Long-term operation of a multi-channel cosmic muon system based on scintillation counters with MRS APD light readout

A Cosmic Ray Test Facility (CRTF) is the first large-scale implementation of a scintillation triggering system based on a new scintillation technique known as START. In START, the scintillation light is collected and transported by WLS optical fibers, while light detection is performed by pairs of avalanche photodiodes with the Metal-Resistor-Semiconductor structure operated in the Geiger mode (MRS APD). START delivers 100% efficiency of cosmic muon detection, while its intrinsic noise level is less than 10^{-2} Hz. CRTF, consisting of 160 START channels, has been continuously operated by the ALICE TOF collaboration for more than 25 000 hours, and has demonstrated a high level of stability. Fewer than 10% of MRS APDs had to be replaced during this period.Comment: Proceedings of NDIP-2008. 8 pages, 8 figures, 6 reference

Lyotropic chromonic liquid crystal semiconductors for water-solution processable organic electronics

We propose lyotropic chromonic liquid crystals (LCLCs) as a distinct class of materials for organic electronics. In water, the chromonic molecules stack on top of each other into elongated aggregates that form orientationally ordered phases. The aligned aggregated structure is preserved when the material is deposited onto a substrate and dried. The dried LCLC films show a strongly anisotropic electric conductivity of semiconductor type. The field-effect carrier mobility measured along the molecular aggregates in unoptimized films of LCLC V20 is 0.03 cm^2 V^(-1) s^(-1). Easy processibility, low cost, and high mobility demonstrate the potential of LCLCs for microelectronic applications

Scintillation counter with MRS APD light readout

START, a high-efficiency and low-noise scintillation detector for ionizing particles, was developed for the purpose of creating a high-granular system for triggering cosmic muons. Scintillation light in START is detected by MRS APDs (Avalanche Photo-Diodes with Metal-Resistance-Semiconductor structure), operated in the Geiger mode, which have 1 mm^2 sensitive areas. START is assembled from a 15 x 15 x 1 cm^3 scintillating plastic plate, two MRS APDs and two pieces of wavelength-shifting optical fiber stacked in circular coils inside the plastic. The front-end electronic card is mounted directly on the detector. Tests with START have confirmed its operational consistency, over 99% efficiency of MIP registration and good homogeneity. START demonstrates a low intrinsic noise of about 10^{-2} Hz. If these detectors are to be mass-produced, the cost of a mosaic array of STARTs is estimated at a moderate level of 2-3 kUSD/m^2.Comment: 6 pages, 5 figure

START as the detector of choice for large-scale muon triggering systems

Further progress in building high-granular large-scale systems based on Scintillation Tiles with MRS APD light readout (START) became possible thanks to the creation of an improved version of MRS APD. The cost of the system may now be significantly reduced by using inexpensive extruded scintillator. More than 160 START samples were assembled based on this design modification and proved to possess 100% MIP detection efficiency and the intrinsic noise rate of less than 0.08 Hz. Long-term stability of START characteristics was confirmed after 3.5 months of operation

Magnetic liposome design for drug release systems responsive to super-low frequency alternating current magnetic field (AC MF)

HYPOTHESIS: Magnetic liposomes are shown to release the entrapped dye once modulated by low frequency AC MF. The mechanism and effectiveness of MF application should depend on lipid composition, magnetic nanoparticles (MNPs) properties, temperature and field parameters. EXPERIMENTS: The study was performed using liposomes of various lipid composition and embedded hydrophobic MNPs. The liposomes structural changes were studied by the transmission electron microscopy (TEM) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and the leakage was monitored by the fluorescent dye release. FINDINGS: Magnetic liposomes exposure to the AC MF resulted in the clustering of the MNPs in the membranes and disruption of the lipid packaging. Addition of cholesterol diminished the dye release from the saturated lipid-based liposomes. Replacement of the saturated lipid for unsaturated one also decreased the dye release. The dye release depended on the strength, but not the frequency of the field. Thus, the oscillating motion of MNPs in AC MF ruptures the gel phase membranes of saturated lipids. As the temperature increases the disruption also increases. In the liquid crystalline membranes formed by unsaturated lipids the deformations and defects created by mechanical motion of the MNPs are more likely to heal and results in decreased release

Measurement of the two-photon exchange contribution in elastic epep scattering at VEPP-3

We report on the status of the Novosibirsk experiment on a precision measurement of the ratio $R$ of the elastic $e^+ p$ and $e^- p$ scattering cross sections. Such measurements determine the two-photon exchange effect in elastic electron-proton scattering. The experiment is conducted at the VEPP-3 storage ring using a hydrogen internal gas target. The ratio $R$ is measured with a beam energy of 1.6 GeV (electron/positron scattering angles are $\theta = 55 \div 75^{\circ}$ and $\theta = 15 \div 25^{\circ}$) and 1 GeV ($\theta = 65 \div 105^{\circ}$). We briefly describe the experimental method, paying special attention to the radiative corrections. Some preliminary results are presented.Comment: 5 pages, 6 figures and 1 table; contribution to the Proceedings of the PHIPSI11 Workshop (Novosibirsk, Russia, 19-22 September 2011

Development of recombinant adeno-associated virus empty capsids as a reference standard for quality control of gene therapy products

INTRODUCTION. The development of adeno-associated virus (AAV)-based gene therapy products in Russia requires establishing reference standards, which are used throughout the pharmaceutical development cycle, and monitoring their stability during the storage period. A preparation of empty capsids of AAV serotype 9 (AAV9) is an appropriate material for a reference standard for empty AAV9 capsids (AAV9 RS).AIM. This study aimed to develop analytical procedures to evaluate the AAV9 RS physicochemical quality parameters for its characterisation and to study its storage stability.MATERIALS AND METHODS. Empty AAV9 capsids were produced in HEK293 suspension culture using serum-free medium and optimised transfection parameters. The next steps involved AAV9 clarification, concentration, and purification by affinity chromatography with AAVx resin and diafiltration. The analysis of AAV9 samples used electrophoresis, transmission electron microscopy, enzyme-linked immunosorbent assay (ELISA), size-exclusion chromatography, dynamic light scattering, spectrophotometry, and bio-layer interferometry. The concentration of capsids was measured by ELISA. Analytical procedures for physical titre determination were developed using an AAV9 standard with a known physical titre. The stability study of the AAV9 RS involved storage at –80 °C for 9 months.RESULTS. Size-exclusion chromatography demonstrated the high purity of the established AAV9 RS, with at least 98% content of the viral capsid monomer. Dynamic light scattering, size-exclusion chromatography, and electron microscopy confirmed that the AAV9 RS was free of aggregates. The stability study showed that the AAV9 RS remained stable for 9 months. Dynamic light scattering and spectrophotometry were deemed optimal methods for routine quality analysis measuring the AAV9 RS physical titre, and bio-layer interferometry was recommended for regular analysis. The viral particle titres determined by these methods ranged from 1.48×1013 to 5.6×1013.CONCLUSIONS. The AAV9 RS established in this study is suitable for quality control of AAV9-based gene therapy products

Measurement of ZZ production in leptonic final states at {\surd}s of 1.96 TeV at CDF

In this paper we present a precise measurement of the total ZZ production cross section in pp collisions at {\surd}s= 1.96 TeV, using data collected with the CDF II detector corresponding to an integrated luminosity of approximately 6 fb-1. The result is obtained by combining separate measurements in the four-charged (lll'l'), and two-charged-lepton and two-neutral-lepton (llvv) decay modes of the Z. The combined measured cross section for pp {\to} ZZ is 1.64^(+0.44)_(-0.38) pb. This is the most precise measurement of the ZZ production cross section in 1.96 TeV pp collisions to date.Comment: submitted to Phys. Rev. Let