We present the hysteresis of the response of the poly(N-isopropylacrylamide)-co-acrylic acid microgel-based etalons to solution temperature and pH changes. We find that the optical hysteresis of the etalon can be controlled using various solution ionic strengths and/or counterions, as well as by varying the microgel's acrylic acid concentration.

Six dissociable groups exist in tetrahydrofolic acid in the range Ho -3.0 to pH 14. The assignments in tetrahydrofolic acid by titrimetric and spectrophotometric comparisons with model compounds, +uninobenzoylglutamic acid and 2-amino-6,7-dimethyl-5,6,7,8-tetrahydro-4-pteridinone, are as follows: acidic ionization of amide, pK’ 10.5; Ns, pK’ 4.82; y-carboxyl, pK’ 4.8; cr-carboxyl, pK’ 3.5; N1, ...

background: bonding of molar tubes is becoming more popular in orthodontics. occasionally, these bonding are done on posterior porcelain crowns or bridges. the purpose of this study was to evaluate the shear bond strength of buccal tubes on feldspathic porcelain crowns with two different methods. materials and methods: forty porcelain right molar crowns were fabricated for this study. the crown...

effects of water on the catalytic performances of movtenbo catalyst in the oxidation of propane to acrylic acid have been investigated at different reaction temperatures and different steam contents. obtained results show that both catalytic performances and catalyst structure are very sensitive to the presence of water vapor in the reaction feed. presence of water induces some structural modif...

the potential use of nano technology for improving of withdrawal resistance of nail and screw in wood was evaluated. for this, the maintenance strength of nail and screw was measured under dry and wet conditions for poplar wood (populus nigra) coated with common paints in furniture industry and nano-particles. specimens with dimensions of 15×5×5 cm3 (l×r×t) were cut from poplar wood (populus ni...

background and aims. bleaching can considerably reduce shear bond strength (sbs) of orthodontic brackets bonded with composite adhesives. application of antioxidants is a method to reverse the negative effect of bleaching on composite-to-enamel bond. however, the efficacy of antioxidants in increasing the sbs of brackets bonded using resin-modified glass-ionomer cement (rmgic) has not been stud...

Objective. To determine the effect of lactic acid at various concentrations on the shear bond strength of orthodontic brackets bonded with the resin adhesive system before and after water storage. Materials and Methods. Hundred extracted human premolars were divided into 5 treatment groups and etched for 30 seconds with one of the following agents: lactic acid solution with (A) 10%, (B) 20%, (C...

background. repairing aged composite resin is a challenging process. many surface treatment options have been proposed to this end. this study evaluated the effect of different surface treatments on the shear bond strength (sbs) of nanofilled composite resin repairs. methods. seventy-five cylindrical specimens of a filtek z350xt composite resin were fabricated and stored in 37°c distilled water...