bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of various second‐dimension gradient types in comprehensive two‐dimensional liquid chromatography
Authors: Jandera Pavel , Hájek Tomáš , Česla Petr
Published: March 2010

Gradient elution provides significant improvement in peak capacity with respect to isocratic conditions. In the second dimension, gradients are limited to a short‐time period available for separation. Various types of second‐dimension gradients in comprehensive LC×LC are compared: (i) “full in fraction”, (ii) “segment in fraction” and (iii) “continuously shifting” gradients, applied in orthogonal LC×LC separations of phenolic acids and flavones on a polyethylene glycol column in the first dimension and two types of porous shell fused‐core C18 columns in the second dimension (Ascentis Express and Kinetex). The porous shell columns provide narrow bandwidths and fast second‐dimension separations at moderate operating pressure that allows important savings of the overall separation time in comprehensive LC×LC separations. The effects of the gradient type on the bandwidths, theoretical peak capacity, separation time and column pressure in the second dimension were investigated. The type of gradient program controls the range of lipophilicity of sample compounds that can be separated in the second‐dimension reversed‐phase time period. This range can be calibrated using alkylbenzene standards, to design the separation conditions for complete sample separation, avoiding harmful wrap around of non‐eluted compounds to the subsequent second‐dimension fractions.
Synthesis and isolation of added‐value milk fat derivatives using lipase‐catalyzed reactions and supercritical carbon dioxide
Authors: Lubary Marta , Hofland Gerard W. , ter Horst Joop H.
Published: March 2010

Lipase‐catalyzed reactions and supercritical technology are powerful tools that can be effectively combined for the modification and processing of fats. In addition, both are “green” technologies, which can produce high‐quality, food‐grade products without the need of additional solvents. We show two examples in which milk fat was used as raw material for the production of added‐value derivatives: short‐chain fatty acid ethyl esters, which are natural flavor agents; and a diacylglycerol‐based, potentially superior dietary fat. In both cases we applied a combination of lipases and supercritical carbon dioxide extraction for the synthesis and separation of products.
Restoration of motor inhibition through an abnormal premotor‐motor connection in dystonia
Authors: Huang Ying‐Zu , Rothwell John C. , Lu Chin‐Song , Wang JiunJie , Chen Rou‐Shayn
Published: March 2010

To clarify the rationale for using rTMS of dorsal premotor cortex (PMd) to treat dystonia, we examined how the motor system reacts to an inhibitory form of rTMS applied to the PMd in healthy subjects and in a group of patients with focal hand dystonia and DYT1 gene carriers. Continuous theta burst transcranial magnetic stimulation (cTBS) with 300 and 600 pulses (cTBS300 and cTBS600) was applied to PMd, and its after‐effects were quantified by measuring the amplitude of MEPs evoked by single pulse transcranial magnetic stimulation (TMS) over the primary motor cortex (M1), short interval intracortical inhibition/facilitation (SICI/ICF) within M1, the third phase of spinal reciprocal inhibition (RI), and writing tests. In addition, in DYT1 gene carriers, the effects of cTBS300 over M1 and PMd on MEPs were studied in separate experiments. In healthy subjects, cTBS300 and cTBS600 over PMd suppressed MEPs for 30 min or more and cTBS600 decreased SICI and RI. In contrast, neither form of cTBS over PMd had any significant effect on MEPs, while cTBS600 increased effectiveness of SICI and RI and improved writing in patients with writer's cramp. NMDYT1 had a normal response to cTBS300 over left PMd. We suggest that the reduced PMd to M1 interaction in dystonic patients is likely to be due to reduced excitability of PMd‐M1 connections. The possible therapeutic effects of premotor rTMS may therefore involve indirect effects of PMd on SICI and RI, which this study has shown can be normalised by cTBS. © 2010 Movement Disorder Society
LINGO1 polymorphisms are associated with essential tremor in Europeans
Authors: Thier Sandra , Lorenz Delia , Nothnagel Michael , Stevanin Giovanni , Dürr Alexandra , Nebel Almut , Schreiber Stefan , Kuhlenbäumer Gregor , Deuschl Günther , Klebe Stephan
Published: March 2010

Essential tremor (ET) is one of the most common movement disorders. Former association studies focussing on candidate genes in ET found a number of risk variants but most of them were not replicated. Recently, a genome‐wide association study revealed two intronic sequence variants in the LINGO1 gene associated with ET. Here, we have confirmed association between sequence variants in the LINGO1 gene and the ET phenotype in independent German and French ET samples. The odds ratios for the identified intronic markers rs8030859 (P = 1.0×10−4), rs9652490 (P = 9.1×10−4), and rs11856808 (P = 3.6×10−2) were 1.72 (CI 1.31‐2.26), 1.61 (CI 1.21‐2.14), and 1.30 (CI 1.02‐1.66), respectively, in our German sample. LINGO1 is an interesting candidate gene because it plays a key role in central nervous system biology, is selectively expressed in the nervous system, and is an inhibitor of oligodendrocyte differentiation and neuronal myelination. Our study gives further evidence that LINGO1 acts as a susceptibility gene for ET. © 2010 Movement Disorder Society
ATP13A2 mutations (PARK9) cause neurodegeneration with brain iron accumulation
Authors: Schneider Susanne A. , Paisan‐Ruiz Coro , Quinn Niall P. , Lees Andrew J. , Houlden Henry , Hardy John , Bhatia Kailash P.
Published: March 2010

Kufor Rakeb disease (KRD, PARK9) is an autosomal recessive extrapyramidal‐pyramidal syndrome with generalized brain atrophy due to ATP13A2 gene mutations. We report clinical details and investigational results focusing on radiological findings of a genetically‐proven KRD case. Clinically, there was early onset levodopa‐responsive dystonia‐parkinsonism with pyramidal signs and eye movement abnormalities. Brain MRI revealed generalized atrophy and putaminal and caudate iron accumulation bilaterally. Our findings add KRD to the group of syndromes of neurodegeneration with brain iron accumulation (NBIA). KRD should be considered in patients with dystonia‐parkinsonism with iron on brain imaging and we suggest classifying as NBIA type 3. © 2010 Movement Disorder Society
A new rating instrument to assess festination and freezing gait in Parkinsonian patients
Authors: Ziegler Kerstin , Schroeteler Frauke , Ceballos‐Baumann Andres O. , Fietzek Urban M.
Published: March 2010

Festination and freezing of gait (FOG) are sudden episodic inabilities to initiate or sustain locomotion mostly experienced during the later stages of Parkinson's disease (PD) or other higher‐level gait disorders. The aim of this study was to develop a clinical rating instrument for short‐interval rating of festination and FOG. Foot movements of 33 patients were video taped and rated during 12 episodes in a standardized course on a four‐level interval scale according to severity. Motor blocks were provoked in four situations and by three levels of dual‐tasking (tasks). Addition of the item scores produced a FOG score. The assessment requires less than 15 min. The inter‐rater and re‐test reliability of the FOG score is high (Kendall κ = 0.85–0.92, P < 0.0001). Variability of the item scale due to situations and tasks can be attributed to unidimensional group factors (Cronbach's α 0.84 and 0.94). Group comparisons and a logistic regression model show significant effects for both situations and tasks on the item scale (Friedman test: “situation”: P < 0.0001, “task”: P < 0.0001). Six patients with PD have significantly different scores during mobile (practical ON; 6.2 ± 3.9) and immobile (practical OFF; 15.8 ± 4.6) medication states (P < 0.05). The FOG score correlates with the 10 m number of steps (ρ = 0.58; P = 0.001) and with the self‐evaluation of FOG (ρ = 0.51; P < 0.01). Our results encourage the further use of the FOG score to evaluate festination and FOG. © 2010 Movement Disorder Society
Tremulous arytenoid movements predict severity of glottic stenosis in multiple system atrophy
Authors: Ozawa Tetsutaro , Shinoda Hideo , Tomita Masahiko , Shimohata Takayoshi , Nakayama Hideaki , Nishizawa Masatoyo
Published: March 2010

To determine whether tremulous arytenoid movements predict the severity of glottic stenosis in patients with multiple system atrophy (MSA), 28 MSA patients and 14 age‐matched controls underwent fiberoptic laryngoscopy with video monitoring during wakefulness and under anesthesia induced by intravenous injection of propofol. Presence or absence of tremulous arytenoid movements was recorded during wakefulness. The ratio of glottic stenosis (%), which represents the extent of airway narrowing under anesthesia, was obtained by measuring the inspiratory glottic angle during wakefulness and under anesthesia. The median ratio of glottic stenosis was significantly higher in patients with MSA (57.5%) than in control subjects (0.5%). Tremulous arytenoid movements were characterized by shaking movements of the arytenoid region including the vocal folds, which are most apparent in the arytenoid cartilage. In this study, tremulous arytenoid movements were observed in 18 (64.2%) of 28 patients with MSA, who displayed a significantly higher median ratio of glottic stenosis (71.2%) than other patients (34.9%). None of the control subjects exhibited tremulous arytenoid movements. A clear correlation existed between the ratio of glottic stenosis and disease duration. Our observations indicate that tremulous arytenoid movements are a marker of the severity of glottic stenosis, which confers an increased risk of upper airway obstruction in patients with MSA. © 2010 Movement Disorder Society
Development of a portocaval shunt using a small intestinal segment in rats
Authors: Hata Toshiyuki , Iwasaki Junji , Hishikawa Shuji , Fujimoto Yasuhiro , Uemoto Shinji , Kobayashi Eiji
Published: March 2010

The transjugular portosystemic shunt, widely used to treat portal hypertension today, may increase the risk of encephalopathy and reduce effective hepatic flow. To address these issues, a strategy to produce a portocaval shunt (PCS) with hepatic function using intestinal grafts was conceived, and rat models were developed. We transplanted ileal grafts from wild‐type and luciferase transgenic Lewis rats to wild‐type Lewis rats, anastomosing the graft mesenteric artery (SMA) and portal vein (PV) to the recipient PV trunk and inferior vena cava, respectively. Recipient survival was significantly longer in the partial PCS model, in which the graft SMA was anastomosed to the recipient PV trunk in an end‐to‐side fashion, than in the total PCS model, with the end‐to‐end anastomosis. In the partial PCS model, histological and luminescence analyses showed graft survival for 1 month. These results suggest that intestinal grafts can be maintained in the particular conditions required for our strategy. © 2010 Wiley‐Liss, Inc. Microsurgery, 2010.
Improvement of the skin flap survival with the bone marrow‐derived mononuclear cells transplantation in a rat model
Authors: Yang Mei , Sheng Lingling , Li Hua , Weng Rui , Li Qing‐Feng
Published: March 2010

Partial necrosis of skin flaps remains a significant problem in plastic and reconstructive surgery. In this study we attempted to evaluate the effect of bone marrow‐derived mononuclear cells (BM‐MNCs) transplantation on improvement of skin flap survival in a rat random pattern skin flap model. Thirty Wistar rats were divided into three groups with each consisting of 10 rats. BM‐MNCs and the adipose‐derived stem cells (ADSCs) were transplanted into the subcutaneous tissue in the area where the flap would be dissected. The flaps were then raised two days after cells transplantation. The animals receiving the preoperative Dulbecco's Modified Eagle Medium (DMEM) treatment were used as the controls. On the 7th postoperative day, the survival areas of flaps were measured and tissues were collected for examinations. The results showed that the mean survival areas were 46.33 ± 13.46% in the ADSCs group and 50.06 ± 13.82% in the BM‐MNCs group as the percentages of the total skin flaps, which were significantly higher than that in the control group (26.33 ± 7.14%) (P < 0.05). Histological analysis showed increased neovascularization in the flap treated with BM‐MNCs when compared with ADSCs transplantation. Survival BM‐MNCs and ADSCs were detected in the flap tissues. Higher levels of the basic fibroblast growth factor (bFGF) and vascular endothelium growth factor (VEGF) were found in the BM‐MNCs transplantation group (P < 0.05). The findings from this study demonstrated that preoperative treatment with BM‐MNCs transplantation could promote neovascularization and improve flap survival. These effects of BM‐MNCs on flap survival were comparable with ADSCs transplantation, but without necessity of in vitro cells expansion. © 2010 Wiley‐Liss, Inc. Microsurgery, 2010
High‐resolution NMR correlation experiments in a single measurement (HR‐PANACEA)
Authors: Kupče Ēriks , Freeman Ray
Published: March 2010

Three important NMR pulse sequences, INADEQUATE, HSQC and three‐dimensional HMBC have been combined into a single entity called high‐resolution Parallel Acquisition NMR: an All‐in‐one Combination of Experimental Applications (HR‐PANACEA) to provide reliable structural information about a small molecule in a single measurement. This exploits a recent instrumental development that permits simultaneous acquisition of signals from several nuclear species, using multiple receivers. Where high‐precision values of the long‐range heteronuclear splittings are important, selected regions of a large experimental data matrix are extracted and examined with the highest possible resolution. The J‐doubling technique is then applied to derive precise values for these couplings. As proof of principle, the method is applied to the molecule of methyl salicylate, confirming the expected conformation of the COH moiety. Copyright © 2010 John Wiley & Sons, Ltd.
Type 2 Diabetes and Cancer: What Is the Connection?
Authors: Cannata Dara , Fierz Yvonne , Vijayakumar Archana , LeRoith Derek
Published: March 2010

Epidemiological studies have demonstrated an association between type 2 diabetes and cancer. Type 2 diabetes is characterized by insulin resistance and hyperinsulinemia. Hyperinsulinemia may lead to cancer through insulin's effect on its cognate receptor and the insulin‐like growth factor system. The effects of insulin and insulin‐like growth factor I on cancer development and progression have been demonstrated in animal and human studies. Type 2 diabetes has been positively associated with cancers of the breast, colon, and pancreas. An inverse relationship has been observed between type 2 diabetes and prostate cancer, and this may be due to lower testosterone levels in men with type 2 diabetes. Medications used to treat type 2 diabetes may affect cancer cells directly or indirectly by affecting serum insulin levels. Hyperinsulinemia may be an important risk factor for cancer as well as a target for cancer therapy. Mt Sinai J Med 77:197–213, 2010. © 2010 Mount Sinai School of Medicine
You Are Born with Your Genes: Justice and Protection against Discrimination in the Use of Genetic Information
Authors: Francis Leslie P.
Published: March 2010

Genetic information poses an apparent paradox for justice in health care. On the one hand, genetic information seems to be exactly the kind of information that it is unjust to take into account in the distribution of important goods. On the other hand, genetic information may increasingly become useful in individual patient care as evidence for personalized medicine increases. Although it is important to emphasize the difference between genetic information and the social construct of race, nonetheless, the historical interplay between discrimination based on assumptions about heritability and discrimination based on race are significant. Thus, this article defends the importance of paying very close attention to protections in the use of genetic information. Three current examples of inadequate protection are cited. First, informed consent to genetic testing should incorporate potential confidentiality risks raised by this information. Second, the Genetic Information Nondiscrimination Act is too porous to protect employees from their employers' possession of genetic information; if such information is used in discriminatory ways, burdens of seeking protection then fall on the employees. More stringent strategies for protecting information are thus desirable. Finally, current designs of interoperable health records fail to allow for the sequestration of genetic information. Efforts to develop such sequestration techniques should be encouraged; among other benefits, they would be helpful in shielding genetic information from employers. Mt Sinai J Med 77:188–196, 2010. © 2010 Mount Sinai School of Medicine
Genetics and Asthma Disease Susceptibility in the US Latino Population
Authors: Reibman Joan , Liu Mengling
Published: March 2010

The US Latino population is heterogeneous with diversity in environmental exposures and socioeconomic status. Moreover, the US Hispanic population derives from numerous countries previously under Spanish rule, and many Hispanics have complex proportions of European, Native American, and African ancestry. Disparities in asthma severity and control are due to complex interactions between environmental exposures, socioeconomic factors, and genetic variations. In addition, diseases within the Latino community may also differ by country of origin. Although US Census data show low asthma rates in the Hispanic population as a whole, there is a lot of variability in the prevalence and morbidity of asthma, with a prevalence of 5.0% in Mexican Americans versus 17.0% in Puerto Ricans. The diversity and population admixture make the study of the genetics of asthma complex in Latino populations. However, an understanding of the genetics of asthma in all populations, including the Latino population, can enhance risk identification, help us to target pharmacological therapy, and guide environmental regulations, all of which can promote a reduction in health disparities. The inclusion of markers of ancestral diversity and the incorporation of techniques to adjust for stratification now make these studies feasible in complex populations, including the Latino population. To date, studies using linkage analyses, genome‐wide associations, or candidate gene analyses have identified an association of asthma or asthma‐related phenotypes with candidate genes, including interleukin 13, β‐2 adrenergic receptor, a disintegrin and metalloproteinase 33, orosomucoid 1‐like 3, and thymic stromal lymphopoietin. As reviewed here, although these genes have been identified in diverse populations, limited studies have been performed in Latino populations, and they have had variable replication. There is a need for the development of registries with well‐phenotyped pediatric and adult Latino populations and subgroups for inclusion in the rapidly expanding field of genetic studies, and these studies need to be used to reduce health disparities. Mt Sinai J Med 77:140–148, 2010. © 2010 Mount Sinai School of Medicine
Access to Health and Health Care: How Race and Ethnicity Matter
Authors: Richardson Lynne D. , Norris Marlaina
Published: March 2010

Racial and ethnic disparities in health are multifactorial; they reflect differences in biological vulnerability to disease as well as differences in social resources, environmental factors, and health care interventions. Understanding and intervening in health inequity require an understanding of the disparate access to all of the personal resources and environmental conditions that are needed to generate and sustain health, a set of circumstances that constitute access to health. These include access to health information, participation in health promotion and disease prevention activities, safe housing, nutritious foods, convenient exercise spaces, freedom from ambient violence, adequate social support, communities with social capital, and access to quality health care. Access to health care is facilitated by health insurance, a regular source of care, and a usual primary care provider. Various mechanisms through which access to health and access to health care are mediated by race and ethnicity are discussed; these include the built environment, social environment, residential segregation, stress, racism, and discrimination. Empirical evidence supporting the association between these factors and health inequities is also reviewed. Mt Sinai J Med 77:166–177, 2010. © 2010 Mount Sinai School of Medicine
A stochastic gradual cover location problem
Authors: Drezner Tammy , Drezner Zvi , Goldstein Zvi
Published: March 2010

Covering models assume that a point is covered if it is within a certain distance from a facility and not covered beyond that distance. In gradual cover models it is assumed that a point is fully covered within a given distance from a facility, then cover gradually declines, and the point is not covered beyond a larger distance. Gradual cover models address the discontinuity in cover which may not be the correct approach in many situations. In the stochastic gradual cover model presented in this article it is assumed that the short and long distances employed in gradual cover models are random variables. This refinement of gradual cover models provides yet a more realistic depiction of actual behavior in many situations. The maximal cover model based on the new concept is analyzed and the single facility location cover problem in the plane is solved. Computational results illustrating the effectiveness of the solution procedures are presented. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010
Thermodynamically consistent phase‐field models of fracture: Variational principles and multi‐field FE implementations
Authors: Miehe C. , Welschinger F. , Hofacker M.
Published: March 2010

The computational modeling of failure mechanisms in solids due to fracture based on sharp crack discontinuities suffers in situations with complex crack topologies. This can be overcome by a diffusive crack modeling based on the introduction of a crack phase‐field. In this paper, we outline a thermodynamically consistent framework for phase‐field models of crack propagation in elastic solids, develop incremental variational principles and consider their numerical implementations by multi‐field finite element methods. We start our investigation with an intuitive and descriptive derivation of a regularized crack surface functional that Γ‐converges for vanishing length‐scale parameter to a sharp crack topology functional. This functional provides the basis for the definition of suitable convex dissipation functions that govern the evolution of the crack phase‐field. Here, we propose alternative rate‐independent and viscous over‐force models that ensure the local growth of the phase‐field. Next, we define an energy storage function whose positive tensile part degrades with increasing phase‐field. With these constitutive functionals at hand, we derive the coupled balances of quasi‐static stress equilibrium and gradient‐type phase‐field evolution in the solid from the argument of virtual power. Here, we consider a canonical two‐field setting for rate‐independent response and a time‐regularized three‐field formulation with viscous over‐force response. It is then shown that these balances follow as the Euler equations of incremental variational principles that govern the multi‐field problems. These principles make the proposed formulation extremely compact and provide a perfect base for the finite element implementation, including features such as the symmetry of the monolithic tangent matrices. We demonstrate the performance of the proposed phase‐field formulations of fracture by means of representative numerical examples. Copyright © 2010 John Wiley & Sons, Ltd.
Sperm analysis of patients after successful treatment of childhood acute lymphoblastic leukemia with chemotherapy
Authors: Marquis Adine , Kuehni Claudia E. , Strippoli Marie‐Pierre F. , Kühne Thomas , Brazzola Pierluigi
Published: March 2010

Survivors of childhood acute lymphoblastic leukemia (ALL) treated with radiotherapy are at risk for impaired fertility. Whether chemotherapy alone is also long‐term gonadotoxic is unclear. We assessed gonadal function in 11 male ALL‐survivors treated with the same chemotherapy regimen and compared sperm analysis to healthy men. While sex hormone levels were normal in all subjects, 5/11 survivors showed pathological sperm concentration and 4/11 a decreased total sperm count compared to WHO criteria. Compared to healthy controls, all quantitative parameters in semen analysis of survivors were decreased. This suggests that treatment with chemotherapeutic agents alone, even in moderate doses, might have a gonadotoxic effect. Pediatr Blood Cancer 2010;55:208–210. © 2010 Wiley‐Liss, Inc.
Effect of plasma treatment of silk fibroin powder on the properties of silk fibroin powder/polyurethane blend film
Authors: Zhu Lu , Xu Weilin , Ma Mingbo , Zhou Hao
Published: March 2010

In this study, silk fibroin powder was treated by dielectric barrier discharge (DBD) plasma. The objective is to improve the performance of the silk fibroin powder/polyurethane (PU) blend film used in biomechanical field. The scanning electron microscope (SEM) showed that the plasma‐treated powder was broken into small particles and the film from the treated powder became homogeneous and dense. Fourier transform infrared spectroscopy (FTIR) revealed that the hydrophobic groups in silk fibroin powder were oxidized during plasma treatment. Little change in chemical composition was found on the surface of the blend film from plasma‐treated powder. The fracture strain of the blend film from plasma‐treated powder was remarkably raised, whereas its tensile strength was influenced significantly by the plasma treatment conditions. The wet‐out time of the plasma‐treated powder/PU film was shortened considerably. This indicates the improved hydrophilicity of the blend film. In addition, the decreased values of water vapor permeability suggested that the structure of the blend film became dense. This might result from the strong interfacial adhesion between plasma‐treated powder and PU. POLYM. ENG. SCI., 50:1705–1712, 2010. © 2010 Society of Plastics Engineers
Proton conduction in 1H‐1,2,3‐triazole polymers: Imidazole‐like or pyrazole‐like?
Authors: Nagamani Chikkannagari , Versek Craig , Thorn Michael , Tuominen Mark T. , Thayumanavan S.
Published: March 2010

Proton transport (PT) plays an important role in many biological processes as well as in materials for renewable energy devices. Gaining insights into functional group requirements for PT would aid the design of new materials that provide enhanced proton conduction. In this report, we outline our efforts to understand the most probable proton conduction pathway in 1H‐1,2,3‐triazole systems. In triazole‐based systems, both imidazole‐ and pyrazole‐like pathways are possible. By systematically comparing structurally analogous polymers based on N‐heterocycles and benz‐N‐heterocycles, we find that the imidazole‐like pathway makes a significant contribution to the proton transfer in 1H‐1,2,3‐triazole systems, while the contribution from pyrazole‐like pathway is negligible. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1851–1858, 2010
Iridium complex grafted to 3,6‐carbazole‐alt‐tetraphenylsilane copolymers for blue electrophosphorescence
Authors: Fei Teng , Cheng Gang , Hu Dehua , Dong Wenyue , Lu Ping , Ma Yuguang
Published: March 2010

We designed a 3,6‐dibromo‐9‐hexyl‐9H‐carbazole derivative with the blue emissive iridium complex bis[2‐(4,6‐difluorophenyl)pyridyl‐N,C2′](picolinato)iridium(III) (FIrpic) linked at the alkyl terminal. Based on this monomer, novel 3,6‐carbazole‐alt‐tetraphenylsilane copolymers grafted with FIrpic were synthesized by palladium‐catalyzed Suzuki coupling reaction, and the content of FIrpic in the polymers could be controlled by feed ratio of the monomers. The polymer films mainly show blue emission from FIrpic, and the emission intensity from the polymer backbones is much weaker compared with the doped analogues, which demonstrates an efficient energy transfer from polymeric host to covalently bonded guest. The phase separation in the polymers was suppressed, which can be identified by atomic force microscopy and designed electroluminescent (EL) devices. EL devices based on the polymers exhibited blue phosphorescence from FIrpic. The luminous efficiency of preliminary devices reached 2.3 cd/A, and the efficiency roll‐off at high current densities was suppressed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1859–1865, 2010
Polymethylene‐b‐polystyrene diblock copolymer: Synthesis, property, and application
Authors: Chen Jian‐Zhuang , Zhao Qiao‐Ling , Lu Hui‐Chao , Huang Jin , Cao Shao‐Kui , Ma Zhi
Published: March 2010

The design and synthesis of well‐defined polymethylene‐b‐polystyrene (PM‐b‐PS, Mn = 1.3 × 104–3.0 × 104 g/mol; Mw/Mn (GPC) = 1.08–1.18) diblock copolymers by the combination of living polymerization of ylides and atom transfer radical polymerization (ATRP) was successfully achieved. The 1H NMR spectrum and GPC traces of PM‐b‐PS indicated the successful extension of PS segment on the PM macroinitiator. The micellization behavior of such diblock copolymers in tetrahydrofuran were characterized by dynamic light scattering (DLS) and atomic force microscopy (AFM) techniques. The average aggregate sizes of PM‐b‐PS diblock copolymers with the same length of PM segment in tetrahydrofuran solution (1.0 mg mL−1) increases from 104.2 nm to 167.7 nm when the molecular weight of PS segment increases. The spherical precipitated aggregates of PM‐b‐PS diblock copolymers with an average diameter of 600 nm were observed by AFM. Honeycomb porous films with the average diameter of 3.0 μm and 6.0 μm, respectively, were successfully fabricated using the solution of PM‐b‐PS diblock copolymers in carbon disulfide via the breath‐figure (BF) method under a static humid condition. The cross‐sections of low density polyethylene (LDPE)/polystyrene (PS)/PM‐b‐PS and LDPE/polycarbonate (PC)/PM‐b‐PS blends were observed by scanning electron microscope and reveal that the PM‐b‐PS diblock copolymers are effective compatilizers for LDPE/PS and LDPE/PC blends. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1894–1900, 2010
Synthesis, characterization, and field‐effect transistor performance of poly[2,6‐bis(3‐tridecanoxythiophen‐2‐yl)benzo[1,2‐b;4,5‐b′]dithiophene]
Authors: Leenen Mark A. M. , Meyer Tim , Cucinotta Fabio , Thiem Heiko , Anselmann Ralf , De Cola Luisa
Published: March 2010

A new copolymer of benzo[1,2‐b:4,5‐b′]dithiophene and 3,3′‐bis(tridecanoxy)‐5,5′‐bithiophene was synthesized through Stille copolymerization. The bis‐(3‐alkoxythiophene) monomer was synthesized through a silver fluoride mediated, palladium‐catalyzed cross‐coupling, in which bromide functional groups were preserved instead of consumed. The copolymer has been characterized and applied in field‐effect transistors, giving a hole mobility of 2 × 10−3 cm2/Vs and an on/off ratio >106, with negligible hysteresis, on standard silicon substrates. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1973–1978, 2010
Frontal cationic curing of epoxy resins
Authors: Scognamillo Sergio , Bounds Chris , Luger Michael , Mariani Alberto , Pojman John A.
Published: March 2010

We studied the frontal curing of trimethylolpropane triglycidyl ether (TMPTGE) using two BF3‐amine initiators and two fillers, kaolin and fumed silica. In the case of kaolin, the range of concentrations allowing for frontal polymerization to propagate was dependent on its heat absorption effect whereas in the case of silica it was a consequence of the rheological features of this additive. However, for both systems the velocity and front temperature show the same trends; in all cases front velocities were on the order of 1 cm/min with front temperatures about 200 °C. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2000–2005, 2010
Stimulus‐responsive polymers based on 2‐hydroxypropyl acrylate prepared by RAFT polymerization
Authors: Vo Cong‐Duan , Rosselgong Julien , Armes Steven P. , Tirelli Nicola
Published: March 2010

Homopolymerization and diblock copolymerization of 2‐hydroxypropyl acrylate (HPA) has been conducted using reversible addition fragmentation chain transfer (RAFT) chemistry in tert‐butanol at 80 °C. PHPA homopolymers were obtained with high conversions and narrow molecular weight distributions over a wide range of target degrees of polymerization. Like its poly(2‐hydroxyethyl methacrylate) isomer, PHPA homopolymer exhibits inverse temperature solubility in dilute aqueous solution, with cloud points increasing systematically on lowering the mean chain length. The nature of the end groups is shown to significantly affect the cloud point, whereas no effect of concentration was observed over the PHPA concentration range investigated. Various thermoresponsive PHPA‐based diblock copolymers were prepared via one‐pot syntheses in which the second block was either permanently hydrophilic or pH‐responsive. Preliminary studies confirmed that poly(ethylene oxide)‐poly(2‐hydroxypropyl acrylate) (PEO45‐PHPA48) and poly(2‐hydroxypropyl acrylate)‐ poly(2‐hydroxyethyl acrylate) (PHPA49‐PHEA68)diblock copolymers formed well‐defined PHPA‐core micelles in 10 mM sodium nitrate solution at 40 °C and 70 °C with mean hydrodynamic diameters of 20 nm and 35 nm, respectively. In contrast, most other PHPA‐based diblock copolymers investigated formed larger colloidal aggregates in 10 mM NaNO3 solution at elevated temperatures. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2032–2043, 2010
Evaluation of light scattering models to characterize concentrated polymer particles embedded in a solid polymer matrix
Authors: Otero Fernando A. , Frontini Gloria L. , Eliçabe Guillermo E.
Published: March 2010

This work deals with the application of the static light scattering (SLS) model of Vrij (VM) for the characterization of a spherical polydisperse concentrated polymer particle system. This model is the exact solution for the SLS of such mixture of particles in the Percus–Yevick approximation. The analyzed polymer particle samples are obtained by solution polymerization of isobornyl methacrylate in polyisobutylene. At the end of the polymerization, as a result of phase separation, a particle system of micrometer sized particles with a moderate distribution of sizes and a volume fraction between 5 and 10% is formed. The SLS data were also analyzed using the local monodisperse approximation (LMA), a well‐known approximation to the model of Vrij. As expected, the estimations with the VM gave better results than those performed with the LMA model for the parameters related to the shape of the particle size distribution as compared with independent determinations of these quantities obtained from scanning electron microscopy micrographs. However, the main motivation to use the more rigorous model seems to be the fact that the volume fraction of particles can be extracted from the data even when relative SLS measurements are used. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 958–963, 2010
Exchange with temperature of the electron‐vibrational mode interaction between thienylene–phenylene copolymer rings
Authors: Silva R. A. , Cury L. A. , Guimarães P. S. S. , Marletta Alexandre , Serein‐Spirau F. , Bouachrine M. , Moreau J. J. E. , Lère‐Porte J.‐P.
Published: March 2010

Thienylene–dialkoxyphenylene copolymers with polar side chains are soluble in most organic solvents and exhibit excellent glass adhesion properties, allowing the formation of homogeneous thin films on glass, quartz, and other substrates by spin coating. The electrochemical and optical properties of thin films of this material are studied in this work. The calculated band gap derived from electrochemical data (2.34 eV) is in good agreement with that observed from the UV–vis spectrum edge (2.25 eV). The analysis of the emission properties reveals the strong dependence on temperature of the electron coupling with different vibrational modes in the formation of the vibronic bands. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 964–971, 2010
Crystallization kinetics study of poly(L‐lactic acid)/carbon nanotubes nanocomposites
Authors: Shieh Yeong‐Tarng , Twu Yawo‐Kuo , Su Chean‐Cheng , Lin Rong‐Hsien , Liu Gin‐Lung
Published: March 2010

Effects of carbon nanotubes (CNT) on the isothermal crystallization kinetics of poly(L‐lactic acid) (PLLA) were quantitatively investigated using the Avrami equation and the secondary nucleation theory of Lauritzen and Hoffman. CNT via grafting modification with PLLA could well disperse in the PLLA matrix and give significantly enhanced crystallization rate and crystallinity of PLLA as analyzed by differential scanning calorimetry and polarized optical microscopy. Analysis of isothermal crystallization kinetics using the Avrami equation demonstrated that CNT significantly enhanced the bulk crystallization of PLLA. Analysis of spherulite growth kinetics using the secondary nucleation theory of Lauritzen and Hoffman found that CNT could expand the temperature range of the crystallization regime III of PLLA. Values of the nucleation constant (Kg) in crystallization regimes III and II of PLLA both increased with increasing CNT contents. The Kg III/Kg II ratios were found to be close to the theoretical value 2 but were not clearly found to depend on the CNT contents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 983–989, 2010
Dielectric, thermal, and mechanical properties of CeO2‐filled HDPE composites for microwave substrate applications
Authors: Anjana P. S. , Deepu V. , Uma S. , Mohanan P. , Philip J. , Sebastian M. T.
Published: March 2010

Cerium oxide‐filled high density polyethylene (HDPE) composites for microwave substrate applications were prepared by sigma‐blend technique. The HDPE was used as the matrix and the dispersion of CeO2 in the composite was varied up to 0.5 by volume fraction, and the dielectric properties were studied at 1 MHz and microwave frequencies. The variations of thermal conductivity (keff), coefficient of thermal expansion (αc) and Vicker's microhardness with the volume fraction of the filler were also measured. The relative permittivity (εeff) and dielectric loss (tan δ) were found to increase with increase in CeO2 content. For 0.4 volume fraction loading of the ceramic, the composite had εeff = 5.7, tan δ = 0.0068 (at 7 GHz), keff = 2.6 W/m °C, αc = 98.5 ppm/°C, Vicker's microhardness of 18 kg/mm2 and tensile strength of 14.6 MPa. Different theoretical approaches have been used to predict the effective permittivity, thermal conductivity, and coefficient of thermal expansion of composite systems and the results were compared with the experimental data. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 998–1008, 2010
Time‐resolved photoelectron nano‐spectroscopy of individual silver particles: Perspectives and limitations
Authors: Rohmer Martin , Bauer Michael , Leissner Till , Schneider Christian , Fischer Alexander , Niedner‐Schatteburg Gereon , Issendorff Bernd v. , Aeschlimann Martin
Published: March 2010

Simultaneous time‐ and energy‐resolved two‐photon photoemission with nanometer resolution is demonstrated for the first time. We monitor the energy dependence of the decay dynamics of electron excitations in individual silver particles, which were deposited from a gas aggregation cluster source onto a silicon substrate. We show furthermore that the near‐field enhancement due to plasmon‐resonant excitation is an efficient means to address individual nanometer‐sized particles using photoemission electron microscopy.
A flexible class of models for data arising from a ‘thorough QT/QTc study’
Authors: Anand Suraj P. , Ghosh Sujit K.
Published: March 2010

The standard methods for analyzing data arising from a ‘thorough QT/QTc study’ are based on multivariate normal models with common variance structure for both drug and placebo. Such modeling assumptions may be violated and when the sample sizes are small, the statistical inference can be sensitive to such stringent assumptions. This article proposes a flexible class of parametric models to address the above‐mentioned limitations of the currently used models. A Bayesian methodology is used for data analysis and models are compared using the deviance information criteria. Superior performance of the proposed models over the current models is illustrated through a real dataset obtained from a GlaxoSmithKline (GSK) conducted ‘thorough QT/QTc study’. Copyright © 2010 John Wiley & Sons, Ltd.
Effects of component properties and orientation on corrugated container endurance
Authors: Popil Roman E. , Hojjatie Barry
Published: March 2010

Experiments are performed to determine the impact of several physical properties on the creep behavior of three different sets of corrugated containers subjected to static loading and a cyclic humidity environment ranging from 50% to 80% relative humidity in a 24 h period. One sample set had basis weights of the fluted medium varied from 68 to 205 g/m2 while keeping the basis weight of the linerboard facings at 205 g/m2. This varied the out‐of‐plane shear rigidity of the single wall board by a factor of three. Another set of corrugated samples investigated effects of lateral or linear corrugating by rotation of either linerboards, fluted medium or both. This equalizes hygroexpansivity and affects lifetime. A third series of boxes had barrier coatings applied to their surfaces to determine the effect on lifetime. Creep and lifetime are determined to be inversely related and a multiple regression model for lifetime was sought based on the data set. Homogenization of the corrugated board properties through either increased medium basis weight or component rotation (lateral or linear corrugating) and application of barrier coating will in general, increase the endurance of edge loaded corrugated board in cyclic humidity. Copyright © 2010 John Wiley & Sons, Ltd.
New tactile sensing system for minimally invasive surgical tumour localization
Authors: Perri M. T. , Trejos A. L. , Naish M. D. , Patel R. V. , Malthaner R. A.
Published: March 2010

Background

Minimally invasive surgery (MIS) suffers from the inability to directly palpate organs for tumour localization. A tactile sensing system (TSS), consisting of a probe and a visualization interface, was developed to present an active pressure map of the contact surface to locate tumours during MIS.

Methods

The TSS performance was compared to MIS graspers to locate occult 10 mm phantom tumours in ex vivo bovine liver and ex vivo porcine lung. Performance assessment included applied pressure, localization distance and accuracy.

Results

The TSS realized a relative 71% reduction in maximum applied pressure and a 31% increase in detection accuracy in liver tissue (when compared to MIS graspers) and demonstrated no significant differences in performance when palpating lung tissue.

Conclusions

The TSS may help surgeons to identify occult tumours during surgery by restoring some of the haptic information lost during MIS. Copyright © 2010 John Wiley & Sons, Ltd.
Influence of Manganese Oxide and Silica on the Morphological Structure of Hematite Compacts
Authors: El‐Geassy A.A. , Nasr M.I. , Mousa E.A.
Published: March 2010

Dry compacts of pure Fe2O3 and Fe2O3 doped with either (2–6 mass%) MnO2, (2.5–7.5 mass%) SiO2 or with both (2–6% MnO2 + 7.5% SiO2) were indurated at 1373 K for 6 hours and physically and chemically characterized. The fired compacts were isothermally reduced with pure CO gas at 1073–1373 K. The O2‐weight loss was continuously recorded as a function of time using TGA technique. The external volume of pure and doped compacts was measured at different reduction conditions and the volume change was calculated. The structural changes accompanying the reduction process were visually and microscopically examined and the different phases were identified by X‐ray diffraction analysis. After firing, manganese ferrite (MnFe2O4) phase was identified in MnO2‐doped compacts. In pure Fe2O3 compacts, the external volume of compacts was increased with reduction temperature, showing a maximum swelling value at 1198 K. Catastrophic swelling was observed in MnO2‐doped Fe2O3 compacts, the volume change increased with MnO2 content showing catastrophic swelling in compacts containing 6%MnO2 at 1248 K. The catastrophic swelling was attributed to the formation of dense metallic iron whiskers and plates in a highly porous structure. Unlike in MnO2‐doped samples, no considerable volume changes were detected in SiO2‐doped Fe2O3 and (MnO2 + SiO2)‐doped Fe2O3 compacts where the presence of silica greatly hindered the swelling phenomenon at all reduction temperatures.
Analysis of Microstructure and Mechanical Properties of Different Hot Stamped B‐bearing Steels
Authors: Naderi M. , Ketabchi M. , Abbasi M. , Bleck W.
Published: March 2010

Hot stamping is a technique to produce ultra high strength automobile components. The common material used in hot stamping process is coated and/or uncoated 22MnB5 boron alloyed steel. Ferritic‐pearlitic microstructure in as‐delivered sheets is transformed to fully lath martensitic after hot stamping. In the present research, hot stamping under water or nitrogen cooling media was investigated using different boron alloyed steel grades. Microstructural analyses, linear and surface hardness profiling as well as tensile tests of hot stamped samples were performed. Various microstructures of fully bainitic and/or fully martensitic were produced. The resulting microstructures provided yield strengths of 650–1370 MPa and tensile strengths of 850–2000 MPa. There is an optimum carbon equivalent content for which the highest formability index value, UTS × A25, is achieved. Using a nitrogen cooled punch resulted in higher yield strength without significant changes in ultimate tensile strength. It is concluded that a wide range of B‐bearing steels having an extended carbon equivalent range with an acceptable formability index value can be used by increasing the cooling rate in the die assembly.
Microstructure Transformations in Tempering Steels during Continuous Cooling from Hot Forging Temperatures
Authors: Nürnberger F. , Grydin O. , Schaper M. , Bach F.‐W. , Koczurkiewicz B. , Milenin A.
Published: March 2010

Apart from reducing the processing energy, hardening and tempering of near‐net shape forged components from their forging heat primarily promises shortened conventional process sequences. In this case, the continuous cooling transformation diagrams (CCT diagrams) found in the literature can only be used as a rough approximation of microstructural transformations during the heat‐treatment. The reasons for this are that firstly, the deformation influences the transformation kinetics and secondly, the deformation temperatures are comparatively high. Therefore, both deformation CCT diagrams and, for reference purposes, CCT diagrams without deformation were determined for a selection of heat‐treatable steels (34CrMo4, 42CrMo4, 52CrMo4, 51CrV4, 34NiMo6) at the heating temperature of 1200 °C and deformation levels of 0.3 and 0.6.
Effect of Carbon on Stainless Austenitic CrMnCN Steel Castings
Authors: Berns H. , Hussong B. , Riedner S. , Wischnowski F.
Published: March 2010

The effect of up to 0.5 mass% C on a steel with 18 to 19 mass% Cr and Mn each and about 0.6 mass% N was investigated by tensile tests, notch impact tests and corrosion tests. The experimental results show that the solution anneal temperature and the sensitisation to intercrystalline corrosion depend on the carbon content which raise the strength and cold work hardening. Up to 1 mass% C+N the ductile to brittle transition temperature remains at about −90 °C. Corrosion in diluted aqueous solutions of H2SO4, HCl and NaCl is described.