27 research outputs found
Synthetic protein-conductive membrane nanopores built with DNA
Nanopores are key in portable sequencing and research given their ability to transport elongated DNA or small bioactive molecules through narrow transmembrane channels. Transport of folded proteins could lead to similar scientific and technological benefits. Yet this has not been realised due to the shortage of wide and structurally defined natural pores. Here we report that a synthetic nanopore designed via DNA nanotechnology can accommodate folded proteins. Transport of fluorescent proteins through single pores is kinetically analysed using massively parallel optical readout with transparent silicon-on-insulator cavity chips vs. electrical recordings to reveal an at least 20-fold higher speed for the electrically driven movement. Pores nevertheless allow a high diffusive flux of more than 66 molecules per second that can also be directed beyond equillibria. The pores may be exploited to sense diagnostically relevant proteins with portable analysis technology, to create molecular gates for drug delivery, or to build synthetic cells
Hardware Approach for Real Time Machine Stereo Vision
Image processing is an effective tool for the analysis of optical sensor information for driver assistance systems and controlling of autonomous robots. Algorithms for image processing are often very complex and costly in terms of computation. In robotics and driver assistance systems, real-time processing is necessary. Signal processing algorithms must often be drastically modified so they can be implemented in the hardware. This task is especially difficult for continuous real-time processing at high speeds. This article describes a hardware-software co-design for a multi-object position sensor based on a stereophotogrammetric measuring method. In order to cover a large measuring area, an optimized algorithm based on an image pyramid is implemented in an FPGA as a parallel hardware solution for depth map calculation. Object recognition and tracking are then executed in real-time in a processor with help of software. For this task a statistical cluster method is used. Stabilization of the tracking is realized through use of a Kalman filter. Keywords: stereophotogrammetry, hardware-software co-design, FPGA, 3-d image analysis, real-time, clustering and tracking
La spectroscopie dans l'Ultraviolet sous vide et PhotoÊlectronique des FluoroÊtylènes. Les 1,1-, cis- et trans-C2H2FCl.
The vacuum ultraviolet absorption spectra of the three fluorochloroethene isomers were measured in the 6-13 eV photon energy range. Additionally, the HeI and NeI photoelectron spectra were recorded. The assignment of the various photoelectron bands is based on MNDO calculations. The vaccum UV absorption spectral features were classified in terms of Rydberg series converging to the first and second ionization energy. Besides the typical pi-pi* transition, other valence transitions were observed and tentatively assigned. In the geminal isomer spectrum the dominant Rydberg series converge to the first ionization limit at 10.02 eV, in the cis and trans isomers the most intense Rydberg transitions converge to the second ionization energy at 11.87 and 12.03 eV respectively. The first ionization energies of these latter compounds, obtained by Rydberg series analysis, are 9.89 and 9.87 eV respectively. An assignment of the vibrational structure observed in both spectra is proposed.ARC - Actions de recherche concertĂŠe
Transparent Nanopore Cavity Arrays Enable Highly Parallelized Optical Studies of Single Membrane Proteins on Chip
Membrane
proteins involved in transport processes are key targets
for pharmaceutical research and industry. Despite continuous improvements
and new developments in the field of electrical readouts for the analysis
of transport kinetics, a well-suited methodology for high-throughput
characterization of single transporters with nonionic substrates and
slow turnover rates is still lacking. Here, we report on a novel architecture
of silicon chips with embedded nanopore microcavities, based on a
silicon-on-insulator technology for high-throughput optical readouts.
Arrays containing more than 14âŻ000 inverted-pyramidal cavities
of 50 femtoliter volumes and 80 nm circular pore openings were constructed
via high-resolution electron-beam lithography in combination with
reactive ion etching and anisotropic wet etching. These cavities feature
both, an optically transparent bottom and top cap. Atomic force microscopy
analysis reveals an overall extremely smooth chip surface, particularly
in the vicinity of the nanopores, which exhibits well-defined edges.
Our unprecedented transparent chip design provides parallel and independent
fluorescent readout of both cavities and buffer reservoir for unbiased
single-transporter recordings. Spreading of large unilamellar vesicles
with efficiencies up to 96% created nanopore-supported lipid bilayers,
which are stable for more than 1 day. A high lipid mobility in the
supported membrane was determined by fluorescent recovery after photobleaching.
Flux kinetics of Îą-hemolysin were characterized at single-pore
resolution with a rate constant of 0.96 Âą 0.06 Ă 10<sup>â3</sup> s<sup>â1</sup>. Here, we deliver an ideal
chip platform for pharmaceutical research, which features high parallelism
and throughput, synergistically combined with single-transporter resolution
Synthetic protein-conductive membrane nanopores built with DNA
Nanopores are key in portable sequencing and research given their ability to transport elongated DNA or small bioactive molecules through narrow transmembrane channels. Transport of folded proteins could lead to similar scientific and technological benefits. Yet this has not been realised due to the shortage of wide and structurally defined natural pores. Here we report that a synthetic nanopore designed via DNA nanotechnology can accommodate folded proteins. Transport of fluorescent proteins through single pores is kinetically analysed using massively parallel optical readout with transparent silicon-on-insulator cavity chips vs. electrical recordings to reveal an at least 20-fold higher speed for the electrically driven movement. Pores nevertheless allow a high diffusive flux of more than 66 molecules per second that can also be directed beyond equillibria. The pores may be exploited to sense diagnostically relevant proteins with portable analysis technology, to create molecular gates for drug delivery, or to build synthetic cells
AnalĂ˝za visuĂĄlnĂho vzhledu nervovĂ˝ch vlĂĄken na sĂtnici v obrazech s vysokĂ˝m rozliĹĄenĂm z fundus kamery: Studie na zdravĂ˝ch jedincĂch
The retinal ganglion axons are an important part of the visual system, which can be directly observed by fundus camera. The layer they form together inside the retina is the retinal nerve fiber layer (RNFL). This paper describes results of a texture RNFL analysis in color fundus photographs and compares these results with quantitative measurement of RNFL thickness obtained from optical coherence tomography on normal subjects. It is shown that local mean value, standard deviation, and Shannon entropy extracted from the green and blue channel of fundus images are correlated with corresponding RNFL thickness. The linear correlation coefficients achieved values 0.694, 0.547, and 0.512 for respective features measured on 439 retinal positions in the peripapillary area from 23 eyes of 15 different normal subjects.ÄlĂĄnek se zabĂ˝vĂĄ texturnĂ analĂ˝zou vrstvy nervovĂ˝ch vlĂĄken na sĂtnici v obrazech z fundus kamery. VĂ˝sledky tĂŠto analĂ˝zy jsou porovnĂĄny s tlouĹĄĹĽkou tĂŠto vrstvy, kterĂĄ byla zmÄĹena pomocĂ optickĂŠho koherentnĂho tomografu. KorelaÄnĂ koeficient mezi tĹemi nejlepĹĄĂmi texturnĂmi pĹĂznaky a tlouĹĄĹĽkou byl 0.694, 0.547, and 0.512. AnaĂ˝za byla provedena na 439 mĂstech na sĂtnici ve 23 snĂmcĂch zĂskanĂ˝ch z 15 subjektĹŻ