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101.
102.
N-Benzoyl-o-tolylhydroxylamine is shown to provide a virtually specific reagent for the spectrophotometric determination of vanadium. The reddish-violet complex formed with the reagent in 4–8 N hydrochloric acid after extraction with chloroform shows absorption maxima at 510 mm, and obeyes Beer's law from 0.5 to 10 μg with an optimum range of 2–10 μg; the percent relative error is 2.7. The sensitivity is 0.0108 μg V/cm2. The complex contains the metal and the reagent in a ratio of 1:2 and the dissociation constant is of the order of 10-9. 相似文献
103.
M. K. Das N. Ramamoorthy B. R. Sarkar R. S. Mani 《Journal of Radioanalytical and Nuclear Chemistry》1987,111(2):469-475
We have studied the feasibility of producing57Co (271.3 d) via the55Mn(, 2n)57Co reaction (55Mn–100%). The thick target yield of57Co in the 28 to 18 MeV energy region was measured as 3.87 Ci/Ah. However, the proximity and overlap of the excitation functions for (, n), (, 2n) and (, 3n) reactions on55Mn are such that the production of pure57Co in high yields free of58Co (70.8 d) and56Co (78.8 d) has not been feasible. We have also studied a new method for ancillary production of57Co via the reactions58Ni(, p)57Co and
during the course of producing62Zn by60Ni(, 2n)62Zn reaction. In this case the yield of57Co of reasonable purity has been up to 1 Ci/Ah. 相似文献
104.
N. R. Das P. S. Chakraborty S. N. Bhattacharyya 《Journal of Radioanalytical and Nuclear Chemistry》1977,36(2):419-425
Present investigation deals with neutron activation analysis of gold in some varieties of geological samples related to auriferous
quartz veins. A few plant specimens of the area were also analyzed. The gold contents in the rock samples as determined by
the destructive way of analysis vary in the range 10−5 to 10−7%. In case of plant samples, however, the non-destructive method of analysis of the plant ashes was followed and the concentration
of gold was found to be of the order of 10−5%. In plants, besides gold, some associated elements, such as La, Ce, Sm, Lu, Zr, Hf, Se, W, As and Sb were also identified. 相似文献
105.
Sudipta Jena Asit Ray Omprakash Mohanta Prabhat Kumar Das Ambika Sahoo Sanghamitra Nayak Pratap Chandra Panda 《Molecules (Basel, Switzerland)》2022,27(23)
Neocinnamomum caudatum (Lauraceae) plant is used in the traditional system of medicine and is considered a potential source of edible fruits, spices, flavoring agents and biodiesel. The leaves, bark and roots of the species are used by local communities for the treatment of inflammatory responses, such as allergies, sinusitis and urinary tract infections. However, there is no scientific evidence to support the molecular mechanism through which this plant exerts its anti-inflammatory effect. The aim of the current research was to characterize the chemical constituents of bark (NCB) and leaf (NCL) essential oil of N. caudatum and to elucidate its anti-inflammatory action in lipopolysaccharide (LPS)-treated RAW 264.7 cells. Essential oils extracted by hydrodistillation were further subjected to gas chromatography mass spectrometry (GC-MS) analysis. The major constituents in bark essential oil identified as β-pinene (13.11%), α-cadinol (11.18%) and α-pinene (10.99%), whereas leaf essential oil was found to be rich in β-pinene (45.21%), myrcene (9.97%) and α-pinene (9.27%). Treatment with NCB and NCL at a concentration of 25 µg/mL exerted significant anti-inflammatory activity by significantly reducing LPS-triggered nitric oxide (NO) production to 45.86% and 61.64%, respectively, compared to the LPS-treated group. In the LPS-treated group, the production of proinflammatory cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1β, decreased after treatment with essential oil, alleviating the mRNA levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2. The essential oil also inhibited the production of intracellular ROS and attenuated the depletion of mitochondrial membrane potential in a concentration-dependent manner. Pretreatment with NCB also reduced nuclear factor kappa-B (NF-κB)/p65 translocation and elevated the levels of endogenous antioxidant enzymes in LPS-induced macrophages. The present findings, for the first time, demonstrate the anti-inflammatory potential of both bark and leaf essential oils of N. caudatum. The bark essential oil exhibited a significantly more important anti-inflammatory effect than the leaf essential oil and could be used as a potential therapeutic agent for the treatment of inflammatory diseases. 相似文献
106.
Navara Tanweer Fazal-Ur-Rehman Qazi Gotam Das Afreen Bilgrami Sakeenabi Basha Naseer Ahmed Hammam Ahmed Bahammam Sarah Ahmed Bahammam Syed Nahid Basheer Ali A. Assiry Mohmed Isaqali Karobari Abdul Samad Khan Artak Heboyan 《Molecules (Basel, Switzerland)》2022,27(15)
Erosive beverages cause dissolution of natural teeth and intra-oral restorations, resulting in surface characteristic changes, particularly roughness and degradation. The purpose of this study was to evaluate the surface roughness and topography of a dental ceramic following immersion in locally available erosive solutions. A total of 160 disc specimens of a nano-fluorapatite type ceramic (12 mm diameter and 2 mm thickness) were fabricated and equally distributed into two groups (n = 80) and then evenly distributed among the following five testing groups (n = 16): lemon juice, citrate buffer solution, 4% acetic acid, soft cola drink, and distilled water which served as a control. The surface roughness (Ra) and topography were evaluated using a profilometer and scanning electron microscope at baseline, 24 h, 96 h, and 168 h respectively. Data were analyzed using ANOVA and Tukey’s multiple comparisons (p ≤ 0.05). Surface changes were observed upon exposure to all acidic beverages except distilled water. Amongst all immersion media, 4% acetic acid produced the most severe surface roughness across all time periods (i.e., baseline, 24 h, 96 h, and 168 h). A statistically significant difference in the surface roughness values between all immersion media and across all four time intervals was observed. Erosive agents had a negative effect on the surface roughness and topography of the tested ceramic. The surface roughness increased with increased storage time intervals. 相似文献
107.
Chiranjit Mahato Sneha Menon Abhishek Singh Syed Pavel Afrose Jagannath Mondal Dibyendu Das 《Chemical science》2022,13(32):9225
Herein, we report that short peptides are capable of exploiting their anti-parallel registry to access cross-β stacks to expose more than one catalytic residue, exhibiting the traits of advanced binding pockets of enzymes. Binding pockets decorated with more than one catalytic residue facilitate substrate binding and process kinetically unfavourable chemical transformations. The solvent-exposed guanidinium and imidazole moieties on the cross-β microphases synergistically bind to polarise and hydrolyse diverse kinetically stable model substrates of nucleases and phosphatase. Mutation of either histidine or arginine results in a drastic decline in the rate of hydrolysis. These results not only support the argument of short amyloid peptides as the earliest protein folds but also suggest their interactions with nucleic acid congeners, foreshadowing the mutualistic biopolymer relationships that fueled the chemical emergence of life.Amyloid based short peptide assemblies use antiparallel registry to expose multiple catalytic residues to bind and cleave kinetically stable phosphoester bonds of nucleic acid congeners, foreshadowing interactions of protein folds with nucleic acids. 相似文献
108.
With the advent of single-cell RNA-sequencing (scRNA-seq), it is possible to measure the expression dynamics of genes at the single-cell level. Through scRNA-seq, a huge amount of expression data for several thousand(s) of genes over million(s) of cells are generated in a single experiment. Differential expression analysis is the primary downstream analysis of such data to identify gene markers for cell type detection and also provide inputs to other secondary analyses. Many statistical approaches for differential expression analysis have been reported in the literature. Therefore, we critically discuss the underlying statistical principles of the approaches and distinctly divide them into six major classes, i.e., generalized linear, generalized additive, Hurdle, mixture models, two-class parametric, and non-parametric approaches. We also succinctly discuss the limitations that are specific to each class of approaches, and how they are addressed by other subsequent classes of approach. A number of challenges are identified in this study that must be addressed to develop the next class of innovative approaches. Furthermore, we also emphasize the methodological challenges involved in differential expression analysis of scRNA-seq data that researchers must address to draw maximum benefit from this recent single-cell technology. This study will serve as a guide to genome researchers and experimental biologists to objectively select options for their analysis. 相似文献
109.
110.
Structural Chemistry - Under density functional theory (DFT), a first principle analysis is conducted to pure, boron (B)- and phosphorus (P)-doped silicon-germanium nanosheets. It has been revealed... 相似文献