Vanadium oxide nanotubes were synthesized by hydrothermal treatment from V2O5·nH2O sols as precursor and dodecylamine as structure-directing template. The morphology and structure of the nanotubes were characteri...Vanadium oxide nanotubes were synthesized by hydrothermal treatment from V2O5·nH2O sols as precursor and dodecylamine as structure-directing template. The morphology and structure of the nanotubes were characterized by SEM, TEM, XRD, TG-DTA and FTIR. The experimental results reveal that the duration of the hydrothermal treatment is of importance for obtaining VOx-NTs which have a layered structure. TG-DTA study indicates that V5+ cations in nanotubes are partially reduced to V4+ cations. The results from FTIR spectra indicate the difference in V-O vibrations between before and after hydrothermal treatment. From the results, it suggests that during hydrothermal treatment, the rearrangement of the vanadium oxide structure leads to the formation of VOx nanotubes from lamellar structure because of the presence of V4+ species.展开更多
Background:Smokeless tobacco is widely used by athletes to enhance performance.Nicotine is a central nervous system stimulant and acts on cardiocirculatory and metabolic systems,involving tissue blood flow and circula...Background:Smokeless tobacco is widely used by athletes to enhance performance.Nicotine is a central nervous system stimulant and acts on cardiocirculatory and metabolic systems,involving tissue blood flow and circulatory vasoreactivity.The aim of this study was to investigate the effects of the oral smokeless tobacco(Swedish snus(SS))on the perception of fatigue and time to exhaustion(TTE)during moderate-intensity aerobic exercise.Methods:Fourteen healthy non-tobacco male users were recruited for a double-blind,controlled crossover design(SS vs.snus placebo(SP)).Subjects were tested for 3 sessions:experimental session 1(Exp 1)consisted of an incremental test to determine the maximal aerobic power out-put(Wmax),whereas Exp2 and Exp3 consisted of exercising at 65%Wmax until exhaustion in SS or SP conditions.During Exp2 and Exp3,muscle and cerebral oxygenation was assessed by means of near-infrared spectroscopy,and the rating of perceived exertion(RPE)was recorded.Results:Comparing SS with SP tests,significant differences(p〈0.05)were found in the values of cerebral(-3%)and muscular tissues oxygenation(-4%)in the first 30 min of exercise.The RPE values were not significantly different between the 2 conditions(SS vs.SP).No significant difference was found in TTE(SS:54.25±21.84 min;SP:50.01±17.03 min).Conclusion:This study showed that muscular and cerebral oxygenation increased significantly with snus administration during an endurance exercise until exhaustion,but this did not affect fatigue perception and TTE.The results showed that snus could not be considered an ergogenic substance in non-tobacco users.2018 Published by Elsevier B.V.on behalf of Shanghai University of Sport.This is an open access article under the CC BY-NC-ND license.(http://creativecommons.org/licenses/by-nc-nd/4.0/).展开更多
<b><span style="font-family:Verdana;">Background:</span></b><span style="font-family:""><span style="font-family:Verdana;"> Traditional medicine h...<b><span style="font-family:Verdana;">Background:</span></b><span style="font-family:""><span style="font-family:Verdana;"> Traditional medicine has employed </span><i><span style="font-family:Verdana;">Azadirachta</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> to treat a variety of ailments. However, there is little information on the use of this </span><span><span style="font-family:Verdana;">plant in Zambia. </span><b><span style="font-family:Verdana;">Objective:</span></b><span style="font-family:Verdana;"> To evaluate the phytochemicals and antibacterial</span></span><span style="font-family:Verdana;"> activity of </span><i><span style="font-family:Verdana;">Azadirachta</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> leaf extracts against </span><i><span style="font-family:Verdana;">Escherichia</span></i> <i><span style="font-family:Verdana;">coli.</span></i> <b><span style="font-family:Verdana;">Materials and Methods:</span></b><span style="font-family:Verdana;"> This was a laboratory-based experimental study in which ethanol and water were used for extraction by maceration. Phytochemical analysis was then done on the leaf extract. Using the disc diffusion method, varying concentrations of </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> aqueous and ethanolic extracts </span><span><span style="font-family:Verdana;">were used to test the antibacterial activity of </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i> <i><span style="font-family:Verdana;">against</span></i> <i><span style="font-family:Verdana;">Escherichia</span></i> <i><span style="font-family:Verdana;">co</span></i></span><i><span style="font-family:Verdana;">li</span></i><span style="font-family:Verdana;">. The sensitivity of the tested microorganisms to aqueous and ethanolic </span><span><span style="font-family:Verdana;">leaf extracts was shown by zones of inhibition after incubation. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">The</span></span><span style="font-family:Verdana;"> phytochemical screening of the </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> leaves revealed the presence of phenolics and tannins in both the ethanol and aqueous extract. Saponins, flavonoids and alkaloids were only present in the aqueous extract. While steroids were only present in the ethanol extract. The antibacterial activity of </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> leaves extract was determined by zones of inhibition which showed that both aqueous and ethanol extracts had activity against </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">coli</span></i><span style="font-family:Verdana;">. The Minimum Inhibitory Concentration was determined at 10 mg/mL for the aqueous extract and 20 mg/mL for the ethanol extract. The zones of inhibition increased with concentration. </span><b><span style="font-family:Verdana;">Conclusion: </span></b><span style="font-family:Verdana;">The extracts of </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> displayed antibacterial activity against </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">coli</span></i><span style="font-family:Verdana;"> in a dose-dependent manner. Comparatively, the aqueous extract produced better antibacterial properties against </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">coli</span></i><span style="font-family:Verdana;"> than the ethanolic extract.展开更多
The influence of substituting V for Fe on the magnetic properties of amorphous Fe_(90-x)V_(x)Zr_(10) alloys have been systematically investigated.A clear max-ium in Curie temperature,a decrease of high-field susceptib...The influence of substituting V for Fe on the magnetic properties of amorphous Fe_(90-x)V_(x)Zr_(10) alloys have been systematically investigated.A clear max-ium in Curie temperature,a decrease of high-field susceptibility and magnetic moment with addition of V was observed.展开更多
After a brief, critical review of the leading explanations proposed for the small but important subset of radio galaxies showing an X-shaped morphology （XRGs） we propose a generalized model, based on the jet-shell i...After a brief, critical review of the leading explanations proposed for the small but important subset of radio galaxies showing an X-shaped morphology （XRGs） we propose a generalized model, based on the jet-shell interaction and spin- flip hypotheses. The most popular scenarios for this intriguing phenomenon invoke either hydrodynamical backflows and over-pressured cocoons or rapid jet reorienta- tions, presumably from the spin-flips of central engines following the mergers of pairs of galaxies, each of which contains a supermassive black hole. We confront these models with a number of key observations, and thus argue that none of the models is capable of explaining the entire range of the salient observational properties of XRGs, although some of the arguments raised in the literature against the spin-flip scenario are probably not tenable. We then propose a new scenario which also involves galac- tic mergers but would allow the spin of the central engine to maintain its direction. Motivated by detailed multi-band observations of the nearest radio galaxy, Centaurus A, this new model emphasizes the role of the interactions between the jets and the shells of stars and gas that form and rotate around the merged galaxy and can cause temporary deflections of the jets, occasionally giving rise to an X-shaped radio struc- ture. Although each model is likely to be relevant to a subset of XRGs, the bulk of the evidence indicates that most of them are best explained by the jet-shell interaction or spin-flip hypotheses.展开更多
Thermoelectric devices enable direct conversion between thermal and electrical energy.Recent studies have indicated that the thin film/substrate heterostructure is effective in achieving high thermoelectric performanc...Thermoelectric devices enable direct conversion between thermal and electrical energy.Recent studies have indicated that the thin film/substrate heterostructure is effective in achieving high thermoelectric performance via decoupling the Seebeck coefficient and electrical conductivity otherwise adversely inter-dependent in homogenous bulk materials.However,the mechanism underlying the thin film/substrate heterostructure thermoelectricity remains unclear.In addition,the power output of the thin film/substrate heterostructure is limited to the nanowatt scale to date,falling short of the practical application requirement.Here,we fabricated the CrN/SrTiO_(3-x) heterostructures with high thermoelectric output power and outstanding thermal stability.By varying the CrN film thickness and the reduction degree of CrN/SrTiO_(3-x) substrate,the optimized power output and the power density have respectively reached 276μWand 10^(8) mW/cm^(2) for the 30 nm CrN film on a highly reduced surface of CrN/SrTiO_(3-x) under a temperature difference of 300 K.The performance enhancement is attributed to the CrN/CrN/SrTiO_(3-x) heterointerface,corroborated by the band bending as revealed by the scanning Kelvin probe microscopy.These results will stimulate further research efforts towards interface thermoelectrics.展开更多
Objective: To study the inhibition effects of estrogen on the production of corticotropin-releasing hormone in human placental cells. Methods: Primary cultured placental cells were treated by ICI182, 780, a complete E...Objective: To study the inhibition effects of estrogen on the production of corticotropin-releasing hormone in human placental cells. Methods: Primary cultured placental cells were treated by ICI182, 780, a complete ER antagonist , and Tamoxifen, an ERa-mixed agonist/antagonist and ERβ antagonist for 24 h. The supernatant was havested for the radioimmunoassay of CRH. Results: 17β-estradiol inhibited the secretion of corticotropin-releasing hormone in human placental (P<0.05). ICI182, 780 stimulated the secretion of corticotropin-releasing hormone in human placental (P<0.05). Conclusion: Estrogen represses the synthesis and secretion of corticotropin-releasing hormone in human placental, which is possibly mediated by ERa.展开更多
In this study,the gravitational deflection angle of photons in the weak field limit(or the weak deflection angle)and shadow cast by the electrically charged and spherically symmetric static Kiselev black hole(BH)in th...In this study,the gravitational deflection angle of photons in the weak field limit(or the weak deflection angle)and shadow cast by the electrically charged and spherically symmetric static Kiselev black hole(BH)in the string cloud background are investigated.The influences of the BH charge Q,quintessence parameterγ,and string cloud parameter a on the weak deflection angle are studied using the Gauss-Bonnet theorem.in addition to studying the influences on the radius of photon spheres and size of the BH shadow in the spacetime geometry of the chargedKiselev BH in string clouds.Moreover,we study the effects of plasma(uniform and non-uniform)on the weak deflection angle and shadow cast by the charged-Kiselev BH surrounded by the clouds of strings.In the presence of a uniform/nonuniform plasma medium,an increase in the string cloud parameter a increases the deflection angleα.In contrast,a decrease in the BH charge Q decreases the deflection angle.Further,we observe that an increase in the BH charge Q causes a decrease in the size of the shadow of the BH.We notice that,with an increase in the values of the parametersγand a,the size of the BH shadow increases,and therefore,the intensity of the gravitational field around the charged-Kiselev BH in string clouds increases.Thus,the gravitational field of the charged-Kiselev BH in the string cloud background is stronger than the field produced by the pure Reissner-Nordstrom BH.Moreover,we use the data released by the Event Horizon Telescope(EHT)collaboration,for the supermassive BHs M87*and Sgr A*,to obtain constraints on the values of the parametersγand a.展开更多
Synthesis, structure and magnetic properties of Ru doped perovskite structured manganite La0.5Sr0.5MnO3 were investigated experimentally. A hydrothermal method was used for the preparation of the samples. A high-tempe...Synthesis, structure and magnetic properties of Ru doped perovskite structured manganite La0.5Sr0.5MnO3 were investigated experimentally. A hydrothermal method was used for the preparation of the samples. A high-temperature annealing process was also employed to make a comparison. A slightly enhancement of the unit cell volume was observed with the increase of Ru concentration. Scanning electron microscopy shows that the materials are made up of cube-shaped particles with dimension of several micrometers. Importantly, it is found that both the Curie temperature TC and saturation moment can be reduced by Ru doping. The value of coercive field is not affected by the introduction of Ru.展开更多
Google Page Rank is a prevalent algorithm for ranking the significance of nodes or websites in a network,and a recent quantum counterpart for Page Rank algorithm has been raised to suggest a higher accuracy of ranking...Google Page Rank is a prevalent algorithm for ranking the significance of nodes or websites in a network,and a recent quantum counterpart for Page Rank algorithm has been raised to suggest a higher accuracy of ranking comparing to Google Page Rank.The quantum Page Rank algorithm is essentially based on quantum stochastic walks and can be expressed using Lindblad master equation,which,however,needs to solve the Kronecker products of an O(N^(4))dimension and requires severely large memory and time when the number of nodes N in a network increases above 150.Here,we present an efficient solver for quantum Page Rank by using the Runge-Kutta method to reduce the matrix dimension to O(N^(2))and employing Tensor Flow to conduct GPU parallel computing.We demonstrate its performance in solving quantum stochastic walks on Erdos-Rényi graphs using an RTX 2060 GPU.The test on the graph of 6000 nodes requires a memory of 5.5 GB and time of 223 s,and that on the graph of 1000 nodes requires 226 MB and 3.6 s.Compared with QSWalk,a currently prevalent Mathematica solver,our solver for the same graph of 1000 nodes reduces the required memory and time to only 0.2%and 0.05%.We apply the solver to quantum Page Rank for the USA major airline network with up to 922 nodes,and to quantum stochastic walk on a glued tree of 2186 nodes.This efficient solver for large-scale quantum Page Rank and quantum stochastic walks would greatly facilitate studies of quantum information in real-life applications.展开更多
Undetected-photon imaging allows for objects to be imaged in wavelength regions where traditional components are unavailable. Although first demonstrated using quantum sources, recent work has shown that the technique...Undetected-photon imaging allows for objects to be imaged in wavelength regions where traditional components are unavailable. Although first demonstrated using quantum sources, recent work has shown that the technique also holds with classical beams. To date, however, all the research in this area has exploited parametric downconversion processes using bulk nonlinear crystals within free-space systems. Here, we demonstrate undetectedphoton-based imaging using light generated via stimulated four-wave mixing within highly nonlinear silicon fiber waveguides. The silicon fibers have been tapered to have a core diameter of915 nm to engineer the dispersion and reduce the insertion losses, allowing for tight mode confinement over extended lengths to achieve practical nonlinear conversion efficiencies(-30 dB) with modest pump powers(48 m W). Both amplitude and phase images are obtained using classically generated light, confirming the high degree of spatial and phase correlation of our system. The high powers(>10 nW) and long coherence lengths(>4 km) associated with our large fiber-based system result in high contrast and stable images.展开更多
The numerical simulation is used in this work to study the nearfield radiation pressure of a piston projector, the smooth effect on the pressure field by using a 'big' receiver and the influence of the nearfie...The numerical simulation is used in this work to study the nearfield radiation pressure of a piston projector, the smooth effect on the pressure field by using a 'big' receiver and the influence of the nearfield and in the transition region on measurement of sound absorption coefficient. The result indicates that the big error would appear when using usual absorption coefficient measurement method. According to the reason causing the error, the method eliminating nearfield effect (MENE) is proposed and some digital results are given for a / λ= 3, 9 and b = 0, 0.5a, a (a and b are the transducer and receiver radii respectively). The calculation results show that the method not only widens measurement range in nearfield, but also gives accurate results.展开更多
We present the development and characterization of a high-stability,multi-material,multi-thickness tape-drive target for laser-driven acceleration at repetition rates of up to 100 Hz.The tape surface position was meas...We present the development and characterization of a high-stability,multi-material,multi-thickness tape-drive target for laser-driven acceleration at repetition rates of up to 100 Hz.The tape surface position was measured to be stable on the sub-micrometre scale,compatible with the high-numerical aperture focusing geometries required to achieve relativistic intensity interactions with the pulse energy available in current multi-Hz and near-future higher repetition-rate lasers(>kHz).Long-term drift was characterized at 100 Hz demonstrating suitability for operation over extended periods.The target was continuously operated at up to 5 Hz in a recent experiment for 70,000 shots without intervention by the experimental team,with the exception of tape replacement,producing the largest data-set of relativistically intense laser–solid foil measurements to date.This tape drive provides robust targetry for the generation and study of high-repetitionrate ion beams using next-generation high-power laser systems,also enabling wider applications of laser-driven proton sources.展开更多
基金This work was financially supported by the National Natural Science Foundation of China (No.50402024)the Natural Science Foundation of Gansu Province (No.ZS041-A25-033).
文摘Vanadium oxide nanotubes were synthesized by hydrothermal treatment from V2O5·nH2O sols as precursor and dodecylamine as structure-directing template. The morphology and structure of the nanotubes were characterized by SEM, TEM, XRD, TG-DTA and FTIR. The experimental results reveal that the duration of the hydrothermal treatment is of importance for obtaining VOx-NTs which have a layered structure. TG-DTA study indicates that V5+ cations in nanotubes are partially reduced to V4+ cations. The results from FTIR spectra indicate the difference in V-O vibrations between before and after hydrothermal treatment. From the results, it suggests that during hydrothermal treatment, the rearrangement of the vanadium oxide structure leads to the formation of VOx nanotubes from lamellar structure because of the presence of V4+ species.
基金supported by research funds allocated to the following departments at the University of Verona:Neurosciences,Biomedicine and Movement Sciences,and Diagnostic and Public Health
文摘Background:Smokeless tobacco is widely used by athletes to enhance performance.Nicotine is a central nervous system stimulant and acts on cardiocirculatory and metabolic systems,involving tissue blood flow and circulatory vasoreactivity.The aim of this study was to investigate the effects of the oral smokeless tobacco(Swedish snus(SS))on the perception of fatigue and time to exhaustion(TTE)during moderate-intensity aerobic exercise.Methods:Fourteen healthy non-tobacco male users were recruited for a double-blind,controlled crossover design(SS vs.snus placebo(SP)).Subjects were tested for 3 sessions:experimental session 1(Exp 1)consisted of an incremental test to determine the maximal aerobic power out-put(Wmax),whereas Exp2 and Exp3 consisted of exercising at 65%Wmax until exhaustion in SS or SP conditions.During Exp2 and Exp3,muscle and cerebral oxygenation was assessed by means of near-infrared spectroscopy,and the rating of perceived exertion(RPE)was recorded.Results:Comparing SS with SP tests,significant differences(p〈0.05)were found in the values of cerebral(-3%)and muscular tissues oxygenation(-4%)in the first 30 min of exercise.The RPE values were not significantly different between the 2 conditions(SS vs.SP).No significant difference was found in TTE(SS:54.25±21.84 min;SP:50.01±17.03 min).Conclusion:This study showed that muscular and cerebral oxygenation increased significantly with snus administration during an endurance exercise until exhaustion,but this did not affect fatigue perception and TTE.The results showed that snus could not be considered an ergogenic substance in non-tobacco users.2018 Published by Elsevier B.V.on behalf of Shanghai University of Sport.This is an open access article under the CC BY-NC-ND license.(http://creativecommons.org/licenses/by-nc-nd/4.0/).
文摘<b><span style="font-family:Verdana;">Background:</span></b><span style="font-family:""><span style="font-family:Verdana;"> Traditional medicine has employed </span><i><span style="font-family:Verdana;">Azadirachta</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> to treat a variety of ailments. However, there is little information on the use of this </span><span><span style="font-family:Verdana;">plant in Zambia. </span><b><span style="font-family:Verdana;">Objective:</span></b><span style="font-family:Verdana;"> To evaluate the phytochemicals and antibacterial</span></span><span style="font-family:Verdana;"> activity of </span><i><span style="font-family:Verdana;">Azadirachta</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> leaf extracts against </span><i><span style="font-family:Verdana;">Escherichia</span></i> <i><span style="font-family:Verdana;">coli.</span></i> <b><span style="font-family:Verdana;">Materials and Methods:</span></b><span style="font-family:Verdana;"> This was a laboratory-based experimental study in which ethanol and water were used for extraction by maceration. Phytochemical analysis was then done on the leaf extract. Using the disc diffusion method, varying concentrations of </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> aqueous and ethanolic extracts </span><span><span style="font-family:Verdana;">were used to test the antibacterial activity of </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i> <i><span style="font-family:Verdana;">against</span></i> <i><span style="font-family:Verdana;">Escherichia</span></i> <i><span style="font-family:Verdana;">co</span></i></span><i><span style="font-family:Verdana;">li</span></i><span style="font-family:Verdana;">. The sensitivity of the tested microorganisms to aqueous and ethanolic </span><span><span style="font-family:Verdana;">leaf extracts was shown by zones of inhibition after incubation. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">The</span></span><span style="font-family:Verdana;"> phytochemical screening of the </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> leaves revealed the presence of phenolics and tannins in both the ethanol and aqueous extract. Saponins, flavonoids and alkaloids were only present in the aqueous extract. While steroids were only present in the ethanol extract. The antibacterial activity of </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> leaves extract was determined by zones of inhibition which showed that both aqueous and ethanol extracts had activity against </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">coli</span></i><span style="font-family:Verdana;">. The Minimum Inhibitory Concentration was determined at 10 mg/mL for the aqueous extract and 20 mg/mL for the ethanol extract. The zones of inhibition increased with concentration. </span><b><span style="font-family:Verdana;">Conclusion: </span></b><span style="font-family:Verdana;">The extracts of </span><i><span style="font-family:Verdana;">A.</span></i> <i><span style="font-family:Verdana;">indica</span></i><span style="font-family:Verdana;"> displayed antibacterial activity against </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">coli</span></i><span style="font-family:Verdana;"> in a dose-dependent manner. Comparatively, the aqueous extract produced better antibacterial properties against </span><i><span style="font-family:Verdana;">E.</span></i> <i><span style="font-family:Verdana;">coli</span></i><span style="font-family:Verdana;"> than the ethanolic extract.
文摘The influence of substituting V for Fe on the magnetic properties of amorphous Fe_(90-x)V_(x)Zr_(10) alloys have been systematically investigated.A clear max-ium in Curie temperature,a decrease of high-field susceptibility and magnetic moment with addition of V was observed.
文摘After a brief, critical review of the leading explanations proposed for the small but important subset of radio galaxies showing an X-shaped morphology （XRGs） we propose a generalized model, based on the jet-shell interaction and spin- flip hypotheses. The most popular scenarios for this intriguing phenomenon invoke either hydrodynamical backflows and over-pressured cocoons or rapid jet reorienta- tions, presumably from the spin-flips of central engines following the mergers of pairs of galaxies, each of which contains a supermassive black hole. We confront these models with a number of key observations, and thus argue that none of the models is capable of explaining the entire range of the salient observational properties of XRGs, although some of the arguments raised in the literature against the spin-flip scenario are probably not tenable. We then propose a new scenario which also involves galac- tic mergers but would allow the spin of the central engine to maintain its direction. Motivated by detailed multi-band observations of the nearest radio galaxy, Centaurus A, this new model emphasizes the role of the interactions between the jets and the shells of stars and gas that form and rotate around the merged galaxy and can cause temporary deflections of the jets, occasionally giving rise to an X-shaped radio struc- ture. Although each model is likely to be relevant to a subset of XRGs, the bulk of the evidence indicates that most of them are best explained by the jet-shell interaction or spin-flip hypotheses.
基金supported by Liaoning Revitalization Talents Program (No. XLYC1807209)Dalian Institute of Chemical Physics (DICP I202037)the National Natural Science Foundation of China (Grant Nos. 21625304, 22022205).
文摘Thermoelectric devices enable direct conversion between thermal and electrical energy.Recent studies have indicated that the thin film/substrate heterostructure is effective in achieving high thermoelectric performance via decoupling the Seebeck coefficient and electrical conductivity otherwise adversely inter-dependent in homogenous bulk materials.However,the mechanism underlying the thin film/substrate heterostructure thermoelectricity remains unclear.In addition,the power output of the thin film/substrate heterostructure is limited to the nanowatt scale to date,falling short of the practical application requirement.Here,we fabricated the CrN/SrTiO_(3-x) heterostructures with high thermoelectric output power and outstanding thermal stability.By varying the CrN film thickness and the reduction degree of CrN/SrTiO_(3-x) substrate,the optimized power output and the power density have respectively reached 276μWand 10^(8) mW/cm^(2) for the 30 nm CrN film on a highly reduced surface of CrN/SrTiO_(3-x) under a temperature difference of 300 K.The performance enhancement is attributed to the CrN/CrN/SrTiO_(3-x) heterointerface,corroborated by the band bending as revealed by the scanning Kelvin probe microscopy.These results will stimulate further research efforts towards interface thermoelectrics.
基金Supported by National Natural Science Foundation of China(No.39870300)
文摘Objective: To study the inhibition effects of estrogen on the production of corticotropin-releasing hormone in human placental cells. Methods: Primary cultured placental cells were treated by ICI182, 780, a complete ER antagonist , and Tamoxifen, an ERa-mixed agonist/antagonist and ERβ antagonist for 24 h. The supernatant was havested for the radioimmunoassay of CRH. Results: 17β-estradiol inhibited the secretion of corticotropin-releasing hormone in human placental (P<0.05). ICI182, 780 stimulated the secretion of corticotropin-releasing hormone in human placental (P<0.05). Conclusion: Estrogen represses the synthesis and secretion of corticotropin-releasing hormone in human placental, which is possibly mediated by ERa.
基金Partly supported by the Uzbekistan Ministry for Innovative Development(FZ-20200929344 and F-FA-2021-510)supported by Postdoctoral Fellowship of Zhejiang Normal University(ZC304022919)。
文摘In this study,the gravitational deflection angle of photons in the weak field limit(or the weak deflection angle)and shadow cast by the electrically charged and spherically symmetric static Kiselev black hole(BH)in the string cloud background are investigated.The influences of the BH charge Q,quintessence parameterγ,and string cloud parameter a on the weak deflection angle are studied using the Gauss-Bonnet theorem.in addition to studying the influences on the radius of photon spheres and size of the BH shadow in the spacetime geometry of the chargedKiselev BH in string clouds.Moreover,we study the effects of plasma(uniform and non-uniform)on the weak deflection angle and shadow cast by the charged-Kiselev BH surrounded by the clouds of strings.In the presence of a uniform/nonuniform plasma medium,an increase in the string cloud parameter a increases the deflection angleα.In contrast,a decrease in the BH charge Q decreases the deflection angle.Further,we observe that an increase in the BH charge Q causes a decrease in the size of the shadow of the BH.We notice that,with an increase in the values of the parametersγand a,the size of the BH shadow increases,and therefore,the intensity of the gravitational field around the charged-Kiselev BH in string clouds increases.Thus,the gravitational field of the charged-Kiselev BH in the string cloud background is stronger than the field produced by the pure Reissner-Nordstrom BH.Moreover,we use the data released by the Event Horizon Telescope(EHT)collaboration,for the supermassive BHs M87*and Sgr A*,to obtain constraints on the values of the parametersγand a.
基金supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No. 2015187)the National Natural Science Foundation of China (Grant No. 11204338).
文摘Synthesis, structure and magnetic properties of Ru doped perovskite structured manganite La0.5Sr0.5MnO3 were investigated experimentally. A hydrothermal method was used for the preparation of the samples. A high-temperature annealing process was also employed to make a comparison. A slightly enhancement of the unit cell volume was observed with the increase of Ru concentration. Scanning electron microscopy shows that the materials are made up of cube-shaped particles with dimension of several micrometers. Importantly, it is found that both the Curie temperature TC and saturation moment can be reduced by Ru doping. The value of coercive field is not affected by the introduction of Ru.
基金supported by the National Key R&D Program of China(2019YFA0308700,and 2017YFA0303700)the National Natural Science Foundation of China(61734005,11761141014,11690033)+3 种基金the Science and Technology Commission of Shanghai Municipality(STCSM)(17JC1400403)the Shanghai Municipal Education Commission(SMEC)(2019SHZDZX01,2017-01-07-0002-E00049)supported by the National Natural Science Foundation of China(11904229)China Postdoctoral Science Foundation(2019T120334)。
文摘Google Page Rank is a prevalent algorithm for ranking the significance of nodes or websites in a network,and a recent quantum counterpart for Page Rank algorithm has been raised to suggest a higher accuracy of ranking comparing to Google Page Rank.The quantum Page Rank algorithm is essentially based on quantum stochastic walks and can be expressed using Lindblad master equation,which,however,needs to solve the Kronecker products of an O(N^(4))dimension and requires severely large memory and time when the number of nodes N in a network increases above 150.Here,we present an efficient solver for quantum Page Rank by using the Runge-Kutta method to reduce the matrix dimension to O(N^(2))and employing Tensor Flow to conduct GPU parallel computing.We demonstrate its performance in solving quantum stochastic walks on Erdos-Rényi graphs using an RTX 2060 GPU.The test on the graph of 6000 nodes requires a memory of 5.5 GB and time of 223 s,and that on the graph of 1000 nodes requires 226 MB and 3.6 s.Compared with QSWalk,a currently prevalent Mathematica solver,our solver for the same graph of 1000 nodes reduces the required memory and time to only 0.2%and 0.05%.We apply the solver to quantum Page Rank for the USA major airline network with up to 922 nodes,and to quantum stochastic walk on a glued tree of 2186 nodes.This efficient solver for large-scale quantum Page Rank and quantum stochastic walks would greatly facilitate studies of quantum information in real-life applications.
基金Engineering and Physical Sciences Research Council(EP/P000940/1)Norges Forskningsrad+2 种基金J.E.Sirrine Textile FoundationNatural Sciences and Engineering Research Council of CanadaNational Natural Science Foundation of China(62175080)
文摘Undetected-photon imaging allows for objects to be imaged in wavelength regions where traditional components are unavailable. Although first demonstrated using quantum sources, recent work has shown that the technique also holds with classical beams. To date, however, all the research in this area has exploited parametric downconversion processes using bulk nonlinear crystals within free-space systems. Here, we demonstrate undetectedphoton-based imaging using light generated via stimulated four-wave mixing within highly nonlinear silicon fiber waveguides. The silicon fibers have been tapered to have a core diameter of915 nm to engineer the dispersion and reduce the insertion losses, allowing for tight mode confinement over extended lengths to achieve practical nonlinear conversion efficiencies(-30 dB) with modest pump powers(48 m W). Both amplitude and phase images are obtained using classically generated light, confirming the high degree of spatial and phase correlation of our system. The high powers(>10 nW) and long coherence lengths(>4 km) associated with our large fiber-based system result in high contrast and stable images.
文摘The numerical simulation is used in this work to study the nearfield radiation pressure of a piston projector, the smooth effect on the pressure field by using a 'big' receiver and the influence of the nearfield and in the transition region on measurement of sound absorption coefficient. The result indicates that the big error would appear when using usual absorption coefficient measurement method. According to the reason causing the error, the method eliminating nearfield effect (MENE) is proposed and some digital results are given for a / λ= 3, 9 and b = 0, 0.5a, a (a and b are the transducer and receiver radii respectively). The calculation results show that the method not only widens measurement range in nearfield, but also gives accurate results.
基金Special thanks go to the staff at the Central Laser Facility who provided laser operational support,mechanical and electrical support and computational and administrative support throughout the experiment.We acknowledge funding from UK STFC,Grant Nos.ST/P002021/1 and ST/V001639/1U.S.DOE Office of Science,Fusion Energy Sciences under FWP No.100182+2 种基金in part by the National Science Foundation under Grant No.1632708G.D.G.acknowledges support from the DOE NNSA SSGF program under DE-NA0003960This work has been partially supported by the project Advanced Research Using High-intensity Laser-produced Photons and Particles(CZ.02.1.01/0.0/0.0/16_019/0000789)from the European Regional Development Fund(ADONIS).
文摘We present the development and characterization of a high-stability,multi-material,multi-thickness tape-drive target for laser-driven acceleration at repetition rates of up to 100 Hz.The tape surface position was measured to be stable on the sub-micrometre scale,compatible with the high-numerical aperture focusing geometries required to achieve relativistic intensity interactions with the pulse energy available in current multi-Hz and near-future higher repetition-rate lasers(>kHz).Long-term drift was characterized at 100 Hz demonstrating suitability for operation over extended periods.The target was continuously operated at up to 5 Hz in a recent experiment for 70,000 shots without intervention by the experimental team,with the exception of tape replacement,producing the largest data-set of relativistically intense laser–solid foil measurements to date.This tape drive provides robust targetry for the generation and study of high-repetitionrate ion beams using next-generation high-power laser systems,also enabling wider applications of laser-driven proton sources.
