利用掺杂诱导的金属-N活性位点和带隙调控提升石墨相氮化碳的光催化产氢性能

由于石墨相氮化碳(g-C3N4)的独特结构和性质,特别是其具有合适的能带结构位置及可调控的晶体结构,被广泛应用于光催化产氢反应中.然而,纯相氮化碳具有较快的光生电荷复合速率,这使其光催化产氢活性较低.目前,利用非金属或过渡金属原子掺杂可有效提升电荷分离速度,从而提高光催化产氢活性.相比于非金属掺杂,g-C3N4的三嗪环...     

Doped Sol-Gel Films for Silica-on-Silicon Photonic Components

Further expansion of optical communication systems depends strongly on the development of cheap component technologies for functions such as switching, demultiplexing and amplification. Silica-on-silicon is increasingly recognised as the best approach to low cost integrated optics for such applications, but so far the functionality is limited. The purpose of NODES, a basic research collaboration sponsored by the European Union under the programme ESPRIT, has been to examine the application of sol-gel to a highly functional silica-on-silicon technology. In particular, the project has investigated film processing and characterisation, rare-earth doping for amplification, and semiconductor nanocrystallite doping for nonlinear functions. This paper presents the background and context to this work, summarises the technical results obtained, and discusses requirements and challenges for successful application of sol-gel in photonics.     

Thermostating in capillary electrophoresis

Summary The use of high voltages across a electrophoresis capillary will increase the temperature of the buffer due to Joule heating. As a result temperature control in CE is rather important since variations in the buffer temperature will result in changes in the pH of the buffer, peak shape, migration time, reproducibility, efficiency, 3-D structure of macromolecular analytes, etc. Six different thermostating systems have been evaluated: (i) natural convection, (ii) fan, (iii) home-made and (iv and v) two commercially available high-speed air and a (vi) liquid thermostated device. In all cases the temperature of the buffer in the capillary is calculated according to the temperature-conductivity relationship. For this purpose two parameters are introduced describing temperature control: the temperature onset (δT) and the temperature rise factor (α). From these results, it can be concluded that high speed air thermostating can be as efficient as liquid thermostating.     

Steam-carbon gasification catalyzed by calcium: Assessment of the porous structure of active carbons from plum stones and synthetic active carbons

A need for an elaboration of the methods for synthesis and characterization of activated carbons with a requisite porous structure has existed for a long time. One of the methods giving possibility for creating controlled mesopore and micropore structures deals with the steam gasification of various carbon materials. In this work the effects of calcium catalyst on the catalytic steam gasification of active carbons from plum stones and porous polymers are presented. Determination of micropores capacity and specific adsorption in mesopores have been performed by means of the _s method, but adsorption on the heterogeneous solids was described by the integral equation with various local isotherms. This equation has been solved by the regularization method. Based on this method the changes in structural parameters of active carbons depending on the amount of calcium catalyst were estimated.Nomenclature d width of slit-like micropore - F(x) distribution function of the half-width - p vapor pressure of sorbate - p/p _N relative pressure - PSAC Plum Stone Active Carbon - average pore radius, nm - S ₁ relative limit of the validity of experimental point on the adsorption isotherm in the computations by means of regularization method - SAC Synthetic Active Carbon - S _BET specific surface area calculated by means of BET method, m²/g - S _mes mesopore surface area, m²/g - S _mic micropore surface area, m²/g - T absolute temperature, K - V _mes sorption capacity of mesopores, cm³/g - V _mic sorption capacity of micropores, cm³/g - V _p sorption capacity of pores, cm³/g - w/w weight in weight concentration - x half-width of slit-like micropore, nm - x ₁ maximum of half-width of micropore slit, nm - average half-width of slit-like micropore, nm - X _min-X _max integration limits of thex Greek Letters Greek Letters variance of average half-width of slit-like micropore, nm² - local relative filling of micropores - total relative filling of micropores     

Selective Formation of Spinel Iron Oxide in Thin Films by Complexing Agent-Assisted Sol-Gel Processing

The structure of iron oxide was controlled by regulating the hydrolytic polymerization of aquo iron complexes with organic polydentate ligands such as diols. Iron oxides were prepared by calcining the precursor polymers obtained from iron nitrate nonahydrate and diols. When the diols were 1,2-pentanediol, 1,2-hexanediol and 1,2-octanediol, α-Fe₂O₃ with corundum structure appeared exclusively or as the main crystalline phase, in spite of the amount of diol used and the calcination temperature. In the case of 1,2-decanediol and 1,2-dodecanediol, when five moles of the diols were used to one mole of iron nitrate and the calcination temperatures were below 400°C, ψ-Fe₂O₃ with spinel structure appeared as the main phase and, when less than five moles of the diols were used, α-Fe₂O₃ appeared exclusively or as the main phase, irrespective of the calcination temperature. This tendency was also observed in thin films. Thus, a transparent magnetic film composed of γ-Fe₂O₃ could be prepared by applying a benzene solution of the iron polymer, obtained with 5 equivalents of 1,2-decanediol, on quartz and calcining the gel film at 350°C.     

Characterisation of Sol-Gel TiO2 Films by Etching

This article describes the SmartKom Companion, one of three demonstrators developed within the SmartKom project whose goal has been to provide an intuitive and intelligent interface for non-expert users to everyday computer-based applications in different scenarios of use. Conceived for the SmartKom Mobile scenario, the Companion allows intuitive multimodal interaction for drivers and pedestrians. The development of the SmartKom prototypes was constantly accompanied by Wizard-of-Oz experiments as well as system evaluations at different stages of the project. Some usability evaluation results relative to the SmartKom Companion will also be presented.     

The application of the measurement uncertainty concept to in-process control in pharmaceutical development

 Any analytical data is used to provide information about a sample. The "possible error" of the measurement can be of extreme importance in order to have complete information. The measurement uncertainty concept is a way to achieve quantitative information about this "possible error" using an estimation procedure. On the basis of the analytical result, the chemist makes a decision on the next step of the development process. If the uncertainty is unknown, the information is not complete; therefore this decision might be impossible. The major problem for the in-process control (IPC) procedure is that not only the repeatability but also the intermediate precision (which expresses the variations within laboratories related to different days, different analysts, different equipment, etc.) has to be good enough to make a decision. Unfortunately, the statistical information achieved from one single analytical run only gives information about the repeatability. This paper shows that the estimation of the measurement uncertainty for IPC is a way to solve the problem and gives the necessary information about the quality of the procedure. An example demonstrates that an estimate of uncertainty based on the standard deviations of an analytical method gives a value similar to one based on the standard deviations obtained from a control chart. Therefore, the estimation is both a very useful and also a very cost-effective tool. Though measurement uncertainty cannot replace validation in general, it is a viable alternative to validation for all methods that will never be used routinely. Received: 24 May 1996 Accepted: 10 August 1996     

Coacervates as models of membraneless organelles

Coacervates are condensed liquid-like droplets, usually formed with oppositely charged polymeric molecules. They have been studied extensively in colloid and interface science for their remarkable material properties. The liquid–liquid phase separation underlying coacervate formation also plays an important role in the formation of various membraneless organelles (MLOs) that are found in many living cells. Therefore, there is an increasing interest to use well-characterized coacervates as in vitro models that mimic specific aspects of MLOs. Here, we review five aspects – physical and chemical properties, hierarchical organization, uptake selectivity, formation dynamics, and maturation – that are of particular interest and discuss how useful coacervates are to better understand these aspects of MLOs.     

Facile Surfactant-, Reductant-, and Ag Salt-free Growth of Ag Nanoparticles with Controllable Size from 35 to 660 nm on Bulk Ag Materials

Morphologically and dimensionally controlled growth of Ag nanocrystals has long been plagued by surfactants or capping agents that complicate downstream applications, unstable Ag salts that impaired the reproducibility, and multistep seed injection that is troublesome and time-consuming. Here, we report a one-pot electro-chemical method to fast (∼2 min) produce Ag nanoparticles from commercial bulk Ag materials in a nitric acid solution, eliminating any need for surfactants or capping agents. Their size can be easily manipulated in an unprecedentedly wide range from 35 to 660 nm. Furthermore, the Ag nanoparticles are directly grown on the Ag substrate, highly desirable for promising applications such as catalysis and plasmonics. The mechanistic studies reveal that the concentration of Ag⁺ in the diffusion layer nearby the surface, controlled by the magnitude and duration of voltage, is critical in governing the nanoparticle formation (<1.3 mM) and its dimensional adjustability.     

Electrochemical Peptide-Based Sensors for Foodborne Pathogens Detection

Food safety and quality control pose serious issues to food industry and public health domains, in general, with direct effects on consumers. Any physical, chemical, or biological unexpected or unidentified food constituent may exhibit harmful effects on people and animals from mild to severe reactions. According to the World Health Organization (WHO), unsafe foodstuffs are especially dangerous for infants, young children, elderly, and chronic patients. It is imperative to continuously develop new technologies to detect foodborne pathogens and contaminants in order to aid the strengthening of healthcare and economic systems. In recent years, peptide-based sensors gained much attention in the field of food research as an alternative to immuno-, apta-, or DNA-based sensors. This review presents an overview of the electrochemical biosensors using peptides as molecular bio-recognition elements published mainly in the last decade, highlighting their possible application for rapid, non-destructive, and in situ analysis of food samples. Comparison with peptide-based optical and piezoelectrical sensors in terms of analytical performance is presented. Methods of foodstuffs pretreatment are also discussed.