Prediction of the mechanical properties of granites under tension using DM techniques

Martins, Francisco F.,Vasconcelos, Graca,Miranda, Tiago Techno-Press 2018 Geomechanics & engineering Vol.15 No.1

The estimation of the strength and other mechanical parameters characterizing the tensile behavior of granites can play an important role in civil engineering tasks such as design, construction, rehabilitation and repair of existing structures. The purpose of this paper is to apply data mining techniques, such as multiple regression (MR), artificial neural networks (ANN) and support vector machines (SVM) to estimate the mechanical properties of granites. In a first phase, the mechanical parameters defining the complete tensile behavior are estimated based on the tensile strength. In a second phase, the estimation of the mechanical properties is carried out from different combination of the physical properties (ultrasonic pulse velocity, porosity and density). It was observed that the estimation of the mechanical properties can be optimized by combining different physical properties. Besides, it was seen that artificial neural networks and support vector machines performed better than multiple regression model.

A novel method of objectively detecting tooth ankylosis using cone-beam computed tomography: A laboratory study

Martins Luciano Augusto Cano,Brasil Danieli Moura,Freitas Deborah Queiroz,Oliveira Matheus L 대한영상치의학회 2023 Imaging Science in Dentistry Vol.53 No.1

Purpose: The aim of this study was to objectively detect simulated tooth ankylosis using a novel method involving cone-beam computed tomography (CBCT). Materials and Methods: Tooth ankylosis was simulated in single-rooted human permanent teeth, and CBCT scans were acquired at different current levels (5, 6.3, and 8 mA) and voxel sizes (0.08, 0.125, and 0.2). In axial reconstructions, a line of interest was perpendicularly placed over the periodontal ligament space of 21 ankylosed and 21 non-ankylosed regions, and the CBCT grey values of all voxels along the line of interest were plotted against their corresponding X-coordinates through a line graph to generate a profile. The image contrast was increased by 30% and 60% and the profile assessment was repeated. The internal area of the resulting parabolas was obtained from all images and compared between ankylosed and non-ankylosed regions under different contrast enhancement conditions, voxel sizes, and mA levels using multi-way analysis of variance with the Tukey post hoc test (α = 0.05). Results: The internal area of the parabolas of all non-ankylosed regions was significantly higher than that of the ankylosed regions (P<0.05). Contrast enhancement led to a significantly greater internal area of the parabolas of non- ankylosed regions (P<0.05). Overall, voxel size and mA did not significantly influence the internal area of the parabolas (P>0.05). Conclusion: The proposed novel method revealed a relevant degree of applicability in the detection of simulated tooth ankylosis; increased image contrast led to greater detectability.

Validation of 2D shock capturing flood models around a surcharging manhole

Martins, R.,Kesserwani, G.,Rubinato, M.,Lee, S.,Leandro, J.,Djordjević,, S.,Shucksmith, J. D. Informa UK (TaylorFrancis) 2017 Urban water journal Vol.14 No.9

<P>This work offers a detailed validation of finite volume (FV) flood models in the case where horizontal floodplain flow is affected by sewer surcharge flow via a manhole. The FV numerical solution of the 2D shallow water equations is considered based on two approximate Riemann solvers, HLLC and Roe, on both quadrilateral structured and triangular unstructured mesh-types. The models are validated against a high resolution experimental data-set obtained using a physical model of a sewer system linked to a floodplain via a manhole. It was verified that the sensitivity of the models is inversely proportional to the surcharged flow/surface inflow ratio, and therefore requires more calibration from the user especially when concerned with localised modelling of sewer-to-floodplain flow. Our findings provide novel evidence that shock capturing FV-based flood models are applicable to simulate localised sewer-to-floodplain flow interaction.</P>

Self-sustained n-Type Memory Transistor Devices Based on Natural Cellulose Paper Fibers

Martins, Rodrigo,Pereira, Luis,Barquinha, Pedro,Correia, Nuno,Goncalves, Goncalo,Ferreira, Isabel,Dias, Carlos,Correia, N.,Dionisio, M.,Silva, M.,Fortunato, Elvira The Korean Infomation Display Society 2009 Journal of information display Vol.10 No.4

Reported herein is the architecture for a nonvolatile n-type memory paper field-effect transistor. The device was built via the hybrid integration of natural cellulose fibers (pine and eucalyptus fibers embedded in resin with ionic additives), which act simultaneously as substrate and gate dielectric, using passive and active semiconductors, respectively, as well as amorphous indium zinc and gallium indium zinc oxides for the gate electrode and channel layer, respectively. This was complemented by the use of continuous patterned metal layers as source/drain electrodes.

Food toxicity assessment of selected canned foods in Nigeria

Martins O. Ainerua,Nosakhare Erhunmwunse,Isioma Tongo,Lawrence Ezemonye 한국독성학회 2020 Toxicological Research Vol.36 No.1

Food toxicity assessment was made for frequently consumed canned foods in Nigeria in order to estimate potential human health risks associated with their consumption. Levels of heavy metals (Pb, Cd, As, Fe, Mn and Zn), Nitrate and Nitrite, pH and salt were assessed in randomly purchased samples from groceries stores to represent what is readily available on the market. Nitrates and nitrites were assessed using a Perkin-Elmer spectrophotometer while heavy metal levels were determined using Atomic absorption spectrophotometer. Human health risk was estimated using standard indices; estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI) and dietary exposure (DE). Results showed varying concentrations of nitrates, nitrites, heavy metals, in all the canned food categories but the level of salt and pH seemed constant. Nitrate, Fe and Cd in all the canned food categories exceeded recommended limit set by EU. Health risk estimations showed EDI values for Cd in all the canned food categories above the tolerable daily intake, while DE for Fe in canned sweet corn, Fe, Zn and Pb in canned beans/peas had values above recommended limits. THQ values for all the canned foods were above 1 in the canned beans/peas while HI was above 1 in the canned fish category. The study revealed the potential for Cd toxicity and risk of non-carcinogenic health effects from canned beans/peas consumption. Constant monitoring of canned foods is therefore imperative considering the growing demand for canned products due to changing lifestyle.

Wound dressing using graphene quantum dots: a proof of concept

Martins Vanessa Gonzalez Ferreira Caminha,Alencar Luciana Magalhaes Rebelo,Souza Pedro Filho Noronha,Lorentino Carolinne Margot Albanez,Frota Heloisa Freire,dos Santos Andre Luis Souza,Gemini-Piperni 한국약제학회 2023 Journal of Pharmaceutical Investigation Vol.53 No.2

Purpose The costs and complexity related to effective wound healing treatment are immense. The number of multifactorial aspects related to the treatment of wounds (inflammation, infection, and many others) implies a complex multi-therapeutic approach involving various procedures, including medication and surgery. Regarding medication, there are only a few options, especially to treat chronic wounds. Recently graphene quantum dots have been applied for their potent antimicrobial properties as well as their significant tissue remodeling properties. In this study, we developed a formulation based on graphene quantum dots in the form of as a dry powder for wound healing. Methods Graphene quantum dots were produced by top-down technique using graphite as matrix, and fully characterized by Raman spectroscopy, atomic force microscopy, and X-ray diffractometry. The dry powder formulation was produced under aseptic conditions and evaluated in vitro and in vivo. Results The results showed that the formulation improved the healing process in both: in vitro and in vivo, with good adherence, healing time and tissue reconstruction. Finally, the results demonstrated that dry powder was very effective against P. aeruginosa, S. epidermidis, C. albicans and C. tropicalis, representing an improvementfor wound healing purposes. Conclusion The data corroborated the use of the dry powder formulation using graphene quantum dots as matrix as wound dressing, expanding the use of graphene quantum in the biomedical field.

First record of red macroalgae bloom in Southern Atlantic Brazil

Martins, Mateus S.,Massocato, Thais F.,Horta, Paulo A.,Barufi, Jose Bonomi The Korean Society of Phycology 2016 ALGAE Vol.31 No.1

Blooms of macroalgae have grown over the planet in recent decades as a possible result of eutrophication of coastal waters. Visually, a bloom forming can be identified by dominant presence of an organism at the expense of others. In mid-January 2014, a forming bloom of red algae was detected on the beach of Garopaba, Santa Catarina State, Brazil. This aroused the interest of tourists and locals as well as the scientific community. Thus, the objective of this study was to characterize and quantify the photosynthetic floating organisms contributing to this phenomenon. In addition, we qualitatively compared algal composition of the bloom to those deposited in the post-beach area and the adjacent rocky shore community. Five sampling points in random patches of floating material were defined. At each point, five replicates were taken with a cube of 32,768 cm³, resulting in a total of 25 samples. Samples were collected in the inner area enclosed by a PVC quadrate of about 900 cm² from the shore and the specimens found in post-beach zone (wrack). Twenty-four taxa of macroalgae were found in the bloom, with Aglaothamnion uruguayense as the dominance one. Ten taxa were found on shore. Only four taxa were found in the post-beach area. The biomass estimated for A. uruguayense in the floating material was 8.35 tons with an estimated area of 52,770 m² . It is possible that this huge biomass value of the bloom is related to the local nutrient intake, and our results reinforce the necessity of coastal integrative management initiatives.

Women in the Igbo Culture: Extrapolations from Nsukka, South-Eastern Nigeria

Martins N. Okoro 숙명여자대학교 아시아여성연구원 2022 Asian Women Vol.38 No.1

The study documents all the key aspects through which the cultural representation of the Nsukka town women is constructed. It seeks to investigate women’s involvement and participation in the cultural enactment of festivals, title-taking ceremonies, burials and funerals, marriage ceremonies, postpartum care, and conflict resolution, relying on materials from literature, ethnographic data, studies involving participant observation, and interview sessions with natives possessing a sufficient knowledge of culture and tradition. Data collected were examined using historical descriptive and analytical methods and the study is anchored in Jones Lewis’s theory of feminism which, among other criticisms, questions how much of our culture is based on patriarchal assumptions. The study found that even though women are subjugated in certain aspects of life, their involvement and participation in the enactments of cultural events and conflict management in Nsukka town give them some sense of belonging and that, without their involvement, such cultural and traditional events would not take place and their essence would be lost. These counter claim that men are often considered the drivers of cultural activities and as such belong to the public domain while women are confined purely to private life and domestic activities. The study is helpful in understanding the implications of women’s involvement and participation in the enactments of culture and tradition in Nsukka town.

Automated Synthesis of an Optimized 5.2㎓ Microstrip Antenna using Genetic Algorithm and an Accurate Transmission Line Model

Martins Chidozie Ezuma,Hui-Seon Gang,Jae-Young Pyun 한국정보기술학회 2016 한국정보기술학회논문지 Vol.14 No.3

This paper presents a computationally efficient approach for automating the process of synthesizing optimized microstrip antennas. The approach is used for designing an optimized 5.2㎓ microstrip antenna for wireless local area network (WLAN) applications. Indeed, the antenna is modeled as an equivalent circuit and an accurate transmission line technique is then used to analytically derive the input impedance of the target microstrip antenna when resonating at the fundamental TM01 mode. This input impedance is used to derive the fitness function for a robust genetic algorithm, which is to synthesize the optimized geometric parameters of the target microstrip antenna. The synthesized antenna is designed and simulated in the High Frequency Structural Simulator (HFSS) design environment, which is 3D EM simulation software. The plots of the reflection coefficient and the radiation patterns of the synthesized antenna are obtained in this environment. The simulation results show that the synthesized antenna has a good radiation property and resonates at the target frequency of 5.2㎓ with a return loss under -25㏈.

Characterization of Aspartate Aminotransferase Isoenzymes from Leaves of Lupinus albus L. cv Estoril

Martins, Maria Luisa Louro,De Freitas Barbosa, Miguel Pedro,De Varennes E Mendonca, Amarilis Paula Alberti Korean Society for Biochemistry and Molecular Biol 2002 Journal of biochemistry and molecular biology Vol.35 No.2

Two aspartate aminoransferase (EC 2.6.1.1) isoenzymes (AAT-1 and AAT-2) from Lupinus albus L. cv Estoril were separated, purified, and characterized. The molecular weight, pI value, optimum pH, optimum temperature, and thermodynamic parameters for thermal inactivation of both isoenzymes were obtained. Studies of the kinetic mechanism, and the kinetics of product inhibition and high substrate concentration inhibition, were performed. The effect of some divalent ions and irreversible inhibitors on both AAT isoenzymes was also studied. Native PAGE showed a higher molecular weight for AAT-2 compared with AAT-1. AAT-1 appears to be more anionic than AAT-2, which was suggested by the anion exchange chromatography. SDS-PAGE showed a similar sub-unit molecular weight for both isoenzymes. The optimum pH (between 8,0 and 9.0) and temperature ($60-65^{\circ}C$) were similar for both isoenzymes. In the temperature range of $45-65^{\circ}C$, AAT-2 has higher thermostability than AAT-1. Both isoenzymes showed a high affinity for keto-acid substrates, as well as a higher affinity to aspartate than glutamate. Manganese ions induced an increase in both AAT isoenzymes activities, but no cooperative effect was detected. Among the inhibitors tested, hydroxylamine affected both isoenzymes activity by an irreversible inhibition mechanism.