scholarly journals Preparation and characterization of branched micro/nano Se

2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Yongjun Wu
Keyword(s):  
Reaction Time ◽  
Hydrothermal Method ◽  
Soft Template ◽  
Potent Effect ◽  
Crystallinity Degree ◽  
Factors Influencing ◽  
Optimal Reaction Condition ◽  
External Causes ◽  
Optimal Reaction

Branched micro/nano Se was prepared by the redaction of L-Cys•HCl and H2SeO3 in hydrothermal method, as β-CD was used as soft template. The structures of products were characterized by SEM, TEM and XRD. Some important factors influencing the morphology of products were studied and discussed, including the amounts of soft template, the reaction temperature and the reaction time. The results showed that external causes had a potent effect on the morphology of micro/nano Se. The uniform branched micro/nano Se prepared under the optimal reaction condition was rhombohedral trigonal selenium t-Se0, but its crystallinity degree was low.

Two-Step Preparation of Bio-Diesel from the Used Bleaching Clay

2012 ◽  
Vol 209-211 ◽  
pp. 1774-1777
Author(s):  
Su Xi Wu ◽  
Shuai Hang Yan ◽  
Hui Cai
Keyword(s):  
Reaction Time ◽  
Maximum Yield ◽  
Acid Value ◽  
Raw Material ◽  
Bleaching Clay ◽  
Molar Ratio ◽  
Alkaline Catalyst ◽  
Orthogonal Experiments ◽  
Optimal Reaction Condition ◽  
Optimal Reaction

with the shortage of the raw material oil for producing bio-diesel in China, the oil, recovered from the used bleaching clay which often be discarded by vegetable oil factory, was used to prepare bio-diesel in this trial. Two-step catalyzed process was adopted to produce biodiesel from the oil. The effect of methanol-to-oil molar ratio, alkaline catalyst quantity, reaction temperature and reaction time on the preesterification and transesterification reaction was investigated through orthogonal experiments. Thus the optimal reaction condition came out. Firstly, the optimal pre-esterification condition, under which the end acid value of the product was minimum (i.e. 1.88 mgKOH/g),was to react for 40 h at 60°C,with a methanol-to-oil molar ratio of 12:1, and by adding alkali catalyst 4% based on the oil weight. Secondly，the optimal transesterification condition, under which the maximum yield of bio-diesel can reach up to 98.2%, was to react for 2.5 h at 60°C,with the methanol-to-oil molar ratio of 7:1, and by adding catalyst 1.25% based on the oil weight.

scholarly journals Synthesis of ZnMn2O4 nanostructure via hydrothermal method

2020 ◽  
Vol 9 (3) ◽  
pp. 58-62
Author(s):  
Linh Nguyen Le My ◽  
Nguyen Do Mai
Keyword(s):  
Hydrothermal Method ◽  
Calcination Temperature ◽  
Crystalline Form ◽  
Hydrothermal Time ◽  
X Ray Diffraction ◽  
Spinel Type ◽  
Hydrothermal Temperature ◽  
X Ray ◽  
Factors Influencing

In this study, the spinel-type ZnMn2O4 material was successfully synthesized via hydrothermal method. Several factors influencing the synthesis of material such as Zn/Mn mole ratio, hydrothermal temperature and calcination temperature were studied. The characterization of expected samples using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR), surface area analysis (BET) was conducted. The XRD results indicated that the highly ordered crystalline form of spinel ZnMn2O4 was synthesized in the conditions: Zn/Mn mole ratio of 1:2, hydrothermal temperature of 120 °C, hydrothermal time of 24 h and calcination temperature of 500 °C.

Preparation and Characterization of Zn1-xNixFe2O4 Nanoparticles with Spinel Structure Synthesized by Hydrothermal Method

2018 ◽  
Vol 14 (6) ◽  
pp. 474-480 ◽  
Author(s):  
Xueliang Zhu ◽  
Zhiqiang Wei ◽  
Wenhua Zhao ◽  
Xu-dong Zhang ◽  
Xiao-juan Wu ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Spinel Structure

Correlative experimental and theoretical characterization of transition metal doped hydroxyapatite nanoparticles fabricated by hydrothermal method

2021 ◽  
Vol 173 ◽  
pp. 110911
Author(s):  
Anastasia V. Sadetskaya ◽  
Natalia P. Bobrysheva ◽  
Mikhail G. Osmolowsky ◽  
Olga M. Osmolovskaya ◽  
Mikhail A. Voznesenskiy
Keyword(s):  
Transition Metal ◽  
Hydrothermal Method ◽  
Hydroxyapatite Nanoparticles ◽  
Theoretical Characterization ◽  
Metal Doped

scholarly journals Analysis of work-related accidents and ill-health in Brazil since the introduction of the accident prevention factor

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Helena Eri Shimizu ◽  
Josierton Cruz Bezerra ◽  
Luciano José Arantes ◽  
Edgar Merchán-Hamann ◽  
Walter Ramalho
Keyword(s):  
Health Status ◽  
Occupational Health ◽  
Health Services ◽  
Economic Activity ◽  
Accident Prevention ◽  
Multiplication Factor ◽  
Work Related ◽  
Factors Influencing ◽  
Before And After ◽  
External Causes

Abstract Background Since 2004, Brazil has had a national policy for occupational health and safety. This policy means companies’ tax burden is altered according to the numbers of work-related accidents and ill-health amongst their workers. In 2010, a multiplication factor was introduced to this policy, called the Accident Prevention Factor. The idea of this new multiplication factor is to encourage individual employers to take initiatives to prevent accidents and ill health in the workplace. This study was designed to investigate the incidence of work-related accidents and ill-health in Brazil according to their causes, their severity, and the economic activity in which they occur, and to compare the data before and after the introduction of the Accident Prevention Factor. Methods An ecological study was conducted by analyzing the time series of work-related accidents/ill-health between 2008 and 2014 from the Brazilian social security system (Previdência Social) statistical yearbooks. Incidences were calculated per cause, economic activity, and severity of the accident/ill-health. Data from before and after the introduction of the Accident Prevention Factor were compared using the Mann-Whitney test per cause and per economic activity. Statistical analyses were made using the SPSS software, with significance set at 5%. Results A reduction in the incidence of work-related accidents/ill-health was found across all the groups of causes analyzed, except for the groups “external causes of morbidity and mortality” and “factors influencing health status and contact with health services.” Greater reductions were found for diseases of the musculoskeletal system and connective tissue and diseases of the nervous system. Reductions in work-related accidents/ill-health were found in the different economic activities and in the different severity groups. The highest reduction after the introduction of the Accident Prevention Factor was in manufacturing and production (p < 0.05). Conclusions Overall, the incidence of accidents/ill-health was found to be on decline, except those with external causes of morbidity and mortality and those involving factors influencing health status and contact with health services. The biggest reduction was found in manufacturing and production. However, generally speaking progress still needs to be made in accident prevention and occupational health across a whole range of work environments.

Direct Synthesis of 3,5-Dinitropyrazole Catalyzed by Newly Sulfated Nanosolid Superacid TiO2/ SO

2011 ◽  
Vol 391-392 ◽  
pp. 1296-1301
Author(s):  
Li Min Xi ◽  
Xin Xin Zhang
Keyword(s):  
Direct Synthesis ◽  
Sol Gel ◽  
Acid Base ◽  
Direct Transformation ◽  
Acid Base Titration ◽  
Optimal Reaction Condition ◽  
Superacid Catalyst ◽  
Average Size ◽  
Optimal Reaction ◽  
Xrd And Tem

The newly sulfated nanosolid superacid TiO2/SO4 prepared by sol-gel method was broadly characterized by acid base titration, XRD and TEM, which identified that the superfine solid TiO2/SO4 showing good dispersibility with average size of 27 nm belongs to kind of crystalline nanoparticles. With the help of the catalyst TiO2/SO4, the optimal reaction condition for direct transformation of pyrazole and nitrosonitric acid into 3, 5-Dinitropyrazole was n (pyrazol)=0.10 mol, m (TiO2/SO4 )＝1.5g, V(n-octannol)＝90mL, and V(nitrosonitric acid)＝50mL. Moreover, the optimal yield of the catalytic reaction reached up to 59.4% when the reaction time is 7 hours. The nanosolid superacid catalyst is still of high activity after regenerating eight times by calcination at 600。C.

scholarly journals Synthesis of propylene carbonate from urea and 1,2-propylene glycol over metal carbonates

2011 ◽  
Vol 17 (3) ◽  
pp. 323-331 ◽  
Author(s):  
Jiancheng Zhou ◽  
Wu Dongfang ◽  
Birong Zhang ◽  
Yali Guo
Keyword(s):  
Reaction Time ◽  
Propylene Glycol ◽  
Propylene Carbonate ◽  
Reaction Temperature ◽  
Reaction Conditions ◽  
Lead Carbonate ◽  
Synthetic Process ◽  
Metal Carbonates ◽  
Optimal Reaction ◽  
Mixed Carbonate

A series of single-metal carbonates and Pb-Zn mixed-metal carbonates were prepared as catalysts for alcoholysis of urea with 1,2-propylene glycol (PG) for the synthesis of propylene carbonate (PC). The mixed carbonates all show much better catalytic activities than the single carbonates, arising from a strong synergistic effect between the two crystalline phases, hydrozincite and lead carbonate. The mixed carbonate with Pb/Zn=1:2 gives the highest yield of PC, followed by the mixed carbonate with Pb/Zn=1:3. Furthermore, Taguchi method was used to optimize the synthetic process for improving the yield of PC. It is shown that the reaction temperature is the most significant factor affecting the yield of PC, followed by the reaction time, and that the optimal reaction conditions are the reaction time at 5 hours, the reaction temperature at 180 oC and the catalyst amount at 1.8 wt%, resulting in the highest PC yield of 96.3%.

Characterization of blue CoAl2O4 nano-pigment synthesized by ultrasonic hydrothermal method

2012 ◽  
Vol 38 (7) ◽  
pp. 5707-5712 ◽  
Author(s):  
Jin-Ho Kim ◽  
Bo-Ram Son ◽  
Dae-Ho Yoon ◽  
Kwang-Taek Hwang ◽  
Hyung-Goo Noh ◽  
...  
Keyword(s):  
Hydrothermal Method
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