Drying Step (drying + step)

Distribution by Scientific Domains

Selected Abstracts

Direct Dentin Bonding Technique Sensitivity When Using Air/Suction Drying Steps

ABSTRACT Statement of Problem:, Moisture control before and after application of the primer/adhesive components of etch-and-rinse dentin bonding agents is usually achieved using a stream of air delivered by an air syringe. Suction drying with a suction tip is a common alternative for moisture control, but data about the use of suction drying instead of the air syringe is scarce or nonexistent. Purpose:, The purpose of this study was to compare the dentin microtensile bond strength (MTBS) using either the air syringe or the suction tip to control the amount of moisture. Materials and Methods:, Fifteen freshly extracted human molars were divided randomly into three groups of five. A three-step etch-and-rinse dentin bonding agent (OptiBond FL) was used. Group 1 was the control group and utilized air drying alone (with an air syringe) during the placement of the dentin adhesive on the ground-flat occlusal dentin surface. Group 2 also used air drying alone, but teeth were prepared with a standardized MOD cavity. Group 3 utilized suction drying alone in the standardized MOD cavity. All teeth were restored with 1.5-mm-thick horizontal increments of composite resin (Filtek Z100). Specimens were stored in water for 24 hours, then prepared for a nontrimming MTBS test. Bond strength data were analyzed with a Kruskal,Wallis test at p < 0.05. Specimens were also evaluated for mode of fracture and interface characterization using scanning electron microscope (SEM) analysis. Results:, The mean MTBSs were not statistically different from one another (p = 0.54) at 54.0 MPa (air-drying, flat dentin), 53.4 MPa (air-drying, MOD), and 49.2 MPa (suction drying, MOD). Microscopic evaluation of failure modes indicated that most failures were interfacial. Failed interfaces, when analyzed under SEM, appeared typically mixed with areas of failed adhesive resin and areas of cohesively failed dentin. Conclusions:, There are no differences in MTBS to human dentin using either the air syringe or the suction tip to control the amount of moisture. The conventional three-step dentin bonding agent used in the present study not only proved insensitive to the moisture-control method but also to the effect of increased polymerization shrinkage stress (ground-flat versus MOD preparation). CLINICAL SIGNIFICANCE Although the effect of common errors on the performance of total-etch adhesives has been investigated, data about the use of suction drying instead of an air syringe is scarce or nonexistent. The present study demonstrated that both the air syringe and the suction tip can be used to control moisture when using etch-and-rinse dentin bonding agents. The conventional three-step dentin bonding agent tested, OptiBond FL, demonstrated low technique sensitivity. [source]

Flux enhancement in TFC RO membranes

Mark A. Kuehne
The effects of varying processing conditions during fabrication of TFC RO membranes were systematically investigated. It was found that the membrane flux is greatly dependent on the processing steps that follow the synthesis of the thin film coating, such as washing, treatment with glycerol, and drying of the membrane. Glycerol is not simply a passive flux - p reserving agent, preventing loss of porosity during oven drying. In combination with a second oven drying step, glycerol actively enhances flux. Membrane flux can be similarly enhanced by treatment with solutions of organic salts, followed by oven drying. The effect of these treatments is quite large, increasing the flux by 30,70%, with no loss of salt rejection. Flux-enhancing additives were also used in the aqueous polyamine solution used to prepare the thin film coating. [source]

Evaluation of the use of dried spots and of different storage conditions of plasma for HIV-1 RNA quantification

HIV MEDICINE, Issue 6 2007
B Amellal
Objectives The aim of the study was to evaluate the use of dried plasma spots to determine HIV-1 RNA viral loads. Methods The viral loads of 30 liquid plasma samples were compared with those of corresponding dried plasma spots on filter paper (DPS-FP) and in tubes (DPS-T), both of which were left for 7 days at 22C. Also, 10 liquid plasma samples with detectable viral load were stored at 4, 22 or 37C for 7 days and five further liquid plasma samples were air-dried for up to 54 h to assess the effects of temperature and the drying step on HIV-1 viral load. Results The viral loads of the 30 liquid plasma samples correlated significantly with those of the paired dried spots DPS-FP and DPS-T, but with median losses of 0.64 and 0.69 log10 HIV-1 RNA copies/mL, respectively, and a limit of detection of 3 log10 copies/mL. The 10 liquid plasma samples stored for 1 week at 37C showed a weaker correlation and had a significantly reduced median viral load (,0.92 log10; P=0.005) when compared with the viral load of the matched plasma stored at ,80C. Most of the loss happened during the drying step. Conclusions Reliable measurement of HIV-1 RNA viral load requires good plasma storage conditions. HIV RNA stability was affected by desiccation and 1 week of storage at 37C. However, our findings suggest that liquid plasma can be kept at 4 or 22C for a week with no effect on viral load. [source]

Application of continual injection liquid-phase microextraction method coupled with liquid chromatography to the analysis of organophosphorus pesticides

Yanuardi Raharjo
Abstract A liquid-phase microextraction coupled with LC method has been developed for the determination of organophosphorus pesticides (methidation, quinalphos and profenofos) in drinking water samples. In this method, a small amount (3 ,L) of isooctane as the acceptor phase was introduced continually to fill-up the channel of a 1.5 cm polypropylene hollow fiber using a microsyringe while the hollow fiber was immersed in an aqueous donor solution. A portion of the acceptor phase (ca. 0.4 ,L) was first introduced into the hollow fiber and additional amounts (ca. 0.2 ,L) of the acceptor phase were introduced to replenish at intervals of 3 min until set end of extraction (40 min). After extraction, the acceptor phase was withdrawn and transferred into a 2 mL vial for a drying step prior to injection into a LC system. Parameters that affect the extraction efficiency were studied including the organic solvent, length of fiber, volume of acceptor and donor phase, stirring rate, extraction time, and effect of salting out. The proposed method provided good enrichment factors of up to 189.50, with RSD ranging from 0.10 to 0.29%, analyte recoveries of over 79.80% and good linearity ranging from 10.0 to 1.25 mg/L. The LOD ranged from 2.86 to 82.66 ,g/L. This method was applied successfully to the determination of organophosphorus pesticides in selected drinking water samples. [source]

Red Blood Cell Templated Polyelectrolyte Capsules: A Novel Vehicle for the Stable Encapsulation of DNA and Proteins

Oliver Kreft
Abstract Summary: A novel method for the encapsulation of biomacromolecules, such as nucleic acids and proteins, into polyelectrolyte microcapsules is described. Fluorescence-labelled double-stranded DNA and human serum albumin (HSA) are used as model substances for encapsulation in hollow microcapsules templated on human erythrocytes. The encapsulation procedure involves an intermediate drying step. The accumulation of DNA and HSA in the capsules is observed by confocal laser scanning microscopy, UV spectroscopy, and fluorimetry. The mechanism of encapsulation is discussed. Confocal fluorescence microscopy images of encapsulated TRITC-HSA (left) and dsDNA (right). Inserts demonstrate fluorescence profiles for both compounds. [source]

UV curing behaviors and hydrophilic characteristics of UV curable waterborne hyperbranched aliphatic polyesters,

Anila Asif
Abstract A series of waterborne hyperbranched polyesters (WBHPs) endcapped with methacrylic and salt-like groups in different ratios have been investigated as UV curable resins. The kinetic studies of the drying step and UV curing were carried out by FT-IR measurements. The drying of the film of 100,,m thickness was completed in less than 6,hr at 70C or within 10,hr at 50C in an oven. The influence of different photoinitiators and their concentrations, extent of unsaturation and acid content of WBHP on final unsaturation conversion was studied. The surface free energy is a critical character, which affects the surface properties of a cured film. So one method based on the measurement of contact angle of a pure liquid on a solid surface was applied to determine the polar and dispersive components of the surface energy of UV cured films. The investigations of surface energy of WBHPs illustrated that those with more acid content and thus higher polar component are more sensitive to water, while those containing less acid content and thus lower polar term are less water sensitive. Moreover, the UV cured films of WBHPs and their blends with commercial waterborne resins (trade name EB 210, EB 2002, EB 11 and IRR 160) have acceptable pendulum hardness varying from 55 to 180,sec. Copyright 2003 John Wiley & Sons, Ltd. [source]

Alkaline neutralization of crude soybean oil by various adsorbents

Sukran Kuleasan
Abstract The effect of sodium hydroxide in neutralization was increased by using various adsorbents. NaOH in various concentrations was attached to the particles of Kieselguhr, Celite and Bentonite. The neutralization reaction was performed at ambient temperature, and different reaction times were applied. The soap formed after reaction was removed by centrifugation; thus, washing and drying steps were omitted. The amount of remaining soap, the acidity and color of oils were determined after each treatment. According to the results, free fatty acid neutralization in crude oil was achieved by Kieselguhr application. In this process, 9.5% NaOH was applied for 60,min of reaction time. The free fatty acid content of crude oil was decreased from 0.56 to 0.14%, and the remaining soap was found at 34,mg/kg after centrifugation. The use of adsorbents increased the efficiency of NaOH in the neutralization reaction and in the removal of soap from the neutralized oil. Neutralization with support material is a new and promising approach. The application is energy saving, more practical and in accordance with the strict environmental legislation about waste disposal. [source]

COMMENTARY. direct dentin bonding technique sensitivity when using air/suction drying steps

David H. Pashley DMD