bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular dynamics simulations of HPr under hydrostatic pressure
Authors: Canalia Muriel , Malliavin Thérèse E. 
Published: May 2004

AbstractThe histidine‐containing protein (HPr) plays an important role in the phosphotransferase system (PTS). The deformations induced on the protein structure at high hydrostatic pressure values (4, 50, 100, 150, and 200 MPa) were previously (H. Kalbitzer, A. Görler, H. Li, P. Dubovskii, A. Hengstenberg, C. Kowolik, H. Yamada, and K. Akasaka, Protein Science 2000, Vol. 9, pp. 693–703) analyzed by NMR experiments: the nonlinear variations of the amide chemical shifts at high pressure values were supposed to arise from induced shifts in the protein conformational equilibrium. Molecular dynamics (MD) simulations are here performed, to analyze the protein internal mobility at 0.1 MPa, and to relate the nonlinear variations of chemical shifts observed at high pressure, to variations in conformational equilibrium. The global features of the protein structure are only slightly modified along the pressure. Nevertheless, the values of the Voronoi residues volumes show that the residues of α‐helices are more compressed that those belonging to the β‐sheet. The α‐helices are also displaying the largest internal mobility and deformation in the simulations. The nonlinearity of the 1H chemical shifts, computed from the MD simulation snapshots, is in qualitative agreement with the nonlinearity of the experimentally observed chemical shifts. © 2004 Wiley Periodicals, Inc. Biopolymers 2004
Residence Time Distribution in Granulation Drums on the Example of Industrial Carbon Black
Authors: Katzer M. , Pirl S. , Esser S. , Kopietz J. , Rieckmann T. , Behnisch J. , Klasen C.‐J. 
Published: May 2004

AbstractThe present work describes systematic investigations into dry granulation of industrial carbon black with special regard to the residence time characteristics, using a continuously operated semitechnical bead‐forming drum. A novel experimental method and a model for the determination of residence time distribution of carbon black in the bead‐forming drum have been developed and very good agreement of model and experiment has been demonstrated.
Stability Behavior of Liquid Jets under Gravity
Authors: Nonnenmacher S. , Piesche M. 
Published: May 2004

AbstractThe influence of gravity on the stability behavior of falling liquid strands without external excitation was investigated. To this end, a mathematic‐physical model was developed for the analysis of the stability behavior of liquid strands in the range of low to higher viscosity, the main emphasis being on gravity. The characteristics of the model are discussed and, finally, the stability criterion is derived for the quantitative determination of the point of disintegration.
Hydrate Formation during Pressure Release of Wet CO2,View‐Cell Observations
Authors: Ullrich A. , Eggers R. 
Published: May 2004

AbstractThe objective of this work is the evaluation of the blocking risk of pipelines by hydrate crystals in processing steps. Two topics were investigated: (I) hydrate formation during pressure release and isochore cooling and (II) the influence of a contact surface on hydrate formation. The investigated materials were steel, glass, and polytetrafluoroethylene (PTFE). Experiments were carried out in a 87 mL view‐cell to observe hydrate formation in the bulk CO2 phase, since crystals of that size can cause the problems mentioned. The starting conditions of all experiments were within the temperature range of T = 278–285 K and the pressure range of p = 6–20 MPa. The results of the experiments suggest that the major criterion for hydrate formation during pressure release is the degree of supersaturation. Visible hydrate formation can be observed at a minimum subcooling of ΔT = 7 K. With a starting temperature of T = 285 K and a starting pressure of p = 6 MPa no hydrate formation is observed. The surface properties of the material have no direct influence on the hydrate formation process. However, during pressure release hydrate crystals detach from hydrophobic materials like PTFE, whereas they stick to hydrophilic materials like glass and steel. Thus, the adhesion between hydrate crystals and hydrophilic surfaces is stronger than between hydrate crystals and hydrophobic surfaces.
Mixing and Crystallization Kinetics in Gas‐liquid Reactive Crystallization
Authors: Chen P.‐C. , Chen C.C. , Fun M.H. , Y Liao O. , Jiang J.J. , Wang Y.S. , Chen C.S. 
Published: May 2004

AbstractA study of gas‐liquid reactive crystallization for CO2‐BaCl2‐H2O system was performed in a continuous flow crystallizer. The influences of mixing on the crystallization kinetics of barium carbonate crystals were investigated. The mixing parameters are stirrer speed, feed concentration, gas‐flow rate, pH of solution, addition rate of NaOH solution, and mean residence time. Under pH‐stat operation, the crystallization mechanism can be assessed by the addition rate of NaOH solution, which acts as an indicator for the absorption rate of carbon dioxide. Assuming a size‐independent agglomeration mechanism, the nucleation rate, growth rate and agglomeration kernel can be obtained, simultaneously, at steady state, by the method of moments. Evidence shows that feed concentration, feed rate, gas‐flow rate, and stirrer speed have a significant influence on the nucleation rates and mean particle sizes. This shows the effect of micromixing. The crystallization mechanism tends to be reaction limited when the feed concentration of barium chloride solution is higher than 5 mM, while at lower stirrer speeds and feed concentrations, the mechanism tends to be both mixing and reaction controlled. The growth rate depends on the mean supersaturation value and the pH of the solution and the mass‐transfer resistance cannot be completely eliminated in this work. For a monodispersal collision model, in the viscous sub‐range of turbulence, the agglomeration kernel can be expressed as β ∝ d3 $&#x003F5; \bar$–1/4, showing a low efficiency of collision. The result is also demonstrated by the agglomeration kernel expression. Comparison with a liquid‐liquid‐mixing reactive crystallization system is also discussed.
Studies on the Hydrodynamics of Chaotic Bubbling in a Gas‐Liquid Bubble Column with a Single Nozzle
Authors: Liu M. , Hu Z. 
Published: May 2004

AbstractIn this work, the chaotic bubbling mechanism in a gas‐liquid bubble column with a single nozzle was investigated. The signal for the analysis was the time series of pressure fluctuations measured from a pressure transducer probe placed in the bubble column close to the nozzle. In order to study the bubbling process, statistical analysis, qualitative and quantitative nonlinear analyses were carried out for the pressure fluctuations. Power spectra used as standard statistical measures provided preliminary evidence that bubbling in the middle values of gas flow rates may be chaotic in nature. Phase plots provided a qualitative means of analyzing the fine geometry structure of the attractor reconstructed from the bubbling time signal. Positive finite estimates of the Kolmogorov entropy provided a quantitative evidence of behavior consistent with chaos. Besides previous diagnostic tools, the local nonlinear short‐term prediction was also used as a supplement method. It was found that the bubbling process exhibits a deterministic chaotic behavior in a certain range of the gas flow rate. When increasing the gas flow rate, the sequence of periodic bubbling, primary and advanced chaotic bubbling, and jetting or random bubbling were successively observed. However, no clear period doubling sequence leading to chaotic behavior was observed. The sharp loss of the ability to predict the pressure signal successfully with the nonlinear prediction method provides the strongest evidence of the presence of the chaotic bubbling. The variations of the nonlinear invariants, such as the Kolmogorov entropy and the correlation dimension together with the plot of the correlation integral with the operation conditions, might be developed as potential and effective quantitative tools for flow regime identification of the bubbling process.
Simulation of an Acid‐Based Starch Converter
Authors: Iranshahi A. , Hakimelahi H.R. , Sotudeh‐Gharebagh R. , Mostoufi N. 
Published: May 2004

AbstractA mathematical model is proposed to simulate the starch converter. The converter was hydrodynamically divided into six zones and material and energy balances were established in each zone. Due to the fact that the converter is a laminar flow reactor, it was necessary to apply the equation oriented simulation approach to simulate the converter. Therefore, four partial differential equations were solved together by finite difference in each section. Thermophysical properties of the corresponding fluid were calculated by using various correlations and data from the literature. In order to predict accurate concentrations of glucose, the kinetics was determined with the aid of the data in the literature. A set of actual plant data from the industrial converter is used to validate the proposed model. The agreement between the model prediction and the experimental data is quite satisfactory and the model could be used to predict the performance of industrial converters at a wide range of operating conditions.
A New Era for Chemical Apparatus Engineering?
Authors: Weiß E. , Praus S. , Rudolph J. , Lietzmann A. , Mense T. 
Published: May 2004

AbstractThe ACHEMA conference is an impressive exhibition on chemical apparatus engineering, closely connected with the epoch‐making developments of chemical and process engineering. It is most timely to think about new opportunities of development. Large‐scale plant engineering and general plant construction has experienced considerable improvement during the past decades. The effects of these changes are particularly perceptible in the economic sector of German apparatus engineering. Economic pressures have given an additional impetus to a considerable shrinking process. Chemical apparatus engineering will have to focus on two main pillars in the near future: highly qualified standard and innovative products. The latter must be developed in close cooperation with the economic sector of chemical engineering in order to put the hardware required for new technologies and process strategies on the market. This article names fields of manifestation of the general technical progress. The thrust is directed toward an elevated level of product quality that can be achieved from the point of view of apparatus engineering. These are properties that will finally lead to higher profitability. The signs for a new start of apparatus engineering are quite favorable, and this opportunity has to be seized. The ACHEMA conference as a location of exchange of experiences and an opportunity of critical assessment could be a source of ideas for future work.
Superstructure of Eu4Cd25: A Quasicrystal Approximant
Authors: Pay Gómez Cesar , Lidin Sven 
Published: May 2004

AbstractThe quasicrystal approximant Eu4Cd25, formerly designated EuCd6, was synthesized and characterized by means of single‐crystal X‐ray diffraction. Superstructure reflections corresponding to an F‐centered cubic unit cell with a doubled cell‐parameter relative to the I‐centered cubic sub‐cell could be observed in the diffraction data. This gives the largest cubic unit cell reported to date among binary alloys. The superstructure exhibits structural features that are found in all the RE–Cd6 approximants as well as a further ordering between vacant/occupied Cd8 cubes and oriented Cd4 tetrahedra, which causes the superstructure. A reversible high‐temperature phase‐transition was observed at 782 K by means of DSC.
Rational Design of the Pore System within the Framework Aluminium Alkylenediphosphonate Series
Authors: Harvey Howard G. , Slater Ben , Attfield Martin P. 
Published: May 2004

AbstractWe report here on the solvothermal synthesis and crystal structure of the hybrid organic–inorganic framework material Al2[O3PC3H6PO3](H2O)2F2⋅H2O (orthorhombic, Pmmn, a = 12.0591(2) Å, b = 19.1647(5) Å, c = 4.91142(7) Å, Z = 4), the second member of the Al2[O3PCnH2nPO3](H2O)2F2⋅H2O series. The structure consists of corrugated chains of corner‐sharing AlO4F2 octahedra in which alternating AlO4F2 octahedra contain two fluorine atoms in a trans or a cis configuration. The diphosphonate groups link the chains together through AlOPOAl bridges and through the propylene groups to form a three‐dimensional framework structure containing a one‐dimensional channel system. The linkage of the corrugated inorganic AlOP layers within the structure results in the formation of two types of channel that differ in size, shape and composition. The smaller channel is unoccupied; the larger channel is more elongated and contains two extra‐framework water molecules per unit cell. A computational investigation into the driving force that controls the stacking arrangement of the AlOP inorganic layers within this series of compounds reveals that the stacking is found to be controlled by thermodynamic factors, arising chiefly from the conformation of the organic linker molecule used to connect the inorganic sheets. It is found that the registration of the inorganic layers can be engineered by selecting an appropriate, simple organic spacer or linker alkyl chain, where an even number of carbon atoms in the alkyl chain directs formation of aligned, stacked, inorganic sheets (AAAAAA), and an odd number directs formation of unaligned, stacked sheets (ABABAB) and the formation of one or two channel types in the resultant structure, respectively. This combination of alkyl‐chain linkers in conjunction with corrugated inorganic layers is an effective tool to rationally design the pore system of hybrid framework materials.
Von der kovalenten Bindung zur Struktur des Wassermoleküls. Ein Beispiel für kooperatives Lernen in der Sekundarstufe I
Authors: Markic Silvija , Kienast Stephan , Eilks Ingo 
Published: May 2004

AbstractIN VERSCHIEDENEN VERÖFFENTLICHUNGEN haben wir in den letzten drei Jahren diskutiert, pragmatischer und schülerorientierter mit der Vermittlung des Teilchenkonzepts im Chemieunterricht der Sekundarstufe I umzugehen. Hierbei haben wir vorgeschlagen, schrittweise ein in sich konsistentes und auf jeder Stufe anschlussfähiges Konzept zu vermitteln, das aus einem einfachen Teilchenkonzept, einem Atom‐ und Atombaukonzept und einem Konzept von der Struktur der kovalent aufgebauten Verbindungen bestehen könnte. In diesem Beitrag wird beschrieben, wie nach der Einführung der ersten beiden Konzepte der letzte Schritt hin zum Elektronenpaarabstoßungskonzept in verschiedenen Formen des kooperativen Lernens von den Schülerinnen und Schülern erarbeitet werden kann.
Otto Ruff und Alfred Wohl. Professoren der 1904 gegründeten Königlichen Technischen Hochschule zu Danzig
Authors: Sokolowska Teresa , Piosik Romuald 
Published: May 2004

AbstractNEBEN ZAHLREICHEN berühmten Wissenschaftlern, die an der Technischen Hochschule (Abb. 1) tätig waren, sind auch die Professoren Otto Ruff und Alfred Wohl zu nennen. In diesem Beitrag wird über die wissenschaftlichen Leistungen dieser beiden berichtet.
Untersuchung des Fortbildungsverhaltens und der Fortbildungswünsche von Chemielehrerinnen und Chemielehrern
Authors: Daus Jessica , Pietzner Verena , Höner Kerstin , Scheuer Rupert , Melle Insa , Neu Christoph , Schmidt Stefanie , Bader Hans Joachim 
Published: May 2004

AbstractDIE ANALYSE DES Fortbildungsverhaltens und der Fortbildungswünsche von Chemielehrerinnen und ‐lehrern war Gegenstand einer im Jahr 2002 durchgeführten und vom Fonds der Chemischen Industrie geförderten empirischen Untersuchung der drei Chemielehrerfortbildungszentren Braunschweig, Dortmund und Frankfurt. In diesem Artikel werden die zentralen Ergebnisse der mittels Fragebögen und Interviews erhobenen Daten von über 2.000 Chemielehrerinnen und ‐ lehrern vorgestellt.
Rac‐induced increase of phosphorylation of myosin regulatory light chain in HeLa cells
Authors: Brzeska Hanna , Szczepanowska Joanna , Matsumura Fumio , Korn Edward D. 
Published: May 2004

AbstractThe pathways by which activation of the small GTP‐binding protein Rac causes cytoskeletal changes are not fully understood but are likely to involve both assembly of new actin filaments and reorganization of actin filaments driven by the actin‐dependent ATPase activity of myosin II. Here we show that expression of active RacQ61 in growing HeLa cells, in addition to inducing ruffling, substantially enhances the level of phosphorylation of serine‐19 of the myosin II regulatory light chain (MLC), which would increase actomyosin II ATPase and motor activities. Phosphorylated myosin was localized to RacQ61‐induced ruffles and stress fibers. RacQ61‐induced phosphorylation of MLC was reduced by a maximum of about 38% by an inhibitor (Tat‐PAK) of p21‐activated kinase (PAK), about 35% by an inhibitor (Y‐27632) of Rho kinase, 51% by Tat‐PAK plus Y‐27632, and 10% by an inhibitor (ML7) of myosin light chain kinase. Staurosporine, a non‐specific inhibitor of serine/threonine kinases, reduced RacQ61‐induced phosphorylation of MLC by about 58%, at the maximum concentration that did not kill cells. Since Rac activates PAK and PAK can phosphorylate MLC, these data strongly suggest that PAK is responsible for a significant fraction of RacQ61‐induced MLC phosphorylation. To our knowledge, this is the first evidence that active Rac causes phosphorylation of MLC in cells, thus implicating activation of the ATPase activity of actomyosin II as one of the ways by which Rac may induce cytoskeletal changes. Cell Motil. Cytoskeleton 58:186–199, 2004. Published 2004 Wiley‐Liss, Inc.
Use of information resources by patients with cancer and their companions
Authors: Basch Ethan M. , Thaler Howard T. , Shi Weiji , Yakren Sofia , Schrag Deborah 
Published: May 2004

AbstractBACKGROUNDUse of the Internet is common among patients with cancer and their companions. However, little is known about patterns of use of print or telephone‐based resources amidst growing Internet utilization, nor is it known whether different types of information are sought from electronic compared with print media. It is not clear as to whether patients and their companions differ in their patterns of content seeking.METHODSA survey was developed to evaluate the use of electronic and nonelectronic informational resources by patients and their companions. During a 10‐week period, this questionnaire was administered to 443 outpatients and 124 paired companions attending an urban academic cancer center.RESULTSIn this cohort, 64% of patients and 76% of companions were computer owners, with home Internet access indicated by 58% and 68%, respectively. Use of the Internet to obtain cancer‐related information was reported by 44% of patients and 60% of companions. Print resources were used by 79% of patients and 83% of companions, with telephone resources used by 22% and 23%, respectively. The majority of Internet users also read print content (85%), whereas one‐half of print users did not access data electronically (52%). Topic areas sought via print and the Internet were similar, with the exception of nutrition‐related information, which was more commonly sought in print texts. There was a high rate of concordance between patient and companion use of both electronic and nonelectronic resources.CONCLUSIONSDespite recent publicity and scrutiny focusing on the quality of Internet health care content, print products remain the most common source of information sought by patients with cancer. Future investigation should focus on the quality of print products used by patients. Cancer 2004. © 2004 American Cancer Society.
Fludarabine and mitoxantrone for patients with chronic lymphocytic leukemia
Authors: Tsimberidou Apostolia M. , Keating Michael J. , Giles Francis J. , Wierda William G. , Ferrajoli Alessandra , Lerner Susan , Beran Miloslav , Andreeff Michael , Kantarjian Hagop M. , O'Brien Susan 
Published: May 2004

AbstractBACKGROUNDThe objective of the current study was to assess the efficacy of combination therapy with fludarabine and mitoxantrone in patients with B‐cell chronic lymphocytic leukemia (CLL).METHODSEighty‐eight patients were treated with fludarabine 30 mg/m2 intravenously daily for 3 days and mitoxantrone 10 mg/m2 on Day 1 (FN). Patients were divided into four groups based on expected response to single‐agent fludarabine. These four groups included previously untreated patients, patients who previously were treated with alkylating agents, patients who were successfully treated with alkylating agents and fludarabine but who developed recurrent disease, and patients whose disease was refractory to fludarabine with or without alkylating agents.RESULTSThe overall response rate was 66%. The response rates were 83% in previously untreated patients, 87% in patients previously treated with alkylating agents, 50% in patients whose disease was not refractory to fludarabine at the start of therapy, and 25% in patients whose disease was refractory to fludarabine. The complete remission (CR) rate was 20% for previously untreated patients, which was not significantly different from the CR rate for a group of historical control patients who were treated with single‐agent fludarabine. The median follow‐up was 8 years for surviving patients. The median progression free survival was 24 months for all patients and 34 months for previously untreated patients. The median overall survival was 40 months, and the median survival of previously untreated patients was 88 months. The most common toxicities were myelosuppression and infection. Eleven patients (12.5%) developed a second malignancy after a median of 62 months.CONCLUSIONSThe FN regimen did not have a significant advantage over fludarabine alone in the treatment of patients with CLL. Cancer 2004. © 2004 American Cancer Society.
Clonality of lobular carcinoma in situ and synchronous invasive lobular carcinoma
Authors: Shelley Hwang E. , Nyante Sarah J. , Yi Chen Yunn , Moore Dan , DeVries Sandy , Korkola James E. , Esserman Laura J. , Waldman Frederic M. 
Published: May 2004

AbstractBACKGROUNDLobular carcinoma in situ (LCIS) of the breast is considered a marker for an increased risk of carcinoma in both breasts. However, the frequent association of LCIS with invasive lobular carcinoma (ILC) suggests a precursor‐product relation. The possible genomic relation between synchronous LCIS and ILC was analyzed using the technique of array‐based comparative genomic hybridization (CGH).METHODSTwenty‐four samples from the University of California–San Francisco pathology archives that contained synchronous LCIS and ILC were identified. Array CGH was performed using random primer–amplified microdissected DNA. Samples were hybridized onto bacterial artificial chromosome arrays composed of approximately 2400 clones. Patterns of alterations within synchronous LCIS and ILC were compared.RESULTSA substantial proportion of the genome was altered in samples of both LCIS and ILC. The most frequent alterations were gain of 1q and loss of 16q, both of which usually occurred as whole‐arm changes. Smaller regions of gain and loss were seen on other chromosome arms. Fourteen samples of LCIS were related more to their paired samples of ILC than to any other ILC, as demonstrated by a weighted similarity score.CONCLUSIONSLCIS and ILC are neoplastic lesions that demonstrate a range of genomic alterations. In the current study, the genetic relation between synchronous LCIS and ILC suggested clonality in a majority of the paired specimens. These data were consistent with a progression pathway from LCIS to ILC. The authors conclude that LCIS, which is known to be a marker for an environment that is permissive of neoplasia, may itself represent a precursor to invasive carcinoma. Cancer 2004. © 2004 American Cancer Society.