Molecular evolution study in China: progress and future promise

China has a large land area with highly diverse topography, climate and vegetation, and animal resources and is ranked eighth in the world and first in the Northern Hemisphere on richness of biodiversity. Even though little work on molecular evolution had

Vitrification of Yunnan Yellow Cattle oocytes: work in progress

The objective of this study was to provide a simple cryopreservation method for oocytes from Yunnan Yellow Cattle and facilitate preservation efforts in this native Chinese breed, which is threatened by agricultural modernization. Cumulus-oocyte complexes (COCs) were collected from slaughterhouse ovaries and matured in vitro for 22-24 h, then selected for cryopreservation. Vitrification in open pulled straws (OPS) or in microdrops on a cooled metal surface (solid surface vitrification, SSV) was compared. The OPS vitrification solution consisted of 20% ethylene glycol (EG) and 20% DMSO. The SSV solution was a mixture of 35% EG, 5% polyvinyl-pyrrolidon (PVP) and 0.4 M trehalose. Vitrified and warmed oocytes were either fertilized in vitro or parthenogenetically activated. The rates of cleavage and development to blastocysts of fertilized oocytes following OPS versus SSV were not statistically different (38.3 and 12.5% versus 35.8 and 6.0%, respectively). The corresponding rates of parthenogenetic development to blastocysts were also not different (8.2 versus 3.5%, respectively). Development to blastocysts of non-vitrified controls following fertilization was significantly higher than that of the vitrified oocytes (22.6%, P < 0.05). These results demonstrate for the first time, that although both OPS and SSV procedures reduced embryonic development, Yunnan Yellow Cattle oocytes are capable of developing to blastocysts following cryopreservation. (C) 2002 Elsevier Science Inc. All rights reserved.

Progress in the evaluation of transgenic fish for possible ecological risk and its containment strategies

Genetically improved transgenic fish possess many beneficial economic traits; however, the commercial aquaculture of transgenic fish has not been performed till date. One of the major reasons for this is the possible ecological risk associated with the escape or release of the transgenic fish. Using a growth hormone transgenic fish with rapid growth characteristics as a subject, this paper analyzes the following: the essence of the potential ecological risks posed by transgenic fish; ecological risk in the current situation due to transgenic fish via one-factor phenotypic and fitness analysis, and mathematical model deduction. Then, it expounds new ideas and the latest findings using an artificially simulated ecosystem for the evaluation of the ecological risks posed by transgenic fish. Further, the study comments on the strategies and principles of controlling these ecological risks by using a triplold approach. Based on these results, we propose that ecological risk evaluation and prevention strategies are indispensable important components and should be accompanied with breeding research in order to provide enlightments for transgenic fish breeding, evaluation of the ecological risks posed by transgenic fish, and development of containment strategies against the risks.

Research progress on algae of the microbial crusts in and and semiarid regions

Microbial crusts are attracting much interest in view of their possible uses in environmental conservation and ecological restoration of the and and semiarid regions. Because algae play an irreplaceable important role in the early formation and the strengthening of microbial crusts, they are paid much more attention to than other cryptogams. In this paper, an overview of the current knowledge on the fine structure and development of microbial crust, focusing on the algal biomass, vertical distribution, succession, influential factors on algae, cohesion of soil stabilization, cementing mechanism for soil particles and the microalgal extracellular polymers is given, with particular emphasis on the authors' researches, and some prospects are put forward as well.

Genome mapping in aquatic animals: Progress and future perspectives

The genome of aquatic animals is poorly understood and information from different taxonomic groups is sketchy. While there have been intensive genomic studies on some fish models, investigations on other fishes and invertebrates have been scarce. Yet there are recently some coordinated studies on genome mapping in a number of aquaculture animals of economic importance. This review summarizes information available on genome mapping of the important fish models and aquaculture animals. The future perspectives of this field of studies are discussed.

Research progress of self-organized Ge quantum dots on Si substrate

A review is presented on recent research development of self-organized Ge/Si quantum dots (QDs). Emphasis is put on the morphological evolution of the Ge quantum dots grown on Si (001) substrate, the structure analysis of multilayer Ge QDs, the optical and electronic properties of these nanostructures, and the approaches to fabricating ordered Ge quantum dots.

Research progress of electronic properties of self-assembled semiconductor quantum dots

Self-assembled semiconductor quantum dot is a new type of artificially designed and grown function material which exhibits quantum size effect, quantum interference effect, surface effect, quantum tunneling-Coulumb-blockade effect and nonlinear optical effect. Due to its advantages of less crystal defects and relatively simpler fabrication technology, this material may be of important value in the research of future nanoelectronic device. In the order of vertical transport, lateral transport and charge storage, recent advances in the electronic properties of this material are brefly introduced, and the problems and perspectives are analyzed.

The research and progress of micro-fabrication technologies of two-dimensional photonic crystal

The novel material of photonic crystal makes it possible to control a photon, and the photonic integration will have breakthrough progress due to the application of photonic crystal. It is based on the photonic crystal device that the photonic crystal integration could be realized. Therefore, we should first investigate photonic crystal devices based on the active and the passive semiconductor materials, which may have great potential application in photonic integration. The most practical and important method to fabricate two-dimensional photonic crystal is the micro-manufacture method. In this paper, we summarize and evaluate the fabrication methods of two-dimensional photonic crystal in near-infrared region, including electron beam lithography, selection of mask, dry etching, and some works of ours. This will be beneficial to the study of the photonic crystal in China.

Investigation progress on key photonic integration for application in optical communication network

Proceeding from the consideration of the demands from the functional architecture of high speed, high capacity optical communication network, this paper points out that photonic integrated devices, including high speed response laser source, narrow band response photodetector high speed wavelength converter, dense wavelength multi/demultiplexer, low loss high speed response photo-switch and multi-beam coupler are the key components in the system. The, investigation progress in the laboratory will be introduced.

Progress of Si-based nanocrystalline luminescent materials

Si-based nanomaterials are some new photoeletronic and informational materials developed rapidly in recent years, and they have potential applications in the light emitting devices, e. g. Si light emitting diode, Si laser and integrated Si-based photoelectronics. Among them are nano-scale porous silicon (ps), Si nanocrystalline embedded SiO2 (SiOx, x < 2.0) matrices, Si nanoquantum dot and Si/SiO2 superlattice, etc. At present, there are various indications that if these materials can achieve efficient and stable luminescence, which are photoluminescence (PL) and electroluminescence (EL), it is possible for them to lead to a new informational revolution in the early days of the 21st century. In this article, we will mainly review the progress of study on Si-based nanomaterials in the past ten years. The involved contents are the fabricated methods, structural characterizations and light emitting properties. Finally, we predicate the developed tendency of this field in the following ten years.

New progress of studies on semiconductor materials

This paper is a review of research and development on semiconductor materials, which covers main scientific activities in this field. The present status acid future prospects of studies on semiconductor materials, such as silicon crystals, GaAs related III-V compound semiconductor materials and GaAs, InP and silicon based quantum well and superlattice materials, quantum wires and quantum dots materials, microcavity and photonic crystals, materials for quantum computation and wide band gap materials, are briefly discussed.