scholarly journals Determination of Absolute Structure of Chiral Crystals Using Three-Wave X-ray Diffraction

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1389
Author(s):  
Ksenia Kozlovskaya ◽  
Elena Ovchinnikova ◽  
Jun Kokubun ◽  
Andrei Rogalev ◽  
Fabrice Wilhelm ◽  
...  
Keyword(s):  
Bragg Reflection ◽  
Quantitative Description ◽  
X Rays ◽  
Circularly Polarized ◽  
X Ray ◽  
Left Handed ◽  
The Difference ◽  
The Right ◽  
Chiral Crystals ◽  
Absolute Structure

We propose a new method to determine the absolute structure of chiral crystals, which is based on the chiral asymmetry of multiple scattering diffraction. It manifests as a difference in the azimuthal dependence of the forbidden Bragg reflection intensity measured with left and right circularly polarized X-ray beams. Contrary to the existing ones, the suggested method does not use X-ray anomalous dispersion. The difference between the Renninger scans with circularly polarized X-rays has been experimentally demonstrated for the 001 reflection intensities in the right- and left-handed quartz single crystals. A Jmulti-based code on model-independent three-wave-diffraction approach has been developed for quantitative description of our experimental results. The proposed method can be applied to various structures including opaque, organic and monoatomic crystals, even with only light elements. To determine the type of isomer, the Renninger plot of a single forbidden reflection is sufficient.

scholarly journals Abdominal pain and two x-rays: spot the difference

2012 ◽  
Vol 94 (2) ◽  
pp. e95-e95 ◽  
Author(s):  
Z Rajković ◽  
D Papeš ◽  
S Altarac ◽  
N Arslani
Keyword(s):  
Abdominal Pain ◽  
Portal Vein ◽  
Elective Surgery ◽  
Exploratory Laparotomy ◽  
X Rays ◽  
X Ray ◽  
Artery Embolism ◽  
The Difference ◽  
Bilioenteric Fistula ◽  
The Right

We present two patients with air found in the right upper quadrant on standard abdominal x-ray. One was diagnosed with pneumobilia and underwent elective surgery for a bilioenteric fistula. The other was diagnosed with portal vein gas and underwent an emergency exploratory laparotomy at which a superior mesenteric artery embolism was found. The differential diagnostic criteria for pneumobilia and portal vein gas are described. If portal venous gas is found on x-ray in patients with abdominal pain, it is recommended that management is aggressive, meaning an emergency exploratory laparotomy, because mortality in such cases is approximately 75%.

The stability and screw sense of the α -helix in poly- β -benzyl-L-aspartate

1960 ◽  
Vol 259 (1296) ◽  
pp. 110-128 ◽  
Keyword(s):  
Optical Rotatory Dispersion ◽  
Molecular Models ◽  
X Ray Diffraction ◽  
X Ray ◽  
Left Handed ◽  
The Difference ◽  
Diffraction Patterns ◽  
The Stability ◽  
Α Helix ◽  
The Right

A number of polymers and copolymers containing β -benzyl-L-aspartate has been prepared and their optical rotatory dispersion in a variety of solvents has been measured. The results of these measurements together with studies of infra-red spectra, X-ray diffraction patterns, deuteration rates and molecular models lead to the following conclusions. (i) The α -helical form of poly- β -benzyl-L-aspartate is considerably less stable relative to the solvated randomly coiled form than that of poly- γ -benzyl-L-glutamate. (ii) The left-handed α -helix of poly- β -benzyl-L-aspartate is more stable than the right-handed one. (iii) The difference in stability between the two senses of α -helix is much less in the case of poly- β -benzyl-L-aspartate than in that of poly- γ -benzyl-L-glutamate or poly-L-alanine.

Modulation instability in nonlinear chiral fiber

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Demissie Jobir Gelmecha ◽  
Ram Sewak Singh
Keyword(s):  
Theoretical Model ◽  
Numerical Simulations ◽  
Pulse Propagation ◽  
Modulation Instability ◽  
Constitutive Relations ◽  
Gain Spectrum ◽  
Circularly Polarized ◽  
Left Handed ◽  
Simulation Results ◽  
The Difference

AbstractIn this paper, the rigorous derivations of generalized coupled chiral nonlinear Schrödinger equations (CCNLSEs) and their modulation instability analysis have been explored theoretically and computationally. With the consideration of Maxwell’s equations and Post’s constitutive relations, a generalized CCNLSE has been derived, which describes the evolution of left-handed circularly polarized (LCP) and right-handed circularly polarized (RCP) components propagating through single-core nonlinear chiral fiber. The analysis of modulation instability in nonlinear chiral fiber has been investigated starting from CCNLSEs. Based on a theoretical model and numerical simulations, the difference on the modulation instability gain spectrum in LCP and RCP components through chiral fiber has been analyzed by considering loss and chirality into account. The obtained simulation results have shown that the loss distorts the sidebands of the modulation instability gain spectrum, while chirality modulates the gain for LCP and RCP components in a different manner. This suggests that adjusting chirality strength may control the loss, and nonlinearity simultaneously provides stable modulated pulse propagation.

Diamond channel-cut crystals for high-heat-load beam-multiplexing narrow-band X-ray monochromators

2021 ◽  
Vol 28 (6) ◽  
Author(s):  
Yuri Shvyd'ko ◽  
Sergey Terentyev ◽  
Vladimir Blank ◽  
Tomasz Kolodziej
Keyword(s):  
Heat Load ◽  
Narrow Band ◽  
Bragg Reflection ◽  
High Heat ◽  
High Repetition Rate ◽  
X Rays ◽  
Ray Optics ◽  
X Ray ◽  
Load Beam ◽  
High Heat Load

Next-generation high-brilliance X-ray photon sources call for new X-ray optics. Here we demonstrate the possibility of using monolithic diamond channel-cut crystals as high-heat-load beam-multiplexing narrow-band mechanically stable X-ray monochromators with high-power X-ray beams at cutting-edge high-repetition-rate X-ray free-electron laser (XFEL) facilities. The diamond channel-cut crystals fabricated and characterized in these studies are designed as two-bounce Bragg reflection monochromators directing 14.4 or 12.4 keV X-rays within a 15 meV bandwidth to 57Fe or 45Sc nuclear resonant scattering experiments, respectively. The crystal design allows out-of-band X-rays transmitted with minimal losses to alternative simultaneous experiments. Only ≲2% of the incident ∼100 W X-ray beam is absorbed in the 50 µm-thick first diamond crystal reflector, ensuring that the monochromator crystal is highly stable. Other X-ray optics applications of diamond channel-cut crystals are anticipated.

scholarly journals A high-efficiency and ultrathin transmission-type circular polarization converter based on surface structure

2021 ◽  
Vol 8 ◽  
pp. 4
Author(s):  
Peng Xu ◽  
Wei Xiang Jiang ◽  
Xiao Cai ◽  
Yue Gou ◽  
Tie Jun Cui
Keyword(s):  
High Efficiency ◽  
Transmission Mode ◽  
Polarization Converter ◽  
Periodic Surface ◽  
Circularly Polarized ◽  
Left Handed ◽  
Via Holes ◽  
Working Frequency ◽  
The Right ◽  
Good Agreement

In this paper, we propose, design and fabricate a kind of ultrathin and high-efficiency circularly polarization converter based on artificially engineered surfaces in the transmission mode. The converter is composed of double-layer periodic surface structures with cross slots. The top and bottom layers are printed on both sides of the F4B substrate and connected by metallic via holes. The proposed converter can transform the right-handed circularly polarized incident electromagnetic (EM) wave to a left-handed circularly-polarized one with near-unity efficiency in the transmission mode, or vice versa. We explain the conversion mechanism based on numerical simulations and equivalent circuit (EC) theory. The measured result has a good agreement with the simulated one in the working frequency band. Such ultrathin polarization converters can be used in wireless microwave communication, remote sensing, and EM imaging where circularly polarization diversity is needed.

Magnetic Structure of Multilayers from Soft-X-Ray Magnetic Circular Dichroism

1994 ◽  
Vol 375 ◽  
Author(s):  
C. T. Chen ◽  
Y. U. Idzerda ◽  
C.-C. Kao ◽  
L. H. Tjeng ◽  
H.-J. Lin ◽  
...  
Keyword(s):  
Thin Films ◽  
Circular Dichroism ◽  
Magnetic Circular Dichroism ◽  
Magnetic Thin Films ◽  
X Rays ◽  
X Ray ◽  
Specific Manner ◽  
Left And Right ◽  
The Difference ◽  
Circular Dichroïsm

AbstractSoft-x-ray magnetic circular dichroism (MCD) is the difference between the absorptivity or reflectivity of left and right circularly polarized soft-x-rays at the magnetically interesting L2,3- edges of 3d transition metals or the M4,5-edges of the 4f rare earth elements. Thanks to its large absorption cross-section and strong MCD effect, this technique has become a powerful new means for probing, in an element- and site-specific manner, the magnetic properties of ultra-thin films and multilayers. Soft-x-ray MCD experiments, recently conducted at the Dragon beamline, are utilized to demonstrate the recent progress in this technique and its applications in the research of magnetic thin films.

scholarly journals The sensitivity of atomic analysis by X-rays

1932 ◽  
Vol 135 (828) ◽  
pp. 637-656 ◽  
Keyword(s):  
Atomic Number ◽  
Target Material ◽  
High Sensitivity ◽  
Major Constituent ◽  
X Rays ◽  
Depth Of Penetration ◽  
X Ray ◽  
Constituent Element ◽  
The Difference ◽  
Atomic Analysis

In a previous paper it was shown that 0·0007 per cent, of 29 Cu and 0·0003 per cent, of 26 Fe could be detected in 30 Zn by atomic analysis by X-ray spectroscopy. This sensitivity is greater than that which was claimed by Noddack, Tacke, and Berg, who set the limit at about 0·1 per cent, for non-metals, and by Hevesy, who stated it to be about 0·01 per cent, for an element present in an alloy. It was later suggested by Hevesy that the high value of the sensitivity which we found might result from the fact that some of the alloys we had used were composed of elements of almost equal atomic number, and that the sensitivity would be smaller for a constituent of low atomic number mixed with a major constituent of high atomic number. To elucidate these disagreements we have made further observations of the sensitivity with elements of different atomic number and have investigated the conditions which can influence the sensitivity. The Factors Determining Sensitivity . The detection of one element in a mixture of elements depends upon the identification of its K or L lines in the general spectrum emitted by the mixture under examination. The intensity with which these lines are excited in the target (“excited intensity”) is proportional to the number of atoms of the constituent element excited, i. e ., to its concentration and to the volume of the target in which the cathode ray energy is absorbed. The depth of penetration of the cathode rays is determined by the density of the target material and by their velocity ( i. e ., by the voltage applied to the X-ray tube). Schonland has shown that the range of homogeneous cathode rays in different elements, expressed as a mass per unit area, is approximately constant and is independent of the atomic number of the absorbing element. When their velocity is increased, the cathode rays will penetrate to a greater depth, and therefore a greater number of atoms of all constituents will be ionised. This will increase the “excited intensity” of the lines due to the particular constituent sought equally with those lines of the other elements present. The intensity of a line further depends upon the difference between the voltage applied to the X-ray tube and that necessary to excite the series. For these reasons, a high applied voltage is required for a high sensitivity.

scholarly journals Dual-Circularly Polarized 60 GHz Beam-Steerable Antenna Array with 8 × 8 Butler Matrix

2020 ◽  
Vol 10 (7) ◽  
pp. 2413 ◽  
Author(s):  
Yuntae Park ◽  
Jihoon Bang ◽  
Jaehoon Choi
Keyword(s):  
Circular Polarization ◽  
Antenna Array ◽  
Mutual Coupling ◽  
Beam Steering ◽  
60 Ghz ◽  
Circularly Polarized ◽  
Butler Matrix ◽  
Left Handed ◽  
Steerable Antenna ◽  
The Right

A beam-steerable dual-circularly polarized 60 GHz antenna array is proposed. A 1 × 4 dual-fed stacked patch antenna array is integrated with an 8 × 8 Butler matrix. By utilizing the 8 × 8 Butler matrix, the proposed antenna array generates dual-circular polarization with beam-steering capability. The proposed antenna array system demonstrates good reflection coefficients in the frequency band ranging from 55.3 GHz to 64.9 GHz and has a mutual coupling of less than −10 dB over the frequency range of 57.5 GHz–63.2 GHz. At 60 GHz, the maximum gains and beam-steering angles for input ports 2, 4, 5, and 7 are 9.39 dBi at −38°, 10.67 dBi at −11°, 10.63 dBi at +11°, and 9.38 dBi at +39°, respectively. It is also demonstrated that the dual-polarization is well formed by switching the excitation ports. The right-handed circular polarization (RHCP) is formed when four ports from port 1 to port 4 are excited and left-handed circular polarization (LHCP) is formed when four ports from port 5 to port 8 are excited. The proposed antenna array system could be a good candidate for millimeter-wave 5G applications that require wide beam coverage and polarization diversity.

scholarly journals A Method to Optimize the Electron Spectrum for Simulating Thermo-Mechanical Response to X-ray Radiation

Symmetry ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 59
Author(s):  
Xianwen Ran ◽  
Bo Wang ◽  
Kun Zhang ◽  
Wenhui Tang
Keyword(s):  
Electron Spectrum ◽  
Mechanical Response ◽  
Least Squares Method ◽  
Mechanical Deformation ◽  
X Rays ◽  
Linear Least Squares ◽  
X Ray ◽  
Relativistic Electron Beams ◽  
Transport Code ◽  
The Difference

The X-ray pulse originating from high altitude nuclear detonation (HAND) is mainly soft X-ray and its intensity is high enough to gasify the penetrated material and then lead to the severe thermo-mechanical deformation of unpenetrated material from the gasified blow-off effect. This effect cannot be directly reproduced in a lab for the lack of the X-ray source like HAND. At present, the low-energy relativistic electron beams resulting from an electron accelerator are usually used to approximately reproduce this effect, but the difference in the energy-deposited profile in materials between the electron and X-ray cannot be eliminated. In this paper, the symmetric linear least squares method was used to optimize the electron spectrum, and the general Monte Carlo N-Particle Transport Code calculations showed the optimized spectrum can produce the same energy-deposited profile in aluminum, copper, and tantalum with the soft X-rays like 1 keV or 3 keV spectrums. This indicates that it is possible to simulate the severe thermo-mechanical deformation resulting from HAND using the optimized electron spectrums.

Foot Performance of Right- and Left-Handers: A Question of Environmental Influence

1995 ◽  
Vol 80 (2) ◽  
pp. 671-674 ◽  
Author(s):  
Carl Gabbard ◽  
Susan Hart
Keyword(s):  
Environmental Influence ◽  
Hand Preference ◽  
Adequate Explanation ◽  
Driving Experience ◽  
Left Hand ◽  
Left Handed ◽  
Right Hand ◽  
Theoretical Perspectives ◽  
The Difference ◽  
The Right

Prior research has shown that right-handed adults perform better on a speed-tapping task with the right hand and right foot, while left-handers execute more rapidly with the left hand and right foot. Speculation is that environmental influence, most likely driving experience, may account for the right-foot bias. To examine this hypothesis further, 48 young right- and left-handed children were tested on a similar protocol. Analyses indicated no significant differences in foot performance within hand-preference groups. Since these findings do not complement reports for adults, factors such as experience or maturation might contribute to the difference. Were patterns similar, the effect of environmental influence would be assumed to be small. However, much more evidence is needed before an adequate explanation can be developed. The issue of possible environmental influence is discussed from various theoretical perspectives.

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