bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrolysis of Phosphotriesters: A Theoretical Analysis of the Enzymatic and Solution Mechanisms
Authors: López‐Canut Violeta , Ruiz‐Pernía J. Javier , Castillo Raquel , Moliner Vicent , Tuñón Iñaki 
Published: June 2012

AbstractA theoretical study on the alkaline hydrolysis of paraoxon, one of the most popular organophosphorus pesticides, in aqueous solution and in the active site of Pseudomonas diminuta phosphotriesterase (PTE) is presented. Simulations by means of hybrid quantum mechanics/molecular mechanics (QM/MM) potentials show that the hydrolysis of paraoxon takes place through an ANDN or associative mechanism both in solution and in the active site of PTE. The results correctly reproduce the magnitude of the activation free energies and can be used to rationalize the observed kinetic isotope effects (KIEs) for the hydrolysis of paraoxon in both media. Enzymatic hydrolysis of O,O‐diethyl p‐chlorophenyl phosphate, a phosphotriester having a leaving group with higher pKa than paraoxon, was also simulated. Hydrolysis of this phosphotriester by PTE follows a AN+DN mechanism with a pentacoordinate intermediate. Moreover, the leaving group of this new substrate coordinates to one of the zinc ions of the bimetallic active site in order to stabilize the large negative charge developed on the oxygen atom of the leaving group when the PO bond is broken in the products state. To accommodate this new ligand in the coordination shell, carbamylated Lys169 must be displaced from one zinc ion to the other, which in turn affects the acidity of Asp301, a residue originally bound to the second zinc ion. This ability to displace some of the ligands of the coordination shell of the zinc centers would explain the promiscuity of this enzyme, which is capable of catalyzing hydrolysis of different substrate by means of different mechanisms.
Supramolecular‐Tilt‐Chirality on Twofold Helical Assemblies
Authors: Hisaki Ichiro , Sasaki Toshiyuki , Tohnai Norimitsu , Miyata Mikiji 
Published: June 2012

AbstractA twofold helix (21 helix) is an essential motif in approximately 70 % of organic crystals. Although handedness of 21 helix has not been discussed from a mathematical viewpoint, we noticed that the handedness can be defined by considering the molecular shape and manner of assembly. Herein we propose the supramolecular‐tilt‐chirality (STC) method to define the handedness, and illustrate it by way of some examples. We believe that establishment of the systematic rules for supramolecular chirality will contribute to the progression of supramolecular chemistry and material science.
Glycosylated Star‐Shaped Conjugated Oligomers for Targeted Two‐Photon Fluorescence Imaging
Authors: Wang Guan , Zhang Xinhai , Geng Junlong , Li Kai , Ding Dan , Pu Kan‐Yi , Cai Liping , Lai Yee‐Hing , Liu Bin 
Published: June 2012

AbstractA glucopyranose functionalized star‐shaped oligomer, N‐tris{4,4′,4′′‐[(1E)‐2‐(2‐{(E)‐2‐[4‐(benzo[d]thiazol‐2‐yl)phenyl]vinyl}‐9,9‐bis(6‐2‐amido‐2‐deoxy‐1‐thio‐β‐D‐glucopyranose‐hexyl)‐9H‐fluoren‐7‐yl)vinyl]phenyl}phenylamine (TVFVBN‐S‐NH2), is synthesized for two‐photon fluorescence imaging. In water, TVFVBN‐S‐NH2 self‐assembles into nanoparticles with an average diameter of ∼49 nm and shows a fluorescence quantum yield of 0.21. Two‐photon fluorescence measurements reveal that TVFVBN‐S‐NH2 has a two‐photon absorption cross‐section of ∼1100 GM at 780 nm in water. The active amine group on the glucopyranose moiety allows further functionalization of TVFVBN‐S‐NH2 with folic acid to yield TVFVBN‐S‐NH2FA with similar optical and physical properties as those for TVFVBN‐S‐NH2. Cellular imaging studies reveal that TVFVBN‐S‐NH2FA has increased uptake by MCF‐7 cells relative to that for TVFVBN‐S‐NH2, due to specific interactions between folic acid and folate receptors on the MCF‐7 cell membrane. This study demonstrates the effectiveness of glycosylation as a molecular engineering strategy to yield water‐soluble materials with a large two‐photon absorption (TPA) cross‐section for targeted cancer‐cell imaging.
Elektrochemisches Schreiben & Löschen und noch mehr!
Authors: Brenner Tatjana , Kunz Isabella , Ducci Matthias 
Published: June 2012

AbstractIn diesem Beitrag werden neue Experimente zum Themenfeld „Elektrochemisches Schreiben“ vorgestellt. Beim elektrochemischen Schreiben wird mit einer Elektrode auf Filterpapier geschrieben, das zuvor in einer speziellen Lösung getränkt wurde. Hierbei zeigen sich faszinierende Effekte, da u. a. Farbstoffgemische verwendet werden sowie der Leit‐Elektrolyt variiert wird. Insbesondere sind die Experimente zur vertieften Behandlung des Donator‐Akzeptor‐Prinzips geeignet.
Dose intensification of daunorubicin and cytarabine during treatment of adult acute lymphoblastic leukemia
Authors: Stock Wendy , Johnson Jeffrey L. , Stone Richard M. , Kolitz Jonathan E. , Powell Bayard L. , Wetzler Meir , Westervelt Peter , Marcucci Guido , DeAngelo Daniel J. , Vardiman James W. , McDonnell Diane , Mrózek Krzysztof , Bloomfield Clara D. , Larson Richard A. 
Published: June 2012

AbstractBACKGROUND:Cancer and Leukemia Group B (CALGB) Study 19802, a phase 2 study, evaluated whether dose intensification of daunorubicin and cytarabine could improve disease‐free survival (DFS) in adults with acute lymphoblastic leukemia (ALL) and whether high‐dose systemic and intrathecal methotrexate could replace cranial radiotherapy for central nervous system (CNS) prophylaxis.METHODS:One hundred sixty‐one eligible, previously untreated patients ages 16 to 82 years (median age, 40 years) were enrolled, and 33 (20%) were aged ≥60 years.RESULTS:One hundred twenty‐eight patients (80%) achieved complete remission (CR). Dose intensification of daunorubicin and cytarabine was feasible. At a median follow‐up of 10.4 years for surviving patients, the 5‐year DFS rate was 25% (95% confidence interval, 18%‐33%), and the overall survival (OS) rate was 30% (95% confidence interval, 23%‐37%). Patients aged <60 years who received the 80 mg/m2 dose of daunorubicin had a DFS of 33% (95% confidence interval, 22%‐44%) and an OS of 39% (95% confidence interval, 29%‐49%) at 5 years. Eighty‐four patients (52%) relapsed, including 9 patients (6%) who had isolated CNS relapses. The omission of cranial irradiation did not result in higher than historic CNS relapse rates.CONCLUSIONS:Intensive systemic, oral, and intrathecal methotrexate dosing permitted the omission of CNS irradiation in adult patients with ALL. This intensive approach using higher doses of daunorubicin and cytarabine failed to result in an overall improvement in DFS or OS compared with historic CALGB studies. Future therapeutic strategies for adults with ALL should be tailored to specific age and molecular genetic subsets. Cancer 2013. © 2012 American Cancer Society.
Psychosocial service use and unmet need among recently diagnosed adolescent and young adult cancer patients
Authors: Zebrack Brad J. , Block Rebecca , Hayes‐Lattin Brandon , Embry Leanne , Aguilar Christine , Meeske Kathleen A. , Li Yun , Butler Melissa , Cole Steven 
Published: June 2012

AbstractBACKGROUND:Adolescents and young adults (AYAs) with cancer demonstrate biomedical risks and psychosocial issues distinct from those of children or older adults. In this study, the authors examined and compared the extent to which AYAs treated in pediatric or adult oncology settings reported use of, and unmet need for, psychosocial support services.METHODS:Within 4 months of initial cancer diagnosis, 215 AYAs ages 14 to 39 years (99 from pediatric care settings and 116 from adult care settings; 75% response rate) were assessed for reporting use of information resources, emotional support services, and practical support services. Statistical analyses derived odds ratios and 95% confidence intervals for service use and unmet needs after controlling for race, employment/school status, sex, relationship status, severity of cancer, treatment, and treatment‐related side effects.RESULTS:AYAs ages 20 to 29 years were significantly less likely than teens and older patients ages 30 to 39 years to report using professional mental health services and were significantly more likely to report an unmet need with regard to cancer information, infertility information, and diet/nutrition information. Compared with teens who were treated in pediatric facilities, AYAs who were treated in adult facilities were more likely to report an unmet need for age‐appropriate Internet sites, professional mental health services, camp/retreats programs, transportation assistance, and complementary and alternative health services.CONCLUSIONS:Substantial proportions of AYAs are not getting their psychosocial care needs met. Bolstering psychosocial support staff and patient referral to community‐based social service agencies and reputable Internet resources may enhance care and improve quality of life for AYAs. Cancer 2013. © 2012 American Cancer Society.
Phase 1 trial of preoperative, short‐course carbon‐ion radiotherapy for patients with resectable pancreatic cancer
Authors: Shinoto Makoto , Yamada Shigeru , Yasuda Shigeo , Imada Hiroshi , Shioyama Yoshiyuki , Honda Hiroshi , Kamada Tadashi , Tsujii Hirohiko , Saisho Hiromitsu ,   Working Group for Pancreas Cancer
Published: June 2012

AbstractBACKGROUND:The authors evaluated the tolerance and efficacy of carbon‐ion radiotherapy (CIRT) as a short‐course, preoperative treatment and determined the recommended dose needed to reduce the risk of postoperative local recurrence without excess injury to normal tissue.METHODS:Patients radiographically defined with potentially resectable pancreatic cancer were eligible. A preoperative, short‐course, dose‐escalation study was performed with fixed 8 fractions in 2 weeks. The dose of irradiation was increased by 5% increments from 30 grays equivalents (GyE) to 36.8 GyE. Surgery was to be performed 2 to 4 weeks after the completion of CIRT.RESULTS:The study enrolled 26 patients. At the time of restaging after CIRT, disease progression with distant metastasis or refusal ruled out 5 patients from surgery. Twenty‐one of 26 patients (81%) patients underwent surgery. The pattern of initial disease progression was distant metastasis in 17 patients (65%) and regional recurrence in 2 patients (8%). No patients experienced local recurrence. The 5‐year survival rates for all 26 patients and for those who underwent surgery were 42% and 52%, respectively.CONCLUSIONS:Preoperative, short‐course CIRT followed by surgery is feasible and tolerable without unacceptable morbidity. Cancer 2013. © 2012 American Cancer Society.
Improving energy‐efficient communications with a battery lifetime‐aware mechanism in IEEE802.16e wireless networks
Authors: Chou Li‐Der , Li David Chunhu , Hong Wei‐Yong 
Published: June 2012

SUMMARYGreen network communication has recently received attention because of its economic and environmentally friendly benefits. Energy consumption significantly affects mobile subscriber stations in wireless broadband access networks. Efficient energy saving is an important and challenging issue because all mobile stations are powered by limited battery lifetimes. The IEEE 802.16e standard adopts the sleep mode operation for energy saving with three important parameters: idle threshold, initial sleep window and final sleep window. Adaptively adjusting these parameters to improve energy‐efficient communication is an open research topic. This paper proposes a battery lifetime‐aware energy‐saving mechanism to adaptively adjust three sleep mode parameters for mobile stations and extend batteries lives. The new mechanism considers effect factors, including residual battery lifetime and traffic load on mobile stations. Analytical sleep mode operation models were explored in this work. Our proposed mechanism was examined with a computer simulation using QualNet. The simulation results demonstrate that the proposed mechanism outperforms the IEEE 802.16e standard in the average lives of mobile stations, improving them by up to 30.08% with little increase in the average waiting delay. Copyright © 2012 John Wiley & Sons, Ltd.
High‐Amplitude versus Low‐Amplitude Current Oscillations during the Anodic Oxidation of p‐Type Silicon in Fluoride Containing Electrolytes
Authors: Schönleber Konrad , Krischer Katharina 
Published: June 2012

AbstractSustained electrochemical oscillations at p‐type Si(100) in a dilute ammonium fluoride electrolyte are investigated by means of ellipsometric intensity and hydrogen measurements. Two main types of oscillations are identified, one with a low and one with a high current amplitude. It is demonstrated that the low‐current amplitude oscillations do not involve any variations in oxide quality or etch rate. Furthermore, experimental results suggest that the high‐amplitude current oscillations emerge from the low‐amplitude current oscillations and thus share the feedback loops causing the oscillatory instability. Hence, the origin of oscillations during anodic dissolution of silicon has to be reconsidered.
Coprecipitated, Copper‐Based, Alumina‐Stabilized Materials for Carbon Dioxide Capture by Chemical Looping Combustion
Authors: Imtiaz Qasim , Kierzkowska Agnieszka Marta , Müller Christoph Rüdiger 
Published: June 2012

AbstractChemical looping combustion (CLC) has emerged as a carbon dioxide capture and storage (CCS) process to produce a pure stream of CO2 at very low costs when compared with alternative CCS technologies, such as scrubbing with amines. From a thermodynamic point of view, copper oxide is arguably the most promising candidate for the oxygen carrier owing to its exothermic reduction and oxidation reactions and high oxygen‐carrying capacity. However, the low melting point of pure copper of only 1085 °C has so far prohibited the synthesis of copper‐rich oxygen carriers. This paper is concerned with the development of copper‐based and Al2O3‐stabilized oxygen carriers that contain a high mass fraction of CuO, namely, 82.4 wt %. The oxygen carriers were synthesized by using a coprecipitation technique. The synthesized oxygen carriers were characterized in detail with regards to their morphological properties, chemical composition, and surface topography. It was found that both the precipitating agent and the pH at which the precipitation was performed strongly influenced the structure and chemical composition of the oxygen carriers. In addition, XRD analysis confirmed that, for the majority of the precipitation conditions investigated, CuO reacted with Al2O3 to form fully reducible CuAl2O4. The redox characteristics of the synthesized materials were evaluated at 800 °C by using methane as the fuel and air for reoxidation. It was found that the oxygen‐carrying capacity of the synthesized oxygen carriers was strongly influenced by both the precipitating agent and the pH at which the precipitation was performed; however, all oxygen carriers tested showed a stable cyclic oxygen‐carrying capacity. The oxygen carriers synthesized at pH 5.5 using NaOH or Na2CO3 as the precipitating agents were the best oxygen carriers synthesized owing to their high and stable oxygen transfer and uncoupling capacities. The excellent redox characteristics of the best oxygen carrier were interpreted in light of the detailed morphological characterization of the synthesized material and a synthesis–structure–performance relationship was developed.
Consequences of high temperatures and premature mortality on the transcriptome and blood physiology of wild adult sockeye salmon (Oncorhynchus nerka)
Authors: Jeffries Ken M. , Hinch Scott G. , Sierocinski Thomas , Clark Timothy D. , Eliason Erika J. , Donaldson Michael R. , Li Shaorong , Pavlidis Paul , Miller Kristi M. 
Published: June 2012

AbstractElevated river water temperature in the Fraser River, British Columbia, Canada, has been associated with enhanced mortality of adult sockeye salmon (Oncorhynchus nerka) during their upriver migration to spawning grounds. We undertook a study to assess the effects of elevated water temperatures on the gill transcriptome and blood plasma variables in wild‐caught sockeye salmon. Naturally migrating sockeye salmon returning to the Fraser River were collected and held at ecologically relevant temperatures of 14°C and 19°C for seven days, a period representing a significant portion of their upstream migration. After seven days, sockeye salmon held at 19°C stimulated heat shock response genes as well as many genes associated with an immune response when compared with fish held at 14°C. Additionally, fish at 19°C had elevated plasma chloride and lactate, suggestive of a disturbance in osmoregulatory homeostasis and a stress response detectable in the blood plasma. Fish that died prematurely over the course of the holding study were compared with time‐matched surviving fish; the former fish were characterized by an upregulation of several transcription factors associated with apoptosis and downregulation of genes involved in immune function and antioxidant activity. Ornithine decarboxylase (ODC1) was the most significantly upregulated gene in dying salmon, which suggests an association with cellular apoptosis. We hypothesize that the observed decrease in plasma ions and increases in plasma cortisol that occur in dying fish may be linked to the increase in ODC1. By highlighting these underlying physiological mechanisms, this study enhances our understanding of the processes involved in premature mortality and temperature stress in Pacific salmon during migration to spawning grounds.
Observations and conceptual modelling of morphological coupling in a double sandbar system
Authors: Price Timothy D. , Ruessink B. G. 
Published: June 2012

ABSTRACTNearshore sandbars, located in <10 m water depth, can contain remarkably periodic alongshore undulations in both cross‐shore position and depth. In a double sandbar system, the alongshore spacing of these morphological patterns in the inner sandbar may be identical to those in the outer sandbar. Although this morphological coupling has been observed previously, its frequency and predominance remain unclear. In this paper, we use a 9.3‐year dataset of daily low‐tide time exposure images from the double‐barred beach at Surfers Paradise (Gold Coast, Australia) to analyse the temporal and spatial characteristics of morphological coupling within a double sandbar system. We distinguish five types of morphological coupling between the inner and outer sandbars, of which four coincide with a downstate progression of the outer bar. Coupling is either in‐phase (with a landward perturbation of the inner bar facing an outer‐bar horn) or out‐of‐phase (with a seaward perturbation of the inner bar facing an outer‐bar horn), where the coupled inner‐bar features either consist of rip channels or, predominantly, perturbations of the low‐tide terrace. Cross‐correlation of the image‐derived inner‐ and outer‐bar patterns shows coupling to be a common phenomenon in the double sandbar system studied here, with coupling in 40% of the observations. In contrast to previous observations of sandbar–shoreline coupling at single‐barred beaches, in‐phase coupling (85% of all coupled bar patterns) predominates over out‐of‐phase coupling (15%). Based on our observations and bathymetries assimilated from the images for a restricted set of coupling events, we hypothesize that the angle of offshore wave incidence, wave height and depth variations along the outer sandbar determine the type of flow pattern (cell circulations versus meandering currents) above the inner bar and hence steer the type of coupling. Copyright © 2012 John Wiley & Sons, Ltd.
Linking weathering and rock slope instability: non‐linear perspectives
Authors: Viles Heather A. 
Published: June 2012

ABSTRACTWeathering is linked complexly to the erosion and evolution of rock slopes. Weathering influences both the strength of rock slopes and the stresses that act upon them. While weathering has often been portrayed in an over‐simplified way by those studying rock slope instability, in reality it consists of multiple processes, acting over different spatial and temporal scales, with many complex inter‐linkages. Through a demonstration of the sources of non‐linearities in rock slope weathering systems and their implications for rock slope instability, this paper proposes five key linkages worthy of further study. Copyright © 2012 John Wiley & Sons, Ltd.
Numerical flux functions for Reynolds‐averaged Navier–Stokes and kω turbulence model computations with a line‐preconditioned p‐multigrid discontinuous Galerkin solver
Authors: Wallraff Marcel , Leicht Tobias , Lange‐Hegermann Markus 
Published: June 2012

SUMMARYWe present an eigen‐decomposition of the quasi‐linear convective flux formulation of the completely coupled Reynolds‐averaged Navier–Stokes and kω turbulence model equations. Based on these results, we formulate different approximate Riemann solvers that can be used as numerical flux functions in a DG discretization. The effect of the different strategies on the solution accuracy is investigated with numerical examples. The actual computations are performed using a p‐multigrid algorithm. To this end, we formulate a framework with a backward‐Euler smoother in which the linear systems are solved with a general preconditioned Krylov method. We present matrix‐free implementations and memory‐lean line‐Jacobi preconditioners and compare the effects of some parameter choices. In particular, p‐multigrid is found to be less efficient than might be expected from recent findings by other authors. This might be due to the consideration of turbulent flow. Copyright © 2012 John Wiley & Sons, Ltd.
Preparation and Characterization of LiMn2O4 Cathodes Surface‐Modified by DC Pulsed Plasma Treatment
Authors: Chen Cheng‐Lun , Chiu Kuo‐Feng , Chen Yan‐Ru , Lin Hsin‐Chih , Chen Chen Chung 
Published: June 2012

AbstractA study of oxygen dc pulsed plasma irradiation treatment has been carried out on LiMn2O4 powder cathodes to enhance the electrochemical performances of lithium ion batteries. The samples have been characterized by X‐ray diffraction, scanning electron microscope, energy dispersion spectroscope and electrochemical measurements. It is found that after undergoing the plasma treatments, the sharp facets of LiMn2O4 particles become smooth due to plasma ion bombardment. The treated electrodes are partially covered by layers with high atomic percent of element F, indicating the reflow of binders. The electrochemical measurements are carried out under harsh conditions, including deep‐discharge at low cut‐off potential of 2 V and cycling at elevated temperature of 60 °C. The results reveal that moderate oxygen dc pulsed plasma treatment can improve the cycling stability of LiMn2O4 powder electrodes in the above mentioned conditions. The enhanced electrochemical performances are attributed to the dense protection layers on electrode surface, which reduce the capacity fading due to the Mn+2 ions dissolution.