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1.
Layer BD York A Antonsen TM Varma S Chen YH Leng Y Milchberg HM 《Physical review letters》2007,99(3):035001
We report the development of corrugated "slow-wave" plasma guiding structures with application to quasiphase-matched direct laser acceleration of charged particles and generation of a wide spectrum of electromagnetic radiation. These structures support guided propagation at intensities up to 2 x 10(17) W/cm(2), limited by our current laser energy and side leakage. Hydrogen and argon plasma waveguides up to 1.5 cm in length with corrugation period as short as 35 microm are generated in a cryogenic cluster jet. Experimental data are consistent with simulations showing periodic modulations of the laser pulse intensity. 相似文献
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We applied two-dimensional gel electrophoresis (2-DE) to study the repertoire of tetanus toxoid (TT)-specific antibodies produced after TT immunization in healthy humans and in severe combined immunodeficient mice xenotransplanted with either human peripheral blood leukocytes (PBLe) or with human adult tonsil (hu-ton) pieces. Specific anti-TT antibodies, as well as total immunoglobulins (Ig), were purified by affinity chromatography on TT-Sepharose or Protein G-Sepharose, respectively. 2-DE unambiguously allowed us to differentiate between the specific humoral responses produced either by humans or by the two xenochimeric mouse models. Anti-TT antibodies produced by humans were polyclonal with a superimposed oligoclonality that was donor-dependent and that did not change upon time. By contrast, immunized hu-PBLe-SCID mice exhibited an evident clonal restriction of the Ig, which increased with time after boosting. Hu-ton-SCID mice showed a clonal diversity which was intermediate between those observed in humans and in hu-PBLe-SCID mice, and which was stable over time. In addition, information was gained by 2-DE, correlating with data obtained by enzyme-linked immunosorbent assay (ELISA), on the isotype composition of the anti-TT IgM response. Altogether, our results clearly demonstrated that the clonal diversity of monospecific antibodies can be appreciated by 2-DE, and that the largest diversity was found in humans when compared to that in xenochimeric models. In addition, mice implanted with pieces of lymphoid organs had the broadest anti-TT Ig diversity, an observation supporting the use of this model for the generation of antibodies with restricted specificity. 相似文献
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Meigen Zhang State Key Laboratory of Atmospheric Boundary Layer Physics Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing P. R. China Tel: -- E-mail: mgzhang@mail.iap.ac.cn 《中国颗粒学报》2004,2(5):192-195
1. Introduction Atmospheric aerosols are a chemical mixture of solid and liquid particles suspended in ambient air. They range in size from the smallest superfine particles, having di-ameters of a few nano-meters (nm), to coarse mode parti-cles, with diameters of several micrometers (mm) or more. From a climatic point of view, probably the most critical subset of atmospheric aerosols are those in the fine or accumulation mode, having diameters ranging from about 0.1 mm to a few micrometers. Th… 相似文献
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U. Bogner R. Seel F. Graf C. R. Pollock D. A. Jennings F. R. Petersen R. E. Drullinger E. C. Beaty J. S. Wells J. L. Hall H. P. Layer K. M. Evenson Ch. Salomon Ch. Bréant A. van Lerberghe G. Camy Ch. J. Bordé K. J. Siemsen H. D. Riccius A. S. Südbø Guiguang Xiong 《Applied physics. B, Lasers and optics》1982,29(3):152-156
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Heselich A Frohns F Frohns A Naumann SC Layer PG 《Photochemistry and photobiology》2012,88(1):135-146
Near infrared (NIR) and X-rays are radiations from different sides of the wavelength spectrum but both are used during medical treatments, as they have severe impacts on cellular processes, including metabolism, gene expression, proliferation and survival. However, both radiations differ strictly in their consequences for exposed patients: NIR effects are generally supposed to be positive, mostly ascribed to a stimulation of metabolism, whereas X-ray leads to genetic instability, an increase of reactive oxygen species (ROS) and DNA damages and finally to cellular death by apoptosis in tumor cells. Since genomic stability after X-irradiation depends on the mitochondrial metabolism, which is well known to be regulated by NIR, we analyzed the impact of NIR on cellular responses of fibroblasts, retinal progenitor cells and keratinocytes to X-radiation. Our data show that previous exposure to naturally occurring doses of nonthermal NIR combined with clinically relevant X-ray doses leads to (1) increased genomic instability, indicated by elevated ratios of mitotic catastrophes, (2) increased ROS, (3) higher amounts of X-irradiated cells entering S-phase and (4) impaired DNA double-strand break repair. Taken together, our data show tremendous effects of NIR on cellular responses to X-rays, probably affecting the results of radiotherapy after NIR exposure during cancer treatment. 相似文献
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M. Hanisch F. Helus K. Layer W. Maier-Borst 《Journal of Radioanalytical and Nuclear Chemistry》1987,117(6):369-378
The14N/p, /11C-reaction was studied in different N2/H2-mixtures. The products are [11C]-CO2, [11C]-CO and [11C]-CH4. The yield ratio may be controlled by varying the bombardment conditions. High pressure, high H2-content, high beam current and high proton energy shift the ratio towards [11C]-CH4. Lower beam current and lower proton energy increase the yield of [11C]-CO2. The production of [11C]-CO is constant over a wide range of conditions /about 10%/. For the production of [11C]-CH4 in good yield a target gas holder for high pressures has been developed. Details are given in Fig. 7. This target gas holder was filled with 5% H2 in N2 at 3×106 Pa. Proton irradiation of the mixture gives a typical yield of [11C]-CH4 of 400–500 mCi at a beam current of 15–20 A within 20 min. Only traces of other11C-labelled compounds could be detected under these conditions. 相似文献
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We consider the presence of cosmic string-induced density fluctuations in the early universe at temperatures below the electroweak
phase transition temperature. Resulting temperature fluctuations can restore the electroweak symmetry locally, depending on
the amplitude of fluctuations and the background temperature. The symmetry will be spontaneously broken again in a given region
as the temperature drops there (for fluctuations with length scales smaller than the horizon), resulting in the production
of baryon asymmetry. The time-scale of the transition will be governed by the wavelength of fluctuation and, hence, can be
much smaller than the Hubble time. This leads to strong enhancement in the production of baryon asymmetry for a second-order
electroweak phase transition as compared to the case when transition happens due to the cooling of the universe via expansion.
For a two-Higgs doublet model (with appropriate CP violation), we show that one can get the required baryon asymmetry if fluctuations
propagate without getting significantly damped. If fluctuations are damped rapidly, then a volume factor suppresses the baryon
production, though it is still 3–4 orders of magnitude larger than the conventional case of second-order transition. 相似文献