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841.
Alexandra-Elisabeta Stamate Rodica Zvoianu Octavian Dumitru Pavel Ruxandra Birjega Andreea Matei Marius Dumitru Ioana Brezetean Mariana Osiac Ioan-Cezar Marcu 《Molecules (Basel, Switzerland)》2021,26(20)
Mechanical activation and mechanochemical reactions are the subjects of mechanochemistry, a special branch of chemistry studied intensively since the 19th century. Herein, we comparably describe two synthesis methods used to obtain the following layered double hydroxide doped with cerium, Mg3Al0.75Ce0.25(OH)8(CO3)0.5·2H2O: the mechanochemical route and the co-precipitation method, respectively. The influence of the preparation method on the physico-chemical properties as determined by multiple techniques such as XRD, SEM, EDS, XPS, DRIFT, RAMAN, DR-UV-VIS, basicity, acidity, real/bulk densities, and BET measurements was also analyzed. The obtained samples, abbreviated HTCe-PP (prepared by co-precipitation) and HTCe-MC (prepared by mechanochemical method), and their corresponding mixed oxides, Ce-PP (resulting from HTCe-PP) and Ce-MC (resulting from HTCe-MC), were used as base catalysts in the self-condensation reaction of cyclohexanone and two Claisen–Schmidt condensations, which involve the reaction between an aromatic aldehyde and a ketone, at different molar ratios to synthesize compounds with significant biologic activity from the flavonoid family, namely chalcone (1,3-diphenyl-2-propen-1-one) and flavone (2-phenyl-4H-1benzoxiran-4-one). The mechanochemical route was shown to have indisputable advantages over the co-precipitation method for both the catalytic activity of the solids and the costs. 相似文献
842.
843.
Luis M. Carrillo-Lopez Bianka Y. Cruz-Garibaldi Mariana Huerta-Jimenez Ivan A. Garcia-Galicia Alma D. Alarcon-Rojo 《Molecules (Basel, Switzerland)》2022,27(2)
The effect of high-intensity ultrasound (HIU) system (bath, 37 kHz and 90 W/cm2; or probe, 24 kHz and 400 W) and application time (25 or 50 min, one-side exposition) on the properties of bovine Longissimus lumborum after 7 d of storage at 4 °C was studied. The bath system significantly increased the lightness of the muscle, while other color parameters (a*, b*, hue, and chroma) were not different from the control. The water holding capacity and shear force decreased significantly (3.1–5% and 0.59–0.72 kgf, respectively) in sonicated meat independently of the system, favoring the tenderization of the muscle after storage. Microstructural changes observed in the HIU-exposed surface provided evidence of a higher area of interfibrillar spaces (1813 vs. 705 µm2 in the control), producing tenderization of the muscle, compared with the control. HIU significantly increased counts of total aerobic and coliform bacteria, especially after 50 min of ultrasonication. HIU also increased lactic acid bacterial counts in the bath system. Single-sided muscle exposition to ultrasound may produce sufficient significant changes in muscle properties, which could decrease long treatment times that would be needed for the exposition of both sides. HIU in bath systems increases tenderness by modifying meat ultrastructure, with no significant changes in physicochemical parameters. Nevertheless, microbiological quality may need to be considered during the process due to a slight increase in bacterial counts. 相似文献
844.
J. Mrázek M. Honusek A. Špalek J. Bielčík J. Slívová J. Adam A.A. Pasternak 《The European Physical Journal A - Hadrons and Nuclei》1999,5(4):399-408
The results of in-beam investigations of excited states of 99Ru using the 98Mo(α,3n) reaction are presented. Angular distributions of γ–rays and γ–γ coincidences have been measured. Excited states have
been identified up to an energy of E = 5603 keV and spin of Iπ= 31/2−. Mean lifetimes τ have been determined using the DSA method for eleven levels. Aligned angular momenta are discussed and
the probable (νh
11/2) origin of a backbending at frequency about 0.5 MeV was confirmed. The possible role of (νd
5/2) alignment at frequencies above 0.5 MeV was pointed out.
Received: 13 January 1999 / Revised version: 26 March 1999 相似文献
845.
利用ΔE-E望远镜系统测量了156.3MeV 28Si+12C反应(近对称系统)中出射的Z=4—14的产物元素的能谱和角分布,并由此给出了这些产物的胁变截面图.从理论上计算了Z=4—11产物的实验室系最可几动能分布E1(θ)和各元素的质心系的总动能分布Et(Z),指出了这些产物主要来自系统的两体反应过程.还给出了该反应系统的全熔合截面值为(980±68)mb,并指出从低能数据外推到此能量下的全熔合截面值与实验值之差主要归因于两体过程. 相似文献
846.
Mariana Grana 《International Journal of Theoretical Physics》1999,38(4):1359-1371
We formulate a phenomenological model where theinflaton fluctuations are treated as a fluid. Byapplying the hydrodynamic equations to this fluid werecover the conventional result that relates thespectrum of density fluctuations in the inflaton fieldat reentering the horizon to the spectrum offluctuations at the time a scale leaves the horizon.Moreover, through the equivalent viscosity of the fluidwe obtain a Reynolds number that suggeststurbulent motion, which implies that mode–modecoupling in the inflaton field cannot be neglected. Forde Sitter inflation the resulting spectrum usingturbulence theory is scale invariant on all scales ofinterest. This suggests that the hypothesis of anextremely weakly coupled inflation could be relaxedwithout affecting the predictions of themodel. 相似文献
847.
Mariana Stoica Monica Caldararu N. I. Ionescu 《Reaction Kinetics and Catalysis Letters》1999,66(2):387-392
Hydrogen desorption, hydrogen spillover and reduction processes have been evidenced using a new experimental strategy based
on AC electric conductivity measurements during TPD and TPR experiments on a 0.5% Pt/Al2O3 catalyst. 相似文献
848.
Temitope T. Abiola Benjamin Rioux Josene M. Toldo Jimmy Alarcan Jack M. Woolley Matthew A. P. Turner Daniel J. L. Coxon Mariana Telles do Casal Cdric Peyrot Matthieu M. Mention Wybren J. Buma Michael N. R. Ashfold Albert Braeuning Mario Barbatti Vasilios G. Stavros Florent Allais 《Chemical science》2021,12(46):15239
Light-to-heat conversion materials generate great interest due to their widespread applications, notable exemplars being solar energy harvesting and photoprotection. Another more recently identified potential application for such materials is in molecular heaters for agriculture, whose function is to protect crops from extreme cold weather and extend both the growing season and the geographic areas capable of supporting growth, all of which could help reduce food security challenges. To address this demand, a new series of phenolic-based barbituric absorbers of ultraviolet (UV) radiation has been designed and synthesised in a sustainable manner. The photophysics of these molecules has been studied in solution using femtosecond transient electronic and vibrational absorption spectroscopies, allied with computational simulations and their potential toxicity assessed by in silico studies. Following photoexcitation to the lowest singlet excited state, these barbituric absorbers repopulate the electronic ground state with high fidelity on an ultrafast time scale (within a few picoseconds). The energy relaxation pathway includes a twisted intramolecular charge-transfer state as the system evolves out of the Franck–Condon region, internal conversion to the ground electronic state, and subsequent vibrational cooling. These barbituric absorbers display promising light-to-heat conversion capabilities, are predicted to be non-toxic, and demand further study within neighbouring application-based fields.The synthesis and photophysical properties of phenolic barbiturics are reported. These molecules convert absorbed ultraviolet light to heat with high fidelity and may be suitable for inclusion in foliar sprays to boost crop protection and production. 相似文献
849.
Georgiana Ioana Potra Cicalu Petru Aurel Babes Horia Calniceanu Adelina Popa Gabriela Ciavoi Gilda Mihaela Iova Mariana Ganea Ioana Scrobot 《Molecules (Basel, Switzerland)》2021,26(22)
Periodontal disease and diabetes mellitus are two pathologies that are extremely widespread worldwide and share the feature of chronic inflammation. Carvacrol is a phenolic monoterpenoid, produced by a variety of herbs, the most well-known of which is Origanum vulgare. Magnolol is a traditional polyphenolic compound isolated from the stem bark of Magnolia officinalis, mainly used in Chinese medicine. The purpose of this paper is to review the therapeutic properties of these bioactive compounds, in the treatment of periodontitis and diabetes. Based on our search strategy we conducted a literature search in the PubMed and Google Scholar databases to identify studies. A total of one hundred eighty-four papers were included in the current review. The results show that carvacrol and magnolol have anti-inflammatory, antioxidant, antimicrobial, anti-osteoclastic, and anti-diabetic properties that benefit both pathologies. Knowledge of the multiple activities of carvacrol and magnolol can assist with the development of new treatment strategies, and the design of clinical animal and human trials will maximize the potential benefits of these extracts in subjects suffering from periodontitis or diabetes. 相似文献
850.
Andrea Angeli Victor Kartsev Anthi Petrou Mariana Pinteala Volodymyr Brovarets Roman Vydzhak Svitlana Panchishin Athina Geronikaki Claudiu T. Supuran 《Molecules (Basel, Switzerland)》2021,26(22)
A series of benzenesulfonamides incorporating pyrazole- and pyridazinecarboxamides decorated with several bulky moieties has been obtained by original procedures. The new derivatives were investigated for the inhibition of four physiologically crucial human carbonic anhydrase (hCA, EC 4.2.2.1.1) isoforms, hCA I and II (cytosolic enzymes) as well as hCA IX and XII (transmembrane, tumor-associated isoforms). Examples of isoform-selective inhibitors were obtained for all four enzymes investigated here, and a computational approach was employed for explaining the observed selectivity, which may be useful in drug design approaches for obtaining inhibitors with pharmacological applications useful as antiglaucoma, diuretic, antitumor or anti-cerebral ischemia drugs. 相似文献