The kinetics of thermal decomposition of a series of uranyl nitrate complexes with N-alkylcaprolactams (alkyl=C2H5, C4H9, C6H13, C8H17, C10H21 or C12H25) was studied by means of non-isothermal gravimetry under a nitrogen atmosphere. From the TG-DTG curves, the kinetic parameters
relating to the loss of two molecules of coordinated ligand were obtained by employing two groups of methods: (I) a group
of conventional methods involving the Coast-Redfern, Freeman-Carroll, Horowitz-Metzger, Dharwadkar-Karkhanavala and Doyle
(modified by Zsakó) equations; (II) a new method were suggested by J. Máleket al.. The results obtained using two types of methods were compared, and it emerged that the results of method II were much more
meaningful and reasonable in this work. Additionally, the effects of the molecular structure of the ligands on the kinetic
data and models were studied and are discussed.
The molar heat capacities of the room temperature
ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF4)
were measured by an adiabatic calorimeter in temperature range from 80 to
390 K. The dependence of the molar heat capacity on temperature is given as
a function of the reduced temperature X
by polynomial equations, CP,m
(J K–1 mol–1)=
195.55+47.230 X–3.1533 X2+4.0733 X3+3.9126 X4 [X=(T–125.5)/45.5] for the solid phase (80~171
K), and CP,m (J
378.62+43.929 X+16.456 X2–4.6684 X3–5.5876 X4 [X=(T–285.5)/104.5] for the liquid phase (181~390
K), respectively. According to the polynomial equations and thermodynamic
relationship, the values of thermodynamic function of the BMIBF4
relative to 298.15 K were calculated in temperature range from 80 to 390 K
with an interval of 5 K. The glass translation of BMIBF4
was observed at 176.24 K. Using oxygen-bomb combustion calorimeter, the molar
enthalpy of combustion of BMIBF4 was determined to
– 5335±17 kJ mol–1. The standard
molar enthalpy of formation of BMIBF4 was evaluated
to be ΔfHmo=
–1221.8±4.0 kJ mol–1 at T=298.150±0.001 K.
The heat capacities of N-(tert-butoxycarbonyl)-l-phenylalanine (abbreviated to NTBLP in this article), as an important chemical intermediates used to synthesize proteins and polypeptides, were measured by means of a fully automated adiabatic calorimeter over the temperature range from 78 to 350 K. The measured experimental heat capacities were fitted to a polynomial equation as a function of temperature. The thermodynamic functions, HT − H298.15K and ST − S298.15K, were calculated based on the heat capacity polynomial equation in the temperature range of (80–350 K) with an interval of 5 K. The thermal stability of the compound was further studied using TG and DSC analyses; a possible mechanism for thermal decomposition of the compound was suggested.
Microcalorimetry was applied to study the toxic action of two cobalt compounds such as bis(salicylideniminato-3-propyl)methylaminocobalt(II)
(denoted as Co(II)) and Co(III) sepulchrate trichloride (denoted as Co(sep)3+) on (E. coli) DH5α. The power-time curves of the E. coli DH5α growth were determined, and the thermokinetics parameters such as the growth rate constant k, the maximum power output Pm and the time (tm) corresponding to the Pm were obtained. The half-inhibitory concentrations (IC50) of Co(II) and Co(sep)3+ to E. coli DH5α were 15 and 42.1 mg mL−1, respectively.
The experimental results revealed that the toxicity of the Co(II) compound was larger than that of Co(sep)3+. On the other hand, the scanning electron microscopy (SEM) demonstrated that the two cobalt compounds had the same toxic
mechanism on E. coli DH5α, which was attributed to the damage of cell wall of the bacteria caused by both Co(II) and Co(sep)3+. Furthermore, accumulation of intracellular cobalt of E. coli DH5α, due to the interaction of Co(II) or Co(sep)3+ and E. coli DH5α, has been found by using inductively coupled plasma (ICP) analytical technique.
Authors:L. Yang, F. Xu, L. Sun, Z. Zhao, and C. Song
Microcalorimetry was applied to study the effect of cephalosporins (cefazolin sodium and cefonicid sodium) on the E. coli growth. The microbial activity was recorded as power-time curves through an ampoule method with a TAM Air Isothermal Microcalorimeter
at 37°C. The parameters such as the growth rate constant (k), inhibitory ratio (I), the maximum power output (Pm) and the time corresponding to the maximum power output (tm) were calculated. The change tendencies of k, with the increasing of concentration (C) of the two cephalosporins, are similar which show that cefazolin sodium and cefonicid sodium have the same inhibitory mechanism.
The experimental results reveal that cefonicid sodium has a stronger antibacterial activity towards E. coli than that of cefazolin sodium and this was coincide with the clinical manifestations.
Authors:J. Zeng, Z. Cao, D. Yang, L. Sun, and L. Zhang
One of the greatest challenges in the application of organic phase change materials (PCMs) is to increase their thermal conductivity
while maintaining high phase change enthalpy. 1-Tetradecanol/Ag nanowires composite PCM containing 62.73 wt% (about 11.8 vol%)
of Ag nanowires showed remarkably high thermal conductivity (1.46 W m−1 K−1) and reasonably high phase change enthalpy (76.5 J g−1). This behavior was attributed to the high aspect ratio of Ag nanowires, few thermal conduct interfaces, and high interface
thermal conductivity of Ag nanowires in the composite PCM. These results indicated that Ag nanowires might be strong candidates
for thermal conductivity enhancement of organic PCMs.
Authors:X. Liu, H. Zhang, Z. Tan, K. Han, and L. Sun
The isoquinoline alkaloids were isolated from traditional Chinese drugs of Phellodendri Cortex, Radix Stephaniae Tetrandrae,
Corydalis Yanhusuo and Corydalis Bungeana. The power-time curves of growth of E. coli at different concentrations of isoquinoline alkaloid at 37�C were determined by a 2277 Thermal Activity Monitor. The rate
constant of bacteriostastic activity was calculated. The relationship between growth rate constant and concentration was established.
The optimum bacteriostastic concentration was determined. Experimental results have indicated that all the isoquinoline alkaloids
isolated from the four kinds of traditional Chinese drugs have bacteriostastic activity and the order is Phellodendri Cortex>Radix
Stephaniae Tetrandrae>Corydalis Yanhusuo>Corydalis Bungeana.
A complex of neodymium perchloric acid coordinated with L-glutamic acid and imidazole, [Nd(Glu)(H2O)5(Im)3](ClO4)6·2H2O was synthesized and characterized by IR and elements analysis for the first time. The thermodynamic properties of the complex
were studied with an automatic adiabatic calorimeter and differential scanning calorimetry (DSC). Glass transition and phase
transition were discovered at 221.83 and 245.45 K, respectively. The glass transition was interpreted as a freezing-in phenomenon
of the reorientational motion of ClO4− ions and the phase transition was attributed to the orientational order/disorder process of ClO4− ions. The heat capacities of the complex were measured with the automatic adiabatic calorimeter and the thermodynamic functions
[HT-H298.15] and [ST-S298.15] were derived in the temperature range from 80 to 390 K with temperature interval of 5 K. Thermal decomposition behavior
of the complex in nitrogen atmosphere was studied by thermogravimetric (TG) analysis and differential scanning calorimetry
The molar heat capacity Cp,m of 1,2-cyclohexane dicarboxylic anhydride was measured in the temperature range from T=80 to 390 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 303.80 K, 14.71 kJ mol−1 and 48.43 J K−1 mol−1, respectively. The thermodynamic functions [HT-H273.15] and [ST-S273.15] were derived in the temperature range from T=80 to 385 K with temperature interval of 5 K. The thermal stability of the compound was investigated by differential scanning
calorimeter (DSC) and thermogravimetry (TG), when the process of the mass-loss was due to the evaporation, instead of its