bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and dynamics of biomolecules probed by Raman spectroscopy
Authors: Schweitzer‐Stenner Reinhard 
Published: April 2005

AbstractRaman spectroscopy is still a suitable and prominent method for probing the relationship between structure, dynamics and function of biomolecules. In this context, resonance Raman spectroscopy is of particular relevance since it allows the site‐specific investigation of chromophores (aromatic amino acid residues, nucleotides, heme groups) which are directly involved in mechanisms pivotal for the function of the respective molecules. Time‐resolved spectroscopy (Raman and IR) is utilized to explore, e.g., structural changes in heme proteins upon ligand photolysis. Conventional visible Raman is still a useful tool to explore peptides and proteins and to determine the orientation of oriented nucleic acid fibres. Copyright © 2005 John Wiley & Sons, Ltd.
Raman evidence for product binding to the enzyme W137F 4‐chlorobenzoyl‐CoA dehalogenase in two conformational states
Authors: Dong Jian , Luo Lusong , Dunaway‐Mariano Debra , Carey Paul R. 
Published: April 2005

AbstractThe enzyme 4‐chlorobenzoyl‐CoA dehalogenase catalyzes the hydrolytic dehalogenation of 4‐chlorobenzoyl‐CoA (4‐CBA‐CoA) to yield 4‐hydroxybenzoyl‐CoA (4‐HBA‐CoA). Part of the catalytic mechanism involves interaction between an active site side‐chain, from Asp145, with the 4‐position of the benzoyl moiety. For the complex consisting of product 4‐HBA‐CoA in the active site the interaction between Asp145 and the 4‐OH group helps produce a major rearrangement in the benzoyl's π‐electron system with the system becoming highly polarized. This leads to a large red shift in the benzoyl λmax, from 260 to 370 nm, and radical changes in the Raman spectrum. In addition to the Asp145‐4‐OH interaction, the aspartate side‐chain is held in place by a hydrogen bond to the indole side‐chain of Trp137. We explored the consequences of removing this hydrogen bonding interaction by using protein engineering techniques to replace Trp137 by Phe, Ala or His. For 4‐HBA‐CoA binding to Trp137Phe dehalogenase there is spectroscopic evidence for two conformational populations for bound product. One species (highly polarized) has a λmax near 375 nm and intense Raman bands at 1550, 1520 and 658 cm−1, whereas the second species (moderately polarized) has a λmax near 330 nm and an intense Raman mode at 1575 cm−1. Raman data collected between 6 and 34 °C demonstrate population changes with the highly polarized species having the highest thermodynamic stability. Copyright © 2005 John Wiley & Sons, Ltd.
The effect of land management on carbon and nitrogen status in plants and soils of alpine meadows on the Tibetan plateau
Authors: Wang W. Y. , Wang Q. J. , Wang Ch. Y. , Shi H. L. , Li Y. , Wang G. 
Published: April 2005

AbstractLarge‐scale grassland rehabilitation has been carried out on the severely degraded lands of the Tibetan plateau. The grasslands created provide a useful model for evaluating the recovery of ecosystem properties. The purposes of this research were: (1) to examine the relative influence of various rehabilitation practices on carbon and nitrogen in plants and soils in early secondary succession; and (2) to evaluate the degree to which severely degraded grassland altered plant and soil properties relative to the non‐disturbed native community. The results showed: (1) The aboveground tissue C and N content in the control were 105·97 g m−2 and 3·356 g m−2, respectively. The aboveground tissue C content in the mixed seed treatment, the single seed treatment, the natural recovery treatment and the severely degraded treatment was 137 per cent, 98 per cent, 49 per cent and 38 per cent, respectively, of that in the control. The corresponding aboveground tissue N content was 109 per cent, 84 per cent, 60 per cent and 47 per cent, respectively, of that in the control. (2) Root C and N content in 0–20 cm depths of the control had an average 1606 g m−2 and 30·36 g m−2, respectively. Root C and N content in the rehabilitation treatments were in the range of 26–36 per cent and 35–53 per cent, while those in the severely degraded treatment were only 17 per cent and 26 per cent of that in the control. (3) In the control the average soil C and N content at 0–20 cm was 11 307 g m−2 and 846 g m−2, respectively. Soil C content in the uppermost 20 cm in the seeded treatments, the natural recovery treatment and the severely degraded treatment was 67 per cent, 73 per cent and 57 per cent, respectively, while soil N content in the uppermost 20 cm was 72 per cent, 82 per cent and 79 per cent, respectively, of that in the control.The severely degraded land was a major C source. Restoring the severely degraded lands to perennial vegetation was an alternative approach to sequestering C in former degraded systems. N was a limiting factor in seeding grassland. It is necessary for sustainable utilization of seeding grassland to supply extra N fertilizer to the soil or to add legume species into the seed mix. Copyright © 2005 John Wiley & Sons, Ltd.
Influence of land management on soil nutrients and microbial biomass in the central loess plateau, northwest China
Authors: Jia G.‐M. , Cao J. , Wang G. 
Published: April 2005

AbstractLoss of soil organic matter under cropping systems is often considered one of the most serious forms of agriculturally induced soil degradation. Therefore, understanding how to improve or maintain soil fertility is of importance for sustainable systems of agriculture. This study deals with the effects of succession fallow and fertilization combined with crop rotation on the chemical properties and microbial biomass of soil in the central Loess Plateau, China. In order to create a more uniform experimental environment and avoid the influence of different crop residues, wheat/potato (W/P) rotation was selected as a fertilization treatment. The results showed that with increasing fallow time organic carbon (Corg) and total nitrogen (TN) slightly increased, microbial biomass carbon (MBC) and MBC/Corg gradually decreased, and microbial biomass nitrogen (MBN) remained unchanged. However, only MBC/Corg among all the microbial parameters measured showed significant differences at various stages of fallow. Although there was a decrease in organic carbon and total nitrogen in the fertilized plots, MBC was not significantly different in the various fallow and fertilized plots except for one‐year‐old fallows, which had the highest MBC. MBN, MBC/Corg and MBN/TN in fertilized plots were higher than for plots at different stages of fallow. Fertilization can increase organic carbon, total nitrogen, MBC and MBN content (compared to the control). It was concluded that appropriate land management, such as fertilization combined with crop rotation and reducing one‐year‐old fallow, would be useful ways to improve or maintain soil fertility. Copyright © 2005 John Wiley & Sons, Ltd.
Knowing and doing: How to put learning where the work is
Authors: Bordonaro Frank P. 
Published: April 2005

AbstractThe idea that knowing and doing should be tightly linked may seem like a management no‐brainer. But progress in putting learning more directly on the path of work has been slowed by conventional thinking. How can leaders move learning to the places and people where it can most powerfully further the strategy of the company? First, they must put aside old habits and form a new perspective about where the most important learning takes place.
Modeling of Ethylene‐Norbornene Copolymer Microstructure in Solution Polymerization with Homogeneous Metallocene Catalysts
Authors: Park Seung Young , Choi Kyu Yong 
Published: April 2005

AbstractSummary: The microstructure of ethylene‐norbornene copolymer produced in solution polymerization is analyzed through kinetic modeling and experiments using homogeneous rac‐Et(1‐indenyl)2ZrCl2/methylaluminoxane catalyst in toluene at 70 °C. The sequence distribution function and average chain length equations are derived for terminal model and penultimate model. The model simulations show that both models provide similar predictions of average copolymer composition, especially at low norbornene concentration in the copolymer. However, at higher norbornene concentrations the penultimate model yields much better predictions of norbornene sequence length distribution than the terminal model. The terminal model has been inadequate in describing the copolymerization rate, whereas the penultimate model yields excellent predictions of rate behavior. The model calculations also indicate that at norbornene concentration in the copolymer larger than about 10 mol‐%, the maximum ethylene block length is smaller than 70, prohibiting the formation of crystalline copolymer.Ethylene sequence distribution curves at different mol‐% of norbornene in copolymer.magnified imageEthylene sequence distribution curves at different mol‐% of norbornene in copolymer.
Comparison of Gas and Liquid Propylene Polymerization Technique – Hydrogen Effect on Thermal, Rheological, and Morphological Properties of PP
Authors: Stern Claudia , Frick Achim Robert , Pater Joachim Theodorus Maria , Weickert Günter 
Published: April 2005

AbstractSummary: A comparison of PP qualities, which are produced with two different polymerization techniques–gas phase(GP) and liquid pool (LP)–under precise control of the polymerization temperature (70 °C) and pressure (GP = 25 bar, LP < 60 bar) using identical Ziegler‐Natta catalyst (TiCl4/phthalate/MgCl2 + TEA/silane), is presented. A series of homopolymer PP in a wide MW range from 100 000 to 1 600 000 g · mol−1 was polymerized. During polymerization all samples were characterized exactly by their Rp‐profil. The effect of hydrogen on the initial reaction rate and on MW and MWD was analyzed on the basis of this so‐called kinetic fingerprint. The results showed that the polymerization rate reached a maximum for LP, of about 150 kg · gcat−1 · h−1, in contrast to GP with a maximum of Rp,0 = 45 kg · gcat−1 · h−1. Analysis was carried out by means of GPC, SEM, DSC, platte‐platte rheometer, and WAXS. The results first showed that the MWD of LP PP is narrower (PD ∼ 6.8) than for the GP PP (PD ∼ 8), polymerized in two steps. An SEM study of the powder particle shows the typical dent surface morphology of polymers using Ziegler‐Natta catalysts for polymerization. WAXS and DSC analysis demonstrated that almost only the α‐modification of crystalline structure exists and that the crystallinity becomes considerably higher after solidification from melt. Furthermore, it was found that the crystallite size distribution depends on the polymerization technique. Rheological studies indicate that GP PP behaves more elastically. To summarize, it is shown that PP produced with the LP polymerization technique is more homogenous and of high quality.Particle geometry of gas phase and liquid pool polymerized PP powder observed by SEM (PP‐L0).magnified imageParticle geometry of gas phase and liquid pool polymerized PP powder observed by SEM (PP‐L0).
A Unified Model for the Mixing of Non‐Newtonian Fluids in the Laminar, Transition, and Turbulent Region
Authors: Wassmer Karl‐Heinz , Hungenberg Klaus‐Dieter 
Published: April 2005

AbstractSummary: Non‐Newtonian fluid behavior has significant influence on quantities in chemical engineering like power input, mixing time, heat transfer etc. In the laminar flow region, the concept of effective viscosity by Metzner and Otto is well established. In the transition region between laminar and turbulent flow, the existing concepts use three and even more empirical parameters to determine the specific power input. Here, a unified and general but simple approach is introduced to calculate the power input for shear thinning fluids over the whole flow region using just one empirical parameter. The Metzner‐Otto relation is obtained as a limiting case for the laminar region. The empirical parameter of the new approach is related to the Metzner‐Otto constant. The concept is validated for eight different stirrer systems. Mixing time and maximum shear rate and heat transfer can also be calculated using this approach. The new concept presented should also be applicable for other apparatuses, e.g., static mixers.Comparison of experimental data and a curve calculated according to the new method (solid line).magnified imageComparison of experimental data and a curve calculated according to the new method (solid line).
Identifying and distinguishing cases of parkinsonism and Parkinson's disease using ICD‐9 CM codes and pharmacy data
Authors: Swarztrauber Kari , Anau Jane , Peters Dawn 
Published: April 2005

AbstractAdministrative databases have the potential to assess quality and cost of care for parkinsonism and Parkinson's disease. However, the validity of findings is limited by our understanding of how cases are identified. Patient records listing International Classification of Diseases, Version 9, Clinical Modification (ICD‐9 CM) codes for parkinsonism (n = 2,076) and dopaminergic medications (n = 2,798) were pulled from fiscal years 1999 to 2001 for patients in the Pacific Northwest Veterans Administration. Samples of these records (n = 397) and records without these ICD‐9 CM codes (n = 500) were reviewed, and clinical data were extracted. The accuracy of administrative data to identify and distinguish between Parkinson's disease and parkinsonism was calculated. A total of 37.9% of parkinsonism cases were detected using pharmacy data and ICD‐9 CM codes compared to 18.7% by using ICD‐9 CM codes alone. The ICD‐9 CM code for paralysis agitans (332.0) did not distinguish between probable Parkinson's disease and other causes of parkinsonism, whereas the ICD‐9 CM code for degenerative basal ganglia disorder (333.0) predicted having secondary parkinsonism (odds ratio [OR] = 5.0) as well as dopa‐responsiveness in patients without secondary parkinsonism (OR = 4.5). Administrative data are limited in the ability to identify parkinsonism. The ICD‐9 CM code, 332.0, which is generally considered the code to identify Parkinson's disease, did not distinguish between parkinsonism and Parkinson's disease. © 2005 Movement Disorder Society
Association between male gender and pediatric essential tremor
Authors: Louis Elan D. , Fernandez‐Alvarez Emilio , Dure Leon S. , Frucht Steven , Ford Blair 
Published: April 2005

AbstractApproximately 5% of new essential tremor (ET) cases arise during childhood. The goal of the current report was to examine the possible association between male gender and pediatric ET, using data from 95 pediatric ET cases seen at three medical centers (two in the United States and one in Spain). The odds of ET in our sample of cases were threefold higher in boys compared to girls. Whether this association between male gender and pediatric ET represents a selection bias or a true gender‐mediated biological difference in disease expression is not known, although some data support the latter possibility. © 2005 Movement Disorder Society
Anticancer multidrug resistance mediated by MRP1: Recent advances in the discovery of reversal agents
Authors: Boumendjel Ahcène , Baubichon‐Cortay Hélène , Trompier Doriane , Perrotton Thomas , Di Pietro Attilio 
Published: April 2005

AbstractMultidrug resistance protein 1 (MRP1) belongs to the ATP‐binding cassette (ABC) transporter family. It is able to transport a broad range of anticancer drugs through cellular membranes, thus limiting their antiproliferative action. Since its discovery in 1992, MRP1 has been the most studied among MRP proteins, which now count nine members. Besides the biological work, which targets structure elucidation, binding sites location, and mode of action, most efforts have been focused on finding molecules which act as MRP1 inhibitors. In this review, we attempt to summarize and highlight studies dealing with modulators of MRP1‐mediated multidrug resistance (MDR), which have been accomplished in the last 5 years. The reported MRP1 inhibitors are discussed according to their chemical class. Finally, we try to bring information on structure–activity relationship (SAR) aspects and how modulators might interact with MRP1. This study may facilitate the rational design of future modulators of MDR. © 2005 Wiley Periodicals, Inc.
Kinetic study of the effect of poly(phenyl sulfone) on the curing of an epoxy/amine resin by conventional and by temperature‐modulated differential scanning calorimetry
Authors: Cedeño Asdrúbal J , Vázquez‐Torres Humberto 
Published: April 2005

AbstractKinetic studies of the curing reaction of semi‐interpenetrating polymer networks (semi‐IPNs) based on diglycidyl ether of bisphenol‐A (DGEBA) and 4,4′‐diaminodiphenylmethane (DDM), containing poly(phenyl sulfone) (PPSU), were carried out using differential scanning calorimetry (DSC) and temperature‐modulated DSC (TMDSC), under both isothermal and dynamic conditions. The curing kinetics is discussed in the framework of three kinetic models: the Kissinger and the Flynn–Wall–Ozawa models, and the autocatalytic model developed by Kamal. To describe the cured reaction in its latter stage, we used the semi‐empirical relationship proposed by Chern and Poehlein to consider the influence of diffusion on reaction rate. The cure mechanism for the system studied remained broadly autocatalytic regardless of PPSU content, and it became far more diffusion controlled at higher PPSU content and lower cure temperatures. The vitrification time of the resins was obtained with TMDSC by following the changes on the complex modulus of heat capacity, $|C_{\rm {P}}^{*}|$, and exhibited a strong dependence on the PPSU content in the semi‐IPN systems. Copyright © 2005 Society of Chemical Industry
Synthesis and characterization of stable blue light‐emitting poly(spirobifluorene) derivatives containing alkoxy group
Authors: Lee Ki‐Suk , Kim Yun‐Hi , Lee Yongkyun , Jang Jin , Kwon Soon‐Ki 
Published: April 2005

AbstractPolymers containing alkoxy‐substituted spirobifluorene have been prepared from nickel(0)‐mediated coupling or palladium‐catalyzed Suzuki coupling. The polymers were characterized using various spectroscopies, such as 1H‐NMR, FT‐IR, and elemental analysis. The high glass transition temperature and high decomposition temperature suggested that the resulting polymers possessed a high thermal stability. The obtained polymers possessed weight average molecular weight of 4500–33,000 with polydispersity index of 1.1–1.9 and good solubility. The low onsets of the oxidation potential suggested that the polymers containing alkoxy substituted spirobifluorene possessed a good hole injection property. The photoluminescence and electroluminescence of the polymers containing alkoxy substituted spirobifluorene showed stable blue color by suppressing the excimer formation due to intermolecular interaction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2316–2324, 2005
Density functional theory simulations of two‐dimensional infrared spectra for hydrogen‐bonded acetic acid dimers
Authors: Dreyer Jens 
Published: April 2005

AbstractTwo‐dimensional coherent infrared spectra are simulated based on density functional theory calculations to analyze vibrational couplings in hydrogen‐bonded acetic acid dimers. Anharmonic sixth‐order force fields covering up to three‐body interactions are calculated for up to 11 normal modes. Three mechanisms for vibrational coupling within the two intermolecular hydrogen bonds are considered: anharmonic coupling of the high‐frequency OH stretching mode to low‐frequency modes, Fermi resonance coupling the of OH stretching mode to fingerprint mode combination tones, and a combination of both. Predicted coherent two‐dimensional infrared spectra show distinct signatures for the different coupling mechanisms. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
A generalized stock control formulation for stock management problems involving composite delays and secondary stocks
Authors: Yasarcan Hakan , Barlas Yaman 
Published: April 2005

AbstractIt is well established in the system dynamics literature that if the stock management formulation ignores the supply line delay, the behavior of a system can be highly oscillatory. But there are no general decision rules to handle other types of delays in stock management systems, such as information delays in decision processing and delays implicit in controlling a primary stock indirectly via a secondary stock. In this research, it is first shown that the consequence of ignoring information delays or ignoring the delays implicit in secondary stock control is equivalent to ignoring the supply line delay in the standard case: large oscillations. Next, the notion of “virtual supply line” is introduced and a generalized stock control heuristic that does take into account these indirect or composite delays is derived; it is shown that the result is a stabilized dynamic behavior. Finally, the decision heuristic is implemented on an example involving all three types of delays, demonstrating the “generic” nature of the proposed formulation structure. The combined result is a significant improvement in the stability of the system, when compared with the standard formulation that considers the supply line delays only. It is also shown that the stability of the results is quite insensitive to even large errors in parameter estimates. The proposed policy is compared with some other standard stabilizing policies used in system dynamics and it is shown that the proposed policy can be conveniently combined with such policies to yield superb stability results. Finally some implementation issues and potential solutions are discussed. Copyright © 2005 John Wiley & Sons, Ltd.
Synthesis, Crystal Structure, and Vibrational Spectra of Ca4P6O19 (Trömelite) ‐ a catena‐Hexaphosphate
Authors: Höppe Henning A. 
Published: April 2005

AbstractThe catena–hexaphosphate Ca4P6O19 (Trömelite) was obtained by the reaction of calcium oxide with H3PO3 in a tube furnace at a temperature of 900 °C and crystallizes triclinic (space group $P{\bar 1}$, Z = 2, a = 685.70(9) pm, b = 915.47(12) pm, c = 1282.25(17) pm, α = 109.602(10)°, β = 99.778(10)°, γ = 91.917(10)°, V = 743.70(17)·106 pm3). According to the powder diffraction data of Ca4P6O19 a Rietveld refinement of the lattice constants was performed; this confirmed the single–crystal data. Trömelite contains chains of six condensed corner‐sharing PO4 tetrahedra with the Ca atoms in the voids of the resulting structure. IR and Raman data of Trömelite are also presented.
Synthesis and Crystal Structure of Ammine Copper(I) Cyanamide, Cu4(NCN)2NH3
Authors: Liu Xiaohui , Müller Paul , Dronskowski Richard 
Published: April 2005

AbstractAmmine copper(I) cyanamide, Cu4(NCN)2NH3, was obtained as a white powder from the reaction between CuCl and H2NCN in concentrated ammonia solution. X‐ray and neutron diffraction experiments yield the hexagonal system with space group P63mc (no. 186) and a = 5.7661(1) Å, c = 10.7817(3) Å, and Z = 2. The structure is characterized by layers of monovalent copper ions with an average Cu–Cu distance of 2.89Å, and the layers are connected through two crystallographically independent NCN2− units. While one CuI is linearly bonded to an NCN2− unit and an additional NH3 molecule, the other CuI is also linearly coordinated but by two NCN2− groups; the Cu–N bonds lie between 1.86–1.98Å. The C–N bond lengths and angles evidence both NCN2− groups as essentially linear cyanamides.