Preparation of nano-t-Se with different particle sizes and particle size dependence of the melting thermodynamics

CrystEngComm ◽  
2019 ◽  
Vol 21 (37) ◽  
pp. 5650-5657
Author(s):  
Hongxing Li ◽  
Xinru Song ◽  
Xing Yu ◽  
Jianhua Zhang ◽  
Zixiang Cui ◽  
...  
Keyword(s):  
Particle Size ◽  
Size Dependence ◽  
Particle Sizes ◽  
Melting Thermodynamics ◽  
Different Diameters

Spherical nano-selenium of different diameters was prepared and the particle size dependence of the melting thermodynamics of nano-selenium was explored.

SIZE-DEPENDENCE OF INFRARED SPECTRA IN NIOBIUM CARBIDE NANOCRYSTALS

2012 ◽  
Vol 23 (08) ◽  
pp. 1240001 ◽  
Author(s):  
V. ALVIN SHUBERT ◽  
STEVEN P. LEWIS
Keyword(s):  
Density Functional Theory ◽  
Particle Size ◽  
Density Functional ◽  
Size Dependence ◽  
Niobium Carbide ◽  
Structural Features ◽  
Particle Sizes ◽  
Vibrational Modes ◽  
Functional Theory ◽  
Ir Spectroscopic

Niobium carbide nanocrystals of ~1:1 stoichiometry have recently been observed for particle sizes ranging from Nb4C4 to Nb50C50 . Infrared (IR) spectroscopic measurements show that a new band of IR vibrational modes appears with increasing particle size at Nb9C9 . Using density-functional theory, we show that the vibrational modes in the new band involve structural features present only in nanocrystals with three or more atomic layers in every direction. The Nb9C9 nanocrystal is right at this structural threshold.

scholarly journals Particle Size Dependence of TiO2Electrodes in Rechargeable Lithium Battery

1996 ◽  
Vol 19 (3) ◽  
pp. 189-198 ◽  
Author(s):  
S. Y. Huang ◽  
G. Campet ◽  
N. Treuil ◽  
J. Porter ◽  
K. Chhor
Keyword(s):  
Particle Size ◽  
Lithium Battery ◽  
Size Dependence ◽  
Storage Capacity ◽  
Xrd Analysis ◽  
Structural Defects ◽  
Particle Sizes ◽  
Nanosized Particles ◽  
Rechargeable Lithium Battery ◽  
Surface Areas

Particle size effects in five anatase TiO2pellet electrodes with different particle sizes (4 ∼ 300nm) and surface areas (8 ∼ 380m2/g) were studied by XRD analysis, chronopotentiometry and chronoamperometry in Li/LiN(CF3SO2)2+ EC:DME/TiO2cells. Nanosized TiO2electrodes showed by 22% larger storage capacity, 50% lower overvoltage loss at the same current density, and 75% higher charge density for a given time than microsized ones; electric storage capacity enhances more rapidly with decreasing particle size and increasing surface area in a nanoscale region than in a microscale region. The particle size dependence may be explained by surface morphology of electrodes and existence of structural defects or distortion in the surface layer of TiO2nanosized particles.

SIZE-DEPENDENT EQUATION OF STATE FOR NANOMATERIALS

2012 ◽  
Vol 11 (01) ◽  
pp. 1250010
Author(s):  
ARCHANA BHATT ◽  
MUNISH KUMAR
Keyword(s):  
Particle Size ◽  
Equation Of State ◽  
Size Dependence ◽  
Theoretical Method ◽  
Particle Sizes ◽  
Isothermal Compression ◽  
Compression Curve ◽  
Size Dependent ◽  
Theory And Experiment ◽  
Good Agreement

Simple theoretical method is developed to study the size dependence of equation of state of nanomaterials. The isothermal compression of Ni and ε- Fe has been computed for different particle sizes. A shift in compression curve is obtained by increasing the particle size. This demonstrates the softening of the material by increasing the particle size. For larger particle size (~100 nm) the compression curve resembles with that of the bulk. This demonstrates that the nanomaterial becomes bulk for larger particle size. The results have been compared with the available experimental data. A good agreement between theory and experiment demonstrates the validity of the method proposed in the present paper.

Surface energy of cellulosic materials: The effect of particle morphology, particle size, and hydroxyl number

TAPPI Journal ◽  
2015 ◽  
Vol 14 (9) ◽  
pp. 565-576 ◽  
Author(s):  
YUCHENG PENG ◽  
DOUGLAS J. GARDNER
Keyword(s):  
Particle Size ◽  
Surface Energy ◽  
Particle Morphology ◽  
Nanofibrillated Cellulose ◽  
Particle Sizes ◽  
Hydroxyl Number ◽  
Small Individual ◽  
Dispersion Component ◽  
Commercial Applications ◽  
Lower Temperature

Understanding the surface properties of cellulose materials is important for proper commercial applications. The effect of particle size, particle morphology, and hydroxyl number on the surface energy of three microcrystalline cellulose (MCC) preparations and one nanofibrillated cellulose (NFC) preparation were investigated using inverse gas chromatography at column temperatures ranging from 30ºC to 60ºC. The mean particle sizes for the three MCC samples and the NFC sample were 120.1, 62.3, 13.9, and 9.3 μm. The corresponding dispersion components of surface energy at 30°C were 55.7 ± 0.1, 59.7 ± 1.3, 71.7 ± 1.0, and 57.4 ± 0.3 mJ/m2. MCC samples are agglomerates of small individual cellulose particles. The different particle sizes and morphologies of the three MCC samples resulted in various hydroxyl numbers, which in turn affected their dispersion component of surface energy. Cellulose samples exhibiting a higher hydroxyl number have a higher dispersion component of surface energy. The dispersion component of surface energy of all the cellulose samples decreased linearly with increasing temperature. MCC samples with larger agglomerates had a lower temperature coefficient of dispersion component of surface energy.

scholarly journals Effect of particle size on phytochemical composition and antioxidant properties of Sargassum cristaefolium ethanol extract

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. S. Prasedya ◽  
A. Frediansyah ◽  
N. W. R. Martyasari ◽  
B. K. Ilhami ◽  
A. S. Abidin ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Particle Size ◽  
Antioxidant Activities ◽  
Antioxidant Properties ◽  
Ethanol Extract ◽  
Total Phenolic ◽  
Particle Sizes ◽  
Epicatechin Gallate ◽  
Particle Size Reduction ◽  
Phytochemical Composition

AbstractSample particle size is an important parameter in the solid–liquid extraction system of natural products for obtaining their bioactive compounds. This study evaluates the effect of sample particle size on the phytochemical composition and antioxidant activity of brown macroalgae Sargassum cristaefolium. The crude ethanol extract was extracted from dried powders of S.cristeafolium with various particle sizes (> 4000 µm, > 250 µm, > 125 µm, > 45 µm, and < 45 µm). The ethanolic extracts of S.cristaefolium were analysed for Total Phenolic Content (TPC), Total Flavonoid Content (TFC), phenolic compound concentration and antioxidant activities. The extract yield and phytochemical composition were more abundant in smaller particle sizes. Furthermore, the TPC (14.19 ± 2.08 mg GAE/g extract to 43.27 ± 2.56 mg GAE/g extract) and TFC (9.6 ± 1.8 mg QE/g extract to 70.27 ± 3.59 mg QE/g extract) values also significantly increased as particle sizes decreased. In addition, phenolic compounds epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and Epigallocatechin gallate (EGCG) concentration were frequently increased in samples of smaller particle sizes based on two-way ANOVA and Tukey’s multiple comparison analysis. These results correlate with the significantly stronger antioxidant activity in samples with smaller particle sizes. The smallest particle size (< 45 µm) demonstrated the strongest antioxidant activity based on DPPH, ABTS, hydroxyl assay and FRAP. In addition, ramp function graph evaluates the desired particle size for maximum phytochemical composition and antioxidant activity is 44 µm. In conclusion, current results show the importance of particle size reduction of macroalgae samples to increase the effectivity of its biological activity.

scholarly journals Experimental Analysis of the Mechanical Properties and Resistivity of Tectonic Coal Samples with Different Particle Sizes

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2303
Author(s):  
Congyu Zhong ◽  
Liwen Cao ◽  
Jishi Geng ◽  
Zhihao Jiang ◽  
Shuai Zhang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Coalbed Methane ◽  
Coal Sample ◽  
Fine Particles ◽  
Particle Sizes ◽  
Tectonic Coal

Because of its weak cementation and abundant pores and cracks, it is difficult to obtain suitable samples of tectonic coal to test its mechanical properties. Therefore, the research and development of coalbed methane drilling and mining technology are restricted. In this study, tectonic coal samples are remodeled with different particle sizes to test the mechanical parameters and loading resistivity. The research results show that the particle size and gradation of tectonic coal significantly impact its uniaxial compressive strength and elastic modulus and affect changes in resistivity. As the converted particle size increases, the uniaxial compressive strength and elastic modulus decrease first and then tend to remain unchanged. The strength of the single-particle gradation coal sample decreases from 0.867 to 0.433 MPa and the elastic modulus decreases from 59.28 to 41.63 MPa with increasing particle size. The change in resistivity of the coal sample increases with increasing particle size, and the degree of resistivity variation decreases during the coal sample failure stage. In composite-particle gradation, the proportion of fine particles in the tectonic coal sample increases from 33% to 80%. Its strength and elastic modulus increase from 0.996 to 1.31 MPa and 83.96 to 125.4 MPa, respectively, and the resistivity change degree decreases. The proportion of medium particles or coarse particles increases, and the sample strength, elastic modulus, and resistivity changes all decrease.

scholarly journals Investigation of the kinetics of spontaneous combustion of the major coal seam in Dahuangshan mining area of the Southern Junggar coalfield, Xinjiang, China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Li Shen ◽  
Qiang Zeng
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Coal Seam ◽  
Spontaneous Combustion ◽  
Heating Temperature ◽  
Characteristic Temperature ◽  
Mining Area ◽  
Particle Sizes ◽  
Coal Oxidation ◽  
Increasing Temperature

AbstractIn the present paper, with using diverse methods (including the SEM, the XRD, the TPO, the FTIR, and the TGA) , the authors analysed samples of the major coal seam in Dahuangshan Mining area with different particle sizes and with different heated temperatures (from 50 to 800 °C at regular intervals of 50 °C). The results from SEM and XRD showed that high temperature and high number of pores, fissures, and hierarchical structures in the coal samples could facilitate oxidation reactions and spontaneous combustion. A higher degree of graphitization and much greater number of aromatic microcrystalline structures facilitated spontaneous combustion. The results from TPO showed that the oxygen consumption rate of the coal samples increased exponentially with increasing temperature. The generation rates of different gases indicated that temperatures of 90 °C or 130 °C could accelerate coal oxidation. With increasing temperature, the coal oxidation rate increased, and the release of gaseous products was accelerated. The FTIR results showed that the amount of hydroxide radicals and oxygen-containing functional groups increased with the decline in particle size, indicating that a smaller particle size may facilitate the oxidation reaction and spontaneous combustion of coal. The absorbance and the functional group areas at different particle sizes were consistent with those of the heated coal samples, which decreased as the temperature rose. The results from TGA showed that the characteristic temperature T3 declined with decreasing particle size. After the sample with 0.15–0.18 mm particle size was heated, its carbon content decreased, and its mineral content increased, inhibiting coal oxidation. This result also shows that the activation energy of the heated samples tended to increase at the stage of high-temperature combustion with increasing heating temperature.

Effects of Particles Size of Nanosilica on Properties of Polybenzoxazine Nanocomposites

2015 ◽  
Vol 659 ◽  
pp. 394-398 ◽  
Author(s):  
Nutthaphon Liawthanyarat ◽  
Sarawut Rimdusit
Keyword(s):  
Particle Size ◽  
Silica Nanoparticles ◽  
Primary Particle ◽  
Mechanical And Thermal Properties ◽  
Particle Sizes ◽  
Barrier Effect ◽  
Degradation Temperature ◽  
Maximum Value ◽  
Wetting Behaviors ◽  
Composite Samples

Polybenzoxazine nanocomposites filled with three different sizes of silica nanoparticles are investigated for their mechanical and thermal properties. In this research, silica nanoparticles with primary particle sizes of 7, 14 and 40 nm were incorporated in polybenzoxazine matrix at a fixed content of 3% by weight. From the experimental results, the storage modulus of the polybenzoxazine nanocomposite was found to systematically increase with decreasing the particle sizes of nanosilica suggesting better reinforcement of the smaller particles. Glass transition temperature was found to slightly increase with the addition of the silica nanoparticles. The uniformity of the composite samples were also evaluated by thermogravimetric analysis to show good dispersion of the silica nanoparticles in the composite samples as a result of high processability of the benzoxazine resin used i.e. low A-stage viscosity with good wetting behaviors. Degradation temperature at 5% weight loss (Td,5) of polybenzoxazine nanocomposites filled with different particle sizes of silica nanoparticles was found to increase from the value of 325 °C of the neat polybenzoxazine to the maximum value of about 340 °C with an addition of the nanosilica of the smallest particle size used. Finally, the smaller nanosilica particle size was also found to show more pronounced effect on Td,5enhancement of the composite samples as a result of greater barrier effect from larger surface area of the smaller particles.

Effect of Particle Size on the Oil Yield and Catechin Compound Using Accelerated Solvent Extraction

2013 ◽  
Vol 60 (1) ◽  
Author(s):  
Mohd Azizi Che Yunus ◽  
Manzurudin Hasan ◽  
Norasikin Othman ◽  
Siti Hamidah Mohd-Setapar ◽  
Liza Md.-Salleh ◽  
...  
Keyword(s):  
Particle Size ◽  
Solvent Extraction ◽  
Accelerated Solvent Extraction ◽  
Extraction Time ◽  
Oil Yield ◽  
Particle Sizes ◽  
Experimental Range ◽  
Areca Catechu ◽  
Effect Of Particle Size ◽  
Extraction Cycle

Kajian ini bertujuan untuk mengkaji kesan saiz zarah ke atas pengekstrakan sebatian catechin daripada biji Areca catechu L. dengan menggunakan Pengekstrakan Pelarut Terpecut (PPT). Saiz zarah biji Areca catechu dipelbagaikan dari 75 μm sehingga 500 μm. Pengekstrakan telah dijalankan padaparameter tetap iaitu suhu (140oC), tekanan (1500 psi), masa (10 minit), isipadu semburan (60%) dan satu kitaran pengekstrakan, masing-masing. Hasil minyak peratusan yang lebih tinggi adalah 300 mg minyak / gram sampel (30.00% pati minyak) ditemui pada 125 μm. Walaubagaimanapun, kandungan catechin dalam pati minyak hanya 0.0375 mg catechin / gram sampel. Saiz zarah yang terbaik dalam julat uji kaji ini telah dikenal pasti pada 500 μm yang memberikan kandungan catechin yang tinggi iaitu 0.0515 mg catechin / gram sampel dari 247.5 mg minyak / gram sampel (24.75% pati minyak). Kata kunci: Saiz zarah; catechin; LC-MS-TOF; pengekstrakan pelarut terpecut The purpose of this work is to investigate the effects of particle size on the extraction of catechincompound from Areca catechu L. seeds by using Accelerated Solvent Extraction (ASE). The particle sizes of Areca catechu L. seeds are varied from 75 µm until 500 µm. The extraction is conducted at fixed parameters which are temperature (140oC), pressure (1500 psi), extraction time (10 minutes), flush volume (60%) and the static cycle is done for 1 extraction cycle respectively. Higher percentage oil yield of 300mg oil/gram of sample (30.00% oil yield) is found at 125 µm. However, the amount of catechin in oil yields is only 0.0375 mg of catechin/gram of sample. The best of particle size within the experimental range has been identified at 500 µm which gives a high content of catechin with 0.0515 mg Catechin/gram of sample from 247.5 mg oil/gram of sample (24.75% oil yield). Keywords: Particle size; catechin; LC-MS-TOF; accelerated solvent extraction

scholarly journals Space Charge Property of Polyethylene/Silica Nanocomposites at Different Elongations

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Can Wang ◽  
Youyuan Wang ◽  
Peng Fan ◽  
Ruijin Liao
Keyword(s):  
Particle Size ◽  
Space Charge ◽  
Dipole Model ◽  
Particle Sizes ◽  
Test Results ◽  
Silica Nanocomposites ◽  
Induced Dipole ◽  
Interface Characteristics ◽  
Space Charge Distribution ◽  
Charge Property

This paper prepares polyethylene/silica nanocomposites with concentrations of 3 wt% and 5 wt% by using silicon dioxide (SiO2) nanopowder (nanosilica) with particle sizes of 15 and 50 nm. Samples whose elongations are 3%, 6%, and 10% are prepared. Pulsed electroacoustic technique is applied to evaluate the space charge distribution in samples. Test results show that homocharge near electrodes is generated in the polyethylene/silica nanocomposites. Nanocomposites with a nanoparticle concentration of 3 wt% and particle size of 15 nm suppress the accumulation of space charge effectively. The amount of space charge in the samples increases with the increase in elongation. At an elongation of 10%, packet-like space charge is generated in polyethylene/silica nanocomposites with the concentration of 5 wt% and particle sizes of 15 and 50 nm. The packet-like space charge in nanocomposites whose particle size is 50 nm is more obvious than that in nanocomposites whose particle size is 15 nm. The experiment results are explained by applying interface characteristics, dipole model, and induced dipole model.

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