Modelling the effect of defects and cracks in solar cells' performance using the d1MxP discrete model.

Renewable energies are increasingly playing an important role in the world's energy supply. Society demands new solutions to solve environmental issues caused by fossil fuels. The importance of photovoltaic technology has been increasing and consequently, the necessity to have more accurate models to characterise the performance of solar cells during their entire lifetime has rose as well. Performance problems may appear during devices' lifetimes associated with factors, such as weather conditions or faulty installation. Cracking might occur, leading to abrupt reductions on the produced power, quite difficult and expensive to fix. The I-V curves of a defected or cracked solar cell might not have the shape imposed by the usual models as 1M5P. In this article, cracked c-Si solar cells are modelled using a novel model: d1MxP. This model is based on the discretisation of the diode's response on models as 1M5P. Instead of imposing a shape and compute some parameters to fit it on experimental data, the proposed model connects every two points. The results suggest a better fit using the proposed model in comparison with the 1M5P, not only in the original curves, but also modelling cracked cells. As consequence of a better fitting, the computation of important figures of merit as maximum power point or fill factor, reveals to be more precise. It is concluded that the proposed model might characterise the performance of a solar cell, even cracked, which is a huge advance aiming the possibility of simulating complex problems during the cells' operation lifetime.

Modelling and Design of a Dual Depletion PIN Photodiode as Temperature Sensor.

Nowadays, optical systems play an important role in communications. Dual depletion PIN photodiodes are common devices that can operate in different optical bands, depending on the chosen semiconductors. However, since semiconductor properties vary with the surrounding conditions, some optical devices/systems can act as sensors. In this research work, a numerical model is implemented to analyze the frequency response of this kind of structure. It considers both transit time and capacitive effects, and can be applied to compute photodiode frequency response under nonuniform illumination. The InP-In0.53Ga0.47As photodiode is usually used to convert optical into electrical power at wavelengths around 1300 nm (O-band). This model is implemented considering an input frequency variation of up to 100 GHz. The focus of this research work was essentially the determination of the device's bandwidth from the computed spectra. This was performed at three different temperatures: 275 K, 300 K, and 325 K. The aim of this research work was to analyze if a InP-In0.53Ga0.47As photodiode can act as a temperature sensor, to detect temperature variations. Furthermore, the device dimensions were optimized, to obtain a temperature sensor. The optimized device, for a 6 V applied voltage and an active area of 500 µm2, had a total length of 2.536 µm, in which 53.95% corresponded to the absorption region. In these conditions, if the temperature increases 25 K from the room temperature, one should expect a bandwidth increase of 8.374 GHz, and if it decreases 25 K from that reference, the bandwidth should reduce by 3.620 GHz. This temperature sensor could be incorporated in common InP photonic integrated circuits, which are commonly used in telecommunications.

Nanostructures for Solar Energy Harvesting.

Renewable energy sources are becoming more and more essential to energy production as societies evolve toward a fossil-fuel-free world. Solar energy is one of the most abundant sources of green energy. Nanoantennas can be used to improve and enhance the absorption of light into a photovoltaic cell in order to generate more current. In this study, different nanoantenna structures are analysed in tandem with a silicon solar cell in an effort to improve its output. The nanoantennas studied are metallic aperture nanoantennas made up of either silver, aluminium, gold or copper. The three geometries compared are rectangular, circular and triangular. The maximum field enhancement obtained is for an aluminium rectangular nanoantenna of 50 nm thickness. Despite this, the geometry with more improvements compared with a basic silicon cell was the circle geometry with a 100 nm radius.

Improving the Performance of Paper-Based Dipole Antennas by Electromagnetic Flux Concentration.

One of the essential issues in modern advanced materials science is to design and manufacture flexible devices, in particular in the framework of the Internet of Things (IoT), to improve integration into applications. An antenna is an essential component of wireless communication modules and, in addition to flexibility, compact dimensions, printability, low cost, and environmentally friendlier production strategies, also represent relevant functional challenges. Concerning the antenna's performance, the optimization of the reflection coefficient and maximum range remain the key goals. In this context, this work reports on screen-printed paper@Ag-based antennas and optimizes their functional properties, with improvements in the reflection coefficient (S11) from -8 to -56 dB and maximum transmission range from 208 to 256 m, with the introduction of a PVA-Fe3O4@Ag magnetoactive layer into the antenna's structure. The incorporated magnetic nanostructures allow the optimization of the functional features of antennas with possible applications ranging from broadband arrays to portable wireless devices. In parallel, the use of printing technologies and sustainable materials represents a step toward more sustainable electronics.

Electroactive functional microenvironments from bioactive polymers: A new strategy to address cancer.

The present work reports on a new approach based on electroactive microenvironments to mitigate skeletal muscle cancer. For that, piezoelectric films based on poly(vinylidene fluoride) have been applied to evaluate the influence of mechano- and/or electrical stimuli on rhabdomyosarcoma (RMS) proliferation. Human embryonal rhabdomyosarcoma (RD) cells were cultured on PVDF pristine films with different surface charge (non-poled, poled+ and poled-) and magnetic composites (10% and 20% Fe3O4, and 20% CFO filler content) to allow magneto-mechanical and magnetoelectrical stimulation films. Electrospun PVDF pristine (oriented and randomly) and magnetic (10% Fe3O4) fiber mats were also evaluated to take into consideration the morphology effect on cell response. It was found that the mechanical stimuli enhance RMS proliferation whereas the mechano-electrical decreases it. It was also verified that the RD cells proliferate better on randomly oriented fibers, whereas myoblast cells do it better in oriented ones. The obtained results confirm that electroactive microenvironments can be used to develop novel and effective approaches to deal with RMS cancer, that can be extrapolated to others cancer types.

Sustainable plant polyesters as substrates for optical gas sensors.

The fast and non-invasive detection of odors and volatile organic compounds (VOCs) by gas sensors and electronic noses is a growing field of interest, mostly due to a large scope of potential applications. Additional drivers for the expansion of the field include the development of alternative and sustainable sensing materials. The discovery that isolated cross-linked polymeric structures of suberin spontaneously self-assemble as a film inspired us to develop new sensing composite materials consisting of suberin and a liquid crystal (LC). Due to their stimuli-responsive and optically active nature, liquid crystals are interesting probes in gas sensing. Herein, we report the isolation and the chemical characterization of two suberin types (from cork and from potato peels) resorting to analyses of gas chromatography-mass spectrometry (GC-MS), solution nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS). The collected data highlighted their compositional and structural differences. Cork suberin showed a higher proportion of longer aliphatic constituents and is more esterified than potato suberin. Accordingly, when casted it formed films with larger surface irregularities and a higher C/O ratio. When either type of suberin was combined with the liquid crystal 5CB, the ensuing hybrid materials showed distinctive morphological and sensing properties towards a set of 12 VOCs (comprising heptane, hexane, chloroform, toluene, dichlormethane, diethylether, ethyl acetate, acetonitrile, acetone, ethanol, methanol, and acetic acid). The optical responses generated by the materials are reversible and reproducible, showing stability for 3 weeks. The individual VOC-sensing responses of the two hybrid materials are discussed taking as basis the chemistry of each suberin type. A support vector machines (SVM) algorithm based on the features of the optical responses was implemented to assess the VOC identification ability of the materials, revealing that the two distinct suberin-based sensors complement each other, since they selectively identify distinct VOCs or VOC groups. It is expected that such new environmentally-friendly gas sensing materials derived from natural diversity can be combined in arrays to enlarge selectivity and sensing capacity.

Physically Active Bioreactors for Tissue Engineering Applications.

Tissue engineering (TE) is a strongly expanding research area. TE approaches require biocompatible scaffolds, cells, and different applied stimuli, which altogether mimic the natural tissue microenvironment. Also, the extracellular matrix serves as a structural base for cells and as a source of growth factors and biophysical cues. The 3D characteristics of the microenvironment is one of the most recognized key factors for obtaining specific cell responses in vivo, being the physical cues increasingly investigated. Supporting those advances is the progress of smart and multifunctional materials design, whose properties improve the cell behavior control through the possibility of providing specific chemical and physical stimuli to the cellular environment. In this sense, a varying set of bioreactors that properly stimulate those materials and cells in vitro, creating an appropriate biomimetic microenvironment, is developed to obtain active bioreactors. This review provides a comprehensive overview on the important microenvironments of different cells and tissues, the smart materials type used for providing such microenvironments and the specific bioreactor technologies that allow subjecting the cells/tissues to the required biomimetic biochemical and biophysical cues. Further, it is shown that microfluidic bioreactors represent a growing and interesting field that hold great promise for achieving suitable TE strategies.

Polymer-based actuators: back to the future.

Polymer-based actuators play a key role in the area of smart materials and devices, and for this reason different polymer-based actuators have appeared in recent years and are implemented in a broad range of fields, including biomedical, optical or electronics, among others. Although it is possible to find more types, they are mainly classified into two main groups according to their different working principles: electromechanical - with electrical to mechanical energy conversion - and magnetomechanical - with magnetic to mechanical energy conversion. The present work provides a comprehensive and critical review of the recent studies in this field. The operating principles, some representative designs, performance analyses and practical applications will be presented. The future development perspectives of this interesting field will be also discussed. Thus, the present work provides a comprehensive understanding of the effects reported in the past, introduces solutions to the present limitations and, back to the future, serves as a useful guidance for the design of new polymer-based actuators aiming to improve their output performances.

The molecular structure and multifunctionality of the cryptic plant polymer suberin.

Suberin, a plant polyester, consists of polyfunctional long-chain fatty acids and glycerol and is an intriguing candidate as a novel antimicrobial material. We purified suberin from cork using ionic-liquid catalysis during which the glycerol bonds that ensure the polymeric nature of suberin remained intact or were only partially cleaved-yielding the closest to a native configuration reported to date. The chemistry of suberin, both in situ (in cryogenically ground cork) and ex situ (ionic-liquid extracted), was elucidated using high-resolution one- and two-dimensional solution-state NMR analyses. Centrifugation was used to isolate suberin particles of distinct densities and their monomeric composition, assembly, and bactericidal effect, inter alia, were assessed. Analysis of the molecular structure of suberin revealed the relative abundance of linear aliphatic vs. acylglycerol esters, comprising all acylglycerol configurations and the amounts of total carbonyls (C[bond, double bond]O), free acid end groups (COOH), OH aliphatics, and OH aromatics. Suberin centrifuged fractions revealed generic physiochemical properties and monomeric composition â€‹and self-assemble into polygonal structures that display distinct degrees of compactness when lyophilized. Suberin particles-suberinsomes-display bactericidal activity against major human pathogenic bacteria. Fingerprinting the multifunctionality of complex (plant) polyesters such as suberin allows for the identification of novel polymer assemblies with significant value-added properties.

Proving the suitability of magnetoelectric stimuli for tissue engineering applications.

A novel approach for tissue engineering applications based on the use of magnetoelectric materials is presented. This work proves that magnetoelectric Terfenol-D/poly(vinylidene fluoride-co-trifluoroethylene) composites are able to provide mechanical and electrical stimuli to MC3T3-E1 pre-osteoblast cells and that those stimuli can be remotely triggered by an applied magnetic field. Cell proliferation is enhanced up to ≈ 25% when cells are cultured under mechanical (up to 110 ppm) and electrical stimulation (up to 0.115 mV), showing that magnetoelectric cell stimulation is a novel and suitable approach for tissue engineering allowing magnetic, mechanical and electrical stimuli.

Design and validation of a biomechanical bioreactor for cartilage tissue culture.

Specific tissues, such as cartilage, undergo mechanical solicitation under their normal performance in human body. In this sense, it seems necessary that proper tissue engineering strategies of these tissues should incorporate mechanical solicitations during cell culture, in order to properly evaluate the influence of the mechanical stimulus. This work reports on a user-friendly bioreactor suitable for applying controlled mechanical stimulation--amplitude and frequency--to three-dimensional scaffolds. Its design and main components are described, as well as its operation characteristics. The modular design allows easy cleaning and operating under laminar hood. Different protocols for the sterilization of the hermetic enclosure are tested and ensure lack of observable contaminations, complying with the requirements to be used for cell culture. The cell viability study was performed with KUM5 cells.

Diferentes níveis de incorporação de farinha de resíduos de jundiás (Rhamdiaquelen) cultivados na dieta / Different levels of jundiá waste meal in the diet

O estudo foi desenvolvido no Laboratório de Piscicultura do Departamento de Zootecnia da Universidade Federal de Santa Maria, com duração de oito semanas, de abril a junho de 2011. O objetivo foi definir o melhor nível de incorporação do resíduo de peixes na alimentação de juvenis de jundiá, em sistema de recirculação d'água, utilizando-se 450 alevinos de jundiás, com peso médio inicial de 7,2±0,27g. Foram testadas cinco diferentes dietas, em três repetições, com níveis diferentes (0; 3,75; 7,5; 15; e 30 por cento) de incorporação de farinha de carcaça de jundiás com vísceras (FCJCV). As dietas continham, aproximadamente, 37 por cento de PB e 3200kcal de EM/kg de dieta. Foram coletados dados de ganho em peso diário, sobrevivência, fator de condição, taxa de crescimento específico, conversão alimentar aparente, rendimento de carcaça, taxa de eficiência proteica e deposição de proteína e lipídio corporal. O maior ganho de peso foi para o nível 30 por cento de inclusão de FCJCV, com peso final de 45,47g e ganho em peso diário de 0,68g/dia. A dieta com nível de 30% de inclusão de FCJCV apresentou melhores valores para taxa de crescimento específico (3,34 por cento/dia), conversão alimentar aparente (1,05: 1), biomassa final 1.105,45g, deposição proteica corporal (64,9mg/dia), taxa de eficiência proteica (1,9) e coeficiente de retenção proteica (1,96 por cento). Concluiu-se que a utilização de farinha de resíduos de processamento de jundiá no nível de 30% de inclusão na dieta foi a que apresentou maior eficiência no desenvolvimento de juvenis de jundiá...

The study was carried out at the Fish Farming Laboratory of the Animal Science Department, Federal University of Santa Maria, during 8 weeks, from April to June 2011. The objective of this study was to define the best level of incorporation of waste in food fish of juvenile Jundiá in water recirculation system using 450 fingerlings of jundiá with initial average weight of 7.2±0.27g. We tested 5 different diets in three repetitions with different levels of incorporation of carcasse jundiá with viscera meal (FCJCV) (0, 3.75, 7.5, 15, and 30 percent). The diets contained 37 percent CP and 3200kcal/kg of ME. Data were collected from daily weight gain, survival, condition factor, specific growth rate, feed conversion, carcass yield, protein efficiency ratio and deposition of body protein and lipid. The weight gain was greater with the inclusion of 30 percent FCJCV with final weight of 45.47g and daily weight gain of 0.68g/day. The diet with inclusion of 30 percent FCJCV showed better values for specific growth rate (3.34 percent/day), feed conversion ratio (1.05: 1), final biomass (1105.45g), body protein deposition (64.9mg/day), protein efficiency ratio (1.9) and protein retention coefficient (1.96 percent). In conclusion, the use of processing waste meal of jundiá in the level of 30 percent in the diet showed the highest efficiency in the development of juvenile jundiá...

Design and development of a prototype electrotherapy device.

This article describes a complete prototype system that can be used in electrotherapy treatments, that is, in medical treatments involving electric currents. The system is composed of two main blocks: the master and the slave. The Master block, whose main component is a CPU, controls the user interface. The Slave block, which is composed of a microcontroller and a wave generator, produces the appropriated voltages and currents compatible with the desired treatment. The whole system is powered by a 12 V power supply and the output signal voltage ranges between -100 V and 100 V. Despite the prototype being able of performing all the electrotherapy treatments in the low-medium frequency ranges, it was tested in aesthetic mesotherapy, namely in anticellulite, located anticellulite, antistretch, and antiflaccidity. In these treatments, the output signal is composed of an overlap of two frequencies: the first one is selected in the range of 1.2 kHz - 1.8 kHz and the second in the range of 0.07 Hz - 2 Hz. The system was tested in a clinical environment with real patients. It showed good results both in effectiveness of treatments and in terms of pain suffered by the patients.

Fontes energéticas vegetais para juvenis de jundiá e carpa / Plant-energy sources for jundiá and carp juvenile

Para avaliar o desempenho, o metabolismo e a composição corporal de juvenis de jundiá (Rhamdia quelen) e de carpa húngara (Cyprinus carpio) alimentados com fontes energéticas vegetais, foi conduzido experimento de 60 dias. Três dietas compostas por aveia descascada, farelo de arroz desengordurado estabilizado (FADE) ou por farelo de trigo e milho (dieta-controle) foram ofertadas três vezes ao dia a 360 juvenis de jundiá (5,59±0,06g) ou de carpa húngara (5,82±0,14g) distribuídos em 18 tanques (280L), totalizando nove tanques por espécie. Não foram observadas diferenças significativas no desempenho das espécies estudadas. Em relação aos parâmetros metabólicos, as menores concentrações séricas de colesterol total no jundiá foram verificadas nas dietas com aveia (214,49mg/dL) e FADE (216,3mg/dL), enquanto para a carpa húngara as menores concentrações observadas foram nos peixes alimentados com FADE (222,54mg/dL). Quanto à composição centesimal, os valores de gordura no filé foram menores nos jundiás dos tratamentos controle (3,76%) e aveia (3,95%). A inclusão de aveia proporcionou menor deposição de gordura corporal em ambas as espécies. Conclui-se que 20% de aveia descascada ou de farelo de arroz desengordurado podem ser incluídos na dieta de juvenis de jundiá e de carpa húngara sem prejuízos para o crescimento.

In order to evaluate the performance, metabolism and body composition of jundiá (Rhamdia quelen) and common carp (Cyprinus carpio) juvenile fed with plant-energy sources, the experiment was conducted during 60 days. Three diets composed of husked oats, defatted rice bran stabilized (FADE) or wheat bran and corn (control diet) were provided three times daily to 360 jundiá juveniles (5.59±0.06g) or common carp (5.82±0.14g) distributed into 18 tanks (280L), totaling nine tanks per species. There were no significant differences in performance parameters in both species. For metabolic parameters, the lowest serum levels of total cholesterol in jundiá were observed in diets containing oats (214,49mg/dL) and FADE (216,3mg/dL), while for the common carp the lowest levels were observed in fish fed FADE (222,54mg/dL). As for the composition, the fat in the fillet was lower in the jundiá from control (3,76%) and oats (3,95%) treatments, providing the lowest body fat deposition in both species. The inclusion of oats showed lower body fat deposition in both species. It is concluded that the inclusion of 20% stabilized husked oats or defatted rice bran in the diet of jundiá and common carp juvenile does no harm to growth.

Crescimento de juvenis de jundiá (Rhamdia quelen) com diferentes proporções de amilose: amilopectina na dieta / Growth of jundiá juveniles (Rhamdia quelen) with different proportions of amylose:amylopectin in diet

Crescimento e características de carcaça do jundiá (Rhamdia quelen) foram avaliados após 60 dias de alimentação com diferentes proporções de amilose:amilopectina na dieta. Foram criados 240 peixes (peso inicial de 34,3±4,3g) em sistema de recirculação de água constituído de 12 unidades experimentais de 280L. Foram testadas três dietas com as proporções amilose:amilopectina de: T417 = com 26 por cento de amilose, T416 = com 16 por cento de amilose e TMOCHI = com 0 por cento de amilose. Os peixes foram alimentados duas vezes por dia, às 8h e 30min e às 16 horas. A cada 15 dias, foram feitas biometrias para ajuste da quantidade de alimento ofertado. A proporção amilose:amilopectina no amido das dietas não influenciou o crescimento, os rendimentos de carcaça e a composição corporal dos peixes. Conclui-se que o jundiá tem potencial para utilizar fontes de amido compostas por até 26 por cento de amilose sem alterar a digestibilidade dos nutrientes e a deposição de gordura.

The growth and carcass traits of jundiá (Rhamdia quelen) after 60 days being fed with different amylose:amylopectin ratio in diet were evaluated. Two hundred and forty fish (initial weight of 34.3±4.3g) were raised in water re-use system with 12 units of 280L. Three diets were tested with amylose:amylopectin ratios: T417 = 26 percent amylose, T416 = 16 percent amylose and TMOCHI = 0 percent amylose. The fish were fed twice a day at 8:30 and 16:00h. Every 15 days the amount of food offered was ajusted. The amylose:amylopectin ratio in the starch of the diet did not affect growth, carcass and body composition of fish. This demonstrates that the jundiá has the potential to use starchy sources consisting of up to 26 percent amylose without altering the digestibility of nutrients and fat deposition.

Teores de proteína bruta em dietas práticas para juvenis de carpa capim / Crude protein levels in practical diets for grass carp juveniles

Avaliou-se a resposta de juvenis de carpa capim (Ctenopharyngodon idella) à inclusão de proteína bruta (PB) em dietas práticas, em um experimento com 120 juvenis e 80 dias de duração. As dietas eram compostas por farinha de carne suína, farelo de soja, milho e farelo de trigo com 22, 30, 36 ou 44 por cento de PB. Dez juvenis (153,0±1,5g) por tanque (850L) foram alimentados duas vezes ao dia (3 por cento da biomassa). Foi observado efeito linear positivo da PB para peso final, ganho em peso, taxa de crescimento específico, rendimento de carcaça e filé, coeficiente de retenção proteica, taxa de eficiência proteica, deposição de gordura e proteína e hematócrito. O mesmo efeito também foi observado para triglicerídeos e colesterol total no sangue, indicando que a proteína da dieta foi utilizada como fonte energética. Conversão alimentar aparente e gordura no peixe inteiro apresentaram efeito quadrático, com pontos de máxima em 40,6 e 37,1 por cento de PB, respectivamente. Pode-se concluir que a porcentagem mínima de PB para a carpa capim na fase de recria foi de 44 por cento e que a variação da proteína da dieta promoveu alterações no metabolismo dos juvenis de carpa capim, refletidos nos parâmetros sanguíneos e de carcaça.

The response of grass carp (Ctenopharyngodon idella) juveniles to crude protein (CP) levels in practical diets was evaluated in an experiment with 120 juveniles and 80 days of feeding. The diets containing porcine meat meal, soybean meal, corn and wheat meal, with 22, 30, 36, or 44 percent CP. Ten juveniles (153.0±1.5 g) per tank (850L) were fed twice daily with pelleted feed (3 percent of biomass). Linear effect of CP on final weight, weight gain, specific growth rate, carcass and fillet yield, coefficient of protein retention, protein efficiency rate, deposition of fat and protein, and hematocrit were observed. It was also observed effect on triglycerides and total cholesterol in blood, indicating that dietary protein was being used as energy source. Feed conversion ratio and fat content in whole fish showed quadratic effect, with maximum points at 40.6 and 37.1 percent CP, respectively. The best CP content for grass carp in growing phase was 44 percent, and the variation of protein content in diet changed the metabolism of grass carp juveniles, reflected in blood and carcass parameters.

Influência do tau na tomada de decisão no basquetebol / No disponible

Padrões de comportamento decisional emergem constrangidos pela informação contextual de interacções atleta-ambiente (e.g. um-contra-um) através de simetria e quebras de simetria (Araújo et al., 2006; Davids et al., 2006). O presente artigo pretende demonstrar como a Teoria Geral do Tau (Lee, 1998) poderá promover o estudo e compreensão do comportamento decisional de jogadores de basquetebol (AU)

Two-dimensional fluorometry coupled with artificial neural networks: a novel method for on-line monitoring of complex biological processes.

The use of two-dimensional scanning fluorometry as an on-line, noninvasive, in situ bioreactor monitoring technique is extended to complex bioprocesses using mixed cultures, with particular attention to biofilm systems. Using the example of spectra subtraction, it is demonstrated that established methods for fluorescence data analysis have a limited capability of utilizing overall fluorometric information. Artificial neural networks (ANNs) are introduced as a novel nonlinear and nonmechanistic technique for interpreting the highly complex fluorescence maps. It is shown that ANNs are able to infer process performance parameters in a pattern recognition approach, based on the entire fluorescence "fingerprint" of the biological system. The studies were carried out using an extractive membrane bioreactor (EMB) for the degradation of chlorinated organic compounds, operating with mixed cultures. Model pollutants em- ployed were 1,2-dichloroethane, 3-chloro-4-methylaniline, and p-toluidine.

[A histological analysis of the changes experimentally induced by cadmium in cardiac muscle tissue by a computerized method of image analysis]. / Análise histológica de alterações induzidas experimentalmente por cádmio no tecido muscular cardíaco através de método computadorizado de análise de imagens.

OBJECTIVE: To study the distribution of myocardial structural elements in a univentricular experimental model (Halobatrachus didactylus) and the changes induced by acute exposure to a sublethal concentrations of cadmium. DESIGN: 15 specimens of H. didactylus (marine teleost) were divided in three groups: CTRL: the control group, the fish were injected with a saline solution; 24 H: 1 mg/kg of cadmium chloride was injected and fish were sacrificed after 1 day post injection; 7 D: fish where subjected to the same cadmium concentration and sacrificed after 7 days post injection. INTERVENTIONS: Histological sections (5 microns) of ventricle were coloured by PicroSirius method and used to determine the fraction area occupied by the several myocardium structural elements, using specific software Optimas Bioscan 5.2. MEASUREMENTS AND RESULTS: The different structural elements of H. didactylus myocardium displayed in different ways and its distribution along the ventricular wall remained unchanged on exposure to cadmium. The structural elements of H. didactylus myocardium showed a characteristic pattern: collagen type I revealed a heterogeneous distribution, with fractional area values greater in epicardial and endocardial layers; collagen type III, has a homogeneous distribution with the myocardial wall thickness with lesser fractional area values than collagen I; cardiac muscle tissue showed a tendency to occupy a greater fractional area in the epicardial-endocardial region. Cadmium toxicity resulted in an increase in the fractional area occupied by muscle tissue to the detriment of the area occupied by the intertrabecular spaces (lacunae), with no alterations in the other structural components. CONCLUSIONS: On our H. didactylus fish model, cadmium may have induced a myocardial edema which resulted in an increase in the fractional area occupied by muscle tissue, with no alterations in other structural components of the myocardium or in the relative ventricular mass.