Structure and catalytic activity of highly ordered AlMCM-48 materials with different Si/Al ratios on the degradation of high-density polyethylene

Journal of Porous Materials - Catalysts of AlMCM-48 with different Si/Al molar rations were synthesized by modified hydrothermal method with respect to previous works. As a consequence, the...     

Immunohistochemistry of neuronal nitric oxide synthase and protein nitration in the striatum of the aged rat

To ascertain the possible implications of the nitric oxide (NO*) producing system in striatal senescence, and by using immunohistochemistry and image-processing approaches, we describe the presence of the enzyme nitric oxide synthase (NOS), the NADPH-diaphorase (NADPH-d) histochemical marker, and nitrotyrosine-derived complexes (N-Tyr) in the striatum of adult and aged rats. The results showed neuronal NOS immunoreactive (nNOS-IR) aspiny medium-sized neurons and nervous fibres in both age groups, with no variation in the percentage of immunoreactive area but a significant decrease in the intensity and in the number of somata with age, which were not related to the observed increase with age of the striatal bundles of the white matter. In addition, NADPH-d activity was detected in neurons with morphology similar to that of the nNOS-IR cells; a decrease in the percentage of area per field and in the number of cells, but an increase in the intensity of staining for the NADPH-d histochemical marker, were detected with age. The number of neuronal NADPH-d somata was higher than for the nNOS-IR ones in both age groups. Moreover, N-Tyr-IR complexes were observed in cells (neurons and glia) and fibres, with a significant increase in the percentage of the area of immunoreaction, related to the increase of white matter, but a decrease in intensity for the aged group. On the other hand, we did not detect the inducible isoform (iNOS) either in adult or in aged rats. Taken together, these results support the contention that NADPH-d staining is not such an unambiguous marker for nNOS, and that increased protein nitration may participate in striatal aging.     

Legumes seeds protein isolates in the production of ascorbic acid microparticles

This study evaluated the use of pea (Pisum sativum) and cowpea (Vigna unguiculata) protein isolates (PPI and CPI) in the microencapsulation of ascorbic acid (AA), by spray drying. PPI and CPI were used pure or mixed with maltodextrin (M) as wall materials of AA. The process yield was improved from 66% to 86% by the addition of M (CPI/M and PPI/M); also, AA particles yield was 79%. The AA retention from the drying process was higher in PPI/M (69%) than in CPI/M (66%), and this was attributed to PPI proteolysis profile, demonstrated by the SDS–PAGE electrophoresis. Scanning electron microscopy revealed that AA particles were similarly spherical and shriveled. Mean particle sizes of PPI/M/AA and CPI/M/AA were 7 and 8 μm, respectively. This study showed the exploration of protein isolates from legumes in the development of a microparticulate system containing AA with great potential for use in human health.     

Fixation of Chromium in Wood from Dichromate and Chromate Salt Solutions

It has been reported that treatment of wood surfaces with aqueous solutions of chromium trioxide imparts some beneficial properties like weather resistance and some degree of water repellency. The work presented here aims at finding alternative ways of fixing chromium in wood with the avoidance of the very acidic and strong oxidant conditions of chromic acid solutions. This is because these solutions may affect the strength of wood, and are known to have a very high human toxicity. In this study, chromium has been fixed into wood from hexavalent chromium solutions at pH's of ～1.5 (CrO₃ aq.), ～3.8–3.9 (K₂Cr₂O₇ aq.) and ～9.5–10.3 (K₂CrO₄ aq.). For the CrO₃-solutions the effects of temperature and reaction time on the fixation of chromium were investigated. For the dichromate and chromate solutions, fixation experiments were carried out with Cr-concentration and reaction times as variables. It is shown that a 3%-fixation level of chromium in small wood specimens can be attained from dichromate and chromate solutions without significant mechanical damage to wood. On the other hand, even diluted CrO₃-solutions (0.01 M) impart serious strength reductions in wood at temperatures of 90° C and higher when reacted for 8 hours, and the chromium content of wood resulting from such treatment is of the order of only 1%.     

Predominance and characteristics of Burkitt lymphoma among children with non-Hodgkin lymphoma in northeastern Brazil

The purpose of this paper was to define the histologic distribution, clinical features, and treatment response of childhood non-Hodgkin lymphoma (NHL) in northeastern Brazil. We reviewed medical records and histopathologic studies of 98 children treated for NHL from 1980 to 1987 at a major pediatric cancer center in Recife, Brazil. Treatment outcome was evaluated in relation to tumor burden (stage and serum LDH) and type of therapy (LSA2L2 vs other multiagent chemotherapy). There was a striking predominance of the small noncleaved cell (Burkitt) subtype, which occurred in 92 of the 98 children and adolescents diagnosed with NHL. Subsequent analyses focused on these patients. The majority (n = 84) had advanced (stage III/IV) disease at diagnosis. The abdomen was the most common site of disease (84 cases); jaw involvement was rare (three cases). Five-year event-free survival (excluding treatment refusals) was significantly better for patients with limited vs advanced stage disease (75 +/- 14% vs 42 +/- 6%; P < 0.04). Elevated serum LDH (>500 U/l) was associated with a poorer outcome (P = 0.008). The type of chemotherapy did not affect EFS (P = 0.95). Only 39% of patients are long-term survivors, reflecting the high rate of septic deaths (25% of patients) and parental refusal/abandonment of therapy (10%). Epstein-Barr virus (EBV) was detected in tumor cells from eight of the 11 cases studied. In clinical presentation, these cases resemble sporadic Burkitt lymphoma, yet in their apparent responsiveness to LSA2L2 therapy and association with EBV, they do not. Childhood NHL in northeastern Brazil is predominantly of the Burkitt subtype, and is associated with clinical features that appear to distinguish it from the endemic and sporadic forms of this tumor. These cases may represent a third or intermediate subtype of Burkitt lymphoma.     

Optimization of mixed Langmuir-Blodgett films of a water insoluble porphyrin in a calixarene matrix for optical gas sensing

The gas sensing capabilities of Langmuir-Blodgett (LB) mixed films of 5,10,15,20-tetrakis[3,4-bis(2-ethylhexyloxy)phenyl]-21H,23H-porphine (EHO) and p-tert-butylcalix[8]arene (C8A) have been studied in this work. Although EHO is known to be very sensitive to NO₂ gas, this study demonstrates that the C8A matrix improves the sensing properties of the porphyrin molecules in the solid state. After the exposure to NO₂ and the subsequent recovery, the UV-vis spectrum of a C8A:EHO film shows no aggregation of the porphyrin. In atomic force microscopy (AFM) images, C8A:EHO films appear with sharper surfaces than those made of pure EHO, allowing a better accessibility of the gas molecules to the active binding sites. Multilayer LB films of the C8A:EHO system ranging from 2 to 40 layers have been prepared to study their response to NO₂ by UV-vis spectroscopy, and their kinetics reveal an important thickness dependence. Through the analysis of AFM images, it has been found that the surface roughness increases until the sample reaches 20 layers and then remains almost constant, which is related to the response time. The optimum film thickness has been found to be 20 layers, for which both the speed of response and the surface roughness are maximum.