This study aimed at testing how active and inactive enamel caries lesions differ by their degree of resin infiltration, and whether the choice of acid pretreatment plays a crucial role. Four examiners assessed 104 human molars and premolars with noncavitated enamel lesions and classified them as 'active' or 'inactive' using the Nyvad criteria. Forty-five teeth were included in this study after ...

G . H evesy has written that [6] 1 " In view of the I.great similarity b etween hafnium and zirconium, i t ris hardly possible to separate these two elements in a lsingle operation ." A simple one-step separation c adequ a te for analytical work has still to be developed for hafnium-ziTconium mixtures, although recent work employing ion exchange has developed suitable methods for the separation...

Chemical recycling of Polyethylene terephthalate, PET, wastage has been investigated in this study. The aim of this work is recovery of terephthalic acid and ethylene glycols from PET waste. This process has been done in two stages. At the first stage, reaction between PET waste and sodium hydroxide for production of ethylene glycol and sodium terephthalate solution carried out in a stainless s...

The chemical potentials of each solute in an aqueous mixture of two electrolytes have been determined for many systems. For example, the activity coefficients of both hydrochloric acid and sodium chloride in mixed aqueous solution have been derived from emf measurements [I]. The isopiestic vapor pressure method has been used [2] to determine the activity coefficients of each solute in aqueous m...

The chromophore of C-phycocyanin, phycocyanobilin, was cleaved from the protein with methanol, concentrated hydrochloric acid, or subtilisin BPN’. The pigments obtained were converted to their dimethyl esters and purified by preparative high pressure liquid chromatography and examined for purity by analytical high pressure liquid chromatography on silica gel. They were characterized by proton t...

Health effects of acute exposure • The main routes of exposure to hydrogen chloride are via inhalation, or skin or eye contact and exposure to hydrochloric acid is predominantly by ingestion, or skin or eye contact • Inhalation may cause irritation to nose and upper respiratory tract, ulceration, coughing, chest tightness and shortness of breath. Higher concentrations cause tachypnoea, pulmonar...

We describe a procedure for the determination of hydrochloric acid concentration in gastric juice by means of a conductometric titration of the 50-fold diluted sample with an aqueous ammonia solution. The conductometric method of endpoint indication leads to a definite location of the equivalence point in the titration of hydrochloric acid. The proposed method is simple and accurate and shows a...

Ultrasound assisted extraction (UAE), purification, characterization and antioxidant activity of laminarin from Irish brown seaweeds Ascophyllum nodosum and Laminarina hyperborea were investigated. UAE was carried out using 60% ultrasonic power amplitude and 0.1 M hydrochloric acid for 15 min. Separately, solid-liquid extraction was carried in an orbital shaker using 0.1 M hydrochloric acid at ...