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Material Increase (material + increase)

Distribution by Scientific Domains

Polymers and Materials Science	50%

Selected Abstracts

Ionic elastomers based on carboxylated nitrile rubber and magnesium oxide

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007
L. Ibarra
Abstract The crosslinking of carboxylated nitrile rubber (XNBR) with magnesium oxide (MgO) leads to an ionic elastomer with thermoplastic nature and better physical properties than the ones obtained with other metallic oxides. The crosslinking reaction leads to the formation of a metallic salt as unique product, as it could be seen on the ATR analysis of the samples, prepared at different reaction times. The mechanical properties of the material increase with the amount of crosslinking agent and segregation of an ionic microphase takes place. The presence of this microphase is demonstrated by a relaxation at high temperatures. The apparent activation energy of this relaxation is smaller than the activation energy of the glass transition of the elastomer, the former being more dependent on the amount of metallic oxide than is the latter. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1894,1899, 2007 [source]

Use of postmenopausal hormone therapy since the Women's Health Initiative findings,

PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 12 2005
Judith Parsells Kelly MS
Abstract Purpose To assess how use of postmenopausal hormone therapy (PHT) has changed since the Women's Health Initiative (WHI) trial was halted early due to an excess risk of stroke and other adverse outcomes. To estimate whether use of alternative drugs to treat menopausal symptoms (e.g., selective serotonin reuptake inhibitors [SSRIs], soy) has increased. Methods Women were interviewed in the Slone Survey, a random-digit-dial (RDD) survey of current medication use in a representative national sample. Information was obtained on PHT including dose, route, and reason for use, and on use of alternative drugs to treat menopausal symptoms. There were 3853 women aged ,50 years, interviewed from 1/2001 to 6/2004. Results The average weekly prevalence of PHT declined 57%, from 28% in the first half of 2002 to 12% in the first half of 2004. Use declined for conjugated estrogens (CE) and for other estrogens, taken either alone or with progestin. The decrease exceeded 50% in most strata of age, race, education, and region. The proportion of PHT users taking 0.3 mg CE did not change. Comparing prevalence in 2004 with prevalence in 2002, there was no material increase in use of black cohosh (2.0% in 2004) or soy (2.0%) and use of SSRIs was somewhat lower (8.9%). Conclusions These population-based usage data demonstrate a large decline in PHT use among women of postmenopausal age. The proportion of CE users taking lower doses has not increased. On a population basis, millions fewer women are using PHT in 2004 than before the WHI results were published, but there has been no appreciable increase in use of alternative therapies for menopausal symptoms over the same period. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Selective Zinc(II)-Ion Fluorescence Sensing by a Functionalized Mesoporous Material Covalently Grafted with a Fluorescent Chromophore and Consequent Biological Applications

ADVANCED FUNCTIONAL MATERIALS, Issue 2 2009
Krishanu Sarkar
Abstract A highly ordered 2D-hexagonal mesoporous silica material is functionalized with 3-aminopropyltriethoxysilane. This organically modified mesoporous material is grafted with a dialdehyde fluorescent chromophore, 4-methyl-2,6-diformyl phenol. Powder X-ray diffraction, transmission electron microscopy, N2 sorption, Fourier transform infrared spectroscopy, and UV-visible absorption and emission have been employed to characterize the material. This material shows excellent selective Zn2+ sensing, which is due to the fluorophore moiety present at its surface. Fluorescence measurements reveal that the emission intensity of the Zn2+ -bound mesoporous material increases significantly upon addition of various concentrations of Zn2+, while the introduction of other biologically relevant (Ca2+, Mg2+, Na+, and K+) and environmentally hazardous transition-metal ions results in either unchanged or weakened intensity. The enhancement of fluorescence is attributed to the strong covalent binding of Zn2+, evident from the large binding constant value (0.87,×,104M,1). Thus, this functionalized mesoporous material grafted with the fluorescent chromophore could monitor or recognize Zn2+ from a mixture of ions that contains Zn2+ even in trace amounts and can be considered as a selective fluorescent probe. We have examined the application of this mesoporous zinc(II) sensor to cultured living cells (A375 human melanoma and human cervical cancer cell, HeLa) by fluorescence microscopy. [source]

Impact of dilute acid pretreatment on the structure of bagasse for bioethanol production

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2010
Wei-Hsin Chen
Abstract Dilute acid pretreatment is a commonly used pretreatment method in the course of producing bioethanol from lignocellulosics and the structure variation of the lignocellulosics is highly related to the pretreatment process. To understand the impact of dilute acid pretreatment on the structure of bagasse, four different pretreatment conditions by varying heating time are considered where the bagasse and the pretreated materials are examined using a variety of analysis methods. The obtained results indicate that the thermogravimetric analysis (TGA) is able to provide a useful insight into the recognition of lignocellulosic structure. Specifically, the peak of the TGA of the pretreated materials moves toward the low temperature region, revealing that the lignocellulosic structure is loosened. However, the characteristic of crystal structure of cellulose remains in the pretreated materials. Increasing heating time enhances the pretreatment procedure; as a result, the average particle size of the investigated materials increases with heating time. This swelling behavior may be attributed to the enlarged holes inside the particles in that the surface area decreases with increasing heating time. In addition, when the heating time is increased to a certain extent (e.g. 15,min), some fragments are found at the surface and they tend to peel off from the surface. It follows that the dilute acid pretreatments have a significant effect on the bagasse structure. Copyright © 2009 John Wiley & Sons, Ltd. [source]