This paper reports the results of an experimental work conducted to investigate the effect of curing conditions on the compressive strength of self-compacting geopolymer concrete prepared by using fly ash as base material and combination of sodium hydroxide and sodium silicate as alkaline activator. The experiments were conducted by varying the curing time and curing temperature in the range of...

AIM The aim of this study was to measure the temperature increase induced by various light-curing units during photo-polymerization beneath ceramic restorations. METHODS Three light-curing units were used; a high intensity QTH unit Elipar 2500 and two LED units: Translux Power Blue and Excelled 1400. The 15 ceramic specimens (CEREC Blocks) used in this study were of 2.5 mm thickness, 5 mm wid...

PURPOSE To evaluate the depth of cure and surface hardness of two resin composites when subjected to three preheating temperatures, three polymerization times and two types of curing lights. METHODS Two resin composites were used in this study (Esthet-X and TPH), three polymerization times (10, 20, 40 seconds), three preheating temperatures (70, 100, 140 degrees F/21.1, 37.7 and 60 degrees C)...

The construction season is limited in northern countries due to the severe cold weather conditions and their detrimental impacts on concrete quality. Thus, there are excessive expenses required annually for insulation energy-intensive heating systems cold-weather concreting. This experimental study aimed investigate potential of using high-strength one-part alkali-activated blast furnace slag (...

OBJECTIVES Excessive heat produced during the curing of light-activated dental restorations may injure the dental pulp. The maximum temperature excursion at the pulp-dentin junction provides a means to assess the risk of thermal injury. In this investigation we develop and evaluate a model to simulate temperature increases during light-curing of dental restorations and use it to investigate the...

The effect of pre-heating resin composite on pre-cured viscosity and post-cured surface hardness was evaluated. Groups of uncured specimens were heated to 60 degrees C and compared with control groups (24 degrees C) with respect to viscosity and surface hardness. Mean (SD) viscosities of the pre-heated specimens (n = 15) were in the range of 285 (13)-377 (11) (Pa) compared with 642 (35)-800 (23...

In the petroleum industry, one of the most serious problems encountered during cementing is the failure at the bonding interface. Many measures including casing-sand adhesion have been developed to improve cementing bond strength. However, due to the lack of detailed study of the technique, many questions remain. The primary goal of this study is to investigate the influence of casing-sand adhe...

the cross-coupling reaction between phenylboronic acid and various types of aryl halides (suzuki reaction) was carried out using a catalytic amount of a new palladium catalyst (1-benzyl-3-(1-benzyl-1-methylpyrrolidin-1-ium-2-yl) pyridin-1-ium palladium chloride [dbnt][pdcl4]) in poly (ethylene glycol) (peg-200) in the presence of koh as the base. this new catalyst was synthesized and characteri...

Optical fibers are drawn with resin coatings that protect the glass. In general UV-curable resins are used for the coatings, and in most single-mode (SM) fibers a dualcoating structure is adopted. Each coating layer has an independent function in the protection of the glass. The coating in direct contact with the glass is known as the primary (P) coating, with the role of acting as a buffer aga...