Subcritical water hydrolysis of N-acetyl-D-glucosamine: Hydrolysis mechanism, reaction pathways and optimization for selective production of 5-HMF and levulinic acid.

In this study, the subcritical water hydrolysis of N-acetyl-d-glucosamine (NAG), a monomer of abundant renewable marine biopolymer chitin, for production of value-added chemicals is investigated. The enhanced ionization of water at subcritical conditions (200 °C; 50-100 bar), provides enough acidity for deacetylation of NAG resulting in 80% yield of acetic acid along with traces of formic acid, lactic acid, glucose, fructose, 5-hydroxymethylfurfural (5-HMF),etc. The significant humin formation indicates that the self-condensation and polymerisation of 5-HMF is favored in water at subcritical conditions. A catalyst p-toluenesulfonic acid (p-TsOH) was employed to selectively convert NAG to levulinic acid (LA) via ring opening of 5-HMF previously formed during hydrolysis. The maximum yield of 27.13 ± 1% and 53.46 ± 1% of 5-HMF and LA, respectively, was obtained at process conditions optimized using Box-Behnken design coupled with response surface methodology. Subcritical water enables greener conversion of NAG to platform chemicals wherein the selective production can be achieved by tuning the process conditions.

Peripheral Arterial Injuries: an Indian Experience.

Arterial injuries present the most challenging conditions in surgical practice. Many fail to reach the specialist in time and end up losing limbs or lives. Though well addressed elsewhere, it has received less attention in developing countries like India. There is a need to study these injuries from the perspective of countries like India. The aims of the study are to (1) analyze the epidemiology, presentation, and outcomes of arterial injuries operated by the author in Indian settings; (2) identify factors associated with adverse outcomes; and (3) discuss the critical issues with relevance to our country. Retrospective analysis of arterial injuries operated by the author between July 2010 and February 2014 at our institution was performed. Patients with feasibility of revascularization were included and nonviable limbs requiring primary amputations were excluded. Sixty-one patients fulfilled the criteria of which 55 (90.1 %) were males and 6 (9.8 %) females aged between 5 and 70 years. The mean duration of presentation was 21 h. Majority were resultant of road traffic accidents (62.7 %). Among 49 (80.3 %) noniatrogenic injuries, the mechanism was blunt in 46 (93.8 %, n = 49) and penetrating in 3 (6.1 %) cases. Iatrogenic injuries were seen in 12 (19.6 %) cases. Lower limbs accounted for 37 (60.6 %) cases, popliteal segment being common, 22 (36 %) cases. Bony injuries were associated in 39 (63.9 %) cases. The most common procedure was interposition graft (49.1 %). Six (9.8 %) patients required an amputation resulting in 55 (90.1 %) salvaged limbs. Reaching a specialist center in appropriate time can result in good limb salvage rates and functional outcomes. Creating awareness and training the personnel are the critical issues in the management of arterial injuries in India.

Development of a reliable analytical method for the precise extractive spectrophotometric determination of osmium(VIII) with 2-nitrobenzaldehydethiocarbohydrazone: Analysis of alloys and real sample.

The proposed method demonstrates that the osmium(VIII) forms complex with 2-NBATCH from 0.8molL(-1) HCl at room temperature. The complex formed was extracted in 10mL of chloroform with a 5min equilibration time. The absorbance of the red colored complex was measured at 440nm against the reagent blank. The Beer's law was obeyed in the range of 5-25µgmL(-1), the optimum concentration range was 10-20µgmL(-1) of osmium(VIII) as evaluated by Ringbom's plot. Molar absorptivity and Sandell's sensitivity of osmium(VIII)-2NBATCH complex in chloroform is 8.94×10(3)Lmol(-1)cm(-1) and 0.021µgcm(-2), respectively. The composition of osmium(VIII)-2NBATCH complex was 1:2 investigated from Job's method of continuous variation, Mole ratio method and slope ratio method. The interference of diverse ions was studied and masking agents were used wherever necessary. The present method was successfully applied for determination of osmium(VIII) from binary, ternary and synthetic mixtures corresponding to alloys and real samples. The validity of the method was confirmed by finding the relative standard deviation for five determinations which was 0.29%.