Structure of PPTA fibers derived directly from a liquid crystalline prepolymer dope in an organic solvent

The structure and properties of the pulp-like aromatic polyamide PPTA fibers prepared directly from a polymerization medium were studied by scanning electron microscopy (SEM), X-ray diffractometry, and polarizing light microscopy. The morphology of the fiber appears significantly different from that of Kevlar and does not reveal a skin-core structure. Regular defect bands and, thus, the regular clustering of the chain ends also could not be observed.     

Lubrication for Micro Forming of Ultra Thin Metal Foil

The objective of the present investigation is to establish lubrication technique in micro forming operation. Conventional lubricant, in general, cannot be applied directly to micro forming process, since the lubricant thickness is similar to the dimensions of feature size in micro forming operations. In present investigation, the Octadecyltrichlorosilane (OTS) self-assembled monolayer (SAM) was chosen as a potential lubricant because it sticks to Si wafer die and can be applied to surface with uniform thickness of several nanometer thick. Friction coefficient and adhesion force were measured for OTS SAM coated wafer. It is shown that OTS SAM coated Si wafer offers substantially lower friction and lower adhesion than bare Si wafer. Micro channel wafer die was coated with OTS SAM and channel forming operation with 1μm thick copper foil was carried out. Experimental results show that OTS SAM coated wafer die improves forming characteristic of ultra thin copper foil substantially. These results show that SAM coating can be used as a lubricant in micro forming successfully.     

MRI in presumed cervical anterior spinal artery territory infarcts

20 pairs of sera from the National System of Seroepidemiological Surveillance of the triple viral vaccine received in the laboratory with febrile rash diagnosis were studied. By using the hemagglutination inhibition test, it was observed an abnormal answer of antibodies to both rubella and measles through a falling of the antibody titre in one or both diseases, or in one of them with seroconversion to the other one. With the aim of defining the existence of a possible polyclonal activation already described in literature, it was decided to study the antibody response to family Herpesviridae (HSV, EBV, CMV, VZV). 80% of answer to these viruses were found. The results are submitted and discussed.     

Burr formation during micro via-hole punching process of ceramic and PET double layer sheet

Nowadays, recent electronic equipments are becoming smaller, multi-functional, and more complex. Similarly, low temperature co-fired ceramic (LTCC) has been emerged as a promising technology in the packaging industry. It consists of a multi-layer ceramic sheet, and a three-dimensional circuit. The via hole formation in LTCC plays an important role in providing an electric path for the interconnection between circuits. Therefore, via hole quality has a very important role for ensuring the performance of LTCC product. Via holes are formed on the green sheet that consists of ceramic (before sintering) layer and PET (Polyethylene terephthalate) layer. In this paper, we will discuss about the correlation between hole quality and process condition such as ceramic thickness, tool size, etc. The shear behavior of double layer sheet by micro hole punching which is different from that of single layer one will also be discussed.     

Large Charged Drop Levitation Against Gravity

A hybrid electrostatic-acoustic levitator that can levitate and manipulate a large liquid drop in one gravity is presented. To the authors' knowledge, this is the first time such large drops (up to 4 mm in diameter in the case of water) have been levitated against 1-gravity. This makes possible, for the first time, many new experiments both in space and in ground-based laboratories, such as 1) supercooling and superheating, 2) containerless crystal growth from various salt solutions or melts, 3) drop dynamics of oscillating or rotating liquid drops, 4) drop evaporation and Rayleigh bursting, and 5) containerless material processing in space. The digital control system, liquid drop launch process, principles of electrode design, and design of a multipurpose room temperature levitation chamber are described. Preliminary results that demonstrate drop oscillation and rotation, and crystal growth from supersaturated salt solutions are presented.     

Phase-controlled synthesis of thermally stable nitrogen-doped carbon supported iron catalysts for highly efficient Fischer-Tropsch synthesis

Nano Research - Iron-based nanoparticles with uniform and high particle dispersion, which are supported on carbon structures, have been used for various applications. However, their preparation...     

Preparation of turmeric-derived sulfur-functionalized carbon dots: antibacterial and antioxidant activity

Journal of Materials Science - The work describes the preparation of carbon dots using turmeric as the carbon source and their functionalization with sulfur to enhance the functionality. The...     

Development of thin‐film composite membranes for carbon dioxide and methane separation using sulfonated poly(phenylene oxide)

Novel membranes based on sulfonated poly (phenylene oxide) (SPPO) was developed. SPPO membranes in the hydrogen form were converted to metal ion forms. The effect of exchange with metal ions including monovalent (Li⁺, Na⁺, K⁺), divalent (Mg²⁺, Ba²⁺, Ca²⁺) and trivalent (Al³⁺) ions was investigated in terms of permeation rate and permeation rate ratios for CO₂ and CH₄ gases. Both dense homogeneous membranes and thin‐film composite (TFC) membranes were studied for their gas separation characteristics. The effect of membrane preparation conditions and operating parameters on the membrane performance were also investigated. The selectivity of the TFC membrane increased as the cationic charge density increased as a result of electrostatic cross‐linking. TFC membrane of very high selectivity was achieved by coating a thin layer of SPPO‐Mg on a PES substrate. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 735–742, 2000