Synthesis, Crystal Structure and Characterization of a New Dabcodiium Hexaaquacobalt(II) Bis(Selenate), (C6H14N2)[Co(H2O)6](SeO4)2

Abstract  

The new hybrid material, cobalt selenate templated by 1,4-diazabicyclo[2.2.2]octane (abbreviated dabco), has been synthesised by the slow evaporation method at room temperature. Its crystal structure was investigated using single crystal X-ray diffraction data. It crystallises in the monoclinic system (space group P2₁/c) with the following unit-cell parameters: a = 12.9169(2) ?, b = 11.9101(2) ?, c = 12.4951(2) ?, β = 108.484(1)°, V = 1823.10(5) ?³ and Z = 4. The supramolecular structure of (C₆H₁₄N₂)[Co(H₂O)₆](SeO₄)₂ consists of isolated [Co(H₂O)]²⁺ and (C₆H₁₄N₂)²⁺ cations and (SeO₄)²⁻ anions linked together by three dimensional hydrogen-bond network. The infrared spectroscopy confirmed the presence of these different entities. The thermal behaviour of the precursor, studied by thermodiffractometry and thermogravimetric analyses, indicates that its decomposition proceeds through three stages giving rise to the cobalt oxide.     

Application of the green analytical procedure index to the simultaneous analysis of co-formulated tinidazole and ciprofloxacin in pure form,tablet dosage form,and human plasma using an environmentally friendly micellar high-performance thin-layer chromatographic technology

JPC – Journal of Planar Chromatography – Modern TLC - In individuals with chronic refractory pouchitis and other gastrointestinal disorders, the combination of ciprofloxacin (CIP) and...     

An equilibrium model of how regulative and normative institutions influence micro-economic and organizational behavior

This paper investigates how pre-existing institutions foster economic development through trade. A non-cooperative game-theoretic model is proposed that combines three strands of social science: economics, political science, and sociology. Idealized market participants follow rational decision theory within a reward structure that embodies two types of institutions. Regulative institutions operate on threat of punishment, and normative institutions on perceptions of what is good and right. This composite model allows a more quantitative analysis of the question, raised by Douglas North, of how societies diverge from the efficient state predicted by classical micro-economics. The main finding is that value can be created by different types of institution even when they are imperfect, and the range of minimum–maximum effectiveness varies with the types of economic transactions that are technologically possible. It is hoped that further refinements of the model will yield greater understanding of how the success of societies and organizations can be predicted by a few simple rules.     

Dielectric Properties of Polyimide‐Mica Hybrid Films

Summary: Polyimide‐mica hybrid films were prepared via ultrasonic dispersion and in situ polymerization process from a solution of a polyimide precursor and mica in N,N‐dimethylacetamide, and their structure was characterized by FTIR and XRD techniques. The dependence of dielectric properties, such as dielectric constant and electrical breakdown strength, of the hybrid films on the content of mica was studied at room and cryogenic temperatures. The results show that the dielectric constant of PI‐mica hybrid films decreases with the increase of the mica content at temperatures from −150 to 150 °C and at frequency range from 1 kHz to 1 MHz. It was found that the cryogenic electrical breakdown strength of the PI‐mica hybrid films could meet the requirements of cryogenic insulating materials.

Effect of frequency on the dielectric constant of PI‐mica hybrid films at 140 °C at the frequency from 1 kHz to 1 MHz.     

A new dabco templated metal sulfate, (C6H14N2)[Mn (H2O)6](SO4)2. Chemical preparation, hydrogen-bonded structure and thermal decomposition

The crystal structure of manganese sulfate templated by 1,4-diaza-bicyclo[2.2.2]octane (abbreviated dabco), (C₆H₁₄N₂)[Mn(H₂O)₆](SO₄)₂, was investigated using single crystal X-ray diffraction data. It crystallises in the monoclinic system (space group P2₁/c) with the following unit-cell parameters: a = 12.1392(2) ?, b = 12.3117(2) ?, c = 12.2765(2) ?, β = 104.607(1)°, V = 1775.47(5) ?³ and Z = 4. The structure has been solved using direct methods and refined by least-squares analysis [R ₁ = 0.0381, wR ₂ = 0.1082]. The crystal structure of the title compound is built from isolated [Mn(H₂O)₆]²⁺ octahedral cations, 1,4-diaza-bicyclo[2.2.2]octandiium cations (C₆H₁₄N₂)²⁺ and sulfate anions (SO₄)²⁻ connected by a three-dimensional hydrogen-bond network. The thermal decomposition of the precursor, studied by thermogravimetry and temperature-dependent X-ray powder diffraction, proceeds through four stages giving rise to the mixture of Mn₂O₃and Mn₃O₄. Supplementary Material CCDC 620298 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.     

Mastery of Cultural Conditions and Physico-chemical Properties Improves the Production and the Catalytic Efficiency of bglG

Stachybotrys microspora is a filamentous fungus secreting multiple β-glucosidases. Two of them were characterized. The third one, named bglG, was also characterized and used for various investigations. The current work undertakes the plausible role played by some cultural conditions and physico-chemical properties to improve bglG time course synthesis and also its catalytic efficiency. Indeed, bglG time course synthesis is slightly affected by light, but it is clearly affected by aeration and presence of baffle. On the same case, optimization of substrate and enzyme concentration contributes to the improvement of the catalytic efficiency of bglG. This biocatalyst tolerates a high ionic strength during its activity assay; β-mercaptoethanol increases the enzymatic rate. BglG has the capacity to hydrolyse efficiently oleuropéin, with a recovery of 88 %.     

Cyclic Thermodynamic Processes and Entropy Production

We study the time evolution of a periodically driven quantum-mechanical system coupled to several reservoirs of free fermions at different temperatures. This is a paradigm of a cyclic thermodynamic process. We introduce the notion of a Floquet Liouvillean as the generator of the dynamics of the coupled system on an extended Hilbert space. We show that the time-periodic state which the state of the coupled system converges to after very many periods corresponds to a zero-energy resonance of the Floquet Liouvillean. We then show that the entropy production per cycle is (strictly) positive, a property that implies Carnot's formulation of the second law of thermodynamics.     

The role of cholesterol in UV light B-induced apoptosis

Modification of major lipid raft components, such as cholesterol and ceramide, plays a role in regulation of programmed cell death under various stimuli. However, the relationship between cholesterol level modification and the activation of apoptotic signaling cascades upon UVB light has not been established. In this report, we demonstrate that upon UVB irradiation cholesterol levels in membrane rafts of skin cells increase, which leads to Fas-receptor (Fas) aggregation in the rafts. Utilizing a continuous velocity floatation technique, we show that Fas accumulated in the lipid rafts of human melanoma M624 cells after UVB irradiation. The subsequent events of death-inducing signaling complex formation were also detected in the lipid raft fractions. Depletion of cholesterol by methyl-β-cyclodextrin reduces Fas aggregation, while overloading increases. Disruption of lipid rafts also prevents Fas death domain-associated protein (Daxx) from dissociating from Fas in the lipid rafts, which is accompanied with a reduced apoptotic, but increased nonapoptotic death of UVB-irradiated human keratinocytes, HaCaT cells. Results indicate that cholesterol located in the plasma membrane of skin cells is required for lipid raft domain formation and activation of UVB-induced apoptosis.