Search results for "Preparation method"
showing 10 items of 31 documents
ChemInform Abstract: Monolayers and Langmuir-Blodgett Multilayers of Discotic Liquid Crystals?
1990
The field of monolayer and multilayer films of discotic LCs is at its very beginning. The scope and limitations of this preparation method have not yet been explored, and little is known about the structures obtainable. However, the potential access to extraordinary, ordered thin films is fascinating, and will stimulate research in the future.
Experimental taphonomy in museums: Preparation protocols for skeletons and fossil vertebrates under the scanning electron microscopy
2008
Natural history institutions use different standards and methods to prepare and preserve skeletons of both modern and fossil vertebrates. These standards and treatments may be considered as taphonomic agents of museum collections. Modifications may occur during preparation, affecting the integrity of bone tissues and skeletons or their molecular and geochemical composition. The present evaluation uses a Scanning Electron Microscope (SEM) to analyze the most common preparation methods and standards. The aim of this paper is to evaluate preparation methods to determine those that provide the best SEM observations and those that best preserve osseous tissues and least damage fossil surfaces. I…
Synthesis and characterization of titanium dioxide and titanium dioxide–based materials
2021
Abstract The aim of the chapter is to describe some different preparation methods and characterization techniques for bare, supported, and coupled TiO2 samples used in different fields. Particular attention has been paid both to the fundamental aspects of the different TiO2 preparation and characterization methods and the practical applications that the results obtained can have. Various examples have been reported from the literature to demonstrate the usefulness that students and scientists working with TiO2-based materials in different research areas can derive from various characterizations.
Sample Preparation for Mass-spectrometry-based Proteomics Analysis of Ocular Microvessels
2019
The use of isolated ocular blood vessels in vitro to decipher the pathophysiological state of the eye using advanced technological approaches has greatly expanded our understanding of certain diseases. Mass spectrometry (MS)-based proteomics has emerged as a powerful tool to unravel alterations in the molecular mechanisms and protein signaling pathways in the vascular beds in health and disease. However, sample preparation steps prior to MS analyses are crucial to obtain reproducible results and in-depth elucidation of the complex proteome. This is particularly important for preparation of ocular microvessels, where the amount of sample available for analyses is often limited and thus, pose…
Quantitative and qualitative control of antineoplastic preparations: Gravimetry versus HPLC.
2019
This article compares gravimetry vs. high-performance liquid chromatography (HPLC) as quality control (QC) methods for paclitaxel, docetaxel and oxaliplatin preparations. We aimed at assessing the preparation method reliability in our hospital, evaluating compounding accuracy and estimating the influence of personnel training and standardized homogenization on compounding accuracy. Agreement, correlation, concordance, accuracy and precision between methods were evaluated for each drug. Conforming preparation percentages (CPs) at different tolerance limits (TLs) and compounding accuracy were calculated for each method and drug. Compounding accuracy was compared before and after personnel tra…
Trace analysis by ion mobility spectrometry: From conventional to smart sample preconcentration methods. A review.
2018
Ion mobility spectrometry (IMS) is a rapid and high sensitive technique widely used in security and forensic areas. However, a lack of selectivity is usually observed in the analysis of complex samples due to the scarce resolution of the technique. The literature concerning the use of conventional and novel smart materials in the pretreatment and preconcentration of samples previous to IMS determinations has been critically reviewed. The most relevant strategies to enhance selectivity and sensitivity of IMS determinations have been widely discussed, based in the use of smart materials, as immunosorbents, aptamers, molecularly imprinted polymers (MIPs), ionic liquids (ILs) and nanomaterial. …
Different preparation methods of bare and doped carbon nitride (C3N4) employed for selective photocatalytic oxidations
2018
Different preparation methods of bare and doped carbon nitride (C3N4) employed for selective photocatalytic oxidations
Determination of macrolide antibiotics in meat and fish using pressurized liquid extraction and liquid chromatography–mass spectrometry
2008
We developed a method for determining the quantities of seven macrolide antibiotics in meat and fish by using pressurized liquid extraction (PLE) and liquid chromatography-mass spectrometry with electrospray ionization (LC-(ESI)MS). The PLE was optimized with regard to solvents, temperature, pressure, extraction time and number of cycles. The optimum conditions were: methanol as the extraction solvent; a temperature of 80 degrees C; a pressure of 1500psi; an extraction time of 15min; 2 cycles; a flush volume of 150% and a purge time of 300s. All recoveries for macrolide antibiotics were over 77% at 200mug/kg, except for erythromycin, which was 58%. The repeatability and reproducibility on d…
Die bestimmung der molekulargewichtsverteilung von nichtkristallisierenden polymeren mit dem elektronenmikroskop, 7. Präparation durch verdampfung de…
1977
A preparation method is described by means of which it is possible to transfer individual molecules of a high molecular weight polymer on a support, in order to determine their mass and therefrom their molecular weight distribution, using our previously published electron microscopic method. The advantages of the new procedure as compared to the previously described freeze-drying are 1 that the range of solvents, which can be used is much larger, and 2 that the preparation is performed by evaporation from a dilute solution, which means that the molecules are distributed statistically on the support. The risk of formation of associates is avoided by keeping the polymer concentration correspo…
Influence of Acidic Support in Metallocene Catalysts for Ethylene Polymerization
2001
Abstract We studied a ZSM-5 zeolite as metallocene support for ethylene polymerization. We transformed the Na-ZSM-5 into H-ZSM-5. After the cation exchange, the zeolite was calcined at three different temperatures. Characterization of the material indicated that by means of the calcination procedure it is possible to produce dealuminization with an increase in extraframework aluminum (EFAL). We prepared zirconocene-supported catalysts on zeolitic supports using two preparation methods. The higher activity was observed with the zirconocene supported on ZSM-5 pretreated at 900°C. We think that the dealuminization process generates an increase in EFAL. This EFAL is responsible for the higher a…