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101.
Relationships between molecular shape and its crystal packing are studied. The XRD crystal structure of macrocrystals and microcrystals of C6H5HgX, and their VDW packing analysis, suggest two isoenergetic packing models for racket-like molecules. One of them favoring the crystal growth, and the other more frequent forming microcrystalline aggregates. 相似文献
102.
Jos A Hernndez-Díaz Jorge JO Garza-García Janet M Len-Morales Adalberto Zamudio-Ojeda Jenny Arratia-Quijada Gilberto Velzquez-Jurez Julio C Lpez-Velzquez Soledad García-Morales 《Molecules (Basel, Switzerland)》2021,26(19)
The use of selenium nanoparticles (SeNPs) in the biomedical area has been increasing as an alternative to the growing bacterial resistance to antibiotics. In this research, SeNPs were synthesized by green synthesis using ascorbic acid (AsAc) as a reducing agent and methanolic extract of Calendula officinalis L. flowers as a stabilizer. Characterization of SeNPs was performed by UV-vis spectrophotometry, infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques. SeNPs of 40–60 nm and spherical morphologies were obtained. The antibacterial activity of marigold extracts and fractions was evaluated by disk diffusion methodology. The evaluation of SeNPs at different incubation times was performed through the colony-forming unit (CFU) count, in both cases against Serratia marcescens, Enterobacter cloacae, and Alcaligenes faecalis bacteria. Partial antibacterial activity was observed with methanolic extracts of marigold leaves and flowers and total inhibition with SeNPs from 2 h for S. marcescens, 1 h for E. cloacae, and 30 min for A. faecalis. In addition, SeNPs were found to exhibit antioxidant activity. The results indicate that SeNPs present a potentiated effect of both antimicrobial and antioxidant activity compared to the individual use of marigold extracts or sodium selenite (Na2SeO3). Their application emerges as an alternative for the control of clinical pathogens. 相似文献
103.
María Navarro-Cceres Marcelo Caetano Gilberto Bernardes Mercedes Snchez-Barba Javier Merchn Snchez-Jara 《Entropy (Basel, Switzerland)》2020,22(11)
In tonal music, musical tension is strongly associated with musical expression, particularly with expectations and emotions. Most listeners are able to perceive musical tension subjectively, yet musical tension is difficult to be measured objectively, as it is connected with musical parameters such as rhythm, dynamics, melody, harmony, and timbre. Musical tension specifically associated with melodic and harmonic motion is called tonal tension. In this article, we are interested in perceived changes of tonal tension over time for chord progressions, dubbed tonal tension profiles. We propose an objective measure capable of capturing tension profile according to different tonal music parameters, namely, tonal distance, dissonance, voice leading, and hierarchical tension. We performed two experiments to validate the proposed model of tonal tension profile and compared against Lerdahl’s model and MorpheuS across 12 chord progressions. Our results show that the considered four tonal parameters contribute differently to the perception of tonal tension. In our model, their relative importance adopts the following weights, summing to unity: dissonance (0.402), hierarchical tension (0.246), tonal distance (0.202), and voice leading (0.193). The assumption that listeners perceive global changes in tonal tension as prototypical profiles is strongly suggested in our results, which outperform the state-of-the-art models. 相似文献
104.
Among the several types of closures of an ideal I that have been defined and studied in the past decades, the integral closure has a central place being one of the earliest and most relevant. Despite this role, it is often a difficult challenge to
describe it concretely once the generators of I are known. Our aim in this note is to show that in a broad class of ideals their radicals play a fundamental role in testing
for integral closedness, and in case , is still helpful in finding some fresh new elements in . Among the classes of ideals under consideration are: complete intersection ideals of codimension two, generic complete intersection
ideals, and generically Gorenstein ideals.
Received: 28 July 1997 相似文献
105.
We present a hybrid algorithm that combines a genetic algorithm with the Barzilai–Borwein gradient method. Under specific
assumptions the new method guarantees the convergence to a stationary point of a continuously differentiable function, from
any arbitrary initial point. Our preliminary numerical results indicate that the new methodology finds efficiently and frequently
the global minimum, in comparison with the globalized Barzilai–Borwein method and the genetic algorithm of the Toolbox of
Genetic Algorithms of MatLab.
相似文献
106.
Ronie?Cleverson?Cardoso Bruno?Lob?o-SoaresEmail author Marino?Muxfeldt?Bianchin Carlos?Gilberto?CarlottiJr Roger?Walz Márcio?Alvarez-Silva Andréa?Gon?alves?Trentin Mauro?Nicolau 《BMC neuroscience》2004,5(1):38
Background
While it is well known that bradykinin B2 agonists increase plasma protein extravasation (PPE) in brain tumors, the bradykinin B1 agonists tested thus far are unable to produce this effect. Here we examine the effect of the selective B1 agonist bradykinin (BK) Sar-[D-Phe8]des-Arg9BK (SAR), a compound resistant to enzymatic degradation with prolonged activity on PPE in the blood circulation in the C6 rat glioma model.Results
SAR administration significantly enhanced PPE in C6 rat brain glioma compared to saline or BK (p < 0.01). Pre-administration of the bradykinin B1 antagonist [Leu8]-des-Arg (100 nmol/Kg) blocked the SAR-induced PPE in the tumor area.Conclusions
Our data suggest that the B1 receptor modulates PPE in the blood tumor barrier of C6 glioma. A possible role for the use of SAR in the chemotherapy of gliomas deserves further study.107.
Milanesio M Artioli G Gualtieri AF Palin L Lamberti C 《Journal of the American Chemical Society》2003,125(47):14549-14558
The high X-ray flux available at the European Synchrotron Radiation Facility (ESRF), combined with the use of a suitably designed area detector setup, allowed us to follow in real time the structural changes occurring during the template burning processes inside TS-1 and Fe-silicalite MFI zeolites with a X-ray powder diffraction technique (XRPD). Rietveld analysis of the XRPD patterns collected in the 350-1000 K interval, integrated each 15 K, yields to the determination of the template overall occupancy factor versus T with an accuracy comparable with that obtained by thermogravimetric measurements, routinely employed for this purpose. The evolution of the structural parameters (V, a, b, c, site occupancy factor of the template molecule) vs T has been obtained. These data allow us to have, for the first time, a complete view of the structural rearrangements induced by the template burning process on the zeolitic framework. The differences caused by the different heteroatom inserted in the MFI lattice (Ti or Fe) are discussed. For both TS-1 and Fe-MFI, the kinetics of the reaction were investigated, to obtain the activation energy of the calcinations process employing the nonisothermal data according to the theory recently proposed by Kennedy and Clark [Thermochim. Acta, 1997, 307, 27-35]. For TS-1 only, the time-resolved template burning experiment has been repeated in isothermal conditions at four different temperatures, to obtain the activation energy from isothermal data, according to the standard procedure. Comparison between Arrhenius plots obtained from isothermal and nonisothermal data demonstrates that the Kennedy and Clark method can be also applied to complex materials such as the MFI zeolites. This approach, when applied to time-resolved XRPD studies, is much less time consuming (requesting, in principle, one single nonisothermal run) with respect to the classic approach, which requests at least three isothermal runs. Moreover, it allows a remarkably lower associated error (151 +/- 11 versus 146 +/- 30 kJ mol(-)(1)) due to the much higher number of experimental points employed to perform the linear fit. 相似文献
108.
Gilberto Francisco Loibel 《Annali di Matematica Pura ed Applicata》1962,58(1):359-377
Zusammenfassung Die topologischen — Systeme haben durchweg die selben Eingenschaften wie toeologische Gruppeu oder Quasigruppen. In dieser
Arbeit untersuchen wir hauptsaechlich in welchen Punkten Abweichungen in den Resultaten oder Beweismethoden vorhanden sind.
Enrico Bompiani zu seinem wissenschaftlichen Jubil?um 相似文献
109.
Africh C Esch F Li WX Corso M Hammer B Rosei R Comelli G 《Physical review letters》2004,93(12):126104
By means of scanning tunneling microscopy and density functional theory calculations we demonstrate that on the Rh(110)-(10 x 2)-O surface, a prototypical multiphase surface of an oxidized transition metal model catalyst, water formation upon H2 exposure is a two-step reaction, with each step requiring special active sites. The 1st step initiates at (2 x 1)p2mg-O defect islands in the (10 x 2) structure and propagates across the surface as a reaction front, removing half of the adsorbed oxygen. The oxygen decorated Rh ridges of the (10 x 2) structure lose their tensile strain upon this reduction step, whereby nanoscale patches of clean Rh become exposed and act as special reaction sites in the 2nd reaction step, which therefore initiates homogeneously over the entire surface. 相似文献
110.
Alberto Corso Claudia Polini Bernd Ulrich 《Transactions of the American Mathematical Society》2002,354(7):2579-2594
D. Rees and J. Sally defined the core of an -ideal as the intersection of all (minimal) reductions of . However, it is not easy to give an explicit characterization of it in terms of data attached to the ideal. Until recently, the only case in which a closed formula was known is the one of integrally closed ideals in a two-dimensional regular local ring, due to C. Huneke and I. Swanson. The main result of this paper explicitly describes the core of a broad class of ideals with good residual properties in an arbitrary local Cohen-Macaulay ring. We also find sharp bounds on the number of minimal reductions that one needs to intersect to get the core.