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Troschel, Fabian M., Ravi V. Gottumukkala, Daniel DiCorpo, Julia Mario, Harald C. Ott, Cameron D. Wright, Ashok Muniappan et al. „Feasibility of Perioperative Micro–Computed Tomography of Human Lung Cancer Specimens: A Pilot Study“. Archives of Pathology & Laboratory Medicine 143, Nr. 3 (20.11.2018): 319–25. http://dx.doi.org/10.5858/arpa.2018-0249-oa.
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Context.— Lesion localization during intraoperative frozen section of lung resection specimens can be challenging. Imaging could aid lesion localization while enabling 3-dimensional specimen analysis. Objective.— To assess the feasibility of integrating micro–computed tomography (micro-CT) into the perioperative evaluation of fresh surgical lung resection specimens. Design.— Fresh lung specimens from patients with a presumptive diagnosis of lung cancer were imaged with micro-CT prior to routine histopathologic and molecular analysis. Micro-CT images were assessed to determine image quality, lesion size, and distance from lesion to the nearest surgical margin. Micro-CT measurements were compared to pathologic measurements using Bland-Altman analysis. Results.— A total of 22 specimens from 21 patients were analyzed (mean image acquisition time, 13 ± 6 minutes). Histologic quality of imaged specimens was indistinguishable from a control group of nonimaged lung specimens. Artifacts, most commonly from specimen deflation (n = 8), obscured fine detail on micro-CT images of 10 specimens. Micro-CT could successfully localize the target lesion in the other 12 specimens. Distance to the nearest surgical margin was determined in 10 specimens. Agreement of micro-CT with final pathology was good, with a mean difference of −2.8% (limits of agreement −14.5% to 20.0%) for lesion size and −0.5 mm (limits of agreement −4.4 to 3.4 mm) for distance to nearest surgical margin. Conclusions.— Micro-CT of fresh surgical lung specimens is feasible and has the potential to evaluate the size and location of lesions within resection specimens, as well as distance to the nearest surgical margin, all without compromising specimen integrity.
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Badman, Steven G., Sara F. E. Bell, Judith A. Dean, Jime Lemoire, Luke Coffey, Joseph Debattista, Andrew M. Redmond, Owain D. Williams, Charles F. Gilks und David M. Whiley. „Reduced sensitivity from pooled urine, pharyngeal and rectal specimens when using a molecular assay for the detection of chlamydia and gonorrhoea near the point of care“. Sexual Health 17, Nr. 1 (2020): 15. http://dx.doi.org/10.1071/sh19028.
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Background The aim of this study was to compare the performance of pooled self-collected urogenital, pharyngeal and anorectal specimens to that of individual specimen results for the molecular detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) near the point of care (POC) for diagnostic sensitivity. Methods: Clients (mostly men who have sex with men) attending an urban community testing service and three sex-on-premises venues in Brisbane, Australia, were offered CT and NG testing by trained lay providers. Participants provided three self-collected specimens (urine, pharyngeal and rectal) for testing by GeneXpert (Cepheid, Sunnyvale, CA, USA). If any of the individual specimens from a participant were positive, all three specimens were pooled and retested. Results: Of the 388 participants who provided three individual anatomical specimens, 76 (19.6%) were found to be positive for CT and/or NG at one or more sites. The pooling approach failed to detect five CT rectal and four NG pharyngeal infections. The overall performance (sensitivity) of the pooling approach compared with individual specimen testing and Cohen’s κ were 90.0% and 0.86 respectively for CT and 89.7% and 0.89 respectively for NG. Conclusions: Reduced sensitivity was observed when using pooled specimens for the detection of CT and NG using GeneXpert near the POC, similar to results reported in laboratory-based CT and NG pooling studies. These data suggest specimen pooling is feasible near to the POC, potentially saving time and costs when screening at-risk populations for CT and NG. Our data also suggest a reduction in pooled urine could improve overall test sensitivity.
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SARTORI, MICHEL, MARTIN KUBIAK und PETER MICHALIK. „Deciphering genital anatomy of rare, delicate and precious specimens: first study of two type specimens of mayflies using micro-computed X-ray tomography (Ephemeroptera; Heptageniidae)“. Zoosymposia 11 (18.11.2016): 28–32. http://dx.doi.org/10.11646/zoosymposia.11.1.7.
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The use of non-invasive techniques to study a wide array of zoological specimens has been increasing considerably during the 21st century. Among these techniques, micro-computed X-ray tomography (μ-CT) is gaining much attention. This method may allow access to hardly visible and internal structures of valuable specimens (e.g. type specimens) through virtual dissections. We studied two type specimens of Ephemeroptera belonging to the family Heptageniidae using μ-CT; the male lectotype of Epeorella borneonia Ulmer, 1939 (pinned specimen) and the male holotype of Rhithrogeniella ornata Ulmer, 1939 (specimen in ethanol). These specimens are the only male adults known in their respective genera; hence a detailed description of their genitalia could reveal important taxonomic and phylogenetic information. We present here the first-ever μ-CT study of mayfly type specimens, and confirm that male genitalia of R. ornata lack titillators, whereas those of E. borneonia possess a pair of titillators which were concealed within the penis lobes.
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Ferrero, Dennis V., Holly N. Meyers, Diane E. Schultz und Stephen A. Willis. „Performance of the Gen-Probe AMPLIFIED Chlamydia Trachomatis Assay in Detecting Chlamydia trachomatis in Endocervical and Urine Specimens from Women and Urethral and Urine Specimens from Men Attending Sexually Transmitted Disease and Family Planning Clinics“. Journal of Clinical Microbiology 36, Nr. 11 (1998): 3230–33. http://dx.doi.org/10.1128/jcm.36.11.3230-3233.1998.
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The Gen-Probe AMPLIFIED Chlamydia Trachomatis Assay (AMP CT) uses transcription-mediated amplification and hybridization protection assay procedures to qualitatively detect Chlamydia trachomatisrRNA in urine, endocervical swab, and urethral specimens. The performance of the AMP CT was compared to that of cell culture for endocervical swab and urine specimens from women and urethral and urine specimens from men. Analysis of specimens with discrepant results was performed by a combination of reculture, direct fluorescent-antibody (DFA) staining of specimen sediment, and amplification which targeted a different chlamydial rRNA. A total of 800 urine samples were tested by the AMP CT (607 from women and 193 from men), and 7.1% were positive for C. trachomatis, with a sensitivity of 91.2% and a specificity of 99.6% upon discrepant analysis. A total of 926 swab specimens were tested by culture and AMP CT (717 endocervical swab specimens and 209 urethral swab specimens from men), and 7.7% were positive for C. trachomatis, with a sensitivity and specificity of 100% upon discrepant analysis. The AMP CT is a sensitive and specific nucleic acid hybridization assay for the detection of C. trachomatis in endocervical swab specimens from women, urethral swab specimens from men, and urine specimens from men and women.
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Cai, Li Xun, Lei Jin und Chen Bao. „On Fracture Mechanics Testing Technique Based on Compliance of Specimens“. Key Engineering Materials 385-387 (Juli 2008): 293–96. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.293.
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Based on compliance testing of a straight-notch compact tensile (SN-CT) or a single edge bending (SEB) specimen, this paper present a formula with increment form to calculate plastic part of J-integral, two formulas for a SN-CT specimen and a SEB specimen to transform crack mouth opening displacement (CMOD) v0 to the crack opening displacement (COD) q along load line, and simplified formulas to estimate crack length a and effective young’s modulus E. Furthermore, the relation between v and q of the SN-CT specimens of 45 steel and SEB specimens of 30Cr steel were investigated. The results show that the formulas to describe the relation between the ratio v/q and the dimensionless crack length a/w of the specimens accord with the testing results better.
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Wang,, Xiang, Xiangyi Liu, and und Glen L. Niebur. „Preparation of On-Axis Cylindrical Trabecular Bone Specimens Using Micro-CT Imaging“. Journal of Biomechanical Engineering 126, Nr. 1 (01.02.2004): 122–25. http://dx.doi.org/10.1115/1.1645866.
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The Orientation of trabecular bone specimens for mechanical testing must be carefully controlled. A method for accurately preparing on-axis cylindrical specimens using high-resolution micro-CT imaging was developed. Sixteen cylindrical specimens were prepared from eight bovine tibiae. High-resolution finite element models were generated from micro-CT images of parallelepipeds and used to determine the principal material coordinate system of each parallelepiped. A cylindrical specimen was then machined with a diamond coring bit. The resulting specimens were scanned again to evaluate the orientation. The average deviation between the principal fabric orientation and the longitudinal axis of the cylindrical specimen was only 4.70±3.11°.
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Muren, C., und C. Ytterbergh. „Computed Tomography of Temporal Bone Specimens“. Acta Radiologica. Diagnosis 27, Nr. 6 (November 1986): 645–51. http://dx.doi.org/10.1177/028418518602700605.
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Ten deep-frozen temporal bone specimens were subjected to computed tomography (CT) in five different projections. The possibility of identifying small structures, such as the ossicles and aqueductal lumina, was assessed. In addition, the semicircular canals were measured. Subsequently corresponding measurements were carried out on plastic casts of these specimens for comparison. A temporal bone specimen is well suited as a test object for evaluating the detectability of small and dense natural structures by CT.
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Qiu, H., C. C. Hsu, E. K. Fishman, R. Tuli, C. L. Wolfgang, B. H. Edil, R. H. Hruban, L. Zheng, D. Laheru und J. M. Herman. „Correlation between pancreatic tumor size as measured on 3D CT scan versus pathologic specimen: Impact on radiation treatment volume.“ Journal of Clinical Oncology 29, Nr. 4_suppl (01.02.2011): 276. http://dx.doi.org/10.1200/jco.2011.29.4_suppl.276.
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276 Background: Definition of the target volume for irradiation of pancreatic cancer (PCA) must balance coverage of micrometastatic disease with toxicity. To determine differences between radiographically defined tumors and true pathologic tumor specimens, we correlated the maximum tumor diameter (TD) of preoperatively imaged tumors with resected tumor specimens. Methods: With IRB approval, a retrospective chart review of patients who underwent resection of PCA between 2006 and 2010 was conducted. 73 patients were identified with preoperative CT imaging and pathologic analysis of tumors. 70 of 73 patients had a preoperative 3D CT performed. The TD as measured by a radiologist (EF) on contrast CT and 3D CT reconstruction was compared with that measured by pathological analysis of the resected specimen. Results: 70 patients underwent resection with preoperative CT imaging; 14.1% of these patients had CT performed >6 weeks prior to surgery. The mean (SD) pathologic maximum TD was 31.3 mm (11.3) with range 3 mm to 60 mm. Whereas TD was underestimated by 1.9 mm (1.7 SE) with CT relative to pathologic analysis, this difference was not statistically significant (paired t-test, p=0.27) with a correlation coefficient of 0.265. 3D CT imaging had a smaller mean difference with a mean 3D CT diameter 0.4 mm (1.76 SE) larger than the pathologic specimen (p=0.82) with correlation coefficient 0.222. However, the max TD on 3D CT imaging was on average 2.3 mm larger than on CT (p=0.016) with correlation coefficient 0.798. Of patients with R0 resections (N=48), CT underestimated path size by 3.1 mm (p=0.020), whereas 3D CT was slightly larger (0.1 mm, p=0.949). For R1 resections (n=22), both CT and 3D CT overestimated size (0.8 mm and 1.1 mm, respectively, p>0.5). Conclusions: PCA TD is generally underestimated on CT imaging, yet better approximated with 3D CT. Improved correlation was seen between CT and pathologic specimens following R0 resection. Alternatively, R1 resection specimens were slightly overestimated by CT/3D CT imaging. As a result, clinical target volumes should be expanded accordingly during radiotherapy planning to properly account for these discrepancies in the gross tumor. No significant financial relationships to disclose.
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al-Najami, Issam, Regina G. H. Beets-Tan, Gunvor Madsen und Gunnar Baatrup. „Dual-Energy CT of Rectal Cancer Specimens“. Diseases of the Colon & Rectum 59, Nr. 7 (Juli 2016): 640–47. http://dx.doi.org/10.1097/dcr.0000000000000601.
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BRANCO, R., F. V. ANTUNES und R. F. MARTINS. „Modelling fatigue crack propagation in CT specimens“. Fatigue & Fracture of Engineering Materials & Structures 31, Nr. 6 (Juni 2008): 452–65. http://dx.doi.org/10.1111/j.1460-2695.2008.01241.x.
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Speers, David John, I.-Ly Joanna Chua, Justin Manuel und Lewis Marshall. „Detection of Neisseria gonorrhoeae and Chlamydia trachomatis from pooled rectal, pharyngeal and urine specimens in men who have sex with men“. Sexually Transmitted Infections 94, Nr. 4 (24.10.2017): 293–97. http://dx.doi.org/10.1136/sextrans-2017-053303.
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ObjectivesScreening of men who have sex with men (MSM) for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) requires sampling from anorectal and pharyngeal sites in addition to urogenital sampling. Due to the cost of testing multiple anatomical sites individually testing of pooled specimens has potential merit. The Cepheid GeneXpert CT/NG assay (GeneXpert), which also has potential for point-of-care nucleic acid testing in the sexual health clinic, has not been assessed for pooled specimen testing.MethodsWe prospectively compared GeneXpert testing of pooled pharyngeal and rectal swabs with urine samples to standard of care testing of individual specimens from 107 participants using the Roche cobas 4800 CT/NG assay (cobas) for CT and NG in high-risk MSM attending an inner city sexual health clinic.ResultsWe found testing of pooled pharyngeal, rectal and urine samples by the GeneXpert to have 100% agreement for NG and 94% overall agreement for CT when compared with individual specimen testing by cobas. For CT testing, 14 cases were detected for both tests, 4for cobas only, 2 for GeneXpert only and 89 participants were negative for both tests.ConclusionsPooled specimen CT and NG testing by the GeneXpert was accurate when compared with single specimen testing and has potential for screening MSM for CT and NG. The role of pooled specimen testing with the GeneXpert as a point-of-care nucleic acid test in MSM requires further investigation.
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Ibeh, Christopher, Matteo Pedrotti, Alessandro Tarantino und Rebecca Lunn. „An X-ray CT study of miniature clay sample preparation techniques“. E3S Web of Conferences 92 (2019): 01004. http://dx.doi.org/10.1051/e3sconf/20199201004.
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The quality and reliability of cohesive soil laboratory test data can be significantlyaffected by sample disturbance during sampling or sample preparation. Sample disturbance may affect key design and modelling parameters such as stiffness, preconsolidation stress, compressibility and undrained shear strength, and ultimately determine particle mobilization and shear plane development. The use of X-ray computed tomography (X-CT) in the study of soil is restricted by the inverse relationship of specimen size and obtainable image resolution. This has led to the testing of miniature specimen sizes which are far less than conventional laboratory sample size in a bid to obtain high resolution images and detailed particle-scale soil properties; however, these miniature soil specimens are more prone to sample disturbance. In this work 2% muscovite was mixed with speswhite kaolin clay as a strain marker for use in X-CT. The clay soil sample was prepared from slurry and either consolidated using an oedometer or a gypsum mould. Specimens obtained from a 7 mm tube sampler were compared to lathe trimmed specimens with a diameter (Ø) of 7 mm. Results from X-CT imaging were used to study the influence of sampler type on specimen disturbance, by analysing the muscovite particle orientation of the obtained 3D images. The results show that; for samples subjected to large consolidation stress (>200kpa) lathe trimmed specimens may be subject to lesser disturbance compared to tube sampled specimens.
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Slávik, O., Pavel Hutař, A. Gosch, Michael Berer, Tomáš Vojtek, F. Arbeiter, Gerald Pinter und Luboš Náhlík. „Fatigue Crack Propagation under Mixed Mode I and III in Polyoxymethelene Homopolymer“. Key Engineering Materials 827 (Dezember 2019): 404–9. http://dx.doi.org/10.4028/www.scientific.net/kem.827.404.
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While mixed-mode loading conditions became hot topic recently, it is still quite unexplored area, even in case of metals. In case of polymers, this is even more complex problem, thanks to their higher sensitivity on higher temperatures connected with friction. Since polymer materials are very popular, this topic is of high interest. One of the best experimental specimens for achieving mixed mode loading conditions is the CRB specimen, as it provides clear mixed-mode I + III conditions under tension + torsion. Furthermore, for lifetime predictions it is necessary to calculate some material constants based on measured crack growth rates. However, these crack growth rates are not as easily and accurately measured on CRB specimens, as on CT specimens. Therefore, the main focus of this study is to observe difference between lifetime predictions based on CT and CRB data and possible application of CT data for CRB specimens.
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Meon, Mohd Suhairil, Hazran Husain, Muhamad Fauzi Othman, Juri B. Saedon und Mohd Izzul Khairi Zailani. „Study on Fatigue Crack Growth of 6065-T4 Aluminium Alloy at Different Stress Ratio“. Applied Mechanics and Materials 393 (September 2013): 435–40. http://dx.doi.org/10.4028/www.scientific.net/amm.393.435.
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Fatigue crack growth (FCG) rates of compact tension (CT) specimens of Aluminium alloy 6065-T4 were investigated at room temperature and constant amplitude loadings. Standard CT specimens with pre-cracked according to ASTM E647-E11 were subjected to mode I loading with three R-ratio (0.1, 0.3, and 0.5). Paris law has been used to model the stress ratio effect. A stereozoom microscope was used to observe the microstructure changes before and after the tests. The results indicated that the higher the stress ratio value (from 0.1 to 0.5), the faster the FCG rates on CT specimen of AA 6065-T4.
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Gama, Antonio Lopes, und Sergio Ricardo Kokay Morikawa. „Monitoring Fatigue Crack Growth in Fracture Mechanics Specimens with Piezoelectric Sensors“. Materials Science Forum 758 (Juni 2013): 83–88. http://dx.doi.org/10.4028/www.scientific.net/msf.758.83.
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This paper presents the results of an experimental study on the application of piezoelectric dynamic strain sensors for monitoring the crack growth in fracture mechanics specimens. The performance of the piezoelectric sensors was assessed through fatigue crack propagation tests in three point bend (TPB) specimens and compact tension (CT) specimens. Piezoelectric sensors of lead zirconate titanate (PZT) were placed close to the crack edge of TPB specimens and piezoelectric polyvinilidene fluoride polymer (PVDF) was bonded to the back face of CT specimens. The piezoelectric sensors detect the crack growth by monitoring changes in the dynamic strain field of the specimen. In its simplest mode, the piezoelectric sensors behave like dynamic strain gages, with the main advantage of having a high sensitivity which allows detection of lower strain levels and lower increase in crack length.
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Thomson, P. R., und R. C. K. Wong. „Specimen nonuniformities in water-pluviated and moist-tamped sands under undrained triaxial compression and extension“. Canadian Geotechnical Journal 45, Nr. 7 (Juli 2008): 939–56. http://dx.doi.org/10.1139/t08-023.
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X-ray computed tomography (CT) methods and specialized triaxial equipment were developed to quantify void ratio distribution within saturated sand specimens reconstituted by water pluviation and moist tamping methods during undrained triaxial compression and extension. The CT measurements were obtained at several points along the stress path of each specimen without significant removal of axial load. It was observed that two reconstitution methods yielded very different void ratio distributions within specimens. Significant void ratio redistribution occurred within each specimen during the undrained shearing tests. The influences of void ratio redistribution on globally observed specimen responses are discussed. The findings of this research investigation provide unique insight into fundamental aspects of saturated sand behaviour during undrained triaxial shearing.
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Chen, Ai Jiu, Qing Zhang, Jing Wang und Zhan Fang Ge. „Study on the CT Real-Time Scanning Tests and Deterioration Evolution Process of Recycled Concrete“. Applied Mechanics and Materials 50-51 (Februar 2011): 1019–23. http://dx.doi.org/10.4028/www.scientific.net/amm.50-51.1019.
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Based on CT imaging theory and self-designed loading device, the CT real-time scanning test on recycled concrete under uniaxial static compression has been accomplished, which can be used to specifically study the whole process about microcrack initiation, perforation, coalescence and macrocrack generation in meso-scale. By real-time CT scanning of cylinder recycled concrete specimen, the propagation process of the internal cracks can be effectively tracked during the whole loading process. By extracting and analyzing the CT numbers of CT images under different loading period, the relational expression between CT numbers and deterioration variable was established, which can better reflect the effect of mixing amount of recycled coarse aggregate on deterioration degree of recycled concrete. The results showed that with the increasing mixing amount of recycled coarse aggregate, the deterioration degree of the specimens increased slightly yet uniaxial compression strength of the specimens decreased slightly.
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Crotchfelt, Kimberly A., Barbara Pare, Charlotte Gaydos und Thomas C. Quinn. „Detection of Chlamydia trachomatis by the Gen-Probe AMPLIFIED Chlamydia Trachomatis Assay (AMP CT) in Urine Specimens from Men and Women and Endocervical Specimens from Women“. Journal of Clinical Microbiology 36, Nr. 2 (1998): 391–94. http://dx.doi.org/10.1128/jcm.36.2.391-394.1998.
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Molecular biology-based amplification methods are significantly more sensitive than other methods for the detection of Chlamydia trachomatis. The performance characteristics of the new Gen-Probe AMPLIFIED Chlamydia Trachomatis Assay (AMP CT) with endocervical and urine specimens were compared to those of culture for patients attending two Baltimore City sexually transmitted disease clinics and a clinic for adolescents. AMP CT uses transcription-mediated amplification (TMA) and hybridization protection assay procedures to qualitatively detect C. trachomatis by targeting a 23S rRNA. Discrepant results between culture-negative and AMP CT-positive specimens were resolved by direct fluorescent-antibody staining of sedimented culture transport medium for elementary bodies and by TMA with 16S rRNA as a target. Following discrepant analysis, for 480 female urine specimens AMP CT had a sensitivity of 93.8% and a specificity of 100%. For 464 male urine specimens, the resolved sensitivity and specificity of AMP CT were 95.6 and 98.7%, respectively. For the 479 endocervical swab specimens the sensitivity of AMP CT was 100% and the specificity was 99.5%. Resolved culture sensitivities of AMP CT for female and male swab specimens were 52.3 and 58.9%, respectively. These results demonstrate that AMP CT is highly sensitive for the detection of C. trachomatis in endocervical specimens and in urine specimens from men and women.
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Zhang, Hong, Hongchun Wang, Ruiping Chai, Hongcan Ma und Alida Marcela. „Application of Enhanced CT and Enhanced MRI Fusion Image in the Treatment of Primary Liver Cancer“. Journal of Medical Imaging and Health Informatics 10, Nr. 8 (01.08.2020): 1926–32. http://dx.doi.org/10.1166/jmihi.2020.3194.
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Objective: To provide a decision-making opinion for the clinical selection of treatment options by comparing the preoperative enhanced CT and enhanced MRI scan images of liver transplantation for primary liver cancer with the tumor diameter measurement of postoperative gross specimens. Methods: Nine patients with primary liver cancer who underwent liver transplantation from January 2017 to January 2018 were enrolled. The patients were not treated with local treatment before surgery. Previous imaging studies showed nodular liver cancer. 64-slice spiral CT plain scan+three-stage enhanced scan, 3.0T superconducting MRI scan conventional plain scan, postoperative gross specimen anatomy, record tumor location, number, maximum diameter, compare different imaging techniques and postoperative gross specimens The coincidence rate of the maximum diameter of the same tumor (according to the standard is the maximum diameter difference between the imaging and the gross specimen of the postoperative specimen ≤5 mm), the difference between the groups, and the correlation between the groups. Results: The maximum diameter of the same tumor was measured. The coincidence rate between CT and postoperative gross specimens was 22%. The difference was statistically significant (P = −0.017), the correlation coefficient was 0.928, and the coincidence rate between MRI and postoperative gross specimen was 44%. The difference was statistically significant (P = −0.010) and the correlation coefficient was 0.979. Conclusion: Image fusion technology with enhanced CT and enhanced MRI has changed the treatment decision of some patients with liver cancer, and it has certain value for optimizing treatment.
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Van Der Pol, Barbara, Thomas C. Quinn, Charlotte A. Gaydos, Kimberly Crotchfelt, Julius Schachter, Jeanne Moncada, D. Jungkind et al. „Multicenter Evaluation of the AMPLICOR and Automated COBAS AMPLICOR CT/NG Tests for Detection ofChlamydia trachomatis“. Journal of Clinical Microbiology 38, Nr. 3 (2000): 1105–12. http://dx.doi.org/10.1128/jcm.38.3.1105-1112.2000.
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The fully automated COBAS AMPLICOR CT/NG and semiautomated AMPLICOR CT/NG tests were evaluated in a multicenter trial for the ability to detect Chlamydia trachomatis infections. Test performance compared to that of culture was evaluated for 2,236 matched endocervical swab and urine specimens obtained from women and for 1,940 matched urethral swab and urine specimens obtained from men. Culture-negative, PCR-positive specimens that tested positive in a direct fluorescent-antibody test or in a confirmatory PCR test for an alternative target sequence were resolved as true positives. The overall prevalences of chlamydia were 2.4% in women and 7.2% in men. The COBAS AMPLICOR and AMPLICOR formats yielded concordant results for 98.1% of the specimens. With the infected patient as the reference standard, the resolved sensitivities of COBAS AMPLICOR were 89.7% for endocervical swab specimens, 89.2% for female urine specimens, 88.6% for male urethral swab specimens, and 90.3% for male urine specimens. When results were analyzed as if only a single test had been performed on a single specimen type, the resolved sensitivity was always higher. The resolved specificities of PCR were 99.4% for endocervical swab specimens, 99.0% for female urine specimens, 98.7% for male urethral swab specimens, and 98.4% for male urine specimens. The internal control revealed that 2.4% of the specimens were inhibitory when initially tested. Nevertheless, valid results were obtained for 98.6% of the specimens because 59.1% of the inhibitory specimens were not inhibitory when a second aliquot was tested. The COBAS AMPLICOR and AMPLICOR CT/NG tests for C. trachomatis exhibited equally high sensitivity and specificity with both urogenital swab and urine specimens and thus are well suited for screening for C. trachomatis infection.
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Gajdoš, Ľubomír, und Martin Šperl. „Fracture Toughness Testing for Improving the Safety of Gas Pipelines“. Applied Mechanics and Materials 821 (Januar 2016): 464–70. http://dx.doi.org/10.4028/www.scientific.net/amm.821.464.
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For standard fracture mechanical tests flat specimens (principally CT or SENB) are required. When investigating fracture mechanical properties of thin – walled pipes this brings about a problem because it is necessary to straighten pipe bands. However, this operation causes internal stresses to be induced not only in the semi-product subjected to straightening but also in finished specimens. A question therefore arises to what extent are then the magnitudes of the fracture toughness determined representative for the actual cylindrical wall. To solve this problem fracture mechanics tests were caried out on flat (straightened) CT specimens as well as on curved CT specimens with the natural curvature. The R – curves as well as the resulting parameters of the fracture toughness, obtained for both types of CT specimens, were compared and it was concluded that the fracture toughness of the pipe material determined on straightened CT specimens was practically the same as that obtained on curved CT specimens.
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Raptopoulos, Vassilios, Janet K. Baum, Mary Hochman, Andrew Karellas, Mary-Jane Houlihan und Carl J. D'Orsi. „High Resolution CT Mammography of Surgical Biopsy Specimens“. Journal of Computer Assisted Tomography 20, Nr. 2 (März 1996): 179–84. http://dx.doi.org/10.1097/00004728-199603000-00003.
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Zhen, Wei, Natalie N. Whitfield, Elizabeth Smith, Christine Shaw, Cristina Ivy, Caylee Douglas, Stephanie Bickford und Gregory J. Berry. „Evaluating the Effect of a Modified Sample Preparation on SARS-CoV-2 Detection in a Cartridge-Based Platform“. Journal of Applied Laboratory Medicine 6, Nr. 5 (24.04.2021): 1213–20. http://dx.doi.org/10.1093/jalm/jfab007.
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Abstract Introduction The ePlex® SARS-CoV-2 emergency use authorization (EUA) test is a cartridge-based assay for the detection of SARS-CoV-2 in nasopharyngeal specimens. Since performance data has been previously published on this platform, the manufacturer has modified the workflow design in order to improve assay performance. Evaluation of the new workflow, which eliminated the sample delivery device (SDD), led to a dramatic improvement of assay performance while saving time and making cartridge loading more convenient. Methods 145 confirmed positive nasopharyngeal swab specimens were used to evaluate the assay analytical sensitivity, accuracy, and overall time-saving for the 2 workflows that is with and without the use of SDD on the ePlex SARS-CoV-2 test. Results Elimination of the SDD step led to a dramatic increase in accuracy and the overall limit of detection when using 145 previously defined and valid SARS-CoV-2 positive specimens with relatively low, medium, and high cycle thresholds (CT). This simple workflow change led to an overall detection from 94/145 (64.8%) to 131/145 (90.3%), with an additional 37 specimens being detected. CT value ranges revealed that 90% of the specimens in the 33 ≤ CT < 35.3 CT range were detected, whereas with the SDD workflow, only 30% of positive specimens were detected in this same range. Hands-on time for each specimen also improved and showed overall time savings. Conclusion The simple workflow modification eliminating the SDD led to an overall improvement in the detection of positive specimens and also simplified workflow and reduced hands-on time.
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Bristow, Claire C., Sheldon R. Morris, Susan J. Little, Sanjay R. Mehta und Jeffrey D. Klausner. „Meta-analysis of the Cepheid Xpert® CT/NG assay for extragenital detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections“. Sexual Health 16, Nr. 4 (2019): 314. http://dx.doi.org/10.1071/sh18079.
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Background Most studies evaluating extragenital testing performance for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) detection by the Xpert® CT/NG show high per cent agreement with comparison assays; however, the precision around positive per cent agreement is low and thus the values that have been reported are not highly informative. Therefore, a systematic review was conducted and data from five studies were combined to better assess positive per cent agreement. Methods: The literature indexed on PubMed.gov was searched. Included studies were those that were an evaluation of the Xpert CT/NG assay with rectal and/or pharyngeal specimen types compared with another nucleic acid amplification test (NAAT), the Aptima transcription mediated amplification assay. A full Bayesian method was used for bivariate fixed-effect meta-analysis of positive and negative per cent agreement and pooled estimates (and 95% confidence intervals (CI)) were presented for each. Results: The pooled positive and negative per cent agreement for detection of CT in rectal specimens was 89.72% (95% CI: 84.97%, 93.64%) and 99.23% (95% CI: 98.74%, 99.60%), and in pharyngeal specimens, they were 89.96% (95% CI: 66.38%, 99.72%) and 99.62% (95% CI: 98.95%, 99.95%) respectively. For NG detection in rectal specimens, the pooled positive and negative per cent agreement was 92.75% (95% CI: 87.91%, 96.46%) and 99.75% (95% CI: 99.46%, 99.93%), and in pharyngeal specimens, they were 92.51% (95% CI: 85.84%, 97.18%) and 98.56% (95% CI: 97.69%, 99.23%) respectively. Conclusions: It was found that the Xpert CT/NG assay performed similarly to the Aptima transcription mediated amplification assay for the detection of CT and NG in extragenital specimens. The Xpert assay has the benefit of providing faster results at the point-of-care, thus reducing the turnaround time for results, potentially enabling same-day treatment.
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Sharma, Kuldeep, Pragya Aggarwala, Deepa Gandhi, Anuniti Mathias, Priyanka Singh, Somya Sharma, Sanjay Singh Negi et al. „Comparative analysis of various clinical specimens in detection of SARS-CoV-2 using rRT-PCR in new and follow up cases of COVID-19 infection: Quest for the best choice“. PLOS ONE 16, Nr. 4 (05.04.2021): e0249408. http://dx.doi.org/10.1371/journal.pone.0249408.
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Background An appropriate specimen is of paramount importance in Real Time reverse transcription-polymerase chain reaction (rRT-PCR) based diagnosis of novel coronavirus (nCoV) disease (COVID-19). Thus, it’s pertinent to evaluate various diversified clinical specimens’ diagnostic utility in both diagnosis and follow-up of COVID-19. Methods A total of 924 initial specimens from 130 COVID-19 symptomatic cases before initiation of treatment and 665 follow up specimens from 15 randomly selected cases comprising of equal number of nasopharyngeal swab (NPS), oropharyngeal swab (OPS), combined NPS and OPS (Combined swab), sputum, plasma, serum and urine were evaluated by rRT-PCR. Results Demographic analysis showed males (86) twice more affected by COVID-19 than females (44) (p = 0.00001). Combined swabs showed a positivity rate of 100% followed by NPS (91.5%), OPS (72.3%), sputum (63%), while nCoV was found undetected in urine, plasma and serum specimens. The lowest cycle threshold (Ct) values of targeted genes E, ORF1b and RdRP are 10.56, 10.14 and 12.26 respectively and their lowest average Ct values were found in combined swab which indicates high viral load in combined swab among all other specimen types. Analysis of 665 follow-up multi-varied specimens also showed combined swab as the last specimen among all specimen types to become negative, after an average 6.6 (range 4–10) days post-treatment, having lowest (15.48) and average (29.96) Ct values of ORF1b respectively indicating posterior nasopharyngeal tract as primary nCoV afflicted site with high viral load. Conclusion The combined swab may be recommended as a more appropriate specimen for both diagnosis and monitoring of COVID-19 treatment by rRT-PCR for assessing virus clearance to help physicians in taking evidence-based decision before discharging patients. Implementing combined swabs globally will definitely help in management and control of the pandemic, as it is the need of the hour.
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Jaske, Carl E., und R. Viswanathan. „Use of Miniature Specimens for Creep-Crack-Growth Testing“. Journal of Engineering Materials and Technology 122, Nr. 3 (16.03.2000): 327–32. http://dx.doi.org/10.1115/1.482814.
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Measuring the condition of high-temperature components after many years of service is an important part of remaining life assessment. Tests of miniature specimens have been utilized for this purpose because they require that only small samples be removed from the components, which minimizes or eliminates the need for costly repairs. Miniature-specimen techniques have been developed and validated for creep-rupture testing but not for creep-crack-growth testing. The objective of this research was to develop and validate a procedure for measuring creep-crack-growth behavior using miniature specimens. Based on a past study of Type 316 stainless steel, the single-edge-notch-tension (SENT) specimen configuration was chosen for the current work. SENT specimens were designed and prepared from both base metal and weldments of 2-1/4Cr-1Mo and 1-1/4Cr-1/2Mo steels. The base metal was ASME SA 387, Grade P22 and Grade P11 plate, respectively. The 2-1/4Cr-1Mo steel weldment was a seam-weld hot reheat steam pipe that had been in service for 106,000 hours, while the 1-1/4Cr-1/2Mo steel weldment was from a pipe that had been weld repaired after 244,200 hours of service. SENT specimens with test sections of 10×5×1.5 mm, 15×7.5×1.5 mm, and 20×10×1.5 mm were evaluated. Tests were conducted under constant weight loading or constant load-line displacement loading. Specimens were heated to 538°C using a standard laboratory furnace. Crack length was measured using the DC electric potential drop method. The test results were analyzed to produce creep-crack-growth rate da/dt as a function of the C* integral and compared with data from tests of half-size (1/2T-CT) and standard full-size (1T-CT) compact-tension specimens. For both base metals, the 1/2T-CT and three sizes of SENT specimens gave results that agreed well with those of 1T-CT specimens. For the 2-1/4Cr-1Mo steel weldments, SENT specimens produced good results. However, SENT specimens of the 1-1/4Cr-1/2Mo steel weldments exhibited cracking blunting and no creep crack growth. The reasons for the differences in behavior are discussed and guidance for application of miniature specimens to creep-crack-growth testing is presented. [S0094-4289(00)01403-1]
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Martin, David H., Cathy Cammarata, Barbara Van Der Pol, Robert B. Jones, Thomas C. Quinn, Charlotte A. Gaydos, Kimberly Crotchfelt et al. „Multicenter Evaluation of AMPLICOR and Automated COBAS AMPLICOR CT/NG Tests for Neisseria gonorrhoeae“. Journal of Clinical Microbiology 38, Nr. 10 (2000): 3544–49. http://dx.doi.org/10.1128/jcm.38.10.3544-3549.2000.
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The fully automated COBAS AMPLICOR CT/NG and semiautomated AMPLICOR CT/NG tests were evaluated in a multicenter trial for their ability to detect Neisseria gonorrhoeae infections. Test performance compared to that of culturing was evaluated for 2,192 matched endocervical swab and urine specimens obtained from women and for 1,981 matched urethral swab and urine specimens obtained from men. Culture-negative, PCR-positive specimens that tested positive in a confirmatory PCR test for an alternative target sequence within theN. gonorrhoeae 16S rRNA gene were considered to be true positives. The overall prevalences of gonorrhea were 6.6% in women and 20.1% in men. The COBAS AMPLICOR and AMPLICOR formats yielded concordant results for 98.8% of the specimens and exhibited virtually identical sensitivities and specificities. The results that follow are for the COBAS AMPLICOR format. With the infected patient as the reference standard, the resolved sensitivities of PCR were 92.4% for endocervical swab specimens and 64.8% for female urine specimens. There were no significant differences in these rates between women with and without symptoms. Among symptomatic men, COBAS AMPLICOR sensitivities were 94.1% for urine and 98.1% for urethral swabs; for asymptomatic men, the results were 42.3 and 73.1%, respectively. In comparison, the sensitivities of culturing were 84.8% for endocervical specimens, 92.7% for symptomatic male urethral specimens, and only 46.2% for urethral specimens obtained from asymptomatic men. When PCR results were analyzed as if only a single test had been performed on a single specimen type, the resolved sensitivity was always higher. The resolved specificities of PCR were 99.5% for endocervical swab specimens, 99.8% for female urine specimens, 98.9% for male urethral swab specimens, and 99.9% for male urine specimens. The internal control revealed that 2.1% of specimens were inhibitory when initially tested. Nevertheless, valid results were obtained for 99.2% of specimens because 60.0% of the inhibitory specimens were not inhibitory when a second aliquot was tested. The COBAS AMPLICOR CT/NG test for N. gonorrhoeae exhibited high sensitivity and specificity with urethral swab and urine specimens from men and endocervical swab specimens from women and thus is well suited for diagnosing and screening for N. gonorrhoeae infection.
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Kwon, Hui Hwan, Soo Park, Jae Min Koo und Chang Sung Seok. „The Compaoparison of Characteristics of Fracture Toughness of Materials for Nuclear Piping by Use of Various Types of Specimens“. Advanced Materials Research 415-417 (Dezember 2011): 2281–87. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.2281.
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Since it is difficult to cut off large specimens from nuclear piping, generally the standard CT specimens of 1T are used to perform fracture toughness tests. However, when compared with the test result obtained from a real pipe, the results from CT specimens are been known to be very conservative. Therefore, the U.S. Nuclear Regulatory Commission recommends the use of specimens whose thickness is greater than or equal to the thickness of a real pipe for estimating the stability of crack resistance[1]. In this study, a series of fracture toughness tests were performed using various types of specimens: the standard CT, non-standard Compact Pipe, and Curved CT. The results of the tests were compared.
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Guthrie, Jennifer L., Allison J. Chen, Dalton R. Budhram, Kirby Cronin, Adriana Peci, Paul Nelson, Gustavo V. Mallo et al. „Characteristics of SARS-CoV-2 testing for rapid diagnosis of COVID-19 during the initial stages of a global pandemic“. PLOS ONE 16, Nr. 7 (09.07.2021): e0253941. http://dx.doi.org/10.1371/journal.pone.0253941.
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Accurate SARS-CoV-2 diagnosis is essential to guide prevention and control of COVID-19. Here we examine SARS-CoV-2 molecular-based test performance characteristics and summarize case-level data related to COVID-19 diagnosis. From January 11 through April 22, 2020, Public Health Ontario conducted SARS-CoV-2 testing of 86,942 specimens collected from 80,354 individuals, primarily using real-time reverse-transcription polymerase chain reaction (rRT-PCR) methods. We analyzed test results across specimen types and for individuals with multiple same-day and multi-day collected specimens. Nasopharyngeal compared to throat swabs had a higher positivity (8.8% vs. 4.8%) and an adjusted estimate 2.9 Ct lower (SE = 0.5, p<0.001). Same-day specimens showed high concordance (98.8%), and the median Ct of multi-day specimens increased over time. Symptomatic cases had rRT-PCR results with an adjusted estimate 3.0 Ct (SE = 0.5, p<0.001) lower than asymptomatic/pre-symptomatic cases. Overall test sensitivity was 84.6%, with a negative predictive value of 95.5%. Molecular testing is the mainstay of SARS-CoV-2 diagnosis and testing protocols will continue to be dynamic and iteratively modified as more is learned about this emerging pathogen.
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Gong, Haijun, Venkata Karthik Nadimpalli, Khalid Rafi, Thomas Starr und Brent Stucker. „Micro-CT Evaluation of Defects in Ti-6Al-4V Parts Fabricated by Metal Additive Manufacturing“. Technologies 7, Nr. 2 (12.06.2019): 44. http://dx.doi.org/10.3390/technologies7020044.
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In this study, micro-computed tomography (CT) is utilized to detect defects of Ti-6Al-4V specimens fabricated by selective laser melting (SLM) and electron beam melting (EBM), which are two popular metal additive manufacturing methods. SLM and EBM specimens were fabricated with random defects at a specific porosity. The capability of micro-CT to evaluate inclusion defects in the SLM and EBM specimens is discussed. The porosity of EBM specimens was analyzed through image processing of CT single slices. An empirical method is also proposed to estimate the porosity of reconstructed models of the CT scan.
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Lauderdale, Tsai-Ling, Lenore Landers, Ian Thorneycroft und Kimberle Chapin. „Comparison of the PACE 2 Assay, Two Amplification Assays, and Clearview EIA for Detection of Chlamydia trachomatis in Female Endocervical and Urine Specimens“. Journal of Clinical Microbiology 37, Nr. 7 (1999): 2223–29. http://dx.doi.org/10.1128/jcm.37.7.2223-2229.1999.
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Screening for sexually transmitted diseases (STDs) in a greater proportion of sexually active patients has become an accepted protocol by most health care providers. The purpose of this study was to compare the current test methods for detection of Chlamydia trachomatis used at the University of South Alabama, the PACE 2 assay (Gen-Probe) and the Clearview EIA (Wampole Laboratories), with two amplification technologies, the AMP CT (Gen-Probe) and LCx (Abbott) assays. In addition, a number of demographic parameters were ascertained by asking questions at the time of examination as well as for health care provider concerns and preferences. One urine and four endocervical swab specimens were collected in random order from 787 female patients attending one of four obstetrics-gynecology clinics. Eighty-seven percent of patients had no STD-related symptoms. Patients were considered positive for C. trachomatis if three or more assays (swab and/or urine) were positive. Abbott and Gen-Probe confirmed discrepant results by alternate amplified assays. A total of 66 true-positive specimens were detected by use of the combination of endocervical swabs and urine specimens. After discrepant analysis, sensitivities for endocervical swab specimens for the EIA and the PACE 2, LCx, and AMP CT assays were 50, 81, 97, and 100%, respectively. Sensitivities for the LCx and AMP CT assays with urine specimens were 98 and 81%, respectively. The prevalence of C. trachomatiswas 8.4%, as determined by amplification technology. Overall, the amplification technologies were the most sensitive methods with either swab (AMP CT assay) or urine (LCx assay) specimens. The PACE 2 assay offered the advantage of a simpler and less expensive assay with acceptable sensitivity. The clearview CT EIA, while yielding a rapid in-office result, had unacceptably low sensitivity. The wide variation in performance with amplification assays with urine specimens as reported in both this study and the literature obviates the need to clarify optimal parameters for this specimen type.
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Khader, Samer N., Kathie Schlesinger, Josh Grossman, Richard I. Henry, Mark Suhrland und Amy S. Fox. „APTIMA assay on SurePath liquid-based cervical samples compared to endocervical swab samples facilitated by a real time database“. CytoJournal 7 (02.07.2010): 11. http://dx.doi.org/10.4103/1742-6413.65057.
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Background: Liquid-based cytology (LBC) cervical samples are increasingly being used to test for pathogens, including: HPV, Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) using nucleic acid amplification tests. Several reports have shown the accuracy of such testing on ThinPrep (TP) LBC samples. Fewer studies have evaluated SurePath (SP) LBC samples, which utilize a different specimen preservative. This study was undertaken to assess the performance of the Aptima Combo 2 Assay (AC2) for CT and GC on SP versus endocervical swab samples in our laboratory. Materials and Methods: The live pathology database of Montefiore Medical Center was searched for patients with AC2 endocervical swab specimens and SP Paps taken the same day. SP samples from CT-and/or GC-positive endocervical swab patients and randomly selected negative patients were studied. In each case, 1.5 ml of the residual SP vial sample, which was in SP preservative and stored at room temperature, was transferred within seven days of collection to APTIMA specimen transfer tubes without any sample or patient identifiers. Blind testing with the AC2 assay was performed on the Tigris DTS System (Gen-probe, San Diego, CA). Finalized SP results were compared with the previously reported endocervical swab results for the entire group and separately for patients 25 years and younger and patients over 25 years. Results: SP specimens from 300 patients were tested. This included 181 swab CT-positive, 12 swab GC-positive, 7 CT and GC positive and 100 randomly selected swab CT and GC negative patients. Using the endocervical swab results as the patient’s infection status, AC2 assay of the SP samples showed: CT sensitivity 89.3%, CT specificity 100.0%; GC sensitivity and specificity 100.0%. CT sensitivity for patients 25 years or younger was 93.1%, versus 80.7% for patients over 25 years, a statistically significant difference (P = 0.02). Conclusions: Our results show that AC2 assay of 1.5 ml SP samples transferred to APTIMA specimen transfer medium within seven days is sufficiently sensitive and specific to be used to screen for CT and GC. CT sensitivity may be somewhat reduced in samples from patients over 25 years. SP specimens retained in the original SP fixative for longer time intervals also may have decreased sensitivity, due to deterioration of RNA, but this was not assessed in this study. The ability to tap the live pathology database is a valuable tool that can useful to conduct clinical studies without a costly prospective clinical trial.
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Shi, Lang Jing, Xian Li, Zhen Peng, Shi Ji Wang und Fan Wu. „Study on Mechanical Property of Structural Damaged Expansive Soil with CT-Triaxial Shear Test“. Advanced Materials Research 599 (November 2012): 811–14. http://dx.doi.org/10.4028/www.scientific.net/amr.599.811.
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A series of CT-triaxial shear tests were conducted on expancive soil specimens under controlled suction and confining pressure as 50kPa and 100kPa. The derivative and axial stress in each stage and CT images of inner structure of specimens were obtained .The results show that the different damage location and damage degree on expansive soil samples have different effect on soil mechanical property. The deviatoric stress of smaller damage area sample is larger than of bigger damage area specimen when the damage locates at the same place. The deviatoric strain is independent of the damage degree of samples. The CT images show that with the axial strain increasing, the fissures in soil close gradually, the density of soil increases, and the deformation of samples gets larger with the increase of confining pressure.
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Zhang, Jiantong, Jun Yang, Tiejun Liu, Rongxing Cai und Rui Yang. „Study on Void Structure Reconstruction of Asphalt Mixture by X-Ray Computed Tomography and Otsu’s Method“. Advances in Materials Science and Engineering 2020 (31.08.2020): 1–13. http://dx.doi.org/10.1155/2020/4546731.
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The purpose of this paper is to obtain the pore distribution of asphalt mixture accurately by nondestructive technology. Specimens prepared with four gradations of asphalt mixtures were scanned using X-ray computed tomography (CT) which was used to measure air void sizes at different depths within specimens. The air void distributions of obtained CT images were analyzed using ring blocking segmentation combining Otsu’s method, which provided an accurate estimate of air voids in asphalt mixtures. The image processing results showed that air void distribution was not uniform in the specimens; higher air void concentrations were found at the top and bottom of the specimen, and lower, in the rest of the sample depth. The air void sizes of SUP13 and AC13 are mainly distributed between 0.15 to 0.2 mm, while PA13 and SMA13 are 0.4 to 0.65 mm and 0.4 to 0.7 mm, respectively. It is believed that the CT pictures processed by the ring blocking segmentation combining Otsu’s method is feasible and rational to capture the air voids size and content of asphalt mixtures.+
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Vukelic, Goran, und Josip Brnic. „Numerical Prediction of Fracture Behavior for Austenitic and Martensitic Stainless Steels“. International Journal of Applied Mechanics 09, Nr. 04 (16.05.2017): 1750052. http://dx.doi.org/10.1142/s1758825117500521.
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Two types of stainless steels are compared in this paper, austenitic X15CrNiSi25-20 and martensitic X20Cr13, based on their numerically predicted fracture behavior. There are engineering applications where both of the steels can be considered for use and where these materials can be exposed to crack occurrence and growth, so proper distinction between them is desirable. Comparison is made on the basis of [Formula: see text]-integral values that are numerically determined using finite element (FE) stress analysis results. FE analysis is performed on compact tensile (CT) and single-edge notched bend (SENB) type specimens that are usually used in standardized [Formula: see text]-integral experimental procedures. Calculated [Formula: see text]-integral values are plotted versus crack growth lengths for mentioned specimens. Results show somewhat higher values of [Formula: see text]-integral for steel X20Cr13 than X15CrNiSi25-20. Further, when comparing [Formula: see text]-integral values obtained through FE model of CT and SENB specimen, it is noticed that CT specimens give somewhat conservative results. Results obtained by this analysis can be used in predicting fracture toughness assessment during design process.
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Jose, Nevil Martin, J. Chattopadhyay, P. V. Durgaprasad und N. Naveen Kumar. „Master Curve of 20MnMoNi55 Steel From Miniature CT Specimens“. Procedia Structural Integrity 14 (2019): 403–9. http://dx.doi.org/10.1016/j.prostr.2019.05.049.
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Liu, Shao-Lun, und Ji-Zhou Xie. „Improvement of a Cycle J Integral for CT Specimens“. Journal of Engineering for Gas Turbines and Power 108, Nr. 3 (01.07.1986): 521–24. http://dx.doi.org/10.1115/1.3239940.
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The cycle J integral formula for CT specimens has been improved as follows: ΔJ=(2/Bb)(α1•U + α2•ΔP•Δδ) + (2/Bb)Ue−1.2025a/w + 0.6233 for 0.3≤a/w≤0.53; ΔJ=(2/Bb)(α1•U + α2•ΔP•Δδ) + (2/Bb)Ue−0.02 sin[(π/0.23)(a/w−0.53)] for 0.53<a/w<0.95. This formula is applicable to the fatigue crack propagation range of 0.3≤a/w<0.95. In comparison with other formulae of the cycle J integral, the application range of the above expression is enlarged and its accuracy is also increased to a certain extent.
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KIKUCHI, Masanori, Toshinari TAMURA und Nobuyuki SHUTTO. „Three-Dimensional Stable Grack Growth Analysis of CT Specimens.“ Transactions of the Japan Society of Mechanical Engineers Series A 58, Nr. 551 (1992): 1275–80. http://dx.doi.org/10.1299/kikaia.58.1275.
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Higashi, Masahiro, Naoaki Yamada, Satoshi Imakita, Chikao Yutani, Hatsue Ishibashi-Ueda, Koji Iihara und Hiroaki Naito. „CT-pathologic correlation of non-calcified atherosclerotic arterial plaques: a study using carotid endarterectomy specimens“. British Journal of Radiology 93, Nr. 1109 (01.05.2020): 20190901. http://dx.doi.org/10.1259/bjr.20190901.
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Objective: Pathologic features of atherosclerotic plaques on CT are not established. We compared CT values among pathologically confirmed plaque constituents and evaluated their ability to distinguish plaque constituents. Methods: 50 histopathological images of carotid endarterectomy samples from 10 males and 2 females (age 54–74 years, average 65.9 years) were examined. We compared pre-operative CT [pre-contrast (CT-P), early post-contrast phase (CT-E), delayed post-contrast phase (CT-D)] of lipid-rich necrotic core (NC) and fibrous tissue (F) plaque components with pathological images. The ability of features to differentiate plaque components using several discrimination techniques were compared. Results: CT values of NC and F were 36 ± 13, 45 ± 11 (mean ± standard deviation, Hounsfield unit, HU), 41 ± 17, 69 ± 18, and 44 ± 16, 70 ± 13 in CT-P (p < 0.01), CT-E (p < 0.0001), and CT-D (p < 0.0001), respectively. The threshold, sensitivity, and accuracy for distinguishing NC from F were 44 HU, 74%, and 68%; 55 HU, 85%, and 85%; and 63 HU, 92%, and 84% in CTP, CT-E, and CT-D, respectively. CT-P had lower accuracy than CT-E and CT-D (both p < 0.05), but CT-E and CT-D were similar. CT-E and CT-D yielded 90 and 91% sensitivity and accuracy, respectively in linear discrimination analysis. Conclusion: In both pre- and post-contrast CT, CT values were lower in NC than F. Although values overlapped, using two-phase post-contrast CTs improved discrimination ability. Advances in knowledge: Our findings may help to establish computer-aided diagnosis of vulnerable atherosclerotic plaques in future.
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Heidenreich, A., D. A. Pfister, R. Epplen und B. Brehmer. „11c-choline-PET/CT versus transrectal ultrasound-guided prostate biopsy to diagnose locally recurrent prostate cancer following radiation therapy.“ Journal of Clinical Oncology 29, Nr. 7_suppl (01.03.2011): 119. http://dx.doi.org/10.1200/jco.2011.29.7_suppl.119.
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119 Background: Radical salvage prostatectomy (SRP) represents one local secondary treatment option with curative intent in patients failing radiation therapy (RT) for localized prostate cancer (PCA). 11C-PET/CT represents an innovative imaging study to detect systemic spread of prostate cancer. However, there is only limited experience with regard to the sensitivity of C-PET/CT to detect locally recurrent PCA following radiation therapy. The purpose of our study was to analyse the sensitivity of C-PET/CT to diagnose PCA and extra- and intraprostatic extension. Methods: 45 patients with the suspicion of locally recurrent PCA underwent 12-core transrectal ultrasound- guided biopsy of the prostate, C-PET/CT, bonne scan and radical salvage prostatectomy. Findings of the imaging studies were correlated with the pathohistological findings of the prostate biopsy and the radical prostatectomy specimen. All prostatectomy specimens were proceeded according to the Stanford protocol and the number and location of intraprostatic cancer foci > 5mm were correlated with the PE/CT findings. Results: The mean preoperative serum PSA was 7.8 (2–24) ng/ml; the mean biopsy Gleason Score was 5.6 (4–9). Prostate biopsy was positive in 37/45 (82.2%) patients whereas 8/45 (17.8%) had a negative biopsy despite positive PET/CT findings. PET/CT was positive in 45/45 patients. Radical prostatectomy specimens identified locally recurrent PCA in 44/45 (97.8%). One patient turned out to have pT0pN0 disease despite increasing PSA. PET/CT identified 1, 2, and > 2 intraprostatic cancer foci of significant volume in 23 (51.1%), 13 (28.9%) and 9 (20%) patients, respectively. Sensitivity to detect intraprostatic, histologically proven PCA foci is 95.6% which is significantly superior to the biopsy results. There was a high correlation between the PET/CT results and the final histology of the radical prostatectomy specimens. Conclusions: Choline PET/CT is an innovative imaging to identify patients with locally recurrent PCA following radiation therapy. PET/CT is superior to prostate biopsy and we recommend a PET/CT in patients who are candidates for radical salvage prostatectomy. No significant financial relationships to disclose.
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Murakami, Tetsuya, Hiroyuki Toda und Toshiro Kobayashi. „Effects of Temperature and Loading Rate on Fracture Toughness“. Key Engineering Materials 297-300 (November 2005): 2397–402. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.2397.
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It is known that fracture toughness value is affected by test temperature, specimen thickness and loading rate. In the present study, specimen size and test temperature are varied widely with the obtained data then being analyzed using rate parameter. Additionally, the fracture toughness values are obtained using round bar-type specimen with a circular notch. This result is compared with the result of the CT specimens, and the advantage of using the round bar-type specimen with a circular notch to modify specimen size requirement is discussed. Sample material used is HT780 high tensile strength steel. The test specimens were 1T, 2T and 4T-CT that are described in ASTM E399. Notched round bar-type specimen with a diameter of 15mm and notch root radius of 0.25mm is also used. The test temperature is varied from a low temperature to room temperature, and loading rate is varied about the 1T-CT specimen and the notched round bar-type specimen between static and 1000mm/sec. The test temperature and the loading rate dependency of the fracture toughness values were arranged by the rate parameter. The fracture toughness value has decreased with the decrease in test temperature and with the increase in specimen thickness and loading rate. The fracture toughness value obtained from the notched round bar-type specimen indicated a value close to 2T-CT specimen. It is shown that valid fracture toughness value can be obtained with a small test specimen by the notched round bar-type specimen. The test temperature and the loading rate dependency of the fracture toughness values can be successfully arranged by the rate parameter that can express both temperature and strain rate dependencies. Feasibility of using round bar-type specimen to obtain valid fracture toughness values with less specimen mass was demonstrated.
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Richter-Trummer, Valentin, Roberto M. C. Miranda, Carlos Albuquerque und Paulo M. S. T. de Castro. „Fatigue Crack Striation Spacing for Welded and Base Material CT Steel Specimens“. Materials Science Forum 730-732 (November 2012): 793–98. http://dx.doi.org/10.4028/www.scientific.net/msf.730-732.793.
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Scanning electron microscopy (SEM) observation of the fracture surface of CT specimens was carried out at CEMUP in the context of a FEUP R&D programme for the characterization of fatigue crack growth (FCG) of base material and welded steel CT specimens, carried out under constant load range, reported in a companion paper. The inclusion of specimens of welded material in the FCG characterization programme justified the need for relatively large size specimens. The thickness of the specimens (B=32mm) was approximately identical to the thickness of the structural application of interest, since with thinner specimens the possible effects of residual stress fields would be at least partially lost. The CT specimens were designed according to ASTM E647 standard. The FEI QUANTA 400 FEG / EDAX Pegasus X4M available at CEMUP was used for the SEM observations, carried out in the fatigue fracture surfaces of base and welded (HAZ) steel. Both in base material as well as in welded specimens, it was found that there are regions of the fracture surfaces where no striations are observed, mixed with other regions (patches) with striations. Some regions are featureless (ropey appearance). It was not possible to find a preferential orientation of the striation spacing, that might be directly related with the macroscopic direction of crack propagation; on the contrary, the regions presenting striations seem to have a mainly random orientation. This fact contributes to the absence of correlation between the distance between striations (s) measured using SEM, and the macroscopic fatigue crack growth rate da/dN. Only for substantial values of the crack length/specimen width (a/W) ratio a reasonable agreement between s and da/dN is found. The relationship s/(da/dN) presents values that decrease up to approximately one, as a/W increases. For low values of a/W, s is one or two orders of magnitude greater than da/dN. In the specimens analyzed, fatigue crack growth rates below approximately 2 to 3 x10‑7 m/cycle are associated with approximately constant s values. This border is over the transition between regions I and II of the typical sigmoidal log-log plot of the da/dN vs. DK (I corresponding to the near threshold regime and II to the Paris law regime), and this fact should be accounted for in failure analysis involving SEM of fracture surfaces. Finally, the distance between striations s proved to be insensitive to the presence of important residual stresses in the case of the welded specimens.
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Abdalhamid, Baha, Christopher R. Bilder, Emily L. McCutchen, Steven H. Hinrichs, Scott A. Koepsell und Peter C. Iwen. „Assessment of Specimen Pooling to Conserve SARS CoV-2 Testing Resources“. American Journal of Clinical Pathology 153, Nr. 6 (18.04.2020): 715–18. http://dx.doi.org/10.1093/ajcp/aqaa064.
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Abstract Objectives To establish the optimal parameters for group testing of pooled specimens for the detection of SARS-CoV-2. Methods The most efficient pool size was determined to be five specimens using a web-based application. From this analysis, 25 experimental pools were created using 50 µL from one SARS-CoV-2 positive nasopharyngeal specimen mixed with 4 negative patient specimens (50 µL each) for a total volume of 250 µL. Viral RNA was subsequently extracted from each pool and tested using the CDC SARS-CoV-2 RT-PCR assay. Positive pools were consequently split into individual specimens and tested by extraction and PCR. This method was also tested on an unselected group of 60 nasopharyngeal specimens grouped into 12 pools. Results All 25 pools were positive with cycle threshold (Ct) values within 0 and 5.03 Ct of the original individual specimens. The analysis of 60 specimens determined that 2 pools were positive followed by identification of 2 individual specimens among the 60 tested. This testing was accomplished while using 22 extractions/PCR tests, a savings of 38 reactions. Conclusions When the incidence rate of SARS-CoV-2 infection is 10% or less, group testing will result in the saving of reagents and personnel time with an overall increase in testing capability of at least 69%.
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Roos, E. „A Simple Specimen for the Determination of Elastic-Plastic Fracture Mechanics Parameters on Hollow Cylinders“. Journal of Pressure Vessel Technology 111, Nr. 3 (01.08.1989): 252–58. http://dx.doi.org/10.1115/1.3265672.
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Functions have been derived for a linear-elastic fracture mechanics specimen of an arc-shape, which because of this shape, can be removed relatively easily from pipes or cylindrical components. These specimens can be used for determining crack resistance curves using the J-integral so that, even for thinner components, it is relatively simple to obtain crack growth laws with crack propagation direction over the wall thickness. The ductile fracture mechanics characteristics determined on arc-shaped specimens corresponds well with the values determined on side-grooved CT-25 specimens.
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Buchan, Blake W., Jessica S. Hoff, Cameron G. Gmehlin, Adriana Perez, Matthew L. Faron, L. Silvia Munoz-Price und Nathan A. Ledeboer. „Distribution of SARS-CoV-2 PCR Cycle Threshold Values Provide Practical Insight Into Overall and Target-Specific Sensitivity Among Symptomatic Patients“. American Journal of Clinical Pathology 154, Nr. 4 (20.07.2020): 479–85. http://dx.doi.org/10.1093/ajcp/aqaa133.
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Abstract Objectives We examined the distribution of reverse transcription polymerase chain reaction (RT-PCR) cycle threshold (CT) values obtained from symptomatic patients being evaluated for coronavirus disease 2019 (COVID-19) to determine the proportion of specimens containing a viral load near the assay limit of detection (LoD) to gain practical insight to the risk of false-negative results. We also examined the relationship between CT value and patient age to determine any age-dependent difference in viral load or test sensitivity. Methods We collected CT values obtained from the cobas severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) assay corresponding to 1,213 combined nasopharyngeal-oropharyngeal specimens obtained from symptomatic individuals that were reported as positive or presumptive positive for SARS-CoV-2. CT values were stratified by SARS-CoV target and patient age group. Results In total, 93.3% to 98.4% of specimens demonstrated CT values greater than 3× the assay LoD, at which point false-negative results would not be expected. The mean of CT values between age groups was statistically equivalent with the exception of patients in age group 80 to 89 years, which demonstrated slightly lower CTs. Conclusions Based on the distribution of observed CT values, including the small proportion of specimens with values near the assay LoD, there is a low risk of false-negative RT-PCR results in combined nasopharyngeal-oropharyngeal specimens obtained from symptomatic individuals.
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Lin, Pai-Chen, Jun-Chang Fang, Jia-Wei Lin, Xuan Van Tran und Yern-Chee Ching. „Preheated (Heat-Assisted) Clinching Process for Al/CFRP Cross-Tension Specimens“. Materials 13, Nr. 18 (19.09.2020): 4170. http://dx.doi.org/10.3390/ma13184170.
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Effects of processing parameters on preheated (heat-assisted) clinching process to join aluminum alloy 5052-H32 (AA5052) and thermoplastic carbon-fiber-reinforced-plastic (TP-CFRP) sheets for cross-tension (CT) specimens were first studied. Preheating was critical since brittle TP-CFRP could be softened to avoid fracturing or cracking during clinching process. Four processing parameters, including punching force, die depth, heating mode, and heating temperature, were considered. Quasi-static tests and microscope observations were taken to evaluate AA5052/TP-CFRP clinch joints in CT specimens and determine appropriate processing parameters for fatigue tests. Finally, fatigue data and failure mode of clinch joints in CT specimens were obtained and discussed.
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Dawood, Y., G. J. Strijkers, J. Limpens, R. J. Oostra und B. S. de Bakker. „Novel imaging techniques to study postmortem human fetal anatomy: a systematic review on microfocus-CT and ultra-high-field MRI“. European Radiology 30, Nr. 4 (13.12.2019): 2280–92. http://dx.doi.org/10.1007/s00330-019-06543-8.
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Abstract Background MRI and CT have been extensively used to study fetal anatomy for research and diagnostic purposes, enabling minimally invasive autopsy and giving insight in human fetal development. Novel (contrast-enhanced) microfocus CT (micro-CT) and ultra-high-field (≥ 7.0 T) MRI (UHF-MRI) techniques now enable micron-level resolution that combats the disadvantages of low-field MRI and conventional CT. Thereby, they might be suitable to study fetal anatomy in high detail and, in time, contribute to the postmortem diagnosis of fetal conditions. Objectives (1) To systematically examine the usability of micro-CT and UHF-MRI to study postmortem human fetal anatomy, and (2) to analyze factors that govern success at each step of the specimen preparation and imaging. Method MEDLINE and EMBASE were systematically searched to identify publications on fetal imaging by micro-CT or UHF-MRI. Scanning protocols were summarized and best practices concerning specimen preparation and imaging were enumerated. Results Thirty-two publications reporting on micro-CT and UHF-MRI were included. The majority of the publications focused on imaging organs separately and seven publications focused on whole body imaging, demonstrating the possibility of visualization of small anatomical structures with a resolution well below 100 μm. When imaging soft tissues by micro-CT, the fetus should be stained by immersion in Lugol’s staining solution. Conclusion Micro-CT and UHF-MRI are both excellent imaging techniques to provide detailed images of gross anatomy of human fetuses. The present study offers an overview of the current best practices when using micro-CT and/or UHF-MRI to study fetal anatomy for clinical and research purposes. Key Points • Micro-CT and UHF-MRI can both be used to study postmortem human fetal anatomy for clinical and research purposes. • Micro-CT enables high-resolution imaging of fetal specimens in relatively short scanning time. However, tissue staining using a contrast solution is necessary to enable soft-tissue visualization. • UHF-MRI enables high-resolution imaging of fetal specimens, without the necessity of prior staining, but with the drawback of long scanning time.
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Tu, Jinsong, Ming Zhou, Yuanzhen Liu und Y. Frank Chen. „Bond Behavior of Reinforcing Steel Bars in Thermal Insulation Concrete Exposed to Freeze-Thaw Cycles“. Advances in Materials Science and Engineering 2019 (14.03.2019): 1–12. http://dx.doi.org/10.1155/2019/7374964.
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An experimental study on the bond behavior of reinforcing steel bars in thermal insulation concrete (TIC) mixed with glazed hollow beads (GHBs) and exposed to freeze-thaw (F-T) cycles was carried out. In order to investigate the effects of GHBs on freezing and thawing, the experimental results were compared with those of normal concrete (NC). The comparison shows that, after 300 F-T cycles, both bond behavior and mechanical properties of the TIC specimens are better than those of the NC specimens. Furthermore, in order to investigate the mechanism of frost effect on TIC, the CT scanning method was used to investigate the evolution of the inner structure of a TIC specimen exposed to F-T cycles. The CT images show that the deterioration of bond performance and mechanical properties of the TIC specimen appears to be caused by the increase of micropores in the TIC.
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M.S., Raviraj, Sharanaprabhu C.M. und Mohankumar G.C. „Effect of specimen crack lengths on stress intensity factor for Al6061-TiC composites using experimental and 3D numerical methods“. International Journal of Structural Integrity 8, Nr. 5 (02.10.2017): 506–15. http://dx.doi.org/10.1108/ijsi-09-2016-0030.
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Purpose The purpose of this paper is to present the determination of critical stress intensity factor (KC) both by experimental method and three-dimensional (3D) finite element simulations. Design/methodology/approach CT specimens of different compositions of Al6061-TiC composites (3wt%, 5wt% and 7wt% TiC) with variable crack length to width (a/W=0.3-0.6) ratios are machined from as-cast composite block. After fatigue pre-cracking the specimens to a required crack length, experimental load vs crack mouth opening displacement data are plotted to calculate the KC value. Elastic 3D finite element simulations have been conducted for CT specimens of various compositions and a/W ratios to compute KC. The experimental results indicate that the magnitude of KC depends on a/W ratios, and significantly decreases with increase in a/W ratios of the specimen. Findings From 3D finite element simulation, the KC results at the centre of CT specimens for various Al6061-TiC composites and a/W ratios show satisfactory agreement with experimental results compared to the surface. Originality/value The research work contained in this manuscript was conducted during 2015-2016. It is original work except where due reference is made. The authors confirm that the research in their work is original, and that all the data given in the article are real and authentic. If necessary, the paper can be recalled, and errors corrected.
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Reichler, Mary R., Dana Bruden, Harold Thomas, Bobbie Rae Erickson, Barbara Knust, Nadia Duffy, John Klena et al. „Ebola Patient Virus Cycle Threshold and Risk of Household Transmission of Ebola Virus“. Journal of Infectious Diseases 221, Nr. 5 (19.12.2019): 707–14. http://dx.doi.org/10.1093/infdis/jiz511.
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Abstract Background Identifying risk factors for household transmission of Ebola virus (EBOV) is important to guide preventive measures during Ebola outbreaks. Methods We enrolled all confirmed persons with EBOV disease who were the first case patient in a household from December 2014 to April 2015 in Freetown, Sierra Leone, and their household contacts. Index patients and contacts were interviewed, and contacts were followed up for 21 days to identify secondary cases. Epidemiologic data were linked to EBOV real-time reverse-transcription polymerase chain reaction cycle threshold (Ct) data from initial diagnostic specimens obtained from enrolled index case patients. Results Ct data were available for 106 (71%) of 150 enrolled index patients. Of the Ct results, 85 (80%) were from blood specimens from live patients and 21 (20%) from oral swab specimens from deceased patients. The median Ct values for blood and swab specimens were 21.0 and 24.0, respectively (P = .007). In multivariable analysis, a Ct value from blood specimens in the lowest quintile was an independent predictor of both increased risk of household transmission (P = .009) and higher secondary attack rate among household contacts (P = .03), after adjustment for epidemiologic factors. Conclusions Our findings suggest the potential to use Ct values from acute EBOV diagnostic specimens for index patients as an early predictor of high-risk households and high-risk groups of contacts to help prioritize EBOV disease investigation and control efforts.