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锌 purum, powder; CAS Number: 7440-66-6; find Sigma-Aldrich-96454 MSDS, related peer-reviewed papers, technical documents, similar products & more at Sigma-Aldrich

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Selective Fries rearrangement catalyzed by zinc powder.

Zinc powder as an effective reducing reagent during liquid-phase oxidation of benzene to phenol using molecular oxygen over V-substituted heteropoly acid catalysts.

Ultrasonication-assisted ultrafast reduction of graphene oxide by zinc powder at room temperature.

One-pot reductive cleavage of exo-olefin to methylene with a mild ozonolysis-Clemmensen reduction sequence.

Highly efficient, general procedure for the preparation of alkylzinc reagents from unactivated alkyl bromides and chlorides.

Structural features, synthesis, and reactivity of Zn-biphenyl metal-organic frameworks with MOF-5 topology are presented to show the chemical flexibility of such materials and to demonstrate the challenges that can be encountered and solved to avoid interpenetration. We introduce the synthesis of a Zn-biphenyl MOF with diphenylphosphino functionalization and illustrate its structural and chemical properties.

Synthesis and reactivity of Zn-biphenyl metal-organic frameworks, introducing a diphenylphosphino functional group.

Studies in rodents indicate that the disruption of P-glycoprotein (P-gp) function increases drug distribution into the developing fetus and organs such as the brain. To simultaneously and serially evaluate the effect of P-gp activity and inhibition on the tissue distribution of drugs in a more representative animal model, we tested the feasibility of conducting whole-body PET of the pregnant nonhuman primate (Macaca nemestrina). We used (11)C-verapamil as the prototypic P-gp substrate and cyclosporine A (CsA) as the prototypic inhibitor. Four pregnant macaques (gestational age, 145-159 d; gestational term, 172 d) were imaged after the intravenous administration of (11)C-verapamil (30-72 MBq/kg) before and during intravenous infusion of CsA (12 or 24 mg/kg/h, n = 2 each). The content of verapamil and its metabolites in plasma samples was determined using a rapid solid-phase extraction method. The plasma and tissue time-radioactivity concentration curves of (11)C were integrated over 0-9 min after each verapamil injection. The tissue or arterial plasma area under the time-concentration curve (AUC(tissue)/AUC(plasma)) served as a measure of the tissue distribution of (11)C radioactivity. CsA effect on (11)C radioactivity distribution was interpreted as P-gp inhibition. The change in the fetal liver AUC ratio served as a reporter of placental P-gp inhibition. CsA effect on tissue distribution of (11)C radioactivity (AUC ratios) did not increase with the mean blood concentration of CsA, indicating a near-maximal P-gp inhibition. CsA increased maternal brain and fetal liver distribution of (11)C radioactivity by 276% +/- 88% (P < 0.05) and 122% +/- 75% (P < 0.05), respectively. Changes in other measured tissues were not statistically significant. These data demonstrate for the first time, to our knowledge, the feasibility of simultaneous, serial, noninvasive imaging of P-gp activity and inhibition in multiple maternal organs and the placenta in the nonhuman primate. Our findings, consistent with previous data in rodents, indicate that the activity of P-gp in the placenta and the blood-brain barrier is high and that the inhibition of P-gp facilitates drug distribution across these barriers.

Simultaneous PET imaging of P-glycoprotein inhibition in multiple tissues in the pregnant nonhuman primate.

To determine the serum zinc level in patients with pneumonia. The descriptive cross-sectional study was conducted at the Liaquat University Hospital, Hyderabad, Pakistan, from September 2008 to February 2009. All patients above 12 years of age and of either gender who had been diagnosed with pneumonia were further evaluated for their serum zinc status.The data was analysed through SPSS 10.00, and p<0.05 was considered statistically significant. The mean age of the 118 patients in the study was 25.64 +/- 6.53 years. The mean serum zinc level was 8.279 +/- 2.77 mmol/L, while the mean serum zinc levels in patients having low and normal levels was 6.740 +/- 1.47 mmol/L and 13.243 +/- 1.52 mmol/L respectively (p<0.001). The serum zinc was low in 42 of the 72 (58%) males, and 35 of the 46 (76%) females (p<0.04). There was also significant difference between mean serum zinc level in male and female patients (p<0.03). Out of 77 (65%) hypozincaemic patients, 69 (90%) recovered, while 08 (10%) failed to recover) during their hospital stay (p<0.33). Of the 69 who recovered, 29 (42%) patients did so in less than 2 weeks, while 40 (58%) patients recovered in more than 02 weeks. Serum zinc level was found to be low in patients with pneumonia.

Serum zinc level in patients with pneumonia: a six-month long cross-sectional descriptive study at Liaquat University Hospital Hyderabad, Sindh, Pakistan.

Alzheimer's disease, is a lethal neurodegenerative pathology, characterized by the formation of soluble neurotoxic oligomers of the human amyloid-beta peptide Abeta which get accumulated forming polymeric extracellular aggregates (so-called amyloid plaques). The isomerized at aspartate 7 isoform of the human Abeta (isoAbeta) is the main component of these plaques and is considered as the potential pathogenic agent of AD. Besides this, there is a possible generation mechanism for this isoform from a genetically deficient D7N Abeta variant (Tottori mutation). On the contrary the rodent Abeta (rat Abeta), which has three amino acid substitutions in its metal-binding domain, is not susceptible to pathogenic aggregation in vivo, unlike the other known natural isoforms of Abeta. Interactions with zinc ions play a crucial role in the aggregation of monomeric human Abeta in vitro and in vivo. In the presented article using high resolution ESI-MS methods it was shown that domains 1-16 of isoAbeta and D7NAbeta bind zinc ions in the exactly the same manner as the normal human Abeta1-16, whereas ratAbeta has significant differences in structure of its minimal zinc binding center. These results confirm the overall interaction mechanism between zinc ions and the humanAbeta isoforms and allows to suppose that perhaps modulation of the structure of region 6-14 of Abeta can be used as a promising therapeutic approach to AD treatment.

[Identification of the minimal zinc-binding center in natural isoforms of amyloid-beta domain 1-16 using ESI-MS].

The ability for usage of common freshwater charophytes, Chara aculeolata and Nitella opaca in removal of cadmium (Cd), lead (Pb) and zinc (Zn) from wastewater was examined. C. aculeolata and N. opaca were exposed to various concentrations of Cd (0.25 and 0.5 mg/L), Pb (5 and 10 mg/L) and Zn (5 and 10 mg/L) solutions under hydroponic conditions for 6 days. C. aculeolata was more tolerant of Cd and Pb than N. opaca. The relative growth rate of N. opaca was drastically reduced at high concentrations of Cd and Pb although both were tolerant of Zn. Both macroalgae showed a reduction in chloroplast, chlorophyll and carotenoid content after Cd and Pb exposure, while Zn exposure had little effects. The bioaccumulation of both Cd and Pb was higher in N. opaca (1544.3 microg/g at 0.5 mg/L Cd, 21657.0 microg/g at 10 mg/L Pb) whereas higher Zn accumulation was observed in C. aculeolata (6703.5 microg/g at 10 mg/L Zn). In addition, high bioconcentration factor values (> 1000) for Cd and Pb were observed in both species. C. aculeolata showed higher percentage of Cd and Pb removal (> 95%) than N. opaca and seemed to be a better choice for Cd and Pb removal from wastewater due to its tolerance to these metals.

Phytoremediation potential of charophytes: bioaccumulation and toxicity studies of cadmium, lead and zinc.

Porous coordination polymers (PCPs)/metal-organic frameworks (MOFs) are inorganic-organic hybrid materials with a permanent three-dimensional porous metal-ligand network. PCPs or MOFs are inorganic-organic analogs of zeolites in terms of porosity and reversible guest exchange properties. Microporous water-stable PCPs with high water uptake capacity are gaining attention for low temperature heat transformation applications in thermally driven adsorption chillers (TDCs) or adsorption heat pumps (AHPs). TDCs or AHPs are an alternative to traditional air conditioners or heat pumps operating on electricity or fossil fuels. By using solar or waste heat as the operating energy TDCs or AHPs can significantly help to minimize primary energy consumption and greenhouse gas emissions generated by industrial or domestic heating and cooling processes. TDCs and AHPs are based on the evaporation and consecutive adsorption of coolant liquids, preferably water, under specific conditions. The process is driven and controlled by the microporosity and hydrophilicity of the employed sorption material. Here we summarize the current investigations, developments and possibilities of PCPs/MOFs for use in low-temperature heat transformation applications as alternative materials for the traditional inorganic porous substances like silica gel, aluminophosphates or zeolites.

Porous coordination polymers as novel sorption materials for heat transformation processes.

Black gram plants subjected to varying levels of Zn supply (0.01 to 10 microM Zn) showed optimum growth and dry matter yield in plants receiving 1 microM Zn. The dry matter yield of plants decreased in plants receiving 0.01 and 0.1 microM Zn (deficient) and excess levels of Zn (2 and 10 microM Zn). The plants grown with Zn deficient supply showed delayed flowering, premature bud abscission, reduced size of anthers, pollen producing capacity, pollen viability and stigma receptivity resulting in poor pod formation and seed yield. Providing Zn as a foliar spray at pre-flowering stage minimized the severity of Zn deficiency on reproductive structure development and enhanced the seed nutritional status by enhancing seed Zn density, seed carbohydrate (sugar and starch content) and storage proteins (albumins, globulins, glutenins, and prolamines).

Foliar application of Zn at flowering stage improves plant's performance, yield and yield attributes of black gram.

Research on the zinc status of osteoporotic women is scarce. This randomized, double-blind, placebo-controlled clinical trial assessed the effect of zinc supplementation on serum zinc and calcium levels in postmenopausal osteoporotic women. A sample of 60 women referred to a rheumatology clinic in Tabriz were randomly divided into intervention (220 mg zinc sulfate daily) and placebo groups. Anthropometric indices, dietary intake of zinc and calcium and serum zinc and calcium were assessed at baseline and after 60 days. Mean serum zinc concentrations were markedly lower than the normal range at baseline, but mean serum calcium levels were normal. In the intervention group serum levels were significantly higher after 60 days [120.5 (SD 7.5) versus 70.5 (SD 4.6) micrograms/dL] while serum calcium levels were unchanged [8.6 (SD 0.1) versus 9.1 (SD 0.3) mg/dL]. The placebo group showed no significant changes in zinc or calcium levels. Postmenopausal osteoporotic women may benefit from zinc supplementation.

Effect of zinc supplementation on serum zinc and calcium levels in postmenopausal osteoporotic women in Tabriz, Islamic Republic of Iran.

In the paper the relation between the changes of a functional condition of ileum, composition of its microflora and secretory activity of Paneth cells has been investigated. Administration of lincomycin led to a reduction of total of symbiotic bacteria and appearance of opportunistic microflora. Statistically insignificant changes of speed of transit of intestinal contents and damage of barrier function of an intestinal epithelium were noted. The intestinal epithelium was characterized by signs of inflammation. Administration of indomethacin and methotrexate led to significant changes of a functional state of a small intestine of rats. The speed of transit of intestinal contents following indomethacin administration increased by 30%, and, on the contrary, decreased by 90% following administration of methotrexate. The ability of epithelium of ileum to adsorb vital dye in both cases increased (by 32 and 51%, respectively) indicating the damage of barrier function. Thus there were significant changes in structure of microflora of ileum: reduction of quantity symbiotic and emergence of opportunistic microflora, a translocation of bacteria to a mucous wall. It was concluded that animal of all three experimental groups had a reduction of the contents of cationic proteins and zinc in the secretory granules of Paneth cells. These results can testify that balance changes between simbiotic and opportunistic microflora are a factor which has an impact on intestine damage and also causes activation of secretory function of Paneth cells.

[Functional state of the ileum, cationic peptids and zinc content in the Paneth cells of the rats following lincomycin, indomethacin and methotrexate andministration].

ZnFe2O4 nanoparticles (ZFNPs) were developed as catalyst for the degradation of benzotriazole (BTA) by heterogeneous photoelectro-Fenton (PE-Fenton) like process. ZFNPs were prepared by a co-precipitation process and then characterized with transmission electron microscopy (TEM), X-ray fluorescence (XRF), X-ray diffraction (XRD) and BET surface area. Using such ZFNPs as catalyst, the degradation of BTA was investigated. Due to the high catalytic activity of ZFNPs, PE-Fenton like process showed efficient degradation of BTA. The influencing factors such as pH, dosage of ZFNPs, applied potential and initial concentration of BTA were systematically investigated. Under the optimum conditions, 91.2% of BTA was removed after 180 min treatment.

Removal of benzotriazole by heterogeneous photoelectro-Fenton like process using ZnFe2O4 nanoparticles as catalyst.

The paper presents an analysis of authors' results obtained using fixation of various tissues in zink-ethanol-formaldehyde (ZEF). It was found that fixation in ZEF, in comparison with other methods of fixation, allowed to achieve higher sensitivity of immunocytochemical reaction for a large number of antigens studied and, in many cases, to avoid heat unmasking of antigens. It also provided high resolution of the images obtained using the fluorescent and confocal laser microscopy. However, the studies of antigens with small molecular mass revealed the antigen diffusion from the site of original localization. The data obtained suggest that fixation of a material in ZEF fixative is promising for both immunocytochemical studies, including those using the fluorescent and confocal laser microscopy, and general histological practice.

[Advantages and disadvantages of zink-ethanol-formaldehyde as a fixative for immunocytochemistry and confocal laser microscopy].

The complex formation reaction, between fluoroquinolones (FQ): ciprofloxacin (CPX), enoxacin (ENX), enrofloxacin (ENRX), lomefloxacin (LOMX), levofloxacin (LEVX), ofloxacin (OFX), norfloxacin (NFX), sparfloxacin (SPRX) and aluminum(III), iron(III), copper(II) and zinc(II) ions were investigated. The spectrophotometic titration method in a wide range of pH was utilized for estimation of complex formation equilibrium. The application of Bjerrum method allowed to estimate the complex equilibrium of analyzed species in the reaction mixture. The overall stability constants (logbeta(pqr)) of fluoroquinolones complexes with metal ions were calculated using HYPRERQUAD program. The most stable complexes FQ were created with iron(III) and aluminum(III) and than copper(II) and zinc(II) ions, respectively. The highest values of calculated logbeta(pqr) were obtained for the Me(FQ)3H3 species and the lowest for the Me(FQ)2OH forms. Furthermore, an additional studies have been performed. The effect of the polyvalent metal ions on the complex structure has been investigated. The IR and 1H, 13C and 19F NMR spectroscopy methods were used for the confirmation of the structure of the FQ-Me complex formations. The most significant shifts of signals of 1H NMR spectra of the fluoroquinolones and their complexes were found for the protons substituted in the positions 2, 5 and 8, whereas the 13C NMR spectra showed up the shifts changes for carbon atoms in positions 2, 3, 3a and 4.

Spectroscopic investigations of fluoroquinolones metal ion complexes.

This article attempts to highlight the prevalence of zinc deficiency and its health and economic consequences in South Asian developing countries and to shed light on possible approaches to combating zinc deficiency. A computer-based search was performed on PubMed, Google, and ScienceDirect.com to retrieve relevant scientific literature published between 2000 and 2012. The search yielded 194 articles, of which 71 were culled. Studies were further screened on the basis of population groups, age and sex, pregnancy, and lactation. The most relevant articles were included in the review. Cutoffs for serum zinc concentration defined for zinc deficiency were 65 microg/dL for males and females aged < 10 years, 66 microg/dL for non-pregnant females, and 70 microg/dL for males aged > or = 10 years. Population segments from rural and urban areas of South Asian developing countries were included in the analysis. They comprised pregnant and lactating women, preschool and school children. The analysis reveals that zinc deficiency is high among children, pregnant and lactating women in India, Pakistan, Bangladesh, Sri Lanka, and Nepal. Diarrhoea has been established as a leading cause to intensify zinc deficiency in Bangladesh. Little has been done in Sri Lanka and Nepal to estimate the prevalence of zinc deficiency precisely. A substantial population segment of the South Asian developing countries is predisposed to zinc deficiency which is further provoked by increased requirements for zinc under certain physiological conditions. Supplementation, fortification, and dietary diversification are the most viable strategies to enhancing zinc status among various population groups.

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