X-ray crystal structure oftrans-dichlorobis(2,4,6-collidine)-copper(II)

The X-ray crystal structure oftrans-dichlorobis(2,4,6-collidine)copper(II) has been determined. Dark blue crystals of the complex crystallize in the monoclinic space group P2₁/c, with cell dimensionsa=7.527(3),b=14.732(4),c=7.951(4)Å and=92.79(9)°;V=880.6(6)ų andZ=2. 949 unique reflections withI _net>3(I) on refinement afforded values ofR=0.041 andR _w =0.048.     

Crystal structure of tylophorine methiodide monohydrate,C25H30NO 4 + I−·H2O

The crystal structure of tylophorine (Chemical name 2,3,6,7 tetramethoxy phenanthro [9,10:6, 7] indolizidine. Contribution No. 0871.) methiodide monohydrate has been determined. C₂₅H₃₀NO ₄ ⁺ I^–·H₂0, triclinic, P,a=8.831(1)Å, b=10.842(2),c=13.902(2), =105.0(1)^o, =104.7(1), =97.3(1),V=1210.22ų, Z=2,D _x =1.428 g./cm^–3, (CuK)=1.54184Å, (CUK)=107.2 cm^–1, F(000)=544,T=295^oK,R=0.038,Rw=0.046, for 2331 observed reflections withI2(I). Apart from van der Waals forces, the structure is stabilized by two hydrogen bonds of the type Ow(H) ... O and Ow(H) ... I^– involving the water molecule as the donor and atom O4 of the methoxy group and I^– as acceptors.     

PRIN: A Priority-Based Energy Efficient MAC Protocol for Wireless Sensor Networks Varying the Sample Inter-Arrival Time

Wireless sensor networks (WSNs) are used in a variety of applications to sense and transfer information to the centralized node with energy efficiency increasing the network’s lifespan. Other factors, such as quality of service (QoS) is also important to improve the performance of the WSNs, by increasing throughput and reducing end-to-end delay. In this paper, we evaluate the importance of QoS in the Medium Access Control (MAC) protocol for WSNs using different metrics and parameters such as energy efficiency, throughput, delay, and the network lifespan. We propose a new QoS MAC protocol, “PRIority in Node” (PRIN), using static priority in the source and the intermediate node and priority among the node which is one hop from the sink node to achieve QoS in WSNs. Simulation results are compared with those of the synchronous MAC protocol in terms of QoS parameters to show the improved performance of the proposed MAC protocol.     

Helix forming tendency of valine substituted poly-alanine: a molecular dynamics investigation

In this study, classical molecular dynamics simulations have been carried out on the valine (guest) substituted poly alanine (host) using the host-guest peptide approach to understand the role of valine in the formation and stabilization of helix. Valine has been substituted in the host peptide starting from N terminal to C terminal. Various structural parameters have been obtained from the molecular dynamics simulation to understand the tolerance of helical motif to valine. Depending on the position of valine in the host peptide, it stabilizes (or destabilizes) the formation of the helical structure. The substitution of valine in the poly alanine at some positions has no effect on the helix formation (deformation). It is interesting to observe the coexistence of 3 10 and alpha-helix in the peptides due to the dynamical nature of the hydrogen bonding interaction and sterical interactions.     

Synthesis of unsymmetrical substituted 1,4-dihydropyridines through thermal and microwave assisted [4+2] cycloadditions of 1-azadienes and allenic esters

Thermal and microwave assisted [4+2] cycloadditions of 1,4-diaryl-1-aza-1,3-butadienes with allenic esters lead to cycloadducts, which after a 1,3-H shift afford variedly substituted unsymmetrical 2-alkyl-1,4-diaryl-3-ethoxycarbonyl-1,4-dihydropyridines in high yields. Reactions carried out under microwave irradiation are cleaner and give higher yields with much shortened reaction times. Density functional theory (DFT) at the B3LYP/6-31G* level has been used to calculate geometric features of the reactants, barrier for s-trans to s-cis and reverse isomerization of azadienes (5a-d, 10a-e), dihedral angles between N(1), C(2), C(3), and C(4) atoms of azadienes along with various indices such as chemical hardness (eta), chemical potential (micro), global electrophilicity (omega), and the difference in global electrophilicity (Deltaomega) between the reacting pairs and Fukui functions (f (+) and f(-)). The results revealed that s-trans is the predominant conformation of azadienes at ambient temperature and the barrier for conversion of the s-trans rotamer of 1-azadienes to s-cis may be the major factor influencing the chemoselectivity, i.e., [4+2] verses [2+2] cycloaddition. The regiochemistry of the observed cycloadditions is collated with the obtained local electrophilicity indices (Fukui functions). Transition states for the formation of both [4+2] and [2+2] cycloadducts as located at the PM3 level indicate that the transition state for the formation of [4+2] cycloadducts has lower energy, again supporting the earlier conclusion that preferred formation of [4+2] cycloaaducts at higher temperature may be a consequence of barrier for s-trans to s-cis transformation of 1-azadienes.     

Synthesis and characterization of ternary nanocomposites of TiO2/rGO/CdS as an efficient catalyst for photo-degradation of methyl orange

Novel ternary composite photocatalysts have been successfully prepared by TiO₂ nanofibers, reduced graphene oxide, and CdS nanoparticles (TiO₂/rGO/CdS) by using electrospinning technique with easy chemical methods. The structures and their properties are examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscope (FESEM). The structural characterization of the composite reveals that pure TiO₂ NFs and CdS NPs crystalline very well and the reduced graphene oxide is tightly composed with TiO₂ NFs and CdS Nps. The photodegradation of methyl orange (MO) under UV light illumination is significantly enhanced compared with that of bare materials. This ternary composite degrades methyl orange within 75 min. The enhanced photocatalytic degradation performance resulted from effective separation of e–h pairs with rGO sheets and also contributed for high rate degradation efficiency. This novel ternary composite has a potential application of wastewater purification and utilization for energy conversions.     

High-affinity small molecule-phospholipid complex formation: binding of siramesine to phosphatidic acid

Siramesine (SRM) is a sigma-2 receptor agonist which has been recently shown to inhibit growth of cancer cells. Fluorescence spectroscopy experiments revealed two distinct binding sites for this drug in phospholipid membranes. More specifically, acidic phospholipids retain siramesine on the bilayer surface due to a high-affinity interaction, reaching saturation at an apparent 1:1 drug-acidic phospholipid stoichiometry, where after the drug penetrates into the hydrocarbon core of the membrane. This behavior was confirmed using Langmuir films. Of the anionic phospholipids, the highest affinity, comparable to the affinities for the binding of small molecule ligands to proteins, was measured for phosphatidic acid (PA, mole fraction of X(PA) = 0.2 in phosphatidylcholine vesicles), yielding a molecular partition coefficient of 240 +/- 80 x 10(6). An MD simulation on the siramesine:PA interaction was in agreement with the above data. Taking into account the key role of PA as a signaling molecule promoting cell growth our results suggest a new paradigm for the development of anticancer drugs, viz. design of small molecules specifically scavenging phospholipids involved in the signaling cascades controlling cell behavior.     

Production of Poly (3-Hydroxybutyric Acid) by <Emphasis Type="Italic">Ralstonia eutropha</Emphasis> in a Biocalorimeter and its Thermokinetic Studies

Bioplastic production from microbial sources is an emerging area which provides opportunities even to convert the wastes into bioplastics. Poly (3-hydroxybutyric acid), commonly called as PHB, is a bioplastic, which is stored as intracellular cytoplasmic inclusions in microorganisms. The objectives of this study are to calorimetrically monitor the PHB production and evaluate the thermokinetic data in a bioreaction calorimeter (BioRC1e). Thus, a well-known PHB-producing bacteria Ralstonia eutropha was selected for batch process in a bioreaction calorimeter. The metabolic heat generated was found to be correlated with the biomass, substrate consumption, oxygen uptake rate (OUR), carbon dioxide evolution rate (CER) and PHB production. The OUR pattern explained the oxidative metabolism of the strain R. eutropha. The heat yields due to biomass and glucose consumption during PHB production were found to be 12.56 and 13.56 kJ/g, respectively. The oxycalorific value obtained for the PHB production was 443.80 kJ/mol of O₂. The concentration of PHB obtained in BioRC1e was 4.33 g/L with a production rate of 0.09 g/L/h. The chemical structure of the extracted PHB by R. eutropha was confirmed using fourier transform infrared spectroscopy (FT-IR) and ¹H and ¹³C nuclear magnetic resonance (NMR) analysis.     

New ICT probes: synthesis and photophysical studies of N-phenylaza-15-crown-5 aryl/heteroaryl oxadiazoles under acidic condition and in the presence of selected metal ions

Molecular probes 6 and 7, incorporating N-phenylaza-15-crown-5 and aryl/heteroaryl oxadiazole have been designed to function as the new intramolecular charge transfer (ICT) probes. Photophysical properties have been studied under acidic condition as well as in the presence of selected metal ions, Ca²⁺, Ba²⁺, Mg²⁺, Na⁺, K⁺, and Li⁺. The changes in the ICT character of the probes, following the addition of trifluoroacetic acid, were interpreted in terms of site and degree of protonations. Based on the cation affinity, the ICT bands in both UV-vis and emission spectra experienced varying degrees of blue shifts due to removal of the aza-crown ether nitrogen from conjugation. The cation-induced spectral shifts and the stability constants revealed binding strength in the order Ca²⁺>Ba²⁺?Li⁺>Na⁺>K⁺>Mg²⁺. Competitive experiments performed in a matrix of ions also indicated superior interaction of 6 and 7 with Ca²⁺. The excited state decay profiles remained largely unperturbed in the presence of metal ions. The studied probes displayed positive solvatochromism and the Stokes shifts and excited state lifetimes increased with increasing solvent polarity. These findings can be rationalized by invoking highly polar nature of the emittive states. The chemoionophores 6 and 7 constitute potentially interesting Ca²⁺ sensitive probes due to their relatively high binding interaction for Ca²⁺ (log K_s=3.55-3.10) vis-a-vis that of biologically interfering Mg²⁺ (log K_s=1.67-1.30).