Search Results
You are looking at 11 - 20 of 41 items for
- Author or Editor: F. Zhao x
- Refine by Access: All Content x
Abstract
The decomposition reaction kinetics of the double-base (DB) propellant (No. TG0701) composed of the mixed ester of triethyleneglycol dinitrate (TEGDN) and nitroglycerin (NG) and nitrocellulose (NC) with cerium(III) citrate (CIT-Ce) as a combustion catalyst was investigated by high-pressure differential scanning calorimetry (PDSC) under flowing nitrogen gas conditions. The results show that pressure (2 MPa) can decrease the peak temperature and increase the decomposition heat, and also can change the mechanism function of the exothermal decomposition reaction of the DB gun propellant under 0.1 MPa; CIT-Ce can decrease the apparent activation energy of the DB gun propellant by about 35 kJ mol−1 under low pressure, but it can not display the effect under high pressure; CIT-Ce can not change the decomposition reaction mechanism function under a pressure.
Abstract
To increase the tumor uptake of Val-Gly-Gly (VGG), adenine was introduced into the peptide. N-mercaptoacetyl-VGG-adenine (MAVGG-adenine) and MAVGG were labeled with 99mTc using a solution of SnCl2 and tartaric acid as reducing agent. Biodistribution in mice bearing the S180 tumor was measured and γ imaging was performed. Compared with MAVGG, adenine conjugated MAVGG had higher tumor uptake and tumor to normal tissue ratios, which suggested that the tumor uptake property of a peptide may be improved by introducing a nucleotide base. The high contrasted tumor images of 99mTc-MAVGG-adenine also suggested its potential utility as tumor imaging agent.
Abstract
Two peptide ligands conjugated adenine, [9-N-(tritylmercapto acetyl diglycyl aminoethyl) adenine, Tr-MAG2-Ade] and [9-N-(tritylmercapto acetyl triglycyl aminoethyl) adenine, Tr-MAG3-Ade], are synthesized and labeled with 99mTc by directly labeling method. The stability of 99mTc-MAG2-adenine and 99mTc-MAG3-adenine in vitro is measured. The uptake radios of tumor to muscle at 3h post-injection are 5.70 and 4.92, respectively. The biodistribution and scintigraphic imaging studies show that the two complexes have high localization in tumor and high contrasted tumor images can be obtained, which suggest their potential utility as tumor imaging agents. But the high radioactivity of abdomen could prevent the tumor imaging in this area.
Abstract
As N-2′,4′-dinitrophenyl-3,3-dinitroazetidine (DNPDNAZ) is an important derivative of 3,3-dinitroazetidine, its thermal behavior was studied under 0.1 and 2 MPa by the differential scanning calorimetry (DSC) method. The results of this study show that there are one melting process and two exothermic decomposition processes. Its kinetic parameters of the intense exothermic decomposition process were obtained from the analysis of the DSC curves. The activation energy and the mechanism function under 0.1 MPa are 167.26 kJ mol−1 and f(α) = 3(1 + α)2/3[(1 + α)1/3− 1]−1/2, respectively, and the said parameters under 2 MPa are 169.30 kJ mol−1 and f(α) = 3(1 + α)2/3[(1 + α)1/3− 1]−1/2, respectively. The specific heat capacity of DNPDNAZ was determined using a continuous C p mode of micro-calorimeter. Using the relationship between C p and T with the thermal decomposition parameters, the time of the thermal decomposition from initialization to thermal explosion (adiabatic time-to-explosion, t TIAD), the self-accelerating decomposition temperature (T SADT ), thermal ignition temperature (T TIT), critical temperatures of thermal explosion (T b), and half-life (t 1/2) were obtained to evaluate its thermal safety under different pressures.
Starch is a product of photosynthetic activities in leaves. Wheat yields largely depend on photosynthetic carbon fixation and carbohydrate metabolism in flag leaves. The mapping of quantitative trait loci (QTLs) associated with flag leaf starch content (FLSC) in wheat (Triticum aestivum L.) was completed using unconditional and conditional QTL analyses. The FLSC of this population during the early grain-filling stage was measured at six stages in six environments. Combining unconditional and conditional QTL mapping methods, eight unconditional QTLs and nine conditional QTLs were detected, with five QTLs identified as unconditional and conditional QTLs. Four unconditional QTLs (i.e. qFLS-1B, qFLS-1D-1, qFLS-4A, and qFLS-7D-1) and one conditional QTL (i.e. qFLS-3A-1) were identified in two of six environments. Two QTLs (qFLS-1D-2 and qFLS-7D-1), which significantly affected the FLSC, were identified using the unconditional QTL mapping method, while three QTLs (i.e. qFLS-1A, qFLS-3A-1, and qFLS-7D-1) were detected using the conditional QTL mapping method. Our findings provide new insights into the genetic mechanism and regulatory network underlying the diurnal FLSC in wheat.
Thermodynamic investigation of room temperature ionic liquid
The heat capacity and thermodynamic functions of BMIPF6
Abstract
The molar heat capacities of the room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluoroborate (BMIPF6) 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, C P,m (J K−1 mol−1) = 204.75 + 81.421X − 23.828 X 2 + 12.044X 3 + 2.5442X 4 [X = (T − 132.5)/52.5] for the solid phase (80–185 K), C P,m (J K−1 mol−1) = 368.99 + 2.4199X + 1.0027X 2 + 0.43395X 3 [X = (T − 230)/35] for the glass state (195 − 265 K), and C P,m (J K−1 mol−1) = 415.01 + 21.992X − 0.24656X 2 + 0.57770X 3 [X = (T − 337.5)/52.5] for the liquid phase (285–390 K), respectively. According to the polynomial equations and thermodynamic relationship, the values of thermodynamic function of the BMIPF6 relative to 298.15 K were calculated in temperature range from 80 to 390 K with an interval of 5 K. The glass transition of BMIPF6 was measured to be 190.41 K, the enthalpy and entropy of the glass transition were determined to be ΔH g = 2.853 kJ mol−1 and ΔS g = 14.98 J K−1 mol−1, respectively. The results showed that the milting point of the BMIPF6 is 281.83 K, the enthalpy and entropy of phase transition were calculated to be ΔH m = 20.67 kJ mol−1 and ΔS m = 73.34 J K−1 mol−1.
Abstract
The effects of fullerenes, including fellerene soot (FS), extracted fullerene soot (EFS) and pure C60 on the thermal decomposition of ammonium perchlorate (AP) compared with traditional carbon black (CB) catalyst has been studied by employing thermogravimetry (TG), differential thermal analysis (DTA), infrared spectroscopy (IR) and ignition temperature experiments. The results showed that the addition of CB and FS to AP reduced the activation energy as well as the temperature at maximum decomposition rate, but that of EFS and pure C60 had little effect on the thermal decomposition of AP, and among all catalysts, FS was the best one.
Abstract
3,3-Dinitroazetidinium (DNAZ) salt of perchloric acid (DNAZ·HClO4) was prepared, it was characterized by the elemental analysis, IR, NMR, and a X-ray diffractometer. The thermal behavior and decomposition reaction kinetics of DNAZ·HClO4 were investigated under a non-isothermal condition by DSC and TG/DTG techniques. The results show that the thermal decomposition process of DNAZ·HClO4 has two mass loss stages. The kinetic model function in differential form, the value of apparent activation energy (E a) and pre-exponential factor (A) of the exothermic decomposition reaction of DNAZ·HClO4 are f(α) = (1 − α)−1/2, 156.47 kJ mol−1, and 1015.12 s−1, respectively. The critical temperature of thermal explosion is 188.5 °C. The values of ΔS ≠, ΔH ≠, and ΔG ≠of this reaction are 42.26 J mol−1 K−1, 154.44 kJ mol−1, and 135.42 kJ mol−1, respectively. The specific heat capacity of DNAZ·HClO4 was determined with a continuous C p mode of microcalorimeter. Using the relationship between C p and T and the thermal decomposition parameters, the time of the thermal decomposition from initiation to thermal explosion (adiabatic time-to-explosion) was evaluated as 14.2 s.
Abstract
To investigate the effects of lanthanum exposure on regional distribution of inorganic elements in rat brain. Wistar rats were exposed to lanthanum chloride through oral administration at 0, 0.1, 2, and 40 mg/kg concentration for 6 months. The elements such as Cl, K, Ca, Fe, Cu, and Zn were identified in the brain slices by synchrotron radiation X-ray fluorescence (SRXRF) analysis. Differences of brain elemental distributions were noticed. Cl, Ca, and Zn were primarily concentrated in hippocampus of the controls. With the increase of the lanthanum dosage, the Ca and Zn levels significantly decreased, while the Cu levels significantly elevated in cortex, hippocampus and thalamus. Our results suggest that subchronic lanthanum exposure in rats appears to change elemental distributions in brain.
Abstract
The heat capacities of LiNH2 and Li2MgN2H2 were measured by a modulated differential scanning calorimetry (MDSC) over the temperature range from 223 to 473 K for the first time. The value of heat capacity of LiNH2 is bigger than that of Li2MgN2H2 from 223 to 473 K. The thermodynamic parameters such as enthalpy (H–H 298.15) and entropy (S–S 298.15) versus 298.15 K were calculated based on the above heat capacities. The thermal stabilities of them were investigated by thermogravimetric analysis (TG) at a heating rate of 10 K min−1 with Ar gas flow rate of 30 mL min−1 from room temperature to 1,080 K. TG curves showed that the thermal decomposition of them occurred in two stages. The order of thermal stability of them is: Li2MgN2H2 > LiNH2. The results indicate that addition of Mg increases the thermal stability of Li–N–H system and decrease the value of heat capacities of Li–N–H system.
