6,133 research outputs found
Arbitrary beam control using passive lossless metasurfaces enabled by orthogonally-polarized custom surface waves
For passive, lossless impenetrable metasurfaces, a design technique for
arbitrary beam control of receiving, guiding, and launching is presented.
Arbitrary control is enabled by a custom surface wave in an orthogonal
polarization such that its addition to the incident (input) and the desired
scattered (output) fields is supported by a reactive surface impedance
everywhere on the reflecting surface. Such a custom surface wave (SW) takes the
form of an evanescent wave propagating along the surface with a spatially
varying envelope. A growing SW appears when an illuminating beam is received.
The SW amplitude stays constant when power is guided along the surface. The
amplitude diminishes as a propagating wave (PW) is launched from the surface as
a leaky wave. The resulting reactive tensor impedance profile may be realized
as an array of anisotropic metallic resonators printed on a grounded dielectric
substrate. Illustrative design examples of a Gaussian beam
translator-reflector, a probe-fed beam launcher, and a near-field focusing lens
are provided
Aqueous Phase C-H Bond Oxidation Reaction of Arylalkanes Catalyzed by a Water-Soluble Cationic Ru(III) Complex [(pymox-Me\u3csub\u3e2\u3c/sub\u3e)\u3csub\u3e2\u3c/sub\u3eRuCl\u3csub\u3e2\u3c/sub\u3e]\u3csup\u3e+\u3c/sup\u3eBF\u3csub\u3e4\u3c/sub\u3e\u3csup\u3e-\u3c/sup\u3e
The cationic complex [(pymox-Me2)RuCl2]+BF4โ was found to be a highly effective catalyst for the CโH bond oxidation reaction of arylalkanes in water. For example, the treatment of ethylbenzene (1.0 mmol) with t-BuOOH (3.0 mmol) and 1.0 mol % of the Ru catalyst in water (3 mL) cleanly produced PhCOCH3 at room temperature. Both a large kinetic isotope effect (kH/kD = 14) and a relatively large Hammett value (ฯ = โ1.1) suggest a solvent-caged oxygen rebounding mechanism via a Ru(IV)-oxo intermediate species
Functional metasurfaces: Do we need normal polarizations?
We consider reciprocal metasurfaces with engineered reflection and
transmission coefficients and study the role of normal (with respect to the
metasurface plane) electric and magnetic polarizations on the possibilities to
shape the reflection and transmission responses. We demonstrate in general and
on a representative example that the presence of normal components of the
polarization vectors does not add extra degrees of freedom in engineering the
reflection and transmission characteristics of metasurfaces. Furthermore, we
discuss advantages and disadvantages of equivalent volumetric and fully planar
realizations of the same properties of functional metasurfaces.Comment: 3 pages, 2 figures, XXXIInd International Union of Radio Science
General Assembly and Scientific Symposium, paper B7-1, pp. 1-3, Montreal,
Canada, 19-26 August 2017 (invited
Metal-organic chemical vapor deposition of 2D van der Waals materials-The challenges and the extensive future opportunities
The last decade has witnessed significant progress in two-dimensional van der Waals (2D vdW) materials research; however, a number of challenges remain for their practical applications. The most significant challenge for 2D vdW materials is the control of the early stages of nucleation and growth of the material on preferred surfaces to eventually create large grains with digital thickness controllability, which will enable their incorporation into high-performance electronic and optoelectronic devices. This Perspective discusses the technical challenges to be overcome in the metal-organic chemical vapor deposition (MOCVD) growth of 2D group 6 transition metal dichalcogenide (TMD) atomic crystals and their heterostructures, as well as future research aspects in vdW epitaxy for 2D TMDs via MOCVD. In addition, we encourage the traditional MOCVD community to apply their expertise in the field of "2D vdW materials," which will continue to grow at an exponential rate
Relation between Kitaev magnetism and structure in -RuCl
Raman scattering has been employed to investigate lattice and magnetic
excitations of the honeycomb Kitaev material -RuCl and its
Heisenberg counterpart CrCl. Our phonon Raman spectra give evidence for a
first-order structural transition from a monoclinic to a rhombohedral structure
for both compounds. Significantly, only -RuCl features a large
thermal hysteresis, consistent with the formation of a wide phase of
coexistence. In the related temperature interval of K, we observe a
hysteretic behavior of magnetic excitations as well. The stronger magnetic
response in the rhombohedral compared to the monoclinic phase evidences a
coupling between the crystallographic structure and low-energy magnetic
response. Our results demonstrate that the Kitaev magnetism concomitant with
fractionalized excitations is susceptible to small variations of bonding
geometry.Comment: 9 pages, 8 figures, To appear in PR
Probable Case of Neuroleptic Malignant Syndrome Following Administration of Antituberculotic Drugs in a Chlorpromazine-Treated Patient
Neuroleptic malignant syndrome (NMS), a potentially fatal adverse reaction to neuroleptics, is known to occur more often in the initial stage of antipsychotic treatment. We describe a patient with chronic schizophrenia who, in a few days after the addition of antituberculotic drugs to his antipsychotic regimen, developed probable NMS without pyrexia. We reasoned that rifampin, a strong hepatic enzyme inducer, decreased the plasma chlorpromazine concentration of the patient, with the result of cholinergic hyperactivity and finally, the symptoms of NMS. Therefore, physicians should be aware of drug interactions and the likelihood of NMS, and consider antipsychotic dose adjustment when prescribing drugs that may influence pharmacokinetic properties of antipsychotics in a patient with schizophrenia receiving long-term antipsychotic treatment
Pilot scale study of chlorination-induced transport property changes of a seawater reverse osmosis membrane
A pilot-scale study was performed to assess variations of reverse osmosis (RO) membrane water permeance (A) and salt retention (Robs) induced by chlorination and to compare them with those observed at the lab-scale. A chlorination protocol was adapted to expose only the surface active layer (an aromatic polyamide)of a composite RO membrane to consecutive free chlorine doses ranging from 40 to 4000 ppm h, at pH 6.9. Along the long-term filtration of seawater, performed with a 4" spiral wound RO module, we monitored the variations of A, the decrease of Robs and the rate of increase of A with time, and found themquantitatively similar to those reported in previous studies performed at the lab-scale under accelerated exposure conditions. The elemental analysis of the feed and permeate streams revealed that the rejection of divalent ions remained constant (ca. 100%), irrespective of the free chlorine dose reached, whereas the rejection of monovalent ions
of the seawater (mainly sodium, chloride and bromide ions) decreased as the exposure dose increased. Overall, transposing the characterization procedure to the pilot-scale further supports that chlorination of PA, under pH conditions usually found in desalination plants (6.9 to 8.0), is controlled by the concentration of HOCl, as observed from elemental analysis of the surface by XPS
Reorganization of Musical Groups in the Beginning of the 20th Century
There are two fields in Korean traditional music, classical music [a-ak ้
ๆจ] and folk music [minsok-ak ๆฐไฟๆจ]. That means the two are keeping Korean traditional music balanced. In fact, a considerable number of Korean traditional music pieces are legacies from the Chosรตn Dynasty ๆ้ฎฎ(1392-1910), whether they are part of classical music or folk music. Originally there was no distinction between court music and folk music during the Chosรฐn Dynasty. Then, when did classical music and folk music become recognized as the two major fields of Korean traditional music?
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