quantitative estimation
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2022 ◽  
Vol 23 (2) ◽  
pp. 889
Author(s):  
Atsuya Matsui ◽  
Jean-Pierre Bellier ◽  
Takeshi Kanai ◽  
Hiroki Satooka ◽  
Akio Nakanishi ◽  
...  

The most common type of dementia, Alzheimer’s disease, is associated with senile plaques formed by the filamentous aggregation of hydrophobic amyloid-β (Aβ) in the brains of patients. Small oligomeric assemblies also occur and drugs and chemical compounds that can interact with such assemblies have attracted much attention. However, these compounds need to be solubilized in appropriate solvents, such as ethanol, which may also destabilize their protein structures. As the impact of ethanol on oligomeric Aβ assembly is unknown, we investigated the effect of various concentrations of ethanol (0 to 7.2 M) on Aβ pentameric assemblies (Aβp) by combining blue native-PAGE (BN-PAGE) and ambient air atomic force microscopy (AFM). This approach was proven to be very convenient and reliable for the quantitative analysis of Aβ assembly. The Gaussian analysis of the height histogram obtained from the AFM images was correlated with band intensity on BN-PAGE for the quantitative estimation of Aβp. Our observations indicated up to 1.4 M (8.3%) of added ethanol can be used as a solvent/vehicle without quantitatively affecting Aβ pentamer stability. Higher concentration induced significant destabilization of Aβp and eventually resulted in the complete disassembly of Aβp.


Author(s):  
Sehrish Akram ◽  
Arshad Mehmood ◽  
Sajida Noureen ◽  
Maqsood Ahmed

Thermal-induced transformation of glutamic acid to pyroglutamic acid is well known. However, confusion remains over the exact temperature at which this happens. Moreover, no diffraction data are available to support the transition. In this article, we make a systematic investigation involving thermal analysis, hot-stage microscopy and single-crystal X-ray diffraction to study a one-pot thermal transition of glutamic acid to pyroglutamic acid and subsequent self-cocrystallization between the product (hydrated pyroglutamic acid) and the unreacted precursor (glutamic acid). The melt upon cooling gave a robust cocrystal, namely, glutamic acid–pyroglutamic acid–water (1/1/1), C5H7NO3·C5H9NO4·H2O, whose structure has been elucidated from single-crystal X-ray diffraction data collected at room temperature. A three-dimensional network of strong hydrogen bonds has been found. A Hirshfeld surface analysis was carried out to make a quantitative estimation of the intermolecular interactions. In order to gain insight into the strength and stability of the cocrystal, the transferability principle was utilized to make a topological analysis and to study the electron-density-derived properties. The transferred model has been found to be superior to the classical independent atom model (IAM). The experimental results have been compared with results from a multipolar refinement carried out using theoretical structure factors generated from density functional theory (DFT) calculations. Very strong classical hydrogen bonds drive the cocrystallization and lend stability to the resulting cocrystal. Important conclusions have been drawn about this transition.


Author(s):  
Haichao Lv ◽  
Xiankun Huang ◽  
Lixia Kang ◽  
Yongzhong Liu

Abstract The capacity fading of lithium-ion batteries (LIBs) is reported by a linear dependency followed by a nonlinear ageing process, where the former is dominated by solid electrolyte interphase formation and reformation (SEI and SEI-re), while the latter is by lithium plating. In this work, a two-stage model is developed to quantitatively predict the turning point during the capacity fading of LIBs, which couples the electrochemical and thermal models accounting for SEI, SEI-re and lithium plating. Accordingly, a quantitative evaluation method of the turning point is proposed by attributing the transition of the capacity fading to the balance of consumption of active lithium for SEI growth and lithium plating per cycle in the two stages. The characteristics of capacity fading of LIBs are quantitatively analyzed under various operation conditions and design parameters. An NCM111/graphite battery is used to validate the proposed model. The results shows the validity of the proposed model. The turning points of the capacity fading processes are influenced by operation and design parameters of LIBs, where lithium plating or SEI growth reign. According to the effect on the turning point, the order of significance of the factors are charging current, charging cut-off voltage, temperature and N/P ratio, respectively.


Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 546
Author(s):  
Klytaimnistra Katsara ◽  
Konstantina Psatha ◽  
George Kenanakis ◽  
Michalis Aivaliotis ◽  
Vassilis M. Papadakis

Raman spectroscopy is a well-defined spectroscopic technique sensitive to the molecular vibrations of materials, since it provides fingerprint-like information regarding the molecular structure of the analyzed samples. It has been extensively used for non-destructive and label-free cell characterization, particularly in the qualitative and quantitative estimation of amino acids, lipids, nucleic acids, and carbohydrates. Lymphoma cell classification is a crucial task for accurate and prompt lymphoma diagnosis, prognosis, and treatment. Currently, it is mostly based on limited information and requires costly and time-consuming approaches. In this work, we are proposing a fast characterization and differentiation methodology of lymphoma cell subtypes based on Raman spectroscopy. The study was performed in the temperature range of 15–37 °C to identify the best cell measurement conditions. The proposed methodology is fast, accurate, and requires minimal sample preparation, resulting in a potentially promising, non-invasive strategy for early and accurate cell lymphoma characterization.


Author(s):  
Harini R ◽  
Chandramohan A

The escalating problem of obesity has become a cause of great concern in the world today as it leads to adverse effects on human health, including cardiovascular diseases, cancer etc. The major causes of obesity may be attributed to sedentary lifestyle and bad food habits. Conventional modalities to tackle obesity are not free from side-effects. Urgency of a novel, nontoxic means needs to be developed to control obesity. In this study we aim to screen the phytochemical compounds of Camellia Sinensis and evaluate its antiobesity and antioxidant effects. The methanolic extract of Camellia Sinensis was analyzed for its phytochemical screening and assayed for its in-vitro activity against pancreatic lipase, its antioxidant potential and quantitative estimation of flavonoids and phenolics were done. The methanolic extract of Camellia Sinensis strongly inhibited pancreatic lipase by 63% and it also possesses a strong antioxidant effect and there was a significant positive correlation between phenolics, flavonoids and with alkaloid contents. From these results, it could be concluded that methanolic extracts of Camellia Sinensis possesses antipancreatic lipase compounds. It also possesses antioxidant effect. It is suggested that the phytochemical compounds from there plants may be applied for the prevention and treatment of obesity or hyperlipidemia. Keywords: Obesity, Camellia Sinensis, Pancreatic lipase, Antioxidant, Phenolic


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