Interaction of Freshly Precipitated Silica Gel with Aqueous Silicic Acid Solutions under Ambient and Near Neutral pH-conditions: A Detailed Analysis of Linear Rate Law

Interaction of freshly precipitated silica gel with aqueous solutions was studied at laboratory batch experiments under ambient and near neutral pH-conditions. The overall process showed excellent reversibility: gel growth could be considered as an opposite process to dissolution and a linear rate law could be applied to experimental data. Depending on the used rate law form, the resulting rate constants were sensitive to errors in parameters/variables such as gel surface area, equilibrium constants, Si-fluxes, and reaction quotients. The application of an Integrated Exponential Model appeared to be the best approach for dissolution data evaluation. It yielded the rate constants k _dissol ∼ (4.50 ± 0.68) × 10⁻¹² and k _growth ∼ (2.58 ± 0.39) × 10⁻⁹ mol m⁻² s⁻¹ for zero ionic strength. In contrast, a Differential Model gave best results for growth data modeling. It yielded the rate constants k _dissol ∼ (1.14 ± 0.44) × 10⁻¹¹ and k _growth ∼ (6.08 ± 2.37) × 10⁻⁹ mol m⁻² s⁻¹ for higher ionic strength (I ∼ 0.04 to 0.11 mol L⁻¹). The found silica gel solubility at zero ionic strength was somewhat lower than the generally accepted value. Based on the and standard Gibbs free energy of silica gel formation was calculated as and −850,318 ± 20 J mol⁻¹, respectively. Activation energies for silica gel dissolution and growth were determined as and respectively. An universal value for growth of any silica polymorph, is not consistent with the value for silica gel growth, which questions the hypothesis about one unique activated complex controlling the silica polymorph growth.     

An index to assess maritime importance in the European Atlantic economy

Successive marine policies set by the European Union identify the maritime sectors as crucial drivers for growth and jobs in the EU economy. The design of marine policies and the assessment of the importance of the maritime economy need empirical support that provides the basic data to help the decision-making process. This paper proposes a metric, in the form of a synthetic index, to measure and compare the importance of the maritime sectors in the European Atlantic area. The index scores can be used to assess the position of each Atlantic region so that it is possible to compare its performance to the rest of the area. The results show the relative weight of the maritime sectors in the European Atlantic regions and the high heterogeneity among them. Analyzing the maritime economy with this index can provide guidance for the design of economic policies to identify and revitalize the regions with greater potential for Blue Growth in the Atlantic area. This may help to put into perspective the importance of the maritime economy and can serve to improve the socio-economic dimension of the use of marine waters.     

微齿喜马拉雅低额溞生长及种群增长的研究

于1990年6月在哈尔滨市东北林业大学实验林场一水池中采到微齿喜马拉雅低额溞，根据实验结果应用生物统计学方法对它的生长和种群增长进行研究。结果表明，在不同温度条件下性成熟时间与水温的关系为，雌性（10-30°C）：h=8072t^-1.313（r=0.985, P＜0.01）；雄性（5-25°C）：h=1074t^-0.855（r=0.9844，P＜0.01）。在20±1°C条件下，其体长增长模型为：l_t=3.334-2.7345e^-0.1117t。龄期（x）与年龄（t，d）的关系为：雌体：t=0.07169x²＋1.3808x-1.7361；雄体：t=0.8425x²＋2.534x-1.8600。内禀增长率（r_m）为0.4076。种群增长呈“logistic”型，其方程式为：y=3625/[1+e^{(3.848-0.164t)}]。     

温度对草鱼能量收支的影响

于１９９２年４月－１９９２年５月在２２，２６及３０℃，以莴苣叶为食物，不限量摄食，测定草鱼的能量收支。结果表明，草鱼摄食率及生长率均随温度上升而增加；最大摄食率与水温的关系温度对食物能分配于能量收支各组分的比例没有显著影响，在３个温度测定的平均能量收支式为：１００ｃ＝２９．８９Ｆ＋３．３０Ｕ＋５２．４８Ｒ＋１４．３４Ｇ，式中Ｃ为食物能，Ｆ为排粪能，Ｕ为排泄能，Ｒ为代谢能，Ｇ为生长能。     

硒对极大螺旋藻生长及含硒量的影响

用０．４ｍｇ／Ｌ硒培养极大螺旋藻时，３５℃与１６０μｍｏｌ／ｍ＾２．ｓ的光温条件有利于螺旋藻生长和对硒的累积，在此种光温条件下，４０ｍｇ／Ｌ硒以下均促进藻的生长，其中１２ｍｇ／Ｌ硒的效果最大；超过６０ｍｇ／Ｌ硒就有抑制作用；４００ｍｇ／Ｌ硒以下藻即死亡。     

Regression and Time Series Analysis of the World Oil Peak of Production: Another Look

This paper analyzes world oil production data as a population/resource growth model. Both US and world oil production data are analyzed in terms of the logistic growth curve. It is shown that the logistic growth curve, while a suitable model for the American data, is not a suitable model for world oil production. A flexible family of curves which allows a wide range growth rates is considered. Using a nonlinear regression, one can predict various peak dates and total recoverable resources using different curves which all fit the data indistinguishably well.     

基于德尔菲法的江西省“三农”气象服务效益评估

利用江西省2012年统计年鉴和20个农业气象服务体系和农村气象灾害防御体系（简称＂两个体系＂）建设实施县的专家测评调查结果（针对农业、林业、牧业、渔业4大重点行业和电力、水利、交通3个高相关行业的调查结果）,采用德尔菲法（专家评估法）,对2010—2013年江西省＂三农＂气象服务效益进行分析评估。结果表明,2010—2012年江西省农业总产值气象服务贡献率稳定在4.00%—4.90%,2012年＂三农＂气象服务对农业总产值效益的新增贡献率为2.6%。2010—2013年＂三农＂气象服务效益评估值分别为76.04、108.14、104.36和116.07亿元,投入产出比为1：3.3—1：7.8,2013年3个高相关行业的产值贡献率为4.0%—5.0%。     

温度、盐度及光照强度对海链藻(Thalassiosira sp.)生长的影响

报道了温度、盐度、光照对海洋硅藻海链藻生长的影响。结果表明 ,海链藻的适应温度范围比较广 ,从9～27℃都可维持正常生长 ,15～21℃为其适温范围 ;在盐度15～35范围内 ,盐度对海链藻的影响不大 ,在盐度为20时 ,海链藻获得最大的生长率;此外 ,海链藻具有广泛的光适应性 ,在7.5～90μmol/(m2·s)的光照范围内均可正常生长,并随着光强的增加生长率不断提高     

Scenarios for the Future Population of Sydney

The period 1996-2001 has witnessed a refocusing of population growth on Sydney and Melbourne as both cities have developed significant concentrations of so-called 'new economy' jobs and taken on, to greater or lesser extents, the characteristics of global cities. The consequence of these trends, for Sydney most particularly, is population growth. This paper establishes this demographic reality by describing recent demographic trends in Sydney and possible future scenarios for Sydney's population, given differing levels of fertility, internal migration and international migration. A related future trend is also traced--that the number of households in Sydney will grow more rapidly than the population due to changes in household structure. This raises the issue of how and where these households will be accommodated, given the relative land shortage in the Sydney Statistical Division and given that there is no doubt that planners in New South Wales will be attempting to maintain and enhance Sydney's status as a global city. In sum, the paper argues that Sydney planners should be preparing for growth of around one million people in the next 20 years and a further one million in the following 30 years. To maintain that potential future residents of Sydney can be redirected to other parts of New South Wales is a vain hope.     

平原湖区抑螺防病林池杉生长规律的研究

通过对血吸虫病重疫区江汉平原池杉抑螺防病林进行观测调查和树干解析,研究探讨了平原湖区池杉的树高、胸径和材积生长规律,并建立了随年龄变化的数学模型。池杉树高早期生长快,20a之后增长速度明显下降,连年生长量和平均生长量在15a左右相交。胸径生长以4～14a最为迅速,连年生长量和平均生长量均呈先升后降趋势并在12～14a相交。材积平均生长量在前24a一直呈上升趋势,连年生长量在22a时达到最大。材积生长率和形数随树龄增加而逐渐减小,形数在6a后趋于稳定。应根据池杉生长规律,科学营建抑螺防病林,实现综合效益最大化。