We present an ensemble tree-based algorithm for variable selection in high-dimensional datasets, in settings where a time-to-event outcome is observed with error. This work is motivated by self-reported outcomes collected in large-scale epidemiologic studies, such as the Women’s Health Initiative. The proposed methods equally apply to imperfect outcomes that arise in other settings such as data extracted from electronic medical records. To evaluate the performance of our proposed algorithm, we present results from simulation studies, considering both continuous and categorical covariates. We illustrate this approach to discover single nucleotide polymorphisms that are associated with incident Type 2 diabetes in the Women’s Health Initiative. A freely available R package icRSF has been developed to implement the proposed methods. Supplementary material for this article is available online. 相似文献
Nonlinear Dynamics - A new model-free robust control scheme for payload swing angle attenuation of two-dimensional crane systems with varying rope length is introduced in this work. The proposed... 相似文献
Application of our recently reported metal free reaction conditions to the total synthesis of the four different and selective biologically interesting β-carboline natural products is reported. Using this simple methodology, flazin, perlolyrine, eudistomin U and harmane containing heteroaryl and alkyl substituents at C1 position were synthesized in good yields.
Bimetallic Co–Ni catalysts in the composition range Co(1?x)Nix with x?=?0.0, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8 and 1.0, with total metal loading of 15% w/w and supported on TiO2-P25, have been prepared by chemical reduction of the metal acetates by glucose in aqueous alkaline medium and characterized by XRD, TEM, TPR, XPS and H2-TPD techniques. Selective hydrogenation of cinnamaldhyde (CAL) to hydrocinnamaldehyde (HCAL), cinnamyl alcohol (COL) and hydrocinnamyl alcohol (HCOL) has been investigated at 20 bar pressure, in the temperature range 120–140 °C. Co/Ni crystallite sizes in the range 6.0?±?1 nm are observed by TEM. TPR and XPS results indicate the formation of nanoscale Co–Ni alloys, which tend to weaken M–H bond strength, as revealed by H2-TPD measurements. Ni/TiO2 displays very high conversion of CAL (86.9%) with high selectivity (78.7%) towards HCAL formation at 140 °C. Co/TiO2, on the other hand, exhibits relatively lower CAL conversion (55%) and higher selectivity (61.3%) for COL formation at the same temperature. However, bi-metallic Co–Ni catalysts in the composition range x?=?0.3–0.6 display very high conversion (>?98%) due to alloy formation and weakening of M–H bonds. Bimetallic Co0.7Ni0.3 catalyst displays high conversion of CAL (98.1%) and high selectivity (82.9%) towards HCOL. Overall CAL hydrogenation activity at 140 °C, when expressed as TOF, displays a maximum value at the composition Co0.5Ni0.5. Activity and selectivity patterns have been rationalized based on the reaction pathways observed on the catalysts and the influence of Co–Ni alloy formation and M–H bond strength. Thus, a synergetic effect, originating from an appropriate composition of base metal catalysts and reaction conditions, could result in hydrogenation activity comparable with noble metal based catalysts. 相似文献
A voltammetric sensor is described for the determination the antibiotic sulfamethoxazole (SMZ). It is based on the use of a glassy carbon electrode (GCE) modified with a nanocomposite prepared from graphitic carbon nitride and zinc oxide (g-C3N4/ZnO). The nanorod-like ZnO nanostructure were synthesized sonochemically. The g-C3N4/ZnO nanocomposite was then prepared by mixing g-C3N4 with ZnO, followed by ultrasonication. The morphology and structure of the nanocomposite were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy and transmission electron microscopy. Under the optimal conditions, the response of the electrode, typically measured between 0.8 and 0.9 V (vs. Ag/AgCl), increases linearly in the 20 nM to 1.1 mM SMZ concentration range, and the lower detection limit is 6.6 nM. This is better than that of many previously reported sensors for SMZ. The modified electrode is highly selective, well reproducible and maintains its activity for at least 4 weeks. It was applied to the determination of SMZ in spiked human blood serum samples in with satisfactory results.
Graphical abstract Schematic presentation of the voltammetric sensor for sulfamethoxazole. It consists of a glassy carbon electrode modified with a nanocomposite prepared from graphitic carbon nitride (g-C3N4/ZnO) that was supported with zinc oxide nanorods.
Titanium oxide thin films have been deposited by an ion plating technique under rf glow. The structure of the deposited film has been found to be amorphous and the composition has been analysed by IR spectrum. Aging and annealing studies of the titanium oxide capacitors have been made. The dielectric constant of the film at 1 kHz has been estimated to be 12.4. The dependence of the capacitance and dielectric loss on frequency and temperature have been studied, and the results are discussed. The temperature coefficient of the capacitance has also been calculated. 相似文献
Variously substituted 2,6-diarylpiperidin-4-one O-benzyloximes were synthesized by the direct condensation of the corresponding 2,6-diarylpiperidin-4-ones with O-benzylhydroxylamine hydrochloride. All the synthesized compounds are characterized by IR, Mass and NMR spectral studies. NMR spectral assignments are made unambiguously by their one-dimensional (1H NMR and 13C NMR) and two-dimensional (1H-1H COSY, NOESY, HSQC and HMBC) NMR spectra. All the synthesized compounds are resulted as single isomer, i.e., exclusively E isomer (9-14). The conformational preference of 2,6-diarylpiperidin-4-one oxime ethers with and without alkyl substituents at C-3 and C-5 has also been discussed using the spectral studies. The observed chemical shifts and coupling constants suggest that compounds 8-13 adopt normal chair conformation with equatorial orientation of all the substituents while compound 14 contributes significant boat conformation along with the predominant chair conformation in solution. The effect of oximination on ring carbons, their associated protons, alkyl substituents and ipso carbons are studied. Every proton in the piperidone ring of the oxime ether is observed as distinct signal due to oximination. The order of chemical shift magnitude in compound 8 is H-2a>H-6a>H-5e>H-3e>H-3a>H-5a. For 9-12, the order is H-6a>H-5e>H-2a>H-3a>H-5a, for 13, H-6a>H-2a>H-5e>H-3a>H-5a and for 14, the order is H-2a>H-6a>H-5e>H-3a>H-5a while the 13C chemical shift magnitude for 8-14 due to oximination is C-2>C-6>C-3>C-5. 相似文献
The synthesis and characterization of Ru(II) terpyridine complexes derived from 4'-functionalized 2,2':6',2'-terpyridine ligands by a multi step procedure have been described. The complexes are redox-active, showing both metal-centred (oxidation) and ligand-centred (reduction) processes. The antibacterial and antifungal activity of the synthesized ruthenium(II) complexes [Ru(attpy)2](PF6)2 (attpy = 4'-(4-acryloyloxymethylphenyl)-2,2':6',2'-terpyridine); [Ru(mttpy)2](PF6)2 (mttpy = 4'-(4-methacryloyloxymethylphenyl)-2,2':6',2'- terpyridine); [Ru(mttpy)(MeOPhttpy)](PF6)2 (MeOPhttpy = 4'-(4-methoxyphenyl)-2,2':6',2'-terpyridine); and [Ru(mttpy)(ttpy)](PF6)2 (ttpy = 4'-(4-methylphenyl)-2,2':6',2'-terpyridine) were tested against four human pathogens (Proteus vulgaris, Proteus mirabilis, Pseudomonas aeruginosa and Escherichia coli) and five plant pathogens (Curvularia lunata, Fusarium oxysporum, Fusarium udum, Macrophomina phaseolina and Rhizoctonia solani) by the well diffusion method and MIC values of the complexes are reported. A biological study of the complexes indicated that the complexes [Ru(mttpy)2](PF6)2 and [Ru(mttpy)(MeOPhttpy)](PF6)2 exhibit very good activity against most of the test pathogens and their activity is better than those of some of the commercially available antibiotics like tetracycline and the fungicide carbendazim. 相似文献
The reaction of (S)P[N(CH(3))N[double bond, length as m-dash]CH-C(6)H(3)-2-OH-3-OCH(3)](3) with a Mn(II) salt followed by a Ln(III) salt (Ln = Eu, Gd and Dy), afforded linear heterometallic complexes [L(2)Mn(2)Ln](+) that showed interesting magnetic properties. 相似文献