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Journal of Biomedical Physics &... Oct 2020I source is widely used in the treatment of hyperthyroidism and thyroid cancers. I emits both beta and gamma-rays. Radiation protection is considered for gamma rays...
BACKGROUND
I source is widely used in the treatment of hyperthyroidism and thyroid cancers. I emits both beta and gamma-rays. Radiation protection is considered for gamma rays emitted by I. It seems no special shield against I source to be designed.
OBJECTIVE
This research aims to evaluate determination of optimum shields in nuclear medicine against Tc and I sources by dosimetric method. Additionally, Monte Carlo simulation was used to find the optimum thickness of lead for protection against I source.
MATERIAL AND METHODS
This is an experimental research in the field of radiation protection. A calibrated model of GraetzX5C Plus dosimeter was used to measure exposure rates passing through the shields. The efficiency of the shields was evaluated against Tc and I. Furthermore, Monte Carlo simulation was used to find the optimum thickness of lead for protection against I source.
RESULTS
The findings of the dosimetric method show that the minimum and maximum efficiencies obtained by the lead apron with lead equivalent thickness of 0.25 mm and the syringe holder shields with thickness of 0.5 mm lead were 50.86% and 99.50%, respectively. The results of the simulations show that the minimum and maximum efficiencies obtained by lead thicknesses of 1 mm and 43 mm were 19.36% and 99.79%, respectively.
CONCLUSION
The optimum shields against Tc are the syringe holder shield, the tungsten syringe shield, and the lead partition, respectively. Furthermore, based on simulations, the thicknesses of 11-28 mm of lead with efficiencies between 90.6% to 99% are suggested as the optimum thicknesses to protect against I source.
PubMed: 33134225
DOI: 10.31661/jbpe.v0i0.1118 -
Journal of Feline Medicine and Surgery Aug 2021Adrenal gland size and its association with body weight have been rarely evaluated in cats. This study was undertaken to assess the association between feline body...
OBJECTIVES
Adrenal gland size and its association with body weight have been rarely evaluated in cats. This study was undertaken to assess the association between feline body weight and adrenal gland thickness, and to propose reference intervals (RIs) for adrenal gland thickness in healthy cats.
METHODS
This was a cross-sectional study in which 39 healthy cats were included. The cats were divided into two weight categories, classified as ⩽4.0 kg and >4-8 kg of ideal body weight (with 13 and 26 cats in each group, respectively), which took into consideration the body condition score of the cats. All cats underwent an ultrasound examination that was taken from a subcostal position. Maximum dorsoventral thicknesses of the left (MTL) and right (MTR) adrenal glands were measured in a sagittal plane. RIs were obtained for the maximum thickness (MT), which included the MTLs and MTRs of each cat. RIs with the 90% confidence intervals were calculated according to American Society for Veterinary Clinical Pathology guidelines on RIs.
RESULTS
No statistical differences for adrenal gland thickness were observed between the left and right ( = 0.543) adrenal glands or between male and female cats ( = 0.943). Mean MT was significantly greater in the group of cats weighing >4-8 kg compared with the group of cats weighing ⩽4 kg (3.7 ± 0.6 vs 3.2 ± 0.4 mm; <0.005). The lower limit of the RI for MT was 2.4 mm (range 2.2-2.6 mm) in the group weighing ⩽4 kg and 2.6 mm (range 2.4-2.8 mm) in the group weighing >4-8 kg. The upper limit of the RI for MT was 3.9 mm (range 3.7-4.1 mm) in the group of cats weighing ⩽4 kg and 4.8 mm (range 4.6-5.1 mm) in the group of cats weighing >4-8 kg.
CONCLUSIONS AND RELEVANCE
The use of RIs based on two group sizes allows for a more accurate ultrasonographic evaluation of adrenal gland thickness in cats. The maximum normal adrenal gland thickness is lower in smaller cats (3.9 mm for those weighing ⩽4 kg and 4.8 mm for those weighing >4-8 kg).
Topics: Adrenal Glands; Animals; Body Weight; Cats; Cross-Sectional Studies; Female; Male; Retrospective Studies; Ultrasonography
PubMed: 33236660
DOI: 10.1177/1098612X20974962 -
Materials (Basel, Switzerland) May 2022NEED-The effect of dimensional variability of sheet thickness (tolerance) and tool misalignment is poorly understood for the clinching process. Finite element analysis...
NEED-The effect of dimensional variability of sheet thickness (tolerance) and tool misalignment is poorly understood for the clinching process. Finite element analysis (FEA) is valuable but requires a lot of and is difficult to verify in this situation due to the asymmetrical geometry and nonlinear plasticity. OBJECTIVE-The objective of this work was to determine the effect of thickness tolerance, tool misalignment and sheet placement (top vs. bottom) in the clinching process, by use of analogue modelling with plasticine. METHOD-Experiments used a scaled-up punch and die, with plasticine as the analogue. Thickness tolerances were represented by sheet thicknesses of 11 and 7 mm, 12 and 8 mm, 8 and 12 mm and 13 and 9 mm for upper and lower sheets, respectively. Two types of lubricant were tested between sheets: glycerine and silicone oil. Angular variability was also introduced. Measured parameters were interlock (also called undercut) and neck thickness. Analogue results for deformation were compared with microscopy of metal clinching. FINDINGS-The results reveal that the multiscale analogue model is an efficient tool for studying the effect of dimensional deviation on a clinch joint. Thickness tolerance showed a critical relationship with interlock, namely a reduction to about half that of the nominal, for both maximum and least material conditions. Increased angular misalignment also reduced the interlock. Compared with glycerine, silicone oil tests showed reduced interlock, possibly the result of a lower coefficient of friction. ORIGINALITY-This work demonstrates the usefulness of analogue modelling for exploring process variability in clinching. The results also show that significant effects for sheet placement are ductility, lubricant (friction), thickness of samples and tool misalignment.
PubMed: 35629699
DOI: 10.3390/ma15103674 -
Medicine Aug 2022To determine the ultrasound imaging characteristics of patients with bronchial anthracofibrosis (BAF) and identify clinical markers for prevention and treatment. We...
To determine the ultrasound imaging characteristics of patients with bronchial anthracofibrosis (BAF) and identify clinical markers for prevention and treatment. We randomly selected 1243 participants (113 with BAF) who underwent bronchoscopy and received treatment at our institution between April 2018 and October 2019. BAF was classified as flat, deep-seated retracted, or black mucosal protruding based on microscopic findings. Ultrasound probes were used to determine the maximum thickness of the tube walls and submucosa. The average values of the submucosal and bony tissue areas in the BAF subtypes were compared. The BAF group included 13 participants with a history of tuberculosis (11.5%) and 57 participants with biofuel exposure (50.4%). The average exposure time was 17.4 ± 6.2 years; BAF accounted for 10% of the bronchoscopies performed. The maximum tube-wall thicknesses of the deep-seated retracted (17.3 ± 5.7) and black mucosal protruding (19.3 ± 5.4) groups were significantly greater than those of the flat group (12.5 ± 5.0; P < .05). The maximum thicknesses of the submucosa in the deep-retracted (9.8 ± 3.0) and black mucosal protruding (14.5 ± 5.0) groups were significantly greater than that of the flat group (6.6 ± 3.5; P < .05). The ratios of bone tissue in the flat and black mucosal protruding groups were 33.3 ± 9.3% and 34.9% ± 12.1%, respectively. The ratio in the deep-seated retracted group (65.2% ± 8.7%) was significantly reduced (P < .05). The flat group showed no significant change (P > .05). Differences in BAF airway remodeling among different subtypes may lead to varying clinical symptoms. Analyzing the characteristics of BAF airway remodeling and the regulatory pathway may provide new clues for treatment.
Topics: Airway Remodeling; Anthracosis; Bronchial Diseases; Bronchoscopy; Case-Control Studies; Humans; Ultrasonography
PubMed: 35984209
DOI: 10.1097/MD.0000000000030055 -
Indian Journal of Ophthalmology Oct 2019To record central corneal thickness and corneal diameter in preterm and term newborns within first week of their birth and in preterm neonates at term age.
PURPOSE
To record central corneal thickness and corneal diameter in preterm and term newborns within first week of their birth and in preterm neonates at term age.
METHODS
Babies born at ≤34 weeks of gestation period (n = 100), term babies who have a gestation period of >37 weeks (n = 100) and preterm neonates at term age (38-42 weeks) who were born at ≤34 weeks (n = 100) were included in this hospital based observational descriptive study. Corneal diameter was taken by Castroviejo Calipers. Central corneal thickness was measured using portable ultrasonic pachymeter (Pachette 3). Refractive status of the eyes was measured using streak Wellch Allyn retinoscope under cyclopentolate cycloplegia.
RESULTS
Measure of central corneal thickness and corneal diameter in preterm newborns was found to be 633.5 ± 2.8 μm and 8.1 ± 0.6 mm, in full term newborns it was 555.1 ± 2.7 μm and 9.5 ± 0.6 mm, and in preterm neonates at term age, it was 563.5 ± 2.5 μm and 9.6 ± 0.5 mm, respectively. Mean central corneal thickness was found to be more in preterm newborns 633.5 um then term newborns 555.1 um and the difference was statistically significant (P =0.001). Mean corneal diameter was found to be maximum (9.6 mm) in preterm neonates at term age.
CONCLUSION
Preterm babies have thick corneas and small corneal diameters. This study is useful with respect to the analysis of glaucoma in children and using preterm corneas as donor corneas in penetrating keratoplasty.
Topics: Birth Weight; Cornea; Female; Gestational Age; Humans; Infant, Newborn; Infant, Premature; Male; Organ Size; Retinoscopy; Term Birth
PubMed: 31546483
DOI: 10.4103/ijo.IJO_1988_18 -
Scientific Reports Nov 2022We present a co-axial acoustic-based optical coherence vibrometry probe (CoA-OCV) for vibro-acoustic resonance quantification in biological tissues. Sample vibrations...
We present a co-axial acoustic-based optical coherence vibrometry probe (CoA-OCV) for vibro-acoustic resonance quantification in biological tissues. Sample vibrations were stimulated via a loudspeaker, and pre-compensation was used to calibrate the acoustic spectrum. Sample vibrations were measured via phase-sensitive swept-source optical coherence tomography (OCT). Resonance frequencies of corneal phantoms were measured at varying intraocular pressures (IOP), and dependencies on Young´s Modulus (E), phantom thickness and IOP were observed. Cycling IOP revealed hysteresis. For E = 0.3 MPa, resonance frequencies increased with IOP at a rate of 3.9, 3.7 and 3.5 Hz/mmHg for varied thicknesses and 1.7, 2.5 and 2.8 Hz/mmHg for E = 0.16 MPa. Resonance frequencies increased with thickness at a rate of 0.25 Hz/µm for E = 0.3 MPa, and 0.40 Hz/µm for E = 0.16 MPa. E showed the most predominant impact in the shift of the resonance frequencies. Full width at half maximum (FWHM) of the resonance modes increased with increasing thickness and decreased with increasing E. Only thickness and E contributed to the variance of FWHM. In rabbit corneas, resonance frequencies of 360-460 Hz were observed. The results of the current study demonstrate the feasibility of CoA-OCV for use in future OCT-V studies.
Topics: Animals; Rabbits; Acoustics; Intraocular Pressure; Tomography, Optical Coherence; Vibration
PubMed: 36336702
DOI: 10.1038/s41598-022-21978-8 -
PloS One 2020To investigate the corneal epithelial thickness topography with optical coherence tomography (OCT) and its relationship with vision quality in epithelial basement... (Observational Study)
Observational Study
PURPOSE
To investigate the corneal epithelial thickness topography with optical coherence tomography (OCT) and its relationship with vision quality in epithelial basement membrane dystrophy (EBMD).
METHODS
45 eyes of EBMD patients, 26 eyes of dry eye (DED) patients and 22 eyes of normal subjects were enrolled. All participants were subjected to 9-mm corneal epithelial mapping with OCT and vision quality was assessed with the optical quality analysis system using the objective scatter index (OSI). Central, superior, inferior, minimum, maximum, and standard deviation of epithelium thickness (Irregularity), were analysed and correlations with the OSI were calculated.
RESULTS
The mean (±SD) central, inferior and maximum epithelial thicknesses of the EBMD patients (respectively, 56.4 (±8.1) μm, 58.9 (±6.4) μm, and 67.1 (±8.3) μm) were thicker compared to DED patients (P<0.05) and normal subjects (P<0.05). We found greater irregularity of epithelial thickness in EBMD (5.1±2.5 μm) compared to DED patients (2.6±1.0 μm) (P = 4.4.10-6) and normal subjects (2.1±0.7 μm) (P = 7.6.10-7). The mean OSI was worse in EBMD patients than in DED patients (P = 0.01) and compared to normal subjects (P = 0.02). The OSI correlated with the epithelial thickness irregularity (Spearman coefficient = 0.54; P = 2.65.10-5).
CONCLUSIONS
The OCT pachymetry map demonstrated that EBMD patients had thicker corneal epithelium in the central and inferior region. These changes were correlated with objective measurements of vision quality. This OCT characterisation of the EMBD provides a better understanding of the epithelial behaviour in this dystrophy and its role in vision quality.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Basement Membrane; Cogan Syndrome; Cornea; Corneal Pachymetry; Corneal Topography; Cross-Sectional Studies; Dry Eye Syndromes; Epithelium, Corneal; Female; Fourier Analysis; Humans; Keratoconus; Male; Middle Aged; Tomography, Optical Coherence; Young Adult
PubMed: 33237913
DOI: 10.1371/journal.pone.0239124 -
The New England Journal of Medicine Jul 2011Intima-media thickness of the walls of the common carotid artery and internal carotid artery may add to the Framingham risk score for predicting cardiovascular events.
BACKGROUND
Intima-media thickness of the walls of the common carotid artery and internal carotid artery may add to the Framingham risk score for predicting cardiovascular events.
METHODS
We measured the mean intima-media thickness of the common carotid artery and the maximum intima-media thickness of the internal carotid artery in 2965 members of the Framingham Offspring Study cohort. Cardiovascular-disease outcomes were evaluated for an average follow-up of 7.2 years. Multivariable Cox proportional-hazards models were generated for intima-media thickness and risk factors. We evaluated the reclassification of cardiovascular disease on the basis of the 8-year Framingham risk score category (low, intermediate, or high) after adding intima-media thickness values.
RESULTS
A total of 296 participants had a cardiovascular event. The risk factors of the Framingham risk score predicted these events, with a C statistic of 0.748 (95% confidence interval [CI], 0.719 to 0.776). The adjusted hazard ratio for cardiovascular disease with a 1-SD increase in the mean intima-media thickness of the common carotid artery was 1.13 (95% CI, 1.02 to 1.24), with a nonsignificant change in the C statistic of 0.003 (95% CI, 0.000 to 0.007); the corresponding hazard ratio for the maximum intima-media thickness of the internal carotid artery was 1.21 (95% CI, 1.13 to 1.29), with a modest increase in the C statistic of 0.009 (95% CI, 0.003 to 0.016). The net reclassification index increased significantly after addition of intima-media thickness of the internal carotid artery (7.6%, P<0.001) but not intima-media thickness of the common carotid artery (0.0%, P=0.99). With the presence of plaque, defined as intima-media thickness of the internal carotid artery of more than 1.5 mm, the net reclassification index was 7.3% (P=0.01), with an increase in the C statistic of 0.014 (95% CI, 0.003 to 0.025).
CONCLUSIONS
The maximum internal and mean common carotid-artery intima-media thicknesses both predict cardiovascular outcomes, but only the maximum intima-media thickness of (and presence of plaque in) the internal carotid artery significantly (albeit modestly) improves the classification of risk of cardiovascular disease in the Framingham Offspring Study cohort. (Funded by the National Heart, Lung, and Blood Institute.).
Topics: Aged; Cardiovascular Diseases; Carotid Artery, Common; Cohort Studies; Female; Humans; Kaplan-Meier Estimate; Male; Middle Aged; Probability; Proportional Hazards Models; Risk Assessment; Risk Factors; Tunica Intima; Tunica Media; Ultrasonography
PubMed: 21774709
DOI: 10.1056/NEJMoa1012592 -
Materials (Basel, Switzerland) May 2023Ultra-high-performance concrete (UHPC) has greater mechanical and durability performance than normal concrete (NC). Using a limited dosage of UHPC on the external...
Ultra-high-performance concrete (UHPC) has greater mechanical and durability performance than normal concrete (NC). Using a limited dosage of UHPC on the external surface of NC to form a gradient structure could significantly improve the strength and corrosion resistance of the concrete structure and avoid the problems caused by bulk UHPC. In this work, white ultra-high-performance concrete (WUHPC) was selected as an external protection layer for normal concrete to construct the gradient structure. WUHPC of different strengths were prepared, and 27 gradient WUHPC-NC specimens with different WUHPC strengths and interval times of 0, 10, and 20 h were tested using splitting tensile strength to reveal the bonding properties. Fifteen prism gradient specimens with the size of 100 × 100 × 400 mm and a WUHPC ratio of 1:1, 1:3, and 1:4 were tested using the four-pointed bending method to study the bending performance of the gradient concrete with different WUHPC thicknesses. Finite element models with different WUHPC thicknesses were also built to simulate the cracking behaviors. The results showed that the bonding properties of WUHPC-NC were stronger with less interval time and reached the maximum of 1.5 MPa when the interval was 0 h. Moreover, the bond strength first increased and then decreased with the decline in the strength gap between WUHPC and NC. When the thickness ratios of WUHPC to NC were 1:4, 1:3, and 1:1, the flexural strength of the gradient concrete improved by 89.82%, 78.80%, and 83.31%, respectively. The major cracks rapidly propagated from the 2 cm position to the bottom of the mid-span, and the thickness of 1:4 was the most efficient design. The results simulated by finite element analysis also proved that the elastic strain at the crack propagating point was the minimum and was easier to crack. The simulated results were in good accordance with the experimental phenomenon.
PubMed: 37241251
DOI: 10.3390/ma16103625 -
Materials (Basel, Switzerland) Mar 2023Cobalt Iron Yttrium (CoFeY) magnetic film was made using the sputtering technique in order to investigate the connection between the thickness and annealing procedures....
Cobalt Iron Yttrium (CoFeY) magnetic film was made using the sputtering technique in order to investigate the connection between the thickness and annealing procedures. The sample was amorphous as a result of an insufficient thermal driving force according to X-ray diffraction (XRD) examination. The maximum low-frequency alternate-current magnetic susceptibility (χ) values were raised in correlation with the increased thickness and annealing temperatures because the thickness effect and Y addition improved the spin exchange coupling. The best value for a 50 nm film at annealing 300 °C for χ was 0.20. Because electron carriers are less constrained in their conduction at thick film thickness and higher annealing temperatures, the electric resistivity and sheet resistance are lower. At a thickness of 40 nm, the film's maximum surface energy during annealing at 300 °C was 28.7 mJ/mm. This study demonstrated the passage of photon signals through the film due to the thickness effect, which reduced transmittance. The best condition was found to be 50 nm with annealing at 300 °C in this investigation due to high χ, strong adhesion, and low resistivity, which can be used in magnetic fields.
PubMed: 36984370
DOI: 10.3390/ma16062490