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81.
A deep-cavity ‘mixed’ octahomotetraoxacalix[2]naphthalene[2]pyridine macrocycle has been synthesised and its single-crystal X-ray structure has been determined. Molecular modeling studies suggested that this macrocycle could be an effective host for guest aromatic diol(s) similar to Wang's methylazacalixpyridines. Binding constants were determined using 1H NMR chemical shifts changes and comparisons were made between the diols which were tested. 相似文献
82.
Lee Chuin Chen Md. Matiur Rahman Kenzo Hiraoka 《Journal of the American Society for Mass Spectrometry》2014,25(11):1862-1869
The heating of electrospray ion source under atmospheric pressure is limited to the normal boiling point of the solution. The boiling takes place when the vapor pressure of the liquid at a given temperature equals the ambient pressure. By using a high pressure ESI source, which has been developed previously in our laboratory, a stable electrospray ionization of super-heated aqueous solution is performed up to a solution temperature of 180°C. The ion source is pressurized with pure nitrogen to a maximum pressure of 11 atm, and it is coupled to a commercial mass spectrometer via a custom-made ion transport capillary. A booster pump with variable pumping speed is added to the pumping system to regulate the pressure in the first pumping stage at 1?~?1.3 Torr. High pressure mass spectrometry is performed on several peptides and proteins to demonstrate its application in the temperature-controlled thermally induced denaturation and dissociation. Graphical Abstract
? 相似文献
83.
A 1H NMR spectroscopic study of tetra-n-butylammonium halides (TBAX: X = Cl? , Br? or I? ) in CDCl3 solutions was conducted. Complexation studies of TBAX salts with different host molecules using 1H NMR in CDCl3 have previously revealed that the reference residual CHCl3 proton signal had been shifted downfield. The aim of the study was to quantify the extent of these chemical shift changes with TBAX salts. Linear concentration–chemical shift relationships in each case were obtained from the resulting titration plots obtained from the addition of the TBAX salts alone to CDCl3. Interactions in the solid state as determined by X-ray crystallography support the solution-state investigations indicating halide ion–chloroform proton interactions. 相似文献
84.
Anju Goyal Aditya Sharma Jasanpreet Kaur Sapna Kumari Madhukar Garg Rakesh K. Sindhu Md. Habibur Rahman Muhammad Furqan Akhtar Priti Tagde Agnieszka Najda Barbara Banach-Albiska Katarzyna Masternak Ibtesam S. Alanazi Hanan R. H. Mohamed Attalla F. El-kott Muddaser Shah Mousa O. Germoush Hamdan S. Al-malky Salman H. Abukhuwayjah Ahmed E. Altyar Simona G. Bungau Mohamed M. Abdel-Daim 《Molecules (Basel, Switzerland)》2022,27(3)
85.
Riju Khandaker M. Kamruzzaman M. Afrose R. Rahman M. Khan M. K. R. Liton M. N. H. Helal M. A. Anam T. K. Rahman M. M. 《Crystallography Reports》2020,65(6):968-979
Crystallography Reports - Transition metals doped FeS2 thin films are promising materials for optoelectronics, energy saving and storage applications. This is a first time report on the... 相似文献
86.
Muna E. Raypah Ahmad Fairuz Omar Jelena Muncan Musfirah Zulkurnain Abdul Rahman Abdul Najib 《Molecules (Basel, Switzerland)》2022,27(7)
Honey is a natural product that is considered globally one of the most widely important foods. Various studies on authenticity detection of honey have been fulfilled using visible and near-infrared (Vis-NIR) spectroscopy techniques. However, there are limited studies on stingless bee honey (SBH) despite the increase of market demand for this food product. The objective of this work was to present the potential of Vis-NIR absorbance spectroscopy for profiling, classifying, and quantifying the adulterated SBH. The SBH sample was mixed with various percentages (10–90%) of adulterants, including distilled water, apple cider vinegar, and high fructose syrup. The results showed that the region at 400–1100 nm that is related to the color and water properties of the samples was effective to discriminate and quantify the adulterated SBH. By applying the principal component analysis (PCA) on adulterants and honey samples, the PCA score plot revealed the classification of the adulterants and adulterated SBHs. A partial least squares regression (PLSR) model was developed to quantify the contamination level in the SBH samples. The general PLSR model with the highest coefficient of determination and lowest root means square error of cross-validation ( and ) was acquired. The aquaphotomics analysis of adulteration in SBH with the three adulterants utilizing the short-wavelength NIR region (800–1100 nm) was presented. The structural changes of SBH due to adulteration were described in terms of the changes in the water molecular matrix, and the aquagrams were used to visualize the results. It was revealed that the integration of NIR spectroscopy with aquaphotomics could be used to detect the water molecular structures in the adulterated SBH. 相似文献
87.
M. Sahedur Rahman 《Mikrochimica acta》2001,137(3-4):203-207
A sensitive and fairly selective quenchofluorimetric method for the determination of mercury ultra-trace with murexide (ammonium
purpurate) has been developed. The method is based on the instantaneous quenching action of the metal-ion upon the native
fluorescence of murexide [λex(max) = 360 nm; λem(max) = 445 nm] in the optimum pH range of 5.8 to 6.6 at room temperature (25±0.5) °C. The fluorescence quenching is collinear
in the range of 5 μg/L to 100 μg/L mercury. The developed method is very precise and accurate (RSD = 2.2% for 11 determination
of 50 μg/L Hg(II). Large excesses of more than 50 cations, anions and complexing agents were found to have no interference.
The developed method was successfully tested over synthetic mixtures of various compositions, certified reference materials
and factory effluents.
Received November 16, 1999. Revision March 30, 2001. 相似文献
88.
Organic perovskite has potential to replace organic dye as light absorber in solar cell since it possesses better optical absorption in visible region than organic dye. This work is concerned with the investigation of the influence of CH3NH3PbI3 perovskite dipping time on the performance of perovskite-sensitized solar cell (PSSC). The effect of the dipping time on the morphology and photoluminescence of the sample has also been investigated. It was found that the device achieved a power conversion efficiency (PCE) as high as 5.57 ± 0.4% at the optimum dipping time of 4 h. The highest PCE is due to the highest IPCE, lowest Rct and the longest carrier lifetime (τ). 相似文献
89.
Md. Mominur Rahman Md. Rezaul Islam Sheikh Shohag Md. Emon Hossain Md. Saidur Rahaman Fahadul Islam Muniruddin Ahmed Saikat Mitra Mayeen Uddin Khandaker Abubakr M. Idris Kumarappan Chidambaram Talha Bin Emran Simona Cavalu 《Molecules (Basel, Switzerland)》2022,27(5)
Obesity and diabetes are the most demanding health problems today, and their prevalence, as well as comorbidities, is on the rise all over the world. As time goes on, both are becoming big issues that have a big impact on people’s lives. Diabetes is a metabolic and endocrine illness set apart by hyperglycemia and glucose narrow-mindedness because of insulin opposition. Heftiness is a typical, complex, and developing overall wellbeing worry that has for quite some time been connected to significant medical issues in individuals, all things considered. Because of the wide variety and low adverse effects, herbal products are an important hotspot for drug development. Synthetic compounds are not structurally diverse and lack drug-likeness properties. Thus, it is basic to keep on exploring herbal products as possible wellsprings of novel drugs. We conducted this review of the literature by searching Scopus, Science Direct, Elsevier, PubMed, and Web of Science databases. From 1990 until October 2021, research reports, review articles, and original research articles in English are presented. It provides top to bottom data and an examination of plant-inferred compounds that might be utilized against heftiness or potentially hostile to diabetes treatments. Our expanded comprehension of the systems of activity of phytogenic compounds, as an extra examination, could prompt the advancement of remedial methodologies for metabolic diseases. In clinical trials, a huge number of these food kinds or restorative plants, as well as their bioactive compounds, have been shown to be beneficial in the treatment of obesity. 相似文献
90.