Location of a membrane-bound carbonic anhydrase isoenzyme (CA IV) in the human male reproductive tract

We studied the location of a membrane-bound carbonic anhydrase (CA IV) in the human male reproductive tract using a specific antiserum to human CA IV in conjunction with immunoblotting, immunoperoxidase, and immunofluorescence techniques. The microvilli and apical plasma membrane of the epithelial cells and the subepithelial smooth muscle layer of the epididymis, ductus deferens, and ampulla of the ductus deferens showed specific staining for CA IV. The epithelial cells of the prostate and seminal vesicle failed to stain for CA IV, however, whereas the subepithelial smooth muscle layer showed positive staining. No specific staining for CA II was seen in the epithelium of the epididymal duct or the proximal ductus deferens. The presence of CA IV in the epididymis was confirmed by immunoblotting, which revealed 35 KD and 33 KD polypeptides. The results show that the microvilli and the apical plasma membrane of the lining epithelium of the epididymal duct, ductus deferens, and ampulla of the ductus deferens contain the membrane-bound carbonic anhydrase isoenzyme IV. The presence of the enzyme in the epithelium of the epididymis and ductus deferens is probably linked to the acidification of the epididymal fluid that prevents premature sperm activation. Its physiological role in the smooth muscle cells remains to be elucidated.     

Performance of a Nongasketed Flange Joint under Combined Internal Pressure and Bending Loading

Performance of a bolted flange joint is characterized mainly due to its “strength” and “sealing capability.” A number of analytical and experimental studies have been conducted to study these characteristics only under internal pressure loading. A very limited amount of work is found in the literature under combined internal pressure and bending loading. Due to the ignorance of this external loading, i.e., bending loading, the optimized performance of the bolted flange joint cannot be achieved. The present design codes do not address the effects of bending loading on the structural integrity and sealing ability. To investigate joint strength and sealing capability under combined loading, an extensive comparative experimental and numerical study of a nongasketed flange joint is carried out and overall joint performance and behavior is discussed. Actual joint load capacity is determined under both the design and proof test pressure with maximum additional external bending loading that can be applied for safe joint performance. In addition, as experimentally it is impossible to test different flange joint sizes under combined loading application, hence finite element model developed and verified with the experimental results, presented in this paper can be used as base to study the behavior for different nongasketed flange joint sizes for different classes under combined pressure and bending loading.     

A chemometric approach for the quantification of free fatty acids in cottonseed oil by Fourier transform infrared spectroscopy

The aim of this study was to quantify free fatty acid in cottonseed oil (Gossypium) variety by a chemometric approach using Fourier transform infrared spectroscopy. Calibration standards were prepared by gravimetrical mixing of oleic acid (0.1–40 g/100 g) in neutralized cottonseed oil containing <0.1% free fatty acids. Fourier transform infrared technique coupled with partial least square and principle component regression models were used to develop calibrations in the specific absorption region of carbonyl between 1690–1727 cm^?1. On the basis of regression coefficient and evaluated free fatty acids results with comparison to titration method, partial least square was found to be more accurate than principle component regression calibration model. All the analyzed cottonseed oil varieties showed high content of free fatty acids in the range of 17.1–38.5%. The results of the present study indicated that Fourier transform infrared method in combination with partial least square or principle component regression could be used as a greener alternative to the standard titration method.     

Recent advances and perspectives on starch nanocomposites for packaging applications

Starch nanocomposites are popular and abundant materials in packaging sectors. The aim of this work is to review some of the most popular starch nanocomposite systems that have been used nowadays. Due to a wide range of applicable reinforcements, nanocomposite systems are investigated based on nanofiller type such as nanoclays, polysaccharides and carbonaceous nanofillers. Furthermore, the structures of starch and material preparation methods for their nanocomposites are also mentioned in this review. It is clearly presented that mechanical, thermal and barrier properties of plasticised starch can be improved with well-dispersed nanofillers in starch nanocomposites.     

Parametric study of pyrolysis and steam gasification of rice straw in presence of K<Subscript>2</Subscript>CO<Subscript>3</Subscript>

A parametric study of pyrolysis and steam gasification of rice straw (RS) was performed to investigate the effect of the presence of K₂CO₃ on the behavior of gas evolution, gas component distribution, pyrolysis/gasification reactivity, the quality and volume of synthetic gas. During pyrolysis, with the increase in K₂CO₃ content in RS (i) the instantaneous CO₂ concentration was increased while CO concentration was relatively stable; (ii) the yield of CO₂ and H₂ increased on the cost of CH₄. During steam gasification of RS, with the increase in K₂CO₃ content in RS (i) the instantaneous concentration of CO₂ and H₂ increased while instantaneous concentration of CO and CH₄ decreased; (ii) the yield of CO₂ and H₂ production and total yield increased; and (iii) yield of CO and CH₄ production followed the order: 9% K₂CO₃ RS<6% K₂CO₃ RS<raw RS<3% K₂CO₃ RS<water-leached RS. Water-leached RS showed the highest pyrolysis reactivity, while stream gasification reactivity was proportional to K₂CO₃ content in RS. The results of this study reveal that the presence of K₂CO₃ during pyrolysis and steam gasification of RS effectively improves production of H₂ rich gas.     

Environmentally safe corrosion inhibition of the Cu–Ni alloys in acidic sulfate solutions

The corrosion and passivation behaviors of alloys with different Cu–Ni ratios were investigated in acidic sulfate solutions. The corrosion rate was calculated and the corrosion inhibition process was investigated using different amino acids as corrosion inhibitors. For these investigations conventional electrochemical techniques and electrochemical impedance spectroscopy (EIS) were used. Fitting of the experimental impedance data to theoretical values enables understanding of the corrosion inhibition mechanism and the suggestion of a suitable electrical model to explain the behavior of the alloys under different conditions. The investigation of the electrochemical behavior of alloys before and after the corrosion inhibition processes has shown that some amino acids like lysine have promising corrosion inhibition efficiency at very low concentrations. A model for the electrode/electrolyte interface during the corrosion inhibition processes was suggested and the validity of the model for the explanation of the corrosion inhibition phenomena was discussed.     

Size Distribution and Sources of Trace Metals in Ultrafine/Fine/Coarse Airborne Particles in the Atmosphere of Shanghai

Airborne particulate matter (PM) samples in 13 different size-fractions from 0.0283 to 9.92 μm were collected in winter of 2007 at three sites in Shanghai, China. The PM exhibited a bimodal distribution with a major mode in the fine particle size range (D_p = 0.2–1 μm) and a minor mode in the coarse range (D_p = 1–10 μm), suggesting that fine particle pollution is dominant in the Shanghai atmosphere. Trace metals in PM exhibited the following distribution patterns: (1) unimodal distribution in the fine fraction (Pb, Cd, Se, Sn, Bi, and Zn), (2) unimodal distribution in the coarse fraction (Mg, Al, Fe, Ca, Ba, Sr, Ge, Zr, U, and rare earth elements), (3) bimodal distribution, with one mode in the fine fraction and one in the coarse fraction (Cu, Mn, K, Ga, V, Rb, and Cs), and (4) multimodal distribution (Na, Ti, Cr, Co, As, Ni, Mo, Ag, W, Pt, Au, S, and Cl) throughout the entire aerosol size spectrum. In addition to these size distributions, Aitken modes due to local origins were also evident for Se, Sn, Cu, V, Ti, Cr, Co, As, Ag, Mo, and Pt, whose respective mass in the ultrafine particles (<0.1 μm) was 10, 23, 13, 19, 23, 14, 67, 32, 79, 40, and 21%, with submicron mass median aerodynamic diameters (MMADs) in PM_0.02-9.92 (except Pt). In particular, the MMADs for Co and Ag were <0.1 μm, which increase potential health issues. The measured distributions are believed to result from a combination of processes including local anthropogenic and natural sources, such as traffic, coal combustion, and the steel industry.