1,802 research outputs found

    Climate Change Threats to Semi-Arid Transhumance Grazing Systems: Proposals for Adaptation in Cabo Verde

    Get PDF
    Global warming has changed the rainfall regime in the Sahelian region, endangering and widespread poverty and chronic famines in Cape Verde, where rural communities\u27 well-being and food security depend on rainy agriculture. Local responses to rainfall new patterns and scarcity have been livestock reduction with significant revenue losses. Together with dry mist occurrences, these environmental constraints demand to define priority actions to adapt and mitigate climate change\u27s direct impacts. According to fifty household inquiries, this work explains the transhumant grazing practices on a semi-arid plateau in Tarrafal (Santiago, Cabo Verde), prospecting adaptation alternatives for sustainability. We related grazing patterns and pastoral infrastructures to the household\u27s socioeconomics, analyzing the livestock system - composition and management - and their relationship to rangeland utilization. Livestock of male-headed households is different from female-headed ones, mainly cattle in the firsts and goats in the lasts. Herds decreased during the 2016-2018 drought, including equine that lost interest in supporting farmers that abandoned the most remote agriculture patches. Based on a carrying capacity zoning, the geographical analysis assessed existing water supply structures\u27 suitability and designated new ones to improve transhumance effectiveness. New watering points along principal depressions allow to establish forage species - Parkinsonia aculeata, Opuntia ficus-indica, Pannisetum pedicellatum, and Desmanthus virgathus – and reduce stormwater runoff. It also means to improve natural resources by biodiversity conservation and wildlife management. These and other proposals could sustain and adapt the Tarrafal transhumant grazing system to climate change, reduce the farmers\u27 income loss, and improve food security

    Dependence of Ga-doped ZnO thin film properties on different sputtering process parameters: Substrate temperature, sputtering pressure and bias voltage

    Get PDF
    This paper reports on the effects of different sputtering deposition process parameters (substrate temperature, sputtering pressure and bias voltage) on the electrical, optical, structural and morphological properties of gallium-doped ZnO (ZnO:Ga) of ~1 μm thick. These highly transparent and conductive films were deposited on glass surfaces by d.c. pulsed magnetron sputtering from a GZO (ZnO(95.5):Ga2O3(4.5)) ceramic target in an argon atmosphere. X-ray diffraction experiments show that all films have a hexagonal wurtzite structure with the [001] preferred crystallographic direction, and themorphology of the films (obtained fromscanning electron microscope analysis) is sensitive to the process parameters. All ZnO:Ga films have an average transmittance above 80% in the visible region, and the lowest electrical resistivity of 3.03 × 10−4 Ω·cm was achieved for the sample submitted to the lowest bias voltage (−40 V), which corresponds to a carrier concentration and a carrier mobility of 6.99 × 1020 cm−3 and 29.49 cm2 V−1 s−1, respectively. A high substrate temperature, high sputtering pressure and lownegative bias voltage (within the range of studied parameters) proved to be very promising on obtaining optimized ZnO:Ga films, ensuring suitable properties for application as transparent electrodes in photovoltaic cells.The authors acknowledge the funding from the Portuguese Innovation Agency (AdI), project reference WinDSC-21539, co-funded by FEDER/POFC

    Biosorption of Cr(VI) by an E. coli biofilm supported on GAC

    Get PDF
    The increasing concern with environmental pollution significantly motivates the investigation and development of safe remediation technologies. The retention of contaminants by a biofilm supported on granular activated carbon is one of the promising technologies. This study aims the investigation and development of an innovative process for the removal of chromium (VI) from wastewater. The effect of the initial concentration of metal was tested, the polysaccharide and polymeric net of the E.Coli biofilm were quantified and the application of this system to a real effluent was made. The industrial effluent was provided by tannery factories. The support used for the biofilm formation was granular activated carbon (GAC) from MERCK with an average particle size of 2.5 mm, characterised by N2 adsorption (77K) with an ASAP Micromeritics 2001 which indicated a Langmuir area of 1270 m2g-1 and an average pore diameter of 2 nm. The use of activated carbon as a support is justified by the fact that this material is a versatile adsorbent due to its high surface area, porous structure, high adsorption capacity and surface chemical nature. The role of the biofilm was evaluated considering that microorganisms are quite adequate for heavy metals biosorption due to their ability to sorb metal ions, suitability for natural environments and low cost. Minicolumns (internal diameter = 2 cm, ht = 30 cm) were used for open systems studies, partially filled with GAC (15 g). The metal solutions were passed in upflow through the column with a flow rate of 5 ml/min (residence time of 19 min). Samples (5 ml) were taken, centrifuged and analyzed for metals using atomic absorption spectrophotometry, AAS. The results showed uptake values of 0.19 mg/gbiosorbent, 3.60 mg/gbiosorbent and 4.61 mg/gbiosorbent, respectively for the initial concentration of 10, 50 and 100 mg/l. The quantification of polysaccharides and polymeric net reveled a value of 4.77 mg/gbiosorbent for the polysaccharides and 142 mg/gbiosorbent, for the polymeric net. The polyssacharide and polymeric net give importante informations about the capacity of biofilm formation by the microrganism. The studies made with the industrial effluent showed values of Cr uptake of 0.093 mg/gbiosorbent, for an initial concentration of 4.2 mg/l. The value obtained for the removal percentage with the most diluted solution used (10 mg/l) was of 18% (after 10 hours of experiment) and the value of removal percentage obtained with the industrial effluent was of 9%, for the same period of time. This can be explainded by the fact that another compounds present in the industrial effluent than Cr(VI) can compete for the same active sites

    Tuberculose Muscular e Subcutânea Multifocal num Jovem Imunocompetente: Descrição de um Caso Clínico e Revisão da Literatura

    Get PDF
    Due to unfavorable conditions for survival and multiplication of Mycobacterium tuberculosis, muscle and soft tissue involvement is probably the rarest form of presentation of musculoskeletal tuberculosis, particularly without a clinically or radiologically apparent primary focus. As in other extrapulmonary forms of tuberculosis, its relative incidence is higher among immunocompromised patients. A progressive swelling is the most common complaint at presentation, which is otherwise mild and nonspecific. We present a case of multifocal (seven) subcutaneous and muscular tuberculous abscesses in a 29-year-old Indian patient who had no apparent underlying risk factors, nor any other organ involvement. Provisional diagnosis was initially made upon Mycobacterium tuberculosis complex nucleic acid detection in an aspirate of one of the collections and later confirmed by a positive culture on Lowenstein-Jensen medium. Two abscesses required aspiration and two others drained spontaneously. The patient responded well to nine months of anti-tuberculous therapy. An extensive review of the literature was made.info:eu-repo/semantics/publishedVersio

    Biosorption of Cr(VI) by three different bacterial species supported on granular activated carbon: a comparative study

    Get PDF
    The ability of three different bacterial species supported on granular activated carbon (GAC) to remove hexavalent chromium from low concentration liquid solutions was investigated, in batch and column studies. The microorganisms tested were Cr(VI) reducing types: Streptococcus equisimilis (CECT 926), Bacillus coagulans (CECT 12) and Escherichia coli (CECT 515). The results showed metal uptake values of 5.82, 5.35 and 4.12 mg/gbios., respectively, for S. equisimilis, B. coagulans and E. coli, for an initial metal concentration of 100 mg/l. In the same order and for the initial concentration of 50 mg/l, metal uptake values were 2.33, 1.98 and 3.60 mg/gbios.. Finally, for the initial metal concentration of 10 mg/l, those values were, respectively, 0.66, 1.51 and 1.12 mg/gbios.. Studies made with an industrial effluent, with the aim of testing these biofilms in a real situation, showed values of Cr uptake of 0.083, 0.090 and 0.110 mg/gbios., respectively, for S. equisimilis, B. coagulans and E. coli, for an initial concentration of 4.2 mg/l of total Cr. The quantification of polysaccharides, playing a key role in the whole process, was made and it was concluded that the production of polysaccharides is higher for B. coagulans followed by S. equisimilis and E. coli (9.19, 7.24 and 4.77 mg/gbios.). The batch studies data were described using the Freundlich, Langmuir, Redlich–Peterson, Dubinin–Radushkevich, Sips andToth model isotherms. The best fit was obtained with Sips and Toth model isotherms, respectively, for the S. equisimilis and for the B. coagulans biofilms. For the E. coli biofilm the Freundlich, Redlich–Peterson, Sips and Toth models fitted very well to the experimental data. The Adams–Bohart,Wolborska and Yoon and Nelson models were applied to column studies data. Those models were found suitable for describing the dynamic behaviour of the columns with respect to the inlet chromium concentration. Obtained results showed that the biofilms tested are very promising for the removal of Cr(VI) in diluted industrial wastewater. Despite differences in the cell wall structure and composition, the three bacteria exhibit comparable sorption affinities towards chromium, in the open systems studies. The Gram-positive bacteria tested (B. coagulans and S. equisimilis) presented best metal removal percentages in batch studies.Fundação para a Ciência e a Tecnologia (FCT)Ministério da Ciência e Tecnologia FEDE

    Biosorption of Cr(VI) by a Bacillus coagulans biofilm supported on granular activated carbon (GAC)

    Get PDF
    The ability of a biofilm of Bacillus coagulans supported on granular activated carbon (GAC) to biosorb Cr(VI) was investigated in batch and column studies so it may be applied to low metal concentration wastewater treatment. The quantification of polysaccharides and polymeric net revealed a value of 9.19 mg/gbiosorbent for the polysaccharides and 75 mg/gbiosorbent, for the polymeric net. The results obtained with open systems showed uptake values of 1.50, 1.98 and 5.34 mg/gbiosorbent, respectively, for initial concentrations of 10, 50 and 100 mg/L of Cr(VI). Column studies performed with an industrial effluent showed values of Cr uptake of 0.090 mg/gbiosorbent, for an initial concentration of 4.2 mg/L. The presence of functional groups on the cell wall surface of the biomass that may interact with the metal ion, was confirmed by FTIR. The equilibrium studies in batch systems were described by Freundlich, Langmuir, Reddlich–Peterson, Dubinin–Radushkevich, Sips and Toth model isotherms. Best fit was obtained with Toth model isotherm. Data from column studies were described by Adams–Bohart and Wolborska models. These models were found suitable for describing the dynamic behaviour of the columns with respect to the inlet chromium concentration. The whole study showed that the biofilm tested is very promising for the removal of Cr(VI) in industrial wastewater.FEDER.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/QUI/44840/2002

    Non-AIDS-related comorbidities in people living with HIV-1 aged 50 years and older: The AGING POSITIVE study.

    Get PDF
    OBJECTIVE: To characterize the profile of non-AIDS-related comorbidities (NARC) in the older HIV-1-infected population and to explore the factors associated with multiple NARC. METHODS: This was a multicentre, cross-sectional study including HIV-1-infected patients aged ≥50 years, who were virologically suppressed and had been on a stable antiretroviral therapy (ART) regimen for at least 6 months. A multiple regression model explored the association between demographic and clinical variables and the number of NARC. RESULTS: Overall, 401 patients were enrolled. The mean age of the patients was 59.3 years and 72.6% were male. The mean duration of HIV-1 infection was 12.0 years and the median exposure to ART was 10.0 years. The mean number of NARC was 2.1, and 34.7% of patients had three or more NARC. Hypercholesterolemia was the most frequent NARC (60.8%), followed by arterial hypertension (39.7%) and chronic depression/anxiety (23.9%). Arterial hypertension and diabetes mellitus were the most frequently treated NARC (95.6% and 92.6% of cases, respectively). The linear regression analysis showed a positive relationship between age and NARC (B=0.032, 95% confidence interval 0.015-0.049; p=0.0003) and between the duration of HIV-1 infection and NARC (B=0.039, 95% confidence interval 0.017-0.059; p=0.0005). CONCLUSIONS: A high prevalence of NARC was found, the most common being metabolic, cardiovascular, and psychological conditions. NARC rates were similar to those reported for the general population, suggesting a larger societal problem beyond HIV infection. A multidisciplinary approach is essential to reduce the burden of complex multi-morbid conditions in the HIV-1-infected population.info:eu-repo/semantics/publishedVersio

    Arterio-arterial graft – an option for hemodialysis patients with exhaustion of venous patrimony

    Get PDF
    Introduction: Vascular access (VA) for hemodialysis (HD) is the lifeline for End Stage Renal Disease (ESRD) patients. Long-term HD patients often have exhaustion of their venous patrimony for an autologous VA construction and, sometimes, even for a central venous catheter (CVC) placement. Case report: We describe the case of a 43-year-old woman with ESRD due to lupus nephritis, on maintenance HD since 2009. She also had secondary antiphospholipid syndrome and was chronically anticoagulated. Nevertheless, the patient had multiorgan thrombotic events (without sequelae) and several episodes of irreversible thrombosis of arteriovenous fistulas. Her HD course was also marked by multiple severe CVC infections, at diferente locations; a hemoperitoneum during cholecystectomy, and an immediate thrombosis of the renal artery of a kidney transplant. She was admitted to our hospital after an irreversible dysfunction of a right jugular CVC, with documentation of thrombosis of the superior and inferior vena cava. Exhaustion of the venous patrimony for HD was assumed and it was decided to make an arterio-arterial graft (AAG) of early cannulation. The first cannulation of the AAG was performed two days after surgical intervention, with no complications. The patient performed a twelve hour per week HD treatment with good efficiency. Conclusion: AAG is an alternative for HD patients who have exhausted all their venous patrimony and it can be considered prior to the placement of a CVC as their sole remaining vascular access.info:eu-repo/semantics/publishedVersio
    • …
    corecore