bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local injection of thrombin‐related peptide (TP508) in PPF/PLGA microparticles–enhanced bone formation during distraction osteogenesis
Authors: Wang Yan , Wan Chao , Szöke George , Ryaby James T. , Li Gang 
Published: October 2007

AbstractWe have previously demonstrated that injections of the thrombin‐related peptide, TP508, into the lengthening gap have significantly enhanced bone consolidation in a rabbit model of distraction osteogenesis. This study was to further test the effect of a single TP508 injection in slow release preparation on bone formation during distraction osteogenesis. Rabbits had left tibiae lengthened unilateral lengthener at rate of 1.4 mm/day for 6 days. TP508 was injected into as the following: Group 1, TP508 in saline; Group 2, in PPF/PLGA [poly(propylene fumarate)/poly(D,L‐lactic‐co‐glycolic acid)] microparticles; and Group 3, dextran gel only. All the animals were killed 2 weeks after lengthening. On radiographies, more bone was formed in the two TP508‐treated groups at first and secnd week postlengthening than that of the control Group 3. Microcomputed tomography (microCT) at 2 weeks indicated that the most advanced bone formation and remodeling was seen in Group 2. The mean volumetric BMD of the regenerates was significantly higher in the TP508 treated groups compared to the control group (p < 0.05). Histological evaluations supported the radiographic and the microCT results. In conclusion, we have demonstrated that a single injection of small amount of TP508 (300 µg) at the end of lengthening phases has significantly enhanced bone consolidation process in a rabbit model of distraction osteogenesis. The delivery of TP508 in PPF/PLGA microparticles appears to lead to a better quality bone formation over the saline delivery, further examinations are needed to confirm if PPF/PLGA microparticles may be desirable drug delivery form in augmenting bone formation. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:539–546, 2008
Prediction of final tumor response to preoperative chemotherapy by Tc‐99m MIBI imaging at the middle of chemotherapy in malignant bone and soft tissue tumors: Comparison with Tl‐201 imaging
Authors: Taki Junichi , Higuchi Takahiro , Sumiya Hisashi , Tsuchiya Hiroyuki , Minato Hiroshi , Tomita Katsuro , Tonami Norihisa 
Published: October 2007

AbstractThe aim of this study was to assess the predictive power of 99mTc‐MIBI scintigraphy performed in the middle of chemotherapy, for the final tumor response to chemotherapy, and compare it to that of 201Tl in malignant bone and soft tissue tumors (MBST). Sixty‐eight patients with MBST underwent 99mTc‐MIBI and 201Tl scintigraphies at 15 min after tracer injection before the first, and after the third, chemotherapy cycles. After five cycles of chemotherapy and tumor resection, therapeutic effect was assessed by histopathology. Less than 90% and ≥90% necrosis were judged as poor and good response to chemotherapy, respectively. Tracers uptake ratios were calculated by dividing the lesion count density by that of the background. 99mTc‐MIBI perfusion index was also calculated. The % reduction of the perfusion index (ΔPI) and uptake ratios (ΔUR) calculated by 100 × [(prechemotherapy value − postchemotherapy value)/prechemotherapy value] were compared with histologic response. The sensitivity, specificity, and accuracy for the prediction of effective chemotherapy in 99mTc‐MIBI imaging were 80%, 95%, 88% in ΔUR, and 74%, 74%, 74% in ΔPI, respectively. The area under the receiver operator characteristic curve (Az) of the 99mTc‐MIBI‐ΔUR (0.923) was significantly higher than that of ΔPI (0.809, p = 0.025) but only marginally higher than that of the 201Tl‐ΔUR (0.865, p = 0.079). Az in 201Tl (0.865) was not significantly different from that of ΔPI (0.809, p = 0.35). 99mTc‐MIBI imaging performed in the middle of chemotherapy well predicts the final tumor response to chemotherapy in patients with malignant bone and soft tissue tumors. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:411–418, 2008
An Overview of Important Microstructural Distributions for Polyolefin Analysis
Authors: Soares João B.P. 
Published: October 2007

AbstractSummary: Polyolefins with complex microstructures are becoming increasingly common in academic and industrial applications. Polyolefin analytical techniques are evolving to provide a more detailed picture of these microstructures, with the development and improvement of hyphenated‐techniques and cross‐fractionation methods. These modern analytical techniques provide a wealth of information on polyolefin microstructure and, despite being extremely useful, they can also be hard to interpret without the help of mathematical models that link polymerization kinetics to chain microstructure and polymer characterization results. In this paper we review some of the most important distributions for polyolefin microstructure and derive a few new expressions that help understand the results obtained with several polyolefin characterization techniques.
Characterization of Ethylene‐1‐Hexene Copolymers Made with Supported Metallocene Catalysts: Influence of Support Type
Authors: Paredes Beatriz , Soares João B.P. , van Grieken Rafael , Carrero Alicia , Suarez Inmaculada 
Published: October 2007

AbstractSummary: It is known that the nature of the support, as well as the technique used to anchor the metallocene onto it, play important roles on catalytic activity and on the properties of the polymers produced with supported metallocenes. In the present work, the effect of different support types on the microstructure of ethylene/1‐hexene copolymers made with supported metallocene catalysts has been investigated through the analysis of molecular weight and chemical composition distributions using high temperature gel permeation chromatography (GPC) and crystallization analysis fractionation (Crystaf). The copolymer samples obtained using commercial carriers (silica and silica‐alumina) had unimodal chemical composition distributions and were used to create a linear calibration curve relating the peak crystallization temperature from Crystaf and the comonomer content as determined by 13C NMR. This calibration curve is useful to determine the 1‐hexene fractions for each peak in the resins showing bimodal chemical composition distributions, such as those obtained with catalysts supported on MCM‐41 and SBA‐15 materials. The structure and chemistry of the support used had a large influence on comonomer incorporation and the shape of the chemical composition distribution of the polymer, which suggests that the supporting process creates different types of active sites.
Application of Fractionation Techniques to the Study of Olefin Polymerization Kinetics and Polymer Degradation
Authors: Nakatani Hisayuki , Matsuoka Hitoshi , Suzuki Shoutarou , Taniike Toshiaki , Boping Liu , Terano Minoru 
Published: October 2007

AbstractSummary: Temperature rising elution fractionation (TREF) has been regarded as a powerful technique for study of semicrystalline polymers. In this paper, two examples of unique applications of TREF were introduced. One was the study on the influence of extraction of internal donor on the variation of isospecific active sites of a MgCl2‐ supported Ziegler catalyst, and the other was the estimation of the relationship between polymer micro‐tacticity and degradation rate of isotactic polypropylene (iPP). The former example revealed the conversion from high to low isospecific site by the extraction of internal donors, whereas the latter showed a negative correlation between the level of isotacticity and the degradation rate. These results demonstrated that TREF was useful in these research applications.
Synthesis and Characterization of Ethylene/Propylene Copolymers in the Whole Composition Range
Authors: Caballero Ma. Joaquina , Suarez Inmaculada , Coto Baudilio , Van Grieken Rafael , Monrabal Benjamín 
Published: October 2007

AbstractSummary: The incorporation of comonomer molecules in the backbone of a homopolymer can influence the final properties of the material, decreasing its crystallinity and the melting and glass transition temperatures, and increasing its impact resistance and transparency. In the present work, ten ethylene/propylene copolymers have been synthesized using a supported metallocene catalytic system covering the whole composition range. Any desired composition was obtained by controlling the feed composition during the reaction. These synthesized copolymers have been characterized by different techniques in order to study the effect of the comonomer incorporation onto their final properties. When the comonomer content is low, the behaviour of the copolymer is similar to that of the corresponding homopolymer. Nevertheless, if the comonomer content increases, the copolymer becomes more amorphous (low crystallization temperature and soft XRD signals) and easily deformable, reaching a behaviour close to that corresponding to an elastomeric material. In order to corroborate these results the samples have been characterized by TREF and GPC‐MALS. TREF analysis showed that copolymers containing less than 10% and more than 80% of ethylene are semicrystalline, with elution temperatures typical of this kind of polymers. Molecular weights are higher for homopolymers and they decrease as the comonomer concentration increases, whereas the polydispersity index keeps almost constant at the expected value for this kind of samples.
Characterization of Polyethylene Nascent Powders Synthesized with TpTiCl2(OR) Catalysts
Authors: Casas Emilio , Karam Arquímedes , Díaz‐Barrios Antonio , Albano Carmen , Sánchez Yanixia , Méndez Bernardo 
Published: October 2007

AbstractSummary: Different kinds of polyethylene and ethylene‐1‐hexene copolymers were synthesized with TpTiCl2(OR) (Tp = hydrotris(pyrazolyl)borate; R = Et, i‐Pr, n‐Bu) catalysts with and without H2. The polymers were characterized by 13C NMR, capillary viscosimetry or GPC, and DSC. The homopolymers showed properties characteristic of ultra‐high molecular weight polyethylenes (UHMWPE) with linear structure and high density polyethylenes (HDPE) with molecular weights in the range of commercial grades under hydrogen atmosphere. The copolymers showed a 1‐hexene incorporation up to 6 mol‐%. Important differences in the thermal properties were observed between the first DSC (nascent powders) and the second DSC heatings (melt‐crystallized samples), which evidenced the molecular weights influence on the melt‐crystallized samples.
Characterization of LDPE grafted with Diethylmaleate by Gamma Radiation: Application of FTIR, GPC and SSA Techniques
Authors: Sánchez Y. , Albano C. , Perera R. , Karam A. , Silva P. 
Published: October 2007

AbstractSummary: The grafting of diethyl maleate onto low‐density polyethylene using gamma irradiation as initiator has been evaluated. The grafting degree was estimated by FTIR and with the use of a calibration curve. The functionalized polymers were characterized by DSC, MFI, SSA and GPC. An increase in the grafting degree with the radiation dose and the concentration of the functional monomer was found. Branching seemed to be the preferential reaction induced by radiation, causing an increase in average molecular weights with the consequently reduction of melt flow index values. The molecular segregation induced by the calorimetric treatment showed that grafting occurs preferentially through secondary carbon sequences.
Boundary integral method for Stokes flow past a porous body
Authors: Kohr Mirela , Raja Sekhar G. P. , Wendland Wolfgang L. 
Published: October 2007

AbstractIn this paper we obtain an indirect boundary integral method in order to prove existence and uniqueness of the classical solution to a boundary value problem for the Stokes–Brinkman‐coupled system, which describes an unbounded Stokes flow past a porous body in terms of Brinkman's model. Therefore, one assumes that the flow inside the body is governed by the continuity and Brinkman equations. Some asymptotic results in both cases of large and, respectively, of low permeability are also obtained. Copyright © 2007 John Wiley & Sons, Ltd.
Comparing treatment effects after adjustment with multivariable Cox proportional hazards regression and propensity score methods
Authors: Martens Edwin P. , de Boer Anthonius , Pestman Wiebe R. , Belitser Svetlana V. , Stricker Bruno H. Ch. , Klungel Olaf H. 
Published: October 2007

AbstractPurposeTo compare adjusted effects of drug treatment for hypertension on the risk of stroke from propensity score (PS) methods with a multivariable Cox proportional hazards (Cox PH) regression in an observational study with censored data.MethodsFrom two prospective population‐based cohort studies in The Netherlands a selection of subjects was used who either received drug treatment for hypertension (n = 1293) or were untreated ‘candidates’ for treatment (n = 954). A multivariable Cox PH was performed on the risk of stroke using eight covariates along with three PS methods.ResultsIn multivariable Cox PH regression the adjusted hazard ratio (HR) for treatment was 0.64 (CI95%: 0.42, 0.98). After stratification on the PS the HR was 0.58 (CI95%: 0.38, 0.89). Matching on the PS yielded a HR of 0.49 (CI95%: 0.27, 0.88), whereas adjustment with a continuous PS gave similar results as Cox regression. When more covariates were added (not possible in multivariable Cox model) a similar reduction in HR was reached by all PS methods. The inclusion of a simulated balanced covariate gave largest changes in HR using the multivariable Cox model and matching on the PS.ConclusionsIn PS methods in general a larger number of confounders can be used. In this data set matching on the PS is sensitive to small changes in the model, probably because of the small number of events. Stratification, and covariate adjustment, were less sensitive to the inclusion of a non‐confounder than multivariable Cox PH regression. Attention should be paid to PS model building and balance checking. Copyright © 2007 John Wiley & Sons, Ltd.
Positron annihilation study of PbWO4 crystal doped with Y2O3 at different concentration
Authors: Xie Jianjun , Geng Zhengsong , Yuan Hui , Xiong Wei , Chen Liang , Ye Chongzhi , Xu Guoqing , Hao Xiaopeng , Zhang Zhiming , Ma Hongliang , Gu Mu , Feng Xiqi , Liao Jingying 
Published: October 2007

AbstractA study of vacancy‐related defects in yttrium‐doped PbWO4 with doping concentration of 0–1 mol% has been performed using X‐ray diffraction and positron annihilation lifetime spectroscopy. It was found that the samples have vacancy‐like defects that act as positron traps. Two main defect lifetime components were found in all samples, one at about 0.195 ns to 0.208 ns and the other about 0.408 ns to 0.735 ns. These defect trapping sites can be attributed to single Pb‐site vacancies and interstitial oxygen ions, respectively. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Construction of confidence limits about effect measures: A general approach
Authors: Zou G. Y. , Donner A. 
Published: October 2007

AbstractIt is widely accepted that confidence interval construction has important advantages over significance testing for the presentation of research results, as now facilitated by readily available software. However, for a number of effect measures, procedures are either not available or not satisfactory in samples of small to moderate size. In this paper, we describe a general approach for estimating a difference between effect measures, which can also be used to obtain confidence limits for a risk ratio and a lognormal mean. Numerical evaluation shows that this closed‐form procedure outperforms existing methods, including the bootstrap. Copyright © 2007 John Wiley & Sons, Ltd.
Sample size formulae for trials comparing group and individual treatments in a multilevel model
Authors: Moerbeek Mirjam , Wong Weng Kee 
Published: October 2007

AbstractIn disease screening and prevention trials, subjects in the experimental condition are frequently nested within therapy groups, whereas subjects in the control group receive individual or no therapy and are therefore not nested within groups. Outcomes of subjects within the same therapy group are expected to be more alike than outcomes of subjects within different therapy groups. Ignoring this dependency in the design stage may result in less powerful designs. This paper presents a multilevel model for analyzing such trials and sample size formulae for continuous and binary outcomes with unequal variances and costs across groups. The proposed optimal design ensures that there is adequate power to detect a treatment effect with either minimal cost or a minimal number of subjects. We apply our strategy and design an improved trial where all subjects with musculoskeletal pain received conventional therapy and subjects in the intervention arm participated in a group‐learning program. Copyright © 2007 John Wiley & Sons, Ltd.
Mechanism of action and effectiveness of ester thiols as thermal stabilizers for poly(vinyl chloride)
Authors: Ge Xianlong , Culyba Elizabeth K. , Grinnell Cole L. , Zestos Alexander G. , Starnes William H. 
Published: October 2007

AbstractOrganic thiols containing at least one carboxylate ester group (ester thiols) are excellent thermal stabilizers for both rigid and plasticized poly(vinyl chloride) (PVC). Their mechanism of action is shown to involve the deactivation of unstable structural defects by nucleophilic chloride displacement, the retardation and removal of coloration through thiol additions to polyene double bonds, and the prevention of autoacceleration during thermal dehydrochlorination through polyene shortening reactions and the scavenging of free radicals formed from polyenes and HCl. An unusually facile displacement of labile chloride that is favored by thiol acidity can account, at least in part, for the relatively high effectiveness of dipentaerythritol hexakis(mercaptoacetate) as a stabilizer. J. VINYL ADDIT. TECHNOL., 13:170–175, 2007. © 2007 Society of Plastics Engineers
Method for assessing impact of large‐scale wind power integration on reserves
Authors: Norheim Ian , Pudjianto Danny 
Published: October 2007

AbstractConcerns have been raised due to the impact that large‐scale wind power integration will have on reserves and secure operation of power systems. Case studies on a simplified model of the UK system with large penetration of wind power in Scotland are presented for illustration. A method called stepwise power flow was used to simulate the impact of wind power generation fluctuation output on the system frequency, reserves and power flow. It was demonstrated that the supply–demand imbalance caused by forecast errors in wind power production and load, and fall out of wind power production would influence the system frequency, system bias and the use of reserves. This method can also be used to estimate the amount of wind power that can be integrated before the system experiences serious problems due to inadequacy of the available reserves. Copyright © 2007 John Wiley & Sons, Ltd.
System efficiency of a DC/DC converter‐based wind farm
Authors: Max Lena , Lundberg Stefan 
Published: October 2007

AbstractIn this paper, three DC/DC converter topologies are evaluated from an energy efficiency point of view regarding their suitability for the application in a DC wind farm grid. The three investigated topologies are the fullbridge (FB) converter, the single active bridge (SAB) converter and the series parallel resonant (LCC) converter. The energy efficiency of the three converter topologies is evaluated for different control strategies. It is found that the LCC and FB converters have the lowest losses of the three topologies. It is also shown that the wide range of operation creates problems for all three converters. The SAB converter has the largest increase in losses caused by the wide range of operation. The FB converter also has an increase in losses for this variable operating range, whereas the LCC converter has large stresses for the input and output filters. By considering some further factors, such as the contribution to the energy production cost, the design and the control of the converters, the FB converter is found to be a suitable choice for wind farm application. Copyright © 2007 John Wiley & Sons, Ltd.
A Saccharomyces cerevisiae cell‐based quantitative β‐galactosidase assay compatible with robotic handling and high‐throughput screening
Authors: de Almeida Rogerio Alves , Burgess Danielle , Shema Reut , Motlekar Nuzhat , Napper Andrew D. , Diamond Scott L. , Pavitt Graham D. 
Published: October 2007

AbstractReporter‐gene assays that employ the Escherichia coli lacZ gene are ubiquitously employed in biological research. However, we were not able to readily identify a quantitative method that worked reliably with yeast (Saccharomyces cerevisiae) cells and that was compatible with high‐throughput screening and robotic liquid handling tools. We have therefore adapted a commercially available assay employing a 6‐O‐β‐galactopyranosyl–luciferin substrate to provide the required sensitivity with minimal sample handling times. Our assay uses only one‐tenth of the reagents suggested by the reagent manufacturer (Promega) for equivalent assays with mammalian cell cultures and produces rapid, sensitive and reproducible analysis with as little as 1 µl yeast cell culture and with < 100 cells. We demonstrate that the assay is compatible with yeast strains generated by the systematic yeast deletion project and functions equally well with genomically integrated or plasmid‐encoded lacZ reporters and with cells grown in complex or defined media. The high‐sensitivity, miniaturized format reduced sample handling required will make this assay useful for a wide range of applications. Copyright © 2007 John Wiley & Sons, Ltd.
Benefit of Ultrasonography in the Detection of Clinically and Mammographically Occult Breast Cancer
Authors: Chan Sharon W. W. , Cheung Polly S. Y. , Chan Stefanie , Lau Suk Sze , Wong Ting Ting , Ma Michael , Wong Ada , Law Yuen Ching 
Published: October 2007

AbstractObjectiveThe purpose of this study was to evaluate the performance of high‐resolution ultrasonography in the detection of clinically and mammographically occult breast cancer.Materials and methodsFrom September 2003 to November 2006, a total of 1485 patients were confirmed to have in situ or invasive breast cancer in Hong Kong Sanatorium and Hospital Breast Care Centre. All patients underwent mammography (MMG) and/ or sonography (USG) evaluation. Patients’ age and size of tumor detected by USG alone were compared with those detected by MMG.ResultsAltogether, 222 patients (17%) had positive imaging findings on USG only, among which 22 (13%) patients had nonpalpable tumors. Performing USG increased the cancer detection rate among clinically and mammographically occult breast lesions by 14.3%. The mean size of the tumors detected only by USG was 1.98 cm, which was not significantly different from the mean size of tumor detected by MMG (1.46) (p = 0.23). This remains true in the group of patients with nonpalpable tumors (1.36 vs. 1.46 cm, p = 0.88). The sensitivity of USG is 91%, which is significantly higher than that of MMG (78%) (p = 0.001). This remains true in patients age <40 or ≥40, tumor grading I toIII, and LVI +/− cases. However, MMG had higher sensitivity in the group of patients with nonpalpable tumors (73% vs. 62%, p = 0.01) and noninvasive cancers (72% vs. 69%, p = 0.01).ConclusionsThe use of high‐resolution USG may lead to detection of a significant number of occult cancers that are no different in size from nonpalpable mammographically detected lesions.