102 research outputs found
Investigation of the Drawability of Sheet Metals (Measurements of r Values of Sheet Steel)
For assessing the qualities of sheet metal for deep-drawing by the tension test, γ value is adopted generally. However, it is difficult and complicated to obtain the precise value of it. In order to obtain the value precisely and easily, the authors have made trialy the devices to measure directly the elongation and the reductions of width and thickness; these devices are transducers to which the electrical resistance strain gauges are applied. By using these devices, precise, continuous, multipoint and quick measurement can be done. It has been clarified by the continuous measurements that γ values are not the same relating to the elongations. It is recommended that one uses γ value obtained at about 25% elongation
トルコ、アナトリア高原、トゥズ湖とコンヤ盆地における過去24,000年間の湖水位変動と扇状地の形成
Alluvial fans developed and lake levels fluctuated several times according to the climatic changes during the last 24,000 years. Alluvial fans developed in Lake Tuz in the cold, pluvial periods of increasing discharge during the Holocene around 5000 yr BP. and after 3500 yr BP. Lake expansion occurred at 23 ka., 18-20 ka., 14-15 ka., and 11ka. over the last 24,000 years in the Konya Basin. These expansions, shown by the raised lake terraces and beach ridges, were mainly due to cold and pluvial climatic changes. The lake level rose in the colder climate during marine oxygen isotope stage 2 and the Younger Dryas period. The lake level reached its highest level of 1013 to 1014 m during the last Glacial maximum before 18 ka
RGD targeting of human ferritin iron oxide nanoparticles can enhance in vivo carotid MRI of experimental atherosclerosis
Assessment of Elastase-Induced Murine Abdominal Aortic Aneurysms: Comparison of Ultrasound Imaging with In Situ Video Microscopy
Aims. The aim of this study was to definitively assess the validity of noninvasive high-frequency ultrasound (US) measurements of aortic luminal diameter (ALD) in a murine model of elastase-induced abdominal aortic aneurysm in comparison with in situ video microscopy (VM).
Methods. C57BL/6 mice underwent transient perfusion of the aorta with either elastase (n = 20: Elastase group) or saline (n = 10: Sham). Unoperated mice (n = 10) were also studied. Results. ALD measurements by US had excellent linear correlation and absolute agreement with that by VM in both Control (unoperated or sham-operated mice) and elastase groups (r = 0.96, intraclass correlation coefficient (ICC) = 0.88 and r = 0.93, ICC = 0.92, resp.). Bland-Altman analysis of US compared with VM measurements in both groups indicated good agreement, however US measurements were slightly but significantly higher than VM measurements in the control group (mean bias 0.039 mm, P < .05). Linear regression analysis revealed excellent correlation between US and VM measurements in both groups. (R2 = 0.91 in Control group, R2 = 0.85 in elastase group.) The reliability of US measurements was also confirmed by ex vivo histological measurements. Conclusions. High-frequency US provides reliable ALD measurements in developing murine abdominal aortic aneurysms
Association Between Visceral Adipose Tissue Area and Coronary Plaque Morphology Assessed by CT Angiography
ObjectivesWe sought to investigate the association between visceral adipose tissue (VAT) with the presence, extent, and characteristics of noncalcified coronary plaques (NCPs) using 64-slice computed tomography angiography (CTA).BackgroundAlthough visceral adiposity is associated with cardiovascular events, its association with NCP burden and vulnerability is not well known.MethodsThe study population consisted of 427 patients (age 67 ± 11 years; 63% men) with proven or suspected coronary artery disease who underwent 64-slice CTA. We assessed the presence and number of NCPs for each patient. The extent of NCP was tested for the difference between high (≥2) and low (≤1) counts. We further evaluated the vulnerable characteristics of NCPs with positive remodeling (remodeling index >1.05), low CT density (≤38 HU), and the presence of adjacent spotty calcium. Plain abdominal scans were also performed to measure the VAT and subcutaneous adipose tissue area.ResultsA total of 260 (61%) patients had identifiable NCPs. Multivariate analyses revealed that increased VAT area (per 1 standard deviation, 58 cm2) was significantly associated with both the presence (odds ratio [OR]: 1.68; 95% confidence interval [CI]: 1.28 to 2.22) and extent (OR: 1.31; 95% CI: 1.03 to 1.68) of NCP. Other body composition measures, including subcutaneous adipose tissue area, body mass index, and waist circumference were not significantly associated with either presence or extent of NCP. Increased VAT area was also independently associated with the presence of NCP with positive remodeling (OR: 1.71; 95% CI: 1.18 to 2.53), low CT density (OR: 1.69; 95% CI: 1.17 to 2.47), and adjacent spotty calcium (OR: 1.52; 95% CI: 1.03 to 2.27).ConclusionsIncreased VAT area was significantly associated with NCP burden and vulnerable characteristics identified by CTA. Our findings may explain the excessive cardiovascular risk in patients with visceral adiposity, and support the potential role of CTA to improve risk stratification in such patients
Gd-based protein cage nanoparticles provide enhanced r1 relaxivity and detect experimental atherosclerosis
Characterization of Noncalcified Coronary Plaques and Identification of Culprit Lesions in Patients With Acute Coronary Syndrome by 64-Slice Computed Tomography
ObjectivesWe sought to characterize noncalcified coronary atherosclerotic plaques in culprit and remote coronary atherosclerotic lesions in patients with acute coronary syndrome (ACS) with 64-slice computed tomography (CT).BackgroundLower CT density, positive remodeling, and adjacent spotty coronary calcium are characteristic vessel changes in unstable coronary plaques.MethodsOf 147 consecutive patients who underwent contrast-enhanced 64-slice CT examination for coronary artery visualization, 101 (ACS; n = 21, non-ACS; n = 80) having 228 noncalcified coronary atherosclerotic plaques (NCPs) were studied. Each NCP detected within the vessel wall was evaluated by determining minimum CT density, vascular remodeling index (RI), and morphology of adjacent calcium deposits.ResultsThe CT visualized more NCPs in ACS patients (65 lesions, 3.1 ± 1.2/patient) than in non-ACS patients (163 lesions, 2.0 ± 1.1/patient). Minimum CT density (24 ± 22 vs. 42 ± 29 Hounsfield units [HU], p < 0.01), RI (1.14 ± 0.18 vs. 1.08 ± 0.19, p = 0.02), and frequency of adjacent spotty calcium of NCPs (60% vs. 38%, p < 0.01) were significantly different between ACS and non-ACS patients. Frequency of NCPs with minimum CT density <40 HU, RI >1.05, and adjacent spotty calcium was approximately 2-fold higher in the ACS group than in the non-ACS group (43% vs. 22%, p < 0.01). In the ACS group, only RI was significantly different between 21 culprit and 44 nonculprit lesions (1.26 ± 0.16 vs. 1.09 ± 0.17, p < 0.01), and a larger RI (≥1.23) was independently related to the culprit lesions (odds ratio: 12.3; 95% confidential interval: 2.9 to 68.7, p < 0.01), but there was a substantial overlap of the distribution of RI values in these 2 groups of lesions.ConclusionsSixty-four-slice CT angiography demonstrates a higher prevalence of NCPs with vulnerable characteristics in patients with ACS as compared with stable clinical presentation
Feasibility of a whole-body 3 T MRI system for detecting macrophages in mouse carotid atherosclerosis using feco/graphite core-shell nanocrystals
Effect of Heart Rate and Body Mass Index on the Interscan and Interobserver Variability of Coronary Artery Calcium Scoring at Prospective ECG-Triggered 64-Slice CT
FeCo/Graphite Nanocrystals for Multi-Modality Imaging of Experimental Vascular Inflammation
BACKGROUND: FeCo/graphitic-carbon nanocrystals (FeCo/GC) are biocompatible, high-relaxivity, multi-functional nanoparticles. Macrophages represent important cellular imaging targets for assessing vascular inflammation. We evaluated FeCo/GC for vascular macrophage uptake and imaging in vivo using fluorescence and MRI. METHODS AND RESULTS: Hyperlipidemic and diabetic mice underwent carotid ligation to produce a macrophage-rich vascular lesion. In situ and ex vivo fluorescence imaging were performed at 48 hours after intravenous injection of FeCo/GC conjugated to Cy5.5 (n = 8, 8 nmol of Cy5.5/mouse). Significant fluorescence signal from FeCo/GC-Cy5.5 was present in the ligated left carotid arteries, but not in the control (non-ligated) right carotid arteries or sham-operated carotid arteries (p = 0.03 for ligated vs. non-ligated). Serial in vivo 3T MRI was performed at 48 and 72 hours after intravenous FeCo/GC (n = 6, 270 µg Fe/mouse). Significant T2* signal loss from FeCo/GC was seen in ligated left carotid arteries, not in non-ligated controls (p = 0.03). Immunofluorescence staining showed colocalization of FeCo/GC and macrophages in ligated carotid arteries. CONCLUSIONS: FeCo/GC accumulates in vascular macrophages in vivo, allowing fluorescence and MR imaging. This multi-functional high-relaxivity nanoparticle platform provides a promising approach for cellular imaging of vascular inflammation
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