Poly[aqua([mu]3-2-hydroxy-5-nitrobenzoato-[kappa]3O1:O1':O2)rubidium]

In the structure of title compound [Rb2(C7H4NO2)2(H2O)2]n the centrosymmetric cyclic dimeric repeating unit comprises two irregular RbO4 complex centres bridged by the carboxylate groups of the 5-nitrosalicylate ligands. The coordination about each Rb is completed by a monodentate water molecule and a phenolic O donor which gives a bridging extension [Rb-O range 3.116(7)-3.135(5)A]. The two-dimensional polymeric structure is stabilized by intermolecular water O-H...O(carboxyl) hydrogen bonds and weak inter-ring pi--pi interactions [minimum ring centroid separation, 3.620(4)A].

Performance characteristics of compound curved sandwich shell structures

Sandwich shells have recently emerged as aesthetically pleasing, efficient and economical structural systems, with a number of applications. They combine the advantages of sandwich layer technology together with those of shell action. With different materials and thicknesses used in the sandwich layers, their performance characteristics largely remain un-quantified and there are no guidelines at present for their design. This research paper provides verification, through finite element modeling and testing, for the application of this technology to dome styled dwellings with research currently being conducted into the further application to roofing and floor structures.

Assessment of tumor prevention in Type 1 Neurofibromatosis using a nitroxide compound

Background Type 1 Neurofibromatosis (NF1) is a genetic disorder linked to mutations of the NF1 gene. Clinical symptoms are varied, but hallmark features of the disease include skin pigmentation anomalies (café au lait macules, skinfold freckling) and dermal neurofibromas. Method These dermal manifestations of NF1 have previously been reported in a mouse model where Nf1+/− mice are topically treated with dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA). We adopted this mouse model to test the protective effects of a nitroxide antioxidant, 5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl (CTMIO). Antioxidants have previously been shown to increase longevity in nf1-deficient fruitflies. Doses of 4 μM and 40 μM CTMIO provided ad libitum in drinking water were given to Nf1-deficient mice. Results Consistent with previous reports, Nf1-deficient mice showed a 4.7-fold increase in papilloma formation (P < 0.036). However, neither dose of CTMIO had any significant affect on papilloma formation. A non-significant decrease in skin pigmentation abnormalities was seen with 4 μM but not 40 μM CTMIO. Subsequent analysis of genomic DNA isolated from papillomas indicated that DMBA/TPA induced tumors did not exhibit a local loss of heterozygosity (LOH) at the Nf1 locus. Conclusion These data reveal that oral antioxidant therapy with CTMIO does not reduce tumor formation in a multistage cancer model, but also that this model does not feature LOH for Nf1.

Effect of a novel compound from Lycopodium obscurum L. on osteogenic activity of osteoblasts in vitro

We investigated the potential of an extract of Lycopodium obscurum L.; stigmastane-3-oxo-21-oic acid (SA), to enhance osteogensis of mouse osteoblastic MC3T3-E1 cells. SA at a concentration of 16 µM was found to have no significant effect upon the viability of the cells, thus concentrations of 8 µM and 16 µM of SA were used in all further experiments. Both concentrations of SA had an inhibitory affect upon alkaline phosphatase activity (ALP) after 8 days incubation, however, after 16 days activity was restored to control levels. However Alizarin red S staining showed increased levels of mineralization for both concentrations after 16 days culture. Real time PCR showed inhibition of genes Runx2 and Osterix genes responsible for the up-regulation of ALP. However early time point (8 days) up-regulation of bone matrix mineralization genes OPN and OCN, and late time point (16 days) up-regulation of both Jun-D and Fra-2 mRNA expression was significantly enhanced. These results suggest a potential me-chanism of SA in enhancing bone fracture healing is through the up-regulating bone matrix minera-lization.

Structural characterisation and environmental application of organoclays for the removal of phenolic compounds

Modified montmorillonite was prepared at different surfactant (HDTMA) loadings through ion exchange. The conformational arrangement of the loaded surfactants within the interlayer space of MMT was obtained by computational modelling. The conformational change of surfactant molecules enhance the visual understanding of the results obtained from characterization methods such as XRD and surface analysis of the organoclays. Batch experiments were carried out for the adsorption of p-chlorophenol (PCP) and different conditions (pH and temperature) were used in order to determine the optimum sorption. For comparison purpose, the experiments were repeated under the same conditions for p-nitrophenol (PNP). Langmuir and Freundlich equations were applied to the adsorption isotherm of PCP and PNP. The Freundlich isotherm model was found to be the best fit for both of the phenolic compounds. This involved multilayer adsorptions in the adsorption process. In particular, the binding affinity value of PNP was higher than that of PCP and this is attributable to their hydrophobicities. The adsorption of the phenolic compounds by organoclays intercalated with highly loaded surfactants was markedly improved possibly due to the fact that the intercalated surfactant molecules within the interlayer space contribute to the partition phases, which result in greater adsorption of the organic pollutants.

CO2 reforming of toluene as model compound of biomass tar on Ni/Palygorskite

Catalytic CO2 reforming of biomass tar on palygorskite-supported nickel catalysts using toluene as a model compound of biomass tar was investigated. The experiments were performed in a bench scale installation a fixed bed reactor. All experiments were carried out at 650, 750, 800 °C and atmospheric pressure. The effect of Ni loading, reaction temperature and concentration of CO2 on H2 yield and carbon deposit was investigated. Ni/Palygorskite (Ni/PG) catalysts with Ni/PG ratios of 0%, 2%, 5% and 8% were tested, the last two show the best performance. H2 yield and carbon deposit diminished with the increase of reaction temperature, Ni loading, and CO2 concentration.

A rapid and sensitive UPLC-ESI MS method for analysis of isofraxidin, a natural antistress compound, and its metabolites in rat plasma

Isofraxidin is one of the main bioactive constituents in the root of Acanthopanax senticosus, which has antifatigue, antistress, and immuno-accommondating effects. In this study, an ultraperformance LC (UPLC)-ESI MS method was developed for analyzing isofraxidin and its metabolites in rat plasma. The analysis was performed on a UPLC coupled with ESI MS (quadropole MS tandem TOF MS). The lower LOD (LLOD) for isofraxidin was 0.25 ng/mL, the intraday precision was less than 10%, the interday precision was less than 10%, and the extraction recovery was more than 80%. Isofraxidin and two metabolites (M1 and M2) were detected in rat plasma after oral administration of isofraxidin, and the molecular polarities of M1 and M2 were both increased compared to isofraxidin. The metabolites were identified as 5,6-dihydroxyl-7-methoxycoumarin and 5-hydroxyl-6,7-dimethoxycoumarin when subjected to parent ion spectra, product ion spectra, and extract mass and element composition analyses.

Synthesis and characterization of ternary AL-C-N compound

Efficient hydrogenated diamond-like carbon (DLC) film deposition in a plasma reactor that features both the capacitive and inductively coupled operation regimes is reported. The hydrogenated DLC films have been prepared on silicon wafers using a low-frequency (500 kHz) inductively coupled plasma (LF ICP) chemical vapor deposition (CVD) system. At low RF powers, the system operates as an asymmetric capacitively coupled plasma source, and the film deposition process is undertaken in the electrostatic (E) discharge regime. The films deposited in the electrostatic mode feature graphite-like structure. Above the mode transition threshold, the high-density inductively coupled plasma is produced in the electromagnetic (H) discharge regime. Raman spectrometry suggests the possibility to control relative proportions of sp2 and sp3 hybridized carbon. Variation of the DC substrate bias results in dramatic modification of the film structure from the polymeric (unbiased substrates) to the diamond-like (optimized bias). It has been shown that the deposition rate and hardness of the DLC film are much higher in the H-mode deposition regime. For a 20 m Torr H-mode CH4+Ar gas mixture discharge, the DLC film exhibits mechanical hardness of 18 GPa, Young's modulus of 170 GPa, and compressive stress of 1.3 GPa.

Deconstructing antiobesity compound action : requirement of serotonin 5-HT2B receptors for dexfenfluramine anorectic effects

The now-banned anorectic molecule, dexfenfluramine, promotes serotonin release through a serotonin transporter-dependent mechanism, and it has been widely prescribed for the treatment of obesity. Previous studies have identified that 5-HT(2B) receptors have important roles in dexfenfluramine side effects, that is, pulmonary hypertension, plasma serotonin level regulation, and valvulopathy. We thus investigated a putative contribution of 5-HT(2B) receptors in dexfenfluramine-dependent feeding behavior in mice. Interestingly, the hypophagic response to dexfenfluramine (3-10 mg/kg) observed in wild-type mice (1-4 h) was eliminated in mice lacking 5-HT(2B) receptors (5-HT(2B)(-/-)). These findings were further validated by the lack of hypophagic response to dexfenfluramine in wild-type mice treated with RS127445, a highly selective and potent antagonist (pKi=8.22 ± 0.24). Using microdialysis, we observed that in 5-HT(2B)(-/-) awake mice, the dexfenfluramine-induced hypothalamic peak of serotonin release (1 h) was strongly reduced (fourfold) compared with wild type. Moreover, using hypothalamic synaptosomes, we established the serotonergic neuron autonomous properties of this effect: a strong serotonin release was observed upon dexfenfluramine stimulation of synaptosome preparation from wild type but not from mice lacking active 5-HT(2B) receptors. These findings strongly suggest that activation of presynaptic 5-HT(2B) receptors is a limiting step in the serotonin transporter dependent-releasing effect of dexfenfluramine, whereas other serotonin receptors act downstream with respect to feeding behavior.

Study of the novel non-xanthine heterocyclic compound GU 285 as a potent non-selective adenosine receptor antagonist in the rat

The novel pyrazolo[3,4-d]pyrimidine compound GU285 (4-amino-6-alpha-carbamoylethylthio-1- phenylpyrazolo[3,4-d]pyrimidine, CAS 134896-40-5) was examined for its ability (1) to inhibit binding of adenosine (ADO) receptor ligands in rat brain membranes, (2) to antagonise functional responses to ADO agonists in rat right and left atria and coronary resistance vessels, and (3) to reduce the fall in heart rate and arterial blood pressure produced by the ADO A1 agonist N6-cyclopentyladenosine (CPA) in the intact, anaesthetized rat. GU285 competitively inhibited binding of the ADO A1 agonist [3H]-R-N6-phenylisopropyladenosine (R-PIA) yielding a Ki value of 11 (7-18) nmol.l-1 (geometric mean +/- 95% Cl). When assayed against the ADO A2A selective agonist [3H]-2-[p-(2-carboxyethyl)- phenethylamino]-5'-N-ethylcarboxamidoadenosine, (CGS21680), a Ki of 15 (10-24) nmol.l-1 was obtained. In spontaneously beating right atria, GU285 competitively antagonized negative chronotropic effects of R-PIA with a pA2 of 8.7 +/- 0.3 and in electrically paced left atria, GU285 competitively antagonized negative inotropic effects of R-PIA with a pA2 of 9.0 +/- 0.1. In the potassium-arrested, perfused rat heart GU285 (1 mumol.l-1) antagonized only the high sensitivity, ADO A2B mediated component of the biphasic relaxation of the coronary vasculature produced by NECA. The low sensitivity component was unchanged. GU285 (1 mumol.kg-1) antagonized the negative chronotropic and hypotensive effects of the adenosine A1 agonist CPA in anaesthetized rats, producing a 10-fold rightward shift in the dose-response relationship. These data demonstrate that in the rat, GU285 is a potent, non-selective adenosine receptor antagonist that maintains its activity in vivo.