Reference Samples
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2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Anna Rudawska

AbstractThe aim of the article was to determine the compressive strength and compressive strain of an unmodified and a modified epoxy compounds containing a montmorillonite filler, as well as to determine the effect of temperature and an aging time on the mechanical parameters of the considered epoxy compounds. The subject of the research was both the unmodified and the modified adhesive compounds. The unmodified epoxy compounds were made in four variants, which included the epoxy resins based on a bisphenol A as well as the curing agents: a triethylenetetramine and a polyamide curing agent. The modified compounds containing the montmorillonite filler, were also made in four variants. The samples were subjected in a thermal chamber at 80 °C for 1 and 2 months and in a thermal shock chamber in the temperature range from − 40 °C to 80 °C for 1 and 2 months. The reference samples were seasoned at room temperature 20–25 °C. The epoxy compounds samples were subjected to the compression strength tests in accordance with ISO 604 standard. The compressive strength is influenced by the environment and temperature, the aging time and the presence of the modifying agent. The epoxy compounds subjected at elevated or variable temperatures have higher compressive strength than the reference epoxy compounds. The operation of the climatic chamber or the thermal shock chamber makes the samples more deformable than the reference samples.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kristina Čabanová ◽  
Oldřich Motyka ◽  
Hana Bielniková ◽  
Lenka Čábalová ◽  
Petr Handlos ◽  
...  

AbstractSolid particles, predominantly in micron and submicron sizes, have repeatedly been observed as a threat to a human health unique compared to the other textures of the same materials. In this work, the hypothesis the solid metal-based particles play a role in the pathogenesis of chronic hypertrophic rhinitis was investigated in patients who had not responded positively to medication. In the group of 40 randomly selected patients indicated for surgical mucotomy, the presence of solid micro- and submicron particles present in their nasal mucosa was assessed. For comparison, a set of 13 reference samples from patients without diagnosed chronic hypertrophic rhinitis was evaluated. The analysis was performed using Raman microspectroscopy. The advantage of this method is the direct identification of compounds. The main detected compounds in the mucosa samples of patients with chronic hypertrophic rhinitis were TiO2, carbon-based compounds, CaCO3, Ca(Fe, Mg, Mn)(CO3)2 MgCO3, Fe2O3, BaSO4, FeCO3 and compounds of Al and Si, all of which may pose a health risk to a living organism. In the reference samples, only TiO2 and amorphous carbon were found. In the control group mucosa, a significantly lower presence of most of the assessed compounds was found despite the longer time they had to accumulate them due to their higher mean age. Identification and characterisation of such chemicals compounds in a living organism could contribute to the overall picture of the health of the individual and lead to a better understanding of the possible causes not only in the chronic hypertrophic rhinitis, but also in other mucosal and idiopathic diseases.


Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1505
Author(s):  
Sergey Kustov ◽  
Andrey Saren ◽  
Bruno D’Agosto ◽  
Konstantin Sapozhnikov ◽  
Vladimir Nikolaev ◽  
...  

In this work we create in 10 M Ni-Mn-Ga martensitic samples special martensitic variant structures consisting of only three twins separated by two a/c twin boundaries: Type I and Type II, with relatively low and very high mobility, respectively. The “domain engineered” structure thus created allows us to investigate the dynamics of a single highly mobile a/c twin boundary (TB). We show that temperature variations between 290 and 173 K in our samples induce an intense transitory internal friction at ultrasonic frequencies ca. 100 kHz, peaking around 215 K. A comparison is made of the data for the “domain engineered” sample with the behaviour of reference samples without a/c TB. Reference samples have two different orientations of a/b twins providing zero and maximum shear stresses in a/b twinning planes. We argue, first, that the transitory internal friction, registered at rather high ultrasonic frequencies, has magnetic origin. It is related with the rearrangement of magnetic domain structure due to the motion of a/c twin boundary induced by thermal stresses. This internal friction term can be coined “magnetic transitory internal friction”. Magnetic transitory internal friction is a new category, linking the classes of transitory and magnetomechanical internal friction. Second, the structure of a/b twins is strongly non-equilibrium over a broad temperature range. As a consequence, the Young’s modulus values of the samples with maximum shear stress in a/b twinning planes can take any value between ca. 15 and 35 GPa, depending on the prehistory of the sample.


2021 ◽  
Vol 11 (18) ◽  
pp. 8777
Author(s):  
Ngoc Nguyen Vo ◽  
Huu Tam Tran ◽  
Quan Thuy Truong ◽  
Thuy Huong Nguyen

Hematological reference samples for external quality assessment (EQA) in hematology are essential for many laboratories in Vietnam, however, the prices are high along with short storing time. This study attempted to establish an optimal formula for the manufacture of hematological reference samples for hematological EQA programs. Human red blood cells (RBCs) were mixed with goose RBCs (pseudo-leucocytes) and goat RBCs (pseudo-platelets) as alternatives for white blood cells (WBCs) and platelets (PLTs), respectively, in different formulas of storage media. The optimal formula was obtained using response surface methodology–central composite design (RSM-CCD). Three main factors affecting the concentrations of RBCs were determined by Plackett–Burmann matrix. The optimal concentrations determined by RSM-CCD were 46% serum, 0.44 g/L neomycin sulfate, and 2.5% glycerol. The model predicted that the maximum number of human RBCs was 4.1 × 1012 cells/L, pseudo-leucocytes was 6.4 × 109 cells/L, and pseudo-platelets was 188 × 109 cells/L. The practical concentrations of RBCs, pseudo-leucocytes, and pseudo-platelets were 4.21 × 1012 cells/L, 6.4 × 109 cells/L, and 187 × 109 cells/L, respectively, which showed 98.93% similarity with theoretical data. This result could be a premise for further study to improve manufacturing of hematological reference samples for hematology EQA programs.


2021 ◽  
Vol 1 (3) ◽  
pp. 87-90
Author(s):  
Muhammad Usman Iqbal ◽  
Muhammad Ahsan Butt ◽  
Nasir Siddique ◽  
Qazi Laeeque Ahmad ◽  
Sajjad Ahmad ◽  
...  

2021 ◽  
Vol 39 (9) ◽  
pp. 1151-1160
Author(s):  
Li Tai Fang ◽  
Bin Zhu ◽  
Yongmei Zhao ◽  
Wanqiu Chen ◽  
Zhaowei Yang ◽  
...  

2021 ◽  
Author(s):  
Sachiko Kakimoto ◽  
Masato Yoshimitsu ◽  
Kyohei Kiyota

Abstract Methylmercury (MeHg) pollution is currently widespread in paddy soil and sediment, posing a health hazard risk during the harvesting of rice grains. However, to date, a simple and universal method for quantifying MeHg in the soil is unavailable. Therefore, we aimed to develop a solid-phase extraction-based method using gas chromatography mass spectrometry (GC-MS). In this study, MeHg was purified from the soil matrix using optimized solid-phase extraction; our method reduced the use of organic solvents and did not require harmful reagents such as alkaline solution and toluene. The limit of quantification in the sample was determined to be 7.5 ng/g. The MeHg recovery in reference samples was 96.2–102.6%, and intra- and inter-assay coefficients of variation were 3.4–7.1% and 4.3–7.1%, respectively, indicating high validation performance. Furthermore, the MeHg levels of the five tested reference samples were determined to be 64.1 ng/g or not detected, and these levels were well below the Japanese regulatory criteria. This new method could provide reliable and useful data for environmentalists and agriculturalists to prevent MeHg pollution, facilitating the improvement of food safety for harvests from paddy soil.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jianrong Jiang ◽  
Guoquan Lu ◽  
Qing Wang ◽  
Shuya Wei

AbstractRecently, a bowl containing charred suspected tea remains unearthed from the early stage of Warring States period tomb in Zoucheng City, Shandong Province, China. To identify the remains is significant for understanding the origin of tea and tea drinking culture. Scientific investigations of the remains were carried out by using calcium phytoliths analysis, Fourier transform infrared spectroscopy (FTIR), Gas Chromatograph Mass Spectrometer (GC/MS) and Thermally assisted hydrolysis—methylation Pyrolysis Gas Chromatography Mass Spectrometry (THM-Py-GC/MS) techniques. Modern tea and modern tea residue were used as reference samples. Through phytoliths analyses, calcium phytoliths identifiable from tea were determined in the archeological remains. The infrared spectra of the archaeological remains was found similar as modern tea residue reference sample. In addition, the biomarker compound of tea—caffeine was determined in the archaeological remains by THM-Py-GC/MS analysis. Furthermore, through GC/MS analysis, some compounds were found both in the archeological remains and the modern tea residue reference samples. Putting the information together, it can be concluded that the archaeological remains in the bowl are tea residue after boiling or brewing by the ancient.


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