Five novel BTF (benzotrifuroxan) cocrystals, possessing a similar density to RDX (1,3,5-trinitrohexahydro-1,3,5-triazine), have been prepared and reported first. Their single-crystal structures are presented and discussed. Interactions between cocrystal formers are discussed with shifts in the IR spectra providing additional support for the presence of various interactions. Hydrogen-bonding and π-stacking interactions are found to be the most prominent. Especially, the interactions between electron-poor π-systems of BTF and electron-rich groups of other cocrystal formers such as nitro groups of TNB exist commonly in all five novel cocrystals. This kind of interaction can be a more potential driving force for energetic cocrystals, since explosives with poor active hydrogen bonds are usually hard to form cocrystals with other explosives for the lack of strong intermolecular interactions. Because of the changes in structure, the physicochemical characteristics including density and melting point together with energetic properties of BTF altered after cocrystallization. All of the densities are between both of the cocrystal formers. Cocrystals of BTF with TNT and TNB have impact sensitivities between those of both cocrystal formers, while the remaining three cocrystals (BTF/TNA, BTF/MATNB, and BTF/TNAZ) all are more sensitive than either cocrystal former. It indicates that a cocrystal with TNT or TNB can reduce the shock sensitivity of BTF; especially, the cocrystal BTF/TNB not only has a lower sensitivity than RDX but also equal energetic properties, which potentially improve the viability of BTF in explosive applications. This paper owns an important consideration in the design of future BTF and other explosive cocrystals, and the result provides some feasibility to improve the application of the high explosive BTF.
Inorganic CsPbI3 perovskites have shown promising potential for achieving all-inorganic photovoltaic (PV) devices. However, the black perovskite polymorph (α-phase) of CsPbI3 easily converts into yellow colour (δ-phase) in an ambient environment and it is only stable at high temperature (above 320 °C), which limits its practical application. Here we tailor the three-dimensional CsPbI3 perovskite into quasi-two-dimension through adding a large radius cation phenylethylammonium (PEA+). The incorporation of PEA+ into the CsPbI3 perovskite significantly improves the film morphology as well as the phase stability. An optimal CsxPEA1-xPbI3 perovskite film remains stable in the α-phase from room temperature to 250 °C in air and yields a power conversion efficiency of 5.7% for its solar device. The concept of using large radius cations in the 3D perovskite system provides a new perspective to further enhance the phase stability while retaining the device performance.
A new occupancy model for predicting the crystal morphologies influenced by solvent and temperature is proposed. In the model, the attachment energy is corrected by a relative occupancy, which is the occupancy of a solute molecule relative to the total ones of a solute molecule and a solvent molecule. The occupancy is defined proportional to the averaged interaction energy between a solute or solvent molecule and a crystal surface. The validity of the model is confirmed by its successful applications to predict the crystal morphologies of a class of well-known nitroamino explosives hexahydro-1,3,5-trinitro-1,3,5-triazine, octahydro-1,3,5,7-tertranitro-1,3,5,7tetrazocine and 2,4,6,8,10,12-hexanitrohexaaz-aisowurtzitane grown in solution. Furthermore, the applications of this model regarding concentration, molecular diffusion ability in solution, and mixed solvents are prospected.
Increasing scientific evidences suggest that aerobic exercise may improve cancer-related fatigue in breast cancer patients, but many existing studies have yielded inconclusive results. This meta-analysis aimed to derive a more precise estimation of the effects of aerobic exercise on cancer-related fatigue in breast cancer patients receiving chemotherapy. The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library, and CBM databases were searched from inception through July 1, 2013 without language restrictions. Crude standardized mean difference (SMD) with 95 % confidence interval (CI) was calculated. Twelve comparative studies were assessed with a total of 1,014 breast cancer patients receiving chemotherapy, including 522 patients in the aerobic exercise group (intervention group) and 492 patients in the usual care group (control group). The meta-analysis results revealed that the Revised Piper Fatigue Scale (RPFS) scores of breast cancer patients in the intervention group were significantly lower than those in the control group (SMD=-0.82, 95% CI=-1.04 ∼ -0.60, P<0.001). However, there was no significant difference in the Functional Assessment of Chronic Illness Treatment-Fatigue scale (FACIT-F) scores between the intervention and control groups (SMD=0.09, 95% CI=-0.07 ∼ 0.25, P=0.224). Subgroup analysis by ethnicity indicated that there were significant differences in RPFS and FACIT-F scores between the intervention and control groups among Asian populations (RPFS: SMD=-1.08, 95% CI=-1.35 ∼ -0.82, P<0.001; FACIT-F: SMD=1.20, 95 % CI=0.70 ∼1.71, P<0.001), but not among Caucasian populations (all P>0.05). The current meta-analysis indicates that aerobic exercise may improve cancer-related fatigue in breast cancer patients receiving chemotherapy, especially among Asian populations.
We report two kinds of evident hydrogen bonded chains constructing two binary cocrystals of 2,4,6,8,10,12hexanitrohexaazaisowurtzitane (CL-20) with para-benzoquinone (1) and 1,4-naphthoquinone (2): one kind is the CL-20 molecule chains linked by R 2 2 (6) hydrogen bonds, and the other is connected by CL-20 and coformer (1 or 2) molecules alternately through R 2 1 (5) hydrogen bonds. All chains extend to the entire cocrystals CL-20/1 and CL-20/2 with crossing points of CL-20 molecules. In contrast to the unremarkable intermolecular interactions in observed CL-20 polymorphs and cocrystals, these two kinds of chains in CL-20/1 and CL-20/2 are evident and can be readily understood using the definition of supramolecular synthons. Moreover, the thermal behaviors, impact sensitivity, and detonation properties of these two energetic cocrystals are reported.
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