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1.
Lebedev B. V. Kulagina T. G. Smirnova N. N. Shifrina Z. B. Averina M. S. Rusanov A. L. 《Journal of Thermal Analysis and Calorimetry》2003,74(3):735-748
In an adiabatic vacuum calorimeter, the temperature dependence of the heat capacity C
p of phenylated polyphenylene and initial comonomer 1,4-bis(2,4,5-triphenylcyclopentadienone-3-yl)benzene was studied between
6 and 340 K with an uncertainty of about 0.2%. In a calorimeter with a static bomb and an isothermal shield their energies
of combustion DUcomb were measured. From the experimental data, the thermodynamic functions C
p
0 (T), H
0(T)-H
0(0), S
0(T)-S0(0), G
0(T)-H
0(0) were calculated from 0 to 340 K, and standard enthalpies of combustion ΔH
comb
0 and thermodynamic parameters of formation-enthalpies ΔH
f
0, entropies ΔH
f
0, Gibbs functions ΔG
f
0 - of the substances studied were estimated at T=298.15 K at standard pressure. The results were used to calculate the thermodynamic characteristics (ΔH
f
0 ,ΔS
f
0, ΔG
f
0) of phenylated polyphenylene synthesis in the range from 0 to 340 K.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Iwona Zięborak-Tomaszkiewicz P. Gierycz 《Journal of Thermal Analysis and Calorimetry》2008,93(3):693-699
The change of thermal functions (ΔH
0(T), ΔS
0(T), ΔG
0(T)) and formation functions (ΔH
f0(T), ΔG
f0(T), K
f(T)) with temperature for gallium nitride and indium nitride have been formulated based on the reliable experimental data obtained
by the use the same equipment in one laboratory. 相似文献
3.
Numerical values of the enthalpies of formation of oxygen-containing organic radicals of alcohol and ether derivatives (Δf
H°) were analyzed. For seven out of 25 compounds the corresponding Δf
H° values were determined more accurately. For 35 radicals, the Δf
H° values were determined for the first time based on the published values of bond dissociation energies in molecules and on
the corresponding enthalpies of their formation. Based on the analysis of the Δf
H° values for 60 radicals studied, a structure—property (enthalpy of formation) correlation was established, described in the
framework of the group additivity scheme. The parameters for calculations of Δf
H° values for the title radicals were recommended. 相似文献
4.
T. G. Kulagina Ya. S. Samosudova I. A. Letyanina E. V. Sevast’yanov N. N. Smirnova L. A. Smirnova A. E. Mochalova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(5):747-751
The temperature dependence of the heat capacity C
p
o= f(T) 2 of 2-ethylhexyl acrylate was studied in an adiabatic vacuum calorimeter over the temperature range 6–350 K. Measurement
errors were mainly of 0.2%. Glass formation and vitreous state parameters were determined. An isothermic shell calorimeter
with a static bomb was used to measure the energy of combustion of 2-ethylhexyl acrylate. The experimental data were used
to calculate the standard thermodynamic functions C
p
o(T), H
o(T)-H
o(0), S
o(T)-S
o(0), and G
o(T)-H
o(0) of the compound in the vitreous and liquid states over the temperature range from T → 0 to 350 K, the standard enthalpies of combustion Δc
H
o, and the thermodynamic characteristics of formation Δf
H
o, Δf
S
o, and Δf
G
o at 298.15 K and p = 0.1 MPa. 相似文献
5.
DTA and DSC were used to study the thermal behaviour of Ca(NO3)2·4H2O, Cd(NO3)2·4H2O, Mg(NO3)2·6H2O and their deuterated analogues. Evidence was found concerning the process of melting of the initial hydrates and deuterates,
followed by a one-stage dehydration of the melt to vield the respective anhydrous salt.
T
m, ΔH
m
o
, ΔS
m
o
and ΔH
deh
o
were determined and the ΔH
f
o
values for the investigated hydrates were calculated from the ΔH
deh
o
data.
Zusammenfassung DTA und DSC wurden zur Untersuchung des thermischen Verhaltens von Ca(NO3)2·4H2O, Cd(NO3)2·4H2O, Mg(NO3)2·6H2O und ihrer deuterierten Analoge eingesetzt. Man fand Aussagen bezüglich des Schmelzvorganges der Ausgangshydrate und Deuterate, gefolgt von einer Einschritt-Dehydratation der Schmelze unter Bildung der entsprechenden wasserfreien Salze. T m, ΔH m o , ΔS m o und ΔH deh o wurden ermittelt und die ΔH f o Werte für die untersuchten Hydrate wurden anhand der ΔH deh o berechnet.相似文献
6.
Digo Hermínio P. Pinto Susana S. Moura Ramos Joaquim J. 《Journal of Thermal Analysis and Calorimetry》2004,77(3):893-904
The thermal behaviour of salicylsalicylic acid (CAS number 552-94-3) was studied by differential scanning calorimetry (DSC).
The endothermic melting peak and the fingerprint of the glass transition were characterised at a heating rate of 10°C min-1. The melting peak showed an onset at T
on = 144°C (417 K) and a maximum intensity at T
max = 152°C (425 K), while the onset of the glass transition signal was at T
on = 6°C. The melting enthalpy was found to be ΔmH = 28.9±0.3 kJ mol-1, and the heat capacity jump at the glass transition was ΔC
P = 108.1±0.1 J K-1mol-1. The study of the influence of the heating rate on the temperature location of the glass transition signal by DSC, allowed
the determination of the activation energy at the glass transition temperature (245 kJ mol-1), and the calculation of the fragility index of salicyl salicylate (m = 45). Finally, the standard molar enthalpy of formation of crystalline monoclinic salicylsalicylic acid at T = 298.15 K, was determined as ΔfHm
o(C14H10O5, cr) = - (837.6±3.3) kJ mol-1, by combustion calorimetry.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
N. Wiegand L. Vámhidy B. Patczai E. Dömse P. Than L. Kereskai D. Lőrinczy 《Journal of Thermal Analysis and Calorimetry》2009,95(3):797-800
The Dupuytren contracture - degenerative shortening of the palmar aponeurosis - is a common disease of the hand in Europe.
The aetiology of the degenerative changes in the collagen structures is still not clear. To describe the clinical manifestation
of the disease we use an international classification according to Iselin. Our hypothesis was that in Dupuytren disease there
is a clear pathological abnormality in the tissue elements building up the palmar aponeurosis, which is responsible for the
disease, and could be monitored besides the classical histological methods by differential scanning calorimetry.
The thermal denaturation of different parts of human samples was monitored by a SETARAM Micro DSC-II calorimeter. All the
experiments were performed between 0 and 100°C. The heating rate was 0.3 K min−1. DSC scans clearly demonstrated significant differences between the different types and conditions of samples (control: T
m=63°C and ΔH
cal=4.1 J g−1, stage I.: T
m= 63°C and ΔH
cal=5.1 J g−1, stage II.: T
m=64°C and ΔH
cal=5.2 J g−1, stage III.: T
m=60°C and ΔH
cal=5.2 J g−1, stage IV.: T
m=60.2°C and ΔH
cal=5.3 J g−1). The heat capacity change between native and denatured states of aponeurosis samples increased with the degree of structural
alterations indicating significant water loosing. These observations could be explained with the structural alterations caused
by the biochemical processes.
With our investigations we could demonstrate that DSC is a useful and well applicable method for the investigation of collagen
tissue of the human aponeurosis. Our results may be of clinical relevance in the future i.e. in the choice of the optimal
time of surgical therapy of different clinical level Dupuytren contractures. 相似文献
8.
N. N. Smirnova T. A. Bykova V. N. Larina T. G. Kulagina A. D. Pomogailo G. I. Dzhardimalieva 《Polymer Science Series A》2010,52(4):349-355
The temperature dependences of the heat capacities of hydrated acrylamide and poly(acrylamide) complexes of cobalt nitrate
are studied via high-precision adiabatic calorimetry at 6 to 300–380 K. The energy of combustion is estimated via isothermic
calorimetry. This evidence makes it possible to calculate thermodynamic functions C
p
ℴ(T), H
ℴ(T) − H
ℴ(0), S
ℴ(T), G
ℴ(T) − H
ℴ(0) at 0 to 300–380 K; the standard enthalpy of combustion, ΔcH
ℴ; and the thermodynamic parameters of formation, Δ
f
H
ℴ, Δ
f
S
ℴ, and Δ
f
G
ℴ, of monomer and polymer complexes composed of simple compounds at 298.15 K. The results are used for the estimation of enthalpy
Δpol
H
ℴ, entropy Δpol
S
ℴ, and Gibbs function Δpol
G
ℴ of bulk polymerization for hydrated acrylamide complexes of cobalt nitrate at 0–300 K. 相似文献
9.
The aim of this work was to analyze the possible use of differential scanning calorimetry (DSC) as a method to study the process
of protein modifications during enzymatic hydrolysis. Results of the enzymatic hydrolysis of soy protein showed significant
differences in the values of maximum deflection temperature (T
p), heat of reaction (ΔH), and width at half peak height (ΔT
1/2), between DSC curves corresponding to the substrate, or zerotime of hydrolysis, and those of the hydrolysates obtained by
the action of cucurbita and pomiferin enzymes. DSC curve changes mentioned were explained by the use of gel-filtration chromatography, denaturing electrophoresis
and surface hydrophobicity of the hydrolysis products obtained at 30 min of reaction.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
N. N. Smirnova T. A. Bykova N. A. Polotnyanko N. D. Shikina I. L. Khodakovskii 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(11):1851-1855
The temperature dependence of the heat capacity C
p
o = f(T) of palladium oxide PdO(cr.) was studied for the first time in an adiabatic vacuum calorimeter in the range of 6.48–328.86
K. Standard thermodynamic functions C
p
o(T), H
o(T) — H
o(0), S
o(T), and G
o(T) — H
o(0) in the range of T → 0 to 330 K (key quantities in different thermodynamic calculations with the participation of palladium compounds) were
calculated on the basis of the experimental data. Based on an analysis of studies on determining the thermodynamic properties
of PdO(cr.), the following values of absolute entropy, standard enthalpy, and Gibbs function of the formation of palladium
oxide are recommended: S
o(298.15) = 39.58 ± 0.15 J/(K mol), Δf
H
o(298.15) = −112.69 ± 0.32 kJ/mol, Δf
G
o(298.15) = −82.68 ± 0.35 kJ/mol. The stability of Pd(OH)2 (amorph.) with respect to PdO(cr.) was estimated. 相似文献
11.
G. Bognár Cs. Pintér B. Horváth T. Sydo E. Ligeti J. Pulai D. Lőrinczy 《Journal of Thermal Analysis and Calorimetry》2009,95(3):769-774
Osteonecrosis (ON) of the femoral frequently occurs after steroid medication. One of the final pathways leading to steroid
induced ON is thought to be pathologic fat metabolism. The pathobiological mechanism underlying the induction of fat metabolism
outslides by steroids leading to ON has not been fully elucidated. The purpose of this study was to examine the intraoperative
obtained gluteal fat tissue from ON patients with histology, gas chromatography (GC) and differential scanning calorimetry
(DSC) and to compare them with otherwise healthy patient’s samples. The histological sections showed no significant differences
compared with the control group. GC revealed that fraction of saturated fatty acids decreased in ON samples from mean values
of controls of 24% to 21, the polyunsaturated fraction from 20 to 14%. The monounsaturated acids showed an increase from mean
rate of 52% of the controls to 65% of steroid treated samples. DSC curves correlate with chromatographic analysis of the tissue
fatty acids (Steroid treated, heating between 0–100°C: T
m=5.7°C, ΔH= −15.8J/g−1; heating between −20–100°C: Tm= −9.96 and 5.85°C, ΔH= −59.17 and −16.2 J g−1. Non-necrotic, heating between 0–100°C: two separable transition with Tm=5.7 and 9.9°C, total ΔH= −20.8 J g−1; heating between −20–100°C: Tm= −10.9 and 4.95°C, total ΔH= −75.8 J g−1.)
Our preliminary findings are rather tendentious. Further investigations are needed with higher sample rate and under other
anamnestic circumstances too. 相似文献
12.
K. A. Aly A. Dahshan Yasser B. Saddeek 《Journal of Thermal Analysis and Calorimetry》2010,100(2):543-549
The present paper reports on the effect of MoO3 on the glass transition, thermal stability and crystallization kinetics for (40PbO–20Sb2O3–40As2O3)100−x
–(MoO3)
x
(x = 0, 0.25, 0.5, 0.75 and 1 mol%) glasses. Differential scanning calorimetry (DSC) results under non-isothermal conditions
for the studied glasses were reported and discussed. The values of the glass transition temperature (T
g) and the peak temperature of crystallization (T
p) are found to be dependent on heating rate and MoO3 content. From the compositional dependence and the heating rate dependence of T
g and T
p, the values of the activation energy for glass transition (E
g) and the activation energy for crystallization (E
c) were evaluated and discussed. Thermal stability for (40PbO–20Sb2O3–40As2O3)100−x
–(MoO3)
x
glasses has been evaluated using various thermal stability criteria such as ΔT, H
r
, H
g and S. Moreover, in the present work, the K
r(T) criterion has been considered for the evaluation of glass stability from DSC data. The stability criteria increases with
increasing MoO3 content up to x = 0.5 mol%, and decreases beyond this limit. 相似文献
13.
Yanchun Li Yi Cheng Yinghua Ye Ruiqi Shen 《Journal of Thermal Analysis and Calorimetry》2010,102(2):605-608
The relative errors (e%) in the determination of the activation energy from the slope of the Kissinger straight line ln(β/βT
p2) vs. 1/T
p (β is the heating rate) are in-depth discussion. Our work shows that the relative errors is a function containing the factors
of x
p and Δx
p, not only x
p (x
p = E/RT
p, E is the activation energy, T
p is the temperature corresponding to maximum process rate, R is the gas constant). The relative error between E
k and E
p will be smaller with the increase of the value of x and/or with the decrease of the value of Δx. For a set of different heating rates in thermal analysis experiments, the low and close heating rates are proposed from
the kinetic theory. 相似文献
14.
The enthalpies of formation (ΔH
f
o) for 23 halosubstituted radicals were determined from the published data on bond dissociation energies. The ΔH
f
o values of the corresponding molecules necessary for the calculation of ΔH
f
o of the radicals were taken from handbooks or calculated by the additive-group method. The conjugation energies of the radicals
are calculated, and the effect of substituents at the π-system on these values was shown. Errors of determination of the ΔH
f
o values of the radicals were estimated.
For Part 1, see Ref. 1.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 643–646, April, 1998. 相似文献
15.
Yu. D. Orlov Yu. A. Lebedev L. G. Menchikov O. M. Nefedov 《Russian Chemical Bulletin》1997,46(1):52-58
Known enthalpies of formation (Δf
H
o) of carbenes in the ground state in the gas phase were analyzed; the prospects for the theoretical evaluation of (Δf
H
o) were considered. The (Δf
H
o) values of carbenes were calculated by the group-addition method, developed previously for free radicals, as well as by the
AM1 and PM3 quantum-chemical methods; these methods were compared.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 57–63, January, 1997. 相似文献
16.
Yu H. G. Yu Dong J. X. Qin C. Q. Liu Y. Qu S. S. 《Journal of Thermal Analysis and Calorimetry》2004,75(3):807-813
The energy of combustion of crystalline 3,4,5-trimethoxybenzoic acid in oxygen at T=298.15 K was determined to be -4795.9±1.3 kJ mol-1 using combustion calorimetry. The derived standard molar enthalpies of formation of 3,4,5-trimethoxybenzoic acid in crystalline
and gaseous states at T=298.15 K, ΔfHm
Θ (cr) and ΔfHm
Θ (g), were -852.9±1.9 and -721.7±2.0 kJ mol-1, respectively. The reliability of the results obtained was commented upon and compared with literature values.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
17.
The peak temperature (T
p) and different temperature (ΔT) are the basic information in the differential thermal analysis (DTA). Considering the kinetic relation and the heat equilibrium
in DTA, a correctional differential kinetic equation (containing T
p and ΔT parameter) is proposed. In the dehydration reaction of CaC2O4·H2O, the activation energy calculated from the new equation showed some smaller than that from Kissinger equation, but some
bigger than that from Piloyan equation. 相似文献
18.
The temperature dependence of heat capacity of C70 fullerene was studied by calorimetry in the range between 6 and 390 K. Phase transitions were established and their thermodynamic
characteristics were determined. From the experimental data obtained, the thermodynamic functionsH
o
(T)-H
o(0),S
o(T),G
o(T)-H
o(0) for temperatures between 0 and 390 K were calculated. The results were used to calculate the standard values of Δf
S
o, Δf
G
o, and logK
f
o
for the formation of C70 from graphite.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 647–650, April, 1998. 相似文献
19.
Yu. D. Orlov E. M. Chernova V. V. Turovtsev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(2):175-183
A collection of data on enthalpies of the formation(Δf
H
o) of aliphatic carbonyl-containing radicals is analyzed and expanded. The Δf
H
o values for 29 carbonyl-containing radicals are determined for the first time, and are strongly revised for 17 carbonyl-containing
radicals using the literature data on the dissociation energies of the bonds in molecules. The data is analyzed on the basis
of the structureproperty (enthalpy of formation) relation within the additive-group approach, with the determination and specification
of the parameters. It is concluded that the Δf
H
o values of carbonyl-containing radicals calculated from the obtained parameters (a total of 96 compounds was considered) agree
well with the experimental data. 相似文献
20.
Edwin H. Battley 《Journal of Thermal Analysis and Calorimetry》2011,104(1):13-22
Calculations are made using the equations Δr
G = Δr
H − TΔr
S and Δr
X = Δr
H − Δr
Q where Δr
X represents the free energy change when the exchange of absorbed thermal energy with the environment is represented by Δr
Q. The symbol Q has traditionally represented absorbed heat. However, here it is used specifically to represent the enthalpy listed in tabulations
of thermodynamic properties as (H
T
− H
0) at T = 298.15 K, the reason being that for a given substance TS equals 2.0 Q for solid substances, with the difference being greater for liquids, and especially gases. Since Δr
H can be measured, and is tangibly the same no matter what thermodynamics are used to describe a reaction equation, a change
in the absorbed heat of a biochemical growth process system as represented by either Δr
Q or TΔr
S would be expected to result in a different calculated value for the free energy change. Calculations of changes in thermodynamic
properties are made which accompany anabolism; the formation of anabolic, organic by-products; catabolism; metabolism; and
their respective non-conservative reactions; for the growth of Saccharomyces cerevisiae using four growth process systems. The result is that there is only about a 1% difference in the average quantity of free
energy conserved during growth using either Eq. 1 or 2. This is because although values of TΔr
S and Δr
Q can be markedly different when compared to one another, these differences are small when compared to the value for Δr
G or Δr
X. 相似文献