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Pin Liu Xiongmin Liu Tei Saburi Shiro Kubota Pinxian Huang Yuji Wada 《RSC advances》2021,11(33):20529
Turpentine is a renewable resource, has good combustion performance, and is considered to be a fuel or promising additive to diesel fuel. This is very important for the investigation of thermal stability and energy oxidation characteristics, because evaluation of energy or fuel quality assurance and use safety are necessary. The main components of turpentine are α-pinene and β-pinene, which have unsaturated double bonds and high chemical activity. By investigating their thermal stability and oxidation reaction characteristics, we know the chemical thermal properties and thermal explosion hazard of turpentine. In this present study, the thermal stability and oxidation characteristics of α-pinene, β-pinene and α-pinene/β-pinene mixture were investigated using a high sensitivity accelerating rate calorimeter (ARC) and C80 calorimeter. The important parameters of oxidation reaction and thermal stability were obtained from the temperature, pressure and exothermic behavior in chemical reaction. The results show that α-pinene and β-pinene are thermally stable without chemical reaction under a nitrogen atmosphere even when the temperature reaches 473 K. The initial exothermic temperature of the two pinenes and their mixture is 333–338 K, and the heat release (−ΔH) of their oxidation is 2745–2973 J g−1. The oxidation activation energy (Ea) of α-pinene, β-pinene and α-pinene/β-pinene mixture is 116.25 kJ mol−1, 121.85 kJ mol−1, and 115.95 kJ mol−1, respectively. There are three steps in the oxidation of pinenes: the first is the induction period of the oxidation reaction; the second is the main oxidation stage, and the pressure is reduced; the third is thermal decomposition to produce gas.Turpentine is a renewable resource, has good combustion performance, and is considered to be a fuel or promising additive to diesel fuel. 相似文献
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T Cell Receptor–γ/δ Cells Protect Mice from Herpes Simplex Virus Type 1–induced Lethal Encephalitis
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Roger Sciammas P. Kodukula Q. Tang R.L. Hendricks J.A. Bluestone 《The Journal of experimental medicine》1997,185(11):1969-1975
Increased numbers of T cell receptor (TCR)-γ/δ cells have been observed in animal models of influenza and sendai virus infections, as well as in patients infected with human immunodeficiency virus and herpes simplex virus type 1 (HSV-1). However, a direct role for TCR-γ/δ cells in protective immunity for pathogenic viral infection has not been demonstrated. To define the role of TCR-γ/δ cells in anti–HSV-1 immunity, TCR-α−/− mice treated with anti– TCR-γ/δ monoclonal antibodies or TCR-γ/δ × TCR-α/β double-deficient mice were infected with HSV-1 by footpad or ocular routes of infection. In both models of HSV-1 infection, TCR-γ/δ cells limited severe HSV-1–induced epithelial lesions and greatly reduced mortality by preventing the development of lethal viral encephalitis. The observed protection resulted from TCR-γ/δ cell–mediated arrest of both viral replication and neurovirulence. The demonstration that TCR-γ/δ cells play an important protective role in murine HSV-1 infections supports their potential contribution to the immune responses in human HSV-1 infection. Thus, this study demonstrates that TCR-γ/δ cells may play an important regulatory role in human HSV-1 infections. 相似文献
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Shoufeng Wang Shuya Xing Yingying Zhang Yafei Fan Huaiqing Zhao Jianfeng Wang Shuxiang Zhang Wengui Wang 《RSC advances》2019,9(71):41847
We herein report the functionalization of α-C–H in alcohols through cross-dehydrogenative coupling reactions. Selectfluor was used as a mild oxidant. In situ-generated HF participated in the reaction and no external strong acid was necessary. A variety of heteroaryl-substituted alcohols were achieved with good yields and with good functional group tolerance.We herein report the functionalization of α-C–H in alcohols through cross-dehydrogenative coupling reactions.Alcohols are one of the most important types of compounds, because they exist universally in bioactive molecules and are also found in nature in the form of sugars, steroids, etc. Furthermore, alcohols can be used as versatile building blocks, and be transformed into other functional groups. The synthesis of alcohols is a classic topic in organic chemistry. Late-stage functionalization has attracted the interest of chemists because in this way complex molecules could be modified. In particular, functionalization of C–H is a very efficient way to build various structures, as pre-functionalization here is not needed. Thus, transformation of C–H in alcohols is a direct method to prepare diverse alcohols from simple molecules.During the past several decades, activations of the α sp3 C–H groups of alcohols have been achieved through radical-involved processes. In the early research, functionalizations of α C–H groups in alcohols were always initiated by light or di-tert-butyl peroxide, and the generated radicals could add to alkenes, affording alkylated alcohols.1 This reaction was developed by Duan to construct hydroxyl-containing oxindoles through a tandem addition/cyclization reaction.2 Also, amino alcohols were prepared through addition of radicals generated from alcohols to unactivated alkenes.3 Reactions catalyzed by metals such as Rh,4 Fe,5 Cu and Co6 have also been applied. In 2009, addition of such radicals to alkynes was reported. Homoallylic alcohols were prepared using simple alcohol molecules.7 The reactions of alcohols and cinnamic acids were also reported and allylic alcohols were obtained.8 However, arylations of the α C–H in alcohols have attracted much interest because such structures are present in many bioactive molecules (Fig. 1). Great efforts have been expended to the synthesis of arylated alcohols. In 2014, Liu reported the reaction of alcohol molecules and isocyanide, and various alkyl-substituted phenanthridines were achieved.9Open in a separate windowFig. 1Bioactive molecules containing alcoholic hydroxyl groups.Cross-dehydrogenative coupling reactions have been the focus of many researchers and have been shown to be powerful and convenient tools in organic synthesis.10 The activation of the C–H groups in two molecules allows application of starting materials without further functionalization. This simple process with high atomic economy provides an ideal transformation for the preparation of various target compounds. The Minisci reaction has been widely explored since the 1960s. Palmer and McIntyre first reported the hydroxymethylation of quinolone in the presence of hydroxylamine-O-sulphonic acid (HSA).11 Minisci further developed an Fe-catalyzed process that resulted in good yields.12 PdCl2 (ref. 13) and TiCl3 (ref. 14) were also shown to be efficient catalysts for the Minisci reaction. Metal-free reactions initiated by TBHP15 and M2S2O8 (M = Na, K, NH4)16 have also been developed. Very recently, as visible light-promoted processes find applications in organic synthesis, visible light-induced Minisci reactions have been reported.17 However, a strong oxidant, external acid, and complex system are always needed for these reactions. In our research, we found that Selectfluor could be used as a mild oxidant for the functionalizations of C–H groups in ethers, and the HF generated in situ could be made to participate in the reaction process.18 Herein, we report an Ag/Selectfluor-catalyzed Minisci reaction, in which Selectfluor was used as a mild oxidant and no external acid was necessary (Scheme 1).Open in a separate windowScheme 1Arylations of α sp3 C–H groups in alcohols.We chose quinaldine as the model substrate and carried out the reactions ( Entry AgNO3 (eq.) Selectfluor (eq.) Time (h) MeOH : H2Ob Yieldc (%) 1 0.5 0.25 4 3 : 1 Trace 2 0.5 0.5 4 3 : 1 7 3 0.5 1 4 3 : 1 24 4 0.5 4 4 3 : 1 76 5 1 4 4 3 : 1 88 6 2 4 4 3 : 1 89 7 1 4 4 1 : 1 88 8 1 4 4 9 : 1 96 9 1 4 2 9 : 1 93 10 1 4 6 9 : 1 93 11d 1 4 4 9 : 1 90 12e 1 4 4 9 : 1 85