Polymer, Metal, and Ceramic Microtubes by Strain-driven Self-rolling

A thin polymer bilayer film was transformed into micro- and nano-tubes using strain driven self-rolling phenomena of polystyrene (PS)/poly (4-vinyl pyridine) (P4VP) film. Polymer bilayer was produced by consecutive deposition of PS and P4VP, from toluene and chloroform solutions, respectively, by dip-coating technique. The object formation proceeds from a opening in the film made by photolithography or by mechanical scratching followed by immersion of patterned sample in dodecylbenzene sulfonic acid (DBSA) solution. DBSA forms supramolecular complexes with pyridine rings of P4VP and increases the specific volume of the polymer. Since the solution is neutral to PS layer, bilayer film develops strain due to unequal swelling of polymers in solution of DBSA and hence the film bends and scrolls in order to minimize its free energy and form tubes. The length of the tubes and the direction of rolling are determined by mechanical patterning of the film. UV-photolithography is used to fabricate patterns of polymer bilayer in order to create tube in a precise manner. The kinetics of the tube formation was studied with respect to acidity of the solution and UV dose. Rate of rolling increased with the acidity of the solution. Tube diameter and rate of rolling decreased with the increase of the UV exposure time. Films with 2-dimensional gradients of layer thicknesses were prepared to study a broad range of parameters in a single experiment. Furthermore, polymer micro-toroids and triangles were also fabricated using self-rolling approach of PS/P4VP layer. Moreover, the kinetics of toroid formation is also studied in the present work. The equilibrium dimensions of toroid are determined by the balance of the bending and the stretching energies of the film. The width of the rolled-up bilayer is larger for the films with higher values of the bending modulus and smaller values of the effective stretching modulus. Moreover, self-rolling phenomena of polymer layer was also explored as a template to fabricate metal, ceramic and metal/ceramic hybrid tube. In order to fabricate metallic and V bimetallic tube, the cross-linked polymer film is capped by metallic layer. After rolling, polymer template is removed by pyrolysis resulting in pure metal microtubes. The fabrication of silica and silica/gold hybrid tubes of high aspect ratio is also demonstrated. Polydimethylsiloxane (PDMS) is used as a precursor of the silica and it is converted into silica by pyrolysis at high temperature. Entire polymer moiety is also removed at this temperature. In order to fabricate hybrid tube of silica with gold, a thin gold layer is deposited on the polymer layer by physical vapour deposition. Self-rolling of polymer bilayers is a very convenient approach for interfacing the interior of microtubes with external electrical circuits and it can be used in particular for creating devices as micro-bubble generators exploiting electrolytic decomposition of fluids. A demonstration of microbubble generation inside the polymer tube is shown in this work. Possibility to functionalize the hidden walls of the tubes is one of the major advantages of the self-rolling approach. One can modify the surface of the film prior to rolling by magnetron sputtering of metal and upon rolling, tube and toroids with metallized inner surface could be obtained. The tube and toroids with metallic inner surface are promising for the future research as IR-frequency range resonators. Polymer and metallic microtubes fabricated by self-rolling approach may find applications in such fields as IR-waveguiding, microfluidics, enzyme bi-reaction, chemical and biochemical sensing. The silica and silica/gold hybrid tubes have potential use in optoelectronic devices and in catalytic applications

Behaviour of Market Arrivals and Prices of Selected Vegetable Crops: A Study of Four Metropolitan Markets

This study has been undertaken with the twin objectives of examining the variability pattern of market arrivals and prices of selected vegetable crops (cabbage, cauliflower, tomato and peas) in metropolitan markets of Delhi, Mumbai, Bangalore and Kolkata and analysing the relationship between market arrivals and prices. The study is based on market arrivals and wholesale prices of different vegetable crops collected from the Azadpur market of Delhi and Agricultural and Processed Food Products Export Development Authority (APEDA), New Delhi, for the period 1990-2001. The study has shown that the extent of variability in the arrivals of cabbage was lower in Bangalore and higher in Mumbai. The prices were relatively stable in Mumbai but were more volatile in Bangalore. There was broadly a similar pattern in the price variability across different months in Kolkata and Delhi markets. For cauliflower, the variability in the market arrivals was more pronounced in Kolkata than the remaining three markets. The price variability was, however, more marked in Delhi. The extent of variability in the market arrivals of tomato across different months was very high in all the four markets. Likewise, while the maximum variability in the prices of peas was noted for Delhi, these were relatively less marked in Bangalore. The results of the study have confirmed the negative relationship between market arrivals and prices in terms of correlation coefficients over the years and across months in all the four metropolitan markets, though there were several instances of positive relationship.Agricultural and Food Policy,

At the outset

I feel a strong need for a journal on Psychiatric Social Work, I don't think I need to justify why? The strongest reason isthe current development in Psychiatric Social Work (PSW) teaching and training institutions and rapid growth in researchand publication; where hundreds of journals are now coming up. I explored the various options and I was set to start anewthe journal, but then the name of the 'Indian Journal of Psychiatric Social Work' came in my mind which was started by Dr. R.K. Upadhayay, then the head Department of Psychiatric Social Work and publishing from Central Institute ofPsychiatry, Ranch. The first volume was published in 1972 and was in regular publication till 1978, volumeVIIwaswas lastthen discontinued many eminent faculty professionals have written paper for this journal and it was indexed inPsychological Abstracts, USA. Finally, I came into contact with Dr. R.K. Upadhayaywhich I was trying for two yearsand he graciously granted me permission to continue the Indian Journal of Psychiatric SocialWorkfromnext volume. Sothis is the story behind this journal which is now in your hand

Psychosocial Intervention Needs and Psychiatric Social Work Practice

From the very beginning of Social Work, human needs have long been part of social work theory, practice and research as an implicit conceptual foundation but practically it has long been a neglected and contested concept in the published literature of social work though social work has been instrumental in meeting the various needs of individuals. Social Work Practice in the field of mental health is also not an exception for the same. The need of an hour is to explicitly discuss the role of social work in meeting the human needs on the research and literature; the practice of which has already begun. It will have a significant influence on the contemporary practice of Psychiatric Social Work as well in India.         Keywords: Psychiatric social work, psychosocial intervention, need

Selection of Line Contingency for Power System Security Analysis

Contingency analysis (CA) has always been an in integral part of power system security analysis. CA is a useful tool at disposal of operation personnel to see effects of future outages on the system. The overload Performance Index (PI) is a good index for ranking the contingencies as per their severity. The PI requires “n” number of DC analysis to create a complete index, where n is no of lines. And for a larger network having a higher multitude of lines, it is time consuming. A new approach has been discussed for ranking the contingencies. This method requires one DC analysis and line outage distribution factor, which is constant for a particular unchanged transmission network

A Analysis of Different Type of Advance database System For Data Mining Based on Basic Factor

Normal databases are unable to handling such as large range and large amount of data. Then we need database to support creating, storage, indexing and retrieval of large and wide variety of data for mining. This research paper presents different ways of data mining for advance data as multimedia, spatial, Time-series and heterogeneous data and management of database is given to help to creating, storing, indexing and retrieval. This includes advanced data structures and use of metadata to store advance data like multimedia, spatial, Time-series and heterogeneous database. This research paper claim the database management systems should be extended to arrange new type of data and enable to search based on their contents. Media, Geometry, Time, Calendar objects and all type objects are modeled as attributes of abstract data types. This paper will be describe multimedia, spatial, time series and heterogeneous database as a point of data mining methods, database management technique, data type and application for advance database. DOI: 10.17762/ijritcc2321-8169.15020