ON THE DISCOVERY OF COHERENT BREMSSTRAHLUNG IN A SINGLE CRYSTAL AT THE FRASCATI NATIONAL LABORATORIES

2010 ◽  
Vol 25 (supp01) ◽  
pp. 1-8 ◽  
Author(s):  
G. BARBIELLINI ◽  
G.P. MURTAS ◽  
S.B. DABAGOV
Keyword(s):  
Single Crystal ◽  
Relativistic Electron ◽  
Research Program ◽  
Coherent Radiation ◽  
Coherent Bremsstrahlung ◽  
First Results ◽  
Channeling Radiation ◽  
First Time ◽  
Innovative Techniques ◽  
Intense Research

Since the end of 1950s the Frascati National Laboratories have started intense research program devoted to studying the coherent phenomena of relativistic electron interactions in crystals. First results were impressive: Frascati's Spectrometer has first detected coherent radiation by electrons in crystals, i.e. coherent bremsstrahlung. The discovery not only proved the Ferretti-Uberall prediction, but also has corrected the theory of coherent bremstrahlung. Carrying out intensive studies on coherent radiation phenomena in crystals a number of innovative techniques to measure fine features of radiation, such as polarization measurents, was developed. The Frascati's group was even close for the first time to observe channeling radiation discovered about two decades later the pioneering work on coherent bremsstrahlung.

Influence of Metal Substitution on the Pressure-Induced Phase Change in Flexible Zeolitic Imidazolate Frameworks

2018 ◽  
Author(s):  
C. Michael McGuirk ◽  
Tomče Runčevski ◽  
Julia Oktawiec ◽  
Ari Turkiewicz ◽  
mercedes K. taylor ◽  
...  
Keyword(s):  
Phase Change ◽  
Single Crystal ◽  
Gas Adsorption ◽  
High Capacity ◽  
Phase Changes ◽  
Zeolitic Imidazolate Frameworks ◽  
Metal Substitution ◽  
Heat Management ◽  
Metal Organic ◽  
First Time

<p>Metal–organic frameworks that display step-shaped adsorption profiles arising from discrete pressure-induced phase changes are promising materials for applications in both high-capacity gas storage and energy-efficient gas separations. The thorough investigation of such materials through chemical diversification, gas adsorption measurements, and <i>in situ </i>structural characterization is therefore crucial for broadening their utility. We examine a series of isoreticular, flexible zeolitic imidazolate frameworks (ZIFs) of the type M(bim)<sub>2</sub> (SOD; M = Zn<sup> </sup>(ZIF-7), Co (ZIF-9), Cd (CdIF-13); bim<sup>–</sup> = benzimidazolate), and elucidate the effects of metal substitution on the pressure-responsive phase changes and the resulting CO<sub>2</sub> and CH<sub>4</sub> step positions, pre-step uptakes, and step capacities. Using ZIF-7 as a benchmark, we reexamine the poorly understood structural transition responsible for its adsorption steps and, through high-pressure adsorption measurements, verify that it displays a step in its CH<sub>4 </sub>adsorption isotherms. The ZIF-9 material is shown to undergo an analogous phase change, yielding adsorption steps for CO<sub>2</sub> and CH<sub>4</sub> with similar profiles and capacities to ZIF-7, but with shifted threshold pressures. Further, the Cd<sup>2+</sup> analogue CdIF-13 is reported here for the first time, and shown to display adsorption behavior distinct from both ZIF-7 and ZIF-9, with negligible pre-step adsorption, a ~50% increase in CO<sub>2</sub> and CH<sub>4</sub> capacity, and dramatically higher threshold adsorption pressures. Remarkably, a single-crystal-to-single-crystal phase change to a pore-gated phase is also achieved with CdIF-13, providing insight into the phase change that yields step-shaped adsorption in these flexible ZIFs. Finally, we show that the endothermic phase change of these frameworks provides intrinsic heat management during gas adsorption. </p>

scholarly journals Coherent radiation from an intense relativistic electron beam rotating in a background plasma

1978 ◽  
Vol 32 (2) ◽  
pp. 88-90 ◽  
Author(s):  
V. Granatstein ◽  
C. Roberson ◽  
G. Benford ◽  
D. Tzach ◽  
S. Robertson
Keyword(s):  
Electron Beam ◽  
Relativistic Electron ◽  
Relativistic Electron Beam ◽  
Coherent Radiation ◽  
Background Plasma

scholarly journals AGN Spectra as Seen by the Infrared Space Observatory: First Results

1997 ◽  
Vol 159 ◽  
pp. 333-336
Author(s):  
D. Lutz ◽  
R. Genzel ◽  
E. Sturm ◽  
A.F.M. Moorwood ◽  
E. Oliva ◽  
...  
Keyword(s):  
Fine Structure ◽  
Short Wavelength ◽  
Molecular Hydrogen ◽  
Molecular Gas ◽  
Space Observatory ◽  
Infrared Space Observatory ◽  
First Results ◽  
External Galaxies ◽  
First Time ◽  
Fine Structure Lines

AbstractWe discuss 2.5–45 µm spectra of the Circinus galaxy and of Cen A, obtained with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory. The large number of detected ionic fine structure lines, observable also in visually obscured sources, provides strong constraints on the shape of the ionizing spectrum, which is found to exhibit a UV bump peaking at ~ 70 eV in the case of Circinus. Pure rotational emission of molecular hydrogen, directly probing warm molecular gas, can for the first time be detected in external galaxies.

scholarly journals Intra-Day Variability Observations of Two Dozens of Blazars at 4.8 GHz

Universe ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 15
Author(s):  
Xiang Liu ◽  
Xin Wang ◽  
Ning Chang ◽  
Jun Liu ◽  
Lang Cui ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Forthcoming Paper ◽  
Galactic Latitude ◽  
Local Interstellar Medium ◽  
Bl Lac Objects ◽  
Spectrum Radio ◽  
First Results ◽  
First Time ◽  
Source Structure

Two dozens of radio loud active galactic nuclei (AGNs) have been observed with Urumqi 25 m radio telescope in order to search for intra-day variability (IDV). The target sources are blazars (namely flat spectrum radio quasars and BL Lac objects) which are mostly selected from the observing list of RadioAstron AGN monitoring campaigns. The observations were carried out at 4.8 GHz in two sessions of 8–12 February 2014 and 7–9 March respectively. We report the data reduction and the first results of observations. The results show that the majority of the blazars exhibit IDV in 99.9% confidence level, some of them show quite strong IDV. We find the strong IDV of blazar 1357 + 769 for the first time. The IDV at centimeter-wavelength is believed to be predominately caused by the scintillation of blazar emission through the local interstellar medium in a few hundreds parsecs away from Sun. No significant correlation between the IDV strength and either redshift or Galactic latitude is found in our sample. The IDV timescale along with source structure and brightness temperature analysis will be presented in a forthcoming paper.

Influence of alloying systems on the properties of single crystal nickel-based superalloys

2021 ◽  
Vol 112 (10) ◽  
pp. 794-799
Author(s):  
Alexander Glotka ◽  
Vadim Ol’shanetskii
Keyword(s):  
Single Crystal ◽  
Regression Models ◽  
Strength Properties ◽  
Term Limits ◽  
Alloying Elements ◽  
Structure Stability ◽  
Plastic Properties ◽  
Crystal Lattices ◽  
Predictive Regression ◽  
First Time

Abstract The purpose of the investigation was to obtain the predictive regression models that help correct the calculation of the mechanical properties of single crystal nickel-based superalloys without conducting prior experiments. The paper considers the influence of alloying elements on their tendency to form phases in foundry nickel-based superalloys. Using the elements influence on the phase formation, the coefficient Kc’ of the ratio of alloying elements for this class of alloys was set for the first time. We have revealed the short correlation of the ratio Kc’ with the dimensional misfit of γ and γ’ crystal lattices. Also, a high probability to predict the misfit for multicomponent nickel systems is shown, which significantly affected the strength properties. The regression models of correlation dependencies on the dimensional γ/γ’- misfit were offered to predict the short-term and long-term limits of the strength of alloys. We determined the operating temperature at which the misfit value should decrease to zero. The structure stability should increase because of the structural stresses minimizing. This has a positive effect on strength and plastic properties.

The effect of device geometry and crystal orientation on the stress-dependent offset voltage of 3C–SiC(100) four terminal devices

2015 ◽  
Vol 3 (34) ◽  
pp. 8804-8809 ◽  
Author(s):  
Afzaal Qamar ◽  
Hoang-Phuong Phan ◽  
Jisheng Han ◽  
Philip Tanner ◽  
Toan Dinh ◽  
...  
Keyword(s):  
Single Crystal ◽  
Crystal Orientation ◽  
Offset Voltage ◽  
Device Geometry ◽  
Stress Dependent ◽  
P Type ◽  
The Impact ◽  
First Time

This communication reports for the first time, the impact of device geometry on the stress-dependent offset voltage of single crystal p-type 3C–SiC four terminal devices.

First Results from the VULCAN Diffractometer at the SNS

2010 ◽  
Vol 652 ◽  
pp. 105-110 ◽  
Author(s):  
X.L. Wang ◽  
Thomas Holden ◽  
A.D. Stoica ◽  
K. An ◽  
H.D. Skorpenske ◽  
...  
Keyword(s):  
Neutron Beam ◽  
Research Opportunities ◽  
Instrument Performance ◽  
Measurement Results ◽  
First Results ◽  
Design Calculations ◽  
New Research ◽  
First Time

On Friday June 26, 2009, the neutron beam shutter for the VULCAN diffractometer at the SNS was opened for the first time. Initial measurements to characterize the instrument performance are reported. It is shown that the measurement results are by and large in agreement with design calculations. New research opportunities with VULCAN are discussed.

scholarly journals First Results from Insemination With Sex-Sorted Semen in Dairy Heifers in Macedonia

2015 ◽  
Vol 38 (1) ◽  
pp. 107-111
Author(s):  
Ljupche Kochoski ◽  
Zoran Filipov ◽  
Ilcho Joshevski ◽  
Stevche Ilievski ◽  
Filip Davkov
Keyword(s):  
Pregnancy Rate ◽  
Transrectal Ultrasound ◽  
Gestation Length ◽  
Dairy Heifers ◽  
Holstein Friesian ◽  
First Results ◽  
Long Time ◽  
The Usa ◽  
Normal Gestation ◽  
First Time

Abstract Science has been searching for a long time for a reliable method for controlling the sex of mammalian offspring. Recently, the application of specific modern cellular methodologies has led to the development of a flow cytometric system capable of differentiating and separating living X- and Y-chromosome-bearing sperm cells in amounts suitable for AI and therefore, commercialization of this sexing technology. The aim of this work was to present the first results of heifers that introduce bovine AI with sex sorted semen, for the first time in Macedonia. Insemination with sex sorted cryopreserved semen (2×106 spermatozoa per dose) imported from the USA was done at two dairy farms in ZK Pelagonija. In total, 74 heifers (Holstein Friesian) were inseminated. Inseminations were carried out in a timely manner following a modified OvSynch protocol. During the insemination, the sperm was deposited into the uterine horn ipsi lateral to the ovary where a follicle larger than 1.6 cm was detected by means of transrectal ultrasound examination. Pregnancy was checked by ultrasound on day 30 after the insemination. Overall, the average pregnancy rate in both farms was 43,24% (40,54% and 45,95%, for farm 1 and farm 2, respectively). All pregnant heifers delivered their calves following a normal gestation length (274,3 days in average) and of the 32 born calves, 30 (93,75%) were female. In conclusion, since the first results from inseminations with sex-sorted semen in dairy heifers in Macedonia are very promising, the introduction of this technique may bring much benefit to the local dairy sector. Average pregnancy rate seems similar with results obtained following ‘regular’ inseminations, notwithstanding the relatively low number of spermatozoa per insemination dose. Due to the latter, we however recommend inseminations only to be carried out by experienced technicians followinga TAI protocol and ultrasound examinations of the ovaries prior to insemination.

scholarly journals THE FIRST DATA ON THE MEIOBENTHOS OF LAKE NERO

2020 ◽  
pp. 61-72
Author(s):  
V. Gusakov
Keyword(s):  
Species Richness ◽  
Aquatic Organisms ◽  
Quantitative Structure ◽  
Community Members ◽  
Volga River ◽  
Volga River Basin ◽  
Qualitative And Quantitative ◽  
First Results ◽  
High Species Richness ◽  
First Time

The paper provides the first results of a study of the qualitative and quantitative structure of the community of bottom meiofauna (meiobenthos) in shallow, hypereutrophic Lake Nero (Volga River basin, Yaroslavl region, Russia). In the samples, collected in early September 2017, 106 representatives from 16 systematic groups of aquatic organisms were found. About half of them had not been previously recorded in the lake's fauna. The species composition of Gastrotricha, Nematoda, Tardigrada, Acari, Harpacticoida, and Ostracoda was analyzed in the water body for the first time. It is established that at the end of the vegetation season, the lake's meiobenthos characterizes by relatively high species richness, diversity, and quantitative parameters. The circle of the main (dominant) community members in the studied period was outlined.

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