bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Roundness Error Correction for the Ceramic Ball in Rotated Dual-Plates Lapping Process
Authors: Zhou Zhao Zhong , Yuan Ju Long , Lv Bing Hai , Zheng Jia Jin
Published: September 2009

The correction process of balls roundness error during lapping is discussed qualitatively. Dynamic analysis for rotated dual-plates lapping mode of ceramic balls is performed, under the assumption of a fluid loading system. The effect of the damping of the loading system on the correction of balls roundness error is discussed. And the result shows large damp causes an increase of magnification of load, and improves the correction of roundness error of balls.
Wear of Brazed Diamond Wheel in Grinding of Cemented Carbide
Authors: Zhan You Ji , Li Yuan , Huang Hui , Xu Xi Peng
Published: September 2009

Grinding forces, protrusion height, grinding temperatures and wear of diamond grits have been studied in grinding cemented carbide YG8 with a single-layer vacuum brazed diamond wheel. The experiment results indicate that the primary wear progression of diamond grits in the whole grinding process follows the mode of whole diamonds, flat diamonds when grinding of the cemented carbide. The worn mechanism of the failure of diamond grits was discussed and possible solutions are recommended. The proportions of diamond conditions and the mean protrusion height of grains are more closely related to grinding forces and grinding temperatures. The grinding forces, force ratio and grinding temperatures decreased with the increasing proportions of whole crystal and the decreasing mean protrusion height of diamond grits, and the tangential and normal force components increased with the gradual wear of the brazed diamond wheel during a long-time grinding process. It shows great potential in improving thermal damage of cemented carbides by reduces grinding temperature with vacuum brazing diamond wheels.
Simulation on the Indentation of Large Grain in the Semi-Fixed Abrasive Plate with Discrete Element Method
Authors: Yuan Ju Long , Tang Ke Feng , Wang Zhi Wei , Hong Tao
Published: September 2009

This paper analyses the influence of indenter’s vertex angle on the ‘trap’ effect of the semi-fixed abrasive plate (SAP) with discrete element method. The indenters of different degree vertex angle are generated by discrete element method, then the indenter is applied processing velocity, which let the indenter press into the SAP, finally three curves of normal force and displacement are gained. From the curves, the normal force of the indenters doesn’t increase quickly and stay in stable in the beginning, because the SAP is full of pore, which let the indenter easily press into the SAP. Through the above indenter simulation, the relations between the lasting time of the ‘trap’ effect and the indenter’s vertex angle are in reverse proportion, if the indenter’s vertex angle is smaller, the lasting time of the ‘trap’ effect of SAP is longer, and the size of large grain is an influence factor in the ‘trap’ effect of SAP.
Design of Simultaneous Ultrasonic Effects in Grinding and Electrofinishing on Taper Hole
Authors: Pa Pai Shan
Published: September 2009

The current study involves the use of ultrasonic vibration of the electrolyte to assist in removing electrolytic product and cuttings from the machining gap in the surface finish process of grinding and electro-finishing the inside surface of a tapered hole. The design of the finish-tool includes a taper grinding-tool joined to an electrode. In the experiment, the finish-tool is gradually fed into the taper hole and the electrode is used with continuous or pulsed direct current. The experimental results show that a high current together with ultrasonic vibration is effective in material removal and in the improvement of the finishing effect. The average effect of the ultrasonic vibration is greater than that of the pulsed current while the machining time need not be longer than the off-time. The finishing effect is better with a wide gap between the grinding-tool and the electrode. A high rotational speed of the finish-tool guides and discharges the dregs and cuttings efficiently and also improves the finish. The simultaneous use of ultrasonics with grinding and electro-finishing (SUGEF) also shortens the time it takes make the inside wall of the tapered hole smooth and bright.
Dressing Technology on the Diamond Abrasive Grinding Wheels Using the Rotary Diamond Dresser
Authors: Cui Zhong Ming , Deng Peng Hui , Du Lei
Published: September 2009

The dressing processes are conducted on the diamond grinding wheels using the rotary diamond tools and compared between the single point diamond dresser and the rotary diamond dressing tool in the following aspects, including the dressing force, tool wearing, dressing efficiency. The result shows that, the dressing performance of the rotary diamond tools is remarkable better than that of the conventional dressing method.
Research and Development of LM Neural Network Prediction System for Grind-Hardening
Authors: Pan Zhong Feng , Wang Gui Cheng , Hua Chong Lue , Pei Hong Jie
Published: September 2009

An improved neural network based on L-M algorithm has been applied to the prediction of the grind-hardening parameters against to the slow convergence rate of conventional BP neural network. And the the neural network model for grind-hardening is established. The neural network prediction system for grind-hardening process has been developed based on L-M algorithm. The functions of system is analyzed, particularly and some pivotal technology to realize the system are put forward.
Finite Element Prediction of Grind-Hardening Layer Thickness
Authors: Wang Gui Cheng , Pan Zhong Feng , Zhang Jin Yu , Hua Chong Lue , Liu Ju Dong
Published: September 2009

According to the grind-hardening test and using the multiple linear regression analysis, the empirical formula of the tangential grinding force is established in this paper. Combined with the heat distribution coefficient formula of Rowe and Pettit, the thickness of the grind-hardening layer is predicted by using the finite element method under different grinding parameters. It draws the influence law of the grinding speed, cutting depth and feed rate to the thickness of the grind-hardening layer. It provided the basis to the drawing up, the application and the optimization of the grind-hardening process.
Study on Compliant Control by Cutter Radius Compensating for Rotating Curved Surfaces Polishing on NC Lathes
Authors: Wu Ming Ming , Zhan Jian Ming , Zhang Jian Bo
Published: September 2009

. Lots of new automatic polishing methods and equipments have been developed to solve the problem of low efficiency and quality in the traditional handwork curved surfaces polishing. However, these methods and equipments are complex and difficult to be applied in the industrial production. This paper proposes a new technology of rotate surface compliant polishing based on NC lathe cutter radius compensation. An efficient and compact rotate surfaces compliant polishing system is developed, which consists of a NC lathe, flexible polishing tool, workpiece, fixture and also the automatic programming software MASTERCAM. The polishing tool-path and NC code can be created in MASTERCAM. The value of the cutter radius compensation can also be set in NC code, so that the rotated surfaces can be polished by a traditional NC lathe. Experiment of polishing the aluminum sphere workpiece is taken, and the satisfying surface quality is achieved.
Experimental and Mechanism Research on EDM Combined with Magnetic Field
Authors: Cao Ming Rang , Wang Yan Qing , Yang Sheng Qiang , Li Weng Hui
Published: September 2009

The two disadvantages of EDM are the low material removal rate (MRR) and poor surface quality. In this investigation, EDM assisted by magnetic field (MFEDM) has been proposed for the first time to overcome above-mentioned disadvantages. Constant magnetic field was applied to the both sides of discharge channel perpendicularly to form a novel process. In experiment, EDM machine tool D703F was used to machine nonferromagnetic materials. The machining parameters discharge current and pulse duration were chosen to determine the effects on material removal rate and surface roughness.Experiment results indicate that the MRR of the combined machining is 1.2~3 times of EDM’s one. Furthermore, the value of surface roughness is also reduced. Therefore, the introduction of magnetic field to EDM has important academic and practical values to the development of EDM.
The Development of Cutter Location Algorithm for the 6-Axis Simultaneous CNC Abrasive Belt Grinding Complex Surface
Authors: Huang Zhi , Huang Yun , Zhang Wei Wen , Wu Yue Yu
Published: September 2009

This paper brings forward a new method of calculating the cutter location data for 6-axis simultaneous CNC abrasive belt grinding complex surface based on the ACIS software kit, expatiates this belt grinding tool position calculation algorithm and key technique of software development, and verifies this algorithm with turbine blade on the 6-axis belt grinder, finally summarizes this new method also be applicable to other similar surface machining NC program system.
Clustering Regression Modeling for Gear Hobbing Machine Thermal Error Compensation
Authors: Guo Qian Jian , Qi Xiao Ni
Published: September 2009

This paper proposes a new thermal error modeling methodology called Clustering Regression Thermal Error Modeling which not only improves the accuracy and robustness but also saves the time and cost of gear hobbing machine thermal error model. The major heat sources causing poor machining accuracy of gear hobbing machine are investigated. Clustering analysis method is applied to reduce the number of temperature sensors. Least squares regression modeling approach is used to build thermal error model for thermal error on-line prediction of gear hobbing machine. Model performance evaluation through thermal error compensation experiments shows that the new methodology has the advantage of higher accuracy and robustness.
Comparison of Processing Features between Semi Bonded Abrasive Lapping and Loose Abrasive Lapping
Authors: Lv Xun , Yuan Ju Long , Wen Dong Hui
Published: September 2009

Semi bonded abrasive lapping is an effective ultra-precision lapping method. It can obtain good surface quality of workpiece in short time. This paper focused on the differences of processing features by comparing semi bonded abrasive lapping and loose abrasive lapping in several groups processing parameters. The results showed that the surface roughness of workpiece in semi bonded abrasive lapping was far superior to that of loose abrasive lapping in same processing parameters. And the MRR (material removal rate) of semi bonded abrasive lapping was slightly lower than that of loose abrasive lapping. For these features of semi bonded abrasive, a new processing flow would also be proposed in this paper.
Experimental Research on Deep Hole Honing of Difficult-to-Cut Materials Based on Mixture-Abrasive Honing Stones
Authors: Zhu Lin , Hai Peng , Xiao De Ming
Published: September 2009

The deep hole honing is an effective and precise method in deep hole processing. It can remove the machining allowance to ensure the hole size and the shape accuracy, and have better surface quality of a hole. The difficult-to-cut materials such as precipitation-hardening stainless steel, stainless steel (1Cr18Ni9Ti) and titanium alloy have the properties of high hardness, wear resistance, heat resistance, and corrosion resistance. The conventional single-abrasive honing stones can not handle the difficult-to-cut materials effectively because of their single-abrasive property. For higher efficiency, more than ten of mixture-abrasive honing stones with different proportion of different abrasives have been designed and the contrast experiments have been done for different mixture-abrasive honing stones to grind precipitation-hardening stainless steel, stainless steel (1Cr18Ni9Ti) and titanium alloy. According to several comprehensive evaluation factors of the grinding ratio, the specific grinding energy and the area that the honed chips stick the oilstones surface, the optimum proportion of different abrasives have been found for honing difficult-to-cut materials. It can be observed that the mixture-abrasive honing stones have better performance than that of single-abrasive stones when honing certain kind of difficult-to-cut materials.
Research on Grinding Model of Roller for Manufacturing Involute Spline
Authors: Zhang Feng Shou , Cui Feng Kui , Li Chun Mei , Wang Xiao Qiang
Published: September 2009

The paper studies the grinding process of cold roller. The shape of grinding wheel, the arc radius of grinding wheel, the motion trajectory of wheel center and the grinding force are analyzed. The mathematical model is established. The cold rolling experiment shows that the analyses and formula deduced in this paper are correct. It provides theoretical basis for designing and manufacturing roller and provides the mathematical guidance for making process parameter and designing grinding machine.
Experimental Study on the Dressing Force of Super-Abrasive Grinding Wheel with Elliptic Ultrasonic Vibration
Authors: Zhao Bo , Gao Guo Fu , Kong Qing Hua
Published: September 2009

A new dressing device for dense type diamond grinding wheel, whose elliptic vibration was prompted by single longitudinal vibration, was designed using a local resonance method. It was employed to dress the metallic bond super-abrasive grinding wheel and the dressing force characteristics were analyzed. The results indicate that the thrust force decreased to 1/7-1/10 of that of conventional method, and the main cutting force decreased by 70%. Compared to other dressing parameters, the dressing force in elliptic ultrasonic vibration was more sensitive to grinding speed. Thrust force and main cutting force increased rapidly when rotation speed beyond 72rpm. But when the ultrasonic power was higher than 50W, dressing force decreased very slowly. It was observed that the new dressing method is contribute to better surface finish such as more even surface, less crush abrasives, more uniform abrasive abscission and so on than the conventional method.
Comparisons of Surface Roughness for Precision Ground Different Brittle Materials
Authors: Shen Jian Yun , Xu Xi Peng
Published: September 2009

Brittle materials are popularly used as engineering materials for excellent properties. But the properties of brittle materials are different and special, and cause to different surface formation mechanism during the grinding process. In the study, surface roughnesses after grinding with different mesh size diamond wheels were measured. Combined with scanned surface topographies, the relation between the surface roughness and the properties of these brittle materials was discussed. It could be found that the material properties led to the different surface characteristics of brittle materials.
Detection and Recognition of Steel Ball Surface Defect Based on MATLAB
Authors: Lin Yong Zhi , Liu Xian Li , Han Hai Ying , Wang Yi Wen , Wang Peng
Published: September 2009

Taking MATLAB as the experimental platform, the detection and recongnition method of steel ball surface defect is put forward. With the method, we could determine whether there are surface defects or not, and identify the types of defects. The process of detection and recognition is as follows: Firstly, two-time wavelet de-noising treatment of the steel ball image is achieved by means of ecomposition, quantization of threshold and recongnition of Sym4 wavelet function, afterward, many collected noise of the steel ball image is reduced effectively. Secondly, the de-noised image is preprocessed and then we can calibrate the boundary of the defects accurately, which is used to extract the characteristic parameters of defects. Thirdly, the types of defects of steel ball are judged, and the process of pattern recognition is reasonablely designed by putting forward the shape parameter F, combined with the characteristic parameters of the defects. Lastly, the feasibility and validity of the detection and recongnition algorithm are verified by lots of analysis about experimental results especially the analysis on the experimental results comparing with the given data.
Error Separation and Correction Technology of Precision Measuring System in Aspheric Fine Grinding Phase
Authors: Wang Zhen Zhong , Guo Yin Biao , Guo Jiang , Xu Qiao
Published: September 2009

In precision measurement, the existed error of measuring system influences surface accuracy more. This paper provides an error analysis focusing on the research effort on aspheric lens on-machine measurement for form accuracy. And the error parameters including positioning error of coordinate origin, tilt angle and radius error of probe head are investigated. It was known that it was quite difficult to obtain the parameters by detecting instruments, so the method of error separation and correction based on measuring standard parts is presented in this paper to guide the inverse solution for higher measuring accuracy. Also, a measuring experiment with Φ210mm lens is executed. Experimental results indicate that the method based on standard parts is suitable for on-machine precision measuring of aspheric lens.
Research on Technology of Pulse Electrochemical and its Compound Finishing
Authors: Li Hong You , Guo Yin Biao , Liu Xiao Mei , Zhou Jin Jin
Published: September 2009

In this paper, Pulse electrochemical finishing (PECF) and pulse electrochemical compound finishing (PECCF) are introduced. The main technical parameters, including in intereletrode gap, current density, compositions of steel materials and pulse parameters on the resulting surface finish were studied. PECF and PECCF on different surface including plane and shafts surface are done. Well-pleasing experimental results is gained. Results indicate that PECF and PECCF can lead to both good smoothing efficiency and surface finish simultaneity at low costs.
A Method for Calculating the Maximal Temperature of Single Grain though Analyzing the Grinding Temperature Signal
Authors: You Fang Yi , Shen Jian Yun , Xu Xi Peng
Published: September 2009

In the present study, grinding temperature was measured by using a foil thermocouple when granite was ground by SiC wheel. De-noised the temperature signals with soft threshold method base on wavelet transform was conducted to analyze the grinding process. Energy partition to workpiece was estimated to be about 10%~30% by matching the measured temperature to analytically value. The number of active grains was determined by counting the high frequency impulses in the measured temperature signals. The ratio of active grains to total grains was about 4.5%~6.1%. Based on the results, a formula was deduced for calculating the temperature of single grain in the grinding process.
Functions of remembering and misremembering emotion
Authors: Levine Linda J. , Lench Heather C. , Safer Martin A.
Published: September 2009

Memory for the emotions evoked by past events guides people's ongoing behaviour and future plans. Evidence indicates that emotions are represented in at least two forms in memory with different properties. Explicit memories of emotion can be retrieved deliberately, in a flexible manner, across situations. Implicit memories of emotion are brought to mind automatically by cues resembling the context in which an emotional event occurred. One property they share, however, is that both types of memory are subject to forgetting and bias over time as people's goals and appraisals of past emotional events change. This article reviews the cognitive and motivational mechanisms that underlie stability and change in memory for emotion. We also address functions that remembering and misremembering emotion may serve for individuals and groups. Although memory bias is typically viewed as problematic, changes in representations of emotional experience often promote goal‐directed behaviour and facilitate coping with challenging situations. Copyright © 2009 John Wiley & Sons, Ltd.
Photoluminescence‐Based Sensing With Porous Silicon Films, Microparticles, and Nanoparticles
Authors: Sailor Michael J. , Wu Elizabeth C.
Published: September 2009

Here, chemical sensors made from porous Si are reviewed, with an emphasis on systems that harness photoluminescence and related energy‐ and charge‐transfer mechanisms available to porous Si‐derived nanocrystallites. Quenching of luminescence by molecular adsorbates involves the harvesting of energy from a delocalized nanostructure that can be much larger than the molecule being sensed, providing a means to amplify the sensory event. The interaction of chemical species on the surface of porous Si can exert a pronounced influence on this process, and examples of some of the key chemical reactions that modify either the surface or the bulk properties of porous Si are presented. Sensors based on micron‐scale and smaller porous Si particles are also discussed. Miniaturization to this size regime enables new applications, including imaging of cancerous tissues, indirect detection of reactive oxygen species (ROS), and controlled drug release. Examples of environmental and in vivo sensing systems enabled by porous Si are provided.
Palladium‐Catalyzed Oxidation of Phenyl‐Substituted Alkenes using Molecular Oxygen as the Sole Oxidant
Authors: Bueno Aline C. , de Souza Ágatha O. , Gusevskaya Elena V.
Published: September 2009

The palladium‐catalyzed aerobic oxidation of styrene and 2‐vinylnaphthalene in dimethylacetamide/water or dimethylformamide/water solutions under mild conditions has been developed, in which palladium(II) chloride is used in the absence of co‐catalysts or special stabilizing ligands as the sole and recyclable catalyst. The corresponding methyl ketones have been obtained in good to excellent yields with low catalyst loadings (0.2–5 mol%) and high turnover numbers (up to ca. 1000 to palladium). This simple and efficient catalytic method represents an ecologically benign and economically attractive synthetic pathway to industrially important compounds used in the manufacture of various polymers and drugs.
Bacillus subtilis Esterase (BS2) and its Double Mutant Have Different Selectivity in the Removal of Carboxyl Protecting Groups
Authors: Barbayianni Efrosini , Kokotos Christoforos G. , Bartsch Sebastian , Drakou Christina , Bornscheuer Uwe T. , Kokotos George
Published: September 2009

An esterase from Bacillus subtilis (BS2) and its double mutant E188W/M193C quickly hydrolyze n‐butyl, n‐propyl, methoxyethyl and allyl esters. The wild‐type BS2 preferentially removes such esters from the γ‐position of glutamate diesters, while the engineered enzyme has a reversed selectivity removing esters from the α‐position of glutamate diesters. Automated docking and molecular dynamic simulations were performed to understand the molecular reason for the different regioselectivity.
Recyclable Heterogeneous Supported Copper‐Catalyzed Coupling of Thiols with Aryl Halides: Base‐Controlled Differential Arylthiolation of Bromoiodobenzenes
Authors: Bhadra Sukalyan , Sreedhar Bojja , Ranu Brindaban C.
Published: September 2009

Alumina‐supported copper sulfate efficiently catalyzes the S‐arylation of aromatic, heteroaromatic and aliphatic thiols with aryl as well as heteroaryl halides under aerobic, ligand‐free conditions. This protocol provides an easy access to a variety of thioethers as well as unsymmetrical bis‐thioethers by base‐controlled differential coupling of thiols with iodo‐ and bromo‐substituents in an aromatic halide. The catalyst is inexpensive, non‐air sensitive, environmentally friendly and recyclable.
Chemical, Electrochemical, and Structural Properties of Endohedral Metallofullerenes
Authors: Chaur Manuel N. , Melin Frederic , Ortiz Angy L. , Echegoyen Luis
Published: September 2009

Ever since the first experimental evidence of the existence of endohedral metallofullerenes (EMFs) was obtained, the search for carbon cages with encapsulated metals and small molecules has become a very active field of research. EMFs exhibit unique electronic and structural features, with potential applications in many fields. Furthermore, functionalized EMFs offer additional potential applications because of their higher solubility and their ease of characterization by X‐ray crystallography and other techniques. Herein we review the general field of EMFs, particularly of functionalized EMFs. We also address their structures and their (electrochemical) properties, as well as applications of these fascinating compounds.
Close mimicry of lung surfactant protein B by “clicked” dimers of helical, cationic peptoids
Authors: Dohm Michelle T. , Seurynck‐Servoss Shannon L. , Seo Jiwon , Zuckermann Ronald N. , Barron Annelise E.
Published: September 2009

A family of peptoid dimers developed to mimic SP‐B is presented, where two amphipathic, cationic helices are linked by an achiral octameric chain. SP‐B is a vital therapeutic protein in lung surfactant replacement therapy, but its large‐scale isolation or chemical synthesis is impractical. Enhanced biomimicry of SP‐B's disulfide‐bonded structure has been previously attempted via disulfide‐mediated dimerization of SP‐B1‐25 and other peptide mimics, which improved surface activity relative to the monomers. Herein, the effects of disulfide‐ or “click”‐mediated (1,3‐dipolar cycloaddition) dimerization, as well as linker chemistry, on the lipid‐associated surfactant activity of a peptoid monomer are described. Results revealed that the ‘clicked’ peptoid dimer enhanced in vitro surface activity in a DPPC:POPG:PA lipid film relative to its disulfide‐bonded and monomeric counterparts in both surface balance and pulsating bubble surfactometry studies. On the pulsating bubble surfactometer, the film containing the “clicked” peptoid dimer outperformed all presented peptoid monomers and dimers, and two SP‐B derived peptides, attaining an adsorbed surface tension of 22 mN m−1, and maximum and minimum cycling values of 42 mN m−1 and near‐zero, respectively. © 2009 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 92: 538–553, 2009.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Copper‐Catalyzed Amine–Alkyne–Alkyne Addition Reaction: An Efficient Method For the Synthesis of γ,δ‐Alkynyl‐β‐amino Acid Derivatives
Authors: Zhou Lei , Shuai Qi , Jiang Huan‐feng , Li Chao‐Jun
Published: September 2009

A simple and efficient method for the synthesis of γ,δ‐alkynyl‐β‐amino acid derivatives by a copper‐catalyzed three‐component amine–alkyne–alkyne addition reaction was developed. Various γ,δ‐alkynyl‐β‐amino acid derivatives were synthesized in moderate to good yields in one step. With chiral prolinol derivatives employed as the amine component, excellent diastereoselectivities (up to >99:1 diastereomeric ratio (dr)) were obtained. The scope of the reaction and further transformations of the resulting amino acid derivatives, such as deprotection and cyclization are also described.
Macroscopic assessment of mesorectal excision
Authors: Enker Warren E. , Levi Gabriel S.
Published: September 2009

Total mesorectal excision (TME) has become the surgical standard of care for rectal cancer. Macroscopic assessment of mesorectal excision (MAME) using digital photography, affords a visual image for grading the completeness of TME (MA‐0 to MA‐2). Such a grading system can enhance the evaluation of the surgical baseline or platform used in randomized clinical trials, play a role in determining the need for adjuvant therapy in borderline situations (ie, T3N0M0 disease) or determine the care of patients who despite TME, might develop local recurrences.
From commodity computers to high‐performance environments: scalability analysis using self‐similarity, large deviations and heavy‐tails
Authors: Ramirez‐Velarde Raul V. , Rodríguez‐Dagnino Ramón M.
Published: September 2009

We derive two scalability models for high‐performance distributed environments using low‐cost, low‐performance components. On the first model, we approximate the tail of the probability distribution by using the Pareto probability distribution and then build a stochastic model to determine the maximum user‐load per server according to certain quality of service parameters. On the second model, we use a probabilistic measure to determine the ratio of computing servers to storage servers and thus complete the performance model. The data of execution traces obtained from the testbed is analyzed. Hurst parameter is estimated using the Abry–Veitch estimator and distribution parameters are estimated for different probability distributions. Models based on the Pareto and Gamma probability distributions are developed and used with the data that was analyzed. There seems to be a good agreement between our models, the experimental execution traces, and simulations of HP computing environments. Specifically, thePareto Fractal Flowmodel is compared with other models based on the Gamma and Gaussian distributions, such as the FGN andM/G/∞, and it seems to make better predictions under our experimental conditions. Results are presented comparing analytical models with simulation results. Copyright © 2009 John Wiley & Sons, Ltd.
Effect of Bi‐content on hardness and micro‐creep behavior of Sn‐3.5Ag rapidly solidified alloy
Authors: Kamal M. , Gouda El Said , Marei L. K.
Published: September 2009

In the present paper, the influence of 1, 3, 5 and 10 % Bi (weight %) as ternary additions on structure, melting and mechanical properties of rapidly solidified Sn‐3.5Ag alloy has been investigated. The effect of Bi was discussed based on the experimental results. The experimental results showed that the alloys of Sn‐3.5Ag, Sn‐3.5Ag‐1Bi and Sn‐3.5Ag‐3Bi are composed of two phases; Ag3Sn IMC embedded in Sn matrix phase, which indicated that the solubility of Bi phase in Sn‐matrix was extended to 3 % as a result of rapid solidification. Bi precipitation in Sn matrix was only observed in Sn‐3.5Ag‐5Bi and Sn‐3.5Ag‐10Bi alloys. Also, addition of Bi decreased continuously the melting point of the eutectic Sn‐3.5Ag alloy to 202.6 °C at 10 % Bi. Vickers hardness of Sn‐3.5Ag rapidly solidified alloy increased with increasing Bi content up to 3 % due to supersaturated solid solution strengthening hardening mechanism of Bi phase in Sn matrix, while the alloys contain 5 and 10 % Bi exhibited lower values of Vickers hardness. The lower values can be attributed to the precipitation of Bi as a secondary phase which may form strained regions due to the embrittlement of Bi atom. In addition, the effect of Bi addition on the micro‐creep behavior of Sn‐3.5Ag alloy as well as the creep rate have been described and has been calculated at room temperature. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rapid flow cytometric method for measuring senescence associated β‐galactosidase activity in human fibroblasts
Authors: Noppe Gerard , Dekker Pim , de Koning‐Treurniet Corine , Blom Joke , van Heemst Diana , Dirks Roeland W. , Tanke Hans J. , Westendorp Rudi G. J. , Maier Andrea B.
Published: September 2009

Senescence associated‐β‐galactosidase (SA‐β‐gal) activity is a widely used marker for cellular senenescence. SA‐β‐gal activity is routinely detected cytochemically, manually discriminating negative from positive cells. This method is time‐consuming, subjective and therefore prone to operator‐error. We aimed to optimize a flow cytometric method described by other workers using endothelial cells to better differentiate between populations of fibroblasts in degrees of SA‐β‐gal activity. Skin fibroblasts were isolated from young (mean age ± SD: 25.5 ± 1.8) and very old (age 90.2 ± 0.3) subjects. Different pH modulators were tested for toxicity. To induce stress‐induced senescence, fibroblasts were exposed to rotenone. Senescence was assessed measuring SA‐β‐gal activity by cytochemistry (X‐gal) and by flow cytometry (C12FDG). The pH modulator Bafilomycin A1 (Baf A1) was found to be least toxic for fibroblasts and to differentiate best between nonstressed and stressed fibroblast populations. Under nonstressed conditions, fibroblasts from very old subjects showed higher SA‐β‐gal activity than fibroblasts from young subjects. This difference was found for both the flow cytometric and cytochemical methods (P = 0.013 and P = 0.056 respectively). Under stress‐induced conditions the flow cytometric method but not the cytochemical method revealed significant higher SA‐β‐gal activity in fibroblasts from very old compared to young subjects (P = 0.004 and P = 0.635 respectively). We found the modified flow cytometric method measuring SA‐β‐gal activity superior in discriminating between degrees of senescence in different populations of fibroblasts. © 2009 International Society for Advancement of Cytometry
Regioselective Domino Metathesis of Unsymmetrical 7‐Oxanorbornenes with Electron‐Rich Vinyl Acetate toward Biologically Active Glutamate Analogues
Authors: Oikawa Masato , Ikoma Minoru , Sasaki Makoto , Gill Martin B. , Swanson Geoffrey T. , Shimamoto Keiko , Sakai Ryuichi
Published: September 2009

In this article a regioselective domino metathesis reaction of unsymmetrical 7‐oxanorbornenes, readily available by a tandem Ugi/Diels–Alder reaction as a key step, promoted by the Hoveyda–Grubbs second‐generation catalyst in the presence of electron‐rich vinyl acetate as a cross metathesis (CM) substrate is reported. The mechanism for the unusually high regioselectivity observed in the CM reaction was investigated, and a reaction course where a Fischer‐type carbene [“Ru”=CH(OAc)] generates a steric interaction is proposed. Themetathesis products were further converted to four artificial glutamate analogues whose structures were inspired by naturally derived excitatory glutamate analogues, dysiherbaine and neodysiherbaine. Interestingly, one of the synthetic analogues (28a) induced a cataleptic state in mice. Further electrophysiological studies suggest that28amight inhibit excitatory synaptic transmission by a yet unknown indirect pathway.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Label‐Free and Ultra‐Low Level Detection of Salmonella enterica Serovar Typhimurium Using Electrochemical Impedance Spectroscopy
Authors: La Belle Jeffrey T. , Shah Miti , Reed Justin , Nandakumar Vivek , Alford T. L. , Wilson James W. , Nickerson Cheryl A. , Joshi Lokesh
Published: September 2009

An immunosensor for rapid and low level detection of the bacterial pathogen Salmonella enterica Serovar Typhimurium was designed and developed based upon label‐free electrochemical impedance spectroscopy and correlated to viable cell counts. The immunosensor was fabricated by electroplating gold onto a disposable printed circuit board (PCB) electrode by immobilizing monoclonal antibody (MAb) specific against Salmonella typhimurium cell surface lipopolysaccharide (LPS) onto the surface of the electrode. Use of mass‐fabricated and electroplated PCB electrodes allowed for disposable, highly sensitive, and rapid detection of Salmonella in an aqueous environment. Results demonstrate that in purified solution, Salmonella can be detected as low as 10 CFU in a 100 μL volume and label‐free and rapid manner in fewer than 90 s. The cost effective approach described here can be used for detection of pathogens with relevance for healthcare, food, and environmental applications.
The neural response to changing semantic and perceptual complexity during language processing
Authors: Sharp David J. , Awad Malaka , Warren Jane E. , Wise Richard J.S. , Vigliocco Gabriella , Scott Sophie K.
Published: September 2009

Speech comprehension involves processing at different levels of analysis, such as acoustic, phonetic, and lexical. We investigated neural responses to manipulating the difficulty of processing at two of these levels. Twelve subjects underwent positron emission tomographic scanning while making decisions based upon the semantic relatedness between heard nouns. We manipulated perceptual difficulty by presenting either clear or acoustically degraded speech, and semantic difficulty by varying the degree of semantic relatedness between words. Increasing perceptual difficulty was associated with greater activation of the left superior temporal gyrus, an auditory‐perceptual region involved in speech processing. Increasing semantic difficulty was associated with reduced activity in both superior temporal gyri and increased activity within the left angular gyrus, a heteromodal region involved in accessing word meaning. Comparing across all the conditions, we also observed increased activation within the left inferior prefrontal cortex as the complexity of language processing increased. These results demonstrate a flexible system for language processing, where activity within distinct parts of the network is modulated as processing demands change. Hum Brain Mapp, 2010. © 2009 Wiley‐Liss, Inc.
Evaluation of the immunogenicity and cell compatibility of avian collagen for biomedical applications
Authors: Peng Yong Y. , Glattauer Veronica , Ramshaw John A. M. , Werkmeister Jerome A.
Published: September 2009

There have been concerns regarding the suitability of bovine collagen as a biomaterial since the emergence of bovine spongiform encephalopathy. Consequently, collagens from other species may be used if they can meet appropriate standards, including negligible or lack of immunogenicity. In this study, the potential immunogenicity of both monomeric and pepsin‐solubilized chicken collagens have been compared with a commercial, pepsin‐solubilized bovine collagen that is approved for biomedical implantation. All collagens were poor immunogens compared with ovalbumin. No IgE responses were detected in sera of three strains of mice, and no hypersensitivity reactions were found in guinea pigs in maximization and Buehler tests. IgG1 antibodies were found although the titre was substantially lower than against ovalbumin. All responses in mice and rabbits were found only when immunizations were performed with adjuvant, and after multiple injections over a long period of time. The response from the monomeric chicken collagen was less than for pepsin‐solubilized collagens. Collagen sponges prepared from the two chicken collagen preparations both supported the attachment and growth of mouse fibroblasts. These data indicate that chicken collagen, particularly when monomeric, may be useful in certain biomedical applications. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
The notch‐responsive transcription factor Hes‐1 attenuates osteocalcin promoter activity in osteoblastic cells
Authors: Zhang Ying , Lian Jane B. , Stein Janet L. , van Wijnen Andre J. , Stein Gary S.
Published: September 2009

Notch signaling plays a key role in osteoblast differentiation. A major transcriptional downstream regulator of this pathway is the helix–loop–helix (HLH) transcription factor Hairy/Enhancer of Split 1 (Hes‐1). Here we investigated the function of Hes‐1 in osteoblastic cells. Endogenous Hes‐1 gene expression decreases during progression of bone cell phenotype development in MC3T3‐E1 osteoblasts suggesting that it is a negative regulator of osteoblast differentiation. Forced expression of Hes‐1 inhibits osteocalcin (OC) mRNA levels, and luciferase assays indicate that Hes‐1 directly represses OC promoter activity. In vitro and in vivo protein/DNA interaction assays reveal that recombinant Hes‐1 binds specifically to an E‐box in the proximal promoter of the OC gene. Deletion of the Hes‐1 WRPW domain (MHes‐1) that recruits the co‐repressor Groucho abrogates repression of OC promoter activity by Hes‐1, but also blocks Hes‐1 binding to the promoter. The latter result suggests that exogenous Hes‐1 may be recruited to the OC promoter by both protein/DNA and protein/protein interactions. We conclude that the Notch‐responsive Hes‐1 protein is capable of repressing OC gene transcription in osteoblastic cells through an E‐box in the proximal promoter. Hes‐1 may contribute to osteoblast growth and differentiation by controlling basal bone‐specific transcription directly through interactions with transcriptional regulators that are known to bind to the OC gene promoter. J. Cell. Biochem. 108: 651–659, 2009. © 2009 Wiley‐Liss, Inc.
An information‐theoretic approach to the prediction of protein structural class
Authors: Zheng Xiaoqi , Li Chun , Wang Jun
Published: September 2009

An information‐theoretical approach, which combines a sequence decomposition technique and a fuzzy clustering algorithm, is proposed for prediction of protein structural class. This approach could bypass the process of selecting and comparing sequence features as done previously. First, distances between each pair of protein sequences are estimated using a conditional decomposition technique in information theory. Then, the fuzzy k‐nearest neighbor algorithm is used to identify the structural class of a protein given as set of sample sequences. To verify the strength of our method, we choose three widely used datasets constructed by Chou and Zhou. It is shown by the Jackknife test that our approach represents an improvement in the prediction of accuracy over existing methods. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010
Mathematical modelling of the impact of haematopoietic stem cell‐delivered gene therapy for HIV
Authors: Murray John M. , Fanning Greg C. , Macpherson Janet L. , Evans Louise A. , Pond Susan M. , Symonds Geoff P.
Published: September 2009

Background

Gene therapy represents a new treatment paradigm for HIV that is potentially delivered by a safe, once‐only therapeutic intervention.

Methods

Using mathematical modelling, we assessed the possible impact of autologous haematopoietic stem cell (HSC) delivered, anti‐HIV gene therapy. The therapy comprises a ribozyme construct (OZ1) directed to a conserved region of HIV‐1 delivered by transduced HSC (OZ1+HSC). OZ1+HSC contributes to the CD4+ T lymphocyte and monocyte/macrophage cell pools that preferentially expand under the selective pressure of HIV infection. The model was used to predict the efficacy of OZ1 in a highly active antiretroviral therapy (HAART) naïve individual and a HAART‐experienced individual undergoing two structured treatment operations. In the standard scenario, OZ1+HSC was taken as 20% of total body HSC.

Results

For a HAART‐naïve individual, modelling predicts a reduction of HIV RNA at 1 and 2 years post‐OZ1 therapy of 0.5 log10 and 1 log10, respectively. Eight years after OZ1 therapy, the CD4+ T‐lymphocyte count was 271 cells/mm3 compared to 96 cells/mm3 for an untreated individual. In a HAART‐experienced individual HIV RNA was reduced by 0.34 log10 and 0.86 log10 at 1 and 2 years. The OZ1 effect was maximal when both CD4+ T lymphocytes and monocytes/macrophages were protected from successful, productive infection by OZ1.

Conclusions

The modelling indicates a single infusion of HSC cell‐delivered gene therapy can impact on HIV viral load and CD4 T‐lymphocyte count. Given that gene therapy avoids the complications associated with HAART, there is significant potential for this approach in the treatment of HIV. Copyright © 2009 John Wiley & Sons, Ltd.
The impact of adsorption of bovine pancreatic trypsin inhibitor on CTAB‐protected gold nanoparticle arrays: a Raman spectroscopic comparison with solution denaturation
Authors: Kaminska Agnieszka , Forster Robert J. , Keyes Tia E.
Published: September 2009

The influence of an array of cetyltrimethylammonium bromide (CTAB)‐protected gold nanoparticles on the structure of a model protein, bovine pancreatic trypsin inhibitor (BPTI) at pH 7.4, was studied by Raman spectroscopy. The structural consequences of array adsorption were compared with the effects of deposition of the protein directly onto a roughened gold substrate and with thermal and reductive treatment of BPTI in solution. Both thermal and reductive denaturation in solution result in loss of α‐helix structure, with an increase in random conformations of the protein in the case of reductive denaturation and β‐sheet conformation and random coil on thermal denaturation. For reductive denaturation in particular, extensive loss of secondary structure is evident. Deposition of the protein onto the array resulted in increased β‐sheet conformation similar to that observed on thermal treatment of the protein. However, unlike denaturation, which for both thermal and reductive process resulted in changes in the disulfide stretching wavenumber, this remains largely unchanged on application of the protein to the array. Furthermore, deposition of the protein onto bare gold results in significant heterogeneity in the SS stretching signal with appearance of ggt and nonequilibrium geometry of the CCSSCC dihedral angles. Thermal denaturation results in a red shift of the SS mode, whereas dithiothreitol (DTT) treatment, as expected, induces significant loss of the SS stretching signal, although a signal at 517 cm−1 remains suggesting that the unreduced disulfide has changed to the ggt geometry. In addition, an SH mode is observed at 2570 cm−1 in solution. The response of BPTI to thermal and DTT treatment while on the array is very different to its solution behavior, and suggests that adhesion to the array increases the stability of the protein. Copyright © 2009 John Wiley & Sons, Ltd.
Influence of oil type on the performance characteristics of a two‐axial groove journal bearing
Authors: McCarthy D. M. C. , Glavatskih S. B. , Byheden Å.
Published: September 2009

The use of environmentally adapted lubricants (EALs) is a subject of growing interest to industry as legislation increasingly demands the replacement of mineral oil lubricants. Vegetable‐based fluids are widely seen as providing lubricants from a renewable source, as well as meeting demands for improved biodegradability. However, at present, utilization of such fluids is limited due to their rapid oxidation. EALs produced from other base stocks (i.e. synthetic esters) have been shown to provide performance benefits in hydrodynamic thrust bearings. In the present study, a hydrodynamic journal bearing test rig has been employed to compare the performance of three EALs (a VG32 saturated ester, rapeseed base fluid and a propylene glycol dioleate) relative to three mineral turbine oils (ISOVG32, ISOVG46 and ISOVG68) in the hydrodynamic regime. Results are given in terms of temperature, power loss and minimum film thickness. The impact of oil viscosity index is also discussed. Copyright © 2009 John Wiley & Sons, Ltd.
A planar CPW‐fed slot antenna on thin substrate for dual‐band operation of WLAN applications
Authors: Yoon Cheol , Lee Won‐Jong , Kang Sang‐Pil , Kang Suk‐Youb , Lee Hwa‐Choon , Park Hyo‐Dal
Published: September 2009

This article presents the design and fabrication of a coplanar waveguide (CPW)‐fed slot antenna on thin substrate for dual‐band operation of wireless local‐area network (WLAN) applications within 2.400–2.484 GHz and 5.150–5.350/5.725–5.825 GHz bandwidths. The prototype consists of a thin substrate and a CPW‐fed slot antenna. To obtain sufficient bandwidth with −10 dB return loss, a thin substrate layer is inserted under the ground plate and the radiator. A thin substrate CPW‐fed slot antenna that has a WLAN‐band is used. The important design parameters are the slot's construction, width, length, the substrate height, and the CPW‐fed gaps. From these optimized parameters, a CPW‐fed slot antenna is fabricated and measured. The measured results of the fabricated antenna are obtained individually, at 1.70 and 2.40 GHz bandwidths, with a −10 dB return loss referenced to the center frequency, and with the individual peak gains at 1.37 and 1.78 dBi. The experimental radiation efficiency in both the E‐ and H‐planes is shown to be a pass band total of 48–75%. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2799–2802, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24742