Avoidance of stomas and delayed anastomosis for bowel necrosis: the ''clip and drop-back'' technique

Necrotizing enterocolitis (NEC) and midgut volvulus (MGV) often are associated with extensive bowel necrosis. These cases may require extensive enterectomy and the formation of high or multiple stomas, and frequently are complicated by short bowel syndrome, excessive fluid losses, fistulas, stenosis, and skin breakdown. This report describes a "clip and drop-back" technique, followed by delayed anastomosis performed 48 to 72 hours later. The technique was successful in five severely ill infants (3 NEC, 2 MGV) with extensive necrosis, bowel perforation(s), and peritonitis, who required either a high stoma near the ligament of Treitz or multiple resections and enterostomies. This method removes obvious necrotic perforated bowel, controls contamination, avoids stomas (and their inherent complications in this age group), and preserves bowel length. All five babies survived. The technique is a useful addition to the pediatric surgeon's operative armamentarium in selective cases.     

Bootstrapping Boosted Random Ferns for discriminative and efficient object classification

In this paper we show that the performance of binary classifiers based on Boosted Random Ferns can be significantly improved by appropriately bootstrapping the training step. This results in a classifier which is both highly discriminative and computationally efficient and is particularly suitable when only small sets of training images are available.During the learning process, a small set of labeled images is used to train the boosting binary classifier. The classifier is then evaluated over the training set and warped versions of the classified and misclassified patches are progressively added into the positive and negative sample sets for a new re-training step. In this paper we thoroughly study the conditions under which this bootstrapping scheme improves the detection rates. In particular we assess the quality of detection both as a function of the number of bootstrapping iterations and the size of the training set. We compare our algorithm against state-of-the-art approaches for several databases including faces, cars, motorbikes and horses, and show remarkable improvements in detection rates with just a few bootstrapping steps.     

Morphology and mechanical properties of injection-molded specimens of two-phase polymer blends

An experimental study was carried out to investigate the moldability of polymer blends which form two phases in the molten state and the effect of mixing on the morphology and mechanical porperties of molded specimens. Blends of polystyrene with polypropylene and blends of polystyrene with high-density polyethylene were used for this study. A plunger-type injection molding machine (Van Dorn) was employed for molding specimens. To improve the mixing performance of the plunger machine, a Static Mixer (Kenics Corp., Super Nozzle) was installed between the heating cylinder and the sprue. A number of different molding conditions (injection pressure, temperature, injection time, cooling time) were varied, and molded specimens were collected under each molding condition. The specimens were used for studying the degree of dispersion in the blends and for determining the mechanical properties. A differential thermal analysis (DTA) experiment was also carried out to determine the degree of dispersion of the blends in molded specimens. It was found that a linear correlation exists between the blend composition and thermal spectra area of the blends tested.     

Fire-resistant cellulose boards from waste newspaper,boric acid salts,and protein binders

Clean Technologies and Environmental Policy - Housing construction consumes more materials than any other economic activity, with a total of 40.6 Gt/year. Boards are placed between...     

Studies on structural foam processing I. The rheology of foam extrusion

An experimental study was carried out to investigate the flow behavior of gas-charged molten polymers in foam extrusion. For the study, a rectangular slit die with glass windows was constructed to permit visual observations, from the direction perpendicular to flow, of the dynamic behavior of gas bubbles when a gas-charged molten polymer flows between two parallel planes. Pictures were taken of gas bubbles in the flow channel with the aid of a camera attached to a microscope, and these were later used to determine the position at which gas bubbles start to grow. Using three melt pressure transducers mounted on the short side of the rectangular slot, pressure distributions were measured along the longitudinal centerline of the die. The polymeric materials used were high-density polyethylene and polystyrene, and the chemical blowing agents used were a proprietary hydrazide which generates nitrogen, and sodium bicarbonate which generates carbon dioxide. It was observed that the gas-charged molten polymer shows a curved pressure profile as the melt approaches the die exit, whereas the polymer without a blowing agent shows a linear pressure profile. The visual observations of the bubble growth in the flow channel, together with the pressure measurements, permitted us to determine the bubble inflation pressure, often referred to as the critical pressure for bubble inflation. It was found that the critical pressure decreases with increasing melt extrusion temperature, and increases with increasing blowing agent concentration. It was also found that the bulk viscosity of gas-charged molten polymers decreases with increasing blowing agent concentration and with increasing melt temperature. A general remark is made concerning the precaution one should take when an Instron rheometer is used for determining the bulk viscosity of gas-charged molten polymers.     

Generation of smooth grids with line control for scattering from multiple obstacles

A new approach to generate structured grids for two-dimensional multiply connected regions with several holes is proposed. The bounding curves may include corners or cusps. The new algorithm constitutes an extension of the Branch Cut Grid Line Control (BCGC) technique introduced byVillamizar et al. [V. Villamizar, O. Rojas, J. Mabey, Generation of curvilinear coordinates on multiply connected regions with boundary-singularities, J. Comput. Phys. 223 (2007) 571–588] to domains with a finite number of holes. Regions with multiple holes are reduced to several contiguous single hole subregions. Then, the BCGC algorithm is applied to each single hole subregion producing a smooth grid with line control. Finally, the subregions with their respective grids are joined and their interfaces are smoothed resulting a globally smooth grid. The advantages of the novel grids are revealed by employing them to numerically solve acoustic scattering problems in the presence of multiple complexly shaped obstacles.     

Alternative for the Treatment of Leachates Generated in a Landfill of Norte de Santander–Colombia,by Means of the Coupling of a Photocatalytic and Biological Aerobic Process

In the present study, the use of heterogeneous photocatalysis TiO2/UV coupled to an activated sludge reactor was evaluated as an alternative treatment for the leachate coming from a Landfill, located in Cucuta (Colombia). TiO₂ (Degussa P-25) between 100 and 600 mg.L^?1 was used as a catalyst, semi-continuous type reactors for the photocatalysis, a batch for the biological stage, UV light with accumulated energies from 20 to 60 kJ.L^?1 were also used, a constant concentration of H₂O₂ was used as an adjuvant in all tests. The research consisted of four main phases: leachate characterization, biological treatment, optimization of photocatalytic and AOP-biological coupling. For the optimization of the photocatalytic step, an experimental design was carried out through the statistical program Statgraphics Centurion XV of factorial type 3^2 (3 levels 2 variables), modeling the results by means of a response surface, the variables of the pH and the concentration of the catalyst were included, having this as input for the response of interest the percentage (%) of DOC removal. The biological process itself provided a removal of 38 and 24% for COD and DOC, respectively. The AOP-biological coupling provided a removal of 68 and 76% in terms of COD and DOC, respectively. Thus, the coupling significantly improves the overall efficiency of the process by more than 50%, which represents a promising improvement compared to the removal of organic matter for the treatment of the same type of water using only the biological process. The results show a viable alternative for the treatment of leachate because higher removal levels are achieved in residence times, which are considered shorter than the ones in conventional processes.

     

An EIS study of the effect of the pedant group in imidazolines as corrosion inhibitors for carbon steel in CO2 environments

Electrochemical impedance spectroscopy (EIS) measurements were carried out to study the corrosion inhibition of carbon steel in 3 % NaCl with and without diesel saturated with CO₂ at 50 °C. The inhibitors examined were hydroxyethyl (HEI‐18), amino ethyl (AEI‐18), and amide ethyl imidazolines (AMEI‐18). When the oily phase, i.e diesel, is absent, the inhibition efficiency of the imidazolines is low, around 80 %. It was found, however, that the inhibition dramatically increased with the presence of the oily phase, because the imidazolines are able to act as both emulsifiers and corrosion inhibitors. Experimental results showed an increase in the film resistance (R_f), charge transfer resistance (R_ct), capacitance of the film and the capacitance of the double layer values with the addition of inhibitor in presence of the oily phase also in several orders of magnitude. The most effective inhibitor in presence of diesel is a solution of AMEI‐18, as the oily phase is carried to the surface also. This is due to the presence of two large alkyl groups than the only chain present in the HEI‐18 and AEI‐18 imidazolines with better hydrophobic properties associated with the formation of a protective film that reduces drastically the corrosion process. The effects of the interaction of inhibitors with hydrocarbons and the correlation on the performance of inhibitor films have been examined.     

The role of coupling agents on the mechanical properties of polymer-impregnated mortars

An investigation has been carried out for determining the effect of coupling agents on the mechanical properties of polymer-impregnated mortars. Mortar specimens were impregnated with methyl methacrylate (MMA) monomer and α, α-azobis-isobutyronitrile initiator, and polymerized thermally in water. Three titanate coupling agents, KR-33CS, KR-55, and KR-138s, and one silane coupling agent, the A-174, were used for the investigation. Varying amounts of coupling agent were used in impregnating the mortars in situ or in pretreating the mortars with a solvent system. Bulk polymerization of MMA shows no appreciable influence of the coupling agents in the reaction kinetics; however, with the exception of KR-138S, all polymers obtained in the presence of coupling agents came out as insolble. Similar results were obtained for polymers extracted with acetone from mortars. The mechanical property results show an improvement of properties in mortars containing 5.0 vol% of KR-33CS and A-174 after impregnation in situ. A slightly better improvements of mechanical properties were obtained by pretreating the mortar specimens with acetone or toluene/xylene containing coupling agents. Microscopic observation of the fracture surface showed no noticeable difference in the surfaces prepared with and without coupling agents.     

Development of stress birefringence and flow patterns during mold fillin and cooling

An experimental study was carried out to investigate the development of stress birefringence patterns of molten polymer during the mold filling and cooling operation. For this study, a rectangular mold cavity with glass windows on both sides was constructed, which permitted us to record on a movie film the changes in stress birefringence patterns in the mold cavity during the molding operation, using a circular polariscope. The mold was equipped with an automatic relay system which closes the shut-off valve when the pressure in the mold cavity reaches a predetermined value. The mold was also equipped with both heating and cooling devices, so that either isothermal or non-isothermal injection molding could be carried out. The mold temperature was controlled by thermistor regulated controllers. During the entire cycle of the molding operation, the mold cavity pressure was continuously recorded on a chart recorder, using a melt pressure transducer. The present study shows how molding conditions (namely, injection pressure, melt temperature, mold temperature) influence the distribution of stress birefringence patterns in a molten polymer while it is being injected into, and cooled in, a rectangular mold cavity.