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141.
G. Vergara M. T. Montojo M. C. Torquemada M. T. Rodrigo F. J. Sánchez L. J. Gómez R. M. Almazán M. Verdú P. Rodríguez V. Villamayor M. Álvarez J. Diezhandino J. Plaza I. Catalán 《Opto-Electronics Review》2007,15(2):110-117
The existing technology for uncooled MWIR photon detectors based on polycrystalline lead salts is stigmatized for being a
50-year-old technology. It has been traditionally relegated to single-element detectors and relatively small linear arrays
due to the limitations imposed by its standard manufacture process based on a chemical bath deposition technique (CBD) developed
more than 40 years ago. Recently, an innovative method for processing detectors, based on a vapour phase deposition (VPD)
technique, has allowed manufacturing the first 2D array of polycrystalline PbSe with good electro optical characteristics.
The new method of processing PbSe is an all silicon technology and it is compatible with standard CMOS circuitry. In addition
to its affordability, VPD PbSe constitutes a perfect candidate to fill the existing gap in the photonic and uncooled IR imaging
detectors sensitive to the MWIR photons. The perspectives opened are numerous and very important, converting the old PbSe
detector in a serious alternative to others uncooled technologies in the low cost IR detection market. The number of potential
applications is huge, some of them with high commercial impact such as personal IR imagers, enhanced vision systems for automotive
applications and other not less important in the security/defence domain such as sensors for active protection systems (APS)
or low cost seekers.
Despite the fact, unanimously accepted, that uncooled will dominate the majority of the future IR detection applications,
today, thermal detectors are the unique plausible alternative. There is plenty of room for photonic uncooled and complementary
alternatives are needed. This work allocates polycrystalline PbSe in the current panorama of the uncooled IR detectors, underlining
its potentiality in two areas of interest, i.e., very low cost imaging IR detectors and MWIR fast uncooled detectors for security
and defence applications. The new method of processing again converts PbSe into an emerging technology. 相似文献
142.
Pernites R Vergara A Yago A Cui K Advincula R 《Chemical communications (Cambridge, England)》2011,47(35):9810-9812
A facile approach of making scalable nanocomposite and electro-patterned films using graphene oxide (GO) and poly(N-vinylcarbazole) (PVK) is reported. The method involves the layering of polystyrene colloidal templates, electrodeposition of the composite film on template array, and finally removal of the sacrificial templates to reveal the patterned GO-PVK arrays. 相似文献
143.
Vicente Vergara 《Calculus of Variations and Partial Differential Equations》2011,40(3-4):319-334
We prove that any global bounded solution of the nonlinear evolutionary integral equation $$\dot{u}(t) + \int\limits_0^t a(t-s)\mathcal{E}'(u(s))ds =f(t), \quad t >0 $$ tends to a single equilibrium state for long time (i.e., ${\mathcal{E}'(\vartheta)=0}$ where ${\vartheta= \lim_{t \rightarrow \infty} u(t)}$ on a real Hilbert space), where ${\mathcal{E}'}$ is the Fréchet derivative of a functional ${\mathcal{E}}$ , which satisfies the ?ojasiewicz?CSimon inequality near ${\vartheta}$ . The vector-valued function f and the scalar kernel a satisfy suitable conditions. 相似文献
144.
Novel liquid crystal materials based on 3,4-di-n-alkoxybenzoylthiosemicarbazides (3a–h, n = 5–10, 12, 14) were synthesised. The mesomorphic properties of these compounds were characterised and studied by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. Compound 3a did not show mesomorphic properties; 3b shows a monotropic hexagonal columnar (Colh) phase. Compounds 3c–h display an enantiotropic Colh phase. The mesomorphic properties were found to be dependent on the length of alkoxy side chains. In N,N-dimethylformamide solution, all the compounds displayed a room temperature emission with λmax at 361–332 nm. A thermogravimetric analysis also was performed. 相似文献
145.
Jeong Jae Wie David H. Wang Vincent P. Tondiglia Nelson V. Tabiryan Rafael O. Vergara‐Toloza Loon‐Seng Tan Timothy J. White 《Macromolecular rapid communications》2014,35(24):2050-2056
Light is a readily available and sustainable energy source. Transduction of light into mechanical work or electricity in functional materials, composites, or systems has other potential advantages derived from the ability to remotely, spatially, and temporally control triggering by light. Toward this end, this work examines photoinduced piezoelectric (photopiezoelectric) effects in laminate composites prepared from photoresponsive polymeric materials and the piezoelectric polymer polyvinylidene fluoride (PVDF). In the geometry studied here, photopiezoelectric conversion is shown to strongly depend on the photomechanical properties inherent to the azobenzene‐functionalized polyimides. Based on prior examinations of photomechanical effects in azobenzene‐functionalized polyimides, this investigation focuses on amorphous materials and systematically varies the concentration of azobenzene in the copolymers. The baseline photomechanical response of the set of polyimides is characterized in cantilever deflection experiments. To improve the photomechanical response of the materials and enhance the electrical conversion, the polyimides are drawn to increase the magnitude of the deflection as well as photogenerated stress. In laminate composites, the photomechanical response of the materials in sequenced light exposure is shown to transduce light energy into electrical energy. The frequency of the photopiezoelectric response of the composite can match the frequency of the sequenced light exposing the films.
146.
Vitagliano L Vergara A Bonomi G Merlino A Verde C di Prisco G Howes BD Smulevich G Mazzarella L 《Journal of the American Chemical Society》2008,130(32):10527-10535
147.
P. Jara‐Ulloa P. Salgado‐Figueroa C. Yañez L. J. Núñez‐Vergara J. A. Squella 《Electroanalysis》2012,24(8):1751-1757
We report the adsorptive voltammetric determination of nifedipine on multiwalled carbon nanotubes (MWCNT)‐modified glassy carbon electrode (GCE). Nifedipine was adsorbed on the MWCNT and then reduced using linear sweep and cyclic voltammetry (LSV and CV). Parameters such as pH and accumulation time were tested. The MWCNT‐modified GCE showed enhanced currents and good signal‐to‐noise characteristics in comparison with the bare GCE. Consecutive measurements with the modified electrode were highly repeatable and reproducible. The MWCNT/GCE was used for the determination of nifedipine and is recommended for quantitation in dissolution test studies. In this study we have tested normal and extended‐release pharmaceutical formulations of nifedipine using USP apparatus 2 and tracking the released drug in solution by the proposed voltammetric method. The main advantage of the voltammetric determination is the feasibility to detect the drug in‐situ avoiding tedious intermediate steps such as filtration, collection and replenishment of sample solutions. This work seeks to demonstrate the feasibility of applying voltammetric techniques in dissolution test studies. 相似文献
148.
A fast and simple method to analyze pyrethroids as well as other components of frequently used domestic insecticide preparations in indoor air is presented. The proposed method, based on sampling with an adsorbent followed by ultrasound-assisted solvent extraction, was developed with the aim to simplify the traditional extraction methodologies applied up to date to determine pesticides in air. The analytes were retained on a very small amount of adsorbent, which allowed using solely 1 mL of solvent for desorption. The quantification was performed by gas chromatography with microelectron-capture detection (GC-muECD) and gas chromatography coupled to mass spectrometry (GC-MS). The influence of main factors involved in the ultrasound-assisted solvent extraction step (type of adsorbent and type of solvent, solvent volume and extraction time) was studied using an experimental design approach to account for possible factor interactions. The sampling step was studied for two adsorbents (Tenax TA and Florisil), finding that 1 m(3) air could be sampled without losses of analytes. In this way, the analysis of pyrethroids in air by the proposed method could be carried out within a total time shorter than an hour, including sampling. Linearity was demonstrated in a wide concentration range. Efficiency of the total sampling-extraction process was studied at several concentration levels (2, 10, 100 and 1000 ng/m(3)), obtaining quantitative recoveries for all compounds, with good precision (RSD < 10%). Method detection limits were below 1 ng/m(3) in air when GC-muECD was employed, and about one order of magnitude higher for GC-MS. In addition, the proposed method was applied to real samples collected in contaminated closed rooms, in which some of the target compounds were determined. 相似文献
149.
Bayliss RD Berry FJ de Laune BP Greaves C Helgason O Marco JF Thomas MF Vergara L Whitaker MJ 《J Phys Condens Matter》2012,24(27):276001
Ferrous antimonite, FeSb(2)O(4), which is isostructural with Pb(3)O(4), and some lead-?and cobalt-doped variants of composition FeSb(1.5)Pb(0.5)O(4) and Co(0.5)Fe(0.5)Sb(1.5)Pb(0.5)O(4) have been examined by (57)Fe and (121)Sb?M?ssbauer spectroscopy. Antimony is present as Sb(3+). The presence of Pb(2+) on the antimony site induces partial oxidation of Fe(2+) to Fe(3+). There is no Verwey-type transition in which electrons are shared between iron in different oxidation states. The quasi-one-dimensional magnetic structure gives rise to situations in which weakly coupled Fe(2+) ions can coexist in a non-magnetic state alongside Fe(3+) ions in a magnetically ordered state. 相似文献
150.
Herminia I. Calvete Carmen Galé Stephan Dempe Sebastian Lohse 《Journal of Global Optimization》2012,53(3):573-586
Bilevel programming involves two optimization problems where the constraint region of the upper level problem is implicitly determined by another optimization problem. In this paper we focus on bilevel problems over polyhedra with upper level constraints involving lower level variables. On the one hand, under the uniqueness of the optimal solution of the lower level problem, we prove that the fact that the objective functions of both levels are quasiconcave characterizes the property of the existence of an extreme point of the polyhedron defined by the whole set of constraints which is an optimal solution of the bilevel problem. An example is used to show that this property is in general violated if the optimal solution of the lower level problem is not unique. On the other hand, if the lower level objective function is not quasiconcave but convex quadratic, assuming the optimistic approach we prove that the optimal solution is attained at an extreme point of an ??enlarged?? polyhedron. 相似文献