bluuebunny/crossref_metadata_2025 huggingface dataset:
Der gynäkologische Notfall – Teil 1: Präsentationssymptom unklares Abdomen
Authors: Weißleder Anne , Egbe Anne , Beinkofer Daniela , Kulla Martin , Treffer Dominik
Published: August 2019

Der Artikel stellt das typische Präsentationssymptom des gynäkologischen Notfalls – das unklare Abdomen der Frau – anhand von Szenarien aus dem prä- und innerklinischen Bereich vor. Die genaue Notfallanamnese und -untersuchung werden für die gynäkologische Patientin modifiziert. Wichtige Differenzialdiagnosen des unklaren Abdomens sowie weitere gynäkologische Notfallszenarien, wie z.B. genitales Trauma, werden in den kommenden Ausgaben erläutert.
Systematic Review and Meta-Analysis of Randomized Controlled Trials on the Effect of SGLT2 Inhibitor on Blood Leptin and Adiponectin Level in Patients with Type 2 Diabetes
Authors: Wu Peili , Wen Weiheng , Li Jitong , Xu Jie , Zhao Min , Chen Hong , Sun Jia
Published: August 2019

Sodium glucose cotransporter 2 (SGLT2) inhibitors are a new kind of hypoglycemic drugs that improve glucose homeostasis by inhibiting renal glucose reabsorption. Recent studies have shown that SGLT2 inhibitors can also mediate body metabolism through regulation of adipokines level, but the effects of SGLT2 inhibitors on the concentration of adipokines (leptin and adiponectin) remains controversial. This meta-analysis was set out to evaluate the changes in circulating leptin and adiponectin levels in patients with type 2 diabetes mellitus (T2DM) receiving SGLT2 inhibitors therapy. Ten randomized controlled trials (RCTs), that evaluated the effects of SGLT2 inhibitors on blood leptin and adiponectin levels in patients with type 2 diabetes, were identified by performing a systematic search of Pubmed, Embase, Cochrane, and Web of science databases through July 2018. Data were calculated using a random-effects model and presented as standardized mean difference (SMD) and 95% conﬁdence interval (CI). Compared with placebo, treatment with SGLT2 inhibitors contributed to a decreased circulating leptin levels (SMD −0.29, 95% CI −0.56, −0.03) and an increased circulating adiponectin levels (SMD 0.30, 95% CI 0.22, 0.38). SGLT2 inhibitor treatment was associated with decreased circulating leptin levels and increased circulating adiponectin levels, which might contribute to the beneficial effects of SGLT2 inhibitors on metabolic homeostasis.
Medizinische Rehabilitation bei MS: Barrieren und Facilitatoren der
Inanspruchnahme aus Patientensicht
Authors: Giesler Jürgen M. , Klindtworth Katharina , Nebe Angelika , Glattacker Manuela
Published: August 2019

Ziel der Studie Leistungen der stationären medizinischen
Rehabilitation werden von MS-Erkrankten vergleichsweise selten genutzt,
obwohl Belege für deren Wirksamkeit vorliegen. Ziel der vorliegenden
Studie war es deshalb, von den Betroffenen wahrgenommene Barrieren und
Facilitatoren der Inanspruchnahme stationärer Rehabilitationen zu
ermitteln.

Methodik Auf der Basis umfangreicher Vorarbeiten wurde ein Fragebogen
mit 45 Items entwickelt, der bundesweit von 590 MS-Erkrankten mehrheitlich
online beantwortet wurde. Die Auswertung erfolgte mittels deskriptiver
statistischer Verfahren.

Ergebnisse Mehrheitlich hohe Erwartungen der Befragten an die
MS-Rehabilitation betreffen v.a. Aspekte der Strukturqualität der
Einrichtungen und die Mitwirkung an Behandlungsentscheidungen. Als Barrieren
einer Inanspruchnahme werden zu geringe Kenntnisse der Inhalte und
Abläufe der medizinischen Rehabilitation genannt und eine z.T. als
zu gering erlebte Unterstützung durch Ärzte in Bezug auf das
Stellen eines Antrags auf Rehabilitation. Als weitere Barrieren werden eine
als gering erlebte Transparenz der Bewilligungsprozesse und – von
einem kleineren Anteil der Befragten – auch berufs- oder
familienbezogene Aspekte gesehen.

Schlussfolgerungen Auf Basis der Befunde lassen sich verschiedene
Empfehlungen formulieren, die zu einem Abbau von Barrieren der
Inanspruchnahme einer medizinischen Rehabilitation von MS-Erkrankten
beitragen können. Diese beinhalten Hinweise auf bzw. die
Bereitstellung von im Einzelfall abzustimmender Information über die
medizinische Rehabilitation bei MS (Ziele, Nutzen und Inhalte), die
Erhöhung der Transparenz des Antrags- und Genehmigungsprozesses
sowie die Stärkung der Rolle ambulanter Fachärzte.
Profiles of Phenolic Acids and Triterpene Glycosides in Commercial and Cultivated Black Cohosh
Authors: Bittner Marian , Schenk Regina , Springer Andreas , Melzig Matthias F.
Published: August 2019

The medicinal plant Actaea racemosa is a perennial, whose rhizome (black cohosh rhizome) is usually wild harvested on a multiton scale to meet market requirements. Since this North American species is increasingly endangered, cultivation is needed. Even though studies prove that cultivation is possible, it has not been widely established. This may be due to a different quality of cultivated material, which does not comply with current pharmacopoeial requirements. This study compares contents and chromatographic fingerprints of phenolic acids and triterpene glycosides in different types of black cohosh rhizomes. Commercial batches from wild harvests were compared to individual plants from the wild and from cultivation. Phenolic acidsʼ contents and profiles were generally comparable between wild harvesting and cultivation. On the contrary, the total triterpene glycoside content was significantly lower in cultivation (p ≤ 0.001). In individual plants, different profiles of triterpene glycosides occurred. Possibly, specimen or chemotype selection for cultivation would cause a shift of the triterpene glycoside profile of cultivation batches away from the common pattern found in batches from wild harvesting. Potentially, such differences have an impact on the efficacy of black cohosh herbal products, if cultivated plant material is used for manufacturing.
Nitric Oxide and Opioids Involvement in Isobolographic Nsaids Antinociception
Authors: Miranda Hugo F. , Noriega Viviana , Sierralta Fernando , Poblete Paula , Aranda Nicolás , Prieto Juan Carlos
Published: August 2019

Different NSAIDs are used as antinociceptive in various analgesic assays, among which should be mentioned: ibuprofen, ketorolac , ketoprofen, meloxicam , paracetamol and others. It has been shown that NSAIDs possess antinociceptive activity by blocking cyclooxygenase enzymes (COXs). The present study was designed to evaluate the possible involvement of the nitridergic pathway due to L-NAME and the opioidergic route by NTX in the antinoception induced by NSAIDs using a murine pain model the tail flick test in an automatic tail flick algesiometer. The antinociception was evaluated by means of isobolographic analysis. The interaction between the combination of NSAIDs, via i.p., on basis of their ED25, demonstrated that the coadministration of the drugs were synergistic with the exception of the lack of effect in combination of meloxicam with ibuprofen and with ketorolac, since the result was additive. These data validate that the NSAIDs administered alone or in combinations produce antinociception in which other mechanisms of action must be added to the simple inhibition of COXs. In addition, the pretreatment of the mice with L-NAME and NTX does not change previous isobolographic parameters of the mixture of NSAIDs.
A New Surgical Technique for Internal Shoulder Contractures Secondary to Obstetric Brachial Plexus Injury: An Anterior Coracohumeral Ligament Release
Authors: Sarac C. , Hogendoorn S. , Nelissen R.G.H.H.
Published: August 2019

Background Obstetric brachial plexus injuries result from traction injury during delivery; 30% of these children sustain persisting functional limitations related to an external rotation deficit of the shoulder. The aim of this study was to compare the intraoperative gain in external rotation after a posterior subscapular release and an anterior coracohumeral ligament release.

Methods This is a prospective study on 102 children with an internal rotation contracture of the shoulder who received either a posterior subscapular release (posterior skin incision along the medial border of the scapula of 3–5 cm) or an anterior (5-mm skin incision) coracohumeral ligament release between 1996 and 2010. After general anesthesia, internal and external rotations in both adduction and abduction were measured before and after the surgical release.

Results After a posterior subscapular release, the intraoperative external rotation improved with a mean of 64 degrees (95% confidence interval [CI]: 54–74; p < 0.001) in adduction and with a mean of 41 degrees (95% CI: 32–49; p < 0.001) in abduction. After an anterior coracohumeral ligament release, external rotation increased with a mean of 61 degrees (95% CI: 56–66; p < 0.001) in adduction and a mean of 42 degrees in abduction (95%CI: 39–45, p < 0.001). Differences between these two groups were not statistically different.

Conclusion The anterior release technique shows comparable results with the posterior subscapular release. And since it is performed through a smaller incision of 5 mm, this is our preferred method to increase passive external rotation.

Level of evidence II.
Comparison of cross-flow turbine performance under torque-regulated and speed-regulated control
Authors: Polagye Brian , Strom Ben , Ross Hannah , Forbush Dominic , Cavagnaro Robert J.
Published: August 2019

When experimentally evaluating the performance of a wind or water current turbine, one must impose a regulating torque on the turbine rotor by electrical or mechanical means. Some options limit this controlling torque to a purely resistive quantity, while servomotors and stepper motors allow torque to be applied in the direction of turbine rotation. Any control mode that results in net positive power for a turbine may be of interest for energy harvesting, and all of these are net “fluid-driven.” Here, we present experiments that characterize the power, torque, and force coefficients of a cross-flow turbine operated at a constant rotational speed or under a constant imposed control torque. Time- and phase-average performance coefficients are largely equivalent for the two strategies although torque-regulated control is restricted to a narrower range of rotational speeds and the two strategies result in slightly different blade kinematics.
No replica symmetry breaking phase in the random field Ginzburg-Landau model
Authors: Itoi C. , Utsunomiya Y.
Published: August 2019

It is proved that the variance of a spin overlap vanishes in the infinite volume limit of the random field Ginzburg-Landau model whose truncated two point correlation functions satisfy the Fortuin-Kasteleyn-Ginibre inequality.
Enhanced magnetoresistance in NiFe/GaAs/Fe hybrid magnon valve
Authors: Yang Long , Shipp Nicholas , Pu Yong , Chen Yequan , Chen Yiyi , He Liang , Ruan Xuezhong , Liu Wenqing , Xu Yongbing
Published: August 2019

The magnon valve (MV), which consists of a one spacer layer sandwiched between two ferromagnetic layers, is a potential spintronic device. The operation principle of the magnon valve depends on magnon current propagating between the two magnetic layers. More specifically, the magnon current is induced in one ferromagnetic layer and then injects magnons into the other ferromagnetic layer through the spacer layer. During this process, the magnetization of the injected ferromagnetic layer is changed, leading to the different relative magnetic orientations of the two magnetic layers. Here, we investigated the electromagnetic property of the NiFe/GaAs/Fe magnon valve assisted by microwaves with various frequencies. We find that the magnetoresistance (MR) of the magnon valve increases up to 40% when applying an external 3.4GHz microwave. The increase in the magnetoresistance results from the magnon current propagating between the two ferromagnetic layers. The magnons induced by the external microwave share the same phase, and thus the magnon current can penetrate into a 70 μm thick GaAs by coherent propagation.
Growth of graphitic carbon layers around silicon carbide nanowires
Authors: Mishra Neeraj , Bosi Matteo , Rossi Francesca , Salviati Giancarlo , Boeckl John , Iacopi Francesca
Published: August 2019

We demonstrate the ability to synthesize graphitic carbon sheets around cubic silicon carbide nanowires via an alloy-mediated catalytic process. The transmission electron microscopy analysis shows multilayer graphitic carbon sheets with a large interatomic layer distance of ∼0.45 nm, suggesting the presence of oxygen in the graphitic system. Oxygen-related peaks observed by energy-dispersive X-ray spectroscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy further confirm the oxidation of the graphitic carbon layers. A detailed investigation of the Raman spectra reveals a turbostratic stacking of the graphitic carbon layers. The turbostratic nature and the presence of oxidation in the graphitic carbon surrounding the silicon carbide nanowires make them a suitable platform for further functionalization, of particular interest for biosensing, as both graphitic carbon and silicon carbide are biocompatible.
Gradient magnet design for simultaneous detection of electrons and positrons in the intermediate MeV range
Authors: Tiwari G. , Kupfer R. , Jiao X. , Gaul E. , Hegelich B. M.
Published: August 2019

We report the design and development of a compact electron and positron spectrometer based on tapered neodymium iron boron magnets to characterize the pairs generated in laser-matter experiments. The tapered design forms a gradient magnetic field component allowing energy dependent focusing of the dispersed charged particles along a chosen detector plane. The mirror symmetric design allows for simultaneous detection of pairs with energies from 2 MeV to 500 MeV with an accuracy of ≤10% in the wide energy range from 5 to 110 MeV for a parallel beam incident on a circular aperture of 20 mm. The energy resolution drops to ≤20% for 4–90 MeV range for a divergent beam originating from a point source at 20 cm away (i.e., a solid angle of ∼8 milli steradians), with ≤10% accuracy still maintained in the narrower energy range from 10 to 55 MeV. It offers higher solid angle acceptance, even for the divergent beam, compared to the conventional pinhole aperture-based spectrometers. The proposed gradient magnet is suitable for the detection of low flux and/or monoenergetic type electron/positron beams with finite transverse sizes and offers unparalleled advantages for gamma-ray spectroscopy in the intermediate MeV range.
Theoretical prediction and experimental demonstration of inter-valley scattering induced Inverse Spin Hall effect for hot electrons in GaAs
Authors: Mudi Priyabrata , Khamari Shailesh K. , Sharma T. K.
Published: August 2019

Realization of the Inverse Spin Hall Effect (ISHE) with hot electrons in direct bandgap semiconductors is an intriguing puzzle. Here, we report the influence of steady state carrier accumulation in the satellite L valley on the establishment of ISHE in the GaAs epilayer. Steady state carrier accumulation is calculated by analytically solving the rate equations where the whole conduction band is divided into four distinct regions based on the energy and momentum. Electron-hole generation, energy and spin relaxation, and various recombination mechanisms are considered in the theoretical framework where carrier accumulation in the L valley of GaAs is driven by intervalley scattering. This is then followed by a set of experiments to measure the photoinduced ISHE at excitation energy (Eex) of 1.65, 1.94, and 2.33 eV, where significant differences are theoretically predicted. The measured values of ISHE signal are thereafter compared with the numerically calculated ones, which establish the validity of the proposed formalism. Further, the physical origin of ISHE signal is investigated for different regimes that lead to the observation of intervalley scattering induced ISHE at Eex = 2.33 eV.
Competitive conductive mechanism of interstitial Ag and oxygen vacancies in Ag/Ta2O5/Pt stack
Authors: Hu Qi , Fan Zhiqiang , Huang Anping , Zhang Xinjiang , Zhao Rumeng , Gao Qin , Ji Yuhang , Dou Wenzhen , Wang Mei , Shi Hongliang , Xiao Zhisong , Jiang Xiangwei , Chu Paul K.
Published: August 2019

The transport properties of Ag/Ta2O5/Pt with coexisting interstitial Ag and oxygen vacancies are examined by density-functional theory and nonequilibrium Green's function calculation. The results show that the coexistence of interstitial Ag and oxygen vacancies results in a reduced transmission coefficient, implying an antagonistic interaction between Ag and oxygen vacancies. Interstitial Ag atoms may take the position of oxygen vacancies and block the oxygen vacancy channel. Alternatively, oxygen vacancies attract electrons from nearby Ag channels thereby reducing the conductance. By comparing the different dual-component channels, it is found that Ag and oxygen vacancies tend to form a complete oxygen vacancy channel with a few Ag atoms giving rise to higher conductance. Our calculation reveals a competitive conductive mechanism of interstitial Ag and oxygen vacancies and a promising strategy to investigate multicomponent channels and improve the design of future synaptic devices.
Low lattice thermal conductivity by alloying SnTe with AgSbTe2 and CaTe/MnTe
Authors: Chen Zhiyu , Gao Bo , Tang Jing , Guo Xuming , Li Wen , Ang Ran
Published: August 2019

SnTe-AgSbTe2 alloys have shown promising thermoelectric performance due to phonon-vacancy scattering, while SnTe alloyed with high-solubility monotellurides such as CaTe/MnTe has also shown enhanced thermoelectric performance owing to band convergence. However, to what level the combined effect on thermoelectrics by alloying SnTe with AgSbTe2 and CaTe/MnTe exists, especially for the quantitative relationship between the vacancy concentration and lattice thermal conductivity, still remains a mystery. Here, a spontaneous strategy has shown that combining AgSbTe2 with CaTe/MnTe in SnTe alloys can lead to an inherent valence band convergence and improved electronic performance. In particular, a low lattice thermal conductivity (∼0.4 W/m K), which approaches the amorphous limit of SnTe, is achieved in (Sn0.95Ca0.05Te)0.75(AgSbTe2)0.125 with 3% excess of Sn. The Debye-Callaway model provides a good clarification of underlying physics for the reduced lattice thermal conductivity as well as quantifies the contribution of vacancy scattering. The present finding demonstrates the excellent potential for advancing the thermoelectric performance by SnTe-based alloys.
Designs and experiments of a novel compact E-shaped wideband planar antenna array for high-power microwave application
Authors: Xu Liang , Yuan Cheng-Wei , Zhang Qiang , Sun Yun-Fei
Published: August 2019

A novel compact E-shaped wideband planar antenna array (CEWPA) is designed and fabricated for high-power microwave (HPM) application. The CEWPA is a kind of planar antenna and it has a lot of advantages such as low profile, wideband, high efficiency, easy to manufacture, and light weight. Compared with traditional planar antenna arrays, it overcomes the disadvantage of low power capacity through special metal structure designs. The CEWPA consists of 60 antenna elements and achieved miniaturization by an innovative array layout. In addition, it has reached a relative bandwidth of 33% (VSWR < 2) at a center frequency of 2.1 GHz in simulation and over 20% in experiment. On the other hand, the measured gain at the cold test is greater than 20 dB in the whole bandwidth while the radiation patterns are in agreement with the simulation. In addition, excited by nanosecond level pulses, the power capacity of the whole system is more than 140 MW in a high-power test.
Vertical dynamics in community functioning of biofilm-dwelling ciliates during the colonisation process in coastal waters of the Yellow Sea
Authors: Bai Xiaoyun , Guo Congcong , Abdullah Al Mamun , Warren Alan , Xu Henglong
Published: August 2019

Multifunctional trait analysis is increasingly recognised as an effective tool for assessing ecosystem function and environmental quality. Here, a baseline study was performed at four depths (i.e. 1, 2, 3.5 and 5m) in Yellow Sea coastal waters of northern China in order to determine the optimal depth for bioassessment using biological traits of biofilm-dwelling ciliates. Community-weighted means (CWM) from functional traits system were used to summarise the trait distribution and functional diversity of ciliates among the four depths during a 1-month colonisation period. Functional trait distribution revealed a clear temporal variation among the four depths. In total, 3 of 17 functional traits (i.e. feeding type, body size and flexibility) showed significant temporal patterns. Bootstrapped averaging and permutational multivariate analysis of variance (PERMANOVA) tests demonstrated that the colonisation pattern of biofilm-dwelling ciliates as expressed by CWM at 1 and 2m differed significantly from those at 3.5 and 5m. Functional diversity indices showed lower variability at 1 and 2m than at 3.5 and 5m. These results suggest that 1 and 2m are the preferred sampling depths for bioassessment of marine water quality using biological traits of biofilm-dwelling ciliates.
Autophosphorylation is sufficient to release Mps1 kinase from native kinetochores
Authors: Koch Lori B. , Opoku Kwaku N. , Deng Yi , Barber Adrienne , Littleton Aimee J. , London Nitobe , Biggins Sue , Asbury Charles L.
Published: August 2019

Significance

Chromosomes carry our genetic material and must be precisely copied and partitioned into daughter cells during cell division. To ensure correct partitioning, a signaling cascade called the spindle assembly checkpoint delays cell division until all chromosomes are correctly attached to microtubules, the dynamic filaments that drive chromosome movements. If even a single chromosome is unattached or incorrectly attached, an enzyme, Mps1, initiates checkpoint signaling by binding to and modifying kinetochores, the large protein complexes that connect chromosomes to microtubules. Here we identify conditions that promote Mps1 release from native kinetochore particles isolated from yeast. Our findings suggest how the checkpoint “wait” signals might be turned off when kinetochores bind microtubules.
Rainfall variations in central Indo-Pacific over the past 2,700 y
Authors: Tan Liangcheng , Shen Chuan-Chou , Löwemark Ludvig , Chawchai Sakonvan , Edwards R. Lawrence , Cai Yanjun , Breitenbach Sebastian F. M. , Cheng Hai , Chou Yu-Chen , Duerrast Helmut , Partin Judson W. , Cai Wenju , Chabangborn Akkaneewut , Gao Yongli , Kwiecien Ola , Wu Chung-Che , Shi Zhengguo , Hsu Huang-Hsiung , Wohlfarth Barbara
Published: August 2019

Significance

We present a high-resolution, replicated speleothem δ
18
O record from Klang Cave in southern Thailand that characterizes rainfall variation in NCIP over the past 2,700 y. This record reveals notable dry climate conditions during the current and past warm periods, similar to the observations in SCIP, which resemble enhanced El Niño-like conditions. Using a newly developed ITCZ shift index, we find a southward shifted ITCZ during the early MWP and the CWP. Our results suggest that detecting changes in rainfall due to anthropogenic forcing still remains indistinguishable from natural variability in the northern tropics.
IL-17 constrains natural killer cell activity by restraining IL-15–driven cell maturation via SOCS3
Authors: Wang Xuefu , Sun Rui , Hao Xiaolei , Lian Zhe-Xiong , Wei Haiming , Tian Zhigang
Published: August 2019

Significance

IL-17A promotes tumorigenesis, metastasis, and viral infection. However, the underlying mechanisms remain elusive. By using diverse gene-deficient mice, antibody depletion, and animal models, we show that IL-17A promotes tumorigenesis, metastasis, and viral infection by constraining NK cell antitumor and antiviral activity via inhibition of NK cell maturation. The ablation of IL-17A signaling increases terminally mature CD27
−
CD11b
+
NK cells, whereas constitutive IL-17A signaling reduces terminally mature NK cells. IL-17A suppresses IL-15–induced phosphorylation of STAT5 via up-regulation of SOCS3 in NK cells, leading to inhibition of NK cell terminal maturation. Therefore, IL-17A acts as the checkpoint during NK cell terminal maturation, which suggests potential interventions to defend against tumors and infections.
Phosphorylation-guarded light-harvesting complex II contributes to broad-spectrum blast resistance in rice
Authors: Liu Muxing , Zhang Suobing , Hu Jiexiong , Sun Wenxian , Padilla Jonas , He Yanglan , Li Ying , Yin Ziyi , Liu Xinyu , Wang Wenhao , Shen Danyu , Li Dayong , Zhang Haifeng , Zheng Xiaobo , Cui Zhongli , Wang Guo-Liang , Wang Ping , Zhou Bo , Zhang Zhengguang
Published: August 2019

Significance

Environmental conditions strongly influence pathogen–host plant interactions. Rice blast erupts in overcast and rainy conditions, due not only to favorable environmental conditions but also to insufficient light, which reduces host resistance. Due to the importance of breeding of blast-resistant rice varieties, elucidation of light-regulated rice immunity is an important research goal. We revealed that light induces protein phosphorylation of a harvesting complex II protein, LHCB5, upon infection by the rice blast fungus
Magnaporthe oryzae
. Resistance governed by LHCB5 phosphorylation cosegregates with the progenies harboring the desirable haplotype promoter. This establishes the genetic basis of LHCB5-regulated resistance mediated by phosphorylation. Our study highlights a mechanism for light-dependent rice blast resistance that promises future breeding of blast-resistant rice varieties.
Graphene-like monolayer monoxides and monochlorides
Authors: Luo Bingcheng , Yao Yuan , Tian Enke , Song Hongzhou , Wang Xiaohui , Li Guowu , Xi Kai , Li Baiwen , Song Haifeng , Li Longtu
Published: August 2019

Significance

Since the discovery of graphene in 2004, 2D materials have sparked tremendous interest due to their fascinating optical, mechanical, and electronic properties, and their potential in catalysis, optoelectronic devices, energy storage, and conversion. After experimental and theoretical studies mainly focused on atomically thin nanomaterials with layered structures, the whole family of 2D materials is almost complete, and recently few new graphene-like materials were reported. Here, we report the discovery of graphene-like mononitrides, monoxides, monochlorides, and monoselenide monolayers, which have shown high dynamic, thermal, kinetic, and mechanic stabilities.
Effects of Y and Zn/Y on hot tearing susceptibility of Mg–Zn–Y–Zr alloys
Authors: Wei Ziqi , Liu Zheng , Sheng Xiaofang , Wang Yue , Zhang Zhenglai , Ju Yingdong
Published: August 2019

The effects of Y and Zn/Y on hot tearing susceptibility (HTS) of Mg–6.5Zn– xY–0.5Zr ( x = 4, 9, 12 and 18) and Mg–5Zn–13.5Y–0.5Zr alloys were investigated herein. The results illustrated that HTS of the investigated alloys decreased in the following order: Mg–6.5Zn–4Y–0.5Zr > Mg–6.5Zn–18Y–0.5Zr > Mg–6.5Zn–9Y–0.5Zr > Mg–6.5Zn–12Y–0.5Zr > Mg–5Zn–13.5Y–0.5Zr. The results also showed that HTS of the α-Mg-based alloy containing only LPSO phase was lower than that of the alloy containing only W-phase and (I+W) or (W+LPSO) mixed secondary phases. This was attributed to the coherence relationship between LPSO phase and α-Mg, and the bridging effect of LPSO phase.
The upper bound function of nonadiabatic dynamics in parametric driving quantum systems*
Authors: Zhang Lin , Liu Junpeng
Published: August 2019

The adiabatic control is a powerful technique for many practical applications in quantum state engineering, light-driven chemical reactions and geometrical quantum computations. This paper reveals a speed limit of nonadiabatic transition in a general time-dependent parametric quantum system that leads to an upper bound function which lays down an optimal criteria for the adiabatic controls. The upper bound function of transition rate between instantaneous eigenstates of a time-dependent system is determined by the power fluctuations of the system relative to the minimum gap between the instantaneous levels. In a parametric Hilbert space, the driving power corresponds to the quantum work done by the parametric force multiplying the parametric velocity along the parametric driving path. The general two-state time-dependent models are investigated as examples to calculate the bound functions in some general driving schemes with one and two driving parameters. The calculations show that the upper bound function provides a tighter real-time estimation of nonadiabatic transition and is closely dependent on the driving frequencies and the energy gap of the system. The deviations of the real phase from Berry phase on different closed paths are induced by the nonadiabatic transitions and can be efficiently controlled by the upper bound functions. When the upper bound is adiabatically controlled, the Berry phases of the electronic spin exhibit nonlinear step-like behaviors and it is closely related to topological structures of the complicated parametric paths on Bloch sphere.
Energetics and diffusion of point defects in Au/Ag metals: A molecular dynamics study*
Authors: Liu Zhi-Yong , He Bin , Qu Xin , Niu Li-Bo , Li Ru-Song , Wang Fei
Published: August 2019

To reveal the potential aging mechanism for self-irradiation in Pu–Ga alloy, we choose Au–Ag alloy as its substitutional material in terms of its mass density and lattice structure. As a first step for understanding the microscopic behavior of point defects in Au–Ag alloy, we perform a molecular dynamics (MD) simulation on energetics and diffusion of point defects in Au and Ag metal. Our results indicate that the octahedral self-interstitial atom (SIA) is more stable than the tetrahedral SIA. The stability sequence of point defects for He atom in Au/Ag is: substitutional site

>

octahedral interstitial site

>

tetrahedral interstitial site. The He–V cluster (

He

n

V

m

, V denotes vacancy) is the most stable at n = m. For the mono-vacancy diffusion, the MD calculation shows that the first nearest neighbour (1NN) site is the most favorable site on the basis of the nudged elastic band (NEB) calculation, which is in agreement with previous experimental data. There are two peaks for the second nearest neighbour (2NN) and the third nearest neighbour (3NN) diffusion curve in octahedral interstitial site for He atom, indicating that the 2NN and 3NN diffusion for octahedral SIA would undergo an intermediate defect structure similar to the 1NN site. The 3NN diffusion for the tetrahedral SIA and He atom would undergo an intermediate site in analogy to its initial structure. For diffusion of point defects, the vacancy, SIA, He atom and He–V cluster may have an analogous effect on the diffusion velocity in Ag.
Single-shot phase-shifting digital holography with a photon-sieve-filtering telescope*
Authors: Li You , Li Yao-Cun , Zhang Jun-Yong , Zhang Yan-Li , Li Xue-Mei
Published: August 2019

A method of single-shot phase-shifting digital holography with a photon-sieve-filtering telescope is proposed. Three copy images with different phases are first generated by use of a monofocal photon-sieve filter in Kepler telescope, and then interfere with the reference plane wave by a beam combiner. The hologram is captured by a charge-coupled device (CCD) in one single exposure. The complex-valued amplitude of the test object can be reconstructed by three-step phase-shifting interferometry through three frames of extracted sub-interferograms from the single-exposure hologram. The principle and simulation experiments are carried out and verified the validity of our proposed method. This method can be applied for snapshot imaging and three-dimensional object construction.
Vertical profile of aerosol extinction based on the measurement of O4of multi-elevation angles with MAX-DOAS*
Authors: Mou Fusheng , Luo Jing , Li Suwen , Shan Wei , Hu Lisha
Published: August 2019

A method for aerosol extinction profile retrieval using ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) is studied, which is based on a look-up table algorithm. The algorithm uses parametric method to represent aerosol extinction profiles and simulate different atmospheric aerosol states through atmospheric radiation transfer model. Based on the method, aerosol extinction profile was obtained during six cloud-free days. The O4differential air mass factor (dAMF) measured by MAX-DOAS is compared with the corresponding model results under different atmospheric conditions (R2=0.78). The aerosol optical thickness, aerosol weight factor in boundary layer, and the height of the boundary layer are obtained after the process of minimization and look-up table method. The retrieved aerosol extinction in boundary layer is compared with PM2.5 data measured by ground point instrument. The diurnal variation trends of the two methods are in good agreement. The correlation coefficients of the two methods are 0.71 when the aerosol optical thickness is smaller than 0.5. The results show that the look-up table method can obtain the aerosol state of the troposphere and provide validation for other instrument data.
Electronic structure of single-crystalline graphene grown on Cu/Ni (111) alloy film*
Authors: Zhang Xue-Fu , Liu Zhong-Hao , Liu Wan-Ling , Lu Xiang-Le , Li Zhuo-Jun , Yu Qing-Kai , Shen Da-Wei , Xie Xiao-Ming
Published: August 2019

Graphene with a Dirac cone-like electronic structure has been extensively studied because of its novel transport properties and potential application for future electronic devices. For epitaxially grown graphene, the process conditions and the microstructures are strongly dependent on various substrate materials with different lattice constants and interface energies. Utilizing angle-resolved photoemission spectroscopy, here we report an investigation of the electronic structure of single-crystalline graphene grown on Cu/Ni (111) alloy film by chemical vapor deposition. With a relatively low growth temperature, graphene on Cu/Ni (111) exhibits a Dirac cone-like dispersion comparable to that of graphene grown on Cu (111). The linear dispersions forming Dirac cone are as wide as 2 eV, with the Fermi velocity of approximately 1.1×106 m/s. Dirac cone opens a gap of approximately 152 meV at the binding energy of approximately 304 meV. Our findings would promote the study of engineering of graphene on different substrate materials.
First-principles study of the band gap tuning and doping control in CdSexTe1−x alloy for high efficiency solar cell*
Authors: Yang Jingxiu , Wei Su-Huai
Published: August 2019

CdTe is one of the leading materials for low cost, high efficiency thin-film solar cells with a nearly ideal band gap of 1.48 eV. However, its solar to electricity power conversion efficiency (PCE) is hindered by the relatively low open circuit voltage (V
OC) due to intrinsic defect related issues. Here, we propose that alloying CdTe with CdSe could possibly improve the solar cell performance by reducing the “ideal” band gap of CdTe to gain more short-circuit current from long-wavelength absorption without sacrificing much V
OC. Using the hybrid functional calculation, we find that the minimum band gap of the CdTe1−x
Se
x
alloy can be reduced from 1.48 eV at x = 0 to 1.39 eV at

x
=
0.32

, and most of the change come from the lowering of the conduction band minimum. We also show that the formation of the alloy can improve the p-type doping of CuCd impurity based on the reduced effective formation energy and nearly constant effective transition energy level, thus possibly enhance V
OC, thus PCE.
SymTopo: An automatic tool for calculating topological properties of nonmagnetic crystalline materials*
Authors: He Yuqing , Jiang Yi , Zhang Tiantian , Huang He , Fang Chen , Jin Zhong
Published: August 2019

Topological materials have novel properties both in their bulk and boundaries, thereby attracting a wide interest in the theoretical and experimental communities. The recent development of the topological quantum chemistry and symmetry-based indicator theory in this field has significantly simplified the procedure for determining the topological properties of nonmagnetic crystalline materials. Accordingly, a large number of new topological materials have been found by scanning large crystal databases. This study provides details on the algorithm used in the Catalogue of Topological Electronic Materials. Moreover, based on the algorithm, we develop an automatic package named SymTopo, which calculates the symmetry representations of any given nonmagnetic crystalline material and predicts its topological properties. This package may facilitate the discovery of more topological materials in the future.
Effect of strain on exciton dynamics in monolayer WS2*
Authors: Zhang Lu , He Da-Wei , He Jia-Qi , Fu Yang , Wang Yong-Sheng
Published: August 2019

The exciton dynamics in a WS2 monolayer with strain are studied by transient absorption measurements. We measure the differential transmission signal from monolayer WS2 as a function of the probe wavelength at different levels of strain applied to the sample. The differential transmission spectrum has a positive maximum value at about 614 nm and shows no significant strain dependence. By time-resolving the differential transmission signal, we find that the strain has a minimal effect on the exciton formation process. However, the exciton lifetime is significantly reduced by strain. These results provide useful information for applications of WS2 in flexible electronic and optoelectronic devices where strain is inevitable.
Quaternary antiferromagnetic Ba2BiFeS5 with isolated FeS4 tetrahedra*
Authors: Wang Shaohua , Zhang Xiao , Lei Hechang
Published: August 2019

We report the detailed physical properties of quaternary compound Ba2BiFeS5 with the key structural ingredient of isolated FeS4 tetrahedra. Magnetization and heat capacity measurements clearly indicate that Ba2BiFeS5 has a paramagnetic to antiferromagnetic transition at about 30 K. The calculated magnetic entropy above ordering temperature is much smaller than theoretical value for high-spin Fe3+ ion with S = 5/2, implying the possible short-range antiferromagnetic fluctuation in Ba2BiFeS5.
Non-perturbative multiphoton excitation studies in an excitonic coupled quantum well system using high-intensity THz laser fields
Authors: Gambhir Monica , Prasad Vinod
Published: August 2019

Multiphoton excitations and nonlinear optical properties of exciton states in GaAs/Al
x
Ga1−x
As coupled quantum well structure have been theoretically investigated under the influence of a time-varying high-intensity terahertz (THz) laser field. Non-perturbative Floquet theory is employed to solve the time-dependent equation of motion for the laser-driven excitonic quantum well system. The response to the field parameters, such as intensity and frequency of the laser electric field on the state populations, can be used in various optical semiconductor device applications, such as photodetectors, sensors, all-optical switches, and terahertz emitters.
Study on the nitridation of β-Ga2O3 films*
Authors: Cheng Fei , Li Yue-Wen , Zhao Hong , Xiu Xiang-Qian , Jia Zhi-Tai , Liu Duo , Hua Xue-Mei , Xie Zi-Li , Tao Tao , Chen Peng , Liu Bin , Zhang Rong , Zheng You-Dou
Published: August 2019

Single-crystal GaN layers have been obtained by nitriding β-Ga2O3 films in NH3 atmosphere. The effect of the temperature and time on the nitridation and conversion of Ga2O3 films have been investigated. The nitridation process results in lots of holes in the surface of films. The higher nitridation temperature and longer time can promote the nitridation and improve the crystal quality of GaN films. The converted GaN porous films show the single-crystal structures and low-stress, which can be used as templates for the epitaxial growth of high-quality GaN.
Effects of bismuth on structural and dielectric properties of cobalt-cadmium spinel ferrites fabricated via micro-emulsion route
Authors: Ahmed Sheikh Furhaj , Khalid Muhammad , Shahzad Shifa Muhammad , Noor ul Huda Khan Asghar H M , Aslam Sameen , Perveen Ayesha , ur Rehman Jalil , Azhar Khan Muhammad , Abbas Gilani Zaheer
Published: August 2019

Spinel ferrites have a significant role in high-tech applications. In the present work nano-crystalline ferrites having general formula Co0.5Cd0.5BixFe2−xO4with (x= 0.0, 0.05, 0.1, 0.15, 0.2, and 0.25) are synthesized via micro-emulsion route. Powder x-ray diffraction (XRD) studies discover the FCC spinel structure. Crystalline size is calculated in a range of 11 nm–15 nm. Lattice parameter calculations are reduced due to its substitution which leads to the exchange of large ionic radius of Fe3+for small ionic radius of Bi3+. The x-ray density is analyzed to increase with doping. Fourier transform infrared spectroscopy (FTIR) is performed to analyze absorption band spectra. The two absorption bands are observed in a range of 400 cm−1–600 cm−1, and they are the characteristic feature of spinel structure. Thermo-gravimetric analysis (TGA) reveals the total weight loss of nearly 1.98%. Dielectric analysis is carried out by impedance analyzer in a frequency span from 1 MHz to 3 GHz by using the Maxwell Wagner model. Dielectric studies reveal the decrease of dielectric parameters. The alternating current (AC) conductivity exhibits a plane behavior in a low frequency range and it increases with the applied frequency increasing. This is attributed to the grain effects in a high frequency range or may be due to the reduction of porosity. Real and imaginary part of impedance show the decreasing trend which corresponds to the grain boundary action. The imaginary modulus shows the occurrence of peak that helps to understand the interfacial polarization. Cole-Cole graph shows a single semicircle which confirms that the conduction mechanism is due to the grain boundaries at low frequency. Dielectric studies reveal the applicability of these ferrites in high frequency equipment, microwave applications, high storage media, and semiconductor devices.
Magnetoresistance hysteresis in topological Kondo insulator SmB6 nanowire*
Authors: Kong Ling-Jian , Zhou Yong , Song Hua-Ding , Yu Da-Peng , Liao Zhi-Min
Published: August 2019

SmB6, a topological Kondo insulator, with a gapped bulk state and metallic surface state has aroused great research interest. Here, we report an exotic hysteresis behavior of magnetoresistance in individual SmB6 nanowire in a temperature range in which both surface and bulk states contribute to the total conductance. Under a magnetic field parallel to the SmB6 nanowire, the resistance suddenly increases at the turning point from up-sweep to down-sweep of the magnetic field. The magnetoresistance hysteresis loops are well consistent with the magnetocaloric effect. Our results suggest that the SmB6 nanowires possess potential applications in the magnetic cooling technology.
Photoactivation experiment of 197Au(γ, n) performed with 9.17-MeV γ-ray from 13C(p, γ)14N*
Authors: Dang Yong-Le , Liu Fu-Long , Fu Guang-Yong , Wu Di , Wang Nai-Yan
Published: August 2019

High energy γ-ray can be used for nuclear waste transmutation by using the giant dipole resonance (GDR). The photonuclear reaction 197Au(γ, n) is known as a standard for studies on photoactivation experiments. The previous experiments on 197Au(γ, n) have been performed with bremsstrahlung, positron annihilation in flight or laser Compton scattering γ-ray. In this work, a new mono-energetic γ-ray source based on 13C(p, γ)14N reaction is used to measure the cross section of 197Au(

γ

, n) and the measured value is compared with the results obtained with other ways.
First principles study of interactions of oxygen–carbon–vacancy in bcc Fe*
Authors: You Yuan , Yan Mu-Fu , Yan Ji-Hong , Sun Gang , Wang Chao
Published: August 2019

Behaviors of C or O in bcc Fe and interactions of C–O and oxygen–carbon–vacancy (O–C–

□

) are investigated by first principles calculations. Octahedral interstitial site is the most stable position for an O atom in bcc Fe. The migration energy of an O atom in bcc Fe is 0.46 eV. The strength of O–Fe (1nn) bond (0.32) is slightly greater than that of Fe–Fe metallic bond (0.26). Repulsive interactions of C–C, O–O, and C–O exist in bcc Fe. When the concentration of FIA (FIA refers to C or O) is relatively high, a vacancy can attract four FIAs and form stable FIAs–

□

complex.
Distribution of metastable states of spin glasses
Authors: Schnabel Stefan , Janke Wolfhard
Published: August 2019

The complex behavior of systems like spin glasses, proteins or neural networks is typically explained in terms of a rugged energy or fitness landscape. Within the high-dimensional conformation space of these systems one finds features like barriers, saddle points, and metastable states whose number – at least in the case of spin glasses – grows exponentially with the size of the system. We propose a novel Monte Carlo sampling algorithm that employs an ensemble of short Markovian chains in order to visit all metastable states with equal probability. We apply this algorithm in order to measure the number of metastable states for the two-dimensional and the three-dimensional Edwards-Anderson model and compare with theoretical predictions.
Cluster expansion of the many-body Feynman path-integral for hard spheres
Authors: Bhardwaj Anish , Manousakis Efstratios
Published: August 2019

We apply a recently developed technique, which is based on a cluster expansion of the many-body Feynman path-integral, to the case of a dense system of distinguishable particles interacting with a hard-sphere potential. We find that our quantum hypernetted-chain approximation yields accurate results for the pair distribution function as compared to path-integral Monte Carlo results even in the high density regime.
Effect of low-temperature annealing on void-related microstructure in amorphous silicon: A computational study
Authors: Paudel Durga , Atta-Fynn Raymond , Drabold D. A. , Biswas Parthapratim
Published: August 2019

We present a computational study of void-induced microstructure in amorphous silicon (a-Si) by generating ultra-large models of a-Si with a void-volume fraction of 0.3%, as observed in small-angle X-ray scattering (SAXS) experiments. The relationship between the morphology of voids and the intensity of scattering in SAXS has been studied by computing the latter from the Fourier transform of the reduced pair-correlation function and the atomic-form factor of amorphous silicon. The effect of low-temperature annealing on scattering intensities and the microstructure of voids has been addressed, with particular emphasis on the shape and size of voids, by studying atomic rearrangements on void surfaces and computing the average radius of gyration of the voids from the spatial distribution of surface atoms and the intensity plots in the Guinier approximation. The study suggests that low-temperature annealing can lead to considerable restructuring of void surfaces, which is clearly visible from the three-dimensional shape of the voids but it may not necessarily reflect in one-dimensional scattering-intensity plots.
Devitrification of the Kob-Andersen glass former: Competition with the locally favored structure
Authors: Turci Francesco , Patrick Royall C. , Speck Thomas
Published: August 2019

Supercooled liquids are kinetically trapped materials in which the transition to a thermodynamically more stable state with long-range order is strongly suppressed. To assess the glass-forming abilities of a liquid empirical rules exist, but a comprehensive microscopic picture of devitrification is still missing. Here we study the crystallization of a popular model glass former, the binary Kob-Andersen mixture, in small systems. We perform trajectory sampling employing the population of the locally favored structure as order parameter. While for large population a dynamical phase transition has been reported, here we show that biasing towards a small population of locally favored structures induces crystallization, and we estimate the free energy difference. This result sheds new light on the competition between local and global structure in glass-forming liquids and its implications for crystallization.