Influence of crumb rubber gradation on asphalt-rubber properties

Asphalt rubber is a material produced by the incorporation of crumb rubber obtained from ground tires in straight asphalt and its properties are influenced by the components properties. The crumb rubber gradation is one of the variables which have a significant influence on asphalt rubber properties. Thus, this work studies the influence of crumb rubber gradation on the asphalt rubber properties expressed by penetration, rotational viscosity (using the Brookfield viscometer), resilience and softening point. Test samples were produced with a 50/70 penetration grade straight asphalt and a crumb rubber obtained by the grinding process which basically consists in a tearing and crushing the old tires at ambient temperature. The digestion time was 60 minutes and the digestion temperature was 170 ºC. The results show that the rotational viscosity and the resilience are the properties most affected by the crumb rubber. It was also observed that the increase of the crumb rubber specific surface (fine crumb rubber) produces asphalt rubber with higher viscosity and lower resilience. The use of coarse crumb rubber influences mainly the resilience.Brasil. Ministério da Educação. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ)

Comportamento produtivo da goiabeira sob irrigacao no vale do rio Moxoto. I. Variedades industriais: onze anos de producao.

Objetivando-se caracterizar o comportamento produtivo de plantas selecionadas de goiabeira, para fins industriais, foi efetuado na regiao do Rio Moxoto em Ibimirim, PE, um estudo com quinze plantas, incluindo variedades e selecoes. Foram observados a producao por planta, o numero de frutos colhidos no periodo de 1977 a 1987, bem como a distribuicao das safras durante o periodo de 1982 a 1987. Verificou-se que o material selecionado e cultivado sob regime de irrigacao, apresenta excelentes niveis de producao, que variam de 96,2 a 176,2 kg/ano, em media de onze anos de observacao. Ficou caracterizado, tambem, a ocorrencia de duas safras/ano, com periodo de entressafra concentrado entre maio e junho

Desempenho do distrito de irrigação Senador Nilo Coelho.

A global and quantitative approach was used to describe and evaluate performance indicators aimed at guiding interventions for the improvement of performance in irrigation schemes. With the implementation of the research programme to evaluate irrigation performance of the RPIP-Brazil project, one of the selected pilot areas was the Senator Nilo Coelho Irrigation District, Pernambuco. Various indicators, related to irrigated area, water requirements, water supply, energy and water tariff, were quantified and analysed, showing a profile of the irrigation scheme performance. The indicators utilized gave promising results over the years of monitoring and showed an inter-dependent relationship among them.

The use of crumb rubber in asphalt mixtures using the dry process

The modification process of hot mix asphalts in which crumb rubber is initially mixed with the mineral aggregates before the addition of the binder is known as dry process. This process has as main advantages the use of conventional mixing plants and, at least in principle, has no limitation of the incorporated rubber content. The aim of this paper is to study the influence of the incorporated crumb rubber content in the mechanical behavior of dense graded mixes ( grade envelope C of Brazilian specification DNER-ES 313/97). For this purpose, laboratory tests were carried out to determine the main properties to be used in numerical analyses of a structure of flexible pavement executed with that type of asphalt mixture. The mechanical properties of asphalt hot mixes used in the numerical analysis were determined by laboratory tests (stiffness modulus and fatigue life). The studied asphalt hot mixes were produced with a crumb rubber obtained by the milling process at ambient temperature and a straight binder AC 50/70 (classification by penetration). The incorporated rubber content varied from 2% up to 3,6% in relation to the mineral aggregate mixture. For the sake of comparison, a conventional asphalt mixture produced with straight binder AC 50/70 and an asphalt-rubber hot mix produced by wet process were also studied. The results showed that the asphalt hot mixes modified with crumb rubber by dry process presented a significant improvement in terms of mechanical behavior in relation to conventional asphalt hot mixes, especially in terms of increase of fatigue life, as can be observed in the numerical analysis performed.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ).Cepsa.Biosafe.Bezerras Ltda

OPTIMIZATION OF ASPHALT RUBBER HOT MIXES BASED ON PERFORMANCE LABORATORY TESTS

ABSTRACT: Asphalt binders modified with crumb rubber recycled from ground tires have been successfully used in asphalt mixtures improving the mechanical and functional behaviour of the pavements. This paper shows the influence of several factors that affect the behaviour of asphalt-rubber (AR) and of hot mixes made with this material. Modified binders were prepared using a straight binder with 35/50 penetration and rubber obtained by the environmental process. Samples of asphalt-rubber were collected at different digestion time and temperature and conventional characterization tests were performed. Gap-graded hot mixes were prepared using 8% of modified AR binder and resilient modulus and fatigue tests were carried out. Tests with the modified binder showed a great influence of the rubber content, digestion time and temperature in the asphalt-rubber behaviour. The results of mechanical tests revealed that an increase of rubber content enhances fatigue life and decreases the resilient modulus of the asphalt mixes studied

The Kormendy relation of cluster galaxies in PPS regions

We study a sample of 936 early-type galaxies located in 48 low-z regular galaxy clusters with $M_{200}\geq 10^{14}~ M_\odot$ at $z< 0.1$. We examine variations in the Kormendy relation (KR) according to their location in the projected phase space (PPS) of the clusters. We have used a combination of Bayesian statistical methods to identify possible differences between the fitted relations. Our results indicate that the overall KR is better fitted when we take into account the information about PPS regions. We also find that objects with time since infall $\geq 6.5$ Gyr have a significant statistical difference of the KR coefficients relative to objects that are more recent in the cluster environment. We show that giant central ellipticals are responsible for tilting the KR relation towards smaller slopes. These galaxies present a late growth probably due to cumulative preprocessing during infall, plus cannibalism and accretion of smaller stripped objects near the center of the clusters.Comment: 8 pages, 8 figures, appendix, published in MNRAS. arXiv admin note: text overlap with arXiv:2302.0428

Urinary Monocyte Chemoattractant Protein-1 Levels and Interstitial Changes in the Renal Cortex and Their Relationship with Loss of Renal Function in Renal Transplant Patients with Delayed Graft Function

Background: Inflammatory cell infiltration and residual areas of fibrosis in kidneys after renal transplantation can lead to functional abnormalities with long-term implications. Objectives: The aim of this study was to determine urinary monocyte chemoattractant protein-1 (uMCP-1) levels, relative cortical interstitial area (RCIA), and cortical tubulointerstitial macrophage infiltration in renal transplant patients with delayed graft function (DGF) and their possible correlation with graft outcome. Design: Patients were followed after biopsies for one year, and their renal function and structure were evaluated, as well as parameters of inflammatory process. Setting: Clinical Hospital of the School of Medicine of Ribeirão Preto. Patients: Twenty-two cadaveric kidney transplant recipients with DGF were followed for one year. Measurements: Renal function, RCIA, macrophages infiltration and uMCP-1 levels were evaluated. Methods: Renal function was evaluated by plasma creatinine levels. RCIA was determined by morphometry. Immunohistochemical staining of macrophages was performed using an anti-CD68 monoclonal antibody. uMCP-1 levels were determined using a human MCP-1/CCL2 immunoassay kit. Results: There was a significant increase in uMCP-1 levels in transplant patients compared with controls ( p < 0.001). RCIA was 7.1% (6.4 to 9.2; median and 25th to 75th percentiles) in controls and 37.1% (28.1 to 43.7) in patients with kidney transplants ( p < 0.001). The patients who presented with a higher RCIA in the first biopsy showed higher levels of plasma creatinine one year after transplantation (r = 0.44; p < 0.05). The number of tubulointerstitial macrophages per 0.10 mm 2 grid field was higher in the renal cortex of transplant patients compared with the controls (19.4 (9.0 to 47.1) vs. 2.5 (1.8 to 3.4), p < 0.001). There was also a positive correlation between the RCIA and the number of tubulointerstitial macrophages in the renal cortex of these patients (r = 0.49; p < 0.001). Limitations: The number of patients studied was relatively small and may not be reflecting outcomes over a larger spectrum of kidney cadaveric transplants. Conclusions: Our results demonstrate increased levels of uMCP-1 in transplant patients with DGF, in addition to increased tubulointerstitial macrophage infiltration and RCIA, which could predict the outcome of renal function in these patients

Anomalous Nernst Effect in flexible co-based amorphous ribbons

Fe3Co67Cr3Si15B12 ribbons with a high degree of flexibility and excellent corrosion stability were produced by rapid quenching technique. Their structural, magnetic, and thermomagnetic (Anomalous Nernst Effect) properties were studied both in an as-quenched (NR) state and after stress annealing during 1 h at the temperature of 350 °C and a specific load of 230 MPa (AR). X-ray diffraction was used to verify the structural characteristics of our ribbons. Static magnetic properties were explored by inductive technique and vibrating sample magnetometry. The thermomagnetic curves investigated through the Anomalous Nernst Effect are consistent with the obtained magnetization results, presenting a linear response in the thermomagnetic signal, an interesting feature for sensor applications. Additionally, Anomalous Nernst Effect coefficient SANE values of 2.66μV/K and 1.93μV/K were estimated for the as-quenched and annealed ribbons, respectively. The interplay of the low magnetostrictive properties, soft magnetic behavior, linearity of the thermomagnetic response, and flexibility of these ribbons place them as promising systems to probe curved surfaces and propose multifunctional devices, including magnetic field-specialized sensors.M.A.C. thanks CAPES (8887.573100/2020-00) and CNPq. A.F. thanks the FCT (CTTI-31/18- C.F. (2) junior researcher contract). G.V.K was supported in the frame of the Priority-2030 Program of Ural Federal University

Nitrogênio e promotor de crescimento: efeitos no crescimento e desenvolvimento do algodão colorido verde.

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