Ab initio molecular orbital calculations on ion-molecule and ion pair-molecule complexes of the water-lithium cyanide system

Ab initio molecular orbital (MO) calculations with the 3-21G and 6-31G basis sets were performed on a series of ion-molecule and ion pair-molecule complexes for the H2O + LiCN system. Stabilisation energies (with counter-poise corrections), geometrical parameters, internal force constants and harmonic vibrational frequencies were evaluated for 16 structures of interest. Although the interaction energies are smaller, the geometries and relative stabilities of the monohydrated contact ion pair are reminiscent of those computed for the complexes of the individual ions. Thus, interaction of the oxygen lone pair with lithium leads to a highly stabilised C2v structure, while the coordination of water to the cyanide ion involves a slightly non-linear hydrogen bond. Symmetrical bifurcated structures are computed to be saddle points on the potential energy surface, and to have an imaginary frequency for the rocking mode of the water molecule. On optimisation the geometries of the solvent shared ion pair structures (e.g. Li+cdots, three dots, centered OH2cdots, three dots, centered CN−) revealed a proton transfer from the water molecule leading to hydrogen bonded forms such as Li-O-Hcdots, three dots, centered HCN. The variation in the force constants and harmonic frequencies in the various structures considered are discussed in terms of ion-molecular and ion pair-molecule interactions.

Consistency limits behavior of bentonites exposed to sea water

This article examines the changes in interparticle forces brought about on prolonged contact (1 year period) of a bentonite clay with artificial seawater. The study is undertaken with the purpose of identifying the physico-chemical factors that impart a nonswelling character to smectite clays deposited in marine environments. Results show that equilibration of the bentonite clay with artificial seawater (total pore salinity approximately 42 gL-1) for a 1 year period does not lead to any mineralogical changes in the clay specimens; however, their exchangeable cation positions become prominently dominated by magnesium ions. The consistency limits of the seawater-equilibrated bentonite was determined on stepwise leaching to lower salinities. The predominance of diffuse double-layer repulsion forces in the pore salt concentration range of 42 gL-1 to 1.1 gL-1 caused an increase in the liquid limits of the seawater-equilibrated bentonite specimens on reducing the salinity in the corresponding range (42 gL-1 to 1.1 gL-1). The attraction forces, however, prevail over the repulsion forces at salt concentrations <1.1 gL-1 and cause a decrease in liquid limit of the clay specimens with reduction in pore salinity, which is typical of nonswelling clays. The attraction forces cause aggregation of the clay unit layers into domains that break down on sodium saturation of the clay specimens. It is inferred that the physico-chemical factors responsible for the nonswelling character of the seawater-equilibrated bentonite specimens at pore salt concentrations below 1.1 gL-1 are inadequate to explain the nonswelling character of smectite-rich Ariake marine clays. The lower consistency limits of the Ariake marine clays in comparison to the nonswelling character, seawater-equilibrated bentonite specimens is attributed to a relative deficiency of interparticle forces in the Ariake marine clay.

Airborne sulphur and lake water acidification in Finland.

Tiivistelmä: Ilman rikkilaskeuma ja järvien happamoituminen Suomessa.

Water Management in Cambodia Resources and Relations

In Cambodia, water has a special purpose as a source of life and livelihoods. Along with agriculture, fishing and forest use, industry, hydropower, navigation and tourism compete for the water resources. When rights and responsibilities related to essential and movable water are unclear, conflicts emerge easily. Therefore, water management is needed in order to plan and control the use of water resources. The international context is characterized by the Mekong River that flows through six countries. All of the countries by the river have very different roles and interests already depending on their geographical location. At the same time, water is also a tool for cooperation and peace. Locally, the water resources and related livelihoods create base for well-being, for economical and human resources in particular. They in turn are essential for the local people to participate and defend their rights to water use. They also help to construct the resource base of the state administration. Cambodia is highly dependent on the Mekong River. However, Cambodia has a volatile history whose effects can be seen for example in population structure, once suspended public institutions and weakened trust in the society. Relatively stable conditions came to the country as late as in the 1990s, therefore Cambodia for example has a weak status within the Mekong countries. This Master s thesis forms international, national and local interest groups of water use and analyzes their power relations and resources to affect water management. The state is seen as the salient actor as it has the formal responsibility of the water resources and of the coordination between the actions of different levels. In terms of water use this study focuses on production, in management on planning and in power relations on the resources. Water resources of Cambodia are seen consisting of the Mekong River and Tonle Sap Lake and the time span of the study is between the years 1991 and 2006. The material consists of semi-structured interviews collected during summer 2006 in Finland and in Cambodia as well as of literature and earlier studies. The results of the study show that the central state has difficulties to coordinate the actions of different actors because of its resource deficit and internal conflicts. The lessons of history and the vested interests of the actors of the state make it difficult to plan and to strengthen legislation. It seems that the most needed resources at the central state level are intangible as at the village level instead, the tangible resources (fulfilling the basic needs) are primarily important. The local decision-making bodies, NGOs and private sector mainly require legislation and legitimacy to support their role. However, the civil society and the international supporters are active and there are possibilities for new cooperation networks. Keywords: Water management, resources, participation, Cambodia, Mekong

Molecular theory of ion solvation dynamics in water, acetonitrile and methanol: A unified microscopic description of collective dynamics in dipolar liquids

A recently developed microscopic theory of solvation dynamics in real dipolar liquids is used to calculate, for the first time, the solvation time correlation function in liquid acetonitrile, water and methanol. The calculated results are in excellent agreement with known experimental and computer simulation studies.