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51.
Asghar Mardani Mohammad Reza Afshar Mogaddam Mir Ali Farajzadeh Ali Mohebbi Mahboob Nemati Mohammadali Torbati 《Journal of separation science》2020,43(18):3674-3682
A sample pretreatment method based on the combination of a three‐phase solvent extraction system and deep eutectic solvent‐based dispersive liquid–liquid microextraction has been introduced for the extraction of four organochlorine pesticides in cocoa samples before their determination by gas chromatography‐electron capture detection. A mixture of sodium chloride, acetonitrile, and potassium hydroxide solution is added to cocoa bean or powder. After vortexing and centrifugation of the mixture, the collected upper phase (acetonitrile) is removed and mixed with a few microliters of N,N‐diethanol ammonium chloride: pivalic acid deep eutectic solvent. Then it is rapidly injected into deionized water and a cloudy solution is obtained. Under optimum conditions, the limits of detection and quantification were found to be 0.011‐0.031 and 0.036‐0.104 ng/g, respectively. The obtained extraction recoveries varied between 74 and 92%. Also, intra‐ (n = 6) and interday (n = 4) precisions were less than or equal to 7.1% for the studied pesticides at a concentration of 0.3 ng/g of each analyte. The suggested method was applied to determine the studied organochlorine pesticide residues in various cocoa powders and beans gathered from groceries in Tabriz city (Iran) and aldrin and dichlobenil were found in some of them. 相似文献
52.
Kai Chen Gang Huang Jin‐Ling Ma Jin Wang Dong‐Yue Yang Xiao‐Yang Yang Yue Yu Xin‐Bo Zhang 《Angewandte Chemie (International ed. in English)》2020,59(38):16661-16667
The lithium (Li)–air battery has an ultrahigh theoretical specific energy, however, even in pure oxygen (O2), the vulnerability of conventional organic electrolytes and carbon cathodes towards reaction intermediates, especially O2?, and corrosive oxidation and crack/pulverization of Li metal anode lead to poor cycling stability of the Li‐air battery. Even worse, the water and/or CO2 in air bring parasitic reactions and safety issues. Therefore, applying such systems in open‐air environment is challenging. Herein, contrary to previous assertions, we have found that CO2 can improve the stability of both anode and electrolyte, and a high‐performance rechargeable Li–O2/CO2 battery is developed. The CO2 not only facilitates the in situ formation of a passivated protective Li2CO3 film on the Li anode, but also restrains side reactions involving electrolyte and cathode by capturing O2?. Moreover, the Pd/CNT catalyst in the cathode can extend the battery lifespan by effectively tuning the product morphology and catalyzing the decomposition of Li2CO3. The Li–O2/CO2 battery achieves a full discharge capacity of 6628 mAh g?1 and a long life of 715 cycles, which is even better than those of pure Li–O2 batteries. 相似文献
53.
Guozhen Liu Long Cheng Guining Chen Feng Liang Gongping Liu Wanqin Jin 《化学:亚洲杂志》2020,15(15):2364-2370
Mixed matrix membranes (MMMs) made from inorganic fillers and polymers is a kind of promising candidate for gas separation. In this work, two‐dimensional MXene nanosheets were synthesized and incorporated into a polyether‐polyamide block copolymer (Pebax) matrix to fabricate MMM for CO2 capture. The physicochemical properties of MXene nanosheets and MXene/Pebax membranes were studied systematically. The introduction of MXene nanosheets provided additional molecular transport channels and meanwhile enhanced the CO2 adsorption capacity, thereby enhancing both the CO2 peremance and CO2/N2 selectivity of Pebax membrane. The optimized MXene/Pebax membrane with a MXene loading of 0.15 wt % displayed a high separation performance with a CO2 permeance of 21.6 GPU and a CO2/N2 selectivity of 72.5, showing potential application in CO2 capture. 相似文献
54.
Dr. Renata Avena Maia Felipe Lopes Oliveira Prof. Vincent Ritleng Prof. Qiang Wang Dr. Benoît Louis Prof. Pierre Mothé Esteves 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(30):8048-8055
Covalent organic frameworks (COFs) RIO-13, RIO-12, RIO-11, and RIO-11m were investigated towards their CO2 capture properties by thermogravimetric analysis at 1 atm and 40 °C. These microporous COFs bear in common the azine backbone composed of hydroxy-benzene moieties but differ in the relative number of hydroxyl groups present in each material. Thus, their sorption capacities were studied as a function of their textural and chemical properties. Their maximum CO2 uptake values showed a strong correlation with an increasing specific surface area, but that property alone could not fully explain the CO2 uptake data. Hence, the specific CO2 uptake, combined with DFT calculations, indicated that the relative number of hydroxyl groups in the COF backbone acts as an adsorption threshold, as the hydroxyl groups were indeed identified as relevant adsorption sites in all the studied COFs. Additionally, the best performing COF was thoroughly investigated, experimentally and theoretically, for its CO2 capture properties in a variety of CO2 concentrations and temperatures, and showed excellent isothermal recyclability up to 3 cycles. 相似文献
55.
Ao Yu Guoming Ma Jintian Jiang Yajing Hu Mingming Su Wangtao Long Shixin Gao Dr. Hsien-Yi Hsu Dr. Ping Peng Prof. Fang-Fang Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(40):10405-10412
Inspired by the spongy bone structures, three-dimensional (3D) sponge-like carbons with meso-microporous structures are synthesized through one-step electro-reduction of CO2 in molten carbonate Li2CO3−Na2CO3−K2CO3 at 580 °C. SPC4-0.5 (spongy porous carbon obtained by electrolysis of CO2 at 4 A for 0.5 h) is synthesized with the current efficiency of 96.9 %. SPC4-0.5 possesses large electrolyte ion accessible surface area, excellent wettability and electronical conductivity, ensuring the fast and effective mass and charge transfer, which make it an advcanced supercapacitor electrode material. SPC4-0.5 exhibits a specific capacitance as high as 373.7 F g−1 at 0.5 A g−1, excellent cycling stability (retaining 95.9 % of the initial capacitance after 10000 cycles at 10 A g−1), as well as high energy density. The applications of SPC4-0.5 in quasi-solid-state symmetric supercapacitor and all-solid-state flexible devices for energy storage and wearable piezoelectric sensor are investigated. Both devices show considerable capacitive performances. This work not only presents a controllable and facile synthetic route for the porous carbons but also provides a promising way for effective carbon reduction and green energy production. 相似文献
56.
G. Brunner 《Isotopes in environmental and health studies》2013,49(12):420-424
Modern radiometric analytics demands a complex consideration of nuclear and electron shell processes, if more pretentious aims are envisaged. As an example the small variation of decay rates of radionuclides presents possibilities for information on chemical situations of decaying atoms. In principle this phenomenon is well known since many years, but now the situation is such that, e.g. in 99mTc internal conversion, a full agreement of the difficult experiments and the respective theory was established. The secondary emission of X-rays as a consequence of high excitation of electron shells in combination with nuclear transitions supplies another example for a methodical progress of radiometry. Investigations on 51Cr as an electron capture nuclide have shown that chemically induced variations of the Kα to Kβ X-ray intensity ratio is at least qualitatively understood. 相似文献
57.
《Analytical letters》2012,45(11):1005-1012
Abstract A procedure for the determination of propoxyphene (α-d-dimethylamino-1, 2 -diphenyl-3 -methyl-2 -propionoxybutane) in plasma is reported. The method is based on the electron capture characteristics of propoxyphene. The plasma is rendered basic to generate the free amine and extracted with ether. The extract is analyzed by gas chromatography using a 4 foot OV-225 column. An internal standard of imipramine hydrochloride is used to quantitate the propoxyphene. This internal standard is carried through the entire procedure. The ratio of the peak heights of propoxyphene to imipramine is compared to ratios obtained from standards placed in plasma and treated in the same manner as the samples. Six subjects were given propoxyphene at different time intervals, and the data are presented concerning these subjects. 相似文献
58.
A multiscale information measure (MIM), calculable from per-pixel wavelet coefficients, but relying on global statistics of synthetic aperture radar (SAR) image, is proposed. It fully exploits the variations in speckle pattern when the image resolution varies from course to fine, thus it can capture the intrinsic texture of the scene backscatter and the texture due to speckle simultaneously. Graph spectral segmen- tation methods based on MIM and the usual similarity measure are carried out on two real SAR images. Experimental results show that MIM can characterize texture information of SAR image more effectively than the commonly used similarity measure. 相似文献
59.
60.
An alternate and a new interpretation is given for the event attributed to a magnetic monopole by Price and coworkers found
in an emulsion plastic sandwich stack flown from Sioux City, Iowa, USA on 18 September 1973. The electron pick-up and stripping
cross-sections of nuclei ofZ∼70–80 andv∼0.6–0.7c in Lexan polycarbonate are calculated using the formulae given by Nikolaev. It is shown that the corresponding mean free
paths are of the order of thickness (∼250μ) of Lexan plastic sheets used by them. In such a case asnapshot of these processes is believed to have been observed in plastic sheets. Monte-Carlo simulations of the event have been made
for three values of charges at the top of the main Lexan stack, namelyZ=83, 78 and 70 respectively. The event is thus interpreted as a cosmic ray nucleus ofZ=70–83 andv=0.6–0.7c losing and capturing electrons (mainly the latter) as it passes through the stack. The probability of the occurrence of such
an event is estimated by several methods. 相似文献