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Explosive-Emission Plasma Dynamics in ion Diode in Double-Pulse Mode

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Plasma Science and Technology 2011年第6期13卷 698-701页

作者： alexander i.PUSHKAREV Yulia i.iSAKOVA Tomsk Polytechnic University

The results of an experimental investigation of explosive-emission plasma dynamics in an ion diode with self-magnetic insulation are presented. The investigations were accomplished at the TEMP-4M accelerator set in a mode of double pulse formation. Plasma behaviour in the anode-cathode gap was analyzed according to both the current-voltage characteristics of the diode （time resolution of 0.5 ns） and thermal imprints on a target （spatial resolution of 0.8 mm）. it was shown that when plasma formation at the potential electrode was complete, and up until the second （positive） pulse, the explosive-emission plasma expanded across the anode-cathode gap with a speed of 1.3±0.2 cm/μs. After the voltage polarity at the potential electrode was reversed （second pulse）, the plasma erosion in the anode-cathode gap （similar to the effect of a plasma opening switch） occurred. During the generation of an ion beam the size of the anode-cathode gap spacing was determined by the thickness of the plasma layer on the potential electrode and the layer thickness of the electrons drifting along the grounded electrode.

关键词： ion beams graphite cathodes plasma speed self-magnetic insulation

A simple semiempirical model for the static polarizability of electronically excited atoms and molecules

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Chinese Physics B 2023年第4期32卷 290-301页

作者： alexander S Sharipov Alexey V Pelevkin Boris i Loukhovitski Central institute of Aviation Motors Aviamotornaya 2Moscow 111116Russia

We present a semiempirical analytical model for the static polarizability of electronically excited atoms and molecules,which requires very few readily accessible input data,including the ground-state polarizability,elemental composition,ionization potential,and spin multiplicities of excited and ground *** very simple model formulated in a semiclassical framework is based on a number of observed trends in polarizability of electronically excited *** adjust the model,both accurate theoretical predictions and reliable measurements previously reported elsewhere for a broad range of multielectron species in the gas phase are *** some representative compounds of general concern that have not yet attracted sufficient research interest,the results of our multireference second-order perturbation theory calculations are additionally *** show that the model we developed has reasonable(given the considerable uncertainties in the reference data)accuracy in predicting the static polarizability of electronically excited species of arbitrary size and excitation *** findings can be useful for many applications,where there is a need for inexpensive and quick assessments of the static gas-phase polarizability of excited electronic states,in particular,when building the complex nonequilibrium kinetic models to describe the observed optical refractivity(dielectric permittivity)of nonthermal reacting gas flows.

关键词： polarizability electronic excitation semiempirical model quantum chemistry

A simple semiempirical model for the static polarizability of ions

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Chinese Physics B 2023年第8期32卷 32-45页

作者： alexander S Sharipov Boris i Loukhovitski Central institute of Aviation Motors Aviamotornaya 2Moscow 111116Russia

A concise analytical model for the static dipole polarizability of ionized atoms and molecules is created for the first *** input,it requires,alongside the polarizability of neutral counterpart of a given ion,only the charge and elemental *** physically motivated semiempirical model is based on a number of established regularities in polarizability of charged monatomic and polyatomic *** order to adjust it,the results of quantum chemistry calculations and gas-phase measurements available for a broad range of ionized multielectron species are *** counteract the appreciable bias in the literature data toward polarizability of monoatomic ions,for some molecular ions of general concern the results of the authors'own density functional theory calculations are additionally invoked.A total of 541 data points are used to optimize the *** is demonstrated that the model we suggested has reasonable(given the substantial uncertainties of the reference data)accuracy in predicting the static isotropic polarizability of arbitrarily charged ions of any size and atomic *** resulting polarizability estimates are found to achieve a coefficient of determination of 0.93 for the assembled data *** created analytic tool is universally applicable and might be advantageous for some applications where there is an urgent need for rapid low-cost evaluation of the static gas-phase polarizability of ionized atoms and *** is especially relevant to constructing the complex models of nonequilibrium chemical kinetics aimed at precisely describing the observable refractive index(dielectric permittivity)of plasma *** data sets that support the findings of this study are openly available in Science Data Bank at https://***/10.57760/sciencedb.07526.

关键词： polarizability ions semiempirical model quantum chemistry

The role of Eph receptors in lens function and disease

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Science China(Life Sciences) 2012年第5期55卷 434-443页

作者： SON alexander i. PARK Jeong Eun Department of Chemical Biology Ernest Mario School of PharmacyRutgersThe State University of New Jersey

Cataract is the single largest contributor to blindness in the world,with the disease having a strong genetic *** recent years the Eph family of receptor tyrosine kinases has been identified as a key regulator in lens... 详细信息

关键词： cataract lens EphA2 ephrin-A5

Dielectric tunability of magnetic properties in orthorhombic ferromagnetic monolayer CrSBr

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npj Computational Materials 2023年第1期9卷 1514-1523页

作者： alexander N.Rudenko Malte Rösner Mikhail i.Katsnelson Radboud University Institute for Molecules and MaterialsHeijendaalseweg 1356525AJ NijmegenThe Netherlands

Monolayer CrSBr is a recently discovered semiconducting spin-3/2 ferromagnet with a Curie temperature of around 146 *** contrast to many other known 2D magnets,the orthorhombic lattice of CrSBr gives rise to spatial anisotropy of magnetic excitations within the 2D *** magnetic anisotropy and considerable magnetic dipolar interactions in CrSBr challenge its theoretical description in terms of spin ***,we employ a Green’s function formalism combined with first-principles calculations to study the magnetic properties of monolayer CrSBr in different regimes of surrounding dielectric *** the free-standing limit,the system is close to an easy-plane magnet,whose long-range ordering is partially *** the contrary,in the regime of large external screening,monolayer CrSBr behaves like an easy-axis ferromagnet with more stable magnetic *** findings suggest that anisotropic layered magnets form a potentially promising platform for studying the effects of substrate screening on magnetic ordering in 2D.

关键词： monolayer orthorhombic anisotropy

Metastability effects in strained and stressed SrTiO_(3) films

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Journal of Advanced Dielectrics 2016年第3期6卷 5-16页

作者： alexander i.Lebedev Physics Department Moscow State University Leninskie GoryMoscow 119991Russia

The sequence of ground states for SrTiO_(3) film subjected to epitaxial strain as well as to mechanical stress along the[001]and[110]axes is calculated from first principles within the density functional *** the fixed-strain boundary conditions,an increase in the lattice parameter of a substrate results in the i4cm→i4/mcm→ima2→Cm→Fmm2→ima2(ii)sequence of ground *** the fixed-stress boundary conditions,the phase sequence is different and depends on how the stress is *** is revealed that the simultaneous presence of competing ferroelectric and antiferrodistortive instabilities in SrTiO_(3) gives rise to the appearance of metastable phases,whose number increases dramatically under the fixed-stress *** the metastable phases,the octahedral rotation patterns are shown to differ substantially from those in the ground *** is suggested that in systems with competing instabilities,each polar phase has its optimal octahedral rotation pattern which stabilizes this phase and creates a potential barrier preventing this phase to be transformed into other structures.

关键词： Ferroelectricity competing instabilities strain effects metastable phases strontium titanate

Numerical investigation of full scale coaxial main rotor aerodynamics in hover and vertical descent

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Chinese Journal of Aeronautics 2021年第5期34卷 666-683页

作者： Pavel V.MAKEEV Yuri M.iGNATKiN alexander i.SHOMOV Department of Helicopter Design Moscow Aviation Institute(National Research University)Moscow 125993Russia

The original free vortex wake model was used for numerical *** of the aerodynamic characteristics in hover and vertical descent modes in the range of vertical descent speed of 0–30 m/s including the Vortex Ring State(VRS)area was *** calculations were carried out under the condition of variable blade pitch angle values providing a fixed timeaverage thrust *** data of free vortex wake shapes,flow structures,and velocity fields were obtained and *** time-dependences of the rotor’s thrust and torque coefficients were obtained and *** obtained data allows determining the boundaries of the VRS area by various criteria such as rotor thrust and torque pulsations,growth of rotor power consumption relative to the hover,growth of rotor induced velocities relative to the hover,and growth of the required rotor blade pitch angles *** results of the study are compared with experimental and calculated data of other authors and can significantly supplement the available results of experimental and computational studies in this area.

关键词： Aerodynamic characteristics Coaxial rotor Free wake model Hover and vertical descent Vortex ring state mode

Delayed assessment and eager adoption of laparoscopic cholecystectomy:implications for developing surgical technologies

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World Journal of Gastroenterology 2010年第33期16卷 4115-4122页

作者： alexander C Allori i Michael Leitman Elizabeth Heitman Department of Surgery Beth Israel Medical Center Center for Biomedical Ethics and Society Vanderbilt University Medical Center

Despite the prevailing emphasis in the medical literature on establishing evidence,many changes in the practice of surgery have not been achieved using proper evidence-based *** paper examines the adoption of laparoscopic cholecystectomy(LC)into regular use for the treatment of cholecystitis and the process of its acceptance,focusing on the limited role of technology assessment in its appraisal.A review of the published medical literature concerning LC was *** 3000 studies of LC have been conducted since 1985,and there have been nearly 8500 publications to *** LC was adopted enthusiastically into practice,the results of outcome studies generally showed that it compared favorably with the traditional,open cholecystectomy with regard to mortality,complications,and length of hospital ***,despite the rapid general agreement on surgical technique,efficacy,and appropriateness,there remained lingering doubts about safety,outcomes,and cost of the procedure that suggested that essential research questions were ignored even as the procedure became *** LC as a case study,there are important lessons to be learned about the need for important guidelines for surgical innovation and the adoption of minimally invasive surgical techniques into current clinical and surgical *** highlight one recent example,natural orifice transluminal endoscopic surgery and how necessary it is to properly evaluate this new technology before it is accepted as a safe and effective surgical option.

关键词： Laparoscopy Endoscopy Minimally invasive surgery Cholecystectomy Natural orifice transluminal endoscopic surgery Evidence-based medicine Technol- ogy assessment Comparative effectiveness research

A Statistical Study of Magnetic Flux Emergence in Solar Active Regions Prior to Strongest Flares

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Research in Astronomy and Astrophysics 2024年第4期24卷 147-160页

作者： alexander S.Kutsenko Valentina i.Abramenko Andrei A.Plotnikov Crimean Astrophysical Observatory p/o NauchnyCrimea298409Russia

Using the data on magnetic field maps and continuum intensity for Solar Cycles 23 and 24,we explored 100 active regions(ARs)that produced M5.0 or stronger *** focus on the presence/absence of the emergence of magnetic flux in these ARs 2-3 days before the strong flare *** found that 29 ARs in the sample emerged monotonically amidst quiet-Sun.A major emergence of a new magnetic flux within a pre-existing AR yielding the formation of a complex flare-productive configuration was observed in another 24 *** 30 ARs,an insignificant(in terms of the total magnetic flux of pre-existing AR)emergence of a new magnetic flux within the pre-existing magnetic configuration was observed;for some of them the emergence resulted in a formation of a configuration with a small δ-sunspot;11 out of 100 ARs exhibited no signatures of magnetic flux emergence during the entire interval of *** six cases the emergence was in progress when the AR appeared on the Eastern limb,so that the classification and timing of emergence were not *** conclude that the recent flux emergence is not a necessary and/or sufficient condition for strong flaring of an *** flux emergence rate of flare-productive ARs analyzed here was compared with that of flare-quiet ARs analyzed in our previous *** revealed that the flare-productive ARs tend to display faster emergence than the flare-quiet ones do.

关键词： Sun:activity Sun:flares Sun:magnetic fields