This study is concerned with describing the thermodynamic equilibrium of the saturated fluid with and without a free surface area A. Discussion of the role of A as system variable of the interface phase and an estimat...This study is concerned with describing the thermodynamic equilibrium of the saturated fluid with and without a free surface area A. Discussion of the role of A as system variable of the interface phase and an estimate of the ratio of the respective free energies of systems with and without A show that the system variables given by Gibbs suffice to describe the volumetric properties of the fluid. The well-known Gibbsian expressions for the internal energies of the two-phase fluid, namely for the vapor and for the condensate (liquid or solid), only differ with respect to the phase-specific volumes and . The saturation temperature T, vapor presssure p, and chemical potential are intensive parameters, each of which has the same value everywhere within the fluid, and hence are phase-independent quantities. If one succeeds in representing as a function of and , then the internal energies can also be described by expressions that only differ from one another with respect to their dependence on and . Here it is shown that can be uniquely expressed by the volume function . Therefore, the internal energies can be represented explicitly as functions of the vapor pressure and volumes of the saturated vapor and condensate and are absolutely determined. The hitherto existing problem of applied thermodynamics, calculating the internal energy from the measurable quantities T, p, , and , is thus solved. The same method applies to the calculation of the entropy, chemical potential, and heat capacity.展开更多
Our study aims to determine diagnostic reference levels (DRL) for chest front examination in postero anterior (PA) for optimizing patient entrance surface dose (ESD) and dose-area product (DAP) of patients in west of ...Our study aims to determine diagnostic reference levels (DRL) for chest front examination in postero anterior (PA) for optimizing patient entrance surface dose (ESD) and dose-area product (DAP) of patients in west of Côte d’Ivoire. 90 patients from three hospitals undergoing conventional radiology were considered. The ESD and DAP for each patient were obtained during chest radiography (PA) examination. The measurements were performed with the device call Dose-Area Product-meter (DAP-meter) with brand Diamentor M4-KDK, type 11017. The DRL were obtained in applying the 75th percentile statistical method to the obtained ESD and DAP. The obtained DRL in ESD for chest radiography for all rooms is 0.40 mGy and in DAP is 54.85 cGy·cm2. Our DRL for ESD is higher than those obtained in Abidjan District and in other countries like UK and Cameroon. Our DRL for DAP is higher than those from Abidjan and all other countries for which a similar study was made. The comparison of these values to those from Abidjan and other countries, shows us that radiology technicians can make efforts to choose radiological parameters to reduce ESD. They must use convenable the X-rays tube to reduce DAP by reducing the patient exposure surface.展开更多
In this research,the structural characteristics,specific surface area,sorption of water vapor,and wetting enthalpy of various polysaccharides(cellulose,hemicelluloses,starch,pectin,chitin,and chitosan)have been studie...In this research,the structural characteristics,specific surface area,sorption of water vapor,and wetting enthalpy of various polysaccharides(cellulose,hemicelluloses,starch,pectin,chitin,and chitosan)have been studied.It was confirmed that crystallites are inaccessible for water,and therefore water molecules can interact only with polar groups in noncrystalline(amorphous)domains of biopolymers.The isotherms of water vapor sorption for various polysaccharides had sigmoid shapes,which can be explained by the absorption of water molecules in heterogeneous amorphous domains having clusters with different packing densities.The method of contributions of polar groups to sorption of water molecules was used,which allowed to derivate a simple calculating equation to describe the shape of sorption isotherms.The wetting of biopolymers with water was accompanied by a high exothermic thermal effect,in direct proportion to the amorphicity degree.The sorption values and wetting enthalpies of amorphous domains of biopolymers were calculated,which allowed to find the hydrophilicity index and compare the hydrophilicity of the various polysaccharides.展开更多
文摘This study is concerned with describing the thermodynamic equilibrium of the saturated fluid with and without a free surface area A. Discussion of the role of A as system variable of the interface phase and an estimate of the ratio of the respective free energies of systems with and without A show that the system variables given by Gibbs suffice to describe the volumetric properties of the fluid. The well-known Gibbsian expressions for the internal energies of the two-phase fluid, namely for the vapor and for the condensate (liquid or solid), only differ with respect to the phase-specific volumes and . The saturation temperature T, vapor presssure p, and chemical potential are intensive parameters, each of which has the same value everywhere within the fluid, and hence are phase-independent quantities. If one succeeds in representing as a function of and , then the internal energies can also be described by expressions that only differ from one another with respect to their dependence on and . Here it is shown that can be uniquely expressed by the volume function . Therefore, the internal energies can be represented explicitly as functions of the vapor pressure and volumes of the saturated vapor and condensate and are absolutely determined. The hitherto existing problem of applied thermodynamics, calculating the internal energy from the measurable quantities T, p, , and , is thus solved. The same method applies to the calculation of the entropy, chemical potential, and heat capacity.
文摘Our study aims to determine diagnostic reference levels (DRL) for chest front examination in postero anterior (PA) for optimizing patient entrance surface dose (ESD) and dose-area product (DAP) of patients in west of Côte d’Ivoire. 90 patients from three hospitals undergoing conventional radiology were considered. The ESD and DAP for each patient were obtained during chest radiography (PA) examination. The measurements were performed with the device call Dose-Area Product-meter (DAP-meter) with brand Diamentor M4-KDK, type 11017. The DRL were obtained in applying the 75th percentile statistical method to the obtained ESD and DAP. The obtained DRL in ESD for chest radiography for all rooms is 0.40 mGy and in DAP is 54.85 cGy·cm2. Our DRL for ESD is higher than those obtained in Abidjan District and in other countries like UK and Cameroon. Our DRL for DAP is higher than those from Abidjan and all other countries for which a similar study was made. The comparison of these values to those from Abidjan and other countries, shows us that radiology technicians can make efforts to choose radiological parameters to reduce ESD. They must use convenable the X-rays tube to reduce DAP by reducing the patient exposure surface.
文摘In this research,the structural characteristics,specific surface area,sorption of water vapor,and wetting enthalpy of various polysaccharides(cellulose,hemicelluloses,starch,pectin,chitin,and chitosan)have been studied.It was confirmed that crystallites are inaccessible for water,and therefore water molecules can interact only with polar groups in noncrystalline(amorphous)domains of biopolymers.The isotherms of water vapor sorption for various polysaccharides had sigmoid shapes,which can be explained by the absorption of water molecules in heterogeneous amorphous domains having clusters with different packing densities.The method of contributions of polar groups to sorption of water molecules was used,which allowed to derivate a simple calculating equation to describe the shape of sorption isotherms.The wetting of biopolymers with water was accompanied by a high exothermic thermal effect,in direct proportion to the amorphicity degree.The sorption values and wetting enthalpies of amorphous domains of biopolymers were calculated,which allowed to find the hydrophilicity index and compare the hydrophilicity of the various polysaccharides.
