Investigation on the stability of water-soluble ZnO quantum dots in KB cells by X-ray fluorescence and absorption methods

2011 ◽  
Vol 269 (17) ◽  
pp. 1940-1943 ◽  
Author(s):  
P. Lu ◽  
H. Zhang ◽  
T. Satoh ◽  
T. Ohkubo ◽  
A. Yamazaki ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Water Soluble ◽  
Kb Cells ◽  
X Ray ◽  
Zno Quantum Dots ◽  
The Stability ◽  
Stability Of Water

Effects of interface bonding configuration on photoluminescence of ZnO quantum dots–SiOxNy nanocomposite films

2008 ◽  
Vol 23 (4) ◽  
pp. 1155-1162 ◽  
Author(s):  
Yu-Yun Peng ◽  
Tsung-Eong Hsieh ◽  
Chia-Hung Hsu
Keyword(s):  
Quantum Dots ◽  
Nanocomposite Films ◽  
Photoemission Spectroscopy ◽  
Yellow Emission ◽  
Interface Bonding ◽  
X Ray ◽  
Hole Trapping ◽  
Radio Frequency Sputtering ◽  
Surface Polarization ◽  
Zno Quantum Dots

Nanocomposite films containing ZnO quantum dots (QDs) and SiOxNy matrix were prepared by target-attached radio frequency sputtering. Photoluminescence (PL) dominated by violet and blue emissions was observed from all ZnO QD–SiOxNy nanocomposite films with dot diameters ranging from 2.77 to 6.65 nm. X-ray photoemission spectroscopy (XPS) revealed the formation of nitrogen-correlated bonding configurations in both the SiOxNy matrix and the dot/matrix interfaces. The nitrogen-correlated configuration at the interface produced a substantial polarization effect at dot surface. The suppression of green-yellow emission observed in photoluminescence spectra of all samples was ascribed to the hole-trapping process promoted by the enhancement of the surface polarization.

scholarly journals Evidence for the stability of ultrahydrous stishovite in Earth’s lower mantle

2019 ◽  
Vol 117 (1) ◽  
pp. 184-189 ◽  
Author(s):  
Yanhao Lin ◽  
Qingyang Hu ◽  
Yue Meng ◽  
Michael Walter ◽  
Ho-Kwang Mao
Keyword(s):  
Transition Zone ◽  
Lower Mantle ◽  
Water Reservoir ◽  
Weight Percent ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mineral Components ◽  
The Stability ◽  
Stability Of Water

The distribution and transportation of water in Earth’s interior depends on the stability of water-bearing phases. The transition zone in Earth’s mantle is generally accepted as an important potential water reservoir because its main constituents, wadsleyite and ringwoodite, can incorporate weight percent levels of H2O in their structures at mantle temperatures. The extent to which water can be transported beyond the transition zone deeper into the mantle depends on the water carrying capacity of minerals stable in subducted lithosphere. Stishovite is one of the major mineral components in subducting oceanic crust, yet the capacity of stishovite to incorporate water beyond at lower mantle conditions remains speculative. In this study, we combine in situ laser heating with synchrotron X-ray diffraction to show that the unit cell volume of stishovite synthesized under hydrous conditions is ∼2.3 to 5.0% greater than that of anhydrous stishovite at pressures of ∼27 to 58 GPa and temperatures of 1,240 to 1,835 K. Our results indicate that stishovite, even at temperatures along a mantle geotherm, can potentially incorporate weight percent levels of H2O in its crystal structure and has the potential to be a key phase for transporting and storing water in the lower mantle.

scholarly journals Hydrothermal synthesis of ZnO quantum dot/KNb3O8 nanosheet photocatalysts for reducing carbon dioxide to methanol

2017 ◽  
Vol 8 ◽  
pp. 2264-2270 ◽  
Author(s):  
Xiao Shao ◽  
Weiyue Xin ◽  
Xiaohong Yin
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Uv Light ◽  
Formation Rate ◽  
X Ray Diffraction ◽  
Methanol Production ◽  
X Ray ◽  
Transmission Electron ◽  
Methanol Formation ◽  
Zno Quantum Dots

ZnO quantum dots and KNb3O8 nanosheets were synthesized by a two-step hydrothermal method for the photocatalytic reduction of CO2 to methanol where isopropanol is simultaneously oxidized to acetone . The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and UV–vis absorption spectroscopy (UV–vis). The photocatalytic activity of the materials was evaluated by formation rate of methanol under UV light irradiation at ambient temperature and pressure. The methanol formation rate of pure KNb3O8 nanosheets was found to be 1257.21 μmol/g/h, and after deposition of 2 wt % ZnO quantum dots on the surface of KNb3O8 nanosheets, the methanol production rate was found to increase to 1539.77 μmol/g/h. Thus, the ZnO quantum dots obviously prompted separation of charge carriers, which was explained by a proposed mechanism for this photocatalytic reaction.

The stability of water-soluble modified starch iodophors

2013 ◽  
Vol 63 (1) ◽  
Author(s):  
V. Navikaitė ◽  
P. P. Danilovas ◽  
R. Klimavičiūtė ◽  
J. Bendoraitienė
Keyword(s):  
Water Soluble ◽  
Modified Starch ◽  
The Stability ◽  
Stability Of Water

Synthesis and characterization of water-soluble ZnO quantum dots prepared through PEG-siloxane coating

2008 ◽  
Vol 32 (8) ◽  
pp. 1388 ◽  
Author(s):  
Ralph-Olivier Moussodia ◽  
Lavinia Balan ◽  
Raphaël Schneider
Keyword(s):  
Quantum Dots ◽  
Water Soluble ◽  
Synthesis And Characterization ◽  
Zno Quantum Dots

scholarly journals Variability of Water-Soluble Forms of Choline Concentrations in Human Milk during Storage, after Pasteurization, and among Women

Nutrients ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 3024 ◽  
Author(s):  
Sara Moukarzel ◽  
Alejandra M. Wiedeman ◽  
Lynda S. Soberanes ◽  
Roger A. Dyer ◽  
Sheila M. Innis ◽  
...  
Keyword(s):  
Human Milk ◽  
Infant Development ◽  
Sole Source ◽  
Individual Variability ◽  
Water Soluble ◽  
Total Water ◽  
Breastfed Infants ◽  
The Stability ◽  
Stability Of Water ◽  
And Storage

Choline is critical for infant development and mother’s milk is the sole source of choline for fully breastfed infants until six months of age. Human milk choline consists to 85% of water-soluble forms of choline including free choline (FC), phosphocholine (PhosC), and glycerophosphocholine (GPC). Donor milk requires safe handling procedures such as cold storage and pasteurization. However, the stability of water-soluble forms of choline during these processes is not known. The objectives of this research were to determine the effect of storage and pasteurization on milk choline concentration, and the diurnal intra- and inter-individual variability of water-soluble choline forms. Milk samples were collected from healthy women who were fully breastfeeding a full-term, singleton infant <6 months. Milk total water-soluble forms of choline, PhosC, and GPC concentrations did not change during storage at room temperature for up to 4 h. Individual and total water-soluble forms of choline concentrations did not change after storage for 24 h in the refrigerator or for up to one week in the household freezer. Holder pasteurization decreased PhosC and GPC, and thereby total water-soluble choline form concentrations by <5%. We did not observe diurnal variations in PhosC and total water-soluble forms of choline concentrations, but significant differences in FC and GPC concentrations across five sampling time points throughout one day. In conclusion, these outcomes contribute new knowledge for the derivation of evidence-informed guidelines for the handling and storage of expressed human milk as well as the development of optimized milk collection and storage protocols for research studies.

scholarly journals In Situ Preparation of Amphibious ZnO Quantum Dots with Blue Fluorescence Based on Hyperbranched Polymers and their Application in Bio-Imaging

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 144 ◽  
Author(s):  
Gaiying Lei ◽  
Shu Yang ◽  
Ranran Cao ◽  
Peng Zhou ◽  
Han Peng ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Gene Transfection ◽  
Heating Time ◽  
Water Soluble ◽  
Molar Ratio ◽  
Quantum Yields ◽  
Blue Fluorescence ◽  
In Situ Preparation ◽  
Bio Imaging ◽  
Zno Quantum Dots

A new strategy for preparing amphibious ZnO quantum dots (QDs) with blue fluorescence within hyper-branched poly(ethylenimine)s (HPEI) was proposed in this paper. By changing [Zn2+]/[OH−] molar ratio and heating time, ZnO QDs with a quantum yields (QY) of 30% in ethanol were obtained. Benefiting from the amphibious property of HPEI, the ZnO/HPEI nanocomposites in ethanol could be dissolved in chloroform and water, acquiring a QY of 53%, chloroform and 11% in water. By this strategy, the ZnO/HPEI nano-composites could be applied in not only in optoelectronics, but also biomedical fields (such as bio-imaging and gene transfection). The bio-imaging application of water-soluble ZnO/HPEI nanocomposites was investigated and it was found that they could easily be endocytosed by the COS-7 cells, without transfection reagent, and they exhibited excellent biological imaging behavior.

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