An Investigation of Uranium L-Edges of Metamict and Annealed Betafite

1985 ◽  
Vol 50 ◽  
Author(s):  
R. B. Greegor ◽  
F. W. Lytle ◽  
B. C. Chakoumakos ◽  
G. R. Lumpkin ◽  
R. C. Ewing
Keyword(s):  
Nearest Neighbor ◽  
X Ray ◽  
Bond Lengths ◽  
Waste Forms ◽  
Naturally Occurring ◽  
Pyrochlore Group ◽  
Group A ◽  
Group B ◽  
X Ray Absorption ◽  
Metamict Minerals

AbstractThe uranium site in naturally occurring metamict minerals of the pyrochlore group (A1–2B2O6Y0–1) has been investigated using x-ray absorption spectroscopy (XAS). Pyrochlore structures are common phases in proposed polycrystalline waste forms. Betafite, a member of the pyrochlore group (B = 2Ti ≥ Nb+Ta), exhibits U-O bond lengths of 1.94 and 2.37 A for the metamict state, and 2.03 and 2.51 A for the crystalline (annealed) state. The U-O bond lengths decrease (∼0.1 A) and there is a disruption in the second nearest neighbor periodicidy as material is converted from the crystalline to the metamict state.

scholarly journals Exafs Spectroscopic Studies of Uranium (VI) Oxide Precipitates

1996 ◽  
Vol 432 ◽  
Author(s):  
P.G. Allen ◽  
D.K. Shuh ◽  
J.J. Bucher ◽  
N.M. Edelstein ◽  
C.E.A. Palmer ◽  
...  
Keyword(s):  
Room Temperature ◽  
Nearest Neighbor ◽  
Spectroscopic Studies ◽  
X Ray ◽  
Bond Lengths ◽  
Curve Fitting Analysis ◽  
Low Ionic Strength ◽  
X Ray Absorption ◽  
Oxygen Bond ◽  
Precipitate Structure

AbstractWe have investigated the structures of U(VI) oxides precipitated from room temperature aqueous solutions at low ionic strength as a function of pH. Using the uranium LIII - edge extended x-ray absorption fine structure (EXAFS) as a probe of the local structure around the uranium, a trend is observed whereby the axial oxygen bond lengths from the uranyl groups increase from 1.80 Å at pH=7 to 1.86 Å at pH=11. A concomitant decrease in the equatorial oxygen and nearest-neighbor uranium bond lengths also occurs with increasing pH. Expansion of the linear O=U=O group is seen directly at the L111 absorption edge where multiple scattering resonances systematically shift in energy. EXAFS curve-fitting analysis on these precipitates and a sample of synthetic schoepite indicate that the structure of the species formed at pH=7 is similar to the structure of schoepite. At pH=11, the precipitate structure is similar to that of a uranate.

scholarly journals Effect of germanium auto-diffusion on the bond lengths of Ga and P atoms in GaP/Ge(111) investigated by using X-ray absorption spectroscopy

2021 ◽  
Vol 28 (2) ◽  
pp. 480-489
Author(s):  
R. Roychowdhury ◽  
P. Rajput ◽  
Shailendra Kumar ◽  
R. Kumar ◽  
A. Bose ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Residual Strain ◽  
Tensile Strain ◽  
Nearest Neighbor ◽  
Secondary Ion Mass Spectrometry ◽  
Nearest Neighbors ◽  
X Ray ◽  
Bond Lengths ◽  
Out Of Plane ◽  
X Ray Absorption

The germanium auto-diffusion effects on the inter-atomic distance between the nearest neighbors of the Ga atom in GaP epilayers are investigated using high-resolution X-ray diffraction (HRXRD) and X-ray absorption spectroscopy. The GaP layers grown on Ge (111) are structurally coherent and relaxed but they show the presence of residual strain which is attributed to the auto-diffusion of Ge from the results of secondary ion mass spectrometry and electrochemical capacitance voltage measurements. Subsequently, the inter-atomic distances between the nearest neighbors of Ga atom in GaP are determined from X-ray absorption fine-structure spectra performed at the Ga K-edge. The estimated local bond lengths of Ga with its first and second nearest neighbors show asymmetric variation for the in-plane and out-of-plane direction of GaP/Ge(111). The magnitude and direction of in-plane and out-of-plane microscopic residual strain present in the GaP/Ge are calculated from the difference in bond lengths which explains the presence of macroscopic residual tensile strain estimated from HRXRD. Modified nearest neighbor configurations of Ga in the auto-diffused GaP epilayer are proposed for new possibilities within the GaP/Ge hetero-structure, such as the conversion from indirect to direct band structures and engineering the tensile strain quantum dot structures on (111) surfaces.

scholarly journals The Impact of Left Atrial Size in Catheter Ablation of Atrial Fibrillation Using Remote Magnetic Navigation

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Xiao-yu Liu ◽  
Hai-feng Shi ◽  
Jie Zheng ◽  
Ku-lin Li ◽  
Xiao-xi Zhao ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Catheter Ablation ◽  
Left Atrial ◽  
Magnetic Navigation ◽  
Remote Magnetic Navigation ◽  
X Ray ◽  
Group A ◽  
Group B ◽  
The Impact

Objective. The objective of this study was to investigate the impact of left atrial (LA) size for the ablation of atrial fibrillation (AF) using remote magnetic navigation (RMN). Methods. A total of 165 patients with AF who underwent catheter ablation using RMN were included. The patients were divided into two groups based on LA diameter. Eighty-three patients had small LA (diameter <40 mm; Group A), and 82 patients had a large LA (diameter ≥40 mm; Group B). Results. During mapping and ablation, X-ray time (37.0 (99.0) s vs. 12 (30.1) s, P<0.001) and X-ray dose (1.4 (2.7) gy·cm2 vs. 0.7 (2.1) gy·cm2, P=0.013) were significantly higher in Group A. No serious complications occurred in any of the patients. There was no statistical difference in the rate of first anatomical attempt of pulmonary vein isolation between the two groups (71.1% vs. 57.3%, P=0.065). However, compared with Group B, the rate of sinus rhythm was higher (77.1% vs. 58.5%, P<0.001) during the follow-up period. More patients in Group A required a sheath adjustment (47/83 vs. 21/82, P<0.001), presumably due to less magnets positioned outside of the sheath. In vitro experiments with the RMN catheter demonstrated that only one magnet exposed created the sheath affects which influenced the flexibility of the catheter. Conclusions. AF ablation using RMN is safe and effective in both small and large LA patients. Patients with small LA may pose a greater difficulty when using RMN which may be attributed to the fewer magnets beyond the sheath. As a result, the exposure of radiation was increased. This study found that having at least two magnets of the catheter positioned outside of the sheath can ensure an appropriate flexibility of the catheter.

scholarly journals Technetium Speciation in Cement Waste Forms Determined by X-ray Absorption Fine Structure Spectroscopy

1997 ◽  
Vol 76 (1-2) ◽  
Author(s):  
P. G. Allen ◽  
G. S. Siemering ◽  
D. K. Shuh ◽  
J. J. Bucher ◽  
N. M. Edelstein ◽  
...  
Keyword(s):  
Fine Structure ◽  
X Ray ◽  
Absorption Fine ◽  
Waste Forms ◽  
X Ray Absorption

Repairing Rabbit Radius Bone Defects with Simvastatin Compound Biological Bone

2021 ◽  
Vol 11 (7) ◽  
pp. 1263-1270
Author(s):  
Zhong-Yu Liu ◽  
Jin-Li Zhang ◽  
Yang Zhang ◽  
Shi-Lian Kan ◽  
Jun Liang ◽  
...  
Keyword(s):  
Bone Defect ◽  
Maximum Stress ◽  
Biomechanical Testing ◽  
Bone Defects ◽  
Bending Test ◽  
Bone Material ◽  
X Ray ◽  
Group A ◽  
Group B ◽  
Group D

Objective: This study aimed to investigate the feasibility of repairing rabbit radius bone defects with simvastatin compound biological bone. Methods: Simvastatin biological bone material was prepared, and osteoblasts were cultured. A total of 42 New Zealand white rabbits were randomly divided into four groups, and a bone defect with a length of 15 mm was created at the middle part of the radial shaft of both limbs in each rabbit, thereby establishing a bone defect model. The grafts in group A were biological bones of osteoblasts combined with simvastatin; the grafts in group B were biological bones of simvastatin; the grafts in group C were biological compound bones of osteoblasts; and the grafts in group D were simple biological bones. In each group, four animals were randomly sacrificed at the sixth and twelfth week after surgery, and specimens were collected for gross observation, X-ray examination, histological observation, and biomechanical testing. In each group, two animals were randomly sacrificed at the twelfth week after surgery; a three-point bending test was performed using a biomechanical testing machine, and the results were compared with those of a normal radius. Results: The X-ray and histological examinations at 6 and 12 weeks after surgery revealed that the osteogenesis ability of the simvastatin biological bone and osteoblast-simvastatin biological bone was better than that of the osteoblast biological bone and simple biological bone, which was superior in group A and group B to group C and group D. The results of the biomechanical examination revealed that the maximum stress of the normal radius was significantly higher than that of the experimental groups. Among the experimental groups, the difference between group A and group B was not statistically significant, and the maximum stress was higher in groups A and B than in groups C and D. Conclusion: Simvastatin biological bone material can promote the repair of rabbit radius defects and increase the quality of bone healing.

scholarly journals Bracket base remnants after orthodontic debonding

2013 ◽  
Vol 83 (5) ◽  
pp. 885-891 ◽  
Author(s):  
Matteo Zanarini ◽  
Antonio Gracco ◽  
Monica Lattuca ◽  
Silvia Marchionni ◽  
Maria Rosaria Gatto ◽  
...  
Keyword(s):  
Energy Dispersive ◽  
Scanning Electron Micrographs ◽  
X Ray ◽  
Significant Difference ◽  
Group A ◽  
Fixed Appliances ◽  
Group B ◽  
Imagej Software ◽  
Bracket Base ◽  
Scanning Electron

ABSTRACT Objective: To evaluate whether the debonding procedure leads to restitutio ad integrum of the enamel surface by investigating the presence of enamel within the bracket base remnants after debonding. Materials and Methods: Sixty patients who completed orthodontic treatment with fixed appliances were included. A total of 1068 brackets were microphotographed; the brackets presenting some remnants on the base (n  =  818) were selected and analyzed with ImageJ software to measure the remnant area. From this population a statistically significant sample (n  =  100) was observed under a scanning electron microscope to check for the presence of enamel within the remnants. Energy dispersive x-ray spectrometry was also performed to obtain quantitative data. Results: Statistically significant differences in the remnant percentage between arches were observed for incisor and canine brackets (P &lt; .0001 and P  =  .022, respectively). From a morphologic analysis of the scanning electron micrographs the bracket bases were categorized in 3 groups: group A, bases presenting a thin enamel coat (83%); group B, bases showing sizable enamel fragments (7%); group C, bases with no morphologic evidence of enamel presence (10%). Calcium presence was noted on all evaluated brackets under energy dispersive x-ray spectrometry. No significant difference was observed in the Ca/Si ratio between group A (16.21%) and group B (18.77%), whereas the Ca/Si ratio in group C (5.40%) was significantly lower than that of the other groups (P &lt; .323 and P  =  .0001, respectively). Conclusion: The objective of an atraumatic debonding is not achieved yet; in some cases the damage could be clinically relevant.

scholarly journals BMSCs Seeding in Different Scaffold Incorporation with Hyperbaric Oxygen Treat Seawater Immersed Bony Defect

2021 ◽  
Author(s):  
gan zhang ◽  
Xiaosong Chen ◽  
Xunsheng Cheng ◽  
Xiuwu Ma ◽  
Congcong Chen
Keyword(s):  
Bone Formation ◽  
Bone Defect ◽  
Medullary Canal ◽  
Bony Defect ◽  
New Bone Formation ◽  
X Ray ◽  
New Zealand White Rabbits ◽  
Group A ◽  
Group B ◽  
Group D

Abstract Introduction: The experiment was undertaken to estimate the effect of BMSCs seeding in different scaffold incorporation with HBO on the repair of seawater immersed bone defect. And future compared n-HA/PLGA with β-TCP/PLGA as scaffold in treatment effect of seawater immersed bone defect.Methods: 60 New Zealand White rabbits with standard seawater defect in radius were randomly divided to group A (implant with nothing), group B (implanted with atuogenous bone), group C (implanted with n-HA/PLGA/BMSCs, and Group D ( implanted with β-TCP/PLGA/BMSCs). After implant, each rabbit receive HBO treatment at 2.4 ATA 100% oxygen for 120 minutes per day for 2 weeeks. Radiograph, histological and biomechanical examination were used to analyze osteogenesis.Result: X-ray analysis show that n-HA/PLGA/BMSCs and β-TCP/PLGA/BMSCs could accelerate the new bone formation, and the new bone formation in group C was lager than in group D or group A, and close to group B (P<0.05). After 12 weeks, in group A, defect without scaffold show a loose connect tissue filled in the areas. The medullary canal in group B was recanalizated. Defect in group C and D show a larger number of wove bone formation. The new wove bone formation in defect areas in group C was lager than D. The mechanical examination revealed ultimate strength at 12 weeks were group D>group C>group B>group A(P<0.05).Conclusion: Scaffold of n-HA/PLGA and β-TCP/PLGA incorporation with HBO and BMSCs were effective to treat seawater immersed bone defect, and n-HA/PLGA was more excellent than β-TCP/PLGA.

scholarly journals Comparison of Different Diagnostic Method for Mycobacteria Tuberculosis in Suspected Patients

1970 ◽  
Vol 7 (2) ◽  
pp. 84-88
Author(s):  
AR Khagi ◽  
S Singh ◽  
S Subba ◽  
A Bajracharya ◽  
R Tuladhar ◽  
...  
Keyword(s):  
Comparative Study ◽  
Sputum Smear ◽  
Study Group ◽  
Bacterial Cells ◽  
X Ray ◽  
Smear Examination ◽  
Group A ◽  
Chest X Ray ◽  
Group B ◽  
Sputum Smear Examination

Background: Microbial examination of smear of AFB by Z-N stain is currently the most rapid method for the detection of M. tuberculosis but its sensitivity is low i.e. required at least 10,000 bacterial cells per ml of sputum and also none specific, but auramine staining method has higher sensitivity than that of the Z-N stain but there are chances of false positive. Objective of this study was to find the correlation between chest X-ray, direct sputum smear examination by Ziehl-Neelsen stain, Auramine fluorochrome stain and sputum culture for M. tuberculosis. Methods: During that study period 250 x 3 samples were taken three each from 250 patients and divided into two groups A and B by performing Auramine fluorochrome stain in all samples . In group A, there were 150 fluorochrome stain positive samples. One each from 150 patient for comparative study of direct sputum smear examination by Ziehl-Neelsen stain, , culture on LJ medium and chest X-ray. Similarly in group B, next 100 fluorochrome stain negative specimens one each from 100 patients were taken for the comparative study of direct sputum smear examination by Ziehl-Neelsen stain, culture and chest X-ray. Results: In the study group A (n=150) all the specimens were positive in Auramine fluorochrome stain and all of them show positive in X-ray but only 134 showed positive in Ziehl-Neelsen stain and 136 showed positive in culture. In the study group B (n=100), all the specimens were negative in Auramine fluorochrome stain and all of them show negative in Ziehl-Neelsen stain but 14 of them were positive in culture and 24 were positive in chest X-ray. Conclusions: The diagnosis of PTB could be made by Auramine fluorochrome microscopy and culture. Key words: auramine fluorochrome stain; culture; mycobacterium tuberculosis; x-ray; ziehl-neelsen. DOI: 10.3126/jnhrc.v7i2.3012 Journal of Nepal Health Research Council Vol.7(2) Apr 2009 84-88

scholarly journals CLINICAL STUDY ON SHIREESHADI AVAPEEDANA NASYA IN THE MANAGEMENT OF SURYAVARTHA (FRONTAL SINUSITIS)

2021 ◽  
Vol 9 (8) ◽  
pp. 1654-1658
Author(s):  
Amarnath H K
Keyword(s):  
Clinical Study ◽  
Economic Status ◽  
Age Groups ◽  
Frontal Sinusitis ◽  
Nasal Blockage ◽  
X Ray ◽  
Group A ◽  
Foul Smell ◽  
Group B ◽  
Clinical Conditions

Nasya karma is considered a prime treatment modality in all types of Shiroroga (Headache) and also in Suryavar- tha (Frontal Sinusitis). Suryavartha (Frontal Sinusitis) is one of the 11 types of Shiroroga. It is one of the com- mon clinical conditions found in day to day general as well as Shalakya (ENT) practice. It presents with headache as one of its cardinal features and its occurrence is found in both genders and in all age groups. Objective: To study the efficacy of Shireeshadi Avapeedana Nasya in the management of Suryavartha (Frontal Sinusitis). Ma- terial methods: Twenty patients of Suryavartha (Frontal Sinusitis) were diagnosed and registered for the clinical study irrespective of sex, socio-economic status, and religion. The study was divided into two groups - Group A and Group B. Group – A patients were treated with Shireeshadi Avapeedana Nasya for 7 days and Group – B patients were treated by Nasya with milk for 7 days. Observation and result: Among 20 patients of Suryavartha / frontal sinusitis, 20 (100%) of patients had headache, 11 (55%) had nasal blockage, 05 (25%) had nasal dis- charge, 08 (40%) had foul smell in their breath and 14 (70%) have variations from normal X-Ray. The severity of headache is significantly reduced after treatment in both Groups A and B (92.95% and 73.07%) respectively. Conclusion: Administration of Shireeshadi Avapeeda Nasya showed statistically significant improvement in the management of Suryavartha (Frontal Sinusitis). Keywords: Suryavartha, Nasya, Shireeshadi Avapeedana Nasya, Frontal Sinusitis, Shigru, Mulaka, Ksheera.

scholarly journals X-Ray and Near-Infrared Spectroscopy of Dim X-Ray Point Sources Constituting the Galactic Ridge X-Ray Emission

2014 ◽  
Vol 1 (1) ◽  
pp. 222-226
Author(s):  
Kumiko Morihana ◽  
Masahiro Tsujimoto ◽  
Ken Ebisawa
Keyword(s):  
Near Infrared ◽  
Cataclysmic Variables ◽  
Point Sources ◽  
X Ray ◽  
Nir Imaging ◽  
Group A ◽  
Field L ◽  
Imaging And Spectroscopy ◽  
Group B ◽  
Thermal Sources

We present the results of X-ray and Near-Infrared observations of the Galactic Ridge X-ray Emission (GRXE). We extracted 2,002 X-ray point sources in the <em>Chandra</em> Bulge Field (l =0°.113, b = 1°.424) down to ~10<sup>-14.8</sup> ergscm<sup>-2</sup>s<sup>-1</sup> in 2-8 keV band with the longest observation (900 ks) of the GRXE. Based on X-ray brightness and hardness, we classied the X-ray point sources into three groups: A (hard), B (soft and broad spectrum), and C (soft and peaked spectrum). In order to know populations of the X-ray point sources, we carried out NIR imaging and spectroscopy observation. We identied 11% of X-ray point sources with NIR and extracted NIR spectra for some of them. Based on X-ray and NIR properties, we concluded that non-thermal sources in the group A are mostly active galactic nuclei and the thermal sources are mostly white dwarf binaries such as cataclysmic variables (CVs) and Pre-CVs. We concluded that the group B and C sources are X-ray active stars in flare and quiescence, respectively.

Sign in / Sign up

Export Citation Format

Share Document