bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the ability of multiphase continuum models to predict core‐annulus flow
Authors: Benyahia Sofiane , Syamlal Madhava , O'Brien Thomas J.
Published: August 2007

We use the well established core‐annulus flow regime as a numerical benchmark to evaluate the sensitivity of gas–solids continuum models and boundary conditions to model formalisms and parameters. By using transient, 1D, grid‐independent numerical solutions, we avoid the use of speculative closure terms and show that the kinetic theory of granular flow (KTGF) is sufficient to model core‐annulus regime. That regime arises in the time‐average solution as a consequence of the fluctuating motion of regions with high solids concentration. These fluctuations are most sensitive to the gravitational acceleration (g) and granular energy dissipation terms. The fluctuation frequency is α
$ \sqrt g $. The effect of fluctuations is so dominant that decreasing the restitution coefficient (KTGF parameter) actually increases the average granular temperature. The wall boundary conditions for solids momentum and granular energy equations dictate the core‐annulus flow regime. They must cause a net dissipation of granular energy at the wall for predicting that regime. © 2007 American Institute of Chemical Engineers AIChE J, 2007
A preliminary study of food transfer in sichuan snub‐nosed monkeys (Rhinopithecus roxellana)
Authors: Zhang Zhen , Su Yanjie , Chan Raymond C. K. , Reimann Giselle
Published: August 2007

Food transfer happens regularly in a few nonhuman primates species that are also characterized by remarkable social tolerance. Sichuan snub‐nosed monkeys (Rhinopithecus roxellana), or golden monkeys, which exhibit high social tolerance in their social relationships are thus of interest to see whether tolerance would extend to food transfer. In this study, branch feeding activity was observed in a semi‐captive group of Sichuan snub‐nosed monkeys, which consisted of 10 subjects that included a one‐male unit (OMU) and an all‐male unit (AMU). We recorded 1,275 food interactions over 27 days, and 892 instances of food transfer. The most commonly observed types of food transfer behavior were co‐feeding (62.1%) and relaxed claim (22.8%). Of 892 food transfers, 756 (84.8%) took place in the OMU, most of which were among adults (34.7%) and among juveniles (42.1%). The transfer success rate was high in both the cases (87.9% for adults and 78.9% for juveniles). Food transfer in the AMU took place less often than that among adults in the OMU though with similar high transfer success. Food transfer between the OMU and AMU was limited to juvenile males from the OMU and adults from the AMU. These results provide the first evidence of food transfer in golden monkeys and suggest that tolerant social relationships in golden monkeys make transfer possible. Am. J. Primatol. 70:148–152, 2008. © 2007 Wiley‐Liss, Inc.
Effects of magnetic field on the antioxidant defense system of recirculation‐cultured Chlorella vulgaris
Authors: Wang Hai‐Ying , Zeng Xiao‐Bo , Guo Si‐Yuan , Li Zong‐Tao
Published: August 2007

Little is known about the influence of magnetic fields (MF) on growth of microalgae such as Chlorella vulgaris, which has been consumed as health food for various nutritional and pharmacological effects. This preliminary study investigated whether static MF can modulate the antioxidant system in C. vulgaris by exposing the cells to static MF generated by dual yoke electromagnets with magnetic flux density of 10–50 mT for 12 h. After exposure to 10–35 mT for 12 h, the activity of superoxide dismutases and peroxidase increased significantly compared to control cells. However, a remarkable increase of catalase activity occurred at 45 and 50 mT. The lipid peroxidation of algae cells determined by production of thiobarbituric acid‐reactive substances was much increased when exposed to 35, 45, and 50 mT of MF. The scavenging ability of 2,2‐diphenyl‐1‐picrylhydrazyl radical was decreased markedly while there was no variation of total carotenoids content in C. vulgaris cells. Assay of specific growth rate in 72 h cultivation after MF exposure was also conducted. In groups after exposure to 10–35 mT of MF, specific growth rate was significantly increased. These results suggest that 10–35 mT of static MF exposure could promote the growth of C. vulgaris and regulate its antioxidant defense system to protect cells efficiently, which could possibly enhance the growth of C. vulgaris in industrialized cultivation by MF. Bioelectromagnetics 29:39–46, 2008. © 2007 Wiley‐Liss, Inc.
Optical Nanosensor Design with Uniform Pore Geometry and Large Particle Morphology
Authors: El‐Safty Sherif A. , Ismail Adel A. , Matsunaga Hideyuki , Mizukami Fujio
Published: August 2007

Appropriate design of nanosensors for optically selective, sensitive sensing systems is needed for naked‐eye detection of pollutants for environmental cleanup of toxic heavy‐metal ions. Mesostructured materials with two‐ or three‐dimensional (2D or 3D) geometries and large particle morphologies show promise as probe carriers, and can therefore be used to reproducibly fabricate uniformly packed nanosensors. This is the first report on the effects of significant key properties of the mesostructured carriers, such as morphology, geometry, and pore shape, on the functionality of optical nanosensor designs. Such mesostructured sensors with superior physical characteristics can be used as components in sensing systems with excellent stability and sensitivity, and with rapid detection response. The nanosensor design can enhance the selectivity even at low concentrations of the pollutant target ions (nanomolar level). Among the nanosensors developed here, the large pore‐surface grains of highly ordered 3D monoliths (HOM) exhibited a high adsorption capability of the Pyrogallol Red probe and high accessibility to analyte ion transport, leading to possible naked‐eye detection of SbIII ions at concentrations as low as 10−9 mol dm−3 and at a wide detection range of 0.5 ppb to 3 ppm. A key finding in our study was that our mesostructured nanosensor designs retained highly efficient sensitivity without a significant increase in kinetic hindrance, despite the slight decrease of the specific activity of the electron acceptor/donor strength of the probe functional group after several regeneration/reuse cycles. The results, in general, indicate that large‐scale reversibility of optical nanosensors is feasible in such metal‐ion sensing systems.
Ring Opening of the Cyclobutane in a Thymine Dimer Radical Anion
Authors: Chatgilialoglu Chryssostomos , Guerra Maurizio , Kaloudis Panagiotis , Houée‐Lévin Chantal , Marignier Jean‐Louis , Swaminathan Vijay N. , Carell Thomas
Published: August 2007

The reactions of hydrated electrons (eaq−) with thymine dimer 2 and thymidine have been investigated by radiolytic methods coupled with product studies, and addressed computationally by means of BB1K‐HMDFT calculations. Pulse radiolysis revealed that one‐electron reduction of the thymine dimer 2 affords the radical anion of thymidine (5) with t1/2<35 ns. Indeed, the theoretical study suggests that radical anion 3, in which the spin density and charge distribution are located in both thymine rings, undergoes a fast partially ionic splitting of the cyclobutane with a half‐life of a few ps. This model fits with the in vivo observation of thymine dimer repair in DNA by photolyase. γ‐Radiolysis of thymine dimer 2 demonstrates that the one‐electron reduction and the subsequent cleavage of the cyclobutane ring does not proceed by means of a radical chain mechanism, that is, in this model reaction the T−. is unable to transfer an electron to the thymine dimer 2.
Functional Classification of Protein Kinase Binding Sites Using Cavbase
Authors: Kuhn Daniel , Weskamp Nils , Hüllermeier Eyke , Klebe Gerhard
Published: August 2007

Increasingly, drug‐discovery processes focus on complete gene families. Tools for analyzing similarities and differences across protein families are important for the understanding of key functional features of proteins. Herein we present a method for classifying protein families on the basis of the properties of their active sites. We have developed Cavbase, a method for describing and comparing protein binding pockets, and show its application to the functional classification of the binding pockets of the protein family of protein kinases. A diverse set of kinase cavities is mutually compared and analyzed in terms of recurring functional recognition patterns in the active sites. We are able to propose a relevant classification based on the binding motifs in the active sites. The obtained classification provides a novel perspective on functional properties across protein space. The classification of the MAP and the c‐Abl kinases is analyzed in detail, showing a clear separation of the respective kinase subfamilies. Remarkable cross‐relations among protein kinases are detected, in contrast to sequence‐based classifications, which are not able to detect these relations. Furthermore, our classification is able to highlight features important in the optimization of protein kinase inhibitors. Using small‐molecule inhibition data we could rationalize cross‐reactivities between unrelated kinases which become apparent in the structural comparison of their binding sites. This procedure helps in the identification of other possible kinase targets that behave similarly in “binding pocket space” to the kinase under consideration.
Assessing symptom burden using the M. D. Anderson symptom inventory in patients with chemotherapy‐induced anemia
Authors: Gabrilove Janice L. , Perez Edith A. , Tomita Dianne K. , Rossi Greg , Cleeland Charles S.
Published: August 2007

BACKGROUND.

Patients with cancer who are receiving chemotherapy often experience chemotherapy‐induced anemia (CIA), which is associated with symptoms that reduce quality of life. The M. D. Anderson Symptom Inventory (MDASI) is a brief, self‐rating assessment scale that measures the severity of core symptoms and symptom interference with function. The current study used the MDASI to prospectively assess the correlation between hemoglobin and self‐perceived cancer‐related symptoms in a large patient population with CIA who were receiving darbepoetin‐α at a dose of 200 μg every 2 weeks.

METHODS.

Eligible patients enrolled in this multicenter, open‐label study were age ≥18 years, had a nonmyeloid malignancy, were receiving multicycle chemotherapy, and were anemic (hemoglobin ≤11 g/dL). Hemoglobin was measured every 2 weeks; the MDASI was administered weekly. For hemoglobin‐based endpoints, patients were stratified by baseline hemoglobin (< 10 g/dL or ≥10 g/dL).

RESULTS.

Of 2422 enrolled patients, 2401 received ≥1 dose of darbepoetin‐α. Eighty percent of patients (95% confidence limit, 78–82 patients) achieved target hemoglobin levels (≥11 g/dL) during the study. Patients with a baseline hemoglobin < 10 g/dL had a greater increase in hemoglobin, took longer to achieve the target hemoglobin, and received more red blood cell transfusions than patients with a baseline hemoglobin ≥10 g/dL. The percentage of patients with moderate to severe MDASI scores (≥5 points) for fatigue, distress, loss of appetite, disturbed sleep, and interference with function was reduced during the study. Improvement in symptom burden was associated with an increase in hemoglobin concentration.

CONCLUSIONS.

Treatment with darbepoetin‐α at a dose of 200 μg every 2 weeks is associated with improvement in symptom burden as measured by the MDASI, a simple tool that may improve symptom management for cancer patients with CIA. Cancer 2007. © 2007 American Cancer Society.
Expression of granulocyte‐colony‐stimulating factor and its receptor in human Ewing sarcoma cells and patient tumor specimens
Authors: Morales‐Arias Jaime , Meyers Paul A. , Bolontrade Marcela F. , Rodriguez Nidra , Zhou Zhichao , Reddy Krishna , Chou Alexander J. , Koshkina Nadezhda V. , Kleinerman Eugenie S.
Published: August 2007

BACKGROUND.

Ewing sarcoma (ES) is a highly vascular malignancy. It has been demonstrated that both angiogenesis and vasculogenesis contribute to the growth of ES tumors. Granulocyte‐colony‐stimulating factor (G‐CSF), a cytokine known to stimulate bone marrow (BM) stem cell production and angiogenesis, is routinely administered to ES patients after chemotherapy. Whether ES cells and patient tumor samples express G‐CSF and its receptor (G‐CSFR) and whether treatment with this factor enhances tumor growth was examined.

METHODS.

Human ES cell lines were analyzed for expression of G‐CSF and G‐CSFR in vitro and in vivo. Sixty‐eight paraffin‐embedded and 15 frozen tumor specimens from patients with ES were also evaluated for the presence of G‐CSF and G‐CSFR. The in vivo effect of G‐CSF on angiogenesis and BM cell migration was determined. Using a TC/7‐1 human ES mouse model, the effect of G‐CSF administration on ES tumors was investigated.

RESULTS.

G‐CSF and G‐CSFR protein and RNA expression was identified in all ES cell lines and patient samples analyzed. In addition, G‐CSF was found to stimulate angiogenesis and BM cell migration in vivo. Tumor growth was found to be significantly increased in mice treated with G‐CSF. The average tumor volume for the group treated with G‐CSF was 1218 mm3 compared with 577 mm3 for the control group (P = .006).

CONCLUSIONS.

The findings that ES cells and patient tumors expressed both G‐CSF and its receptor in vitro and in vivo and that the administration of G‐CSF promoted tumor growth in vivo suggest that the potential consequences of G‐CSF administration should be investigated further. Cancer 2007. © 2007 American Cancer Society.
Pramlintide reduced markers of oxidative stress in the postprandial period in patients with type 2 diabetes
Authors: Ceriello Antonio , Lush Cameron W. , Darsow Tamara , Piconi Ludovica , Corgnali Maddelena , Nanayakkara Nuwan , Frias Juan P. , Maggs David
Published: August 2007

Background

The production of oxidative stress as a result of postprandial hyperglycaemia is now recognized as an important contributing factor in the development of diabetes complications. The objective of this study was to examine the effects of pramlintide on plasma concentrations of glucose and several markers of oxidative stress in patients with type 2 diabetes following a standardized meal.

Methods

This was a randomized, single‐blind, placebo‐controlled, crossover study conducted at two clinical research centres in the United States. A total of 19 subjects (9 men and 10 women) with type 2 diabetes using mealtime insulin participated in the study. Pramlintide (120 µg), or placebo, and rapid‐acting mealtime insulin were administered prior to a standardized meal on two separate study days. Plasma concentrations of glucose, nitrotyrosine (NT), oxidized‐LDL cholesterol (OxLDL‐C), and total radical trapping parameter (TRAP) were assessed during the 4‐h postprandial period.

Results

Compared to placebo, pramlintide treatment reduced postprandial excursions of glucose, NT, and OxLDL‐C and protected TRAP from consumption. Correlation analysis revealed positive associations between placebo‐corrected glucose incremental AUC0–4h and both NT and OxLDL‐C and a negative association between placebo‐corrected glucose incremental AUC0–4h and TRAP.

Conclusions

The reduction in postprandial glucose excursions achieved with addition of pramlintide to rapid‐acting insulin in type 2 diabetes was associated with a reduction in postprandial markers of oxidative stress. Copyright © 2007 John Wiley & Sons, Ltd.
Circulating advanced glycation end products (AGEs) and soluble form of receptor for AGEs (sRAGE) are independent determinants of serum monocyte chemoattractant protein‐1 (MCP‐1) levels in patients with type 2 diabetes
Authors: Nakamura Kazuo , Yamagishi Sho‐ichi , Adachi Hisashi , Matsui Takanori , Kurita‐Nakamura Yayoi , Takeuchi Masayoshi , Inoue Hiroyoshi , Imaizumi Tsutomu
Published: August 2007

Background

Atherosclerosis is an inflammatory disease. Monocyte chemoattractant protein‐1 (MCP‐1) is an essential chemokine responsible for the recruitment of monocytes to inflammatory lesions in the vasculature, an initial step of atherosclerosis. Since serum levels of MCP‐1 are higher in patients with type 2 diabetes, inhibition of MCP‐1 may be a novel therapeutic target for prevention of accelerated atherosclerosis in diabetes. However, little is known about the regulation and determinants of serum MCP‐1 levels in patients with diabetes. In this study, we examined the determinants of serum MCP‐1 levels in type 2 diabetic patients.

Methods

Eighty‐six consecutive outpatients with type 2 diabetes (36 male and 50 female; mean age 68.4 ± 9.6) underwent a complete history and physical examination, determination of blood chemistries, MCP‐1, tumour necrosis factor‐α, adiponectin, advanced glycation end products (AGEs), and soluble form of receptor for AGEs (sRAGE). We examined the association between MCP‐1 levels and those in anthropometric, metabolic and inflammatory variables in these subjects.

Results

Univariate regression analysis showed that serum levels of MCP‐1 were positively associated with AGEs (r = 0.386, p < 0.001) and sRAGE (r = 0.315, p < 0.001). After adjusting for age and sex, AGEs (p < 0.001) and sRAGE (p < 0.05) still remained significant.

Conclusion

The results demonstrate for the first time that circulating levels of AGEs and sRAGE are independent determinants of serum MCP‐1 levels in patients with type 2 diabetes. Our present observations suggest the AGEs‐RAGE system may be mainly involved in the elevation of MCP‐1 in type 2 diabetic patients. Copyright © 2007 John Wiley & Sons, Ltd.
Diastereoselective 1,3‐Dipolar Cycloaddition Reactions between Azomethine Ylides and Chiral Acrylates Derived from Methyl (S)‐ and (R)‐Lactate – Synthesis of Hepatitis C Virus RNA‐Dependent RNA Polymerase Inhibitors
Authors: Nájera Carmen , de Gracia Retamosa M. , Sansano José M. , de Cózar Abel , Cossío Fernando P.
Published: August 2007

Highly endo‐diastereoselective 1,3‐dipolar cycloadditions between acrylates derived from methyl (R)‐ and (S)‐lactate, as chiral dipolarophiles, and azomethine ylides derived from glycine and α‐substituted amino acids are described. The origins of the observed excellent stereocontrol are interpreted on the basis of computational studies on model systems. This methodology was successfully employed for the first asymmetric synthesis of both enantiomers, as well as of its racemic form, of a biologically active pyrrolidine (hepatitis C virus inhibitor) incorporating a leucine residue and a 2‐thienyl group. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Predictive factors for complications in elderly patients who underwent head and neck oncologic surgery
Authors: Sanabria Alvaro , Carvalho André L. , Melo Rosana L. , Magrin José , Ikeda Mauro K. , Vartanian José G. , Kowalski Luiz P.
Published: August 2007

Background.

Postoperative complications are relevant outcomes in patients with head and neck tumor who have undergone surgery. Few trials have assessed predictive factors in older patients. We assessed the predictive effect of preoperative clinical factors on postoperative complications.

Methods.

We conducted a cohort study with 242 patients older than 70 years with head and neck cancer who underwent surgery. Logistic regression identified predictive factors for postoperative complications. Significant variables were used to build a predictive index.

Results.

Comorbidities were present in 87.6% of patients, and 56.6% had some type of complication (44.6% local and 28.5% systemic). Male sex, bilateral neck dissection, presence of 2 or more comorbidities, reconstruction, and clinical stage IV were associated with postoperative complications. The predictive index showed a receiver operating characteristics curve (ROC) area of 0.69.

Conclusion.

It is possible to predict postoperative complications in older patients with head and neck tumors who underwent oncologic surgery using clinical preoperative variables. © 2007 Wiley Periodicals, Inc. Head Neck, 2008
Interpretability of PET/CT imaging in head and neck cancer patients following composite mandibular resection and osteocutaneous free flap reconstruction
Authors: Oliver Christopher , Muthukrishnan Ashok , Mountz James , Deeb Erin , Johnson Jonas , Deleyiannis Frederic
Published: August 2007

Background.

We investigated positron emission tomography (PET)/CT scanning following segmental resections and osteocutaneous free‐flap reconstruction. The interpretability of PET/CT imaging with healing osteotomies and reconstruction hardware was analyzed.

Methods.

Patient scans within 18 months of surgery were interpreted for malignancy. Interpretations were compared with clinical data to determine sensitivity/specificity. Standardized uptake values (SUVs) were determined for bony controls, osteotomies, and tumors and were analyzed using paired t test.

Results

Fifteen scans were visually interpreted, 13 underwent SUV analysis. Reconstruction hardware did not interfere with interpretability. Sensitivity and specificity were 88% and 86%, respectively. Osteotomy sites averaged 25% higher SUVs compared with bony controls (vs sternum p = .003, vs mandible p = .008). Tumor SUVs were higher than osteotomies (p = .023) and controls (vs sternum p = .013, vs mandible p = .025).

Conclusion.

Although osteotomies were characterized by an increased fluorodeoxyglucose signal, scan interpretability was unimpaired. Our study suggests that PET/CT imaging can be utilized to survey free‐flap patients at acceptable levels of sensitivity/specificity. © 2007 Wiley Periodicals, Inc. Head Neck, 2008
Mutations in the MPV17 gene are responsible for rapidly progressive liver failure in infancy
Authors: Wong Lee-Jun C. , Brunetti-Pierri Nicola , Zhang Qing , Yazigi Nada , Bove Kevin E. , Dahms Beverly B. , Puchowicz Michelle A. , Gonzalez-Gomez Ignacio , Schmitt Eric S. , Truong Cavatina K. , Hoppel Charles L. , Chou Ping-Chieh , Wang Jing , Baldwin Erin E. , Adams Darius , Leslie Nancy , Boles Richard G. , Kerr Douglas S. , Craigen William J.
Published: August 2007

MPV17 is a mitochondrial inner membrane protein of unknown function recently recognized as responsible for a mitochondrial DNA depletion syndrome. The aim of this study is to delineate the specific clinical, pathological, biochemical, and molecular features associated with mitochondrial DNA depletion due to

MPV17

gene mutations. We report 4 cases from 3 ethnically diverse families with

MPV17

mutations. Importantly, 2 of these cases presented with isolated liver failure during infancy without notable neurologic dysfunction.

Conclusion:

We therefore propose that mutations in the

MPV17

gene be considered in the course of evaluating the molecular etiology for isolated, rapidly progressive infantile hepatic failure. (HEPATOLOGY 2007.)
Semi‐nonparametric competing risks analysis of recidivism
Authors: Bierens Herman J. , Carvalho Jose R.
Published: August 2007

In this paper we specify a semi‐nonparametric competing risks (SNP‐CR) model of recidivism, for misdemeanors and felonies. The model is a bivariate mixed proportional hazard model with Weibull baseline hazards and common unobserved heterogeneity. The distribution of the latter is modeled semi‐nonparametrically, using orthonormal Legendre polynomials on the unit interval, and integrated out to make the two durations dependent, conditional on the covariates. The SNP‐CR model involved corresponds to a Logit model for felony arrest; hence the validity of the SNP‐CR model can be tested by testing the validity of the implied Logit model. The latter will be done by using the integrated conditional moment (ICM) test. In the first instance we have estimated and tested two versions of the SNP‐CR model, without and with fixed state effects. However, the ICM test rejects these models. Therefore, we have estimated and tested the model for each state separately. These state models are not rejected by the ICM test. Indeed, the estimation results vary substantially per state. Copyright © 2007 John Wiley & Sons, Ltd.
Biovalidation of an SPE‐HPLC‐UV‐fluorescence method for the determination of Valsartan and its metabolite valeryl‐4‐hydroxy‐valsartan in human plasma
Authors: Iriarte Gorka , Ferreirós Nerea , Ibarrondo Izaskun , Alonso Rosa Maria , Itxaso Maguregui Miren , Jiménez Rosa Maria
Published: August 2007

A simple and fast method for the simultaneous determination of the antihypertensive drug Valsartan and its metabolite in human plasma has been validated. The proposed method deals with SPE, followed by an HPLC separation coupled with fluorimetric and photometric detection. The optimization of the SPE‐HPLC method was achieved by an experimental design. The separation was performed on an RP C18 Atlantis 100 mm×3.9 mm column. The mobile phase consisted of a mixture of ACN 0.025% TFA and phosphate buffer (5 mM, pH = 2.5) 0.025% TFA and was delivered in gradient mode at a flow rate of 1.30 mL/min. The eluent was monitored with a fluorescence detector at 234 and 378 nm excitation and emission wavelengths, respectively, and at 254 nm using a photometric detector. The full analytical validation was performed according to the Food and Drug Administration (FDA) ‘guidance for industry: bioanalytical method validation’ and the recoveries obtained for Valsartan and its metabolite ranged from 94.6 to 108.8%. The validated method was successfully applied to 12 plasma samples obtained from patients under antihypertensive treatment with Valsartan.
Resolution of β‐amino acids on a high performance liquid chromatographic doubly tethered chiral stationary phase containing N–CH3 amide linkage based on (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid
Authors: Hyun Myung Ho , Song Yanci , Cho Yoon Jae , Choi Hee Jung
Published: August 2007

A doubly tethered chiral stationary phase (CSP) containing N–CH3 amide linkage based on (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid was applied to the resolution of various β‐amino acids. The chiral recognition behaviors for the resolution of β‐amino acids on the doubly tethered CSP were consistent with those on the corresponding singly tethered CSP while the chiral recognition ability of the doubly tethered CSP was generally greater in terms of both the separation (α) and the resolution factors (RS) than that of the corresponding singly tethered CSP. From these results, it was concluded that attaching the second tethering group to silica gel through a carbon atom of the first tethering group of the CSP improves the chiral recognition ability for the resolution of β‐amino acids without any change in the chiral recognition mode. The retention factors (k1) on the doubly tethered CSP were larger than those on the corresponding singly tethered CSP and these retention factors were found to be controllable with the variation of the type and the content of the organic and/or acidic modifier in the aqueous mobile phase without significant change in the separation and the resolution factors.
Electrical doping is paving the way for the implementation of OLEDs in consumer electronics
Authors: Rothe C.
Published: August 2007

The great potential of organic light‐emitting diodes (OLEDs) to replace current display and lighting technologies is no longer questioned. Nevertheless, before large‐scale production can commence, considerable advances in the OLED technology are still necessary to satisfy the corresponding challenging requirements and to be competitive with firmly established alternative technologies. In this context, significant progress in diode performance, lifetime and stability is achieved by employing electrically doped charge‐transport layers. Thus, the so‐called PIN technology allows for an early, successful implementation of OLEDs in consumer applications.
Macromol. Rapid Commun. 16/2007
Authors: Wang Huiping , Lu Ping , Wang Baoling , Qiu Song , Liu Meirong , Hanif Muddasir , Cheng Gang , Liu Shiyong , Ma Yuguang
Published: August 2007

Cover: A cationic water‐soluble polyfluorene with excellent solubility and high PL quantum yield in water has been prepared. The high cationic density and appropriate side chain length of the polymer are the key factors to achieve such high water solubility. Further details can be found in the article by H. Wang, P. Lu, B. Wang, S. Qiu, M. Liu, M. Hanif, G. Cheng, S. Liu, and Y. Ma on page 1645.
Dielectric Properties of Hyperbranched Polyesteramide with Long Alkyl Chain End Groups
Authors: Elrehim Mona Abd , Said Shereen , Ghoneim Ahmed , Turky Gamal
Published: August 2007

Summary: Hyperbranched polyesteramides were prepared using phethalic anhydride (Ph An) or maleic anhydride (M An) as an A2 monomer and diethanol amine (DEA) as B′B2 monomer. Bulk condensation technique was used to synthesize polymers with both OH and modified polymers with long alkyl chain end groups. The prepared polymers were characterized using 1H‐NMR, FTIR and TGA. Solution viscosity for hyperbranched polyester amide with hydroxyl end groups was measured as well. Dielectric and electric properties of the modified samples were investigated over a range of frequency and temperatures. No relaxation peak is noticed in the dielectric spectrum ε(ν) at various temperatures. The illustration of the imaginary part of the electric modulus M″ versus frequency shows a peak which is shifted towards higher frequency in increasing temperature.
Hyperbranched Polymers in Cationic UV Curing
Authors: Sangermano M. , Amerio E. , Di Gianni A. , Priola A. , Pospiech D. , Voit B.
Published: August 2007

Summary: A wide range of hyperbranched polymers (HBP) was synthesized and investigated as additives in cationic photopolymerization of epoxy systems. The HBP were inserted into the polymeric network either by a copolymerization or through a chain transfer reaction involving the phenolic hydroxyl groups. By varying the type and concentration of HBP a modification of the bulk properties of photocured films was induced. An increase of toughness properties together with a flexibilization was obtained without affecting the processability and the viscosity of the photocurable mixture. In the presence of fluorine‐containing HBP, a surface modification was induced.
Cycloaddition Reactions and Dendritic Polymer Architectures – A Perfect Match
Authors: Voit Brigitte , Fleischmann Sven , Komber Hartmut , Scheel Arnulf , Stumpe Katrin
Published: August 2007

Summery: The potential of cycloaddition (CA) reactions for the synthesis of dendritic polymers is pointed out. The [4 + 2] Diels Alder cycloaddition as well as 1,3‐dipolar CA reactions including “click chemistry” are addressed, and the advantages of these reactions like high selectivity, thus high tolerance towards additional functionalities, high yields and synthesis under mild reaction conditions are highlighted. New perfectly branched dendrimers as well as hyperbranched polymers have been prepared and modified using the 1,3‐dipolar cycloaddition reaction of azines with alkynes. The 1,3‐dipolar CA reaction of bisazine with maleimides results in hyperbranched and thus, irregular and broadly distributed polymers though with a degree of branching of 100% due to special intermediate formation. The [4 + 2] Diels Alder cycloaddition was successfully applied for the synthesis of highly branched polyphenylene structures using the AB2 + AB and the A2 + B3 approach. CA reactions are also very suitable for highly efficient polymer analogous reactions and thus, they can also be used to prepare complex polymer architectures like dendronized polymers.
Amylose and Amylopectin Hybrid Materials via Enzymatic Pathways
Authors: van der Vlist Jeroen , Loos Katja
Published: August 2007

Summary: Oligo‐ and polysaccharides are important macromolecules in living systems, showing their multifunctional characteristics in the construction of cell walls, energy storage, cell recognition and their immune response.

Saccharides as organic raw materials can open new perspectives on the way to new biocompatible and biodegradable products which could help to overcome the problems resulting from the upcoming restrictions of petrochemical resources. Construction of well‐defined carbohydrate polymer backbones is very challenging as it is difficult to realize complete regio and stereo‐control of the glycosylating process. Most synthetic approaches are therefore based on the modification or degradation of naturally occurring polysaccharides resulting in less then perfect products. Enzymes have several remarkable catalytic properties compared with other types of catalysts in terms of their selectivity, high catalytic activity, lack of undesirable side reactions and operation under mild conditions. A biocatalytic pathway to synthesize saccharides is therefore very attractive as it results in well‐defined polysaccharides avoiding the above drawbacks.

When biogenic polysaccharides are combined with synthetic macromolecules, surfaces etc. materials with new interesting properties arise and the processability of the designed hybrid materials is facilitated. Amylose and amylopectin hybrid materials can be synthesized via enzymatic polymerization routes utilizing transferases. This approach opens access to well‐defined hybrid structures bearing amylase or amylopectin moieties that cannot be synthesized by any other means.
Hard and Soft Capsules: From Branched Polymers to Controlled Release via Gels
Authors: Binder Wolfgang H. , Petraru Laura , Weinstabl Harald , Gloger Dietrich , Sachsenhofer Robert
Published: August 2007

Summary: Supramolecular gels, made from the combination of telechelic poly (ethyleneglycols) (PEG's) and trivalent poly(isobutylenes) with terminal matching hydrogen bonds were prepared and their rheological properties were investigated. Addition of poly(N‐isopropylacrylamide) as thermosensitive polymer was included into the gel‐capsules in amounts of 10 w%, producing gels with strongly thermally‐ responsive properties. Additionally, dansyl‐dyes with two different endgroups (either an hydrophobic endgroup or a multiple hydrogen bond) were encapsulated into the gels as mimicks for pharmaceutically active substances. Monitoring their diffusion by UV‐dependent measurements allowed to tune the diffusion and thus the release properties of the gel. The generated supramolecular gels will allow the selective encapsulation and triggered release of various pharmaceuticals and biologically active targets.
Synthesis of Novel Polymers with a Chiral 1,2‐Diamine Moiety by Polycondensation and their Application to Catalyst for Asymmetric Hydrogenation of Aromatic Ketones
Authors: Haraguchi Naoki , Prasad Nilesh anand , Uchiyama Takao , Itsuno Shinichi
Published: August 2007

Summary: Novel polymers with chiral 1,2‐diamine moiety were successfully synthesized by polycondensation of N‐Boc protected enantiopure 1,2‐diamine bearing two phenol groups (S,S)‐4, bisphenol derivatives, and dibromides, followed by deprotection of N‐Boc moiety. Hydrogenation of acetophenone was performed with use of polymeric catalyst system prepared from the polymer‐supported chiral 1,2‐diamine and RuCl2/(S)‐BINAP. The reaction proceeded smoothly even in 2‐propanol to give 1‐phenylethanol in quantitative yield with high level of enantioselectivity. Furthermore, various other aromatic ketones could be asymmetrically hydrogenated by the polymeric catalyst system.
Novel Approaches to Metallization of Cellulose by Reduction of Cellulose‐Incorporated Copper and Nickel Ions
Authors: Kotelnikova N. , Vainio U. , Pirkkalainen K. , Serimaa R.
Published: August 2007

Summary: Copper and nickel nanoparticles were synthesized in the insoluble microcrystalline cellulose support by reduction of metal ions with several reducers in various media resulting in cellulose‐metal nanocomposites. Wide‐angle X‐ray scattering results showed that supramolecular structure of cellulose did not change. Crystalline Cu2O and Cu0 nanoparticles were prepared with reducers NaBH4 and N2H4 · H2SO4, CuO nanoparticles – with cellulose itself as a reducer. Crystalline Ni0 nanoparticles were synthesized with N2H4 · 2HCl and NaBH4; Ni0 nanoparticles in amorphous form were prepared with KH2PO2 · H2O. SEM revealed large agglomerates of metal particles on the fibre surface. ASAXS and TEM have shown the nanoparticles to be in the range 5–55 nm.
“Grafting From” ‐Living Cationic Polymerization of Poly(isobutylene) from Silica‐Nanoparticle Surfaces
Authors: Zirbs Ronald , Binder Wolfgang , Gahleitner Markus , Machl Doris
Published: August 2007

Summary: This publication discusses the development of new methods for producing organic‐inorganic core‐shell‐nanoparticles (NP's) via a combination of “grafting‐from” techniques and living cationic polymerization reactions. Based on the surface initiated, quasiliving cationic polymerization of isobutylene, polymeric shells of polyisobutylene (PIB) were attached onto nanoparticles (silica NP's of different sizes, r = 12–40 nm) with a high degree of precision. “Grafting‐from” polymerization provides an ideal method to control the number of polymer chains per particle by means of the degree of initial derivatization and the length of the polymeric chains. The resulting nanocomposite materials were analyzed using DLS, TEM, GPC, TGA, DSC.
Ag Nanocomposite Particles: Preparation, Characterization and Application
Authors: Lu Y. , Yu M. , Drechsler M. , Ballauff M.
Published: August 2007

Summary Herein, we report that different core‐shell particles could be successfully used as the carrier systems for the deposition of silver nanoparticles. Firstly, thermosensitive core‐shell microgel particles have been used as the carrier system for the deposition of Ag nanoparticles, in which the core consists of poly (styrene) (PS) whereas the shell consists of poly (N‐isopropylacrylamide) (PNIPA) network cross‐linked by N, N′‐methylenebisacrylamide (BIS). Immersed in water the shell of these particles is swollen. Heating the suspension above 32 °C leads to a volume transition within the shell, which is followed by a marked shrinking of the network of the shell. Secondly, “nano‐tree” type polymer brush can be used as “nanoreactor” for the generation of silver nanoparticles also. This kind of carrier particles consists of a solid core of PS onto which bottlebrush chains synthesized by the macromonomer poly (ethylene glycol) methacrylate (PEGMA) are affixed by “grafting from” technique. Thirdly, silver nanoparticles can be in‐situ immobilized onto polystyrene (PS) core‐polyacrylic acid (PAA) polyelectrolyte brush particles by UV irradiation. Monodisperse Ag nanoparticles with diameter of 8.5 nm, 7.5 nm and 3 nm can be deposited into thermosensitive microgels, “nano‐tree” type polymer brushes and polyelectrolyte brush particles, respectively. Moreover, obtained silver nano‐composites show different catalytic activity for the catalytic reduction of p‐nitrophenol depending on the carrier system used for preparation.
Swelling of the Zwitterionic Copolymer Networks and Dehydration of their Hydrogels
Authors: Kamenova I. , Harrass M. , Lehmann B. , Friedrich K. , Ivanov I. , Georgiev G.
Published: August 2007

Summary: The polyelectrolyte and antipolyelectrolyte effects on the degree of swelling (Q) and dehydration activation energy (Ea) of homo‐ and copolymer single and double networks, consisting of monomer units with polyelectrolyte and antipolyelectrolyte association abilities are determined and compared. An original correlation between Q and Ea is outlined and explained.
Composite Particles: Design of Hybrid Materials on the Nano‐Scale
Authors: Hain Jessica , Pich Andrij , P. Adler Hans‐Jürgen
Published: August 2007

Summary: In the last decade there has been a steady increased interest in the techniques providing design of nano‐structured materials. It has been demonstrated that colloidal polymeric particles can be successfully used for the deposition of different functional nano‐materials. Due to their numerous attractive properties polymeric particles have been used as templates for the synthesis, storage and transportation of nanostructured materials. This contribution demonstrates the synthetic ways for the preparation of hybrid particles by effective control over the size, morphology and distribution of the non‐miscible phases. Developed methods allow design of the composite particles on the nanometer scale and opens new possibilities for the preparation of the materials with advanced properties. The synthesis, characterization and applications of hybrid particles are discussed in detail.
In‐Situ Formation of BHET/Titanium Compound Nanocomposite and its Catalysis for Polyester
Authors: Xin Guoying , Sun Bin , Wang Wei , Zhu Liping , Wu Wenhua , Zhu Meifang , Chen Yanmo , Adler Hans‐Jurgen P.
Published: August 2007

Summary: The tetrabutylorthotitanate (TBOT) was hydrolyzed by H2O produced during the esterification of pure terephthalic acid (PTA) and ethylene glycol (EG), and the bis(2‐hydroxyethyl) terephthalate (BHET)/titanium compound nanocomposite was in‐situ formed. The effect of TBOT on the esterification and its product property has been investigated. The results show that the butyl alcohol from the hydrolysis of TBOT is almost distilled out with H2O and there has no effect on the chemical structure of BHET caused by the introducing of TBOT. A kind of novel titanium compound is manufactured during the esterification under the existence of TBOT, which shows slice‐like morphology from SEM micrographs and special XRD pattern with new diffraction peaks between 2‐Θ = 6.9° and 10.2°. It is found that the BHET/titanium compound nanocomposite can act as the catalyst of polymerization of poly(ethylene terephthalate) (PET). The PET resins synthesized by in‐situ formed catalyst have almost the same physicochemical properties with the commerced resins and have good spinnability.
Preparation and Enantiospecific Binding of Chiral Polyelectrolyte Multilayers: AnIn‐SituATR‐FTIR Study
Authors: Ouyang Wuye , Appelhans Dietmar , Voit Brigitte , Muller Martin
Published: August 2007

Summary:Two chiral polyelectrolyte multilayers (PEM) composed of poly(L‐lysine) (PLL) and poly(vinylsulfate) (PVS) as well as poly(ethyleneimine‐maltose) (PEI‐m) and poly(vinylsulfate) and a nonchiral PEM composed of poly(ethyleneimine) (PEI) and poly(vinylsulfate) were deposited on a silica surface using the layer by layer method. For both PEM enantiospecific interaction towards one enantiomer of either L‐/D‐ glutamic acid (L‐/D‐GLU) or L‐/D‐ascorbic acid (L‐/D‐ASC), respectively, was checked under variation of the concentration. Both deposition and enantiospecific interaction were studied by attenuated total reflection Fourier transform (ATR‐FTIR) spectroscopy. Preliminary results show a significant enantiospecific preference of D‐ GLU over L‐GLU at PEM of PLL/PVS and of D‐ASC over L‐ASC at PEM of PEI‐m/PVS and no such preference for nonchiral PEM of PEI/PVS. PEM of PLL/PVS shows higher enantiospecifity with increasing L‐/D‐GLU concentration.
Early Stages of Interchange Reactions in Polymer Blends
Authors: Kudryavtsev Yaroslav V. , Chertovich Alexander V. , Guseva Darja V. , Litmanovich Arkady D.
Published: August 2007

Summary: Simple models are studied for better understanding of the early stages of interchange reactions in polymer blends. For a homogeneous blend of homopolymers A and B, parameters of copolymer AB formed at the reaction beginning are explicitly calculated. It is shown that the analysis of the copolymer composition can help to establish the prevailing interchange mechanism. For a bilayer blend of immiscible homopolymers A and B, the reactive compatibilization through interchange is studied by continual Monte Carlo modeling. The analysis of the local distribution in block length shows that the interdiffusion of blend components may start only after the formation of rather short copolymer blocks in the course of interchange.
Synthesis and Photopatterning of Fluorene Based Reactive Mesogens
Authors: Scheler Esther , Bauer Irene , Strohrigl Peter
Published: August 2007

Summary: In this paper we report the synthesis, characterisation and photopatterning of polydisperse fluorene oligomers. The oligomers were synthesised using the Yamamoto coupling. The molecular weights of the oligomers and as a consequence the nematic‐isotropic transition temperatures were tailored by an endcapping reaction. With the endcapping species we introduced reactive acrylate functionalities. Subsequent photocrosslinking through a test mask led to the formation of fluorescent microstructures with a resolution of 1 µm.
Influence of Reactive Compatibilization on the Melt Flow Properties and Morphology of Polyamide 6/Styrene‐Acrylonitrile Blends
Authors: Sailer Christian , Handge Ulrich Alexander
Published: August 2007

Summary: In this study, we investigate the influence of reactive compatibilization on the rheological properties of polyamide 6/styrene‐acrylonitrile (PA 6/SAN) blends in the melt. Linear viscoelastic shear oscillations, simple elongation to a large stretch ratio and subsequent recovery experiments were performed. The morphology of the blends was examined by atomic force microscopy. We prepared three PA 6/SAN blends with different composition ratios of PA 6 and SAN (70/30, 50/50, 30/70) and a constant concentration of the reactive agent. Our experiments revealed that reactive compatibilization significantly increases the complex modulus of PA 6/SAN blends at low frequencies. In particular, the data of the PA 6/SAN 50/50 blend and the PA 6/SAN 30/70 blend indicated that an elastic network between neighbouring PA 6 domains was formed. In simple elongation, the transient elongational viscosity of the blends exceeded the values of the single components. In recovery, the recovered stretch of all blends was larger than the recovered stretch of the pure components. The differences of the blend morphology and of the linear viscoelastic behaviour were qualitatively explained by the asymmetric properties of the reactively compatibilized interface.
Two Routes for Immobilization of a Hyperbranched OH‐Terminated Polyester on a Silicon Surface
Authors: Reichelt Senta , Jakisch Lothar , Simon Frank , Grundke Karina , Eichhorn Klaus‐Jochen , Voit Brigitte
Published: August 2007

Summary: Stable thin films of a hyperbranched aromatic‐aliphatic OH‐terminated polyester (POH) were prepared on silicon substrates. We report on grafting‐to processes using macromolecular (PGMA) and bifunctional low‐molecular weight coupling agents (BOX). An appropriate annealing procedure was developed for the covalent immobilization. The HBP films were characterized with spectroscopic ellipsometry, drop shape analysis (DSA), atomic force microscopy (AFM), X‐ray photoelectron spectroscopy (XPS) and electrokinetic measurements. The immobilized films have an uniform surface morphology and are slightly hydrophilic (θa = 79°). The grafting process did not influence the chemical composition and the surface properties, which is important for the further application as functional layers in aqueous media.
Infrared Spectra of Alkylphosphonic Acid Bound to Aluminium Surfaces
Authors: Luschtinetz Regina , Seifert Gotthard , Jaehne Evelin , Adler Hans‐Jurgen P.
Published: August 2007

Summary: The infrared absorption (IR) spectrum of alkyl phosphonic acid adsorbed on the α‐Al2O3 (0001) surface has been calculated by means of a density‐functional based tight‐binding method. Thereby mono‐dentate, bi‐dentate and tri‐dentate bonding of the acid to the surface have been considered. In addition, experimentally obtained Fourier Transform Infrared Spectra (FTIR) of octadecylphosphonic acid (ODPA) on the natural surface of aluminium have been included. The absence of the PO band in the experimental surface spectrum and in the calculated spectrum of the tridentate adsorption complexes showed that adsorption of (alkyl)phosphonic acids on aluminium favours tridentate bonding, where the acid is bound to the surface via three symmetric POAl bonds.