1.IntroductionThe chemistry of rare earthoxysulphides is well known [1-5] and theyhave extensive technological applications,but the d-transition metal oxysulphides wasnot known until recently [6-9].Therefore,itis nece...1.IntroductionThe chemistry of rare earthoxysulphides is well known [1-5] and theyhave extensive technological applications,but the d-transition metal oxysulphides wasnot known until recently [6-9].Therefore,itis necessary to study the thermodynamicproperties of these compounds.展开更多
This paper reports that low-temperature heat capacities of N-methylnorephedrine C11H17NO（s） have been measured by a precision automated adiabatic calorimeter over the temperature range from T=78K to T=400K. A solid ...This paper reports that low-temperature heat capacities of N-methylnorephedrine C11H17NO（s） have been measured by a precision automated adiabatic calorimeter over the temperature range from T=78K to T=400K. A solid to liquid phase transition of the compound was found in the heat capacity curve in the temperature range of T=342-364 K. The peak temperature, molar enthalpy and entropy of fusion of the substance were determined. The experimental values of the molar heat capacities in the temperature regions of T=78-342 K and T=364-400 K were fitted to two poly- nomial equations of heat capacities with the reduced temperatures by least squares method. The smoothed molar heat capacities and thermodynamic functions of N-methylnorephedrine C11H17NO（s） relative to the standard refer- ence temperature 298.15 K were calculated based on the fitted polynomials and tabulated with an interval of 5 K. The constant-volume energy of combustion of the compound at T=298.15 K was measured by means of an isoperibol precision oxygen-bomb combustion calorimeter. The standard molar enthalpy of combustion of the sample was calculated. The standard molar enthalpy of formation of the compound was determined from the combustion enthalpy and other auxiliary thermodynamic data through a Hess thermochemical cycle.展开更多
AIM: To assess the value of plasma melatonin in pre-dicting acute pancreatitis when combined with the acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) and bedside index for severity in acute pancreatitis ...AIM: To assess the value of plasma melatonin in pre-dicting acute pancreatitis when combined with the acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) and bedside index for severity in acute pancreatitis (BISAP) scoring systems. METHODS: APACHEⅡ and BISAP scores were calculated for 55 patients with acute physiology (AP) in the first 24 h of admission to the hospital. Additionally, morning (6:00 AM) serum melatonin concentrations were measured on the first day after admission. According to the diagnosis and treatment guidelines for acute pancreatitis in China, 42 patients suffered mild AP (MAP). The other 13 patients developed severe AP (SAP). A total of 45 healthy volunteers were used in this study as controls. The ability of melatonin and the APACHEⅡ and BISAP scoring systems to predict SAP was evaluated using a receiver operating characteristic (ROC) curve. The optimal melatonin cutoff concentration for SAP patients, based on the ROC curve, was used to classify the patients into either a high concen-tration group (34 cases) or a low concentration group (21 cases). Differences in the incidence of high scores, according to the APACHEⅡ and BISAP scoring sys- tems, were compared between the two groups. RESULTS: The MAP patients had increased melatonin levels compared to the SAP (38.34 ng/L vs 26.77 ng/L) (P = 0.021) and control patients (38.34 ng/L vs 30.73 ng/L) (P = 0.003). There was no significant difference inmelatoninconcentrations between the SAP group and the control group. The accuracy of determining SAP based on the melatonin level, the APACHEⅡ score and the BISAP score was 0.758, 0.872, and 0.906, respectively, according to the ROC curve. A melatonin concentration ≤ 28.74 ng/L was associated with an increased risk of developing SAP. The incidence of high scores (≥ 3) using the BISAP system was significantly higher in patients with low melatonin concentration (≤ 28.74 ng/L) compared to patients with high melatonin concentration (> 28.74 ng/L) (42.9% vs 14.7%, P = 0.02). The incidence of high APACHEⅡ scores (≥ 10) between the two groups was not significantly different. CONCLUSION: The melatonin concentration is closely related to the severity of AP and the BISAP score. Therefore, we can evaluate the severity of disease by measuring the levels of serum melatonin.展开更多
The Gibbs standard free energies of formation of the fluorides and the oxyfluorides of Y. Gd. Dy, Tb,Ho. Er and Yb were measured by using either a calcium concentration cell with Caβ' / β+x-Al_2O_3 solidelectrol...The Gibbs standard free energies of formation of the fluorides and the oxyfluorides of Y. Gd. Dy, Tb,Ho. Er and Yb were measured by using either a calcium concentration cell with Caβ' / β+x-Al_2O_3 solidelectrolyte or an oxygen concentration cell with calcia stabilized zirconia (CSZ) solid electrolyte, accordingto which the phase stability diagram of RE-O-F systems were determined.展开更多
文摘1.IntroductionThe chemistry of rare earthoxysulphides is well known [1-5] and theyhave extensive technological applications,but the d-transition metal oxysulphides wasnot known until recently [6-9].Therefore,itis necessary to study the thermodynamicproperties of these compounds.
基金Project supported by the National Natural Science Foundation of China （Grant No 20673050）.
文摘This paper reports that low-temperature heat capacities of N-methylnorephedrine C11H17NO（s） have been measured by a precision automated adiabatic calorimeter over the temperature range from T=78K to T=400K. A solid to liquid phase transition of the compound was found in the heat capacity curve in the temperature range of T=342-364 K. The peak temperature, molar enthalpy and entropy of fusion of the substance were determined. The experimental values of the molar heat capacities in the temperature regions of T=78-342 K and T=364-400 K were fitted to two poly- nomial equations of heat capacities with the reduced temperatures by least squares method. The smoothed molar heat capacities and thermodynamic functions of N-methylnorephedrine C11H17NO（s） relative to the standard refer- ence temperature 298.15 K were calculated based on the fitted polynomials and tabulated with an interval of 5 K. The constant-volume energy of combustion of the compound at T=298.15 K was measured by means of an isoperibol precision oxygen-bomb combustion calorimeter. The standard molar enthalpy of combustion of the sample was calculated. The standard molar enthalpy of formation of the compound was determined from the combustion enthalpy and other auxiliary thermodynamic data through a Hess thermochemical cycle.
基金Supported by The Wenzhou Municipal Science and Technology Commission Major Projects Funds,No.20090006
文摘AIM: To assess the value of plasma melatonin in pre-dicting acute pancreatitis when combined with the acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) and bedside index for severity in acute pancreatitis (BISAP) scoring systems. METHODS: APACHEⅡ and BISAP scores were calculated for 55 patients with acute physiology (AP) in the first 24 h of admission to the hospital. Additionally, morning (6:00 AM) serum melatonin concentrations were measured on the first day after admission. According to the diagnosis and treatment guidelines for acute pancreatitis in China, 42 patients suffered mild AP (MAP). The other 13 patients developed severe AP (SAP). A total of 45 healthy volunteers were used in this study as controls. The ability of melatonin and the APACHEⅡ and BISAP scoring systems to predict SAP was evaluated using a receiver operating characteristic (ROC) curve. The optimal melatonin cutoff concentration for SAP patients, based on the ROC curve, was used to classify the patients into either a high concen-tration group (34 cases) or a low concentration group (21 cases). Differences in the incidence of high scores, according to the APACHEⅡ and BISAP scoring sys- tems, were compared between the two groups. RESULTS: The MAP patients had increased melatonin levels compared to the SAP (38.34 ng/L vs 26.77 ng/L) (P = 0.021) and control patients (38.34 ng/L vs 30.73 ng/L) (P = 0.003). There was no significant difference inmelatoninconcentrations between the SAP group and the control group. The accuracy of determining SAP based on the melatonin level, the APACHEⅡ score and the BISAP score was 0.758, 0.872, and 0.906, respectively, according to the ROC curve. A melatonin concentration ≤ 28.74 ng/L was associated with an increased risk of developing SAP. The incidence of high scores (≥ 3) using the BISAP system was significantly higher in patients with low melatonin concentration (≤ 28.74 ng/L) compared to patients with high melatonin concentration (> 28.74 ng/L) (42.9% vs 14.7%, P = 0.02). The incidence of high APACHEⅡ scores (≥ 10) between the two groups was not significantly different. CONCLUSION: The melatonin concentration is closely related to the severity of AP and the BISAP score. Therefore, we can evaluate the severity of disease by measuring the levels of serum melatonin.
文摘The Gibbs standard free energies of formation of the fluorides and the oxyfluorides of Y. Gd. Dy, Tb,Ho. Er and Yb were measured by using either a calcium concentration cell with Caβ' / β+x-Al_2O_3 solidelectrolyte or an oxygen concentration cell with calcia stabilized zirconia (CSZ) solid electrolyte, accordingto which the phase stability diagram of RE-O-F systems were determined.
