scholarly journals Direct observation of slow fission from the width of K x-ray line

2018 ◽  
Vol 193 ◽  
pp. 04004
Author(s):  
Amlan Ray ◽  
A. K. Sikdar ◽  
D. Pandit ◽  
Sarmishtha Bhattacharyya ◽  
Soumik Bhattacharya ◽  
...  
Keyword(s):  
Direct Observation ◽  
Uncertainty Principle ◽  
Atomic Clock ◽  
Fluorescence Yield ◽  
Fission Event ◽  
Quantum Energy ◽  
X Ray ◽  
Time Uncertainty ◽  
The Mean

An atomic clock based on the measurement of the intrinsic width of K x-ray lines has been used to obtain evidence of long-lived fission of the highly excited plutonium nuclei produced in the fusion of 4He+238U at E(4He)Lab=60 MeV. The mean fission time of the long-lived fission could be obtained from the increase of the intrinsic width of plutonium K x-ray line using quantum energy-time uncertainty principle. The presence of long-lived fission (mean fission time >1×10-18 s) has been found and the fluorescence yield per fission event shows that most of the fission events are slow (~10-18 s).

Isomorphous replacement in electron diffraction of wet crystals of rat hemoglobin

1983 ◽  
Vol 41 ◽  
pp. 446-447
Author(s):  
William F. Tivol ◽  
Murray Vernon King ◽  
D. F. Parsons
Keyword(s):  
Electron Diffraction ◽  
Heavy Atom ◽  
Isomorphous Substitution ◽  
X Ray Diffraction ◽  
Salt Solutions ◽  
X Ray ◽  
Isomorphous Replacement ◽  
Structure Factors ◽  
Diffraction Structure ◽  
The Mean

Feasibility of isomorphous substitution in electron diffraction is supported by a calculation of the mean alteration of the electron-diffraction structure factors for hemoglobin crystals caused by substituting two mercury atoms per molecule, following Green, Ingram & Perutz, but with allowance for the proportionality of f to Z3/4 for electron diffraction. This yields a mean net change in F of 12.5%, as contrasted with 22.8% for x-ray diffraction.Use of the hydration chamber in electron diffraction opens prospects for examining many proteins that yield only very thin crystals not suitable for x-ray diffraction. Examination in the wet state avoids treatments that could cause translocation of the heavy-atom labels or distortion of the crystal. Combined with low-fluence techniques, it enables study of the protein in a state as close to native as possible.We have undertaken a study of crystals of rat hemoglobin by electron diffraction in the wet state. Rat hemoglobin offers a certain advantage for hydration-chamber work over other hemoglobins in that it can be crystallized from distilled water instead of salt solutions.

Long-period modulated superstructures in Pd-12.5 at.%Ce and Pd-15 at.%Ce alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 164-165
Author(s):  
Noriyuki Kuwano ◽  
Masaru Itakura ◽  
Kensuke Oki
Keyword(s):  
Electron Microscopy ◽  
Mean Value ◽  
Heavy Elements ◽  
Arc Furnace ◽  
X Ray ◽  
Long Period ◽  
Ultra High Purity ◽  
Heat Treated ◽  
Atomic Scattering ◽  
The Mean

Pd-Ce alloys exhibit various anomalies in physical properties due to mixed valences of Ce, and the anomalies are thought to be strongly related with the crystal structures. Since Pd and Ce are both heavy elements, relative magnitudes of (fcc-fpd) are so small compared with <f> that superlattice reflections, even if any, sometimes cannot be detected in conventional x-ray powder patterns, where fee and fpd are atomic scattering factors of Ce and Pd, and <f> the mean value in the crystal. However, superlattices in Pd-Ce alloys can be analyzed by electron microscopy, thanks to the high detectability of electron diffraction. In this work, we investigated modulated superstructures in alloys with 12.5 and 15.0 at.%Ce.Ingots of Pd-Ce alloys were prepared in an arc furnace under atmosphere of ultra high purity argon. The disc specimens cut out from the ingots were heat-treated in vacuum and electrothinned to electron transparency by a jet method.

Direct Observation of Monolayer Zones in Al-wt 4% Cu

1990 ◽  
Vol 48 (1) ◽  
pp. 14-15
Author(s):  
B. Jouffrey ◽  
D. Dorignac ◽  
A. Bourret
Keyword(s):  
Solid Solution ◽  
Synchrotron Radiation ◽  
Direct Observation ◽  
Supersaturated Solid Solution ◽  
Original Model ◽  
X Ray ◽  
Image Position

Since the early works on GP zones and the model independently proposed by Preston and Guinier on the first steps of precipitation in supersaturated solid solution of aluminium containing a few percent of copper, many works have been performed to understand the structure of different stages in the sequence of precipitation.The scheme which is generally admitted can be drawn from a work by Phillips.In their original model Guinier and Preston analysed a GP zone as composed of a single (100) copperrich plane surrounded by aluminum atomic planes with a slightly shorter distance from the original plane than in the solid solution.From X-ray measurements it has also been shown that GP1 zones were not only copper monolayer zones. They could be up to a few atomic planes thick. Different models were proposed by Guinier, Gerold, Toman. Using synchrotron radiation, proposals have been recently made.

Localization of calcium and zinc in the sperm storage tubules of chicken, quail and turkey using X-ray microanalysis

Reproduction ◽  
2000 ◽  
pp. 331-336 ◽  
Author(s):  
L Holm ◽  
H Ekwall ◽  
GJ Wishart ◽  
Y Ridderstrale
Keyword(s):  
Calcium Concentration ◽  
Sperm Storage ◽  
X Ray ◽  
Elemental Concentrations ◽  
Low Concentrations ◽  
Intracellular Content ◽  
Wet Weight ◽  
The Mean ◽  
Sperm Storage Tubules ◽  
Scanning Electron

Sperm storage tubules from the utero-vaginal junction of chickens, quails and turkeys were analysed for calcium and zinc using X-ray microanalysis of ultra-rapidly frozen tissue in a scanning electron microscope. This technique enabled the tubular fluid surrounding the stored spermatozoa and the intracellular content of the cells of the sperm storage tubules to be analysed separately and, by using standards with known concentrations, their elemental concentrations were estimated. The mean (+/- SEM) concentration of calcium in the tubular fluid from chickens, quails and turkeys was 17 +/- 3, 19 +/- 3 and 17 +/- 4 mmol kg(-1) wet weight, respectively. The intracellular calcium concentration of the cells of the tubules did not differ significantly from these values and was also similar in the mucosal epithelial cells of the utero-vaginal junction. Zinc was localized in the cells of turkey sperm storage tubules and tubular fluid, but at low concentrations. No zinc could be detected in corresponding structures from chickens and quails. The concentration of calcium in the tubular fluid is within the range known to inhibit the motility of spermatozoa, supporting this function for calcium during storage. Zinc is known to depress turkey sperm metabolism and it may also be involved in inducing quiescence of spermatozoa during storage in this species.

Use of the electro-separation method for improvement of the utility value of winter rapeseeds

2013 ◽  
Vol 27 (4) ◽  
pp. 419-424 ◽  
Author(s):  
S.J. Kovalyshyn ◽  
O.P. Shvets ◽  
S. Grundas ◽  
J. Tys
Keyword(s):  
Corona Discharge ◽  
Mechanical Damage ◽  
Edible Oil ◽  
Separation Method ◽  
Utility Value ◽  
X Ray ◽  
Winter Rapeseed ◽  
The Mean ◽  
Discharge Field ◽  
Prototype Apparatus

Abstract The paper presents the results of a study of the use of electro-separation methods for improvement of the utility value of 5 winter rapeseed cultivars. The process of electro-separation of rapeseed was conducted on a prototype apparatus built at the Laboratory of Application of Electro-technologies in Agriculture, Lviv National Agriculture University. The process facilitated separation of damaged, low quality seeds from the sowing material. The initial mean level of mechanically damaged seeds in the winter rapeseed cultivars studied varied within the range of 15.8-20.1%. Verification of the amount of seeds with mechanical damage was performed on X-ray images of seeds acquired by means of a digital X-ray apparatus. In the course of analysis of the X-ray images, it was noted that the mean level of mechanical damage to the seeds after the electro-separation was in the range of 2.1-3.8%. The application of the method of separation of rapeseeds in the corona discharge field yielded a significant reduction of the level of seeds with mechanical damage. The application of the method in practice may effectively contribute to improvement of the utility value of sowing material or seed material for production of edible oil.

scholarly journals Direct observation of the displacement field and microcracking in a glass by means of X-ray tomography during in situ Vickers indentation experiment

2019 ◽  
Vol 179 ◽  
pp. 424-433 ◽  
Author(s):  
Tanguy Lacondemine ◽  
Julien Réthoré ◽  
Éric Maire ◽  
Fabrice Célarié ◽  
Patrick Houizot ◽  
...  
Keyword(s):  
Direct Observation ◽  
Displacement Field ◽  
Vickers Indentation ◽  
X Ray ◽  
Indentation Experiment

scholarly journals Preparation of high-entropy carbides by different sintering techniques

2021 ◽  
Vol 56 (19) ◽  
pp. 11237-11247 ◽  
Author(s):  
Johannes Pötschke ◽  
Manisha Dahal ◽  
Mathias Herrmann ◽  
Anne Vornberger ◽  
Björn Matthey ◽  
...  
Keyword(s):  
Grain Size ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Vacuum Sintering ◽  
X Ray ◽  
High Entropy ◽  
Mean Grain Size ◽  
The Mean ◽  
Gas Pressure Sintering ◽  
Hardness Values

AbstractDense (Hf, Ta, Nb, Ti, V)C- and (Ta, Nb, Ti, V, W)C-based high-entropy carbides (HEC) were produced by three different sintering techniques: gas pressure sintering/sinter–HIP at 1900 °C and 100 bar Ar, vacuum sintering at 2250 °C and 0.001 bar as well as SPS/FAST at 2000 °C and 60 MPa pressure. The relative density varied from 97.9 to 100%, with SPS producing 100% dense samples with both compositions. Grain size measurements showed that the substitution of Hf with W leads to an increase in the mean grain size of 5–10 times the size of the (Hf, Ta, Nb, Ti, V,)C samples. Vacuum-sintered samples showed uniform grain size distribution regardless of composition. EDS mapping revealed the formation of a solid solution with no intermetallic phases or element clustering. X-ray diffraction analysis showed the structure of mostly single-phase cubic high-entropy carbides. Hardness measurements revealed that (Hf, Ta, Nb, Ti, V)C samples possess higher hardness values than (Ta, Nb, Ti, V, W)C samples.

scholarly journals AB0267 BODY COMPOSITION IN PATIENTS WITH RHEUMATOID ARTHRITIS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 1432.2-1432
Author(s):  
N. Toroptsova ◽  
O. Dobrovolskaya ◽  
N. Demin ◽  
L. Shornikova
Keyword(s):  
Rheumatoid Arthritis ◽  
Body Composition ◽  
Muscle Mass ◽  
Dual Energy ◽  
X Ray ◽  
T Score ◽  
Osteosarcopenic Obesity ◽  
The Mean ◽  
Total Fat ◽  
Appendicular Muscle Mass

Background:Rheumatoid arthritis (RA) is a complex inflammatory disease that modifies body composition. Using the dual-energy x-ray absorptiometry (DXA) in RA patients could be a method for body composition changes detection.Objectives:To study the body composition using DXA in patients with RA.Methods:The study involved 79 women with RA, median age 60 [55; 65] years. The bone mineral density (BMD) was measured by dual-energy x-ray absorptiometry using «Discovery A» (Hologic, USA). Assessment of body composition was carried out, using the program «Whole body». Sarcopenia (SP) was diagnosed as a decrease in appendicular mass index (AMI) <6.0 kg/m2. Osteoporosis (OP) was diagnosed as a decrease in T-score <-2.5 SD. Osteosarcopenia was determined when T-score was <-1.0 SD, AMI was <6.0 kg/m2, osteosarcopenic obesity - T-score was <-1.0 SD, AMI was <6.0 kg/m2and total fat was >35%.Results:The mean duration of RA was 9 [3; 11] years. The mean body mass index (BMI) was 27.6±4.8 kg/m2. Disease activity score in 28 joints-erythrocyte sedimentation rate was 4.5±1.3 points for the group. 39 (49.3%) patients used oral glucocorticoids continuously. Appendicular muscle mass and AMI were on average 17.8±3.0 kg and 6.8±1.0 kg/m2, respectively. AMI <6 kg/m2was detected in 20 (25.3%) patients. 56 (70.9%) women with RA had total fat > 35%, while only 22 (27.8%) of women with RA had obesity according to BMI (BMI >30 kg/m2). Isolated OP was found in 13 (16.5%), osteosarcopenia in 7 (8.9%) and osteosarcopenic obesity in 13 (16.5%) patients RA. No cases with isolated sarcopenia or sarcopenic obesity were detected. Only 3 (3.8%) patients did not have appendicular muscle mass, AMI and BMD decrease and overfat or obesity.Conclusion:About 97% women with RA had abnormal body composition phenotype: 16,5% - OP, 8.9% -osteosarcopenia, 16,5% - osteosarcopenic obesity and 54,4% - overfat.Disclosure of Interests:None declared

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