Valuation of banana peel waste for producing activated carbon via NaOH and pyrolysis for methylene blue removal

Maia Lana S.,Duizit Letícia D.,Pinhatio Fernanda R.,Mulinari Daniella R. 한국탄소학회 2021 Carbon Letters Vol.31 No.4

The discharge of dye-containing industrial efuents such as methylene blue (MB) in water bodies has resulted in severe aquatic and human life problems. In addition to this factor, there is the accumulation of banana peel wastes, which can generate ecological damage. Thus, this research purpose a diferent method from the literature using the banana peel waste (BP) to produce activated carbon (ACBP) by NaOH activation followed by pyrolysis at 400 °C to remove methylene blue (MB). The material was characterized by TGA, XRD, SEM, BET, and FTIR. The infuence of dye concentration (10, 25, 50, 100, 250, and 500 mg L−1) was investigated. ACBP presented a well-developed pore structure with a predominance of mesopores and macropores. This morphological structure directly infuences the MB removal capacity. The highest efciency for dye removal was in the MB initial concentration of 25 mg L−1, sorbent of 0.03 g, and contact time of 60 min, which were 99.8%. The adsorption isotherms were well defned by Langmuir, Freundlich, and Temkin isotherm models. The Langmuir model represented the best ft of experimental data for ACBP with a maximum adsorption capacity of 232.5 mg g−1. This adsorbent showed a comparatively high performance to some previous works. So, the banana peel waste is an efcient resource for producing activated carbon and the adsorption of methylene blue.

Mathematics Learning in an Informal Environment at a Portuguese Kindergaten

( Maia Joao Sampaio ),( Menino Conceicao ) 한국수학교육학회 2011 수학교육 학술지 Vol.2011 No.-

Instead of prepare specific activities for teach mathematical ideas, some kindergarten teachers prefer to promote mathematics knowledge in an informal environment, assuming this is the best way to develop children creativity. In this paper, we present activities where children learn mathematics in non-mathematical situations and use their knowledge to solve their problems in daily kindergarten life. In each situation, children must accomplish some tasks where they have to count and to write their counting. They show what they have learned and they show their creativity using their knowledge in different actions.

Attitudinal modalities of citizenship representation styles in Georgia

Maia Mestvirishvili 한양대학교 아태지역연구센터 2019 Journal of Eurasian Studies Vol.10 No.2

This study investigates citizenship representation styles and their compositional modalities in contemporary Georgia. The article starts with a discussion of legal, social, and political influences that shaped conceptions of citizenship in post-Soviet countries, including Georgia. The study presents the results of a survey of 700 students from 10 universities in Georgia. They completed questionnaires exploring citizenship styles and associated predictor variables. The study suggests that a cultural citizenship style is dominant among Georgian students. It is best predicted by the level of national identification, followed by patriotism, nationalism, in-group attitudes, and religious orthodoxy. The data also show the opposing roles of nationalism and patriotism on ethnic and civic citizenship styles. The article argues that a cultural citizenship representation style could be the compromise solution in the ethnic versus civic citizenship dichotomy and might be more appropriate for societies characterized by ethno-nationalist tendencies.

건축 요소와 방재 시스템이 화재 발생 및 연기 흐름에 미치는 영향 - 제천 스포츠센터 화재 사례 분석-

Camilla Maia,이상원,이성은,박선영 한국화재조사학회 2018 한국화재조사학회 학술대회 Vol.2018 No.04

본 연구에서는 지난해 12월 충청북도 제천시에서 발생한 스포츠 센터 건물 화재를 바 탕으로 실제 상황과는 다른 두 개의 시나리오를 기획하고 Fire Dynamics Simulator(FDS) 를 통해 화재의 발생 및 연기의 흐름을 시뮬레이션 하였다. 화재 발생지인 1층과 희생자 가 다수 발생한 2층의 여자 사우나를 중심으로 모델링하였고 분석하였다. 시뮬레이션 결 과 두 개의 시나리오는 실제 상황과 다른 결과를 초래하지 않았다. 향후 연구에서는 주 변 상황과 건물 전체 등 본 연구에서 고려하지 않은 점을 바탕으로 이상적인 시나리오 를 찾는 연구가 필요하다. 본 연구는 실제 화재를 바탕으로 사상자 수 감소의 가능성을 타진했다는 점에서 그 의의가 있다. In this study, two hypothetical scenarios were planned based on the fire incident in the sports center building in Jecheon-si, Chungcheongbuk-do. The ignition and the smoke flow were simulated with Fire Dynamics Simulator(FDS). Due to the highest number of fatal victims on the second floor, where the women sauna was located, the analysis was focused on ground and second floors. The simulation results show that the two scenarios analyzed did not produce a different result from the actual accident. In future research, it would be recommended to study the ideal scenarios based on what is not considered in this study such as the surrounding situation and the entire building. This study is meaningful because it helps consider the possible reduction of casualties based on actual fire simulation.

Face Detection and Recognition in Color Images under Matlab

Deise Maia,Roque Trindade 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.2

In this paper we describe our implementation of algorithms for face detection and recognition in color images under Matlab. For face detection, we trained a feedforward neural network to perform skin segmentation, followed by the eyes detection, face alignment, lips detection and face delimitation. The eyes were detected by analyzing the chrominance and the angle between neighboring pixels and, then, the results were used to perform face alignment. The lips were detected based on the analysis of the Red color component intensity in the lower face region. Finally, the faces were delimited using the eyes and lips positions. The face recognition involved a classifier that used the standard deviation of the difference between color matrices of the faces to identify the input face. The algorithms were run on Faces 1999 dataset. The proposed method achieved 96.9%, 89% and 94% correct detection rate of face, eyes and lips, respectively. The correctness rate of the face recognition algorithm was 70.7%.

Modulus of elasticity of concretes produced with basaltic aggregate

Lino Maia,Farhad Aslani 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.17 No.1

Basalt is a type of volcanic rocks, grey to black in colour, contains less than 20% quartz, 10% feldspathoid, and at least 65% of the feldspar of its volume. Basalt is considered an igneous rock with fine grains due to the rapid cooling of lava. Basaltic rocks have been widely used as aggregate for various purposes. The study presented in this paper was carried out on basalts that are widespread in the Madeira Island of Portugal and that comprise the major source of local crushed rock aggregates. This paper discusses an experimental programme that was carried out to study the effects of basaltic aggregate on the compressive strength and modulus of elasticity of concrete. For this purpose, cylinder specimens with 150×300 mm dimensions and prism specimens with 150×150×375 mm dimensions were cast. The experimental programme was carried out with several concrete compositions belonging to strength classes C20/25, C25/30, C30/37, C40/50 and C60/75. The Eurocode 2 indicates the modulus of elasticity should be 20% higher when the aggregates are of basaltic origin, however results showed significant differences and a correction is proposed.

Low back pain, obesity, and inflammatory markers : exercise as potential treatment

Isabela Maia da Cruz Fernandes,Rafael Zambelli Pinto,Paulo Ferreira,Fábio Santos Lira 한국운동재활학회 2018 JER Vol.14 No.2

Comparison of light-transmittance in dental tissues and dental composite restorations using incremental layering build-up with varying enamel resin layer thickness

Rocha Maia, Rodrigo,Oliveira, Dayane,D'Antonio, Tracy,Qian, Fang,Skif, Frederick The Korean Academy of Conservative Dentistry 2018 Restorative Dentistry & Endodontics Vol.43 No.2

Objectives: To evaluate and compare light-transmittance in dental tissues and dental composite restorations using the incremental double-layer technique with varying layer thickness. Materials and Methods: B1-colored natural teeth slabs were compared to dental restoration build-ups with A2D and B1E-colored nanofilled, supra-nanofilled, microfilled, and microhybrid composites. The enamel layer varied from 0.3, 0.5, or 1.2 mm thick, and the dentin layer was varied to provide a standardized 3.7 mm overall sample thickness (n = 10). All increments were light-cured to $16J/cm^2$ with a multi-wave LED (Valo, Ultradent). Using a spectrophotometer, the samples were irradiated by an RGB laser beam. A voltmeter recorded the light output signal to calculate the light-transmittance through the specimens. The data were analyzed using 1-way analysis of variance followed by the post hoc Tukey's test (p = 0.05). Results: Mean light-transmittance observed at thicker final layers of enamel were significantly lower than those observed at thinner final layers. Within 1.2 mm final enamel resin layer (FERL) thickness, all composites were similar to the dental tissues, with exception of the nanofilled composite. However, within 0.5 mm FERL thickness, only the suprananofilled composite showed no difference from the dental tissues. Within 0.3 mm FERL thickness, none of the composites were similar to the dental tissues. Conclusions: The supra-nanofilled composite had the most similar light-transmittance pattern when compared to the natural teeth. However, for other composites, thicker FERL have a greater chance to match the light-transmittance of natural dental tissues.

Comparison of light-transmittance in dental tissues and dental composite restorations using incremental layering build-up with varying enamel resin layer thickness

Rodrigo Rocha Maia 대한치과보존학회 2018 Restorative Dentistry & Endodontics Vol.43 No.2

Objectives To evaluate and compare light-transmittance in dental tissues and dental composite restorations using the incremental double-layer technique with varying layer thickness. Materials and Methods B1-colored natural teeth slabs were compared to dental restoration build-ups with A2D and B1E-colored nanofilled, supra-nanofilled, microfilled, and microhybrid composites. The enamel layer varied from 0.3, 0.5, or 1.2 mm thick, and the dentin layer was varied to provide a standardized 3.7 mm overall sample thickness (n = 10). All increments were light-cured to 16 J/cm2 with a multi-wave LED (Valo, Ultradent). Using a spectrophotometer, the samples were irradiated by an RGB laser beam. A voltmeter recorded the light output signal to calculate the light-transmittance through the specimens. The data were analyzed using 1-way analysis of variance followed by the post hoc Tukey's test (p = 0.05). Results Mean light-transmittance observed at thicker final layers of enamel were significantly lower than those observed at thinner final layers. Within 1.2 mm final enamel resin layer (FERL) thickness, all composites were similar to the dental tissues, with exception of the nanofilled composite. However, within 0.5 mm FERL thickness, only the supra-nanofilled composite showed no difference from the dental tissues. Within 0.3 mm FERL thickness, none of the composites were similar to the dental tissues. Conclusions The supra-nanofilled composite had the most similar light-transmittance pattern when compared to the natural teeth. However, for other composites, thicker FERL have a greater chance to match the light-transmittance of natural dental tissues.

Detection and Diagnosis Solutions for Fault-Tolerant VSI

Armando Cordeiro,Joao C. P. Palma,Jose Maia,Maia J. Resende 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.6

This paper presents solutions for fault detection and diagnosis of two-level, three phase voltage-source inverter (VSI) topologies with IGBT devices. The proposed solutions combine redundant standby VSI structures and contactors (or relays) to improve the fault-tolerant capabilities of power electronics in applications with safety requirements. The suitable combination of these elements gives the inverter the ability to maintain energy processing in the occurrence of several failure modes, including short-circuit in IGBT devices, thus extending its reliability and availability. A survey of previously developed fault-tolerant VSI structures and several aspects of failure modes, detection and isolation mechanisms within VSI is first discussed. Hardware solutions for the protection of power semiconductors with fault detection and diagnosis mechanisms are then proposed to provide conditions to isolate and replace damaged power devices (or branches) in real time. Experimental results from a prototype are included to validate the proposed solutions.