A study of titanium thin films in transmission laser micro-joining of titanium-coated glass to polyimide

Electron beam evaporation (EB-PVD) and cathodic arc physical vapor deposition (CA-PVD) techniques were used for the preparation of titanium (Ti) thin films onto Pyrex borosilicate 7740 glass wafers and the deposited films were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) techniques. The microstructure and surface morphology of the films were studied as a function of the film deposition techniques. Film properties such as, adherence, microstructure and roughness were interconnected to the laser joint strength between Ti coated glass wafers and polyimide films. Ti thin films on glass had a natural oxide layer on the surface as found from XPS. AFM study showed the formation of a uniform Ti coating consisted of packed crystallites with average size of 35 nm by EB-PVD. The root-mean-square surface roughness of the films was 1-2 nm. Whereas, films prepared by CA-PVD had crystallites with an average size of 120 nm and defects in the form of macro-particles which is a common attribute of this deposition system. The surface roughness of the film was 125 nm. The laser joint strength was found to be influenced by the Ti film quality on the glass substrate.     

The grid protocol: a high performance scheme for maintainingreplicated data

A new protocol for maintaining replicated data that can provide both high data availability and low response time is presented. In the protocol, the nodes are organized in a logical grid. Existing protocols are designed primarily to achieve high availability by updating a large fraction of the copies, which provides some (although not significant) load sharing. In the new protocol, transaction processing is shared effectively among nodes storing copies of the data, and both the response time experienced by transactions and the system throughput are improved significantly. The authors analyze the availability of the new protocol and use simulation to study the effect of load sharing on the response time of transactions. They also compare the new protocol with a voting-based scheme     

Performance characterization of quorum-consensus algorithms forreplicated data

The authors develop a model and define performance measures for a replicated data system that makes use of a quorum-consensus algorithm to maintain consistency. They consider two measures: the proportion of successfully completed transactions in systems where a transaction aborts if data is not available, and the mean response time in systems where a transaction waits until data becomes available. Based on the model, the authors show that for some quorum assignment there is an optimal degree of replication beyond which performance degrades. There exist other quorum assignments which have no optimal degree of replication. The authors also derive optimal read and write quorums which maximize the proportion of successful transactions     

Laser fabrication and characterization of sub-millimeter joints between polyimide and Ti-coated borosilicate glass

Laser-fabricated joints of sub-millimeter widths between biocompatible, dissimilar materials have the potential for application as encapsulation of miniature implantable biomedical devices. In this work, we briefly describe the laser joining method of a very promising system, polyimide/titanium-coated borosilicate glass, and present results from characterization of such laser joints by means of mechanical failure (tensile) tests, optical and scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Our results suggest that the formation of the joints is a result of the creation of strong chemical bonds between Ti-containing species and certain polymeric functional groups. Mechanical tensile strength failure testing showed that such joints experience some degradation as a result of soaking in physiological solutions. This degradation is limited and, even after relatively long-term exposure the joints retain considerable strength.     

Multi-objective flower pollination algorithm: a new technique for EEG signal denoising

Neural Computing and Applications - The electroencephalogram (EEG) signal denoising problem has been considered a challenging task because of several artifact noises, such as eye blinking, eye...     

A comprehensive approach and methods for glacial lake outburst flood risk assessment,with examples from Nepal and the transboundary area

Like other mountainous areas, Nepal is highly vulnerable to glacial lake outburst floods (GLOFs), and this vulnerability has increased due to climate change. Risk reduction strategies must be based on a comprehensive risk assessment. A comprehensive methodological approach for GLOF risk assessment is described and illustrated in case studies of the potential GLOF risk posed in Nepal by four glacial lakes, one located in China. People, property and public infrastructure (including hydropower plants, roads and bridges) are vulnerable, and there is a need to integrate GLOF risk reduction strategies into national policies and programmes.     

Extension of fuzzy TOPSIS method based on interval-valued fuzzy sets

Decision making is one of the most complex administrative processes in management. In circumstances where the members of the decision making team are uncertain in determining and defining the decision making criteria, fuzzy theory provides a proper tool to encounter with such uncertainties. However, if decision makers cannot reach an agreement on the method of defining linguistic variables based on the fuzzy sets, the interval-valued fuzzy set theory can provide a more accurate modeling. In this paper the interval-valued fuzzy TOPSIS method is presented aiming at solving MCDM problems in which the weights of criteria are unequal, using interval-valued fuzzy sets concepts.     

Synthesis,characterization, and antimicrobial studies of newly developed metal‐chelated epoxy resins

A series of novel metal‐chelated epoxy resins have been synthesized by the condensation of epichlorohydrin (1‐chloro‐2, 3 epoxy propane) with bisphenolic metal chelates in alkaline medium. The bisphenolic chelates were initially prepared by the reaction of 3‐formyl‐4, 4′‐dihydroxy diphenyl methane and diamine (ethylenediamine/o‐phenylenediamine) in 1:2 molar ratio and then with Cu(II), Ni(II), and Co(II) acetate. The metal‐chelated epoxy resins were characterized by various instrumental techniques, such as elemental analysis, DSC and TGA, electronic, FTIR, ¹H‐NMR, and ¹³C‐NMR spectra. The physicochemical properties, viz., epoxide equivalent weight (eq/100 g), hydroxyl value (eq/100 g), refractive index, specific gravity, and specific viscosity were measured by standard procedures. The antimicrobial activities of these chelated resins were screened against Escherichia coli, Staphylococcus aureus, Bacillius subtilis (bacteria), and Candida albicans, Mucor species (yeast) by using agar well diffusion method. All the polymeric chelates show promising antimicrobial activities. Among these polymeric chelates (ERPD)‐Cu(II) shows better antimicrobial activities, which can be attributed to higher stability constant of Cu(II) chelate than others. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1347–1355, 2006     

Ultrahigh Gain Polymer Photodetectors with Spectral Response from UV to Near‐Infrared Using ZnO Nanoparticles as Anode Interfacial Layer

Significant increase of photocurrent upon UV light exposure is demonstrated in a narrow‐bandgap polymer‐based photodetector using ZnO nanoparticles as anode interfacial layer. The phenomenon is attributed to the UV light illumination induced oxygen molecules desorption from surface of ZnO nanoparticles, which reduces the electron injection barrier at the anode interface. Ultrahigh external quantum efficiency of 140 000% and extremely low gain threshold voltage of 1.5 mV are achieved in this device with 30 s UV light irradiation. The gain mechanism is explained by the fast transit and replenishment of photogenerated electrons within their lifetime, which is prolonged by the electron‐only device structure, and the experiment results fit well with the proposed photoconductive model.     

Designed Patterning of Mesoporous Metal Films Based on Electrochemical Micelle Assembly Combined with Lithographical Techniques

Mesoporous noble metals and their patterning techniques for obtaining unique patterned structures are highly attractive for electrocatalysis, photocatalysis, and optoelectronics device applications owing to their expedient properties such as high level of exposed active locations, cascade electrocatalytic sites, and large surface area. However, patterning techniques for mesoporous substrates are still limited to metal oxide and silica films, although there is growing demand for developing techniques related to patterning mesoporous metals. In this study, the first demonstration of mesoporous metal films on patterned gold (Au) substrates, prefabricated using photolithographic techniques, is reported. First, different growth rates of mesoporous Au metal films on patterned Au substrates are demonstrated by varying deposition times and voltages. In addition, mesoporous Au films are also fabricated on various patterns of Au substrates including stripe and mesh lines. An alternative fabrication method using a photoresist insulating mask also yields growth of mesoporous Au within the patterning. Moreover, patterned mesoporous films of palladium (Pd) and palladium–copper alloy (PdCu) are demonstrated on the same types of substrates to show versatility of this method. Patterned mesoporous Au films (PMGFs) show higher electrochemically active surface area (ECSA) and higher sensitivity toward glucose oxidation than nonpatterned mesoporous Au films (NMGF).