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81.
PLD-assisted VLS growth of aligned ferrite nanorods, nanowires, and nanobelts-synthesis, and properties 总被引:4,自引:0,他引:4
Morber JR Ding Y Haluska MS Li Y Liu JP Wang ZL Snyder RL 《The journal of physical chemistry. B》2006,110(43):21672-21679
We report here a systematic synthesis and characterization of aligned alpha-Fe2O3 (hematite), epsilon-Fe2O3, and Fe3O4 (magnetite) nanorods, nanobelts, and nanowires on alumina substrates using a pulsed laser deposition (PLD) method. The presence of spherical gold catalyst particles at the tips of the nanostructures indicates selective growth via the vapor-liquid-solid (VLS) mechanism. Through a series of experiments, we have produced a primitive "phase diagram" for growing these structures based on several designed pressure and temperature parameters. Transmission electron microscopy (TEM) analysis has shown that the rods, wires, and belts are single-crystalline and grow along <111>m or <110>h directions. X-ray diffraction (XRD) measurements confirm phase and structural analysis. Superconducting quantum interference device (SQUID) measurements show that the iron oxide structures exhibit interesting magnetic behavior, particularly at room temperature. This work is the first known report of magnetite 1D nanostructure growth via the vapor-liquid-solid (VLS) mechanism without using a template, as well as the first known synthesis of long epsilon-Fe2O3 nanobelts and nanowires. 相似文献
82.
Nuvoli Daniele Alzari Valeria Sanna Roberta Scognamillo Sergio Alongi Jenny Malucelli Giulio Mariani Alberto 《Journal of nanoparticle research》2013,15(3):1-8
In this paper, GaN nanoparticles were synthesized from the complex Ga(H2NCONH2)6Cl3 in the flow of NH3 at a mild temperature (350 °C). Further purification was performed by the ethanol-thermal method. The ethanol-thermal method also prompted the GaN nanoparticles to grow into an anisotropic morphology. XRD patterns reveal that GaN nanoparticles have crystallized in a hexagonal wurtzite structure. TEM observation shows that the average size of the as-prepared nanoparticles is about 5–10 nm. The photoluminescence spectrum exhibits a broad green emission band with a peak at 510 nm. It can be known from the first-principle theoretic simulation by the TDDFT method that this fluorescence emission band is attributed to the hydride defects of V N-H on the surface of GaN nanoparticles. 相似文献
83.
Johan Sundberg Thomas F. Cleveland R.E. Stone Jr. Jenny Iwarsson 《Journal of voice》1999,13(2):168-183
Voice source characteristics as derived from inverse filtering were analyzed in 6 country singers' speech and singing. Results showed that the closed quotient varied systematically with vocal loudness, and that glottal compliance (the ratio between transglottal AC volume displacement and subglottal pressure) decreased with increases in fundamental frequency but remained unaffected by vocal loudness. No striking differences were found in source characteristics between speech and singing within subjects. The degree of phonatory press, as judged by a panel of 19 expert listeners, appeared related to the range in which the singer was singing and to the sound pressure level gain from a doubling of subglottal pressure. 相似文献
84.
Tolga Kaya Gengchen Liu Jenny Ho Kumar Yelamarthi Kevin Miller Jeffrey Edwards Alicja Stannard 《Electroanalysis》2019,31(3):411-421
Sweat‐related physiology research has been well established over the years. However, it has only been around ten years that sweat‐based sensing devices started to be explored. With the recent advancements in wearable activity and physiology monitoring devices, sweat was investigated for its contents similar to blood and corresponding wearable devices were studied intensively. This article provides a thorough review on sweating mechanisms, sweat sensing devices, and electronic technologies for sweat sensor implementations. Potential future directions and recommendations based on current research trends were provided in each section. This review aims to offer a unique perspective from both physiology and engineering point‐of‐view to draw a complete landscape of the sweat sensing research. 相似文献
85.
Jenny Halleröd Chrisitan Ekberg Ivan Kajan Emma Aneheim 《Journal of solution chemistry》2018,47(6):1021-1036
The two organic ligands 6,6′-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydrobenzo[1,2,4]triazin-3-yl)[2,2′]bipyridine (CyMe\(_{4}\)-BTBP) and tri-butyl phosphate (TBP) have previously been investigated in different diluents for use within recycling of used nuclear fuel through solvent extraction. The thermodynamic parameters, \(K_{\mathrm{S}}\), \(\Delta C_{p}\), \(\Delta H^{0}\) and \(\Delta S^{0}\), of the CyMe\(_{4}\)-BTBP solubility in three diluents (cyclohexanone, octanol and phenyl trifluoromethyl sulfone) mixed with TBP have been studied at 288, 298 and 308 K, both as pristine solutions and pre-equilibrated with 4 mol\(\cdot \)L\(^{-1}\) nitric acid. In addition, the amount of acid in the organic phase and density change after pre-equilibration have been measured. The solubility of CyMe\(_{4}\)-BTBP increases with an increased temperature in all systems, especially after acid pre-equilibration. This increased CyMe\(_{4}\)-BTBP solubility after pre-equilibration could be explained by acid dissolution into the solvent. Comparing the \(\Delta H^{0}\) and \(\Delta S^{0}\) calculated using \(\Delta C_{p}\) with the same parameters derived from a linear fit indicates temperature independence of all three thermodynamic systems. The change in enthalpy is positive in all solutions. 相似文献
86.
A de novo intramolecular hydroamination of conjugated enynes was developed using commercially available n-BuLi as a precatalyst. This hydroamination reaction successfully afforded allenyl-substituted pyrrolidines with up to 95% yield. One of the resulting allenyl pyrrolidines was converted to the natural products irniine and irnidine in three steps. 相似文献
87.
Janey JM Orella CJ Njolito E Baxter JM Rosen JD Palucki M Sidler RR Li W Kowal JJ Davies IW 《The Journal of organic chemistry》2008,73(8):3212-3217
An expedient, five step synthesis of caprolactam 1 is reported starting from natural L-homoserine. The key step is a chemoselective reductive cyclization of alpha,beta-unsaturated nitrile 10 mediated by Raney-Co type metals. This hydrogenation is extensively investigated in order to account for the observed product distribution and yields. 相似文献
88.
89.
90.
Amouri H Waern JB Caspar R Barbieri A Sabatini C Zanelli A Barigelletti F 《Dalton transactions (Cambridge, England : 2003)》2007,(21):2179-2186
The first trans-ruthenium complex trans-[Ru(DIP)2(MeOH)2][OTf]2 (1b, where DIP = 4,7-diphenyl-1,10-phenanthroline) incorporating a pi-extended ligand was prepared via two methods: either photolysis of cis-[Ru(DIP)2(OTf)2] in MeOH-Et(2)O or via crystallization from MeOH-Et(2)O in direct sunlight. The X-ray molecular structure of is reported and confirmed the trans geometry of the title compound. The cis-trans isomerization process was monitored by 1H-NMR and showed that 1b reverts back to cis-[Ru(DIP)2(MeOH)2][OTf]2 (1a) in methanol-d4 after 15 h at 55 degrees C or several days at room temperature. The absorption spectra recorded in MeOH showed a bathochromic shift of the MLCT band of the trans-isomer 1b relative to that of the cis complex 1a. Interestingly at 77 K the emission spectrum of 1b is red shifted compared to the cis analog 1a. A rational explanation in terms of the energy of the excited states in the cis- and trans-isomers is proposed to explain this behavior. 相似文献