objectives: this study aimed to compare the microleakage beneath metallic brackets following two different methods of enamel preparation and light curing. materials and methods: a total of 120 bovine deciduous lower incisors were randomly divided into four groups of 30 teeth. the preparations were as follows: group i: acid etching + transbond xt primer + direct illumination, group ii: acid etch...

in this paper, iron ore sample from the chadormalu was investigated to determine some comminution properties. chadormalu deposit is one of the largest iron ore mine in iran, which is located in yazd province. the representative ore sample contained 57%fe, 0.9%p and 0.17%s. the sample was crushed; afterward, it was ground in various grinding times according to the bond ball mill approach to spec...

background: agate is a hard silica stone with bands of various colors, which is used in jewelry. the agate grinding workers are exposed to silica dust. objective: to determine the prevalence of respiratory diseases in agate grinding workers and the associated factors. methods: in this cross-sectional study, 170 agate grinding workers from mashhad, northeastern iran, were examined. medical and o...

Aroma recovery as determined by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) was compared in coffees resulting from conventional grinding processes, and from wet grinding with cold and hot water. Freshly roasted coffee as well as old, completely degassed coffee was ground in order to estimate the relationship of internal carbon dioxide pressure in freshly roaste...

Background: The austenitic stainless steel 304L is widely used as a structural material for which the finished surface has significant effect on the service performance. A study of the grinding process with regard to the quality of the ground surfaces is therefore interesting from the point of view of both industrial application and scientific research. Method: This work investigates the influe...

objectives: this study aimed to evaluate the effect of chlorhexidine (chx) application protocol on durability of marginal seal of class v composite restorations. materials and methods: class v cavities (4×2×1.5mm) were prepared in the buccal surfaces of 160 human third molars. the teeth were randomly divided into five groups (n=32) of (g1) chx+rinse+etching, (g2) chx+etching, (g3) etching+chx+r...

Forces generated during precision wafer grinding are small and present challenges for accurate and reliable process monitoring. In this work, these challenges are met by incorporating noncontact displacement sensors into an aerostatic spindle that is calibrated to measure grinding forces from the relative motion between the spindle rotor and stator. This arrangement allows the calculation of gr...

in this project creep feed grinding process of gas turbine blade root is investigated with the aim of consistant and controlable production. inthispaper, effectiveness of creep feed grinding process prometers suchas wheel speed, workpiece speed, grind depth and dresser speed are investigated. this investigation include their interaction on thelob of gas torbine blade root, as amajor cause of a ...

objectives: this study aimed to assess the effect of re-etching of desensitized dentin for five and 10 seconds on marginal microleakage of composite restorations. materials and methods: class v cavities (4x2x2mm) were prepared on the buccal surfaces of 64 third molars and randomly divided into four groups of 16. in the control group, single bond (sb) adhesive was applied after etching. in bb+sb...

This paper describes an ultra precision polishing method of aspherical mirrors, and the fundamental research on polishing characteristics. The aspherical mirrors with a diameter of about 30mm made by fused silica glass and CVD-SiC were ELID (electrolytic in-process dressing)-ground to high form accuracy with #4000 cast iron bonded diamond wheel, and then polished with a small polishing tool. As...