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81.
Paula S. Farag Magdy M. Hemdan Amira A. El-Sayed 《Journal of heterocyclic chemistry》2020,57(9):3428-3441
A series of new 1,2,4-triazole-3-thiones were synthesized by calm, benign, no risk, eco-friendly, and energy efficient sequential reaction methodology like grinding and ultrasonic (US). In addition, 1,2,4-triazoles were prepared under conventional method and comparative study was done. The synthesized 1,2,4-triazoles were complexed with Ni(II) to produce nanoparticles complexes (NPC's) with average particle size vary from 55 to 100 nm (using scanning electron microscope technique) with good yields via both US and conventional techniques. X-ray diffraction technique and spectra analysis techniques were used to confirm the square planer geometry of the synthesized NPC's. Antimicrobial activity of the prepared 1,2,4-triazoles and their nickel complexes were studied which evaluated a high activity with complexes instead their triazoles. 相似文献
82.
The new scandium(III) carbodiimides Sc2(CN2)3 and Sc2O2(CN2) were prepared by solid-state metathesis reactions between Li2(CN2) and ScCl3 and, regarding Sc2O2(CN2), Sc2O3 was added. The X-ray powder diffraction pattern refinements lead to a trigonal-rhombohedral (R3 c) crystal system for Sc2(CN2)3 and to an orthorhombic (Immm) crystal system for Sc2O2(CN2). The structure of Sc2(CN2)3 is isotypic to the well-known rare earth carbodiimides RE2(CN2)3 with the smaller cations RE = Tm, Yb, and Lu, whereas Sc2O2(CN2) is not isotypic to the known RE2O2(CN2) (RE = Y, La, Ce–Gd, except Pm) compounds. Both crystal structures are represented by layered arrangements of scandium, respectively scandium and oxide, alternating with carbodiimide layers. 相似文献
83.
Simon Ludwanowski Dr. Meral Ari Karsten Parison Somar Kalthoum Paula Straub Nils Pompe Prof. Dr. Stefan Weber Priv.-Doz. Dr. Michael Walter Prof. Dr. Andreas Walther 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(58):13203-13212
Arylazopyrazoles are an emerging class of photoswitches with redshifted switching wavelength, high photostationary states, long thermal half-lives and facile synthetic access. Understanding pathways for a simple modulation of the thermal half-lives, while keeping other parameters of interest constant, is an important aspect for out-of-equilibrium systems design and applications. Here, it is demonstrated that the thermal half-life of a water-soluble PEG-tethered arylazo-bis(o-methylated)pyrazole (AAP) can be tuned by more than five orders of magnitude using simple pH adjustment, which is beyond the tunability of azobenzenes. The mechanism of thermal relaxation is investigated by thorough spectroscopic analyses and density functional theory (DFT) calculations. Finally, the concepts of a tunable half-life are transferred from the molecular scale to the material scale. Based on the photochromic characteristics of E- and Z-AAP, transient information storage is showcased in form of light-written patterns inside films cast from different pH, which in turn leads to different times of storage. With respect to prospective precisely tunable materials and time-programmed out-of-equilibrium systems, an externally tunable half-life is likely advantageous over changing the entire system by the replacement of the photoswitch. 相似文献
84.
Dr. Paula Morales Dr. Gemma Navarro Marc Gómez-Autet Laura Redondo Prof. Dr. Javier Fernández-Ruiz Dr. Laura Pérez-Benito Dr. Arnau Cordomí Prof. Dr. Leonardo Pardo Prof. Dr. Rafael Franco Dr. Nadine Jagerovic 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(68):15839-15842
Single chemical entities with potential to simultaneously interact with two binding sites are emerging strategies in medicinal chemistry. We have designed, synthesized and functionally characterized the first bitopic ligands for the CB2 receptor. These compounds selectively target CB2 versus CB1 receptors. Their binding mode was studied by molecular dynamic simulations and site-directed mutagenesis. 相似文献
85.
Ana Ediléia Barbosa Pereira Leal Ana Paula de Oliveira Raira Feitosa dos Santos Juliana Mikaelly Dias Soares Erica Martins de Lavor Michelle Cruz Pontes 《Natural product research》2020,34(7):995-1001
AbstractEthanol extracts of different parts of Passiflora cincinnata were obtained by maceration. The total phenolic and flavonoid contents were evaluated. The antioxidant activities were determined by β-carotene-linoleic acid bleaching test, 2,2-diphenyl-1-picrylhydrazil (DPPH), and 2,2’-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging. The crude ethanol stem extract showed the highest amount of total polyphenols (45.53?mg gallic acid equivalent/g) while the highest total flavonoid contents (1.42?mg of quercetin equivalent/g) were observed in the leaf extract. The lowest IC50 (25.65?μg/ml) by the DPPH method was observed for the stem extract. The ABTS method showed a significant antioxidant activity for all investigated extracts. The secondary metabolite composition of ethanol extracts was assessed by HPLC-DAD-MS/MS analysis, leading to the identification of fourteen secondary metabolites in P. cincinnata extracts. These results showed the potentiality of this species as a source of phenolic compounds and antioxidants. 相似文献
86.
One of the objectives of the Intergeo project was to provide European mathematics teachers with ??good quality?? pedagogical material supporting the use of dynamic geometry software in classrooms. With this aim in view, an online repository/platform was developed to gather various dynamic geometry resources, based on the idea of a teachers?? community feeding the repository, (re)using available resources and sharing practices related to the use of dynamic geometry in classrooms. The repository is thus open to contributions of any user who can deposit, browse, download and use resources, which naturally raises the question how to handle the resource quality issue in such an open environment. This paper reports on the way we tackled this issue in the Intergeo project. We first explain what we mean by a ??good quality?? dynamic geometry resource. We then provide a rationale behind the design of a questionnaire, the main tool for resource quality reviews, which are at the core of the quality assessment process implemented in the repository. Several experiments carried out with groups of teachers in order to confront our research-based view of the resource quality with the teachers?? one and to observe teachers?? usages of the quality assessment process are also reported in the paper. The outcomes of these experiments highlight strengths and limitations of the resource quality assessment process. They also tend to show that the idea of involving teachers into the resource quality assessment is a promising way of stimulating the use of dynamic geometry in classrooms, provided that teachers benefit from a support to make the quality process their own. 相似文献
87.
88.
Trimethylene carbonate (TMC) was copolymerized with D ,L ‐lactide (DLLA) or with ε‐caprolactone (CL), and the degradation of melt‐pressed solid copolymer films in phosphate‐buffered saline at pH 7.4 and 37 °C was followed for a period of over two years. The parent homopolymers were used as reference materials. The degradation profile of TMC‐DLLA‐ and TMC‐CL based copolymers was similar and was best described by autocatalyzed bulk hydrolysis, preferentially of ester bonds. The hydrolysis rates varied by two orders of magnitude, depending on polymer composition and physical characteristics under the degradation conditions. TMC‐DLLA copolymers degraded faster than the parent homopolymers. The copolymers lost their tensile strength in less than five months, after which mass loss occurred. Copolymers with 50 or 80 mol‐% of TMC underwent total degradation in eleven months. For TMC‐CL copolymers, a slow and gradual decrease in molecular weight and deterioration of the mechanical performance was observed. These copolymers maintained suitable mechanical properties for seventeen months or longer. Chain scission in the semicrystalline copolymers resulted in an increase in crystallinity. In comparison with the CL homopolymer, the introduction of a small amount of TMC (10 mol‐%) significantly reduced the increase in crystallinity during degradation. Poly(TMC) specimens were dimensionally stable and showed a negligible decrease in molecular weight. A 60% decrease in the initial tensile strength of the polymer samples was observed after two years.
89.
Hugh C. Mcdonald Howard h. weetall Paula Simon Milton M. Takeguchi Gerald Odstrchel 《Applied biochemistry and biotechnology》1978,3(2):151-160
Antiserum specific for propanediol dehydrogenase, an enzyme found inNeisseria gonorrhoeae cells, has been immobilized to glass. When mixed withN gonorrhoeae cell lysates, the immobilized antibody (IMA) binds the enzyme. Over 70% of the calculated adsorbed activity can be recovered from the immobilized antibody-enzyme (IMA-E) complex. When mixed with bacterial lysates prepared from different organisms having propanediol dehydrogenase-like activity, the IMA specifically adsorbed the enzyme from theN gonorrhoeae lysate. IMA-E complexes have been prepared and their kinetic, temperature and chemical stability, and antigenic properties investigated. These studies demonstrated the feasibility of using an immobilized antibody in the detection of the propanediol dehydrogenase enzyme. 相似文献
90.