bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the Asymmetric Roll Bonding Process by Means of the Slab Method
Authors: Schouwenaars Rafael , Jacobo Víctor H. , Ortiz Armando
Published: December 2011

In asymmetric roll bonding, two metal sheets with dissimilar properties are subject to a rolling step to create a bimetal strip. The paper reviews earlier work in this field which generally uses the upper-bound or finite element methods. The use of the slab method appears simpler than the former, but allows identifying critical aspects of process and model which were not addressed before. To obtain a complete set of equations, the bonding problem must be analysed not only from the cinematic viewpoint, but also from a mechanical one. After defining mechanical equilibrium, one additional cinematic equation is needed to solve the problem, which is obtained by minimising the plastic work in the zone where both sheets deform plastically but are not yet bonded. The new model has the advantage over earlier approaches in that it not only predicts the final thickness of both sheets but also permits to determine whether the bonding is possible under given process conditions. Keywords: Roll Bonding, Cladding, Modelling, Adhesion, Slab method.
Atomic-Scale Computer Simulation for early Precipitation Process of Ni75AlXV25-X Alloy with Middle Al Composition
Authors: Zhao Yu Hong , Hou Hua , Zhao Yu Hui
Published: December 2011

The microscopic phase field approach was applied for modeling the early precipitation process of Ni75AlxV25-xalloy. Without any a prior assumption, this model can be used to simulate the temporal evolution of arbitrary morphologies and microstructures on atomic scale. Through the simulated atomic pictures, calculated order parameters and volume fraction of the θ (Ni3V) and γ′ (Ni3Al) ordered phases, Ni75AlxV25-xalloys with Al composition of 0.05, 0.053 and 0.055 (atom fraction) were studied. Results show: For these alloys, θ and γ′ precipitated at the same time. With the increase of Al content, the amount of γ′ phase is increasing and that of θ phase is decreasing; the precipitation characteristic of γ′ phase transforms from Non-Classical Nucleation and Growth (NCNG) to Congruent Ordering + Spinodal Decomposition (CO+SD) gradually, otherwise, the precipitation characteristic of θ phase transforms from Congruent Ordering + Spinodal Decomposition (CO+SD) to Non-Classical Nucleation and Growth (NCNG) mechanism gradually. Both θ and γ′ has undergone the transition process of mixture precipitation mechanism with the characteristic of both NCNG and CO+SD mechanism. No incontinuous transition of precipitation mechanism has been found.
Simulation of Residual Stress in Hot Rolled Large Size H-Beams
Authors: Zhu Guo Ming , Kang Yong Lin , Ma Guang Ting
Published: December 2011

The distribution of residual stress in hot rolled large size H-beams is complex due to the uneven temperature distribution on the final rolling cross-sections. In this paper, 3D simulation analysis is conducted on the residual stress field of cooled large H-beams and the transformation of residual stress field during the flange cutting based on the calculations of thermo-mechanical coupling whole rolling process. There are tensile stress in the flange and web connection areas and compressive stress in web. During the flange cutting process, tensile stress increases suddenly when the kerf arrives at the flange and web connection area, resulting in the brittle fracture of the web. The method of controlling the residual stress of large H-beams is also simulated. Improvement in the distribution of residual stress is achieved through the forced cooling of the outside flange or reduction of the temperature differences on the final rolling cross-sections.
Study on Manufacturing Process and Applying of Galvalume
Authors: Song Meng , Feng Yun Li , Yang Jing Bo
Published: December 2011

Annealing and dip galvanizing treatments of Galvalume were studied by using methods of Gleeble thermal simulation experiment and optical microscopy (OM), scanning electronic microscopy (SEM), X-ray energy dispersive analysis (EDAX), X-ray diffraction (XRD) and so on. Meanwhile, surface morphology, microstructure, phases and the respective compositions of Al-Zn alloy coating plate were analyzed. The results show that decreased rate and prolonged time of annealing treatment cause less effect on process ability of product, which all because of the short time of annealing process in continuous aluminum-zinc treatment. However, coarse grain which causes low strength, high elongation and r value occurs when rising annealing temperature. To get better coated surface, in-zinc pot temperature should be controlled in the range of 590~610°C, and height of air-knife nozzle should be kept in the range of 150~200mm. Surface layer of 55％Al-Zn alloy coating is covered by Al-Zn alloy, the intermediate alloy layer is consisted of binary and ternary compounds, such as θ phase (FeAl3), Al0.3Fe3Si0.7 and Al3.21Si0.47. Keywords: Galvalume, Process, Microstructure, Properties
Numerical Simulation on Spinning Forming Process of Automotive Wheel Rim
Authors: Bi Da Sen , Yang Guang , Chu Liang , Zhang Jian , Wang Zhi Hua
Published: December 2011

In this paper, the spinning process of automotive wheel rim is simulated with the finite element software DEFORM-3D. The forming of the automotive wheel rim based on finite element method is completed by the improvement of the spinning process. it can be divided into three different stages: spinning stage, flattening stage and shaping stage. The reference data for technological parameter of spinning process is achieved.The results are useful to the further research of the spinning process of automotive wheel rim.
Flow Stress Behavior of Al-Fe-V-Si Heat-Resistant Aluminum Alloy Prepared by Spray Forming under Hot-Compression Deformation
Authors: Zhang Ronɡ Hua , Zhang Yon Gan , Zhu Bao Hong
Published: December 2011

The behavior of the flow stress of Al-Fe-V-Si heat-resistant aluminum alloy prepared by spray forming during hot compression deformation was studied. The results show that the true stress-true strain curves of the spray forming Al-Fe-V-Si heat-resistant alloy are characterized by a high true stress occurrence at the early stage of compression, followed by a steady flowing due to recovery and strain softening because of dynamic recrystallization. The flow stress of the alloy decreases with increasing deforming temperature and increases with increasing strain rate. The flow stress of the spray forming Al-Fe-V-Si heat-resistant aluminum alloy during hot compression deforming can be described by constitutive equation in hyperbolic sine function．The deformation activation energy of the alloy during hot deformation by Sellars-Tegart equation is much higher than those of the conventional aluminum alloy. The deformation activation energy decreases with decreasing strain rate at the beginning, then increases with decreasing strain rate. Keywords：Al-Fe-V-Si alloy；heat-resistant aluminum alloy；hot compression deformation；flow stress
Research on Quartz Flat Mirror’s Thermal Deformation under the Condition of Non Uniform Heating
Authors: Dai Suian , Chang Sheng Li , Lan Yong , Luo Jian Feng , Wang Fei
Published: December 2011

The optical system used in aerospace works under a very difficult aerospace condition. The temperature difference between the sides which one is facing the sun and the other one is opposite the sun can reach about 200°C. These temperature grids can bring thermal deformation to the optical components and then influence the whole system’s image or detect results. To measure and analysis the deformation, we first use finite element method to establish a heat exchange model with definite temperature boundary condition to simulate the thermal distribution situation of an optical mirror, and then we establish a laboratory experimental environment and use the thermal imager to measure the temperature distribution on the surface of the mirror and use Zygo GPI XP-D/1000 interferometer to measure the thermal deformation, from the experimental results, we can see that the definite temperature boundary condition is good enough. And the definite flow boundary condition is not necessary under this non uniform heating situation. Key Words: thermal deformation, finite element model, non uniform heating
Die Forging Process Simulation of a Connecting Rod
Authors: Xu Lei , Dai Guang Ze , Huang Xing Ming , Han Jing , Zhao Jun Wen
Published: December 2011

Numerical simulation of connecting rod die forging processing was performed by finite element method (FEM) software Deform 3D. The changes of the temperature fields, stress fields of the billet and dies, and upper setting force-stroke curve during the die forging were obtained. The simulation results show that (1) the increase of the fillet radius of dies could effectively reduce the stress concentration so that to prevent the die crack arising at high level stress; (2) the optimum parameters of die forging process are 430°C for forging temperature, 200°C for preheat temperature of dies and 80mm/s for reduction rate by comparing both fields of the stress and temperature during different forging process..
The Effect of Heat Treatment on Mechanical and Corrosion Performances of Zr-Nb Alloy
Authors: Yang Xiao Lei , Deng De Wei , Wang Yong , Ge Yan Liu
Published: December 2011

The mechanical performance and corrosion resistance of Zr-Nb alloy (Zr705) treated in different ways is tested, and it is found that those properties of Zr-Nb alloy are significantly affected by heat treatment. The most important parameter of the heat treatment is quenching temperature. The Zr-Nb alloy, quenched below the critical quenching temperature Tcq (a temperature or a range of temperature between 850°C-870°C) presents good corrosion resistance performance, however, quenched above the Tcq gets a higher strength and a lower corrosion resistance. Through the study on the basis of the evidences gotten by means of metallographic, SEM, EPMA and TEM, the conclusion can be drawn as that the effect of heat treatment on the performances of Zr-Nb alloy is primarily because of the mechanism of the distribution change of Nb, the quantity of β-Zr, the morphology of grains. Keywords: Zr-Nb alloy, heat treatment, β-Zr, twins
High Concentration of Viscous Material Pipeline Characteristics of the Discussion
Authors: Yu Zhi Fu , Tian Xiao Li , Pan Yue
Published: December 2011

The high concentration of different rheological properties of viscous materials determines the properties of the material advantages and disadvantages of piped varying degrees, this article in order to slime represented by a variety of high concentration of viscous test material for pipeline transportation, according to pipeline pressure loss of various materials to determine rheological characteristics of pipeline transportation, obtained pipeline flow equation, and then determine the delivery pressure, flow, length of experience in relationship, through the material and the wall friction and power calculation To further determine the energy loss of control resistance laid the basis for optimal design of transportation systems. Key words: viscous materials, sensing devices, pressure testing, pressure distribution, pressure drop
Predicted Model of Section Stress Distribution and Bending Strength of Fiberboard Based on Vertical Density Profile
Authors: Zhang Yang , Yu Zhi Ming
Published: December 2011

To study the impact of VDP on the bending process of fiberboard, this paper deeply researched into the dynamic changes of section stress distribution of fiberboard during the process of loading and bending and built a static bending strength predicting model, which is based on the piecewise function by simulating fiberboard VDP, theory of elasticity and plasticity, lamella inter-bedded theory and VDP model. The results show: The bending process of fiberboard can be divided into two stages which are elasticity period and elasticity-plasticity period. The latter includes both elasticity region and plasticity region, and compression region comes to elasticity bending before pulling region. The curve of bending section stress distribution is nonlinear and affected by loads and VDP. Critical section stress distribution of bending breakage and breakage load can be predicted by VDP with other condition unchanged. The value of static bending strength predicted by model is basically consistent with testing data. And the static bending strength is closely related to qualification factors of VDP. Fiberboard with high average density doesn’t always contain high static bending strength. VDP is a significant physical parameter which has impact on the bending process and performance of fiberboard, so it must be optimized and controlled in production according to for specific purpose. Key words: fiberboard, vertical density profile, section stress distribution, bending strength, predicting model
Phase Relationships in the Y–Fe–V Ternary System at 773 K
Authors: Pan Shun Kang , Yan Rui , Zhou Huai Ying , Cheng Li Chun , Yao Qing Rong , Zhong Yan
Published: December 2011

The isothermal section of the phase diagram of the ternary system Y–Fe–V at 773 K was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. It consists of 9 single-phase regions, 16 two-phase regions and 8 three-phase regions. The ternary compound YFe12-xVx(1.5≤x≤2.7, space groupI4/mmm) with Mn12Th-type structure was confirmed in this system. At 773 K, the maximum solid solubility of V in Fe, and YFe2, is about 23 at.%, and 3 at.%, respectively, Fe in V is about 22 at.%. And that of Y in Fe, FeV and V don′t exceed 1 at.%.
First-Principle Calculations of the Electronic Structure and Elastic Constants of Arsenic Doped β-SiC
Authors: Wang Zong Guo , Hui Qun , Cheng Nan Pu , Wang Chui Lin
Published: December 2011

The electronic structure and elastic constants of arsenic doped β-SiC have been studied by first principles density functional theory (DFT) calculations. The band structure, bulk modulus, and density of states were calculated. We have demonstrated that both the top of the valence and the bottom of the conduction band shift to lower energy levels. However, arsenic doped β-SiC exhibits a non-monotonic variation of the band gap and bulk modulus with the concentration of As. Keywords: arsenic doped β-SiC, electronic structure, elastic constant, first principles
Water Inrush Monitoring of Zhangmatun Mine Grout Curtain and Seepage-Stress-Damage Research
Authors: Chen Shi Kuo , Yang Tian Hong , Liu Hong Lei , Zhu Wan Cheng
Published: December 2011

Based on extensive literature review, the state of the art of coupled hydromechanical models and in-situ monitoring for groundwater inrush predictions are summarized in detail, based on which, it is proposed that the key issues for describing the seepage characteristics during groundwater inrush are to calibrate the equations for damage-induced evolution of permeability and of effective stress. Depending on in-situ experiments and numerical simulations, a new academic idea, i.e.“the rock micro seismicity induced by mining processes and water pressure disturbance is in essence the index of groundwater inrush” is put forward based on case studies, coupled hydro-mechanical theory, high-performance computing technology and microseismic monitoring. The authors propose that the tendency for analyzing and predicting the groundwater inrush is to synthetically inverse the inrush pathway formation, strata microseismic precursor and high performance computing results. And relying on the microseismic monitoring events, the groundwater inrush models are calibrated, which could be used to clarify the precursory characteristics and to locate the inrush pathway. This study will lay theoretical basis for establishing the models to predict the groundwater inrush in underground mining. Key words：rock mechanics, groundwater inrush models, calibrating, numerical simulation, microseismic monitoring
The Coupled Thermal Mechanical Modeling of the Inertia Friction Welding Process for Inconel718
Authors: Bu Wen De , Liu Jin He
Published: December 2011

In this paper, numerical modeling of inertia friction welding (IFW) for Inconel718 was performed using ABAQUS/Explicit with a 3D finite-element (FE) model and the coupled thermo-mechanical analysis. A new thermal input model has been deduced according to the characteristics of IFW and law of conservation of energy. The evolution of temperature field as well as the deformation pattern of the inertia welded joint has been predicted. It is shown that the interface temperature firstly increases rapidly to about 1100 °C within 3 s and then increases slowly. The energy input rate at the interface during the IFW process is closely related to the rotational speed and friction torque of flywheels. The temperature distribution at the interface is very inhomogeneous especially at the initial stage and finally tends to become uniform with the increase of time. Consequently, the flash start to appear as the interface temperature becomes homogeneous relatively and the plastic flow of metal at the interface happens. The verifying trial was carried out and the predicted temperature was compared with the experimental data measured by means of thermocouples. The shape of flash in simulation result was contrasted with the true shape of specimen under the same welding conditions. It is noted that the simulation results agrees well with the experimental results.
The Computer Solidification Simulation and Process Optimization of Gear Ring
Authors: Wang Ai Qin , Xie Jing Pei , Wang Wen Yan , Li Ji Wen
Published: December 2011

The numerical solidification simulation for gear ring steel casting has been made, and the location and reasons forming casting defects have been predicted by HUAZHU CAE software. Simulating result shows that the directional solidification and efficient feeding were maintained and the casting perfects can be realized by means of the computer simulation optimizing technological and rationally design of gating system, insulated risers, iron chill and compensating efficiently. After magnetic particle detection and ultrasonic inspection, the properties and microstructure of the Gear ring steel casting are in accord with the international standard.
Simulation Study of Hydraulic Fracturing Mechanism with Heterogeneous Material
Authors: Yang Tian Hong , Liu Hong Lei , Yu Qing Lei , Chen Shi Kuo
Published: December 2011

first of all, this paper intensive studies the hydraulic fracturing mechanism of heterogeneous material resultant from the seepage – damage coupling, based on which, the coupled seepage and damage effects during hydraulic fracturing is investigated, and the difficulties of hydraulic fracturing study are how to determine failure modes and breakdown pressure. By using numerically testing method, the mechanical mechanism of hydraulic fracturing under asymmetric distribution of pore pressure with three holes, including fracture patterns, stress flied distribution, initial fracturing pressure and breakdown pressure, was studied by using theFSDmodel. According to the results of this research, crack extension direction of hydraulic fracturing is influenced not only by the local pore pressure around crack tip, but also by the gradient distribution of macro pore water pressure. The fracturing direction always propagates towards the regions of higher local pore pressure and breakdown pressure decreases with the increasing of local pore pressure. These results are well aggress with the results in the experiments. This research has important theoretical and engineering value. In engineering practice, we can use the porous asymmetric hydraulic fracturing technology to control the direction of crack propagation. Keywords: hydraulic fracturing; numerical simulation; heterogeneous material; asymmetrical
New Insights on OX40 in the Control of T Cell Immunity and Immune Tolerance In Vivo
Authors: Xiao Xiang , Gong Weihua , Demirci Gulcin , Liu Wentao , Spoerl Silvia , Chu Xiufeng , Bishop D. Keith , Turka Laurence A. , Li Xian C.
Published: December 2011

OX40 is a T cell costimulatory molecule that belongs to the TNFR superfamily. In the absence of immune activation, OX40 is selectively expressed by Foxp3+ regulatory T cells (Tregs), but not by resting conventional T cells. The exact role of OX40 in Treg homeostasis and function remains incompletely defined. In this study, we demonstrate that OX40 engagement in vivo in naive mice induces initial expansion of Foxp3+ Tregs, but the expanded Tregs have poor suppressive function and exhibit features of exhaustion. We also show that OX40 enables the activation of the Akt and Stat5 pathways in Tregs, resulting in transient proliferation of Tregs and reduced levels of Foxp3 expression. This creates a state of relative IL-2 deficiency in naive mice that further impacts Tregs. This exhausted Treg phenotype can be prevented by exogenous IL-2, as both OX40 and IL-2 agonists drive further expansion of Tregs in vivo. Importantly, Tregs expanded by both OX40 and IL-2 agonists are potent suppressor cells, and in a heart transplant model, they promote long-term allograft survival. Our data reveal a novel role for OX40 in promoting immune tolerance and may have important clinical implications.
Voornemende Wiskunde-onderwysers se metakognitiewe vaardighede tydens lesstudie in mikro-onderrig (MLS)
Authors: Van der Walt Marthie S.
Published: December 2011

Die moontlikhede wat metakognitiewe vaardighede in onderrig en leer vir die verbetering van onderrig en leer in Wiskunde inhou, is relatief onbekend aan Suid-Afrikaanse onderwysers en leerders. Die skoolkurrikulum maak nie eksplisiet voorsiening vir die fasilitering van hierdie vaardighede nie. In ’n onderwysersopleidingsinisiatief waaroor daar in hierdie artikel gerapporteer word, is voornemende laerskool Wiskunde-onderwysers in een van hul vierdejaarmetodiek-modules aan lesstudie in mikro-onderrig (MLS) bekendgestel. Die doel van die ondersoek was om die ontplooiing en toepassing van ’n metakognitiewe praktykbenadering tot MLS te ondersoek, asook om voornemende onderwysers se kennis te ontwikkel rakende hul eie onderrig van meting, vorm en ruimte, hul leerders se leer daarvan en hul kennis van die inhoud van die Wiskundekurrikulum oor grade en fases. Die data in hierdie kwalitatiewe gevallestudie is tydens klas- en groepbesprekings (beplanning), aanbiedings van en die geskrewe MLS, asook uit metakognitiewe refleksieverslae bekom. Data is georden en deurgelees, en daarna is kodes aan betekenisvolle woorde of frases toegeken. Deur sodanige ontleding is die unieke eienskappe en struktuur van die data blootgelê sodat dit beskryf, geïnterpreteer en verduidelik kon word (Nieuwenhuis 2007). Uit die resultate blyk dit dat die MLS-ervarings bygedra het tot die groep se verbeterde metakognitiewe kennis en vaardighede.
Quantum Limits of Eisenstein Series and Scattering States
Authors: Petridis Yiannis N. , Raulf Nicole , Risager Morten S.
Published: December 2011

We identify the quantum limits of scattering states for the modular surface. This is obtained through the study of quantum measures of non-holomorphic Eisenstein series away from the critical line. We provide a range of stability for the quantum unique ergodicity theorem of Luo and Sarnak.
Ecosystem response to a salmon disturbance regime: Implications for downstream nutrient fluxes in aquatic systems
Authors: Albers Sam J. , Petticrew Ellen L.
Published: December 2011

Recent work in salmon spawning streams has shown that sediment resuspended during nest construction flocculates with salmon organic matter to form suspended composite particles characterized by increased size and settling velocities. In a river system, these flocs have the potential to interact with benthic biofilms, suggesting a mechanism for the incorporation of organic matter into aquatic food webs. Using the Horsefly River spawning channel in central British Columbia, the spatial scale of biofilm floc trapping was evaluated for a salmon disturbance regime, which consists of the active digging of redds, spawning, and carcass decay. We stocked two sequential enclosures in the spawning channel with sockeye salmon (Oncorhynchus nerka) and established one upstream control enclosure. Biofilms were sampled for chlorophyll a, trapped sediment, and marine isotope tracers (δ15N and δ13C). In the active‐spawn period, biofilm abundance was reduced due to spawning disturbance, with isotope values indicating low utilization of marine‐derived nutrients (MDNs). During the post‐spawn period, downstream biofilm abundance exceeded pre‐spawn values, indicating a near‐field nutrient pulse with isotope values reflecting biofilm utilization of MDNs. At the same time, an increase in biofilm trapping efficiency occurred in concert with a significant increase in the in situ particle size of suspended sediment, suggesting that flocs were a temporary storage site of MDNs. The retention of MDNs over short spatial scales acts to retard the flushing of MDNs to downstream rearing lakes. The magnitude of these processes has ecological implications on the downstream lake's productivity, thereby influencing the success of future salmon stocks.
High‐resolution surveys of internal tidal waves in Monterey Bay, California, using an autonomous underwater vehicle
Authors: Cazenave François , Zhang Yanwu , McPhee‐Shaw Erika , Bellingham James G. , Stanton Timothy P.
Published: December 2011

Temperature measured at the Monterey Inner Shelf Observatory (MISO) in southern Monterey Bay reveals frequent solitons and semidiurnal internal tidal bores (ITBs). A field study was undertaken to determine whether these features originate offshore and propagate shoreward over the continental shelf, and to characterize their evolution as they propagate. We developed a new survey method of using an autonomous underwater vehicle (AUV) to tightly track the thermocline along a 4.5 km transect, repeated 18 times over 18 hours, thereby measuring the internal‐wave induced isotherm displacement at very high resolution. AUV measurements were compared with measurements at MISO, which is closer to shore. Internal waves of various scales were captured. An ITB of amplitude greater than 20 m propagating shoreward from the outer bay was the dominant feature. Rapid changes in stratification, possibly due to horizontal advection, were also observed. Technical challenges, advantages, and future improvements of this new AUV survey method are discussed. This study demonstrates that AUVs are efficient tools for surveying internal tidal waves.
Postambulatory Hand Swelling (Big Hand Syndrome): Prevalence, Demographics, and Association with Dog Walking
Authors: Ravaglia Fabio F. A. , Leite M. Goretti , Bracellos Tiago F. , Cliquet Alberto
Published: December 2011

Introduction. Postambulatory hand swelling (PAHS) seems to be common in the general population. There are few mention in the medical literature. The objective were (1) to identify prevalence; (2) to compare gender and age groups; (3) to determine if dog owners and walkers are more or less prone. Materials and Methods. 1009 semirandomly surveys were completed from walkers. Age, gender, and dog ownership were assessed. We discussed, among dog owners, whether or not they walk their dog regularly, whether or not they notice swollen hands after walking, and, if so, if the swelling resolves over 24 hours or persists. Results. 699 females and 410 males, among whom, 28.9% of females but only 16.3% of males reported PAHS (P<0.001). Surprisingly, those with swelling were statistically younger than those without (49.2 versus 52.8 years, P=0.003), and dog owners were more likely than nonowners to report swelling (28.1% versus 21.7%; P=0.015). In terms of persistent swelling, this was observed in twice the percentage of females as males (13.3 versus 6.5%) and tended to involve older subjects (54.0 versus 48.8 years), but with no statistical difference significance. Conclusions. PAHS is a relatively common phenomenon, seemingly more common in females.
Interactions Between Amino Acid‐Tagged Naphthalenediimide and Single Walled Carbon Nanotubes for the Design and Construction of New Bioimaging Probes
Authors: Hu Zhiyuan , Pantoş G. Dan , Kuganathan Navaratnarajah , Arrowsmith Rory L. , Jacobs Robert M. J. , Kociok‐Köhn Gabriele , O'Byrne Justin , Jurkschat Kerstin , Burgos Pierre , Tyrrell Rex M. , Botchway Stan W. , Sanders Jeremy K. M. , Pascu Sofia I.
Published: December 2011

A new synthetic route to functionalized single walled carbon nanotubes (SWNTs) via supramolecular interactions using a specifically designed naphthalenediimide (NDI) nanoreceptor is demonstrated. The tendency of the NDI to spontaneously form composites with carbon nanomaterials leads to fluorescent amino acid tagged SWNTs, which are dispersible in widely accessible organic solvents (CHCl3, DMSO) as well as in biocompatible cell medium (EMEM, Eagle's modified essential medium). The X‐ray crystal structure of the first iodine‐tagged and amino acid‐functionalized NDI molecule, designed especially to facilitate the high resolution transmission electron microscopy (HR TEM) imaging whilst retaining its ability to self‐assemble into a nanodimensional receptor in weakly polar solvents, is also described. A new hybrid material, NDI@SWNT, was prepared and characterized as dispersed in organic solvents and aqueous media and in the solid state by HR TEM, tapping mode atomic force microscopy (TM AFM), scanning electron microscopy (SEM), circular dichroism, Raman and fluorescence spectroscopies (steady‐state single and two‐photon techniques). Combined microscopy techniques, density functional theory (DFT) calculations using the Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA) program and spectroscopic measurements in solution indicate that amino acid‐functionalized NDI interacts strongly with SWNTs and forms a donor‐acceptor complex. Density functional theory (DFT) calculations predicted the geometry and the binding energies of an NDI molecule loaded onto a SWNT strand and the possibility of charge transfer interactions within the hybrid. The NDI@SWNT composite translocates into cells (e.g. FEK‐4, HeLa, MCF‐7) as an intact object and localizes in the cells' cytoplasm and partially in the nucleus. The NDI coating enhances the biocompatibility of SWNTs and mediates its intracellular localization as shown by confocal fluorescence imaging and fluorescence lifetime imaging (FLIM) techniques. The excited state fluorescence lifetime of the probes in cells versus solution phase indicates that the probes remain unaffected by the change in their chemical environment within the experimental timescale (2 h).
Retracted: Copper‐Catalyzed Cascade Reaction for Practical and Efficient Synthesis of Alkyl 2H‐Isoindole‐1‐carboxylates
Authors: Biswas Subhasish , Nayak Maloy , Kanojiya Sanjeev , Batra Sanjay
Published: December 2011

The copper‐catalyzed cascade reaction comprising the condensation/α‐arylation between 2‐halobenzaldehydes and α‐amino acid esters provides a straightforward methodology for the efficient synthesis of alkyl 2H‐isoindole‐1‐carboxylates.
A Tin‐Free, Radical Photocatalyzed Addition to Vinyl Sulfones
Authors: Ravelli Davide , Montanaro Sara , Zema Michele , Fagnoni Maurizio , Albini Angelo
Published: December 2011

Radical conjugate addition onto vinyl sulfones was achieved by means of a convenient, tin‐free procedure. This was based on the photocatalyzed CH bond activation in aldehydes, amides, ethers and even cycloalkanes by using tetrabutylammonium decatungstate (TBADT). The reaction was likewise effective for the functionalization of β‐substituted vinyl sulfones. The products are useful building blocks and were obtained in satisfactory yields both under artificial UV light and under sunlight, so demonstrating the “green” potential of the process.
Mechanistic Studies into Metal‐Catalyzed Aldoxime to Amide Rearrangements
Authors: Allen C. Liana , Lawrence Ruth , Emmett Liam , Williams Jonathan M. J.
Published: December 2011

The metal‐catalyzed rearrangement of aldoximes into primary amides is a completely atom economical synthetic method for the preparation of one of the most important functional groups in chemistry. There have been several reports of various metals successfully catalyzing this reaction, however, there are conflicting views as to the mechanism involved. Herein we report new experimental evidence to support the mechanism and whether this is universal to all catalysts reported or metal specific. We also describe our further studies into the mechanism of the nickel‐catalyzed acylation of amines with aldoximes.
Secondary Metabolite Profile in Induced Tetraploids of Wild Solanum commersoniiDun.
Authors: Caruso Immacolata , Lepore Laura , De Tommasi Nunziatina , Dal Piaz Fabrizio , Frusciante Luigi , Aversano Riccardo , Garramone Raffaele , Carputo Domenico
Published: December 2011

The main aim of this work was to study the leaf secondary metabolite profiles of artificially induced tetraploids (2n=4x=48) of Solanum commersonii, a diploid (2n=2x=24) wild potato species. The tetraploid genotypes of S. commersonii were produced by oryzalin treatment. Both HPLC‐UV and LC/MS analyses revealed that there were no qualitative differences in the metabolite profiles between the diploid S. commersonii and its tetraploids. By contrast, the results showed that the phenylpropanoid content was generally significantly higher in the tetraploids than in the diploid S. commersonii. Concerning the glycoalkaloids (GAs), the results provided evidence that the content of minor GAs (solanidenediol triose, solanidadienol lycotetraose, and solanidenol lycotetraose) was higher in tetraploids than in the diploid progenitor, while the content of major GAs (dehydrodemissine and dehydrocommersonine) was significantly higher in diploid S. commersonii than in its tetraploid genotypes. The results are discussed from the practical perspective of potato biodiversity enhancement.
Bleeding complications in primary percutaneous coronary intervention of ST‐elevation myocardial infarction in a radial center
Authors: Barthélémy Olivier , Silvain Johanne , Brieger David , Mercadier Anne , Lancar Remi , Bellemain‐Appaix Anne , Beygui Farzin , Collet Jean Philippe , Costagliola Dominique , Montalescot Gilles
Published: December 2011

Objectives: We evaluated the incidence, types, and prognostic impact of bleeding complications in a non‐selected patient population with ongoing STEMI treated with aggressive antithrombotic treatment and routine radial primary PCI. Background: Bleeding complications remain frequent and deleterious in primary PCI through femoral approach. Methods: STEMI patients (n = 671) were evaluated for bleeding complications using a web‐based registry (e‐PARIS). In‐hospital bleeding was adjudicated using the TIMI definition. Results: In this non‐selected, high risk population, 6.1% had cardiogenic shock on admission, 3.9% out‐of‐hospital cardiac arrest. Radial access (88%) was the default strategy as was abciximab (78%). Clopidogrel loading dose ranged from 300 to 900 mg. Pre‐hospital fibrinolysis was rare (7.1%). Hemodynamic support devices (IABP, ECMO, Tandem Heart) were needed in 7.0%. In‐hospital TIMI Major and TIMI Major/minor bleedings occurred in 2.5 and 5.7% of the population, respectively. In‐hospital and 1‐year mortality rates were 5.5 and 8.2%, respectively. Patients with in‐hospital TIMI Major/minor bleeding had a higher 1‐year mortality rate (31.6% vs. 3.8%, P < 0.001). The most frequent bleeding site was gastro‐intestinal. Radial access was a strong predictor of survival (OR 0.33; 95%CI 0.17–0.56; P = 0.002). Conclusions: In the setting of radial primary PCI, the rates and types of bleeding complications are somewhat different from those observed with femoral primary PCI. The gastro‐intestinal tract has become the most frequent site of bleeding after radial primary PCI. The use of radial access appears independently associated with survival. © 2011 Wiley Periodicals, Inc
Detached tip of a transseptal sheath during left atrial ablation
Authors: El‐Damaty Ahmed , Love Michael , Parkash Ratika
Published: December 2011

Left atrial ablation has become more commonplace with the advent of catheter ablation for atrial fibrillation. A number of transseptal sheaths have been produced to enhance safe and efficient catheter manipulation in the left atrium (LA) for these procedures. Some of the sheaths have been subject to recall due to partial or complete detachment of its radiopaque tip. We report a case of a 46 year‐old female diagnosed with idiopathic dilated cardiomyopathy that presented with atypical left atrial flutter. During electrophysiologic study, a Swartz braided SL1 (SL‐1) transseptal sheath was used to introduce the ablation catheter to the left atrium. During left atrial mapping, the radiopaque tip of the sheath detached from the rest of the sheath and was seen floating in the LA. After exchanging the SL‐1 sheath with a deflectable sheath, the detached segment was retrieved out of the LA and eventually out of the vascular system using an angioplasty balloon advanced over a wire and inflated distal to the lumen of the detached tip. The root cause of this malfunction was found to be lack of a secondary bonding process that these sheaths generally undergo during the manufacturing process. We describe the case of a left atrial ablation procedure where a novel percutaneous method was able to successfully retrieve the detached tip of a transseptal sheath from the vascular system, thereby avoiding a potential catastrophic complication or thoracotomy. This method may be useful in other cases where similar circumstances may present. © 2011 Wiley Periodicals, Inc.
StarClose® vascular closure system (VCS) is safe and effective in patients who ambulate early following successful femoral artery access closure—results from the RISE clinical trial
Authors: Burke M. Nicholas , Hermiller James , Jaff Michael R.
Published: December 2011

Objective: The RISE study was a prospective, multicenter, single‐arm study evaluating the safety and efficacy of the StarClose® Vascular Closure System (VCS) in the femoral artery in subjects who were ambulated early following percutaneous diagnostic coronary or peripheral catheterization procedures. Background: Previous studies have demonstrated that several vascular closure devices are able to safely decrease the amount of bedrest needed following angiography. To date, no device has been shown to be safe for immediate ambulation. Methods: Between April 2006 and November 2006, 315 patients undergoing a catheterization via the femoral artery were enrolled (intent‐to‐treat population, ITT). Of these, 171 subjects were not excluded by angiographic or clinical criteria and had a StarClose device placed to attain hemostasis. If hemostasis was immediately achieved, patients were ambulated within 20 min for 20 feet without assistance (per‐protocol population, PP). Patients were followed for 30 days after the index procedure. The primary endpoint of the study was time to ambulation (TTA). Results: Immediate hemostasis was achieved in 156 patients (91.2%). The mean TTA in the PP was 8.29 min, median 5.92. There were no deaths or major vascular complications, and the rate of minor vascular complications was 1.9% (3/156). Conclusion: The StarClose® VCS device is both safe and effective allowing immediate ambulation of patients who have undergone catheterization via the femoral artery. © 2011 Wiley Periodicals, Inc.
Nucleophilic Reactivities of the Anions of Nucleobases and Their Subunits
Authors: Breugst Martin , Corral Bautista Francisco , Mayr Herbert
Published: December 2011

The kinetics of the reactions of different heterocyclic anions derived from imidazoles, purines, pyrimidines, and related compounds with benzhydrylium ions and structurally related quinone methides have been studied in DMSO and water. The second‐order rate constants (log k2) correlated linearly with the electrophilicity parameters E of the electrophiles according to the correlation log k2 = sN(N+E) (H. Mayr, M. Patz, Angew. Chem. 1994, 106, 990–1010; Angew. Chem. Int. Ed. Engl. 1994, 33, 938–957) allowing us to determine the nucleophilicity parameters N and sN for these anions. In DMSO, the reactivities of these heterocyclic anions vary by more than six orders of magnitude and are comparable to carbanions, amide and imide anions, or amines. The azole anions are generally four to five orders of magnitude more reactive than their conjugate acids.
Short Gold Nanorod Growth Revisited: The Critical Role of the Bromide Counterion
Authors: Si Satyabrata , Leduc Cecile , Delville Marie‐Hélène , Lounis Brahim
Published: December 2011

A one‐step, surfactant‐assisted, seed‐mediated method has been utilized for the growth of short gold nanorods with reasonable yield by modifying an established synthesis protocol. Among the various parameters that influence nanorod growth, the impact of the bromide counterion has been closely scrutinized. During this study it has been shown that, irrespective of its origin, the bromide counterion [cetyltrimethylammonium bromide (CTAB) or NaBr] plays a crucial role in the formation of nanorods in the sense that there is a critical [Br−]/[Au3+] ratio (around 200) to achieve nanorods with a maximum aspect ratio. Beyond this value, bromide can be considered as a poisoning agent unless shorter nanorods are required. The use of AgNO3 helps in symmetry breaking for gold nanorod growth, whereas the bromide counterion controls the growth kinetics by selective adsorption on the facets of the growth direction. Thus, a proper balance between bromide ions and gold cations is also one of the necessary parameters for controlling the size of the gold nanorods; this has been discussed thoroughly. The results have been discussed based on their absorption spectra and finally shape evolution has been confirmed by TEM. Due to their efficient absorption in the near‐IR region, these short nanorods were used in photothermal imaging of living COS‐7 cells with improved signal‐to‐background ratios.
Ionization of Methane Clusters in Helium Nanodroplets
Authors: Leidlmair Christian , Bartl Peter , Schöbel Harald , Denifl Stephan , Yang Shengfu , Ellis Andrew M. , Scheier Paul
Published: December 2011

The electron ionization of helium droplets doped with methane clusters is investigated for the first time using high‐resolution mass spectrometry. The dominant ion products ejected into the gas phase are the unprotonated (CH4)n+ cluster ions along with the protonated ions, CH5+(CH4)n−1. The mass spectra show clear evidence for magic numbers, which are broadly consistent with icosahedral shell closings. However, unusual features were observed, including different magic numbers for CH5+(CH4)n−1 (n=55, 148) when compared to (CH4)n+ (n=54, 147). Possible interpretations for some of these differences are proposed. Products of the type [C2Hx(CH4)n]+, which result from ion–molecule chemistry, are also observed and these too show clear magic number features. Finally, we report the first observation of (CH4)n2+ dications from methane clusters. The threshold for dication survival occurs at n≥70 and is in good agreement with a liquid droplet model for fission of multiply charged ions. Furthermore, we present evidence showing that these dications are formed by an unusual two‐step mechanism which is initiated by charge transfer to generate a monocation and is then followed by Penning ionization to generate a dication.
Synthesis and Structural Characterization of Zinc Complexes that Contain Chelating Phenolate Phosphane Ligands
Authors: Liang Lan‐Chang , Shih Huan‐Yu , Chen Han‐Sheng , Lin Sheng‐Ta
Published: December 2011

The preparation and characterization of zinc complexes supported by potentially tridentate biphenolate phosphane ligands are reported. The in situ prepared dilithium complexes of 2,2′‐tert‐butylphosphanylbis(4,6‐di‐tert‐butylphenolate) ([LtBu]2–) and 2,2′‐phenylphosphanylbis(4,6‐di‐tert‐butylphenolate) ([LPh]2–) react with ZnCl2 in tetrahydrofuran (THF) to produce lithium zincates Zn[LtBuLi(THF)]2 and Zn[LPhLi(THF)]2, respectively, regardless of the stoichiometry of the starting materials. Alkane elimination reactions of ZnEt2 with one equiv. of H2LtBu or H2LPh in THF generate Zn2(LtBu)2(THF) or Zn2(LPh)2(THF)2, whereas those employing two equiv. of the protio ligands afford Zn(LtBuH)2(MeCN) or Zn(LPhH)2(MeCN), respectively. The X‐ray structures of Zn[LtBuLi(THF)]2, Zn2(LtBu)2(THF), Zn2(LPh)2(THF)2, and Zn(LtBuH)2(MeCN) are presented.
The N,N‐Bis(terphenyl)aminophosphenium Cation – A Sensitive Probe for Interactions with Different Anions
Authors: Reiß Fabian , Schulz Axel , Villinger Alexander
Published: December 2011

A series of salts that contain the terphenyl‐substitutedbis(amino)phosphenium cation with different anions (F–,Cl–, [CF3CO2]–, [CF3SO3]–, [B(C6F5)4]–, [GaCl4]–, [SbF6]–, [Al{OCH(CF3)2}4]– and [CHB11H5Br6]–) has been prepared by different synthetic protocols. All of the products have been characterised spectroscopically and by single‐crystal X‐ray diffraction studies. A detailed analysis of the interionic interactions and their influence on the molecular structure of the phosphenium cation reveals a strong dependence on the capability of the anion to enter the pocket generated by the bulky terphenyl substituents.
Stereo‐Inversion in the (4R)‐γ‐Decanolactone Synthesis by Saccharomyces cerevisiae: (2E,4S)‐4‐Hydroxydec‐2‐enoic Acid Acts as a Key Intermediate
Authors: Köhler Gunnar , Evans Paul , Garbe Leif‐Alexander
Published: December 2011

Methyl (2E,4R)‐4‐hydroxydec‐2‐enoate, methyl (2E,4S)‐4‐hydroxydec‐2‐enoate, and ethyl (±)‐(2E)‐4‐hydroxy[4‐2H]dec‐2‐enoate were chemically synthesized and incubated in the yeast Saccharomyces cerevisiae. Initial C‐chain elongation of these substrates to C12 and, to a lesser extent, C14 fatty acids was observed, followed by γ‐decanolactone formation. Metabolic conversion of methyl (2E,4R)‐4‐hydroxydec‐2‐enoate and methyl (2E,4S)‐4‐hydroxydec‐2‐enoate both led to (4R)‐γ‐decanolactone with >99% ee and 80% ee, respectively. Biotransformation of ethyl (±)‐(2E)‐4‐hydroxy(4‐2H)dec‐2‐enoate yielded (4R)‐γ‐[2H]decanolactone with 61% of the 2H label maintained and in 90% ee indicating a stereoinversion pathway. Electron‐impact mass spectrometry analysis (Fig. 4) of 4‐hydroxydecanoic acid indicated a partial C(4)→C(2) 2H shift. The formation of erythro‐3,4‐dihydroxydecanoic acid and erythro‐3‐hydroxy‐γ‐decanolactone from methyl (2E,4S)‐4‐hydroxydec‐2‐enoate supports a net inversion to (4R)‐γ‐decanolactone via 4‐oxodecanoic acid. As postulated in a previous work, (2E,4S)‐4‐hydroxydec‐2‐enoic acid was shown to be a key intermediate during (4R)‐γ‐decanolactone formation via degradation of (3S,4S)‐dihydroxy fatty acids and precursors by Saccharomyces cerevisiae.