Low-Temperature Operation of AlFaN Single-Quantum-Well Light-Emitting Diodes with Deep Ultraviolet Emission at 285 nm

We present a study of the electrical and optical characteristics of 285 nm emission deep ultraviolet light-emitting diodes(LED) at temperatures from 10 to 300 K. At low bias, our data show the tunneling carrier transport to be the dominant conduction mechanism. The room-temperature performance is shown to be limited mostly by poor electron confinement in the active region and a pronounced deep level assisted recombination but not by the hole injection into the active region. At temperatures below 100 K, the electroluminescence peak intensity increases by more than one order of magnitude indicating that with a proper device design and improved material quality, milliwatt power 285 nm LED are viable

Ultraviolet Light-Emitting Diodes at 340 nm using Quaternary AlInGaN Multiple Quantum Wells

An ultraviolet light-emitting diode with peak emission wavelength at 340 nm is reported. The active layers of the device were comprised of quaternary AlInGaN/AlInGaN multiple quantum wells, which were deposited over sapphire substrates using a pulsed atomic-layer epitaxy process that allows precise control of the composition and thickness. A comparative study of devices over sapphire and SiC substrates was done to determine the influence of the epilayer design on the performance parameters and the role of substrate absorption

Генератор чистого водорода

Тhe results of works about the creation of hydrogen generator on the basis of solid polymeric electrolyte was given.Представлены результаты проведенных работ по созданию генератора водорода на основе применения твердополимерного электролита

Extraction of tannin, gallic acid and pyrogallol from aqueous media with water-soluble polymers and their determination in concentrates by thin-layer chromatography

Для экстракции танина, галловой кислоты и пирогаллола из водно-солевых растворов впервые применены водорастворимые гомо- и сополимеры на основе N-винилкапролактама и N-винилпирролидона. Установлены коэффициенты распределения и степень извлечения фенолов. Экстракционные характеристики фенолов зависят от их растворимости, строения, числа функциональных групп в их молекулах, способных образовывать водородные связи и π-комплексы с полимерами. Большие коэффициенты распределения таннина обусловлены его высокой гидрофобностью. Установлено, что сополимер N-винилпирролидона и N-винилкапролактама проявляет большую экстракционную способность по сравнению с гомополимерами. Эффективность экстракции исследуемых фенолов зависит от рН раствора. Максимальная степень извлечения фенолов достигается при рН = 3. Обоснованы условия разделения и определения фенолов в полимерно-водном концентрате методом хроматографии в тонком слое. Селективное разделение исследуемых фенолов проводили с применением подвижной фазы, состоящей из бутанола-1, уксусной кислоты и хлороформа в соотношении (об.) 4 : 1 : 5. Элюент исключает размывание пятен. По сравнению с известными хроматографическими системами время разделения аналитов уменьшается с 60 до 20-30 минут. Установлено, что природа полимера и его присутствие в концентрате не влияет на хроматографические характеристики. Разработан способ определения исследуемых веществ в водных средах.For the first time water-soluble homo- and co-polymers based on N-vinylcaprolactam and N-vinylpyrrolidone were applied for the extraction of tannin, gallic acid and pyrogallol from the aqueous-salt solutions. The distribution coefficients and the degree of extraction of phenols were established. Extraction characteristics of phenols depend on their solubility, structure, and the number of functional groups in their molecules that can form hydrogen bonds and π-complexes with polymers. The large distribution coefficients of tannin are due to its high hydrophobicity. It was established that the copolymer of N-vinylpyrrolidone with N-vinylcaprolactam shows higher extraction efficiency than homopolymers. The efficiency of extraction of the studied phenols depends on the pH of aqueous solutions. The maximum degree of extraction of phenols was achieved at pH 3. Conditions of division and determination of phenols in the polymer-aqueous concentrate using the chromatography method in a thin layer were chosen. It has been established that the selective separation of the investigated phenols is achieved using a mobile phase of 1-butanol, acetic acid and chloroform in the ratio (vol.) 4 : 1 : 5. Eluent eliminates the blur spots. Separation time of analytes is reduced from 60 to 20-30 min in comparison with known chromatographic systems. It was established that the nature of the polymer and its presence in the concentrate does not affect the chromatographic characteristics. The technique of determination of studied substances in aqueous media was developed

EXTRACTION OF TANNIN, GALLIC ACID AND PYROGALLOL FROM AQUEOUS MEDIA WITH WATER-SOLUBLE POLYMERS AND THEIR DETERMINATION IN CONCENTRATES BY THIN-LAYER CHROMATOGRAPHY

For the first time water-soluble homo- and co-polymers based on N-vinylcaprolactam and N-vinylpyrrolidone were applied for the extraction of tannin, gallic acid and pyrogallol from the aqueous-salt solutions. The distribution coefficients and the degree of extraction of phenols were established. Extraction characteristics of phenols depend on their solubility, structure, and the number of functional groups in their molecules that can form hydrogen bonds and π-complexes with polymers. The large distribution coefficients of tannin are due to its high hydrophobicity. It was established that the copolymer of N-vinylpyrrolidone with N-vinylcaprolactam shows higher extraction efficiency than homopolymers. The efficiency of extraction of the studied phenols depends on the pH of aqueous solutions. The maximum degree of extraction of phenols was achieved at pH 3. Conditions of division and determination of phenols in the polymer-aqueous concentrate using the chromatography method in a thin layer were chosen. It has been established that the selective separation of the investigated phenols is achieved using a mobile phase of 1-butanol, acetic acid and chloroform in the ratio (vol.) 4 : 1 : 5. Eluent eliminates the blur spots.  Separation time of analytes is reduced from 60 to 20-30 min in comparison with known chromatographic systems. It was established that the nature of the polymer and its presence in the concentrate does not affect the chromatographic characteristics. The technique of determination of studied substances in aqueous media was developed.Keywords: polyphenols, tannin, gallic acid, pyrogallol, extraction, chromatography, water-soluble polymers, N-vinylpyrrolidone, N-vinylcaprolactam, copolymer(Russian)DOI: http://dx.doi.org/10.15826/analitika.2015.19.3.005 P.T. Sukhanov1, A.N. Il’yin1, E.V. Churilina1, G.V. Shatalov21Voronezh State University of Engineering Technologies, Voronezh, Russian Federation2Voronezh State University, Voronezh, Russian Federatio

EXTRACTION OF TANNIN, GALLIC ACID AND PYROGALLOL FROM AQUEOUS MEDIA WITH WATER-SOLUBLE POLYMERS AND THEIR DETERMINATION IN CONCENTRATES BY THIN-LAYER CHROMATOGRAPHY

For the first time water-soluble homo- and co-polymers based on N-vinylcaprolactam and N-vinylpyrrolidone were applied for the extraction of tannin, gallic acid and pyrogallol from the aqueous-salt solutions. The distribution coefficients and the degree of extraction of phenols were established. Extraction characteristics of phenols depend on their solubility, structure, and the number of functional groups in their molecules that can form hydrogen bonds and π-complexes with polymers. The large distribution coefficients of tannin are due to its high hydrophobicity. It was established that the copolymer of N-vinylpyrrolidone with N-vinylcaprolactam shows higher extraction efficiency than homopolymers. The efficiency of extraction of the studied phenols depends on the pH of aqueous solutions. The maximum degree of extraction of phenols was achieved at pH 3. Conditions of division and determination of phenols in the polymer-aqueous concentrate using the chromatography method in a thin layer were chosen. It has been established that the selective separation of the investigated phenols is achieved using a mobile phase of 1-butanol, acetic acid and chloroform in the ratio (vol.) 4 : 1 : 5. Eluent eliminates the blur spots.  Separation time of analytes is reduced from 60 to 20-30 min in comparison with known chromatographic systems. It was established that the nature of the polymer and its presence in the concentrate does not affect the chromatographic characteristics. The technique of determination of studied substances in aqueous media was developed.Keywords: polyphenols, tannin, gallic acid, pyrogallol, extraction, chromatography, water-soluble polymers, N-vinylpyrrolidone, N-vinylcaprolactam, copolymer(Russian)DOI: http://dx.doi.org/10.15826/analitika.2015.19.3.005 P.T. Sukhanov1, A.N. Il’yin1, E.V. Churilina1, G.V. Shatalov21Voronezh State University of Engineering Technologies, Voronezh, Russian Federation2Voronezh State University, Voronezh, Russian Federatio

Performance of the LHCb muon system

The performance of the LHCb Muon system and its stability across the full 2010 data taking with LHC running at ps = 7 TeV energy is studied. The optimization of the detector setting and the time calibration performed with the first collisions delivered by LHC is described. Particle rates, measured for the wide range of luminosities and beam operation conditions experienced during the run, are compared with the values expected from simulation. The space and time alignment of the detectors, chamber efficiency, time resolution and cluster size are evaluated. The detector performance is found to be as expected from specifications or better. Notably the overall efficiency is well above the design requirementsComment: JINST_015P_1112 201

Performance of the LHCb muon system with cosmic rays

The LHCb Muon system performance is presented using cosmic ray events collected in 2009. These events allowed to test and optimize the detector configuration before the LHC start. The space and time alignment and the measurement of chamber efficiency, time resolution and cluster size are described in detail. The results are in agreement with the expected detector performance.Comment: Submitted to JINST and accepte

Performance of a spaghetti calorimeter prototype with tungsten absorber and garnet crystal fibres

A spaghetti calorimeter (SPACAL) prototype with scintillating crystal fibres was assembled and tested with electron beams of energy from 1 to 5 GeV. The prototype comprised radiation-hard Cerium-doped GdAlGaO (GAGG:Ce) and YAlO (YAG:Ce) embedded in a pure tungsten absorber. The energy resolution was studied as a function of the incidence angle of the beam and found to be of the order of 10%/E⊕1%, in line with the LHCb Shashlik technology. The time resolution was measured with metal channel dynode photomultipliers placed in contact with the fibres or coupled via a light guide, additionally testing an optical tape to glue the components. Time resolution of a few tens of picosecond was achieved for all the energies reaching down to (18.5 ± 0.2) ps at 5 GeV.We acknowledge support by the CERN Strategic Programme on Technologies for Future Experiments, https://ep-rnd.web.cern.ch/, by the MCIN/AEI, GenCat and GVA (Spain), and by the NSFC (China) under grant Nos. 12175005, 12061141007. The measurements were performed at the Test Beam Facility at DESY Hamburg (Germany), a member of the Helmholtz Association (HGF). The authors would like to thank T. Schneider, H. Gerwig, N. Siegrist, and D. Deyrail (CERN) for their help in designing and assembling the prototype and the set-up, A. Barnyakov, Budker Institute of Nuclear Physics (BINP), Novosibirsk, for kindly providing the MCPs, and the ITEP ATLAS group for the DWCs

Measurement of the ratio of branching fractions BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma)

The ratio of branching fractions of the radiative B decays B0 -> K*0 gamma and Bs0 -> phi gamma has been measured using 0.37 fb-1 of pp collisions at a centre of mass energy of sqrt(s) = 7 TeV, collected by the LHCb experiment. The value obtained is BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma) = 1.12 +/- 0.08 ^{+0.06}_{-0.04} ^{+0.09}_{-0.08}, where the first uncertainty is statistical, the second systematic and the third is associated to the ratio of fragmentation fractions fs/fd. Using the world average for BR(B0 -> K*0 gamma) = (4.33 +/- 0.15) x 10^{-5}, the branching fraction BR(Bs0 -> phi gamma) is measured to be (3.9 +/- 0.5) x 10^{-5}, which is the most precise measurement to date.Comment: 15 pages, 1 figure, 2 table