A Sensitive Resonance Rayleigh Scattering Method for Na+ Based on Graphene Oxide Nanoribbon Catalysis

The gold nanoparticle reaction of HAuCl4-H2O2 was very slow under 60°C, and the as-prepared graphene oxide nanoribbons (GONRs) exhibited strong catalysis of the reaction to form gold nanoparticles (AuNP) that appeared a resonance Rayleigh scattering (RRS) peak at 550 nm. Upon addition of potassium pyroantimonate (PA) ligand, it was adsorbed on the GONRs surface to inhibit the catalysis to cause the RRS peak decreasing. When the analyte of Na+ was added, the coordination reaction between PA and Na+ took place to form the stable complexes of [Na2(PA)] to release free GONRs catalyst that resulted in the RRS peak increasing linearly. Accordingly, a new and sensitive RRS method for Na+ was established, with a linear range of 0.69-25.8 nmol/L and a detection limit of 0.35 nmol/L Na+.

Synthesis and Properties Study of the Green High-Efficient Corrosion and Scale Inhibitor

The synthetic imidazoline-ammonium-salt corrosion inhibitor was compounded with sodium sulfite, isopropanol and potassium pyroantimonate respectively. Potassium pyroantimonate was selected as the best compound with good synergy. And the ratio of potassium pyroantimonate and the corrosion inhibitor was 3:50. Compared to the imidazoline corrosion inhibitor separately used, the inhibition efficiency was improved about 1.2% when the amount of the potassium pyroantimonate was 0.03%. Through researching the synergistic effect with polyaspartic acid, the green and high-efficient corrosion and scale inhibitor is got which is applicable to oilfield.

The low doses effect of experimental zearalenone (ZEN) intoxication on the presence of Ca2+ in selected ovarian cells from pre-pubertal bitches

The objective of this study was to determine the effect of 42-day ZEN intoxication on the presence of Ca2+ in selected ovarian cells from beagle bitches, using the potassium pyroantimonate (PPA) method. Samples were collected from 30 clinically healthy, pre-pubertal, genetically homogeneous animals. The bitches were divided into three groups of 10 animals each: experimental group I - 50 μg ZEN/kg BW (100% NOAEL) administered once daily per os; experimental group II - 75 μg ZEN/kg BW (150% NOAEL) administered once daily per os; control group - placebo containing no ZEN administered per os. An electron microscopic analysis revealed that cells died due to apoptosis, depending on the ZEN dose and the type of cells exposed to intoxication. Lower ZEN doses led to apoptosis-like changes in the cells. Cell death was a consequence of excess Ca2+ accumulation in the mitochondria, followed by cell dysfunction and a decrease in or the absence of mitochondrial metabolic activity in oocytes, follicle cells and interstitial cells in experimental bitches.

Effect of Calcium Nutrient on Calcium Distribution and Ultrastructure of Cell and Chloroplast in Bunching Onion Leaf

Effect of calcium nutrient on calcium distribution and ultrastructure of cell and chloroplast in Bunching Onion (Allium fistulosum L. var. caespitosum Makino) leaf was studied in sands with 4 Ca2+ treatments (0, 40, 80 and 160 mg/L ), in which the solution was Hoagland's. Localization and distribution of calcSuperscript textium and the influence of calcium nutrition on cell ultrastructure were observed by transmission electron microscopy combined with in situ precipitation of calcium with potassium pyroantimonate technique. The results showed that Ca2+ were mainly located in cell membrane, vacuoles, envelope of chloroplast and intercellular space in normal cells of bunching onion, however, Ca2+ was found to compartment in cytosol in large quantity, and the release of membrane-associated Ca2+ to cytosol and wall-associated Ca2+ to the intercellular spaces was observed in Ca-deficient leaves. In serious Ca-deficient leaves, Ca2+ quantities in cell decreased. Under Ca-deficiency, chloroplast membranes, plasma membranes and nuclear membranes were damaged, and cell walls disassociated, an enlarged space could be found between cells. In serious Ca-deficient leaves, cell compartmentation was destroyed, chloroplast deformed, plasma separated from cell wall, then whole cell constricted.

Microwave-induced fast decalcification of rat bone for electron microscopic analysis: an ultrastructural and cytochemical study

Bone decalcification is a time-consuming process. It takes weeks and preservation of the tissue structure depends on the quality and velocity of the demineralization process. In the present study, a decalcification methodology was adapted using microwaving to accelerate the decalcification of rat bone for electron microscopic analysis. The ultrastructure of the bone decalcified by microwave energy was observed. Wistar rats were perfused with paraformaldehyde and maxillary segments were removed and fixed in glutaraldehyde. Half of specimens were decalcified by conventional treatment with immersion in Warshawsky solution at 4ºC during 45 days, and the other half of specimens were placed into the beaker with 20 mL of the Warshawsky solution in ice bath and thereafter submitted to irradiation in a domestic microwave oven (700 maximum power) during 20 s/350 W/±37ºC. In the first day, the specimens were irradiated 9 times and stored at 40ºC overnight. In the second day, the specimens were irradiated 20 times changing the solution and the ice after each bath. After decalcification, some specimens were postfixed in osmium tetroxide and others in osmium tetroxide and potassium pyroantimonate. The specimens were observed under transmission electron microscopy. The results showed an increase in the decalcification rate in the specimens activated by microwaving and a reduction of total experiment time from 45 days in the conventional method to 48 hours in the microwave-aided method.

Calcium Distribution and Accumulation in Ovules of Plumbago Zeylanica

The embryo sac (ES) of Plumbago zeylanica, unlike most other flowering plants, lacks synergidsthe cell type that usually receives the pollen tube and the male gametes. Normally, synergids store copious amounts of calcium, estimated to exceed 15% by weight; this is believed to attract pollen tubes, which penetrate the ES, and may trigger the release of the sperm cells within one of the two synergids. If high concentrations of calcium are truly required for fertilization, the ES of Plumbago should also contain significant quantities. Synergids in normal flowering plants are preprogrammed for cell death, receiving the contents of the pollen tube directly in their cells, whereas synergid-lacking angiosperms apparently do not have such an apoptotic cell in the ES. Potassium pyroantimonate labeling was used to localize principally loosely-bound calcium, because it is a relatively mobile form of the Ca2+ ion that is available for redistribution during fertilization events.

Zonal heterogeneity of calcium distribution in rat hepatocytes: an electron microscopic study with a combined glutaraldehyde-osmium-pyroantimonate technique.

Potassium pyroantimonate in combination with osmium tetroxide is an excellent technique for investigation of the subcellular distribution of calcium ions in glutaraldehyde-fixed liver tissue. Under appropriate incubation conditions potassium ions are replaced by calcium ions to form an insoluble electron-dense calcium antimonate precipitate. The presence of calcium within this antimonate precipitate is confirmed by the electron spectroscopic imaging (ESI) technique. Chelator treatment with EGTA [ethylene glycol-bis-(beta-amino-ethyl ether) N',N',N'-tetraacetic acid] is usually used as a control, preventing the precipitation of calcium. In our investigation, computerized image analysis revealed a gradient of the calcium distribution from the periportal to the pericentral area. A finely dispersed precipitate was found in the mitochondrial matrix and in the euchromatin of the nuclei of the periportal hepatocytes, and in the organelles of the pericentral area a coarser deposit in lower concentration was recognized. Our findings indicate that periportal and pericentral hepatocytes retain their zonal characteristics also with respect to calcium concentration in mitochondria and nuclei.