Enhanced superprism effect based on positive/negative lateral shift of reflective beam in a Fabry-Perot filter

It is found that when a light beam is incident obliquely on a thin film Fabry-Perot filter (FPF) from different incident media (air or substrate), the reflective beam will be shifted in both the forward and the backward directions. Based on this inverted spatial dispersion effect, two thin film FPFs with different directional lateral shifts are assembled to get a thin film superprism with a wider dispersion band. The thin film samples are fabricated as well as tested, and the results are in approximate agreement with numerical simulation.     

Cycles in 2-connected graphs

Let be a class of graphs on n vertices. For an integer c, let be the smallest integer such that if G is a graph in with more than edges, then G contains a cycle of length more than c. A classical result of Erdös and Gallai is that if is the class of all simple graphs on n vertices, then . The result is best possible when n-1 is divisible by c-1, in view of the graph consisting of copies of K_c all having exactly one vertex in common. Woodall improved the result by giving best possible bounds for the remaining cases when n-1 is not divisible by c-1, and conjectured that if is the class of all 2-connected simple graphs on n vertices, thenwhere , 2tc/2, is the number of edges in the graph obtained from K_c+1-t by adding n-(c+1-t) isolated vertices each joined to the same t vertices of K_c+1-t. By using a result of Woodall together with an edge-switching technique, we confirm Woodall's conjecture in this paper.     

One-step synthesis of acid carbon and its catalytic activities for the oxathioacetalization

The novel acid carbon has been synthesized successfully via one-step hydrothermal carbonization. The acid carbon owned the morphologies of the spheres with smooth surfaces and the acidity of 2.4 mmol/g. The catalytic activities of the novel acid carbon were investigated through oxathioacetalization. The results showed that the acid carbon owned high activity for the reactions with the average yields over 95%. The advantages of high activity, stability, reusability, low cost for the simple synthetic procedure and wide application to various carbonyl compounds made the acid carbon one of the best choices for the reactions.     

Synthesis and catalytic activity of porous polymer containing ionic liquid structures

A novel porous polymer containing ionic liquid (IL) structures was synthesized via quternization and condensation of 4-vinylpyridine and p-xylylene dichloride. The ionic liquid structures were incorporated in the polymeric framework and for this reason bulky IL molecules can hardly block pores and neutralize active sites. The polymer shows a high BET surface area and easily accessible active sites. Catalytically the polymer is very active in Michael additions with averaged yields over 96.0% achieved after short reaction times. The high BET surface, remarkable activity, operational simplicity, wide applicability and improved stability are the key properties of the polymer.     

2 TPa压力下2169钢的冲击压缩测量

 利用地下爆炸产生的冲击波进行2169钢冲击压缩测量。测量是根据阻抗匹配解方法并且以铁作为标准材料。布置47根接触电探针以确定2169钢和标准材料中的冲击波速度以及冲击波阵面形状。测量出的2169钢冲击压缩参数是：冲击波速度u_s=22.12 km/s，波后粒子速度u_p=13.39 km/s，冲击波压力p=2.31 TPa和压缩比σ=2.53。本测量结果与较低压力下化爆测量结果的外推值的比较表明，两者基本一致。     

Facile syntheses of 1-deoxynojirimycin (DNJ) and 1-deoxymannojirimycin (DMJ)

1-Deoxynojirimycin (DNJ) and 1-deoxymannojirimycin (DMJ) were synthesized through a concise and practicable pathway. A strategy of using carbohydrate derivatives bearing two leaving groups in the preparation of azasugars by di-N-alkylation of amines was developed. The strategy involved the selective partial protection of dibromo alditols.     

Novel solid acid with both Brønsted and Lewis acid sites for biodiesel synthesis

The solid acid with both Brønsted and Lewis acid sites has been synthesized from resorcinol-formaldehyde (RF) resin, hydroxyethylsulfonic acid and copper hydroxyethylsulfonate. The solid acid was applied to catalyze the transesterification of rapeseed oil. The results showed that the novel solid acid was very efficient for the biodiesel synthesis with the yield over 99% even for the rapeseed oil with high water content and both the free fatty acid and triglyceride could be efficiently transformed to the biodiesel products. The regular sphere structure, low cost, high acidity and catalytic activities gave the solid acid great potential for green chemical processes.     

Theoretical and experimental researches of size effect in micro-indentation test

Micro-indentation tests at scales on the order of sub-micron have shown that the measured hardness increases strongly with the indent depth or indent size decreasing, which is frequently referred to as the size effect. However, the trend is at odds with the size-independence implied by conventional elastic-plastic theory. In this paper, strain gradient plasticity theory is used to model the size effect for materials undergoing the micro-indenting. Meanwhile, the micro-indentation experiments for single crystal copper and single crystal aluminum are carried out. By the comparison of the theoretical predictions with experimental measurements, the micro-scale parameter of strain gradient plasticity theory is predicted, which is fallen into the region of 0.8–1.5 micron for the conventional metals such as copper (Cu), aluminum (Al) and silver (Ag). Moreover, the phenomena of the pile-up and sink-in near micro-indent boundary are investigated and analyzed in detail.     

Novel Efficient Acidic Ionic Liquid Polymer for Biodiesel Synthesis from Waste Oils

Kinetics and Catalysis - A highly stable acid ionic liquid polymer was prepared via the polymerization of 1-vinyl-3-(propyl-3-sulfony) imidazolium 4-styrenesulfonate. Both the cations and anions...