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Modified System (modified + system)

Distribution by Scientific Domains

Polymers and Materials Science	36%
Medical Sciences	36%

Selected Abstracts

Modification of bisphenol A dicyanate ester by carboxyl-terminated liquid butadiene-acrylonitrile and its composites

POLYMER ENGINEERING & SCIENCE, Issue 5 2006
Jieliang Wang
Cyanate esters with excellent high-temperature properties and easy processing are well known as good resin materials used in aerospace and electrical industries, but the drawback of brittleness limits their usage. In this study, carboxyl-terminated liquid butadiene-acrylonitrile (CTBN) was introduced to improve the toughness of bisphenol A dicyanate resin (BADCy), a typical kind of the cyanate esters. Fourier transform infrared spectroscopy and differential scanning calorimetry were employed to investigate the effects of CTBN on the curing behavior of BADCy; the results indicate that the addition of CTBN has a great influence on the curing behavior of BADCy at lower temperatures, but little at higher temperatures. Data from the thermogravimetric analysis and heat deflection temperature analysis showed that the thermal properties of the modified systems were poorer than that of pristine BADCy resin. On the basis of the scanning electron micrographs of the modified systems, toughening mechanism of the systems was discussed. Mechanical and dielectric properties of the cured resins and glass fiber-reinforced composites were also studied. Modified systems exhibit attractive properties for the future applications in aerospace industries. POLYM. ENG. SCI. 46:581,587, 2006. © 2006 Society of Plastics Engineers. [source]

Performance analysis of a modified two-bed solar-adsorption air-conditioning system

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2009
K. Sumathy
Abstract This paper presents the description and operation of a solar-powered modified two-bed adsorption air-conditioning system with activated carbon and methanol as the working pair. A simple lumped parameter model is established to investigate the performance of this continuous adsorption cycle consisting of a twin adsorber immersed in water tanks, which is measured in terms of the temperature histories, gross solar coefficient of performance and specific cooling power. In addition, the influence of some important design and operational parameters on the performance of the system has been studied. Compared with the conventional system, it is found that the modified system can operate more cycles and at a higher efficiency. The parametric study also shows that the adsorbent mass and the solar collector area have significant effect on the system performance as well as on the system size. Finally, when the system uses gas heater as an auxiliary heat source, it is found that the system can provide a stable cooling effect for a longer period of operation. Copyright © 2008 John Wiley & Sons, Ltd. [source]

The impact of portfolios on health professionals' practice: a literature review

INTERNATIONAL JOURNAL OF PHARMACY PRACTICE, Issue 6 2008
Andrzej Jerzy Kostrzewski senior principal pharmacist in education
Objectives The purpose of this paper is to review the literature on the use of a portfolio and discuss the evidence for the impact of a portfolio on professional practice, in particular pharmacy practice. Method A literature review was performed using databases from health care and education, namely AMED, BEI, CINAHL, Embase, ERIC, IPA, MedLine, PHARM-LINE, Psycinfo, TIMELIT and ZETOCs, as well as a manual search of relevant journals and documents between 1991 and 2007. The search terms included portfolio, progress files and assessment, and these were linked with pharmacy. Articles were included in the review if they had a focus on the portfolio as a contribution to professional practice. Key findings Portfolios have been used in the education field for over decade. A total of 26 out of 1901 papers were identified which examined portfolios in a post-registration setting. The majority of these publications were from medicine (12), with education (six), pharmacy (five) and nursing (three) making up a small proportion. Portfolios were seen as (a) a tool for use in feedback, (b) a useful trigger for reflection and (c) a link between academic learning and practice. A similar set of findings were seen in the educational context. In addition, a portfolio (a) requires motivation to record and (b) can change behaviour towards colleagues. Conclusions There is still confusion about the meaning of a professional portfolio in health care professions. It is suggested that portfolios should be classified according to a modified system from the teaching profession. The evidence that portfolios can contribute to practice is limited. This review suggests the need for more studies into the impact of portfolios on professional practice, in particular in a pharmacy context. [source]

Image enhancement in ultramicroscopy by improved laser light sheets

JOURNAL OF BIOPHOTONICS, Issue 10-11 2010
Saiedeh Saghafi
Abstract In the majority of implementations of light sheet microscopy, such as ultramicroscopy, the laser beam illuminating the specimen is truncated by a slit aperture before it is focused to a light sheet by a single cylindrical lens. A light sheet generated in this way can be made very thin near to the focal point, but unfortunately its Rayleigh range is severely limited. This problem can be partially solved by using a smaller slit aperture. However, this also causes a major loss in power, a severe broadening of the beam waist, and thus a significant loss of resolution along the detection axis. We developed improved light-sheet-generation optics, which provide longer Raleigh ranges, whilst retaining beam waists comparable to our standard system with one cylindrical lens. Using the modified system we achieved a marked improvement in the resolution of ultramicroscopy reconstructions of representative biological specimens. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Raman spectroscopy with simultaneous measurement of two orthogonally polarized Raman spectra

JOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2003
G. A. Thomson
Abstract A Raman microscope was modified to allow the independent acquisition of two orthogonally polarized components of a Raman spectrum in a single measurement. Preliminary performance was demonstrated by simultaneously measuring the intensity of both polarized components of the silicon Raman band at 520 cm,1 as a silicon wafer was rotated through 360° under a polarized laser Raman probe. Polarization-resolved Raman spectra of a complex molecular crystal are also presented, illustrating the increase in spectral information available with the modified system. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Patient-maintained propofol sedation: a follow-up safety study using a modified system in volunteers

ANAESTHESIA, Issue 4 2002
F. Henderson
Summary Patient-maintained sedation is a mode of patient-controlled sedation during which propofol is administered using a target-controlled infusion, with patient demand increasing the target concentration. A system tested previously for safety in our institution resulted in oversedation. Aiming to improve safety, we modified the system by increasing the lockout period to 4 min, reducing the starting concentration to 0.5 µg.ml,1 and the increments on demand to 0.1 µg.ml,1. As in the previous study, healthy volunteers attempted to render themselves unconscious by frequently pressing the demand button. To assess effects on memory, volunteers were given keywords to remember every 15 min. The maximum target concentration reached varied between 1.0 and 2.5 µg.ml,1. No volunteers lost consciousness, however, one volunteer had a brief period of apnoea and oxygen desaturation. The Cp50 for loss of memory for words was 1.26 µg.ml,1. Although this version represents an improvement, we conclude that the system is not yet completely suitable for use without anaesthetic supervision. [source]

Conceptualising a modified system for classification of in-hand manipulation

AUSTRALIAN OCCUPATIONAL THERAPY JOURNAL, Issue 1 2009
Karina Pont
Occupational therapists consider in-hand manipulation (IHM) to be an important component of fine motor skills and to be related to handwriting and self-care proficiency. These relationships have not been well explored nor has the impact of intervention including IHM skill enhancement on proficiency in motor tasks. We propose that the existing conceptualisation of IHM may contribute to a dearth of evidence in this area. This paper closely examines the existing classification systems of IHM. We propose an adaptation of Exner's classification system which contains more discrete categories of IHM movements and includes: finger-to-palm translation to achieve stabilisation, palm-to-finger translation, simple shift, complex shift, simple rotation and complex rotation. Further research to test this modified classified system and to explore evidence for IHM intervention is warranted. [source]

Phylogeny of the Eucoilinae (Hymenoptera: Cynipoidea: Figitidae)

CLADISTICS, Issue 2 2002
F.M. Fontal-Cazalla
The Eucoilinae are a diverse and important group of parasitoids of Diptera, particularly in the tropics, but they are poorly known systematically and their generic classification is partly chaotic. Here, we present the first comprehensive cladistic analysis of higher eucoiline relationships. The analysis is based on 148 skeletal characters of adults documented in more than 1100 digital images available in an Internet-accessible database. The characters were coded for 45 taxa representing 35 eucoiline genera, spanning the entire diversity of the group, and 7 outgroup genera. Relationships were partly difficult to resolve and parsimony analysis under implied weights performed considerably better than analysis under uniform weights. The results support the monophyly of the Eucoilinae and show that eucoilines are most closely related to the figitid subfamilies Emargininae and Pycnostigminae, but are ambiguous concerning the exact relationships among these three lineages. Of the 6 eucoiline genus groups recognized by Nordlander in 1982 (Entomol. Scand. 13, 269,292), only 2 are supported as monophyletic: the Trybliographa and Kleidotoma groups. The Gronotoma group is a paraphyletic assemblage of two different basal clades of eucoilines. The Rhoptromeris group is unnatural and only the 2 core genera, Rhoptromeris and Trichoplasta, form a monophyletic lineage. The data are ambiguous concerning the Ganaspis group, which appears to be paraphyletic, and the Chrestosema group, which may be a good clade. Based on the results we propose a modified system of informal genus groups in the Eucoilinae and discuss putative synapomorphies supporting each genus group. The proposed relationships imply that the first eucoilines were parasitoids of leaf-mining agromyzids. The earliest split in the group was apparently between an Afrotropical and a Neotropical lineage, and much of the early radiation of the group occurred in these regions, particularly in the Neotropics. [source]

Dielectric Properties of the Perovskite System Pb(Mg1/3Nb2/3)O3 -PbTiO3 Modified by Pb(Mg1/3Ta2/3)O3 and Pb(Zn1/3Nb2/3)O3

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2001
Dong-Hwan Suh
Effects of Pb(Mg1/3Ta2/3)O3 and Pb(Zn1/3Nb2/3)O3 substitution in the Pb(Mg1/3Nb2/3)O3 -PbTiO3 ceramic system on structure formation, crystallographic aspects, and dielectric properties are discussed. Developed phases in the B-site precursor and perovskite systems were studied by X-ray diffraction. Crystal symmetries and dimensions of the perovskite unit cell of the two systems are compared. Changing rates of the lattice parameter with substituent PbTiO3 concentration in the two modified systems are virtually identical to that of the unmodified Pb(Mg1/3Nb2/3)O3 -PbTiO3 system. Weak-field low-frequency dielectric responses of the ceramics were investigated. The dielectric maximum temperatures of the two perovskite systems shifted almost linearly with compositional change. Dielectric constant spectra at low concentrations of PbTiO3 exhibited typical diffuse phase transition behavior, whereas those at high PbTiO3 concentrations were rather sharp. The phase transition modes reflected on the dielectric spectra were quantitatively analyzed in terms of diffuseness parameters. [source]

In situ monitoring of reaction-induced phase separation with modulated temperature DSC

MACROMOLECULAR SYMPOSIA, Issue 1 2003
Steven Swier
Abstract A linearly polymerizing and network forming epoxy-amine system, DGEBA-aniline and DGEBA-MDA, respectively, will be modified with 20 wt% and 50 wt% of a high- Tg thermoplastic poly(ether sulphone) (Tg=223°C), respectively, both showing LCST-type demixing behavior. Reaction-induced phase separation (RIPS) in these modified systems is studied using Modulated Temperature DSC (MTDSC) as an in situ tool. Phase separation in the linear system can be probed by vitrification of the PES-rich phase, occurring at a higher conversion than the actual cloud point from light scattering measurements. The negative slope of the cloud point curve in a temperature-conversion-transformation diagram unambiguously shows the LCST-type demixing behavior of this system, while the relation between the composition/glass transition of the PES-rich phase and the cure temperature is responsible for the positive slope of its vitrification line. Phase separation in the network forming system appears as reactivity increases at the cloud point due to the concentration of reactive groups. Different mixture compositions alter the ratio between the rate of phase separation and the rate of reaction, greatly affecting the morphology. Information about this in situ developed structure can be obtained from the heat capacity evolutions in non-isothermal post-cures. [source]