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PubMed2005

Adsorbent obtained from CEPT sludge in wastewater chemically enhanced treatment.

Chemically enhanced primary treatment (CEPT) in municipal wastewater treatment is particularly suitable for rapidly growing cities. The focus on CEPT process now might be the cost of chemicals and disposal of chemical sludge. In this study, the potential application of adsorbent made from CEPT sludge in CEPT wastewater treatment was investigated in various conditions, such as the adsorbent dosage, pH, and dosing modes of ferric chloride and adsorbent. It was found that sludge-derived adsorbent was a good way of sludge disposal while enhanced pollutants removal rate and reduced the fresh ferric chloride dosage. With the use of 10.0 mg L(-1) of ferric chloride and 0.6 g L(-1) of the adsorbent at the first stage simultaneously, the enhanced removal efficiencies of turbidity, UV254, COD, TP were 83.3%, 52.3%, 48.8% and 89.0%, respectively. The experiments showed that ferric chloride dose was reduced about 50%. The pH played a significant role in coagulation and adsorption process.

Adsorption↗
PubMed2004

Inverse metabolic engineering with phosphagen kinase systems improves the cellular energy state.

Inverse metabolic engineering attempts to identify or construct desired phenotypes of applied interest to endow them on appropriate host organisms. A particular desirable phenotype is the ATP homeostasis exhibited by animal cells with high and variable ATP turnover through temporal and spatial energy buffering. This buffering is achieved by phosphagen kinase systems that consist of a specific kinase and its cognate phosphagen, which functions as a large pool of 'high-energy phosphates' that are used to replenish ATP during periods of high energetic demand. This review discusses recent advances and potentials of inverse metabolic engineering of cell types that do not normally contain such systems--bacteria, yeast, plants, and liver--with creatine or arginine kinase systems. Examples are discussed that illustrate how microbial metabolism can be tailored for large-scale industrial processes with imperfect mixing and how the liver can be protected from metabolic insults or stimulated for better regeneration.

Adenosine Triphosphate↗
PubMed2002

Determination of platinated purines in oligoribonucleotides by limited digestion with ribonucleases T1 and U2.

Platinum complexes which are known to react preferentially with guanine (G) and adenine (A) bases of oligonucleotides can be used as tools to analyze their tertiary structures and eventually to cross-link them. However, this requires efficient methods to allow the identification and quantification of the corresponding adducts which have so far been developed only for oligodeoxyribonucleotides. Maxam-Gilbert type digestions cannot be used for RNAs and HPLC techniques would require too large amounts of expensive material for separation and further characterization. We report a method to determine platination sites on oligoribonucleotides based on the cleavage activity of ribonucleases T1 and U2. To test the method, these enzymes were first used under conditions of limited digestion on 5-mer oligoribonucleotides platinated at a single defined purine. The phosphodiester bond on the 3' side of platinated G or A appeared fully resistant to cleavage by ribonuclease T1 or U2, respectively. An inhibitory effect was also observed due to neighboring platinated purines, which decreases with their distance (-2, -1, +1, +2) from the cleavage site and with the enzyme concentration. The method allowed the identification and quantification of the platination sites of a 17-mer oligoribonucleotide, based on the analysis of the mixture of monoplatinated adducts.

Aspergillus oryzae↗
PubMed1999

Structural studies of the O-antigen polysaccharide from the enteroinvasive Escherichia coli O173.

The structure of the O-antigen polysaccharide (PS) from Escherichia coli O173 has been investigated. Sugar and methylation analyses, electrospray ionisation mass spectrometry together with 1H, 31P and 13C NMR spectroscopy were the main methods used. The structure of the pentasaccharide repeating unit of the PS was found to be: [formula: see text] By treatment with 48% HF the phosphoric diester linkage was cleaved together with the glycosidic linkage of the fucosyl group, rendering a tetrasaccharide with the structure: alpha-D-Glcp-(1-->2)-beta-D-Glcp-(1-->3)-beta-D-GlcpNAc-(1-->3)-D-Glc.

Animals↗
PubMed1986

The adsorption of polyaromatic hydrocarbons on natural and chemically modified asbestos fibers.

Many reports indicate that the carcinogenic (genotoxic) potential of benzo[a]pyrene (B[a]P) may be enhanced several-fold by the promoter (epigenetic) effect of asbestos particles. This promoting effect could be related to the fact that when B[a]P is adsorbed onto the particles, there is a resulting enhanced transport and uptake of the carcinogen into microsomial membranes. These in vitro data bear relevance to the epidemiological studies which indicate an association between exposure to inhaled asbestos dusts and the high incidence of pulmonary cancers in smokers. Using HPLC, it has been observed that B[a]P has great affinity for natural asbestos fibers, and that chemical modification of natural chrysotile with POCl3 results in the complete loss of this adsorption potential of chrysotile for benzo[a]pyrene.

Adsorption↗
PubMed2000

31P-CP-MAS NMR studies on TPP+ bound to the ion-coupled multidrug transport protein EmrE.

The binding of tetraphenylphosphonium (TPP+) to EmrE, a membrane-bound, 110 residue Escherichia coli multidrug transport protein, has been observed by 31P cross-polarisation-magic-angle spinning nuclear magnetic resonance spectroscopy (CP-MAS NMR). EmrE has been reconstituted into dimyristoyl phosphatidylcholine bilayers. CP-MAS could selectively distinguish binding of TPP+ to EmrE in the fluid membrane. A population of bound ligand appears shifted 4 ppm to lower frequency compared to free ligand in solution, which suggests a rather direct and specific type of interaction of the ligand with the protein. This is also supported by the observed restricted motion of the bound ligand. The observation of another weakly bound substrate population arises from ligand binding to negatively charged residues in the protein loop regions.

Amino Acid Sequence↗
PubMed2001

Studies on the response mechanism of thermionic detection to organophosphorus compounds.

The response of thermionic/nitrogen-phosphorus detection (TID) to a series of organophosphonate esters has been studied. The response of TID is found to decrease with the increase in the alkyl chain length of the molecules. An attempt has been made to propose the response mechanism of TID for these compounds. The charge carriers accountable for the response do not necessarily arise by combustion of the molecule but by a reaction involving alkali metal and the compound. This has been supported by thermodynamic parameters and molecular descriptors. The mechanism of the reaction that appears to be bimolecular has been explained by steric effects. The study successfully explains the observed change in the response of TID with minor changes in structures of the molecules.

Chromatography, Gas↗
PubMedDate not supplied

Alkoxide route for preparing hydroxyapatite and its coatings.

The preparation of hydroxyapatite using n-butanol or ethanol solutions of P2O5 and Ca glycoxide as precursors of P and Ca was investigated by nuclear magnetic resonance (NMR), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Stable mixed solutions of the precursors could be obtained in the presence of acetic acid (HOAC). For the mixed solution of Ca glycoxide with the ethanol solution of P2O5, a lower HOAC/Ca ratio was needed since the ethanol solution of P2O5 contained a lower concentration of H3PO4, a species that easily forms precipitates in the presence of the Ca containing species. An amorphous powder was obtained by heating the stable solution of Ca glycoxide and PO(OH)x(OEt)3-x with an HOAC/Ca ratio of 4 in a hot plate at approximately 150 degrees C. Hydroxyapatite (HAP) was directly formed after calcining the amorphous powder at 500 degrees C. The stable mixed solutions of Ca glycoxide and the alcoholic solutions of P2O5 were used to prepare HAP coatings on alumina substrates using a dip-coating method. The resulting ceramic coatings have a rough surface and an adhesion strength of about 10 MPa. The morphology of the coatings is dependent on the preparation chemistry.

Adhesiveness↗
PubMed2002

(13)C, (31)P and (15)N NMR studies of the ligand exchange reactions of auranofin and chloro(triethylphosphine)gold(I) with thiourea.

The interaction of thiourea (Tu) with auranofin (Et(3)PAuSATg) and its analogue, Et(3)PAuCl has been studied using (13)C, (31)P and (15)N NMR spectroscopy. It is observed that Tu is able to replace both the ligands, Et(3)P and SATg(-) simultaneously from gold(I) in auranofin, forming [Et(3)P-Au-Tu](+) and Tu-Au-SATg complexes. However, no separate resonances for these species were observed either due to their rapid exchange with auranofin and thus giving only the average resonances or because the chemical shifts of either two species are same so that they cannot be resolved. The displaced SATg(-) is oxidized to its disulfide, (SATg)(2). However, some of the displaced Et(3)P is oxidized to Et(3)PO while the remaining reacts with Tu to form Et(3)P-Tu species, characterized by delta 31P of 1.0 ppm, assigned after an independent reaction between Et(3)P and Tu. In an experiment using a 0.05 M solution of auranofin, the Et(3)PO resonance appeared in auranofin spectrum after 4 days of addition of 1.0 equivalent of Tu, showing that the reaction is slow. A resonance for free Et(3)P is also detected in 31P NMR on the addition of CN(-). It is also observed that Tu reacts with Et(3)PAuCl to form [Et(3)P-Au-Tu](+) via displacement of Cl(-), consistent with an upfield shift of 6.2 ppm in >C [double bond] S resonance of Tu in (13)C NMR. In (15)N NMR, a smaller downfield, instead of an upfield shift, in NH(2) resonance of Tu on its addition to auranofin and Et(3)PAuCl indicates that it is not binding to gold(I) through nitrogen.

Antirheumatic Agents↗
PubMed2002

Photoinduced cleavage by a rhodium complex at G.U mismatches and exposed guanines in large and small RNAs.

Photoinduced cleavage reactions by the rhodium complex tris(4,7-diphenyl-1,10-phenanthroline)rhodium(III) [Rh(DIP)(3)(3+)] with three RNA hairpins, r(GGGGU UCGCUC CACCA) (16 nucleotide, tetraloop(Ala2)), r(GGGGCUAUAGCUCUAGCUC CACCA) (24 nucleotide, microhelix(Ala)), and r(GGCGGUUAGAUAUCGCC) (17 nucleotide, 790 loop), and full-length (1542 nucleotide) 16S rRNA from Escherichia coli were investigated. The cleavage reactions were monitored by gel electrophoresis and the sites of cleavage by Rh(DIP)(3)(3+) were determined by comparisons with chemical or enzymatic sequencing reactions. In general, RNA backbone scission by the metal complex was induced at G.U mismatches and at exposed G residues. The cleavage activity was observed on the three small RNA hairpins as well as on the isolated 1542-nucleotide ribosomal RNA.

Base Composition↗
PubMed2001

A fluorescence-based assay for transcription using a novel fluorescent GTP analogue.

A new fluorescent analogue of GTP (Cm-GTP) was synthesized, which contained a coumarin fluorophore attached to the gamma phosphorus. This compound was tested in transcription assays using T7 RNA polymerase as a model system. The fluorescent nucleotide was incorporated specifically at the 5' end of nascent RNA synthesized in two different modes of transcription initiation. In the first mode, with only Cm-GTP (+GTP), reiterative slippage synthesis occurred and poly rG ladders of up to 14 nucleotides were synthesized. In the second mode, with Cm-GTP (+GTP)+ATP+CTP, abortive transcripts of up to seven or eight nucleotides were synthesized. The fluorescence properties of the two types of RNA were studied in detail. There was greater reduction in fluorescence intensity in G-ladders than in abortive transcripts. Steady-state anisotropy and anisotropy decay indicated that the fluorophore motion was constrained in G-ladder RNAs as compared to abortive RNAs. Quenching experiments by using extraneous quenchers showed that the excited state of fluorophore at the 5' end of G-ladder RNA was less efficiently quenched as compared to the free fluorophore. These studies suggested that the fluorescent GTP analogue sensed the structural features that distinguished G-ladder RNAs from abortive RNAs. The results suggested that G-ladder RNAs adapt unusual conformations such as G-quartets. Thus, the new fluorescent probe can be useful for structural studies on RNA.

Fluorescence↗
PubMed2001

Spill behaviour using REACTPOOL. Part III. Results for accidental releases of phosphorus trichloride (PCl(3)) and oxychloride (POCl(3)) and general discussion.

Phosphorus trichloride and oxychloride are aggressive materials, widely used in the process industries. On escape to the atmosphere they create toxic clouds that may cause serious damage to people and to the environment. When spilled onto the ground they create liquid pools that can boil, evaporate or even solidify. The main feature of the pool behaviour is the exothermic reaction of these chemicals with water, which is complicated and depends heavily on the amount of water available for reaction, and as result of which the pool has changing composition and properties. The purpose of this paper is to describe the dangers involved in cases of accidental releases of phosphorus trichloride and oxychloride, to report their properties, referring to toxicity data and major accidents. The spill behaviour of phosphorus trichloride and oxychloride has been incorporated into REACTPOOL [R.F. Kapias, C. Griffiths, J. Haz. Mater.]. Model results indicate that the pool behaviour is strongly affected by the amount of water available for reaction. Surface roughness and wind speed, also have a strong effect on the results. Although there are no experimental data for model validation, it is shown that REACTPOOL gives useful insights into the behaviour of such spills. The paper concludes with a discussion comparing the behaviour for several water reactive chemicals to which REACTPOOL has been applied.

Accidents, Occupational↗
PubMed1997

The determination of magnesium in human blood plasma by 31P magnetic resonance spectroscopy using a macrocyclic reporter ligand.

The ligand 1,4,7-triazacyclononane-1,4,7-tris(methylene methylphosphinic acid), NOTMP, was used to measure free MgII levels in blood plasma by 31P MRS. Separate resonances were observed for the free ligand and the MgII complex and the ratio of their resonance areas was used to evaluate the free, ionized MgII concentration, [Mg]free. The CaII and the ZnII complexes gave rise to separate resonances in the 31P spectrum in an aqueous sample. In human blood plasma samples, however, these resonances were never observed thus excluding the interference of these metal ions. Heparin, up to 150 units/ml, had no influence on the Mg-NOTMP equilibrium. The 31P MRS methodology was applied to twenty human blood plasma samples. Total MgII ([Mg]total), as measured by atomic absorption spectroscopy, averaged 0.85 +/- 0.12 mM while free ionized MgII ([Mg]free) measured by 31P MRS was 0.66 +/- 0.09 mM. The 31P MRS method gave inherently larger values for free ionized MgII than that reported by ion-selective electrodes (ISE). This was traced to a redistribution of existing plasma MgII species after the addition of about 2 mM of NOTMP. Calculations using existing thermodynamic data show that the ionized MgII concentration (iMg) and the concentration of MgII weakly complexed to small anions (Mg(comp)) both drop after the addition of NOTMP, with Mg(comp) dropping to negligible levels. Thus, the 31P MRS method appears to be less sensitive to variations in the concentration of weakly binding anions (bicarbonate, carbonate, chloride, lactate, phosphate, etc.) than the ISE method. Our data indicates that the difference between Mg(total), as measured by atomic absorption spectroscopy, and Mg(free), as measured by 31P MRS, provides an direct estimate of the protein bound MgII fraction.

Anions↗