scholarly journals An Experimental Study on the Shape Changes of TiO2Nanocrystals Synthesized by Microemulsion-Solvothermal Method

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Wei Kong ◽  
Bo Liu ◽  
Bo Ye ◽  
Zhongping Yu ◽  
Hua Wang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Stainless Steel ◽  
Oleic Acid ◽  
Solvothermal Method ◽  
Shape Change ◽  
Tetrabutyl Titanate ◽  
Microemulsion System ◽  
Solvothermal Process ◽  
Shape Changes ◽  
Shape And Size

Titanium dioxide (TiO2) nanocrystals of different shape were successfully synthesized in a new microemulsion system through a solvothermal process. The TiO2nanocrystals were prepared from the reaction of tetrabutyl titanate (TBT),H2O, and oleic acid (OA), which were used as solvent and surfactant at 300∘Cand 240∘Cin a stainless steel autoclave. The sphere, polygon, and rhombus-shaped nanocrystals have been prepared at 300∘Cand the dot- and- rod shaped nanocrystals have been synthesized at 240∘C. The effect of the reaction time on the shape and size of TiO2nanocrystals in this method was studied in the present paper. The size distribution of TiO2nanocrystals prepared at 300∘Cfor different hours is also studied. In addition, an attempt to describe the mechanism of shape change of TiO2nanocrystals was presented in this paper.

Unusual Reuniting of Barium Titanate Nanoparticles

2010 ◽  
Vol 434-435 ◽  
pp. 860-862
Author(s):  
Xiao Quan Zhang ◽  
Xiao Hui Wang ◽  
Tie Yu Sun ◽  
Ai Li Cui ◽  
Long Tu Li
Keyword(s):  
Oleic Acid ◽  
Nitric Acid ◽  
Barium Titanate ◽  
Elaidic Acid ◽  
Solvothermal Method ◽  
Raw Materials ◽  
Tetrabutyl Titanate ◽  
Barium Acetate ◽  
Self Assembling ◽  
Barium Titanate Nanoparticles

A solvothermal method to synthesize barium titanate nanoparticles is employed. In this method many raw materials such as oleic acid, surfactant, sodium hydroxide, alkali barium acetate, alcohol, tetrabutyl titanate are used. When the samples are collected, oleic acid which has mush an account will cover the whole particles. To make the samples cleaner, nitric acid is used to transition oleic acid to elaidic acid which is lighter than water then it will float up to be removed. In the progress to wash off the oleic acid the particles were found to reunite unusually: bigger and cubic particles are formed and the shape seems like single crystal but they are reunitions indeed, we used HTEM to prove this. It means self–assembling might happen through the progress, the spontaneous polarization orient, polarity of molecules will affect this progess.

A Novel Intermediate-Sacrificed Route to Polycrystalline Nanorods Consisting of Highly Oriented Quantum Dots of Cubic CdS

2008 ◽  
Vol 8 (6) ◽  
pp. 3112-3116 ◽  
Author(s):  
Qi-Zhi Yao ◽  
Gu Jin ◽  
Gen-Tao Zhou ◽  
Xinchen Wang ◽  
Jimmy C. Yu
Keyword(s):  
Quantum Dots ◽  
Chemical Reactions ◽  
Solvothermal Method ◽  
Intermediate Complex ◽  
Face Centered Cubic ◽  
Solvothermal Process ◽  
Mean Diameter ◽  
Face Centered ◽  
Solvothermal Conditions ◽  
Cubic Cds

Polycrystalline nanorods of CdS were successfully prepared by a novel solvothermal method using simple initial materials of sulfur and Cd(Ac)2 ˙ 2H2O in pyridine at 160 °C. TEM, HRTEM and SAED analyses reveal that the polycrystalline nanorods with the lengths from 400 to 1000 nm and a mean diameter of ca 40 nm are assembled with highly oriented quantum dots of face-centered cubic CdS. The chemical reactions under the current solvothermal conditions involve the first reduction of sulfur by acetate anions to S2–, and subsequently the formation of intermediate complex CdS(Py)0.5 with nanorod-like morphology, as well as finally prolonged solvothermal process to the formation of the polycrystalline nanorods. Therefore, a new intermediate-sacrificed mechanism to direct the formation of cubic CdS polycrystalline nanorods was proposed.

Autonomy and non-autonomy in Drosophila mesoderm determination and morphogenesis

Development ◽  
1994 ◽  
Vol 120 (4) ◽  
pp. 853-859 ◽  
Author(s):  
M. Leptin ◽  
S. Roth
Keyword(s):  
Cell Shape ◽  
Shape Change ◽  
Developmental Program ◽  
Cell Shape Change ◽  
Ventral Furrow ◽  
Large Numbers ◽  
The Individual ◽  
Mutant Cells ◽  
Transplantation Experiments ◽  
Shape Changes

The mesoderm in Drosophila invaginates by a series of characteristic cell shape changes. Mosaics of wild-type cells in an environment of mutant cells incapable of making mesodermal invaginations show that this morphogenetic behaviour does not require interactions between large numbers of cells but that small patches of cells can invaginate independent of their neighbours' behaviour. While the initiation of cell shape change is locally autonomous, the shapes the cells assume are partly determined by the individual cell's environment. Cytoplasmic transplantation experiments show that areas of cells expressing mesodermal genes ectopically at any position in the egg form an invagination. We propose that ventral furrow formation is the consequence of all prospective mesodermal cells independently following their developmental program. Gene expression at the border of the mesoderm is induced by the apposition of mesodermal and non-mesodermal cells.

scholarly journals Theoretical and Experimental Study of Ultrasonic Vibration-Assisted Laser Polishing 304 Stainless Steel

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 206146-206163
Author(s):  
Di Kang ◽  
Ping Zou ◽  
Hao Wu ◽  
Wenjie Wang ◽  
Jilin Xu
Keyword(s):  
Experimental Study ◽  
Stainless Steel ◽  
Ultrasonic Vibration ◽  
304 Stainless Steel ◽  
Laser Polishing

Compaction-related deformation in Cambrian olenelloid trilobites and its implications for fossil morphometry

1999 ◽  
Vol 73 (2) ◽  
pp. 355-371 ◽  
Author(s):  
Mark Webster ◽  
Nigel C. Hughes
Keyword(s):  
Lower Cambrian ◽  
Shape Change ◽  
Anterior Lobe ◽  
Interspecific Differences ◽  
Fracture Patterns ◽  
Morphometric Analyses ◽  
Ontogenetic Trajectories ◽  
Metric Distances ◽  
Relative Convexity ◽  
Shape Changes

Morphometric analyses of silicified and nonsilicified (preserved in shale) specimens of the olenelloid trilobites Olenellus (Olenellus) gilberti Meek (in White, 1874) and Nephrolenellus geniculatus Palmer, 1998, from the Lower Cambrian C-Shale Member of the Pioche Formation show that even well-preserved specimens in shales have undergone significant changes in lateral as well as vertical dimensions as a result of compaction. Analyses of cephalic landmarks show that in both species compaction causes posteriordirected collapse of the anterior lobe of the glabella, adaxial deformation of the ocular lobes, and abaxial and anterior splaying of genal regions. These shape changes are explicable in terms of observed exoskeletal fracture patterns. Landmarks show an increase in scatter around their ontogenetic trajectories that is generally proportional to the degree of lateral shift each landmark has undergone. Interspecific differences in compactional response may depend on the relative convexity of the cephalon. Olenellus (Olenellus) gilberti is a low-convexity species and shows marked lateral shape change, particularly in the genal region. Nephrolenellus geniculatus is more convex and shows less severe lateral shape change. Landmarks of both species exhibit an average trebling of the degree of scatter around their average ontogenetic trajectories in compacted samples. Because even well-preserved specimens in shales differ in shape from their precompactional appearance, results of morphometric studies utilizing metric distances between landmarks in trilobites where compaction can be detected must be interpreted with caution.

scholarly journals Preparation of N-TiO2/SiO2 composites by solvothermal method and their photocatalytic properties

2022 ◽  
Author(s):  
Chunli Wu ◽  
Xiaohao Dong ◽  
Lan Wang ◽  
Lei Zhang ◽  
Xiaotong Liu
Keyword(s):  
Nitric Acid ◽  
Energy Level ◽  
Visible Light ◽  
Solvothermal Method ◽  
Synthesis Method ◽  
Volume Ratio ◽  
Tetrabutyl Titanate ◽  
Characterization Methods ◽  
Long Term Stability ◽  
Photoelectric Properties

Abstract In order to improve the visible light catalytic activity of titanium dioxide (TiO2) and ensure its long-term stability on the surface of concrete, an N-TiO2/SiO2 composite was prepared using tetrabutyl titanate, nitric acid, and modified SiO2 nanospheres as the precursors by a solvothermal method. The effect of nitric acid on the phase composition, morphology and photoelectric properties of the synthesized photocatalytic composites was systematically studied by various characterization methods. The results show that the optimum nitric acid/butyl titanate volume ratio is 1/6. The nitrogen-doped TiO2 nanoparticles were uniformly dispersed on the surface of spherical SiO2 with a diameter of 200 nm. The degradation rate of simulated pollutants (RhB) with pH 5 and 7 exceeded 95% within 30 minutes and the catalytic effect remained excellent after five repetitions without much weakening. The excellent visible photocatalytic performance can be attributed to the doping of N replacing part of the oxygen atoms in TiO2, forming the energy level of N 2p at the O 2p energy level and reducing the TiO2 energy band gap to 2.99 eV. At the same time, the better dispersion of N-TiO2/SiO2 prepared by this new synthesis method also plays an important role in the improvement of visible light photocatalytic activity.

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