bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploring the Use of Social Media to Advance K12 Science Education
Authors: Ma Jinjin , Chiu Dickson K.W. , Tang Jeff K.T.
Published: February 2017

The astonishing popularity of social media and its emergence into the education arena has shown tremendous potential for innovations in teaching and learning. It enables student-centered learning in a more collaborative and interactive way in the online learning environment. However, few research has been conducted about how to use social media appropriately and effectively in Science education. The main purposes of this project is to explore the experience and perceptions of teachers with relevant teaching experience in using social media for K12 Science education, including the current level and scope of social media use, perception of utility, and its potential impact on science education. The implications, considerations, and challenges for and against the possible use of social media in science education were discussed with possible further research suggestions.
Impact of ICT Usage in Primary-School Students' Learning in The Case of Thailand
Authors: Arukaroon Benjawan , Krairit Donyaprueth
Published: February 2017

The utilization of ICT as a teaching–learning tool continues to be very popular in Thai primary schools. However, technology impact assessments are not always properly carried out, and the benefits of using ICT in primary education are not always clear. The aim of this paper is to assess whether the use of ICT has an impact on student performance compared to when such technology is not used. In the results from the two experimental units, the researchers find no significant effects of ICT usage on student performance either in classroom behaviors or in improvement scores. On further inspection of influential factors for ICT adoption, the results show that only subjective norm has a significant effect on the students' classroom behaviors. In contrast to the previous literature and conventional beliefs, the researchers found that ICT is not always an effective teaching–learning tool regardless of the educational level of students.
Modeling Gender based Customer Preferences of Information Search Channels
Authors: Khatwani Gaurav , Srivastava Praveen Ranjan
Published: February 2017

The disparity in consumer and organization preferences of information channels is a major concern. Further, making decisions in the presence of a wide range of conflicting criteria through the use of a multiple criteria decision-making (MCDM) approach has gained increased prominence in recent years and research in this area has become an important consideration for business operations that involve dealing with complex decision problems. This paper describes how an integrated approach can be applied to a decision-making problem that combines a fuzzy analytical hierarchy process (AHP) and TOPSIS for identifying preferences consumers of information search channels according to demographic factors such as gender.
The Effect of Quenching Temperature and Polishing Force on the Residual Stress and Deformation of Rack Bar Semi-Products
Authors: Majtenyi Jozsef , Benke Márton , Mertinger Valéria , Kazinczi Tímea
Published: February 2017

In the present study, the residual stress state and macroscopic deformation of automotive rack bar semi-products were examined. The rack bars were taken from the original production line after induction hardening, burnishing and polishing. Induction hardening was performed at 860°C, 880°C and 900°C and the polishing step was performed with standard and increased polishing force. Thus, the effect quenching temperature and polishing force are described. Non-destructive residual stress mapping was performed after which macroscopic deformation measurements were carried out on the same rods. It was shown that the variation of quenching temperature had no effect on the residual stress state and deformation of the components. The increased polishing force did not change the average stress state of the rods, however, it resulted in higher stress asymmetry and deformation of the rods. Stress asymmetry was shown to be the cause of bending of the rods.
Non-Destructive Strength Estimation of Lightweight Aggregate Concretes
Authors: Nemes Rita , Simon Tamás K.
Published: February 2017

The porosity, water absorbing capability, internal load bearing system of light weight aggregate concretes differ from ordinary concrete.In case of structural concretes there is often a demand of non-destructive testing, but between the available, connected modifying parameters there are none which are suitable for the special case of light weight aggregate concretes. Particularly big difference in the strength estimation may be observed in case early age concretes, when the moisture content is typically significantly higher than in ordinary concrete.Experiments were executed on structural concretes out of different aggregates (quartz gravel, expanded clay, foamed glass). The tests were carried out at the concretes ages of 3, 7, 28, 91 and 360 days by destructive (cube crushing strength) and two non-destructive testing methods (rebound hammer and ultrasonic). The results are compared and models are drawn.
The Effect of Strain Path Change Form Wire Drawing to Uniaxial Compression in Al0.25Mg Alloy
Authors: Mikó Tamás , Szabó Gábor , Barkóczy Péter
Published: February 2017

In this paper the effect of the strain path change was studied in aluminum alloy containing 0,25% Mg. In metals alloys different metal forming processes can create strong crystallographic and morphologic texture. Both of them can cause direction dependency of the mechanical and other properties. The aim of this paper is to analyze how the effect of the increasing reduction of cold drawn wire appears as a result of the uniaxial compression performed in the direction opposite of drawing. Compression test were performed. Through the results of these tests the changes of the direction of deformations were analyzed qualitatively and numerically. These results provide the possibility to use uniaxial compression test to evaluate the mechanical behavior of cold drawn aluminum.
High Intensity Broad Spectrum LEDs in the Near Infrared Range
Authors: Nádas József , Rakovics Vilmos
Published: February 2017

IR LEDs are widely used in the near-infrared (NIR) spectroscopy, especially in hand-held devices for the detection and measurement of organic materials, allowing faster and cheaper examinations. The -OH, -NH and -CH functional groups found in organic substances can frequently be detected by spectroscopy through absorbance measurement at the resonance wavelength of valence-bond vibrations. The measured wavelengths are 4-2.5 μm, while signal to noise ratio of photon detectors is low due to thermal noise at room temperature. The 1st-3rd harmonic absorption bands are located in the range of the NIR, where smaller signals can be measured effectively in practice. The LEDs have tunable narrow wavelength range therefore they are suitable for such measurements as radiation sources. Further advantages of LEDs compared to incandescent lamps are small dimensions, high efficiency, and low power consumption. In order to tune the emission wavelength of the LED, the composition of the semiconductor light-emitting layer has to be properly set. The change in chemical composition will generally affect the lattice constant too. The crystal defects caused by lattice-mismatch often reduce the efficiency. The emission wavelength is tunable in the quaternary GaInAsP/InP material system meanwhile the lattice-constant remains unchanged. Absorption band of the organic materials is generally broader than the emission spectrum of the LED, therefore a broader emitter is preferred. To achieve this, a number of solutions are known. One of these is to use multiple layers with different composition, where the primary light comes from the active layer at the p-n junction of the diode, then excites the second smaller band gap layer producing longer wavelength secondary light by photoluminescence. The transmitted part of the primary light, together with the secondary light, results in a broader spectrum. This method is not yet implemented in this material system, so my work is focused mainly on this approach.
The Role of the Technological Residual Stress in Spiral Bevel Gears’ Degradation
Authors: Angel Dávid , Benke Márton , Mertinger Valéria
Published: February 2017

The subjects of the examination were automotive components, spiral bevel gears, built up by two main parts, the axle, where the component is prone to fracture, and the head segment, where the working surface can be found. The occasional fracture occurs during the straightening process after the hardening heat treatment. Our aims were to monitor the evolution of the residual stress during the manufacturing processes and to reveal the role of the residual stress in the component’s fracture. The residual stress measurements were carried out via non-destructive X-ray diffraction. To reveal the component’s fracture hardness tests and microstructure measurements were also performed. Based on the results, the fracture of the components were connected to the stress asymmetry which was derived from the microstructure of the early stages of manufacturing.
Microstructure and Texture Evolution in Cladded Al 3003 Aluminum Sheets
Authors: Hlavacs Adrienn , Benke Márton , Barkóczy Péter , Mertinger Valéria
Published: February 2017

In the present research, the texture variation during cold rolling of cladded 3003 type aluminium sheets was examined by means of X-ray diffraction. The aluminum sheets were formed in a series of 14 rolling steps, after which texture examinations were performed on both cladded and base material sides of the sheets. After certain rolling steps, the texture was also examined by removing layers from the sheets by electropolishing to reveal the texture distribution along depth. The texture was characterised through the calculation of volume fractions of the main rolled texture components. Local drawbacks were found in the texture versus thickness reduction function. The texture was found to be higher in the middle of the sheets than at the surface.
Examination of the Properties of Resin Bonded Core Mixtures
Authors: Mikóné Mádi Laura , Varga László , Mikó Tamás
Published: February 2017

The production technology for automotive foundry castings has developed significantly during the past decade. The production of cylinder hats with more and more complex designs could be rather challenging for core makers. Heating might cause the annealing of the core, thus, the buoyancy of the molten metal increases which might cause the movement of the core. The heat distortion of the cores was examined with a Hot Distortion Tester. A universal Instron 5982 device was used for bending, wedge penetration strength and cold and hot compression tests. The test bars were prepared with cold- and hot-box processes using DMPA (Dimethylpropyl-amine) under laboratory conditions. The tests showed that the decrease of the bending strength is proportional to the amount of additives. The compression test results showed that the test bars produced with cold-box compression have the lowest and the ones with furan resin mixtures have the highest compressive strength.
Corrosion Resistance of TIG Welded Joints of Stainless Steels
Authors: Alcantara Amanda Silveira , Fábián Enikő Réka , Furkó Monika , Fazakas Éva , Dobránszky János , Berecz Tibor
Published: February 2017

The aim of this work was to analyze the performance of joints made by TIG (Tungsten Inert Gas) welding process in austenitic and duplex stainless steels with special regards to their corrosion resistance. Three different types of stainless steel were butt welded with TIG method. Ferric-chloride test and electrochemical treatments revealed how does the TIG process affects the corrosion resistance depending upon the alloy used for welding the joint. This work focuses on the weldability of the 2304, 2404 and 304 type stainless steel heterogeneous welds.
Characterization of Internal Stresses in Hybrid Steel Structures Produced by Direct Metal Laser Sintering
Authors: Hatos István , Hargitai Hajnalka , Kovács József Gábor
Published: February 2017

In this study hybrid structure were produced by direct metal laser sintering of maraging steel (MS1) powder onto the surface of commercial mold steels. The over-sintering method should be analyzed to find the optimum pre-and post-heat treatment to minimize the internal stresses. The internal stress is directly proportional to the deformation if the solid thick part is reduced to thin plate like parts. Based on this recognition the deformation of the plates over-sintered with MS1 could be analyzed in order to explore the internal stresses and the effect of different pre-and post-heat treatments were examined.
Nanostructure Growth Supported by In Situ RHEED Evaluation
Authors: Kucsera Péter , Sándor Tamás , Tényi Gusztáv Varga , Csutorás Márton , Bátori Gergely , Kupás-Deák Béla , Réti István , Ürmös Antal , Nemcsics Ákos
Published: February 2017

The in-situ monitoring of the MBE grown nanostructures can be carried out using the RHEED method. During the droplet epitaxal growth, the observation of the nanostructure formation is very important to understand the growth kinetics. In the present work, a novel in-situ RHEED evaluation and further MBE related developments are introduced, with which the quality of the nanostructure preparation can be improved.
Set Point Based Material Selection Method in Case of Recycled Polypropylene Application
Authors: Czél György , Zattler Mate
Published: February 2017

Due to the economic reasons of the injection moulding process, robust technology set point was given in the case of a polypropylene part manufacturing. The part, named lid plate was a relatively humble product not sensitive for small strength parameter changing. K392 coded polypropylene (PP) was given as reference raw material for injection moulding. The technical task was to replace the reference material by using recycled PP. It was necessary to keep the production cycle term. The flow characteristics of the offered recycled polymers were previously unknown. New method and capillary rheometry experimental technique was used to aid the material selection. In the method, the repeatability and the accuracy of rod type capillary rheometry was investigated in order to get more reliable flow behavior data of recycled PP polymer. Relatively low repeatability deviance could be determined in the range of 800-1100 s-1 shear rate range by using rod capillary rheometry. By means of the adequate validated rheometry, the recycled polypropylene could be applied for the given technology set point based forming process.
Investigation of Morphology of Recycled PET by Modulated DSC
Authors: Molnar Bela , Ronkay Ferenc
Published: February 2017

During research injection molded samples were made from recycled poly (ethylene terephthalate) (PET). Morphological properties of samples were investigated by modulated differential scanning calorimetry (MDSC). Total heat flow was separated in two parts, reversing and non-reversing heat flow during measurements. Relationships were found between crystallization and melting processes: the initial crystallinity equals to the non-reversing melting, and the post-crystallization processes equals to reversing melting.
Failure Analysis of Aluminum – Ceramic Composites
Authors: Kozma István , Fekete Imre , Zsoldos I.
Published: February 2017

The increasingly widespread use of syntactic metal foams is due to their excellent energy absorbing characteristics. Several research groups deal with developing methods that can further improve this characteristic. Several literature analyses have been devoted to the effects of materials selection, cell size and wall thickness of the reinforcing element on the compression strength. In this work an in situ test necessary for the modeling of the failure process introduced. The aluminum-ceramic composite foams were cyclically upset. The geometry of the test specimen was reconstructed at a certain point of the compression test by μCT technology and digital image analysis. The failure process was characterized by volume change, by the number of broken shells and by the formation of shear plane as a function of the deformation.
Hybrid Thermoset Matrix Carbon Fibre Reinforced Composites, a Study of Interlaminar Properties
Authors: Turcsán Tamás , Mészáros László
Published: February 2017

In this study carbon fibre reinforced epoxy, unsaturated polyester, and vinyl ester based, binary (two-component) hybrid matrix polymer composites were produced and mechanically characterized by interlaminar shear tests. Fracture surface of tested composites were investigated by scanning electron microscopy. Toughness of hybrid matrix composites were identified and compared to that of the reference, non-hybrid matrix ones.
Development of Microcapsules
Authors: Vermes Brúnó , Czigány Tibor
Published: February 2017

Melamine-formaldehyde (PMF) coated microcapsules were produced with liquid pentaerythritol-tetrakis (3-merkaptopropionate) (PETMP) and UV-sensitive indicator colored PETMP cores. Capsules with an average diameter of 43 μm formed due to the adjustments on magnetic stirring, compound ratios, acidity and reaction time. Reproducible recipe was found to produce colored PETMP filled capsules with yields of 1-10%. Optical microscopic investigations were conducted to follow the formation of the particles, and scanning electron-microscope (SEM) was used to verify that the capsules did not break up as an effect of the brittle failure of the epoxy matrix specimens. Improvement of the shell-matrix adhesion was attempted with silane compounds and investigated with X-ray photoelectron spectroscopy (XPS) and SEM.
Development of Glass Matrix for Radioactive Waste Conditioning
Authors: Fábián Margit , Araczki Csaba
Published: February 2017

Understanding of the incorporation of actinides in borosilicate matrix used for nuclear waste storage is of a great importance for radioactive waste immobilization. This study carried out on matrix glasses doped respectively with 30wt% UO3 and CeO2, Nd2O3 used for chemical modelling of the actinides. Neutron and X-ray diffraction measurements and Reverse Monte Carlo (RMC) simulations were performed. For several glasses, it was found that the basic network structure consists of tetrahedral SiO4 units and of mixed trigonal BO3 and tetrahedral BO4. The BO3 and BO4 units are linked to SiO4, forming mixed [4]Si-O-[3]B and [4]Si-O-[4]B bond-linkages. From significant second neighbour atomic pair correlations have been revealed that U, Ce, Nd accommodates in both silicate and borate site.
Correlation between Microstructure and Hydrogen Storage Properties of Nanocrystalline Magnesium Subjected to High-Pressure Torsion
Authors: Revesz Adam , Gajdics Marcell
Published: February 2017

High-pressure torsion was performed on commercial magnesium disks under uniaxial compression and simultaneously shear straining for different number of turns. Microstructural evolution during the severe plastic deformation process has been investigated by X-ray diffraction line profile analysis. Complementary hydrogen absorption experiments in a Sieverts’-type apparatus indicated that hydrogen storage and the microstructural parameters exhibit correlation.
Electrochemical and Morphological Characterization of Silver Doped Bioceramic Layer on Metallic Implant Materials for Orthopaedic Application
Authors: Furkó Monika , Fazakas Éva , Fábián Enikő Réka , Balázsi Csaba
Published: February 2017

This study presents the production of silver doped bioactive calcium-phosphate (CaP) coatings on commonly used orthopaedic implant materials (Ti6Al4V). The deposition process was performed by pulse current technique from electrolyte containing the appropriate amount of Ca(NO3)2 and NH4H2PO4 components at 70 °C. In order to modify the CaP layer, Ag+ ions were added to the base electrolyte. The electrochemical behaviour of the coatings was investigated by potentiodynamic polarization method in conventional Ringer’s solution in a three-electrode open cell. The corrosion properties of samples prepared with different parameters were compared. During immersion, the coating comes into contact with the electrolyte and corrosion occurs. Due to the potential difference between layer and the metallic substrate, discrete anodic and cathodic areas can be formed, which result in the release of silver and calcium ions. For antimicrobial applications of the modified CaP coated implant alloys, it is important to maintain a continuous release of silver ions, while the bioactive CaP layer enhance the biocompatibility properties of the layer by fostering the bone cell growth. The morphology and grain size of coatings as deposited have been investigated and confirmed by different methods such as Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray (EDX) analysis.
Investigation of Local Corrosion Degradation Developed on a Pipeline System in Service Period
Authors: Trampus Peter , Fábián Enikő Réka , Kerner Zsolt , Lakatos-Varsányi Magda , Péter László , Réger Mihály , Szabó Péter János , Telegdi Judit , Verő Balázs
Published: February 2017

Corrosion degradation was observed in a nuclear power plant spent fuel cooling system. A systematic and comprehensive investigation program was developed which was negatively influenced by the limit of sampling (contaminated material). Corrosion tests, mechanical and microstructural investigations were carried out and also microbiological effect was examined. Major contributors to the degradation were identified.
R2C2 in Action: Testing an Evidence-Based Model to Facilitate Feedback and Coaching in Residency
Authors: Sargeant Joan , Mann Karen , Manos Sarah , Epstein Ian , Warren Andrew , Shearer Cindy , Boudreau Michelle
Published: February 2017

Background

Feedback is increasingly seen as a collaborative conversation between supervisors and learners, where learners are actively and reflectively engaged with feedback and use it to improve. Based on this, and through earlier research, we developed an evidence- and theory-informed, 4-phase model for facilitating feedback and practice improvement—the R2C2 model (relationship, reaction, content, coaching).

Objective

Our goal was to explore the utility and acceptability of the R2C2 model in residency education, specifically for engaging residents in their feedback and in using it to improve, as well as the factors influencing its use.

Methods

This qualitative study used the principles of design research. We recruited residents and their supervisors in 2 programs, internal medicine and pediatrics. We prepared supervisors to use the R2C2 model during their regular midrotation and/or end-of-rotation feedback sessions with participating residents to discuss their progress and assessment reports. We conducted debriefing interviews with supervisors and residents after each session. We analyzed transcripts as a team using template and content analysis.

Results

Of 61 residents, 7 residents (11%) participated with their supervisors (n = 5). Schedules and sensitivity to feedback prevented broader enrollment. Supervisors found the structured R2C2 format useful. Residents and supervisors reported that the coaching phase was novel and helpful, and that the R2C2 model engaged both groups in collaborative, reflective, goal-oriented feedback discussions.

Conclusions

Participants found that using the R2C2 model enabled meaningful feedback conversations, identification of goals for improvement, and development of strategies to meet those goals.
Estrutura e distribuição espacial da vegetação da Caatinga na Estação Ecológica do Seridó, RN
Authors: Santana José Augusto Da Silva , Santana Júnior José Augusto Silva , Barreto Wanctuy Da Silva , Ferreira Anderson Targino Da Silva
Published: February 2017

Este trabalho descreve a estrutura e o padrão de distribuição espacial das espécies do estrato arbóreo-arbustivo na Caatinga da Estação Ecológica do Seridó, no Município de Serra Negra do Norte, RN. Foram amostrados os indivíduos com diâmetro ao nível do solo ≥ 3 cm e altura total ≥ 1 m, presentes em 30 parcelas de 200 m2. O padrão de distribuição espacial foi determinado pelo índice de Payandeh. Registraram-se 2.448 indivíduos, distribuídos em 22 espécies, 20 gêneros e 12 famílias. A densidade foi de 4.080 indivíduos ha-1 e área basal de 17,50 m2 ha-1, enquanto a altura e o diâmetro médios atingiram 2,45 m e 6,80 cm, respectivamente. As famílias com maior número de espécies foram Fabaceae e Euphorbiaceae, com destaque em número de indivíduos para Euphorbiaceae, Fabaceae e Apocynaceae. Poincianella pyramidalis, Aspidosperma pyrifolium e Croton blanchetianus foram as espécies mais importantes, respondendo juntas pelo maior número de indivíduos, área basal e valor de importância. A área estudada apresenta pouca evidência de perturbação antrópica, com estrutura semelhante a outras áreas protegidas na Caatinga do Seridó e com maior proporção de espécies com distribuição agregada ou com tendência à agregação, revelando que as maiores populações formam pequenos agrupamentos.
Parâmetros morfométricos e biológicos de populações monoclonais e multiclonais do pulgão-gigante-do-pinus
Authors: Penteado Susete Do Rocio Chiarello , Noemberg Lazzari Sonia Maria , De Oliveira Edilson Batista , Zonta de Carvalho Regina Celia
Published: February 2017

O pulgão-gigante-do-pinus, Cinara atlantica, originário da América do Norte, foi introduzido no Brasil na década de 1990 e encontra-se amplamente distribuído nos plantios comerciais de pínus. Este estudo teve como objetivo correlacionar os parâmetros morfométricos de insetos oriundos de colônias mono e multiclonais de C. atlantica com seu desempenho reprodutivo em mudas de viveiros comerciais e em progênies de Pinus taeda. Foi registrado o número de ninfas produzidas fêmea dia-1. Após a morte destas fêmeas, foram realizadas medições dos caracteres morfológicos, utilizando o programa, Axion Vision 4,5. O comprimento da tíbia, fêmur posterior e antena foram os parâmetros morfométricos que apresentaram maior correlação com o comprimento do corpo dos insetos, representando 98% da variação total. Com os valores destas variáveis foi criada uma nova variável, denominada “tamanho do inseto”, que foi utilizada para comparação dos tratamentos. Os insetos de colônias multiclonais apresentaram os maiores valores para a maioria dos parâmetros morfométricos e maior produção de descendentes. Insetos maiores e maior produção de ninfas foram observados em mudas originárias dos viveiros comerciais, sugerindo que as progênies estudadas podem apresentar algum fator de resistência que as torna candidatas para uso em programas de manejo integrado desta praga.
Tratamento térmico da madeira em atmosfera de glicerina
Authors: Pertuzzatti Anderson , Missio André Luiz , Gatto Darci Alberto , Farias Jorge Antônio , Haselein Clovis Roberto
Published: February 2017

O presente estudo visou avaliar tratamentos térmicos na madeira sob atmosfera de glicerina, que é resíduo da indústria de biodiesel, além de direcionar o produto obtido para os nichos de mercado da indústria madeireira. Foram selecionadas seis árvores de Eucalyptus grandis e E. cloeziana provenientes de plantios homogêneos com 21 anos. Dessas, foram confeccionados os corpos de prova e encaminhados para um banho de óleo laboratorial contendo glicerina bruta pré-aquecida a 50 °C. Os tratamentos consistiram no aquecimento da madeira em atmosfera de glicerina a 125 °C e 165 °C, por 30 min, além das amostras controle. Na sequência, foi quantificada a variação percentual de massa, o teor de umidade de equilíbrio e a absorção máxima de água. Ainda, foram quantificados os parâmetros colorimétricos, conforme o sistema CIEL*a*b*. Foi utilizado delineamento inteiramente casualizado, com duas temperaturas, e o tratamento controle. A utilização da glicerina na termorretificação reduziu o teor de umidade de equilíbrio e provocou o escurecimento superficial da madeira. Entretanto, a madeira tratada apresentou restrições de uso em contato com a água, podendo ser utilizada em ambientes internos.
Avaliação econômica de projetos de sistemas agroflorestais
Authors: Cosenza Diogo Nepomuceno , Oliveira Neto Silvio Nolasco de , Jacovine Laércio Antônio Gonçalves , Rodrigues Caroline Ribeiro , Rode Rafael , Soares Vicente Paulo , Leite Helio Garcia
Published: February 2017

Por se tratar de uma atividade complexa, os estudos de viabilidade econômica de sistemas agroflorestais (SAFs) exigem maior esforço para avaliação. Dentre os motivos estão a maior quantidade de elementos a serem considerados, a necessidade de prever os efeitos das interações entre as diferentes espécies consorciadas e a dificuldade de valorar os benefícios ambientais do sistema. Dessa forma, o objetivo deste trabalho foi analisar e sintetizar os principais métodos de avaliação econômica descritos na literatura. Através dele é possível determinar quais itens devem ser computados na análise e como atribuir valores a eles para definir as principais receitas e custos do projeto. Ainda, podem ser traçados os principais métodos de análise econômica e de comparação de resultados. Por fim, entende-se que existem dificuldades na valoração de muitos benefícios que os SAFs proporcionam, mas estas podem ser contornadas pelas metodologias apresentadas. Além disso, criou-se a necessidade de promover os benefícios ambientais (externalidades) do sistema, a fim de valorizar os seus serviços frente ao mercado.
Ecologia do fogo e o impacto na vegetação da Amazônia
Authors: Liesenfeld Marcus Vinicius Athaydes , Vieira Gil , Miranda Ires Paula de Andrade
Published: February 2017

O objetivo desta revisão é apontar alguns campos de investigação atuais em ecologia do fogo e os impactos do fogo na vegetação da Amazônia. A ocorrência de incêndios na Amazônia úmida parecia uma contradição até bem pouco tempo. O fogo é independente da existência de humanos e o mesmo sempre atuou na estruturação da vegetação. Entretanto hoje, com as anomalias e as mudanças climáticas globais, os regimes de fogo têm se alterado em todo o mundo e também na Amazônia. O fogo impacta de forma diferente, dependendo da região amazônica em que ocorre, e isso pode estar relacionado ao solo, bem como à morfologia e idade das plantas. Muitas espécies podem responder de forma positiva, possuindo mecanismos de sobrevivência ou rebrote pós-fogo. É necessária uma melhor compreensão de como as plantas da Amazônia respondem ao impacto do fogo, no sentido de entender o quanto a floresta tropical Amazônica ainda é de fato imune aos incêndios, e de que modo o fogo poderia contribuir com a chamada “savanização” da Amazônia.
Resistência natural da madeira de Tachigali vulgaris ao fungo xilófago Postia placenta
Authors: Stallbaun Patricia Hellenn , Baraúna Edy Eime Pereira , Monteiro Thiago Campos , Vieira Renato Silva , Sales Nilza De Lima Pereira , Oliveira Leandro Silva
Published: February 2017

O trabalho teve como objetivo analisar a resistência natural da madeira de Tachigali vulgaris L. G. Silva & H. C. Lima ao fungo Postia placenta (Fr.) M. J. Lars. & Lomb., causador da podridão parda. Foram coletadas nove árvores e, da tora basal, confeccionadas seis amostras de cada indivíduo, com dimensões de 25 mm x 25 mm x 9 mm (radial, tangencial e axial) no sentido base ao topo. As amostras foram mantidas em contato com o fungo durante 14 semanas, em sala climatizada, sendo posteriormente secas e a perda de massa avaliada. A madeira de T. vulgaris se mostrou altamente resistente a P. placenta, pois o maior valor de perda de massa foi de 12,13%. Foi observada correlação indireta de 82,9% entre a densidade básica e a durabilidade da madeira, porém não foi constatada influência das posições no sentido base topo na durabilidade.
Substratos renováveis na produção de mudas de Ficus enormis proveniente de jardim clonal
Authors: De Oliveira Fragoso Rosimeri , Stuepp Carlos André , Carpanezzi Antonio Aparecido , Wendling Ivar , Zuffellato-Ribas Katia Christina , Soares Koehler Henrique
Published: February 2017

Objetivou-se avaliar substratos renováveis à base de casca de arroz carbonizada (CAC) e fibra de coco (FC) sobre o enraizamento e qualidade final de mudas de Ficus enormis Mart. ex Miq. via estaquia caulinar de plantas provenientes de jardim clonal. Foram avaliados seis substratos: comercial (controle), composto por casca de arroz carbonizada (CAC), fibra de coco (FC) e vermiculita (S1); 100% FC (S2); 100% CAC (S3); 50% FC e 50% CAC (S4); 30% (FC) e 70% CAC (S5); 70% FC e 30% CAC (S6). O substrato comercial (S1) e as composições com maior proporção de FC apresentam qualificação superior para a produção de mudas de F. enormis.
Sazonalidade da umidade de equilíbrio da madeira para o Estado de Mato Grosso
Authors: Souza Adilson Pacheco de , Stangerlin Diego Martins , Melo Rafael Rodolfo de , Uliana Eduardo Morgan
Published: February 2017

Por ser um material orgânico, heterogêneo e higroscópico, a madeira pode apresentar variações dimensionais e deformações decorrentes da interação com o ambiente. Em uso ou nos processos de secagem, quando são atingidos os equilíbrios entre a madeira e o ar atmosférico, têm-se a obtenção da umidade de equilíbrio da madeira (UEM). Em função da elevada importância dessa matéria-prima para o Estado de Mato Grosso, torna-se fundamental conhecer a sazonalidade de UEM. O presente trabalho objetivou estimar a UEM da madeira, pelo modelo de Simpson, para 30 municípios do Estado de Mato Grosso, distribuídos nas diferentes regiões de planejamento do Zoneamento Sócio-Econômico Ecológico do Estado. Os dados meteorológicos foram obtidos da Rede de Estações Meteorológicas Automáticas do Instituto Nacional de Meteorologia, entre 2006 e 2012. A UEM foi estimada diariamente, com posterior obtenção das médias mensais. Na estação seca ocorreram variações da UEM entre 5,08 e 9,57% e no período chuvoso entre 8,58 e 13,49%. Nos meses de janeiro, fevereiro e março ocorrem os maiores valores de UEM no estado. As condições ambientais durante o período seco (julho a setembro) favorecem a secagem natural da madeira serrada, por condicionarem uma secagem mais rápida.
Densidade energética de briquetes de biomassa lignocelulósica e sua relação com os parâmetros de briquetagem
Authors: Souza Frederico De , Vale Ailton Teixeira do
Published: February 2017

A densidade energética é uma das principais propriedades que definem a qualidade do briquete, pois resume as características químicas, as condições de umidade e a quantidade de calor do produto final em uma única variável. Para analisá-la, foram confeccionados seis briquetes por tratamento (pinus, tauari, cumaru, casca de arroz, bagaço de cana e torta de pinhão manso) em uma prensa briquetadeira Lippel modelo LB-32 com 40 g de biomassa cada e 5 min de prensagem. Os parâmetros de briquetagem foram: duas temperaturas (130 e 200 ºC), duas pressões de compactação (80 e 120 kgf cm-²) e dois tamanhos de partículas (grossas – retidas em peneira 35 mesh; finas – não retidas a 35 mesh). A densidade energética foi obtida multiplicando-se o poder calorífico útil pela densidade aparente. Adicionalmente, realizou-se a análise química imediata. Os resíduos florestais tiveram o carbono fixo 9,0% superior e cinzas 2,3% inferior, comparados aos resíduos agrícolas. A densidade aparente dos briquetes variou de 1,088 a 1,305 g cm-³ e a densidade energética entre 3,11 – 4,67 Gcal m-³. Os briquetes de cumaru foram considerados de melhor qualidade, com densidades aparente e energética de 1,23 g cm-³ e 4,61 Gcal m-³, respectivamente. Concluiu-se que o efeito da temperatura favoreceu a qualidade do briquete, superando os efeitos da pressão de compactação e tamanho da partícula.
Fire passage on geomorphic fractures in Cerrado: effect on vegetation
Authors: Santana Otacílio Antunes , Encinas José Marcelo Imaña , Silveira Flávio Luiz de Souza
Published: February 2017

A fratura geomórfica é uma formação geológica natural, que em alguns casos forma uma fissura profunda na rocha, com o estabelecimento de solo e vegetação. O objetivo desse trabalho foi analisar a vegetação dentro das fraturas geomórficas sobre o efeito da passagem do fogo. Para isso, as seguintes variáveis biométricas foram avaliadas: diâmetro, altura, índice de área foliar, volume de madeira, biomassa herbácea, número de indivíduos e de espécies arbóreas e arbustivas, antes e depois da passagem do fogo. Esses dados foram comparados com as áreas adjacentes às fraturas (controle). O efeito da passagem do fogo sob a vegetação dentro da fratura geomórfica não foi significativa, pois o fogo seguiu a superfície do solo (cama de fogo formada pela biomassa das plantas) e quando encontrou com a fratura (mais úmida) mudou da superfície do solo para o dossel (pelo efeito de saltar do fogo), afetando não significativamente o número de indivíduos e espécies vegetais; então, a fratura poderia ser um refúgio para as plantas contra a passagem do fogo. Pode-se inferir em nosso modelo experimental de que a qualidade da cama de biomassa vegetal poderia ser mais importante do que a quantidade, e a variabilidade do microclima recruta as plantas para o refúgio (fratura geomórfica).
Constraining the ship contribution to the aerosol of the central Mediterranean
Authors: Becagli Silvia , Anello Fabrizio , Bommarito Carlo , Cassola Federico , Calzolai Giulia , Di Iorio Tatiana , di Sarra Alcide , Gómez-Amo José-Luis , Lucarelli Franco , Marconi Miriam , Meloni Daniela , Monteleone Francesco , Nava Silvia , Pace Giandomenico , Severi Mirko , Sferlazzo Damiano Massimiliano , Traversi Rita , Udisti Roberto
Published: February 2017

Abstract. Particulate matter with aerodynamic diameters lower than 10 µm, (PM10) aerosol samples were collected during summer 2013 within the framework of the Chemistry and Aerosol Mediterranean Experiment (ChArMEx) at two sites located north (Capo Granitola) and south (Lampedusa Island), respectively, of the main Mediterranean shipping route in the Straight of Sicily. The PM10 samples were collected with 12 h time resolutions at both sites. Selected metals, main anions, cations and elemental and organic carbon were determined. The evolution of soluble V and Ni concentrations (typical markers of heavy fuel oil combustion) was related to meteorology and ship traffic intensity in the Straight of Sicily, using a high-resolution regional model for calculation of back trajectories. Elevated concentration of V and Ni at Capo Granitola and Lampedusa are found to correspond with air masses from the Straight of Sicily and coincidences between trajectories and positions of large ships; the vertical structure of the planetary boundary layer also appears to play a role, with high V values associated with strong inversions and a stable boundary layer. The V concentration was generally lower at Lampedusa than at Capo Granitola V, where it reached a peak value of 40 ng m−3. Concentrations of rare earth elements (REEs), La and Ce in particular, were used to identify possible contributions from refineries, whose emissions are also characterized by elevated V and Ni amounts; refinery emissions are expected to display high La ∕ Ce and La ∕ V ratios due to the use of La in the fluid catalytic converter systems. In general, low La ∕ Ce and La ∕ V ratios were observed in the PM samples. The combination of the analyses based on chemical markers, air mass trajectories and ship routes allows us to unambiguously identify the large role of the ship source in the Straight of Sicily. Based on the sampled aerosols, ratios of the main aerosol species arising from ship emission with respect to V were estimated with the aim of deriving a lower limit for the total ship contribution to PM10. The estimated minimum ship emission contributions to PM10 were 2.0 µg m−3 at Lampedusa and 3.0 µg m−3 at Capo Granitola, corresponding with 11 and 8.6 % of PM10, respectively.
Net ecosystem exchange and energy fluxes in a West Siberian bog
Authors: Alekseychik Pavel , Mammarella Ivan , Karpov Dmitry , Dengel Sigrid , Terentieva Irina , Sabrekov Aleksander , Glagolev Mikhail , Lapshina Elena
Published: February 2017

Abstract. Very few studies of ecosystem-atmosphere exchange involving eddy-covariance data have been conducted in Siberia, and none in West Siberia. This work provides the first estimates of carbon dioxide (CO2) and energy budgets at a typical bog of the West Siberian middle taiga based on May-August measurements in 2015. The footprint of measured fluxes consisted of homogeneous mixture of tree-covered ridges and hollows with the vegetation represented by typical sedges and shrubs. Generally, the surface exchange rates resembled those of pine-covered bogs elsewhere. The surface energy balance closure was 90 %. Net CO2 uptake was comparatively high, summing up to 196 gC m−2 for the four measurement months, while the Bowen ratio was typical at 30 %. The ecosystem turned into a net CO2 source during several front passage events in June and July. Several periods of heavy rain helped keep the water table at a constant level, preventing a usual drawdown in summer. However, because of the cloudy and rainy weather, the observed fluxes might rather represent the special weather conditions of 2015 than their typical level.
Target categorization of aerosol and clouds by continuous
multiwavelength-polarization lidar measurements
Authors: Baars Holger , Seifert Patric , Engelmann Ronny , Wandinger Ulla
Published: February 2017

Abstract. Absolute calibrated signals at 532 and 1064 nm and the depolarization ratio from a multiwavelength lidar are used to categorize primary aerosol but also clouds in high temporal and spatial resolution. Automatically derived particle backscatter coefficient profiles in low temporal resolution (30 min) are applied to calibrate the lidar signals. From these calibrated lidar signals, new atmospheric parameters in temporally high resolution (quasi particle backscatter coefficient) are derived. By using thresholds obtained from multi-year, multi-site EARLINET measurements, four aerosol classes (small; large, spherical; large, non-spherical; mixed, partly non-spherical) and several cloud classes (liquid, ice) are defined. Thus, particles are classified by their physical feature (shape and size) instead of a classification by source. The methodology is applied to two months of continuous observations (24 hours, 7 days a week) with the multiwavelength-Raman-polarization lidar PollyXT during the HOPE campaign in spring 2013. Cloudnet equipment was operated continuously directly next to the lidar and is used for comparison. By discussing three 24-h case studies, it is shown that the aerosol discrimination is very feasible and informative and gives a good complement to the Cloudnet target categorization. By analyzing the entire HOPE campaign, almost 1 million pixel (5 min times 30 m) could be successfully classified from the two months data set with the newly developed tool. We find that the majority of the aerosol, trapped in the planetary boundary layer (PBL), were small particles as expected for a heavily populated and industrialized area. Large, spherical aerosol was observed mostly at the top of the PBL and close to the identified cloud bases indicating the importance of hygroscopic growth of the particles at high relative humidity. Interestingly, it is found that on several days non-spherical particles were dispersed into the atmosphere from ground.
Physiological response of a golden tide alga (Sargassum muticum) to the interaction of ocean acidification and phosphorus enrichment
Authors: Xu Zhiguang , Gao Guang , Xu Juntian , Wu Hongyan
Published: February 2017

Abstract. The development of golden tides is potentially influenced by global change factors, such as ocean acidification and eutrophication, but related studies are very scarce. In this study, we cultured a golden tide alga, Sargasssum muticum, at two levels of pCO2 (400 and 1000 µatm) and phosphate (0.5 and 40 µM) to investigate the interactive effects of elevated pCO2 and phosphate on the physiological properties of the thalli. Higher pCO2 and phosphate (P) levels alone increased the relative growth rate by 41 and 48 %, the net photosynthetic rate by 46 and 55 %, and the soluble carbohydrates by 33 and 62 %, respectively, while the combination of these two levels did not promote growth or soluble carbohydrates further. The higher levels of pCO2 and P alone also enhanced the nitrate uptake rate by 68 and 36 %, the nitrate reductase activity (NRA) by 89 and 39 %, and the soluble protein by 19 and 15 %, respectively. The nitrate uptake rate and soluble protein was further enhanced, although the nitrate reductase activity was reduced when the higher levels of pCO2 and P worked together. The higher pCO2 and higher P levels alone did not affect the dark respiration rate of the thalli, but together they increased it by 32 % compared to the condition of lower pCO2 and lower P. The neutral effect of the higher levels of pCO2 and higher P on growth and soluble carbohydrates, combined with the promoting effect on soluble protein and dark respiration, suggests that more energy was drawn from carbon assimilation to nitrogen assimilation under conditions of higher pCO2 and higher P; this is most likely to act against the higher pCO2 that caused acid–base perturbation via synthesizing H+ transport-related protein. Our results indicate that ocean acidification and eutrophication may not boost golden tide events synergistically, although each one has a promoting effect.
A reconstruction of 1 August 1674 thunderstorms over the Low Countries
Authors: van der Schrier Gerard , Groenland Rob
Published: February 2017

Abstract. On 1 August 1674 an active cold front moved over the Low Countries. The accompanying thunderstorms along the squall line were abnormally active, leading to large-scale damage in Europe, from northern France to the northern parts of Holland where damages were particularly severe. Using reported and pictured observations of damages and modern meteorological concepts, the reconstruction of the storm points to an exceptionally severe squall line. The orientation and the velocity of the squall line are reconstructed and shows a developed bow-echo structure. An estimate of the strength of the strongest wind gusts is ≈ 55–90 m s−1 and is based on an assessment of the damages caused by this event. A rough estimate of the return time of this event, based on observed hail size, is between 1000 and 10 000 years. This storm is compared to a more recent storm which was similar in dynamics but much less devastating. Special attention is given to the city of Utrecht which was hit hardest, and where the impact of this storm is still recognizable in the cityscape.