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排序方式: 共有198条查询结果,搜索用时 15 毫秒
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M. S. Giri Nandagopal Rahul Antony S. Rangabhashiyam Nidhin Sreekumar N. Selvaraju 《Microsystem Technologies》2014,20(7):1249-1272
Transdermal drug delivery has given cardinal contribution to medical practices. First-generation transdermal delivery of small, lipophilic, low-dose drugs and second-generation delivery systems using chemical enhancers, non-cavitational ultrasound and iontophoresis have also resulted in various clinical products provides added functionality. Third-generation delivery systems using microneedles, thermal ablation, microdermabrasion, electroporation and cavitational ultrasound targeting skin’s barrier layer of stratum corneum. Microneedles acquire pronounced intrigue in recent days. Currently, microneedles are advancing through clinical trials for delivery of macromolecules and vaccines, such as insulin, parathyroid hormone and influenza vaccine. The review explains about the concept of transdermal drug microneedle system comprising of microreservoir, micropumps, flow sensors, types of microneedles. Various researches carried out on these components of microneedle system is elaborately discussed in this review. 相似文献
3.
P. V. Ananthapadmanabhan K. P. Sreekumar P. V. Ravindran N. Venkatramani 《Journal of Materials Science》1993,28(6):1655-1658
Plasma-sprayed TiB2 coatings (50–600 m thick) on alumina substrates have been developed and characterized. X-ray diffraction studies, thermal analysis and oxygen analysis of the coatings show that there is appreciable oxidation of TiB2 during the spray process. Partial oxidation of the boride during spraying strongly influences the electrical conductivity of the coatings, which is found to be 100–1000 times less than that of pure TiB2. Although use of argon as shield gas during the spray process brings down the resisitivity substantially, partial oxidation of TiB2 could not be totally avoided. 相似文献
4.
Robot motion planning (RMP) develops a precise path between start and goal points for mobile robots in an unknown environment. RMP is a complex task when it needs to be planned for a group of robots in a coordinated environment with leader–follower relationship. The planned path might change depending upon the number of robots and the decision made. The decision made by each robot depends on the feedback received based on the subsequent action taken by other robots. In addition, the computational complexities depend upon factors such as communication between robots, the influence of moving obstacles and environment in which they are interacting. In order to explore further in the area of motion planning, it is felt that a comprehensive survey of available literature would support researchers working in RMP and hence the present paper. This paper reviews around 152 articles published in various international journals and conferences with more emphasis on articles published after 1960. In this work, recent activities carried out in the field of path planning for mobile robotics are critically evaluated and problems faced by the researchers are also highlighted. The focus is towards implementation of probabilistic algorithms, including Probabilistic Road Map and Simultaneous Localization and Mapping. Future research prospects in multi-robot path planning based on probabilistic approaches are also discussed. 相似文献
5.
Polysilane supported dendrimer was efficiently utilized as an organocatalyst for Knoevenagel condensation reaction. Polysilane support was synthesized by the polymerization of trichloromethylsilane. The polypropyleneimine (PPI) dendrimer was grafted on the polymer support by divergent method. The dendrimer was synthesized up to three generations (G3). The dendrimer functionalized polysilane (PS‐PPIG3) was found to contain high concentration of terminal amino groups. The catalytic activity of the PS‐PPIG3 dendrimer was generalized by conducting the Knoevenagel condensation reaction with diverse sets of substrates, and was found to be an efficient organocatalyst. The condensation product could be easily separated from the reaction medium because of the heterogeneous nature of the polymer support. The reaction conditions were optimized, and the catalyst was found to be reusable. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41593. 相似文献
6.
An efficient and compact catalytic membrane reactor for reforming of CH4 was developed by integrating a hydrogen perm-selective silica membrane with an Rh/-Al2O3 catalyst layer. The catalytic layer was sandwiched between the outer surface of the -Al2O3 support tube and the silica membrane with an aim of improving the heat and mass transfer rates through the system and to simplify the reactor geometry. The system showed improved efficiency for reforming of CH4 at comparatively lower operating temperatures and steam to C molar ratios than the conventional fixed-bed steam reforming systems. Under optimized conditions, a nearly 25-30% improvement from the equilibrium conversion level was achieved as a result of abstraction of hydrogen from the product stream by the silica membrane integrated with the catalyst layer. The performance of the system was evaluated as a function of various process parameters. Because of the compactness and efficiency, the present system emerges as a promising alternative to the conventional membrane reactors, which possess separate catalytic and membrane units. 相似文献
7.
Cadmium-plated 0.35C–3.5Ni–1.5Cr–0.5Mo steel threaded fasteners of 1230 MPa properties class are used for aerospace applications.
These fasteners were torqued to 13 N·m. Few fasteners parted into two pieces while in use under sustained assembly load for
a period of 50 days. The fracture surface of the failed fasteners had two distinct regions when viewed under microscope at
higher magnification. Fractography revealed that the larger region consisted of predominantly intergranular features, whereas
the smaller region had features of microvoid coalescence. From the metallography evidences it was concluded that the fastener
failure was due to hydrogen embrittlement. Electro-deposit of cadmium was identified to be the main source for hydrogen entrapment,
which could not be compelled completely by post-plating baking treatment. 相似文献
8.
High strain rate deformation and cracking of AA 2219 aluminium alloy welded propellant tank 总被引:1,自引:0,他引:1
Abhay K. Jha S.V.S.N. Murty K. Sreekumar P.P. Sinha 《Engineering Failure Analysis》2009,16(7):2209-2216
Aluminium alloy AA 2219 (Al–6.6Cu–1Mn) is the candidate material for the fabrication of propellant storage tank of launch vehicle. Cold rolled sheets of 6.5 mm thickness are used to make the cylindrical shell, while sheets of 4.5 mm thickness are used for the construction of dome through petal forming technique. Petals, formed through cone rolling, treated to T87 temper condition are welded together by TIG welding to configure the dome. Such domes are joined to the cylindrical shell through a ring by TIG welding.The upper stage consists of two tanks, one oxidizer tank (liq. O2) and other fuel tank (liq. H2). After completing various developmental qualification tests, propellant flow rate test of one of the system was carried out. Almost all the liquid oxygen of the tank was removed and only a little quantity remained at the bottom. During one of the subsequent tests; when dry nitrogen gas was purged to evaporate the remaining liquid oxygen, the oxidizer tank dome catastrophically fractured with an audible sound. Fracture of oxidizer tank dome, placed at lower part of the system caused excessive deformation and subsequently it also caused fracture of fuel tank dome placed just over it.Detailed metallurgical investigations were carried out on the failed components and it was found that the tank failed under very high strain rate deformation. This paper brings out the details of the investigation carried out. 相似文献
9.
P.A. Sreekumar Selvin P. Thomas Jean marc Saiter Kuruvilla Joseph G. Unnikrishnan Sabu Thomas 《Composites Part A》2009,40(11):1777-1784
Sisal fibers were subjected to various chemical and physical modifications such as mercerization, heating at 100 °C, permanganate treatment, benzoylation and silanization to improve the interfacial bonding with matrix. Composites were prepared by these fibers as reinforcement, using resin transfer molding (RTM). The mechanical properties such as tensile, flexural and impact strength were examined. Mercerized fiber-reinforced composites showed 36% of increase in tensile strength and 53% in Young’s modulus while the permanganate treated fiber-reinforced composites performed 25% increase in flexural strength. However, in the case of impact strength, the treatment has been found to cause a reduction. The water absorption study of these composites at different temperature revealed that it is less for the treated fiber-reinforced composites at all temperatures compared to the untreated one. SEM studies have been used to complement the results emanated from the evaluation of mechanical properties. 相似文献
10.
A new polymer matrix sensitized with methylene blue for use as an optical recording material is described here. The characterization is done to determine the optimal recording conditions. These films need no chemical development and are found to be stable for several months. The matrix has excellent shelf life and needs an exposure only as short as 20 s. Direct imaging was done on this material. 相似文献