Spectrophotometric determination of zinc in copper-base alloys with TAN

TAN reacts with zinc(II) forming a red complex with composition 1:2 Zn(II)-TAN and absorption maximum at 582 nm. Zinc can be determined with this reagent in the presence of Triton X-100, in the pH range 6.20-8.00 with a molar absorptivity of 4.5×10⁴ l/mol/cm Beer's Law was obeyed up to least 1.55 g/ml. Copper interference was eliminated with a mixture of thiosulfate and ascorbic acid and nickel separated by precipitation with dimethylglyoxime. The proposed method was used for zinc determination in several copper-base alloys and the results of analysis in comparison with certified values indicated that the procedure was accurate and precise. A derivative procedure is also proposed, allowing zinc determination with high sensitivity (5-400 ng/ml).     

Development and validation of SPMMTE HPLC method for analysis of profens from human plasma

A fast, selective and reproducible solid‐phase membrane microtip extraction (SPMMTE) HPLC method has been developed and validated for the analyses of ibuprofen, ketoprofen, and flurbiprofen from human plasma. The analysis was carried out on a C₁₈ (150 × 4.6 mm; 5 μm) column. The mobile phase used was water–acetonitrile (55:45, v/v) adjusted to pH 3.0 using trifluoroacetic acid, at a flow rate 0.5 mL/min with a detection wavelength of 225 nm. The values for the capacity factors for the profen samples ranged from 0.47 to 1.50. The values for the selectivity factor (α) for ketoprofen–flurbiprofen, flurbiprofen–ibuprofen and ibuprofen–ketoprofen combinations from human plasma samples were 1.99, 1.00 and 2.10, respectively. The resolution factors (Rs) for ketoprofen–flurbiprofen, flurbiprofen–ibuprofen and ibuprofen–ketoprofen from plasma samples were 3.00, 1.50 and 4.10, respectively. The percentage recoveries of ibuprofen, ketoprofen, and flurbiprofen from human plasma were 75–85%. All of the profens were separated within 7.0 min, indicating a relatively fast method. During the development of the SPMMTE procedure the parameters of pH, contact time, desorption and types of solvents were optimized. The final method was also found to be efficient, effective and inexpensive. Copyright © 2016 John Wiley & Sons, Ltd.     

Production of Biodegradable Polymer from Agro-Wastes in Alcaligenes sp. and Pseudomonas sp.

The present study was aimed to evaluate the suitability of agro-wastes and crude vegetable oils for the cost-effective production of poly-β-hydroxybutyrate (PHB), to evaluate growth kinetics and PHB production in Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1 with these carbon substrates and to study the biodegradation of PHB accumulated by these cultures. Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1 accumulates higher amounts of PHB corn (79.90% of dry cell mass) and rice straw (66.22% of dry cell mass) medium respectively. The kinetic model suggests that the Pseudomonas sp. RZS1 follows the Monod model more closely than A. faecalis RZS4. Both the cultures degrade their PHB extract under the influence of PHB depolymerase. Corn waste and rice straw appear as the best and cost-effective substrates for the sustainable production of PHB from Alcaligenes faecalis RZS4 and Pseudomonas sp. RZS1. The biopolymer accumulated by these organisms is biodegradable in nature. The agro-wastes and crude vegetable oils are good and low-cost sources of nutrients for the growth and production of PHB and other metabolites. Their use would lower the production cost of PHB and the low-cost production will reduce the sailing price of PHB-based products. This would promote the large-scale commercialization and popularization of PHB as an ecofriendly bioplastic/biopolymer.     

Anomalous scaling in epitaxial growth on vicinal surfaces: meandering and mounding instabilities in a linear growth equation with spatiotemporally correlated noise

We have undertaken an extensive analytical and kinetic Monte Carlo study of the (2+1) dimensional discrete growth model on a vicinal surface. A non-local, phenomenological continuum equation describing surface growth in unstable systems with anomalous scaling is presented. The roughness produced by unstable growth is first studied considering various effects in surface diffusion processes (corresponding to temperature, flux, diffusion anisotropy). We found that the thermally activated roughness is well-described by a generalized Lai–Das Sarma–Villain model with non linear growth continuum equation and uncorrelated noise. The corresponding critical exponents are computed analytically for the first time and show a continuous variation in agreement with simulation results of a solid-on-solid model. However, the roughness related to the meandering instability is found, unexpectedly, to be well described by a linear continuum equation with spatiotemporally correlated noise.     

Noether symmetry in the Nash theory of gravity

This paper deals with the study of Bianchi type-I universe in the context of Nash gravity by using the Noether symmetry approach. We shortly revisit the Nash theory of gravity. We make a short recap of the Noether symmetry approach and consider the geometry for Bianchi-type I model. We obtain the exact general solutions of the theory inherently exhibited by the Noether symmetry. We also examine the cosmological implications of the model by discussing the two cases of viable scenarios. Surprisingly, we find that the predictions are nicely compatible with those of the \(\Lambda \)CDM model.     

Large diaphragmatic defect as the cause of hydrothorax in a cirrhotic patient: demonstration with peritoneal scintigraphy and magnetic resonance imaging

A 52-year-old man with history of post-hepatitic cirrhosis presented with ascitis and respiratory distress. Chest X-ray on admission showed a large right hydrothorax. Thoracentesis yielded a large volume of a clear transudate fluid. Peritoneal scintigraphy showed rapid migration of radiotracer into the right pleural cavity, confirming the abdominal origin of the pleural fluid and suspecting a large diaphragmatic defect. MR imaging study using ultrafast sequences confirmed the large diaphragmatic defect.     

Fast spectrophotometric determination of titanium in rocks with 3,4-dihydroxybenzoic acid

A fast Spectrophotometric method has been developed for titanium determination in geological matrices, based on the mixture of the sample solution with an exact volume of a single chromogenic solution containing acetate buffer, ascorbic acid and 3,4-dihydroxybenzoic acid DHB, which forms with titanium(IV) ions a yellow complex with absorption maximum at 380 nm. The following parameters were studied: complex stability, pH effect, amount of DHB, amount of acetate buffer, obedience to Beer's law, amount of ascorbic acid and iron masking. The results demonstrated that titanium can be determined in the pH range 4.0–5.0, with a molar absorptivity of 1.43 × 10⁴ 1·mol^–1 cm^–1 and a limit of detection of 2.3 ng/ml. The methodology that allows analysis of 30 samples per hour. Common anions and cations do not interfere, even when present in large amounts. Iron(III) interference can be easily eliminated by reduction to iron(II) using ascorbic acid. Analytical characteristics of the proposed procedure, such as calibration sensitivity, analytical sensitivity, limit of detection and coefficient of variation, were determined. The procedure was applied for titanium determination in various standard geological matrices, with results of satisfactory accuracy and precision (RSD<1%).