A Novel Spray Based Method for the Production of Semiconductor Nanocrystals

2005 ◽  
Vol 879 ◽  
Author(s):  
Lilac Amirav ◽  
Efrat Lifshitz
Keyword(s):  
Size Distribution ◽  
Semiconductor Nanocrystals ◽  
Average Diameter ◽  
Solute Concentration ◽  
Degree Of Crystallinity ◽  
Attractive Alternative ◽  
Spray Droplet ◽  
Zinc Blend ◽  
Semiconductor Nanoparticle ◽  
High Degree

AbstractWe present a novel spray based method for the formation and production of semiconductor nanocrystals that provides an attractive alternative to the commonly used epitaxial and colloidal procedures. According to this spray-based method, mainly thermospray, solutions of semiconductor salts are first sprayed into monodispersed droplets, which subsequently become solid nanoparticles by solvent evaporation. A semiconductor nanoparticle is produced from a single spray droplet upon the full vaporization of the solvent. The average diameter and size distribution of the final nanocrystals are controlled and determined by the solute concentration of the sprayed solution and by the droplet size, hence by the spray production parameters. The spray-produced nanocrystals are collected on any selected solid support. Representative results, shown in this paper, reveal the formation of CdS nanocrystals in the size range of 3 to 6 nanometer and with a size distribution of as low as five percents. A further structural analysis of these nanocrystals showed that they were formed in the zinc blend phase with high degree of crystallinity.

scholarly journals Efficient Hydrothermal Synthesis of SSZ-13 with Variable Grain Size

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1829 ◽  
Author(s):  
Yibao Wang ◽  
Chen Wang ◽  
Jun Wang ◽  
Jianqiang Wang ◽  
Lei Wang ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Size Distribution ◽  
Degree Of Crystallinity ◽  
Similar Degree ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
Seed Method ◽  
Industrial Needs ◽  
High Degree

To meet the industrial needs for SSZ-13, variable sizes of SSZ-13 with different Si/Al ratios were firstly obtained by conventional hydrothermal synthesis using the seed method. Using a set of characterizations, like X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM), the physicochemical structure and size distribution could be traced. After the specific Si/Al ratio of SSZ-13 zeolites was optimized, synthesized by changing the amounts of structure-directing agents (SDAs) and NaOH, the obtained SSZ-13 showed a high degree of crystallinity. With the limitation of the pH values, the variation of the alkalinity and water content was not helpful to generate different grain sizes of SSZ-13 materials. With the help of ground seed, the various grain sizes of SSZ-13s from 0.4 to 4 μm had a similar degree of crystallinity and size distribution. Moreover, due to the identical intensity of the Al peak in the NMR results, the different grain sizes of SSZ-13s had the same acidity. Our study revealed that using the seed method was an easy and efficient way to synthesize SSZ-13s with different sizes.

scholarly journals Synthesis and Characterization of Nano-Sized 4-Aminosalicylic Acid–Sulfamethazine Cocrystals

Pharmaceutics ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 277 ◽  
Author(s):  
Ala’ Salem ◽  
Anna Takácsi-Nagy ◽  
Sándor Nagy ◽  
Alexandra Hagymási ◽  
Fruzsina Gősi ◽  
...  
Keyword(s):  
High Power ◽  
Active Pharmaceutical Ingredient ◽  
Polymorphic Form ◽  
Degree Of Crystallinity ◽  
Dissolution Enhancement ◽  
Aminosalicylic Acid ◽  
Nano Technology ◽  
Power Ultrasound ◽  
High Power Ultrasound ◽  
High Degree

Drug–drug cocrystals are formulated to produce combined medication, not just to modulate active pharmaceutical ingredient (API) properties. Nano-crystals adjust the pharmacokinetic properties and enhance the dissolution of APIs. Nano-cocrystals seem to enhance API properties by combining the benefits of both technologies. Despite the promising opportunities of nano-sized cocrystals, the research at the interface of nano-technology and cocrystals has, however, been described to be in its infancy. In this study, high-pressure homogenization (HPH) and high-power ultrasound were used to prepare nano-sized cocrystals of 4-aminosalysilic acid and sulfamethazine in order to establish differences between the two methods in terms of cocrystal size, morphology, polymorphic form, and dissolution rate enhancement. It was found that both methods resulted in the formation of form I cocrystals with a high degree of crystallinity. HPH yielded nano-sized cocrystals, while those prepared by high-power ultrasound were in the micro-size range. Furthermore, HPH produced smaller-size cocrystals with a narrow size distribution when a higher pressure was used. Cocrystals appeared to be needle-like when prepared by HPH compared to those prepared by high-power ultrasound, which had a different morphology. The highest dissolution enhancement was observed in cocrystals prepared by HPH; however, both micro- and nano-sized cocrystals enhanced the dissolution of sulfamethazine.

scholarly journals Nucleation of Ga droplets self-assembly on GaAs(111)A substrates

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Artur Tuktamyshev ◽  
Alexey Fedorov ◽  
Sergio Bietti ◽  
Stefano Vichi ◽  
Riccardo Tambone ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Size Distribution ◽  
Self Assembly ◽  
Cluster Size ◽  
Droplet Size Distribution ◽  
Local Environment ◽  
The Self ◽  
Critical Cluster ◽  
Droplet Nucleation ◽  
High Degree

AbstractWe investigated the nucleation of Ga droplets on singular GaAs(111)A substrates in the view of their use as the seeds for the self-assembled droplet epitaxial quantum dots. A small critical cluster size of 1–2 atoms characterizes the droplet nucleation. Low values of the Hopkins-Skellam index (as low as 0.35) demonstrate a high degree of a spatial order of the droplet ensemble. Around $$350\,^{\circ }\hbox {C}$$ 350 ∘ C the droplet size distribution becomes bimodal. We attribute this observation to the interplay between the local environment and the limitation to the adatom surface diffusion introduced by the Ehrlich–Schwöbel barrier at the terrace edges.

CYTOLOGY OF POPLAR SPECIES AND NATURAL HYBRIDS

1938 ◽  
Vol 16c (11) ◽  
pp. 445-455 ◽  
Author(s):  
F. H. Peto
Keyword(s):  
Size Distribution ◽  
Genetic Factors ◽  
Chromosome Complement ◽  
Pollen Grains ◽  
Pollen Size ◽  
Cell Nuclei ◽  
Good Pollen ◽  
Natural Hybrids ◽  
Pollen Diameter ◽  
High Degree

Complete analyses of pollen-mother-cell nuclei at first metaphase, percentage good pollen, pollen diameter and pollen-size distribution were determired for the following poplar species and natural hybrids: Populus grandidentata Michx., P. tremuloides Michx., P. eugenei Simon Louis, P. alba L., P. canescens Sm., natural hybrids of P. alba × P. grandidentata and of P. alba × P. tremuloides.Both of the P. alba and two of the four P. canescens trees examined were triploids (2n = 57) while all other trees examined were diploids (2n = 38). Meiotic observations on the natural hybrids indicated a high degree of homology between the chromosomes of P. alba and the native aspens (P. grandidentata and P. tremuloides), since 17 to 19 bivalents were usually found at first metaphase. In collections from one triploid P. canescens and two diploid alba-grandidentata hybrid trees, failure of a high proportion of the chromosomes to pair was attributed to genetic factors limiting pairing, rather than to non-homology.Pollen characters such as percentage good pollen, pollen diameter, and pollen size distribution were, in most cases, not indicative of the chromosome number or pairing relations at first metaphase. Consequently, triploids could not be detected by pollen observations under the conditions of this experiment. In spite of the lack of correlation between first metaphase and pollen observations, abnormally large pollen grains were observed in collections from several of the trees, and these were considered to contain the diploid or unreduced chromosome complement. The tendency for the poplars to produce unreduced pollen grains probably accounts for the number of triploid trees discovered in Canada and Sweden.

scholarly journals Morphology, Stability, and Application of Lycopene Microcapsules Produced by Complex Coacervation

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Glaucia A. Rocha-Selmi ◽  
Carmen S. Favaro-Trindade ◽  
Carlos R. F. Grosso
Keyword(s):  
Encapsulation Efficiency ◽  
Gum Arabic ◽  
Average Diameter ◽  
Stability Test ◽  
Free Form ◽  
Complex Coacervation ◽  
The Stability ◽  
Processing And Storage ◽  
High Degree ◽  
And Storage

The interest in lycopene has increased in recent years due to studies that associate it with the reduction in risk of developing cardiovascular diseases and cancer. However, due to its high degree of unsaturation, this carotenoid is inclined to isomerize and oxidize during processing and storage, making it difficult to use in the food industry. Microencapsulation can improve this situation, increasing its stability and making incorporation into food formulations possible. Thus, the aim of this study was to microencapsulate lycopene by complex coacervation using gelatin and gum Arabic as the encapsulating agents. The microcapsules were evaluated based on the encapsulation efficiency and their morphology and then submitted to a stability test and applied in cake making. Most of the systems studied presented spherical microcapsules with defined walls. The encapsulation efficiency values were above 90%, and the average diameter of the capsules ranged from 61 to 144 μm. The stability test showed that microencapsulation offered greater protection to the lycopene as compared to its free form. The application of nonfreeze dried coacervated microcapsules in cake making was satisfactory, but the color transference was low when freezedried coacervated microcapsules were used.

Colloidal synthesis of monodisperse trimetallic IrNiFe nanoparticles as highly active bifunctional electrocatalysts for acidic overall water splitting

2017 ◽  
Vol 5 (47) ◽  
pp. 24836-24841 ◽  
Author(s):  
Luhong Fu ◽  
Gongzhen Cheng ◽  
Wei Luo
Keyword(s):  
Synergistic Effect ◽  
Size Distribution ◽  
Water Splitting ◽  
Average Diameter ◽  
Colloidal Synthesis ◽  
Synthetic Method ◽  
Alloy Nanoparticles ◽  
Narrow Size Distribution ◽  
Acidic Media ◽  
Highly Active

Monodisperse IrNiFe alloy nanoparticles with an average diameter of 2.2 nm have been synthesized by a colloidal synthetic method. By taking advantage of the synergistic effect between Ir, Ni and Fe and the ultrasmall NPs with narrow size distribution, the as-synthesized IrNiFe catalyst exhibits superior HER/OER performances in acidic media.

scholarly journals RESEARCH OF THE EJECTING PROPERTIES OF A POLYFRACTION BULK MATERIAL FLOW

2018 ◽  
Vol 3 (3) ◽  
pp. 46-51
Author(s):  
Евгений Попов ◽  
Evgeniy Popov
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Material Flow ◽  
Bulk Material ◽  
Aerodynamic Resistance ◽  
Average Diameter ◽  
Resistance Coefficient ◽  
Free Falling ◽  
The Given

This work is aimed at confirming the adequacy of the probabilistic and statistical approach to determining the aerodynamic resistance coefficient of particles in a flow of the free falling polyfractional material, suggested by the author. The aerodynamic resistance coefficient of particles in a flow of falling material is defined by calculating the probability of finding particles out of air shadows of the neighboring particles. The laboratory experiment was performed on the offered experimental samples of bulk materials having different particle size distribution, but the identical average diameter of particles. The design of a laboratory experimental installation which allows determining the consumption of air, ejected by a polyfractional material flow, was described. The amount of the air, ejected with experimental samples, depends on their particle size distribution that confirms the insufficiency of describing the properties of bulk material only with the average diameter value. The given comparison of results of the analytical calculations with experimental data shows the reliability and adequacy of the calculated values.

scholarly journals Green Fabrication of Thermal-stable oxidized Cellulose Nanocrystals by Evolutive Fenton Reaction and In-Situ Nanoreinforced Thermoplastic Starch

2021 ◽  
Author(s):  
Bingbing Gao ◽  
Jiahui Yang ◽  
Shuidong Zhang ◽  
Xiangyu Li
Keyword(s):  
Fenton Reaction ◽  
Primary Alcohol ◽  
Average Diameter ◽  
Reactive Extrusion ◽  
Thermoplastic Starch ◽  
Degree Of Crystallinity ◽  
Carboxyl Content ◽  
In Situ Forming ◽  
Interfacial Compatibility

Abstract High performances fiber and improved interfacial interaction can enhance the properties of polymer composites. Herein, microcrystalline cellulose (MCC) was oxidized by H2O2/CuSO4, a new Fenton process, to achieve oxidized MCC (OCNCs) with 16 ± 1% carboxyl content. Noteworthy, the thermal stability of OCNC was superior to CNC prepared by acid hydrolysis. Interestingly, the primary alcohol groups of MCC were selective oxidized and OCNCs achieved 11.0 nm, 231.6 nm and 72% of average diameter, length and degree of crystallinity, respectively. Then glycerol, starch and OCNCs were reactive extruded to fabricate TPS/OCNC bionanocomposites and their structure and performances were evaluated systematically. Strikingly, significant improvement in glass transition temperature (from 63.1 to 94.5 °C) and notch impact strength (from 1.3 to 3.9 kJ/m2) were noted for the amorphous TPS/OCNC with 1 wt% OCNC, and its tensile strength achieved 20.5 MPa, simultaneously. The improved mechanism of these performances was assigned to In-Situ forming “Carboxyl-Hydroxyl” hydrogen bonds which acted as the physically cross-linking interactions and improved the interfacial compatibility. We showcase Fenton reaction and reactive extrusion as the facile strategy to prepare sustainable and biodegradable TPS/OCNC bionanocomposites with properties more suitable for daily applications to replace petroleum-based plastic and eliminated the pollution of “microplastics.”

Synthesis of LiCoO2 particles with tunable sizes by a urea-based-homogeneous-precipitation method

2020 ◽  
Vol 111 (4) ◽  
pp. 347-355
Author(s):  
Munekazu Motoyama ◽  
Hiroki Iwasaki ◽  
Miyuki Sakakura ◽  
Takayuki Yamamoto ◽  
Yasutoshi Iriyama
Keyword(s):  
Size Distribution ◽  
Average Diameter ◽  
Precipitation Method ◽  
Homogeneous Precipitation ◽  
Uniform Size ◽  
Homogeneous Precipitation Method ◽  
Wide Range ◽  
Size Uniformity ◽  
Average Size ◽  
Uniform Size Distribution

Abstract This paper reports the synthesis of monodisperse spherical LiCoO2 particles in a wide range of average diameter using a urea-based-uniform-precipitation method. The average diameter of LiCoO2 particles can be varied from 2 to 14 lm with a uniform size distribution. The effective approach to maintain the size uniformity while changing the average size of LiCoO2 particles is to keep the ratio of [CO(NH2)2] to [CoSO4] at 8 even when the CoSO4 and urea concentrations are changed.

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