Influence of Hydrochloric Acid Concentrations on the Formation of AgCl-Doped Iron Oxide-Silica Coreshell Structures

2012 ◽  
Vol 77 ◽  
pp. 184-189 ◽  
Author(s):  
Norsuria Mahmed ◽  
Oleg Heczko ◽  
Simo Pekka Hannula
Keyword(s):  
Iron Oxide ◽  
Hydrochloric Acid ◽  
Room Temperature ◽  
Silver Chloride ◽  
Ambient Atmosphere ◽  
High Concentration ◽  
Wet Chemistry ◽  
Hcl Concentration ◽  
Average Size ◽  
Very High

Silver chloride (AgCl) nanoparticles with the average size of about 45 nm have successfully been doped onto the iron oxide-silica coreshell surfaces by a simple room temperature wet chemistry method under ambient atmosphere. The Stöber process has been used to make the coreshell structure, followed by adsorption of Ag+ species on silica surface prior to the addition of hydrochloric acid (HCl) and polyvinylpyrrolidone (PVP). The concentration of HCl acid that was used to induce the growth of AgCl particles was varied from 0.12 mM to 12x103 mM of concentrations. Results showed that at a very high concentration of HCl (12x103 mM), large AgCl agglomerates (0.3-0.6 microns) with irregular cubic-like morphology were obtained while at a very low, 12 mM HCl concentration, 30-50nm AgCl particles having a uniform cubic morphology were observed. Concentrations below 12 mM result in irregular and nearly spherical morphology of AgCl particles with a smaller size (28-60 nm). UV-Vis absorption of the composite materials showed absorption in the visible wavelength indicating that Ag nanoclusters might coexist together with AgCl particles.

FeII oxidation by molecular O2 during HCl extraction

2011 ◽  
Vol 8 (2) ◽  
pp. 190 ◽  
Author(s):  
Katharina Porsch ◽  
Andreas Kappler
Keyword(s):  
Hydrochloric Acid ◽  
Room Temperature ◽  
Low Ph ◽  
Geochemical Modelling ◽  
Acid Extraction ◽  
Biogeochemical Processes ◽  
Temperature Oxidation ◽  
Anoxic Conditions ◽  
Hcl Concentration ◽  
Formation Of Complexes

Environmental contextIn the environment, iron exists mainly as FeII and FeIII and plays an important role in biogeochemical processes. The FeII and FeIII content is often quantified by hydrochloric acid extraction and the acid is thought to prevent FeII oxidation by oxygen. However, we found that with increasing HCl concentration and temperature, oxidation of FeII by oxygen is accelerated. Therefore, in order to obtain reliable results extractions should be performed with dilute HCl or in the absence of oxygen. AbstractHCl is commonly used to stabilise FeII under oxic conditions and is often included in Fe extractions. Although FeII oxidation by molecular O2 in HCl is described in the field of hydrometallurgy, this phenomenon has not been systematically studied in environmentally relevant systems. The extent of FeII oxidation by O2 during extraction of soils and magnetite by HCl and in HCl/FeCl2 solutions was therefore quantified. FeII was stable in 1 M HCl at room temperature for several days, whereas in 6 M HCl at 70°C, 90% of the FeII was oxidised within 24 h. In the absence of O2, no FeII oxidation occurred. Experiments at low pH with increasing H+ or Cl– concentration alone and geochemical modelling suggested that the formation of complexes of FeII and HCl may be responsible for the observed FeII oxidation. The use of strictly anoxic conditions for Fe extraction by HCl to obtain reliable Fe redox speciation data is therefore recommended.

scholarly journals Cross-linking experiments with the adenosine triphosphatase of sarcoplasmic reticulum

1979 ◽  
Vol 179 (1) ◽  
pp. 135-139 ◽  
Author(s):  
G M Hebdon ◽  
L W Cunningham ◽  
N M Green
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Adenosine Triphosphatase ◽  
Room Temperature ◽  
Cross Linking ◽  
Complete Oxidation ◽  
Thiol Groups ◽  
High Concentration ◽  
Disulphide Bonds ◽  
Dimethyl Suberimidate ◽  
Very High

The proteins of sarcoplasmic reticulum were cross-linked by rapid oxidation of thiol groups with I2. About two-thirds of the thiols were oxidized without any significant cross-linking, implying an extensive formation of intramolecular disulphide bonds. When the thiols were completely oxidized at room temperature a series of oligomers containing up to five molecules were observed, as well as large aggregates which were excluded from the gels. Complete oxidation at -10 degrees C left most of the ATPase (adenosine triphosphatase) as monomer. Similar results were obtained when copper-phenanthroline complexes or dimethyl suberimidate were used as cross-linking reagents. We conclude that most of the cross-linked species arise by linking of randomly colliding ATPase molecules which are present in the membrane at very high concentration.

Preparation of Surface Modified Fe3O4 Nanostructures via Inverse Micelle Method and Study of their Magnetic Properties for Biological Applications

2012 ◽  
Vol 21 ◽  
pp. 37-42 ◽  
Author(s):  
M.S. Sadjadi ◽  
A. Sharafi ◽  
Nazanin Farhadyar
Keyword(s):  
Magnetic Properties ◽  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Room Temperature ◽  
Superparamagnetic Iron Oxide ◽  
Fast Response ◽  
Oxide Nanoparticles ◽  
Silica Surface Modification ◽  
Average Size ◽  
Surface Modified

In this work, we report on the synthesis of superparamagnetic iron oxide nanoparticles at room temperature using microemulsion template phase consisting of cyclohexane, water, CTAB as cationic surfactant and butanol as a cosurfactant. Silica surface modification of the as-prepared nanoparticles was performed by adding TEOS directly to the alkaline medium. The structure, morphology, and magnetic properties of the products were characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) at room temperature. The results revealed formation of iron oxide nanoparticles, with an average size of 8.8-12 nm, a superparamagnetism behavior with fast response to applied magnetic fields and zero remanence and coercivity.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

Ground water quality of selected areas of Punjab and Sind Provinces, Pakistan: Chemical and microbiological aspects

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Ionic Concentration ◽  
Chloride Ions ◽  
Potassium Ions ◽  
Ammonium Ions ◽  
High Concentration ◽  
Phosphate Ions ◽  
Sodium Magnesium ◽  
Very High ◽  
Microbiological Aspects

The assessment of groundwater is essential for the estimation of suitability of water for safe use. An attempt has been made to study the groundwater of selected areas of Punjab (Sheikhupura & Sahiwal) and Sindh (Sindh, Jawar Dharki and Dharki), Pakistan. The results indicate that pH, color and odor were all within limits of WHO that is pH ranges 6.5–8.5, colorless and odorless, respectively. The high values of suspended solids were observed in the Sindh-1 and Dharki samples. Microbiologically only Sahiwal and Jawar Dharki were found fit for drinking purpose. Trace metals analysis of Sheikhupura-1 and Sindh-1 showed that values do not fall within limits of WHO for Iron. The ionic concentration analysis showed that high bicarbonate (HCO3-), ions are present in the samples of Sahiwal and Dharki; Sindh-1 and Jawar Dharki samples showed very high concentration for chloride ions, all samples were satisfactory level for sulphate (SO42-), sodium, magnesium and phosphate ions except samples of Sindh-1 and Jawar Dharki. High concentration of calcium and potassium ions was observed in samples of Sindh-1, while all other samples were found fit for drinking purposes in respect of nitrate, nitrite and ammonium ions. The high concentration of Fluoride was found only in Sheikhupura-2 samples.

scholarly journals Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1023 ◽  
Author(s):  
Ashish Chhaganlal Gandhi ◽  
Chia-Liang Cheng ◽  
Sheng Yun Wu
Keyword(s):  
Room Temperature ◽  
Excess Oxygen ◽  
Ambient Atmosphere ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Band Emission ◽  
Oxygen Ion ◽  
Integrated Intensity ◽  
Effect Of Oxygen

We report the synthesis of room temperature (RT) stabilized γ–Bi2O3 nanoparticles (NPs) at the expense of metallic Bi NPs through annealing in an ambient atmosphere. RT stability of the metastable γ–Bi2O3 NPs is confirmed using synchrotron radiation powder X-ray diffraction and Raman spectroscopy. γ–Bi2O3 NPs exhibited a strong red-band emission peaking at ~701 nm, covering 81% integrated intensity of photoluminescence spectra. Our findings suggest that the RT stabilization and enhanced red-band emission of γ‒Bi2O3 is mediated by excess oxygen ion vacancies generated at the octahedral O(2) sites during the annealing process.

scholarly journals Near quantitative synthesis of urea macrocycles enabled by bulky N-substituent

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yingfeng Yang ◽  
Hanze Ying ◽  
Zhixia Li ◽  
Jiang Wang ◽  
Yingying Chen ◽  
...  
Keyword(s):  
High Efficiency ◽  
Molecular Structures ◽  
High Yield ◽  
Kinetic Control ◽  
High Concentration ◽  
Weak Association ◽  
Quantitative Synthesis ◽  
Thermodynamic Stabilization ◽  
Discrete Structures ◽  
Very High

AbstractMacrocycles are unique molecular structures extensively used in the design of catalysts, therapeutics and supramolecular assemblies. Among all reactions reported to date, systems that can produce macrocycles in high yield under high reaction concentrations are rare. Here we report the use of dynamic hindered urea bond (HUB) for the construction of urea macrocycles with very high efficiency. Mixing of equal molar diisocyanate and hindered diamine leads to formation of macrocycles with discrete structures in nearly quantitative yields under high concentration of reactants. The bulky N-tert-butyl plays key roles to facilitate the formation of macrocycles, providing not only the kinetic control due to the formation of the cyclization-promoting cis C = O/tert-butyl conformation, but also possibly the thermodynamic stabilization of macrocycles with weak association interactions. The bulky N-tert-butyl can be readily removed by acid to eliminate the dynamicity of HUB and stabilize the macrocycle structures.

scholarly journals Properties of Silicone Rubber-Based Composites Reinforced with Few-Layer Graphene and Iron Oxide or Titanium Dioxide

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1550
Author(s):  
Vineet Kumar ◽  
Anuj Kumar ◽  
Minseok Song ◽  
Dong-Joo Lee ◽  
Sung-Soo Han ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Titanium Dioxide ◽  
Iron Oxide ◽  
Stress Relaxation ◽  
Silicone Rubber ◽  
Room Temperature ◽  
Relaxation Rates ◽  
Layer Graphene ◽  
Few Layer Graphene ◽  
Mechanical Actuation

The increasing demand for polymer composites with novel or improved properties requires novel fillers. To meet the challenges posed, nanofillers such as graphene, carbon nanotubes, and titanium dioxide (TiO2) have been used. In the present work, few-layer graphene (FLG) and iron oxide (Fe3O4) or TiO2 were used as fillers in a room-temperature-vulcanized (RTV) silicone rubber (SR) matrix. Composites were prepared by mixing RTV-SR with nanofillers and then kept for vulcanization at room temperature for 24 h. The RTV-SR composites obtained were characterized with respect to their mechanical, actuation, and magnetic properties. Fourier-transform infrared spectroscopy (FTIR) analysis was performed to investigate the composite raw materials and finished composites, and X-ray photoelectron spectroscopy (XPS) analysis was used to study composite surface elemental compositions. Results showed that mechanical properties were improved by adding fillers, and actuation displacements were dependent on the type of nanofiller used and the applied voltage. Magnetic stress-relaxation also increased with filler amount and stress-relaxation rates decreased when a magnetic field was applied parallel to the deformation axes. Thus, this study showed that the inclusion of iron oxide (Fe3O4) or TiO2 fillers in RTV-SR improves mechanical, actuation, and magnetic properties.

Small-volume vitrification and rapid warming yield high survivals of one-cell rat embryos in cryotubes

2021 ◽  
Author(s):  
Yasuyoshi Fukuda ◽  
Misako Higashiya ◽  
Takahiro Obata ◽  
Keita Basaki ◽  
Megumi Yano ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Small Volume ◽  
Sucrose Solution ◽  
High Concentration ◽  
Rat Embryos ◽  
Low Concentrations ◽  
Intracellular Ice Formation ◽  
Intracellular Ice ◽  
Warming Rate ◽  
Very High

Abstract To cryopreserve cells, it is essential to avoid intracellular ice formation during cooling and warming. One way to achieve this is to convert the water inside the cells into a non-crystalline glass. It is currently believed that to accomplish this vitrification, the cells must be suspended in a very high concentration (20–40%) of a glass-inducing solute, and subsequently cooled very rapidly. Herein, we report that this belief is erroneous with respect to the vitrification of one-cell rat embryos. In the present study, one-cell rat embryos were vitrified with 5 μL of EFS10 (a mixture of 10% ethylene glycol, 27% Ficoll, and 0.45 M sucrose) in cryotubes at a moderate cooling rate, and warmed at various rates. Survival was assessed according to the ability of the cells to develop into blastocysts and to develop to term. When embryos were vitrified at a 2,613 °C/min cooling rate and thawed by adding 1 mL of sucrose solution (0.3 M, 50 °C) at a warming rate of 18,467 °C/min, 58.1 ± 3.5% of the EFS10-vitrified embryos developed into blastocysts, and 50.0 ± 4.7% developed to term. These rates were similar to those of non-treated intact embryos. Using a conventional cryotube, we achieved developmental capabilities in one-cell rat embryos by rapid warming that were comparable to those of intact embryos, even using low concentrations (10%) of cell-permeating cryoprotectant and at low cooling rates.

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