bluuebunny/crossref_metadata_2025 huggingface dataset:
Drying and processing protocols affect the quantification of cyanogenic glucosides in forage sorghum
Authors: Gleadow Roslyn M , Møldrup Morten E , O'Donnell Natalie H , Stuart Peter N
Published: June 2012

Background: Cyanogenic glucosides are common bioactive products that break down to release toxic hydrogen cyanide (HCN) when combined with specific β‐glucosidases. In forage sorghum, high concentrations of the cyanogenic glucoside dhurrin lead to reduced productivity and sometimes death of grazing animals, especially in times of drought, when the dhurrin content of stunted crops is often higher. The aim of this study was to develop harvesting protocols suitable for sampling in remote areas.

Results: Dhurrin concentration in air‐ and oven‐dried leaves was the same as in fresh leaves, with no subsequent losses during storage. Dhurrin concentration was halved when leaves were freeze‐dried, although activity of the endogenous dhurrinase was preserved. Direct measurement of dhurrin concentration in methanolic extracts using liquid chromatography/mass spectrometry (LC/MS) gave similar results to methods that captured evolved cyanide. A single freezing event was as effective as fine grinding in facilitating complete conversion of dhurrin to cyanide.

Conclusion: Direct measurement of dhurrin using LC/MS is accurate but expensive and not appropriate for fieldwork. Air drying provides an accurate, low‐cost method for preparing tissue for dhurrin analysis, so long as the specific β‐glucosidase is added. It is recommended that comparative studies like the one presented here be extended to other cyanogenic species. Copyright © 2012 Society of Chemical Industry
A Polyurethane Surface Modifier: Contrasting Amphiphilic and Contraphilic Surfaces Driven by Block and Random Soft Blocks Having Trifluoroethoxymethyl and PEG Side Chains
Authors: Zhang Wei , Fujiwara Tomoko , Taşkent Hűmeyra , Zheng Ying , Brunson Kennard , Gamble Lara , Wynne Kenneth J.
Published: June 2012

A conventional MDI‐BD‐PTMO polyurethane is modified using 2 wt% polyurethanes (U) having copolyoxetane soft blocks with hydrophobic 3F, CF3CH2OCH2— and hydrophilic MEn, CH3O(CH2CH2O)nCH2—, n = 3, 7) side chains. In contrast to neat 3F‐co‐MEn‐U, 2 wt% 3F‐co‐MEn‐U compositions have physically stable morphologies and wetting behavior. Surface composition (XPS) and amphiphilic or contraphilic wetting are controlled by the 3F‐co‐MEn polyoxetane soft block architecture and MEn side chain length. Importantly, θrec can be tuned for 2 wt% 3F‐co‐MEn‐U compositions independent of swelling, which is controlled by the bulk polyurethane. AFM imaging leads to a new morphological model whereby fluorous/PEG‐hard block nanoaggregates combine to form near surface features culminating in micron‐scale texturing.
Modification of Microbial Polymalic Acid With Hydrophobic Amino Acids for Drug‐Releasing Nanoparticles
Authors: Lanz‐Landázuri Alberto , García‐Alvarez Montserrat , Portilla‐Arias José , de Ilarduya Antxon Martínez , Holler Eggehard , Ljubimova Julia , Muñoz‐Guerra Sebastián
Published: June 2012

Microbial poly(β,L‐malic acid) was modified with either L‐leucine ethyl ester (L) or L‐phenylalanine methyl ester (F) to produce amphiphylic copolymers. The degradation of these copolymers in aqueous buffer took place under physiological conditions in a few weeks by hydrolysis of the side chain ester group followed by cleavage of the main chain. Spherical nanoparticles with diameters ranging between 70 and 230 nm were prepared from these copolymers by the dialysis‐precipitation method. No alteration of the cell viability was observed after incubation of these nanoparticles in different cell lines. Anticancer drugs temozolomide and doxorubicin were encapsulated in the nanoparticles. Temozolomide was released within several hours whereas doxorubicin took several weeks to be completely liberated.
Wetting Properties of Barium Sodium Niobate Filled Polystyrene Nanocomposite
Authors: Abraham Rosalin , Varughese K. T. , Isac Jayakumari , Thomas Sabu
Published: June 2012

Nano crystalline powders of Barium Sodium Niobate (BNN) with the composition (Ba3 Na4Nb10 O30) have been prepared by conventional ceramic technique. XRD and SEM studies revealed that its particle size is in the nanometer range. Composites were prepared by mixing powders of BNN with polystyrene at different volume fractions of the material. Melt mixing technique was carried out in brabender plasticoder at a rotor speed of 60 rpm for composite preparation. Surface energy characteristics of the composites are measured using contact angle measurements of the composites with water and methlene iodide. The solid surface free energy is calculated from harmonic mean equations. The results are quantitatively analyzed with Girifalco‐Good empirical model and provide unique insight into its properties. Various wettability parameters such as total solid surface free energy, work of adhesion, interfacial free energy and spreading coefficient are analyzed. The different parameters are calculated from the harmonic mean equation. The work of adhesion and interfacial free energy, spreading coefficient, and Girifalco‐Good's interaction parameter had changed with composition. The surface properties can be controlled for a given polymer‐surface pair by controlling the chemical structure, composition etc.
Interfacial Tension and Width of an Asymmetric Polymer Mixture
Authors: Adhikari Narayan P.
Published: June 2012

We have used continuous space rod‐bead model and an off‐lattice Monte Carlo technique to investigate interfacial properties between two incompatible polymers of different stiffnesses. We have estimated the interfacial tension as well as interfacial width of all the systems studied. Further, by studying the interfacial tension and/or interfacial width in the weak segregation limit one can estimate the critical value of temperature at which two different kinds of polymers mix. In the present work, we have estimated the critical value of temperature at which the polymers mix by studying the interfacial width in the weak segregation limit for the different systems containing the flexible and semi‐flexible polymers of different stiffnesses.
The Effect of Compatibilizer on the Properties of Impact Poly(propylene)‐Wood Composites
Authors: Basson Nicolaas Christiaan , van Reenen Albert
Published: June 2012

The effect of two compatibilizers, polypropylene graft maleic anhydride (PPgMA) and ethylene vinyl alcohol (EvOH), on the physical properties of wood polymer composites were studied. The composites were prepared with pine wood and two different impact polypropylene polymers, where the polymers varied according to ethylene content. These compatibilizers, when used together and pre‐reacted to create a joint compatiblizer of PPgMA and EvOH, significantly improved control over the repeatability of the physical properties tested, compared to when the compatibilizers were used individually. The impact values were slightly reduced, however the standard deviation of these values showed that the variation in the impact properties were significantly minimized when EvOH was also introduced. It appears that the joint compatiblizer provides better control over the hardness to impact balance of these composite materials and some of these physical properties were improved depending on the ratio between PPgMA and EvOH used, in the joint compatibilizer. Due to the difference in chemistry between PPgMA and EvOH, we expected PPgMA to interact more with the crystalline polypropylene matrix of the impact polymer and the EvOH with the amorphous, rubbery part and yield interesting results.
Solvodynamic Properties of Sodium Polystyrenesulfo‐nate in Methanol‐Water Mixed Solvent Media in Absence and in the Presence of a Salt Using Viscometric Method
Authors: Bhattarai Ajaya , Das Bijan
Published: June 2012

Linear extrapolation of the reduced viscosity values of uncharged polymer solutions as the concentration approaches zero constitutes the basis for the traditional method for the determination of the intrinsic viscosities of polymer solutions. While this method works well for uncharged polymer solutions, it fails completely for polyelectrolyte solutions especially in absence and also in presence of small amount of an added electrolyte. A very convenient method has recently been proposed by Wolf (Wolf, Macromol. Rapid Commun. 2007, 28, 164) to determine the intrinsic viscosities of polyelectrolyte solutions on the basis of the laws of phenomenological thermodynamics applied to the viscosity of polymer solutions. In spite of the success and the convenience of this method, this has so far been applied to a limited number of polyelectrolyte systems by the Wolf group alone (Wolf, Macromol. Rapid Commun. 2007, 28, 164; Eckelt et al., Macromolecules 2008, 41, 912; Badiger et al., Macromol. Chem. Phys. 2008, 209, 2087; Ghimici et al., J. Phys. Chem.B. 2009, 113, 8020). In order to improve the situation, we have measured the viscosities of an anionic polyelectrolyte, sodium polystyrenesulfonate, in methanol‐water mixed solvent media both in absence and in the presence of an electrolyte, sodium chloride. The results show that the experimental data fit well with the Wolf model and thus allow the calculation of intrinsic viscosities, which provide important insight about the dependence of the polyion conformation on solvent composition as well as on the concentration of the added electrolyte. This new evaluation method, thus, proves to be very useful to a better understanding of the rheological behaviour of the polyelectrolyte system investigated.
Tunneling Effect in Polythiophene
Authors: Kelkar Deepali , Chourasia Ashish , Balasubramanian Venkitarman
Published: June 2012

Polythiophene has been chemically synthesized using 2,5– dibromothiophene by debromination with magnesium, catalyzed by nickel chloride. The synthesized polymer was undoped using liquid ammonia and then doped again using 5% (wt/volume) aqueous FeCl3 for 2.5, 5 and 10 hour duration. Characterization of undoped as well as doped samples using elemental analysis and FTIR has been carried out. Elemental analysis shows that concentration of Fe+ atoms increases as the duration of doping increases. The FTIR spectrum reveals the complex formation between FeCl3 and polythiophene. All samples were pressed into pellets of about 1cm in diameter. The pellets were coated with gold (Au) on one side and with aluminum (Al) on other side using vacuum deposition technique. I–V measurements of undoped and FeCl3 doped samples, after coating have been carried out using two probe method. I–V measurements, at room temperature, were carried out by applying d. c. voltage with +ve potential to the side of the pellet coated with Au and –ve potential to Al from 0 V to 1 V in step of 0.01 V and then from 1V to 15 V in step of 0.5 V. The measurements were again carried out after interchanging the polarity of the applied voltage. These characteristics are just similar to the characteristics of conventional tunnel diode in forward bias condition and like Schottky diode in reverse bias condition. Various parameters of tunnel diode such as figure of merit, voltage spread, noise figure etc are calculated using the measurements carried out. Noise figure value of undoped polythiophene is very close to ideal value. The performance of all FeCl3 doped sample reduces, however value of the current ratio Ip/Iv (figure of merit) value for 5 hr. FeCl3 doped polythiophene sample matches with that of silicon (Si) tunnel diode.
Hierarchically Structured Materials for Bone Regeneration: Biomimetic Morphology, Micro‐Mechanics and Properties
Authors: Henning Sven , Imam Khasim H. R. , Michler Goerg H. , Brandt Jörg
Published: June 2012

The contribution describes the development of a biocompatible nanocomposite material consisting of a resorbable polymeric matrix and osteoinductive nanoparticles that can be used to manufacture compact products, porous scaffolds, hybrid nanofibers, and alternating porous/compact structures. It is shown that the material has a good balance of stiffness, strength and toughness. The material supports osteoblast proliferation. Based on a modular design principle, several prototypes for hierarchical 3D constructs are proposed.
Novel Hydrophobic Biodegradable Ester‐Polymers Obtained via Azlactone Chemistry
Authors: Kobauri Sophia , Zavaradshvili Nino , Dgebuadze Marina , Tugushi David , Katsarava Ramaz
Published: June 2012

Biodegradable polymers having a potential for constructing resorbable therapeutical micro‐ and nano‐containers were synthesized by interaction of bis‐azlactones with bis‐(L‐leucine)‐1,6‐hexylene diester/1,6‐diamino hexane either separately or as comonomers. The thermograms (DSC) all of them showed a wide endothermal peak within 55–120 °C with a maximum ranged from 86 °C to 96 °C. The peak was assigned to the melting of hydrophobic domains formed by aromatic terephthalic acid fragments in the polymeric backbones. Preliminary in vitro study showed that the ester‐bonds containing polymers obtained are biodegradable – α‐chymotrypsin catalyzed ester bonds hydrolysis rates ranged within 0.02–0.34 µmole/min.
Instrumented Macroindentation Techniques for Polymers and Composites – Mechanical Properties, Fracture Toughness and Time‐Dependent Behaviour as a Function of the Temperature
Authors: Lach Ralf , Schöne Jan , Bierögel Christian , Grellmann Wolfgang
Published: June 2012

An innovative cooling and heating device has been successfully applied to an instrumented macrohardness testing machine in close collaboration with the company Zwick/Roell. The prototype allows the local time‐dependent analysis of mechanical properties such as Martens hardness and indentation modulus, as well as fracture toughness and creep and relaxation behaviour at temperatures ranging from −100 °C to +100 °C. On the basis of load–indentation depth, load–time or indentation depth–time diagrams, the indentation behaviour as a function of test speed and/or temperature (which has rarely been done for polymers in the macro‐range of loading) depending on matrix and materials composition (amorphous/semicrystalline thermoplastics, epoxy resins, micro‐ and nanocomposites) has been analysed. Martens‐hardness, indentation modulus on the one hand and creep compliance and relaxation modulus on the other have been found to be strongly temperature dependent. Adequate methods of indentation fracture mechanics have been enhanced for polymers and applied to determine the fracture toughness of very different polymer‐based materials.
Microdeformation in Poly‐L‐lactide and Poly‐L‐lactide + Hydroxyapatite Nanocomposite Thin Films
Authors: Plummer Christopher J.G. , Choo Caleb K.C. , Delabarde Claire , Månson Jan‐Anders E.
Published: June 2012

In order to gain new insight into failure mechanisms in poly‐L‐lactide (PLLA) and PLLA + hydroxyapatite nanocomposites, transmission electron microscopy has been used to investigate room temperature microdeformation in electron transparent thin films of these materials subjected to various heat treatments and deformed in tension using the “copper grid” technique. In amorphous PLLA the dominant microdeformation mechanism was crazing. Localized fibrillar deformation zones (DZs) were also observed in semicrystalline films, tending to propagate in regions where the lamellar trajectories were at high angles to the tensile axis. Thus, in spherulitic films, in which the lamellae formed well‐defined stacks with approximately straight trajectories at the scale of the spherulite radii, individual DZs were observed to propagate over relatively large distances, as in the amorphous films. On the other hand, films cold crystallized by heating from the glassy state showed more homogeneous lamellar textures. These were associated with a relatively high density of low aspect ratio DZs. Addition of well dispersed nanosized hydroxyapatite (nHA) to the amorphous PLLA films was also found to result in an increase in the craze density, attributed to stress concentrations associated with void formation at the PLLA‐particle interfaces during deformation. However, interpretation was less straightforward in cold crystallized PLLA + nHA thin films, owing to a correlation between the lamellar texture and the nHA particles. In this case, both void formation and favorable lamellar orientations may have contributed to initiation of the DZs in the vicinity of the particles. The results are argued to be broadly consistent with previous observations of the behavior of bulk PLLA and PLLA + nHA films with a range of microstructures, in which there was evidence for an improvement in ductility in the presence of the nHA, again attributed to voiding at the PLLA‐particle interfaces.
The Effect of UV‐Irradiation on Poly(vinyl alcohol) Composites with Bacterial Cellulose
Authors: Stoica‐Guzun Anicuta , Stroescu Marta , Jipa Iuliana , Dobre Loredana , Jinga Sorin , Zaharescu Traian
Published: June 2012

The development of biodegradable packaging materials, especially from renewable resources is a constant preoccupation of nowadays, because of the environmental problems caused by synthetic polymers. The combination of cellulose with other polymeric materials could be an ecologic alternative and a way to use renewable resources for food packaging. Bacterial cellulose which is produced by microbial fermentation is also a promising material which can be used not only in biomedical application, but also as food packaging material. In this research different composite films between poly(vinyl alcohol)‐bacterial cellulose (PVA‐BC) were obtained by casting method. The obtained films were UV irradiated for different periods of times from 1 to 10 hours, using a mercury lamp, Philips TUV‐30, emitting light mainly at 254 nm. Changes in FT‐IR spectra before and after UV irradiation and the modification of transparency and of the swelling characteristics of the films were observed. As it was expected the composites materials are sensitive at UV exposure.
Improvement in Radiation Stability of EPDM by Efficient Antioxidants
Authors: Zaharescu Traian , Jipa Silviu , Henderson David
Published: June 2012

This paper analyses the stabilization effect induced by the presence of several compounds with antioxidant features (oleanolic acid, quercetin, capsaicin, metallic selenium and rosemary extract). The investigation are carried out for different additive concentrations (0, 0.25, 0.50 and 1% w/w), as well as for pairs of metallic selenium with the other four compounds. For antirad contribution to the delaying of radiochemical oxidation, modified and pristine EPDM samples were irradiated in GAMMATOR machinery provided with 137Cs source. While dose rate is 0.4 kGy.h−1, the total doses were 0, 10, 20 and 30 kGy, which are specific for radiosterilization. The results are obtained by application of two complementary techniques: isothermal chemiluminescence (180 °C) and FT‐IR spectroscopy. From chemiluminescence determinations oxidation induction times and rate of oxidation were calculated as the main kinetic characteristics depicting the progress in the oxidative degradation of polymer substrate. FT‐IR spectroscopy allows us to evaluate the evolution of hydroxyl and carbonyl accumulations.
Hierarchical Micro/Nanostructures of Natural Polymer for Release Process
Authors: Dluska Ewa , Markowska‐Radomska Agnieszka
Published: June 2012

In this paper the modeling of drug release process from hierarchical dispersed systems such as nano and microparticles prepared by thermal cross‐linking of multiple emulsions is described. The presented model considers the diffusion of a drug through spherical eroding natural polymer matrix and diffusion‐convection of the drug in the surrounding medium. Simulated release profiles were compared with experimental data of the drug release from microspheres of various structures. The differences in microspheres structure resulted from changes in mixing intensity of the external surrounding. The simulations of release profiles confirmed the importance of the internal structure of microspheres as well as an intensity of external mixing in the modeling of the controlled release process. The presented model allowed the mass of drug released to be determined with satisfactory agreement with experimental data after optimization of parameters describing internal microspheres structure. The proposed model describing release process of a drug from microspheres can be applied for simulation of release profiles with phasic behavior (primary/lag and continuous release). The model simulations were extended to drug release from nanoparticles with satisfactory results.
The distinct movement disorder in anti‐NMDA receptor encephalitis may be related to status dissociatus: A hypothesis
Authors: Stamelou Maria , Plazzi Giuseppe , Lugaresi Elio , Edwards Mark J. , Bhatia Kailash P.
Published: June 2012

The majority of patients with anti‐N‐methyl‐D‐aspartate‐receptor encephalitis (NMDAE) present a characteristic movement disorder, which consists of complex bilateral stereotyped movements of the arms, with perioral and eye movements, and less frequently involvement of the legs. We have observed striking similarities in the characteristics of the abnormal movements observed in NMDAE and those described in Status Dissociatus, which is characterized by a complete breakdown of state‐determining boundaries (wakefulness, REM and NREM sleep) and can result from pathophysiologically diverse disorders (e.g. fatal familial insomnia, delirium tremens, Morvan's syndrome). Here, we suggest that the state of paradoxical responsiveness in which NMDAE patients present these stereotyped movements may be that of Status Dissociatus and discuss the clinical similarities and pathophysiological explanations that support such a suggestion. This hypothesis explains why patients that seem to be unconscious have a movement disorder that is not epileptic and may have management implications, since many patients with NMDAE‐related movement disorder are treated with anticonvulsants that may not be indicated. © 2012 Movement Disorder Society
Enhanced low‐frequency oscillatory activity of the subthalamic nucleus in a patient with dystonia
Authors: Neumann Wolf‐Julian , Huebl Julius , Brücke Christof , Ruiz Maria Herrojo , Kupsch Andreas , Schneider Gerd‐Helge , Kühn Andrea A.
Published: June 2012

Background:

Local field potentials were recorded from the subthalamic nucleus (STN) in a patient with dystonia to further elucidate disease‐specific aspects of basal ganglia oscillatory activity.

Methods:

STN local field potentials and electromyograms (EMGs) from dystonic muscles were recorded to provide an estimate of the power spectra and coherence between the STN activity and EMG.

Results:

STN power spectra revealed a distinct peak at approximately 7 Hz in our patient. This finding is similar to the pallidal activity seen in dystonic patients but clearly different from the subthalamic beta activity of patients with Parkinson's disease. Significant coherence between STN activity and EMG was present in the 4‐ to 12‐Hz band in this patient.

Conclusions:

Dystonia is associated with pathological activity in the theta range present throughout the cortical‐basal ganglia network. This activity differs from that in Parkinson's disease, suggesting that different movement disorders may involve distinct oscillatory circuit disturbances. © 2012 Movement Disorder Society
On sensitive elliptic singular perturbation problems and logarithmic oscillations: the case of shells with edges
Authors: Merabet I. , Sanchez‐Palencia E.
Published: June 2012

This work deals with singular perturbation problems depending on small positive parameter ϵ. The limit problem as ϵ → 0 has no solution within the classical theory of PDEs, which uses distribution theory. A very particular and less‐known phenomenon appears: large oscillations. These problems exhibit some kind of instability; very small and smooth variations of the data imply large singular perturbations of the solution. That kind of problems appears in elasticity for highly compressible two‐dimensional bodies and thin shells with elliptic middle surface with a part of the boundary free. Here, we consider certain properties of that oscillations and extend the theory to shells with edges. Copyright © 2012 John Wiley & Sons, Ltd.
An efficient integration technique for the voxel‐based finite cell method
Authors: Yang Z. , Ruess M. , Kollmannsberger S. , Düster A. , Rank E.
Published: June 2012

The finite cell method is a fictitious domain approach based on hierarchical Ansatz spaces of higher order. The method avoids time‐consuming and often error‐prone mesh‐generation and favorably exploits Cartesian grids to embed structures of complex geometry in a simple‐shaped computational domain thus shifting parts of the computational effort from mesh generation to the computation within the embedding finite cells of regular shape. This paper presents an effective integration approach for voxel‐based models of linear elasticity that drastically reduces the computational effort on cell level. The applied strategy allows the pre‐computation of an essential part of the cell matrices and vectors of higher order, representing stiffness and load, respectively. Several benchmark problems show the potential of the proposed method in particular for heterogeneous material properties as common in biomedical applications based on computer tomography scans. The applied strategy ensures a fast computation for time‐critical simulations and even allows user‐interactive simulations for models of moderate size at a high level of accuracy. Copyright © 2012 John Wiley & Sons, Ltd.
The enhanced assumed strain method for the isogeometric analysis of nearly incompressible deformation of solids
Authors: Cardoso Rui P. R. , Cesar de Sa J. M. A.
Published: June 2012

Isogeometric analysis has recently become very popular for the numerical modeling of structures and fluids. Among other potential features, advantages of using a non‐uniform rational B‐splines (NURBS)‐based isogeometric analysis over the traditional finite element method include the possibility of using higher‐order polynomials for the basis functions of the approximation space, which may be easily built on a recursive (hierarchical) fashion as well as higher convergence ratio. Nevertheless, NURBS‐based isogeometric analysis suffers from the same problems depicted by other methods when it comes to reproduce isochoric deformations, that is, it shows volumetric locking, especially for low‐order basis functions. Similar remedies as those that have been proposed for the finite element method may be appropriate for integration in the NURBS‐based isogeometric analysis and some have already been tried with success. In this work, the analysis of the underlying space of incompressible deformations of a NURBS‐based isogeometric approximation is performed with the main objective of understanding the likelihood of volumetric locking. As a remedy, the enhanced assumed strain methodology is blended with the NURBS‐based isogeometric analysis to alleviate the volumetric locking associated with incompressible deformations. The solution includes a stabilization term derived directly from a penalized form of the classical Veubeke–Hu–Washizu three‐field variational principle. Copyright © 2012 John Wiley & Sons, Ltd.
Modified resistivity–strain behavior through the incorporation of metallic particles in conductive polymer composite fibers containing carbon nanotubes
Authors: Lin Li , Deng Hua , Gao Xiang , Zhang Shuangmei , Bilotti Emiliano , Peijs Ton , Fu Qiang
Published: June 2012

Eutectic metal particles and carbon nanotubes are incorporated into a thermoplastic polyurethane matrix through a simple but efficient method, melt compounding, to tune the resistivity–strain behavior of conductive polymer composite (CPC) fibers. Such a combination of conductive fillers is rarely used for CPCs in the literature. To characterize the strain‐sensing properties of these fibers, both linear and dynamic strain loadings are carried out. It is noted that a higher metal content in the fibers results in higher strain sensitivity. These strain‐sensing results are discussed through a morphological study combined with a model based on the classic tunneling model of Simmons. It is suggested that a high tunneling barrier height is preferred in order to achieve higher strain sensitivity. Copyright © 2012 Society of Chemical Industry
Geometrical optimization and contact configuration in radial pn junction silicon nanorod and microrod solar cells
Authors: Voigt F. , Stelzner T. , Christiansen S.
Published: June 2012

Electric charge transport simulations of symmetrically doped radial pn junction silicon nanorod solar cells were performed using the Technology Computer‐aided Design software suite by Silvaco. Two schemes of electric contacting were applied, the first one consisting of a cathode wrapped around the cladding of the rod and the second one in a cathode located only on the top rod surface. In both cases, the anode was implemented just below the bottom end of the p‐type rod core. P‐type cores and n‐type shells of the rods were assumed, with dopant densities of 1018 cm− 3 in both regions. The location of the pn junction was chosen such that well‐formed space charge regions could be established with the outer end of the n‐type depletion region being adjacent to the cylindric surface of the nanorod. Rod radii and rod lengths were varied and optimized in a three‐step process for both types of contacting schemes. It was found that inhomogeneous carrier generation profiles diminish the open‐circuit voltage in case of a wrapped cathode configuration. Most realistic is the usage of a top contact configuration with rod radii of 2 µm and lengths of around 100 µm, leading to a cell efficiency of about 15%. Further enhancement of performance is expected, if light trapping of the nanorod layer is taken into account and photonic light harvesting is applied. Copyright © 2012 John Wiley & Sons, Ltd.
CdTe/CdS thin film solar cells grown in substrate configuration
Authors: Gretener Christina , Perrenoud Julian , Kranz Lukas , Kneer Luisa , Schmitt Rafael , Buecheler Stephan , Tiwari Ayodhya N.
Published: June 2012

The ability to grow efficient CdTe/CdS solar cells in substrate configuration would not only allow for the use of non‐transparent and flexible substrates but also enable a better control of junction formation. Yet, the problems of barrier formation at the back contact as well as the formation of a p–n junction with reduced recombination losses have to be solved. In this work, CdTe/CdS solar cells in substrate configuration were developed, and the results on different combinations of back contact materials are presented. The Cu content in the electrical back contact was found to be a crucial parameter for the optimal CdCl2‐treatment procedure. For Cu‐free cells, two activation treatments were applied, whereas Cu‐containing cells were only treated once after the CdTe deposition. A recrystallization behavior of the CdTe layer upon its activation similar to superstrate configuration was found; however, no CdTe–CdS intermixing could be observed when the layers were treated consecutively. Remarkably high VOC and fill factor of 768 mV and 68.6%, respectively, were achieved using a combination of MoO3, Te, and Cu as back contact buffer layer resulting in 11.3% conversion efficiency. With a Cu‐free MoO3/Te buffer material, a VOC of 733 mV, a fill factor of 62.3%, and an efficiency of 10.0% were obtained. Copyright © 2012 John Wiley & Sons, Ltd.
Accurate explicit equations for the fill factor of real solar cells—Applications to thin‐film solar cells
Authors: Taretto K. , Soldera M. , Troviano M.
Published: June 2012

Even within the simplest real solar cell model, the exact value of the fill factor (FF) is only computable by numerical calculations. Here, we perform approximations to the power–voltage curve given by the one‐diode model with series and shunt resistance losses, obtaining explicit expressions for the voltage and current at the maximum power point, and thus an explicit approach for the FF. Over a broad range of possible solar cell parameters, including cells where the impact of shunt losses on the fill factor is not negligible, the approximate equations yield relative errors typically around 1%. The equations are applied to explore the dependence of FF on alternative buffer material thickness of organic solar cells, and to investigate the incidence of shunt and series resistance losses on the FF of Cu(In,Ga)Se2 solar cells under indoor illumination conditions. Copyright © 2012 John Wiley & Sons, Ltd.
A Complex quest: The development and research of underachievement interventions for gifted students
Authors: Rubenstein Lisa Davia , Siegle Del , REIS Sally M. , Mccoach D. Betsy , Burton Meredith Greene
Published: June 2012

The seeming lack of motivation of many academically gifted students is an area of frustration and concern for many parents, teachers, and psychologists. This article explores two studies in which researchers designed interventions to improve academic achievement. Both interventions were created using the Achievement‐Orientation Model. The first study matched the intervention to the student and found that the students' grades increased over the intervention period,t(45) = 2.56,p= .014,d= .38. Students using treatments linked to goal valuation and environmental perceptions showed the greatest academic grade growth; the self‐efficacy and self‐regulation groups showed little or no grade improvement. Building on the finding that goal valuation was important, the second study used a mixed‐methods design to pilot an intervention focused on goal valuation and student autonomy. The results of this study were mixed, as the intervention appeared to help two of the three students. Although these studies offer further insight into possibilities for promoting academic achievement among gifted students, further research examining how to best support and foster academic achievement in underachieving gifted students is needed. © 2012 Wiley Periodicals, Inc.
Suicide ideation and attempts among inpatient adolescents with borderline personality disorder: Frequency, intensity and age of onset
Authors: Venta Amanda , Ross Elizabeth , Schatte Dawnelle , Sharp Carla
Published: June 2012

Suicide ideation and attempts are a major health concern among adolescents, and recently, evidence has emerged suggesting that borderline personality disorder (BPD) may put individuals at even greater risk than depression alone. This is not surprising given that within adult samples, 8–10% of those diagnosed with BPD commit suicide. However, only a handful of studies have assessed the relation between BPD and suicide attempts among adolescents, and currently, nothing is known about the characteristics of suicide ideation among adolescents with BPD. Against this background, the aim of the present study was to examine the relation between BPD and the characteristics of suicide ideation and attempts (frequency, intensity and age of onset) in N = 106 adolescent inpatients. This question was examined using both clinician‐rated and adolescent‐rated measures of suicide ideation and attempts and both dimensional and categorical measures of BPD. The results of the present study indicate that adolescents with BPD experience suicide ideation earlier in life and more frequently than psychiatric controls. Notably, the groups did not differ with regard to adolescent‐rated intensity of suicide ideation nor frequency, intent to die or age of onset of suicide attempts. A number of possible explanations for the absence of these group differences are presented. Copyright © 2012 John Wiley & Sons, Ltd.
Synaptic proteome changes in mouse brain regions upon auditory discrimination learning
Authors: Kähne Thilo , Kolodziej Angela , Smalla Karl‐Heinz , Eisenschmidt Elke , Haus Utz‐Uwe , Weismantel Robert , Kropf Siegfried , Wetzel Wolfram , Ohl Frank W. , Tischmeyer Wolfgang , Naumann Michael , Gundelfinger Eckart D.
Published: June 2012

Changes in synaptic efficacy underlying learning and memory processes are assumed to be associated with alterations of the protein composition of synapses. Here, we performed a quantitative proteomic screen to monitor changes in the synaptic proteome of four brain areas (auditory cortex, frontal cortex, hippocampus striatum) during auditory learning. Mice were trained in a shuttle box GO/NO‐GO paradigm to discriminate between rising and falling frequency modulated tones to avoid mild electric foot shock. Control‐treated mice received corresponding numbers of either the tones or the foot shocks. Six hours and 24 h later, the composition of a fraction enriched in synaptic cytomatrix‐associated proteins was compared to that obtained from naïve mice by quantitative mass spectrometry. In the synaptic protein fraction obtained from trained mice, the average percentage (±SEM) of downregulated proteins (59.9 ± 0.5%) exceeded that of upregulated proteins (23.5 ± 0.8%) in the brain regions studied. This effect was significantly smaller in foot shock (42.7 ± 0.6% down, 40.7 ± 1.0% up) and tone controls (43.9 ± 1.0% down, 39.7 ± 0.9% up). These data suggest that learning processes initially induce removal and/or degradation of proteins from presynaptic and postsynaptic cytoskeletal matrices before these structures can acquire a new, postlearning organisation. In silico analysis points to a general role of insulin‐like signalling in this process.
Reverse DC bias stress shifts in organic thin‐film transistors with gate dielectrics using parylene‐C
Authors: Fukuda Kenjiro , Suzuki Tatsuya , Kumaki Daisuke , Tokito Shizuo
Published: June 2012

We have systematically investigated the reliability of organic thin‐film transistors (TFTs) using polychloro‐p‐xylylene (parylene‐C) as a gate dielectric material. The fabricated organic TFT devices exhibited positive bias shifts with negative DC gate‐source voltages; however, no hysteresis was observed in the transfer characteristics for the tested TFT devices. Moreover, this tendency was enhanced with increasing annealing temperatures, whereby X‐ray diffraction (XRD) results revealed that the crystallinity of the parylene‐C layers increased with thermal annealing. As a result the total dipole moments normal to the surface of the parylene‐C layers grew, which caused reverse bias shifts in the TFT devices.
Beyond the thermal set point: Significance of the compensatory temperatures of water vapor condensation in biological interactions
Authors: Chun Paul W.
Published: June 2012

This communication reports for the first time a link that has gone unrecognized between the compensatory temperatures of water vapor condensation and the thermal set point in interacting biological systems, where the bound unavailable energy TΔS° = 0, that is ΔH°(TS)(−) and ΔG°(TS)(−)min intersect. In addition to determining the unique thermal set point for water vapor, which falls at 260 K, our results indicate that in any biological interaction, the thermal set point must fall between the limits defined by the compensatory temperatures of water vapor, that is between 30 and 380 K, where ΔH°(Th)(+) ≅ TΔS°(Th)(+) at (Th) and ΔH°(Tm)(−) ≅ TΔS°(Tm)(−) at (Tm) or (Tcond). Only between these limits, where ΔG°(T) = 0, is the net chemical driving force favorable for biological interaction to occur. © 2012 Wiley Periodicals, Inc.
Persistence of Epoxy‐Based Sealer Residues in Dentin Treated With Different Chemical Removal Protocols
Authors: Kuga Milton Carlos , Faria Gisele , Rossi Marcos Antonio , do Carmo Monteiro Jardel Camilo , Bonetti‐Filho Idomeo , Berbert Fábio Luiz Camargo Vilella , Keine Kátia Cristina , Só Marcus Vinicius Reis
Published: June 2012

The presence of residual endodontic sealer in the pulp chamber may cause discoloration of the dental crown and interfere with the adhesion of restorative materials. The aim of this study was to compare the efficacy of different solvents in removing residues of an epoxy resin‐based sealer (AH Plus) from the dentin walls of the pulp chamber, by scanning electron microscopy (SEM). Forty‐four bovine incisor dental crown fragments were treated with 17% EDTA and 2.5% NaOCl. Specimens received a coating of AH Plus and were left undisturbed for 5 min. Then, specimens were divided in four groups (n = 10) and cleaned with one of the following solutions: isopropyl alcohol, 95% ethanol, acetone solution, or amyl acetate solution. Negative controls (n = 2) did not receive AH Plus, while in positive controls (n = 2) the sealer was not removed. AH Plus removal was evaluated by SEM, and a score system was applied. Data were analyzed by Kruskal–Wallis and Dunn tests. None of the solutions tested was able to completely remove AH Plus from the dentin of the pulp chamber. Amyl acetate performed better than 95% ethanol and isopropyl alcohol (p < 0.05), but not better than acetone (p > 0.05) in removing the sealer from dentin. No significant differences were observed between acetone, 95% ethanol, and isopropyl alcohol (p > 0.05). It was concluded that amyl acetate and acetone may be good options for cleaning the pulp chamber after obturation with AH Plus. SCANNING 35:17‐21, 2013. © 2012 Wiley Periodicals, Inc.
Mass spectrometry imaging of freeze‐dried membrane phospholipids of dividing Tetrahymena pyriformis
Authors: Lanekoff Ingela , Phan Nhu TN. , Van Bell Craig T. , Winograd Nicholas , Sjövall Peter , Ewing Andrew G.
Published: June 2012

Time of Flight secondary ion mass spectrometry (TOF‐SIMS) has been used to explore the distribution of phospholipids in the plasma membrane of Tetrahymena pyriformis during cell division. The dividing cells were freeze‐dried prior to analysis followed by line scan and region of interest analysis at various stages of cell division. The results showed no signs of phospholipid domain formation at the junction between the dividing cells. Instead the results showed that the sample preparation technique had a great impact on one of the examined phospholipids, namely phosphatidylcholine (PC). Phosphatidylcholine and 2‐aminoethylphosphonolipid (2‐AEP) have therefore been evaluated in Tetrahymena cells that have been subjected to different sample preparation techniques: freeze drying ex situ, freeze fracture, and freeze fracture with partial or total freeze drying in situ. The result suggests that freeze drying ex situ causes the celia to collapse and cover the plasma membrane. Copyright © 2012 John Wiley & Sons, Ltd.
SIMS analysis of the interaction between plasmas and the graphite first wall in RFX‐mod
Authors: Fiameni Stefania , Barison Simona , Canton Alessandra , Bello Samuele Dal , Innocente Paolo , Pagura Cesare , Fabrizio Monica , Daolio Sergio
Published: June 2012

Modified Reversed‐Field eXperiment is an experiment of magnetic confinement of thermonuclear plasma in the Reversed‐Field Pinch configuration. The toroidal device is designed to operate with hydrogen plasmas, and the most internal wall is entirely covered with polycrystalline graphite tiles. The disadvantage of graphite walls is the progressive hydrogen accumulation in graphite during operation. To overcome this problem, some graphite conditioning procedures are necessary (e.g. boronization, lithization and glow discharge). The critical role of graphite walls on plasma control suggested the use of secondary ion mass spectrometry (SIMS) technique for the evaluation of conditioning procedures efficacy. SIMS analyses of graphite samples after their exposure to plasmas or wall conditioning treatments are presented in this work. The SIMS technique resulted fundamental on the investigation of the boron distribution in the graphite tiles, and sample comparisons indicated the need for glow discharge cleaning system upgrading to improve the conditioning process and boronization uniformity. Copyright © 2012 John Wiley & Sons, Ltd.
Authenticity and TV Shows: A Multidimensional Analysis Perspective
Authors: Al‐Surmi Mansoor
Published: June 2012

Television shows, especially soap operas and sitcoms, are usually considered by English as a second language practitioners as a source of authentic spoken conversational materials presumably because they reflect the linguistic features of natural conversation. However, practitioners are faced with the dilemma of how to assess whether such conversational materials reflect the linguistic characteristics of natural ones. Previous classifications were based on practitioners' personal impressions and intuitions. The present study shows that this subjective approach is problematic and instead adopts a corpus‐based register analysis tool to investigate the extent to which soap opera, compared to sitcom, reflects the linguistic representation of natural conversation. The tool is the multidimensional analysis developed by Biber (1988). Findings indicate that sitcom captures the linguistic features of natural conversation more than soap opera does. Implications for research, teaching, and teaching materials development are discussed.
Engineered viral nanoparticles for flow cytometry and fluorescence microscopy applications
Authors: Robertson Kelly L. , Liu Jinny L.
Published: June 2012

Viral nanoparticles (VNPs) are attractive platforms for use in the biotechnology and biomedical fields because of their biological nature. A wide variety of these particles, labeled with fluorescent reporters, have been characterized using flow cytometry and cellular imaging techniques. Fluorescence microscopy allows the direct observation of VNPs on the cell surface or inside the membrane as well as the cellular localization of the nanoparticles while flow cytometry allows the statistical quantification of nanoparticle uptake and targeting specificity. These techniques are essential when characterizing the properties of VNPs and provide information toward the use of VNPs for targeting, imaging, and/or cargo delivery. WIREs Nanomed Nanobiotechnol 2012, 4:511–524. doi: 10.1002/wnan.1177

This article is categorized under:

Diagnostic Tools > Diagnostic Nanodevices

Diagnostic Tools > In Vitro Nanoparticle-Based Sensing

Nanotechnology Approaches to Biology > Nanoscale Systems in Biology
A Global Perspective of the Variables Associated with Acceptance of Evolution
Authors: Heddy Benjamin C. , Nadelson Louis S.
Published: June 2012

The controversy of biological evolution due to conflicts with personal beliefs and worldviews is a phenomenon that spans many cultures. Acceptance of evolution is essential for global advancement in science, technology, and agriculture. Previous research has tended to focus on the factors that can influence acceptance of evolution by culture or country. Our research explored the relationship on an international scale using secondary data analysis to research evolution acceptance for 35 countries. Our results indicate significant relationships between public acceptance of evolution and religiosity, school-life expectancy, science literacy, and gross domestic product per capita. Implications and future directions for research are addressed.