scholarly journals A study of the structure and morphology of the graphite electrochemical exfoliation products

2021 ◽  
Vol 6 (4) ◽  
pp. 267-278
Author(s):  
Yulian A. Khan ◽  
Tatyana P. Dyachkova ◽  
Evgeny S. Bakunin ◽  
Elena Yu. Obraztsova ◽  
Artyom V. Rukhov ◽  
...  

The paper presents a generalized analysis of the results of scanning electron microscopy, energy dispersive spectroscopy, and TG/DSC analysis of electrochemical exfoliation products from two types of initial graphite raw materials at different process temperatures in solutions of potassium hydroxide (KOH) and sulfuric acid (H2SO4). It is shown that an increase in the concentration of an alkaline electrolyte in the range from 0.1 to 1.0 molL–1 promotes the intensification of the process of separation and splitting of graphite into fragments. In the case of the formation of large fragments, the product contains a significant amount of intercalated potassium ions, which are not removed when the material is washed off. The products of electrochemical exfoliation of the spent electrocontact graphite material demonstrate structural heterogeneity, contain a significant amount of functional groups and impurities of the amorphous phase. Thermogravimetric curves have several sections of sample weight reduction. After heating these materials in an inert atmosphere to 900 °C, the total weight loss reaches 66 %. From a thermally expanded graphite foil, samples of nanographites, extremely homogeneous in chemical composition, with increased thermal stability and a minimum number of surface defects were obtained. The total weight loss of the samples when heated in an inert atmosphere to 900 °C does not exceed 17 %. It was shown that the replacement of an alkaline electrolyte with a sulfuric acid solution leads to an increase in the number of defects in the product.

2020 ◽  
Vol 17 (3) ◽  
pp. 499-504
Author(s):  
Le Nguyen Tu Linh ◽  
Vu Quang Dao ◽  
Bui Dinh Thach ◽  
Trinh Thi Ben ◽  
Tran Thi Linh Giang ◽  
...  

Nowadays, herbs have become a popular form of healthcare. Clinacanthus nutans (Burm.f.) Lindau (family Acanthaceae) is popular in Asia, especially in the tropical countries. Extracts of C. nutans leaves are widely used to treat diseases of skin, anti-inflammatory, anti-virus, anticancer, antioxidant, antidiabetic, immunomodulatory, wound healing and analgesic activities, etc. This study determined the parameters of ethanol extract of C. nutans leaves including pH, total weight loss due to water, total ash content, heavy metal content, microbiological limits, pesticide residual content, presence and contents of C-flavones. The C-flavones such as shaftoside, orientin, isovitexin and vitexin have been found to be major flavonoids in the leaves of this plant. Therefore, we had used a two-step method using thin layer chromatography (TLC) and high pressure liquid chromatography (HPLC) for the rapid identification and quantification of the flavones C-glycosides in ethanol extract C. nutans leaves. These results provided useful information for the evaluation of quality of C. nutans raw materials and its commercial products. Moreover, that contributed to the establishment of extract standard from the leaves of C. nutans. The parameters of the ethanol extract of C. nutans leaves were obtained as follows: pH (5,23 ± 0,35), total weight loss due to water (15,62 ± 0,25%), total ash (13,85 ± 0,98%), microbiological limits are achieved the requirement of medicinal standards, content heavy metal and residue of pesticide are not detected. Contents of C-flavones: shaftoside (0,69 ± 0,04 mg/g), orientin (0,24 ± 0,008 mg/g), isovitexin (0,015 ± 0,003 mg/g), vitexin were very low or undetectable.


2020 ◽  
Vol 16 (12) ◽  
pp. 1978-1987
Author(s):  
Masahiro Ohira ◽  
Yasuhiro Watanabe ◽  
Takashi Yamaguchi ◽  
Atsuhito Saiki ◽  
Takashi Oshiro ◽  
...  

2021 ◽  
Vol 12 (1) ◽  
pp. 43-47
Author(s):  
Archana Sahu ◽  
Mridu Sanjana Kujur ◽  
Lalchand Sahu ◽  
Rakesh Singh Thakur ◽  
Saroj Parhate

Rasa Shastra is a branch of Ayurveda, which deals with the uses of drugs originated mainly from metals and minerals substances like Tamra Bhasma. Raw Tamra may contain impurities, heterogeneous and unwanted qualities. Aim of Shodhana is to make it purified and make it free from toxicity and suitable for the body. In this study Shodhana of Tamra was performed by classical method mentioned in Rasa Ratna Samucchya. In this process for Samanya Shodhana of Tamra. It was heated and after red hot it was quenched for 7 times in Tila Taila, Takra, Gomutra, Kanji and Kulattha kwatha in order. Total weight loss of Tamra after Samanya Shodhana was 13.33%, which shows removal of impurities. Literally, Shodhana is a procedure of elimination of Doshas in a drug. After Shodhana Loss on weight of Tamra, pH and colour changes of all liquid media were observed.


Author(s):  
Ali A. Rostami ◽  
Susan E. Wrenn ◽  
Mohammad R. Hajaligol

The heating of fuel particles is generally the first step in the process of gasification or combustion of solid fuels such as coal and biomass. The particle heating that is achieved via combined convection and radiation effects requires a rigorous analysis of heat transfer within as well as outside of the particle, which makes the lumped capacity approximation unsuitable. A more adequate representation of the heating-up process requires the inclusion of the internal convection within the solid particle, the blowing effects on the particle surface, the spatial and temporal variations of the solid thermal conductivity as well as the heat of pyrolysis reactions. The internal convection tends to equalize the temperature distribution within the solid, while the blowing effect contributes to the boundary layer thickening and eventually to a reduction in the convection heat transfer to the particle. To include the above-mentioned effects, a kinetic model for the total weight loss of the solid material was coupled with the heating model. A simple first-order reaction model for the total weight loss was utilized in this study. For materials with high moisture contents, the heat of pyrolysis reactions is an important factor in the heating rate and non-uniform heating of the solid particle. Thermal equilibrium between the solid and evolved gases was assumed within the particle and the equations for the conservation of mass and energy were solved numerically. Results show that surface blowing which is due to the devolatilization of the particle tends to reduce the convection heat transfer from the hot gases to the particle. Internal convection contributes to thermal uniformity in the particle. Heat of pyrolysis reactions plays an important role in the heating profile of the particle. It delays the temperature rise of the particle until most of the volatile materials is released.


2006 ◽  
Vol 106 (8) ◽  
pp. A39
Author(s):  
A.L. Greenwald ◽  
M. Richards ◽  
M.M. Wrobleski ◽  
C.C. Roberts ◽  
C.R. Koch

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Yingying Luo ◽  
Abdel Wahab Jalal Eldin ◽  
Raad Haddad ◽  
Nahid Keshavarzi ◽  
Shokoufeh Khalatbari ◽  
...  

Abstract Background Obesity and diabetes as well as their related complications result in both individual and global health burdens. Among patients who present with both obesity and diabetes, bariatric surgery can lead to remission of both these diseases. However, the possible impact of diabetes on the magnitude of weight loss outcomes after bariatric surgery has not been quantified. Methods To address this question, we extracted data from Michigan Bariatric Surgery Cohort (MI-BASiC) to see whether diabetes at baseline could be a predictor of weight loss outcomes. Consecutive patients 18 years of age or older undergoing gastric bypass (GB) or sleeve gastrectomy (SG) for obesity at the University of Michigan between January 2008 and November 2013 were included in our retrospective cohort. All patients had either body mass index (BMI) > 40 kg/m2 or BMI 35 – 39.9 kg/m2 with comorbid condition. Firstly, we performed Generalized Linear Mixed Model (GLMM) analysis to compare the probability of achieving BMI under 30kg/m2 or achieving excess body weight loss (EBWL) 50% or more for patients with or without diabetes. We then further tested the effect of presence of diabetes for the BMI outcomes across time using Linear Mixed Model (LMM) analysis. Finally, we conducted a LMM analysis to determine if diabetes is a predictor of the future weight loss, percentage of total weight loss or percentage of excess weight loss over 5 years of follow up. Results Based on our criteria, 380 patients were included for GB [female 305 (80.3%), mean age 43.6±0.6 years, mean BMI 47.3±0.4kg/m2, diabetes 149 (39.2%), on insulin 45 (11.8%)] and 334 for SG [female 259 (77.5%), mean age 45.3±0.6 years, mean BMI 49.9±0.5kg/m2, diabetes 108 (32.3%), on insulin 29(8.7%)]. From GLMM analysis, the presence of diabetes at baseline did not impact the probability of achieving BMI under 30kg/m2 (p=0.0848), but substantially impacted the probability of achieving 50% or more EBWL (p=0.0021) with individuals without diabetes having a 1.6 (odds ratio 1.56, 95% CL [1.18-2.08]) times higher chance to achieve this threshold. We also showed that individuals with diabetes at baseline had a significant effect to modify BMI points lost, regardless of the surgery type (p=0.0178). The presence of diabetes at baseline diminished weight loss by 1.2 BMI points (95% CL [0.21- 2.20]) which is roughly 10 to 15% of the total BMI points to be lost. LMM analysis further confirmed that after adjusting the time, surgery type, age, gender and baseline weight, there was still a significant difference of absolute weight loss (p=0.0110), percentage of total weight loss (p=0.0089) and percentage of excess weight loss (p=0.0365) between individuals with diabetes versus individuals without diabetes. Conclusion In conclusion, our data demonstrate that diabetes diminishes the ultimate weight loss effect of bariatric surgery. Further research is needed to understand why this is the case.


2014 ◽  
Vol 6 ◽  
pp. IJIS.S13338 ◽  
Author(s):  
Addis T. Kebede ◽  
Suresh K. Raina ◽  
Jacques M. Kabaru

Silk cocoon nests, as well as the fiber structure, compositions, and properties of the African wild silkmoth, Anaphe panda, collected from Kakamega tropical rainforest (western Kenya) were studied using scanning electron microscopy, high-pressureliquid chromatography, tensile tests, and thermogravmetric analysis, and they were compared with the industrial standard, Bombyx mori. Cocoon nests are complex structures made up of inner, middle, and outer layers. The inner hard parchment was found to protect a mass of (20–200) individual soft flossy cocoons that enclose the pupae. The outer surface of the cocoon nests was covered with a mass of hair-like bristles. Fibers contained crescent-shaped and globular cross-sections with nods at regular intervals. Alanine (34%) and glycine (28%) were the dominant fibroin amino acids observed. Total weight loss after degumming the cocoon nest was 25.6%. Degummed fibers showed higher moisture regain of 9% when compared with cocoon nests (8%). The fibers had 0.4 GPa breaking stress and 15.4% breaking strain. Total weight loss values after thermogravimetric analysis were 86% and 90% for degummed fibers and cocoon shells, respectively.


2020 ◽  
Vol 16 (11) ◽  
pp. 1850-1856 ◽  
Author(s):  
Beata M.M. Reiber ◽  
Mark Tenhagen ◽  
Rosalie Barendregt ◽  
Mauk P. Mekel ◽  
Huib A. Cense ◽  
...  

1997 ◽  
Vol 24 (1) ◽  
pp. 62-66 ◽  
Author(s):  
T. B. Whitaker

Abstract Raw shelled peanut lots produced in the United States are inspected for aflatoxin using a sampling plan designed by the Peanut Administrative Committee (PAC). The aflatoxin concentration of most peanut lots rejected by the PAC sampling plan is reduced by using a blanching process that removes the testa or seed coat from the seed and then removing damaged or discolored seeds from the lot using electronic color sorters. Comparing aflatoxin sample results on lots before and after the blanching process indicates that the two-step process is effective for reducing aflatoxin in contaminated lots. The average aflatoxin reduction among the 8911 lots blanched and color sorted over 5 crop yr (1990 to 1994) was 89.9%. The blanching process was equally efficient in reducing aflatoxin for all peanut market types and grades represented in the data base. The average total weight loss among all 8911 lots blanched over the 5 crop yr was 16.8%. Both the percentage aflatoxin reduction and the percentage total weight loss that resulted from blanching was related to the amount of aflatoxin in unblanched lots. As the aflatoxin concentration among unblanched lots decreased, the percentage aflatoxin reduction and the percentage total weight loss associated with the blanching process both decreased.


2016 ◽  
Vol 26 (8) ◽  
pp. 1794-1798 ◽  
Author(s):  
Ricard Corcelles ◽  
Mena Boules ◽  
Dvir Froylich ◽  
Amani Hag ◽  
Christopher R. Daigle ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document