DIRECTED SEARCH FOR NOVEL Α-GLUCOSIDASE INHIBITORS USING STRUCTURE SIMILARITY WITH TESTED SUBSTANCES

56-5

Quadrilateral element in mixed FEM for analysis of thin shells of revolution

The purpose of study is to develop an algorithm for the analysis of thin shells of revolution based on the hybrid formulation of finite element method in two dimensions using a quadrilateral fragment of the middle surface as a discretization element. Nodal axial forces and moments, as well as components of the nodal displacement vector were selected as unknown variables. The number of unknowns in each node of the four-node discretization element reaches nine: six force variables and three kinematic variables. To obtain the flexibility matrix and the nodal forces vector, a modified Reissner functional was used, in which the total specific work of stresses is represented by the specific work of membrane forces and bending moments of the middle surface on its membrane and bending strains, and the specific additional work is determined by the specific work of membrane forces and bending moments of the middle surface. Bilinear shape functions of local coordinates were used as approximating expressions for both force and displacement unknowns. The dimensions of the flexibility matrix of the four-node discretization element were found to be 36×36. The solution of benchmark problem of analyzing a truncated ellipsoid of revolution loaded with internal pressure showed sufficient accuracy in calculating the strength parameters of the studied shell

THE FINITE ELEMENTS OF A QUADRILATED SHAPE FOR ANALYSIS OF SHELLS TAKING INTO CONSIDERATION A DISPLACEMENT OF A BODY WITH RIGID BODY MODES

On the basis of a curvilinear quadrilated finite element the new mode of approximation of fields of displacements is realized, which essence consists that at a stage of approximation of interior magnitudes through nodal unknown of a finite element accept not separate components of a vector of displacement and their derivative, and immediately vector of displacement of nodal points of a finite element and its derivative. On an example of account of an equalizer loaded by interior pressure with presence of constructional displacement as rigid body is shown. That use of the developed algorithm solves a well-known problem FEM - account of displacement of finite element as rigid body

13C NMR spectroscopy of peroxide derivatives of cyclanes and cyclic peroxides

1. The13C NMR spectra of peroxide derivatives of cyclanes and cyclic peroxides have been investigated. 2. Replacement of the exocyclic OH group by OOH for saturated cyclic systems leads to a displacement of the signals from the α-carbon downfield by 13.0 ppm, while the β-carbon is displaced upfield by 4.5 ppm, without any dependence on the size or conformational structure of the rings. Replacement of the transannular 00 group by CH2CH2 or CH2O increases the shielding of the quaternary carbon adjoining it. © 1987 Plenum Publishing Corporation

Conformational properties of 4,4,7,7-tetramethyl-2-hetero-1,3-dioxepanes

4,4,7,7-tetramethyl-1,3-dioxepane and 2,2,4,4,7,7-hexamethyl-2-sila-1,3-dioxepane exist in solution in the twist-boat conformation. © 1987 Plenum Publishing Corporation

Synthesis and stereochemistry of 1H,5H-naphtho[1,8-ef][1,3]dithiocine 2-oxides

3-Substituted 1H,5H-naphtho[1,8-ef][1,3]dithiocines (R = H, Me, Ph, t-Bu) were oxidized with m-chloroperoxybenzoic acid to the corresponding 2-oxides having trans configuration (R ≠ H). According to the 1H and 13C NMR data (including NOESY experiments), the disubstituted compounds at room temperature exist in a boat conformation with equatorial orientation of the substituent on C3 and oxygen atom on S 2. The compound with no substituent on C3 gives rise to a mixture of boat conformers with axial and equatorial sulfoxide oxygen atoms at a ratio of 83:17. © 2005 Pleiades Publishing, Inc

Evidence for a binary origin of a central compact object

© 2016 The Authors.Central compact objects (CCOs) are thought to be young thermally emitting isolated neutron stars that were born during the preceding core-collapse supernova explosion. Here, we present evidence that at least in one case the CCO could have been formed within a binary system. We show that the highly reddened optical source IRAS 17287-3443, located 25 arcsec away from the CCO candidate XMMUJ173203.3-344518 and classified previously as a post asymptotic giant branch star, is indeed surrounded by a dust shell. This shell is heated by the central star to temperatures of ~90 K and observed as extended infrared emission in 8-160 μm band. The dust temperature also increases in the vicinity of the CCO which implies that it likely resides within the shell. We estimate the total dust mass to be ~0.4-1.5 M⊙ which significantly exceeds expected dust yields by normal stars and thus likely condensed from supernova ejecta. Taking into account that both the age of the supernova remnant and the duration of active mass-loss phase by the optical star are much shorter than the total lifetime of either object, the supernova and the onset of the active mass-loss phase of the companion have likely occurred approximately simultaneously. This is most easily explained if the evolution of both objects is interconnected. We conclude, therefore, that both stars were likely members of the same binary system disrupted by a supernova

Suppression of impurity ions optical transitions dephasing in nanocrystals

Abnormally narrow spectral lines have been observed in the luminescence spectra of Y₂SiO₅Pr³⁺ and YVO₄:Eu³⁺ nanocrystals at the room temperature. This fact was interpreted as the result of optical transitions dephasing processes suppression in the nanocrystals. The general cause of the observed effect is the weakening of phonon scattering on the impurity centre as a result of the quantum size effect in nanocrystal phonon subsystem. At first the dependence of spectral line width on the nanocrystal size has been shown. Unnecessary of the deep cooling for narrow optical resonances obtaining makes these nanocrystals a potential candidate for the wide set of applications in the optical memory and quantum computing devices.На спектрах люмінесценції нанокристалів Y₂SiO₅Pr³⁺ та YVO₄:Eu³⁺ за кімнатної температури спостерігалася наявність аномально вузьких спектральних ліній. Це було інтерпретовано як результат заглушення процесів дефазування оптичних переходів у нанокристалах. Причиною зазначеного ефекту є ослаблення розсіювання фононів на домішковому центрі внаслідок впливу квантово-розмірного ефекту на підсистему фононів у нанокристалі. Уперше отримано залежність ширини спектральних ліній від розміру нанокристала. Відсутність потреби глибокого заморожування для отримання вузьких оптичних резонансів відкриває можливості використання таких нанокристалів для створення пристроїв оптичної памяті та квантових компютерів.На спектрах люминесценции нанокристаллов Y₂SiO₅Pr³⁺ и YVO₄:Eu³⁺ при комнатной температуре наблюдалось наличие аномально узких спектральных линий. Это было интерпретировано как результат подавления процессов дефазировки оптических переходов в нанокристаллах. Причиной наблюдаемого эффекта является ослабление рассеяния фононов на примесном центре в результате влияния квантово-размерного эффекта на подсистему фононов в нанокристалле. Впервые получена зависимость ширины спектральных линий от размера нанокристалла. Отсутствие необходимости глубокого замораживания для получения узких оптических резонансов открывает широкие возможности применения данных нанокристаллов для создания устройств оптической памяти и квантовых компьютеров

A 0535+26 in the August/September 2005 outburst observed by RXTE and INTEGRAL

In this Letter we present results from INTEGRAL and RXTE observations of the spectral and timing behavior of the High Mass X-ray Binary A 0535+26 during its August/September 2005 normal (type I) outburst with an average flux F(5-100keV)~400mCrab. The search for cyclotron resonance scattering features (fundamental and harmonic) is one major focus of the paper. Our analysis is based on data from INTEGRAL and RXTE Target of Opportunity Observations performed during the outburst. The pulse period is determined. X-ray pulse profiles in different energy ranges are analyzed. The broad band INTEGRAL and RXTE pulse phase averaged X-ray spectra are studied. The evolution of the fundamental cyclotron line at different luminosities is analyzed. The pulse period P is measured to be 103.39315(5)s at MJD 53614.5137. Two absorption features are detected in the phase averaged spectra at E_1~45keV and E_2~100keV. These can be interpreted as the fundamental cyclotron resonance scattering feature and its first harmonic and therefore the magnetic field can be estimated to be B~4x10^12G.Comment: 4 pages, 5 figures, accepted for publication in A&A Letter