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81.
Permutation or randomization test is a nonparametric test in which the null distribution (distribution under the null hypothesis of no relationship or no effect) of the test statistic is attained by calculating the values of the test statistic overall permutations (or by considering a large number of random permutation) of the observed dataset. The power of permutation test evaluated based on the observed dataset is called conditional power. In this paper, the conditional power of permutation tests is reviewed. The use of the conditional power function for sample size estimation is investigated. Moreover, reproducibility and generalizability probabilities are defined. The use of these probabilities for sample size adjustment is shown. Finally, an illustration example is used. 相似文献
82.
83.
Bernardo Lafuerza-Guillén Gaoxun Zhang 《Nonlinear Analysis: Theory, Methods & Applications》2010,73(5):1127-1135
It was shown in Lafuerza-Guillén, Rodríguez-Lallena and Sempi (1999) [8] that uniform boundedness in a Šerstnev PN space (V,ν,τ,τ∗), (named boundedness in the present setting) of a subset A⊂V with respect to the strong topology is equivalent to the fact that the probabilistic radius RA of A is an element of D+. Here we extend the equivalence just mentioned to a larger class of PN spaces, namely those PN spaces that are topological vector spaces (briefly TV spaces), but are not Šerstnev PN spaces.We present a characterization of those PN spaces, whether they are TV spaces or not, in which the equivalence holds. Then, a characterization of the Archimedeanity of triangle functions τ∗ of type τT,L is given. This work is a partial solution to a problem of comparing the concepts of distributional boundedness (D-bounded in short) and that of boundedness in the sense of associated strong topology. 相似文献
84.
Effect of annealing on the properties of N-doped ZnO films deposited by RF magnetron sputtering 总被引:1,自引:0,他引:1
Jinzhong Wang Elangovan Elamurugu François Jomard Ana M. Botelho do Rego Gonçalo Gonçalves Elvira Fortunato 《Applied Surface Science》2008,254(22):7178-7182
N-doped ZnO films were deposited by RF magnetron sputtering in N2/Ar gas mixture and were post-annealed at different temperatures (Ta) ranging from 400 to 800 °C in O2 gas at atmospheric pressure. The as-deposited and post-annealed films were characterized by their structural (XRD), compositional (SIMS, XPS), optical (UV-vis-NIR spectrometry), electrical (Hall measurements), and optoelectronic properties (PL spectra). The XRD results authenticate the improvement of crystallinity following post-annealing. The weak intensity of the (0 0 2) reflection obtained for the as-deposited N-doped ZnO films was increased with the increasing Ta to become the preferred orientation at higher Ta (800 °C). The amount of N-concentration and the chemical states of N element in ZnO films were changed with the Ta, especially above 400 °C. The average visible transmittance (400-800 nm) of the as-deposited films (26%) was increased with the increasing Ta to reach a maximum of 75% at 600 °C but then decreased. In the PL spectra, A0X emission at 3.321 eV was observed for Ta = 400 °C besides the main D0X emission. The intensity of the A0X emission was decreased with the increasing Ta whereas D0X emission became sharper and more optical emission centers were observed when Ta is increased above 400 °C. 相似文献
85.
86.
Joo O. D. Malafatti Marcela P. Bernardo Francys K. V. Moreira Heloisa Ciol Natalia M. Inada Luiz H.C. Mattoso Elaine C. Paris 《先进技术聚合物》2020,31(6):1377-1387
Poly(lactic acid) (PLA) is a versatile, bioabsorbable, and biodegradable polymer with excellent biocompatibility and ability to incorporate a great variety of active agents. Silver sulfadiazine (SDZ) is an antibiotic used to control bacterial infection in external wounds. Aiming to combine the properties of PLA and SDZ, hydrotalcite ([Mg–Al]‐LDH) was used as a host matrix to obtain an antimicrobial system efficient in delivering SDZ from electrospun PLA scaffolds intended for wound skin healing. The structural reconstruction method was successfully applied to intercalate silver sulfadiazine in the [Mg–Al]‐LDH, as evidenced by X‐ray diffraction and thermogravimetric analyses. Observations by scanning electron microscopy revealed a good distribution of SDZ‐[Mg–Al]‐LDH within the PLA scaffold. Kinetics studies revealed a slow release of SDZ from the PLA scaffold due to the intercalation in the [Mg–Al]‐LDH. In vitro antimicrobial tests indicated a significant inhibitory effect of SDZ‐[Mg–Al]‐LDH against Escherichia coli and Staphylococcus aureus. This antibacterial activity was sustained in the 2.5‐wt% SDZ‐[Mg–Al]‐LDH–loaded PLA nanofibers, which also displayed excellent biocompatibility towards human cells. The multifunctionality of the PLA/SDZ‐[Mg–Al]‐LDH scaffold reported here is of great significance for various transdermal applications. 相似文献
87.
88.
Rotem Vardi Marcelino Bernardo Hans Thomann Karl G. Strohmaier David E.W. Vaughan Daniella Goldfarb 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1997,126(2):229-241
X-band (∼9.3 GHz) pulsed ENDOR measurements were carried out on57Fe-substituted sodalite (FeSOD) which contains only one type of Fe(III) (S=) located at a framework site. The ENDOR spectrum recorded atg= 2 shows three doublets corresponding to the sixMSmanifolds. The assignment of these signals was confirmed by hyperfine-selective and triple ENDOR experiments. The components of each of the doublets had different intensities, reflecting the different populations of the EPR energy levels at the measurement temperature, 1.8 K. ENDOR spectra were recorded at magnetic fields within the EPR powder pattern, and the field dependence observed showed an anisotropic behavior, unexpected from the isotropic character of the57Fe(III) hyperfine coupling. This dependence was attributed to the high-order effects of the zero-field splitting (ZFS) interaction on the ENDOR frequencies. Three different theoretical approaches were used to account for the dependence of the ENDOR spectrum on the ZFS interaction. The first involves the exact diagonalization of the total spin Hamiltonian, the second uses third-order perturbation approximations, and the third employs an effective nuclear Hamiltonian for each of theMSmanifolds. The simulations showed that the ENDOR signals of theMS= ±5/2 (ν±5/2) manifold are the least sensitive to the magnitude of the ZFS parameterDand are therefore the most appropriate for the determination ofaiso. It is shown that at X band andaisovalues of about 30 MHz, the perturbation approach is valid up toDvalues of 500 MHz if all three doublets are concerned. However, if only the ν±5/2doublet is considered, then this approach is valid forD< 1000 MHz. The third approach was found inappropriate foraisovalues of ∼30 MHz. Using the method of exact diagonalization together with orientation selectivity, the trends observed in the experimental spectra could be reproduced. The ENDOR spectra of the57Fe-substituted zeolites ZSM5, L, and mazzite showed broad and ill-defined peaks since the ZFS of Fe(III) in these zeolites is significantly larger than that of FeSOD. Because this broadening is a high-order effect, it can be significantly reduced at higher spectrometer frequencies. 相似文献
89.
Pérez Pavón JL Martín SH García Pinto C Moreno Cordero B 《Journal of chromatography. A》2008,1194(1):103-110
A new method based on the use of a headspace autosampler in combination with a GC equipped with a programmable temperature vaporizer (PTV) and an MS detector has been developed for the screening and quantitative determination of trihalomethanes (THMs) in different aqueous matrices. The use of headspace generation to introduce the sample has the advantage that no prior sample treatment is required, thus minimizing the creation of analytical artifacts and the errors associated with this step of the analytical process. The PTV inlet used was packed with Tenax-TA. The injection mode was solvent vent, in which the analytes are retained in the hydrophobic insert packing by cold trapping, while the water vapour is eliminated through the split line. This allows rapid injection of the sample in splitless mode, very low detection limits being achieved without the critical problem of initial sample bandwidth. The capillary column used allowed rapid separations with half-height widths ranging from 1.68 s (chloroform) to 0.66 s (bromoform). The GC run time was 7.3 min. The use of mass spectrometry allows the identification and quantification of the analytes at the low ppt level. The S/N ratio was at least 10-fold higher when the SIM mode was used in data acquisition as compared to the scan mode. The proposed method is extremely sensitive, with detection limits ranging from 0.4 to 2.6 ppt. 相似文献
90.
Berzas Nevado JJ Rodríguez Martín-Doimeadios RC Guzmán Bernardo FJ Jiménez Moreno M 《Analytica chimica acta》2008,621(1):30-37
Laser tomography techniques were used in order to make visible the flow patterns induced by ascending bubbles in flutes poured with champagne. The stability of flow patterns was investigated in flutes showing natural (without any specific surface treatment) as well as artificial effervescence (i.e., engraved at their bottom), all along the first 15 min after pouring. Engravement conditions were found to strongly influence the kinetics and the stability with time of the mixing flow phenomena found in champagne glasses. 相似文献