木材腐朽菌在森林生态系统中的功能

　木材腐朽菌是森林生态系统的重要组成部分 ,在森林生态系统中起着极为重要的降解还原作用 ,主要包括担子菌门非褶菌目、子囊菌门盘菌纲和半知菌类的部分真菌 ,能全部或部分降解木材中的木质素、纤维素和半纤维素 ,其降解机制有 3种 :白色腐朽、褐色腐朽和软腐朽 .木材腐朽菌与生态系统中其它生物关系密切 ,为很多昆虫、鸟类提供营养 ,有些昆虫也能使木腐菌得到传播 .保护木材腐朽菌的生物多样性是保护森林生态系统、维护生态系统健康的重要因素 .

中国城市形状的时空变化

基于国家资源环境数据库动态土地利用数据,计算了1990年和2000年我国31个大城市的形状指数。结果表明,从1934年～1990年的56年间城市形状从紧凑趋于非紧凑、分散;而在1990年～2000年10年间,由于受到城市建设用地控制增强的影响,城市形状趋于紧凑。从1934年～1974年间,在20个可比较的城市中有14个城市形状指数增加、6个城市形状指数减少。从1974年～1990年间,在22个可比较的城市中各有11个城市的形状指数增加和减少。从1990年～2000年间,31个城市中有11个城市的形状指数增加、20个城市形状指数减少。一些城市的形状指数在不同时间段变化十分剧烈。例如,兰州市是在1934年～1974年间形状指数增加最多的城市,而在1974年～1990年阶段则形状指数减少最多的城市。同样,武汉和昆明则是在1974年～1990年阶段形状指数增加量最大的城市,而在1990年～2000年阶段则是形状指数减少量最大的城市。这或许说明在城市规划和城市建设中,有时人们还未真正认识到城市形状的重要性,往往只有当城市形状变化到严重地影响人们的生产、生活和环境时,才发现形状存在的缺陷。

Online study of the formation of PA6 droplets in PP matrix under shear flow

Breakup process of polyamide 6 (PA6) in polypropylene (PP) matrix under shear flow was online studied by using a Linkam CSS 450 stage equipped with optical microscopy. Both tip streaming and fracture breakup modes of PA6 droplets were observed in this study. It was reported that the droplet would break up by tip streaming model when the radio of the droplet phase viscosity to the matrix phase viscosity (n(r) = n(d)/n(m)) is smaller than 0.1 (Taylor, Proc R Soc London A 1934, 146, 501; Grace, Chem Eng Commun 1982, 14, 225; Bartok and Mason, J Colloid Sci 1959, 14, 13; Rumscheidt and Mason, J Colloid Sci 1961, 16, 238; de Bruijn, Chem Eng Sci 1993, 48, 277). However, the tip streaming model was observed even when the viscosity ratio was much greater than 0.1 (n(r) = 1.9). In this study for the tip streaming mode, small droplets were ruptured from the tip of the mother droplet. On the other hand, the mother droplet was broken into two or more daughter droplets with one or several satellite droplets between them for the fracture mode. It was found that PA6 droplet was much elongated at first, and then broke up via tip streaming or fracture to form daughter droplets or small satellite droplets with the shape of fiber or ellipse.

Strontium-based initiator system for ring-opening polymerization of cyclic esters

An amino isopropoxyl strontium (Sr-PO) initiator, which was prepared by the reaction of propylene oxide with liquid strontium ammoniate solution, was used to carry out the ring-opening polymerization (ROP) of cyclic esters to obtain aliphatic polyesters, such as poly(epsilon-caprolactone) (PCL) and poly(L-lactide) (PLLA). The Sr-PO initiator demonstrated an effective initiating activity for the ROP of epsilon-caprolactone (epsilon-CL) and L-lactide (LLA) under mild conditions and adjusted the molecular weight by the ratio of monomer to Sr-PO initiator. Block copolymer PCL-b-PLLA was prepared by sequential polymerization of epsilon-CL and LLA, which was demonstrated by H-1 NMR, C-13 NMR, and gel permeation chromatography. The chemical structure of Sr-PO initiator was confirmed by elemental analysis of Sr and N, H-1 NMR analysis of the end groups in epsilon-CL oligomer, and Fourier transform infrared (FTIR) spectroscopy. The end groups of PCL were hydroxyl and isopropoxycarbonyl, and FTIR spectroscopy showed the coordination between Sr-PO initiator and model monomer gamma-butyrolactone. These experimental facts indicated that the ROP of cyclic esters followed a coordination-insertion mechanism, and cyclic esters exclusively inserted into the Sr-O bond.

Strain H-2-419-4 of Haematococcus pluvialis induced by ethyl methanesulphonate and ultraviolet radiation

Two strains H-2-410 and H-2-419 were obtained from the chemically mutated survivors of wild Haematococcus pluvialis 2 by using ethyl methanesulphonate (EMS). Strains H2-410 and H2-419 showed a fast cell growth with 13% and 20% increase in biomass compared to wild type, respectively. Then H-2-419-4, a fast cell growth and high astaxanthin accumulation strain, was obtained by exposing the strain H2-419 to ultraviolet radiation (UV) further. The total biomass, the astaxanthin content per cell, astaxanthin production of H-2-4194 showed 68%, 28%, and 120% increase compared to wild H. pluvialis 2, respectively. HPLC (High Performance Liquid Chromatography) data showed also an obvious proportional variation of different carotenoid compositions in the extracts of H2-4194 and the wild type, although no peak of carotenoids appeared or disappeared. Therefore, the main compositions in strain H-2-419-4, like its wild one, were free of astaxanthin, monoester, and diester of astaxanthin. The asexual reproduction in survivors after exposed to UV was not synchronous, and different from the normal synchronous asexual reproduction as the mother cells were motile instead of non-motile. Interestingly, some survivors from UV irradiation produced many mini-spores (or gamete?), the spores moved away from the mother cell gradually 4 or 5 days later. This is quite similar to sexual reproduction described by Elliot in 1934. However, whether this was sexual reproduction remains questionable, as no mating process has been observed.

山西堡子湾金矿角砾岩带控矿规律、成矿时代及隐伏矿体定位预测

The Puziwan gold deposit is located at the northern boundary of the North China platform where there are very favorable ore-forming conditions. The deposit is a medium-sized gold deposit associated with silver and copper polymetallic minerallization which were closely related to cryptoexplosive processes and fluidization and underwent multi-epoch superposition of mineralization. The mineralization consists of cryptoexplosive breccia-type, fluidizing-type, porphyry-type, quartz vein-type, etc. The ore-controlling law of ore-bearing brecciated zone is systematically studied in the paper. The shape, scale and attitude of ore bodies are dominat in the upper, the ore bodies of fluidizing breccia-type are dominant in the upper and the middle part, the porphyry-type ore bodies are dominant in the bottom. The quartz vein-type ore bodies are impenetrated in all the brecciated zone. The metallogenic epoch of Puziwan gold deposit is collated and stipulated. The Rb-Sr isochron age of quartz porphyry (wall rock) is 233 Ma, refering to the Ar-Ar age of gold-bearing quartz, excluded the former conclusion that the so-called metallogenic epoch (245.9Ma) is in Indosinian epoch. The nonage metallogenic age of Buziwan gold deposit shoule be in the Yanshanian epoch (142.5Ma). By applying the sub-specimen sampling technique, the Rb-Sr isochron age of gold-bearing pyrites in late mineralization epoch is dated to be 64 Ma. In conclusion, the metallogenetic epoch of Puziwan gold deposit is in late Yanshanian-early Himalayan epoch. On the above basis, the metallogenic model of the "train type" and new texture model of ore deposit are established. by applying the methods of geology, shallow seismic exploration, remote sensing, partial geochemical extraction and the study of inclusions in the late granite porphyry, the author has made the metallogenic progosis in the depth and the prephery of Puziwan gold deposit and eight prospecting targets are proposed.