scholarly journals THE EFFECTS OF RADIATIONS ON BIOLOGICAL SYSTEMS

1932 ◽  
Vol 16 (2) ◽  
pp. 207-220 ◽  
Author(s):  
Raymond Hussey ◽  
William R. Thompson ◽  
Robert Tennant ◽  
Nancy DuVal Campbell
Keyword(s):  
Drosophila Melanogaster ◽  
Larval Stage ◽  
High Frequency ◽  
Biological Systems ◽  
Experimental Treatment ◽  
Living System ◽  
Maximum Effect ◽  
X Ray

The effect of high-frequency x-ray irradiation in prolongation of the larval stage of Drosophila melanogaster has been studied further, and evidence presented of the attainment of a maximum effect followed by a decrease to an almost level plateau in the course curve of average (median) prepupal period (ϕ) as a function of the period of irradiation (t) under otherwise fixed conditions. The variation of effects of the experimental treatment with age of the larvae at the time of irradiation has been demonstrated in both control and irradiated lots, and a strikingly decreased effect observed when ventilation was not supplied as usual. Means of employment of a living system of this type as an indicator of effectiveness of radiation as in phantom depth or other distributional experiments have been presented and their use illustrated.

Tumori in Diverse Specie Del Genere Drosophila

1953 ◽  
Vol 39 (2) ◽  
pp. 117-124 ◽  
Author(s):  
Danko Brncic ◽  
Susie Koref
Keyword(s):  
Drosophila Melanogaster ◽  
Larval Stage ◽  
High Frequency ◽  
Natural Populations ◽  
Mean Value ◽  
Incomplete Penetrance ◽  
Tumor Bearing ◽  
Long Time ◽  
The Cross ◽  
Different Strains

Melanotic bodies, in all similar to the tumors described in Drosophila melanogaster, were found in natural populations of the following species of the genus Drosophila: D. campestris, D. bainderantorum, D. bocainensis. D. griseolineata, D. guaramunú, D. immigrans, D. mediostriata, D. mediopunctata, D. nebulosa, D. repleta, D. simulans, D. sturtevanti, D. virilis, D. willstoni. In stocks maintained in the laboratory for a long time, it was determined that the frequency of tumors varied from 0 to 5‰, with a mean value of 1-2‰. The highest percentage was found in the D. sturtevanti - Belem strain (2.08%). Different strains from a same species had different tumor frequencies. The study of the offspring of tumor bearing flies, and the cross of strains selected for a high frequency of tumors, reveled that these were inherited through rcessive genes of incomplete penetrance. As in D. melanogaster, the tumors appear in the larval stage and regress at the end of this period loading themeselves with melanic pigments. These melanized tumor rests persist in the pupae and adults’ as foreing bodies which apparently produce no important alterations to their bearers.

The Microstructure of Steatite (Protoenstatite)

1985 ◽  
Vol 43 ◽  
pp. 236-237
Author(s):  
W. E. Lee ◽  
A. H. Heuer
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Magnesium Silicate ◽  
Beam Current ◽  
Glassy Matrix ◽  
Angle Of Incidence ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Argon Ions ◽  
High Temperature Polymorph

IntroductionTraditional steatite ceramics, made by firing (vitrifying) hydrous magnesium silicate, have long been used as insulators for high frequency applications due to their excellent mechanical and electrical properties. Early x-ray and optical analysis of steatites showed that they were composed largely of protoenstatite (MgSiO3) in a glassy matrix. Recent studies of enstatite-containing glass ceramics have revived interest in the polymorphism of enstatite. Three polymorphs exist, two with orthorhombic and one with monoclinic symmetry (ortho, proto and clino enstatite, respectively). Steatite ceramics are of particular interest a they contain the normally unstable high-temperature polymorph, protoenstatite.Experimental3mm diameter discs cut from steatite rods (∼10” long and 0.5” dia.) were ground, polished, dimpled, and ion-thinned to electron transparency using 6KV Argon ions at a beam current of 1 x 10-3 A and a 12° angle of incidence. The discs were coated with carbon prior to TEM examination to minimize charging effects.

AN X-RAY MONOCHROMATOR SUITABLE FOR STUDYING BIOLOGICAL SYSTEMS

1986 ◽  
Vol 47 (C8) ◽  
pp. C8-127-C8-133
Author(s):  
R. F. PETTIFER ◽  
C. HERMES
Keyword(s):  
Biological Systems ◽  
X Ray

scholarly journals Sintering, Microstructure, and Dielectric Properties of Copper Borates for High Frequency LTCC Applications

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4017
Author(s):  
Dorota Szwagierczak ◽  
Beata Synkiewicz-Musialska ◽  
Jan Kulawik ◽  
Norbert Pałka
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
High Frequency ◽  
Ceramic Materials ◽  
Sintering Behavior ◽  
Terahertz Time Domain Spectroscopy ◽  
Very High Frequency ◽  
X Ray ◽  
Low Dielectric ◽  
Very High

New ceramic materials based on two copper borates, CuB2O4 and Cu3B2O6, were prepared via solid state synthesis and sintering, and characterized as promising candidates for low dielectric permittivity substrates for very high frequency circuits. The sintering behavior, composition, microstructure, and dielectric properties of the ceramics were investigated using a heating microscope, X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy, and terahertz time domain spectroscopy. The studies revealed a low dielectric permittivity of 5.1–6.7 and low dielectric loss in the frequency range 0.14–0.7 THz. The copper borate-based materials, owing to a low sintering temperature of 900–960 °C, are suitable for LTCC (low temperature cofired ceramics) applications.

Superstructure formation in the solid solution Sc3Pt3−xIn3 (x = 0–0.93)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nataliya L. Gulay ◽  
Rolf-Dieter Hoffmann ◽  
Jutta Kösters ◽  
Yaroslav M. Kalychak ◽  
Stefan Seidel ◽  
...  
Keyword(s):  
Solid Solution ◽  
Diffraction Data ◽  
High Frequency ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Platinum Content ◽  
Arc Melting ◽  
Modulation Vector

Abstract The equiatomic indide ScPtIn (ZrNiAl type, space group P 6 ‾ $‾{6}$ 2m) shows an extended solid solution Sc3Pt3–xIn3. Several samples of the Sc3Pt3–xIn3 series were synthesized from the elements by arc-melting and subsequent annealing, or directly in a high frequency furnace. The lowest platinum content was observed for Sc3Pt2.072(3)In3. All samples were characterized by powder X-ray diffraction and their lattice parameters and several single crystals were studied on the basis of precise single crystal X-ray diffractometer data. The correct platinum occupancy parameters were refined from the diffraction data. Decreasing platinum content leads to decreasing a and c lattice parameters. Satellite reflections were observed for the Sc3Pt3–xIn3 crystals with x = 0.31–0.83. These satellite reflections could be described with a modulation vector ( 1 3 , 1 3 , γ ) $\left(\frac{1}{3},\frac{1}{3},\gamma \right)$ ( γ = 1 2 $\gamma =\frac{1}{2}$ c* for all crystals) and are compatible with trigonal symmetry. The interplay of platinum filled vs. empty In6 trigonal prisms is discussed for an approximant structure with space group P3m1.

The High-frequency Electric Discharge at Low Pressures

1928 ◽  
Vol 24 (2) ◽  
pp. 259-267
Author(s):  
James Taylor ◽  
Wilfrid Taylor
Keyword(s):  
Electric Discharge ◽  
High Frequency ◽  
Electrical Discharges ◽  
X Ray ◽  
High Frequency Oscillations ◽  
Low Pressures

Experiments have been conducted by Gutton, and later by Kirchner, and by Gill and Donaldson upon electrical discharges through gases under the influence of high-frequency oscillations of the order of 107 cycles per second. It was found that the peak voltages required to maintain bright luminous discharges were of the order of 100 volts even when the pressure was as low as that in a soft X-ray tube. The present paper deals with some further studies of these phenomena.

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