A modified dumbbell obtained by replacing one of the phenyl groups of the dibenzylammonium with a strong electron-withdrawing trifluoromethyl group templated the synthesis of the smallest [2]rotaxane reported so far. The trifluoromethyl group not only enhances the templating effect of the dumbbell but also acts as the stopper to prevent dethreading of a [20]crown ether macrocycle.

introduction the aim of this study was to compare the smear layer removal efficacies of 3% sodium hypochlorite (naocl), 17% ethylenediaminetetraacetic acid (edta), smearclear and biopure mtad using a common irrigation protocol. materials and methods: fifty freshly extracted human single rooted maxillary and mandibular teeth were prepared by a protaper rotary system up to an apical preparation f...

the effect of evaporation rate on structural, morphological and optical properties of electron beam evaporated cds thin films have been investigated. cds thin film deposited by electron beam evaporation method in 12nm/min and 60nm/min evaporation rates on glass substrates. x-ray diffraction, scanning electron microscopy, uv-vis-nir spectroscopy and atomic force microscopy were used to character...

In many bacterial viruses and in certain animal viruses, the double-stranded DNA genome enters and exits the capsid through a portal gatekeeper. We report a pseudoatomic structure of a complete portal system. The bacteriophage SPP1 gatekeeper is composed of dodecamers of the portal protein gp6, the adaptor gp15, and the stopper gp16. The solution structures of gp15 and gp16 were determined by N...

introduction: the aim of this in vitro study was to evaluate the effect of an experimental irrigation solution, containing two different concentrations of papain, tween 80, 2% chlorhexidine and edta, on removal of the smear layer. methods and materials: thirty-six single-rooted teeth were divided into two experimental groups ( n =12) and two positive and negative control groups of six. the cana...

introduction: smear layer (sl) is produced as a result of mechanical instrumentation of the canal(s). despite the controversies regarding its removal, the evidence-based trend has shifted towards removing and eliminating the sl. different methods have been used to remove the sl and the aim of this in vitro study was to evaluate the ability of 17% ethylenediaminetetraacetic acid (edta), 18% etid...

introduction: successful endodontic treatment depends on elimination of the microorganisms through chemomechanical debridement. the aim of this in vitro study was to evaluate the effectiveness of fragaria vesca (wild strawberry) extract (fve) on the removal of smear layer (sl). methods and materials: in this analytical-observational study, 40 extracted mandibular and maxillary human teeth were ...

introduction: this study compared the cleaning efficiency of mtwo, race and medin nickel-titanium (niti) rotary instruments. materials and methods: sixty mandibular molar mesial roots were selected with angle curvatures between 25-35 degrees and divided into three groups; each containing 20 teeth. canals were prepared with the rotary files and irrigated with 2.5% naocl solution after each instr...

introduction: effective durable adhesion between post material and dentine using resin cements is essential for longevity of restoration. the aim of this in vitro study was to compare the effect of different irrigants on smear layer removal after post space preparation. methods and materials: a total of 75 extracted anterior human teeth were selected. the canals were instrumented by rotary syst...

A fast manometric method has been designed for determining the oxygen transfer rate through cork stoppers. Thanks to this technique, it is possible measure effective diffusion coefficient of a thin wafer in few days, whereas months are required case full-length stopper. calculation also developed and validated extrapolate measured on wafers stopper, based statistical analysis experimental data ...