bluuebunny/crossref_metadata_2025 huggingface dataset:
Artificial Antigen‐Presenting Interfaces in the Service of Immunology
Authors: Platzman Ilia , Janiesch Jan‐Willi , Matić Jovana , Spatz Joachim P.
Published: October 2013

While the beneficial impact of modifying and/or targeting T lymphocytes is becoming increasingly accepted in the treatment of different diseases, the road towards cell‐based immunotherapy is still long and winding. Major challenges that remain include, amongst others, the guidance and exquisite regulation of immune processes ex vivo. In part, this is due to the difficulties of simulating ex vivo the intimate cellular interactions that occur between T cells and antigen‐presenting cells (APCs). The fate of T cells is not solely regulated by the presence of certain molecules on the surface of APCs but also by their density and spatial distribution on the micro‐ and nanometric scale. Moreover, mechanical properties of APCs and force‐dependent conformational changes during the formation of an immunological synapse (IS; a highly organized supramolecular complex at the T cellAPC interface), play a crucial role in T cell fate regulation. Various different technical means have been developed to create APC substitutes that are able to simulate ex vivo signals originating from naturally occurring APCs. Here, we review the performance of APC surrogates and discuss their contribution to understanding mechanisms underlying the ability of T cells to perform the “intelligent” mission of acquiring, processing and responding to environmental information.
The Evolution of Tumor‐Targeted Drug Delivery: From the EPR Effect to Nanoswimmers
Authors: Zoabi Nour , Golani‐Armon Adi , Zinger Assaf , Reshef Maayan , Yaari Zvi , Vardi‐Oknin Dikla , Shatsberg Zohar , Shomar Aseel , Shainsky‐Roitman Janna , Schroeder Avi
Published: October 2013

Therapeutic nanotechnologies have made great progress over the past decade. Skepticism has been replaced by the understanding that precision at the nanoscale allows improved treatment modalities in humans. Principles for designing tumor‐targeted drug delivery systems are described. At first, the enhanced permeability and retention (EPR) effect was the major targeting mode, with up to 10 % of the injected dose actually reaching tumors. To improve cellular uptake, sugars, antibodies, peptides or other ligands were added to the surface of nanotherapeutics. These can be coupled with external magnetic fields or ultrasonic waves to propel iron oxide or gas‐filled particles towards the disease site. Next‐generation drug delivery systems will be capable of autonomously swimming towards the disease site and penetrating deep tissue, independent of blood or lymphatic flow. This has been shown to some extent with modified, drug‐producing, bacteria. Interestingly, sperm may be nature’s best example of a multifunctional, targeted, high‐fidelity, self‐propelled, delivery system that we can learn from.
Catalytic Oxidative Cyclisation Reactions of 1,6‐Enynes: A Critical Comparison Between Gold and Palladium
Authors: Nunes dos Santos Comprido Laura , Hashmi A. Stephen K.
Published: October 2013

In transition‐metal catalysis, similar reactivities are often described for related metals, thereby resulting in the formation of similar/identical products. However, only in rare cases can similar/identical product be obtained by using non‐related metals. Amongst these reactions is the oxidative cyclisation of 1,6‐enynes by using palladium or gold. Similarities and differences will be discussed with a special focus on the diastereo‐ and enantioselective course of the reaction.
Biomimetic Platforms for Tissue Engineering
Authors: Vunjak‐Novakovic Gordana
Published: October 2013

Bioengineering platforms that combine cell/tissuespecific transport and signaling with precise control of culture conditions and multiparametric insights into the cell function are critical to our efforts to study tissue development, regeneration, and disease under conditions that predict the human in vivo context. Because living cells respond to the entire context of their environment – in vivo and in vitro, under normal and pathological conditions – the biological foundation of our bioengineering designs that is often described as the “biomimetic paradigm” is critical for unlocking the biological potential of the cells. This brief review focuses on some of the key principles for designing and using biologically inspired engineering platforms. Four examples are used to illustrate the designs and applications of biomimetic platforms.
Silk for Drug Delivery Applications: Opportunities and Challenges
Authors: Seib F. Philipp , Kaplan David L.
Published: October 2013

Silk fibers have been used in textiles for more than 5,000 years and as a suturing material for many centuries. The recent development of new applications for silks include drug delivery. An overview of this new field is provided, summarizing the development of emerging drug delivery applications which include silk‐based nanomedicines and transdermal delivery systems We also highlight some of the challenges in developing silk‐based drug delivery systems.
Drug‐Delivery Systems for Tunable and Localized Drug Release
Authors: Timko Brian P. , Kohane Daniel S.
Published: October 2013

Drug‐delivery systems can be designed to provide localized drug release with a variety of customizable release profiles. Passive systems enable sustained, zero‐order release for days or weeks, while remotely triggered systems enable the timing and dose of drug release to be controlled by the patient or physician. Release profiles can be engineered to match the requirements of particular ailments. We review on‐demand drug‐delivery systems that release a therapeutic in response to magnetic, near‐infrared, or UV fields; such systems could extend the capabilities of sustained release systems by incorporating programmed dosing regimens.
Earth's collision with a solar filament on 21 January 2005: Overview
Authors: Kozyra J. U. , Manchester W. B. , Escoubet C. P. , Lepri S. T. , Liemohn M. W. , Gonzalez W. D. , Thomsen M. W. , Tsurutani B. T.
Published: October 2013

On 21 January 2005, one of the fastest interplanetary coronal mass ejections (ICME) of solar cycle 23, containing exceptionally dense plasma directly behind the sheath, hit the magnetosphere. We show from charge‐state analysis that this material was a piece of the erupting solar filament and further, based on comparisons to the simulation of a fast CME, that the unusual location of the filament material was a consequence of three processes. As the ICME decelerated, the momentum of the dense filament material caused it to push through the flux rope toward the nose. Diverging nonradial flows in front of the filament moved magnetic flux to the sides of the ICME. At the same time, reconnection between the leading edge of the ICME and the sheath magnetic fields worked to peel away the outer layers of the flux rope creating a remnant flux rope and a trailing region of newly opened magnetic field lines. These processes combined to move the filament material into direct contact with the ICME sheath region. Within 1 h after impact and under northward interplanetary magnetic field (IMF) conditions, a cold dense plasma sheet formed within the magnetosphere from the filament material. Dense plasma sheet material continued to move through the magnetosphere for more than 6 h as the filament passed by the Earth. Densities were high enough to produce strong diamagnetic stretching of the magnetotail despite the northward IMF conditions and low levels of magnetic activity. The disruptions from the filament collision are linked to an array of unusual features throughout the magnetosphere, ionosphere, and atmosphere. These results raise questions about whether rare collisions with solar filaments may, under the right conditions, be a factor in producing even more extreme events.
Investigating the presence of omeprazole in waters by liquid chromatography coupled to low and high resolution mass spectrometry: degradation experiments
Authors: Boix C. , Ibáñez M. , Sancho J. V. , Niessen W. M. A. , Hernández F.
Published: October 2013

Omeprazole is one of the most consumed pharmaceuticals around the world. However, this compound is scarcely detected in urban wastewater and surface water. The absence of this pharmaceutical in the aquatic ecosystem might be due to its degradation in wastewater treatment plants, as well as in receiving water. In this work, different laboratory‐controlled degradation experiments have been carried out on surface water in order to elucidate generated omeprazole transformation products (TPs). Surface water spiked with omeprazole was subjected to hydrolysis, photo‐degradation under both sunlight and ultraviolet radiation and chlorination. Analyses by liquid chromatography coupled to quadrupole time‐of‐flight mass spectrometry (LC–QTOF MS) permitted identification of up to 17 omeprazole TPs. In a subsequent step, the TPs identified were sought in surface water and urban wastewater by LC–QTOF MS and by LC coupled to tandem mass spectrometry with triple quadrupole. The parent omeprazole was not detected in any of the samples, but four TPs were found in several water samples. The most frequently detected compound was OTP 5 (omeprazole sulfide), which might be a reasonable candidate to be included in monitoring programs rather than the parent omeprazole. Copyright © 2013 John Wiley & Sons, Ltd.
Comparison of the sensitivity of mass spectrometry atmospheric pressure ionization techniques in the analysis of porphyrinoids
Authors: Świder Paweł , Lewtak Jan P. , Gryko Daniel T. , Danikiewicz Witold
Published: October 2013

The porphyrinoids chemistry is greatly dependent on the data obtained in mass spectrometry. For this reason, it is essential to determine the range of applicability of mass spectrometry ionization methods. In this study, the sensitivity of three different atmospheric pressure ionization techniques, electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization, was tested for several porphyrinods and their metallocomplexes. Electrospray ionization method was shown to be the best ionization technique because of its high sensitivity for derivatives of cyanocobalamin, free‐base corroles and porphyrins. In the case of metallocorroles and metalloporphyrins, atmospheric pressure photoionization with dopant proved to be the most sensitive ionization method. It was also shown that for relatively acidic compounds, particularly for corroles, the negative ion mode provides better sensitivity than the positive ion mode. The results supply a lot of relevant information on the methodology of porphyrinoids analysis carried out by mass spectrometry. The information can be useful in designing future MS or liquid chromatography–MS experiments. Copyright © 2013 John Wiley & Sons, Ltd.
Pharmacophore Model Refinement for 11β‐Hydroxysteroid Dehydrogenase Inhibitors: Search for Modulators of Intracellular Glucocorticoid Concentrations
Authors: Vuorinen Anna , Nashev Lyubomir G. , Odermatt Alex , Rollinger Judith M. , Schuster Daniela
Published: October 2013

11β‐Hydroxysteroid dehydrogenases (11β‐HSD) control the intracellular concentrations of glucocorticoids: 11β‐HSD1 converts the inactive cortisone to the active cortisol, and 11β‐HSD2 is responsible for the opposite reaction. Inhibition of 11β‐HSD1 is beneficial in the treatment of metabolic syndrome, whereas 11β‐HSD2 inhibition leads to hypertension. Therefore, 11β‐HSD1 inhibitors should be selective over 11β‐HSD2. To support drug discovery and toxicological studies, we have previously reported pharmacophore models for 11β‐HSD1 and 2 inhibition. These models represent the common chemical features of 11β‐HSD inhibitors, which were used as virtual screening filter. Since new inhibitors are constantly discovered, the quality of the pharmacophore models has to be evaluated in order to maintain a good predictive power. In this study, we report a systematic evaluation and refinement of our pharmacophore model collection. We employed our models for virtual screening, especially focusing on the 11β‐HSD2 inhibition. In total, 42 compounds were biologically evaluated and among these we discovered 17 11β‐HSD inhibitors that decreased the residual enzyme activity to 50% or less at the concentration of 20 µM. The experimental 11β‐HSD1 and 2 readouts from these compounds were used for further model refinement. Evaluation metrics were applied for a quantitative comparison of the old and newly generated models which resulted in a set of improved pharmacophore models offering reliable in silico tools for the identification of novel and selective 11β‐HSD inhibitors.
Inhibitor selectivity between aldo–keto reductase superfamily members AKR1B10 and AKR1B1: Role of Trp112 (Trp111)
Authors: Zhang Liping , Zhang Hong , Zhao Yining , Li Zhe , Chen Shangke , Zhai Jing , Chen Yunyun , Xie Wei , Wang Zhong , Li Qing , Zheng Xuehua , Hu Xiaopeng
Published: October 2013

The antineoplastic target aldo–keto reductase family member 1B10 (AKR1B10) and the critical polyol pathway enzyme aldose reductase (AKR1B1) share high structural similarity. Crystal structures reported here reveal a surprising Trp112 native conformation stabilized by a specific Gln114‐centered hydrogen bond network in the AKR1B10 holoenzyme, and suggest that AKR1B1 inhibitors could retain their binding affinities toward AKR1B10 by inducing Trp112 flip to result in an “AKR1B1‐like” active site in AKR1B10, while selective AKR1B10 inhibitors can take advantage of the broader active site of AKR1B10 provided by the native Trp112 side‐chain orientation.
Inhibition of ADP‐ribosylation suppresses aberrant accumulation of lipidated apolipoprotein B in the endoplasmic reticulum
Authors: Ohsaki Yuki , Cheng Jinglei , Yamairi Kazushi , Pan Xiaoyue , Hussain M. Mahmood , Fujimoto Toyoshi
Published: October 2013

ApoB‐crescent, an endoplasmic reticulum (ER)‐lipid droplet amalgamation structure, is a useful marker to indicate aberrant lipidated apolipoprotein B accumulation in the hepatocyte ER. Blockade of the ER‐to‐Golgi transport by either vesicle transport inhibitors or dominant‐negative Arf1 caused a significant increase in ApoB‐crescents. However, a low concentration of Brefeldin A induced the same result without affecting protein secretion, suggesting ADP‐ribosylation as an additional mechanism. ADP‐ribosylation inhibitors not only suppressed the increase of ApoB‐crescents, but also rapidly dissolved existing ApoB‐crescents. These results implicate the involvement of ADP‐ribosylation in the ApoB‐crescent formation and maintenance process at the ER.
Mood and anxiety disorders, the association with presenteeism in employed members of a general population sample
Authors: Esposito Eleonora , Wang Jian Li , Williams Jeanne V.A. , Patten Scott B.
Published: October 2013

Aims– The term “presenteeism” is used to describe workers who are present in the workforce, but who are not functioning at full capacity. The objective of the study was to describe the impact of mood and anxiety disorders on presenteeism in a population sample.Methods– Random digit dialing was used to select a sample of n= 3345 subjects between the ages of 18 and 64. A computer assisted telephone interview that included theMini Neuropsychiatric Diagnostic Interview(MINI), theStanford Presenteeism Scale6 (SPS-6) and a pharmacoepidemiology module was administered.Results– Among subjects with comorbid mood and anxiety disorders 75.0% reported interference with their work compared with only 13.3% of subjects without mood or anxiety disorders. Mood and anxiety disorders were associated with lower presenteeism ratings. Regression analysis uncovered a significant gender by anxiety disorder interaction, indicating that the effect of anxiety disorders was greater in men than women.Conclusions– This is the first study to report the impact of mental disorders on presenteeism in a general population sample. The results confirm that the problem of presenteeism is not restricted to specific occupational groups, but is instead a widespread problem in the general population.

Declaration of Interest: This study was funded by the Alberta Depression Initiative through the Institute of Health Economics (www.ihe.ab.ca). Dr. Esposito was supported by an International Resident Fellowship from the University of Calgary. Dr. Patten is a Health Scholar with the Alberta Heritage Foundation for Medical Research and a Fellow with the Institute of Health Economics. Dr. Wang is a New Investigator with the Canadian Institutes for Health Research.
Scores und Stadien in der Gastroenterologie
Authors: Mosler Patrick
Published: October 2013

Staging- und Grading-Indizes sind für klinisch tätige Gastroenterologen und Hausärzte von Patienten mit gastroenterologischen Erkrankungen unverzichtbar, da oft nur so die Aktivität einer Erkrankung oder der Erfolg einer Therapie systematisch und reproduzierbar festgelegt werden kann. Genaue Diagnose und adäquate Therapie sind daher oft auf ein akkurates Staging- bzw. Gradingsystem angewiesen. Im klinischen Alltag eines Gastroenterologen spielen die Gastroösophageale Refluxerkrankung, die Peptische Ulkuskrankheit, vaskuläre Erkrankungen des Verdauungstraktes wie Hämorrhoiden oder Ösophagusvarizen sowie die Chronisch-entzündlichen Darmerkrankungen eine wichtige Rolle. Einige der für den klinischen Alltag sowie die Kommunikation zwischen Gastroenterologen und Hausärzten wichtigsten Staging- und Grading-Indizes dieser Erkrankungen wurden hier zusammengefasst.
Scores und Stadien in der Pneumologie
Authors: Kuhn Max
Published: October 2013

Scores und Stadien werden vorgestellt, die sich im klinischen Alltag zur Behandlung von Lungenkrankheiten bewährt haben. Die modifizierte Medical Research Council Dyspnoeskala (mMRC) graduiert die subjektiv empfundene Dyspnoe. Die GOLD-Klassifikationen, der COPD-Assessment Test (CAT) und der BODE-Index sind bei der Betreuung von COPD-Patienten wertvoll. Der revidierte Geneva-Score hilft die Vortest-Wahrscheinlichkeit einer Lungenembolie und der Pulmonary Embolism Severity Index (PESI) den Schweregrad abzuschätzen. Der Epworth Sleepiness Scale gibt Auskunft über die Tagesmüdigkeit bei einem Patienten mit obstruktivem Schlafapnoesyndrom. Der Asthma Controll Test (ACT) zeigt, ob eine antiasthmatische Behandlung genügend wirksam ist.
Using direct numerical simulation to analyze and improve hot-wire probe sensor and array configurations for simultaneous measurement of the velocity vector and the velocity gradient tensor
Authors: Vukoslavčević Petar V. , Wallace James M.
Published: October 2013

Multi-sensor, hot-wire probes of various configurations have been used for 25 years to simultaneously measure the velocity vector and the velocity gradient tensor in turbulent flows. This is the same period in which direct numerical simulations (DNS) were carried out to investigate these flows. Using the first DNS of a turbulent boundary layer, Moin and Spalart [“Contributions of numerical simulation data bases to the physics, modeling and measurement of turbulence,” NASA Technical Memorandum 100022 (1987)] examined, virtually, the performance of a two-sensor X-array probe with the sensors idealized as points in the numerical grid. Subsequently, several investigators have used DNS for similar studies. In this paper we use a highly resolved minimal channel flow DNS, following Jiménez and Moin [“The minimal flow unit in near-wall turbulence,” J. Fluid Mech. 225, 213 (1991)], to study the performance of an 11-sensor probe. Our previous studies of this type have indicated that, on balance, a probe of the design described here may provide the most accurate measurements of many of the statistics formed from the velocity vector and the velocity gradient tensor (rms and skewness values of the velocity and vorticity components as well as the Reynolds shear stress and the dissipation and production rates). The results of the present study show that, indeed, the sensor and array configurations of a probe of this design are considerably better than previous designs that have been used, and they are likely to give reasonably satisfactory results for such measurements with a real probe in a real bounded flow.
Dissociation of chloromethanes upon resonant σ* excitation studied by x-ray scattering
Authors: Bohinc R. , Žitnik M. , Bučar K. , Kavčič M. , Journel L. , Guillemin R. , Marchenko T. , Simon M. , Cao W.
Published: October 2013

The dissociation process following the Cl K-shell excitation to σ* resonances is studied by high resolution spectroscopy of resonant elastic and inelastic x-ray scattering on CH3Cl, CH2Cl2, CHCl3, and CCl4 molecules. Calculations employing the transition potential and Delta-Kohn-Sham DFT approach are in good agreement with the measured total fluorescence yield and show the presence of a second quasidegenerate group of states with σ* character above the lowest σ* unoccupied molecular orbital for molecules with more than one Cl atom. A bandwidth narrowing and a nonlinear dispersion behavior is extracted from the Kα spectral maps for both σ* resonances. The fitted data indicate that the widths of the Franck-Condon distributions for the first and second σ* resonances are comparable for all the molecules under study. In addition, an asymmetric broadening of the emission peaks is observed for resonant elastic x-ray scattering with zero detuning on both σ* resonances. This is attributed to the fast dissociation, transferring about 0.15 of the scattering probability into higher vibrational modes.
Two-component Kramers restricted complete active space self-consistent field method with relativistic effective core potential revisited: Theory, implementation, and applications to spin-orbit splitting of lower p-block atoms
Authors: Kim Inkoo , Lee Yoon Sup
Published: October 2013

The relativistic two-component complete active space self-consistent field theory in Kramers restricted formalism (KRCASSCF) through the framework of the spin-orbit relativistic effective core potential is implemented into the KPACK package. This paper continues the development previously reported [Y. S. Kim and Y. S. Lee, J. Chem. Phys. 119, 12169 (2003)] and extends the theory by means of adding time-reversal symmetry into the relevant expressions so as to complete the course of theoretical development. We retained the usage of elementary spinor excitation operator for defining the spinor rotation operator and derived the gradient and Hessian in simpler forms than previously found. To eliminate redundant computation resulting from repeating sums in the derivatives, a suitable decomposition method is proposed, which also facilitates the implementation. The two-step near second-order approach is employed for convergence. The present implementation is applicable for both closed- and open-shell systems and is used to calculate the atoms of lower p-block. The results for 5p and 6p are in good agreement with the experiments, and those for 7p are comparable to multi-reference configuration interaction results, showing that KRCASSCF is a versatile tool for the relativistic electronic structure calculation of molecules containing moderate-weight through superheavy elements.
Effect of binding to carbon black on the dynamics of 1,4-polybutadiene
Authors: Roh J. H. , Tyagi M. , Hogan T. E. , Roland C. M.
Published: October 2013

The nature of the interactions of polymers at the surface of nanoparticles is crucial to understanding the dynamics and their relation to mechanical properties. The effect of binding (both chemical attachment and physical adsorption) on the local and global dynamics of chain molecules remains a controversial subject. Using neutron scattering and dynamic mechanical spectroscopies, we measured the slow conformational and terminal relaxations, as well as the fast local dynamics, of 1,4-polybutadiene (PBD) containing carbon black (CB) particles. We observed a substantial decrease in the flexibility of bound segments at temperatures through the glass transition temperature, Tg. The longer range motions of the PBD become more suppressed and cooperative as temperature decreases, while the relaxation time of the fast local dynamics is little affected by the CB particles. The mobile fraction of PBD is less sensitive to temperature when bound. Mechanical spectroscopy indicates that both the local segmental dynamics and the global chain modes are slowed by the filler. These results are consistent with transient structural arrest of the slow dynamics of atoms adjacent to the particles.
Do we understand the bubble formation by a single drop impacting upon liquid surface?
Authors: Wang An-Bang , Kuan Chen-Chi , Tsai Pei-Hsun
Published: October 2013

Large bubble formation by a single drop impacting upon a liquid surface with low impact energy is conventionally considered to be unimportant and not a cause for small bubble(s) generation. Our experiments contradict three widely accepted concepts about bubble formation. First, this paper presents results that give evidence of much wider existence of large bubble entrainment. Second, there is no closed characteristic regime for regular large bubble generation. Third, for the first time, there are results of bubble pair generation in sequence that show the direct formation of smaller bubble(s) due to a single large bubble rupturing without external disturbances. Additionally, this work demonstrates that the shape of an oscillating prolate drop at impact is the missing factor that helps predict large bubble formation. At the end, this paper presents a new characteristic map for large bubble formation that is based on the theoretical oscillation model.
Zigzag transitions and nonequilibrium pattern formation in colloidal chains
Authors: Straube Arthur V. , Dullens Roel P. A. , Schimansky-Geier Lutz , Louis Ard A.
Published: October 2013

Paramagnetic colloidal particles that are optically trapped in a linear array can form a zigzag pattern when an external magnetic field induces repulsive interparticle interactions. When the traps are abruptly turned off, the particles form a nonequilibrium expanding pattern with a zigzag symmetry, even when the strength of the magnetic interaction is weaker than that required to break the linear symmetry of the equilibrium state. We show that the transition to the equilibrium zigzag state is always potentially possible for purely harmonic traps. For anharmonic traps that have a finite height, the equilibrium zigzag state becomes unstable above a critical anharmonicity. A normal mode analysis of the equilibrium line configuration demonstrates that increasing the magnetic field leads to a hardening and softening of the spring constants in the longitudinal and transverse directions, respectively. The mode that first becomes unstable is the mode with the zigzag symmetry, which explains the symmetry of nonequilibrium patterns. Our analytically tractable models help to give further insight into the way that the interplay of factors such as the length of the chain, hydrodynamic interactions, thermal fluctuations affects the formation and evolution of the experimentally observed nonequilibrium patterns.
A comparative study of principal component analysis and independent component analysis in eddy current pulsed thermography data processing
Authors: Bai Libing , Gao Bin , Tian Shulin , Cheng Yuhua , Chen Yifan , Tian Gui Yun , Woo W. L.
Published: October 2013

Eddy Current Pulsed Thermography (ECPT), an emerging Non-Destructive Testing and Evaluation technique, has been applied for a wide range of materials. The lateral heat diffusion leads to decreasing of temperature contrast between defect and defect-free area. To enhance the flaw contrast, different statistical methods, such as Principal Component Analysis and Independent Component Analysis, have been proposed for thermography image sequences processing in recent years. However, there is lack of direct and detailed independent comparisons in both algorithm implementations. The aim of this article is to compare the two methods and to determine the optimized technique for flaw contrast enhancement in ECPT data. Verification experiments are conducted on artificial and thermal fatigue nature crack detection.
Measurement system of the Seebeck coefficient or of the electrical resistivity at high temperature
Authors: Rouleau O. , Alleno E.
Published: October 2013

A high temperature Seebeck coefficient or electrical resistivity apparatus has been designed and fabricated to measure sample with typical size ∼10 × 1 × 1 mm3. It can measure both transport properties from 300 K to 1000 K in argon atmosphere. The sample lies transversely on top of two metallic half-cylinders, which contain heating cartridges and allow temperature and thermal gradient control and reversal. The temperature gradient is measured by two type N thermocouples pressed against the upper surface of the sample. The key feature of this apparatus is the disk-shaped junction of each type N thermocouple which strongly improves the thermal contact with the sample. The Seebeck coefficient is obtained by averaging over two measured values with opposite thermal gradient directions (∼±2 K). For the resistivity measurements, the temperature is stabilized and the temperature gradient is actively reduced below 0.2 K to make negligible any spurious thermal voltage. Uncertainties of ∼3% for the Seebeck coefficient and 1% for the resistivity were obtained on Ni samples. The Seebeck coefficient and resistivity have also been measured on a skutterudite sample as small as ∼7 × 1.5 × 0.5 mm3 with very good agreement with literature.
Large-eddy simulation of shock-cooling-film interaction at helium and hydrogen injection
Authors: Konopka Martin , Meinke Matthias , Schröder Wolfgang
Published: October 2013

Laminar helium and hydrogen films at a Mach number 1.3 are injected through a slot into a fully turbulent freestream air flow at a Mach number 2.44. To numerically study by large-eddy simulations the impact of an impinging shock on various cooling films, first, reference solutions without shock impingement are computed and then, the helium and hydrogen cooling films interacting with an oblique shock at a pressure ratio of p3/p1 = 2.5 are analyzed. The comparison of the helium and hydrogen injections without shock shows the hydrogen injection to have a 1.14-fold better cooling effectiveness at 60% of the blowing rate of the helium injection. The shock-cooling-film interaction causes a massive separation bubble that is 23% larger at the hydrogen than at the helium injection. Nevertheless, the shock influenced cooling effectiveness at the hydrogen injection is only 30% reduced compared to a 40% decrease at the helium injection 100 slot heights downstream of the injection. The intense mixing in the shock-cooling-film interaction region shows a more rapid reduction of the helium and hydrogen mass fractions than in the zero-pressure gradient reference configurations. Overall, the cooling effectiveness of the hydrogen film is superior to that of the helium film independent from the streamwise pressure gradient.
Effectiveness of X-ray grating interferometry for non-destructive inspection of packaged devices
Authors: Uehara Masato , Yashiro Wataru , Momose Atsushi
Published: October 2013

It is difficult to inspect packaged devices such as IC packages and power modules because the devices contain various components, such as semiconductors, metals, ceramics, and resin. In this paper, we demonstrated the effectiveness of X-ray grating interferometry (XGI) using a laboratory X-ray tube for the industrial inspection of packaged devices. The obtained conventional absorption image showed heavy-elemental components such as metal wires and electrodes, but the image did not reveal the defects in the light-elemental components. On the other hand, the differential phase-contrast image obtained by XGI revealed microvoids and scars in the encapsulant of the samples. The visibility contrast image also obtained by XGI showed some cracks in the ceramic insulator of power module sample. In addition, the image showed the silicon plate surrounded by the encapsulant having the same X-ray absorption coefficient. While these defects and components are invisible in the conventional industrial X-ray imaging, XGI thus has an attractive potential for the industrial inspection of the packaged devices.
Iterative reconstruction algorithm for analyzer-based phase-contrast computed tomography of hard and soft tissue
Authors: Sunaguchi Naoki , Yuasa Tetsuya , Ando Masami
Published: October 2013

We propose a reconstruction algorithm for analyzer-based phase-contrast computed tomography (CT) applicable to biological samples including hard tissue that may generate conspicuous artifacts with the conventional reconstruction method. The algorithm is an iterative procedure that goes back and forth between a tomogram and its sinogram through the Radon transform and CT reconstruction, while imposing a priori information in individual regions. We demonstrate the efficacy of the algorithm using synthetic data generated by computer simulation reflecting actual experimental conditions and actual data acquired from a rat foot by a dark field imaging system.
Photoelectrical response of hybrid graphene-PbS quantum dot devices
Authors: Huang Y. Q. , Zhu R. J. , Kang N. , Du J. , Xu H. Q.
Published: October 2013

Hybrid graphene-PbS quantum dot devices are fabricated on an n-type silicon substrate capped with a thin SiO2 layer and are characterized by photoelectrical measurements. It is shown that the resistance of the graphene channel in the devices exhibits detectable changes when a laser beam is switched on and off on the quantum dots. The model that explains the observed photoresponse phenomenon is illustrated. We also show that the photoresponse signal, i.e., the photoinduced change in the resistance of the graphene channel can be tuned in both magnitude and sign with a voltage applied to the back gate of the devices and is related to the derivative of the transfer characteristics of the graphene channel. Our work shows that the simple hybrid graphene-PbS quantum dot devices can be employed for photodetection applications.
Comparison on electrically pumped random laser actions of hydrothermal and sputtered ZnO films
Authors: Wang Canxing , Jiang Haotian , Li Yunpeng , Ma Xiangyang , Yang Deren
Published: October 2013

Random lasing (RL) in polycrystalline ZnO films is an intriguing research subject. Here, we have comparatively investigated electrically pumped RL behaviors of two metal-insulator-semiconductor structured devices using the hydrothermal and sputtered ZnO films as the semiconductor components, i.e., the light-emitting layers, respectively. It is demonstrated that the device using the hydrothermal ZnO film exhibits smaller threshold current and larger output optical power of the electrically pumped RL. The morphological characterization shows that the hydrothermal ZnO film is somewhat porous and is much rougher than the sputtered one, suggesting that in the former stronger multiple light scattering can occur. Moreover, the photoluminescence characterization indicates that there are fewer defects in the hydrothermal ZnO film than in the sputtered one, which means that the photons can pick up larger optical gain through stimulated emission in the hydrothermal ZnO film. Therefore, it is believed that the stronger multiple light scattering and larger optical gain contribute to the improved performance of the electrically pumped RL from the device using the hydrothermal ZnO film.
Electronic structures of graphene layers on a metal foil: The effect of atomic-scale defects
Authors: Yan Hui , Liu Cheng-Cheng , Bai Ke-Ke , Wang Xuejiao , Liu Mengxi , Yan Wei , Meng Lan , Zhang Yanfeng , Liu Zhongfan , Dou Rui-fen , Nie Jia-Cai , Yao Yugui , He Lin
Published: October 2013

Here, we report a facile method to generate a high density of atomic-scale defects in graphene on metal foil and show how these defects affect the electronic structures of graphene layers. Our scanning tunneling microscope measurements, complemented by first-principles calculations, reveal that the atomic-scale defects result in both the intervalley and intravalley scattering of graphene. The Fermi velocity is reduced in the vicinity area of the defect due to the enhanced scattering.
Tunable oxygen vacancy configuration by strain engineering in perovskite ferroelectrics from first-principles study
Authors: Yang Q. , Cao J. X. , Zhou Y. C. , Zhang Y. , Ma Y. , Lou X. J.
Published: October 2013

Comprehensive first-principle calculations indicate that the oxygen vacancy (VO) configuration of a prototypical perovskite oxide PbTiO3 (PTO) can be tuned by strain engineering. Remarkably, we found that VO located along the c axis (Vc), normally resulting in a polarization-harming tail-to-tail domain configuration in strain-free PTO (Vcud), can be readily tuned to a polarization-harmless head-to-tail domain configuration (Vcsw) by applying an ab-biaxial compressive strain of 3%. Also, VO located in the ab-plane (Vab), another type of polarization-harmless vacancy, can be stabilized by applying a compressive strain of 2%.
Characteristics of a Direct Current-driven plasma jet operated in open air
Authors: Li Xuechen , Di Cong , Jia Pengying , Bao Wenting
Published: October 2013

A DC-driven plasma jet has been developed to generate a diffuse plasma plume by blowing argon into the ambient air. The plasma plume, showing a cup shape with a diameter of several centimeters at a higher voltage, is a pulsed discharge despite a DC voltage is applied. The pulse frequency is investigated as a function of the voltage under different gap widths and gas flow rates. Results show that plasma bullets propagate from the hollow needle to the plate electrode by spatially resolved measurement. A supposition about non-electroneutral trail of the streamer is proposed to interpret these experimental phenomena.
Evaluation of potential variations around grain boundaries in BaSi2 epitaxial films by Kelvin probe force microscopy
Authors: Baba Masakazu , Tsurekawa Sadahiro , Watanabe Kentaro , Du W. , Toko Kaoru , Hara Kosuke O. , Usami Noritaka , Sekiguchi Takashi , Suemasu Takashi
Published: October 2013

Potential variations around the grain boundaries (GBs) on the surface in undoped n-BaSi2 epitaxial films on Si(111) and Si(001) were analyzed using Kelvin prove force microcopy. The potentials were higher at GBs than those in the BaSi2 grains on Si(111). The average barrier height was approximately 30 meV at the GBs, indicating that the enhanced potentials repulse photogenerated holes so that the charge carrier recombination can be effectively reduced. In contrast, the potentials were smaller at GBs in the BaSi2 on Si(001), and the average barrier heights were approximately 30 and 50 meV along Si[1–10] and [110], respectively.
Enhanced thermoelectric performance in the very low thermal conductivity Ag2Se0.5Te0.5
Authors: Drymiotis Fivos , Day Tristan W. , Brown David R. , Heinz Nicholas A. , Jeffrey Snyder G.
Published: October 2013

In this letter, we report the high-temperature thermoelectric properties of Ag2Se0.5Te0.5. We find that this particular composition displays very low thermal conductivity and competitive thermoelectric performance. Specifically, in the temperature region 520 K ≤ T ≤ 620 K, we observe non-hysteretic behavior between the heating and cooling curves and zT values ranging from 1.2 to 0.8. Higher zT values are observed at lower temperatures on cooling. Our results suggest that this alloy is conducive to high thermoelectric performance in the intermediate temperature range, and thus deserves further investigation.
Relative intensity noise in high speed microcavity laser
Authors: Tan F. , Wu M. K. , Liu M. , Feng M. , Holonyak N.
Published: October 2013

We have fabricated a high speed single mode microcavity laser of the form of oxide-confined vertical cavity surface emitting laser (VCSEL) and achieved an ultralow threshold current (ITH = 0.13 mA at 20 °C) with lasing wavelength at 837 nm. The optical spectrum of the microcavity VCSEL exhibits a mode spacing of 3.1 nm, which is corresponding to an optical modal cavity dimension of 2.5 μm. The device exhibits an enhanced modulation bandwidth of 22.6 GHz and a thermal noise limited laser intensity noise (electrical power spectral density of laser intensity noise below the thermal noise floor −174 dBm/Hz) as a consequence of low power laser operation and reduced mode competition in the microcavity.
Substrate surface corrugation effects on the electronic transport in graphene nanoribbons
Authors: Babaee Touski Shoeib , Pourfath Mahdi
Published: October 2013

In this work, the electronic transport in armchair graphene nanoribbons in the presence of surface corrugation is studied. The non-equilibrium Green's function along with tight-binding model for describing the electronic band structure is employed to investigate the electronic properties of graphene nanoribbons. The effects of surface corrugation parameters, such as corrugation amplitude and correlation length, on the electronic properties of the graphene nanoribbons are studied. The mean free path of carriers is extracted and its dependency on the corrugation amplitude and correlation length is investigated.
The effect of graphene on liquid-crystalline blue phases
Authors: Lavrič M. , Tzitzios V. , Kralj S. , Cordoyiannis G. , Lelidis I. , Nounesis G. , Georgakilas V. , Amenitsch H. , Zidanšek A. , Kutnjak Z.
Published: October 2013

The stabilization of liquid-crystalline blue phases is recently attracting considerable interest because of the envisioned applications in fast optical displays and tunable photonic crystals. We report on the effect of surface-functionalized graphene nanosheets on the blue phase range of a chiral liquid crystal. Calorimetric and optical measurements, reproducible on heating and cooling, demonstrate that the resulting soft nanocomposite exhibits an increased blue phase temperature stability range for a minute concentration of dispersed graphene. The impact is stronger on the ordered, cubic structured blue phase I. These findings suggest that anisotropic nanoparticles may be of great usefulness for stabilizing blue phases.
All-printed and transparent single walled carbon nanotube thin film transistor devices
Authors: Sajed Farzam , Rutherglen Christopher
Published: October 2013

We present fully transparent single-walled all-carbon nanotube thin film transistors (SWCNT TFT) fabricated using low-cost inkjet printing methods. Such a demonstration provides a platform towards low cost fully printed transparent electronics. The SWCNT TFTs were printed with metallic and semiconducting SWCNT using a room temperature printing process, without the requirement of expensive cleanroom facilities. The unoptimized SWCNT TFTs fabricated exhibited an Ion/off ratio of 92 and mobility of 2.27 cm2V−1s−1 and transmissivity of 82%. The combination of both high electrical performance and high transparency make all-SWCNT TFTs desirable for next generation transparent display backplanes and products such as Google Glass.
The effect of system boundaries on the mean free path for confined gases
Authors: Prabha Sooraj K. , D. Sreehari P. , Gopal M. Murali , Sathian Sarith P.
Published: October 2013

The mean free path of rarefied gases is accurately determined using Molecular Dynamics simulations. The simulations are carried out on isothermal argon gas (Lennard-Jones fluid) over a range of rarefaction levels under various confinements (unbounded gas, parallel reflective wall and explicit solid platinum wall bounded gas) in a nanoscale domain. The system is also analyzed independently in constitutive sub-systems to calculate the corresponding local mean free paths. Our studies which predominate in the transition regime substantiate the boundary limiting effect on mean free paths owing to the sharp diminution in molecular free paths near the planar boundaries. These studies provide insight to the transport phenomena of rarefied gases through nanochannels which have established their potential in microscale and nanoscale heat transfer applications.
Piezoelectric strain coefficients in La3Ga5.3Ta0.5Al0.2O14 and Ca3TaGa3Si2O14 crystals
Authors: Irzhak Dmitry , Roshchupkin Dmitry
Published: October 2013

Independent piezoelectric strain coefficients d11 and d14 in disordered La3Ga5.3Ta0.5Al0.2O14 (LGTA) and ordered Ca3TaGa3Si2O14 (CTGS) crystals of the langasite family were measured by high-resolution X-ray diffraction (HRXRD) under external electric field application which causes changes in the interplanar spacing because of the reverse piezoelectric effect. The experiment showed that the piezoelectric strain coefficients can be precisely determined by measuring changes in the interplanar spacing using the optical scheme of a triple-axis X-ray diffractometer. The measured independent piezoelectric strain coefficients d11 and d14 for LGTA and CTGS crystals are d11(LGTA) = 6.455 × 10−12 C/N, d14(LGTA) = −5.117 × 10−12 C/N; d11(CTGS) = 3.330 × 10−12 C/N, d14(CTGS) = −15.835 × 10−12 C/N.
Summer-active perennials in pasture systems improve seasonal pasture distribution without compromising winter-spring production
Authors: Ward G. N. , Clark S. G. , Kearney G. A. , McCaskill M. R. , Raeside M. C. , Lawson A. R. , Behrendt R.
Published: October 2013

Improved dryland pastures for sheep and beef cattle production in south-western Victoria are typically based on summer-dormant cultivars of perennial ryegrass (Lolium perenne L.) or phalaris (Phalaris aquatica L.). These are highly productive in spring but exhibit low accumulation rates over summer–autumn. Summer-active perennial pasture species could potentially alleviate this summer–autumn feed gap. Three pasture systems that used different pastures on each of the three landscape classes (crest, slope, and valley floor) were compared over 4 years. The perennial ryegrass system (henceforth Ryegrass) had a different ryegrass cultivar on each landscape class. The Triple system used lucerne (Medicago sativa L.) (crest), perennial ryegrass (slope), and summer-active tall fescue (Lolium arundinaceum (Schreb) Darbysh.) (valley floor). The Novel system used chicory (Cichorium intybus L.) (crest), Italian ryegrass (Lolium multiflorum Lam.) or hybrid ryegrass (L. × boucheanum Kunth.) (slope), and kikuyu (Pennisetum clandestinum Hochst. ex Chiov.) (valley floor). The pastures were grazed by either one (in the case of the Novel system) or three (in the case of the Ryegrass and Triple systems) animal systems that varied over the life of the experiment. Total annual herbage accumulation of the Ryegrass and Triple systems did not differ. The Novel system consistently had lower total annual dry matter accumulation than the other two systems. Lucerne pastures generally had the highest accumulation rates over summer, followed by the chicory pastures. The kikuyu pastures responded well to summer rainfall but otherwise had similar accumulation rates to the perennial ryegrass and tall fescue pastures over summer. Tall fescue pastures grew well in autumn following wet summers. In spring the perennial ryegrass pastures based on Fitzroy or Avalon were highly productive but seldom grew faster than other pastures. The results support the hypothesis that incorporating deep-rooted, summer-active perennial species will increase pasture production over summer–autumn compared with conventional pasture systems but not at the expense of winter–spring production.