17,046 research outputs found
Design of pH sensor for liquid cell Transmission electron microscopy
No full textElectron microscopy has enabled us to visualize objects that are not observable with a light microscope. With Transmission electron microscope observation up to subatomic level is possible. Generally, the sample is under vacuum in an electron microscope. But in real life sample is under influence of environmental conditions like liquid, gas, temperature. Development in Microelectromechanical systems has made it possible to make nanocell, which encloses sample and provide different stimuli like gas, liquid, voltage, temperature.Imaging in liquid environment contains encapsulated liquid, which allows high energy electron beam passes through thin windows. While the electron beam passing through the liquid, the interaction of both splits water and generates radiolysis products. These radiolysis products contain gases, ions, radicals, and other chemical compositions. These products affect the chemistry in liquid and therefore the observations in the experiment. So it is important to quantify these generated species. One of the species that is generated due to radiolysis is Hydrogen ion. Because of this, the pH of the liquid changes. Numerical studies are available to quantify this pH change but species generation data is interpolated to several orders of magnitude and very limited experimental work is available.The goal of this thesis was to measure pH change due to radiolysis. For this, two problems need to tackle simultaneously, making micro size pH sensor on-chip and trying to find out what species due to radiolysis has the potential to affect pH measurements. Radiolysis generates 15 species for pure water and characterizing all of them is difficult. So here approach is taken to measure species effect just outside the electron beam area, which reduces to only 5 species to consider. Species generation and its effect on the platinum electrode are analyzed. For Ultrapure water, the measured voltage shift was negative and for acidic solutions, it was positive with an increase in dose rate. The reason for this could be the generation of excess Hydrogen peroxide for acidic solutions and generation of excess Superoxide for neutral pH solutions. So it is important to shield the effect of these two species for successful pH measurement just outside the beam region. The optimization code is written to decide the place and thickness of two pH measuring electrodes. From literature, it is found that Iridium oxide has a selectivity of 0.0001 for Hydrogen peroxide. Results from the optimization code conclude that the sensing layer should have minimum selectivity for Superoxide of 0.1, to measure any meaningful pH change outside the beam area.pH sensing characteristics of the Iridium oxide layer reveals maximum error is 0.4 pH. However, according to simulations outside the beam area, the maximum pH change is 1.34 pH. From the optimization code dimensions of two pH sensing electrodes are decided. Considering maximum error from pH measurement experiments and error from species interference from simulations, an electrode configuration has been designed. The design allows pH measurement for the dose rate 50000000 Gy/s and above for initial pH of solution ranging from 6 to 8.Mechanical Engineering | Micro and Nano Engineerin
Isolation of anaerobic, extremely thermophilic, sulphur metabolising archaebacteria from New Zealand hot springs
No full textEnrichments of New Zealand geo-thermal samples, initiated in anaerobic sulphur-containing media and incubated at temperatures above 85°C, yielded rod and coccal shaped organisms which possessed archaebacterial characteristics. Pure cultures were isolated and characterised. Five of the seven isolates, which were rod-shaped organisms and did not have an obligate requirement for sulphur respiration, were similar to Ther-moproteus sp. but had more neutral pH optima for growth. Three of these five Thermoproteus sp. were obligate heterotrophs, which has not previously been reported. The two coccal isolates had an obligate requirement for sulphur as an electron acceptor and were similar to Desulfurococcus sp. but again with more neutral pH optima for growth
An intracellular pH gradient in the anammox bacterium Kuenenia stuttgartiensis as evaluated by (31)P NMR
No full textThe cytoplasm of anaerobic ammonium oxidizing (anammox) bacteria consists of three compartments separated by membranes. It has been suggested that a proton motive force may be generated over the membrane of the innermost compartment, the “anammoxosome”. 31P nuclear magnetic resonance (NMR) spectroscopy was employed to investigate intracellular pH differences in the anammox bacterium Kuenenia stuttgartiensis. With in vivo NMR, spectra were recorded of active, highly concentrated suspensions of K. stuttgartiensis in a wide-bore NMR tube. At different external pH values, two stable and distinct phosphate peaks were apparent in the recorded spectra. These peaks were equivalent with pH values of 7.3 and 6.3 and suggested the presence of a proton motive force over an intracytoplasmic membrane in K.stuttgartiensis. This study provides for the second time—after discovery of acidocalcisome-like compartments in Agrobacterium tumefaciens—evidence for an intracytoplasmic pH gradient in a chemotrophic prokaryotic cell.BiotechnologyApplied Science
α—Oximinoacetoacetarylamide Benzoyl Hydrazones as Gravimetric Reagents for Palladium(II)
No full textDepartment of Chemistry, Sardar Patel University, Vallabh Vidyanagar-388 120
Manuscript received 5 June 1974; accepted 22 January 1976
The chelating property of benzoylhydrazones of α-oximinoacetoacetanilide and o-toluidide with various metallic ions has been studied. Palladium(II) can be estimated by these reagents over a wide range of pH from 0.7-1.0; in presence of cations such as copper (II) and nickel (II), estimation is possible in acidic media (from pH 0.5-0.9)
Release Kinetics of Potassium, Calcium, and Iron Cations from Carboxymethyl Cellulose Hydrogels at Different pH Values
No full textQu Y, Haverkamp R, Jin Z, Jakobs-Schönwandt D, Patel A, Hellweg T. Release Kinetics of Potassium, Calcium, and Iron Cations from Carboxymethyl Cellulose Hydrogels at Different pH Values. ChemPlusChem. 2023;88(12): e202300368.In an in-depth study of the mechanism of cation release from carboxymethyl cellulose hydrogels synthesized through Schiff base reaction, we analyze the differences in the release kinetics of potassium, calcium, and iron cations with Peleg model at pH values of pH 3.5 and pH 8.5 using ICP-OES (inductively coupled plasma optical emission spectroscopy) technique. It is confirmed that the higher valence and alkaline condition favors slow cation release compared to acidic condition. Regardless of the pH value, the correlation length of the hydrogel determined by SAXS method (small-angle X-ray scattering) has a decisive influence on the cation release rates, which becomes larger as the correlation length increases. © 2023 Wiley-VCH GmbH
Concept and development of an autonomous wearable micro-fluidic platform for real time pH sweat analysis
No full textIn this work the development of an autonomous, robust and wearable micro-fluidic platform capable of performing on-line analysis of pH in sweat is discussed. Through the means of an optical detection system based on a surface mount light emitting diode (SMD LED) and a light photo sensor as a detector, a wearable system was achieved in which real-time monitoring of sweat pH was performed during 55 minutes of cycling activity. We have shown how through systems engineering, integrating miniaturised electrical components, and by improving the micro-fluidic chip characteristics, the wearability, reliability and performance of the micro-fluidic platform was significantly improved
Mycobacterium tuberculosis Responds to Chloride and pH as Synergistic Cues to the Immune Status of its Host Cell
No full textPubMed ID: 23592993This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Ion-Exchange Properties of Poly-(5-Acetyl-4-Hydroxy-1, 3-Phenylene)-1,2-Ethanediyl with Bivalent Ions
No full textDepartment of Chemistry, Sardar Patel University, Vallabh Vidyanagar-388 120 (Gujrat)
Manuscript received 27 June 1980, revised 1 November 1980, accepted 10 March 1981
The polymer prepared from o-hydroxyacetophenone and 1,2-dichloroethane by Friedel-Craft's condensation showed to be a selective chelating ion-exchange resin for copper, cobalt, manganese, zinc and iron ions. A batch equilibration method was employed in the study of the selectivity of metal ion uptake over a wide pH range and in media of various ionic strengths
Exploring the effect of the pH on the corrosion of multilayer nickel-chromium coatings
No full textThe impact of the pH on the corrosion of microporous nickel-chromium coatings has been explored at localised scale by Scanning Electrochemical Microscopy and validated by potentiodynamic polarisation measurements. Results not only reveal the correlation between both techniques but also enables to identify the different corrosion rate after increasing the electrolyte aggressiveness varying the pH. However, independently of the pH, a similar corrosion mechanism was determined: the cross-section micrographs (by Field Emission-Scanning Electron Microscope) have revealed an isotropic growth of the actives sites at early-stage corrosion as well as the attack of different nickel layers during the corrosion propagation.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Yaiza Gonzalez Garci
Il dibattito italiano su principi e clausole generale e l'ideale della certezza del diritto
No full textThis essay provides a critical assessment of the current Italian debate on general clauses and principles as set forth in a recent book edited by Giovanni D’Amico. The Author focuses on the role that legal certainty has played so far in this discussion and suggests that its impact on real life decisions and the functioning of the legal system has been greatly undervalued. The essay’s central argument attempts to demonstrate that, in the interpretation of general clauses and their translation into specific rules, the objective of legal certainty should be pursued and can ultimately be achieved
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