Efficient and Convenient Method for Synthesis of Benzofuran-3-acetic Acids and Naphthafuran-acetic Acids

Herein, we report an efficient and convenient method for synthesis of benzofuran-3-acetic acids and naphthafuran-acetic acids 5a–p by the reaction of substituted-4-bromomethylcoumarins with aqueous sodium hydroxide at refluxing temperature. The obtained products are characterized by infrared, ¹H NMR, ¹³C NMR, and mass spectral data. Structures 5a and 5e are confirmed by their single x-ray diffraction studies. The advantages of this method are good yields, easy workup, and no chromatographic purifications.     

Synthesis of Benzofuran Derivatives: One Pot Synthesis of 2(3H) Benzofuranones

Phenols are condensed with cinnamic acids in the presence of trifluoroacetic acid to give high yields of the corresponding 2(3H) benzofuranones.     

Development of Multinuclear Polymeric Nanoparticles as Robust Protein Nanocarriers

One limitation of current biodegradable polymeric nanoparticles is their inability to effectively encapsulate and sustainably release proteins while maintaining protein bioactivity. Here we report the engineering of PLGA–polycation nanoparticles with a core–shell structure that act as a robust vector for the encapsulation and delivery of proteins and peptides. The optimized nanoparticles can load high amounts of proteins (>20 % of nanoparticles by weight) in aqueous solution without organic solvents through electrostatic interactions by simple mixing, thereby forming nanospheres in seconds with diameters <200 nm. The relationship between nanosphere size, surface charge, PLGA–polycation composition, and protein loading is also investigated. The stable nanosphere complexes contain multiple PLGA–polycation nanoparticles, surrounded by large amounts of protein. This study highlights a novel strategy for the delivery of proteins and other relevant molecules.     

An analytical algorithm for the evaluation of two-electron integrals in diatomics: A test calculation with an elliptical basis set

A purely analytical method designed to compute the two-electron integrals that appear in anab-initio calculation of the electronic structures of diatomic molecules using elliptical basis set is presented. Test calculations are successfully carried out on LiH molecule.     

Performance of Multi-Antenna Signaling Strategies Using Dual-Polarized Antennas: Measurement Results and Analysis

Multiple-input multiple-output (MIMO) wireless systems employ spatialmultiplexingto increase spectral efficiency or transmit diversity (space-time coding)techniques to improve link reliability.The performance of these signaling techniques is highly dependent on channelcharacteristics whichin turn depend on antenna height and spacing and richness of scattering. Theuse ofdual-polarized antennas is a cost- and space-effective alternative where twospatially separated uni-polarized antennas can be replaced by a singledual-polarizedantenna element. In this paper, we use fixed-wireless experimental datacollected in atypical suburban environment at 2.5 GHz to investigate the performance ofspatialmultiplexing and transmit diversity (Alamouti scheme) for a dual-polarizedantennasetup. Channel measurements were conducted over a cell of radius 7 km andchannel statistics such as K-factor, cross-polarizationdiscrimination (XPD), and fading signal correlation were extracted fromthe gathered data. At each location, differentcombinations of these parametersyield different performance (measured in terms of average uncoded bit errorrate)of spatial multiplexing and the Alamouti scheme.The results indicate that proper selection of the transmissionmode through feedback, if possible, can reduce thebit error rate by several orders of magnitude. Furthermore, the resultshint at the existence of a preferred-mode switching distance within a cell– above/below which one mode of transmission exhibits generally superiorperformance.     

Potential Application of Alkaline Pectinase from <Emphasis Type="Italic">Bacillus subtilis</Emphasis> SS in Pulp and Paper Industry

Pectinase production from Bacillus subtilis SS was optimized under solid-state fermentation (5,943 U/g of dry bacterial bran). The pectinase produced was stable in neutral to alkaline pH range at 70 degrees C; therefore, the suitability of this pectinase in pulp and paper industry was investigated. The enzyme pretreatment process was optimized, and a pectinase dose of 5 IU/g of oven-dried pulp (10% consistency) at pH 9.5 temperature 70 degrees C after 150 min of treatment gave the best pretreatment to the pulp. An increase of 4.3% in brightness along with an increase of 14.8 and 65.3% in whiteness and fluorescence, respectively, whereas a 15% decrease in the yellowness of the pretreated pulp were observed. There was a 5.85% reduction in kappa number and 6.1% reduction in permanganate number along with a reduction in the chemical oxygen demand value. Significant characteristics showed by pectinase open new possibilities of application of this cellulase-free enzyme in the pulp and paper industry by reducing the negative environmental impact of chemicals apart from improving the properties of paper.     

Pyridine-2-thione (pySH) derivatives of silver(I): Synthesis and crystal structures of dinuclear [Ag2Cl2(μ-S-pySH)2(PPh3)2] and [Ag2Br2(μ-S-pySH)2(PPh3)2] complexes

Reaction of silver(I) halides with PPh₃ in acetonitrile and then with pyridine-2-thione (pySH) chloroform (1:1:1 molar ratio) has yielded sulfur bridged dimers of general formula, [Ag₂X₂(μ-S-pySH)₂(PPh₃)₂] (X = Cl, 1, Br, 2). Both these complexes have been characterized using analytical data, NMR spectroscopy and single crystal X-crystallography. The central Ag₂S₂ cores form parallelograms with unequal Ag–S bond distances (2.5832(8), 2.7208(11) Å) in 1 and (2.6306(4), 2.6950(7) Å) in 2, respectively. The Ag?Ag contacts of compounds 1 and 2 are 3.8425(8) and 3.8211(4) Å, respectively. The angles around Ag (in the range 87.19(2)–121.71(2)° in 1 and 87.81(2)–121.53(2)° in 2) reveal highly distorted tetrahedral geometry. There are inter dimer π–π stacking interactions between pyridyl rings (inter ring distances of 3.498 and 3.510 Å in complexes 1 and 2, respectively). The solution state ³¹P NMR spectroscopy has shown the existence of both monomers and dimers. The studies reveal relatively weaker intramolecular –NH?Cl hydrogen bonding in case of AgCl vis-à-vis that in CuCl which favored both a monomer and a dimer with AgCl, and only a monomer with CuCl.