Syntheses and antibacterial studies of some 2-[5-(Aryl)-[1,3,4]oxadiazole-2-ylsulfanyl] alkanoic Acids

Some new 2-[5-(aryl)-[1,3,4]oxadiazole-2-ylsulfanyl]alkanoic acids were synthesized and studied for their antibacterial activity. These compounds were prepared from aromatic carboxylic acid hydrazides. Aromatic carboxylic acid hydrazides 1 on refluxing with carbon disulfide and methanolic potassium hydroxide and then on subsequent acidification with hydrochloric acid furnish 5-aryl-1,3,4-oxadiazole-2-thiones 2. 2-Chloro alkanoic acids react with 2 in alkaline media and on acidification yield the title compounds 3. These compounds were characterised by CHN analyses, IR, mass and ¹H NMR spectral data. All the compounds were evaluated for their in vitro antibacterial activity against two Gram negative strains (Escherichia coli and Pseudomonas aeruginosa) and two Gram positive strains (Bacillus subtilis and Staphylococcus aureus) and their minimum inhibitory concentration (MIC) were determined.     

Exchange and correlation effects on density excitation spectra of metallic quantum wires at finite temperature

We have studied the effect of exchange and correlations on the density excitation spectra of metallic quantum wires at finite temperature. The correlations are treated by incorporating the first-order self and exchange contributions into the random-phase approximation (RPA). Numerical results are presented for the spectra of the density response function and the plasmon dispersion for the gold wire on Si(557) substrate-a system studied recently by Nagao et al. (2006 Phys. Rev. Lett. 97 116802) for plasmons using electron energy loss spectroscopy. Our results for plasmons are found to agree with the experimental data. Though the first-order correction is small at currently accessible wire parameters, it becomes significant with increasing coupling parameter r(s). The effect of temperature on plasmons is found to be small for the wire system investigated experimentally. However, temperature has a significant effect on the spectra of the response function. We have also calculated the static structure factor, the pair-correlation function and the correlation energy at zero temperature in the first-order theory to check its applicability in dealing with correlations. Results are compared directly with the available Monte Carlo simulation data. It is found that the static correlation functions improve significantly over the RPA with the increase of r(s). On the other hand, the correlation energy shows very good agreement for r(s) ≤ 5 and wire widths b ≥ a(0). For smaller b, the agreement is good up to relatively smaller r(s).     

Investigation of carrier scattering mechanisms in molybdenum diselenide single crystals by hall effect measurements

Molybdenum diselenide (MoSe₂) belong to the large family of layered transition metal dichalcogenides. It consists of weakly coupled sandwiched layers i.e. Se – Mo – Se in which a Mo atom layer is enclosed within two Se layers. This structure makes MoSe₂ extremely anisotropic in character and leads to unusual structural properties. In addition, MoSe₂ possess flexible nature along with good carrier mobility to make them potential candidate for fabricating flexible high mobility electronic devices such as Schottky barrier devices, FETs, solar cell etc. In context of this authors made an effort to study the low temperature (12 < T < 300 K) electronic transport properties of Molybdenum diselenide (MoSe₂). Through the investigation the temperature dependent Hall mobility study revealed that the grown crystals of MoSe₂possess a mixed scattering mechanism. It has been found that observed temperature dependant mobility has at least two transitions from lattice to impurity scatterings showing an imprint of multicarrier nature of this semiconductor originating from its complex band structure. It has been observed that the studied crystals have at least two group of carriers of differing origins in which transition between dominant scattering mechanisms occur at different temperatures. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

MPEG-4 video transmission over UMTS mobile networks

This paper presents an overview [1] of the MPEG-4 (Motion Picture Experts Group) coded video file structure and the VOP (Video Object Plane) types followed by classification of errors and introduction of the NEWPRED mechanism in MPEG-4 for error concealment. An UEP (Unequal Error Protection) scheme is described with a discussion on how the proposed scheme affects the UMTS (Universal Mobile Telecommunications System) network efficiency. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Discerning the stability behaviour of mavacamten availing liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy: In silico toxicity and mutagenicity prediction of degradation products

The present study aimed to separate, identify, and characterise the degradation products formed when mavacamten is exposed to stress degradation as well as the stability of the drug in various environments and also to understand its degradation chemistry. Prediction of in silico toxicity and mutagenicity was aimed at the observed degradation products. Stress degradation along with stability studies and degradation kinetics were performed on mavacamten, and separation of degradation products was carried out by high-performance liquid chromatography. Tandem mass spectrometry studies were executed to characterise the structures of degradation products using product ion fragments. Orthogonally, nuclear magnetic resonance experiments were conducted to elucidate the structures having ambiguity in characterising them. Deductive Estimation of Risk from Existing Knowledge and Structure Activity Relationship Analysis using Hypotheses software were used to establish in silico toxicity and mutagenic profiles of mavacamten and its degradation products. Two degradation products of mavacamten found in acidic hydrolytic stress conditions were separated, identified, characterised, and proposed as 1-isopropylpyrimidine-2,4,6(1H,3H,5H)-trione and 1-phenylethanamine. Mavacamten was found to be stable under different pH and gastrointestinal conditions. The degradation kinetics of mavacamten under 1 N acidic condition followed zero-order kinetics, and it was degraded completely within 6 h. In silico toxicity and mutagenicity studies revealed that 1-phenylethanamine can be a skin sensitiser. A high-performance liquid chromatography method was developed for the separation of degradation products of mavacamten and characterised by liquid chromatography–tandem mass spectrometry and nuclear magnetic resonance. During the manufacturing and storage of drug product, precautions need to be taken when dealing with acidic solutions as the drug is prone to hydrolysis in acidic conditions. The formation of 1-phenylethanamine under these conditions is to be monitored as it is a skin sensitiser.     

Heteroatom-Doped Metal-Free Carbon Nanomaterials as Potential Electrocatalysts

In recent years, heteroatom-incorporated specially structured metal-free carbon nanomaterials have drawn huge attention among researchers. In comparison to the undoped carbon nanomaterials, heteroatoms such as nitrogen-, sulphur-, boron-, phosphorous-, etc., incorporated nanomaterials have become well-accepted as potential electrocatalysts in water splitting, supercapacitors and dye-sensitized solar cells. This review puts special emphasis on the most popular synthetic strategies of heteroatom-doped and co-doped metal-free carbon nanomaterials, viz., chemical vapor deposition, pyrolysis, solvothermal process, etc., utilized in last two decades. These specially structured nanomaterials’ extensive applications as potential electrocatalysts are taken into consideration in this article. Their comparative enhancement of electrocatalytic performance with incorporation of heteroatoms has also been discussed.