407 research outputs found
The T1 state of p-nitroaniline and related molecules: a CNDO/S study
No full textThe nature of the lowest energy triplet state (T1) of p-nitroaniline (PNA), N,N-dimethyl-p-nitroaniline (DMPNA) and nitrobenzene (NB) is reexamd. using the semiempirical CNDO/S-CI method with selected parameter options. In the case of the unperturbed mols. the short-axis polarized p* A- singlet excitation. Computations suggest, however, that polar solvents strongly stabilize the PNA and DMPNA p* <- p charge-transfer triplet relative to other excitations, whereas specific solvent hydrogen-bonded interactions stabilize the p* <- n(s) triplet of NB below those of p* <- p character. These assignments allow a rationalization of phosphorescence lifetime data, Tn <- T1 absorption measurements and relative photochem. behavior
Factors Associated with In-Hospital Mortality in Elderly Internal Medicine Patients with Nasogastric Tube Feeding
No full textGalina Plotnikov,1,2 Saleh Sharif,2,3 Gleb Buturlin,2 Inbal Segal,1 Oleg Gorelik,2 Nadya Kagansky2,4 1Geriatric Assessment Unit, Yitzhak Shamir Medical Center, Zerifin, 7033001, Israel; 2Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv, Israel; 3Department of Internal Medicine C, Yitzhak Shamir Medical Center, Zerifin, 7033001, Israel; 4Shmuel Harofe Geriatric Medical Center, Beer Yaakov, IsraelCorrespondence: Galina Plotnikov, Geriatric Assessment Unit, Yitzhak Shamir Medical Center, Zerifin, 7033001, Israel, Tel +972-8-9542271, Fax +972-8-9779597, Email [email protected]: To evaluate demographic, clinical, and laboratory variables, and their associations with in-hospital mortality, among elderly internal medicine patients with nasogastric tube (NGT) feeding.Patients and Methods: Demographic, clinical, and laboratory data were collected retrospectively for 129 patients aged ≥ 80 years who initiated NGT feeding during their hospitalization in internal medicine wards. The data were compared between survivors and non-survivors. Multivariate logistic regressions were performed to identify the variables most significantly associated with in-hospital mortality.Results: The in-hospital mortality rate was 60.5%. Compared to survivors, non-survivors more often presented with pressure sores (P=0.005) and lymphopenia (P< 0.001), were more often treated with invasive mechanical ventilation (P< 0.001), and less often underwent geriatric assessment (P< 0.001). Non-survivors demonstrated higher mean levels of C-reactive protein, and lower mean values of serum cholesterol, triglycerides, total protein, and albumin (P< 0.001 for all comparisons). On multivariate analysis, the following variables were most significantly associated with in-hospital mortality in the entire cohort: the presence of pressure sores (odds ratio [OR], 4.34; 95% confidence interval [CI], 1.68– 11.48; P=0.003) and lymphopenia (OR, 4.09; 95% CI, 1.51– 11.08; P=0.006), and serum cholesterol (OR, 0.98; 95% CI, 0.96– 0.99; P=0.003).Conclusion: Among elderly acutely ill patients who initiated NGT feeding during hospitalization, in-hospital mortality was extremely high. The factors most strongly associated with in-hospital mortality were the presence of pressure sores and lymphopenia, and lower serum cholesterol levels. These findings may provide useful prognostic information for decision-making regarding initiation of NGT feeding in elderly hospitalized patients.Keywords: aging, enteral feeding, hospitalization, prognosi
Endoscopy-assisted dilatational tracheostomy in patients with COVID-19
No full textOBJECTIVE: To summarize an experience of endoscopy-assisted dilatational tracheostomies in patients with COVID-19. MATERIAL AND METHODS: There were 31 endoscopy-assisted dilatational tracheostomies in patients with COVID-19 for the period from April 17 to June 10, 2020 (11 women and 19 men). Mean age of patients was 66.7 years (range 48-87). Tracheostomy was performed using Ciaglia (22) and Griggs (9) techniques. All procedures were carried out at the intensive care unit in elective fashion. RESULTS: Tracheostomy was performed in 19.8% of ICU patients or 36.9% of all patients on mechanical ventilation within 6.5±2.5 days [min 3, max 11]. There were 22 survivors with tracheostomy (70.9%) that is comparable with survival of patients without mechanical ventilation (79.7%) and slightly higher than in patients on ventilation without tracheostomy (65.4%). No complications during the procedure were noted. CONCLUSION: Endoscopy-assisted dilatational tracheostomy is preferred for prolonged mechanical ventilation, including patients with COVID-19. The undeniable advantages of this operation are fewer intraoperative complications due to endoscopic control, and lower risk of tracheal strictures
An approximation to wave scattering by an ice polynya
No full textIWWWFB24L. G. Bennetts, T. D. Williams and V. A. Squir
An Analysis of Fare Collection Costs on Heavy Rail and Bus Systems in the U.S.
No full textIn this research, an effort is made to analyze the costs of fare collection on heavy rail and motorbus systems in the U.S. Since existing ticketing and fare collection (TFC) systems are major elements of transit infrastructure and there are several new alternative TFC technologies available on the market, the need to evaluate the performance of existing TFC systems arises. However, very little research has been done, so far, to assess impacts of TFC technologies on capital and operating expenses in public transit. The two objectives of this research are: (1) to formulate a conceptual evaluation framework and a plan to assess the operating costs of existing TFC systems in transit and (2) to analyze the operating expenses associated with existing TFC systems on heavy rail and motorbus transit in the U.S. with the aid of the evaluation framework and plan.
This research begins with a review of the current state of knowledge in the areas of transit TFC evaluation, the economics of public transit operations, and fare collection practices and technologies. It helps to determine the scope of work related to assessment of TFC operating costs on public transit and provides the basis for the development of a conceptual evaluation framework and an evaluation plan. Next, this research presents a systematic approach to define and describe alternative TFC systems and suggests that the major TFC system determinants are payment media, fare media, TFC equipment, and transit technology (mode). Following this is the development of measures of effectiveness to evaluate alternative TFC systems. These measures assess cost-effectiveness and labor-intensiveness of TFC operations. The development of TFC System Technology Index follows. This Index recognizes the fact that TFC systems may consist of different sets of TFC technologies both traditional and innovative. Finally, this research presents statistical results that support the hypothesis that TFC operating costs are related to transit demand, transit technology (mode) and TFC technologies. These results further suggest that: (1) TFC operating costs per unlinked passenger trip on heavy rail systems are higher than on motorbus systems and (2) TFC operating costs per unlinked passenger trip tend to increase as the use of non-electronic fare media increases. Actions for further research are also recommended.Ph. D
Dynamics of pulmonary injury and extracorporeal methods of hemocorrection in patients with Sars-CoV-2
No full textPurpose. To assess changes in the degree of pulmonary injury in patients with Sars-CoV-2 after extracorporeal hemocorrection methods (ECHCM). Material and methods. 27 patients with Sars-CoV-2 underwent 48 ECHCM procedures - plasma separation, nonselective cytosorption hemoperfusion, dialysis-filtration techniques. After arriving in the hospital all patients underwent MSCT of the chest organs. The examination was conducted according to the standard protocol of MSCT of the chest organs and reconstruction of soft and high-resolution on a Philips Ingenuity CT 64 multi- detector computed tomograph. The following scanning parameters were used for the standard protocol: 64 × 0.625 collimation, 1 mm reconstruction, 0.5 mm increment. The patient was lying on his back with his arms thrown back behind his head during the procedure. A scan area including the chest was planned by the plan scan. Assessment of the scans was carried out in the Diсom-images viewing module of medical hardware- software complex “ArchiMed” (Med-Ray. Russia, 2004). The percentage of lung parenchyma lesions as well as the severity (CT-1–4) were evaluated according to the recommendations “Radiation diagnosis of coronavirus disease (COVID-19): organization, methodology, interpretation of the results”. CT examinations were compared not earlier than 4 days before ECHCM and not later than 5 days after. Result. With isolated plasmaseparation, the “ground glass” zones passed into the consolidation zones, the total volume of the lesion decreased and the pneumatization increased. In isolated hemoperfusion the dynamics is multidirectional: there are more consolidation zones, less ground glass zones in general, the process is stabilized and the zones of lung tissue damage are reduced. With isolated hemodiafiltration, the consolidation zones decreased, the pneumatization of the lung tissue increased, and subsequently the volume of the lesion and the consolidation zones increased significantly. By combined procedures there are multidirectional dynamics. Conclusion. The effect of ECMGC use on the degree and volume of lung tissue damage in patients with Sars- CoV-2 was not revealed
Efficiency enhancement of oil air coolers in GTN-16 gas-compressor units
No full textНеволин Александр Михайлович, старший преподаватель кафедры «Турбины и двигатели», Уральский федеральный университет им. первого Президента России Б.Н. Ельцина, г. Екатеринбург; [email protected].
Плотников Петр Николаевич, д-р техн. наук, профессор кафедры «Турбины и двигатели», Уральский федеральный университет им. первого Президента России Б.Н. Ельцина, г. Екатеринбург; plot24@
mail.ru.
A.M. Nevolin, Ural Federal University named after the first President of Russia B.N.Yeltsin,
Yekaterinburg, Russian Federation, [email protected],
P.N. Plotnikov, Ural Federal University named after the first President of Russia B.N.Yeltsin,
Yekaterinburg, Russian Federation, plot24@ mail.ruПредставлены результаты численного и экспериментального исследований аппарата воздушного охлаждения масла газотурбинной установки. Экспериментальное исследование проведено в условиях
эксплуатации на газокомпрессорной станции магистрального газопровода. Численное моделирование проведено методом конечных элементов в программе STAR-CCM+. В качестве объекта исследования выбран теплообменник венгерского производства, охлаждающий масло газоперекачивающих агрегатов
на базе газотурбинной установки ГТН-16. Цель исследования – оценить количество теплоты, переданное в маслоохладителе до и после модернизации его воздушного такта. Модернизация заключалась в установке выравнивающего устройства, равномерно распределяющего поток воздуха перед трубным пучком. Проектирование и оптимизация конструкции направляющего устройства были проведены при помощи верифицированной численной конечно-элементной модели. Приведено описание принципа работы и конструкции аппарата, указаны недостатки конструкции, послужившие причиной для данного исследования. Описаны схема и методика проведения натурных
испытаний. В качестве результатов исследования приведены примеры полей скоростей потока воздуха
на входе в теплообменную секцию до и после модернизации. Показано повышение удельного теплосъема секции маслоохладителя после выравнивания поля скоростей воздуха. The paper deals with the results of numerical and experimental studies of gas-turbine unit oil air cooler.
The experimental study was performed under operating conditions of main pipeline gas-compressor station.
The numerical simulation was carried out by means of finite element method in STAR-CCM+ program.
The Hungarian heat exchanger cooling oil of the gas-compressor unit based on gas-turbine unit GTN-16 was
chosen as the research object. The aim of the study was to evaluate oil cooler heat transfer rate before and after
its air circuit modernization. The modernization was to install a leveling apparatus that distributes the air flow
uniformly in front of the tube bank. Design and optimization of the leveling apparatus geometry were made by
means of the verified finite element model.
The paper describes cooler design and operation principle. The design shortcomings that were the reason
for the study are presented. The measuring scheme and field test methods are described. The author gives the
examples of the air flow velocity field in front of the finning before and after modernization as results of the study. The paper states the enhancement of the oil cooler heat flux after the air flow velocity field leveling
The Influence of Cross-profiling of Inlet and Exhaust Pipes on the Gas Exchange Processes in Piston Engines
No full textAbstractIt is known that more than 80% of global energy is produced by internal combustion engines. Therefore, the improvement of working cycles and modernization of systems and components of the piston and combined internal combustion engines with the aim of improving their technical and economic indicators is one of the urgent tasks in the global energy sector. Research studies in this area were carried out mainly by means of numerical simulations or experimentally under static conditions. Information about gas exchange processes in the unsteady gas dynamic conditions are quite limited and controversial. This work aims at obtaining of the additional clarifying information about the gas dynamics in the air-gas tract of the internal combustion engine and finding ways of improving the processes. The results of experimental studies of gas exchange processes in the intake and exhaust tracts piston engines were presented in the article. Experimental studies were conducted on full-scale models of a single-cylinder engine. The experimental dependencies of change of the instantaneous velocity and pressure of the gas flow in the gas paths from the crank angle were presented in the article. Improvement of gas exchange processes in the intake and exhaust pipes of internal combustion engines due to the transverse profiling of the channels was proposed in the paper
Semiconductors V. 36, I. 08
No full textdc.description[en_US]Semiconductors -- August 2002
Volume 36, Issue 8, pp. 837-951
ATOMIC STRUCTURE AND NONELECTRONIC PROPERTIES OF SEMICONDUCTORS
Measurements of Parameters of the Low-Temperature Molecular-Beam Epitaxy of GaAs
V. V. Preobrazhenskii, M. A. Putyato, and B. R. Semyagin
pp. 837-840 Full Text: PDF (60 kB)
Threshold of Inelastic Strain Formation in Si and GaAs Surface Layers under Multiple Pulsed Laser Irradiation
S. V. Vintsents, A. V. Zoteev, and G. S. Plotnikov
pp. 841-844 Full Text: PDF (58 kB)
Dissociation Energies of a CiCs Complex and the A Center in Silicon
N. I. Boyarkina, S. A. Smagulova, and A. A. Artem'ev
pp. 845-847 Full Text: PDF (46 kB)
ATOMIC STRUCTURE AND NONELECTRONIC PROPERTIES
Initial Stages of Growth of Diamond Island Films on Crystalline Silicon
N. A. Feoktistov, V. V. Afanas'ev, V. G. Golubev, S. A. Grudinkin, S. A. Kukushkin, and V. G. Melekhin
pp. 848-851 Full Text: PDF (141 kB)
ELECTRONIC AND OPTICAL PROPERTIES OF SEMICONDUCTORS
Local Structure of Zinc Impurity Centers in Lead Chalcogenides and Pb1 ��� xSnxTe Solid Solutions
S. A. Nemov and N. P. Seregin
pp. 852-854 Full Text: PDF (100 kB)
Influence of Tellurium Impurity on the Properties of Ga1 ��� XInXAsYSb1 ��� Y (X > 0.22) Solid Solutions
T. I. Voronina, T. S. Lagunova, E. V. Kunitsyna, Ya. A. Parkhomenko, M. A. Sipovskaya, and Yu. P. Yakovlev
pp. 855-862 Full Text: PDF (104 kB)
Optical Properties of Bulk and Epitaxial Unordered GaxIn1 ��� xP Semiconductor Alloys
Ya. I. Vyklyuk, V. G. Deibuk, and S. V. Zolotarev
pp. 863-868 Full Text: PDF (89 kB)
Electrical and Thermoelectric Properties of p-Ag2Te
F. F. Aliev, E. M. Kerimova, and S. A. Aliev
pp. 869-873 Full Text: PDF (74 kB)
Photoconductivity of Coarse-Grained CdTe Polycrystals
S. A. Medvedev, Yu. V. Klevkov, S. A. Kolosov, V. S. Krivobok, and A. F. Plotnikov
pp. 874-877 Full Text: PDF (51 kB)
Time-Resolved Photoluminescence of Polycrystalline GaN Layers on Metal Substrates
A. V. Andrianov, K. Yamada, H. Tampo, H. Asahi, V. Yu. Nekrasov, Z. N. Petrovskaya, O. M. Sreseli, and N. N. Zinov'ev
pp. 878-882 Full Text: PDF (66 kB)
SEMICONDUCTOR STRUCTURES, INTERFACES, AND SURFACES
Low-Threshold Defect Formation and Modification of Ge Surface Layer under Elastic and Elastoplastic Pulsed Laser Effects
S. V. Vintsents, V. B. Zaitsev, A. V. Zoteev, G. S. Plotnikov, A. I. Rodionov, and A. V. Chervyakov
pp. 883-888 Full Text: PDF (79 kB)
Electron Tunneling through a Double Barrier in a Reverse-Biased Metal���Oxide���Silicon Structure
G. G. Kareva, M. I. Vexler, I. V. Grekhov, and A. F. Shulekin
pp. 889-894 Full Text: PDF (89 kB)
LOW-DIMENSIONAL SYSTEMS
Structure of Heterointerfaces and Photoluminescence Properties of GaAs/AlAs Superlattices Grown on (311)A and (311)B Surfaces: Comparative Analysis
G. A. Lyubas, N. N. Ledentsov, D. Litvinov, B. R. Semyagin, I. P. Soshnikov, V. M. Ustinov, V. V. Bolotov, and D. Gerthsen
pp. 895-898 Full Text: PDF (138 kB)
Wavelength of Emission from InGaAsN Quantum Wells as a Function of Composition of the Quaternary Compound
A. E. Zhukov, A. R. Kovsh, E. S. Semenova, V. M. Ustinov, L. Wei, J.-S. Wang, and J. Y. Chi
pp. 899-902 Full Text: PDF (66 kB)
Two-Dimensional p���n Junction under Equilibrium Conditions
A. Sh. Achoyan, A. �. Yesayan, �. M. Kazaryan, and S. G. Petrosyan
pp. 903-907 Full Text: PDF (70 kB)
Calculations of the Charge-Carrier Mobility and the Thermoelectric Figure of Merit for Multiple-Quantum-Well Structures
D. A. Pshenai-Severin and Yu. I. Ravich
pp. 908-915 Full Text: PDF (91 kB)
Nonlinear Response and Nonlinear Coherent Generation in Resonant-Tunneling Diode in a Broad Frequency Range
V. F. Elesin, I. Yu. Kateev, and A. I. Podlivaev
pp. 916-920 Full Text: PDF (61 kB)
Anomalies of the Fractional Quantum Hall Effect in a Wide Ballistic Wire
Z. D. Kvon, E. B. Olshanetsky, A. E. Plotnikov, A. I. Toropov, and J. C. Portal
pp. 921-923 Full Text: PDF (46 kB)
Special Features of Electrical Conductivity in a Parabolic Quantum Well in a Magnetic Field
E. P. Sinyavskii and R. A. Khamidullin
pp. 924-928 Full Text: PDF (59 kB)
Manifestation of A(+) Centers in the Luminescence of Two-Dimensional GaAs/AlGaAs Structures
Yu. L. Ivanov, N. V. Agrinskaya, P. V. Petrov, V. M. Ustinov, and G. �. Tsyrlin
pp. 929-931 Full Text: PDF (43 kB)
One-Dimensional Photonic Crystal Obtained by Vertical Anisotropic Etching of Silicon
V. A. Tolmachev, L. S. Granitsyna, E. N. Vlasova, B. Z. Volchek, A. V. Nashchekin, A. D. Remenyuk, and E. V. Astrova
pp. 932-935 Full Text: PDF (263 kB)
AMORPHOUS, VITREOUS, AND POROUS SEMICONDUCTORS
Gamma-Irradiation-Induced Metastable States of Undoped Amorphous Hydrogenated Silicon
M. S. Ablova, G. S. Kulikov, and S. K. Persheev
pp. 936-940 Full Text: PDF (73 kB)
Fabrication and Properties of Amorphous Hydrogenated Boron Carbide Films
A. S. Anan'ev, O. I. Kon'kov, V. M. Lebedev, A. N. Novokhatski, E. I. Terukov, and I. N. Trapeznikova
pp. 941-943 Full Text: PDF (47 kB)
PHYSICS OF SEMICONDUCTOR DEVICES
Lattice-Matched GaInPAsSb/InAs Structures for Devices of Infrared Optoelectronics
M. Aidaraliev, N. V. Zotova, S. A. Karandashev, B. A. Matveev, M. A. Remennyi, N. M. Stus', G. N. Talalakin, V. V. Shustov, V. V. Kuznetsov, and E. A. Kognovitskaya
pp. 944-949 Full Text: PDF (71 kB)
PERSONALIA
Viktor Il'ich Fistul' (on his 75th birthday)
pp. 950-951 Full Text: PDF (71 kB)dc.description.contributor[en_US]dc.description.contributor[en_US
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