IBPOWER Project, Intermediate band materials and solar cells for photovoltaics with high efficiency and reduced cost

IBPOWER is a Project awarded under the 7th European Framework Programme that aims to advance research on intermediate band solar cells (IBSCs). These are solar cells conceived to absorb below bandgap energy photons by means of an electronic energy band that is located within the semiconductor bandgap, whilst producing photocurrent with output voltage still limited by the total semiconductor bandgap. IBPOWER employs two basic strategies for implementing the IBSC concept. The first is based on the use of quantum dots, the IB arising from the confined energy levels of the electrons in the dots. Quantum dots have led to devices that demonstrate the physical operation principles of the IB concept and have allowed identification of the problems to be solved to achieve actual high efficiencies. The second approach is based on the creation of bulk intermediate band materials by the insertion of an appropriate impurity into a bulk semiconductor. Under this approach it is expected that, when inserted at high densities, these impurities will find it difficult to capture electrons by producing a breathing mode and will cease behaving as non-radiative recombination centres. Towards this end the following systems are being investigated: a) Mn: In1-xGax N; b) transition metals in GaAs and c) thin films.

A cost-effective high-throughput digital system for observation and acquisition of animal behavioral data

We have designed and implemented a low-cost digital system using closed-circuit television cameras coupled to a digital acquisition system for the recording of in vivo behavioral data in rodents and for allowing observation and recording of more than 10 animals simultaneously at a reduced cost, as compared with commercially available solutions. This system has been validated using two experimental rodent models: one involving chemically induced seizures and one assessing appetite and feeding. We present observational results showing comparable or improved levels of accuracy and observer consistency between this new system and traditional methods in these experimental models, discuss advantages of the presented system over conventional analog systems and commercially available digital systems, and propose possible extensions to the system and applications to nonrodent studies.

A cost-effective high-throughput digital system for observation and acquisition of animal behavioral data

We have designed and implemented a low-cost digital system using closed-circuit television cameras coupled to a digital acquisition system for the recording of in vivo behavioral data in rodents and for allowing observation and recording of more than 10 animals simultaneously at a reduced cost, as compared with commercially available solutions. This system has been validated using two experimental rodent models: one involving chemically induced seizures and one assessing appetite and feeding. We present observational results showing comparable or improved levels of accuracy and observer consistency between this new system and traditional methods in these experimental models, discuss advantages of the presented system over conventional analog systems and commercially available digital systems, and propose possible extensions to the system and applications to non-rodent studies.

A Novel Cost-Efficient On-Line Intermediate Waveband-Switching Scheme in WDM Mesh Networks

Waveband switching (WBS) is an important technique to save switching and transmission cost in wavelength -division multiplexed (WDM) optical networks. A cost-efficient WBS scheme would enable network carriers to increase the network throughput (revenue) while achieving significant cost savings. We identify the critical factors that determine the WBS network throughput and switching cost and propose a novel intermediate waveband switching (IT-WBS) algorithm, called the minimizing-weighted-cost (MWC) algorithm. The MWC algorithm defines a cost for each candidate route of a call. By selecting the route with the smallest weighted cost, MWC balances between minimizing the call blocking probability and minimizing the network switching cost. Our simulations show that MWC outperforms other wavelength/waveband switching algorithms and can enhance the network throughput at a reduced cost.

Convergence analysis and validation of low cost distance metrics for computational cost reduction of the Iterative Closest Point algorithm

The Iterative Closest Point algorithm (ICP) is commonly used in engineering applications to solve the rigid registration problem of partially overlapped point sets which are pre-aligned with a coarse estimate of their relative positions. This iterative algorithm is applied in many areas such as the medicine for volumetric reconstruction of tomography data, in robotics to reconstruct surfaces or scenes using range sensor information, in industrial systems for quality control of manufactured objects or even in biology to study the structure and folding of proteins. One of the algorithm’s main problems is its high computational complexity (quadratic in the number of points with the non-optimized original variant) in a context where high density point sets, acquired by high resolution scanners, are processed. Many variants have been proposed in the literature whose goal is the performance improvement either by reducing the number of points or the required iterations or even enhancing the complexity of the most expensive phase: the closest neighbor search. In spite of decreasing its complexity, some of the variants tend to have a negative impact on the final registration precision or the convergence domain thus limiting the possible application scenarios. The goal of this work is the improvement of the algorithm’s computational cost so that a wider range of computationally demanding problems from among the ones described before can be addressed. For that purpose, an experimental and mathematical convergence analysis and validation of point-to-point distance metrics has been performed taking into account those distances with lower computational cost than the Euclidean one, which is used as the de facto standard for the algorithm’s implementations in the literature. In that analysis, the functioning of the algorithm in diverse topological spaces, characterized by different metrics, has been studied to check the convergence, efficacy and cost of the method in order to determine the one which offers the best results. Given that the distance calculation represents a significant part of the whole set of computations performed by the algorithm, it is expected that any reduction of that operation affects significantly and positively the overall performance of the method. As a result, a performance improvement has been achieved by the application of those reduced cost metrics whose quality in terms of convergence and error has been analyzed and validated experimentally as comparable with respect to the Euclidean distance using a heterogeneous set of objects, scenarios and initial situations.

Comparative effects of ageing and dementia of the Alzheimer type on orientation of visual attention

Age-related changes and the effects of dementia of the Alzheimer type (DAT) were investigated during a visual orienting attention task in which attention was pre-cued to one or other hemifields. Central cues were either valid, neutral, invalid or NoGo (inhibitory). The response time cost-benefit analysis showed a decreased benefit after valid cueing in the old compared with the young group with no change in the cost of invalid cueing. The older group were also slower over all cue types. These results suggest there is an age-related reduced ability to covertly orient attention in a visual hemifield before target onset. In contrast, the DAT group showed an increased response time benefit and showed a trend for a decreased cost in response time compared with controls. This was due to slowest response times after neutral cues. They also made significantly more response errors particularly following neutral cueing, and were less able to inhibit responses on NoGo trials than controls. The increased benefit and reduced cost found in the DAT group was interpreted as an impairment in dividing attention between left and right target locations.

Concepção e instalação de tabelas multifunções para recintos desportivos cobertos

Mestrado em Engenharia Electrotécnica – Sistemas Eléctricos de Energia

Electroanalytical study of fluvoxamine

Fluvoxamine (FVX) can be reduced at a mercury- drop electrode, with a maximum peak current intensity being obtained at a potential of -0.7 V vs. Ag/ AgCl, in an aqueous electrolyte solution of pH 2. The compound was determined in a pharmaceutical product and in spiked human serum by square-wave adsorptivestripping voltammetry (SWAdSV) after accumulation at the electrode surface, under batch conditions. Because the presence of dissolved oxygen did not interfere significantly with the analysis, it was also possible to determine FVX in the pharmaceutical product by use of a flow-injection analysis (FIA) system with SWAdSV detection. The methods developed were validated and successfully applied to the quantification of FVX in a pharmaceutical product. Recoveries between 76 and 89% were obtained in serum analysis. The FIA– SWAdSV method enabled analysis of up to 120 samples per hour at reduced cost, implying the possibility of competing with the chromatographic methods usually used for this analysis.

Cancer theranostics: multifunctional gold nanoparticles for diagnostics and therapy

Doctorate in Biology, Specialty in Biotechnology

Estudo, projeto e desenvolvimento de uma máquina para montar e vincar sacos de papel

Dissertação de mestrado integrado em Engenharia Mecânica

Energy expenditure before and during energy restriction in obese patients.

Twenty-four hour energy expenditure (24 EE), resting metabolic rate (RMR), spontaneous physical activity and body composition were determined in 7 obese patients (5 females, 2 males, 174 +/- 9% IBW, 38 +/- 2% fat mass) on 2 different occasions: before weight reduction, and after 10 to 16 weeks on a hypocaloric diet as outpatients, the recommended energy intake varying from 3500 to 4700 kJ/day depending on the subject. Mean body weight loss was 12.6 +/- 1.9 kg, ie 13% of initial body weight, 72% being fat. Twenty-four hour energy expenditure (24 EE) was measured in a respiration chamber with all the subjects receiving 10418 kJ/d before weight reduction and an average of 3360 +/- 205 kJ/d while on the diet. When expressed in absolute values, both 24 EE and RMR decreased during the hypocaloric diet from 9819 +/- 442 to 8229 +/- 444 and from 7262 +/- 583 to 6591 +/- 547 kJ/d respectively. On the basis of fat-free-mass (FFM), 24 EE decreased from 168 +/- 6 to 148 +/- 5 kJ/kg FFM/d whereas RMR was unchanged (approximately 120 kJ/kg FFM/d). Approximately one half of the 24 EE reduction (1590 kJ/d) was accounted for by a decrease in RMR, the latter being mainly accounted for by a reduction in FFM. Most of the remaining decline in 24 EE can be explained by a decreased thermic effect of food, and by the reduced cost of physical activity mainly due to a lower body weight. Therefore, there seems little reason to evoke additional mechanisms to explain the decline in energy expenditure during dieting.

Spare non-occupational HIV post-exposure prophylaxis by active contacting and testing of the source person.

OBJECTIVE: HIV-1 post-exposure prophylaxis (PEP) is frequently prescribed after exposure to source persons with an undetermined HIV serostatus. To reduce unnecessary use of PEP, we implemented a policy including active contacting of source persons and the availability of free, anonymous HIV testing ('PEP policy'). METHODS: All consultations for potential non-occupational HIV exposures i.e. outside the medical environment) were prospectively recorded. The impact of the PEP policy on PEP prescription and costs was analysed and modelled. RESULTS: Among 146 putative exposures, 47 involved a source person already known to be HIV positive and 23 had no indication for PEP. The remaining 76 exposures involved a source person of unknown HIV serostatus. Of 33 (43.4%) exposures for which the source person could be contacted and tested, PEP was avoided in 24 (72.7%), initiated and discontinued in seven (21.2%), and prescribed and completed in two (6.1%). In contrast, of 43 (56.6%) exposures for which the source person could not be tested, PEP was prescribed in 35 (81.4%), P < 0.001. Upon modelling, the PEP policy allowed a 31% reduction of cost for management of exposures to source persons of unknown HIV serostatus. The policy was cost-saving for HIV prevalence of up to 70% in the source population. The availability of all the source persons for testing would have reduced cost by 64%. CONCLUSION: In the management of non-occupational HIV exposures, active contacting and free, anonymous testing of source persons proved feasible. This policy resulted in a decrease in prescription of PEP, proved to be cost-saving, and presumably helped to avoid unnecessary toxicity and psychological stress.

Raspberry Pi: a 35-dollar device for viewing DICOM images

Raspberry Pi is a low-cost computer created with educational purposes. It uses Linux and, most of times, freeware applications, particularly a software for viewing DICOM images. With an external monitor, the supported resolution (1920 × 1200 pixels) allows for the set up of simple viewing workstations at a reduced cost.

Determinação de fósforo orgânico em águas de produção petrolífera por ICP- AES e ICP- MS após pré-concentração em coluna de sílica-C18

Results on the optimization of analytical methods for the determination of phosphorus in phosphino-polycarboxylate (PPCA), used frequently as scale inhibitor during oil production, by ICP-AES and ICP-MS are presented. Due to the complex matrix of production waters (brines) and their high concentration in inorganic phosphorus, the separation of organic phosphorus prior to its determination is necessary. In this work, minicolumns of silica immobilized C18 were used. Optimization of the separation step resulted in the following working conditions: (1) prewashing of the column with methanol (80% v/v); (2) use of a flow rate of 5 mL/min and 10 mL/min, respectively, for the preconditioning step and for percolation of the water sample; (3) final elution of organic phosphorus with 7 mL of buffer of H3BO3/NaOH (0.05 M, pH 9) with a flow rate of 1 mL/min. Sample detection limits (3s) for different combinations of nebulizers and spectrometric methods, based on 10 mL water aliquots, are: ICP-AES -Cross flow (47 mg/L) and Ultrasonic (18 mug/L); ICP-MS -Cross flow (1.2 mug/L), Cyclonic (0.7 mug/L) and Ultrasonic (0.5 mug/L). Typical recoveries of organic phosphorus are between 90 and 95% and the repeatability of the whole procedure is better than 10%. The developed methodology was applied successfully to samples from the oil-well NA 46, platform PNA 2, Campos basin, Brazil. Assessment of the PPCA inhibitor was possible at lower concentrations than achieved by current analytical methods, resulting in benefits such as reduced cost of chemicals, postponed oil production and lower environmental impacts.

Impact properties of glass/plant fibre hybrid laminates

The use of plants fibre reinforced composites has continuously increased during recent years. Their low density, higher environmental friendliness, and reduced cost proved particularly attractive for low-tech applications e.g., in building, automotive and leisure time industry. However, a major limitation to the use of these materials in structural components is unsatisfactory impact performance. An intermediate approach, the production of glass/ plant fibre hybrid laminates, has also been explored, trying to obtain materials with sufficient impact properties, whilst retaining a reduced cost and a substantial environmental gain. A survey is given on some aspects, crucial for the use of glass/plant fibre hybrid laminates in structural components: performance of hybrids when subjected to impact testing; the effect of laminate configuration, manufacturing procedure and fibre treatment on impact properties of the composite. Finally, indications are provided for a suitable selection of plant fibres with minimal extraction damage and sufficient toughness, for introduction in an impact-resistant glass/plant fibre hybrid laminate.