Search results for "Plate"
showing 10 items of 1689 documents
From ceria nanotubes to nanowires through electrogeneration of base
2009
The preparation of Ce(OH)3/CeO2 nanostructures (NSs) through electrogeneration of base into anodic alumina membranes was studied. The effects of solvent (alcohol and/or water), Ce3? partner anion nature (chloride or nitrate) and concentration, applied potential or current density in driving the morphology toward nanowires (NWs) and/or nanotubes (NTs) was described. The structural analysis performed by X-Ray Diffraction and Raman Spectroscopy allowed to evidence that the presence of Ce(IV) into the nanostructures strongly depends on the oxygen content in the growing environment.
Imprinted chiral stationary phases in high-performance liquid chromatography
2001
Polymers imprinted with chiral templates offer a new generation of tailor-made chiral stationary phases (CSPs) with predictable selectivities. This review summarizes the present state of the art of molecular imprinting to generate tailor-made CSPs and provides an overview of the main factors involved in the manufacturing process that are crucial to the chromatographic performance of the phases.
Development of a semiautomated procedure for the synthesis and evaluation of molecularly imprinted polymers applied to the search for functional mono…
2001
Abstract A previously described scaled-down version of the established monolith procedure, where molecularly imprinted polymers (MIPs) are prepared on the bottom surface of chromatographic vials [Anal. Chem. 71 (1999) 2092] has been here further optimised with respect to its full automation. The protocol results in savings of time and reagents compared to the monolith procedure, allowing ca. 60 polymers (∼50 mg each) to be synthesised in parallel. Both blank and imprinted polymers are then evaluated in situ by equilibrium batch rebinding tests. Each step in the synthesis and evaluation was considered with the aim of achieving an automated method with wide applicability with regards to templ…
Theory-based improvements of continuous polymer fractionation demonstrated for poly(carbonate)
1992
For the first time, a quantitative theoretical analysis (liquid/liquid phase equilibria treated by means of the continuous thermodynamics) of the operating characteristics of continuous polymer fractionation (CPF) was performed. The results of these calculations were compared with data published for CPF of polyethylene. It turned out that the efficiency of the conventional CPF corresponds to approximately two theoretical plates only. For this reason, several improvements, suggested by theoretical considerations, were realized experimentally, for which purpose the system dichloromethane/diethylene glycol/bisphenol-A polycarbonate was chosen. The pulsating sieve-bottom column was replaced by …
Preparative separation of proteins and enzymes in the mean molecular-weight range of 10,000–100,000 LiChrosorb diol® packing by high-performance size…
1979
Abstract LiChrossorb Diol® packing has been to be well-suited for the separation of proteins and enzymes according to a size-exclusion mechanism in a mean molecular-weight (MW) range between 10,000 and 100,000. Loadability of a small bore column of 6 mm I.D. (A) and a large-bore column of 23.5 mm I.D. (B), both of 250 mm in length, were examined. Defining a 20% decrease of the number of theoretical plates as loadability limit the volume load at constant mass of chymotrypsinogen as representative test solute was ≈ 100 μl for column (A) and 1500 μl for column B at 0.78 · 10-5 g/g of packing for column A and 0.78 · 10-6 g/g of packing for column B, respectively. Mass load to constant injection…
Synthesis of cyclic dipeptide templates, their incorporation into peptides and studies on their conformational and biological properties.
2009
This study investigated the diastereoselective synthesis of three dipeptide templates 1, 2 and 3, which may be regarded as conformationally restricted analogs of H-Gly-Xaa-OH, in which Xaa constitutes an aromatic amino acid. Bond formation between α-C of Gly and the aromatic moiety was achieved by proton-catalyzed intramolecular electrophilic aromatic substitution. The absolute configuration of the dipeptide templates was determined by single-crystal X-ray crystallography or by nuclear Overhauser enhancement measurements. A protective group strategy was elaborated to allow their incorporation into peptide sequences by liquid phase as well as by solid-phase peptide synthesis. The templates w…
Non-steroidal anti-inflammatory agents. Part 23. Synthesis and Pharmacological Activity of Enaminones which inhibit both bovine cyclooxygenase and 5-…
1998
The synthesis and stereochemical characteristics of pyrrolidino-, isoquinolino- and indolo-enaminones 2–11 are reported. The inhibition of cyclooxygenase was determined in a bovine thrombocyte intact cell assay and that of 5-lipoxygenase using intact bovine polymorphonuclear leucocytes. Except compound 2c′ which is a well-balanced dual inhibitor of both enzymes, all other enaminone derivatives are weak inhibitors of both cyclooxygenase and 5-lipoxygenase. Structure-activity relationships of the enaminones in relation to known anti-inflammatory drugs are discussed.
Hierarchical Imprinting Using Crude Solid Phase Peptide Synthesis Products as Templates
2003
The crude products resulting from solid-phase peptide synthesis can be used as epitope templates to generate surface-confined sites for the template and larger peptides containing the template motif. This offers a facile route to robust affinity stationary phases for the chromatographic separation of peptides.
Synthesis of high-surface area CeO2 through silica xerogel template: influence of cerium salt precursor”;
2010
Abstract Ceria nanosized oxides with high surface area were synthesized by means of a templating approach, using a porous silica xerogel with surface area as high as 718 m2/g. After impregnation of the silica template with the cerium salt solution and further calcination at 600 °C, the final ceria oxide was recovered by dissolving the silica framework in NaOH solution. The effect of cerium counteranion, nitrate or chloride, on the textural and reduction properties of the ceria oxide was examined. Characterizations by BET and pore size distribution, XRD, TPR and SEM/EDX techniques were performed. The silica xerogel templated approach resulted in the preparation of ceria with surface area of …
Application of Nanoemulsions in the Synthesis of Nanoparticles
2018
Abstract Nanodroplets of a liquid in another immiscible liquid provide confined spaces in which chemical reactions can take place. If these reactions lead to the formation of nanoparticles, as it is the case for polymerization or precipitation reactions, nanodroplets can be used as templates for particle synthesis. The most common example of application of nanoemulsions for particle synthesis is the preparation of polymer nanoparticles by miniemulsion polymerization, but also inorganic materials can be produced in this way. Nanoemulsions are as well an excellent platform for preparing polymer/inorganic hybrid nanoparticles, either by using directly the templating effect of droplets during t…