Rheumatic tricuspid valve disease: Repair versus Replacement

Background: Tricuspid valve disease is most commonly functional, however, organic affection still accounts for one fourth of cases. Rheumatic fever which is endemic in Egypt is a main cause of organic affection. Current practice largely relies on tricuspid valve repair; however, it has been difficult to determine optimal procedure. Objectives: Herein, we study the outcome of replacement versus repair in such patients. Patients and methods: A prospective study was conducted on 300 consecutive patients with rheumatic heart disease showing severe tricuspid valve affection underwent tricuspid valve surgery, between 2014 and 2018. The patients were divided into two groups; TVR group (n=150) which included patients who underwent tricuspid valve replacement and TVr group (n=150) which included patients who underwent tricuspid valve repair. Diagnosis and follow up were done by echocardiography. Peri-operative variables, clinical outcome, morbidity, mortality, and follow up data were recorded. Results: Mean follow-up was 4±1.32 years. In-hospital mortality was 6 patients (4%) in TVR group and 3 patients (2%) in TVr group (P value ≥ 0.05). Postoperative low cardiac output syndrome and stroke were significantly higher in the repair group. Postoperative RV dysfunction, renal impairment, renal failure and chest re-exploration were significantly higher in the replacement group. Severe tricuspid regurgitation was reported in 19 patients (12.6%) of the repair group on follow up. Conclusion: Tricuspid valve repair is preferable to replacement to avoid the drawbacks of prosthesis. However, tricuspid valve replacement is feasible with comparable survival outcome and the progressive nature of the rheumatic disease may recommend replacement

Stabilizacja Na-bentonitu przez adsorpcję poli (chlorku diallilodimetyloamoniowego)

Clay minerals have been modified by polymers for different applications. .e polymer addition affects not only the surface properties but also the rheological properties and the stability of the clay-polymer suspension as a whole. In the current study, the electro-chemical properties of bentonite particles in presence of poly diallyl dimethyl ammonium chloride (PDDACl) were investigated. .ese properties were characterized by as zeta potential, adsorption isotherm, Fourier transform infrared (FTIR) and the apparent viscosity at different solid percent. .e results indicated that the viscosity of the bentonite-PDDACl suspension not only increases by raising the polymer concentration but also by increasing solids %. Adsorption of PDDACl polymer increases the positivity of bentonite surface as a function of polymer concentration, which could be explained mainly by electrostatic interaction of deficient metal ions at the octahedral sheets of bentonite with the cationic head group of the polymer. .e PDDACl adsorption isotherm on bentonite fits more probably Langmuir than Freundlich isotherm.Minerały ilaste zostały zmodyfikowane przez dodatek polimerów do rożnych zastosowań. Dodatek polimeru wpływa nie tylko na właściwości powierzchni, ale również na właściwości reologiczne i stabilność zawiesiny glina-polimer jako całości. W niniejszej pracy zbadano właściwości elektrochemiczne cząstek bentonitu w obecności chlorku polidiallilodimetyloamoniowego (PDDACl). Właściwości te scharakteryzowano jako potencjał zeta, izotermę adsorpcji, podczerwień z transformacją Fouriera (FTIR) oraz lepkość pozorną przy rożnych zawartościach fazy stałej. Wyniki wskazały, że lepkość zawiesiny bentonit-PDDACl wzrasta nie tylko wraz ze wzrostem stężenia polimeru, ale także ze wzrostem udziału fazy stałej. Adsorpcja polimeru PDDACl zwiększa dodatniość powierzchni bentonitu w funkcji stężenia polimeru, co można tłumaczyć głownie oddziaływaniem elektrostatycznym deficytowych jonów metali na oktaedrycznych arkuszach bentonitu z kationową grupą polimeru. Izoterma adsorpcji PDDACl na bentonicie pasuje bardziej do izotermy Langmuira niż izotermy Freundlicha

IN-SITU MINING OF PHOSPHATE ORES

Presently the mining of Florida phosphate requires the movement of over a 100-ton of materials (overburden, sand, clay) for every ton of phosphate concentrate recovered. Not only is this energy intensive, but it also causes significant stress on the environment. In 2003, the Department of Energy solicited ideas for innovative mining ideas that could significantly improve the efficiency of mining. An award was made to the University of Florida Engineering Research Center to evaluate the in situ mining of phosphates using an aqueous CO{sub 2} solution. Tests were carried out in a 15.2 cm (6-inch) diameter column, 1.83 meter (6 feet) long at pressures up to 117.2 kg/cm{sup 2} (40 psi). Results to date demonstrate that initially the MgO is leached from the ore and then the phosphate. While the tests are continuing, so far they have not demonstrated P{sub 2}O{sub 5} concentrations that are economically attractive

Bending, Buckling and Vibration of a Functionally Graded Porous Beam Using Finite Elements

This study presents the effect of porosity on mechanical behaviors of a power distribution functionally graded beam. The Euler-Bernoulli beam is assumed to describe the kinematic relations and constitutive equations. Because of technical problems, particle size shapes and micro-voids are created during the fabrication which should be taken into consideration. Two porosity models are proposed. The first one describes properties in the explicit form as linear functions of the porosity parameter. The second is a modified model which presents porosity and Young’s modulus in an implicit form where the density is assumed as a function of the porosity parameter and Young’s modulus as a ratio of mass with porosity to the mass without porosity. The modified proposed model is more applicable than the first model. The finite element model is developed to solve the problem by using the MATLAB software. Numerical results are presented to show the effects of porosity on mechanical behaviors of functionally graded beams

Importance of accurate diagnosis using real-time three-dimensional echocardiography in the surgical treatment of congenital intramitral ring in infants

Congenital mitral ring is a rare type of congenital mitral stenosis. There are two types of mitral ring: the intramitral ring and the supramitral ring. Intramitral rings are often associated with complex valve pathology, and therefore have a worse prognosis than supramitral rings, in which the mitral apparatus is usually normal. The role of echocardiography in the evaluation of the mitral valve apparatus is crucial, because it allows an identification of the types of malformation, their hemodynamic repercussion and early predictors of the outcome. We describe two cases of intramitral ring, the diagnostic challenge they provided, and the value of the information obtained using real-time three-dimensional echocardiography in such cases

Celestite upgrading by jigs in presence of steel balls as ragging material

Gravity separation using jigs is widely used for coarse particle sizes separation. However, fine sizes reduce jig performance. In this study, the upgrading of celestite ore by jig was investigated at different size fractions in the presence of ragging material. Three size fractions, i.e., -15+2 mm, - 2.0 + 0.50 mm and - 0.50 + 0.08 mm were used. The steel balls were used, as ragging material, to improve the separation of fines as well as to improve the concentrate quality. The statistical design was used to correlate celestite grade and recovery with studied operating variables, i.e., the ragging number of layers, ragging balls diameter, and separation time, at a fixed water flow rate and stroke length. The design results indicated that the ragging balls diameter and their number of layers play an important role. The smaller the ragging balls diameter and the higher the ragging number of layers are the better the concentrate grade but the longer the separation time. A celestite concentrate of (> 95% SrSO4) with 74.5% recovery was obtained for - 2.0 + 0.50 mm size fraction at the optimum conditions; i.e., 3.1 mm ragging balls diameter, one ragging layers, and 15 minutes separation time

Preferowany sposób czyszczenia węgla metodą flotacji: olej sosnowy czy MgCl.?

Coal flotation using inorganic salts receives special attention. It utilizes coal hydrophobicity to float coal without adding collectors. Although different salts were tested, chloride salts are the most promising ones. However, the stabilization of froth layer using the salts only is dubious. erefore, in this study, the flotation of coal was tested using either magnesium chloride or pine oil as a frother to see if there is a difference in coal flotation between these reagents in terms of ash removal and coal recovery in the float fraction. Additionally, both magnesium salt and pine oil were added together to clarify their interactive effect using statistical design. e results proved that the presence of either reagent (i.e., pine oil or MgCl.) is significant in reducing the ash content and increasing coal recovery. Using the MgCl. only reduced the ash to less than 4.3% with a coal recovery up to 28% while adding 1.0 kg/t pine oil along with 4 kg/t MgCl. enhanced the reduction of ash to less than 3% with a coal recovery of up to 80% at pH 2.Szczególną uwagę poświęca się flotacji węgla przy użyciu soli nieorganicznych. Wykorzystuje hydrofobowość węgla do flotacji węgla bez dodawania kolektorów. Chociaż testowano rożne sole, najbardziej obiecujące są sole chlorkowe. Jednak stabilizacja warstwy piany wyłącznie za pomocą soli jest wątpliwa. Dlatego w tym badaniu flotacja węgla była testowana przy użyciu chlorku magnezu lub oleju sosnowego jako spieniacza, aby sprawdzić, czy istnieje różnica we flotacji węgla między tymi odczynnikami pod względem usuwania popiołu i odzysku węgla we frakcji flotacyjnej. Dodatkowo dodano razem zarówno sol magnezową, jak i olejek sosnowy, aby wyjaśnić ich interaktywny efekt przy użyciu projektu statystycznego. Wyniki dowiodły, że obecność każdego z odczynników (tj. oleju sosnowego lub MgCl.) ma znaczący wpływ na zmniejszenie zawartości popiołu i zwiększenie odzysku węgla. Zastosowanie MgCl. tylko zmniejszyło popiół do mniej niż 4,3% z odzyskiem węgla do 28%, podczas gdy dodanie 1,0 kg/t oleju sosnowego wraz z 4 kg/t MgCl. zwiększyło redukcję popiołu do mniej niż 3% przy odzysku węgla do 80% przy pH 2