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Sample records for flexure necrosis due

  1. Gastric Necrosis due to Acute Massive Gastric Dilatation

    Directory of Open Access Journals (Sweden)

    Ibrahim Aydin

    2013-01-01

    Full Text Available Gastric necrosis due to acute massive gastric dilatation is relatively rare. Vascular reasons, herniation, volvulus, acute gastric dilatation, anorexia, and bulimia nervosa play a role in the etiology of the disease. Early diagnosis and treatment are highly important as the associated morbidity and mortality rates are high. In this case report, we present a case of gastric necrosis due to acute gastric dilatation accompanied with the relevant literature.

  2. Gastric Necrosis due to Acute Massive Gastric Dilatation.

    Science.gov (United States)

    Aydin, Ibrahim; Pergel, Ahmet; Yucel, Ahmet Fikret; Sahin, Dursun Ali; Ozer, Ender

    2013-01-01

    Gastric necrosis due to acute massive gastric dilatation is relatively rare. Vascular reasons, herniation, volvulus, acute gastric dilatation, anorexia, and bulimia nervosa play a role in the etiology of the disease. Early diagnosis and treatment are highly important as the associated morbidity and mortality rates are high. In this case report, we present a case of gastric necrosis due to acute gastric dilatation accompanied with the relevant literature.

  3. Intestinal Necrosis due to Giant Ovarian Cyst: A Case Report

    OpenAIRE

    Duran, Ali; Duran, Fulay Yilmaz; Cengiz, Fevzi; Duran, Ozgur

    2013-01-01

    Intestinal pathologies due to ovarian cyst are observed rarely. Although a limited number of cases in neonatal and adolescent periods have been observed, no adult case has been reported in the literature. Two mechanisms are involved in intestinal complications due to ovarian cysts: torsion due to adhesion or compression of giant ovarian mass with a diameter of 9-10 cm. We report here a terminal ileum necrosis case due to compression by an ovarian cyst with 11 × 10 × 7 cm size in an 81-year-ol...

  4. Intestinal necrosis in young patient due to arterial tumour embolism

    DEFF Research Database (Denmark)

    Dahle, Einar; Gögenur, Ismail; Nørgaard, Peter

    2012-01-01

    A patient in the thirties, currently undergoing chemotherapy for metastatic osteosarcoma diagnosed 3 years earlier, was admitted with in the emergency department with abdominal pain. Laparoscopic surgery revealed severe inflammation and an abscess. 18 cm of small intestine was removed because...... of intestinal necrosis. Histological examination showed several arterial tumour emboli, morphologically similar to the primary sarcoma. The patient died 1 year after successful surgery. Because of the improved survival of patients with osteosarcoma, acute mesenteric ischaemia should be considered in acute...

  5. Colon Necrosis Due to Sodium Polystyrene Sulfonate with and without Sorbitol: An Experimental Study in Rats.

    Science.gov (United States)

    Ayoub, Isabelle; Oh, Man S; Gupta, Raavi; McFarlane, Michael; Babinska, Anna; Salifu, Moro O

    2015-01-01

    Based on a single rat study by Lillemoe et al, the consensus has been formed to implicate sorbitol rather than sodium polystyrene sulfonate (SPS) as the culprit for colon necrosis in humans treated with SPS and sorbitol. We tested the hypothesis that colon necrosis by sorbitol in the experiment was due to the high osmolality and volume of sorbitol rather than its chemical nature. 26 rats underwent 5/6 nephrectomy. They were divided into 6 groups and given enema solutions under anesthesia (normal saline, 33% sorbitol, 33% mannitol, SPS in 33% sorbitol, SPS in normal saline, and SPS in distilled water). They were sacrificed after 48 hours of enema administration or earlier if they were very sick. The gross appearance of the colon was visually inspected, and then sliced colon tissues were examined under light microscopy. 1 rat from the sorbitol and 1 from the mannitol group had foci of ischemic colonic changes. The rats receiving SPS enema, in sorbitol, normal saline, distilled water, had crystal deposition with colonic necrosis and mucosal erosion. All the rats not given SPS survived until sacrificed at 48 h whereas 11 of 13 rats that received SPS in sorbitol, normal saline or distilled water died or were clearly dying and sacrificed sooner. There was no difference between sorbitol and mannitol when given without SPS. In a surgical uremic rat model, SPS enema given alone or with sorbitol or mannitol seemed to cause colon necrosis and high mortality rate, whereas 33% sorbitol without SPS did not.

  6. Bilateral avascular necrosis of the femoral head due to the use of heroin: A case report.

    Science.gov (United States)

    Ozkunt, Okan; Sarıyılmaz, Kerim; Sungur, Mustafa; Ilen, Ferhat; Dikici, Fatih

    2015-01-01

    Femoral head avascular necrosis is caused by disruption of the blood supply of the femoral head, which finally results in hip dysfunction. Non traumatic osteonecrosis may related with corticosteroid use, alcohol abuse, SLE, hemoglobinopathies or exposure to cytotoxic agents. But avascular necrosis of the femoral head (ANFH) due to heroin use is a rare condition. We report a patient with bilateral ANFH due to heroin use treated by simultaneous bilateral hip arthroplasty. 37 year-old male patient presented with bilateral hip pain that had been occurring for four years. The patient had no history of smoking, excessive drinking, using corticosteroid and the other drugs or trauma but used heroin for 10 years. In clinic and radiologic examination indicated advanced degenerative changes on both hip due to femoral head avascular necrosis. The patient was treated with simultaneous bilateral total hip arthroplasty. After 6 months postoperatively the active hip range of motion was painless. Avascular femoral head necrosis caused by the using of heroin is rare. Ultimately, osteonecrosis of the femoral head occurs through one final common pathway, which is decreased blood flow to the femoral head that leads bone ischemia and death. But it is still unknown that heroin's systemic effects. Intravenous drug use more as a serious problem for today. There is a need for comprehensive studies to demonstrate effects of heroin on bone and vascularity metabolism. Heroin use will be important problem for population. That's why is crucial to understand the effect of heroin. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  7. Hemorrhagic necrosis due to peliosis hepatis: imaging findings and pathological correlation

    International Nuclear Information System (INIS)

    Vignaux, O.; Legmann, P.; Bonnin, A.; Pinieux, G. de; Chaussade, S.; Couturier, D.; Spaulding, C.

    1999-01-01

    Peliosis hepatis is an uncommon liver condition characterized by blood-filled cavities. We report the CT, angiographic and MR features of a case of peliosis hepatis with no obvious etiology and spontaneously regressing hemorrhagic necrosis. Helical CT showed multiple peripheral low-density regions with foci of spontaneous high density suggesting the presence of blood component. On MR imaging, the multiple peripheral lesions were hypointense on T1-weighted and hyperdense on T2-weighted images, with bright foci on all sequences suggesting subacute blood. Angiography showed no evidence of tumor or vascular malformation; multiple nodular vascular lesions filling in the parenchymal phase and persisting in the venous phase suggested blood-filled cavities. Pathological examination showed blood-filled spaces with no endothelial lining, characteristic of the parenchymal type of peliosis. Knowledge of the imaging features of hemorrhagic necrosis due to peliosis hepatis is important since it can be responsive to antibiotic therapy. Furthermore, differentiating hemorrhagic necrosis from hepatic abscess avoids dangerous and sometimes fatal percutaneous drainage. (orig.)

  8. Skin necrosis in a critically ill patient due to a blood pressure cuff

    Directory of Open Access Journals (Sweden)

    Devbhandari Mohan

    2006-01-01

    Full Text Available The non-invasive method of blood pressure measurement is regarded as a safe procedure and the reports of any serious complications are rare. We report a unique case of extensive skin necrosis due to an intermittently inflating blood pressure cuff in a 65-year-old critically ill lady following a third time redo mitral valve surgery. A brief review of the literature on complications associated with noninvasive method of measurement of blood pressure is presented along with possible mechanisms of skin injury and ways to avoid it.

  9. Experimental study on the cracking behavior of reinforced concrete hollow cylinders subjected to temperature gradient and the assessment of decrease in flexural rigidity due to cracking

    International Nuclear Information System (INIS)

    Aoyagi, Yukio; Onuma, Hiroshi; Okazawa, Takao

    1976-01-01

    Altough the consideration of thermal stress constitutes one of the primary factors governing the design of the hollow cylindrical structures made of reinforced concrete and subjected to temperature gradient, such as radiation-shielding walls and reactor containment vessels, the method of rationally evaluating the safety to such stress has not been established so far. The purposes of this study are to investigate the conditions under which cracks initiate in reinforced concrete structures due to temperature gradient, and to evaluate the decreases in the flexural rigidity after cracking, mainly on the basis of experiment. Three hollow cylinders with top and bottom slabs, 120 cm height and 100 cm outside diameter, were tested. The cylinders were externally cooled by being immersed in water, and internally heated by circulating hot water through the cavities. The maximum temperature difference of 65 deg C was attained. The strain was measured, and the crack patterns were observed. A reinforced concrete beam of 3.8 m length was subjected to temperature difference of 65 deg C. Horizontal cracks appeared first at 27 deg C, and vertical cracks followed at 31 deg C difference at the middle of cylindrical walls. It was assumed that the first cracks appear at the tensile strain of 100 x 10 -6 , and the calculated result was agreed fairly well with the observed temperature difference. The rational method for evaluating the decrease in flexural rigidity due to cracking was proposed by the authors. (Kako, I.)

  10. An Investigation of Energy Transmission Due to Flexural Wave Propagation in Lightweight, Built-Up Structures. Thesis

    Science.gov (United States)

    Mickol, John Douglas; Bernhard, R. J.

    1986-01-01

    A technique to measure flexural structure-borne noise intensity is investigated. Two accelerometers serve as transducers in this cross-spectral technique. The structure-borne sound power is obtained by two different techniques and compared. In the first method, a contour integral of intensity is performed from the values provided by the two-accelerometer intensity technique. In the second method, input power is calculated directly from the output of force and acceleration transducers. A plate and two beams were the subjects of the sound power comparisons. Excitation for the structures was either band-limited white noise or a deterministic signal similar to a swept sine. The two-accelerometer method was found to be sharply limited by near field and transducer spacing limitations. In addition, for the lightweight structures investigated, it was found that the probe inertia can have a significant influence on the power input to the structure. In addition to the experimental investigation of structure-borne sound energy, an extensive study of the point harmonically forced, point-damped beam boundary value problem was performed to gain insight into measurements of this nature. The intensity formulations were also incorporated into the finite element method. Intensity mappings were obtained analytically via finite element modeling of simple structures.

  11. False-positive breast screening due to fat necrosis following mammography

    International Nuclear Information System (INIS)

    Cawson, Jennifer N.; Malara, Frank A.

    2004-01-01

    Traumatic fat necrosis can result in a spectrum of imaging appearances that range from characteristically benign to those indistinguishable from malignancy. In such cases, biopsy might be required for diagnosis. The present case demonstrates a suspicious mammographic mass lesion appearing following a haematoma caused by a previous screening mammogram Copyright (2004) Blackwell Publishing Asia Pty Ltd

  12. Thoracic aortic aneurysm in a child due to cystic medial necrosis

    International Nuclear Information System (INIS)

    Kuribayashi, Sachio; Watabe, Tsuneya; Ohtaki, Makoto; Matsuyama, Shoya; Ogawa, Junichi

    1983-01-01

    The valuable role of computed tomography (CT) was stressed in the diagnosis of thoracic aortic aneurysm in an asymptomatic 12-year-old child. She initially presented mediastinal mass on plain chest film. A saccular thoracic aortic aneurysm was highly suspected from the CT findings, and it was confirmed on angiography. Pathological examination of the aneurysmal wall revealed cystic medial necrosis. (author)

  13. Colonic necrosis due to calcium polystyrene sulfonate (Kalimate not suspended in sorbitol

    Directory of Open Access Journals (Sweden)

    María Dolores Castillo-Cejas

    2013-04-01

    Full Text Available Cation-exchange resins are used in the management of hyperkalemia, particularly in patients with end-stage renal disease. These resins were associated with gastrointestinal tract lesions, especially sodium polystyrene sulfonate (Kayexalate mixed with sorbitol. We present a case of colonic necrosis after the administration of calcium polystyrene sulfonate (Kalimate not suspended in sorbitol.

  14. Skin Necrosis with Oculomotor Nerve Palsy Due to a Hyaluronic Acid Filler Injection

    Directory of Open Access Journals (Sweden)

    Jae Il Lee

    2017-07-01

    Full Text Available Performing rhinoplasty using filler injections, which improve facial wrinkles or soft tissues, is relatively inexpensive. However, intravascular filler injections can cause severe complications, such as skin necrosis and visual loss. We describe a case of blepharoptosis and skin necrosis caused by augmentation rhinoplasty and we discuss the patient’s clinical progress. We describe the case of a 25-year-old female patient who experienced severe pain, blepharoptosis, and decreased visual acuity immediately after receiving a filler injection. Our case suggests that surgeons should be aware of nasal vascularity before performing an operation, and that they should avoid injecting fillers at a high pressure and/or in excessive amounts. Additionally, filler injections should be stopped if the patient complains of severe pain, and appropriate measures should be taken to prevent complications caused by intravascular filler injections.

  15. Bilateral Atraumatic Avascular Necrosis of Both the Humeral and Femoral Heads due to the Corticosteroid Usage

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    Okkes Bilal

    2013-08-01

    Full Text Available Avascular necrosis is frequently associated with femoral head involvement and may also be observed in the knee joint, humeral head, wrist and foot. Avascular necrosis may also affect multiple joints. Bilateral involvement of both humeral and femoral heads is a rare condition in the same patient. A patient who complained about a sustained pain in both of his shoulders and hips for a few years applied to our outpatient clinic. The patient who had oral steroid treatment episodically was diagnosed with ulcerative colitis seven years ago. Arthroscopy-assisted decompression to the shoulder joints and core decompression to both hip joints were applied. The range of motions of both humeral and femoral joints was limited and painful prior to the surgical treatment. A follow-up after five years later showed that the patient's range of motions of joints was normal and no further treatment was necessary. [Arch Clin Exp Surg 2013; 2(4.000: 246-250

  16. Important hypercalcemia due to subcutaneous fat necrosis treated with pamidronate in an infant with severe hypoxic-ischemic encephalopathy

    OpenAIRE

    Pasqua Anna Quitadamo; Antonio Villani; Piero Paolo Cristalli; Marina Marinelli; Anita Riganti; Michele Bisceglia; Alberto Gatta

    2016-01-01

    Subcutaneous fat necrosis (SCFN) of the newborn is an uncommon form of panniculitis that occurs after fetal distress and involves fatty areas during the first weeks of life. This rare disorder is generally self-limiting and undergoes complete regression. However, it can be complicated with a potentially life-threatening hypercalcemia. We report a case of severe hypercalcemia due to SCFN occurring after serious perinatal hypoxic injury, which resolved by intravenous administration of pamidrona...

  17. Important hypercalcemia due to subcutaneous fat necrosis treated with pamidronate in an infant with severe hypoxic-ischemic encephalopathy

    Directory of Open Access Journals (Sweden)

    Pasqua Anna Quitadamo

    2016-08-01

    Full Text Available Subcutaneous fat necrosis (SCFN of the newborn is an uncommon form of panniculitis that occurs after fetal distress and involves fatty areas during the first weeks of life. This rare disorder is generally self-limiting and undergoes complete regression. However, it can be complicated with a potentially life-threatening hypercalcemia. We report a case of severe hypercalcemia due to SCFN occurring after serious perinatal hypoxic injury, which resolved by intravenous administration of pamidronate. This treatment was rapidly effective and well tolerated. We suggest that pamidronate could be the first-line therapy for severe hypercalcemia in SCFN.

  18. Flexural pivot device

    International Nuclear Information System (INIS)

    Flaherty, Robert.

    1986-01-01

    A flexural pivot device or rotational actuator comprises first and sceond tubular members connected by flexural members of shape-memory-alloy. These are curved in the austenitic phase at a first temperature and after cooling to the martensitic phase are flattened. On heating one of the flexural members, it bends causing relative rotation of the tubular members. Heating of another member can produce opposite rotation. Heating is electrical or by hot gas. The device may be used in a nuclear reactor. (author)

  19. Combined cytotoxic effects of tumor necrosis factor-alpha with various cytotoxic agents in tumor cell lines that are drug resistant due to mutated p53

    NARCIS (Netherlands)

    Sleijfer, S; Le, T. K. P.; de Jong, S.; Timmer-Bosscha, H; Withoff, S; Mulder, NH

    Several studies suggest that tumor necrosis factor-alpha (TNF) is able to overcome drug resistance in tumors. Whether TNF is able to do so in tumor cell lines that are drug resistant due to a mutation in the tumor suppressor gene p53 is unclear. Therefore, we studied the in vitro cytotoxic effects

  20. Risk of tuberculosis in patients treated with tumor necrosis factor antagonists due to incomplete prevention of reactivation of latent infection.

    Science.gov (United States)

    Gómez-Reino, Juan J; Carmona, Loreto; Angel Descalzo, Miguel

    2007-06-15

    To evaluate the causes of new cases of active tuberculosis (ATB) in patients treated with tumor necrosis factor (TNF) antagonists included in the national registry BIOBADASER (Base de Datos de Productos Biológicos de la Sociedad Española de Reumatología) after the dissemination of recommendations to prevent reactivation of latent tuberculosis infection (LTBI). Incidence rate of ATB per 100,000 patient-years and 95% confidence intervals (95% CIs) were calculated in patients entering BIOBADASER after March 2002 and were stratified by compliance with recommendations (complete or incomplete). ATB rates in BIOBADASER were compared with the background rate and the rate in the rheumatoid arthritis cohort EMECAR (Estudio de la Morbilidad y Expresión Clínica de la Artritis Reumatoide) not treated with TNF antagonists. In addition, rates of ATB among patients treated with adalimumab, etanercept, and infliximab were estimated and compared only for treatments started after September 2003, when all 3 drugs became fully available. Following March 2002, a total of 5,198 patients treated with a TNF antagonist were registered in BIOBADASER. Fifteen ATB cases were noted (rate 172 per 100,000 patient-years, 95% CI 103-285). Recommendations were fully followed in 2,655 treatments. The probability of developing ATB was 7 times higher when recommendations were not followed (incidence rate ratio 7.09, 95% CI 1.60-64.69). Two-step tuberculosis skin test for LTBI was the major failure in complying with recommendations. New cases of ATB still occur in patients treated with all available TNF antagonists due to lack of compliance with recommendations to prevent reactivation of LTBI. Continuous evaluation of recommendations is required to improve clinical practice.

  1. Avascular Necrosis

    Science.gov (United States)

    ... Financial Reports Watchdog Ratings Feedback Contact Select Page Avascular Necrosis Home > Cancer Resources > Late Effects of Treatment > Avascular Necrosis Avascular necrosis (AVN) is a disorder resulting from ...

  2. Estimating flexural rigidity and load magnitude required for formation of Ross Island flexure moat

    Science.gov (United States)

    Jha, S.; Harry, D. L.; Wenman, C. P.

    2017-12-01

    Lithospheric flexural subsidence around Ross Island in West Antarctica led to formation of the Ross Island flexure moat. This subsidence was caused by two major volcanic phases on Ross Island. The first phase saw the first surficial expression of Ross Island and volcanism at Mt. Bird to the north of Ross Island, which lasted from 5.2 - 2.9 Ma. The second phase lasted from 1.78 Ma to present and is comprised of eruptions from Mt. Terror to the east, Mt. Erebus to the west and Hut Point Peninsula (HPP) to the south of Ross Island. Flexural subsidence of the lithosphere due to volcanism on Ross Island led to formation of a sedimentary moat around the island, which is preserved in stratigraphy imaged on seismic reflection profiles. We identified 5 unconformities (from deepest upward Ri, RMU1, RMU2, RMU3, RMU4) in the seismic surveys which correspond to flexural subsidence episodes around Ross Island since early Pliocene. Ri (4.4 Ma) lies near the bottom of the flexural moat and RMU4 near the seafloor and top of the moat fill. These unconformities were used to make isopach maps to constrain flexure modeling of the area. Isopach maps show circular or semi-circular flexure basins around Ross Island which is approximated using a continuous plate, point load flexure model. We used Ri - sea floor isopach to constrain flexure models for 5 profiles centered on 4 volcanic centers and trending radially out of Ross Island. Flexure models along two profiles beginning on Mt. Bird and one profile off HPP show a flexural rigidity range of 1.47 - 6.44 x 1018 Nm with load center of mass on Mt. Bird and on HPP, respectively. A similar model along a profile initiating on Mt. Terror, passing through Mt Erebus and extending west of Ross Island across the moat, yielded a higher flexural rigidity estimate of 2.03 x 1019 Nm with load centered at Mt. Erebus. A flexure model to the north east of Ross Island along a profile beginning at Mt Terror and trending north, provide the highest flexural

  3. Bivalent Llama Single-Domain Antibody Fragments against Tumor Necrosis Factor Have Picomolar Potencies due to Intramolecular Interactions

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    Els Beirnaert

    2017-07-01

    Full Text Available The activity of tumor necrosis factor (TNF, a cytokine involved in inflammatory pathologies, can be inhibited by antibodies or trap molecules. Herein, llama-derived variable heavy-chain domains of heavy-chain antibody (VHH, also called Nanobodies™ were generated for the engineering of bivalent constructs, which antagonize the binding of TNF to its receptors with picomolar potencies. Three monomeric VHHs (VHH#1, VHH#2, and VHH#3 were characterized in detail and found to bind TNF with sub-nanomolar affinities. The crystal structures of the TNF–VHH complexes demonstrate that VHH#1 and VHH#2 share the same epitope, at the center of the interaction area of TNF with its TNFRs, while VHH#3 binds to a different, but partially overlapping epitope. These structures rationalize our results obtained with bivalent constructs in which two VHHs were coupled via linkers of different lengths. Contrary to conventional antibodies, these bivalent Nanobody™ constructs can bind to a single trimeric TNF, thus binding with avidity and blocking two of the three receptor binding sites in the cytokine. The different mode of binding to antigen and the engineering into bivalent constructs supports the design of highly potent VHH-based therapeutic entities.

  4. Electrical remodeling of cardiac myocytes from mice with heart failure due to the overexpression of tumor necrosis factor-alpha.

    Science.gov (United States)

    Petkova-Kirova, Polina S; Gursoy, Erdal; Mehdi, Haider; McTiernan, Charles F; London, Barry; Salama, Guy

    2006-05-01

    Mice that overexpress the inflammatory cytokine tumor necrosis factor-alpha in the heart (TNF mice) develop heart failure characterized by atrial and ventricular dilatation, decreased ejection fraction, atrial and ventricular arrhythmias, and increased mortality (males > females). Abnormalities in Ca2+ handling, prolonged action potential duration (APD), calcium alternans, and reentrant atrial and ventricular arrhythmias were previously observed with the use of optical mapping of perfused hearts from TNF mice. We therefore tested whether altered voltage-gated outward K+ and/or inward Ca2+ currents contribute to the altered action potential characteristics and the increased vulnerability to arrhythmias. Whole cell voltage-clamp recordings of K+ currents from left ventricular myocytes of TNF mice revealed an approximately 50% decrease in the rapidly activating, rapidly inactivating transient outward K+ current Ito and in the rapidly activating, slowly inactivating delayed rectifier current IK,slow1, an approximately 25% decrease in the rapidly activating, slowly inactivating delayed rectifier current IK,slow2, and no significant change in the steady-state current Iss compared with controls. Peak amplitudes and inactivation kinetics of the L-type Ca2+ current ICa,L were not altered. Western blot analyses revealed a reduction in the proteins underlying Kv4.2, Kv4.3, and Kv1.5. Thus decreased K+ channel expression is largely responsible for the prolonged APD in the TNF mice and may, along with abnormalities in Ca2+ handling, contribute to arrhythmias.

  5. Flexural phonon limited phonon drag thermopower in bilayer graphene

    Science.gov (United States)

    Ansari, Mohd Meenhaz; Ashraf, SSZ

    2018-05-01

    We investigate the phonon drag thermopower from flexural phonons as a function of electron temperature and carrier concentration in the Bloch-Gruneisen regime in non-strained bilayer graphene using Boltzmann transport equation approach. The flexural phonons are expected to be the major source of intrinsic scattering mechanism in unstrained bilayer graphene due to their large density. The flexural phonon modes dispersion relation is quadratic so these low energy flexural phonons abound at room temperature and as a result deform the bilayer graphene sheet in the out of plane direction and affects the transport properties. We also produce analytical result for phonon-drag thermopower from flexural phonons and find that phonon-drag thermopower depicts T2 dependence on temperature and n-1 on carrier concentration.

  6. Haemorrhagic necrosis of the grey matter of the spinal cord due to accidental injection of iopamidol in a patient with multiple neurofibromas; a clinico-pathological study

    International Nuclear Information System (INIS)

    Roos, R.A.C.; Wintzen, A.R.; Voormolen, J.H.C.; Vielvoye, G.J.; Bots, G.T.A.M.

    1988-01-01

    Cervical laminectomy was performed in a 34-year old man with multiple spinal neurofibromas because of a slowly progressive medullary compression. Four weeks later a rapid deterioration necessitated iopamidol myelography by left lateral cervical puncture at C2 level. Despite the establishment of adequate spinal fluid contact, resulting in imaging of the subarachnoid space, part of the contrast medium entered the spinal cord, thus delineating a syrinx from the upper cervical extending to the upper thoracic level. After the puncture the patient developed triplegia, involving the left arm and both legs and a paresis of the right arm. He died from aspiration pneumonia. Autopsy revealed haemorrhagic necrosis of the spinal grey matter. This adverse effect of myelography is argued to have been conditioned by the extreme immobility and displacement of the spinal cord due to the presence of multiple neurofibromas. The deterioration four weeks after the operation was probably caused by a further compression of the spinal cord. (orig.)

  7. Splenic flexure volvulus presenting with gangrene

    International Nuclear Information System (INIS)

    Machado, Norman O; Chopra, Pradeep J; Subramanian, Sureshkannan K

    2009-01-01

    Volvulus of the splenic flexure is very rare cause of colonic obstruction constituting 2% of cases of colonic segmental volvulus. Primary splenic flexure volvulus (SFV) is due to congenital absence or laxity of the phrenocolic, gastro colic, and splenocolic ligaments while secondary volvulus is due to other causes including some prior surgery releasing these ligaments. A preoperative diagnosis can be established based on the characteristic radiological findings on plain x-ray abdomen and CT scan. We present a case of SFV in a young man who presented with acute abdominal pain, and distension, and illustrate the usefulness of CT scan, and plain x-ray of the abdomen in making a preoperative diagnosis. Laparotomy revealed a gangrenous SFV, which was resected and primary anastomosis was carried out. Literature is reviewed with regards to predisposing factors, presentation, investigation, and management among the more than 32 cases reported so far. (author)

  8. Flexural reinforced concrete member with FRP reinforcement

    OpenAIRE

    Putzolu, Mariana

    2017-01-01

    One of the most problematic point in construction is the durability of the concrete especially related to corrosion of the steel reinforcement. Due to this problem the construction sector, introduced the use of Fiber Reinforced Polymer, the main fibers used in construction are Glass, Carbon and Aramid. In this study, the author aim to analyse the flexural behaviour of concrete beams reinforced with FRP. This aim is achieved by the analysis of specimens reinforced with GFRP bars, with theoreti...

  9. Flexural eczema versus atopic dermatitis.

    Science.gov (United States)

    Jacob, Sharon E; Goldenberg, Alina; Nedorost, Susan; Thyssen, Jacob P; Fonacier, Luz; Spiewak, Radoslaw

    2015-01-01

    Flexural eczema and atopic dermatitis are frequently synonymized. As respiratory atopy is rarely tested for and found in these patients, systematically equating a flexural distribution of dermatitis with atopic dermatitis may too frequently result in misclassified diagnoses and potentially missed opportunity for intervention toward improving patients' symptoms and quality of life. We present a critical review of the available evidence for the atopic dermatitis diagnosis and discuss the similarities between atopic dermatitis and allergic contact dermatitis. Because neither flexural predilection nor atopy is specific for atopic dermatitis, we conclude that the term atopic dermatitis is a misnomer and propose an etymologic reclassification of atopic dermatitis to "atopy-related" dermatitis. Allergic contact dermatitis can induce an atopic dermatitis-like phenotype, and thus, flexural dermatitis cannot be assumed as atopic without further testing. Patch testing should at least be considered in cases of chronic or recurrent eczema regardless of the working diagnosis.

  10. Flexural eczema versus atopic dermatitis

    DEFF Research Database (Denmark)

    Jacob, Sharon E; Goldenberg, Alina; Nedorost, Susan

    2015-01-01

    Flexural eczema and atopic dermatitis are frequently synonymized. As respiratory atopy is rarely tested for and found in these patients, systematically equating a flexural distribution of dermatitis with atopic dermatitis may too frequently result in misclassified diagnoses and potentially missed...... opportunity for intervention toward improving patients' symptoms and quality of life. We present a critical review of the available evidence for the atopic dermatitis diagnosis and discuss the similarities between atopic dermatitis and allergic contact dermatitis. Because neither flexural predilection nor...... atopy is specific for atopic dermatitis, we conclude that the term atopic dermatitis is a misnomer and propose an etymologic reclassification of atopic dermatitis to "atopy-related" dermatitis. Allergic contact dermatitis can induce an atopic dermatitis-like phenotype, and thus, flexural dermatitis...

  11. Progranulin Overproduction Due to Fli-1 Deficiency Contributes to the Resistance of Dermal Fibroblasts to Tumor Necrosis Factor in Systemic Sclerosis.

    Science.gov (United States)

    Ichimura, Yohei; Asano, Yoshihide; Akamata, Kaname; Noda, Shinji; Taniguchi, Takashi; Takahashi, Takehiro; Toyama, Tetsuo; Tada, Yayoi; Sugaya, Makoto; Sato, Shinichi; Kadono, Takafumi

    2015-12-01

    Progranulin is a growth factor that is active in wound repair and is an antagonist of tumor necrosis factor (TNF) receptors, regulating fibroblast activation, angiogenesis, and inflammation. Because long-standing activation of gene programs related to wound healing is a hallmark of systemic sclerosis (SSc), we sought to investigate the role of progranulin in SSc. Progranulin expression levels in human and murine skin samples were determined by immunohistochemical analysis and quantitative reverse transcription-polymerase chain reaction. The role of progranulin in fibroblast activation was examined using a gene-silencing technique. Progranulin levels in serum obtained from 60 patients with SSc and 16 healthy control subjects were determined by enzyme-linked immunosorbent assay. Progranulin expression was increased in SSc dermal fibroblasts compared with normal dermal fibroblasts, both in vivo and in vitro. Transcription factor Fli-1, a deficiency of which is involved in the activation of SSc dermal fibroblasts, served as a potent repressor of the progranulin gene, and Fli-1(+/-) mice and bleomycin-treated wild-type mice exhibited up-regulated expression of progranulin in dermal fibroblasts. SSc dermal fibroblasts were resistant to the antifibrotic effect of TNF, but this resistance was reversed by gene silencing of progranulin. Serum progranulin levels were elevated in patients with early diffuse cutaneous SSc (dcSSc), especially in those with inflammatory skin symptoms, and were positively correlated with the C-reactive protein level. Progranulin overproduction due to Fli-1 deficiency may contribute to the constitutive activation of SSc dermal fibroblasts by antagonizing the antifibrotic effect of TNF. Progranulin may also be involved in the inflammatory process associated with progressive skin sclerosis in early dcSSc. © 2015, American College of Rheumatology.

  12. Effect of flexural crack on plain concrete beam failure mechanism A numerical simulation

    Directory of Open Access Journals (Sweden)

    Abdoullah Namdar

    2016-03-01

    Full Text Available The flexural failure of plain concrete beam occurs along with development of flexural crack on beam. In this paper by using ABAQUS, mechanism failure of plain concrete beam under three steps have been simulated. The cracking moment has been analytically calculated and applied on the both sides of the fixed beam, and flexural crack has been simulated on beam. Displacement, von Mises, load reaction, displacementcrack length, von Mises-crack length and von Mises-displacement of beams have been graphical depicted. Results indicated that, the flexural crack governs beam mechanism failure and its effects on beam resistance failure. It has been found that the flexural crack in initial stage it developed slowly and changes to be fast at the final stage of collapsing beam due to reduction of the flexural resistance of beam. Increasing mechanical properties of concrete, collapse displacement is reduced.

  13. Ductility of Reinforced Concrete Structures in Flexure

    DEFF Research Database (Denmark)

    Hestbech, Lars

    2013-01-01

    In this thesis, a rotational capacity model for flexural reinforced concrete elements is presented. The model is based on the general assumption, that any other failure mode than bending is prevented by proper design. This includes failure due to shear, anchorage, concentrated loads etc. Likewise...... are not necessarily so. An example shows the applicability of the model and a parametric study shows the advantages of the model compared with code provisions. Finally, improvements of the compression zone modelling is performed in order to include a better performance when concrete crushing is the failure criterion...

  14. Three-Dimensional Glass Monolithic Micro-Flexure Fabricated by Femtosecond Laser Exposure and Chemical Etching

    Directory of Open Access Journals (Sweden)

    Viktor Tielen

    2014-09-01

    Full Text Available Flexures are components of micro-mechanisms efficiently replacing classical multi-part joints found at the macroscale. So far, flexures have been limited to two-dimensional planar designs due to the lack of a suitable three-dimensional micromanufacturing process. Here we demonstrate and characterize a high-strength transparent monolithic three-dimensional flexural component fabricated out of fused silica using non-ablative femtosecond laser processing combined with chemical etching. As an illustration of the potential use of this flexure, we propose a design of a Hoecken linkage entirely made with three-dimensional cross-spring pivot hinges.

  15. Flexural behaviour of RCC beams with externally bonded FRP

    Science.gov (United States)

    Vignesh, S. Arun; Sumathi, A.; Saravana Raja Mohan, K.

    2017-07-01

    The increasing use of carbon and glass fibre reinforced polymer (FRP) sheets for strengthening existing reinforced concrete beams has generated considerable interest in understanding the behavior of the FRP sheets when subjected to bending. The study on flexure includes various parameters like percentage of increase in strength of the member due to the externally bonded Fiber reinforced polymer, examining the crack patterns, reasons of debonding of the fibre from the structure, scaling, convenience of using the fibres, cost effectiveness etc. The present work aims to study experimentally about the reasons behind the failure due to flexure of an EB-FRP concrete beam by studying the various parameters. Deflection control may become as important as flexural strength for the design of FRPreinforced concrete structures. A numerical model is created using FEM software and the results are compared with that of the experiment.

  16. Flexural-Phonon Scattering Induced by Electrostatic Gating in Graphene

    DEFF Research Database (Denmark)

    Gunst, Tue; Kaasbjerg, Kristen; Brandbyge, Mads

    2017-01-01

    Graphene has an extremely high carrier mobility partly due to its planar mirror symmetry inhibiting scattering by the highly occupied acoustic flexural phonons. Electrostatic gating of a graphene device can break the planar mirror symmetry, yielding a coupling mechanism to the flexural phonons......-limiting factor, and show how the carrier density and temperature scaling of the mobility depends on the electrostatic environment. Our findings may explain the high deformation potential for in-plane acoustic phonons extracted from experiments and, furthermore, suggest a direct relation between device symmetry...

  17. Fatigue Strength of Reinforced Concrete Flexural Members | Kuryllo ...

    African Journals Online (AJOL)

    It is well known that reinforced concrete flexural members subjected to cyclic loads behave differently compared with static bending and can collapse due to the fatigue of concrete, reinforcement or both when maximum fatigue stresses of concrete and steel are well below the corresponding static strengths. But up till now ...

  18. EFFECT OF FILLER LOADING ON PHYSICAL AND FLEXURAL PROPERTIES OF RAPESEED STEM/PP COMPOSITES

    Directory of Open Access Journals (Sweden)

    Seyed Majid Zabihzadeh

    2011-03-01

    Full Text Available The objective of the study is to develop a new filler for the production of natural filler thermoplastic composites using the waste rapeseed stalks. The long-term water absorption and thickness swelling behaviors and flexural properties of rapeseed filled polypropylene (PP composites were investigated. Three different contents of filler were tested: 30, 45, and 60 wt%. Results of long-term hygroscopic tests indicated that by the increase in filler content from 30% to 60%, water diffusion absorption and thickness swelling rate parameter increased. A swelling model developed by Shi and Gardner can be used to quantify the swelling rate. The increasing of filler content reduced the flexural strength of the rapeseed/PP composites significantly. In contrast to the flexural strength, the flexural modulus improved with increasing the filler content. The flexural properties of these composites were decreased after the water uptake, due to the effect of the water molecules.

  19. Analysis of flexural wave cloaks

    Directory of Open Access Journals (Sweden)

    Alfonso Climente

    2016-12-01

    Full Text Available This work presents a comprehensive study of the cloak for bending waves theoretically proposed by Farhat et al. [see Phys. Rev. Lett. 103, 024301 (2009] and later on experimentally realized by Stenger et al. [see Phys. Rev. Lett. 108, 014301 (2012]. This study uses a semi-analytical approach, the multilayer scattering method, which is based in the Kirchoff-Love wave equation for flexural waves in thin plates. Our approach was unable to reproduce the predicted behavior of the theoretically proposed cloak. This disagreement is here explained in terms of the simplified wave equation employed in the cloak design, which employed unusual boundary conditions for the cloaking shell. However, our approach reproduces fairly well the measured displacement maps for the fabricated cloak, indicating the validity of our approach. Also, the cloak quality has been here analyzed using the so called averaged visibility and the scattering cross section. The results obtained from both analysis let us to conclude that there is room for further improvements of this type of flexural wave cloak by using better design procedures.

  20. Adjustable bipod flexures for mounting mirrors in a space telescope.

    Science.gov (United States)

    Kihm, Hagyong; Yang, Ho-Soon; Moon, Il Kweon; Yeon, Jeong-Heum; Lee, Seung-Hoon; Lee, Yun-Woo

    2012-11-10

    A new mirror mounting technique applicable to the primary mirror in a space telescope is presented. This mounting technique replaces conventional bipod flexures with flexures having mechanical shims so that adjustments can be made to counter the effects of gravitational distortion of the mirror surface while being tested in the horizontal position. Astigmatic aberration due to the gravitational changes is effectively reduced by adjusting the shim thickness, and the relation between the astigmatism and the shim thickness is investigated. We tested the mirror interferometrically at the center of curvature using a null lens. Then we repeated the test after rotating the mirror about its optical axis by 180° in the horizontal setup, and searched for the minimum system error. With the proposed flexure mount, the gravitational stress at the adhesive coupling between the mirror and the mount is reduced by half that of a conventional bipod flexure for better mechanical safety under launch loads. Analytical results using finite element methods are compared with experimental results from the optical interferometer. Vibration tests verified the mechanical safety and optical stability, and qualified their use in space applications.

  1. Flexural properties of treated and untreated kenaf/epoxy composites

    International Nuclear Information System (INIS)

    Yousif, B.F.; Shalwan, A.; Chin, C.W.; Ming, K.C.

    2012-01-01

    Graphical abstract: Untreated kenaf fibre/epoxy composites. Treated kenaf fibre/epoxy composites. Highlights: ► Treatment of kenaf fibres with 6% NaOH has improved the flexural properties of epoxy composites. ► Interfacial adhesion of the natural fibres is controlled by the microstructure of the fibres. ► Kenaf fibres have a potential to replace glass fibres for flexural applications. -- Abstract: In the current work, flexural properties of unidirectional long kenaf fibre reinforced epoxy (KFRE) composites are studied. The kenaf fibres were prepared into two types as untreated and treated (with 6% NaOH). The failure mechanism and damage features of the materials were categorized with the surface observation by scanning electron microscope (SEM). The results revealed that reinforcement of epoxy with treated kenaf fibres increased the flexural strength of the composite by about 36%, while, untreated fibres introduced 20% improvement. This was mainly due to the high improvement of the chemical treatment (NaOH) on the interfacial adhesion of the fibres and the porosity of the composites which prevented the debonding, detachments or pull out of fibres. For untreated KFRE, the fracture mechanisms were debonding, tearing, detachments and pull out of fibres. The developed composite exhibited superior properties compared to the previous composites based on natural and synthetic fibres.

  2. Renal papillary necrosis

    Science.gov (United States)

    ... asking your provider. Alternative Names Necrosis - renal papillae; Renal medullary necrosis Images Kidney anatomy Kidney - blood and urine flow References Bushinsky DA, Monk RD. Nephrolithiasis and nephrocalcinosis. ...

  3. The Dynamic Performance of Flexural Ultrasonic Transducers

    Directory of Open Access Journals (Sweden)

    Andrew Feeney

    2018-01-01

    Full Text Available Flexural ultrasonic transducers are principally used as proximity sensors and for industrial metrology. Their operation relies on a piezoelectric ceramic to generate a flexing of a metallic membrane, which delivers the ultrasound signal. The performance of flexural ultrasonic transducers has been largely limited to excitation through a short voltage burst signal at a designated mechanical resonance frequency. However, a steady-state amplitude response is not generated instantaneously in a flexural ultrasonic transducer from a drive excitation signal, and differences in the drive characteristics between transmitting and receiving transducers can affect the measured response. This research investigates the dynamic performance of flexural ultrasonic transducers using acoustic microphone measurements and laser Doppler vibrometry, supported by a detailed mechanical analog model, in a process which has not before been applied to the flexural ultrasonic transducer. These techniques are employed to gain insights into the physics of their vibration behaviour, vital for the optimisation of industrial ultrasound systems.

  4. Experimental Study on Flexural Strength of Reinforced Geopolymer Concrete Beams

    OpenAIRE

    Khoa Tan Nguyen; Tuan Anh Le; Kihak Lee

    2016-01-01

    This paper presents the flexural response of Reinforced Geopolymer Concrete (RGPC) beams. A commercial finite element (FE) software ABAQUS has been used to perform a structural behavior of RGPC beams. Using parameters such: stress, strain, Young’s modulus, and Poisson’s ratio obtained from experimental results, a beam model has been simulated in ABAQUS. The results from experimental tests and ABAQUS simulation were compared. Due to friction forces at the supports and loading rollers; slip occ...

  5. Servo Reduces Friction In Flexure Bearing

    Science.gov (United States)

    Clingman, W. Dean

    1991-01-01

    Proposed servocontrol device reduces such resistive torques as stiction, friction, ripple, and cogging in flexure bearing described in LAR-14348, "Flexure Bearing Reduces Startup Friction". Reduces frictional "bump" torque encountered when bearing ball runs into buildup of grease on bearing race. Also used as cable follower to reduce torque caused by cable and hoses when they bend because of motion of bearing. New device includes torquer across ball race. Torquer controlled by servo striving to keep flexure at null, removing torque to outer ring. In effect, device is inner control loop reducing friction, but does not control platforms or any outer-control-loop functions.

  6. Introduction to TAFI - A Matlab® toolbox for analysis of flexural isostasy

    Science.gov (United States)

    Jha, S.; Harry, D. L.; Schutt, D.

    2016-12-01

    The isostatic response of vertical tectonic loads emplaced on thin elastic plates overlying inviscid substrate and the corresponding gravity anomalies are commonly modeled using well established theories and methodologies of flexural analysis. However, such analysis requires some mathematical and coding expertise on part of users. With that in mind, we designed a new interactive Matlab® toolbox called Toolbox for Analysis of Flexural Isostasy (TAFI). TAFI allows users to create forward models (2-D and 3-D) of flexural deformation of the lithosphere and resulting gravity anomaly. TAFI computes Green's Functions for flexure of the elastic plate subjected to point or line loads, and analytical solution for harmonic loads. Flexure due to non-impulsive, distributed 2-D or 3-D loads are computed by convolving the appropriate Green's function with a user-supplied spatially discretized load function. The gravity anomaly associated with each density interface is calculated by using the Fourier Transform of flexural deflection of these interfaces and estimating the gravity in the wavenumber domain. All models created in TAFI are based on Matlab's intrinsic functions and do not require any specialized toolbox, function or library except those distributed with TAFI. Modeling functions within TAFI can be called from Matlab workspace, from within user written programs or from the TAFI's graphical user interface (GUI). The GUI enables the user to model the flexural deflection of lithosphere interactively, enabling real time comparison of model fit with observed data constraining the flexural deformation and gravity, facilitating rapid search for best fitting flexural model. TAFI is a very useful teaching and research tool and have been tested rigorously in graduate level teaching and basic research environment.

  7. Flexural Performance of Transparent Plastic Bar Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Byoungil Kim

    2018-02-01

    Full Text Available In this study, experiments were conducted to derive a mix design for improving the flexural performance of light transparent concrete, which is attracting much attention and interest as an interior and exterior material for buildings, so that it could be easily applied in the field as a non-structural element by securing a lightweight, workability, and economic efficiency through the improvement of the concrete mix design and the use of economical materials for promoting its practical use. It was found that the mixing of polyvinyl alcohol (PVA fiber was effective in improving the consistency by preventing the aggregate from floating due to the mixing of lightweight aggregate with a low specific gravity. The flexural performance test results showed that the load transfer factor (LTF from the concrete matrix to the fiber was highest in the test specimens without plastic bars, followed by those with 5 and 10 mm plastic bars, respectively.

  8. Cracking in Flexural Reinforced Concrete Members

    DEFF Research Database (Denmark)

    Rasmussen, Annette Beedholm; Fisker, Jakob; Hagsten, Lars German

    2017-01-01

    The system of cracks developing in reinforced concrete is in many aspects essential when modelling structures in both serviceability- and ultimate limit state. This paper discusses the behavior concerning crack development in flexural members observed from tests and associates it with two different...... existing models. From the investigations an approach is proposed on how to predict the crack pattern in flexural members involving two different crack systems; primary flexural cracks and local secondary cracks. The results of the approach is in overall good agreement with the observed tests and captures...... the pronounced size effect associated with flexural cracking in which the crack spacing and crack widths are approximately proportional to the depth of the member....

  9. FLEXURAL, TORSIONAL AND DISTORTIONAL BUCKLING OF ...

    African Journals Online (AJOL)

    ABSTRACT. Instability is an important branch of structural mechanics which examines alternate ... equations in V and V representing flexural buckling about the two axis of symmetry; a fully. 4 ..... of Thin-Walled Space Systems, First. Edition ...

  10. Flexural Cracking Behavior Of Steel Fiber Reinforced Concrete Beams

    Directory of Open Access Journals (Sweden)

    Ashraf Abdalkader

    2017-08-01

    Full Text Available Steel fibers are added to concrete due to its ability to improve the tensile strength and control propagation of cracks in reinforced concrete members. Steel fiber reinforced concrete is made of cement fine water and coarse aggregate in addition to steel fibers. In this experimental work flexural cracking behavior of reinforced concrete beams contains different percentage of hooked-end steel fibers with length of 50 mm and equivalent diameter of 0.5 mm was studied. The beams were tested under third-point loading test at 28 days. First cracking load maximum crack width cracks number and load-deflection relations were investigated to evaluate the flexural cracking behavior of concrete beams with 34 MPa target mean strength. Workability wet density compressive and splitting tensile strength were also investigated. The results showed that the flexural crack width is significantly reduced with the addition of steel fibers. Fiber contents of 1.0 resulted in 81 reduction in maximum crack width compared to control concrete without fiber. The results also showed that the first cracking load and maximum load are increased with the addition of steel fibers.

  11. Flexure Based Linear and Rotary Bearings

    Science.gov (United States)

    Voellmer, George M. (Inventor)

    2016-01-01

    A flexure based linear bearing includes top and bottom parallel rigid plates; first and second flexures connecting the top and bottom plates and constraining exactly four degrees of freedom of relative motion of the plates, the four degrees of freedom being X and Y axis translation and rotation about the X and Y axes; and a strut connecting the top and bottom plates and further constraining exactly one degree of freedom of the plates, the one degree of freedom being one of Z axis translation and rotation about the Z axis.

  12. Rotation flexure with temperature controlled modal frequency

    Energy Technology Data Exchange (ETDEWEB)

    Salas, Theodore E.; Barney, Patrick S.; Ison, Aaron M.; Akau, Ronald L; Weir, Nathan

    2017-09-12

    A flexure bearing includes an inner race, an outer race, and a plurality of substantially planar radially extending blades coupled between the inner and outer race. The blades have a thickness that is thinner than a thickness of the inner and outer races. The inner race, outer race, and blades have substantially the same height. At least one heating element is coupled to the inner race and/or the outer race. The heating element is configured to apply heat to the race that it is coupled to in order to tune the flexure bearing.

  13. Flexures for large stroke electrostatic actuation in MEMS

    International Nuclear Information System (INIS)

    Krijnen, B; Brouwer, D M

    2014-01-01

    The stroke of a microelectromechanical systems (MEMS) stage suspended by a flexure mechanism and actuated by electrostatic comb-drives is limited by pull-in. A method to analyze the electrostatic stability of a flexure mechanism and to optimize the stroke with respect to the footprint of flexure mechanisms is presented. Four flexure mechanisms for large stroke are investigated; the standard folded flexure, the slaved folded flexure, the tilted folded flexure and the Watt flexure. Given a certain stroke and load force, the flexures are optimized to have a minimum wafer footprint. From these optimizations it is concluded that the standard folded flexure mechanism is the best flexure mechanism for relatively small strokes (up to ±40 μm) and for larger strokes it is better to use the tilted folded flexure. Several optimized flexure mechanisms have been fabricated and experimentally tested to reach a stroke of ±100 μm. The displacement of the fabricated stages as a function of the actuation voltage could be predicted with 82% accuracy, limited by the fairly large tolerances of our fabrication process. (paper)

  14. Source Illusion Devices for Flexural Lamb Waves Using Elastic Metasurfaces.

    Science.gov (United States)

    Liu, Yongquan; Liang, Zixian; Liu, Fu; Diba, Owen; Lamb, Alistair; Li, Jensen

    2017-07-21

    Inspired by recent demonstrations of metasurfaces in achieving reduced versions of electromagnetic cloaks, we propose and experimentally demonstrate source illusion devices to manipulate flexural waves using metasurfaces. The approach is particularly useful for elastic waves due to the lack of form invariance in usual transformation methods. We demonstrate compact and simple-to-implement metasurfaces for shifting, transforming, and splitting a point source. The effects are measured to be broadband and robust against a change of source positions, with agreement from numerical simulations and the Huygens-Fresnel theory. The proposed method is potentially useful for applications such as nondestructive testing, high-resolution ultrasonography, and advanced signal modulation.

  15. mathematical model for mathematical model for prediction of flexural

    African Journals Online (AJOL)

    eobe

    The paper examined the optimization of flexural strength of a five-component ... flexural strength of concrete was increased by ..... High Performance Concrete”, Fire Safety Journal, Vol. ... Storage, PhD Thesis, University of Nigeria, Nsukka,.

  16. Reactor vessel supported by flexure member

    International Nuclear Information System (INIS)

    Crawford, J.D.; Pankow, B.

    1975-01-01

    A description is given of a reactor pressure vessel which is provided with vertical support means in the form of circumferentially spaced columns upon which the vessel is mounted. The columns are adapted to undergo flexure in order to accommodate the thermally induced displacements experienced by the vessel during operational transients

  17. Psoriasis of the face and flexures.

    NARCIS (Netherlands)

    Kerkhof, P.C.M. van de; Murphy, G.M.; Austad, J.; Ljungberg, A.; Cambazard, F.; Duvold, L.B.

    2007-01-01

    Facial and flexural psoriasis may impair the quality of life of psoriatic patients considerably. For the adequate management of psoriasis it is important to pay attention to lesions at these sensitive sites, which require an approach different to that for lesions on other sites in several respects.

  18. Physical and theoretical modeling of rock slopes against block-flexure toppling failure

    Directory of Open Access Journals (Sweden)

    Mehdi Amini

    2015-12-01

    Full Text Available Block-flexure is the most common mode of toppling failure in natural and excavated rock slopes. In such failure, some rock blocks break due to tensile stresses and some overturn under their own weights and then all of them topple together. In this paper, first, a brief review of previous studies on toppling failures is presented. Then, the physical and mechanical properties of experimental modeling materials are summarized. Next, the physical modeling results of rock slopes with the potential of block-flexural toppling failures are explained and a new analytical solution is proposed for the stability analysis of such slopes. The results of this method are compared with the outcomes of the experiments. The comparative studies show that the proposed analytical approach is appropriate for the stability analysis of rock slopes against block-flexure toppling failure. Finally, a real case study is used for the practical verification of the suggested method.

  19. Synchronic volvulus of splenic flexure and caecum: a very rare cause of large bowel obstruction.

    Science.gov (United States)

    Islam, Shariful; Hosein, Devin; Harnarayan, Patrick; Naraynsingh, Vijay

    2016-01-18

    Colonic volvulus involving the caecum and splenic flexure of the colon is an extremely rare surgical entity and, as a result, it is rarely entertained as a differential diagnosis for large bowel obstruction. The most common site of volvulus is located at the sigmoid colon (75%) followed by caecum (22%). Rare sites of colonic volvulus include the transverse colon (about 2%) and splenic flexure (1-2%). Synchronous double colonic volvulus is very rare. The presentation of this condition can be similar to the signs and symptoms of large bowel obstruction. CT imaging of the abdomen can be diagnostic; however, the diagnosis is often missed due to the rarity of this condition--in such cases, it can only be made at laparotomy. Management of this condition should be expedited to prevent a fatal outcome. We present the case of a 56-year-old woman with synchronous volvulus of the caecum and splenic flexure of the colon. 2016 BMJ Publishing Group Ltd.

  20. Flexural creep behaviour of jute polypropylene composites

    Science.gov (United States)

    Chandekar, Harichandra; Chaudhari, Vikas

    2016-09-01

    Present study is about the flexural creep behaviour of jute fabric reinforced polypropylene (Jute-PP) composites. The PP sheet and alkali treated jute fabric is stacked alternately and hot pressed in compression molding machine to get Jute-PP composite laminate. The flexural creep study is carried out on dynamic mechanical analyzer. The creep behaviour of the composite is modeled using four-parameter Burgers model. Short-term accelerated creep testing is conducted which is later used to predict long term creep behaviour. The feasibility of the construction of a master curve using the time-temperature superposition (TTS) principle to predict long term creep behavior of unreinforced PP and Jute-PP composite is investigated.

  1. Tachykinin receptors in the equine pelvic flexure

    International Nuclear Information System (INIS)

    Sonea, I.M.; Wilson, D.V.; Bowker, R.M.; Robinson, N.E.

    1997-01-01

    Tachykinins, of which substance P (SP) is the prototype, are neuropeptides which are widely distributed in the nervous systems. In the equine gut, SP is present in enteric nerves and is a powerful constrictor of enteric muscle; in other species, SP is also known to have potent vasodilatory and pro-inflammatory effects. The specific effects of SP are determined by the subtype of receptor present in the target tissue. There are 3 known subtypes of tachykinin receptors, distinguished by their relative affinities for SP and other tachykinins. The distribution of SP binding sites in the equine pelvic flexure was determined using 125I-Bolton Hunter SP (I-BHSP) autoradiography. Most I-BHSP binding sites were determined to be saturable and specific, therefore presumably representing tachykinin receptors. The greatest degree of I-BHSP binding occurred over very small vessels, and over the muscularis mucosae; I-BHSP binding was also intense over the circular muscle of the muscularis externa and mucosa, and present, although less intense, over the longitudinal muscle of the muscularis externa. Competition of I-BHSP with specific receptor agonists for binding sites in the equine pelvic flexure were used to determine the subtypes of tachykinin receptors present. The neurokinin-1 receptor subtype predominated in the equine pelvic flexure, followed by the neurokinin-3 receptor subtype

  2. Flexural Free Vibrations of Multistep Nonuniform Beams

    Directory of Open Access Journals (Sweden)

    Guojin Tan

    2016-01-01

    Full Text Available This paper presents an exact approach to investigate the flexural free vibrations of multistep nonuniform beams. Firstly, one-step beam with moment of inertia and mass per unit length varying as I(x=α11+βxr+4 and m(x=α21+βxr was studied. By using appropriate transformations, the differential equation for flexural free vibration of one-step beam with variable cross section is reduced to a four-order differential equation with constant coefficients. According to different types of roots for the characteristic equation of four-order differential equation with constant coefficients, two kinds of modal shape functions are obtained, and the general solutions for flexural free vibration of one-step beam with variable cross section are presented. An exact approach to solve the natural frequencies and modal shapes of multistep beam with variable cross section is presented by using transfer matrix method, the exact general solutions of one-step beam, and iterative method. Numerical examples reveal that the calculated frequencies and modal shapes are in good agreement with the finite element method (FEM, which demonstrates the solutions of present method are exact ones.

  3. Programmed necrosis and necroptosis – molecular mechanisms

    Directory of Open Access Journals (Sweden)

    Agata Giżycka

    2015-12-01

    Full Text Available Programmed necrosis has been proven vital for organism development and homeostasis maintenance. Its regulatory effects on functional activity of the immune system, as well as on pathways regulating the death mechanisms in cells with diminished apoptotic activity, including malignant cells, have been confirmed. There is also increasing evidence indicating necrosis involvement in many human pathologies. Contrary to previous beliefs, necrosis is not only a passive, pathological, gene-independent process. However, the current knowledge regarding molecular regulation of programmed necrosis is scarce. In part this is due to the multiplicity and complexity of signaling pathways involved in programmed necrosis, as well as the absence of specific cellular markers identifying this process, but also the ambiguous and imprecise international terminology. This review presents the current state of the art on molecular mechanisms of programmed necrosis. In particular, its specific and frequent form, necroptosis, is discussed. The role of RIP1 and RIP3 kinases in this process is presented, as well as the diverse pathways induced by ligation of tumor necrosis factor α, to its receptor, TNFR1, i.e. cell survival, apoptosis or necroptosis.

  4. Flexural Behavior of RC Slabs Strengthened in Flexure with Basalt Fabric-Reinforced Cementitious Matrix

    Directory of Open Access Journals (Sweden)

    Sugyu Lee

    2018-01-01

    Full Text Available This paper presents both experimental and analytical research results for predicting the flexural capacity of reinforced concrete (RC slabs strengthened in flexure with basalt fabric-reinforced cementitious matrix (FRCM. A total of 13 specimens were fabricated to evaluate the flexural behavior of RC slabs strengthened with basalt FRCM composite and were tested under four-point loading. The fiber type, tensile reinforcement ratio, and the number of fabric layers were chosen as experimental variables. The maximum load of FRCM-strengthened specimens increased from 11.2% to 98.2% relative to the reference specimens. The energy ratio and ductility of the FRCM-strengthened specimens decreased with the higher amount of fabric and tensile reinforcement. The effective stress level of FRCM fabric can be accurately predicted by a bond strength of ACI 549 and Jung’s model.

  5. Ischemic necrosis and osteochondritis

    International Nuclear Information System (INIS)

    Weissman, S.D.

    1989-01-01

    Osteonecrosis indicates that ischemic death of the cellular constituents of bone and marrow has occurred. Historically, this first was thought to be related to sepsis in the osseous segments. However, continued studies led to the use of the term aseptic necrosis. Subsequent observations indicated that the necrotic areas of bone were not only aseptic, but were also avascular. This led to the terms ischemic necrosis, vascular necrosis and bone infarction. Ischemic necrosis of bone is discussed in this chapter. It results from a significant reduction in or obliteration of blood supply to the affected area. The various bone cells, including osteocytes, osteoclasts, and osteoblasts, usually undergo anoxic death in 12 to 48 hours after blood supply is cut off. The infarct that has thus developed in three-dimensional and can be divided into a number of zones: a central zone of cell death; an area of ischemic injury, most severe near the zone of cell death, and lessening as it moves peripherally; an area of active hyperemia and the zone of normal unaffected tissue. Once ischemic necrosis has begun, the cellular damage provokes an initial inflammatory response, which typically is characterized by vasodilatation, transudation of fluid and fibrin, and local infiltration of flammatory cells. This response can be considered the first stage in repair of the necrotic area

  6. Holocene Flexural Deformation over the Nile Delta: Evidence from Radar Interferometry

    Science.gov (United States)

    Gebremichael, E.; Sultan, M.; Becker, R.

    2017-12-01

    Isostatic adjustment and subsequent subsidence and uplift due to sediment and water loading and unloading mechanisms is one of the major factors that produce regional deformational patterns across river deltas. Using 84 Envisat ASAR scenes that were acquired (2004 - 2010) along three tracks and applying Persistent scatterer (PS) radar interferometric techniques, we documented flexural deformational patterns over the entire Nile Delta (length: 186 km; width: 240 km) of Egypt. The passive continental margin of Africa subsided from Jurassic time onwards due to isostatic loading creating an accommodation space and consequently, the deposition of relatively younger sediments on the oceanic crust. In river deltas, the flexural isostasy model dictates that a subsidence in the oceanic crust side should be balanced by a bulge (uplift) in the flanking regions. Using radar interferometry, we were able to identify the flexural deformation pattern and map its spatial extent over the northern and central Nile Delta region. Findings include: (1) the northern Nile Delta region (block) is separated from the southern delta region by an east-west trending, extensively faulted, hinge line that signifies the boundary between two deformational patterns (subsidence and uplift). It separates the highly subsiding (up to 9.8 mm/yr) northern delta block (up to 85 km long) from the nearly stable (0.4 mm/yr; averaged) southern delta block (up to 91 km long). The hinge line marks the end of the passive continental margin of Africa and the beginning of the oceanic crust of the Mediterranean. (2) We mapped the extent of a 20-40 km wide flexural uplift zone to the south of the hinge line. Within the flexural uplift zone (2.5 mm/yr; averaged), there is a gradual increase in uplift rate reaching peak value (up to 7 mm/yr) near the midpoint of the zone. (3) The uplift rate gradually decreases south of the flexure boundary reaching 0.3 mm/yr at the southern periphery of the delta. (4) The flexural

  7. Laparoscopy of a splenic flexure volvulus

    Directory of Open Access Journals (Sweden)

    Yuichi Sesumi

    2017-09-01

    Full Text Available Splenic flexure volvulus (SFV is a very rare condition that is unlikely to be suspected even when a patient has repeated episodes of abdominal pain and dyschezia. We describe the case of SFV diagnosed and treated laparoscopically in the non-volvulus condition. A 14-year-old boy with no medical history had severe left upper abdominal pain and dyschezia for approximately 1 year. Although contrast enema examination revealed no characteristic findings of volvulus, such as a bird-beak sign, a redundant part of the colon was found to be the site of abdominal pain. We suspected that this part of the colon was the cause of the left upper abdominal pain and performed laparoscopic exploration. The colon at the splenic flexure formed a long loop and was predisposed to twisting; therefore, we performed resection and functional anastomosis of this redundant colon. The postoperative course was uneventful, and the left upper abdominal pain and dyschezia did not recur. Laparoscopic exploration can play a role in patients who are suspected to have recurrent colonic volvulus with radiographic evidence of a redundant portion of the colon, as indicated in our case.

  8. FLEXURAL TOUGHNESS OF STEEL FIBER REINFORCED CONCRETE

    Directory of Open Access Journals (Sweden)

    Fehmi ÇİVİCİ

    2006-02-01

    Full Text Available Fiber concrete is a composite material which has mechanical and physical characteristics unlike plain concrete. One of the important mechanical characteristics of fiber concrete is its energy absorbing capability. This characteristics which is also called toughness, is defined as the total area under the load-deflection curve. A number of composite characteristics such as crack resistance, ductility and impact resistance are related to the energy absorbtion capacity. According to ASTM C 1018 and JSCE SF-4 the calculation of toughness is determined by uniaxial flexural testing. Fiber concrete is often used in plates such as bridge decks, airport pavements, parking areas, subjected to cavitation and erosion. In this paper, toughness has been determined according to ASTM C 1018 and JSCE SF-4 methods by testing beam specimens. Energy absorbing capacities of plain and steel fiber reinforced concrete has been compared by evaluating the results of two methods. Also plain and steel fiber reinforced plate specimens behaviors subjected to biaxial flexure are compared by the loaddeflection curves of each specimen.

  9. Subcutaneous encapsulated fat necrosis

    DEFF Research Database (Denmark)

    Aydin, Dogu; Berg, Jais O

    2016-01-01

    We have described subcutaneous encapsulated fat necrosis, which is benign, usually asymptomatic and underreported. Images have only been published on two earlier occasions, in which the necrotic nodules appear "pearly" than the cloudy yellow surface in present case. The presented image may help...

  10. Long-term deflection and flexural behavior of reinforced concrete beams with recycled aggregate

    International Nuclear Information System (INIS)

    Choi, Won-Chang; Yun, Hyun-Do

    2013-01-01

    Highlights: • Long-term deformation of recycled aggregate concrete beams was examined. • Three beams were monitored for over 380 days. • Influence of recycled aggregate on the long-term performance. • Comparison of that between normal and recycled aggregate concrete beams. - Abstract: This paper presents experimental results on the long-term deformations of recycled aggregate concrete (RAC) beams for over 1 year (380 days) and flexural behavior of RAC beams after exposure to sustained loading. Three reinforced concrete (RC) beam specimens were fabricated with replacement percentage of aggregate (100% natural aggregate, 100% recycled coarse aggregate, and 50% recycled fine aggregate) and subjected to sustained loading that is 50% of the nominal flexural capacity. During the sustained loading period (380 days), the long-term deflection due to creep and shrinkage was recorded and compared with predicted behavior that was determined based on current specifications (ACI 318 Code). After measuring the long-term deflection for 380 days, four-point bending tests were conducted to investigate the flexural behavior of RC beams after exposure to sustained loading and determine any reduction in flexural capacity. A modified equation to predict the long-term deflection values for RC beams with recycled aggregate is proposed, and the experimental results are compared with the predictions calculated using the ACI 318 Code provisions

  11. Compressive strength, flexural strength and water absorption of concrete containing palm oil kernel shell

    Science.gov (United States)

    Noor, Nurazuwa Md; Xiang-ONG, Jun; Noh, Hamidun Mohd; Hamid, Noor Azlina Abdul; Kuzaiman, Salsabila; Ali, Adiwijaya

    2017-11-01

    Effect of inclusion of palm oil kernel shell (PKS) and palm oil fibre (POF) in concrete was investigated on the compressive strength and flexural strength. In addition, investigation of palm oil kernel shell on concrete water absorption was also conducted. Total of 48 concrete cubes and 24 concrete prisms with the size of 100mm × 100mm × 100mm and 100mm × 100mm × 500mm were prepared, respectively. Four (4) series of concrete mix consists of coarse aggregate was replaced by 0%, 25%, 50% and 75% palm kernel shell and each series were divided into two (2) main group. The first group is without POF, while the second group was mixed with the 5cm length of 0.25% of the POF volume fraction. All specimen were tested after 7 and 28 days of water curing for a compression test, and flexural test at 28 days of curing period. Water absorption test was conducted on concrete cube age 28 days. The results showed that the replacement of PKS achieves lower compressive and flexural strength in comparison with conventional concrete. However, the 25% replacement of PKS concrete showed acceptable compressive strength which within the range of requirement for structural concrete. Meanwhile, the POF which should act as matrix reinforcement showed no enhancement in flexural strength due to the balling effect in concrete. As expected, water absorption was increasing with the increasing of PKS in the concrete cause by the porous characteristics of PKS

  12. Enhanced control of a flexure-jointed micromanipulation system using a vision-based servoing approach

    Science.gov (United States)

    Chuthai, T.; Cole, M. O. T.; Wongratanaphisan, T.; Puangmali, P.

    2018-01-01

    This paper describes a high-precision motion control implementation for a flexure-jointed micromanipulator. A desktop experimental motion platform has been created based on a 3RUU parallel kinematic mechanism, driven by rotary voice coil actuators. The three arms supporting the platform have rigid links with compact flexure joints as integrated parts and are made by single-process 3D printing. The mechanism overall size is approximately 250x250x100 mm. The workspace is relatively large for a flexure-jointed mechanism, being approximately 20x20x6 mm. A servo-control implementation based on pseudo-rigid-body models (PRBM) of kinematic behavior combined with nonlinear-PID control has been developed. This is shown to achieve fast response with good noise-rejection and platform stability. However, large errors in absolute positioning occur due to deficiencies in the PRBM kinematics, which cannot accurately capture flexure compliance behavior. To overcome this problem, visual servoing is employed, where a digital microscopy system is used to directly measure the platform position by image processing. By adopting nonlinear PID feedback of measured angles for the actuated joints as inner control loops, combined with auxiliary feedback of vision-based measurements, the absolute positioning error can be eliminated. With controller gain tuning, fast dynamic response and low residual vibration of the end platform can be achieved with absolute positioning accuracy within ±1 micron.

  13. Flexural Properties of PLA Components Under Various Test Condition Manufactured by 3D Printer

    Science.gov (United States)

    Jaya Christiyan, K. G.; Chandrasekhar, U.; Venkateswarlu, K.

    2018-06-01

    Rapid Prototyping (RP) technologies have emerged as a fabrication method to obtain engineering components in the resent past. Desktop 3D printing, also referred as an additive layer manufacturing technology is a powerful method of RP technique that can fabricate 3 dimensional engineering components. In this method, 3D digital data is converted into real product. In the present investigation, Polylactic Acid (PLA) was considered as a starting material. Flexural strength of PLA material was evaluated using 3-point bend test, as per ASTM D790 standard. Specimens with flat (0°) and vertical (90°) orientation were considered. Moreover, layer thicknesses of 0.2, 0.25, and 0.3 mm were considered. To fabricate these specimens, printing speed of 38 and 52 mm/s was maintained. Nozzle diameter of 0.4 mm with 40 % of infill density were used. Based on the experimental results, it was observed that 0° orientation, 38 mm/s printing speed, and 0.2 mm layer thickness resulted maximum flexural strength, as compared to all other specimens. The improved flexural strength was due to the lower layer thickness (0.2 mm) specimens, as compared with other specimens made of 0.25 and 0.30 mm layer thicknesses. It was concluded that flexural strength properties were greatly influenced by lower the layer thickness, printing speed, and orientation.

  14. Performance evaluation of HSC beams with low flexural reinforcement

    Directory of Open Access Journals (Sweden)

    T.M. Elrakib

    2013-04-01

    Full Text Available The main objective of the current research is to establish experimental data for minimum flexural reinforcement, ρmin, of high strength concrete (HSC rectangular beams. Nine full-scale singly reinforced beams with flexural reinforcement ratios varying from 50% to 100% of the minimum limit specified by the ACI 363R-35were tested in flexure. Concrete compressive strengths of 52, 73 and 96.5 MPa were used. The test results including crack patterns, deflections and strains in the tensile flexural steel bars show that a 25% reduction of the ACI 363R-35 limit for the ρmin would result in a satisfactory flexural beam behavior with a reserve flexural parameter (Py,/Pcr ⩾ 1.29 and a displacement ductility index λΔ > 5 for all concrete grades which may lead to good savings in the amount of the flexural reinforcement. Also, it was noted that the displacement ductility index λΔ increased as the concrete compressive strength increased for the same ratio (ρ/ρmin up to 75 MPa and then decreases as fcu increases. For the same concrete compressive strength with low values of flexural reinforcement ratio, ρ, the displacement ductility index λΔ increased as ρ increased. The experimental results of this study were compared with the limits specified by available codes and researches.

  15. Processing, structure and flexural strength of CNT and carbon fibre ...

    Indian Academy of Sciences (India)

    Administrator

    1Department of Mechanical Engineering, Vignan Institute of Technology and Science, Deshmukhi, ... perties include primarily the tensile stress, flexural stress and fracture parameters. However ... The present work is an attempt to bring out the flexural strength ..... lating Materials Annual Book of ASTM Standards American.

  16. 49 CFR 572.85 - Lumbar spine flexure.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Lumbar spine flexure. 572.85 Section 572.85... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES 9-Month Old Child § 572.85 Lumbar spine flexure. (a) When subjected to continuously applied force in accordance with paragraph (b...

  17. Hysteretic Models Considering Axial-Shear-Flexure Interaction

    Science.gov (United States)

    Ceresa, Paola; Negrisoli, Giorgio

    2017-10-01

    Most of the existing numerical models implemented in finite element (FE) software, at the current state of the art, are not capable to describe, with enough reliability, the interaction between axial, shear and flexural actions under cyclic loading (e.g. seismic actions), neglecting crucial effects for predicting the nature of the collapse of reinforced concrete (RC) structural elements. Just a few existing 3D volume models or fibre beam models can lead to a quite accurate response, but they are still computationally inefficient for typical applications in earthquake engineering and also characterized by very complex formulation. Thus, discrete models with lumped plasticity hinges may be the preferred choice for modelling the hysteretic behaviour due to cyclic loading conditions, in particular with reference to its implementation in a commercial software package. These considerations lead to this research work focused on the development of a model for RC beam-column elements able to consider degradation effects and interaction between the actions under cyclic loading conditions. In order to develop a model for a general 3D discrete hinge element able to take into account the axial-shear-flexural interaction, it is necessary to provide an implementation which involves a corrector-predictor iterative scheme. Furthermore, a reliable constitutive model based on damage plasticity theory is formulated and implemented for its numerical validation. Aim of this research work is to provide the formulation of a numerical model, which will allow implementation within a FE software package for nonlinear cyclic analysis of RC structural members. The developed model accounts for stiffness degradation effect and stiffness recovery for loading reversal.

  18. Continuum Mechanics of Beam and Plate Flexure

    DEFF Research Database (Denmark)

    Jönsson, Jeppe

    This text has been written and used during the spring of 1995 for a course on flexural mechanics of beams and plates at Aalborg University. The idea has been to concentrate on basic principles of the theories, which are of importance to the modern structural engineer. Today's structural engineer...... must be acquainted with the classic beam and plate theories, when reading manuals and using modern software tools such as the finite element method. Each chapter includes supplementary theory and derivations enabling consultation of the notes also at a later stage of study. A preliminary chapter...... introduces the modern notation used in textbooks and in research today. It further gives an introduction to three-dimensional continuum mechanics of elastic bodies and the related principles of virtual work. The ideas to give the students a basic understanding of the stresses and strains, the equilibrium...

  19. Tracheal stoma necrosis: a case repor

    Directory of Open Access Journals (Sweden)

    Pak S

    2017-04-01

    Full Text Available Acute tracheal dilatation, due to an overinflated cuff, has been reported early in the course of mechanical ventilation through an endotracheal tube. Tracheal stoma necrosis is a rare complication, but such can accompany acute tracheal dilation. Herein, we report a case of tracheal necrosis 9 days following tracheostomy placement in a 71-year old woman associated with overinflation of the tracheal tube cuff. This case report aims to 1 add to the scant body of knowledge about the diagnosis and management for the patients with tracheal stoma necrosis and 2 raise awareness for error-traps in interpreting diagnostic images, specifically satisfaction of search error, inattentional blindness error, and alliterative error.

  20. Femoral head avascular necrosis

    International Nuclear Information System (INIS)

    Chrysikopoulos, H.; Sartoris, D.J.; Resnick, D.L.; Ashburn, W.; Pretorius, T.

    1988-01-01

    MR imaging has been shown to be more sensitive and specific than planar scintigraphy for avascular necrosis (AVN) of the femoral head. However, experience with single photon emission CT (SPECT) is limited. The authors retrospectively compared 1.5-T MR imaging with SPECT in 14 patients with suspected femoral head AVN. Agreement between MR imaging and SPECT was present in 24 femurs, 14 normal and ten with AVN. MR imaging showed changes of AVN in the remaining four femoral heads. Of these, one was normal and the other three inconclusive for AVN by SPECT. The authors conclude that MR imaging is superior to SPECT for the evaluation of AVN of the hip

  1. Aeroelastic performance evaluation of a flexure box morphing airfoil concept

    Science.gov (United States)

    Pankonien, Alexander M.; Inman, Daniel J.

    2014-04-01

    The flexure-box morphing aileron concept utilizes Macro-Fiber Composites (MFCs) and a compliant box to create a conformal morphing aileron. This work evaluates the impact of the number of MFCs on the performance, power and mass of the aileron by experimentally investigating two different actuator configurations: unimorph and bimorph. Implemented in a NACA 0012 airfoil with 304.8 mm chord, the unimorph and bimorph configurations are experimentally tested over a range of flow speeds from 5 to 20 m/s and angles of attack from -20 to 20 degrees under aerodynamic loads in a wind tunnel. An embedded flexible sensor is installed in the aileron to evaluate the effect of aerodynamic loading on tip position. For both design choices, the effect of actuation on lift, drag and pitching moment coefficients are measured. Finally, the impact on aileron mass and average power consumption due to the added MFCs is considered. The results showed the unimorph exhibiting superior ability to influence flow up to 15 m/s, with equivalent power consumption and lower overall mass. At 20 m/s, the bimorph exhibited superior control over aerodynamic forces and the unimorph experienced significant deformation due to aerodynamic loading.

  2. New research directions in flexural member failure at an interior support (Interaction of web crippling and bending moment)

    NARCIS (Netherlands)

    Hofmeyer, H.; Kerstens, J.G.M.; Snijder, H.H.; Bakker, M.C.M.

    1996-01-01

    Design rules describing failure at an interior support of cold-formed steel flexural members are of an empirical nature. This is probably due to the complex character of the failure mechanisms, which makes an analytical approach difficult. An overview of research on this subject has been made. The

  3. Studying of Compressive, Tensile and Flexural Strength of Concrete by Using Steel Fibers

    Directory of Open Access Journals (Sweden)

    Muslim Abdul-Ameer

    2016-12-01

    Full Text Available This research aims to study the effect of adding steel fibers on the mechanical properties of concrete. Steel fiber has a very significant effect on concrete because it delays the propagation of micro cracks that generate due to loading on concrete members such as beams and slabs, therefore ,it increases the strength of concrete. The steel fiber was used in this study as a percentage of the volume of concrete. Mix proportion was 1: 2:4 (cement: sand: gravel by volume for all mixes and using 0% as (control mix,0.1 %,0.2%,0.5 % and 1.0% of steel fibers, these ratios leads to increase the compressive, tensile ,and flexural strength of concrete, where the improvement in flexural strength was significant

  4. Bonding techniques for flexural strengthening of R.C. beams using CFRP laminates

    Directory of Open Access Journals (Sweden)

    Alaa Morsy

    2013-09-01

    Full Text Available This paper presents an experimental study of an alternative method of attaching FRP laminates to reinforced concrete beams by the way of fasting steel rivets through the FRP laminate and concrete substrate. Five full scale R.C. beams were casted and strengthened in flexural using FRP laminate bonded with conventional epoxy and compared with other beams strengthened with FRP laminate and bonded with fastener “steel rivets” of 50 mm length and 10 mm diameter. Based on experimental evidence the beam strengthened with conventional bonding methods failed due to de-bonding with about 13% increase over the un-strengthened beam. On the other hand, the beams strengthened with FRP laminate and bonded by four steel fastener rivets only failed by de-bonding also but at higher flexural capacity with increase 19% over the un-strengthened beam.

  5. Photogrammetric Assessment of Flexure Induced Cracking of Reinforced Concrete Beams under Service Loads

    DEFF Research Database (Denmark)

    Pease, Bradley Justin; Geiker, Mette Rica; Stang, Henrik

    2006-01-01

    Reinforced concrete structures are known to crack due to restrained shrinkage, temperature gradients, application of load, and expansive reactions. Cracks provide paths for rapid ingress of moisture, chlorides, and other aggressive substances, which may affect the long-term durability...... of the structure. For example, concrete cracks located at the reinforcing steel may contribute to a rapid corrosion initiation and propagation. Previous research has shown that cracked reinforced concrete under static flexural loading may have an increased ingress of chloride ions along the reinforcement....../concrete interface. The aim of this paper is to provide a detailed description of the development of cracks in reinforced concrete under flexural load. Cracking at both realistic service load levels (1.0-1.8 times estimated cracking load) and unrealistically high service load levels (> 0.5 times beam capacity) has...

  6. The fractography analysis of IN718 alloy after three-point flexure fatigue test

    Directory of Open Access Journals (Sweden)

    Belan Juraj

    2018-01-01

    Full Text Available In this study, the high cycle fatigue (HCF properties of IN718 superalloy with given chemical composition were investigated at three-point flexure fatigue test at room temperature. INCONEL alloy 718 is nickel-chromium-iron hardenable alloy and due to its unique combination of mechanical properties (high-strength; corrosion-resistant and so on used for production of heat resistant parts of aero jet engine mostly. Mechanical properties of this alloy are strongly dependent on microstructure and on presence of structural features such are principal strengthening phase gamma double prime, gamma prime and due to its morphology less desired delta phases. The mentioned phases precipitate at various temperature ranges and Nb content as well. The three-point flexure fatigue test was performed on ZWICK/ROELL Amsler 150 HFP 5100 test equipment with approximate loading frequency f=150 Hz. The S – N (Stress – Number of cycles curve was obtained after testing. With the help of scanning electron microscope (SEM, fractography analyses were performed to disclose the fracture features of specimens in different life ranges. The brief comparison of three-point flexure and push-pull fatigue loading modes and its influence on fatigue life is discussed as well.

  7. Resonant metalenses for flexural waves in plates.

    Science.gov (United States)

    Colombi, Andrea

    2016-11-01

    The dispersion curves of a cluster of closely spaced rods supported by a thin plate are characterised by subwavelength bandgaps and slow group velocities induced by local resonance effects. A recent analytical study [Williams, Roux, Rupin, and Kuperman (2015). Phys. Rev. B 91, 104307], has shown how the slow velocity branch depends, amongst other parameters, on the height of the rods that make up the cluster. Such metamaterial, offering easy-to-tune spatial velocity gradients, is a perfect candidate for building gradient index lenses such as Luneburg, Maxwell, and 90° rotating. Here theoretical results are combined with numerical simulations to design and test metalenses for flexural waves. The lenses are obtained by tuning the height of the cluster of rods such that they provide the required refractive index profile. Snapshots and videos from three-dimensional numerical simulations in a narrow band centered at ∼4 kHz are used to analyse the performances of three types of gradient index metalens (Luneburg, Maxwell, and 90° rotating).

  8. The Structure and Flexural Properties of Typha Leaves

    Directory of Open Access Journals (Sweden)

    Jingjing Liu

    2017-01-01

    Full Text Available The Typha leaf has a structure of lightweight cantilever beam, exhibiting excellent mechanical properties with low density. Especially, the leaf blade evolved high strength and low density with high porosity. In this paper, the structure of Typha leaf was characterized by microcomputed tomography (Micro-CT and scanning electron microscopy (SEM, and the relationship with flexural properties was analyzed. The three-point bending test was performed on leaves to examine flexural properties, which indicated that the flexural properties vary from the base to the apex in gradient. The cross-sectional geometry shape of the leaf blade presented a strong influence on the optimized flexural stiffness. The load carrying capacity of the leaf depended on the development level of the epidermal tissue, the vascular bundle, the mechanical tissue, and the geometric properties. The investigation can be the basis for lightweight structure design and the application in the bionic engineering field.

  9. Role of flexural stiffness of leukocyte microvilli in adhesion dynamics

    Science.gov (United States)

    Wu, Tai-Hsien; Qi, Dewei

    2018-03-01

    Previous work reported that microvillus deformation has an important influence on dynamics of cell adhesion. However, the existing studies were limited to the extensional deformation of microvilli and did not consider the effects of their bending deformation on cell adhesion. This Rapid Communication investigates the effects of flexural stiffness of microvilli on the rolling process related to adhesion of leukocytes by using a lattice-Boltzmann lattice-spring method (LLM) combined with adhesive dynamics (AD) simulations. The simulation results reveal that the flexural stiffness of microvilli and their bending deformation have a profound effect on rolling velocity and adhesive forces. As the flexural stiffness of the microvilli decreases, their bending angles increase, resulting in an increase in the number of receptor-ligand bonds and adhesive bonding force and a decrease in the rolling velocity of leukocytes. The effects of flexural stiffness on deformation and adhesion represent crucial factors involved in cell adhesion.

  10. the response prediction of the flexural strength of concrete made

    African Journals Online (AJOL)

    COMPAQ

    2013-07-02

    Jul 2, 2013 ... Using these aggregates, sixty concrete beams of dimensions 600 mm X 150mm X 150 mm were made, .... The sieving was performed by a sieve shaker. .... Table 3a: Regression Analysis of the Flexural Strength Tests Results.

  11. A Case of Unresectable Rectal Necrosis

    Directory of Open Access Journals (Sweden)

    Mohammed Nassif

    2011-01-01

    Full Text Available Introduction. Necrosis of the rectum is an uncommon finding due to abundant collateral vasculature. Its management remains challenging, without clear consensus in the literature. Case Report. We describe a case of a 53-year-old woman with multiple medical comorbidities that presented in septic shock and hematochezia. Colonoscopy revealed ischemic colitis. Conservative management was instituted. At two weeks, she presented evidence of peritonitis. Exploratory laparotomy revealed extensive necrosis of the left colon and rectum. Due to dense inflammation, resection was deemed unsafe. Therefore, a transverse ostomy with mucosal fistula was preformed. Multiple drains were left in place. The patient healed uneventfully. Conclusion. This case illustrates that, if extensive dissection of the distal colon and rectum is unsafe due to the patient's critical condition or technical feasibility, then a diverting ostomy of the proximal viable bowel along with a mucus fistula and good drainage of the abdomen represents an acceptable alternative.

  12. Flexural testing of weld site and HVOF coating characteristics

    CERN Document Server

    Yilbas, Bekir Sami; Sahin, Ahmet

    2014-01-01

    This book provides fundamental understanding and practical application of characteristics of flexural motion in the assessment of the weld size and coating thickness. Some formulations of heat transfer and flexural motion are introduced while displacement and load correlation are used to estimate elastic modules and the size of the heat affected zone as well as the coating thickness. The case studies presented give a practical understanding of weld size and coating thickness characterizations.

  13. Flexural Properties of Activated Carbon Filled Epoxy Nano composites

    International Nuclear Information System (INIS)

    Khalil, H.P.S.A.; Khalil, H.P.S.A.; Alothman, O.Y.; Paridah, M.T.; Zainudin, E.S.

    2014-01-01

    Activated carbon (AC) filled epoxy nano composites obtained by mixing the desired amount of nano AC viz., bamboo stem, oil palm empty fruit bunch, and coconut shell from agricultural biomass with the epoxy resin. Flexural properties of activated carbons filled epoxy nano composites with 1 %, and 5 % filler loading were measured. In terms of flexural strength and modulus, a significant increment was observed with addition of 1 % vol and 5 % vol nano-activated carbon as compared to neat epoxy. The effect of activated carbon treated by two chemical agents (potassium hydroxide and phosphoric acid) on the flexural properties of epoxy nano composites were also investigated. Flexural strength of activated carbon-bamboo stem, activated carbon-oil palm, and activated carbon-coconut shell reinforced epoxy nano composites showed almost same value in case of 5 % potassium hydroxide activated carbon. Flexural strength of potassium hydroxide activated carbon-based epoxy nano composites was higher than phosphoric acid activated carbon. The flexural toughness of both the potassium hydroxide and phosphoric acid activated carbon reinforced composites range between 0.79 - 0.92 J. It attributed that developed activated carbon filled epoxy nano composites can be used in different applications. (author)

  14. The effects of stacking sequence and thermal cycling on the flexural properties of laminate composites of aluminium-epoxy/basalt-glass fibres

    Science.gov (United States)

    Abdollahi Azghan, Mehdi; Eslami-Farsani, Reza

    2018-02-01

    The current study aimed at investigating the effects of different stacking sequences and thermal cycling on the flexural properties of fibre metal laminates (FMLs). FMLs were composed of two aluminium alloy 2024-T3 sheets and epoxy polymer-matrix composites that have four layers of basalt and/or glass fibres with five different stacking sequences. For FML samples the thermal cycle time was about 6 min for temperature cycles from 25 °C to 115 °C. Flexural properties of samples evaluated after 55 thermal cycles and compared to non-exposed samples. Surface modification of aluminium performed by electrochemical treatment (anodizing) method and aluminium surfaces have been examined by scanning electron microscopy (SEM). Also, the flexural failure mechanisms investigated by the optical microscope study of fractured surfaces. SEM images indicated that the porosity of the aluminium surface increased after anodizing process. The findings of the present study showed that flexural modulus were maximum for basalt fibres based FML, minimum for glass fibres based FML while basalt/glass fibres based FML lies between them. Due to change in the failure mechanism of basalt/glass fibres based FMLs that have glass fibres at outer layer of the polymer composite, the flexural strength of this FML is lower than glass and basalt fibres based FML. After thermal cycling, due to the good thermal properties of basalt fibres, flexural properties of basalt fibres based FML structures decreased less than other composites.

  15. Flexural behavior of reinforced concrete beam with polymer coated pumice

    Science.gov (United States)

    Nainggolan, Christin Remayanti; Wijatmiko, Indradi; Wibowo, Ari

    2017-09-01

    Sustainable development has become an important issue due to the increasing consideration of preserving the nature. Many alternative for coarse aggregate replacement have been investigated ranging from natural and fabricated aggregates. In this study, natural aggregate pumice was investigated since it offers lower density that give paramount benefit in reducing total building weight and hence reducing the earthquake excitation effect and optimizing the structural dimension. However, the characteristic of porous surfaces of pumice causes excessive water absorption during concrete mixing process. Therefore, to reduce the additional water, the pumice aggregates were coated with polymer. The tested specimens consisted of normal concrete beams (NCB), uncoated pumice aggregate concrete beam (UPA) and polymer coated pumice aggregate concrete beam (PCP). The objective of the research was to obtain the effect of coating on the pumice aggregate to the flexural behavior of concrete beams. The lateral load-displacement behavior, ductility and collapse mechanism were studied. The results showed that there were only marginal drop on the load-carrying capacity of the pumice aggregate beam compared to those of normal beam. Additionally, the ductility coefficient of specimens UPA and PCP decreased of 11,97% and 14,03% respectively compared to NCB, and the ultimate load capacity decreased less than 1%. Overall, the pumice aggregate showed good characteristic for replacing normal coarse aggregate.

  16. Towards More Sustainable Material Formulations: A Comparative Assessment of PA11-SGW Flexural Performance versus Oil-Based Composites

    Directory of Open Access Journals (Sweden)

    Helena Oliver-Ortega

    2018-04-01

    Full Text Available The replacement of commodity polyolefin, reinforced with glass fiber (GF, by greener alternatives has been a topic of research in recent years. Cellulose fibers have shown, under certain conditions, enough tensile capacities to replace GF, achieving competitive mechanical properties. However, if the objective is the production of environmentally friendlier composites, it is necessary to replace oil-derived polymer matrices by bio-based or biodegradable ones, depending on the application. Polyamide 11 (PA11 is a totally bio-based polyamide that can be reinforced with cellulosic fibers. Composites based on this polymer have demonstrated enough tensile strength, as well as stiffness, to replace GF-reinforced polypropylene (PP. However, flexural properties are of high interest for engineering applications. Due to the specific character of short-fiber-reinforced composites, significant differences are expected between the tensile and flexural properties. These differences encourage the study of the flexural properties of a material prior to the design or development of a new product. Despite the importance of the flexural strength, there are few works devoted to its study in the case of PA11-based composites. In this work, an in-depth study of the flexural strength of PA11 composites, reinforced with Stoneground wood (SGW from softwood, is presented. Additionally, the results are compared with those of PP-based composites. The results showed that the SGW fibers had lower strengthening capacity reinforcing PA11 than PP. Moreover, the flexural strength of PA11-SGW composites was similar to that of PP-GF composites.

  17. Intrinsic low pass filtering improves signal-to-noise ratio in critical-point flexure biosensors

    International Nuclear Information System (INIS)

    Jain, Ankit; Alam, Muhammad Ashraful

    2014-01-01

    A flexure biosensor consists of a suspended beam and a fixed bottom electrode. The adsorption of the target biomolecules on the beam changes its stiffness and results in change of beam's deflection. It is now well established that the sensitivity of sensor is maximized close to the pull-in instability point, where effective stiffness of the beam vanishes. The question: “Do the signal-to-noise ratio (SNR) and the limit-of-detection (LOD) also improve close to the instability point?”, however remains unanswered. In this article, we systematically analyze the noise response to evaluate SNR and establish LOD of critical-point flexure sensors. We find that a flexure sensor acts like an effective low pass filter close to the instability point due to its relatively small resonance frequency, and rejects high frequency noise, leading to improved SNR and LOD. We believe that our conclusions should establish the uniqueness and the technological relevance of critical-point biosensors.

  18. Compressive and flexural strength of concrete containing palm oil biomass clinker and polypropylene fibres

    Science.gov (United States)

    Ibrahim, M. H. Wan; Mangi, Sajjad Ali; Burhanudin, M. K.; Ridzuan, M. B.; Jamaluddin, N.; Shahidan, S.; Wong, YH; Faisal, SK; Fadzil, M. A.; Ramadhansyah, P. J.; Ayop, S. S.; Othman, N. H.

    2017-11-01

    This paper presents the effects of using palm oil biomass (POB) clinker with polypropylene (PP) fibres in concrete on its compressive and flexural strength performances. Due to infrastructural development works, the use of concrete in the construction industry has been increased. Simultaneously, it raises the demand natural sand, which causes depletion of natural resources. While considering the environmental and economic benefits, the utilization of industrial waste by-products in concrete will be the alternative solution of the problem. Among the waste products, one of such waste by-product is the palm oil biomass clinker, which is a waste product from burning processes of palm oil fibres. Therefore, it is important to utilize palm oil biomass clinker as partial replacement of fine aggregates in concrete. Considering the facts, an experimental study was conducted to find out the potential usage of palm oil fibres in concrete. In this study, total 48 number of specimens were cast to evaluate the compressive and flexural strength performances. Polypropylene fibre was added in concrete at the rate of 0.2%, 0.4% and 0.6%, and sand was replaced at a constant rate of 10% with palm oil biomass clinker. The flexural strength of concrete was noticed in the range of 2.25 MPa and 2.29 MPa, whereas, the higher value of flexural strength was recorded with 0.4% polypropylene fibre addition. Hence, these results show that the strength performances of concrete containing POB clinker could be improved with the addition of polypropylene fibre.

  19. Flexural fatigue life prediction of closed hat-section using materially nonlinear axial fatigue characteristics

    Science.gov (United States)

    Razzaq, Zia

    1989-01-01

    Straight or curved hat-section members are often used as structural stiffeners in aircraft. For instance, they are employed as stiffeners for the dorsal skin as well as in the aerial refueling adjacent area structure in F-106 aircraft. The flanges of the hat-section are connected to the aircraft skin. Thus, the portion of the skin closing the hat-section interacts with the section itself when resisting the stresses due to service loads. The flexural fatigue life of such a closed section is estimated using materially nonlinear axial fatigue characteristics. It should be recognized that when a structural shape is subjected to bending, the fatigue life at the neutral axis is infinity since the normal stresses are zero at that location. Conversely, the fatigue life at the extreme fibers where the normal bending stresses are maximum can be expected to be finite. Thus, different fatigue life estimates can be visualized at various distances from the neural axis. The problem becomes compounded further when significant portions away from the neutral axis are stressed into plastic range. A theoretical analysis of the closed hat-section subjected to flexural cyclic loading is first conducted. The axial fatigue characteristics together with the related axial fatigue life formula and its inverted form given by Manson and Muralidharan are adopted for an aluminum alloy used in aircraft construction. A closed-form expression for predicting the flexural fatigue life is then derived for the closed hat-section including materially nonlinear action. A computer program is written to conduct a study of the variables such as the thicknesses of the hat-section and the skin, and the type of alloy used. The study has provided a fundamental understanding of the flexural fatigue life characteristics of a practical structural component used in aircraft when materially nonlinear action is present.

  20. Evaluation of machinability and flexural strength of a novel dental machinable glass-ceramic.

    Science.gov (United States)

    Qin, Feng; Zheng, Shucan; Luo, Zufeng; Li, Yong; Guo, Ling; Zhao, Yunfeng; Fu, Qiang

    2009-10-01

    To evaluate the machinability and flexural strength of a novel dental machinable glass-ceramic (named PMC), and to compare the machinability property with that of Vita Mark II and human enamel. The raw batch materials were selected and mixed. Four groups of novel glass-ceramics were formed at different nucleation temperatures, and were assigned to Group 1, Group 2, Group 3 and Group 4. The machinability of the four groups of novel glass-ceramics, Vita Mark II ceramic and freshly extracted human premolars were compared by means of drilling depth measurement. A three-point bending test was used to measure the flexural strength of the novel glass-ceramics. The crystalline phases of the group with the best machinability were identified by X-ray diffraction. In terms of the drilling depth, Group 2 of the novel glass-ceramics proves to have the largest drilling depth. There was no statistical difference among Group 1, Group 4 and the natural teeth. The drilling depth of Vita MK II was statistically less than that of Group 1, Group 4 and the natural teeth. Group 3 had the least drilling depth. In respect of the flexural strength, Group 2 exhibited the maximum flexural strength; Group 1 was statistically weaker than Group 2; there was no statistical difference between Group 3 and Group 4, and they were the weakest materials. XRD of Group 2 ceramic showed that a new type of dental machinable glass-ceramic containing calcium-mica had been developed by the present study and was named PMC. PMC is promising for application as a dental machinable ceramic due to its good machinability and relatively high strength.

  1. Avascular Necrosis of the Capitate

    OpenAIRE

    Bekele, Wosen; Escobedo, Eva; Allen, Robert

    2011-01-01

    Avascular necrosis of the capitate is a rare entity. The most common reported etiology is trauma. We report a case of avascular necrosis of the capitate in a patient with chronic wrist pain that began after a single episode of remote trauma.

  2. Avascular Necrosis of the Capitate

    Science.gov (United States)

    Bekele, Wosen; Escobedo, Eva; Allen, Robert

    2011-01-01

    Avascular necrosis of the capitate is a rare entity. The most common reported etiology is trauma. We report a case of avascular necrosis of the capitate in a patient with chronic wrist pain that began after a single episode of remote trauma. PMID:22470799

  3. High strength fused silica flexures manufactured by femtosecond laser

    Science.gov (United States)

    Bellouard, Yves; Said, Ali A.; Dugan, Mark; Bado, Philippe

    2009-02-01

    Flexures are mechanical elements used in micro- and precision-engineering to precisely guide the motion of micro-parts. They consist of slender bodies that deform elastically upon the application of a force. Although counter-intuitive at first, fused silica is an attractive material for flexure. Pending that the machining process does not introduce surface flaws that would lead to catastrophic failure, the material has a theoretically high ultimate tensile strength of several GPa. We report on high-aspect ratio fused silica flexures manufactured by femtosecond laser combined with chemical etching. Notch-hinges with thickness as small as twenty microns and aspect ratios comparable to aspect ratios obtained by Deep- Reactive-Ion-Etching (DRIE) were fabricated and tested under different loading conditions. Multiple fracture tests were performed for various loading conditions and the cracks morphologies were analyzed using Scanning Electron Microscopy. The manufactured elements show outstanding mechanical properties with flexural strengths largely exceeding those obtained with other technologies and materials. Fused silica flexures offer a mean to combine integrated optics with micro-mechanics in a single monolithic substrate. Waveguides and mechanical elements can be combined in a monolithic devices opening new opportunities for integrated opto-mechatronics devices.

  4. Flexural strength of structural concrete repaired with HBPMM cement

    International Nuclear Information System (INIS)

    Memon, G.H.; Khaskheli, G.B.; Kumar, A.

    2009-01-01

    To repair damaged concrete structures, Dadabhoy Cement Factory in Sindh has launched a product known as HBPMM (Hi-Bond Polymer Modified Mortar) cement. HBPMM is used to repair various concrete structures in Pakistan but the experimental back up regarding the real performance of the product, as far as flexural strength of concrete is concerned, is not well known yet. This study is thus aimed to investigate the flexural strength of structural concrete repaired with HBPMM compared to that repaired with OPC (Ordinary Portland Cement). In total 32 concrete beams (6x6x18) having compressive strength of 3000 and 5000 psi were manufactured. To obtain flexural strength of the beams, these were splitted by using a UTM (Universal Testing Machine). Beams were then repaired with different applications of HBPMM and OPC. After 28 days of curing, the repaired beams were re-splitted to determine the flexural strength of repaired beams. Results show that both HBPMM and OPC are not very effective. However, the performance of HBPMM remained slightly better than that of OPC. Both OPC and HBPMM remained more efficient in case of 5000 psi concrete than that of 3000 psi concrete. Flexural strength of repaired beams could be increased by increasing application of the repairing material. (author)

  5. Probabilistic Flexural Fatigue in Plain and Fiber-Reinforced Concrete.

    Science.gov (United States)

    Ríos, José D; Cifuentes, Héctor; Yu, Rena C; Ruiz, Gonzalo

    2017-07-07

    The objective of this work is two-fold. First, we attempt to fit the experimental data on the flexural fatigue of plain and fiber-reinforced concrete with a probabilistic model (Saucedo, Yu, Medeiros, Zhang and Ruiz, Int. J. Fatigue, 2013, 48, 308-318). This model was validated for compressive fatigue at various loading frequencies, but not for flexural fatigue. Since the model is probabilistic, it is not necessarily related to the specific mechanism of fatigue damage, but rather generically explains the fatigue distribution in concrete (plain or reinforced with fibers) for damage under compression, tension or flexion. In this work, more than 100 series of flexural fatigue tests in the literature are fit with excellent results. Since the distribution of monotonic tests was not available in the majority of cases, a two-step procedure is established to estimate the model parameters based solely on fatigue tests. The coefficient of regression was more than 0.90 except for particular cases where not all tests were strictly performed under the same loading conditions, which confirms the applicability of the model to flexural fatigue data analysis. Moreover, the model parameters are closely related to fatigue performance, which demonstrates the predictive capacity of the model. For instance, the scale parameter is related to flexural strength, which improves with the addition of fibers. Similarly, fiber increases the scattering of fatigue life, which is reflected by the decreasing shape parameter.

  6. Femoral head necrosis; Hueftkopfnekrose

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, J.; Scheurecker, G.; Scheurecker, A.; Stoeger, A.; Huber, A. [Roentgeninstitut am Schillerpark, Linz (Austria); Hofmann, S. [Orthopaedisches Landeskrankenhaus Stolzalpe (Austria)

    2009-05-15

    The epidemiology and pathohistogenesis of avascular femoral head necrosis has still not been clarified in detail. Because the course of the disease runs in stages and over a long time period nearly always culminates in the necessity for a total hip prosthesis, an exact radiological evaluation is of paramount importance for the treatment. There is a need for a common staging system to enable comparison of different therapy concepts and especially their long-term results. In this article the ARCO staging system is described in full detail, which includes all radiological modalities as well as histopathological alterations. (orig.) [German] Bei der avaskulaeren Femurkopfnekrose handelt es sich um ein Krankheitsbild, dessen Ursachen noch immer nicht vollstaendig geklaert sind. Da die Erkrankung stadienhaft verlaeuft und ueber einen laengeren Zeitraum betrachtet nahezu immer in einem prothetischen Hueftersatz muendet, ist eine genaue radiologische Abklaerung fuer die Behandlung von enormer Bedeutung. Um Langzeiterfolge verschiedener Therapiekonzepte vergleichen zu koennen, sind eine exakte Beschreibung und darauf basierend die Verwendung einer einheitlichen Stadieneinteilung wuenschenswert. In der vorliegenden Arbeit wird die ARCO-Stadieneinteilung im Detail beschrieben, die alle bildgebenden Methoden beruecksichtigt und histopathologische Veraenderungen mit einbezieht. (orig.)

  7. Mandibular bone necrosis after use of paraformaldehyde-containing paste

    Directory of Open Access Journals (Sweden)

    Chi-hwan Lee

    2016-11-01

    Full Text Available Paraformaldehyde has been used in the past as a pulpotomy agent. However, it has a severe cytotoxic effect and may cause alveolar bone necrosis. Depulpin, a devitalizing agent containing 49% paraformaldehyde, is no longer used frequently due to its severe side effects. In the two cases described in the present study, Depulpin was used as a devitalizing agent during root canal treatment. It caused a gradual loss of sensibility in adjacent teeth, gingival necrosis, and osteomyelitis. This case report demonstrates the serious side effects of using a paraformaldehyde-containing paste as a devitalizing agent for pulp, particularly mandibular bone necrosis.

  8. Airway necrosis after salvage esophagectomy

    International Nuclear Information System (INIS)

    Tanaka, Norimitsu; Hokamura, Nobukazu; Tachimori, Yuji

    2010-01-01

    Salvage esophagectomy is the sole curative intent treatment for patients with persistent or recurrent locoregional disease after definitive chemoradiotherapy (CRT) for esophageal carcinoma. However, salvage esophagectomy is a very high-risk operation, and airway necrosis is a fatal complication. Between 1997 and 2007, 49 patients with thoracic esophageal cancer underwent salvage esophagectomy after definitive CRT. We retrospectively compared patients with and without airway necrosis, and investigated operative procedures related to airway necrosis. Airway necrosis occurred in five patients (10.2%), of four patients (80%) died during their hospitalization. Airway necrosis seemed to be closely related to operative procedures, such as resection of bronchial artery and cervical and subcarinal lymph node dissection. Bronchogastric fistula following necrosis of gastric conduit occured in 2 patients reconstructed through posterior mediastinal route. Airway necrosis is a highly lethal complication after salvage esophagectomy. It is important in salvage esophagectomy to take airway blood supply into consideration sufficiently and to reconstruct through retrosternal route to prevent bronchogastric fistula. (author)

  9. Basalt woven fiber reinforced vinylester composites: Flexural and electrical properties

    International Nuclear Information System (INIS)

    Carmisciano, Salvatore; Rosa, Igor Maria De; Sarasini, Fabrizio; Tamburrano, Alessio; Valente, Marco

    2011-01-01

    A preliminary comparative study of basalt and E-glass woven fabric reinforced composites was performed. The fabrics were characterized by the same weave pattern and the laminates tested by the same fiber volume fraction. Results of the flexural and interlaminar characterization are reported. Basalt fiber composites showed higher flexural modulus and apparent interlaminar shear strength (ILSS) in comparison with E-glass ones but also a lower flexural strength and similar electrical properties. With this fiber volume fraction, scanning electron microscopy (SEM) analysis of the fractured surfaces enabled a better understanding both of the failure modes involved and of points of concern. Nevertheless, the results of this study seem promising in view of a full exploitation of basalt fibers as reinforcement in polymer matrix composites (PMCs).

  10. Gastric volvulus with partial and complete gastric necrosis

    Science.gov (United States)

    Shukla, Ram Mohan; Mandal, Kartik Chandra; Maitra, Sujay; Ray, Amit; Sarkar, Ruchirendu; Mukhopadhyay, Biswanath; Bhattacharya, Malay

    2014-01-01

    Here, we report two interesting cases of gastric necrosis in acute gastric volvulus due to eventration of the diaphragm. Both the cases presented with a significant challenge and were managed successfully. The management of the cases is presented and relevant literature is discussed. To the best of our knowledge, this is the first case report of gastric volvulus with gastric necrosis requiring complete and partial gastrectomy in the available English literature. PMID:24604987

  11. Gastric volvulus with partial and complete gastric necrosis

    Directory of Open Access Journals (Sweden)

    Ram Mohan Shukla

    2014-01-01

    Full Text Available Here, we report two interesting cases of gastric necrosis in acute gastric volvulus due to eventration of the diaphragm. Both the cases presented with a significant challenge and were managed successfully. The management of the cases is presented and relevant literature is discussed. To the best of our knowledge, this is the first case report of gastric volvulus with gastric necrosis requiring complete and partial gastrectomy in the available English literature.

  12. Characterization of flexure hinges for the French watt balance experiment

    Directory of Open Access Journals (Sweden)

    Pinot Patrick

    2014-01-01

    Full Text Available In the French watt balance experiment, the translation and rotation functions must have no backlash, no friction, nor the need for lubricants. In addition errors in position and movement must be below 100 nm. Flexure hinges can meet all of these criteria. Different materials, profile shapes and machining techniques have been studied. The flexure pivots have been characterized using three techniques: 1 an optical microscope and, if necessary, a SEM to observe the surface inhomogeneities; 2 a mass comparator to determine the bending stiffness of unloaded pivots; 3 a loaded beam oscillating freely under vacuum to study the dynamic behavior of loaded pivots.

  13. Compressive and flexural strength of cement mortar stabilized with ...

    African Journals Online (AJOL)

    Mortar is a material with wide range of applications in the construction industry. However, plain mortar matrices are usually brittle and often cracks and fails more suddenly than reinforced mortars. In this study, the compressive and flexural strengths of cement mortar stabilized with Raffia Palm Fruit Peel (RPFP) as fibre were ...

  14. Flexure of the Indian plate and intraplate earthquakes

    Indian Academy of Sciences (India)

    The imposition of this stress field on the northward moving Indian plate appears fundamental to explaining the current distribution of intraplate earthquakes and their mechanisms. The current study highlights an outer trough south of the flexural bulge in central India where surface stresses are double the contiguous ...

  15. Effect of surface treatment on flexural strength of zirconia bars

    NARCIS (Netherlands)

    Aboushelib, M.N.; Wang, H.

    2010-01-01

    Statement of problem Clinical and laboratory processing techniques induce damage to the surface of zirconia frameworks, which significantly lessens their strength. Purpose The purpose of this study was to investigate the influence of 3 surface restoration methods on the flexural strength of zirconia

  16. Predicting Flexural Strength of Concretes Incorporating River Gravel ...

    African Journals Online (AJOL)

    In most of these cases the cause of the collapse could be traced to the strength of the construction materials which is usually concrete. Secondly, experimental ... The flexural strength predictions were compared with predictions from an alternative model based on regression analysis. The results of the study show that for the ...

  17. Fatigue life prediction of fiber reinforced concrete under flexural load

    DEFF Research Database (Denmark)

    Zhang, Jun; Stang, Henrik; Li, Victor

    1999-01-01

    This paper presents a semi-analytical method to predict fatigue behavior in flexure of fiber reinforced concrete (FRC) based on the equilibrium of force in the critical cracked section. The model relies on the cyclic bridging law, the so-called stress-crack width relationship under cyclic tensile...

  18. prediction of flexural strength of chikoko pozzolana blended cement

    African Journals Online (AJOL)

    user

    optimize the flexural strength of chikoko pozzolana blended cement concrete using Osadebe's regression function. The ... such as cement [1-3]. Nigeria is blessed with abundance of local building and construction materials such as stones, sand, laterite and timber. However ...... Soil Stabilization”, International Journal of.

  19. Weak-axis flexural buckling of cellular and castellated columns

    NARCIS (Netherlands)

    Sonck, D.; Belis, J.L.I.F.

    Cellular and castellated members are usually produced by performing cutting and rewelding operations on a hot-rolled I-section member. As illustrated in previous work, these operations will influence the residual stresses present in the members in a manner which is detrimental for the flexural

  20. comparative evaluation of the flexural strength of concrete and colcrete

    African Journals Online (AJOL)

    concrete and polymer concrete, from continuous researches being carried out on. 13 ... COMPARATIVE EVALUATION OF THE FLEXURAL STRENGTH OF CONCRETE AND COLCRETE advantage of being able to use larger sizes of ... and low permeability, colcrete has found applications in tunnel linings, dams, bridges.

  1. Strengthening of Steel Columns under Load: Torsional-Flexural Buckling

    Directory of Open Access Journals (Sweden)

    Martin Vild

    2016-01-01

    Full Text Available The paper presents experimental and numerical research into the strengthening of steel columns under load using welded plates. So far, the experimental research in this field has been limited mostly to flexural buckling of columns and the preload had low effect on the column load resistance. This paper focuses on the local buckling and torsional-flexural buckling of columns. Three sets of three columns each were tested. Two sets corresponding to the base section (D and strengthened section (E were tested without preloading and were used for comparison. Columns from set (F were first preloaded to the load corresponding to the half of the load resistance of the base section (D. Then the columns were strengthened and after they cooled, they were loaded to failure. The columns strengthened under load (F had similar average resistance as the columns welded without preloading (E, meaning the preload affects even members susceptible to local buckling and torsional-flexural buckling only slightly. This is the same behaviour as of the tested columns from previous research into flexural buckling. The study includes results gained from finite element models of the problem created in ANSYS software. The results obtained from the experiments and numerical simulations were compared.

  2. Flexural Behavior of Corroded Reinforced Recycled Aggregate Concrete Beams

    Directory of Open Access Journals (Sweden)

    Taoping Ye

    2018-01-01

    Full Text Available Recycling concrete not only reduces the use of virgin aggregate but also decreases the pressure on landfills. As a result, recycled coarse aggregate (RCA is extensively recommended for new construction projects. However, the flexural behavior of corroded reinforced recycled aggregate concrete (RAC beams is uncertain. The experimental research presented in this paper was performed to investigate the flexural behavior of corroded reinforced RAC beams compared to that of corroded reinforced natural aggregate concrete (NAC beams and consequently explore the possibility of using RAC beams in corrosive environments. Four different percentages of RCA in total mass of coarse aggregate in concrete mixtures (0%, 33%, 66%, and 100% and two different concrete strengths (C30, C60 were the governing parameters. The electrochemical method was adopted to accelerate steel corrosion. Full-scale tests were performed on eight simply supported beams until the failure load was reached. Comparison of load-deflection behavior, crack patterns, failure modes, ductility, and ultimate flexural capacity of corroded reinforced NAC and RAC beams was made based on the experimental results obtained. The comparison results show that the flexural behavior of corroded reinforced RAC beams with an appropriate percentage of RCA is satisfactory compared to the behavior of NAC beams.

  3. Environmental effect of water absorption and flexural strength of red ...

    African Journals Online (AJOL)

    The present investigation is aimed at processing a composite using jute fiber and epoxy resin as matrix and red mud as a filler material. The degradation of the composite mechanical properties such as flexural strength has been studied when it is subjected to different environmental conditions. To increase the adhesion ...

  4. Mechanical design of deformation compensated flexural pivots structured for linear nanopositioning stages

    Science.gov (United States)

    Shu, Deming; Kearney, Steven P.; Preissner, Curt A.

    2015-02-17

    A method and deformation compensated flexural pivots structured for precision linear nanopositioning stages are provided. A deformation-compensated flexural linear guiding mechanism includes a basic parallel mechanism including a U-shaped member and a pair of parallel bars linked to respective pairs of I-link bars and each of the I-bars coupled by a respective pair of flexural pivots. The basic parallel mechanism includes substantially evenly distributed flexural pivots minimizing center shift dynamic errors.

  5. fatigue strength of reinforced concrete flexural members

    African Journals Online (AJOL)

    Dr Obe

    1980-03-01

    Mar 1, 1980 ... cyclic loads behave differently compared with static bending and can collapse due to the fatigue of concrete, reinforcement or both when maximum fatigue stresses of ... under low and medium load levels, than under high load ...

  6. Improvement of the cooldown time of LSF 9599 flexure bearing SADA cooler

    NARCIS (Netherlands)

    Mullié, J.; Groep, van der W.; Bruins, P.; Benschop, T.; Koning, de A.; Dam, J.A.M.; Andresen, B.F.; Fulop, G.F.; Norton, P.R.

    2006-01-01

    Thales Cryogenics has presented the LSF 9599 SADA II flexure cooler in 2005. Based on Thales' well-known moving magnet flexure technology, the LSF 9599 complies with the SADA II specification with respect to performance, envelope and mass. Being the first manufacturer offering a full flexure-bearing

  7. Flexural resonance mechanism of thermal transport across graphene-SiO2 interfaces

    Science.gov (United States)

    Ong, Zhun-Yong; Qiu, Bo; Xu, Shanglong; Ruan, Xiulin; Pop, Eric

    2018-03-01

    Understanding the microscopic mechanism of heat dissipation at the dimensionally mismatched interface between a two-dimensional (2D) crystal and its substrate is crucial for the thermal management of devices based on 2D materials. Here, we study the lattice contribution to thermal (Kapitza) transport at graphene-SiO2 interfaces using molecular dynamics (MD) simulations and non-equilibrium Green's functions (NEGF). We find that 78 percent of the Kapitza conductance is due to sub-20 THz flexural acoustic modes, and that a resonance mechanism dominates the interfacial phonon transport. MD and NEGF estimate the classical Kapitza conductance to be hK ≈ 10 to 16 MW K-1 m-2 at 300 K, respectively, consistent with existing experimental observations. Taking into account quantum mechanical corrections, this value is approximately 28% lower at 300 K. Our calculations also suggest that hK scales as T2 at low temperatures (T < 100 K) due to the linear frequency dependence of phonon transmission across the graphene-SiO2 interface at low frequencies. Our study sheds light on the role of flexural acoustic phonons in heat dissipation from graphene to its substrate.

  8. Modified compensation algorithm of lever-arm effect and flexural deformation for polar shipborne transfer alignment based on improved adaptive Kalman filter

    International Nuclear Information System (INIS)

    Wang, Tongda; Cheng, Jianhua; Guan, Dongxue; Kang, Yingyao; Zhang, Wei

    2017-01-01

    Due to the lever-arm effect and flexural deformation in the practical application of transfer alignment (TA), the TA performance is decreased. The existing polar TA algorithm only compensates a fixed lever-arm without considering the dynamic lever-arm caused by flexural deformation; traditional non-polar TA algorithms also have some limitations. Thus, the performance of existing compensation algorithms is unsatisfactory. In this paper, a modified compensation algorithm of the lever-arm effect and flexural deformation is proposed to promote the accuracy and speed of the polar TA. On the basis of a dynamic lever-arm model and a noise compensation method for flexural deformation, polar TA equations are derived in grid frames. Based on the velocity-plus-attitude matching method, the filter models of polar TA are designed. An adaptive Kalman filter (AKF) is improved to promote the robustness and accuracy of the system, and then applied to the estimation of the misalignment angles. Simulation and experiment results have demonstrated that the modified compensation algorithm based on the improved AKF for polar TA can effectively compensate the lever-arm effect and flexural deformation, and then improve the accuracy and speed of TA in the polar region. (paper)

  9. Widespread marrow necrosis during pregnancy

    International Nuclear Information System (INIS)

    Knickerbocker, W.J.; Quenville, N.F.

    1982-01-01

    Recently, a 22-year-old Caucasian female was referred to our Hospital two days post-partum. She had been feeling unwell during the last few days of her pregnancy and complained of multiple aches and pains, worst in the abdomen and lower back. Her admission platelet count was severely depressed and a bone biopsy showed extensive marrow necrosis with viable bony trabeculae. There was no evidence of vasculitis, vascular thrombosis, or malignancy. Widespread marrow necrosis in pregnancy followed by recovery, to our knowledge, has not been previously reported. (orig.)

  10. Implication of snail in metabolic stress-induced necrosis.

    Directory of Open Access Journals (Sweden)

    Cho Hee Kim

    2011-03-01

    Full Text Available Necrosis, a type of cell death accompanied by the rupture of the plasma membrane, promotes tumor progression and aggressiveness by releasing the pro-inflammatory and angiogenic cytokine high mobility group box 1. It is commonly found in the core region of solid tumors due to hypoxia and glucose depletion (GD resulting from insufficient vascularization. Thus, metabolic stress-induced necrosis has important clinical implications for tumor development; however, its regulatory mechanisms have been poorly investigated.Here, we show that the transcription factor Snail, a key regulator of epithelial-mesenchymal transition, is induced in a reactive oxygen species (ROS-dependent manner in both two-dimensional culture of cancer cells, including A549, HepG2, and MDA-MB-231, in response to GD and the inner regions of a multicellular tumor spheroid system, an in vitro model of solid tumors and of human tumors. Snail short hairpin (sh RNA inhibited metabolic stress-induced necrosis in two-dimensional cell culture and in multicellular tumor spheroid system. Snail shRNA-mediated necrosis inhibition appeared to be linked to its ability to suppress metabolic stress-induced mitochondrial ROS production, loss of mitochondrial membrane potential, and mitochondrial permeability transition, which are the primary events that trigger necrosis.Taken together, our findings demonstrate that Snail is implicated in metabolic stress-induced necrosis, providing a new function for Snail in tumor progression.

  11. Investigation of axial positioning for flexural compressors

    Science.gov (United States)

    Riggle, Peter

    1991-01-01

    The testing of the research compressor is presented. The research compressor was assembled and disassembled in order to show the consistency in which the piston and rod could be aligned with a .0004 inch radial gap around the piston. A full set of tests was completed for the first assembly, which is referred to as assembly no. 1. The compressor was disassembled and assembled a second time (assembly no. 2). Assembly no. 2 was only tested statically due to the time constraint. Results are discussed.

  12. Localized surface plate modes via flexural Mie resonances

    KAUST Repository

    Farhat, M.; Chen, P. -Y.; Guenneau, S.; Salama, Khaled N.; Bagci, Hakan

    2017-01-01

    Surface-plasmon polaritons are naturally generated upon excitation of metals with high-frequency electromagnetic waves. However, the concept of spoof plasmons has made it possible to generate plasmoniclike effects in microwave electrodynamics, magnetics, and even acoustics. Similarly, in this paper, the concept of localized surface plate modes (SPMs) is introduced. It is demonstrated that SPMs can be generated on a two-dimensional (clamped or stress-free) cylindrical surface with subwavelength corrugations, which resides on a thin elastic plate, under excitation by an incident flexural plane wave. Numerical characterization of this corrugated rigid structure shows that it is elastically equivalent to a cylindrical scatterer with dispersive but uniformly negative flexural rigidity. This, indeed, suggests that plasmoniclike elastic materials can be engineered with potential applications in various areas including earthquake sensing and elastic imaging and cloaking.

  13. Reinforced flexural elements for TEMP-STRESS Program

    International Nuclear Information System (INIS)

    Marchertas, A.H.; Kennedy, J.M.; Pfeiffer, P.A.

    1987-06-01

    The implementation of reinforced flexural elements into the thermal-mechanical finite element program TEMP-STRESS is described. With explicit temporal integration and dynamic relaxation capabilities in the program, the flexural elements provide an efficient method for the treatment of reinforced structures subjected to transient and static loads. The capability of the computer program is illustrated by the solution of several examples: the simulation of a reinforced concrete beam; simulations of a reinforced concrete containment shell which is subjected to internal pressurization, thermal gradients through the walls, and transient pressure loads. The results of this analysis are relevant in the structural design/safety evaluations of typical reactor containment structures. 22 refs., 13 figs

  14. Localized surface plate modes via flexural Mie resonances

    KAUST Repository

    Farhat, M.

    2017-05-11

    Surface-plasmon polaritons are naturally generated upon excitation of metals with high-frequency electromagnetic waves. However, the concept of spoof plasmons has made it possible to generate plasmoniclike effects in microwave electrodynamics, magnetics, and even acoustics. Similarly, in this paper, the concept of localized surface plate modes (SPMs) is introduced. It is demonstrated that SPMs can be generated on a two-dimensional (clamped or stress-free) cylindrical surface with subwavelength corrugations, which resides on a thin elastic plate, under excitation by an incident flexural plane wave. Numerical characterization of this corrugated rigid structure shows that it is elastically equivalent to a cylindrical scatterer with dispersive but uniformly negative flexural rigidity. This, indeed, suggests that plasmoniclike elastic materials can be engineered with potential applications in various areas including earthquake sensing and elastic imaging and cloaking.

  15. Flexural Behavior of GFRP Tubes Filled with Magnetically Driven Concrete.

    Science.gov (United States)

    Xie, Fang; Chen, Ju; Dong, Xinlong; Feng, Bing

    2018-01-08

    Experimental investigation of GFRP (glass fiber reinforced polymer) tubes that were filled with magnetically driven concrete was carried out to study the flexural behavior of specimens under bending. Specimens having different cross section and lengths were tested. The test specimens were fabricated by filling magnetically driven concrete into the GFRP tubes and the concrete was vibrated using magnetic force. Specimens vibrated using vibrating tube were also tested for comparison. In addition, specimens having steel reinforcing bars and GFRP bars were both tested to study the effect of reinforcing bars on the magnetically driven concrete. The load-displacement curves, load-strain curves, failure mode, and ultimate strengths of test specimens were obtained. Design methods for the flexural stiffness of test specimens were also discussed in this study.

  16. The impact of the lithospheric flexure during the Elsterian glacial maximum on post-/proglacial systems in the southern North Sea area

    DEFF Research Database (Denmark)

    Moreau, Julien; Le Pourhiet, Laetitia; Huuse, Mads

    tunnel valleys). The presence of clinoforms 5080 m above the valley shoulders indicates the potential depth of the lake. The lake geometry was certainly controlled by the lithospheric flexure depression and forebulge due to ice sheet loading, during or after ice sheet recession. The lake levels might...

  17. Effects of specimen size on the flexural strength and Weibull modulus of nuclear graphite IG-110, NBG-18, and PCEA

    International Nuclear Information System (INIS)

    Chi, Se-Hwan

    2015-01-01

    Changes in flexural strength and Weibull modulus due to specimen size were investigated for three nuclear graphite grades, IG-110, NBG-18, and PCEA, using four-point-1/3 point (4-1/3) loading with specimens of three different sizes: 3.18 (Thickness) × 6.35 (Width) × 50.8 (Length), 6.50 (T) × 12.0 (W) × 52.0 (L), 18.0 (T) × 16.0 (W) × 64 (L) (mm) (total: 210 specimens). Results showed some specimen size effects were grade dependent: While NBG-18 (a) showed rather significant specimen size effects (37% difference between the 3 T and 18 T), the differences in IG-110 and PCEA were 7.6–15%. The maximum differences in flexural strength due to specimen size were larger in the PCEA and NBG-18 having larger sized coke particles (medium grain size: >300 μm) than the IG-110 with super fine coke particle size (25 μm). The Weibull modulus showed a data population dependency, in that it decreased with increasing numbers of data used for modulus determination. A good correlation between the fracture surface roughness and the flexural strength was confirmed

  18. Development of delayed radiation necrosis

    International Nuclear Information System (INIS)

    Ohara, ShigFeki; Takagi, Terumasa; Shibata, Taichiro; Nagai, Hajime.

    1983-01-01

    The authors discussed the developing process of delayed radiation necrosis of the brain from the case of a 42-year-old female who developed intracranial hypertension and left hemiparesis 5 and a half years after radiotherapy for pituitary adenoma. The initial sign of radiation necrosis was from a CT scan taken 3 and a half years after radiotherapy showing an irregular low density lesion in the right temporal lobe. CT scan 2 years later demonstrated displacement of the midline structures to the left and a larger low density lesion with partially high density in the right MCA territory that was enhanced with intravenous contrast medium. Recovery after a right temporal lobectomy and administration of steroid hormone were uneventful. Eight months later there were no signs of raised intracranial pressure nor of neurological deficits. Tissues obtained from the right temporal lobe at lobectomy revealed the characteristic changes of delayed radiation necrosis; a mixture of fresh, recent, and old vascular lesions in the same specimen. From these findings, it was speculated that delayed radiation necrosis might initially occur within several years after radiotherapy and might gradually take a progressive and extended course, even in cases whose clinical symptoms develop much later. (author)

  19. Compressive and flexural strength of high strength phase change mortar

    Science.gov (United States)

    Qiao, Qingyao; Fang, Changle

    2018-04-01

    High-strength cement produces a lot of hydration heat when hydrated, it will usually lead to thermal cracks. Phase change materials (PCM) are very potential thermal storage materials. Utilize PCM can help reduce the hydration heat. Research shows that apply suitable amount of PCM has a significant effect on improving the compressive strength of cement mortar, and can also improve the flexural strength to some extent.

  20. Edge chipping and flexural resistance of monolithic ceramics☆

    Science.gov (United States)

    Zhang, Yu; Lee, James J.-W.; Srikanth, Ramanathan; Lawn, Brian R.

    2014-01-01

    Objective Test the hypothesis that monolithic ceramics can be developed with combined esthetics and superior fracture resistance to circumvent processing and performance drawbacks of traditional all-ceramic crowns and fixed-dental-prostheses consisting of a hard and strong core with an esthetic porcelain veneer. Specifically, to demonstrate that monolithic prostheses can be produced with a much reduced susceptibility to fracture. Methods Protocols were applied for quantifying resistance to chipping as well as resistance to flexural failure in two classes of dental ceramic, microstructurally-modified zirconias and lithium disilicate glass–ceramics. A sharp indenter was used to induce chips near the edges of flat-layer specimens, and the results compared with predictions from a critical load equation. The critical loads required to produce cementation surface failure in monolithic specimens bonded to dentin were computed from established flexural strength relations and the predictions validated with experimental data. Results Monolithic zirconias have superior chipping and flexural fracture resistance relative to their veneered counterparts. While they have superior esthetics, glass–ceramics exhibit lower strength but higher chip fracture resistance relative to porcelain-veneered zirconias. Significance The study suggests a promising future for new and improved monolithic ceramic restorations, with combined durability and acceptable esthetics. PMID:24139756

  1. The optimum content of rubber ash in concrete: flexural strength

    Science.gov (United States)

    Senin, M. S.; Shahidan, S.; Shamsuddin, S. M.; Ariffin, S. F. A.; Othman, N. H.; Rahman, R.; Khalid, F. S.; Nazri, F. M.

    2017-11-01

    Discarded scrap tyres have become one of the major environmental problems nowadays. Several studies have been carried out to reuse waste tires as an additive or sand replacement in concrete with appropriate percentages of tire rubber, called as rubberized concrete to solve this problem. The main objectives of this study are to investigate the flexural strength performance of concrete when adding the rubber ash and also to analyse the optimum content of rubber ash in concrete prisms. The performance total of 30 number of concrete prisms in size of 100mm x 100mm x 500 mm were investigated, by partially replacement of rubber ash with percentage of 0%, 3%, 5%, 7% and 9% from the volume of the sand. The flexural strength is increased when percentage of rubber ash is added 3% from control concrete prism, RA 0 for both concrete prism age, 7 days and 28 days with value 1.21% and 0.976% respectively. However, for RA 5, RA 7 and RA 9, the flexural strength was decreased compared to the control for both age, 7 days and 28 days. In conclusion, 3% is the optimum content of rubber ash in concrete prism for both concrete age

  2. Experimental Evaluation of Three Designs of Electrodynamic Flexural Transducers

    Directory of Open Access Journals (Sweden)

    Tobias J. R. Eriksson

    2016-08-01

    Full Text Available Three designs for electrodynamic flexural transducers (EDFT for air-coupled ultrasonics are presented and compared. An all-metal housing was used for robustness, which makes the designs more suitable for industrial applications. The housing is designed such that there is a thin metal plate at the front, with a fundamental flexural vibration mode at ∼50 kHz. By using a flexural resonance mode, good coupling to the load medium was achieved without the use of matching layers. The front radiating plate is actuated electrodynamically by a spiral coil inside the transducer, which produces an induced magnetic field when an AC current is applied to it. The transducers operate without the use of piezoelectric materials, which can simplify manufacturing and prolong the lifetime of the transducers, as well as open up possibilities for high-temperature applications. The results show that different designs perform best for the generation and reception of ultrasound. All three designs produced large acoustic pressure outputs, with a recorded sound pressure level (SPL above 120 dB at a 40 cm distance from the highest output transducer. The sensitivity of the transducers was low, however, with single shot signal-to-noise ratio ( SNR ≃ 15 dB in transmit–receive mode, with transmitter and receiver 40 cm apart.

  3. Uemachi flexure zone investigated by borehole database and numeical simulation

    Science.gov (United States)

    Inoue, N.; Kitada, N.; Takemura, K.

    2014-12-01

    The Uemachi fault zone extending north and south, locates in the center of the Osaka City, in Japan. The Uemachi fault is a blind reverse fault and forms the flexure zone. The effects of the Uemachi flexure zone are considered in constructing of lifelines and buildings. In this region, the geomorphological survey is difficult because of the regression of transgression. Many organizations have carried out investigations of fault structures. Various surveys have been conducted, such as seismic reflection survey in and around Osaka. Many borehole data for construction conformations have been collected and the geotechnical borehole database has been constructed. The investigation with several geological borehole data provides the subsurface geological information to the geotechnical borehole database. Various numerical simulations have been carried out to investigate the growth of a blind reverse fault in unconsolidated sediments. The displacement of the basement was given in two ways. One is based on the fault movement, such as dislocation model, the other is a movement of basement block of hanging wall. The Drucker-Prager and elastic model were used for the sediment and basement, respectively. The simulation with low and high angle fault movements, show the good agree with the actual distribution of the marine clay inferred from borehole data in the northern and southern Uemachi fault flexure zone, respectively. This research is partly funded by the Comprehensive Research on the Uemachi Fault Zone (from FY2010 to FY2012) by The Ministry of Education, Culture, Sports, Science and Technology (MEXT).

  4. Microstructural evaluation and flexural mechanical behavior of pultruded glass fiber composites

    International Nuclear Information System (INIS)

    Chacon, Y.G.; Paciornik, S.; D'Almeida, J.R.M.

    2010-01-01

    Research highlights: → Mosaic images fully characterize the microstructure of heterogeneous materials. → Mosaic images have advantages over microscopy techniques using single fields. → UV and water immersion aging are minimized at the fibers' direction. → UV radiation produced marked changes on the composite surface. - Abstract: The microstructure of a pultruded glass fiber-reinforced composite was fully characterized using digital image analysis. A mosaic technique was used to analyze the entire thickness along specimens' cross-sections, enabling the visualization of the fiber, resin and filler spatial distribution. The advantages of this technique over the usual analysis on single fields, is presented and discussed. The fiber spatial distribution was correlated with flexural mechanical properties as a function of the specimens' position along the length and across the cross section of the composite. The influence of aging by immersion in distilled water and by UV radiation on flexural properties was also analyzed. Minor variation due to aging occurred when longitudinal specimens were tested. Transversally to the fibers, the matrix-dominated composite properties were more affected.

  5. Analysis of the flexural mode response of a novel trimaran by segmented model test

    Directory of Open Access Journals (Sweden)

    Karim Akbari Vakilabadi

    Full Text Available A novel ship concept design is significantly an "adhoc" process. In the preliminary design stage of novel vessels, it is very important to be able to develop an initial estimate of the effects of stiffness and mass distribution on the longitudinal flexural natural frequencies due to different general arrangements in still water at zero speed to satisfy design specifications. For new emerging designs, this estimate has to be made based on a model test. The experiments should also be planned so that scales effects and other features that are not present in full scale case, are minimized. A model with a length of 1.5 meter has been selected. The model was cut into four segments longitudinally and connected by a backbone beam with three elastic hinges joining the four segments. Wet vibration tests were conducted on the model, showed significant influences on the flexural natural frequencies through variations in stiffness and different mass distributions. The whipping frequency was calculated with four degrees of freedom theoretical model to compare with the experimental results. The theoretical model shows a good agreement with the experimental results.

  6. Reactor vessel supported by flexure member

    International Nuclear Information System (INIS)

    Crawford, J.D.; Pankow, B.

    1977-01-01

    According to the present invention there is provided an improved arrangement for supporting a reactor vessel within a containment structure against static and dynamic vertical loadings capable of being imposed as a result of a serious accident as well as during periods of normal plant operation. The support arrangement of the invention is, at the same time, capable of accommodating radial displacements that normally occur between the reactor vessel and the containment structure due to operational transients. The arrangement comprises a plurality of vertical columns connected between the reactor vessel and a support base within the containment structure. The columns are designed to accommodate relative displacements between the vessel and the containment structure by flexing. This eliminates the need for relative sliding movements and thus enables the columns to be securely fixed to the vessel. This elimination of a provision for relative sliding movements avoids the spaces or gaps between the retention members and the retained elements as occurred in prior art arrangements and, concomitantly, the danger of establishing impact forces on the retention members in the event of an accident is reduced. (author)

  7. The relationship between compressive strength and flexural strength of pavement geopolymer grouting material

    Science.gov (United States)

    Zhang, L.; Han, X. X.; Ge, J.; Wang, C. H.

    2018-01-01

    To determine the relationship between compressive strength and flexural strength of pavement geopolymer grouting material, 20 groups of geopolymer grouting materials were prepared, the compressive strength and flexural strength were determined by mechanical properties test. On the basis of excluding the abnormal values through boxplot, the results show that, the compressive strength test results were normal, but there were two mild outliers in 7days flexural strength test. The compressive strength and flexural strength were linearly fitted by SPSS, six regression models were obtained by linear fitting of compressive strength and flexural strength. The linear relationship between compressive strength and flexural strength can be better expressed by the cubic curve model, and the correlation coefficient was 0.842.

  8. Necrosis

    Science.gov (United States)

    ... Updated by: Frank A. Greco, MD, PhD, Director, Biophysical Laboratory, Edith Nourse Rogers Memorial Hospital, Bedford, MA. ... any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should ...

  9. Effect of Maleated Compatibiliser (PBS-g-MA) Addition on the Flexural Properties and Water Absorption of Poly(butylene succinate)/ kenaf Bast Fibre Composites

    International Nuclear Information System (INIS)

    Ahmad, M.Z.T.; Mohd, Z.A.M.; Mat, R.T.; Ahmad, M.Z.T.; Mohd, Z.A.I.; Mat, R.T.; Rahim, S.

    2013-01-01

    Poly(butylene succinate) (PBS) composites with 30 wt.% loading of kenaf bast fibre (KBF) were compatibilised with 5 wt. % maleated PBS (PBS-g-MA). The maleic anhydride (MA) concentration in the compatibiliser was either 3, 5, 7 or 10 phr. In general, the compatibilised composites showed better flexural properties than the un-compatibilised composite. The highest increment in the flexural strength and modulus of 12.7 and 8.9 %, respectively, were obtained with the addition of PBS-g-MA with MA concentration of 5 phr. Compatibilised and un-compatibilised PBS/ KBF composites were immersed in distilled water for 90 days. The absorption of water by all the composites was observed to follow Ficks law. The equilibrium moisture content, M m , of the composites with PBS-g-MA at 3, 5 and 7 phr of MA concentrations was lower than that of the un-compatibilised composite due to improved fiber-matrix interfacial adhesion and reduction of voids content. Both un-compatibilised and compatibilised composites showed dimensional instability after the water absorption. This was probably due to the degradation of the fibre-matrix interfacial adhesion and fibre integrity. The flexural properties of these composites decreased after the water absorption. After re-drying only some of the flexural properties were recovered from plasticizing effect of water. (author)

  10. A Rare Cause of Acute Abdomen: Idiopathic Isolated Cecal Necrosis

    Directory of Open Access Journals (Sweden)

    Ender Özer

    2015-03-01

    Full Text Available Idiopathic isolated cecal necrosis is a clinical problem characterized by right-sided inferior abdominal pain. It is rarely seen, develops due to decreased blood flow to the colon and, imitates acute appendicitis. Its clinical signs are similar to many illnesses causing sensitivity in the right inferior quadrant and, the diagnosis is generally determined during surgery. An 86-year-old male patient presented with the complaints of abdominal pain, trichiniasis, nausea and vomiting. Surgical intervention was decided when physical examination and laboratory results were taken into consideration. After diagnostic laparoscopy, right hemicolectomy was performed because of cecal necrosis. While the mortality and morbidity rates for ischemic bowel disease are high, prognosis for early diagnosed patients with isolated cecal necrosis is better, provided that timely surgical treatment is decided.

  11. Magnetic resonance imaging of the femoral head necrosis

    Energy Technology Data Exchange (ETDEWEB)

    Narita, Shinya; Asada, Kanji; Yoshida, Kenjiro and others

    1986-06-01

    Ten patients with avascular femoral head necrosis and four normal adults were examined by magnetic resonance imaging (MRI). In addition, the relationship between MRI and pathophysiology of three operated-on avascular femoral heads was evaluated. The medullary cavities of the normal femoral heads had a strong signal intensity on the saturation recovery (SR) image due to fat marrow, and the T/sub 1/ relaxation time was 160 +- 11 msec. In avascular femoral head necrosis, the necrotic area had a low signal intensity on the SR image and a prolonged T/sub 1/ relaxation time, while the reactive fibrous area had more prolonged T/sub 1/ relaxation time. For these reasons, MRI was found to show the pathological changes of avascular femoral head necrosis and can be expected to be useful for making early diagnoses and operation planning.

  12. Magnetic resonance imaging of the femoral head necrosis

    International Nuclear Information System (INIS)

    Narita, Shinya; Asada, Kanji; Yoshida, Kenjiro

    1986-01-01

    Ten patients with avascular femoral head necrosis and four normal adults were examined by magnetic resonance imaging (MRI). In addition, the relationship between MRI and pathophysiology of three operated-on avascular femoral heads was evaluated. The medullary cavities of the normal femoral heads had a strong signal intensity on the saturation recovery (SR) image due to fat marrow, and the T 1 relaxation time was 160 ± 11 msec. In avascular femoral head necrosis, the necrotic area had a low signal intensity on the SR image and a prolonged T 1 relaxation time, while the reactive fibrous area had more prolonged T 1 relaxation time. For these reasons, MRI was found to show the pathological changes of avascular femoral head necrosis and can be expected to be useful for making early diagnoses and operation planning. (author)

  13. Tensile and Flexural Test on Kenaf Hybrid Composites

    Science.gov (United States)

    Salleh, Z.; Yunus, S.; Masdek, N. R. N. M.; Taib, Y. M.; Azhar, I. I. S.; Hyie, K. M.

    2018-03-01

    The widely use of synthetic materials like carbon and fiberglass in various industries such as automotive and aircraft has lead to human health and environment problems. Therefore, the use of natural fibres such as kenaf has received higher attention as reinforcement. Kenaf or the scientific name is Hibiscus Cannabinus. L is one of the group of Malvecea plant which in the early days, the application of kenaf served only rope and canvas. However, it has more advantages than synthetic materials such as; widely availaible, renewable, lightweight, non-abbrasiveness during processing, high specific strength, free from health hazard and biodegradeable. This study was carried out to investigate the effects of different arrangement of kenaf and fiberglass composites on Young’s Modulus. The material composite was hardened with polyester resin and their properties was characterized. The tensile and the flexural properties is determined using an Instron universal tensile testing machine and carried out by following ASTM D3039 for tensile and ASTM D790 for a flexural test. The experimental program was designed to correlate the flexural and tensile Young’s Modulus of kenaf and fiberglass composite under the same load condition but different arrangement of kenaf and fiberglass on the mold . The resistance to change in shape was described by the behavior and characteristic of the composite materials. The stiffness or the elastic modulus of the composite material was determined at the end of the experiment. The results obtained show that the [±90FG/0/90/90/0/±90FG] kenaf/fiberglass composite arrangement has the highest elastic value.

  14. Intrinsic Embedded Sensors for Polymeric Mechatronics: Flexure and Force Sensing

    Directory of Open Access Journals (Sweden)

    Leif P. Jentoft

    2014-02-01

    Full Text Available While polymeric fabrication processes, including recent advances in additive manufacturing, have revolutionized manufacturing, little work has been done on effective sensing elements compatible with and embedded within polymeric structures. In this paper, we describe the development and evaluation of two important sensing modalities for embedding in polymeric mechatronic and robotic mechanisms: multi-axis flexure joint angle sensing utilizing IR phototransistors, and a small (12 mm, three-axis force sensing via embedded silicon strain gages with similar performance characteristics as an equally sized metal element based sensor.

  15. Intrinsic embedded sensors for polymeric mechatronics: flexure and force sensing.

    Science.gov (United States)

    Jentoft, Leif P; Dollar, Aaron M; Wagner, Christopher R; Howe, Robert D

    2014-02-25

    While polymeric fabrication processes, including recent advances in additive manufacturing, have revolutionized manufacturing, little work has been done on effective sensing elements compatible with and embedded within polymeric structures. In this paper, we describe the development and evaluation of two important sensing modalities for embedding in polymeric mechatronic and robotic mechanisms: multi-axis flexure joint angle sensing utilizing IR phototransistors, and a small (12 mm), three-axis force sensing via embedded silicon strain gages with similar performance characteristics as an equally sized metal element based sensor.

  16. Flexural Behavior of Aluminum Honeycomb Core Sandwich Structure

    Science.gov (United States)

    Matta, Vidyasagar; Kumar, J. Suresh; Venkataraviteja, Duddu; Reddy, Guggulla Bharath Kumar

    2017-05-01

    This project is concerned with the fabrication and flexural testing of aluminium honey comb sandwich structure which is a special case of composite materials that is fabricated by attaching two thin but stiff skins to a light weight but thick core. The core material is normally low density material but its high thickness provide the sandwich composite with high bonding stiffness. Honeycomb core are classified into two types based on the materials and structures. Hexagonal shape has a unique properties i.e has more bonding strength and less formation time based on the cell size and sheet thickness. Sandwich structure exhibit different properties such as high load bearing capacity at low weight and has excellent thermal insulation. By considering the above properties it has tendency to minimize the structural problem. So honey comb sandwich structure is choosed. The core structure has a different applications such as aircraft, ship interiors, construction industries. As there is no proper research on strength characteristics of sandwich structure. So, we use light weight material to desire the strength. There are different parameters involved in this structure i.e cell size, sheet thickness and core height. In this project we considered 3 level of comparison among the 3 different parameters cell size of 4, 6 and 8 mm, sheet thickness of 0.3, 0.5 and 0.7 mm, and core height of 20,25 and 30 mm. In order to reduce the number of experiment we use taguchi design of experiment, and we select the L8 orthogonal array is the best array for this type of situation, which clearly identifies the parameters by independent of material weight to support this we add the minitab software, to identify the main effective plots and regression equation which involves the individual response and corresponding parameters. Aluminium material is used for the fabrication of Honeycomb sandwich structure among the various grades of aluminium we consider the AL6061 which is light weight material

  17. Pathological investigation of radiation necrosis

    International Nuclear Information System (INIS)

    Nakamura, Nishio; Yoshimura, Noriaki; Ikuta, Fusahiro

    1975-01-01

    The brain and spinal cord of an 18-year-old male, who suffered from cerebellar medulloblastoma with subarachnoid spread, had been irradiated by a large amount of Linac X-ray: 14,450 rads to the lower thoracic segments and 7,400 rads to the lumbar segments. The tumor at the roof of the 4th ventricle had disseminated along the ventricular system but was limited to the subarachnoid space of the cervical spinal cord. No remarkable changes were found in the volume or consistency of the thoracic and lumbar cord. Elasticity of the lower thoracic segment was greatly diminished and the cut surfaces were yellowish white and fragile. Microscopically extensive coagulation necrosis was observed with complete disintegration of myelin and axon. Vascular changes were most prominent in the smaller vessels, eg. hyalinous thickening, concentric cleavage, adventitial fibrosis and edema of small artery perivascular spaces, fibrin thrombi occulusion of arterioles and capillaries, and telangiectasia. In the lumbar spinal cord, moderate neuronal degeneration and protoplasmic astrocytosis were observed. Changes in the lumbar posterior white column were considered to be not only secondary degeneration but also a primary lesion caused by irradiation. Liquefactive necrosis in the gray matter of the cervical cord was thought to be a nonspecific circulatory disturbance because of the absence of vascular changes. Vascular changes were thought to be very important in the histological diagnosis of radiation myelopathy and it was supposed that increased permeability of the vessel walls was a factor in coagulation necrosis. They considered this case to have typical histology of radiation myelopathy. (Evans, J.)

  18. Confinement Effect on Material Properties of RC Beams Under Flexure

    Science.gov (United States)

    Kulkarni, Sumant; Shiyekar, Mukund Ramchandra; Shiyekar, Sandip Mukund

    2017-12-01

    In structural analysis, especially in indeterminate structures, it becomes essential to know the material and geometrical properties of members. The codal provisions recommend elastic properties of concrete and steel and these are fairly accurate enough. The stress-strain curve for concrete cylinder or a cube specimen is plotted. The slope of this curve is modulus of elasticity of plain concrete. Another method of determining modulus of elasticity of concrete is by flexural test of a beam specimen. The modulus of elasticity most commonly used for concrete is secant modulus. The modulus of elasticity of steel is obtained by performing a tension test of steel bar. While performing analysis by any software for high rise building, cross area of plain concrete is taken into consideration whereas effects of reinforcement bars and concrete confined by stirrups are neglected. Present aim of study is to determine elastic properties of reinforced cement concrete beam. Two important stiffness properties such as AE and EI play important role in analysis of high rise RCC building idealized as plane frame. The experimental program consists of testing of beams (model size 150 × 150 × 700 mm) with percentage of reinforcement varying from 0.54 to 1.63% which commensurate with existing Codal provisions of IS:456-2000 for flexural member. The effect of confinement is considered in this study. The experimental results are verified by using 3D finite element techniques.

  19. Fracture toughness of ultra high performance concrete by flexural performance

    Directory of Open Access Journals (Sweden)

    Manolova Emanuela

    2016-01-01

    Full Text Available This paper describes the fracture toughness of the innovative structural material - Ultra High Performance Concrete (UHPC, evaluated by flexural performance. For determination the material behaviour by static loading are used adapted standard test methods for flexural performance of fiber-reinforced concrete (ASTM C 1609 and ASTM C 1018. Fracture toughness is estimated by various deformation parameters derived from the load-deflection curve, obtained by testing simple supported beam under third-point loading, using servo-controlled testing system. This method is used to be estimated the contribution of the embedded fiber-reinforcement into improvement of the fractural behaviour of UHPC by changing the crack-resistant capacity, fracture toughness and energy absorption capacity with various mechanisms. The position of the first crack has been formulated based on P-δ (load- deflection response and P-ε (load - longitudinal deformation in the tensile zone response, which are used for calculation of the two toughness indices I5 and I10. The combination of steel fibres with different dimensions leads to a composite, having at the same time increased crack resistance, first crack formation, ductility and post-peak residual strength.

  20. Progress in Developing Finite Element Models Replicating Flexural Graphite Testing

    International Nuclear Information System (INIS)

    Bratton, Robert

    2010-01-01

    This report documents the status of flexural strength evaluations from current ASTM procedures and of developing finite element models predicting the probability of failure. This work is covered under QLD REC-00030. Flexural testing procedures of the American Society for Testing and Materials (ASTM) assume a linear elastic material that has the same moduli for tension and compression. Contrary to this assumption, graphite is known to have different moduli for tension and compression. A finite element model was developed and demonstrated that accounts for the difference in moduli tension and compression. Brittle materials such as graphite exhibit significant scatter in tensile strength, so probabilistic design approaches must be used when designing components fabricated from brittle materials. ASTM procedures predicting probability of failure in ceramics were compared to methods from the current version of the ASME graphite core components rules predicting probability of failure. Using the ASTM procedures yields failure curves at lower applied forces than the ASME rules. A journal paper was published in the Journal of Nuclear Engineering and Design exploring the statistical models of fracture in graphite.

  1. A Method for Recognizing State of Finger Flexure and Extension

    Science.gov (United States)

    Terado, Toshihiko; Fujiwara, Osamu

    In our country, the handicapped and the elderly people in bed increase rapidly. In the bedridden person’s daily life, there may be limitations in the physical movement and the means of mutual communication. For the support of their comfortable daily lives, therefore, the development of human interface equipment becomes an important task. The equipment of this kind is being already developed by means of laser beam, eye-tracking, breathing motion and myo-electric signals, while the attachment and handling are normally not so easy. In this study, paying attention to finger motion, we have developed human interface equipment easily attached to the body, which enables one to measure the finger flexure and extension for mutual communication. The state of finger flexure and extension is identified by a threshold level analysis from the 3D-locus data for the finger movement, which can be measured through the infrared rays from the LED markers attached to a glove with the previously developed prototype system. We then have confirmed from an experiment that nearly 100% recognition for the finger movement can be achieved.

  2. Distribution of flexural deflection in the worldwide outer rise area

    Science.gov (United States)

    Lin, Zi-Jun; Lin, Jing-Yi; Lin, Yi-Chin; Chin, Shao-Jinn; Chen, Yen-Fu

    2015-04-01

    The outer rise on the fringe of a subduction system is caused by an accreted load on the flexed oceanic lithosphere. The magnitude of the deflection is usually linked to the stress state beard by the oceanic plate. In a coupled subduction zone, the stress is abundantly accumulated across the plate boundary which should affect the flexural properties of the subducted plate. Thus, the variation of the outer rise in shape may reflect the seismogenic characteristics of the subduction system. In this study, we intent to find the correlation between the flexure deflection (Wb) of the outer rise and the subduction zone properties by comparing several slab parameters and the Wb distribution. The estimation of Wb is performed based on the available bathymetry data and the statistic analysis of earthquakes is from the global ISC earthquake catalog for the period of 1900-2015. Our result shows a progressive change of Wb in space, suggesting a robust calculation. The average Wb of worldwise subduction system spreads from 348 to 682 m. No visible distinction in the ranging of Wb was observed for different subduction zones. However, in a weak coupling subduction system, the standard variation of Wb has generally larger value. Relatively large Wb generally occurs in the center of the trench system, whereas small Wb for the two ends of trench. The comparison of Wb and several slab parameters shows that the Wb may be correlated with the maximal magnitude and the number of earthquakes. Otherwise, no clear relationship with other parameters can be obtained.

  3. The nonlinear flexural response of a whole teleost fish: Contribution of scales and skin.

    Science.gov (United States)

    Szewciw, Lawrence; Zhu, Deju; Barthelat, Francois

    2017-12-01

    The scaled skin of fish is an intricate system that provides mechanical protection against hard and sharp puncture, while maintaining the high flexural compliance required for unhindered locomotion. This unusual combination of local hardness and global compliance makes fish skin an interesting model for bioinspired protective systems. In this work we investigate the flexural response of whole teleost fish, and how scales may affect global flexural stiffness. A bending moment is imposed on the entire body of a striped bass (Morone saxatilis). Imaging is used to measure local curvature, to generate moment-curvature curves as function of position along the entire axis of the fish. We find that the flexural stiffness is the highest in the thick middle portion of the fish, and lowest in the caudal and rostral ends. The flexural response is nonlinear, with an initial soft response followed by significant stiffening at larger flexural deformations. Low flexural stiffness at low curvatures promotes efficient swimming, while higher stiffness at high curvatures enables a possible tendon effect, where the mechanical energy at the end of a stroke is stored in the form of strain energy in the fish skin. To assess the contribution of the scales to stiffening we performed flexural tests with and without scales, following a careful protocol to take in account tissue degradation and the effects of temperature. Our findings suggest that scales do not substantially increase the whole body flexural stiffness of teleost fish over ranges of deformations which are typical of swimming and maneuvering. Teleost scales are thin and relatively flexible, so they can accommodate large flexural deformations. This finding is in contrast to the bulkier ganoid scales which were shown in previous reports to have a profound impact of global flexural deformations and swimming in fish like gar or Polypterus. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Avascular necrosis of the hip

    International Nuclear Information System (INIS)

    Lang, P.; Genant, H.K.; Lindquist, T.; Chafetz, N.; Steiger, P.; Sanny, J.; Rhodes, M.L.; Rothman, S.L.G.; Delamarter, R.; Kilgus, D.

    1988-01-01

    T1-weighted (repetition time [TR] = 450 msec, echo time [TE] = 20 msec), T2-weighted (TR = 1,800 msec, TE = 20 and 80 msec), and T2*-weighted gradient-echo gradient recalled acquisition in a steady state, TR = 70 msec, TE = 30 msec, theta = 15 0 ) MR images (General Electric Signa, 1.5 T) were generated in 11 patients with avascular necrosis of the hip. Three-dimensional MR image reconstruction was performed on an independent imaging system (IIS, Dimensional Medicine Inc). Pelvic and femoral bone contours were computed based on either the T1-weighted or the T2*-weighted images. Three-dimensional displays of necrotic zones and areas of granulation tissue were computed on the basis of the T2-weighted images. The tissues were simultaneously displayed in the three-dimensional images using different colors and transparencies. The three-dimensional MR images generated demonstrated the extent of the necrotic zone and adjacent granulation tissue and their position relative to the weight-bearing surface. They may soon prove to be useful in preoperative planning and intraoperative localization of complex surgical interventions in avascular necrosis of the hip

  5. Experimental investigation of span length for flexural test of fiber reinforced polymer composite laminates

    Directory of Open Access Journals (Sweden)

    Akhil Mehndiratta

    2018-01-01

    Full Text Available Testing and evaluation of mechanical properties for FRP (Fiber Reinforced Polymer composite parts play a significant role to qualify it for the end use. Among the mechanical properties, the flexural strength is significant and vital as it may vary with specimen depth, temperature and the test span length. The flexural strength varies for different materials with varying the test span length hence the current work aims to find an optimum span length to test flexural strength for the specimens made of Glass (7781, EC9756 and Carbon (HTA7, G801 prepreg materials. Experiments are conducted as per the ASTM Standard D 790 for flexural test by varying the span lengths to understand the behavior of the flexural strength and flexural modulus. The experimental data were compared with those obtained from the finite element program software Altair Hyper works 14.0. The results indicate that flexural modulus increases with the span length to a point and then it decreases. Thereby, an optimum span length can be obtained for testing flexural strength, which will be useful to the designers and the composite manufacturers to accomplish better standard testing procedures.

  6. Effects of various surface treatments on the biaxial flexural properties of yttria-stabilized zirconia ceramics

    Directory of Open Access Journals (Sweden)

    Teerthesh Jain

    2018-01-01

    Conclusions: Air particle abrasion with CoJet Sand, LTD, and CTs had no negative impact on biaxial flexural strength indeed it increased the biaxial flexural strength. Hence, these surface treatments can be done in routine clinical practice to improve the performance of ceramic restorations.

  7. The use of modal derivatives in determining stroke-dependent frequencies of large stroke flexure hinges

    NARCIS (Netherlands)

    van den Belt, Mieke; Schilder, Jurnan; Valasek, Michael; Sika, Zbynek; Vampola, Tomas

    2017-01-01

    Nowadays, a lot of use is made of large stroke flexure hinges in precision engineering. However, these large stroke flexure hinges typically lose stiffness in supporting direction during deflection. The lowest natural frequency is a commonly used measure for this property. Therefore, in shape and

  8. Effect of flexure beam geometry and material on the displacement of piezo actuated diaphragm for micropump

    Science.gov (United States)

    Roopa, R.; Navin Karanth, P.; Kulkarni, S. M.

    2018-02-01

    In this paper, we present a COMSOL analysis of flexure diaphragm for piezo actuated valveless micropump. Diaphragms play an important role in micropumps, till now plane diaphragms are commonly used in micropumps. Use of compliant flexure hinges in diaphragm and other MEMS application is one of the new approach to achieving high deflection in diaphragm at low operating voltage. Flexures hinges in diaphragm acts as simply supported beam. Out-off plane compliance value and stiffness is considered for the selection of proper flexure for diaphragm. Diaphragm material also plays an important role in the diaphragm central deflection. Factor considered for diaphragm material selection is resilience; it is the ratio of yield stress to static modulus. Higher is the resilience will leads to higher deflection generated, it also imparts good compliance. Based on the resilience beryllium copper, stainless steel and brass materials are selected for diaphragm analysis. Simulations have been performed using COMSOL multiphysics. This study reports the effect of flexure hinge geometry and diaphragm material on the central deflection of diaphragms and compared with existing plane diaphragm. Simulation results illustrates that the deflection of three flexure diaphragm with 2mm width and 2mm length flexure is 6.75µm for stainless steel, 10.89 for beryllium copper and 12.10µm for brass, at 140V which is approximately twice that of plane diaphragm deflection. The maximum in both plane and three flexure diaphragm deflection is obtained for brass diaphragm compared to stainless steel and beryllium copper.

  9. Multi-flexural band gaps in an Euler–Bernoulli beam with lateral local resonators

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ting, E-mail: WT323@mail.nwpu.edu.cn [School of Marine Science and Technology, Northwestern Polytechnical University, Xi' an, Shaanxi, 710072 (China); College of Engineering and Computer Science, The Australian National University, ACT, 2600 (Australia); Sheng, Mei-Ping [School of Marine Science and Technology, Northwestern Polytechnical University, Xi' an, Shaanxi, 710072 (China); Qin, Qing-Hua [College of Engineering and Computer Science, The Australian National University, ACT, 2600 (Australia)

    2016-02-05

    Flexural vibration suppression in an Euler–Bernoulli beam with attached lateral local resonators (LLR) is studied theoretically and numerically. Hamilton's principle and Bloch's theorem are employed to derive the dispersion relation which reveals that two band gaps are generated. Within both band gaps, the flexural waves are partially transformed into longitudinal waves through a four-link-mechanism and totally blocked. The band gaps can be flexibly tuned by changing the geometry parameter of the four-link-mechanism and the spring constants of the resonators. Frequency response function (FRF) from finite element analysis via commercial software of ANSYS shows large flexural wave attenuation within the band gaps and the effect of damping from the LLR substructures which helps smooth and lower the response peaks at the sacrifice of the band gap effect. The existence of the multi-flexural band gaps can be exploited for the design of flexural vibration control of beams. - Highlights: • A metamaterial beam with lateral local resonance is proposed. • The metamaterial beam can generate multi-band gaps for flexural wave suppression. • The substructure can transform the flexural wave into longitudinal wave and absorb the waves. • Damping from different part has different influence on the band gaps. • The design of the metamaterial beam can be used for multi-flexural vibration control.

  10. The influence of resin flexural modulus on the magnitude of ceramic strengthening.

    LENUS (Irish Health Repository)

    Fleming, Garry J P

    2012-07-01

    The aim was to determine the magnitude of ceramic resin-strengthening with resin-based materials with varying flexural moduli using a regression technique to assess the theoretical strengthening at a \\'zero\\' resin-coating thickness. The hypothesis tested was that experimentally, increasing resin flexural modulus results in increased resin-strengthening observed at a theoretical \\'zero\\' resin-coating thickness.

  11. The MISSE 7 Flexural Stress Effects Experiment After 1.5 Years of Wake Space Exposure

    Science.gov (United States)

    Snow, Kate E.; De Groh, Kim K.; Banks, Bruce A.

    2017-01-01

    Low Earth orbit space environment conditions, including ultraviolet radiation, thermal cycling, and atomic oxygen exposure, can cause degradation of exterior spacecraft materials over time. Radiation and thermal exposure often results in bond- breaking and embrittlement of polymers, reducing mechanical strength and structural integrity. An experiment called the Flexural Stress Effects Experiment (FSEE) was flown with the objective of determining the role of space environmental exposure on the degradation of polymers under flexural stress. The FSEE samples were flown in the wake orientation on the exterior of International Space Station for 1.5 years. Twenty-four samples were flown: 12 bent over a 0.375 in. mandrel and 12 were over a 0.25 in. mandrel. This was designed to simulate flight configurations of insulation blankets on spacecraft. The samples consisted of assorted polyimide and fluorinated polymers with various coatings. Half the samples were designated for bend testing and the other half will be tensile tested. A non-standard bend-test procedure was designed to determine the surface strain at which embrittled polymers crack. All ten samples designated for bend testing have been tested. None of the control samples' polymers cracked, even under surface strains up to 19.7%, although one coating cracked. Of the ten flight samples tested, seven show increased embrittlement through bend-test induced cracking at surface strains from 0.70%to 11.73%. These results show that most of the tested polymers are embrittled due to space exposure, when compared to their control samples. Determination of the extent of space induced embrittlement of polymers is important for designing durable spacecraft.

  12. In vitro/in silico investigation of failure criteria to predict flexural strength of composite resins.

    Science.gov (United States)

    Yamaguchi, Satoshi; Mehdawi, Idris Mohamed; Sakai, Takahiko; Abe, Tomohiro; Inoue, Sayuri; Imazato, Satoshi

    2018-01-30

    The aim of this study was to investigate a failure criterion to predict flexural strengths of composite resins (CR) by three-dimensional finite element analysis (3D-FEA). Models of flexural strength for test specimens of CR and rods comprising a three-point loading were designed. Calculation of Young's moduli and Poisson's ratios of CR were conducted using a modified McGee-McCullough model. Using the experimental CR, flexural strengths were measured by three-point bending tests with crosshead speed 1.0 mm/min and compared with the values determined by in silico analysis. The flexural strengths of experimental CR calculated using the maximum principal strain significantly correlated with those obtained in silico amongst the four types of failure criteria applied. The in silico analytical model established in this study was found to be effective to predict the flexural strengths of CR incorporating various silica filler contents by maximum principal strain.

  13. Multi-objective optimization of a type of ellipse-parabola shaped superelastic flexure hinge

    Directory of Open Access Journals (Sweden)

    Z. Du

    2016-05-01

    Full Text Available Flexure hinges made of superelastic materials is a promising candidate to enhance the movability of compliant mechanisms. In this paper, we focus on the multi-objective optimization of a type of ellipse-parabola shaped superelastic flexure hinge. The objective is to determine a set of optimal geometric parameters that maximizes the motion range and the relative compliance of the flexure hinge and minimizes the relative rotation error during the deformation as well. Firstly, the paper presents a new type of ellipse-parabola shaped flexure hinge which is constructed by an ellipse arc and a parabola curve. Then, the static responses of superelastic flexure hinges are solved via non-prismatic beam elements derived by the co-rotational approach. Finite element analysis (FEA and experiment tests are performed to verify the modeling method. Finally, a multi-objective optimization is performed and the Pareto frontier is found via the NSGA-II algorithm.

  14. Experimental and theoretical assessment of flexural properties of hybrid natural fibre composites

    DEFF Research Database (Denmark)

    Raghavalu Thirumalai, Durai Prabhakaran; Toftegaard, Helmuth Langmaack; Markussen, Christen Malte

    2014-01-01

    The concept of hybridization of natural fibre composites with synthetic fibres is attracting increasing scientific attention. The present study addresses the flexural properties of hybrid flax/glass/epoxy composites to demonstrate the potential benefits of hybridization. The study covers both...... experimental and theoretical assessments. Composite laminates with different hybrid fibre mixing ratios and different layer configurations were manufactured, and their volumetric composition and flexural properties were measured. The relationship between volume fractions in the composites is shown to be well...... predicted as a function of the hybrid fibre mixing ratio. The flexural modulus of the composites is theoretically assessed by using micromechanical models and laminate theory. The model predictions are compared with the experimentally determined flexural properties. Both approaches show that the flexural...

  15. Comparison of Flexural Strength of Different CAD/CAM PMMA-Based Polymers.

    Science.gov (United States)

    Alp, Gülce; Murat, Sema; Yilmaz, Burak

    2018-01-28

    To compare the flexural strength of different computer-aided design/computer-aided manufacturing (CAD/CAM) poly(methyl methacrylate)-based (PMMA) polymers and conventional interim resin materials after thermocycling. Rectangular-shaped specimens (n = 15, for each material) (25 × 2 × 2 mm 3 ) were fabricated from 3 CAD/CAM PMMA-based polymers (Telio CAD [T]; M-PM-Disc [M]; Polident-PMMA [P]), 1 bis-acrylate composite resin (Protemp 4 [PT]), and 1 conventional PMMA (ArtConcept Artegral Dentine [C]) according to ISO 10477:2004 Standards (Dentistry-Polymer-Based Crown and Bridge Materials). The specimens were subjected to 10,000 thermocycles (5 to 55°C). Three-point flexural strength of the specimens was tested in a universal testing machine at a 1.0 mm/min crosshead speed, and the flexural strength data (σ) were calculated (MPa). The flexural strength values were statistically analyzed using 1-way ANOVA, and Tukey HSD post-hoc test for multiple comparisons (α = 0.05). Flexural strength values ranged between 66.1 ± 13.1 and 131.9 ± 19.8 MPa. There were significant differences among the flexural strengths of tested materials, except for between T and P CAD/CAM PMMA-based polymers (p > 0.05). CAD/CAM PMMA-based polymer M had the highest flexural strength and conventional PMMA had the lowest (p CAD/CAM PMMA-based T and P polymers had significantly higher flexural strength than the bis-acrylate composite resin (p CAD/CAM PMMA-based M (p CAD/CAM PMMA-based polymers was greater than the flexural strength of bis-acrylate composite resin, which had a greater flexural strength compared to conventional PMMA resin. © 2018 by the American College of Prosthodontists.

  16. Effect of the application of surface treatments before and after sintering on the flexural strength, phase transformation and surface topography of zirconia.

    Science.gov (United States)

    Kurtulmus-Yilmaz, Sevcan; Aktore, Huseyin

    2018-05-01

    To evaluate the effects of airborne-particle abrasion (APA) and Er,Cr:YSGG laser irradiation on 4-point-flexural strength, phase transformation and morphologic changes of zirconia ceramics treated at pre-sintered or post-sintered stage. Three hundred and forty-two bar shaped zirconia specimens were milled with different sizes according to the flexural strength test (n = 10), X-ray diffraction (XRD) (n = 4) and field emission scanning electron microscope (FE-SEM) (n = 4) analyses. For each test protocol, specimens were divided into 4 main groups whether the surface treatments applied before or after sintering and whether the specimens received heat treatment or not as pre-sintered, post-sintered no-heat and post-sintered heat-treated groups, and a group was served as control. Main groups were further divided into 6 equal subgroups according to surface treatment method applied (2 W-, 3 W-, 4 W-, 5 W-, 6 W-laser irradiations and APA). Surface treatments were applied to pre-sintered groups before sintering and to post-sintered groups after sintering. Post-sintered heat-treated groups were subjected to veneer ceramic firing simulation after surface treatments. Flexural strength and flexural modulus values were statistically analysed and monoclinic phase content was calculated. Weibull analysis was used to evaluate strength reliability and fractographic analysis was conducted. Highest flexural strength values were detected at post-sintered no-heat APA and 4W-laser groups (P SEM images pre-sintered groups. Application of surface treatments at pre-sintered stage may be detrimental for zirconia ceramics in terms of flexural strength. Treating the surface of zirconia ceramic before sintering process is not recommended due to significant decrease in flexural strength values. 2 W-4 W Er,Cr:YSGG laser irradiations can be regarded as alternative surface treatment methods when zirconia restoration would be subjected to veneer ceramic firing procedures

  17. Tension stiffening in partially prestressed concrete flexural members

    International Nuclear Information System (INIS)

    Oukaili, K. N.

    2000-01-01

    Concrete tensile strength is not being zero, cracking does not extend to the neutral axis as assumed in standard cracked section analysis. In addition, un cracked concrete, which exists above the crack tip in the tension zone, contributes to the stiffness of the member. This paper discusses the influence of concrete tensile stress below the neut ural axis position at the cracked section on the tension stiffening phenomenon and deflection of progressively cracking partially prestressed concrete flexural members. The computation of the neutral axis location, which takes into consideration the effect of concrete in tension, can be achieved by solving iteratively tow simultaneous equation derived from forces and moments equilibrium, strain compatibility and linear stress - strain relationship in concrete across the section depth. Once the section depth after cracking is known, it can be used to calculate the effective moment of inertia for deflection analysis. (author). 13 refs., 3 figs., 1 table

  18. Ice-Shelf Tidal Flexure and Subglacial Pressure Variations

    Science.gov (United States)

    Walker, Ryan T.; Parizek, Byron R.; Alley, Richard B.; Anandakrishnan, Sridhar; Riverman, Kiya L.; Christianson, Knut

    2013-01-01

    We develop a model of an ice shelf-ice stream system as a viscoelastic beam partially supported by an elastic foundation. When bed rock near the grounding line acts as a fulcrum, leverage from the ice shelf dropping at low tide can cause significant (approx 1 cm) uplift in the first few kilometers of grounded ice.This uplift and the corresponding depression at high tide lead to basal pressure variations of sufficient magnitude to influence subglacial hydrology.Tidal flexure may thus affect basal lubrication, sediment flow, and till strength, all of which are significant factors in ice-stream dynamics and grounding-line stability. Under certain circumstances, our results suggest the possibility of seawater being drawn into the subglacial water system. The presence of sea water beneath grounded ice would significantly change the radar reflectivity of the grounding zone and complicate the interpretation of grounded versus floating ice based on ice-penetrating radar observations.

  19. Targeting of regulated necrosis in kidney disease

    Directory of Open Access Journals (Sweden)

    Diego Martin-Sanchez

    2018-03-01

    Full Text Available The term acute tubular necrosis was thought to represent a misnomer derived from morphological studies of human necropsies and necrosis was thought to represent an unregulated passive form of cell death which was not amenable to therapeutic manipulation. Recent advances have improved our understanding of cell death in acute kidney injury. First, apoptosis results in cell loss, but does not trigger an inflammatory response. However, clumsy attempts at interfering with apoptosis (e.g. certain caspase inhibitors may trigger necrosis and, thus, inflammation-mediated kidney injury. Second, and most revolutionary, the concept of regulated necrosis emerged. Several modalities of regulated necrosis were described, such as necroptosis, ferroptosis, pyroptosis and mitochondria permeability transition regulated necrosis. Similar to apoptosis, regulated necrosis is modulated by specific molecules that behave as therapeutic targets. Contrary to apoptosis, regulated necrosis may be extremely pro-inflammatory and, importantly for kidney transplantation, immunogenic. Furthermore, regulated necrosis may trigger synchronized necrosis, in which all cells within a given tubule die in a synchronized manner. We now review the different modalities of regulated necrosis, the evidence for a role in diverse forms of kidney injury and the new opportunities for therapeutic intervention. Resumen: La idea de que el término necrosis tubular aguda supone una denominación inapropiada se deriva de estudios morfológicos de necropsias humanas. La opinión generalizada ha sido que la necrosis representa una forma pasiva de muerte celular no regulada que no es susceptible de manipulación terapéutica. Los recientes avances han mejorado nuestra comprensión de la muerte celular en la lesión renal aguda. En primer lugar, la apoptosis origina una pérdida celular, pero no desencadena una respuesta inflamatoria. Sin embargo, los intentos rudimentarios de interferir en la apoptosis

  20. Evolving lithospheric flexure and paleotopography of the Pyrenean Orogen from 3D flexural modeling and basin analysis

    Science.gov (United States)

    Curry, M. E.; van der Beek, P.; Huismans, R. S.; Muñoz, J. A.

    2017-12-01

    The Pyrenees are an asymmetric, doubly-vergent orogen with retro- and pro- foreland basins that preserve a record of deformation since the Mesozoic. The extensive research and exploration efforts on the mountain belt and flanking foreland basins provide an exceptional dataset for investigating geodynamics and surface processes over large spatial and temporal scales in western Europe. We present the results of a numerical modeling study investigating the spatio-temporal variation in lithospheric flexure in response to the developing orogen. We employ a finite element method to model the 3D flexural deformation of the lithosphere beneath the Pyrenean orogen since the onset of convergence in the late Cretaceous. Using subsurface, geophysical, and structural data, we describe the evolving geometry of both the French Aquitaine and Spanish Ebro foreland basins at the present (post-orogenic), the mid-Eocene (peak orogenic), the Paleocene (early orogenic), and the end of the Cretaceous (pre- to early orogenic). The flexural modeling provides insight into how both the rigidity of the lithosphere and the paleotopographic load have varied over the course of orogenesis to shape the basin geometry. We find that the overriding European plate has higher rigidity than the subducting Iberian plate, with modern Effective Elastic Thickness (EET) values of 20 ± 2 and 12 ± 2 km, respectively. Modeling indicates that the modern rigidity of both plates decreases westward towards the Bay of Biscay. The lithospheric rigidity has increased by 50% since the Mesozoic with early Cenozoic EET values of 13 ± 2 and 8 ± 1 km for the European and Iberian plates, respectively. The topographic load began increasing with convergence in the late Cretaceous, reaching modern levels in the central and eastern Pyrenees by the Eocene. In contrast, the topographic load in the western Pyrenees was 70% of the modern value in the Eocene, and experienced topographic growth through the Oligo-Miocene. The

  1. A case report of radiation necrosis of the larynx

    International Nuclear Information System (INIS)

    Tanaka, Eiichi; Inouye, Tetsuzo; Hiraide, Fumihisa; Tsubaki, Yasukiyo; Miyakogawa, Norimasa; Sawada, Masamichi

    1983-01-01

    A case of radiation necrosis of the larynx is reported. The patient was a 79-year-old man who was radiated with the dosis of 3900 rad for suspected carcinoma of the larynx in 1976 and 5300 rad for carcinoma of the larynx in 1980. After completion of radiation therapy, he started to have hoarseness. He was admitted to the hospital because of severe dyspnea. Fiberoptic examination revealed almost complete obstruction of the laryngeal lumen by necrotic tissues due to radiation necrosis. There was little space reserved for respiration. No motility of the vocal cords and arytenoids was observed. After tracheostomy, conservative local and systemic treatments and repeated removal of necrotic tissues through laryngomicrosurgery were performed. However, an advanced necrosis with infection could not be controlled. Therefore, total laryngectomy was performed. Microscopically, no malignant cells were noted in the larynx. As most soft tissues were degenerated into fibrosis, the pharynx was left open. When infection was entirely controlled, the lining flap method from the anterior chest was applied to close the pharynx. When severe radiation necrosis occurs in the larynx, laryngectomy is sometimes mandatory to be performed. It is important that infection should be controlled before and after laryngectomy. Delayed skin flap method is advised. (author)

  2. Case report of radiation necrosis of the larynx

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Eiichi; Inouye, Tetsuzo; Hiraide, Fumihisa; Tsubaki, Yasukiyo; Miyakogawa, Norimasa; Sawada, Masamichi (National Defence Medical Coll., Tokorozawa, Saitama (Japan))

    1983-02-01

    A case of radiation necrosis of the larynx is reported. The patient was a 79-year-old man who was radiated with the dosis of 3900 rad for suspected carcinoma of the larynx in 1976 and 5300 rad for carcinoma of the larynx in 1980. After completion of radiation therapy, he started to have hoarseness. He was admitted to the hospital because of severe dyspnea. Fiberoptic examination revealed almost complete obstruction of the laryngeal lumen by necrotic tissues due to radiation necrosis. There was little space reserved for respiration. No motility of the vocal cords and arytenoids was observed. After tracheostomy, conservative local and systemic treatments and repeated removal of necrotic tissues through laryngomicrosurgery were performed. However, an advanced necrosis with infection could not be controlled. Therefore, total laryngectomy was performed. Microscopically, no malignant cells were noted in the larynx. As most soft tissues were degenerated into fibrosis, the pharynx was left open. When infection was entirely controlled, the lining flap method from the anterior chest was applied to close the pharynx. When severe radiation necrosis occurs in the larynx, laryngectomy is sometimes mandatory to be performed. It is important that infection should be controlled before and after laryngectomy. Delayed skin flap method is advised.

  3. Possible cause underlying gastric necrosis and perforation: Celiac artery thrombosis

    Directory of Open Access Journals (Sweden)

    Ahmet Peker

    2017-12-01

    Full Text Available In this article, we are sharing a case of a 76-year-old woman with known hypertension, atrial fibrillation,diabetes mellitus, coronary artery disease, who is presenting with stomach necrosis and perforation possibly due to celiac artery thrombosis after newly developed abdominal pain and bloody vomiting. In our case, emergency surgery was planned and the patient refused the operation and was lost at 48 hours of clinical follow-up. We aimed to discuss the etiology of celiac artery thrombosis, briefly. We believe that necrosis and perforation of the stomach due to celiac artery thrombosis deserves to be shared because it is a rare and difficult case to manage.

  4. Mastectomy skin necrosis after microsurgical breast reconstruction.

    Science.gov (United States)

    Vargas, Christina R; Koolen, Pieter G; Anderson, Katarina E; Paul, Marek A; Tobias, Adam M; Lin, Samuel J; Lee, Bernard T

    2015-10-01

    Mastectomy skin necrosis represents a significant clinical morbidity after immediate breast reconstruction. In addition to aesthetic deformity, necrosis of the native mastectomy skin may require debridement, additional reconstruction, or prolonged wound care and potentially delay oncologic treatment. This study aims to evaluate patient and procedural characteristics to identify predictors of mastectomy skin necrosis after microsurgical breast reconstruction. A retrospective review was performed of all immediate microsurgical breast reconstructions performed at a single academic center. Patient records were queried for age, diabetes, active smoking, previous breast surgery, preoperative radiation, preoperative chemotherapy, body mass index, mastectomy type, mastectomy weight, flap type, autologous flap type, and postoperative mastectomy skin flap necrosis. There were 746 immediate autologous microsurgical flaps performed by three plastic surgeons at our institution during the study period. The incidence of mastectomy skin flap necrosis was 13.4%. Univariate analysis revealed a significantly higher incidence of mastectomy skin necrosis in patients with higher mastectomy weight (P mastectomy type. Multivariate analysis demonstrated statistically significant associations between mastectomy skin necrosis and both increasing mastectomy weight (odds ratio 1.348 per quartile increase, P = 0.009) and diabetes (odds ratio 2.356, P = 0.011). Increasing mastectomy weight and coexisting diabetes are significantly associated with postoperative mastectomy skin necrosis after microsurgical reconstruction. These characteristics should be considered during patient counseling, procedure selection, operative planning, and intraoperative tissue viability assessment. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Comparative study of flexural strength test methods on CAD/CAM Y-TZP dental ceramics.

    Science.gov (United States)

    Xu, Yongxiang; Han, Jianmin; Lin, Hong; An, Linan

    2015-12-01

    Clinically, fractures are the main cause of computer-aided design and computer-aided manufacturing (CAD/CAM) 3 mol%-yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) all-ceramic dental restorations failure because of repetitive occlusal loading. The goal of this work is to study the effect of test methods and specimen's size on the flexural strength of five ceramic products. Both bi-axial flexure test (BI) and uni-axial flexure tests (UNI), including three-point flexure test (3PF) and four-point flexure test (4PF), are used in this study. For all five products, the flexural strength is as follows: BI > 3PF > 4PF. Furthermore, specimens with smaller size (3PF-s) have higher values than the bigger ones (3PF). The difference between BI and UNI resulted from the edge flaws in ceramic specimens. The relationship between different UNI (including 3PF-s, 3PF and 4PF) can be explained according to Weibull statistical fracture theory. BI is recommended to evaluate the flexural strength of CAD/CAM Y-TZP dental ceramics.

  6. Comparative study of flexural strength test methods on CAD/CAM Y-TZP dental ceramics

    Science.gov (United States)

    Xu, Yongxiang; Han, Jianmin; Lin, Hong; An, Linan

    2015-01-01

    Clinically, fractures are the main cause of computer-aided design and computer-aided manufacturing (CAD/CAM) 3 mol%-yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) all-ceramic dental restorations failure because of repetitive occlusal loading. The goal of this work is to study the effect of test methods and specimen’s size on the flexural strength of five ceramic products. Both bi-axial flexure test (BI) and uni-axial flexure tests (UNI), including three-point flexure test (3PF) and four-point flexure test (4PF), are used in this study. For all five products, the flexural strength is as follows: BI > 3PF > 4PF. Furthermore, specimens with smaller size (3PF-s) have higher values than the bigger ones (3PF). The difference between BI and UNI resulted from the edge flaws in ceramic specimens. The relationship between different UNI (including 3PF-s, 3PF and 4PF) can be explained according to Weibull statistical fracture theory. BI is recommended to evaluate the flexural strength of CAD/CAM Y-TZP dental ceramics. PMID:26816646

  7. Compressive strength, flexural strength and thermal conductivity of autoclaved concrete block made using bottom ash as cement replacement materials

    International Nuclear Information System (INIS)

    Wongkeo, Watcharapong; Thongsanitgarn, Pailyn; Pimraksa, Kedsarin; Chaipanich, Arnon

    2012-01-01

    Highlights: ► Autoclaved aerated concrete were produced using coal bottom ash as a cement replacement material. ► Coal bottom ash was found to enhance concrete strengths. ► Thermal conductivity of concrete was not significantly affected. ► X-ray diffraction and thermal analysis show tobermorite formation. -- Abstract: The bottom ash (BA) from Mae Moh power plant, Lampang, Thailand was used as Portland cement replacement to produce lightweight concrete (LWC) by autoclave aerated concrete method. Portland cement type 1, river sand, bottom ash, aluminium powder and calcium hydroxide (Ca(OH) 2 ) were used in this study. BA was used to replace Portland cement at 0%, 10%, 20% and 30% by weight and aluminium powder was added at 0.2% by weight in order to produce the aerated concrete. Compressive strength, flexural and thermal conductivity tests were then carried out after the concrete were autoclaved for 6 h and left in air for 7 days. The results show that the compressive strength, flexural strength and thermal conductivity increased with increased BA content due to tobermorite formation. However, approximately, 20% increase in both compressive (up to 11.61 MPa) and flexural strengths (up to 3.16 MPa) was found for mixes with 30% BA content in comparison to just around 6% increase in the thermal conductivity. Thermogravimetry analysis shows C–S–H formation and X-ray diffraction confirm tobermorite formation in bottom ash lightweight concrete. The use of BA as a cement replacement, therefore, can be seen to have the benefit in enhancing strength of the aerated concrete while achieving comparatively low thermal conductivity when compared to the results of the control Portland cement concrete.

  8. Regulation of Tumor Progression by Programmed Necrosis

    Directory of Open Access Journals (Sweden)

    Su Yeon Lee

    2018-01-01

    Full Text Available Rapidly growing malignant tumors frequently encounter hypoxia and nutrient (e.g., glucose deprivation, which occurs because of insufficient blood supply. This results in necrotic cell death in the core region of solid tumors. Necrotic cells release their cellular cytoplasmic contents into the extracellular space, such as high mobility group box 1 (HMGB1, which is a nonhistone nuclear protein, but acts as a proinflammatory and tumor-promoting cytokine when released by necrotic cells. These released molecules recruit immune and inflammatory cells, which exert tumor-promoting activity by inducing angiogenesis, proliferation, and invasion. Development of a necrotic core in cancer patients is also associated with poor prognosis. Conventionally, necrosis has been thought of as an unregulated process, unlike programmed cell death processes like apoptosis and autophagy. Recently, necrosis has been recognized as a programmed cell death, encompassing processes such as oncosis, necroptosis, and others. Metabolic stress-induced necrosis and its regulatory mechanisms have been poorly investigated until recently. Snail and Dlx-2, EMT-inducing transcription factors, are responsible for metabolic stress-induced necrosis in tumors. Snail and Dlx-2 contribute to tumor progression by promoting necrosis and inducing EMT and oncogenic metabolism. Oncogenic metabolism has been shown to play a role(s in initiating necrosis. Here, we discuss the molecular mechanisms underlying metabolic stress-induced programmed necrosis that promote tumor progression and aggressiveness.

  9. Determining the Compressive, Flexural and Splitting Tensile Strength of Silica Fume Reinforced Lightweight Foamed Concrete

    Directory of Open Access Journals (Sweden)

    Mydin M.A.O.

    2014-01-01

    Full Text Available This study investigated the performance of the properties of foamed concrete in replacing volumes of cement of 10%, 15% and 20% by weight. A control unit of foamed concrete mixture made with ordinary Portland cement (OPC and 10%, 15% and 20% silica fume was prepared. Three mechanical property parameters were studied such as compressive strength, flexural strength and splitting tensile of foamed concrete with different percentages of silica fume. Silica fume is commonly used to increase the mechanical properties of concrete materials and it is also chosen due to certain economic reasons. The foamed concrete used in this study was cured at a relative humidity of 70% and a temperature of ±28°C. The improvement of mechanical properties was due to a significant densification in the microstructure of the cement paste matrix in the presence of silica fume hybrid supplementary binder as observed from micrographs obtained in the study. The overall results showed that there is a potential to utilize silica fume in foamed concrete, as there was a noticeable enhancement of thermal and mechanical properties with the addition of silica fume.

  10. ROLE OF THE MITOCHONDRION IN PROGRAMMED NECROSIS

    Directory of Open Access Journals (Sweden)

    Christopher eBaines

    2010-11-01

    Full Text Available In contrast to the programmed nature of apoptosis and autophagy, necrotic cell death has always been believed to be a random, uncontrolled process that leads to the accidental death of the cell. This dogma, however, is being challenged and the concept of necrosis also being programmed is gaining ground. In particular, mitochondria appear to play a pivotal role in the mediation of programmed necrosis. The purpose of this review, therefore, is to appraise the current concepts regarding the signaling mechanisms of programmed necrosis, with specific attention to the contribution of mitochondria to this process.

  11. Acute Necrotizing Esophagitis Followed by Duodenal Necrosis

    Science.gov (United States)

    del Hierro, Piedad Magdalena

    2011-01-01

    Acute Necrotizing Esophagitis is an uncommon pathology, characterized by endoscopic finding of diffuse black coloration in esophageal mucosa and histological presence of necrosis in patients with upper gastrointestinal bleeding. The first case of acute necrotizing esophagitis followed by duodenal necrosis, in 81 years old woman with a positive history of Type 2 Diabetes Mellitus, Hypertension, and usual intake of Nonsteroidal Anti-inflammatory drugs, is reported. Although its etiology remains unknown, the duodenal necrosis suggests that ischemia could be the main cause given that the branches off the celiac axis provide common blood supply to the distal esophageal and duodenal tissue. The massive gastroesophagic reflux and NSAID intake could be involved. PMID:27957030

  12. Piroxicam induced submassive necrosis of the liver.

    Science.gov (United States)

    Paterson, D; Kerlin, P; Walker, N; Lynch, S; Strong, R

    1992-01-01

    Several widely used non-steroidal anti-inflammatory drugs have been reported as causing severe hepatitis. Three cases of severe acute hepatitis have been reported in association with piroxicam. A fatal submassive necrosis that occurred in a 68 year old lady who had received piroxicam for 15 months is described. A 48 year old man who developed submassive hepatic necrosis six weeks after beginning piroxicam but was successfully treated with orthotopic liver transplantation is also reported. Piroxicam may induce submassive necrosis of the liver, probably as an idiosyncratic reaction. Images Figure 1 Figure 2 Figure 3 PMID:1446877

  13. A colonic splenic flexure tumour presenting as an empyema thoracis: a case report.

    LENUS (Irish Health Repository)

    Murphy, K

    2009-01-01

    The case report describes the rare presentation of a 79-year-old patient with a locally perforated splenic flexure tumour of the colon presenting with an apparent empyema thoracis in the absence of abdominal signs or symptoms.

  14. Prediction on flexural strength of encased composite beam with cold-formed steel section

    Science.gov (United States)

    Khadavi, Tahir, M. M.

    2017-11-01

    A flexural strength of composite beam designed as boxed shaped section comprised of lipped C-channel of cold-formed steel (CFS) facing each other with reinforcement bars is proposed in this paper. The boxed shaped is kept restrained in position by a profiled metal decking installed on top of the beam to form a slab system. This profiled decking slab is cast by using self-compacting concrete where the concrete is in compression when load is applied to the beam. Reinforcement bars are used as shear connector between slab and CFS as beam. A numerical analysis method proposed by EC4 is used to predict the flexural strength of the proposed composite beam. It was assumed that elasto-plastic behaviour is developed in the cross -sectional of the proposed beam. The calculated predicted flexural strength of the proposed beam shows reasonable flexural strength for cold-formed composite beam.

  15. Study on Flexural Creep Parameters of Overlayed Particleboard by Natural and Melaminated Veneers

    Directory of Open Access Journals (Sweden)

    Abdollah Najafi

    2012-06-01

    Full Text Available In this study, effects of natural and artificial veneer on flexural creep behavior of particleboard was investigated. Particleboard panels were prepared from Pars Neopan industries with 660 kg/m3 density and then overlaid by natural and melamine veneers. Their creep behavior was compared to control particleboard. For evaluating maximum bending load in static flexural test, specimens were cut from panels according to ASTM D 1037 with dimensions of 370×50×16 mm. Then, The flexural creep tests at 20% and 40% of failure bending load was applied to test specimens. Results of flexural tests indicated that the MOR and MOE values of veneered particleboard were highest. Results of creep showed that levels of stresses are effective on all creep parameters, but showed less effect on relative creep. Also, creep parameters less effective on specimens overlaid by natural veneer.

  16. Flexural Strength of Acrylic Resin Denture Bases Processed by Two Different Methods

    Directory of Open Access Journals (Sweden)

    Jafar Gharechahi

    2014-09-01

    Full Text Available Background and aims. The aim of this study was to compare flexural strength of specimens processed by conventional and injection-molding techniques. Materials and methods. Conventional pressure-packed PMMA was used for conventional pressure-packed and injection-molded PMMA was used for injection-molding techniques. After processing, 15 specimens were stored in distilled water at room temperature until measured. Three-point flexural strength test was carried out. Statistical analysis was carried out by SPSS using t-test. Statistical significance was defined at P<0.05. Results. Flexural strength of injection-polymerized acrylic resin specimens was higher than that of theconventional method (P=0.006. This difference was statistically significant (P=0.006. Conclusion. Within the limitations of this study, flexural strength of acrylic resin specimens was influenced by the mold-ing technique.

  17. [Chronic recurrent volvulus of the colonic splenic flexure associated with the eventration of left diaphragm].

    Science.gov (United States)

    Kim, Hee Sun; Yoo, Jeong Seon; Han, Seok Joo; Park, Hyojin

    2007-01-01

    The eventration of diaphragm is usually found incidentally on chest X-ray or sometimes presented as acute gastric volvulus. However, colonic volvulus on splenic flexure area complicated by diaphragmatic eventration is extremely rare. A 25 year old man complained of upper abdominal pain for three days. He had a history of brain injury during infant period, and had epilepsy and mental retardation. Plain chest X-ray showed left diaphragmatic eventration and marked dilatation of colon on splenic flexure area which had not been changed for last three years. Barium enema showed bird beak appearance on distal colon near the splenic flexure. Colonoscopic reduction failed. After decompression with rectal and nasogastric tubes, colonic volvulus was relieved. To prevent the recurrence of volvulus, we performed segmental resection of left colon including splenic flexure area and repaired the left diaphragmatic eventration. After the operation, the patient had no further recurrent episode of volvulus although ileus persisted.

  18. Influence of Fretting on Flexural Fatigue of 304 Stainless Steel and Mild Steel

    National Research Council Canada - National Science Library

    Bill, Robert

    1978-01-01

    Fretting fatigue experiments conducted on 304 stainless steel using a flexural-fatigue test arrangement with bolted-on fretting pads have demonstrated that fatigue life is reduced by at least a factor...

  19. Perilesional edema in radiation necrosis reflects axonal degeneration

    International Nuclear Information System (INIS)

    Perez-Torres, Carlos J; Yuan, Liya; Schmidt, Robert E; Rich, Keith M; Ackerman, Joseph JH; Garbow, Joel R

    2015-01-01

    Recently, we characterized a Gamma Knife® radiation necrosis mouse model with various magnetic resonance imaging (MRI) protocols to identify biomarkers useful in differentiation from tumors. Though the irradiation was focal to one hemisphere, a contralateral injury was observed that appeared to be localized in the white matter only. Interestingly, this injury was identifiable in T2-weighted images, apparent diffusion coefficient (ADC), and magnetization transfer ratio (MTR) maps, but not on post-contrast T1-weighted images. This observation of edema independent of vascular changes is akin to the perilesional edema seen in clinical radiation necrosis. The pathology underlying the observed white-matter MRI changes was explored by performing immunohistochemistry for healthy axons and myelin. The presence of both healthy axons and myelin was reduced in the contralateral white-matter lesion. Based on our immunohistochemical findings, the contralateral white-matter injury is most likely due to axonal degeneration

  20. Flexural properties of laminated veneer lumber manufactured from ultrasonically rated red maple veneer : a pilot study.

    Science.gov (United States)

    Xiping Wang; Robert J. Ross; Brian K. Brashaw; Steven A. Verhey; John W. Forsman; John R. Erickson

    2003-01-01

    The study described in this report was conducted to examine the flexural properties of laminated veneer lumber (LVL) manufactured from red maple veneer. Ultrasonically rated veneer, which was peeled from low value red maple saw-logs, was fabricated into 1/2-in.-(1.3-cm-) and 2-in.-(5-cm-) thick LVL billets. The flexural properties of the billets and of corresponding...

  1. Modeling and analysis of circular flexural-vibration-mode piezoelectric transformer.

    Science.gov (United States)

    Huang, Yihua; Huang, Wei

    2010-12-01

    We propose a circular flexural-vibration-mode piezoelectric transformer and perform a theoretical analysis of the transformer. An equivalent circuit is derived from the equations of piezoelectricity and the Hamilton's principle. With this equivalent circuit, the voltage gain ratio, input impedance, and the efficiency of the circular flexural-vibration-mode piezoelectric transformer can be determined. The basic behavior of the transformer is shown by numerical results.

  2. An experimental study on flexural strength enhancement of concrete by means of small steel fibers

    Directory of Open Access Journals (Sweden)

    Abdoullah Namdar

    2013-10-01

    Full Text Available Cost effective improvement of the mechanical performances of structural materials is an important goal in construction industry. To improve the flexural strength of plain concrete so as to reduce construction costs, the addition of fibers to the concrete mixture can be adopted. The addition of small steel fibers with different lengths and proportion have experimentally been analyzed in terms of concrete flexural strength enhancement. The main objectives of the present study are related to the evaluation of the influence of steel fibers design on the increase of concrete flexural characteristics and on the mode of failure. Two types of beams have been investigated. The force level, deflection and time to failure of beams have been measured. The shear crack, flexural crack and intermediate shear-flexural crack have been studied. The steel fiber content controlled crack morphology. Flexural strength and time to failure of fiber reinforce concrete could be further enhanced if, instead of smooth steel fibers, corrugated fibers were used.

  3. Prediction of Mean and Design Fatigue Lives of Self Compacting Concrete Beams in Flexure

    Science.gov (United States)

    Goel, S.; Singh, S. P.; Singh, P.; Kaushik, S. K.

    2012-02-01

    In this paper, result of an investigation conducted to study the flexural fatigue characteristics of self compacting concrete (SCC) beams in flexure are presented. An experimental programme was planned in which approximately 60 SCC beam specimens of size 100 × 100 × 500 mm were tested under flexural fatigue loading. Approximately 45 static flexural tests were also conducted to facilitate fatigue testing. The flexural fatigue and static flexural strength tests were conducted on a 100 kN servo-controlled actuator. The fatigue life data thus obtained have been used to establish the probability distributions of fatigue life of SCC using two-parameter Weibull distribution. The parameters of the Weibull distribution have been obtained by different methods of analysis. Using the distribution parameters, the mean and design fatigue lives of SCC have been estimated and compared with Normally vibrated concrete (NVC), the data for which have been taken from literature. It has been observed that SCC exhibits higher mean and design fatigue lives compared to NVC.

  4. Flexural behavior of the fibrous cementitious composites (FCC) containing hybrid fibres

    Science.gov (United States)

    Ramli, Mahyuddin; Ban, Cheah Chee; Samsudin, Muhamad Fadli

    2018-02-01

    In this study, the flexural behavior of the fibrous cementitious composites containing hybrid fibers was investigated. Waste materials or by product materials such as pulverized fuel ash (PFA) and ground granulated blast-furnace slag (GGBS) was used as supplementary cement replacement. In addition, barchip and kenaf fiber will be used as additional materials for enhance the flexural behavior of cementitious composites. A seven mix design of fibrous cementitious composites containing hybrid fiber mortar were fabricated with PFA-GGBS as cement replacement at 50% with hybridization of barchip and kenaf fiber between 0.5% and 2.0% by total volume weight. The FCC with hybrid fibers mortar will be fabricated by using 50 × 50 × 50 mm, 40 × 40 × 160 mm and 350 × 125 × 30 mm steel mold for assessment of mechanical performances and flexural behavior characteristics. The flexural behavior and mechanical performance of the PFA-GGBS with hybrid fiber mortar block was assessed in terms of load deflection response, stress-strain response, crack development, compressive and flexural strength after water curing for 28 days. Moreover, the specimen HBK 1 and HBK 2 was observed equivalent or better in mechanical performance and flexural behavior as compared to control mortar.

  5. Compliance and control characteristics of an additive manufactured-flexure stage

    International Nuclear Information System (INIS)

    Lee, ChaBum; Tarbutton, Joshua A.

    2015-01-01

    This paper presents a compliance and positioning control characteristics of additive manufactured-nanopositioning system consisted of the flexure mechanism and voice coil motor (VCM). The double compound notch type flexure stage was designed to utilize the elastic deformation of two symmetrical four-bar mechanisms to provide a millimeter-level working range. Additive manufacturing (AM) process, stereolithography, was used to fabricate the flexure stage. The AM stage was inspected by using 3D X-ray computerized tomography scanner: air-voids and shape irregularity. The compliance, open-loop resonance peak, and damping ratio of the AM stage were measured 0.317 mm/N, 80 Hz, and 0.19, respectively. The AM stage was proportional-integral-derivative positioning feedback-controlled and the capacitive type sensor was used to measure the displacement. As a result, the AM flexure mechanism was successfully 25 nm positioning controlled within 500 μm range. The resonance peak was found approximately at 280 Hz in closed-loop. This research showed that the AM flexure mechanism and the VCM can provide millimeter range with high precision and can be a good alternative to an expensive metal-based flexure mechanism and piezoelectric transducer

  6. Compliance and control characteristics of an additive manufactured-flexure stage

    Energy Technology Data Exchange (ETDEWEB)

    Lee, ChaBum; Tarbutton, Joshua A. [Department of Mechanical Engineering, University of South Carolina, 300 Main St., Columbia, South Carolina 29208 (United States)

    2015-04-15

    This paper presents a compliance and positioning control characteristics of additive manufactured-nanopositioning system consisted of the flexure mechanism and voice coil motor (VCM). The double compound notch type flexure stage was designed to utilize the elastic deformation of two symmetrical four-bar mechanisms to provide a millimeter-level working range. Additive manufacturing (AM) process, stereolithography, was used to fabricate the flexure stage. The AM stage was inspected by using 3D X-ray computerized tomography scanner: air-voids and shape irregularity. The compliance, open-loop resonance peak, and damping ratio of the AM stage were measured 0.317 mm/N, 80 Hz, and 0.19, respectively. The AM stage was proportional-integral-derivative positioning feedback-controlled and the capacitive type sensor was used to measure the displacement. As a result, the AM flexure mechanism was successfully 25 nm positioning controlled within 500 μm range. The resonance peak was found approximately at 280 Hz in closed-loop. This research showed that the AM flexure mechanism and the VCM can provide millimeter range with high precision and can be a good alternative to an expensive metal-based flexure mechanism and piezoelectric transducer.

  7. Flexural behavior of bonded post-tensioned concrete beams under strand corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xuhui [College of Civil Engineering and Mechanics, Xiangtan University, 411105 Xiangtan (China); School of Civil Engineering and Architecture, Changsha University of Science & Technology, 410114 Changsha (China); Industry Key Laboratory of Traffic Infrastructure Security Risk Management (CSUST), 410114 Changsha (China); Wang, Lei, E-mail: leiwlei@hotmail.com [School of Civil Engineering and Architecture, Changsha University of Science & Technology, 410114 Changsha (China); Industry Key Laboratory of Traffic Infrastructure Security Risk Management (CSUST), 410114 Changsha (China); Zhang, Jianren; Ma, Yafei [School of Civil Engineering and Architecture, Changsha University of Science & Technology, 410114 Changsha (China); Industry Key Laboratory of Traffic Infrastructure Security Risk Management (CSUST), 410114 Changsha (China); Liu, Yongming [School for Engineering of Matter, Transport and Energy, Arizona State University, 85281 Tempe, AZ (United States)

    2017-03-15

    Highlights: • Flexural behavior of bonded PT beams with strand corrosion is experimental tested. • Cracking, stiffness, ultimate strength, failure & ductility of beams are clarified. • A coefficient is proposed to measure incompatible strain between strand & concrete. - Abstract: An experimental test is performed to investigate the flexural behavior of bonded post-tensioned concrete beams under strand corrosion. Eight beams are designed and subjected to accelerated method to different corrosion levels. The initial stiffness of beams is observed by cyclic loading-unloading test during the corrosion procedure. Corrosion effects on concrete cracking, post-cracking stiffness, ultimate strength, failure mode and ductility are then clarified by the flexural test. And, a coefficient is introduced to quantify the incompatible strain between corroded strand and concrete. Results show that the prestress force loss of strand has almost the linear relation with corrosion loss. Strand corrosion affects slightly the initial stiffness of beam before flexural cracking, but degrades significantly the post-cracking stiffness of beam as the corrosion loss exceeds 27.0%. Slight corrosion of strand has little effects on beams flexural behavior. The severe corrosion, however, decreases the number of crack, changes the failure mode form the concrete crushing to strand rupture, degrades the ductility and the ultimate strength of beams, and leads to the incompatible strain between strand and concrete. In the present test, the incompatible strain decreases about 20% of the flexural strength as the corrosion loss exceeds 27.0%.

  8. Laparoscopic resection of transverse colon cancer at splenic flexure: technical aspects and results.

    Science.gov (United States)

    Okuda, Junji; Yamamoto, Masashi; Tanaka, Keitaro; Masubuchi, Shinsuke; Uchiyama, Kazuhisa

    2016-03-01

    Laparoscopic resection of transverse colon cancer at splenic flexure is technical demanding and its efficacy remains controversial. The aim of this study was to investigate its technical aspects such as pitfalls and overcoming them, and to demonstrate the short-term and oncologic long-term outcomes. To overcome the difficulty in laparoscopic resection of transverse colon cancer at splenic flexure, we recognized the following technical tips as essential. First of all, we have to precisely identify major vessels variations feeding tumor. Secondary, anatomical dissection of mesocolon through medial approach is indispensible. Third, safe takedown of splenic flexure to fully mobilization of left hemicolon is mandatory. This cohort study analyzed 95 patients with stage II (43) and III (52) underwent resection of transverse colon cancer at splenic flexure. 61 laparoscopic surgeries (LAC) and 34 conventional open surgeries (OC) from December 1996 to December 2009 were evaluated. Short-term and oncologic long-term outcomes were recorded. Operative time was longer in LAC. However, blood loss was less, recovery of bowel function and hospital stay were shorter in LAC. There was no conversion in LAC and no significant difference in the postoperative complications. Regarding oncologic long-term outcomes, there were no significant differences between OC and LAC. Laparoscopic resection of transverse colon cancer at splenic flexure resulted in acceptable short-term and oncologic long-term outcomes. Once technical tips acquired, laparoscopic resection of transverse colon cancer at splenic flexure could be feasible as minimally invasive surgery.

  9. MODELLING AND FAILURE ANALYSIS OF FLEXURE SPRINGS FOR A STIRLING CRYOCOOLER

    Directory of Open Access Journals (Sweden)

    RAJESH V. R.

    2017-04-01

    Full Text Available In the range of milliwatt to a few watts cooling capacity, Stirling cycle and pulse tube coolers are most suitable for producing cryogenic temperatures owing to their eco-friendliness, high efficiency, cooling capacity to mass ratio etc. The compressor of a Stirling cooler is powered by a linear motor. The power piston of the cooler is held in position and moves to and fro with the support of so called flexure springs or flexure bearings. Flexures avoid direct contact between moving parts of the compressor of the cooler. Thus, if designed adequately to withstand fatigue, flexure bearings can easily outlast rolling element bearings and slider bearings. In this work, a computational analysis is used to study the performance of flexure spring by varying the geometrical parameters. Three of the most common spring materials namely, SS304, beryllium copper and spring steel are considered for analysis. The analysis was made by varying the parameters like spiral sweep angle, slot width, number of spirals and disc thickness. The influence of each of these parameters on the fatigue life of the spring has been investigated. The results suggest that flexure springs of three spiral arms would be the ideal choice for the selected cryocooler. The variation of stress developed with respect to different design parameters and fatigue damage factor are presented graphically.

  10. Flexural behavior of bonded post-tensioned concrete beams under strand corrosion

    International Nuclear Information System (INIS)

    Zhang, Xuhui; Wang, Lei; Zhang, Jianren; Ma, Yafei; Liu, Yongming

    2017-01-01

    Highlights: • Flexural behavior of bonded PT beams with strand corrosion is experimental tested. • Cracking, stiffness, ultimate strength, failure & ductility of beams are clarified. • A coefficient is proposed to measure incompatible strain between strand & concrete. - Abstract: An experimental test is performed to investigate the flexural behavior of bonded post-tensioned concrete beams under strand corrosion. Eight beams are designed and subjected to accelerated method to different corrosion levels. The initial stiffness of beams is observed by cyclic loading-unloading test during the corrosion procedure. Corrosion effects on concrete cracking, post-cracking stiffness, ultimate strength, failure mode and ductility are then clarified by the flexural test. And, a coefficient is introduced to quantify the incompatible strain between corroded strand and concrete. Results show that the prestress force loss of strand has almost the linear relation with corrosion loss. Strand corrosion affects slightly the initial stiffness of beam before flexural cracking, but degrades significantly the post-cracking stiffness of beam as the corrosion loss exceeds 27.0%. Slight corrosion of strand has little effects on beams flexural behavior. The severe corrosion, however, decreases the number of crack, changes the failure mode form the concrete crushing to strand rupture, degrades the ductility and the ultimate strength of beams, and leads to the incompatible strain between strand and concrete. In the present test, the incompatible strain decreases about 20% of the flexural strength as the corrosion loss exceeds 27.0%.

  11. Flexural properties of polyethylene, glass and carbon fiber-reinforced resin composites for prosthetic frameworks.

    Science.gov (United States)

    Maruo, Yukinori; Nishigawa, Goro; Irie, Masao; Yoshihara, Kumiko; Minagi, Shogo

    2015-01-01

    High flexural properties are needed for fixed partial denture or implant prosthesis to resist susceptibility to failures caused by occlusal overload. The aim of this investigation was to clarify the effects of four different kinds of fibers on the flexural properties of fiber-reinforced composites. Polyethylene fiber, glass fiber and two types of carbon fibers were used for reinforcement. Seven groups of specimens, 2 × 2 × 25 mm, were prepared (n = 10 per group). Four groups of resin composite specimens were reinforced with polyethylene, glass or one type of carbon fiber. The remaining three groups served as controls, with each group comprising one brand of resin composite without any fiber. After 24-h water storage in 37°C distilled water, the flexural properties of each specimen were examined with static three-point flexural test at a crosshead speed of 0.5 mm/min. Compared to the control without any fiber, glass and carbon fibers significantly increased the flexural strength (p glass fiber (p glass fibers (p > 0.05). Fibers could, therefore, improve the flexural properties of resin composite and carbon fibers in longitudinal form yielded the better effects for reinforcement.

  12. Effect of silver nano particles on flexural strength of acrylic resins.

    Science.gov (United States)

    Sodagar, Ahmad; Kassaee, Mohammad Zaman; Akhavan, Azam; Javadi, Negar; Arab, Sepideh; Kharazifard, Mohammad Javad

    2012-04-01

    Poly(methyl methacrylate), PMMA, is widely used for fabrication of removable orthodontic appliances. Silver nano particles (AgNps) have been added to PMMA because of their antimicrobial properties. The aim of this study is to investigate the effect of AgNps on the flexural strength of PMMA. Acrylic liquid containing 0.05% and 0.2% AgNps was prepared for two kinds of acrylic resins: Rapid Repair &Selecta Plus. Two groups without AgNps were used as control groups. For each one, flexural strength was investigated via Three Point Bending method for the 15 acrylic blocks. Two-way ANOVA, one way ANOVA and Tukey tests were used for statistical analysis. Rapid Repair without AgNps showed the highest flexural strength. Addition of 0.05% AgNps to Rapid Repair, significantly decreased its flexural strength while, continuing the addition up to 0.2% increased it nearly up to its primary level. In contrast, addition of AgNps to Selecta Plus increased its flexural strength but addition of 0.05% nano particles was more effective than 0.2%. The effect of AgNps on flexural strength of PMMA depends on several factors including the type of acrylics and the concentrations of nano particles. Copyright © 2011 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  13. Intracellular serpins, firewalls and tissue necrosis.

    Science.gov (United States)

    Marciniak, Stefan J; Lomas, David A

    2008-02-01

    Luke and colleagues have recently attributed a new role to a member of the serpin superfamily of serine proteinase inhibitors. They have used Caenorhabditis elegans to show that an intracellular serpin is crucial for maintaining lysosomal integrity. We examine the role of this firewall in preventing necrosis and attempt to integrate this with current theories of stress-induced protein degradation. We discuss how mutant serpins cause disease either through polymerization or now, perhaps, by unleashing necrosis.

  14. Imaging Tumor Necrosis with Ferumoxytol.

    Directory of Open Access Journals (Sweden)

    Maryam Aghighi

    high T1 signal in areas of tumor necrosis and low signal in areas of intracellularly compartmentalized iron.Differential T1- and T2-enhancement patterns of USPIO in tumors enable conclusions about their intracellular and extracellular location. This information can be used to characterize the composition of the tumor microenvironment.

  15. Tumour Necrosis Factor-alpha and Nuclear Factor-kappa B Gene Variants in Sepsis.

    Science.gov (United States)

    Acar, Leyla; Atalan, Nazan; Karagedik, E Hande; Ergen, Arzu

    2018-01-20

    The humoral system is activated and various cytokines are released due to infections in tissues and traumatic damage. Nuclear factor-kappa B dimers are encoded by nuclear factor-kappa B genes and regulate transcription of several crucial proteins of inflammation such as tumour necrosis factor-alpha. To investigate the possible effect of polymorphisms on tumour necrosis factor-alpha serum levels with clinical and prognostic parameters of sepsis by determining the nuclear factor-kappa B-1-94 ins/del ATTG and tumour necrosis factor-alpha (-308 G/A) gene polymorphisms and tumour necrosis factor-alpha serum levels. Case-control study. Seventy-two patients with sepsis and 104 healthy controls were included in the study. In order to determine the polymorphisms of nuclear factor-kappa B-1-94 ins/del ATTG and tumour necrosis factor-alpha (-308 G/A), polymerase chain reaction-restriction fragment length polymorphism analysis was performed and serum tumour necrosis factor-alpha levels were determined using an enzyme-linked immunosorbent assay. We observed no significant differences in tumour necrosis factor-alpha serum levels between the study groups. In the patient group, an increase in the tumour necrosis factor-alpha serum levels in patients carrying the tumour necrosis factor-alpha (-308 G/A) A allele compared to those without the A allele was found to be statistically significant. Additionally, an increase in the tumour necrosis factor-alpha serum levels in patients carrying tumour necrosis factor-alpha (-308 G/A) AA genotype compared with patients carrying the AG or GG genotypes was statistically significant. No significant differences were found in these 2 polymorphisms between the patient and control groups (p>0.05). Our results showed the AA genotype and the A allele of the tumour necrosis factor-alpha (-308 G/A) polymorphism may be used as a predictor of elevated tumour necrosis factor-alpha levels in patients with sepsis.

  16. Bioresorbable composite screws manufactured via forging process: pull-out, shear, flexural and degradation characteristics.

    Science.gov (United States)

    Felfel, R M; Ahmed, I; Parsons, A J; Rudd, C D

    2013-02-01

    Bioresorbable screws have the potential to overcome some of the complications associated with metallic screws currently in use. Removal of metallic screws after bone has healed is a serious issue which can lead to refracture due to the presence of screw holes. Poly lactic acid (PLA), fully 40 mol% P(2)O(5) containing phosphate unidirectional (P40UD) and a mixture of UD and short chopped strand random fibre mats (P40 70%UD/30%RM) composite screws were prepared via forging composite bars. Water uptake and mass loss for the composite screws manufactured increased significantly to ∼1.25% (P=0.0002) and ∼1.1% (P<0.0001), respectively, after 42 days of immersion in PBS at 37 °C. The initial maximum flexural load for P40 UD/RM and P40 UD composite screws was ∼60% (P=0.0047) and ∼100% (P=0.0037) higher than for the PLA screws (∼190 N), whilst the shear load was slightly higher in comparison to PLA (∼2.2 kN). The initial pull-out strengths for the P40 UD/RM and PLA screws were similar whereas that for P40 UD screws was ∼75% higher (P=0.022). Mechanical properties for the composite screws decreased initially after 3 days of immersion and this reduction was ascribed to the degradation of the fibre/matrix interface. After 3 days interval the mechanical properties (flexural, shear and pull-out) maintained their integrity for the duration of the study (at 42 days). This property retention was attributed to the chemical durability of the fibres used and stability of the matrix properties during the degradation process. It was also deemed necessary to enhance the fibre/matrix interface via use of a coupling agent in order to maintain the initial mechanical properties acquired for the required period of time. Lastly, it is also suggested that the degrading reinforcement fibres may have the potential to buffer any acidic products released from the PLA matrix. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Flexure mechanism-based parallelism measurements for chip-on-glass bonding

    International Nuclear Information System (INIS)

    Jung, Seung Won; Yun, Won Soo; Jin, Songwan; Jeong, Young Hun; Kim, Bo Sun

    2011-01-01

    Recently, liquid crystal displays (LCDs) have played vital roles in a variety of electronic devices such as televisions, cellular phones, and desktop/laptop monitors because of their enhanced volume, performance, and functionality. However, there is still a need for thinner LCD panels due to the trend of miniaturization in electronic applications. Thus, chip-on-glass (COG) bonding has become one of the most important aspects in the LCD panel manufacturing process. In this study, a novel sensor was developed to measure the parallelism between the tooltip planes of the bonding head and the backup of the COG main bonder, which has previously been estimated by prescale pressure films in industry. The sensor developed in this study is based on a flexure mechanism, and it can measure the total pressing force and the inclination angles in two directions that satisfy the quantitative definition of parallelism. To improve the measurement accuracy, the sensor was calibrated based on the estimation of the total pressing force and the inclination angles using the least-squares method. To verify the accuracy of the sensor, the estimation results for parallelism were compared with those from prescale pressure film measurements. In addition, the influence of parallelism on the bonding quality was experimentally demonstrated. The sensor was successfully applied to the measurement of parallelism in the COG-bonding process with an accuracy of more than three times that of the conventional method using prescale pressure films

  18. Failure Predictions of Out-of-Autoclave Sandwich Joints with Delaminations Under Flexure Loads

    Science.gov (United States)

    Nordendale, Nikolas A.; Goyal, Vinay K.; Lundgren, Eric C.; Patel, Dhruv N.; Farrokh, Babak; Jones, Justin; Fischetti, Grace; Segal, Kenneth N.

    2015-01-01

    An analysis and a test program was conducted to investigate the damage tolerance of composite sandwich joints. The joints contained a single circular delamination between the face-sheet and the doubler. The coupons were fabricated through out-of-autoclave (OOA) processes, a technology NASA is investigating for joining large composite sections. The four-point bend flexure test was used to induce compression loading into the side of the joint where the delamination was placed. The compression side was chosen since it tends to be one of the most critical loads in launch vehicles. Autoclave cure was used to manufacture the composite sandwich sections, while the doubler was co-bonded onto the sandwich face-sheet using an OOA process after sandwich panels were cured. A building block approach was adopted to characterize the mechanical properties of the joint material, including the fracture toughness between the doubler and face-sheet. Twelve four-point-bend samples were tested, six in the sandwich core ribbon orientation and six in sandwich core cross-ribbon direction. Analysis predicted failure initiation and propagation at the pre-delaminated location, consistent with experimental observations. A building block approach using fracture analyses methods predicted failure loads in close agreement with tests. This investigation demonstrated a small strength reduction due to a flaw of significant size compared to the width of the sample. Therefore, concerns of bonding an OOA material to an in-autoclave material was mitigated for the geometries, materials, and load configurations considered.

  19. Experimental Study On Flexural Behaviour Of Beams Reinforced With GFRP Rebars

    Science.gov (United States)

    Naveen Kumar, G.; Sundaravadivelu, Karthik

    2017-07-01

    In saline, moisture and cold conditions corrosion of steel is inevitable and the lot of economy is used for rehabilitation works. Corrosion of steel is nothing but oxidation of iron in moisture conditions and this corrosion leads to the spalling of concrete which intern reduces the strength of the structure. To reduce this corrosion effects, new materials with resistance against corrosion have to be introduced. Many experiments are going on using Glass Fiber Reinforced Polymer (GFRP) as alternate material for steel due to its non-corrosive nature, weight of GFRP is nearly one third of steel and ultimate tensile strength is higher than steel. In this paper, six beams are casted in which three beams are casted with steel as main and shear reinforcement and another three beams are casted with GFRP as main reinforcement with steel as shear reinforcing material. All beams casted are of same dimensions with variation in reinforcement percentage. The size of the beams casted is of length 1200 mm, breadth 100 mm and depth 200 mm. The clear cover of 25 mm is provided on top and bottom of the beam. Beams are tested under two-point loading with constant aspect ratio (a/d) and comparing the flexural strength, load deflection curves and types of failures of beams reinforced with GFRP as main reinforcement and beams reinforced with conventional steel. The final experimental results are compared with numerical results. M30 grade concrete with Conplast as a superplasticizer is used for casting beams.

  20. Flexural Behaviour of Reinforced Fibrous Concrete Beams: Experiments and Analytical Modelling

    International Nuclear Information System (INIS)

    Hameed, R.; Sellier, A.; Turatsinze, A.; Duprat, F.

    2013-01-01

    Flexural behaviour of reinforced fibrous concrete beams was investigated in this research study. Two types of metallic fibers were studied: amorphous metallic fibers (FibraFlex fibers), and carbon steel hooked-end fibers (Dramix fibers). Four types of reinforced concretes were made: one control (without fibers) and three fibrous. Among three reinforced fibrous concretes, two contained fibers in mono form and one contained fibers in hybrid form. The total quantity of fibers in mono and hybrid forms was 20 kg/m3 and 40 kg/m3, respectively. Three point bending tests were performed according to European standards NF EN 14651 on beams of 150 x 150 mm cross section and length of 550 mm. The results showed that due to positive synergetic interaction between the two metallic fibers used, reinforced fibrous concret (RFC) beams containing fibers in hybrid form exhibited better response at all loading stages. Analytical model to predict ultimate moment capacity of the RFC beam of rectangular section was developed and is presented in this paper. Analytical results for ultimate moment were found to be in good agreement with experimental results. (author)

  1. Flexural and diametral tensile strength of composite resins

    Directory of Open Access Journals (Sweden)

    Álvaro Della Bona

    2008-03-01

    Full Text Available This study evaluated the flexural strength (sf and the diametral tensile strength (st of light-cured composite resins, testing the hypothesis that there is a positive relation between these properties. Twenty specimens were fabricated for each material (Filtek Z250- 3M-Espe; AM- Amelogen, Ultradent; VE- Vit-l-escence, Ultradent; EX- Esthet-X, Dentsply/Caulk, following ISO 4049 and ANSI/ADA 27 specifications and the manufacturers’ instructions. For the st test, cylindrical shaped (4 mm x 6 mm specimens (n = 10 were placed with their long axes perpendicular to the applied compressive load at a crosshead speed of 1.0 mm/min. The sf was measured using the 3-point bending test, in which bar shaped specimens (n = 10 were tested at a crosshead speed of 0.5 mm/min. Both tests were performed in a universal testing machine (EMIC 2000 recording the fracture load (N. Strength values (MPa were calculated and statistically analyzed by ANOVA and Tukey (a = 0.05. The mean and standard deviation values (MPa were Z250-45.06 ± 5.7; AM-35.61 ± 5.4; VE-34.45 ± 7.8; and EX-42.87 ± 6.6 for st; and Z250-126.52 ± 3.3; AM-87.75 ± 3.8; VE-104.66 ± 4.4; and EX-119.48 ± 2.1 for sf. EX and Z250 showed higher st and sf values than the other materials evaluated (p < 0.05, which followed a decreasing trend of mean values. The results confirmed the study hypothesis, showing a positive relation between the material properties examined.

  2. Colonic Necrosis in a 4-Year-Old with Hyperlipidemic Acute Pancreatitis

    Directory of Open Access Journals (Sweden)

    Tiffany J. Patton

    2016-01-01

    Full Text Available Here we report the case of a 4-year-old male with severe acute pancreatitis due to hyperlipidemia, who presented with abdominal pain, metabolic abnormalities, and colonic necrosis. This colonic complication was secondary to the extension of a large peripancreatic fluid collection causing direct serosal autodigestion by pancreatic enzymes. Two weeks following the initial presentation, the peripancreatic fluid collection developed into a mature pancreatic pseudocyst, which was percutaneously drained. To our knowledge, this is the youngest documented pediatric case of colonic necrosis due to severe pancreatitis and the first descriptive pediatric case of a colonic complication due to hyperlipidemia-induced acute pancreatitis.

  3. Flexural Strength of Banana Fibre Reinforced Epoxy Composites Produced through Vacuum Infusion and Hand Lay-Up Techniques - A Comparative Study

    Directory of Open Access Journals (Sweden)

    Mohamed Rahman

    2017-07-01

    Full Text Available Natural fiber such as kenaf, sisal, pineapple leaf and banana are growing popular nowadays due to its favor over traditional glass fiber and inorganic material. It is a renewable resources and abundantly available in the market. The composites made of natural fiber are economical, lightweight and environmental friendly. This study works on producing a composite based on the Banana fiber reinforced epoxy resin by using the method of Vacuum Infusion and Hand Lay-up. Banana fiber will be treated with Sodium Hydroxide (NaOH and water solution for 1 hour and then dried in the oven for 24 hours at 100°C. The composite will be produce based on different fiber volume fraction of 20% and 40% as well as different fiber length of 127mm, and 63mm. In Vacuum Infusion process, a mold made of aluminium have been manufactured according to the size of specimens of 127mm x 12.7mm x 3.2mm in dimension will be used in the preparation of specimens. The specimens of different volume fraction and fiber length produced by vacuum infusion and hand lay-up method will be mechanically tested through flexural test. The highest flexural strength is the specimen made by vacuum infusion process with 40% volume fraction and 63mm fiber length, which is 136.27MPa while for the hand lay-up process, the highest flexural strength is 80.71 with 40% volume fraction and 63mm fiber length.

  4. Bilateral acute retinal necrosis after herpetic meningitis

    Directory of Open Access Journals (Sweden)

    Katsura T

    2012-04-01

    Full Text Available Keisho Hirota1,2, Masayuki Akimoto1,3, Toshiaki Katsura21Department of Ophthalmology, Kyoto Medical Center, National Hospital Organization, 2Internal Medicine, Kyoto Medical Center, 3Clinical Research Center, Kyoto Medical Center, Kyoto, JapanPurpose: The report of a case of bilateral acute retinal necrosis after herpetic meningitis.Case report: A 47-year-old man was admitted with the chief complaint of persistent high fever and transient loss of consciousness. Although his general condition improved after intravenous acyclovir administration, the patient presented with visual loss in both eyes 4 days after admission. Visual acuity in his right eye was 20/200 and his left eye had light perception alone. Both eyes showed panretinal arteritis diagnosed as acute retinal necrosis. Panretinal photocoagulation was performed for both eyes. Progression of retinal detachment was prevented in both eyes; however, visual acuity of the left eye was totally lost because of neovascular glaucoma. Visual acuity of the right eye recovered to 20/20.Conclusion: Although cases of bilateral acute retinal necrosis have been reported after herpetic encephalitis, this condition is rare after herpetic meningitis. Prophylactic acyclovir therapy and early panretinal photocoagulation may prevent retinal detachment and improve the prognosis. Neurologists and ophthalmologists should be aware that not only herpetic encephalitis but also herpetic meningitis can lead to acute retinal necrosis within a very short interval.Keywords: acute retinal necrosis, herpetic meningitis, herpes simplex, varicella zoster virus

  5. Flexural behaviour and punching shear of selfcompacting concrete ribbed slab reinforced with steel fibres

    Directory of Open Access Journals (Sweden)

    Ahmad Hazrina

    2017-01-01

    Full Text Available This paper investigates the effects of steel fibres as a replacement to the conventional reinforcement under flexural behaviour and punching shear in self-compacting (SCC ribbed slab reinforced with steel fibres. Four ribbed slabs with similar dimensions of 2.8 m length × 1.2 m width and 0.2m thickness were constructed. Two of the samples were considered as control samples (conventionally reinforced with reinforcement bars and welded mesh while another two samples were fully reinforced with 1% (80 kg/m3 volume of steel fibres incorporated to the SCC mix. For the flexural behaviour study, the ribbed slab samples were subjected to two line loads under four point bending. Meanwhile, for the punching shear analysis, the ribbed slab samples were subjected to a point load to simulate loading from the column. The analysis of the experimental results displayed that steel fibres incorporation had been found to effectively delay the first crack occurrence under both flexural and punching shear. The steel fibre replacement has been proven to be able to sustain up to 80% and 73% of the ultimate load resistance for flexural and punching shear, respectively, in comparison to conventionally reinforced ribbed slab structure. The visual observation carried out during the experiment exhibited similar failure mode for both steel fibre reinforced and control samples. This was observed for both flexural and punching shear samples. Overall, it can be concluded that the steel fibres had displayed a promising potential to effectively replace the conventional reinforcements.

  6. Lateral variations in foreland flexure of a rifted continental margin: The Aquitaine Basin (SW France)

    Science.gov (United States)

    Angrand, P.; Ford, M.; Watts, A. B.

    2017-12-01

    We study the effects of the inherited Aptian to Cenomanian rift on crustal rheology and evolution of the Late Cretaceous to Neogene flexural Aquitaine foreland basin, northern Pyrenees. We use surface and subsurface geological data to define the crustal geometry and the post-rift thermal subsidence, and Bouguer gravity anomalies and flexural modeling to study the lateral variation of the elastic thickness, flexure of the European plate and controlling loads. The Aquitaine foreland can be divided along-strike into three sectors. The eastern foreland is un-rifted and is associated with a simple flexural subsidence. The central sector is affected by crustal stretching and the observed foreland base is modeled by combining topographic and buried loads, with post-rift thermal subsidence. In the western sector the foreland basin geometry is mainly controlled by post-rift thermal subsidence. These three sectors are separated by major lineaments, which affect both crustal and foreland geometry. These lineaments seem to be part of a larger structural pattern that includes the Toulouse and Pamplona Faults. The European foreland shows lateral variations in flexural behavior: the relative role of surface and sub-surface (i.e., buried) loading varies along-strike and the elastic thickness values decrease from the north-east to the south-west where the plate is the most stretched. We suggest that foreland basins are influenced by the thermal state of the underlying lithosphere if it was initiated soon after rifting and that thermal cooling can contribute significantly to subsidence.

  7. Behaviour of glued fibre composite sandwich structure in flexure: Experiment and Fibre Model Analysis

    International Nuclear Information System (INIS)

    Manalo, Allan; Aravinthan, Thiru

    2012-01-01

    Highlights: ► Fibre Model Analysis is used to examine the flexural behaviour of sandwich beams. ► Theoretical prediction using FMA is in good agreement with the experiment. ► Using the constituent materials in FMA predicted accurately the beam’s behaviour. ► FMA can be used for analysing sandwich beams with high-strength core in flexure. -- Abstract: The behaviour of glued composite sandwich beams in flexure was investigated with a view of using this material for structural and civil engineering applications. The building block of this glue-laminated beam is a new generation composite sandwich structure made up of glass fibre reinforced polymer skins and a high strength phenolic core material. A simplified Fibre Model Analysis (FMA) usually used to analyse a concrete beam section is adopted to theoretically describe the flexural behaviour of the innovative sandwich beam structure. The analysis included the flexural behaviour of the glued sandwich beams in the flatwise and the edgewise positions. The FMA accounted for the non-linear behaviour of the phenolic core in compression, the cracking of the core in tension and the linear elastic behaviour of the fibre composite skin. The results of the FMA showed a good agreement with the experimental data showing the efficiency and practical applications of the simplified FMA in analysing and designing sandwich structures with high strength core material.

  8. Investigation on the flexural behaviour of reinforced concrete beams using phyllite aggregates from mining waste

    International Nuclear Information System (INIS)

    Adom-Asamoah, Mark; Afrifa, Russell Owusu

    2011-01-01

    Highlights: → Most parts of the world's geology is underlain by phyllite rocks. → Crack widths not well predicted so may not be used in water retaining structures. → Shear failure mode and low displacement ductility often observed in beams. → Concrete shear capacity observed lower than code values. -- Abstract: This paper investigated the flexural behaviour of 12 reinforced concrete (RC) beams made of phyllite coarse aggregates produced as by-product of underground gold mining activity. The beams were tested to failure under four point test. Collapse of the beams which were adequately designed against shear failure occurred mostly through either flexural-shear failure and/or diagonal tension failure. The experimental failure loads averaged approximately 115% of the theoretical failure loads. It was observed that the beams developed early shear cracks and higher flexural crack widths than allowable at service loads. Deflections compared reasonably well with the design code requirement but displacement ductility was low. It is recommended that British Standard (BS) 8110 design concrete shear stress values be multiplied by 0.8 to assure that the predicted shear capacity of phyllite concrete would be low and reasonable as compared to flexural capacity. In that case, BS 8110 can be used to provide adequate load factor against flexural failure for under-reinforced RC beams made of phyllite coarse aggregates.

  9. Evaluation of cyclic flexural fatigue of M-wire nickel-titanium rotary instruments.

    Science.gov (United States)

    Al-Hadlaq, Solaiman M S; Aljarbou, Fahad A; AlThumairy, Riyadh I

    2010-02-01

    This study was conducted to investigate cyclic flexural fatigue resistance of GT series X rotary files made from the newly developed M-wire nickel-titanium alloy compared with GT and Profile nickel-titanium files made from a conventional nickel-titanium alloy. Fifteen files, size 30/0.04, of each type were used to evaluate the cyclic flexural fatigue resistance. A simple device was specifically constructed to measure the time each file type required to fail under cyclic flexural fatigue testing. The results of this experiment indicated that the GT series X files had superior cyclic flexural fatigue resistance than the other 2 file types made from a conventional nickel-titanium alloy (P = .004). On the other hand, the difference between the Profile and the GT files was not statistically significant. The findings of this study suggest that size 30/0.04 nickel-titanium rotary files made from the newly developed M-wire alloy have better cyclic flexural fatigue resistance than files of similar design and size made from the conventional nickel-titanium alloy. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  10. Robust fiber optic flexure sensor exploiting mode coupling in few-mode fiber

    Science.gov (United States)

    Nelsen, Bryan; Rudek, Florian; Taudt, Christopher; Baselt, Tobias; Hartmann, Peter

    2015-05-01

    Few-mode fiber (FMF) has become very popular for use in multiplexing telecommunications data over fiber optics. The simplicity of producing FMF and the relative robustness of the optical modes, coupled with the simplicity of reading out the information make this fiber a natural choice for communications. However, little work has been done to take advantage of this type of fiber for sensors. Here, we demonstrate the feasibility of using FMF properties as a mechanism for detecting flexure by exploiting mode coupling between modes when the cylindrical symmetry of the fiber is perturbed. The theoretical calculations shown here are used to understand the coupling between the lowest order linearly polarized mode (LP01) and the next higher mode (LP11x or LP11y) under the action of bending. Twisting is also evaluated as a means to detect flexure and was determined to be the most reliable and effective method when observing the LP21 mode. Experimental results of twisted fiber and observations of the LP21 mode are presented here. These types of fiber flexure sensors are practical in high voltage, high magnetic field, or high temperature medical or industrial environments where typical electronic flexure sensors would normally fail. Other types of flexure measurement systems that utilize fiber, such as Rayleigh back-scattering [1], are complicated and expensive and often provide a higher-than necessary sensitivity for the task at hand.

  11. Elastic thickness determination based on Vening Meinesz-Moritz and flexural theories of isostasy

    Science.gov (United States)

    Eshagh, Mehdi

    2018-06-01

    Elastic thickness (Te) is one of mechanical properties of the Earth's lithosphere. The lithosphere is assumed to be a thin elastic shell, which is bended under the topographic, bathymetric and sediment loads on. The flexure of this elastic shell depends on its thickness or Te. Those shells having larger Te flex less. In this paper, a forward computational method is presented based on the Vening Meinesz-Moritz (VMM) and flexural theories of isostasy. Two Moho flexure models are determined using these theories, considering effects of surface and subsurface loads. Different values are selected for Te in the flexural method to see by which one, the closest Moho flexure to that of the VMM is achieved. The effects of topographic/bathymetric, sediments and crustal crystalline masses, and laterally variable upper mantle density, Young's modulus and Poisson's ratio are considered in whole computational process. Our mathematical derivations are based on spherical harmonics, which can be used to estimate Te at any single point, meaning that there is no edge effect in the method. However, the Te map needs to be filtered to remove noise at some points. A median filter with a window size of 5° × 5° and overlap of 4° works well for this purpose. The method is applied to estimate Te over South America using the data of CRUST1.0 and a global gravity model.

  12. Characterization of mechanical properties of pericardium tissue using planar biaxial tension and flexural deformation.

    Science.gov (United States)

    Murdock, Kyle; Martin, Caitlin; Sun, Wei

    2018-01-01

    Flexure is an important mode of deformation for native and bioprosthetic heart valves. However, mechanical characterization of bioprosthetic leaflet materials has been done primarily through planar tensile testing. In this study, an integrated experimental and computational cantilever beam bending test was performed to characterize the flexural properties of glutaraldehyde-treated bovine and porcine pericardium of different thicknesses. A strain-invariant based structural constitutive model was used to model the pericardial mechanical behavior quantified through the bending tests of this study and the planar biaxial tests previously performed. The model parameters were optimized through an inverse finite element (FE) procedure in order to describe both sets of experimental data. The optimized material properties were implemented in FE simulations of transcatheter aortic valve (TAV) deformation. It was observed that porcine pericardium TAV leaflets experienced significantly more flexure than bovine when subjected to opening pressurization, and that the flexure may be overestimated using a constitutive model derived from purely planar tensile experimental data. Thus, modeling of a combination of flexural and biaxial tensile testing data may be necessary to more accurately describe the mechanical properties of pericardium, and to computationally investigate bioprosthetic leaflet function and design. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Geometric controls of the flexural gravity waves on the Ross Ice Shelf

    Science.gov (United States)

    Sergienko, O. V.

    2017-12-01

    Long-period ocean waves, formed locally or at distant sources, can reach sub-ice-shelf cavities and excite coupled motion in the cavity and the ice shelf - flexural gravity waves. Three-dimensional numerical simulations of the flexural gravity waves on the Ross Ice Shelf show that propagation of these waves is strongly controlled by the geometry of the system - the cavity shape, its water-column thickness and the ice-shelf thickness. The results of numerical simulations demonstrate that propagation of the waves is spatially organized in beams, whose orientation is determined by the direction of the of the open ocean waves incident on the ice-shelf front. As a result, depending on the beams orientation, parts of the Ross Ice Shelf experience significantly larger flexural stresses compared to other parts where the flexural gravity beams do not propagate. Very long-period waves can propagate farther away from the ice-shelf front exciting flexural stresses in the vicinity of the grounding line.

  14. Subcutaneous fat necrosis of the newborn.

    Science.gov (United States)

    Oswalt, G C; Montes, L F; Cassady, G

    1978-08-01

    Subcutaneous fat necrosis of the newborn (SFNN) developed in a 1-week-old black boy. His mother had received numerous medications for eclampsia. Birth was by Caesarean section and complicated by meconium aspiration. There were numerous nodules over the back, buttocks and extremities that yielded a caseous-like material. Microscopically, these nodules showed crystallization and necrosis of the fat. Hypoglycemia, pneumonia, oliguria, thrombocytopenia, seizures and urinary infection were associated with the cutaneous problem and led to a fatal outcome 2 weeks after birth.

  15. Breast necrosis associated with thromboembolic disorders

    International Nuclear Information System (INIS)

    Andersson, I.; Adler, D.D.; Ljungberg, O.; Malmoe Allmaenna Sjukhus; Michigan Univ., Ann Arbor

    1987-01-01

    Two obese women with thrombotic disease complicated by necrosis of the breast are described. In one patient the reaction started after a few days of coumarin treatment and progressed to severe necrosis requiring mastectomy. The other patient was not on anticoagulant therapy when the breast reaction started and the clinical course was less severe. The radiographic appearance was characterized by thickening of the breast trabeculae, increased density of the breast and skin thickening. Although the radiographic findings are non-specific, the correct diagnosis can be suggested if combined with appropriate clinical information. The disease process may mimic breast cancer of the inflammatory type, clinically as well as radiographically. (orig.)

  16. ICESat-derived lithospheric flexure as caused by an endorheic lake's expansion on the Tibetan Plateau and the comparison to modeled flexural responses

    Science.gov (United States)

    Madson, Austin; Sheng, Yongwei; Song, Chunqiao

    2017-10-01

    A substantial and rapid expansion beginning in the late 1990s of Siling Co, the largest endorheic lake on the central Tibetan Plateau (TP), has caused a measurable lithospheric deflection in the region adjacent to the lake. Current broad-scale measuring of this flexural response is mainly derived from InSAR processing techniques or time-consuming field campaigns. The rheological constraints of the lithosphere from the underlying lithospheric response to large lake loads in this region are not well understood. This paper highlights a more efficient spaceborne LiDAR remote sensing technique to measure the deflection in the vicinity of Siling Co and to investigate the mechanisms of the observed lithospheric response in order to garner a better understanding of the local rheology. A lake-adjacent deflection rate and Siling Co water load variations are calculated utilizing the Geoscience Laser Altimeter System (GLAS) onboard NASA's Ice, Cloud and land Elevation Satellite (ICESat) and the joint NASA/USGS Landsat series of Earth observing satellites. A downward deflection rate of ∼5.6 mm/yr for the first 4 km of lake-adjacent land is calculated from the GLAS instrument, and this response is compared to the flexural outputs from a spherically symmetric, non-rotating, elastic, and isotropic (SNREI) Earth model in order to better understand the underlying mechanisms of the lithospheric response to the rapid increase of Siling Co loads. The modeled elastic response is ∼6.9 times lower than the GLAS derived flexure, thereby providing further evidence that a purely elastic lithospheric response cannot explain the deflection in this region. The relationship between the modeled elastic response and the GLAS derived flexure is applied to a long-term lake load change dataset to create the longest-running flexural response curve as caused by the last ∼40 years of Siling Co load variations, and these results show an accumulated lake-adjacent flexure of ∼12.6 cm from an

  17. Due diligence

    International Nuclear Information System (INIS)

    Sanghera, G.S.

    1999-01-01

    The Occupational Health and Safety (OHS) Act requires that every employer shall ensure the health and safety of workers in the workplace. Issues regarding the practices at workplaces and how they should reflect the standards of due diligence were discussed. Due diligence was described as being the need for employers to identify hazards in the workplace and to take active steps to prevent workers from potentially dangerous incidents. The paper discussed various aspects of due diligence including policy, training, procedures, measurement and enforcement. The consequences of contravening the OHS Act were also described

  18. Bevacizumab as a treatment option for radiation-induced cerebral necrosis

    Energy Technology Data Exchange (ETDEWEB)

    Matuschek, Christiane; Boelke, Edwin; Budach, Wilfried [Univ. Hospital Duesseldorf (Germany). Dept. of Radiation Oncology; Nawatny, Jens [Univ. Hospital Duesseldorf (Germany). Dept. of Radiology; Hoffmann, Thomas K. [Duisburg-Essen Univ., Essen (Germany). Dept. of Otorhinolaryngology; Peiper, Matthias; Orth, Klaus [Hospital Essen-Sued, Essen (Germany). Dept. of Surgery; Gerber, Peter Arne [Univ. Hospital Duesseldorf (Germany). Dept. of Dermatology; Rusnak, Ethelyn [State Univ. of New York, Buffalo, NY (United States). Dept. of Anesthesiology; Lammering, Guido [Univ. Hospital Duesseldorf (Germany). Dept. of Radiation Oncology; MAASTRO Clinic, Maastricht (Netherlands). Radiation Oncology

    2011-02-15

    Radiation necrosis of normal CNS tissue represents one of the main risk factors of brain irradiation, occurring more frequently and earlier at higher total doses and higher doses per fraction. At present, it is believed that the necrosis results due to increasing capillary permeability caused by cytokine release leading to extracellular edema. This process is sustained by endothelial dysfunction, tissue hypoxia, and subsequent necrosis. Consequently, blocking the vascular endothelial growth factor (VEGF) at an early stage could be an option to reduce the development of radiation necrosis by decreasing the vascular permeability. This might help to reverse the pathological mechanisms, improve the symptoms and prevent further progression. A patient with radiation-induced necrosis was treated with an anti-VEGF antibody (bevacizumab), in whom neurologic signs and symptoms improved in accordance with a decrease in T1-weighted fluid-attenuated inversion recovery signals. Our case report together with the current literature suggests bevacizumab as a treatment option for patients with symptoms and radiological signs of cerebral necrosis induced by radiotherapy. (orig.)

  19. Bevacizumab as a treatment option for radiation-induced cerebral necrosis

    International Nuclear Information System (INIS)

    Matuschek, Christiane; Boelke, Edwin; Budach, Wilfried; Nawatny, Jens; Hoffmann, Thomas K.; Peiper, Matthias; Orth, Klaus; Gerber, Peter Arne; Rusnak, Ethelyn; Lammering, Guido; MAASTRO Clinic, Maastricht

    2011-01-01

    Radiation necrosis of normal CNS tissue represents one of the main risk factors of brain irradiation, occurring more frequently and earlier at higher total doses and higher doses per fraction. At present, it is believed that the necrosis results due to increasing capillary permeability caused by cytokine release leading to extracellular edema. This process is sustained by endothelial dysfunction, tissue hypoxia, and subsequent necrosis. Consequently, blocking the vascular endothelial growth factor (VEGF) at an early stage could be an option to reduce the development of radiation necrosis by decreasing the vascular permeability. This might help to reverse the pathological mechanisms, improve the symptoms and prevent further progression. A patient with radiation-induced necrosis was treated with an anti-VEGF antibody (bevacizumab), in whom neurologic signs and symptoms improved in accordance with a decrease in T1-weighted fluid-attenuated inversion recovery signals. Our case report together with the current literature suggests bevacizumab as a treatment option for patients with symptoms and radiological signs of cerebral necrosis induced by radiotherapy. (orig.)

  20. Effects of Core Softness and Bimodularity of Fibreglass Layers on Flexural Stiffness of Polymer Sandwich Structures

    Directory of Open Access Journals (Sweden)

    Šuba Oldřich

    2017-01-01

    Full Text Available This paper deals with the study of the flexural stiffness of the sandwich structures based on fibreglass and polymeric foams. The influence of geometrical and material parameters on the resulting effective flexural stiffness of the sandwich structure is being studied experimentally, analytically and by using FEM models. The effective modulus of elasticity of the sandwich-structured element is being studied and its theoretical and model dependencies on the flexibility of the foam core and bimodularity of the fibreglass layers are being investigated. The achieved results are compared with the experimentally observed values. This study shows that it is necessary to pay special attention to the issue of flexural stiffness of the walls when designing sandwich shell products in order to prevent possible failures in the practical applications of these types of structures.

  1. Flexural-torsional buckling analysis of angle-bar stiffened plates

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Rahbar Ranji [Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2015-09-15

    The interaction of flexural-torsional buckling modes is critical for stiffened plates with asymmetric stiffeners. However, this interaction is ignored in all design rules because it is complex to characterize. In the literature, the presence of an attached plate is ignored, and stiffened plate is treated as an ordinary asymmetric beam. In the flexural buckling mode, stiffener and the attached plate buckle together; in the torsional buckling mode, the attached plate cannot freely rotate with stiffener. Basic equations of the flexural-torsional buckling modes are deduced based on hybrid beam concept and a new strain distribution assumption for sideway bending of stiffeners. Elastic buckling stresses of different angle-bar stiffened plates are calculated and compared with those generated by the Finite element method (FEM) and those available in the literature. The present method has better agreements with FEM.

  2. The Statistical Analysis of Relation between Compressive and Tensile/Flexural Strength of High Performance Concrete

    Directory of Open Access Journals (Sweden)

    Kępniak M.

    2016-12-01

    Full Text Available This paper addresses the tensile and flexural strength of HPC (high performance concrete. The aim of the paper is to analyse the efficiency of models proposed in different codes. In particular, three design procedures from: the ACI 318 [1], Eurocode 2 [2] and the Model Code 2010 [3] are considered. The associations between design tensile strength of concrete obtained from these three codes and compressive strength are compared with experimental results of tensile strength and flexural strength by statistical tools. Experimental results of tensile strength were obtained in the splitting test. Based on this comparison, conclusions are drawn according to the fit between the design methods and the test data. The comparison shows that tensile strength and flexural strength of HPC depend on more influential factors and not only compressive strength.

  3. Adaptive Kalman Filter of Transfer Alignment with Un-modeled Wing Flexure of Aircraft

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The alignment accuracy of the strap-down inertial navigation system (SINS) of airborne weapon is greatly degraded by the dynamic wing flexure of the aircraft. An adaptive Kalman filter uses innovation sequences based on the maximum likelihood estimated criterion to adapt the system noise covariance matrix and the measurement noise covariance matrix on line, which is used to estimate the misalignment if the model of wing flexure of the aircraft is unknown. From a number of simulations, it is shown that the accuracy of the adaptive Kalman filter is better than the conventional Kalman filter, and the erroneous misalignment models of the wing flexure of aircraft will cause bad estimation results of Kalman filter using attitude match method.

  4. FLEXURAL PROPERTIES OF ALKALINE TREATED SUGAR PALM FIBRE REINFORCED EPOXY COMPOSITES

    Directory of Open Access Journals (Sweden)

    D. Bachtiar

    2010-06-01

    Full Text Available A study of the effect of alkaline treatment on the flexural properties of sugar palm fibre reinforced epoxy composites is presented in this paper. The composites were reinforced with 10% weight fraction of the fibres. The fibres were treated using sodium hydroxide (NaOH with 0.25 M and 0.5 M concentration solution for 1 hour, 4 hours and 8 hours soaking time. The purpose of treating fibres with alkali was to enhance the interfacial bonding between matrix and fibre surfaces. The maximum flexural strength occurred at 0.25 M NaOH solution with 1 hour of soaking time, i.e 96.71 MPa, improving by 24.41% from untreated fibre composite. But, the maximum flexural modulus took place at 0.5 M NaOH solution with 4 hours soaking time, i.e. 6948 MPa, improving by 148% from untreated composite.

  5. Influence of Specimen Preparation and Test Methods on the Flexural Strength Results of Monolithic Zirconia Materials.

    Science.gov (United States)

    Schatz, Christine; Strickstrock, Monika; Roos, Malgorzata; Edelhoff, Daniel; Eichberger, Marlis; Zylla, Isabella-Maria; Stawarczyk, Bogna

    2016-03-09

    The aim of this work was to evaluate the influence of specimen preparation and test method on the flexural strength results of monolithic zirconia. Different monolithic zirconia materials (Ceramill Zolid (Amann Girrbach, Koblach, Austria), Zenostar ZrTranslucent (Wieland Dental, Pforzheim, Germany), and DD Bio zx² (Dental Direkt, Spenge, Germany)) were tested with three different methods: 3-point, 4-point, and biaxial flexural strength. Additionally, different specimen preparation methods were applied: either dry polishing before sintering or wet polishing after sintering. Each subgroup included 40 specimens. The surface roughness was assessed using scanning electron microscopy (SEM) and a profilometer whereas monoclinic phase transformation was investigated with X-ray diffraction. The data were analyzed using a three-way Analysis of Variance (ANOVA) with respect to the three factors: zirconia, specimen preparation, and test method. One-way ANOVA was conducted for the test method and zirconia factors within the combination of two other factors. A 2-parameter Weibull distribution assumption was applied to analyze the reliability under different testing conditions. In general, values measured using the 4-point test method presented the lowest flexural strength values. The flexural strength findings can be grouped in the following order: 4-point strength values than prepared before sintering. The Weibull moduli ranged from 5.1 to 16.5. Specimens polished before sintering showed higher surface roughness values than specimens polished after sintering. In contrast, no strong impact of the polishing procedures on the monoclinic surface layer was observed. No impact of zirconia material on flexural strength was found. The test method and the preparation method significantly influenced the flexural strength values.

  6. Biaxial flexural strength of Turkom-Cera core compared to two other all-ceramic systems

    Directory of Open Access Journals (Sweden)

    Bandar Mohammed Abdullah Al-Makramani

    2010-12-01

    Full Text Available Advances in all-ceramic systems have established predictable means of providing metal-free aesthetic and biocompatible materials. These materials must have sufficient strength to be a practical treatment alternative for the fabrication of crowns and fixed partial dentures. OBJECTIVES: The aim of this study was to compare the biaxial flexural strength of three core ceramic materials. MATERIAL AND METHODS: Three groups of 10 disc-shaped specimens (16 mm diameter x 1.2 mm thickness - in accordance with ISO-6872, 1995 were made from the following ceramic materials: Turkom-Cera Fused Alumina [(Turkom-Ceramic (M Sdn Bhd, Puchong, Selangor, Malaysia], In-Ceram (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany and Vitadur-N (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany, which were sintered according to the manufacturer's recommendations. The specimens were subjected to biaxial flexural strength test in an universal testing machine at a crosshead speed of 0.5 mm/min. The definitive fracture load was recorded for each specimen and the biaxial flexural strength was calculated from an equation in accordance with ISO-6872. RESULTS: The mean biaxial flexural strength values were: Turkom-Cera: 506.8±87.01 MPa, In-Ceram: 347.4±28.83 MPa and Vitadur-N: 128.7±12.72 MPa. The results were analyzed by the Levene's test and Dunnett's T3 post-hoc test (SPSS software V11.5.0 for Windows, SPSS, Chicago, IL, USA at a preset significance level of 5% because of unequal group variances (P<0.001. There was statistically significant difference between the three core ceramics (P<0.05. Turkom-Cera showed the highest biaxial flexural strength, followed by In-Ceram and Vitadur-N. CONCLUSIONS: Turkom-Cera core had significantly higher flexural strength than In-Ceram and Vitadur-N ceramic core materials.

  7. Effect of gas release in hot molding on flexural strength of composite friction brake

    Science.gov (United States)

    Rusdja, Andy Permana; Surojo, Eko; Muhayat, Nurul; Raharjo, Wijang Wisnu

    2018-02-01

    Composite friction brake is a vital part of braking system which serves to reduce the speed of vehicle. To fulfill the requirement of brake performance, composite friction brake must have friction and mechanical characteristic as required. The characteristics of composite friction brake are affected by brake material formulation and manufacturing parameter. In the beginning of hot molding, intermittent hot pressing was carried out to release the gases that consist of ammonia gas and water vapor. In composite friction brake, phenolic resin containing hexamethylenetetramine (HMTA) is often used as a binder. During hot molding, the reaction of phenolic resin and HMTA forms ammonia gas. Hot molding also generates water vapor because raw materials absorb moisture from environment when they are placed in storage. The gas release in hot molding is supposed affecting mechanical properties because it avoid entrapped gas in composite, so that this research investigated effect of gas release on flexural strength. Manufacturing of composite specimen was carried out as follow: mixing of raw materials, cold molding, and hot molding. In this research, duration of intermittent hot pressing and number of gas release were varied. The flexural strength of specimen was measured using three point bending test. The results showed that flexural strength specimens that were manufactured without gas release, using 4 times gas release with intermittent hot pressing for 5 and 10 seconds were not remarkably different. Conversely, hot molding using 4 times gas release with intermittent hot pressing for 15 seconds decreased flexural strength of composite. Hot molding using 2, 4, and 8 times gas release with intermittent hot pressing for 10 seconds also had no effect on increasing flexural strength. Increasing of flexural strength of composite was obtained only by using 6 times gas release with intermittent hot pressing for 10 seconds.

  8. Effect of cavity preparation on the flexural strengths of acrylic resin repairs

    Science.gov (United States)

    ELHADIRY, Safa Salim; YUNUS, Norsiah; ARIFFIN, Yusnidar Tajul

    2010-01-01

    Objective To investigate the effect of cavity preparation on the flexural strength of heat-curing denture resin when repaired with an auto-curing resin. Material and methods Ninety-six rectangular specimens (64x10x2.5 mm) prepared from heat-curing denture base resin (Meliodent) were randomly divided into four groups before repair. One group was left intact as control. Each repair specimen was sectioned into two; one group was repaired using the conventional repair method (Group 1). Two groups had an additional transverse cavity (2x3.5x21.5 mm) prepared prior to the repair; one repaired with (Group 2) and one without glass-fiber reinforcement (Group 3). A three-point flexural bending test according to the ISO 1567:1999 specification8 for denture base polymers was carried out on all groups after 1, 7 and 30 days of water immersion. Statistical analysis was carried out using two-way ANOVA, Kruskal Wallis and post-hoc Mann Whitney tests. Results The highest flexural strength was observed in the control group. Control and conventional repairs group (Group 1) showed reduction in the flexural strength 30 days after water immersion. No significant change in the strength was observed for Groups 2 and 3 where the repair joints were similarly prepared with additional transverse cavity. Conclusion Repaired specimens showed lower flexural strength values than intact heat-curing resin. Cavity preparation had no significant effect on the flexural strength of repair with water immersion. PMID:21308283

  9. Effect of tooth whitening strips on fatigue resistance and flexural strength of bovine dentin in vitro.

    Directory of Open Access Journals (Sweden)

    Laura E Tam

    Full Text Available To determine the effects of whitening strips on bovine dentin fatigue resistance and flexural strength in vitro.A total of eighty bovine dentin specimens (2x2x17mm were treated with either: control glycerine gel on plastic film wrap or whitening strips containing 9.5% hydrogen peroxide. Treatment was applied for 30 minutes, twice a day, for 1- or 4-weeks. After the last treatment, ten specimens per group were randomly selected to undergo fatigue testing (106 cycles, 3Hz, 20N while the other ten were subjected to flexural strength testing after ten days of storage in artificial saliva. Kaplan-Meier method with a log rank test, Wilcoxon test and Cox regression were used to assess fatigue test results (p<0.05. One-way ANOVA and Tukey's tests were used to compare the flexural strength results (p<0.05.There were significant differences in survival during the fatigue test among the groups (p<0.001. Treatment (control or bleach was a significant factor for specimen survival (p<0.001, Exp(B = 33.45. There were significant differences in mean flexural strength (p<0.001. No significant difference was found between "1-wk control" and "4-wk control". The mean flexural strength and fatigue resistance of the "4-wk bleach" were significantly lower than all the other groups.The use of whitening strips reduced the fatigue resistance and flexural strength of bovine dentin in vitro. Until the effect of whitening strips on mechanical properties of human dentin is fully elucidated, it remains prudent to advise patients to avoid excessive direct use of whitening strips on dentin.

  10. Deflection and Flexural Strength Effects on the Roughness of Aesthetic-Coated Orthodontic Wires.

    Science.gov (United States)

    Albuquerque, Cibele Gonçalves de; Correr, Américo Bortolazzo; Venezian, Giovana Cherubini; Santamaria, Milton; Tubel, Carlos Alberto; Vedovello, Silvia Amélia Scudeler

    2017-01-01

    The aim was to evaluate the flexural strength and the effects of deflection on the surface roughness of esthetic orthodontic wires. The sample consisted of 70 archwire 0.014-inch: polytetrafluorethylene (PTFE)-coated Nickel-Titanium (Niti) archwires (Titanol Cosmetic-TC, Flexy Super Elastic Esthetic-FSE, esthetic Nickel Titanium Wire-ANT); epoxy resin-coated Niti archwires (Spectra-S, Niticosmetic-TEC); gold and rhodium coated Niti (Sentalloy-STC) and a control group (superelastic Niti (Nitinol-NS). The initial roughness was evaluated with a rugosimeter. After that, the wires were submitted to flexural test in an universal testing machine. Each wire was deflected up to 2 mm at a speed of 1 mm/min. After flexural test, the roughness of the wires was evaluted on the same surface as that used for the initial evaluation. The data of roughness and flexural strength were analyzed by one-way ANOVA and Tukey's test (a=0.05). Student t-test compared roughness before and after deflection (a =0.05). The roughness of S and ANT (epoxy resin and PTFE-coated wires, respectively), before and after deflection, was significantly higher than the other groups (p<0.05). Wire deflection significantly increased the roughness of the wires S and STC (p<0.05). The flexural strength of groups FSE and NS (PTFE and uncoated) was higher compared with that of the other groups (p<0.05). We concluded that the roughness and flexural strength of the orthodontic wires does not depend on the type of the esthetic coating, but it is influenced by the method of application of this coating. The deflection can increase the roughness of the esthetic orthodontic wires.

  11. Effect of Titanium dioxide nanoparticles on the flexural strength of polymethylmethacrylate: an in vitro study.

    Science.gov (United States)

    Harini, P; Mohamed, Kasim; Padmanabhan, T V

    2014-01-01

    To improve the flexural strength of polymethylmethacrylate (PMMA). To evaluate whether the incorporation of titanium dioxide nanoparticles in polymethylmethacrylate (PMMA) increases the flexural strength and to compare the different concentrations of titanium dioxide nanoparticles and its relation to flexural strength. Study was conducted in Sri Ramachandra University utilizing 40 specimens manufactured from clear heat polymerizing acrylic resin. Forty specimens of clear heat polymerizing acrylic resin of dimensions 65 Χ 10 Χ 3 mm as per ISO 1,567 standardization were fabricated and were grouped into A (CONTROL) with no titanium dioxide (TiO2) nanoparticles, B with 0.5 gms of TiO 2 nanoparticles, C with 1 gm of TiO 2 nanoparticles and D with 2.5 gms of TiO 2 nanoparticles added.The concentrations of titanium dioxide in each group were 1 wt%, 2 wt% and 5 wt%. Universal testing machine INSTRON was used to load at the center of the specimen with a cross head speed of 1.50 mm/min and a span length of 40.00 mm. ANOVA and multiple comparisons are carried out using the independent t-test. The ANOVA result shows that there is a significant difference between the groups with respect to the mean flexural strength. Highest mean flexural strength is observed in Group D, while the lowest is seen in Group A. Independent t-test revealed that there was a statistical significance between Group A and Group D (0.041) and between Group B and Group D (0.028). The results concluded that polymethylmethacrylate reinforced with different concentrations of titanium dioxide nanoparticles showed superior flexural strength than those of normal PMMA.

  12. A comparison on the flexural strength of a new dental porcelain (D.} Dentin with Vita company Dentin porcelain (VMK 68N

    Directory of Open Access Journals (Sweden)

    Ghahramanloo A.

    2004-06-01

    Full Text Available Statement of Problem: Dental porcelain is one of the best materials ever used in dentistry. Excellent tissue"ncompatibility, esthetics, very low solubility in oral fluids, high compressive strength, and the lowest bacterial"nplaque accumulation on the glazed porcelain are some of its advantages. Porcelain brittleness due to its low"ntensile strength, impact strength and the occlusal attrition of opposing teeth enamel are some of its"ndisadvantages. The most important mechanical properties of dental porcelains are their flexural strength that is"nthe ability of a porcelain to resist fracture when loaded from above. Different ways have been proposed to"neliminate porcelain brittleness and develop its flexural strength, among which baking porcelain on a metal"nframework is more commonly used."nPurpose: Considering that restoration and replacement of teeth by porcelain fused to metal restorations is still"nthe most commonly used technique, the aim of the present study was to measure the flexural strength of a"nporcelain bonded to metal powder, D4 Dentin, and to compare it with Vita Dentin powder."nMaterials and Methods: In this experimental study, a stainless steel box, 25x5x2mm was made according to"nISO 6872: 1995 (E Standard and filled with D4 Dentin powder and Vita Dentin (VMK 68N and baked in"nVita furnace. Then 10 blocks of D^ Dentin and 10 of Vita Dentin were made. Samples were placed on the"nthree point bending test machine and force was applied the middle of each block. To analyze the data, t-"nstudent test and co-variance analysis were used."nResults: Mean flexural strength of D4 Dentin was 53.40±1.35 MPa and that of Vita Dentin was 53.86+7.38"nMPa. The difference was not statistically significant."nConclusion: According to ISO 6872: 1995 (E standard, the flexural strength of all D4 Dentin samples were"ngreater than 50 Mpa.

  13. Flexural behaviour of partially bonded carbon fibre reinforced polymers strengthened concrete beams: Application to fire protection systems design

    International Nuclear Information System (INIS)

    Firmo, J.P.; Arruda, M.R.T.; Correia, J.R.; Tiago, C.

    2015-01-01

    evaluated. The results obtained show that the strength reduction decreases when the ratio l b /L increases; the loading type does not present a relevant influence on the strength reduction; and, for similar l b /L ratios, the strength reduction suffered by NSM-strengthened beams is lower than that of EBR-strengthened beams. Relations between the strength reduction due to the partial bonding and the l b /L ratio were defined for both loading cases and strengthening techniques. These results, obtained at ambient temperature, were then incorporated in a simplified procedure that is proposed for the design of fire protection systems of CFRP-strengthened RC flexural members

  14. Avascular necrosis ofbone following renal transplantation

    African Journals Online (AJOL)

    and avascular necrosis was reported in 1957 in a patient ... Onset of pain ranged from 2 months to 36 months .... and corticosteroid-induced diabetes); (iv) severe sec- ... reponed in the shoulder and elbow joints, i.e. humeral head, distal ...

  15. Aseptic necrosis of femoral head complicating thalassemia

    International Nuclear Information System (INIS)

    Orzincolo, C.; Castaldi, G.; Scutellary, P.N.; Bariani, L.; Pinca, A.

    1986-01-01

    Aseptic necrosis of the femoral head is described in 4 patients, selected from 280 patients with homozygous β-thalassemia (Cooley anemia). The incidence of the complication appears to be very high (14.5per mille) in thalassemia, compared to the general population. The possible mechanism are discussed. (orig.)

  16. Colonic ischemic necrosis following therapeutic embolization

    International Nuclear Information System (INIS)

    Shenoy, S.S.; Satchidanand, S.; Wesp, E.H.; State Univ. of New York, Buffalo

    1981-01-01

    Transcatheter embolization of the middle colic artery for diverticular bleeding was followed by ischemic necrosis in the transverse colon at the site of previous anastomosis and stricture formation. This is a potential complication of intra-arterial embolization for colonic bleeding. (orig.)

  17. [Acute unclassified leukemia with bone marrow necrosis].

    Science.gov (United States)

    Uoshima, N; Yamazaki, N; Iinuma, S; Kimura, S; Wada, K; Kobayashi, Y; Ozawa, M; Horiuchi, H; Maruo, N; Kondo, M

    1991-01-01

    Massive bone marrow necrosis was seen in a 42-year-old male with acute leukemia. In December, 1988, on admission, laboratory data revealed pancytopenia and a high level of serum LDH and ALKP. Bone marrow aspiration resulted in dry-tap and showed bone marrow necrosis in the bone marrow biopsy specimen. A bone marrow scintigraphy with 111In faintly visualized the bone marrow but visualized area was expanded in the extremities compared with normal subjects. The second bone marrow biopsy showed proliferation of blasts. In the middle of March, blasts began to appear in peripheral blood. The blasts were cytochemically negative for POX, Es, PAS, AcP, TdT and had surface markers CD3-, CD19-, CD33-, CD13-, LCA-, HLA-DR-. Even by investigation on rearrangement of the immunoglobulin heavy chain region, an origin of the blasts could not be determined. In April, the number of blasts in peripheral blood increased and hepatosplenomegaly developed rapidly. Therefore, he was put on the chemotherapy with vincristine and prednisolone, but he died of cerebral hemorrhage. The autopsy revealed widespread bone marrow necrosis. It has rarely been reported that massive bone marrow necrosis is found prior to the occurrence of acute unclassified leukemia.

  18. Colonic ischemic necrosis following therapeutic embolization

    Energy Technology Data Exchange (ETDEWEB)

    Shenoy, S S; Satchidanand, S; Wesp, E H

    1981-07-15

    Transcatheter embolization of the middle colic artery for diverticular bleeding was followed by ischemic necrosis in the transverse colon at the site of previous anastomosis and stricture formation. This is a potential complication of intra-arterial embolization for colonic bleeding.

  19. Development of delayed radiation necrosis. Case report

    Energy Technology Data Exchange (ETDEWEB)

    Ohara, ShigFeki; Takagi, Terumasa [Meitetsu Hospital, Nagoya (Japan); Shibata, Taichiro; Nagai, Hajime

    1983-04-01

    The authors discussed the developing process of delayed radiation necrosis of the brain from the case of a 42-year-old female who developed intracranial hypertension and left hemiparesis 5 and a half years after radiotherapy for pituitary adenoma. The initial sign of radiation necrosis was from a CT scan taken 3 and a half years after radiotherapy showing an irregular low density lesion in the right temporal lobe. CT scan 2 years later demonstrated displacement of the midline structures to the left and a larger low density lesion with partially high density in the right MCA territory that was enhanced with intravenous contrast medium. Recovery after a right temporal lobectomy and administration of steroid hormone were uneventful. Eight months later there were no signs of raised intracranial pressure nor of neurological deficits. Tissues obtained from the right temporal lobe at lobectomy revealed the characteristic changes of delayed radiation necrosis; a mixture of fresh, recent, and old vascular lesions in the same specimen. From these findings, it was speculated that delayed radiation necrosis might initially occur within several years after radiotherapy and might gradually take a progressive and extended course, even in cases whose clinical symptoms develop much later.

  20. Complete flexural vibration band gaps in membrane-like lattice structures

    International Nuclear Information System (INIS)

    Yu Dianlong; Liu Yaozong; Qiu Jing; Wang Gang; Zhao Honggang

    2006-01-01

    The propagation of flexural vibration in the periodical membrane-like lattice structure is studied. The band structure calculated with the plane wave expansion method indicates the existence of complete gaps. The frequency response function of a finite periodic structure is simulated with finite element method. Frequency ranges with vibration attenuation are in good agreement with the gaps found in the band structure. Much larger attenuations are found in the complete gaps comparing to those directional ones. The existence of complete flexural vibration gaps in such a lattice structure provides a new idea for vibration control of thin plates

  1. Late Cenozoic flexural deformation of the middle U.S. Atlantic passive margin

    Science.gov (United States)

    Pazzaglia, Frank J.; Gardner, Thomas, W.

    1994-01-01

    Despite the century-long recognition of regional epeirogeny along the middle Atlantic passive margin, relatively few studies have focused on understanding postrift uplift mechanisms. Here, we demonstrate that epeirogenic uplift of the central Appalachian Piedmont and subsidence of the Salisbury Embayment represent first-order, flexural isostatic processes driven by continental denudation and offshore deposition. Our results show that regional epeirogenic processes, present on all Atlantic-type passive margins, are best resolved by specific stratigraphic and geomorphic relationships, rather than topography. A simple one-dimensional geodynamic model, constrained by well-dated Baltimore Canyon trough, Coastal Plain, and lower Susquehanna River (piedmont) stratigraphy, simulates flexural deforamtion of the U.S. Atlantic margin. The model represents the passive margin lithosphree as a uniformly thick elastic plate, without horizontal compressive stresses, that deforms flexurally under the stress of strike-averaged, vertically applied line loads. Model results illustrate a complex interaction among margin stratigraphy and geomorphology, the isostatic repsonse to denudational and depositional processes, and the modulating influence of exogenic forces such as eustasy. The current elevation, with respect to modern sea level, of fluvial terraces and correlateive Coastal Plain deposits or unconformities is successfully predicted through the synthesis of paleotopography, eustatic change, and margin flexure. Results suggest that the middle U.S. Atlantic margin landward of East Coast Magnetic Anomaly is underlain by lithoshpere with an average elastic thickness of 40 km (flexural rigidity, D = 4 X 10(exp 23) N m), the margin experience an average, long-term denudation rate of approximately 10m/m.y., and the Piedmont has been flexurally upwaped between 35 and 130 meters in the last 15 m.y. Long term isostatic continental uplift resulting rom denudation and basin subsidence

  2. Invited review article: high-speed flexure-guided nanopositioning: mechanical design and control issues.

    Science.gov (United States)

    Yong, Y K; Moheimani, S O R; Kenton, B J; Leang, K K

    2012-12-01

    Recent interest in high-speed scanning probe microscopy for high-throughput applications including video-rate atomic force microscopy and probe-based nanofabrication has sparked attention on the development of high-bandwidth flexure-guided nanopositioning systems (nanopositioners). Such nanopositioners are designed to move samples with sub-nanometer resolution with positioning bandwidth in the kilohertz range. State-of-the-art designs incorporate uniquely designed flexure mechanisms driven by compact and stiff piezoelectric actuators. This paper surveys key advances in mechanical design and control of dynamic effects and nonlinearities, in the context of high-speed nanopositioning. Future challenges and research topics are also discussed.

  3. Omnidirectional refractive devices for flexural waves based on graded phononic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Torrent, Daniel, E-mail: daniel.torrent@iemn.univ-lille1.fr; Pennec, Yan; Djafari-Rouhani, Bahram [Institut d' Electronique, de Microléctronique et de Nanotechnologie, UMR CNRS 8520, Université de Lille 1, 59655 Villeneuve d' Ascq (France)

    2014-12-14

    Different omnidirectional refractive devices for flexural waves in thin plates are proposed and numerically analyzed. Their realization is explained by means phononic crystal plates, where a previously developed homogenization theory is employed for the design of graded index refractive devices. These devices consist of a circular cluster of inclusions with a properly designed gradient in their radius. With this approach, the Luneburg and Maxwell lenses and a family of beam splitters for flexural waves are proposed and analyzed. Results show that these devices work properly in a broadband frequency region, being therefore an efficient approach for the design of refractive devices specially interesting for nano-scale applications.

  4. Clinical and CT imaging features of abdominal fat necrosis

    International Nuclear Information System (INIS)

    Zhao Jinkun; Bai Renju

    2013-01-01

    Fat necrosis is a common pathological change at abdominal cross-sectional imaging, and it may cause abdominal pain, mimic pathological change of acute abdomen, or be asymptomatic and accompany other pathophysiologic processes. Fat necrosis is actually the result of steatosis by metabolism or mechanical injury. Common processes that are present in fat necrosis include epiploic appendagitis, infarction of the greater omentum, pancreatitis, and fat necrosis related to trauma or ischemia. As a common fat disease, fat necrosis should be known by clinicians and radiologists. Main content of this text is the clinical symptoms and CT findings of belly fat necrosis and related diseases. (authors)

  5. Flexural toughness of steel fiber reinforced high performance concrete containing nano-SiO2 and fly ash.

    Science.gov (United States)

    Zhang, Peng; Zhao, Ya-Nan; Li, Qing-Fu; Wang, Peng; Zhang, Tian-Hang

    2014-01-01

    This paper aims to clarify the effect of steel fiber on the flexural toughness of the high performance concrete containing fly ash and nano-SiO2. The flexural toughness was evaluated by two methods, which are based on ASTM C1018 and DBV-1998, respectively. By means of three-point bending method, the flexural toughness indices, variation coefficients of bearing capacity, deformation energy, and equivalent flexural strength of the specimen were measured, respectively, and the relational curves between the vertical load and the midspan deflection (P(V)-δ) were obtained. The results indicate that steel fiber has great effect on the flexural toughness parameters and relational curves (P(V)-δ) of the three-point bending beam specimen. When the content of steel fiber increases from 0.5% to 2%, the flexural toughness parameters increase gradually and the curves are becoming plumper and plumper with the increase of steel fiber content, respectively. However these flexural toughness parameters begin to decrease and the curves become thinner and thinner after the steel fiber content exceeds 2%. It seems that the contribution of steel fiber to the improvement of flexural toughness of the high performance concrete containing fly ash and nano-SiO2 is well performed only when the steel fiber content is less than 2%.

  6. Influence of nonmetals recycled from waste printed circuit boards on flexural properties and fracture behavior of polypropylene composites

    International Nuclear Information System (INIS)

    Zheng Yanhong; Shen Zhigang; Cai Chujiang; Ma Shulin; Xing Yushan

    2009-01-01

    Flexural strength and flexural modulus of the composites can be successfully improved by filling nonmetals recycled from waste printed circuit boards (PCBs) into polypropylene (PP). By using scanning electron microscopy (SEM), the influence of nonmetals on fracture behavior of PP composites is investigated by in situ flexural test. Observation results show that the particles can effectively lead to mass micro cracks instead of the breaking crack. The process of the crack initiation, propagation and fiber breakage dissipate a great amount of energy. As a result, the flexural properties of the composites can be reinforced significantly. Results of the in situ SEM observation and analysis to the dynamic flexural process supply effective test evidence for the reinforcing mechanism of the nonmetals/PP composites on the basis of the energy dissipation theory

  7. [The effect of core veneer thickness ratio on the flexural strength of diatomite-based dental ceramic].

    Science.gov (United States)

    Jiang, Jie; Zhang, Xin; Gao, Mei-qin; Zhang, Fei-min; Lu, Xiao-li

    2015-06-01

    To evaluate the effect of different core veneer thickness ratios on the flexural strength and failure mode of bilayered diatomite-based dental ceramics. Diatomite-based dental ceramics blocks (16 mm×5.4 mm×1 mm) were sintered with different thickness of veneer porcelains: 0 mm (group A), 0.6 mm (group B), 0.8 mm (group C) and 1.0 mm (group D). Flexural strength was detected and scanning electron microscope was used to observe the interface microstructure. Statistical analysis was performed using SPSS 17.0 software package. With the increase of the thickness of the veneer porcelain, flexural strength of group C showed highest flexural strength up to (277.24±5.47) MPa. Different core veneer thickness ratios can significantly influence the flexural strength of bilayered diatomite-based dental ceramics. Supported by Science and Technology Projects of Nantong City (HS2013010).

  8. Geological and 40Ar/39Ar age constraints on late-stage Deccan rhyolitic volcanism, inter-volcanic sedimentation, and the Panvel flexure from the Dongri area, Mumbai

    Science.gov (United States)

    Sheth, Hetu C.; Pande, Kanchan

    2014-04-01

    Post-K-Pg Boundary Deccan magmatism is well known from the Mumbai area in the Panvel flexure zone. Represented by the Salsette Subgroup, it shows characters atypical of much of the Deccan Traps, including rhyolite lavas and tuffs, mafic tuffs and breccias, spilitic pillow basalts, and "intertrappean" sedimentary or volcanosedimentary deposits, with mafic intrusions as well as trachyte intrusions containing basaltic enclaves. The intertrappean deposits have been interpreted as formed in shallow marine or lagoonal environments in small fault-bounded basins due to syn-volcanic subsidence. We report a previously unknown sedimentary deposit underlying the Dongri rhyolite flow from the upper part of the Salsette Subgroup, with a westerly tectonic dip due to the Panvel flexure. We have obtained concordant 40Ar/39Ar ages of 62.6 ± 0.6 Ma (2σ) and 62.9 ± 0.2 Ma (2σ) for samples taken from two separate outcrops of this rhyolite. The results are significant in showing that (i) Danian inter-volcanic sedimentary deposits formed throughout Mumbai, (ii) the rock units are consistent with the stratigraphy postulated earlier for Mumbai, (iii) shale fragments known in some Dongri tuffs were likely derived from the sedimentary deposit under the Dongri rhyolite, (iv) the total duration of extrusive and intrusive Deccan magmatism was at least 8-9 million years, and (v) Panvel flexure formed, or continued to form, after 63 Ma, possibly even 62 Ma, and could not have formed by 65-64 Ma as concluded in a recent study.

  9. Research on differences and correlation between tensile, compression and flexural moduli of cement stabilized macadam

    Directory of Open Access Journals (Sweden)

    Yi Yang

    2017-07-01

    Full Text Available In order to reveal the differences and conversion relations between the tensile, compressive and flexural moduli of cement stabilized macadam, in this paper, we develop a new test method for measuring three moduli simultaneously. By using the materials testing system, we test three moduli of the cement stabilized macadam under different loading rates, propose a flexural modulus calculation formula which considers the shearing effect, reveal the change rules of the tensile, compression and flexural moduli with the loading rate and establish the conversion relationships between the three moduli. The results indicate that: three moduli become larger with the increase of the loading rate, showing a power function pattern; with the shear effect considered, the flexural modulus is increased by 47% approximately over that in the current test method; the tensile and compression moduli of cement stabilized macadam are significantly different. Therefore, if only the compression modulus is used as the structural design parameter of asphalt pavement, there will be a great deviation in the analysis of the load response. In order to achieve scientific design and calculation, the appropriate design parameters should be chosen based on the actual stress state at each point inside the pavement structure.

  10. A novel vibration assisted polishing device based on the flexural mechanism driven by the piezoelectric actuators

    Directory of Open Access Journals (Sweden)

    Guilian Wang

    2018-01-01

    Full Text Available The vibration assisted polishing has widely application fields because of higher machining frequency and better polishing quality, especially the polishing with the non-resonant mode that is regarded as a kind of promising polishing method. This paper reports a novel vibration assisted polishing device, consisting of the flexible hinge mechanism driven by the piezoelectric actuators, which is suitable for polishing planes or curve surfaces with slow curvature. Firstly, the generation methods of vibration trajectory are investigated for the same frequency and different frequency signals’ inputs, respectively, and then the types of elliptic and Lissajous’s vibration trajectories are generated respectively. Secondly, a flexural mechanism consisting of the right circular flexible hinges and the leaf springs is developed to produce two-dimensional vibration trajectory. Statics and dynamics investigating of this flexible mechanism are finished in detail. The analytical models about input and output compliances of the flexural mechanism are established according to the matrix-based compliance modeling, and the dynamic model of the flexural mechanism based on the Euler-Lagrange equation is also presented. The finite element model of the flexural mechanism was established to carry out the numerical simulation in order to testify the rationality of device design. Finally, the polishing experiment is carried out to prove the effectiveness of the vibration device. The experimental results show that this novel vibration assisted polishing device developed in this study can remove more effectively the cutting marks left by last process and obviously reduce the workpiece surface roughness.

  11. Evaluation of tension stiffening effect on the crack width calculation of flexural RC members

    Directory of Open Access Journals (Sweden)

    Said M. Allam

    2013-06-01

    Full Text Available Building codes consider the tension stiffening when calculating the crack width of the flexural members. A simple analytical procedure is proposed for the determination of forces, stresses and strains acting on a reinforced concrete section subjected to flexure considering the concrete contribution in tension up to tensile concrete strain corresponding to the cracking strength of concrete. This analytical method gives the minimum value (lower bound of tension stiffening. Also, a commercial Finite Element Program (ABAQUS 2007 was used to perform non-linear analysis in order to evaluate the total contribution of the tensioned concrete in carrying loads which may be considered as the upper bound of tension stiffening. In addition, a comparison is carried out among the different codes using four reinforced concrete rectangular models to compare and evaluate the tension stiffening with proposed analytical lower bound tension stiffening and upper bound as obtained by ABAQUS. The models include different percentages of flexural steel ratio. The comparison revealed that the codes’ equations always consider tension stiffening lying between lower and upper bound of tension stiffening proposed in this study. Also, the study showed that the tension stiffening decreases with the increase of the percentage of the flexural reinforcement ratio.

  12. Flexural properties and impact strength of denture base resins reinforced with micronized glass flakes

    Directory of Open Access Journals (Sweden)

    Ronak H Choksi

    2016-01-01

    Conclusion: Flexural strength of unmodified PMMA denture base resin decreases with increase in the concentration of glass flakes. Impact strength does not show any significant change at 5% concentration of glass flakes and impact strength significantly reduces with the addition of glass flakes in 10% and 20%.

  13. Flexure Behavior of Hybrid Continuous Deep Beam Strengthened by Carbon Fiber Reinforced Polymer

    Directory of Open Access Journals (Sweden)

    Hayder M.K.Al-Mutairee

    2017-08-01

    Full Text Available This study present an experimental investigation for overall flexure behavior of reinforced concrete continuous deep beams (RCCDB made of hybrid concrete, normal strength concrete (NSC and high strength concrete (HSC at different location and percentage. The experimental work includes testing of sixteen specimens of RCCDB under two points loads. The effects of HSC layer thickness and CFRP on strength of RCCDB had been studied. The experimental results showed that the strengthening of RCCDB by HSC layer from top is better than from bottom, where the increment in the ultimate flexural strength increased by (14,21,27% for top strengthening and (12,15,13% for bottom strengthening for (25,50,75% thickness of total depth of beam respectively. The optimal strengthening of RCCDB by HSC layer at top was of 25%. The results also proved that the strengthening of hybrid RCCDB by (10,15cm CFRP strip at the bottom for flexure gave increment in the ultimate strength by (32, 29% respectively, and the strengthening by CFRP strip for flexure at the bottom is better than at top for hybrid RCCDB. The shear strengthening of hybrid RCCDB increases the ultimate strength by 23.4% and 13.8% if the strengthening has O and U shape respectively

  14. Flexural Stiffness of Myosin Va Subdomains as Measured from Tethered Particle Motion

    Science.gov (United States)

    Michalek, Arthur J.; Kennedy, Guy G.; Warshaw, David M.; Ali, M. Yusuf

    2015-01-01

    Myosin Va (MyoVa) is a processive molecular motor involved in intracellular cargo transport on the actin cytoskeleton. The motor's processivity and ability to navigate actin intersections are believed to be governed by the stiffness of various parts of the motor's structure. Specifically, changes in calcium may regulate motor processivity by altering the motor's lever arm stiffness and thus its interhead communication. In order to measure the flexural stiffness of MyoVa subdomains, we use tethered particle microscopy, which relates the Brownian motion of fluorescent quantum dots, which are attached to various single- and double-headed MyoVa constructs bound to actin in rigor, to the motor's flexural stiffness. Based on these measurements, the MyoVa lever arm and coiled-coil rod domain have comparable flexural stiffness (0.034 pN/nm). Upon addition of calcium, the lever arm stiffness is reduced 40% as a result of calmodulins potentially dissociating from the lever arm. In addition, the flexural stiffness of the full-length MyoVa construct is an order of magnitude less stiff than both a single lever arm and the coiled-coil rod. This suggests that the MyoVa lever arm-rod junction provides a flexible hinge that would allow the motor to maneuver cargo through the complex intracellular actin network. PMID:26770194

  15. An experimental study of crack development in flexural reinforced concrete members

    DEFF Research Database (Denmark)

    Rasmussen, Annette Beedholm; Hagsten, Lars German; Würst Sørensen, Bjarke

    2017-01-01

    This paper presents the results of an experimental program of eight reinforced concrete beams carried out in order to investigate the development of cracks related to flexure. To be able to investigate possible size effects with respect to cracking, beams of two different depths were tested...

  16. Lower crustal seismic activity in the Adana Basin (Eastern Mediterranean): Possible connection to gravitational flexure

    Science.gov (United States)

    Ergin, Mehmet; Aktar, Mustafa

    2018-04-01

    High quality broadband data, together with the application of the double difference relocation technique, has been used to study the characteristics of the lower crustal seismicity in the Adana Basin, in southwestern Turkey. Deep events are clearly seen to be restricted only to the Adana Basin and never extend outside its boundaries. Furthermore, the seismogenic zone is observed to align roughly with the main axis of the basin and plunges steadily in the SSW-direction, following the basement trend of the Adana Basin. Similarities between geometries of the basin evolution and the deep seismic production suggest that both processes are closely related. A flexure process is proposed related to the subsidence of the Adana Basin. The seismogenic zone, originally at a shallow depth, is assumed to have been displaced vertically into the lower crust, by flexure. The temperature evolution of the crust during the flexure has been studied in detail using finite difference modeling, with amplitude and duration parameters taken from earlier studies. It has been concluded that the physical conditions for brittle fracturing remained unchanged for an extended period of time after the flexure. The brittle layers originally at shallow depths, preserved their original thermal properties after the subsidence and will continue to produce earthquakes at considerable depths. Numerical tests using inferred parameters imply a total vertical shift of 7-8 km for the seismogenic zone. Discussions for additional processes, which may further contribute to the cooling of the crust, are also included.

  17. Mechanical and thermal cycling effects on the flexural strength of glass ceramics fused to titanium

    NARCIS (Netherlands)

    Vasquez, Vanessa; Ozcan, Mutlu; Nishioka, Renato; Souza, Rodrigo; Mesquita, Alfredo; Pavanelli, Carlos

    This study evaluated the effects of mechanical and thermal cycling on the flexural strength (ISO 9693) of three brands of ceramics fused to commercially pure titanium (cpTi). Metallic frameworks of 25 x 3 x 0.5 mm dimensions (N = 84) were cast in cpTi, followed by 150-mu m aluminum oxide airborne

  18. Flexure and impact properties of glass fiber reinforced nylon 6-polypropylene composites

    Science.gov (United States)

    Kusaseh, N. M.; Nuruzzaman, D. M.; Ismail, N. M.; Hamedon, Z.; Azhari, A.; Iqbal, A. K. M. A.

    2018-03-01

    In recent years, polymer composites are rapidly developing and replacing the metals or alloys in numerous engineering applications. These polymer composites are the topic of interests in industrial applications such as automotive and aerospace industries. In the present research study, glass fiber (GF) reinforced nylon 6 (PA6)-polypropylene (PP) composite specimens were prepared successfully using injection molding process. Test specimens of five different compositions such as, 70%PA6+30%PP, 65%PA6+30%PP+5%GF, 60%PA6+30%PP+10%GF, 55%PA6+30%PP+15%GF and 50%PA6+30%PP+20%GF were prepared. In the experiments, flexure and impact tests were carried out. The obtained results revealed that flexure and impact properties of the polymer composites were significantly influenced by the glass fiber content. Results showed that flexural strength is low for pure polymer blend and flexural strength of GF reinforced composite increases gradually with the increase in glass fiber content. Test results also revealed that the impact strength of 70%PA6+30%PP is the highest and 55%PA6+30%PP+15%GF composite shows moderate impact strength. On the other hand, 50%PA6+30%PP+20%GF composite shows low toughness or reduced impact strength.

  19. Flexural strengthening of reinforced lightweight polystyrene aggregate concrete beams with near-surface mounted GFRP bars

    Energy Technology Data Exchange (ETDEWEB)

    Tang, W.C.; Balendran, R.V.; Nadeem, A.; Leung, H.Y. [City University of Hong Kong (China). Department of Building and Construction

    2006-10-15

    Application of near-surface mounted (NSM) fibre reinforced polymer (FRP) bars is emerging as a promising technology for increasing flexural and shear strength of deficient reinforced concrete (RC) members. In order for this technique to perform effectively, the structural behaviour of RC elements strengthened with NSM FRP bars needs to be fully characterized. This paper focuses on the characterization of flexural behaviour of RC members strengthened with NSM glass-FRP bars. Totally, 10 beams were tested using symmetrical two-point loads test. The parameters examined under the beam tests were type of concretes (lightweight polystyrene aggregate concrete and normal concrete), type of reinforcing bars (GFRP and steel), and type of adhesives. Flexural performance of the tested beams including modes of failure, moment-deflection response and ultimate moment capacity are presented and discussed in this paper. Results of this investigation showed that beams with NSM GFRP bars showed a reduction in ultimate deflection and an improvement in flexural stiffness and bending capacity, depending on the PA content of the beams. In general, beams strengthened with NSM GFRP bars overall showed a significant increase in ultimate moment ranging from 23% to 53% over the corresponding beams without NSM GFRP bars. The influence of epoxy type was found conspicuously dominated the moment-deflection response up to the peak moment. Besides, the ultimate moment of concrete beams reinforced with GFRP bars could be predicted satisfactorily using the equation provided in ACI 318-95 Building Code. (author)

  20. Segmental resection with primary anastomosis is not always safe in splenic flexure perforation.

    Science.gov (United States)

    Weledji, Elroy P; Mokake, Martin D; Sinju, Motaze

    2016-01-16

    Familial adenomatous polyposis (FAP) is caused by a rare mutation of the adenomatous polyposis coli gene on Chromosome 5q. The risk of colorectal cancer in patients with FAP is nearly 100% and intensive endoscopic surveillance or prophylactic colectomy are mandatory. If extensive endoscopic surveillance is chosen, there is a cumulative risk of perforation and bleeding especially after polypectomy. We discussed the problems and options in the management of the late diagnosis of an iatrogenic perforation of the splenic flexure complicating endoscopic surveillance in FAP. We present a 35-year-old black African man with FAP who sustained a splenic flexure perforation following a colonoscopic polypectomy of a suspicious lesion. He underwent a splenic flexure resection and primary anastomosis that dehisced and the patient benefited from an emergency definitive colectomy and ileorectal anastomosis. Resection with primary anastomosis following iatrogenic perforation of the splenic flexure is not safe because of a high chance of anastomotic dehiscence. Following a late diagnosis in an unstable patient exteriorization of the perforation as a stoma is a better option prior to a definitive prophylactic colectomy.

  1. Numerical modelling study on the flexural uplift of the Transantarctic Mountains

    NARCIS (Netherlands)

    Yamasaki, T.; Miura, H.; Nogi, Y.

    2008-01-01

    In this study, based on a 2-D thermomechanical finite element model, the uplift of the Transantarctic Mountains (TAM) is discussed in relation to the flexural uplift of a rheologically layered lithosphere, which is described by Vening-Meinesz's cantilever kinematics. The general model behaviour

  2. Fluoride release, recharge and flexural properties of polymethylmethacrylate containing fluoridated glass fillers.

    Science.gov (United States)

    Al-Bakri, I A; Swain, M V; Naoum, S J; Al-Omari, W M; Martin, E; Ellakwa, A

    2014-06-01

    The purpose of this study was to investigate the effect of fluoridated glass fillers on fluoride release, recharge and the flexural properties of modified polymethylmethacrylate (PMMA). Specimens of PMMA denture base material with various loading of fluoridated glass fillers (0%, 1%, 2.5%, 5% and 10% by weight) were prepared. Flexural properties were evaluated on rectangular specimens (n = 10) aged in deionized water after 24 hours, 1 and 3 months. Disc specimens (n = 10) were aged for 43 days in deionized water and lactic acid (pH 4.0) and fluoride release was measured at numerous intervals. After ageing, specimens were recharged and fluoride re-release was recorded at 1, 3 and 7 days after recharge. Samples containing 2.5%, 5% and 10% glass fillers showed significantly (p glass fillers specimens. All experimental specimens exhibited fluoride release in both media. The flexural strength of specimens decreased in proportion to the percentage filler inclusion with the modulus of elasticity values remaining within ISO Standard 1567. The modified PMMA with fluoridated glass fillers has the ability to release and re-release fluoride ion. Flexural strength decreased as glass filler uploading increased. © 2014 Australian Dental Association.

  3. Empirical studies of flexural strength for dry-stack Interlocking masonry

    African Journals Online (AJOL)

    Tests were carried out to establish the flexural strength of dry-stack masonry under vertical and horizontal bending. Two formats of wallettes were tested. Format 1 made of specimens constructed span normal to bed joints, which were tested under vertical bending and Format 2 specimens constructed span parallel to bed ...

  4. Determination of Bond Capacity in Reinforced Concrete Beam and Its Influence on the Flexural Strength

    Directory of Open Access Journals (Sweden)

    Mohammad Rashidi

    2016-05-01

    Full Text Available This paper presents results of an experimental investigation of actual performance of the reinforced concrete beam in bond under flexure, when reinforced with tension steel is going to consider. In this experiment four specimens of beam and a bar in the middle of the width of the beam has been used and 2.5 cm of concrete cover has been considered from the center of the bar. In addition, transverse bars have been used to reassure lack of shear yield at the two ends of the beam. Flexural bar has been put in the middle of the beam symmetrically and the length of the flexural bar in each of the samples shall be: 15, 20, 30 and 40 cm. Three cylindrical samples were made in order to determine f’c and were examined at 28 days and the compressive strength of concrete used in this study was about 35 MPa. The beam samples were examined after 28 days via two-point loading system. Based on the results, increasing the length of bar causes increase of flexural strength. The presence of longitudinal rebar resulted in the ultimate momentum to be more than the crack momentum of the cross-section in parts which have broken at the point of longitudinal bar cut.

  5. Multiple scattering and stop band characteristics of flexural waves on a thin plate with circular holes

    Science.gov (United States)

    Wang, Zuowei; Biwa, Shiro

    2018-03-01

    A numerical procedure is proposed for the multiple scattering analysis of flexural waves on a thin plate with circular holes based on the Kirchhoff plate theory. The numerical procedure utilizes the wave function expansion of the exciting as well as scattered fields, and the boundary conditions at the periphery of holes are incorporated as the relations between the expansion coefficients of exciting and scattered fields. A set of linear algebraic equations with respect to the wave expansion coefficients of the exciting field alone is established by the numerical collocation method. To demonstrate the applicability of the procedure, the stop band characteristics of flexural waves are analyzed for different arrangements and concentrations of circular holes on a steel plate. The energy transmission spectra of flexural waves are shown to capture the detailed features of the stop band formation of regular and random arrangements of holes. The increase of the concentration of holes is found to shift the dips of the energy transmission spectra toward higher frequencies as well as deepen them. The hexagonal hole arrangement can form a much broader stop band than the square hole arrangement for flexural wave transmission. It is also demonstrated that random arrangements of holes make the transmission spectrum more complicated.

  6. Enhanced Flexural Strength of Tellurium Nanowires/epoxy Composites with the Reinforcement Effect of Nanowires

    Science.gov (United States)

    Balguri, Praveen Kumar; Harris Samuel, D. G.; Aditya, D. B.; Vijaya Bhaskar, S.; Thumu, Udayabhaskararao

    2018-02-01

    Investigating the mechanical properties of polymer nanocomposite materials has been greatly increased in the last decade. In particular, flexural strength plays a major role in resisting bending and shear loads of a composite material. Here, one dimensional (1D) tellurium nanowires (TeNWs) reinforced epoxy composites have been prepared and the flexural properties of resulted TeNWs/epoxy nanocomposites are studied. The diameter and length of the TeNWs used to make TeNWs/epoxy nanocomposites are 21±2.5 nm and 697±87 nm, respectively. Plain and TeNWs/epoxy nanocomposites are characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). Furthermore, significant enhancement in the flexural strength of TeNWs/epoxy nanocomposite is observed in comparison to plain epoxy composite, i.e. flexural strength is increased by 65% with the addition of very little amount of TeNWs content (0.05 wt.%) to epoxy polymer. Structural details of plain and TeNWs/epoxy at micrometer scale were examined by scanning electron microscopy (SEM). We believe that our results provide a new type of semiconductor nanowires based high strength epoxy polymer nanocomposites.

  7. Evaluating the fracture toughness and flexural strength of pressable dental ceramics: an in vitro study.

    Science.gov (United States)

    Gurram, Ravi; Krishna, C H Vamsi; Reddy, K Mahendranadh; Reddy, G V K Mohan; Shastry, Y Mahadev

    2014-12-01

    The study was undertaken to evaluate the biaxial flexural strength, biaxial flexural strength after etching with 9 % HF acid and fracture toughness of three commonly used pressable all ceramic core materials. Ninety glass ceramic specimens were fabricated from three commercially available leucite based core ceramic material (1) Esthetic Empress, (2) Cergo, and (3) Performance Plus. Thirty discs of each material were divided into three groups of 10 discs each. Biaxial flexural strength (30 discs,) Biaxial flexural strength for samples treated with 9 % HF acid (30 discs) and fracture toughness (30 discs) were evaluated. Core material Performance Plus had the lowest biaxial strength of 124.89 MPa, Cergo had strength of 152.22 MPa and the highest value of 163.95 was reported for Esthetic Empress. For samples treated 9 % HF, Performance Plus had the lowest biaxial strength of 98.37 MPa, Cergo had strength of 117.42 MPa and the highest value of 143.74 was reported for Esthetic Empress. Core material Performance Plus had the lowest fracture toughness of 1.063 MPa, Cergo had strength of 1.112 MPa and the highest value of 1.225 was reported for Esthetic Empress. The results shows that Esthetic Empress had better mechanical properties compared to Cergo had Performance Plus in relation to the parameters tested.

  8. Long-Term Flexural Behaviors of GFRP Reinforced Concrete Beams Exposed to Accelerated Aging Exposure Conditions

    Directory of Open Access Journals (Sweden)

    Yeonho Park

    2014-06-01

    Full Text Available This study investigates the impact of accelerated aging conditions on the long-term flexural behavior and ductility of reinforced concrete (RC members with glass fiber-reinforced polymer (GFRP bars (RC-GFRP specimen and steel bars (RC-steel specimen. A total of thirty six specimens were designed with different amounts of reinforcement with three types of reinforcing bars (i.e., helically wrapped GFRP, sand-coated surface GFRP and steel. Eighteen specimens were subjected to sustained loads and accelerated aging conditions (i.e., 47 °C and 80% relative humidity in a chamber. The flexural behavior of specimens under 300-day exposure was compared to that of the companion specimens without experiencing accelerated aging conditions. Results indicate that the accelerated aging conditions reduced flexural capacity in not only RC-steel, but also RC-GFRP specimens, with different rates of reduction. Different types of GFRP reinforcement exhibited different rates of degradation of the flexural capacity when embedded in concrete under the same exposure conditions. Several existing models were compared with experimental results for predicting the deflection and deformability index for specimens. Bischoff and Gross’s model exhibited an excellent prediction of the time-dependent deflections. Except for the deformability index proposed by Jaeger, there was no general trend related to the aging duration. This study recommends the need for further investigation on the prediction of the deformability index.

  9. Compressive and flexural strength of expanded perlite aggregate mortar subjected to high temperatures

    Science.gov (United States)

    Zulkifeli, Muhamad Faqrul Hisham bin Mohd; Saman@Hj Mohamed, Hamidah binti Mohd

    2017-08-01

    Work on thermal resistant of outer structures of buildings is one of the solution to reduce death, damages and properties loss in fire cases. Structures protected with thermal resistant materials can delay or avoid failure and collapse during fire. Hence, establishment of skin cladding with advance materials to protect the structure of buildings is a necessary action. Expanded perlite is a good insulation material which can be used as aggregate replacement in mortar. This study is to study on mortar mechanical properties of flexural and compressive strength subjected to elevated temperatures using expanded perlite aggregate (EPA). This study involved experimental work which was developing mortar with sand replacement by volume of 0%, 10%, 20%, 30% and 40% of EPA and cured for 56 days. The mortars then exposed to 200°C, 400 °C, 700 °C and 1000 °C. Flexural and compressive strength of the mortar were tested. The tests showed that there were increased of flexural and compressive strength at 200°C, and constantly decreased when subjected to 400°C, 700°C and 1000 °C. There were also variation of strengths at different percentages of EPA replacement. Highest compressive strength and flexural strength recorded were both at 200 °C with 65.52 MPa and 21.34 MPa respectively. The study conclude that by using EPA as aggregate replacement was ineffective below elevated temperatures but increased the performance of the mortar at elevated temperatures.

  10. Flexural fatigue failures and lives of Eco-Core sandwich beams

    International Nuclear Information System (INIS)

    Hossain, Mohammad Mynul; Shivakumar, Kunigal

    2014-01-01

    Highlights: • Eco-Core sandwich beam is flexural fatigue tested to study its fatigue response. • The core showed three failure types: damage onset, progression and final failure. • These failures were found to be represented by 1%, 5% and 7% change in compliance. • The fatigue stress-life (S–N) relationship follows a power low, σ max /σ ct = A o N α . • The fatigue failure was by multiple vertical cracks followed by 45° shear failure. - Abstract: Eco-Core is a class of syntactic foam made from small volume of high char yield binder and large volume of a class of flyash for fire resistance application. Very little or no flexural fatigue data of this class of core material is reported in the open literature. This paper presents a flexural fatigue response of Eco-Core in a glass/vinyl ester composite face sheet sandwich beam. A four-point loaded flexural test specimen was designed and tested in static and fatigue loadings to cause tension failure in the core. The fatigue test was conducted at maximum cyclic stress (σ max ) ranged from 0.7σ ct to 0.9σ ct , where σ ct is the static flexural strength of the core. The sinusoidal loading frequency of 2 Hz with the stress ratio of 0.1 was used. Flexural fatigue failure modes of Eco-Core sandwich beam were classified: damage onset (single tension crack), damage progression (multiple tension cracks) and ultimate failure (a combination of tension and shear). These failures were characterized by 1%, 5% and 7% changes in compliance that corresponds to N 1% , N 5% and N 7% lives. The fatigue stress-life (S–N) relationship was found to follow the well-known power law equation, σ max /σ ct = A o N α . The constants A o and α were established for all three types of failures. The endurance limit was established based on 1 million cycles limit and it was found to be 0.65σ ct , 0.70σ ct and 0.71σ ct , respectively for the three modes of failure. Flexural fatigue and static failure modes of Eco-Core sandwich

  11. Regulated necrosis and its implications in toxicology.

    Science.gov (United States)

    Aki, Toshihiko; Funakoshi, Takeshi; Uemura, Koichi

    2015-07-03

    Recent research developments have revealed that caspase-dependent apoptosis is not the sole form of regulated cell death. Caspase-independent, but genetically regulated, forms of cell death include pyroptosis, necroptosis, parthanatos, and the recently discovered ferroptosis and autosis. Importantly, regulated necrosis can be modulated by small molecule inhibitors/activators, confirming the cell autonomous mechanism of these forms of cell death. The success of small molecule-mediated manipulation of regulated necrosis has produced great changes in the field of cell death research, and has also brought about significant changes in the fields of pharmacology as well as toxicology. In this review, we intend to summarize the modes of regulated cell death other than apoptosis, and discuss their implications in toxicology. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. Avascular necrosis of bone complicating corticosteroid replacement therapy.

    OpenAIRE

    Williams, P L; Corbett, M

    1983-01-01

    Two patients who developed widespread severe avascular necrosis of bone while on steroid replacement therapy are described. One, a diabetic, underwent yttrium-90 pituitary ablation for retinopathy and developed avascular necrosis within 18 months of starting prednisolone. The other, who had Addison's disease, developed avascular necrosis within 14 months of starting cortisol replacement therapy. Both cases came to bilateral total hip replacement.

  13. Rin4 Causes Hybrid Necrosis and Race-Specific Resistance in an Interspecific Lettuce Hybrid

    NARCIS (Netherlands)

    Jeuken, M.J.W.; Zhang, N.; McHale, L.K.; Pelgrom, K.T.B.; Boer, den E.; Lindhout, P.; Michelmore, R.; Visser, R.G.F.; Niks, R.E.

    2009-01-01

    Some inter- and intraspecific crosses may result in reduced viability or sterility in the offspring, often due to genetic incompatibilities resulting from interactions between two or more loci. Hybrid necrosis is a postzygotic genetic incompatibility that is phenotypically manifested as necrotic

  14. Severe glandular tularemia in a patient treated with anti-tumour necrosis factor for psoriatic arthritis

    Directory of Open Access Journals (Sweden)

    Ruxandra Calin

    2017-07-01

    Full Text Available A case of severe glandular tularemia in a patient receiving anti-tumour necrosis factor (TNF therapy is reported here. The patient required prolonged treatment with doxycycline–ciprofloxacin due to early relapse after ciprofloxacin was stopped. Tularemia may have a more severe course in patients receiving anti-TNF. This may thus be an indication for more aggressive treatment.

  15. Nilotinib induced avascular necrosis of femoral head in an adult chronic myeloid leukemia patient.

    Science.gov (United States)

    Thekkudan, Shinto Francis; Nityanand, Soniya

    2018-06-01

    We report a rare case of avascular necrosis of femoral head (AVNFH) in an adult chronic myeloid leukemia - chronic phase (CML-CP) patient during due course of therapy with second line Tyrosine Kinase Inhibitor (TKI), Nilotinib. A high index of clinical suspicion should be kept in any symptomatic CML patient on TKI's.

  16. Integrated management of sunflower necrosis disease

    OpenAIRE

    Shirshikar S.P.

    2008-01-01

    Sunflower necrosis disease (SND) is a new threat for sunflower cultivation in India. The disease was observed during 1997 in Karnataka, a major sunflower growing state of India. Later, its occurrence was reported from almost all sunflower growing states of India, posing threat to sunflower cultivation. Presently no reliable resistant sources are available. The disease being viral in nature is very much difficult to combat by single approach. At Oilseeds Research Station, Latur (M.S.), India, ...

  17. Maxillary Necrosis: A Sequelae of Fungal Osteomyelitis

    Directory of Open Access Journals (Sweden)

    K Anbarasi

    2010-01-01

    Full Text Available Osteomyelitis is designated to a variety of bone diseases having inflammation as a common denominator. Persistent infection progresses to inflammation of marrow space, haversian system and periostium of affected region. Thrombosis of endothelial vessels cause necrosis and sequestrum formation. Both pyogenic and nonpyogenic infections of jaw lead to this condition. Immunosuppressed patients are more prone to mycelial infections, whereas their occurrence in immunocompetent individuals are highly unusual.

  18. [Avascular necrosis of the femoral head].

    Science.gov (United States)

    Porubský, Peter; Trč, Tomáš; Havlas, Vojtěch; Smetana, Pavel

    Avascular necrosis of the femoral head in adults is not common, but not too rare diseases. In orthopedic practice, it is one of the diseases that are causing implantation of hip replacement at a relatively early age. In the early detection and initiation of therapy can delay the implantation of prosthesis for several years, which is certainly more convenient for the patient and beneficial. This article is intended to acquaint the reader with the basic diagnostic procedures and therapy.

  19. Paraneoplastic digital necrosis associated with rectum carcinoma

    Directory of Open Access Journals (Sweden)

    Ali Alkan

    2015-12-01

    Full Text Available Paraneoplastic vascular pathologies are rare in daily practice. There is limited data about this phenomenon. Patient with a diagnosis of metastatic rectum carcinoma presented with digital necrosis. The work up for vascular and rheumatological pathology was inconclusive. Lesions progressively improved with steroid therapy. Paraneoplastic vascular lesions are rare in oncology practice. Our case points out important parts of a rare clinical entity. J Clin Exp Invest 2015; 6 (4: 391-392

  20. Sol-gel derived bioactive coating on zirconia: Effect on flexural strength and cell proliferation.

    Science.gov (United States)

    Shahramian, Khalil; Leminen, Heidi; Meretoja, Ville; Linderbäck, Paula; Kangasniemi, Ilkka; Lassila, Lippo; Abdulmajeed, Aous; Närhi, Timo

    2017-11-01

    The purpose of this study was to evaluate the effect of sol-gel derived bioactive coatings on the biaxial flexural strength and fibroblast proliferation of zirconia, aimed to be used as an implant abutment material. Yttrium stabilized zirconia disc-shaped specimens were cut, ground, sintered, and finally cleansed ultrasonically in each of acetone and ethanol for 5 minutes. Three experimental groups (n = 15) were fabricated, zirconia with sol-gel derived titania (TiO 2 ) coating, zirconia with sol-gel derived zirconia (ZrO 2 ) coating, and non-coated zirconia as a control. The surfaces of the specimens were analyzed through images taken using a scanning electron microscope (SEM), and a non-contact tapping mode atomic force microscope (AFM) was used to record the surface topography and roughness of the coated specimens. Biaxial flexural strength values were determined using the piston-on-three ball technique. Human gingival fibroblast proliferation on the surface of the specimens was evaluated using AlamarBlue assay™. Data were analyzed using a one-way analysis of variance (ANOVA) followed by Tukey's post-hoc test. Additionally, the biaxial flexural strength data was also statistically analyzed with the Weibull distribution. The biaxial flexural strength of zirconia specimens was unaffected (p > 0.05). Weibull modulus of TiO 2 coated and ZrO 2 coated groups (5.7 and 5.4, respectively) were lower than the control (8.0). Specimens coated with ZrO 2 showed significantly lower fibroblast proliferation compared to other groups (p sol-gel derived coatings have no influence on the flexural strength of zirconia. ZrO 2 coated specimens showed significantly lower cell proliferation after 12 days than TiO 2 coated or non-coated control. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2401-2407, 2017. © 2016 Wiley Periodicals, Inc.

  1. Influence of thermal cycling on flexural properties of composites reinforced with unidirectional silica-glass fibers.

    Science.gov (United States)

    Meriç, Gökçe; Ruyter, I Eystein

    2008-08-01

    The purpose was to investigate the effect of water storage and thermal cycling on the flexural properties of differently sized unidirectional fiber-reinforced composites (FRCs) containing different quantities of fibers. The effect of fiber orientation on the thermal expansion of FRCs as well as how the stresses in the composites can be affected was considered. An experimental polymeric base material was reinforced with silica-glass fibers. The cleaned and silanized fibers were sized with either linear PBMA-size or crosslinked PMMA-size. For the determination of flexural properties and water uptake, specimens were processed with various quantities of differently sized unidirectional fibers. Water uptake of FRC was measured. Water immersed specimens were thermally cycled for 500 and 12,000 cycles (5 degrees C/55 degrees C). Flexural properties of "dry" and wet specimens with and without thermal cycling were determined by a three-point bending test. The linear coefficients of thermal expansion (LCTE) for FRC samples with different fiber orientations were determined using a thermomechanical analyzer. Water uptake of the FRC specimens increased with a decrease in fiber content of the FRC. Flexural properties of FRCs improved with increasing fiber content, whereas the flexural properties were not influenced significantly by water and thermal cycling. Fiber orientation had different effects on LCTE of FRCs. Unidirectional FRCs had two different LCTE in longitudinal and transverse directions whereas bidirectional FRCs had similar LCTE in two directions and a higher one in the third direction. The results of the study suggest that the surface-treated unidirectional silica-glass FRC can be used for long-term clinical applications in the oral cavity.

  2. Cuspal Flexure and Extent of Cure of a Bulk-fill Flowable Base Composite.

    Science.gov (United States)

    Francis, A V; Braxton, A D; Ahmad, W; Tantbirojn, D; Simon, J F; Versluis, A

    2015-01-01

    To investigate a bulk-fill flowable base composite (Surefil SDR Flow) in terms of cuspal flexure and cure when used in incremental or bulk techniques. Mesio-occluso-distal cavities (4 mm deep, 4 mm wide) were prepared in 24 extracted molars. The slot-shaped cavities were etched, bonded, and restored in 1) two 2-mm increments Esthet-X HD (control), 2) two 2-mm increments Surefil SDR Flow, or 3) 4-mm bulk Surefil SDR Flow (N=8). The teeth were digitized after preparation (baseline) and restoration and were precisely aligned to calculate cuspal flexure. Restored teeth were placed in fuchsin dye for 16 hours to determine occlusal bond integrity from dye penetration. Extent of cure was assessed by hardness at 0.5-mm increments through the restoration depth. Results were analyzed with analysis of variance and Student-Newman-Keuls post hoc tests (α=0.05). Surefil SDR Flow, either incrementally or bulk filled, demonstrated significantly less cuspal flexure than Esthet-X HD. Dye penetration was less than 3% of cavity wall height and was not statistically different among groups. The hardness of Surefil SDR Flow did not change throughout the depth for both incrementally and bulk filled restorations; the hardness of Esthet-X HD was statistically significantly lower at the bottom of each increment than at the top. Filling in bulk or increments made no significant difference in marginal bond quality or cuspal flexure for the bulk-fill composite. However, the bulk-fill composite caused less cuspal flexure than the incrementally placed conventional composite. The bulk-fill composite cured all the way through (4 mm), whereas the conventional composite had lower cure at the bottom of each increment.

  3. Flexural strength and the probability of failure of cold isostatic pressed zirconia core ceramics.

    Science.gov (United States)

    Siarampi, Eleni; Kontonasaki, Eleana; Papadopoulou, Lambrini; Kantiranis, Nikolaos; Zorba, Triantafillia; Paraskevopoulos, Konstantinos M; Koidis, Petros

    2012-08-01

    The flexural strength of zirconia core ceramics must predictably withstand the high stresses developed during oral function. The in-depth interpretation of strength parameters and the probability of failure during clinical performance could assist the clinician in selecting the optimum materials while planning treatment. The purpose of this study was to evaluate the flexural strength based on survival probability and Weibull statistical analysis of 2 zirconia cores for ceramic restorations. Twenty bar-shaped specimens were milled from 2 core ceramics, IPS e.max ZirCAD and Wieland ZENO Zr, and were loaded until fracture according to ISO 6872 (3-point bending test). An independent samples t test was used to assess significant differences of fracture strength (α=.05). Weibull statistical analysis of the flexural strength data provided 2 parameter estimates: Weibull modulus (m) and characteristic strength (σ(0)). The fractured surfaces of the specimens were evaluated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The investigation of the crystallographic state of the materials was performed with x-ray diffraction analysis (XRD) and Fourier transform infrared (FTIR) spectroscopy. Higher mean flexural strength (Plines zones). Both groups primarily sustained the tetragonal phase of zirconia and a negligible amount of the monoclinic phase. Although both zirconia ceramics presented similar fractographic and crystallographic properties, the higher flexural strength of WZ ceramics was associated with a lower m and more voids in their microstructure. These findings suggest a greater scattering of strength values and a flaw distribution that are expected to increase failure probability. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  4. Comparison of different grinding procedures on the flexural strength of zirconia.

    Science.gov (United States)

    Işeri, Ufuk; Ozkurt, Zeynep; Yalnız, Ayşe; Kazazoğlu, Ender

    2012-05-01

    The surface of zirconia ceramic is damaged during grinding, which may affect the mechanical properties of the material. The purpose of this study was to compare the biaxial flexural strength of zirconia after different grinding procedures and to measure the temperature rise from grinding. Forty disk-shaped zirconia specimens (15 × 1.2 mm) with a smaller disk in the center of each disk (1 × 3 mm) were divided into 4 groups (n=10). The specimens were ground with a high-speed handpiece and micromotor with 2 different grinding protocols, continual grinding and periodic grinding (10 seconds grinding with 10 seconds duration), until the smaller disk was removed. Control specimens without the center disk (n=10) were analyzed without grinding. The biaxial flexural strengths of the disks were determined in a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture strength (MPa) was recorded, and the results were analyzed using a 1-way ANOVA, Tukey HSD test, Student's t test, and Pearson correlation test (α=05). All grinding procedures significantly decreased flexural strength (Pmicromotor groups (718 MPa). The temperature values obtained from micromotor grinding (127°C) were significantly higher than those from high-speed handpiece grinding (63°C) (P<.01). Grinding zirconia decreased flexural strength. Zirconia material ground with a high-speed handpiece run continually caused the least reduction in flexural strength. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  5. Flexural behavior and design of steel-plate composite (SC) walls for accident thermal loading

    Energy Technology Data Exchange (ETDEWEB)

    Booth, Peter N., E-mail: boothpn@purdue.edu [Lyles School of Civil Engineering, Purdue University, West Lafayette, IN (United States); Varma, Amit H., E-mail: ahvarma@purdue.edu [Lyles School of Civil Engineering, Purdue University, West Lafayette, IN (United States); Sener, Kadir C., E-mail: ksener@purdue.edu [Lyles School of Civil Engineering, Purdue University, West Lafayette, IN (United States); Malushte, Sanjeev R. [Bechtel Corp., Frederick, MD (United States)

    2015-12-15

    Modular steel-plate composite (SC) safety-related nuclear power plant structures must be designed to resist accident thermal and mechanical loads. The design accident thermal load represents the condition where high pressure and temperature steam is released as result of a mechanical failure and applied against the surfaces of power plant structural walls. The effect of heating and pressure can have both short and long term effects on the mechanical integrity of SC structures including degradation and cracking of concrete infill, residual stresses, and out-of-plane deformations. The purpose of this research is to study the effects of thermal and mechanical loads on the out-of-plane flexural response of SC walls and to develop simplified equations that can be used to predict behavior. Four experimental beam tests are reported that represent full-scale cross-sections of SC walls subjected to combinations of mechanical and thermal loads. The study determined that thermal loads reduce the out-of-plane flexural stiffness of SC walls. For the ambient condition, the flexural stiffness closely matches a conventional elastic cracked-transformed model, and at elevated temperatures, the stiffness is reduced to a fully-cracked flexural stiffness that only takes into account the stiffness of the steel faceplates. A method is presented for estimating the thermal curvature, ϕ{sub th}, and thermal moment, M{sub th}, resulting from unequal heating of opposing faces of an SC wall. Based on the tests in this study, the application of accident thermal loads did not result in a reduction of the flexural strength of the SC section.

  6. The effect of veneering and heat treatment on the flexural strength of Empress 2 ceramics.

    Science.gov (United States)

    Cattell, M J; Palumbo, R P; Knowles, J C; Clarke, R L; Samarawickrama, D Y D

    2002-05-01

    The aims of the study were to test and compare the biaxial flexural strength and reliability of Empress 2 ceramics after heat treatment and the addition of the veneering material and to characterise their microstructures. Forty disc specimens (2 x 14 mm) and forty disc specimens (1 x 14 mm) were produced by heat pressing in the EP 500 press furnace. Group 1 (2 x 14 mm Empress 2 core) was as heat pressed and group 2 (2 x 14 mm Empress 2 core) was subjected to the recommended firing cycles. Groups 3 and 4 (1 x 14 mm Empress 2 core) were veneered with the dentine material and heat-treated as per group 2. Groups 1, 2 and 3 were lapped to 800 grit silicon carbide paper on the compressive surface only and group 4 on both the compressive and tensile test surfaces. Twenty disc specimens per group were tested using the biaxial flexure test at a crosshead speed of 0.15 mm/min. Specimens were characterised using X-ray diffraction (XRD) and secondary electron imaging (SEM). Mean biaxial flexural strengths (MPa+/-SD) were group 1: 265.5+/-25.7; group 2: 251.3+/-30.2; group 3: 258.6+/-21.4 and group 4: 308.6+/-37.7. There was no statistical difference between groups 1, 2 and 3 (p>0.05), but differences for group 4 (pEmpress 2 core material and an amorphous glass and some evidence of a crystalline phase in the dentine material. CONCLUSIONS; Veneering or heat treatment of Empress 2 ceramics did not significantly affect the mean biaxial flexural strength (p>0.05) or reliability. Surface modification of the Empress 2 core material increased the mean biaxial flexural strength (p<0.05).

  7. Edge chipping resistance and flexural strength of polymer infiltrated ceramic network and resin nanoceramic restorative materials.

    Science.gov (United States)

    Argyrou, Renos; Thompson, Geoffrey A; Cho, Seok-Hwan; Berzins, David W

    2016-09-01

    Two novel restorative materials, a polymer infiltrated ceramic network (PICN) and a resin nanoceramic (RNC), for computer-assisted design and computer-assisted manufacturing (CAD-CAM) applications have recently become commercially available. Little independent evidence regarding their mechanical properties exists to facilitate material selection. The purpose of this in vitro study was to measure the edge chipping resistance and flexural strength of the PICN and RNC materials and compare them with 2 commonly used feldspathic ceramic (FC) and leucite reinforced glass-ceramic (LRGC) CAD-CAM materials that share the same clinical indications. PICN, RNC, FC, and LRGC material specimens were obtained by sectioning commercially available CAD-CAM blocks. Edge chipping test specimens (n=20/material) were adhesively attached to a resin substrate before testing. Edge chips were produced using a 120-degree, sharp, conical diamond indenter mounted on a universal testing machine and positioned 0.1 to 0.7 mm horizontally from the specimen's edge. The chipping force was plotted against distance to the edge, and the data were fitted to linear and quadratic equations. One-way ANOVA determined intergroup differences (α=.05) in edge chipping toughness. Beam specimens (n=22/material) were tested for determining flexural strength using a 3-point bend test. Weibull statistics determined intergroup differences (α=.05). Flexural modulus and work of fracture were also calculated, and 1-way ANOVA determined intergroup differences (α=.05) RESULTS: Significant (Pmaterials for the 4 mechanical properties. Specifically, the material rankings were edge chipping toughness: RNC>LRGC=FC>PICN; flexural strength: RNC=LRGC>PICN>FC; flexural modulus: RNCLRGC=PICN>FC. The RNC material demonstrated superior performance for the mechanical properties tested compared with the other 3 materials. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All

  8. Bladder necrosis: 'A man without a bladder'.

    Science.gov (United States)

    Bosschieter, Judith; Oudshoorn, Frederik H K; Meuleman, Eric J H; Nieuwenhuijzen, Jakko A

    2018-02-17

    Since the use of antibiotics, bladder necrosis has become a rare condition. We report a case of bladder necrosis in a 90-year-old man following urinary retention. After insertion of a transurethral catheter (TUC), 2 L of urine was evacuated. In the following days, the TUC became intermittently blocked. Adequate bladder drainage could not be obtained despite intensive rinsing and placement of a suprapubic catheter. On surgical exploration necrosis of almost the entire bladder wall, except for the trigone, was encountered. Surgical debridement of the non-viable bladder wall without opening the abdominal cavity was conducted, and a TUC was placed in the Retzius cavity to ensure evacuation of urine. Since the patient was haemodynamically unstable, construction of a urinary diversion was waived and urinary drainage of the Retzius cavity by the TUC was accepted, resulting in adequate urinary drainage without compromising renal function. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  9. Partial avascular necrosis after talar neck fracture.

    Science.gov (United States)

    Babu, Nina; Schuberth, John M

    2010-09-01

    Recently, it has been shown that avascular necrosis of the talus can occur in only a portion of the talar body. There is little information regarding the geographic location of the avascular segment and the clinical significance of an incomplete avascular process. Seven patients with partial avascular necrosis after Hawkins type II or III fracture dislocations were evaluated with magnetic resonance scans. The precise anatomic location of the avascular segment was determined and assigned to a specific quadrant of the talar body. The operative exposure, incidence of collapse, and time to operative intervention was recorded. The avascular segment of the talar body was located predominantly in the anterior lateral and superior portion in six of the seven patients. Collapse occurred in three of the patients in the area of avascular process. There were no observable trends with regard to operative exposure, Hawkins classification, incidence of collapse, or time to operative intervention to the location of the avascular segment. Partial avascular necrosis can occur after fracture dislocation of the talus. The predominant location of the avascular segment was the anterior lateral and superior portion of the talar body. This observation corresponds to regional damage to the blood supply of the talus and may help clarify the pathogenesis of partial avascular process.

  10. Severe ischemic bowel necrosis caused by terlipressin during treatment of hepatorenal syndrome

    Directory of Open Access Journals (Sweden)

    Hae Rim Kim

    2013-12-01

    Full Text Available Terlipressin is a vasopressin analogue that is widely used in the treatment of hepatorenal syndrome or variceal bleeding. Because it acts mainly on splanchnic vessels, terlipressin has a lower incidence of severe ischemic complications than does vasopressin. However, it can still lead to serious complications such as myocardial infarction, skin necrosis, or bowel ischemia. Herein we report a case of severe ischemic bowel necrosis in a 46-year-old cirrhotic patient treated with terlipressin. Although the patient received bowel resection, death occurred due to ongoing hypotension and metabolic acidosis. Attention should be paid to patients complaining of abdominal pain during treatment with terlipressin.

  11. Avascular necrosis of the femoral head post heart-transplantation and steroid dosage.

    Science.gov (United States)

    Foley-Nolan, D; Daly, C; Barry, C; Woods, A; Neligan, M; Coughlan, R J

    1992-12-01

    Avascular necrosis (avn) post heart-transplantation has been considered to be due to the high doses of steroids used to immunosuppress these patients in attempting to prevent transplant rejection. This study shows that avascular necrosis occurs even when low dose steroids regimes are used and demonstrates no significant correlation between steroid dosage and the development of avn. Patients with symptomatic avn benefit from early diagnosis and management of their condition in that the need for total joint arthroplasty can be prevented in many cases.

  12. Aseptic necrosis in caisson workers: a new set of decompression tables.

    Science.gov (United States)

    Downs, G J; Kindwall, E P

    1986-06-01

    There is a high incidence of aseptic necrosis and decompression sickness among caisson workers due to inadequate decompression using the current OSHA decompression tables (1-7). Because of this, a new set of tables--Autodec III-O2--was developed which more effectively eliminates nitrogen from the body and, therefore, should decrease the incidence of both bends and aseptic necrosis. The Autodec III-O2 schedule's superiority was statistically significant at a level of 0.08 compared to the OSHA table. It is our conclusion that OSHA should adopt the Autodec III-O2 schedule as a replacement for the current decompression tables.

  13. Foot Skin Ischemic Necrosis following Heel Prick in a Newborn

    Directory of Open Access Journals (Sweden)

    Esad Koklu

    2013-01-01

    Full Text Available There are only a few reports on side effects after heel prick in neonates although heel prick has been performed all over the world for many years. The medicine staff had obtained only a drop of blood by pricking the baby’s heel using a lancet without compressing the heel or foot to measure his blood glucose level 3 hours after birth. However he developed a severe and hemorrhagic skin reaction on his entire left foot, beginning 30 minutes after obtaining the drop of blood by pricking the baby’s heel using a lancet. The lesion, which was treated with topical mupirocin and povidone-iodine solution daily, slowly decreased in size and had almost fully resolved within 3 weeks. He was healthy and 9 months old at the time of writing this paper. We herein report a case of foot skin ischemic necrosis following heel prick in a newborn. To our knowledge this patient is the first case of foot skin ischemic necrosis due to heel prick in newborns.

  14. Delayed radiation necrosis 7 years after gamma knife surgery for arteriovenous malformation. Two case reports

    International Nuclear Information System (INIS)

    Oyoshi, Tatsuki; Yatsushiro, Kazutaka; Arita, Kazunori; Hirahara, Kazuho; Uetsuhara, Koichi

    2010-01-01

    A 44-year-old woman and a 55-year-old woman were treated with gamma knife surgery (GKS) for occipital arteriovenous malformation (AVM). Angiography confirmed complete nidus obliterations 2 years after GKS. However, both patients complained of chronic headache and visual symptoms from around 7 years after GKS. Magnetic resonance imaging showed round masses with or without cystic change surrounded by large areas of brain edema. Angiography also showed complete obliteration of AVM at this time. Extended corticosteroid treatment failed to control the edema. Both patients underwent total surgical removal of the mass. Visual disturbance and chronic headache improved postoperatively and the brain edema rapidly subsided. The histological diagnosis was radiation necrosis in both cases, attributed to the low conformity index and large 12-Gy volume due to usage of a large collimator for GKS. These cases of delayed radiation necrosis after GKS suggest that surgical removal of necrotic lesions is necessary for radiation necrosis intractable to medical treatment. (author)

  15. Jejunal Replacement of Stomach in Two Children with Total Gastric Necrosis

    Directory of Open Access Journals (Sweden)

    Onder Ozden

    2014-04-01

    Full Text Available Total gastrectomy is an extremely rare procedure in children and experience with its replacement is very limited. We present two patients who had jejunal replacement due to total gastric necrosis. The first patient was a- 2-year-old boy who admitted with a history of caustic ingestion. He was taken operation because of gastric perforation and necrosis. Anastomosis was applied by using jejunal segments. The second patient was an 11-years-old girl who left diaphragmatic hernia and acute gastric volvulus. At laparotomy, Total gastrectomy and Hunt-Lawrence type gastroesophostomy were made. Reconstruction with jejunum is thought as a good option in total gastric necrosis according to our 2 patient experiences. [Cukurova Med J 2014; 39(2.000: 403-407

  16. Muscle necrosis in the extremities: evaluation with Tc-99m pyrophosphate scanning--a retrospective review

    International Nuclear Information System (INIS)

    Timmons, J.H.; Hartshorne, M.F.; Peters, V.J.; Cawthon, M.A.; Bauman, J.M.

    1988-01-01

    A retrospective review was done of 34 extremities studied between 1981 and 1985 with technetium-99m pyrophosphate scanning; 22 were subsequently amputated. Results of detailed pathologic examination or immediate postoperative examination of the resected extremity were available in 16 cases. In these cases, scanning had allowed correct prediction of the level of amputation and of the specific areas of muscle infarction in 13 cases. In the one case in which amputation was performed for infection rather than muscle necrosis, the lack of necrosis was correctly predicted with the scan. The limited results of this study indicate that the Tc-99m pyrophosphate scan allows the location of necrotic muscle to be predicted accurately and may therefore be a useful adjunct in determining the best level for ultimate amputation. Special caution is required in those cases in which muscle necrosis is due to acute causes (e.g., traumatic thrombosis) rather than chronic vascular disease

  17. Avascular necrosis of the femoral head at 2 years after pertrochanteric fracture surgery: Case report.

    Science.gov (United States)

    Deleanu, Bogdan; Prejbeanu, Radu; Vermesan, Dinu; Honcea, Lucian; Mioc, Mihail Lazar; Tsiridis, Eleftherios; Predescu, Vlad

    2016-02-01

    The avascular necrosis of the femoral head represents the death of bone tissue due to the lack of blood supply. The disease has a progressive evolution and left untreated leads to femoral head collapse and severe arthritis. We present a case of a pertrochanteric fracture which has been successfully operated with a dynamic interlocking trochanteric gamma nail on the right hip. At 2 years after surgery the patient developed an incipient avascular necrosis of the femoral head. Despite the good positioning of the implant, we considered that the source of the pain was an intolerance of the implant, and thus we removed it. After implant removal, the patient was kept under observation and conservative treatment, to prevent further damage to the right hip and allow the healing to occur. At 6 months after the gamma nail was removed the X-rays revealed advanced avascular necrosis of the femoral head and secondary osteoarthritis on the right hip. The patient underwent surgery with an uncemented total hip arthroplasty. There are a few discussions regarding the avascular necrosis of the femoral head. These discussions may include the predisposing risk factors, the treatment of choice and the postoperative complications. The avascular necrosis of the femoral head is a complication of pertrochanteric fractures that can not be foreseen or avoided. The optimal treatment in these cases is uncemented total hip arthroplasty.

  18. [Necrosis in fingers and toes following local anaesthesia with adrenaline--an urban legend?].

    Science.gov (United States)

    Finsen, Vilhjalmur

    2013-09-17

    It is often maintained that a local anaesthetic (usually lidocaine) with adrenaline must not be used in fingers and toes because it may cause necrosis due to vascular spasm in end arteries. This review article is an attempt to find evidence to support this warning. Relevant literature was found by means of searches in PubMed limited downwards to 1946 and in EMBASE from 1980 to 2012, and in reference lists. Five review articles on finger necrosis following local anaesthesia concluded that lidocaine with adrenaline does not entail a risk of ischaemic injury. One article found 48 reported cases of finger necrosis in the period 1880 to 2000. Most were from the first half of the 1900s, and none involved lidocaine. Gangrene of part of the finger tip has subsequently been described in one patient with Raynaud's syndrome. No cases of necrosis have been described in a large number of reported accidents in which EpiPen injections contained the same quantity of adrenaline as is found in 60 ml lidocaine with adrenaline. Over a quarter of a million reports have been made of operations on feet, hands, fingers and toes anaesthetised with lidocaine with adrenaline without resulting necrosis. There are no grounds for the warning against using lidocaine with adrenaline in fingers and toes. This anaesthetic offers considerable practical advantages. Care should be taken with infected fingers or fingers with poor circulation.

  19. Ketoconazole attenuates radiation-induction of tumor necrosis factor

    Energy Technology Data Exchange (ETDEWEB)

    Hallahan, D.E.; Virudachalam, S.; Kufe, D.W.; Weichselbaum, R.R. [Dana Farber Cancer Institute, Boston, MA (United States)

    1994-07-01

    Previous work has demonstrated that inhibitors of phospholipase A2 attenuate ionizing radiation-induced arachidonic acid production, protein kinase C activation, and prevent subsequent induction of the tumor necrosis factor gene. Because arachidonic acid contributes to radiation-induced tumor necrosis factor expression, the authors analyzed the effects of agents which alter arachidonate metabolism on the regulation of this gene. Phospholipase A2 inhibitors quinicrine, bromphenyl bromide, and pentoxyfylline or the inhibitor of lipoxygenase (ketoconazole) or the inhibitor of cycloxygenase (indomethacine) were added to cell culture 1 h prior to irradiation. Radiation-induced tumor necrosis factor gene expression was attenuated by each of the phospholipase A2 inhibitors (quinicrine, bromphenylbromide, and pentoxyfylline). Furthermore, ketoconazole attenuated X ray induced tumor necrosis factor gene expression. Conversely, indomethacin enhanced tumor necrosis factor expression following irradiation. The finding that radiation-induced tumor necrosis factor gene expression was attenuated by ketoconazole suggests that the lipoxygenase pathway participates in signal transduction preceding tumor necrosis factor induction. Enhancement of tumor necrosis factor expression by indomethacin following irradiation suggests that prostaglandins produced by cyclooxygenase act as negative regulators of tumor necrosis factor expression. Inhibitors of tumor necrosis factor induction ameliorate acute and subacute sequelae of radiotherapy. The authors propose therefore, that ketoconazole may reduce acute radiation sequelae such as mucositis and esophagitis through a reduction in tumor necrosis factor induction or inhibition of phospholipase A2 in addition to its antifungal activity. 25 refs., 2 figs.

  20. MRI study of avascular necrosis of the knee

    Energy Technology Data Exchange (ETDEWEB)

    Simizu, Koh; Suguro, Toru; Tsuchiya, Akihiro; Moriya, Hideshige; Nishikawa, Satoru; Arimizu, Noboru [Chiba Univ. (Japan). School of Medicine

    1990-10-01

    Magnetic resonance (MR) images of 70 joints were reviewed in 38 patients with avascular necrosis of the knee or hip joint, whose ages ranged from 19 to 62 years with an average of 41 years. According to causes, steroid induced avascular necrosis was the commonest, accounting for 87% of cases. The remainer of the cases were alcoholic avascular necrosis (8%) and idiopathic avascular necrosis (5%). Steroid induced avascular necrosis was greatly different from idiopathic avascular necrosis in view of clinical manifestations, common sites, and complications of femur head necrosis. Idiopathic avascular necrosis was common in the central part of internal condyle and was confined to one joint. Steroid induced avascular necrosis was common in the posterior part of external condyle and was frequently associated with multiple necroses of the diaphysis. Seventy five percent of the cases were associated with avascular necrosis of the knee. The diagnostic accuracy of the other imaging modalities in avascular necrosis was low (33% for plain roentgenography and 50% for RI examination). Thus, MR was the imaging procedure of choice for detecting avascular necrotic lesions. (N.K.).

  1. MRI study of avascular necrosis of the knee

    International Nuclear Information System (INIS)

    Simizu, Koh; Suguro, Toru; Tsuchiya, Akihiro; Moriya, Hideshige; Nishikawa, Satoru; Arimizu, Noboru

    1990-01-01

    Magnetic resonance (MR) images of 70 joints were reviewed in 38 patients with avascular necrosis of the knee or hip joint, whose ages ranged from 19 to 62 years with an average of 41 years. According to causes, steroid induced avascular necrosis was the commonest, accounting for 87% of cases. The remainer of the cases were alcoholic avascular necrosis (8%) and idiopathic avascular necrosis (5%). Steroid induced avascular necrosis was greatly different from idiopathic avascular necrosis in view of clinical manifestations, common sites, and complications of femur head necrosis. Idiopathic avascular necrosis was common in the central part of internal condyle and was confined to one joint. Steroid induced avascular necrosis was common in the posterior part of external condyle and was frequently associated with multiple necroses of the diaphysis. Seventy five percent of the cases were associated with avascular necrosis of the knee. The diagnostic accuracy of the other imaging modalities in avascular necrosis was low (33% for plain roentgenography and 50% for RI examination). Thus, MR was the imaging procedure of choice for detecting avascular necrotic lesions. (N.K.)

  2. Influence of fiber length on flexural and impact properties of Zalacca Midrib fiber/HDPE by compression molding

    Science.gov (United States)

    Pamungkas, Agil Fitri; Ariawan, Dody; Surojo, Eko; Triyono, Joko

    2018-02-01

    The aim of the research is to investigate the effect of fiber length on the flexural and impact properties of the composite of Zalacca Midrib Fiber (ZMF)/HDPE. The process of making composite was using compression molding method. The variation of fiber length were 1 mm, 3 mm, 5 mm, 7 mm and 9 mm, at 30% fiber volume fraction. The flexural and impact test according to ASTM D790 and ASTM D5941, respectively. Observing fracture surface was examained by using Scanning Electron Microscopy (SEM). The results showed that the flexural and impact strengths would be increase with the increase of fiber length.

  3. Functions of fish skin: flexural stiffness and steady swimming of longnose gar, Lepisosteus osseus

    Science.gov (United States)

    Long; Hale; Mchenry; Westneat

    1996-01-01

    The functions of fish skin during swimming remain enigmatic. Does skin stiffen the body and alter the propagation of the axial undulatory wave? To address this question, we measured the skin's in situ flexural stiffness and in vivo mechanical role in the longnose gar Lepisosteus osseus. To measure flexural stiffness, dead gar were gripped and bent in a device that measured applied bending moment (N m) and the resulting midline curvature (m-1). From these values, the flexural stiffness of the body (EI in N m2) was calculated before and after sequential alterations of skin structure. Cutting of the dermis between two caudal scale rows significantly reduced the flexural stiffness of the body and increased the neutral zone of curvature, a region of bending without detectable stiffness. Neither bending property was significantly altered by the removal of a caudal scale row. These alterations in skin structure were also made in live gar and the kinematics of steady swimming was measured before and after each treatment. Cutting of the dermis between two caudal scale rows, performed under anesthesia, changed the swimming kinematics of the fish: tailbeat frequency (Hz) and propulsive wave speed (body lengths per second, L s-1) decreased, while the depth (in L) of the trailing edge of the tail increased. The decreases in tailbeat frequency and wave speed are consistent with predictions of the theory of forced, harmonic vibrations; wave speed, if equated with resonance frequency, is proportional to the square root of a structure's stiffness. While it did not significantly reduce the body's flexural stiffness, surgical removal of a caudal scale row resulted in increased tailbeat amplitude and the relative total hydrodynamic power. In an attempt to understand the specific function of the scale row, we propose a model in which a scale row resists medio-lateral force applied by a single myomere, thus functioning to enhance mechanical advantage for bending. Finally, surgical

  4. Comparative Evaluation of Flexural Strength of Provisional Crown and Bridge Materials-An Invitro Study.

    Science.gov (United States)

    Singh, Ankita; Garg, Sandeep

    2016-08-01

    Provisional restorations serve a key role as a functional and esthetic try-in for the design of the final prosthesis. During selection of materials for this restoration, clinicians must consider physical properties, ease of handling, cost and patient satisfaction and approval. To evaluate and compare the flexural strength of provisional crown and bridge materials available commercially. This in-vitro study was done to compare the flexural strength of six temporary crown and bridge materials available commercially at 24 hours, 8 days and after repair. Three poly methyl methacrylate based materials (DPI, SC10 and Trulon) and three bis-acrylic based composite resins (Protemp, Cooltemp and Luxatemp) were selected. A total of 72 specimens of dimensions 64mm×10mm×2.5mm were prepared from these materials (12 from each material) and divided into two groups (n=36). Specimens were stored in artificial saliva and were fractured after 24 hours and 8 days using Universal Testing Machine. The fractured samples from the 8 days study were then subjected to repair. A uniform space of 2mm and a 450 bevel was maintained for all the repaired samples for better distribution of forces. Flexural strength of these repaired samples was recorded using the same machine. RESULTs were recorded and statistically analysed by one-way Anova and Post hoc tests. RESULTs revealed that there was decrease in flexural strength for all the materials tested from 24 hours to 8 days, though flexural strength between poly methyl methacrylate and bis-acrylic resins was similar at 24 hours and 8 days time interval. A substantial decrease was noticed in the strength of bis-acrylic composite resins after repair. From the current study it can be suggested that though there is decrease in flexural strength for all the materials from 24 hours to 8 days, both can be used to fabricate the provisional restorations. However, in the event of a fracture of a bis-acrylic provisional restoration, it may be more

  5. Progressive outer retinal necrosis presenting as cherry red spot.

    Science.gov (United States)

    Yiu, Glenn; Young, Lucy H

    2012-10-01

    To report a case of progressive outer retinal necrosis (PORN) presenting as a cherry red spot. Case report. A 53-year-old woman with recently diagnosed HIV and varicella-zoster virus (VZV) aseptic meningitis developed rapid sequential vision loss in both eyes over 2 months. Her exam showed a "cherry red spot" in both maculae with peripheral atrophy and pigmentary changes, consistent with PORN. Due to her late presentation and the rapid progression of her condition, she quickly developed end-stage vision loss in both eyes. PORN should be considered within the differential diagnosis of a "cherry red spot." Immune-deficient patients with a history of herpetic infection who present with visual loss warrant prompt ophthalmological evaluation.

  6. Apoptosis and Necrosis in the Liver

    Science.gov (United States)

    Guicciardi, Maria Eugenia; Malhi, Harmeet; Mott, Justin L.; Gores, Gregory J.

    2013-01-01

    Because of its unique function and anatomical location, the liver is exposed to a multitude of toxins and xenobiotics, including medications and alcohol, as well as to infection by hepatotropic viruses, and therefore, is highly susceptible to tissue injury. Cell death in the liver occurs mainly by apoptosis or necrosis, with apoptosis also being the physiologic route to eliminate damaged or infected cells and to maintain tissue homeostasis. Liver cells, especially hepatocytes and cholangiocytes, are particularly susceptible to death receptor-mediated apoptosis, given the ubiquitous expression of the death receptors in the organ. In a quite unique way, death receptor-induced apoptosis in these cells is mediated by both mitochondrial and lysosomal permeabilization. Signaling between the endoplasmic reticulum and the mitochondria promotes hepatocyte apoptosis in response to excessive free fatty acid generation during the metabolic syndrome. These cell death pathways are partially regulated by microRNAs. Necrosis in the liver is generally associated with acute injury (i.e., ischemia/reperfusion injury) and has been long considered an unregulated process. Recently, a new form of “programmed” necrosis (named necroptosis) has been described: the role of necroptosis in the liver has yet to be explored. However, the minimal expression of a key player in this process in the liver suggests this form of cell death may be uncommon in liver diseases. Because apoptosis is a key feature of so many diseases of the liver, therapeutic modulation of liver cell death holds promise. An updated overview of these concepts is given in this article. PMID:23720337

  7. Delayed radiation necrosis in the optochiasmatic region

    International Nuclear Information System (INIS)

    Andoh, Takashi; Yokoyama, Kazutoshi; Kumagai, Morio

    1984-01-01

    Two cases with delayed radiation necrosis of the chiasmatic region following irradiation of the hypophysis for treatment of Cushing's disease were presented. Case 1 was a 36-year-old female who had reduction of visual acuity and bitemporal hemianopsia 2 years after 60 Co-irradiation therapy (total 8000 rads) for Cushing's disease. CT scans showed low density in the pituitary fossa and irregular contrast-enhanced suprasellar mass, and metrizamide CT cisternography revealed the pituitary fossa filled with contrast medium. From those findings, secondary empty sella syndrome was suspicious. Case 2 was a 35-year-old male who had progressive visual disturbance 3 years after 60 Co-irradiation therapy (total 9050 rads) for Cushing's disease. The right visual acuity was 0.05 and the left one was 0.1. Examination of visual field showed left homonymous hemianopsia. CT scans showed the contrast enhanced suprasellar mass extending to the right anterior thalamic region, and metrizamide CT cisternography detected secondary empty sella as same as that of Case 1. Authors reviewed and analyzed literatures of delayed radiation necrosis. The incidence of this condition was 4% to 9% and onset of the symptoms occured approximately 2 years after irradiation to hypophysis. Administration of steroid hormone and surgical treatment for the radiation necrosis involving the chiasmatic region were almost ineffective and also the prognosis of radionecrotic lesions involving the hypothalamus was very poor. Therefore, radiotherapy for hypophyseal region must be carried out by means of a rotation or arching technique in order to avoid this condition and further total dosage and its fractionation in radiation therapy should not exceed 6000 rads and 200 rads a day. (J.P.N.)

  8. Time-variant flexural reliability of RC beams with externally bonded CFRP under combined fatigue-corrosion actions

    International Nuclear Information System (INIS)

    Bigaud, David; Ali, Osama

    2014-01-01

    Time-variant reliability analysis of RC highway bridges strengthened with carbon fibre reinforced polymer CFRP laminates under four possible competing damage modes (concrete crushing, steel rupture after yielding, CFRP rupture and FRP plate debonding) and three degradation factors is analyzed in terms of reliability index β using FORM. The first degradation factor is chloride-attack corrosion which induces reduction in steel area and concrete cover cracking at characteristic key times (corrosion initiation, severe surface cover cracking). The second degradation factor considered is fatigue which leads to damage in concrete and steel rebar. Interaction between corrosion and fatigue crack growth in steel reinforcing bars is implemented. The third degradation phenomenon is the CFRP properties deterioration due to aging. Considering these three degradation factors, the time-dependent flexural reliability profile of a typical simple 15 m-span intermediate girder of a RC highway bridge is constructed under various traffic volumes and under different corrosion environments. The bridge design options follow AASHTO-LRFD specifications. Results of the study have shown that the reliability is very sensitive to factors governing the corrosion. Concrete damage due to fatigue slightly affects reliability profile of non-strengthened section, while service life after strengthening is strongly related to fatigue damage in concrete. - Highlights: • We propose a method to follow the time-variant reliability of strengthened RC beams. • We consider multiple competing failure modes of CFRP strengthened RC beams. • We consider combined degradation mechanisms (corrosion, fatigue, ageing of CFRP)

  9. Reye's syndrome with cortical laminar necrosis: MRI

    International Nuclear Information System (INIS)

    Kinoshita, T.; Takahashi, S.; Ishii, K.; Higano, S.; Matsumoto, K.; Sakamoto, K.; Haginoya, K.; Iinuma, K.

    1996-01-01

    Serial MRI findings are described in two patients with Reye's syndrome, demonstrating diffuse cortical and white matter changes. In the acute stage, T2-weighted images showed subtle but definite laminar high signal and contrast-enhanced T1-weighted images laminar enhancement, along the entire cerebral cortex bilaterally. In the chronic stage, unenhanced T1-weighted images showed diffuse cortical laminar high signal. These characteristic MRI features seemed very similar to those of laminar cortical necrosis in hypoxic brain damage. MRI also displayed delayed white matter changes with cerebral atrophy. (orig.)

  10. A structural model for the flexural mechanics of nonwoven tissue engineering scaffolds.

    Science.gov (United States)

    Engelmayr, George C; Sacks, Michael S

    2006-08-01

    The development of methods to predict the strength and stiffness of biomaterials used in tissue engineering is critical for load-bearing applications in which the essential functional requirements are primarily mechanical. We previously quantified changes in the effective stiffness (E) of needled nonwoven polyglycolic acid (PGA) and poly-L-lactic acid (PLLA) scaffolds due to tissue formation and scaffold degradation under three-point bending. Toward predicting these changes, we present a structural model for E of a needled nonwoven scaffold in flexure. The model accounted for the number and orientation of fibers within a representative volume element of the scaffold demarcated by the needling process. The spring-like effective stiffness of the curved fibers was calculated using the sinusoidal fiber shapes. Structural and mechanical properties of PGA and PLLA fibers and PGA, PLLA, and 50:50 PGA/PLLA scaffolds were measured and compared with model predictions. To verify the general predictive capability, the predicted dependence of E on fiber diameter was compared with experimental measurements. Needled nonwoven scaffolds were found to exhibit distinct preferred (PD) and cross-preferred (XD) fiber directions, with an E ratio (PD/XD) of approximately 3:1. The good agreement between the predicted and experimental dependence of E on fiber diameter (R2 = 0.987) suggests that the structural model can be used to design scaffolds with E values more similar to native soft tissues. A comparison with previous results for cell-seeded scaffolds (Engelmayr, G. C., Jr., et al., 2005, Biomaterials, 26(2), pp. 175-187) suggests, for the first time, that the primary mechanical effect of collagen deposition is an increase in the number of fiber-fiber bond points yielding effectively stiffer scaffold fibers. This finding indicated that the effects of tissue deposition on needled nonwoven scaffold mechanics do not follow a rule-of-mixtures behavior. These important results underscore

  11. FLEXURAL STRESS ANALYSIS OF RIGID PAVEMENTS USING AXI-SYMMETRIC AND PLANE STRAIN FEM

    Directory of Open Access Journals (Sweden)

    V.A. Sawant

    2017-11-01

    Full Text Available The design of pavement involves a study of soils and paving materials, their response under load for different climatic conditions. In the present study, an attempt has been made to compare stresses predicted using two finite element analyses. First analysis is based on the twodimensional plane strain assumption where as in second approach axi-symmetric condition is assumed to consider three-dimensional behavior of rigid pavement. The results are compared with flexural stresses obtained from conventional Portland Cement Association method. The computed flexural stresses obtained from axi-symmetric condition are found to be in close agreement with PCA method. Results of plane strain analysis show a fair agreement after application of an appropriate multiplication factor

  12. The flexural strength and microhardness of YBa2Cu3O6+δ

    International Nuclear Information System (INIS)

    Ihm, M.K.; Powell, B.R.; Bloink, R.L.

    1989-01-01

    The flexural strengths of rectangular YBa 2 Cu 3 O 6+δ bars, prepared from mixed oxides and carbonates, or spray dried precursors have been measured at room temperature and at 77K. Strengths ranged from 17.8 to 57.6 MPa at room temperature, depending on processing history, and were twenty percent greater when measured at 77K. Corrosion of YBa 2 Cu 3 O 6+δ in humid air at 38 0 C created two layers of corrosion products, but did not weaken the uncorroded core when failure loads were corrected for the decreased sample dimensions. The Knoop hardness of polycrystalline YBa 2 Cu 3 O 6+δ ranged from 436 to 447 KHN while the hardness of individual grains of YBa 2 Cu 3 O 6+δ was 498 KHN. Variations in flexural strength with microstructure were observed and are discussed

  13. THE COMPRESSIVE AND FLEXURAL STRENGTHS OF SELF-COMPACTING CONCRETE USING RAW RICE HUSK ASH

    Directory of Open Access Journals (Sweden)

    MD NOR ATAN

    2011-12-01

    Full Text Available This study investigates the compressive and flexural strengths of self-compacting concrete incorporating raw rice husk ash, individually and in combination with other types of mineral additives, as partial cement replacement. The additives paired with raw rice husk ash were fine limestone powder, pulverized fuel ash and silica fumes. The mix design was based on the rational method where solid constituents were fixed while water and superplasticizer contents were adjusted to produce optimum viscosity and flowability. All mixes were designed to achieve SF1 class slump-flow with conformity criteria ≥ 520 mm and ≤ 700 mm. Test results show that 15% replacement of cement using raw rice husk ash produced grade 40 concrete. It was also revealed that 30% and 45% cement replacements using raw rice husk ash combined with limestone powder and raw rice husk ash combined with limestone powder and silica fume respectively, produced comparable compressive strength to normal concrete and improved flexural strengths.

  14. Acoustically Generated Flows in Flexural Plate Wave Sensors: a Multifield Analysis

    Science.gov (United States)

    Sayar, Ersin; Farouk, Bakhtier

    2011-11-01

    Acoustically excited flows in a microchannel flexural plate wave device are explored numerically with a coupled solid-fluid mechanics model. The device can be exploited to integrate micropumps with microfluidic chips. A comprehensive understanding of the device requires the development of coupled two or three-dimensional fluid structure interactive (FSI) models. The channel walls are composed of layers of ZnO, Si3N4 and Al. An isothermal equation of state for the fluid (water) is employed. The flexural motions of the channel walls and the resulting flowfields are solved simultaneously. A parametric analysis is performed by varying the values of the driving frequency, voltage of the electrical signal and the channel height. The time averaged axial velocity is found to be proportional to the square of the wave amplitude. The present approach is superior to the method of successive approximations where the solid-liquid coupling is weak.

  15. Tensile and Flexural Properties of Cement Composites Reinforced with Flax Nonwoven Fabrics

    Directory of Open Access Journals (Sweden)

    Josep Claramunt

    2017-02-01

    Full Text Available The aim of this study is to develop a process to produce high-performance cement-based composites reinforced with flax nonwoven fabrics, analyzing the influence of the fabric structure—thickness and entanglement—on mechanical behavior under flexural and tensile loadings. For this purpose, composite with flax nonwoven fabrics with different thicknesses were first prepared and their cement infiltration was evaluated with backscattered electron (BSE images. The nonwoven fabrics with the optimized thickness were then subjected to a water treatment to improve their stability to humid environments and the fiber-matrix adhesion. For a fixed thickness, the effect of the nonwoven entanglement on the mechanical behavior was evaluated under flexural and direct tension tests. The obtained results indicate that the flax nonwoven fabric reinforcement leads to cement composites with substantial enhancement of ductility.

  16. Plate-shaped non-contact ultrasonic transporter using flexural vibration.

    Science.gov (United States)

    Ishii, Takahiko; Mizuno, Yosuke; Koyama, Daisuke; Nakamura, Kentaro; Harada, Kana; Uchida, Yukiyoshi

    2014-02-01

    We developed a plate-shaped non-contact transporter based on ultrasonic vibration, exploiting a phenomenon that a plate can be statically levitated at the place where its gravity and the acoustic radiation force are balanced. In the experiment, four piezoelectric zirconate titanate elements were attached to aluminum plates, on which lattice flexural vibration was excited at 22.3 kHz. The vibrating plates were connected to a loading plate via flexible posts that can minimize the influence of the flexure induced by heavy loads. The distribution of the vibration displacement on the plate was predicted through finite-element analysis to find the appropriate positions of the posts. The maximum levitation height of this transporter was 256 μm with no load. When two vibrating plates were connected to a loading plate, the maximum transportable load was 4.0 kgf. Copyright © 2013. Published by Elsevier B.V.

  17. Ice-Shelf Flexure and Tidal Forcing of Bindschadler Ice Stream, West Antarctica

    Science.gov (United States)

    Walker, Ryan T.; Parizek, Bryron R.; Alley, Richard B.; Brunt, Kelly M.; Anandakrishnan, Sridhar

    2014-01-01

    Viscoelastic models of ice-shelf flexure and ice-stream velocity perturbations are combined into a single efficient flowline model to study tidal forcing of grounded ice. The magnitude and timing of icestream response to tidally driven changes in hydrostatic pressure and/or basal drag are found to depend significantly on bed rheology, with only a perfectly plastic bed allowing instantaneous velocity response at the grounding line. The model can reasonably reproduce GPS observations near the grounding zone of Bindschadler Ice Stream (formerly Ice Stream D) on semidiurnal time scales; however, other forcings such as tidally driven ice-shelf slope transverse to the flowline and flexurally driven till deformation must also be considered if diurnal motion is to be matched

  18. TWO-DIMENSIONAL APPROXIMATION OF EIGENVALUE PROBLEMS IN SHELL THEORY: FLEXURAL SHELLS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The eigenvalue problem for a thin linearly elastic shell, of thickness 2e, clamped along its lateral surface is considered. Under the geometric assumption on the middle surface of the shell that the space of inextensional displacements is non-trivial, the authors obtain, as ε→0,the eigenvalue problem for the two-dimensional"flexural shell"model if the dimension of the space is infinite. If the space is finite dimensional, the limits of the eigenvalues could belong to the spectra of both flexural and membrane shells. The method consists of rescaling the variables and studying the problem over a fixed domain. The principal difficulty lies in obtaining suitable a priori estimates for the scaled eigenvalues.

  19. Flexural Behaviour of Precast Aerated Concrete Panel (PACP with Added Fibrous Material: An Overview

    Directory of Open Access Journals (Sweden)

    Abdul Rahim Noor Hazlin

    2017-01-01

    Full Text Available The usage of precast aerated concrete panel as an IBS system has become the main alternative to conventional construction system. The usage of this panel system contributes to a sustainable and environmental friendly construction. This paper presents an overview of the precast aerated concrete panel with added fibrous material (PACP. PACP is fabricated from aerated foamed concrete with added Polypropylene fibers (PP. The influence of PP on the mechanical properties of PACP are studied and reviewed from previous research. The structural behaviour of precast concrete panel subjected to flexure load is also reviewed. It is found that PP has significant affects on the concrete mixture’s compressive stregth, tensile strength and flexural strength. It is also found that PP manage to control the crack propagation in the concrete panel.

  20. Flexural behaviour of post-cured composites at oral-simulating temperatures.

    Science.gov (United States)

    Ho, C T; Vijayaraghavan, T V; Lee, S Y; Tsai, A; Huang, H M; Pan, L C

    2001-07-01

    Post-curing treatments have been known to improve the mechanical stability of visible light-cured composites. After individual post-curing treatment, the flexural strength (FS) of four commercial direct/indirect placement composite materials which differ greatly in composition [oligocarbonate dimethacrylate (OCDMA)-based Conquest C & B (CQT), Bisphenol-A glycidyl dimethacrylate (BisGMA)-based Charisma, urethane dimethacrylate (UDMA)-based Concept (CCT), and BisGMA/UDMA-based Dentacolor] was evaluated under water in the temperature range of 12-50 degrees C. A control series was tested in air at room temperature (25 +/- 1 degrees C). Data were analysed using ANOVA and Duncan's test. Flexural strengths overall decreased (20-40%, P OCDMA-based materials. Post-cured composites can be significantly affected by exposure to oral environments. Different composition determines the degree of influence.

  1. Flexural strengthening of Reinforced Concrete (RC) Beams Retrofitted with Corrugated Glass Fiber Reinforced Polymer (GFRP) Laminates

    Science.gov (United States)

    Aravind, N.; Samanta, Amiya K.; Roy, Dilip Kr. Singha; Thanikal, Joseph V.

    2015-01-01

    Strengthening the structural members of old buildings using advanced materials is a contemporary research in the field of repairs and rehabilitation. Many researchers used plain Glass Fiber Reinforced Polymer (GFRP) sheets for strengthening Reinforced Concrete (RC) beams. In this research work, rectangular corrugated GFRP laminates were used for strengthening RC beams to achieve higher flexural strength and load carrying capacity. Type and dimensions of corrugated profile were selected based on preliminary study using ANSYS software. A total of twenty one beams were tested to study the load carrying capacity of control specimens and beams strengthened with plain sheets and corrugated laminates using epoxy resin. This paper presents the experimental and theoretical study on flexural strengthening of Reinforced Concrete (RC) beams using corrugated GFRP laminates and the results are compared. Mathematical models were developed based on the experimental data and then the models were validated.

  2. Mechanical properties and flexure behaviour of lightweight foamed concrete incorporating coir fibre

    Science.gov (United States)

    Mohamad, Noridah; Afif Iman, Muhamad; Othuman Mydin, M. A.; Samad, A. A. A.; Rosli, J. A.; Noorwirdawati, A.

    2018-04-01

    This paper presents an experimental investigation on the mechanical properties and flexural behaviour of lightweight foamed concrete (LFC) with added coir fibre as filler. The compressive strength (Pt), tensile strength (Ft), modulus of elasticity (E), ultimate load and crack pattern of the foamed concrete were determined. The coir fibre was added to the foamed concrete mixture at 0.1%, 0.2% and 0.3% of the total weight of cement. Effects of various percentage of coir fibre used on foam concrete’s mechanical and properties and flexural behaviour were studied and analysed. It was found that the increase percentage of fibre resulted in increase in compressive strength, tensile strength and modulus of elasticity of LFC mixture. LFC with added coir of 0.3% experienced the smallest crack propagation.

  3. Modeling and design of a two-axis elliptical notch flexure hinge

    Science.gov (United States)

    Wu, Jianwei; Zhang, Yin; Lu, Yunfeng; Wen, Zhongpu; Bin, Deer; Tan, Jiubin

    2018-04-01

    As an important part of the joule balance system, the two-axis elliptical notch flexure hinge (TENFH) which typically consists of two single-axis elliptical notch flexure hinges was studied. First, a 6 degrees of freedom (6-DOF) compliance model was established based on the coordinate transformation method. In addition, the maximum stress of the TENFH was derived. The compliance and maximum stress model was verified using finite element analysis simulation. To decouple the attitude of the suspended coil system and reduce the offset between the centroid of the suspended coil mechanism and the mass comparator in the joule balance system, a new mechanical structure of TENFH was designed based on the compliance model and stress model proposed in this paper. The maximum rotation range is up to 10°, and the axial load is more than 5 kg, which meets the requirements of the system. The compliance model was also verified by deformation experimentation with the designed TENFH.

  4. Determining the optimum topology of composites by the flexural stiffness criterion

    Directory of Open Access Journals (Sweden)

    Vasile MOGA

    2012-06-01

    Full Text Available An important stage in designing of pieces made of composite materials consists of establishing the composite topology in such a way that it has certain properties needed in exploitation. The paper presents the mathematical apparatus and the calculation programme for establishing the optimum thickness of the composite groups so that it should have certain imposed (given flexural stiffness. The method is applicable to all types of laminate composites, no matter of the cladding or matrix nature. The direct problem consists in determining the thickness of the groups and composite, minimising the bar mass, for an imposed (given flexural stiffness, knowing the densities and elasticity modules of the groups. The indirect problem consists in determining the maximum stiffness, the thickness of the groups and composite for a given (imposed mass, knowing the densities and elasticity modules of the groups. The presented programmes offer to the producer of this kind of materials the possibility to quickly establish the optimum topology.

  5. Analysis on Flexural Strength of A36 Mild Steel by Design of Experiment (DOE)

    Science.gov (United States)

    Nurulhuda, A.; Hafizzal, Y.; Izzuddin, MZM; Sulawati, MRN; Rafidah, A.; Suhaila, Y.; Fauziah, AR

    2017-08-01

    Nowadays demand for high quality and reliable components and materials are increasing so flexural tests have become vital test method in both the research and manufacturing process and development to explain in details about the material’s ability to withstand deformation under load. Recently, there are lack research studies on the effect of thickness, welding type and joint design on the flexural condition by DOE approach method. Therefore, this research will come out with the flexural strength of mild steel since it is not well documented. By using Design of Experiment (DOE), a full factorial design with two replications has been used to study the effects of important parameters which are welding type, thickness and joint design. The measurement of output response is identified as flexural strength value. Randomize experiments was conducted based on table generated via Minitab software. A normal probability test was carried out using Anderson Darling Test and show that the P-value is <0.005. Thus, the data is not normal since there is significance different between the actual data with the ideal data. Referring to the ANOVA, only factor joint design is significant since the P-value is less than 0.05. From the main plot and interaction plot, the recommended setting for each of parameters were suggested as high level for welding type, high level for thickness and low level for joint design. The prediction model was developed thru regression in order to measure effect of output response for any changes on parameters setting. In the future, the experiments can be enhanced using Taguchi methods in order to do verification of result.

  6. Acousto-optic interaction in polyimide coated optical fibers with flexural waves

    OpenAIRE

    ALCUSA-SÁEZ, E. P.; Díez, A.; Rivera-Pérez, E.; Margulis, W.; Norin, L.; Andrés, M. V.

    2017-01-01

    Acousto-optic coupling in polyimide-coated single-mode optical fibers using flexural elastic waves is demonstrated. The effect of the polyimide coating on the acousto-optic interaction process is analyzed in detailed. Theoretical and experimental results are in good agreement. Although the elastic attenuation is significant, we show that acousto-optic coupling can be produced with a reasonably good efficiency. To our knowledge, it is the first experimental demonstration of acousto-optic coupl...

  7. Determining the Compressive, Flexural and Splitting Tensile Strength of Silica Fume Reinforced Lightweight Foamed Concrete

    OpenAIRE

    Mydin M.A.O.; Sani N. Md.; Mohd Yusoff M.A.; Ganesan S.

    2014-01-01

    This study investigated the performance of the properties of foamed concrete in replacing volumes of cement of 10%, 15% and 20% by weight. A control unit of foamed concrete mixture made with ordinary Portland cement (OPC) and 10%, 15% and 20% silica fume was prepared. Three mechanical property parameters were studied such as compressive strength, flexural strength and splitting tensile of foamed concrete with different percentages of silica fume. Silica fume is commonly used to increase the m...

  8. Study on reinforced lightweight coconut shell concrete beam behavior under flexure

    International Nuclear Information System (INIS)

    Gunasekaran, K.; Annadurai, R.; Kumar, P.S.

    2013-01-01

    Highlights: ► Use of coconut shell as aggregate in concrete. ► Behavior of coconut shell concrete under flexure. ► SEM images of cement, sand, coconut shell and coconut shell aggregate concrete. ► Coconut shell hollow blocks and precast slabs are used in practice. - Abstract: Coconut shell has been used as coarse aggregate in the production of concrete. The flexural behavior of reinforced concrete beam made with coconut shell is analyzed and compared with the normal control concrete. Twelve beams, six with coconut shell concrete and six with normal control concrete, were fabricated and tested. This study includes the moment capacity, deflection, cracking, ductility, corresponding strains in both compression and tension, and end rotation. It was found that the flexural behavior of coconut shell concrete is comparable to that of other lightweight concretes. The results of concrete compression strain and steel tension strain showed that coconut shell concrete is able to achieve its full strain capacity under flexural loadings. Under serviceability condition, deflection and cracking characteristics of coconut shell concrete are comparable with control concrete. However, the failure zones of coconut shell concrete were larger than for control concrete beams. The end rotations of the coconut shell concrete beams just prior to failure values are comparable to other lightweight concretes. Coconut shell concrete was used to produce hollow blocks and precast slab in 2007 and they are being subjected to some practical loading till today without any problems such as deflection, bending, cracks, and damages for the past five years

  9. Minimum bar size for flexure testing of irradiated SiC/SiC composite

    International Nuclear Information System (INIS)

    Youngblood, G.E.; Jones, R.H.

    1998-01-01

    This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23-24, 1997. The minimum bar size for 4-point flexure testing of SiC/SiC composite recommended by PNNL for irradiation effects studies is 30 x 6 x 2 mm 3 with a span-to-depth ratio of 10/1

  10. Deflection and Flexural Strength Effects on the Roughness of Aesthetic-Coated Orthodontic Wires

    OpenAIRE

    Albuquerque, Cibele Gonçalves de; Correr, Américo Bortolazzo; Venezian, Giovana Cherubini; Santamaria Jr, Milton; Tubel, Carlos Alberto; Vedovello, Silvia Amélia Scudeler

    2017-01-01

    Abstract The aim was to evaluate the flexural strength and the effects of deflection on the surface roughness of esthetic orthodontic wires. The sample consisted of 70 archwire 0.014-inch: polytetrafluorethylene (PTFE)-coated Nickel-Titanium (Niti) archwires (Titanol Cosmetic-TC, Flexy Super Elastic Esthetic-FSE, esthetic Nickel Titanium Wire-ANT); epoxy resin-coated Niti archwires (Spectra-S, Niticosmetic-TEC); gold and rhodium coated Niti (Sentalloy-STC) and a control group (superelastic Ni...

  11. Flexural Strength Of Prestressed Concrete Beams With Openings And Strengthened With CFRP Sheets

    Directory of Open Access Journals (Sweden)

    Dr. Mustafa B. Dawood

    2015-06-01

    Full Text Available Abstract This paper presents an experimental investigation of flexural strength of pretensioned prestressed concrete beams with openings and strengthened with CFRP sheets tested as simply supported span subjected under two-point loading. The experimental work includes testing of nine prestressed concrete beams specimens with dimensions effective length 1800mm depth 300mm width 130mm two of which were without openings as a control beams one without and the other with strengthening by CFRP three were with openings and the remaining four with openings and strengthened with CFRP sheets. The opening was made at square shape 100100 mm in flexure zone at mid span of beam. Several design parameters were varied such as opening width opening depth and strengthening of openings of beams by CFRP sheets at compression and tension zone. Experimental results showed that the presence of square opening with ratio hH 0.333 and rectangular opening with ratio hH from 0.333-0.5 at mid span of beams decreased the ultimate load about 5.5 and 5.5-33.1 respectively when compared with beam without openings control beam. The externally strengthened prestressed concrete beams with bonded CFRP sheets showed a significant increase at the ultimate load this increase was about 10.9-28.8 for flexure beams when compared with the unstrengthened beams. Moreover the load-deflection curves for flexure beams strengthened with CFRP sheets were stiffer than the unstrengthened beams. Therefore this results gave a good indication about using CFRP sheets in improvement of deflection.

  12. Signatures of Lithospheric Flexure and Elevated Heat Flow in Stereo Topography at Coronae on Venus

    Science.gov (United States)

    O'Rourke, Joseph G.; Smrekar, Suzanne E.

    2018-02-01

    Signatures of lithospheric flexure were previously identified at a dozen or more large coronae on Venus. Thin plate models fit to topographic profiles return elastic parameters, allowing derivation of mechanical thickness and surface heat flows given an assumed yield strength envelope. However, the low resolution of altimetry data from the NASA Magellan mission has hindered studying the vast majority of coronae, particularly those less than a few hundred kilometers in diameter. Here we search for flexural signatures around 99 coronae over ˜20% of the surface in Magellan altimetry data and stereo-derived topography that was recently assembled from synthetic aperture radar images. We derive elastic thicknesses of ˜2 to 30 km (mostly ˜5 to 15 km) with Cartesian and axisymmetric models at 19 coronae. We discuss the implications of low values that were also noted in earlier gravity studies. Most mechanical thicknesses are estimated as 24 K km-1. Implied surface heat flows >95 mW m-2—twice the global average in many thermal evolution models—imply that coronae are major contributors to the total heat budget or Venus is cooling faster than expected. Binomial statistics show that "Type 2" coronae with incomplete fracture annuli are significantly less likely to host flexural signatures than "Type 1" coronae with largely complete annuli. Stress calculations predict extensional faulting where nearly all profiles intersect concentric fractures. We failed to identify systematic variations in flexural parameters based on type, geologic setting, or morphologic class. Obtaining quality, high-resolution topography from a planetwide survey is vital to verifying our conclusions.

  13. Heat treatment of a direct composite resin: influence on flexural strength

    Directory of Open Access Journals (Sweden)

    Caroline Lumi Miyazaki

    2009-09-01

    Full Text Available The purpose of this study was to evaluate the flexural strength of a direct composite, for indirect application, that received heat treatment, with or without investment. One indirect composite was used for comparison. For determination of the heat treatment temperature, thermogravimetric analysis (TGA and differential scanning calorimetry (DSC were performed, considering the initial weight loss temperature and glass transition temperature (Tg. Then, after photoactivation (600 mW/cm² - 40 s, the specimens (10 x 2 x 2 mm were heat-treated following these conditions: 170ºC for 5, 10 or 15 min, embedded or not embedded in investment. Flexural strength was assessed as a means to evaluate the influence of different heat treatment periods and investment embedding on mechanical properties. The data were analyzed by ANOVA and Tukey's test (α = 0.05. TGA showed an initial weight loss temperature of 180ºC and DSC showed a Tg value of 157°C. Heat treatment was conducted in an oven (Flli Manfredi, Italy, after 37°C storage for 48 h. Flexural strength was evaluated after 120 h at 37°C storage. The results showed that different periods and investment embedding presented similar statistical values. Nevertheless, the direct composite resin with treatments presented higher values (178.7 MPa compared to the indirect composite resin (146.0 MPa and the same direct composite submitted to photoactivation only (151.7 MPa. Within the limitations of this study, it could be concluded that the heat treatment increased the flexural strength of the direct composite studied, leading to higher mechanical strength compared to the indirect composite.

  14. FLEXURAL CAPACITY OF THE PRECAST RC BEAM-COLUMN CONNECTION USING CFRP SHEET

    OpenAIRE

    Djamaluddin, Rudy; Rante, Harmonis; Irmawaty, Rita

    2016-01-01

    Precast concrete have advantages in quality and shorter construction time. The connection of a precast concrete structures is important for the successful construction. This paper presents an experimental investigation of the flexural capacity of the portal system beam-column connection of precast concrete using CFRP sheet. The study was conducted to develop a connection system using CFRP sheet on a precast concrete frame of a highway bridges. A series of specimens with parameter of CFRP shee...

  15. Feasibility of Reducing the Fiber Content in Ultra-High-Performance Fiber-Reinforced Concrete under Flexure.

    Science.gov (United States)

    Park, Jung-Jun; Yoo, Doo-Yeol; Park, Gi-Joon; Kim, Sung-Wook

    2017-01-28

    In this study, the flexural behavior of ultra-high-performance fiber-reinforced concrete (UHPFRC) is examined as a function of fiber length and volume fraction. Straight steel fiber with three different lengths ( l f ) of 13, 19.5, and 30 mm and four different volume fractions ( v f ) of 0.5%, 1.0%, 1.5%, and 2.0% are considered. Test results show that post-cracking flexural properties of UHPFRC, such as flexural strength, deflection capacity, toughness, and cracking behavior, improve with increasing fiber length and volume fraction, while first-cracking properties are not significantly influenced by fiber length and volume fraction. A 0.5 vol % reduction of steel fiber content relative to commercial UHPFRC can be achieved without deterioration of flexural performance by replacing short fibers ( l f of 13 mm) with longer fibers ( l f of 19.5 mm and 30 mm).

  16. An avascular necrosis in Gaucher's disease

    International Nuclear Information System (INIS)

    Mansberg, R.; Uren, R.; Howman-Giles, R.

    1999-01-01

    Full text: Avascular necrosis is frequently associated with sickle cell disease and other haemoglobinopathies. It is less commonly associated with Gaucher's disease. A case with multi-modality imaging is presented. A 33-year-old male patient presented with a 4-day history of severe right knee pain. He was a febrile with mild swelling of the right knee. A diagnosis of Gaucher's disease had been made by bone marrow biopsy on a clinical picture of hepatosplenomegaly and thrombocytopenia some years earlier. A radiograph of the knee demonstrated an Erlenmeyer flask deformity of the distal femur. A bone scan demonstrated reduced perfusion to the distal right femoral shaft and femoral condyles. Delayed images demonstrated decreased tracer uptake in the distal right femur extending to the right medial femoral condyle consistent with a vascular necrosis. An MRI of the thighs demonstrated lipid accumulation in the marrow space of both femora consistent with Gaucher's disease associated with changes of bone oedema in the metadiaphysis and epiphysis of the right femur. The patient was treated with supportive measures and made an uneventful recovery and is being commenced on enzyme replacement therapy (Algucerase)

  17. Avascular necrosis of the femoral head

    International Nuclear Information System (INIS)

    Kokubo, Takeshi; Takatori, Yoshio; Kamogawa, Morihide; Nakamura, Toshitaka; Ninomiya, Setsuo; Yoshikawa, Kohki; Itai, Yuji; Iio, Masahiro; Mitamura, Tadayuki

    1990-01-01

    T1-weighted MR images of thirty-six hips in 25 patients with avascular necrosis of the femoral head were obtained two to five times during the course of 2 to 26 months. We investigated these MR images in the light of the chronological change and compared them with plain radiographs. MR images changes in 16 femoral head; in general, the abnormal low intensity area in the femoral head reduced in extent and the internal high intensity area became smaller of disappeared. Thirteen femoral heads among them became more flattened on plain radiographs in the same period. It is noted that four different zones are defined in the femoral head after bone necrosis takes place: the dead bone marrow, the dead marrow which still contains fat, the reactive interface and the hyperemic bone marrow. In T1-weighted MR images, the dead bone marrow, the reactive interface and the hyperemic bone marrow are demonstrated as low intensity area, while the dead marrow containing fat may remain high in intensity. On the basis of this knowledge of histopathology and MR images of this disease, we suggest that reduction of the abnormal low intensity area and disappearance of the internal high intensity area on MR images can be regarded as diminution of hyperemia in the living bone marrow and loss of fat in the dead bone marrow, respectively. (author)

  18. Myoglobinaemia in relation to cardiac necrosis

    Energy Technology Data Exchange (ETDEWEB)

    McComb, J M

    1981-01-01

    An evaluation of the usefulness of estimation of the serum myoglobin in the detection of myocardial necrosis was made in patients with suspected acute ischemic heart disease and in patients in whom elective cardiac catheterization was performed. Measurement of serum myoglobin, by radioimmunoassay, in patients admitted with suspected acute myocardial infarction, suggested that a raised serum myoglobin level was a sensitive indicator of myocardial necrosis. It also showed that the serum myoglobin rose to abnormal levels before the serum creatine kinase. A study of 70 consecutive patients confirmed that the serum myoglobin level is a sensitive indicator of acute myocardial infarction and showed that its sensitivity was greater, and its specificity similar to that of serum creatine kinase. This study allowed calculation of a predictive index for the diagnosis of acute myocardial infarction from the serum myoglobin and serum creatine kinase six hours after the onset of symptoms. The use of a single myoglobin measurement in 114 patients admitted to a coronary care unit was then studied. The proposition that myocardial damage might results from cardiac catheterization was investigated in 115 patients.

  19. Effect of metal chloride solutions on coloration and biaxial flexural strength of yttria-stabilized zirconia

    Science.gov (United States)

    Oh, Gye-Jeong; Lee, Kwangmin; Lee, Doh-Jae; Lim, Hyun-Pil; Yun, Kwi-Dug; Ban, Jae-Sam; Lee, Kyung-Ku; Fisher, John G.; Park, Sang-Won

    2012-10-01

    The effect of three kinds of transition metal dopants on the color and biaxial flexural strength of zirconia ceramics for dental applications was evaluated. Presintered zirconia discs were colored through immersion in aqueous chromium, molybdenum and vanadium chloride solutions and then sintered at 1450 °C. The color of the doped specimens was measured using a digital spectrophotometer. For biaxial flexural strength measurements, specimens infiltrated with 0.3 wt% of each aqueous chloride solution were used. Uncolored discs were used as a control. Zirconia specimens infiltrated with chromium, molybdenum and vanadium chloride solutions were dark brown, light yellow and dark yellow, respectively. CIE L*, a*, and b* values of all the chromium-doped specimens and the specimens infiltrated with 0.1 wt% molybdenum chloride solution were in the range of values for natural teeth. The biaxial flexural strengths of the three kinds of metal chloride groups were similar to the uncolored group. These results suggest that chromium and molybdenum dopants can be used as colorants to fabricate tooth colored zirconia ceramic restorations.

  20. Fresh Properties and Flexural Strength of Self-Compacting Concrete Integrating Coal Bottom Ash

    Directory of Open Access Journals (Sweden)

    Jamaluddin Norwati

    2016-01-01

    Full Text Available This paper presents the effect of using coal bottom ash as a partial replacement of fine aggregates in self-compacting concrete (SCC on its fresh properties and flexural strength. A comparison between SCC with various replacements of fine aggregates with coal bottom ash showed that SCC obtained flexural strength decrease on increase of water cement ratio from 0.35 to 0.45. The natural sand was replaced with coal bottom ash up to 30% volumetrically. The fresh properties were investigated by slump flow, T500 spread time, L-box test and sieve segregation resistance in order to evaluate its self-compatibility by compared to control samples embed with natural sand. The results revealed that the flowability and passing ability of SCC mixtures are decreased with higher content of coal bottom ash replacement. The results also showed that the flexural strength is affected by the presence of coal bottom ash in the concrete. In addition, the water cement ratios are influence significantly with higher binder content in concrete.

  1. Flexural and Thermal Properties of Novel Energy Conservation Slotted Reinforced Concrete Beams

    Directory of Open Access Journals (Sweden)

    Gao Ma

    2016-01-01

    Full Text Available Conventional solid reinforced concrete (RC beams were modified to slotted beams for consideration as thermal insulation structural components. The slotted beam consisted of an outer and an inner beam, respectively, with a slot located near the middle of the beam along its width direction for filling thermal insulation material. Flexural and thermal behavior of the slotted beams were investigated. Three RC reference solid beams and six slotted beams were fabricated and tested under four-point bending tests. The test results indicated that the failure mode of both slotted beams and the solid beams was flexural failure. However, the damage process of the slotted beams was different from that of the solid beams at the final loading stage. The moment curvature analysis indicated that the tensile reinforcement ratio of the outer and inner beams had an important effect on the flexural behavior, especially the ductility of the slotted beams. Thermal study indicated that the heat transfer coefficient of the slotted beam was greatly reduced and the thermal inertia factor increased a lot, compared with the solid beam. In addition, FE simulation results showed that a new frame structure using slotted beams exhibited obvious and attractive thermal insulation property.

  2. A novel constrained H2 optimization algorithm for mechatronics design in flexure-linked biaxial gantry.

    Science.gov (United States)

    Ma, Jun; Chen, Si-Lu; Kamaldin, Nazir; Teo, Chek Sing; Tay, Arthur; Mamun, Abdullah Al; Tan, Kok Kiong

    2017-11-01

    The biaxial gantry is widely used in many industrial processes that require high precision Cartesian motion. The conventional rigid-link version suffers from breaking down of joints if any de-synchronization between the two carriages occurs. To prevent above potential risk, a flexure-linked biaxial gantry is designed to allow a small rotation angle of the cross-arm. Nevertheless, the chattering of control signals and inappropriate design of the flexure joint will possibly induce resonant modes of the end-effector. Thus, in this work, the design requirements in terms of tracking accuracy, biaxial synchronization, and resonant mode suppression are achieved by integrated optimization of the stiffness of flexures and PID controller parameters for a class of point-to-point reference trajectories with same dynamics but different steps. From here, an H 2 optimization problem with defined constraints is formulated, and an efficient iterative solver is proposed by hybridizing direct computation of constrained projection gradient and line search of optimal step. Comparative experimental results obtained on the testbed are presented to verify the effectiveness of the proposed method. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  3. Flexural behaviour of reinforced concrete beams with discrete steel – polypropylene fibres

    Directory of Open Access Journals (Sweden)

    Amizah Wan Jusoh Wan

    2017-01-01

    Full Text Available This paper discusses the experimental results on the flexural test of concrete containing different proportions of steel fibre (SF and polypropylene fibre (PPF. The flexural test was carried out under 4-point bending load and followed the relevant standards to FRC. Hooked-end deformed SF fibre with 60 mm length and fibrillated virgin PPF fibre with 19 mm length were used in this study. Meanwhile, the concrete was designed for high strength concrete of C60. The mixture included both single SF and PPF, and also the combination of both fibres; Control beam (PC, beam with 75%SF, beam with 75%SF + 25%PPF and beam with 25%PPF. The total fibre volume fraction (Vf was fixed at 1.5%. The experimental results show that the percentage proportion of combined SF-PPF at 75-25% had the best performance for its flexural capacity. Mixture with single PPF was also found not effective in delaying the onset of tension cracks and to increase the tensile strength of the concrete. Experimental result also shows beam with 75%SF +25%PPF had their structural stiffness improved the most as compared with the others. For the compressive strength, beam with 75%SF + 25%PPF also revealed comparable performance with the control for high strength composite concrete.

  4. Flexural and Shear Behavior of RC Concrete Beams Reinforced with Fiber Wire Mesh

    Directory of Open Access Journals (Sweden)

    Rafea Flaih Hassan

    2018-02-01

    Full Text Available This work aims to study  the effect of using fiber wire mesh on the flexural and shear properties of RC concrete beams. Six reinforced concrete beams (120*180*1220mm were tested under two load points. Fiber wire mesh was applied with two manners, first one is three layers as U shape around the section of the beam, the second one is four layers around overall section of beam. The test results indicated that using of fiber wire mesh as additional reinforcement can increase the ultimate load of about (1.85-3.58% in the case of flexural and (17.7-23.7% in case of shear. Also,  results showed that an increasing in  first cracking  load is obtained from  (42.8-85.7% in case of flexural and from (41.2-76.5% in case of shear. Also the shear behavior of beams becomes more ductile when the fiber wire mesh was used in beams. The cracks of shrinkage was disappeared when the fiber wire mesh surround the section of the beam. 

  5. Flexural and Shear Behavior of FRP Strengthened AASHTO Type Concrete Bridge Girders

    Directory of Open Access Journals (Sweden)

    Nur Yazdani

    2016-01-01

    Full Text Available Fiber-reinforced polymers (FRP are being increasingly used for the repair and strengthening of deteriorated or unsafe concrete structures, including structurally deficient concrete highway bridges. The behavior of FRP strengthened concrete bridge girders, including failure modes, failure loads, and deflections, can be determined using an analytical finite element modeling approach, as outlined in this paper. The differences in flexural versus shear FRP strengthening and comparison with available design guidelines are also beneficial to design professionals. In this paper, a common AASHTO type prestressed concrete bridge girder with FRP wrapping was analyzed using the ANSYS FEM software and the ACI analytical approach. Both flexural and shear FRP applications, including vertical and inclined shear strengthening, were examined. Results showed that FRP wrapping can significantly benefit concrete bridge girders in terms of flexure/shear capacity increase, deflection reduction, and crack control. The FRP strength was underutilized in the section selected herein, which could be addressed through decrease of the amount of FRP and prestressing steel used, thereby increasing the section ductility. The ACI approach produced comparable results to the FEM and can be effectively and conveniently used in design.

  6. An Experimental Study on Strengthening of Reinforced Concrete Flexural Members using Steel Wire Mesh

    Directory of Open Access Journals (Sweden)

    Al Saadi Hamza Salim Mohammed

    2017-01-01

    Full Text Available One of the major challenges and contemporary research in the field of structural engineering is strengthening of existing structural elements using readily available materials in the market. Several investigations were conducted on strengthening of various structural components using traditional and advanced materials. Many researchers tried to enhance the reinforced concrete (RC beams strength using steel plate, Glass and Carbon Fibre Reinforced Polymers (GFRP & CFRP. For the reason that high weight to the strength ratio and compatibility in strength between FRP composites and steel bars, steel plates and GFRP and CFRP composites are not used for strengthening works practically. Hence, in this present work the suitability of using wire mesh for the purpose of strengthening the RC flexural members is studied by conducting experimental works. New technique of strengthening system using wire mesh with a view to improve sectional properties and subsequently flexural strength of RC beams is adopted in this work. The results for experimental and theoretical analysis were compared and found that good correlation exists between them. The experimental results indicate that RC beams strengthened with steel wire mesh are easy technique for strengthening of existing flexural members.

  7. Development of partial safety factors for the design of partially prestressed rectangular sections in biaxial flexure

    International Nuclear Information System (INIS)

    Chatterjee, Aritra; Bhattacharya, Baidurya; Agrawal, Gunjan; Mondal, Apurba

    2011-01-01

    Partial safety factors (PSFs) used in reliability-based design are intended to account for uncertainties in load, material and mathematical modeling while ensuring that the target reliability is satisfied for the relevant class of structural components in the given load combination and limit state. This paper describes the methodology in detail for developing a set of optimal reliability-based PSFs for the design of rectangular partially prestressed concrete sections subjected to biaxial flexure. The mechanical formulation of the flexural limit state is based on the principle behind prestressed concrete design recommended by IS 1343 and SP16 and failure is defined as tensile cracking of concrete extending beyond the depth of cover. The applied moments are combined according to Wood's criteria. The optimization of the PSFs is based on reliability indices obtained from first order reliability analysis of the structural components; Monte Carlo simulations are performed in each run to determine the capacity statistics and dependence between capacity and applied loads (effected through the axial loads influencing moment capacity corresponding to cracking). Numerical examples involving flexural design of partially prestressed concrete shell elements in nuclear power plant containments under accidental pressure load combination are provided. (author)

  8. Static flexural properties of hedgehog spines conditioned in coupled temperature and relative humidity environments.

    Science.gov (United States)

    Kennedy, Emily B; Hsiung, Bor-Kai; Swift, Nathan B; Tan, Kwek-Tze

    2017-11-01

    Hedgehogs are agile climbers, scaling trees and plants to heights exceeding 10m while foraging insects. Hedgehog spines (a.k.a. quills) provide fall protection by absorbing shock and could offer insights for the design of lightweight, material-efficient, impact-resistant structures. There has been some study of flexural properties of hedgehog spines, but an understanding of how this keratinous biological material is affected by various temperature and relative humidity treatments, or how spine color (multicolored vs. white) affects mechanics, is lacking. To bridge this gap in the literature, we use three-point bending to analyze the effect of temperature, humidity, spine color, and their interactions on flexural strength and modulus of hedgehog spines. We also compare specific strength and stiffness of hedgehog spines to conventional engineered materials. We find hedgehog spine flexural properties can be finely tuned by modifying environmental conditioning parameters. White spines tend to be stronger and stiffer than multicolored spines. Finally, for most temperature and humidity conditioning parameters, hedgehog spines are ounce for ounce stronger than 201 stainless steel rods of the same diameter but as pliable as styrene rods with a slightly larger diameter. This unique combination of strength and elasticity makes hedgehog spines exemplary shock absorbers, and a suitable reference model for biomimicry. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Flexural strength and modulus of elasticity of different types of resin-based composites.

    Science.gov (United States)

    Rodrigues Junior, Sinval Adalberto; Zanchi, Cesar Henrique; Carvalho, Rodrigo Varella de; Demarco, Flávio Fernando

    2007-01-01

    The aim of the study was to test whether the filler composition of resin composites influences their flexural strength and modulus of elasticity. Flexural strength and modulus of elasticity were obtained through a three-point bending test. Twelve bar shaped specimens of 5 commercially available composites--Supreme (3M/ESPE), a universal nanofilled composite; Esthet-X (Dentsply), Z-250 (3M/ESPE), Charisma (Heraeus Kulzer), universal hybrid composites; and Helio Fill (Vigodent), a microfine composite--were confectioned according to the ISO 4049/2000 specifications. The test was performed after a 7-days storage time using a universal test machine with a crosshead speed of 1 mm/min. The filler weight content was determined by the ashing technique. The data obtained on the mechanical properties were submitted to ANOVA and Tukey test (p elasticity results were observed among the universal hybrid composites. The nanofilled composite presented intermediary results. Within the limitations of this in vitro study, it could be concluded that the filler content significantly interfered in the flexural strength and modulus of elasticity of the composites tested.

  10. Flexural-response of the McMurdo Ice Shelf to surface lake filling and drainage

    Science.gov (United States)

    Banwell, A. F.; MacAyeal, D. R.; Willis, I.; Macdonald, G. J.; Goodsell, B.

    2017-12-01

    Antarctic ice-shelf instability and break-up, as exhibited by the Larsen B ice shelf in 2002, remains one of the most difficult glaciological processes to observe directly. It is, however, vital to do so because ice-shelf breakup has the potential to influence the buttressing controls on inland ice discharge, and thus to affect sea level. Several mechanisms enabling Larsen B style breakup have previously been proposed, including the ability of surface lakes to introduce ice-shelf fractures when they fill and drain. During the austral summer of 2016/2017, we monitored the filling and draining of four surface lakes on the McMurdo Ice Shelf, Antarctica, and the effect of these processes on ice-shelf flexure. Water-depth data from pressure sensors reveal that two lakes filled to >2 m in depth and subsequently drained over multiple week timescales, which had a simultaneous effect on vertical ice deflection in the area. Differential GPS data from 12 receivers over three months show that vertical deflection varies as a function of distance from the maximum load change (i.e. at the lake centre). Using remote sensing techniques applied to both Landsat 8 and Worldview imagery, we also quantify the meltwater volume in these two lakes through the melt season, which, together with the vertical deflection data, are used to constrain key flexural parameter values in numerical models of ice-shelf flexure.

  11. Effect of the bur grit size on the flexural strength of a glass-ceramic

    Directory of Open Access Journals (Sweden)

    P. P. Kist

    Full Text Available Abstract The purpose of the present study was to determine the biaxial flexural strength (BFS of a CAD/CAM leucite reinforced glass-ceramic ground by diamond burs of different grit sizes and the influence of surface roughness on the BFS. For this, 104 plates were obtained from CAD/CAM ceramic blocks and divided into 4 groups (n = 26, according to bur grit size: extra-fine, fine, medium and coarse. Roughness parameters (Ra, RyMax were measured, and plates were kept dry for 7 days. The flexural test was carried out and BFS was calculated. Ra, RyMax and BFS data were subjected to analysis of variance and post-hoc test. Weibull analysis was used to compare characteristic strength and Weibull modulus. Regression analysis was performed for BFS vs. Ra and RyMax. When burs with coarse grit were used, higher surface roughness values were found, causing a negative effect on the ceramic BFS (117 MPa for extra-fine, and 83 MPa for coarse. Correlation (r between surface roughness and BFS was 0.78 for RyMax and 0.73 for Ra. Increases in diamond grit size have a significant negative effect on the BFS of leucite-reinforced glass-ceramics, suggesting that grinding of sintered glass-ceramic should be performed using burs with the finest grit possible in order to minimize internal surface flaws and maximize flexural strength.

  12. Trans fatty acids increase nitric oxide levels and pancreatic beta-cell necrosis in rats

    Directory of Open Access Journals (Sweden)

    Kusmiyati Tjahjono DK

    2013-04-01

    Full Text Available Background The prevalence of diabetes in Indonesia is increasing due to various factors, including life style changes such as trans fatty acid (TFA intake. High TFA intake is known to be related to blood lipid profile changes resulting in cardiovascular disorders. This study was to identify the effect of TFA on nitric oxide (NO production and on necrosis of pancreatic beta cells. Methods A study of randomized pre-test post–test design with control group. Thirty Sprague Dawley rats were divided into 3 groups, i.e. group K (control, group P1 receiving a diet with 5% TFA, and P2 receiving 10% TFA. The intervention was performed for 8 weeks. NO level and pancreatic beta-cell necrosis were analyzed using Pearson’s chi square test. Results After 4 weeks of treatment there was no change in NO levels in group K, but increased NO in P2 (2.6-3.8 ìM. At 8 weeks after treatment, NO levels in groups P1 and P2 increased to 2.6-3.4 ìM and 4.2-14.3 ìM, respectively, while in group K only 2 rats had increased NO levels of 2.8-2.9 ìM. With Pearson’s chi-square test, there was a signifant difference in the proportions of necrotic pancreatic beta cells after 4 weeks and 8 weeks (p=0.000. No necrosis of beta cells was found in group K, mild necrosis in group P1 (1-25% and moderate necrosis in group P2 (26-50%. Conclusion TFA consumption significantly increases NO levels in Sprague Dawley rats and also results in moderate grades of necrosis of pancreatic beta cells.

  13. Trans fatty acids increase nitric oxide levels and pancreatic beta-cell necrosis in rats

    Directory of Open Access Journals (Sweden)

    Kusmiyati Tjahjono DK

    2015-12-01

    Full Text Available BACKGROUND The prevalence of diabetes in Indonesia is increasing due to various factors, including life style changes such as trans fatty acid (TFA intake. High TFA intake is known to be related to blood lipid profile changes resulting in cardiovascular disorders. This study was to identify the effect of TFA on nitric oxide (NO production and on necrosis of pancreatic beta cells. METHODS A study of randomized pre-test post–test design with control group. Thirty Sprague Dawley rats were divided into 3 groups, i.e. group K (control, group P1 receiving a diet with 5% TFA, and P2 receiving 10% TFA. The intervention was performed for 8 weeks. NO level and pancreatic beta-cell necrosis were analyzed using Pearson’s chi square test. RESULTS After 4 weeks of treatment there was no change in NO levels in group K, but increased NO in P2 (2.6-3.8 ìM. At 8 weeks after treatment, NO levels in groups P1 and P2 increased to 2.6-3.4 ìM and 4.2-14.3 ìM, respectively, while in group K only 2 rats had increased NO levels of 2.8-2.9 ìM. With Pearson’s chi-square test, there was a signifant difference in the proportions of necrotic pancreatic beta cells after 4 weeks and 8 weeks (p= 0.000. No necrosis of beta cells was found in group K, mild necrosis in group P1 (1-25% and moderate necrosis in group P2 (26-50%. CONCLUSION TFA consumption significantly increases NO levels in Sprague Dawley rats and also results in moderate grades of necrosis of pancreatic beta cells

  14. Reversal of cerebral radiation necrosis with bevacizumab treatment in 17 Chinese patients

    Directory of Open Access Journals (Sweden)

    Wang Yang

    2012-08-01

    Full Text Available Abstract Background Bevacizumab has been suggested as a new treatment modality for cerebral radiation necrosis due to its ability to block the effects of vascular endothelial growth factor (VEGF in leakage-prone capillaries, though its use still remains controversial in clinical practice. Methods The use of bevacizumab in 17 patients with symptomatic cerebral radiation necrosis poorly controlled with dexamethasone steroid treatments was examined between March 2010 and January 2012. Bevacizumab therapy was administered for a minimum of two cycles (7.5 mg/kg, at two-week interval with a median of four bevacizumab injections. Changes in bi-dimensional measurements of the largest radiation necrosis lesions were observed by gadolinium-enhanced and T2-weighted magnetic resonance imaging (MRI. Additionally, dexamethasone dosage, Karnofsky performance status (KPS, adverse event occurrence and associated clinical outcomes were recorded for each patient. Results MRI analysis revealed that the average reduction was 54.9% and 48.4% in post-gadolinium and T2-weighted sequence analysis, respectively. Significant clinical neurological improvements were expressed in 10 patients according to KPS values. Dexamethasone reduction was achieved four weeks after initiation of bevacizumab in all patients, with four patients successfully discontinuing dexamethasone treatment. Mild to moderate bevacizumab-related adverse events, such as fatigue, proteinuria and hypertension were observed in three patients. Upon follow-up at 4 to 12 months, 10 patients showed clinical improvement, and 7 patient deaths occurred from tumor progression (5 patients, recurrent necrosis (1 patient, and uncontrolled necrosis-induced edema (1 patient. Conclusions These findings suggest bevacizumab as a promising treatment for cerebral radiation necrosis induced by common radiation therapies, including external beam radiotherapy (EBRT, stereotactic radiosurgery (SRS, and fractionated stereotactic

  15. Lymph node metastasis of carcinomas of transverse colon including flexures. Consideration of the extramesocolic lymph node stations.

    Science.gov (United States)

    Perrakis, Aristotelis; Weber, Klaus; Merkel, Susanne; Matzel, Klaus; Agaimy, Abbas; Gebbert, Carol; Hohenberger, Werner

    2014-10-01

    Complete mesocolic excision (CME) is nowadays state of the art in the treatment of colon cancer. In cases of carcinoma of transverse colon and of both flexures an extramesocolic lymph node metastasis can be found in the infrapancreatic lymph node region (ILR) and across the gastroepiploic arcade (GLR). These direct metastatic routes were not previously systematically considered. In order to validate our hypothesis of these direct metastatic pathways and to obtain evidence of our approach of including dissection of these areas as part of CME, we initiated a prospective study evaluating these lymph node regions during surgery. Forty-five consecutive patients with primary tumour manifestation in transverse colon and both flexures between May 2010 and January 2013 were prospectively analyzed. Patients were followed up for at least 6 months. Mode of surgery, histopathology, morbidity and mortality were evaluated. Twenty-six patients had a carcinoma of transverse colon, 16 patients one of hepatic flexure and four patients one of splenic flexure. The median lymph node yield was 40. Occurrence of lymph node metastasis in ILR was registered in five patients and in GLR in four patients. The mean lymph node ratio was 0.085. Postoperative complications occurred in nine patients, and postoperative mortality was 2 %. We were able to demonstrate this novel metastatic route of carcinomas of the transverse colon and of both flexures in ILR and GLR. These could be considered as regional lymph node regions and have to be included into surgery for cancer of the transverse colon including both flexures.

  16. Investigation on Failures of Composite Beam and Substrate Concrete due to Drying Shrinkage Property of Repair Materials

    Science.gov (United States)

    Pattnaik, Rashmi Ranjan

    2017-06-01

    A Finite Element Analysis (FEA) and an experimental study was conducted on composite beam of repair material and substrate concrete to investigate the failures of the composite beam due to drying shrinkage property of the repair materials. In FEA, the stress distribution in the composite beam due to two concentrate load and shrinkage of repair materials were investigated in addition to the deflected shape of the composite beam. The stress distributions and load deflection shapes of the finite element model were investigated to aid in analysis of the experimental findings. In the experimental findings, the mechanical properties such as compressive strength, split tensile strength, flexural strength, and load-deflection curves were studied in addition to slant shear bond strength, drying shrinkage and failure patterns of the composite beam specimens. Flexure test was conducted to simulate tensile stress at the interface between the repair material and substrate concrete. The results of FEA were used to analyze the experimental results. It was observed that the repair materials with low drying shrinkage are showing compatible failure in the flexure test of the composite beam and deform adequately in the load deflection curves. Also, the flexural strength of the composite beam with low drying shrinkage repair materials showed higher flexural strength as compared to the composite beams with higher drying shrinkage value of the repair materials even though the strength of those materials were more.

  17. MRI Findings of Pericardial Fat Necrosis: Case Report

    International Nuclear Information System (INIS)

    Lee, Hyo Hyeok; Ryu, Dae Shick; Jung, Sang Sig; Jung, Seung Mun; Choi, Soo Jung; Shin, Dae Hee

    2011-01-01

    Pericardial fat necrosis is an infrequent cause of acute chest pain and this can mimic acute myocardial infarction and acute pericarditis. We describe here a patient with the magnetic resonance imaging (MRI) findings of pericardial fat necrosis and this was correlated with the computed tomography (CT) findings. The MRI findings may be helpful for distinguishing pericardial fat necrosis from other causes of acute chest pain and from the fat-containing tumors in the cardiophrenic space of the anterior mediastinum.

  18. Translucent zirconia in the ceramic scenario for monolithic restorations: A flexural strength and translucency comparison test.

    Science.gov (United States)

    Carrabba, Michele; Keeling, Andrew J; Aziz, Aziz; Vichi, Alessandro; Fabian Fonzar, Riccardo; Wood, David; Ferrari, Marco

    2017-05-01

    To compare three different compositions of Yttria-Tetragonal Zirconia Polycrystal (Y-TZP) ceramic and a lithium disilicate ceramic in terms of flexural strength and translucency. Three zirconia materials of different composition and translucency, Aadva ST [ST], Aadva EI [EI] and Aadva NT [NT](GC Tech, Leuven, Belgium) were cut with a slow speed diamond saw into beams and tabs in order to obtain, after sintering, dimensions of 1.2×4.0×15.0mm and 15.0×15.0×1.0mm respectively. Blocks of IPS e.max CAD LT were cut and crystallized in the same shapes and dimensions and used as a reference group [LD]. Beams (n=15) were tested in a universal testing machine for three-point bending strength. Critical fracture load was recorded in N, flexural strength (σ in MPa), Weibull modulus (m) and Weibull characteristic strength (σ 0 in MPa) were then calculated. Tabs (n=10) were measured with a spectrophotometer equipped with an integrating sphere. Contrast Ratios were calculated as CR=Yb/Yw. SEM of thermally etched samples coupled with lineal line analysis (n=6) was used to measure the tested zirconia grain size. Data were statistically analyzed. Differences in translucency, flexural strength and grain size were found to be statistically significant. CR increased and flexural strength decreased in the following order ST(σ 1215±190MPa, CR 0.74±0.01)>EI(σ 983±182MPa, CR 0.69±0.01)>NT(σ 539±66MPa, CR 0.65±0.01)>LD (σ 377±39Mpa, CR 0.56±0.02). The average grain size was different for the three zirconia samples with NT(558±38nm)>ST(445±34nm)>EI(284±11nm). The zirconia composition heavily influenced both the flexural strength and the translucency. Different percentages of Yittria and Alumina result in new materials with intermediate properties in between the conventional zirconia and lithium disilicate. Clinical indications for Zirconia Aadva NT should be limited up to three-unit span bridges. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Paleobathymetry from 3-D flexural backstripping: Implementation and application to NW Australia and Liberia passive margins

    Science.gov (United States)

    Lovely, Peter; Chauvin, Benjamin; Brennan, Patrick; Laroche, Matt

    2015-04-01

    Understanding paleobathymetry is important to hydrocarbon explorationists, as it impacts depositional environments, reservoir quality, source rock preservation, hydrocarbon migration pathways, and paleo-stress. At long wavelengths (basin scale), bathymetry is controlled predominantly by isostatic compensation of vertical loads, which include sediment, water and spatial and temporal variations in the thickness and temperature of the crust and lithospheric mantle. Roberts, et al. (2003) present a workflow to account for these loads and derive paleobathymetry by 3-D flexural backstripping. However, to our knowledge, commercially packaged software for flexural backstripping is limited to two dimensions, and 3-D software is limited to Airy isostasy, which does not account for the elastic stiffness of the earth's crust and may, as a result, produce local error of 1km or more. We have developed a 3-D backstripping application that incorporates flexural isostasy, and is implemented in a workflow modeled after Roberts, et al. (2003). The application restores the isostatic components of basin geometry and bathymetry, and may account for the effects of sediment loading (isostasy & compaction), and rift-related subsidence (post- and syn-rift effects of homogeneous or depth-dependent pure-shear stretching models. Effects of dynamic topography, if quantifiable, may be prescribed as a bulk shift after backstripping. Implemented as a plug-in to Gocad, the application is accessible to a broad audience of geoscientists. The flexural isostasy implementation accounts for basin geometry and spatially heterogeneous layer thickness by discretizing each layer as a series of cylindrical loads of varying density and thickness at the nodes of a square grid. The isostatic effect of a single cylindrical load is provided by Brotchie & Silvester (1969) and the effect of multiple loads may be summed linearly. An iterative approach for calculating local water depth accounts for variations in

  20. The effect of zirconia on flexural strength of IPS Empress 2 ceramic

    Directory of Open Access Journals (Sweden)

    Kermanshah H

    2007-06-01

    Full Text Available Background and Aim: All ceramic, inlay-retained resin bonded fixed partial denture is a conservative method for replacement of missing teeth, because of minimal tooth reduction. The connector between the retainer and the pontic is the weak point of these bridges. Reinforcement of ceramic core will increase the clinical longevity. The aim of this study was to determine the effect of zirconia on flexural strength of IPS Empress 2 core ceramic.Materials and Methods: In this experimental in vitro study, twenty eight bar shape specimens (17´3.1´3.1 mm were made of four different materials: (1 Slip casting in-ceram alumina core (control group (2 Hot-pressed lithium disilicate core ceramic (IPS Empress 2 (3 IPS Empress 2 with cosmopost (zirconia post inserted longitudinally in the center of the bar (4 IPS Empress 2 with cosmopost (zirconia post inserted longitudinally in bottom of the bar. Specimens were subjected to three-point flexure loading with the span of 15mm, at a cross-head speed of 0.5 mm/min. Failure loads were recorded and analyzed using one-way ANOVA and Tomhane Post-hoc tests and p<0.05 was set as the level of significance. Fractured surfaces were then observed by scanning electron microscope (SEM. Four additional samples were made as the third group, and zirconia-IPS interface was observed by SEM before fracture.Results: Mean values and standard deviations of three point flexural strengths of groups 1 to 4, were: 378.4±44.6, 258.6±27.5, 144.3±51.7, 230±22.3 MPa respectively. All the groups were statistically different from each other (P<0.05, except groups 2 and 4. The flexural strengths of groups 2, 3, 4 were significantly lower than group 1. Group 3 had the lowest flexural strength. SEM analysis showed that the initiated cracks propagated in the interface of zirconia post and IPS Empress 2 ceramic.Conclusion: Based on the results of this study, inserting zirconia post (cosmopost in IPS Empress 2 ceramic does not reinforce all

  1. Identification of avascular necrosis in the dysplastic proximal femoral epiphysis

    International Nuclear Information System (INIS)

    Mandell, G.A.; Harcke, H.T.; MacKenzie, W.G.; Bassett, G.S.; Scott, C.I. Jr.; Wills, J.S.

    1989-01-01

    Bilateral radiographic irregularities and deformities of the proximal femoral epiphyses are features of both multiple epiphyseal dysplasia and bilateral idiopathic avascular necrosis. In the past these entities have been difficult to differentiate. This report documents radiographically the occurrence of avascular necrosis in 10 patients with multiple epiphyseal dysplasia by recognizing the superimposition of sclerosis and subchondral fissuring on pre-existing symmetrically irregular proximal femoral ossification centers. Scintigraphic (photopenia) or magnetic resonance (loss of signal) criteria of avascular necrosis confirm its added presence and help to establish an imaging scheme to identify avascular necrosis superimposed on multiple epiphyseal dysplasia. (orig.)

  2. Identification of avascular necrosis in the dysplastic proximal femoral epiphysis

    Energy Technology Data Exchange (ETDEWEB)

    Mandell, G A; Harcke, H T [Alfred I. duPont Inst., Wilmington, DE (USA). Dept. of Medical Imaging; MacKenzie, W G; Bassett, G S [Alfred I. duPont Inst., Wilmington, DE (USA). Dept. of Orthopaedics; Scott, Jr, C I [Alfred I. duPont Inst., Wilmington, DE (USA). Dept. of Genetics; Wills, J S [Medical Center of Delaware, Newark, DE (USA). Dept. of Radiology

    1989-07-01

    Bilateral radiographic irregularities and deformities of the proximal femoral epiphyses are features of both multiple epiphyseal dysplasia and bilateral idiopathic avascular necrosis. In the past these entities have been difficult to differentiate. This report documents radiographically the occurrence of avascular necrosis in 10 patients with multiple epiphyseal dysplasia by recognizing the superimposition of sclerosis and subchondral fissuring on pre-existing symmetrically irregular proximal femoral ossification centers. Scintigraphic (photopenia) or magnetic resonance (loss of signal) criteria of avascular necrosis confirm its added presence and help to establish an imaging scheme to identify avascular necrosis superimposed on multiple epiphyseal dysplasia. (orig.).

  3. Indomethacin induced avascular necrosis of head of femur

    Science.gov (United States)

    Prathapkumar, K; Smith, I; Attara, G

    2000-01-01

    Chemically induced avascular necrosis of bone is a well documented entity. Indomethacin is one of the causes of this condition but is often difficult to recognise. Review of the literature shows that only one case of indomethacin induced avascular necrosis has been reported in the English language between 1966 and the present.
The case of a young healthy man, who developed avascular necrosis of head of femur after prolonged administration of indomethacin, is reported here.


Keywords: indomethacin; avascular necrosis PMID:10964124

  4. One of the proposals to estimation of the active fault with the flexure structure

    Science.gov (United States)

    Kitada, N.; Takemura, K.

    2010-12-01

    In general, the recurrent interval investigation that uses the trench excavation survey etc. is done to the active fault survey. However, even if form of the search procedure of the active fault where the surface part is flexure structure is understood, it is difficult to understand the detailed activity situation. The active fault survey is done by the sedimentary environment of the investigation site, and an efficient search procedure is different. However, the recurrent interval of the fault with the flexure structure should devise it more. In the present study, two illustrations of the examination case with the active fault with the flexure structure. Osaka bay fault has the flexure structure, and the latest activity is not understood well though many reflection surveys have done. Then, flexure was stepped over and the drilling survey was carried out. It consists of the alluvium marine clay in the surface part compared the change in the amount of piling up by measuring at magnetostratigraphical measurement and a radio carbon age etc., and correlates between up side and down side homogeneous clay layer. As a result, the appearance with a greatly different inclination was confirmed between the boring of both who seemed that the same environments it though the correlation line was basically compared by the same inclination. When the alluvium piles up, such a change point is three times. The change was seen at the rate once every about 2000-3000 years and about 0.58m/ka when putting it together on the result of the age determination. The Uemachi fault is a fault in the south north that passes as for the central area of Osaka. The up side on the fault is modified by erosion and urban development, and one of the faults that a recurrent interval is cramped. Moreover, the surface part is flexure structure in this fault according to the reflection survey. To forecast a long term for the seismic design when the subway in this part was constructed, the drilling survey of

  5. Chlorpromazine inhibits tumour necrosis factor synthesis and cytotoxicity in vitro.

    Science.gov (United States)

    Zinetti, M; Galli, G; Demitri, M T; Fantuzzi, G; Minto, M; Ghezzi, P; Alzani, R; Cozzi, E; Fratelli, M

    1995-11-01

    Chlorpromazine (CPZ) has been previously shown to protect against endotoxin [lipopolysaccharide (LPS)] lethality and inhibit the release of tumour necrosis factor in vivo. We investigated at the cellular level whether this was due to direct inhibition of tumour necrosis factor-alpha (TNF-alpha) synthesis, using LPS-stimulated THP-1 human monocytic leukemia cells. We also studied the effect of CPZ on human TNF-alpha action by assessing TNF-alpha cytotoxicity on mouse fibrosarcoma L929 cells. CPZ (1-100 microM) inhibited TNF-alpha production in THP-1 cells in a dose dependent manner by a maximum of 80%. This effect was comparable to that of two well-known inhibitory drugs, dexamethasone and cyclicAMP. Inhibition was also evident at the mRNA level. On the other hand CPZ (10-25 microM) also inhibited TNF-alpha activity: in fact it reduced the cytotoxicity of TNF-alpha on L929 cells (EC50 was increased four times) and could provide protection even as a post-treatment. CPZ inhibited TNF-induced apoptosis in L929 cells, as detected by analysis of nuclear morphology. However, since we showed that apoptosis was very limited, and was not the main mode of cell death in our conditions, this could not explain the overall protection. Since CPZ did not interfere with either the oligomerization state of TNF-alpha or its receptor binding, our data suggest that it reduced cytotoxicity by inhibiting some steps in the TNF-alpha signalling pathways.

  6. Determination of the elastic and stiffness characteristics of cross-laminated timber plates from flexural wave velocity measurements

    Science.gov (United States)

    Santoni, Andrea; Schoenwald, Stefan; Van Damme, Bart; Fausti, Patrizio

    2017-07-01

    Cross-laminated timber (CLT) is an engineered wood with good structural properties and it is also economically competitive with the traditional building construction materials. However, due to its low volume density combined with its high stiffness, it does not provide sufficient sound insulation, thus it is necessary to develop specific acoustic treatments in order to increase the noise reduction performance. The material's mechanical properties are required as input data to perform the vibro-acoustic analyses necessary during the design process. In this paper the elastic constants of a CLT plate are derived by fitting the real component of the experimental flexural wave velocity with Mindlin's dispersion relation for thick plates, neglecting the influence of the plate's size and boundary conditions. Furthermore, its apparent elastic and stiffness properties are derived from the same set of experimental data, for the plate considered to be thin. Under this latter assumption the orthotropic behaviour of an equivalent thin CLT plate is described by using an elliptic model and verified with experimental results.

  7. Impact strength and flexural properties enhancement of methacrylate silane treated oil palm mesocarp fiber reinforced biodegradable hybrid composites.

    Science.gov (United States)

    Eng, Chern Chiet; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Ariffin, Hidayah; Yunus, Wan Md Zin Wan

    2014-01-01

    Natural fiber as reinforcement filler in polymer composites is an attractive approach due to being fully biodegradable and cheap. However, incompatibility between hydrophilic natural fiber and hydrophobic polymer matrix restricts the application. The current studies focus on the effects of incorporation of silane treated OPMF into polylactic acid (PLA)/polycaprolactone (PCL)/nanoclay/OPMF hybrid composites. The composites were prepared by melt blending technique and characterize the composites with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR spectra indicated that peak shifting occurs when silane treated OPMF was incorporated into hybrid composites. Based on mechanical properties results, incorporation of silane treated OPMF enhances the mechanical properties of unmodified OPMF hybrid composites with the enhancement of flexural and impact strength being 17.60% and 48.43%, respectively, at 10% fiber loading. TGA thermogram shows that incorporation of silane treated OPMF did not show increment in thermal properties of hybrid composites. SEM micrographs revealed that silane treated OPMF hybrid composites show good fiber/matrix adhesion as fiber is still embedded in the matrix and no cavity is present on the surface. Water absorption test shows that addition of less hydrophilic silane treated OPMF successfully reduces the water uptake of hybrid composites.

  8. Influence of the tip mass and position on the AFM cantilever dynamics: Coupling between bending, torsion and flexural modes

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtari-Nezhad, F. [Department of Mechanical Engineering, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Saidi, A.R., E-mail: saidi@mail.uk.ac.ir [Department of Mechanical Engineering, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Ziaei-Rad, S. [Department of Mechanical Engineering, Isfahan University of Technology (IUT), Isfahan 84156-83111 (Iran, Islamic Republic of)

    2009-08-15

    The effects of the geometrical asymmetric related to tip position as a concentrated mass, on the sensitivity of all three vibration modes, lateral excitation (LE), torsional resonance (TR) and vertical excitation (VE), of an atomic force microscopy (AFM) microcantilever have been analyzed. The effects of the tip mass and its position are studied to report the novel results to estimating the vibration behavior of AFM such as resonance frequency and amplitude of the microcantilever. In this way, to achieve more accurate results, the coupled motion in all three modes is considered. In particular, it is investigated that performing the coupled motion in analysis of AFM microcantilever is almost necessary. It is shown that the tip mass and its position have significant effects on vibrational responses. The results show that considering the tip mass decreases the resonance frequencies particularly on high-order modes. However, dislocating of tip position has an inverse effect that causes an increase in the resonance frequencies. In addition, it has been shown that the amplitude of the AFM microcantilever is affected by the influences of tip and its position. These effects are caused by the interaction between flexural and torsional motion due to the moment of inertia of the tip mass.

  9. Influence of the tip mass and position on the AFM cantilever dynamics: Coupling between bending, torsion and flexural modes

    International Nuclear Information System (INIS)

    Mokhtari-Nezhad, F.; Saidi, A.R.; Ziaei-Rad, S.

    2009-01-01

    The effects of the geometrical asymmetric related to tip position as a concentrated mass, on the sensitivity of all three vibration modes, lateral excitation (LE), torsional resonance (TR) and vertical excitation (VE), of an atomic force microscopy (AFM) microcantilever have been analyzed. The effects of the tip mass and its position are studied to report the novel results to estimating the vibration behavior of AFM such as resonance frequency and amplitude of the microcantilever. In this way, to achieve more accurate results, the coupled motion in all three modes is considered. In particular, it is investigated that performing the coupled motion in analysis of AFM microcantilever is almost necessary. It is shown that the tip mass and its position have significant effects on vibrational responses. The results show that considering the tip mass decreases the resonance frequencies particularly on high-order modes. However, dislocating of tip position has an inverse effect that causes an increase in the resonance frequencies. In addition, it has been shown that the amplitude of the AFM microcantilever is affected by the influences of tip and its position. These effects are caused by the interaction between flexural and torsional motion due to the moment of inertia of the tip mass.

  10. The Investigation on Flexural Toughness of Partially Steel Fiber Reinforced Concrete Immersed by Simulated Sea-Water

    Directory of Open Access Journals (Sweden)

    Feng GAO

    2017-11-01

    Full Text Available In order to investigate the corrosive resistance of partially steel fiber reinforced concrete (PSFRC, the flexural toughness experiment of nine specimens subjected to corrosion by alternating wet and dry cycles in a simulated marine environment were conducted, which aims at investigating the effect of corrosion time, steel fiber volume fraction and SFRC thickness on PSFRC toughness. The experimental results showed that both the mechanical and ductile characteristics of PSFRC got worse due to corrosion even if increasing the steel fiber volume. Additionally, the effect of steel fiber content on the toughness and ultimate load are greater than PSFRC thickness (t. The increase of 56.6% and 171% could be obtained in the mean ultimate load and I10 if the increase of steel fiber volume is from 0.5 % to 2.0%, respectively. This paper could offer a reference to the application of PSFRC in sea-water environment.DOI: http://dx.doi.org/10.5755/j01.ms.23.4.17049

  11. The role of nonlinear torsional contributions on the stability of flexural-torsional oscillations of open-cross section beams

    Science.gov (United States)

    Di Egidio, Angelo; Contento, Alessandro; Vestroni, Fabrizio

    2015-12-01

    An open-cross section thin-walled beam model, already developed by the authors, has been conveniently simplified while maintaining the capacity of accounting for the significant nonlinear warping effects. For a technical range of geometrical and mechanical characteristics of the beam, the response is characterized by the torsional curvature prevailing over the flexural ones. A Galerkin discretization is performed by using a suitable expansion of displacements based on shape functions. The attention is focused on the dynamic response of the beam to a harmonic force, applied at the free end of the cantilever beam. The excitation is directed along the symmetry axis of the beam section. The stability of the one-component oscillations has been investigated using the analytical model, showing the importance of the internal resonances due to the nonlinear warping coupling terms. Comparison with the results provided by a computational finite element model has been performed. The good agreement among the results of the analytical and the computational models confirms the effectiveness of the simplified model of a nonlinear open-cross section thin-walled beam and overall the important role of the warping and of the torsional elongation in the study of the one-component dynamic oscillations and their stability.

  12. Avascular necrosis of the femoral head

    International Nuclear Information System (INIS)

    Kokubo, Takashi; Takatori, Yoshio; Ninomiya, Setsuo; Sasaki, Yasuhito

    1993-01-01

    Magnetic resonance (MR) images and conventional radiographs were compared in 142 hips with avascular necrosis, and a staging system for the disease based on MR imaging was developed. MR images were classified into three patterns: a band of low signal intensity (class I); an area of low signal intensity with internal spot(s) of high signal (class II); and an area of low signal intensity without internal spots of high signal (class III). Most MR class I lesions were in radiographic stage I (normal) or II (sclerotic or cystic changes without collapse). Most MR class II lesions were in radiographic stage III (segmental collapse), and most MR class III lesions were in stage III or IV (secondary degenerative changes). The MR image classification was closely correlated with radiographic staging (p<0.01, using χ square test). We considered that this classification closely reflected the different stages of the disease according to the histopathology of the bone marrow. (author)

  13. Rin4 causes hybrid necrosis and race-specific resistance in an interspecific lettuce hybrid.

    Science.gov (United States)

    Jeuken, Marieke J W; Zhang, Ningwen W; McHale, Leah K; Pelgrom, Koen; den Boer, Erik; Lindhout, Pim; Michelmore, Richard W; Visser, Richard G F; Niks, Rients E

    2009-10-01

    Some inter- and intraspecific crosses may result in reduced viability or sterility in the offspring, often due to genetic incompatibilities resulting from interactions between two or more loci. Hybrid necrosis is a postzygotic genetic incompatibility that is phenotypically manifested as necrotic lesions on the plant. We observed hybrid necrosis in interspecific lettuce (Lactuca sativa and Lactuca saligna) hybrids that correlated with resistance to downy mildew. Segregation analysis revealed a specific allelic combination at two interacting loci to be responsible. The allelic interaction had two consequences: (1) a quantitative temperature-dependent autoimmunity reaction leading to necrotic lesions, lethality, and quantitative resistance to an otherwise virulent race of Bremia lactucae; and (2) a qualitative temperature-independent race-specific resistance to an avirulent race of B. lactucae. We demonstrated by transient expression and silencing experiments that one of the two interacting genes was Rin4. In Arabidopsis thaliana, RIN4 is known to interact with multiple R gene products, and their interactions result in hypersensitive resistance to Pseudomonas syringae. Site-directed mutation studies on the necrosis-eliciting allele of Rin4 in lettuce showed that three residues were critical for hybrid necrosis.

  14. Effect of microwave postpolymerization treatment on residual monomer content and the flexural strength of autopolymerizing reline resin

    Directory of Open Access Journals (Sweden)

    Patil Padmakar

    2009-01-01

    Full Text Available Background : Microwave postpolymerization has been suggested as a method to improve the flexural strength of an autopolymerizing denture reline resin. However, the effect of microwave postpolymerization on the residual monomer content and its influence on flexural strength have not been investigated. Objectives : This study analyzed the effect of microwave postpolymerization on the residual monomer content and its influence on the flexural strength of an autopolymerizing reline resin (Denture Liner. Materials and Methods : A total of 70 specimens (64 Χ 10 Χ 3.3 mm were polymerized according to the manufacturer′s instructions and divided into 7 groups (n = 10. Control group specimens were not subjectedto any further processing. Before testing, the specimens were subjected to postpolymerization in a microwave oven using different power (550 and 650 W and time (3, 4, and 5 min settings. Two specimens of each group were then manually ground into fine powder and samples extracted from the specimens using reflux method. The samples were then subjected to gas chromatography for residual monomer determination in area%. Eight specimens were subjected to a three-point bending device with a span of 50 mm and crosshead speed of 5 mm/min, and the flexural strength was determined in MPa. Data analyses included Student′s t-test and one-way analysis of variance. Results : For the Denture Liner reline resin, the residual monomer content decreased and the flexural strength increased significantly with the application of microwave irradiation using different time/power combinations. The specimens with the lowest residual monomer content were the similar specimens which presented with the highest flexural strength. Conclusion : Microwave postpolymerization irradiation can be an effective method for increasing the flexural strength of denture liner (at 650 W for 5 min by reducing the residual monomer content by further polymerization at free radical sites.

  15. Avascular necrosis of bone following renal transplantation | Naiker ...

    African Journals Online (AJOL)

    Alcohol conswnption and radiological evidence of osteoporosis were more prevalent in the avascular necrosis group (42,8% v. 29,0% and 28,5% v. 7,2% respectively). Avascular necrosis did not correlate with age, sex, renal function at 1 year or severe secondary hyperparathyroidism. This study suggests that corticosteroid ...

  16. Severe glandular tularemia in a patient treated with anti-tumour necrosis factor for psoriatic arthritis.

    Science.gov (United States)

    Calin, Ruxandra; Caumes, Eric; Reibel, Florence; Ali Mohamed, Anzime; Brossier, Florence; Foltz, Violaine; Boussouar, Samia; Fautrel, Bruno; Maurin, Max; Katlama, Christine; Pourcher, Valérie

    2017-07-01

    A case of severe glandular tularemia in a patient receiving anti-tumour necrosis factor (TNF) therapy is reported here. The patient required prolonged treatment with doxycycline-ciprofloxacin due to early relapse after ciprofloxacin was stopped. Tularemia may have a more severe course in patients receiving anti-TNF. This may thus be an indication for more aggressive treatment. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  17. Skin Necrosis from Intra-articular Hyaluronic Acid Injection.

    Science.gov (United States)

    Kim, Whan B; Alhusayen, Raed O

    2015-01-01

    Tissue necrosis is a rare yet potentially serious complication of intra-articular (IA) hyaluronic acid (HA) injections for treatment of knee osteoarthritis. To report a case of a patient with cutaneous necrosis after IA HA injection for treatment of knee osteoarthritis, presenting as a livedoid violaceous patch on the right knee. We report a case of cutaneous necrosis as a rare complication of IA HA injection for treatment of knee osteoarthritis. A literature review was undertaken of similar cases. Use of HA IA injections in the treatment of osteoarthritis can result in similar skin necrosis at uncommon anatomic locations corresponding to the site of HA injection. Although tissue necrosis is a rare complication, physicians need to be aware of this possibility as a complication of HA IA injections in the treatment of osteoarthritis and should be mindful of potential treatment options to manage this adverse event. © 2014 Canadian Dermatology Association.

  18. NecroQuant: quantitative assessment of radiological necrosis

    Science.gov (United States)

    Hwang, Darryl H.; Mohamed, Passant; Varghese, Bino A.; Cen, Steven Y.; Duddalwar, Vinay

    2017-11-01

    Clinicians can now objectively quantify tumor necrosis by Hounsfield units and enhancement characteristics from multiphase contrast enhanced CT imaging. NecroQuant has been designed to work as part of a radiomics pipelines. The software is a departure from the conventional qualitative assessment of tumor necrosis, as it provides the user (radiologists and researchers) a simple interface to precisely and interactively define and measure necrosis in contrast-enhanced CT images. Although, the software is tested here on renal masses, it can be re-configured to assess tumor necrosis across variety of tumors from different body sites, providing a generalized, open, portable, and extensible quantitative analysis platform that is widely applicable across cancer types to quantify tumor necrosis.

  19. Atraumatic Pantalar Avascular Necrosis in a Patient With Alcohol Dependence.

    Science.gov (United States)

    Callachand, Fayaz; Milligan, David; Wilson, Alistair

    2016-01-01

    In the United States, an estimated 10,000 to 20,000 new cases of avascular necrosis are diagnosed each year. We present an unusual case of atraumatic avascular necrosis with widespread hindfoot and midfoot involvement. A 62-year-old female with a history of alcohol dependence and smoking, who had previously been treated for avascular necrosis of the knee, presented with right-sided foot pain and difficulty weightbearing. Imaging studies revealed extensive avascular necrosis of the hindfoot and midfoot, which precluded simple surgical intervention. The patient was followed up for 18 months. In the last 8 months of the 18-month period, the patient managed her symptoms using an ankle-foot orthosis. A diagnosis of avascular necrosis should be considered in patients with atraumatic foot and ankle pain, especially in the presence of risk factors such as alcohol excess and smoking. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  20. Incorporation of the stress concentration slots into the flexures for a high-performance microaccelerometer

    International Nuclear Information System (INIS)

    Zhao Yulong; Sun Lu; Liu Yan; Wang Weizhong; Tian Bian

    2012-01-01

    Presented in this paper is a development of a high-performance piezoresistive microaccelerometer based on the slot etching in the quad flexures for the vibration detection of high speed spindle. The proposed structure consists of a proof mass supported by four thin flexures with slots etched in the middle. Boron diffused piezoresistors located near the stress concentration regions are used for sensing the localized stress resulting from the incorporation of the slots into the flexures. Theoretical analysis and finite element analysis show satisfactory results of an improved sensitivity and favorable natural frequency higher than 10 kHz, conforming to the initial design requirements. The microfabrication techniques are described to prototype the two accelerometer chips, one with slots and the other one without slots. The tested microaccelerometers with 3 V DC power supply show an average sensitivity of 0.424 mV/g normal to the proof mass plane, increased by 60.6% than the ones without slots. An average transverse sensitivity is found to be 9.2 μV/g along X axis and 14.2 μV/g along Y axis, either of which is less than 3.5% of prime-axis sensitivity. Concerning the resonant frequency, dynamic experiment shows about 12.46 kHz and is available for the proposed design with a tiny loss of 3.5% compared with the quad-beam design. When taking the product of sensitivity and natural frequency as judgment criteria, an inspiring increase by 28.6% of the figure of merit is accomplished for the proposed accelerometer. Overall, the findings of this study confirm the feasibility of incorporating slots into the conventional configurations to improve the sensor sensitivity while maintaining a comparatively high natural frequency.

  1. Stress optimization of leaf-spring crossed flexure pivots for an active Gurney flap mechanism

    Science.gov (United States)

    Freire Gómez, Jon; Booker, Julian D.; Mellor, Phil H.

    2015-04-01

    The EU's Green Rotorcraft programme is pursuing the development of a functional and airworthy Active Gurney Flap (AGF) for a full-scale helicopter rotor blade. Interest in the development of this `smart adaptive rotor blade' technology lies in its potential to provide a number of aerodynamic benefits, which would in turn translate into a reduction in fuel consumption and noise levels. The AGF mechanism selected employs leaf-spring crossed flexure pivots. These provide important advantages over bearings as they are not susceptible to seizing and do not require maintenance (i.e. lubrication or cleaning). A baseline design of this mechanism was successfully tested both in a fatigue rig and in a 2D wind tunnel environment at flight-representative deployment schedules. For full validation, a flight test would also be required. However, the severity of the in-flight loading conditions would likely compromise the mechanical integrity of the pivots' leaf-springs in their current form. This paper investigates the scope for stress reduction through three-dimensional shape optimization of the leaf-springs of a generic crossed flexure pivot. To this end, a procedure combining a linear strain energy formulation, a parametric leaf-spring profile definition and a series of optimization algorithms is employed. The resulting optimized leaf-springs are proven to be not only independent of the angular rotation at which the pivot operates, but also linearly scalable to leaf-springs of any length, minimum thickness and width. Validated using non-linear finite element analysis, the results show very significant stress reductions relative to pivots with constant cross section leaf-springs, of up to as much as 30% for the specific pivot configuration employed in the AGF mechanism. It is concluded that shape optimization offers great potential for reducing stress in crossed flexure pivots and, consequently, for extending their fatigue life and/or rotational range.

  2. Lithospheric flexure beneath the Freyja Montes Foredeep, Venus: Constraints on lithospheric thermal gradient and heat flow

    International Nuclear Information System (INIS)

    Solomon, S.C.; Head, J.W.

    1990-01-01

    Analysis of Venera 15 and 16 radar images and topographic data from the Freyja Montes region on Venus suggest that this mountain belt formed as a result of a sequence of underthrusts of the lithosphere of the North Polar Plains beneath the highlands of Ishtar Terra. The Freyja Montes deformation zone consists, south to north, of a linear orogenic belt, an adjacent plateau, a steep scarp separating the plateau from the North Polar Plains, a linear depression at the base of the scarp, and an outer rise. The topographic profile of the depression and outer rise are remarkably similar to that of a foreland deep and rise formed by the flexure of the underthrusting plate beneath a terrestrial mountain range. The authors test the lithospheric flexure hypothesis and they estimate the effective thickness T e of the elastic lithosphere of the underthrusting portion of the North Polar Plains by fitting individual topographic profiles to deflection curves for a broken elastic plate. The theoretical curves fit the observed topographic profiles to within measurement error for values of flexural rigidity D in the range (0.8-3) x 10 22 N m, equivalent to T e in the range 11-18 km. Under the assumption that the base of the mechanical lithosphere is limited by the creep strength of olivine, the mean lithospheric thermal gradient is 14-23 K/km. That the inferred thermal gradient is similar to the value expected for the global mean gradient on the basis of scaling from Earth provides support for the hypothesis that simple conduction dominates lithospheric heat transport on Venus relative to lithospheric recycling and volcanism

  3. Improvement of cooldown time of LSF9599 flexure-bearing SADA cooler

    Science.gov (United States)

    Mullié, Jeroen; vd Groep, Willem; Bruins, Peter; Benschop, Tonny; de Koning, Arjan; Dam, Jacques

    2006-05-01

    Thales Cryogenics has presented the LSF 9599 SADA II flexure cooler in 2005. Based on Thales' well-known moving magnet flexure technology, the LSF 9599 complies with the SADA II specification with respect to performance, envelope and mass. Being the first manufacturer offering a full flexure-bearing supported cooler that fits within the SADA II envelope, Thales Cryogenics has been selected in several new (military) programs with their LSF coolers. For many of these new programs, the cooldown time requirements are more stringent than in the past, whereas at the same time size, complexity and thus thermal mass of the infrared sensor tends to increase. In order to respond to the need created by the combination of these trends, Thales Cryogenics started a development program to optimize cryogenic performance of the LSF 9599 cooler. The main goal for the development program is to reduce the cooldown time, while maintaining the SADA II compatible interface, and maintaining the robustness and proven reliability of the cooler. Within these constraints, the regenerator was further optimized using among others the experience with mixed-gauze regenerators obtained from our pulse tube research. Using the mixed gauze approach, the heat storage capacity of the regenerator is adapted as a function of the temperature profile over the regenerator, thus giving the optimum balance between heat storage capacity and pressure drop. A novel way of constructing the regenerator further decreases shuttle heat losses and other thermal losses in the regenerator. This paper describes the first results of the trade-offs and gives an overview of impact on cooldown times and efficiency figures achieved after the regenerator and displacer optimization.

  4. Skin Flap Necrosis After Mastectomy With Reconstruction: A Prospective Study.

    Science.gov (United States)

    Matsen, Cindy B; Mehrara, Babak; Eaton, Anne; Capko, Deborah; Berg, Anastasia; Stempel, Michelle; Van Zee, Kimberly J; Pusic, Andrea; King, Tari A; Cody, Hiram S; Pilewskie, Melissa; Cordeiro, Peter; Sclafani, Lisa; Plitas, George; Gemignani, Mary L; Disa, Joseph; El-Tamer, Mahmoud; Morrow, Monica

    2016-01-01

    Rates of mastectomy with immediate reconstruction are rising. Skin flap necrosis after this procedure is a recognized complication that can have an impact on cosmetic outcomes and patient satisfaction, and in worst cases can potentially delay adjuvant therapies. Many retrospective studies of this complication have identified variable event rates and inconsistent associated factors. A prospective study was designed to capture the rate of skin flap necrosis as well as pre-, intra-, and postoperative variables, with follow-up assessment to 8 weeks postoperatively. Uni- and multivariate analyses were performed for factors associated with skin flap necrosis. Of 606 consecutive procedures, 85 (14 %) had some level of skin flap necrosis: 46 mild (8 %), 6 moderate (1 %), 31 severe (5 %), and 2 uncategorized (0.3 %). Univariate analysis for any necrosis showed smoking, history of breast augmentation, nipple-sparing mastectomy, and time from incision to specimen removal to be significant. In multivariate models, nipple-sparing, time from incision to specimen removal, sharp dissection, and previous breast reduction were significant for any necrosis. Univariate analysis of only moderate or severe necrosis showed body mass index, diabetes, nipple-sparing mastectomy, specimen size, and expander size to be significant. Multivariate analysis showed nipple-sparing mastectomy and specimen size to be significant. Nipple-sparing mastectomy was associated with higher rates of necrosis at every level of severity. Rates of skin flap necrosis are likely higher than reported in retrospective series. Modifiable technical variables have limited the impact on rates of necrosis. Patients with multiple risk factors should be counseled about the risks, especially if they are contemplating nipple-sparing mastectomy.

  5. Effect of the bur grit size on the flexural strength of a glass-ceramic

    OpenAIRE

    Kist, P. P.; Aurélio, I. L.; Amaral, M.; May, L. G.

    2016-01-01

    Abstract The purpose of the present study was to determine the biaxial flexural strength (BFS) of a CAD/CAM leucite reinforced glass-ceramic ground by diamond burs of different grit sizes and the influence of surface roughness on the BFS. For this, 104 plates were obtained from CAD/CAM ceramic blocks and divided into 4 groups (n = 26), according to bur grit size: extra-fine, fine, medium and coarse. Roughness parameters (Ra, RyMax) were measured, and plates were kept dry for 7 days. The flexu...

  6. Analysis of Flexural Fatigue Strength of Self Compacting Fibre Reinforced Concrete Beams

    Science.gov (United States)

    Murali, G.; Sudar Celestina, J. P. Arul; Subhashini, N.; Vigneshwari, M.

    2017-07-01

    This study presents the extensive statistical investigation ofvariations in flexural fatigue life of self-compacting Fibrous Concrete (FC) beams. For this purpose, the experimental data of earlier researchers were examined by two parameter Weibull distribution.Two methods namely Graphical and moment wereused to analyse the variations in experimental data and the results have been presented in the form of probability of survival. The Weibull parameters values obtained from graphical and method of moments are precise. At 0.7 stress level, the fatigue life shows 59861 cyclesfor areliability of 90%.

  7. Woven Hybrid Composites - Tensile and Flexural Properties of Jute Mat Fibres with Epoxy Composites

    Science.gov (United States)

    Gopal, P.; Bupesh Raja, V. K.; Chandrasekaran, M.; Dhanasekaran, C.

    2017-03-01

    The jute mat fibers are fabricated with several layers of fiber with opposite orientation in addition with coconut shell powder and resins. In current trends, metallic components are replaced by natural fibers because of the inherent properties such as light in weight, easy to fabricate, less cost and easy availability. This material has high strength and withstands the load. In this investigation the plates are made without stitching the fiber. The result of tensile strength and flexural strength are compared with nano material (coconut shell powder).

  8. Strength characterization of tubular ceramic materials by flexure of semi-cylindrical specimens

    DEFF Research Database (Denmark)

    Kwok, Kawai; Kiesel, Lutz; Frandsen, Henrik Lund

    2014-01-01

    Mechanical strength at elevated temperatures and operating atmospheres needs to be characterized during development of tubular ceramic components for advanced energy technologies. Typical procedures are time-consuming because a large number of tests are required for a reliable statistical strength...... characterization and every specimen has to be subjected to the process conditions individually. This paper presents an efficient strength characterization methodology for tubular ceramics. The methodology employs flexure of semi-cylindrical specimens as the strength test and implements the tests within a facility...... conducted on oxygen transport membrane materials at room temperature and 850°C....

  9. Extensional Fault Evolution and its Flexural Isostatic Response During Iberia-Newfoundland Rifted Margin Formation

    Science.gov (United States)

    Gómez-Romeu, J.; Kusznir, N.; Manatschal, G.; Roberts, A.

    2017-12-01

    During the formation of magma-poor rifted margins, upper lithosphere thinning and stretching is achieved by extensional faulting, however, there is still debate and uncertainty how faults evolve during rifting leading to breakup. Seismic data provides an image of the present-day structural and stratigraphic configuration and thus initial fault geometry is unknown. To understand the geometric evolution of extensional faults at rifted margins it is extremely important to also consider the flexural response of the lithosphere produced by fault displacement resulting in footwall uplift and hangingwall subsidence. We investigate how the flexural isostatic response to extensional faulting controls the structural development of rifted margins. To achieve our aim, we use a kinematic forward model (RIFTER) which incorporates the flexural isostatic response to extensional faulting, crustal thinning, lithosphere thermal loads, sedimentation and erosion. Inputs for RIFTER are derived from seismic reflection interpretation and outputs of RIFTER are the prediction of the structural and stratigraphic consequences of recursive sequential faulting and sedimentation. Using RIFTER we model the simultaneous tectonic development of the Iberia-Newfoundland conjugate rifted margins along the ISE01-SCREECH1 and TGS/LG12-SCREECH2 seismic lines. We quantitatively test and calibrate the model against observed target data restored to breakup time. Two quantitative methods are used to obtain this target data: (i) gravity anomaly inversion which predicts Moho depth and continental lithosphere thinning and (ii) reverse post-rift subsidence modelling to give water and Moho depths at breakup time. We show that extensional faulting occurs on steep ( 60°) normal faults in both proximal and distal parts of rifted margins. Extensional faults together with their flexural isostatic response produce not only sub-horizontal exhumed footwall surfaces (i.e. the rolling hinge model) and highly rotated (60

  10. Control of the long period grating spectrum through low frequency flexural acoustic waves

    International Nuclear Information System (INIS)

    Oliveira, Roberson A; Possetti, Gustavo R C; Kamikawachi, Ricardo C; Fabris, José L; Muller, Marcia; Pohl, Alexandre A P; Marques, Carlos A F; Nogueira, Rogério N; Neves, Paulo T Jr; Cook, Kevin; Canning, John; Bavastri, C

    2011-01-01

    We have shown experimental results of the excitation of long period fiber gratings by means of flexural acoustic waves with a wavelength larger than the grating period, validated by numerical simulations. The effect of the acoustic wave on the grating is modeled with the method of assumed modes, which delivers the strain field inside the grating, then used as the input to the transfer matrix method, needed for calculating the grating spectrum. The experimental and numerical results are found to be in good agreement, even though only the strain-optic effects are taken into account

  11. Skull Flexure from Blast Waves: A Mechanism for Brain Injury with Implications for Helmet Design

    Energy Technology Data Exchange (ETDEWEB)

    Moss, W C; King, M J; Blackman, E G

    2009-04-30

    Traumatic brain injury [TBI] has become a signature injury of current military conflicts, with debilitating, costly, and long-lasting effects. Although mechanisms by which head impacts cause TBI have been well-researched, the mechanisms by which blasts cause TBI are not understood. From numerical hydrodynamic simulations, we have discovered that non-lethal blasts can induce sufficient skull flexure to generate potentially damaging loads in the brain, even without a head impact. The possibility that this mechanism may contribute to TBI has implications for injury diagnosis and armor design.

  12. Distribution of Subsurface Flexure zone caused by Uemachi Fault, Japan and its activity

    Science.gov (United States)

    Kitada, N.; Inoue, N.; Takemura, K.; Ito, H.; Mitamura, M.

    2012-12-01

    In Osaka, Uemachi Fault is one of the famous active faults. It across the center of Osaka and lies in N-S direction mainly and is more than 40 km in length. The faults bound sedimentary basins, where thick sedimentary deposits of the Pliocene-Quaternary Osaka Group have accumulated. The deposits consist primarily of sand and marine and non-marine clay, and the clay layers are key markers for the interpretation of glacial and interglacial cycles. In this study, we estimate the width of the flexure zone using a geotechnical borehole database. GI database collects more than 40,000 boreholes and includes both geological information and soil properties around Osaka by the Geo-database Information Committee of Kansai Area. Our results indicate that the deformation associated with the flexure zone is distributed primarily along the splay fault (NE-SW) and not along the main fault, suggesting that the splay fault might be the primary fault at present. We first examined the borehole data along the seismic reflection line and then considered the surrounding area. An Upper Pleistocene marine clay (Ma12) is a good indicator of the flexure zone. We constructed many cross sections in and around the fault zone and classified the deformation form into three categories around the flexure zone. The results of this study allowed us to map the distribution of folding in a zone in the west of the Osaka area. Folding can be classified into three types: (1) Ma12 folding, (2) Ma12 folding that does not continue toward the hanging wall, and (3) folding or displacement of old marine clay. These folding zone trends are N-W strike however these trace are serpentine. These folding zone information are not in worth to estimate the source fault, however these zone will be more serious damaged when the earthquake occurred. Our result agrees well with the average displacement speed of about 0.4 m/ka that was derived by the Headquarters for Earthquake Research Promotion of the Ministry of Education

  13. Behaviour of partially composite precast concrete sandwich panels under flexural and axial loads

    Science.gov (United States)

    Tomlinson, Douglas George

    Precast concrete sandwich panels are commonly used on building exteriors. They are typically composed of two concrete wythes that surround rigid insulation. They are advantageous as they provide both structural and thermal resistance. The structural response of sandwich panels is heavily influenced by shear connectors that link the wythes together. This thesis presents a study on partially composite non-prestressed precast concrete wall panels. Nine flexure tests were conducted on a wall design incorporating 'floating' concrete studs and Glass Fibre Reinforced Polymer (GFRP) connectors. The studs encapsulate and stiffen the connectors, reducing shear deformations. Ultimate loads increased from 58 to 80% that of a composite section as the connectors' reinforcement ratio increased from 2.6 to 9.8%. This design was optimized by reinforcing the studs and integrating them with the structural wythe; new connectors composed of angled steel or Basalt-FRP (BFRP) were used. The load-slip response of the new connector design was studied through 38 double shear push-through tests using various connector diameters and insertion angles. Larger connectors were stronger but more likely to pull out. Seven flexure tests were conducted on the new wall design reinforced with different combinations of steel and BFRP connectors and reinforcement. Composite action varied from 50 to 90% depending on connector and reinforcement material. Following this study, the axial-bending interaction curves were established for the new wall design using both BFRP and steel connectors and reinforcement. Eight panels were axially loaded to predesignated loads then loaded in flexure to failure. A technique is presented to experimentally determine the effective centroid of partially composite sections. Beyond the tension and compression-controlled failure regions of the interaction curve, a third region was observed in between, governed by connector failure. Theoretical models were developed for the bond

  14. Inhibition of the release of soluble tumor necrosis factor receptors in experimental endotoxemia by an anti-tumor necrosis factor-alpha antibody

    NARCIS (Netherlands)

    Jansen, J.; van der Poll, T.; Levi, M. [=Marcel M.; ten Cate, H.; Gallati, H.; ten Cate, J. W.; van Deventer, S. J.

    1995-01-01

    The role of tumor necrosis factor-alpha in the shedding of soluble tumor necrosis factor receptors in endotoxemia was investigated. The appearance of the soluble tumor necrosis factor receptors was assessed in four healthy volunteers following an intravenous injection of tumor necrosis factor-alpha

  15. Necrosis, a regulated mechanism of cell death La necrosis, un mecanismo regulado de muerte celular

    Directory of Open Access Journals (Sweden)

    Mauricio Rojas López

    2010-05-01

    Full Text Available

    Three types of cellular death have been defined by morphological and biochemical criteria: apoptosis, necrosis and autophagy. Apoptosis is a regulated cell death, mainly mediated by caspases; autophagy induces degradation of intracellular damaged organelles through the formation of vesicles that fuse with hydrolytic vacuoles.

     

    Necrosis has been traditionally defined by the rupture the cytoplasmic membrane with subsequent release of intracellular material, triggering localized inflammatory Intrinsic cellular activities and the events preceding cellular collapse are critical to determine the type of tissue damage.

     

    The fact that all three types of cellular death can coexist in any organ and tissue with different availabilities of ATP, suggests that necrosis can be conceived as an active event and that to some extent it may be regulated. Alterations in the structure of proteins and in the

  16. Predictive value of histologic tumor necrosis after radiation.

    Science.gov (United States)

    Chen, Y; Taghian, A G; Rosenberg, A E; O'Connell, J; Okunieff, P; Suit, H D

    2001-12-20

    Postsurgical evaluation of histologic changes of tumors after preoperative chemotherapy and/or radiotherapy has been a routine clinical practice of pathologists and oncologists. There appears to be secure evidence that the extent of tumor necrosis vs. viable tumor cells postchemotherapy is a clinically useful predictor of outcome. The significance of histologic tumor necrosis after radiotherapy, however, has not been clearly established and deserves further investigation. We investigated the correlation between histological extent of tumor necrosis, survival of tumor transplants, and radiation doses in an experimental model using three human tumor xenografts. Three human tumor cell lines were investigated: STS-26, SCC-21, and HGL-21. Tumors were grown subcutaneously in athymic nude mice and received external beam radiation of different doses. Tumors were excised 2 weeks postirradiation. One-half of the tumor was divided into 1-mm(3) fragments and transplanted to naive mice. The other half was examined for histologic tumor necrosis. Transplant survival was strongly correlated with radiation dose, TCD(p) (radiation dose that results in local tumor control in proportion, p, to irradiated tumors). In contrast, there was no clear association between transplant survival rate and the extent of tumor necrosis. The experimental model demonstrated a strong inverse correlation between radiation doses and tumor transplant survival. Histologic tumor necrosis did not correlate well with radiation doses or transplant survival rates. Despite common practices in histologic examination of tumors posttherapy, clinical interpretations and implications of histologic tumor necrosis after radiotherapy should be considered with caution. Copyright 2001 Wiley-Liss, Inc.

  17. Analysis and enhancement of flexural wave stop bands in 2D periodic plates

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yubao [Laboratory of Science and Technology on Integrated Logistics Support, National University of Defense Technology, 410073 Changsha (China); The Marcus Wallenberg Laboratory for Sound and Vibration Research, KTH – The Royal Institute of Technology, SE-100 44 Stockholm (Sweden); Feng, Leping [The Marcus Wallenberg Laboratory for Sound and Vibration Research, KTH – The Royal Institute of Technology, SE-100 44 Stockholm (Sweden); Wen, Jihong, E-mail: wenjihong_nudt1@vip.sina.com [Laboratory of Science and Technology on Integrated Logistics Support, National University of Defense Technology, 410073 Changsha (China); Yu, Dianlong; Wen, Xisen [Laboratory of Science and Technology on Integrated Logistics Support, National University of Defense Technology, 410073 Changsha (China)

    2015-07-17

    The band structure and enhancement of flexural wave stop bands in a 2D periodic plate are investigated. A unified method for analysing and designing the stop band of the plates with various attached structures is proposed. The effect of attached structures is considered based on their equivalent parameters (added equivalent mass and equivalent moment of inertia). The influences of the equivalent parameters on the band structures are studied. Three cases are considered: adding pure equivalent mass, pure equivalent moment of inertia and the combination of these two. The stop bands are enhanced via the multi interaction between the host plate and the attached structure. The enhancement pattern is determined, and several ways to obtain a wider combined stop band are presented. The frequency response functions of corresponding finite periodic plates are calculated to verify the stop bands and their enhancement in a number of typical cases. - Highlights: • A unified method for studying the stop band of the plates with various simplified attached structures is proposed. • The enhancement of flexural wave stop bands in a 2D phononic plate is investigated. • The stop bands are widened via multi interaction between the host plate and the attached structure. • The enhancement pattern is determined and several ways to get a wider stop band are presented.

  18. Study on Flexural Behaviour of Ternary Blended Reinforced Self Compacting Concrete Beam with Conventional RCC Beam

    Science.gov (United States)

    Marshaline Seles, M.; Suryanarayanan, R.; Vivek, S. S.; Dhinakaran, G.

    2017-07-01

    The conventional concrete when used for structures having dense congested reinforcement, the problems such as external compaction and vibration needs special attention. In such case, the self compacting concrete (SCC) which has the properties like flow ability, passing and filling ability would be an obvious answer. All those SCC flow behavior was governed by EFNARC specifications. In present study, the combination type of SCC was prepared by replacing cement with silica fume (SF) and metakaolin (MK) along with optimum dosages of chemical admixtures. From the fresh property test, cube compressive strength and cylinder split tensile strength, optimum ternary mix was obtained. In order to study the flexural behavior, the optimum ternary mix was taken in which beam specimens of size 1200 mm x 100 mm x 200 mm was designed as singly reinforced section according to IS: 456-2000, Limit state method. Finally the comparative experimental analysis was made between conventional RCC and SCC beams of same grade in terms of flexural strength namely yield load & ultimate load, load- deflection curve, crack size and pattern respectively.

  19. Flexural Behavior of Self-Compacting RC Continuous Beams Strengthened by CFRP Sheets

    Directory of Open Access Journals (Sweden)

    Sabih Z. Al-Sarraf

    2018-01-01

    Full Text Available This search presented an experimental study of the flexural behavior of self-compacting reinforced concrete continuous beams externally strengthened by carbon fiber reinforced polymer (CFRP Sheets. The practical study contained eight self-compacting reinforced concrete continuous beams (with two span, each span had (1500 mm length and (150x250 mm cross sectional dimensions. Seven of these beams strengthened externally by CFRP sheets with and without external anchorage. The experimental variables included location of CFRP sheets and anchor type and location. The results, shows that the beams strengthened externally by CFRP sheets provided improvement in ultimate loads reached (60.71%. The usage of CFRP in the anchorage zone indicated an effective method in comparison to increasing the CFRP sheets lengths or extending them up to the support or under the loading points. Test results also showed that side strengthening provided an effective tool for increasing the load at the cracking stage and also the load capacity and reducing flexural crack widths.

  20. Exact analytical solution of shear-induced flexural vibration of functionally graded piezoelectric beam

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Pankaj, E-mail: psharma@rtu.ac.in; Parashar, Sandeep Kumar, E-mail: parashar2@yahoo.com [Mechanical Engineering Department, Rajasthan Technical University, Kota (India)

    2016-05-06

    The priority of this paper is to obtain the exact analytical solution for free flexural vibration of FGPM beam actuated using the d{sub 15} effect. In piezoelectric actuators, the potential use of d{sub 15} effect has been of particular interest for engineering applications since shear piezoelectric coefficient d15 is much higher than the other piezoelectric coupling constants d{sub 31} and d{sub 33}. The applications of shear actuators are to induce and control the flexural vibrations of beams and plates. In this study, a modified Timoshenko beam theory is used where electric potential is assumed to vary sinusoidaly along the thickness direction. The material properties are assumed to be graded across the thickness in accordance with power law distribution. Hamilton's principle is employed to obtain the equations of motion along with the associated boundary conditions for FGPM beams. Exact analytical solution is derived thus obtained equations of motion. Results for clamped-clamped and clamped-free boundary conditions are presented. The presented result and method shell serve as benchmark for comparing the results obtained from the other approximate methods.

  1. Unified model to predict flexural shear behavior of externally bonded RC beams

    International Nuclear Information System (INIS)

    Colotti, V.; Spadea, G.; Swamy, R.N.

    2006-01-01

    Structural strengthening with externally bonded reinforcement is now recognized as a cost-effective, structurally sound and practically efficient method of rehabilitating deteriorating and damaged reinforced concrete beams. There is now an urgent need to develop a sound engineering basis which can predict the failure loads of all such strengthened beams in a reliable and consistent manner. Existing models to predict the behavior at ultimate of strengthened beams suffer from many limitations and weaknesses. This paper presents a unified global model, based on the Strut-and-Tie approach, to predict the failure loads of reinforced concrete beams strengthened for flexure and/or shear. This structural model is based on rational engineering principles, considers all the possible failure modes, and incorporates the load transfer mechanism bond to reflect the debonding phenomena which has a dominant influence on the failure process of plated beams. The model is validated against about 200 strengthened beam test reported in the literature and failing in flexure and/or shear, involving a large number of structural variables and steel, carbon and glass fiber reinforced polymer laminates as reinforcing medium. (author)

  2. Flexural wave attenuation in a sandwich beam with viscoelastic periodic cores

    Science.gov (United States)

    Guo, Zhiwei; Sheng, Meiping; Pan, Jie

    2017-07-01

    The flexural-wave attenuation performance of traditional constraint-layer damping in a sandwich beam is improved by using periodic constrained-layer damping (PCLD), where the monolithic viscoelastic core is replaced with two periodically alternating viscoelastic cores. Closed-form solutions of the wave propagation constants of the infinite periodic sandwich beam and the forced response of the corresponding finite sandwich structure are theoretically derived, providing computational support on the analysis of attenuation characteristics. In a sandwich beam with PCLD, the flexural waves can be attenuated by both Bragg scattering effect and damping effect, where the attenuation level is mainly dominated by Bragg scattering in the band-gaps and by damping in the pass-bands. Affected by these two effects, when the parameters of periodic cores are properly selected, a sandwich beam with PCLD can effectively reduce vibrations of much lower frequencies than that with traditional constrained-layer damping. The effects of the parameters of viscoelastic periodic cores on band-gap properties are also discussed, showing that the average attenuation in the desired frequency band can be maximized by tuning the length ratio and core thickness to proper values. The research in this paper could possibly provide useful information for the researches and engineers to design damping structures.

  3. Force-Sensing Actuator with a Compliant Flexure-Type Joint for a Robotic Manipulator

    Directory of Open Access Journals (Sweden)

    Mathieu Grossard

    2015-12-01

    Full Text Available This paper deals with the mechatronic design of a novel self-sensing motor-to-joint transmission to be used for the actuation of robotic dexterous manipulators. Backdrivability, mechanical simplicity and efficient flexure joint structures are key concepts that have guided the mechanical design rationale to provide the actuator with force sensing capabilities. Indeed, a self-sensing characteristic is achieved by the specific design of high-resolution cable-driven actuators based on a DC motor, a ball-screw and a monolithic compliant anti-rotation system together with a novel flexure pivot providing a frictionless mechanical structure. That novel compliant pivot with a large angular range and a small center shift has been conceived of to provide the inter-phalangeal rotational degree of freedom of the fingers’ joints to be used for integration in a multi-fingered robotic gripper. Simultaneously, it helps to remove friction at the joint level of the mechanism. Experimental tests carried out on a prototype show an accurate matching between the model and the real behavior. Overall, this mechatronic design contributes to the improvement of the manipulation skills of robotic grippers, thanks to the combination of high performance mechanics, high sensitivity to external forces and compliance control capability.

  4. Clinical importance of median mandibular flexure in oral rehabilitation: a review.

    Science.gov (United States)

    Sivaraman, K; Chopra, A; Venkatesh, S B

    2016-03-01

    The mandible has a property to flex inwards around the mandibular symphysis with change in shape and decrease in mandibular arch width during opening and protrusion of the mandible. The mandibular deformation may range from a few micrometres to more than 1 mm. The movement occurs because of the contraction of lateral pterygoid muscles that pulls mandibular condyles medially and causes a sagittal movement of the posterior segments. This movement of mandible can have a profound influence on prognosis and treatment outcome for various restorative, endodontics, fixed, removable and implant-related prosthesis. The review unfolds the causes, importance and clinical implications of median mandibular flexure in oral rehabilitation. This review also highlights the appropriate preventive measures and techniques that should be adopted by clinicians to minimise the effect of flexural movement of the jaw during oral rehabilitation. This would not only help clinicians to achieve a good prosthesis with accurate fit and longevity but also maintain the health of the surrounding periodontal or periimplant gingival tissues and bone. © 2015 John Wiley & Sons Ltd.

  5. Flexural Strengthening of RC Slabs Using a Hybrid FRP-UHPC System Including Shear Connector

    Directory of Open Access Journals (Sweden)

    Jiho Moon

    2017-01-01

    Full Text Available A polymeric hybrid composite system made of UHPC and CFRP was proposed as a retrofit system to enhance flexural strength and ductility of RC slabs. While the effectiveness of the proposed system was confirmed previously through testing three full-scale one-way slabs having two continuous spans, the slabs retrofitted with the hybrid system failed in shear. This sudden shear failure would stem from the excessive enhancement of the flexural strength over the shear strength. In this study, shear connectors were installed between the hybrid system and a RC slab. Using simple beam, only positive moment section was examined. Two full-scale RC slabs were cast and tested to failure: the first as a control and the second using this new strengthening technique. The proposed strengthening system increased the ultimate load carrying capacity of the slab by 70%, the stiffness by 60%, and toughness by 128%. The efficiency of shear connectors on ductile behavior of the retrofitted slab was also confirmed. After the UHPC top is separated from the slab, the shear connector transfer shear load and the slab system were in force equilibrium by compression in UHPC and tension in CFRP.

  6. Current trends and controversies in the management of patients with splenic flexure tumours

    Directory of Open Access Journals (Sweden)

    Chan DS

    2013-03-01

    Full Text Available Aim: There exists a variation in practice in the management of tumours around the splenic flexure. We aim to determine the current opinion regarding the management of these tumours. Methods: An anonymised 10-part online questionnaire was sent to all members of the Association of Coloproctology of Great Britain and Ireland (ACPGBI. Results: The response rate was 24% (111/464 with approximately half of respondents performing laparoscopic surgery. Electively, an extended right hemicolectomy is the preferred option by 63% of respondents followed by left hemicolectomy (23% and segmental resection (14%. The upper sigmoid and rectosigmoid is the preferred site of anastomosis by 90% and 10% of respondents respectively. There were no significant differences in the type of operations performed by surgeons who practice laparoscopic or open surgery (p=0.10. A hand-sewn end-to-end anastomosis is most commonly performed (51% followed by a stapled side-to-side (36% and a stapled end-to-end (13% technique. Extended right hemicolectomy is also the preferred option in obstructing tumours. Of surgeons who perform segmental resections, 27% perform an on-table lavage and 9% perform a defunctioning stoma. Internal herniation following laparoscopic resection was only reported by a handful of surgeons. Conclusion: Opinion and practice in the management of patients with tumours around the splenic flexure are divided. Further trials are indicated to determine the best practice.

  7. The Effect of Different Shape and Perforated rHDPE in Concrete Structures on Flexural Strength

    Science.gov (United States)

    Yuhazri, MY; Hafiz, KM; Myia, YZA; Jia, CP; Sihombing, H.; Sapuan, SM; Badarulzaman, NA

    2017-10-01

    This research was carried out to develop a reinforcing structure from recycled HDPE plastic lubricant containers to be embedded in concrete structure. Different forms and shapes of recycled HDPE plastic are designed as reinforcement incorporate with cement. In this study, the reinforcing structure was prepared by washing, cutting, dimensioning and joining of the waste HDPE containers (direct technique without treatment on plastic surface). Then, the rHDPE reinforced concrete was produced by casting based on standard of procedure in civil engineering technique. Eight different shapes of rHDPE in concrete structure were used to determine the concrete’s ability in terms of flexural strength. Embedded round shape in solid and perforated of rHDPE in concrete system drastically improved flexural strength at 17.78 % and 13.79 %. The result would seem that the concrete with reinforcing rHDPE structure exhibits a more gradual or flexible properties than concrete beams without reinforcement that has the properties of fragile.

  8. Flexural creep of coated SiC-fiber-reinforced glass-ceramic composites

    International Nuclear Information System (INIS)

    Sun, E.Y.

    1995-01-01

    This study reports the flexural creep behavior of a fiber-reinforced glass-ceramic and associated changes in microstructure. SiC fibers were coated with a dual layer of SiC/BN to provide a weak interface that was stable at high temperatures. Flexural creep, creep-rupture, and creep-strain recovery experiments were conducted on composite material and barium-magnesium aluminosilicate matrix from 1,000 to 1,200 C. Below 1,130 C, creep rates were extremely low (∼10 -9 s -1 ), preventing accurate measurement of the stress dependence. Above 1,130 C, creep rates were in the 10 -8 s -1 range. The creep-rupture strength of the composite at 1,100 C was about 75--80% of the fast fracture strength. Creep-strain recovery experiments showed recovery of up to 90% under prolonged unloading. Experimental creep results from the composite and the matrix were compared, and microstructural observations by TEM were employed to assess the effectiveness of the fiber coatings and to determine the mechanism(s) of creep deformation and damage

  9. A one-piece 3D printed flexure translation stage for open-source microscopy

    Science.gov (United States)

    Sharkey, James P.; Foo, Darryl C. W.; Kabla, Alexandre; Baumberg, Jeremy J.; Bowman, Richard W.

    2016-02-01

    Open source hardware has the potential to revolutionise the way we build scientific instruments; with the advent of readily available 3D printers, mechanical designs can now be shared, improved, and replicated faster and more easily than ever before. However, printed parts are typically plastic and often perform poorly compared to traditionally machined mechanisms. We have overcome many of the limitations of 3D printed mechanisms by exploiting the compliance of the plastic to produce a monolithic 3D printed flexure translation stage, capable of sub-micron-scale motion over a range of 8 × 8 × 4 mm. This requires minimal post-print clean-up and can be automated with readily available stepper motors. The resulting plastic composite structure is very stiff and exhibits remarkably low drift, moving less than 20 μm over the course of a week, without temperature stabilisation. This enables us to construct a miniature microscope with excellent mechanical stability, perfect for time-lapse measurements in situ in an incubator or fume hood. The ease of manufacture lends itself to use in containment facilities where disposability is advantageous and to experiments requiring many microscopes in parallel. High performance mechanisms based on printed flexures need not be limited to microscopy, and we anticipate their use in other devices both within the laboratory and beyond.

  10. Opto-mechanical design of the G-CLEF flexure control camera system

    Science.gov (United States)

    Oh, Jae Sok; Park, Chan; Kim, Jihun; Kim, Kang-Min; Chun, Moo-Young; Yu, Young Sam; Lee, Sungho; Nah, Jakyoung; Park, Sung-Joon; Szentgyorgyi, Andrew; McMuldroch, Stuart; Norton, Timothy; Podgorski, William; Evans, Ian; Mueller, Mark; Uomoto, Alan; Crane, Jeffrey; Hare, Tyson

    2016-08-01

    The GMT-Consortium Large Earth Finder (G-CLEF) is the very first light instrument of the Giant Magellan Telescope (GMT). The G-CLEF is a fiber feed, optical band echelle spectrograph that is capable of extremely precise radial velocity measurement. KASI (Korea Astronomy and Space Science Institute) is responsible for Flexure Control Camera (FCC) included in the G-CLEF Front End Assembly (GCFEA). The FCC is a kind of guide camera, which monitors the field images focused on a fiber mirror to control the flexure and the focus errors within the GCFEA. The FCC consists of five optical components: a collimator including triple lenses for producing a pupil, neutral density filters allowing us to use much brighter star as a target or a guide, a tent prism as a focus analyzer for measuring the focus offset at the fiber mirror, a reimaging camera with three pair of lenses for focusing the beam on a CCD focal plane, and a CCD detector for capturing the image on the fiber mirror. In this article, we present the optical and mechanical FCC designs which have been modified after the PDR in April 2015.

  11. Flexural Capability of Patterned Transparent Conductive Substrate by Performing Electrical Measurements and Stress Simulations

    Directory of Open Access Journals (Sweden)

    Chang-Chun Lee

    2016-10-01

    Full Text Available The suitability of stacked thin films for next-generation display technology was analyzed based on their properties and geometrical designs to evaluate the mechanical reliability of transparent conducting thin films utilized in flexural displays. In general, the high bending stress induced by various operation conditions is a major concern regarding the mechanical reliability of indium–tin–oxide (ITO films deposited on polyethylene terephthalate (PET substrates; mechanical reliability is commonly used to estimate the flexibility of displays. However, the pattern effect is rarely investigated to estimate the mechanical reliability of ITO/PET films. Thus, this study examined the flexible content of patterned ITO/PET films with two different line widths by conducting bending tests and sheet resistance measurements. Moreover, a stress–strain simulation enabled by finite element analysis was performed on the patterned ITO/PET to explore the stress impact of stacked film structures under various levels of flexural load. Results show that the design of the ITO/PET film can be applied in developing mechanically reliable flexible electronics.

  12. Flexural Behavior of RC Members Using Externally Bonded Aluminum-Glass Fiber Composite Beams

    Directory of Open Access Journals (Sweden)

    Ki-Nam Hong

    2014-03-01

    Full Text Available This study concerns improvement of flexural stiffness/strength of concrete members reinforced with externally bonded, aluminum-glass fiber composite (AGC beams. An experimental program, consisting of seven reinforced concrete slabs and seven reinforced concrete beams strengthened in flexure with AGC beams, was initiated under four-point bending in order to evaluate three parameters: the cross-sectional shape of the AGC beam, the glass fiber fabric array, and the installation of fasteners. The load-deflection response, strain distribution along the longitudinal axis of the beam, and associated failure modes of the tested specimens were recorded. It was observed that the AGC beam led to an increase of the initial cracking load, yielding load of the tension steels and peak load. On the other hand, the ductility of some specimens strengthened was reduced by more than 50%. The A-type AGC beam was more efficient in slab specimens than in beam specimens and the B-type was more suitable for beam specimens than for slabs.

  13. Flexural Strengthening of RC Slabs with Prestressed CFRP Strips Using Different Anchorage Systems

    Directory of Open Access Journals (Sweden)

    José Sena-Cruz

    2015-10-01

    Full Text Available Externally Bonded Reinforcement (EBR technique has been widely used for flexural strengthening of concrete structures by using carbon fiber-reinforced polymers (CFRP. EBR technique offers several structural advantages when the CFRP material is prestressed. This paper presents an experimental and numerical study on reinforced (RC slabs strengthened in flexure with prestressed CFRP strips as a structural strengthening system. The strips are applied as an externally bonded reinforcement (EBR and anchored with either a mechanical or a gradient anchorage. The former foresees metallic anchorage plates fixed to the concrete substrate, while the latter is based on an accelerated epoxy resin curing followed by a segment-wise prestress force decrease at the strip ends. Both anchorage systems, in combination with different CFRP strip geometries, were subjected to static loading tests. It could be demonstrated that the composite strip’s performance is better exploited when prestressing is used, with slightly higher overall load carrying capacities for mechanical anchorages than for the gradient anchorage. The performed investigations by means of a cross-section analysis supported the experimental observation that in case a mechanical anchorage is used, progressive strip debonding changes the fully bonded configuration to an unbonded end-anchored system. The inclusion of defined debonding criteria for both the anchorage zones and free length between the anchorage regions allowed to precisely capture the ultimate loading forces.

  14. Compressive and Flexural Tests on Adobe Samples Reinforced with Wire Mesh

    Science.gov (United States)

    Jokhio, G. A.; Al-Tawil, Y. M. Y.; Syed Mohsin, S. M.; Gul, Y.; Ramli, N. I.

    2018-03-01

    Adobe is an economical, naturally available, and environment friendly construction material that offers excellent thermal and sound insulations as well as indoor air quality. It is important to understand and enhance the mechanical properties of this material, where a high degree of variation is reported in the literature owing to lack of research and standardization in this field. The present paper focuses first on the understanding of mechanical behaviour of adobe subjected to compressive stresses as well as flexure and then on enhancing the same with the help of steel wire mesh as reinforcement. A total of 22 samples were tested out of which, 12 cube samples were tested for compressive strength, whereas 10 beams samples were tested for modulus of rupture. Half of the samples in each category were control samples i.e. without wire mesh reinforcement, whereas the remaining half were reinforced with a single layer of wire mesh per sample. It has been found that the compressive strength of adobe increases by about 43% after adding a single layer of wire mesh reinforcement. The flexural response of adobe has also shown improvement with the addition of wire mesh reinforcement.

  15. Juvenile colon cancer at the splenic flexure with a splenic abscess developing 22 years after irradiation for a neuroblastoma

    International Nuclear Information System (INIS)

    Tamura, Toshihisa; Higure, Aiichiro; Akiyama, Masaki; Nagata, Naoki; Hirata, Keiji; Yamaguchi, Koji

    2010-01-01

    A 23-year-old woman who had an operation and chemo-radiation therapy for a neuroblastoma of the left adrenal gland at the age of five months developed a fever and left hypochondralgia when she was 22 years old. A splenic abscess was noted. Percutaneous drainage was done, but the splenic abscess recurred. There was no recurrence of the neuroblastoma. Conservative therapy was unsuccessful and a laparotomy was performed. Operative findings included a bulky mass at the splenic flexure which involved the spleen, pancreas tail, and jejunum. Colectomy at the splenic flexure was performed with coresection of the spleen, pancreas tail, and jejunum. The surgical specimen showed mucinous carcinoma of the splenic flexure which invaded the spleen. This case was considered to be an radiation-induced secondary colon cancer. (author)

  16. A study on flexural and water absorption of surface modified rice husk flour/E-glass/polypropylene hybrid composite

    Science.gov (United States)

    Rassiah, K.; Sin, T. W.; Ismail, M. Z.

    2016-10-01

    This work is to study the effects of rice husk (RH)/E-Glass (EG)/polypropylene (PP) hybrid composites in terms of flexural and water absorption properties. The tests conducted are the flexural test and also the water absorption test using two types of water: distilled and sea water. The hybrid composites are prepared with various ratios of fibre weight fractions and the rice husk is treated using 2% Sodium Hydroxide (NaOH) to improve interaction and adhesion between the non-polar matrix and the polar lignocellulosic fibres. It was found that the content of rice husk/E-Glass fillers affected the structural integrity and flexural properties of hybrid composites. In addition, a higher ratio of rice husk contributes to higher water absorption in the hybrid composites.

  17. United Kingdom nationwide study of avascular necrosis of the jaws including bisphosphonate-related necrosis.

    Science.gov (United States)

    Rogers, S N; Palmer, N O A; Lowe, D; Randall, C

    2015-02-01

    We aimed to record all new patients who presented to departments of oral surgery, oral medicine, and oral and maxillofacial surgery, and to dental hospitals in the UK, with avascular necrosis of the jaws including bisphosphonate-related necrosis (BRONJ) over a 2-year period (1 June 2009-31 May 2011). They were eligible irrespective of age, cause, or coexisting conditions. Data on incidence, clinical characteristics, risk factors, and coexisting conditions were collected. A total of 383 cases were registered: 369 were described as BRONJ, 5 as avascular necrosis, and 9 were unknown. Bisphosphonates had been given orally in 207 (56%), intravenously in 125 (34%), both orally and intravenously in 27 (7%), and was unknown in 9 (2%); one had been given denosumab. The main risk factor was dental extraction, and the mandible was commonly affected. The median duration of administration until onset of BRONJ was 3 years in those treated intravenously and 4 years in those treated orally. Levels of engagement with the study varied between regions, and extrapolation from the 2 most involved (Merseyside and Northern Ireland) found around 8.2-12.8 cases/million/year, which is 508-793 patients/year across the UK. To our knowledge this is one of the first studies to estimate national rates of BRONJ. It confirms that the risk and incidence are low. With changes in trends for antiresorptive bone medication, and increasing numbers of elderly people, it would be useful to repeat the registration in the future. Copyright © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  18. Flexural strength and microstructure of two lithium disilicate glass ceramics for CAD/CAM restoration in the dental clinic

    Directory of Open Access Journals (Sweden)

    Suk-Ho Kang

    2013-08-01

    Full Text Available Objectives There has been a growing interest in glass ceramic systems with good esthetics, high fracture resistance and bonding durability, and simplified fabrication techniques using CAD/CAM. The aim of this study is to compare flexural strength before and after heat treatment of two lithium disilicate CAD/CAM blocks, IPS e.max CAD (Ivoclar Vivadent and Rosetta SM (Hass, and to observe their crystalline structures. Materials and Methods Biaxial flexural strength was tested according to ISO 6872 with 20 disc form specimens sliced from each block before and after heat treatment. Also, the crystalline structures were observed using field-emission scanning microscopy (FE-SEM, Hitachi and x-ray diffraction (XRD, Rigaku analysis. The mean values of the biaxial flexural strength were analyzed by the Mann-Whitney U test at a significance level of p = 0.05. Results There were no statistically significant differences in flexural strength between IPS e.max CAD and Rosetta SM either before heat treatment or after heat treatment. For both ceramics, the initial flexural strength greatly increased after heat treatment, with significant differences (p < 0.05. The FE-SEM images presented similar patterns of crystalline structure in the two ceramics. In the XRD analysis, they also had similar patterns, presenting high peak positions corresponding to the standard lithium metasilicate and lithium disilicate at each stage of heat treatment. Conclusions IPS e.max CAD and Rosetta SM showed no significant differences in flexural strength. They had a similar crystalline pattern and molecular composition.

  19. Challenges With the Diagnosis and Treatment of Cerebral Radiation Necrosis

    International Nuclear Information System (INIS)

    Chao, Samuel T.; Ahluwalia, Manmeet S.; Barnett, Gene H.; Stevens, Glen H.J.; Murphy, Erin S.; Stockham, Abigail L.; Shiue, Kevin; Suh, John H.

    2013-01-01

    The incidence of radiation necrosis has increased secondary to greater use of combined modality therapy for brain tumors and stereotactic radiosurgery. Given that its characteristics on standard imaging are no different that tumor recurrence, it is difficult to diagnose without use of more sophisticated imaging and nuclear medicine scans, although the accuracy of such scans is controversial. Historically, treatment had been limited to steroids, hyperbaric oxygen, anticoagulants, and surgical resection. A recent prospective randomized study has confirmed the efficacy of bevacizumab in treating radiation necrosis. Novel therapies include using focused interstitial laser thermal therapy. This article will review the diagnosis and treatment of radiation necrosis

  20. Avascular necrosis of the femoral head presenting as trochanteric bursitis.

    Science.gov (United States)

    Mandell, B F

    1990-01-01

    Five patients are described with avascular necrosis of the femoral head who presented with ipsilateral trochanteric bursitis, in the absence of clearcut hip joint disease. Avascular necrosis was indicated by magnetic resonance imaging. It is suggested that clinical trochanteric bursitis, especially when refractory to local corticosteroid treatment, may be the initial sign of hip disease. In the patient with risk factor(s) for avascular necrosis that diagnosis should be considered and evaluated with appropriate studies, such as magnetic resonance imaging, to prevent weight bearing at an early stage and permit possible surgical decompression in the hope of postponing or obviating the need for total hip replacement. PMID:2241294

  1. MR imaging of avascular necrosis of carpal bones

    International Nuclear Information System (INIS)

    Taniguchi, Yasunori; Funaoka, Nobuhiko; Yoshida, Munehito; Iwahashi, Toshiyuki; Egawa, Hiromitsu; Shima, Kimihiro; Tamaoki, Tetsuya.

    1991-01-01

    The usefulness of MRI in carpal avascular necrosis was investigated in 20 cases, 16 in lunates, 3 in scaphoids and 1 in triquetrum, with T1 and T2 weighted images of the spin echo and T2 weighted images of the field echo. Early diagnosis of carpal bone necrosis was possible when the T1 weighted image showed a moderate low intensity signal. A high intensity signal in the T2 weighted image indicated the onset of revascularization, and a favorable prognosis. A normal signal indicated healing of carpal avascular necrosis. MRI was found to be very useful in establishing the diagnosis and in determining the prognosis of carpal osteonecrosis. (author)

  2. MR imaging of avascular necrosis of carpal bones

    Energy Technology Data Exchange (ETDEWEB)

    Taniguchi, Yasunori; Funaoka, Nobuhiko; Yoshida, Munehito [Kinan General Hospital, Wakayama (Japan); Iwahashi, Toshiyuki; Egawa, Hiromitsu; Shima, Kimihiro; Tamaoki, Tetsuya

    1991-03-01

    The usefulness of MRI in carpal avascular necrosis was investigated in 20 cases, 16 in lunates, 3 in scaphoids and 1 in triquetrum, with T1 and T2 weighted images of the spin echo and T2 weighted images of the field echo. Early diagnosis of carpal bone necrosis was possible when the T1 weighted image showed a moderate low intensity signal. A high intensity signal in the T2 weighted image indicated the onset of revascularization, and a favorable prognosis. A normal signal indicated healing of carpal avascular necrosis. MRI was found to be very useful in establishing the diagnosis and in determining the prognosis of carpal osteonecrosis. (author).

  3. Avascular necrosis of the trapezoid bone following carpometacarpal arthroplasty.

    Science.gov (United States)

    Kane, Patrick; Waryasz, Greg; Katarincic, Julie

    2014-03-03

    A 58-year-old female developed avascular necrosis of her trapezoid approximately 3 months after undergoing carpometacarpal arthroplasty. The patient was treated conservatively with immobilization and had complete resolution of her clinical symptoms during her year of follow-up. Additionally, radiographic examination showed complete restoration of the height of her trapezoid approximately 1 year after the index procedure. Avascular necrosis of the trapezoid is extremely rare with very few cases described in the literature. This is the first description of avascular necrosis following carpometacarpal arthroplasty.

  4. Excessive heat-associated gingival necrosis: a case report.

    Science.gov (United States)

    Barnes, P L; Rossi-Fedele, G

    2017-09-01

    Heat-delivery devices have been associated with relatively high temperatures. Previous basic research studies suggest that the risk for periodontal tissues is negligible, as the presence of the root filling materials, amongst other factors, reduce the risk of overheating. This report describes the case of a 45 year old male, who was undergoing restorative treatment in a multi-specialty dental practice. As part of his overall treatment planning, orthograde root canal retreatment for his maxillary left incisor teeth was deemed necessary, due to chronic apical periodontitis. Following cold lateral compaction, the coronal portion of the core material was severed using a System B Heat Source (Kerr Dental, Orange, CA, USA), with the patient reporting pain as well as a burning sensation. The following day the patient was seen by a periodontist and gingival necrosis in relation to the central incisor was found. The most likely cause of the complication was considered to be excessive heat during the operative procedure. The patient was followed up for a 2-year period and the soft tissues returned to their original condition without the need for periodontal treatment. © 2017 Australian Dental Association.

  5. Plaquing procedure for infectious hematopoietic necrosis virus

    Science.gov (United States)

    Burke, J.A.; Mulcahy, D.

    1980-01-01

    A single overlay plaque assay was designed and evaluated for infectious hematopoietic necrosis virus. Epithelioma papillosum carpio cells were grown in normal atmosphere with tris(hydroxymethyl)aminomethane- or HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid)-buffered media. Plaques were larger and formed more quickly on 1- to 3-day-old cell monolayers than on older monolayers. Cell culture medium with a 10% addition of fetal calf serum (MEM 10) or without serum (MEM 0) were the most efficient virus diluents. Dilution with phosphate-buffered saline, saline, normal broth, or deionized water reduced plaque numbers. Variations in the pH (7.0 to 8.0) of a MEM 0 diluent did not affect plaque numbers. Increasing the volume of viral inoculum above 0.15 ml (15- by 60-mm plate) decreased plaquing efficiency. Significantly more plaques occurred under gum tragacanth and methylcellulose than under agar or agarose overlays. Varying the pH (6.8 to 7.4) of methylcellulose overlays did not significantly change plaque numbers. More plaques formed under the thicker overlays of both methylcellulose and gum tragacanth. Tris(hydroxymethyl)aminomethane and HEPES performed equally well, buffering either medium or overlay. Plaque numbers were reduced when cells were rinsed after virus adsorption or less than 1 h was allowed for adsorption. Variation in adsorption time between 60 and 180 min did not change plaque numbers. The mean plaque formation time was 7 days at 16 degrees C. The viral dose response was linear when the standardized assay was used.

  6. Management Options in Avascular Necrosis of Talus.

    Science.gov (United States)

    Dhillon, Mandeep S; Rana, Balvinder; Panda, Inayat; Patel, Sandeep; Kumar, Prasoon

    2018-01-01

    Avascular necrosis (AVN) of the talus can be a cause of significant disability and is a difficult problem to treat. The most common cause is a fracture of the talus. We have done a systematic review of the literature with the following aims: (1) identify and summarize the available evidence in literature for the treatment of talar AVN, (2) define the usefulness of radiological Hawkins sign and magnetic resonance imaging in early diagnosis, and (3) provide patient management guidelines. We searched MEDLINE and PUBMED using keywords and MESH terminology. The articles' abstracts were read by two of the authors. Forty-one studies met the inclusion criteria of the 335 abstracts screened. The interventions of interest included hindfoot fusion, conservative measures, bone grafting, vascularized bone graft, core decompression, and talar replacement. All studies were of Level IV evidence. We looked to identify the study quality, imprecise and sparse data, reporting bias, and the quality of evidence. Based on the analysis of available literature, we make certain recommendations for managing patients of AVN talus depending on identified disease factors such as early or late presentation, extent of bone involvement, bone collapse, and presence or absence of arthritis. Early talar AVN seems best treated with protected weight bearing and possibly in combination with extracorporeal shock wave therapy. If that fails, core decompression can be considered. Arthrodesis should be saved as a salvage procedure in late cases with arthritis and collapse, and a tibiotalocalcaneal fusion with bone grafting may be needed in cases of significant bone loss. Role of vascularized bone grafting is still not defined clearly and needs further investigation. Future prospective, randomized studies are necessary to guide the conservative and surgical management of talar AVN.

  7. Management options in avascular necrosis of talus

    Directory of Open Access Journals (Sweden)

    Mandeep S Dhillon

    2018-01-01

    Full Text Available Avascular necrosis (AVN of the talus can be a cause of significant disability and is a difficult problem to treat. The most common cause is a fracture of the talus. We have done a systematic review of the literature with the following aims: (1 identify and summarize the available evidence in literature for the treatment of talar AVN, (2 define the usefulness of radiological Hawkins sign and magnetic resonance imaging in early diagnosis, and (3 provide patient management guidelines. We searched MEDLINE and PUBMED using keywords and MESH terminology. The articles' abstracts were read by two of the authors. Forty-one studies met the inclusion criteria of the 335 abstracts screened. The interventions of interest included hindfoot fusion, conservative measures, bone grafting, vascularized bone graft, core decompression, and talar replacement. All studies were of Level IV evidence. We looked to identify the study quality, imprecise and sparse data, reporting bias, and the quality of evidence. Based on the analysis of available literature, we make certain recommendations for managing patients of AVN talus depending on identified disease factors such as early or late presentation, extent of bone involvement, bone collapse, and presence or absence of arthritis. Early talar AVN seems best treated with protected weight bearing and possibly in combination with extracorporeal shock wave therapy. If that fails, core decompression can be considered. Arthrodesis should be saved as a salvage procedure in late cases with arthritis and collapse, and a tibiotalocalcaneal fusion with bone grafting may be needed in cases of significant bone loss. Role of vascularized bone grafting is still not defined clearly and needs further investigation. Future prospective, randomized studies are necessary to guide the conservative and surgical management of talar AVN.

  8. Management Options in Avascular Necrosis of Talus

    Science.gov (United States)

    Dhillon, Mandeep S; Rana, Balvinder; Panda, Inayat; Patel, Sandeep; Kumar, Prasoon

    2018-01-01

    Avascular necrosis (AVN) of the talus can be a cause of significant disability and is a difficult problem to treat. The most common cause is a fracture of the talus. We have done a systematic review of the literature with the following aims: (1) identify and summarize the available evidence in literature for the treatment of talar AVN, (2) define the usefulness of radiological Hawkins sign and magnetic resonance imaging in early diagnosis, and (3) provide patient management guidelines. We searched MEDLINE and PUBMED using keywords and MESH terminology. The articles' abstracts were read by two of the authors. Forty-one studies met the inclusion criteria of the 335 abstracts screened. The interventions of interest included hindfoot fusion, conservative measures, bone grafting, vascularized bone graft, core decompression, and talar replacement. All studies were of Level IV evidence. We looked to identify the study quality, imprecise and sparse data, reporting bias, and the quality of evidence. Based on the analysis of available literature, we make certain recommendations for managing patients of AVN talus depending on identified disease factors such as early or late presentation, extent of bone involvement, bone collapse, and presence or absence of arthritis. Early talar AVN seems best treated with protected weight bearing and possibly in combination with extracorporeal shock wave therapy. If that fails, core decompression can be considered. Arthrodesis should be saved as a salvage procedure in late cases with arthritis and collapse, and a tibiotalocalcaneal fusion with bone grafting may be needed in cases of significant bone loss. Role of vascularized bone grafting is still not defined clearly and needs further investigation. Future prospective, randomized studies are necessary to guide the conservative and surgical management of talar AVN. PMID:29887631

  9. Kyrieleis plaques associated with Herpes Simplex Virus type 1 acute retinal necrosis

    Directory of Open Access Journals (Sweden)

    Neha Goel

    2016-04-01

    Full Text Available We report the case of a 55-year-old immunocompetent male who presented with features typical of acute retinal necrosis (ARN. Polymerase chain reaction of the aqueous tap was positive for Herpes Simplex Virus (HSV – 1. Following therapy with intravenous Acyclovir, followed by oral Acyclovir and steroids, there was marked improvement in the visual acuity and clinical picture. At one week after initiation of treatment, Kyrieleis plaques were observed in the retinal arteries. They became more prominent despite resolution of the vitritis, retinal necrosis and vasculitis and persisted till six weeks of follow-up, when fluorescein angiography was performed. The appearance of this segmental retinal periarteritis also known as Kyrieleis plaques has not been described in ARN due to HSV-1 earlier.

  10. Direct therapeutic applications of calcium electroporation to effectively induce tumor necrosis

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gissel, Hanne; Hojman, Pernille

    2012-01-01

    in vivo. Calcium electroporation elicited dramatic antitumor responses in which 89% of treated tumors were eliminated. Histologic analyses indicated complete tumor necrosis. Mechanistically, calcium electroporation caused acute ATP depletion likely due to a combination of increased cellular use of ATP......, decreased production of ATP due to effects on the mitochondria, as well as loss of ATP through the permeabilized cell membrane. Taken together, our findings offer a preclinical proof of concept for the use of electroporation to load cancer cells with calcium as an efficient anticancer treatment...

  11. Avascular necrosis in sickle cell (homozygous S) patients: Predictive ...

    African Journals Online (AJOL)

    2013-04-24

    Apr 24, 2013 ... Results: The prevalence of AVN in sickle cell patients was ... Key words: Avascular necrosis, homozygous S, platelet count, sickle cell anemia, white cell count .... frequency of vaso‑occlusive crisis, platelet, and white cell.

  12. 'Femoral head necrosis' in metabolic and hormonal osteopathies

    International Nuclear Information System (INIS)

    Heuck, F.H.W.; Treugut, H.

    1984-01-01

    The pathogenesis of bone necrosis is discussed with special attention and with respect to metabolic, hormonal, and vascular factors. The influence of statics and dynamics of the hip joint bones for the development of aseptic necrosis are discussed. 45 patients with ''idiopathic femoral head necroses'' were observed, including 6 cases of renal osteopathy following renal transplantation and immune suppression therapy, 14 cases of long term corticoid therapy, and 11 cases of liver diseases of different genesis. The femoral head necrosis understood as complication of an osteopathy. In our patients there were 31 males and 14 females - which means higher involvement of males. Plain radiological findings and CT-findings of changes of the femoral heat structure in different stages of the disease are described. Early diagnosis of metabolic and hormonal osteopathies is demanded for a joint keeping therapy of the beginning femoral head necrosis. (orig.) [de

  13. Prevalence and associations of symptomatic renal papillary necrosis ...

    African Journals Online (AJOL)

    2015-11-12

    Nov 12, 2015 ... Diagnosis was based on microscopic hematuria and positive ultrasound findings. Their steady ... until recently the most widely accepted first account was documented by ... papillary necrosis in sickle cell anemia patients in.

  14. Mammographic and sonographic features of fat necrosis of the breast

    International Nuclear Information System (INIS)

    Upadhyaya, Vidya S; Uppoor, Raghuraj; Shetty, Lathika

    2013-01-01

    Imaging features of fat necrosis vary depending on its stage of evolution and can mimic malignancy in late stages. Imaging may suffice to differentiate fat necrosis in the early stages from malignancy and thus avoid unnecessary biopsy. In this pictorial essay, we present combination of benign features in mammography and/or ultrasonography (USG) that can lead to imaging diagnosis of fat necrosis. The follow-up imaging features of fat necrosis which mirror its pathophysiological evolution have also been demonstrated. To summarize, in the appropriate clinical setting, no mammographic features suspicious for malignancy should be present. When the typical mammographic features are not present, USG can aid with the diagnosis and follow up USG can confirm it

  15. A Case of Trapezium Avascular Necrosis Treated Conservatively.

    Science.gov (United States)

    Petsatodis, Evangelos; Ditsios, Konstantinos; Konstantinou, Panagiotis; Pinto, Iosafat; Kostretzis, Lazaros; Theodoroudis, Ioannis; Pilavaki, Mayia

    2017-01-01

    Avascular necrosis (AVN) of the bones of the wrist most commonly involves the lunate followed by the proximal pole of the scaphoid and the capitate. Trapezium avascular necrosis is extremely rare with only two cases reported in the literature, both of which were treated surgically. In this article, we report a unique case of trapezium avascular necrosis treated conservatively. A 38-year-old man complaining of a 4-month history of mild pain on the base of his right thumb. MRI scan was performed. The clinical presentation and the imaging findings indicated avascular osteonecrosis of the trapezium. The patient was treated with immobilization of the wrist joint for a period of six weeks. Three months later, the patient was free of symptoms and the MRI scan revealed a normal trapezium. AVN of trapezium is extremely rare. Our case shows that immobilization of an early stage avascular necrosis of the trapezium might be a treatment option.

  16. A Case of Trapezium Avascular Necrosis Treated Conservatively

    Directory of Open Access Journals (Sweden)

    Evangelos Petsatodis

    2017-01-01

    Full Text Available Introduction. Avascular necrosis (AVN of the bones of the wrist most commonly involves the lunate followed by the proximal pole of the scaphoid and the capitate. Trapezium avascular necrosis is extremely rare with only two cases reported in the literature, both of which were treated surgically. In this article, we report a unique case of trapezium avascular necrosis treated conservatively. Case Presentation. A 38-year-old man complaining of a 4-month history of mild pain on the base of his right thumb. MRI scan was performed. The clinical presentation and the imaging findings indicated avascular osteonecrosis of the trapezium. The patient was treated with immobilization of the wrist joint for a period of six weeks. Three months later, the patient was free of symptoms and the MRI scan revealed a normal trapezium. Conclusion. AVN of trapezium is extremely rare. Our case shows that immobilization of an early stage avascular necrosis of the trapezium might be a treatment option.

  17. Bilateral streptococcal corneoscleritis complicating β irradiation induced scleral necrosis

    International Nuclear Information System (INIS)

    Moriarty, A.P.; Crawford, G.J.; McAllister, I.L.; Constable, I.J.

    1993-01-01

    Bacterial corneoscleritis may complicate scleral necrosis induced by β irradiation following pterygium removal. Previous cases have been unilateral. The authors report a case of severe bilateral corneoscleritis caused by Streptococcus pneumoniae. (author)

  18. FLEXURAL TESTING OF WOOD-CONCRETE COMPOSITE BEAM MADE FROM KAMPER AND BANGKIRAI WOOD

    Directory of Open Access Journals (Sweden)

    Fengky Satria Yoresta

    2015-07-01

    Full Text Available Certain wood has a tensile strength that almost equal with steel rebar in reinforced concrete beams. This research aims to understand the capacity and flexural behavior of concrete beams reinforced by wood (wood-concrete composite beam. Two different types of beams based on placement positions of wood layers are proposed in this study. Two kinds of wood used are consisted of Bangkirai (Shorea laevifolia and Kamper (Cinnamomum camphora, meanwhile the concrete mix ratio for all beams is 1 cement : 2 fine aggregates : 3 coarse aggregates. Bending test is conducted by using one-point loading method. The results show that composite beam using Bangkirai wood is stronger than beams using Kamper wood. More thicker wood layer in tensile area will increase the flexural strength of beams. Crack patterns identified could be classified into flexural cracks, shear cracks, and split on wood layer   Beberapa jenis kayu tertentu memiliki kekuatan tarik yang hampir sama dengan tulangan baja pada balok beton bertulang. Penelitian ini bertujuan memahami kapasitas dan perilaku lentur balok beton bertulang yang diperkuat menggunakan kayu (balok komposit beton-kayu. Dua tipe balok yang berbeda berdasarkan posisi penempatan kayu digunakan dalam penelitian ini. Dua jenis kayu yang digunakan adalah kayu Bangkirai (Shorea laevifolia and Kamper (Cinnamomum camphora, sementara itu rasio campuran beton untuk semua balok menggunakan perbandingan 1 semen : 2 agregat halus : 3 agregat kasar. Pengujian lentur dilakukan menggunakan metode one-point loading. Hasil penelitian menunjukkan bahwa balok komposit dengan kayu Bangkirai lebih kuat dibandingkan balok dengan kayu Kamper. Semakin tebal lapisan kayu yang berada di daerah tarik akan meningkatkan kekuatan lentur balok. Pola kerusakan yang teridentifikasi dapat diklasifikasikan menjadi retak lentur, retak geser, dan pecah pada kayu REFERENCES Boen T. (2010. Retrofitting Simple Buildings Damaged by Earthquakes. World Seismic

  19. Magma explains low estimates of lithospheric strength based on flexure of ocean island loads

    Science.gov (United States)

    Buck, W. Roger; Lavier, Luc L.; Choi, Eunseo

    2015-04-01

    One of the best ways to constrain the strength of the Earth's lithosphere is to measure the deformation caused by large, well-defined loads. The largest, simple vertical load is that of the Hawaiian volcanic island chain. An impressively detailed recent analysis of the 3D response to that load by Zhong and Watts (2013) considers the depth range of seismicity below Hawaii and the seismically determined geometry of lithospheric deflection. These authors find that the friction coefficient for the lithosphere must be in the normal range measured for rocks, but conclude that the ductile flow strength has to be far weaker than laboratory measurements suggest. Specifically, Zhong and Watts (2013) find that stress differences in the mantle lithosphere below the island chain are less than about 200 MPa. Standard rheologic models suggest that for the ~50 km thick lithosphere inferred to exist below Hawaii yielding will occur at stress differences of about 1 GPa. Here we suggest that magmatic accommodation of flexural extension may explain Hawaiian lithospheric deflection even with standard mantle flow laws. Flexural stresses are extensional in the deeper part of the lithosphere below a linear island load (i.e. horizontal stresses orthogonal to the line load are lower than vertical stresses). Magma can accommodate lithospheric extension at smaller stress differences than brittle and ductile rock yielding. Dikes opening parallel to an island chain would allow easier downflexing than a continuous plate, but wound not produce a freely broken plate. The extensional stress needed to open dikes at depth depends on the density contrast between magma and lithosphere, assuming magma has an open pathway to the surface. For a uniform lithospheric density ρL and magma density ρM the stress difference to allow dikes to accommodate extension is: Δσxx (z) = g z (ρM - gρL), where g is the acceleration of gravity and z is depth below the surface. For reasonable density values (i.e.

  20. Genetic ablation of soluble tumor necrosis factor with preservation of membrane tumor necrosis factor is associated with neuroprotection after focal cerebral ischemia

    DEFF Research Database (Denmark)

    Madsen, Pernille M; Clausen, Bettina H; Degn, Matilda

    2016-01-01

    Microglia respond to focal cerebral ischemia by increasing their production of the neuromodulatory cytokine tumor necrosis factor, which exists both as membrane-anchored tumor necrosis factor and as cleaved soluble tumor necrosis factor forms. We previously demonstrated that tumor necrosis factor...... reduced infarct volumes at one and five days after stroke. This was associated with improved functional outcome after experimental stroke. No changes were found in the mRNA levels of tumor necrosis factor and tumor necrosis factor-related genes (TNFR1, TNFR2, TACE), pro-inflammatory cytokines (IL-1β, IL-6...... knockout mice display increased lesion volume after focal cerebral ischemia, suggesting that tumor necrosis factor is neuroprotective in experimental stroke. Here, we extend our studies to show that mice with intact membrane-anchored tumor necrosis factor, but no soluble tumor necrosis factor, display...

  1. Evaluation of biaxial flexural strength and modulus of filled and unfilled adhesive systems = Avaliação da resistência flexural biaxial e módulo de flexão de sistemas adesivos

    Directory of Open Access Journals (Sweden)

    Liberti, Michele Santana

    2009-01-01

    Full Text Available Objetivo: O objetivo deste estudo foi avaliar a resistência flexural e o módulo de flexão de dois sistemas adesivos, através de ensaio de resistência flexural biaxial. Metodologia: Os adesivos (Pentron Clinical Technologies estudados foram: Bond 1 (B1 e NanoBond (NB. Treze discos de cada adesivo foram preparados com dimensões aproximadas de 6,1 mm de diâmetro e 0,6 mm de espessura. Os discos de adesivos foram confeccionados utilizando-se moldes de teflon e fotopolimerizados com aparelho XL 3000 (3M ESPE. Após armazenamento por 10 dias, os discos foram testados em máquina universal de ensaio (Instron 5844, com velocidade de 1,27 mm/min. Os dados foram submetidos à análise de variância (1 fator ao nível de significância de 0,05. Resultados: Os valores médios (±DP de resistência flexural para os adesivos foram (em MPa: B1- 89,7±7,6 e NB- 131,1±9,5. Os valores médios de módulo flexural (±DP foram (em MPa: B1- 1999,9±258,4 e NB- 2314,5±271,0. Conclusão: O adesivo contendo partículas de carga (NB mostrou maiores valores de resistência flexural e módulo de flexão que o adesivo B1

  2. Modeling and experimental study on near-field acoustic levitation by flexural mode.

    Science.gov (United States)

    Liu, Pinkuan; Li, Jin; Ding, Han; Cao, Wenwu

    2009-12-01

    Near-field acoustic levitation (NFAL) has been used in noncontact handling and transportation of small objects to avoid contamination. We have performed a theoretical analysis based on nonuniform vibrating surface to quantify the levitation force produced by the air film and also conducted experimental tests to verify our model. Modal analysis was performed using ANSYS on the flexural plate radiator to obtain its natural frequency of desired mode, which is used to design the measurement system. Then, the levitation force was calculated as a function of levitation distance based on squeeze gas film theory using measured amplitude and phase distributions on the vibrator surface. Compared with previous fluid-structural analyses using a uniform piston motion, our model based on the nonuniform radiating surface of the vibrator is more realistic and fits better with experimentally measured levitation force.

  3. Influence of Tension Stiffening on the Flexural Stiffness of Reinforced Concrete Circular Sections.

    Science.gov (United States)

    Morelli, Francesco; Amico, Cosimo; Salvatore, Walter; Squeglia, Nunziante; Stacul, Stefano

    2017-06-18

    Within this paper, the assessment of tension stiffening effects on a reinforced concrete element with the circular sections subjected to axial and bending loads is presented. To this purpose, an enhancement of an analytical model already present within the actual technical literature is proposed. The accuracy of the enhanced method is assessed by comparing the experimental results carried out in past research and the numerical ones obtained by the model. Finally, a parametric study is executed in order to study the influence of axial compressive force on the flexural stiffness of reinforced concrete elements that are characterized by a circular section, comparing the secant stiffness evaluated at yielding and at maximum resistance, considering and not considering the effects of tension stiffness.

  4. Influence of Tension Stiffening on the Flexural Stiffness of Reinforced Concrete Circular Sections

    Directory of Open Access Journals (Sweden)

    Francesco Morelli

    2017-06-01

    Full Text Available Within this paper, the assessment of tension stiffening effects on a reinforced concrete element with the circular sections subjected to axial and bending loads is presented. To this purpose, an enhancement of an analytical model already present within the actual technical literature is proposed. The accuracy of the enhanced method is assessed by comparing the experimental results carried out in past research and the numerical ones obtained by the model. Finally, a parametric study is executed in order to study the influence of axial compressive force on the flexural stiffness of reinforced concrete elements that are characterized by a circular section, comparing the secant stiffness evaluated at yielding and at maximum resistance, considering and not considering the effects of tension stiffness.

  5. Flexural Behaviour Of Reinforced Concrete Beams Containing Expanded Glass As Lightweight Aggregates

    Directory of Open Access Journals (Sweden)

    Khatib Jamal

    2015-12-01

    Full Text Available The flexural properties of reinforced concrete beams containing expanded glass as a partial fine aggregate (sand replacement are investigated. Four concrete mixes were employed to conduct this study. The fine aggregate was replaced with 0%, 25%, 50% and 100% (by volume expanded glass. The results suggest that the incorporation of 50% expanded glass increased the workability of the concrete. The compressive strength was decreasing linearly with the increasing amount of expanded glass. The ductility of the concrete beam significantly improved with the incorporation of the expanded glass. However, the load-carrying capacity of the beam and load at which the first crack occurs was reduced. It was concluded that the inclusion of expanded glass in structural concrete applications is feasible.

  6. Piezoelectric transduction of flexural modes in pre-stressed microbeam resonators

    International Nuclear Information System (INIS)

    Torri, G B; Rottenberg, X; Hoof, C Van; Puers, R; Tilmans, H A C; Janssen, N M A; Zeng, Z; Karabacak, D M; Vandecasteele, M

    2014-01-01

    This paper reports on the optimization of the design of piezoelectric transducer elements integrated on doubly-clamped microbeam resonators utilized as (bio)chemical sensors. We report and emphasize the often forgotten influence of membrane stresses on defining the dimensions and optimal position of the piezoelectric transducer elements. The study takes into account stress induced structural changes and provides models for the equivalent motional parameters of resonators with particular shapes of the transducers matching the flexural modes of vibration. The above is analyzed theoretically using numerical models and is confirmed by impedance measurements and optical measurements of fabricated doubly-clamped beam resonators. We propose various transducer designs and highlight the advantages of using higher order vibration modes by implementing specially designed mode matching transducer elements. It is concluded that the paper describes and highlights the importance of accounting for the membrane stresses to optimize the resonator performance and the low power in electronic feedback of resonating sensing systems. (paper)

  7. Flexural properties of four fast-growing eucalypts woods deteriorated by three different field tests

    Directory of Open Access Journals (Sweden)

    Rafael de Avila Delucis

    2017-02-01

    Full Text Available Durability is a wood characteristic determined by several factors, making it difficult to investigate the service life of pieces designated for outdoor use. In this study, the decaying of juvenile and adult woods of four fast-growing eucalypts from southern Brazil subjected to three different exposure environments was monitored through mechanical properties (flexural test. The study material was obtained from adult trees of Eucalyptus botryoides, Corymbia citriodora, Eucalyptus paniculata and Eucalyptus tereticornis. Field tests were conducted in the city of Piratini, southern Brazil, and samplings were carried out during 540 days of experiment. Comparing the four eucalypts, the decreasing order of biological resistance was: Eucalyptus tereticornis, Corymbia citriodora, Eucalyptus paniculata and Eucalyptus botryoides. The mature wood showed greater and more stable physical-mechanical properties than juvenile wood.

  8. Exploring biomass based carbon black as filler in epoxy composites: Flexural and thermal properties

    International Nuclear Information System (INIS)

    Abdul Khalil, H.P.S.; Firoozian, P.; Bakare, I.O.; Akil, Hazizan Md.; Noor, Ahmad Md.

    2010-01-01

    Carbon blacks (CB), derived from bamboo stem (BS-CB), coconut shells (CNS-CB) and oil palm empty fiber bunch (EFB-CB), were obtained by pyrolysis of fibers at 700 o C, characterized and used as filler in epoxy composites. The results obtained showed that the prepared carbon black possessed well-developed porosities and are predominantly made up of micropores. The BS-CB, CNS-CB and EFB-CB filled composites were prepared and characterized using scanning electron microscope (SEM) and thermogravimetric analyzer (TGA). The SEM showed that the fractured surface of the composite indicates its high resistance to fracture. The CBs-epoxy composites exhibited better flexural properties than the neat epoxy, which was attributed to better adhesion between the CBs and the epoxy resin. TGA showed that there was improvement in thermal stability of the carbon black filled composites compared to the neat epoxy resin.

  9. Non-axisymmetric flexural vibrations of free-edge circular silicon wafers

    Energy Technology Data Exchange (ETDEWEB)

    Dmitriev, A.V., E-mail: dmitriev@hbar.phys.msu.ru; Gritsenko, D.S.; Mitrofanov, V.P., E-mail: mitr@hbar.phys.msu.ru

    2014-02-07

    Non-axisymmetric flexural vibrations of circular silicon (111) wafers are investigated. The modes with azimuthal index 2⩽k⩽30 are electrostatically excited and monitored by a capacitive sensor. The splitting of the mode frequencies associated with imperfection of the wafer is observed. The measured loss factors for the modes with 6≲k≲26 are close to those calculated according to the thermoelastic damping theory, while clamping losses likely dominate for k≲6, and surface losses at the level of inverse Q-factor Q{sup −1}≈4×10{sup −6} prevail for the modes with large k. The modes demonstrate nonlinear behavior of mainly geometrical origin at large amplitudes.

  10. Finite element beam flexural properties of cement composites of fiber reinforced PVA

    Science.gov (United States)

    Yang, Chengzhi; Pei, Changchun

    2018-05-01

    In this paper, the initial cracking state and the mid span bending moment and deflection of ECC beam under different PVA fiber and fly ash mixing rate are studied by finite element simulation analysis. The results show that the bending moment of the ECC beam increases with the increase of the PVA fiber content, and the deflection decreases. When the ratio of PVA fiber is 1.5%, the middle bending moment is the largest and the deflection is the least. With the increase of fly ash content, the mid span bending moment of ECC beam increases first and then decreases. When the fly ash ratio is 60%, the middle bending moment is the largest and the deflection is the least. Through the study, the formula for calculating the flexural capacity of the cross section suitable for ECC beams is derived.

  11. Natural frequencies and forms of flexural vibrations of a beam with a crack

    Directory of Open Access Journals (Sweden)

    Gordon Vladimir Aleksandrovich

    2014-03-01

    Full Text Available In view of providing durability of constructions, the urgent problem is studying dynamic processes in loaded rod structures occurring in the process of sudden local defects formation, such as breakage of support bonds, partial destruction, transverse and longitudinal cracks etc., which are united under general term "beyond design impacts". To date, a number of problems related to this topic are solved: the problem of dynamic loadings at sudden formation of transverse cracks, the problem of partial tie breaks in the bearings, partial destruction and longitudinal lamination of compound bars. In the paper the authors propose a method of determining the spectrum of natural frequencies of flexural vibrations of a rod system with this type of injury. The results are to be used for modal analysis of forced vibrations of a beam with a defect of longitudinal lamination, depending on its level.

  12. Propagation of flexural waves in inhomogeneous plates exhibiting hysteretic nonlinearity: Nonlinear acoustic black holes.

    Science.gov (United States)

    Gusev, Vitalyi E; Ni, Chenyin; Lomonosov, Alexey; Shen, Zhonghua

    2015-08-01

    Theory accounting for the influence of hysteretic nonlinearity of micro-inhomogeneous material on flexural wave in the plates of continuously varying thickness is developed. For the wedges with thickness increasing as a power law of distance from its edge strong modifications of the wave dynamics with propagation distance are predicted. It is found that nonlinear absorption progressively disappearing with diminishing wave amplitude leads to complete attenuation of acoustic waves in most of the wedges exhibiting black hole phenomenon. It is also demonstrated that black holes exist beyond the geometrical acoustic approximation. Applications include nondestructive evaluation of micro-inhomogeneous materials and vibrations damping. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Design guidelines for flexural wave attenuation of slender beams with local resonators

    International Nuclear Information System (INIS)

    Liu, Yaozong; Yu, Dianlong; Li, Li; Zhao, Honggang; Wen, Jihong; Wen, Xisen

    2007-01-01

    The complex band structures and attenuation spectra of flexural waves in slender beams with periodically mounted local resonators are investigated with transfer matrix method. It is noteworthy that the frequency range and attenuation coefficient of the locally resonant gap become larger in complex band structures if larger resonators were used. But given the total add-on mass of resonators, the attenuation spectra of finite beams with large but few resonators do not demonstrate such phenomena because the attenuation needs several periods to establish. So with the view of application, a large number of small local resonators widely spread along the beam are preferred given the total add-on mass to the beam

  14. Triple degree-of-freedom piezoelectric ultrasonic micromotor via flexural-axial coupled vibration.

    Science.gov (United States)

    Khoo, Ter Fong; Dang, Dinh Huy; Friend, James; Oetomo, Denny; Yeo, Leslie

    2009-08-01

    Actuators remain a limiting factor in robotics, especially in microrobotics where the power density of actuators is a problem. A 3 x 3 x 8.7 mm 3-axis piezoelectric ultrasonic micromotor system is described here in an effort to help solve this problem. Formed from 4 bulk lead zirconate titanate (PZT) thickness-polarized elements placed around the periphery of a rectangular rod, the stator is designed to combine axial and flexural vibrations in a way that permits rotation of a hardened steel ball as a rotor about an arbitrary axis. A simple prototype of the micromotor was found to produce at least a rotation speed of 10.4 rad/s with 4 microN-m torque about all 3 orthogonal directions at an excitation frequency of about 221 kHz, demonstrating the feasibility of a 3 degree-of-freedom millimeter-scale piezoelectric motor.

  15. Calculating the Carrying Capacity of Flexural Prestressed Concrete Beams with Non-Metallic Reinforcement

    Directory of Open Access Journals (Sweden)

    Mantas Atutis

    2011-04-01

    Full Text Available The article reviews moment resistance design methods of prestressed concrete beams with fibre-reinforced polymer (FRP reinforcement. FRP tendons exhibit linear elastic response to rupture without yielding and thus failure is expected to be brittle. The structural behaviour of beams prestressed with FRP tendons is different from beams with traditional steel reinforcement. Depending on the reinforcement ratio, the flexural behaviour of the beam can be divided into several groups. The numerical results show that depending on the nature of the element failure, moment resistance calculation results are different by using reviewed methods. It was found, that the use of non-metallic reinforcement in prestressed concrete structures is effective: moment capacity is about 5% higher than that of the beams with conventional steel reinforcement.Article in Lithuanian

  16. Piezoelectric transduction of flexural modes in pre-stressed microbeam resonators

    Science.gov (United States)

    Torri, G. B.; Janssen, N. M. A.; Zeng, Z.; Rottenberg, X.; Karabacak, D. M.; Vandecasteele, M.; Van Hoof, C.; Puers, R.; Tilmans, H. A. C.

    2014-08-01

    This paper reports on the optimization of the design of piezoelectric transducer elements integrated on doubly-clamped microbeam resonators utilized as (bio)chemical sensors. We report and emphasize the often forgotten influence of membrane stresses on defining the dimensions and optimal position of the piezoelectric transducer elements. The study takes into account stress induced structural changes and provides models for the equivalent motional parameters of resonators with particular shapes of the transducers matching the flexural modes of vibration. The above is analyzed theoretically using numerical models and is confirmed by impedance measurements and optical measurements of fabricated doubly-clamped beam resonators. We propose various transducer designs and highlight the advantages of using higher order vibration modes by implementing specially designed mode matching transducer elements. It is concluded that the paper describes and highlights the importance of accounting for the membrane stresses to optimize the resonator performance and the low power in electronic feedback of resonating sensing systems.

  17. Design, analysis, and testing of a flexure-based vibration-assisted polishing device

    Science.gov (United States)

    Gu, Yan; Zhou, Yan; Lin, Jieqiong; Lu, Mingming; Zhang, Chenglong; Chen, Xiuyuan

    2018-05-01

    A vibration-assisted polishing device (VAPD) composed of leaf-spring and right-circular flexure hinges is proposed with the aim of realizing vibration-assisted machining along elliptical trajectories. To design the structure, energy methods and the finite-element method are used to calculate the performance of the proposed VAPD. An improved bacterial foraging optimization algorithm is used to optimize the structural parameters. In addition, the performance of the VAPD is tested experimentally. The experimental results indicate that the maximum strokes of the two directional mechanisms operating along the Z1 and Z2 directions are 29.5 μm and 29.3 μm, respectively, and the maximum motion resolutions are 10.05 nm and 10.01 nm, respectively. The maximum working bandwidth is 1,879 Hz, and the device has a good step response.

  18. A double-bent planar leaf flexure guide for a nano-scanner: experimental report

    International Nuclear Information System (INIS)

    Jeon, Jeong-Woo; Kim, Jong-Moon; Lee, Young-Hyoung; Lee, Dong-Yeon

    2014-01-01

    We describe an experimental study on the double-bent leaf flexure-guided nano-scanner introduced in a previous paper [J. Korean Phy. Soc. 57, 1581 (2010)]. The optimally-designed nanoscanner was fabricated. Its performances were verified using a finite element analysis (FEA). The nano-scanner is actuated by a voice coil motor. Its characteristics were measured with a laser interferometer. The first resonant frequency is calculated as 17.1 Hz. The performances of the nano-scanner, including sine tracking capability, a multi-step response, and range of travel check were evaluated using various experimental procedures. Test results reveal that the scanner traveled over a 4.0 mm range and had good nano-precision (4 nm).

  19. Research on the Fatigue Flexural Performance of RC Beams Attacked by Salt Spray

    Science.gov (United States)

    Mao, Jiang-hong; Xu, Fang-yuan; Jin, Wei-liang; Zhang, Jun; Wu, Xi-xi; Chen, Cai-sheng

    2018-04-01

    The fatigue flexural performance of RC beams attacked by salt spray was studied. A testing method involving electro osmosis, electrical accelerated corrosion and salt spray was proposed. This corrosion process method effectively simulates real-world salt spray and fatigue loading exerted by RC components on sea bridges. Four RC beams that have different stress amplitudes were tested. It is found that deterioration by corrosion and fatigue loading reduces the fatigue life of the RC and decreases the ability of deformation. The fatigue life and deflection ability could be reduced by increasing the stress amplitude and the corrosion duration time. The test result demonstrates that this experimental method can couple corrosion deterioration and fatigue loading reasonably. This procedure may be applied to evaluate the fatigue life and concrete durability of RC components located in a natural salt spray environment.

  20. Flexural Behavior of High-Volume Steel Fiber Cementitious Composite Externally Reinforced with Basalt FRP Sheet

    Directory of Open Access Journals (Sweden)

    Seungwon Kim

    2016-01-01

    Full Text Available High-performance fiber-reinforced cementitious composites (HPFRCCs are characterized by unique tensile strain hardening and multiple microcracking behaviors. The HPFRCC, which demonstrates remarkable properties such as strength, ductility, toughness, durability, stiffness, and thermal resistance, is a class of fiber cement composite with fine aggregates. It can withstand tensile stresses by forming distributed microcracks owing to the embedded fibers in the concrete, which improve the energy absorption capacity and apparent ductility. This high energy absorbing capacity can be enhanced further by an external stiff fiber-reinforced polymer (FRP. Basalt fabric is externally bonded as a sheet on concrete materials to enhance the durability and resistance to fire and other environmental attacks. This study investigates the flexural performance of an HPFRCC that is externally reinforced with multiple layers of basalt FRP. The HPFRCC considered in the study contains steel fibers at a volume fraction of 8%.

  1. Pretreatment of Woven Jute FRP Composite and Its Use in Strengthening of Reinforced Concrete Beams in Flexure

    Directory of Open Access Journals (Sweden)

    Tara Sen

    2013-01-01

    Full Text Available Environmental awareness motivates researchers worldwide to perform studies of natural fibre reinforced polymer composites, as they come with many advantages and are primarily sustainable. The present study aims at evaluating the mechanical characteristics of natural woven jute fibre reinforced polymer (FRP composite subjected to three different pretreatments, alkali, benzyl chloride, and lastly heat treatment. It was concluded that heat treatment is one of the most suitable treatment methods for enhancing mechanical properties of jute FRP. Durability studies on Jute FRP pertaining to some common environmental conditions were also carried out such as effect of normal water and thermal aging on the tensile strength of jute FRP followed by fire flow test. The heat treated woven jute FRP composites were subsequently used for flexural strengthening of reinforced concrete beams in full and strip wrapping configurations. The study includes the effect of flexural strengthening provided by woven jute FRP, study of different failure modes, load deflection behavior, effect on the first crack load, and ultimate flexural strength of concrete beams strengthened using woven jute FRP subjected to bending loads. The study concludes that woven jute FRP is a suitable material which can be used for flexural upgradation of reinforced concrete beams.

  2. Woven hybrid composites: Tensile and flexural properties of oil palm-woven jute fibres based epoxy composites

    Energy Technology Data Exchange (ETDEWEB)

    Jawaid, M. [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Abdul Khalil, H.P.S., E-mail: akhalilhps@gmail.com [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Abu Bakar, A. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2011-06-15

    Highlights: {yields} Woven hybrid composites show good tensile and flexural properties. {yields} Hybridization with 20% woven jute gives rise to sufficient modulus to composites. {yields} Layering pattern affect mechanical properties of hybrid composites. {yields} Statistical analysis shows that there is significant difference between composites. - Abstract: In this research, tensile and flexural performance of tri layer oil palm empty fruit bunches (EFB)/woven jute (Jw) fibre reinforced epoxy hybrid composites subjected to layering pattern has been experimentally investigated. Sandwich composites were fabricated by hand lay-up technique in a mould and cured with 105 deg. C temperatures for 1 h by using hot press. Pure EFB and woven jute composites were also fabricate for comparison purpose. Results showed that tensile and flexural properties of pure EFB composite can be improved by hybridization with woven jute fibre as extreme woven jute fibre mat. It was found that tensile and flexural properties of hybrid composite is higher than that of EFB composite but less than woven jute composite. Statistical analysis of composites done by ANOVA-one way, it showed significant differences between the results obtained. The fracture surface morphology of the tensile samples of the hybrid composites was performed by using scanning electron microscopy.

  3. Precision tool holder with flexure-adjustable, three degrees of freedom for a four-axis lathe

    Science.gov (United States)

    Bono, Matthew J [Pleasanton, CA; Hibbard, Robin L [Livermore, CA

    2008-03-04

    A precision tool holder for precisely positioning a single point cutting tool on 4-axis lathe, such that the center of the radius of the tool nose is aligned with the B-axis of the machine tool, so as to facilitate the machining of precision meso-scale components with complex three-dimensional shapes with sub-.mu.m accuracy on a four-axis lathe. The device is designed to fit on a commercial diamond turning machine and can adjust the cutting tool position in three orthogonal directions with sub-micrometer resolution. In particular, the tool holder adjusts the tool position using three flexure-based mechanisms, with two flexure mechanisms adjusting the lateral position of the tool to align the tool with the B-axis, and a third flexure mechanism adjusting the height of the tool. Preferably, the flexures are driven by manual micrometer adjusters. In this manner, this tool holder simplifies the process of setting a tool with sub-.mu.m accuracy, to substantially reduce the time required to set the tool.

  4. Woven hybrid composites: Tensile and flexural properties of oil palm-woven jute fibres based epoxy composites

    International Nuclear Information System (INIS)

    Jawaid, M.; Abdul Khalil, H.P.S.; Abu Bakar, A.

    2011-01-01

    Highlights: → Woven hybrid composites show good tensile and flexural properties. → Hybridization with 20% woven jute gives rise to sufficient modulus to composites. → Layering pattern affect mechanical properties of hybrid composites. → Statistical analysis shows that there is significant difference between composites. - Abstract: In this research, tensile and flexural performance of tri layer oil palm empty fruit bunches (EFB)/woven jute (Jw) fibre reinforced epoxy hybrid composites subjected to layering pattern has been experimentally investigated. Sandwich composites were fabricated by hand lay-up technique in a mould and cured with 105 deg. C temperatures for 1 h by using hot press. Pure EFB and woven jute composites were also fabricate for comparison purpose. Results showed that tensile and flexural properties of pure EFB composite can be improved by hybridization with woven jute fibre as extreme woven jute fibre mat. It was found that tensile and flexural properties of hybrid composite is higher than that of EFB composite but less than woven jute composite. Statistical analysis of composites done by ANOVA-one way, it showed significant differences between the results obtained. The fracture surface morphology of the tensile samples of the hybrid composites was performed by using scanning electron microscopy.

  5. Evolution of flexural rigidity according to the cross-sectional dimension of a superelastic nickel titanium orthodontic wire.

    Science.gov (United States)

    Garrec, Pascal; Tavernier, Bruno; Jordan, Laurence

    2005-08-01

    The choice of the most suitable orthodontic wire for each stage of treatment requires estimation of the forces generated. In theory, the selection of wire sequences should initially utilize a lower flexural rigidity; thus clinicians use smaller round cross-sectional dimension wires to generate lighter forces during the preliminary alignment stage. This assessment is true for conventional alloys, but not necessarily for superelastic nickel titanium (NiTi). In this case, the flexural rigidity dependence on cross-sectional dimension differs from the linear elasticity prediction because of the martensitic transformation process. It decreases with increasing deflection and this phenomenon is accentuated in the unloading process. This behaviour should lead us to consider differently the biomechanical approach to orthodontic treatment. The present study compared bending in 10 archwires made from NiTi orthodontics alloy of two cross-sectional dimensions. The results were based on microstructural and mechanical investigations. With conventional alloys, the flexural rigidity was constant for each wire and increased largely with the cross-sectional dimension for the same strain. With NiTi alloys, the flexural rigidity is not constant and the influence of size was not as important as it should be. This result can be explained by the non-constant elastic modulus during the martensite transformation process. Thus, in some cases, treatment can begin with full-size (rectangular) wires that nearly fill the bracket slot with a force application deemed to be physiologically desirable for tooth movement and compatible with patient comfort.

  6. Influence of nanoparticles on color stability, microhardness, and flexural strength of acrylic resins specific for ocular prosthesis.

    Science.gov (United States)

    Andreotti, Agda Marobo; Goiato, Marcelo Coelho; Moreno, Amália; Nobrega, Adhara Smith; Pesqueira, Aldiéris Alves; dos Santos, Daniela Micheline

    2014-01-01

    The aim of this study was to assess the effect of adding nanoparticles to N1 acrylic resin intended for artificial sclera, in terms of the color stability, microhardness, and flexural strength of the resin. Three hundred samples of N1 acrylic resin were used: 100 samples for color stability and microhardness tests (each test was performed on the opposite side of each sample), and 200 samples for flexural strength testing (100 samples before and after 1,008 hours of accelerated aging). Samples for each test were separated into ten groups (n=10), ie, without nanoparticles (control group) or with nanoparticles of zinc oxide, titanium dioxide (TiO₂), and barium sulfate at weight concentrations of 1%, 2%, and 2.5% (nanoparticle groups). Data were subjected to statistical analysis with nested analysis of variance and Tukey's test (P<0.05 significance level). Among the nanoparticle groups, the TiO₂ groups showed better color stability at all concentrations. Microhardness values increased after artificial aging, except for the control and zinc oxide groups. After aging, the 1%-2% TiO₂ groups had significantly higher microhardness values compared with the other nanoparticle groups. Before aging, there was a significant difference in flexural strength between the control and nanoparticle groups. After aging, the control and TiO₂ groups, regardless of concentration, showed the lowest flexural strength values. Incorporation of nanoparticles directly influenced the acrylic resin properties, with TiO₂ being the most influential nanoparticle in terms of the evaluated properties.

  7. Optimization of process variables on flexural properties of epoxy/organo-montmorillonite nanocomposite by response surface methodology

    Directory of Open Access Journals (Sweden)

    2008-01-01

    Full Text Available This study attempted to investigate the preparation and optimization of the flexural properties for epoxy/organomontmorillonite (OMMT nanocomposites. In-situ polymerization method was used to prepare epoxy/OMMT nanocomposites. The diglycidyl ether bisphenol A (DGEBA and curing agent were mixed first, followed by the addition of OMMT. In this study, computer aided statistical methods of experimental design (Response Surface Methodology, RSM was used to investigate the process variables on the flexural properties of epoxy/4wt% OMMT nanocomposites. Speed of mechanical stirrer, post-curing time and post-curing temperature were chosen as process variables in the experimental design. Results showed that the speed of mechanical stirrer, post-curing time and post-curing temperature were able to influence the flexural modulus and flexural yield stress of epoxy/4 wt% OMMT nanocomposites. The results of optimization showed that the design of experiment (DOE has six combination of operating variables which have been obtained in order to attain the greatest overall desirability.

  8. Characterization of the flexural behavior of a reactive graphitic nanofibers reinforced epoxy using a non-linear damage model

    Energy Technology Data Exchange (ETDEWEB)

    Jana, Soumen [Department of Mechanical Engineering and Applied Mechanics, North Dakota State University, Fargo, ND 58105 (United States); Zhong Weihong [Department of Mechanical Engineering and Applied Mechanics, North Dakota State University, Fargo, ND 58105 (United States)]. E-mail: Katie.zhong@ndsu.edu; Gan, Yong X. [Department of Mechanical Engineering, Albert Nerken School of Engineering, Cooper Union for the Advancement of Science and Art, 51 Astor Place, New York City, NY 10003 (United States)

    2007-02-15

    In our previous work, a nano-epoxy was developed based on the preparation of reactive graphitic nanofibers (r-GNFs). The objective of this work is to study the effect of the r-GNFs in an epoxy resin on the mechanical properties of the resulting nano-epoxy composites. Three-point bending tests were carried out for the pure epoxy and nano-epoxy materials with 0.15, 0.2, 0.3, 0.5 wt% r-GNFs to obtain the flexural behaviors. The nano-epoxy composite containing 0.3 wt% of r-GNFs showed the best flexural properties including highest flexural strength, modules and ductility values among all the tested materials. Non-linear fracture mechanics (NLFM) was applied to analyze the phenomena occurred during the bending tests. A non-linear damage model was used to interpret the flexural stress-strain relationships of the tested materials, which showed agreement with the testing results. The fracture surfaces of the nano-epoxy composites were examined with scanning electron microscopy (SEM), and the morphological features on the SEM images also reveals that the nano-epoxy composites are tougher than the pure epoxy resin.

  9. Flexural modeling of the elastic lithosphere at an ocean trench: A parameter sensitivity analysis using analytical solutions

    Science.gov (United States)

    Contreras-Reyes, Eduardo; Garay, Jeremías

    2018-01-01

    The outer rise is a topographic bulge seaward of the trench at a subduction zone that is caused by bending and flexure of the oceanic lithosphere as subduction commences. The classic model of the flexure of oceanic lithosphere w (x) is a hydrostatic restoring force acting upon an elastic plate at the trench axis. The governing parameters are elastic thickness Te, shear force V0, and bending moment M0. V0 and M0 are unknown variables that are typically replaced by other quantities such as the height of the fore-bulge, wb, and the half-width of the fore-bulge, (xb - xo). However, this method is difficult to implement with the presence of excessive topographic noise around the bulge of the outer rise. Here, we present an alternative method to the classic model, in which lithospheric flexure w (x) is a function of the flexure at the trench axis w0, the initial dip angle of subduction β0, and the elastic thickness Te. In this investigation, we apply a sensitivity analysis to both methods in order to determine the impact of the differing parameters on the solution, w (x). The parametric sensitivity analysis suggests that stable solutions for the alternative approach requires relatively low β0 values (rise bulge. The alternative method is a more suitable approach, assuming that accurate geometric information at the trench axis (i.e., w0 and β0) is available.

  10. [Effect of amount of silane coupling agent on flexural strength of dental composite resins reinforced with aluminium borate whisker].

    Science.gov (United States)

    Zhu, Ming-yi; Zhang, Xiu-yin

    2015-06-01

    To evaluate the effect of amount of silane coupling agent on flexural strength of dental composite resins reinforced with aluminium borate whisker (ABW). ABW was surface-treated with 0%, 1%, 2%, 3% and 4% silan coupling agent (γ-MPS), and mixed with resin matrix to synthesize 5 groups of composite resins. After heat-cured at 120 degrees centigrade for 1 h, specimens were tested in three-point flexure to measure strength according to ISO-4049. One specimen was selected randomly from each group and observed under scanning electron microscope (SEM). The data was analyzed with SAS 9.2 software package. The flexural strength (117.93±11.9 Mpa) of the group treated with 2% silane coupling agent was the highest, and significantly different from that of the other 4 groups (α=0.01). The amount of silane coupling agent has impact on the flexural strength of dental composite resins reinforced with whiskers; The flexual strength will be reduced whenever the amount is higher or lower than the threshold. Supported by Research Fund of Science and Technology Committee of Shanghai Municipality (08DZ2271100).

  11. The effect of casting conditions on the biaxial flexural strength of glass-ceramic materials.

    Science.gov (United States)

    Johnson, A; Shareef, M Y; Walsh, J M; Hatton, P V; van Noort, R; Hill, R G

    1998-11-01

    To assess the effect of mould and glass casting temperatures on the biaxial flexural strength (BFS) of two different types of castable glass-ceramic, using existing laboratory equipment and techniques. Two castable glass-ceramic materials were evaluated. One glass (LG3) is based on SiO2-Al2O3-P2O5-CaO-CaF2, and is similar in composition to glasses used in the manufacture of glass-ionomer cements. The other glass (SG3) is based on SiO2-K2O-Na2O-CaO-CaF2, and is a canasite-based material. Both materials were used to produce discs of 12 mm diameter and 2 mm thickness using the same lost-wax casting process as used for metal castings. Mould temperatures of between 500 degrees C and 1000 degrees C and glass casting temperatures of between 1100 degrees C and 1450 degrees C were evaluated. The cast discs were cerammed and the biaxial flexural strength determined with a Lloyd 2000 R tester. A significant difference was found for the BFS in the range of mould temperatures evaluated, with the optimum investment mould temperature being 590 degrees C for LG3 and 610 degrees C for SG3 (p = 0.0002 and p = 0.019, respectively). No significant differences were seen between any of the glass casting temperatures evaluated. The mould temperature for castable glass-ceramic materials produced using the lost-wax casting process can have a significant effect on BFS. The optimum mould temperature may differ slightly depending on the type of material being used. The glass casting temperature of these materials does not appear to have a significant effect on BFS.

  12. Gravity anomalies and flexure of the lithosphere at the Middle Amazon Basin, Brazil

    Science.gov (United States)

    Nunn, Jeffrey A.; Aires, Jose R.

    1988-01-01

    The Middle Amazon Basin is a large Paleozoic sedimentary basin on the Amazonian craton in South America. It contains up to 7 km of mainly shallow water sediments. A chain of Bouguer gravity highs of approximately +40 to +90 mGals transects the basin roughly coincident with the axis of maximum thickness of sediment. The gravity highs are flanked on either side by gravity lows of approximately -40 mGals. The observed gravity anomalies can be explained by a steeply sided zone of high density in the lower crust varying in width from 100 to 200 km wide. Within this region, the continental crust has been intruded/replaced by more dense material to more than half its original thickness of 45-50 km. The much wider sedimentary basin results from regional compensation of the subsurface load and the subsequent load of accumulated sediments by flexure of the lithosphere. The observed geometry of the basin is consistent with an elastic lithosphere model with a mechanical thickness of 15-20 km. Although this value is lower than expected for a stable cratonic region of Early Proterozoic age, it is within the accepted range of effective elastic thicknesses for the earth. Rapid subsidence during the late Paleozoic may be evidence of a second tectonic event or lithospheric relaxation which could lower the effective mechanical thickness of the lithosphere. The high-density zone in the lower crust, as delineated by gravity and flexural modeling, has a complex sinuous geometry which is narrow and south of the axis of maximum sediment thickness on the east and west margins and wide and offset to the north in the center of the basin. The linear trough geometry of the basin itself is a result of smoothing by regional compensation of the load in the lower crust.

  13. Investigation of the Processing Parameters Impact on the Flexural Tool Vibrations While Drilling

    Directory of Open Access Journals (Sweden)

    I. I. Ivanov

    2015-01-01

    Full Text Available The paper considers an approach to analyze a dynamic stability of the drilling process in terms of tool flexibility. The proposed technique takes into consideration a regenerative effect leading to time delay in the dynamic system. This regenerative delay is the main source of arising dynamically unstable machining conditions. The paper describes a principle of emerging self-vibrations while cutting. It mentions the undesirable nature of transverse bending selfvibrations of tool, which cause a decreasing quality of the processed hole surface.The suggested approach consists in building a diagram of the drilling process stability for a tool model allowing only its flexural vibrations. The feature of the study is to describe tool dynamics using a finite element model based on the quadratic approximation of displacements for tool dynamics modeling. The assumption of an axial symmetry of drill geometry was discarded. The reduced model of tool was built taking into account two eigenvectors corresponding to tool bending. This model contains 2 degrees of freedom (DOF, which are, essentially, rotations of a drill tip. The technology of rigid multi-point constraints was used to connect those DOFs with solid finite element nodes. The system of delayed differential equations describing the reduced tool model dynamics was derived to estimate a dynamic stability of the drilling process. The Floquet theory is applied to build a stability diagram as a maximum multiplicator value versus a drill rotation rate. The presented diagram allows us to draw a conclusion that in the wide range of rotation frequencies transverse bending self- vibrations can be excited. The results obtained and the calculation technique may be used to choose the operation modes free from undesirable flexural self-vibrations of tool.The reported study was supported by RFBR within the framework of the research project ” mol_a”№ 14-08-31603 “Development of methods and algorithms for

  14. Mars: Lithospheric Flexure of the Tharsis Montes Volcanoes and the Evolutionary Relationship to Their Tectonic History

    Science.gov (United States)

    Chute, H.; Dombard, A. J.; Byrne, P. K.

    2017-12-01

    Lithospheric flexure associated with Arsia, Pavonis, and Ascraeus Montes has been previously studied to constrain the timeline and breadth of endogenic surface features surrounding these volcanoes. Here, we simulate the radial extent of two specific load-related features: annular graben and flank terraces. Detailed mapping of Ascraeus Mons (the youngest of the three volcanoes) showed a phase of compression of the edifice, forming the terraces and an annulus of graben immediately off the flanks, followed by a period of extension that formed additional graben superposed on the terraces on the lower flanks of the edifice. This transition from compression to extension on the lower flanks has been difficult to reconcile in mechanical models. We explore, with finite-element simulations, the effects of a thermal anomaly associated with an intrusive crustal underplate, which results in locally thinning the lithosphere (in contrast to past efforts that assumed a constant-thickness lithosphere). We find that it is primarily the horizontal extent of this thermal anomaly that governs how the lithosphere flexes under a volcano, as well as the transition from flank compression to a tight annulus of extensional stresses. Specifically, we propose that the structures on Ascraeus may be consistent with an early stage of volcanic growth accompanied by an underplate about the same width as the edifice that narrowed as volcanism waned, resulting in an inward migration of the extensional horizontal stresses from the surrounding plains onto the lower flanks. By linking the surface strains on the volcano with the volcano-tectonic evolution predicted by our flexure model, we can further constrain a more accurate timeline for the tectonic history of Ascraeus Mons. More broadly, because these tectonic structures are commonly observed, our results provide a general evolutionary model for large shield volcanoes on Mars.

  15. Flexural resistance of Cerec CAD/CAM system ceramic blocks. Part 2: Outsourcing materials.

    Science.gov (United States)

    Sedda, Maurizio; Vichi, Alessandro; Del Siena, Francesco; Louca, Chris; Ferrari, Marco

    2014-02-01

    To test different Cerec CAD/CAM system ceramic blocks, comparing mean flexural strength (sigma), Weibull modulus (m), and Weibull characteristic strength (sigma0) in an ISO standardized set-up. Following the recent ISO Standard (ISO 6872:2008), 11 types of ceramic blocks were tested: IPS e.max CAD MO, IPS e.max CAD LT and IPS e.max CAD HT (lithium disilicate glass-ceramic); In-Ceram SPINELL, In-Ceram Alumina and In-Ceram Zirconia (glass-infiltrated materials); inCoris AL and In-Ceram AL (densely sintered alumina); In-Ceram YZ, IPS e.max Zir-CAD and inCoris ZI (densely sintered zirconia). Specimens were cut out from ceramic blocks, finished, crystallized/infiltrated/sintered, polished, and tested in a three-point bending test apparatus. Flexural strength, Weibull characteristic strength, and Weibull modulus were obtained. A statistically significant difference was found (P ceramic (sigma = 272.6 +/- 376.8 MPa, m = 6.2 +/- 11.3, sigma0 = 294.0 +/- 394.1 MPa) and densely sintered alumina (sigma = 441.8 +/- 541.6 MPa, m = 11.9 +/- 19.0, sigma0 = 454.2 +/- 565.2 MPa). No statistically significant difference was found (P = 0.254) in glass infiltrated materials (sigma = 376.9 +/- 405.5 MPa, m = 7.5 +/- 11.5, sigma0 = 393.7 +/- 427.0 MPa). No statistically significant difference was found (P = 0.160) in densely sintered zirconia (sigma = 1,060.8 +/- 1,227.8 MPa, m = 5.8 +/- 7.4, sigma0 = 1,002.4 +/- 1,171.0 MPa). Not all the materials tested fulfilled the requirements for the clinical indications recommended by the manufacturer.

  16. Silorane- and high filled-based"low-shrinkage" resin composites: shrinkage, flexural strength and modulus

    Directory of Open Access Journals (Sweden)

    Cesar Augusto Galvão Arrais

    2013-04-01

    Full Text Available This study compared the volumetric shrinkage (VS, flexural strength (FS and flexural modulus (FM properties of the low-shrinkage resin composite Aelite LS (Bisco to those of Filtek LS (3M ESPE and two regular dimethacrylate-based resin composites, the microfilled Heliomolar (Ivoclar Vivadent and the microhybrid Aelite Universal (Bisco. The composites (n = 5 were placed on the Teflon pedestal of a video-imaging device, and VS was recorded every minute for 5 min after 40 s of light exposure. For the FS and FM tests, resin discs (0.6 mm in thickness and 6.0 mm in diameter were obtained (n = 12 and submitted to a piston-ring biaxial test in a universal testing machine. VS, FS, and FM data were submitted to two-way repeated measures and one-way ANOVA, respectively, followed by Tukey's post-hoc test (a = 5%. Filtek LS showed lower VS than did Aelite LS, which in turn showed lower shrinkage than did the other composites. Aelite Universal and Filtek LS exhibited higher FS than did Heliomolar and Aelite LS, both of which exhibited the highest FM. No significant difference in FM was noted between Filtek LS and Aelite Universal, while Heliomolar exhibited the lowest values. Aelite LS was not as effective as Filtek LS regarding shrinkage, although both low-shrinkage composites showed lower VS than did the other composites. Only Filtek LS exhibited FS and FM comparable to those of the regular microhybrid dimethacrylate-based resin composite.

  17. Necrosis-Driven Systemic Immune Response Alters SAM Metabolism through the FOXO-GNMT Axis

    Directory of Open Access Journals (Sweden)

    Fumiaki Obata

    2014-05-01

    Full Text Available Sterile inflammation triggered by endogenous factors is thought to contribute to the pathogenesis of acute and chronic inflammatory diseases. Here, we demonstrate that apoptosis-deficient mutants spontaneously develop a necrosis-driven systemic immune response in Drosophila and provide an in vivo model for studying the organismal response to sterile inflammation. Metabolomic analysis of hemolymph from apoptosis-deficient mutants revealed increased sarcosine and reduced S-adenosyl-methionine (SAM levels due to glycine N-methyltransferase (Gnmt upregulation. We showed that Gnmt was elevated in response to Toll activation induced by the local necrosis of wing epidermal cells. Necrosis-driven inflammatory conditions induced dFoxO hyperactivation, leading to an energy-wasting phenotype. Gnmt was cell-autonomously upregulated by dFoxO in the fat body as a possible rheostat for controlling energy loss, which functioned during fasting as well as inflammatory conditions. We propose that the dFoxO-Gnmt axis is essential for the maintenance of organismal SAM metabolism and energy homeostasis.

  18. Hip resurfacing arthroplasty in treatment of avascular necrosis of the femoral head.

    Science.gov (United States)

    Pyda, Michał; Koczy, Bogdan; Widuchowski, Wojciech; Widuchowska, Małgorzata; Stołtny, Tomasz; Mielnik, Michał; Hermanson, Jacek

    2015-01-25

    Hip resurfacing is a conservative type of total hip arthroplasty but its use is controversial, especially in patients with osteonecrosis. The aim of this study was analysis of the clinical and radiographic outcomes of hip resurfacing in patients with osteonecrosis. Between 2007 and 2008, 30 hip resurfacing arthroplasties were performed due to osteoarthritis secondary to avascular necrosis of femoral head staged as Ficat III and IV. Patients were qualified to resurfacing arthroplasty when the extent of avascular necrosis using Kerboul's method was avascular necrosis and head-neck junction was >20°. All patients were evaluated clinically and radiologically before and 60 months after the operation. The mean Harris Hip Score (HHS) score increased from 47.8 to 94.25 (p<0.05). Physical activity level (University of California, Los Angeles activity score--UCLA activity score) improved from 3.7 to 7.55 (p<0.05). No implant migration was observed. Management of osteonecrosis of the hip with resurfacing arthroplasty seems to be effective in strictly-selected patients.

  19. A tissue engineering strategy for the treatment of avascular necrosis of the femoral head.

    Science.gov (United States)

    Aarvold, A; Smith, J O; Tayton, E R; Jones, A M H; Dawson, J I; Lanham, S; Briscoe, A; Dunlop, D G; Oreffo, R O C

    2013-12-01

    Skeletal stem cells (SSCs) and impaction bone grafting (IBG) can be combined to produce a mechanically stable living bone composite. This novel strategy has been translated to the treatment of avascular necrosis of the femoral head. Surgical technique, clinical follow-up and retrieval analysis data of this translational case series is presented. SSCs and milled allograft were impacted into necrotic bone in five femoral heads of four patients. Cell viability was confirmed by parallel in vitro culture of the cell-graft constructs. Patient follow-up was by serial clinical and radiological examination. Tissue engineered bone was retrieved from two retrieved femoral heads and was analysed by histology, microcomputed tomography (μCT) and mechanical testing. Three patients remain asymptomatic at 22- to 44-month follow-up. One patient (both hips) required total hip replacement due to widespread residual necrosis. Retrieved tissue engineered bone demonstrated a mature trabecular micro-architecture histologically and on μCT. Bone density and axial compression strength were comparable to trabecular bone. Clinical follow-up shows this to be an effective new treatment for focal early stage avascular necrosis of the femoral head. Unique retrieval analysis of clinically translated tissue engineered bone has demonstrated regeneration of tissue that is both structurally and functionally analogous to normal trabecular bone. Copyright © 2013 Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. Published by Elsevier Ltd. All rights reserved.

  20. The JCR:LA-cp rat: a novel rodent model of cystic medial necrosis.

    Science.gov (United States)

    Pung, Yuh Fen; Chilian, William M; Bennett, Martin R; Figg, Nichola; Kamarulzaman, Mohd Hamzah

    2017-03-01

    Although there are multiple rodent models of the metabolic syndrome, very few develop vascular complications. In contrast, the JCR:LA-cp rat develops both metabolic syndrome and early atherosclerosis in predisposed areas. However, the pathology of the normal vessel wall has not been described. We examined JCR:LA control (+/+) or cp/cp rats fed normal chow diet for 6 or 18 mo. JCR:LA-cp rats developed multiple features of advanced cystic medial necrosis including "cysts," increased collagen formation and proteoglycan deposition around cysts, apoptosis of vascular smooth muscle cells, and spotty medial calcification. These appearances began within 6 mo and were extensive by 18 mo. JCR:LA-cp rats had reduced medial cellularity, increased medial thickness, and vessel hypoxia that was most marked in the adventitia. In conclusion, the normal chow-fed JCR:LA-cp rat represents a novel rodent model of cystic medial necrosis, associated with multiple metabolic abnormalities, vascular smooth muscle cell apoptosis, and vessel hypoxia. NEW & NOTEWORTHY Triggers for cystic medial necrosis (CMN) have been difficult to study due to lack of animal models to recapitulate the pathologies seen in humans. Our study is the first description of CMN in the rat. Thus the JCR:LA-cp rat represents a useful model to investigate the underlying molecular changes leading to the development of CMN. Copyright © 2017 the American Physiological Society.