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71.
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73.
Esquena J Nestor J Vílchez A Aramaki K Solans C 《Langmuir : the ACS journal of surfaces and colloids》2012,28(33):12334-12340
A novel and simple single-step method for the preparation of meso/macroporous silica materials is described, which consists in templating in highly concentrated emulsions with a cubic liquid crystal in the continuous phase. Tetraethyl orthosilicate (TEOS) was solubilized in the aqueous continuous phase of highly concentrated emulsions stabilized by C(12)(EO)(8) and a PEO-PPO-PEO block copolymer nonionic surfactant, with a cubic liquid crystalline phase of the Fd3m type. The resulting silica materials were characterized by small-angle X-ray scattering, nitrogen sorption and transmission electron microscopy. The results showed that a dual pore size distribution was obtained, consisting of mesopores in the nanometer range and macropores between 1 and 5 μm. These dual meso/macroporous silicas with bimodal pore size distribution can possess specific surface areas higher than 400 m(2)/g. 相似文献
74.
Castro K Pérez-Alonso M Rodríguez-Laso MD Etxebarria N Madariaga JM 《Analytical and bioanalytical chemistry》2007,387(3):847-860
Non-destructive and non-invasive micro-Raman fibre optic and micro-XRF analyses were performed to study a wallpaper from the
beginning of the 19th century. The complementarity of these two non-destructive techniques is shown in this work. The analysed
artwork is considered one of the most beautiful wallpapers ever manufactured according to the catalogues and books; it is
known as Chasse de Compiègne, manufactured by Jacquemart, Paris, in 1812. During the analysis, an unexpected pigment was detected by both analytical techniques:
lead-tin yellow type II. This pigment was used until ca. 1750, when other yellow pigments replaced it, thus it is very difficult
to find it in paintings afterwards. Together with this pigment, red lead, Prussian blue, brochantite, yellow iron oxide, calcium
carbonate, vermilion, carbon black of animal origin (bone black), lead white, and raw and burnt sienna were also determined
by combining the analytical information provided by both techniques. A possible degradation of brochantite to antlerite is
also discussed. 相似文献
75.
Scandale W Vomiero A Baricordi S Dalpiaz P Fiorini M Guidi V Mazzolari A Della Mea G Milan R Ambrosi G Bertucci B Burger WJ Zuccon P Cavoto G Luci C Santacesaria R Valente P Vallazza E Afonin AG Chesnokov YA Maisheev VA Yazynin IA Kovalenko AD Taratin AM Denisov AS Gavrikov YA Ivanov YM Lapina LP Malyarenko LG Skorobogatov VV Suvorov VM Vavilov SA Bolognini D Hasan S Mozzanica A Prest M 《Physical review letters》2008,101(16):164801
Beam deflection due to axial channeling in a silicon crystal bent along the 111 axis was observed with 400 GeV/c protons at the CERN Super Proton Synchrotron. The condition for doughnut scattering of protons by the atomic strings of the crystal was attained. Such a condition allowed one to observe a beam deflection of 50 murad with about 30% efficiency. The contribution of hyperchanneled states of protons to the observed beam deflection was less than 2% according to simulation results. 相似文献
76.
Castro K Sarmiento A Maguregui M Martínez-Arkarazo I Etxebarria N Angulo M Barrutia MU González-Cembellín JM Madariaga JM 《Analytical and bioanalytical chemistry》2008,392(4):755-763
A complete study of several English polychromed alabaster sculptures is presented. The support, pigment, and binders were
characterised by combining μEDXRF, μRaman, and FTIR spectroscopies. Among the pigments, minium, vermilion, lead white, carbon
black, red iron oxide, and a degraded green copper pigment were determined, together with gold leaf. The presence of the rare
mineral moolooite (copper oxalate) was also found as a degradation product in the green areas, where weddellite (calcium oxalate
dihydrate) was also determined. These facts, together with degradation of the green copper pigment, suggest microbiological
degradation of the original materials. Remains of glue and a varnish were also determined by FTIR spectroscopy and principal-components
analysis (PCA) of the spectra. Finally, PCA analysis was carried out to confirm whether the pieces came from the same quarry. 相似文献
77.
Focused ultrasonic-assisted extraction (FUSE) is a new and particular technique based on the cavitation effect. In this work, the focused ultrasound assisted extraction was studied and developed for the extraction of polycyclic aromatic hydrocarbons from marine sediments and mussel tissues. The variables influencing the extraction (amplitude of the ultrasound pulse, the extraction time and the solvent) were studied by a full factorial design and a central composite design. As a result, flat response surfaces were obtained and the most convenient conditions were 45% of ultrasound amplitude, 120 s of extraction time and 5 mL of acetone. Both accuracy and precision of the method were evaluated by means of two certified reference materials (marine sediment and mussel tissue) and the results were also compared to those obtained by microwave assisted extraction. 相似文献
78.
W. Scandale A. Vomiero E. Bagli S. Baricordi P. Dalpiaz M. Fiorini V. Guidi A. Mazzolari D. Vincenzi R. Milan Gianantonio Della Mea E. Vallazza A.G. Afonin Yu.A. Chesnokov V.A. Maisheev I.A. Yazynin V.M. Golovatyuk A.D. Kovalenko A.M. Taratin A.S. Denisov Yu.A. Gavrikov Yu.M. Ivanov L.P. Lapina L.G. Malyarenko V.V. Skorobogatov V.M. Suvorov S.A. Vavilov D. Bolognini S. Hasan M. Prest 《Physics letters. [Part B]》2010
Different kinds of deflection in a silicon crystal bent along the 〈111〉 axis was observed for 150 GeV/c negative particles, mainly π− mesons, at one of the secondary beams of the CERN SPS. The whole beam was deflected to one side in quasi-bound states of doughnut scattering (DSB) by atomic strings with the efficiency (95.4 ± 0.2)% and with the peak position close to the bend crystal angle, α=185 μrad. It was observed volume capture of π− mesons into the DSB states with a probability higher than 7%. A beam deflection opposite to the crystal bend was observed for some orientations of the crystal axis due to doughnut scattering and subsequent multiple volume reflections of π− mesons by different bent planes crossing the axis. 相似文献
79.
Flávia?Rodrigues?de Oliveira Silva Maria?Helena?Bellini Vivian?Regina?Trist?o Nestor?Schor Nilson?Dias?VieiraJr. Lilia?Coronato?Courrol 《Journal of fluorescence》2010,20(6):1159-1165
Prostate cancer is one of the most common types of cancer in men, and unfortunately many prostate tumours remain asymptomatic
until they reach advanced stages. Diagnosis is typically performed through Prostate-Specific Antigen (PSA) quantification,
Digital Rectal Examination (DRE) and Transrectal Ultrasonography (TU). The antigen (PSA) is secreted by all prostatic epithelial
cells and not exclusively by cancerous ones, so its concentration also increases in the presence of other prostatic diseases.
DRE and TU are not reliable for early detection, when histological analysis of prostate tissue obtained from a biopsy is necessary.
In this context, fluorescence techniques are very important for the diagnosis of cancer. In this paper we explore the potential
of using endogenous phorphyrin blood fluorescence as tumour marker for prostate cancer. Substances such as porphyrin derivatives
accumulate substantially more in tumours than in normal tissues; thus, measuring blood porphyrin concentration by autofluorescence
intensity may provide a good parameter for determining tumour stage. In this study, the autofluorescence of blood porphyrin
was analyzed using fluorescence and excitation spectroscopy on healthy male NUDE mice and in those with prostate cancer induced
by inoculation of DU145 cells. A significant contrast between the blood of normal and cancer subjects could be established.
Blood porphyrin fluorophore showed an enhancement on the fluorescence band around 632 nm following tumour growth. Fluorescence
detection has advantages over other light-based investigation methods: high sensitivity, high speed and safety. However it
does carry the drawback of low specificity of detection. The extraction of blood porphyrin using acetone can solve this problem,
since optical excitation of further molecular species can be excluded, and light scattering from blood samples is negligible. 相似文献
80.
J. V. Alvarez-Bravo N. Bolognini L. Arizmendi 《Applied physics. B, Lasers and optics》1996,62(2):159-164
Changes in the angular Bragg selectivity of volume holograms stored in photorefractive LiNbO3 are analysed for different experimental conditions in the transmission geometry. The effects of the refractive-index-change amplitude, the grating period, the modulation depth, and the wave-front modulation of the signal beam are considered. A very good agreement of the results with the off-Bragg diffraction theory is observed. 相似文献