bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of Velocity Loop Parameters in CNC Servo System
Authors: Yu Bin Gao , Shi Lin , Wang Kun Qi
Published: December 2011

To optimizing efficiently control parameters in feed servo system for adequately giving out the CNC machine tools, the velocity loop control model is built, and the comprehensive evaluation function is given. The standard particle swarm algorithm is improved to optimizing the parameters of velocity loop control in CNC machine tools. It shows the best overall performance of the velocity loop in CNC machine tools that parameters optimized by improved particle swarm algorithm Compared with genetic algorithm, the standard particle swarm algorithm and handy calculation. This optimized algorithm is a new efficient ways to solve parameter optimization of CNC servo control system.
Mathematical Model of Thermal Deformation in Precision Measurement and its Application
Authors: Ma Xiao Li , Qiang Huai Bo , Feng Xiao Zhou
Published: December 2011

As everyone knows, the temperature changes can cause the changes of mechanical geometric size. The thermal deformation obtained by traditional calculation formulas are approximate and linear, used in low precision requirement, however, if applied in high precision field, it is very limited. In this paper, by using the relations between crystal material line expansion coefficient and volume expansion coefficient, we will establish the thermal deformation mathematical model of cylindrical shaft and hole parts in the steady temperature, the model will consider the effects of the shape factors of parts on thermal deformation.
Design of Intelligent Spray Equipment
Authors: Chu Miao , Tian Shao Hui , Yu Sui Huai
Published: December 2011

This paper has a deeply research on spray equipment based on actual project by applying method of intelligent control modules. This paper realized intellectualized management of spray color, using the research achievement to actual project, which validated the feasibility of the research.
Experimental Study on 3-Phase Abrasive Waterjet Deburring
Authors: Wang Qing Hua , Deng Dong Hua , Huang Bo
Published: December 2011

Burrs are unnecessary by-products produced by cutting metal in a machining process. It greatly affects product quality and assembly efficiency, and also affects product cost. Therefore, burrs must be removed and the surface quality must be maintained. Contrary to abrasive waterjet, 3-phase abrasive waterjet has same machining effect on a workpiece without an additional equipment to meet its circulatory requirement. An experiment was performed to analyze the effect of the 3-phase abrasive waterjet parameters on burr removal and surface quality.
The Investigation on the Abrasive Jet to Change the Contact Angle of Solid Material Surface
Authors: Zhang Qiao Ling , Li Fu Yuan , Li Xiao Xia , Liu Pu
Published: December 2011

In order to change surface morphology and contact angle of part, abrasive jet method is discussed in the paper. Glass, steel and titanium are used to study its surface morphology by the processing of abrasive to jet the surface. In addition, the extent of its impact of processing method is studied with different abrasive size. Experiment method and environment are also introduced, and experiment shows that contact angle of glass changes from 14.9° to 93.8° (Titanium and steel also have different degrees of diversification). According to experiment of the method, abrasive jet methods affects contact angle, and it has the value of further research.
Forming Shape of Narrow Groove Machined by Electro Jet Machining
Authors: Li Xiao Xia , Li Fu Yuan , Zhang Qiao Lin
Published: December 2011

In order to study small size three dimensional shape processing of electro jet machining, the micro-channel principle is introduced firstly. Moreover, narrow groove processing experiment design and construction process is described, and experimental purpose is to change the cycle times to research the rule of groove width and depth. The experimental results indicate that when the width of the groove reaches a certain value, it will be stabilized and fluctuate around the value. However, with the increasing of the cycle number, groove depth increases. If cycle times are less than 7, the overall shape of the groove is a part of an approximate ellipse, otherwise it is changed but the bottom shape of the groove is still a part of an approximate ellipse.
Outspread Sheet Metal Algorithm of Oblique Square Dome Pipe Considering Thickness
Authors: Bai Yu , Min Hui , Chen Hua , Cao Yan
Published: December 2011

In order to resolve inaccuracy and low efficiency problem for sheet metal outspread, a new sheet metal outspread method is proposed for oblique square dome shaped pipe. Three dimensional model oblique square dome pipe sheets is firstly constructed and unfolding function is realized in VC++ 6.0. In addition, thickness disposal and unfolding mathematic model are also discussed. Lastly, oblique square dome shaped pipe unfolding method is introduced in detail by taking for an instance, and it shows that the auto unfolding method was effective on sheet metal of oblique square dome shaped pipe unfolding.
Research on Dynamic Coupling Characteristics of Electrostatic Actuated Micro Beam Considering Gas Film Damping
Authors: Wang Wei Dong , Ji Xiang , Niu Xiang Yu
Published: December 2011

It has been proved by large number of experiments that gas film damping has great influence on MEMS structures. Based on the elastic and material mechanics, this paper built a linear-vibration model for the electrostatic actuated micro-beam. According to the rarefied gas dynamics theory, a kind of modified Reynolds equation is adopted in the system modeling. In view of the study on small deflection of micro-beam has been investigated already by many researchers, this paper focus the research on large beam deflections, i.e. the mid-point deflection can be compared with the thickness of the gas film. The dynamic characteristics of micro-beam are investigated through coupling the dynamic vibration equation with the modified Reynolds equation. Through the finite difference method, the discrete form of the coupled dynamic equations has been obtained.
An Experimental Research of Gaseous Flow in Rough Microchannels
Authors: Ren Taian , Chang Lan , Zhao Jing Yun , Qin Ge
Published: December 2011

With the development of MEMS technology and its increasing applications in many engineering fields, the experimental research on micro-scale fluidic theory has become a spotlight topic in the past decade. In this paper, numerical and experimental investigations on the effects of roughness, compressibility and gas rarefaction on the nitrogen flow in rough microchannels had been investigated. Microchannels based on silicon substrates were fabricated by the MEMS process. Roughness surfaces of the microchannels had been obtained by KOH and TMAH solutions with different solubility etching on (100) silicon wafer. The quality of the microchannels was performed with a SEM and the measurements and the overall size of the microchannels were carried out with a step profiler. The Pyrex® 7740 and silicon wafers were packaged using the anodic bonding method. The testing platform was designed and fabricated, and checked for the gas sealing. Finally, the experimental device was constructed, and the results of gas flow in rough microchannels were measured.
Parametric Design of Parallel Indexing CAM Based on VB
Authors: Xia Tian , Liu Peng , Jiang Xiao Yang , Huang Ying
Published: December 2011

Through the establishment of mathematical model of parallel indexing cam, a calculation method of the cam contour line is discovered. Then achieve automatic calculation about point in cam profile based on VB programming. Eventually output plots by SolidWorks.
Analysis and Application of Phase Change Materials on Energy Saving in Buildings
Authors: Wang An , Hu Ming Wen , Tao Deng Ke , Wang Jing
Published: December 2011

Current research on building energy efficiency and the application of the principle of the phase change materials are outlined. Analysis of research regarding phase change materials and their classifications on energy-saving in buildings are analyzed and the main existing issues are summarized. The energy-saving effect is verified with the utilization of paraffin and swelling soil composite phase change materials, the result of which suggests that room temperature can be comparatively stabilized with the utilization of phase change materials and energy efficiency can be critically increased. This demonstrates that phase change materials have a broad potential in engineering endeavors.
Evolutions of Microstructure for Multilayered Al-Mg Alloy Composites by Accumulation Roll Bonding (ARB) Process
Authors: Zhang Bing , Chen Zhong Wei , Yuan Shou Qian , Zhao Tian Li
Published: December 2011

In this paper, accumulative roll bonding (ARB) has been used to prepare the Al/Mg alloy multilayer structure composite materials with 1060Al sheet and MB2 sheet. The evolution of microstructure of the cladding materials during ARB processes was observed by optical microscope, scanning electron microscopy, and micro-hardness was measured by micro-hardness tester. The results show that a multilayer structure material of Al/Mg alloy with excellent bonding characteristics and fine grained microstructure was prepared by ARB processes. With the ARB cycles increasing, Mg alloy layer in multilayer composite material was necked and fractured, and the hardness of the Al and Mg alloy was increased. Average grain size was less than 1μm after ARB4 cycles.
A Study on the Laser Induced Damage of Diamond-Like Carbon Film
Authors: Wu Shen Jiang , Su Jun Hong
Published: December 2011

This paper describes the structure and performances of Diamond-Like Carbon (DLC) films and introduces the film damage testing principle and methods. It also compares the different deposition techniques of DLC film laser induced damage threshold (LIDT), highlighting the influence of external electric field on the DLC film's LIDT. The photoelectron produced by the excitation of laser and the free electron in DLC film will perform a speedy movement, it indirectly decreases some part of the laser-irradiated area energy density, slows down the DLC film's graphitizing process and consequently improves its anti-laser damage ability.
Wearability of Non-Smooth Surface with Laser Treatment in the Different Cooling Media
Authors: Yu Zhen Wen , Xiu Wen Cui , Chen Li
Published: December 2011

This paper compared wearability of the non-smoothed unit body of the samples treated in water medium with in air, by studying on cast iron intimating the body surface organism at the same laser processing parameters. The research indicated that the size and microhardness of non-smoothed unit body determined the wearability of the samples, and the wearability of the samples treated in water medium was relatively better than in the air.
Inhibition of Mild Steel by Conducting Coal Based Polyaniline
Authors: Lin Wei Li , Deng Yu Qiang , Wu Sheng Jiang
Published: December 2011

The effect of coal based polyaniline compounds (CPANI) added into epoxy coating on the corrosion of mild steel in solutions of 5% sodium chloride (NaCl) has been investigated in relation to the proportion of the CPANI from 0% to 40% by various monitoring corrosion techniques. Interface morphology was studied by SEM. Results obtained revealed that the CPANI compound has good inhibitive corrosion for mild steel.
Structure Design of 2D Convert Probe by Single-Sensor
Authors: Guo Jing Bin , Zhang Ji Cheng
Published: December 2011

A 2-D convert micrometer probe by single-sensor for gear measurement. One group of parallel leaf springs was used as the micro-movement guide rail. A precise transducer was used as the detector and a special slope is used as conversion device. The gear’s tangential measurement and radial measurement can be achieved by only one sensor. In this paper, the overall structure of the probe was studied. Using geometry method, probe’s radial displacement caused by tangential measurement in the structure of parallel leaf springs was analyzed and the probe’s two-dimensional convert structure was discussed.
An Artificial Immune Inspired Hybrid Classification Algorithm and its Application to Fault Diagnosis
Authors: Li Gang , Yang Ming , Zhuang Jian
Published: December 2011

To efficiently mining the classification model, an artificial immune inspired hybrid classification algorithm was put forward by means of combining antibody clonal selection, fuzzy C means clustering (FCM) and information entropy principle. In this algorithm, fuzzy C means clustering algorithm was employed to generate initial antibody population for making use of the prior knowledge of the training data. From the viewpoint of information entropy, for evolving memory cells the information entropy of antibodies population was employed to provide stop criteria of training. Finally classification was performed in a nearest neighbor approach. Experimental results on the fault detection of DAMADICS demonstrate the effectiveness of the algorithm. Compared with CLONALG artificial immune classifiers, the hybrid classifier has a superior performance in terms of recognition rate, computation time, number of memory cells and condense rate.
A Small Magnetic Driving ECM Machine
Authors: Zhang Chang Fu , Wang Fa Guang , Xu Shi Yu
Published: December 2011

To solve the problems (long transmission chain, poor reachability, complicated structure, etc.) of current electrochemical machining (ECM) machines, a small magnetic driving ECM machine was designed. The working principle of the machine is introduced, magnetic driving system and electrolyte system of the machine are designed in this paper, and strength and deformation analysis of bed is performed by ANSYS software. Drive system and transmission system working as a whole part could directly drive cathode to machine workpieces without long transmission chain. The small magnetic driving ECM machine could machine holes, curved surface, internal grooves and other complicated-shape parts with high accuracy.
Pentecostalism and schisms in the Reformed Church in Zambia (1996–2001): Listening to the people
Authors: Soko Lukas , Hendriks H. Jurgens
Published: December 2011

This article is descriptive in nature and a practical theological assessment of the schisms that took place in the Reformed Church in Zambia (RCZ) between 1996 and 2001. It analyses empirical evidence to find an answer to the question why it happened. Pentecostal or charismatic tendencies have challenged the long inherited tradition of mainline churches. Subsequently, Pentecostal or charismatic movements have caused intense conflict in the church between the pro-conservatives and pro-Pentecostals. In the RCZ this led to the formation of the Christian Reformed Church (CRC) in 1999 and the Bible Gospel Church in Africa (BIGOCA) in 2001.
Histories-vergelykende ekklesiologie – Oppad na ’n omvattende Praktiese Ekklesiologie
Authors: Dreyer Wim A.
Published: December 2011

Historical-comparative ecclesiology – Towards a comprehensive Practical Ecclesiology Practical Ecclesiology is a theological discipline, which opens up the possibility of a multi-disciplinary approach to ecclesiology. One aspect of such a multi-disciplinary Practical Ecclesiology is a historical-comparative approach. In this contribution an historical-comparative ecclesiology is developed under the headings of institutional, transformational and non-institutional ecclesiology. Practical Ecclesiology is normally practised from an empirical, strategic and hermeneutical perspective. This article argues that a historical perspective is essential to Practical Ecclesiology as it deepens our understanding of how the church evolved, transformed and adapted over centuries. This opens up important points of discussion in context of the 21st century.
Die Narratiewe terapie en die Gestalt terapie: ‘n Vergelyking tussen ‘n fenomenologiese eksistensiële benadering en ‘n sosiaal konstruksionistiese beskouing tot terapie
Authors: Delport Hein
Published: December 2011

The Narrative therapy and the Gestalt therapy: A comparison between a phemenological existensial approach and a social construction approach to therapy In this article the author takes a bird’s-eye view of the background and fundamentals of the narrative therapy as well as the Gestalt therapy to show similarities between these approaches in an attempt to establish a combined or complimentary approach to therapy.
Veterans and Veteran Families in General Education
Authors: Hawn Heather
Published: December 2011

There is little discussion as to the involvement of military students in higher education and their benefit to the classroom in the form of civic development and learning outcomes. The study suggests that all students benefit from these engagements but special considerations should be undertaken by creating positive learning environments.
How Pediatricians Can Deal with Children Who Have Been Sexually Abused by Family Members
Authors: Wolf Ruth
Published: December 2011

The present paper discusses children who have been the victims of sexual abuse in their own family. It focuses on the special role of pediatricians and medical staff in identifying such children and providing them with initial assistance by reporting the situation to the authorities. The first part of the paper surveys the short- and long-term effects of childhood sexual abuse, including the physical and emotional impact of sexual exploitation and severe neglect. This section discusses the symptoms shown by abused children, and how they express and deal with their trauma. It is extremely important for pediatricians to be sensitive to the possibility of patients being abused at home, as this is an area still largely regarded as a societal taboo. Also included in this section a discussion of the effects that are manifested when the victim has grown to adulthood, such as personality disorders. The second part of the paper deals with how pediatricians must act when they encounter such a situation in which they suspect sexual abuse in the family. They should strive to identify the problem and bring it to the attention of the authorities. Discovery of the problem is the most vital part of the path to the victim's recovery. The paper also discusses the aspect of treatment, advising doctors who encounter this problem on ways of dealing with it.
Enantioselective Reaction of Imines and Benzyl Nitriles Using Palladium Pincer Complexes with C2‐Symmetric Chiral Bis(imidazoline)s
Authors: Hyodo Kengo , Nakamura Shuichi , Tsuji Kotaro , Ogawa Takahiro , Funahashi Yasuhiro , Shibata Norio
Published: December 2011

Enantioselective reactions of a wide variety of benzyl nitriles with N‐tosylimines catalyzed by novel chiral 1,3‐bis(imidazolin‐2‐yl)benzene‐palladium(II) [Phebim‐Pd(II)] complexes have afforded the respective products in high yield with good enantioselectivity. A reaction mechanism is proposed based on X‐ray crystal structures of palladium complexes.
Intramolecular Carbonyl Nitroso Ene Reaction Catalyzed by Iron(III) Chloride/Hydrogen Peroxide as an Efficient Tool for Direct Allylic Amination
Authors: Atkinson Duncan , Kabeshov Mikhail A. , Edgar Mark , Malkov Andrei V.
Published: December 2011

A mild, simple oxidation protocol employing iron(III) chloride as a catalyst and hydrogen peroxide as a stoichiometric oxidant was found to be compatible with an intramolecular carbonyl nitroso ene reaction and allowed us to efficiently convert hydroxamic acids into a diverse range of 1,2‐ and 1,3‐amino alcohol derivatives in a single operation.
Thermodynamics of metal reactants for ammonia synthesis from steam, nitrogen and biomass at atmospheric pressure
Authors: Michalsky Ronald , Pfromm Peter H.
Published: December 2011

Catalytic ammonia synthesis at approximately 30 MPa and 800 K consumes about 5% of the global annual natural gas production causing significant CO2 emissions. A conceptual solar thermochemical reaction cycle to produce NH3 at near atmospheric pressure without natural gas is explored here and compared to solar thermochemical steam/air reforming to provide H2 used in the Haber‐Bosch process for NH3 synthesis. Mapping of Gibbs free energy planes quantifies the tradeoff between the yield of N2 reduction via metal nitridation, and NH3 liberation via steam hydrolysis vs. the temperatures required for reactant recovery from undesirably stable metal oxides. Equilibrium composition simulations suggest that reactants combining an ionic nitride‐forming element (e.g., Mg or Ce) with a transition metal (e.g., MgCr2O4, MgFe2O4, or MgMoO4) may enable the concept near 0.1 MPa (at maximum 64 mol % yield of Mg3N2 through nitridation of MgFe2O4 at 1,300 K, and 72 mol % of the nitrogen in Mg3N2 as NH3 during hydrolysis at 500 K). © 2011 American Institute of Chemical Engineers AIChE J, 58: 3203–3213, 2012
Novel insights in transport mechanisms and kinetics of phenylacetic acid and penicillin‐G in Penicillium chrysogenum
Authors: Douma Rutger D. , Deshmukh Amit T. , de Jonge Lodewijk P. , de Jong Bouke W. , Seifar Reza M. , Heijnen Joseph J. , van Gulik Walter M.
Published: December 2011

Although penicillin‐G (PenG) production by the fungus Penicillium chrysogenum is a well‐studied process, little is known about the mechanisms of transport of the precursor phenylacetic acid (PAA) and the product PenG over the cell membrane. To obtain more insight in the nature of these mechanisms, in vivo stimulus response experiments were performed with PAA and PenG in chemostat cultures of P. chrysogenum at time scales of seconds to minutes. The results indicated that PAA is able to enter the cell by passive diffusion of the undissociated acid at a high rate, but is at the same time actively excreted, possibly by an ATP‐binding cassette transporter. This results in a futile cycle, dissipating a significant amount of metabolic energy, which was confirmed by increased rates of substrate and oxygen consumption, and carbon dioxide production. To estimate the kinetic properties of passive import and active export of PAA over the cell membrane, a dynamic mathematical model was constructed. With this model, a good description of the dynamic data could be obtained. Also, PenG was found to be rapidly taken up by the cells upon extracellular addition, indicating that PenG transport is reversible. The measured concentration gradient of PenG over the cell membrane corresponded well with facilitated transport. Also, for PenG transport, a dynamic model was constructed and validated with experimental data. The outcome of the model simulations was in agreement with the presence of a facilitated transport system for PenG. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2012
D‐Ring‐Opened Phragmalin‐Type Limonoids from Chukrasia tabularis var. velutina
Authors: Luo Jun , Li Yi , Wang Jun‐Song , Kong Ling‐Yi
Published: December 2011

Five new D‐ring‐opened phragmalin‐type limonoids, tabulalins A–E (1–5, resp.), were isolated from the stem bark of Chukrasia tabularis var. velutina. In the structures of these new isolates, the D‐ring (C(16)/C(17) δ‐lactone ring) of phragmalins was cleaved, and rare C(16)/C(30) δ‐lactone ring in 1–3 or C(16)/C(8) γ‐lactone ring in 4 and 5 were formed. The structures of these new compounds were elucidated based on extensive 1D‐ and 2D‐spectroscopic analyses (HSQC, HMBC, and ROESY) and HR‐ESI‐MS. The major compounds, 2, 3, and 5, were evaluated for their inhibitory activities against lipopolysaccharide (LPS)‐induced nitric oxide (NO) production in a macrophage (RAW264.7) cell line with IC50 values of 15.3±0.6, 13.0±0.5, and 17.1±0.7 μM, respectively.
‘Tocol‐omic’ Diversity in Wild Barley, Short Communication
Authors: Shen Yu , Lebold Katie , Lansky Ephraim Philip , Traber Maret G. , Nevo Eviatar
Published: December 2011

Hordeum spontaneum, wild barley, is the direct progenitor of domestic barley, Hordeum vulgare, an economically important ingredient of animal feed, beer, soy sauce, and more recently, of nutraceuticals. Domestic barley has also been used in the past as a medicine. Barley is a rich source of tocotrienols, with α‐tocotrienol being the most prevalent. Wild barley seeds were harvested from ecogeographically diverse areas across the Fertile Crescent, and the tocopherol (α–δ) and tocotrienol (α–δ) contents were determined. Diversity differences in individual and total ‘tocol’ values were significant between and within specific countries, and were significantly correlated with temperature. Wild barley may be used in the future to improve functional qualities of domestic barley. ‘Tocolome’ and ‘tocolomics’ are proposed to encompass all tocols and potentially synergy‐enhancing ‘entourage’ compounds that may occur in tocols' ‘metabolomic neighborhoods’, aiding the standardized manufacture of complex barley derivatives for nutraceutical and pharmaceutical functions.
Variation in Physical and Chemical Characteristics of Common Bean (Phaseolus vulgaris L.) Grain along a Domestication Gradient
Authors: Peña‐Valdivia Cecilia Beatriz , García‐Nava J. Rodolfo , Aguirre R J. Rogelio , Ybarra‐Moncada Ma. Carmen , López H Maritza
Published: December 2011

The objective of this study was to compare six samples of Mexican wild common bean (Phaseolus vulgaris L.) against three landraces and three improved cultivars with respect to physical and chemical attributes, and the culinary quality potential of their grain. A completely randomized experimental design was used to characterize the twelve genotypes. Data were analyzed by analysis of variance and pair‐wise comparison of the treatment means by the Tukey test. In addition, correlation and principal‐component analysis (PCA) were carried out using twelve characteristics of raw and four of cooked wild and domesticated grains. The results show a larger variability of the physical and chemical characteristics in wild than in domesticated beans. The PCA confirmed that grain gigantism was the main physical characteristic resulting of domestication, whereas the protein and tryptophan contents tended to be higher in wild than domesticated genotypes. Some wild samples from Chihuahua and Durango, Mexico, showed to be a genetic resource to improve food quality, because of their richness in minerals, protein, lysine, tryptophan, and dietary fibers.
Intracolonial Allocation of Trisoxazole Macrolides in the Sponge Pachastrissa nux
Authors: Sirirak Thanchanok , Intaraksa Niwan , Kaewsuwan Sireewan , Yuenyongsawad Supreeya , Suwanborirux Khanit , Plubrukarn Anuchit
Published: December 2011

Pachastrissa nux has two distinctive growth forms in one colony, i.e., the protruding gorgonian‐shaped capitum and the substratum‐attached irregular‐shaped base. The sponge has the ability to allocate specifically its major secondary metabolites to the two parts in different levels. Using two cytotoxic trisoxazole macrolides, kabiramides C (2) and G (3), as chemical markers, it was found that the capitum accumulated higher contents of either or both compounds than did the base. However, there were neither inductive nor suppressive correlations among the allocation profiles of either compound in either part of the sponge. The allocation of kabiramides was a trade‐off with the structural materials involved in reinforcing the strength of the sponge. To date, this is the second report that provides evidence of the specific allocation of bioactive metabolites in two distinctively different organ‐like structures in a single sponge colony.
Vacuum thrombectomy of large right atrial thrombus
Authors: Dudiy Yuriy , Kronzon Itzhak , Cohen Howard A. , Ruiz Carlos E.
Published: December 2011

We report a novel technique for percutaneous removal of the right heart thrombi using a suction cannula. This method allowed complete en bloc removal of the right atrial thrombus avoiding surgical procedure in a high risk patient. © 2011 Wiley Periodicals, Inc.
Electron Correlation in Real Time
Authors: Sansone Giuseppe , Pfeifer Thomas , Simeonidis Konstantinos , Kuleff Alexander I.
Published: December 2011

Electron correlation, caused by the interaction among electrons in a multielectron system, manifests itself in all states of matter. A complete theoretical description of interacting electrons is challenging; different approximations have been developed to describe the fundamental aspects of the correlation that drives the evolution of simple (few‐electron systems in atoms/molecules) as well as complex (multielectron wave functions in atoms, molecules, and solids) systems. Electron correlation plays a key role in the relaxation mechanisms that characterize excited states of neutral or ionized atoms and molecules populated by absorption of extreme ultraviolet (XUV) or X‐ray radiation. The dynamics of these states can lead to different processes such as Fano resonance and Auger decay in atoms or interatomic Coulombic decay or charge migration in molecules and clusters. Many of these relaxation mechanisms are ubiquitous in nature and characterize the interaction of complex systems, such as biomolecules, adsorbates on surfaces, and hydrogen‐bonded clusters, with XUV light. These mechanisms evolve typically on the femtosecond (1 fs=10−15 s) or sub‐femtosecond timescale. The experimental availability of few‐femtosecond and attosecond (1 as=10−18 s) XUV pulses achieved in the last 10 years offers, for the first time, the opportunity to excite and probe in time these dynamics giving the possibility to trace and control multielectron processes. The generation of ultrashort XUV radiation has triggered the development and application of spectroscopy techniques that can achieve time resolution well into the attosecond domain, thereby offering information on the correlated electronic motion and on the correlation between electron and nuclear motion. A deeper understanding of how electron correlation works could have a large impact in several research fields, such as biochemistry and biology, and trigger important developments in the design and optimization of electronic devices.
Chemical Etching of Zinc Oxide for Thin‐Film Silicon Solar Cells
Authors: Hüpkes Jürgen , Owen Jorj I. , Pust Sascha E. , Bunte Eerke
Published: December 2011

Chemical etching is widely applied to texture the surface of sputter‐deposited zinc oxide for light scattering in thin‐film silicon solar cells. Based on experimental findings from the literature and our own results we propose a model that explains the etching behavior of ZnO depending on the structural material properties and etching agent. All grain boundaries are prone to be etched to a certain threshold, that is defined by the deposition conditions and etching solution. Additionally, several approaches to modify the etching behavior through special preparation and etching steps are provided.
Ecogeomorphic expressions of an aspect‐controlled semiarid basin: I. Topographic analyses with high‐resolution data sets
Authors: Gutiérrez‐Jurado Hugo A. , Vivoni Enrique R.
Published: December 2011

Understanding vegetation effects on hydrogeomorphic processes requires detailed studies at the catchment scale using high‐resolution topographic data. We perform topographic analyses in a semiarid basin in central New Mexico with opposing north and south facing slopes. Utilizing a set of terrain metrics, we explore the impact of topographic resolution and quality from three digital elevation models (DEMs): (1) Interferometric Synthetic Aperture Radar (10 m); (2) differential Global Positioning System (4 m); and (3) Light Detection And Ranging (LiDAR, 1 m). The sequentially improved terrain data sets progressively reveal topographic and geomorphic differences in north and facing hillslopes associated with vegetation contrasts. For example, we found less frequent fluvial erosion in the more mesic, north facing slope with a juniper‐grass ecosystem as compared with a more xeric, south facing slope with a desert shrubland. Furthermore, the high‐resolution LiDAR data also revealed weakly steeper south facing slopes, contradicting previous work with coarser topographic products. A sensitivity analysis revealed that hillslope diffusion occurs in north facing ecosystems because of relatively higher slope, whereas fluvial erosion in the south facing ecosystem is a result of large contributing areas. The use of LiDAR data also discriminates statistically between different sediment transport regimes in the north and south facing slopes because of different dominant factors. Improvements in the definition of ecogeomorphic properties from LiDAR point to the need for high‐resolution DEMs for assessing vegetation–hydrogeomorphic interactions at the catchment and hillslope scales. Copyright © 2011 John Wiley & Sons, Ltd.
Effect of throughfall variability on recharge: application to hemlock and deciduous forests in western Massachusetts
Authors: Guswa Andrew J. , Spence Caitlin M.
Published: December 2011

Vegetation canopies intercept and redistribute precipitation in space. Although throughfall patterns are challenging to correlate with plant characteristics, many studies have shown that the spatial patterns persist through time. This persistence leads to wet and dry spots that can affect recharge, transpiration, and other nonlinear ecohydrologic and biogeochemical processes. A stochastic framework is used to determine the effect of throughfall variability on hydrologic fluxes. Throughfall variability increases and concentrates recharge, and the magnitude of the effect depends on the character of throughfall variability along with characteristics of climate, soil, and vegetation.

This framework is also used to explore specific differences in summertime recharge between stands of deciduous trees (birch, maple, and oak) and eastern hemlock (Tsuga canadensis). Throughout the eastern United States, the invasive hemlock woolly adelgid poses a significant threat to hemlock forests, and replacement of hemlock forests by other species has the potential to alter hydrologic fluxes and other processes. Field investigations in 2009 and 2010 indicate that, relative to deciduous stands, hemlock canopies intercept more water and tend to produce dry rather than wet spots. Although deciduous stands produce more throughfall, model results indicate that differences in canopy interception are outweighed by large differences in peak transpiration rates, and predictions of summertime recharge are lower in deciduous forests than in hemlock. Copyright © 2011 John Wiley & Sons, Ltd.
Anatomical and functional overlap within the insula and anterior cingulate cortex during interoception and phobic symptom provocation
Authors: Caseras Xavier , Murphy Kevin , Mataix‐Cols David , López‐Solà Marina , Soriano‐Mas Carles , Ortriz Hector , Pujol Jesus , Torrubia Rafael
Published: December 2011

The anterior insula and the dorsal anterior cingulate cortex (ACC) are regarded as key brain structures associated with the integration of perceived phobic characteristics of external stimuli and the perception of ones own body responses that leads to emotional feelings. To test to what extent the activity in these two brain structures anatomically and functionally overlap during phobic reactions and interoception, we submitted the same group of phobic participants (n = 29; either spider or blood‐injection‐injury (BII) phobics) and controls (n = 17) to both type of experimental paradigms. Results showed that there was a clear anatomical overlap in the Blood Oxygen Level‐Dependent (BOLD) responses within the anterior insula and ACC elicited during phobic symptom provocation and during interoceptive awareness. The activity within these two brain structures also showed to be correlated in the spider phobia group, but not in the BII phobic participants. Our results seem to support the idea that the activity within these two brain areas would be associated with the integration of perceived stimuli characteristics and bodily responses that lead to what we label as “fear.” However, that seems not to be the case in BII phobia, where more research is needed in order to clarify to what extent that could be associated with the idiosyncratic physiological response that these patients present in front of phobic stimuli (i.e., drop in heart rate and blood pressure). Hum Brain Mapp, 2013. © 2011 Wiley Periodicals, Inc.
HDAC activity is required for BDNF to increase quantal neurotransmitter release and dendritic spine density in CA1 pyramidal neurons
Authors: Calfa Gaston , Chapleau Christopher A. , Campbell Susan , Inoue Takafumi , Morse Sarah J. , Lubin Farah D. , Pozzo‐Miller Lucas
Published: December 2011

Molecular mechanisms involved in the strengthening and formation of synapses include the activation and repression of specific genes or subsets of genes by epigenetic modifications that do not alter the genetic code itself. Chromatin modifications mediated by histone acetylation have been shown to be critical for synaptic plasticity at hippocampal excitatory synapses and hippocampal‐dependent memory formation. Considering that brain‐derived neurotrophic factor (BDNF) plays an important role in synaptic plasticity and behavioral adaptations, it is not surprising that regulation of this gene is subject to histone acetylation changes during synaptic plasticity and hippocampal‐dependent memory formation. Whether the effects of BDNF on dendritic spines and quantal transmitter release require histone modifications remains less known. By using two different inhibitors of histone deacetylases (HDACs), we describe here that their activity is required for BDNF to increase dendritic spine density and excitatory quantal transmitter release onto CA1 pyramidal neurons in hippocampal slice cultures. These results suggest that histone acetylation/deacetylation is a critical step in the modulation of hippocampal synapses by BDNF. Thus, mechanisms ofepigenetic modulation of synapse formation and function are novel targets to consider for the amelioration of symptoms of intellectual disabilities and neurodegenerative disorders associated with cognitive and memory deficits. © 2011 Wiley Periodicals, Inc.
Polyhydroxypregnane Glycosides from the Roots of Cynanchum otophyllum
Authors: Ma Lie‐Feng , Shan Wei‐Guang , Zhan Zha‐Jun
Published: December 2011

Six new polyhydroxypregnane glycosides, namely cynotophyllosides A–F (1–6), together with five known steroids, were isolated from the roots of Cynanchum otophyllum. Their structures were elucidated by extensive spectroscopic methods (especially 2D‐NMR techniques) and acid‐catalyzed hydrolysis. Furthermore, high field 1D‐ and 2D‐NMR experiments were employed to elucidate the structure of 8 previously deduced only on the basis of LC/MS data.
Baeckeins A and B, Two Novel 6‐Methylflavonoids from the Roots of Baeckea frutescens
Authors: Jia Bei‐Xi , Yang Jie , Chen Xiao‐Qing , Cao Yuan , Lai Mao‐Xiang , Wang Qiang
Published: December 2011

A pair of novel isomeric 6‐methylflavonoids, named baeckeins A (1) and B (2), were isolated from the roots of Baeckea frutescens. The two compounds possess a unique C23 skeleton, resulting from the 6‐methylation and 8‐arylation of a flavonol (=3‐hydroxy‐2‐phenyl‐4H‐1‐benzopyran‐4‐one) framework and the formation of an unusual lactone ring E. Their structures were elucidated by detailed spectroscopic analyses, including HR‐ESI‐MS and 1D‐ and 2D‐NMR data (HSQC, HMBC, and ROESY). A plausible biogenetic pathway for compounds 1 and 2 is also proposed (Scheme).
Synthesis, Characterization, X‐Ray Structural Analysis, and Iodination Ability of Benzyl(triphenyl)phosphonium Dichloroiodate
Authors: Imanieh Hossein , Ghammamy Shahriar , Nikje Mir Mohammad Alavi , Hosseini Farhang , Aghbolagh Zahra Shokri , Fun Hoong‐Kun , Khavasi Hamid Reza , Kia Reza
Published: December 2011

Benzyl(triphenyl)phosphonium dichloroiodate (BTPPICl2), BnPh3P+(ICl2)−, is easily synthesized in a nearly quantitative yield by the addition of BnPh3P+Cl− to a CH2Cl2 solution of iodine monochloride (ICl). BnPh3P+Cl− can be prepared by the reaction of Ph3P and BnCl. The compound was characterized by physicochemical and spectroscopic methods (elemental analysis, FT‐IR, and 1H‐NMR). The use of phosphonium counterion improves the quality of the BTPPICl2 crystals. BTPPICl2 crystallizes in the monoclinic system, and its crystal and molecular structure has been determined at 100(1) K by X‐ray diffraction. The structure was solved by the direct method and had refined R value of 0.0637 for 699 reflections (I>2σ(I)), space group P21/n with a=12.4700(3), b=13.2196(3), c=14.4580(3) Å, β=102.6340(10)°, V=2325.67(9) Å3, and Z=4. The I‐atom is coordinated by two Cl‐atoms as ligands in a linear geometry. This compound is a versatile reagent for the efficient and selective iodination of organic substrates, in particular of aromatic phenols to the corresponding iodo compounds, under mild conditions. To assess the generality of method, a wide variety of phenols with electron‐donating and electron‐withdrawing substituents were studied. BTPPICl2 is a mild iodination reagent, which offers a new avenue for an expeditious iodination of phenols. The inexpensive, relatively non‐toxic reagent, and mild conditions are the positive features of the procedure and reagent.
Toxicological risks to humans of toxaphene residues in fish
Authors: Leonards Pim EG , Besselink Harrie , Klungsøyr Jarle , McHugh Brendan , Nixon Eugene , Rimkus Gerhard G , Brouwer Abraham , de Boer Jacob
Published: December 2011

A revised risk assessment for toxaphene was developed, based on the assumption that fish consumers are only exposed to toxaphene residues that differ substantially from technical toxaphene due to environmental degradation and metabolism. In vitro studies confirmed that both technical toxaphene and degraded toxaphene inhibit gap junctional intercellular communication that correlates with the mechanistic potential to cause tumor promotion. In vivo rat studies established the NOAEL for degraded and technical toxaphene at the highest dose tested in the bioassay. Toxaphene residue intakes from European fishery products were estimated and compared to the provisional tolerable daily intakes (TDIs) from various regulatory agencies including Canada, the United States, and Germany. The estimated intake was also compared to a new calculated provisional MATT pTDI. The MATT pTDI is based on new toxicological information (in vivo rat studies) developed on a model for environmental toxaphene residues rather than technical toxaphene. A MATT pTDI (1.08 mg total toxaphene for a person of 60 kg) for tumor promotion potency was adopted for use in Europe and is referred to here as the MATT pTDI. These new data result in a better estimate of safety and a higher TDI than previously used. Based on realistic fish consumption data and recent baseline concentration data of toxaphene in European fishery products, the toxaphene intake for the consumers of Germany, Ireland, Norway, and the Netherlands was estimated. For an average adult fish consumer, the average daily intake of toxaphene was estimated to be 1.2, 0.4, 0.5, and 0.2 µg for the consumers of Norway, Germany, Ireland, and the Netherlands, respectively. The toxaphene intake of these average fish consumers was far below the MATT pTDI of 1.08 mg/60 kg bw. In conclusion, based on the most relevant toxicological studies and the most realistic estimates of fish consumption and recent concentrations of toxaphene in European fishery products, adverse health effects are unlikely for the average European consumer of fishery products. In no case is the MATT pTDI exceeded. Integr Environ Assess Manag 2012; 8: 523–529. © SETAC
VEGF-independent cell-autonomous functions of HIF-1α regulating oxygen consumption in fetal cartilage are critical for chondrocyte survival
Authors: Maes Christa , Araldi Elisa , Haigh Katharina , Khatri Richa , Van Looveren Riet , Giaccia Amato J , Haigh Jody J , Carmeliet Geert , Schipani Ernestina
Published: December 2011

Fetal growth plate cartilage is nonvascularized, and chondrocytes largely develop in hypoxic conditions. We previously found that mice lacking the hypoxia-inducible transcription factor HIF-1α in cartilage show massive death of centrally located, hypoxic chondrocytes. A similar phenotype was observed in mice with genetic ablation of either all or specifically the diffusible isoforms of vascular endothelial growth factor (VEGF), a prime angiogenic target of HIF-1α. Here, we assessed whether VEGF is a critical downstream component of the HIF-1α–dependent survival pathway in chondrocytes. We used a genetic approach to conditionally overexpress VEGF164 in chondrocytes lacking HIF-1α, evaluating potential rescuing effects. The effectiveness of the strategy was validated by showing that transgenic expression of VEGF164 in Col2-Cre;VEGFf/f mice stimulated angiogenesis in the perichondrium, fully corrected the excessive hypoxia of VEGF-deficient chondrocytes, and completely prevented chondrocyte death. Yet, similarly crossed double-mutant embryos lacking HIF-1α and overexpressing VEGF164 in the growth plate cartilage still displayed a central cell death phenotype, albeit slightly delayed and less severe compared with mice exclusively lacking HIF-1α. Transgenic VEGF164 induced massive angiogenesis in the perichondrium, yet this only partially relieved the aberrant hypoxia present in HIF-1α–deficient cartilage and thereby likely inflicted only a partial rescue effect. In fact, excessive hypoxia and failure to upregulate phosphoglycerate-kinase 1 (PGK1), a key enzyme of anaerobic glycolytic metabolism, were among the earliest manifestations of HIF-1α deficiency in cartilaginous bone templates, and reduced PGK1 expression was irrespective of transgenic VEGF164. These findings suggest that HIF-1α activates VEGF-independent cell-autonomous mechanisms to sustain oxygen levels in the challenged avascular cartilage by reducing oxygen consumption. Hence, regulation of the metabolic pathways by HIF-1α and VEGF-dependent regulation of angiogenesis coordinately act to maintain physiological cartilage oxygenation. We conclude that VEGF and HIF-1α are critical preservers of chondrocyte survival by ensuring an adequate balance between availability and handling of oxygen in developing growth cartilage. © 2012 American Society for Bone and Mineral Research