Search results for "Gel"
showing 10 items of 3561 documents
Effect of the Al/Si atomic ratio on surface and structural properties of sol-gel prepared aluminosilicates
2003
Abstract A series of aluminosilicates with an Al/Si ratio ranging from 0 to ∞ (0 for pure silica and ∞ for pure alumina) was prepared by sol–gel process and characterized by surface and structure techniques. Aluminum tri sec butoxide and tetramethylorthosilicate were used as precursors for the sol–gel synthesis. The acidic properties of the oxides were studied by determination of the zero point charges, through mass titration method, and, for selected samples, by FT-IR spectroscopy of adsorbed pyridine used as a probe for both Bronsted and Lewis acidity. A dependence of the acidity on the Al/Si atomic ratio was found. According to the X-ray diffraction patterns, all the oxides have an amorp…
Quantitative determination of surface area of silica gel particles by near infrared spectroscopy and chemometrics
2008
Abstract Surface areas of silica gel particles have been quantitatively determined by using near infrared spectrometry and chemometrics. Surface areas of six silica gel samples with varying surface area (300–750 m2/g) have been determined by the common Brunauer–Emmett–Teller (BET) method and used in preparing mixtures of silica gel samples with varying surface area in the ranges 300–474 and 500–750 m2/g. The near infrared spectra of the mixtures were measured and the spectral profiles calibrated against the calculated surface area of the mixtures as dependent variable using partial least squares (PLS) technique. The models obtained from the calibrations were then used in predicting the surf…
Comparative analysis of short tandem repeats and single nucleotide polymorphisms on the Y-chromosome in Germans, Chinese and Thais.
2003
We have typed genomic DNA samples from 95 individuals from Western Germany, 78 individuals from Bangkok/Thailand and 56 individuals from Chengdu/China for 11 Y-chromosomal diallelic polymorphisms and eight short tandem repeat (STR) systems. For single nucleotide polymorphism (SNP) analysis, a rapid method was applied using the single base extension technology (minisequencing) in combination with capillary electrophoresis. PCR products for SRY-8299, Tat, SRY2627, 92R7, SRY1532, M9, M13, M17/M19 and M20 were pooled and used as templates for the commercially available SNaPshot kit. In addition to these ten SNPs we also tested the Y-chromosomal diallelic Alu repeat insertion DYS287 (YAP) by aga…
Core/Shell Gel Beads with Embedded Halloysite Nanotubes for Controlled Drug Release
2019
The use of nanocomposites based on biopolymers and nanoparticles for controlled drug release is an attractive notion. We used halloysite nanotubes that were promising candidates for the loading and release of active molecules due to their hollow cavity. Gel beads based on chitosan with uniformly dispersed halloysite nanotubes were obtained by a dropping method. Alginate was used to generate a coating layer over the hybrid gel beads. This proposed procedure succeeded in controlling the morphology at the mesoscale and it had a relevant effect on the release profile of the model drug from the nanotube cavity.
Effects of different intra canal medicaments on the push out bond strength of endodontic sealers
2016
BACKGROUND One of the essential properties of the root canal sealers is the adhesion to root canal dentin and their higher bond strength decreases the microleakage. The aim of the present study was to compare the effect of Different Intracanal medicaments on the push out bond strength of AH26 and MTA Fillapex sealers. MATERIAL AND METHODS A total of 104 one-rooted extracted human teeth were divided into 4 (n=26) experimental groups. After the cleaning and shaping, the root canals were filled with Ca(OH)2, triantibiotic paste (TAP), Metapex or 2% chlorhexidine gel for two weeks. Then, intracanal medicaments were rinsed away and the samples in the sub-groups were obturated with gutta-percha a…
Short-Term Results in Evaluating a Gingiva-Adhesive Hydrophobic-Chlorhexidine-Gel for Chronic Periodontitis
2014
Background and Aims: Oral mucosa and interproximal spaces of the teeth could favor the colonization of periodontopathogenic bacteria, which could be targeted by chemical antiplaque agents such as chlorhexidine, present in different oral hygiene products, thus improving the control of biofilm growth and delaying microbial accumulation. The study aimed to evaluate whether the use of a hydrophobic gel with good gingival adhesion for 14 days after the scaling and root planing of patients with chronic periodontitis would improve the treatment outcome, when compared with the use of a regular hydrophyllic gel.Material and Methods: Patients with moderate disease were included in two study groups. A…
Application of TLC and GC-MS to the detection of capsaicin from hot peppers(Capsicum annuum)
2004
Capsaicin was extracted from red hot pepper (Capsicum annuum) fruits and from commercial red hot pepper powder and separated on silica gel 60 plates with concentration zone (Merck); toluene-acetone-chloroform, 45 + 30 + 25 ( v/v ), was used as mobile phase. Detection was performed by exposure to iodine vapor. The spots assumed to arise from capsaicin were removed from the plate and the components were extracted with chloroform. The extracts were analyzed by gas chromatography combined with mass spectrometry.
Supramolecular PEG-co-oligo(p-benzamide)s prepared on a peptide synthesizer.
2007
An automated synthesis protocol has been developed for the preparation of oligo(p-benzamide)s on solid support using a commercial peptide synthesizer employing a variation of standard Fmoc chemistry. Bis(trichloromethyl carbonate) in NMP was used to activate the aromatic carboxylic acids for acylation of secondary aromatic amines on solid support. N-Protected hepta(p-benzamide) was automatically prepared on solid support and manually converted to a solid supported block co-oligomer by attaching a poly(ethylene glycol) chain. Cleavage from the support could be achieved with minimal loss of the p-methoxybenzyl N-protective group. While the N-protected block co-oligomer was molecularly dissolv…
Methodical Studies in the Separation of Chlorophyll-Protein Complexes by Polyacrylamide Gel Electrophoresis
1980
Summary Chlorophyll-protein complexes from thylakoids of Sinapis alba plants were separated, using Tris-HCl and Tris-borate buffer in the sodium dodecyl sulphate acrylamide gel electrophoresis. In the electrophoretogram with Tris-borate buffer, 6 bands could be characterized in the gel pattern. In addition to the three major green zones (P-700-chlorophyll a-protein, light-harvesting chlorophyll a/b-protein, free pigment zone), which were also observed in experiments with the Tris-HC1 buffer, three further bands (LHCP 1 , LHCP 2 , CPa) were electrophoretically separated. An elongation of the electrophoretical period resulted especially in a decrease of the proportion of the light-harvesting …
Chlorophyll-Protein Complexes of Chlorella fusca
1980
Chlorophyll-protein complexes from thylakoids of the normal type and two mutants of Chlorella fusca were separated using sodium dodecyl sulfate acrylamide gel electrophoresis (PAGE). The properties of the chlorophyll-protein complexes of the three strains of Chlorella were compared. Standard curves were set up for the characterization of the chlorophyll-proteins. In every electrophoretic separation of chlorophyll-protein complexes, a certain amount of pigment is separated from the protein. We tried to keep that amount as low as possible by mild solubilization and by working in low temperature. Under these conditions, we obtained several new chlorophyll-proteins in addition to the P-700-chl…