坚硬顶板爆破切顶在沿空留巷中的应用研究

当煤层上方为坚硬顶板时,在工作面回采期间容易出现大面积悬顶,导致巷旁充填体出现大变形破坏,极大威胁采煤安全.为解决这一问题,以某矿1205工作面沿空留巷为工程背景,分析了爆炸围岩裂隙范围和坚硬顶板破断特征,建立了切顶卸压围岩结构力学模型,研究表明,相邻炮孔爆炸后,炮孔间裂隙互相贯穿,降低了顶板强度,同时当切顶角为15°时,巷道稳定性较好.工程实践结果表明:采用爆破切顶技术后,顶板下沉量减小了62.3%,较好地保证了围岩稳定性.     

基于XPS对硫铁矿去除SeO2-3的机理研究

硒是动植物及人体生长必需的十五种微量元素之一，具有清除体内自由基、抗氧化、增强免疫力等功能，但其安全剂量的范围却很窄。利用扫描电子显微镜（SEM）和X射线衍射仪（XRD）对湿法球磨制备的硫铁矿形貌进行了表征。SEM观测发现加乙醇助磨后的硫铁矿为粒径大小较均匀的球形颗粒团聚体，粒径范围在17～200 nm之间，平均粒径138 nm。XRD衍射图谱中的特征峰与FeS₂衍射图谱中各峰位置基本一致，因此判定硫铁矿中主要化学组分为FeS₂，且图谱中基本没有杂峰，表明制备过程中并未混入杂质，样品纯度较高。实验结果表明，该法制备的硫铁矿具有颗粒粒径小、比表面积大、反应活性高等优点。研究中利用X射线光电子能谱仪（XPS）对硫铁矿去除水体中SeO2-₃的机理进行了研究。研究结果表明, （1）在较为广泛的实验pH范围（pH 2.2～11.5），硫铁矿均能有效去除水体中SeO2-₃，去除效率（除pH值7.8以外）均达到90%以上；（2）硫铁矿与SeO2-₃发生反应后，其主要组成元素的XPS特征峰结合能有所减小，表明硫铁矿表面发生了一定化学变化；（3）酸碱环境下硫铁矿去除SeO2-₃的机理不完全相同，酸性环境下，硫铁矿对SeO2-₃的去除是单纯的氧化还原过程，即硫铁矿中被酸活化的S2-₂将SeO2-₃还原为单质Se(0)，并且酸性越强，SeO2-₃去除效果越好；碱性环境下，SeO2-₃的去除过程中氧化还原与络合反应并存，硫铁矿表面有络合态Fe(OH)SeO₃和单质Se(0)两种存在形态，且碱性越强，络合态Fe(OH)SeO₃含量越高。以上研究结果为硫铁矿去除固定水体和土壤中以SeO2-₃为代表的可变价金属阴离子提供重要理论依据和应用基础。     

Flow-induced shear stress and deformation of a core–shell-structured microcapsule in a microchannel

A numerical model was developed and validated to investigate the fluid–structure interactions between fully developed pipe flow and core–shell-structured microcapsule in a microchannel. Different flow rates and microcapsule shell thicknesses were considered. A sixth-order rotational symmetric distribution of von Mises stress over the microcapsule shell can be observed on the microcapsule with a thinner shell configuration, especially at higher flow rate conditions. It is also observed that when being carried along in a fully developed pipe flow, the microcapsule with a thinner shell tends to accumulate stress at a higher rate compared to that with a thicker shell. In general, for the same microcapsule configuration, higher flow velocity would induce a higher stress level over the microcapsule shell. The deformation gradient was used to capture the microcapsule's deformation in the present study. The effect of Young's modulus on the microcapsule shell on the microcapsule deformation was investigated as well. Our findings will shed light on the understanding of the stability of core–shell-structured microcapsule when subjected to flow-induced shear stress in a microfluidic system, enabling a more exquisite control over the breakup dynamics of drug-loaded microcapsule for biomedical applications.     

Characterization of diterpene metabolism in rats with ingestion of seed products from Euphorbia lathyris L. (Semen Euphorbiae and Semen Euphorbiae Pulveratum) using UHPLC-Q-Exactive MS

Previous pharmacological studies have indicated that diterpenoids are the primary effective chemical cluster in the seeds of Euphorbia lathyris L. The seed products are used in traditional Chinese medicine in the forms of Semen Euphorbiae (SE) and Semen Euphorbiae Pulveratum (SEP). However, the metabolism of the plant's diterpenoids has not been well elucidated, which means that the in vivo metabolite products have not been identified. The current study screened the physiological metabolites of six diterpenes [Euphorbia factor L₁ (L1), L₂ (L2), L₃ (L3), L_7a (L7a), L_7b (L7b), and L₈ (L8)] in feces and urine of rats after oral administration of SE and SEP using UHPLC-Q-Exactive MS. A total of 22 metabolites were detected in feces and 8 in urine, indicating that the major elimination route of diterpenoids is via the colon. Hydrolysis, methylation, and glucuronidation served as the primary metabolic pathways of these diterpenoids. In sum, this study contributed to the elucidation of new metabolites and metabolic pathways of SE and SEP, and the new chemical identities can be used to guide further pharmacokinetic studies.     

Bicomponent Cocatalyst Decoration on Flux-assisted CaTaO2N Single Crystals for Photocatalytic CO2 Reduction under Visible Light

Cubic-like CaTaO₂N photocatalysts with high crystallinity and uniform particle size were successfully prepared by the flux-assisted nitridation method. The growth of CaTaO₂N single crystals under different synthesis conditions was systematically investigated to understand the effects of the crystallinity and optical property on photocatalytic performance of CO₂ reduction. Moreover, the modification of CaTaO₂N single crystals with core-shell Ni−Ag bicomponent cocatalyst by two-step decoration process gave a 2.4 times higher amount of CO evolution than the deposition of sole Ag cocatalyst, because of the synergistic effects of bicomponent cocatalyst on the interfacial electron transfer and surface catalytic process. This study provides a valuable way to construct high-crystalline photocatalysts with effective bicomponent cocatalyst for visible-light-driven CO₂ reduction with H₂O.     

Synthesis of molybdenum disulfide/graphene oxide composites for effective removal of U (VI) from aqueous solutions

Journal of Radioanalytical and Nuclear Chemistry - In this study, a novel adsorbents, molybdenum disulfide-graphene oxide (MoS2–GO) composites, is prepared by one-step hydrothermal method and...     

In vitro and in vivo evaluation of a novel anti-EGFR antibody labeled with 89Zr and 177Lu

Journal of Radioanalytical and Nuclear Chemistry - There is an urgent need to develop more specific targeted therapies for lung cancer treatment due to the its low survival rate. EGFR is a...     

Developing the Low-Temperature Oxidation Mechanism of Cyclopentane: An Experimental and Theoretical Study

At present, the reactivity of cyclic alkanes is estimated by comparison with acyclic hydrocarbons. Due to the difference in the structure of cycloalkanes and acycloalkanes, the thermodynamic data obtained by analogy are not applicable. In this study, a molecular beam sampling vacuum ultraviolet photoionization time-of-flight mass spectrometer (MB-VUV-PI-TOFMS) was applied to study the low-temperature oxidation of cyclopentane (CPT) at a total pressure range from 1–3 atm and low-temperature range between 500 and 800 K. Low-temperature reaction products including cyclic olefins, cyclic ethers, and highly oxygenated intermediates (e. g., ketohydroperoxide KHP, keto-dihydroperoxide KDHP, olefinic hydroperoxides OHP and ketone structure products) were observed. Further investigation of the oxidation of CPT – electronic structure calculations – were carried out at the UCCSD(T)-F12a/aug-cc-pVDZ//B3LYP/6-31+ G(d,p) level to explore the reactivity of O₂ molecules adding sequentially to cyclopentyl radicals. Experimental and theoretical observations showed that the dominant product channel in the reaction of CPT radicals with O₂ is HO₂ elimination yielding cyclopentene. The pathways of second and third O₂ addition – the dissociation of hydroperoxide – were further confirmed. The results of this study will develop the low-temperature oxidation mechanism of CPT, which can be used for future research on accurately simulating the combustion process of CPT.