Mechanisms Of Members Research Articles

Controllable design on failure mode for steel frames considering regional collapse-resistant mechanism

Controlling the collapse area of a structure is a direct collapse-resistant design requirement. However, existing theoretical models for collapse-resistant design establish the demand–capability relationship by considering only the lower-limit capacity of the damaged regions of a structure, and ignore the limit state of the surrounding structures. With the development of chain failure behaviors in a damaged structure, the member mechanism cannot resist accumulated unbalanced loads. Therefore, a higher level collapse-resistant mechanism should be considered in the design to ensure that the structure still has the controllable and expected failure modes. To this end, this paper proposes a collapse-resistant design concept with multilevel collapse-resistant behaviors characterized by a steel frame structural system with force-controlled members (FCMs). The FCM was designed based on the upper- and lower-limit internal force-controlled equations proposed in this study. Under the designed load, following the failure of a key member, unbalanced loads are redistributed throughout the remaining structure via a member mechanism. A regional mechanism is triggered (connection between FCM and surrounding regions is disconnected) to control the failure mode of the structure if a certain region fails. Two lines of defense at the member and regional levels are provided to prevent progressive collapse. To evaluate the efficacy of the proposed method, corresponding full-scale steel frame models were designed and tested using reliable numerical models based on the proposed method. The results indicated that the collapse-resistant behaviors of the structural system at the member and regional levels meet the design requirements.

Effect of amino acids and amines on the activity of the recombinant ι-carbonic anhydrase from the Gram-negative bacterium Burkholderia territorii

We here report a study on the activation of the ι-class bacterial CA from Burkholderia territorii (BteCAι). This protein was recently characterised as a zinc-dependent enzyme that shows a significant catalytic activity (k cat 3.0 × 105 s−1) for the physiological reaction of CO2 hydration to bicarbonate and protons. Some amino acids and amines, among which some proteinogenic derivatives as well as histamine, dopamine and serotonin, showed efficient activating properties towards BteCAι, with activation constants in the range 3.9–13.3 µM. L-Phe, L-Asn, L-Glu, and some pyridyl-alkylamines, showed a weaker activating effect towards BteCAι, with KA values ranging between 18.4 µM and 45.6 µM. Nowadays, no information is available on active site architecture, metal ion coordination and catalytic mechanism of members of the ι-group of CAs, and this study represents another contribution towards a better understanding of this still uncharacterised class of enzymes.

N-Methyltransferases of Caffeine Biosynthetic Pathway in Plants.

Caffeine (Cf) is one of the important components of plant-derived drinks, such as tea, coffee, and cola. It can protect soft tissues from being infected by pathogens and is also medically beneficial for human health. In this review, we first introduced the Cf biosynthesis pathways in plants and the related N-methyltransferases (NMTs), with a focus on the current research status of the substrate specificity, structural basis for substrate recognition, and catalytic mechanism in members of the caffeine synthase gene family. In addition, we addressed the expression characteristics and potential regulatory mechanisms of NMTs and also projected the future research directions. The goal was to summarize the Cf biosynthetic pathway and related NMTs in plants and to provide the molecular basis for regulating the caffeine biosynthesis, so as to effectively guide future tea and coffee breeding.

Numerical Simulation on the Form of Reinforcement of Reinforced Concrete Beam with Openings

In order to research the stress performance of reinforced concrete beam with different forms of reinforcement around the openings, a numerical simulation on reinforced concrete beam with circle openings is made by using the finite element software. The constitutive relation of concrete offered by the 2010 edition of code for design of concrete structures and the concrete damaged plasticity model is adopted in this article. The damage factor is introduced in the process of modeling, which can reflect the damage of beams with different forms of reinforcement directly and help to reveal the failure mechanism of members. Thus we can propose the optimization of reinforcement method.

Itinéraires d’engagement et de désengagement au sein d’associations sportives en milieu rural

An analysis of the social life of rural sports clubs, via the lens of social links, leads us to observe the mechanisms of members’ involvement and disengagement. The qualitative and quantitative data used in our research indicate that the temporality of rural sports associations exercises a decisive influence on the structuring of sports connections between members. The articulation of individual and collective logics then causes differentiation, in terms of intensity, or even breaking up. By following the paths of these rural sports practitioners within the clubs, from entry to exit, and with regard to the construction or deconstruction of these social relationships, we can discover the role of ‘club spirit’ in the various modalities of associative involvement as well as the various phases, situations and contexts leading to disengagement. This article allows us therefore to evaluate the structuring and/or relegating impact of the reality of sports activities in the countryside.

The four foundational groups required for a successful ICME approach

This article briefly outlines some of the roles of four foundational groups in fostering rapid growth and implementation of Integrated Computational Materials Engineering (ICME). These roles include development of ICME-related computational, experimental, and cyberinfrastructure tools, and training of the future ICME workforce, in order for ICME to realize its great potential. The four foundational groups considered here include: corporations, government organizations, universities, and professional societies. Finally, a discussion is provided of how materials societies can play an important role in convening the four foundational groups, and providing the venues and mechanisms for members from these groups to integrate and work together to enable ICME to flourish.

Topology Optimization of Strut-and-Tie Models in Reinforced Concrete Structures Using an Evolutionary Procedure

This paper presents a performance based evolutionary topology optimization method for automatically generating optimal strut-and-tie models in reinforced concrete structures with displacement constraints. In the proposed approach, the element virtual strain energy is calculated for element removal, while a performance index is used to monitor the evolutionary optimization process. By systematically removing elements that have the least contribution to the stiffness from the discretized concrete member, the load transfer mechanism in the member is gradually characterized by the remaining elements. The optimal topology of the strut-and-tie model is determined from the performance index history, based on the optimization criterion of minimizing the weight of the structure while the constrained displacements are within acceptable limits. Several examples are provided to demonstrate the capability of the proposed method in finding the actual load transfer mechanism in concrete members. It is shown that the proposed optimization procedure can produce optimal strut-and-tie models that are supported by the existing analytical solutions and experimental evidence, and can be used in practice, especially in the design of complex reinforced concrete members where no previous experience is available.

Haemaphysalis (Kaiseriana) mageshimaensis (Ixodoidea: Ixodidae): Human and Wild and Domestic Mammal Hosts, and Distribution in Japan, Taiwan, and China

Haemaphysalis (Kaiseriana) mageshimaensis Saito and Hoogstraal, originally described from specimens from vegetation (and laboratory-reared) from Mage Island, Japan, is now recorded from over 1,800 additional samples taken in Taiwan and nearby Lu-tao and Lan-yu islands, and in southeastern China and Hong Kong. Adults, and often also nymphs, parasitize wild carnivores (palm civet, leopard cat, and tiger), the barking deer, humans, domestic goats, and other domestic mammals. Numerous larvae parasitized a palm civet and a leopard cat. Fewer larvae were taken from rats, birds, and domestic goats and dogs. The field data show no evidence of parthenogenetic reproduction. From field observations of sick goat and cattle hosts, the frequency of biting humans, and an unusually wide pattern of immaturestage host relationships, this parasite is a candidate for medical, veterinary, and biological investigation. Haemaphysalis (Kaiseriana) mageshimaensis Saito and Hoogstraal (1973), described from samples taken on vegetation (and laboratoryreared) on Mage Island, a few miles south of Kyushu, Japan, is now recorded from Taitung Hsien of southeastern Taiwan, nearby Lu-tao and Lan-yu islands, and southeastern China and Hong Kong. Known hosts of adults, and often also of nymphs, are wild carnivores, the muntjac or barking deer, and the domestic goat, cow, dog, buffalo, and pig. Larvae, together with adults and nymphs, were numerous in two collections from wild carnivores and numbered one or two in a few collections from rats, birds, and domestic goats and dogs. Heavy infestations occurred on domestic goats and on wild carnivores and a muntjac. Some goat and cattle hosts were observed to be ill. In Japan, this species is considered to be a likely vector of bovine Theileria sp. (Saito and Hoogstraal, loc. cit.). From these observations, as well as from the several records of Received for publication 29 March 1974. * From Research Projects MR041.09.01-0037A 6GI and -0133B 6GI, Bureau of Medicine and Surgery, Department of the Navy, Washington, D. C. The opinions and assertions contained herein are the private ones of the authors and are not to be construed as official or as reflecting the views of the Department of the Navy or of the naval service at large. This investigation was supported in part by Agreement 03-005-1 between the NIAID (NIH) and NAMRU-3. t U. S. Naval Medical Research Unit Number Three (NAMRU-3), American Embassy, Cairo, Arab Republic of Egypt. + NAMRU-2, Taipei, Taiwan. biting humans during a few days of exploring Lan-yu Island, H. (K.) mageshimaensis is a candidate for more precise and extensive biological, medical, and veterinary investigation. Saito (in Saito and Hoogstraal, loc. cit.) showed the ability of the Japanese population of H. (K.) mageshimaensis to reproduce parthenogenetically in the laboratory but no evidence for this phenomenon is found in the field data from Taiwan, Lan-yu, Lu-tao, and China. As in the closely related H. (K.) longicornis Neumann (Hoogstraal et al., 1968), parthenogenesis may be a more or less highly developed survival mechanism in members of this tropical group that have spread and adapted to colder temperate environments.