Functional Gradient Materials : REACTIVE HOT COMPACTION OF FUNCTIONALLY GRADED COMPOSITES

A . Gomez,H . F . Wang,H . Doty,R . Abbaschian 대한금속재료학회 ( 구 대한금속학회 ) 1995 Advanced Material and Processing Vol.2 No.-

Bio-structural monitoring of bone mineral alterations through electromechanical impedance measurements of a Piezo-device joined to a tooth

Tinoco Hector A.,Cardona Carlos I.,Marín-Berrio Maribel L. F.,García-Grisales Juliana,Gomez Juan P.,Roldan Samuel I.,Peña Fabio M.,Brinek Adam,Kalasová Dominika,Kaiser Jozef,Zikmund Tomas 대한의용생체공학회 2020 Biomedical Engineering Letters (BMEL) Vol.10 No.4

Bone presents different systemic functionalities as calcium phosphate reservoir, organ protection, among others. For that reason, the bone health conditions are essential to keep in equilibrium the metabolism of several body systems. Different technologies exist to diagnose bone conditions with invasive methods based on ionizing radiation. Therefore, there is a challenge to develop new ways to evaluate bone alterations in a noninvasive form. This study shows the assessment of a piezo-actuated device acting on a human tooth for the bio-monitoring of bone alterations. The bone diagnosis is performed by applying the electromechanical impedance technique (EMI), commonly used in structural health monitoring. For the experimental tests, five bone samples were prepared, and one was chosen as the monitoring. All samples were put in a decalcifying substance (TBD1 acid–base) at different times to emulate localized bone mineral alterations. Bone reductions were computed by using X-ray micro-computed tomography analyzing the morphometry. Electrical resistance measurements (piezo-device) were taken for the monitoring specimen meanwhile it was partially decalcified during 8520 seconds. In the frequency spectrum, several observation windows showed that the bone alterations gradually changed the electrical resistance signals which were quantified statistically. Results evidenced that the bone density changes are correlated with the electrical resistance measurements; these changes presented an exponential behavior as much as in the calculated index, and bone mineral reduction. The results demonstrated that bone alterations exhibit linear dependence with the computed statistical indexes. This result confirms that it is possible to observe the bone changes from the teeth as a future application.

Total reference-free displacements for condition assessment of timber railroad bridges using tilt

Ali I. Ozdagli,Jose A. Gomez,Fernando Moreu 국제구조공학회 2017 Smart Structures and Systems, An International Jou Vol.20 No.5

The US railroad network carries 40% of the nation\'s total freight. Railroad bridges are the most critical part of the network infrastructure and, therefore, must be properly maintained for the operational safety. Railroad managers inspect bridges by measuring displacements under train crossing events to assess their structural condition and prioritize bridge management and safety decisions accordingly. The displacement of a railroad bridge under train crossings is one parameter of interest to railroad bridge owners, as it quantifies a bridge\'s ability to perform safely and addresses its serviceability. Railroad bridges with poor track conditions will have amplified displacements under heavy loads due to impacts between the wheels and rail joints. Under these circumstances, vehicle-track-bridge interactions could cause excessive bridge displacements, and hence, unsafe train crossings. If displacements during train crossings could be measured objectively, owners could repair or replace less safe bridges first. However, data on bridge displacements is difficult to collect in the field as a fixed point of reference is required for measurement. Accelerations can be used to estimate dynamic displacements, but to date, the pseudo-static displacements cannot be measured using reference-free sensors. This study proposes a method to estimate total transverse displacements of a railroad bridge under live train loads using acceleration and tilt data at the top of the exterior pile bent of a standard timber trestle, where train derailment due to excessive lateral movement is the main concern. Researchers used real bridge transverse displacement data under train traffic from varying bridge serviceability levels. This study explores the design of a new bridge deck-pier experimental model that simulates the vibrations of railroad bridges under traffic using a shake table for the input of train crossing data collected from the field into a laboratory model of a standard timber railroad pile bent. Reference-free sensors measured both the inclination angle and accelerations of the pile cap. Various readings are used to estimate the total displacements of the bridge using data filtering. The estimated displacements are then compared to the true responses of the model measured with displacement sensors. An average peak error of 10% and a root mean square error average of 5% resulted, concluding that this method can cost-effectively measure the total displacement of railroad bridges without a fixed reference.

Development of microporous-activated carbons derived from two renewable precursors for CO2 capture

Gomez-Delgado E.,Nunell G. V.,Cukierman A. L.,Bonelli P. R. 한국탄소학회 2020 Carbon Letters Vol.30 No.2

Wood sawdust from an invasive arboreal species, Parkinsonia aculeata, and seeds from a tropical fruit of massive consump�tion, Pouteria sapota, were used as precursors for the development of activated carbons (ACs) directed to CO2 adsorption. Chemical activation employing KOH as activating agent and pre-established experimental conditions was applied. Main physicochemical properties of the ACs in relation to their CO2 adsorption performance were examined. The ACs developed from the wood sawdust and the seeds presented specifc surfaces areas of 770 and 1000 m2 g−1, respectively, with their porosity development resulting essentially microporous (< 2 nm). They also showed a similar content of acidic surface groups, but basic functionalities of the former duplicated those of the latter. Maximum CO2 adsorbed at equilibrium (273 K and 100 kPa) was 5.0 mmol g−1 and 4.4 mmol g−1 for the samples derived from the sawdust and the seeds, respectively. On the other hand, CO2 adsorption capacities mimicking post-combustion conditions, as evaluated from thermogravimetric assays and breakthrough curves obtained in a packed-bed column, were approximately 1 mmol g−1, indicating a good CO2 adsorption performance for both ACs. Nevertheless, those derived from the wood sawdust with a notorious preeminence of micropores (~ 93%), narrower pore size distribution centered around 1 nm, and a higher content of basic functionalities than the ACs obtained from the seeds showed a relatively better performance. The CO2 removal capacity of the activated carbons was not noticeably afecte

Synaptic Vesicle Protein 2 (SV2) Isoforms

Bandala, Cindy,Miliar-Garcia, A.,Mejia-Barradas, C.M.,Anaya-Ruiz, M.,Luna-Arias, J.P.,Bazan-Mendez, C.I.,Gomez-Lopez, M.,Juarez-Mendez, S.,Lara-Padilla, E. Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.10

New molecular markers of cancer had emerged with novel applications in cancer prevention and therapeutics, including for breast cancer of unknown causes, which has a high impact on the health of women worldwide. The purpose of this research was to detemine protein and mRNA expression of synaptic vesicle 2 (SV2) isoforms A, B and C in breast cancer cell lines. Cultured cell lines MDA-MB-231, SKBR3, T47D were lysed and their protein and mRNA expression analyzed by real-time PCR and western blot technique, respectively. SV2A, B proteins were identified in non-tumor (MCF-10A) and tumor cell lines (MDA-MB-231 and T47D) while SV2C only was found in the T47D cell line. Furthermore, the genomic expression was consistent with protein expression for a such cell line, but in MDA-MB-231 there was no SV2B genomic expression, and the SV2C mRNA and protein were not found in the non tumoral cell line. These findings suggest a possible cellular transdifferentiation to neural character in breast cancer, of possible relevance to cancer development, and point to possible use of SV2 as molecular marker and a vehicle for cancer treatment with botulinum toxin.

Comparison of physicochemical properties of bio and commercial hydroxyapatite

A.L. Giraldo-Betancur,D.G. Espinosa-Arbelaez,A. del Real-López,B.M. Millan-Malo,E.M. Rivera-Muñoz,E. Gutierrez-Cortez,P. Pineda-Gomez,S. Jimenez-Sandoval,M.E. Rodriguez-García 한국물리학회 2013 Current Applied Physics Vol.13 No.7

This article reports a physicochemical comparison of synthetic and biological Hydroxyapatite (HAp). Eight samples were separated into two groups: bio and commercial hydroxyapatite (bio-HAp and commercial-HAp). The bio-HAp group containing defat, alkaline, and calcined samples taken from bovine bone were obtained by using three different treatments, in order to establish their effect on the final product quality. The commercial-HAp group, from different sources: NIST, sigma, apafill G, coralina, and biograft, were analyzed and compared with the bio-HAp results. Thermogravimetric analysis (TG) was used in order to establish thermal degradation of the samples; structural behavior was then analyzed by X-Ray Diffraction (XRD) to found the crystalline phases, as well as the crystalline quality. Fourier Transform Infrared Spectroscopy (FTIR) was performed in order to identify the corresponding HAp functional groups within the samples. The surface morphology was analyzed by Scanning Electron Microscopy (SEM) and the elemental composition was established by using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). It was found that the calcination process obtains HAp with comparable quality to the commercial samples. A crystallinity greater than 62% after the alkaline process was found. Additionally, the surface of the alkaline sample presents a transition behavior between dense and porous morphology.

Network Localization with Assisting Nodes

Carlos A. Gomez-Vega,Zhenyu Liu,Carlos A. Gutierrez,Andrea Conti,Moe Z. Win 한국통신학회 2021 한국통신학회 학술대회논문집 Vol.2021 No.2

Location awareness in wireless networks depends on propagation conditions, transmitting resources, and nodes deployment. A well designed node deployment strategy can enhance the localization performance significantly. In this paper, we present a near-optimal algorithm for deploying assisting nodes in localization networks with limited infrastructure. First, we formulate the node deployment task as an optimization problem to minimize the localization error of an agent. Then, we develop a node deployment algorithm based on this formulation. Finally, we present a case study to validate the proposed algorithm.

Evaluation of the Mechanical and Fire Resistance Properties ofRigid Tannin Polyurethane Foams with Copper Oxide Nanoparticles

Andrés Díaz-Gomez,Mytzy Godoy,María Elizabeth Berrio,Jesús Ramirez,Andrés Felipe Jaramillo,Carlos Medina,Mary Montaño,Manuel Francisco Meléndrez 한국섬유공학회 2022 Fibers and polymers Vol.23 No.7

In this study, a polymerized polyurethane foam was formulated from tannins extracted from Pinus radiata aspolyol, and copper oxide nanoparticles (CuO-NPs) at a concentration of 2 % w/w as a nucleating agent. This produced areinforced foam with better mechanical properties and fire resistance. The impact of the addition of CuO-NPs on themechanical and thermal properties of the tannin foam was also studied. The properties studied were foaming process, foamdensity, cell morphology, flammability and thermal conductivity. The results revealed that the CuO-NPs incorporated in thefoam formulation act as nucleation centers, which decrease the pore size, strengthen the cell walls, and improve mechanicalproperties. The tannin samples showed good thermal resistance performance with a limit oxygen index (LOI) higher than21 %. The results obtained were contrasted with two foams, a commercial foam (SoudaFoam) and a foam generated with thesame dissociate, but with a commercial polyol (LHT-112). The foam with NPs had an elastic modulus of 3.7 MPa and stress(max) of 1.13 MPa, which was higher than those of the foams used as controls.

Monte Carlo Simulations for the Study of a Moderated Neutron Detector

M. B. Gomez Hornillos,V. Gorlychev,R. Caballero,G. Cortes,A. Poch,C. Pretel,F. Calvino,J. L. Tain,A. Algora,J. Agramunt,D. Cano-Ott,T. Martinez,E. Mendoza,J. Rissanen,J. Aysto,A. Jokinen,T. Eronen,I. 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

This work presents the Monte Carlo simulations performed with the MCNPX and GEANT4 codes for the design of a BEta deLayEd Neutron detector, BELEN-20. This detector will be used for the study of beta delayed neutron emission and consists of a block of polyethylene with dimensions 90 × 90 × 80 cm ^3 and 20 cylindrical ^3He gas counters. The results of these simulations have been validated experimentally with a ^(252)Cf source in the laboratory at UPC, Barcelona. Also the first experiment with this detector has been carried out in November 2009 in JYFL, Finland. In this experiment the neutron emission probability after beta decay of the fission products ^(88)Br, ^(94,95)Rb and ^(138)I has been measured; this data is still under analysis. Simulations with MCNPX and GEANT4 have been performed in order to obtain the efficiency of the BELEN-20 detector for each of the above nuclei using the neutron energy distribution corresponding to each nucleus.

Importance of the knowledge of pathological processes for risk-based inspection in pig slaughterhouses (Study of 2002 to 2016)

Pedro Sanchez,Francisco J. Pallares,Miguel A. Gomez,Antonio Bernabe,Serafin Gomez,Juan Seva 아세아·태평양축산학회 2018 Animal Bioscience Vol.31 No.11

Objective: The objective of this work was to determine the prevalence of the pathologies that caused the condemnation of pig carcasses in an area of intensive pig farming and Mediterranean climatology and to evaluate their influence in a risk-based inspection procedure for slaughterhouses. Methods: A retrospective observational investigation was carried out from 2002 to 2016 into the pathological processes that caused the condemnation of pig carcasses in a slaughterhouse from South-eastern Spain. The seasonal effect on the causes of condemnation carcass was reported. Negative binomial model was used to evaluate the effect of season on the rate of antemortem rejections and post-mortem condemnations. Histopathological examinations were performed to confirm the diagnosis. Results: The risk of antemortem rejections (0.0564%) was significantly greater in summer (risk ratio [RR] = 1.57). Autumn was associated with higher rate (RR = 1.69) of the total postmortem condemnations (0.1046%). Significantly higher rates of pronounced anaemia (0.0111%) were observed in summer (RR = 3.20). The main causes of anaemia were observed gastroesophageal ulcers and haemorrhagic enteropathies. Significantly highest risk of erysipelas (0.0074%) were observed in autumn (RR = 5.485). About other zoonosis, only eight cases (0.0013%) of carcasses were declared unfit due to tuberculosis lesions. Porcine muscular cysticercosis was not detected. Nevertheless, nonspecific causes such as generalized infections and emaciation represented the half of the condemned carcasses (50.90%). Conclusion: The pathologies leading to the condemnation of carcasses in this study can be considered representative of the pathologies that affect the pig population from a region with a high intensive production and Mediterranean climatology because this slaughterhouse receives a lot of animals from many farms of different size in a high intensive pig production zone (Mediterranean region). Increased knowledge of environmental factors that may foment the appearance of the diseases is essential for implementing inspection programs based on risk assessment in pig’s slaughterhouses.