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I Lopes

Publications and source records attributed to I Lopes.

13 recordsLinked to original sources
PubMed2004

Neutron capture cross section measurement of 151Sm at the CERN neutron time of flight facility (n_TOF).

The151Sm(n,gamma)152Sm cross section has been measured at the spallation neutron facility n_TOF at CERN in the energy range from 1 eV to 1 MeV. The new facility combines excellent resolution in neutron time-of-flight, low repetition rates, and an unsurpassed instantaneous luminosity, resulting in rather favorable signal/background ratios. The 151Sm cross section is of importance for characterizing neutron capture nucleosynthesis in asymptotic giant branch stars. At a thermal energy of kT=30 keV the Maxwellian averaged cross section of this unstable isotope (t(1/2)=93 yr) was determined to be 3100+/-160 mb, significantly larger than theoretical predictions.

Journal Article↗
PubMed2004

Genetic determination of tolerance to lethal and sublethal copper concentrations in field populations of Daphnia longispina.

In order to study the effects of environmental pollution on the genetic diversity of natural populations, two field populations of the cladoceran Daphnia longispina were sampled: one in a reference site (uncontaminated) and the other in a site historically stressed with acid mine drainage (AMD). Five hypotheses were formulated: (1) the stressed population presents a higher tolerance to lethal levels of copper than the reference population, (2) differences in tolerance to lethal levels, observed between the two populations, are due to the loss of sensitive lineages, (3) differences in tolerance to lethal levels of copper between the two populations are due to the appearance of new genotypes, (4) the acquisition of tolerance to lethal levels of copper involved changes in life-history patterns and fitness costs under optimal conditions, and (5) historical contamination by AMD resulted in tolerance differences to sublethal levels between populations, within categories similarly tolerant to lethality, specifically, lineages with similar tolerance to lethal levels from both populations show differences in tolerance to sublethal levels, the stressed population being more tolerant to sublethal levels of contamination than the reference population. Over 125 acclimated cloned lineages, from each population, were exposed to different copper concentrations for 24 hours. At the end of each assay, mortality and feeding inhibition were monitored. Life-cycle traits under optimal conditions were also monitored (time to first brood, number of neonates per brood, inter-brood time, body length, and ingested algae). At lethal levels of copper, significant differences were found in the frequency of sensitive lineages between the two populations. The stressed population did not include the most sensitive lineages, though the most tolerant ones were also present in the reference population. Thus, the hypothesis of presence of new genotypes in the stressed population resulting in an overall increase tolerance of the population at lethal levels was rejected. Changes in life-history patterns were detected, though they were not fully consistent with predictions of life-history theory. Furthermore, these changes in life-history patterns did not involve fitness costs. The fifth hypothesis was rejected since, at sublethal levels of copper, no significant differences were found between the feeding inhibitions of similarly lethal tolerant lineages of the two populations, with only one exception. Therefore, the present study further confirmed the genetic erosion hypothesis and gave further support to the incorporation of genetic diversity measurements into risk assessments.

Animals↗
PubMed2003

Monitoring cell detachment by surfactants in a parallel plate flow chamber.

The efficacy of the surfactants SDS and CTAB in detaching P. fluorescens from glass surface was evaluated in a parallel plate flow chamber. This device enables "in situ" determinations of cells detachment following the application of surfactants under well controlled hydrodynamic conditions. The results showed that SDS was able to remove almost all adhering bacteria in a short period of time, whereas CTAB did not promote much cell desorption. On the contrary, this surfactant increased the adhesion strength between cells and glass. Both surfactants promoted different alterations of cell surface properties, which explain their dissimilar effectiveness as cleansing agents.

Absorption↗
PubMed2002

Prolidase deficiency with hyperimmunoglobulin E: a case report.

Prolidase deficiency is a rare, inherited disorder characterized by ulceration of the skin, mental retardation, and massive urinary excretion of imidodipeptides. Most patients also have recurrent infections, an unusual facial appearance, and splenomegaly. We describe a girl presenting with chronic dermatitis, recurrent respiratory tract infections since her first months of life, and facial features characteristic of prolidase deficiency. The diagnosis of prolidase deficiency was made at 4.5 months of age. The immunologic study in this patient showed an extreme and progressive increase of total immunoglobulin E (IgE) in serum (reaching the value of 77,600 IU/l) and defective chemotactic function of the neutrophils. Treatment with a hyper-proteic diet supplemented with ascorbic acid, manganese chlorite, and topical proline resulted in reduction of the frequency and severity of the infections and significant improvement of the skin lesions. The authors discuss the immunologic alterations and the favorable evolution with treatment in this patient.

Amino Acid Metabolism, Inborn Errors↗
PubMed2001

Solid-state structure and solution behavior of eight-coordinate Sm(III) poly(pyrazolyl)borate compounds.

[Sm(Tp(Me2)(2)(kappa(2)-S(2)CNR(2))] compounds (R = Et (1), Me (2); Tp(Me2) = HB(3,5-Me2pz)(3)) have been isolated from reaction of (R(2)NC(S)S)(2) with 2 equiv of [Sm(Tp(Me2)(2)]. Reductive cleavage of 2,2'-dipyridyl disulfide or 2,2'-dipyridyl diselenide by [Sm(Tp(Me2)(2)] afforded good yields of [Sm(Tp(Me2)(2)(kappa(2)-Y)] compounds (Y = 2-SC(5)H(4)N (3), 2-SeC(5)H(4)N (4)). 4 is the first selenopyridine complex of an f-block element. Sm(Tp(Me2)(2)(2-OC(5)H(4)N) (5) has been synthesized by salt metathesis of [Sm(Tp(Me2)(2)Cl] with the sodium salt of the 2-hydroxypyridine. The solid-state structures of 1, 3, 4, and 5 were determined by single-crystal X-ray diffraction analysis and revealed that the compounds are all eight-coordinate with dodecahedral geometry. The samarium atoms are bound in tridentate fashion to two pyrazolylborate ligands and in bidentate fashion by the third ligand. The solution behavior of the compounds was studied by (1)H NMR techniques. (1)H-(1)H exchange spectroscopy experiments give evidence for two distinct dynamic regimes occurring in solution.

Journal Article↗
PubMed1999

Discriminating the ecotoxicity due to metals and to low pH in acid mine drainage.

Several techniques have been developed to assess the ecotoxicity of contaminated watercourses. Most of these techniques involve chemical alterations of water samples, by diluting it or by adding chelating agents. These changes become particularly severe when assessing the toxicity of samples with very low pH and with high quantities of contaminants. Trying to overcome this problem, a novel toxicity test, specific for acid waters, was previously developed and field validated. The toxicity of acid samples is assessed using the survival time of Ceriodaphnia dubia. During this study, the novel test was applied to a field situation, where an aquatic system is seriously impacted with acid mine drainage. Its efficiency was tested and compared with two classical toxicity tests: the Microtox and the median lethal dilution with C. dubia. The survival time test was performed without adjusting pH and after adjusting pH to a fixed value (pH 2, 3, and 4). At pH 2 and 4 no acceptable results were obtained; at pH 3 it was possible to distinguish the toxicity due to pH from the toxicity due to other toxicants. The test conducted at local pH was able to discriminate toxicity sources only for highly contaminated samples. The toxicity evaluation of acid mine drainage samples was possible neither with the median lethal dilution test nor with Microtox.

Animals↗
PubMed1980

Specific mechanics for abutment uprighting.

General practitioners can use adjunctive orthodontics in preparation for complex comprehensive dental restorative procedures. Two orthodontic educators from opposite sides of the world explain and illustrate the biomechanics of controlled abutment uprighting. Solutions to the common mechanical and clinical problems are discussed.

Biomechanical Phenomena↗
PubMedDate not supplied

[The elderly patient at the General Hospital of Santo António. Analysis of one year of admissions].

A retrospective analysis was made on 3850 elderly patients who were admitted to the Santo António General Hospital during one year. There were 2029 women and 1821 men. Their mean age was 74 years. They represented 16.4% of the totality of the patients admitted in the same period of time at the same hospital. The main diagnosis presented on each discharge register was made according to the International Statistical Classification of Diseases, Injuries and Causes of Death, 9th Revision. For each of the 17 groups of diagnosis found and for the total group were drawn: number of cases, sex, mean age, the average length of stay, mortality and Departments they were admitted to. The circulatory diseases were the most frequent (24.4%). The average length of stay was 15 days. The mortality was 14.1%. The elderly patients represented about 30% of the admissions to the Departments of Internal Medicine, Cardiology, Vascular Surgery, Ophthalmology and Urology. The results were interpreted and some ideas about future medical care for this group of patients are presented.

Age Factors↗
PubMedDate not supplied

[Changes in the post-kidney transplantation body composition: different behavior between men and women].

A kidney transplant often leads to an increase in body weight, with an altered composition of the organism. This study assessed the body composition of a population with kidney transplant and an excess of weight (IMC > 25), using anthropometry, electric bio-impedance, and infrared interactance. The results were compared with the mean values (P50) for the Spanish population, and the differences between men and women were analyzed. The assessment of the body composition using anthropometry resulted in weight percentages, -mid-arm circumference, and -mid-arm muscle circumference of the upper arms, which were slightly higher than the P50, without there being any differences between the two sexes. The triceps fold showed values which were much higher than the average value, and this was more markedly seen in male. All patients showed an android type obesity pattern, and this was greater in men. The electric bio-impedance analysis and the infra-red interactance showed high fat levels for both sexes, without any statistically significant differences with respect to the percentages of fat mass, lean mass and water with both methods. The study has shown that the weight increase as a result of the kidney transplant, is mainly accompanied by an increase in the adipose tissue, and this is more marked in patients of the male sex, in such a way that the typical significant differences between both sexes with respect to the fat mass, commonly seen the general population, disappear.

Adipose Tissue↗