Emission properties of hydrothermal Yb^{3 +}, Er^{3 +} and Yb^{3 +}, Tm^{3 +}-codoped Lu₂O₃ nanorods: upconversion, cathodoluminescence and assessment of waveguide behavior

Barrera, Elixir William,Pujol, Marí,a Cinta,Dí,az, Francesc,Choi, Soo Bong,Rotermund, Fabian,Park, Kyung Ho,Jeong, Mun Seok,Cascales, Concepció,n IOP Pub 2011 Nanotechnology Vol.22 No.7

<P>Yb<SUP>3 + </SUP> and Ln<SUP>3 + </SUP> (Ln<SUP>3 + </SUP> = Er<SUP>3 + </SUP> or Tm<SUP>3 + </SUP>) codoped Lu<SUB>2</SUB>O<SUB>3</SUB> nanorods with cubic <img SRC='http://ej.iop.org/images/0957-4484/22/7/075205/nano368878ieqn1.gif' ALIGN='MIDDLE' ALT='Ia\bar 3 '/> symmetry have been prepared by low temperature hydrothermal procedures, and their luminescence properties and waveguide behavior analyzed by means of scanning near-field optical microscopy (SNOM). Room temperature upconversion (UC) under excitation at 980 nm and cathodoluminescence (CL) spectra were studied as a function of the Yb<SUP> + </SUP> concentration in the prepared nanorods. UC spectra revealed the strong development of <img SRC='http://ej.iop.org/images/0957-4484/22/7/075205/nano368878ieqn2.gif' ALIGN='MIDDLE' ALT='\mathrm {Er}^{3+}\,^{4}\mathrm {F}_{9/2}\to {}^4\mathrm {I}_{15/2} '/> (red) and <img SRC='http://ej.iop.org/images/0957-4484/22/7/075205/nano368878ieqn3.gif' ALIGN='MIDDLE' ALT='\mathrm {Tm}^{3+}\,{}^{1}\mathrm {G}_{4} \to {}^{3}\mathrm {H}_{6} '/> (blue) bands, which became the pre-eminent and even unique emissions for corresponding nanorods with the higher Yb<SUP>3 + </SUP> concentration. Favored by the presence of large phonons in current nanorods, UC mechanisms that privilege the population of <SUP>4</SUP>F<SUB>9/2</SUB> and <SUP>1</SUP>G<SUB>4</SUB> emitting levels through phonon-assisted energy transfer and non-radiative relaxations account for these observed UC luminescence features. CL spectra show much more moderate development of the intensity ratio between the <img SRC='http://ej.iop.org/images/0957-4484/22/7/075205/nano368878ieqn2.gif' ALIGN='MIDDLE' ALT='\mathrm {Er}^{3+}\, {}^{4}\mathrm {F}_{9/2} \to {}^4\mathrm {I}_{15/2} '/> (red) and <SUP>2</SUP>H<SUB>11/2</SUB>, <img SRC='http://ej.iop.org/images/0957-4484/22/7/075205/nano368878ieqn4.gif' ALIGN='MIDDLE' ALT='^{4}\mathrm {S}_{3/2}\to {}^{4}\mathrm {I}_{15/2} '/> (green) emissions with the increase in the Yb<SUP>3 + </SUP> content, while for Yb<SUP>3 + </SUP>, Tm<SUP>3 + </SUP>-codoped Lu<SUB>2</SUB>O<SUB>3</SUB> nanorods the dominant CL emission is <img SRC='http://ej.iop.org/images/0957-4484/22/7/075205/nano368878ieqn5.gif' ALIGN='MIDDLE' ALT='\mathrm {Tm}^{3+}\,{}^{1}\mathrm {D}_{2}\to {}^{3}\mathrm {F}_{4} '/> (deep-blue). Uniform light emission along Yb<SUP>3 + </SUP>, Er<SUP>3 + </SUP>-codoped Lu<SUB>2</SUB>O<SUB>3</SUB> rods has been observed by using SNOM photoluminescence images; however, the rods seem to be too thin for propagation of light. </P>

Inverted OPVs with MoS2 hole transport layer deposited by spray coating

Barrera, Diego,Jawaid, Ali,Daunis, Trey B.,Cheng, Lanxia,Wang, Qingxiao,Lee, Yun-Ju,Kim, Moon J.,Kim, Jiyoung,Vaia, Richard A.,Hsu, Julia W.P. ELSEVIER SCIENCE B.V. AMSTERDAM 2017 Materials today energy Vol.2017 No.5

Solution synthesis of few-layer 2H MX₂ (M = Mo, W; X = S, Se)

Barrera, Diego,Wang, Qingxiao,Lee, Yun-Ju,Cheng, Lanxia,Kim, Moon J.,Kim, Jiyoung,Hsu, Julia W. P. The Royal Society of Chemistry 2017 Journal of Materials Chemistry C Vol.5 No.11

<P>Two-dimensional transition metal dichalcogenides (TMDs) exhibit a wide range of properties depending on the chemistry of the transition metal element and the chalcogen, making them promising candidates for electronic applications. Current TMD thin films are either derived from bulk minerals, hence limited by the impurities, defects, and the availability of raw materials, or deposited using high vacuum or high reaction temperature processes. Here, we describe a versatile method to directly synthesize few-layer 2H MoS2, MoSe2, WS2, and WSe2 flakes from thermolysis of organometallic precursors in the presence of a chalcogen element using microwave-assisted heating. We study how the concentration of a reducing agent, 1,2-hexadecanediol, affects the chemical composition of TMDs using X-ray photoelectron spectroscopy (XPS). The crystalline phase of these materials is determined as trigonal prismatic (2H) using Raman spectroscopy and scanning transmission electron microscopy (STEM). Both STEM and atomic force microscopy (AFM) indicate that these flakes are a few layers thick (∼2 nm) with a relatively large lateral size (∼2 μm).</P>

Influence of Ionophore Supplementation on Growth Performance, Dietary Energetics and Carcass Characteristics in Finishing Cattle during Period of Heat Stress

Barreras, A.,Castro-Perez, B.I.,Lopez-Soto, M.A.,Torrentera, N.G.,Montano, M.F.,Estrada-Angulo, A.,Rios, F.G.,Davila-Ramos, H.,Plascencia, A.,Zinn, R.A. Asian Australasian Association of Animal Productio 2013 Animal Bioscience Vol.26 No.11

Forty-eight crossbred heifers ($378.1{\pm}18$ kg) were used in a 56-d feeding trial (four pens per treatment in a randomised complete block design) to evaluate the influence of ionophore supplementation on growth performance, dietary energetics and carcass characteristics in finishing cattle during a period of heat stress. Heifers were fed a diet based on steam-flaked corn (2.22 Mcal $NE_m/kg$) with and without an ionophore. Treatments were: i) control, no ionophore; ii) 30 mg/kg monensin sodium (RUM30); iii) 20 mg/kg lasalocid sodium (BOV20), and iv) 30 mg/kg lasalocid sodium (BOV30). Both dry matter intake (DMI) and climatic variables were measured daily and the temperature humidity index (THI) was estimated. The maximum THI during the study averaged 93, while the minimum was 70 (THI average = $79.2{\pm}2.3$). Compared to controls, monensin supplementation did not influence average daily gain, the estimated NE value of the diet, or observed-to-expected DMI, but tended (p = 0.07) to increase (4.8%) gain to feed. Compared to controls, the group fed BOV30 increased ($p{\leq}0.03$) daily gain (11.8%), gain to feed (8.3%), net energy of the diet (5%), and observed-to-expected DMI (5.2%). Daily weight gain was greater (7.6%, p = 0.05) for heifers fed BOV30 than for heifers fed MON30. Otherwise, differences between the two treatments in DMI, gain to feed, and dietary NE were not statistically significant (p>0.11). Plotting weekly intakes versus THI, observed intake of controls was greater (p<0.05) at THI values ${\leq}77$ than ionophore groups. When THI values were greater than 79, DMI of control and MON30 were not different (p = 0.42), although less than that of groups fed lasalocid (p = 0.04). Variation in energy intake was lower (p>0.05) in the ionophores group (CV = 1.7%) than in the control group (CV = 4.5%). Inclusion of ionophores in the diet resulted in relatively minor changes in carcass characteristics. It is concluded that ionophore supplementation did not exacerbate the decline of DM intake in heat-stressed cattle fed a high-energy finishing diet; on the contrary, it stabilised feed intake and favoured feed efficiency. Ionophore supplementation reduced estimated maintenance coefficients around 10% in finishing cattle during a period of heat stress. This effect was greatest for heifers supplemented with 30 mg lasalocid/kg of diet.

Optimization of Type-2 Fuzzy Logic Controllers for a Non-Rigid Airship Using Clonal Selection Algorithm

Christine Barrera,Ju-Jang Lee 제어로봇시스템학회 2011 제어로봇시스템학회 각 지부별 자료집 Vol.2011 No.12

In the past, non-rigid airship/blimp control was commonly implemented using standard fuzzy logic controllers also known as type-1 fuzzy logic controllers. For better performance, the membership function of the type-1 fuzzy controller was further optimized using different optimization methods with Genetic Algorithm (GA) being the most common. These days, however, a lot of attention is being focused on type-2 fuzzy logic controllers due to its better performance on environments with uncertainties. New optimization methods for the membership function were also being discovered. Among these methods is the Clonal Selection Algorithm (CLONALG) which was inspired from clonal selection principle based on the basic features of an adaptive immune response to an antigenic stimulus. It was proven to have superior performance than Genetic Algorithm because of its faster convergence speed and better fitness values. This method, however, still needs to be tested on an actual control application. This project developed both type-l and type-2 fuzzy logic controllers optimized by using both GA and CLONALG for a blimp control problem. The control system was divided into three parts: velocity, heading and elevation. This research provides a comparison and validates the performance benefits of type-2 over type-1 fuzzy control and CLONALG over GA. A better control with shorter rise time and settling time, less error and less sensitivity to uncertainties was also achieved by using type-2 fuzzy control combined with CLONALG optimization.

A Simple Metabolic Flux Balance Analysis of Biomass and Bioethanol Production in Saccharomyces cerevisiae Fed-batch Cultures

Iliana Barrera-Martinez,R. Axayácatl González-García,Edgar Salgado-Manjarrez,Juan S. Aranda-Barradas 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.1

Production of Saccharomyces cerevisiae yeast for applications in the food industry or in bioethanol production still presents important techno-economic challenges as an industrial bioprocess. Mathematical modeling of cellular metabolism in biological production usually improves process yields, though for industrial applications,the model should be as simple as possible in order to sustain model usefulness and technical feasibility. A comparative analysis between a black box description and a simple metabolic network accounting for the main metabolic events involved in yeast growth and bioethanol production is proposed here. In both cases, a thorough analysis of reaction rates allowed for the ethanol concentrations produced in fed-batch yeast cultures, although our results showed more accurate estimations with the metabolic flux balance methodology. Moreover, an interpretation of the yeast physiological state in fed-batch cultures at different glucose feed concentrations was accomplished by means of a stoichiometric analysis linked to the simplified metabolic network. The results confirmed that increasing glucose uptake rates, controlled mainly by the glucose concentration in the input flow, produced an up-regulation in reductive catabolism, resulting in higher ethanol excretion. The biomass production relied mostly on oxidative catabolism,which is controlled by the glucose and oxygen uptake rates. Thus, ethanol or biomass production is strongly dependent on the physiological state of yeast in the culture, which can be inferred from a suitable metabolic flux balance approach.

The study on the research trend about Europe ports: focus on Baltic Sea using Keyword network

Beatriz Barrera Delgado,마혜민,오재균,여기태 한국디지털정책학회 2018 디지털융복합연구 Vol.16 No.2

Since the 17th century, international trade has increased as a result of the development in the navigation skills. Recently, maritime transport, compared to other modes, is used more than 70% worldwide by shippers and ports, and it also has become essential in international trade. Most researchers focused only on port development, in topics like ensuring depth of water, port competition and port governance, but have left some topics undone, such as environment, ecosystem and balanced development. Therefore, this study provides insight to the academic world in port research using SNA (Social Network Analysis). The result of the SNA study shows that Baltic Sea ports researchers have focused on “Shipping”, “Marine ecosystem”and “Pollution”. The implications of this study are: first, the environment has become a main issue in the research field; second, the results suggest focusing on the main keywords from the keyword network. This study has some limitations such as excluding domestic journals and focusing in the recent 10 years.

Rejection of a kidney graft revealed by positron emission tomography

( Aidana Barrera-herrera ),( Ángela Gonzalez-rojas ),( Andrés Perissinotti ),( Ana Belen Larque ),( Frederic Cofan ),( Fritz Diekmann ),( David Cucchiari ) 대한신장학회 2023 Kidney Research and Clinical Practice Vol.42 No.2

The Dual Drivers in Intuitive Design Thinking: Myself and Making

Bertha Patricia Barrera Garza,James A. Self 한국디자인학회 2023 디자인학연구 Vol.36 No.4

Background : Design thinking is a problem-solving process, currently being used outside of the design domain in workshop format by companies around the world. Although both intuition and making are considered a crucial part in design thinking, little empirical research explores the possibility for making to enhance the application of intuition. In this study, we investigate the role and use of intuition and making in design thinking. Methods : In a controlled, comparative approach, teams participated in guided design thinking workshops. The teams explored a design problem, outlined pain points, and proposed a solution at the end of the workshop. Using independent measures, a control group in the non-making condition followed the traditional design thinking workshop approach, while in a making condition, a making activity was introduced at the start of the workshop using the Lego Serious Play © methodology replacing a graphing activity during the empathy stage, with the rest of the workshop following the traditional design thinking methodology. All workshops were video recorded. An analysis of the recordings was conducted, with time participants engaged making timestamped and compiled. The decisions of each participant were counted and sorted into three types: low, medium, and high-level decisions. High level decisions were used as evidence of the application of intuition. Results : The making activity at the start of the workshop increased the number of high-level decisions in comparison to the non-making condition. The use of Lego in the making condition not only increased the time the participants made but showed that both making and decisions were increasingly distributed across the design thinking workshop. Each participant had a predisposition for the use of their intuition, and by using the Myers Briggs type indicator, intuitive participants were found to have increased high-level decisions. Conclusions : The application of intuitive judgment during design thinking workshops depends upon the individual’s predisposition to use their own intuitions. Opportunity to engage in the making activity also acts as a catalyst for enhancing the use of intuition. To encourage participants of the design thinking workshop to employ their expertise, we suggest making as a driver for experience-based intuitive judgment. For those less inclined to apply intuition, making acts as stimulation. For more intuitive participants, making can enhance their use of intuition.

Characterization of recycled polycarbonate from electronic waste and its use in hydraulic concrete: Improvement of compressive performance

Colina-Martinez, Ana L. De la,Martinez-Barrera, Gonzalo,Barrera-Diaz, Carlos E.,Avila-Cordoba, Liliana I.,Urena-Nunez, Fernando Techno-Press 2017 Advances in concrete construction Vol.5 No.6

Transparency, excellent toughness, thermal stability and a very good dimensional stability make Polycarbonate (PC) one of the most widely used engineering thermoplastics. Polycarbonate market include electronics, automotive, construction, optical media and packaging. One alternative for reducing the environmental pollution caused by polycarbonate from electronic waste (e-waste), is to use it in cement concretes. In this work, physical and chemical characterization of recycled polycarbonate from electronic waste was made, through the analysis by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM). Then cement concrete was made with Portland cement, sand, gravel, water, and this recycled polycarbonate. Specimens without polycarbonate were produced for comparison purposes. The effect of the particle sizes and concentrations of recycled polycarbonate within the concrete, on the compressive strength and density was studied. Results show that compressive strength values and equilibrium density of concrete depend on the polycarbonate particle sizes and its concentrations; particularly the highest compressive strength values were 20% higher than that for concrete without polycarbonate particles. Moreover, morphological, structural and crystallinity characteristics of recycled polycarbonate, are suitable for to be mixed into concrete.