bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vivo experiments with tracheostoma tissue connector prototypes
Authors: Olivier ten Hallers E. J. , Van der Houwen Eduard B. , Marres Henri A. M. , Rakhorst Gerhard , Jansen John A. , Schutte Harm K. , Van Kooten Theo G. , Van Loon Jan‐Paul , Verkerke Gijsbertus J. 
Published: February 2007

AbstractIn cancer patients who have undergone total surgical removal of the larynx, ideally voice rehabilitation should be performed using a shunt valve (placed in a fistula of the tracheo–esophageal wall) and a tracheostoma valve (TSV) to enable hands‐free tracheo–esophageal speech. A tracheostoma is created by suturing the trachea into the lower anterior part of the neck, and a TSV is a device that can be placed at the stoma. Unfortunately, many patients are unable to use a TSV, mainly due to fixation difficulties. To improve the fixation of the TSV, tracheostoma tissue connector (TS‐TC) prototypes have been designed. Prototype 1 consisted of a titanium ring, inner diameter 30 mm, with a circular polypropylene mesh glued to it with silicone adhesive. Four holes had been drilled into the ring for the insertion of sub‐ and percutaneous screws. Prototype 2 consisted of a silicone rubber ring, inner diameter 30 mm, combined with polypropylene mesh and four titanium inserts that functioned as a base plate for the insertion of sub‐ and percutaneous screws. In adult female goats a tracheostoma was created and the prototypes were implanted. After 6 weeks of subcutaneous implantation, percutaneous screws were inserted. After twelve weeks, the experiment was terminated and the implants with the surrounding tissues were processed and examined histologically. The clinical appearance during weeks 7–12 varied from very poor to relatively good. Histologically, the implants showed a uniform inflammatory response. We found that all the tissue surrounding the screws showed signs of epithelial down growth. It was concluded that the two‐stage implantation procedure of our prototype TS‐TCs in this animal model was unsuccessful. Additional research efforts are necessary to improve tissue immobilization and to devise reliable fixation systems for TSVs. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Alginate/polyethylene glycol blend fibers and their properties for drug controlled release
Authors: Wang Qun , Zhang Na , Hu Xianwen , Yang Jianhong , Du Yumin 
Published: February 2007

AbstractFibers of alginate and polyethylene glycol (PEG), with salicylic acid (SA) as model drug incorporated in different concentrations, were obtained by spinning their solution through a viscose‐type spinneret into a coagulating bath containing aqueous CaCl2 and ethanol. Chemical, morphological, and mechanical properties characterization were carried out, as well as the studies of the factors that influence the drug releasing from alginate/PEG fibers. These factors included the component ratio of alginate and PEG, the loaded amount of SA, the pH, and the ionic strength of the release solution and others. The best values of the tensile strength at 13.41 cN/tex and breaking elongation at 23.13% of blend fibers were obtained when the PEG content was 5 wt %; the water swelling ratio (WSR) of blend fibers increased as the composition of PEG was raised. The results of controlled release tests showed that the amount of SA released increased with an increase in the proportion of PEG present in the fiber. Moreover, the release rate of drug decreased as the amount of drug loaded in the fiber increased, but the cumulative release amount is increasing. The alginate/PEG fibers were also sensitive to pH and ionic strength. For pH 7.4 the drug release was faster compared to pH 1.0, being simultaneously accelerated by a higher ionic strength. All the results indicated that the alginate/PEG fiber was potentially useful in drug delivery systems. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Branched chitosans: Effects of branching parameters on rheological and mechanical properties
Authors: Aggarwal Dinesh , Matthew Howard W.T. 
Published: February 2007

AbstractChitosan continues to be studied as a promising biomaterial for tissue repair and regeneration applications. However, chitosan structures show a large reduction in tensile strength in the wet state. Methods for improving the wet strength of chitosan materials may broaden its applicability as a tissue scaffold for applications requiring significant load bearing capacity. In this study, the role of molecular architecture in defining the mechanical properties of hydrated chitosan membranes was examined. Specifically, branched chitosan molecules were synthesized with a range of branch lengths and branch densities. Physical and mechanical properties were characterized using viscometry, FTIR spectroscopy, and tensile testing measurements, and the results were correlated with the postulated architecture of the linear and branched chitosan materials. Both branch density and branch length were found to influence the mechanical properties of chitosan membranes. For example, high‐molecular‐weight (600 kDa) chitosans grafted with 80 kDa branches exhibited up to twofold increases in both tensile strength and extensibility. FTIR results indicated that these increases correlated with enhanced levels of hydrogen bonding in the branched materials. Vascular smooth muscle cells cultured on cast membranes of the branched chitosans exhibited no differences in adhesion or spreading as compared to the linear polymer. The results indicate that the mechanical properties of chitosan materials can be improved by the induction of a branched molecular architecture. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Nanostructural characteristics, mechanical properties, and osteoblast response of spark plasma sintered hydroxyapatite
Authors: Li H. , Khor K.A. , Chow V. , Cheang P. 
Published: February 2007

AbstractThis study aimed to fabricate bulk nanostructured hydroxyapatite (HA) pellets with improved properties using spark plasma sintering (SPS) for orthopedic applications. Spray‐dried nanostructured HA (nSD‐HA) powders were consolidated using the rapid SPS processing. The SPS processed nSD‐HA was characterized using Raman spectroscopy and field emission scanning electron microscopy (FESEM). Mechanical properties of the consolidates were also evaluated through indentation approach. The nanostructures (∼80 nm in grain size) of the starting powders were successfully retained after the SPS processing operated at 950°C with <15 min holding time. The SPS consolidated nSD‐HA showed promising mechanical properties, ∼118 GPa for Young's modulus, and up to 2.22 MPa m0.5 for fracture toughness. SPS holding time showed minor influence on the phases of the pellets. Furthermore, the spheroidized nanostructured HA retained the HA structure after the SPS consolidation. Preliminary cytotoxicity and cell attachment studies were also carried out using a human osteoblast cell line hFOB 1.19. Enhanced cell attachment and proliferation on the nanostructured pellets were revealed. The presence of the nanostructures accounts mainly for the enhanced mechanical properties and promoted proliferation of the osteoblast cells. This study suggests that the SPS technique is an appropriate process for fabrication of bulk nSD‐HA from nanostructured powder. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Development of a useful technique to discriminate anterior cruciate ligament cells and mesenchymal stem cells—The application of cell electrophoresis
Authors: Lee I‐Chi , Wang Jyh‐Horng , Lee Yu‐Tsang , Young Tai‐Horng 
Published: February 2007

AbstractMesenchymal stem cells (MSCs) can differentiate into multiple nonhematopoietic cell lineages, including osteoblasts, chondrocytes, and ligament cells. The purpose of this study is to identify the difference between MSCs and anterior cruciate ligament (ACL) cells for the application of distinguishing these two cells during the process of MSCs differentiating into ACL cells. Although culture of MSCs and ACL cells have been studied extensively, it was found that these two cells could not be distinguished from their appearance, expression of surface antigens (including CD105, CD34, CD45, CD29, CD44, and CD71), α‐smooth muscle actin, and mRNAs for type I collagen, type III collagen, and tenascin‐C, based on a series of traditional methods for cell identification. Cell electrophoresis, measuring the electrophoretic mobility (EPM) of cells, was proposed to investigate the discrepancy in surface charge properties of MSCs and ACL cells. Surprisingly, the EPM value of MSCs is significantly greater than that of ACL cells (p < 0.001). Although cell electrophoresis cannot determine the specific surface protein, it can reflect the net surface charge density of cell membrane, which can be influenced by the dissociation of functional groups of peripheral membrane proteins. Therefore, it is suggested that cell electrophoresis, while simple and cheap in manipulation, can serve as a useful research tool to assist in identification of MSCs differentiating into ACL cells. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Development of parallel density functional program using distributed matrix to calculate all‐electron canonical wavefunction of large molecules
Authors: Inaba Toru , Sato Fumitoshi 
Published: February 2007

AbstractWe developed a new parallel density‐functional canonical molecular‐orbital program for large molecules based on the resolution of the identity method. In this study, all huge matrices were decomposed and saved to the distributed local memory. The routines of the analytical molecular integrals and numerical integrals of the exchange‐correlation terms were parallelized using the single program multiple data method. A conventional linear algebra matrix library, ScaLAPACK, was used for matrix operations, such as diagonalization, multiplication, and inversion. Anderson's mixing method was adopted to accelerate the self‐consistent field (SCF) convergence. Using this program, we calculated the canonical wavefunctions of a 306‐residue protein, insulin hexamer (26,790 orbitals), and a 133‐residue protein, interleukin (11,909 orbitals) by the direct‐SCF method. In regard to insulin hexamer, the total parallelization efficiency of the first SCF iteration was estimated to be 82% using 64 Itanium 2 processors connected at 3.2 GB/s (SGI Altix3700), and the calculation successfully converged at the 17‐th SCF iteration. By adopting the update method, the computational time of the first and the final SCF loops was 229 min and 156 min, respectively. The whole computational time including the calculation before the SCF loop was 2 days and 17 h. This study put the calculations of the canonical wavefunction of 30,000 orbitals to practical use. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Electron correlation: The many‐body problem at the heart of chemistry
Authors: Tew David P. , Klopper Wim , Helgaker Trygve 
Published: February 2007

AbstractThe physical interactions among electrons and nuclei, responsible for the chemistry of atoms and molecules, is well described by quantum mechanics and chemistry is therefore fully described by the solutions of the Schrödinger equation. In all but the simplest systems we must be content with approximate solutions, the principal difficulty being the treatment of the correlation between the motions of the many electrons, arising from their mutual repulsion. This article aims to provide a clear understanding of the physical concept of electron correlation and the modern methods used for its approximation. Using helium as a simple case study and beginning with an uncorrelated orbital picture of electronic motion, we first introduce Fermi correlation, arising from the symmetry requirements of the exact wave function, and then consider the Coulomb correlation arising from the mutual Coulomb repulsion between the electrons. Finally, we briefly discuss the general treatment of electron correlation in modern electronic‐structure theory, focussing on the Hartree‐Fock and coupled‐cluster methods and addressing static and dynamical Coulomb correlation. © 2007 Wiley Periodicals, Inc. J Comput Chem 28: 1307–1320, 2007
A PM3/d specific reaction parameterization for iron atom in the hydrogen abstraction catalyzed by soybean lipoxygenase‐1
Authors: Tejero Ismael , González‐Lafont Àngels , Lluch José M. 
Published: February 2007

AbstractThis paper reports a specific reaction parameter (SRP) PM3/d model for iron that can reproduce the DFT/MM results of the hydrogen abstraction reaction from the C11 position of linoleic acid by the Soybean lipoxygenase‐1 enzyme. A suite of nonlinear optimization methods is outlined for semiempirical parameter development based on integrated evolutionary (genetic) and direction set minimization algorithms. The PM3/d‐SRP Fe parameters are derived along three consecutive steps. The final parameterization step includes the effect of the whole enzyme in order to get a better quantum mechanical/molecular mechanical description. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Computational chemistry approach to protein kinase recognition using 3D stochastic van der Waals spectral moments
Authors: González‐díaz Humberto , Saíz‐urra Liane , Molina Reinaldo , González‐díaz Yenny , Sánchez‐gonzález Angeles 
Published: February 2007

AbstractThree‐dimensional (3D) protein structures now frequently lack functional annotations because of the increase in the rate at which chemical structures are solved with respect to experimental knowledge of biological activity. As a result, predicting structure‐function relationships for proteins is an active research field in computational chemistry and has implications in medicinal chemistry, biochemistry and proteomics. In previous studies stochastic spectral moments were used to predict protein stability or function (González‐Díaz, H. et al. Bioorg Med Chem 2005, 13, 323; Biopolymers 2005, 77, 296). Nevertheless, these moments take into consideration only electrostatic interactions and ignore other important factors such as van der Waals interactions. The present study introduces a new class of 3D structure molecular descriptors for folded proteins named the stochastic van der Waals spectral moments (oβk). Among many possible applications, recognition of kinases was selected due to the fact that previous computational chemistry studies in this area have not been reported, despite the widespread distribution of kinases. The best linear model found was Kact = −9.44°β0(c) +10.94°β5(c) −2.40°β0(i) + 2.45°β5(m) + 0.73, where core (c), inner (i) and middle (m) refer to specific spatial protein regions. The model with a high Matthew's regression coefficient (0.79) correctly classified 206 out of 230 proteins (89.6%) including both training and predicting series. An area under the ROC curve of 0.94 differentiates our model from a random classifier. A subsequent principal components analysis of 152 heterogeneous proteins demonstrated that βkcodifies information different to other descriptors used in protein computational chemistry studies. Finally, the model recognizes 110 out of 125 kinases (88.0%) in a virtual screening experiment and this can be considered as an additional validation study (these proteins were not used in training or predicting series). © 2007 Wiley Periodicals, Inc. J Comput Chem 2007
On self duality of pathwidth in polyhedral graph embeddings
Authors: Fomin Fedor V. , Thilikos Dimitrios M. 
Published: February 2007

AbstractLet G be a 3‐connected planar graph and G* be its dual. We show that the pathwidth of G* is at most 6 times the pathwidth of G. We prove this result by relating the pathwidth of a graph with the cut‐width of its medial graph and we extend it to bounded genus embeddings. We also show that there exist 3‐connected planar graphs such that the pathwidth of such a graph is at least 1.5 times the pathwidth of its dual. © 2007 Wiley Periodicals, Inc. J Graph Theory 55: 42–54, 2007
Efficient and practical syntheses of a stable labelled form of the non‐narcotic analgesic, bicifadine and its metabolites
Authors: Chen Zhengming , Yang Ji , Little Gillian , Keats Andrew 
Published: February 2007

AbstractAn efficient and practical synthesis of deuterium‐labelled bicifadine, together with 3 deuterium‐labelled bicifadine metabolites, was developed. The levels of deuterium incorporation are high, and the products were used as internal standards in bioanalytical method development and clinical bioanalysis. Copyright © 2007 John Wiley & Sons, Ltd.
Effect of thermal treatment on the proteins of amaranth isolates
Authors: Avanza M Victoria , Añón M Cristina 
Published: February 2007

AbstractThe effect of thermal treatment of proteins from Amaranthus hypochondriacus was studied. Two protein isolates were obtained from the defatted flour by water extraction at a pH of 9 (A9 isolate) and 11 (A11 isolate), followed by isoelectric precipitation at a pH of 5. Effect of thermal treatment (70 and 90 °C, during 3, 5, 10, 15 and 30 min) on A9 and A11 dispersions were analyzed by differential scanning calorimetry (DSC), polyacrylamide gel electrophoresis, UV spectrophotometry, superficial hydrophobicity and solubility in water. Thermal treatment induced the aggregate formation of high molecular mass stabilized by disulfide and non‐covalent bond. Thermal treatment at 70 °C produced a 30% denaturation in both, while at 90 °C A9 was more denatured than A11 (75% and 55% of denaturation, respectively). An increase in thermal stability was also detected by DSC in A9 treated at 90 °C. The denaturation process was accompanied at short heating times by an increase in UV absorbance and changes in superficial hydrophobicity. A decrease in water solubility (35–50%, depending on time–temperature conditions) was also observed for the A9 isolates. The results suggest that the A9 isolates, enriched in a globulin protein fraction, are more sensitive to thermal treatment than isolates A11 enriched in glutelin protein fraction. The changes shown by both isolates, indeed, could affect their functional properties and could definitely limit their use in food products. Copyright © 2007 Society of Chemical Industry
A comparison between the properties of seed, starch, flour and protein separated from chemically hardened and normal kidney beans
Authors: Kaur Maninder , Singh Narpinder 
Published: February 2007

AbstractThe physicochemical, functional and thermal properties of starch, flour and protein isolates obtained from chemically hardened kidney beans were evaluated. A rapid chemical hardening procedure (soaking in acetate buffer, pH = 4.0, 37 °C, 6 h) was used to produce hardened kidney beans. Chemical hardening altered physicochemical, cooking, hydrating and textural properties of beans to a significant level (P < 0.05). Soaked and cooked chemically hardened beans had a higher value for different textural parameters than their normal counterparts. Chemical hardening increased cooking time (from 49 to 123 min) of beans and decreased swelling power and solubility of starch. The turbidity value of gelatinized starch suspensions from chemically hardened beans was significantly lower than that from normal beans. Chemical hardening of beans caused significant increase in transition temperatures (To, Tp, Tc) and enthalpy of gelatinization (ΔHgel) of both starch and flour. Chemically hardened bean starch showed significantly higher pasting temperature (94.9 °C) as compared to normal bean starch (83.2 °C). Flour and protein isolate from chemically hardened beans showed significantly lower water absorption, oil absorption, foaming capacity and gelling ability than those from normal beans. The onset temperature (Tm), peak denaturation temperature (Td) and heat of transition or enthalpy (ΔH) of protein isolate from hardened and normal beans did not differ significantly. Copyright © 2007 Society of Chemical Industry
Identification of dimer impurities in ampicillin and amoxicillin by capillary LC and tandem mass spectrometry
Authors: Lu Chi‐Yu , Feng Chia‐Hsien 
Published: February 2007

AbstractA micro‐scale liquid chromatography electrospray ionization tandem mass spectrometric method was developed for the identification of polymerized impurities in ampicillin and amoxicillin in aqueous solution. Ampicillin and amoxicillin are broad‐spectrum antibiotics and widely used for the treatment of human and animal infections. In this study ampicillin, amoxicillin, and their dimers were trapped in a 5‐cm capillary column containing C18 sorbents. The analytes were separated on a reversed‐phase column and introduced into the mass spectrometer via a nanospray ion source. An isocratic mobile phase consisting of 1% formic acid‐acetonitrile (50 : 50, v/v) was used. For identification, the fragment ions of the analytes were monitored. The aim of the present study was to develop an optimized quality control method for the analysis of high molecular weight impurities of ampicillin and amoxicillin.
Environmental sustainability in economic development: A comment
Authors: Goodland R. J. A. 
Published: February 2007

AbstractAlthough the linkages between economics and environment are absolute, they are not emphasized either by the economic or by the environmental professions. The economics of natural resources remains a minor unpopular theme in orthodox economics today. Similarly, the relationship of the economic subsystem to the overall ecosystem is only mentioned in most environmental science texts. Attention to the environmental dimensions of economic development burgeoned in the early 1970s and has yet to become systematic. There are encouraging signs that this is improving. The integration of economics and environmental studies has been the focus of several recent conferences and books, e.g. Brundtland, 1987; Conway, 1985; IIED, 1987; Jansson, 1984; Pearce, 1985 and at least two journals (Environmental Economics from 1976, and Ecology and Economics from 1987; excluding the vast literature mainly on pollution economics. This paper mentions four environmental aspects of economic development: the concept of sustainability, carrying capacity, ethics and irreversibility. It then focuses on one important irreversible—the loss of biodiversity—and outlines progress with the World Bank's policies in this regard.
Mechanism of UV‐Induced Gelation of Acryloyl‐Type Monomer and Polymer Solutions Using Persulfate as Photoinitiator
Authors: Ikkai Fumiyoshi , Adachi Eiki 
Published: February 2007

AbstractAn aqueous solution containing acryloyl‐type monomers or polymers undergoes gelation by UV irradiation in the presence of APS as UV‐photoinitiator. We investigate the mechanism of the UV‐induced gelation using LS and ESR. In LS, the dependence of the gelation time tgelation on the APS concentration CAPS is demonstrated for NIPAm solutions, and the relation between CAPS and tgelation fits a power law function, i.e., tgelation ∼ C, indicating that UV‐induced gelation progresses according to a radical polymerization mechanism. On the other hand, ESR data reveal that the UV‐induced cross‐linking reaction takes place at α‐carbon atoms in acryloyl‐type monomers and polymers.magnified image
Parametrized Littlewood–Paley operators on Hardy and weak Hardy spaces
Authors: Ding Yong , Lu Shanzhen , Xue Qingying 
Published: February 2007

AbstractIn this paper, we give the boundedness of the parametrized Littlewood–Paley function $ \mu ^{*,\rho}_{\lambda} $ on the Hardy spaces and weak Hardy spaces. As the corollaries of the above results, we prove that $ \mu ^{*,\rho}_{\lambda} $ is of weak type (1, 1) and of type (p, p) for 1 < p < 2, respectively. This results are substantial improvement and extension of some known results. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)