bluuebunny/crossref_metadata_2025_split huggingface dataset:
NMR and Modeling Studies of Protein–Carbohydrate Interactions: Synthesis, Three‐Dimensional Structure, and Recognition Properties of a Minimum Hevein Domain with Binding Affinity for Chitooligosaccharides
Authors: Aboitiz Nuria , Vila‐Perelló Miquel , Groves Patrick , Asensio Juan Luis , Andreu David , Cañada Francisco Javier , Jiménez‐Barbero Jesús 
Published: September 2004

AbstractHEV32, a 32‐residue, truncated hevein lacking eleven C‐terminal amino acids, was synthesized by solid‐phase methodology and correctly folded with three cysteine bridge pairs. The affinities of HEV32 for small chitin fragments—in the forms of N,N′,N′′‐triacetylchitotriose ((GlcNAc)3) (millimolar) and N,N′,N′′,N′′′,N′′′′,N′′′′′‐hexaacetylchitohexaose ((GlcNAc)6) (micromolar)—as measured by NMR and fluorescence methods, are comparable with those of native hevein. The HEV32 ligand‐binding process is enthalpy driven, while entropy opposes binding. The NMR structure of ligand‐bound HEV32 in aqueous solution was determined to be highly similar to the NMR structure of ligand‐bound hevein. Solvated molecular‐dynamics simulations were performed in order to monitor the changes in side‐chain conformation of the binding site of HEV32 and hevein upon interaction with ligands. The calculations suggest that the Trp21 side‐chain orientation of HEV32 in the free form differs from that in the bound state; this agrees with fluorescence and thermodynamic data. HEV32 provides a simple molecular model for studying protein–carbohydrate interactions and for understanding the physiological relevance of small native hevein domains lacking C‐terminal residues.
Disaccharide Mimetics of the Aminoglycoside Antibiotic Neamine
Authors: Venot Andre , Swayze Eric E. , Griffey Richard H. , Boons Geert‐Jan 
Published: September 2004

AbstractA highly convergent approach has been employed for the facile synthesis of a library of 24 disaccharides that are α(1–3), β(1–3), α(1–4), or β(1–4) linked and contain 2–4 amino groups. Fourier‐transformation ion cyclotron resonance mass spectrometry (FT‐ICR MS) has been used to determine dissociation constant (Kd) values for the binding of the disaccharides to a prototypical fragment of 16S ribosomal RNA. Several derivatives bound with affinities similar to that of neamine. Structure–activity relationships have revealed the substitution pattern that is important for high‐affinity binding. The compounds described here are unique lead compounds for the design of novel aminoglycoside antibiotics.
Fusarin C Biosynthesis in Fusarium moniliforme and Fusarium venenatum
Authors: Song Zhongshu , Cox Russell J. , Lazarus Colin M. , Simpson Thomas J. 
Published: September 2004

AbstractFragments of polyketide synthase (PKS) genes were amplified from complementary DNA (cDNA) of the fusarin C producing filamentous fungi Fusarium moniliforme and Fusarium venenatum by using degenerate oligonucleotides designed to select for fungal PKS C‐methyltransferase (CMeT) domains. The PCR products, which were highly homologous to fragments of known fungal PKS CMeT domains, were used to probe cDNA and genomic DNA (gDNA) libraries of F. moniliforme and F. venenatum. A 4.0 kb cDNA clone from F. venenatum was isolated and used to prepare a hygromycin‐resistance knockout cassette, which was used to produce a fusarin‐deficient strain of F. venenatum (kb=1000 bp). Similarly, a 26 kb genomic fragment, isolated on two overlapping clones from F. moniliforme, encoded a complete iterative Type I PKS fused to an unusual nonribosomal peptide synthase module. Once again, targeted gene disruption produced a fusarin‐deficient strain, thereby proving that this synthase is responsible for the first steps of fusarin biosynthesis.
A Computational Fluid Dynamics Study of Binary Adsorption Separation in Chromatography
Authors: Wu Y.X. , Yu H.W. , Ching C.B. 
Published: September 2004

AbstractFEMLAB software was applied to incorporate computational fluid dynamics (CFD) into the simulation of the adsorption‐separation process in chromatography. Simulations of both linear and nonlinear processes demonstrated that significant dispersion retarded the separation processes, and that a small inlet induced curved solute concentration profiles, resulting in peak tailing of the elution chromatogram. The linear simulation visually confirmed that a small Stanton number might be another factor for peak tailing. For cases with a reasonably small Stanton number, peak tailing became more serious with decreasing Stanton number. Comparisons between the results of the CFD simulation of the nonlinear case, the corresponding conventional 1‐D simulation and the experimental result lead to the conclusion that the CFD simulation is useful for a better understanding of the dynamic adsorption and separation process in a chromatographic column.
Investigation of Fluid and Coarse‐Particle Dynamics in a Two‐Dimensional Spouted Bed
Authors: Swasdisevi T. , Tanthapanichakoon W. , Charinpanitkul T. , Kawaguchi T. , Tanaka T. , Tsuji Y. 
Published: September 2004

AbstractThe aerodynamics of particles and gas flow in a two‐dimensional spouted bed (2DSB) with draft plates is investigated with the aid of the discrete element method. The geometry of the 2DSB with draft plates is set as close as possible to the experimental apparatus of Kudra [1] and Kalwar [2]. The physical properties of the coarse particles are similar to those of shelled corn. The calculated minimum spouting velocity and pressure drop agree well with the correlations of Kudra [1] and Kalwar [2]. In the spout region, the particle vertical velocities are found to decrease as the height increases. The fluid velocity in the downcomer region decreases as the superficial gas velocity increases. The particle circulation rate increases when the friction coefficient decreases or the separation height increases. At the minimum spouting velocity, the bed height does not affect the particle circulation rate in the 2DSB with draft plates. The draft plates not only reduce the minimum spouting velocity and pressure drop but also increase the maximum spoutable bed height. The effect of taking out the draft plates on the spouting phenomenon is investigated and the effect of putting in a deflector on the possible breakage of the particles is also estimated.
Effect of Dual Impeller‐Sparger Geometry on the Hydrodynamics and Mass Transfer in Stirred Vessels
Authors: García‐Cortés D. , Xuereb C. , Taillandier P. , Jáuregui‐Haza U. , Bertrand J. 
Published: September 2004

AbstractThe understanding of the effect of impeller‐sparger configurations on gas dispersion and mass transfer is very important to improve the performance of gas/liquid contactor systems. The influence of the impeller positions, the upper turbine diameter, the sparger ring diameter and its location in regard to the lower impeller on the power consumption, the volumetric mass‐transfer coefficient and the overall oxygen transfer efficiency were studied in a nonstandard curved bottomed reactor with an agitated system with dual disk style turbines. In the range of the gas flow rates studied, the most efficient impeller‐sparger arrangement for the oxygen transfer is the impeller system with turbines of different diameters located at C = 0.25 and IC = 0.5, and with the sparger of smaller diameter than the lower impeller settled below the impeller. A new model to estimate the kLa with an average relative error of 8 %, which takes the reactor operation conditions and the influence of the impeller‐sparger geometry into account, was also proposed.
Combination of CFD and Chemical Reactions for Process Engineering
Authors: Heggemann M. , Wintergerste T. 
Published: September 2004

AbstractIn process engineering chemical reactions may be classified in gas‐phase chemistry, liquid‐phase chemistry, and surface chemistry. The latter is essential for the description of heterogeneous catalytic operations. Furthermore, simulations often have to treat reversible reactions and kinetically controlled processes. This paper provides a brief overview of the methodologies, trends, and limits. Three methods are tested for coping with the different challenges of the individual characters of chemical reactions: the CHEMKIN Collection, STAR‐CD, and STAR‐CD/KINetics (= STAR‐CD + CHEMKIN). The results show that the capacity of a tool depends very much on the requirements and specifications of the chemical reactions.
Stability of Dispersions
Authors: Bellmann C. 
Published: September 2004

AbstractThe importance of the production and application of disperse systems in industry is steadily growing, while colloidal systems surround us every day (for example foodstuffs, pharmaceuticals etc.). Understanding the forces and mechanisms of interaction allows the development of new materials and improvement of available systems. The stability of such systems is one of the central research points. One of the well‐known physical models of colloid stability is given by DLVO‐Theory. With this theory we have a tool to influence the stability of such dispersion systems. In this paper, electrokinetic methods are used to investigate interaction forces in disperse systems. The influence of pH‐value, electrolyte concentration and valency is shown with suitable examples. However, in some cases the DLVO‐model is not satisfactory, and reasons for this behavior will also be discussed.
Modulation of the Absorption, Fluorescence, and Liquid‐Crystal Properties of Functionalised Diarylethene Derivatives
Authors: Frigoli Michel , Mehl Georg H. 
Published: September 2004

AbstractSystematic variation of the molecular symmetry in a photochromic system based on a 1,2‐bis(2‐methylbenzo[b]thiophen‐3‐yl)hexafluorocyclopentene group, connected by decyl spacers to two cyanobiphenyl groups as mesogens, allows for a systematic investigation of the correlations between molecular shape and symmetry, electronic effects, photochromic conversion and liquid‐crystalline properties.
NMR Parameters and Geometries of OHN and ODN Hydrogen Bonds of Pyridine–Acid Complexes
Authors: Limbach Hans‐Heinrich , Pietrzak Mariusz , Sharif Shasad , Tolstoy Peter M. , Shenderovich Ilya G. , Smirnov Sergei N. , Golubev Nikolai S. , Denisov Gleb S. 
Published: September 2004

AbstractIn this paper, equations are proposed which relate various NMR parameters of OHN hydrogen‐bonded pyridine–acid complexes to their bond valences which are in turn correlated with their hydrogen‐bond geometries. As the valence bond model is strictly valid only for weak hydrogen bonds appropriate empirical correction factors are proposed which take into account anharmonic zero‐point energy vibrations. The correction factors are different for OHN and ODN hydrogen bonds and depend on whether a double or a single well potential is realized in the strong hydrogen‐bond regime. One correction factor was determined from the known experimental structure of a very strong OHN hydrogen bond between pentachlorophenol and 4‐methylpyridine, determined by the neutron diffraction method. The remaining correction factors which allow one also to describe H/D isotope effects on the NMR parameters and geometries of OHN hydrogen bond were determined by analysing the NMR parameters of the series of protonated and deuterated pyridine‐ and collidine–acid complexes. The method may be used in the future to establish hydrogen‐bond geometries in biologically relevant functional OHN hydrogen bonds.
New Routes to Polymetallic Clusters: Fluoride‐Based Tri‐, Deca‐, and Hexaicosametallic MnIII Clusters and their Magnetic Properties
Authors: Jones Leigh F. , Rajaraman Gopalan , Brockman Jonathon , Murugesu Muralee , San̂udo E. Carolina , Raftery Jim , Teat Simon J. , Wernsdorfer Wolfgang , Christou George , Brechin Euan K. , Collison David 
Published: September 2004

AbstractThe syntheses, structures and magnetic properties of three new MnIII clusters, [Mn26O17(OH)8(OMe)4F10(bta)22(MeOH)14(H2O)2] (1), [Mn10O6(OH)2(bta)8(py)8F8] (2) and [NHEt3]2[Mn3O(bta)6F3] (3), are reported (bta=anion of benzotriazole), thereby demonstrating the utility of MnF3 as a new synthon in Mn cluster chemistry. The “melt” reaction (100 °C) between MnF3 and benzotriazole (btaH, C6H5N3) under an inert atmosphere, followed by dissolution in MeOH produces the cluster [Mn26O17(OH)8(OMe)4F10(bta)22(MeOH)14(H2O)2] (1) after two weeks. Complex 1 crystallizes in the triclinic space group P$\bar 1$, and consists of a complicated array of metal tetrahedra linked by μ3‐O2− ions, μ3‐ and μ2‐OH− ions, μ2‐MeO− ions and μ2‐bta− ligands. The “simpler” reaction between MnF3 and btaH in boiling MeOH (50 °C) also produces complex 1. If this reaction is repeated in the presence of pyridine, the decametallic complex [Mn10O6(OH)2(bta)8(py)8F8] (2) is produced. Complex 2 crystallizes in the triclinic space group P$\bar 1$ and consists of a “supertetrahedral” [MnIII10] core bridged by six μ3‐O2− ions, two μ3‐OH− ions, four μ2‐F− ions and eight μ2‐bta− ions. The replacement of pyridine by triethylamine in the same reaction scheme produces the trimetallic species [NHEt3]2[Mn3O(bta)6F3] (3). Complex 3 crystallises in the monoclinic space group P21/c and has a structure analogous to that of the basic metal carboxylates of general formula [M3O(RCO2)6L3]0/+, which consists of an oxo‐centred metal triangle with μ2‐bta− ligands bridging each edge of the triangle and the fluoride ions acting as the terminal ligands. DC magnetic susceptibility measurements in the 300–1.8 K and 0.1–7 T ranges were investigated for all three complexes. For each, the value of χMT decreases with decreasing temperatures; this indicates the presence of dominant antiferromagnetic exchange interactions in 1–3. For complex 1, the low‐temperature value of χMT is 10 cm3 K mol−1 and fitting of the magnetisation data gives S=4, g=2.0 and D=−0.90 cm−1. For complex 2, the value of χMT falls to a value of approximately 5.0 cm3 K mol−1 at 1.8 K, which is consistent with a small spin ground state. For the triangular complex 3, the best fit to the experimental χMT versus T data was obtained for the following parameters: Ja=−5.01 cm−1, Jb=+9.16 cm−1 and g=2.00, resulting in an S=2 spin ground state. DFT calculations on 3, however, suggest an S=1 or S=0 ground state with Ja=−2.95 cm−1 and Jb=−2.12 cm−1. AC susceptibility measurements performed on 1 in the 1.8–4.00 K range show the presence of out‐of‐phase AC susceptibility signals, but no peaks. Low‐temperature single‐crystal studies performed on 1 on an array of micro‐SQUIDS show the time‐ and temperature‐dependent hysteresis loops indicative of single‐molecule magnetism behaviour.
Acid–Base Properties of Xanthosine 5′‐Monophosphate (XMP) and of Some Related Nucleobase Derivatives in Aqueous Solution: Micro Acidity Constant Evaluations of the (N1)H versus the (N3)H Deprotonation Ambiguity
Authors: Massoud Salah S. , Corfù Nicolas A. , Griesser Rolf , Sigel Helmut 
Published: September 2004

AbstractThe first acidity constant of fully protonated xanthosine 5′‐monophosphate, that is, of H3(XMP)+, was estimated by means of a micro acidity constant scheme and the following three deprotonations of the H2(XMP)± (pKa=0.97), H(XMP)− (5.30), and XMP2− (6.45) species were determined by potentiometric pH titrations; further deprotonation of (XMP−H)3− is possible only with pKa>12. The most important results are that the xanthine residue is deprotonated before the P(O)2(OH)− group loses its final proton; that is, twofold negatively charged XMP carries one negative charge in the pyrimidine ring and one at the phosphate group. Micro acidity constant evaluations reveal that this latter mentioned species occurs with a formation degree of 88 %, whereas its tautomer with a neutral xanthine moiety and a PO32− group is formed only to 12 %; this distinguishes XMP from its related nucleoside 5′‐monophosphates, like guanosine 5′‐monophosphate. At the physiological pH of about 7.5 mainly (XMP−H)3− exists. The question, which of the purine sites, (N1)H or (N3)H, is deprotonated in this species cannot be answered unequivocally, though it appears that the (N3)H site is more acidic. By application of several methylated xanthine species intrinsic micro acidity constants are calculated and it is shown that, for example, for 7‐methylxanthine the N1‐deprotonated tautomer occurs with a formation degree of about 5 %; a small but significant amount that, as is discussed, may possibly be enhanced by metal ion coordination to N7, which is known to occur preferably to this site.
Palladium‐Catalyzed Ring Expansion Reaction of (Z)‐1‐(1,3‐Butadienyl)cyclobutanols with Aryl Iodides. Stereospecific Synthesis of (Z)‐2‐(3‐Aryl‐1‐propenyl)cyclopentanones.
Authors: Yoshida Masahiro , Sugimoto Kenji , Ihara Masataka 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of Highly 1,3‐Proton Shift Transferable N‐Benzyl Imines of Trifluoroacetophenone under the “Low‐Basicity” Reaction Conditions.
Authors: Berbasov Dmitrii O. , Ojemaye Ifeyinwa D. , Soloshonok Vadim A. 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Simple Preparation of 7‐Alkylamino‐2‐methylquinoline‐5,8‐diones: Regiochemistry in Nucleophilic Substitution Reactions of the 6‐ or 7‐Bromo‐2‐methylquinoline‐5,8‐dione with Amines.
Authors: Choi Han Young , Chi Dae Yoon 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Design, Synthesis, and Structure—Activity Relationships of Pyrazolo[3,4‐d]pyrimidines: A Novel Class of Potent Enterovirus Inhibitors.
Authors: Chern Jyh‐Haur , Shia Kak‐Shan , Hsu Tsu‐An , Tai Chia‐Liang , Lee Chung‐Chi , Lee Yen‐Chun , Chang Chih‐Shiang , Tseng Sung‐Nien , Shih Shin‐Ru 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Structure‐Based Design, Synthesis, and Antimicrobial Activity of Purine Derived SAH/MTA Nucleosidase Inhibitors.
Authors: Tedder Martina E. , Nie Zhe , Margosiak Stephen , Chu Shaosong , Feher Victoria A. , Almassy Robert , Appelt Krzysztof , Yager Kraig M. 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis and Evaluation of Nonpeptide Substituted Spirobenzazepines as Potent Vasopressin Antagonists.
Authors: Xiang Min Amy , Chen Robert H. , Demarest Keith T. , Gunnet Joseph , Look Richard , Hageman William , Murray William V. , Combs Donald W. , Rybczynski Philip J. , Patel Mona 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Approaches to Intramolecular Sialylation. Part 3. Synthesis of 2,4‐Dimethoxybenzyl Ester of per‐O‐Acetylated N‐Acetylneuraminic Acid Thioglucoside and Its Attempted Oxidation with DDQ in the Presence of Nucleophiles.
Authors: Kononov L. O. , Malysheva N. N. , Ito Y. , Ogawa T. 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Total Synthesis of TMC‐95A and ‐B via a New Reaction Leading to Z‐Enamides. Some Preliminary Findings as to SAR.
Authors: Lin Songnian , Yang Zhi‐Qiang , Kwok Benjamin H. B. , Koldobskiy Michael , Crews Craig M. , Danishefsky Samuel J. 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Synthesis of New Halo‐Containing Acetylenes and Their Application to the Synthesis of Azoles.
Authors: Martins Marcos A. P. , Emmerich Daniel J. , Pereira Claudio M. P. , Cunico Wilson , Rossato Marcelo , Zanatta Nilo , Bonacorso Helio G. 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Potent and Selective, Sulfamide‐Based Human β3‐Adrenergic Receptor Agonists.
Authors: Dow Robert L. , Paight Ernest S. , Schneider Steven R. , Hadcock John R. , Hargrove Diane M. , Martin Kelly A. , Maurer Tristan S. , Nardone Nancy A. , Tess David A. , DaSilva‐Jardine Paul 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Unprecedented Copper‐Catalyzed Asymmetric Conjugate Addition of Organometallic Reagents to α,β‐Unsaturated Lactams.
Authors: Pineschi Mauro , Del Moro Frederica , Gini Francesca , Minnaard Adriaan J. , Feringa Ben L. 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
1,4,8‐Trimethylfuro[2,3‐H]quinolin‐2(1H)‐one, a New Furocoumarin Bioisoster.
Authors: Marzano Cristina , Chilin Adriana , Baccichetti Francarosa , Bettio Frazia , Guiotto Adriano , Miolo Giorgia , Bordin Franco 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Potential Hypotensive Agents: Synthesis and Hypotensive Activity of Oxime Ethers Derived from 1‐Naphthoxepines and Related Compounds.
Authors: Tandon Vishnu K. , Kumar Manoj , Awasthi Anoop K. , Saxena Hari O. , Goswamy Gajendra K. 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Xyloccensins O (Ia) and P (Ib), Unique 8,9,30‐Phragmalin ortho Esters from Xylocarpus granatum.
Authors: Wu Jun , Xiao Qiang , Huang Jianshe , Xiao Zhihui , Qi Shuhua , Li Qingxin , Zhang Si 
Published: September 2004

AbstractFor Abstract see ChemInform Abstract in Full Text.
Development of a chemoresistant orthotopic human nonsmall cell lung carcinoma model in nude mice
Authors: Mathieu Anne , Remmelink Myriam , D'Haene Nicky , Penant Stanislas , Gaussin Jean‐François , Van Ginckel Rob , Darro Francis , Kiss Robert , Salmon Isabelle 
Published: September 2004

AbstractBACKGROUNDNonsmall cell lung carcinomas (NSCLCs) are associated with very dismal prognoses, and adjuvant chemotherapy, including irinotecan, taxanes, platin, and vinca alkaloid derivatives, offer patients only slight clinical benefits. Part of the chemoresistance of NSCLC results from the expression in NSCLC cells of a very large set of endogenous proteins, which antagonize chemotherapy‐mediated attacks on these tumor cells.METHODSThe authors set up an orthotopic model of a human NSCLC by grafting A549 cells into the lungs of nude mice. They tried treating these A549 NSCLC orthotopic xenograft–bearing nude mice on the basis of various chemotherapeutic protocols, including chronic administrations of taxol, oxaliplatin, and irinotecan. A cyclooxygenase‐2 (COX‐2) inhibitor (NS‐398) also was assayed in combination with taxol. The immunohistochemical expression levels of COX‐2, prostaglandin E synthetase (PGES), ornithine decarboxylase (ODC), the lung‐related resistance protein (LRP), and glutathione‐S‐transferase‐α (GST‐α), GST‐μ, and GST‐π were quantitatively determined by means of computer‐assisted microscopy in control and drug‐treated NSCLC orthotopic xenografts.RESULTSThe orthotopic A549 xenograft model developed in 100% of the grafted mice, leading to brain metastases in approximately 61% mice and to liver metastases in approximately 40% of mice. The model was resistant to taxol and oxaliplatin and was only weakly sensitive to irinotecan. High levels of chemoresistant markers (i.e., COX‐2, PGES, ODC, LRP, GST‐α, GST‐μ, and GST‐π) were observed in the nontreated A549 xenografts, although with dramatic variations in individual expression. Taxol and oxaliplatin significantly increased the levels of expression of COX‐2, PGES, GST‐μ, and GST‐π in a number of different experimental protocols.CONCLUSIONSThe A549 orthotopic xenograft model could be used to evaluate investigational chemotherapeutic agents to identify drugs rapidly that are more active than the drugs currently in use in hospitals. Cancer 2004. © 2004 American Cancer Society.