2,399 research outputs found
Finite element model for vibration and buckling of functionally graded sandwich beams based on a refined shear deformation theory
Finite element model for vibration and buckling of functionally graded sandwich beams based on a refined shear deformation theory is presented. The core of sandwich beam is fully metal or ceramic and skins are composed of a functionally graded material across the depth. Governing equations of motion and boundary conditions are derived from the Hamiltonβs principle. Effects of power-law index, span-to-height ratio, core thickness and boundary conditions on the natural frequencies, critical buckling loads and loadβfrequency curves of sandwich beams are discussed. Numerical results show that the above-mentioned effects play very important role on the vibration and buckling analysis of functionally graded sandwich beams
Random perturbations of the transverse motion of protons in a linear accelerator and their correction
INTERSTITIAL BORON-INTERSTITIAL OXYGEN COMPLEX IN SILICON: LOCAL VIBRATIONAL MODE ARACTERIZATION
Concomitant homozygosity for the prothrombin gene variant with mild deficiency of antithrombin III in a patient with multiple hepatic infarctions: a case report
<p>Abstract</p> <p>Introduction</p> <p>Hereditary causes of visceral thrombosis or thrombosis should be sought among young patients. We present a case of a young man presenting with multiple hepatic infarctions resulting in portal hypertension due to homozygosity of the prothrombin gene mutation not previously described in literature.</p> <p>Case presentation</p> <p>A 42-year-old Caucasian man with a previous history of idiopathic deep vein thrombosis 11 years earlier presented with vague abdominal pains and mildly abnormal liver function tests. An ultrasound and computed tomography scan showed evidence of hepatic infarction and portal hypertension (splenic varices). A thrombophilia screen confirmed a homozygous mutation for the prothrombin gene mutation, with mildly reduced levels of anti-thrombin III (AT III). Subsequent testing of his father and brother revealed heterozygosity for the same gene mutation.</p> <p>Conclusion</p> <p>Hepatic infarction is unusual due to the rich dual arterial and venous blood supply to the liver. In the absence of an arterial or haemodynamic insult causing hepatic infarction, a thrombophilia should be considered. To our knowledge, this is the first reported case of a hepatic infarction due to homozygosity of the prothrombin gene mutation. It is unclear whether homozygotes have a higher risk of thrombosis than heterozygotes. In someone presenting with a first thrombosis with this mutation, the case for life-long anticoagulation is unclear, but it may be necessary to prevent a second and more severe second thrombotic event, as occurred in this case.</p
ΠΠ°Π»ΠΈΠ±ΡΠΎΠ²ΠΎΡΠ½ΡΠ΅ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΡ Π΄Π»Ρ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΠΈ Π²Π°ΠΊΠ°Π½ΡΠΈΠΎΠ½Π½ΠΎ-ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄Π½ΡΡ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠΎΠ² ΠΈ ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄Π½ΠΎΠ³ΠΎ Π΄ΠΈΠΌΠ΅ΡΠ° Π² ΠΊΡΠ΅ΠΌΠ½ΠΈΠΈ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΠΠ-ΠΏΠΎΠ³Π»ΠΎΡΠ΅Π½ΠΈΡ
Vacancy-oxygen complexes VnOm (n, m β₯ 1) in crystalline silicon are nucleation centers for oxygen precipitates, which are widely used as internal getters in modern technologies of production of silicon-based electronic devices and integrated circuits. For the controllable formation of oxygen precipitates in Si crystals in the technology processes the methods of determination of concentrations of the VnOm complexes are required. The aim of the present work was to find values of the calibration coefficients for determination of concentrations of the VnOm defects in Si from intensities of infrared (IR) absorption bands associated with the local vibrational modes (LVM) of these complexes. A combined electrical (Hall effect) and optical (IR absorption) study of vacancy-oxygen defects in identical silicon crystals irradiated with 6 MeV electrons was carried out. Based on the analysis of the data obtained, the values of the calibration coefficient for the determination of concentration of the vacancy-oxygen (VO) complex in silicon by the infrared absorption method were established: for measurements at room temperature (RT) β NVO = 8.5 Β· 1016 Β· Ξ±VO-RT cmβ3, in the case of low-temperature (LT, Π’ β‘ 10 K) measurements β NVO = 3.5 Β· 1016 Β· Ξ±VO-LT cmβ3, where Ξ±VO-RT(LT) are absorption coefficients in maxima of the LVM bands due to the VO complex in the spectra measured at corresponding temperatures. Calibration coefficients for the determination of concentrations of other VnOm (VO2, VO3, VO4, V2O and V3O) complexes and the oxygen dimer (O2) from an analysis of infrared absorption spectra measured at room temperature have been also determined.ΠΠ°ΠΊΠ°Π½ΡΠΈΠΎΠ½Π½ΠΎ-ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄Π½ΡΠ΅ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΡ VnOm (n, m β₯ 1) Π² ΠΊΡΠΈΡΡΠ°Π»Π»Π°Ρ
ΠΊΡΠ΅ΠΌΠ½ΠΈΡ ΡΠ²Π»ΡΡΡΡΡ ΡΠ΅Π½ΡΡΠ°ΠΌΠΈ Π·Π°ΡΠΎΠΆΠ΄Π΅Π½ΠΈΡ ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄Π½ΡΡ
ΠΏΡΠ΅ΡΠΈΠΏΠΈΡΠ°ΡΠΎΠ², ΠΊΠΎΡΠΎΡΡΠ΅ ΡΠΈΡΠΎΠΊΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΡΡΡΡ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ Π²Π½ΡΡΡΠ΅Π½Π½ΠΈΡ
Π³Π΅ΡΡΠ΅ΡΠΎΠ² Π½Π΅ΠΆΠ΅Π»Π°ΡΠ΅Π»ΡΠ½ΡΡ
ΠΏΡΠΈΠΌΠ΅ΡΠ΅ΠΉ Π² ΡΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΡΡ
ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΡΡ
ΠΈΠ·Π³ΠΎΡΠΎΠ²Π»Π΅Π½ΠΈΡ ΠΊΡΠ΅ΠΌΠ½ΠΈΠ΅Π²ΡΡ
ΡΠ»Π΅ΠΊΡΡΠΎΠ½Π½ΡΡ
ΠΏΡΠΈΠ±ΠΎΡΠΎΠ² ΠΈ ΠΈΠ½ΡΠ΅Π³ΡΠ°Π»ΡΠ½ΡΡ
ΠΌΠΈ ΠΊΡΠΎΡΡ
Π΅ΠΌ. ΠΠ»Ρ ΠΊΠΎΠ½ΡΡΠΎΠ»ΠΈΡΡΠ΅ΠΌΠΎΠ³ΠΎ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄Π½ΡΡ
ΠΏΡΠ΅ΡΠΈΠΏΠΈΡΠ°ΡΠΎΠ² Π² ΠΊΡΠΈΡΡΠ°Π»Π»Π°Ρ
Si Π² ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΏΡΠΎΡΠ΅ΡΡΠ°Ρ
Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΡ ΠΌΠ΅ΡΠΎΠ΄Ρ ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΡ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΠΈ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠΎΠ² VnOm. Π¦Π΅Π»ΡΡ Π½Π°ΡΡΠΎΡΡΠ΅ΠΉ ΡΠ°Π±ΠΎΡΡ Π±ΡΠ»ΠΎ Π½Π°Ρ
ΠΎΠΆΠ΄Π΅Π½ΠΈΠ΅ ΠΊΠ°Π»ΠΈΠ±ΡΠΎΠ²ΠΎΡΠ½ΡΡ
ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠΎΠ² Π΄Π»Ρ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΠΈ Π²Π°ΠΊΠ°Π½ΡΠΈΠΎΠ½Π½ΠΎ-ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄Π½ΡΡ
Π΄Π΅ΡΠ΅ΠΊΡΠΎΠ² Π² ΠΊΡΠ΅ΠΌΠ½ΠΈΠΈ ΠΈΠ· ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΠ΅ΠΉ ΠΏΠΎΠ»ΠΎΡ ΠΈΠ½ΡΡΠ°ΠΊΡΠ°ΡΠ½ΠΎΠ³ΠΎ (ΠΠ) ΠΏΠΎΠ³Π»ΠΎΡΠ΅Π½ΠΈΡ, ΡΠ²ΡΠ·Π°Π½Π½ΡΡ
Ρ Π»ΠΎΠΊΠ°Π»ΡΠ½ΡΠΌΠΈ ΠΊΠΎΠ»Π΅Π±Π°ΡΠ΅Π»ΡΠ½ΡΠΌΠΈ ΠΌΠΎΠ΄Π°ΠΌΠΈ (ΠΠΠ) ΡΡΠΈΡ
ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠΎΠ². Π‘ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
(ΡΡΡΠ΅ΠΊΡ Π₯ΠΎΠ»Π»Π°) ΠΈ ΠΎΠΏΡΠΈΡΠ΅ΡΠΊΠΈΡ
(ΠΠ ΠΏΠΎΠ³Π»ΠΎΡΠ΅Π½ΠΈΠ΅) ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΠΉ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΎ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ½ΠΎΠ΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ Π²Π°ΠΊΠ°Π½ΡΠΈΠΎΠ½Π½ΠΎ-ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄Π½ΡΡ
ΡΠ΅Π½ΡΡΠΎΠ² Π² ΠΊΡΠΈΡΡΠ°Π»Π»Π°Ρ
ΠΊΡΠ΅ΠΌΠ½ΠΈΡ, ΠΎΠ±Π»ΡΡΠ΅Π½Π½ΡΡ
ΡΠ»Π΅ΠΊΡΡΠΎΠ½Π°ΠΌΠΈ Ρ ΡΠ½Π΅ΡΠ³ΠΈΠ΅ΠΉ 6 ΠΡΠ. ΠΠ° ΠΎΡΠ½ΠΎΠ²Π΅ Π°Π½Π°Π»ΠΈΠ·Π° ΠΏΠΎΠ»ΡΡΠ΅Π½Π½ΡΡ
Π΄Π°Π½Π½ΡΡ
ΡΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Ρ Π·Π½Π°ΡΠ΅Π½ΠΈΡ ΠΊΠ°Π»ΠΈΠ±ΡΠΎΠ²ΠΎΡΠ½ΡΡ
ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠΎΠ² Π΄Π»Ρ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΠΈ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ° Π²Π°ΠΊΠ°Π½ΡΠΈΡ-ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄ (VO) Π² ΠΊΡΠ΅ΠΌΠ½ΠΈΠΈ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ ΠΈΠ½ΡΡΠ°ΠΊΡΠ°ΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΠ³Π»ΠΎΡΠ΅Π½ΠΈΡ: Π΄Π»Ρ ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΠΉ ΠΏΡΠΈ ΠΊΠΎΠΌΠ½Π°ΡΠ½ΠΎΠΉ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ΅ (RT) β NVO = 8,5 Β· 1016 Β· Ξ±VO-RT ΡΠΌβ3, Π² ΡΠ»ΡΡΠ°Π΅ Π½ΠΈΠ·ΠΊΠΎΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ½ΡΡ
(LT, Π’ β‘ 10 Π) ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΠΉ β N VO = 3,5 Β· 1016 Β· Ξ±VO-LT ΡΠΌβ3, Π³Π΄Π΅ Ξ±VO-RT(LT) β ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΡ ΠΏΠΎΠ³Π»ΠΎΡΠ΅Π½ΠΈΡ Π² ΠΌΠ°ΠΊΡΠΈΠΌΡΠΌΠ°Ρ
ΠΏΠΎΠ»ΠΎΡ ΠΠΠ ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠ° VO Π² ΡΠΏΠ΅ΠΊΡΡΠ°Ρ
, ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½Π½ΡΡ
ΠΏΡΠΈ ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²ΡΡΡΠ΅ΠΉ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ΅. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Ρ ΡΠ°ΠΊΠΆΠ΅ ΠΊΠ°Π»ΠΈΠ±ΡΠΎΠ²ΠΎΡΠ½ΡΠ΅ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΡ Π΄Π»Ρ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΠΉ Π΄ΡΡΠ³ΠΈΡ
Π²Π°ΠΊΠ°Π½ΡΠΈΠΎΠ½Π½ΠΎ-ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄Π½ΡΡ
ΠΊΠΎΠΌΠΏΠ»Π΅ΠΊΡΠΎΠ² VnOm (VO2, VO3, VO4, V2O ΠΈ V3O) ΠΈ ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄Π½ΠΎΠ³ΠΎ Π΄ΠΈΠΌΠ΅ΡΠ° (O2) ΠΈΠ· Π°Π½Π°Π»ΠΈΠ·Π° ΡΠΏΠ΅ΠΊΡΡΠΎΠ² ΠΏΠΎΠ³Π»ΠΎΡΠ΅Π½ΠΈΡ ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½Π½ΡΡ
ΠΏΡΠΈ ΠΊΠΎΠΌΠ½Π°ΡΠ½ΠΎΠΉ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ΅
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