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Wyszukujesz frazę "Synthesis yield" wg kryterium: Temat


Wyświetlanie 1-4 z 4
Tytuł:
Effects Of Process Parameters On Cu Powder Synthesis Yield And Particle Size In A Wet-Chemical Process
Wpływ parametrów procesu na wydajność syntezy proszku Cu i wielkości cząstek w procesie mokrym chemicznym
Autorzy:
Shin, Y. M.
Lee, J. H.
Powiązania:
https://bibliotekanauki.pl/articles/354168.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wet-chemical process
micron-size Cu powder
Synthesis yield
particle size
gibbs free energy difference
proszek Cu
proces chemiczny mokry
wydajność syntezy
rozmiar cząsteczki
różnica energii swobodnej Gibbsa
Opis:
This study presents a simple wet-chemical process to prepare several micron-size Cu powders. Moreover, changes in powder synthesis yield and particle size are examined with different solvents, synthesis temperatures, and amounts of reducing agent during the synthesis. As a reducing agent and capping agent, L-ascorbic acid and polyvinyl pyrrolidone were used, respectively. The yields in distilled water or an ethylene glycol (EG)/distilled water mixture were higher than that in EG alone, and the yield increased with increasing temperature owing to a lower Δ Gred value. Increasing the L-ascorbic acid concentration also increased the yield. The Cu powder synthesized in 3 h at 90°C in distilled water with 272.8 mM of L-ascorbic acid showed the lowest average particle size of 2.52 μm, indicating mechanisms of short burst nucleation and reduced growth via the increased reduction rate of Cu ions. It is estimated that the nucleation step was nearly completed within 10 min in this system. The Cu powders synthesized in an ethylene glycol/distilled water mixture presented an average particle size of 3.76 μm and the highest yield of 87.9%.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1247-1250
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of the Synthesis Parameters and Analysis of the Impact Sensitivity for Tetrazene Explosive
Autorzy:
Li, Jin-Shuh
Chang, Chun-Chieh
Lu, Kai-Tai
Powiązania:
https://bibliotekanauki.pl/articles/358591.pdf
Data publikacji:
2020
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
tetrazene
yield
optimal synthesis parameters
Taguchi design method
Opis:
Tetrazene [1-(5-tetrazolyl)-4-guanyltetrazene hydrate] is widely used in ordnance systems as a sensitizer of primer compositions, for use in both percussion and stab applications. It can be synthesized by reacting aminoguanidinium bicarbonate (AGB) with sodium nitrite (NaNO2) in the presence of acetic acid. However, little is known about its optimal synthesis parameters in the manufacturing process. In this study, Taguchi's experimental design method was used to further improve the yield of tetrazene. Under the condition that the molar ratio of AGB to NaNO2 was fixed at 1.0:1.2, a L9(33) orthogonal array with three control factors and three levels for each control factor was used to design nine experimental conditions. The experimental data were transformed into a signal-to-noise (S/N) ratio to analyze and evaluate the experimental conditions of the optimal parameter combination for the maximum yield of tetrazene. Verification of the results indicated that the optimal synthesis parameters were as follows: pH value of AGB solution was 5.0, reaction temperature was 35 °C and reaction time was 6 h; the maximum yield of tetrazene could reach 83.7%. Furthermore, the synthesized tetrazene was identified and characterized by elemental analysis (EA), nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR), optical microscopy (OM),particle size distribution analysis (PSDA), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), and its impact sensitivity was determined using a BAM Fallhammer apparatus and the Bruceton analysis method.
Źródło:
Central European Journal of Energetic Materials; 2020, 17, 1; 5-19
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microwave-aided reactions of aniline derivatives with formic acid : inquiry-based learning experiments
Autorzy:
Mycak, Michael
Doležal, Rafael
Bílek, Martin
Kolář, Karel
Powiązania:
https://bibliotekanauki.pl/articles/2175230.pdf
Data publikacji:
2022
Wydawca:
Towarzystwo Chemii i Inżynierii Ekologicznej
Tematy:
inquiry-based learning
amide synthesis
microwave synthesis
amine structure
amide yield
nauka oparta na zapytaniu
synteza amidów
synteza mikrofalowa
struktura amin
Opis:
The synthesis of amides belongs to traditional experimental tasks not only in organic chemistry exercises at universities but also at chemically focused secondary schools or in special practices at general high schools. An example of such a synthesis may be the preparation of acetanilide via reaction of aniline with acetic acid or acetic anhydride. However, both of these reactions are associated with a rather long reaction time and certain hazards that limit their straightforward use in pedagogical practice. Conveniently, the reaction of aniline with acetic acid may be significantly optimised if it is performed under solvent-free conditions in the presence of microwaves, which reduces considerably the reaction time and provides very good yield, compared to traditional heating by a heating nest. In this study, the main pedagogical aim of the experimental design is elucidation of the influence of the structure of the amines on the course of the reaction with formic acid through inquiry-based learning. Specifically, the proposed experiments consist in investigation of the chemical yield achieved in microwave assisted reactions of aniline and its derivatives with formic acid in such a way that is adequate for constructive learning of undergraduate chemistry students. The selected series of amines involves aniline, 4-methoxyaniline, 4-chloroaniline, and 4-nitroaniline. In accordance with the chemical reactivity principles, students gradually realise that the influence of the substituent is reflected in the reaction yield, which grows in the following order: N-(4-nitrophenyl)formamide ˂ N-(4-chlorophenyl)formamide ˂ N-phenylformamide ˂ N-(4-methoxyphenyl)formamide. Therefore, the results of the experiments enable students to discover that stronger basicity of the amine increases the yield of the amide. In order to deepen the students’ chemical knowledge and skills, the concept of the experiments was transformed to support inquiry-based student learning. The proposed experiments are intended for experimental learning in universities educating future chemistry teachers, but they may be also utilised in the form of workshops for students at secondary schools of a general educational nature.
Źródło:
Chemistry-Didactics-Ecology-Metrology; 2022, 27, 1-2; 135--151
2084-4506
Pojawia się w:
Chemistry-Didactics-Ecology-Metrology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Overexpression of stress-related genes in Cuscuta campestris in response to host defense reactions
Autorzy:
Rezaei, H.
Alamisaeed, K.
Moslemkhani, C.
Powiązania:
https://bibliotekanauki.pl/articles/81031.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Cuscuta campestris
parasitic plant
crop yield
haustorium
RNA extraction
cDNA synthesis
real-time reverse transcription polymerase chain reaction
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2017, 98, 2
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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