Impurity-induced step interactions: a kinetic Monte-Carlo study

A one-dimensional continuum description of growth on vicinal surfaces in the presence of immobile impurities predicts that the impurities can induce step bunching when they suppress the diffusion of adatoms on the surface. In the present communication we verify this prediction by kinetic Monte-Carlo simulations of a two-dimensional solid-on-solid model. We identify the conditions where quasi one-dimensional step flow is stable against island formation or step meandering, and analyse in detail the statistics of the impurity concentration profile. The sign and strength of the impurity-induced step interactions is determined by monitoring the motion of pairs of steps. Assemblies containing up to 20 steps turn out to be unstable towards the emission of single steps. This behavior is traced back to the small value of the effective, impurity-induced attachment asymmetry for adatoms. An analytic estimate for the critical number of steps needed to stabilize a bunch is derived and confirmed by simulations of a one-dimensional model.Comment: 9 pages, 8 figure

Optimization of preparation condition of Ce1-xMxOy AND Ni/Ce1-xMxOy (M = Gd, La, Mg) nanomaterials for hydrogen power engineering

Nanomaterials Ce1-xMxOy and Ni/Ce1-xMxOy (M = Gd, La, Mg, x = 0-0,5) were prepared at variation of temperature, medium and duration of thermal treatment. The effects of type (M = Gd, La, Mg) and content (x = 0-0,5) of doping cation (M) on crystal structure and sintering of nanomaterials during calcination were investigated. It was shown that phase composition of materials did not change under rising of calcination temperature up to 800oC. The material stability against the sintering during thermal treatment increases at an increase of La or Mg content in the materials. The comparative study of functional properties of Ni/Ce1-xMxOy materials was carried out in autothermal reforming of ethanol (ATR of C2H5OH). It is demonstrated that Ni/Ce1-xMxOy samples provide high hydrogen yield in ATR of C2H5OH, which indicates their perspective application for hydrogen power engineering

Pulse contour analysis after normothermic cardiopulmonary bypass in cardiac surgery patients

INTRODUCTION: Monitoring of the cardiac output by continuous arterial pulse contour (CO(PiCCOpulse)) analysis is a clinically validated procedure proved to be an alternative to the pulmonary artery catheter thermodilution cardiac output (CO(PACtherm)) in cardiac surgical patients. There is ongoing debate, however, of whether the CO(PiCCOpulse )is accurate after profound hemodynamic changes. The aim of this study was therefore to compare the CO(PiCCOpulse )after cardiopulmonary bypass (CPB) with a simultaneous measurement of the CO(PACtherm). METHODS: After ethical approval and written informed consent, data of 45 patients were analyzed during this prospective study. During coronary artery bypass graft surgery, the aortic transpulmonary thermodilution cardiac output (CO(PiCCOtherm)) and the CO(PACtherm )were determined in all patients. Prior to surgery, the CO(PiCCOpulse )was calibrated by triple transpulmonary thermodilution measurement of the CO(PiCCOtherm). After termination of CPB, the CO(PiCCOpulse )was documented. Both CO(PACtherm )and CO(PiCCOtherm )were also simultaneously determined and documented. RESULTS: Regression analysis between CO(PACtherm )and CO(PiCCOtherm )prior to CPB showed a correlation coefficient of 0.95 (P < 0.001), and after CPB showed a correlation coefficient of 0.82 (P < 0.001). Bland-Altman analysis showed a mean bias and limits of agreement of 0.0 l/minute and -1.4 to +1.4 l/minute prior to CPB and of 0.3 l/minute and -1.9 to +2.5 l/minute after CPB, respectively. Regression analysis of CO(PiCCOpulse )versus CO(PiCCOtherm )and of CO(PiCCOpulse )versus CO(PACtherm )after CPB showed a correlation coefficient of 0.67 (P < 0.001) and 0.63 (P < 0.001), respectively. Bland-Altman analysis showed a mean bias and limits of agreement of -1.1 l/minute and -1.9 to +4.1 l/minute versus -1.4 l/minute and -4.8 to +2.0 l/minute, respectively. CONCLUSION: We observed an excellent correlation of CO(PiCCOtherm )and CO(PACtherm )measurement prior to CPB. Pulse contour analysis did not yield reliable results with acceptable accuracy and limits of agreement under difficult conditions after weaning from CPB in cardiac surgical patients. The pulse contour analysis thus should be re-calibrated as soon as possible, to prevent false therapeutic consequences

Spacings of Quarkonium Levels with the Same Principal Quantum Number

The spacings between bound-state levels of the Schr\"odinger equation with the same principal quantum number $N$ but orbital angular momenta $\ell$ differing by unity are found to be nearly equal for a wide range of power potentials $V = \lambda r^\nu$, with $E_{N \ell} \approx F(\nu, N) - G(\nu,N) \ell$. Semiclassical approximations are in accord with this behavior. The result is applied to estimates of masses for quarkonium levels which have not yet been observed, including the 2P $c \bar c$ states and the 1D $b \bar b$ states.Comment: 20 pages, latex, 3 uuencoded figures submitted separately (process using psfig.sty

Особенности и эффективность проведения геолого-технических мероприятий на Шингинском нефтяном месторождении (Томская область)

Целью данной работы является анализ эффективности проведенных геолого-технических мероприятий на Шингинском нефтяном месторождении. В процессе работы были выявлены наиболее эффективные, и наиболее часто проводимые ГТМ, а также рассчитана экономическая эффективность от проведения гидроразрыва пласта.The purpose of this work is to analyze the effectiveness of geological and technical measures carried out at the Shinginskoye field. In the course of the work, the most effective and most frequently performed geological and technical measures were determined and the economic efficiency of the hydraulic fracture was calculated

The impact of an hematocrit of 20% during normothermic cardiopulmonary bypass for elective low risk coronary artery bypass graft surgery on oxygen delivery and clinical outcome – a randomized controlled study [ISRCTN35655335]

INTRODUCTION: Cardiopulmonary bypass (CPB) induces hemodilutional anemia, which frequently requires the transfusion of blood products. The objective of this study was to evaluate oxygen delivery and consumption and clinical outcome in low risk patients who were allocated to an hematocrit (Hct) of 20% versus 25% during normothermic CPB for elective coronary artery bypass graft (CABG) surgery. METHODS: This study was a prospective, randomized and controlled trial. Patients were subjected to normothermic CPB (35 to 36°C) and were observed until discharge from the intensive care unit (ICU). Outcome measures were calculated whole body oxygen delivery, oxygen consumption and clinical outcome. A nonparametric multivariate analysis of variance for repeated measurements and small sample sizes was performed. RESULTS: In a total of 54 patients (25% Hct, n = 28; 20% Hct, n = 26), calculated oxygen delivery (p = 0.11), oxygen consumption (p = 0.06) and blood lactate (p = 0.60) were not significantly different between groups. Clinical outcomes were not different between groups. CONCLUSION: These data indicate that an Hct of 20% during normothermic CPB maintained calculated whole body oxygen delivery above a critical level after elective CABG surgery in low risk patients. The question of whether a transfusion trigger in excess of 20% Hct during normothermic CPB is still supported requires a larger prospective and randomized trial

Технологические решения для строительства разведочной вертикальной скважины глубиной 2900 метров на нефтяном месторождении (Томская область)

Выпускная квалификационная работа посвящена практическому решению задачи бурения разведывательной скважины, оптимизации процесса бурения, подбор необходимого инструмента и выбор промывочной жидкости и последующих режимов бурения, также работа включает в семя и рассматривает такую тему как проблем как вынос песка из пласта и способы предотвращения подобных негативных моментов. Так же в работе содержатся результаты расчетов режима бурения, подробное обоснование выбора инструмента и предложены пути оптимизации действующего проекта.The final qualification work is devoted to the practical solution of the problem of drilling an exploration well, optimizing the drilling process, selecting the necessary tools and choosing the washing liquid and subsequent drilling modes, and the work also includes and considers such a topic as problems such as sand removal from the reservoir and ways to prevent such negative moments. The paper also contains the results of calculations of the drilling mode, a detailed justification for the choice of the tool, and offers ways to optimize the current project. This work contains an introduction, sections, conclusion, and a list of references

Study of heat transfer processes in the flowing part of hypersonic air-ramjet engine

The technique and results of the experimental-theoretical study of gas dynamics, heat transfer and the structure of gas flow in the flowing channel of a model hypersonic air-ramjet engine are presented for Mach numbers M (5; 6)