Rectus abdominis muscle flap (RAMF) technique for the management of bladder exstrophies: late clinical outcome and urodynamic findings

OBJECTIVE: To investigate the efficacy of the rectus abdominis muscle flap (RAMF) technique for the closure and augmentation of small, non-compliant bladder exstrophies. PATIENTS AND METHODS: The RAMF technique was used in two girls and two boys (mean age at operation, 31.7 months, range 3-72) with bladder exstrophy. The clinical outcome and urodynamics were assessed during a follow-up of 29 months to 6 years (mean 49.2 months) and included imaging, cystoscopy, biochemical and microbiological studies. RESULTS: There were no urinary tract infections, metabolic problems or electrolyte disturbances and kidney function remained normal in all patients. Radiography confirmed intact function and anatomy of the urinary tract and cystoscopy showed complete coverage of the inner peritoneal layer of RAMF with uroepithelium. No stone formation or mucus production were detected. Currently, three patients void using clean intermittent catheterization through the native urethra and the fourth through an appendiceal Mitrofanoff valve. However, the bladder volume was insufficient at the late follow-up and three patients required bladder augmentation. CONCLUSIONS: The RAMF technique is a good alternative for closing bladder exstrophies and achieves an increase in bladder capacity; however, although there is a mild improvement in bladder capacity and compliance. RAMF should not be used as a bladder augmentation procedure. The technique is indicated in the closure of large bladder defects, bladder exstrophies with small, inelastic, non-compliant bladder remnants and failed primary closures.     

Synthesis and characterization of poly(N‐vinyl‐2‐pyrrolidone) grafted sodium alginate hydrogel beads for the controlled release of indomethacin

Graft copolymers of sodium alginate (NaAlg) with N‐vinyl‐2‐pyrrolidone were prepared using azobisisobutyronitrile as initiator. The graft copolymers (NaAlg‐g‐PVP) were characterized with Fourier transform infrared spectroscopy, elemental analysis, and differential scanning calorimetry. Polymeric hydrogel beads of NaAlg and NaAlg‐g‐PVP were prepared by crosslinking method using glutaraldehyde (GA) as a crosslinker in the hydrochloric acid catalyst (HCl) and these beads were used to deliver anti‐inflammatory drug, indomethacin (IM). Chemical stability of the IM after encapsulation into beads was confirmed by FTIR. Preparation conditions of the NaAlg‐g‐PVP beads were optimized by considering the percentage entrapment efficiency, particle size, swelling capacity and their release data. In vitro release studies were performed in simulated gastric fluid (pH 1.2) for the initial 2 h, followed by simulated intestinal fluid (pH 7.4) for 4 h. Effects of GA concentration, exposure time to GA, drug/polymer (d/p) ratio, and concentration of HCl on the release of IM were discussed. It was observed that IM release from the beads decreased with increasing GA concentration and exposure time. IM release also decreases with increasing d/p ratio and HCl concentration. The highest IM release was obtained to be 77% for beads crosslinked with 0.027M GA. Swelling experiments were also performed to compute molecular mass between crosslinks of the beads. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of novel polyacrylate-clay sol-gel materials

Organo-functional silanes which were able to form chemical bonds with kaolinite and could also have an affinity to the materials of concern here, were studied by the sol-gel process. Polymethacrylate with trialkoxy silyl functional groups were prepared, hydrolysed and co-condensed with kaolinite. The progress of the hydrolysis, which proceeded very slowly, was followed by Karl-Fischer titration. Thermal behavior was investigated by differential thermal analysis. The extent of the reaction leading to network formation was qualitatively followed by Fourier transform-infrared spectroscopy and X-ray diffraction. Free-radical polymerization was carried out ultrasonically in the presence of a catalyst. Trimethoxy silane end-capped silane was found to be covalently bonded to kaolinite. The copolymers, with various amounts of kaolinite, were then hydrolysed and co-condensed in the presence of a catalyst to yield sol-gel materials which have a controllable combination of properties of both the polymer and kaolinite.     

Influence of Atomizing Gases on the Oxide-Film Morphology and Thickness of Aluminum Powders

Fine powders of aluminum were produced in a pilot-plant, inert-gas atomizerwith a confined-design nozzle, which operated vertically upward. Argonand helium at 1.85 MPa and nitrogen at 1.56 MPa were used as the atomizingagent. The morphology of the powder particles was examined by SEM. Powderswere sieved dry and wet. The Sauter mean diameter of the powders varied from20.70 to 10.25 m depending on the atomizing gas. The distribution ofsizes was bimodal. The mean thickness of oxide on the surface of the powderwas calculated from the total oxygen contents of powder samples (determinedby a Leco analyzer). In addition, ESCA measurements and BET tests werecarried out for surface-oxide thickness and area measurements,respectively. The finest powder produced under helium incorporated thinnersurface-oxide layers than the coarser ones produced under argon andnitrogen. This was due to differences in physical properties (such asdensity, thermal conductivity) and flow properties (such as gasvelocity and relative velocity) of the atomizing gases used, i.e., helium,argon, and nitrogen. The oxide was very irregular in thickness in thecoarse-size range of the Al powders produced under argon and nitrogen. Thiswas presumably because of the high- and low-temperature oxidation ofaluminum droplets during the atomization and subsequent solidification andcooling periods leading to the rough surfaces observed with SEMinvestigation in the present work.     

Evolutionary design of neural network architectures: a review of three decades of research

We present a comprehensive review of the evolutionary design of neural network architectures. This work is motivated by the fact that the success of an Artificial Neural Network (ANN) highly depends on its architecture and among many approaches Evolutionary Computation, which is a set of global-search methods inspired by biological evolution has been proved to be an efficient approach for optimizing neural network structures. Initial attempts for automating architecture design by applying evolutionary approaches start in the late 1980s and have attracted significant interest until today. In this context, we examined the historical progress and analyzed all relevant scientific papers with a special emphasis on how evolutionary computation techniques were adopted and various encoding strategies proposed. We summarized key aspects of methodology, discussed common challenges, and investigated the works in chronological order by dividing the entire timeframe into three periods. The first period covers early works focusing on the optimization of simple ANN architectures with a variety of solutions proposed on chromosome representation. In the second period, the rise of more powerful methods and hybrid approaches were surveyed. In parallel with the recent advances, the last period covers the Deep Learning Era, in which research direction is shifted towards configuring advanced models of deep neural networks. Finally, we propose open problems for future research in the field of neural architecture search and provide insights for fully automated machine learning. Our aim is to provide a complete reference of works in this subject and guide researchers towards promising directions.

     

Electrical and Dielectric Properties of Y<Superscript>3+</Superscript>-Substituted Barium Hexaferrites

In this study, Y³⁺ ion-substituted M-type barium hexaferrites (BaM; BaFe₁₂O₁₉) were fabricated via facile ceramic route. As-prepared powders were characterized by X-ray powder diffractometry (XRD), Fourier transform infrared (FT-IR) spectroscopy, and impedance spectroscopy. XRD (Rietveld) analyses confirmed the presence of a single characterization of all samples (except x = 0.0 and 0.1 samples). The crystallite sizes of products are found in the range of 47.2–63.2 nm. Spectral analysis (FT-IR) also presented the formation of spinel structure for all products. The ac conductivity of the substituted samples was found to initially decrease slightly with increase in Y³⁺ compared with unsubstituted, and then variation tendency changes at the medium substitution ranges are observed with a different attitude against temperature. In the end, the lower conductivity for high substitutions is recorded and increases as functions of frequency while it also increases with the elevation of temperature. It was observed that ac conductivities of products increased by increasing frequency which indicate that observed ac conductivity is due to both electronic and polaron hopping mechanism.     

An assessment of total RMR classification system using unified simulation model based on artificial neural networks

Engineering design has great importance in the cost and safety of engineering structures. Rock mass rating (RMR) system has become a reliable and widespread pre-design system for its ease of use and variety in engineering applications such as tunnels, foundations, and slopes. In RMR system, six parameters are employed in classifying a rock mass: uniaxial compressive strength of intact rock material (UCS), rock quality designation (RQD), spacing of discontinuities (SD), condition of discontinuities (CD), condition of groundwater (CG), and orientation of discontinuities (OD). The ratings of the first three parameters UCS, RQD, and SD are determined via graphic readings where the last three parameters CD, CG, and OD are estimated by the tables that are composed of interval valued linguistic expressions. Because of these linguistic expresions, the estimated rating values of the last three become fuzzy especially when the related conditions are close to border of any two classes. In such cases, these fuzzy situations could lead up incorrect rock class estimations. In this study, an empirical database based on the linguistic expressions for CD, CG, and OD is developed for training Artificial Neural Network (ANN) classifiers. The results obtained from graphical readings and ANN classifiers are unified in a simulation model (USM). The data obtained from five different tunnels, which were excavated for derivation purpose, are used to evaluate classification results of conventional method and proposed model. Finally, it is noted that more accurate and realistic ratings are reached by means of proposed model.     

Potensoft: MATLAB-based software for potential field data processing, modeling and mapping

An open-source software including an easy-to-use graphical user interface (GUI) has been developed for processing, modeling and mapping of gravity and magnetic data. The program, called Potensoft, is a set of functions written in MATLAB. The most common application of Potensoft is spatial and frequency domain filtering of gravity and magnetic data. The GUI helps the user easily change all the required parameters. One of the major advantages of the program is to display the input and processed maps in a preview window, thereby allowing the user to track the results during the ongoing process. Source codes can be modified depending on the users' goals. This paper discusses the main features of the program and its capabilities are demonstrated by means of illustrative examples. The main objective is to introduce and ensure usage of the developed package for academic, teaching and professional purposes.     

Biosorption of Acid Red P-2BX by lichens as low-cost biosorbents

The aim of this study is to examine the dye biosorption properties of lichen species called Cladonia convoluta and Evernia prunastri. Since lichens are extensively found in the environment, their suitability as a cheap adsorbent has been investigated in this study. The optimal parameters for textile dye biosorption were also determined. The dried lichen biomass showed better dye biosorption capacity than ash lichen biomass. C. convoluta had better dye biosorption capacity than E. prunastri. Dye biosorption rate was found as 71.41% at optimal conditions. This study concluded that C. convoluta was a successful and cheap biosorbent for treatment of water contaminated by Acid Red P-2BX dye.     

Combined Effects of Different Overload Ratios and Nitriding Process on Fatigue Crack Growth of AISI 4140 Steel

The combined effects of different overload ratios(OLRs)and nitriding process on fatigue crack growth(FCG)were analyzed.Steel compact tension specimens made of AISI 4140 steel were subjected to the plasma nitrification process using agas mixture of 50% N2 and 50% H2 at 500℃for 2h.Structural properties of the samples were studied by scanning electron microscopy,optical microscopy,microhardness testing and digital imaging.Plasma nitriding slowed down FCG,but the crack growth retardation caused by the overload was reduced when the OLR was 2.0and 2.5.Nitriding did not take effect when the OLR was 1.5and 3.0.