Optical demultiplexer device operating in the visible spectrum

In this paper, we present results on the use of multilayered a-SiC:H heterostructures as a device for wavelength-division demultiplexing of optical signals. These devices are useful in optical communications applications that use the wavelength division multiplexing technique to encode multiple signals into the same transmission medium. The device is composed of two stacked p-i-n photodiodes, both optimized for the selective collection of photo generated carriers. Band gap engineering was used to adjust the photogeneration and recombination rate profiles of the intrinsic absorber regions of each photodiode to short and long wavelength absorption in the visible spectrum. The photocurrent signal using different input optical channels was analyzed at reverse and forward bias and under steady state illumination. A demux algorithm based on the voltage controlled sensitivity of the device was proposed and tested. An electrical model of the WDM device is presented and supported by the solution of the respective circuit equations

Preparation and Characterization of a-SiC:H Absorber Layer for Semi-transparent Solar Cells

AbstractThis paper reports on device-quality silicon-carbon alloy (a-SiC:H) application as an absorber material in semi-transparent solar cells. Films with an optical bandgap ranging from 2 to 2.3 eV were prepared by plasma enhanced chemical vapour deposition (PECVD). The n-i-p structures with undoped SiC:H layers deposited under the same experimental conditions were also fabricated and characterized. The optimized devices showed forward current-voltage characteristics with a diode ideality factor in the range from 1.4 to 1.8, and an open circuit voltage up to 0.92 V. The density of deep defect states in a SiC:H was estimated from the transient current measurements and correlated with the optical bandgap

Efeitos do treinamento aeróbico em camundongos ateroscleróticos

A doença aterosclerótica é caracterizada por um processo inflamatório crônico que, por sua vez, pode acelerar a senescência de células vasculares e agravar a instalação de placas. O exercício aeróbico moderado melhora a função vascular prevenindo o agravamento do processo aterosclerótico. Camundongo apoE-/-, modelo experimental de aterosclerose espontânea, tem se mostrado uma valiosa ferramenta no estudo dessa doença. O objetivo deste estudo foi verificar a capacidade de treinamento dos camundongos apoE-/- e verificar a influência do treinamento físico na senescência de células vasculares e na lesão aterosclerótica. Camundongos apoE -/- (n=16) e C57BL/6 (n=16) machos de 4 ½ meses de idade foram divididos em grupo treinado e sedentário. O treino correspondeu a: 1 hora/dia, 50-70% da velocidade máxima de corrida, 5 vezes/semana, 5 semanas. Foram realizadas medidas de colesterol, pressão arterial (PA) e freqüência cardíaca (FC). Após o treino os animais foram eutanasiados, a aorta retirada e incubada em uma solução X-gal (pH 6.0) para caracterização colorimétrica (cor azul) da senescência e posterior quantificação de área de placa. Os dados estão expressos como média ± EPM. Para análise estatística foi usado ANOVA 2-vias, seguida do post hoc de Fisher, **p? 0,05. Foi encontrada senescência vascular nos animais apoE-/- e o treinamento aeróbico não reduziu a área de lesão aterosclerótica, embora observou-se uma tendência de redução de área de senescência de células vasculares. A capacidade de corrida dos grupos C57 e apoE-/- não foi diferente antes do programa de treinamento, no entanto, o mesmo aumentou a capacidade máxima de corrida dos animais quando comparado aos sedentários, com ganho percentual de 36 e 42% na velocidade máxima alcançada nos grupos C57 e apoE -/- treinados, respectivamente. Os animais apoE -/- apresentaram hipercolesterolemia (sedentário: 646±75##, treinado: 664±66## mg/dL) em relação aos C57 (sedentário: 161±16, treinado: 102±12 mg/dL), e o treino não influenciou o colesterol, FC e PA. Os camundongos apoE-/- apresentaram o mesmo ganho de performance física com o treino que os animais C57. Apesar da área de lesão de placa não ter sido reduzida com o treino, observou-se uma tendência de redução de senescência nos animais ateroscleróticos, sugerindo um possível efeito do treinamento aeróbico na redução do desenvolvimento precoce de senescência vascular

Laparoscopic colorectal resection for a giant colonic diverticulum - video vignette

A giant colonic diverticulum (GCD) is a rare disease with less than 200 cases reported in the literature. By definition, a GCD is larger than 4cm in diameter with close sigmoid colon relationship in more than 90% of the cases. En bloc resection of the diverticulum with anterior sigmoid-rectal segment with primary anastomosis is the best treatment approach. The authors present a case of laparoscopic colorectal resection with partial cystectomy for a giant colonic diverticulum. A 62-years-old man with sigmoid colon diverticulosis and several episodes of diverticulitis presented at the office with a painless hypogastric/left iliac abdominal mass. CT scan showed a round 11 cm smooth walled structure filled with gas, adjacent to the sigmoid anti-mesenteric border and the urinary bladder. Four trocars were used for the laparoscopic approach. Step-by-step as follows: i. complete mobilization of colon splenic flexure. ii. Giant diverticulum dissection with partial bladder resection. iii. Bladder closure. iv. Sigmoid colon and intra-peritoneal rectum resection with primary anastomosis. The post-operative course was uneventful and the patient was discharged home on post-operative day 4. Vesical catheter was removed on post-operative day 10. Pathological specimen analysis confirmed the pre-operative diagnosis of a GCD. There is a consensus that this extremely rare diverticular disease complication should be approached with prompt standard resection due to high risk of diverticulum rupture. Laparoscopic approach seems to be feasible and safe despite of dissection higher complexity owing to the mega diverticulum. This article is protected by copyright. All rights reserved.info:eu-repo/semantics/publishedVersio

Effects of alkaline and acid solutions on glass/epoxy composites

Composite structures can be exposed to a range of corrosive environments during their in-service life, which causes degradation in terms of material properties. The effect of alkaline and acid solutions on the GRP mechanical properties can be found in open literature, but the studies presented are not sufficient to establish a full knowledge of this subject. In this paper the flexural properties and the impact strength of a glass fibre/epoxy composite after immersion in hydrochloric acid (HCl) and sodium hydroxide (NaOH) were analysed. Independently of the solution, the flexural strength and the flexural modulus decrease with the exposure time. However, alkaline solution promotes higher decrease of the flexural properties than the acid solution. The same tendency was observed for impact strength

Stationary roller versus velodrome for maximal cycling test: a comparison

The present study aimed to compare the acute cardio-respiratory responses of elite cyclists to a maximal progressive exercise carried out in two different conditions: in a laboratory (using a braked roller) and in an uncovered velodrome. In both testing conditions, ten elite male cyclists (age, 22.3 ± 3.9 years) performed a maximal discontinuous progressive test of 6 minutes per level with 150 W of initial load and increasing 50 W at each level until exhaustion. The heart rate and the ventilation parameters were measured breath-by-breath using a portable metabolic cart gas analysis system with telemetry data transmission. In the first 4 levels of effort, no significant differences were found between the two test conditions regarding VO2, (p=0.193), heart rate (p=0.973) and pedaling cadence (p=0.116). Comparing the maximum values achieved by each athlete in both exercise conditions, significant differences were found for heart rate (p=0.008) and pedaling cadence (p=0.005) but not for VO2max and peak power. Each variable showed a strong correlation between both assessments (VO2, r=0.984, p=0,000; heart rate, r=0.944, p=0.005; pedaling cadence, r=0.900, p=0.014). The amount of variability explained by the linear regression model for both cardio-respiratory parameters also showed a good fit value close to one (VO2max, r2=0.968; heart rate, r2=0.892). Our results suggest that identical cycling protocols conducted in different testing conditions with the same bike leads to equivalent performance but significantly different pedaling cadence and heart rate responses

Detection of Change in Fluorescence Between Reactive Cyan and the Yellow Fluorophores Usinga-SiC:H Multilayer Transducers

Optical colour sensors based on multilayered a-SiC:H heterostructures can act as voltage controlled optical filters in the visible range. In this article we investigate the application of these structures for Fluorescence Resonance Energy Transfer (FRET) detection, The characteristics of a-SiC:H multilayered structure are studied both theoretically and experimentally in several wavelengths corresponding to different fluorophores. The tunable optical p-i'(a-SiC:H)-n/p-i(a-Si:H)-n heterostructures were produced by PECVD and tested for a proper fine tuning in the violet, cyan and yellow wavelengths. The devices were characterized through transmittance and spectral response measurements, under different electrical bias and frequencies. Violet, cyan and yellow signals were applied in simultaneous and results have shown that they can be recovered under suitable applied bias. A theoretical analysis supported by numerical simulation is presented

Palliative splenic irradiation for symptomatic splenomegaly in non-Hodgkin lymphoma

INTRODUCTION AND AIMS: Splenic marginal zone lymphoma, an uncommon subtype of non-Hodgkin lymphoma (NHL), is usually present with symptomatic splenomegaly. Although splenectomy has long been considered the first-line therapy in symptomatic or cytopenic patients, it can lead to significant morbidity and mortality. Splenic irradiation is an option for patients who have a poor response to systemic therapy and/or are not surgical candidates. In this paper, we present a case report of a patient who received splenic radiotherapy for symptomatic splenomegaly. METHODS: An 85-year-old Caucasian man with a 4 year history of low-grade NHL presented with progressive pancytopenia, significant weight loss and symptomatic splenomegaly (abdominal discomfort, sense of fullness and limitation of mobility due to spleen size). The patient refused splenectomy and, in December 2017, was referred to palliative splenic radiotherapy. He was initially treated with five fractions of one Grey (Gy) in order to evaluate clinical and haematology response. After that, 1.5 Gy daily, 5 days a week for 3 weeks. 3D conformal radiotherapy, multiple fields and mixed energy (6 and 15 Mv) were used. RESULTS: Radiotherapy allowed significant splenic reduction to almost half the size, resolving abdominal discomfort and improving quality of life. There was no decline of haemoglobin, leukocytes and platelet counts; in fact, there was a marginal increase. CONCLUSION: Palliative splenic irradiation was well tolerated confirming that it is a safe treatment option for palliation of symptomatic splenomegaly. Thereby, splenic irradiation should be strongly considered in the management of symptomatic splenomegaly, for selected patients who are refractory to or unsuitable for other options or when the patient refuses other treatments.info:eu-repo/semantics/publishedVersio