208 research outputs found

    Thermoactive cellulase-free xylanase production from alkaliphilic Bacillus strains using various agro-residues and their potential in biobleaching of kraft pulp

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    The four bacterial strains were isolated on media containing xylan and screened for xylanase activity. The bacterial strains (Ag12, Ag13, Ag20 and Ag32) were characterized based on morphological, biochemical and physiological characters and identified as belonging to the genus Bacillus. The effects of different factors such as pH (7.0 – 10.0), temperature (25.0 – 50.0°C) and inexpensive agro-residues (wheat straw, wheat bran and corncob) on xylanase production of strains were studied under shakeflask conditions. Maximal enzyme activities were obtained by cultivation in birch-wood xylan, but high enzyme production was also obtained on wheat straw and corncob when cultivated at pH 8.5. Under optimized fermentation conditions, no cellulolytic activity were detected on the crude extracts. Theeffects of temperature (40.0 – 80.0°C), pH (6.0 – 10.0) and salt concentration (1.0, 5.0 and 10.0%) on the xylanases activity were determined. The maximum activity was obtained temperature 60.0°C and pH at 9.0. The enzyme was stable at 60.0°C for more than 60 min, suggesting that the xylanases of Bacillus strains are thermoactive and being of interests for biobleaching processes. The effectiveness of crudexylanases from the strains Ag12, Ag20 and Ag32 on kraft pulp were carried out at pH 9.0 at 60.0°C. Biobleaching studies of kraft pulp with xylanases and its subsequent treatment with 1.0% EDTA (30 min at 50.0°C) and peroxide (80 min at 70.0°C), showed that the enzymes reduced the kappa number by 27.4, 61.7 and 75.3% and enhanced the brightness by 1.0, 1.5 and 3.0% from xylanases produced by strains Ag12, Ag20 and Ag32, respectively. These results suggest that the application of this xylanases to the paper and pulp industry may be very promising

    Precision spectroscopy with two correlated atoms

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    We discuss techniques that allow for long coherence times in laser spectroscopy experiments with two trapped ions. We show that for this purpose not only entangled ions prepared in decoherence-free subspaces can be used but also a pair of ions that are not entangled but subject to the same kind of phase noise. We apply this technique to a measurement of the electric quadrupole moment of the 3d D5/2 state of 40Ca+ and to a measurement of the linewidth of an ultrastable laser exciting a pair of 40Ca+ ions

    Distribution and genetic diversity of Dothistroma septosporum in Pinus brutia forests of south-western Turkey

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    The support of the DIAROD project, funded as EU COST Action FP1102, is gratefully acknowledged. Forest engineers Ali Datumani and Erdal Örtel are thanked for their great help in the field. We are grateful to the anonymous reviewers who helped improve the manuscript. We would like to thank Dr Alkan Unlu for providing the climate data and to Dr Ilker Ercanli for performing the statistical analysis. The study was financially supported by the Forestry Commission, United Kingdom and by the European Regional Development Fund, Project Phytophthora Research Centre Reg. No. CZ.02.1.01/0.0/0.0/15_003/0000453.Peer reviewedPostprin

    Assesment of hypertension knowledge, attitude and throught of policyclinic patients at a primary health care center in İzmir

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    OBJECTIVE: Hypertension is an important public health problem with high prevelance. The aim of our study is to assess the knowledge, opinion and approach of polyclinic patients to hypertension at a primary health care center in Izmir. MATERIALS and METHODS: This descriptive study was performed in a primary health care center in Izmir with 245 participants attending to this primary health care center during September 2006. Study data was collected by a two part questionnaire, using face to face interview. The data was evaluated by descriptive statatistics, chi square and Fisher exact tests. Logistic regression analysis was performed to determine the factors effecting the knowledge on hypertension and p<0.05 was accepted significant. RESULTS: The mean age of the participants was 49.32±16.84 and %62 of them were women, %49 were primary school graduates and %75.5 of them were with low socioeconomic level. %12.7 of the participants knew the hypertension levels correctly and %19.6 of them had their blood pressure measured when they attented to a clinic because of a problem. There was a significant difference between hypertension awareness level and socioeconomic level (p<0.05). Socioeconomic level was found as an effecting factor on hypertension awareness level by logistic regression analysis. CONCLUSION: We found the knowledge levels of the participants at a low level. Effective, acceptible and applicable community based protection and education projects should be performed about hypertension which is an important public health problem in the region. By this way the knowledge and awareness of society about hypertension will be raised and attitude and behaviour changes will be able to be realized.OBJECTIVE: AMAÇ: Hipertansiyon yüksek prevalansı ile önemli bir halk saglıgı sorundur.Arastırmamızın amacı Izmir'de bir saglık ocagına basvuran poliklinik hastalarının hipertansiyon hakkındaki bilgi, tutum ve görüslerinin degerlendirilmesidir. GEREÇ ve YÖNTEM: Tanımlayıcı tipteki bu arastırma Eylül 2006 tarihinde Izmir Ballıkuyu Saglık Ocagı'na basvuran ve arastırmaya katılmayı kabul eden 245 kisiyle yürütüldü. Arastırmanın verileri iki bölümden olusan anket formunun yüzyüze görüsme teknigi ile uygulanması yoluyla toplandı. Verilerin istatistik analizlerinde tanımlayıcı istatistikler, ki-kare ve Fisher'in kesin testi kullanıldı. Hipertansiyon bilgi düzeyine etki eden faktörlerin degerlendirilmesinde lojistik regresyon analizi kullanıldı ve p<0.05 istatistiksel anlamlılık düzeyi olarak kabul edildi. BULGULAR: Katılımcıların yas ortalaması 49.32±16.84 idi ve %62'si kadın, %49'u ilkokul mezunu ve %75.5'i alt sosyoekonomik düzeyde idi. Katılımcıların %12.72si kan basıncı degerlerini dogru olarak bilmisti. Katılımcıların %19.6'sı herhangi bir nedenle doktora gittiklerinde tansiyonlarını ölçtürdüklerini belirtmisti. Katılımcıların kan basıncı degerleri bilgi durumları ile sosyoekonomik düzey arasında anlamlı farklılık bulundu (p<0.005)). Lojistik regresyon sonucunda da sosyoekonomik düzeyin hipertansiyonla ilgili bilgi düzeyini etkiledigi belirlendi. SONUÇ: Arastırmamıza katılanların hipertansiyonla ilgili bilgi düzeyleri düsük bulunmustur. Bölgede önemli bir halk saglıgı problemi olan hipertansiyon konusunda etkin, toplumca kabul görmüs ve uygulanabilir toplum tabanlı koruma ve egitim projeleri uygulanmalıdır. Bu sekilde toplumun hipertansiyon konusundaki bilgi ve farkındalıkları arttırılarak tutum ve davranıs degisiklikleri gerçeklesebilecektir

    Diffusion Resonances in Action Space for an Atom Optics Kicked Rotor with Decoherence

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    We numerically investigate momentum diffusion rates for the pulse kicked rotor across the quantum to classical transition as the dynamics are made more macroscopic by increasing the total system action. For initial and late time rates we observe an enhanced diffusion peak which shifts and scales with changing kick strength, and we also observe distinctive peaks around quantum resonances. Our investigations take place in the context of a system of ultracold atoms which is coupled to its environment via spontaneous emission decoherence, and the effects should be realisable in ongoing experiments.Comment: 4 Pages, RevTeX 4, 5 Figures. Updated Figures, Minor Changes to text, Corrected Reference

    Quantum control, quantum information processing, and quantum-limited metrology with trapped ions

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    We briefly discuss recent experiments on quantum information processing using trapped ions at NIST. A central theme of this work has been to increase our capabilities in terms of quantum computing protocols, but we have also applied the same concepts to improved metrology, particularly in the area of frequency standards and atomic clocks. Such work may eventually shed light on more fundamental issues, such as the quantum measurement problem.Comment: Proceedings of the International Conference on Laser Spectroscopy (ICOLS), 10 pages, 5 figure

    'Designer atoms' for quantum metrology

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    Entanglement is recognized as a key resource for quantum computation and quantum cryptography. For quantum metrology, the use of entangled states has been discussed and demonstrated as a means of improving the signal-to-noise ratio. In addition, entangled states have been used in experiments for efficient quantum state detection and for the measurement of scattering lengths. In quantum information processing, manipulation of individual quantum bits allows for the tailored design of specific states that are insensitive to the detrimental influences of an environment. Such 'decoherence-free subspaces' protect quantum information and yield significantly enhanced coherence times. Here we use a decoherence-free subspace with specifically designed entangled states to demonstrate precision spectroscopy of a pair of trapped Ca+ ions; we obtain the electric quadrupole moment, which is of use for frequency standard applications. We find that entangled states are not only useful for enhancing the signal-to-noise ratio in frequency measurements - a suitably designed pair of atoms also allows clock measurements in the presence of strong technical noise. Our technique makes explicit use of non-locality as an entanglement property and provides an approach for 'designed' quantum metrology

    Squeezing of Atoms in a Pulsed Optical Lattice

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    We study the process of squeezing of an ensemble of cold atoms in a pulsed optical lattice. The problem is treated both classically and quantum-mechanically under various thermal conditions. We show that a dramatic compression of the atomic density near the minima of the optical potential can be achieved with a proper pulsing of the lattice. Several strategies leading to the enhanced atomic squeezing are suggested, compared and optimized.Comment: Latex, 9 pages, 10 figures, submitted to PR

    Testing the stability of fundamental constants with the 199Hg+ single-ion optical clock

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    Over a two-year duration, we have compared the frequency of the 199Hg+ 5d106s 2S 1/2 (F=0) 5d9 6s2 2D 5/2 (F=2) electric-quadrupole transition at 282 nm with the frequency of the ground-state hyperfine splitting in neutral 133Cs. These measurements show that any fractional time variation of the ratio nu(Cs)/nu(Hg) between the two frequencies is smaller than +/- 7 10^-15 / yr (1 sigma uncertainty). According to recent atomic structure calculations, this sets an upper limit to a possible fractional time variation of g(Cs) m_e / m_p alpha^6.0 at the same level.Comment: 4 pages with 3 figures. RevTeX 4, Submitted to Phys. Rev. Let
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