Search results for "Note"

Rounding noise effects’ reduction for estimated movement of speckle patterns

2018

The problem of resolution enhancement for speckle patterns analysis-based movement estimation is considered. In our previous publications we showed that this movement represents the corresponding tilt vibrations of the illuminated object and can be measured as a relative spatial shift between time adjacent images of the speckle pattern. In this paper we show how to overcome the resolution limitation obtained when using an optical sensor available in an optical mouse and which measures the Cartesian coordinates of the shift as an integer number of pixels. To overcome such a resolution limitation, it is proposed here to use simultaneous measurements from the same illuminated spot by a few cam…

Phase error analysis of clipped waveforms in surface topography measurement using projected fringes

2021

Abstract When working with the method of projected fringes outside the optical laboratory one often encounters the problem of uncontrollable ambient light. This might cause saturation of the camera which in turn results in clipping of the fringes. Since standard theories describing phase-shifting techniques assume the projected fringes to be purely sinusoidal, such clipping will result in measurement error. In this paper a detailed analysis of this problem is given, and relations between phase errors, the amount of fringe clipping and the number of phase steps are found. Moreover, the phase difference between the clipped and the unclipped fringes is described. This investigation is based on…

Raman spectroscopy study of β-irradiated silica glass

2003

International audience; Natural and synthetic silica glass samples with different OH content have been submitted to β-irradiation at different doses from 106 to 5 × 109 Gy in a Van de Graaff accelerator. Structural changes under irradiation have been analyzed by Raman spectroscopy. The main findings are: (i) a decrease of the Si–O–Si angular dispersion and the average Si–O–Si angle as a function of dose and (ii) an increase of number of three-membered SiO4 ring concentration during irradiation. These results show therefore that purely electronic excitation from β-irradiation induces in a-SiO2 small but significant structural changes of the SiO4 membered ring statistics (size and dispersion)…

A Biocatalytic Nanomaterial for the Label-Free Detection of Virus-Like Particles

2017

International audience; The design of nanomaterials that are capable of specific and sensitive biomolecular recognition is an on-going challenge in the chemical and biochemical sciences. A number of sophisticated artificial systems have been designed to specifically recognize a variety of targets. However, methods based on natural biomolecular detection systems using antibodies are often superior. Besides greater affinity and selectivity, antibodies can be easily coupled to enzymatic systems that act as signal amplifiers, thus permitting impressively low detection limits. The possibility to translate this concept to artificial recognition systems remains limited due to design incompatibilit…

Corrigendum to “The effect of silica nanoparticles on the morphology, mechanical properties and thermal degradation kinetics of PMMA” [Polym Degrad S…

2012

Silicatein: Nanobiotechnological and Biomedical Applications

2009

Silica-based materials are used in many high-tech products including microelectronics, optoelectronics, and catalysts. Siliceous sponges (Demospongiae and Hexactinellida) are unique in their ability to synthesize silica enzymatically. We have cloned the silica-forming enzymes, silicateins, from both demosponges (marine and freshwater sponges) and hexactinellid sponges. The recombinant enzymes allow the synthesis of silica under environmentally benign ambient conditions, while the technical (chemical) production of silica commonly requires high temperatures and pressures, and extremes of pH. Silicateins can be used for the fabrication of highly-ordered inorganic–organic composite materials w…

Biogenic Inorganic Polysilicates (Biosilica): Formation and Biomedical Applications

2013

The siliceous sponges, the demosponges and hexactinellid glass sponges, are unique in their ability to form biosilica structures with complex architectures through an enzyme-catalyzed mechanism. The biosilica skeleton of these sponges with its hierarchically structure and exceptional opto-mechanical properties has turned out to be an excellent model for the design of biomimetic nanomaterials with novel property combinations. In addition, biosilica shows morphogenetic activity that offers novel applications in the field of bone tissue engineering and repair. In recent years, much progress has been achieved towards the understanding of the principal enzymes, the silicateins that form the spon…

Apposition of silica lamellae during growth of spicules in the demosponge Suberites domuncula: Biological/biochemical studies and chemical/biomimetic…

2006

Recently it has been discovered that the formation of the siliceous spicules of Demospongiae proceeds enzymatically (via silicatein) and occurs matrix guided (on galectin strings). In addition, it could be demonstrated that silicatein, if immobilized onto inorganic surfaces, provides the template for the synthesis of biosilica. In order to understand the formation of spicules in the intact organism, detailed studies with primmorphs from Suberites domuncula have been performed. The demosponge spicules are formed from several silica lamellae which are concentrically arranged around the axial canal, harboring the axial filament composed of silicatein. Now we show that the appositional growth o…

High Fluorescence of Thioflavin T Confined in Mesoporous Silica Xerogels

2013

Trapping of organic molecules and dyes within nanoporous matrices is of great interest for the potential creation of new materials with tailored features and, thus, different possible applications ranging from nanomedicine to material science. The understanding of the physical basis of entrapment and the spectral properties of the guest molecules within the host matrix is an essential prerequisite for the design and control of the properties of these materials. In this work, we show that a mesoporous silica xerogel can efficiently trap the dye thioflavin T (ThT, a molecule used as a marker of amyloid fibrils and with potential drug benefits), sequestering it from an aqueous solution and pro…

Self-limiting and complete oxidation of silicon nanostructures produced by laser ablation in water

2016

Oxidized Silicon nanomaterials produced by 1064 nm pulsed laser ablation in deionized water are investigated. High-resolution transmission electron microscopy coupled with energy dispersive X-ray spectroscopy allows to characterize the structural and chemical properties at a sub-nanometric scale. This analysis clarifies that laser ablation induces both self-limiting and complete oxidation processes which produce polycrystalline Si surrounded by a layer of SiO2 and amorphous fully oxidized SiO2, respectively. These nanostructures exhibit a composite luminescence spectrum which is investigated by time-resolved spectroscopy with a tunable laser excitation. The origin of the observed luminescen…