bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of di‐n‐dodecyl phosphate on the transesterification reaction in a poly(butylene terephthalate)/polycarbonate blend
Authors: Lei Caihong , Chen Dahua 
Published: April 2008

AbstractThe transesterification behavior of a poly(butylene terephthalate) (PBT)/polycarbonate (PC) blend with the addition of di‐n‐dodecyl phosphate was studied with differential scanning calorimetry (DSC) and infrared spectroscopy. The effects of triphenyl phosphate (TPP) and di‐n‐dodecyl phosphate on the suppression of transesterification were compared. The differences in the crystallization and melting temperatures during the two heating and cooling cycles in the DSC measurements were lower than those of the virgin PBT/PC blend, and di‐n‐dodecyl phosphate inhibited the formation of a random copolyester but did not suppress the formation of a block copolyester. The crystallization temperature of the PBT/PC blend in the presence of di‐n‐dodecyl phosphate was higher than that of the blend in the presence of TPP. Di‐n‐dodecyl phosphate was thus more effective than TPP in the inhibition of transesterification between PBT and PC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.
Mechanical and morphological characteristics of poly(vinyl alcohol)/chitosan hydrogels
Authors: Mathews D. T. , Birney Y. A. , Cahill P. A. , McGuinness G. B. 
Published: April 2008

AbstractThe effect of freeze–thaw cycles and chitosan type (water‐soluble or insoluble) on the morphological and mechanical characteristics of poly(vinyl alcohol) (PVA)/chitosan hydrogels was investigated with scanning electron microscopy (SEM), uniaxial testing, and a biaxial tubular vessel inflation experiment. SEM images showed that although multiple freeze–thaw cycles had no significant effect on pore size for PVA hydrogels without chitosan, both types of PVA–chitosan hydrogel developed a more porous structure with a greater distribution of pore size. Uniaxial mechanical tests demonstrated decreasing elasticity for successive freeze–thaw cycles within a range comparable to porcine aortic tissue. A conditioning effect, which modified the elastic response of the hydrogels after the first loading cycle, was also shown. Coefficients for hyperelastic material models were determined for the PVA–chitosan (water‐soluble) hydrogels. The internal pressurization and axial extension of a tubular vessel within the physiological range was investigated experimentally and compared with the predictions of a numerical model. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Formation of porous PLGA scaffolds by a combining method of thermally induced phase separation and porogen leaching
Authors: Yang Yanfang , Zhao Jin , Zhao Yunhui , Wen Liang , Yuan Xiaoyan , Fan Yubo 
Published: April 2008

AbstractA novel method for the fabrication of porous poly(L‐lactide‐co‐glycolide) (PLGA) scaffolds by combining thermally induced phase separation and porogen leaching is presented in this article. Big pores with about 75–400 μm diameters in the obtained scaffolds were generated by the porogen, sucrose particles, while small pores with diameters less than 20 μm induced via phase separation. Extraction of the solvent, chloroform by ethanol at cool temperatures could reduce the scaffold toxicity. Effects of PLGA concentration, freezing temperature, volume fraction of porogen, and introduction of β‐tricalcium phosphate (β‐TCP) on morphology, porosity, and compressive properties of the scaffolds were systematically discussed. Results showed that the size of small pores decreased by decreasing the polymer concentration and reducing the freezing temperature, whereas the interconnectivity of the scaffolds was improved by increasing the porogen fraction. The compressive modulus and strength were significantly lowered by increasing the scaffold porosity, that is, by increasing porogen fraction, or decreasing the polymer concentration, or reducing the freezing temperature. Addition of β‐TCP into the scaffolds did not influence the compressive modulus significantly but tended to decrease the compressive strength. The obtained scaffolds with diverse pore sizes would be potentially used in bone tissue engineering. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Interphase modeling of copper‐epoxy particulate composites subjected to static and dynamic loading
Authors: Papanicolaou G. C. , Xepapadaki A. G. , Kotrotsos A. , Mouzakis D. E. 
Published: April 2008

AbstractIn this investigation, the static and dynamic behavior of copper‐filled epoxy particulate composites has been experimentally studied. The influence of particle‐weight fraction (0–25%), on the static behavior and filler concentration, temperature and frequency on the dynamic behavior of the mentioned particulate composites was thoroughly studied. Experimental results for the static three‐point bending modulus were compared with respective theoretical predictions derived from that existing in literature semiempirical models. Results were also compared with predictions derived by the application of the interphase model previously developed by the first author for the evaluation of the elastic modulus in particulate composites, taking into account the effect of filler‐matrix adhesion. It was found that the predicted values as derived from the application of the interphase model were in better agreement with experimental findings when compared with respective predictions derived from other models. Polymer‐filler degree of adhesion was also studied by applying the Turcsànyi model. Extended SEM investigations and DMA tests were also made to support both experimental and theoretical findings. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effects of vinyltrimethoxy silane on thermal properties and dynamic mechanical properties of polypropylene–wood flour composites
Authors: Bouza Rebeca , Lasagabaster Aurora , Abad María José , Barral Luis 
Published: April 2008

AbstractThe viability of vinyltrimethoxy silane was investigated as a coupling agent for the manufacture of wood–plastic composites (WPC). The effect of silane pretreatment of the wood flour on the thermal and the dynamic mechanical properties and thermal degradation properties of the composites were studied. Moreover, the effect of organosilane on the properties of composites was compared with the effect of maleated polypropylene (MAPP). DSC studies indicated that the wood flour acts as a PP‐nucleating agent, increasing the PP crystallization rate. In general, pretreatment with small amounts of silane improved this behavior in all the WPCs studied. Thermal degradation studies of the WPCs indicated that the presence of wood flour delayed degradation of the PP. Silane pretreatment of the wood flour augmented this effect, though without significantly affecting cellulose degradation. Studies of dynamic mechanical properties revealed that the wood flour (at up to 30 wt %) increased storage modulus values with respect to those of pure PP; in WPCs with a higher wood flour amount, there was no additional increase in storage modulus. Pretreatment of the wood flour with silane basically had no effect on the dynamic mechanical properties of the WPC. These results show that with small amounts of vinyltrimethoxy silane similar properties to the MAPP are reached. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Thermal characterisation of photo‐oxidized HDPE/Mater‐Bi and LDPE/Mater‐Bi blends buried in soil
Authors: Moriana‐Torró R. , Contat‐Rodrigo L. , Santonja‐Blasco L. , Ribes‐Greus A. 
Published: April 2008

AbstractBlends of high and low density polyethylene with a commercial biodegradable material (Mater‐Bi) were subjected to an accelerated soil burial test. A set of samples was previously photo‐oxidized to evaluate the effects of UV‐irradiation on the degradation in soil process of these blends. Thermogravimetric as well as calorimetric analysis were performed to study the biodegradation, photo‐degradation and their synergetic effects. Differential scanning calorimetry was carried out to analyze the morphological changes as a consequence of the photo‐oxidation process. UV‐irradiation slightly modifies the crystalline content of HDPE/Mater‐Bi blends, increasing the heterogeneity of this blend. Criado master curves were plotted to analyses the degradation kinetic model. Broido and Coats‐Redfern methods have been used for calculating the Ea of the thermal decomposition mechanisms. Thermogravimetric results reveal that noncomplexed starch is more affected by biodegradation than the polyethylene matrix and the starch/EVOH complexes chains from Mater‐Bi. However, the effects of both photo‐oxidation and biodegradation processes on the thermal decomposition of Mater‐Bi is influenced by the polymeric matrix used. Previous photo‐oxidation finds to slow down the degradative effects caused by the soil burial test on the HDPE/Mater‐Bi blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and characterization of new methacrylate‐type hydrogels containing 2‐tert‐butylamino ethyl groups for sorption purposes
Authors: Bayramgil Nursel Pekel 
Published: April 2008

AbstractCrosslinked poly[2‐(tert‐butylamino)ethyl methacrylate] (PtBAEMA) hydrogels were synthesized by 60Co‐γ‐radiation‐initiated simultaneous polymerization and crosslinking of 2‐(tert‐butylamino)ethyl methacrylate in bulk and in aqueous solutions. The results showed that the gelation percentage decreased with increasing water content. The structural and thermal characterizations of the hydrogels were accomplished with several techniques, including Fourier transform infrared spectroscopy, swelling measurements, thermogravimetry, and differential scanning calorimetry. The effects of time, pH, temperature, and ionic strength on the swelling behavior were also investigated. Swelling equilibrium was attained in 2–3 days. PtBAEMA hydrogels originally swelled to 350% (by volume) in deionized water, but this value reached 3000% around pH 2.0. PtBAEMA hydrogels were reversibly affected by the change in temperature within the temperature range of 4–70°C. The swelling ratios of the gels decreased with increasing ionic strength. As a result, PtBAEMA hydrogels show stimuli‐responsive properties depending on the characteristics of the environment, and they are being considered for adoption as some kind of carrying material for separation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
The application of cell‐based label‐free technology in drug discovery
Authors: Xi Biao , Yu Naichen , Wang Xiaobo , Xu Xiao , Abassi Yama 
Published: April 2008

AbstractCell‐based assays are an important part of the drug discovery process allowing for interrogation of targets and pathways in a more physiological setting compared to biochemical assays. One of the main hurdles in the cell‐based assay field is to design sufficiently robust assays with adequate signal to noise parameters while maintaining the inherent physiology of the pathway or target being investigated. Conventional label and reporter‐based cell assays may be more prone to artifacts due to considerable manipulation of the cell either by the label or over‐expression of targets or reporter proteins. Cell‐based label‐free technologies preclude the need for cellular labeling or over‐expression of reporter proteins, utilizing the inherent morphological and adhesive characteristics of the cell as a physiologically relevant and quantitative readout for various cellular assays. Furthermore, these technologies utilize non‐invasive measurements allowing for time resolution and kinetics in the assay. In this article, we have reviewed the various label‐free technologies that are being used in drug discovery settings and have focused our discussion on impedance‐based label‐free technologies and its main applications in drug discovery.
Identification of optimal measurement sets for complete flux elucidation in metabolic flux analysis experiments
Authors: Chang YoungJung , Suthers Patrick F. , Maranas Costas D. 
Published: April 2008

AbstractMetabolic flux analysis (MFA) methods use external flux and isotopic measurements to quantify the magnitude of metabolic flows in metabolic networks. A key question in this analysis is choosing a set of measurements that is capable of yielding a unique flux distribution (identifiability). In this article, we introduce an optimization‐based framework that uses incidence structure analysis to determine the smallest (or most cost‐effective) set of measurements leading to complete flux elucidation. This approach relies on an integer linear programming formulation OptMeas that allows for the measurement of external fluxes and the complete (or partial) enumeration of the isotope forms of metabolites without requiring any of these to be chosen in advance. We subsequently query and refine the measurement sets suggested by OptMeas for identifiability and optimality. OptMeas is first tested on small to medium‐size demonstration examples. It is subsequently applied to a large‐scale E. coli isotopomer mapping model with more than 17,000 isotopomers. A number of additional measurements are identified leading to maximum flux elucidation in an amorphadiene producing E. coli strain. Biotechnol. Biotechnol. Bioeng. 2008;100: 1039–1049. © 2008 Wiley Periodicals, Inc.
Practical identifiability of biokinetic parameters of a model describing two‐step nitrification in biofilms
Authors: Brockmann D. , Rosenwinkel K.‐H. , Morgenroth E. 
Published: April 2008

AbstractParameter estimation and model calibration are key problems in the application of biofilm models in engineering practice, where a large number of model parameters need to be determined usually based on experimental data with only limited information content. In this article, identifiability of biokinetic parameters of a biofilm model describing two‐step nitrification was evaluated based solely on bulk phase measurements of ammonium, nitrite, and nitrate. In addition to evaluating the impact of experimental conditions and available measurements, the influence of mass transport limitation within the biofilm and the initial parameter values on identifiability of biokinetic parameters was evaluated. Selection of parameters for identifiability analysis was based on global mean sensitivities while parameter identifiability was analyzed using local sensitivity functions. At most, four of the six most sensitive biokinetic parameters were identifiable from results of batch experiments at bulk phase dissolved oxygen concentrations of 0.8 or 5 mg O2/L. High linear dependences between the parameters of the subsets ${\rm (}K_{{\rm O}_{\rm 2} {\rm ,AOB}} {\rm ,}\,\mu _{{\rm AOB}} {\rm )}$ and ${\rm (}K_{{\rm O}_{\rm 2} {\rm ,NOB}} {\rm ,}\,\mu _{{\rm NOB}} {\rm )}$ resulted in reduced identifiability. Mass transport limitation within the biofilm did not influence the number of identifiable parameters but, in fact, decreased collinearity between parameters, especially for parameters that are otherwise correlated (e.g., µAOB and $K_{{\rm O}_{\rm 2} {\rm ,AOB}} $, or µNOB and $K_{{\rm O}_{\rm 2} {\rm ,NOB}} $). The choice of the initial parameter values had a significant impact on the identifiability of two parameter subsets, both including the parameters µAOB and $K_{{\rm O}_{\rm 2} {\rm ,AOB}} $. Parameter subsets that did not include the subsets µAOB and $K_{{\rm O}_{\rm 2} {\rm ,AOB}} $ or µNOB and $K_{{\rm O}_{\rm 2} {\rm ,NOB}} $ were clearly identifiable independently of the choice of the initial parameter values. Biotechnol. Bioeng. 2008;101: 497–514. © 2008 Wiley Periodicals, Inc.
A new device to close secundum atrial septal defects: First clinical use to close multiple defects in a child
Authors: Halabi Ali , Hijazi Ziyad M. 
Published: April 2008

AbstractTranscatheter device closure of secundum atrial septal defects (ASD) has become an accepted treatment modality. Currently, the only device that can be used for large defects is the Amplatzer Septal Occluder. We report on a new device (Occlutech Figulla), to close multiple ASDs in a child with two large defects using 12 and 15 mm devices. © 2008 Wiley‐Liss, Inc.
Prospective randomized comparison of sirolimus‐ versus paclitaxel‐eluting stents for the treatment of acute ST‐elevation myocardial infarction
Authors: Lee Jae‐Hwan , Kim Hyun‐Sook , Lee Seung‐Whan , Park Jae‐Hyeong , Choi Si‐Wan , Jeong Jin‐Ok , Cho Yoonhaeng , Lee Naehee , Rhee Kyoung‐Suk , Ko Jae‐Ki , Seong In‐Whan 
Published: April 2008

AbstractObjective: The aim of this study was to compare effectiveness of the Sirolimus‐ (SES) and Paclitaxel‐eluting stent (PES) in primary angioplasty for acute ST‐elevation myocardial infarction (STEMI). Background: It has been reported that SES and PES have been more effective than bare‐metal stents in reducing restenosis and cardiac events in a broad range of patients with coronary artery disease. However, it is unknown whether there may be differences between these two drug‐eluting stents in terms of efficacy in the setting of acute STEMI. Methods: Acute STEMI patients (n = 308) undergoing primary angioplasty were randomly assigned to SES (n = 154) or PES (n = 154) deployment. The routine angiographic follow‐up was performed at 6 months and clinical follow‐up data was obtained at 12 months. The primary end point was major adverse cardiac events (MACE) including death, reinfarction, stent thrombosis, and target lesion revascularization (TLR) at 12 months. Results: The baseline clinical, angiographic, and procedural characteristics were similar between the 2 groups. Two patients (all from the PES group) experienced stent thrombosis (1 acute and 1 subacute). The SES group revealed lower in‐segment restenosis (5.9% vs. 14.8%, P = 0.03) and in‐segment late loss (0.09 ± 0.45 vs. 0.33 ± 0.68 mm, P = 0.002) than PES group on follow‐up angiography. Twelve‐month TLR rates (2.6% vs. 6.5%, P = 0.17) were similar between two groups. MACE rates were lower in the SES group than in the PES group, but it did not reach statistical significance (5.8% vs. 11.7%, P = 0.07). Conclusion: In the setting of primary angioplasty for STEMI, there were no statistically significant differences between the SES and the PES in terms of 12‐month MACE. However, binary angiographic in‐segment restenosis and in‐segment late loss were significantly lower in the SES group. © 2008 Wiley‐Liss, Inc.
Percutaneous management of cyanosis in Fontan patients using Amplatzer occluders
Authors: Masura Jozef , Borodacova Lucia , Tittel Peter , Berden Pavel , Podnar Tomaž 
Published: April 2008

AbstractObjectives: To determine causes of cyanosis and to evaluate percutaneous management of cyanosis in a group of consecutive Fontan patients. Background: A variety of communications allow a right‐to‐left shunt in Fontan circulation causing cyanosis and these communications are amenable to percutaneous closure. Methods: Between November 1997 and November 2007, 45 consecutive patients ranging in age from 2.5 to 26 years (median 8 years) with Fontan circulation and cyanosis underwent cardiac catheterization and percutaneous closure of superfluous communications using different types of Amplatzer occluders. Results: Altogether, 51 communications were detected and 50 of them were closed. In 5 patients (11.1%), multiple communications were present and were closed. Fenestration was detected in 37 of 41 patients (90.2%) after total cavopulmonary connection and all were closed by Amplatzer septal occluders. Five venous collaterals were revealed in 3 of 41 patients (7.3%) with total cavopulmonary anastomosis and were closed by Amplatzer vascular plugs. In 3 patients, lateral tunnel leaks were detected and were closed by Amplatzer PFO occluders. In 4 patients after Kawashima operation, 3 major pulmonary arterio‐venous malformations and single venous collateral contributed to the cyanosis and all were closed using Amplatzer vascular plugs. Conclusions: Different communications cause cyanosis in Fontan patients. Progressive decline of percutaneous oxygen saturation is suggestive of development of venous collaterals or pulmonary arteriovenous malformations. Superfluous communications are amenable to percutaneous closure using various types of Amplatzer occluders. A novel use of an Amplatzer PFO occluder for the percutaneous closure of a lateral tunnel leak is described. © 2008 Wiley‐Liss, Inc.
Thrombectomy during PCI for acute myocardial infarction
Authors: Antoniucci David , Valenti Renato , Migliorini Angela 
Published: April 2008

AbstractMacro and microembolization during percutaneous coronary intervention (PCI) in ST elevation acute myocardial infarction (STEAMI) is frequent and may result in obstruction of the microvascular network with subsequent reduction in efficacy of reperfusion. Numerous mechanistic studies have shown that the presence and size of the culprit thrombus is the most powerful predictor of incidence of embolization and slow flow/no reflow. Techniques that have been used to reduce the incidence of these events include thrombectomy devices and embolic protection devices. Although numerous prospective randomized clinical trials have been performed to evaluate the role of thrombectomy devices in patients with STEAMI, the results of these trials are conflicting and they speak to both sides of the controversy. The Achilles heal of the majority of these trials is the premise that thrombectomy devices should be routinely used in all patients presenting with STEAMI even irrespective of the presence and size of the thrombus. Such a hypothesis is naively optimistic and it ignores the basic knowledge available to us regarding the relationship between thrombus burden and embolization. Nonetheless, clinicians are faced every day with the reality of making difficult decisions on how to best treat patients presenting with STEAMI and large thrombus burden. The current available “evidence‐based medicine” cannot and should not be generalized to these patients because only a minority of these patients was included in these randomized clinical trials. In these patients, thrombectomy devices should be strongly considered as an integral part of the armamentarium available to reduce thrombus burden prior to definitive treatment. Whether a future clinical trial will provide a definitive answer in terms of clinical outcome difference is doubtful because such a trial will need to include large number of selected patients with STEAMI who both have large amount of myocardium at jeopardy and large thrombus burden, a difficult and possibly undoable study. © 2008 Wiley‐Liss, Inc.
Two years experience of a simple technique of precise ostial coronary stenting
Authors: Wong Philip 
Published: April 2008

AbstractObjective: To evaluate a new technique of precise ostial coronary stenting without relying solely on angiography. Background: Precise stent positioning at ostial coronary stenosis is difficult because angiography may not be able to profile the coronary ostium, due to vessel overlap and/or foreshortening. This problem is compounded by bobbing or to and fro movement of the stent with cardiac contraction. Methods: A new technique of precise ostial stenting not dependant on angiography was utilized. A guidewire in a side branch was threaded through the most proximal stent cell and the stent was advanced into the target vessel until it was stopped at the carina. The stent was deployed and the side guidewire withdrawn. All results were documented by intravascular ultrasound (IVUS). Results: From October 2005 to October 2007, 58 patients with significant ostial coronary stenosis required stenting. Seventeen patients were treated in the conventional manner and the remaining 41 patients with the new technique. The ostial locations included 8 left main, 25 left anterior descending, 3 circumflex, 1 obtuse marginal, 3 right coronary, and 1 posterior descending artery. Success, as confirmed by IVUS, was achieved in 40 patients (97.6%). Failure occurred in a right coronary ostial stenosis, which was subsequently treated by the conventional method. There were no complications. Conclusion: This new technique is highly successful in cases of difficulty in stenting ostial stenosis guided solely by conventional angiography. © 2008 Wiley‐Liss, Inc.