查看更多>>摘要：Carbon nanotubes have garnered significant interest due to their promising applications and facile synthesis. This study highlights the applications of CNTs in the field of hydrogen production and storage. Hydrogen energy attracted researchers because of its clean, renewable and sustainable energy with low impact on the environment around the globe. It is expected hydrogen energy systems replace the prevailed fossil fuels in the coming years. Hydrogen systems exhibit many disadvantages such as production costs and storage aspects. CNTs have the greater capability as support for the manufacture of effectual contrasting catalysts in hydrogen production systems. The main focus of this article is their different manufacturing methods along with their models and the purification techniques to obtain the best quality CNT’s and then use them in different applications. Some of them are best suited to provide the quantity while on the other hand, some can provide the better quality of CNT’s. Moreover, by using different techniques the different classifications of CNT’s like SWCNT and MWCNTs can be obtained according to our needs and preferences. This paper reviewed the methodologies used in the production and storage of hydrogen. Our concern is basically to review the dares in production and storage of hydrogen compare their results, to study recent developments in modifications of CNTs to increase production and storage of hydrogen.
查看更多>>摘要：Natural compounds are very much important as they can cure diseases naturally without harmful effects from natural sources. Coumarin is also a natural compound and a large number of coumarins almost 1300 coumarins have been recognized from natural sources, mainly from green plants. Substitution on coumarins is responsible for their therapeutic, biochemical, and pharmacological applications. Coumarins are present in plants and can also be prepared in the laboratory. Coumarin, a drug is used in heat problems as it is an anti-coagulant i.e., it stops and helps to cure blood clots of blood vessels. This article is based upon the investigation of the absorption spectra of coumarin and its derivatives. The absorption spectra involve the study of UV–Visible spectroscopy and fluorescence spectroscopy. Solvatochromic shifts and the effects of the salts on fluorescence spectra and UV–Visible spectra will also be studied.
Ghazal HebaOthman Hanan A.Hassabo Ahmed G.Zayed Menna...
22页
查看更多>>摘要：An eco-friendly process was used to impart multifunctional properties to cotton fabric using Citrus Sinensis peel (orange peel) extract. Two solvents have been used to prepare the extract, namely water and ethanol. Both extractions have been used as reducing and stabilizing agents in the synthesis of silver and zinc oxide nanoparticles. Prepared extracts and synthesized nanoparticles have been characterized using different techniques such as total phenol content, antioxidant activity, particle size analyzer, Fourier transform infrared, transmission electronic microscopy, and X-ray diffraction. The cotton fabric was treated with orange peel extraction, silver nanoparticles, and zinc oxide nanoparticles loaded with chitosan. The treated cotton samples were characterized by scanning electron microscopy, UPF value, antimicrobial activity, mosquito repellent effect, and self-cleaning properties.
查看更多>>摘要：Microchannel increases the rapidity of mixing and mass transfer in chemical reactions so the production rate enhances. In this investigation, a new basic ionic liquid pyridine base was stabilized on the solid base, afterward was utilized for the methyl esters production in microchannel. The major nominal variables to optimize the conditions for achieving a maximum yield of biodiesel were: catalyst concentration, methanol-to-oil molar ratio and reaction time (injection time) and microchannel type (M1, M2 and M3) as categorical factor. Using response surface methodology (Box–Behnken design), experiments were designed. By evaluating the outcomes, the optimum point was earned. The ideal conditions according to the empirical model were: methanol/oil molar ratio?=?10.9, reaction time?=?1.74?min (residence time?=?1.16?s), catalyst dosage (% wt.)?=?3.49 and M1 microchannel type. The model's prediction for the produced methyl ester yield at optimum conditions was 97%. The experimental result of 95.2% for the optimum condition indicated excellent accuracy of the model. The catalyst was reused six times at the best condition. With great results, it ultimately yielded 88.3% at the sixth run, which shows the significant strength of the catalyst. Moreover, controlled by the optimal conditions for M1 microchannel, the synthesized ionic liquid was used. Accompanied by the same weight percent added to the oil, with three repetitions and average biodiesel yield of 98.85% was gained. It should also be mentioned that under best conditions, the employment of selected M1 microchannel instead of the straight tube increased the pressure drop by up to 3.6 times.Graphic abstract
查看更多>>摘要：The main focus of this study is to introduce and validate an electromembrane extraction (EME) method along with HPLC–UV analysis to determine theophylline in the plasma and urine. The main parameters affecting the extraction process such as type of supported liquid membrane organic solvent, donor and acceptor pH, extraction time and voltage were examined. Under optimal conditions, theophylline was extracted from the sample solution at pH?=?9 to the acceptor solution at pH?=?13, and as the extraction driving force, a voltage of 50?V was used for 10?min. Considering the main phenomena in EME, a computational model was used to predict the recovery ratio of EME systems. At this voltage and extraction time, the simulation was performed for various pH of the sample and acceptor solutions. Results revealed that the optimum working condition was computed to be when the sample and acceptor solution pH is around 9.5–10 and, 12.5–13, respectively, which are in acceptable agreement with experimental results. Under these conditions, the calibration curve is linear in the range of 50–500?ng/ml with a relative standard deviation of less than 7.0%. The limit of detection and limit of quantitation were 15 and 50?ng/ml, respectively. The enrichment factor and extraction recovery calculated for this method were 42 and 28%, respectively. The developed method was used for the plasma and urine with relative recovery of 95.1% and 69.2%, respectively. Moreover, the relative standard deviation of the biological samples was 4.4% and 3.9% for the plasma and urine, respectively.
查看更多>>摘要：A novel type of poly(St–SSS–APEG) (SAS) copolymer was prepared by graft polymerization with corn starch (St) as the backbone chain and with sodium p-styrene sulfonate (SSS) and allyl polyethylene glycol (APEG-1000) as side chains in aqueous solution. This graft copolymer can serve as an effective dispersing agent for multi-walled carbon nanotubes (MWCNTs) and offers excellent dispersion performance. The primary focus of this investigation was the dispersing behavior of the graft copolymer and the optimization of the ratio between SAS and MWCNTs. For comparisons, poly(St–SSS) (SS) and poly(St–APEG) (SA) were, respectively, synthesized under the same conditions. The structures of SAS, SS, and SA were characterized via Fourier-transform infrared (FT-IR) spectroscopy. The morphologies of corn starch and modified corn starch were characterized by scanning electron microscopy (SEM), while the crystal form of the starch before and after this modification reaction was evaluated by X-ray diffraction (XRD). In addition, the morphology of the dispersed MWCNTs was observed by transmission electron microscopy (TEM). In addition, the dispersion properties and the optimum mass ratio between SAS and MWCNTs were analyzed by zeta potential measurements and ultraviolet–visible–near infrared (UV–Vis–NIR) spectroscopy. It was found that the SAS was more effective in decreasing the aggregative tendency of MWCNTs in water than SS and SA.Graphic abstract Based on a simple graft polymerization reduction, we have successfully prepared a novel type of poly(St–SSS–APEG) (SAS) copolymer with corn starch (St) as the backbone chain and with sodium p-styrene sulfonate (SSS) and allyl polyethylene glycol (APEG-1000) as side chains in aqueous solution, which can serve as an effective dispersing agent for multi-walled carbon nanotubes (MWCNTs) and offer excellent dispersion performance. It was demonstrated that the dispersion ability of SAS is due to the synergic effects of electrostatic repulsion and steric hindrance.
查看更多>>摘要：The present study introduces an active macroscopic mixing device for aqueous sanitizer preparation. It operates on a piezoelectrically actuated oscillating cantilever beam appropriate for disparate feature liquid–liquid mixing. A piezoelectric actuated cantilever beam at the third bending mode vibration frequency produces extreme vibrations when excited by a suitable voltage. Potent mixing occurs as the robust vibration energy is sent from the beam to the container’s test liquid. In this work, different glycerol concentrations were mixed with deionized (DI) water and ethanol at 25 ℃. The mixer’s performance to mix DI water–glycerol, ethanol–glycerol, and DI water–ethanol–glycerol considered a sanitizer was tested. The sanitizer mixture’s measured density, viscosity, and surface tension values were 0.7502?g?cm?3, 1.8906 cp, 34.7893 dyne cm?1, respectively. The measured aqueous-based glycerol mixture’s density and viscosity values were validated with the computed values by previous researcher’s models and formulas. The observed density reading of the aqueous-based 25% glycerol concentration mixture agreed with the estimated value of a density model having?±?1.1290% deviation.
Mohammed Mohammed Q.Ismail Hani K.Alesary Hasan F.Barton Stephen...
15页
查看更多>>摘要：The work herein describes the electrochemical detection of heavy metal ions, specifically cadmium and lead. The introduction and modification of functional groups such as Schiff bases leads to an enhanced sensitivity of the electrode to analytes. In this study, a platinum electrode has, for the first time, been modified with poly(3,4-ethylenedioxythiophene) (PEDOT/Schiff base) in CH2Cl2 containing Bu4NPF6 to detect cadmium(II) and lead(II) ions. The structures and morphologies of the polymer coatings were characterised via Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The electrochemical synthesis and redox state response in monomer-free synthesised films have been studied via cyclic voltammetry. Moreover, the effect of scan rate on the electrochemical behaviour of the modified electrodes was also studied. The voltammetric findings have been used to calculate the surface coverage required for the polymer films and the stability of polymer electrodes in the monomer-free solutions. Square wave voltammetry was applied for the determination of cadmium(II) and lead(II) ion concentrations and to assess the effects of pH on aqueous samples. The limits of detection for the modified electrode for cadmium(II) and lead(II) were found to be 0.95?μg?L?1 and 1.84?μg? L?1, respectively. These findings revealed that modified films can be considered good candidates for application in electrochemical detection devices.
查看更多>>摘要：The effect of aqueous extract of leaves of Morinda tinctoria?on the corrosion inhibition of aluminium in alkaline medium was studied by weight loss and electrochemical methods such as electrochemical impedance spectroscopy and potentiodynamic polarization measurements. The change in different parameters like concentrations of inhibitor, sodium hydroxide, halide ions, temperatures and immersion time was carried out to determine the longevity and stability of the inhibitor. Increase in the immersion time, alkaline concentration and temperature increases the inhibition efficiency. Investigation of temperature studies reveals that the inhibitor follows chemisorption behaviour towards corrosion protection. Temkin adsorption isotherm was obeyed throughout the corrosion inhibition process. The added halide additives produced tremendous changes in the inhibition system. The recorded scanning electron microscopy for the aluminium metal before and after the addition of inhibitor in the alkaline medium confirmed the adsorption of inhibitor molecules on the metal surface. The investigation proves that the inhibitor works perfectly against the corrosion of metal and suitable for corrosion inhibition process.Graphic Abstract
查看更多>>摘要：α-difluoromethylornithine (DFMO) is an anti-Trypanosoma Brucei agent that is approved for the medication of sleeping sickness and is widely licensed for the treatment and diminishing the unwanted facial hair (hirsutism). The suggested work provides a comprehensive analytical protocol for investigating the fluorescence properties of the reaction product between DFMO and ninhydrin/phenylacetaldehyde reagent. In this approach, all reaction conditions such as reagent volumes, buffer volume, pH value, heating time and heating temperature were carefully handled and optimized. The formed product was measured spectrofluorimetrically at the emission wavelength of 483?nm upon its excitation at the wavelength of 388?nm. For accuracy, linearity, sensitivity, robustness and preciseness of the method, the suggested approach was validated and verified according to ICH guiding principles. Also, the proposed work offered a unique selectivity for the determination of DFMO with agreeable recovery values in different brands of commercial cream samples without interference from cream excipients. Lastly, the suggested approach was assured to be successful in the estimation of DFMO in human urine specimens with agreeable recovery results.
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