*3.2. Photocatalytic Disinfection of Target Pathogens*

Figure 3a,b show the photocatalytic disinfection achieved against the target pathogens at different catalyst concentrations. In Figure 3c,d bacterial disinfection is represented in its corresponding log reduction profile and the disinfection pattern is validated through comparison of the obtained profile with the standardized Chick-Watson model [11,20,21]. Figure 3a,b suggest that amongst the concentrations tested, 2 mg/L and 3 mg/L resulted in complete disinfection (6 log reductions) of *E. coli* and *S. aureus*, respectively, in 60 min and 90 min, respectively. It is observed that sunlight alone is not effective for the complete disinfection of the targeted pathogens as only 3 and 2.5 log reductions could be observed for *E. coli* and *S. aureus*, respectively, at 120 min. Experiments conducted under dark conditions did not show any remarkable change in the microbial colony counts, as less than 0.5-log reduction for both the microorganisms was achieved in 120 min (Figure 2c,d). Using the optimum concentration of Ag@ZnO nanoparticles for each of the bacteria for photocatalytic disinfection, comparative sunlight-assisted photocatalytic disinfection activity was evaluated with pure-ZnO and commercial TiO2 (Degussa P25) and the results are shown in Figure 4a,b. Figure 4c,d shows the Chick-Watson disinfection kinetics of *E. coli* and *S. aureus* using different photocatalysts. These results suggest the superior disinfection efficiency of Ag@ZnO nano-photocatalyst compared to the conventional metal oxide systems. An increase in inactivation for both targeted bacteria was observed with the increase in catalyst concentration from 1 to 2 mg/L in *E. coli* and 1 to 3 mg/L in *S. aureus*. With further increase in the catalyst concentration beyond the mentioned range, a deterioration in disinfection rate was obtained for both the targeted microorganisms. With lower concentration of catalyst the amount of reactive oxygen species (ROS) generated is comparatively less. Thus complete disinfection required a longer irradiation time [22]. It is expected that as the

rate of ROS production is slow at lower concentrations of catalyst, and under the initial conditions the microorganisms may activate their molecular resistance mechanisms. Therefore an extended disinfection time period is required for sufficient ROS generation and thus under the constant attack of ROS, bacteria may lose their capability of reactivation. With an increase in catalyst concentration the ROS generation rate increases, which is expected to improve the disinfection rate. Similarly, under the optimal conditions, the rate of ROS generation is maximum and therefore it may be expected that the interaction of the same with bacterial cells is more frequent. This may lead to an enhanced disinfection rate. It is further noticed that with increase in the catalyst concentration, disinfection gets delayed. This is mainly because with the increase in catalyst concentration the turbidity of the system increases, thereby blocking the sunlight irradiation from uniformly reaching the catalyst particles and cells, hence resulting in slower inactivation [23]. The current study involves *E. coli* and *S. aureus* bacteria. The photocatalytic performance of a photocatalyst depends both on its concentration and the irradiation time. *E. coli* was found more sensitive to sunlight-assisted photocatalytic disinfection process than *S. aureus*, as it requires comparatively less catalyst concentration and shorter sunlight irradiation time in comparison to *S. aureus* as evidenced from Figure 3a,b. The difference in susceptibility of both bacterial species to Ag@ZnO nanoparticles can be ascribed to the differences in their cell membrane/wall structures, chemical components, biological shape, and differences in robustness of Gram-positive and Gram-negative bacteria [24].

**Figure 3.** Effect of Ag@ZnO core-shell NPs loading on the solar-PCD kinetics of (**a**) *E. coli* and (**b**) *S. aureus*. Linear fitting plots of PCD kinetics of (**c**) *E. coli* and (**d**) *S. aureus* according to Chick-Watson model. Initial bacteria concentration = 5 × 106 CFU/mL, Temperature = 35 ± 2 ◦C. Error bars indicate the standard deviation of replicates (*n* = 3).

**Figure 4.** Effect of different catalysts on the solar-PCD kinetics of (**a**) *E. coli* and (**b**) *S. aureus* at a catalyst loading of 2 mg/L and 3 mg/L respectively. Linear fitting plots of PCD kinetics of different catalysts against (**c**) *E. coli* and (**d**) *S. aureus* according to Chick-Watson model at a catalyst loading. Initial bacteria concentration for each experiments = 5 × 106 CFU/mL, Temperature = 35 ± 2 ◦C. Error bars indicate the standard deviation of replicates (*n* = 3).

From Figure 4, it is observed that Ag@ZnO nanoparticles show enhanced disinfection efficiency for both targeted pathogens in comparison to the classical metal oxide systems (ZnO and TiO2). The expected reason behind the enhanced efficiency may be the positioning of the noble metal (i.e., Ag) in the core and encapsulating it with a ZnO shell. Photocatalytic disinfection involves the excitation of the photocatalyst with light energy greater than or equal to that of the band gap [25]. On excitation the electrons forming the valence band of the metal oxide shuttle to the conduction band, where they are usually accepted by electron acceptors present in the reaction environment. This reduction pathway leads to the formation of ROS which results in killing of microbial cells by damaging their membrane integrity [24,26]. Therefore it leads to subsequent release of the intra-cellular components, which become vulnerable to the ROS attack [26,27]. Figure 5a–d show the effect of temperature on the photocatalytic disinfection of the targeted pathogens. These results show that as the temperature increased, a maximum process efficiency was observed at a reaction temperature of 55 ◦C. It is thus observed that, the rate of disinfection improved as the temperature of the reaction system increased. At 55 ◦C disinfection is achieved within 45 min and 60 min for *E. coli* and *S. aureus*, respectively. The post-disinfection reactivation of the target microbes was monitored for 24 h. None of the microbes showed an6y reactivation thus suggesting cell death due to damage caused by the ROS to both the target pathogens.

**Figure 5.** Effect of different reaction temperature on the solar-PCD kinetics of (**a**) *E. coli* and (**c**) *S. aureus* at a catalyst loading of 2 mg/L and 3 mg/L respectively. Linear fitting plots of PCD kinetics of different reaction temperature against (**b**) *E. coli* and (**d**) *S. aureus* according to Chick-Watson model. Initial bacteria concentration for each experiments = 5 × 106 CFU/mL, Error bars indicate the standard deviation of replicates (*n* = 3).


Micro/Nanolithography A Heuristic Aspect on the Enduring Technology

*Edited by Jagannathan Thirumalai*

**MICRO/**

**NANOLITHOGRAPHY - A**

**HEURISTIC ASPECT ON**

Edited by **Jagannathan Thirumalai**

**THE ENDURING**

**TECHNOLOGY**


**NEUROIMAGING – COGNITIVE AND CLINICAL NEUROSCIENCE**

Edited by **Peter Bright**

http://dx.doi.org/10.5772/1815 Edited by Peter Bright

#### **Contributors**

Manuel Martin-Loeches, Pilar Casado, Trevor Archer, Roumen Kirov Kirov, Serge Brand, James Danckert, Seyed Mirsattari, Silvia Marino, Rosella Ciurleo, Silvia Guerrera, Annalisa Baglieri, Francesca Timpano, Francesco Corallo, Rosaria De Luca, Simona De Salvo, Placido Bramanti, Nicola De Stefano, Bonita L. Marks, Laurence Katz, Masahiro Kawasaki, Gioacchino Tedeschi, Fabrizio Esposito, Tom Verguts, Massimo Silvetti, Stephane Perrey, Nicolas Bourdillon, Satoru Yokoyama, Arlette Streri, Edouard Gentaz, Joshua Goh, Chih-Mao Huang, Stefan Golaszewski, Martin Seidl, Eugen Trinka, Eugen Gallasch, Raffaele Nardone, Franz Gerstenbrand, Chiung-Chih Chang, Wen-Neng Chang, Ya-Ting Chang, Shu-Hua Huang, Chun-Chung Lui, Chen-Chang Lee, Nai-Ching Chen, Lazaros Triarhou, Martin McKeown, Junning Li, Jane Wang, Agustin Ibanez, Phil Baker, Alvaro Moya, Bernardo Dell'Osso, Carlotta Palazzo, Cristina Dobrea, Laura Cremaschi, Chiara Arici, Beatrice Benatti, A. Carlo Altamura, Nobuhisa Kanahara, Eiji Shimizu, Yoshimoto Sekine, Masaomi Iyo, Michael Valenzuela, Chao Suo, Klaus Linkenkaer-Hansen, Fred Lenz

#### **© The Editor(s) and the Author(s) 2012**

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#### **Notice**

Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published chapters. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book.

First published in Croatia, 2012 by INTECH d.o.o. eBook (PDF) Published by IN TECH d.o.o. Place and year of publication of eBook (PDF): Rijeka, 2019. IntechOpen is the global imprint of IN TECH d.o.o. Printed in Croatia

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Abstract

Bioadsorbents were prepared in a simple manner only by treating in boiling concentrated sulfuric acid from various biomass materials such as various polysaccharides, persimmon tannin, cotton, paper and biomass wastes such as orange juice residue and microalgae residue after extracting biofuel. These bioadsorbents exhibited high selectivity only to gold over other metals and extraordinary high loading capacity for gold(III), which were elucidated to be attributable to the selective reduction of gold(III) ion to elemental gold due to its highest oxidationreduction potential of gold(III) of metal ions, catalyzed by the surface of bioadsorbents prepared in boiling sulfuric acid. By using these biosorbents, recovery of gold from actual samples of printed circuit boards of spent mobile phones and Mongolian gold ore was investigated. Recovery of trace concentration of gold(I) from simulated spent alkaline cyanide solution was also investigated using the bioadsorbent. Application of bioadsorbents to some recovery processes of gold from cyanide solutions was proposed.

Keywords: gold recovery, biomass materials


*2.7. Generating Random Values from the DPsL Distribution*

Random values from the DPsL distribution can be generated by following the algorithm given below.

$$y = -\frac{\beta}{\theta} - \frac{1}{\theta} \mathcal{W}\_{-1}(e^{-\beta}\beta(u-1))\_{\ast}$$

where *W*−1(*x*) denotes the negative branch of Lambert–W function.

3. Then, *x* = *y* represents a realization of a random variable with the DPsL distribution.

To generate a random sample of size *n*, repeat the algorithm *n* times.


**6. Conclusion**

Although the family planning program in Kenya appears to be doing well at the national level, experiences of women at sub-national levels suggest the need for targeted interventions to address challenges associated with contraceptive failure that might hamper the success of the program at the local levels. Interventions could include expanding the mix of available methods, provision of adequate information, improving counseling, as well as addressing health system factors that impede the provision of quality care such as limited staff skills, staff availability, inadequate supplies, and lack of or faulty equipment for administering longacting and permanent methods.


**3. Identification of thermal boundary conditions in heat exchangers of fluidized bed boilers**

Circulating fluidized bed (CFB) boilers burning coal or biomass are in use for several years. Fluidized bed combustion is widely used in power boilers due to its impressive environmental performance and also its fuel flexibility. Therefore, the studies of combustion and heat transfer are the subject of many recent investigations aimed at improving the design and operation of CFB boilers. Sun et al. [35] applied wide size biomass and investigated its combustion, heat transfer, and emission characteristics in CFB [35]. They found that co-firing wide screening crushed biomass pellets in CFB may reduce emissions and enhance heat transfer. Sundaresan and Kolar [36] conducted experiments to determine the total surface-average heat transfer coefficients from the tube to suspension for vertical tubes of different heights, which were placed in the core of a square cold CFB riser.

Superheaters and reheaters are the surfaces that achieve the highest temperatures in a boiler and for this reason require a lot of attention in the design, fabrication, operation, and mainte‐ nance to ensure that the permissible metal temperatures are never exceeded. A standard method for hydraulic calculation and design of boilers is described in [37]. The hydraulic calculation of superheater aims to provide the safe temperature of superheater tubes, efficient flow arrangement, and determination of pressure losses. Considerable attention has been given to hydraulic maldistribution in steam superheater tubes. A standard method for thermal design of steam boilers, including superheaters, was developed in [38]. Although the boiler standards are extensively used by manufacturers of boilers, they adopt for the calculation of the superheaters procedures which are used in design or performance calculations of usual heat exchangers assuming constant physical fluid properties [37–40]. For superheated steam, a constant value of the specific heat cannot be assumed because of the strong dependence on temperature. The specific heat of the water steam can decrease even twice over the length of the superheater tube.

The basic superheater and reheater design principles are discussed in detail by Rayaprolu [39]. Thermal and flow process in large steam boilers are the subject of the book [40]. Design and performance procedures for calculating of coal-fired boilers were described. Much attention has been paid to analyzing start-ups of steam boilers. Approximately 40% of all boiler failures are caused by damage of steam superheaters due to the overheating of the tube material [41]. Because of this, steam superheaters are modeled mathematically or monitored to avoid overheating of tubes. CFD simulations and optimization results of a 300 MW lignite-fired power boiler are presented by Tzolakis et al. [42]. A heat recovery steam generator (HRSG) was optimized by Behbahaninia using the genetic algorithm [43]. The results show that the thermodynamic optimization is not capable of decreasing significantly the total cost of the HRSG. Mathematical modeling of the boiler superheater was presented in not many publica‐ tions despite a great interest of boiler manufacturers. This is mainly due to the difficulty of the description of complex flow and heat transfer processes taking place in the steam superheaters both in pulverized coal and fluidized boilers. A numerical method for modeling of the superheaters in pulverized coal-fired boilers was developed in [44, 45]. Much trouble causes the flue-gas temperature unevenness in a duct where a superheater is situated. A thermal load deviation model for the superheater and reheater in a utility boiler is presented by Xu et al. [46]. Many failure analyses on the superheaters were carried out to reveal the causes of tube overheating or tube rapture. The unevenness of the steam temperature is one of the main reasons for boiler tube failures. The 320 MW natural gas-fired boiler was simulated using the CFD code by Rahimi et al. [47]. The main goal of the computational analysis was to detect the reason for the tube rupture inside the boiler. A new procedure for determining heat flux in superheater and reheater tubes based on the empirical formulas and the finite element modeling is presented by Purbolaksono et al. [48]. The finite element simulations were performed by Othman et al. [49] to find the main reason for superheater tube deformations. It was revealed that the failure of the tubes occurred due to the restriction of the tube deforma‐ tions. Local short-term overheating of the tubes due to concentrated flue-gas flow was the primary cause of superheater tube failure [50]. A failure analysis was carried out using visual inspections and in situ measurements of hardness the experimental examination was supple‐ mented by finite element analyzes. The rate of corrosive wear in superheaters of supercritical boilers was presented in the paper by Pronobis and Wojnar [51]. The slagging and fouling processes in superheaters influence the efficiency and lifetime of the boiler. Harding and O'Connor used the ten-year database to determine the lost generated through forced outages due to the coal quality or slagging and fouling issues [52]. A computer system for monitoring slagging and fouling of superheaters is described in [24].

performance and also its fuel flexibility. Therefore, the studies of combustion and heat transfer are the subject of many recent investigations aimed at improving the design and operation of CFB boilers. Sun et al. [35] applied wide size biomass and investigated its combustion, heat transfer, and emission characteristics in CFB [35]. They found that co-firing wide screening crushed biomass pellets in CFB may reduce emissions and enhance heat transfer. Sundaresan and Kolar [36] conducted experiments to determine the total surface-average heat transfer coefficients from the tube to suspension for vertical tubes of different heights, which were

Superheaters and reheaters are the surfaces that achieve the highest temperatures in a boiler and for this reason require a lot of attention in the design, fabrication, operation, and mainte‐ nance to ensure that the permissible metal temperatures are never exceeded. A standard method for hydraulic calculation and design of boilers is described in [37]. The hydraulic calculation of superheater aims to provide the safe temperature of superheater tubes, efficient flow arrangement, and determination of pressure losses. Considerable attention has been given to hydraulic maldistribution in steam superheater tubes. A standard method for thermal design of steam boilers, including superheaters, was developed in [38]. Although the boiler standards are extensively used by manufacturers of boilers, they adopt for the calculation of the superheaters procedures which are used in design or performance calculations of usual heat exchangers assuming constant physical fluid properties [37–40]. For superheated steam, a constant value of the specific heat cannot be assumed because of the strong dependence on temperature. The specific heat of the water steam can decrease even twice over the length of

The basic superheater and reheater design principles are discussed in detail by Rayaprolu [39]. Thermal and flow process in large steam boilers are the subject of the book [40]. Design and performance procedures for calculating of coal-fired boilers were described. Much attention has been paid to analyzing start-ups of steam boilers. Approximately 40% of all boiler failures are caused by damage of steam superheaters due to the overheating of the tube material [41]. Because of this, steam superheaters are modeled mathematically or monitored to avoid overheating of tubes. CFD simulations and optimization results of a 300 MW lignite-fired power boiler are presented by Tzolakis et al. [42]. A heat recovery steam generator (HRSG) was optimized by Behbahaninia using the genetic algorithm [43]. The results show that the thermodynamic optimization is not capable of decreasing significantly the total cost of the HRSG. Mathematical modeling of the boiler superheater was presented in not many publica‐ tions despite a great interest of boiler manufacturers. This is mainly due to the difficulty of the description of complex flow and heat transfer processes taking place in the steam superheaters both in pulverized coal and fluidized boilers. A numerical method for modeling of the superheaters in pulverized coal-fired boilers was developed in [44, 45]. Much trouble causes the flue-gas temperature unevenness in a duct where a superheater is situated. A thermal load deviation model for the superheater and reheater in a utility boiler is presented by Xu et al. [46]. Many failure analyses on the superheaters were carried out to reveal the causes of tube overheating or tube rapture. The unevenness of the steam temperature is one of the main reasons for boiler tube failures. The 320 MW natural gas-fired boiler was simulated using the

placed in the core of a square cold CFB riser.

236 Numerical Simulation - From Brain Imaging to Turbulent Flows

the superheater tube.

Direct and inverse problems in a platen superheater situated in the combustion chamber of a CFB boiler were studied in [2].

The review of the state of the art in the field of superheaters shows that published papers on the superheaters present mostly experimental results and relate to search for the causes of failures of superheater tubes or analyze ash fouling.

In this work, the finite volume modeling of a platen superheater is presented. The fluidized bed boilers steam superheaters are placed in the combustion chamber and are made of tubes with non-circular cross sections, to avoid erosion and slagging (**Figure 17**). Due to the complex shape of the cross section of superheater tubes (**Figure 18**), numerical modeling has been applied to correctly determine the temperature distribution of steam and tube wall. Accurate calculating the superheater tube wall temperature is necessary because of the high prices of alloy steels used in superheater manufacturing.

A CFD simulation will be carried out for the platen superheater located in the combustion chamber of the CFB boiler. The second stage superheater is situated in the upper part of the combustion chamber of a circulating fluidized bed boiler (CFB boiler) with the capacity of 425 · 103 kg/h steam. The steam boiler with a live steam temperature equal 560°C and a pressure of 16.1 MPa has an atmospheric circulating fluidized bed furnace. The superheater is a threepass heat exchanger. The water steam flows inside the tubes while the flue gas with a constant temperature flows upwards in a perpendicular direction to the tube axes. Two inverse problems will be solved. First, the flue-gas side heat transfer coefficient *hg* will be determined using temperatures measured at the outlet and inlet of the heat exchanger. This coefficient is essential for the proper design of superheaters in fluidized bed boilers. In the second inverse problem, in addition, to the heat transfer coefficient *hg* will also be searched the steam tem‐ perature at the inlet to the superheater based on the measured steam temperatures at three points located at the ends of the superheater passes. Such inverse problem is encountered in a superheater steam temperature controllers.

**Figure 17.** The arrangement of heating surfaces in circulating fluidized bed boiler with a steam capacity of 425·103 kg/h.

On modern large steam boilers, the temperature must be held close to design values since excessive temperatures have a serious effect on the metal lifetime of all parts of a boiler which are subject to it. The inlet steam temperature will be determined from the solution of the inverse problem. Based on this temperature, a correct flow rate of cooling water to the spray-type desuperheater (attemperator) is calculated. Despite the great practical importance, this type inverse heat transfer problems have not yet been analyzed.

Solving Inverse Heat Transfer Problems When Using CFD Modeling http://dx.doi.org/10.5772/63807 239

**Figure 18.** Platen superheater made from "omega" tubes; (a) cross section of omega tube, (b) platen superheater crosssection.

**Figure 17.** The arrangement of heating surfaces in circulating fluidized bed boiler with a steam capacity of

inverse heat transfer problems have not yet been analyzed.

238 Numerical Simulation - From Brain Imaging to Turbulent Flows

On modern large steam boilers, the temperature must be held close to design values since excessive temperatures have a serious effect on the metal lifetime of all parts of a boiler which are subject to it. The inlet steam temperature will be determined from the solution of the inverse problem. Based on this temperature, a correct flow rate of cooling water to the spray-type desuperheater (attemperator) is calculated. Despite the great practical importance, this type

425·103

kg/h.


5. Conclusion

near crack tip and normal field Ω far away from crack tip, as shown in Figure 9. Ordinary finite element mesh is constructed in normal field; self-similar mesh needs to be constructed

Self-similar mesh is shown in Figure 10. In singular field, infinite curves f g Γ1; Γ2; Γ3; ⋯ similar to Γ0 are generated based on the proportionally coefficient ξð Þ 0 < ξ < 1 regarding crack tip as centre. The density of fractal mesh is controlled by ξ. Based on appropriate global interpolation function and fractal transforming technique, plenty of unknown degrees on slave nodes are

based on fractal theory in singular field.

248 Contact and Fracture Mechanics

Figure 9. Illustration of division of structure with crack.

Figure 10. Self-similar mesh in singular field.

This chapter reviews the most common empirical models and numerical methods of structural fatigue lifetime prediction. The main advantages and disadvantages of these methods are discussed.

Numerical method based on empirical models, as one of significant ways to analyze structural fatigue life, becomes popular in structural life prediction nowadays because of less cost and higher efficiency.

S N curve and ε N are applied to high-cycle and low-cycle fatigue problems, respectively. And there are many modified models considering mean stress or stress ratio. However, this chapter further shows that part of these models are too complicated to apply to engineering, and other models are only valid in some specific cases.

Paris law is the most significant model of crack propagation problem. But it only considers the stress intensity factor as the factors make influences on crack propagation. Many improved models considering stress ratio, crack closure, crack retardation, and crack propagation threshold have been put forward.

FEM is the most popular numerical method to obtain stress intensity factor or crack growth route. Extended finite element method and fractal finite element method are two mainly developing trends of FEM. However, it is still difficult to achieve high efficiency and accuracy of numerical method at the same time.


1. Introduction

The association between inadequate intake of energy and nutrients before and during pregnancy and severe maternal outcomes has been well documented in the observational studies. It is crucial for women to be fully aware of nutrition requirements without waiting until getting a positive pregnancy test result. The reason for this is that there are major changes associated with metabolism and physiology to support embryo development in the mother. The mother's diet is the only source of nutrition for her baby. Maternal undernutrition may affect the developing baby. Weight gain is a part of healthy pregnancy, but the recommendation for an optimal gestational weight gain is still controversial, especially in Asian countries. Moreover, some observational studies have shown that gestational diabetes and nutrient deficiencies during pregnancy may need to be considered differently for an individual's prenatal body mass index (BMI). Thus, in this chapter, an attempt was made to address these issues. Moreover, the role of personalized nutritional counseling, as discussed in each issue, needs to be understood carefully.

## 2. Gestational weight gain

Getting pregnant leads to significant changes of weight in the body of women. It is normal for women to put on more weight in the last two trimesters than the first trimester as it supports the growth of fetus, the placental development, and amniotic fluid as time goes. However, putting on weight very quick per week (i.e., 0.5–1 kg in a week) is strongly associated with a life-threatening condition, such as preeclampsia [1, 2], so it is worth to notice healthcare professionals about abnormal weight gain. A woman with prepregnancy overweight and obesity should take a plan of gestational weight gain GWG into account during prenatal visits. A cohort study of 3539 women with a follow-up period of 17 years demonstrated that overweight women (BMI > 25) at the beginning of pregnancy had an increased risk of diabetes, cardiac disease, or endocrine diseases later in their life [1]. Moreover, excessive or inadequate weight-gain levels during pregnancy can affect small or large gestational age, an increased risk of cesarean delivery, and other adverse pregnancy outcomes, including gestational diabetes mellitus and preeclampsia [1–4].

The Worth Health Organization definition of body mass index (BMI) is "a person's weight in kilograms divided by the square of the person's height in meters (kg/m2 )." For instance, a pregnant woman who weighs 50 kg and her height is 1.6 m will have a BMI of 19.5. BMI has been well recognized as an effective measurement to identify overweight and subsequent health risks in an individual. The increasing level of BMI from overweight to extreme obese is thought to accompany the increasing risk of health problems (Canadian Health Guideline 2004). The American Institute of Medicine (IOM) recommended the ideal amount of weight gained during pregnancy based on WHO-BMI ranges from underweight to obesity, but not all obesity classes were addressed (Table 1). The origin of the IOM recommendations about gestational weight gain (GWG) came primarily from the American population-based studies despite its popular applicability to European and Asian countries. In the Asian population-based studies reviewed, the recommendations of the IOM concerning gestational weight gain (GWG) have limited applicability for Asian women to get their desired GWG. The accumulated evidence on noncommunicable diseases demonstrated that Asian adults get more body fat and have greater risks of diabetes and cardiovascular diseases at their lower BMI in comparison with non-Asian population. Thus, Asian regional BMI cutoff points [6] developed by the panel of WHO consultation minimize these risks (Table 2). A large meta-analysis study with more than 300,000 Asian women confirmed that the IOM recommendations about GWG can be applicable in Asian countries when using regional BMI cutoff points for overweight or obese [7]. The evidence was not attempted to define a GWS guideline for all Asian women as the data of this study were based primarily on East Asian countries, such as China, Taiwan, Korea, and Japan. Moreover, Korean and Taiwanese women tend to gain more weight during pregnancy than other Asian women [8]. This requires more comparative studies in Asia. However, its strength confirmed that the guideline for GWG may need to be considered differently for Asian women. To date, a global consensus regarding a desired GWG is still understudied.

### Table 1.

Recommended weight gain during pregnancy based on the 2009 Institute of Medicine (IOM) guideline [5].

\*These recommendations suggested by the author should only be used as a reference for public health strategists, nutritional practitioners, or healthcare professionals in Asia. These recommendations were based on ideas in a large meta-analysis study [7]; thus, they are not considered as a completed guideline.

### Table 2.

The proposed gestational weight gain recommendation based on Asian regional BMI cutoff points [6].

An excessive amount of weight gained during pregnancy could be predictive of weight retention at 6 months postpartum [2] and of an increased risk of weight management challenges later in life [3, 4]. A meta-analytic study of over 65,000 women by Nehring et al. demonstrated that women with GWG above the IOM recommendations were likely to have an additional gain of 3 kg at 3 years and of 4.7 kg at 15 years after pregnancy, compared to those with GWG within the recommendations [3].

## 2.1 Brief nutrition recommendations for gestational weight gain

Transitions to a new weight gain during a pregnancy may need to meet additional calories every day. According to the IOM expert panel's recommendation on macronutrients for pregnant women with normal BMI, an estimation of additional 0, 340, and 452 kcal for the first, second, and third trimester, respectively [9, 10] was recommended. Moreover, additional calories should also be personalized to an individual's prenatal BMI [10].

Adding small meals or one or two extra snacks during the day may facilitate these targets. There is no need to stick on high-energy density diets, but, a balanced diet with nutrient-dense foods has the benefit of providing a range of vitamins and minerals.

## 3. Management of gestational diabetes mellitus during pregnancy

Gestational diabetes mellitus (GDM) is one of the common pregnancy complications related to diet. Pregnancy is related with a biological reduction of insulin sensitivity by about 60% [15], which supports fetus development by an increase of glucose into the placenta. Some women were present with elevated blood glucose levels during their pregnancy although no diabetes was diagnosed before their pregnancy. The excessive blood glucose level can cause hyperglycemia which will develop gestational diabetes mellitus. Fortunately, the well-managed blood glucose levels typically turn normal after delivery. GDM globally happens in about 3–28% of pregnant women. The prevalence of GDM in European countries is about 5.4%, while 10.1% GDM occurs in Eastern and Southeastern Asian countries, except in Indonesia, the Philippines, Myanmar, Cambodia, and Laos [16]. Among the latter, Vietnam and Singapore have the greatest prevalence of GDM (about 20%). The prevalence of diabetes during a pregnancy has been increasing markedly in Africa and Asia [16]. It is closely associated with the increase of obesity and sedentary lifestyle. It is the most common medical complication during a pregnancy. Women with a healthy weight can be affected. This is likely due to participation of pregnancy-related hormones, such as human placental lactogen (HPL). A 30-fold increase of HPL by the 20th week of gestation causes improperly elevated blood sugar levels, which contributes to the developing GDM between the second and the third trimester [17, 18]. However, women who enter into pregnancy overweight or obese are at a markedly increased risk of developing GDM. The increased release of pro-inflammatory cytokines and adiponectin was associated with an accumulation of adipose tissues, particularly with central obesity [19–21]. These releases contribute to a severe GDM, including increased glucose blood levels [22], endoplasmic reticulum stress [23], and increased insulin resistance [21, 24]. Women, diagnosed with a lower adiponectin concentration at their early trimester, are likely to develop an increased insulin resistance and GDM later in their semesters [25].

Several adverse outcomes are associated with diabetes during a pregnancy: mothers with the untreated GDM have a higher risk of hypertension, preeclampsia, cesarean delivery, and labor complications; their babies are at increased risk of macrosomia, large for gestational age, fetal organomegaly, shoulder dystocia, hypoglycemia, and perinatal morbidity and mortality due to the excessive glucose flux into the placenta [26, 27].

### 3.1 Nutritional therapy for gestational diabetes mellitus

The role of nutrition in the management of gestational diabetes mellitus is now drawing considerable attention in public because of the natural process without side effects for women and their unborn baby. Diet-based interventions in the pregnancy aim to control maternal hyperglycemia as well as to lower risks of macrosomia. The concept of these interventions is a three-step nutritional therapy (NT), including a personalized dietary counseling, appropriate energy restriction, and promotion of a balanced diet.

Some observational studies reviewed that it is beneficial for women to take three-step NT into consideration in prenatal or early pregnancy visits if they have one or more of the following contributory factors for GDM [28–30]:

1. Being overweight or obese (BMI cut offs ≥23 kg/m2 for Asian population; BMI ≥ 25 kg/m2 for non-Asian population)

### 3.2 A personalized counseling for GDM

Women with diagnosed gestational diabetes need to be put on a proper diet. Thus, they should seek a tailored nutritional counseling by a registered nutritional therapist. Personalized dietary counseling was associated with a well-controlled maternal hyperglycemia and a proper weight gain due to the mothers' better awareness about GDM and meal plans [31, 32]. The dietary counseling needs to be tailored for an individual; this consists of things like not only her diet and lifestyle but her expectation and barrier. For instance, the nutritional advice on a restricted diet of fast foods should also discuss about where a patient can get healthy foods and her related barriers. Moreover, understanding the effects of the dietary advice on not only an individual but also her family members has shown the significant improvement of clinical outcomes [33, 34]. This is likely due to family member's additional support.

Some meta-analysis and systematic review studies demonstrated that women with GDM had encountered the weight management, in particular overweight or obese people [32]. A majority of these cases are largely associated with their unhealthy lifestyle choices, including low physical activities, problematic portion control, and poor diet. In the context, the counseling needs to take these issues into consideration. Moreover, it is important to promote healthy food choices in the consultation. Importantly, the nutritional advice for GDM is tailored, relevant, and applicable to the patient.

### 3.3 Energy restriction and appropriate weight gain for GDM

Energy restriction aims to ensure that women and their babies get enough energy to develop and grow, but minimizes the reductant amount of weight gained. The influence of energy balance on dietary macronutrient intake and physical activity could be considered as a primary factor in the reduced fat composition. There is some established evidence that moderate caloric restriction can improve maternal hyperglycemia as well as reduce insulin requirement, but, there is no association between restricted caloric intake and birth weight. However, severe caloric restriction to either less than 1200 kcal per day or 50% of daily energy

### Complications of Pregnancy

requirement is related to the production of ketonuria and ketonemia, which is called ketosis [35, 36]. According to the recommendations of American Diabetes Association about energy restriction, obese women with GDM can benefit from a 30–33% energy restriction or a limit of 25 kcal per kg per day, but there was no report related to GDM women with normal weight [35, 37, 38]. Some studies suggested a caloric restriction of 30–34 kcal/kg (actual weight of pregnant women) for those with normal BMI [36]. However, further interventional studies are needed to take this recommendation into action.

## 3.4 Promotion of a balanced diet with high fiber and low carbohydrate

The transport of glucose into the placenta depends on how accelerated the mother's postprandial blood glucose concentrations are. The excessive amount of glucose crosses the placenta, which can affect birth weight. A postprandial high blood glucose levels in GDM women is typically higher. Insulin is a metabolic hormone released from beta-cells in the pancreas, which play an essential role in the blood glucose regulation. Dietary carbohydrate is absorbed into the intestine and converted into simple glucose, which leads to a significant increase of maternal blood glucose concentrations. After a meal, GDM women found normoglycemia very challenging. They sometimes need medications to turn their blood glucose normal. One of the major purposes in the GDM nutritional management is thus to achieve normoglycemia after meal. The postprandial blood glucose level depends on the amount of glucose absorbed in the intestine and released into the bloodstream. There is some established evidence that a diet rich in fibrous carbohydrate, such as vegetables and fruits, and low in starchy and high glycemic index carbohydrate, may be helpful to reduce postprandial blood glucose as well as to change body fat composition [39, 40]. The American Diabetes Association guideline focuses on how much energy from dietary carbohydrate a GDM woman consumes [41]. The guideline demonstrated that the consumption of dietary carbohydrate among women with GDM should be limited to 40–45% of total daily energy, with a smaller percentage at breakfast than at lunch or dinner.

Glycemic index (GI) is a measurement related to the amount of carbohydrate in certain foods and its effect on a blood glucose increase after eating, a rank of values from 0 to 100. A high GI in foods (≥70) causes a sharp increase in blood glucose compared with a food with a medium (56–69) or low GI (≤55). Some established evidence recommended that the GDM women can consume low GI or complex carbohydrates, even greater than 45% of the total energy, without a quick response of increased blood glucose [42, 43]. Glycemic control can be achieved by increasing the consumption of foods with low GI, such as whole grains, green vegetables, and legumes, instead of high-GI foods like potatoes or sweet foods. Rice, a starchy food, is routinely eaten by 60% of world population, primarily in Asian countries. Approximately three-fourths of the total carbohydrate calorie requirement in Southeast Asia comes from rice [44]. Like potatoes or white breads in western countries, white rice can be a staple part of Asian meals. Unfortunately, the refined white rice may increase risk of hyperglycemia. It is a challenge for Asian women with GDM to avoid white rice due to its preferred taste or flavor, but following a low-GI diet guideline along with white rice will facilitate their glycemic control (Table 3). Several conventional studies demonstrated that the different types of rice have variations in GI value. For instance, among 12 types of rice commercially available in the United Kingdom, a nonblind, randomized trial indicated that rice noodles, long-grain rice, white basmati rice, and easy-cook long-grain rice were classified as low-GI foods, compared with others [45]. This is likely due to the difference in amylose composition and its effect on gelatinization [46, 47] rather

Table 3.

Recommended low-GI diet for Asian pregnancy with GDM.

than the dietary fiber content solely [46]. Rice with higher amylose composition has greater GI. The gelatinization represents the thickening of starch granules when heated in the presence of water. Thus, rice with greater gelatinization, such as glutinous rice, will have higher GI [48].

The evidence stated that the consumption of a high amount of fat, particularly with saturated fatty acids, can affect both the insulin-induced signaling pathway on cell membranes and lipid metabolism after a meal [49, 50]. Saturated fatty acids in strong relation to insulin resistance are well documented in not only epidemiological but also intervention studies [51]. Moon demonstrated that diets rich in saturates appear to impair the insulin-induced normal signaling by reducing IRS-1 expression and phosphorylated PI3K levels [52]. This results in significantly decreased transfer of glucose across the muscle cell membrane via GLUT-4, glucose transporter proteins, and the increased serum glucose. In addition, in a current study on mice with impaired Toll-like receptor-4, Zhou also demonstrated that saturated fatty acids are associated with glucose intolerance through reducing functions of nucleotidebinding oligomerization domain 1 (NOD1) in insulin-stimulated glucose uptake in adipocytes [53]. Thus, women with GDM may need to avoid saturated fats, but increase consumption of polyunsaturated fatty acids, especially fish oil [54]. A randomized double-blinded, placebo-controlled trial on fish oil supplementation and its effects on GDM demonstrated that omega-3 supplementation was associated with upgraded expression of genes related to insulin activities and inflammation among GDM women [55]. To date, taking omega-3 supplements routinely has not been recommended for the treatment of GDM due to lack of evidence. However, omega-3 supplements may need to be considered additionally for pregnant women if they find fish consumption challenging.

## 4. Management of vitamin D deficiency during pregnancy

Vitamin D is essential for absorption of dietary calcium and phosphate in the small intestine and for the deposition of calcium and phosphate in the mother's bones, and for her baby's as well. Moreover, maternal vitamin D was known as the only source for the unborn baby. Gestational vitamin D deficiency during pregnancy is related to infantile rickets. Moreover, the lack of vitamin D in the first trimester of pregnancy is predictable to preeclampsia and gestational diabetes mellitus [56, 57]. Maternal vitamin D is primarily synthesized under her skin while exposed to sunlight. First, due to sunlight, the 7-dehydrocholesterol under skin will be converted into cholecalciferol (vitamin D3). Then, the hydroxylation of vitamin D3 in the liver occurs to form 25(OH)D. Finally, 25(OH)D is continuously hydroxylated in the kidney to become a biologically more active form, 1,25(OH) 2D. Serum 25(OH)D concentrations are clinically measured to indicate an individual's vitamin D status due to its stable half-life of 2–3 weeks. There is some established evidence that inadequate serum vitamin D concentrations at early childhood puts individuals into a higher risk of metabolic disorders later in their life, such as heart disease and diabetes as vitamin D receptors are present in almost tissues.

Those women who smoke, use sunscreen, or cover their skin with clothing increase significantly risk of vitamin D deficiency. Unfortunately, some individuals have encountered getting an adequate amount of vitamin D due to their darker skin tone. A global sunshine calendar developed by the Vitamin D Day (https://www. vitamindday.net/) suggested a practical tip for an individual to get enough vitamin D while exposed to sunlight, no matter where he or she lives.

One of the biggest concerns about getting vitamin D from sun is skin cancer due to ultraviolet (UV) radiation exposure. There was an association between less education and misconception of vitamin D from sunlight. A cross-sectional survey of 3922 participants in the United States demonstrated that individuals with a high school diploma or less had misconception of a longer sunlight exposure related to achievement of a sufficient vitamin D, which may need more studies about vitamin D-related sun exposure behaviors and risk of skin cancer [58]. In natal visits, it is important for registered nutritional practitioners to take women's vitamin D knowledge as well as their sun safety behaviors into consideration [59].

Mushroom, oily fish, egg yolks, and vitamin D fortified milk is a dietary source of vitamin D. Oral vitamin D supplementation is as available as drops or tables, which can be taken over the counter or on registered nutritional practitioner's prescription. Oral vitamin D supplementations among pregnant population have shown to improve maternal vitamin D status and lower risk of premature birth delivery. According to the guideline of the Royal College of Obstetrics and Gynecology (RCOG), a daily vitamin D supplementation of 400 units is recommended for women with singleton gestation [60]. To date, there is still no vitamin D guideline for twin or multiple pregnancies although it shares an increased risk of gestational outcomes. Some experts from the Society of Maternal Fetal Medicine suggested that women with twin gestations should consume daily vitamin D supplementations of 1000 units [61]. Oral vitamin D supplementations within the guideline, plus sunlight exposure, will not lead to symptoms of excessive vitamin D.

There is a hypothetical concern that which is better: taking vitamin D supplementation alone or in combination with calcium? The evidence from a Cochrane systematic review confirmed that the consumption of vitamin D combined with calcium is related to an increased risk of premature birth [62]. The effect and cause behind the evidence were not well documented. Thus, it is important for the registered nutritional practitioners or nutritional therapist to take measures to

### Undernutrition during Pregnancy DOI: http://dx.doi.org/10.5772/intechopen.82727

manage this risk when making a description of vitamin D combined with calcium for preeclampsia. It is beneficial for public to take vitamin D supplement alone over the counter within the guideline.

Women who enter into pregnancy obese are also at increased risk of nutrient deficiencies, in particular, deficiencies of vitamin D. Also in pregnant women, BMI is inversely associated with the serum concentrations of vitamin D. Obese women are at a markedly increased risk of vitamin D deficiency compared to women with BMI in the normal range, and the offsprings of obese women also have lower levels of vitamin D in their cord blood. The prevalence of vitamin D deficiency in pregnant women can be quite high in some populations, reaching, for example, one third in the USA, 35% in the UK, and 77% in Germany [63]. Vitamin D is believed to be sequestered in the adipose tissue, making it less available in obese people.

Hence, obese women have an even higher prevalence of vitamin D deficiency during pregnancy. Recently, the RCOG guidelines recommended that obese pregnant women should be taking at least 1000 units a day of vitamin D supplementation, compared with a daily vitamin D supplementation of 400 units for those women with healthy BMI [60, 64].

Women at higher risk of vitamin D deficiency, such as obesity, need to follow a maternal vitamin D assessment in prenatal, first trimester, and last trimester visits to ensure a proper vitamin D supplementation.

### 5. Management of folic acid deficiency during pregnancy

Folate or vitamin B9, a family member of water-soluble vitamins, plays an important role in the production of neurotransmitters and synthesis of DNA in cells, especially in early pregnancy. Folate is naturally found in dark green leafy vegetables and legumes while folic acid, a synthetic form of vitamin B9, is generally added in supplements or fortified milk or foods. Folate deficiency in pregnancy generally occurs when maternal dietary supply does not meet a suddenly increased folate requirement for the embryogenesis [65]. This requires an adequate amount of folate prior to conception and continuing throughout within next 28 days, an essential period of neural tube formation. The failure will lead to abnormal fetus development, even death. New parents are often unaware of their pregnancy as well as unprepared of an increased folate demand of this important event [65, 66].

All pregnant women need to consume a daily folate supplementation of 400 μg or 0.4 mg. Folate deficiency is strongly associated with abnormal neural tube development. Evidence has shown that the risk of neural tube defects among obese pregnant women is double that of women with normal BMI. As a result, a higher dosage of folate supplementation is recommended for pregnant women with high BMI. It is important for these women to take this raised amount of folic acid at least a month prior to conception to their first trimester. The Center for Maternal and Child Enquiry jointly with the Royal College of Obstetrics and Gynecology recommends that women with a body mass index higher than 29.9 should take a supplement on top of their diet, with 5 mg of folic acid daily [67]. In contrast, the recommended folic acid dosage for women with a healthy BMI, of course, is only 0.4 mg daily.

### 6. DHA in a pregnancy

Omega-3 docosahexaenoic acid (DHA; 22:6n-3) is an important component in the cell membrane, specially brain cells. It has been postulated that low maternal

DHA concentrations could be related with increased risk of postpartum depression and preterm birth. During the embryogenesis, maternal DHA levels significantly increased, which may contribute to reduce oxidative stress-induced impairment of the neurotrophic factors [68]. Omega-3 DHA is pronouncedly found in a fetus brain from the last trimester to 12 months after delivery [69, 70]. Oily fish, river eels, and wide carps are often a rich source of omega-3 essential fatty acids (FA). DHA in the diet can be obtained from river eels, wide carps, and marine-derived fatty fish, such as salmon, mackerel, anchovies, sardines, and sea trout. One of the biggest concerns about seafood consumption is risk of mercury exposure. According to the United States Environmental Protection Agency (EPA)'s fish advice, it is safe for pregnant women to consume 2 servings (6.2 ounces or 175 g) of certain cooked fish with a low average mercury concentration (≤0.15 μg/g) [71, 72]. Some oily fish species labeled as "the best choice to consume" are Atlantic mackerels, anchovies, herrings, haddocks, lobsters, salmon, sardine, and light tuna. However, women, who might become pregnant, should avoid or consume less than 100 g per week predatory fish species, such as bigeye tuna, swordfish, marline, shark, and orange roughy [73–75]. Alternatively, oral DHA supplementation alone of 200–300 mg was recommended for all pregnant women [72].


*4.2. Corrosion of Individual Phases*

Based on the SEM investigation, it can be concluded that individual phases are corroding in the following order: α(Al) → MgxZny → Mg2Sn (if present) → η(Zn).

For α(Al), MgxZny and η(Zn) this order corresponds with their respective corrosion potentials reported in the literature as seen in Figure 13. On the contrary, Mg2Sn behaves as a more noble phase compared to α(Al) and MgxZny phases despite having a lower OCP compared to these phases. A clear example is given in Figure 14a, where already in an early stage of the corrosion attack, an Mg2Zn11 particle is affected by the corrosion when in contact with an Mg2Sn particle. Such a phenomenon can be caused by several factors, such as for example a local change in pH, or local change in chemical composition of these Mg2Sn particles. The second phenomenon was regularly observed in all Sn-containing alloys. During the corrosion, the local dealloying of Mg2Sn particles occurs. Mg2Sn particles are separated into Mg and Sn atoms. Mg is most probably immediately forming new corrosion products, while Sn resides in the form of metallic particles. These can be observed on most BSEM images of the areas affected by the IG corrosion. As shown in Figure 14b, even the formation of an Sn-rich shell can be observed on larger particles found in the annealed samples. The Mg content of former Mg2Sn particles is being gradually reduced, hence, the remaining metallic particle will have locally a higher potential compared to neighbouring microstructure components. As a final stage, pure Sn particles are formed in the place of Mg2Sn particles. This process is even described by several authors [28–31] as a potential energy storage system for batteries. The final stage of this process is documented in Figure 15a. The corresponding EDS maps in Figure 15b confirm the presence of Snbased metallic particles. Mg and O maps are overlapping, indicating that Mg is forming corrosion products.

**Figure 14.** Behaviour of Mg2Sn intermetallic phase during corrosion (MZ + 2.0Sn, annealed): (**a**) Influence of Mg2Sn on initial stage of corrosion of Mg2Zn11 intermetallic particle; (**b**) dealloying of Mg2Sn particle.

**Figure 15.** Details of Mg2Sn particles affected by dealloying (MZ + 3.0Sn, annealed): (**a**) overview BSEM image; (**b**) chemical element distribution maps of Mg, O, Sn and Zn.

#### *4.3. Phase Composition of Corrosion Products*

Hydrozincite and simonkolleite are the most common corrosion products reported by several authors for similar alloy systems [18–20,32,33,36–38]. This is in good agreement with the current results.

The semi-quantitative analysis showed that a slightly higher portion of simonkolleite was found in the corrosion products of both as-cast and annealed pure Zn samples compared to MZ + xSn alloys. This is in line with the observation of Prosek et al. [32], where simonkolleite was more likely to be identified for pure Zn coatings. As the XRD analysis could not give the data on the chemical composition of these phases, the presence of Mg and Al in the corrosion products of MZ-based alloys was measured by the SEM EDS analysis with up to 2 wt.% of Mg and up to 1 wt.% of Al. From the two main corrosion products, the hydrozincite can accommodate Mg as a metallic ion in its structure [45,46]. This would support our observation, where the increased amount of the hydrozincite was identified on the MZ + xSn samples compared to pure Zn.

Additionally, layered double hydroxide (LDH) phases were identified, where LDH can represent a group of similar phases [18–20,32,36,39,47]. Azevedo et al. [20] identified LDH within the corrosion products formed on a Zn3.7Al3.0Mg alloy coating after 100 h of NSST (5% NaCl). Applying the Rietveld method refinement to their XRD pattern revealed that about 2–3 vol.% of the corrosion products were formed by LDH (ICSD FIZ Karlsruhe database 98-015-5051). Similarly, a low amount of LDH was indicated by the semi-quantitative results of Prosek et al. [32] within the corrosion products of Zn1.5Al1.5Mg alloy coatings exposed to model atmospheric conditions. However, in the studied system, LDH was not confirmed in any of our measurements, not even during GI XRD measurements performed directly on the corroded surface with the loose corrosion products removed. When comparing our experiments to the literature, there are two probable causes: we had rather low Al and Mg content compared to NSST done by Azevedo et al. [20]. Prosek et al. [32] used the same coating, however, in a very different corrosion environment. We might have a specific combination of parameters, which are not favourable for the creation of LDH.


**Acknowledgement**

This work was supported by OTKA-81522 for GMN. Thanks are due to Mariann Akocsi for her excellent technical help preparing this manuscript.

The Role of Prolactin in the Regulation of Male Copulatory Behavior 145

[10] Bitran D, Hull EM (1987) Pharmacological Analysis of Male Rat Sexual Behavior.

[11] Doherty PC, Baum MJ, Todd RB (1986) Effects of Chronic Hyperprolactinemia on Sexual Arousal and Erectile Function in Male Rats. Neuroendocrinology 42:368-75. [12] Doherty PC, Bartke A, Smith MS, Davis SL (1985) Increased Serum Prolactin Levels Mediate the Suppressive Effects of Ectopic Pituitary Grafts on Copulatory Behavior in

[13] Kalra PS, Simpkins JW, Luttge WG, Kalra SP (1983) Effects on Male Sex Behavior and Preoptic Dopamine Neurons of Hyperprolactinemia Induced by MtTW15 Pituitary

[14] Weber RF, Ooms MP, Vreeburg JT (1982) Effects of Prolactin-Secreting Tumour on

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[16] Svare B, Bartke A, Doherty P, Mason I, Michael SD, Smith MS (1979) Hyperprolactinemia Suppresses Copulatory Behavior in Male Rats and Mice. Biol

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[18] Juan M. Dominguez, Elaine M. Hull (2005) Dopamine, the medial preoptic area, and

[19] Stammel W, Thomas H, Staib W, Kühn-Velten WN (1991) Tetrahydroisoquinoline alkaloids mimic direct but not receptor-mediated inhibitory effects of estrogens and phytoestrogens on testicular endocrine function. Possible significance for Leydig cell

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### **5. References**

<sup>\*</sup> Corresponding Author

[10] Bitran D, Hull EM (1987) Pharmacological Analysis of Male Rat Sexual Behavior. Neurosci Biobehav Rev. 11:365-89.

144 Prolactin

**Author details**

*Budapest, Hungary*

**5. References**

**Acknowledgement**

*Tokyo, Japan*

Toru R. Saito and Misao Terada

Márk Oláh and György M. Nagy\*

Fertil steril 27: 1425-1427.

79: 1002-1010.

112:215-20.

Corresponding Author

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Female Rats. Science 227: 782-784.

Hypognadism. Acta endocrinol 88: 131-146.

receptor knockout mice. Endocr Rev. 19(3):225-68.

*Behavioral Neuroscience Section, Nippon Veterinary and Life Science University,*

This work was supported by OTKA-81522 for GMN. Thanks are due to Mariann Akocsi for

[1] Weizman A, Weizman R, Hart J Maoz B, Wijsenbeek H, Ben David M (1983) The correlation of Increased Serum Prolactin levels with Decreased Sexual Desire and

[2] Segal S, polishhuk WZ, Ben-David M. (1976) Hyperprolactinemic Male Infaertility.

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*Cellular and Molecular Neuroendocrine Research Laboratory, Department of Human Morphology, Semmelweis University,*

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**Chapter 9**

© 2013 Oner, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

© 2013 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,

distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

Prolactin (PRL) is one of several hormones that are produced by the pituitary gland. PRL has many different roles throughout the body, and most of those are clearly shown as clinical symptom. Perhaps the most important classical role of prolactin is to stimulate milk production in women after the delivery of a baby. Prolactin levels increase during pregnancy causing the mammary glands to enlarge in preparation for breastfeeding and ready to secrete colostrums closely after delivery. Later on the elevated prolactin levels help with the sustained production of milk during nursing. The somatomammotrop cells of the anterior pituitary gland synthesize and secrete prolactin, which is under the control of hypothalamic factors, mainly the tonic inhibition of Dopamine (DA). There are several other sources of PRL-like substances in the periphery such as placental lactogens, (similar to pituitary PRL), mammary gland (produced within the mammary epithelial cells), or PRL variants of immune cell origin (that modulates the immune system). (Gellersen,1989; Andersen 1990; Lkhider, 1996; Kurtz,1993; Gala, 1994, Montgomery,1990; Ben-Jonathan

It is important to underline that serum PRL in normal individuals is considered as almost entirely pituitary PRL sources, the above mentioned extra pituitary-PRL may contribute significant amounts but either carries as specific function and target mainly to the local

During the first several months of breastfeeding, the higher basal prolactin levels also serve to suppress ovarian cyclicity , through the inhibition of pituitary hormones, mainly via LH suppression (Taya 1982) This is the reason why women who are breastfeeding do not get their periods and therefore do not often become pregnant. In actively breastfeeding mothers the related hyperprolactinaemia persisting even over a year. It was observed that extended lactational amenorrhea is associated with low LH levels, and interestingly suckling induced PRL elevation as a response has a positive effect on prolongation. (Diaz 1991; Diaz 1995).

environment acting via paracrine/autocrine manner. (Yu-lee 1997; Bachelot 2007)

**Prolactin and Infertility**

Additional information is available at the end of the chapter

Gokalp Oner

http://dx.doi.org/10.5772/55557

**1. Introduction**

1996; Yu-Lee LY 1997)

#### **Chapter 9**


**4.3. Removal of micropollutants**

studied (lindane pesticides and diazinone), the rates of biosorption of these substances on

It can be assumed that in a system containing a mixture of several pollutants of a similar nature, the biosorption capacity of the individual components of the mixture will be affected by the concentration of the other substances in the mixture. A reduction in biosorbent capacity of tetrachloroethane on the *Rhizopus arrhizus* biomass has been shown to be up to 14% in the presence of the same concentration of trichloroethane [13]. Biosorption is usually an exothermic process, so biosorption capacity usually increases with decreasing temperature. However, the change in temperature does not significantly affect the rate of biosorption [8]. Simjonato et al. [9] studied the process of adsorption of blue remazol and black remazol five dyes with chitin and chitosan, which they performed in the column and an aqueous suspension. The results show that better results were obtained in the column with arthritis than in the chitin-packed column. Comparing the results measured in the column and suspension results in better suspension results. A very good description of Langmuir isothermal experimental values was obtained, with the difference between the measured and calculated adsorption

Biosorption of hazardous pollutants is a suitable technology for removing dyestuffs from municipal and industrial wastewater. Various low-cost biosorbents, such as, for example, biomass of algae, yeast, fungi, vegetable waste, fiber, fruit waste, chitosan, and agricultural

Biosorption and bioaccumulation can also be applied to remedy environments contaminated with heavy metals as complementary methods to currently used physical and chemical methods. It was found that removal of heavy metals from the environment with biotechnological methods should consider a number of physicochemical factors such as temperature, pH, contact time of biomass, and a solution containing metals, concentration and age of biomass, and toxicity when living microorganisms are applied. Improving the efficiency of removal of metals can be performed through physical and chemical modifications and immobilization of biomass. The most frequently applied reactors include stirred tank reactors, fixed-bed, reac-

In the process of biosorption, ions of metals are adsorbed on the surface of a sorbent. Biosorption is a metabolically passive process that uses dead biomass. Biosorption is the first

Environmental pollution of heavy metals is one of the most serious environmental problems. Various biosorbents such as fungi, yeast, bacteria, and algae are used to remove them. These biomaterials are considered to be cost-effective for high-volume and low-heavy wastewater treatment (from 1 to 100 mgl−1). The promising biomaterials for heavy metal removal include *Saccharomyces cerevisiae* fungus. This fungus is commonly used in food and beverage production. Low-cost media is sufficient to cultivate it. It is a by-product/waste from the fermentation

activated sludge were higher for higher concentrations of pollutants.

capacity values being insignificant.

waste were studied [48].

10 Biosorption

**4.2. Removal of heavy metals**

tors and fluidized-bed reactors [49].

step of bioaccumulation [49].

industry.

The large occurrence and presence of micropollutants (MPs) in the aquatic environment is one of the major challenges worldwide. For example, in 2012, some 143,000 compounds were registered on the European market, many of which at some point in their life cycle would end up in the aquatic environment. Most of them are not removed or transformed into conventional wastewater treatment plants (WWTPs), they can persist in the aquatic environment or create new chemicals by reaction with humic substances and sunlight, and they can be bioactive and can bioaccumulate [52–56].

Although present in almost undetectable (ppb; part per bilion) concentrations, their presence in the aquatic environment is associated with various deleterious effects in organisms such as estrogenicity, mutagenicity, and genotoxicity [57].

There is no legal regulation for removing MPs in WWTPs. However, there are some (EU) regulations that set limit values for certain substances that have specific MP properties, pesticides, lindane, nonylphenol, and synthetic hormones [58] in water.

MP can be divided into several categories such as pharmaceuticals personal care products (PPCP), household chemicals and industrial chemicals. A comprehensive list of 242 chemicals is included in the EU 7PP [59] project of which approximately 70% are pharmaceutical and personal care products, and 30% are industrial products, including perfluorinated compounds, pesticides, herbicides, and food additives.

to reducing the volume of aeration tank required and reducing investment costs, this bioreactor configuration is characterized by a high resistance to filamentous sludge bulking. The above mechanisms are also used as part of enhanced biological phosphorus removal processes [14–16]. In a hybrid system, slow and fast biodegradable substances and simultaneous macronutrient removal processes can be carried out by combined activated sludge and immobilized biomass [61]. Higher biomass concentrations and two different solid retention times significantly influence biosorption/bioaccumulation processes and ultimately, their participation in the

Introductory Chapter: Biosorption

13

http://dx.doi.org/10.5772/intechopen.78961

Biosorption and biodegradation also increase the efficiency of anaerobic sludge stabilization. Current research is mainly focused on increasing the efficiency of sludge stabilization. It is also focused on the research of anaerobic decomposition of micro-pollutants. However, there is little information and knowledge about biosorption potential and biosorption mechanisms of these substances. Information on pollutant biosorption on anaerobic sludge is important not only for the removal of pollutants themselves but also for the modeling of biological

Accumulation of dangerous hydrophobic organic pollutants, e.g. in activated sludge biosorption results in their removal from the wastewater stream, but the resulting disposal of contaminated sludge then poses a new environmental problem, especially when pollutants are bound to microbial sludge reversibly [33]. Reduction of sludge mass during stabilization leads to concentration of accumulated compounds, but potentially also to increase of their chemical activity as a result of reduction of sludge sorption capacity in the stabilization processes. This

However, such contamination remains a part of the activated sludge. Its release to the environment is dependent on further treatment with the excess sludge produced, especially if the

One of the current trends in the sludge management and the minimization of the release of priority substances and micro-nutrients through the application of the sludge in agriculture is the research of integrated biological and chemical processes to minimize the production of excess sludge and carry out the simultaneous transformation/degradation of micropollutants

The past decades brought intensive research leading to an understanding of biosorption processes with the aim of their application in water treatment technology t. Numerous papers were published that significantly contributed to a better characterization of complex phenomena involved in biosorption. Information was gathered on the bioprocess mechanisms and the influence of various factors in the removal of inorganic and organic pollutants by biosorption. In spite of targeted research on alternative low-cost sorption materials and extensive knowledge and publication results, it was not possible to apply this process practice in great extent, so far.

may lead to an increased risk related to compounds sorbed to the stabilized sludge.

whole complex of the biological wastewater treatment.

sludge stabilization systems [33].

biosorption of these substances is reversible.

sorbed on activated sludge [62–63].

**5. Conclusions**

The vast majority of MP in municipal wastewater belongs to the class of personal hygiene drugs and products PPCP, the fate and processes for removing these compounds are discussed in detail in this text.

About 70% of the wastewater products come from the household, 20% come from livestock, 5% come from hospital wastewater, and the remaining 5% come from outflows from nonspecified sources [60].

The removal of micropollutants in wastewater treatment plant depends on their solubility, octanol/water partition coefficient, and Henry's constant. For removing micropollutants in wastewater treatment plants significantly contributes their sorption on suspended particles of primary and secondary sludge. Removal of dissolved organic compounds also involves coagulation, flocculation and biodegradation processes. The majority of conventional wastewater treatment plants do not completely remove these substances. Their removal is influenced significantly by the operational conditions, the biochemical environment (aerobic, anaerobic, anoxic, sludge age (SRT), temperature, pH, and redox potential.

### **4.4. Biosorption in municipal wastewater treatment**

Biosorption and bioaccumulation mechanisms continue to play an important role in newly developed processes and technologies for wastewater treatment.

The fate of the priority substances and micropollutants that are transported by wastewater to wastewater treatment plants (WWTPs) depends on their adsorption on suspended particulates, dissolved humic substances, primary and secondary sludge. Adsorption of insoluble matter in primary and secondary treatment units is an important process of MP removal from wastewater. Adsorption may occur as a result of hydrophobic interactions between aliphatic and aromatic groups of lipid fractions in the primary sludge and the lipophilic cell membrane of the microorganisms in secondary sludge. Interactions also occur between positively charged MP groups and negatively charged microorganisms in secondary sludge.

#### *4.4.1. Integrated and hybrid processes*

Both the development of the activated sludge process and the increasing wastewater pollution are also developing biosorption applications. It is, for example, hybrid activated sludge process with activated carbon. Interaction of bio-degradation and adsorption on activated carbon benefits from the higher efficiency and performance of the process due to the concentration of organic matter on activated carbon, consequently higher rates of biological oxidation, as well as better conditions for the degradation of resistant substances, especially for industrial wastewater treatment and groundwater remediation.

In the 1950s of the last century, the activated sludge process with separate sludge regeneration was put into full-scale operation, where the ability to accumulate a substrate was restored. In addition to reducing the volume of aeration tank required and reducing investment costs, this bioreactor configuration is characterized by a high resistance to filamentous sludge bulking. The above mechanisms are also used as part of enhanced biological phosphorus removal processes [14–16].

In a hybrid system, slow and fast biodegradable substances and simultaneous macronutrient removal processes can be carried out by combined activated sludge and immobilized biomass [61]. Higher biomass concentrations and two different solid retention times significantly influence biosorption/bioaccumulation processes and ultimately, their participation in the whole complex of the biological wastewater treatment.

Biosorption and biodegradation also increase the efficiency of anaerobic sludge stabilization. Current research is mainly focused on increasing the efficiency of sludge stabilization. It is also focused on the research of anaerobic decomposition of micro-pollutants. However, there is little information and knowledge about biosorption potential and biosorption mechanisms of these substances. Information on pollutant biosorption on anaerobic sludge is important not only for the removal of pollutants themselves but also for the modeling of biological sludge stabilization systems [33].

Accumulation of dangerous hydrophobic organic pollutants, e.g. in activated sludge biosorption results in their removal from the wastewater stream, but the resulting disposal of contaminated sludge then poses a new environmental problem, especially when pollutants are bound to microbial sludge reversibly [33]. Reduction of sludge mass during stabilization leads to concentration of accumulated compounds, but potentially also to increase of their chemical activity as a result of reduction of sludge sorption capacity in the stabilization processes. This may lead to an increased risk related to compounds sorbed to the stabilized sludge.

However, such contamination remains a part of the activated sludge. Its release to the environment is dependent on further treatment with the excess sludge produced, especially if the biosorption of these substances is reversible.

One of the current trends in the sludge management and the minimization of the release of priority substances and micro-nutrients through the application of the sludge in agriculture is the research of integrated biological and chemical processes to minimize the production of excess sludge and carry out the simultaneous transformation/degradation of micropollutants sorbed on activated sludge [62–63].


**5. Conclusions**

This study employed remote sensing data and macro-scale hydrological modeling, and determined the role of past LCC in reshaping the future hydrological regime across the TNR of China. Land cover change may have imposed minor impacts on the hydrological regime over the past three decades. In contrast, it was found in this study that LCC may play a more significant role in altering ET and R in the future. The conclusions are as follows:

(4) Land cover changes in the TNR will play different roles in influencing ET and R. Specifically, LCC will likely slow the rate of increasing ET, while promoting increases in R, although the strength of these effects will vary across different basins. In the SRB, LRB, and HRB, the effects are much stronger than in other basins, and in the eastern four basins, R and SM will increase due to LCC, while decrease in the IRB. Additionally, the effects of LCC on ET, R, and SM will all increase over time, which means that the effects of LCC will increasingly strengthen in the future.

Compared to the hydrological effects over the past decades, the strengthening role of LCC on the future hydrological regime can be attributed to its long-term, cumulative effects and strengthening climate change (i.e., the rising temperature and increasing precipitation). However, the future hydrological regime in the TNR will be primarily driven by climate change. Based on the SM, the arid region (i.e., the IRB) may become drier and the humid regions (i.e., the east of the YRB and the south of the HRB) may become wetter, and these effects are consistent with the standard catchphrase, "dry gets drier, wet gets wetter" [39–41]. LCC may likely intensify these effects, implying dryland expansion in arid and semi-arid areas and a potentially increased flood risk in humid areas, although it may diminish ET so as to preserve water resources. Uncertainties may exist in our study, including the interactions among climate, water, and vegetation. Coupling land use and vegetation dynamics in the hydrological modeling can improve future hydrological projections.

**Author Contributions:** Conceptualization, Y.Y. and X.X.; methodology, Y.Y.; validation, X.X.; formal analysis, Y.Y.; investigation, Y.Y.; resources, Y.Y.; data curation, Y.Y., X.X., S.M., B.Z., K.Z. and Y.W.; writing—original draft preparation, Y.Y.; writing—review and editing, X.X.; visualization, Y.Y.; supervision, X.X.; project administration, X.X.; funding acquisition, X.X.

**Funding:** This research was funded by the National Natural Science Foundation of China (No. 41471019,<PHONE_NUMBER>6) and the National Key Research and Development Program of China (No. 2016YFC0401404). And The APC was funded by the National Natural Science Foundation of China (No. 41471019).

**Acknowledgments:** We would like to thank the three anonymous reviewers for their constructive comments and language editing.

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


*2.1. Preparation of CuCrO2 Hollow Nanotube*

Copper (II) acetate, chromium (III) acetate, and ethanolamine were dissolved in ethylene glycol monomethyl ether (30 mL) to obtain 0.2 M precursor. The prepared solution was stirred for 24 h to obtain a well-mixed solution without impurities. Al2O3 microfibers were dipped in Cu-Cr-O ion solution up to 3 sec to deposit Cu-Cr-O ions on the fiber surfaces and form an Al2O3-Cu-Cr-O core (Step 3). The Cu-Cr-O ions deposited on Al2O3 fibers were dried at 80 ◦C on a hotplate for 2 min. Then the coated fibers were annealed at 600 ◦C in vacuum (Step 4). After that, the prepared nanofibers were etched with 2 M H2SO4 to remove the Al2O3 and other minor impurities from the fibers (Step 5) [39]. The nanofibers were repeatedly rinsed with DI water and a centrifuge was used to separate the liquid and fibers. Finally, the collected nanofibers were dried in an oven at 80 ◦C to form CuCrO2 hollow nanotube (Figure 2).

**Figure 2.** Schematic illustration of CuCrO2 hollow nanotubes fabrication process.

#### *2.2. Characterization*

The crystallized phase of Al2O3 microfibers and CuCrO2 hollow nanotubes was characterized with an X-ray diffractometer (XRD, D2 Phaser, Bruker) with Cu Kα radiation (λ = 0.15418 nm) from 20◦ to 80◦, a working voltage of 30 kV, and current of 10 mA. The thermal decomposition behavior of the as-spun fibers was identified using a thermogravimetric analysis/differential scanning calorimeter (TGA/DSC, STA 449 F5, NETZSCH) at a heating rate of 10 ◦C/min. The surface morphology and structure of the nanofibers were observed by field emission scanning electron microscopy (FE-SEM, Hitachi S-4700) SEM 15 kV, 10 cm SEI detector, and nanotubes were identified by transmission electron microscopy (TEM, JEM-2100F, JEOL) operated at a working voltage of 200 kV, working current was10 μA and chamber was about 1.0 × 10−6 to 3.0 × 10−6 torr. The composition hollow nanotubes were confirmed by JOEL JEM2100F type scanning transmission electron microscope (STEM) attached with an energy dispersive spectrometer (EDS).

#### **3. Results**

#### *3.1. TGA Analysis*

The TGA/DSC analysis of the Al2O3 electrospun fibers studied at a heating rate of 10 ◦C/min in air is shown in Figure 3. Two discrete regions of electrospun fibers weight loss occurred at about 135 ◦C and 300 ◦C. The weight loss at around 135 ◦C could be attributed to DMF solvent. Exothermic peaks at 300 ◦C with a large weight loss of ~80% corresponded to the decomposition of nitrate, PVP polymer, and other minor organic constituents during the burning combustion. For temperature higher than 600 ◦C, there was almost no change in the TGA curve, which confirmed that the complete decomposition of organic materials and polymer during the formation of Al2O3 fibers [40–43].

**Figure 3.** Thermogravimetric-derivative thermal analysis of as-spun Al2O3 precursor microfibers recorded in air at a heating rate of 10 ◦C/min.

## *3.2. X-ray Di*ff*raction Investigation*

Figure 4 shows the XRD analysis of annealed Al2O3 fibers prepared by electrospinning method. The Al2O3 fibers were fabricated following the process mentioned in the last section with thermal annealing at elevated temperature for 2 h. We found no distinct diffraction peak for the as-spun fibers, but after the fibers were annealed at 600 ◦C, a clear amorphous phase was found. The XRD pattern indicated that the Al2O3 fibers became crystallized when the annealing temperature was over 800 ◦C [44].

Figure 5 shows the XRD pattern of Al2O3 fibers with copper chromium ions deposited on the surfaces after annealing in vacuum at 600 ◦C for 30 min and 60 min, and at 700 ◦C for 30 min. The fibers were composed of an Al2O3 core and the copper chromium ion solution. The XRD studies show the peaks of Al2O3 for the fibers annealed at 600 ◦C for 60 min. It is presumed that the prolonged annealing time caused the crystallization of alumina [39,44].

**Figure 4.** XRD patterns of electrospun Al2O3 precursor fibers annealed for 2 h in the air at various temperatures (600 ◦C–800 ◦C).

**Figure 5.** XRD patterns of Al2O3 microfibers with copper chromium oxide deposited on the surfaces after annealing at 600 ◦C and 700 ◦C in vacuum.

Figure 6 shows the XRD pattern of Al2O3 fibers with copper chromium ion solution deposited on the surfaces after annealing at 600 ◦C for 30 min in vacuum followed by leaching with 2M H2SO4 solution due to the strong acid and without the formation of impurities. That solution was employed because Al2O3 is an amphoteric oxide and reacts with both acid and alkaline solutions. From comparing Figure 6 with Figure 5, it is clear that the main phase of CuCrO2 can be clearly seen in the XRD pattern after the acid immersion. For comparison, NaOH solution was also used to remove alumina cores. As can be seen from the figures, after immersion of the fibers in NaOH solution, only the CuO phase remain while the chromium oxide disappeared. Therefore, we concluded that Al2O3 fibers with copper chromium ion solution deposited on the surfaces could be treated with 2M H2SO4 solution and DI water to obtain CuCrO2 hollow nanotube [39].

**Figure 6.** XRD patterns of Al2O3 microfibers with copper chromium oxide deposited on the surfaces after annealing at 600 ◦C in vacuum followed by leaching with 2M H2SO4 and NaOH solution.

#### *3.3. SEM Analysis*

The SEM micrographs of as-spun Al2O3 precursor fibers have fine cylindrical with smooth surface morphology and shows in Scheme 1 [41]. Besides, the SEM image of Al2O3 electrospun fibers annealed for 2 h in air at 600 ◦C and 800 ◦C are presented in Figure 7. The morphology of the fibers reveals that the Al2O3 fibers have continuous, one-dimensional structure and that the diameter of each Al2O3 fiber is <100 nm. The morphology and dimension of Al2O3 fibers are essentially similar in the case of annealing temperature of 600 ◦C and the counterpart in 800 ◦C.

**Figure 7.** SEM images of electrospun Al2O3 microfibers annealed for 2 h at (**a**) 600 ◦C and (**b**) 800 ◦C.

Figure 8 shows the morphology of Al2O3 fibers immersed in copper chromium ion solution and then dried for 2 min at 80 ◦C on a hotplate. After that, the Al2O3-CuCrO2 fibers were annealed in vacuum at 600 ◦C for 30 min (Figure 8a) and 60 min (Figure 8b), and at 700 ◦C for 30 min (Figure 8c). The surfaces of the fibers are smooth, and there is no specific change compared with calcined amorphous Al2O3 fibers. The copper chromium ion precursor solution, composed of mixed copper acetate, chromium acetate, and ethanolamine, was dissolved in ethylene glycol monomethyl ether.

Figure 9 shows a SEM image of Al2O3-CuCrO2 nanofibers after immersion in 2M H2SO4 and oven-drying at 80 ◦C for 1 day. As can be seen from the SEM morphology, there is a hollow-like structure at the tip of the CuCrO2 nanotubes etched by 2M H2SO4. It was inferred that the Al2O3 core was mostly removed by the H2SO4 solution and remaining impurities were removed by DI water.

**Figure 8.** SEM images of Al2O3-CuCrO2 nanofibers annealed at 600 ◦C for (**a**) 30 min, (**b**) 60 min, and at 700 ◦C for (**c**) 30 min.

**Figure 9.** SEM images of CuCrO2 hollow nanotubes after removal of Al2O3 core and impurities by 2M H2SO4 for 2 days and DI water.