Novel Hierarchical YBO3 :Eu3+ Nanocrystals Synthesized by Folic Acid Assisted Hydrothermal Process

MRS Advances ◽  
2019 ◽  
Vol 5 (31-32) ◽  
pp. 1661-1670
Author(s):  
Xianj. Xing ◽  
Shan Li ◽  
Yuq. Song ◽  
Yingz. Ge ◽  
Xuef. Zhang ◽  
...  
Keyword(s):  
Folic Acid ◽  
Self Assembly ◽  
Growth Process ◽  
Ph Value ◽  
Hydrothermal Process ◽  
Photoluminescence Intensity ◽  
Capping Agent ◽  
Hydrothermal Route ◽  
Small Flower

ABSTRACTYBO3:Eu3+ crystals with flower-like hierarchitecture are readily synthesized through a folic acid assisted hydrothermal process using polyborate precursors in the aqueous solution. It was found that the pH value , borate/yittrium ratio and the mass of folic acid take effects on the morphology and photoluminescence emission intensity of YBO3:Eu3+ crystals. The product with the small flower-like hierarchitecture was obtained under the conditions of pH value at 9, borate/yittrium ratio at 2 and the mass of folic acid at 0.44 g, showing the strongest photoluminescence intensity. The growth process of the YBO3:Eu3+ flowers and microflowers was invesitgated based on the time-dependent experiments, which showed that the growth mechanism of the flower-like hierarchitecture follows an in situ growth rather than self-assembly process as reported previously. Such a hydrothermal route using folic acid as a capping agent may provide a green and effective method for fabricating useful and complex 3D architectures of LEDs phosphors.

Self-Recognition and Self-Assembly of Folic Acid Salts: Columnar Liquid Crystalline Polymorphism and the Column Growth Process

1994 ◽  
Vol 116 (16) ◽  
pp. 7064-7071 ◽  
Author(s):  
Federica Ciuchi ◽  
Giovanni Di Nicola ◽  
Hermann Franz ◽  
Giovanni Gottarelli ◽  
Paolo Mariani ◽  
...  
Keyword(s):  
Folic Acid ◽  
Self Assembly ◽  
Liquid Crystalline ◽  
Growth Process ◽  
Self Recognition ◽  
Crystalline Polymorphism ◽  
Acid Salts

Hydrothermal Preparation of Hydroxyapatite/Chitosan Nanocomposites via In Situ Precipitation

2007 ◽  
Vol 330-332 ◽  
pp. 405-408
Author(s):  
Xiao Ying Lu ◽  
Zh. Liu ◽  
Jie Weng
Keyword(s):  
Crystal Size ◽  
Ph Value ◽  
Hydrothermal Process ◽  
Hydrothermal Preparation ◽  
Nano Structure ◽  
Infrared Spectrometer ◽  
Ft Ir ◽  
Low Crystalline ◽  
Electronic Microscope

The cylindrical chitosan (CS)/hydroxyapatite (HA) nanocomposites were hydrothermally prepared via in situ precipitation and characterized by x-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR), thermogravimetry (TG) and scanning electronic microscope (SEM). The results show that the as-prepared products are composed of CS and low-crystalline HA phases, and some extent of interaction between CS and HA phases exists in the composites, which is greatly influenced by the temperature and pH value in the hydrothermal process. The crystal size of HA uniform-distributed in CS matrix is calculated to be no larger than 100nm while the crystallinity of CA is greatly increased in the hydrothermal process, which is beneficial to the mechanical properties of the composites. It is proposed that the nano-structure of HA/CS composite will have the better biomedical properties in the biomaterials applications.

scholarly journals A novel visible-light-driven TiO2 photocatalytic reduction for hexavalent chromium wastewater and mechanism

2021 ◽  
Author(s):  
Baoxiu Zhao ◽  
Kaixin Zhang ◽  
Yue Huang ◽  
Qi Wang ◽  
Hao Xu ◽  
...  
Keyword(s):  
Visible Light ◽  
Self Assembly ◽  
Ph Value ◽  
Sol Gel ◽  
Photocatalytic Reduction ◽  
Complex Catalyst ◽  
Acidic Aqueous Solution ◽  
Visible Light Driven ◽  
Key Steps

Abstract TiO2 photocatalyst was prepared with a sol-gel method and its characterizations were analyzed, then TiO2 photocatalytic reduction for Cr6+ was investigated in visible light irradiation and reduction mechanism were deduced lastly. Prepared TiO2 is anatase and bandgap is about 2.95 eV. Experimental results display that almost 100% Cr6+ is removed by visible-light-driven TiO2 photocatalytic reduction after 120 min when Cr2O72− initial concentration is 1.0 mg·L−1, TiO2 dosage is 1.0 g·L−1 and pH value is 3. In acidic aqueous solution, HCrO4− is the dominant existing form of Cr6+ and adsorbed by TiO2, forming a complex catalyst HCrO4−/TiO2 which wavelength enlarges to visible light zone, proved by UV-Vis DRS. Based on XPS data, it can be deduced that Cr6+ is adsorbed on the surface of TiO2 and then reduced to Cr3+in situ by photoelectrons. Self-assembly of HCrO4−/TiO2 complex catalyst and self-reduction of Cr6+in situ are the key steps to start visible-light-driven TiO2 photocatalytic reduction. Furthermore, TiO2 photocatalytic reduction for Cr6+ fits well with pseudo first-order kinetics and has potential application to treat chemical industrial wastewater.

Phase Purity Analysis and Optical Studies of Bi2O3 Nanoparticles Suitable for Photocatalytic Activity

2018 ◽  
Vol 17 (03) ◽  
pp. 1760040 ◽  
Author(s):  
M. Malligavathy ◽  
D. Pathinettam Padiyan
Keyword(s):  
Photocatalytic Activity ◽  
Separation Efficiency ◽  
Ph Value ◽  
Point Of View ◽  
Photoluminescence Intensity ◽  
X Ray Diffraction ◽  
Hydrothermal Route ◽  
Phase Purity ◽  
First Order Kinetics ◽  
Purity Analysis

Bismuth oxide was prepared using hydrothermal route and the effect of pH on the phase of Bi2O3 reported. Phase pure [Formula: see text]-Bi2O3 was prepared at the pH of 13 and its phase purity was confirmed from the X-ray diffraction pattern. At the pH of 10, 11 and 12 the hydrothermal synthesis yields Bi(OH)3, ([Formula: see text], [Formula: see text]-Bi2O3) & Bi2O4 and mixture of [Formula: see text]-Bi2O3 & Bi2O4, respectively. The optical band gaps were calculated from reflectance spectra using the Kubelka–Munk relation and the values decrease from 3.050(3) to 2.686(3) eV with the increase in pH value. Photoluminescence intensity decrease with the increase of pH value indicated the increase in the charge separation efficiency. In the application point of view, the photocatalytic activity of the samples was evaluated for methyl orange and among the four samples, [Formula: see text]-Bi2O3 degraded 67% within 4[Formula: see text]h. The degradation of dye was analyzed using pseudo first-order kinetics and the rate constant value was 0.0045(3) min[Formula: see text] with the correlation coefficient of 0.983.

Hierarchical Structures of Silicon Oxynitride Nanowires Formed by a Gallium-Catalyzed In Situ Reactive Technique

2011 ◽  
Vol 284-286 ◽  
pp. 717-721 ◽  
Author(s):  
Shi Biao Xiang ◽  
Xu Xiang
Keyword(s):  
Self Assembly ◽  
Growth Process ◽  
Silicon Oxide ◽  
Hierarchical Structures ◽  
Silicon Oxynitride ◽  
The Self ◽  
Elemental Distribution ◽  
Si Substrate ◽  
Vapor Liquid Solid Growth

Novel doughnut-like loop structures of silicon oxynitride were grown over a Si substrate via self-assembly of ordered nanowires. These hierarchical structures were formed by metallic gallium-catalyzed vapor-liquid-solid growth at high temperature under a flow of NH3gas. The product was characterized by XRD, SEM, EDS mapping and XPS techniques. XRD characterization confirms the formation of Si3N4and silicon oxynitride phases. The silicon oxynitride loop structures assembled by ordered nanowires have outer diameters of 10-14 mm and wall thickness of 2-3 mm. The nanowire bundles in a single loop exhibit a petal-like growth mode. EDS mapping verifies the elemental distribution over the structure. XPS analyses disclose the binding contribution from Si3N4, silicon oxynitride and silicon oxide. The formation mechanism of the self-assembled structures was analyzed based on the growth process.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

Probing the Dynamic Self-Assembly Behaviour of Photoswitchable Wormlike Micelles in Real Time

2018 ◽  
Author(s):  
Elaine A. Kelly ◽  
Judith E. Houston ◽  
Rachel Evans
Keyword(s):  
Real Time ◽  
Absorption Spectroscopy ◽  
Self Assembly ◽  
Uv Light ◽  
Wormlike Micelles ◽  
Tetraethylene Glycol ◽  
Light Illumination ◽  
First Time ◽  
Dependent Processes

Understanding the dynamic self-assembly behaviour of azobenzene photosurfactants (AzoPS) is crucial to advance their use in controlled release applications such as<i></i>drug delivery and micellar catalysis. Currently, their behaviour in the equilibrium <i>cis-</i>and <i>trans</i>-photostationary states is more widely understood than during the photoisomerisation process itself. Here, we investigate the time-dependent self-assembly of the different photoisomers of a model neutral AzoPS, <a>tetraethylene glycol mono(4′,4-octyloxy,octyl-azobenzene) </a>(C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>) using small-angle neutron scattering (SANS). We show that the incorporation of <i>in-situ</i>UV-Vis absorption spectroscopy with SANS allows the scattering profile, and hence micelle shape, to be correlated with the extent of photoisomerisation in real-time. It was observed that C<sub>8</sub>AzoOC<sub>8</sub>E<sub>4</sub>could switch between wormlike micelles (<i>trans</i>native state) and fractal aggregates (under UV light), with changes in the self-assembled structure arising concurrently with changes in the absorption spectrum. Wormlike micelles could be recovered within 60 seconds of blue light illumination. To the best of our knowledge, this is the first time the degree of AzoPS photoisomerisation has been tracked <i>in</i><i>-situ</i>through combined UV-Vis absorption spectroscopy-SANS measurements. This technique could be widely used to gain mechanistic and kinetic insights into light-dependent processes that are reliant on self-assembly.

In situ Time-Resolved Small-Angle X-ray Scattering Reveals the Formation Kinetics of Polyelectrolyte Complex Micelles

2019 ◽  
Author(s):  
Hao Wu ◽  
Jeffrey Ting ◽  
Siqi Meng ◽  
Matthew Tirrell
Keyword(s):  
Small Angle ◽  
Self Assembly ◽  
Electrostatic Interactions ◽  
Polyelectrolyte Complex ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Kinetics Of ◽  
Ray Scattering

We have directly observed the <i>in situ</i> self-assembly kinetics of polyelectrolyte complex (PEC) micelles by synchrotron time-resolved small-angle X-ray scattering, equipped with a stopped-flow device that provides millisecond temporal resolution. This work has elucidated one general kinetic pathway for the process of PEC micelle formation, which provides useful physical insights for increasing our fundamental understanding of complexation and self-assembly dynamics driven by electrostatic interactions that occur on ultrafast timescales.

scholarly journals Development of In Situ Self-Assembly Nanoparticles to Encapsulate Lopinavir and Ritonavir for Long-Acting Subcutaneous Injection

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 904
Author(s):  
Irin Tanaudommongkon ◽  
Asama Tanaudommongkon ◽  
Xiaowei Dong
Keyword(s):  
Sustained Release ◽  
Trough Concentration ◽  
Self Assembly ◽  
Subcutaneous Injection ◽  
Drug Loading ◽  
Entrapment Efficiency ◽  
Long Acting

Most antiretroviral medications for human immunodeficiency virus treatment and prevention require high levels of patient adherence, such that medications need to be administered daily without missing doses. Here, a long-acting subcutaneous injection of lopinavir (LPV) in combination with ritonavir (RTV) using in situ self-assembly nanoparticles (ISNPs) was developed to potentially overcome adherence barriers. The ISNP approach can improve the pharmacokinetic profiles of the drugs. The ISNPs were characterized in terms of particle size, drug entrapment efficiency, drug loading, in vitro release study, and in vivo pharmacokinetic study. LPV/RTV ISNPs were 167.8 nm in size, with a polydispersity index of less than 0.35. The entrapment efficiency was over 98% for both LPV and RTV, with drug loadings of 25% LPV and 6.3% RTV. A slow release rate of LPV was observed at about 20% on day 5, followed by a sustained release beyond 14 days. RTV released faster than LPV in the first 5 days and slower than LPV thereafter. LPV trough concentration remained above 160 ng/mL and RTV trough concentration was above 50 ng/mL after 6 days with one subcutaneous injection. Overall, the ISNP-based LPV/RTV injection showed sustained release profiles in both in vitro and in vivo studies.

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