bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of Environmental Properties for Chlorophenols with Posetic Quantitative Super-Structure/Property Relationships (QSSPR)
Authors: Ivanciuc Teodora , Ivanciuc Ovidiu , Klein Douglas J.
Published: October 2008

Due to their widespread use in bactericides, insecticides, herbicides, andfungicides, chlorophenols represent an important source of soil contaminants. Theenvironmental fate of these chemicals depends on their physico-chemical properties. In theabsence of experimental values for these physico-chemical properties, one can use predictedvalues computed with quantitative structure-property relationships (QSPR). As analternative to correlations to molecular structure we have studied the super-structure of areaction network, thereby developing three new QSSPR models (poset-average, cluster-expansion, and splinoid poset) that can be applied to chemical compounds which can behierarchically ordered into a reaction network. In the present work we illustrate these posetQSSPR models for the correlation of the octanol/water partition coefficient (log Kow) and thesoil sorption coefficient (log KOC) of chlorophenols. Excellent results are obtained for allQSSPR poset models to yield: log Kow, r = 0.991, s = 0.107, with the cluster-expansionQSSPR; and log KOC, r = 0.938, s = 0.259, with the spline QSSPR. Thus, the poset QSSPRmodels predict environmentally important properties of chlorophenols.
A Velocity Extraction Method in Molecular Dynamic Simulation of Low Speed Nanoscale Flows
Authors: Zhang Wenfei
Published: October 2008

A new algorithm to extract the velocity caused by the external forces inmolecular dynamic simulation of nanoscale flow problems is proposed. The flowvelocity, an important component in these type of problems, is usually obtained from theaverage value in the time space because the accumulation of the thermal velocity willapproach zero when the time period is large, but this method is not always suitable,especially when the flow velocity is much smaller than the thermal velocity. Based on theidea of the linear accumulation of the flow velocity, in this study a new algorithm isderived to extract the flow velocity. This algorithm can be used to calculate nanoscaleflow problem no matter whether the value of the flow velocity is big or small. Using thisnew algorithm, the 2-D liquid flow of argon in nanochannels was simulated. Thenumerical result demonstrates the effectiveness of the new algorithm.
Full Analytic Progress Curves of Enzymic Reactions in Vitro
Authors: Putz Mihai  V. , Lacrama Ana-Maria , Ostafe Vasile
Published: October 2008

Assuming the in vitro conditions for the enzyme-catalyzed reactions, the basic Michaelis-Menten description is modified in a logistic (mathematical) manner such that the inherent limitations that appear in the previous method are removed. Beside its generality, the reliability of the present approach is proved through applications on the competitive multi- and bi- substrate enzyme catalyses.
Triazoloquinazolines as Human A3 Adenosine Receptor Antagonists: A QSAR Study
Authors: Kim Dooil , Hong Suk-In , Lee Dae-Sil
Published: October 2008

Multiple linear regression analysis was performed on the quantitative structure-activity relationships (QSAR) of the triazoloquinazoline adenosine antagonists for human A3receptors. The data set used for the QSAR analysis encompassed the activities of 33triazoloquinazoline derivatives and 72 physicochemical descriptors. A template moleculewas derived using the known molecular structure for one of the compounds when bound tothe human A2B receptor, in which the amide bond was in a cis-conformation. All the testcompounds were aligned to the template molecule. In order to identify a reasonable QSARequation to describe the data set, we developed a multiple linear regression program thatexamined every possible combination of descriptors. The QSAR equation derived from thisanalysis indicates that the spatial and electronic effects is greater than that of hydrophobiceffects in binding of the antagonists to the human A3 receptor. It also predicts that a largesterimol length parameter is advantageous to activity, whereas large sterimol widthparameters and fractional positive partial surface areas are nonadvatageous.
Application of Chromatographic and Electrophoretic Methods for the Analysis of Imidazolium and Pyridinium Cations as Used in Ionic Liquids
Authors: Stepnowski P.
Published: October 2008

Interest in ionic liquids for their potential in different chemical processes isconstantly increasing, as they are claimed to be environmentally benign – excellent, non-volatile solvents for a wide range of applications. The wide applicability of thesecompounds also demands reliable, relatively simple and reproducible analytical techniques.These methods must be applicable not only to different technical or natural matrices but alsoto the very low concentrations that are likely to be present in biological and environmentalsystems. In this review, therefore, methods for separating and analysing imidazolium- andpyridinium-type ionic liquids in aqueous matrices using high performance liquidchromatography (HPLC) and capillary electrophoresis (CE) are examined. The techniquesfor identifying ionic liquids are meant primarily to track the concentrations of ionic liquidsas residues not only in products and wastes but also in biological or environmental samples.The application of hyphenated techniques in this field is intended to selectively separate thequaternary entity from other cationic and non-ionic species present in the matrix, and toenable its fine-scale quantification. Nowadays, methods developed for cation analysis arebased mostly on reversed-phase high-performance liquid chromatography, ionchromatography, ion-pair chromatography and capillary electrophoresis, where variousbuffered mobile phases are used.
The Quantitative Structure-Mutagenicity Relationship of Polycylic Aromatic Hydrocarbon Metabolites
Authors: Kim Dooil , Hong Suk-In , Lee Dae-Sil
Published: October 2008

Quantitative structure-activity relationships (QSARs) for benz[a]anthracene (BA)mutagens using 73 descriptors were searched. The mutagenicity data was obtained fromAmes assays for Mycobacterium vanbaalenii, Mycobacterium gilvum and Mycobacteriumflavescens strains. These data were fitted using a mutagenicity-cytotoxicity competitionmodel which defines the mutagenic potencies of BA metabolites, and include oxides,phenols, quinones, and dihydrodiols. The QSAR equations were derived using the moleculardescriptor set (charged partial surface area, spatial, thermodynamic and electronicdescriptors) and semi-empirical energetic and charge descriptors. Genetic functionapproximation was used to reduce and fit independent variables, including linear- andquadratic-based functions. Multiple QSAR equations were generated and a separate QSARequation was chosen and evaluated for each strain using conventional r2, F-test, and cross-validated r2. Each strain exhibited its own characteristic descriptors.
Laser photolysis study of anthraquinone in binary mixtures ofionic liquid [bmim][PF6] and organic solvent
Authors: Zhu Guanglai , Xu Jingjing , Wu Guozhong , Zhu Hongping , Long Dewu , Chen Shimou , Yao Side
Published: October 2008

Photochemical properties of the ionic liquid (RTIL) 1-butyl-3-methylimidazoliumhexafluorophosphate [bmim][PF6] and its binary mixed solutions with organic solvent(DMF and MeCN) were investigated by laser photolysis at an excitation wavelength of 355nm, using anthraquinone (AQ) as a probe molecule. It was indicated that the triplet excitedstate of AQ (3AQ*) can abstract hydrogen from [bmim][PF6]. Moreover, along with thechange of the ratio of RTIL and organic solvent, the reaction rate constant changes regularly.Critical points were observed at volume fraction VRTIL = 0.2 for RTIL/MeCN and VRTIL =0.05 for RTIL/DMF. For both systems, before the critical point, the rate constant increasesrapidly with increasing VRTIL; however, it decreases obviously with VRTIL after the criticalpoint. We conclude that the concentration dependence is dominant at lower VRTIL, while theviscosity and phase transformation are dominant at higher VRTIL for the effect of ionic liquidon the decay of rate constant.
Electron Charge Density Distribution from X-ray Diffraction Study of the M-Nitrophenol Compound in the Monoclinic Form
Authors: Hamzaoui Fodil , Drissi Mokhtaria , Chouaih Abdelkader , Lagant Philippe , Vergoten Gérard
Published: October 2008

At room temperature, the m-Nitrophenol (m-NPH) appears in two polymorphicstructures: orthorhombic and monoclinic forms. In the present work, we shall focus on themonoclinic form of this compound which has a centrosymmetric structure with the spacegroup P21/n. The molecular dipole moment has been estimated experimentally. Highresolution single crystal diffraction experiment was performed at low temperature withMoKα radiation. The crystal structure was refined using the multipolar model of Hansen andCoppens (1978). The molecular electron charge density distribution is described accurately.The study reveals the nature of inter-molecular interactions including charge transfer andhydrogen bonds. In this crystal, hydrogen bonds of moderate strength occur between thehydroxyl group and the O atom in the nitro one.
Genome-Wide Scan of the Gene Expression Kinetics of Salmonella enterica Serovar Typhi during Hyperosmotic Stress
Authors: Huang Xinxiang , Xu Huaxi , Sun Xiaosong , Ohkusu Kiyofumi , Kawamura Yoshiaki , Ezaki Takayuki
Published: October 2008

Salmonella enterica serovar Typhi is a human enteroinvasive pathogen that canovercome the stress caused by the high osmolarity of the human small intestine and causesystemic infection. To investigate the global transcriptional regulations of S. entericaserovar Typhi exposed to a hyperosmotic environment, a genomic oligo-DNA microarraycontaining 4474 Salmonella genes was prepared. A wild strain of S. enterica serovar TyphiGIFU10007 was grown in LB medium containing 50 mM NaCl to simulate a low osmoticenvironment. The hyperosmotic stress was simulated by an osmotic up-shift, whichincreased the concentration of NaCl in the LB from 50 mM to 300 mM. Genome-wide geneexpressions of S. enterica serovar Typhi at 15 min, 30 min, 60 min, and 120 min after theosmotic up-shift were investigated by the microarray analysis. Gene expression profiles insomewhat later stage (60 ~120 min) of the stress were quite different from those in the earlystage (0 ~ 30 min) of the stress. At 120 min after the osmotic stress, the expression levels of889 genes were obviously changed. However, expression levels of only 382 genes weresignificantly changed at 15 min after the osmotic stress. The expression levels of most SPI-1genes associated with invasion of the pathogen were increased at 120 min after the osmoticup-shift, but were not obviously changed at 15 min or 30 min after the osmotic stress.Expressions of a central regulatory gene, phoP, and sigma factor genes rpoE, rpoD, andrpoS were also changed with different profiles during the osmotic stress. These resultsindicated that the invasive ability of the pathogen is significantly increased after 2 h of hyperosmotic stress, and regulator PhoP and sigma factors RpoE, RpoD appear to participate in the network regulatory mechanisms that benefit the pathogen to adapt hyperosmotic environmental conditions. The later increased invasive ability of S. enterica serovar Typhi after hyperosmotic stress may be one reason why the pathogen performs invading in the distal ileum of human and not in areas of the upper small intestine.
Rotational Spectra of Symmetric Top Molecules in Ground andDifferent Vibrational Excited States, and Phenomenon of Resonance – Applying in CF3CCH
Authors: Motamedi Masoud
Published: October 2008

This paper deals with review of exploration of resonance in symmetric topmolecules in different vibrational excited states, vt = n (n =1, 2, 3, 4). Calculations for CF3CCH shows that resonance take place at [Eq. 20] and [Eq. 21] for v10 = 2 and v10 = 3 respectively. In order to account for splitting about 3 MHz for the - 2 series in v10 = 4 is necessary to introduce the element {J, k, l |f24| J, k + 2,l − 4} in fitting program.
Organo-niobate Ionic Liquids: Synthesis, Characterization and Application as Acid Catalyst in Pechmann Reactions
Authors: Soares Valerio C. D. , Alves Melquizedeque B. , Souza Ernesto R. , Pinto Ivana O. , Rubim Joel C. , Andrade Carlos  Kleber Z. , Suarez Paulo A. Z.
Published: October 2008

The combinations of 1-butyl-3-methylimidazolium chloride with NbCl5 yieldedionic mixtures with different melting point temperatures and acidity depending on theniobium molar fraction. The mixtures were characterized by thermal (DSC) andspectroscopic (FT-IR and 1H NMR) analysis. The Pechmann reactions of different phenolswith ethylacetoacetate, producing coumarins, was used as model to evaluate the catalyticbehavior of these mixtures as acid Lewis catalyst. These reactions were carried out usingacidic mixtures of 60 mol%.
Functional Analysis of the Drosophila Dnop5 Using Targeted RNA Interference
Authors: Zhang Yan , Ding Jie , Wan Yongqi , Xie Wei , Yuan Liudi
Published: October 2008

Dnop5 is a member of the conserved nop5/sik1 gene family, which encodecomponents of small nucleolar ribonucleoprotein(snoRNP) complexes. To study thefunction of DNop5, we generated the polyclonal antibody and determined its expressionpattern. It is highly expressed in different periods of the Drosophila development. We usedheritable RNA interference (RNAi) in combination with the yeast GAL4/UAS binarysystem to knock down the DNop5 protein. It resulted in lethality and dramatic somaticanomalies in RNAi mutant fly, in which the DNop5 protein is reduced efficiently. Northernblotting showed that the processing of 18S rRNA was disrupted in DNop5 knock down fly,but 28S rRNA is normal. These results suggest that DNop5 is essential for the Drosophilagrowth and function in the execution of early pre-rRNA processing steps that lead toformation of 18S rRNA.
Molecular Cloning and Characterization of a Novel Human Glycine-N-acyltransferase Gene GLYATL1, Which Activates Transcriptional Activity of HSE Pathway
Authors: Zhang Haoxing , Lang Qingyu , Li Jie , Zhong Zhaomin , Xie Fang , Ye Guangming , Wan Bo , Yu Long
Published: October 2008

The glycine-N-acyltransferase (GLYAT) is well known to be involved in thedetoxification of endogenous and exogenous xenobiotic acyl-CoA's in mammals.Unfortunately, the knowledge about the gene encoding GLYAT is very limited. Here wereport a novel gene encoding a GLYAT member, designated as GLYATL1, which was1546 base pairs in length and contained an open reading frame (ORF) encoding apolypeptide of 302 amino acids. GLYATL1 was a split gene that was consisted of 7 exonsand 6 introns and mapped to chromosome 11q12.1. The expression of GLYATL1 could befound in liver, kidney, pancreas, testis, ovary and stomach among 18 human tissues by RT-PCR analysis. Subcellular localization of myc-tagged GLYATL1 fusion protein revealedthat GLYATL1 was distributed primarily in the cytoplasm of COS-7 cells. Furthermore,through the pathway profiling assay, the GLYATL1 protein was found to activate HSEsignaling pathway in a dose-dependent manner when overexpressed in HEK293T cells.
Preparation and Characterization of a Chloroperoxidase-like Catalytic Antibody
Authors: Wang Fengyang , Huang Xueying , Du Li , Li Weiguo , He Hongxuan , Qi Chao
Published: October 2008

The small molecule, meso-tetra(α,α,α,α-o-phenylacetamidophenyl)porphyrin(Mr1147.0) was used as complete antigen to elicit MAb through the immunization and cellfusion techniques.The MAb 1F2 obtained was demonstrated to be very pure byMALDI/TOFMS.The subtype of MAb 1F2 is IgG2a, which has a relative molecular weightof 156,678.8 Da.No significant change in the intensity of absorption peaks in UV and CDspectra was observed over a pH range between 6 and 12.The high stability of the abzymeand the tight binding between Fe porphyrin and antibody were also demonstrated.Vmax, Km,κcat, κcat/Km for abzyme are 5.18 × 10-8 Ms-1, 1.50 × 10-8M , 0.518 s-1, 3.45 × 107 M-1s-1, respectively.The data obtained indicate that catalytic antibody has highcatalytic activity.The chloroperoxidase activity of MAb 1F2-Fe porphyrin complex is stablefrom 10 °C to 60 °C.
Polarization of T Lymphocytes Is Regulated by Mesenchymal Stem Cells in NZBWF1 and BALB/c Mice
Authors: Sun Lingyun , Liang Jun , Li Hui , Hou Yayi
Published: October 2008

Mesenchymal stem cells (MSCs) have been shown to suppress proliferation andactivation of T lymphocytes in vivo and in vitro although the molecular mechanism of theimmunosuppressive effect is not completely understood. To investigate theimmunoregulatory effects of mice bone marrow mesenchymal stem cells on T lymphocyte,MSCs from NZBWF1 and BALB/c mice were isolated and expanded from bone marrow,and identified with cell morphology and the surface phenotypes. CD3+ T lymphocytesisolated by nylon wool columns were co-cultured with PMA with or without the two strainsof MSCs. Then T cell apoptosis and intercellular cytokines of T cell were assessed by flowcytometry. Quantification of transcription factors T-box (T-bet) and GATA-binding protein3 (GATA-3) expressed in T cells was detected by RT-PCR and western blot. Our resultsshowed that there was a decrease of CD3+ T cell apoptosis when NW MSCs or Bc MSCswere added, and an increase of Th2 subset by NW MSCs and Th1 subset by Bc MSCs wereobserved by co-culturing MSCs with T lymphocytes. It is suggested that, by favoring Th1-cell development and inhibitory Th2-cell development, normal MSCs might interfere withthe SLE development, and that marrow-derived NW MSCs had defectiveimmunoregulatory function when compared with MSCs from healthy mouse strains.
High-level Expression of Cecropin X in Escherichia coli
Authors: Shen Yi , Lao Xue Gang , Chen Yuan , Zhang Hong Zu , Xu Xian Xiu
Published: October 2008

Cecropin X is a short cationic peptide with a broad antibacterial and antitumorspectrum. Here, we report the production of a tumor necrosis factor (TNFα)-cecropin Xfusion protein under the control of a temperature-inducible PR promoter in the bacterialexpression vector pRC. During fermentation, we studied and optimized essentialparameters including the type of host cells, medium, timing of induction, post-inductiontime and dissolved oxygen level. Using the suitable conditions in the fermentation, up to20 % ~ 23 % of the total cellular proteins is produced as the fusion protein, mostly in theform of inclusion bodies. After washing, on average about 5.27 g dried inclusion bodiescould be collected from 1 L broth and the purity of inclusion bodies reached 80 %.Cecropin X obtained by cleaving the fusion protein with cyanogen bromide showedremarkable tumorcidal activity against mouse Lewis lung carcinoma 3LL in vivo.
Variation of the Nuclear, Subnuclear and Chromosomal Flavanol Deposition in Hemlock and Rye
Authors: Feucht Walter , Dithmar Heike , Polster Jürgen
Published: October 2008

Nuclei of hemlock (Tsuga canadensis and Tsuga canadensis var. nana) wereinvestigated for the presence of flavanols. Histochemical staining with p-dimethylaminocinnamaldehyde proved to be a highly valuable method yielding a brightblue flavanol coloration for nuclei. There was a significant variation in flavanol deposition(1) among nuclei, (2) at the subnuclear level and also (3) along the chromosomes duringmitosis. The presence of flavanols in nucleoli could not be established probably becausethey were too small, measuring less than 1 μm in diameter. In contrast to Tsuga, the cellsand nuclei of rootlets from rye (Secale cereale) were totally devoid of natural flavanols.However, externally added flavanols, catechin and epicatechin, were bound to the ryenuclei, while the rather large nucleoli failed to associate with the flavanols. The strong sinkactivity of nucleoplasm and chromosomes for flavanols in Tsuga and Secale indicates aprocess which is apparently widespread even in distantly related plant species. Variationsin chromatin-associated flavanols could to some extent be induced byacetylation/deacetylation of histones, as confirmed in the present study by means of UV-VIS spectroscopic titrations of histone sulphate and chemically acetylated histone sulphate.
Inclusion Compounds of Dehydrocholic Acid with Solvents
Authors: Fogagnolo Marco , Fantin Giancarlo , Bortolini Olga
Published: October 2008

The host-guest inclusion of various organic solvents within dehydrocholic acid has been studied and the selectivity of enclathration determined by competition experiments.
Modification of Low Molecular Weight Polysaccharides from Tremella Fuciformis and Their Antioxidant Activity in Vitro
Authors: Wu Qiong , Zheng Cheng , Ning Zheng-Xiang , Yang Bao
Published: October 2008

In this study, sulfated low molecular-weight Tremella fuciformis polysaccharides(SLTP) with different sulfate contents were synthesized and their antioxidant activities,including superoxide anion radical, 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical andhydroxyl radical scavenging activities were investigated. The results indicated that,compared to natural Tremella fuciformis polysaccharide (TP) and low molecular weightTremella fuciformis polysaccharide (LTP), sulfated LTP (SLTP) exhibited strongerscavenging activity towards superoxide anion, DPPH and hydroxyl radicals. In all the casesthe effect was found to be dose dependent. The scavenging activity of SLTP was found tobe in parallel with the degree of sulfation of SLTP.
Solubilization of Single-walled Carbon Nanotubes with Single- stranded DNA Generated from Asymmetric PCR
Authors: Liang Zhiqiang , Lao Ruojun , Wang Jing , Liu Yongbiao , Wang Lihua , Huang Qing , Song Shiping , Li Genxi , Fan Chunhai
Published: October 2008

Carbon nanotubes (CNTs) can be effectively dispersed and functionalized bywrapping with long single-stranded DNA (ssDNA) synthesized by asymmetric PCR. ThessDNA-CNTs attached on surface of glass carbon electrode made it possible forelectrochemical analysis and sensing, which was demonstrated by reduction of H2O2 onhemoglobin/ssDNA-CNTs modified electrodes. This research showed the potentialapplication of DNA-functionalised CNTs in construction of future electrochemicalbiosensors.
3D-QSAR Study of Potent Inhibitors of Phosphodiesterase-4 Using a CoMFA Approach
Authors: Yang Zhaoqi , Sun Pinghua
Published: October 2008

Phosphodiesterase-4 (PDE4) plays an important role in treatment of asthma andchronic obstructive pulmonary disease. Thirty-one analogs displaying variable inhibition ofPDE4 were selected to develop models for establishing three-dimensional quantitativestructure-activity relationships (3D-QSAR). Comparative molecular field analysis(CoMFA) was conducted on the group of analogs to determine the structural requirementsfor potency in inhibiting PDE4. The resulting model exhibited good q2 and r2 values up to0.741 and 0.954 for CoMFA. The contributions from the steric and electrostatic fields were0.915 and 0.085 respectively. The 3D-QSAR model should be very useful for design ofnovel PDE 4 inhibitors.
Synthesis and Ab Initio/DFT Studies on 2-(4-methoxyphenyl)benzo[d]thiazole
Authors: Arslan Hakan , Algül Öztekin
Published: October 2008

2-aminothiophenol and 4-methoxybenzaldehyde were cyclized under microwaveirridation and solvent free conditions to synthesize 2-(4-methoxyphenyl)benzo[d]thiazole.The molecular structure and vibrational frequencies of the title compound in the groundstate have been investigated with ab initio (HF) and density functional theory methods(BLYP, B3LYP, B3PW91 and mPW1PW91) implementing the standard 6-311G(d,p) basisset. Comparison of the observed fundamental vibrational frequencies of title compound andcalculated results by HF and DFT methods indicate that B3LYP is superior to the scaledHF approach for molecular problems.
Measurement of Antioxidant Activity of Wine Catechins, Procyanidins, Anthocyanins and Pyranoanthocyanins
Authors: Muselík Jan , García-Alonso María , Martín-López María P. , Žemlička Milan , Rivas-Gonzalo Julián C.
Published: October 2008

Nowadays, there is considerable interest in finding out about antioxidants thatare consumed in the habitual diet. It is known that polyphenols are involved in reducing therisk of diseases associated with oxidative stress. The in vitro antioxidant activity of theprincipal wine polyphenolic compounds (catechins, procyanidins, anthocyanins andpyranoanthocyanins) was studied in this work. Four distinct methods were used to assessthe antioxidant capacity of the tested compounds: inhibition of peroxynitrite mediatedtyrosine nitration, TEAC (Trolox equivalent antioxidant capacity assay), FRAP (Ferricreducing/antioxidant power assay) and TBARS (thiobarbituric acid reactive substances)methods. In general, it could be concluded that procyanidins were, among the in vitrotested groups, the ones which showed more antioxidant capacity using the four differentmethods, followed by anthocyanins and pyranoanthocyanins. On the basis of the simpleregression testing, there was a statistically significant relationship between these differentmethods used in aqueous phase (r > 0.92). However, no correlation was found between theresults obtained in lipid media with the TBARS method and those obtained in the aqueousmedia (peroxynitrite scavenging activity, TEAC and FRAP methods).
Isotopic Effect on the Kinetics of the Belousov-Zhabotinsky Reaction
Authors: Rossi Federico , Rustici Mauro , Rossi Claudio , Tiezzi Enzo
Published: October 2008

In this work we present results about the deuterium isotope effect on the globalkinetics of a Belousov-Zhabotinsky reaction in batch conditions. A nonlinear dependenceof the Induction Period upon the percentage of deuterated reactants was found. The isotopiceffect on the bromination reaction of malonic acid was evaluated.
Antioxidant Potential, Lipid Peroxidation Inhibition and Antimicrobial Activities of Satureja montana L. subsp. kitaibelii Extracts
Authors: Ćetković Gordana S. , Čanadanović-Brunet Jasna M. , Djilas Sonja M. , Tumbas Vesna T. , Markov Siniša L. , Cvetković Dragoljub D.
Published: October 2008

The antioxidant activity of different Satureja montana L. subsp. kitaibelii extracts was tested by measuring their ability to scavenge reactive hydroxyl radical during the Fenton reaction, using ESR spectroscopy. Also, the influence of these extracts on lipid peroxyl radicals obtained during lipid peroxidation of: (I) sunflower oil (37°C, 3h) inducedby 4,4'-azobis(4-cyanovaleric acid) (ACVA) and (II) liposomes induced by 2,2'-azobis(2-amidino-propane)dihydrochloride (AAPH) was studied. n-Butanol extract had the bestantioxidant activity (100% at 0.5 mg/mL in Fenton reaction system; 89.21% at 5 mg/mL in system I; 83.38% at 5 mg/mL in system II). The antioxidant activities of the extracts significantly correlated with total phenolic content. The antimicrobial activity of Satureja montana L. subsp. kitaibelii extracts was investigated. Petroleum ether, chloroform and ethyl acetate extracts expressed a wide range of inhibiting activity against both gram-positive and gram-negative bacteria.
Electron-Capture Cross Sections of Ground-State O2+ Recoil Ions in Slow Collisions with H2 and O2
Authors: Hasan Asad T. , Gray Tom J.
Published: October 2008

We report the measured total charge-transfer (electron-capture) cross sectionsfor the ground state O2+ (X2πg) ions with H2 and O2 molecular gases in the collisionenergy range between 0.50 and 2 keV. The time-of-flight technique has been used tomeasure the fast neutral products from O2+ charge transfer reactions. The analyzedprocess has cross sections that continue to increase slowly, as a function of incidentenergy. Measured cross sections for O2+ H2, O2 systems are compared with previouslyavailable experimental and theoretical results in the literature.
Diastereoselective Synthesis of Cyclopentanediols by InCl3/Al Mediated Intramolecular Pinacol Coupling Reaction in Aqueous Media
Authors: Chen Yunhua , Wan Jieping , Wang Chunyan , Sun Cuirong
Published: October 2008

A “green” and practical intramolecular pinacol coupling reaction promoted by InCl3/Al catalysts in aqueous media has been developed. Under mild conditions, a novel class of polysubstituted cyclopentane-1,2-diols have been obtained with excellent diastereoselectivity.
Optimization of Single-Sensor Two-State Hot-Wire Anemometer Transmission Bandwidth
Authors: Ligęza Paweł
Published: October 2008

Hot-wire anemometric measurements of non-isothermal flows require the use of thermal compensation or correction circuitry. One possible solution is a two-state hot-wire anemometer that uses the cyclically changing heating level of a single sensor. The area in which flow velocity and fluid temperature can be measured is limited by the dimensions of the sensor’s active element. The system is designed to measure flows characterized by high velocity and temperature gradients, although its transmission bandwidth is very limited. In this study, we propose a method to optimize the two-state hot-wire anemometer transmission bandwidth. The method is based on the use of a specialized constanttemperature system together with variable dynamic parameters. It is also based on a suitable measurement cycle paradigm. Analysis of the method was undertaken using model testing. Our results reveal a possible significant broadening of the two-state hot-wire anemometer's transmission bandwidth.
Drilling in 1300 Feet of Water - Santa Barbara Channel, California
Authors: Harris L.M. , Llfrey W.T.
Published: October 2008

Available technology and equipment have proven adequate for carrying out successful floating drilling operations in water depths to 1300 feet on Federal Leases in the Santa Barbara Channel. California. System elements directly affected by water depth have performed satisfactorily with only a few minor design modifications.

INTRODUCTION

During the l2-month period following the Federal Lease Sale in the Santa Barbara Channel of February 6, 1968. Humble has drilled ten wells with floating rigs three of which have been in water depths in the range of 900 to 1300 feet. The adequacy of advance planning has been demonstrated by the few problems that have occurred that are directly related to water depth. The first of the deepwater wells was spudded in 994 feet of water on August 5. 1968. as shown in Figure 1. This rig (WODECO IV) has now completed the drilling of a well in 1300 feet of water. The first deepwater well for the second rig (Blue Water II) was spudded in 941 feet of water on December 3. 1968. Both rigs are shown in Figure 2.

It is the purpose of this paper to present information as to:The location and environment of the deepwater drilling program.The criteria governing selection of the rigs used.Details of the systems used including design considerations and methods.Operating procedures.Operating results.

THE SANTA BARBARA CHANNEL WINDS, WAVES. AND CURRENTS

The Santa Barbara Channel is an area of the Pacific Ocean that is bounded on the north by the portion of the California coastline extending from Point Conception on the west to Ventura on the east and is bounded on the south by the Channel Islands of San Miguel, Santa Cruz and Anacapa. Industry's previous experience with floating drilling in the Channel had shown the environment to be relatively mild. Oceanographic and meterological references provided the best available data on winds waves and currents for guidance in the selection and design of equipment and in the formulation of operating practices. Sites in the area covered by specific reports are also shown on Figure 1. Historical data indicated that the probable yearly maximum conditions in the central Santa Barbara Channel would not exceed:Five-minute average winds of 65 knots from the west and northwest or from the east and southeast.Significant wave heights of 16 feet with a period of 13 seconds. Maximum waves associated with this sea state would probably be approximately 30 feet.Surface or near-surface currents of 2.4 knots parallel to the California coastline.

The data showed generally that these conditions would occur for only a very small percentage of the time in winter months in the main part of the Channel east of Point Conception. Near the west end of the Channel, a yearly maximum significant wave height of IS feet might occur with somewhat greater frequency.

CRITERIA FOR RIG SELECTION

On the basis of the water depths for the leases offered, the rig selection criteria emphasized deepwater operations and the economics of timing.
Acquisition of Critical Metocean Data on the Norwegian Deepwater Frontier
Authors: Saetre H.J.
Published: October 2008

Following the 1996 award of seven deepwater licenses, the offshore industry in Norway has instituted a joint meteorological and oceanographic (metocean) project within the Norwegian Deepwater Programme. An overall and very general data acquisition programme has been established, based on a strategy that has required the full commitment of license management in eight national and international oil companies on investments early in the exploration phase. Because the consequence of excessively conservative criteria and procedures may be quite different for a deepwater producing system, it is only through a full understanding of the physical environment and accurate engineering procedures that we can hope to carry out deepwater development in a safe and cost effective manner.

The data acquisition system has taken advantage of extensive use of moored acoustic Doppler current profilers, 3-dimensional numerical ocean model to simulate currents and current statistics, and remote sensing data from earth orbiting satellites to study velocity anomalies and mesoscale ocean features such as fronts and eddies. Three main issues - the integrated data acquisition system, data correlation analysis and the temporal and spatial variability of the currents - are addressed in the present paper. Although the 4–5 year project is not completed yet, it may be concluded that a high proportion of the objectives has been obtained, and that future field developments in the Norwegian deepwater areas can base their design on a sound and viable metocean database.

Introduction

The Norwegian offshore petroleum exploration industry was, by the 15th round licenses awarded in 1996, taking a significant step into a new regime; from the Norwegian Continental Shelf (NCS) with water depths up to 350 metres, into the much deeper areas of the continental slope and even down towards the deep abyssal plains. In addition, the climatic conditions in the Moere and Voering Basins are severe, with frequent storms and strong currents to be contended with.

The deepwater licenses were limited to five areas:Blocks 6704/12, 6705/10 and 6604/2/3 (Gjallar Ridge) with water depths ranging from 1175 to 1450 metres.Blocks 6706/11/12 and 6707/10/11 (Vema Dome and NykHigh) with water depths ranging from 1050 to 1525 metres.Blocks 6504/9/12, 6505/7/10, 6404/3 and 6405/1(Helland-Hansen) with water depths ranging from 675 to 950 metres.Blocks 6302/4/5/7/8 (Moere West) with water depthsranging from 1075 to 1600 metres.Blocks 6305/1/2/4/5, 6304/9 and 6305/7 (Ormen Lange)with water depths ranging from 450 to 1225 metres.

This paper addresses the metocean data collection and analysis programme established to provide the best possible database for the exploration phase and the future development of the Norwegian deepwater area.
Maximum of Permissible Horizontal Motions a Floating Drilling Vessel
Authors: Hansford John E. , Lubinski Arthur E.
Published: October 2008

Horizontal vessel motions [i.e., drift, sway or surge] result in bending of the drill string members in the Vicinity of the rotary drive bushing at the-vessel and at the blowout preventer close to the seafloor. Allowable horizontal vessel motions are calculated as a function of hookload, using both cumulative fatigue damage and drill pipe strength as criteria for drilling and for pulling stuck pipe. The presently used rule of limiting horizontal vessel motion to 5 percent of water depth is shown-to be too restrictive in some cases and too lenient in others.

INTRODUCTION

When drilling from a floating vessel} the rotating drill string is subjected to fatigue damage caused by reversing stresses which arise from heave, roll, pitch and horizontal motions of the vessel. In Ref. 1, the authors have examined the effect of drilling vessel roll and pitch on the cumulative fatigue damage of the kelly and the first joint of drill pipe below the kelly. As a continuation of that investigation, the present study covers the effect of horizontal motions of the vessel on the drill string.

Horizontal departure from over the borehole may be oscillatory [i.e., sway or surge], static [i.e., drift] or most often, some combination of the two. An accepted limit of horizontal vessel motion of percent of the water depth has been suggested and frequently followed.2 In reality, the allowable motion is strongly influenced by the hookload. Motions greater than 5 percent of water depth are often permissible, and under some conditions, motions should be limited to less than 5 percent of water depth. The purpose of this paper is to suggest maximum permissible motions imposed by drill pipe fatigue damage and pipe strength, as a function of hookload.

IDEALIZED SYSTEM

Fig. 1 shows an idealized system, highly exaggerated for explicitness. Although pipe bends are shown quite acute, bending stresses were properly defined mathematically. The pipe bending at the rotary drive bushing [labeled RDB in Fig. 1] is relieved in most cases by a gimbaled bushing and largely taken by the kelly, a more durable member. Therefore, the point of most severe damage is in the area of the blowout preventer rams [labeled BOP].

Generally, the drill pipe is run inside a larger pipe called a riser, which provides a return for the drilling mud from the sea floor to the vessel. For the sake of simplicity) the interaction of the drill pipe with the riser was not considered in this investigation. It is believed that the effect of this interaction on drill pipe bending is small.

The dimension D in Fig. 1 is the distance from the rotary drive bushing to the blowout preventer. This distance throughout this paper is called water depth which may or may not correspond closely enough to the reality to be used interchangeably. When in doubt, the true distance D should be used and substituted for water depth when using the curves in this paper.

The dimension H in Fig. 1 is the horizontal departure of the vessel from over the borehole.
Methanol Floating Production Storage and Offloading (MFPSO)
Authors: Remeljej Cameron
Published: October 2008

BHP Petroleum and Diamond Research & Development Australia Pty Ltd (a wholly owned subsidiary of Mitsubishi Corporation) have developed a detailed design basis for Methanol Floating Production Storage and Offloading (MFPSO) facilities using a new compact natural gas reforming process and existing low pressure methanol synthesis technology developed by ICI.

This paper will describe the three main development steps - choice of process, proving of the new compact reforming technology and detailed MFPSO technical feasibility studies, completed to fully assess the suitability of the concept for offshore application. The preferred design is based on a single train reforming system and is applicable to a range of plant capacities up to approximately 4500 t/d. This is nearly twice the capacity of many of the large single train land based methanol plants which employ conventional reforming technology. Detailed capital and operating cost estimates have also been prepared. As a result it is now possible to fully evaluate whether specific hydrocarbon resources are suitable candidates for monetisation using an MFPSO.

It has been concluded that the production of methanol from natural gas on an FPSO is safe and practicable. The technology developed offers a real alternative to gas reinjection on developments where flaring is prohibited, or as a method of commercialising stranded gas resources.

Introduction

The perceived need to be able to economically convert quantities of gas into marketable liquids offshore has been increasing over the past few years. This has generally resulted from anticipated future flaring restrictions on the associated gas production from new oil developments (environmental pressures to reduce greenhouse gas emissions and conserve resources are increasing). There is also an increasing desire to monetise significant volumes of stranded gas and add value to marginal oil discoveries.

Apart from LNG production, the other option for gas conversion in remote or deep water offshore locations, where pipeline distribution or reinjection of the gas is impracticable, is the conversion of the low value gas to synthesis gas and subsequently to a derivative liquid of choice. Methanol and Fischer Tropsch products are the main synthesis gas derived liquids that currently have well proven synthesis processes and established markets, although at vastly different market sizes.

A new driver for developing offshore gas to liquids technology is an anticipated future need for more environmentally friendly fuels.
Offshore Gas to Liquids
Authors: Rodvelt Sigmund , Schanke Dag , Fosen Per Eirik
Published: October 2008

This paper gives a technical description of two concepts for offshore conversion of associated gas to synthetic hydrocarbons (syncrude) by the Fischer-Tropsch process.

The solution represents an alternative to flaring or injecting associated gas and thus provides a means to exploit new oil fields in an environmentally sound way.

Two concepts are presented, a 4300 b/d syncrude plant on a Multipurpose Shuttle Tanker (MST) and 14500 b/d syncrude production on a dedicated ship. Both have been designed for the harsh weather conditions in the Norwegian Sea.

Studies have shown that the concepts are technically feasible and indicate that the safety requirements for offshore installations can be met.

Introduction

Flaring of gas has become an environmental issue with high degree of focus among approving authorities as well as the oil companies. Handling of associated gas for oil developments has therefore become a more critical issue than before. This has led the oil and gas industry to seek solutions that can handle the associated gas in an acceptable manner both economically and environmentally.

Excluding cold venting and flaring as alternatives, two main technical concepts exist for handling associated gas; injectionof gas into a reservoir or conversion to a transportable product. The attractiveness of the latter is heavily dependent on field location and type of reservoir. Gas can either be reinjected into the oil producing reservoir or into a separate reservoir nearby. In cases where gas reinjection has a positive effect on oil production, gas conversion is of limited interest during the injection period. For later recovery of the injected gas, gas conversion may represent an alternative. In the case where gas is merely disposed of into a non-producing reservoir or even affects oil production in an adverse manner, gas conversion may be competitive.

Conversion of gas to transportable products can generally bedivided in two groups. In the first group, gas is processed to "transportable gas" in the form of LNG, CNG or gas hydrate. The second approach is to convert gas chemically to another product, either methanol or synthetic hydrocarbons ("syncrude").

In particular LNG has the potential to handle relatively large amounts of natural gas and several concepts have been presented in recent years (ref. 1,2). CNG and gas hydrate are relatively new concepts generally aiming at smaller capacities (ref. 3,4). Although technically simpler and less costly than chemical conversion, all three gas-to-transportable gas concepts share the disadvantage of needing separate product logistics.
On the Design and Installation of an Innovative Deepwater Taut-Leg Mooring System
Authors: Ma Wei , Huang Ken , Lee Ming-Yao , Albuquerque Sergio , Palazzo Fabio Gondim
Published: October 2008

The aim of this paper is to identify important design parameters and consolidate installation experiences from the recently installed deepwater taut-leg mooring system for Petrobras' P-27 semi-submersible floating production system offshore Brazil. The P-27 mooring system consists of 12 anchoring lines with polyester ropes and vertically loaded plate anchors (the World's first practical installation of VLAs). This paper emphasizes the innovative aspects of using polyester ropes for a permanent mooring system.

Synthetic ropes have recently been employed in several offshore deepwater installations. Among various synthetic rope materials, polyester rope is the most popular due to its light weight, high strength, low elastic modulus, and relatively low manufacturing cost. On the other hand, synthetic rope is still in its early stages of practical offshore applications, and there are concerns regarding design methods, design criteria and installation techniques.

This paper addresses these concerns by comparing dynamic mooring simulation results of the polyester mooring system with those of typical steel wire/chain mooring systems based on the P-27 design parameters. Discussions on the handling, installation, inspection and maintenance of the polyester mooring system included in this paper are based on the actual execution of the P-27 project. It is found that conventional mooring analysis and installation techniques can be conveniently adapted to provide a consistent performance evaluation and deployment strategy of the polyester taut-leg mooring system.

Introduction

With the recent rapid growth in deepwater production projects offshore Brazil, American Bureau of Shipping (ABS) is actively involved in the classification of several conversions including semi-submersibles and tanker-based FPSOs (Floating Production, Storage and Offloading) for Petrobras. Most of these floating platforms will be moored in ever increasing water depths. In deep water, the conventional catenary mooring systems become less stiff and have a larger horizontal spread, with much higher mooring component costs and payload penalties. To cope with these challenges, Petrobras is leading the offshore industry in utilizing new mooring systems for stationkeeping of these platforms, which include polyester ropes and/or VLAs in conjunction with the taut leg mooring systems. It is predicted that the use of these new systems will grow in the near future for deepwater mooring applications [Ref.1 & 2]. ABS is responsible for the classification of the P-27 for Petrobras. This paper will demonstrate the innovative aspects of using polyester ropes and VLAs for this permanent taut-leg mooring system through parametric studies.