bluuebunny/crossref_metadata_2025 huggingface dataset:
Renal Transplant Complications: Diagnostic and Therapeutic Role of Radiology
Authors: Inci Mehmet Fatih , Ozkan Fuat , See Teik Choon , Tatli Servet
Published: December 2013

Kidney was the first and is the most frequently transplanted organ. Despite improved surgical techniques and transplantation technology, complications do occur and, if left untreated, may lead to catastrophic consequences. Renal transplantation complications may be vascular (eg, renal artery and vein stenosis and thrombosis, arteriovenous fistula, and pseudoaneurysms); urologic (eg, urinary obstruction and leak, and peritransplantation fluid collections, including hematoma, seroma, lymphocele, and abscess formation); and nephrogenic, including acute tubular necrosis, graft rejection, chronic allograft nephropathy, and neoplasm. Early diagnosis and treatment of these complications are paramount to prevent graft failure and other significant morbidities to the patients. Radiology plays a pivotal role in the diagnosis and treatment of these complications, with minimally invasive percutaneous techniques. In this article, we reviewed renal transplantation anatomy, a wide range of complications that may occur after renal transplantation surgery, typical imaging appearances of the complications on varies imaging modalities, and percutaneous interventional techniques that are used in their treatment.
Imaging Features of Carcinoid Heart Disease
Authors: Bradette Simon , Papas Konstantin , Pressacco Josephine
Published: December 2013

This article reviews the basic and clinical features of heart disease associated with carcinoid syndrome, with an emphasis on its principal imaging modalities.
Shared genetic factors influence risk for bipolar disorder and alcohol use disorders
Authors: Carmiol N. , Peralta J.M. , Almasy L. , Contreras J. , Pacheco A. , Escamilla M.A. , Knowles E.E.M. , Raventós H. , Glahn D.C.
Published: December 2013

Bipolar disorder and alcohol use disorder (AUD) have a high rate of comorbidity, more than 50% of individuals with bipolar disorder also receive a diagnosis of AUD in their lifetimes. Although both disorders are heritable, it is unclear if the same genetic factors mediate risk for bipolar disorder and AUD. We examined 733 Costa Rican individuals from 61 bipolar pedigrees. Based on a best estimate process, 32% of the sample met criteria for bipolar disorder, 17% had a lifetime AUD diagnosis, 32% met criteria for lifetime nicotine dependence, and 21% had an anxiety disorder. AUD, nicotine dependence and anxiety disorders were relatively more common among individuals with bipolar disorder than in their non-bipolar relatives. All illnesses were shown to be heritable and bipolar disorder was genetically correlated with AUD, nicotine dependence and anxiety disorders. The genetic correlation between bipolar and AUD remained when controlling for anxiety, suggesting that unique genetic factors influence the risk for comorbid bipolar and AUD independent of anxiety. Our findings provide evidence for shared genetic effects on bipolar disorder and AUD risk. Demonstrating that common genetic factors influence these independent diagnostic constructs could help to refine our diagnostic nosology.
Changes in the perception of mental illness stigma in Germany over the last two decades
Authors: Angermeyer Matthias C. , Matschinger Herbert , Carta Mauro G. , Schomerus Georg
Published: December 2013

Purpose

To examine the evolution of the perception of the stigma attached to mental illness in Germany since 1990 up to the present.

Subjects and methods

Population surveys were conducted in the old German States (former Federal Republic of Germany) in 1990, 2001, and 2011. The perception of stigma attached to people with mental illness was assessed with the help of Link's perceived discrimination and devaluation scale.

Results

In the 2011 survey, less mental illness stigma was perceived by respondents than in the previous surveys. In the eyes of the German public, the devaluation and rejection of people with mental illness has substantially decreased since 1990.

Discussion

The perception of a decline of the stigmatization is in contrast to the development of the German public's attitudes towards persons with mental disorders, which remained unchanged or even worsened.

Conclusion

Perceived and personal attitudes towards persons with mental illness have developed differently, and it remains to be seen whether perceptions of less public stigma will ultimately be followed by improved personal attitudes.
Ketamine-induced antidepressant effects are associated with AMPA receptors-mediated upregulation of mTOR and BDNF in rat hippocampus and prefrontal cortex
Authors: Zhou W. , Wang N. , Yang C. , Li X.-M. , Zhou Z.-Q. , Yang J.-J.
Published: December 2013

Ketamine exerts fast acting, robust, and lasting antidepressant effects in a sub-anesthetic dose, however, the underlying mechanisms are still not fully elucidated. Recent studies have suggested that ketamine's antidepressant effects are probably attributed to the activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. The present study aimed to observe the effects of AMPA receptor modulators on mammalian target of rapamycin (mTOR) and brain-derived neurotrophic factor (BDNF) expression during the procedure of ketamine exerting antidepressant effects. Therefore, we pretreated rats with NBQX, an AMPA receptor antagonist, or CX546, an AMPA receptor agonist, and subsequently observed the immobility time during the forced swimming test (FST) and the hippocampal and prefrontal cortical levels of mTOR and BDNF. The results showed ketamine decreased the immobility time of rats during the FST and increased the hippocampal and prefrontal cortical mTOR and BDNF. NBQX pretreatment significantly increased the immobility time and decreased the levels of mTOR and BDNF when compared with vehicle 1 (DMSO) pretreatment. CX546 pretreatment significantly decreased the immobility time and increased the levels of mTOR and BDNF when compared with vehicle 2 (DMSO + ethanol) pretreatment. Our results suggest ketamine-induced antidepressant effects are associated with AMPA receptors-mediated upregulation of mTOR and BDNF in rat hippocampus and prefrontal cortex.
Quantitation of fibroblast activation protein (FAP)‐specific protease activity in mouse, baboon and human fluids and organs
Authors: Keane Fiona M. , Yao Tsun-Wen , Seelk Stefanie , Gall Margaret G. , Chowdhury Sumaiya , Poplawski Sarah E. , Lai Jack H. , Li Youhua , Wu Wengen , Farrell Penny , Vieira de Ribeiro Ana Julia , Osborne Brenna , Yu Denise M.T. , Seth Devanshi , Rahman Khairunnessa , Haber Paul , Topaloglu A. Kemal , Wang Chuanmin , Thomson Sally , Hennessy Annemarie , Prins John , Twigg Stephen M. , McLennan Susan V. , McCaughan Geoffrey W. , Bachovchin William W. , Gorrell Mark D.
Published: December 2013

The protease fibroblast activation protein (FAP) is a specific marker of activated mesenchymal cells in tumour stroma and fibrotic liver. A specific, reliable FAP enzyme assay has been lacking. FAP's unique and restricted cleavage of the post proline bond was exploited to generate a new specific substrate to quantify FAP enzyme activity. This sensitive assay detected no FAP activity in any tissue or fluid of FAP gene knockout mice, thus confirming assay specificity. Circulating FAP activity was ∼20‐ and 1.3‐fold less in baboon than in mouse and human plasma, respectively. Serum and plasma contained comparable FAP activity. In mice, the highest levels of FAP activity were in uterus, pancreas, submaxillary gland and skin, whereas the lowest levels were in brain, prostate, leukocytes and testis. Baboon organs high in FAP activity included skin, epididymis, bladder, colon, adipose tissue, nerve and tongue. FAP activity was greatly elevated in tumours and associated lymph nodes and in fungal‐infected skin of unhealthy baboons. FAP activity was 14‐ to 18‐fold greater in cirrhotic than in non‐diseased human liver, and circulating FAP activity was almost doubled in alcoholic cirrhosis. Parallel DPP4 measurements concorded with the literature, except for the novel finding of high DPP4 activity in bile. The new FAP enzyme assay is the first to be thoroughly characterised and shows that FAP activity is measurable in most organs and at high levels in some. This new assay is a robust tool for specific quantitation of FAP enzyme activity in both preclinical and clinical samples, particularly liver fibrosis.
GOSIP in Cyberspace: Conceptualization and Scale Development for General Online Social Interaction Propensity
Authors: Blazevic Vera , Wiertz Caroline , Cotte June , De Ruyter Ko , Keeling Debbie Isobel
Published: December 2013

The interactive nature of the Internet has boosted online communication for both social and business purposes. However, individual consumers differ in their predisposition to interact online with others. Whereas an impressive stream of research has investigated media interactivity, the existence of individual differences in the use of different online media, that is, differences in general online social interaction propensity, has so far received less research attention. An individual's predisposition to interact online affects many important consumer behaviors, such as online engagement and participation. Thus, in this paper, we propose and conceptualize general online social interaction propensity as a trait-based individual difference that captures the differences between consumers in their predisposition to interact with others in an online environment. Based on eight studies, we develop and validate a scale for measuring general online social interaction propensity and demonstrate its usefulness in understanding diversity in levels of engagement and in predicting online interaction behaviors.
The Shifting Range of Optimal Web Site Complexity
Authors: Mai Robert , Hoffmann Stefan , Schwarz Uta , Niemand Thomas , Seidel Jana
Published: December 2013

Web designers and providers are keenly interested in determining the ideal range of Web site complexity to facilitate user–Web site interactions. Previous empirical findings have sparked a lively debate about whether Web site complexity inhibits or enhances user responses toward the Web site. This paper develops a theoretical framework that posits that complexity effects shift along a sequence of evaluation criteria depending on the overall intensity and type of Web site complexity. The first experimental study confirms the suggested interaction effect of the overall degree of complexity and the sequence of evaluation criteria: the optimum is lower for upstream criteria (e.g., ease of navigation) and higher for downstream criteria (e.g., attitude toward the Web site). The second experiment distinguishes two dimensions of complexity (structural vs. visual) that evoke the antipodal effects underlying the shift in the optimal range of complexity. The paper also outlines avenues for further research and implications for marketing practitioners.
Inorganic arsenic trioxide induces gap junction loss in association with the downregulation of connexin43 and E‐cadherin in rat hepatic “stem‐like” cells
Authors: Hsiao Pi‐Jung , Jao Jo‐Chi , Tsai Jin‐Lian , Chang Wen‐Tsan , Jeng Kuo‐Shyang , Kuo Kung‐Kai
Published: December 2013

Chronic exposure to inorganic arsenic trioxide causes tumors of the skin, urinary bladder, lung, and liver. Several cancer initiators and promoters have been shown to alter cell–cell signaling by interference with gap junction intercellular communication (GJIC) and/or modulation of cell adhesion molecules, such as connexin43 (Cx43), E‐cadherin, and β‐catenin. The aim of this study was to determine whether the disruption of cell–cell interactions occurs in liver epithelial cells after exposure to arsenic trioxide. WB‐F344 cells were treated with arsenic trioxide (6.25–50 μM) for up to 8 hours, and gap junction function was analyzed using the scrape‐load/dye transfer assay. In addition, the changes in mRNA and protein levels of Cx43, E‐cadherin, and β‐catenin were determined. A significant dose‐ and time‐dependent decrease in GJIC was observed when WB‐F344 cells were exposed to arsenic trioxide (p < 0.05). Consistent with the inhibition of GJIC, cells' exposure to arsenic trioxide resulted in dose‐ and time‐dependent decreases in Cx43 and E‐cadherin mRNA expression and protein levels. However, arsenic trioxide did not alter the mRNA or protein levels of β‐catenin. In an immunofluorescence study, nuclei were heavily stained with anti‐β‐catenin antibody, indicating significant nuclear translocation. In this study, we also demonstrated that arsenic trioxide‐induced GJIC loss was a reversible process. Taken together, these data support the hypothesis that disruption of cell–cell communication may contribute to the tumor‐promoting effect of inorganic arsenic trioxide.
Remote intrathecal morphine preconditioning is ineffective in the presence of neuraxial blockade with lidocaine
Authors: Lu Yao , Wong Gordon Tin Chun , Zhang Ye , Hu Jun , Dong Chunshan
Published: December 2013

Remote intrathecal morphine preconditioning (RMPC) induces cardioprotection via a neural pathway. Intrathecal lidocaine (LID) blocks spinal cord nerve transmission. This study examine whether LID prevents the effects of RMPC. Anesthetized, open chest, male Sprague‐Dawley rats were assigned to one of seven treatment groups 3 days after intrathecal catheter placement. Rats from both RMPC and LID groups, respectively, received intrathecal morphine (3 μg/kg) and lidocaine (1%, 10 μL); morphine was administered by three cycles of 5‐minute infusions interspersed with 5‐minute infusion‐free periods. The LID + RMPC group received the combination of LID and RMPC. Intrathecal naloxone methiodide (NM) (20 μg/kg) was administered either 15 minutes before RMPC, or 5 minutes before LID + RMPC. Ischemia and reperfusion injury were then induced by 30 minutes of left coronary artery occlusion, followed by 120 minutes of reperfusion. Infarct size, as a percentage of the area at risk (AAR), was determined by 2,3,5‐triphenyltetrazolium staining. The RMPC and LID groups markedly reduced the infarct size (IS) compared with controls. LID prevented the effect of RMPC. NM had no effect on control and LID + RMPC treatments. However, NM pretreatment reversed cardioprotection of RMPC treatment. Intrathecal morphine preconditioning is ineffective in the presence of neuraxial blockade with lidocaine.
Miniscrew implant applications in contemporary orthodontics
Authors: Chang Hong‐Po , Tseng Yu‐Chuan
Published: December 2013

The need for orthodontic treatment modalities that provide maximal anchorage control but with minimal patient compliance requirements has led to the development of implant‐assisted orthodontics and dentofacial orthopedics. Skeletal anchorage with miniscrew implants has no patient compliance requirements and has been widely incorporated in orthodontic practice. Miniscrew implants are now routinely used as anchorage devices in orthodontic treatment. This review summarizes recent data regarding the interpretation of bone data (i.e., bone quantity and quality) obtained by preoperative diagnostic computed tomography (CT) or by cone‐beam computed tomography (CBCT) prior to miniscrew implant placement. Such data are essential when selecting appropriate sites for miniscrew implant placement. Bone characteristics that are indications and contraindications for treatment with miniscrew implants are discussed. Additionally, bicortical orthodontic skeletal anchorage, risks associated with miniscrew implant failure, and miniscrew implants for nonsurgical correction of occlusal cant or vertical excess are reviewed. Finally, implant stability is compared between titanium alloy and stainless steel miniscrew implants.
Racial Disparities in Cardiac Rehabilitation Initiation and the Effect on Survival
Authors: Prince David Z. , Sobolev Maria , Gao Ju , Taub Cynthia C.
Published: December 2013

Objectives

To examine predictors of initiation and adherence, identify racial disparities, and compare the survival benefit of cardiac rehabilitation between a white and a unique predominantly non‐white minority in an urban environment.

Design

A retrospective cohort study.

Setting

The outpatient cardiac rehabilitation program at Montefiore Medical Center, Bronx, New York.

Patients

Consecutive patients (n = 822) referred to outpatient cardiac rehabilitation were evaluated.

Methods

Baseline characteristics and outcomes were ascertained from medical records. Multivariate logistic regression was used to examine the association among initiation, age, gender, race, reason for referral, and copayment. Kaplan‐Meier analysis was performed to evaluate mortality outcomes.

Main Outcome Measurements

Racial disparities in rates of initiation, adherence and completion, and survival benefit associated with cardiac rehabilitation.

Results

Among 822 patients referred (51.5% non‐white minorities, 61.1% male), 59.4% initiated cardiac rehabilitation. Non‐white minorities initiated cardiac rehabilitation less often than did white patients (54.4% versus 65.2%, P = .003). After adjustment, white patients were 77.5% more likely to initiate cardiac rehabilitation (odds ratio 1.78; 95% confidence interval 1.13‐2.80). Both white populations and non‐white minorities who participated in cardiac rehabilitation had a lower risk of death (P = .0022).

Conclusions

In a predominantly minority population, racial disparities exist among cardiac rehabilitation participants. Minorities were less likely to initiate cardiac rehabilitation. Gender, referral patterns, and the presence of copayment did not influence initiation. Cardiac rehabilitation initiation was associated with decreased mortality.
Metastatic adenocarcinoma of the mandibular condyle from uterine cervix: Report of a case
Authors: Sugiyama Goro , Ohyama Yukiko , Kiyoshima Tamotsu , Shimizu Mayumi , Kaneki Eisuke , Takenoshita Yasuharu
Published: December 2013

Metastasis to the mandibular condyle is rare, and such lesions should be identified by both clinical and pathological examinations. We experienced a case of adenocarcinoma occurring in the right mandibular condyle. A 65‐year‐old female with uterine cervical cancer showed condylar dysfunction. Imaging examinations revealed a tumor with bone destruction and a rapidly progressive course, while pathological examinations suggested metastasis originating from another site. Based on the clinical and pathological findings, the patient was diagnosed with condylar metastasis derived from the uterine cervix, in addition to a recurrence of uterine cervical cancer.
The effects of Cu doping on crystalline structure and magnetic properties of SmCo5-xCux thin films grown on Ru (0002)
Authors: Yin S. Q. , Wang H. , Zhao H. B. , Jiang Y. , Wang J. P.
Published: December 2013

In this study, we successfully utilized Ru (0002) textured film as underlayer for epitaxial growth of the highly (0001) textured SmCo5-xCux thin films with perpendicular anisotropy. Effects of Cu doping on the crystalline structure and magnetic properties of SmCo5-xCux thin films were investigated. With the increase of the Cu proportion, the Curie temperature (TC) of SmCo5-xCux thin films is largely decreased. The ultra-high anisotropy and adjustable TC indicate that Sm(Co,Cu)5 magnetic film, which is thermally stable at room temperature and writable at an appropriate high temperature, could be a potential choice of heat assisted magnetic recording media materials.
Experimental verification of substrate-induced bianisotropy in optical metamaterials
Authors: Yun Seokho , Hao Jiang Zhi , Ma Ding , Liu Zhiwen , Werner Douglas H. , Mayer Theresa S.
Published: December 2013

This paper reports on substrate-induced bianisotropy in an impedance-matched near-zero-index metallodielectric fishnet nanostructure with vertical sidewalls and a supporting substrate. The effect of bianisotropy on the metamaterial optical properties is confirmed through spectral holography measurements and full-wave electromagnetic simulations, showing asymmetric reflection coefficients from opposite sides of the structure at normal incidence. The non-zero magnetoelectric coupling parameter causes a 0.03 μm shift in the near-infrared zero-index band centered at 1.5 μm and a 38% reduction in transmitted power. The substrate-induced bianisotropy is due to the excitation of an anti-symmetric plasmonic resonance mode identified by comparing simulations of the current distributions on free-standing and substrate-mounted fishnet structures. This experimental demonstration of substrate-induced bianisotropy verifies the previously proposed theory and provides valuable guidance for future plasmonic and metamaterial nanostructures that include substrates.
Strain on field effect transistors with single–walled–carbon nanotube network on flexible substrate
Authors: Kim T. G. , Kim U. J. , Hwang J. S. , Lee E. H. , Hwang S. W. , Kim S.
Published: December 2013

We have systematically analyzed the effect of strain on the electrical properties of flexible field effect transistors with a single-walled carbon nanotube (SWCNT) network on a polyethersulfone substrate. The strain was applied and estimated at the microscopic scale (<1 μm) by using scanning electron microscope (SEM) equipped with indigenously designed special bending jig. Interestingly, the strain estimated at the microscopic scale was found to be significantly different from the strain calculated at the macroscopic scale (centimeter-scale), by a factor of up to 4. Further in-depth analysis using SEM indicated that the significant difference in strain, obtained from two different measurement scales (microscale and macroscale), could be attributed to the formation of cracks and tears in the SWCNT network, or at the junction of SWCNT network and electrode during the strain process. Due to this irreversible morphological change, the electrical properties, such as on current level and field effect mobility, lowered by 14.3% and 4.6%, respectively.
The Stokes-Einstein relation at moderate Schmidt number
Authors: Balboa Usabiaga Florencio , Xie Xiaoyi , Delgado-Buscalioni Rafael , Donev Aleksandar
Published: December 2013

The Stokes-Einstein relation for the self-diffusion coefficient of a spherical particle suspended in an incompressible fluid is an asymptotic result in the limit of large Schmidt number, that is, when momentum diffuses much faster than the particle. When the Schmidt number is moderate, which happens in most particle methods for hydrodynamics, deviations from the Stokes-Einstein prediction are expected. We study these corrections computationally using a recently developed minimally resolved method for coupling particles to an incompressible fluctuating fluid in both two and three dimensions. We find that for moderate Schmidt numbers the diffusion coefficient is reduced relative to the Stokes-Einstein prediction by an amount inversely proportional to the Schmidt number in both two and three dimensions. We find, however, that the Einstein formula is obeyed at all Schmidt numbers, consistent with linear response theory. The mismatch arises because thermal fluctuations affect the drag coefficient for a particle due to the nonlinear nature of the fluid-particle coupling. The numerical data are in good agreement with an approximate self-consistent theory, which can be used to estimate finite-Schmidt number corrections in a variety of methods. Our results indicate that the corrections to the Stokes-Einstein formula come primarily from the fact that the particle itself diffuses together with the momentum. Our study separates effects coming from corrections to no-slip hydrodynamics from those of finite separation of time scales, allowing for a better understanding of widely observed deviations from the Stokes-Einstein prediction in particle methods such as molecular dynamics.
Electronic excitations of bulk LiCl from many-body perturbation theory
Authors: Jiang Yun-Feng , Wang Neng-Ping , Rohlfing Michael
Published: December 2013

We present the quasiparticle band structure and the optical excitation spectrum of bulk LiCl, using many-body perturbation theory. Density-functional theory is used to calculate the ground-state geometry of the system. The quasiparticle band structure is calculated within the GW approximation. Taking the electron-hole interaction into consideration, electron-hole pair states and optical excitations are obtained by solving the Bethe-Salpeter equation for the electron-hole two-particle Green function. The calculated band gap is 9.5 eV, which is in good agreement with the experimental result of 9.4 eV. And the calculated optical absorption spectrum, which contains an exciton peak at 8.8 eV and a resonant-exciton peak at 9.8 eV, is also in good agreement with experimental data.
Fabricating metal-oxide-semiconductor field-effect transistors on a polyethylene terephthalate substrate by applying low-temperature layer transfer of a single-crystalline silicon layer by meniscus force
Authors: Sakaike Kohei , Akazawa Muneki , Nakamura Shogo , Higashi Seiichiro
Published: December 2013

A low-temperature local-layer technique for transferring a single-crystalline silicon (c-Si) film by using a meniscus force was proposed, and an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) was fabricated on polyethylene terephthalate (PET) substrate. It was demonstrated that it is possible to transfer and form c-Si films in the required shape at the required position on PET substrates at extremely low temperatures by utilizing a meniscus force. The proposed technique for layer transfer was applied for fabricating high-performance c-Si MOSFETs on a PET substrate. The fabricated MOSFET showed a high on/off ratio of more than 108 and a high field-effect mobility of 609 cm2 V−1 s−1.
Magnetism, half-metallicity and electrical transport properties of V- and Cr-doped semiconductor SnTe: A theoretical study
Authors: Liu Y. , Bose S. K. , Kudrnovský J.
Published: December 2013

This work presents results for the electronic structure, magnetic properties, and electrical resistivity of the semiconductor SnTe doped with 3d transition metals V and Cr. From the standpoint of potential application in spintronics, we look for half-metallic states and analyze their properties in both rock salt and zinc blende structures using ab initio electronic structure methods. In both cases, it is the Sn-sublattice that is doped with the transition metals, as has been the case with experiments performed so far. We find four half-metallic compounds at their optimized cell volumes. Results of exchange interactions and the Curie temperature are presented and analyzed for all the relevant cases. Resistivity calculation based on Kubo-Greenwood formalism shows that the resistivities of these alloys due to transition metal doping of the Sn-sublattice may vary, in most cases, from typical liquid metal or metallic glass value to 2–3 times higher. 25% V-doping of the Sn-sublattice in the rock salt structure gives a very high resistivity, which can be traced to high values of the lattice parameter resulting in drastically reduced hopping or diffusivity of the states at the Fermi level.
Possible surface antiferromagnetism and no evidence for intergranular tunneling magnetoresistance in La0.5Sr0.5CoO3–δ cobaltites
Authors: Troyanchuk I. O. , Bushinsky M. V. , Lobanovsky L. S.
Published: December 2013

The magnetization and magnetoresistance (MR) of La0.5Sr0.5CoO3–δ have been studied as function of surface/volume ratio and oxygen deficit. All the samples have positive and negative components of MR at low temperature. The small positive component is predominated in low field regime below and well above the coercive field. The positive MR under magnetic moment reorientation is in contradiction with scenario of negative intergranular tunneling magnetoresistance being the hallmark of half-metallic polycrystalline oxides. The oxygen deficit leads to a gradual stabilization of antiferromagnetic phase in bulk and concomitant enhancement of the MR. The decrease in value of magnetization and enhancement of the negative MR component in compacted at high pressure/room temperature powder with a large surface/volume ratio can be ascribed to antiferromagnetism at the surface.
Low-energy D+ and H+ ion irradiation effects on highly oriented pyrolytic graphite
Authors: Kue Park Jun , Won Lee Kyu , Hee Han Jun , Jung Kweon Jin , Kim Dowan , Eui Lee Cheol , Lim Sun-Taek , Kim Gon-Ho , Noh S. J. , Kim H. S.
Published: December 2013

We have investigated the low-energy (100 eV) D+ and H+ ion irradiation effects on the structural and chemical properties of highly oriented pyrolytic graphite (HOPG). Structural disorder due to the ion irradiation was identified by the Raman spectroscopy, the D+ irradiation giving rise to greater structural disorder than the H+ irradiation. Only sp2 bonding was identified in the X-ray photoemission spectroscopy of the D+-irradiated HOPG, indicating no change in the surface chemical structure. The H+ irradiation, on the other hand, gave rise to sp3 bonding and π−π* transition, the sp3 bonding increasing with increasing irradiation dose. It is thus shown that the chemical properties of the HOPG surface may be sensitively modified by the low-energy H+ ion irradiation, but not by the low-energy D+ ion irradiation.
Compositional analysis of GaAs/AlGaAs heterostructures using quantitative scanning transmission electron microscopy
Authors: Kauko H. , Zheng C. L. , Zhu Y. , Glanvill S. , Dwyer C. , Munshi A. M. , Fimland B. O. , van Helvoort A. T. J. , Etheridge J.
Published: December 2013

We demonstrate a method for compositional mapping of AlxGa1–xAs heterostructures with high accuracy and unit cell spatial resolution using quantitative high angle annular dark field scanning transmission electron microscopy. The method is low dose relative to spectroscopic methods and insensitive to the effective source size and higher order lens aberrations. We apply the method to study the spatial variation in Al concentration in cross-sectioned GaAs/AlGaAs core-shell nanowires and quantify the concentration in the Al-rich radial band and the AlGaAs shell segments.
Ultrathin highly uniform Ni(Al) germanosilicide layer with modulated B8 type Ni5(SiGe)3 phase formed on strained Si1−xGex layers
Authors: Liu Linjie , Jin Lei , Knoll Lars , Wirths Stephan , Nichau Alexander , Buca Dan , Mussler Gregor , Holländer Bernhard , Xu Dawei , Feng Di Zeng , Zhang Miao , Zhao Qing-Tai , Mantl Siegfried
Published: December 2013

We present a method to form ultrathin highly uniform Ni(Al) germanosilicide layers on compressively strained Si1−xGex substrates and their structural characteristics. The uniform Ni(Al) germanosilicide film is formed with Ni/Al alloy at an optimized temperature of 400 °C with an optimized Al atomic content of 20 at. %. We find only two kinds of grains in the layer. Both grains show orthogonal relationship with modified B8 type phase. The growth plane is identified to be {10-10}-type plane. After germanosilicidation the strain in the rest Si1−xGex layer is conserved, which provides a great advantage for device application.
Observation of propagating edge spin waves modes
Authors: Lara A. , Metlushko V. , Aliev F. G.
Published: December 2013

Broadband magnetization response of equilateral triangular 1000 nm Permalloy dots has been studied under an in-plane magnetic field, applied parallel (buckle state), and perpendicular (Y state) to the triangles base. Micromagnetic simulations identify edge spin waves (E-SWs) in the buckle state as SWs propagating along the two adjacent edges. These quasi one-dimensional spin waves emitted by the vertex magnetic charges gradually transform from propagating to standing due to interference and are weakly affected by dipolar interdot interaction and variation of the aspect ratio. Spin waves in the Y state have a two dimensional character. These findings open perspectives for implementation of the E-SWs in magnonic crystals and thin films.
Barrier height estimation of asymmetric metal-insulator-metal tunneling diodes
Authors: Cowell E. William , Muir Sean W. , Keszler Douglas A. , Wager John F.
Published: December 2013

A method is developed to estimate barrier heights of an asymmetric metal-insulator-metal (MIM) diode exhibiting Fowler-Nordheim tunneling. The method requires determination of slopes and intercepts of a log(|I(V+Δϕ)2|) versus 1V+Δϕ plot rather than a log(|I(V)2|) versus 1V plot (i.e., a conventional Fowler-Nordheim plot), where I, V, and Δϕ refer to tunneling current, applied voltage, and the difference in barrier heights, respectively. As the value of Δϕ directly impacts the applied electric field magnitude, it is a critical component in barrier height determination from a current-voltage measurement. Conventional Fowler-Nordheim plot analysis does not employ Δϕ, which compromises the accuracy of barrier height estimation when Δϕ≠0. Using the described method, the barrier heights of a ZrCuNiAl/Al2O3/Al MIM diode are estimated to be 1.75 V and 1.07 V, respectively, and the Al2O3 tunneling effective mass is estimated to be 0.47. Additional MIM diodes are analyzed to show that the accuracy of MIM diode barrier height and effective mass estimates is highly sensitive to contamination and/or energy imparted during the deposition of the upper electrode.
Magnetic and elastic anisotropy in magnetorheological elastomers using nickel-based nanoparticles and nanochains
Authors: Landa Romina A. , Soledad Antonel Paula , Ruiz Mariano M. , Perez Oscar E. , Butera Alejandro , Jorge Guillermo , Oliveira Cristiano L. P. , Negri R. Martín
Published: December 2013

Nickel (Ni) based nanoparticles and nanochains were incorporated as fillers in polydimethylsiloxane (PDMS) elastomers and then these mixtures were thermally cured in the presence of a uniform magnetic field. In this way, macroscopically structured-anisotropic PDMS-Ni based magnetorheological composites were obtained with the formation of pseudo-chains-like structures (referred as needles) oriented in the direction of the applied magnetic field when curing. Nanoparticles were synthesized at room temperature, under air ambient atmosphere (open air, atmospheric pressure) and then calcined at 400 °C (in air atmosphere also). The size distribution was obtained by fitting Small Angle X-ray Scattering (SAXS) experiments with a polydisperse hard spheres model and a Schulz-Zimm distribution, obtaining a size distribution centered at (10.0 ± 0.6) nm with polydispersivity given by σ = (8.0 ± 0.2) nm. The SAXS, X-ray powder diffraction, and Transmission Electron Microscope (TEM) experiments are consistent with single crystal nanoparticles of spherical shape (average particle diameter obtained by TEM: (12 ± 1) nm). Nickel-based nanochains (average diameter: 360 nm; average length: 3 μm, obtained by Scanning Electron Microscopy; aspect ratio = length/diameter ∼ 10) were obtained at 85 °C and ambient atmosphere (open air, atmospheric pressure). The magnetic properties of Ni-based nanoparticles and nanochains at room temperature are compared and discussed in terms of surface and size effects. Both Ni-based nanoparticles and nanochains were used as fillers for obtaining the PDMS structured magnetorheological composites, observing the presence of oriented needles. Magnetization curves, ferromagnetic resonance (FMR) spectra, and strain-stress curves of low filler's loading composites (2% w/w of fillers) were determined as functions of the relative orientation with respect to the needles. The results indicate that even at low loadings it is possible to obtain magnetorheological composites with anisotropic properties, with larger anisotropy when using nanochains. For instance, the magnetic remanence, the FMR field, and the elastic response to compression are higher when measured parallel to the needles (about 30% with nanochains as fillers). Analogously, the elastic response is also anisotropic, with larger anisotropy when using nanochains as fillers. Therefore, all experiments performed confirm the high potential of nickel nanochains to induce anisotropic effects in magnetorheological materials.
An opening electromagnetic transducer
Authors: Sun Yanhua , Kang Yihua
Published: December 2013

Tubular solenoids have been widely used without any change since an electrical wire was discovered to create magnetic fields by Hans Christian Oersted in 1820 and thereby the wire was first coiled as a helix into a solenoid coil by William Sturgeon in 1823 and was improved by Joseph Henry in 1829 [see http://www.myetymology.com/encyclopedia/History_of_the_electricity.html; J. M. D. Coey, Magnetism and Magnetic Materials (Cambridge University Press, New York, 2010); and F. Winterberg, Plasma Phys. 8, 541553 (1996)]. A magnetic control method of C-shaped carrying-current wire is proposed, and thereby a new opening electromagnetic transducer evidently differing from the traditional tubular solenoid is created, capable of directly encircling and centering the acted objects in it, bringing about convenient and innovative electromagnetic energy conversion for electromagnetic heating, electromagnetic excitation, physical information capture, and electro-mechanical motion used in science research, industry, and even biomedical activities.
Influence of three classic chromium-based transitions on the behavior of film/substrate interface in diamond-like carbon films
Authors: Yang Xi , Yu Xiang , Wang Yonghui , Shu Wen , Hua Meng
Published: December 2013

Three diamond-like carbon (DLC) films with classic chromium-based transitions containing a typical step-like gradient, a linear gradient and a modulation period, were deposited using a mid-frequency dual-magnetron sputtering system. Studies were performed on samples with almost the same Cr content to compare the interfacial structures and compositions of the three chromium-based transitions, and to investigate the internal stress, adhesion strength, and fracture toughness of the films. The synergistic effect of the transitions deterministically influenced the interfacial properties. The films with a linear gradient had the optimal interfacial properties when compared with the other two films.
Spintronic transport of a non-magnetic molecule between magnetic electrodes
Authors: Kondo Hisashi , Ohno Takahisa
Published: December 2013

The spintronic transport properties of a junction system composed of a non-magnetic molecule sandwiched between ferromagnetic metal electrodes are investigated theoretically using a non-equilibrium Green's function method based on density functional theory. It is revealed that in such a system, the molecular magnetic properties induced by hybridization with the magnetic electrodes play a crucial role. Alignment of the induced molecular spin-split levels is strongly related to the spin injection and tunneling magneto-resistance effects. It is found that in the system with weaker molecule-electrode interaction, stronger spintronic effects of the spin injection and tunneling magneto-resistance are observed.
Laser-induced short-range disorder in aluminum revealed by ultrafast electron diffuse scattering
Authors: Zhu Pengfei , Chen Jie , Li Runze , Chen Long , Cao Jianming , Sheng Zhengming , Zhang Jie
Published: December 2013

We report ultrafast electron diffuse scattering intensity (DSI) measurement in order to study the structural response of aluminum to femtosecond laser excitation. In this measurement, the evolutions of DSI and Bragg peak intensities after the laser excitation are measured and compared in the time domain. Their differences suggest that two kinds of lattice disorder, short-range and long-range, are triggered simultaneously. The former, induced by electron excitation, arises and decays with a faster rate than the latter which is subject to lattice heating. The results presented show that the time-resolved DSI measurements provide complementary insights to the ultrafast diffraction measurements.
Coupled phase transformations and plastic flows under torsion at high pressure in rotational diamond anvil cell: Effect of contact sliding
Authors: Feng Biao , Levitas Valery I.
Published: December 2013

A three-dimensional large-sliding contact model coupled with strain-induced phase transformations (PTs) and plastic flow in a disk-like sample under torsion at high pressure in rotational diamond anvil cell (RDAC) is formulated and studied. Coulomb and plastic friction are combined and take into account variable parameters due to PT. Results are obtained for weaker, equal-strength, and stronger high pressure phases, and for three values of the kinetic coefficient in a strain-controlled kinetic equation and friction coefficient. All drawbacks typical of problem with cohesion are overcome, including eliminating mesh-dependent shear band and artificial plastic zones. Contact sliding intensifies radial plastic flow, which leads to larger reduction in sample thickness. Larger plastic strain and increased pressure in the central region lead to intensification of PT. However, the effect of the reduction in the friction coefficient on PT kinetics is nonmonotonous. Sliding increases away from the center and with growing rotation and is weakly dependent on the kinetic coefficient. Also, cyclic back and forth torsion is studied and compared to unidirectional torsion. Multiple experimental phenomena, e.g., pressure self-multiplication effect, steps (plateaus) at pressure distribution, flow to the center of a sample, and oscillatory pressure distribution for weaker high-pressure phase, are reproduced and interpreted. Reverse PT in high pressure phase that flowed to the low pressure region is revealed. Possible misinterpretation of experimental PT pressure is found. Obtained results represent essential progress toward understanding of strain-induced PTs under compression and shear in RDAC and may be used for designing experiments for synthesis of new high pressure phases and reduction in PT pressure for known phases, as well as for determination of PT kinetics from experiments.
Composition dependence of the mercury vacancies energy levels in HgCdTe: Evolution of the “negative-U” property
Authors: Gemain F. , Robin I. C. , Feuillet G.
Published: December 2013

HgCdTe films grown by liquid phase epitaxy with different Cd compositions were post-annealed to control the Hg vacancy concentration. Then temperature-dependent Hall measurements and photoluminescence measurements allowed us to study the evolution of the Hg vacancy acceptor levels with the cadmium composition. For Cd compositions below 33% the Hg vacancies in HgCdTe present a negative-U property with the ionized state V− stabilized compared to the neutral state V0. For Cd compositions higher than 45%, the Hg vacancies in HgCdTe present a more standard level ordering with the ionized state V− at higher energy than the neutral state V0.
Influence of band gradients on Cu(In,Ga)Se2 solar cell diode factors
Authors: Orgis Thomas , Maiberg Matthias , Scheer Roland
Published: December 2013

The influence of band gap gradients on the charge collection and diode quality factor of solar cells is investigated by device simulation. A back surface band gap gradient manifested as a gradient of the conduction band is found to lead to an increased diode quality factor. Thus, the positive influence of the gradient on the fill factor is partially counterbalanced by the diode quality factor increase. The reason for the latter is the enhanced contribution of space charge region recombination. If the cell is equipped with a double gradient at front and back surfaces, the detrimental diode factor increase can be suppressed. The relevance of the findings is investigated using different carrier lifetimes and doping levels.
Pressure-induced amorphous-to-amorphous reversible transformation in Pr75Al25
Authors: Lin C. L. , Ahmad A. S. , Lou H. B. , Wang X. D. , Cao Q. P. , Li Y. C. , Liu J. , Hu T. D. , Zhang D. X. , Jiang J. Z.
Published: December 2013

A pressure-induced amorphous-to-amorphous reversible transformation was revealed in Pr75Al25 metallic glass (MG) using in situ high-pressure synchrotron x-ray diffraction technique. The transition began at about 21 GPa with a ∼ 5% volume collapse and ended at about 35 GPa. This transition is reversible with hysteresis. Based on the high-pressure behaviors of Ce-based metallic glasses and Pr metal here, we suggest that the pressure-induced polyamorphic transition in Pr75Al25 MG stems from 4f-electron delocalization of Pr metal which leads to abrupt change in bond shortening. These results obtained here provide new insights into the underlying mechanism of the amorphous-to-amorphous phase transition in metallic glasses and will trigger more theoretical and experimental investigations for such transition.
Luminous efficacy model validation and computation of solar illuminance for different climates of India
Authors: Patil K. N. , Garg S. N. , Kaushik S. C.
Published: December 2013

Three luminous efficacy models namely Perez model, Muneer–Kinghorn model, and Littlefair model have been evaluated against measured solar illuminance and solar irradiance at New Delhi. Both these quantities are measured simultaneously, every half an hour, on a horizontal surface, in clear sky as well as intermittent sky. Among three models, Perez model has been found to perform best, with minimum mean bias error and minimum root mean square error. Experimental results also reveal that diffuse luminous efficacy has higher values as compared to global luminous efficacy and beam luminous efficacy. Further, Perez model has been used to assess daylight availability in summer, winter, and monsoon seasons at six Indian stations: New Delhi, Jodhpur, Pune, Kolkata, Shillong, and Leh, covering all climatic conditions in India. This model is used to obtain hourly values of solar illuminance for both global and diffuse components, in a typical meteorological year for each of the six stations. Analysis also shows that Indian climates have clear or intermittent skies for 60%–80% of day-time in a typical year, revealing immense potential for daylight exploitation for energy conservation. Solar global illuminance level assumes the highest value in summer months of April and May, whereas it becomes lowest in winter month of December. In monsoon season, solar illuminance is around 60–65 klx. It is also found that cumulative frequencies for global illuminance increases linearly with solar illuminance, in the range of 0–100 klx. Cumulative frequency for diffuse illuminance increases exponentially with solar illuminance, in the range of 0–60 klx.
Green cubic GaInN/GaN light-emitting diode on microstructured silicon (100)
Authors: Stark Christoph J. M. , Detchprohm Theeradetch , Lee S. C. , Jiang Y.-B. , Brueck S. R. J. , Wetzel Christian
Published: December 2013

GaInN/GaN light-emitting diodes free of piezoelectric polarization were prepared on standard electronic-grade Si(100) substrates. Micro-stripes of GaN and GaInN/GaN quantum wells in the cubic crystal structure were grown on intersecting {111} planes of microscale V-grooved Si in metal-organic vapor phase epitaxy, covering over 50% of the wafer surface area. Crystal phases were identified in electron back-scattering diffraction. A cross-sectional analysis reveals a cubic structure virtually free of line defects. Electroluminescence over 20 to 100 μA is found fixed at 487 nm (peak), 516 nm (dominant). Such structures therefore should allow higher efficiency, wavelength-stable light emitters throughout the visible spectrum.
Scattering due to Schottky barrier height spatial fluctuation on two dimensional electron gas in AlGaN/GaN high electron mobility transistors
Authors: Li Huijie , Liu Guipeng , Wei Hongyuan , Jiao Chunmei , Wang Jianxia , Zhang Heng , Dong Jin Dong , Feng Yuxia , Yang Shaoyan , Wang Lianshan , Zhu Qinsheng , Wang Zhan-Guo
Published: December 2013

A scattering mechanism related to the Schottky barrier height (SBH) spatial fluctuation of the two dimensional electron gas (2DEG) in AlGaN/GaN heterostructures is presented. We find that the low field mobility is on the order of 104–106 cm2/Vs. The 2DEG transport properties are found to be influenced by both the mobility and 2DEG density variations caused by the SBH fluctuation. Our results indicate that a uniform Schottky contact is highly desired to minimize the influence of SBH inhomogeneity on the device performance.