Spark plasma and microwave sintering of Al6061 and Al2124 alloys

Despite the importance of aluminum alloys as candidate materials for applications in aerospace and automotive industries, very little work has been published on spark plasma and microwave processing of aluminum alloys. In the present work, the possibility was explored to process A12124 and A16061 alloys by spark plasma and microwave sintering techniques, and the microstructures and properties were compared. The alloys were sintered for 20 rain at 400, 450, and 500℃. It is found that compared to microwave sintering, spark plasma sintering is an effective way to obtain homogenous, dense, and hard alloys. Fully dense （100%） A16061 and A12124 alloys were obtained by spark plasma sintering for 20 rain at 450 and 500℃, respectively. Maximum relative densities were achieved for A16061 （92.52%） and A12124 （93.52%） alloys by microwave sintering at 500℃for 20 min. The Vickers microhardness of spark plasma sintered samples increases with the increase of sintering temperature from 400 to 500℃, and reaches the values of Hv 70.16 and Hv 117.10 for A16061 and A12124 alloys, respectively. For microwave siutered samples, the microhardness increases with the increase of sintering temperature from 400 to 450℃, and then decreases with the further increase of sintering temperature to 500~C.

Synthesis, Characterization and Antibacterial Activities of Polydentate Schiff Bases, Based on Salicylaldehyde

Three Schiff bases L1, L2 and L3 were synthesized by condensing salicylaldehyde with 4-aminoantipyrine, ethylendiamine and 2-aminophenol respectively and subsequently characterized by various physicochemical investigations. All the three compounds were screened for their In-vitro antibacterial activity against two gram positive bacteria, Staphylococcus aureus (S.A), Staphylococcus epidermidis (S.E) and two gram negative bacteria Klebsiella pneumoniae (K.P) and Pseudomonas aeruginosa (P.A) by agar diffusion method. On comparing the results obtained with the activity of commercially available antibiotics such as Ciprofloxacin and Chloramphenicol, the newly synthesized compounds showed comparable antibacterial activities. The solvent methanol exhibit activity against all bacterial species with IZs ranging from 8 ± 0.25 to 17 ± 0.29 mm while the standard antibiotics Ciprofloxacin and Chloramphenicol exhibited an activities with IZs varying from 21.3 ± 0.31 to 28.3 ± 0.32 and 26.3 ± 0.24 mm to 32.3 ± 0.23 mm, respectively. However, the newly synthesized Schiff bases L1, L2 and L3 showed IZs ranging from 7.4 ± 0.23 to 32.5 ± 0.14, 3 ± 0.57 to 12 ± 0.28 and 10 ± 0.20 to 32 ± 0.36 respectively. Among the Schiff bases, L3 showed the activity (32 ± 0.36) against S.E and P.A which is higher than the activity of standard antibiotics Ciprofloxacin and Chloramphenicol against the same bacterial strains. The results obtained revealed that all the synthesized Schiff bases exhibit appreciable antibacterial activity against all the bacteria species which potentially makes them, to apply as wide range antibacterial drugs, after further in-vivo cytotoxicity investigations. Their activity can also be further modified by changing the functionality of precursors for Schiff base condensation.

Development of calcium stabilized nitrogen rich α-sialon ceramics along the Si_(3)N_(4):1/2Ca_(3)N_(2):3AlN line using spark plasma sintering

Calcium stabilized nitrogen rich sialon ceramics having a general formula of Ca_(x)Si_(12-2x)Al_(2x)N_(16) with x value(x is the solubility of cation Ca in α-sialon structure)in the range of 0.2-2.2 for compositions lying along the Si_(3)N_(4):1/2Ca_(3)N_(2):3AlN line were synthesized using nano/submicron size starting powder precursors and spark plasma sintering(SPS)technique.The development of calcium stabilized nitrogen rich sialon ceramics at a significantly low sintering temperature of 1500℃(typically reported a temperature of 1700℃ or greater)remains to be the highlight of the present study.The SPS processed sialons were characterized for their microstructure,phase and compositional analysis,and physical and mechanical properties.Furthermore,a correlation was developed between the lattice parameters and the content(x)of the alkaline metal cation in the α-sialon phase.Well-densified single-phase nitrogen rich α-sialon ceramics were achieved in the range of 0.53(3)≤x≤1.27(3).A nitrogen richα-sialon sample possessing a maximum hardness of 22.4 GPa and fracture toughness of 6.1 MPa·m^(1/2) was developed.

喷墨打印纳米ZnO种子制备ZnO微晶棒超疏水表面(英文)

本文主要研究了由ZnO组成的超疏水表面的合成和性能。ZnO本身具有亲水性,但通过改性表面微结构可以生成疏水性表面。采用喷墨打印的方式将纳米ZnO种子打印在载玻片上,形成微凸包,再通过水热法生成ZnO微晶棒以获得超疏水表面,测得表面接触角为153°。同时分析了具有不同微晶棒阵列的超疏水表面接触角变化情况。

Synthesis of zeolite-magadiite composites＂ Effects of co-solvent and aluminum source

The one-pot synthesis of ZSM-5-magadiite, ZSM-23-magadiite, and ZSM-5-ZSM-23-magadiite using isopropylamine and 2-propanol as an organic structure-directing agent and co-solvent, respectively, was studied. Zeolite mixtures were prepared by adding 2-propanol （0 to 10wt%） to the reaction solu- tion. The intergrowth of composites was observed when 2-propanol was introduced as a co-solvent into the reaction mixture. Synthesized samples were characterized by X-ray diffraction, field-emission scan- ning electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. The results revealed that the amount of 2-propanol and source of aluminum influenced the nature of the zeolite-magadiite composites formed.

12-Tungstophosphoric acid niched in Zr-based metal-organic framework:a stable and efficient catalyst for Friedel-Crafts acylation

Heteropoly acids(HPA) are well known for their versatile solid acid catalysis in diverse chemical reactions, however they suffer from low surface area(<10 m^2/g) and leaching into the reactions media, which reduce their prospects as industrial catalyst.Herein, a novel hybrid material HPW@Zr-BTC,composed of 12-tungstophoric acid(HPW) and Zr^(Ⅳ)-benzene tri-carboxylate(Zr-BTC) metal-organic framework(MOF), was prepared via one-pot solvothermal method. Excellent HPW loading up to 32.3 wt% was achieved, and HPW@Zr-BTC composite proved to be highly stable, besides the crystalline morphology of Zr-BTC was intact. The catalytic activity of the hybrid composite was explored via Friedel-Crafts acylation of anisole with benzoyl chloride.The 28.2 wt% HPW@Zr-BTC showed excellent catalytic performance, with 99.4% anisole conversion and 97.6% yield(pmethoxybenzophenone) under solvent free conditions. Excellent retention of catalytic activity was achieved after at least five consecutive runs due to non-observable HPW leaching. The promising activity and stability of the catalyst forecasted its potential industrial applications.

Band gap engineered polymeric-inorganic nanocomposite catalysts:Synthesis, isothermal stability, photocatalytic activity and photovoltaic performance

Polymeric-inorganic nanocomposite catalysts were synthesized by facile one-pot chemical polymerization of pyrrole in the presence of titanium dioxide nanoparticles. The electrical, optical, photovoltaic performance of dye sensitized solar cell（DSSC） and visible light driven photocatalytic activities of the nanocomposite were investigated. The prepared nanocomposite displays excellent photo-activity, attaining 100% degradation of methyl orange dye in 60 min under visible light source while 55% for pure TiO_2 under similar experimental conditions. The photovoltaic performance of the polypyrrole-titanium dioxide（PPy-TiO_2） nanocomposite has a 51.4% improvement with a photo-conversion efficiency of 8.07% as compared to pure TiO_2 based DSSC. By comparing the physical mixture of the PPy-TiO_2 nanocomposite and pristine TiO_2, the enhanced activity of the PPy-TiO_2 nanocomposite can be attributed to the reduced charge transfer resistance, outstanding electrical conductance of the PPy, the nano-sized structure of TiO_2 and their synergetic effect. Furthermore, the PPy-TiO_2 nanocomposite shows excellent electrical conductivity and isothermal stability under ambient conditions below 110？C.

Modeling nanomaterial physical properties:theory and simulation

A brief theory and simulation overview for the purpose of design is presented with examples applies to modeling the physical properties,behavior,and phenomena of nanomaterial.This review paper constructs perspectives that consider coupling traditional domains of simulation by novel pathways to produce accurate representations of nanomaterial properties,behavior and phenomena.It is all about size scaling and how different approaches are able to simulate,integrate or simply pass the baton to the next level of complexity.In macroscopic world,the atomic or molecular information alone may not be directly useful.Nor is the bulk information useful in the microscopic world without intimate knowledge of molecular makeup.Therefore,when designing Nanomaterials,knowledge of properties spanning the complete range of size is the prerequisite of a recommended self-consistent approach.In fact,regarding applications in both industry and academia,the simulation first approach often can lead to great savings in time.This review paper focuses mostly on optical and electronic properties but a section is added that provides a segue into mechanical properties for future consideration.

Erratum on “12-tungstophosphoric acid niched in Zr-BTC: a stable and efficient catalyst for Friedel-Crafts acylation” [Sci.China Chem., 2018, 61: 402–411]

Erratum to:Sci China Chem,2018,61:402-411,https://doi.org/10.1007/sll426-017-9182-0 For the above referenced publication[1],there is a correction in the Figure 9.Figure 9 Catalytic activity of pristine Zr-BTC(a),18.6 wt%HPW@Zr-BTC(b),25.2 wt%HPW@Zr-BTC(c).