bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly efficient baculovirus‐mediated gene transfer into rat chondrocytes
Authors: Ho Yi‐Chen , Chen Huang‐Chi , Wang Kuei‐Chun , Hu Yu‐Chen
Published: October 2004

To explore the potential of baculovirus serving as a gene delivery vector in tissue engineering of articular cartilage, the efficiencies of baculovirus‐mediated gene delivery into primary rat chondrocytes were evaluated and the transduction protocol commonly employed by others (using concentrated virus at multiplicity of infection [MOI] 200 for 1 h) was found to be ineffective (<1%). Therefore, a modified protocol was adopted, which markedly enhanced the efficiency (68%). Optimization of the transduction parameters, such as incubation time (8 h), temperature (25°C), and surrounding solutions (PBS), further increased the efficiency to 88% and prolonged the duration of expression to 21 days, suggesting that the cells previously considered nonpermissive to baculovirus transduction may be reexamined for their permissiveness using alternative transduction protocols. The elevated efficiency correlated well with increased virus uptake upon extended incubation time, as demonstrated by quantitative real‐time polymerase chain reaction (Q‐PCR). The Q‐PCR also revealed the degradation of viral DNA over culture time. Although the virus transduction somewhat hindered the cell proliferation, growth rate could be restored in the long‐term culture. More importantly, transduced cells could secrete articular cartilage‐specific type II collagen and glycosaminoglycan as well as mock‐transduced cells, confirming that normal differentiation state of rat chondrocytes is retained upon baculovirus transduction. Taken together, these data indicate that baculovirus is a safe and highly efficient gene delivery vehicle into rat chondrocytes. © 2004 Wiley Periodicals, Inc.
Glucose metabolism in the antibiotic producing actinomycete Nonomuraea sp. ATCC 39727
Authors: Gunnarsson Nina , Bruheim Per , Nielsen Jens
Published: October 2004

The actinomycete Nonomuraea sp. ATCC 39727, producer of the glycopeptide A40926 that is used as precursor for the novel antibiotic dalbavancin, has an unusual carbon metabolism. Glucose is primarily metabolized via the Entner–Doudoroff (ED) pathway, although the energetically more favorable Embden–Meyerhof–Parnas (EMP) pathway is present in this organism. Moreover, Nonomuraea utilizes a PPi‐dependent phosphofructokinase, an enzyme that has been connected with anaerobic metabolism in eukaryotes and higher plants, but recently has been recognized in several actinomycetes. In order to study its primary carbon metabolism in further detail, Nonomuraea was cultivated with [1‐13C] glucose as the only carbon source and the 13C‐labeling patterns of proteinogenic amino acids were determined by GC‐MS analysis. Through this method, the fluxes in the central carbon metabolism during balanced growth were estimated. Moreover, a shift in the label incorporation pattern was observed in connection with phosphate limitation and increased antibiotic productivity in Nonomuraea. The shift indicated an increased flux through the EMP pathway at the expense of the flux through the ED pathway, a suggestion that was supported by alterations in intracellular metabolite levels during phosphate limitation. In contrast, expression levels of genes encoding enzymes in the ED and EMP pathways were not affected by phosphate limitation. © 2004 Wiley Periodicals, Inc.
Interaction of surface‐active drugs in rabbits
Authors: Rukhadze Marina D. , Alexishvili Maka M. , Gonashvili Maia V. , Sebiskveradze Maya V.
Published: October 2004

The interaction of chlorpromazine and promethazine in vivo has been investigated. The drugs were administered to the rabbit orally as a single dose (100 mg of each drug) as well as simultaneously with an interval of 15 min. The presence of multiple peaks at the separate administration of promethazine and chlorpromazine on the one hand, and increase of number of peaks, symbathic character of kinetic curves of mentioned drugs and its prolonged appearance in the systemic circulation of the blood by simultaneous administration on the other hand, may be explained by the intensive presystem metabolism and surface‐activity ability of these drugs, and by the periodic ‘lassitude’ of liver for their capture and elimination (either presystem or systemic). The micelle formation from these drugs in the gastro‐intestinal tract and formation of the mixed micelles on simultaneous administration were also taken into consideration. Chlorpromazine is more strongly captured by the liver at its ﬁrst pass through it than promethazine, from comparison of pharmacokinetics of these drugs administered separately. Therefore, chlorpromazine on simultaneous administration occupies the sites of the liver which were covered by promethazine at single dose, thereby substituting promethazine and promoting its transferral into the systemic blood circulation. This results in a large increase in promethazine content in blood, additional peaks appear and the presence of promethazine in the blood is prolonged. The inﬂuence of chlorpromazine on the kinetics of promethazine is especially obvious when chlorpromazine enters the organism ﬁrst and more easily occupies those sites in the liver which participate in the capture and elimination of both drugs. Concerning inﬂuence of promethazine on the kinetics of chlorpromazine, promethazine reinforces in some way the ability of liver to capture chlorpromazine, thereby intensifying the presystem metabolism of chlorpromazine and inhibiting its own metabolism. The analogous effect was observed in the study of the inﬂuence of promethazine on the kinetics of carbamazepine. Copyright © 2004 John Wiley & Sons, Ltd.
CFD Simulation of Liquid Film Flow on Inclined Plates
Authors: Gu F. , Liu C.J. , Yuan X.G. , Yu G.C.
Published: October 2004

A two‐phase flow CFD model using the volume of fluid (VOF) method is presented for predicting the hydrodynamics of falling film flow on inclined plates, corresponding to the surface texture of structured packing. Using the proposed CFD model the influence of the solid surface microstructure, liquid properties and gas flow rate on the flow behavior was investigated. From the simulated results it was shown that under the condition of no gas flow the liquid flow patterns are dependent on the microstructure of the plates, and proper microstructuring of the solid surface will improve the formation of a continuous liquid film. It was also found that liquid properties, especially surface tension, play an important role in determining the thin‐film pattern. However, there are very different liquid film patterns under the action of gas flow. Thinner liquid films break easily, but thicker liquid films can remain continuous even at higher gas flow rates, which demonstrates that all factors affecting the liquid film thickness will affect the liquid film patterns under conditions of counter‐current two‐phase flow.
Adsorption Equilibrium and Adsorption Kinetics: A Unified Approach
Authors: Islam Md.A. , Khan Md.M.R. , Mozumder Md.S.I.
Published: October 2004

Conventional methods for the characterization of adsorption systems (determination of equilibrium and kinetic parameters) have been discussed. It is shown that the kinetic parameters determined by conventional methods are completely inconsistent with the equilibrium parameters. This inconsistency is due to the application of completely different models for equilibrium and kinetic study. In the present study adsorption is viewed as a Langmuir type physico‐chemical reversible process and a three‐parameter model is proposed which describes an adsorption system from both equilibrium and kinetic viewpoints. The model satisfactorily describes the kinetic and the equilibrium data reported by previous authors.
The Use of the VOF‐Model to Study the Wetting of Solid Surfaces
Authors: Ataki A. , Bart H.‐J.
Published: October 2004

The laminar liquid rivulet flow on an inclined flat metal plate and wavy metal plate is taken as a test case to validate the CFD‐simulation results using the VOF (Volume of Fluid) multiphase flow model. The local rivulet thickness was measured using an optically assisted mechanical sensor and compared with the simulation results. The circular shape of the rivulet profile has been proven for an inclined plate. Glycerin water mixtures with different concentrations were used in the experiments. Two theoretical models to describe this laminar rivulet flow in comparison to the experimental and CFD results are discussed.
The Influence of Particle Collective Characteristics on Cake Filtration Results
Authors: Anlauf H. , Sorrentino J.A.
Published: October 2004

By comprehensive investigation of varied particle size distributions and different materials, it could be demonstrated that cake properties can be successfully correlated with particle collective characteristics. Once the correlations are established, predictions of the filter performance under conditions of changing particle size are possible using existing kinetic models. It is therefore possible to reduce the total amount of work needed to get extensive information about the filtration behavior of slurries in the case of changing particle size.
Comparison of Sedimentation Behavior and Structure Analysis with Regard to Destabilization Processes in Suspensions
Authors: Beiser M. , Bickert G. , Scharfer P.
Published: October 2004

In previous publications, the sedimentation behavior of different polydisperse solids in stabilized and destabilized suspensions was investigated, however, without evaluating the effect of physicochemical suspension properties. The present study focuses on the influence of electrolyte concentration on the sedimentation behavior of quartz suspensions. Investigations were performed with a manometric sedimentation centrifuge, and a laser reflectance measuring instrument.
Influencing Sludge Compression in Solid‐Bowl Centrifuges
Authors: Erk A. , Luda B.
Published: October 2004

In order to obtain good separation results, a high sedimentation velocity of the suspended solids and fast compression kinetics of the developing sediment are necessary. The influence of different additives and treatments on the compression characteristics of inorganic, partly organic, and organic sludges (unflocculated and flocculated) in the centrifugal field is investigated.
Particle Destruction Effects in Pusher Centrifuges during Solids‐Liquid Separation
Authors: Bentz M. , Hartmetz O. , Stahl W.
Published: October 2004

Limited information is available on the mechanisms that govern undesirable particle damage or particle destruction in products during mechanical solids‐liquid separation in pusher centrifuges. To optimize the centrifuge process and to obtain a high‐quality product, it is required that the main sources of particle damage occurring during solids‐liquid separation be localized and quantified. The determination and quantification of particle destruction in a modified lab‐scale pusher centrifuge was investigated.
Washing Processes for Disperse Particulate Systems – Process Spectrum and Aspects for the Process Choice
Authors: Hoffner B. , Fuchs B. , Heuser J.
Published: October 2004

Washing of disperse solid systems is a widely used and complex operation. Since the washing step is mostly integrated into other process operations, it is subject to numerous demands exceeding by far the primary demands, like a good separation result and a low specific wash liquid demand. Because of the phenomenology and limits of different washing processes it is difficult to choose an appropriate washing process. Additionally, the acting transport mechanisms of some washing processes are not yet sufficiently understood. This work gives a broad overview of the existing washing processes, the numerous parameters, and the demands they have to meet. Based on a categorization of washing processes and the classification of these processes according to their macroscopic transport phenomena, an evaluation scheme has been developed which compares and assesses existing washing processes and shows their individual limits. The present work can be used as a rough guideline for the choice of an appropriate washing process.
Multiple Binding Modes of the Camptothecin Family to DNA Oligomers
Authors: Bocian Wojciech , Kawȩcki Robert , Bednarek Elzbieta , Sitkowski Jerzy , Pietrzyk Agnieszka , Williamson Michael P. , Hansen Poul Erik , Kozerski Lech
Published: October 2004

The binding constants of camptothecin, topotecan and its lactone ring‐opened carboxylate derivative to DNA octamers were measured by UV and NMR spectroscopy. The self‐association of topotecan (TPT) was also measured. The carboxylate form of TPT binds in the same way as the lactone, but more weakly. Titration of TPT into d(GCGATCGC)2 shows a preferred location stacked onto the terminal G1 base. However, the intermolecular NOEs cannot be reconciled with a single conformation of the complex, and suggest a model of a limited number of conformations in fast exchange. MD calculations on four pairs of starting structures with TPT stacked onto the G1–C8 base pair in different orientations were therefore performed. The use of selected experimental “docking” restraints yielded ten MD trajectories covering a wide conformational space. From a combination of calculated free energies, NOEs and chemical shifts, some of the structures produced could be eliminated, and it is concluded that the data are consistent with two major families of conformations in fast exchange. One of these is the conformation found in a crystal of a TPT/DNA/topoisomerase I ternary complex [Proc. Natl. Acad. Sci. USA 2002, 99, 15 387–15 392].
RNA Is More UV Resistant than DNA: The Formation of UV‐Induced DNA Lesions is Strongly Sequence and Conformation Dependent
Authors: Kundu Lal Mohan , Linne Uwe , Marahiel Mohamed , Carell Thomas
Published: October 2004

DNA and RNA hairpins, which represent well‐folded oligonucleotide structures, were irradiated and the amount of damaged hairpins was directly quantified by using ion‐exchange HPLC. The types of photoproducts formed in the hairpins were determined by ESI‐HPLC‐MS/MS experiments. Irradiation of hairpins with systematically varied sequences and conformations (A versus B) revealed remarkable differences regarding the amount of photolesions formed. UV‐damage formation is, therefore, a strongly sequence and conformation dependent process.
Lanthanide(III) Complexes of DOTA–Glycoconjugates: A Potential New Class of Lectin‐Mediated Medical Imaging Agents
Authors: André João P. , Geraldes Carlos F. G. C. , Martins José A. , Merbach André E. , Prata Maria I. M. , Santos Ana C. , de Lima João J. P. , Tóth Éva
Published: October 2004

The synthesis and characterization of a new class of DOTA (1,4,7,10‐tetrakis(carboxymethyl)‐1,4,7,10‐tetraazacyclododecane) monoamide‐linked glycoconjugates (glucose, lactose and galactose) of different valencies (mono, di and tetra) and their SmIII, EuIII and GdIII complexes are reported. The 1H NMR spectrum of EuIII–DOTALac2 shows the predominance of a single structural isomer of square antiprismatic geometry of the DOTA chelating moiety and fast rotation about the amide bond connected to the targeting glycodendrimer. The in vitro relaxivity of the GdIII–glycoconjugates was studied by 1H nuclear magnetic relaxation dispersion (NMRD), yielding parameters close to those reported for other DOTA monoamides. The known recognition of sugars by lectins makes these glycoconjugates good candidates for medical imaging agents (MRI and gamma scintigraphy).
Regioselectivity in Iron‐Catalyzed [2+2+1] Cycloadditions: A DFT Investigation of Substituent Effects in 1,4‐Diazabutadienes
Authors: Imhof Wolfgang , Anders Ernst
Published: October 2004

The transition‐metal‐catalyzed [2+2+1] cycloaddition reaction of 1,4‐diazabutadienes, in which the imine‐carbon atoms are part of an oxazine ring system, with ethylene and carbon monoxide leads to the regioselective formation of pyrrolidinone derivatives. To explain this regioselectivity, the transition states and intermediates of the rate‐determining step of the catalysis are determined by high‐level DFT calculations. The experimentally observed regioselectivity is consistent with the lower activation energy of the addition of ethylene towards the carbon atom next to the oxazine oxygen atom. Furthermore, the activation barrier of a conceivable back reaction is higher for the intermediates with the experimentally observed regioselectivity. These thermodynamic and kinetic arguments at first sight appear to be confirmed by the calculated NPA charges in the transition states, which reveal that the differences in these charges are greatest for those transition states that lead to the formation of the energetically favored transition structures. Nevertheless, calculations of analogous transition structures and reaction products starting from 1,4‐diazabutadienes with a 2‐fluoro, 2‐hydroxo or 2‐amino substituent revealed that the regioselectivity is not determined by the electronegativity of the heteroatom and thus by the differences in the NPA charges or the resulting Coulombic interactions in the transition structures. The main reason for the observed regioselectivities is the π‐donor ability of the substituent to contribute to a delocalized π system incorporating the adjacent imine moiety. The increasing π‐donor capability results in decreased reactivity of this moiety and increases the (relative) reactivity of the second imine group. This effect can even overcompensate for strong intramolecular Coulombic attractions in the transition structures.
An Insight into a Novel Class of Self‐Assembled Porphyrins: Geometric Structure, Electronic Structure, One‐ and Two‐Photon Absorption Properties
Authors: Zhou Xin , Ren Ai‐Min , Feng Ji‐Kang
Published: October 2004

We have theoretically investigated a series of butadiyne‐linked porphyrin derivatives that exhibit large two‐photon absorption (TPA) cross sections in the visible‐IR range. The electronic structure, one‐photon absorption (OPA), and TPA properties have been studied in detail. We found that the introduction of a butadiyne linkage and the increase of the molecular dimensionality from monomer to dimer determine the OPA intensities of Q band and Soret band, respectively. A most important role for the enhancement of the TPA cross section is played by introducing a butadiyne bridge. The complementary coordination and the combination of the terminal free base and the core zinc porphyrin are also two effective factors for the enhancement of the TPA efficiency. The dimer with two porphyrins linked at meso‐positions by a butadiyne linkage results in a maximum TPA cross section (79.35×10−48 cm4 s per photon). Our theoretical findings are consistent with the recent experimental observations. This series of porphyrin derivatives as promising TPA materials are the subject of further investigation.
Novel Metathesis Catalysts Based on Ruthenium 1,3‐Dimesityl‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidenes: Synthesis, Structure, Immobilization, and Catalytic Activity
Authors: Yang Liangru , Mayr Monika , Wurst Klaus , Buchmeiser Michael R.
Published: October 2004

The synthesis of novel ruthenium‐based metathesis catalysts containing the saturated 1,3‐bis(2,4,6‐trimethylphenyl)‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidene ligand, that is, [RuCl2(NHC){CH‐2‐(2‐PrO)‐5‐NO2‐C6H3}] (1) and [Ru(CF3COO)2(NHC){CH‐2‐(2‐PrO)‐5‐NO2‐C6H3}] (2) (NHC=1,3‐bis(2,4,6‐trimethylphenyl)‐3,4,5,6‐tetrahydropyrimidin‐2‐ylidene) is described. Both catalysts are highly active in ring‐closing metathesis (RCM) and ring‐opening cross‐metathesis (ROCM). Compound 1 shows moderate activity in enyne metathesis. Compound 2 is not applicable to enyne metathesis since it shows high activity in the cyclopolymerization of diethyl dipropargylmalonate (DEDPM). Poly(DEDPM) prepared by the action of 2 consists of 95 % five‐membered rings, that is, poly(cyclopent‐1‐enevinylene)s, and 5 % of six‐membered rings, that is, poly(cyclohex‐1‐ene‐3‐methylidene)s. The polymerization proceeds in a nonliving manner and results in polyenes with broad polydispersities (1.9≦PDI≦2.3). Supported analogues of 2 were prepared by immobilization on hydroxymethyl‐Merrifield resin and a monolithic support derived from ring‐opening‐metathesis polymerization (ROMP). Catalyst loadings of 1 and 2.5 %, respectively, were obtained. Both supported versions of 2 showed excellent reactivity. With 0.24–2 % of the supported catalysts, yields in RCM and ROCM were in the range of 76–100 %. Leaching of ruthenium was low and resulted in Ru contaminations of the products of less than 0.000014 % (0.14 ppm).
Gaseous H5P2O8− Ions: A Theoretical and Experimental Study on the Hydrolysis and Synthesis of Diphosphate Ion
Authors: Pepi Federico , Ricci Andreina , Rosi Marzio , Di Stefano Marco
Published: October 2004

The structure and reactivity of gaseous H5P2O8− ions obtained from the chemical ionization (CI) of an H4P2O7/H2O mixture and from electrospray ionization (ESI) of CH3CN/H2O/H4P2O7 solutions were investigated by Fourier transform ion cyclotron (FTICR) and triple quadrupole mass spectrometry. Theoretical calculations performed at the B3LYP/6‐31+G* level of theory and collisionally activated dissociation (CAD) mass spectrometric results allowed the ionic population obtained in the CI conditions to be structurally characterized as a mixture of gaseous [H3P2O7⋅⋅⋅H2O]−, [H3PO4⋅⋅⋅H2PO4]−, and [PO3⋅⋅⋅H3PO4⋅⋅⋅H2O]− clusters. The energy profile emerging from theoretical calculations affords insight into the mechanism of diphosphate ion hydrolysis and synthesis.
Hydrogen Bonding of Water Confined in Mesoporous Silica MCM‐41 and SBA‐15 Studied by 1H Solid‐State NMR
Authors: Grünberg Bob , Emmler Thomas , Gedat Egbert , Shenderovich Ilja , Findenegg Gerhard H. , Limbach Hans‐Heinrich , Buntkowsky Gerd
Published: October 2004

The adsorption of water in two mesoporous silica materials with cylindrical pores of uniform diameter, MCM‐41 and SBA‐15, was studied by 1H MAS (MAS=magic angle spinning) and static solid‐state NMR spectroscopy. All observed hydrogen atoms are either surface SiOH groups or hydrogen‐bonded water molecules. Unlike MCM‐41, some strongly bound water molecules exist at the inner surfaces of SBA‐15 that are assigned to surface defects. At higher filling levels, a further difference between MCM‐41 and SBA‐15 is observed. Water molecules in MCM‐41 exhibit a bimodal line distribution of chemical shifts, with one peak at the position of inner‐bulk water, and the second peak at the position of water molecules in fast exchange with surface SiOH groups. In SBA‐15, a single line is observed that shifts continuously as the pore filling is increased. This result is attributed to a different pore‐filling mechanism for the two silica materials. In MCM‐41, due to its small pore diameter (3.3 nm), pore filling by pore condensation (axial‐pore‐filling mode) occurs at a low relative pressure, corresponding roughly to a single adsorbed monolayer. For SBA‐15, owing to its larger pore diameter (8 nm), a gradual increase in the thickness of the adsorbed layer (radial‐pore‐filling mode) prevails until pore condensation takes place at a higher level of pore filling.
The Control of the Cholesteric Pitch by Some Azo Photochemical Chiral Switches
Authors: Pieraccini Silvia , Gottarelli Giovanni , Labruto Riccardo , Masiero Stefano , Pandoli Omar , Spada Gian Piero
Published: October 2004

A few chiral azo compounds, which undergo reversible photochemical switching, are presented. Of these, the most interesting contain the binaphthyl moiety and belong to the C2 (derivatives 1 and 2) or C1 symmetry group (derivatives 3 and 4). These binaphthyl compounds display intense CD and high β values. Photochemical switching has profound effects on both the CD and β values of these compounds; in the case of compound 3, the sign of β changes upon isomerisation. Compound 2 has, to our knowledge, the highest β of the switches reported in the literature and also seems the most interesting owing to its fast response to photochemical stimuli. Nematic phases can be transformed into cholesteric phases with reflection bands in the visible region by doping with reasonable amounts of 1 and 2. The reflection colours can be changed reversibly by photoisomerisation of the switches. Thermal reversion of the colourless UV photostationary state to the green isomeric EE state or to intermediate coloured states is temperature dependent. This can allow the thermal history of a sample to be traced.
2,5‐Diphenyl‐3,4‐bis(2‐pyridyl)cyclopenta‐2,4‐dien‐1‐one as a Redox‐Active Chelating Ligand
Authors: Siemeling Ulrich , Scheppelmann Imke , Heinze Jürgen , Neumann Beate , Stammler Anja , Stammler Hans‐Georg
Published: October 2004

2,5‐Diphenyl‐3,4‐bis(2‐pyridyl)cyclopenta‐2,4‐dien‐1‐one (1), a close relative of tetraphenylcyclopentadienone, is a new ligand platform for use in redox switches and sensors. Compound 1 acts as a molecular electrochemical sensor towards a range of divalent metal ions and exhibits favourable two‐wave behaviour. It forms chelates of the type [(1)MX2], whose stability is enhanced by five orders of magnitude upon one‐electron reduction. The bite angle of 1 is close to 90° in these complexes. The attachment of the 14‐valence‐electron Cp*Co fragment to the cyclopentadienone π system reduces the bite angle and thus modulates the binding characteristics of 1.
From Allylic Alcohols to Aldols by Using Iron Carbonyls as Catalysts: Computational Study on a Novel Tandem Isomerization–Aldolization Reaction
Authors: Branchadell Vicenç , Crévisy Christophe , Grée René
Published: October 2004

The tandem isomerization–aldolization reaction between allyl alcohol and formaldehyde mediated by [Fe(CO)3] was studied with the density functional B3LYP method. Starting from the key [(enol)Fe(CO)3] complex, several reaction paths for the reaction with formaldehyde were explored. The results show that the most favorable reaction path involves first an enol/allyl alcohol ligand‐exchange process followed by direct condensation of formaldehyde with the free enol. During this process, formation of the new CC bond takes place simultaneously with a proton transfer between the enol and the aldehyde. Therefore, the role of [Fe(CO)3] is to catalyze the allyl alcohol to enol isomerization affording the free enol, which adds to the aldehyde in a carbonyl‐ene type reaction. Similar results were obtained for the reaction between allyl alcohol and acetaldehyde.
Room‐Temperature Surface‐Erosion Route to ZnO Nanorod Arrays and Urchin‐like Assemblies
Authors: Li Zhengquan , Ding Yue , Xiong Yujie , Yang Qing , Xie Yi
Published: October 2004

A solution surface‐erosion route was successfully employed to produce one‐dimensional (1D) ZnO nanostructures. ZnO nanorod arrays and three‐dimensional urchin‐like assemblies could be selectively obtained with different manipulations. In this process, zinc foil was introduced to an organic solution system and acted both as a reactant and substrate to support the 1D nanostructures obtained. This method, without any template, apparatus, surfactants, or additional heterogenous substrates, has greatly simplified the preparation of oriented 1D ZnO nanostructures. In particular, this simple route could be carried out at room temperature over a period as short as several minutes, thus it could be conveniently transferred to industrial applications. The possible formation mechanism, erosion process, and influence factors were also investigated.
New Uses for the Burgess Reagent in Chemical Synthesis: Methods for the Facile and Stereoselective Formation of Sulfamidates, Glycosylamines, and Sulfamides
Authors: Nicolaou K. C. , Snyder Scott A. , Longbottom Deborah A. , Nalbandian Annie Z. , Huang Xianhai
Published: October 2004

Although the Burgess reagent (methoxycarbonylsulfamoyltriethylammonium hydroxide, inner salt) has found significant use in chemical synthesis as a dehydrating agent, almost no work has been directed towards its potential in other synthetic applications. As this article will detail, we have found that the Burgess reagent is remarkably effective at accomplishing a number of non‐dehydrative synthetic tasks when applied to appropriate substrates, such as the formation of sulfamidates from 1,2‐diols or epoxyalcohols, α‐ and β‐glycosylamines from carbohydrates, and cyclic sulfamides from 1,2‐aminoalcohols. Beyond delineating the power of these new reaction manifolds, we also describe the construction of a group of alternative Burgess‐type reagents that extends the scope of these new reactions even further.
Readily Prepared Metallo‐Supramolecular Triple Helicates Designed to Exhibit Spin‐Crossover Behaviour
Authors: Tuna Floriana , Lees Martin R. , Clarkson Guy J. , Hannon Michael J.
Published: October 2004

New dinuclear supramolecular cylinders have been designed to exhibit spin‐crossover behaviour, a form of molecular bistability. This has been achieved within the framework of our imine‐based approach to supramolecular architecture by switching from pyridylimine systems to imidazolimines. Spin‐crossover behaviour is achieved while retaining the simplicity and ease‐of‐synthesis of our molecular design. The imidazole groups used also introduce additional NH groups that engage in hydrogen‐bonding to anions and solvents. In the case of the iron(II) tetrafluoroborate complex this hydrogen bonding links supramolecular cylinders into an extended two‐dimensional array. Consistent with this, a sharper spin‐crossover transition is observed for this compound than for the corresponding hexafluorophosphate salt. More subtle anion effects are indicated in the perchlorate salt which gives a two‐step spin conversion, thereby displaying tristability.
Noncovalent Anchoring of Asymmetric Hydrogenation Catalysts on a New Mesoporous Aluminosilicate: Application and Solvent Effects
Authors: Simons Chrétien , Hanefeld Ulf , Arends Isabel W. C. E. , Sheldon Roger A. , Maschmeyer Thomas
Published: October 2004

A new Brønsted acidic aluminosilicate, AlTUD‐1, with ideal characteristics for catalyst immobilisation (mesoporous structure, high surface area, and high Altetrahedral/Si ratio), was used successfully for the noncovalent anchoring of two well‐established asymmetric hydrogenation catalysts: [RhI(cod){(R,R)‐MeDuPHOS}]BF4 (1) and [RhI(cod){(S,S)‐DiPAMP}]BF4 (2). The new heterogeneous catalysts, 1‐AlTUD‐1 and 2‐AlTUD‐1, prepared by a straightforward ion‐exchange procedure, were highly active and selective in the asymmetric reduction of dimethyl itaconate (3) and methyl 2‐acetamidoacrylate (4), giving enantiomeric excesses of up to >98 %. The catalysts showed similar behaviour to their homogeneous counterparts. Catalyst 2‐AlTUD‐1 could be re‐used multiple times without loss of enantioselectivity or activity. Leaching of Rh showed a significant dependence on the polarity of the solvent in which the catalysis was performed. By applying tert‐butylmethyl ether (MTBE) as solvent, the loss of Rh could be reduced to <0.1 %. The solvent also had a noteworthy effect on the enantioselectivity in the hydrogenation of 4 (an effect not seen with 3 as substrate), that is, in MeOH the ee was 92 %, in MTBE it dropped to 26 % when using 2‐AlTUD‐1 as catalyst.
Multifunctionalization of Synthetic Polymer Systems through Self‐Assembly
Authors: Gerhardt Warren , Črne Matija , Weck Marcus
Published: October 2004

A straightforward methodology towards the replacement of covalent strategies for the synthesis of multifunctional synthetic materials with a self‐assembling strategy that employs multiple noncovalent recognition units to attach multiple functional molecules to a polymeric scaffold is outlined. Design requirements, advantages, and potential applications, as well as the possibility of rapid optimization of materials during the manufacturing process as a result of the parallel character of self‐assembly, are presented. While still in its infancy, this novel methodology may overcome several shortcomings of current covalent multifunctionalization strategies and may yield highly complex materials that are extremely difficult or impossible to fabricate with current methods.
Chemoenzymatic Preparation of Optically Active trans‐Cyclohexane‐1,2‐diamine Derivatives: An Efficient Synthesis of the Analgesic U‐(−)‐50,488
Authors: González‐Sabín Javier , Gotor Vicente , Rebolledo Francisca
Published: October 2004

Stereoespecific syntheses of (±)‐trans‐N,N‐cyclohexane‐1,2‐diamines ((±)‐4 a–g) were carried out from the corresponding (±)‐trans‐N,N‐dialkylaminocyclohexanols by successive treatment with mesyl chloride and aqueous ammonia. The stereochemical outcome indicates the formation of a meso‐aziridinium ion intermediate. Kinetic resolutions of diamines (±)‐4 were efficiently accomplished in aminolysis reactions catalyzed by lipase B from Candida antarctica with ethyl acetate as the solvent and acyl donor. Acetamides and the remaining diamines, isolated as the benzyloxycarbonyl derivatives, were obtained with very high ee values (92–99 %). One of the carbamates was used as a precursor of the analgesic U‐(−)‐50,488.
Rhodium‐Catalyzed Intramolecular Hydroacylation of 5‐ and 6‐Alkynals: Convenient Synthesis of α‐Alkylidenecycloalkanones and Cycloalkenones
Authors: Takeishi Kenzo , Sugishima Koudai , Sasaki Kaori , Tanaka Ken
Published: October 2004

A novel intramolecular hydroacylation of 5‐ and 6‐alkynals leading to α‐alkylidenecycloalkanones was accomplished by using cationic a rhodium(I)/BINAP complex. For all cyclizations described, a single (E)‐olefin isomer was obtained. At elevated temperature, hydroacylation and double bond migration of 5‐ and 6‐alkynals proceeded in a one‐pot reaction to give cycloalkenones. An intramolecular hydroacylation of a 7‐alkynal was unsuccessful. This method represents an attractive new route to highly functionalized α‐alkylidenecycloalkanones and cycloalkenones.
Cover Picture: Zeolite Nanocrystals Inside Mesoporous TUD‐1: A High‐Performance Catalytic Composite (Chem. Eur. J. 20/2004)
Authors: Waller Peter , Shan Zhiping , Marchese Leonardo , Tartaglione Guiseppina , Zhou Wuzong , Jansen Jacobus C. , Maschmeyer Thomas
Published: October 2004

The cover picture shows HR‐TEM images of zeolite Beta (adapted from B. Slater, C. Richard A. Catlow, Z. Liu, T. Ohsuna, O. Terasaki, M. A. Camblor, Angew. Chem. 2002, 114, 1283; Angew. Chem. Int. Ed. 2002, 41, 1235), TUD‐1, and the composite zeolite Beta/TUD‐1. This composite possesses alkane cracking activity (also illustrated). For more details, see the paper by T. Maschmeyer, J. C. Jansen, et al. on p. 4970 ff.
Optimal shape of a grain or a fibre cross‐section in a two‐phase composite
Authors: Shenfeld Vladislav , Givoli Dan , Vigdergauz Shmuel
Published: October 2004

The shape of grains or of cross‐sections of fibres in a two‐phase elastic material has an important influence on the overall mechanical behaviour of the composite. In this paper a numerical scheme is devised for determining the optimal shape of a two‐dimensional grain or of a fibre's cross‐section. The optimization problem is first posed mathematically, using a global objective function, and then solved numerically by the finite element method and a specially designed global optimization scheme. Excellent agreement is obtained with analytical results available for extreme cases. In addition, optimal shapes are obtained under more general conditions. Copyright © 2004 John Wiley & Sons, Ltd.
Apoptosis of circulating tumor cells in prostate cancer patients
Authors: Larson Christopher J. , Moreno Jose G. , Pienta Kenneth J. , Gross Steve , Repollet Madeline , O'Hara S. Mark , Russell Thomas , Terstappen Leon W. M. M.
Published: October 2004

Background

The prescence of circulating tumor cells (CTCs) in the peripheral blood of cancer patients and their frequency has been correlated with disease status.

Methods

In this study, CTCs were characterized by flow cytometry and fluorescence microscopy after immunomagnetic enrichment from 7.5‐ml blood samples collected from patients with prostate cancer in evacuated blood‐draw tubes that contained an anticoagulant and a preservative. Events were classified as tumor cell candidates if they expressed cytokeratin, lacked CD45, and stained with the nucleic acid dye 4,6‐diamidino‐2‐phenylindole.

Results

In the blood of prostate cancer patients, only few of these events were intact cells. Other CTC events appeared as damaged cells or cell fragments by microscopy. By flow cytometry, these events stained variably with 4,6‐diamidino‐2‐phenylindole and frequently expressed the apoptosis‐induced, caspase‐cleaved cytokeratin 18. Similar patterns of cell disintegration were observed when cells of the prostate line LNCaP were exposed to paclitaxel before spiking the cells into normal blood samples.

Conclusions

The different observed stages of tumor cell degradation or apoptosis varied greatly between patients and were not found in blood of normal donors. Enumeration of CTCs and identification of CTCs undergoing apoptosis may provide relevant information to evaluate the response to therapy in cancer patients. © 2004 Wiley‐Liss, Inc.
Influence of calcium ions in the flow cytometric analysis of human CD8‐positive cells
Authors: Giroux Martin , Denis François
Published: October 2004

Background

The CD8 co‐receptor is an important marker used to identify various lymphocyte subsets. A significant decrease in CD8α staining intensity was observed in the presence of divalent cation chelators.

Methods

Peripheral blood mononuclear cells (PBMC) obtained from healthy volunteers were treated with calcium chelators, stained with different anti‐human CD8 mAbs, and analyzed by flow cytometry.

Results

Calcium chelators caused a dose‐dependent decrease in fluorescence intensity, using specific anti‐human CD8α mAbs. This phenomenon was not due to CD8 internalization and could be reversed by the addition of calcium ions. In contrast, calcium depletion increased staining intensity with one anti‐CD8β mAb.

Conclusions

Divalent cation chelators are used as cell anti‐clumping agents in MACS or FACS applications. Researchers should be aware that such treatment could lead to the almost complete loss of fluorescence with selected anti‐human CD8α mAbs. Since CD8 staining is used in conjunction with tetramer staining to identify antigen‐specific cytotoxic human T cells, the effect of calcium depletion should be taken into account in experimental design. © 2004 Wiley‐Liss, Inc.
Congestion control scheme for reliable multicast improving intrasession fairness with network support
Authors: Yamaguchi Makoto , Yamamoto Miki
Published: October 2004

In reliable multicast, the same information is transmitted to specified receiving nodes while maintaining reliability, with the information rate aligned to the receiving node with the lowest throughput by end‐to‐end control. However, the consideration of the receiving node with the lowest throughput produces the problem that other receiving nodes belonging to the same multicast group are limited to a considerably lower throughput than their own reception limits. This is a problem inherent to multicast communications, where the receiving nodes generally differ in congestion status. This fairness problem for receiving nodes is called intrasession fairness. In reliable multicast, it is impossible to realize intrasession fairness by using only end‐to‐end control. The purpose of this paper is to realize intrasession fairness by a scheme in which servers independently apply congestion control to the downlink by placing servers in the network and providing network support. The proposed scheme is evaluated by simulation. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(2): 61–70, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10125
Development of performance evaluation system for network systems by client observation
Authors: Saito Hiroki , Chusho Takeshi
Published: October 2004

As Internet technology comes into increasingly wide‐spread use, there is a need for quality control of network service performance to ensure user convenience, such as server access time and response time. Conventional performance evaluations aim at the control of devices at the network layer, but do not consider quality at the application layer. In this paper, the authors propose a method of performance evaluation in end‐point applications to evaluate the quality of service from the viewpoint of user convenience. This method makes possible performance measurement by introducing an observation layer that monitors the behavior of client applications, and by focusing on the request‐response communications between the client and server. A performance evaluation system that uses the principle of the observation layer has been implemented, and it is shown that the performance of an actual running system can be accurately measured, confirming the effectiveness of the performance evaluation system. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(2): 71–80, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20083
Consideration of time sharing output pulse pattern using instantaneous space voltage vector moderation for three‐phase voltage source soft‐switching inverter
Authors: Yoshida Masanobu , Hiraki Eiji , Nakaoka Mutsuo
Published: October 2004

In this paper, we propose a single inductor type resonant AC link snubber as a technique for introducing soft‐switching PWM technology into three‐phase voltage source inverters and explain its circuit operation. We then explain the suitability of instantaneous space voltage vector sinewave modulation compared to sinewave‐triangle wave relative modulation as the sinewave modulation technique of the soft‐switching inverter introducing this resonant AC link snubber, and propose a time sharing pulse pattern based on the operating principle of this resonant AC link snubber. Furthermore, we discuss the limits on the widths of the pulses that can be output when the time sharing pulse output method is used and the soft‐switching inverter performs sinewave modulation, and the need to correct narrow output pulse widths; describe in detail the relationship between the generation principle of the correction pulse pattern and the waveform distortion; and illustrate the simulation results when the minimum pulse width is corrected. Finally, we propose a new time sharing pulse pattern that does not need the minimum pulse width correction by using the time sharing pulse pattern feature for the resonant AC link inverter and demonstrate its effectiveness from the simulation results for this output pulse pattern. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(2): 34–40, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20144
Multiple bitrate output transcoder based on requantizer and reencoder sharing
Authors: Nagayoshi Isao , Kasai Hiroyuki , Hanamura Tsuyoshi , Tominaga Hideyoshi
Published: October 2004

This paper proposes a video transcoder that realizes efficiently the function of multirate conversion to multiple bitrates. The multirate conversion function is realized as follows. The decoder and the inverse quantizer are shared as a single processor. The requantizer and the reencoder with the same requantization step are shared among outputs. With these provisions, an architecture is proposed whereby the processing complexity in multirate conversion can be reduced. The number of requantization processing operations per macro‐block is examined theoretically, and it is shown that the conversion processing complexity can be formulated as a function of the output bitrate. Lastly, the theoretical evaluation and the evaluation experiment based on these investigations show that the sharing of the requantizer/reencoder is the scheme that reduces the increase of the processing complexity as a function of the number of outputs, and can cope with any number of outputs with two to four times the processing complexity of the single‐rate output scheme. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(2): 21–33, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20146
A study on double resonance H‐type slot antenna
Authors: Itakura Akira , Okano Yoshinobu , Abe Minoru
Published: October 2004

Mobile communication terminals such as mobile computers will enhance their usefulness by using wireless LAN (2.4 and 5.2 GHz) and Bluetooth (2.4 GHz). However, if both bands are used, separate antennas are needed because the frequencies are different. It is not advantageous to install separate antennas. In this paper, an H‐type slot antenna is proposed as a dual‐frequency antenna that can be integrated with a mobile computer without any extrusion from the computer body. By changing the parameters of the H‐type slot antenna, each resonant frequency can be varied independently so that a design can be straightforward. In a model packaged with an A4 Notebook PC, it is found that the bandwidth for VSWR ≤ 2 is about 22% in the 2.4‐GHz band and about 16% in the 5.2‐GHz band. Regarding the radiation characteristics, it is demonstrated that the average gain is about −4 dBi for conceivable antenna use angle that is practically sufficient. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(2): 11–20, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20148
Optical measurement of sound fields estimated from multiple interference images using Mach‐Zehnder interferometer
Authors: Ezure Tomohiro , Mizutani Koichi , Masuyama Hiroyuki
Published: October 2004

In this paper we discuss the acquisition of sound field information from optical interference patterns detected by a CCD camera. Although noncontact measurements of wide‐beamwidth sound fields based on diffraction techniques such as the Schlieren method yield projected images with high SN ratios, the problem is that sound field information is not projected correctly. In this work, the measurements were made using a Mach‐Zehnder interferometer. Because interference measurements measure light that has passed through a real focus generated by the sound fields, these measurements have a clear advantage over methods like the Schlieren method, in that they create no points at which there is a mismatch between the received light and the diffraction spots. By using CCDs as two‐dimensional time averaging detectors, wide‐range sound fields can be acquired at high speeds. In these experiments, we estimated the optical phase excursion caused by the sound field over an interval along the sound axis from 0 to 25 mm using an ultrasonic wave transducer 8.0 mm in diameter, operating at 1.4 MHz, with a beamwidth of 7 mm. Because there were bands along the sound axis within which our computational algorithm was unable to provide estimated values for the phase deviation, we augmented our primary data set with three other data sets obtained by shifting the phase of the reference light used to generate the interference pattern in the primary measurement by +0.20π, +0.48π, +0.94π (rad), and combining the resulting data sets to interpolate through the gaps in the primary data set, thereby realizing a continuous estimate along the whole sound axis. In this continuous estimate, the data we used to interpolate the primary data set came mostly from the interference pattern whose phase relative to the first measured pattern was in the neighborhood of π/2 rad. By averaging the four estimate results together, we were able to decrease the percentage of no‐data sectors over the entire range 2%. The estimated phase deviation was a gradually decreasing function with distance, starting with a value of about 0.7π rad. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(11): 20–27, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20067