In membrane protein biochemical and structural studies, detergents are used to mimic membrane environment and maintain functional, stable conformation of membrane proteins in the absence of lipid bilayers. However, detergent concentration, esp. molar ratio of membrane protein to detergent is usually unknown. Here, a gas chromatography-mass spectrometry selected ion monitoring (GC-MS-SIM) method...

A perfusion technique has been used to quantitate the effect of the amino acids glycine and alanine and the dipeptides glycyl-glycine and glycyl-L-alanine on sodium and water absorption from the human jejunum. Although no net absorption of sodium and water was seen in the absence of non-electrolytes, a significant stimulation occurred in the presence of both free amino acids and dipeptides. In ...

Replication of co-injected supercoiled DNA molecules in fertilized Xenopus eggs was monitored through the blastula stage of development. The extent of replication, as measured by 32P-dTMP incorporation into form I DNA, was directly proportional to the number of molecules, rather than the size, of the plasmid injected. Although only a small fraction of molecules of either template was replicated...

Biodiesel, known as fatty acid methyl ester (FAME), was produced from crude cottonseed oil (triglycerides) by transesterification with methanol in the presence of sodium hydroxide. This process was optimized by applying factorial design and response surface methodology (RSM) with SAS and PSIPLOT programs. A second-order mathematical model was obtained to predict the yield as a function of metha...

Electrochemical machining (ECM) has been increasingly recognized for the potential for machining, while the precision of the machined profile is a concern of its application. A process to erode a hole of hundreds of micrometers on the metal surface is analyzed in the current paper. A theoretical and computational model is presented to illustrate how the machined profile evolves as the time elap...

Response surface methodology (RSM) based on central composite rotatable design (CCRD) was used to optimize the three important reaction variables-methanol/oil molar ratio (M), NaOH catalyst concentration (C) and reaction time (T) for transesterification of crude cottonseed oil under ultrasonic irradiation. A quadratic polynomial model was obtained to predict the methyl ester yield. 98 wt% of th...

X-ray computed tomography (CT) images obtained with a polychromatic X-ray source were simulated by computer for homogeneous solutions and suspensions containing a heavy element. When the K-edge of the element was near the peak energy of the polychromatic X-ray spectrum, the degree of beam hardening in the simulated CT image strongly depended on the atomic number and molar concentration of the ...

Those bacteria that cause the reddening of salted hides and salted fish, commonly designated as halophiles, grow more luxuriantly in laboratory media as the salt concentration increases from about 3 molar to saturation. This stimulative effect of sodium chloride has been observed and reported by Clayton (^)/ Robertson (6), Lockhead (5), and Stuart and James (13), Halophilic bacteria also have b...

Presence of antibiotics in the environment may cause potential risk for aquatic environment and organisms. In this research, Fenton oxidation process was offered as an effective method for removal of antibiotic sulfamethoxazole from aqueous solutions. The experiments were performed on laboratory-scale study under complete mixing at 25±2°C. The effects of initial antibiotic concentration, molar ...

The ultrasound-assisted (UA) soybean oil methanolysis using KOH as a catalyst was studied at different reaction conditions in a microreactor. Box–Behnken experimental design, with three variables, was performed and the effects of three reaction variables i.e. reaction temperature, catalyst concentration and the methanol-to-oil molar ratio on fatty acid methyl ester (FAME) yield were evaluated b...