120 research outputs found
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Contact-cooled U-monochromators for high heat load x-ray beamlines
This paper describes the design, expected performance, and preliminary test results of a contact-cooled monochromator for use on high heat load x-ray beamlines. The monochromator has a cross section in the shape of the letter U. This monochromator should be suitable for handing heat fluxes up to 5 W/square millimeter. As such, for the present application, it is compatible with the best internally cooled crystal monochromators. There are three key features in the design of this monochromator. First, it is contact cooled, thereby eliminating fabrication of cooling channels, bonding, and undesirable strains in the monochromator due to coolant-manifold-to-crystal-interface. Second, by illuminating the entire length of the crystal and extracting the central part of the reflected beam, sharp slope changes in the beam profile and thus slope errors are avoided. Last, by appropriate cooling of the crystal, tangential slope error can be substantially reduced
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A plan for the development of superconducting Undulator prototypes for LCLS-II and future FELs
Undulators serve as the primary source of radiation for modern storage rings, and more recently for the advent of Free-Electron Lasers (FELs). The performance of future FELs can be greatly enhanced using the much higher magnetic fields of superconducting undulators (SCU) [1]. For example, the LCLS-II hard x-ray undulator can be shortened by up to 70 m using an SCU in place of a PMU (permanent magnet undulator), or its spectral performance can be critically improved when using a similar length. In addition, SCUs are expected to be orders of magnitude less sensitive to radiation dose; a major issue at LCLS-II with its 1-MHz electron bunch rate. We present a funded R&D collaboration between SLAC, ANL, and LBNL, which aims to demonstrate the viability of superconducting undulators for FELs by building, testing, measuring, and tuning two 1.5-m long planar SCU prototypes using two different technologies: NbTi at ANL and Nb Sn at LBNL. Our goal is to review and reassess the LCLS-II HXR baseline plans (PMU) in July of 2015, after the development and evaluation of both prototypes, possibly in favor of an SCU for LCLS-II.
A single-solenoid pulsed-magnet system for single-crystal scattering studies
We present a pulsed-magnet system that enables x-ray single-crystal
diffraction in addition to powder and spectroscopic studies with the magnetic
field applied on or close to the scattering plane. The apparatus consists of a
single large-bore solenoid, cooled by liquid nitrogen. A second independent
closed-cycle cryostat is used for cooling samples near liquid helium
temperatures. Pulsed magnetic fields close to T with a
zero-to-peak-field rise time of 2.9 ms are generated by discharging a 40
kJ capacitor bank into the magnet coil. The unique characteristic of this
instrument is the preservation of maximum scattering angle ()
on the entrance and exit sides of the magnet bore by virtue of a novel
double-funnel insert. This instrument will facilitate x-ray diffraction and
spectroscopic studies that are impractical, if not impossible, to perform using
split-pair and narrow-opening solenoid magnets, and offers a practical solution
for preserving optical access in future higher-field pulsed magnets.Comment: Accepted for publication in Rev. Sci. Instru
First Observation of Self-Amplified Spontaneous Emission in a Free-Electron Laser at 109 nm Wavelength
We present the first observation of Self-Amplified Spontaneous Emission
(SASE) in a free-electron laser (FEL) in the Vacuum Ultraviolet regime at 109
nm wavelength (11 eV). The observed free-electron laser gain (approx. 3000) and
the radiation characteristics, such as dependency on bunch charge, angular
distribution, spectral width and intensity fluctuations all corroborate the
existing models for SASE FELs.Comment: 6 pages including 6 figures; e-mail: [email protected]
Эффективность внутриплевральной пролонгированной фотодинамической терапии у больной со злокачественным плевритом
Current approaches to diagnostics and treatment of patients with pleural metastases complicated by malignant pleuritis are reviewed. The method of intrapleural photodynamic therapy with photosens developed in P.A.Herzen MCRI for primary and metastatic pleural diseases complicated by malignant pleuritis is represented; for 66 patients there were good efficacy as pleurodesis in 92.4% of cases. The case of intrapleural photodynamic therapy in female patient with pleural mesothelioma complicated by malignant pleuritis with good short- and longterm results and significantly improved quality of life is reported.В работе рассмотрены современные подходы к диагностике и лечению больных с первичным и метастатическим поражением плевры, осложненным злокачественным плевритом. Представлена разработанная в МНИОИ им. П.А. Герцена методика внутриплевральной фотодинамической терапии с препаратом фотосенс при первичном и метастатическом поражении плевры, осложненным злокачественным плевритом, показавшая на примере применения у 66 больных хорошую эффективность в виде наступления плевродеза в 92,4% случаев. Приведено наблюдение успешного применения методики внутриплевральной фотодинамической терапии у пациентки с мезотелиомой плевры, осложненной злокачественным плевритом, позволившей добиться хорошего непосредственного и длительного эффекта, а также значительно улучшить качество жизни
Self-amplified spontaneous emission saturation at the Advanced Photon Source free-electron laser (abstract) (invited)
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AI is a viable alternative to high throughput screening: a 318-target study
: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery
Enzymatic oligomerization and polymerization of arylamines: state of the art and perspectives
The literature concerning the oxidative oligomerization and polymerization of various arylamines, e.g., aniline, substituted anilines, aminonaphthalene and its derivatives, catalyzed by oxidoreductases, such as laccases and peroxidases, in aqueous, organic, and mixed aqueous organic monophasic or biphasic media, is reviewed. An overview of template-free as well as template-assisted enzymatic syntheses of oligomers and polymers of arylamines is given. Special attention is paid to mechanistic aspects of these biocatalytic processes. Because of the nontoxicity of oxidoreductases and their high catalytic efficiency, as well as high selectivity of enzymatic oligomerizations/polymerizations under mild conditions-using mainly water as a solvent and often resulting in minimal byproduct formation-enzymatic oligomerizations and polymerizations of arylamines are environmentally friendly and significantly contribute to a "green'' chemistry of conducting and redox-active oligomers and polymers. Current and potential future applications of enzymatic polymerization processes and enzymatically synthesized oligo/polyarylamines are discussed
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