bluuebunny/crossref_metadata_2025 huggingface dataset:
Human umbilical cord Wharton's jelly stem cells and its conditioned medium support hematopoietic stem cell expansion ex vivo
Authors: Fong C.Y. , Gauthaman K. , Cheyyatraivendran S. , Lin H.D. , Biswas A. , Bongso A.
Published: October 2011

Bone marrow mesenchymal stromal cells (BMMSCs) have been used as feeder support for the ex vivo expansion of hematopoietic stem cells (HSCs) but have the limitations of painful harvest, morbidity, and risk of infection to the patient. This prompted us to explore the use of human umbilical cord Wharton's jelly MSCs (hWJSCs) and its conditioned medium (hWJSC‐CM) for ex vivo expansion of HSCs in allogeneic and autologous settings because hWJSCs can be harvested in abundance painlessly, are proliferative, hypoimmunogenic, and secrete a variety of unique proteins. In the presence of hWJSCs and hWJSC‐CM, HSCs put out pseudopodia‐like outgrowths and became highly motile. Time lapse imaging showed that the outgrowths helped them to migrate towards and attach to the upper surfaces of hWJSCs and undergo proliferation. After 9 days of culture in the presence of hWJSCs and hWJSC‐CM, MTT, and Trypan blue assays showed significant increases in HSC numbers, and FACS analysis generated significantly greater numbers of CD34+ cells compared to controls. hWJSC‐CM produced the highest number of colonies (CFU assay) and all six classifications of colony morphology typical of hematopoiesis were observed. Proteomic analysis of hWJSC‐CM showed significantly greater levels of interleukins (IL‐1a, IL‐6, IL‐7, and IL‐8), SCF, HGF, and ICAM‐1 compared to controls suggesting that they may be involved in the HSC multiplication. We propose that cord blood banks freeze autologous hWJSCs and umbilical cord blood (UCB) from the same umbilical cord at the same time for the patient for future ex vivo HSC expansion and cell‐based therapies. J. Cell. Biochem. 113: 658–668, 2012. © 2011 Wiley Periodicals, Inc.
A systems biology approach to identify molecular pathways altered by HDAC inhibition in osteosarcoma
Authors: Wittenburg Luke A. , Ptitsyn Andrey A. , Thamm Douglas H.
Published: October 2011

Osteosarcoma (OS) is the most common primary tumor in humans and dogs affecting the skeleton, and spontaneously occurring OS in dogs serves as an extremely useful model. Unacceptable toxicities using current treatment protocols prevent further dose‐intensification from being a viable option to improve patient survival and thus, novel treatment strategies must be developed. Histone deacetylase inhibitors (HDACi) have recently emerged as a promising class of therapeutics demonstrating an ability to enhance the anti‐tumor activity of traditional chemotherapeutics. To date, gene expression analysis of OS cell lines treated with HDACi has not been reported, and evaluation of the resultant gene expression changes may provide insight into the mechanisms that lead to success of HDACi. Canine OS cells, treated with a clinically relevant concentration of the HDACi valproic acid (VPA), were used for expression analysis on the Affymetrix canine v2.0 genechip. Differentially expressed genes were grouped into pathways based upon functional annotation; pathway analysis was performed with MetaCore and Ingenuity Pathways Analysis software. Validation of microarray results was performed by a combination of qRT‐PCR and functional/biochemical assays revealing oxidative phosphorylation, cytoskeleton remodeling, cell cycle, and ubiquitin‐proteasome among those pathways most affected by HDACi. The mitomycin C‐bioactivating enzyme NQ01 also demonstrated upregulation following VPA treatment, leading to synergistic reductions in cell viability. These results provide a better understanding of the mechanisms by which HDACi exert their effect in OS, and have the potential to identify biomarkers that may serve as novel targets and/or predictors of response to HDACi‐containing combination therapies in OS. J. Cell. Biochem. 113: 773–783, 2012. © 2011 Wiley Periodicals, Inc.
Ab initio characterization of size dependence of electronic spectra for linear anionic carbon clusters Cn− (n = 4–17)
Authors: Guo Xu‐Geng , Zhang Jing‐Lai , Zhao Yuan
Published: October 2011

In this article, we determine the ground‐state equilibrium geometries of the linear anionic carbon clusters C (n = 4–17) by means of the density functional theory B3LYP, CAM‐B3LYP, and coupled cluster CCSD(T) calculations, as well as their electronic spectra obtained by the multireference second‐order perturbation theory CASPT2 method. These studies indicate that these linear anions possess doublet 2∏g or 2∏u ground state, and the even‐numbered clusters are generally acetylenic, whereas the odd‐numbered ones are essentially cumulenic. The energy differences, electron affinities, and incremental binding energies of C chains all exhibit a notable tread of parity alternation, with n‐even chains being more stable than n‐odd ones. In addition, the predicted vertical excitation energies from the ground state to four low‐lying excited states are in reasonably good agreement with the available experimental observations, and the calculations for the higher excited electronic transitions can provide accurate information for the experimentalists and spectroscopists. Interestingly, the absorption wavelengths of the 12∏u/g ← X2∏g/u transitions of the n‐even clusters show a nonlinear trend of exponential growth, whereas those of the n‐odd counterparts are found to obey a linear relationship as a function of the chain size, as shown experimentally. Moreover, the absorption wavelengths of the transitions to the higher excited states of C series have the similar linear size dependence as well. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011
Tritiated dihydro compounds employed as radioligand surrogates
Authors: Filer Crist N.
Published: October 2011

Often, biologically useful olefin‐containing substances cannot easily be tritium labeled without concomitant olefin reduction. This review explores those instances where tritiated dihydro analogues of these compounds have been used in lieu of the less accessible radiolabeled parent structures. Copyright © 2011 John Wiley & Sons, Ltd.
[18F]Fluoride recovery via gaseous [18F]HF
Authors: Mathiessen Bente , Jensen Mikael , Zhuravlev Fedor
Published: October 2011

Acidification of target water with H2SO4 in a specially constructed glassy carbon/polyethylene apparatus allowed for recovery of up to 82% of [18F]fluoride as [18F]HF gas. The [18F]HF distillate was found to be acid‐free but moist; when passed through a solution of tBuPh2SiOTf, it yielded [18F]tBuPh2SiF. The multivariate design of experiment showed that the key to high yield of [18F]HF was the efficient degassing of the reaction mixture.
Müller glial cells induce stem cell properties in retinal progenitors in vitro and promote their further differentiation into photoreceptors
Authors: Simón María V. , De Genaro Pablo , Abrahan Carolina E. , de los Santos Beatriz , Rotstein Nora P. , Politi Luis E.
Published: October 2011

Using stem cells to replace lost neurons is a promising strategy for treating retinal neurodegenerative diseases. Among their multiple functions, Müller glial cells are retina stem cells, with a robust regenerative potential in lower vertebrates, which is much more restricted in mammals. In rodents, most retina progenitors exit the cell cycle immediately after birth, differentiate as neurons, and then cannot reenter the cell cycle. Here we demonstrate that, in mixed cultures with Müller glial cells, rat retina progenitor cells expressed stem cell properties, maintained their proliferative potential, and were able to preserve these properties and remain mitotically active after several consecutive passages. Notably, these progenitors retained the capacity to differentiate as photoreceptors, even after successive reseedings. Müller glial cells markedly stimulated differentiation of retina progenitors; these cells initially expressed Crx and then developed as mature photoreceptors that expressed characteristic markers, such as opsin and peripherin. Moreover, they were light responsive, insofar as they decreased their cGMP levels when exposed to light, and they also showed high‐affinity glutamate uptake, a characteristic of mature photoreceptors. Our present findings indicate that, in addition to giving rise to new photoreceptors, Müller glial cells might instruct a pool of undifferentiated cells to develop and preserve stem cell characteristics, even after successive reseedings, and then stimulate their differentiation as functional photoreceptors. This complementary mechanism might contribute to enlarge the limited regenerative capacity of mammalian Müller cells. © 2011 Wiley Periodicals, Inc.
Postnatal morphine administration alters hippocampal development in rats
Authors: Traudt Christopher M. , Tkac Ivan , Ennis Kathleen M. , Sutton Leah M. , Mammel Daniel M. , Rao Raghavendra
Published: October 2011

Morphine is frequently used as an analgesic and sedative in preterm infants. Adult rats exposed to morphine have an altered hippocampal neurochemical profile and decreased neurogenesis in the dentate gyrus of the hippocampus. To evaluate whether neonatal rats are similarly affected, rat pups were injected twice daily with 2 mg/kg morphine or normal saline from postnatal days 3 to 7. On postnatal day 8, the hippocampal neurochemical profile was determined using in vivo 1H NMR spectroscopy. The mRNA and protein concentrations of specific analytes were measured in hippocampus, and cell division in dentate gyrus was assessed using bromodeoxyuridine. The concentrations of γ‐aminobutyric acid (GABA), taurine, and myo‐insotol were decreased, whereas concentrations of glutathione, phosphoethanolamine, and choline‐containing compounds were increased in morphine‐exposed rats relative to control rats. Morphine decreased glutamic acid decarboxylase enzyme levels and myelin basic protein mRNA expression in the hippocampus. Bromodeoxyuridine labeling in the dentate gyrus was decreased by 60–70% in morphine‐exposed rats. These results suggest that recurrent morphine administration during brain development alters hippocampal structure. © 2011 Wiley Periodicals, Inc.
Insufficient endogenous redox buffer capacity may underlie neuronal vulnerability to cerebral ischemia and reperfusion
Authors: Röhnert Peter , Schröder Ulrich H. , Ziabreva Iryna , Täger Michael , Reymann Klaus G. , Striggow Frank
Published: October 2011

Reactive oxygen species (ROS) are key players in ischemia‐induced neurodegeneration. We investigated whether hippocampal neurons may lack sufficient redox‐buffering capacity to protect against ROS attacks. Using organotypic hippocampal slice cultures (OHSCs) transiently exposed to oxygen and glucose deprivation (OGD) and gerbils suffering from a two‐vessel occlusion (2VO) as complementary ex vivo and in vivo models, we have elucidated whether the intrinsic redox systems interfere with ischemia‐induced neurodegeneration. Cell‐ type‐specific immunohistological staining of hippocampal slice cultures revealed that pyramidal neurons, in contrast to astrocytes and microglia, express free thiols only weakly. In addition, free thiol levels were extensively decreased throughout the hippocampal formation immediately after OGD, but recovered within 24 hr after reperfusion. In parallel, progressive glia activation and proliferation were observed. Increased neuronal exposure to ROS was monitored by dihydroethidium oxidation in hippocampal pyramidal cell layers immediately after OGD. Coadministration of reduction equivalents (α‐lipoic acid) and thiol‐stimulating agents (enalapril, ambroxol) decreased ischemia‐induced neuronal damage in OGD‐treated OHSCs and in gerbils exposed to 2VO, whereas single drug applications remained ineffective. In summary, limited redox buffering capacities of pyramidal neurons may underlie their exceptional vulnerability to cerebral ischemia. Consistently, multidrug treatments supporting endogenous redox systems may offer a strategy to promote valid neuroprotection. © 2011 Wiley Periodicals, Inc.
When does adaptive performance lead to higher task performance?
Authors: Shoss Mindy K. , Witt L. A. , Vera Dusya
Published: October 2011

Adaptive performance is a facet of performance that reflects acquiring enhanced competencies in response to change. Micro‐level researchers have assumed that adaptive performance is beneficial for task performance. Similarly, macro‐level researchers have suggested that organizations need to attend to, monitor, and respond to contingencies in their environments for adaptive performance to be beneficial for firm performance. Drawing from the attention‐based theory of the firm and resource theory, we suggest that perceptions of organizational politics and individual differences in conscientiousness constitute contingencies of the adaptive performance–task performance relationship. In a sample of 92 call center employees, we found that adaptive performance is positively associated with task performance but that conscientiousness and organizational politics jointly influence the adaptive performance–task performance relationship. Copyright © 2011 John Wiley & Sons, Ltd.
Analysis of dry periods along a pluviometric gradient in Mediterranean southern Spain
Authors: Ruiz‐Sinoga J. D. , Garcia‐Marin R. , Gabarron‐Galeote M. A. , Martinez‐Murillo J. F.
Published: October 2011

In southern Spain a longitudinal pluviometric gradient occurs under Mediterranean climatic conditions in an area that has at least two months of drought each year and very irregular rainfall. From the Strait of Gibraltar to the Cabo de Gata in Almería there is a reduction of more than 1,000 mm year−1 in the mean annual rainfall. Analysis of the frequency and intensity of drought periods is necessary in regions where water resources are scarce and the ecosystem is highly dependent on water availability. Drought periods in the region described above were analysed using the DDSLR (Dry Days Since Last Rain) index to i) characterize trends in number of dry days and the amount of rainfall along the pluviometric gradient, ii) assess how the DDSLR index changes along the gradient from semiarid to humid Mediterranean regions, and iii) contribute to studies addressing the importance of climatic gradients in relation to the dynamics of various ecosystems. The DDSLR method enables calculation of the probability of the occurrence of dry days (days without rain) at any time of the year, assessment of the risk of water deficits for vegetation during plant growth periods, and evaluation of the temporal variability of hydrological/geomorphological processes that depend on soil moisture throughout the year. The results showed that there is a critical period of rainfall scarcity during September and October, which has implications for the availability of soil water resources for vegetation.

In short‐term, the major problems are predicted for the Spanish Southern Mediterranean due to the increasing irregularity in precipitations: the number of days with no rains and drought periods are increased, but also a significant increment in the probabilities of extreme rainfalls exceeding 30 mm day−1. Copyright © 2011 Royal Meteorological Society
Simultaneous determination of eight active components in Houttuynia cordata injection and its quality control in productive process
Authors: Ji Wei , Bi Kaishun , Chen Qianqian , Jiang Lingyan , Liang Ke , Li Qing
Published: October 2011

A simple, reliable and effective gas chromatography coupled with flame ionization detection method was developed for the simultaneous determination of eight components (α‐pinene, β‐pinene, myrcene, limonene, terpinen‐4‐ol, α‐terpineol, bornyl acetate and methyl‐n‐nonylketone) in Chinese medicine Houttuynia cordata and its injection. The chromatographic separation of all eight components, including undecylene as internal standard was performed on a DB‐1 column (30 m×0.25 mm, 0.25 μm). Excellent linear behaviors including herb and injection over the investigated concentration ranges were observed with the values of r2 higher than 0.9990 for all analytes. Satisfactory intra‐day and inter‐day precisions were achieved with RSD less than 2% and the average recoveries for all analytes at three different concentrations obtained were in the range of 93.4–104.4%, with RSD ranging from 1.3 to 4.1%. The proposed method was successfully applied in the simultaneous determination of these active components in H. cordata and H. cordata injection (HCI), including the intermediate product of HCI in productive process, from different pharmaceutical factories and different production batches, indicating that the method in this paper was particularly suitable for the routine analysis of HCI and its quality control in productive process.
Separation of monosaccharides by solid‐phase extraction with ionic liquid‐modified microporous polymers
Authors: Tian Minglei , Bi Wentao , Row Kyung H.
Published: October 2011

Ionic liquid‐modified porous polymers with large surface area and large amount of functional groups were developed and used in SPE to separate four monosaccharides. Adsorption isotherm showed that the sorbent with amino ionic liquid groups had the highest interaction with the target compounds. The mobile phase of acetonitrile/water 85:15 and 73:30 v/v can successfully separate the monosaccharides. The sorbent produced reproducible results and performed stably, demonstrating its potential applicability in the separation of extract from natural plant.
The complexity of countable categoricity in finite languages
Authors: Ivanov Aleksander
Published: October 2011

We study complexity of the index set of countably categorical theories and Ehrenfeucht theories in finite languages.
Kinetic Analysis of the Amphiphilic Star Block Copolymerization
Authors: Zhou Zhiping , Yan Deyue
Published: October 2011

A kinetic model of the amphiphilic star block copolymerization is developed. The star polymer species, resulting from star polymerization with dendrimer cores and hydrophobic monomers, are used as macroinitiators and initiate the graft polymerization of the hydrophilic monomers. Analytical expressions for the size distributions for the species formed in every step are derived. The method with monomers added to the reaction system in batches decreases the polydispersity index for the products obtained. It reaches a minimum if the monomer feed quantity is equal in every step. Therefore, the dimension and structure of the amphiphilic star block copolymers produced can be designed by using the proposed kinetic mechanism.

magnified image
Objective detection of sting jets in low‐resolution datasets
Authors: Martínez‐Alvarado Oscar , Gray Suzanne L. , Clark Peter A. , Baker Laura H.
Published: October 2011

Sting jets are transient coherent mesoscale strong wind features that can cause damaging surface wind gusts in extratropical cyclones. Currently, we have only limited knowledge of their climatological characteristics. Numerical weather prediction models require enough resolution to represent slantwise motions with horizontal scales of tens of kilometres and vertical scales of just a few hundred metres to represent sting jets. Hence, the climatological characteristics of sting jets and the associated extratropical cyclones cannot be determined by searching for sting jets in low‐resolution datasets such as reanalyses.

A diagnostic is presented and evaluated for the detection in low‐resolution datasets of atmospheric regions from which sting jets may originate. Previous studies have shown that conditional symmetric instability (CSI) is present in all storms studied with sting jets, while other rapidly developing storms of a similar character but no CSI do not develop sting jets. Therefore, it is assumed that the release of CSI is needed for sting jets to develop. While this instability will not be released in a physically realistic way in low‐resolution models (and hence sting jets are unlikely to occur), it is hypothesized that the signature of this instability (combined with other criteria that restrict analysis to moist mid‐tropospheric regions in the neighbourhood of a secondary cold front) can be used to identify cyclones in which sting jets occurred in reality. The diagnostic is evaluated, and appropriate parameter thresholds defined, by applying it to three case studies simulated using two resolutions (with CSI‐release resolved in only the higher‐resolution simulation). Copyright © 2011 Royal Meteorological Society and British Crown Copyright, the Met Office
A combination of in situ ESR and in situ NMR spectroelectrochemistry for mechanistic studies of electrode reactions: the case of p‐benzoquinone
Authors: Klod Sabrina , Dunsch Lothar
Published: October 2011

A combined in situ NMR and in situ ESR spectroelectrochemical study of a reaction mechanism is presented detecting and describing the whole number of paramagnetic and diamagnetic intermediates and final products in an electrode reaction. While in situ NMR spectroelectrochemistry provides a powerful method for the study of structural or electronic changes of diamagnetic molecules in any electrochemical reaction mechanism, in situ ESR spectroelectrochemistry is the method of choice to detect paramagnetic structures and to characterise their electronic state via the g‐value and hyperfine splitting in redox reactions. To demonstrate the power of this combination of magnetic spectroscopies in electrochemistry, the reduction of p‐benzoquinone to hydroquinone is followed by both these spectroelectrochemical methods at selected pH values, thus considering the influence of the proton on the reaction mechanism. The results of both in situ spectroelectrochemical methods at the same redox system are used to get the complete reaction mechanism of p‐benzoquinone at electrodes in aqueous solutions. Copyright © 2011 John Wiley & Sons, Ltd.
Mit Klick zu neuen Liganden
Authors: Schweinfurth David , Deibel Naina , Weisser Fritz , Sarkar Biprajit
Published: October 2011

Funktionelle Metallkomplexe mit substituierten 1,2,3‐Triazol liganden fanden in den letzten Jahren Anwendung in optoelektronischen Systemen, supramolekularen Verbindungen, magnetisch bistabilen Materialien, Metallionen‐Analytik und homogener Katalyse. Die wichtigste Ursache für diese Band breite ist der modulare synthetische Ansatz und die einfache Ligandenfunktionalisierung durch die Klick‐Reaktion.
Algen: Rohstoffe für Gesundheit, Schönheit und Energie
Authors: Griehl Carola , Bieler Simone
Published: October 2011

Algen sind einfach organisierte, schnell wachsende Wasserpflanzen. Als Phytoplankton oder Tange sind sie bedeutende nachwachsende Rohstoffe. Traditionell dienen Algen als Nahrungs‐ und Futtermittel oder Kosmetikbestandteil. Aktuell werden sie als alternative Energieträger erforscht.
Eltern und Kinder: Gemeinsam ins Labor
Authors: Sommer Katrin , Russek Adrian , Kleinhorst Helma
Published: October 2011

Eltern beeinflussen die Interessensbildung ihrer Kinder wesentlich — und zwar besonders stark bis zu einem Alter von zehn Jahren. Die Eltern müssen also in den Blickpunkt der Didaktiker rücken, wenn sich Kinder verstärkt für Naturwissenschaften begeistern und interessieren sollen.
Gibt es zu wenige Chemiker?
Authors: Osterath Brigitte
Published: October 2011

Alles spricht vom Fachkräftemangel. Existieren soll er auch bereits in der Chemie, munkeln einige. Doch wirklich eng wird es — wenn überhaupt — erst in frühestens fünf bis zehn Jahren.
An improved SPH method for saturated soils and its application to investigate the mechanisms of embankment failure: Case of hydrostatic pore‐water pressure
Authors: Bui Ha H. , Fukagawa Ryoichi
Published: October 2011

The method of smoothed particle hydrodynamics (SPH) has recently been applied to computational geomechanics and has been shown to be a powerful alternative to the standard numerical method, that is, the finite element method, for handling large deformation and post‐failure of geomaterials. However, very few studies apply the SPH method to model saturated or submerged soil problems. Our recent studies of this matter revealed that significant errors may be made if the gradient of the pore‐water pressure is handled using the standard SPH formulation. To overcome this problem and to enhance the SPH applications to computational geomechanics, this article proposes a general SPH formulation, which can be applied straightforwardly to dry and saturated soils. For simplicity, the current work assumes hydrostatic pore‐water pressure. It is shown that the proposed formulation can remove the numerical error mentioned earlier. Moreover, this formulation automatically satisfies the dynamic boundary conditions at a submerged ground surface, thereby saving computational cost. Discussions on the applications of the standard and new SPH formulations are also given through some numerical tests. Furthermore, techniques to obtain the correct SPH solution are also proposed and discussed throughout. As an application of the proposed method, the effect of the dilatancy angle on the failure mechanism of a two‐sided embankment subjected to a high groundwater table is presented and compared with that of other solutions. Finally, the proposed formulation can be considered a basic formulation for further developments of SPH for saturated soils. Copyright © 2011 John Wiley & Sons, Ltd.
A virtual experiment technique on the elementary behaviour of granular materials with discrete element method
Authors: Li Xia , Yu Hai‐Sui , Li Xiang‐Song
Published: October 2011

Multi‐scale investigations aided by the discrete element method (DEM) play a vital role for current state‐of‐the‐art research on the elementary behaviour of granular materials. Similar to laboratory tests, there are three important aspects to be considered carefully, which are the proper stress/strain definition and measurement, the application of target loading paths and the designed experiment setup, to be addressed in the present paper. Considering the volume sensitive characteristics of granular materials, in the proposed technique, the deformation of the tested specimen is controlled and measured by deformation gradient tensor involving both the undeformed configuration and the current configuration. Definitions of Biot strain and Cauchy stress are adopted. The expressions of them in terms of contact forces and particle displacements, respectively, are derived. The boundary of the tested specimen consists of rigid massless planar units. It is suggested that the representative element uses a convex polyhedral (polygonal) shape to minimize possible boundary arching effects. General loading paths are described by directly specifying the changes in the stress/strain invariants or directions. Loading can be applied in the strain‐controlled mode by specifying the translations and rotations of the boundary units, or in the stress‐controlled mode by using a servo‐control mechanism, or in the combination of the two methods to realize mixed boundary conditions. Taking the simulation results as the natural consequences originated from a complex system, virtual experiments provide particle‐scale information database to conduct multi‐scale investigations for better understanding in granular material behaviours and possible development of the constitutive theories provided the qualitative similarity between the simulation results from virtual experiments and observations on real material behaviour. Copyright © 2011 John Wiley & Sons, Ltd.
Induced fabric under cyclic and rotational loads in a strain space multiple mechanism model for granular materials
Authors: Iai Susumu , Tobita Tetsuo , Ozutsumi Osamu
Published: October 2011

The strain space multiple mechanism model idealizes the behavior of granular materials on the basis of a multitude of virtual simple shear mechanisms oriented in arbitrary directions. Within this modeling framework, the virtual simple shear stress is defined as a quantity dependent on the contact distribution function as well as the normal and tangential components of interparticle contact forces, which evolve independently during the loading process. In other terms, the virtual simple shear stress is an intermediate quantity in the upscaling process from the microscopic level (characterized by contact distribution and interparticle contact forces) to the macroscopic stress. The stress space fabric produces macroscopic stress through the tensorial average. Thus, the stress space fabric characterizes the fundamental and higher modes of anisotropy induced in granular materials. Herein, the induced fabric is associated with monotonic and cyclic loadings, loading with the rotation of the principal stress, and general loading. Upon loading with the rotation of the principal stress axis, some of the virtual simple shear mechanisms undergo loading whereas others undergo unloading. This process of fabric evolution is the primary cause of noncoaxiality between the axes of principal stresses and strains. Although cyclic behavior and behavior under the rotation of the principal stress axis seem to originate from two distinct mechanisms, the strain space multiple mechanism model demonstrates that these behaviors are closely related through the hysteretic damping factor. Copyright © 2011 John Wiley & Sons, Ltd.
Enhancement of properties of polyimide/silica hybrid nanocomposites by benzimidazole formed hydrogen bond
Authors: Zhang Peng , Chen Yi , Li Guoqiang , Luo Longbo , Pang Yuwei , Wang Xu , Peng Chaorong , Liu Xiangyang
Published: October 2011

Polyimide/silica hybrid nanocomposites were prepared by sol–gel method without coupling agent. A novel diamine with a benzimidazole group, 2‐(4‐aminophenyl)‐5‐aminobenzimidazole (PABZ), was introduced to copolymerize with 4,4'‐oxydianiline (ODA) and pyromellitic dianhydride (PMDA) to synthesize polyimide (PI) matrix. The compatibility between PI and silica was improved by hydrogen bonds formed between silica phase and the –NH– group on benzimidazole of the new diamine. Highly transparent hybrid films were obtained when silica content reached as high as 30 wt%. SEM results show that silica particles with sizes much smaller than that in PMDA‐ODA/silica system disperse homogeneously in the PI matrix. Differing from most hybrid systems without coupling agent, the tensile strength of PABZ system increases from 152 MPa to 165 MPa with silica content increasing from 0 to 20 wt%, while, it decreases linearly in PMDA‐ODA system. DMA analysis shows that the introduction of PABZ largely increases the glass transition temperature (Tg) for all silica contents, which is suggested to be due to the more rigid structures and stronger interaction between the two phases. Meanwhile, the decomposition temperature and char yields at 800 °C are both higher than that of pure PIs. The structures of the hybrid films were identified by FTIR spectra, which indicate that different silica morphologies are developed, resulted from the hydrogen bonds between benzimidazole and silica phase. Copyright © 2011 John Wiley & Sons, Ltd.
Improved micromorph solar cells by means of mixed‐phase n‐doped silicon oxide layers
Authors: Veneri Paola Delli , Mercaldo Lucia V. , Usatii Iurie
Published: October 2011

A good light trapping scheme is necessary to improve the performance of amorphous/microcrystalline silicon tandem cells. This is generally achieved by using a highly reflective transparent conducting oxide/metal back contact plus an intermediate reflector between the component cells. In this work, the use of doped silicon oxide as alternative n‐layer in micromorph solar cells is proposed as a means to obtain high current values using a simple Ag back contact and no extra reflector between the component cells n‐doped silicon oxide layers with a wide range of optical and electrical properties have been prepared. The influence of different deposition regimes on the material properties has been studied. The main findings are the following: (i) when carbon dioxide is added to the gas mixture, sufficiently high hydrogen dilution is necessary to widen the transition region from highly conductive microcrystalline‐like films to amorphous material characterized by low electrical conductivity; (ii) lower refractive index values are found with lower deposition pressure. Optimal n‐doped silicon oxide layers have been used in both component cells of micromorph devices, adopting a simple Ag back contact. Higher current values for both cells are obtained in comparison with the values obtained using standard n‐doped microcrystalline silicon, whereas similar values of fill factor and open circuit voltage are measured. The current enhancement is particularly evident for the bottom cell, as revealed by the increased spectral response in the red/infrared region. The results prove the high potential of n‐doped silicon oxide as ideal reflector for thin‐film silicon solar cells. Copyright © 2011 John Wiley & Sons, Ltd.
Hydroxyl Radical and Hydrogen Peroxide are Primarily Responsible for Dielectric Barrier Discharge Plasma‐Induced Angiogenesis
Authors: Priya Arjunan Krishna , Morss Clyne Alisa
Published: October 2011

Non‐thermal plasmas have recently been applied to biomedical challenges, including blood coagulation, sterilization and malignant cell apoptosis. We previously demonstrated that non‐thermal dielectric barrier discharge plasma promotes angiogenesis through reactive oxygen species‐induced fibroblast growth factor‐2 release. However, it remained unclear which plasma‐produced reactive species contributed to this effect. In this study, H2O2, OH•, O, and O2(1Δg) were measured in liquid and cells after plasma treatment using specific fluorescent probes. While all reactive species except O2(1Δg) increased with plasma dose in both liquid and cells, H2O2 and OH• were primarily responsible for plasma‐induced angiogenesis. This study will guide development of new plasma devices for angiogenesis in wound healing and tissue engineering.

magnified image
Observations of Hg0.7Cd0.3Te epilayers by infrared cathodoluminescence detection
Authors: Myhajlenko S. , Edwards J.L. , Rowley K.L. , Roedel R.J.
Published: October 2011

Extension in wavelength detection of cathodoluminescence (CL) toward the infrared is an area attracting interest regarding its development potential. This article describes our progress in CL characterization of Hg1−xCdxTe epilayers intended for optoelectronic array applications in the 3–5 μm radiation window. We present a description of the equipment set‐up, experimental procedure, and difficulties encountered in this study. We present preliminary observations performed at liquid helium temperatures of CL contrast variations from liquid phase epitaxial layers of Hg0.7Cd0.3Te lattice matched to Cd0.96Zn0.04Te substrates.
Phase transformation and dehydration of calcium sulphate dihydrate in solution studied by SEM
Authors: Sirota I. S. , Dorozhkin S. V. , Kruchinina M. V. , Melikhov I. V.
Published: October 2011

The transformation of separate crystals of CaSO4·2H2O (DH) into CaSO4·O.5H2O (HH) in an aqueous solution of H3PO4 and H2SO4 at 90–97°C was studied using a JSM‐35CF SEM. The source DH and acids were reagent or commercial (taken from the production of H3PO4 by a wet process). DH was allowed to convert into HH and periodic samples of the suspension were drawn, filtered, and investigated in the solid phase by SEM. It was shown that the dehydration of reagent DH specimens occurred through the recrystallization mechanism, whereas the transformation of commercial DH into HH was basically topochemical and developed by a relay race mechanism without any phase transformation front. The observed difference between commercial and reagent DH specimens may be explained by differences in their crystalline structure, initial particle size and by the presence of impurities in DH and acids. It is established that chemical impurities can change the mechanism of the phase transformation of the crystals DH into HH.
Atomic force microscope imaging of the plasma membrane Ca2+ ATPase reconstituted in phospholipids
Authors: Kasas S. , Hofmann R , Celio M. R. , Carafoli E.
Published: October 2011

The atomic force microscope (AFM) offers the possibility to obtain high‐resolution images of biological samples immersed in a liquid. This ability was exploited to image the erythrocyte plasma membrane Ca2+ ATPase reconstituted in asolectin liposomes. The liposomes prepared in the presence of the Ca2+ ATPase exhibited particles protruding from their flat surface, which were absent in control preparations, (i.e., in liposomes prepared in the absence of the ATPase). Incubation of the liposomes containing the pump with IgM type monoclonal antibodies raised against the Ca2+ ATPase induces a 3–5‐fold increase in the size of the protruding particles, demonstrating that the protruding object observed is the reconstituted Ca2+ ATPase.
Use of image analysis in mathematical characterization of orientation data
Authors: Muhunthan B. , Alwail T. A.
Published: October 2011

The mechanical behavior of particulate media is influenced to a great extent by their discrete nature. To date, however, few attempts have been made to quantitatively relate microfabric to the stress–strain characteristics of these media. Recent advances in image analysis have opened new avenues for the use of mathematical characterization of these materials in constitutive models. A technique for it is presented. A comprehensive description of geomaterials can be achieved via two measures: A scalar measure giving the mean value of a fabric descriptor, and a tensor measure giving its distribution in space. The technique is based on extension to the classical stereological principles for implementation in an image analyzer. Use of the technique is illustrated with observations of the microstructure of soils. The effect of fabric on the response of soils under one‐dimensional compression is quantified on the basis of the proposed characterization. The proposed technique may also prove useful in quantifying the microstructure of many other types of particulate materials and cellular arrangements.
Accuracy and cost comparison in medical testing using sequential testing strategies
Authors: Ahmed Anwar E. , McClish Donna K. , Schubert Christine M.
Published: October 2011

The practice of sequential testing is followed by the evaluation of accuracy, but not by the evaluation of cost. This paper focuses on three logic rules for combining two sequences of tests: believe the positive (BP), which diagnoses disease if any of two tests is positive, believe the negative (BN), which diagnoses disease if any of two tests is negative, and believe the extreme (BE), which diagnoses disease if the first test is positive or, after a first inconclusive test, a second test is positive for disease. Comparisons of these strategies are provided in terms of accuracy using false positive rate, sensitivity pairs that make up the maximum receiver operating characteristic curve, and cost of testing, defined as the proportion of subjects needing two tests to diagnose disease. A method to incorporate the cost of testing into the definition of the optimal operating point is also presented. The performance of the testing strategies is examined with respect to the ratio of standard deviations and the correlation between test results under the bivariate normal assumptions. Under all parameter settings, the maximum receiver operating characteristic curve of the BE strategy never performed worse than the BN and BP strategies; the BE strategy also had the lowest cost. The use of body mass index and plasma glucose concentration to diagnose diabetes in Pima Indians was presented as a real‐world application. The optimal operating points found by the BN and BE strategies produce lower false positive rate values than the BP strategy for these data. Copyright © 2011 John Wiley & Sons, Ltd.
Probing the Electromagnetic Field Distribution within a Metallic Nanodisk
Authors: Meneses‐Rodríguez David , Ferreiro‐Vila Elías , Prieto Patricia , Anguita José , González María U. , García‐Martín José M. , Cebollada Alfonso , García‐Martín Antonio , Armelles Gaspar
Published: October 2011

A Co nanolayer is used as a local probe to evaluate the vertical inhomogeneous distribution of the electromagnetic (EM) field within a resonant metallic nanodisk. Taking advantage of the direct relation between the magneto‐optical activity and the electromagnetic field intensity in the Co layer, it is shown that the nonuniform EM distribution within the nanodisk under plasmon resonant conditions has maximum values close to the upper and lower flat faces, and a minimum value in the middle.
Solution‐Based Synthesis and Design of Late Transition Metal Chalcogenide Materials for Oxygen Reduction Reaction (ORR)
Authors: Gao Min‐Rui , Jiang Jun , Yu Shu‐Hong
Published: October 2011

Late transition metal chalcogenide (LTMC) nanomaterials have been introduced as a promising Pt‐free oxygen reduction reaction (ORR) electrocatalysts because of their low cost, good ORR activity, high methanol tolerance, and facile synthesis. Herein, an overview on the design and synthesis of LTMC nanomaterials by solution‐based strategies is presented along with their ORR performances. Current solution‐based synthetic approaches towards LTMC nanomaterials include a hydrothermal/solvothermal approach, single‐source precursor approach, hot‐injection approach, template‐directed soft synthesis, and Kirkendall‐effect‐induced soft synthesis. Although the ORR activity and stability of LTMC nanomaterials are still far from what is needed for practical fuel‐cell applications, much enhanced electrocatalytic performance can be expected. Recent advances have emphasized that decorating the surface of the LTMC nanostructures with other functional nanoparticles can lead to much better ORR catalytic activity. It is believed that new synthesis approaches to LTMCs, modification techniques of LTMCs, and LTMCs with desirable morphology, size, composition, and structures are expected to be developed in the future to satisfy the requirements of commercial fuel cells.
Babel and SOAP applications of extensible compilers
Authors: Scowen R. S.
Published: October 2011

This paper describes a method of writing compilers which can easily be extended or altered. Two applications of the method are described; the first is a conventional programming language called Babel and the second is a program called SOAP which documents ALGOL 60 programs. Two important features have made extensions practicable; the compiler has a modular construction and was initially written in ALGOL 60.
A multi‐terminal benchmark
Authors: Holdsworth D. , Robinson G. W. , Wells M.
Published: October 2011

A basic premise of all benchmarks is that the pattern of system use does not change when moving work from one system to another. Measurements made on one multi‐terminal system are described and an attempt made to justify the resulting benchmark, which of necessity is changed in detail in order to run on the new system.
Two unusual methods for debugging system software
Authors: Rain Mark
Published: October 2011

This paper describes the Bug Farm, a generator of test cases for compilers, and the Bug Contest, an administrative technique for speeding the process of testing system software. The techniques achieve a high rate of bug detection while minimizing user revulsion at undebugged software.
PEDANT: A computerized support to program modularity under limited memory conditions
Authors: Mosedale T. W.
Published: October 2011

Experience with conventional methods of defining subroutines shows that analytical algorithms lose generality once programmed, and can only be applied in new circumstances after laborious reprogramming; one consequence of this is the disparate abundance of existing program‐packages for mathematical statistics.

Standard building‐blocks in modular form are therefore required, which are capable of embodying individual algorithms such that they can then be applied freely by a user unfamiliar with programming languages. This generalized approach presupposes the availability of a flexible switchboard for data between each building‐block. A system has been developed on this principle to facilitate the realization of composite technical calculations; it is based on a standard manner of supplying each conventionally programmed algorithm with data. The organization necessary for implementation in a typical batch operating‐system (Siemens DOS) is explained: This involves well‐defined data interfaces within each building‐block supported by standard software, which organizes the data transfer.
An analysis of the loop optimization scores in knuth's ‘empirical study of FORTRAN programs’
Authors: Hoaglin David C.
Published: October 2011

The optimization scores for Knuth's random sample of inner loops are analysed to provide a unified comparison of the five optimization levels. The techniques used are those of exploratory data analysis, and their role in the analysis is discussed. As a consequence of the analysis, five rough groups of programs with different optimization behaviour are identified and tentatively characterized.
Statistics for FORTRAN identifiers and scatter storage techniques
Authors: Lurié D. , Vandoni C.
Published: October 2011

Statistical data is presented on the distribution of FORTRAN identifiers as a function of length and initial character. The performance of two hash coding algorithms is tested with random probing on a pool of actual FORTRAN identifiers. A significant gain in performance is observed relative to the theoretical case of random keys, which reinforces the case for hash coding for symbol table construction in FORTRAN compilers.
Improving the efficiency of direct‐memory‐access output operations
Authors: Cohn Charles Erwin
Published: October 2011

The improvements in throughput expected from direct‐memory‐access channels are not realized with simple input/output routines. For output operations, the improvements can be realized through the provision of a separate data buffer area in memory that may be accessed by the peripheral while the primary buffer area is being manipulated by the program. The method may be extended to peripherals that require error checking after output.
Serious FORTRAN—Part 2
Authors: Larmouth J.
Published: October 2011

The second part of this paper addressed to those who write FORTRAN programs of more than transitory life deals with facilities outside the Standard, optimization, recursion, the design of user interfaces, debugging and program proving.
Aspects of reference locality in list structures in virtual memory
Authors: Baecker H. D.
Published: October 2011

Some aspects of the problem of achieving reference locality within a virtual memory organization during the processing of list structures are discussed. We also describe a limited series of experiments to explore different techniques for the representation and allocation of list structures in a virtual memory. The experimental results tend to show that there are cost advantages in separating the organizational skeleton of a list from the data being structured. However, these results apply only to the cost factors inherent in the use of current hardware and may be altered by technological advances.
The mistress user's book
Authors: Alcock Donald , Shearing Brian
Published: October 2011

The MISTRESS User's Book is reproduced here at our enthusiastic invitation. Inspired by it ourselves, we feel that it will be a far greater inspiration to writers than any number of dry articles on how to document software systems. It is introduced below by its authors.
The cambridge multiple‐access system in retrospect
Authors: Wilkes M. V.
Published: October 2011

This paper reports on some of the lessons that have been learned during 5 years' operation of the Cambridge Multiple‐Access System. It begins by summarizing the design goals and goes on to describe the way in which on‐line and off‐line facilities have been integrated. There is a section on security of access and one on the maintenance and up‐dating of the system. Scheduling of jobs is largely automatic and the operators receive their instructions from the system. Experience obtained in the operation of the system is discussed both from a software and a managerial point of view.