Search results for "Chemicals"
showing 10 items of 991 documents
Hydrothermally Synthesized Strontium Peroxyapatite
2015
The current research focuses on peroxide ion incorporation in the structure of strontium hydroxyapatite (SrHAp) by exposure to H2O2 ina closed hydrothermal vessel under mild conditions at 130 to 170 °C. Peroxide enriched strontium apatite (SrPerAp) was characterized for structure by X-Ray diffraction, for peroxide content- by permanganometric titration and then viewed by SEM. This study continued from previous work that used 30%H2O2 and showed a higher included peroxide content after processing with 50% H2O2 at 130 °C 70% of the theoretical peroxide content in apatitic channels of strontium apatite. This is the highest peroxide content incorporated to date and employs a lower temperature th…
Effect of Mg2+ ions on competitive metal ions adsorption/desorption on magnesium ferrite : mechanism, reusability and stability studies
2021
The adsorption behavior of magnesium ferrite in single- and multicomponent metal ions solutions in the presence of Mg2+ ions were studied. A dramatic decrease in the adsorption capacity of magnesium ferrite towards Mn2+, Co2+, and Ni2+ ions for comparison study of single- and multicomponent solutions was established. The affinity of the sorbent in accordance with the maximum sorption capacities increases in the following order Cu2+ > Co2+ > Ni2+ > Mn2+. High efficiency of magnesium ferrite regeneration (~100%) with aqueous solutions of magnesium chloride in the concentration range of 0.001-0.1 M was shown. The low degree of toxic metal ions desorption combined with XRD, IR spectroscopy, and…
Effective Recovery Process of Copper from Waste Printed Circuit Boards Utilizing Recycling of Leachate
2020
AbstractThis study presents an optimized leaching and electrowinning process for the recovery of copper from waste printed circuit boards including studies of chemical consumption and recirculation of leachate. Optimization of leaching was performed using response surface methodology in diluted sulfuric acid and hydrogen peroxide media. Optimum leaching conditions for copper were found by using 3.6 mol L−1 sulfuric acid, 6 vol.% hydrogen peroxide, pulp density of 75 g L−1 with 186 min leaching time at 20°C resulting in complete leaching of copper followed by over 92% recovery and purity of 99.9% in the electrowinning. Study of chemical consumption showed total decomposition of hydrogen pero…
Protected but Accessible: Oxygen Activation by a Calixarene-Stabilized Undecagold Cluster
2013
DFT computations show that calixarenes stabilize subnanometer Au11 clusters allowing access of small molecules like O2 to reactive metal sites in the core. Maximum of three dioxygen molecules can bind to the cluster, and they are activated to a superoxo O2(-) state. This study predicts that gold clusters could act as viable oxidation catalysts at ambient conditions based on similar principles as the metal centers in enzymes.
Novel supramolecular affinity materials based on (−)-isosteviol as molecular templates
2013
The readily available ex-chiral-pool building block (−)-isosteviol was combined with the C3-symmetric platforms hexahydroxytriphenylene and hexaaminotriptycene providing large and rigid molecular architectures. Because of the persistent cavities these scaffolds are very potent supramolecular affinity materials for head space analysis by quartz crystal microbalances. The scaffolds serve in particular as templates for tracing air-borne arenes at low concentration. The affinities of the synthesized materials towards different air-borne arenes were determined by 200 MHz quartz crystal microbalances.
"Table 15" of "Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in $pp$ collisions at $\sqrt{s} =13$ TeV w…
2020
Observed top-quark mass distribution and expected background in Region SR2 Tight 2b after the fit (Post-Fit) under the background-only hypothesis for the boosted analysis.
"Table 12" of "Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in $pp$ collisions at $\sqrt{s} =13$ TeV w…
2020
Observed top-quark mass distribution and expected background in Region SR2 Medium 1b after the fit (Post-Fit) under the background-only hypothesis for the boosted analysis.
"Table 14" of "Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in $pp$ collisions at $\sqrt{s} =13$ TeV w…
2020
Observed top-quark mass distribution and expected background in Region SR2 Tight 1b after the fit (Post-Fit) under the background-only hypothesis for the boosted analysis.
"Table 13" of "Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in $pp$ collisions at $\sqrt{s} =13$ TeV w…
2020
Observed top-quark mass distribution and expected background in Region SR2 Medium 2b after the fit (Post-Fit) under the background-only hypothesis for the boosted analysis.
Synthese mehrerer polymerhomologer reihen von diol-oligo-urethanen. Synthese von makromolekeln einheitlicher größe. V. Mitt.
1961
Mit Hilfe des Duplikationsverfahrens und durch schrittweise Synthese werden mehrere polymerhomologe Reihen von Diol-oligo-urethanen synthetisiert. Die Anwendbarkeit dieser Methode wird eingehend diskutiert. Die Diol-oligo-urethane werden durch Endgruppenanalyse charakterisiert. Several homologous polymeric series of diol-oligo-urethanes are prepared by the method of duplication and by synthesis step by step. The application of these methods is discussed thoroughly. The diol-oligo-urethanes are characterized by end-group analysis.