城市群生态安全格局构建:概念辨析与理论思考

城市群是城市发展到一定阶段通过城市间物流、人流和能流高度融合而形成的区域性复合生态系统，如何保障城市群生态安全与健康发展成为当前关注的热点问题。本研究系统分析了生态安全、城市生态安全与城市群生态安全的内涵。认为狭义上城市群生态安全侧重于城市群内部生态空间优化和生态系统服务功能提升，重点关注城市群地区生态用地空间优化与"三生空间"（生态、生活及生产空间）的合理布局。广义上的城市群生态安全不仅需要考虑城市群内部生态系统结构和功能协调及其生态系统服务的供需平衡，也需要从区域尺度考虑城市群与其他区域之间的协调关系。城市群生态安全格局构建的目的则是保障城市群内部区域一体化协调发展，满足人们日常生活的基本需求，实现城市群与区域之间物流、能流和人流的有序流通。在城市群生态安全格局构建时，除了遵循生态安全一般性原则外，还需要遵循以下原则：①生态系统服务供需平衡尺度效应；②生态安全保障的阈值效应；③生态安全格局的空间联动效应。最后文章提出了城市群生态安全格局构建的基本思路和技术路径。     

Imidacloprid and Related Compounds: Structure and Water Solubility of N-Alkyl Derivatives of Imidacloprid

An intramolecular hydrogen bond between NH???O₂N in insecticide, imidacloprid (1), and its nitromethylene analog 15 was proved by NMR and IR spectra. That electron delocalization over their planar moieties was disrupted by alkylation at the imidazolidine nitrogen atom is demonstrated by the hypsochromic shifts in UV and deshielding effect in NMR spectra. Interestingly, the N-alkyl derivatives (C1-5) had greater water solubility than 1, although increasing alkyl chain length decreased the solubility. The hydrophilicity of the alkyl derivatives would result from remote charge heads being formed as a result of the conjugation disruption by alkylation, while the hydrophobicity of 1 could be ascribed to the charge distribution over the conjugated system coupled with the intramolecular H-bonding. The greater water solubility of 15 than 1 and contrastively small solubility of the cyanoimine analogue are discussed based on the difference in their steric crowding.     

Screening of lipid high producing mutant from rhodotorula glutinis by low ion implantation and study on optimization of fermentation medium

In order to obtain lipid producing strain with high-yield, the wild type stain Rhodotorula glutinis was treated by low ion implantation, and optimization of fermentation medium for higher lipid yield was carried out using mutant strain. It was found that the strain had a higher positive mutation rate when the output power was 10 keV and the dose of N⁺ implantation was 80 × 2.6 × 10¹³ ions/cm². Then a high-yield mutant strain D30 was obtained through cid-heating coupling ultrasonic method and lipid yield was 3.10 g/L. Additionally, the surface response method was used to optimize fermentation medium. The three significant factors (glucose, peptone, KH₂PO₄) were optimized using response surface methodology (RSM), and the optimized parameters of fermentation medium were as follows: glucose 73.40 g/L, peptone 1.06 g/L and KH₂PO₄ 3.56 g/L. Finally the fermentation characteristic of high-yield mutation strain D30 was studied, when fermentation time was 10 days, which lipid yield increased to 7.81 g/L. Fatty acid composition of the lipid was determined by GC, and the most represented fatty acids of mutant D30 were C16:0 (11.4 %), C16:1 (5.66 %), C18:1 (49.3 %), and C18:2 (27.0 %).     

Visualization of mitochondrial coupling factor F1(ATPase) by freeze-drying

It is known that the negatively stained preparations of inner mitochondrial membrane display characteristic ∼9 nmF ₁ (ATPase) knobs projecting from the matrix surface. Freeze-etch studies have reported the absence of such knobs from the “etched” surface of the inner mitochondrial membranes. We have demonstrated their presence on the surface of SMP (submitochondrial particles) prepared by freeze-drying for transmission electron microscopy. This identification has been substantiated by comparison with the freeze-dried TU particles (trypsin-urea treated SMP) that are devoid ofF ₁ (ATPase). It has been suggested that a layer of water molecules is strongly adsorbed to the surface of SMP and does not sublime during normal freeze-“etching.”     

Antibody induced capping and endocytosis of surface antigens in Naegleria fowleri

Naegleria fowleri, a free-living amoeba-flagellate responsible for primary amoebic meningoencephalitis in man, was observed to cap and internalize surface-bound antibody. These results suggest that the ability of N. fowleri to remove antibody from its surface may allow the amoeba to resist the action of the host's immune system.     

Optimization of lipase-catalyzed synthesis of acetylated EGCG by response surface methodology

(−)-Epigallocatechin-3-O-gallate (EGCG) acetylated derivatives, which can be widely used as a natural antioxidant in both lipid containing food and cosmetic applications, were prepared by lipase catalyzed acylation of EGCG with vinyl acetate. Response surface methodology (RSM) and 5-level-4-factor central composite rotatable design (CCRD) were employed to evaluate the effects of synthesis parameters, such as reaction time (6–10 h), temperature (30–50 °C), enzyme amount (1.5–2.5% (w/w) of substrate), and substrate molar ratio of EGCG to vinyl acetate (0.5–1.5) on conversion of EGCG. By using multiple regression analysis, the experimental data were fitted to a second order polynomial model. The most suitable combination of variables was 40 °C, 2.12%, 10 h and 1.13 for the reaction temperature, the enzyme amount, the reaction time, and EGCG/vinyl acetate mole ratio, respectively. At these optimal conditions, the conversion yield reached 87.37%. The presence of mono-, di- and tri-acetylated derivatives in acetylated EGCG was confirmed by LC–MS-MS and identified as 5″-O-acetyl-EGCG, 3″, 5″-2-O-acetyl-EGCG and 5′, 3″, 5″-3-O-acetyl-EGCG by NMR.     

Inter-strain Variability of Structural Proteins in Tetrahymena*

SYNOPSIS The high molecular weight proteins found in isolated pellicles of Tetrahymena have been compared in several individual strains within the genus using SDS polyacrylamide gel electrophoresis. Three variants of the B-protein of epiplasm (MW 174,000; 155,000; 145,000) and 2 of the C-protein (MW 140,000; 122,000) were found among the strains examined. No variation was observed in the major kinetodesmal fiber protein (MW 250,000). The variation found between strains in the proteins of a structure which is (as far as we know) the same in all strains indicates a disjunction between evolutionary change at the 2 levels of organization. The taxonomic implications of the observed variation in structural proteins in Tetrahymena are discussed.