bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of silylmethoxy groups as inducers of efficient room temperature phosphorescence from precious-metal-free organic luminophores
Authors: Shimizu Masaki , Kinoshita Takumi , Shigitani Ryosuke , Miyake Yusuke , Tajima Kunihiko
Published: December 2017

Crystals of and PMMA films doped with 2,5-bis(silylmethoxy)-1,4-diaroylbenzenes exhibit efficient green phosphorescence at room temperature.
A structurally-characterized peroxomanganese(iv) porphyrin from reversible O2 binding within a metal–organic framework
Authors: Gallagher Audrey T. , Lee Jung Yoon , Kathiresan Venkatesan , Anderson John S. , Hoffman Brian M. , Harris T. David
Published: December 2017

Within a MOF, a side-on peroxomanganese(iv) porphyrin has been isolated and comprehensively examined.
Controllable extension of hairpin-structured flaps to allow low-background cascade invasive reaction for a sensitive DNA logic sensor for mutation detection
Authors: Liu Yun-Long , Wu Hai-Ping , Zhou Qiang , Song Qin-Xin , Rui Jian-Zhong , Guan Xiao-Xiang , Zhou Guo-Hua , Zou Bing-Jie
Published: December 2017

A sensitive DNA logic sensor was constructed based on a controllable-extension bridged cascade invasive reaction.
A green and scalable route to yield porous carbon sheets from biomass for supercapacitors with high capacity
Authors: Wang Cunjing , Wu Dapeng , Wang Hongju , Gao Zhiyong , Xu Fang , Jiang Kai
Published: December 2017

A green route is developed to prepare hierarchical porous carbon sheets (HPCS) from biomass directly under air atmosphere without inert gas protection. The as-prepared HPCS with ultra-thin structure, rich O doping sites and large SSA demonstrate excellent specific capacitance and stability when used in supercapacitor.
Expanded biomass-derived hard carbon with ultra-stable performance in sodium-ion batteries
Authors: Zhu Ziyi , Liang Feng , Zhou Zhongren , Zeng Xiaoyuan , Wang Ding , Dong Peng , Zhao Jinbao , Sun Shigang , Zhang Yingjie , Li Xue
Published: December 2017

We prepared hard carbon in a sheet-like structure as a high-density anode for sodium-ion batteries.
Interface engineering of the Ni(OH)2–Ni3N nanoarray heterostructure for the alkaline hydrogen evolution reaction
Authors: Gao Min , Chen Lanlan , Zhang Zhenhua , Sun Xuping , Zhang Shusheng
Published: December 2017

It is highly attractive but challenging to design and develop noble-metal-free catalysts with outstanding electrocatalytic activity for the hydrogen evolution reaction (HER) in alkaline media.
Superelastic and ultralight polyimide aerogels as thermal insulators and particulate air filters
Authors: Qian Zhenchao , Wang Zhen , Chen Yi , Tong Shengrui , Ge Maofa , Zhao Ning , Xu Jian
Published: December 2017

Superelasticity, recoverable ultimate strain of 99%, has been obtained for fibrous polyimide aerogels.
A small amount of nanoparticulated plant biomass, lignin, enhances the heat tolerance of poly(ethylene carbonate)
Authors: Shikinaka K. , Sotome H. , Kubota Y. , Tominaga Y. , Nakamura M. , Navarro R. R. , Otsuka Y.
Published: December 2017

A small amount of non-deteriorated lignin dramatically enhances the heatproof properties of a synthetic polymer.
In situ encapsulation of core–shell-structured Co@Co3O4 into nitrogen-doped carbon polyhedra as a bifunctional catalyst for rechargeable Zn–air batteries
Authors: Guo Ziyang , Wang Fengmei , Xia Yuan , Li Jinli , Tamirat Andebet Gedamu , Liu Yanru , Wang Lei , Wang Yonggang , Xia Yongyao
Published: December 2017

Co@Co3O4@NC-900 is designed and used as a catalyst for bulk and flexible Zn–air batteries which display good electrochemical performance.
3D printing of pearl/CaSO4composite scaffolds for bone regeneration
Authors: Du Xiaoyu , Yu Bin , Pei Peng , Ding Huifeng , Yu Baoqing , Zhu Yufang
Published: December 2017

Pearl/calcium sulfate (pearl/CaSO4) composite scaffolds were successfully fabricated by 3D printing with a hydration process, and showed enhanced physicochemical and biological properties for bone regeneration.
Design of UV-crosslinked polymeric thin layers for encapsulation of piezoelectric ZnO nanowires for pressure-based fingerprint sensors
Authors: Bouvet-Marchand A. , Graillot A. , Volk J. , Dauksevicius R. , Sturm C. , Grundmann M. , Saoutieff E. , Viana A. , Christian B. , Lebedev V. , Radó J. , Lukács I. E. , N. Q. Khánh , Grosso D. , Loubat C.
Published: December 2017

Elaboration of UV-crosslinked polymeric thin layer for pressure-based fingerprint sensor.
The antiferromagnetic state in ultrathin LaNiO3 layer supported by long-range exchange bias in LaNiO3/SrTiO3/La0.7Sr0.3MnO3 superlattices
Authors: Zhou Guowei , Ji Huihui , Zhang Jun , Bai Yuhao , Quan Zhiyong , Xu Xiaohong
Published: December 2017

The long-range exchange bias in LNO/STO/LSMO superlattices is a useful way to support the antiferromagnetic state in the LNO layer.
Simple synthesis of uniformly small gold nanoparticles for sensitivity enhancement in colorimetric detection of Pb2+ by improving nanoparticle reactivity and stability
Authors: Xiahou Yujiao , Zhang Peina , Wang Jin , Huang Lihui , Xia Haibing
Published: December 2017

Sensitivity of lead detection (upto 0.1 nM) is greatly improved by enhancing the reactivity and stability of small gold nanoparticles.
Atomic-scale mechanisms of defect- and light-induced oxidation and degradation of InSe
Authors: Kistanov Andrey A. , Cai Yongqing , Zhou Kun , Dmitriev Sergey V. , Zhang Yong-Wei
Published: December 2017

Perfect InSe possesses high chemical stability against oxidation. However, the presence of intrinsic Se vacancy and light illumination can markedly accelerate its oxidation.
Confocal laser feedback microscopy for in‐depth imaging applications
Authors: Mowla A. , Taimre T. , Bertling K. , Wilson S. , Rakić A. D.
Published: December 2017

We propose confocal laser feedback microscopy for in‐depth imaging of highly scattering samples. This technique provides a compact configuration for microscopy in reflectance mode; it is based on laser feedback interferometry which is a sensing technique where the laser acts as both transmitter and receiver of the beam. Operating at 850 nm, it offers an ideal platform for non‐invasive and in vivo imaging of soft biological tissues. To explore the technique, the authors performed microscopic imaging of micro‐glass‐spheres (with diameter sizes of 10–20 µm) deep within an agar gel sample, at depth of 0.43 mm from the surface. Experimental results show the feasibility of a compact, low‐cost, and simple laser‐scanning microscope with possible biomedical imaging applications.
Based on STATCOM direct current full‐order terminal sliding mode control
Authors: Chen Ruo‐bo , Zheng Xue‐mei , Pang Song‐nan , Li Xin
Published: December 2017

This study proposes a static synchronous compensator (STATCOM), which cannot only detect and compensate for reactive current according to the real‐time change of grid reactive current, but also maintain the current phase and voltage phase of grid consistent. Aimed at the shortages existing in the control of STATCOM at present, such as the parameters are difficult to adjust and the calculation is very complex, a sliding mode controller for STATCOM reactive current inner‐loop control system is designed. Finally, the control logic is evaluated in Matlab/Simulink, and the simulation results are compared with the traditional proportional integral (PI) control design. It is shown that the proposed method is able to achieve the response performance of the conventional PI method, and has stronger robustness against external disturbance.
Practical Synthesis of a PCP-Type Pincer Ligand and Its Metal Complexes­
Authors: Matoba Kazutaka , Nishibayashi Yoshiaki , Eizawa Aya , Nishimura Shunsuke , Arashiba Kazuya , Nakajima Kazunari
Published: December 2017

A synthetic method for N-heterocyclic carbene- and phosphine-based PCP-type pincer ligand is described on a large scale. Some transition-metal complexes bearing the PCP-type pincer ligand are prepared and characterized by X-ray crystal structure analysis.
Synthesis of Tricyclic Marine Alkaloids, Cylindricines, Lepadiformines, Fasicularin, and Polycitorols: A Recent Update
Authors: Chiba Shunsuke , Kaga Atsushi
Published: December 2017

Cylindricines, lepadiformines, and fasicularin are tricyclic marine alkaloids bearing perhydropyrrolo- and pyrido[2,1-j] frameworks having divergent chemical functionalities. They have been isolated from marine tunicates over the last two decades and found to have a range of cytotoxicity such as DNA-alkylating ability. Recently, polycitorols have emerged as a new member of this alkaloid family. Their unique structural features and biological activities have intrigued many researchers and challenged them in their synthesis. This review describes recent syntheses of the tricyclic alkaloids based on key synthetic approaches.

1 Introduction

2 Total and Formal Syntheses

2.1 Overview of Synthetic Strategies

2.2 Azaspirocycle (BC Ring) Approaches

2.3 Indolizidine (AC Ring) Approaches

2.4 Azadecalin (AB Ring) Approaches

2.5 Tandem Cyclization Approaches

3 Summary and Future Perspective
Indium-Catalyzed Direct Conversion of Lactones into Thiolactones and Selenolactones in the Presence of Elemental Sulfur and Selenium
Authors: Sakai Norio , Horikawa Shuhei , Ogiwara Yohei
Published: December 2017

The direct conversion of lactones into thiolactones with elemental sulfur (S8) catalyzed by InCl3/PhSiH3 in a one-pot reaction is described. This catalytic system was successfully applied to the novel preparation of selenolactones from lactones and selenium.
Continuous Flow Conversion of Glycerol into Chemicals: An Overview
Authors: Len Christophe , Delbecq Frederic , Cara Corpas Cristobal , Ruiz Ramos Encarnacion
Published: December 2017

This report highlights the recent advances for glycerol valorization to valuable products in liquid phase continuous flow systems using different types of catalysts and processes. The main biobased chemicals obtained from glycerol, such as acrolein, lactic acid, dihydroxyacetone, propanediols, glycerol carbonate, solketal, acetin, alkyl ethers, and oligomers, will be presented.

1 Introduction

2 Continuous Dehydration

2.1 Without Added Catalyst

2.2 With Acid Catalyst

3 Continuous Oxidation

4 Continuous Hydrogenolysis

5 Continuous Carbonatation

6 Continuous Ketalization

7 Continuous Esterification

8 Continuous Etherification

9 Continuous Oligomerization

10 Outlook

11 Conclusion
Outcomes of the Ulnar Shortening Osteotomy Using a Dynamic Compression Plate on the Ulnar Surface of the Ulna
Authors: Rozée Bernhard , Elgammal Ahmed
Published: December 2017

Background The purpose of this study is to evaluate the results of patients with ulnar impaction syndrome treated with diaphyseal osteotomy using freehand technique and fixation with ulnar osteotomy compression plate placed on the ulnar surface of the ulna.

Materials and Methods A retrospective chart review of patients with ulnar impaction syndrome between 2010 and 2014 identified 38 patients. The following clinical data were observed: patient age, sex, range of motion, grip strength, visual analog scale (VAS), Disabilities of the Arm, Shoulder, and Hand (DASH) score, radiological assessment, and complications. The mean follow-up period is 30 months. Eleven patients were excluded from the study.

Results Compared with the contralateral side, the 27 patients included in this study attained 93 to 96% of wrist and forearm motion and 81% of the grip strength. The average DASH score was 18 in a mean follow-up period of 30 months. Three patients required plate removal and one case showed nonunion and a further operation was needed. Two patients reported persistent ulnar-sided wrist pain.

Conclusion We concluded that placing the ulnar osteotomy plate on the ulnar surface of the ulna is a quicker procedure, with less soft tissue dissection and irritation, and very high union rate.

Level of Evidence Level IV.
Tumor Vascularity Does Not Predict Response to Yttrium-90 Radioembolization for Hepatic Metastases from Colorectal Cancer
Authors: Naydenov Alipi , Harris William , Johnson Guy , Hippe Daniel , Padia Siddharth
Published: December 2017

The purpose of this study was to determine whether the degree of tumor vascularity based on imaging has an impact on tumor response and survival in patients with metastatic colorectal cancer (mCRC) to the liver undergoing yttrium-90 radioembolization. A retrospective study of 75 mCRC patients from a single-institution undergoing radioembolization was performed over a 7-year period. Tumors were categorized as hypo- or hypervascular based on digital subtraction angiography (DSA) and C-arm CT during mapping angiography. Tumor response and survival were compared between each group, after undergoing radioembolization. Hypervascular tumors were present in 37 of 75 (49%) patients according to DSA. Of 37 patients who underwent C-arm CT during the procedure, 22 (59%) had tumors classified as hypervascular. There were no significant differences in tumor response rates when vascularity was stratified by DSA or C-arm CT. Median progression-free survival (PFS) was 111 versus 128 days (p = 0.41) between DSA hypervascular and hypovascular cases, and median overall survival (OS) was 439 versus 342 days (p = 0.96). When stratified by C-arm CT, median PFS was 313 versus 244 days (p = 0.83) and median OS was 489 versus 342 days (p = 0.74) for hypervascular and hypovascular cases, respectively. Tumor vascularity based on DSA or C-arm CT does not predict imaging response or survival after radioembolization and should not be used as a criterion for selecting candidates for radioembolization for hepatic mCRC.
Dual Energy Computed Tomography in Musculoskeletal Imaging, with Focus on Fragility Fractures of the Pelvis
Authors: Hackenbroch Carsten , Riesner Hans-Joachim , Lang Patricia , Stuby Fabian , Beer Meinrad , Friemert Benedikt , Palm Hans-Georg ,   AG Becken III
Published: December 2017

Dual energy computed tomography (DECT) is a constantly evolving technology, which opens up new diagnostic possibilities. It is particularly valuable for musculoskeletal (MSK) imaging. Due to the lack of recognition and availability of dual energy scanners, routine use is only established in a few centres. The intention of this review is to show the possibilities and fields of applications of the DECT in MSK imaging, as well as to describe technical principles and typical indications. We mainly focus on the use of DECT in the context of fragility fractures of the pelvis. The use of the DECT in pelvic fractures of the elderly could combine the advantages of CT diagnostics – fast and continuous availability, lower costs by dispensing with a supplementary MRI examination – and the high sensitivity of MRI to oedema in fragility fractures. Furthermore, the latest DECT scanners are dose neutral, so that these examinations can also be carried out without increased radiation exposure.
Kompetenzbasierter Lernzielkatalog „Rehabilitation, Physikalische Medizin, Naturheilverfahren“ (RPMN) – revidierte Fassung
Authors: Mau Wilfried , Liebl Max , Deck Ruth , Lange Uwe , Smolenski Ulrich , Walter Susanne , Gutenbrunner Christoph ,   (für die Kommissionen Aus-, Fort- und Weiterbildung der DGRW# und DGPMR+)
Published: December 2017

Seit der ersten Publikation der Lernziele für den Querschnittsbereich „Rehabilitation, Physikalische Medizin, Naturheilverfahren (RPMN)“ im Medizinstudium im Jahr 2004 ist auf Grund heterogener Lehrangebote an den Fakultäten sowie neuer Impulse v. a. aus dem „Nationalen Kompetenzbasierten Lernzielkatalog Medizin (NKLM)“ und dem „Masterplan Medizinstudium 2020“ eine Revision sinnvoll. Deshalb haben die Deutsche Gesellschaft für Rehabilitationswissenschaften e. V. und die Deutsche Gesellschaft für Physikalische Medizin und Rehabilitation e. V. in einem strukturierten Konsensprozess nach der DELPHI-Methodik die Lernziele reduziert und übersichtlicher gegliedert. Besonders relevante Lernziele werden hervorgehoben. Alle Lernziele werden der kognitiven und Methodenkompetenz (Level 1 „Kennen und Können“) bzw. der Handlungskompetenz (Level 2 „Beherrschen“) zugeordnet. Auf die Lernziele im weniger detaillierten NKLM wird konkret verwiesen. Mit diesem revidierten Lernzielkatalog wird ein Beitrag zur Weiterentwicklung der kompetenzbasierten und in Kernbereichen homogeneren humanmedizinischen Lehre zu RPMN an den Fakultäten geleistet.
Liebe Leserinnen und Leser
Authors: Schliehe Ferdinand
Published: December 2017

Zunächst eine persönliche Mitteilung: Nach nunmehr 18 Jahren als Mitherausgeber der Zeitschrift „Die Rehabilitation“ möchte ich meine Mitwirkung zum Jahresende 2017 beenden. Die Zeitschrift hat in dieser Zeit eine erfreuliche Entwicklung genommen und hat sich als fachliches Forum für Wissenschaft und Praxis in der Rehabilitation fest etabliert. Besonders freue ich mich, dass mit dem Relaunch in diesem Jahr eine Aktualisierung und Modernisierung des Zeitschriftenkonzeptes gelungen ist und dabei auch Anregungen unserer Leserinnen und Leser aufgenommen werden konnten. Die Zeitschrift spiegelt die Komplexität und Vielfalt der rehabilitativen Versorgung ebenso wider wie die umfangreichen Forschungsaktivitäten auf diesem Gebiet. Mit dieser Vielseitigkeit kann die Zeitschrift auf sehr unterschiedliche Interessen und Bedürfnisse eingehen. Sie ergänzt dies durch regelmäßige Übersichtsarbeiten sowie auch Schwerpunkt- und Sonderhefte. Auch die CME-Beiträge bieten für alle einen konzentrierten und aktuellen Überblick zu speziellen Themen.
The culmination of an inverse cascade: Mean flow and fluctuations
Authors: Frishman Anna
Published: December 2017

Two dimensional turbulence has a remarkable tendency to self-organize into large, coherent structures, forming a mean flow. The purpose of this paper is to elucidate how these structures are sustained and what determines them and the fluctuations around them. A recent theory for the mean flow will be reviewed. The theory assumes that turbulence is excited by a forcing supported on small scales and uses a linear shear model to relate the turbulent momentum flux to the mean shear rate. Extending the theory, it will be shown here that the relation between the momentum flux and mean shear is valid, and the momentum flux is non-zero, for both an isotropic forcing and an anisotropic forcing, independent of the dissipation mechanism at small scales. This conclusion requires taking into account that the linear shear model is an approximation to the real system. The proportionality between the momentum flux and the inverse of the shear can then be inferred most simply on dimensional grounds. Moreover, for a homogeneous pumping, the proportionality constant can be determined by symmetry considerations, recovering the result of the original theory. The regime of applicability of the theory, its compatibility with observations from simulations, a formula for the momentum flux for an inhomogeneous pumping, and results for the statistics of fluctuations will also be discussed.
“FORCE” learning in recurrent neural networks as data assimilation
Authors: Duane Gregory S.
Published: December 2017

It is shown that the “FORCE” algorithm for learning in arbitrarily connected networks of simple neuronal units can be cast as a Kalman Filter, with a particular state-dependent form for the background error covariances. The resulting interpretation has implications for initialization of the learning algorithm, leads to an extension to include interactions between the weight updates for different neurons, and can represent relationships within groups of multiple target output signals.
Development of a low power miniature linear ion trap mass spectrometer with extended mass range
Authors: Li Gang , Li Detian , Cheng Yongjun , Pei Xiaoqiang , Zhang Huzhong , Wang Yongjun , Sun Jian , Dong Meng
Published: December 2017

A miniaturized ion trap mass spectrometer with continuous atmospheric pressure interface was built, which could be used in conjunction with internal ionization (in-vacuum plasma ionization) and external ionization (electrospray ionization). To improve its mass range, a supplemental AC signal frequency scan mode was performed for this miniature mass spectrometer, in which the fundamental RF signal was remained constant with an amplitude as low as several hundreds volts. Experiments showed that the upper limit of the mass range can be extended to 2500 Da for the miniature mass spectrometer developed in this work, and the power consumption can be reduced by 2/5, while maintaining good balance with performance parameters such as stability, sensitivity, and resolution. Due to the improvement in mass range and significant reduction in energy consumption compared with the instrument using the traditional resonant ejection mode, the scan method developed in this work is helpful to promote the miniature design of mass spectrometers for field analysis and space exploration.
Jet formation of SF6 bubble induced by incident and reflected shock waves
Authors: Zhu Yuejin , Yu Lei , Pan Jianfeng , Pan Zhenhua , Zhang Penggang
Published: December 2017

The computational results of two different cases on the evolution of the shock-SF6 heavy bubble interaction are presented. The shock focusing processes and jet formation mechanisms are analyzed by using the high resolution of computation schemes, and the influence of reflected shock waves is also investigated. It is concluded that there are two steps in the shock focusing process behind the incident shock wave, and the density and pressure values increase distinctly when the shock focusing process is completed. The local high pressure and vorticities in the vicinity of the downstream pole can propel the formation of the jet behind the incident shock wave. In addition, the gas is with the rightward velocity before the reflected shock wave impinges on the bubble; therefore, the evolutions of the waves and the bubble are more complicated when the reflected shock wave impinges on the SF6 bubble. Furthermore, the different end wall distances would affect the deformation degree of the bubble before the interaction of the reflected shock wave; therefore, the different left jet formation processes are found after the impingement of reflected shock waves when L = 27 mm. The local high pressure zones in the vicinity of the left bubble interface and the impingement of different shock waves can induce the local gas to shift the rightward velocity to the leftward velocity, which can further promote the formation of jets.
Modeling study of radiation characteristics with different impurity species seeding in EAST
Authors: Liu X. J. , Deng G. Z. , Wang L. , Liu S. C. , Zhang L. , Li G. Q. , Gao X.
Published: December 2017

A critical issue for EAST and future tokamak machines such as ITER and China Fusion Engineering Testing Reactor is the handling of excessive heat load on the divertor target plates. As an effective means of actively reducing and controlling the power fluxes to the target plates, localized impurity (N, Ne, and Ar) gas puffing from the lower dome is investigated by using SOLPS5.0 for an L-mode discharge on EAST with double null configuration. The radiative efficiency and distribution of different impurities are compared. The effect of N, Ne, and Ar seeding on target power load, the power entering into scrape-off layer (SOL), Psep, and their concentration in SOL along the poloidal length and edge effective ion charge number (Zeff) which are closely related to core plasma performance are presented. The simulation results indicate that N, Ne, and Ar seeding can effectively reduce the peak heat load and electron temperature at divertor targets similarly. N seeding can reach the highest radiative loss fraction and both N and Ar strongly radiate power in the divertor region, while the radiative power inside the separatrix for Ar seeding is also significant. Ne radiates power mainly around the separatrix and X-point. Ne and Ar impurities' puffing results in a faster decrease of Psep than N seeding case; the reduction of Psep can eventually degrade the core performance of fusion plasma. Additionally, seeding with Ne has a totally larger concentration at the outer midplane and edge Zeff than those in N and Ar seeding cases; it suggests that N and Ar impurities are more acceptable than Ne in terms of fuel dilution for this discharge.
Upgraded flowing liquid lithium limiter for improving Li coverage uniformity and erosion resistance in EAST device
Authors: Zuo G. Z. , Hu J. S. , Maingi R. , Yang Q. X. , Sun Z. , Huang M. , Chen Y. , Yuan X. L. , Meng X. C. , Xu W. , Gentile C. , Carpe A. , Diallo A. , Lunsford R. , Mansfield D. , Osborne T. , Tritz K. , Li J. G.
Published: December 2017

We report on design and technology improvements for a flowing liquid lithium (FLiLi) limiter inserted into auxiliary heated discharges in the experimental advanced superconducting tokamak device. In order to enhance Li coverage uniformity and erosion resistance, a new liquid Li distributor with homogenous channels was implemented. In addition, two independent electromagnetic pumps and a new horizontal capillary structure contributed to an improvement in the observed Li flow uniformity (from 30% in the previous FLiLi design to >80% in this FLiLi design). To improve limiter surface erosion resistance, hot isostatic press technology was applied, which improved the thermal contact between thin stainless steel protective layers covering the Cu heat sink. The thickness of the stainless steel layer was increased from 0.1 mm to 0.5 mm, which also helped macroscopic erosion resilience. Despite the high auxiliary heating power up to 4.5 MW, no Li bursts were recorded from FLiLi, underscoring the improved performance of this new design.
Unravelling the progressive role of rattlers in thermoelectric clathrate and strategies for performance improvement: Concurrently enhancing electronic transport and blocking phononic transport
Authors: Yang Jia-Yue , Cheng Long , Hu Ming
Published: December 2017

Intermetallic clathrates, one class of guest-host systems with perfectly crystalline structures, hold great potential to be the “phonon glass – electron crystal” thermoelectric materials. Previous studies focus on revealing the atomistic origins of blocked phononic transport, yet little attention is drawn to the enhanced electronic transport. In this work, we investigate the binary type-I M8Si46 (M = Sr, Ba, Tl, and Pb) clathrates and unravel how rattlers concurrently block phononic transport and enhance electronic transport from first-principles. By comparing the empty and filled clathrates, the lattice thermal conductivity is greatly reduced by a factor of 21 due to the decrease in phonon relaxation time for propagative phonons over 0–6 THz by 1.5 orders of magnitude. On the other hand, rattlers bridge charge gaps among cages by donating electrons and thus drastically increase electrical conductivity. The concurrent realization of blocked phononic transport and enhanced electronic transport boosts the figure-of-merit (ZT) of empty clathrate by 4 orders of magnitude. Furthermore, by manipulating metallic rattlers and n-type doping, the power factor is markedly improved and ZT can reach 0.55 at 800 K. These results provide a quantitative description of the guest-host interaction and coupling dynamics from first-principles. The proposed strategy of manipulating ratting atoms and in-situ doping offers important guidance to engineer clathrates with high thermoelectric performance.
Multiple electrical phase transitions in Al substituted barium hexaferrite
Authors: Kumar Sunil , Supriya Sweety , Kar Manoranjan
Published: December 2017

Barium hexaferrite is known to be a very good ferromagnetic material. However, it shows very good dielectric properties, i.e., the dielectric constant is comparable to that of the ferroelectric material. However, its crystal symmetry does not allow it to be a ferroelectric material. Hence, the electrical properties have revived the considerable research interest on these materials, not only for academic interest, but also for technological applications. There are a few reports on temperature dependent dielectric behavior of these materials. However, the exact cause of dielectric as well as electrical conductivity is yet to be established. Hence, Al (very good conducting material) substituted barium hexaferrite (BaFe12−xAlxO19, x = 0.0–4.0) has been prepared by following the modified sol-gel method to understand the ac and DC electrical properties of these materials. The crystal structure and parameters have been studied by employing the XRD and FTIR techniques. There are two transition temperatures, which have been observed in the temperature dependent ac dielectric and DC resistivity measurement. The response of dielectric behaviors to temperature is similar to that of the ferroelectric material; however, the dielectric polarization is due to the polaron hopping, which is evident from the DC resistivity analysis. Hence, the present observations lead to understand the electrical properties of barium hexaferrite. The frequency dependent dielectric dispersion can be understood by the modified Debye model. More interestingly, the dielectric constant decreases and DC resistivity increases with the increase in the Al concentration, which has the correlation between bond length modifications in the crystal due to substitution.
A nonlinear approach to transition in subcritical plasmas with sheared flow
Authors: Pringle Chris C. T. , McMillan Ben F. , Teaca Bogdan
Published: December 2017

In many plasma systems, introducing a small background shear flow is enough to stabilize the system linearly. The nonlinear dynamics are much less sensitive to sheared flows than the average linear growth rates, and very small amplitude perturbations can lead to sustained turbulence. We explore the general problem of characterizing how and when the transition from near-laminar states to sustained turbulence occurs, with a model of the interchange instability being used as a concrete example. These questions are fundamentally nonlinear, and the answers must go beyond the linear transient amplification of small perturbations. Two methods that account for nonlinear interactions are therefore explored here. The first method explored is edge tracking, which identifies the boundary between the basins of attraction of the laminar and turbulent states. Here, the edge is found to be structured around an exact, localized, traveling wave solution that is qualitatively similar to avalanche-like bursts seen in the turbulent regime. The second method is an application of nonlinear, non-modal stability theory which allows us to identify the smallest disturbances which can trigger turbulence (the minimal seed for the problem) and hence to quantify how stable the laminar regime is. The results obtained from these fully nonlinear methods provide confidence in the derivation of a semi-analytic approximation for the minimal seed.
Note: An avalanche transistor-based nanosecond pulse generator with 25 MHz repetition rate
Authors: Beev Nikolai , Keller Jonas , Mehlstäubler Tanja E.
Published: December 2017

We have developed an avalanche transistor-based pulse generator for driving the photocathode of an image intensifier, which comprises a mainly capacitive load on the order of 100 pF. The circuit produces flat-top pulses with a rise time of 2 ns, a FWHM of 10 ns, and an amplitude of tens of V at a high repetition rate in the range of tens of MHz. The generator is built of identical avalanche transistor sections connected in parallel and triggered in a sequence, synchronized to a reference rf signal. The described circuit and mode of operation overcome the power dissipation limit of avalanche transistor generators and enable a significant increase of pulse repetition rates. Our approach is naturally suited for synchronized imaging applications at low light levels.
Resonances of Newtonian fluids in elastomeric microtubes
Authors: Torres Rojas Aimee M. , Pagonabarraga I. , Corvera Poiré E.
Published: December 2017

We analyze the dynamic behavior of Newtonian fluids in elastic tubes subject to pulsatile pressure gradients and show that the interplay between the viscosity of the fluid, the elasticity of the wall, and the characteristic size of the confining media gives rise to a rich phenomenology that includes resonances. We find that these resonances are relevant for small confining geometries with low Young’s moduli, typical of elastomeric materials in microfluidics. These resonances disappear beyond a certain tube radius, a certain Young’s modulus, and below a certain fluid viscosity. In order to guide potential experiments, we present results for mineral oil flowing through polydimethylsiloxane microtubes and find resonances of the order of few tens of kHz.
Luminescence of Eu3+ in GaN(Mg, Eu): Transitions from the 5D1 level
Authors: Singh A. K. , O'Donnell K. P. , Edwards P. R. , Cameron D. , Lorenz K. , Kappers M. J. , Boćkowski M. , Yamaga M. , Prakash R.
Published: December 2017

Eu-doped GaN(Mg) exemplifies hysteretic photochromic switching between two configurations, Eu0 and Eu1(Mg), of the same photoluminescent defect. Using the above-bandgap excitation, we studied the temperature dependence of photoluminescence (TDPL) of transitions from the excited 5D1 level of Eu3+ for both configurations of this defect. During sample cooling, 5D1→7F0,1,2 transitions of Eu0 manifest themselves at temperatures below ∼200 K, while those of Eu1(Mg) appear only during switching. The observed line positions verify crystal field energies of the 7F0,1,2 levels. TDPL profiles of 5D1→7F1 and 5D0→7FJ transitions of Eu0 show an onset of observable emission from the 5D1 level coincident with the previously observed, but hitherto unexplained, decrease in the intensity of its 5D0→7FJ emission on cooling below 200 K. Hence, the 5D0→7FJ TDPL anomaly signals a back-up of 5D1 population due to a reduction in phonon-assisted relaxation between 5D1 and 5D0 levels at lower temperatures. We discuss this surprising result in the light of temperature-dependent transient luminescence measurements of Eu0.
Development of vortex structures in the wake of a sharp-edged bluff body
Authors: Fukuda K. , Balachandar R. , Barron R. M.
Published: December 2017

The development of streamwise vortical structures in the wake of an infinitely long inclined flat plate is investigated using detached eddy simulation. The numerical model is validated by comparing with available experimental results. The spanwise vortices shed from the leading and trailing edges are captured near the body in the midspan plane and are shown to quickly dissipate in the downstream wake. The generation of streamwise vortical structures and their interaction with the large-scale spanwise vortices are elucidated using the λ2-criterion to identify the vortices. The spanwise wavelength of the streamwise vortical structures is found to lie in the range corresponding to the mode B instability reported in the previous studies of wake transition. The temporal evolution of the streamwise vortices is studied in the near-wake region. The spanwise evolution of the flow clearly indicates the role of the streamwise vortices in dissipating the spanwise structures. The streamwise vortical structures also exert an influence on the shear layer at the trailing edge resulting in a corrugated pattern during their development. Cross-sectional planes normal to the plate are also used to examine the interaction between the streamwise and spanwise vortices. This combination of two-dimensional velocity fields and contours (in planes normal and parallel to the freestream and to the plate) and three-dimensional iso-surfaces provides a more complete picture of the formation of the complex fluid structures in the flow around a bluff body.
Thermal analysis of high-bandwidth and energy-efficient 980 nm VCSELs with optimized quantum well gain peak-to-cavity resonance wavelength offset
Authors: Li Hui , Wolf Philip , Jia Xiaowei , Lott James A. , Bimberg Dieter
Published: December 2017

The static and dynamic performance of vertical-cavity surface-emitting lasers (VCSELs) used as light-sources for optical interconnects is highly influenced by temperature. We study the effect of temperature on the performance of high-speed energy-efficient 980 nm VCSELs with a peak wavelength of the quantum well offset to the wavelength of the fundamental longitudinal device cavity mode so that they are aligned at around 60 °C. A simple method to obtain the thermal resistance of the VCSELs as a function of ambient temperature is described, allowing us to extract the active region temperature and the temperature dependence of the dynamic and static parameters. At low bias currents, we can see an increase of the −3 dB modulation bandwidth f−3dB with increasing active region temperature, which is different from the classically known situation. From the detailed analysis of f−3dB versus the active region temperature, we obtain a better understanding of the thermal limitations of VCSELs, giving a basis for next generation device designs with improved temperature stability.
Wave-induced collisions of thin floating disks
Authors: Yiew L. J. , Bennetts L. G. , Meylan M. H. , Thomas G. A. , French B. J.
Published: December 2017

Collisions between two thin floating disks forced by regular water waves are studied for a range of wave amplitudes and lengths, using laboratory wave basin experiments and a mathematical model. Three collision regimes are identified from the experiments in terms of collision frequency and strength, and the collisions are shown to be caused by drift for short incident wavelengths and relative surge motion between the disks for longer incident waves. The model is based on slope-sliding theory for the wave-induced disk motions and rigid-body collisions. It is shown to predict collision frequencies and velocities accurately for intermediate–long incident wavelengths. Incorporating drift and wave scattering forces into the model is shown to capture the collision behaviours for short incident wavelengths.
Density functional theory based analysis of the origin of traps at the InAs/Si hetero-interface
Authors: Sant S. , Luisier M. , Schenk A.
Published: December 2017

The growth of III-V semiconductors on Si generates defects at the III-V/Si interface which are known to degrade the performance of electronic devices where this interface is an active region. This paper presents a density functional theory based analysis of the InAs/Si interface with the aim to find the origin of traps at this interface. The optimized structure is obtained by structural minimization and is compared with a filtered Transmission Electron Microscopy image from the literature. The good qualitative agreement between the two results validates the atomic model of the InAs/Si interface. Electronic structural calculations are performed on the geometrically optimized InAs/Si slab to identify the interface trap levels. The study reveals that the InAs/Si interface traps originate from unsaturated orbitals present on Arsenic interface atoms. The saturation of the unsaturated As atoms by H or S is able to passivate the interface and to reduce the Dit.
Mixed quantum/semiclassical wave-packet dynamical method for condensed-phase molecular spectroscopy signals
Authors: Kovac Philip A. , Cina Jeffrey A.
Published: December 2017

We report the successful application of a recently developed mixed quantum/semiclassical wave-packet dynamical theory to the calculation of a spectroscopic signal, the linear absorption spectrum of a realistic small-molecule chromophore in a cryogenic environment. This variational fixed vibrational basis/Gaussian bath (FVB/GB) theory avails itself of an assumed time scale separation between a few, mostly intramolecular, high-frequency nuclear motions and a larger number of slower degrees of freedom primarily associated with an extended host medium. The more rapid, large-amplitude system dynamics is treated with conventional basis-set methods, while the slower time-evolution of the weakly coupled bath is subject to a semiclassical, thawed Gaussian trial form that honors the overall vibrational ground state, and hence the initial state prepared by its Franck-Condon transfer to an excited electronic state. We test this general approach by applying it to a small, symmetric iodine-krypton cluster suggestive of molecular iodine embedded in a low-temperature matrix. Because of the relative simplicity of this model complex, we are able to compare the absorption spectrum calculated via FVB/GB dynamics using Heller’s time-dependent formula with one obtained from rigorously calculated eigenenergies and Franck-Condon factors. The FVB/GB treatment proves to be accurate at approximately 15-cm−1 resolution, despite the presence of several thousand spectral lines and a sequence of various-order system-bath resonances culminating at the highest absorption frequencies in an inversion of the relative system and bath time scales.
Enhanced performance of ferroelectric materials under hydrostatic pressure
Authors: Chauhan Aditya , Patel Satyanarayan , Wang Shuai , Novak Nikola , Xu Bai-Xiang , Lv Peng , Vaish Rahul , Lynch Christopher S.
Published: December 2017

Mechanical confinement or restricted degrees of freedom have been explored for its potential to enhance the performance of ferroelectric devices. It presents an easy and reversible method to tune the response for specific applications. However, such studies have been mainly limited to uni- or bi-axial stress. This study investigates the effect of hydrostatic pressure on the ferroelectric behavior of bulk polycrystalline Pb0.99Nb0.02(Zr0.95Ti0.05)0.98O3. Polarization versus electric field hysteresis plots were generated as a function of hydrostatic pressure for a range of operating temperatures (298–398 K). The application of hydrostatic pressure was observed to induce anti-ferroelectric like double hysteresis loops. This in turn enhances the piezoelectric, energy storage, energy harvesting, and electrocaloric effects. The hydrostatic piezoelectric coefficient (dh) was increased from 50 pCN−1 (0 MPa) to ∼900 pC N−1 (265 MPa) and ∼3200 pCN−1 (330 MPa) at 298 K. Energy storage density was observed to improve by more than 4 times under pressure, in the whole temperature range. The relative change in entropy was also observed to shift from ∼0 to 4.8 J kg−1 K−1 under an applied pressure of 325 MPa. This behavior can be attributed to the evolution of pinched hysteresis loops that have been explained using a phenomenological model. All values represent an improvement of several hundred percent compared to unbiased performance, indicating the potential benefits of the proposed methodology.
The output voltage model and experiment of magnetostrictive displacement sensor based on Weidemann effect
Authors: Wang Bowen , Li Yuanyuan , Xie Xinliang , Huang Wenmei , Weng Ling , Zhang Changgeng
Published: December 2017

Based on the Wiedemann effect and inverse magnetostritive effect, the output voltage model of a magnetostrictive displacement sensor has been established. The output voltage of the magnetostrictive displacement sensor is calculated in different magnetic fields. It is found that the calculating result is in an agreement with the experimental one. The theoretical and experimental results show that the output voltage of the displacement sensor is linearly related to the magnetostrictive differences, (λl-λt), of waveguide wires. The measured output voltages for Fe-Ga and Fe-Ni wire sensors are 51.5mV and 36.5mV, respectively, and the output voltage of Fe-Ga wire sensor is obviously higher than that of Fe-Ni wire sensor under the same magnetic field. The model can be used to predict the output voltage of the sensor and to provide guidance for the optimization design of the sensor.
Magnetic and structural characterization of ultra-thin Fe (222) films
Authors: Loving Melissa G. , Brown Emily E. , Rizzo Nicholas D. , Ambrose Thomas F.
Published: December 2017

Varied thickness body centered cubic (BCC) ultrathin Fe films (10-50Å) have been sputter deposited onto Si (111) substrates. BCC Fe with the novel (222) texture was obtained by H- terminating the Si (111) starting substrate then immediately depositing the magnetic films. Structural results derived from grazing incidence x-ray diffraction and x-ray reflectivity confirm the crystallographic texture, film thickness, and interface roughness. Magnetic results indicate that Fe (222) exhibits soft magnetic switching (easy axis), high anisotropy (hard axis), which is maintained across the thickness range, and a positive magnetostriction (for the thicker film layers). The observed soft magnetic switching in this system makes it an ideal candidate for future magnetic memory development as well as other microelectronics applications that utilize magnetic materials.
Shapes and paths of an air bubble rising in quiescent liquids
Authors: Sharaf D. M. , Premlata A. R. , Tripathi Manoj Kumar , Karri Badarinath , Sahu Kirti Chandra
Published: December 2017

Shapes and paths of an air bubble rising inside a liquid are investigated experimentally. About three hundred experiments are conducted in order to generate a phase plot in the Galilei and Eötvös numbers plane, which separates distinct regimes in terms of bubble behaviour. A wide range of the Galilei and Eötvös numbers are obtained by using aqueous glycerol solutions of different concentrations as the surrounding fluid and by varying the bubble size. The dynamics are investigated in terms of shapes, topological changes, and trajectories of the bubbles. Direct numerical simulations are conducted to study the bubble dynamics, which show excellent agreement with the experiments. To the best of our knowledge, this is the first time an experimentally obtained phase plot showing the distinct behaviour of an air bubble rising in a quiescent medium is reported for such a large range of Galilei and Eötvös numbers.
A complete equation of state for non-ideal condensed phase explosives
Authors: Wilkinson S. D. , Braithwaite M. , Nikiforakis N. , Michael L.
Published: December 2017

The objective of this work is to improve the robustness and accuracy of numerical simulations of both ideal and non-ideal explosives by introducing temperature dependence in mechanical equations of state for reactants and products. To this end, we modify existing mechanical equations of state to appropriately approximate the temperature in the reaction zone. Mechanical equations of state of the Mie-Grüneisen form are developed with extensions, which allow the temperature to be evaluated appropriately and the temperature equilibrium condition to be applied robustly. Furthermore, the snow plow model is used to capture the effect of porosity on the reactant equation of state. We apply the methodology to predict the velocity of compliantly confined detonation waves. Once reaction rates are calibrated for unconfined detonation velocities, simulations of confined rate sticks and slabs are performed, and the experimental detonation velocities are matched without further parameter alteration, demonstrating the predictive capability of our simulations. We apply the same methodology to both ideal (PBX9502, a high explosive with principal ingredient TATB) and non-ideal (EM120D, an ANE or ammonium nitrate based emulsion) explosives.
Ab initio calculation of electronic structure and magnetic properties of R2Fe14BNx (R = Pr,Nd)
Authors: Tian Guang , Zha Liang , Yang Wenyun , Qiao Guanyi , Wang Changsheng , Yang Yingchang , Yang Jinbo
Published: December 2017

The site preference of N atom for R2Fe14BNx (R= Pr, Nd) and the interstitial nitrogen effect on the magnetic properties have been studied by the first-principles method. It was found that the nitrogen is more likely to occupy the 4e site for Pr2Fe14BNx compound, while 4f site for Nd2Fe14BNx. When N atoms entering some specific crystal sites (such as 2a and 4f), the total magnetic moments of these compounds are not reduced, but slightly increased. Although the doping of N may reduce the total magnetic moments of some R2Fe14B compounds in the cases of optimal occupancy, the volumetric effect caused by N doping can still change the electron density distributions of Fe near the Fermi level, improving the magnetic ordering temperature of such compounds.