bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficiency enhancement of semi-transparent sandwich type CH3NH3PbI3 perovskite solar cells with island morphology perovskite film by introduction of polystyrene passivation layer
Authors: Heo Jin Hyuck , Jang Min Hyeok , Lee Min Ho , Han Hye Ji , Kang Man Gu , Lee Myung Lae , Im Sang Hyuk
Published: September 2016

Highly semi-transparent sandwich type CH3NH3PbI3 (MAPbI3) island perovskite solar cells with high efficiency were constructed by introduction of a polystyrene (PS) passivation interlayer.
Understanding and manipulating the intrinsic point defect in α-MgAgSb for higher thermoelectric performance
Authors: Liu Zihang , Geng Huiyuan , Mao Jun , Shuai Jing , He Ran , Wang Chao , Cai Wei , Sui Jiehe , Ren Zhifeng
Published: September 2016

Thorough first-principles calculations reveal that an Ag vacancy is the dominant intrinsic point defect in α-MgAgSb. Point-defect engineering can be realized via rationally controlling the hot press temperature due to the recovery effect.
Association between genetic polymorphisms of interleukins and cerebral infarction risk: a meta-analysis
Authors: Wang Jiantao , Fan Niannian , Deng Yili , Zhu Jie , Mei Jing , Chen Yao , Yang Heng
Published: September 2016

Interleukins (ILs) are the most typical inflammatory and immunoregulatory cytokines. Evidences have shown that polymorphisms in ILs are associated with cerebral infarction risk. However, the results remain inconclusive. The present study was to evaluate the role of ILs polymorphisms in cerebral infarction susceptibility. Relevant case-control studies published between January 2000 and December 2015 were searched and retrieved from the electronic databases of Web of Science, PubMed, Embase and the Chinese Biomedical Database. The odds ratio (OR) with its 95% confidence interval (CI) were employed to calculate the strength of association. A total of 55 articles including 12619 cerebral infarction patients and 14436 controls were screened out. Four ILs (IL-1, IL-6, IL-10 and IL-18) contained nine single nucleotide polymorphisms (SNPs; IL-1α −899C/T, IL-1β −511C/T and IL-1β +3953C/T; IL-6 −174G/C and −572C/G; IL-10 −819C/T and −1082A/G; IL-18 −607C/A and −137G/C). Our result showed that IL-1α −899C/T and IL-18 −607C/A (under all the genetic models), and IL-6 −572C/G (under the allelic model, heterogeneity model and dominant model) were associated with increased the risk of cerebral infarction (P<0.05). Subgroup analysis by ethnicity showed that IL-6 −174G/C polymorphism (under all the five models) and IL-10 −1082A/G polymorphism (under the allelic model and heterologous model) were significantly associated with increased the cerebral infarction risk in Asians. Other genetic polymorphisms were not related with cerebral infarction susceptibility under any genetic models. In conclusion, IL-1α −899C/T, IL-6 −572C/G and IL-18 −607C/A might be risk factors for cerebral infarction development. Further studies with well-designed and large sample size are still required.
Angiotensin type-2 (AT-2)-receptor activation reduces renal fibrosis in cyclosporine nephropathy: evidence for blood pressure independent effect
Authors: Castoldi Giovanna , di Gioia Cira R.T. , Carletti Raffaella , Roma Francesca , Zerbini Gianpaolo , Stella Andrea
Published: September 2016

Compound 21 (C21), selective agonist of angiotensin type-2 (AT-2) receptors, shows anti-inflammatory effects in experimental models of hypertension and nephroprotection in diabetes. The aim of the present study was to evaluate the effects of C21 in cyclosporine nephropathy, which is characterized mainly by tubulo-interstitial fibrosis. Ten days before and during the experimental periods, low-salt diet was administered to Sprague–Dawley rats. Cyclosporine-A (CsA; 15 mg/kg per day, intraperitoneal injection) and CsA plus C21 (0.3 mg/kg per day, intraperitoneal injection) were administered for 1 and 4 weeks. Control groups were left without any treatment. Blood pressure (plethysmographic method) and 24 h urinary albumin excretion were measured once a week. At the end of the experimental protocols, the kidneys were excised for histomorphometric analysis of renal fibrosis and for immunohistochemical evaluation of inflammatory infiltrates and type I and type IV collagen expression. After 1 and 4 weeks, the rats treated with CsA showed a significant increase (P<0.01) in blood pressure, no significant changes in urinary albumin excretion and a significant increase (P<0.01) in glomerular and tubulo-interstitial fibrosis and inflammatory infiltrates as compared with the control rats. Treatment with C21 did not modify the CsA dependent increase of blood pressure, which was higher than in control rats, but after 4 weeks of treatment significantly reduced (P<0.01) glomerular and tubulo-interstitial fibrosis, type 1 collagen expression and macrophage infiltration, as compared with rats treated with cyclosporine. The administration of C21 showed a protective effect on cyclosporine nephropathy, decreasing renal fibrosis and macrophage infiltration. These data suggest that C21 may counteract tubulo-interstitial fibrosis, the most potent predictor of the progression of renal diseases.
Joint Engagement and Early Language in Young Children With Fragile X Syndrome
Authors: Hahn Laura J. , Brady Nancy C. , Fleming Kandace K. , Warren Steven F.
Published: September 2016

Purpose

In this study, we examine joint engagement (JE) in young children with fragile X syndrome (FXS) and its relationship to language abilities and autism spectrum disorder symptomatology at 24 to 36 months (toddler period) and 59 to 68 months (child period).

Method

Participants were 28 children with FXS (24 boys, four girls) and their mothers. Videotaped home observations were conducted during the toddler period and coded for JE. Language abilities were measured at both ages from a developmental assessment, a functional measure, and from a language sample. The Childhood Autism Rating Scale (Schopler, Reichler, & Renner, 1988) was completed at both ages.

Results

Children with FXS spent more time in supported JE than in coordinated JE. Using a weighted JE variable, we found that children with FXS who had higher weighted JE scores also had more advanced expressive language skills at both the toddler and child periods. Weighted JE was negatively related to autism symptomatology in the toddler period.

Conclusion

This study provides evidence that children with FXS who use more JE also have more advanced expressive language skills in early development. Therefore, existing early interventions that target JE behaviors may be effective for promoting language, social communication, and social interaction in this population.

Supplemental Material

https://doi.org/10.23641/asha.14963901
Random Item Generation Is Affected by Age
Authors: Multani Namita , Rudzicz Frank , Wong Wing Yiu Stephanie , Namasivayam Aravind Kumar , van Lieshout Pascal
Published: September 2016

Purpose

Random item generation (RIG) involves central executive functioning. Measuring aspects of random sequences can therefore provide a simple method to complement other tools for cognitive assessment. We examine the extent to which RIG relates to specific measures of cognitive function, and whether those measures can be estimated using RIG only.

Method

Twelve healthy older adults (age:
M
= 70.3 years,
SD
= 4.9; 8 women and 4 men) and 20 healthy young adults (age:
M
= 24 years,
SD
= 4.0; 12 women and 8 men) participated in this pilot study. Each completed a RIG task, along with the color Stroop test, the Repeatable Battery for the Assessment of Neuropsychological Status, and the Peabody Picture Vocabulary Test–Fourth Edition (Dunn & Dunn, 2007). Several statistical features extracted from RIG sequences, including recurrence quantification, were found to be related to the other measures through correlation, regression, and a neural-network model.

Results

The authors found significant effects of age in RIG and demonstrate that nonlinear machine learning can use measures of RIG to accurately predict outcomes from other tools.

Conclusions

These results suggest that RIG can be used as a relatively simple predictor for other tools and in particular seems promising as a potential screening tool for selective attention in healthy aging.

Supplemental Material

https://doi.org/10.23641/asha.14963904
W‐band quasi‐elliptical waveguide filter with cross‐coupling and source–load coupling
Authors: Ding Jiangqiao , Liu Dong , Shi Shengcai , Wu Wen
Published: September 2016

A high‐performance waveguide bandpass filter operating at W‐band is presented. This folded fourth‐order filter with quasi‐elliptic response is developed by introducing cross‐coupling and source–load coupling, while maintaining a compact construction for simple computer numerical control (CNC) milling process. The filter fabricated within aluminium block shows an insertion loss of about 1.2 dB in a 3 dB fractional bandwidth of 5.5% from 90.1 to 95.2 GHz, which are very close to the simulated results in the full W‐band.
Luminescent coverglass for improved absorption efficiency in III–V photovoltaic modules
Authors: Nam W.I. , Kang E.K. , Park H.G. , Jun D.‐H. , Song Y.M.
Published: September 2016

An initial demonstration is reported in terms of maximising performance of photovoltaic modules. Experimental results of a triple junction solar cell covered with a 3 mm red‐emitting luminous glass which can be efficiently excited by ultraviolet light indicate that this combination exhibits significantly enhanced efficiency of 36.5% under one‐sun of AM1.5G. Integrating a luminescent (LSC) glass onto modules without converting any fabrication process at the device level is considered to be one of the predominant advantages of this device. Additionally, in order to achieve strong visible emission, it is mandatory to determine a thickness of LSC coverglass due to the edge reflection.
Computationally‐efficient surrogate‐assisted dimension scaling of compact dual‐band couplers
Authors: Koziel Slawomir , Bekasiewicz Adrian
Published: September 2016

Reusing existing results in order to facilitate optimisation of structures for various sets of performance requirements such as operating frequencies is an attractive concept. When implemented properly, it can lead to considerable speedup of the microwave design process. In general, re‐design of microwave structures is a challenging task, particularly for compact components where considerable electromagnetic (EM) cross‐couplings make the relationships between geometry parameters and the structure responses complex. In this study, the authors address geometry scaling of miniaturised dual‐band couplers by means of inverse surrogate modelling. It allows for fast estimation of the optimum values of structure dimensions corresponding to required operating frequencies, independently for each band. The inverse surrogate is constructed based on a set of reference designs obtained by optimising the equivalent circuit model of the coupler, and subsequently corrected using output space mapping to accommodate the discrepancies between the network model and the EM‐simulation one. As demonstrated using a compact dual‐band microstrip branch‐line coupler example, geometry scaling is possible in a wide range of operating frequencies and at a very low cost of just a single EM simulation of the structure at hand. Numerical results are validated through physical measurements of fabricated coupler prototypes for several test cases.
Tilted‐beam MPA with broad‐useful bandwidth
Authors: Chacko Bybi Puthenkalapurayil , Augustin Gijo , Denidni Tayeb A.
Published: September 2016

A low‐profile, beam tilted microstrip patch antenna (MPA) with broad‐useful bandwidth and improved gain is presented. The proposed design comprises of a rectangular MPA and a square‐loop unit‐cell‐based metasurface superstrate with different effective refractive index regions. The beam tilting is achieved by the phenomenon of phase difference produced by the superstrate having different refractive index regions. The experimental results display a maximum beam tilt of 27° in the E‐plane at 5 GHz with a slight frequency dependability of 0.013°/MHz. The proposed design also offers a broad‐useful bandwidth of 11% centred at 4.82 GHz, while maintaining relatively low antenna height of 0.06λ. Moreover, uniform field distribution due to superstrate provides a maximum gain of 8.4 dBi with a variation ≤1.3 dB.
Decreasing the frequency of HVDC commutation failures caused by harmonics
Authors: Wang Feng , Liu Tian‐qi , Li Xing‐yuan
Published: September 2016

Commutation failure, primarily caused by voltage drops and distortion, may lead to high‐voltage direct current (HVDC) power interruption and AC system oscillation. To date, there have been few studies on the mechanism and prevention of commutation failure based on voltage distortion caused by harmonics. This study analyses the influence of harmonic voltage on commutation failure based on voltage time area and proposes a method for quantitative analysis of harmonic effects. The analysis shows that limiting the DC current is an effective method to mitigate commutation failure caused by harmonics. A voltage distortion‐dependent commutation failure prevention strategy is proposed, and the controller is applied on the inverter side. The selection of parameters is based on the influence of various harmonic orders. The validity and effectiveness of the proposed methods are verified by simulations, which show that voltage distortion‐dependent commutation failure prevention strategy can improve the DC system recovery characteristics and suppress subsequent commutation failure caused by harmonics.
Non‐invasive load monitoring of induction motor drives using magnetic flux sensors
Authors: Liu Zheng , Tian Guiyun , Cao Wenping , Dai Xuewu , Shaw Brian , Lambert Robert
Published: September 2016

Existing load monitoring methods for induction machines are generally effective, but suffer from sensitivity problems at low speeds and non‐linearity problems at high supply frequencies. This study proposes a new non‐invasive load monitoring method based on giant magnetoresistance flux sensors to trace stray flux leaking from induction motors. Finite element analysis is applied to analyse stray flux features of test machines. Contrary to the conventional methods of measuring stator and/or rotator rotor voltage and current, the proposed method measures the dynamic magnetic field at specific locations and provides time‐spectrum features (e.g. spectrograms), response time load and stator/rotor characteristics. Three induction motors with different starting loading profiles are tested at two separate test benches and their results are analysed in the time‐frequency domain. Their steady features and dynamic load response time through spectrograms under variable loads are extracted to correlate with load variations based on spectrogram information. In addition, the transient stray flux spectrogram and time information are more effective for load monitoring than steady state information from numerical and experimental studies. The proposed method is proven to be a low‐cost and non‐invasive method for induction machine load monitoring.
Tibiofemoral Osteoarthritis and Varus–Valgus Laxity
Authors: Freisinger Gregory , Schmitt Laura , Wanamaker Andrea , Siston Robert , Chaudhari Ajit
Published: September 2016

The purpose of this study was to systematically review and synthesize the literature measuring varus–valgus laxity in individuals with tibiofemoral osteoarthritis (OA). Specifically, we aimed to identify varus–valgus laxity differences between persons with OA and controls, by radiographic disease severity, by frontal plane knee alignment, and by sex. We also aimed to identify if there was a relationship between varus–valgus laxity and clinical performance and self-reported function. We systematically searched for peer-reviewed original research articles in PubMed, Scopus, and CINAHL to identify all existing literature regarding knee OA and objective measurement of varus–valgus laxity in vivo. Forty articles were identified that met the inclusion criteria and data were extracted. Varus–valgus laxity was significantly greater in individuals with OA compared with controls in a majority of studies, while no study found laxity to be significantly greater in controls. Varus–valgus laxity of the knee was reported in persons with OA and varying degrees of frontal plane alignment, disease severity, clinical performance, and self-reported function but no consensus finding could be identified. Females with knee OA appear to have more varus–valgus laxity than males. Meta-analysis was not possible due to the heterogeneity of the subject populations and differences in laxity measurement devices, applied loading, and laxity definitions. Increased varus–valgus laxity is a characteristic of knee joints with OA. Large variances exist in reported varus–valgus laxity and may be due to differences in measurement devices. Prospective studies on joint laxity are needed to identify if increased varus–valgus laxity is a causative factor in OA incidence and progression.
The Varus–Valgus Constrained Knee Implant: Survivorship and Outcomes
Authors: Siqueira Marcelo , Jacob Paul , McLaughlin John , Klika Alison , Molloy Robert , Barsoum Wael , Higuera Carlos
Published: September 2016

The purpose of this study was to estimate the survivorship of the varus–valgus constrained (VVC) knee implants in primary, aseptic, and septic revision total knee arthroplasty (TKA); determine functional outcomes; main modes of failure; and variables associated with increased mechanical failures. In this study, 685 consecutive cases of primary (n = 247), aseptic (n = 315), and septic revision (n = 123) TKAs with VVC implants were performed between 1999 and 2008; 533 knees (78%) had a mean follow-up of 8.2 years (range, 2–15.1). Kaplan–Meier method was used to evaluate implant survival with mechanical failure as the end point. Clinical outcomes were measured with a modified Knee Society Score (mKSS) and modified Knee Function Score (mKFS) and modes of failure were determined. Cox proportional hazards models were performed to assess for factors associated with implant failure. Ten-year survival was 88.5% (95% confidence interval [CI]: 83.9–93.5%) for primary TKAs, 75.8% (95% CI: 70.4–81.7%) for aseptic, and 54.6% (95% CI: 43.7–68.2%) for septic revisions. Improvement in pre- to postoperative mKSS and mKFS were significant in all three groups (p < 0.05). The most common mode of failure overall was infection. Mechanical modes of failures included periprosthetic fracture (45%) for primary TKA and soft tissue instability (19%) for aseptic revisions. A longer period since the last surgery in affected knee was associated with lower mechanical failures (hazards ratio of 0.55 [95% CI: 0.31–0.95], p = 0.03). VVC implant showed reliable survivorship at 10 years although careful patient selection is warranted due to the risk of infection. The main mechanical modes of failure were instability and periprosthetic fracture.
Efficacy of β-Tricalcium Phosphate Graft into the Bone Defects after Bone-Patellar Tendon-Bone Anterior Cruciate Ligament Reconstruction
Authors: Kobayashi Atsushi , Ikeda Keiko , Hatayama Kazuhisa , Yanagisawa Sinya , Kato Kazuo , Higuchi Hiroshi
Published: September 2016

This prospective pilot study investigated whether grafting β-tricalcium phosphate (B-TCP) into the bone-patellar tendon-bone (BPTB)-harvesting site after anterior cruciate ligament reconstruction would accelerate bone and tendon regeneration in the grafted site. Overall, 19 patients agreed prospectively to undergo regular morphological and histological examinations of the B-TCP-grafted site. Postoperative radiographic, ultrasonographic, and magnetic resonance imaging (MRI) examinations were performed to evaluate the grafted site at 1, 3, 6, and 12 months. Postoperative knee function and donor-site morbidity were assessed at 12 months using the kneeling test. A histological examination was also performed at this time Radiographic examination and MRI showed that the grafted B-TCP was completely absorbed and remodeled into normal bone structure in the tibia and patella at 6 months postoperatively. Histological and ultrasonographic examinations of all subjects showed that the grafted B-TCP was substituted by normal bone tissue, and the patellar tendon − bone junction had regenerated at 12 months postoperatively. Clinical functional knee tests showed good recovery of the donor site. All patients could perform kneeling and knee walking on hard ground. The results of this pilot study suggest that grafting B-TCP into the BPTB-harvesting site promotes the remodeling process of the bone and patellar tendon structures. This surgical treatment would decrease an incidence of the anterior knee pain after ACLR using a BPTB autograft.
Bayesian modelling of the emission spectrum of the Joint European Torus Lithium Beam Emission Spectroscopy system
Authors: Kwak Sehyun , Svensson J. , Brix M. , Ghim Y.-c. ,   JET Contributors
Published: September 2016

A Bayesian model of the emission spectrum of the JET lithium beam has been developed to infer the intensity of the Li I (2p-2s) line radiation and associated uncertainties. The detected spectrum for each channel of the lithium beam emission spectroscopy system is here modelled by a single Li line modified by an instrumental function, Bremsstrahlung background, instrumental offset, and interference filter curve. Both the instrumental function and the interference filter curve are modelled with non-parametric Gaussian processes. All free parameters of the model, the intensities of the Li line, Bremsstrahlung background, and instrumental offset, are inferred using Bayesian probability theory with a Gaussian likelihood for photon statistics and electronic background noise. The prior distributions of the free parameters are chosen as Gaussians. Given these assumptions, the intensity of the Li line and corresponding uncertainties are analytically available using a Bayesian linear inversion technique. The proposed approach makes it possible to extract the intensity of Li line without doing a separate background subtraction through modulation of the Li beam.
Development of a high resolution x-ray spectrometer for the National Ignition Facility (NIF)
Authors: Hill K. W. , Bitter M. , Delgado-Aparicio L. , Efthimion P. C. , Ellis R. , Gao L. , Maddox J. , Pablant N. A. , Schneider M. B. , Chen H. , Ayers S. , Kauffman R. L. , MacPhee A. G. , Beiersdorfer P. , Bettencourt R. , Ma T. , Nora R. C. , Scott H. A. , Thorn D. B. , Kilkenny J. D. , Nelson D. , Shoup M. , Maron Y.
Published: September 2016

A high resolution (E/ΔE = 1200-1800) Bragg crystal x-ray spectrometer is being developed to measure plasma parameters in National Ignition Facility experiments. The instrument will be a diagnostic instrument manipulator positioned cassette designed mainly to infer electron density in compressed capsules from Stark broadening of the helium-β (1s2-1s3p) lines of krypton and electron temperature from the relative intensities of dielectronic satellites. Two conically shaped crystals will diffract and focus (1) the Kr Heβ complex and (2) the Heα (1s2-1s2p) and Lyα (1s-2p) complexes onto a streak camera photocathode for time resolved measurement, and a third cylindrical or conical crystal will focus the full Heα to Heβ spectral range onto an image plate to provide a time integrated calibration spectrum. Calculations of source x-ray intensity, spectrometer throughput, and spectral resolution are presented. Details of the conical-crystal focusing properties as well as the status of the instrumental design are also presented.
Near-body vorticity dynamics of a square cylinder subjected to an inline pulsatile free stream flow
Authors: Krishnan Hrisheekesh , Agrawal Amit , Sharma Atul , Sheridan John
Published: September 2016

In the present work, the effect of an inflow sinusoidal excitation that is superimposed over the mean flow on the vortex-shedding characteristics of a square cylinder is studied. The frequency of pulsation is varied around the natural vortex-shedding frequency, and the amplitude of pulsation is varied moderately in comparison to the cylinder diameter, at a fixed Reynolds number (=100). A flow regime map is prepared and compared with the experimental results, which are available for a circular cylinder that is subjected to inline excitation. We correlate the spectra to the corresponding flow regime. Visualization of the vorticity contours reveals that the significant interaction of the base-region vorticities with the main shear layer vorticities is important in the mechanism of formation of the several vortex-shedding modes. The strength and sign of base region vorticity with respect to the shear layers has a fundamental role to play in the mechanism of formation. It is hypothesized that the similarity in vortex-shedding modes across different excitation types, bluff body geometry, and for different parameters is due to the similarity in the underlying vorticity dynamics.
Compact ECEI system with in-vessel reflective optics for WEST
Authors: Nam Y. B. , Park H. K. , Lee W. , Yun G. S. , Kim M. , Sabot R. , Elbeze D. , Lotte P. , Shen J.
Published: September 2016

An electron cyclotron emission imaging (ECEI) diagnostic system for WEST (W Environment for Steady state Tokamak) is under development to study the MHD instabilities affected by tungsten impurities. The system will provide 2-D Te fluctuation images (width × height = ∼18 cm × ∼ 34 cm at low field side and ∼13 cm × ∼ 39 cm at high field side) from a poloidal cross section with high spatial (≤1.7 cm) and temporal (≤2 μs) resolutions. While the key concept and electronic structure are similar to that of prior ECEI systems on other tokamak devices such as KSTAR, DIII-D, or ASDEX-U, part of the imaging optics have to be placed inside the vacuum vessel in order to resolve issues on limited installation space and longer beam path to the detector position. The in-vessel optics consisting of two large curvature-radius mirrors are expected to withstand the extreme heating on long-pulse operation scenario (∼1000 s). The out-vessel optical housing is constructed as compact as possible to remove easily from the installation site in case of necessity. Commissioning of the system is scheduled on the second experimental WEST campaign end of 2017.
Tuning vibrational mode localization with frequency windowing
Authors: Cheng Xiaolu , Talbot Justin J. , Steele Ryan P.
Published: September 2016

Local-mode coordinates have previously been shown to be an effective starting point for anharmonic vibrational spectroscopy calculations. This general approach borrows techniques from localized-orbital machinery in electronic structure theory and generates a new set of spatially localized vibrational modes. These modes exhibit a well-behaved spatial decay of anharmonic mode couplings, which, in turn, allows for a systematic, a priori truncation of couplings and increased computational efficiency. Fully localized modes, however, have been found to lead to unintuitive mixtures of characteristic motions, such as stretches and bends, and accordingly large bilinear couplings. In this work, a very simple, tunable localization frequency window is introduced, in order to realize the transition from normal modes to fully localized modes. Partial localization can be achieved by localizing only pairs of modes within this traveling frequency window, which allows for intuitive interpretation of modes. The optimal window size is suggested to be a few hundreds of wave numbers, based on small- to medium-sized test systems, including water clusters and polypeptides. The new sets of partially localized coordinates retain their spatial coupling decay behavior while providing a reduced number of potential energy evaluations for convergence of anharmonic spectra.
Thermoelectric properties of skutterudite CoSb3 thin films
Authors: Daniel M. V. , Lindorf M. , Albrecht M.
Published: September 2016

The thermoelectric properties of Co-Sb thin films with different Sb content and with a thickness of 30 nm were investigated with respect to the composition and the corresponding structural properties of these films. The films were prepared by molecular beam deposition either by codeposition on heated substrates or room temperature deposition followed by a post-annealing step. It was found that the prepared films exhibit bipolar conduction, indicated by a positive Hall constant and a negative Seebeck coefficient. The obtained results can be well explained by using the bipolar model, assuming heavy electrons and light holes, which was finally confirmed experimentally by the preparation of p- and n-type doped CoSb3 thin films. Furthermore, variable range hopping was identified by temperature dependent transport measurements as dominant conduction mechanism at low temperatures.
A comparison of “flat fielding” techniques for x-ray framing cameras
Authors: Benedetti L. R. , Trosseille C. , Holder J. P. , Piston K. , Hargrove D. , Bradley D. K. , Bell P. , Raimbourg J. , Prat M. , Pickworth L. A. , Khan S. F.
Published: September 2016

Gain can vary across the active area of an x-ray framing camera by a factor of 4 (or more!) due to the voltage loss and dispersion associated with pulse transmission in a microstripline-coated microchannel plate. In order to make quantitative measurements, it is consequently important to measure the gain variation (“flat field”). Moreover, because of electromagnetic cross talk, gain variation depends on specific operational parameters, and ideally a flat field would be obtained at all operating conditions. As part of a collaboration between Lawrence Livermore National Laboratory’s National Ignition Facility and the Commissariat à l’Énergie Atomique, we have been able to evaluate the consistency of three different methods of measuring x-ray flat fields. By applying all three methods to a single camera, we are able to isolate performance from method. Here we report the consistency of the methods and discuss systematic issues with the implementation and analysis of each.
Conformation-specific spectroscopy of alkyl benzyl radicals: Effects of a radical center on the CH stretch infrared spectrum of an alkyl chain
Authors: Korn Joseph A. , Tabor Daniel P. , Sibert Edwin L. , Zwier Timothy S.
Published: September 2016

An important initial step in the combustion of gasoline and diesel fuels is the abstraction of hydrogen from alkylbenzenes to form resonance-stabilized alkyl benzyl radicals. This work uses, for the first time, double resonance spectroscopy methods to explore the conformation-specific vibronic and infrared spectroscopy of the α-ethylbenzyl (αEtBz) and α-propylbenzyl (αPrBz) radicals. Local mode Hamiltonian modeling enables assignment of the alkyl CH stretch IR spectra, accounting for Fermi resonance that complicates aliphatic alkyl CH stretch IR spectroscopy. The ground state conformational preferences of the ethyl and propyl chains are changed from those in the alkylbenzenes themselves, with global minima occurring for an in-plane orientation of the alkyl chain (trans) about its first dihedral angle (ϕf123, numbers are alkyl C atoms. C1 is CH radical site). This in-plane structure is the only observed conformer for the α-EtBz radical, while two conformers, tt and tg′ share this orientation at the first dihedral, but differ in the second (ϕ1234) for the αPrBz radical. The in-plane orientation lowers the local site frequencies of the CH2 group stretches immediately adjacent to the benzylic radical site by about 50 cm−1 relative to those in pure alkyl chains or alkylbenzenes. This effect of the radical site is localized on the first CH2 group, with little effect on subsequent members of the alkyl chain. In the D1 excited electronic state, an out-of-plane orientation is preferred for the alkyl chains, leading to torsional mode Franck-Condon activity in the D0-D1 spectra that is both conformer-specific and diagnostic of the conformational change.
Origin of steps in magnetization loops of martensitic Ni-Mn-Ga films on MgO(001)
Authors: Laptev Aleksej , Lebecki Kristof , Welker Gesa , Luo Yuansu , Samwer Konrad , Fonin Mikhail
Published: September 2016

We study the temperature dependent magnetization properties of (010)-oriented Ni-Mn-Ga epitaxial films on MgO(001) substrates. In the martensitic phase, we observe pronounced abrupt slope changes in the magnetization loops for all studied samples. Our experimental findings are discussed in conjunction with the micromagnetic simulations, revealing that the characteristic magnetization behavior is governed solely by the magnetization switching within the specific martensitic variant pattern, and no reorientation of twin variants is involved in the process. Our study emphasizes the important role of the magnetostatic interactions in the magnetization behavior of magnetic shape memory alloy thin films.
A spectroscopic case for SPSi detection: The third-row in a single molecule
Authors: Finney Brian , Fortenberry Ryan C. , Francisco Joseph S. , Peterson Kirk A.
Published: September 2016

In moving beyond the second row of the periodic table for molecules of astronomical and atmospheric significance, the exploration of sulfur and phosphorus chemistry is essential. Additionally, silicon is abundant in most astrophysical environments and is a major component of most rocky bodies. The triatomic molecule composed of each of these atoms is therefore a tantalizing candidate for spectroscopic characterization for astrophysical reasons as well as gaining further understanding into the chemical physics of molecules that are not carbon-based. The current work employs high-level quantum chemical techniques to provide new insights into this simplest of heterogeneous third-row atom systems. The fundamental vibrational frequencies are all within the 350-600 cm−1 range and do not demonstrate strong anharmonicities. These frequencies, rotational constants, vibrationally excited state spectroscopic data, and related isotopic substitution information produced will aid in laboratory experimentation and, even potentially, telescopic observation since modern instruments possess the power to resolve extremely fine details.
Ion-acoustic solitons and vortices in the e-p-i plasma with field-aligned inhomogeneous flow
Authors: Saleem H. , Ali S. , Saeed U. , Haque Q.
Published: September 2016

The linear and nonlinear characteristics of the ion-acoustic waves are studied in a magnetized electron-positron-ion (e-p-i) plasma with shear flow along the ambient magnetic field. The sheared flow reduces or enhances the frequency of the wave strongly depending upon its polarity and nonlinear equations yield stable electrostatic structures in the form of solitons and vortices. Therefore, it is suggested that in the presence of shear flow, the electrostatic fields with real frequency ωr < csk (where cs is the ion sound speed) exist in e-p-i plasmas. Numerical solutions are discussed using the normalized parameters.
Generation of gamma-ray beam with orbital angular momentum in the QED regime
Authors: Liu Chen , Shen Baifei , Zhang Xiaomei , Shi Yin , Ji Liangliang , Wang Wenpeng , Yi Longqing , Zhang Lingang , Xu Tongjun , Pei Zhikun , Xu Zhizhan
Published: September 2016

We propose a scheme to generate high-energy gamma-ray photons with an orbital angular momentum (OAM) from laser-plasma interactions by irradiating a circularly polarized Laguerre–Gaussian laser on a thin plasma target. The spin angular momentum and OAM are first transferred to electrons from the driving laser, and then the OAM is transferred to the gamma-ray photons from the electrons through quantum radiation. This scheme has been demonstrated by using three-dimensional quantum electrodynamics particle-in-cell simulations. The topological charge, chirality, and carrier-envelope phase of the short ultra-intense vortex laser can be revealed according to the energy distribution of gamma-ray emission.
Ultrasonic micro-motor with multilayer piezoelectric ceramic and chamfered driving tips
Authors: Zhao Yanqiang , Yuan Songmei , Chu Xiangcheng , Gao Shuning , Zhong Zuojin , Zhu Cong
Published: September 2016

In this study, an oblate-type ultrasonic micro-motor with multilayer piezoelectric ceramic and chamfered driving tips was proposed and experimentally researched. The micro-motor works based on the standing-wave principle and has a higher rotary speed than the traditional standing-wave one in principle, reaching a rotary speed of 2100 r/min in this study at the voltage of 20 Vp−p. When the micro-motor rotates, single phase alternating current is required, namely, V=Asinωt, and exchanging the signal wire and ground wire will not change the rotary direction of the motor, which reinforces the safety and the compaction of this motor. The ratio of the maximum displacement value of the speed feeding direction and the preload direction is approximately 4, showing a characteristic of high speed and low ability to load.
A reduced order model for dielectric elastomer actuators over a range of frequencies and prestrains
Authors: Kiser Jillian , Manning Michael , Adler David , Breuer Kenneth
Published: September 2016

The actuation strain of an equibiaxially prestrained dielectric elastomer membrane is studied as a function of driving frequency and prestrain. Experimental data are gathered on the membrane's creep and recovery following DC actuation, as well as the steady state amplitude and phase for AC driving voltages ranging from 2 to 40 Hz. The effect of prestretch on steady state actuation was also investigated, using membranes of both 250% and 300% prestretch. A three-element generalized Kelvin-Voigt model is developed to capture the transient and steady-state actuation responses as a function of frequency and prestrain. We show that, despite its relative simplicity, this model captures the relevant timescales for the membrane behavior with good fidelity and can be used to accurately predict the actuation magnitude and phase as a function of time over a range of actuation configurations and driving conditions.
A simple model for estimating a magnetic field in laser-driven coils
Authors: Fiksel Gennady , Fox William , Gao Lan , Ji Hantao
Published: September 2016

Magnetic field generation by laser-driven coils is a promising way of magnetizing plasma in laboratory high-energy-density plasma experiments. A typical configuration consists of two electrodes—one electrode is irradiated with a high-intensity laser beam and another electrode collects charged particles from the expanding plasma. The two electrodes are separated by a narrow gap forming a capacitor-like configuration and are connected with a conducting wire-coil. The charge-separation in the expanding plasma builds up a potential difference between the electrodes that drives the electrical current in the coil. A magnetic field of tens to hundreds of Teslas generated inside the coil has been reported. This paper presents a simple model that estimates the magnetic field using simple assumptions. The results are compared with the published experimental data.
Enhanced thermoelectric performance of n-type transformable AgBiSe2 polymorphs by indium doping
Authors: Liu Xiaocun , Jin Dou , Liang Xin
Published: September 2016

We demonstrate the improved thermoelectric properties of n-type lead-free transformable AgBiSe2 polymorphs by indium doping on silver sites. X-ray diffraction analysis suggests that complete solid solutions are well formed up to [In] = 0.02. Electrical conductivity and Seebeck coefficient behave in a routinely opposite manner due to the dominant role of the carrier concentration adjusted by the localized indium impurity levels, as also suggested by our density functional theory (DFT) calculations. As indium concentration increases, we observe a drastic variation of the thermoelectric transport properties with temperature, in the range of 450 to 580 K. By performing the isothermal electrical measurements, we attribute this interesting behavior to the ongoing α to β phase transformation process. The In 5s lone pair electrons, as indicated from our DFT calculations, increase the anharmonicity of the chemical bonds and enhance the phonon-phonon scattering. This, together with the introduced InAg.. point defects, further brings down the lattice thermal conductivity. The maximum thermoelectric figure of merit ZT is achieved at 773 K and increases from 0.3 for pristine AgBiSe2 to 0.7 for an optimal [In] = 0.015 doping, a more than two times enhancement.
Domain wall orientation and domain shape in KTiOPO4 crystals
Authors: Shur V. Ya. , Vaskina E. M. , Pelegova E. V. , Chuvakova M. A. , Akhmatkhanov A. R. , Kizko O. V. , Ivanov M. , Kholkin A. L.
Published: September 2016

Domain shape evolution and domain wall motion have been studied in KTiOPO4 (KTP) ferroelectric single crystals using complementary experimental methods. The in situ visualization of domain kinetics has allowed revealing: (1) qualitative change of the domain shape, (2) dependence of the domain wall velocity on its orientation, (3) jump-like domain wall motion caused by domain merging, (4) effect of domain shape stability. The model of domain wall motion driven by generation of elementary steps (kink-pair nucleation) and subsequent kink motion is presented. The decrease in the relative velocity of the approaching parallel domain walls is attributed to electrostatic interaction. The effect of polarization reversal induced by chemical etching is observed. The obtained results are important for the development of domain engineering in the crystals of KTP family.
Micro-electromechanical memory bit based on magnetic repulsion
Authors: López-Suárez Miquel , Neri Igor
Published: September 2016

A bistable micro-mechanical system based on magnetic repulsion is presented exploring its applicability as memory unit where the state of the bit is encoded in the rest position of a deflected cantilever. The non-linearity induced on the cantilever can be tuned through the magnetic interaction intensity between the cantilever magnet and the counter magnet in terms of geometrical parameters. A simple model provides a sound prediction of the behavior of the system. Finally, we measured the energy required to store a bit of information on the system that, for the considered protocols, is bounded by the energy barrier separating the two stable states.
Estimation of steady-state leakage current in polycrystalline PZT thin films
Authors: Podgorny Yury , Vorotilov Konstantin , Sigov Alexander
Published: September 2016

Estimation of the steady state (or “true”) leakage current Js in polycrystalline ferroelectric PZT films with the use of the voltage-step technique is discussed. Curie-von Schweidler (CvS) and sum of exponents (Σexp) models are studied for current-time J (t) data fitting. Σexp model (sum of three or two exponents) gives better fitting characteristics and provides good accuracy of Js estimation at reduced measurement time thus making possible to avoid film degradation, whereas CvS model is very sensitive to both start and finish time points and give in many cases incorrect results. The results give rise to suggest an existence of low-frequency relaxation processes in PZT films with characteristic duration of tens and hundreds of seconds.
Asparagopsis taxiformis decreases enteric methane production from sheep
Authors: Li Xixi , Norman Hayley C. , Kinley Robert D. , Laurence Michael , Wilmot Matt , Bender Hannah , de Nys Rocky , Tomkins Nigel
Published: September 2016

Asparagopsis taxiformis concentrates halogenated compounds that are known to inhibit cobamide-dependent methanogenesis in vitro and, therefore, has potential to mitigate enteric methane production. The present study investigated the effect of Asparagopsis on methane (CH4) production from sheep offered a high-fibre pelleted diet (offered at 1.2 × maintenance) at five inclusion levels of Asparagopsis for 72 days (0% (control), 0.5%, 1%, 2% and 3% organic matter basis as offered). Individual animal CH4 measurements were conducted at 21-day intervals using open-circuit respiration chambers. Asparagopsis inclusion resulted in a consistent and dose-dependent reduction in enteric CH4 production over time, with up to 80% CH4 mitigation at the 3% offered rate compared with the group fed no Asparagopsis (P < 0.05). Sheep fed Asparagopsis had a significantly lower concentration of total volatile fatty acids and acetate, but a higher propionate concentration. No changes in liveweight gain were identified. Supplementing Asparagopsis in a high-fibre diet (<2% organic matter) resulted in significant and persistent decreases in enteric methanogenesis over a 72-day period. Granulomatous and keratotic ruminal mucosa changes were identified in several sheep with Asparagopsis supplementation. While the outcomes of the present study may be extrapolated to feedlot to achieve the antimethanogenic effect associated with Asparagopsis, further work is required to define the long-term effects on productivity and animal health.
Macroinvertebrate community succession under variable flow regimes in subtropical Australia
Authors: Stitz Leigh , Fabbro Larelle , Kinnear Susan
Published: September 2016

Seasonal changes in hydrology are important factors influencing abiotic conditions and subsequently the biota. Although these effects have been studied in tropical catchments and in central arid Australia, subtropical ephemeral streams have largely been ignored. In the present study, three ephemeral streams in Central Queensland were monitored over 15 months. We hypothesised that macroinvertebrate abundance would increase gradually following the initial flow pulse and that abundance would increase until the pools began drying, with sensitive taxa only present during higher flow. In all, 69 families from 14 orders were collected in 128 samples. Significant relationships were not detected between low flow conditions and taxa richness (P>0.05). Principal component analysis showed that the macroinvertebrate communities did not change in response to the drying of pools. Significant differences were not observed between taxa richness, abundance nor tolerant taxa during varied periods of flow (P>0.05). Sensitive taxa were most abundant during high-flow periods with comparatively less abundance during no flow and drying periods. This study provides novel information on the flow-linked succession of macroinvertebrate communities in subtropical ephemeral streams and the results are important in informing the development of riverine indices and models used to manage subtropical environments.