54 research outputs found
Degradation of the first frequency of an RC frame with damage levels
Damage in RC structures causes the degradation of stiffness and frequency. In this study, the relationship between the two coefficients and damage severities is numerically investigated considering a three-dimensional (3D) RC frame in which the concrete damage plasticity model (CDPM) and the elastoplastic model are selected for concrete and reinforcements, respectively. Crack propagation is obtained utilizing a nonlinear static pushover analysis (NSPA). After pushing, according to the base shear force versus top displacement curve, the bending stiffness of the structure is determined rapidly based on the first derivative of the relationship. Thereafter, the degradation of the first frequency is obtained based on the derivative of the nonlinear curve of stiffness, the second derivative of the force- displacement curve viz. As a result, it is observed that the degradation of the first frequency of the RC frame is proportional to the severity of damage but not linearly. More significant damage, a more profound decrease in the frequency. Particularly, the frequency of the frame reduces gradually until the base shear force reaches 70% of the ultimate value at which the parameter is 60% of the healthy counterpart. After that, the reduction gets more significant when the bending capacity approaches the ultimate value
Thrombospondin-1 and VEGF in inflammatory bowel disease
Background and aim: Angiogenesis is an important process in the pathogenesis of chronic inflammation. We aimed to study the angiogeneic balance in inflammatory bowel disease (IBD) by evaluating the expression of vascular endothelial growth factor (VEGF) and thrombospondin-1 (TSP-1) on colonic epithelial cells, together with the expression of inducible nitric oxide synthase (iNOS). Methods: Twenty-one ulcerative colitis (UC), 14 Crohn’s disease (CD), 11 colorectal cancer patients, and 11 healthy controls colonic biopsy samples were evaluated immunohistochemically. Results: The expressions of TSP-1, VEGF, and iNOS in UC and CD groups were higher than expression in healthy control group, all with statistical significance. However, in colorectal cancer group, VEGF and iNOS expressions were increased importantly, but TSP-1 expression was not statistically different from healthy control group’s expression. Both TSP-1 and VEGF expressions were correlated with iNOS expression distinctly but did not correlate with each other. Conclusions: Both pro-angiogeneic VEGF and antiangiogeneic TSP-1 expressions were found increased in our IBD groups, but in colorectal cancer group, only VEGF expression was increased. TSP-1 increases in IBD patients as a response to inflammatory condition, but this increase was not enough to suppress pathologic angiogenesis and inflammation in IBD.Keywords: inflammatory bowel disease; thrombospondin-1; VEGF; iNOS; colon cance
Structural health monitoring (SHM) and Nondestructive testing (NDT) of slender masonry structures: A practical review
[EN] The scientific community is hardly working to propose reliable methodologies of analysis and non-invasive technologies of investigation to assess the current state of conservation of historic buildings to verify their ability to resist future threats. These structures, mostly made of masonry, are difficult to assess due to the heterogeneity of materials and their mechanical behavior, but it is vital to preserve this invaluable cultural heritage by suitable structural assessment techniques. A great deal of research atten-tion has been paid to monitoring their structural health; in many recent publications new advanced tech-nological methods have been provided such as cheaper sensors, wireless connections, non-contact surveys and continuous monitoring. A bibliometric study has shown that more than half of the papers on Structural Health Monitoring (SHM) and Nondestructive Testing (NDT) on masonry have been pub-lished between 2018 and 2020, and 30% of those published in 2020 were on 'slender' elements like tow-ers, chimneys or minarets. This paper presents a wide-ranging review of static and dynamic studies published on SHM and NDT of slender masonry structures summarizing and discussing the different experimental techniques used. With respect to the dynamic testing, Operational Modal Analysis (OMA) by accelerometers is the mostly frequent used technique by scholars, but other promising methods such as radar interferometry are also reported. This overall discussion is concluded with a short review of some examples on numerical structural health assessment and signal processing tools. An inclusive list of papers is provided describing the most important slender masonry structures characteristics, natural frequencies, experimental and numerical techniques employed and reference values. This paper, set on a practical perspective, is expected to be of interest to those researchers and practitioners who require an extensive and up-to-date review of this topic.Pallarés Rubio, FJ.; Betti, M.; Bartoli, G.; Pallarés Rubio, L. (2021). Structural health monitoring (SHM) and Nondestructive testing (NDT) of
slender masonry structures: A practical review. Construction and Building Materials. 297:1-33. https://doi.org/10.1016/j.conbuildmat.2021.123768S13329
Seismic Performance of RC Elevated Water Tanks with Frame Staging and Exhibition Damage Pattern
Soft tissue augmentation with autologous fat graft: The dissected pouch technique
Background: Soft tissue augmentation with autologous fat graft has been increasingly used by plastic surgeons despite unpredictable results. Several techniques have been described to prevent the main setback of this technique, fat graft resorption. However, there is no ideal technique described for this purpose. Materials and Methods: Twenty patients with subcutaneous tissue loss, atrophy or hypoplasia were treated with lipofilling. A subcutaneous pouch is dissected at the deformed area and later it is filled with autologous fat graft. Results: Graft maintenance during the postoperative period was satisfactory. Overcorrection was not performed except for the first three cases. Patient, surgeon and layman satisfaction was surveyed. Satisfaction was rated between 0 and 10. The mean score was 7.67 ± 1.22. Conclusion: The authors describe a technique for soft tissue augmentation which effectively corrects contour deformities, provides a low resorption rate and a relatively non-visible scar without causing irregularities
Seismic behaviour of cylindrical elevated tanks with a frame supporting system on various subsoil
133-145The seismic responses of an elevated tank with a frame supporting system on various subsoils are investigated. The finite element method is used for the modelling of the elevated tank and subsoil system. Fixed-base and elastic media assumptions are made for subsoil. The tank fluid has been modelled as lumped masses such as impulsive and convective masses proposed by Housner. An added mass approach is used for fluid-structure interaction by representing both the impulsive mass and the convective mass. For estimating the seismic response of elevated tanks, response spectrum analysis with mode superposition is used. The results obtained from modelling the elevated tanks on a fixed base and on an elastic medium are compared. It has been observed that the seismic response of the elevated tank is altered significantly depending on the properties of the subsoil. The soil-structure interaction especially affects the impulsive modes and lateral displacement of elevated tanks rather than the torsional modes. It is proposed that the coupling effect for perpendicular directions in the axisymmetrical plan geometry should be considered in the seismic design of the elevated tanks
Adenoid cystic carcinoma of the parotid gland: Anastamosis of the facial nerve with the great auricular nerve after radical parotidectomy
Adenoid cystic carcinoma of the parotid gland is a rare and slowly growing, but highly malignant tumor. Surgical resection of a malignant parotid tumor should include resection of the facial nerve when the nerve is involved in the tumor. Facial nerve reconstruction is required after nerve resection. A 14 year-old female presented with complaints of painless enlargement of the right parotid gland and facial asymmetry. Physical examination revealed a firm mass in the region of the parotid gland as well as right facial paralysis. Biopsy obtained from the mass showed an adenoid cystic carcinoma of the parotid gland. A radical parotidectomy with a modified radical neck dissection was carried out. Grafting material for the facial reconstruction was harvested from the great auricular nerve. The proximal main trunk and each distal branch of the facial nerve were coapted with the greater auricular nerve. The patient received radiotherapy after surgery and was seen to achieve grade IV facial function one year after surgery. Thus, the great auricular nerve is appropriate grafting material for coaptation of each distal branch of the facial nerve
Adenoid cystic carcinoma of the parotid gland: Anastamosis of the facial nerve with the great auricular nerve after radical parotidectomy
Adenoid cystic carcinoma of the parotid gland is a rare and slowly growing, but highly malignant tumor. Surgical resection of a malignant parotid tumor should include resection of the facial nerve when the nerve is involved in the tumor. Facial nerve reconstruction is required after nerve resection. A 14 year-old female presented with complaints of painless enlargement of the right parotid gland and facial asymmetry. Physical examination revealed a firm mass in the region of the parotid gland as well as right facial paralysis. Biopsy obtained from the mass showed an adenoid cystic carcinoma of the parotid gland. A radical parotidectomy with a modified radical neck dissection was carried out. Grafting material for the facial reconstruction was harvested from the great auricular nerve. The proximal main trunk and each distal branch of the facial nerve were coapted with the greater auricular nerve. The patient received radiotherapy after surgery and was seen to achieve grade IV facial function one year after surgery. Thus, the great auricular nerve is appropriate grafting material for coaptation of each distal branch of the facial nerve
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