Analytical and Numerical Modelling of Creep Deformation of Viscoelastic Thick-Walled Cylinder with Fractional Maxwell Model

The deformation of a thick-walled cylinder under pressure is a classic elastic mechanics problem with various engineering applications. In this study, the displacement of a viscoelastic thick-walled cylinder under internal pressure is investigated via analytical as well as numerical modelling. The fractional Maxwell model is initially introduced to describe the creep deformation of high-strength Q460 steel. Subsequently, an analytical solution to the creep deformation of the thick-walled cylinder under both internal and external pressures is deduced with the corresponding principle. The analytical solution is examined with a numerical simulation that incorporates the fractional Maxwell model by a user-defined subroutine. The numerical simulation agrees well with the analytical solution. The limitations of the current study are also discussed.     

Fatigue Modeling and Numerical Analysis of Re-Filling Probe Hole of Friction Stir Spot Welded Joints in Aluminum Alloys

In the present study, the fatigue behavior and tensile strength of A6061-T4 aluminum alloy, joined by friction stir spot welding (FSSW), are numerically investigated. The 3D finite element model (FEM) is used to analyze the FSSW joint by means of Abaqus software. The tensile strength is determined for FSSW joints with both a probe hole and a refilled probe hole. In order to calculate the fatigue life of FSSW joints, the hysteresis loop is first determined, and then the plastic strain amplitude is calculated. Finally, by using the Coffin-Manson equation, fatigue life is predicted. The results were verified against available experimental data from other literature, and a good agreement was observed between the FEM results and experimental data. The results showed that the joint’s tensile strength without a probe hole (refilled hole) is higher than the joint with a probe hole. Therefore, re-filling the probe hole is an effective method for structures jointed by FSSW subjected to a static load. The fatigue strength of the joint with a re-filled probe hole was nearly the same as the structure with a probe hole at low applied loads. Additionally, at a high applied load, the fatigue strength of joints with a refilled probe hole was slightly lower than the joint with a probe hole.     

Continuous flow method for determination of erythrocyte osmotic fragility

A simple and accurate micromethod for the determination of erythrocyte osmotic fragility is introduced. The method uses a laminar parabolic flow pattern, together with gravity, to retain cells in a long, small-diameter tube while a solution with decreasing osmolarity is passed through the tube. As the cells hemolyze, hemoglobin released from the cells is quickly removed by the axial flow pattern and monitored with a 547 nm optical detector for recording the hemolysis curve. Consequently, a continuous curve is obtained, with a peak occurring at the salt concentration that produces the maximum hemolysis rate. The advantages of this method are simplicity, accuracy, and small sample size (2 microliters of whole blood). The small sample size is of particular importance for infants. A comparison is made with the Parpart method using samples from 18 normal adults. Results are also given for a few abnormal adults and for a series of 26 normal newborns.     

Fractional exhaled nitric oxide measurement with a handheld device

A sensing system for fractional exhaled nitric oxide (FeNO) measurement is presented, which is characterized by a compact setup and a cost potential to be made available for the patient at home. The sensing is based on the work function measurement of a phthalocyanine-type sensing material, which is shown to be sufficiently sensitive for NO(2) in the ppb range. The transducer used to measure the work function is a field effect transistor with a suspended gate electrode. Selectivity is given with respect to other breath components including typically metabolic by-products. The measurement system includes breath treatments in a simple setup, which essentially are dehumidification and a quantitative conversion of NO to NO(2) with a conversion rate of approx. 95%, using a disposable oxidation catalyst. The accomplishment of the correct exhalation maneuver and feeding of the suited portion of exhaled air to the sensor is provided by breath sampling means. The sensor is not gas consuming. This allows us to fill the measurement chamber once, instead of establishing a gas flow for the measurement. This feature simplifies the device architecture. In this paper, we report on sensor characteristics, system architecture and measurement with artificial breath-gas as well as with human breath with the device.     

Salmonella hepatitis

Typhoid fever is often associated with abnormal liver biochemical tests, but severe hepatic involvement with a clinical feature of acute hepatitis is a rare complication. There have been more than 150 cases of salmonella hepatitis reported from both developed and developing countries. The documented incidence varies widely from less than 1% to 26% of patients with enteric fever. The possible associated factors for development of salmonella hepatitis are virulence of the organisms, delayed treatment and poor general health of the patients. The pathogenesis of severe hepatic involvement in salmonella infection may be multifactorial and includes endotoxin, local inflammatory and/or host immune reactions. Clinical jaundice in salmonella hepatitis usually occurs within the first 2 weeks of the febrile illness. Hepatomegaly and moderate elevation of transaminase levels are common findings. Extreme hepatic dysfunction with hepatic encephalopathy is a rare coexisting complication in salmonella hepatitis. A positive culture for salmonella from blood or stool is essential to differentiate salmonella hepatitis from other causes of acute hepatitis. Hepatic pathology is characterized by the presence of typhoid nodules with marked hyperplasia of reticuloendothelial cells. The prognosis is usually good as salmonella hepatitis responds well to a specific antibiotic therapy and jaundice resolves with clinical improvement. The clinical course can be severe with a mortality rate as high as 20%, particularly with delayed treatment or in patients with other complications of salmonella infection. As enteric fever is a common infection, the recognition of salmonella hepatitis is of clinical importance.     

Role of angioplasty in the treatment of renal artery stenosis

Atherosclerotic renal artery stenosis is frequent and is associated with a high incidence of morbidity and mortality, with a strong correlation with coronary artery disease, (Kalra et al., 2005; Cheung et al., 2002; Guo et al., 2007 [1], [2] and [3]). The atherosclerotic renal artery stenosis is an independent predictive factor of death (Conlon et al., 1998 [4]). The treatment of this lesion does not have strong evidence. A lot of studies in this area suggest the angioplasty is superior in a big majority between surgery, and angioplasty with stent is superior between balloon angioplasty, but some studies fail to prove the superiority of angioplasty versus medical treatment. These studies have sadly a lot of mistakes and nowadays we don’t know what is the treatment for our patients in a lot of cases. The angioplasty is indicated when there is a failure of antihypertensive medications for control of blood pressure, when it is associated with a renal insufficiency quickly progressive or when there is a lesion on each renal artery. Other studies must be organized for prove the superiority of angioplasty when there is a real stenosis, maybe with the use of fractional flow reserve.     

SEM studies on the copulatory apparatus of male Oesophagostomum columbianum

Summary SEM studies on the cloacal opening of Oesophagostomum columbianum indicate that it is located on a raised conical structure called the “genital cone”. The genital cone is provided with a ventral lip and a pair of subdorsal gential appendages. The vental lip is a triangular structure having a single papilla on it and the genital appendages are covered with wrinkled cuticle with a nerve process projecting to the exterior in center. The bursa is supported by muscular rays which end up as knob-like sessile genital papillae. The inner surface of the bursa is porous. Spicules are two, equal, each provided with an ala which decreases in height distally and end up much prior to the spicular tip.     

Anovaginal Reconstruction with Bilateral X-Flaps and Sphincteroplasty for Cloaca-Like Deformity After Obstetrical Injury

Purpose Up to 0.3 percent of complicated vaginal deliveries may result in a cloaca-like deformity with debilitating incontinence and symptoms similar to a rectovaginal fistula because of the lack of the distal rectovaginal septum. This video illustrates the surgical technique of an anovaginal and perineal reconstruction with X-flaps and sphincteroplasty without primary fecal diversion. Methods The patients are placed in prone jackknife position. The flaps are marked with a pen. The junction/contact zone between rectal and vaginal mucosa is incised and the septum dissected up to the puborectalis muscle. The X-flaps are mobilized bilaterally. The posterior wall of the vagina and the anterior wall of the anal canal are then reconstructed with two suture layers each. Subsequently, an overlapping sphincteroplasty is performed and the puborectalis muscle centrally approximated. The flaps are then transposed beyond the midline to rebuild a perineal body. For all deeper reconstruction steps, 2/0 polyglactin 910 sutures (Vicryl?, Ethicon Inc., Somerville, NJ) are used; the skin is closed with running subcuticular sutures of poliglecaprone 25 (Monocryl?, Ethicon Inc.). In the end, the patient has regained a circumferentially proper length of the anal canal and the vagina, a closed ring of the anal sphincter, and a reconstructed perineal body with separation of anus and vagina. Conclusions Cloaca-like deformity resulting from severe obstetrical injury is the worst and most debilitating form of sphincter injuries but often is not given appropriate attention. Reconstruction of the original anatomy is more complex than a simple sphincteroplasty, but a prophylactic fecal diversion is usually not necessary. The reseparation of the rectum and the vagina in conjunction with a sphincteroplasty achieves good results. The online version of this article (DOI: ) contains supplementary material, which is available to authorized users. This multimedia article (video) has been published online and is available for viewing at . As a subscriber to Diseases of the Colon & Rectum, you have access to our SpringerLink electronic service, including Online First. Poster presentation at the meeting of The American Society for Colon and Rectal Surgeons, Philadelphia, Pennsylvania, April 30 to May 5, 2005.     

Electrophysiology studies in patients with dilated cardiomyopathies

Dilated cardiomyopathy is a diverse group of heart diseases with variable arrhythmia substrates. The response to programmed stimulation is dependent on spontaneous arrhythmia presentation. In patients with dilated cardiomyopathy, the majority of sustained monomorphic VT is caused by a scar-related reentrant mechanism, similar to that of coronary artery disease. The arrhythmia is uniformly inducible and is often refractory to pharmacologic therapy. Sustained VT is associated with more extensive myocardial fibrosis and non-uniform anisotropy, involving both the endocardium and epicardium, compared to those without sustained reentry. The response to programmed stimulation is more variable in patients presenting with nonsustained arrhythmia, cardiac arrest or syncope. Inducibility of monomorphic VT is much lower compared to those with ischemic heart disease. Other non-reentrant mechanism, such as focal automaticity, can also be observed in patients with monomorphic VT, in the absence of myocardial scar or evidence of slow conduction. The utility of electrophysiology studies to determine prognosis and to guide therapy remains limited in this patient population. The clinical outcome does not correlate with arrhythmia inducibility, and suppression of induced arrhythmia does not predict a good prognosis. The diagnosis of sarcoidosis or Chagas' cardiomyopathy should be considered in patients with dilated cardiomyopathy of unknown etiology, particularly in those with marked regional wall motion abnormalities and inducible VT. Epicardial reentrant circuits may be more prevalent in these cardiomyopathies, especially in those with VT related to chronic Chagas' disease. Although bundle branch reentry VT is a common finding in patients with dilated cardiomyopathy, it can occur in cardiomyopathy of any type and may coexist with other myocardial reentrant VT. It often has a typical bundle branch block QRS pattern during VT and is associated with His-Purkinje conduction delay. Evidence of macroreentry involving the bundle branches can usually be demonstrated, and catheter ablation of the bundle branches provides an effective and specific treatment.     

Colangitis esclerosante primaria: diagnóstico, pronóstico y tratamiento

Primary sclerosing cholangitis is a chronic cholestatic disease characterized by inflammation with fibrosis and obliteration of the intra- and extrahepatic bile ducts. This disease is usually associated with ulcerative colitis. The process of chronic cholestasis eventually leads to biliary cirrhosis. The prevalence of primary sclerosing cholangitis is low in southern Europe but is especially high in Scandinavian countries.The etiopathogenesis is unknown but immune disorders, potential toxic agents or intestinal infections, ischemic injury to the bile ducts, and possibly alterations in hepatobiliary transporters are known to play a role. The disease manifests at the age of approximately 40 years, mainly in men with clinical and laboratory features of cholestasis but may also be asymptomatic.There are specific forms in which the small intrahepatic bile ducts are involved, mainly affecting children, as well as overlap syndromes with autoimmune hepatitis. A form characterized by an increase in IgG4 has been described, which is usually associated with autoimmune pancreatitis.The key diagnostic procedure is endoscopic retrograde cholangiography, although magnetic resonance cholangiography is the first diagnostic procedure that should be used since it is equally informative and non-invasive. Liver biopsy is not essential for diagnosis. Primary sclerosing cholangitis is a progressive disease with a probability of transplant-free survival of 18 years in asymptomatic forms and of 8.5 years in symptomatic forms. Cholangiocarcinoma can result from the disease and confers a poor prognosis. There is no specific treatment although ursodeoxycholic acid improves the biochemical alterations of cholestasis.Liver transplantation is the last therapeutic resort with good results in terms of survival although the disease can recur in the transplanted liver.     

Actinomycosis, A Rare and Unsuspected Cause of Anal Fistulous Abscess: Report of Three Cases and Review of the Literature

. Primary perianal actinomycosis is rare. Sporadic cases, with lesions varying in extent have been reported. The infection is caused by the bacterium Actinomyces, which often is a saprophyte. Male gender and diabetes are risk factors, but the exact pathogenic mechanism remains speculative. The diagnosis is a challenge and often delayed, with a protracted history of masses and sinuses extending into the gluteal and genital region. The treatment, a combination of surgery and antibiotics, is poorly standardized. We report three cases and compare their characteristics to those of published cases, found by a computerized literature search (1968–2002).The lesions, a simple fistula-in-ano or a mass, were diagnosed in an early stage in all three patients. The infection always spread into the scrotum. There were no risk factors other than gender, except in one patient. The diagnosis was suspected by the observation of draining sulfur granules and promptly confirmed by histology in the three cases. All patients healed with antibiotics in addition to simple surgical procedures. Treatment consisted of amoxicillin for two weeks in two cases and more extended antimicrobial treatment in the third. These findings are contrasting with the classic picture of perianal actinomycosis.It is concluded that perianal actinomycosis can occur in the absence of risk factors and that early diagnosis requires a high degree of suspicion. An infection with Actinomyces should be suspected in the presence of lesions containing watery purulent material with sulfur granules. The indication for extended antibiotherapy combined with sphincter damaging surgery may need to be revised in the presence of early detection.     

A cylinder-shaped balloon catheter for the management of dissecting aneurysms in acute stage.

We developed a new procedure to close the entry of dissecting aneurysm in acute stage with a specially designed cylinder-shaped balloon catheter. The balloon catheter consists of 7F double lumen catheter and a silicone rubber balloon at the tip. The balloon has a central tube 14 mm caliber made of rigid silicone and it inflates into the shape of a cylinder with an injected solution. The central tube serves as a route for maintaining the aortic blood flow to the distal site. The catheter with a deflated balloon is inserted into the thoracic aorta ascendingly through a 14 or 16 mm caliber Dacron vascular graft sutured at the side of the distal aorta in a similar manner to intra-aortic balloon pumping. The tip of the catheter is carried to the entry tear of the pseudo-lumen. Then the cylinder-shaped balloon is inflated with solution. The entry is, therefore, closed with the side wall of the balloon and the blood stream into the dissected lumen is occluded while maintaining an aortic blood flow to the distal site. To prevent any possible occlusion due to thrombosis, some type of anticoagulant is administered via the catheter connected to a continuous injector. The healing process of the dissected lumen can be enhanced by injecting some type of coagulant directly into the lumen. The treatment is completed when the blood in the false lumen coagulates and stabilizes. The cylinder-shaped balloon is then deflated and the catheter withdrawn. The graft is removed and the stump is sutured.(ABSTRACT TRUNCATED AT 250 WORDS)     

Contained rupture of left ventricular false aneurysm after acute myocardial infarction secondary to left anterior descending artery embolism

Left ventricular free wall rupture is a rare complication of acute myocardial infarction and accounts for a significant number of fatalities. Pseudoaneurysm is a variety of left ventricular rupture whereby the pericardium seals the defect, forming the wall of the pseudoaneurysm. The diagnosis is usually confirmed with echocardiography, and emergent surgical repair is required in suspected impending rupture. The present report describes the case of a 58-year-old woman who presented with a myocardial infarction due to distal left anterior descending artery occlusion, complicated by ventricular pseudoaneurysm with impending rupture. The patient had an otherwise normal coronary tree.     

Acute cardiac insufficiency and toxoplasmosis

The authors report the case of a 21-year old, non-immunocompromised girl who presented with severe acute heart failure associated with Toxoplasma infection. The outcome was favourable: cure without sequelae was obtained in a few months with a symptomatic and specific treatment consisting of spiramycin and methylprednisolone. This case is interesting for several reasons. The occurrence of such an acute heart disease is extremely rare in patients with toxoplasmic myocarditis, and so is the presence of a septal focus suspected on the basis of a predominantly septal hypokinesia at echocardiography and of enzymatic changes. The development of an acute heart failure should suggest a diagnosis of toxoplasmic myocarditis, which is rare but important since a specific treatment is available.     

Three new applicators for hyperthermia

A computerized system with automatic treatment parameters control for radiological hyperthermia, called Sapic SV03, is presented. The system has been planned and built by the "Sezione Avionica ed Equipaggiamenti" of the Aeritalia in cooperation with the Radiotherapy Department of the University of Turin. The device is supplied with a multifrequency generator system (915, 433, 2-30 MHz) connected with many kinds of applicators, with a fiber optic system for temperature control and a previsional thermometry system. In this paper the authors presented three new applicators. The first one is a concave parallel microstrip applicator at 433 MHz, with a size 16 x 9 cm; the heating pattern is homogenous until 4 cm of depth. This antenna can be used for the treatment of chest wall recurrences of breast cancer. The second is a 27 MHz inductive ring and the third applicator is a pyramidal antenna ("TEM line") that operates at a frequency around 27 MHz.     

Multiple myeloma terminating in lymphocytic leukemia with B-lymphocyte membrane markers

The development of lymphocytic leukemia with a rapidly fatal clinical course is reported in a patient with kappa light-chain multiple myeloma treated with alkeran. The leukemic cells lacked the ultrastructural features of plasma cells but bore readily detectable B-cell markers and resembled lymphocytes under the light, transmission, and scanning electron microscopes. The leukemic phase is perhaps best defined as lymphocytic and probably represents a variant of plasma cell leukemia, in which the cells showed a degree of dedifferentiation from plasma cells to B lymphocytes. The possible relation between these 2 proliferative processes is discussed and the nature of leukemias developing in cases of plasma cell myeloma is briefly reviewed.     

Relapsing pleural exudate complicating chronic pancreatitis

Chronic pancreatitis, often with a pseudocyst, is a rare cause of a pleural exudate. A pancreatic pleural fistula is created, leading to a relapsing massive haemorrhagic pleural exudate with a very high amylase content. The diagnosis is confirmed by means of endoscopic retrograde pancreatography. Treatment is primarily conservative; surgical drainage is sometimes necessary. The prognosis is generally favourable. The case history of a young woman with this condition is presented.     

Far-Field Subwavelength Straight-Line Projection/Imaging by Means of a Novel Double-Near-Zero Index-Based Two-Layer Metamaterial

In this paper, for the first time, tuned near-zero-index materials are used in a structure for the long-distance projection of very closely spaced objects with subwavelength separation. Near-zero-index materials have never been used for subwavelength projection/imaging. The proposed novel structure is composed of a two-layer slab that can project two slits with a subwavelength separation distance to a long distance without diverged/converged interference of the two imaged waves. The two-layer slab consists of a thin double-near-zero (DNZ) slab with an obtained tuned index of 0.05 and thickness of 0.04λ₀ coupled with a high-index dielectric slab with specific thicknesses. Through a parametric study, the non-zero index of the DNZ layer is tuned to create a clear image when it is coupled with the high-index dielectric layer. The minimum size for the aperture of the proposed two-layer slab is 2λ₀ to provide a clear projection of the two slits. The space between the slits is λ₀/8, which is five times beyond the diffraction limit. It is shown that, through the conventional methods (e.g., only with high-index dielectric slabs, uncoupled with a DNZ layer), it is impossible to clearly project slits at a large distance (~λ₀) due to the diffraction limit. An analytical analysis, as well as numerical results in a finite-element-based simulator, confirm the function of the proposed structure.     

Demonstration of Use of a Novel 3D Printed Simulator for Mitral Valve Transcatheter Edge-to-Edge Repair (TEER)

Mitral regurgitation is a common valvular disorder. Transcatheter edge-to-edge repair (TEER) is a minimally invasive technique which involves holding together the middle segments of the mitral valve leaflets, thereby reducing regurgitation. To date, MitraClip™ is the only Food and Drug Administration (FDA)-approved device for TEER. The MitraClip procedure is technically challenging, characterised by a steep learning curve. Training is generally performed on simplified models, which do not emphasise anatomical features, realistic materials, or procedural scenarios. The aim of this study is to propose a novel, 3D printed simulator, with a major focus on reproducing the anatomy and plasticity of all areas of the heart involved and specifically the ones of the mitral valve apparatus. A three-dimensional digital model of a heart was generated by segmenting computed tomography (CT). The model was subsequently modified for: (i) adding anatomical features not fully visible with CT; (ii) adapting the model to interact with the MitraClip procedural equipment; and (iii) ensuring modularity of the system. The model was manufactured with a Polyjet technology printer, with a differentiated material assignment among its portions. Polypropylene threads were stitched to replicate chordae tendineae. The proposed system was successfully tested with MitraClip equipment. The simulator was assessed to be feasible to practice in a realistic fashion, different procedural aspects including access, navigation, catheter steering, and leaflets grasping. In addition, the model was found to be compatible with clinical procedural imaging fluoroscopy equipment. Future studies will assess the effect of the proposed training system on improving TEER training.     

Thrombotic thrombocytopenic purpura--still a therapeutic problem. Case report of a patient on long-term therapy

Thrombotic thromboctopenic purpura is a rare multisystemic life threatening disease the treatment of which is still a serious problem. The most successful therapy is plasmapheresis where the whole plasma volume of the patient is replaced by fresh frozen plasma or cryosupernatant. The authors describe a 34-year-old patient with the chronic relapsing form of the disease and repeated cerebrovascular attacks with an ischaemic genesis with developed organic psychosyndrome. The only effective treatment of the patient are exchange plasmaphereses replacing plasma by cryosupernatant after the patient became refractory to fresh frozen plasma. The authors describe the clinical development of the disease, its treatment by plasmaphereses and mention various ways of a venous approach and associated problems. Ensuring a venous approach in patients with this disease is of vital importance and in the terminal stage of the disease it is extremely difficult. A solution, though temporary, is implantation of a vascular prosthesis, Diastat. The functioning of the implant in this disease is however greatly threatened by the development of thrombotic occlusions.