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  • Author or Editor: Li Xu x
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Abstract  

The aim of this study was to examine the radioiodinating condition of betulinic acid and understand the possibility of 131I–betulinic acid (131I–BA) as a potential tumor radiotherapy agent through in vitro uptake and in vivo biodistribution studies 131I–BA was prepared by the reaction of betulinic acid with Na131I in the presence of hydrogen peroxide, and then purified by HPLC. The labeling yield was about 80%, and the radiochemical purity was greater than 95%. 131I–BA was found to be stable at 4 °C in saline containing 1% ethanol. In vitro studies showed that 131I–betulinic acid accumulated in the cancer cell lines (BEL-7402 and NCI-H446) in comparison with free 131I. In vivo biodistribution study in KM mice bearing HepA tumor showed that 131I–BA stayed longer time in tumors than free 131I. A significant differences were seen in tumor/muscle ratio at 4 h postinjection between 131I–BA and free 131I. In vivo and in vitro studies showed the higher fraction of 131I–BA can be utilized for therapy and a higher dose will be delivered per targeting event. 131I–BA is a promising radiopharmaceutical in nuclear medicine, especially for hepatocellular tumor targeted radionuclide brachytherapy.

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Abstract  

The paper presents the results of determination of extractable organohalogens (EOX) by instrumental neutron activation analysis (INAA), and polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) by gas chromatography (GC), in atmospheric precipitation in Shanghai, China, from January to August 2005. The results showed that EOCI was the major component of organohalogens in precipitation. A significant correlation between the concentrations of EOBr and EOI was observed (r 2 = 0.75), which suggested that EOBr and EOI in precipitation might mainly come from the same sources. There were no clear seasonal trends for the concentrations of EOX. The concentrations of ΣPCBs ranged from 0.2–2.8 ng/l, with the dominant PCBs containing 3 to 5 chlorine atoms. HCH was the predominant pesticide in precipitation, accounting for over 80% of total OCPs, in which β-HCH took 28%–72% of total HCH. Also, there may be an evidence for significantly historical usage of DDT.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Li Li, Wei Wang, Xiangshang Xu, Hui Wang, Shujie Liao, Wei Li, Weina Zhang, Dan Liu, Bo Cao, Shixuan Wang, Keng Shen and Ding Ma

Abstract  

Radioimmunotherapy (RIT) has emerged as an attractive and promising strategy for the management of malignant diseases. It has been proven to be quite effective in the treatment of numerous tumors, such as non-Hodgkin lymphoma, metastatic prostate cancer, melanoma, thyroid cancer, colon cancer and so on. The RIT currently used is mainly based on monoclonal antibodies to recognize target antigens. As antibodies are large molecules, this method of RIT has some limitations in in vivo use, such as the immunogenicity, the high costs and low efficiency of production. Aptamer is discovered and selected by SELEX technology. As specific recognizers and binders, aptamers and antibodies have such a close similarity as to be interchangeable to some extent. But, aptamers have many advantages over antibodies: higher affinity and specificity, smaller molecular weight, more easily synthesized and modified, more rapidly penetrating into tumors, higher tumor-to-blood distribution ratio and more easily to be cleared. In addition, since aptamer has almost no immunogenicity in vivo, it can be repeatedly administered. Thus, we believe that aptamer-based RIT will be a feasible and promising way to treat human cancers, and it might display better results in cancer treatment than antibody-based RIT. In conclusion, aptamer-based RIT is hopeful to become a key therapeutics in cancer radiotherapy in the near future.

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Abstract

The thermal decomposition behavior of composite modified double-base propellant containing hexanitrohexaazaisowurtzitane (CL-20/CMDB propellant) was studied by microcalorimetry. The kinetic and thermodynamic parameters were obtained from the analysis of the heat flow curves. The effect of different proportion of CL-20 to the thermal decomposition behavior, kinetics, and thermal hazard was investigated at the same time. The critical temperature of thermal explosion (T b), the self acceleration decomposition temperature (T SADT), and the adiabatic decomposition temperature rise (ΔT ad) were calculated to evaluate the thermal hazard of the CL-20/CMDB propellant. It shows that the CMDB propellant with 38% CL-20 has relative lower values of E and lgA, and with 18% CL-20 has the highest potential hazard.

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Journal of Thermal Analysis and Calorimetry
Authors: Li-Fang Song, Cheng-Li Jiao, Chun-Hong Jiang, Jian Zhang, Li-Xian Sun, Fen Xu, Qing-Zhu Jiao, Yong-Heng Xing, F. L. Huang, Yong Du, Zhong Cao, Fen Li and Jijun Zhao

Abstract

One-three-dimensional metal-organic frameworks Mg1.5(C12H6O4)1.5(C3H7NO)2 (MgNDC) has been synthesized solvothermally and characterized by single crystal XRD, powder XRD, FT-IR spectra. The low-temperature molar heat capacities of MgNDC were measured by temperature modulated differential scanning calorimetry (TMDSC) over the temperature range from 205 to 470 K for the first time. No phase transition or thermal anomaly was observed in the experimental temperature range. The thermodynamic parameters of MgNDC such as entropy and enthalpy relative to reference temperature of 298.15 K were derived based on the above molar heat capacities data. Moreover, the thermal stability and decomposition of MgNDC was further investigated through thermogravimetry (TG)–mass spectrometer (MS). Three stages of mass loss were observed in the TG curve. TG–MS curve indicated that the oxidative degradation products of MgNDC are mainly H2O, CO2, NO, and NO2.

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Journal of Thermal Analysis and Calorimetry
Authors: Cheng-Li Jiao, Li-Fang Song, Chun-Hong Jiang, Jian Zhang, Xiao-Liang Si, Shu-Jun Qiu, Shuang Wang, Li-Xian Sun, Fen Xu, Fen Li and Ji-Jun Zhao

Abstract

The low-temperature molar heat capacity of crystalline Mn3(HEDTA)2·10H2O was measured by temperature-modulated differential scanning calorimetry (TMDSC) for the first time. The thermodynamic parameters such as entropy and enthalpy relative to 298.15 K were calculated based on the above molar heat capacity data. The compound was characterized by powder XRD, FT-IR spectrum. Moreover, the thermal decomposition characteristics of Mn3(HEDTA)2·10H2O were investigated by thermogravimetry–mass spectrometer (TG–MS). The experimental result through TG measurement shows that a three-step mass loss process exists. H2O, CO2, NO, and NO2 were observed as products for oxidative degradation of Mn3(HEDTA)2·10H2O from the MS curves.

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Cereal Research Communications
Authors: S.F. Dai, D.Y. Xu, Z.J. Wen, Z.P. Song, H.X. Chen, H.Y Li, J.R. Li, L.Z. Kang and Z.H. Yan

A novel 4.0-kb Fy was sequenced and bacterially expressed. This gene, the largest y-type HMW-GS currently reported, is 4,032-bp long and encodes a mature protein with 1,321 amino acid (AA) residues. The 4.0-kb Fy shows novel modifications in all domains. In the N-terminal, it contains only 67 AA residues, as three short peptides are absent. In the repetitive domain, the undecapeptide RYYPSVTSPQQ is completely lost and the dodecapeptide GSYYPGQTSPQQ is partially absent. A novel motif unit, PGQQ, is present in addition to the two standard motif units PGQGQQ and GYYPTSPQQ. Besides, an extra cysteine residue also occurs in the middle of this domain. The large molecular mass of the 4.0-kb Fy is mainly due to the presence of an extra-long repetitive domain with 1,279 AA residues. The novel 4.0-kb Fy gene is of interest in HMW-GS gene evolution as well as to wheat quality improvement with regard to its longest repetitive domain length and extra cysteines residues.

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Exploring antibiotic resistant mechanism by microcalorimetry

Determination of thermokinetic parameters of metallo-β-lactamase L1 catalyzing penicillin G hydrolysis

Journal of Thermal Analysis and Calorimetry
Authors: Hui-Zhou Gao, Qi Yang, Xiao-Yan Yan, Zhu-Jun Wang, Ji-Li Feng, Xia Yang, Sheng-Li Gao, Lei Feng, Xu Cheng, Chao Jia and Ke-Wu Yang

Abstract

In an effort to probe the reaction of antibiotic hydrolysis catalyzed by B3 metallo-β-lactamase (MβL), the thermodynamic parameters of penicillin G hydrolysis catalyzed by MβL L1 from Stenotrophomonas maltophilia were determined by microcalorimetric method. The values of activation free energy ΔG θ are 88.26, 89.44, 90.49, and 91.57 kJ mol−1 at 293.15, 298.15, 303.15, and 308.15 K, respectively, activation enthalpy ΔH θ is 24.02 kJ mol−1, activation entropy ΔS θ is −219.2511 J mol−1 K−1, apparent activation energy E is 26.5183 kJ mol−1, and the reaction order is 1.0. The thermodynamic parameters reveal that the penicillin G hydrolysis catalyzed by MβL L1 is an exothermic and spontaneous reaction.

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Journal of Thermal Analysis and Calorimetry
Authors: Li-Fang Song, Chun-Hong Jiang, Jian Zhang, Li-Xian Sun, Fen Xu, Yun-Qi Tian, Wan-Sheng You, Zhong Cao, Ling Zhang and Dao-Wu Yang

Abstract  

A novel two-dimensional metal organic framework MgBTC [MgBTC(OCN)2·2H2O, where BTC = 1,3,5-benzenetricarboxylate] has been synthesized solvothermally and characterized by single crystal XRD, powder XRD, FT-IR spectra. The low-temperature molar heat capacities of MgBTC were measured by temperature modulated differential scanning calorimetry (TMDSC) over the temperature range from 190 to 350 K for the first time. No phase transition or thermal anomaly was observed in the experimental temperature range. The thermodynamic parameters of MgBTC such as entropy and enthalpy relative to reference temperature of 298.15 K were derived based on the above molar heat capacities data. Moreover, the thermal stability and decomposition of MgBTC was further investigated through thermogravimetry (TG)-mass spectrometer (MS). Four stages of mass loss were observed in the TG curve. TG-MS curve indicated that the products of oxidative degradation of MgBTC are H2O, N2, CO2 and CO. The powder XRD showed that the mixture after TG contains MgO and graphite.

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Journal of Thermal Analysis and Calorimetry
Authors: Yi-Xi Zhou, Li-Xian Sun, Zhong Cao, Jian Zhang, Fen Xu, Li-Fang Song, Zi-Ming Zhao and Yong-Jin Zou

Abstract

Two metal–organic frameworks (MOFs) of M(HBTC)(4,4′-bipy)·3DMF [M = Ni (for 1) and Co (for 2); H3BTC = 1,3,5-benzenetricarboxylic acid (1,3,5-BTC); 4,4′-bipy = 4,4′-bipyridine; DMF = N,N′-dimethylformamide] were synthesized by a one-pot solution reaction and a solvothermal method, respectively, and characterized by powder X-ray diffraction and FT-IR spectra. The low-temperature molar heat capacities of M(HBTC)(4,4′-bipy)·3DMF were measured by temperature-modulated differential scanning calorimetry (TMDSC) for the first time. The thermodynamic parameters such as entropy and enthalpy relative to reference temperature 298.15 K were derived based on the above molar heat capacity data. Moreover, the thermal stability and the decomposition mechanism of M(HBTC)(4,4′-bipy)·3DMF were investigated by thermogravimetry analysis (TGA). The experimental results through TGA measurement demonstrate that both of the two compounds have a three-stage mass loss in air flow.

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