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Purpose: To assess the feasibility of a new shape configuration involving a partially hollow and porous lower part for dental implants. Materials and Methods: Cylindrical zirconia dental implants coated with bioactive glass were fabricated in the laboratory. Each implant has a solid upper part and a partially hollow lower part. It is open at the bottom with holes through the lower cylindrical walls. This hollow and porous configuration permits bone growth into the lower part of the implant that, over time, forms an interlinked network to lock the implant into the alveolar bone. Biomechanical properties of the new design were evaluated through material testing and experiments with dogs. Results: Mechanical testing of bending strength, hardness, fracture toughness, and fatigue life indicated that zirconia implants with the proposed partially hollow configuration can be fabricated to have structural properties comparable to or exceeding the usual requirements for implants. Animal testing suggests that there is appreciable improvement in lock-in strength and osteointegration due to the hollow and porous configuration. Conclusion: The new shape configuration is biomechanically feasible and further research is warranted to improve the design for human use. [Copyright &y& Elsevier]

Abstract: The capacitance of few-electron dielectric spheres differs from the many-electron Gauss model of infinitesimally-divisible charge as a result of the electrostatic interaction of discrete electrons. Minimization of the total classical interaction energy for nanometer-size devices without quantum effects for up to 12 electrons is obtained. Unlike the Gauss model, capacitance is non-constant. The variation of capacitance with N, thus, with voltage, in a non-magnetic, classical domain, opens a new field of discrete charge nanometer-size devices and applies to the general chemistry of nanoparticles. [Copyright &y& Elsevier]

Weeds are a major constraint to crop production, which is of crucial importance for food security in China given its 1.37 billion population. In recent years, an increasing number of herbicide resistant weeds and invasive alien plants have become prevalent and challenging to manage in China as elsewhere in the world. In this review, we provide an overview of several key facets of weed science research in China, including (i) weed community shifts as a result of cropping system and weed management changes, (ii) the status of invasive weeds, (iii) weed management options for the increasing number of herbicide resistant weeds, and (iv) the challenges and opportunities in weed research in China. Invasive weeds in tandem with changes in cropping systems have significantly altered weed communities in crops such as rice (Oryza sativa L.), wheat (Triticum aestivum L.), maize (Zea mays L.), soybean Glycine max (L.) Merr.], cotton (Gossypium hirsutum L.), and oilseed rape (Brassica napus L.). At present, 30 weed species have evolved resistance to 11 herbicide sites of action that includes 48 commonly used herbicides. Although tactics such as crop rotation and biological control have been used to manage some weeds in China, weed control has and continues to rely primarily on herbicides. Research priorities for weed management include developing and implementing a preventive risk assessment framework and a better understanding of the mechanisms that allow some alien weeds to be highly aggressive and difficult to manage. Moreover, the development and evaluation of additional weed management tactics such as breeding competitive crop cultivars, straw mulching, optimizing water management, and site-specific fertilizer and herbicide applications warrant further study. The use of an integrated weed management approach in coming years will rely heavily on a more in-depth understanding of the biological and ecological principles governing weed population dynamics. Approaches such as herbicide resistance weed management (HRWM) programs in tandem with conservation agriculture (CA) can be employed to develop sustainable weed management strategies in cropping systems. • Invasive weeds in tandem with changes in cropping systems have led to weed community shifts in main crops. • More than 500 invasive weeds are an increasing threat to agricultural production and ecosystems in China. • Thirty weed species have evolved resistance to 11 herbicide sites of action in recent years. • Integrated weed management is critically important for sustainable agriculture in China. • Research on weed biological and ecological principles governing weed population dynamics warrants further research attention. [ABSTRACT FROM AUTHOR]

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is applied directly to aquatic and conventional farming systems to control weeds, and is among the most widely distributed pollutants in the environment. Non-target organisms are exposed to 2,4-D via several ways, which could produce toxic effects depending on the dose, frequency of exposure, and the host factors that influence susceptibility and sensitivity. An increasing number of experimental evidences have shown concerns about its presence/detection in the environment, because several investigations have pointed out its potential lethal effects on non-target organisms. In this review, we critically evaluated the environmental fate and behavior of 2,4-D along with its eco-toxicological effects on aquatic, plants and human life to provide concise assessment in the light of recently published reports. The findings demonstrate that 2,4-D is present in a low concentration in surface water of regions where its usage is high. The highest concentrations of 2,4-D were detected in soil, air and surface water surrounded by crop fields, which suggest that mitigation strategies must be implanted locally to prevent the entry of 2,4-D into the environment. A general public may have frequent exposure to 2,4-D due to its wide applications at home lawns and public parks, etc. Various in vivo and in vitro investigations suggest that several species (or their organs) at different trophic levels are extremely sensitive to the 2,4-D exposure, which may explain variation in outcomes of reported investigations. However, implications for the prenatal exposure to 2,4-D remain unknown because 2,4-D-induced toxicity thresholds in organism have only been derived from juveniles or adults. In near future, introduction of 2,4-D resistant crops will increase its use in agriculture, which may cause relatively high and potentially unsafe residue levels in the environment. The recent findings indicate the urgent need to further explore fate, accumulation and its continuous low level exposure impacts on the environment to generate reliable database which is key in drafting new regulation and policies to protect the population from further exposure. [ABSTRACT FROM AUTHOR]

With increasing developments in the Information Technology (IT) outsourcing industry, many enterprises outsource IT services to reduce costs. However, the schedule risk of IT outsourcing (ITO) projects may result in enormous economic losses for an enterprise. In this paper, the principal–agent theory is used to control the schedule risk of ITO projects. A two-level mathematical model is built to describe the decision process of the client and vendors. With an increase to the number of subprojects and activities, the scale of the problem will become very large. The resulting optimization is an NP hard problem with continuous domain. Therefore, a genetic algorithm (GA) is designed to solve the proposed model. Experiments are performed to test the ability of the proposed algorithm. Some insights from simulation analysis – the principal–agent theory and two-level mathematical model – are suitable for describing the cooperative relationship between principle and agent. By comparing with ant colony optimization and simulated annealing, the proposed GA shows strong optimization abilities for convergence, reliability, and efficiency, which is a good tool for this kind of optimization problem. The near-optimal plan reduced the schedule risk of the project remarkably, which is the scientific quantitative proposal for the decision maker. This study provides practitioners insights on relationships of schedule risk and ITO projects, and the design model and algorithms of this paper provides practitioners effective potential method to reduce the schedule risk of ITO projects in their operations. However, the uncertain characteristics of key and multiple factors should be considered in future work. Stochastic Programming and the Monte Carlo Simulation Method are two potential tools for dealing with uncertain factors. Additionally, the proposed GA could potentially be improved in terms of convergence. The advantages of other intelligent algorithms could be applied to the GA in order to improve its searching ability, such as the Taboo mechanism. [ABSTRACT FROM AUTHOR]