bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absolute Stereochemisty and Chiroptical Properties of 3,3′-Bis(methoxycarbonyl)-9,9′-bianthryl
Authors: Toyota Shinji , Shimasaki Toshiaki , Ueda Takashi , Tanifuji Naoki , Wakamatsu Kan 
Published: November 2004

Abstract
The axially chiral title compound was enantiomerically resolved by the diastereomer method via the camphorsultamamide of the corresponding dicarboxylic acid. The absolute stereochemistry of the (+)- and (−)-forms ([α]D +32 and −33) was determined by X-ray analysis of one of the diastereomers of the sultamamide to be P and M, respectively, for the helicity about the C9–C9′ bond. The observed CD and UV spectra were reasonably reproduced by the theoretical calculation based on the time-dependent density functional theory (TDDFT). The CD spectrum of the (M)-(−) form features a split curve around 270 nm assignable to the exciton coupling of the β transition and a broad p band peak around 380 nm.
Preparation of Polystyrene-Bound Dichlorotitanium Dialkoxide and Its Application as a Polymer-Supported Lewis Acid Catalyst in Organic Syntheses
Authors: Fujita Ken-ichi , Muraki Takahito , Hashimoto Shigeru , Oishi Akihiro , Taguchi Yoichi 
Published: November 2004

Abstract
Polymer-supported dichlorotitanium dialkoxide was readily prepared from polystyrene-bound α-glycol and dichlorotitanium diisopropoxide. When we employed it as an immobilized Lewis acid catalyst, several fundamental and important Lewis acid-catalyzed reactions proceeded smoothly with fair chemical yields.
The Synthesis and Phosphate Adsorptive Properties of Mg(II)–Mn(III) Layered Double Hydroxides and Their Heat-Treated Materials
Authors: Tezuka Satoko , Chitrakar Ramesh , Sakane Kohji , Sonoda Akinari , Ooi Kenta , Tomida Tahei 
Published: November 2004

Abstract
Hydrotalcite-like layered double hydroxides (LDHs) of Mg(II) and Mn(III) were prepared by a co-precipitation/air oxidation method using MgCl2 and MnCl2 as starting materials. Syntheses were studied at different precipitation temperatures and variable starting Mg/Mn ratios. MgMn-LDH were obtained at a preparation temperature below 333 K. Samples prepared at a Mg/Mn ratio of 3 showed a crystalline LDH phase having a basal spacing of 7.85 Å. The LDH prepared at lower Mg/Mn ratios had slightly less crystalline phase, with lower basal spacing. Calcination of MgMn-LDH at 573 K for 4 h in air resulted in a transformation from a layered to an amorphous phase, accompanied by a loss of interlayer water and a partial loss of carbonate ions. Chemical analysis and IR studies showed that oxidation from Mn(III) to Mn(IV) progressed during the calcinations, and that HCO3− was formed in the calcined solid. Equilibrium distribution coefficients (Kd) of different kinds of anions were measured for the uncalcined and calcined samples. The selectivity sequences were Cl− &lt; NO3− &lt; SO42− &lt; HPO42− and Cl−, NO3−, SO42− &lt;&lt; HPO42− for the uncalcined and calcined ones, respectively. The latter had specific selectivity for phosphate ions. The calcined sample showed a maximum phosphate uptake of 1.1 mmol-P/g at a pH around of 8. The pH titration study of the supernatant solution suggested that the phosphate adsorption progresses mainly through the HCO3−/HPO42− ion exchange reaction.
Managing Knowledge-Based Resource Capabilities Under Uncertainty
Authors: Carrillo Janice E. , Gaimon Cheryl 
Published: November 2004

A firm's ability to manage its knowledge-based resource capabilities has become increasingly important as a result of performance threats triggered by technology change and intense competition. At the manufacturing plant level, we focus on three repositories of knowledge that drive performance. First, the physical production or information systems represent knowledge embedded in the plant's technical systems. Second, the plant's workforce has knowledge, including diverse scientific information and skills, to effectively operate the technical systems. Third, the firm's managerial systems embody knowledge in the form of goals, reward systems, and control and coordination systems. Taken together, we consider the technical systems, workforce knowledge, and the managerial systems as the plant's knowledge-based resource capability. Two normative models are introduced offering insight on how plant performance is impacted by investments in workforce knowledge (training) or the technical systems (process change). The models explicitly recognize that the outcome of investments in knowledge-based change is uncertain due to factors including technical problems, worker resistance, and limited financial resources. Also, we recognize that workforce knowledge may be deployed to mitigate the outcome uncertainty encountered with process change. Investments in knowledge-based change cannot be fully understood in isolation of the managerial systems. In one model, the plant manager is motivated by an incentive system that rewards the realization of a threshold goal, whereas in the other model the incentive system emphasizes the realization of meeting a particular target goal. We also investigate the impact of the manager's view of uncertainty (her willingness to absorb risk), which is influenced by the managerial systems. Results show that different characterizations of the managerial systems have a profound effect on managerial behavior and plant-level performance.
Asymptotic Values of Vector Measure Games
Authors: Neyman Abraham , Smorodinsky Rann 
Published: November 2004

In honor of L. S. Shapley's eightieth birthday The asymptotic value, introduced by Kannai in 1966, is an asymptotic approach to the notion of the Shapley value for games with infinitely many players. A vector measure game is a game v where the worth v(S) of a coalition S is a function f of μ(S) where μ is a vector measure. Special classes of vector measure games are the weighted majority games and the two-house weighted majority games, where a two-house weighted majority game is a game in which a coalition is winning if and only if it is winning in two given weighted majority games. All weighted majority games have an asymptotic value. However, not all two-house weighted majority games have an asymptotic value. In this paper, we prove that the existence of infinitely many atoms with sufficient variety suffice for the existence of the asymptotic value in a general class of nonsmooth vector measure games that includes in particular two-house weighted majority games.
Effects of Processing and Storage Conditions on Amyloid β (1–42) and Tau Concentrations in Cerebrospinal Fluid: Implications for Use in Clinical Practice
Authors: Schoonenboom Niki SM , Mulder Cees , Vanderstichele Hugo , Van Elk Evert-Jan , Kok Astrid , Van Kamp Gerard J , Scheltens Philip , Blankenstein Marinus A 
Published: November 2004

Abstract
Background: Reported concentrations of amyloid β (1–42) (Aβ42) and tau in cerebrospinal fluid (CSF) differ among reports. We investigated the effects of storage temperature, repeated freeze/thaw cycles, and centrifugation on the concentrations of Aβ42 and tau in CSF.
Methods: Stability of samples stored at −80 °C was determined by use of an accelerated stability testing protocol according to the Arrhenius equation. Aβ42 and tau concentrations were measured in CSF samples stored at 4, 18, 37, and −80 °C. Relative CSF concentrations (%) of the biomarkers after one freeze/thaw cycle were compared with those after two, three, four, five, and six freeze/thaw cycles. In addition, relative Aβ42 and tau concentrations in samples not centrifuged were compared with samples centrifuged after 1, 4, 48, and 72 h.
Results: Aβ42 and tau concentrations were stable in CSF when stored for a long period at −80 °C. CSF Aβ42 decreased by 20% during the first 2 days at 4, 18, and 37 °C compared with −80 °C. CSF tau decreased after storage for 12 days at 37 °C. After three freeze/thaw cycles, CSF Aβ42 decreased 20%. CSF tau was stable during six freeze/thaw cycles. Centrifugation did not influence the biomarker concentrations.
Conclusions: Repeated freeze/thaw cycles and storage at 4, 18, and 37 °C influence the quantitative result of the Aβ42 test. Preferably, samples should be stored at −80 °C immediately after collection.
Sensitivity of Phage Lambda upon Variations of the Gibbs Free Energy
Authors: Bakk Audun , Metzler Ralf , Sneppen Kim 
Published: November 2004

AbstractWe investigate the sensitivity of production rates (activities) of the regulatory proteins CI (repressor) and Cro at the right operator (OR) of bacteriophage lambda. The DNA binding energies of CI, Cro, and RNA polymerase are perturbed to check the uncertainty of the activity, due to the experimental error, by means of a computational scattering method according to which the binding energies are simultaneously chosen at random around the literature values, with a width corresponding to the experimental error. In a grand canonical ensemble, with the randomly drawn protein‐DNA binding energies as input, we calculate the corresponding activities of the promoters PRM and PR. By repeating this procedure we obtain a mean value of the activity that roughly corresponds to wild‐type (unperturbed) activity. The standard deviation emerging from this scheme, a measure of the sensitivity due to experimental error, is significant (typically >20% relative to wild‐type activity), but still the promoter activities are sufficiently separated to make the switch feasible. We also suggest a new, compact way of presenting repressor and Cro data.
Temperature‐Dependent Solvent Polarity Effects on Adiabatic Proton Transfer Rate Constants and Kinetic Isotope Effects
Authors: Kiefer Philip M. , Hynes James T. 
Published: November 2004

AbstractTemperature‐dependent solvent polarity effects are presented for proton transfer (PT) reactions in a polar environment in the proton adiabatic regime, in which proton motion is quantum mechanical, but is not tunneling. In this adiabatic perspective, the reaction activation free energy barrier ΔG‡ is in the solvent coordinate, with contributions due to proton and hydrogen bond vibration zero point energy, and is strongly dependent on the polarity of the solvent. In particular, the consequences of the feature that solvent polarity decreases with increasing temperature is explored within this nontraditional PT picture, via a continuum dielectric solvent model. For an acid ionization PT reaction, the activation free energy barrier increases with increasing temperature due to the solvent polarity's temperature dependence (although the so‐called intrinsic barrier and reorganization energy for the thermodynamically symmetric reaction varies in the opposite direction). The resulting PT rate constant k has a reduced effective activation energy in an Arrhenius plot due to the temperature‐dependent solvent polarity effect; this differs from the activation free energy via an activation entropy effect. The Arrhenius behavior of the kinetic isotope effect kH/kD is, however, largely unchanged by the solvent polarity's temperature dependence due to a cancellation of effects between isotopes. Some further consequences of the solvent polarity's temperature dependence for adiabatic PT systems are discussed.
Laser Infrared Multiphoton Noncoherent Control of Intermolecular (Isotope) Selectivity for Polyatomic Molecules on a Practical Scale
Authors: Letokhov Vladilen S. , Ryabov Evgeny A. 
Published: November 2004

AbstractThis paper discusses methods for noncoherent laser control of molecules, based on intermolecular selectivity of their excitation and dissociation by laser radiation, describes the technology developed for laser separation of carbon isotopes, based on the IR multiphoton dissociation of Freon‐22 molecules by CO2 laser radiation, and presents the results of developing a two‐stage laser process for the production of highly enriched (⩾ 99%) carbon‐13.
Effect of Hydrogen Bonding on Barrier‐Free Proton Transfer in Anionic Complexes of Uracil with Weak Acids: (U…HCN)− versus (U…H2S)−
Authors: Harańczyk Maciej , Rak Janusz , Gutowski Maciej , Radisic Dunja , Stokes Sarah T. , Bowen Kit H. 
Published: November 2004

AbstractA photoelectron spectrum is reported for an anionic complex of uracil (U) with HCN. The effects of electron attachment to a complex of U with HA (A = CN, NC) have been studied at the density functional theory level with 6–31++G** basis sets and the B3LYP and MPW1K exchange correlation functionals. Critical anionic structures have been reexamined at the MP2/6–31++G** level. The B3LYP gas‐phase deprotonation enthalpies are equal to 14.56, 15.13, and 15.12 eV for HNC, HCN, and H2S, respectively. The experimental deprotonation enthalpies are 15.217 ± 0.009 and 15.212 ± 0.126 eV for HCN and H2S, respectively. Hence, HCN and H2S have very indeed similar deprotonation enthalpies. The photoelectron spectra of anionic complexes of uracil with HCN and H2S are, however, very different. The (UHCN)− spectrum reveals a broad feature with a maximum between 1.2–1.4 eV, whereas the main feature of the (UH2S)− spectrum has a maximum between 1.7 and 2.1 eV. We suggest that barrier‐free proton transfer (BFPT) occurs in the (UH2S)−complex, but not in (UHCN)−. Critical factors for the occurrence of BFPT have been analyzed. The difference between the (UHCN)− and (UH2S)− complexes is attributed to differences in hydrogen bonds formed by HCN and H2S with uracil.
Efficient Exciton Quenching by Hole Polarons in the Conjugated Polymer MEH‐PPV
Authors: Yu Ji , Song Nam Woong , Mcneill Jason D. , Barbara Paul F. 
Published: November 2004

AbstractRecently published near field scanning optical measurements (NSOM) on the conjugated polymer MEH‐PPV exhibited a strong dependence of the photoluminescence intensity on the applied electric fields at the NSOM tip. The observed effect is apparently due to exciton quenching by hole polarons. In the present paper, a model “single carrier” electro‐modulated‐photoluminescence device is used to further explore the exciton quenching effect of hole polarons in MEH‐PPV. Hole polarons, created by charge injection from an ITO electrode, are observed to dramatically quench the photoluminescence intensity of MEH‐PPV. The Stern‐Volmer quenching efficiency of a hole polaron in conjugated polymer thin films was measured to be 390 nm3. This value, and other data presented herein, are consistent with the published NSOM photoluminescence modulation measurements and offer further evidence that hole polarons are efficient photoluminescence quenchers in MEH‐PPV.
Physicochemical Methods for Prediction of Functional Information for Proteins
Authors: Murga Leonel F. , Wei Ying , André Pierrette , Clifton James G. , Ringe Dagmar , Jo Ondrechen Mary 
Published: November 2004

AbstractStructural genomics initiatives are determining thousands of new protein structures. Many of these structures are of unknown function, and computational methods for the rapid determination of functional information from protein structure are needed. We present details of how functional information is obtained from the structure using THEMATICS (Theoretical Microscopic Titration Curves). THEMATICS is a computational procedure that gives information about chemical reactivity, based on solution of the Poisson‐Boltzmann equations for the electrical potential function. We show how anomalies in predicted titration curves are established. We show further that when residues with anomalous predicted titration curves form a cluster in physical space, these residues tend to be very highly conserved across species and such clusters are reliable predictors of the active site. Results are given for ten enzymes; detailed results are shown for the enzymes triosephosphate isomerase (from chicken), 6‐hydroxymethyl‐7,8‐dihydropterin pyrophosphokinase (from E. coli), and papain (from papaya).
Pump‐Probe Spectroscopy of Population Wave Packets with Intense Chirped Pulses
Authors: Segal Jonathan , Huppert Dan , Fainberg Boris D. 
Published: November 2004

AbstractWe have studied the time evolution of population wave packets under intense chirped pulse excitation by resonance heterodyne optical Kerr effect spectroscopy. In general, this method enables us to obtain complementary information about population wave packets versus the absorption spectrum of an intense chirped pulse. We have generalized the “moving potentials” picture of one of the authors to a non‐Debye solvent. We analyze the effects of both the parameters of the solvent‐solute system and the electric field on the signal of the heterodyne optical Kerr effect experiment.
Submillimeter‐scale combustion
Authors: Miesse Craig M. , Masel Richard I. , Jensen Craig D. , Shannon Mark A. , Short Mark 
Published: November 2004

AbstractUntil recently, the concept of combustion within a confined space defined by a microburner was thought to be impossible. Extensive literature dating back to Davy's seminal work in 1817 has discussed how thermal and chemical quenching set a minimum size below which no flame can exist. In this report, though, it is shown that microcombustion is possible if the wall composition and structure are carefully controlled. It is suggested that there are three keys to obtaining microcombustion: (1) the walls of the microburner need to be fabricated from materials that do not quench radicals so that the gas‐phase combustion reactions can occur unimpeded; (2) the device needs to be insulated well enough that the net heat generation is sufficient to keep the reacting mixture hot enough to sustain significant combustion; and (3) the flow pattern in the burner needs to be such that the temperature is low enough not to melt the walls, yet the flame fills the entire space. Using this design strategy, devices burning methane–air and propane–air mixtures in a 750‐μm slot were designed and optimized to achieve high conversion. These results show that microcombustion is possible with consideration of microscale engineering challenges and fitting combustor design. © 2004 American Institute of Chemical Engineers AIChE J, 50: 3206–3214, 2004
Monodispersed microbubble formation using microchannel technique
Authors: Yasuno Motohiro , Sugiura Shinji , Iwamoto Satoshi , Nakajima Mitsutoshi , Shono Atsushi , Satoh Kazumi 
Published: November 2004

AbstractRecently, we proposed microchannel (MC) emulsification, a novel method for making monodispersed emulsion with a coefficient of variation (CV) less than 5%. In this study, we attempted monodispersed microbubble formation using the MC technique. Monodispersed microbubbles were formed using surfactants and proteins as dispersing agent. The average bubble size ranged from 33.6 to 51.1 μm, and CV values were below 10%. The bubble formation behavior was compared with the droplet formation behavior. The microbubble formation appears to be based on the spontaneous transformation caused by surface tension, as previously shown for liquid–liquid systems. The average bubble size was affected by viscosity, which is consistent with the results for the liquid–liquid system in previous studies. In the case of protein, the effect of surface viscoelasticity was indicated, which was not reported for the liquid–liquid system. © 2004 American Institute of Chemical Engineers AIChE J, 50: 3227–3233, 2004
Combined experimental/numerical study on the precipitation of nanoparticles
Authors: Schwarzer Hans‐Christoph , Peukert Wolfgang 
Published: November 2004

AbstractNanoparticle precipitation in a T‐mixer was investigated experimentally as well as through simulations based on the population balance equation coupled with a global mixing model using barium sulfate as the substance under investigation. A detailed predictive precipitation model is presented and the important model parameters are identified: the mixing kinetics, the interfacial energy, and the physicochemical calculation of supersaturation. Furthermore, the capability of the global mixing model was evaluated, achieving good agreement of the mean particle sizes between experimental and simulation results. Many insights into the kinetics and the relevant time scales of the competing steps such as micromixing (mixing at the molecular level), nucleation, growth, and aggregation are obtained. However, some discrepancies in the width of the particle size distributions remain that are attributed to spatial and temporal fluctuations in the flow field and, consequently, in the mixing kinetics that cannot be resolved by the applied global mixing model. © 2004 American Institute of Chemical Engineers AIChE J, 50: 3234–3247, 2004
The total median in statistical quality control
Authors: Figueiredo Fernanda , Gomes M. Ivette 
Published: November 2004

AbstractIn industry, most of the process observations are assumed to come from a normal population, but usually we merely want to control the process mean value. It is thus sensible to find control statistics, which are ‘robust’ to monitor the process mean, giving the expected rate of false alarms whenever that mean is close to the target value, although not under a normal regime. Simulation studies for a few symmetric and asymmetric distributions allow us to suggest the total median as a robust median estimator. We shall here analyse such a robustness, as well as the robustness of the total median chart comparatively to the sample mean chart, whenever we want to control the mean value of a symmetric underlying parent. Some indication is also provided on the comparative out‐of‐control behaviour of the two charts. Copyright © 2004 John Wiley & Sons, Ltd.
Periconceptional multivitamin intake during early pregnancy, genetic variation of acetyl‐N‐transferase 1 (NAT1), and risk for orofacial clefts
Authors: Lammer Edward J. , Shaw Gary M. , Iovannisci David M. , Finnell Richard H. 
Published: November 2004

AbstractBACKGROUNDPericonceptional supplementation of multivitamins that include folic acid have been shown to prevent several birth defects, including neural tube defects and orofacial clefts. We investigated whether polymorphic variants of fetal acetyl‐N‐transferase 1 (NAT1), an enzyme involved in the catabolism of folates, differentially interacted with maternal multivitamin use during early pregnancy to alter the risk of delivering an infant with an orofacial cleft malformation.METHODSUsing a large population‐based case‐control study, we genotyped 421 California infants born with an isolated cleft and 299 controls for two NAT1 polymorphisms.RESULTSCompared to the homozygous wild‐type genotypes, odds ratios for isolated cleft lip with/without cleft palate were slightly increased among infants who were homozygous for the variant alleles of NAT1 1088 and 1095. For isolated cleft palate, no similar associations with these two NAT1 variants were observed. For NAT1 1088 genotypes, we did not observe any differential risks for clefts related to maternal multivitamin intake. For NAT1 1095 genotypes, however, we found a two‐fold higher risk for isolated cleft lip with/without cleft palate among infants who were homozygous for the variant allele and whose mothers did not take multivitamins during early pregnancy.CONCLUSIONSWe found evidence suggestive of an interaction between the NAT1 1095 polymorphism and lack of maternal multivitamin use that increased risks of isolated cleft lip with/without cleft palate. Birth Defects Research (Part A), 2004. © 2004 Wiley‐Liss, Inc.
Towards gelsolin amyloid formation
Authors: Liepina Inta , Janmey Paul , Czaplewski Cezary , Liwo Adam 
Published: November 2004

AbstractAmyloid diseases result from protein misfolding and aggregation into fibrils. Some features of gelsolin amyloidogenic fragments comprised of residues 173–243 (G173–243) and residues 173–202 (G173–202) were investigated by the method of molecular dynamics (MD). The α‐helical structure of G173–243 present in the whole protein unwinds during the course of MD simulation of the fragment G173–243, suggesting that the G173–243 structure is not stable and could unfold before becoming involved in gelsolin amyloid fibril formation. Twelve fragments of G173–202 were used to build a possible β‐fibril. During the course of the simulation, G173–202 fragments formed hydrogen bonds and tended to turn by an angle of 10°–20° towards each other. © 2004 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2004