High Entropy Alloys as Filler Metals for Joining

In the search for applications for alloys developed under the philosophy of the High Entropy Alloy (HEA)-type materials, the focus may be placed on applications where current alloys also use multiple components, albeit at lower levels than those found in HEAs. One such area, where alloys with complex compositions are already found, is in filler metals used for joining. In soldering (<450 °C) and brazing (>450 °C), filler metal alloys are taken above their liquidus temperature and used to form a metallic bond between two components, which remain both unmelted and largely unchanged throughout the process. These joining methods are widely used in applications from electronics to aerospace and energy, and filler metals are highly diverse, to allow compatibility with a broad range of base materials (including the capability to join ceramics to metals) and a large range of processing temperatures. Here, we review recent developments in filler metals relevant to High Entropy materials, and argue that such alloys merit further exploration to help overcome a number of current challenges that need to be solved for filler metal-based joining methods.     

Quantum Breathers in a Two-Dimensional Hexangular Heisenberg Ferromagnet

International Journal of Theoretical Physics - We present a theoretical study on quantum breathers in a XXZ Heisenberg ferromagnet with the single-ion uniaxial anisotropy on a two-dimensional...     

An Ultrasensitive Virus ELISA Based on a magnetic Mesoporous Silica Nanoprobe

Detection of infectious viruses relies on quantitative polymerase chain reaction (qPCR). However, qPCR requires costly equipment, a clean operating environment and experienced technicians, limiting its wide applicability. On the other hand, enzyme-linked immunosorbent assay (ELISA) is widely used in biological laboratories due to its relatively high sensitivity and ease of operation. However, ELISA-based detection of the virus is hampered because it is lower sensitive than qPCR. Herein, a nanoprobe ELISA (NP-ELISA) based on a mesoporous silica nanoprobe, which is constructed by first being loaded with peroxidase and further coated with positively charged polymer polyethyleneimine, and finally functionalized with antivirus antibodies, is designed. Results show that each NP probe is encapsulating 170 peroxidase molecules and presents 200 antibody molecules on the surface. The limit of detection (LOD) of NP-ELISA (LOD = 1450 PFU mL⁻¹) for the detection of real virus samples is tenfold sensitive than that of standard ELISA (LOD = 14, 414 PFU mL⁻¹) and the assay time for NP-ELISA is reduced by 1 h as compared with standard one. Therefore, the NP-ELISA provides a rapid and sensitive immunoassay platform that can readily be implemented for biological laboratory research as well as for on-site clinical diagnostics.     

LaAlO_3/SrTiO_3界面增强光伏效应

探索LaAlO_3/SrTiO_3(LAO/STO)界面产生的新奇物理特性对理解关联电子系统中多自由度耦合和设计功能材料器件具有重要的价值.本文通过脉冲激光沉积方法在SrTiO_3基底上制备了LAO/STO薄膜,研究了正面照射LAO/STO膜面和侧面照射LAO/STO界面时的光伏效应,探讨了LAO/STO界面对光伏效应的影响.研究结果表明,在同样光照能量下侧面照射LAO/STO界面产生的光电压远高于正面照射LAO/STO膜面产生的光电压,说明LAO/STO界面对光伏效应有明显的增强作用.通过偏压调控可以进一步增强照射LAO/STO界面产生的光电压,当偏压为60 V时, LAO/STO样品的位置探测灵敏度达到了36.8 mV/mm.这些研究结果为设计场调控位置敏感探测器等新型光电子器件提供了新的思路.     

气体团簇离子束两步能量修形法的平坦化效应

本文提出采用气体团簇离子束的两步能量修形法来改善4H-SiC(1000)晶片表面形貌.先用15 keV的高能Ar团簇离子进行整体修形,再用5 keV的低能团簇离子优化表面.结果表明,在相同的团簇离子剂量下,与单一15 keV的高能团簇处理相比,两步法修形后的表面具有更低的均方根粗糙度,两者分别为1.05 nm和0.78 nm.本文还以原子级平坦表面为研究对象,揭示了载能团簇引起的半球形离子损伤(弧坑)与团簇能量的关系,及两步能量修形法在弧坑修复中的优势.在原子力显微镜表征的基础上,引入了二维功率谱密度函数,以直观全面地给出材料的表面形貌特征及其随波长(频率)的分布.结果表明,经任何能量的团簇离子轰击的表面,在0.05—0.20μm波长范围内,团簇轰击都能有效地降低粗糙度,而在0.02—0.05μm范围内,则出现了粗化效应,这是由于形成了半球形离子损伤,但第二步更低能量的团簇离子处理可以削弱这种粗化效应.     

Site-selective Csp3-H aryloxylation of natural product Tanshinone IIA and its analogues

A novel catalyst-free Csp³-H aryloxylation approach allowing for rapid installation of a wide range of aryloxyl groups regioselectively at the C-4 position of Tanshinone IIA under simple and mild conditions was developed. This unique protocol exhibited atom-/step-economy, low cost, high efficiency and robust functional-group tolerance, which will greatly facilitate to diversify the A-ring of the bioactive natural product.     

Bi(IO3)F2: The First Metal Iodate Fluoride with a Very Strong Second Harmonic Generation Effect

The first metal iodate fluoride, Bi(IO₃)F₂, with a strong second harmonic generation (SHG) effect has been prepared. Bi(IO₃)F₂ crystallizes in the polar space group C2 and features a three‐dimensional [BiF₂]⁺ cationic framework with IO₃ groups capping the inner walls of the one‐dimensional tunnels. This [BiF₂]⁺ cationic framework acts as a template for the assembly of the polar IO₃ units in a favorable superposed fashion, which leads to the polar structure of the material. Bi(IO₃)F₂ displays a rather wide transmittance window (0.3–11 μm) and exhibits a very strong SHG response that is about 11.5 times larger than that of KH₂PO₄ (KDP) under 1064 nm laser radiation and the same as that of KTiOPO₄ (KTP) under 2.05 μm laser radiation. Preliminary investigations indicate that Bi(IO₃)F₂ is a promising nonlinear optical material in the visible and mid‐IR region.     

Enantioselective Synthesis of (+)-Mitomycin K by a Palladium-Catalyzed Oxidative Tandem Cyclization

The mitomycins, a family of bioactive natural products, feature a compact 6/5/5-fused polycyclic ring structure densely decorated with highly reactive and/or fragile quinone, amino ketal, and aziridine as well as carbamate moieties. It is this striking feature that has defeated numerous synthetic attempts towards these apparently small molecules, rendering them one of the most formidable targets for total synthesis. We herein report the first enantioselective synthesis of (+)-mitomycin K, a representative of G series mitomycins. The key step of this synthesis is an enantioselective oxidative cyclization catalyzed by a palladium/(+)-sparteine system that had previously been developed by our group. The robustness of this method bodes well for further applications in the asymmetric total synthesis of natural products, particularly those with characteristic 6/5/5-fused pyrroloindole skeletons.     

Measurement of mineral solubilities in the ternary systems NaCl−ZnCl<Subscript>2</Subscript>−H<Subscript>2</Subscript>O and MgCl<Subscript>2</Subscript>−ZnCl<Subscript>2</Subscript>−H<Subscript>2</Subscript>O at 373 K

In this work, the solubilities of the salt minerals and the densities of solution in two ternary systems sodium chloride–zinc chloride–water and magnesium chloride–zinc chloride–water were measured at 373 K using an isothermal solution saturation method. Based on the determined equilibrium solubility data and the corresponding equilibrium solid phase, the phase diagrams and density diagrams of the two systems were plotted. The results show that the two ternary systems are complex and the eutectic points, the univariant solubility curves and the solid crystalline phase regions are shown and discussed. The phase diagram of the ternary system NaCl?ZnCl₂?H₂O at 373 K is constituted of two eutectic points, three univariant solubility curves and three solid crystalline phase regions corresponding to NaCl, ZnCl₂ and 2NaCl · ZnCl₂. And the phase diagram of the ternary system MgCl₂?ZnCl₂?H₂O at 373 K includes two eutectic points, three univariant solubility curves and three solid crystalline phase regions corresponding to MgCl₂ · 6H₂O, MgCl₂ · ZnCl₂ · 5H₂O and ZnCl₂. The experimental results were simply discussed.     

Synthesis and effect on SMMC-7721 cells of new benzo[c,d]indole rhodanine complex merocyanines as PDT photosensitizers

Photodynamic therapy (PDT) represents a modern and noninvasive therapeutic approach, however, it relies on the development of photosensitizers. Here five new benzo[c,d]indole rhodamine complex merocyanines (BIRCM) D1-D5, displaying low dark toxicity and significant photo toxicity, were synthesized as PDT photosensitizers, and characterized by ¹H NMR, IR, UV–Vis and HRMS. The investigation of their absorption spectra in different solvents showed that the absorption maxima and molar extinction coefficient were in the region 507–679 nm and 0.21 × 10⁴–1.27 × 10⁵ L · mol^?1cm^?1, respectively. The evaluation of PDT activity showed that only irradiation could not kill SMMC-7721 cells, and the cell survival rate and inhibition rate at the application dose and duration was 92%–87% and 78%–49%, respectively. Especially, using D2, absorbed in the red zone, as photosensitizer for PDT analyzed its effect on SMMC-7721 cells survival, it could be found that the cell survival rate was 92% without irradiating and the cell inhibited rate was 78% under irradiating at concentrations of 2.5 × 10^?6 mol/L, displaying low dark toxicity and high photo toxicity, which was valuable for PDT of some microvascular diseases or other superficial diseases.