5,166 research outputs found
De la memoria de los conservadores-restauradores contemporáneos a la "magdalena" de Marcel Proust. Conversaciones con Juan Carlos Pérez Ferrer y Jesús Serrano Rodríguez
No full textEn el año 2013 el Premio Nacional de Restauración se otorgó a Juan Carlos Pérez Ferrer y Jesús Serrano Rodríguez, por el proyecto de intervención en el Oratorio de San Felipe Neri, en Cádiz. El Grupo Español del IIC celebró el reconocimiento con una entrevista, que aspira a ser un documento de la memoria de los conservadores-restauradores españoles contemporáneos
Ge1-ySny (y=0.01-0.10) alloys on Ge-buffered Si: Synthesis, microstructure, and optical properties
No full textabstract: Novel hydride chemistries are employed to deposit light-emitting Ge [subscript 1- y] Sn [subscript y] alloys with y ≤ 0.1 by Ultra-High Vacuum Chemical Vapor Deposition (UHV-CVD) on Ge-buffered Si wafers. The properties of the resultant materials are systematically compared with similar alloys grown directly on Si wafers. The fundamental difference between the two systems is a fivefold (and higher) decrease in lattice mismatch between film and virtual substrate, allowing direct integration of bulk-like crystals with planar surfaces and relatively low dislocation densities. For y ≤ 0.06, the CVD precursors used were digermane Ge [subscript 2]H[subscript 6] and deuterated stannane SnD[subscript 4]. For y ≥ 0.06, the Ge precursor was changed to trigermane Ge [subscript 3]H[subscript 8], whose higher reactivity enabled the fabrication of supersaturated samples with the target film parameters. In all cases, the Ge wafers were produced using tetragermane Ge [subscript 4]H[subscript 10] as the Ge source. The photoluminescence intensity from Ge [subscript 1− y] Sn [subscript y] /Ge films is expected to increase relative to Ge [subscript 1− y] Sn [subscript y] /Si due to the less defected interface with the virtual substrate. However, while Ge [subscript 1− y] Sn [subscript y] /Si films are largely relaxed, a significant amount of compressive strain may be present in the Ge [subscript 1− y] Sn [subscript y] /Ge case. This compressive strain can reduce the emission intensity by increasing the separation between the direct and indirect edges. In this context, it is shown here that the proposed CVD approach to Ge [subscript 1− y] Sn [subscript y] /Ge makes it possible to approach film thicknesses of about 1 μm, for which the strain is mostly relaxed and the photoluminescence intensity increases by one order of magnitude relative to Ge [subscript 1− y] Sn [subscript y] /Si films. The observed strain relaxation is shown to be consistent with predictions from strain-relaxation models first developed for the Si[subscript 1− x] Ge [subscript x] /Si system. The defect structure and atomic distributions in the films are studied in detail using advanced electron-microscopy techniques, including aberration corrected STEM imaging and EELS mapping of the average diamond–cubic lattice.Copyright 2014 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. along with the following message: The following article appeared in 116, 13 (2014) and may be found at http://dx.doi.org/10.1063/1.489678
Atomic layer deposition of crystalline SrHfO3 directly on Ge (001) for high-k dielectric applications
No full textabstract: The current work explores the crystalline perovskite oxide, strontium hafnate, as a potential high-k gate dielectric for Ge-based transistors. SrHfO3 (SHO) is grown directly on Ge by atomic layer deposition and becomes crystalline with epitaxial registry after post-deposition vacuum annealing at ∼700 °C for 5 min. The 2 × 1 reconstructed, clean Ge (001) surface is a necessary template to achieve crystalline films upon annealing. The SHO films exhibit excellent crystallinity, as shown by x-ray diffraction and transmission electron microscopy. The SHO films have favorable electronic properties for consideration as a high-k gate dielectric on Ge, with satisfactory band offsets (>2 eV), low leakage current (<10[superscript −5] A/cm[superscript 2] at an applied field of 1 MV/cm) at an equivalent oxide thickness of 1 nm, and a reasonable dielectric constant (k ∼ 18). The interface trap density (Dit ) is estimated to be as low as ∼2 × 10[superscript 12] cm[superscript −2] eV[superscript −1] under the current growth and anneal conditions. Some interfacial reaction is observed between SHO and Ge at temperatures above ∼650 °C, which may contribute to increased Dit value. This study confirms the potential for crystalline oxides grown directly on Ge by atomic layer deposition for advanced electronic applications.Copyright 2015 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. along with the following message: The following article appeared in JOURNAL OF APPLIED PHYSICS 117, 5 (2015) and may be found at http://dx.doi.org/10.1063/1.490695
Design and optimization of electrochemical microreactors for continuous electrosynthesis
No full textThe study focuses on the design and construction, as well as the theoretical and experimental optimization of electrochemical filter press microreactors for the electrosynthesis of molecules with a high added value. The main characteristics of these devices are firstly a high-specific electrochemical area to increase conversion and selectivity, and secondly the shape and size of themicrochannels designed for a uniform residence time distribution of the fluid. A heat exchanger is integrated into the microstructured electrode to rapidly remove (or supply) the heat required in exo- or endothermic reactions. The microreactors designed are used to perform-specific electrosynthesis reactions such as thermodynamically unfavorable reactions (continuous NADH regeneration), or reactions with high enthalpy changes
OB00040 - Damodarpur Copper Plate 1 (GE 163) of Budhagupta
No full textDamodarpur Copper Plate 1 (GE 163) of Budhagupt
La red urbana de Murcia / José María Serrano Martínez.
No full textResumen de Tesis - Universidad de Murcia.LUIS VIVES. SALA. 711 SER red.Consulte la tesis en: BCA. GENERAL. DEPOSITO. DPT 68 546.Consulte la tesis en: BCA. GENERAL. DEPOSITO. DPT 68 259.Consulte la tesis en: BCA. GENERAL. DEPOSITO. DPT 109 636.NEBRIJA. DEPOSITO. 11729.NEBRIJA. DEPOSITO. 46930.NEBRIJA. DEPOSITO. 73826.NEBRIJA. DEPOSITO. 73833.NEBRIJA. 1ª CENTRO VESTIBULO. GE.33.375 SER red
Macrocheilus schuelei Serrano 2023, n. sp.
No full text<i>Macrocheilus schuelei</i> n. sp. <p>Figs. 1d, 2d, 3c, 4c</p> <p> <b>Type material.</b> Holotype male: “ RCA, P.N. Ndoki, Camp 1, Chablis 1,\ 02º 28′ 40.5N 016º 13′ 02.6E, 24–25.II.\ 2012 forêt diversifiée, piège UV. Exp.\ Sangha 12, P. Moretto leg. -117-“ \\ “ Collection P. Sch ̧le, Herrenberg\ Shanga Projekt 2012” \\ “Holotype male\ A. Serrano det. 2022” [t] [h] [red card]. Paratype: 1 female: “ RCA, P.N. Ndoki, Camp 1, Chablis 1,\ 02º 28′ 40.5N 016º 13′ 02.6E, 20–\ 23.II.2012 forêt diversifiée, piège UV.\ Exp. Sangha 12, P. Moretto leg. -105-“ \\ “Macr-01” (yellow label) (PSHC) \\ “Paratype female\ A. Serrano det. 2022” [t] [h] [red card]. Holotype deposited in PSC. Paratype deposited in ASC.</p> <p> <b>Differential diagnosis.</b> Slender. Head, pronotum, elytrae and abdomen fuscous black or dark brown; labrum, mouthparts, antennae and legs brown; first half of each elytrum with a large longitudinal orange band; shiny, without microreticulation, pubescent.</p> <p> <b>Description.</b> Length of holotype: 7.0 mm. Length of paratype: 7.4 mm (female).</p> <p> <i>Head</i> (Fig. 1d). Much wider than long (male: length 1.18 mm, width: 1.86 mm; female: length 1.28 mm; width: 1.92 mm). Surface shining, coarsely and deeply punctured, less dense in middle of the frons, each puncture with a long, decumbent and fine brown-yellowish seta, without microsculpture; antero-lateral impressions not marked,</p> <p>ons not excavated behind clypeus; last maxillary palpomere slightly securiform, pubescent; eyes strongly prominent, temples short, some large setae along posterior margin of eyes. Clypeus almost smooth, anterior half with a row of five submarginal large setiferous punctures. Labrum smooth, dark brown and shiny, 1.1 times wider than long (male: length 0.66 mm, width 0.82 mm; female: length 0.74 mm, width 0.82 mm), anterior half converging, rounded along margins and apex, posterior half lateral margins slightly rounded; a large seta at the widest point near the rim, at the apex 4 setae, two exactly on the margin from the top, and two beneath the margin just on the top (Fig. 2d); posterior lateral half up to widest point with a fringe of short setae underneath. A pair of supraorbital setae on each side (Fig. 1d). Mentum with a central tooth, acuminate and sharp. Antennae with the first three antennomeres less densely pubescent with rather long setae, from the fourth antennomere densely pubescent with shorter setae, first and third antennomeres almost cylindrical, second and fourth subpyriform, the remaining depressed, slightly longer than wide, with a slight basal thin median longitudinal smooth area; last antennomere more or less acuminate.</p> <p> <i>Thorax</i>. Pronotum slightly cordiform (Fig. 1d), strongly transverse, 1.6 times wider than long (male: length 1.22 mm, width: 1.92 mm; female: length 1.25 mm, width 1.98 mm), maximum width just ahead of the middle length; surface covered with coarsely punctures, more or less uniformly distributed on all areas, bearing each one a long and fine brown-yellowish seta, intervals smooth; anterior angles rounded, anterior margin almost straight; posterior margin straight in the middle, oblique sinuate towards the posterior angles which are rounded and bear a long seta; anterior and posterior margins not margined, lateral margins with complete and distinct margination since the anterior angles, reaching the posterior angles, sinuate just anterior to posterior angles, without forming a tooth before the angles, a long seta in front of the widest part of pronotum, anterior angles with some large bristles; anterior transverse sulcus not distinct, pronotal base with a pair of round faint foveae near the posterior angles, a median slight sulcus in a flat and depressed area that reaches the posterior edge. Scutellum triangular, setiferous punctured. Prosternum coarsely punctured, without microsculpture.</p> <p> <i>Elytra</i> (Fig. 1d) 1.7 times longer than wide (male: length 4.62 mm, width 2.79 mm; female: length 4.88 mm, width 2.94 mm), subparallel-sided, widening slightly towards the posterior third, not covering the last two tergites; only seven striae visible, the first six well-marked, the seventh faint, all slightly punctured and not reaching the base and the apex; intervals slightly convex, without microreticulation, coarse setiferous punctured in two rows on 1 st –7 th intervals, decumbent seta brown-yellowish sub-erected and directed posteriad; lateral margin rounded in the shoulders, ending in deep furrow moderately densely punctured towards the scutellum. Scutellar striae visible between the two row of punctures in the anterior region of first interval. Basal pore present. Umbilicate series with 24 (male) and 29 (female) pores, irregular row in the first half, not interrupted in the middle although they are more separated from each other; 1 subapical pore shifted inward in the lengthening of the imaginary 8 th interval; apex with 4 extra pores, 2 in the lengthening of the imaginary 7 th and 6 th striae, respectively, and 2 in the lengthening of 5 th and 3 rd intervals; apical transparent membrane extending from sutural angle to the lengthening of the imaginary 8 th interval.</p> <p> The longitudinal sub-humeral orange band extends obliquely from the 6 th to the 2 nd intervals in the anterior region, reaching the intermediate region of the elytra in 3 rd to 5 th intervals (Fig. 1d).</p> <p> <i>Legs.</i> Brown coloured; all tarsomeres pubescent, first three fore tarsomeres not dilated, fourth tarsomere slightly triangulate; fore tibiae on the outer edge with two blunt spines.</p> <p> <i>Ventral surface</i>. Almost all underside blackish, last abdominal sternite brownish; whole underside, including abdominal sternites coarsely punctured and pubescent (yellowish color), except gula, ventral and lateral sides of neck. Pubescence of prosternum and proepisternum erect; pubescence of the remaining ventral sclerites dressed and directed posteriad. Elytral epipleura moderately punctured, pubescence dressed and directed posteriad.</p> <p> <i>Male genitalia</i> (Fig. 3c). Median lobe dilated in the median region, slightly constricted between basal bulb and shaft, apical margin rounded and slightly acuminated (dorsal view), apex sharp acuminated and downward (lateral view), ostium with one pair of thin and extensive scaled sclerotized stripes on dorsum, bending laterally downwards and backwards; left paramere longer than wide and straight, without distal tooth.</p> <p> <i>Female genitalia</i> (Fig. 4c). Gonocoxite 1 subtriangular; gonocoxite 2 largely sickle shaped, apex slightly acuminate; outer margin slightly curved, dorsal surface concave, almost all covered with numerous setae, inner margin with 7–8 setae; ventral surface convex, smooth.</p> <p> <b>Intraspecific variation.</b> There is some variability in the number of umbilicate elytral pores (24 to 29). There is also some variation in the number of subapical pores (male:1; female: 2) and in the location of the 4 apical extra pores in the lengthening of the imaginary 6 th striae (male) or 7 th (female), 6 th striae (male) or 7 th interval (female), 5 th intervals (male) or 6 th (female) and 3 rd intervals (male) or 4 th (female).</p> <p> <b>Etymology.</b> This species is named in honour of Peter Scḩle (Herrenberg, Germany), a well-known specialist on tiger and ground beetles of Africa who has strongly collaborated with us and kindly provided all the specimens of this new species.</p> <p> <b>Remarks.</b> The new species is more akin to <i>Macrocheilus scapularis</i> (Reiche, 1843) and <i>M. allardi</i> Basilewsky, 1957 than to the other African species by the elytral colour pattern (cf. Fig. 1d <i>vs</i> Figs. 11a and 1e). <i>Macrocheilus schuelei</i> <b>n. sp.</b> can be separated from the former species by the more transverse pronotum, the posterior angles of pronotum slightly obtuse and rounded at apex (acute and slightly rounded in <i>M. scapularis</i>), the legs totally brown (tibiae blackish in <i>M. scapularis</i>) and different shape of labrum (cf. Figs. 2d and 12a) and of median lobe of aedeagus (cf. Figs. 3c and 13b). The new species differs from <i>M. allardi</i> by the shorter body, the head, pronotum, scutellum, mouthparts and legs colour (cf. Figs. 1d and 1e), a lesser securiform shape of the last palpomere of maxillary palps, more transverse and different shape of pronotum and of labrum. <i>Macrocheilus schuelei</i> <b>n. sp.</b> differs from the other African species of this genus by the elytral colour pattern and the median lobe shape, among other external morphological characters.</p> <p> <b>Distribution</b>. Only known from Republic of Central Africa.</p>Published as part of <i>Serrano, Artur R. M., 2023, Afrotropical ground beetles of Macrocheilus Hope, 1838 (Coleoptera, Carabidae) description of four new species and faunistic notes, pp. 1-35 in Zootaxa 5256 (1)</i> on pages 7-12, DOI: 10.11646/zootaxa.5256.1.1, <a href="http://zenodo.org/record/7745281">http://zenodo.org/record/7745281</a>
[[alternative]]Raman Study of Folded Acoustic Phonons in Si/Ge Superlattice
No full text[[abstract]]This research presents three Raman Spectrums of Si/Ge superlattices growing on the substrate of Si by MBE. The period of superlattice samples N=5, the growing conditions of superlattice are: the Si-layer is 50nm；the Ge-layers are 2.2nm、3.8nm and 5.4nm. Measuring by TEM of samples firstly, the Si-layers are 50.18nm、48.65 nm and 48.89 nm；the Ge-layers are 2.46 nm、3.78 nm and 4.44 nm。
In the Spectrum, the peak of Si-Si mode is quite obvious；The peak of Ge-Ge mode is comparatively weak. In the room temperature, the peak of Si-Ge mode is quite unobvious due to the fewer periods.
Raman Spectrum of three superlattices shows many and obvious folded phonon signals in the low frequency (0 ~100 cm-1) area , so does the doublets of phonon are quite obvious. Fittting the frequency of folded phonons by Rytov’s theory finds that the Si-layers are 49.65nm、45.98 nm and 45.95 nm, the Ge-layers are 2.12 nm、3.78 nm and 5.01 nm. All the errors are within 6%, so Rytov’s theory is a good foundation to study Raman Spectrum of superlattice.
Fitting the intensity of folded spectrum of phonon with photoelastic mode , in the wavelength far away the energy of resonance ( As 476 nm) can get good result. Also getting the ratio of Si-layer thickness and the period of superlattice are 0.96（632 nm）、0.93（476 nm）and 0.93（476 nm）, compared with the result of fitting frequency of folded phonon by Rytov’s theory：0.96、0.92及0.90, matchs very well, except the 3% difference of sample-N107.
Besides, examining Ge-Ge mode in the spectrum with LCM, the roughness of Ge-layer can be examed, and the calculating layers are 2.22nm、3.83 nm and 5.37 nm, the difference is within 7% comparing with the result of fitting phonons.
In the various temperature (10 K~300 K) Raman Sprctrum, there are signals of continuous scattering of phonons around 200 cm-1 , and the lower the temperature, or the thinner the Ge-layer, the more obvious the continuous scattering of phonon is. We can find the phenomenon that E1 energy of Ge-layer is in the vicinity of 2.3 eV and distributed widely ,when we observe the folded phonon in low frequency, the resonance of Ge-Ge Mode, and the fluorescence in high frequency.
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