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1.
This work reports the thermoluminescence characterization of newly synthesized Li2B4O7 (LTB) and LTB:Cu materials of single crystal and glassy structure. The following basic properties were investigated: glow curve, dose response, fading, reproducibility and batch uniformity. The Cu doped samples and the non-doped single crystal gave TL response, while the non-doped glassy LTB did not up to 10 kGy. LTB:Cu single crystals showed promising properties. Their glow curve consists of two well separated peaks (at 165 °C and 270 °C) in the 50–350 °C temperature region. The sensitivity of this material is about 5 times higher than that of the TLD-100. The most attractive feature of these LTB:Cu single crystals is their linear dose response in a very wide range: from 0.3 mGy to 10 kGy. Unfortunately this material is sensitive to light; the fading of irradiated samples is very quick in daylight, but at room temperature and kept in dark the fading of the 270 °C peak is less than 6%.  相似文献   

2.
3.
Densities of aqueous solutions with molalities up to 6 mol · kg−1 were determined at 5 K temperature intervals, from T = 288.15 K to T = 333.15 K. Densities served to evaluate the apparent molar volumes, V2,ϕ(m, T), the cubic expansion coefficients, α(m, T), and the changes of isobaric heat capacities with respect to pressure, (∂CP/∂P)T,m. They were qualitatively correlated with the changes in the structure of water when glutaric acid is dissolved in it.  相似文献   

4.
We have measured the densities of aqueous solutions of l-methionine, l-methionine plus equimolal HCl, and l-methionine plus equimolal NaOH at temperatures 278.15  T/K  368.15, at molalities 0.0125  m/mol · kg−1  1.0 as solubilities allowed, and at p = 0.35 MPa using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15  T/K  393.15 and at the same m and p using a twin fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes Vϕ and the heat capacities to calculate apparent molar heat capacities Cp,ϕ for these solutions. We used our results and values from the literature for Vϕ(T, m) and Cp,ϕ(T, m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change ΔrCp,m(T, m) for ionization of water to calculate parameters for ΔrCp,m(T, m) for the two proton dissociations from protonated aqueous cationic l-methionine. We integrated these results in an iterative algorithm using Young’s Rule to account for the effects of speciation and chemical relaxation on Vϕ(T, m) and Cp,ϕ(T, m). This procedure yielded parameters for Vϕ(T, m) and Cp,ϕ(T, m) for methioninium chloride {H2Met+Cl(aq)} and for sodium methioninate {Na+Met(aq)} which successfully modeled our observed results. Values are given for ΔrCp,m, ΔrHm, pQa, ΔrSm, and ΔrVm for the first and second proton dissociations from protonated aqueous l-methionine as functions of T and m.  相似文献   

5.
In adiabatic low-pressure and dynamic calorimeters the temperature dependence of the standard molar heat capacity Cp, moof dibenzo- p -dioxin and 1,2,3,4-tetrachlorodibenzo- p -dioxin have been determined at temperatures in the range T =  5 K to T =  490 K: from T =  5 K to T =  340 K with an accuracy of about 0.2 per cent and with an accuracy of 0.5 per cent to 1.5 per cent between T =  340 K and T =  490 K. The temperatures, enthalpies, and entropies of melting of the above compounds have been determined. The experimental data were used to calculate the thermodynamic functions Cp, mo / R, Δ0THmo / (R·K), Δ0TSmo / R, and Φmo = Δ0TSmo  Δ0THmo / T(where R is the universal gas constant) in the range T   0 to T =  490 K. The isochoric heat capacity CV, mof both dioxins has been estimated over the range T   0 to Tfus. The effect of substitution of four hydrogen atoms by chlorine atoms on the lattice and atomic components of the isochoric heat capacity was considered.  相似文献   

6.
We have measured the densities of aqueous solutions of isoleucine, threonine, and equimolal solutions of these two amino acids with HCl and with NaOH at temperatures 278.15  T/K  368.15, at molalities 0.01  m/mol · kg−1  1.0, and at the pressure 0.35 MPa using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15  T/K  393.15 and at the same m and p using a twin fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes Vϕ and the heat capacities to calculate apparent molar heat capacities Cp,ϕ for these solutions. We used our results and values from the literature for Vϕ(T, m) and Cp,ϕ(T, m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change ΔrCp,m(T, m) for ionization of water to calculate parameters for ΔrCp,m(T, m) for the two proton dissociations from each of the protonated aqueous cationic amino acids. We used Young’s Rule and integrated these results iteratively to account for the effects of equilibrium speciation and chemical relaxation on Vϕ(T, m) and Cp,ϕ(T, m). This procedure gave parameters for Vϕ(T, m) and Cp,ϕ(T, m) for threoninium and isoleucinium chloride and for sodium threoninate and isoleucinate which modeled our observed results within experimental uncertainties. We report values for ΔrCp,m, ΔrHm, pQa, ΔrSm, and ΔrVm for the first and second proton dissociations from protonated aqueous threonine and isoleucine as functions of T and m.  相似文献   

7.
The temperature dependence of the standard molar heat capacity Cp, moof samples of crystalline tetraphenylphosphonium perchlorate and tetraphenylarsonium perchlorate was measured in an adiabatic low-pressure calorimeter between T =  4.8 K and T =  340 K and from T =  5.8 K to T =  340 K, respectively, mostly to within a precision of 0.2 per cent. For tetraphenylphosphonium perchlorate, an anomalous change of the heat capacity in the range T =  125 K to T =  185 K, probably arising from the excitation of hindered rotations of atomic groups, was found and its thermodynamic characteristics were determined. No such anomaly was observed for tetraphenylarsonium perchlorate. The data obtained were used to calculate the thermodynamic functions Cp, mo(T) / R, Δ0THmo / R·K, Δ0TSmo / R, and Φmo = Δ0TSmo  Δ0THmo / T(where R is the universal gas constant) of the compounds between T   0 and T =  340 K.  相似文献   

8.
The Knudsen mass-loss effusion technique was used to measure the vapour pressures at different temperatures of the following six compounds: 2-methyl-3-nitrobenzoic acid, between T =  357.16 K and T =  371.16 K; 2-methyl-6-nitrobenzoic acid, between T =  355.16 K and T =  369.16 K; 3-methyl-2-nitrobenzoic acid, between T =  371.16 K and T =  385.14 K; 3-methyl-4-nitrobenzoic acid, between T =  363.21 K and T =  379.16 K; 4-methyl-3-nitrobenzoic acid, between T =  363.10 K and T =  377.18 K; 5-methyl-2-nitrobenzoic acid, between T =  355.18 K and T =  371.08 K. From the temperature dependence of the vapour pressure, the standard molar enthalpies of sublimation were derived by the Clausius–Clapeyron equation and the molar entropies of sublimation at equilibrium pressures were calculated. Using estimated values for the heat capacity differences between the gas and the crystal phases of the studied compounds the standard, po =  105Pa, molar enthalpies ΔcrgHmo, entropies ΔcrgSmoand Gibbs energies ΔcrgGmoof sublimation at T =  298.15 K, were derived:  相似文献   

9.
We have measured the densities of aqueous solutions of alanine, alanine plus equimolal HCl, and alanine plus equimolal NaOH at temperatures 278.15  T/K  368.15, at molalities 0.0075  m/mol · kg−1  1.0, and at the pressure p = 0.35 MPa using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15  T/K  393.15 and at the same m and p using a twin fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes Vϕ and the heat capacities to calculate apparent molar heat capacities Cp,ϕ for these solutions. We used our results and values from the literature for Vϕ(T, m) and Cp,ϕ(T, m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change ΔrCp,m(T, m) for ionization of water to calculate parameters for ΔrCp,m(T, m) for the two proton dissociations from protonated aqueous cationic alanine. We integrated these results in an iterative algorithm using Young’s Rule to account for the effects of speciation and chemical relaxation on Vϕ(T, m) and Cp,ϕ(T, m). This procedure yielded parameters for Vϕ(T, m) and Cp,ϕ(T, m) for alaninium chloride {H2Ala+Cl(aq)} and for sodium alaninate {Na+Ala(aq)} which successfully modeled our observed results. Values are given for ΔrCp,m, ΔrHm, pQa, ΔrSm, and ΔrVm for the first and second proton dissociations from protonated aqueous alanine as functions of T and m.  相似文献   

10.
The molar heat capacity Cp,m of 1-cyclohexene-1,2-dicarboxylic anhydride was measured in the temperature range from T=(80 to 360) K with a small sample automated adiabatic calorimeter. The melting point Tm, the molar enthalpy ΔfusHm and the entropy ΔfusSm of fusion for the compound were determined to be (343.46 ± 0.24) K, (11.88 ± 0.02) kJ · mol−1 and (34.60 ± 0.06) J · K−1 · mol−1, respectively. The thermodynamic functions [H(T)H(298.15)] and [S(T)S(298.15)] were derived in the temperature range from T=(80 to 360) K with temperature interval of 5 K. The mass fraction purity of the sample used in the adiabatic calorimetric study was determined to be 0.9928 by using the fractional melting technique. The thermal stability of the compound was investigated by differential scanning calorimeter (DSC) and thermogravimetric (TG) technique, and the process of the mass-loss of the sample was due to the evaporation, instead of its thermal decomposition.  相似文献   

11.
We determined apparent molar volumes V? at 298.15 ? (T/K) ? 368.15 and apparent molar heat capacities Cp,? at 298.15 ? (T/K) ? 393.15 for aqueous solutions of HIO3 at molalities m from (0.015 to 1.0) mol · kg?1, and of aqueous KIO3 at molalities m from (0.01 to 0.2) mol · kg?1 at p = 0.35 MPa. We also determined V? at the same p and at 298.15 ? (T/K) ? 368.15 for aqueous solutions of KI at m from (0.015 to 7.5) mol · kg?1. We determined Cp,? at the same p and at 298.15 ? (T/K) ? 393.15 for aqueous solutions of KI at m from (0.015 to 5.5) mol · kg?1, and for aqueous solutions of NaIO3 at m from (0.02 to 0.15) mol · kg?1. Values of V? were determined from densities measured with a vibrating-tube densimeter, and values of Cp,? were determined with a twin fixed-cell, differential temperature-scanning calorimeter. Empirical functions of m and T were fitted to our results for each compound. Values of Ka, ΔrHm, and ΔrCp,m for the proton ionization reaction of aqueous HIO3 are calculated and discussed.  相似文献   

12.
The (p, ρ, T) measurements and visual observations of the meniscus for propane were carried out carefully in the critical region over the range of temperatures: ?60 mK ? (T ? Tc) ?  40 mK and of densities: ?4 kg · m?3 ? (ρ ? ρc) ? 6 kg · m?3 by a metal-bellows volumometer with an optical cell. Vapour pressures were also measured at T = (320.000, 343.132, 369.000, and 369.625) K. The critical point of Tc, ρc, and pc was determined by the image analysis of the critical opalescence. Comparisons of the critical parameters with values given in the literature are presented.  相似文献   

13.
Molar enthalpies of dilution ΔdilHmofNa2CO3(aq) were measured from molality m =  1.45 mol · kg  1to m =  0.008 mol · kg  1at seven temperatures from T =  298 K toT =  523 K at the pressure p =  7 MPa, and at four temperatures fromT =  371 K to T =  523 K at the pressurep =  40 MPa. Molar enthalpies of dilutionΔdilHm of NaHCO3(aq) were measured fromm =  0.98 mol · kg  1tom =  0.007 mol · kg  1at the same temperatures and pressures. Hydrolysis and ionization equilibria contribute substantially to the measured enthalpies under many of the conditions of this study. Explicit consideration of these reactions, using thermodynamic quantities from previous studies, facilitates a quantitative representation of apparent molar enthalpies, activity coefficients, and osmotic coefficients with the Pitzer ion-interaction treatment over the ranges of temperature, pressure, and molality of the experiments.  相似文献   

14.
We have measured the densities of aqueous solutions of glycine, glycine plus equimolal HCl, and glycine plus equimolal NaOH at temperatures 278.15  T/K  368.15, molalities 0.01  m/mol · kg−1  1.0, and at p = 0.35 MPa, using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15  T/K  393.15 and at the same m and p using a fixed-cell differential scanning calorimeter. We used the densities to calculate apparent molar volumes Vϕ and the heat capacities to calculate apparent molar heat capacities Cp,ϕ for these solutions. We used our results and values of Vϕ(T, m) and Cp,ϕ(T, m) for HCl(aq), NaOH(aq), NaCl(aq) from the literature to calculate parameters for ΔrCp,m(T, m) for the first and second proton dissociations from protonated aqueous cationic glycine. We then integrated this value of ΔrCp,m(T, m) in an iterative algorithm, using Young’s Rule to account for the effects of speciation and chemical relaxation on the observed Vϕ and Cp,ϕ of the solutions. This procedure yielded parameters for Vϕ(T, m) and Cp,ϕ(T, m) for glycinium chloride {H2Gly+Cl(aq)} and sodium glycinate {Na+Gly(aq)} which successfully modeled our observed results. We have then calculated values of ΔrCp,m, ΔrHm, ΔrVm, and pQa for the first and second proton dissociations from protonated aqueous glycine as functions of T and m.  相似文献   

15.
Vapour pressures of water over saturated solutions of cesium chloride, cesium bromide, cesium nitrate, cesium sulfate, cesium formate, and cesium oxalate were determined as a function of temperature. These vapour pressures were used to evaluate the water activities, osmotic coefficients and molar enthalpies of vapourization. Molar enthalpies of solution of cesium chloride, ΔsolHm(T = 295.73 K; m = 0.0622 mol · kg−1) = (17.83 ± 0.50) kJ · mol−1; cesium bromide, ΔsolHm(T = 293.99 K; m = 0.0238 mol · kg−1) = (26.91 ± 0.59) kJ · mol−1; cesium nitrate, ΔsolHm(T = 294.68 K; m = 0.0258 mol · kg−1) = (37.1 ± 2.3) kJ · mol−1; cesium sulfate, ΔsolHm(T = 296.43 K; m = 0.0284 mol · kg−1) = (16.94 ± 0.43) kJ · mol−1; cesium formate, ΔsolHm(T = 295.64 K; m = 0.0283 mol · kg−1) = (11.10 ± 0.26) kJ · mol−1 and ΔsolHm(T = 292.64 K; m = 0.0577 mol · kg−1) = (11.56 ± 0.56) kJ · mol−1; and cesium oxalate, ΔsolHm(T = 291.34 K; m = 0.0143 mol · kg−1) = (22.07 ± 0.16) kJ · mol−1 were determined calorimetrically. The purity of the chemicals was generally greater than 0.99 mass fraction, except for HCOOCs and (COOCs)2 where purities were approximately 0.95 and 0.97 mass fraction, respectively. The uncertainties are one standard deviations.  相似文献   

16.
Apparent molar volumes Vϕ and apparent molar heat capacities Cp,ϕ were determined at the pressure 0.35 MPa for aqueous solutions of magnesium nitrate Mg(NO3)2 at molalities m = (0.02 to 1.0) mol · kg−1, strontium nitrate Sr(NO3)2 at m = (0.05 to 3.0) mol · kg−1, and manganese nitrate Mn(NO3)2 at m = (0.01 to 0.5) mol · kg−1. Our Vϕ values were calculated from solution densities obtained at T = (278.15 to 368.15) K using a vibrating-tube densimeter, and our Cp,ϕ values were calculated from solution heat capacities obtained at T = (278.15 to 393.15) K using a twin fixed-cell, differential, temperature-scanning calorimeter. Empirical functions of m and T were fitted to our results, and standard state partial molar volumes and heat capacities were obtained over the ranges of T investigated.  相似文献   

17.
The complexes of [Ln(2,3,4-tmoba)3phen]2 (Ln = Dy (1), Eu (2), Tb (3); 2,3,4-tmoba = 2,3,4-trimethoxybenzoate; phen = 1,10-phenanthroline) were synthesized and characterized by a series of techniques including the elemental analysis, IR and fluorescent spectra and TG/DSC-FTIR technology. The crystal structures were determined by X-ray crystallography. Each complex include two Ln3+ ions, six 2,3,4-tmoBA and two phen molecules forming a binuclear structure, giving the coordination number of nine. The three-dimensional IR accumulation spectra of gaseous products for the complexes 1 to 3 are analyzed and the thermal decomposition processes are further authenticated. Through means of differential scanning calorimeter (DSC), two solid-solid phase transition endothermic peaks were found in the complex 2, which was different from the complexes 1 and 3. The heat capacities of these complexes were measured and fitted to a polynomial equation with the least squares method for each complex on the basis of the reduce temperature x (x = [T  (Tmax + Tmin)/2]/[(Tmax  Tmin)/2]) over the range from (256.15 to 476.15) K. Subsequently, the smoothed molar heat capacities and thermodynamic functions (HTH298.15 K), (STS298.15 K), and (GTG298.15 K) of the complexes 1 to 3 were calculated based on the fitted polynomial of the heat capacities. The fluorescent intensity of the complexes 2 and 3 are markedly improved as well.  相似文献   

18.
We have measured the densities of aqueous solutions of serine, serine plus equimolal HCl, and serine plus equimolal NaOH at temperatures 278.15  T/K  368.15, molalities 0.01  m/mol · kg−1  1.0, and at the pressure p = 0.35 MPa, using a vibrating tube densimeter. We have also measured the heat capacities of these solutions at 278.15  T/K  393.15 and at the same m and p using a fixed-cell differential temperature-scanning calorimeter. We used the densities to calculate apparent molar volumes Vϕ and the heat capacities to calculate apparent molar heat capacities Cp,ϕ for these solutions. We used our results and values from the literature for Vϕ(T,m) and Cp,ϕ(T,m) for HCl(aq), NaOH(aq), and NaCl(aq) and the molar heat capacity change ΔrCp,m(T,m) for ionization of water to calculate ΔrCp,m(T,m) for proton dissociations from protonated aqueous cationic serine and from the zwitterionic form. We integrated these results in an iterative algorithm using Young’s rule to account for the effects of speciation and chemical relaxation on the observed Vϕ(T,m) and Cp,ϕ(T,m) of the solutions. This procedure yielded parameters for Vϕ(T,m) and Cp,ϕ(T,m) for serinium chloride {H2Ser+Cl(aq)} and for sodium serinate {Na+Gly(aq)} which successfully modeled our observed results. We have then calculated ΔrCp,m, ΔrHm, ΔrVm and pQa for the first and second proton dissociations from protonated aqueous serine as functions of T and m.  相似文献   

19.
Isothermal (vapour  +  liquid) equilibria were measured for (trichloromethane  +  tetrahydropyran or piperidine) at T =  333.15 K and {1-bromo-1-chloro-2,2,2-trifluoroethane (halothane)  +  tetrahydropyran or piperidine} atT =  323.15 K with a circulation still. The results were verified by effective statistical procedures and used to calculate activity coefficients and excess molar Gibbs free energiesGmE . Excess molar enthalpiesHmE for these mixtures were determined at T =  298.15 K by means of an isothermal CSC microcalorimeter equipped with recently reconstructed flow mixing cells. Reliable performance of the calorimetric setup was proved by the good agreement of HmEfor (hexane  +  cyclohexane), (2-propanone  +  water), and (methanol  +  water), with the best literature results. The trichloromethane- or halothane-containing mixtures exhibit strong negative deviations from Raoult’s law and are highly exothermic, thus indicating that complex formation via hydrogen bonding is a governing nonideality effect. A close similarity in the behaviour of corresponding mixtures with trichloromethane and halothane is observed, but for halothane-containing mixtures,GmE and HmEare consistently more negative, confirming that halothane is a more powerful proton donor than chloroform.  相似文献   

20.
In this study, gold nanoparticles (AuNPs) were green synthesized using plant extract. The obtained nanoparticles (Au NPs) were characterized by advanced physical and chemical techniques like TEM, FTIR, UV–vis, SEM, XRD and EDX. SEM image displayed the quasi-spherical shaped nanoparticles of mean diameter 20–50 nm. All the particles were of uniform shape and texture. From the XRD pattern, four distinct diffraction peaks at 38.2°, 44.2°, 64.7° and 77.4° are indexed as (1 1 1), (2 0 0), (2 2 0) and (3 1 1) planes of fcc metallic gold. The in vitro cytotoxic and anti-gastric carcinoma effects of biologically synthesized Au NPs against cancer cell lines were assessed. The IC50 of the Au NPs were 192, 149, 76 and 85 µg/mL against NCI-N87, MKN45, GC1401 and GC1436 gastric cancer cell lines. The anti-gastric carcinoma properties of the Au NPs could significantly remove the cancer cell lines in a time and concentration-dependent manner. So, the findings of the recent research show that biologically synthesized Au NPs might be used to cure cancer.  相似文献   

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