Partial left ventriculectomy for idiopathic dilated cardiomyopathy: early results and six-month follow-up

BACKGROUND: Recent reports show that partial left ventriculectomy improves hemodynamic and functional status in patients with dilated cardiomyopathy. This study sought to determine the effects of partial left ventriculectomy on clinical outcome and left ventricular function during 6-month follow-up. METHODS: Twenty-two patients underwent partial left ventriculectomy. Mitral valve repair was performed whenever possible, otherwise the valve was replaced. Hemodynamic and functional data were obtained at baseline, as well as 2 weeks and 6 months postoperatively. RESULTS: Overall, 7 of 22 patients died; there were three early and four late deaths. One-year survival was 68%+/-10%. Ejection fraction increased from 23.9%+/-6.8% before the operation to 40.7%+/-12.5% at 2 weeks and to 36.8%+/-7.7% at 6 months (p<0.001, for both). The cardiac index before the operation, at 2 weeks, and at 6 months was 2.3+/-0.8, 2.9+/-0.6, and 3.4+/-1.0 L/m2 per minute, respectively (p = 0.035, and p = 0.009, compared with baseline). The increase in ejection fraction 2 weeks postoperatively was less in patients with left circumflex artery dominance (10.9%+/-3.2% compared with 19.9%+/-10.7%, respectively, p = 0.017). At 6-month follow up, all surviving patients except one improved New York Heart Association functional class when compared with preoperative status (from 3.8+/-0.4 to 1.4+/-0.6, p = 0.0002). CONCLUSIONS: Early hemodynamic improvement after partial left ventriculectomy was maintained during midterm follow-up.     

Peculiarities of myocardial infarction at young age in Southern Croatia

The aim of this study was to assess whether acute myocardial infarction (AMI) in younger patients (< 45 years) differs from that in the older individuals (> 45 years). We have studied the records of all patients admitted to the Department of Medicine, Clinical Hospital of Split, Croatia, because of AMI from January 1st, 1987 to December 31st, 1991. The study group consisted of 1406 patients, 130 (9.2%) below, and 1276 (90.8%) above the age of 45. In the ?young? subgroup there were only 9 females (6.9%), significantly less than in the ?old? one (399 out of 1276 or 31.3%, p < 0.001). There were many more smokers among the younger (100 out of 130 or 76.9%) than among the older patients (524 out of 1276 or 41.1%, p < 0.001). The location of myocardial necrosis was also different: inferior infarction occurred in 65 out of 130 or 50% young patients and in 442 out of 1276 or 34.6% old patients; p < 0.001). Finally, the hospital mortality rate among the younger AMI patients was quite low (8 out of 130 or 6.2%) when compared to that of the older patients (282 out of 1276 or 22.1%, p < 0.001). In conclusion, AMI in younger individuals shows relevant peculiarities: the background of such patients almost invariably includes cigarette smoking; the female gender is about five times less affected, the diaphragmatic location is nearly two times more frequent, and the hospital mortality rate of these patients is almost four times lower than that of older patients.     

Static Stability of Liquid Bridges Between Matrix Blocks of a Gas Invaded Zone of Naturally Fractured Reservoirs

A large portion of oil and gas reservoirs in the world are located in naturally fractured reservoirs. Despite such importunity, the production mechanisms of these reservoirs are not completely well defined. Gas–oil gravity drainage that takes place in the gas-invaded zone of this type of reservoirs is one instance of such a weakness. The density difference between gas-filled fractures in contact with oil-saturated matrix blocks brings the oil out of the matrix blocks into the fracture. The drained oil can reach the production well through two different paths: continues fracture network and block-to-block path. These two different paths require different approaches to modeling of gravity drainage. Single-block approaches are used when drained oil only travels through the fracture network, which totally formulated before. But when oil prefers to travel through the matrix blocks, continuum approaches such as Darcy's law may not work in their basic forms any more. Liquid bridges and film that form in the horizontal fracture between matrix blocks usually transfer the wetting phase across the fracture. Stability condition and duration of stability can help better understanding of gravity drainage in stacks of blocks. In this article, the stability of liquid bridges between the matrix blocks studied and a minimum length of stability is predicated. The results show that this stable length of liquid bridges formed between adjacent matrix blocks is 2r₀π, which is a function of the pore throat. This critical length can be used in modeling of capillary continuity and wetting phase transfer across matrix blocks.     

Trajectory planning for multiple unmanned vehicles under reciprocal constraints

In this article, a special class of trajectory optimization problems is formalized and solved. It involves the optimization of different unmanned vehicle (UMV) trajectories that are coupled through reciprocal constraints. It is shown in the article that searching for a solution to the problem at hand may stipulate not just planning a longer than the shortest possible path for each UMV, but also choosing slower travel speeds in order to co-ordinate between the UMVs. Although it seems that solving the problem possesses merits, it has been only partially treated before. Here it is solved by utilizing an evolutionary approach which involves a new algorithmic feature that allows striving towards the desired optimality. The approach is demonstrated and studied through solving and simulating several trajectory planning problems. It is shown that a wide range of problems might be related to that class of problems.     

Effect of different forms of anionic nanoclays on cytotoxicity

Anionic nanoclays, so-called layered double hydroxide (LDH) nanoparticles, have been extensively applied as drug delivery systems, since they efficiently enter cells via endocytosis pathway and possess controlled release property. However, the stability of LDHs varies, depending on the type of interlayer anions, which can also affect their toxicity. In this study, we investigated the effects of two different forms of LDH, carbonate form (MgAl-LDH-CO3) and chloride form (MgAl-LDH-Cl), on cytotoxicity in human lung epithelial cells. The result showed that MgAl-LDH-Cl was more easily dissolved into metal ions under simulated lysosomal (pH 4.5) and body fluid (pH 7.4) conditions than did MgAl-LDH-CO3. According to cytotoxicity evaluation, MgAl-LDH-CO3 exhibited high toxicity compared with MgAl-LDH-Cl in terms of induction of oxidative stress, apoptosis and membrane damage. These results suggest that easily dissoluble MgAl-LDH-Cl has low cytotoxicity, while high stability of MgAl-LDH-CO3 is correlated to elevated cytotoxicity.     

Out-of-plane stresses in composite shell panels: layerwise and elasticity solutions

Boundary-layer effects in lengthy cross-ply laminated circular cylindrical shell panels under uniform axial extension are investigated by two analytical solutions. First, Reddy??s layerwise theory with state-space approach is utilized to determine the local interlaminar stresses. In this method, the general displacement field is discretized through the shell thickness by a linear shape function. When the shell panel is subjected to an axial force, the axial strain is estimated by an equivalent single-layer theory. Second, the stress-function approach along with Fourier series expansion is applied to develop a novel elasticity solution. The elasticity solution, which is based on simply-support edge conditions, is presented to show the effectiveness of the first solution. The numerical results show good agreements. Interlaminar stresses within various symmetric and unsymmetric cross-ply composite shell panels are then calculated and discussed. It is shown that the normal out-of-plane stress can get high magnitudes along the physical interfaces.     

A Novel Technique for Ice Crystal Visualization in Frozen Solids Using X-Ray Micro-Computed Tomography

A novel technique, using an X‐ray micro‐computed tomography system (X‐ray micro‐CT system) has been developed for visualization of the two‐ (2‐D) and three‐dimensional (3‐D) ice crystal structures formed during freezing. The system reconstructs all 3‐D images based on a set of 2‐D images obtained by multiple slicing of an X‐ray shadow image. This study demonstrates the capability of the technique to characterize the ice crystal microstructure of mycoprotein products after freezing. Results are presented for the 2‐D ice crystals formed within mycoprotein frozen at different rates. The method requires freeze‐drying of the sample to remove frozen water before scanning to indicate ice crystal and internal structure of the material at a depth of 1 cm. The dendrite spacing of ice crystals has been related to the freezing conditions of the material.     

Evaluation of specific absorbed fractions from internal photon sources in ORNL analytical adult phantom

To design a diagnostic or therapeutic irradiation programme, there is a need to estimate the absorbed dose. In this investigation, specific absorbed fractions (SAFs) were calculated based on Cristy and Eckerman's analytical adult phantom, by MCNP4C Monte Carlo code. SAFs were estimated with uncertainty <3%, for about 600 source organ-target organ pairs at 12 photon energies (these data are available at http://www.um.ac.ir/~mirihakim). Then these results were compared with Cristy and Eckerman's, which were based on direct Monte Carlo, reciprocity principle and point source kernel methods. Also, agreements and disagreements between them for different states were discussed.     

An investigation on effect of geometrical parameters on spray cone angle and droplet size distribution of a two-fluid atomizer

A visual study is conducted to determine the effect of geometrical parameters of a two-fluid atomizer on its spray cone angle. The liquid (water) jets exit from six peripheral inclined orifices and are introduced to a high speed gas (air) stream in the gravitational direction. Using a high speed imaging system, the spray cone angle has been determined in constant operational conditions, i.e., Reynolds and Weber numbers for different nozzle geometries. Also, the droplet sizes (Sauter mean diameter) and their distributions have been determined using Malvern Master Sizer x. The investigated geometrical parameters are the liquid jet diameter, liquid port angle and the length of the gas-liquid mixing chamber. The results show that among these parameters, the liquid jet diameter has a significant effect on spray cone angle. In addition, an empirical correlation has been obtained to predict the spray cone angle of the present two-fluid atomizer in terms of nozzle geometries.