bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of Pertraction in Biotechnology
Authors: Caşcaval Dan , Galaction Anca‐Irina , Boldureanu Daniel
Published: October 2013

Pertraction, also defined as the extraction and transport through liquid membranes, consists in the transfer of a solute between two aqueous phases of different pH values or other chemical properties, phases that are separated by a solvent layer of various sizes. Pertraction efficiency and selectivity can be significantly enhanced by adding one or more carriers, such as organophosphoric compounds, long‐chain amines, or crown ethers, into the liquid membrane, the separation process being calledfacilitatedorsynergic pertraction.

Compared to the physical or reactive liquid‐liquid extraction, the pertraction method reduces the loss of solvent during the separation cycle, needs small quantity of solvent and carrier due to their continuous regeneration, and offers the possibility of solute transport against its concentration gradient as long as the pH gradient between the two aqueous phases is maintained.

In this context, this article overviews representative applications of pertraction for separating individually or selectively the biosynthetic products of carboxylic acids, amino acids, antibiotics, and vitamins. The main influences of the operating parameters on pertraction efficiency, the optimum separation conditions, and the models describing the behavior of pertraction systems are discussed in direct correlation with the practical potential of this separation technique for biotechnology.
Organic Solvent Nanofiltration
Authors: Székely György , Marchetti Patrizia , Jimenez‐Solomon Maria F. , Livingston Andrew G.
Published: October 2013

Organic solvent nanofiltration (OSN) is a pressure‐driven membrane process discriminating molecules in the range of 200‐1000 Da, providing high quality products through gentle operating conditions. OSN has significant potential in chemical‐related industries employing organic solvents including ionic liquids. The main advantages of OSN technologies include low energy consumption, operation time, and process complexity as well as improved production sustainability, quality, and yield. The article seeks to provide insight into the state‐of‐the‐art research in the field, including the development of new polymeric and ceramic OSN membranes, modeling studies of the transport mechanisms through OSN membranes, engineering of membrane modules, development of new membrane characterization techniques, and novel OSN application.
Food Industry Applications
Authors: Lipnizki Frank , Dupuy Aurélie
Published: October 2013

This article provides an overview on established membrane applications in the food industry and focuses on applications of membrane processes in the production of beer, wine, fruit juice, food additives, and dairy products such as milk, whey, and cheese. Furthermore, as the food industry is a highly water consuming industry one section of this article is dedicated to water preparation and wastewater treatment with membranes. The concluding sections will provide an outlook on the future of membrane technologies in the food industry.
Gold Nanotube Membranes
Authors: Velleman Leonora , Shapter Joe G. , Losic Dusan
Published: October 2013

In this review, we discuss gold nanotube membranes, which are of interest in the field of membrane separations. The review briefly describes the template synthesis approach based on electroless gold deposition for production of these membranes using polymer track‐etched and porous alumina membranes as a template. Separation using gold nanotube membranes based on strategies such as molecular size exclusion, charge, and molecular recognition are also presented. Gold nanotube membranes can perform various separations of ions, organic molecules, proteins, and nucleic acid. This review covers the concepts underlying the separation mechanisms as well as representative applications of gold nanotube membranes in biosensing, catalysis, and biomedical applications. The review concludes with an outlook providing a perspective for further developments and applications of gold nanotube membranes.
Membrane Bioreactors, Applications to Wastewater Treatment and Reuse
Authors: Krause Stefan , Thiemig Christoph
Published: October 2013

Membrane bioreactor (MBR) technology for wastewater treatment has attracted enormous attention worldwide over the past 15 years. MBRs combine biological wastewater treatment with membrane technology. Ultra‐ or microfiltration membranes separate the biomass from the mixed liquor during the activated sludge process (ASP). Herein, the membrane is employed as a filter and rejects the solids to provide a clarified product. The main advantages of the process are the superior effluent quality as a result of complete solid removal and the small footprint of the plant due to more compact aeration tanks and the absence of a final sedimentation tank. The disadvantages can be the membrane fouling and the higher energy demand of the process. Worldwide, MBR systems have been implemented in more than 200 countries. Key drivers for this technology are the legislation relating to environmental protection and wastewater management, local water scarcity, the cost (return on investment), and the increase in the acceptance of MBR technology and wastewater reuse.

To optimize the MBR process, the design of the conventional ASP needs to be modified at several points. The mechanical pretreatment, particularly the screening process, has to be adapted as classical screens of around 6 mm rating are insufficient for an MBR. Most MBRs are operated with 1 mm up to 3 mm screen gap size. The biological stage can be operated with higher mixed liquor suspended solids (MLSS) concentration. The content can be increased from about 3000 mg/l in conventional ASP to about 12,000 mg/l in MBR systems resulting in a lower foot print and lower hydraulic retention time (HRT). Also, the control of the MBR plant is more complex in comparison with conventional ASP as the membrane process must be embedded into the control system. In addition, the cleaning of the membrane must be implemented into design, operation, and control.
Membrane Related Conferences, Seminars, Symposia and Workshops
Authors: Tummons Emily N. , Herrera‐Robledo Miguel
Published: October 2013

This list of conferences, seminars, symposia, and workshops may not be completely exhaustive, but the major conferences, seminars, symposia, and workshops that focus on synthetic membranes and membrane processes are accounted for.
Single‐incision and NOTES Cholecystectomy, Are There Clinical or Cosmetic Advantages When Compared to Conventional Laparoscopic Cholecystectomy? A Case–control Study Comparing Single‐incision, Transvaginal, and Conventional Laparoscopic Technique for Cholecystectomy
Authors: van den Boezem Peter B. , Velthuis Simone , Lourens Harm J. , Cuesta Miguel A. , Sietses Colin
Published: October 2013

Background

The aim of the present study was to compare the clinical and cosmetic results of transvaginal hybrid cholecystectomy (TVC), single‐port cholecystectomy (SPC), and conventional laparoscopic cholecystectomy (CLC). Recently, single‐incision laparoscopic surgery and natural orifice transluminal endoscopic surgery have been developed as minimally invasive alternatives for CLC. Few comparative studies have been reported.

Methods

Female patients with symptomatic gallstone disease who were treated in 2011 with SPC, TVC, or CLC were entered into a database. Patients were matched for age, body mass index, and previous abdominal surgery. After the operation all patients received a survey with questions about recovery, cosmesis, and body image.

Results

A total of 90 patients, 30 in each group, were evaluated. Median operative time for CLC was significantly shorter (p < 0.001). There were no major complications. Length of hospital stay, postoperative pain, and postoperative complications were not significantly different. The results for cosmesis and body image after the transvaginal approach were significantly higher. None of the sexually active women observed postoperative dyspareunia.

Conclusions

Both SPC and TVC are feasible procedures when performed in selected patients. CLC is a faster procedure, but other clinical outcomes and complication rates were similar. SPC, and especially TVC, offer a better cosmetic result. Randomized trials are needed to specify the role of SPC and TVC in the treatment of patients with symptomatic gallstone disease.
The Use of Short Segment Free Jejunal Transfer as Salvage Surgery for Cervical Esophageal and Hypopharyngeal Cancer
Authors: Mayanagi Shuhei , Onitsuka Tetsuro , Nakagawa Masahiro , Sato Hiroshi , Kitagawa Yuko , Tsubosa Yasuhiro
Published: October 2013

Background

Salvage surgery after definitive chemoradiotherapy for cervical esophageal cancer and hypopharyngeal cancer remains a challenge because of the high rate of complications. The purpose of this study was to evaluate the safety and efficacy of free jejunal transfer as salvage surgery for cervical esophageal cancer and hypopharyngeal cancer after definitive chemoradiotherapy.

Methods

We enrolled eight patients with cervical esophageal cancer and 11 patients with hypopharyngeal cancer who underwent free jejunal transfer as salvage surgery following radiotherapy or chemoradiotherapy. In this study, we reviewed the surgical procedures, perioperative complications, and survival rates.

Results

The median duration of surgery was 514 min, and the median blood loss was 439 ml. In surgical procedures, the recipient vessels for the anastomosis of the free jejunum consisted of one artery and one vein (63 %), one artery and two veins (5 %), and two arteries and two veins (31 %). The postoperative morbidity rate was 57.9 % (11 patients), with six cases of partial necrosis of the tracheal margin and no cases of graft necrosis or postoperative in‐hospital death. The overall 5‐year survival rate after surgery was 58.1 %.

Conclusions

Our findings suggest that with careful attention to the potential development of necrosis of the tracheal margin, pharyngolaryngoesophagectomy and free jejunal transfer can be safely performed, even in patients who received radiotherapy or chemoradiotherapy.
Inferior Right Hepatic Vein‐preserving Major Right Hepatectomy for Hepatocellular Carcinoma in Patients with Significant Fibrosis or Cirrhosis
Authors: Jiang Chunping , Wang Zhongxia , Xu Qingxiang , Wu Xingyu , Ding Yitao
Published: October 2013

Background

Liver resection represents a most effective treatment for hepatocellular carcinoma (HCC). The extent of hepatectomy for HCC involves maintaining a tricky balance between radical resection of tumors and preservation of sufficient liver parenchyma. Generally, removal of the right hepatic vein often involves resection of the whole posterior right lobe, which may prevent patients with impaired liver function from maintaining a functional reserve and could also limit the future liver remnant from curative hepatectomy. As a common anatomic variation, preservation of the inferior right hepatic vein (IRHV) may enable preservation of liver segment 6, even when the right hepatic vein has to be removed. In the present study, we report our experience with IRHV‐preserving major right hepatectomy.

Methods

From February 2009 to December 2011, eight trisegmentectomies 5‐7‐8 and two segmentectomies 4‐5‐7‐8 were performed with the IRHV‐sparing technique on patients with HCC and significant fibrosis or cirrhosis. Data including demographic information, preoperative evaluations, postoperative outcomes, and follow‐up results were collected and evaluated.

Results

All patients survived and recovered from hepatectomy. The incidence of complications was higher in cirrhotic patients. The 1‐year overall survival rate was 80 %, and the 1‐year disease free survival rate was 60 %.

Conclusions

IRHV‐preserving major right hepatectomy increases the resectability of HCC. Intraoperative ultrasonography is recommended to facilitate protection of the IRHV. This technique is safe with careful preoperative evaluation and meticulous perioperative care. The short‐term outcome of IRHV‐preserving liver resections is satisfactory.
Minding the gaps: metabolomics mends functional genomics
Authors: Rhee Kyu
Published: October 2013

Two recent studies in PNAS and Nat Chem Biol highlight the power of modern mass‐spectrometry techniques for enzyme discovery applied to microbiology. In so doing, they have uncovered new potential targets for the treatment of tuberculosis.
Multiple pedestrians tracking algorithm by incorporating histogram of oriented gradient detections
Authors: Sun Li , Liu Guizhong , Liu Yiqing
Published: October 2013

The authors propose an effective algorithm for multiple pedestrians tracking, which is constructed in the framework of particle filtering, and it is based on the combination of online boosting tracker and the histogram of oriented gradient (HOG) descriptor for human detection. The combination for the detector and tracker lies on following aspects. First, each detection result is associated to a tracker implemented by the online boosting, which gives the authors scheme robustness for multiple similar objects and then, the output of support vector machine classifier based on HOG is dynamically fused as a component in the observation metric in particle filtering, which makes the tracker more accurate in some difficult conditions. Finally, the states of some particles are replaced by the state given by the detector, so that the tracker can recover from failure quickly. Experiments show the effectiveness of their scheme.
Automated photo‐consistency test for voxel colouring based on fuzzy adaptive hysteresis thresholding
Authors: Barhoumi Walid , Bakkay Mohamed Chafik , Zargouba Ezzeddine
Published: October 2013

Voxel colouring is a popular method for reconstructing a three‐dimensional surface model from a set of a few calibrated images. However, the reconstruction quality is largely dependent on a thresholding procedure allowing the authors to decide, for each voxel, whether it is photo‐consistent or not. Nevertheless, in addition to the absence of any information on the neighbouring voxels during the photo‐consistency test, it is extremely difficult to define the appropriate thresholds, which should be precise and stable on all surface voxels. In this study, the authors propose an automated photo‐consistency test based on fuzzy hysteresis thresholding. The proposed method allows the incorporation of the spatial coherence during volume reconstruction, while avoiding ‘floating voxels’ and holes. Moreover, the ambiguity of choosing the thresholds is extremely minimised by defining a fuzzy degree of membership of each voxel into the class of consistent voxels. Also, there is no need for preset thresholds since the hysteresis ones are defined automatically and adaptively depending on the number of images that the voxel is projected onto. Preliminary results are very promising and demonstrate that the proposed method performs automatically precise and smooth volumetric scene reconstruction.
Structural investigation of silicon nanowires with grazing incidence small angle X‐ray scattering
Authors: Buttard Denis , Schülli Tobias , Oehler Fabrice , Gentile Pascal
Published: October 2013

Presented is a structural investigation of silicon nanowires, which is conducted with grazing incidence small angle X‐ray scattering. The morphology of the wires is analysed following experimental measurements. Three diameters (50, 100 and 200 nm) are investigated in relation to the aspect ratio of the wires (length 25 µm). Periodic fringes because of the weak distribution of the diameter are observed on the experimental images. The asymptotic behaviour of the scattering signal along the qy direction is also analysed and presented.
Enhancing fluorescent response of immunosensing by a dielectrophoresis chip with transparent electrodes and microcavities array
Authors: Chuang Cheng‐Hsin , Ju Jing‐Wei , Huang Yao‐Wei
Published: October 2013

Microelectrodes used in dielectrophoresis (DEP) chips are mostly made of metal materials; however, the metal electrodes can induce extra background noise as observed in a fluorescence microscope. Currently, the fluorescent response still dominates the indicators of immunoassays; therefore it is important to eliminate the extra background noise of the fluorescence response generated by metal electrodes for an immunosensor. In this reported study, a transparent conductive material, indium tin oxide (ITO), was employed in the fabrication of DEP electrodes, and the fluorescent responses of a DEP chip with transparent electrodes were compared with an identical DEP chip with conventional Au electrodes during an immunoassay. According to the experimental results, the enhancement of the fluorescent response of the DEP chip with ITO electrodes was greater than the values of the DEP chip with Au electrodes; about 1.57 times and 1.44 times for the immunosensing of 10 and 1 nm bovine serum albumin (BSA), respectively. In addition, by applying the DEP force during the immunosensing, the fluorescent response was also enhanced because of the condensation ability to BSA by the DEP force. Consequently, a DEP chip with transparent ITO electrodes and a microcavities array has been demonstrated, and the background noise of the fluorescence response can be eliminated to enhance the sensitivity of immunosensing.
Funktionsweise und Auswirkungen des Referenzpreissystems bei Impfstoffen nach §130a Abs. 2 SGB V: eine Analyse am Beispiel der Grippeimpfstoffe
Authors: Barth J. , Hammerschmidt T. , Vollmar J. , Bierbaum M. , Schöffski O.
Published: October 2013

Am 01. Januar 2011 ist das Gesetz zur Neuordnung des Arzneimittelmarktes (Arzneimittelmarktneuordnungsgesetz, AMNOG) in Kraft getreten. In diesem Rahmen wurde für den Impfstoffmarkt ein Referenzpreissystem eingeführt um die deutschen Impfstoffpreise an das als niedriger vermutete Preisniveau anderer Staaten der europäischen Union (EU) anzupassen. Im Folgenden wird die Umsetzung, die Funktionsweise und die Auswirkungen dieses neuen Systems beschrieben. Des Weiteren wird anhand des Beispiels der Grippeimpfstoffe analysiert, welchen Einfluss die Referenzpreise auf das Preisgefüge haben.

Das Referenzpreissystem wird anhand des Gesetzes zur Neuordnung des Arzneimittelmarktes und des Schreibens des Spitzenverbandes Bund der Krankenkassen (GKV-Spitzenverband, GKV-SV) vom 22. Juni 2011 an die Verbände der Arzneimittelhersteller und Arzneimittelimporteure beschrieben. Der Analyse der Impfstoffpreise liegen die Daten des i:data-Report (Stand: 01. September 2011) des ifap Service-Instituts zugrunde.

Der europäische Referenzpreis eines Impfstoffes wird als Durchschnittspreis aus den tatsächlich gültigen Abgabepreisen des entsprechenden Impfstoffes in den 4 Ländern der europäischen Union, deren Bruttonationaleinkommen dem deutschen am nächsten kommt und in denen der Impfstoff vertrieben wird, berechnet. Die hierzu herangezogenen Preise werden dabei mit den Umsatzanteilen und Kaufkraftparitäten (KKP) für Gesundheitspflege der jeweiligen Länder gewichtet. Die vorliegende Analyse weist darauf hin, dass insbesondere die praktische Umsetzung des Referenzpreissystems weiter verbessert und konkretisiert werden sollte. Zum einen sollte die Berechnung der Referenzpreise durch den GKV-SV so ausgestaltet werden, dass eine Vergleichbarkeit der Preise ­gewährleistet ist. Außerdem bestehen erhebliche Probleme bei der Abrechnung der Abschläge, da in der Dokumentation der impfenden Ärzte zunächst nicht unterschieden werden konnte, ob eine Impfung als Pflicht- oder Satzungsleistung erbracht wurde. Der Vergleich der Herstellerabgabepreise der einzelnen Grippeimpfstoffe mit den entsprechenden Referenzpreisen zeigt jedoch sowohl bei den Einzelpackungen als auch bei den Zehn­erpackungen nach Einführung des Referenzpreissystems eine Vergrößerung der bereits bestehenden Preisunterschiede, die sich im wettbewerblichen System entwickelt haben.

Bei der Umsetzung des Referenzpreissystems besteht weiterhin Verbesserungsbedarf. Bei den Grippe­impfstoffen kann voraussichtlich durch das Referenzieren eine Reduktion der Ausgaben für die GKV erreicht werden, allerdings wird das wettbewerbliche Preisniveau verzerrt.
Investigation of a compact coaxially fed switched oscillator
Authors: Wang Yuwei , Chen Dongqun , Zhang Jiande , Cao Shengguang , Li Da , Liu Chebo
Published: October 2013

To generate a relative high frequency mesoband microwave, a compact coaxially fed transmission line switched oscillator with high voltage capability is investigated. The characteristic impedance and voltage capability of the low impedance transmission line (LITL) have been analyzed. It is shown that the working voltage of the oscillator can reach up to 200 kV when it is filled by pressurized nitrogen and charged by a nanosecond driving source. By utilizing a commercial electromagnetic simulation code, the transient performance of the switched oscillator with a lumped resistance load is simulated. It is illustrated that the center frequency of the output signal reaches up to ∼0.6 GHz when the spark gap practically closes with a single channel. Besides, the influence of the closing mode and rapidity of the spark gap, the permittivity of the insulator at the output end of the LITL, and the load impedance on the transient performance of the designed oscillator has been analyzed in quantification. Finally, the good transient performance of the switched oscillator has been preliminarily proved by the experiment.
Solving the Schrödinger eigenvalue problem by the imaginary time propagation technique using splitting methods with complex coefficients
Authors: Bader Philipp , Blanes Sergio , Casas Fernando
Published: October 2013

The Schrödinger eigenvalue problem is solved with the imaginary time propagation technique. The separability of the Hamiltonian makes the problem suitable for the application of splitting methods. High order fractional time steps of order greater than two necessarily have negative steps and cannot be used for this class of diffusive problems. However, there exist methods which use fractional complex time steps with positive real parts which can be used with only a moderate increase in the computational cost. We analyze the performance of this class of schemes and propose new methods which outperform the existing ones in most cases. On the other hand, if the gradient of the potential is available, methods up to fourth order with real and positive coefficients exist. We also explore this case and propose new methods as well as sixth-order methods with complex coefficients. In particular, highly optimized sixth-order schemes for near integrable systems using positive real part complex coefficients with and without modified potentials are presented. A time-stepping variable order algorithm is proposed and numerical results show the enhanced efficiency of the new methods.
Development of microcracks in hydrogen-implanted silicon substrates
Authors: Penot Jean-Daniel , Massy Damien , Rieutord François , Mazen Frederic , Reboh Shay , Madeira Florence , Capello Luciana , Landru Didier , Kononchuk Oleg
Published: October 2013

The development of microcracks in hydrogen-implanted silicon has been studied up to the final split using optical microscopy and mass spectroscopy. It is shown that the amount of gas released when splitting the material is proportional to the surface area of microcracks. This observation is interpreted as a signature of a vertical collection of the available gas. The development of microcracks is modeled taking into account both diffusion and mechanical crack propagation. The model reproduces many experimental observations such as the dependence of split time upon temperature and implanted dose.
Supersaturating silicon with transition metals by ion implantation and pulsed laser melting
Authors: Recht Daniel , Smith Matthew J. , Charnvanichborikarn Supakit , Sullivan Joseph T. , Winkler Mark T. , Mathews Jay , Warrender Jeffrey M. , Buonassisi Tonio , Williams James S. , Gradečak Silvija , Aziz Michael J.
Published: September 2013

We investigate the possibility of creating an intermediate band semiconductor by supersaturating Si with a range of transition metals (Au, Co, Cr, Cu, Fe, Pd, Pt, W, and Zn) using ion implantation followed by pulsed laser melting (PLM). Structural characterization shows evidence of either surface segregation or cellular breakdown in all transition metals investigated, preventing the formation of high supersaturations. However, concentration-depth profiling reveals that regions of Si supersaturated with Au and Zn are formed below the regions of cellular breakdown. Fits to the concentration-depth profile are used to estimate the diffusive speeds, vD, of Au and Zn, and put lower bounds on vD of the other metals ranging from 102 to 104 m/s. Knowledge of vD is used to tailor the irradiation conditions and synthesize single-crystal Si supersaturated with 1019 Au/cm3 without cellular breakdown. Values of vD are compared to those for other elements in Si. Two independent thermophysical properties, the solute diffusivity at the melting temperature, Ds(Tm), and the equilibrium partition coefficient, ke, are shown to simultaneously affect vD. We demonstrate a correlation between vD and the ratio Ds(Tm)/ke0.67, which is exhibited for Group III, IV, and V solutes but not for the transition metals investigated. Nevertheless, comparison with experimental results suggests that Ds(Tm)/ke0.67 might serve as a metric for evaluating the potential to supersaturate Si with transition metals by PLM.
Side-chain effects on the solution-phase conformations and charge photogeneration dynamics of low-bandgap copolymers
Authors: Huo Ming-Ming , Liang Ran , Xing Ya-Dong , Hu Rong , Zhao Ning-Jiu , Zhang Wei , Fu Li-Min , Ai Xi-Cheng , Zhang Jian-Ping , Hou Jian-Hui
Published: September 2013

Solution-phase conformations and charge photogeneration dynamics of a pair of low-bandgap copolymers based on benzo[1,2-b:4,5-b′]dithiophene (BDT) and thieno[3,4-b]thiophene (TT), differed by the respective carbonyl (-C) and ester (-E) substituents at the TT units, were comparatively investigated by using near-infrared time-resolved absorption (TA) spectroscopy at 25 °C and 120 °C. Steady-state and TA spectroscopic results corroborated by quantum chemical analyses prove that both PBDTTT-C and PBDTTT-E in chlorobenzene solutions are self-aggregated; however, the former bears a relatively higher packing order. Specifically, PBDTTT-C aggregates with more π-π stacked domains, whereas PBDTTT-E does with more random coils interacting strongly at the chain intersections. At 25 °C, the copolymers exhibit comparable exciton lifetimes (∼1 ns) and fluorescence quantum yields (∼2%), but distinctly different charge photogeneration dynamics: PBDTTT-C on photoexcitation gives rise to a branching ratio of charge separated (CS) over charge transfer (CT) states more than 20% higher than PBDTTT-E does, correlating with their photovoltaic performance. Temperature and excitation-wavelength dependent exciton/charge dynamics suggest that the CT states localize at the chain intersections that are survivable up to 120 °C, and that the excitons and the CS states inhabit the stretched strands and the also thermally robust orderly stacked domains. The stable self-aggregation structures and the associated primary charge dynamics of the PBDTTT copolymers in solutions are suggested to impact intimately on the morphologies and the charge photogeneration efficiency of the solid-state photoactive layers.
Single inorganic-organic hybrid photovoltaic nanorod
Authors: Yoo Sang-Hoon , Liu Lichun , Ku Tea-Woong , Hong Soonchang , Whang Dongmok , Park Sungho
Published: October 2013

We demonstrate that single photovoltaic (PV) nanorods can be readily fabricated by electrochemical processing in solution-phase under ambient conditions. A porous Au nanorod electrode in the core of the PV nanorod was central to both its structural formation and superior performance. We examined an intrinsically conducting polymer (polypyrrole) and an inorganic semiconductor (cadmium selenide) as precursor materials. Through an extremely simple and cost-effective fashioning process (solution-phase, room temperature), unadorned PV nanorods with up to 1.1% power conversion efficiency were obtained.
Limiting diffusion current at rotating disk electrode with dense particle layer
Authors: Weroński P. , Nosek M. , Batys P.
Published: September 2013

Exploiting the concept of diffusion permeability of multilayer gel membrane and porous multilayer we have derived a simple analytical equation for the limiting diffusion current at rotating disk electrode (RDE) covered by a thin layer with variable tortuosity and porosity, under the assumption of negligible convection in the porous film. The variation of limiting diffusion current with the porosity and tortuosity of the film can be described in terms of the equivalent thickness of stagnant solution layer, i.e., the average ratio of squared tortuosity to porosity. In case of monolayer of monodisperse spherical particles, the equivalent layer thickness is an algebraic function of the surface coverage. Thus, by means of cyclic voltammetry of RDE with a deposited particle monolayer we can determine the monolayer surface coverage. The effect of particle layer adsorbed on the surface of RDE increases non-linearly with surface coverage. We have tested our theoretical results experimentally by means of cyclic voltammetry measurements of limiting diffusion current at the glassy carbon RDE covered with a monolayer of 3 μm silica particles. The theoretical and experimental results are in a good agreement at the surface coverage higher than 0.7. This result suggests that convection in a monolayer of 3 μm monodisperse spherical particles is negligibly small, in the context of the coverage determination, in the range of very dense particle layers.
High-current long-duration uniform electron beam generation in a diode with multicapillary carbon-epoxy cathode
Authors: Queller T. , Gleizer J. Z. , Krasik Ya. E.
Published: October 2013

The results of reproducibly generating an electron beam with a current density of up to 5 kA/cm2, without the cathode-anode gap being shorted by the plasma formed inside the cathode carbon-epoxy capillaries, in a ∼350 kV, ∼600 ns diode, with and without an external guiding magnetic field, are presented. The cathode sustained hundreds of pulses without degradation of its emission properties. Time- and space-resolved emissions of the plasma and spectroscopy analyses were used to determine the cathode plasma's density, temperature, and expansion velocity.
Phase behavior of hard spherical caps
Authors: Cinacchi Giorgio
Published: October 2013

This work reports on the phase behavior of hard spherical caps in the interval of particle shapes delimited by the hard platelet and hemispherical cap models. These very simple model colloidal particles display a remarkably complex phase behavior featuring a competition between isotropic-nematic phase separation and clustering as well as a sequence of structures, from roundish to lacy aggregates to no ordinary hexagonal columnar mesophases, all characterized by groups of particles tending to arrange on the same spherical surface. This behavior parallels that one of many molecular systems forming micelles but here it is purely entropy-driven.
Mechanisms of InAs/GaAs quantum dot formation during annealing of In islands
Authors: Huang S. , Kim S. J. , Levy R. , Pan X. Q. , Goldman R. S.
Published: September 2013

We have examined the formation mechanisms of InAs quantum dots (QDs) via annealing In islands under As flux. We report two distinct mechanisms, droplet epitaxy (DE) and solid phase epitaxy (SPE), which depend on As surface coverage. On c(4 × 4) GaAs surfaces, QDs form by DE. For c(4 × 4)α, one-to-one conversion from In islands to InAs QDs is observed. For c(4 × 4)β, lower densities of larger QDs are observed, presumably due to enhanced In surface diffusion in the absence of metastable Ga-As dimers. For the As capped surface, In deposition leads to an amorphous film, from which QDs nucleate by SPE during annealing.
The compressibility and surface tension product of molten salts
Authors: Marcus Yizhak
Published: October 2013

Products of the isothermal compressibility, κT, and the surface tension, σ, that have been discussed in the literature for liquids in general are shown for over 60 molten salts. The applications of the scaled particle theory of Mayer and the simplified corresponding states correlation of Harada et al. [Ind. Eng. Chem. Fund. 22, 116 (1983)] lead to calculated values twice as large as the experimental ones. Separate correlations in this paper of κT and of σ with the cohesive energy density lead to κTσ products that are commensurate with the experimental values for many of the molten salts, beyond the few 1:1 molten salts that have been dealt with previously.
Effects of ferroelectric-poling-induced strain on magnetic and transport properties of La0.67Ba0.33MnO3 thin films grown on (111)-oriented ferroelectric substrates
Authors: Zhu Q. X. , Zheng M. , Yang M. M. , Li X. M. , Wang Y. , Shi X. , Chan H. L. W. , Luo H. S. , Li X. G. , Zheng R. K.
Published: September 2013

La0.67Ba0.33MnO3 thin films were epitaxially grown on (111)-oriented 0.31Pb(In1/2Nb1/2)O3-0.35Pb(Mg1/3Nb2/3)O3-0.34PbTiO3 ferroelectric single-crystal substrates. During ferroelectric poling and polarization rotation, the resistance of La0.67Ba0.33MnO3 films tracks the electric-field-induced in-plane strain of substrates effectively, implying strain-mediated coupling. Upon poling along the [111] direction, ferromagnetism is suppressed for T < 175 K, but enhanced for T > 175 K, which is explained by magnetoelastic coupling that modifies the film's magnetic anisotropy. Our findings also show that the magnetic field has an opposite effect on the strain-tunability of resistance [i.e.,(ΔR/R)strain] above and below the Curie temperature TC, which is interpreted within the framework of phase separation.
An all solid-state high-voltage ns trigger generator based on magnetic pulse compression and transmission line transformer
Authors: Lin Jiajin , Yang Jianhua , Zhang Jiande , Chen Xinbing
Published: October 2013

Innovative design of an all solid-state high-voltage ns trigger generator, based on magnetic pulse compression and transmission line transformer, is presented. The repetitive trigger pulse generator was developed to trigger a 700 kV trigatron, which has been used to pulse a repetitive intense electron beam accelerator with Tesla transformer charged double pulse forming lines (PFLs). Experimental results show that the trigger pulse generator could produce 180 kV 65 ns duration pulses with a rise time of 20 ns. The repetitive trigger pulses have nice uniform in the voltage waveform. The control time jitter is less then 3 ns. Owing to its good stability and low time jitter, the high-voltage trigger generator is an excellent candidate to trigger the repetitive accelerator.
Nanopatterning and tuning of optical taper antenna apex for tip-enhanced Raman scattering performance
Authors: Kharintsev S. S. , Rogov A. M. , Kazarian S. G.
Published: October 2013

This paper focuses on finding optimal electrochemical conditions from linear sweep voltammetry analysis for preparing highly reproducible tip-enhanced Raman scattering (TERS) conical gold tips with dc-pulsed voltage etching. Special attention is given to the reproducibility of tip apex shapes with different etchant mixtures. We show that the fractional Brownian motion model enables a mathematical description of the decaying current kinetics during the whole etching process up to the cutoff event. Further progress in preparation of highly reproducible smooth and sharp tip apexes is related to the effect of an additive, such as isopropanol, to aqueous acids. A finite-difference time-domain method based near-field analysis provides evidence that TERS performance depends critically on tip orientation relative to a highly focused laser beam. A TERS based criterion for recognizing gold tips able to couple/decouple optical near- and far-fields is proposed.
Lead-free piezoelectric ceramics based on (0.97 − x)K0.48Na0.52NbO3-0.03Bi0.5(Na0.7K0.2Li0.1)0.5ZrO3-xB0.5Na0.5TiO3 ternary system
Authors: Cheng Xiaojing , Wu Jiagang , Wang Xiaopeng , Zhang Binyu , Zhu Jianguo , Xiao Dingquan , Wang Xiangjian , Lou Xiaojie , Liang Wenfeng
Published: October 2013

In this work, the ternary system of potassium-sodium niobate has been designed to enhance the piezoelectric properties without sacrificing the Curie temperature greatly, and (0.97 − x)K0.48Na0.52NbO3-0.03Bi0.5(Na0.7K0.2Li0.1)0.5ZrO3-xB0.5Na0.5TiO3 ceramics have been prepared by the conventional solid-state method. The effect of B0.5Na0.5TiO3 content on the microstructure and electrical properties of the ceramics is studied. The phase diagram shows a phase boundary of the rhombohedral-tetragonal (R-T) phase coexistence in the composition range of 0.5% < x < 1.5%, and then an enhanced dielectric, ferroelectric, and piezoelectric behavior is obtained at such a phase boundary zone. The ceramic with x = 0.01 has an optimum electrical behavior of d33 ∼ 285 pC/N, kp ∼ 0.40, εr ∼ 1235, tan δ ∼ 0.031, Pr ∼ 14.9 μC/cm2, and Ec ∼ 15.2 kV/cm, together with a high Curie temperature of ∼347 °C. The large d33 in such a ternary system is due to a composition-induced R-T phase transition and a higher ɛrPr, and the thermal stability performance is strongly dependent on the phase structure. As a result, the design of the ternary system is an effective way to enhance the piezoelectric properties of potassium-sodium niobate materials.
Plasma relaxation mechanics of pulsed high power microwave surface flashover
Authors: Beeson S. , Dickens J. , Neuber A.
Published: October 2013

Microwave transmission and reflection characteristics of pulsed radio frequency field generated plasmas are elucidated for air, N2, and He environments under pressure conditions ranging from 10 to 600 torr. The pulsed, low temperature plasma is generated along the atmospheric side of the dielectric boundary between the source (under vacuum) and the radiating environment with a thickness on the order of 5 mm and a cross sectional area just smaller than that of the waveguide. Utilizing custom multi-standard waveguide couplers and a continuous low power probing source, the scattering parameters were measured before, during, and after the high power microwave pulse with emphasis on the latter. From these scattering parameters, temporal electron density estimations (specifically the longitudinal integral of the density) were calculated using a 1D plane wave-excited model for analysis of the relaxation processes associated. These relaxation characteristics ultimately determine the maximum repetition rate for many pulsed electric field applications and thus are applicable to a much larger scope in the plasma community than just those related to high power microwaves. This manuscript discusses the diagnostic setup for acquiring the power measurements along with a detailed description of the kinematic and chemical behavior of the plasma as it decays down to its undisturbed state under various gas type and pressure conditions.
Wide-bandwidth charge sensitivity with a radio-frequency field-effect transistor
Authors: Nishiguchi Katsuhiko , Yamaguchi Hiroshi , Fujiwara Akira , van der Zant Herre S. J. , Steele Gary A.
Published: October 2013

We demonstrate high-speed charge detection at room temperature with single-electron resolution by using a radio-frequency field-effect transistor (RF-FET). The RF-FET combines a nanometer-scale silicon FET with an impedance-matching circuit composed of an inductor and capacitor. Driving the RF-FET with a carrier signal at its resonance frequency, small signals at the transistor's gate modulate the impedance of the resonant circuit, which is monitored at high speed using the reflected signal. The RF-FET driven by high-power carrier signals enables a charge sensitivity of 2 × 10−4 e/Hz0.5 at a readout bandwidth of 20 MHz.
Thermal spin injection and accumulation in CoFe/MgO tunnel contacts to n-type Si through Seebeck spin tunneling
Authors: Jeon Kun-Rok , Min Byoung-Chul , Park Seung-Young , Lee Kyeong-Dong , Song Hyon-Seok , Park Youn-Ho , Shin Sung-Chul
Published: October 2013

We report the thermal spin injection and accumulation in crystalline CoFe/MgO tunnel contacts to n-type Si through Seebeck spin tunneling (SST). With the Joule heating (laser heating) of Si (CoFe), the thermally induced spin accumulation is detected by means of the Hanle effect for both polarities of the temperature gradient across the tunnel contact. The magnitude of the thermal spin signal scales linearly with the heating power, and its sign is reversed as we invert the temperature gradient, demonstrating the major features of SST and thermal spin accumulation. Based on a quantitative comparison of the thermal and electrical spin signals, the thermal spin injection through SST is suggested as an effective route to inject the spin accumulation.
Demonstrating 1 nm-oxide-equivalent-thickness HfO2/InSb structure with unpinning Fermi level and low gate leakage current density
Authors: Trinh Hai-Dang , Lin Yueh-Chin , Nguyen Minh-Thuy , Nguyen Hong-Quan , Duong Quoc-Van , Luc Quang-Ho , Wang Shin-Yuan , Nguyen Manh-Nghia , Yi Chang Edward
Published: October 2013

In this work, the band alignment, interface, and electrical characteristics of HfO2/InSb metal-oxide-semiconductor structure have been investigated. By using x-ray photoelectron spectroscopy analysis, the conduction band offset of 1.78 ± 0.1 eV and valence band offset of 3.35 ± 0.1 eV have been extracted. The transmission electron microscopy analysis has shown that HfO2 layer would be a good diffusion barrier for InSb. As a result, 1 nm equivalent-oxide-thickness in the 4 nm HfO2/InSb structure has been demonstrated with unpinning Fermi level and low leakage current of 10−4 A/cm−2. The Dit value of smaller than 1012 eV−1cm−2 has been obtained using conduction method.
Broadband ferromagnetic resonance characterization of GaMnAs thin films
Authors: Ben Hamida A. , Sievers S. , Pierz K. , Schumacher H. W.
Published: October 2013

The precessional magnetization dynamics of GaMnAs thin films are characterized by broadband network analyzer ferromagnetic resonance (FMR) in a coplanar geometry at cryogenic temperatures. The FMR frequencies are characterized as function of in-plane field angle and field amplitude. Using an extended Kittel model of the FMR dispersion, the magnetic film parameters such as saturation magnetization and anisotropies are derived. The modification of the FMR behavior and of the magnetic parameters of the thin film upon annealing is analyzed.
Evidence of electrochemical resistive switching in the hydrated alumina layers of Cu/CuTCNQ/(native AlOx)/Al junctions
Authors: Knorr Nikolaus , Bamedi Ameneh , Karipidou Zoi , Wirtz René , Sarpasan Mustafa , Rosselli Silvia , Nelles Gabriele
Published: October 2013

We have investigated bipolar resistive switching of Cu/CuTCNQ/Al cross-junctions in both vacuum and different gas environments. While the generally observed S-shaped I-V hysteresis was reproduced in ambient air, it was reversibly suppressed in well-degassed samples in vacuum and in dry N2. The OFF-switching currents in ambient air peaked when approximately +2.6 V was applied to the Al electrode at low voltage sweep rates. OFF-switching at constant bias was accelerated in humid and oxygen-rich atmospheres. For unbiased samples stored in air, ON-state (RON) and OFF-state (ROFF) resistances increased with time, and RON surpassed the initial ROFF after approximately one week. Retention times were enhanced for samples stored in vacuum and those with a larger cross-junction area. We suggest that resistive switching occurs in a hydrated native alumina layer at the CuTCNQ/Al interface that grows in thickness during exposure to ambient humidity: ON-switching by electrochemical metallization of free Al and/or Cu ions and OFF-switching by anodic oxidation of the Al electrode and previously grown metal filaments.
Measurements of the divergence of fast electrons in laser-irradiated spherical targets
Authors: Yaakobi B. , Solodov A. A. , Myatt J. F. , Delettrez J. A. , Stoeckl C. , Froula D. H.
Published: October 2013

In recent experiments using directly driven spherical targets on the OMEGA laser system, the energy in fast electrons was found to reach ∼1% of the laser energy at an irradiance of ∼1.1 × 1015 W/cm2. The fraction of these fast electrons absorbed in the compressed fuel shell depends on their angular divergence. This paper describes measurements of this divergence deduced from a series of shots where Mo-coated shells of increasing diameter (D) were suspended within an outer CH shell. The intensity of the Mo–Kα line and the hard x-ray radiation were found to increase approximately as ∼D2, indicating wide divergence of the fast electrons. Alternative interpretations of these results (electron scattering, radiation excitation of Kα, and an electric field due to return current) are shown to be unimportant.
Surface chemistry experiments speed up
Authors: Miller Johanna L.
Published: October 2013

A new camera makes it possible to collect angular information about all products of a reaction at once.
Aging Faces and Aging Perceivers: Young and Older Adults are Less Sensitive to Deviations from Normality in Older Than in Young Adult Faces
Authors: Short Lindsey A , Mondloch Catherine J
Published: October 2013

Past studies examining the other-age effect, the phenomenon in which own-age faces are recognized more accurately than other-age faces, are limited in number and report inconsistent results. Here we examine whether the perceptual system is preferentially tuned to differences among young adult faces. In experiment 1 young (18–25 years) and older adult (63–87 years) participants were shown young and older face pairs in which one member of each pair was undistorted and the other had compressed or expanded features. Participants indicated which member of each pair was more normal and which was more expanded. Both age groups were more accurate when tested with young compared with older faces—but only when judging normality. In experiment 2 we tested a separate group of young adults on the same two tasks but with upright and inverted face pairs to examine the differential pattern of results between the normality and discrimination tasks. Inversion impaired performance on the normality task but not the discrimination task and eliminated the young adult advantage in the normality task. Collectively, these results suggest that the face processing system is optimized for young adult faces and that abundant experience with older faces later in life does not reverse this perceptual tuning.
On the Generality of the Topological Theory of Visual Shape Perception
Authors: Kanbe Fumio
Published: October 2013

This study used a series of six closely related experiments to examine whether individuals use topological structures to discriminate figures. Strict control was exerted over the selection of stimuli, which were a specific type of randomly generated lined figures that can be classified using isomorphic sets defined by graph theory. Any two figures within an isomorphic set possessed the same topological structure. The experiments described here used a same/different discrimination task with simultaneously presented pairs of figures: (a) identical pairs (Id pairs), in which each pair of figures had the same topological and superficial properties; (b) nonidentical and isomorphic pairs (Iso pairs), in which each pair had the same topological but different superficial properties; and (c) nonidentical and nonisomorphic pairs (Noniso pairs), in which each pair had different topological properties. Within these experiments I varied the conditions related to the intersecting line segments, presentation of points defining each figure, figure complexity, stimulus aspect ratios, and the parity of the total line-segment lengths between the figures in each pair. These variations showed that the latencies for making accurate discriminations were shorter for Noniso pairs than for Iso pairs, suggesting that individuals are sensitive to topology when distinguishing figures.