bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of Melatonin in Rat Pineal Gland and Drug with Flow‐Injection Chemiluminescence
Authors: Wei Shou‐Lian , Zhao Li‐Xia , Cheng Xiang‐Lei , Lin Jin‐Ming 
Published: April 2007

AbstractA flow‐injection chemiluminescence (CL) method for the determination of melatonin based on the CL reaction of melatonin with hydrogen peroxide and sodium hypochlorite (NaOCl) in a basic alkaline solution was developed. The possible CL mechanism has been discussed, and a proposal for the reaction pathway was given that singlet oxygen was clarified to be produced in this reaction system and was responsible for the CL emission. Under the optimized conditions, the linear concentration range of application was 1.0×10−7–2.5×10−4 mol·L−1 with a detection limit of 5.0×10−8 mol·L−1 (S/N=3). The relative standard deviation for eight repeated measurements of 1.0×10−6 mol·L−1 melatonin was 2.8%. The interferences of several important biological substances, some indole compound, cations and anions were studied. No interference was found for the anions, glucose, starch, most of cations and low concentration (less than 3.0×10−6 mol·L−1) of some biological substances and indole compound. The method was applied to the determination of melatonin in rat pineal gland and drug with satisfactory results. The sample throughput was 90 injections per hour.
Characterization of TiO2 Loaded on Activated Carbon Fibers and Its Photocatalytic Reactivity
Authors: Jia Bing‐Yu , Duan Li‐Yan , Ma Chuan‐Li , Wang Chun‐Ming 
Published: April 2007

AbstractIn this paper, TiO2 loaded on activated carbon fibers (ACF) was prepared by a coating treatment, followed by calcination at different temperatures in air atmosphere. The photocatalyst developed was characterized by SEM, XRD, XPS and UV‐Vis adsorption spectroscopy. It was observed from SEM images that TiO2 loaded on ACF was in the form of small clusters with nanometer size. As confirmed by XRD and XPS determinations, the crystalline pattern of immobilized TiO2 was still anatase‐form after calcination, and the micrographic structure and surface properties of ACF have not been damaged by the deposition process and calcination at different temperatures. Photocatalytic degradation of methylene blue (MB) in aqueous solution was investigated using TiO2/ACF as photocatalyst. The comparison of photolysis, absorption and photocatalysis was carried out. The results indicated that the photocatalysis process of combined photocatalyst showed much higher degradation rate than that of photolysis and absorption processes. In addition, the possibility of cyclic usage of the photocatalyst was also confirmed.
Discrete design method of transverse gradient coils for MRI
Authors: Shvartsman Shmaryu , Steckner Michael C. 
Published: April 2007

AbstractA method is presented for designing transverse gradient coils for magnetic resonance imaging. This method is based on the set of Z intercepts of the coils' current patterns with the z axis in the unfolded z‐arc plane. We show that the set of Z intercepts combined with a description of the coil topology, as defined by the necessary azimuthal harmonics, the axial symmetry and the directions of the current flow, is sufficient for designing a practical gradient coil. The theory and design of transverse coils with Z intercepts is illustrated with examples of a symmetric unshielded insert gradient coil for small animal imaging, a human head unshielded symmetric insert gradient coil with shoulder cutouts, and a self‐shielded short whole‐body gradient coil. The Z‐intercept method has also been extended to design higher‐order transverse shims. This is illustrated with the design of a ZX shim. Additional design capabilities of the Z‐intercepts method are also discussed. © 2007 Wiley Periodicals, Inc.Concepts Magn Reson Part B (Magn Reson Engineering) 31B: 95–115, 2007.
Mexiletine has a local anesthetic effect on sciatic nerve blockade in rats
Authors: Cheng Kuang‐I , Shieh Ja‐Ping , Lin Ching‐Nan , Chu Koung‐Shing , Kwan Aij‐Lie , Hou Chia‐Hui , Wang Jhi‐Joung 
Published: April 2007

AbstractMexiletine is an antiarrhythmic drug that has a Na+channel blocking activity. The aim of the present study was to evaluate whether mexiletine had a local anesthetic effect as assessed by sciatic nerve blockade. Thus, the potency and duration of action of mexiletine on sciatic nerve blockade in terms of motor function and nociception were evaluated. Two local anesthetics, bupivacaine and lidocaine, were used as controls. Mexiletine produced a dose‐related local anesthetic effect on sciatic nerve blockade. The rank potency was bupivacaine >lidocaine >mexiletine (P<0.05 for each comparison). On an equi‐potent basis, the rank duration of action was bupivacaine>mexiletine>lidocaine (P<0.05 for each comparison). Co‐administration of mexiletine with bupivacaine produced an additive effect on sciatic nerve blockade. In conclusion, mexiletine had a local anesthetic effect on sciatic nerve blockades of motor function and nociception. Co‐administration of mexiletine with bupivacaine produced an additive effect on sciatic nerve blockade. Drug Dev. Res. 67:905–909, 2006. © 2007 Wiley‐Liss, Inc.
Performance of TCP on low‐bandwidth wireless links with delay spikes
Authors: Lassila Pasi , Kuusela Pirkko 
Published: April 2007

AbstractWe model the goodput of a single TCP source on a wireless link experiencing sudden increases in Round Trip Time (RTT), that is delay spikes. Such spikes trigger spurious timeouts that reduce the TCP goodput. Renewal reward theory is used to derive a straightforward expression for TCP goodput that takes into account limited sending rates (limited window size), lost packets due to congestion and the delay spike properties such as the average spike duration and distribution of the spike intervals. The basic model is for independent and identically distributed (i.i.d.) spike intervals, and correlated spike intervals are modelled by using a modulating background Markov chain. Validation by ns2 simulations shows excellent agreement for lossless scenarios and good accuracy for moderate loss scenarios (for packet loss probabilities less than 5%). Numerical studies have also been performed to assess the impact of different spike interval distributions on TCP performance. Copyright © 2007 John Wiley & Sons, Ltd.
YZβ discontinuity capturing for advection‐dominated processes with application to arterial drug delivery
Authors: Bazilevs Y. , Calo V. M. , Tezduyar T. E. , Hughes T. J. R. 
Published: April 2007

AbstractThe YZβ discontinuity‐capturing operator, recently introduced in (Encyclopedia of Computational Mechanics, Vol. 3, Fluids. Wiley: New York, 2004) in the context of compressible flows, is applied to a time‐dependent, scalar advection–diffusion equation with the purpose of modelling drug delivery processes in blood vessels. The formulation is recast in a residual‐based form, which reduces to the previously proposed formulation in the limit of zero diffusion and source term. The NURBS‐based isogeometric analysis method, proposed by Hughes et al. (Comput. Methods Appl. Mech. Eng. 2005; 194:4135–4195), was used for the numerical tests. Effects of various parameters in the definition of the YZβ operator are examined on a model problem and the better performer is singled out. While for low‐order B‐spline functions discontinuity capturing is necessary to improve solution quality, we find that high‐order, high‐continuity B‐spline discretizations produce sharp, nearly monotone layers without the aid of discontinuity capturing. Finally, we successfully apply the YZβ approach to the simulation of drug delivery in patient‐specific coronary arteries. Copyright © 2007 John Wiley & Sons, Ltd.
Modelling the effects of emergent vegetation on an open‐channel flow using a lattice model
Authors: Jiménez‐Hornero Francisco J. , Giráldez Juan V. , Laguna Ana M. , Bennett Sean J. , Alonso Carlos V. 
Published: April 2007

AbstractA two‐dimensional lattice model has been developed to describe the influence of vegetation on the turbulent flow structure in an open channel. The model includes the influence of vegetation density on the frictional effect of the channel bed and walls. For the walls, a semi‐slip boundary condition has been considered as an
alternative to overcome the no‐slip boundary condition limitations in turbulent flows. The drag stress exerted by the flow on the vegetation as well as the gravity effect has also been taken into account. The proposed lattice model has been used to simulate the experimental results reported from the study of the influence of alternate vegetated zones on the open‐channel flow. The results show that the lattice model approach is a valid tool for describing these kinds of flows. Copyright © 2007 John Wiley & Sons, Ltd.
Adaptive VOF with curvature‐based refinement
Authors: Malik Mayank , Fan Eric Sheung‐Chi , Bussmann Markus 
Published: April 2007

AbstractAdaptive refinement is implemented in the context of the volume‐of‐fluid (VOF) methodology in order to study the efficacy of resolving interfaces adaptively based on the local value of curvature. The usual uniform mesh VOF implementation is modified slightly to ensure accurate advection of fluxes between cells at different resolutions. Normals and curvatures are calculated accurately via height functions. Results of a series of tests indicate that in most instances the use of adaptive refinement (when compared to uniform refinement with a similar number of cells) leads to more accurate VOF advection. The results also clearly show that curvature‐based adaptive refinement leads to a distribution of errors along an interface that is nearly independent of curvature. Copyright © 2007 John Wiley & Sons, Ltd.
Genetic influences on human brain structure: A review of brain imaging studies in twins
Authors: Peper Jiska S. , Brouwer Rachel M. , Boomsma Dorret I. , Kahn René S. , Hulshoff Pol Hilleke E. 
Published: April 2007

AbstractTwin studies suggest that variation in human brain volume is genetically influenced. The genes involved in human brain volume variation are still largely unknown, but several candidate genes have been suggested. An overview of structural Magnetic Resonance (brain) Imaging studies in twins is presented, which focuses on the influence of genetic factors on variation in healthy human brain volume. Twin studies have shown that genetic effects varied regionally within the brain, with high heritabilities of frontal lobe volumes (90–95%), moderate estimates in the hippocampus (40–69%), and environmental factors influencing several medial brain areas. High heritability estimates of brain structures were revealed for regional amounts of gray matter (density) in medial frontal cortex, Heschl's gyrus, and postcentral gyrus. In addition, moderate to high heritabilities for densities of Broca's area, anterior cingulate, hippocampus, amygdala, gray matter of the parahippocampal gyrus, and white matter of the superior occipitofrontal fasciculus were reported. The high heritability for (global) brain volumes, including the intracranium, total brain, cerebral gray, and white matter, seems to be present throughout life. Estimates of genetic and environmental influences on age‐related changes in brain structure in children and adults await further longitudinal twin‐studies. For prefrontal cortex volume, white matter, and hippocampus volumes, a number of candidate genes have been identified, whereas for other brain areas, only a few or even a single candidate gene has been found so far. New techniques such as genome‐wide scans may become helpful in the search for genes that are involved in the regulation of human brain volume throughout life. Hum Brain Mapp, 2007. © 2007 Wiley‐Liss, Inc.
Expression of B7‐H1 in breast cancer patients is strongly associated with high proliferative Ki‐67‐expressing tumor cells
Authors: Ghebeh Hazem , Tulbah Asma , Mohammed Shamayel , ElKum Naser , Amer Suad M. Bin , Al‐Tweigeri Taher , Dermime Said 
Published: April 2007

AbstractB7‐H1, a coinhibitory molecule, plays a role in immune escape of tumors. We have shown previously the expression of this molecule in breast cancer patients and demonstrated its association with high histological grade, progesterone and estrogen receptor negative status, all of which are known to have direct impact on cell proliferation. In the present work, we investigated the effect of proliferation, as measured by Ki‐67 and mitotic count, on the induction of B7‐H1. We used H&E stained sections to score for mitotic count in 69 breast cancer patients. Immunohistochemistry was used to investigate B7‐H1 and Ki‐67 expression. The relationship between B7‐H1 induction and cell proliferation was further investigated in primary cultured cells. B7‐H1 expression was recorded in patients with a high mitotic index (p = 0.007). There was a high significant correlation between B7‐H1 expression and the presence of the proliferative marker Ki‐67 (p < 0.001) indicating the association of proliferation with B7‐H1 induction. Furthermore, B7‐H1 was gradually induced in proliferating cells of 8/8 primary cell lines as measured by Ki‐67 expression. Finally, B7‐H1 was downregulated in quiescent cells and upregulated in cells stimulated with a mitogen confirming the association of proliferation with the induction of B7‐H1. We have shown for the first time a direct association between proliferation and the expression of B7‐H1 in breast cancer patients. The relationship between B7‐H1 induction and cell proliferation was also thoroughly investigated in vitro, in which a strong link between B7‐H1 expression and the presence of the proliferative Ki‐67 marker was clearly demonstrated. © 2007 Wiley‐Liss, Inc.
Monodisperse polystyrene microspheres by dispersion copolymerization of styrene and other vinyl comonomers: Characterization and protein adsorption properties
Authors: Hou Xiaohui , Liu Bailing , Deng Xiaobo , Zhang Baotan , Yan Jufang 
Published: April 2007

AbstractDispersion polymerization is a very attractive method for preparing micron‐size monodisperse polymeric microspheres. The applications of microspheres have been greatly extended by using comonomers. In the present study, five kinds of polystyrene microspheres of 4–6 μm in diameters bearing different surface functional groups were synthesized by copolymerization of styrene and various vinyl comonomers. Their surface physicochemical characteristics were examined, including average particle size and size distribution, concentration of surface functional groups, as well as hydrophobicity. Concentration of FT‐IR spectra of different samples were also discussed. The effects of microspheres' surface physicochemical properties on the isotherms of adsorption and chemisorption of BSA were determined. The results show that microspheres bearing different surface function groups have different capacity of protein adsorption. Besides, since the protein adsorption behaviors were more complex than the ideal adsorption model, the isotherms could not fit Freundlich model very well. Possible reasons were discussed. Knowledge gained from these results may be utilized for rational design of carriers of receptors and antibodies used in solid‐phase immunoassay, especially Scintillation proximity assay in High‐throughput Screening. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Structural and mechanical evaluations of a topology optimized titanium interbody fusion cage fabricated by selective laser melting process
Authors: Lin Chia‐Ying , Wirtz Tobias , LaMarca Frank , Hollister Scott J. 
Published: April 2007

AbstractA topology optimized lumbar interbody fusion cage was made of Ti‐Al6‐V4 alloy by the rapid prototyping process of selective laser melting (SLM) to reproduce designed microstructure features. Radiographic characterizations and the mechanical properties were investigated to determine how the structural characteristics of the fabricated cage were reproduced from design characteristics using micro‐computed tomography scanning. The mechanical modulus of the designed cage was also measured to compare with tantalum, a widely used porous metal. The designed microstructures can be clearly seen in the micrographs of the micro‐CT and scanning electron microscopy examinations, showing the SLM process can reproduce intricate microscopic features from the original designs. No imaging artifacts from micro‐CT were found. The average compressive modulus of the tested caged was 2.97 ± 0.90 GPa, which is comparable with the reported porous tantalum modulus of 3 GPa and falls between that of cortical bone (15 GPa) and trabecular bone (0.1–0.5 GPa). The new porous Ti‐6Al‐4V optimal‐structure cage fabricated by SLM process gave consistent mechanical properties without artifactual distortion in the imaging modalities and thus it can be a promising alternative as a porous implant for spine fusion. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Host response to sponge implants differs between subcutaneous and intraperitoneal sites in mice
Authors: Mendes Juliana B. , Campos Paula P. , Ferreira Mônica A. N. D. , Bakhle Y. S. , Andrade Silvia P. 
Published: April 2007

AbstractSynthetic matrices have been used widely to repair and/or to replace biological tissues. However, there is relatively little information on the effect of different anatomical compartments on the host response to foreign implants. We have analyzed such responses to sponge implants in subcutaneous and in intraperitoneal sites in mice at days 3, 5, and 8 postimplantation by measuring inflammation, angiogenesis, and production of proangiogenic/inflammatory cytokines. The angiogenic response, assessed by hemoglobin content and by morphometric analysis of the number of vessels, was higher in intraperitoneal implants. Levels of vascular endothelial growth factor in intraperitoneal implants were 14‐fold higher than in subcutaneous implants at day 3 and remained high for the next 5 days. Neutrophil accumulation as determined by myeloperoxidase activity was the same in both types of implants. Macrophage accumulation (N‐acetylglucosaminidase activity) was also similar on days 3 and 8 in both implants. Levels of the chemokine CXCL2/KC were always higher, but those of CCL2/JE lower, in the intraperitoneal implant. These results demonstrate that the anatomical site of the implant markedly influenced the host response to synthetic matrices. Our results provide a greater understanding of factors affecting the biocompatibility of exogenous materials placed at different anatomical sites. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Time dependent mechanical properties of bone cement. An in vitro study over one year
Authors: Nottrott Markus , Mølster Anders Odd , Gjerdet Nils Roar 
Published: April 2007

AbstractChanges in mechanical properties of bone cements over time are of clinical importance, but not well documented. Specifications for testing do not address the time factor. This study recorded changes in compressive properties and microstructure of one bone cement stored under simulated physiological conditions (water at 37°C) from 20 min up to 1 year and in dry air at 37°C for comparison. Compressive strength increased within the first week (p < 0.001), decreased at 1 month (p < 0.001), and remained at that level at 1 year. Elastic modulus showed a similar development. Maximum strain values, indicating plastic deformability, increased continuously over 1 year. Microscopy revealed microcracks between the pre‐polymer beads and the matrix in specimens tested after 20 min, whereas there were less cracks in 1 year specimens. Increase in strength during the first week is due to polymerization and formation of interpenetrating molecular networks. The subsequent decrease could be due to the plasticizing effect of water uptake, as supported by higher values for dry specimens. It can be speculated that microcracks which could be initiated while reducing an arthroplasty at 15 min, acting as initiators for fatigue fractures in the cement mantle, contribute to cement failure. It is recommended that testing of bone cements should be performed after extended ageing at simulated physiological conditions, for the present cement at least 5 weeks. Results obtained at less than one week could be influenced by ongoing polymerization, as well as microcracks and lower coherence between the prepolymer beads and the matrix. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Polyurethane hydrogel colored contact lens with gradient water content
Authors: Chen Yongjun , Narayanswamy Babu , Chew Mike 
Published: April 2007

AbstractA colored contact lens was fabricated by chemically bonding a layer of polyurethane (PU) hydrogel color ink to the bulk soft clear lens. The water content of the PU hydrogel was lower than that of the soft contact lens bulk materials, which provided the appropriate gradient water content of the colored lens. The gradient water content of the colored lens reduced the dehydration of the colored lens and minimized the interface stress between bulk lens surface and color ink layer. The colored lens showed much better comfort and dryness ratings than those of the other commercial color lens and even the clear soft lens used in this study. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
The sperm nuclear matrix is required for paternal DNA replication
Authors: Shaman Jeffrey A. , Yamauchi Yasuhiro , Steven Ward W. 
Published: April 2007

AbstractThe mammalian sperm nucleus provides an excellent model for studying the relationship between the formation of nuclear structure and the initiation of DNA replication. We previously demonstrated that mammalian sperm nuclei contain a nuclear matrix that organizes the DNA into loop domains in a manner similar to that of somatic cells. In this study, we tested the minimal components of the sperm nucleus that are necessary for the formation of the male pronucleus and for the initiation of DNA synthesis. We extracted mouse sperm nuclei with high salt and dithiothreitol to remove the protamines in order to form nuclear halos. These were then treated with either restriction endonucleases to release the DNA not directly associated with the nuclear matrix or with DNAse I to digest all the DNA. The treated sperm nuclei were injected into oocytes, and the paternal pronuclear formation and DNA synthesis was monitored. We found that restriction digested sperm nuclear halos were capable of forming paternal pronuclei and initiating DNA synthesis. However, when isolated mouse sperm DNA or sperm DNA reconstituted with the nuclear matrices were injected into oocytes, no paternal pronuclear formation or DNA synthesis was observed. These data suggest that the in situ nuclear matrix attachment organization of sperm DNA is required for mouse paternal pronuclear DNA synthesis. J. Cell. Biochem. 102: 680–688, 2007. © 2007 Wiley‐Liss, Inc.