How people move around in large Brazilian cities reflects a process of production and appropriation of urban space. The transport system is characterised by the increasing rate of individual ...motorisation and the precariousness of public transport services. The general objective of this paper is to evaluate the level of road cycling in the city of Belo Horizonte/Minas Gerais/Brazil, based on the proposition and analysis of indicators to assess the degree of adequacy of urban roads for bicycle use as a transport mode. The results indicate that many of the roads in Belo Horizonte have good cycling levels. Given its topography and climate, these findings go against commonly held views that consider the municipality inappropriate for cycling as a mode of transport. In reality, Belo Horizonte has a very underused high cycling potential, especially if there were investments to expand the exclusive/preferred road infrastructure.
Recuperando uma experiência de pesquisa etnográfica no estado de Santa Catarina, Brasil, neste artigo discute-se a relação entre conhecimentos, memórias, imitações e processos criativos entre ...agricultores ecológicos. A pesquisa foi realizada com agricultores familiares ecologistas entre 2008 e 2009 em diferentes situações, especialmente em reuniões, visitas técnicas e em feiras, além de terem sido realizadas entrevistas individuais. Conhecimentos se articulam a memórias e às práticas de gerações anteriores, mas o senso de experimentação dos agricultores é fundamental em atividades cotidianas, organizando-se numa dança entre imitação, adaptação e criação. Os conhecimentos que circulam fazem parte de um patrimônio de relações e da cultura: atualizam-se, recompõem-se, renovam-se e geram diversidade. Tal processo é oriundo de relações na agricultura que, portanto, envolve seres não-vivos e seres vivos não-humanos cuja dinâmica de geração, maturação e interações não é totalmente controlada pelos humanos.
A new type of photocatalyst was obtained by heterojunction between δ-FeOOH and NiO using a ball mill. The proportion of NiO in relation to δ-FeOOH was varied, resulting in the materials FN5, FN10 and ...FN20 (5, 10 and 20% w/w, NiO:δ-FeOOH). The diffractograms confirmed the heterojunction by the presence of crystalline planes of NiO. In addition, the heterojunction formed also reflected in the increase in the band gap of the material and, consequently, in the performance of photocatalysis, especially for FN20, which reached about 72% of dye removal in 4 h. Theoretical studies were carried out to elucidate the mechanisms of photocatalysis by optimization and single-point calculations of NiO and δ-FeOOH structures. The results indicated that, when the light is on, the holes pass from the valence band of NiO to the valence band of δ-FeOOH, whose photoexcited electrons go from its conduction band to the conduction band of NiO. This effect results in decreasing electron/hole recombination rates, improving the photocataylic process when compared to the δ-FeOOH photocatalyst alone. In addition, it was observed that the water oxidation occurs on δ-FeOOH surface, and that this reaction can be thermodynamically favorable.
BACKGROUNDAcute kidney injury (AKI) is a frequent complication during the postoperative period following liver transplantation. Occurrence of AKI in intensive care unit (ICU) patients is associated ...with increased mortality and higher costs. OBJECTIVETo evaluate occurrences of moderate or severe AKI among patients admitted to the ICU after liver transplantation and investigate characteristics associated with this complication. DESIGN AND SETTINGSingle-center retrospective cohort study in a public hospital, Belo Horizonte, Brazil. METHODSForty-nine patients admitted to the ICU between January 2015 and April 2017 were included. AKI was defined from a modified Kidney Disease Improving Global Outcomes (KDIGO) score (i.e. based exclusively on serum creatinine levels). RESULTSEighteen patients (36.7%) developed AKI KDIGO 2 or 3; mostly KDIGO 3 (16 out of the 18 patients). Lactate level within the first six hours after ICU admission (odds ratio, OR: 1.3; 95% confidence interval, CI: 1.021-1.717; P = 0.034) and blood transfusion requirement within the first week following transplantation (OR: 8.4; 95% CI: 1.687-41.824; P = 0.009) were independently associated with development of AKI. Patients with AKI KDIGO 2 or 3 underwent more renal replacement therapy (72.2% versus 3.2%; P < 0.01), had longer hospital stay (20 days versus 15 days; P = 0.001), higher in-hospital mortality (44.4% versus 6.5%; P < 0.01) and higher mortality rate after one year (44.4% versus 9.7%; P = 0.01). CONCLUSIONNeed for blood transfusion during ICU stay and hyperlactatemia within the first six postoperative hours after liver transplantation are independently associated with moderate or severe AKI. Developing AKI is apparently associated with poor outcomes.
Effective control of the inflammatory process in Crohn's disease (CD) is reflected in intestinal mucosal healing. The performances of faecal calprotectin (fcal), clinical and serologic parameters in ...the inflammatory activity evaluation and their correlation to the simple endoscopic score (SES-CD) are the goals of this study.
Patients with CD referred for ileocolonoscopy were prospectively included and distributed according to the degree of endoscopic inflammatory activity into remission, mild activity, and moderate to severe activity groups. The different degrees of endoscopic activity were correlated with the following indexes: Crohn's disease activity index (CDAI), fCal, serum C-reactive protein (CRP), and haemogram. The control group comprised individuals without known intestinal disease who were referred for colorectal cancer screening.
Eighty colonoscopies were performed in patients with CD and 21 in the control group. The control group had a lower median fCal (59.7 mcg/g) than patients with CD (683 mcg/g, p < 0.001). A moderate Spearman correlation occurred between SES-CD and CRP (r = 0.525), fCal (r = 0.450), and CDAI (r = 0.407), while a weak correlation was found with the platelet count (r = 0.257). Only fCal distinguished patients in remission from those with mild activity (236.6 mcg/g × 654.9 mcg/g, p = 0.014) or moderate to severe activity (236.6 mcg/g × 1128 mcg/g, p < 0.001). An fCal cut-off of 155 mcg/g was sensitive (96%) and accurate (78%) for the diagnosis of endoscopic activity.
fCal provides greater diagnostic accuracy than the other activity markers for endoscopic activity of patients with CD, moderate correlation to SES-CD, and a capacity to discriminate patients in remission from those with mild or moderate to severe activity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The exploitation of renewable sources, such as solar light, is strategically attractive in the current global energy crisis scenario. However, solar technologies that use earth-abundant materials ...that can efficiently harvest sunlight still need to be investigated. In this regard, photocatalytic fuel cells (PFCs) with dual-photoelectrode design are promising technologies able to efficiently generate electricity and/or chemical energy from solar irradiation. Both electrodes can absorb sunlight in a typical dual-photoelectrode PFC design, theoretically improving cell absorption and performance. Unfortunately, in practice, a suitable combination of electrodes, electrolytes, and fuel is still challenging regarding dual-photoelectrode PFCs. Herein, we investigated a dual-photoelectrode H
2
O
2
fuel cell using a BiVO
4
-based photoanode and a CuO-based photocathode under different electrolyte conditions. The results have shown that electrolyte choice plays a significant role in cell performance and stability. In acetate electrolyte, the cell has delivered a stable short circuit photocurrent density as high as 3.4 mA cm
− 2
, a power density of 0.26 mW cm
− 2
, and 0.48 V open-circuit potential. In such a way, this device can provide a high unassisted performance to convert sunlight using earth-abundant materials in both anode and cathode, and at the expense of carbon-free fuel. Therefore, these findings establish promising directions toward the practical application of cost-effective unbiased photoelectrochemical technologies.
Graphical abstract
Dual-photoelectrode H
2
O
2
photocatalytic fuel cell delivers an stable 3.4 mA cm
−2
short circuit current using BiVO
4
and Cu
2
O-based photoelectrodes in acetate electrolyte.
A significant enhancement in the catalytic performance due to enzymes immobilization is a great way to enhance the economics of biocatalytic processes. The soybean peroxidase (SP) immobilization ...under ferroxyte and the ferulic acid removal by the enzyme free and immobilized were investigated. The immobilization via silica-coated ferroxyte nanoparticles was effective, and immobilization yield of 39%. The scanning electron microscopy (SEM) images showed significant changes in the materials morphology. Substantial differences were observed in the particles’ Fourier Transform Infrared (FTIR) spectra. The magnetic catalyst revealed a better performance than the free enzyme in the ferulic acid conversion, presenting a good
V
max
/
K
m
ratio when compared with the free enzyme. The reuse evaluated by ten cycles exhibited excellent recycling, remaining constant between the sixth and seventh cycles. The use of magnetic nanocatalyst becomes possible to eliminate the high operational costs, and complicated steps of the conventional enzymatic processes. Thus, a viable industrial route for the use of the enzyme as catalyst is possible.
Photoassisted hydrogen peroxide fuel cells are promising for converting chemical energy into electricity due to the high energy density and safe storage of H2O2. Despite this, the power density ...produced by H2O2 photocatalytic fuel cells is still low. Here, we demonstrate a membrane-free hydrogen peroxide photocatalytic cell using a W-BiVO4/V2O5 photoanode and a Cu2O/CuO photocathode under tandem lighting, which operates in an air-saturated NaHCO3/H2O2 aqueous solution (pH 8). H2O2 plays a dual role as an electron donor and acceptor, thus eliminating the need to use a membrane to separate the photoanode from the photocathode. Under simulated sunlight, the cell produces a short-circuit photocurrent density of 8.05 mA cm−2, an open-circuit potential of 0.41 V, and a power density of 0.84 mW cm−2. The power density of dual-photoelectrode cells is significantly higher than the single-photoelectrode cells due to the higher efficiency of charge separation and light absorption provided by the tandem cell. Finally, this simple cell design should be attractive for constructing efficient, green, and sustainable H2O2 photocatalytic fuel cells.
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•W-BiVO4/V2O5 photoanodes were prepared for hydrogen peroxide oxidation.•Cu2O/CuO photocathodes were prepared for hydrogen peroxide reduction.•Hydrogen peroxide works as both fuel and electron acceptor in the photocell.•H2O2 photocell produces a short-circuit photocurrent as high as 8.05 mA cm−2.•Pt electrode can be replaced by Cu2O/CuO photocathode without loss of efficiency.
Owing to their high surface area, stability, and functional groups on the surface, iron oxide hydroxide nanoparticles have attracted attention as enzymatic support. In this work, a chemometric ...approach was performed, aiming at the optimization of the horseradish peroxidase (HRP) immobilization process on Δ-FeOOH nanoparticles (NPs). The enzyme/NPs ratio (X1), pH (X2), temperature (X3), and time (X4) were the independent variables analyzed, and immobilized enzyme activity was the response variable (Y). The effects of the factors were studied using a factorial design at two levels (-1 and 1). The biocatalyst obtained was evaluated for the ferulic acid (FA) removal, a pollutant model. The materials were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The SEM images indicated changes in material morphology. The independent variables X1 (-0.57), X2 (0.71), and X4 (0.42) presented the significance effects estimate. The variable combinations resulted in two significance effects estimates, X1*X2 (-0.57) and X2*X4 (0.39). The immobilized HRP by optimized conditions (X1 = 1/63 (enzyme/NPs ratio, X2 = pH 8, X4 = 60 °C, and 30 min) showed high efficiency for FA oxidation (82%).
•Acetic acid steam reforming was studied over Ni and Co catalysts.•Ni–Co catalysts were more actives than catalysts containing only nickel at 500°C.•25Ni5CoAl catalyst showed the best selectivity to ...H2 and CO2 at 500°C.•20NiAl and 30NiAl catalysts showed higher selectivity to H2 at 600°C.
The aim of this work was to study the performance of Ni and Co catalysts supported on alumina to convert acetic acid into hydrogen. Acetic acid was chosen as representative compound for the steam reforming of bio-oil derived from biomass pyrolysis. In this study alumina supported Ni, Co and bimetallic Ni–Co catalyst were prepared by wet impregnation and characterized by XRD, SEM–EDX, BET and TPR-H2 analysis. Steam reforming of acetic acid was conducted in a fixed bed reactor at a temperature of 500°C and 600°C. Among the catalysts studied, the best catalytic performance for the acetic acid steam reforming at 500°C was obtained by the bimetallic catalysts, which presented an effluent gaseous mixture with the highest H2 selectivity and reasonable low CO formation.
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