Exploring urban students’ constructions about school, work, race, and ethnicity.

This qualitative study is an exploration of 32 urban high school students’ narratives about the connection between school, work, and societal expectations of their future success related to their racial and ethnic background. The sample varied along 2 contextual dimensions: participation in a psychoeducational intervention (Tools for Tomorrow) and developmental status (i.e., half the sample were 9th-grade students and the other half were 12th-grade students). Using consensual qualitative research, the narratives revealed 3 major domains: future orientation; students’ perceptions of society’s expectations based on race and ethnicity; and students’ perception of the role of their race and ethnicity in future success. Results reveal that the majority of students endorse a connection between school and work, believe that society holds low expectations for them based on their racial and ethnic background, and cannot predict their future success based on their background. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mercury and lead sorption properties of poly(ethyleneimine) coated onto silica gel

In this article, we studied the sorption properties of poly(ethyleneimine) coated on silica gel for metal ions with impact on the environment, such as Zn(II), Cd(II), Hg(II), and Pb(II). The experiments were carried out by batch procedure and the effects of pH, concentration, and temperature were evaluated. In addition, the selectivity was studied for binary, ternary, and quaternary metal ion mixtures. Mercury and lead showed promising results, achieving higher than 65% of sorption after only 1 h of contact. Under competitive conditions, resin presented high selectivity toward Hg(II) reaching 91 and 87% of retention respect to total amount of ions for binary and quaternary mixtures, respectively. The effect of time on Pb(II) and Hg(II) sorption was studied by batch procedure and the experimental data were adjusted to pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. Pseudo-second-order model presented good agreement for Pb(II) sorption, while pseudo-first-order model fits better to Hg(II) sorption. Intra-particle diffusion model showed that sorption process is controlled mainly by film diffusion.     

In vitro determination of digestible and unavailable protein in edible seaweeds

Edible seaweeds are considered a complementary source of food protein for human and animal nutrition. The physiological effects of seaweed protein depend on the degree of enzymatic digestion of protein in the small intestine and bacterial fermentation in the large intestine. The objective of this work was to estimate total, digestible, fermentable and unavailable protein in some red and brown seaweeds. Brown seaweeds Fucus vesiculosus, Laminaria digitata and Undaria pinnatifida and red seaweeds Chondrus crispus and Porphyra tenera were treated with pepsin and pancreatin to separate digestible protein. Residues containing indigestible protein were inoculated for 24 h with rat caecal droppings, and protein contents were evaluated in the non‐fermented residue. Protein content in the seaweeds ranged from 8.9 to 25% of dry matter. Digestible protein was the major protein fraction (69%) only in P tenera; in the other seaweeds, this fraction ranged from 15 to 45%. Significant amounts of unavailable protein were found in all samples (2–24%). The distribution of total protein among the three fractions, ie digestible, fermentable and unavailable protein, could yield information about the physiological and metabolic consequences of the intake of seaweed proteins. © 2002 Society of Chemical Industry     

Synthesis, characterization, and sorption properties of water-insoluble poly(2-acrylamido-2-methyl-1-propane sulfonic acid)–montmorillonite composite

The sorption properties of composites based on 2-acrylamido-2-methyl-1-propane sulfonic acid and montmorillonite are presented. Gel-type composites were obtained via in situ polymerization. Resin particles presented exfoliated morphologies, as suggested by X-ray diffraction. The addition of montmorillonite resulted in enhanced mechanical properties, as evaluated by Vickers microhardness tests. The swelling performances of the resins exhibited a fast initial water uptake, reaching the maximum absorption capacity after less of 1 h of contact. A batch procedure was used to evaluate the sorption characteristics of the composites, and the effects of pH, montmorillonite content, and time were studied. The composites showed high adsorption capacities at pH values of 3.0 and 5.0, and the addition of montmorillonite did not result in a significant enhancement of their adsorption capacity. The equilibrium adsorption performance can be described by the Langmuir isotherm, while kinetic experiments revealed an excellent agreement with the pseudo-second-order model.     

Catalytic use of zeolites in the Prins reaction of arylalkenes

The Prins reaction of various arylalkenes with paraformaldehyde on different zeolites as solid acid catalysts was studied. The main product of the reaction under the experimental conditions used was found to be the corresponding 1,3-dioxane. Of the catalysts tested, beta (75) zeolite proved the most active and selective in the Prins reaction of styrene, with a selectivity of 41.4% and a conversion of 95%. Other zeolites such as USY and, especially, ZSM-5, provided much lower yields. The reactions of other arylalkenes were found to be strongly influenced by the substituents on the double bond.     

Polymer supports for the removal and degradation of hazardous organic pollutants: an overview

Over the last decades, the presence of highly organic pollutants has increased and become an environmental problem that affects all forms of life. To solve or reduce this problem, multiple strategies have been proposed for the elimination and degradation of organic compounds in aqueous media. This review aims to revise and critically discuss the most recent advances in polymer supports to be used for the adsorption and degradation of organic pollutants. However, the greatest challenge with respect to this issue is the industrial scale‐up of bioremediation processes that allow the removal and degradation of compounds in a continuous and large‐scale manner. © 2019 Society of Chemical Industry     

Multipath interconnection: a technique for reducing congestionwithin fast packet switching fabrics

The banyan interconnection is prone to internal link congestion, resulting in a blocking switch architecture. Several solutions that have been implemented to reduce the severity of link congestion offer packets a multiplicity of paths, which tend to increase packet delay variability and allow delivery of out-of-sequence packets. This, in turn, can lead to an increase in end-to-end protocol complexity, particularly in the case of real-time services. A solution called multipath interconnection is proposed to overcome this difficulty. Multiple (i.e., alternate) paths are provided and one is selected at call-setup time. Subsequent packets belonging to the call are constrained to follow the selected path. A number of path selection strategies are presented     

Influence of hydrocortisone acetate on the magnesium metabolism during pregnancy in rats

The influence of hydrocortisone acetate i.m. administered (4 mg/100 g of body weight and day) to pregnant rats, on magnesium nutritive utilization and bone magnesium content in the mothers and its possible repercussions on newborn Mg content are studied. Hydrocortisone acetate treatment significantly reduces Mg content in the litters, which can be explained on the basis of a significant decrease in both the magnesium absorption and retention by the hormone-treated mothers. The mobilization of femoral magnesium and the increase in the urinary excretion of the cation provoke a reduction in magnesium retention in the treated mothers.     

Alternative laparoscopic management of perforated peptic ulcers

Surgery--namely, suture closure-is still the treatment of choice for perforated peptic ulcers, despite the proven efficacy of Taylor's conservative approach. Such conservative management, however, has been proven less effective in high-risk patients and those with perforations more than 12 h old. Here we suggest alternative laparoscopic treatments for perforated peptic ulcers. We have treated laparoscopically six patients (one F, five M; mean age 57.6 years; range 31-81 years); the mean duration of the operation was 52 min; the median hospital stay was 7 days (6-15 days); H2-blockers, antibiotics, and fluids were administered in the p.o. course; the follow-ups range from 6 to 18 months. On the basis of our experience, the treatment of choice for perforated peptic ulcers is Taylor's conservative procedure and laparoscopic drainage of the abdominal cavity when there is mild peritoneal reaction (usually less than 6 h from the onset of perforation). In case of remarkable peritonitis (usually more than 12 h), it is mandatory to add an accurate lavage. When the site of perforation is concealed by the peritoneal inflammation it should not be searched; when visible, it might be obliterated with the round ligament or an omental tissue strand, particularly if larger than 1 cm in diameter.     

A Wheelchair Steered through Voice Commands and Assisted by a Reactive Fuzzy-Logic Controller

This paper describes new results with a Reactive Shared-Control system that enables a semi-autonomous navigation of a wheelchair in unknown and dynamic environments. The purpose of the reactive shared controller is to assist wheelchair users providing an easier and safer navigation. It is designed as a fuzzy-logic controller and follows a behaviour-based architecture. The implemented behaviours are three: intelligent obstacle avoidance, collision detection and contour following. Intelligent obstacle avoidance blends user commands, from voice or joystick, with an obstacle avoidance behaviour. Therefore, the user and the vehicle share the control of the wheelchair. The reactive shared control was tested on the RobChair powered wheelchair prototype [6] equipped with a set of ranging sensors. Experimental results are presented demonstrating the effectiveness of the controller.