词的二重性

语言中的词,以具有指称客观事物的功能做为语言的建筑材料成为词汇系统中的成员,以具有语言结构造句的功能充当语法系统中的单位。这是词的二重性。如果单就词汇系统中的词来说也有二重性,这是本文要谈的。 语言是一个民族全体成员传递信息、进行交际的工具,为全民族成员所共同理解和运用。词的形式(语音形式和书写形式)及其所代表的内容是该民族全体成员所共同规定的,

槐魂

槐魂张金良，刘贵珍在那群山簇拥的家乡小山村，老队长的家门前曾有一棵四人难以合抱，被几代人铭记在心的大槐树。那槐树中心已空，但枝千粗壮得像一条条巨龙伸向四面八方。夏天枝繁叶茂，像一把墨绿色的大伞，在槐树的树干分叉处又长出一棵如臂粗壮的桑树。祖辈们常年累...

Scalable preparation of porous silicon nanoparticles and their application for lithium-ion battery anodes

Nanostructured silicon has generated significant excitement for use as the anode material for lithium-ion batteries; however, more effort is needed to produce nanostructured silicon in a scalable fashion and with good performance. Here, we present a direct preparation of porous silicon nanoparticles as a new kind of nanostructured silicon using a novel two-step approach combining controlled boron doping and facile electroless etching. The porous silicon nanoparticles have been successfully used as high performance lithium-ion battery anodes, with capacities around 1,400 mA.h/g achieved at a current rate of 1 A/g, and 1,000 mA.h/g achieved at 2 A/g, and stable operation when combined with reduced graphene oxide and tested over up to 200 cycles. We attribute the overall good performance to the combination of porous silicon that can accommodate large volume change during cycling and provide large surface area accessible to electrolyte, and reduced graphene oxide that can serve as an elastic and electrically conductive matrix for the porous silicon nanoparticles.

All-solid-state electrochromic devices based on WO3‖NiO films:material developments and future applications

Electrochromism refers to the persistent and reversible change of optical properties by an applied voltage pulse.Electrochromic(EC)devices have been extensively studied because of their commercial applications in smart windows of green buildings,display devices and thermal control of equipments.In this review,a basic EC device design is presented based on useful oxides and solid-state electrolytes.We focus on the state-of-the-art research activities related to the structures of tungsten oxide(WO_3)and nickel oxide(NiO),summarizing the strategies to improve their EC performances and further applications of devices.

Template-directed fabrication of 3D graphene-based composite and their electrochemical energy-related applications

Graphene shows great potentials in electrochemical energy-related areas.To enhance its properties and corresponding electrochemical performance,recently,three-dimensional(3D)graphene-based materials especially monolithic porous graphene with encapsulated functional nanomaterials have arisen much research interest for electrochemical catalysis,lithium ion batteries(LIBs),lithium–sulfur batteries,supercapacitors,etc.With the enhanced structure properties such as interconnected graphene network,high volume-specific surface area and electronic conductivity,3D monolithic graphene is more suitable for the fabrication of composite electrode materials in real devices.In this article,we discuss recent development in fabricating monolithic 3D graphene and their composites using template-directed methods and their applications in electrochemical energy-related areas.

Synthesis, characterization and photocatalytic application of H_3PW_(12)O_(40)/BiVO_4 composite photocatalyst

A series of H3PW12O40/BiVO4 composite with different H3PW12O40 loadings were prepared using a hydrothermal and impregnation method. The prepared composites were characterized by XRD, Raman, SEM, XPS, and DRS techniques. The bandgap of the composite was narrower compared with the as-prepared pure BiVO4 . As a novel photocatalytic material, the photocatalytic performance of the H3PW12O40/BiVO4 composite was investigated by the degradation of methylene blue (MB) dye solution under visible light irradiation and compared with that of pure BiVO4 . The results revealed that the introduction of H3PW12O40 could improve the photocatalytic performance and different concentrations of H3PW12O40 resulted in different photocatalytic activities. The highest activity was obtained by the sample with a loading HPW concentration of 10 wt%. The reason for the enhanced photocatalytic activities of H3PW12O40/BiVO4 samples was also discussed in this paper. Moreover, the H3PW12O40/BiVO4 composites retained the catalytic activity after four repeated experiments.

Bioinspired robust nanocomposites of cooper ions and hydroxypropyl cellulose synergistic toughening graphene oxide

The hierarchical micro/nanoscale layered formation of organic and inorganic components of natural nacre, results in abundant interracial interactions, providing an inspiration for fabricating bioinspired nanocomposites through constructing the interfacial interactions. Herein, we demonstrated the synergistic interfacial interactions of hydrogen bonding from hydroxypropyl cellu- lose and ionic bonding from copper ions upon the reduced graphene oxide based bioinspired nanocomposites, which show the integrated tensile strength, toughness and excellent fatigue-resistant property, as well as high electrical conductivity. These ex- traordinary properties allow this kind of bioinspired nanocomposites to potentially utilize in the fields of aerospace, flexible electronics devices, etc. This study also opens a door for fabricating excellent mechanical performance graphene-based bioin- spired nanocomposites via synergistic interfacial interactions in the future.

2D materials via liquid exfoliation:a review on fabrication and applications

Since graphene was discovered, the study of two-dimensional(2D) materials with atomic thickness has become a hot spot. To prepare different 2D materials,different methods have been groped, such as mechanical exfoliation, chemical vapor deposition(CVD), liquid-phase exfoliation. This review mainly introduced the sonication liquid-phase exfoliation, an effective method to prepare 2D materials. Compared with mechanical exfoliation and CVD methods, liquid-phase exfoliation is convenient and costeffective and provides high yield. We focused on both theoretical and experimental details of this method. This method was reviewed according to the development of 2D materials from graphene, h-BN to transition metal chalcogenides(TMDs) and black phosphorus nanosheets.We discussed the applications of liquid-exfoliated 2D materials including micro- and nanoelectrical devices,photoelectric devices, and energy storage devices.

Recent progress on nanostructured conducting polymers and composites:synthesis,application and future aspects

Conducting polymers （CPs） have been widely investigated due to their extraordinary advantages over the traditional materials, including wide and tunable electrical conductivity, facile production approach, high mechanical stability, light weight, low cost and ease in material processing. Compared with bulk CPs, nanostructured CPs possess higher electrical conductivity, larger surface area, superior electro- chemical activity, which make them suitable for various ap- plications. Hybridization of CPs with other nanomaterials has obtained promising functional nanocomposites and achieved improved performance in different areas, such as energy sto- rage, sensors, energy harvesting and protection applications. In this review, recent progress on nanostructured CPs and their composites is summarized from research all over the world in more than 400 references, especially from the last three years. The relevant synthesizing experiences are outlined and abundant application examples are illustrated. The ap- proaches of production of nanostructured CPs are discussed and the efficacy and benefits of newest trends for the pre- paration of multifunctional nanomaterials/nanocomposites are presented. Mechanism of their electrical conductivity and the ways to tailor their properties are investigated. The re- maining challenges in developing better CPs based nanoma- terials are also elaborated.

Wet-spinning assembly of nitrogen-doped graphene film for stable graphene-polyaniline supercapacitor electrodes with high mass loading

Graphene-polyaniline(GP)composites are promising electrode materials for supercapacitors but possessing unsatisfied stability,especially under high mass loading,due to the low ion transmission efficiency and serious pulverization effect.To address this issue,we propose a scalable method to achieve highly wettable GP electrodes,showing excellent stability.In addition,our results demonstrate that the performance of electrodes is nearly independent of the mass loading,indicating the great potential of such GP electrodes for practical devices.We attribute the remarkable performance of GP to the delicate precursor of nitrogen doped graphene film assembled by wet-spinning technology.This report provides a strategy to promote the ion penetrating efficiency across the electrodes and deter the pulverization effect,aiming at the practical GP supercapacitor electrodes of high mass loading.

Dendrimer/inorganic nanomaterial composites: Tailoring preparation,properties,functions,and applications of inorganic nanomaterials with dendritic architectures

Inorganic nanomaterials have a variety of fascinating properties and a wide range of promising applications.However,they often suffer from instability and poor processibility.To solve it,dendrimers,a special family of macromolecules having a unique three-dimensional architecture,provide one of the excellent solutions.In addition,the site-selective functionalization of the specific elements in the dendritic structure endows the nanohybrid system new functions and applications.Inspired by such ideas,a variety of dendrimer/inorganic nanomaterial composites have been designed and exploited.This review article selects a number of representative examples,and illustrates their preparation,characterization,properties,and applications.The influence and the unique features that originate from the introduced dendritic structures are particularly discussed.