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991.
ngelo Antnio Barbosa de Moraes Celeste de Jesus Pereira Franco Oberdan Oliveira Ferreira Everton Luiz Pompeu Varela Lidiane Diniz do Nascimento Mrcia Moraes Cascaes Dehon Ricardo Pereira da Silva Sandro Percrio Mozaniel Santana de Oliveira Eloisa Helena de Aguiar Andrade 《Molecules (Basel, Switzerland)》2022,27(17)
The Myrtaceae family is one of the most representative in the Amazon. Several species have high added-value pharmacological potential. In order to contribute to the knowledge of the aromatic profile of Myrtaceae species from the Amazon, the present study presents the first report on the productivity, chemical composition, and antioxidant profile of the essential oil (EO) of Myrcia paivae. Dry leaves of the species were submitted to hydrodistillation to obtain their EO. The EO performance was calculated on a moisture-free basis and the analysis of the chemical profile was carried out by GC/MS. The determination of the antioxidant capacity was assessed by means of the antioxidant capacity equivalent to the inhibition Trolox of the ABTS•+ and DPPH• radicals. The results indicate that EO performance was equivalent to 1.69%. As for the chemical composition, hydrocarbon monoterpenes were predominant in the sample (>77%); terpinolene (14.70%), α-phellandrene (14.69%), γ-terpinene (9.64%), sylvestrene (7.62%), α-thujene (6.46%), and α-pinene (6.39%) were the constituents with higher content. Regarding the antioxidant capacity, the results show that the EO presented good results in the inhibition of ABTS•+ (0.886 ± 0.226 mM L−1) and DPPH• (2.90 ± 0.083 mM L−1), which can be attributed to the high monoterpene content in the sample. 相似文献
992.
Dr. Debabrata Maity Yujeong Oh Dr. Lothar Gremer Prof. Wolfgang Hoyer Prof. Mazin Magzoub Prof. Andrew D. Hamilton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(38):e202200456
Two “hot segments” within an islet amyloid polypeptide are responsible for its self-assembly, which in turn is linked to the decline of β-cells in type 2 diabetes (T2D). A readily available water-soluble, macrocyclic host, cucurbit[7]uril (CB[7]), effectively inhibits islet amyloid polypeptide (IAPP) aggregation through ion–dipole and hydrophobic interactions with different residues of the monomeric peptide in its random-coil conformation. A HSQC NMR study shows that CB[7] likely modulates IAPP self-assembly by interacting with and masking major residues present in the “hot segments” at the N terminus. CB[7] also prevents the formation of toxic oligomers and inhibits seed-catalyzed fibril proliferation. Importantly, CB[7] recovers rat insulinoma cells (RIN-m) from IAPP-assembly associated cytotoxicity. 相似文献
993.
Dean Marković Dr. Chandra M. R. Volla Dr. Pierre Vogel Prof. Dr. Adrián Varela‐Álvarez José A. Sordo Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(20):5969-5975
The first ene reactions of SO2 and unfunctionalized alkenes are reported. Calculations suggest that the endergonic ene reactions of SO2 with alkenes can be used to generate β,γ‐unsaturated sulfinyl and sulfonyl compounds. Indeed, in the presence of one equivalent of BCl3, the unstable sulfinic acid form stable sulfinic acid?BCl3 complexes that can be reacted in situ with NCS to generate corresponding sulfonyl chlorides, or with a base to generate corresponding sulfinates. The latter can be reacted with electrophiles to generate sulfones, or with silyl chloride to form β,γ‐unsaturated silyl sulfinates. The sulfinic acid?BCl3 complexes can be reacted with ethers that act as oxygen nucleophiles to produce corresponding sulfinic esters. Thus one‐pot, three‐component synthesis of β,γ‐unsaturated sulfonamides, sulfinyl esters and sulfones have been developed starting from alkenes and sulfur dioxide (reagent and solvent). 相似文献
994.
Scott J. Tumey Thomas A. Brown Bruce A. Buchholz Terry F. Hamilton Ian D. Hutcheon Ross W. Williams 《Journal of Radioanalytical and Nuclear Chemistry》2009,282(3):721-724
By making modifications to our previously established measurement setup, we increased our abundance sensitivity for 233U by three orders of magnitude and can now measure 233U/238U ratios as low as 10−13. Because 233U has separate production pathways than 236U, it can provide valuable information on the particular source of anthropogenic uranium in a sample. We demonstrated the
utility of our improved capability by using 233U to distinguish separate sources of anthropogenic uranium in a set of samples collected from a contaminated site. In the
future, we plan to apply our new capability to characterizing 233U in a wide range of uranium materials. 相似文献
995.
Mary L. Hamilton John C. Caulfield John A. Pickett Antony M. Hooper 《Tetrahedron letters》2009,50(40):5656-5659
[2′,3′,5′,6′-2H4]-2-Hydroxynaringenin is synthesised and incubated with commercially available UDP-glucose and the crude protein extract from Desmoduim uncinatum leaves. The organic extract produces isotopically labelled [2′,3′,5′,6′-2H4]-vitexin and [2′,3′,5′,6′-2H4]-isovitexin. Repeating the experiment with denatured protein or replacing the 2-hydroxynaringenin with [2′,3′,5′,6′-2H4]-apigenin or [2′,3′,5′,6′-2H4]-naringenin results in no observable incorporation. 2-Hydroxynaringenin is therefore the substrate for C-glucosylflavonoid biosynthesis in D. uncinatum. 相似文献
996.
Collective Band Structures and Identification of One-Phonon and Two-Phonon γ-Vibrational Bands in 109Tc
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GU Long ZHU Sheng-Jiang J. H. Hamilton A. V. Ramayya J. K. Hwang S. H. Liu WANG Jian-Guo Y. X. Luo J. O. Rasmussen I. Y. Lee XU Qiang E. Y. Yeoh W. C. Ma 《中国物理快报》2010,27(6):62-65
The high spin states of the neutron-rich 109Tc nucleus are reinvestigated by observing prompt γ-rays from the spontaneous fission of 252 Cf. The previously known yrast band based on the 7/2+ state is updated. A side band built on the 11/2+ state is expanded and a new band based on the 15/2+ state is identified. Band crossing in the yrast band occurs around fω≈ 0.36 MeV. This band crossing is associated with the alignment of two h11/2 neutrons according to the cranked shell model calculations. The band based on the 11/2+ state is proposed as a candidate for the one-phonon γ-vibrational band, and the band built on the 15/2+ state is proposed as a candidate for the two-phonon γ-vibrational band. Other characteristics for the observed bands are discussed. 相似文献
997.
D. J. Hamilton M. G. D. Nix S. G. Baran G. Hancock A. J. Orr-Ewing 《Applied physics. B, Lasers and optics》2010,100(2):233-242
Optical feedback cavity-enhanced absorption spectroscopy (OF-CEAS) has been demonstrated by coupling a distributed feedback
diode laser to a ring cavity. Frequency-selected light decaying from the ring cavity is retro-reflected, inducing a counter-propagating
intra-cavity beam, and providing optical feedback to the laser. At specific laser-to-cavity distances, all cavity mode frequencies
return to the diode laser with the same phase, allowing spectra to be accumulated across the range of frequencies of the current-tuned
laser. OF-CEAS has been used to measure very weak oxygen isotopologue (16O18O and 16O17O) absorptions in ambient air at wavelengths near 762 nm using the electric-dipole forbidden O2
A-band. A bandwidth reduced minimum detectable absorption coefficient of 2.2×10−9 cm−1 Hz−1/2 is demonstrated. 相似文献
998.
B. Alonso O. Varela I. J. Sola J. San Román A. Za?r C. Méndez L. Roso 《Applied physics. B, Lasers and optics》2010,101(1-2):15-22
The influence of the input pulse chirp and energy on the filamentation process is studied. Output beam profiles, spectra and energies were systematically measured by changing the pulse chirp for different input energies. A map of the different energy-chirp regions was compiled. It shows that high-energy stable single filament can be obtained by using chirped input pulses, allowing the scaling-up of the energy throughput in the filament. Moreover, under high-energy regimes nonlinear effects induced by chirped pulses could produce pulse post-compression. 相似文献
999.
F.V. Motta A.P.A. Marques J.W.M. Espinosa P.S. Pizani E. Longo J.A. Varela 《Current Applied Physics》2010,10(1):16-20
It was used the Complex Polymerization Method to synthesize barium calcium titanate powders (BCT). Crystalline Ba0.8Ca0.2TiO3 perovskite-type phase could be identified by X-ray diffraction and confirmed by Raman spectroscopy in the powders heat treated at 600 °C. Inherent defects, linked to structural disorder, facilitate the photoluminescence emission. The photoluminescent emission peak maximum was around of 533 nm (2.33 eV) for the Ba0.8Ca0.2TiO3. The photoluminescence process and the band emission energy photon showed dependence of both the structural order–disorder and the thermal treatment history. The results revealed that Ba0.8Ca0.2TiO3 (BCT20) is a highly promising candidate material for optical applications. 相似文献
1000.
In this paper we develop a methodology for defining stopping rules in a general class of global random search algorithms that
are based on the use of statistical procedures. To build these stopping rules we reach a compromise between the expected increase
in precision of the statistical procedures and the expected waiting time for this increase in precision to occur. 相似文献