at 475–600 ο

heating absorption cooling, and/or other processes.

**Figure 1.** SGT6-5000F CC efficiency evolution [2]

in Qatar.

128 Desalination Updates

**Figure 2.** a: Gas turbine combined with steam turbine forming GTCC [1] b: Schematic diagram of Shuaiba North (GTCC) combined with MSF desalination plant

the high efficiency of the GTCC (and thus the use of less fuel with less impact on the environ‐ ment) promoted the share of the GTCC all over the world. Today, the GTCC-type PP becomes the preferred choice of PPs in most areas in the world, particularly in the GCC as shown in Table 2. Moreover, the GTCC equipment costs are less than that of the conventional ST plants.

**Table 1.** Cogeneration steam power-desalination plants in Kuwait up to 2003 [1]

**Table 2.** Recent combined cycle plants with MSF units in the United Arab Emirates and Saudi Arabia [1]

This article presents description of GTCC power plant units, detailing the GT, HRSG, ST, and their combining arrangements with DP to form CPDP. Methods of allocating the fuel supplied to the CPDP using GTCC between the EP and DW are presented.


**Acknowledgements**

Thanks to the Santiago de Cali University, to the COMBA I+D group, for the sponsorship and support for the development of this research work.

*Management Methods of Energy Consumption Parameters Using IoT and Big Data DOI: http://dx.doi.org/10.5772/intechopen.105522*


**Appendix B**

Details about sieving non-spherical objects and the sieving procedure conducted are described here. Due to the high aspect ratio between the length and width and/or thickness of the chipped material, the use of sieves is not as straightforward as with more spherical objects. The amount of material passing through the sieve depends on the amount of material placed on the sieve, the movement produced for sieving, and the sieving time. If too much material is placed on the sieve, particles are more likely to be arranged in a position perpendicular to the sieve holes (vertically). The horizontal sieving technique was chosen to limit the vertical repositioning of the particles after being positioned on a sieve. The speed of the circular sieve movement can also cause the particles to reposition vertically. Therefore, these three variables were kept constant throughout the sieving of the chipped straw.

The sieving process for the 5.7 mm sieve consisted of placing 140 g of chipped material on the 5.7 mm sieve and making 10 horizontal circles with the sieve for 8 s in a clockwise direction, then in an anti-clockwise direction. The sieving process for the 1.5 mm sieve consisted of placing 70 g of chipped material on the 1.5 mm sieve and making 5 horizontal circles with the sieve for 4 s in a clockwise direction, then in an anti-clockwise direction.

## **Appendix C**

The details of the procedure performed to quantify the particle sizes of both mixture are presented here. First, particles were positioned on a light table while making sure that they did not touch each other. If particles were touching each other, the algorithm would recognize them as one, and resulting dimensions would be false. A picture of these particles was taken from a top view with a Sony alpha 7R II camera (Sony, New York City, NY, USA) mounted on a tripod. The following settings were used: f/4, 1/100 s, ISO-100 at a focal length of 35 mm. The 35 mm focal length was used to reduce lens distortion. The picture was then opened in Adobe Lightroom (version 6.10.1, AdobeTM, San Jose, CA, USA) to crop, increase contrast, and correct the lens distortion. The adjusted pictures were then imported into a Python script (version 3.7, Python Software Foundation, Wilmington, DE, USA). The script turned the image into a binary image (e.g., only composed of black or white pixels), labeled each individual item, and calculated the number of objects and the area, perimeter, eccentricity, major axis length, and minor axis length of each item. A ruler integrated in the light table was used to scale the image by converting the number of pixels from the picture to mm.

### **Appendix D**

The pasteurization process can be divided into the following steps: first, the substrate mixture (S or L) is placed in a large steamer with a rotating arm in its center. Then, the required amount of water is added to the mixture based on the necessary percentages from the inoculation recipe (detailed in Section 2.3). The steamer is then closed and both mixing and steaming are started. The steamer is kept on for one hour at a temperature of 64–65 ◦C to allow proper pasteurization. A thermal blanket is placed around the mixer to retain the heat. The mixture is then allowed to cool for one hour until it reaches a temperature of 27 ◦C. To speed up the cooling, the mixer is kept on and the fan of the steamer blows filtered outdoor air through the mixture. To enhance the pasteurization process, water is introduced before pasteurizing the substrate. However, the pasteurization process also brings moisture in. To quantify the quantity of water added to the mixture during the pasteurization process, the team ran the steamer without any substrate. The steamer produced approximatively 5.90 L of water, which represented 13.40% of the water in our inoculation recipe.

### **Appendix E**

The inoculation procedure of both batches and summary of the quantity of materials grown are described here. Mixture L of the first batch was inoculated as follows: first, 9303.3 g of sterilized dry substrate was placed inside a sterilized drum mixer. With the drum mixer on (i.e., rotating), 28 L of distilled water was slowly poured inside the mixer. The mixer was left running to mix the substrate and water for 10 min. Then, 4134.8 g of *Pleurotus ostreatus* grain spawn was added. The whole mixture was mixed for an additional 30 min. The molds were sterilized with 70% isopropyl alcohol. After 30 min of mixing, the mixture was placed and compacted into the sterilized molds. The mixer was kept running while the team filled the molds to prevent the mixture from sitting still for too long. An acrylic disk was used for pushing by hand as hard as possible to compact the mixture multiple times during the filling process. For the 17 cm tall PVC tubes, the mixture was compacted twice: when the mixture filled half of the tube height and when it filled the entire height. For the 34 cm tall PVC tubes, the mixture was compacted four times (i.e., at each quarter of the height). Once the molds were filled, specimens for compression testing were covered with a layer of non-woven housewrap (Everbilt, Home Depot, USA) to maintain constant humidity, reduce the exposure to contaminants, and limit mycelium growth on the outer surfaces. In mycelium materials, the surfaces exposed to ambient air display increased mycelial growth. This phenomenon impacts mechanical behavior as shown in a study about jacketing the materials [44]. The bias emerging from increased mycelium growth on external surface was reduced in our study by compacting mixtures in the molds and growing all specimens in PVC tubes with top and bottom surfaces covered with housewrap. Specimens for bending testing were placed inside a ridge-like tent. The ridge-like tent was made of non-woven housewrap and clear plastic, to ensure mycelium growth was visible throughout the growth period. All covered molds were finally placed inside a sterilized large tent in order to lower the risks of contamination. An opaque tarp covered the large tents containing the specimens during the growth process to block sunlight, which is a stimulus for the formation of fruiting bodies. Filtered air flowed into this tent throughout the mycelial growth period. The same process was performed for mixture S with the following quantities: 11,841.3 g of sterilized dry substrate, 35.5 L of distilled water, and 5262.8 g of *Pleurotus ostreatus* grain spawn. The leftover inoculated mixtures, S and L, filled four additional rectangular molds each. The filled molds were then sealed with a layer of non-woven housewrap.

For the second batch, water was added before the pasteurization process and the mycelium spawn after it. Once the mixture had cooled to 27 ◦C, the mycelium spawn was added. After 5 min of mixing, the inoculated mixture was placed inside opaque trash bags to be transported to the growth facility (redhouse studio's warehouse in Cleveland, OH, USA). The temperature of the inoculated mixture should remain constant to avoid early growth and contaminants. Therefore, bags were only half filled with an average of 13.4 kg of inoculated mixture. These bags were then spread on a grid to reduce the heat produced by this biomass. Due to the time needed to fill all the molds, mixture S was placed in the molds on the day following inoculation, whereas mixture L was placed two days after inoculation. After being sterilized with 70% ethanol, the molds were filled with the inoculated mixture and pressed to achieve the desired heights akin to the previous batch. Finally, the filled molds were weighed and placed in their respective growth environments. The growth environments used for the first batch were reused for the second batch. In the first batch, the closed PVC tubes were set on a planar surface to maintain a flat surface on the specimens' bottom sides. However, this configuration did not let the specimens fully breathe during the growth period resulting in high humidity of the lower parts of the specimens and the presence of higher rates of contamination. Therefore, for the second

batch, the filled PVC molds were placed on a metal grid to let them breathe. The leftover inoculated mixtures, S and L, filled eight additional rectangular molds each. Similar to the first batch, a layer of non-woven housewrap was used to cover these filled molds.

A total of 120 specimens were grown to evaluate the effects of the following variables on the compressive properties of mycelium-based composites: fungal species (*Pleurotus ostreatus* and *Coprinus comatus*), substrate particle sizes (with or without micro-particles), and post-growth treatments (dried, baked, compacted then dried, and compacted then baked). A total of 40 specimens were grown for the first batch with *Pleurotus ostreatus* to achieve a sample size of five. Due to increased availability of materials, space, time, and levels of contaminations observed in the first batch, the sample size was increased to 10 (80 specimens total) for the second batch grown with *Coprinus comatus*. For bending testing, the effects of the same variables were evaluated with a total of 148 specimens. The sample sizes used were 6 for the first batch (48 specimens) and 12 or 15 for the second batch (100 specimens), depending on the number of molds and material available.


*4.8. Neuroprotective Activity*

Supplementation with *M. koenigii* leaf extracts has been reported in the management of a wide spectrum of neurodegenerative diseases, like AD, PD, and others [30,33–35,41]. *M. koenigii* promotes neuroprotective potential against orofacial dyskinesia induced by resperine. Additionally, it stabilizes the levels of protective antioxidant enzymes like SOD, catalase (CAT), and GSH, and inhibits LPO in the forebrain regions of reserpine-treated animals. Furthermore, it has been shown to significantly inhibit reserpine-induced abnormalities in behavior. Similarly, treatment with *M. koenigii* significantly restored the levels of protective antioxidant enzymes (that is, SOD, CAT, and GSH) and inhibited LPO in the forebrain region when compared with reserpine, and it also inhibited catalepsy induced by haloperidol [36]. Isolongifolene (ILF), a tricyclic sesquiterpene of *M. koenigii*, has been reported to render neuroprotective effects against rotenone-induced mitochondrial dysfunction, oxidative stress, and apoptosis in a cellular model. Cytotoxicity, oxidative stress, and mitochondrial dysfunction were also attenuated by ILF in SH-SY5Y cells, which down-regulated Bax and caspases-3, -6, -8, and -9 expression, and up-regulated Bcl-2 expression. IFL was proved to regulate p-P13K, p-AKT, and p-GSK-3 beta expressions [87]. Preclinical studies have reported that *M. koenigii* leaves could enhance memory in rats [119]. The possible neuroprotective potential of amethanolic extract of *M. koenigii* leaves was exhibited in a two-vessel occlusion (2VO) rat model of partial global cerebral ischaemia. The Morris water maze test was implemented to assess the rats' cognitive function postoperatively. Brain samples were histopathologically examined for viable neurons within the CA1 hippocampal region. Test findings showed that *M. koenigii* leaves positively improved memory and learning impairments. *M. koenigii* leaf extracts modestly improved memory in rats with chronic partial global cerebral ischemia [120]. The various activities of *M. koenigii* against neurotoxicity are shown in Figure 3.

**Figure 3.** Neuroprotective effect in in vitro and in vivo studies produced by bioactive compounds from *M. koenigii.* PI3: phosphatidylinositol 3 kinase; GSK3β: Glycogen synthase kinase 3 beta; Ach: Acetylcholine; Bax: Bcl2-Associated X protein.


**4. DEA to gaseous DNA subunits and radiosensitizers**

## **4.1. DNA bases**

absolute cross section for Cl*‾*production at the peak values increases with decreasing thickness of the Kr film. When CH3Cl*‾* is formed too close to the metal substrate, the additional electron

**Figure 2.** CH3Cl*‾* formation and dissociation by electrons of 0–2.5 eV incident on submonolayer amounts of CH3Cl physisorbed on a multilayer film of Kr. (a) Variation of the charging coefficient of the film As due to CH3Cl*‾* dissocia‐ tion. (b) Variation with film thickness of: (■) the amplitude of the maximum in the charging cross section (*μ*); (‐·‐·) the amplitude of the maximum in *μ* calculated with the *R*‐matrix method [37]; (•) variation of the energy of maximum in *μ*

In the condensed phase, TMAs differ from their gas‐phase counterparts, in the following ways: (1) the electron energies required for their formation are usually lower by 0.5–1.5 eV, dependent

and As; and (‐‐‐) a parametric fit of this maximum using the image charge model [38].

transfers to the metal, and *μ* sharply decreases.

186 Radiation Effects in Materials

A large number of DEA studies have been performed on gas‐phase DNA bases and their derivatives over the last two decades [2, 39]. Briefly, DEA is the resonant process that involves the LEE capture by a molecule (AB) to produce gaseous TMAs ((AB)‾), described in Section 2, which then dissociate into an anion (A‾) and a neutral radical or radicals (B•), according to the following reaction:

$$\text{e}^- + AB \leftrightarrow \left(AB\right)^- \rightarrow A^- + B^\* \tag{5}$$

In general, the low‐energy resonances in nucleobases are present either at subexcitation (< 3 eV) energies or in the energy range 5–12 eV [39]. The yield function for the DEA processes for thymine resulting in multiple fragment formation is shown in **Figure 3**. To analyze the formation of the negative ions, yield functions were usually recorded by scanning the incident electron energy, while potential voltages applied to the quadrupole mass spectrometer were set for a given ion mass. The ion yields were detected by a channeltorn and plotted as a function of the incident electron energy.

The high‐energy resonances lead to transient anion fragmentation via opening of the ring structure, while the low‐energy resonances are primarily due to loss of one or two neutral hydrogen, which maintains the ring structure.

The DEA yield functions for nucleobases and their related compounds show a remarkable feature that can be recognized as a common phenomenon, that is, site selectivity [40–42]. By tuning the energy of the incoming electron, it is possible to control the location of the bond cleavage. That is, a specific chemical bond in a molecule can be targeted by electrons followed by fragmentation. As an illustration of this site selectivity in nucleobases, DEA to thymine with deuterated and methylated substitutions is described. This phenomenon was observed for other nucleobases and their derivatives, for example, adenine [43] and hypoxanthine [44].

**Figure 3.** (a) Total ion yield as a function of electron energy for DEA process of thymine. (b) Formation of dehydrogen‐ ated anions from thymine (black curve), methylated thymine at N3 site (red curve), methylated thymine at N1 site (blue curve), and thymidine (gray area) [45]. Molecular structure of thymine with numbering and atom labeling.

At subexcitation energies, DEA leads to thymine dehydrogenation by loss of a neutral hydrogen atom [40, 42]. This reaction can be expressed as follows:

$$e^- + T \to T^- \to T^-\_{-H} + H^\* \tag{6}$$

where T− is the TMA of thymine (T) and T−H − is the closed‐shell anion formed by the ejection of a neutral hydrogen radical <*i* >H• < / *i* >. This dehydrogenation process depends on the site from which the H atom is removed. Experimental studies with partially deuterated thymine, in which the deuterium is at either nitrogen or carbon sites, showed that hydrogen loss occurs exclusively from the N sites. H loss from the C sites is thermodynamically accessible within this energy range, but has not been observed experimentally. Moreover, in employing methylated thymine and uracil, it has been shown that by adjusting the electron energy, the loss of H can be made even site‐selective with respect to the N1 and N3 positions. Although 1 eV electrons induce H loss at the N1 position (N1‐H), the process can be switched at 1.8 eV to N3‐H (**Figure 3b**). These results have significant consequences for the molecular mechanism of DNA strand breaks induced by LEEs. Within DNA, the N1 position of thymine is coupled with the sugar moiety and thus forms thymidine, which is one of the nucleosides. Because the shapes of the signals from thymine and the more complex thymidine resemble each other, it can be concluded that H abstraction in thymidine predominantly occurs at the thymine moiety and, more precisely, at the N3 position (**Figure 3b**) [45].

In addition to the detection of anions and the energies at which they are formed, much effort has been expended to matching particular types of DEA process to specific resonant peaks observed in DEA ion yields. In the case of the most abundant anion formed for all nucleobases, it has been proposed that these resonant peaks can be assigned to vibrational Feshbach resonances (VFRs) [46, 47]. VFRs usually occur at low energies, when vibrational levels of the transient anion lie below the corresponding vibrational states of the neutral, and are more expected in greatly polarized molecules with very large dipole moment, which leads to a long‐ range attractive interaction. They may serve as a gateway for dissociation at low energies if they are coupled with a dissociative valence state. This can be the case for the formation of dehydrogenated ions from nucleobases, where resonances arise from coupling between the dipole bound state and the transient anion state associated with the occupation of the lowest *σ*\* orbital. Recently, the nucleobase fragmentation of N–H bonds induced by LEEs was studied by employing the CASPT2//CASSCF computational approach [48]. These calculations showed that the two lowest lying π\* states can be determined at energies below 1.0 eV and above 2.0 eV for pyrimidines, whereas for purines, this energy gap between the two anionic states was less pronounced. These calculations also suggested the possibility of coexistence of dipole‐ bound and valence‐bound processes in the low‐electron energy range.

Further to the observations of site selectivity in DEA processes leading to single‐bond cleavage within a nucleobase, site selectivity also occurred in multiple‐bond cleavage. As in the cases of both dehydrogenation of nucleobases and its complementary channels, which resulted in the Hˉ formation, site selectivity was demonstrated when multiple‐bond cleavage was involved, for example, for the formation of NCO‾ from thymine and its derivatives [49]. This anionic fragment was formed in a sequential decay reaction, in which the dehydrogenated anionic nucleobase acts as an intermediate product. In this case, the remarkable resonances, which were observed for dehydrogenation and for H reaction channels in nucleobases, were preserved for the subsequent decay reaction, leading to the formation of NCO‾ as the final product.

In general, the total cross sections for DEA to nucleobases exhibited comparable magnitudes in the energy range for TMA formation [50]. However, these cross sections were up to 10 times smaller than those for the formation of single‐strand breaks, while the cross sections for sugar and phosphate group analogs (see Section 4.2) were even smaller in magnitude.


3.2.1. Catalyst Preparation

The transition metal-modified TS-1 was prepared by an ultrasonic impregnation method [20]. A total of 4.00 g TS-1 was dispersed in 20 mL of deionized water, and sodium carbonate (Na2CO3:Mn+ = 2:1) was added as precipitator. Under vigorous stirring, the corresponding aqueous solution of metal nitrate with certain quality was slowly dripped. The mixture was sonicated for 1 h and stirred

vigorously for 3 h. Then the mixture was filtered and the solid was dried at 120 ◦C overnight and calcined at 550 ◦C for 6 h to obtain M-TS-1 (M is Fe, Co, Ni, Cu, Ce). The loading X is defined as m (metal element)/m (TS-1), and the range of X is 1–5 wt %.


**B. Dielectric and magnetodielectric (MD) effect**

function *χ*(*k*), the background absorption features which were superimposed on the EXAFS oscillations were removed from the spectrum using spline fit to both the pre-edge and the post-

**A. Structural studies through transmission electron microscopy (TEM) and X-ray diffraction (XRD):** Typical data are shown for Er2O3:SiO2 NPs-glass composite system having 0.5 mol% dopant Er2O3 concentration calcined at different temperatures, namely, 700, 800, 900, and 1200°C (henceforth referred as Er05-7, Er05-8, Er05-9 and Er05-12, respectively) [20]. Here, we discuss the TEM image of the powder specimen of typical Er05-8 (Figure 2(a)), showing nearly spherical NPs of Er2O3 embedded in the glass matrix in the range of 3–6 nm. The particle size distributions histogram (upper inset of Figure 2(a)) of the sample is calculated by counting onto the the micrograph at least 100 particles from Figure 2. The high-resolution TEM (HRTEM) image (lower inset of Figure 2(a)) of the respective sample also shows lattice fringes with interplanar spacing (3.04 Å). The selected area electron diffraction (SAED) pattern (Figure 2(b)) also shows spotted ring patterns, developing the regions of localized crystallinity.

Colossal dielectric and MD response of RE2O3 nanoparticles in SiO2 glass matrix

 TEM image of the powder specimen of typical Er05-8 (Figure 2(a)), showing nearly spherical NPs of Er2O3 2 embedded in the glass matrix in the range of 3–6 nm. The particle size distributions histogram (upper inset of Figure 2(a)) of the sample is calculated by counting onto the the micrograph at least 100 particles from Figure 2. The high-resolution TEM (HRTEM) image (lower inset of Figure 2(a)) of the respective sample also shows lattice fringes with interplanar spacing (3.04 Å). The selected area electron diffraction (SAED) pattern (Figure 2(b)) also shows spotted ring patterns, developing

34 Figure 2. (Color online) (a) TEM image of Er05-8, upper inset: the particle size distribution histogram 35 and lower inset: the HRTEM image, (b) electron diffraction and (c) XRD patterns of all the Er05-7,

**Figure 2.** (Color online) (a) TEM image of Er05-8, upper inset: the particle size distribution histogram and lower inset: the HRTEM image, (b) electron diffraction and (c) XRD patterns of all the Er05-7, Er05-8 and Er05-12 samples.

**(622)**

**(222)**

**(400) (440)**  Intensity (arb. unit)

**(c)**

(211)

(222)

**Counts**

The XRD patterns of the Er2O3 oxide NPs doped SiO2 matrix calcined at 1200o 37 C (Er05-12) show crystalline nature with quite large Er2O3 38 NPs. It exhibits clearly in Figure 2(c) the most intense

40 corresponding the unit cell parameter *a* = 10.54 Å (space group: *Ia3*(206)). The sizes of Er-oxide NPs 41 in Er05-12 are also estimated (> 40 nm) by applying the well-known Scherrer's equation from the 42 integral breadths of the XRD lines. XRD patterns cannot be well resolved from feeble broad peaks 43 due to their amorphous-like character of Er05-7 and Er05-8 samples. However, it is significantly mentioned here that the sizes of Er2O3 44 NPs grow larger for samples calcined at higher temperatures. In the SiO2 glass matrix, low concentrations of Er3+ 45 ions are bound to non-bridging oxygen atoms with quite low solubility [21]. Consequently, at a higher Er2O3 concentration with SiO2 46 (1:2), the formation of an Er2Si2O7 mixture with Er2O3 may occur at 1200o 47 C [22]. However, at a higher

C and above), there is a possibility of the formation of Er2Si2O7 48 mixture with crystalline Er2O3 49 even with very low concentration (0.5 mol %) of dopant ions. Herein, the

20 40 60

(440)

2

10 20 30 40 50 60

(400)

(3) (2) (1)

> 2(degree)

Er05-8

(622)

**2 nm**

(400)(222)

**3.04Å**

**123456789**

**Grain size (nm)**

~ 29.30° (222)

characteristic line of single phase Er2O3 39 (JCPDF Card No. 43-1007) at 2

**(a)**

**(b)**

5

edge regions.

**4. Results and discussion**

180 Ferroelectric Materials – Synthesis and Characterization

7 the regions of localized crystallinity.

36 Er05-8 and Er05-12 samples.

calcined temperature (~1200o