The Effect of Nano-SiO2 on the Structural, Electrical and Magnetic Properties of SiO2-LiFe5O8 Glass–ceramics Prepared by Sol Gel Auto-combustion Processing

The glass–ceramic with the composition x(LiFe5O8)/(100 – x) SiO2 (x = 20, 30, 40, 50, 100 wt. % ) were prepared by sol gel auto-combustion method. The influence of the SiO2 ratio in the glass-ceramics strucure prepared was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Crystalline phases (LiFe5O8, SiO2, Fe2O3) were observed by X-ray powder diffraction in the glasses annealed at 800°C for 2h. The crystallite size was found to increase from 27.29 nm (x = 20%) to 91.48 nm(x = 100 %). The microstructure of the formed powders was SiO2 ratio dependent. Increasing the SiO2 ratio was found to inhibit the grain growth of the formed ferrite. The electrical conductivity of glass-ceramics samples were raised with increasing the concentration of SiO2 ratio as the result of increasing the hopping of electrons between Fe2+ and Fe3+ ions. The magnetic characteristics of the prepared glass ceramics were performed using a vibrating sample magnetometer in function of the magnetic field. The samples heat -treated at 800°C for 2h present a ferrimagnetic behavior. Alongside, the formed crystalline silicate lithium ferrite had good magnetic properties. High saturation magnetization (51.9 emu/g) was attained the formed ferrite sample of x = 100 % ratio annealed at 800°C for 2h

The Effect of Nano-SiO2 on the Structural, Electrical and Magnetic Properties of SiO2-LiFe5O8 Glass–ceramics Prepared by Sol Gel Auto-combustion Processing

The glass–ceramic with the composition x(LiFe5O8)/(100 – x) SiO2 (x = 20, 30, 40, 50, 100 wt. % ) were prepared by sol gel auto-combustion method. The influence of the SiO2 ratio in the glass-ceramics strucure prepared was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Crystalline phases (LiFe5O8, SiO2, Fe2O3) were observed by X-ray powder diffraction in the glasses annealed at 800°C for 2h. The crystallite size was found to increase from 27.29 nm (x = 20%) to 91.48 nm(x = 100 %). The microstructure of the formed powders was SiO2 ratio dependent. Increasing the SiO2 ratio was found to inhibit the grain growth of the formed ferrite. The electrical conductivity of glass-ceramics samples were raised with increasing the concentration of SiO2 ratio as the result of increasing the hopping of electrons between Fe2+ and Fe3+ ions. The magnetic characteristics of the prepared glass ceramics were performed using a vibrating sample magnetometer in function of the magnetic field. The samples heat -treated at 800°C for 2h present a ferrimagnetic behavior. Alongside, the formed crystalline silicate lithium ferrite had good magnetic properties. High saturation magnetization (51.9 emu/g) was attained the formed ferrite sample of x = 100 % ratio annealed at 800°C for 2h

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