Stochastic chemo-physical-mechanical degradation analysis on hydrated cement under acidic environments

The accumulation of material degradation under contact with aggressive aqueous environments could lead to reduced structural reliability. In terms of hydrated cementitious materials, such interactions often result in the chemo-physical-mechanical (CPM) degradation, which represents a multiphysics process of high non-linearity and complexity. By further considering the inevitable uncertainties associated with both the materials and the serving conditions, solving such a process requires novel probabilistic approaches. This paper presents a stochastic chemo-physical-mechanical (SCPM) degradation analysis on the hydrated cement under acidic environment. The SCPM analysis consists of modelling the stochastic chemophysical degradation by finite element method, and assessing the mechanical deterioration through analytical micromechanics. The proposed modelling framework couples the conventional Monte Carlo Simulation with a novel support vector regression algorithm. The present method is able to not only address the detailed degradation mechanisms, but also ensure low computational costs for an accurate SCPM degradation assessment.     

Simultaneous Removal of Antibiotics and Heavy Metals with Poly(Aspartic Acid)-Based Fenton Micromotors

The discharge of diverse pollutants has led to a complex water environment and posed a huge health threat to humans and animals. Self-propelled micromotors have recently attracted considerable attention for efficient water remediation due to their strong localized mass transfer effect. However, a single functionalized component is difficult to tackle with multiple contaminants and requires to combine different decontamination effects together. Here, we introduced a multifunctional micromotor to implement the adsorption and degradation roles simultaneously by integrating the poly(aspartic acid) (PASP) adsorbent with a MnO₂-based catalyst. The as-prepared micromotors are well propelled in contaminated waters by MnO₂ catalyzing hydrogen peroxide. In addition, the catalytic ramsdellite MnO₂(R-MnO₂) inner layer is decorated with Fe₂O₃ nanoparticles to improve their catalytic performance, contributing to an excellent degradation ability with 90% tetracycline (TC) removal in 50 minutes by enhanced Fenton-like reactions. Combining the attractive adsorption capability of poly (aspartic acid) (PASP), the composite micromotors offer an efficient removal of heavy metal ions in short time. Moreover, the designed micromotors are able to simultaneously remove antibiotic and heavy metals in mixed contaminants circumstance just in single treatment. This multifunctional micromotor with distinctive decontamination ability exhibits a promising prospective in treating multiple pollutants in the future.     

Photo-Controlled Macroscopic Self-Assembly Based on Photo-Switchable Hetero-Complementary Quadruple Hydrogen Bonds

A photo-switchable hetero-complementary quadruple H-bonding array, which consists of an azobenzene-derived ureidopyrimidinone (UPy) module ( Azo-UPy ) and a nonphotoactive diamidonaphthyridine (DAN) derivative ( Napy-1 ), is constructed based on a reversible photo-locking approach. Upon UV (390 nm)/Vis (460 nm) light irradiations, photo-switchable quadruple H-bonded dimerization between Azo-UPy and Napy-1 can be achieved with exhibiting 4.8×10⁴-fold differences in binding strength (ON/OFF ratios). Furthermore, smart polymeric gels with unique photo-controlled macroscopic self-assembly behavior can be fabricated by introducing such quadruple H-bonding array as photo-regulable noncovalent interfacial connections.     

New catalytic effect of thiourea on the oxidative cyanation of N-aryltetrahydroisoquinolines

Thiourea itself has been introduced as a mild and efficient organocatalyst for the oxidative α -cyanation of N-aryltetrahydroisoquinolines (THIQs) with trimethylsilyl cyanide (TMSCN), giving the corresponding products in good to excellent yields. Experimental investigations demonstrated that thiourea acts as a radical initiator by abstracting hydroxyl radical (OH) from tert-butyl hydroperoxide (TBHP) directly instead of non-covalent hydrogen bondings (H-bondings) activation. The use of thiourea as a radical initiator offers a new avenue for innovative chemical transformations in organocatalyzed radical chemistry.     

Cecropin B抗菌肽接枝丝素蛋白膜的制备和表征

以体积分数为60%的乙醇处理制得不溶性再生丝素膜, 通过碳二亚胺法将Cecropin B抗菌肽共价接枝到丝素膜表面, 利用红外光谱、扫描电镜、X射线能谱和抗菌性测试等手段对制得的丝素膜结构和表面特性及其抗菌性能进行了测试分析. 结果表明, Cecropin B抗菌肽成功地接枝到了丝素膜的表面, 接枝后的丝素膜水溶性低, 并具有良好、 持久的抗菌能力.     

Towards the synthesis of insulated oligoynes: A ring-closing-metathesis approach to molecular encapsulation

Masked hexayne 18 was prepared in 11 steps from commercially available reagents. The four butenyl substituents contained within the two arylsilane residues in 18 have been used in a double ring-closing-metathesis operation in an attempt to encapsulate the π-conjugated framework. When 18 was treated with Grubbs’ 1st generation metathesis catalyst however, double ring-closing metathesis provided macrocycle 19 as the major product in good yield. Reasons why the macrocycle in 19 crowns, rather than encapsulates, the π-conjugated framework are discussed.     

桑蚕丝素蛋白初始结构对其矿化作用的影响

以碱金属离子诱导桑蚕丝素蛋白溶液发生构象转变, 研究了蛋白质初始结构对其矿化作用的影响. FT-IR, XRD和SEM等测试结果显示, 未经任何处理的桑蚕丝素蛋白溶液矿化后形成片状复合物, 其无机相以二水磷酸氢钙(DCPD)为主; 而经过K^＋和Na^＋金属离子处理后, 桑蚕丝素溶液的结构由无规线团/螺旋构象向β-折叠发生转变, 矿化后成纤维状, 并相互结合呈现纳米级的三维多孔结构, 其无机相以热力学稳定的羟基磷灰石(HA)为主. 可以认为, 丝素蛋白结构转化为较伸展的β-折叠后, 使得更多的亲水基团暴露在外面, 在丝素蛋白分子不断凝聚成纤过程中, HA结晶快速生长并附着在这些微纤上, 最终形成纤维状的丝素蛋白/HA复合物. 该结果为阐明蛋白质的生物矿化过程及其调控机理提供了理论依据, 同时可以从矿化复合物的形成来反映这些微量元素可能对骨组织形成的影响, 为临床骨组织的修复提供一定的参考.     

A convenient method for the preparation of oxazaborolidine catalyst in situ using (S)-α,α-diphenylpyrrolidinemethanol,tetrabutylammonium borohydride,and methyl iodide for the asymmetric reduction of prochiral ketones

An oxazaborolidine catalyst is readily prepared in situ at 25 °C in THF using (S)-α,α-diphenylpyrrolidinemethanol and borane generated from tetrabutylammonium borohydride/CH₃I reagent system. The oxazaborolidine/BH₃ reagent system prepared in this way is useful for the reduction of prochiral ketones to the corresponding alcohols with up to 99% ee.     

离子液体支载稀土催化剂催化 2,2-二甲基-三亚甲基碳酸酯均聚及其与ε-己内酯的共聚

首次合成了离子液体支载稀土催化剂,并探讨了其催化2,2-二甲基-三亚甲基碳酸酯(DTC)均聚及其与ε-己内酯(ε-CL)的共聚,结果表明该新型催化剂能有效地催化DTC的均聚及其与ε-CL的共聚.研究了不同稀土以及加料顺序等反应条件对聚合的影响,发现轻稀土的催化活性比重稀土高,其中离子液体支载La催化剂的催化活性最高,而通过控制不同的加料顺序可以制备DTC和ε-CL的无规及嵌段共聚物.对共聚物结构进行了表征.