Piezoelectric properties of PVDF-conjugated polymer nanofibers

This study presents the development and characterization of PVDF-conjugated polymer nanofiber-based systems. Five different conducting polymers (CPs) were synthesized successfully and used to create the nanofiber systems. The CPs used are polyaniline (PANI), polypyrrole (PPY), polyindole (PIN), polyanthranilic acid (PANA), and polycarbazole (PCZ). Nanofiber systems were produced utilizing the Forcespinning® technique. The nanofiber systems were developed by mechanical stretching. No electrical field or post-process poling was used in the nanofiber systems. The morphology, structure, electrochemical and piezoelectric performance was characterized. All of the nanofiber PVDF/CP systems displayed higher piezoelectric performance than the fine fiber PVDF systems. The PVDF/PPY nanofiber system displays the highest piezoelectric performance of 15.56 V. The piezoelectric performance of the PVDF/CP nanofiber systems favors potential for an attractive source of energy where highly flexible membranes could be used in power actuators, sensors and portable, and wireless devices to mention some.     

The efficiency of private and public schools in urban and rural areas: moving beyond the development goals

Data from the Young Lives study are used to evaluate the efficiency of education systems in four low and middle income countries: Ethiopia, India, Peru and Vietnam. A meta‐frontier variant of data envelopment analysis is used to assess the relative performance of each country's system, and, within each country, to evaluate the impact of public and private schooling, and of urban and rural location. Comparisons are drawn between the four countries; the results indicate that in no country does the educational system perform uniformly badly or well. Conditioning on the inputs available, rural areas are often indicative of higher levels of efficiency, thus suggesting a number of implications for policy.     

Effect of gamma irradiation on the optical properties of CR-39 polymer

The UV-Visible absorption spectra of virgin and gamma irradiated (20–800 kGy) CR-39 polymer have been deduced by using Shimadzu Double beam Double Monochromator UV-Visible Spectrophotometer (UV-2550). The existence of the peaks, their shifting and broadening as a result of gamma irradiation has been discussed. Finally the indirect and direct band gap in virgin and gamma irradiated CR-39 has been determined. The values of indirect band gap have been found to be lower than the corresponding values of direct band gap.     

Hybrid of multi-signal processing methods for detection of small objects in containers filled with beverages using ultrasound

Ultrasound backscattered signals for object detection could be too weak to be perceived when superposed to strong reflection signals, and could also be complicated either in time or frequency domain. These peculiarities raise a challenge for signal processing methods. In this paper four signal processing methods were studied to detect objects in containers. Root mean squares (RMS) method was better in object detection but needed to combine other methods to increase detection success rate. Variance, center frequency pressure ratio (CFPR) and backscattered amplitude integral (BAI) methods have similar overall detection ratings. The optimal signal size, to increase the detection ability, corresponded approximately to the length of reverberation signals before it was dissipated.     

Unified modeling technique for high-viscosity,melt-phase,condensation polymer reactors

Mathematical models for chemical reaction and mass transfer occurring in the manufacture of high-viscosity condensation polymers are considered. A preliminary study indicates that several diverse models can be represented using a single formula based upon an effectiveness factor. The effectiveness factor is shown to depend upon a ratio of time scales of mixing and reaction. The formula giving the effectiveness factor in terms of the time scales ratio is shown to depend upon mixing assumptions only. Starting with a mixing-cell model, a new modeling framework is developed and shown to include the previous models as special cases. The framework is free of inherent mixing assumptions and can be applied to a wide variety of situations once the mixing characteristics are specified. © 1993 John Wiley & Sons, Inc.     

Cornea stress test--evaluation of corneal endothelial function in vivo by contact lens induced stress

Changes in the NHS have supported the idea of targeting health services to those in greatest need. This has meant that health visitors are increasingly having to identify 'vulnerable' families in need of increased health visiting intervention. This paper reports on a qualitative study undertaken in order to explore the ways in which health visitors plan and organize their work in relation to the concept of vulnerability. Focus groups and semi-structured interviews were carried out with health visitors from two separate geographical areas, one an inner city area and the other suburban, in order to explore the criteria by which health visitors define vulnerability and decide to increase their levels of intervention to particular families. It was found that vulnerability was extremely difficult to define but that the health visitors used criteria which were appropriate to the particular localities in which they worked to identify vulnerable families and to increase their levels of intervention to those families. Health visitors were targeting their services within a framework of a basic minimum service to all and were assessing the health needs of individuals or families rather than planning their work on the basis of community or practice profiles.     

Microwave-Assisted Synthesis of Fine Particle Oxides Employing Wet Redox Mixtures

Interaction of electromagnetic radiation with a physical mixture of metal nitrates and amides/hydrazides is observed to initiate high-temperature reactions, useful for realizing several high-temperature ceramic materials. A judicious choice of such redox mixtures undergoes exothermic reactions when they couple with microwave radiation. The coupling of electromagnetic radiation with metal salts and amides/hydrazides depends on the dielectric properties of the individual components in the reaction mixture. The approach has been used to prepare γ-Fe₂O₃, Fe₃O₄, MgCr₂O₄, α-CaCr₂O₄, and La_0.7Ba_0.3MnO₃.     

Identification and characterization of genus-specific epitopes of Serpulina species using monoclonal antibodies

Four murine monoclonal antibodies (mAbs) designated as C9E8, A10, G12, and G8 which recognized both Serpulina hyodysenteriae and S. innocens were produced and characterized. The mAbs reacted with whole cell antigens in ELISA, indirect immunofluorescence and immunoblot assays. The mAbs did not show any cross reactivity in rapid dot ELISA or immunoblot assay with Leptospira icterohemorrhagiae, Campylobacter jejuni and Escherichia coli. Treatment of whole cell suspension with proteinase K and sodium periodate indicated that the reacting epitopes of the mAbs were protein in nature. The genus-specific antigens were identified as heat-stable proteins with molecular weight in the range of 26 to 45 kDa. Immunofluorescence and immunogold labelling studies showed that the antibody-binding epitopes were exposed on the outer-surface of the spirochaetal cell wall. The mAbs inhibited growth of reference strains of both S. hyodysenteriae and S. innocens in vitro but failed to cause agglutination. The detection of spirochaetal forms directly in fecal smears or paraffin-embeded tissue sections from experimentally infected pigs indicated that such mAbs were potentially useful for the diagnosis of swine spirochaetosis. This is the first report of mAbs identifying and characterizing common antigens of porcine Serpulina.     

Protective effect of Picroliv from Picrorhiza kurroa against Leishmania donovani infections in Mesocricetus auratus

The prevalent drugs for treatment of kala azar viz. sodium stibogluconate (SSG) and pentamidine cause severe toxic side effects and acute immunosuppression in the treated individuals. Picroliv, a standardized mixture of iridoid glycosides, prepared from the alcoholic extract of the root and rhizome of Picrorhiza kurroa has shown strong hepatoprotective activity against several models of hepatotoxicity. Therefore, the present study was undertaken with an objective to study the effects of Picroliv (12.5 mg/kg x 7 days oral) alone and in combination with SSG on parasitemia, lipid peroxidation and hepatic marker enzymes of golden hamsters during Leishmania donovani infection. The results indicated a marked hepatoprotective effect of Picroliv in terms of biochemical markers, and a significant antileishmanial activity implying that it can be utilized as an adjunct to chemotherapy or in combination therapy of kala azar along with sodium stibogluconate, thus enhancing the efficacy of antileishmanials.     

Favorable influence of ssDNA-functionalized SWCNT on the navigation pattern of C. elegans

Microsystem Technologies - Single-Walled Carbon Nanotubes (SWCNTs) are widely used as potential carriers in drug delivery systems. The objective of this work was to observe the effects of pristine,...