Validated stability-indicating HPLC-UV method for simultaneous determination of glipizide and four impurities

A selective stability-indicating HPLC-UV method for simultaneous determination of glipizide and four impurities (DPs I-IV) formed under hydrolytic conditions was developed and validated. The drug and impurities were resolved on an XTerra C18 column (250 x 4.5 mm id) in a single gradient run using buffer (0.005 M KH2PO4; pH 3.0)-methanol (60 + 40, v/v; mobile phase A) and (20 + 80, v/v; mobile phase B) at a flow rate of 0.5 mL/min with 230 nm detection wavelength. The method was linear across concentration ranges of 0.2-100, 0.1-100, 0.5-100, 0.2-100, and 0.1-50 microg/mL for glipizide and DPs I-IV, respectively. The RSD for intraday and interday precision for the drug and impurities was < 1 and < 1.2%, respectively. Satisfactory recoveries (96.58-99.97%) of each of the three concentrations selected across the linearity range of each analyte were obtained, proving the method was sufficiently accurate. The LOD was 0.07, 0.05, 0.16, 0.08, and 0.05 microg/mL and the LOQ was 0.20, 0.14, 0.50, 0.23, and 0.14 microg/mL for the drug and DPs I-IV, respectively. Each peak was resolved with resolution of > 2 from the nearest peak. Insignificant changes in retention time (< 4%) and calculated amount (< 1.65%) of drug and each impurity upon small but deliberate changes in various chromatographic parameters were observed, suggesting the method was robust. The method was applied successfully to stability testing of glipizide tablets.     

New polymorphs of curcumin

Two new crystalline polymorphs and an amorphous phase of the active curcuminoid ingredient in turmeric are reported. Curcumin polymorph 2 has higher dissolution rate and better solubility than the known polymorph 1.     

Catalyst-free,facile, and an efficient synthesis of α-aminonitriles employing Zn(CN)2 as an ecofriendly cyanating agent

An efficient and eco-friendly method has been developed for the synthesis of α-aminonitriles via one-pot three-component condensation of carbonyl compounds, amines, and Zn(CN)₂ under mild conditions. This protocol has the features of use of inexpensive, ecofriendly readily available, effective cyanide source, high yield, and simple work-up procedure.     

The kinetics of the interaction of peroxy radicals. I. The Tertiary Peroxy Radicals

Existing data on the self-reactions of tertiary peroxy radicals RO₂ has been reanalyzed and corrected to deduce Arrhenius parameters for both termination and nontermination paths. For R = t-Butyl, these are logk_t(M^?1sec^?1) = 7.1 - (7.0/θ) and logk_nt(M^?1sec^?1) = 9.4 - (9.0/θ), respectively, different from those recommended by other authors. The higher magnitudes observed for termination processes of tertiary peroxy radicals like those of cumyl and 1,1-diphenylethyl have been discussed in terms of a much greater cage recombination of cumyloxy radicals as contrasted with t-butoxy radicals. It is shown that for benzyl peroxy radicals, the R—O bond dissociation energy is sufficiently low (18–20 kcal) that reversible dissociation into R^˙ + O₂ opens a competing second-order path to fast recombination R^˙ + RO → ROOR. This path is probably not important for cumyl peroxy radicals under usual experimental conditions but can become important for 1,1-diphenyl ethyl peroxy radicals at (O₂) < 10^?3M. At very low RO concentrations (<10^?5M), in the absence of added O₂, an apparent first-order disappearance of RO can occur reflecting the rate determining breaking of the cumyl—O bond followed by the second step above. The thermochemistry of RO is used to show that the reaction of R₂O₄ → 2RO + O₂ must be concerted and cannot proceed via RO which is too unstable and cannot form even from RO^˙ + O₂.     

Neuroinflammatory Markers: Key Indicators in the Pathology of Neurodegenerative Diseases

Neuroinflammation, a protective response of the central nervous system (CNS), is associated with the pathogenesis of neurodegenerative diseases. The CNS is composed of neurons and glial cells consisting of microglia, oligodendrocytes, and astrocytes. Entry of any foreign pathogen activates the glial cells (astrocytes and microglia) and overactivation of these cells triggers the release of various neuroinflammatory markers (NMs), such as the tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-1β (IL-10), nitric oxide (NO), and cyclooxygenase-2 (COX-2), among others. Various studies have shown the role of neuroinflammatory markers in the occurrence, diagnosis, and treatment of neurodegenerative diseases. These markers also trigger the formation of various other factors responsible for causing several neuronal diseases including Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), multiple sclerosis (MS), ischemia, and several others. This comprehensive review aims to reveal the mechanism of neuroinflammatory markers (NMs), which could cause different neurodegenerative disorders. Important NMs may represent pathophysiologic processes leading to the generation of neurodegenerative diseases. In addition, various molecular alterations related to neurodegenerative diseases are discussed. Identifying these NMs may assist in the early diagnosis and detection of therapeutic targets for treating various neurodegenerative diseases.     

Development of MWCNTs/alumina composite-based sensor for trace level ammonia gas sensing

Multi-walled carbon nanotube (MWCNT)/alumina (Al₂O₃) composite thin film-based low cost, rigid and highly efficient sensors were developed for trace level ammonia (NH₃) gas sensing applications. Composite films were prepared by dispersing MWCNTs in varying concentration in alumina solution following the sol-gel process. The sensor response as a function MWCNT concentrations were measured and compared. The notable characteristics of these sensors are fast response time (10 minutes), and excellent reproducibility with detection level up to 6 ppm. Although poor NH₃ desorption causes a high recovery time, fast and complete recovery was acquired using appropriate thermal treatment protocol. The sensitivity was found to be proportional to NH₃ concentrations in the range 6–25 ppm and then gradually saturated at higher concentrations. However, a decrease in the sensor response was observed with increase in concentrations of MWCNTs.     

The smart meter and a smarter consumer: quantifying the benefits of smart meter implementation in the United States

The electric grid in the United States has been suffering from underinvestment for years, and now faces pressing challenges from rising demand and deteriorating infrastructure. High congestion levels in transmission lines are greatly reducing the efficiency of electricity generation and distribution. In this paper, we assess the faults of the current electric grid and quantify the costs of maintaining the current system into the future. While the proposed "smart grid" contains many proposals to upgrade the ailing infrastructure of the electric grid, we argue that smart meter installation in each U.S. household will offer a significant reduction in peak demand on the current system. A smart meter is a device which monitors a household's electricity consumption in real-time, and has the ability to display real-time pricing in each household. We conclude that these devices will provide short-term and long-term benefits to utilities and consumers. The smart meter will enable utilities to closely monitor electricity consumption in real-time, while also allowing households to adjust electricity consumption in response to real-time price adjustments.     

On the isospin effects in the geometry of vanishing flow in heavy-ion collisions

We study the behavior of the geometry of vanishing flow (GVF) and its system size dependence at different incident energies. We find that the geometry of vanishing flow is sensitive to the incident energy. We also study the role of isospin degree of freedom through Coulomb potential, symmetry energy and nucleon-nucleon cross sections. Our study reveals that isospin degree of freedom through nucleon-nucleon cross section plays a dominant role compared to Coulomb potential and symmetry energy.     

Polymorphic form IV of olanzapine

2‐Methyl‐4‐(4‐methylpiperazin‐1‐yl)‐10H‐thieno[2,3‐b][1,5]benzodiazepine, C₁₇H₂₀N₄S, commonly known as olanzapine, is a psychotropic agent that belongs to the thienobenzodiazepine class of drugs. A new polymorph form IV was obtained upon attempted cocrystallization with nicotinamide in a 1:1 ratio from an ethyl acetate solution. Two butterfly‐like molecules form centrosymmetric dimers stabilized by weak C—H...π interactions between the 4‐methylpiperazin‐1‐yl fragment and the benzene/thiophene aromatic system. Form IV consists of a herringbone arrangement of dimers, whereas the previously reported form II has parallel dimers. Both crystal structures are sustained by an N—H...N hydrogen bond.