СИНТЕЗ И ХАРАКТЕРИЗАЦИЯ ТРИМЕТИЛ(ФЕНИЛ)СИЛАНА — ПРЕДШЕСТВЕННИКА ДЛЯ ГАЗОФАЗНЫХ ПРОЦЕССОВ ОСАЖДЕНИЯ ПЛЕНОК SiCx : H

The technique of synthesis and purification of trimethyl(phenyl)silane PhSiMe3, allowing to obtain the product with high yield. Individuality of the product was confirmed by elemental analysis for C, H, Si. IR, UV and 1H NMR–spectroscopic studies, defined its spectral characteristics. Complex thermal analysis and thermogravimetric defined thermoanalytical behavior effects of PhSiMe3 in an inert atmosphere. Tensimetric studies have shown that the compound has sufficient volatility and thermal stability for use as a precursor in the process of chemical vapor deposition (CVD). The composition and temperature limits of the possible crystalline phase complexes in equilibrium with the gas phase of different composition has been determed by method of thermodynamic modeling. Calculated CVD diagrams allow us to select the optimum conditions of film deposition. The possibility of using trimethyl(phenyl)silane in CVD processes for producing dielectric films of hydrogenated silicon carbide has been demonstrated. Разработана методика синтеза и очистки триметил(фенил)силана PhSiMe3, позволяющая получать целевой продукт с высоким выходом. Индивидуальность соединения подтверждена элементным анализом на C, H, Si. ИК−, УФ− и ЯМР−спектроскопическими исследованиями (1Н, 13C, 29Si) определены его спектральные характеристики. С помощью комплексного термического анализа определены термоаналитические и термогравиметрические эффекты поведения PhSiMe3 в инертной атмосфере. На основе данных тензометрических исследований показано, что это соединение обладает достаточной летучестью и термической устойчивостью для использования в качестве прекурсора в процессах химического осаждения из газовой фазы (CVD). Методом термодинамического моделирования определен состав и температурные границы возможных кристаллических фазовых комплексов в равновесии с газовой фазой различного состава. Рассчитанные CVD− диаграммы позволяют выбрать оптимальные условия процессов осаждения из газовой фазы пленок. Показана возможность использования PhSiMe3 в процессах CVD для получения диэлектрических пленок гидрогенизированного карбида кремния.

Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications

BACKGROUND Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients. OBJECTIVES To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs. DESIGN This was a prospective international 1-week observational study using the ‘Assess Respiratory Risk in Surgical Patients in Catalonia risk score’ (ARISCAT score) for PPC for risk stratification. PATIENTS AND SETTING Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries. MAIN OUTCOME MEASURES The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes. RESULTS A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (VT) size was 500 ml, or 7 to 9 ml kg1 predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P < 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P < 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure. CONCLUSION The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high VT and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome

Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications: LAS VEGAS - An observational study in 29 countries

BACKGROUND Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients. OBJECTIVES To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs. DESIGN This was a prospective international 1-week observational study using the ‘Assess Respiratory Risk in Surgical Patients in Catalonia risk score’ (ARISCAT score) for PPC for risk stratification. PATIENTS AND SETTING Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries. MAIN OUTCOME MEASURES The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes. RESULTS A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (V T) size was 500 ml, or 7 to 9 ml kg−1 predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P ˂ 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P ˂ 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure. CONCLUSION The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high V T and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome.</p

What drugs do hypertension patients take in clinical practice? Structure of antihypertensive drugs in a large siberian region

Objective. To assess the frequency of prescribing of different groups of antihypertensive drugs (AHD) in the treatment of patients with arterial hypertension (AH) among patients of the Krasnoyarsk territory according to the Russian epidemiological studies ESSE-RF.Materials and methods. 1,603 persons aged 25–64 years, selected through systematic stratified multistage randomization among the population attached to the four outpatient clinics of Krasnoyarsk and Berezovsky district hospital were studied. All included subjects were subjected to a detailed survey of office blood pressure measurements. Results. The proportion of those on monotherapy was 53.4%. The most commonly accepted AHD, including in the combination therapy, were angiotensin-converting enzyme inhibitors (ACEI) – in 51% of cases, beta-blockers – 28.9 percent, angiotensin receptor blockers (ARBS) – 25,2%, diuretics – 23,2%, calcium channel blockers (CCB) – 11.9%, central action drugs – 2.0% and alpha-blockers – 0.4 percent. Beta-blockers often were taken by those of younger age – 38.1 per cent, mainly men aged 25–34 years (50.0 per cent). Among the combinations of AHD the most frequently encountered combination was ACEI + diuretic (6,8%), followed by rthe frequency of prescription by ARBS + diuretic, beta-blocker + diuretics, ARBS + CCB, ACE-I + CCB.Conclusion. The frequent prescription of ACE inhibitors and insignificant use of central action is noted. The high level of violence of use of AHD monotherapy in patients with hypertension (53,4%) is alarming, which may be one of the reason for the relatively low efficiency of antihypertensive therapy (31.6 percent). Beta-blockers were indicated unreasonably often for young men with hypertension aged 25–34 years

Synthesis, Properties and Aging of ICP-CVD SiCxNy:H Films Formed from Tetramethyldisilazane

Amorphous hydrogenated silicon carbonitride films were synthesized on Si(100), Ge(111), and fused silica substrates using the inductively coupled plasma chemical vapor deposition technique. 1,1,3,3-tetramethyldisilazane (TMDSN) was used as a single-source precursor. The effect of the precursor&rsquo;s pressure in the initial gas mixture, the substrate temperature, the plasma power, and the flow rate of nitrogen gas as an additional reagent on the film growth rate, element composition, chemical bonding, wettability of film surface, and the optical and mechanical properties of a-SiCxNy:H films was investigated. In situ diagnostic studies of the gas phase have been performed by optical emission spectroscopy during the film deposition process. The long-term stability of films was studied over a period of 375 days. Fourier-transform infrared (FTIR) and X-ray energy dispersive spectroscopy (EDX), and wettability measurements elucidated the oxidation of the SiCxNy:H films deposited using TMDSN + N2 mixture. Films obtained from a mixture with argon had high stability and maintained the stability of element composition after long-term storage in ambient air

Trimethyl(phenyl)silane — a precursor for gas phase processes of SiCx:H film deposition: Synthesis and characterization

The technique of synthesis and purification of trimethyl(phenyl)silane PhSiMe3, allowing to obtain the product with high yield. Individuality of the product was confirmed by elemental analysis for C, H, Si was developed. IR, UV and 1H NMR-spectroscopic studies were used to define its spectral characteristics. Complex thermal analysis and thermogravimetry defined thermoanalytical behavior of PhSiMe3 in an inert atmosphere. Tensimetric studies have shown that the compound has sufficient volatility and thermal stability for use as a precursor in the process of chemical vapor deposition (CVD). The composition and temperature limits of the possible crystalline phase complexes in equilibrium with the gas phase of different composition has been determined by method of thermodynamic modeling. Calculated CVD diagrams allow us to select the optimal conditions of film deposition. The possibility of using trimethyl(phenyl)silane in CVD processes for producing dielectric films of hydrogenated silicon carbide has been demonstrated

Chemical character of BCxNy layers grown by CVD with trimethylamine borane

Layers of BCxNy were produced in a chemical vapour deposition (CVD) process using trimethylamine borane with He, N2, and NH3, respectively, as precursor. These layers deposited on Si (100) wafers were characterized chemically by X-ray photoelectron spectroscopy (XPS) and synchrotron radiation-based total reflection X-ray fluorescence analysis combined with near-edge X-ray absorption fine structure spectroscopy (TXRF-NEXAFS). As a result, the composition of the material produced without NH3 is a B-C bonds containing compound with an atomic relation 1:1. Adding NH3 with a partial pressure of up to about 1.3 Pa the product could be identified as B2C2N. Increasing the partial pressure of NH3 to 1.7 and 2.1 Pa the product was enriched in nitrogen yielding a compound characterized as h-BCN. In all cases an impurity of oxygen was observed

Chemical bonding in carbonitride nanolayers

First results are presented for the identification of chemical bonds and structures (speciation) in boron and silicon carbonitrides, produced as layers of some hundred nm. The boron carbonitride (BCxNy) films are synthesized by low-pressure chemical vapor deposition (LPCVD) using the precursor substance trimethylamine borane. The samples of silicon carbonitride (SiCxNy) films are synthesized by plasma-enhanced chemical vapor deposition (PECVD) using hexamethyl disilazane. The measurements were performed by total reflection X-ray fluorescence analysis combined with near-edge X-ray absorption fine structure investigations (TXRF-NEXAFS) and by X-ray photo-electron spectroscopy (XPS). The results are compared with those obtained for standard samples boron carbide (B4C), boron nitride (e.g., h-BN, c-BN), silicon carbide (SiC), and silicon nitride (Si3N4)