1,034 research outputs found
Avaliação in vitro do efeito da desproteinização da dentina decídua de humanos na união de sistemas adesivos
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Odontologia, Florianópolis, 2009.O objetivo deste estudo, in vitro, foi avaliar a resistência de união à microtração e a nanoinfiltração, após desproteinização da dentina decídua humana. Foram utilizadas coroas de molares decíduos hígidos, as quais tiveram a superfície oclusal desgastada com lixas de carbeto de silício, até a completa exposição da superfície dentinária, e para padronização da smear layer. Os espécimes foram distribuídos em seis grupos, de acordo com o tipo de tratamento (condicionamento ácido - CA ou CA + hipoclorito de sódio - NaOCl) e os sistemas adesivos: One Step Plus - Bisco (OSP), Single Bond - 3M ESPE (SB), Prime & Bond 2.1 - Dentsply (PB). Para o procedimento de desproteinização foi utilizado hipoclorito de sódio 10% por 30s. Os sistemas adesivos e a resina (Filtek Z 250 - 3M ESPE) foram aplicados de acordo com as recomendações dos fabricantes e os espécimes armazenados em água destilada (37ºC/24h). As coroas foram seccionadas obtendo-se palitos (0,8mm2), os quais foram imediatamente submetidos ao teste de resistência à microtração (Instron - 0,5mm/min), até fratura dos corpos-de-prova. Os valores obtidos foram analisados por ANOVA e teste de Tukey (p<0,05). Os corpos-de-prova foram levados ao microscópio eletrônico de varredura (MEV), para visualização do tipo de fratura e os dados submetidos ao teste de Kruskal-Wallis (p<0,05).A nanoinfiltração foi avaliada utilizando-se palitos e nitrato de prata amoniacal como marcador químico. A deposição da prata foi visualizada ao MEV e analisada de duas formas: 1. Em porcentagem (%), em três regiões do palito, utilizando-se espectometria por energia dispersa por raio-x (EDS); 2. Atribuição de escores pela avaliação das fotomicrografias obtidas ao MEV. Os dados (%) foram analisados por ANOVA e teste de Tukey (p<0,05) e os escores submetidos aos testes de Kruskal-Wallis e U de Mann-Whitney (p<0,05).Os valores médios obtidos para o teste de microtração sem desproteinização foram [MPa(DP)]: PB - 35,95(6,12); SB - 28,82(6,38); OSP - 24,59(6,10); e após desproteinização: PB - 41,47(6,79); OSP - 31,09(9,16); SB - 25,55(7,23). Os padrões de fratura mais comumente encontrados foram coesiva do adesivo e mista, para todos os grupos. A nanoinfiltração, avaliada por porcentagem, apresentou diferença significante para as variáveis tratamento e adesivo. A desproteinização da dentina condicionada reduziu significativamente a infiltração para o adesivo OSP. Para a variável sistema adesivo, na análise por porcentagem e por escores, o adesivo SB apresentou significativamente maior infiltração pelo nitrato de prata quando comparado ao OSP e PB, que foram similares entre si. Conclui-se que a resistência adesiva não foi influenciada pela remoção do colágeno exposto pelo condicionamento ácido e que a nanoinfiltração não foi evitada pela desproteinização dentinária
All-fibre-optic clock recovery from non-return-to-zero format data
No full textThe author; demonstrate an all-optical clock recovery scheme from non-return-to-zero format data, with an asymmetric Mach-Zehnder interferometer and a mode-locked Er-doped fibre laser. Since this scheme consists of an all-fibre device, the clock recovery bandwidth can extend to the terahertz region. Such all-optical clock recovery techniques will find application in ultra-high speed all-optical communication systems
A Nanopower 95.6% Efficiency Voltage Regulator with Adaptive Supply-Switching for Energy Harvesting Applications
No full textA nanopower highly efficient low-dropout (LDO) regulator for energy harvesting (EH) applications is presented in this paper. The LDO is fully autonomous with a bandgap reference (BGR) featuring a novel bandgap supply-switching (SS) topology, an over-voltage protection (OVP), a under-voltage lockout (UVLO) and control block to obtain stable output and robust cold-start. The system provides configurable voltage supply (1.1 \sim2V) for potential loads, while consuming as low as 66 nW power. The entire system achieves a peak power efficiency of 95.6% at Vout=2V and I-{\iota-{oad}}=100\muA.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Instrumentatio
External validation of anti-Müllerian hormone based prediction of live birth in assisted conception
No full text<p>Background - Chronological age and oocyte yield are independent determinants of live birth in assisted conception. Anti-Müllerian hormone (AMH) is strongly associated with oocyte yield after controlled ovarian stimulation. We have previously assessed the ability of AMH and age to independently predict live birth in an Italian assisted conception cohort. Herein we report the external validation of the nomogram in 822 UK first in vitro fertilization (IVF) cycles.</p>
<p>Methods - Retrospective cohort consisting of 822 patients undergoing their first IVF treatment cycle at Glasgow Centre for Reproductive Medicine. Analyses were restricted to women aged between 25 and 42 years of age. All women had an AMH measured prior to commencing their first IVF cycle. The performance of the model was assessed; discrimination by the area under the receiver operator curve (ROCAUC) and model calibration by the predicted probability versus observed probability.</p>
<p>Results - Live births occurred in 29.4% of the cohort. The observed and predicted outcomes showed no evidence of miscalibration (p = 0.188). The ROCAUC was 0.64 (95% CI: 0.60, 0.68), suggesting moderate and similar discrimination to the original model. The ROCAUC for a continuous model of age and AMH was 0.65 (95% CI 0.61, 0.69), suggesting that the original categories of AMH were appropriate.</p>
<p>Conclusions - We confirm by external validation that AMH and age are independent predictors of live birth. Although the confidence intervals for each category are wide, our results support the assessment of AMH in larger cohorts with detailed baseline phenotyping for live birth prediction.</p>
A graph-based model framework for steady-state load flow problems of general multi-carrier energy systems
No full textCoupling single-carrier networks into multi-carrier energy systems (MESs) has recently become more important. Conventional load flow models for the separate single-carrier networks are not able to capture the full extend of the coupling. Recently, different models for multi-carrier energy networks have been proposed, either using the energy hub (EH) concept, or using a case specific approach. Although the EH concept can be applied to a general MES, it is unclear how the EH should be represented in the graph of the MES. On the other hand, the case specific approaches are not easily applicable to general MESs. This paper presents a graph-based framework for steady-state load flow analysis of general MESs. Furthermore, the effect of coupling on the resulting integrated system of equations is investigated. The proposed framework is validated using a small MES. This example shows that our framework is applicable to a general MES, and that it generalizes both the EH concept and the case specific approach.Numerical Analysi
Design and Development of an RF Energy Harvesting Wireless Sensor Node (EH-WSN) for Aerospace Applications
No full textAbstractNumerous applications of wireless sensor networks are constrained by the limited battery power of the sensors. The power consumption of processors and microcontrollers could be scaled down dramatically with the new advances in microelectronics. This reduction gives rise to the possibility of energy harvesting sources to power wireless sensor nodes. In this paper a summary is given of our ongoing research work on RF Energy Harvesting Wireless Sensor Node (EH-WSN) which can plug-in to the already developed Wireless Instrumentation System (WIS) for aerospace applications. Present WSN's which are powered from battery have limited operational lifetime. While energy harvesting has the potential to enable near-perpetual system operation, design of which is a complex trade-off due to the interaction of numerous factors such as the characteristics of the energy source, power supply requirements, power management futures, WSN application behaviour, chemistry and capacity of batteries used etc. In this work, we have identified a suitable power harvesting cum battery management scheme which harvests power consistently and deterministically from a secondary RF source which can be used even in harsh real-time applications. Using a RF power harvesting receiver IC and a compact power management cum storage circuit, we establish the test bed and conduct a series of experiments to verify the effectiveness of the proposed scheme. We have demonstrated continuous operation of the sensor node at an operating distance of 2 meters from the RF power source for a data rate of 240 sps. This is achieved by using special synchronized MAC protocol, low power techniques, usage of low leakage components and systematic coding of the micro controller firmware. This paper provides an insight into how various power reduction techniques can be used and orchestrated such that satisfactory performance can be achieved for a given energy budget
Effect of the sampling parameters in FOCV-MPPT circuits for fast-varying EH sources
No full text© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The fractional open circuit voltage (FOCV) method is extensively used in low-power energy harvesting (EH) sources to extract maximum power. For fast-varying EH sources a fast sampling rate is required. This work theoretically analyzes the influence of the sampling time and period on the harvested power of sinusoidal EH sources. In addition, the circuit limitations to achieve a fast sampling rate are presented and circuits to deal with them proposed and implemented. Furthermore, one of the circuits is based on a novel pseudo-FOCV method and achieves the fastest sampling rate. Experimental tests are performed with a 2 Hz, 1 V to 3 V sinusoidal source having an output resistance of 127 ¿, and the results are shown to agree with theoretical predictions. It is shown that 1) the harvested power increases with the sampling rate when the sampling time is negligible (sampling 15 times faster than the source frequency extracts around 99 % of the maximum), and 2) for fixed sampling times there is an optimum sampling rate where the harvested power is maximum. The first result is generic and valid for methods other than the FOCV. Tests were also performed with a small-scale wave energy converter placed in a linear shaker emulating a sea environment. Harvested power increases by 25 % with respect using a commercial FOCV unit with a low sampling rate.This work was supported by the project MELOA from the European Commission’s Horizon 2020 research and Innovation program under Grant Agreement No. 776280 and by the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund under project TEC2016-76991-P. The first author has a grant from the Secretariat of Universities and Research of the Ministry of Business and Knowledge of the Government of Catalonia on the FI program (ref. BDNS 362582).Peer ReviewedPostprint (author's final draft
MEMS-based multi-modal vibration energy harvesters for ultra-low power autonomous remote and distributed sensing
No full textIn this contribution, we discuss the implementation of a novel microelectromechanical-systems (MEMS)-based energy harvester (EH) concept within the technology platform available at the ISAS Institute (TU Vienna, Austria). The device, already presented by the authors, exploits the piezoelectric effect to convert environmental vibrations energy into electricity, and presents multiple resonant modes in the frequency range of interest (i.e. below 10 kHz). The experimental characterisation of a sputter deposited aluminium nitride piezoelectric thin-film layer is reported, leading to the extraction of material properties parameters. Such values are then incorporated in the finite element method model of the EH, implemented in Ansys Workbench™, in order to get reasonable estimates of the converted power levels achievable by the proposed device solution. Multiphysics simulations indicate that extracted power values in the range of several µW can be addressed by the EH-MEMS concept when subjected to mechanical vibrations up to 10 kHz, operating in closed-loop conditions (i.e. piezoelectric generator connected to a 100 kΩ resistive load). This represents an encouraging result, opening up the floor to exploitations of the proposed EH-MEMS device in the field of wireless sensor networks and zero-power sensing nodes.</p
Impact of a Brief Prediabetes Education on Physical Activity, Eating Habit and Self-Efficacy in a Rural Primary Care Setting
No full textabstract: Purpose: The purpose of the project was to improve physical activity (PA), eating habits (EH) and self-efficacy (SE) by implementing short lifestyle modification education in a rural primary care setting.
Background: Although prediabetes awareness has slightly improved, the nationwide unawareness remains high. General knowledge about the disease and its risk factors and prevention are significant variables to adopt health-promoting behaviors. Lifestyle change intervention has been shown to be effective with the risk reduction behaviors in prediabetic population. However, it can be a daunting task to translate during short office visits.
Methods: Sixteen participants with risk for prediabetes or diagnosed prediabetes enrolled into a 5-minute education session in a rural health clinic. They received follow-up phone calls weekly for 4 weeks. Demographics, PA, EH and SE levels were measured before the education session. During the fourth week, PA, EH and SE were measured again. Frequency, descriptive analysis, and paired t-test were used for data analysis.
Outcomes: The mean age of participants was 56.6 13.0 years. Approximately 81% were female, and 62.5% identified as Caucasian. Over 80% reported married, and 56.3% described their health condition as good. The three quarters (75%) noted they have heard of the term prediabetes. The intervention had a significant effect on PA, EH and SE from the baseline to post intervention, p = .005, p = .008, and p = .003, respectively. Conclusion: This DNP project illustrated that one time brief lifestyle change education could positively impact PA, EH and SE in people with high risk for prediabetes in a primary care clinic
Sociocultural approach to intertextuality in malay novels: A reading of prasert eh chai’s phensi
No full textThe transmigration of Siamese people to Kelantan began as early as the middle of the 13th century. The formation of Siamese and Malay sociocultural and ethnic identity is said to be modern but still intact to traditional elements in life. However, the acceleration in the field of technology has marginalized traditional Thai socio-culture among the Siamese community of Kelantan. This study focused on observing the process and relationship between texts in the production of Malay novels. The process and relationship are linked to intertextuality, which is the phenomenon of text within a text or what is called dialogue between texts. This research framework utilized ideas by Julia Kristeva. The intertextual formula presented the relationship between the hypotext (short story) and the hypertext (novel) to see the meaning, the proposed process, and the appropriateness of the author. This study refers to Prasert Eh Chai’s novel Phensi (2022) which showed a tendency towards intertextual works. The study found that within the framework of intertextuality, Chai demonstrates loyalty to non-creative texts (the socio-cultural society of Siam Kelantan) which was later developed into a novel. Authorship style by Prasert Eh Chai shows his sensitivity in blending social experience into Phensi. This study summarizes the intertextuality of Chai’s Phensi not only physically from the socio-cultural viewpoint of the novel but also from the Siamese environment of Kelantan and the traditional roots of Thailand.A transmigração do povo siamês para Kelantan começou em meados do século XIII. A formação da identidade sociocultural e étnica siamesa e malaia é considerada moderna, mas ainda intacta em relação aos elementos tradicionais da vida. No entanto, a aceleração no domínio da tecnologia marginalizou a sociocultura tradicional tailandesa entre a comunidade siamesa de Kelantan. Este estudo centrou-se na observação do processo e da relação entre textos na produção de romances malaios. O processo e a relação estão ligados à intertextualidade, que é o fenómeno do texto dentro de um texto ou o chamado diálogo entre textos. Este quadro de investigação utilizou ideias de Julia Kristeva. A fórmula intertextual apresentou a relação entre o hipotexto (conto) e o hipertexto (romance) para ver o significado, o processo proposto e a adequação do autor. Este estudo refere-se ao romance Phensi (2022), de Prasert Eh Chai, que mostrou uma tendência para obras intertextuais. O estudo concluiu que, no âmbito da intertextualidade, Chai demonstra lealdade a textos não criativos (a sociedade sociocultural de Siam Kelantan), que mais tarde se transformou num romance. O estilo de autoria de Prasert Eh Chai mostra a sua sensibilidade ao misturar a experiência social com o Phensi. Este estudo resume a intertextualidade do Phensi de Chai não só fisicamente, do ponto de vista sociocultural do romance, mas também do ambiente siamês de Kelantan e das raízes tradicionais da Tailândia.
- …
