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Acute kidney injury is characterised by a sudden injury to the renal parenchyma and causes defects in its excretory, metabolic and endocrine function. Dialysis therapy has been instituted in small animal clinics with the aim of removing the metabolic waste and correcting the electrolyte disturbances stemming from renal dysfunction. Peritoneal dialysis is a therapy based on the use of the peritoneum as a semipermeable membrane through which solutes and fluids are exchanged between blood from the peritoneal capillaries and the dialysis solution. This report describes a case of acute kidney injury stemming from drug therapy in a 13-year-old female mongrel canine. The patient exhibited anorexia, emesis, prostration and anuria and had a history of prolonged treatment with meloxicam. The patient also presented with azotaemia and metabolic acidosis. When anuria continued to persist after drug therapy (volume restoration, chemical and osmotic diuresis and renal vasodilation), peritoneal dialysis was instituted. Three cycles of peritoneal dialysis were performed; during the second cycle, the patient's anuria was reversed, and at the end of the third cycle she showed a significant reduction in azotaemia, hyperkalaemia and an improved metabolic acidosis. Therefore, peritoneal dialysis showed satisfactory clinical results and reversed anuria, reduced azotaemia and electrolyte disturbances, thereby providing clinical improvement. [ABSTRACT FROM AUTHOR]

Author(s): Wai Lek Ng; M. A. Lourenço; R. M. Gwilliam; S. Ledain; G. Shao; K. P. Homewood Nature 410, 192-194 (2001). Silicon light-emitting diodes (LED) show light emission at the [...]

The growing use of Modular Multilevel Cascade Converter (MMCC) topologies in applications such as High Voltage Direct Current Transmission, Static Var Compensation, Alternating Current (AC) Drives and renewable energy systems, among others, turns their study relevant. However, as the number of Power Submodules in the MMCCs increases, the applied control strategies, data communication and digital hardware complexity increases as well. This paper proposes a flexible and scalable platform, that is adequate for implementing different MMCC topologies (single star, single delta or double star), communication schemes (star or ring) and control strategies (centralized or distributed). The Processing Board explores the availability of Field Programmable Gate Arrays, Digital Signal Processors and ARM microcontrollers. The Power and Measurement Submodules processing capability is provided by Complex Programmable Logic Devices and ARM microcontrollers. Description of the tasks implemented in the processing devices and experiments are presented for a test case, in which a double star topology with star communication and centralized processing strategy is tested using fixed switching frequency and equally displaced carriers.

The objective of this article is to present a flexible didactic platform for thyristor-based circuits. When compared to the existing academic and commercial teaching platforms the proposed one is modular and shows more flexibility. Using the same basic thyristor module, several topologies can be built, including solid-state relays, thyristor bridge rectifiers, and others. All development steps are detailed. Examples of teaching applications, such as the operation of a controlled rectifier, are presented to demonstrate the functionality and didactic usage. Experimental results are also included for the presented applications.

This paper addresses a multiscale approach for heat recovery systems, used in two distinct applications. In both applications, a microscale approach is used (microchannel heat sinks and heat pipes) for macroscale applications (cooling of a photovoltaic—PV cell), and the thermal energy of exhaust gases of an internal combustion engine is used for thermoelectric generators with variable conductance heat pipes. Several experimental techniques are combined such as visualization, thermography with high spatial and temporal resolution, and the characterization of the flow hydrodynamics, such as the friction losses. The analysis performed evidences the relevance of looking at the physics of the observed phenomena to optimize the heat sink geometry. For instance, the results based on the dissipated heat flux and the convective heat transfer coefficients obtained in the tests of the microchannel-based heat sinks for cooling applications in PV cells show an improvement in the dissipated power at the expense of controlled pumping power, for the best performing geometries. Simple geometries based on these results were then used as inputs in a genetic algorithm to produce the optimized geometries. In both applications, the analysis performed evidences the potential of using two-phase flows. However, instabilities at the microscale must be accurately addressed to take advantage of liquid phase change. In this context, the use of enhanced interfaces may significantly contribute to the resolution of the instability issues as they are able to control bubble dynamics. Such an approach is also addressed here.

The current state of the art shows that unbalance and distortion on the voltage waveforms at the terminals of a grid-connected inverter disturb its output currents. This paper compares AC linear current regulators for three-phase three-wire voltage source converters with three different reference frames, namely: (1) natural (abc), (2) orthogonal stationary (αβ), and (3) orthogonal synchronous (dq). The quantitative comparison analysis is based on mathematical models of grid disturbances using the impedance-based analysis, the computational effort assessment, as well as the steady-state and transient performance evaluation based on experimental results. The control scheme devised in the dq-frame has the highest computational effort and inferior performance under negative-sequence voltage disturbances, whereas it shows superior performance under positive-sequence voltages among the reference frames evaluated. In contrast, the stationary natural frame abc has the lowest computational effort due to its straightforward implementation, with similar results in terms of steady-state and transient behavior. The αβ-frame is an intermediate solution in terms of computational cost.

O conhecimento dos níveis de concentração de metais pesados no ambiente e sua disseminação no solo e nas águas são de primordial importância em estudos ambientais, por constituir um dos indicadores de “medição” do equilíbrio da biodiversidade e da estabilidade dos ecossistemas. O presente trabalho teve como objetivo, estudar a distribuição espacial de dois metais pesados (Cobre e Cádmio) ao longo das margens do rio Meuse, por forma a medir os níveis de contaminação por esses metais. Foram usados dados da concentração de Cd e Cu amostrados em 155 pontos georeferenciados. Estes dados foram obtidos no programa R no pacote “gstat” cuja base de dados denomina-se “Meuse”. A metodologia de análise dos dados consistiu em ajustar semivariogramas para análise da dependência espacial, e foram ajustados os modelos esféricos e gaussiano para a concentração de Cobre e Cádmio, respectivamente. O grau de dependência espacial foi classificado como forte para a concentração de Cobre e moderada para a concentração de Cádmio. A estimação da concentração destes metais pesados em pontos não amostrados, foi feita usando o método de krigagem produzindo mapas de distribuição espacial da concentração de Cobre e Cádmio que apresentaram um padrão similar entre si. Verificou-se que dentre os dois metais pesados, o Cobre apresenta concentrações muito altas que chegam a atingir os 130 mg/Kg de solo.

Phase Locked Loops (PLLs) with in-loop Moving Average Filter (MAF) and a Proportional Integral (PI) controller are effective methods to achieve synchronization in grid-connected converters, since they have simple implementation, low computational burden and excellent filtering capability. However, they are known to be slow. The reasons are the MAF time delay and the PI controller tuning method, which makes the design of a fast control loop challenging. This paper demonstrates that the second-order Padé approximation is enough to achieve an accurate model for the MAF, and presents a controller design technique that results in the minimum settling times achievable for a MAF-PLL with a PI controller. Simulation and experimental results validate the proposed approach.

Peste des Petits Ruminants (PPR), a transboundary animal disease affecting mainly goats and sheep is caused by a morbillivirus and threatens food security and livelihoods as morbidity and mortality rates can reach 90%. There are no records of PPR in Mozambique, but the disease situation in Tanzania and the ability of PPR virus to rapidly spread across countries constitute a high risk for about 4.7 million goats and sheep in Mozambique. A total of 4,995 goats and sheep were sampled in several provinces during 2015 and 2017 to assess the status of PPR virus (PPRV) in Mozambique and to contribute to surveillance along the border with Tanzania. The sera were screened for anti-PPRV antibodies using a commercial PPR competition ELISA (c-ELISA) and the haemagglutinin based PPR blocking ELISA (HPPR-bELISA). The swabs were tested using one-step RT-PCR for detection of PPRV RNA. The overall percentage of animals with anti-PPRV antibodies by c-ELISA, was 0.46% [0.30–0.70]. However, all the sera positive on c-ELISA were confirmed to be negative by the HPPR-bELISA. Considering that all the swabs were negative for detection of PPRV, no clinical cases were observed during passive surveillance and active sampling, and no symptoms were reported, these results suggest that PPRV is not present in Mozambique.