Size exclusion chromatography of H-coal liquids on silica,polyvinylacetate and polystyrene columns

The physico-chemical properties of liquids derived from Kentucky coals have been examined using size exclusion chromatography. Three major types of column packing for s.e.c. have been used in the H-coal liquid analysis: inorganic silica particles commonly known as controlled pore glass, soft polyvinylacetate gel and a rigid polystyrene-divinylbenzene gel. Of these, the PVA column appears to be a general and versatile choice for routine s.e.c. analysis of coal-derived liquids.     

Cellular uptake, evolution, and excretion of silica nanoparticles in human cells

A systematic study on the interaction of silica nanoparticles (NPs) with human cells has been carried out in the present work. Endocytosis and exocytosis are identified as major pathways for NPs entering, and exiting the cells, respectively. Most of the NPs are found to be enclosed in membrane bounded organelles, which are fairly stable (against rupture) as very few NPs are released into the cytoplasm. The nanoparticle-cell interaction is a dynamic process, and the amount of NPs inside the cells is affected by both the amount and morphology (degree of aggregation) of NPs in the medium. These interaction characteristics determine the low cytotoxicity of SiO(2) NPs at low feeding concentration.     

Translocation and fate of multi-walled carbon nanotubes in vivo

Carbon nanotube (CNT) mediated delivery system of drugs etc. has currently aroused a large interest. Because the delivery system will be ultimately introduced into the human body, the information about the in vivo biological behavior and consequences of CNTs becomes very important. Here, using [¹⁴C-taurine]-multi-walled CNTs (MWCNTs) as tracers, we show the biodistribution and translocation pathways of MWCNTs in mice by three different routes. After mice were exposed by intravenous injection, MWCNTs predominately accumulated in liver and retained for long time. Transmission electron micrographs clearly show the remarkable entrapment of MWCNTs in hepatic macrophages (Kupffer cells). The biological index examinations indicate low liver acute toxicity of MWCNTs. Some favorable aspects of MWCNTs being used as a drug nanovehicle are also discussed.     

Chemical,biological, and antibacterial characterization of silica glass containing silver and gold nanoparticles

The aim of this study has been the preparation of sol‐gel glasses with potential antibacterial properties. Bioactive glasses containing different percentages of silver and gold nanoparticles have been synthesized via the sol‐gel method. The obtained glasses have 0.5, 1, 1.5, and 2 wt% silver as well as a constant amount of gold nanoparticles (AuNP) added as colloidal solution (15 wt%). Fourier Transform Infrared (FTIR) spectroscopy was used to characterize the materials. Scanning electron microscopy (SEM) has been used to investigate the surface of each sample. Moreover, the materials have been characterized in order to verify their antibacterial activities as well as their bioactivity and cytocompatibility as a function of Ag and Au content. SEM/EDX analysis has shown that the samples are bioactive because they are able to stimulate hydroxyapatite nucleation on their surface when soaked in a simulated body fluid (SBF). WST‐8 assay of 3T3 cells, placed in contact with the material extracts, has showed that the glass does not induce cytotoxicity. Staphylococcus epidermidis and Pseudomonas aeruginosa strains have been used for the evaluation of the antibacterial properties of each sample. The experimental data have shown that all synthesized materials have antibacterial activity. However, the two bacterial strains respond differently to the materials. The data show that the presence of AuNP causes a decrease in the antibacterial activity of Ag⁺ ions.     

Characteristics of the fate and efficiency of nitrogen in supergranules of urea

Using¹⁵ N tracer technique, the fate and efficiency of nitrogen in supergranules of urea as compared with that in powdered urea were studied in rice fields. The results obtained show that supergranules of urea were characterized by the slight N loss and high N recovery as well as by delayed but long lasting fertilization effects. It follows that the supergranules should be applied earlier and at a lower rate as compared with powdered urea.     

Phosphorus and potassium uptake,translocation, and utilization efficiency in chickpea under Mediterranean conditions

Nutrient Cycling in Agroecosystems - Sowing time and cultivar choice have major effects on chickpea yield in the Mediterranean climate, but the effects on nutrient requirements are not well known....     

The metabolic fate of cholesterol-5α,6α-epoxide in vivo

[¹⁴C] Cholesterol-5α,6α-epoxide, administered to mice by either gastric intubation or skin painting, was rapidly and primarily excreted in the feces. Residual amounts of the epoxide and its metabolites were found in a wide variety of organs, and persisted for at least 72 hr. At some sites (principally the liver, the small intestinal contents and the combined stomach/duodenum and their contents), the labeled compound existed in a water-soluble form which could not be extracted with chloroform/methanol. Treatment of the small intestinal contents with a preparation of β-glucuronidase/sulfatase produced a marked increase in the amount of organic-solvent-extractable cholesterol-α-epoxide and other polar metabolites. Unchanged epoxide was found mainly in the feces and the skin at the site of application. On the basis of these results, stool specimens, and not blood samples, should be analyzed to detect the presence of this compound and/or its metabolites in vivo.     

Mineral phase and structure changes during roasting of fine-grained carbonaceous gold ores and their effects on gold leaching efficiency

While roasting has been widely applied to reduce the negative effect of carbonaceous matters on gold extraction from fine-grained carbonaceous gold ores, the phase and structure changes of minerals during roasting and their influences on the leaching rate of gold have not been fully understood. This limits the extraction of carbonaceous gold deposits. The current work examines the oxidation process of a fine-grained carbonaceous gold ore during roasting using a range of techniques including X-ray diffraction(XRD), scanning electron microscopy(SEM),Energy Dispersive Spectrometer(EDS) analysis and pore structure analysis together with gold leaching tests.The results show that during the process of oxidative roasting, the carbonaceous matters(organic carbon and graphitic carbon) and pyrite were completely decomposed at 600 ℃ with the carbonaceous components burned and pyrite oxidized into hematite. At 650 ℃, while dolomite was decomposed into calcia, magnesia, calcium sulfate etc., the calcine structure became loose and porous, leading to a high gold leaching rate from the roasted product. Above 750 ℃, the porous calcite structure started to collapse along with the agglomeration, leading to the secondary encapsulation of gold particles, which contributed to the sharp drop in the gold leaching rate of the roasted product. This study suggests optimum phase and structure changes of minerals during roasting to achieve maximum gold extraction from fine-grained carbonaceous gold deposits.     

负载硅聚醚离子液体的制备及催化转化CO_2的应用

首先制备氯化1-羧基聚醚-3-甲基咪唑离子液体[HOOC-PECH-MIM]Cl,再将其与正硅酸乙酯(TEOS)反应制备负载硅聚醚离子液体催化剂(Si-[HOOC-PECH-MIM]Cl),采用红外光谱仪、热重分析仪和电镜扫描仪对其化学结构、热性能和表观形貌进行测试。然后用其催化转化二氧化碳(CO_2)合成碳酸丙烯酯。研究温度、压力、催化剂用量等因素对转化率和选择性的影响。结果表明,负载硅聚醚离子液体制备成功,实现了相态转变,且具有较高的热稳定性。在较温和条件下即可高效完成催化过程,活性高、选择性好。当催化温度为90℃,压力为1.8 MPa,用量为2.5%时,转化率和选择性分别为100%和97.2%。     

负载硅聚醚离子液体的制备及催化转化CO_2的应用

首先制备氯化1-羧基聚醚-3-甲基咪唑离子液体[HOOC-PECH-MIM]Cl,再将其与正硅酸乙酯(TEOS)反应制备负载硅聚醚离子液体催化剂(Si-[HOOC-PECH-MIM]Cl),采用红外光谱仪、热重分析仪和电镜扫描仪对其化学结构、热性能和表观形貌进行测试。然后用其催化转化二氧化碳(CO_2)合成碳酸丙烯酯。研究温度、压力、催化剂用量等因素对转化率和选择性的影响。结果表明,负载硅聚醚离子液体制备成功,实现了相态转变,且具有较高的热稳定性。在较温和条件下即可高效完成催化过程,活性高、选择性好。当催化温度为90℃,压力为1.8 MPa,用量为2.5%时,转化率和选择性分别为100%和97.2%。     

Effect of surface properties of silica nanoparticles on their cytotoxicity and cellular distribution in murine macrophages

In this study, complexes composed of poly-l-tyrosine (pLT) and single-walled carbon nanotubes (SWCNTs) were produced and the dispersibility of the pLT/SWCNT complexes in water by measuring the ζ potential of the complexes and the turbidity of the solution were investigated. It is found that the absolute value of the ζ potential of the pLT/SWCNT complexes is as high as that of SWCNTs modified with double-stranded DNA (dsDNA) and that the complexes remain stably dispersed in the water at least for two weeks. Thermogravimetry analysis (TGA) and visualization of the surface structures of pLT/SWCNT complexes using an atomic force microscope (AFM) were also carried out.     

Effect of surface properties of silica nanoparticles on their cytotoxicity and cellular distribution in murine macrophages

Surface properties are often hypothesized to be important factors in the development of safer forms of nanomaterials (NMs). However, the results obtained from studying the cellular responses to NMs are often contradictory. Hence, the aim of this study was to investigate the relationship between the surface properties of silica nanoparticles and their cytotoxicity against a murine macrophage cell line (RAW264.7). The surface of the silica nanoparticles was either unmodified (nSP70) or modified with amine (nSP70-N) or carboxyl groups (nSP70-C). First, the properties of the silica nanoparticles were characterized. RAW264.7 cells were then exposed to nSP70, nSP70-N, or nSP70-C, and any cytotoxic effects were monitored by analyzing DNA synthesis. The results of this study show that nSP70-N and nSP70-C have a smaller effect on DNA synthesis activity by comparison to unmodified nSP70. Analysis of the intracellular localization of the silica nanoparticles revealed that nSP70 had penetrated into the nucleus, whereas nSP70-N and nSP70-C showed no nuclear localization. These results suggest that intracellular localization is a critical factor underlying the cytotoxicity of these silica nanoparticles. Thus, the surface properties of silica nanoparticles play an important role in determining their safety. Our results suggest that optimization of the surface characteristics of silica nanoparticles will contribute to the development of safer forms of NMs.     

Impact of the guanidinium group on hybridization and cellular uptake of cationic oligonucleotides

The grafting of cationic groups to synthetic oligonucleotides (ONs) in order to reduce the charge repulsion between the negatively charged strands of a duplex or triplex, and consequently to increase a complex's stability, has been extensively studied. Guanidinium groups, which are highly basic and positively charged over a wide pH range, could be an efficient ON modification to enhance their affinity for nucleic acid targets and to improve cellular uptake. A straightforward post-synthesis method to convert amino functions attached to ONs (on sugar, nucleobase or backbone) into guanidinium tethers has been perfected. In comparison to amino groups, such cationic groups anchored to alpha-oligonucleotide phosphoramidate backbones play important roles in duplex stability, particularly with RNA targets. This high affinity could be explained by dual recognition resulting from Watson-Crick or Hoogsteen base pairing combined with cationic/anionic backbone recognition between strands involving H-bond formation and salt bridging. Molecular-dynamics simulations corroborate interactions between the cationic backbones of the alpha-ONs and the anionic backbones of the nucleic acid targets. Moreover, ONs with guanidinium modification increased cellular uptake relative to negatively charged ONs. The cellular localization of these new cationic phosphoramidate ONs is mainly cytoplasmic. The uptake of these ON analogues might occur through endocytosis.     

The effect of gas pressure on NO conversion energy efficiency in nonthermal nitrogen plasma

This work explores the effect of gas pressure on the rate of electron collision reactions and energy consumption for NO conversion in N₂ in a pulsed corona discharge reactor. A previous study showed that the rate constant of electron collision reactions, multiplied by the electron concentration, can be expressed as . The model parameter α remains constant with increasing gas pressure, which verifies the previous assumption that the electron temperature is inversely proportional to gas pressure. However, the model parameter β decreases with increasing gas pressure, which indicates that the rate constant of electron collision reactions decreases with increasing gas pressure. The new expression for the rate constant of electron collision reactions, , is more general because it explicitly accounts for the effect of gas pressure that was previously contained in the parameter β. The electron mean energy decreases with increasing gas pressure, which results in thermal dissipation of a larger fraction of the energy input to the reactor that heats the gas instead of producing plasma chemical reactions. Therefore, energy efficiency for NO conversion in N₂ decreases with increasing gas pressure.     

Effect of dietary docosahexaenoic acid on desaturation and uptake in vivo of isotope-labeled oleic, linoleic, and linolenic acids by male subjects

The effect of dietary docosahexaenoic acid (22∶6n−3, DHA) on the metabolism of oleic, linoleic, and linolenic acids was investigated in male subjects (n=6) confined to a metabolic unit and fed diets containing 6.5 or <0.1 g/d of DHA for 90 d. At the end of the diet period, the subjects were fed a mixture of deuterated triglycerides containing 18∶1n−9[d6], 18∶2n−6[d2], and 18∶3n−3[d4]. Blood samples were drawn at 0, 2, 4, 6, 8, 12, 24, 48, and 72 h. Methyl esters of plasma total lipids, triglycerides, phospholipids, and cholesterol esters were analyzed by gas chromatography-mass spectrometry. Chylomicron triglyceride results show that the deuterated fatty acids were equally well absorbed and diet did not influence absorption. Compared to the low-DHA diet (LO-DHA), clearance of the labeled fatty acids from chylomicron triglycerides was modestly higher for subjects fed the high DHA diet (HI-DHA). DHA supplementation significantly reduced the concentrations of most n-6[d2] and n-3[d4] long-chain fatty acid (LCFA) metabolites in plasma lipids. Accumulation of 20∶5n−3[d4] and 22∶6n−3[d4] was depressed by 76 and 88%, respectively. Accumulations of 20∶3n−6[d2] and 20∶4n−6[d2] were both decreased by 72%. No effect of diet was observed on acyltransferase selectivity or on uptake and clearance of 18∶1n−9[d6], 18∶2n−6[d2], and 18∶3n−3[d4]. The results indicate that accumulation of n−3 LCFA metabolites synthesized from 18∶3n−3 in typical U.S. diets would be reduced from about 120 to 30 mg/d by supplementation with 6.5 g/d of DHA. Accumulation of n−6 LCFA metabolites synthesized from 18∶2n−6 in U.S. diets is estimated to be reduced from about 800 to 180 mg/d. This decrease is two to three times the amount of n−6 LCFA in a typical U.S. diet. These results support the hypothesis that health benefits associated with DHA supplementation are the combined result of reduced accretion of n−6 LCFA metabolites and an increase in n−3 LCFA levels in tissue lipids.     

The effect of various phosphorus fertilizers on yields,phosphorus uptake by plants and conversion of phosphorus fertilizers in long-term experiments on different soils

Long-term experiments have been undertaken to investigate the effects of various types of phosphorus fertilizers on yields, phosphorus uptake and fertilizer conversion in the soil. Optimum effects were obtained from water-soluble phosphate, whereas finely ground soft rock phosphate had little effect even with large amounts of phosphorus fertilizers and with a pH value of the soil of around 5.4. Partially decomposed and sintered phosphates performed well, as did NPK fertilizers (100% water soluble) and Thomas phosphate. The addition of large amounts of phosphorus fertilizers (to cereals, 26.4 kg/ha, to other crops 44 kg/ha) led to yields being increased by 7% and phosphorus extraction being increased by 11%. Smaller amounts of phosphorus fertilizers (13.2 and 17.6 kg/ha) did not have this effect. Increases in the amount of double-lactate-soluble phosphorus in the soil depended on the level of fertilization and did not differ significantly according to the type of phosphorus fertilizer used.     

Adsorption of biomolecules on mesostructured cellular foam silica: Effect of acid concentration and aging time in synthesis

Mesostructured cellular foam (MCF) silica was synthesized using a non-ionic surfactant template-directed method without ammonium fluoride; the acid concentration and aging time were varied to determine the effects of these parameters on the final material. Increasing the acid concentration and aging time resulted in larger window size, which is critical in gating of biomolecule access to the interior of the MCF silica. In particular, when the acid concentration was changed from 1.6 to 3.5 M the window pore dimension approximately doubled, although the pore size distribution was broader. In this study, the optimal synthesis conditions to produce large, narrowly distributed window pores are 3.5 M HCl with an aging time of 20 h. The loadings of l-tryptophan (Trp), lysozyme (LYS) and bovine serum albumin (BSA) on the MCF samples were measured using batch adsorption. Adsorption data followed a Type I isotherm. The monolayer adsorption capacity of Trp on acid-washed MCF was several times higher than that of LYS and BSA, because of the smaller size of Trp. Protein adsorption onto MCF silica showed minimal size exclusion until the window size of the silica was barely larger than the largest protein dimension.     

Neutral AuCl complexes supported in linear high molecular weight, poly-spirophosphazene-phosphine copolymers and its conversion to nanostructured gold materials

Summary The reaction under very mild conditions of the polyspirophosphazene copolymer with pendant diphenylphosphine groups {[NP(O₂C₁₂H₈)]_0.85[NP(OC₆H₄PPh₂)₂]_0.15}_n (I) (O₂C₁₂H₈= 2,2’-dioxybiphenyl) with [Au(THT)Cl] (THT = tetrahydrothiophene) gives the neutral polymeric complex {[NP(O₂C₁₂H₈)]_0.85[NP(OC₆H₄PPh₂-AuCl)₂]_0.15}_n (II). The new material has been characterized by spectrocopic and thermochemical methods (TGA and DSC). Pyrolysis of the Au polymer (I) in air at 800 °C gave gold nanostructured materials that were characterized by TEM, SEM-EDAX and X-ray diffraction. Nanoparticles in the range of 90 to 130 nm were seen. Dedicated to Professor Victor Riera, Departamento de Quimica Orgánica e Inorgánica, Universidad de Oviedo, Spain, on the occasion of his 70^thbirthday.     

The influence of tetrapod-like ZnO morphology and electrolytes on energy conversion efficiency of dye-sensitized solar cells

Tetrapod-like ZnO nanostructures prepared by dc plasma technology were used as photoelectrodes in dye-sensitized solar cells (DSSCs). Each of the tetrapod-like ZnO possesses four extended arms that offer improved electron transport properties. Tetrapod-like ZnO with short (S-ZnO) and long arms (L-ZnO) were synthesized by controlling the plasma gas flow and the input power. Between these two tetrapod-like ZnO nanopowders, the DSSCs using S-ZnO showed higher energy conversion efficiency than using L-ZnO. This is due to the resulting increase in dye adsorption and enhanced short-circuit current density, using S-ZnO. Electrochemical impedance spectroscopy (EIS) shows that the properties of electron transport of S-ZnO are superior to that of the L-ZnO. We investigated the effect of the redox electrolytes (I₂) and the additives (LiI and TBP) on the performance of the DSSCs by intensity-modulated photovoltage spectroscopy and EIS.     

Fabrication of inorganic/polymer nanocomposite membranes containing very high silica content via in situ surface grafting reaction and reactive dispersion of silica nanoparticles: Proton conduction,water uptake,and oxidative stability

In this study, we present a new fabrication process for proton exchange membranes based on inorganic/organic nanocomposite using in situ surface grafting reaction and reactive dispersion of silica nanoparticles in the presence of reactive dispersant, urethane acrylate nonionomer (UAN). Through in situ surface grafting reaction of silica nanoparticles, urethane acrylates were chemically introduced on the surface of silica nanoparticles, which were dispersed in DMSO solutions containing UAN and sodium styrene sulfonate (NaSS). After urethane linkage and copolymerization of NaSS, UAN and urethane acrylate moieties of silica nanoparticles, the solutions were converted to silica nanoparticle‐dispersed proton exchange membranes where silica particles were chemically connected with organic polymer chains. 5.89–29.45 wt % of silica nanoparticles could be dispersed and incorporated in polymer membranes, which were confirmed by transmittance electron microscopy (TEM) measurement. On varying weight % of silica nanoparticles dispersed within the membranes, water uptake and oxidative stability of nanocomposite membranes were largely changed, but membranes showed almost the same proton conductivity (greater than 10⁻² S cm⁻¹). At 5.89 wt % of silica nanoparticles, nanocomposite membranes showed the lowest water uptake and excellent oxidative stability compared to the sulfonated polyimide membranes fabricated by us. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011