Iconographie végétale : ou, Organisation des végétaux illustrée au moyen de figures analytiques /

Pritzel (2nd ed.)

Examen d'une chloranthie ou monstruosité observée sur l'inflorescence du saule marceau /

"Extrait des Annales de la Société d'horticulture de Paris, tome xiii, août, 1833."

Flore médicale /

Mode of access: Internet.

Gesta collationis carthagini habitae Honorii Caesaris iussu inter Chatolicos & Donatistas coram Marcellino v.c. Trib. & Not. p.c. Varanis v.c. ... /

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Lettres instructives et curieuses sur l'éducation de la jeunesse; ouvrage utile aux p��res de famille, & nécessaire aux précepteurs, par le R.P.C.M.

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Part I. Kinetics of coarsening of the gamma-prime precipitate in nickel-silicon alloys. Part II. Rate of crystallization of an amorphous Fe-P-C alloy

<p>The coarsening kinetics of Ni₃ Si(γ') precipitate in a binary Ni-Si alloy containing 6.5 wt. % silicon was studied by magnetic techniques and transmission electronmicroscopy. A calibration curve was established to determine the concentration of silicon in the matrix. The variation of the Si content of the Ni-rich matrix as a function of time follows Lifshitz and Wagner theory for diffusion controlled coarsening phenomena. The estimated values of equilibrium solubility of silicon in the matrix represent the true coherent equilibrium solubilities.p> <p>The experimental particle-size distributions and average particle size were determined from dark field electron micrographs. The average particle size varies linearly with tp>-1/3p> as suggested by Lifshitz and Wagner. The experimental distributions of particle sizes differ slightly from the theoretical curve at the early stages of aging, but the agreement is satisfactory at the later stages. The values of diffusion coefficient of silicon, interfacial free energy and activation energy were calculated from the results of coarsening kinetics. The experimental value of effective diffusion coefficient is in satisfactory agreement with the value predicted by the application of irreversible the rmodynamics to the process of volume constrained growth of coherent precipitate during coarsening. The coherent γ' particles in Ni-Sialloy unlike those in Ni-Al and Ni-Ti seem to lose coherency at high temperature. A mechanism for the formation of semi-coherent precipitate is suggested.p>

Carrier transport properties of the (n)nc-Si : H/(p)c-Si heterojunction

Phosphor-doped nano-crystalline silicon ((n))nc-Si:H) films are successfully grown on the p-type (100) oriented crystal silicon ((p) c-Si) substrate by conventional plasma-enhanced chemical vapor deposition method. The films are obtained using high H-2 diluted SiH4 as a reaction gas source and using PH3 as the doping gas source of phosphor atoms. Futhermore, the heterojunction diodes are also fabricated by using (n)nc-Si:H films and (p)c-Si substrate. I-V properties are investigated in the temperature range of 230-420K. The experimental results domenstrate that (n)nc-Si:H/(p) c-Si heterojunction is a typical abrupt heterojunction having good rectifing and temperature properties. Carrier transport mechanisms are tunneling - recombination model at forward bias voltages. In the range of low bias voltages ( V-F< 0.8 V), the current is determined by recombination at the (n)nc-Si:H side of the space charge region, while the current becomes tunneing at higher bias voltages( V-F>1.0 V). The present heterojunction has high reverse breakdown voltage ( > - 75 V) and low reverse current (approximate to nA).

(n)nc-Si:H/(p)c-Si异质结中载流子输运性质的研究

采用常规等离子体增强化学气相沉积工艺，以高H_2稀释的SiH_4作为反应气体源和PH_3作为磷原子的参杂剂，在p���(100)单晶硅C(p)c-Si)衬底上，成功地生长了施主掺杂型纳米硅膜C(n)nc-Si:H),进而制备了(n)nc-Si;H/(p)c-Si异质结，并在230-420K温度范围内实验研究了该异质结的I-V特性。结果表明，(n)nc-Si:H/(p)c-Si异质结为一典型的突变异质结构，具有良好的温度稳定性和整流特性。正向偏压下，该异质结的电流输运机理为复合－隧穿模型。当正向偏压V_F<0.8V时，电流输运过程由复合机理所支配；而当V_F>1.0V时由隧穿机理决定。反向偏压下，该异质结具有良好的反向击穿持性。

Enhancement of the electrooxidation of ethanol on Pt-Sn-P/C catalysts prepared by chemical deposition process

In this paper, five Pt3Sn1/C catalysts have been prepared using three different methods. It was found that phosphorus deposited on the surface of carbon with Pt and Sn when sodium hypophosphite was used as reducing agent by optimization of synthetic conditions such as pH in the synthetic solution and temperature. The deposition of phosphorus should be effective on the size reduction and markedly reduces PtSn nanoparticle size, and raise electrochemical active surface (EAS) area of catalyst and improve the catalytic performance. TEM images show PtSnP nanoparticles are highly dispersed on the carbon surface with average diameters of 2 nm. The optimum composition is Pt3Sn1P2/C (note PtSn/C-3) catalyst in my work. With this composition, it shows very high activity for the electrooxidation of ethanol and exhibit enhanced performance compared with other two Pt3Sn1/C catalysts that prepared using ethylene glycol reduction method (note PtSn/C-EG) and borohydride reduction method (note PtSn/-B). The maximum power densities of direct ethanol fuel cell (DEFC) were 61 mW cm(-2) that is 150 and 170% higher than that of the PtSn/C-EG and PtSn/C-B catalyst.