Search results for "PERFORMANCE."
showing 10 items of 4178 documents
Epoxy resins as a matrix material in advanced fiber-reinforced polymer (FRP) composites
2013
Abstract: This chapter discusses the epoxy resins which, thanks to their good and versatile properties, can be considered nowadays the most important class of thermosetting polymers. In particular the chapter first reviews both the epoxy resins commonly available on the market, including a new class of bio-derived epoxy resins, and the most-used curing agents. it then describes the principal characteristics of the epoxy resins and how it is possible to enhance them by adding several fillers to the epoxy system. Finally, the chapter analyzes the main engineering fields in which epoxy resins find application today and their possible future utilization.
Determining sulfur-containing amino acids by capillary electrophoresis: A fast novel method for total homocyst(e)ine human plasma
1999
A high-performance capillary electrophoresis (HPCE) method based on laser-induced fluorescence detection is presented here. It enables the determination of sulfur-containing amino acids within 15 min. Fluorescence of sulfur-containing amino acids in plasma is linear over a range of 50-150 micromol/L for L-methionine, 5-100 micromol/L for L-homocysteine, and 50-200 micromol/L for L-cysteine. For homocysteine, we were able to detect 1 fmol injected, equivalent to a plasma concentration of 10 nmol/L. A similar sensitivity is present for cysteine, an even lower one being found for methionine. The intra- and interassay relative standard deviations are < 1%. High-performance liquid chromatography…
Enhanced Sieving of C2‐Hydrocarbon from Methane by Fluoro‐Functionalization of In‐MOF with Robust Stability
2021
Developing efficient adsorbent materials is crucial for adsorption and separation to realize the purification of energy source and raw chemicals. Here, we report a novel and robust 3D In-based MOF built up with fluorine-functionalized ligands, QMOF-2F, with improved separation properties of C2-light hydrocarbons over methane at room temperature respect isoreticular non-fluorinated MOF. QMOF-2F shows a remarkable chemical stability in different solvents, including water, and pH (2-12). DFT calculations support the key role of fluorine-functionalization on the improved performance of QMOF-2F.
Capillary electroendoosmotic chromatography of peptides
2000
This review focuses on the current state of peptide separation by capillary electroendoosmotic chromatography (CEC). When carried out under optimised conditions, peptide separation by CEC methods represents an orthogonal and complementary technique to micro-HPLC (micro-HPLC) and high-performance capillary zone electrophoresis (HPCZE). The origin of the selectivity differences that can be achieved with these three separation techniques (CEC, micro-HPLC and HPCZE), respectively are discussed, and the current limits of performance with CEC methods documented. Peptide separations by CEC methods with n-alkyl bonded silicas or mixed-mode phases are also illustrated. The development of different v…
Super-high-speed liquid chromatography of proteins and peptides on non-porous Micra NPS-RP packings
1999
Abstract The new generation of non-porous silica RP packings commercially available from Micra Scientific was tested for separations of peptides and proteins by means of the gradient HPLC. Extremely high-speed separations were achieved using conventional chromatographic equipment: six proteins could be completely separated within six seconds. Tryptic digest peptides could be resolved in more then 40 components within 2–3 min. The effect of the experimental parameters such as temperature, flow rate etc. was investigated.
Large-area dielectric breakdown performance of polymer films
2015
In this study, large-area dielectric breakdown performances of various bi-axially oriented polypropylene (BOPP)-silica nanocomposite films are studied by utilizing the self-healing multi-breakdown method presented in the Part I of this publication. In particular, the effects of silica filler content, pre-mixing method, co-stabilizer content and film processing on the large-area breakdown performance are analyzed. Nanostructural and film cross-sectional analyses are correlated to the breakdown responses. The optimum silica filler content is found to reside at the low fill fraction level (~1 wt-%) and automatic pre-mixing of the raw materials and the optimization of the orientation temperatur…
Determination of Amino Acids by Micellar High-Performance Liquid Chromatography and Pre-column Derivatization withO-Phthalaldehyde and N-Acetyl-L-cys…
1995
Abstract Micellar liquid chromatography of proteic primary amino acids with pre-column derivatization with o-phthalaldehyde (OPA) and N-acetyl-L-cysteine was studied, using mobile phases containing a short-chain alcohol. The modification of pH gave a large variation of the retention as a result of the protonation of the carboxylate group of amino acids. Maximum resolution and adequate retentions were achieved with a 0.05 M sodium dodecyl sulphate/3% propanol mobile phase at pH 3. The reproducibility was lower than 1.0% at a 1 × 10−4 M concentration level and between 0.6 and 2.2% for 1 × 10−6 M. The determination of glycine, lysine, methionine and threonine in pharmaceutical formulations gav…
Magnesium, Oxidative Stress, and Aging Muscle
2014
Abstract Magnesium (Mg) deficiency, aside from having a negative impact on the energy production pathways required by the mitochondria to generate ATP, also reduces the threshold antioxidant capacity of the aging organism and its resistance to free-radical damage. Mg acts as an antioxidant against free radical damage of the mitochondria. Chronic Mg deficiency results in excessive production of oxygen-derived free radicals and low-grade inflammation. Chronic inflammation and oxidative stress have been identified as pathogenic factors in several age-related conditions. Aging is often associated with Mg inadequacy, muscle loss, and sarcopenia. Although the importance of magnesium as a determin…
Classification of vegetable oils according to their botanical origin using amino acid profiles established by High Performance Liquid Chromatography …
2010
Abstract A preliminary study using amino acid profiles to classify oils according to their botanical origin has been performed. Amino acid profiles were obtained from hydrolysis of proteins present in vegetable oils, and established by High Performance Liquid Chromatography (HPLC) with UV–vis detection. Proteins present in hazelnut, corn, soybean, olive, avocado, peanut and grapeseed oils were precipitated with acetone, and the residue was hydrolysed in acid medium. The amino acids obtained were derivatized with o -phthaldialdehyde and separated by HPLC. Peaks corresponding to 18 amino acids were observed using a C18 column and a gradient of acetonitrile–water in the presence of a 5 mM citr…
On the determination of underivatised fatty alcohol ethoxylates by electrospray ionisation–mass spectrometry
2006
Abstract The oligomers of fatty alcohol ethoxylates (FAEs) exhibit large sensitivity differences in mass spectrometry with electrospray ionisation (ESI–MS) and atmospheric pressure chemical ionization (APCI). Standards of the oligomers from m = 1 to 7 ethylene oxide units (EOs) and linear alkyl chains from n = 10 to 18 carbon atoms were infused to examine the relative sensitivities or response factors in several media. The response factors of the [M + H]+ and [M + Na]+ peaks in 9:1 acetonitrile/water and methanol/water media containing acid buffers increased following irregular patterns when n and m increased. In methanol/water the response factors depended on the parity of m, being larger …