Search results for "BALANCE"
showing 10 items of 1379 documents
Practical strategies for stable operation of HFF-QCM in continuous air flow
2013
Currently there are a few fields of application using quartz crystal microbalances (QCM). Because of environmental conditions and insufficient resolution of the microbalance, chemical sensing of volatile organic compounds in an open system was as yet not possible. In this study we present strategies on how to use 195 MHz fundamental quartz resonators for a mobile sensor platform to detect airborne analytes. Commonly the use of devices with a resonant frequency of about 10 MHz is standard. By increasing the frequency to 195 MHz the frequency shift increases by a factor of almost 400. Unfortunately, such kinds of quartz crystals tend to exhibit some challenges to obtain a reasonable signal-to…
On the formation of inclusion complexes at the solid/liquid interface of anchored temperature-responsive PNIPAAM diblock copolymers with γ-cyclodextr…
2017
The thermal responsive behavior of adsorbed layers of diblock copolymers of poly(N-isopropylacrylamide) (PNIPAAM) and poly((3-acrylamidopropyl)trimethylammonium chloride) (PAMPTMA(+)) with γ-cyclodextrin (γ-CD) at the solid/liquid interface has been investigated using three in situ techniques: null ellipsometry, quartz–crystal microbalance with dissipation monitoring, and neutron reflectometry. The measurements provided information about the adsorbed amounts, the layer thickness, hydration and viscoelastic properties, and the interfacial structure and composition. The copolymers adsorb to silica with the cationic PAMPTMA(+) blocks sitting as anchors in a flat conformation and the PNIPAAM ch…
Effects of power resistance training program with elastic bands on body composition, muscle strength and physical function in older women
2020
The aim of this study was to investigate the effects of a power-strength resistance program with elastic bands on body composition, physical function, and muscle strength in older women. For such purpose, a randomized controlled trial with a pre-post-intervention design was conducted. Thus, 58 healthy, physically independent, sedentary women, aged 65-85 years, were randomly allocated to the intervention (n = 28) or control group (n = 30). Measurements of body composition (total mass, total fat mass, total skeletal-muscle mass, and body fat percentage), isokinetic muscle strength of knee flexors and extensors (at 60º/second and 180º/second), and physical performance (flexibility, agility/dyn…
Zusammenfassung der Diskussion zum Thema: „Fortschritte auf dem Gebiet der parenteralen Ernährung“ und „Parenterale Ernährung unter speziellen klinis…
1977
LACKNER: DUDRICK emphasized the attempts to improve the immune competence It has been shown by Dr. CARPENTIER et al. from Belgium—(2)—that in improving the nitrogen balance he could directly increase the lymphocyte function which was measured in vitro by means of the lymphocyte transformation test.
Molecular Strategies for Targeting Antioxidants to Mitochondria: Therapeutic Implications
2015
Mitochondrial function and specifically its implication in cellular redox/oxidative balance is fundamental in controlling the life and death of cells, and has been implicated in a wide range of human pathologies. In this context, mitochondrial therapeutics, particularly those involving mitochondria-targeted antioxidants, have attracted increasing interest as potentially effective therapies for several human diseases. For the past 10 years, great progress has been made in the development and functional testing of molecules that specifically target mitochondria, and there has been special focus on compounds with antioxidant properties. In this review, we will discuss several such strategies, …
Calculation of the surface concentration of Zn(I) from the anodic voltammetric peak of zinc combined with the QCM results
2004
Deconvolution of voltammograms of anodic dissolution of zinc has proved to be possible through the electrochemical quartz crystal microbalance data and the F(dm/dQ) function. This deconvolution allows to calculate the surface concentration of Zn(I) and to obtain an estimation for the kinetic constant of the second single-electron transfer. Keywords: Zinc anodic dissolution, EQCM, Surface concentration, Deconvolution and kinetic constant
Calculation of the pH and the titratable acidity in clinically used infusion solutions.
2006
Clinically used infusion solutions are complex aqueous mixtures composed of a variety of different salts, acids, and non-electrolytes, and are characterized by composition, initial pH, and titratable acidity (TA). By rigorous treatment as a multi-composed acid-base system, pH and TA were calculated from proton dissociation equilibria, mass balance equations and electroneutrality condition. Nine were arbitrarily chosen as model solutions in which pH and TA were experimentally determined. From composition, and based on a set of apparent acidity constants (pK values) at 37 degrees C and total ionic strength 0.155 mol/l, pH was calculated by iteration. In the model solutions, measured pH was in…
Solid-State Electrochemical Method for Determining Core and Shell Size in Pd@PdO Nanoparticles
2010
Electrochemical characterization of palladium nanoparticles surrounded by a palladium oxide shell (Pd@PdO) is described from a combination of voltammetry plus electrochemical quartz crystal microbalance experiments at nanoparticle deposits on graphite electrodes in contact with aqueous H2SO4 and NaOH solutions. A method for determining the metal core size and oxide shell thickness of the Pd@PdO nanoparticles, based on a combination of conventional voltammetry of nanoparticles in DMSO solution and voltammetry of nanoparticle deposits in contact with 0.10 M aqueous NaOH solution, is described.
Study of the Chemical Conversion of Aluminum Alloys by Coupling CFDE and EQCM
2004
The ability of the channel flow double electrode (CFDE) technique and electrochemical quartz crystal microbalance (EQCM) for studying in situ chromate phosphate conversion coating on 5182 aluminum alloys was explored. It was first demonstrated that aqueous Cr(VI) can be analyzed quantitatively with the CFDE technique by reduction into Cr(III) on a graphite electrode. Samples used for EQCM were quartz plated by physical vapor deposition using a 5182 alloy target, allowing thin layers of aluminum alloys with a similar chemical composition to be obtained. EQCM was adapted in order to account for the hydrodynamic conditions in an industrial process, by placing the quartz in a flow cell. In orde…
In-situ characterisation of organosilane films formation on aluminium alloys by electrochemical quartz crystal microbalance and in-situ ellipsometry
2005
Abstract Organosilane pre-treatments have been studied intensively during the last years in order to replace hexavalent chromium conversion treatments. The aim of this study is to follow in-situ the formation of this organosilane layer in solution. Two in-situ techniques, spectroscopic ellipsometry and electrochemical quartz crystal microbalance, were used to investigate the mechanism and the kinetics of this protective film formation. In-situ measurements highlight that the organosilane film observed after the drying process is not formed into the solution, but during the emersion and drying step. Hence, it has been possible to characterise the presence of a very thin organosilane layer in…