Design of Streambank Stabilization with Geogrid Reinforced Earth Systems

<p>Chemical bond plays a central role in the description of the physicochemical properties of molecules and solids and it is essential to several fields in science and engineering, governing the material’s mechanical, electrical, catalytic and optoelectronic properties, among others. Due to this indisputable importance, a proper description of chemical bond is needed, commonly obtained through solving the Schrödinger equation of the system with either molecular orbital theory (molecules) or band theory (solids). However, connecting these seemingly different concepts is not a straightforward task for students and there is a gap in the available textbooks concerning this subject. This work presents a chemical content to be added in the physical chemistry undergraduate courses, in which the framework of molecular orbitals was used to qualitatively explain the standard state of the chemical elements and some properties of the resulting material, such as gas or crystalline solids. Here in Part 1, we were able to show the transition from Van der Waals clusters to metal in alkali and alkaline earth systems. In Part 2 and 3 of this three-part work, the present framework is applied to main group elements and transition metals. The original content discussed here can be adapted and incorporated in undergraduate and graduate physical chemistry and/or materials science textbooks and also serves as a conceptual guide to subsequent disciplines such as quantum chemistry, quantum mechanics and solid-state physics.</p>

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Industrial Ecology of the Paper Industry

Water Science & Technology ◽

10.2166/wst.1999.0690 ◽

1999 ◽

Vol 40 (11-12) ◽

pp. 21-24

Author(s):

Tapio Pento

Keyword(s):

Systems Engineering ◽

Industrial Ecology ◽

Raw Materials ◽

Paper Industry ◽

Waste Recycling ◽

Optimal Recovery ◽

Natural Systems ◽

Earth Systems ◽

Controversial Area ◽

Recycling Systems

Industrial ecology (IE) is a biological concept applied to industrial structures. The basic concepts of IE include regional, intra-firm and product-based waste recycling systems as well as the principle of upward and downward cascading. In best current examples of regional systems, several parties are in an industrial waste re-use symbiosis. Paper industry has learned to arrange the recovery and re-use of its products on distant markets, even up to a level where indications of exceeding optimal recovery and re-use rates already exist through deteriorated fibre and product quality. Such occurrences will take place in certain legislative-economic situations. Paper industry has many cascade levels, each with their internal recovery and recycling, as well as many intra-firm, regional, and life cycle ecology structures. As an example of prospects for individual cascading routes, sludges may continue to be incinerated, but the route to landfills will be closed. The main obstacles of legislative drive toward better IE systems are in many cases existing laws and political considerations rather than economic or technical aspects. The study and practice of engineering human technology systems and related elements of natural systems should develop in such a way that they provide quality of life by actively managing the dynamics of relevant systems to reduce the risk and scale of undesirable behavior and outcomes. For the paper industry, earth systems engineering offers several development routes. One of them is the further recognition of and research on the fact that the products of the industry are returned back to the carbon cycle of the natural environment. Opportunities for modifying current earth systems may also be available for the industry, e.g. genetically modified plants for raw materials or organisms for making good quality pulp out of current raw materials. It is to be recognized that earth systems engineering may become a very controversial area, and that very diverse political pressures may determine its future usefulness to the paper industry.

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