The compensation of the noise due to angular oscillations of the laser beam in the Precision Laser Inclinometer

An experimental method for the compensation of the noise originated by the laser ray angular oscillations was proposed and experimentally proved for the Precision Laser Inclinometer (PLI). The PLI noise spectral density was reduced by factor 30× and reached 10^–8 rad/Hz^1/2 level at the frequency of 5 × 10^–5 Hz. The angular noise of a laser ray leaving the one-mode optical fiber in the vacuum and in stabilized temperature conditions has been measured. The amplitude of the oscillations for one-day observation reached 0.46 μrad.     

The temperature stability of 0.005°C for the concrete floor in the CERN Transfer Tunnel #1 hosting the Precision Laser Inclinometer

To reach a sensitivity level of ~10^–9 rad for the Precision Laser Inclinometer (PLI) for the registration of the Earth surface angular oscillation in the low frequency band of [10^–6 Hz; 1 Hz] the temperature stability of the CERN Transfer Tunnel #1 has been investigated. The daily temperature variation was 0.082°C for the air and 0.005°C for the concrete floor. The last result opened the possibility to observe the Earth surface inclination caused by Moon and Sun if the PLI is thermally stabilized by the massive monolithic concrete floor of the tunnel.     

Measurement of small angle based on a (1 0 0) silicon wafer and heterodyne interferometer

In this paper, a new optical material application and a heterodyne interferometer are proposed for measuring small angles. In the proposed interferometer, the optical material is a (1 0 0) silicon wafer applied to compose a new architecture of small angle sensor. The small angle measurement used the phase difference which is dependent on the incident angle at the silicon wafer surface to deduce the angular variation. The proposed architecture is simple and uses the common path method to compare test and reference signals; thus, small angles can be easily and accurately measured by estimating the phase difference. The experimental results demonstrate the feasibility of this method. The angular resolution and sensitivity levels superior to 7 × 10^?5° (1.3 × 10^?6 rad) and 150 (deg/deg), respectively, were attainable in a dynamic range of 0.45°.     

Rotation of neutron spin in passing through a noncentrosymmetric single crystal

Rotation of the spin of cold neutrons passing through a noncentrosymmetric single crystal is observed. This effect is caused by the Schwinger interaction of the magnetic moment of a moving neutron with the crystalline electric field in a noncentrosymmetric single crystal and depends both on the direction of neutron trajectory in the crystal and on its energy. It is shown that the characteristic magnitude of the effect for α-quartz is ?(1–2)×10^?4 rad/cm over a wide wavelength range (from 2.8 to 5.5 Å) and is determined by the degree of beam monochromaticity [Δλ/λ=(2–5)×10^?2 in our experiment]. This magnitude corresponds to an electric field of ?(0.5–1)×10⁵ V/cm acting on a neutron. The measured value agrees well with the theoretical calculation.     

Spectral calibration of filters and detectors of solar telescope at a wavelength of 13.2 nm for the TESIS project

The telescope at a wavelength of 13.2 nm of the TESIS device of the CORONAS-PHOTON satellite is intended for imaging hot plasma (T ～ 10 MK) of the solar corona. In this paper, calibration of optical elements of the telescope is described. The transmittance of multilayer Zr/Si filters and the sensitivity and radiation resistance of the CCD-array-based detector were measured. The transmittance of filters in the operating wavelength range was 40–50% (for filters of various thicknesses); the spectral dependence of the transmittance was close to the calculated one. The transmittance of filters in the visible region was (1–2) × 10^?6. The detector sensitivity was 0.01–0.1 analog-to-digital units per photon (adu/photon), the radiation resistance was better than 10⁹ rad.     

A calix[4]arene derivative-doped perchlorate-selective membrane electrodes with/without multi-walled carbon nanotubes

In this study, poly (vinyl chloride)(PVC) membrane electrodes with/without multi-walled carbon nanotubes (MWCNTs) based on a calix[4]arene derivative for perchlorate ion were described. The influence of membrane composition, pH, conditioning solution on the potentiometric response of the electrodes was investigated. Perchlorate-selective PVC membrane electrode exhibited a slope of 47.8 ± 0.6 mV/pClO₄ in the range of 1.0 × 10^?7–1.0 × 10^?1 mol L^?1at pH 4.0 while the coated Pt electrodes with MWCNT-OH, MWCNT-COOH and MWCNT displayed slopes of 46.1 ± 0.7 mV/pClO₄ (5.0 × 10^?6–1.0 × 10^?1 mol L^?1), 50.4 ± 1.9 mV/pClO₄ (1.0 × 10^?6–1.0 × 10^?1 mol L^?1) and 44.4 ± 0.3 mV/pClO₄ (1.0 × 10^?5–1.0 × 10^?1 mol L^?1), respectively. Other response characteristics of these electrodes such as response time, lifetime and detection limit were identified, and the selectivity coefficients towards various anions were calculated by separate solution method. Moreover, the perchlorate-selective electrodes described here were successfully used as an indicator electrode for the determination of perchlorate in real samples such as tap water, river water and human urine by direct calibration method.     

A laser sensor of a seismic slope of the Earth surface

A principally new method of the measurement of a seismic slope of the Earth surface is suggested. The method makes it possible to stabilize the position of the laser beam as a highly extended coordinate axis in the metrological support of the precision construction of large-scale physical installations. The method has been tested experimentally: for the first time, low-frequency periodic angular oscillations have been registered with an amplitude of 5 × 10^?7 rad and the noise registration value of 2.5 × 10^?8 rad. The measurements were taken at CERN, during the construction of the spectrometric complex ATLAS.     

Focusing,collimation and flux throughput at the IMCA‐CAT bending‐magnet beamline at the Advanced Photon Source

The IMCA‐CAT bending‐magnet beamline was upgraded with a collimating mirror in order to achieve the energy resolution required to conduct high‐quality multi‐ and single‐wavelength anomalous diffraction (MAD/SAD) experiments without sacrificing beamline flux throughput. Following the upgrade, the bending‐magnet beamline achieves a flux of 8 × 10¹¹ photons s^?1 at 1 Å wavelength, at a beamline aperture of 1.5 mrad (horizontal) × 86 µrad (vertical), with energy resolution (limited mostly by the intrinsic resolution of the monochromator optics) δE/E = 1.5 × 10^?4 (at 10 kV). The beamline operates in a dynamic range of 7.5–17.5 keV and delivers to the sample focused beam of size (FWHM) 240 µm (horizontally) × 160 µm (vertically). The performance of the 17‐BM beamline optics and its deviation from ideally shaped optics is evaluated in the context of the requirements imposed by the needs of protein crystallography experiments. An assessment of flux losses is given in relation to the (geometric) properties of major beamline components.     

The GaP(001) surface and the adsorption of Cs

GaP(001) cleaned by argon-ion bombardment and annealed at 500°C showed the Ga-stabilized GaP(001)(4 × 2) structure. Only treatment in 10^?5 Torr PH₃ at 500°C gave the P-stabilized GaP(001)(1 × 2) structure. The AES peak ratio $\text{P}\text{Ga}$ is 2 for the (4 × 2) and 3.5 for the (1 × 2) structure. Cs adsorbs with a sticking probability of unity up to 5 × 10¹⁴ Cs atoms cm^?2 and a lower one at higher coverages. The photoemission measured with uv light of 3660 Å showed a maximum at the coverage of 5 × 10¹⁴ atoms cm^?2. Cs adsorbs amorphously at room temperature, but heat treatment gives ordered structures, which are thought to be reconstructed GaP(001) structures induced by Cs. The LEED patterns showed the GaP(001)(1 × 2) Cs structure formed at 180°C for 10 h with a Cs coverage of 5 × 10¹⁴ atoms cm^?2, the GaP(001)(1 × 4) Cs formed at 210°C for 10 hours with a Cs coverage of 2.7 × 10¹⁴ atoms cm^?2, the GaP(001)(7 × 1) and the high temperature GaP(001)(1 × 4), the latter two with very low Cs content. Desorption measurements show three stability regions: (a) between 25–150°C for coverages greater than 5 × 10¹⁴ atoms cm^?2, and an activation energy of 1.2 eV; (b) between 180–200°C with a coverage of 5 × 10¹⁴ atoms cm^?2, and an activation energy of 1.8 eV; (c) between 210–400°C with a coverage of 2.7 × 10¹⁴ atoms cm^?2, and an activation energy of 2.5 eV.     

AES-LEED-ellipsometry study of the kinetics of the interaction of methane with Ni(110)

The interaction of methane with Ni(110) was studied with AES, LEED and ellipsometry. Sticking coefficients were determined in the temperature range 298–600 K at methane pressures of 10^?4–10^?2 Torr. The carbon coverages were derived from Auger spectra by calibration with ellipsometry. At room temperature no detectable adsorption was observed without use of electron sources. In the temperature range 473–579 K the coverage versus exposure curves show an induction effect at low coverage followed by an almost linear increase up to a saturation coverage of about $\text{1}\text{3}$ monolayer of carbon. At these temperatures a Ni(110)-(2 × 3)-C structure was observed with streaks in the direction of constant h. The observed behaviour is explained with a nucleation and growth model in which mobile carbon species are captured at the edges of surface nickel carbide islands. At temperatures above 600 K carbon diffuses into the bulk and the Ni(110)-(4 × 5)-C superstructure is observed.     

Surface-enhanced Raman scattering study of carcinoembryonic antigen in serum from patients with colorectal cancers

In this work, we developed a SERS platform for quantitative detection of carcinoembryonic antigen (CEA) in serum of patients with colorectal cancers. Anti-CEA-functionalized 4-mercaptobenzoic acid–labeled Au/Ag core-shell bimetallic nanoparticles were prepared first and then used to analyze CEA antigen solutions of different concentrations. A calibration curve was established in the range from 5 × 10^?3 to 5 × 10⁵ ng/mL. Finally, this new SERS probe was applied for quantitative detection of CEA in serum obtained from 26 colorectal cancer patients according to the calibration curve. The results were in good agreement with that obtained by electrochemical luminescence method, suggesting that SERS immunoassay has high sensitivity and specificity for CEA detection in serum. A detection limit of 5 pg/ml was achieved. This study demonstrated the feasibility and great potential for developing this new technology into a clinical tool for analysis of tumor markers in the blood.     

Electrochemical methods for determination of thymine in medical pipefish samples based on HPMαFP/Ppy/GCE-modified electrode

A sensitive electrochemical method was developed for the voltammetric determination of thymine at a composite film-modified electrode 1-phenyl-3-methyl-4-(2-furoyl)-5-pyrazolone (HPMαFP)/polypyrrole (Ppy)/glassy carbon electrode (GCE). The electrochemical parameters of thymine were investigated by cyclic voltammetry and differential pulse voltammetry. In pH?=?7.4, one sensitive oxidation peak of thymine with E _pa?=?0.968 V was observed on the HPMαFP/PPy-modified electrode. The difference of peak potential (?E _pa) was 188 mV lower than that for bare GCE. Compared to the bare GCE and Ppy/GCE, the HPMαFP/Ppy/GCE-modified electrode showed an excellent electrocatalytic effect on the oxidation of thymine and displayed a shift of the oxidation potential in the negative direction with significant increase in the peak current. Under the optimum condition, the concentration calibration range and detection limit are 2?×?10^?6–1?×?10^?4 and 4.85?×?10^?7?M for thymine. This developed method had been applied to the direct determination of thymine in medical pipefish samples with satisfactory results.     

Application of fibre-optic rotational seismometer in investigation of seismic rotational waves

Application of a fibre-optic Sagnac interferometer as a rotational seismometer is presented in this paper. It is a new device which parameters (sensitivity equal to 4.3×10⁻⁸ rad/s for 2σ) are comparable with the parameters of typical mechanical rotational seismometers. However, a direct measurement of rotation without influence of linear motions for fibre-optic rotational seismometer designed it for a direct measurement of a ground rotation component. Experimental data obtained during simultaneous application of the above two types of sensors are also presented. Research of near-field seismic events, the amplitude of which has been identified in the range of 1.5×10⁻⁶ rad/s to 2×10⁻⁷ rad/s, shows directly that, so-called, seismic rotational waves exist independently of typical seismic waves generated during earthquakes.     

Fabrication of 6,13‐bis(triisopropyl‐silylethynyl)–pentacene thin‐film transistors with the silver ink transfer method using a polymer stamp

We fabricated 6,13‐bis(triisopropylsilylethynyl)–pentacene (TIPS–pentacene) thin film transistors using a direct metal transfer method. Using different metals, such as Au and Ag ink, electrode patterns are formed from the relief region of the polymer mold. TIPS–pentacene TFTs using the Ag ink transfer method show a similar performance to those using the Au metal transfer method. This method has advantages over the Au metal transfer method because it does not require vacuum equipment and a dry etching process. The self‐assembled monolayer (SAM) treated device exhibits a carrier mobility of 9.5 × 10^–2 cm²/V · s, and an on/off ratio of 4.6 × 10⁴. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Determination of nitrofurans in feeds based on silver nanoparticle-catalyzed chemiluminescence

A highly sensitive chemiluminescence (CL) method for the determination of nitrofurans (NFs) was developed based on the enhancement of CL intensity of luminol–H₂O₂–NFs system by silver nanoparticles (AgNPs). It was supposed that the oxygen-related radicals of OH and superoxide radical (O₂^?) could be produced when NFs reacted with H₂O₂. Furthermore, the enhancement mechanism was originated from the reinforcer of AgNPs, which could catalyze the generation of the OH radical. Then OH radicals reacted with luminol anion and HO₂^? to form luminol radical (L^?) and O₂^?. The excited state 3-aminophthalate anion was obtained in the reaction of L^? and O₂^?, which was the emitter (luminophor) in the luminol–H₂O₂ CL reaction system and the maximal emission of the CL spectrum was at 425 nm. The experiments of scavenging oxygen-related radicals were done to confirm these reactive oxygen species participated in the CL reaction. The limits of detection (LOD) (S/N=3) were 8×10^?7 g mL^?1 for furacilin, 8×10^?8 g mL^?1 for furantoin, 4×10^?8 g mL^?1 for furazolidone and 2×10^?7 g mL^?1 for furaltadone. The proposed method was successfully applied to the determination of NFs in feeds and pharmaceutical samples.     

A novel inverse numerical modeling method for the estimation of water and salt mass transfer coefficients during ultrasonic assisted-osmotic dehydration of cucumber cubes

The objective of this paper was to study the moisture and salt diffusivity during ultrasonic assisted-osmotic dehydration of cucumbers. Experimental measurements of moisture and salt concentration versus time were carried out and an inverse numerical method was performed by coupling a CFD package (OpenFOAM) with a parameter estimation software (DAKOTA) to determine mass transfer coefficients. A good agreement between experimental and numerical results was observed. Mass transfer coefficients were from 3.5 × 10⁻⁹ to 7 × 10⁻⁹ m/s for water and from 4.8 × 10⁻⁹ m/s to 7.4 × 10⁻⁹ m/s for salt at different conditions (diffusion coefficients of around 3.5 × 10⁻¹²–11.5 × 10⁻¹² m²/s for water and 5 × 10⁻¹² m/s–12 × 10⁻¹² m²/s for salt). Ultrasound irradiation could increase the mass transfer coefficient. The values obtained by this method were closer to the actual data. The inverse simulation method can be an accurate technique to study the mass transfer phenomena during food processing.     

Measuring fluence of fast neutrons with planar silicon detectors

The results of measurements of 1-MeV (Si) equivalent fast neutron fluence with silicon planar detectors are reported. The measurement method is based on the linear dependence of the reverse detector current increment on the neutron fluence: ΔI = α _I × Φ × V. This technique provides an opportunity to measure the equivalent fluence in a wide dynamic range from 108 to 10¹⁶ cm^–2 with an unknown neutron energy spectrum and without detector calibration. The proposed method was used for monitoring in radiation resistance tests of different detector types at channel no. 3 of IBR-2 and for determining the fluence of fission and leakage neutrons at the KVINTA setup.     

Untersuchung der Polarisationsebene von Photonen nach Compton-Streuung an polarisierten Elektronen

Two polarization phenomena in Compton scattering by polarized electrons were investigated. In the first experiment, the rotation of the polarization plane of photons passing through magnetized iron and gadolinium was measured. This effect arises from a spin dependence of the Compton forward scattering amplitude. For 228 and 333 keV photons and iron absorbers, the observed rotation angles areφ ₀=(3.90±0.57) ×10^?3 rad · cm^?2 and (4.75±0.58)×10^?3 rad · cm^?2, respectively. Secondly, the orientation of the photon polarization plane after scattering of unpolarized photons by polarized electrons was measured. This experiment tests time reversal invariance in quantum electrodynamics. No dependence of the polarization plane on the direction of the electron spin was found within 2×10^?3.     

Relaxation of vibrationally excited reaction products in a crystal lattice

The relaxation of vibrationally excited nitrogen molecules in the matrix of silver azide is studied. The effective rate constants for the interaction of an excited nitrogen molecule with free charge carriers (1.7 × 10^–10 cm³ s–1) and for the generation a hole from the level of the produced defect at the expense of the vibrational energy of the molecule (3 × 10¹⁰ s^–1) are estimated. An associative–dissociative mechanism of the deactivation is proposed, which consists in the capture of an electron onto the level of the produced defect with the subsequent emission of an electron into the conduction band at the expense of the vibrational energy of the excited molecule. The effective rate constants for electron emission from the excited level of a hydrogen-like defect at values of the principal quantum number of 3 and 4 are estimated as 1.8 × 10⁹ and 2.8 × 10⁹ s^–1, respectively. Based on the processes considered, an expression for the probability of chain propagation is obtained.     

Highly Sensitive Fluorescence Optode Based on Polymer Inclusion Membranes for Determination of Al(III) Ions

This paper reports the use of a polymer inclusion membranes (PIMs) for direct determination of Al(III) ions in natural water by using a fluorescence based optode. The best composition of the PIMs consisted of 60 wt.% (m/m) poly (vinyl chloride) (PVC) as the base polymer, 20 wt.% (m/m) triton X-100 as an extractant, 20 wt.% (m/m) dioctyl phthalate (DOP) as plasticizer and morin as the reagent, was used in this study. The inclusion of triton X-100 was used for enhancing the sorption of Al(III) ions from liquid phase into the membrane phase, thus increasing the optode fluorescence intensity. The optimized optode was characterized by a linear calibration curve in the range from 7.41?×?10^?7 to 1.00?×?10^?4 molL^?1 of Al(III), with a detection limit of 5.19?×?10^?7 molL^?1. The response of the optode was 4 min and reproducible results were obtained for eight different membranes demonstrated good membrane stability. The optode was applied to the determination of Al(III) in natural water samples. The result obtained is comparable to atomic absorption spectrometry method.