Ultrastretchable,Tough, and Notch‐Insensitive Hydrogels Formed with Spherical Polymer Brush Crosslinker

Spherical polymer brushes, poly(acrylic acid) (PAA)‐grafted polystyrene nanoparticle (PAA@PS), are employed as the macro‐crosslinker to prepare PAA hydrogels. Benefitting from the innumerable hydrogen bonds between highly entangled PAA chains both in bulk and on the polymer brush, the PAA/PAA@PS hydrogels combine desirable stretchability, toughness, and notch‐insensitivity. The uniaxial tensile tests show a very high fracture elongation up to 9.1 × 10³% while the fracture toughness reaches 3.0 MJ m⁻³ and the maximum swelling ratio of the hydrogel can be 2.0 × 10³ as well. After being loaded with silver nanoparticles, the PAA/PAA@PS hydrogels are employed as a recyclable catalyst successfully.     

To be or not to be – nematic liquid crystals from shape-persistent V-shaped nematogens with the ‘magic angle’

The tetrahedral bending angle in V-shaped nematogens was claimed to be the optimum for finding a biaxial nematic liquid crystal phase. The benzo[1,2-b:4,3-b’]dithiophene core, recently successfully applied as a tetrahedral bending unit in mesogens with lateral flexible chains, is here embedded in a scaffold with only terminal chains, which conventionally promotes the formation of nematic phases at low temperature. A series of new mesogens has been successfully prepared, realising hockey-stick, hockey-stick dimer and V-shaped molecular topologies. Only the hockey-stick mesogens assemble in uniaxial nematic phases over a broad temperature range. Single crystal structure analysis of a hockey-stick and V-shaped compound reveal remarkable similarities with the benzodithiophene core wrapped by aliphatic chains. A model explaining the absence of nematic mesophases in the family of V-shaped, shape-persistent mesogens with terminal aliphatic chains is presented and results in the proposal of a new design for biaxial nematogens.     

布氏折射装置的设计

本文介绍了一种利用布儒斯特原理设计的折射装置，该装置具有原理简单、操作方便、对待测物要求低的特点。     

A dominant subset of V-shaped sequences for a class of single machine sequencing problems

In this note we define a subset of V-shaped sequences, ‘V-shaped about T’, which generalize ‘V-shaped about d’ sequences. We derive a condition under which this subset contains an optimal sequence for a class of single machine sequencing problems. Cost functions from the literature are used to illustrate our results.     

Performance limitation of chirped-fiber-Bragg-grating-based photonic microwave notch filter due to group delay and reflectivity ripples

We investigated the performance limitation of a frequency-tunable photonic microwave notch filter incorporating a chirped fiber Bragg grating (FBG) as a group delay line. In particular, we carried out theoretical and experimental studies to analyze the impact of the reflectivity ripple (RR) and group delay ripple (GDR) in the chirped FBG on the output notch performance. The results of experimental and theoretical analyses performed on a photonic microwave notch filter in which an S-bending-based linearly chirped FBG was incorporated, revealed that the notch depth and notch frequency were significantly affected by imperfections in the chirped FBG. The notch depth was found to be decreased by the RRs, whereas significant fluctuations in the notch frequency were caused by the GDRs. On the basis of the obtained results, we conclude that the RR and the GDR are the fundamental factors that degrade the performance of chirped FBG-based photonic microwave filters.     

三维切口尖端应力应变场

本文利用双重幂级数展开法分析三维切口尖端应力应变奇异性，通过切口边界条件导出切口特征方程，进而求得不同切口内角下特征值序列解答，最后推得切口尖端应力应变场。     

Geometrical effects on shallow donor impurities in quantum wires

We have studied theoretically the impurity binding energy for wires of different shapes (V-shaped quantum wire (V-QWR) and rectangular wire) with a variational procedure without using any coordinate transformation. The effective potential for V-QWR used in this work consists of a square well potential in the z-direction and full graded well potential in the x-direction. Our results are in good agreement with previous theoretical results, found by the coordinate transformation method. Furthermore, it is shown that the impurity binding energy in quantum wires is sensitive to the geometrical effects.     

Median plane localization using a parametric model of the head-related transfer function based on spectral cues

To examine a simulation method for vertical sound localization, and to clarify which peaks and notches in head-related transfer functions (HRTFs) play a role as spectral cues, localization tests in the median plane were carried out using a parametric HRTF model, which is recomposed only of extracted spectral peaks and notches. The results show that the parametric HRTF recomposed using the first and second notches (N1 and N2) and the first peak (P1) provides almost the same localization accuracy as the measured HRTFs. Observations of the spectral peaks and notches indicate that N1 and N2 change remarkably as the source elevation changes, whereas P1 does not depend on the source elevation. In conclusion, N1 and N2 can be regarded as spectral cues, and the hearing system could utilize P1 as the reference information to analyze N1 and N2.     

超前/延误排序问题的进展(英文)

近年来对超前／延误（Ｅ／Ｔ）排序问题进行了广泛的研究．本文总结了对Ｅ／Ｔ排序问题的各种研究中的一些特别领域,虽然没有覆盖所有的新成果,但对该课题有兴趣的读者提供了指导．     

两例弯曲型二酸Zn(Ⅱ)、Cd(Ⅱ)配合物的合成，结构与荧光性质

本文以弯曲型二酸2,2′-azanediyldibenzoic acid(H₂L)为配体，溶液法合成了2个新的配合物[Zn₂(L)₂(H₂O)₂]·H₂O (1)和[(NH₄)₂ Cd(L)₂]·C₂H₅OH (2)。通过X射线单晶衍射分别测定了他们的结构：配合物1属于单斜晶系，空间群为P2₁/c，a=1.487 9(2) nm，b=0.898 9(1) nm，c=1.210 0(2) nm，β=99.211(2)°，V=1.597 3(3) nm³。配体L的羧酸根均为单齿配位，桥连2个锌离子，形成一个零维的[2+2]扭曲环状结构，并由氢键作用连接成二维结构。配合物2属于正交晶系，空间群为Pbcn，a=2.060 2(2) nm，b=1.281 9(1) nm，c=2.246 1(1) nm，V=5.931 9(6) nm³。Cd(Ⅱ)取较少见的羧酸根螯合八配位结构，L与Cd(Ⅱ)也形成了二核环状结构，并通过共用1个镉离子而形成一维的阴离子链，抗衡阳离子为NH₄⁺。链间通过π…π作用堆积成三维结构。此外，还并测定了配体及配合物的荧光性质。