Search results for "hydroxide"
showing 10 items of 317 documents
Photo-induced chemiluminometric determination of Karbutilate in a continuous-flow Multicommutation assembly
2006
The present paper deals with the chemiluminescent determination of the herbicide Karbutilate on the basis of its previous photodegradation by using a low-pressure Hg lamp as UV source in a continuous-flow multicommutation assembly (a solenoid valves set). The pesticide solution was segmented by a solenoid valve and sequentially alternated with segments of the 0.001 mol l(-1) of NaOH solution, the suitable media for the formation of photo-fragments; then it passes through the photo-reactor and was lead to the flow-cell after being divided in small segments which were sequentially alternated with the oxidizing system; 2 x 10(-5) mol l(-1) of potassium permanganate in 0.2% pyrophosphoric acid.…
Domperidone plus Magnesium Hydroxide and Aluminum Hydroxide: A Valid Therapy in Children with Gastroesophageal Reflux: A Double-Blind Randomized Stud…
1994
To evaluate the efficacy of different drug combinations in treating severe gastroesophageal reflux (GER), we studied 80 children with GER. The patients were randomly divided into four groups: group A was treated with domperidone plus magnesium hydroxide and aluminum hydroxide, group B with domperidone plus alginate, group C with domperidone alone, and group D received placebo. At the time of diagnosis and 8 weeks after treatment the patients were clinically evaluated and underwent 24-h continuous esophageal pH monitoring. After treatment a complete regression of symptoms was observed in 16 of 20 patients in group A, in 8 of 20 in group B (A versus B, p < 0.018), in 9 of 20 in group C (A ver…
Thermo-oxidative stabilization of poly(lactic acid) with antioxidant intercalated layered double hydroxides
2016
Two antioxidant modified layered double hydroxides (AO-LDHs) were successfully prepared by the intercalation of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid (IrganoxCOOH) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) in the layered structure of LDH. It was found that by anchoring the phenolic moieties to the LDH layers the antioxidant power is retained in the case of Trolox, and even amplified in the case of IrganoxCOOH. A small amount of the two AO-LDHs was incorporated into poly(lactic acid), PLA, by solution mixing and melt extrusion. The thermo-oxidative stability of the composites was compared with that of the neat PLA and PLA containing free AOs. SEC analy…
Alkali activated materials using pumice from the Aeolian Islands (Sicily, Italy) and their potentiality for cultural heritage applications: Prelimina…
2020
Abstract In this paper, the potentialities of pumice-based geopolymers have been explored with the aim to evaluate their use as restoration materials. In particular, the behaviour of Aeolian pumice during alkali activation process, either alone or in binary mixtures with metakaolin, has been assessed using sodium hydroxide and sodium silicate activators. Hardened products were characterized by: X-ray diffraction; infrared spectroscopy; thermo gravimetry and electron microscopy. Furthermore, Hg-intrusion porosimetry, water absorption, compressive strength and colorimetric measurements were carried out in order to define the technical features of the produced geopolymers. The results reveal t…
Anodic alumina membranes as template for the synthesis of 1-D metal oxide and hydroxide nanostructures
2008
Anodic alumina membranes with highly ordered cylindrical pores and tuneable geometry have been prepared (pore diameters=20−200 nm; pore density 1012-1014 pores/m2; thickness: 20-100 mm) by controlling the anodizing process of aluminum in phosphoric, oxalic and sulphuric acid. The influence of different parameters (initial treatment of aluminium surface, composition of electrolyte, temperature and applied potential) on the final characteristics of the membranes have been investigated. The use anodic alumina membranes as template for the electrosynthesis of some metal hydroxides and oxides 1-D nanostructures (nanowires and nanotubes) will be also proved.
Photocurrent spectroscopy in passivity studies
2018
The aim of this article is to present photocurrent spectroscopy as useful in situ technique for the physicochemical characterization of passive films and corrosion layers. The response of (both amorphous and crystalline) semiconductor/electrolyte junction under irradiation is treated and discussed in order to get information about solid-state properties such as band gap and flat band potential. The possibility to use Photocurrent Spectroscopy (PCS), in a quantitative way, to get information on the composition of corrosion layers is discussed through a semiempirical correlation between the band gap of the oxides (or hydroxides) and the difference of electronegativity of their constituents. F…
Boosting the supercapacitive behavior of CoAl-layered double hydroxides via tuning the metal composition and interlayer space
2020
Layered double hydroxides (LDHs) are promising supercapacitor materials due to their wide chemical versatility, earth abundant metals and high specific capacitances. Many parameters influencing the supercapacitive performance have been studied such as the chemical composition, the synthetic approaches, and the interlayer anion. However, no systematic studies about the effect of the basal space have been carried out. Here, two-dimensional (2D) CoAl-LDHs were synthesized through anion exchange reactions using surfactant molecules in order to increase the interlayer space (ranging from 7.5 to 32.0 Å). These compounds exhibit similar size and dimensions but different basal space to explore excl…
Influence of calcium‐based fillers and vegetable oil on the processability and yield behavior of polyolefins
1997
The mixing of different polyolefins, several calcium-based fillers, and a type of vegetable oil was investigated. The effect of viscosity and type of polyolefin on Young's modulus, yield stress, and elongation at yield has been determined. Tensile and machine torque properties have been studied for both mixing at 180°C and at 250°C as a function of the content of several types of calcium carbonate or calcium hydroxide filler. The influence of the addition of a sunflower oil as a lubricant has also been characterized. SEM micrographs indicate some problems of the formation of agglomerates and the influence of particle size on matrix morphology and filler/matrix adhesion. Physical and chemica…
Cytotoxicity of Root Canal Filling Materials to Three Different Human Cell Lines
2001
The aim of this study was to investigate the biological compatibility of five root canal sealers (Sealapex, Endion, Super-EBA, Ketac-Endo, and AH Plus) and regular and calcium hydroxide-based gutta-percha in three different human cell lines. Cultures without root canal sealers were used as controls. Cell growth, cell morphology, cell viability, protein content of the cells, and prostaglandin E 2 (PGE 2 ) release were used as parameters to determine the cytotoxicity of the materials. The protein content of the three cell lines—nasal fibroblasts, gingival fibroblasts, and epithelial tumor cells—was significantly reduced (p ≤ 0.001) by all materials tested. Determinations of PGE 2 release show…
New insight on the lithium hydride–water vapor reaction system
2018
Abstract The reaction of lithium hydride (LiH) powder with pure water vapor (H2O and D2O) was studied by thermogravimetry and in situ infrared spectroscopy at 298 K over a large pressure range. The mean particle size of LiH is around 27 μm. At very low pressure, the hydrolysis starts with the formation of lithium oxide (Li2O). Then, both Li2O and lithium hydroxide (LiOH) are formed on increasing pressure, thus, creating a Li2O/LiOH bilayer. The reaction takes place through the consumption of LiH and the formation of Li2O at the LiH/Li2O interface and through the consumption of Li2O and the formation of LiOH at the Li2O/LiOH interface. Above 10 hPa, only the monohydrate LiOH·H2O is formed. T…