Influence of Caffeine and Chondroitin Sulfate on Swine Sperm Capacitation and In Vitro Embryo Production

Background: The establishment of an in vitro production (IVP) of embryo in swine allows the generation of embryos with the same quality as in vivo produced embryos with less costs and time. In order to achieve successful fertilization under normal circumstances in vivo, mammalian spermatozoa must first undergo capacitation and then acrosome reaction. The purpose of this study was compared the efficacious of IP/CFDA fluorescence and Coomassie Blue G (CB) staining to detect capacitated sperm cells in refrigerated and fresh semen. Morever, it was investigated the efficacious of caffeine and chondroitin sulphate to promote in vitro sperm capacitation and in vitro embryo produced (IVP) of swine embryos. Materials, Methods & Results: A sperm-rich fraction from ejaculate was obtained using the gloved-hand method and the gel-free fraction was separated using sterile gauze. The semen was diluted in BTS at a final concentration of 1.5 x 10(8) cells/mL. The sperm suspension was incubated for 2 h at 25 degrees C, refrigerated and maintained for 1 h at 15-18 degrees C (refrigerated group) or used immediately (fresh group). Sperm capacitation was assessed by IP/CFDA fluorescence and CB staining for both fresh and refrigerated semen. For PI/CFDA evaluation, a final solution containing 1.7 mM formaldehyde, 7.3 mM PI and 20 mM CFDA in 950 mu L saline was prepared. In the dark, 40 mu L PI/CFDA final solution was added to 10 mu L semen and after 8 min, slides were analyzed on epifluorescence microscopy. For CB evaluation, sperm cells were fixed in 4% paraformaldehyde for 10 min and centrifuged twice at 320 x g in ammonium acetate pH 9 for 8 min. A smear was made and stained with 2.75 mg/mL CB in solution containing 12.5% methanol, 25% glacial acetic acid and 62.5% water, for 2 min. The smear was washed in running water, air dried and sealed with Permount (R), diluted 2:1 in xilol to avoid staining oxidation. Our results showed that refrigeration did not affect sperm capacitation and comparing staining methods, the PI/CFDA combination was more efficient to detect capacitated sperm, when compared to CB staining. In experiment 2, we evaluated the effect of different incubation time (1 - 5 h) with chondroitin sulfate and caffeine on sperm capacitation. For in vitro fertilization, oocytes were obtained from slaughterhouse ovaries. Oocytes with a thick and intact cumulus oophurus layer and cytoplasm with homogenous granules were selected for in vitro maturation for 44 h. According to the results of experiment 2, it was used for in vitro fertilization refrigerated semen was capacitated with 50 mu g/mL chondroitin sulfate for 2 h or capacitated with 5 mu g/mL caffeine for 3 h. Six hours after insemination, cumulus oophorus cells were mechanically removed and oocytes were washed and incubated in microdrops of culture medium. Embryo development after fertilization with sperm capacitated with caffeine or chondroitin sulfate was evaluated on days 3, 5 and 7 of culture. No differences were observed in days 3 or 5 of in vitro culture. However, it was observed an increase on blastocyst rate on Day 7 of culture when caffeine was used as the capacitor agent. Discussion: Molecular basis of sperm capacitation is still poor understood. Sperm capacitation can occur in vitro spontaneously in defined media without addition of biological fluids. We observed that sperm capacitation increased as incubation period enlarged and it was observed using Coomassie blue G and PI/CFDA for fresh semen and for refrigerated semen. It can be concluded that the cooling of semen did not change their pattern of sperm capacitation and this is best assessed by IP/CFDA than by CB. In addition to the use of caffeine in sperm capacitation produces more blastocysts than the chondroitin sulfate after in vitro fertilization.

A DC Voltage-Multiplier Circuit Working as a High-Voltage Pulse Generator

The intensive use of semiconductor devices enabled the development of a repetitive high-voltage pulse-generator topology from the dc voltage-multiplier (VM) concept. The proposed circuit is based on an odd VM-type circuit, where a number of dc capacitors share a common connection with different voltage ratings in each one, and the output voltage comes from a single capacitor. Standard VM rectifier and coupling diodes are used for charging the energy-storing capacitors, from an ac power supply, and two additional on/off semiconductors in each stage, to switch from the typical charging VM mode to a pulse mode with the dc energy-storing capacitors connected in series with the load. Results from a 2-kV experimental prototype with three stages, delivering a 10-mu s pulse with a 5-kHz repetition rate into a resistive load, are discussed. Additionally, the proposed circuit is compared against the solid-state Marx generator topology for the same peak input and output voltages.

Design of improved rail-to-rail low-distortion and low-stress switches in advanced CMOS technologies

This paper describes the efficient design of an improved and dedicated switched-capacitor (SC) circuit capable of linearizing CMOS switches to allow SC circuits to reach low distortion levels. The described circuit (SC linearization control circuit, SLC) has the advantage over conventional clock-bootstrapping circuits of exhibiting low-stress, since large gate voltages are avoided. This paper presents exhaustive corner simulation results of a SC sample-and-hold (S/H) circuit which employs the proposed and optimized circuits, together with the experimental evaluation of a complete 10-bit ADC utilizing the referred S/H circuit. These results show that the SLC circuits can reduce distortion and increase dynamic linearity above 12 bits for wide input signal bandwidths.

Repetitive Solid State Pulse Modulator Based on a DC Voltage Multiplier

A newly developed solid-state repetitive high-voltage (HV) pulse modulator topology created from the mature concept of the d.c. voltage multiplier (VM) is described. The proposed circuit is based in a voltage multiplier type circuit, where a number of d.c. capacitors share a common connection with different voltage rating in each one. Hence, besides the standard VM rectifier and coupling diodes, two solid-state on/off switches are used, in each stage, to switch from the typical charging VM mode to a pulse mode with the d.c. capacitors connected in series with the load. Due to the on/off semiconductor configuration, in half-bridge structures, the maximum voltage blocked by each one is the d.c. capacitor voltage in each stage. A 2 kV prototype is described and the results are compared with PSPICE simulations.

Grid Integration of Offshore Wind Farms Using Modular Marx Multilevel Converters

This paper proposes the use of a Modular Marx Multilevel Converter, as a solution for energy integration between an offshore Wind Farm and the power grid network. The Marx modular multilevel converter is based on the Marx generator, and solves two typical problems in this type of multilevel topologies: modularity and dc capacitor voltage balancing. This paper details the strategy for dc capacitor voltage equalization. The dynamic models of the converter and power grid are presented in order to design the converter ac output voltages and the dc capacitor voltage controller. The average current control is presented and used for power flow control, harmonics and reactive power compensation. Simulation results are presented in order to show the effectiveness of the proposed (MC)-C-3 topology.

A New Modular Marx Derived Multilevel Converter

A new Modular Marx Multilevel Converter, M(3)C, is presented. The M(3)C topology was developed based on the Marx Generator concept and can contribute to technological innovation for sustainability by enabling wind energy off-shore modular multilevel power switching converters with an arbitrary number of levels. This paper solves both the DC capacitor voltage balancing problem and modularity problems of multilevel converters, using a modified cell of a solid-state Marx modulator, previously developed by authors for high voltage pulsed power applications. The paper details the structure and operation of the M(3)C modules, and their assembling to obtain multilevel converters. Sliding mode control is applied to a M(3)C leg and the vector leading to automatic capacitor voltage equalization is chosen. Simulation results are presented to show the effectiveness of the proposed M(3)C topology.

Matrix Converter-Based Unified Power-Flow Controllers: Advanced Direct Power Control Method

This paper presents a direct power control (DPC) for three-phase matrix converters operating as unified power flow controllers (UPFCs). Matrix converters (MCs) allow the direct ac/ac power conversion without dc energy storage links; therefore, the MC-based UPFC (MC-UPFC) has reduced volume and cost, reduced capacitor power losses, together with higher reliability. Theoretical principles of direct power control (DPC) based on sliding mode control techniques are established for an MC-UPFC dynamic model including the input filter. As a result, line active and reactive power, together with ac supply reactive power, can be directly controlled by selecting an appropriate matrix converter switching state guaranteeing good steady-state and dynamic responses. Experimental results of DPC controllers for MC-UPFC show decoupled active and reactive power control, zero steady-state tracking error, and fast response times. Compared to an MC-UPFC using active and reactive power linear controllers based on a modified Venturini high-frequency PWM modulator, the experimental results of the advanced DPC-MC guarantee faster responses without overshoot and no steady-state error, presenting no cross-coupling in dynamic and steady-state responses.

An efficient method for optimal location and sizing of fixed and switched shunt capacitors in large distribution systems

This paper proposes a computationally efficient methodology for the optimal location and sizing of static and switched shunt capacitors in large distribution systems. The problem is formulated as the maximization of the savings produced by the reduction in energy losses and the avoided costs due to investment deferral in the expansion of the network. The proposed method selects the nodes to be compensated, as well as the optimal capacitor ratings and their operational characteristics, i.e. fixed or switched. After an appropriate linearization, the optimization problem was formulated as a large-scale mixed-integer linear problem, suitable for being solved by means of a widespread commercial package. Results of the proposed optimizing method are compared with another recent methodology reported in the literature using two test cases: a 15-bus and a 33-bus distribution network. For the both cases tested, the proposed methodology delivers better solutions indicated by higher loss savings, which are achieved with lower amounts of capacitive compensation. The proposed method has also been applied for compensating to an actual large distribution network served by AES-Venezuela in the metropolitan area of Caracas. A convergence time of about 4 seconds after 22298 iterations demonstrates the ability of the proposed methodology for efficiently handling large-scale compensation problems.

Start-up circuit for low-power indoor light energy harvesting applications

A start-up circuit, used in a micro-power indoor light energy harvesting system, is described. This start-up circuit achieves two goals: first, to produce a reset signal, power-on-reset (POR), for the energy harvesting system, and secondly, to temporarily shunt the output of the photovoltaic (PV) cells, to the output node of the system, which is connected to a capacitor. This capacitor is charged to a suitable value, so that a voltage step-up converter starts operating, thus increasing the output voltage to a larger value than the one provided by the PV cells. A prototype of the circuit was manufactured in a 130 nm CMOS technology, occupying an area of only 0.019 mm(2). Experimental results demonstrate the correct operation of the circuit, being able to correctly start-up the system, even when having an input as low as 390 mV using, in this case, an estimated energy of only 5.3 pJ to produce the start-up.

Fonte de carga de condensadores de alta tensão com compensação de fator potência

Trabalho Final de Mestrado para a obtenção do grau de Mestre em Engenharia Electrotécnica Ramo de Automação e Electrónica Industrial

Análise e optimização global de uma linha de extrusão

Os objectivos principais deste estudo são a caracterização de uma das linhas de extrusão existentes na Cabelte, nomeadamente a linha de extrusão de referência EP5, composta por duas extrusoras. Pretende-se fazer a determinação de indicadores energéticos e de processo e a optimização do consumo energético, no que diz respeito à energia consumida e às perdas térmicas relativas a esta linha. Para fazer a monitorização da linha de extrusão EP5 foi colocado no quadro geral dessa linha um equipamento central de medida de forma a ser possível a sua monitorização. No entanto, para a extrusora auxiliar as medições foram efectuadas com uma pinça amperimétrica e um fasímetro. Foram também efectuados ensaios onde foi avaliada a quantidade de material transformada, para isso foi utilizado um equipamento de pesagem, doseador gravimétrico aplicado nas extrusoras. As medições de temperatura para os cálculos das perdas térmicas da extrusora principal e para a caracterização dos materiais plásticos, foram efectuadas utilizando um termómetro digital. Foram efectuados ensaios de débito às extrusoras auxiliar e principal e foi estudada a variação do factor de potência em função da rotação do fuso. Na perspectiva do utilizador final a optimização para a utilização racional de energia está na redução de encargos da factura de energia eléctrica. Essa factura não depende só da quantidade mas também do modo temporal como se utiliza essa energia, principalmente a energia eléctrica, bastante dependente do período em que é consumida. Uma metodologia diferente no planeamento da produção, contemplando o fabrico dos cabos com maior custo específico nas horas de menor custo energético, implicaria uma redução dos custos específicos de 18,7% para o horário de verão e de 20,4% para o horário de inverno. Os materiais de revestimento utilizados (PE e PVC), influenciam directamente os custos energéticos, uma vez que o polietileno (PE) apresenta sempre valores de entalpia superiores (0,317 kWh/kg e 0,281 kWh/kg)) e necessita de temperaturas de trabalho mais elevadas do que o policloreto de vinilo (PVC) (0,141 kWh/kg e 0,124 kWh/kg). O consumo específico tendencialmente diminui à medida que aumenta a rotação do fuso, até se atingir o valor de rotação óptimo, a partir do qual esta tendência se inverte. O cosφ para as duas extrusoras em estudo, aumenta sempre com o aumento de rotação do fuso. Este estudo permitiu avaliar as condições óptimas no processo de revestimento dos cabos, de forma a minimizarmos os consumos energéticos. A redução de toda a espécie de desperdícios (sobre consumos, desperdício em purgas) é uma prioridade de gestão que alia também a eficácia à eficiência, e constitui uma ferramenta fundamental para assegurar o futuro da empresa. O valor médio lido para o factor de potência (0,38) da linha EP5, valor extremamente baixo e que vem associado à energia reactiva, além do factor económico que lhe está inerente, condiciona futuras ampliações. A forma de se corrigir o factor de potência é instalando uma bateria de condensadores de 500 kVAr. Considerando o novo sistema tarifário aplicado à energia reactiva, vamos ter um ganho de 36167,4 Euro/ano e o período de retorno de investimento é de 0,37 ano (4,5 meses). Esta medida implica também uma redução anual na quantidade de CO2 emitida de 6,5%. A quantificação das perdas térmicas é importante, pois só desta forma se podem definir modos de actuação de forma a aumentar a eficiência energética. Se não existir conhecimento profundo dos processos e metodologias correctas, não podem existir soluções eficientes, logo é importante medir antes de avançar com qualquer medida de gestão.

Modular high-current generator for electromagnetic forming with energy recovery

A 10 kJ electromagnetic forming (EMF) modulator with energy recovery based on two resonant power modules, each containing a 4.5 kV/30-kA silicon controlled rectifier, a 1.11-mF capacitor bank and an energy recovery circuit, working in parallel to allow a maximum actuator discharge current amplitude and rate of 50 kA and 2 kA/mu s was successfully developed and tested. It can be plugged in standard single phase 230 V/16 A mains socket and the circuit is able to recover up to 32% of its initial energy, reducing the charging time of conventional EMF systems by up to 68%.

Multilevel high-voltage pulse generation based on a new modular solid-state switch

This paper describes a modular solid-state switching cell derived from the Marx generator concept to be used in topologies for generating multilevel unipolar and bipolar high-voltage (HV) pulses into resistive loads. The switching modular cell comprises two ON/OFF semiconductors, a diode, and a capacitor. This cell can be stacked, being the capacitors charged in series and their voltages balanced in parallel. To balance each capacitor voltage without needing any parameter measurement, a vector decision diode algorithm is used in each cell to drive the two switches. Simulation and experimental results, for generating multilevel unipolar and bipolar HV pulses into resistive loads are presented.

Adapting remote labs to learning scenarios: case studies using VISIR and RemotElectLab

Remote laboratories are an emergent technological and pedagogical tool at all education levels, and their widespread use is an important part of their own improvement and evolution. This paper describes several issues encountered on laboratorial classes, on higher education courses, when using remote laboratories based on PXI systems, either using the VISIR system or an alternate in-house solution. Three main issues are presented and explained, all reported by teachers, that gave support to students' use of remote laboratories. The first issue deals with the need to allow students to select the actual place where an ammeter is to be inserted on electric circuits, even incorrectly, therefore emulating real-world difficulties. The second one deals with problems with timing when several measurements are required at short intervals, as in the discharge cycle of a capacitor. In addition, the last issue deals with the use of a multimeter in dc mode when reading ac values, a use that collides with the lab settings. All scenarios are presented and discussed, including the solution found for each case. The conclusion derived from the described work is that the remote laboratories area is an expanding field, where practical use leads to improvement and evolution of the available solutions, requiring a strict cooperation and information-sharing between all actors, i.e., developers, teachers, and students.

Automated design of microwave discrete tuning differential capacitance circuits in Si-integrated technologies

A genetic algorithm used to design radio-frequency binary-weighted differential switched capacitor arrays (RFDSCAs) is presented in this article. The algorithm provides a set of circuits all having the same maximum performance. This article also describes the design, implementation, and measurements results of a 0.25 lm BiCMOS 3-bit RFDSCA. The experimental results show that the circuit presents the expected performance up to 40 GHz. The similarity between the evolutionary solutions, circuit simulations, and measured results indicates that the genetic synthesis method is a very useful tool for designing optimum performance RFDSCAs.