bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermally stable and amorphous polyfluorene
Authors: Kwag Gwanghoon , Park Eunjoo , Lee Soo No 
Published: March 2005

AbstractTwo‐dimensional ladder‐type polyfluorenes, which consist of polystyrene as the polymer backbone and polyfluorene as the light emitting component, were prepared through three synthetic pathways A, B, and C. In path A, the precursor polymer IP1 was obtained from the graft reaction of fluorene to units of poly(vinylbenzyl chloride) and then the ladder‐type polymer P1 was prepared by coupling at the 2,7‐position of fluorene with FeCl3 as an oxidizing agent in chloroform. In path B, IP2 was obtained from the graft reaction of lithiated 2,7‐dibromofluorene and units of poly(vinylbenzyl chloride), and then P2 was prepared by the aryl‐coupling of IP2 with a Ni‐catalyst through the reductive polymerization. In path C, 4‐(fluorenylmethyl)styrene was prepared by the reaction of 4‐chloromethylstyrene and lithiated fluorene. Fluorene‐attached syndiotatic polystyrene, IP3, was obtained in the polymerization of 4‐(fluorenylmethyl)styrene with CpTiCl3‐MAO catalyst, and for P3 oxidative coupling was further carried out. The polymers exhibited glass transition temperatures (Tg) of 422°C for P1, 404°C for P2, and 311°C for P3, and no melting endotherms were found. Syndiotaticity contributes the high glass temperature of P3 despite low molecular weight. Thermal decomposition temperatures at 5 wt % loss (Td) of 475°C for P1, 448°C for P2, and 365°C for P3 were observed. The fluorescence peaks of P1, P2, and P3 were observed at 401, 416, and 415 nm, respectively. For the emission spectrum of P3, no shoulder or peak regarding of aggregation of polyfluorene was observed. Syndiotacticity, due to the alternative configuration of fluorene, prevents a large Stoke's shift of the luminescence spectrum. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1335–1340, 2005
Synthesis and properties of starch grafted poly[acrylamide‐co‐(acrylic acid)]/montmorillonite nanosuperabsorbent via γ‐ray irradiation technique
Authors: Luo Wei , Zhang Wei'An , Chen Peng , Fang Yue'e 
Published: March 2005

AbstractThe novel nanosuperabsorbent copolymer (NSAP) was synthesized by grafting copolymerization of acrylamide (AM) and acrylic acid (AA) onto starch with montmorillonite (MMT) initiated using 60Co γ‐ray irradiation. NSAP was characterized by IR spectroscopy and X‐ray diffraction (XRD). Different synthesis parameters were studied, such as AM‐to‐AA ratio, radiation total dose, radiation dose rate, crosslinker content, and clay content. NSAP can effectively improve the water retention capacity of soil. The effects of NSAP on crops were also studied, showing that NSAP has an encouraging potential for agricultural application. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1341–1346, 2005
Lamellae orientation effect on local polarized domain in P(VDF/TrFE) copolymer: Application in data storage
Authors: El‐Hami K. , Matsushige K. 
Published: March 2005

AbstractIn our previous article we achieved a high planar orientation of the poly(vinylidene fluoride and trifluoroethylene) [P(VDF/TrFE)] crystalline lamellae.1 This short article focuses and reports our studies on the effect of this lamella orientation on its local polarized domains. Two samples A and B are considered in this investigation. In many parts of the film area, the lamella nanocrytals were oriented parallel to the substrate along a unidirectional axis by a newly conceived method, which consists of depositing a thin film on the clean surface of distilled water (sample A). In the second type (sample B), a film was prepared on highly oriented pyrolytic graphite (HOPG) by spin‐coating, showing random and entangled lamellae in the amorphous phase. Atomic force microscopy (AFM) has been used to investigate morphological development and the local poled domain during an applied bias voltage for both A and B samples. The results showed that a minimum bias voltage of +3 V was enough to observe the local poled domain in the case of oriented lamellae (sample A) while there was no piezoresponse measured in the case of random lamellae (sample B). When we increased the applied bias voltage, sample B showed a recorded local domain as a piezoresponse while in the case of sample A the local domain was enlarged. We can suggest that, during the preparation of sample A, the macromolecules had a preferential stable position where the dipole moments did not need a strong bias voltage to be switched but cross to the coercive voltage Vc. The character of oriented lamella nanocrytals can minimize the poling voltage in ferroelectric organic ultrathin films and will have an advantageous influence on production of a high‐functionality mass memory device in data storage. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1410–1413, 2005
Palladium‐Catalyzed Suzuki Couplings of 2,3‐Dibromonorbornadiene: Synthesis of Symmetrical and Unsymmetrical Aryl‐Substituted Norbornadienes
Authors: Yoo Woo‐Jin , Tsui Gavin C. , Tam William 
Published: March 2005

AbstractPalladium‐catalyzed Suzuki coupling reactions between 2,3‐dibromonorbornadiene and arylboronic acids were investigated. These reactions provide an efficient method for the synthesis of symmetrical 2,3‐diarylnorbornadienes which are not accessible using the traditional Diels–Alder cycloaddition reactions. The optimized reaction conditions of the Suzuki coupling reactions were found using [Pd2(dba)3] (0.5 mol%), tBu3P (1.4 mol%) and CsF in THF. High yields of the Suzuki coupling products were obtained when electron‐rich arylboronic acids were used. On the other hand, Suzuki coupling reactions with electronic‐deficient or sterically hindered arylboronic acids gave lower yields of the corresponding 2,3‐di‐arylnorbornadienes. Unsymmetrical mono‐ and diaryl‐substituted norbornadienes were also prepared in good yields using this method. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Comparison of sheathless and sheath‐flow electrospray interfaces for the capillary electrophoresis‐electrospray ionization‐mass spectrometry analysis of peptides
Authors: Sanz‐Nebot Victoria , Balaguer Elvira , Benavente Fernando , Barbosa José 
Published: March 2005

AbstractCapillary electrophoresis coupled to mass spectrometry via an electrospray interface provides a powerful system for separation and characterization of a high number of biomolecules. The present paper describes a home‐made sheathless interface and compares it with a commercial sheath‐flow interface, using a separation method based on a peptide hormone mixture of therapeutic interest. In a previous work, we optimized the parameters involved in a sheath‐flow interface and obtained good results in sensitivity and reproducibility. The sheathless interface is performed with a graphite‐coated electrospray ionisation (ESI) tip attached to the separation capillary. We demonstrate that electrolyte composition is the main parameter affecting signal sensitivity and separation resolution. The effect of the nature and concentration of the organic solvent added to the separation electrolyte is carefully studied. Furthermore, a general comparison of both interfaces is made in terms of separation, reproducibility, and sensitivity obtained under the optimized conditions described. Advantages and disadvantages of both coupling setups have been evaluated.
Highly branched HK peptides are effective carriers of siRNA
Authors: Leng Qixin , Scaria Puthupparampil , Zhu Jingsong , Ambulos Nicholas , Campbell Patricia , Mixson A. James 
Published: March 2005

AbstractBackgroundBoth viral and nonviral carriers have been used to carry small interfering RNA molecules (siRNA) to their cytosolic mRNA target. To date, few peptide carriers have been developed that have proved effective for siRNA delivery. Our previous branched carriers composed of histidine and lysine were useful for transfection of plasmids. In this study, we determined if these and more highly branched HK polymers were effective carriers of siRNA.MethodsSeveral branched polymers were synthesized on a Ranin Voyager synthesizer. These polymers were then screened for their ability to transfer siRNA into SVR‐bag4 cells, MDA‐MB‐435 cells, and C6 cells. After one polymer, H3K8b, was identified as an effective carrier of siRNA, additional polymers were synthesized to determine the essential domains for siRNA transport. The size/zeta‐potential of HK : siRNA complexes were measured with the N4 submicron particle size analyzer and the Delsa 440 SX zeta‐potential analyzer, respectively. Toxicity of the highly branched polymers in complex with siRNA was investigated by flow cytometry.ResultsIn an endothelial cell line (SVR‐bag4) that stably expressed β‐galactosidase (β‐gal), an siRNA in complex with the H3K8b polymer inhibited β‐gal expression by more than 80%. In contrast, the polymer H2K4b, which was an effective carrier of plasmids, was not an efficient carrier of siRNA. The size and surface charge did not distinguish effective from ineffective HK carriers of siRNA. By modifying H3K8b, we then determined what properties of H3K8b augmented siRNA delivery. The histidine‐rich domain and the length of the terminal arms of H3K8 were important for siRNA delivery. The modestly more effective analog of H3K8b containing an integrin ligand, H3K8b(+RGD), was able to inhibit markedly intracellular β‐gal expression. Furthermore, we determined that H3K8b(+RGD) in complex with a luciferase‐targeting siRNA inhibited luciferase expression in MDA‐MB‐435 cells. At its optimal concentration for inhibiting its target, H3K8b(+RGD) : siRNA complex had minimal toxicity. In contrast, carriers of siRNA such as Oligofectamine and Lipofectamine 2000 were significantly more toxic.ConclusionsBoth the degree of complexity and the sequence specificity are important factors to be considered for developing the HK carrier of siRNA. In particular, we found that certain branched HK polymers (H3K8b, H3K8b(+RGD), and similar structural analogs) with eight terminal branches and a histidine‐rich domain were effective carriers of siRNA. Copyright © 2005 John Wiley & Sons, Ltd.
Rheological Properties of Different Film Blowing Polyethylene Samples Under Shear and Elongational Flow
Authors: La Mantia Francesco P. , Scaffaro Roberto , Carianni Graziana , Mariani Paolo 
Published: March 2005

AbstractSummary: The rheological behavior of polyethylenes is mainly dominated by the molecular weight, the molecular weight distribution and by the type, the amount and the distribution of the chain branches. In this work a linear metallocene catalyzed polyethylene (m‐PE), a branched metallocene catalyzed polyethylene (m‐bPE), a conventional linear low density polyethylene (LLDPE) and a low density polyethylene (LDPE) have been investigated in order to compare their rheological behavior in shear and in elongational flow. The four samples have similar melt flow index and in particular a value typical of film blowing grade. The melt viscosity has been studied both in shear and in isothermal and non‐isothermal elongational flow. The most important features of the results are that in shear flow the m‐PE sample shows less pronounced non Newtonian behavior while in the elongational flow the behavior of m‐PE is very similar to that of the linear low density polyethylene: the narrower molecular weight distribution and the better homogeneity of the branching distribution are reasonably responsible for this behavior. Of course the most pronounced non‐linear behavior is shown, as expected, by the LDPE sample and by the branched metallocene sample. This similar behavior has to be attributed to the presence of branching. Similar comments hold in non‐isothermal elongational flow; the LDPE sample shows the highest values of the melt strength and the other two samples show very similar values. As for the breaking stretching ratio the opposite is true for LDPE while m‐PE and LLDPE show higher values. The transient isothermal elongational viscosity curves show that the branched samples show a strain hardening effect, while LLDPE and m‐PE samples present a linear behavior.Dimensionless flow curves of different polyethylene samples.magnified imageDimensionless flow curves of different polyethylene samples.
Hairy Nanospheres by Gelation of Reactive Block Copolymer Micelles
Authors: Du Jianzhong , Chen Yongming 
Published: March 2005

AbstractSummary: A novel way to prepare polymer hair/polysilsesquioxane core hybrid nanospheres is presented based on a self‐assembly and gelation process of a reactive block copolymer, poly(ethylene oxide)‐block‐poly[3‐(trimethoxysilyl)propyl methacrylate] (PEO113‐b‐PTMSPMA206). Nanospheres of uniform size were obtained. Transmission electron microscopy (TEM), dynamic light scattering (DLS), and static light scattering (SLS) were employed to characterize the products.Schematic of the PEO‐b‐PTMSPMA nanospheres formed here, the light gray part represents the PEO hairs, the dark parts are the polysilsesquioxane from the gelation of the PTMSPMA blocks of the self‐assembled sphere.imageSchematic of the PEO‐b‐PTMSPMA nanospheres formed here, the light gray part represents the PEO hairs, the dark parts are the polysilsesquioxane from the gelation of the PTMSPMA blocks of the self‐assembled sphere.
A Six Sigma Approach to Predicting Corporate Defaults
Authors: Neagu Radu , Hoerl Roger 
Published: March 2005

AbstractThe progression of a corporation from a status of financial stability into the status of financial distress usually happens over relatively large periods of time, raising the opportunity of identifying these ‘falling’ corporations ahead of time. Consequently, a critical risk management objective is to provide investment portfolio managers with an early notice of deteriorating financial status for a corporation. We consider a model built using equity inferred Probability of Default (PD) metrics. We follow a Design for Six Sigma Define, Measure, Analyze, Design, Verify (DMADV) approach to enhance the predictability power of the PD by constructing a two‐dimensional risk space for estimating likelihood of default. We use such techniques as classification and regression tree (CART) analysis and logistic regression, and build a control plan using censored data analysis. We test our model on two actual portfolios. The potential savings revealed by these tests are significant, re‐assuring us of the performance of our methodology. Copyright © 2005 John Wiley & Sons, Ltd.
Endofullerenes with small silver and copper clusters
Authors: Gurin V. S. 
Published: March 2005

AbstractModels of endofullerenes C60 with small metal clusters Agn and Cun (n < 5) were built and calculated with the self‐consistent field Hartree–Fock (SCF HF) MOLCAO method, using an effective core potential for silver and all‐electronic basis sets for copper. Binding energies of the clusters shows that monoatomic M@C60 structures are stable for both silver and copper. The models Mn@C60 (n = 2, 3, 4) with copper are much more favorable than those with silver. Metal atoms and clusters in the C60 molecule provide noticeable changes in its geometry, but the large distortion of the clusters does not correspond to stable structures. Stable Mn@C60 with MCu reveal the electronic charge transfer from metal atoms to the carbon cage, resulting in the positive charge of metal atoms. Models Cu2@C60 and Cu4@C60 with tetrahedron Cu4 are proposed as possible candidates in real metal–fullerene systems. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Simultaneous measurement of metabolic stability and metabolite identification of 7‐methoxymethylthiazolo[3,2‐a]pyrimidin‐5‐one derivatives in human liver microsomes using liquid chromatography/ion‐trap mass spectrometry
Authors: Kantharaj E. , Ehmer Peter B. , Tuytelaars An , Vlaslaer Anne Van , Mackie Claire , Gilissen Ron A. H. J. 
Published: March 2005

AbstractA liquid chromatography/mass spectrometry (LC/MS) method using an atmospheric pressure chemical ionisation source was used to measure the metabolic stability and metabolite identification of 7‐methoxymethylthiazolo[3,2‐a]pyrimidin‐5‐one derivative (1) in human liver microsomes. After 15 min incubation with human liver microsomes, compound 1 exhibited metabolic turnover of 44%. Data‐dependent tandem mass spectrometry (MS/MS) scanning was used to generate product ion spectra from the protonated ions of the compound and its metabolites. An unusual metabolite at m/z 407 corresponding to the [M–24+H]+ ion was identified for compound 1. Interestingly, the formation of the [M–24+H]+ ion was not observed in the analogues wherein the fused thieno double bond was substituted (2) and the thieno group replaced by a fused benzo derivative (3). Compounds 2 and 3 exhibited metabolic turnovers of 24 and 30%, yielding oxidative metabolites corresponding to [M+16] and [M+32]+, respectively. Based on these facts the mechanism for [M–24]+ formation in compound 1 through an initial epoxide formation on the double bond of the fused thieno ring followed by hydrolytic ring opening and deacylation is envisaged. Copyright © 2005 John Wiley & Sons, Ltd.
Detection of Microbial DNA in the Blood of Surgical Patients for Diagnosing Bacterial Translocation
Authors: Ono Satoshi , Tsujimoto Hironori , Yamauchi Akira , Hiraki Shuichi , Takayama Eiji , Mochizuki Hidetaka 
Published: March 2005

AbstractBacterial translocation sometimes occurs in patients during surgical stress and is associated with an increased incidence of septic morbidity. However, no reliable method has been established for diagnosing bacterial translocation in humans. Identification of minute quantities of microbial‐specific DNA has been made possible using polymerase chain reaction (PCR) techniques. The aims of this study were to determine the prevalence of bacterial translocation in patients with surgical stress using PCR techniques and to evaluate the usefulness of blood PCR techniques for diagnosing bacterial translocation. DNA was extracted from the blood of 52 surgical patients (24 elective major surgery patients and 28 septic patients) and 10 healthy controls. PCR techniques were used to amplify genes from Escherichia coli, Bacteroides fragilis, a region of 16S ribosomal RNA found in many gram‐positive and gram‐negative bacteria, and Candida albicans. Bacterial and Candida albicans DNA were not detected in healthy volunteers. Enteric bacterial DNA was detected in patients with hepatic lobectomy, and Candida albicans DNA was detected in patients with esophagectomy on the first postoperative day. Enteric bacterial and Candida albicans DNA were detected in septic patients with findings diagnostic of bacterial translocation, such as small bowel obstruction, ulcerative colitis, or supramesenteric arterial occlusion or in those who had undergone chemotherapy for advanced colon cancer. However, none of the patients were positive by the blood culture technique. The PCR method is more sensitive than blood cultures for detecting bacterial components in the blood of septic patients and is a valuable tool for verifying bacterial translocation in patients who have undergone hepatic lobectomy or esophagectomy. It is also valuable in septic patients who do not have a defined focus of infection.
Mid‐domain models as predictors of species diversity patterns: bathymetric diversity gradients in the deep sea
Authors: McClain Craig R. , Etter Ron J. 
Published: March 2005

Geometric constraints represent a class of null models that describe how species diversity may vary between hard boundaries that limit geographic distributions. Recent studies have suggested that a number of large scale biogeographic patterns of diversity (e.g. latitude, altitude, depth) may reflect boundary constraints. However, few studies have rigorously tested the degree to which mid‐domain null predictions match empirical patterns or how sensitive the null models are to various assumptions. We explore how variation in the assumptions of these models alter null depth ranges and consequently bathymetric variation in diversity, and test the extent to which bathymetric patterns of species diversity in deep sea gastropods, bivalves, and polychaetes match null predictions based on geometric constraints.Range–size distributions and geographic patterns of diversity produced by these null models are sensitive to the relative position of the hard boundaries, the specific algorithms used to generate range sizes, and whether species are continuously or patchily distributed between range end points. How well empirical patterns support null expectations is highly dependent on these assumptions. Bathymetric patterns of species diversity for gastropods, bivalves and polychaetes differ substantially from null expectations suggesting that geometric constraints do not account for diversity–depth patterns in the deep sea benthos.
Norfloxacin decreases bacterial adherence of quinolone‐resistant strains of Escherichia coli isolated from patients with cirrhosis
Authors: Gascón I. , Pascual S. , Plazas J. , Sánchez J. , Francés R. , Más P. , Zapater P. , Pérez‐Mateo M. , Such J. 
Published: March 2005

SummaryBackground:  Long‐term administration of norfloxacin is recommended for secondary prophylaxis of spontaneous bacterial peritonitis in cirrhosis, but it may be associated with the development of quinolone‐resistant bacteria in stools. However, these bacteria rarely cause infections.Aim:  To assess bacterial adherence of either quinolone‐sensitive or ‐resistant Escherichia coli obtained from stools of cirrhotic patients, as one of the main virulence factors, and its variations when sub‐minimum inhibitory concentration of norfloxacin were added to the medium.Methods:  E. coli strains were co‐cultured with oral epithelial cells obtained from patients in presence/absence of norfloxacin. Bacterial adherence was measured as percentage of cells exhibiting positive adherence and the number of bacteria attached to epithelial cells.Results:  37 sensitive and 22 resistant E. coli strains were studied. Bacterial adherence was similar in both series (78% vs. 81%, P = N.S.), and these percentages were similarly and significantly reduced when subminimum inhibitory concentration of norfloxacin was added to the culture medium (P < 0.001).Conclusions:  Bacterial adherence of E. coli obtained from patients with cirrhosis is unrelated to the sensitivity/resistance to quinolones, and is similarly reduced in both cases when subminimum inhibitory concentration of norfloxacin is added to the medium.
A randomized comparative study of esomeprazole 40 mg versus pantoprazole 40 mg for healing erosive oesophagitis: the EXPO study
Authors: Labenz J. , Armstrong D. , Lauritsen K. , Katelaris P. , Schmidt S. , Schütze K. , Wallner G. , Juergens H. , Preiksaitis H. , Keeling N. , Nauclér E. , Eklund S. 
Published: March 2005

SummaryAim:  To assess the efficacy of the 8‐week therapy with esomeprazole 40 mg vs. pantoprazole 40 mg for healing erosive oesophagitis (EE) as part of a management study.Methods:  Patients had a history of gastro‐oesophageal reflux disease symptoms (≥6 months) and had suffered heartburn on at least 4 of the 7 days preceding enrolment. Endoscopies were performed to grade EE severity using the Los Angeles (LA) classification system at baseline, 4 and 8 weeks (if unhealed at 4 weeks). Heartburn severity was recorded by patients on diary cards. The primary end point was healing of EE by week 8 of treatment.Results:  Of 3170 patients randomized, the intent‐to‐treat population consisted of 3151 patients (63% male, mean age: 50.6 years, 27%Helicobacter pylori‐positive). Esomeprazole 40 mg healed a significantly greater proportion of EE patients than pantoprazole 40 mg at both 4 weeks (life table estimates: esomeprazole 81%, pantoprazole 75%, P < 0.001) and 8 weeks (life table estimates: esomeprazole 96%, pantoprazole 92%, P < 0.001). The median time to reach sustained heartburn resolution was 6 days in patients receiving esomeprazole and 8 days with pantoprazole (P < 0.001).Conclusion:  Esomeprazole 40 mg is more effective than pantoprazole 40 mg for healing EE and providing resolution of associated heartburn.