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PubMed2006

Two polymorphs of potassium trichloro[diethyl (methylsulfinylmethyl)phosphonate-kappaS]platinum(II) with Z' = 1 and 3 in the space group P2(1)2(1)2(1).

Two new polymorphs of the title compound, K[PtCl(3)(C(6)H(15)O(4)PS)], already known in the monoclinic form, were obtained by crystallization from acetone-n-pentane solutions of different composition. Both polymorphs are orthorhombic in the space group P2(1)2(1)2(1), with Z' = 1 (solvent ratio 1:4) and 3 (solvent ratio 1:9). In both polymorphs, electrostatic interactions link K(+) cations and [PtCl(3)(SMP)](-) anions [SMP is diethyl (methylsulfinylmethyl)phosphonate] in infinite chains, while adjacent chains are held together by weak C-H...Cl and C-H...O hydrogen-bond interactions.

Molecular Structure↗
PubMed1989

Three potassium currents in mouse motor nerve terminals.

A study of the K conductance of the presynaptic membrane has been performed in the triangularis sterni muscle of the mouse. External currents generated in the presynaptic terminals upon invasion by action potentials have been recorded using microelectrodes inserted into the perineurium of preterminal nerve bundles. The voltage-dependent K current could be pharmacologically dissected into fast (IKf) and slow (IKs) components. While both are sensitive to 3,4-diaminopyridine (3,4-DAP), only IKf is sensitive to tetraethylammonium (TEA). Uranyl (100-200 microM) and guanidine (5-10 mM) produced a near complete block of IKf and IKs, which can explain their facilitatory effect upon transmitter release. The third K current of presynaptic terminals is Ca2+-dependent, but was activated also by Sr2+. This current could be suppressed by nanomolar doses of charybdotoxin; it is also sensitive to TEA but not to 3,4-DAP, uranyl or guanidine.

4-Aminopyridine↗
PubMed2003

Effect of alkaline treatment of pure titanium and its alloys on the bonding strength of dental veneering resins.

Commercially pure titanium (cpTi), Ti6Al4V, an experimental beta-type titanium (Ti 53.4 wt%, Nb 29 wt %, Ta 13 wt %, and Zr 4.6 wt %), and 12% AuPdAg alloy plates were sandblasted, cleaned in water, and dried. cpTi plates were treated with nine alkaline treatments that differed in the type of alkali, alkaline concentration, soaking temperature, soaking time, and heating temperature. cpTi plates that were only sandblasted or sandblasted and oxidized at 600 degrees C for 1 h in air were also prepared. Finally, the bonding strengths of 11 kinds of surface-treated cpTi to resin were measured using a pull-shear bonding method after immersion in physiologic saline solution at 37 degrees C for 24 h. The bonds of the standard alkaline-treated cpTi and two titanium alloys to resins were 1.5-1.9 times stronger than those of sandblasted specimens (p < 0.01), but no significant effects of the alkaline treatment were observed on the 12% AuPdAg alloy. The greatest bonding strengths were found for cpTi treated with NaOH and KOH and then heated at 600 degrees C (p < 0.01). In conclusion, alkaline treatment is a simple, effective surface modification of titanium that improves bonding to veneering resin.

Alloys↗
PubMed2005

New biodegradable amphiphilic block copolymers of epsilon-caprolactone and delta-valerolactone catalyzed by novel aluminum metal complexes. II. Micellization and solution to gel transition.

In our previous study [J. Yang, L. Jia, L. Yin, J. Yu, Z. Shi, Q. Fang, A. Cao, Macromol. Biosci. 2004, 4, 1092.], new biodegradable copolymers of diblock methoxy poly(ethylene glycol)-block-poly(epsilon-caprolactone) and methoxy poly(ethylene glycol)-block-poly(delta-valerolactone), and triblock poly(epsilon-caprolactone)-block-poly(ethylene glycol)-block-poly(epsilon-caprolactone) and poly(delta-valerolactone)-block-poly(ethylene glycol)-block-poly(delta-valero-lactone) bearing narrow molecular weight distributions and well-defined block architectures were reported to be prepared with our original aluminum metal complex templates. This work will continue to report new investigations on their water solubility, and reversible thermal responsive micellization and solution to gel transition in distilled water. Among the new synthesized copolymers (P1-P23), seven diblock or triblock samples (P3, P6, P7, P11, P12, P19, and P21) with higher hydrophilic building block populations were revealed to be water soluble under ambient temperature. By means of UV spectrophotometer attached with a thermostat, important parameters as critical micellization mass concentrations (CMCs) and critical micellization temperatures (CMTs) were characterized for these new amphiphile dilute aqueous solution with the aid of an lipophilic organic dye probe of 1,6-diphenyl-1,3,5-hexatriene (DPH). Furthermore, the critical gelation temperatures (CGTs) were simultaneously investigated for these water-soluble block copolymers via a tube tilting method. It was found that the CMC, CMT, and CGT were strongly affected by the population and nature of the hydrophobic building blocks, and a higher hydrophobicity of the new amphiphilic block copolymer finally led to lower CMC and CMT, and higher CGT. In addition, the salts of KBr and NaCl were found to play as a salt-out effect on the solution to gel transition for the diblock P6 and triblock P11, exhibiting an interesting tunable gelation temperature close to 35-42 degrees C. These results will pave new possibility for the synthesized block structural amphiphiles as potential biomaterials to be applied in vivo.

Alum Compounds↗
PubMed2006

Kinetics and equilibrium studies for the adsorption of Acid Red 57 from aqueous solutions onto calcined-alunite.

The adsorption of Acid Red 57 (AR57) onto calcined-alunite was examined in aqueous solution in a batch system with respect to contact time, pH and temperature. The first-order, pseudo-second-order kinetic and the intraparticle diffusion models were used to describe the kinetic data and the rate constants were evaluated. The experimental data fitted very well the pseudo-second-order kinetic model and also followed the intraparticle diffusion model up to 90 min. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were also determined. The equilibrium data are successfully fitted to the Langmuir adsorption isotherm. The Langmuir isotherm constant, K(L), was used to evaluate the changes of free energy, enthalpy and entropy of adsorption for the adsorption of AR57 onto calcined-alunite. The results indicate that calcined-alunite could be employed as low-cost material for the removal of acid dyes from textile effluents.

Adsorption↗
PubMed2006

Two simplified fluorescent staining techniques to observe infection structures of the oomycete Plasmopara viticola in grapevine leaf tissues.

Plasmopara viticola, the causal agent of grapevine downy mildew, is an obligate biotrophic oomycete that grows in the intercellular spaces of host tissues and develops haustoria in the cells. Histological observations are the most effective methods to visualize and quantify the development of the infection structures. We chose two staining techniques leading to high resolution and contrast between parasite structures and host-plant tissues with a minimum of sample preparation: Blankophor and KOH-aniline blue fluorescent stainings. Blankophor (50 ppm in water or 15% KOH) staining was used to study the zoospore encystement on the leaf surface after release from sporangia. The aniline blue dye (0.05% in 0.067 M K(2)HPO(4), pH 9-9.5, after hot KOH whitening) was used to observe the invasive structures inside host tissues that lead to the production of sporangiophores and infectious sporangia. We tested modifications of some parameters of the procedures to determine the most appropriate for high throughput analyses adapted to our pathosystem and equipment facilities.

Aniline Compounds↗
PubMed2001

Optimization of submerged culture conditions for the mycelial growth and exo-biopolymer production by Cordyceps militaris.

AIMS: The objective of the present study was to determine the optimal culture conditions for exo-biopolymer production by Cordyceps militaris in shake flask culture. METHODS AND RESULTS: The optimal temperature and initial pH for both mycelial growth and exo-biopolymer production by Cordyceps militaris in shake flask culture were found to be 20 degrees C and 6.0, respectively. Sucrose (40 g x l(-1)) and corn steep powder (10 g x l(-1)) were the most suitable carbon and nitrogen source for both mycelial growth and exo-biopolymer production. CONCLUSION: Under optimal culture conditions, the maximum exo-biopolymer concentration in a 5-l jar fermenter indicated 10.3 g x l(-1), which was approximately three times higher than that in shake flask culture. SIGNIFICANCE AND IMPACT OF THE STUDY: This process can have a significant impact on the industrial scale when sucrose and corn steep powder were used as carbon and nitrogen source.

Carbon↗
PubMed1999

Identification of a GABAB receptor subunit, gb2, required for functional GABAB receptor activity.

G protein-coupled receptors are commonly thought to bind their cognate ligands and elicit functional responses primarily as monomeric receptors. In studying the recombinant gamma-aminobutyric acid, type B (GABAB) receptor (gb1a) and a GABAB-like orphan receptor (gb2), we observed that both receptors are functionally inactive when expressed individually in multiple heterologous systems. Characterization of the tissue distribution of each of the receptors by in situ hybridization histochemistry in rat brain revealed co-localization of gb1 and gb2 transcripts in many brain regions, suggesting the hypothesis that gb1 and gb2 may interact in vivo. In three established functional systems (inwardly rectifying K+ channel currents in Xenopus oocytes, melanophore pigment aggregation, and direct cAMP measurements in HEK-293 cells), GABA mediated a functional response in cells coexpressing gb1a and gb2 but not in cells expressing either receptor individually. This GABA activity could be blocked with the GABAB receptor antagonist CGP71872. In COS-7 cells coexpressing gb1a and gb2 receptors, co-immunoprecipitation of gb1a and gb2 receptors was demonstrated, indicating that gb1a and gb2 act as subunits in the formation of a functional GABAB receptor.

Amino Acid Sequence↗
PubMed1995

Factors affecting the concentration of compound A resulting from the degradation of sevoflurane by soda lime and Baralyme in a standard anesthetic circuit.

Carbon dioxide absorbents, such as soda lime and Baralyme brand absorbent, convert sevoflurane to CF2 = C(CF3)OCH2F, a vinyl ether called "Compound A," whose toxicity raises concerns regarding the safety of sevoflurane in rebreathing circuits. Because an increased inflow rate to an anesthetic circuit decreases rebreathing, we assumed that an increased rate would proportionately decrease the concentration of Compound A. In the present report, we measured the Compound A concentration resulting from the action of wet (standard) soda lime and wet (standard) Baralyme on 2% sevoflurane in a model anesthetic circuit, using inflow rates (0.5, 1.0, 2.0, 4.0, and 6.0 L/min), ventilations (5 and 10 L/min), and carbon dioxide production/removal (200 and 400 mL/min) found in clinical practice. An increase in inflow rate decreased Compound A concentration to lower levels as inflow rate approached minute ventilation. At lower inflow rates, increasing duration of sevoflurane inflow increased the concentration of Compound A, a finding consistent with a progressive increase in absorbent temperature from absorption of carbon dioxide and consequently greater sevoflurane degradation. There was no material difference between Baralyme and soda lime in the concentrations of Compound A produced at a particular inflow rate. An increase in ventilation increased the concentration of Compound A, having a much greater effect at high rather than low inflow rates. An increase in amount of carbon dioxide absorbed also increased the concentration of Compound A. We conclude that inflow rate, ventilation, and carbon dioxide production are major determinants of the concentration of Compound A.

Absorption↗
PubMed1981

Effect of nitrate on reduction of ferric iron by a bacterium isolated from crude oil.

A Pseudomonas sp. isolated from crude oil reduced ferric ions (Fe(III)) to ferrous ions (Fe(II)). In the presence of nitrate (NO3-) after prolonged incubation, the amount of Fe(II) was lower than in its absence. However, during short incubation periods, the presence of NO3- significantly increased (99.5% confidence limit) the amount of Fe(II) produced. The decrease in Fe(II) on prolonged incubation was associated with increased production and accumulation of nitrite (NO2-). Under low NO3- levels, where the production of NO2- was limited, a decrease in NO2- concentration was accompanied by an increase in Fe(II) production to levels comparable with those obtained in the absence of NO3-. Preinduction of cells for nitrate reductase, which favoured rapid NO2- production, resulted in a more rapid decrease in Fe(II) production than in cells that were not preinduced. It is proposed that the inhibitory effect of NO3- on microbial reduction of Fe(III) is due to a secondary reaction, which involves the chemical oxidation of Fe(II) by NO2-.

Ferric Compounds↗
PubMed1990

A synthetic, selective culture medium for Pseudomonas aeruginosa.

Selective and differentiating media consisting of simple chemical components have been developed, both in solid and in liquid form, for culturing Pseudomonas aeruginosa from foodstuffs. These media work on the basic principle that Gram-negative bacteria can utilize ammonia as inorganic nitrogen source. This principle has already been utilized for developing a culture medium for coliform bacteria (Szita and Biró, 1986; Szita et al., 1988). P. aeruginosa can produce the ammonia needed for its growth by decomposing acetamide. The liquid synthetic medium was compared with the nitrofurantoin broth and the solid one with cetrimide agar by parallel inoculation of 60 raw milk samples and 20 P. aeruginosa pure cultures. The main advantages of the synthetic media are their high selectivity, high sensitivity and rapidity. Owing to their advantageous properties, the new media can be recommended for replacing cetrimide agar and nitrofurantoin broth.

Acetamides↗
PubMed1994

CO2 binding by Baralyme in three different carrier gases.

The absorptive properties of Baralyme and Sodasorb for CO2 in a container were studied by measuring the lifetime T0.5 of the unit, i.e., the time until the exit concentration of CO2 reaches 0.5%. The container size, the inlet gas flow rate, and the inlet CO2 concentration were varied. The experiments were repeated with either He, N2, or SF6 as the inert gas to evaluate the effect of increased gas density due to hyperbaric conditions on scrubber performance. It was found that T0.5 is best described by an exponential function of the type b (ttr)a, where ttr is the transit time of the gas through the container. The exponent a equals about 1.5 and varies relatively little. The constant b, however, is strongly dependent on inert gas density and on CO2 concentration in the inlet gas; it is independent of container size and gas flow rate. In addition, the amount of absorber reaching up to time T0.5 was measured in all conditions. It is strongly dependent on CO2 concentration; however, surprisingly it is nearly independent of inert gas properties. These results are compared with a mathematical model of scrubber behavior that is based on the chemical reaction rate of an imaginary absorber. The model neglects possible effects of CO2 diffusion in the gas phase, of ash formation, and of heat produced by the reaction. Differences between our experimental data and the model are analyzed as a function of these effects. The results give some simple predictive equations for the lifetime and the amount of absorber reacting.

Barium Compounds↗
PubMed1994

Reflection contrast microscopy within chrome-alum haematoxylin stained thick tissue-sections.

This paper introduces two innovations in reflection contrast microscopy (RCM): (1) an extended application for qualitative light microscopic investigations; and (2) a novel method for quantification in cytochemistry. (1) We found out that RCM cannot only be used for surface characterizations and in thin sections but also within thick tissue-sections. The use of the RCM technique is demonstrated on slides of the supraoptic nucleus (SON) of the rat stained with chrome-alum haematoxylin: Among all the stained structures only neurosecretory granules are found to cause reflections. The visualization of the neurosecretion and its distribution is more distinct and of sharper contrast than in bright field microscopy. (2) The improved differentiation allows the quantification of neurosecretion in tissue-sections by combining RCM with grey-scale image analysis.

Animals↗
PubMed2006

A practical and green approach toward synthesis of N3-substituted dihydropyrimidinones: using Aza-Michael addition reaction catalyzed by KF/Al2O3.

A simple and efficient method for the synthesis of N3-substituted 3,4-dihydropyrimidinones by aza-Michael addition reactions of 3,4-dihydropyrimidinones to alpha,beta-ethylenic compounds catalyzed by KF/Al(2)O(3) is described. The advantage of this method is high regioselectivity, high purity, and the use of a cheaper, milder, and efficient catalyst for the hetero-Michael addition reaction.

Aluminum Oxide↗
PubMed1994

Long-duration, low-flow sevoflurane anesthesia using two carbon dioxide absorbents. Quantification of degradation products in the circuit.

BACKGROUND: Sevoflurane reacts with soda lime, generating degradation products. The concentrations of sevoflurane degradation products in a low-flow circuit have been reported for anesthesia times of less than 5 h. In this study, sevoflurane degradation products generated during low-flow anesthesia exceeding 10 h were examined. METHODS: Sixteen patients received sevoflurane anesthesia with a fresh gas flow rate of 11/min. In eight patients, soda lime was used as the CO2 absorbent; in the other eight patients, Baralyme was used. During anesthesia, the concentrations of degradation products in the circuit, the temperature of the CO2 absorbent, inspired and end-tidal sevoflurane concentrations, and the volume of CO2 eliminated by the patient were measured. Gas was sampled from the inspiratory limb of the circuit and analyzed by gas chromatography. RESULTS: Two degradation products, CF2 = C(CF3)-O-CH2F (compound A) and CH3OCF2CH(CF3)OCH2F (compound B), were detected. In the soda lime group, the individual maximum concentration of compound A was 23.6 +/- 2.9 (12.0-37.4) ppm. In the Baralyme group, the concentration was 32.0 +/- 2.3 (23.5-41.3) ppm. The individual maximum concentration of compound A in the Baralyme group was significant higher than A in the Baralyme group was significant higher than that in the soda lime group. Compound B was detected in two patients, reaching a maximum concentration of 0.2 ppm. The end-tidal sevoflurane concentration, temperature of the CO2 absorbent, and volume of CO2 eliminated by the patient were the same in both groups. CONCLUSIONS: The degradation products detected were at low concentrations in long-duration, low-flow anesthesia with sevoflurane. Baralyme produced higher concentrations of degradation products than soda lime.

Adsorption↗