bluuebunny/crossref_metadata_2025 huggingface dataset:
A GMDH Approach to Modelling Gibbsite Solubility in Bayer Process Liquors
Authors: Bennett Frederick R. , Crew Peter , Muller Jennifer K.
Published: October 2008

The most widely employed industrial process for producing alumina (Bayer process) involves the dissolution of available aluminium hydroxide minerals present in raw bauxite into high temperature sodium hydroxide solutions. On cooling of the solution, or liquor in the industrial vernacular, Al is precipitated from solution in the form of gibbsite (Al(OH)3). In order to optimise the process, a detailed knowledge of factors influencing gibbsite solubility is required, a problem that is confounded by the presence of liquor impurities. In this paper, the use of the Group Method of Data Handling (GMDH) polynomial neural network for developing a gibbsite equilibrium solubility model for Bayer process liquors is discussed. The resulting predictive model appears to correctly incorporate the effects of liquor impurities and is found to offer a level of performance comparable to the most sophisticated phenomenological model presented to date.
Electronic Density Approaches to the Energetics of Noncovalent Interactions
Authors: Ma Yuguang , Politzer Peter
Published: October 2008

We present an overview of procedures that have been developed to compute several energetic quantities associated with noncovalent interactions. These formulations involve numerical integration over appropriate electronic densities. Our focus is upon the electrostatic interaction between two unperturbed molecules, the effect of the polarization of each charge distribution by the other, and the total energy of interaction. The expression for the latter is based upon the Hellmann-Feynman theorem. Applications to a number of systems are discussed; among them are dimers of uracil and interacting pairs of molecules in the crystal lattice of the energetic compound RDX.
Calculated Electronic Behavior and Spectrum of Mg+@C60 Using a Simple Jellium-shell Model
Authors: Even W. , Smith J. , Roth M. W. , Schuessler H.  A.
Published: October 2008

We present a method for calculating the energy levels and wave functions of any atom or ion with a single valence electron encapsulated in a Fullerene cage using a jelluim-shell model. The valence electron-core interaction is represented by a one-body pseudo-potential obtained through density functional theory with strikingly accurate parameters for Mg+ and which reduces to a purely Coulombic interaction in the case of H. We find that most energy states are affected little by encapsulation. However, when either the electron in the non-encapsulated species has a high probability of being near the jellium cage, or when the cage induces a maximum electron probability density within it, the energy levels shift considerably. Mg+ shows behavior similar to that of H, but since its wave functions are broader, the changes in its energy levels from encapsulation are slightly more pronounced. Agreement with other computational work as well as experiment is excellent and the method presented here is generalizable to any encapsulated species where a one-body electronic pseudo-potential for the free atom (or ion) is available. Results are also presented for off-center hydrogen, where a ground state energy minimum of -14.01 eV is found at a nuclear displacement of around 0.1 Å.
Application of the Extended Grunwald-Winstein Equation to Solvolyses of n-Propyl Chloroformate
Authors: Kyong Jin  Burm , Won Hoshik , Kevill Dennis   N.
Published: October 2008

Application of the extended Grunwald-Winstein equation to solvolyses of n-propyl chloroformate in a variety of pure and binary solvents indicates an addition-elimination pathway in the majority of the solvents but an ionization pathway in the solvents of highest ionizing power and lowest nucleophilicity. For methanolysis, a solvent deuterium isotope effect of 2.17 is compatible with the incorporation of general-base catalysis into the substitution process. Activation parameters are consistent with the duality of mechanism. Very modest positive salt effects are observed on adding chloride or bromide salts to the ethanolysis.
Inhibition of Heme Peroxidase During Phenol Derivatives Oxidation. Possible Molecular Cloaking of the Active Center
Authors: Ziemys Arturas , Kulys Juozas
Published: October 2008

Ab initio quantum chemical calculations have been applied to the study of the molecular structure of phenol derivatives and oligomers produced during peroxidasecatalyzed oxidation. The interaction of substrates and oligomers with Arthromyces ramosus peroxidase was analyzed by docking methods. The most possible interaction site of oligomers is an active center of the peroxidase. The complexation energy increases with increasing oligomer length. However, the complexed oligomers do not form a precise (for the reaction) hydrogen bonding network in the active center of the enzyme. It seems likely that strong but non productive docking of the oligomers determines peroxidase inhibition during the reaction.
Study of Polymorph Prediction For L-Ascorbic Acid
Authors: Arslantas Ali , Ermler Walter   C. , Yazici Rahmi , Kalyon Dilhan   M.
Published: October 2008

Possible polymorphs of L-ascorbic acid were investigated, considering eight space groups and assuming one molecule in the asymmetric unit. The grid-search method was compared with a Monte Carlo approach as performed in the Biosym / MSI polymorph Predictor. A number of possible crystal structures were found, including the experimental structure. Energy minimizations were performed with a united-atom force field. In all cases, the experimental structure had a low lattice energy. The number of hypothetical crystal structures was reduced considerably by removing space-group symmetry constraints, or by a primitive molecular dynamic shake-up. Nevertheless, sufficient structures of equal or lower energy compared with the experimental structure remained to suggest that other factors need to be considered for polymorph predictions of materials.
Study of Polymorph Prediction for L-Ascorbic Acid [Int. J. Mol. Sci. 2005, 6, 291-302]
Authors: Arslantas Ali , Ermler Walter  C. , Yazici Rahmi , Kalyon Dilhan  M.
Published: October 2008

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Reaction of 2,2-Diphenyl-1-picrylhydrazyl with HO•, O2•–, HO– ,and HOO– Radicals and Anions
Authors: Hristeac Elena  N. , Caproiu Miron  T. , Pencu Gabriela , Hillebrand Mihaela , Constantinescu Titus , Balaban Alexandru  T.
Published: October 2008

Using electronic absorption spectra and thin layer chromatography, the reactionof 2,2-diphenyl-1-picrylhydrazyl (DPPH) with O2•–, HO•, HO–, and HOO– anions and freeradicals revealed the formation of the para-nitro- and para-hydroxy-derivatives of 2,2-diphenyl-1-picrylhydrazine (DPPH-H) and of DPPH fragmentation products(diphenylamine, tetraphenylhydrazine). The reaction of DPPH with the O2•– anion-radical(from KO2 in benzene solution at room temperature in the presence of 18-crown-6 ether) ispseudo-first-order during the first 25 minutes.
Publisher's Note - Overlapping Pagination Error
Authors: Lin Shu-Kun
Published: October 2008

Publisher's Note added on 3 August 2006: There is an overlapping pagination error. The paper "Int. J. Mol. Sci. 2006, 7, 131-154" is republished as "Int. J. Mol. Sci. 2006, 7, 231-254. Pages 144-154 are thus taken as blank pages. We apologize for this error and for any inconvenience.
The Electronic Structure of the Nitrogen Atoms of Allyl (5- pyridin-2-yl-[1,3,4]-thiadiazol-2-yl)-amine
Authors: Strzemecka Leokadia
Published: October 2008

The resonance structures of allyl-(5-pyridin-2-yl-[1,3,4]-thiadiazol-2-yl)-aminehave been determined by means of its 1H- (100 MHz, 500 MHz) 13C- and 15N-NMRspectra and B3LYP/6-31G* computations. The tautomeric equilibrium of this compoundhas been observed in the 1H-NMR spectra (100 MHz).
Epigallocatechin-3-Gallate Ameliorates Alcohol-Induced Liver Injury in Rats
Authors: Yuan Guangjin , Gong Zuojiong , Zhou Xiaorong , Zhangq Pin , Sun Xiaomei , Li Xi
Published: October 2008

Endotoxemia is a common event in alcoholic liver disease. Elevated intestinalpermeability is the major factor involved in the mechanism of alcoholic endotoxemia andthe pathogenesis of alcoholic liver disease. This study examined the effect ofepigallocatechin-3-gallate (EGCG) on alcohol-induced gut leakiness, and explored therelated mechanisms involved in its protection against alcohol-induced liver injury in rats.Four groups of female Sprague-Dawley rats were studied. Alcohol and alcohol/EGCGgroups rats received fish oil along with alcohol daily via gastrogavage for 6 weeks, anddextrose and dextrose/EGCG groups rats were given fish oil along with isocaloric dextroseinstead of alcohol. The dextrose/EGCG and alcohol/EGCG groups received additionaltreatment of EGCG (100mg.kg-1 body weight) daily intragastrically by gavage. Intestinalpermeability was assessed by urinary excretion of lactulose and mannitol (L/M ratio). Liverinjury was evaluated histologically and by serum alanine aminotransferase (ALT). Plasmaendotoxin and serum tumor necrosis factor-α (TNF-α) levels were assayed; livermalondialdehyde (MDA) contents determined. CD14 and inflammatory factors, such asTNF-α, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) mRNAs inthe liver were analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). Ratsgiven fish oil plus alcohol had gut leakiness (L/M ratio was increased), which wasassociated with both endotoxemia and liver injury. The above responses were accompaniedby increased CD14, TNF-α, COX-2 and iNOS mRNA expressions in the liver. EGCGsupplementation partly blocked the gut leakiness, reduced endotoxemia and lipidperoxidation, and blunted the elevated expressions of CD14, TNF-α, COX-2 and iNOS, allof which were associated with improved liver injury. These results show that EGCG can block alcohol-induced gut leakiness, reduce endotoxemia, and inhibit inflammatory factors expressions in the liver, thereby ameliorates alcohol-induced liver injury.
"Int. J. Mol. Sci. 2006, 7, 131-154" is republished as "Int. J. Mol. Sci. 2006, 7, 231-254"
Authors: Lin Shu-Kun
Published: October 2008

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Expression of Myosin Light Chain Kinase in Kidney of Streptozotocin-Induced Diabetic Rats
Authors: Zhu Huaqing , Zhang Xiaolin , Zuo Li , Zhou Qing , Gui Shuyu , Wei Wei , Wang Yuan
Published: October 2008

Nephropathy is one of the most common complications of diabetes mellituswhich remains incompletely understood. We reported the expression of myosin light chainkinase (MLCK) in the kidney of diabetic rats and investigated the correlation betweenMLCK and diabetic nephropathy by observing the expression of MLCK. The diabetic modelrats were induced by an intraperitoneal injection of streptozotocin (STZ) and the insulin-treated rats were subcutaneously injected with protamine zine insulin 3u/d. The kidneyswere excised and immersed in 4% polyoxymethylene after 12 weeks later. The expression ofMLCK was analyzed by immunohistochemical staining and Western blot.Immunohistochemical analysis and Western blot assay indicated that the MLCK expressionwas higher in kidney of diabetic rats than that in control and it was decreased in kidney ofinsulin-treated rats. Our results suggested that the over expression of MLCK may be relatedwith the development of diabetic nephropathy.
Binding of Fidarestat Stereoisomers with Aldose Reductase
Authors: Kim Dooil , Hong Suk-In , Lee Dae-Sil
Published: October 2008

The stereospecificity in binding to aldose reductase (ALR2) of two fidarestat {6-fluoro-2',5'-dioxospiro[chroman-4,4'-imidazolidine]-2-carboxamide} stereoisomers [(2S,4S)and (2R,4S)] has been investigated by means of molecular dynamics simulations using freeenergy integration techniques. The difference in the free energy of binding was found to be2.0 ± 1.7 kJ/mol in favour of the (2S,4S)-form, in agreement with the experimentalinhibition data. The relative mobilities of the fidarestats complexed with ALR2 indicate alarger entropic penalty for hydrophobic binding of (2R,4S)-fidarestat compared to (2S,4S)-fidarestat, partially explaining its lower binding affinity. The two stereoisomers differmainly in the orientation of the carbamoyl moiety with respect to the active site and rotationof the bond joining the carbamoyl substituent to the ring. The detailed structural andenergetic insights obtained from out simulations allow for a better understanding of thefactors determining stereospecific inhibitor-ALR2 binding in the EPF charges model.
Design of Anti-HIV Ligands by Means of Minimal Topological Difference (MTD) Method
Authors: Duda-Seiman Corina , Duda-Seiman Daniel , Dragos Dan , Medeleanu Mihai , Careja Valentin , Putz Mihai  V. , Lacrama Ana-Maria , Chiriac Adrian , Nutiu Remus , Ciubotariu Dan
Published: October 2008

Molecular modeling and MTD methods are useful tools to assess both qualitative(SAR) and quantitative (QSAR) chemical structure-biological activity relationships. The 1-[(2-hydroxiethoxi)-methyl]-6-(phenylthio)thymine congeners (HEPT ligands) show in vitroanti-viral activity against the type-1 human immunodeficiency virus (HIV-1), which is theetiologic agent of AIDS. This work shows an extensive QSAR study performed upon a largeseries of 79 HEPT ligands using the MTD and HyperChem molecular modeling methods.The studied HEPT ligands are HIV reverse-transcriptase inhibitors. Their geometries wereoptimized and conformational analysis was carried out to build the hypermolecule, whichallowed applying the MTD method. The hypermolecule was used for space mapping of thereceptor’s interaction site. The obtained results show that there are three 3D molecular zonesimportant for the anti-HIV biological activity of the HEPT ligands under study.
Identification and molecular modeling of a family 5 endocellulase from Thermus caldophilus GK24, a cellulolytic strain of Thermus thermophilus
Authors: Kim Dooil , Park Bo  Hyun , Jung Bo-Won , Kim Mi-kyung , Hong Suk-In , Lee Dae-Sil
Published: October 2008

The genome of T. caldophilus GK24 was recently sequenced and annotated as 14contigs, equivalent to 2.3 mega basepairs (Mbp) of DNA. In the current study, we identifieda unique 13.7 kbp DNA sequence, which included the endocellulase gene of T. caldophilusGK24, which did not appear to be present in the complete genomic sequence of the closelyrelated species T. thermophilus HB27 and HB8. Congo-red staining revealed a uniquephenotype of cellulose degradation by strain GK24 that was distinct from other closelyrelated Thermus strains. The results showed that strain GK24 is an aerobic, thermophilic,cellulolytic eubacterium which belongs to the group T. thermophilus. In order to understandthe mechanism of production of cellobiose in T. caldophilus GK24, a three-dimensionalmodel of the endocellulase, TcCel5A, was generated based on known crystal structures.Using this model, we carried out a flexible cellotetraose docking study.
Supramolecular Coordination Polymers by Self-assembling of Bis-monodentate Ligands with HgI2
Authors: Li Xiaokang , Fan Xiaolin , Zeng Qingdao
Published: October 2008

Two supramolecular coordination polymers, [HgI2(L1)·0.5H2O]∞ (1) and[HgI2(L2)·0.4CH3OH]∞ (2), have been prepared by ligands L1 (L1 = bis[4-(4-pyridylmethyleneamino)phenyl] ether) and L2 (L2 = N,N′-bis(3-pyridylmethyl)-diphthalicdiimide) with HgI2, respectively. 1 formed an interestingly infinite cross-linked doublehelical structure, whereas 2 formed the one-dimensional zigzag chains, which are parallelwith each other.
Hsp90 Maintains the Stability and Function of the Tau Phosphorylating Kinase GSK3β
Authors: Dou Fei , Chang Xingya , Ma Da
Published: October 2008

Hyperphosphorylation of tau leading to aggregated tau and tangle formation is acommon pathological feature of tauopathies, including Alzheimer's disease. Abnormalphosphorylation of tau by kinases, in particular GSK3β, has been proposed as a pathogenicmechanism in these diseases. In this study we demonstrate that the heat shock protein 90(Hsp90) maintains the stability and function of the GSK3β. By using both rat primarycortical neurons and COS-7 cells, we show that Hsp90 inhibitors lead to a reduction of theprotein level of GSK3β, and that this effect is associated with both a decrease in tauphosphorylation at putative GSK3β sites and an induction in heat shock protein 70 (Hsp70)levels. We further show that Hsp90 associates with the GSK3β regulating its stability andfunction and preventing its degradation by the proteasome.
Microwave-Assisted Synthesis of Phenothiazine and Qinoline Derivatives
Authors: Găină Luiza , Cristea Castelia , Moldovan Claudia , Porumb Dan , Surducan Emanoil , Deleanu Calin , Mahamoud Abdalah , Barbe Jacques , Silberg Ioan A.
Published: October 2008

Application of a dynamic microwave power system in the chemical synthesis ofsome phenothiazine and quinoline derivatives is described. Heterocyclic ring formation,aromatic nucleophilic substitution and heterocyclic aldehydes/ketones condensationreactions were performed on solid support, or under solvent free reaction conditions. Themicrowave-assisted Duff formylation of phenothiazine was achieved. Comparison ofmicrowave-assisted synthesis with the conventional synthetic methods demonstratesadvantages related to shorter reaction times and in some cases better reaction yields.
Efficient Gene Transfection into Mammalian Cells Mediated by Cross-linked Polyethylenimine
Authors: Dong Wei , Li Shufeng , Jin Guanghui , Sun Qiming , Ma Dingyuan , Hua Zichun
Published: October 2008

25 kDa branched polyethylenimine (PEI) has successfully been used for in vitroand in vivo gene delivery approaches, but it is cytotoxic. Smaller PEIs are usually non-cytotoxic but less efficient. In order to enhance the gene delivery efficiency and minimizecytotoxicity of PEI, we explored to synthesize cross-linked PEIs with degradable bonds byreacting amines of small branched 2000 Da PEI with small diacrylate (1,4-butanedioldiacrylate or ethyleneglycol dimethacrylate) for 2-6 hours. The efficiency of the cross-linkedPEIs during in vitro delivering plasmid containing enhanced green fluorescent protein(EGFP) gene reporter and their cytotoxicity were assessed in melanoma B16F10 cell andother cell lines. In vivo gene delivery efficiency was evaluated by direct injection delivery ofthe EGFP plasmid/ cross-linked PEI complexes into mice and by estimating the EGFPexpression in animal muscles. Compared to commercially available 25-kDa branched PEI,the cross-linked PEIs reported here could mediate more efficient expression of reporter genethan the 25-kDa PEI control, 19-fold more efficiently in B16F10 cells, 17-fold in 293T cells, 2.3-fold in 3T3 cells, and they exhibited essentially nontoxic at their optimized condition for gene delivery. Furthermore the transfection activity of polyplexs was preserved in the presence of serum proteins. The muscle transfected with the cross-linked PEI prepared here exhibited normal morphology and excellent gene expression. The cross-linked PEIs reported here were evidently more efficient than the commercial 25-kD PEI control and had less cytotoxicity in gene delivery in vitro and in vivo.
A DFT-Based QSARs Study of Acetazolamide/Sulfanilamide Derivatives with Carbonic Anhydrase (CA-II) Isozyme Inhibitory Activity
Authors: Eroğlu Erol , Türkmen Hasan , Güler Semra , Palaz Selami , Oltulu Oral
Published: October 2008

This study presents Quantitative Structure Activity Relationships (QSAR) studyon a pool of 18 bio-active sulfonamide compounds which includes five acetazolamidederivatives, eight sulfanilamide derivatives and five clinically used sulfonamides moleculesas drugs namely acetazolamide, methazolamide, dichlorophenamide, ethoxolamide anddorzolamide. For all the compounds, initial geometry optimizations were carried out with amolecular mechanics (MM) method using the MM force fields. The lowest energyconformations of the compounds obtained by the MM method were further optimized by theDensity Functional Theory (DFT) method by employing Becke’s three-parameter hybridfunctional (B3LYP) and 6-31G (d) basis set. Molecular descriptors, dipole moment,electronegativity, total energy at 0 K, entropy at 298 K, HOMO and LUMO energiesobtained from DFT calculations provide valuable information and have a significant role inthe assessment of carbonic anhydrase (CA-II) inhibitory activity of the compounds. By usingthe multiple linear regression technique several QSAR models have been drown up with thehelp these calculated descriptors and carbonic anhydrase (CA-II) inhibitory data of themolecules. Among the obtained QSAR models presented in the study, statistically the mostsignificant one is a five parameters linear equation with the squared correlation coefficient R2 values of ca. 0.94 and the squared cross-validated correlation coefficient R2CV values of ca. 0.85. The results were discussed in the light of the main factors that influence theinhibitory activity of the carbonic anhydrase (CA-II) isozyme.
Results from the Use of Molecular Descriptors Family on Structure Property/Activity Relationships
Authors: Jäntschi Lorentz , Bolboacă Sorana-Daniela
Published: October 2008

The aim of the paper is to present the results obtained by utilization of an originalapproach called Molecular Descriptors Family on Structure-Property (MDF-SPR) andStructure-Activity Relationships (MDF-SAR) applied on classes of chemical compoundsand its usefulness as precursors of models elaboration of new compounds with betterproperties and/or activities and low production costs. The MDF-SPR/MDF-SARmethodology integrates the complex information obtained from compound’s structure inunitary efficient models in order to explain properties/activities. The methodology has beenapplied on a number of thirty sets of chemical compounds. The best subsets of moleculardescriptors family members able to estimate and predict property/activity of interest wereidentified and were statistically and visually analyzed. The MDF-SPR/MDF-SAR modelswere validated through internal and/or external validation methods. The estimation andprediction abilities of the MDF-SPR/MDF-SAR models were compared with previousreported models by applying of correlated correlation analysis, which revealed that theMDF-SPR/MDF-SAR methodology is reliable. The MDF-SPR/MDF-SAR methodologyopens a new pathway in understanding the relationships between compound’s structure andproperty/activity, in property/activity prediction, and in discovery, investigation andcharacterization of new chemical compounds, more competitive as costs andproperty/activity, being a method less expensive comparative with experimental methods.
Crystal Engineering Based on Polymeric Hydrogen-Bonded Supramolecules by Self-Assembling of 9, 10-Bis(3,5- dihydroxyphenyl)anthracene and 2,2′,4,4′- Tetrahydroxybenzophenone with Bipyridines
Authors: Li Xiaokang , Zhen Lvyin , Fan Yulan , Fan Xiaolin , Zeng Qingdao
Published: October 2008

9, 10-bis(3,5-dihydroxyphenyl)anthracene (BDHA) and 2,2′,4,4′-tetrahydroxybenzophenone (THB) are crystallized with bipyridine bases 4,4 ́-bipyridyl(bipy), 1,2-bis(4-pyridyl)ethane (bipy-eta), 1,2-di(4-pyridyl)ethylene (dipy-ete), 1,3-di(4-pyridyl)propane (dipy-pra), 4,4 ́-dipyridyl sulfide (dipy-sul), and 4,4 ́-dipyridyl disulfide(dipy-dis) to afford molecular complexes (BDHA)·(bipy)2 1, (BDHA)·(bipy-eta)2 2,(BDHA)0.5·(dipy-pra)·CH3CH2OH 3, (BDHA)0.5·(dipy-sul)·H2O 4, (BDHA)0.5·(dipy-dis)·CH3CH2OH 5 and (THB)·(dipy-ete)2·H2O 6. The crystal structures of 1–6 have beendetermined by single-crystal X-ray diffraction. All these molecular complexes exhibitpolymeric supramolecular structures via O–H···N or O–H···O hydrogen-bonding. 1 and 2form infinitely rectangular macrocycles linked with one another, whose sizes are ca.12.477 å× 4.802 å and ca.14.575 å × 4.809 å, respectively. 3, 5 and 6 form the one-dimensionalzigzag chain structure. 4 forms a ladder structure, and two dipy-sul molecules were includedin a frame.
A Centrifugation-based Method for Preparation of Gold Nanoparticles and its Application in Biodetection
Authors: Liang Zhiqiang , Zhang Juan , Wang Lihua , Song Shiping , Fan Chunhai , Li Genxi
Published: October 2008

Gold nanoparticles (AuNPs) have found widespread applications in lifesciences. While synthesis of monodispersed AuNPs has been fairly convenient by usingchemical reduction of chloroauric acid by sodium citrate, we found that AuNPs of highquality and high concentrations were not readily obtained via this method. As an example,we showed that monodispersed 13-nm AuNPs were readily synthesized at relatively lowconcentrations (e.g. 3.5 nM); in contrast, 13-nm AuNPs of 17 nM obtained by the directreduction method were irregularly shaped and not well dispersed. In this work, wedemonstrated that AuNPs of high concentration could be prepared by a two-step approach,i.e. chemical reduction at low concentrations and subsequent centrifugation. Compared tothe direct reduction method, this new two-step method led to AuNPs with high saltresistance and high stability, which are essential for the preparation of DNA-AuNPsconjugates for DNA biodetection.
Drastic Attenuation of Pseudomonas aeruginosa Pathogenicity in a Holoxenic Mouse Experimental Model Induced by Subinhibitory Concentrations of Phenyllactic acid (PLA)
Authors: Chifiriuc Mariana–Carmen , Veronica Lazar , Dracea Olguta , Ditu Lia-Mara , Smarandache Diana , Bucur Marcela , Larion Cristina , Ramona Cernat , Sasarman Elena
Published: October 2008

The discovery of communication systems regulating bacterial virulence hasafforded a novel opportunity to control infectious bacteria without interfering withgrowth. In this paper we describe the effect of subinhibitory concentrations of phenyl-lactic acid (PLA) on the pathogenicity of Pseudomonas aeruginosa in mice. The animalswere inoculated by oral (p.o.), intranasal (i.n.), intravenous (i.v.) and intraperitoneal (i.p.)routes with P. aeruginoasa wild and PLA-treated cultures. The mice were followed upduring 16 days after infection and the body weight, mortality and morbidity rate weremeasured every day. The microbial charge was studied by viable cell counts in lungs,spleen, intestinal mucosa and blood. The mice batches infected with wild P. aeruginosabacterial cultures exhibited high mortality rates (100 % after i.v. and i.p. route) and veryhigh cell counts in blood, lungs, intestine and spleen. In contrast, the animal batchesinfected with PLA treated bacterial cultures exhibited good survival rates (0 % mortality) and the viable cell counts in the internal organs revealed with one exception the complete abolition of the invasive capacity of the tested strains. In this study, using a mouse infection model we show that D-3-phenyllactic acid (PLA) can act as a potent antagonist of Pseudomonas (P.) aeruginosa pathogenicity, without interfering with the bacterial growth, as demonstrated by the improvement of the survival rates as well as the clearance of bacterial strains from the body.
Catalytic Ring Hydrogenation of Benzoic Acid with Supported Transition Metal Catalysts in scCO2
Authors: Wang Hongjun , Zhao Fengyu
Published: October 2008

The ring hydrogenation of benzoic acid to cyclohexanecarboxylic acid overcharcoal-supported transition metal catalysts in supercritical CO2 medium has been studiedin the present work. The cyclohexanecarboxylic acid can be produced efficiently insupercritical CO2 at the low reaction temperature of 323 K. The presence of CO2 increasesthe reaction rate and several parameters have been discussed.
Salting-out in Aqueous Solutions of Ionic Liquids and K3PO4: Aqueous Biphasic Systems and Salt Precipitation
Authors: Najdanovic-Visak Vesna , Lopes José N. Canongia , Visak Zoran P. , Trindade J. , Rebelo Luís P. N.
Published: October 2008

The salting-out effect produced by the addition of potassium phosphate, K3PO4to aqueous solutions of water-miscible ionic liquids, viz. 1-ethyl-3-methylimidazoliumethyl sulfate, 1-butyl-3-methylimidazolium methyl sulfate, or 1-alkyl-3-methylimidazolium chloride (alkyl = butyl, octyl or decyl) is investigated. The effects areanalyzed using both the corresponding temperature–composition pseudo-binary andcomposition ternary phase diagrams. Different regions of liquid-liquid and solid-liquidphase demixing are mapped. The phase behavior is interpreted taking into account thecomplex and competing nature of the interactions between the ionic liquid, the inorganicsalt and water. In the case of solutions containing 1-octyl- or 1-decyl-3-methylimidazoliumchloride, the smaller magnitude of the salting-out effects is explained in terms of thepossibility of self-aggregation of the ionic liquid.
Protective Effect of Encapsulation in Fermentation of Limonene-contained Media and Orange Peel Hydrolyzate
Authors: Pourbafrani Mohammad , Talebnia Farid , Niklasson Claes , Taherzadeh Mohammad J.
Published: October 2008

This work deals with the application of encapsulation technology to eliminateinhibition by D-limonene in fermentation of orange wastes to ethanol. Orange peel wasenzymatically hydrolyzed with cellulase and pectinase. However, fermentation of thereleased sugars in this hydrolyzate by freely suspended S. cerevisiae failed due to inhibitionby limonene. On the other hand, encapsulation of S. cerevisiae in alginate membranes wasa powerful tool to overcome the negative effects of limonene. The encapsulated cells wereable to ferment the orange peel hydrolyzate in 7 h, and produce ethanol with a yield of 0.44g/g fermentable sugars. Cultivation of the encapsulated yeast in defined medium wassuccessful, even in the presence of 1.5% (v/v) limonene. The capsules’ membranes wereselectively permeable to the sugars and the other nutrients, but not limonene. While1% (v/v) limonene was present in the culture, its concentration inside the capsules was notmore than 0.054% (v/v).
Molecular Mechanics Study of Nickel(II) Octaethylporphyrin Adsorbed on Graphite(0001)
Authors: Gruden-Pavlović Maja , Grubišić Sonja , Zlatar Matija , Niketić Svetozar R.
Published: October 2008

The effects of adsorption on the graphite(0001) surface on the nonplanar dis-tortions of nickel(II)octaethylporphyrin were studied by molecular mechanics (MM) ap-proach. Using the Consistent Force Field (CFF) program with previously developed pa-rameters for metalloporphyrins and supplemented to treat intermolecular interactions ge-ometry optimizations were carried out for 43 conformations of 28 distinct conformers ofnickel(II)octaethylporphyrin. The stable energy-minimized conformers were stereochem-ically characterized, analyzed by the Normal-coordinate Structural Decomposition (NSD)method and compared with the available theoretical and experimental data for the isolatednickel(II)octaethylporphyrin structures.
Dietary Polyphenols and Their Biological Significance
Authors: Han Xiuzhen , Shen Tao , Lou Hongxiang
Published: October 2008

Dietary polyphenols represent a wide variety of compounds that occur in fruits,vegetables, wine, tea, extra virgin olive oil, chocolate and other cocoa products. They aremostly derivatives and/or isomers of flavones, isoflavones, flavonols, catechins andphenolic acids, and possess diverse biological properties such as antioxidant, antiapoptosis,anti-aging, anticarcinogen, anti-inflammation, anti-atherosclerosis, cardiovascularprotection, improvement of the endothelial function, as well as inhibition of angiogenesisand cell proliferation activity. Most of these biological actions have been attributed to theirintrinsic reducing capabilities. They may also offer indirect protection by activatingendogenous defense systems and by modulating cellular signaling processes such asnuclear factor-kappa B (NF-кB) activation, activator protein-1(AP-1) DNA binding,glutathione biosynthesis, phosphoinositide 3 (PI3)-kinase/protein kinase B (Akt) pathway,mitogen-activated protein kinase (MAPK) proteins [extracellular signal-regulated proteinkinase (ERK), c-jun N-terminal kinase (JNK) and P38 ] activation, and the translocationinto the nucleus of nuclear factor erythroid 2 related factor 2 (Nrf2). This paper covers themost recent literature on the subject, and describes the biological mechanisms of action andprotective effects of dietary polyphenols.
A Fragment-Based Scoring Function to Re-rank ATP Docking Results
Authors: Pyrkov Timothy V. , Efremov Roman G.
Published: October 2008

ATP is involved in numerous biochemical reactions in living cells interacting withdifferent proteins. Molecular docking simulations provide considerable insight into theproblem of molecular recognition of this substrate. To improve the selection of correctATP poses among those generated by docking algorithms we propose a post-docking rerankingcriterion. The method is based on detailed analysis of the intermolecularinteractions in 50 high-resolution 3D-structures of ATP-protein complexes. A distinctivenew feature of the proposed method is that the ligand molecule is divided into fragmentsthat differ in their physical properties. The placement of each of them into the bindingsite is judged separately by different criteria, thus avoiding undesirable averaging of thescoring function terms by highlighting those relevant for particular fragments. Thescoring performance of the new criteria was tested with the docking solutions for ATPproteincomplexes and a significant improvement in the selection of correct dockingposes was observed, as compared to the standard scoring function.
Analysis of Phenacylester Derivatives of Fatty Acids from Human Skin Surface Sebum by Reversed-Phase HPLC: Chromatographic Mobility as a Function of Physico-Chemical Properties
Authors: Bodoprost Juliana , Rosemeyer Helmut
Published: October 2008

A set of 13 fatty acids was transformed into their phenacyl esters by reaction withphenacyl bromide in acetonitrile using 18-crown-6 as phase-transfer catalyst. Conditions forthe RP-18 HPL chromatographic separation of most of the esters has been worked out.Using this standard the fatty acid spectra from skin surface sebum lipids of 17 test personswas taken after microwave-assisted hydrolysis, neutralization and extraction with n-hexane.Quantitative evaluation of the chromatograms exhibits that oleic acid predominates in thesebum of all test persons. In the second part of the work the chromatographic mobility (REvalues) of fatty acid phenacyl esters is correlated with calculated physico-chemicalparameters of the corresponding acids. The best linear correlation was found between the REand the logP values. This is helpful for the structural elucidation of un-identified fatty acidsin a chromatogram.
Inhibition of Acetylcholinesterase in Different Structures of the Rat Brain Following Soman Intoxication Pretreated with Huperzine A
Authors: Bajgar Jiri , Hajek Petr , Karasova Jana , Slizova Dasa , Krs Otakar , Kuca Kamil , Jun Daniel , Fusek Josef , Capek Lukas
Published: October 2008

Acetylcholinesterase (AChE) activities in different brain parts were determinedquantitatively in rats treated with huperzine A, soman, and huperzine A followed bysoman, using histochemical and biochemical methods. Following soman intoxication (1.2x LD50, i.m.), AChE activity was decreased to 30-80% of control values depending on thebrain structure. The most sensitive area was the frontal cortex and the most relativelyresistant was ncl. ruber. Huperzine A treatment only caused a change in AChE activityvarying from 70 to 100 % of control values. In rats pretreated with huperzine A andintoxicated with soman, AChE activity was significantly higher than that observed aftersoman. In these animals, survival of rats pretreated with huperzine was observed whilethe mortality of unpretreated animals was near to 80 %. The results suggest that huperzineA is good candidate for further study for clinical use as a prophylactic drug against nerveagent poisoning.
Mechanism of Growth Inhibition of Human Cancer Cells by Conjugated Eicosapentaenoic Acid, an Inhibitor of DNA Polymerase and Topoisomerase
Authors: Yonezawa Yuko , Yoshida Hiromi , Mizushina Yoshiyuki
Published: October 2008

DNA topoisomerases (topos) and DNA polymerases (pols) are involved in manyaspects of DNA metabolism such as replication reactions. We found that long chainunsaturated fatty acids such as polyunsaturated fatty acids (PUFA) (i.e., eicosapentaenoicacid (EPA) and docosahexaenoic acid (DHA)) inhibited the activities of eukaryotic pols andtopos in vitro, and the inhibitory effect of conjugated fatty acids converted from EPA andDHA (cEPA and cDHA) on pols and topos was stronger than that of normal EPA and DHA.cEPA and cDHA did not affect the activities of plant and prokaryotic pols or other DNAmetabolic enzymes tested. cEPA was a stronger inhibitor than cDHA with IC50 values formammalian pols and human topos of 11.0 - 31.8 and 0.5 - 2.5 μM, respectively. cEPAinhibited the proliferation of two human leukemia cell lines, NALM-6, which is a p53-wildtype, and HL-60, which is a p53-null mutant, and the inhibitory effect was stronger than thatof normal EPA. In both cell lines, cEPA arrested in the G1 phase, and increased cyclin Eprotein levels, indicating that it blocks the primary step of in vivo DNA replication byinhibiting the activity of replicative pols rather than topos. DNA replication-relatedproteins, such as RPA70, ATR and phosphorylated-Chk1/2, were increased by cEPAtreatment in the cell lines, suggesting that cEPA led to DNA replication fork stressinhibiting the activities of pols and topos, and the ATR-dependent DNA damage response pathway could respond to the inhibitor of DNA replication. The compound induced cellapoptosis through both p53-dependent and p53-independent pathways in cell lines NALM-6and HL-60, respectively. These results suggested the therapeutic potential of conjugatedPUFA, such as cEPA, as a leading anti-cancer compound that inhibited pols and toposactivities.
Accelerator Analysis of Tributyltin Adsorbed onto the Surface of a Tributyltin Resistant Marine Pseudoalteromonas sp. Cell
Authors: Mimura Haruo , Sato Ryusei , Sasaki Yu , Furuyama Yuichi , Taniike Akira , Yoshida Kazutoshi , Kitamura Akira
Published: October 2008

Tributyltin (TBT) released into seawater from ship hulls is a stable marine pollutant and obviously remains in marine environments. We isolated a TBT resistant marine Pseudoalteromonas sp. TBT1 from sediment of a ship’s ballast water. The isolate (109.3 ± 0.2 colony-forming units mL-1) adsorbed TBT in proportion to the concentrations of TBTCl externally added up to 3 mM, where the number of TBT adsorbed by a single cell was estimated to be 108.2. The value was reduced to about one-fifth when the lysozyme-treated cells were used. The surface of ethanol treated cells became rough, but the capacity of TBT adsorption was the same as that for native cells. These results indicate that the function of the cell surface, rather than that structure, plays an important role to the adsorption of TBT. The adsorption state of TBT seems to be multi-layer when the number of more than 106.8 TBT molecules is adsorbed by a single cell.
Preparation and Characterization of Highly Fluorescent, Glutathione-coated Near Infrared Quantum Dots for in Vivo Fluorescence Imaging
Authors: Jin Takashi , Fujii Fumihiko , Komai Yutaka , Seki Junji , Seiyama Akitoshi , Yoshioka Yoshichika
Published: October 2008

Fluorescent probes that emit in the near-infrared (NIR, 700-1,300 nm) region are suitable as optical contrast agents for in vivo fluorescence imaging because of low scattering and absorption of the NIR light in tissues. Recently, NIR quantum dots (QDs) have become a new class of fluorescent materials that can be used for in vivo imaging. Compared with traditional organic fluorescent dyes, QDs have several unique advantages such as size- and composition-tunable emission, high brightness, narrow emission bands, large Stokes shifts, and high resistance to photobleaching. In this paper, we report a facile method for the preparation of highly fluorescent, water-soluble glutathione (GSH)-coated NIR QDs for in vivo imaging. GSH-coated NIR QDs (GSH-QDs) were prepared by surface modification of hydrophobic CdSeTe/CdS (core/shell) QDs. The hydrophobic surface of the CdSeTe/CdS QDs was exchanged with GSH in tetrahydrofuran-water. The resulting GSH-QDs were monodisperse particles and stable in PBS (phosphate buffered saline, pH = 7.4). The GSH-QDs (800 nm emission) were highly fluorescent in aqueous solutions (quantum yield = 22% in PBS buffer), and their hydrodynamic diameter was less than 10 nm, which is comparable to the size of proteins. The cellular uptake and viability for the GSH-QDs were examined using HeLa and HEK 293 cells. When the cells were incubated with aqueous solutions of the GSH-QDs (10 nM), the QDs were taken into the cells and distributed in the perinuclear region of both cells. After 12 hrs incubation of 4 nM of GSH-QDs, the viabilities of HeLa and HEK 293 cells were ca. 80 and 50%, respectively. As a biomedical utility of the GSH-QDs, in vivo NIRfluorescence imaging of a lymph node in a mouse is presented.
NeuroMEMS: Neural Probe Microtechnologies
Authors: HajjHassan Mohamad , Chodavarapu Vamsy , Musallam Sam
Published: October 2008

Neural probe technologies have already had a significant positive effect on our understanding of the brain by revealing the functioning of networks of biological neurons. Probes are implanted in different areas of the brain to record and/or stimulate specific sites in the brain. Neural probes are currently used in many clinical settings for diagnosis of brain diseases such as seizers, epilepsy, migraine, Alzheimer’s, and dementia. We find these devices assisting paralyzed patients by allowing them to operate computers or robots using their neural activity. In recent years, probe technologies were assisted by rapid advancements in microfabrication and microelectronic technologies and thus are enabling highly functional and robust neural probes which are opening new and exciting avenues in neural sciences and brain machine interfaces. With a wide variety of probes that have been designed, fabricated, and tested to date, this review aims to provide an overview of the advances and recent progress in the microfabrication techniques of neural probes. In addition, we aim to highlight the challenges faced in developing and implementing ultralong multi-site recording probes that are needed to monitor neural activity from deeper regions in the brain. Finally, we review techniques that can improve the biocompatibility of the neural probes to minimize the immune response and encourage neural growth around the electrodes for long term implantation studies.
Linear FBG Temperature Sensor Interrogation with Fabry-Perot ITU Multi-wavelength Reference
Authors: Park Hyoung-Jun , Song Minho
Published: October 2008

The equidistantly spaced multi-passbands of a Fabry-Perot ITU filter are used as an efficient multi-wavelength reference for fiber Bragg grating sensor demodulation. To compensate for the nonlinear wavelength tuning effect in the FBG sensor demodulator, a polynomial fitting algorithm was applied to the temporal peaks of the wavelength-scanned ITU filter. The fitted wavelength values are assigned to the peak locations of the FBG sensor reflections, obtaining constant accuracy, regardless of the wavelength scan range and frequency. A linearity error of about 0.18% against a reference thermocouple thermometer was obtained with the suggested method.
Bancos de imágenes y sonido y motores de indización en la www
Authors: Codina Bonilla Lluís , Del Valle Palma Maria
Published: October 2008

La documentación audiovisual experimenta un importante crecimiento cualitativo y cuantitativo gracias, entre otros factores, a las nuevas facilidades de difusión de la información que proporciona la WWW. Es de esperar que nuevos actores, como museos, filmotecas y archivos, se sumarán al sector de la producción y la distribución de los bancos de imagen y sonido. En este trabajo se presenta un panorama del sector de la documentación audiovisual en Internet.
Patrones de citación en la investigación española sobre evaluación de programas educativos (1975-200)
Authors: Fernández Cano Antonio , Expósito López Jorge
Published: October 2008

Este estudio es una revisión cienciométrica que trata de sintetizar, utilizando indicadores de citación, las realizaciones de la investigación educativa española sobre evaluación de programas educativos durante el periodo 1975-2000. Tras asumir un isomorfismo entre investigación y publicación de su informe como artículo en revistas especializadas, se parte de una búsqueda de tales informes fundamentalmente en la base de datos del ISOC/CSIC (Instituto de Información y Documentación en Ciencias Sociales y Humanidades), complementada con búsquedas cruzadas manuales, para realizar la revisión de 138 estudios recuperados y publicados como artículos de investigación en revistas científicas españolas del campo de la Educación. Al efecto, se elaboran y examinan una serie de indicadores cientimétricos de citación, que permiten inferir ciertas consideraciones sobre la evaluación de programas educativos en este campo y periodo.
Enfoque bibliométrico de la producción científica en ciencias de la salud en Puerto Rico a través de la base de datos Science Citation Index durante el período de 1990 a 1998
Authors: Ortiz Rivera Laurie , Suárez Balseiro Carlos , Sanz Casado Elías
Published: October 2008

Este trabajo identifica y expone algunas características de la producción científica en ciencias de la salud de instituciones radicadas en Puerto Rico durante el período de 1990 a 1998, utilizando para ello la base de datos del Science Citation Index (SCI), producida por el Institute for Scientific Information (ISI) de Filadelfia. Han sido utilizados indicadores bibliométricos unidimensionales y multidimensionales para mostrar su evolución en el tiempo. Se ha comprobado el aumento de la producción de los grupos de investigación en la isla en el área de ciencias de la salud, identificándose las principales áreas de investigación, así como algunos aspectos relacionados con la colaboración entre investigadores a nivel nacional e internacional. Además, se comprueba que la visibilidad de la investigación es alta y se exponen los hábitos en cuanto a la tipología documental y el idioma en que los investigadores dan a conocer su trabajo, así como las revistas más utilizadas para publicarlos.
La biblioteca de la Universidade da Coruña. Estudio con los alumnos
Authors: Perea Vega Gustavo
Published: October 2008

Los tiempos cambian y con ellos el uso que se está haciendo de la biblioteca universitaria, que ha pasado de ser centro de consulta bibliográfica a emplearse principalmente como sala de estudio. Se hace necesario conocer los hábitos de uso de los usuarios para llevar a cabo una adecuada atención de sus demandas y contribuir a facilitar la gestión de los diferentes implicados en las políticas bibliotecarias. En esta línea se encamina este trabajo que presentamos.
Revistas científicas españolas con factor de impacto en el año 2000
Authors: Bordons María , Felipe Alicia , Gómez Isabel
Published: October 2008

Se analizan 31 revistas españolas de amplia visibilidad internacional, que aparecen con factor de impacto en el Journal Citation Reports del año 2000. Los aspectos estudiados incluyen: a) tamaño y estabilidad de la revista, analizado a través del número de documentos al año, frecuencia de publicación y antigüedad; b) tipo de editorial (pública o privada); c) proyección internacional, estudiada a través del idioma, presencia de comité editorial internacional y porcentaje de documentos extranjeros; d) impacto, a través del factor de impacto y la posición normalizada; y e) hábitos de citación, que incluye el porcentaje de autocitación y de autoreferencias de las revistas. Entre las revistas analizadas predominan las del área médica, las de pequeño tamaño y las de baja periodicidad. La mayor proyección internacional de las revistas se asocia a áreas de carácter básico, idioma inglés, presencia de comité científico internacional y factor de impacto más elevado. Las revistas españolas muestran menores tasas de autorreferencias y mayores tasas de autocitación que revistas de referencia europeas. El número de citas externas recibidas por las revistas es el factor que mejor explica la inclusión de las revistas en el Science Citation Index.
El sistema de revisión por expertos (peer review): muchos problemas y pocas soluciones
Authors: Campanario Juan Miguel
Published: October 2008

En este trabajo se revisan algunos de los problemas del sistema de revisión por expertos (peer review) y se analizan algunas de las posibles soluciones y alternativas al mismo.