Total and acylated ghrelin levels in children and adolescents with idiopathic short stature and poor appetite

Context. Ghrelin is a hormone secreted primarily from stomach that can affect growth by its somatotropic and orexigenic activities. Objective. The aim of this study was to investigate the relationship of ghrelin and growth in children and adolescents with idiopathic short stature. Subjects and Methods. After thorough clinical examination, 56 subjects including 31 with normal weight and height and 25 with short stature were evaluated for fasting total (TG) and acylated (active) ghrelin (AG) levels. All the parameters of growth including growth hormone and IGF-1 levels, bone age and body mass index were also investigated. Appetite was also assessed and all the studied subjects were also divided into two groups, poor or good appetite. Results. TG and AG levels were not significantly different in the two groups. There was not any significant correlation between ghrelin and parameters of growth. On the other hand, TG concentration was significantly higher in subjects with poor appetite, but AG was not significantly different. Conclusions. The results of this study show that ghrelin is not significantly altered in idiopathic short stature. Although TG is increased in children with poor appetite its acylation is not increased concomitantly. © 2015, Editura Academiei Romane. All rights reserved

Synthesis and application of polypyrrole/carrageenan nano-bio composite as a cathode catalyst in microbial fuel cells

A novel nano-bio composite polypyrrole (PPy)/kappa-carrageenan(KC) was fabricated and characterized for application as a cathode catalyst in a microbial fuel cell (MFC). High resolution SEM and TEM verified the bud-like shape and uniform distribution of the PPy in the KC matrix. X-ray diffraction (XRD) has approved the amorphous structure of the PPy/KC as well. The PPy/KC nano-bio composites were then studied as an electrode material, due to their oxygen reduction reaction (ORR) ability as the cathode catalyst in the MFC and the results were compared with platinum (Pt) as the most common cathode catalyst. The produced power density of the PPy/KC was 72.1 mW/m2 while it was 46.8 mW/m2 and 28.8 mW/m2 for KC and PPy individually. The efficiency of the PPy/KC electrode system is slightly lower than a Pt electrode (79.9 mW/m2) but due to the high cost of Pt electrodes, the PPy/KC electrode system has potential to be an alternative electrode system for MFCs

Electerochemical study of sulfonated poly ether ether ketone nanocomposite membrane for direct methanol fuel cell application

High methanol permeability and expensive price of current commercial Nafion® membrane for direct methanol fuel cell (DMFC) have encouraged researchers to modify proton exchange membrane (PEM). Sulfonted poly ether ether ketone (SPEEK) is a polymer which attracted a lot of attention recently. This study aimed to test the DMFC performance of nanocomposite SPEEK membrane filled with Cloisite 15A® clay by introducing 2,4,6 triaminopyrimidine (TAP) as a compatibilizer as electrolyte membrane at room temperature to 80oC and compare with Nafion 117. SPEEK polymer was made at 60oC in order to obtain the degree of sulfonation of 60%. According to the results, the SPEEK nanocomposite with the following composition SP60/CL2.5/TAP5.0 showed higher proton conductivity and methanol permeability than of Nafion 117 at various temperatures because of the presence of CL and TAP addition.Furthemore the highest overall performance( membrane selectivity) was allocated to the SP60/CL2.5/TAP5.0 at 60oC while the lowest one was for Nafion 117 at 80oC. In addition DMFC performance results showed the OCV for the nanocomposite membrane increase when the temperature increase. In addition voltage and power density increase with temperature incerement due to catalyst high activity on electrode surface,and higher proton conductivity , clearly the maximum power density at 60oC was 54.93 (mWcm-2)

Water Absorption and Thickness Swelling behavior of Medium Density Fiberboard Manufactured by Hydrothermally Treated Fibers

In this research, water absorption and thickness swelling behavior of hydrothermally modified fiberboard (MDF). Were evaluated Fibers were treated in a stainless steel reactor at temperatures of 120, 150 and 180°C for holding times of 0, 30 and 90 min. Test boards were prepared based on the target density of 0.7g/cm3 at the press temperature of 175°C as well as the pressure of 30 bar and the press time of 5 min. Urea formaldehyde (UF) resin was applied at 10% based on the fibers dry weight. Test samples (10×20×20mm) were cut from the boards, dried in an oven and soaked in the water. Water absorption, thickness swelling and their rates were measured in the soaked samples. Results revealed that increase of the treatment temperature caused decrease of water absorption and thickness swelling in the treated boards except in samples treated at 120°C. It was also indicated that increase of the holding time did not significantly affect water absorption and thickness swelling

Effects of montmorillonite (MMT) on morphological, tensile, physical barrier properties and biodegradability of polylactic acid/starch/MMT nanocomposites

Biodegradable polymer nanocomposites have received great attention due to their synergistic properties of good mechanical and barrier properties; yet, they are biodegradable. In this research, prior to compression into thin sheets, polylactic acid (PLA), tapioca starch, glycerol and maleic anhydride (MA) were compounded with different loadings of montmorillonite (MMT) through a twin screw extruder. MMT was added to improve the mechanical and barrier properties of PLA/starch blend. The effects of MMT loadings on tensile property, morphology and biodegradability were studied. X-Ray diffraction analysis showed that samples with MMT loadings below 6 phr exhibited exfoliated structure, while samples that contained MMT above 6 phr (5.66 wt%) exhibited intercalated structure. The exfoliated-type structure was observed using transmission electron microscopy. These effects were manifested in the tensile results, which showed an increase in modulus, tensile strength and elongation at break. However, for the modulus, the MMT content was limited to 4 phr (3.85 wt%). Beyond that, the modulus decreased. It was thought that above 4 phr, the MMT particles agglomerated, thus reducing the modulus of the samples. This argument was supported by field emission scanning electron microscopic images, which showed big lump when MMT loadings were at 6 and 8 phr (7.41 wt%). Meanwhile, the addition of MMT has improved the water barrier property and hastened the rate of biodegradation. The nanosized MMT particles disturb the continuity of PLA/starch chain, which formed pathways for microorganisms to enter and attack the chain, thus increasing the biodegradation rate. The particle is also able to block a tortuous pathway for water to enter the starch chain, thus reducing the water uptake and improving the physical barrier of nanocomposite

Review on the development of fuel cells and its future prospects

Fossil fuels are unsustainable energy storage medium with pollution problems. With the limitation of fossil fuels, fuel cells, which are known as effective electrochemical converters, has attracted much attention. Present review paper provides a complete information on fuel cell technology and history which includes competing technologies, current status of research-and-development and its future direction. Fuel cell plays an important role in stationary applications from 1990s till now due to its efficiency upon reducing emissions