Role of Zinc (Zn) in Human Reproduction: A Journey from Initial Spermatogenesis to Childbirth

Zinc (Zn), the second-most necessary trace element, is abundant in the human body. The human body lacks the capacity to store Zn; hence, the dietary intake of Zn is essential for various functions and metabolism. The uptake of Zn during its transport through the body is important for proper development of the three major accessory sex glands: the testis, epididymis, and prostate. It plays key roles in the initial stages of germ cell development and spermatogenesis, sperm cell development and maturation, ejaculation, liquefaction, the binding of spermatozoa and prostasomes, capacitation, and fertilization. The prostate releases more Zn into the seminal plasma during ejaculation, and it plays a significant role in sperm release and motility. During the maternal, labor, perinatal, and neonatal periods, the part of Zn is vital. The average dietary intake of Zn is in the range of 8–12 mg/day in developing countries during the maternal period. Globally, the dietary intake of Zn varies for pregnant and lactating mothers, but the average Zn intake is in the range of 9.6–11.2 mg/day. The absence of Zn and the consequences of this have been discussed using critical evidence. The events and functions of Zn related to successful fertilization have been summarized in detail. Briefly, our current review emphasizes the role of Zn at each stage of human reproduction, from the spermatogenesis process to childbirth. The role of Zn and its supplementation in in vitro fertilization (IVF) opens opportunities for future studies on reproductive biology.     

Close-range blast loading on empty recyclable metal beverage cans for use in sacrificial cladding structure

This article deals with the experimental and numerical blast study on a single empty recyclable metal beverage can. The idea is to make a macro-foam (sacrificial cladding structure) out of these cans to protect the main load bearing members of civil engineering structures from the air blast load. Close-range free air blast tests have been conducted to understand the crushing behaviour and the energy absorption of a single empty beverage can in detail. To conduct such an air blast test a special small-scale test set-up was designed and manufactured. The effect of skin plate surface area and its nature on the blast parameters is studied. Furthermore, the effect of inertia of the skin plate on the crushing performance of the beverage can is evaluated. Tests have been conducted with different plates (made of aluminium and sandwich composite materials) with different masses which represent the skin plate of the proposed sacrificial structure. The measured blast parameters from the experimental tests were compared with ConWep predicted data. Furthermore, the influence of the finite surface area of the skin plate on the clearing of the reflected pressure waves was also studied. The deformation behaviour and the corresponding energy absorption of empty beverage cans were captured. During the experimental blast tests it was observed that a part of the total reflected impulse (∼30%) was lost before it transfers to the non-sacrificial structure. Hence, in order to investigate this phenomenon Eulerian-Lagrangian coupled analyses were conducted using Hydrocodes. The results from these analyses showed that the diffraction and ground reflected pressure wave caused the loss in impulse. The results from the numerical studies have been compared and validated with the experimental results.     

Synergistic effect of silane modified nanocomposites for active corrosion protection

This work presents an effective anticorrosion behavior of a hydrophobic surface on stainless steel 304. The protective coating has been designed by dispersing nanocomposites (cloisite 15A, multiwalled carbon nanotubes and cerium chloride) which act as a corrosion inhibitor. The sol was prepared by using 3-glycidoxypropyltrimethoxysilane (GPTMS), octyltriethoxysilane (OTES) and zirconium (IV) butoxide as precursors. The corrosion resistance of coated stainless steel got improved when nanocomposites were homogeneously embedded in silica sol. The influence of nano-particles on the barrier coatings impedes corrosion. The coatings were analyzed by X-ray diffraction (XRD) to ensure the intercalation and distribution of nanocomposites in layered silicates. Fourier transform infrared spectroscopy (FTIR) was employed to characterize the nanocomposites modified silica sol. Scanning electron microscopy (SEM) was used to examine the morphology of the modified silane coating. The contact angle measurements ensured the hydrophobic behavior of the coatings. The corrosion behavior was investigated using Electrochemical Impedance Spectroscopy (EIS). This study has led to a better understanding of active anticorrosive coatings with embedded nanocomposites and the factors influencing the anticorrosion performance.     

Studies on Silicon Containing Nano-hybrid Epoxy Coatings for the Protection of Corrosion and Bio-Fouling on Mild Steel

An epoxy nano-composite coating was developed using amine functionalized nZnO (in the amount of 2.5 %, 5.0 % and 7.5 wt %) as the dispersed phase and a commercially available epoxy resin as the matrix phase. The structural features of these materials were ascertained by FT-IR spectral studies. The anti-corrosive properties of the epoxy/nZnO hybrid coatings in comparison with a virgin coating were investigated by a salt spray test and electrochemical impedance spectroscopy technique. The surface morphology determined by SEM, indicates that nZnO particles were dispersed homogenously through the epoxy polymer matrix. The results showed improved antifouling and anticorrosive properties for epoxy-nZnO hybrid coatings.     

Removal of nickel(II) ions from aqueous solution using crab shell particles in a packed bed up-flow column

This paper investigates the ability of crab shell to remove nickel(II) ions from aqueous solution in a packed bed up-flow column with an internal diameter of 2 cm. The experiments were performed with different bed heights (15-25 cm) and using different flow rates (5-20 ml/min) in order to obtain experimental breakthrough curves. The bed depth service time (BDST) model was used to analyze the experimental data and the model parameters were evaluated. The column regeneration studies were carried out for seven sorption-desorption cycles. The elutant used for the regeneration of the sorbent was 0.01 M EDTA (disodium) solution at pH 9.8 adjusted using NH4OH. Due to continuous usage of crab shell, a performance loss was observed as the breakthrough curves become more flattened also indicated by the broadened mass transfer zone. The breakthrough time decreased uniformly from 28.1 to 9.5 h as the cycles progressed from one to seven, whereas nickel uptake remained approximately constant throughout the seven cycles. The life-factors for crab shell in terms of critical bed length and breakthrough time were found to be 1.1 cm/cycle and 0.17 per cycle, respectively. The elution efficiency was greater than 99.1% in all the seven cycles. The pH profiles during both sorption and desorption process were also reported. In sorption cycles, there was a sudden raise in pH in the early part of the process and then the pH decreased as the time progressed. In desorption cycles, pH decreased in initial stages and followed by gradual increase in pH, which eventually reached the pH of the inlet elutant.     

A strategy to reduce the control packet load of MANETs with bidirectional links using DSR

Dynamic source routing (DSR) is a robust protocol commonly applied to multi‐hop wireless mobile ad hoc networks (MANETs). In this paper, an algorithm is proposed for modifying the basic DSR protocol to enhance its performance by reducing the number of redundant route reply packets (RREPs). In the modified DSR (MDSR), for a source destination pair, the destination responds to the first received route request packet (RREQ) with an RREP, and the subsequently received RREQs, bearing the same request ID, are responded to only if the hop count is less than that of all the previously received RREQs. The performance of MDSR has been compared with that of the basic DSR for different network densities and for different mobility of nodes. Simulation results show that MDSR gives fewer control packets, less latency and a higher packet delivery ratio than DSR. Copyright © 2007 John Wiley & Sons, Ltd.     

Carbon capture and storage using coal fly ash with flue gas

Clean Technologies and Environmental Policy - Rising CO2 emissions call for actions to urgently address climate change and its impacts. To avoid the harmful consequences of climate change, limiting...     

Anti-corrosion coatings on SS 304 by incorporation of Pr6O11–TiO2 in siloxane network

This paper describes an attempt to develop anticorrosive siloxane coatings based on Pr₆O₁₁–TiO₂ composite films for SS 304 substrate by sol-gel technique. We demonstrate for the use of praseodymium oxide doped Titanium oxide (Pr₆O₁₁–TiO₂) nanocomposites loaded in a hybrid sol-gel layer, to effectively protect the underlying steel substrate from corrosion attack. The influence of Pr₆O₁₁–TiO₂ gives the surprising aspects based on active anti-corrosion coatings. The silica sol was treated with Pr₆O₁₁–TiO₂ to achieve different level of add-on i.e.) 0–1 wt % of nanocomposites. The influence of different weight percent of nanocomposites on silica matrix for anticorrosion performance was investigated by Electrochemical Impedance Spectroscopy (EIS). Pr₆O₁₁–TiO₂ nanocomposites loaded in a hybrid sol-gel layer effectively protect the underlying substrate from corrosion attack. The results showed significant improvement in anticorrosion property for higher add-ons up to the optimized percent of nanocomposites. Furthermore, Transmission Electron Microscopy (TEM) and Scanning Electron Microscope Microscopy (SEM) were used to characterize the surface morphology of doped and undoped coatings. The studied showed a synergistic effect between Pr₆O₁₁–TiO₂ and siloxane matrix has leads to a self-healing coatings.