bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Strategy Targeting Well‐Defined Polymethylene‐block‐Polystyrene Copolymers: The Combination of Living Polymerization of Ylides and Atom Transfer Radical Polymerization
Authors: Chen Jian‐Zhuang , Cui Kun , Zhang Shu‐Yuan , Xie Peng , Zhao Qiao‐Ling , Huang Jin , Shi Li‐Ping , Li Guang‐Yu , Ma Zhi 
Published: February 2009

AbstractWell‐defined polymethylene‐block‐polystyrene (PM‐b‐PS) diblock copolymers were synthesized via a combination of living polymerization of ylides and atom transfer radical polymerization (ATRP) of styrene. A series of hydroxyl‐terminated polymethylenes (PM‐OHs) with different molecular weight and narrow molecular weight distribution were prepared using living polymerization of ylides following efficient oxidation in a quantitive functionality. Then, the macroinitiators (PM‐MIs ($\overline M _{\rm n}$ = 1 900–15 000; PDI = 1.12–1.23)) transformed from PM‐OHs in ≈ 100% conversion initiated ATRPs of styrene to construct PM‐b‐PS copolymers. The GPC traces indicated the successful extension of PS segment ($\overline M _{\rm n}$ of PM‐b‐PS = 5 000–41 800; PDI = 1.08–1.23). Such copolymers were characterized by 1H NMR and DSC.magnified image
Efficient Usage of Thiocarbonates for Both the Production and the Biofunctionalization of Polymers
Authors: Boyer Cyrille , Bulmus Volga , Davis Thomas P. 
Published: February 2009

AbstractEnd group modification of polymers prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization was accomplished by conversion of trithiocarbonate into reactive functions able to conjugate easily with biomolecules or bioactive functionality. Polymers were prepared by RAFT, and subsequent aminolysis led to sulfhydryl‐terminated polymers that reacted in situ with an excess of dithiopyridyl disulfide to yield pyridyl disulfide‐terminated macromolecules or in the presence of ene to yield functional polymers. In the first route, the pyridyl disulfide end groups allowed coupling with oligonucleotide and peptide. The second approach exploited thiol–ene chemistry to couple polymers and model compounds such as carbohydrate and biotin with high yield.magnified image
Particle Formation in RAFT‐Mediated Emulsion Polymerization: A Calorimetric Study
Authors: Leswin J. S. K. , Meuldijk J. , Gilbert R. G. , van Herk A. M. 
Published: February 2009

AbstractAb initio RAFT‐mediated semi‐continuous emulsion polymerizations with controlled monomer feed have been studied by reaction calorimetry. This online monitoring technique provided detailed information about the onset of the nucleation period in semi‐batch processes for emulsion polymerization of styrene and n‐butyl acrylate. The reactions were carried out under controlled radical polymerization conditions by employing amphipathic macro‐RAFT agents of various degrees of surface activity. For n‐butyl acrylate as well as for styrene the more surface active polymeric macro‐RAFT agents led to higher initial polymerization rates. Polymerizations with hydrophobic macro‐RAFT agents also adapted more quickly to an increased monomer feed than polymerizations with hydrophilic macro‐RAFT agents.This points to the presence of more particles when a hydrophobic macro‐RAFT agent is used. Hydrophobic macro‐RAFT agents demonstrated to be promising for producing latex products with a proper control of particle number and particle size distribution.
Entrepreneurial signaling to attract resources: the case of franchising
Authors: Michael Steven C. 
Published: February 2009

AbstractWhy firms and individuals reveal information is the subject of considerable theoretical research, but little empirical work has been possible due to a lack of suitable data. In this paper we examine why entrepreneurs selling business opportunities (franchisors) reveal information regarding potential profits (termed earnings claims). Empirical analysis shows that: first, contrary to theory, only a small percentage of franchisors claim; and, second, the franchisors that do claim have lower costs or are responding to competition. In particular, the prediction of theoretical models from economics that resource providers will not transact if information is not disclosed is not supported; resource providers can and do make significant investments even when entrepreneurs refuse to disclose information. Copyright © 2009 John Wiley & Sons, Ltd.
Magnetic resonance diffusion characteristics of histologically defined prostate cancer in humans
Authors: Xu Junqian , Humphrey Peter A. , Kibel Adam S. , Snyder Abraham Z. , Narra Vamsidhar R. , Ackerman Joseph J.H. , Song Sheng‐Kwei 
Published: February 2009

AbstractThe contrast provided by diffusion‐sensitive magnetic resonance offers the promise of improved tumor localization in organ‐confined human prostate cancer (PCa). Diffusion tensor imaging (DTI) measurements of PCa were performed in vivo, in patients undergoing radical prostatectomy, and later, ex vivo, in the same patients' prostatectomy specimens. The imaging data were coregistered to histological sections of the prostatectomy specimens, thereby enabling unambiguous characterization of diffusion parameters in cancerous and benign tissues. Increased cellularity, and hence decreased luminal spaces, in peripheral zone PCa led to approximately 40% and 50% apparent diffusion policy (ADC) decrease compared with benign peripheral zone tissues in vivo and ex vivo, respectively. In contrast, no significant diffusion anisotropy differences were observed between the cancerous and noncancerous peripheral zone tissues. However, the dense fibromuscular tissues in prostate, such as stromal tissues in benign prostatic hyperplasia in central gland, exhibited high diffusion anisotropy. A tissue classification method is proposed to combine DTI and T2‐weighted image contrasts that may provide improved specificity of PCa detection over T2‐weighted imaging alone. PCa identified in volume rendered MR images qualitatively correlates well with histologically determined PCa foci. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
High frequency of tumours in Mulibrey nanism
Authors: Karlberg Niklas , Karlberg Susann , Karikoski Riitta , Mikkola Sakari , Lipsanen‐Nyman Marita , Jalanko Hannu 
Published: February 2009

AbstractMulibrey nanism (MUL) is a monogenic disorder with prenatal‐onset growth failure, typical clinical characteristics, cardiopathy and tendency for a metabolic syndrome. It is caused by recessive mutations in the TRIM37 gene encoding for the peroxisomal TRIM37 protein with ubiquitin‐ligase activity. In this work, the frequency and pathology of malignant and benign tumours were analysed in a national cohort of 89 Finnish MUL patients aged 0.7–76 years. The subjects had a clinical and radiological evaluation, and histological and immunohistocemical analyses on specimens obtained from biopsy, surgery or autopsy, were performed. The results show that the MUL patients have disturbed architecture with ectopic tissues and a high frequency of both benign and malignant tumours detectable in several internal organs. A total of 210 tumorous lesions were detected in 66/89 patients (74%). Fifteen malignancies occurred in 13 patients (15%), seven of them in the kidney (five Wilms' tumours), three in the thyroid gland, two gynaecological cancers, one gastrointestinal carcinoid tumour, one neuropituitary Langerhans cell histiocytosis and one case of acute lymphoblastic leukaemia (ALL). Tumours detected by radiology in the liver and other organs mainly comprised strongly dilated blood vessels (peliosis), vascularized cysts and nodular lesions. The lesions showed strong expression of the endothelial cell markers CD34 and CD31 as well as the myocyte marker α‐smooth muscle actin (α‐SMA). Our findings show that MUL is associated with frequent malignant tumours and benign adenomatous and vascular lesions, as well as disturbed organ development. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Silicon‐containing liquid polymer electrolytes for application in lithium ion batteries
Authors: Rossi Nicholas AA , West Robert 
Published: February 2009

AbstractSince the initial discovery of poly(ethylene glycol) (PEG) as a good lithium ion conductor at elevated temperatures, efforts have been made to find ways of incorporating this biocompatible polymer into lithium ion batteries. In areas of research involving implantable medical devices, consumer electronics and automotive power sources, there is a need to develop a ‘safe’ alternative to the solvent‐based, flammable and toxic electrolytes currently employed. However, PEG has been shown to be electrochemically unstable and crystalline at room temperature. In order to overcome these problems, polysiloxanes have been conjugated to PEG in order to improve its conductivity and physical properties. Over the last few years, the group at the University of Wisconsin‐Madison has been involved in collaborations with scientists at Argonne National Laboratories, Grinnell College and Quallion LLC to develop commercially viable silicon‐containing polymer electrolytes. This mini‐review discusses the electrochemical, thermal and physical properties of these electrolytes, and highlights the progress from high molecular weight polysiloxane‐based electrolytes to low‐viscosity, highly conducting oligosiloxane and silane electrolytes. Copyright © 2009 Society of Chemical Industry
Chemical actuation in responsive hydrogels
Authors: Swann Joshua MG , Ryan Anthony J 
Published: February 2009

AbstractChemically actuated hydrogels share a unique feature with living systems: they are both driven by their ability to convert chemical energy into a mechanical response. However, macroscopic applications of hydrogels are limited due to the slow response rate of these materials. This problem has been overcome by developing materials at micrometre length scales, as the diffusion kinetics are related to the square of the size of the smallest dimension of the gel. Herein, the progress in the field of chemical actuation in hydrogel systems is reviewed, with an emphasis on the ways in which new devices have been designed. Copyright © 2009 Society of Chemical Industry
Sperm cell proteomics
Authors: Oliva Rafael , de Mateo Sara , Estanyol Josep Maria 
Published: February 2009

AbstractThe spermatozoon is an accessible cell which can be easily purified and therefore it is particularly well suited for proteomic analysis. It is also an extremely differentiated cell with very marked genetic, cellular, functional and chromatin changes as compared to other cells, and has profound implications for fertility, embryo development and heredity. The recent developments in MS have boosted the potential for identification and study of the sperm proteins. Catalogues of hundreds to thousands of spermatozoan proteins in human and in model species are becoming available setting up the basis for subsequent research, diagnostic applications and the development of specific treatments. The present article reviews the available scientific publications dealing with the composition and function of the sperm cell using an MS proteomic approach.
CNT templated regioselective enzymatic polymerization of phenol in water and modification of surface of MWNT thereby
Authors: Peng Yun , Liu Hewen , Zhang Xingyuan , Li Yuesheng , Liu Shiyong 
Published: February 2009

AbstractCarbon nanotubes (CNTs) are used as templates to synthesize regioselective polymers from enzymatic polymerization of phenol in water. About 90% of total polymeric units in the obtained polymers are the highly thermally stable oxyphenylene units. The polymer‐yields are dependent on the quantities of CNTs used. On the basis of MWNT‐templated enzymatic polymerization of phenol, covalent attachment of polyphenol chains to the surface of MWNT by way of a linking molecule, hydroquinone, is achieved. This approach supplies a novel way for producing high‐performance polymers and for functionalization of the surface of CNT. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1627–1635, 2009
Application of Plasma Surface Treatment to Solid‐State Microscopic Particulates
Authors: Sonnenfeld Axel , Spillmann Adrian , Arpagaus Cordin , Rudolf von Rohr Philipp 
Published: February 2009

AbstractThe plasma‐assisted improvement of wettability and flowability of fine powders is described. The plasma down‐stream reactor designed for an adequate treatment of particulates allows efficient surface modification and functionalization of particulates. It is discussed that the resulting rapidity of the processes is due to the homogeneous dispersion of particulates in the reactor. This enables intense particle/plasma interaction presumably due to the formation of floating potential sheaths around each single particle immersed in the plasma. Thus, although the overall energy influx applied is in the range of 10 to 100 J · m−2 of the particulate surfaces, the treatment time in the order of a tenth of a second instead of hours compared to conventional processes.magnified image
Non‐invasive assessment of exercise performance in children with cystic fibrosis (CF) and non‐cystic fibrosis bronchiectasis: Is there a CF specific muscle defect?
Authors: Rosenthal Mark , Narang Indra , Edwards Liz , Bush Andrew 
Published: February 2009

AbstractIntroductionPeripheral muscle dysfunction is increasingly recognized as complicating respiratory disease, but this is difficult to measure non‐invasively.Research QuestionCan skeletal muscle function and efficiency be measured during exercise non‐invasively using respiratory mass spectrometry (RMS); and is the known exercise dysfunction in cystic fibrosis (CF) children related in part to a disease specific defect of skeletal muscle, or a non‐specific manifestation of chronic airway infection and inflammation.MethodsCalculations of effective pulmonary blood flow and stroke volume, blood oxygen content and oxygen dispatch from the lungs, skeletal muscle oxygen extraction and consumption, anerobic threshold and capacity, and gross, net and work efficiency in 106 controls and 36 children (18 CF) with bronchiectasis, all aged from 8 to 17 years.ResultsNormal values for control subjects are tabulated. CF and non‐CF bronchiectatic subjects had similar physiology, and skeletal muscle abnormalities could not be detected. Reduced oxygen dispatch from the lungs, due to an inability to raise stroke volume, without an increase in functional residual capacity was the major factor in reduced exercise ability.ConclusionsNon‐invasive RMS can be used to determine skeletal muscle function in children. The changes observed in CF subjects were very similar to non‐CF bronchiectatic subjects and thus a CF specific defect was not demonstrated. Pediatr Pulmonol. 2009; 44:222–230. © 2009 Wiley‐Liss, Inc.
Recommendations for treatment of intermittent mild persistent asthma in children and adolescents
Authors: Naspitz Charles K. , Cropp Gerd J. 
Published: February 2009

AbstractMany parents and caretakers of children and adolescents with mild persistent asthma (MPA) do not follow proposed guidelines, namely the daily and continuous administration of inhaled corticosteroids (ICS). Instead, parents and caretakers tend to use ICS and bronchodilators intermittently for short periods and restart such therapy only when symptoms reappear. It is our opinion that intermittent treatment of MPA in children and adolescents might achieve the same level of asthma control as has been achieved in adults. We propose, therefore, that after an initial period of stabilization with age‐appropriate doses of oral glucocorticoids or high‐dose ICS and short‐acting beta‐2 agonists (SABA), caretakers can stop treatment once there are no longer signs or symptoms of asthma. When asthmatic symptoms recur, treatment should be restarted with ICS and SABA, or oral corticosteroids if the exacerbation is severe. The perception of developing asthma symptoms remains an unsolved problem. Based on our clinical experience in children and adolescents with asthma, we list a number of signs and symptoms that precede an exacerbation of asthma, allowing for an early re‐introduction of treatment to prevent an exacerbation. Pediatr Pulmonol. 2009; 44:205–208. © 2009 Wiley‐Liss, Inc.
Airway humidification with a heated wire humidifier during high‐frequency ventilation using babylog 8000 plus® in neonates
Authors: Nagaya Ken , Okamoto Toshio , Nakamura Eiki , Hayashi Tokitsugi , Fujieda Kenji 
Published: February 2009

AbstractObjectiveLittle data are available on airway humidity during high‐frequency ventilation (HFV). Our purpose is to evaluate the airway humidification during HFV.MethodsWe examined the airway humidification and temperature in a neonatal HFV system using Babylog 8000 plus®. The absolute humidity (AH), relative humidity (RH), and temperature at different sites and under different HFV conditions were compared with those during conventional intermittent positive pressure ventilation (IPPV).ResultsThe mean AH and RH at the patient end of the respiratory circuit under 37°C in the humidification chamber (HC) during HFV were less than 35 mg/L and 65%, respectively, while those during IPPV were 42.3 mg/L and 96.8%, respectively. The humidification at the outlet of the HC was similar results. Moreover, during HFV an increase in the bias‐flow of ventilator led to a further decrease in the humidity at the patient end of respiratory circuit and the outlet of HC. It was necessary to set the temperature in the HC at >39°C to maintain adequate humidity at the HC and the patient end of respiratory circuit during HFV. An increase in the incubator temperature led to an increase in the temperature at the patient end of the respiratory circuit. The temperature at the patient end of the respiratory circuit was about 39–40°C when the incubator temperature was 35–37°C.ConclusionsThe airway humidification at the patient end of respiratory circuit and the outlet of HC in HFV were poorer than those in IPPV. However, the adequacy of humidification and safety in HFV remain to be demonstrated in clinical practice. Pediatr Pulmonol. 2009; 44:260–266. © 2009 Wiley‐Liss, Inc.
Structural basis for chloramphenicol tolerance in Streptomyces venezuelae by chloramphenicol phosphotransferase activity
Authors: Izard Tina 
Published: February 2009

AbstractStreptomyces venezuelae synthesizes chloramphenicol (Cm), an inhibitor of ribosomal peptidyl transferase activity, thereby inhibiting bacterial growth. The producer escapes autoinhibition by its own secondary metabolite through phosphorylation of Cm by chloramphenicol phosphotransferase (CPT). In addition to active site binding, CPT binds its product 3‐phosphoryl‐Cm, in an alternate product binding site. To address the mechanisms of Cm tolerance of the producer, the crystal structures of CPT were determined in complex with either the nonchlorinated Cm (2‐N‐Ac‐Cm) at 3.1 Å resolution or the antibiotic's immediate precursor, the p‐amino analog p‐NH2‐Cm, at 2.9 Å resolution. Surprisingly, p‐NH2‐Cm binds CPT in a novel fashion. Additionally, neither 2‐N‐Ac‐Cm nor p‐NH2‐Cm binds to the secondary product binding site.
In Memoriam: Professor G.N. Ramachandram (1922–2001)
Authors: Ramakrishnan C. 
Published: February 2009

AbstractEditor's note: Few scientists contribute an idea of such clarity and power that it appears in all the discipline's textbooks and bears the author's name. For the contribution to be relevant and universally employed almost forty years after it first appeared is even less common. Structural biology lost the author of such an idea with the death of G.N. Ramachandran, whose picture appears on the cover of this issue of Protein Science. His seminal contribution is described in remembrances of Professor Ramachandran's life and career by colleague and co‐author of the 1963 paper, C. Ramakrishnan. A perspective by George D. Rose follows, which articulates the enduring impact of that work.
Walker‐A threonine couples nucleotide occupancy with the chaperone activity of the AAA+ ATPase ClpB
Authors: Nagy Maria , Wu Hui‐Chuan , Liu Zhonghua , Kedzierska‐Mieszkowska Sabina , Zolkiewski Michal 
Published: February 2009

AbstractHexameric AAA+ ATPases induce conformational changes in a variety of macromolecules. AAA+ structures contain the nucleotide‐binding P‐loop with the Walker A sequence motif: GxxGxGK(T/S). A subfamily of AAA+ sequences contains Asn in the Walker A motif instead of Thr or Ser. This noncanonical subfamily includes torsinA, an ER protein linked to human dystonia and DnaC, a bacterial helicase loader. Role of the noncanonical Walker A motif in the functionality of AAA+ ATPases has not been explored yet. To determine functional effects of introduction of Asn into the Walker A sequence, we replaced the Walker‐A Thr with Asn in ClpB, a bacterial AAA+ chaperone which reactivates aggregated proteins. We found that the T‐to‐N mutation in Walker A partially inhibited the ATPase activity of ClpB, but did not affect the ClpB capability to associate into hexamers. Interestingly, the noncanonical Walker A sequence in ClpB induced preferential binding of ADP vs. ATP and uncoupled the linkage between the ATP‐bound conformation and the high‐affinity binding to protein aggregates. As a consequence, ClpB with the noncanonical Walker A sequence showed a low chaperone activity in vitro and in vivo. Our results demonstrate a novel role of the Walker‐A Thr in sensing the nucleotide's γ‐phosphate and in maintaining an allosteric linkage between the P‐loop and the aggregate binding site of ClpB. We postulate that AAA+ ATPases with the noncanonical Walker A might utilize distinct mechanisms to couple the ATPase cycle with their substrate‐remodeling activity.
Genetic selection system for improving recombinant membrane protein expression in E. coli
Authors: Massey‐Gendel Elizabeth , Zhao Anni , Boulting Gabriella , Kim Hye‐Yeon , Balamotis Michael A. , Seligman Len M. , Nakamoto Robert K. , Bowie James U. 
Published: February 2009

AbstractA major barrier to the physical characterization and structure determination of membrane proteins is low yield in recombinant expression. To address this problem, we have designed a selection strategy to isolate mutant strains of Escherichia coli that improve the expression of a targeted membrane protein. In this method, the coding sequence of the membrane protein of interest is fused to a C‐terminal selectable marker, so that the production of the selectable marker and survival on selective media is linked to expression of the targeted membrane protein. Thus, mutant strains with improved expression properties can be directly selected. We also introduce a rapid method for curing isolated strains of the plasmids used during the selection process, in which the plasmids are removed by in vivo digestion with the homing endonuclease I‐CreI. We tested this selection system on a rhomboid family protein from Mycobacterium tuberculosis (Rv1337) and were able to isolate mutants, which we call EXP strains, with up to 75‐fold increased expression. The EXP strains also improve the expression of other membrane proteins that were not the target of selection, in one case roughly 90‐fold.