Three‐Residue Turn in β‐Peptides Nucleated by a 12/10 Helix

A new three‐residue turn in β peptides nucleated by a 12/10‐mixed helix is presented. In this design, β peptides were derived from the 1:1 alternation of C‐linked carbo‐β‐amino acid ester [BocNH‐(R)‐β‐Caa_(r)‐OMe] (Boc=tert‐butyloxycarbonyl), which consisted of a D ‐ribo furanoside side chain, and β‐hGly residues. The hexapeptide with (R)‐β‐Caa_(r) at the N terminus showed the ‘turn’ stabilized by a 14‐membered NH(4) ??? CO(6) hydrogen bond at the C terminus nucleated by a robust 12/10‐mixed helix, thus providing a ‘helix‐turn’ (HT) motif. The turn and the helix were additionally stabilized by intraresidue electrostatic interaction between the furan oxygen in the carbohydrate side chain and NH in the backbone. However, the hexapeptide with a β‐hGly residue at the N terminus demonstrated the presence of a 10/12 helix through its entire length, which again showed the intraresidue interaction between NH and furan oxygen. The intraresidue NH ??? O? Me electrostatic interactions observed in the monomer, however, were absent in the peptides.     

Permeabilization of Kluyveromyces marxianus with Mild Detergent for Whey Lactose Hydrolysis and Augmentation of Mixed Culture

Cheese whey is a by-product of cheese-manufacturing industries, and the utilization of whey is a challenging problem either to use it or dispose it, because only few microorganisms can metabolize the whey lactose. Enzymatic hydrolysis of whey lactose to glucose and galactose by β-galactosidase is the approach for biotechnological application. Kluyveromyces marxianus cells were permeabilized with non-toxic, biodegradable, anionic detergent N-lauroyl sarcosine (N-LS) for the enzyme activity. The permeabilization process parameters (N-LS concentration, solvent volume, temperature and incubation time) were optimized. The maximum β-galactosidase activity of 1,220 IU/g dry weight was obtained using permeabilized cells under optimized conditions. Moreover, viability of the permeabilized cells was also evaluated, which showed that cells were alive; however, viability was reduced by two log cycles. The permeabilized cells were evaluated for whey lactose hydrolysis. The maximum lactose hydrolysis of 91 % was observed with 600 mg (dry cell weight/100 mL) in whey powder (5 % w/v) solution at 180-min incubation, pH 6.5 and 30 °C. Further, the hydrolyzed whey was evaluated for amelioration of growth of non-lactose-consuming yeast Saccharomyces cerevisiae. S. cerevisiae was able to grow in hydrolyzed whey simultaneously with K. marxianus. The study confirmed that N-LS could be used to permeabilize K. marxianus cells to make available the enzyme activity.     

Uranium in groundwater from Western Haryana,India

This study was undertaken to assess uranium in groundwater and radiological and chemical risks associated with its ingestion in rural habitats in the vicinity of proposed nuclear power project in Western Haryana, India. Uranium concentration in the groundwater of the study area varied from 0.3 to 256.4 μg L^?1. Radiological risk calculated in the form of average life time dose was found 5.1 × 10^?2 mSv to the residents of the area from the ingestion of groundwater. The average cancer mortality and average cancer morbidity risk were calculated to be 4.9 × 10^?6 and 7.7 × 10^?6 respectively indicating the absence of carcinogenic risks. Chemical risk was in the range of 0.02–18.8 µg kg^?1 day^?1. Hazard quotient for 72 % samples was greater than unity which indicates health risk due to chemical toxicity of uranium in groundwater. The results indicate that uranium concentrations in the groundwater of the study area are important due to chemical risk than radiological risk.     

Experimental and theoretical investigation on adsorption and corrosion inhibition properties of imidazopyridine derivatives on mild steel in hydrochloric acid solution

Imidazopyridine derivatives, namely 4‐methoxy‐N‐((2‐(4‐methoxyphenyl)H‐imidazo[1,2‐a]pyridin‐3‐yl)methylene)benzenamine (MMPIPB) and 4‐chloro‐N‐((2‐(4‐methoxyphenyl)H‐imidazo[1,2‐a]pyridin‐3yl)methylene)benzenamine (CMPIPB), were investigated as inhibitors for mild steel corrosion in 15% HCl solution using the weight loss and electrochemical techniques. According to electrochemical impedance spectroscopy studies, MMPIPB and CMPIPB show corrosion inhibition efficiency of 84.8 and 77.2% at 10‐ppm concentration and 98.1 and 94.8% at 80‐ppm concentration, respectively at 303 K. The corrosion inhibition efficiency of both inhibitors increased with increasing inhibitor concentration and decreased with increasing temperature. The adsorption of both inhibitor molecules on the surface of mild steel obeys Langmuir adsorption isotherm. Polarization studies showed that both studied inhibitors were of mixed type in nature. Electrochemical impedance spectroscopy studies showed that for both inhibitors, the value of charge transfer resistance increased and double‐layer capacitance decreased on increasing the concentration of inhibitors. Scanning electron microscopy, energy‐dispersive X‐ray spectroscopy (EDX), and atomic force microscopy were performed for surface study. The density functional theory was employed for theoretical calculations. Copyright © 2014 John Wiley & Sons, Ltd.     

Determination of total gas content and its composition in Indian PFBR blanket pellets

Total gas content and its composition are important specifications for sintered nuclear fuel pellets particularly in the case of fast breeder reactor fuels. Most commonly, total gas content and its composition is determined by hot vacuum extraction-quadrupole mass spectrometry (HVE-QMS). A number of parameters in this methodology such as temperature, duration of heating for quantitative extraction of evolved gases, total volume of the system, gas analysis conditions etc. need to be optimized for reliable measurements. In addition, sensitivity factors for various gases like H₂, CH₄, N₂, CO, O₂ and CO₂ in quadrupole mass spectrometry required for quantification of results have been determined and validated employing reference gas mixtures of known composition. Employing these optimized conditions total gas content and its composition in blanket pellets (uranium oxide pellets) of Indian prototype fast breeder reactor was determined employing HVE-QMS. The relative expanded uncertainty (at a coverage factor k = 2) in the measurement of total gas content excluding hydrogen was estimated as per ISO guidelines and it was found to be 9.2 %.     

Study of 10Be in the sediments from the Krossfjorden and Kongsfjorden Fjord System,Svalbard

The distribution of ¹⁰Be, as well as the major elements concentrations and the grain size in surface and core sediment samples, collected from Krossfjorden and Kongsfjorden, Svalbard have been studied for understanding the origin of ¹⁰Be and an estimation of its accumulation rate. The ¹⁰Be concentration in sediments varies between 0.90 × 10⁸ and 2.53 × 10⁸ atoms g^?1. Our results show that atmospherically produced ¹⁰Be dominates over terrigenous (in situ) sources of ¹⁰Be in the studied samples. The calculated ¹⁰Be accumulation rate varies from 3.1 × 10⁶ atoms cm^?2 year^?1 to 8.6 × 10⁶ atoms cm^?2 year^?1 which is higher than the accumulation rate observed in the deep sea sediment cores of the Arctic Ocean and the Norwegian Sea. The higher accumulation rate of ¹⁰Be is attributed to the higher influx of glacier melt water into the fjord system.     

Metal-Free,One-Pot Oxidative Conversion of Aldehydes to Primary Thioamides in Aqueous Media

One-pot tandem reactions of a variety of aldehydes with aqueous ammonia, molecular iodine, and O,O-diethyl dithiophosphoric acid readily afford the corresponding primary thioamides. This is an inexpensive, practical, and metal-free way of accessing various thioamides from aldehydes in aqueous media. The pure products are obtained simply by filtration followed by successive washing with aqueous sodium thiosulfate and water.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Stereoselective synthesis of C19–C27 fragment of bryostatin 11

A convergent synthesis of C19–C27 fragment (2) of bryostatin-11 is described. The key steps involved in this approach are kinetic resolution, Grignard reaction, and Sharpless dihydroxylation. AIBN catalyzed radical cyclization strategy has been used for the first time to construct the six-membered pyran system.