1,721,064 research outputs found
A SURFACE PLASMON RESONANCE BASED SENSING METHOD AND SENSING SYSTEM
No full textthe invention relates to a surface plasmon resonance (SPR) sensing methods and to a SPR sensing system suitable for use in chemical, biochemical, biological, biomedical, pharmaceutical and physical testing
Optical characterization of self-assembled Ge dots on Silicon
No full textSelf assembled quantum dots of Ge were obtained by magnetron sputter epitaxy of seven monolayers of Ge on a 33nm thick undoped Si buffer grown on top of a p-doped (100) Si substrate. The samples obtained in this manner were then capped with an increasing number of silicon layers in order to study the effect of Si deposition on the strain and the morphology of the dots. They were characterized ``ex situ'' by spectroscopic ellipsometry and Raman spectroscopy. The optical experiments revealed well defined differences between the capped and uncapped samples and among samples with different cap thicknesses. By monitoring the energy and the splitting of the E0’, E1 and E2 interband optical transitions of Ge and the Ge-Si vibrational mode, the optical measurements evidence strain effects as well as the formation of SiGe alloy, in agreement with the ``in situ'' STM measurements
Plasmonic resonances in nanostructured gold/polymer surfaces by colloidal lithography
No full textWe investigate nanostructured surfaces consisting of a
hexagonal lattice of polymeric pillars embedded in a gold
matrix. These systems are prepared by a new fabrication
technique based on plasma assisted deposition and colloidal
lithography. A complete characterization of such surfaces is
performed by angle resolved reflectance and transmittance
measurements. Both delocalized and localized plasmonic
modes can be identified: their reciprocal interplay allows to
observe spectral features and to detect refractive index changes
related to one of the sample interfaces by measurements
performed with a light beam incident from the opposite side.
This intriguing behaviour, together with ease of use and low
cost of the deposition procedure, make this kind of nanostructures
particularly interesting in biosensing applications
A Novel Portable Surface Plasmon Resonance Based Imaging Instrument for On-Site Multi-Analyte Detection
No full textIn the last decade the need for portable Surface Plasmon Resonance (SPR) biosensors capable of on-site simultaneous multiple assays increased steadily. Several devices are available affected, however, by limitations in terms of costs, size, complexity and portability. A compact low-cost SPRi biosensor based on a novel method for multi-analyte detection is presented. The prototype consists of a nanohole array biochip integrated with a compact optics and an elaboration system. A CMOS image sensor captures reflected light from the biochip surface irradiated by a 830 nm LED. The entire system is managed by an ARM9 processor. The biosensor was able to detect a ~10-5 RIU change in the refractive index without analyte receptors at a glycerol concentration equal to 0.2%. Results are available in 14 seconds on LCD display and immediately stored to external SD memory. Preliminary experiments confirmed the strong biosensor's usability in a wide range of applications and field
Dispositivo per il rilevamento di composti molecolari basato su risonanza plasmonica di superficie
No full textIn recent years, several approaches have been developed to carry out biosensors based on Localized Surface Plasmon Resonance (LSPR). However, the high costs of nanostructures fabrications and absence of autonomous portable devices strongly limit the extensive use of LSPR biosensors outside the research laboratories.
We designed, carry out and tested a novel low cost, multiparametric stand-alone LSPR imaging instrument for biosensing applications. This compact device (15 x 6 x 17 cm size and < 500g weight) consist on a nanohole array biochip integrated with a microfluidic layer and an elaboration system. An optical apparatus focuses a light beam from an IR LED source and a digital image sensor captures the reflected light from the biochip surface. The signals are processed by the embedded ARM processor and showed in a touchscreen display by a friendly end-user application, without the use of other external computational devices.
Moreover, we propose an extremely simple analytical method to reduce image noise without any sophisticated temperature control or external luminosity change compensation.
The device sensitivity of 6 x 10-5 Refractive Index Unit (RIU) was proved using glycerol solutions with different concentrations. We demonstrated the feasibility of our system in biomolecular detection, by monitoring the Ab-PTX3 antibody, as a test revealing instrument potentialities in detection of antibodies.
The obtained results confirmed the potential usefulness of the proposed system in several biomedical applications such as medical diagnostic, immunoassays or fast mass screening without the aid of specialized laboratory or trained personne
Interaction among plasmonic resonances in a gold film embedding a two-dimensional array of polymeric nanopillars
No full textNanostructured surfaces have proven to be effective in controlling the electric field distribution and triggering
a series of interesting physical effects. In particular, ordered metallic lattices with a typical size of the same
order of magnitude of the wavelength of the incident radiation exhibit extraordinary transmission and reflection
properties and represent a sensitive tool to exploit surface plasmon resonance for sensing applications. We
investigated, either by experimental structural and optical measurements or by modeling and calculations, samples
consisting of a two-dimensional array of polymeric pillars embedded in a gold film. In particular, we analyzed
the dependence of the plasmonic resonance on the pillar size. We showed that a peculiar interplay among
localized modes and propagating surface plasmon polaritons exists for some selected conditions and affects
the spectral distribution, lifetime, and field configuration of the plasmonic excitations
Surface analysis of functionalized substrates for the nucleation and crystallization of pharmaceutical molecules
Full text linkNucleation represents the core of a variety of natural processes, ranging from ice crystal formation to protein aggregation, which can occur homogeneously or heterogeneously, depending on whether aggregation mechanism involves the presence of single or multiple phases. Recently, the role of external surface features on crystallization of active pharmaceutical ingredients (APIs) is being investigated by relating surface chemistry and morphology to nucleation kinetics and polymorph selection.1
Surface functionalization using SAMs has been largely investigated and applied to different substrates and constitutes one of the most robust methods available to obtain well controlled functionalized surfaces.2,3,,4 In the present study, the use of glass substrates functionalized with self-assembly of trimethoxysilanes differing for their head group chemistry for the nucleation and crystallization of small pharmaceutical molecules was investigated. Silane anchoring was achieved via wet chemistry-based route whilst systematic characterisation of morphology and chemistry was carried on in order to determine the influence of different parameters (Figure 1). Assessment of effective functionalization was carried out by means of contact angle and surface Z-potential analyses, whilst the surface chemistry of functionalized glass was probed using XPS and ToF SIMS. Lastly, AFM was adopted for the characterization of surface topography. High-quality monolayers carrying thiol, methacrylate and glycidyloxy exposed groups were successfully synthesized whereas in the case of amino-terminated silanes surface roughness dramatically increased and correlation between ideal and experimental elemental ratios characterizing the monolayer was not achieved. Nucleation and crystallization of biopharmaceutical molecules was also carried out by studying aspirin and paracetamol crystallization out in a thin-film solution deposited onto SAMs. Crystallization outcome was studied according to kinetic and thermodynamic aspects by optical microscopy, whilst crystal orientation and form were evaluated by means of X-Ray Diffractometry (XRD). Finally, preliminary results on nanostructurated surfaces will be also presented
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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