Active fixturing: literature review and future research directions

Fixtures are used to fixate, position and support workpieces and represent a crucial tool in manufacturing. Their performance determines the result of the whole manufacturing process of a product. There is a vast amount of research done on automatic fixture layout synthesis and optimisation and fixture design verification. Most of this work considers fixture mechanics to be static and the fixture elements to be passive. However, a new generation of fixtures has emerged that has actuated fixture elements for active control of the part–fixture system during manufacturing operations to increase the end product quality. This paper analyses the latest studies in the field of active fixture design and its relationship with flexible and reconfigurable fixturing systems. First, a brief introduction is given on the importance of research of fixturing systems. Secondly, the basics of workholding and fixture design are visited, after which the state-of-the-art in active fixturing and related concepts is presented. Fourthly, part–fixture dynamics and design strategies which take these into account are discussed. Fifthly, the control strategies used in active fixturing systems are examined. Finally, some final conclusions and prospective future research directions are presented

Oviposition response of the mosquito, Culex quinquefasciatus to the secondary metabolite(s) of the fungus, Trichoderma viride

Secondary metabolites produced by Trichoderma viride, a deuteromycetes fungus, under submerged culture condition were formulated and evaluated for oviposition attractancy against gravid females of Culex quinquefasciatus mosquito. At a concentration of 10 µg ml-1 the formulation showed remarkable attractancy with an oviposition active index (OAI) of +0.52. When the oviposition attractancy of the formulation was compared with a known oviposition attractant, p-cresol, both at 10 µg ml-1, the former was found to be more attractive to result in 70% egg laying than the later with 30% egg laying. Thin layer chromatography fractions of the secondary metabolites showed that a fraction with Rf value of 0.88 was highly active as oviposition attractant with an OAI of +0.65. Further work on identification of the active principle(s) of the microbial formulation might lead to an oviposition attractant useful in mosquito vector management

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Not AvailableSugarcane synthesizes a complex mixture of phytoalexins in response to inoculation with Colletotrichum falcatum Went, causative agent of red rot. To determine induction and accumulation of these compounds, field grown sugarcane plants of two varieties viz., Co 93009 and CoC 671 which are resistant and susceptible to red rot respectively, were inoculated with C. falcatum and tissue extracts were analyzed by HPLC at different intervals after inoculation for the presence of phytoalexins. Analyses of HPLC profiles revealed the induction of five major compounds in response to pathogen inoculation/injury. Among the five detected compounds only two were found to be induced specifically due to pathogen inoculation. One of the two pathogen induced compounds was found to be accumulated only in the resistant variety but completely absent in the susceptible variety. Using standards, the two pathogen induced compounds were identified as luteolinidin and apigeninidin and the results revealed that these phytoalexins induced specifically in red rot resistant variety in response to attempted pathogen infection and susceptible variety failed to synthesize these compounds. The results suggest the possible role of these compounds in red rot resistanceNot Availabl