香港近海水体光学特性分析及色素浓度反演模式研究

香港近海大约1800平方公里，海岸带水体与旅游娱乐、水产养殖、工业用冷却水源、废水排放以及航运等密切相关。香港近海水体成分复杂，海域东部为半封闭海湾，叶绿素浓度较高，较易发生赤潮；海域西部属于河口环境，是珠江入海区域。由于水体光学特性受多种因素影响，了解海域水质特征并发展适合于海域的生物光学算法，对香港近海水质生态环境保护及海域的综合开发利用是非常必要的。针对本研究海域，本文主要进行水体光学特性分析及色素浓度反演模式研究，希望对水下光学分析及反演算法发展有所贡献。 根据2001年3月－5月在香港临近海域现场调查取得的实测资料，本文对该海域水体吸收光谱进行分析，讨论了总悬浮物浓度TSM，叶绿素a浓度与总颗粒物吸收光谱、浮游植物色素吸收光谱及非色素颗粒吸收光谱之间的系列关系；开发了该海域叶绿素a浓度与色素吸收系数aph(λ)的经验模型，且具有良好的相关性；拟合出黄色物质和非色素颗粒吸收光谱斜率经验值，经验证效果良好。 此外，本文分别用剖面数据外推方法及水体光谱模拟方法完成对水下表面遥感反射率光谱的推导。将外推结果与模拟结果进行比较，模拟光谱效果较好，但在绝对数量值上模拟值较外推值稍低。 水体组分反演模式方面，本文建立了反演低浓度区域叶绿素a浓度的半分析算法，在研究区域反演结果与实测值相比平均相对误差约在45%以内；利用Lee提出的准分析算法模式进行水体总悬浮物吸收系数的反演试验，试验结果与实测值相比有较大误差，误差主要来源于缺少实测散射数据，难以得到适合该海区的散射模型；最后对OC2和OC4经验算法在该海域进行验证，由于有限的数据集，还难以将算法区域化。

Effects of physical parameter range on dimensionless variable sensitivity in water flooding reservoirs

The similarity criterion for water flooding reservoir flows is concerned with in the present paper. When finding out all the dimensionless variables governing this kind of flow, their physical meanings are subsequently elucidated. Then, a numerical approach of sensitivity analysis is adopted to quantify their corresponding dominance degree among the similarity parameters. In this way, we may finally identify major scaling law in different parameter range and demonstrate the respective effects of viscosity, permeability and injection rate.

Femtosecond filamentation and supercontinuum generation in silver-nanoparticle-doped water

The authors report the investigation of filament and supercontinuum generation by focusing a femtosecond laser beam into water doped with silver nanoparticles. The silver nanoparticles enhance the nonlinear optical response of water, leading to broadening of supercontinuum spectra in self-focused femtosecond filaments. During the propagation of the supercontinuum light in the filament, the silver nanoparticles preferentially scatter the short-wavelength light near the plasmon resonant wavelength peak, followed by the scattering of the long-wavelength light. Thus, a side view of the filament shows a full-color spectrum in the visible range, which is herein called "rainbow filament." (c) 2007 American Institute of Physics.

The role of MC1R gene in buffalo coat color

Melanocortin-1 receptor (MC1R) plays a major role in pigmentation in many species. To investigate if the MC1R gene is associated with coat color in water buffalo, the coding region of MC1R gene of 216 buffalo samples was sequenced, which included 49 black river buffalo (Murrah and Nili-Ravi), 136 swamp buffalo (Dehong, Diandongnan, Dechang, Guizhou, and Xilin) with white and gray body, and 31 hybrid offspring of river buffalo Nili-Ravi (or Murrah) and swamp buffalo. Among the three variation sites found, SNP684 was synonymous, while SNP310 and SNP384 were nonsynonymous, leading to p.S104G and p.I128M changes, respectively. Only Individuals carrying homozygote E-BR/E-BR were black. The genotype and phenotype analysis of the hybrid offspring of black river buffalo and gray swamp buffalo further revealed that the river buffalo type allele E-BR or the allele carrying the amino acid p.104S was important for the full function of MC1R. The in silico functional analysis showed that the amino acid substitutions p.G104S and p.M128I had significant impact on the function of MC1R. Above results indicate that the allele E-BR or the allele carrying the amino acid p.104S was associated with the black coat color in buffalo.

Preparation of colorless ionic liquids "on water" for spectroscopy

Although colorless ionic liquids (ILs) are most desirable, as synthesized they frequently bear color, despite appearing pure by most analytical techniques. It leads to some uncertainties and limits for the fundamental research and applications of ILs, such as spectroscopy. Using 1-butyl-3-methylimidazolium bromide (BMIMBr), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) and 1-hexyl-3-methylimidazolium bromide (HMIMBr) as models, we demonstrated that following classic preparing method except that the water was added as solvent, colorless ILs could be facilely prepared. Neither critical pre-treatment of starting materials and pre-cautions during the reaction nor time-consuming and costly post-decolor-purification was needed, The effects of "on water" reaction conditions on preparing colorless IL and the reason why using water as solvent could produce colorless ILs were also preliminary investigated.

Spectrophotometric determination of water content in alcohol organic solvents

In this work, the absorption spectral characteristics and color-change reaction mechanism of cobalt(II) chloride(COCl2) in alcohol organic solvents has been investigated in the presence of water, and then the optimum conditions for determining the water content in the solvents were selected. Results indicated that the absorption spectra Of COCl2 in alcohols decreased with the increment of water content. At the maximum absorption wavelength of 656 nm, there were good linear relationships between the logarithm of the absorbance and the water content in organic solvents such as ethanol, n-propanol, iso-propanol and n-butanol with related coefficients in the range of 0.9996 similar to 0.9998. For determining water content in organic solvents, this method is simple, rapid, sensitive, reproducible and environmentally friendly. Furthermore, the linear range cannot restrict determination of the water content in organic solvents. This method had been applied to determine the water content in ethanol and n-butanol with satisfactory recovery of water in n-butanol between 98.41%-101.29%.