Use of plastic waste (poly-ethylene terephthalate) in asphalt concrete mixture as aggregate replacement.

Science.gov (United States)

Hassani, Abolfazl; Ganjidoust, Hossein; Maghanaki, Amir Abedin

2005-08-01

One of the environmental issues in most regions of Iran is the large number of bottles made from poly-ethylene terephthalate (PET) deposited in domestic wastes and landfills. Due to the high volume of these bottles, more than 1 million m3 landfill space is needed for disposal every year. The purpose of this experimental study was to investigate the possibility of using PET waste in asphalt concrete mixes as aggregate replacement (Plastiphalt) to reduce the environmental effects of PET disposal. For this purpose the mechanical properties of plastiphalt mixes were compared with control samples. This study focused on the parameters of Marshall stability, flow, Marshall quotient (stability-to-flow ratio) and density. The waste PET used in this study was in the form of granules of about 3 mm diameter which would replace (by volume) a portion of the mineral coarse aggregates of an equal size (2.36-4.75 mm). In all prepared mixes the determined 6.6% optimum bitumen content was used. In this investigation, five different percentages of coarse aggregate replacement were used. The results showed that the aggregate replacement of 20% by volume with PET granules would result in a reduction of 2.8% in bulk compacted mix density. The value of flow in the plastiphalt mix was lower than that of the control samples. The results also showed that when PET was used as partial aggregate replacement, the corresponding Marshall stability and Marshall quotient were almost the same as for the control samples. According to most of specification requirement, these results introduce an asphalt mix that has properties that makes it suitable for practical use and furthermore, the recycling of PET for asphalt concrete roads helps alleviate an environmental problem and saves energy.

Experimental Investigation on Damping Property of Coarse Aggregate Replaced Rubber Concrete

Science.gov (United States)

Sugapriya, P.; Ramkrishnan, R.; Keerthana, G.; Saravanamurugan, S.

2018-02-01

Rubber has good damping and vibrational characteristics and can reduce cracking significantly due to its elastic nature. This property of rubber can be incorporated in concrete to control vibrations and create better pavements. Crumb Rubber on being dumped in landfills has serious repercussions and causes soil and land pollution. An innovative use of waste tires is shredding them into small pieces and using them as a replacement for coarse aggregate. Crumb rubber is obtained by chopping scrap tires, and in this study it was added in two different sets named SET 1 - Treated Crumb Rubber and concrete, and SET 2 - Treated Crumb rubber with Ultra Fine GGBS as admixture in concrete. Coarse aggregate replaces Rubber in each of the 2 SET’s in proportions of 5, 10, 15 and 20%. Properties like Compressive Strength, Young’s Modulus, Direct and Semi direct Ultrasonic Pulse Velocity, Sorptivity, Damping ratio and Frequency were found out. Deformation and mode shape were studied with modal analysis and static analysis by applying a uniform pressure corresponding to the highest compressive strength of the slab, using ANSYS.

Processed bottom ash for replacing fine aggregate in making high-volume fly ash concrete

Directory of Open Access Journals (Sweden)

Antoni

2017-01-01

Full Text Available Bottom ash is a coal plant by-product that is abundant and underutilized. There is the potential use of bottom ash as a fine aggregate replacement in concrete mixtures; however, the problems of water absorption and uniformity of quality of the material need to be overcome first. In this study, bottom ash was treated by sieve separation and pounding to smaller particle size for use as a sand substitute. The physical and chemical characteristics of bottom ash were tested after treatment including water absorption, sieve analysis, and fineness modulus. Highvolume fly ash (HVFA mortar specimens were made and the compressive strength and flowability test using bottom ash after treatment are compared with that of the sand specimen. Low water to cementitious ratio was used to ensure higher strength from the cementitious paste and superplasticizer demand was determined for each treatment. The result showed that bottom ash can be used as fine aggregate replacement material. Sieve separation of the bottom ash could produce 75% of the compressive strength compared with the control sand specimen, whereas pounded bottom ash could have up to 96% of the compressive strength of the control specimen. A 28-day compressive strength of 45 MPa was achievable with 100% replacement of fine aggregate with bottom ash.

The Utilisation of Shredded PET as Aggregate Replacement for Interlocking Concrete Block

Science.gov (United States)

Mokhtar, M.; Kaamin, M.; Sahat, S.; Hamid, N. B.

2018-03-01

The consumption of plastic has grown substantially all over the world in recent years and this has created huge quantities of plastic-based waste. Plastic waste is now a serious environmental threat to the modern way of living, although steps were taken to reduce its consumption. This creates substantial garbage every day, which is much unhealthy. Plastic bottles such as Polyethylene terephthalate (PET) was use as the partially component in this making of interlocking blocks concrete. This project investigates the strength and workability of the interlocking block concrete by replacing course aggregate with % PET. The suitability of recycled plastics (PET) as course aggregate in interlocking block concrete and its advantages are discussed here. Moreover, there were more benefits when using interlocking block than using conventional block such as it easy for construction because they are aligning, easy to place, high speed stacking and they offer more resistance to shear and buildings would be even stronger. Based on the test perform, the failure parameter were discussed .From the compressive strength test result, it shows that the strength of concrete block decreased with increased of PET used. From the results, it shows that higher compressive strength was found with 5% natural course aggregate replaced with PET compared to other percentages.

Early age shrinkage pattern of concrete on replacement of fine aggregate with industrial by-product

Directory of Open Access Journals (Sweden)

R.K. Mishra

2016-10-01

Full Text Available This is an experimental work carried out to investigate early age shrinkage pattern of concrete, prepared, on 50% replacement of industrial by-product (like pond ash and granulated blast furnace slag as fine aggregate using OPC, PPC and PSC as a binder. This is to observe the effect of pond ash and slag as they are having some cementitious properties and effect of cement type is also discussed. All the mixes were prepared keeping in view of pumpable concrete without any super plasticizers. Higher shrinkage value indicates the presence of more bleed water or internal moisture. It is concluded that slag is the best option for fine aggregate replacement for concrete making and durable structure.

Fresh and mechanical properties of self-compacting concrete with coarse aggregate replacement using Waste of Oil Palm Shell

Science.gov (United States)

Prayuda, Hakas; Saleh, Fadillawaty; Ilham Maulana, Taufiq; Monika, Fanny

2018-05-01

Self-compacting Concrete (SCC) is a real innovation that can solidify itself without the help of tools to ease field practice. In its implementation, SCC can use alternative materials to reduce waste, such as Oil Palm Shell (OPS). In this research, OPS used as a replacement of crushed stone as the main coarse aggregate. The concrete mixture used consists of cement, sand, crushed stone, OPS as a variation of aggregate substitutes, palm oil fuel ash, and superplasticizer. OPS used were variated with 0%, 5%, 10%, 25% and 50% of crushed stone aggregate weight with age up to 28 days. Tests were conducted on fresh and mechanical properties. From the results, it is known that replacement of aggregate using OPS meets fresh properties criteria and although the compressive strength of OPS concrete mixture is lower than normal SCC, OPS still can be an alternative in making SCC and reducing palm oil industrial waste.

Utilization of fly ash as partial sand replacement in oil palm shell lightweight aggregate concrete

Science.gov (United States)

Nazrin Akmal, A. Z. Muhammad; Muthusamy, K.; Mat Yahaya, F.; Hanafi, H. Mohd; Nur Azzimah, Z.

2017-11-01

Realization on the increasing demand for river sand supply in construction sector has inspired the current research to find alternative material to reduce the use of natural sand in oil palm shell lightweight aggregate concrete (OPS LWAC) production. The existence of fly ash, a by-product generated from coal power plant, which pose negative impact to the environment when it is disposed as waste, were used in this research. The effect of fly ash content as partial sand replacement towards workability and compressive strength of OPS lightweight aggregate concrete were investigated. Four concrete mixes containing various percentage of fly ash that are 0%, 10%, 20% and 30% by weight of sand were used in the experimental work. All mixes were cast in form of cubes before subjected to water curing until the testing age. Compressive strength test were conducted at 1, 3, 7 and 28 days. The finding shows that the workability of the OPS LWAC decreases when more fly ash are used as sand replacement. It was found that adding of 10% fly ash as sand replacement content resulted in better compressive strength of OPS LWAC, which is higher than the control mix.

Experimental investigation on the properties of concrete containing post-consumer plastic waste as coarse aggregate replacement

Directory of Open Access Journals (Sweden)

Zasiah TAFHEEM

2018-03-01

Full Text Available The consumption of various forms of plastic has been increased in recent days due to the boost in industrialization and other human activities. Most of the plastic wastes are abandoned and require large landfill area for storage. More importantly, the low biodegradability of plastic poses a serious threat to environment protection issue. Various methods have been followed for the disposal of plastic in an attempt to reduce the negative impact of the plastic on the environment. Recently, various types of plastic have been incorporated in concrete to minimize the exposure of plastic to the environment. The aim of this study is to investigate the properties of concrete containing polyethylene terephthalate (PET, and high density polyethylene (HDPE plastic that were used as partial replacement of coarse aggregate (CA. In this study, four compositions of stone aggregate(S: plastic waste ratios have been used by volume basis: 100% S: 0% Plastic (control concrete, 90% S: 10% PET, 90% S: 10% HDPE, and 90% S: 5% PET+5% HDPE. The effects of waste plastic addition on the mechanical properties of concrete are presented in this paper. Test results reveal that minimum reduction in compressive strength has been found 35% in case of 10% PET plastic replaced concrete whereas splitting tensile strength for 10% PET replaced concrete has been increased by 21% while compared to control concrete. In addition, fresh unit weight of concrete containing plastic waste has been decreased by 4% in comparison to control concrete.

Study of Compressive Strength of Concrete with Coal Power Plant Fly Ash as Partial Replacement of Cement and Fine Aggregate

Directory of Open Access Journals (Sweden)

FAREED AHMED MEMON

2010-10-01

Full Text Available This research study comprises of concrete cubes made with Ordinary Portland Cement and with different configurations of fly ash by replacing cement and fine aggregate. To achieve the aim of this study, total 81 concrete cubes were cast. Among 81 cubes, 9 cubes were made with normal concrete, 36 cubes were made by replacing 25%, 50%, 75% and 100% of fine aggregate with fly ash and 36 cubes were made by replacing 10%, 25%, 50%, and 75% of cement with fly ash. The cubes were 6\\" x 6\\" in cross-section, and the mix design was aimed for 5000 psi. After proper curing of all 81 cubes, they were tested at 3, 7 and 28 days curing age. The cubes were tested in Forney Universal Testing Machine. By analyzing the test results of all the concrete cubes, the following main findings have been drawn. The compressive strength of concrete cubes made by replacing 100 % fine aggregate by fly ash was higher than the concrete cubes made with Ordinary Portland Cement at all 3, 7 and 28 days curing ages. On the other hand, the compressive strength of concrete cubes made by replacing 10 % and 25 % cement by fly ash was slightly lower than the concrete cubes made with Ordinary Portland Cement at all curing ages, whereas, the compressive strength of concrete cubes made by replacing 50 % and 75 % of cement by fly ash were quite lower than the concrete cubes made with Ordinary Portland Cement at all curing ages.

Properties of concrete containing different type of waste materials as aggregate replacement exposed to elevated temperature – A review

Science.gov (United States)

Ghadzali, N. S.; Ibrahim, M. H. W.; Sani, M. S. H. Mohd; Jamaludin, N.; Desa, M. S. M.; Misri, Z.

2018-04-01

Concrete is the chief material of construction and it is non-combustible in nature. However, the exposure to the high temperature such as fire can lead to change in the concrete properties. Due to the higher temperature, several changes in terms of mechanical properties were observed in concrete such as compressive strength, modulus of elasticity, tensile strength and durability of concrete will decrease significantly at high temperature. The exceptional fire-proof achievement of concrete is might be due to the constituent materials of concrete such as its aggregates. The extensive use of aggregate in concrete will leads to depletion of natural resources. Hence, the use of waste and other recycled and by-product material as aggregates replacements becomes a leading research. This review has been made on the utilization of waste materials in concrete and critically evaluates its effects on the concrete performances during the fire exposure. Therefore, the objective of this paper is to review the previous search work regarding the concrete containing waste material as aggregates replacement when exposed to elevated temperature and come up with different design recommendations to improve the fire resistance of structures.

An overview of aggregate resources in the United States

Science.gov (United States)

Langer, William H.; Scott, P.W.; Bristow, C.M.

2002-01-01

In 2000 the USA produced about 2.7 billion tonnes of aggregate worth about $13.7 billion. Both crushed stone and sand and gravel are produced in virtually every State, although limited quantities are available in the Gulf Coastal Plain, the Colorado Plateau , the Wyoming Basin and the Great Plains. Prices vary depending on the product and location. Most aggregates are transported by road, and minor amounts by railroad, barge on navigable inland channels, and through the Great Lake ports. Imports and exports of aggregates are very minor. A major amount f crushed stone aggregates is consumed by concrete aggregate. Recycled aggregates account for about 8% of total demand, although the amount recycled is thought to be increasing. Current issues facing the inductry unclude the differences in quality specifications between States, adjusting to the increasing concern for the impact of aggregate mining on the environmentm, health issues from particulate matter and crystalline silica, and the complexity of obtaining permits for extraction. Redcustion in the number od companies extracting aggregrates is likely to occur through acquisitions.

Processed bottom ash for replacing fine aggregate in making high-volume fly ash concrete

OpenAIRE

Antoni; Sulistio Aldi Vincent; Wahjudi Samuel; Hardjito Djwantoro; Hardjito Djwantoro

2017-01-01

Bottom ash is a coal plant by-product that is abundant and underutilized. There is the potential use of bottom ash as a fine aggregate replacement in concrete mixtures; however, the problems of water absorption and uniformity of quality of the material need to be overcome first. In this study, bottom ash was treated by sieve separation and pounding to smaller particle size for use as a sand substitute. The physical and chemical characteristics of bottom ash were tested after treatment includi...

Comparative Study on Carbonated and Non-Carbonated Recycled Aggregate Concrete with Glass Powder as Partial Replacement for OPC

Directory of Open Access Journals (Sweden)

Abhishek Patil

2017-12-01

Full Text Available Recycled aggregates (RA possess the ability to be recycled, if undesirable properties are counteracted viz, porous mortar attached to it, with high water absorption and low density, this technique, accelerated carbonation can be one such to technique to counteract undesirable properties of RA, replacement of 20% of cement by glass powder assists in reducing w/c ratio[1][6] when used in concrete[2] suppress ASR reaction[1], this paper explains a new possibility of recycling concrete, work done and findings for improvising Recycled aggregate concrete (RAC and exploring the feasibility for use of RA in the near future.

Solid-State Thyratron Replacement. Final Report

Energy Technology Data Exchange (ETDEWEB)

Roth, Ian [Diversified Technologies, Inc., Bedford, MA

2017-12-12

Under this SBIR, DTI developed a solid-state switch as an alternative to legacy thyratron equipment. Our Phase II objective was to make a solid-state thyratron replacement that would provide equivalent or better performance, much higher reliability (at least a 20 year lifetime, compared to a thyratron’s two-year lifetime) and would sell for ~3x the cost of a thyratron, or less than $40k. We were successful in building a solid-state switch which could reliably function as a thyratron replacement. The unit was designed to directly replace the thyratrons currently being used at SLAC’s Linac Coherent Light Source (LCLS), and was built in a tank that was small enough to fit into the existing thyratron cabinet, providing a true form-fit-function replacement path. We tested the switch at the full operating specifications: 48 kV, 6.3 kA, and 1 µs risetime. We also demonstrated a peak-to-peak pulse jitter of 1.5 ns, which is five times shorter than is typical for thyratrons. This lower jitter would improve the performance of the LCLS beam. The predicted reliability is more than 80 years, which is 40 times greater than a thyratron.

Mechanical properties of recycled concrete with demolished waste concrete aggregate and clay brick aggregate

Science.gov (United States)

Zheng, Chaocan; Lou, Cong; Du, Geng; Li, Xiaozhen; Liu, Zhiwu; Li, Liqin

2018-06-01

This paper presents an experimental investigation on the effect of the replacement of natural coarse aggregate (NCA) with either recycled concrete aggregate (RCA) or recycled clay brick aggregate (RBA) on the compressive strengths of the hardened concrete. Two grades (C25 and C50) of concrete were investigated, which were achieved by using different water-to-cement ratios. In each grade concrete five different replacement rates, 0%, 25%, 50%, 75% and 100% were considered. In order to improve the performance of the recycled aggregates in the concrete mixes, the RCA and RBA were carefully sieved by using the optimal degradation. In this way the largest reduction in the 28-day compressive strength was found to be only 7.2% and 9.6% for C25 and C50 recycled concrete when the NCA was replaced 100% by RCA, and 11% and 13% for C25 and C50 recycled concrete when the NCA was replaced 100% by RBA. In general, the concrete with RCA has better performance than the concrete with RBA. The comparison of the present experimental results with those reported in literature for hardened concrete with either RCA or RBA demonstrates the effectiveness in improving the compressive strength by using the optimal gradation of recycled aggregates.

Sustainable normal and high strength recycled aggregate concretes using crushed tested cylinders as coarse aggregates

Directory of Open Access Journals (Sweden)

Bilal S. Hamad

2017-12-01

Full Text Available The paper reports on a research program that was designed at the American University of Beirut (AUB to investigate the fresh and hardened mechanical properties of a high performance concrete mix produced with partial or full substitution of crushed natural lime-stone aggregates with recycled aggregates from crushed tested cylinders in batching plants. Choosing crushed cylinders as source of recycling would result in reusing portion of the waste products of the concrete production industry. An extensive concrete batching and testing program was conducted to achieve two optimum normal and high strength concrete mixes. The variables were the nominal concrete strength (28 or 60 MPa and the percentage replacement of natural coarse aggregates with recycled aggregates from crushed tested cylinders (0, 20, 40, 60, 80, or 100%. Normal strength tested cylinders were used as source of the recycled aggregates for the normal strength concrete (NSC mix and high strength tested cylinders were used for the high strength concrete (HSC mix. Tests on the trial batches included plastic state slump and hardened state mechanical properties including cylinder compressive strength, cylinder splitting tensile strength, modulus of elasticity, and standard beams flexural strength. The results indicated no significant effect on the slump and around 10% average reduction in the hardened mechanical properties for both investigated levels of concrete compressive strength.

The mechanical properties of brick containing recycled concrete aggregate and polyethylene terephthalate waste as sand replacement

Science.gov (United States)

Sheikh Khalid, Faisal; Bazilah Azmi, Nurul; Natasya Mazenan, Puteri; Shahidan, Shahiron; Ali, Noorwirdawati

2018-03-01

This research focuses on the performance of composite sand cement brick containing recycle concrete aggregate and waste polyethylene terephthalate. This study aims to determine the mechanical properties such as compressive strength and water absorption of composite brick containing recycled concrete aggregate (RCA) and polyethylene terephthalate (PET) waste. The bricks specimens were prepared by using 100% natural sand, they were then replaced by RCA at 25%, 50% and 75% with proportions of PET consists of 0.5%, 1.0% and 1.5% by weight of natural sand. Based on the results of compressive strength, only RCA 25% with 0.5% PET achieve lower strength than normal bricks while others showed a high strength. However, all design mix reaches strength more than 7N/mm2 as expected. Besides that, the most favorable mix design that achieves high compressive strength is 75% of RCA with 0.5% PET.

performance of concrete with partial replacement of fine aggregates

African Journals Online (AJOL)

user

aggregate with waste glass that will result in optimal compressive strength. A total of 36 cubes were ... to achieve the required strength and durability. The fine aggregate is ..... Ceramic Foundation Annual Technical Report, pp. 143-147. 2000.

Lymphoid Aggregates That Resemble Tertiary Lymphoid Organs Define a Specific Pathological Subset in Metal-on-Metal Hip Replacements

Science.gov (United States)

Barone, Francesca; Hardie, Debbie L.; Matharu, Gulraj S.; Davenport, Alison J.; Martin, Richard A.; Grant, Melissa; Mosselmans, Frederick; Pynsent, Paul; Sumathi, Vaiyapuri P.; Addison, Owen; Revell, Peter A.; Buckley, Christopher D.

2013-01-01

Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) has been used to describe the histological lesion associated with metal-on-metal (M-M) bearings. We tested the hypothesis that the lymphoid aggregates, associated with ALVAL lesions resemble tertiary lymphoid organs (TLOs). Histopathological changes were examined in the periprosthetic tissue of 62 M-M hip replacements requiring revision surgery, with particular emphasis on the characteristics and pattern of the lymphocytic infiltrate. Immunofluorescence and immunohistochemistry were used to study the classical features of TLOs in cases where large organized lymphoid follicles were present. Synchrotron X-ray fluorescence (XRF) measurements were undertaken to detect localisation of implant derived ions/particles within the samples. Based on type of lymphocytic infiltrates, three different categories were recognised; diffuse aggregates (51%), T cell aggregates (20%), and organised lymphoid aggregates (29%). Further investigation of tissues with organised lymphoid aggregates showed that these tissues recapitulate many of the features of TLOs with T cells and B cells organised into discrete areas, the presence of follicular dendritic cells, acquisition of high endothelial venule like phenotype by blood vessels, expression of lymphoid chemokines and the presence of plasma cells. Co-localisation of implant-derived metals with lymphoid aggregates was observed. These findings suggest that in addition to the well described general foreign body reaction mediated by macrophages and a T cell mediated type IV hypersensitivity response, an under-recognized immunological reaction to metal wear debris involving B cells and the formation of tertiary lymphoid organs occurs in a distinct subset of patients with M-M implants. PMID:23723985

Effect of shear rate on aggregate size and structure in the process of aggregation and at steady state

Czech Academy of Sciences Publication Activity Database

Bubáková, Petra; Pivokonský, Martin; Filip, Petr

2013-01-01

Roč. 235, February (2013), s. 540-549 ISSN 0032-5910 R&D Projects: GA ČR GAP105/11/0247 Institutional support: RVO:67985874 Keywords : aggregation * aggregate size * fractal dimension * shear rate * steady state * time evolution Subject RIV: BK - Fluid Dynamics Impact factor: 2.269, year: 2013

Microstructural characterization of concrete prepared with recycled aggregates.

Science.gov (United States)

Guedes, Mafalda; Evangelista, Luís; de Brito, Jorge; Ferro, Alberto C

2013-10-01

Several authors have reported the workability, mechanical properties, and durability of concrete produced with construction waste replacing the natural aggregate. However, a systematic microstructural characterization of recycled aggregate concrete has not been reported. This work studies the use of fine recycled aggregate to replace fine natural aggregate in the production of concrete and reports the resulting microstructures. The used raw materials were natural aggregate, recycled aggregate obtained from a standard concrete, and Portland cement. The substitution extent was 0, 10, 50, and 100 vol%; hydration was stopped at 9, 24, and 96 h and 28 days. Microscopy was focused on the cement/aggregate interfacial transition zone, enlightening the effect of incorporating recycled aggregate on the formation and morphology of the different concrete hydration products. The results show that concretes with recycled aggregates exhibit typical microstructural features of the transition zone in normal strength concrete. Although overall porosity increases with increasing replacement, the interfacial bond is apparently stronger when recycled aggregates are used. An addition of 10 vol% results in a decrease in porosity at the interface with a corresponding increase of the material hardness. This provides an opportunity for development of increased strength Portland cement concretes using controlled amounts of concrete waste.

Recycled Concrete as Aggregate for Structural Concrete Production

Directory of Open Access Journals (Sweden)

Mirjana Malešev

2010-04-01

Full Text Available A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC as a control concrete and two types of concrete made with natural fine and recycled coarse aggregate (50% and 100% replacement of coarse recycled aggregate. Ninety-nine specimens were made for the testing of the basic properties of hardened concrete. Load testing of reinforced concrete beams made of the investigated concrete types is also presented in the paper. Regardless of the replacement ratio, recycled aggregate concrete (RAC had a satisfactory performance, which did not differ significantly from the performance of control concrete in this experimental research. However, for this to be fulfilled, it is necessary to use quality recycled concrete coarse aggregate and to follow the specific rules for design and production of this new concrete type.

Durability and acoustics of concrete with slag of cupola furnace as fine aggregate replacement

Directory of Open Access Journals (Sweden)

Ricardo Alfredo Cruz Hernández

2015-01-01

Full Text Available In this paper, it was evaluated the performance of concrete with crushed slag of cupola furnace (SCF as sand replacement in percentages of 0 %, 10 %, 15 % and 20 %, subjected to accelerated chemical attacks of carbonation, sulfation and alkali-aggregate reaction (AAR. The sound absorption characteristics of the material were determined through the sound absorption coefficient (α, and the noise reduction coefficient (NRC. Carbonation was evaluated through a closed camera with the 70 % concentration of carbon dioxide and conditions of relative humidity between 50 % and 70 %. The results indicated that the penetration depth of CO2 is lower when greater the percentage of substitution is. To accelerate the attack by sulfates, specimens were immersed in aqueous solution of sodium sulfate anhydrous (Na2SO4 1N with cycles of wetting and drying. It determined that the impairment presented in concrete paste is directly proportional to the percentage of sand replacement. The acceleration of the AAR in the concrete was carried out by immersing specimens in an aqueous solution of sodium hydroxide (NaOH for 16 days. The test concluded that the inclusion of SCF is not favorable for AAR. The measurement of sound absorption coefficient was taken by the method of impedance tube, relating minimum and maximum values of stationary wave amplitude. The results showed that SCF with higher sand replacement are favorable for the noise absorption in buildings.

Compressive strength and resistance to chloride ion penetration and carbonation of recycled aggregate concrete with varying amount of fly ash and fine recycled aggregate.

Science.gov (United States)

Sim, Jongsung; Park, Cheolwoo

2011-11-01

Construction and demolition waste has been dramatically increased in the last decade, and social and environmental concerns on the recycling have consequently been increased. Recent technology has greatly improved the recycling process for waste concrete. This study investigates the fundamental characteristics of concrete using recycled concrete aggregate (RCA) for its application to structural concrete members. The specimens used 100% coarse RCA, various replacement levels of natural aggregate with fine RCA, and several levels of fly ash addition. Compressive strength of mortar and concrete which used RCA gradually decreased as the amount of the recycled materials increased. Regardless of curing conditions and fly ash addition, the 28 days strength of the recycled aggregate concrete was greater than the design strength, 40 MPa, with a complete replacement of coarse aggregate and a replacement level of natural fine aggregate by fine RCA up to 60%. The recycled aggregate concrete achieved sufficient resistance to the chloride ion penetration. The measured carbonation depth did not indicate a clear relationship to the fine RCA replacement ratio but the recycled aggregate concrete could also attain adequate carbonation resistance. Based on the results from the experimental investigations, it is believed that the recycled aggregate concrete can be successfully applied to structural concrete members. Copyright © 2011 Elsevier Ltd. All rights reserved.

High performance of treated and washed MSWI bottom ash granulates as natural aggregate replacement within earth-moist concrete.

Science.gov (United States)

Keulen, A; van Zomeren, A; Harpe, P; Aarnink, W; Simons, H A E; Brouwers, H J H

2016-03-01

Municipal solid waste incineration bottom ash was treated with specially designed dry and wet treatment processes, obtaining high quality bottom ash granulate fractions (BGF) suitable for up to 100% replacement of natural gravel in concrete. The wet treatment (using only water for separating and washing) significantly lowers the leaching of e.g. chloride and sulfate, heavy metals (antimony, molybdenum and copper) and dissolved organic carbon (DOC). Two potential bottom ash granulate fractions, both in compliance with the standard EN 12620 (aggregates for concrete), were added into earth-moist concrete mixtures. The fresh and hardened concrete physical performances (e.g. workability, strength and freeze-thaw) of high strength concrete mixtures were maintained or improved compared with the reference mixtures, even after replacing up to 100% of the initial natural gravel. Final element leaching of monolithic and crushed granular state BGF containing concretes, showed no differences with the gravel references. Leaching of all mixtures did not exceed the limit values set by the Dutch Soil Quality Degree. In addition, multiple-life-phase emission (pH static test) for the critical elements of input bottom ash, bottom ash granulate (BGF) and crushed BGF containing concrete were assessed. Simulation pH lowering or potential carbonation processes indicated that metal (antimony, barium, chrome and copper) and sulfate element leaching behavior are mainly pH dominated and controlled, although differ in mechanism and related mineral abundance. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of recycled aggregate quality and proportioning criteria on recycled concrete properties.

Science.gov (United States)

López-Gayarre, F; Serna, P; Domingo-Cabo, A; Serrano-López, M A; López-Colina, C

2009-12-01

This paper presents the results of experimental research using concrete produced by substituting part of the natural coarse aggregates with recycled aggregates from concrete demolition. The influence of the quality of the recycled aggregate (amount of declassified and source of aggregate), the percentage of replacement on the targeted quality of the concrete to be produced (strength and workability) has been evaluated. The granular structure of concrete and replacement criteria were analyzed in this study, factors which have not been analyzed in other studies. The following properties of recycled concretes were analyzed: density, absorption, compressive strength, elastic modulus, amount of occluded air, penetration of water under pressure and splitting tensile strength. A simplified test program was designed to control the costs of the testing while still producing sufficient data to develop reliable conclusions in order to make the number of tests viable whilst guaranteeing the reliability of the conclusions. Several factors were analyzed including the type of aggregate, the percentage of replacement, the type of sieve curve, the declassified content, the strength of concrete and workability of concrete and the replacement criteria. The type of aggregate and the percentage of replacement were the only factors that showed a clear influence on most of the properties. Compressive strength is clearly affected by the quality of recycled aggregates. If the water-cement ratio is kept constant and the loss of workability due to the effect of using recycled aggregate is compensated for with additives, the percentage of replacement of the recycled aggregate will not affect the compressive strength. The elastic modulus is affected by the percentage of replacement. If the percentage of replacement does not exceed 50%, the elastic modulus will only change slightly.

THE AGGREGATE IMPLICATIONS OF MACHINE REPLACEMENT: THEORY AND EVIDENCE

OpenAIRE

John Haltiwanger; Russell Cooper

1992-01-01

The authors study an economy in which producers incur resource costs to replace depreciated machines. The process of costly replacement and depreciation creates endogenous fluctuations in productivity, employment, and output of a single producer. The authors explore the spillover effects of machine replacement on other sectors of the economy and provide conditions for synchronized machine replacement by multiple independent producers. The implications of their model are generally consistent w...

Sociocultural dimensions of supply and demand for natural aggregate; examples from the Mid-Atlantic region, United States

Science.gov (United States)

Robinson, Gilpin R.; Brown, William M.

2002-01-01

The United States uses large quantities of natural aggregate to build and maintain a continuously expanding infrastructure. In recent years, per capita demand for aggregate in the United States has grown to about 9.7 metric tons (10.7 tons) per person per year. Over the next 25 years, the aggregate industry expects to mine quantities equivalent to all aggregate mined in the United States over the past 100 years. The issues surrounding supply and demand for aggregate in the mid-Atlantic states of Maryland, Pennsylvania, Virginia, and West Virginia illustrate competing requirements for industrial minerals and many simultaneous social and environmental objectives.

AN EXPERIMENTAL STUDY ON STRENGTH PARAMETRES OF CONCRETE WITH REPLACMENT OF FINE AGGREGATE BY ROBO SAND

OpenAIRE

T.Dilip Kumar *1 & G.Kalyan 2

2018-01-01

Concrete is the most widely used composite construction material. Fine aggregate plays a very important role for imparting better properties to concrete in its fresh and hardened state. Generally, river sand was used as fine aggregate for construction. Due to the continuous mining of sand from riverbed led to the depletion of river sand and it became a scarce material. Also, samining from river bed caused a lot of environmental issues. As a substitute to river sand, Robo sand has been used. I...

The transformation of waste Bakelite to replace natural fine aggregate in cement mortar

Directory of Open Access Journals (Sweden)

Nopagon Usahanunth

2017-06-01

Full Text Available Bakelite material has been used to produce the various components for cars and consumer goods industry in Thailand. The growth of Bakelite consumption increases Bakelite waste. Bakelite waste is prohibited from disposing of direct landfilling and open burning because of the improper disposal and emission reasons. A large amount of this waste needs the large safe space of warehouse area for keeping which becomes a waste management problem. Size reduction by milling machine is helpful for waste handling and storing, however, the post-milling waste Bakelite plastic utilization shall be studied to maintain the waste storing capacity. There are some studies of the milling machine used for waste plastic size reduction. However, the particular study of milling machine application for waste size reduction and its milling waste utilization is still insufficient in Thailand. The purpose of this research is the use of waste Bakelite aggregate milling machine for Bakelite waste size reduction and use of the post-milling waste Bakelite as a fine aggregate to replace natural sand material in cement mortar. The waste Bakelite fine aggregate (WBFA was mixed in cement mortar mixture with the proportion 0% 20% 40% 60% 80% and 100% by volume for cement mortar sample preparation. The mortar sample was tested for compressive strength follow ASTM standard. The compressive test result of mortar samples will be compared between conventional mortar (0% WBFA and waste Bakelite mortar (WBM as well as comparing with the mortar standard. From an analysis of the sample test data found that the WBFA content in cement mortar mixture can predict the strength of WBM. The compressive strength of WBM at 28 days age with the fraction of WBFA is not exceeded 11.03%, and 23.08% respectively can be met the mortar standard according to the equation. The utilization of WBM to develop mortar non-structural mortar product can be usable from a technical point of view.

Study on Mechanical Properties of Concrete Using Plastic Waste as an Aggregate

Science.gov (United States)

Jaivignesh, B.; Sofi, A.

2017-07-01

Disposal of large quantity of plastic causes land, water and air pollution etc.., so a study is conducted to recycle the plastic in concrete. This work investigates about the replacement of natural aggregate with non-biodegradable plastic aggregate made up of mixed plastic waste in concrete. Several tests are conducted such as compressive strength of cube, split tensile strength of cylinder, flexural strength test of prism to identify the properties and behavior of concrete using plastic aggregate. Replacement of fine aggregate weight by 10%, 15%, 20% with Plastic fine (PF) aggregate and for each replacement of fine aggregate 15%, 20%, 25% of coarse aggregate replacement also conducted with Plastic Coarse(PC) aggregate. In literatures reported that the addition of plastic aggregate in concrete causes the reduction of strength in concrete due to poor bonding between concrete and plastic aggregate, so addition of 0.3% of steel fiber by weight of cement in concrete is done to improve the concrete strength. Totally 60 cubes, 60 cylinders and 40 prisms are casted to identify the compressive strength, split tensile strength and flexural strength respectively. Casted specimens are tested at 7 and 28 days. The identified results from concrete using plastic aggregate are compared with conventional concrete. Result shows that reduction in mechanical properties of plastic aggregate added concrete. This reduction in strength is mainly due to poor bond strength between cement and plastic aggregate.

Recycling of waste glass as a partial replacement for fine aggregate in concrete.

Science.gov (United States)

Ismail, Zainab Z; Al-Hashmi, Enas A

2009-02-01

Waste glass creates serious environmental problems, mainly due to the inconsistency of waste glass streams. With increasing environmental pressure to reduce solid waste and to recycle as much as possible, the concrete industry has adopted a number of methods to achieve this goal. The properties of concretes containing waste glass as fine aggregate were investigated in this study. The strength properties and ASR expansion were analyzed in terms of waste glass content. An overall quantity of 80 kg of crushed waste glass was used as a partial replacement for sand at 10%, 15%, and 20% with 900 kg of concrete mixes. The results proved 80% pozzolanic strength activity given by waste glass after 28 days. The flexural strength and compressive strength of specimens with 20% waste glass content were 10.99% and 4.23%, respectively, higher than those of the control specimen at 28 days. The mortar bar tests demonstrated that the finely crushed waste glass helped reduce expansion by 66% as compared with the control mix.

an investigation into the use of groundnut shell as fine aggregate

African Journals Online (AJOL)

2013-03-01

Mar 1, 2013 ... Groundnut Shell Use as Fine Aggregate Replacement. 55. (a) Plate A. (b) Plate B ... as a waste from a household which uses groundnut for oil making. ..... Analysis of Cement and Aggregate Replacement Ma- terials. Nigerian ...

Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

Directory of Open Access Journals (Sweden)

Hisham Qasrawi

2013-01-01

Full Text Available The effect of using recycled concrete aggregates (RCA on the basic properties of normal concrete is studied. First, recycled aggregate properties have been determined and compared to those of normal aggregates. Except for absorption, there was not a significant difference between the two. Later, recycled aggregates were introduced in concrete mixes. In these mixes, natural coarse aggregate was partly or totally replaced by recycled aggregates. Results show that the use of recycled aggregates has an adverse effect on the workability and air content of fresh concrete. Depending on the water/cement ratio and on the percent of the normal aggregate replaced by RCA, the concrete strength is reduced by 5% to 25%, while the tensile strength is reduced by 4% to 14%. All results are compared with previous research. As new in this research, the paper introduces a simple formula for the prediction of the modulus of elasticity of RCA concrete. Furthermore, the paper shows the variation of the air content of RAC.

Blasted copper slag as fine aggregate in Portland cement concrete.

Science.gov (United States)

Dos Anjos, M A G; Sales, A T C; Andrade, N

2017-07-01

The present work focuses on assessing the viability of applying blasted copper slag, produced during abrasive blasting, as fine aggregate for Portland cement concrete manufacturing, resulting in an alternative and safe disposal method. Leaching assays showed no toxicity for this material. Concrete mixtures were produced, with high aggregate replacement ratios, varying from 0% to 100%. Axial compressive strength, diametrical compressive strength, elastic modulus, physical indexes and durability were evaluated. Assays showed a significant improvement in workability, with the increase in substitution of fine aggregate. With 80% of replacement, the concrete presented lower levels of water absorption capacity. Axial compressive strength and diametrical compressive strength decreased, with the increase of residue replacement content. The greatest reductions of compressive strength were found when the replacement was over 40%. For tensile strength by diametrical compression, the greatest reduction occurred for the concrete with 80% of replacement. After the accelerated aging, results of mechanic properties showed a small reduction of the concrete with blasted copper slag performance, when compared with the reference mixture. Results indicated that the blasted copper slag is a technically viable material for application as fine aggregate for concrete mixtures. Copyright © 2017 Elsevier Ltd. All rights reserved.

Study of mechanical properties and recommendations for the application of waste Bakelite aggregate concrete

Directory of Open Access Journals (Sweden)

Nopagon Usahanunth

2018-06-01

Full Text Available Bakelite waste from industrial manufacturing may be a hazard to the environment and public health. The utilization of waste Bakelite (WB to replace natural aggregates (NA, such as natural coarse aggregate (NCA and natural fine aggregate (NFA, in concrete and mortar is an approach for reducing both waste plastic and natural material. This research examines the utilization of waste Bakelite aggregate (WBA in concrete and mortar mixtures to form waste Bakelite aggregate concrete (WBAC and waste Bakelite mortar (WBM. The tests cover the physical and chemical properties of WBA, the mechanical properties of WBAC and WBM (including the extraction of chemical substances from WBA utilization to replace NCA and NFA, and recommendations for the application of replacement. The results indicate that WBA particles of different sizes can replace both fine and coarse natural aggregates. Its weight is less than natural aggregate but the absorption rate is higher. As for recommendations for the application, it was found that replacing 20% of NCA with waste Bakelite coarse aggregate in concrete (WBAC-RNCA was the most suitable proportion, owing to its mechanical properties and safety for the environment and public health, and because its material cost is acceptable. However, the use of waste Bakelite fine aggregate to replace NFA (WBAC-RNFA in concrete is not appropriate, because its mechanical properties are not sufficient, and it is considered unsafe for the environment and health. Moreover, WBM is not a suitable material for plastering work, since it may be a hazard to the environment and public health, and its cost is higher than conventional mortar. Keywords: Waste Bakelite, Aggregate, Concrete, Mortar

Behaviour of fibre reinforced concrete using steel slag coarse aggregate produced in Qatar

Directory of Open Access Journals (Sweden)

Alnahhal Wael

2017-01-01

Full Text Available The state of Qatar suffers from the shortage of natural resources needed for concrete production. Therefore, it is essential to investigate the feasibility of using by-product recycled materials as aggregates to maintain the concrete construction industry. Several types of recyclable materials are currently used in concrete. One of the potential resources of recycled concrete is steel slag. Knowing that Steel slag is the most significant solid waste generated by Qatar Steel Company in Qatar, replacing of natural coarse aggregate with steel slag aggregate will have a significant environmental and economic impact to the state of Qatar. This paper presents the compression and flexural test results of different concrete mixes made of steel slag coarse aggregate combined with a newly developed basalt chopped fibres. The parameters investigated included the volume fraction of the fibre used and the type of coarse aggregates (natural aggregates “Gabbro” and steel slag aggregates. Plain concrete specimens containing natural coarse aggregates and steel slag aggregates with no fibres added were also tested to serve as control. Test results showed that adding the basalt chopped fibres to the concrete mixes enhanced their flexural tensile strengths at different percentages. In addition, the compressive strength of concrete made with steel slag aggregate was higher than that made with natural gabbro aggregate. Test results clearly showed that steel slag aggregates can be used as sustainable and eco-friendly alternative materials in concrete structures.

An Investigation Into the Use of Groundnut as Fine Aggregate ...

African Journals Online (AJOL)

Physical properties of cement, groundnut shells and aggregates were determined. Concrete cubes measur- ing 150x150x150mm were cast. Groundnut shells were used to replace ne aggregate at 0, 5, 15, 25, 50 and 75% replacement levels. The e ects of the groundnut shells on the workability of fresh concrete were ...

Multi-factor Effects on the Durability of Recycle Aggregate Concrete

Science.gov (United States)

Ma, Huan; Cui, Yu-Li; Zhu, Wen-Yu; Xie, Xian-Jie

2016-05-01

Recycled Aggregate Concrete (RAC) was prepared with different recycled aggregate replacement ratio, 0, 30%, 70% and 100% respectively. The performances of RAC were examined by the freeze-thaw cycle, carbonization and sulfate attack to assess the durability. Results show that test sequence has different effects on the durability of RAC; the durability is poorer when carbonation experiment was carried out firstly, and then other experiment was carried out again; the durability is better when recycled aggregate replacement ratio is 70%.

Preliminary evaluation of physical and chemical characterization of waste palm oil shell as cool material replaced in asphaltic concrete as fine aggregate

Science.gov (United States)

Anuar, M. A. M.; Anting, N.; Shahidan, S.; Lee, Y. Y.; Din, M. F. Md; Khalid, F. S.; Nazri, W. M. H. W.

2017-11-01

Malaysia is one of the biggest producer of palm oil product and currently as main source of economy for the country. During the production of crude palm oil, a large amount of waste material is generated, such as palm oil fibres, palm oil shells and empty fruit bunches. Palm oil shell aggregate (POSA) is identified as a material that shows good potential to be used as a fine aggregate replacement in asphaltic concrete. On other hand, the chemical compound that exist in the Palm Oil Shell (POS) have shown a good potential as reflective component in cool-material. The purpose of this study is to obtain the physical and chemical properties of palm oil shell. The result shows the apparent particle density of Palm Oil Shell is 1.6 mg/m3. The specific gravity of palm oil shell was obtained with the value 1.6 and the water absorption amount of palm oil shell recorded from this study was 25.1%. The X-Ray Fluorescence study shows that palm oil shell contains the highest amount of SiO2 (46.412 wt%) and the second highest amount of Fe2O3 (34.016 wt%), both is the main output of relectivity compound. As a conclusion, waste palm oil shell has a potential to be used as alternative material for fine aggregate replacement. Besides that, the amount of chemical element that consist in palm oil shell which high in SiO2 and Fe2O3, promising the benefit to mitigate urban heat island as a cooling material agent.

Aggregation of Distributed Generation Assets in New York State: Appendix

Energy Technology Data Exchange (ETDEWEB)

2004-04-01

This report appendix describes aspects of a project to demonstrate the technical and economic feasibility of aggregating distributed generating resources in New York State. This project demonstrates a system that allows distributed generation (DG) to participate in competitive markets in much the same way as large central-station power plants. This approach involves aggregating the distributed demand-side resources into a single transaction entity consistent with the requirements of the New York Independent System Operator (NYISO). This single entity then buys or sells capacity and energy (i.e., curtailment) in NYISO markets.

Utilisation of iron ore tailings as aggregates in concrete

Directory of Open Access Journals (Sweden)

Francis Atta Kuranchie

2015-12-01

Full Text Available Sustainable handling of iron ore tailings is of prime concern to all stakeholders who are into iron ore mining. This study seeks to add value to the tailings by utilising them as a replacement for aggregates in concrete. A concrete mix of grade 40 MPa was prepared in the laboratory with water–cement ratio of 0.5. The concrete were cured for 1, 2, 3, 7, 14 and 28 days. The properties of the concrete such as workability, durability, density, compressive strength and indirect tensile strength were tested. A controlled mix of concrete was also prepared in similar way using conventional materials and the results were compared with the tailings concrete. It was found that the iron ore tailings may be utilised for complete replacement for conventional aggregates in concrete. The iron ore tailings aggregates concrete exhibited a good mechanical strength and even in the case of compressive strength, there was an improvement of 11.56% over conventional aggregates concrete. The indirect tensile strength did not improve against the control mix due high content of fines in the tailings aggregates but showed 4.8% improvement compared with the previous study where the conventional fine aggregates was partially replaced by 20% with iron ore tailings.

Physical mechanism for biopolymers to aggregate and maintain in non-equilibrium states.

Science.gov (United States)

Ma, Wen-Jong; Hu, Chin-Kun

2017-06-08

Many human or animal diseases are related to aggregation of proteins. A viable biological organism should maintain in non-equilibrium states. How protein aggregate and why biological organisms can maintain in non-equilibrium states are not well understood. As a first step to understand such complex systems problems, we consider simple model systems containing polymer chains and solvent particles. The strength of the spring to connect two neighboring monomers in a polymer chain is controlled by a parameter s with s → ∞ for rigid-bond. The strengths of bending and torsion angle dependent interactions are controlled by a parameter s A with s A  → -∞ corresponding to no bending and torsion angle dependent interactions. We find that for very small s A , polymer chains tend to aggregate spontaneously and the trend is independent of the strength of spring. For strong springs, the speed distribution of monomers in the parallel (along the direction of the spring to connect two neighboring monomers) and perpendicular directions have different effective temperatures and such systems are in non-equilibrium states.

Pre-Saturation Technique of the Recycled Aggregates: Solution to the Water Absorption Drawback in the Recycled Concrete Manufacture.

Science.gov (United States)

García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia Mª; Guerra-Romero, M Ignacio

2014-09-01

The replacement of natural aggregates by recycled aggregates in the concrete manufacturing has been spreading worldwide as a recycling method to counteract the large amount of construction and demolition waste. Although legislation in this field is still not well developed, many investigations demonstrate the possibilities of success of this trend given that concrete with satisfactory mechanical and durability properties could be achieved. However, recycled aggregates present a low quality compared to natural aggregates, the water absorption being their main drawback. When used untreated in concrete mix, the recycled aggregate absorb part of the water initially calculated for the cement hydration, which will adversely affect some characteristics of the recycled concrete. This article seeks to demonstrate that the technique of pre-saturation is able to solve the aforementioned problem. In order to do so, the water absorption of the aggregates was tested to determine the necessary period of soaking to bring the recycled aggregates into a state of suitable humidity for their incorporation into the mixture. Moreover, several concrete mixes were made with different replacement percentages of natural aggregate and various periods of pre-saturation. The consistency and compressive strength of the concrete mixes were tested to verify the feasibility of the proposed technique.

Impact of smart metering data aggregation on distribution system state estimation

OpenAIRE

Chen, Qipeng; Kaleshi, Dritan; Fan, Zhong; Armour, Simon

2016-01-01

Pseudo medium/low voltage (MV/LV) transformer loads are usually used as partial inputs to the distribution system state estimation (DSSE) in MV systems. Such pseudo load can be represented by the aggregation of smart metering (SM) data. This follows the government restriction that distribution network operators (DNOs) can only use aggregated SM data. Therefore, we assess the subsequent performance of the DSSE, which shows the impact of this restriction - it affects the voltage angle estimatio...

Influence of silica fume on mechanical and physical properties of recycled aggregate concrete

Directory of Open Access Journals (Sweden)

Özgür Çakır

2015-08-01

Full Text Available Several studies related to sustainable concrete construction have encouraged development of composite binders, involving Portland cement, industrial by-products, and concrete mixes with partial replacement of natural aggregate with recycled aggregate. In this paper, the effects of incorporating silica fume (SF in the concrete mix design to improve the quality of recycled aggregates in concrete are presented. Portland cement was replaced with SF at 0%, 5% and 10%. Specimens were manufactured by replacing natural aggregates with recycled aggregates. Two size fractions (4/12 mm and 8/22 mm as recycled aggregates were used and four series of concrete mixtures were produced. In all concrete mixtures, a constant water/binder ratio at 0.50 was used and concrete mixtures with a target initial slump of S4 class (16–21 cm were prepared. Concrete properties were evaluated by means of compressive strength, tensile splitting strength, water absorption and ultrasonic pulse velocity and it was found that, using 10% SF as a cement replacement for recycled aggregate concretes enhanced the mechanical and physical properties of concrete. At all the test ages the tensile splitting strength gain of the natural aggregate concrete mixture (NA with and without SF was higher than that of the recycled concrete mixtures. Continuous and significant improvement in the tensile splitting strength of recycled aggregate concretes incorporating SF was observed. Similar to compressive strength test results, concrete incorporating 10% SF and containing 4/12 mm fraction recycled aggregates showed better performance among recycled aggregate concretes.

Environmental suitability of recycled concrete aggregate in highways : [research summary].

Science.gov (United States)

2015-01-01

Natural highway aggregate is a finite resource that with continued use in construction : activities but some good quality aggregates used in existing concrete structures may be : re-used to replace with the natural aggregate. Due to the repair or rep...

Influence of recycled fine aggregates on the resistance of mortars to magnesium sulfate attack

International Nuclear Information System (INIS)

Lee, Seung-Tae

2009-01-01

The influence of recycled fine aggregates, which had been reclaimed from field-demolished concretes, on the resistance of mortar specimens to magnesium sulfate attack was investigated. Mortar specimens were prepared with recycled fine aggregates at different replacement levels (0%, 25%, 50%, 75% and 100% of natural fine aggregate by mass). The mortar specimens were exposed to 4.24% magnesium sulfate solution for about 1 year at ambient temperature, and regularly monitored for visual appearance, compressive strength loss and expansion. Additionally, in order to identify products of magnesium sulfate attack, mortar samples incorporating 0%, 25% and 100% replacement levels of the recycled fine aggregates were examined by X-ray diffraction (XRD) technique. Experimental results confirmed that the use of recycled fine aggregates up to a maximum 50% replacement level is effective under severe magnesium sulfate environment, irrespective of type of recycled fine aggregates. However, the worse performance was observed in mortar specimens incorporating 100% replacement level. It was found that the water absorption of recycled fine aggregates affected deterioration of mortar specimens, especially at a higher replacement level. XRD results indicated that the main cause of deterioration of the mortar specimens was primarily due to the formation of gypsum and thaumasite by magnesium sulfate attack. In addition, it appeared that the conversion of C-S-H into M-S-H by the attack probably influenced mechanical deterioration of mortar specimens with recycled fine aggregates.

Pre-Saturation Technique of the Recycled Aggregates: Solution to the Water Absorption Drawback in the Recycled Concrete Manufacture †

Science.gov (United States)

García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-del Pozo, Julia Mª; Guerra-Romero, M. Ignacio

2014-01-01

The replacement of natural aggregates by recycled aggregates in the concrete manufacturing has been spreading worldwide as a recycling method to counteract the large amount of construction and demolition waste. Although legislation in this field is still not well developed, many investigations demonstrate the possibilities of success of this trend given that concrete with satisfactory mechanical and durability properties could be achieved. However, recycled aggregates present a low quality compared to natural aggregates, the water absorption being their main drawback. When used untreated in concrete mix, the recycled aggregate absorb part of the water initially calculated for the cement hydration, which will adversely affect some characteristics of the recycled concrete. This article seeks to demonstrate that the technique of pre-saturation is able to solve the aforementioned problem. In order to do so, the water absorption of the aggregates was tested to determine the necessary period of soaking to bring the recycled aggregates into a state of suitable humidity for their incorporation into the mixture. Moreover, several concrete mixes were made with different replacement percentages of natural aggregate and various periods of pre-saturation. The consistency and compressive strength of the concrete mixes were tested to verify the feasibility of the proposed technique. PMID:28788188

Effect of Using Porcelanite as Partial Replacement of Fine Aggregate on Roller Compacted Concrete with Different Curing Methods

Directory of Open Access Journals (Sweden)

Abeer Abdulqader Salih

2016-09-01

Full Text Available Roller-Compacted Concrete is a no-slump concrete, with no reinforcing steel, no forms, no finishing and wet enough to support compaction by vibratory rollers. Due to the effect of curing on properties and durability of concrete, the main purpose of this research is to study the effect of various curing methods (air curing, 7 days water curing, and permanent water curing and porcelanite (local material used as an Internal Curing agent with different replacement percentages of fine aggregate (volumetric replacement on some properties of Roller-Compacted Concrete and to explore the possibility of introducing practical Roller-Compacted Concrete for road pavement with minimum requirement of curing. Specimens were sawed from slabs of (380*380*100 mm for determination of Ultrasonic Pulse Velocity (UPV and Voids volume. Results show that using (5 % porcelanite improved the results of UPV and Voids volume of Roller-Compacted Concrete (with air curing as compared with reference Roller-Compacted Concrete (with permanent water curing by percentages ranging from(3.6 to 28.9% and (-8 to -15.5% respectively.

Patterns of [PSI+] aggregation allow insights into cellular organization of yeast prion aggregates

Science.gov (United States)

Tyedmers, Jens

2012-01-01

The yeast prion phenomenon is very widespread and mounting evidence suggests that it has an impact on cellular regulatory mechanisms related to phenotypic responses to changing environments. Studying the aggregation patterns of prion amyloids during different stages of the prion life cycle is a first key step to understand major principles of how and where cells generate, organize and turn-over prion aggregates. The induction of the [PSI+] state involves the actin cytoskeleton and quality control compartments such as the Insoluble Protein Deposit (IPOD). An initially unstable transitional induction state can be visualized by overexpression of the prion determinant and displays characteristic large ring- and ribbon-shaped aggregates consisting of poorly fragmented bundles of very long prion fibrils. In the mature prion state, the aggregation pattern is characterized by highly fragmented, shorter prion fibrils that form aggregates, which can be visualized through tagging with fluorescent proteins. The number of aggregates formed varies, ranging from a single large aggregate at the IPOD to multiple smaller ones, depending on several parameters discussed. Aggregate units below the resolution of light microscopy that are detectable by fluorescence correlation spectroscopy are in equilibrium with larger aggregates in this stage and can mediate faithful inheritance of the prion state. Loss of the prion state is often characterized by reduced fragmentation of prion fibrils and fewer, larger aggregates. PMID:22449721

State-of-the-Art Fluorescence Fluctuation-Based Spectroscopic Techniques for the Study of Protein Aggregation.

Science.gov (United States)

Kitamura, Akira; Kinjo, Masataka

2018-03-23

Neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease, Parkinson's disease, and Huntington's disease, are devastating proteinopathies with misfolded protein aggregates accumulating in neuronal cells. Inclusion bodies of protein aggregates are frequently observed in the neuronal cells of patients. Investigation of the underlying causes of neurodegeneration requires the establishment and selection of appropriate methodologies for detailed investigation of the state and conformation of protein aggregates. In the current review, we present an overview of the principles and application of several methodologies used for the elucidation of protein aggregation, specifically ones based on determination of fluctuations of fluorescence. The discussed methods include fluorescence correlation spectroscopy (FCS), imaging FCS, image correlation spectroscopy (ICS), photobleaching ICS (pbICS), number and brightness (N&B) analysis, super-resolution optical fluctuation imaging (SOFI), and transient state (TRAST) monitoring spectroscopy. Some of these methodologies are classical protein aggregation analyses, while others are not yet widely used. Collectively, the methods presented here should help the future development of research not only into protein aggregation but also neurodegenerative diseases.

Effect of dynamic high pressure homogenization on the aggregation state of soy protein.

Science.gov (United States)

Keerati-U-Rai, Maneephan; Corredig, Milena

2009-05-13

Although soy proteins are often employed as functional ingredients in oil-water emulsions, very little is known about the aggregation state of the proteins in solution and whether any changes occur to soy protein dispersions during homogenization. The effect of dynamic high pressure homogenization on the aggregation state of the proteins was investigated using microdifferential scanning calorimetry and high performance size exclusion chromatography coupled with multiangle laser light scattering. Soy protein isolates as well as glycinin and beta-conglycinin fractions were prepared from defatted soy flakes and redispersed in 50 mM sodium phosphate buffer at pH 7.4. The dispersions were then subjected to homogenization at two different pressures, 26 and 65 MPa. The results demonstrated that dynamic high pressure homogenization causes changes in the supramolecular structure of the soy proteins. Both beta-conglycinin and glycinin samples had an increased temperature of denaturation after homogenization. The chromatographic elution profile showed a reduction in the aggregate concentration with homogenization pressure for beta-conglycinin and an increase in the size of the soluble aggregates for glycinin and soy protein isolate.

Distribution and Aggregate Thickness of Salt Deposits of the United States

Data.gov (United States)

U.S. Environmental Protection Agency — The map shows the distribution and aggregate thickness of salt deposits of the United States. This information is from contour map sheets, scanned and processed for...

Development of Ecoefficient Engineered Cementitious Composites Using Supplementary Cementitious Materials as a Binder and Bottom Ash Aggregate as Fine Aggregate

Directory of Open Access Journals (Sweden)

Jin Wook Bang

2015-01-01

Full Text Available The purpose of this study is to develop ecoefficient engineered cementitious composites (ECC using supplementary cementitious materials (SCMs, including fly ash (FA and blast furnace slag (SL as a binder material. The cement content of the ECC mixtures was replaced by FA and SL with a replacement rate of 25%. In addition, the fine aggregate of the ECC was replaced by bottom ash aggregate (BA with a substitution rate of 10%, 20%, and 30%. The influences of ecofriendly aggregates on fresh concrete properties and on mechanical properties were experimentally investigated. The test results revealed that the substitution of SCMs has an advantageous effect on fresh concrete’s properties; however, the increased water absorption and the irregular shape of the BA can potentially affect the fresh concrete’s properties. The substitution of FA and SL in ECC led to an increase in frictional bond at the interface between PVA fibers and matrix, improved the fiber dispersion, and showed a tensile strain capacity ranging from 3.3% to 3.5%. It is suggested that the combination of SCMs (12.5% FA and 12.5% SL and the BA aggregate with the substitution rate of 10% can be effectively used in ECC preparation.

Prevalence of Total Hip and Knee Replacement in the United States.

Science.gov (United States)

Maradit Kremers, Hilal; Larson, Dirk R; Crowson, Cynthia S; Kremers, Walter K; Washington, Raynard E; Steiner, Claudia A; Jiranek, William A; Berry, Daniel J

2015-09-02

Descriptive epidemiology of total joint replacement procedures is limited to annual procedure volumes (incidence). The prevalence of the growing number of individuals living with a total hip or total knee replacement is currently unknown. Our objective was to estimate the prevalence of total hip and total knee replacement in the United States. Prevalence was estimated using the counting method by combining historical incidence data from the National Hospital Discharge Survey and the Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases from 1969 to 2010 with general population census and mortality counts. We accounted for relative differences in mortality rates between those who have had total hip or knee replacement and the general population. The 2010 prevalence of total hip and total knee replacement in the total U.S. population was 0.83% and 1.52%, respectively. Prevalence was higher among women than among men and increased with age, reaching 5.26% for total hip replacement and 10.38% for total knee replacement at eighty years. These estimates corresponded to 2.5 million individuals (1.4 million women and 1.1 million men) with total hip replacement and 4.7 million individuals (3.0 million women and 1.7 million men) with total knee replacement in 2010. Secular trends indicated a substantial rise in prevalence over time and a shift to younger ages. Around 7 million Americans are living with a hip or knee replacement, and consequently, in most cases, are mobile, despite advanced arthritis. These numbers underscore the substantial public health impact of total hip and knee arthroplasties. Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated.

Influence of silica fume on mechanical and physical properties of recycled aggregate concrete

OpenAIRE

Çakır, Özgür; Sofyanlı, Ömer Özkan

2015-01-01

Several studies related to sustainable concrete construction have encouraged development of composite binders, involving Portland cement, industrial by-products, and concrete mixes with partial replacement of natural aggregate with recycled aggregate. In this paper, the effects of incorporating silica fume (SF) in the concrete mix design to improve the quality of recycled aggregates in concrete are presented. Portland cement was replaced with SF at 0%, 5% and 10%. Specimens were manufactured ...

Determination of the dynamic elastic constants of recycled aggregate concrete

Science.gov (United States)

Tsoumani, A. A.; Barkoula, N.-M.; Matikas, T. E.

2015-03-01

Nowadays, construction and demolition waste constitutes a major portion of the total solid waste production in the world. Due to both environmental and economical reasons, an increasing interest concerning the use of recycled aggregate to replace aggregate from natural sources is generated. This paper presents an investigation on the properties of recycled aggregate concrete. Concrete mixes are prepared using recycled aggregates at a substitution level between 0 and 100% of the total coarse aggregate. The influence of this replacement on strengthened concrete's properties is being investigated. The properties estimated are: density and dynamic modulus of elasticity at the age of both 7 and 28 days. Also, flexural strength of 28 days specimens is estimated. The determination of the dynamic elastic modulus was made using the ultrasonic pulse velocity method. The results reveal that the existence of recycled aggregates affects the properties of concrete negatively; however, in low levels of substitution the influence of using recycled aggregates is almost negligible. Concluding, the controlled use of recycled aggregates in concrete production may help solve a vital environmental issue apart from being a solution to the problem of inadequate concrete aggregates.

Durability Indicators in High Absorption Recycled Aggregate Concrete

Directory of Open Access Journals (Sweden)

Luis F. Jiménez

2015-01-01

Full Text Available The use of recycled aggregates in structural concrete production has the inconvenience of increasing the fluid transport properties, such as porosity, sorptivity, and permeability, which reduces the resistance against penetration of environmental loads such as carbon dioxide and chloride ion. In this paper, behavior of ten concrete mixtures with different percentages of coarse aggregate replacement was studied. The recycled material was recovered by crushing of concrete rubble and had high absorption values. The results showed that it is possible to achieve good resistance to carbonation and chloride penetration with up to 50% replacement of recycled coarse aggregate for 0.5 water/cement ratio. Finally, new indexes for porosity and sorptivity were proposed to assess the quality of concrete.

Optimal replacement policy for safety-related multi-component multi-state systems

International Nuclear Information System (INIS)

Xu Ming; Chen Tao; Yang Xianhui

2012-01-01

This paper investigates replacement scheduling for non-repairable safety-related systems (SRS) with multiple components and states. The aim is to determine the cost-minimizing time for replacing SRS while meeting the required safety. Traditionally, such scheduling decisions are made without considering the interaction between the SRS and the production system under protection, the interaction being essential to formulate the expected cost to be minimized. In this paper, the SRS is represented by a non-homogeneous continuous time Markov model, and its state distribution is evaluated with the aid of the universal generating function. Moreover, a structure function of SRS with recursive property is developed to evaluate the state distribution efficiently. These methods form the basis to derive an explicit expression of the expected system cost per unit time, and to determine the optimal time to replace the SRS. The proposed methodology is demonstrated through an illustrative example.

Study on conversion relationships of compressive strength indexes for recycled lightweight aggregate concrete

Science.gov (United States)

Zhang, Xiang-gang; Yang, Jian-hui; Kuang, Xiao-mei

2017-01-01

In order to study cube compressive strength and axial compressive strength of recycled lightweight aggregate concrete(RLAC), and conversion relationship between the two, with the replacement rate of recycled lightweight coarse aggregate as change parameters, 15 standard cube test specimens and 15 standard prism test specimens were produced to carry out the test. Then compressive strength of test specimens were measured, and the law of different replacement rate of recycled lightweight coarse aggregate influencing compressive strength of RLAC was analyzed, as the method of statistical regression adopted, the conversion relationships between of cube compressive strength and axial compressive strength of RLAC was obtained. It is shown that compressive strength of RLAC are lower than compressive strength of ordinary concrete; and that compressive strength of RLAC gradually decreases as replacement rate of recycled lightweight coarse aggregate increases; as well as, the conversion relationship between axial compressive strength and cube compressive strength of RLAC is different from ordinary concrete; based on the experimental data, conversion relationship formula between compressive strength indexes of RLAC was established. It is suggested that the replacement rate of recycled lightweight aggregate should be controlled within 25%.

Utilization of recycled glass as aggregate in controlled low-strength material (CLSM)

Energy Technology Data Exchange (ETDEWEB)

Ohlheiser, T.R. [Western Mobile Denver Aggregate Div., CO (United States)

1998-10-01

Incoming glass from curbside recycling programs is successfully being utilized as aggregate replacements. The colored glass that can not be used by local bottle manufacturers is crushed to a {1/2} in. (12.5 mm) material and used in various construction projects. The most successful use of processed glass aggregate (PGA) to date, has been in replacing up to 100% of the aggregate in controlled low-strength material (CLSM). It has proven to be successful and has gained acceptance by contractors in the Boulder, Colorado area.

Metabolic states following accumulation of intracellular aggregates: implications for neurodegenerative diseases.

Directory of Open Access Journals (Sweden)

Alexei Vazquez

Full Text Available The formation of intracellular aggregates is a common etiology of several neurodegenerative diseases. Mitochondrial defects and oxidative stress has been pointed as the major mechanistic links between the accumulation of intracellular aggregates and cell death. In this work we propose a "metabolic cell death by overcrowding" as an alternative hypothesis. Using a model of neuron metabolism, we predict that as the concentration of protein aggregates increases the neurons transit through three different metabolic phases. The first phase (0-6 mM corresponds with the normal neuron state, where the neuronal activity is sustained by the oxidative phosphorylation of lactate. The second phase (6-8.6 mM is characterized by a mixed utilization of lactate and glucose as energy substrates and a switch from ammonia uptake to ammonia release by neurons. In the third phase (8.6-9.3 mM neurons are predicted to support their energy demands from glycolysis and an alternative pathway for energy generation, involving reactions from serine synthesis, one carbon metabolism and the glycine cleavage system. The model also predicts a decrease in the maximum neuronal capacity for energy generation with increasing the concentration of protein aggregates. Ultimately this maximum capacity becomes zero when the protein aggregates reach a concentration of about 9.3 mM, predicting the cessation of neuronal activity.

The effect of limestone aggregate porosity and saturation degree on the interfacial zone

International Nuclear Information System (INIS)

Nguyen, T.D.; Le Saout, G.; Devillers, P.; Garcia-Diaz, E.

2015-01-01

The recycling of concrete wastes concerns the nuclear industry as many nuclear facilities will have to be dismantled and the reduction and reuse of the decommissioning concrete wastes in order to minimize the total waste volume is a key issue. The recycled aggregates have the potential to replace natural resources however it is necessary to assess the effect of recycled aggregates on the final concrete. One important issue to be addressed to achieve the required mechanical properties is the water absorption of the recycled aggregates. As a first step, we have used in this study limestone aggregates with different porosities (total porosity from 2 to 20 %) and have investigated the influence of the porosity and the initial saturation degree of these aggregates on the porosity of the interfacial transition zone (ITZ) using scanning electron microscope. The equation of Feret for the strength-porosity relationship of our mortars was applied σ = K(100-p) 2 where σ is the compressive strength in MPa, p is the capillary pore volume in % and K a constant. Aggregates with lower porosity follow the same law characterized by a K value higher than the value for the more porous aggregate law. The K parameter is not dependent of the humidity degree of the aggregate: for a given aggregate, family mortars made with dry and wet aggregate follow the same law. But for porous aggregates as the meso-porosity of the ITZ for a given time of hydration is higher for mortars made with wet aggregates, the compressive strength of these mortars is less than those of mortars made with dry aggregates. Contrary to the low porous aggregate, it was not possible for porous limestone aggregates, and with a calculation based on the saturated surface dry state as reference state to obtain the same net water to cement ratio with wet and dry aggregates. This study reflects the difficulty to control the amount of efficient water in concrete when using porous aggregates and its influence on compressive

Overview of studies on the effect of recycled aggregates sourced from tested cylinders on concrete material and structural properties

Directory of Open Access Journals (Sweden)

Bilal Hamad

2017-01-01

Full Text Available The paper presents an overview of a two-phase research program that was designed at the American University of Beirut (AUB to investigate the effect of replacing different percentages of natural coarse aggregates (NCA with recycled coarse aggregates (RCA on the properties of the produced concrete. The source of RCA was tested cylinders in batching plants which would help recycling and reusing portion of the waste products of the concrete industry. In the first phase, the fresh and hardened mechanical properties of the produced concrete mix were investigated. The variables were the concrete strength (28 or 60 MPa and the percentage replacement of NCA with RCA from crushed tested cylinders [0 (control, 20, 40, 60, 80, or 100%. Normal strength tested cylinders were used as source of the recycled aggregates for the normal strength concrete (NSC mix and high strength tested cylinders were used for the high strength concrete (HSC mix. Tests included plastic state slump and hardened state mechanical properties including cylinder compressive strength, cylinder splitting tensile strength, modulus of elasticity, and standard beams flexural strength. The results indicated no significant effect on the slump and around 10% average reduction in the hardened mechanical properties for both investigated levels of concrete compressive strength. In the second phase, the structural behavior of normal strength concrete (NSC reinforced concrete beams prepared by replacing different percentages of NCA with RCA from tested concrete cylinders was studied. For each of three modes of failure (flexural, shear, or bond splitting, three beams with different percentages replacement [0 (control, 40, or 100 percent] were tested. One replicate was prepared for each beam to validate the test results. Results indicated no significant difference in the ultimate load reached or load-deflection behavior that could be related to the percentage replacement of NCA with RCA.

Chapter K: Progress in the Evaluation of Alkali-Aggregate Reaction in Concrete Construction in the Pacific Northwest, United States and Canada

Science.gov (United States)

Shrimer, Fred H.

2005-01-01

The supply of aggregates suitable for use in construction and maintenance of infrastructure in western North America is a continuing concern to the engineering and resources-management community. Steady population growth throughout the region has fueled demand for high-quality aggregates, in the face of rapid depletion of existing aggregate resources and slow and difficult permitting of new sources of traditional aggregate types. In addition to these challenges, the requirement for aggregates to meet various engineering standards continues to increase. In addition to their physical-mechanical properties, other performance characteristics of construction aggregates specifically depend on their mineralogy and texture. These properties can result in deleterious chemical reactions when aggregate is used in concrete mixes. When this chemical reaction-termed 'alkali-aggregate reaction' (AAR)-occurs, it can pose a major problem for concrete structures, reducing their service life and requiring expensive repair or even replacement of the concrete. AAR is thus to be avoided in order to promote the longevity of concrete structures and to ensure that public moneys invested in infrastructure are well spent. Because the AAR phenomenon is directly related to the mineral composition, texture, and petrogenesis of the rock particles that make up aggregates, an understanding of the relation between the geology and the performance of aggregates in concrete is important. In the Pacific Northwest, some aggregates have a moderate to high AAR potential, but many others have no or only a low AAR potential. Overall, AAR is not as widespread or serious a problem in the Pacific Northwest as in other regions of North America. The identification of reactive aggregates in the Pacific Northwest and the accurate prediction of their behavior in concrete continue to present challenges for the assessment and management of geologic resources to the owners and operators of pits and quarries and to the

Recycled Concrete as Aggregate for Structural Concrete Production

OpenAIRE

Mirjana Malešev; Vlastimir Radonjanin; Snežana Marinković

2010-01-01

A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC) as a control concrete and two types of concrete made with natural fine and recycle...

Spectroscopic investigation of the aggregation state of amphotericin B during loading, freeze-drying, and reconstitution of polymeric micelles.

Science.gov (United States)

Adams, Monica; Kwon, Glen S

2004-11-22

To investigate the relative aggregation state of amphotericin B (AmB) during loading and reconstitution of polymeric micelles. Hexanoate and stearate derivatives of PEO-b-p (L-Asp) were prepared. The polymers and AmB were dissolved in methanol (MeOH). Milli-Q water was then added slowly, and the MeOH was removed via rotary evaporation. The solutions were freeze-dried in the presence of trehalose. During micelle preparation, the aggregation state of AmB was assessed using absorption spectroscopy. Upon reconstitution, the samples were analyzed using vapor-pressure osmometry, size-exclusion chromatography (SEC), and absorption spectroscopy. The absorption spectrum of AmB in the presence of the block copolymers was compared to that of AmB alone under the same conditions. AmB was loaded into micelles prepared from acyl derivatives of PEO-b-p (L-Asp). Absorption spectroscopy indicated that the aggregation state was preserved during the loading process. AmB exists in a self-aggregated state in polymeric micelles containing hexanoate ester cores and in a relatively monomeric state in polymeric micelles containing stearate ester cores. Vapor-pressure osmometry confirmed the isotonicity of the formulations, while SEC indicated that the micelles were approximately 10(6) g/mol. Depending on the polymer structure and assembly conditions, it is possible to encapsulate AmB in a relatively nonaggregated or aggregated state in micelles prepared from acyl derivatives of PEO-b-p (L-Asp). In polymeric micelles containing stearate side chains, AmB was loaded in a nearly monomeric state, possibly due to interaction with the stearate side chains. The final aggregation state of the drug is preserved during lyophilization and reconstitution of polymeric micelles prepared by a novel solvent evaporation procedure.

Influence of Waste Brick Powder in the Mechanical Properties of Recycled Aggregate Concrete

Directory of Open Access Journals (Sweden)

Viviana Letelier

2018-03-01

Full Text Available Brick and concrete are the main materials contributing to demolition and construction waste. Considering this precedent, the effects of using both residuals in medium strength concretes are analyzed. Waste brick powder is used as a cement replacement in three different levels: 5%, 10%, and 15%, and it is tested in concretes with no recycled aggregates and concretes with 30% of recycled coarse aggregates replacing natural ones. The compressive strength, the flexural strength, and modulus of elasticity are calculated and compared to a control concrete with no brick powder and no recycled aggregates. The effects of the simultaneous use of both residuals on the physical properties of the recycled concrete are highlighted. Results show that 15% of cement can be replaced by waste brick powder together with 30% of recycled aggregates without suffering significant losses in the strength of the final material when compared to a control concrete.

Strength Characteristics of Quarry Dust in Replacement of Sand

Science.gov (United States)

Shyam Prakash, K.; Hanumantha Rao, Ch, Dr

2017-08-01

The replacement of natural fine aggregate by using quarry dust leads to consumption of generated quarry dust, the requirement of land fill area can be reduced and solves the natural sand scarcity problem. The sand availability as a fine aggregate at low cost which needs the reason to search as a alternative material. Even it causes saddle to dump the crusher dust at one place which causes environmental pollution. The chemical analysis, specific gravity, sieve analysis and compressive strength is identified for various percentage and grades of concrete by replacement of sand with quarry dust.

Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates

KAUST Repository

Zhao, Kui

2016-07-13

We demonstrate that local and long range orders of poly(3-hexylthiophene) (P3HT) semicrystalline films can be synergistically improved by combining chemical functionalization of the dielectric surface with solution-state disentanglement and pre-aggregation of P3HT in a theta solvent, leading to a very significant enhancement of the field effect carrier mobility. The pre-aggregation and surface functionalization effects combine to enhance the carrier mobility nearly 100-fold as compared with standard film preparation by spin-coating, and nearly 10-fold increase over the benefits of pre-aggregation alone. In situ quartz crystal microbalance with dissipation (QCM-D) experiments reveal enhanced deposition of pre-aggregates on surfaces modified with an alkyl-terminated self-assembled monolayer (SAM) in comparison to un-aggregated polymer chains. Additional investigations reveal the combined pre-aggregation and surface functionalization significantly enhances local order of the conjugated polymer through planarization and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining complementary routes, such as well-known pre-aggregation with substrate chemical functionalization, to enhance the polymer self-assembly and improve its interfacial order with benefits for transport properties.

Feasibility Studies of Palm Oil Mill Waste Aggregates for the Construction Industry

Directory of Open Access Journals (Sweden)

Jegathish Kanadasan

2015-09-01

Full Text Available The agricultural industry in Malaysia has grown rapidly over the years. Palm oil clinker (POC is a byproduct obtained from the palm oil industry. Its lightweight properties allows for its utilization as an aggregate, while in powder form as a filler material in concrete. POC specimens obtained throughout each state in Malaysia were investigated to evaluate the physical, chemical, and microstructure characteristics. Variations between each state were determined and their possible contributory factors were assessed. POC were incorporated as a replacement material for aggregates and their engineering characteristics were ascertained. Almost 7% of density was reduced with the introduction of POC as aggregates. A sustainability assessment was made through greenhouse gas emission (GHG and cost factor analyses to determine the contribution of the addition of POC to the construction industry. Addition of POC helps to lower the GHG emission by 9.6% compared to control specimens. By channeling this waste into the construction industry, an efficient waste-management system can be promoted; thus, creating a cleaner environment. This study is also expected to offer some guides and directions for upcoming research works on the incorporation of POC.

Feasibility Studies of Palm Oil Mill Waste Aggregates for the Construction Industry

Science.gov (United States)

Kanadasan, Jegathish; Ahmad Fauzi, Auni Filzah; Abdul Razak, Hashim; Selliah, Paramananthan; Subramaniam, Vijaya; Yusoff, Sumiani

2015-01-01

The agricultural industry in Malaysia has grown rapidly over the years. Palm oil clinker (POC) is a byproduct obtained from the palm oil industry. Its lightweight properties allows for its utilization as an aggregate, while in powder form as a filler material in concrete. POC specimens obtained throughout each state in Malaysia were investigated to evaluate the physical, chemical, and microstructure characteristics. Variations between each state were determined and their possible contributory factors were assessed. POC were incorporated as a replacement material for aggregates and their engineering characteristics were ascertained. Almost 7% of density was reduced with the introduction of POC as aggregates. A sustainability assessment was made through greenhouse gas emission (GHG) and cost factor analyses to determine the contribution of the addition of POC to the construction industry. Addition of POC helps to lower the GHG emission by 9.6% compared to control specimens. By channeling this waste into the construction industry, an efficient waste-management system can be promoted; thus, creating a cleaner environment. This study is also expected to offer some guides and directions for upcoming research works on the incorporation of POC. PMID:28793579

Feasibility Studies of Palm Oil Mill Waste Aggregates for the Construction Industry.

Science.gov (United States)

Kanadasan, Jegathish; Fauzi, Auni Filzah Ahmad; Razak, Hashim Abdul; Selliah, Paramananthan; Subramaniam, Vijaya; Yusoff, Sumiani

2015-09-22

The agricultural industry in Malaysia has grown rapidly over the years. Palm oil clinker (POC) is a byproduct obtained from the palm oil industry. Its lightweight properties allows for its utilization as an aggregate, while in powder form as a filler material in concrete. POC specimens obtained throughout each state in Malaysia were investigated to evaluate the physical, chemical, and microstructure characteristics. Variations between each state were determined and their possible contributory factors were assessed. POC were incorporated as a replacement material for aggregates and their engineering characteristics were ascertained. Almost 7% of density was reduced with the introduction of POC as aggregates. A sustainability assessment was made through greenhouse gas emission (GHG) and cost factor analyses to determine the contribution of the addition of POC to the construction industry. Addition of POC helps to lower the GHG emission by 9.6% compared to control specimens. By channeling this waste into the construction industry, an efficient waste-management system can be promoted; thus, creating a cleaner environment. This study is also expected to offer some guides and directions for upcoming research works on the incorporation of POC.

Utilisation of Waste Marble Dust as Fine Aggregate in Concrete

Science.gov (United States)

Vigneshpandian, G. V.; Aparna Shruthi, E.; Venkatasubramanian, C.; Muthu, D.

2017-07-01

Concrete is the important construction material and it is used in the construction industry due to its high compressive strength and its durability. Now a day’s various studies have been conducted to make concrete with waste material with the intention of reducing cost and unavailability of conventional materials. This paper investigates the strength properties of concrete specimens cast using waste marble dust as replacement of fine aggregate. The marble pieces are finely crushed to powdered and the gradation is compared with conventional fine aggregate. Concrete specimen were cast using wmd in the laboratory with different proportion (25%, 50% and 100%) by weight of cement and from the studies it reveals that addition of waste marble dust as a replacement of fine aggregate marginally improves compressive, tensile and flexural strength in concrete.

Effect of Fly-Ash on Corrosion Resistance Characteristics of Rebar Embedded in Recycled Aggregate Concrete

Science.gov (United States)

Revathi, Purushothaman; Nikesh, P.

2018-04-01

In the frame of an extended research programme dealing with the utilization of recycled aggregate in concrete, the corrosion resistance characteristics of rebars embedded in recycled aggregate concrete is studied. Totally five series of concrete mixtures were prepared with fly-ash as replacement for cement in the levels of 10-30% by weight of cement. Corrosion studies by 90 days ponding test, linear polarization test and impressed voltage tests were carried out, in order to investigate whether corrosion behaviour of the rebars has improved due to the replacement of cement with fly-ash. Results showed that the replacement of cement with fly-ash in the range of 20-30% improves the corrosion resistance characteristics of recycled aggregate concrete.

The effect of recycled concrete aggregate properties on the bond strength between RCA concrete and steel reinforcement

International Nuclear Information System (INIS)

Butler, L.; West, J.S.; Tighe, S.L.

2011-01-01

The purpose of this study was to investigate the influence that replacing natural coarse aggregate with recycled concrete aggregate (RCA) has on concrete bond strength with reinforcing steel. Two sources of RCA were used along with one natural aggregate source. Numerous aggregate properties were measured for all aggregate sources. Two types of concrete mixture proportions were developed replacing 100% of the natural aggregate with RCA. The first type maintained the same water-cement ratios while the second type was designed to achieve the same compressive strengths. Beam-end specimens were tested to determine the relative bond strength of RCA and natural aggregate concrete. On average, natural aggregate concrete specimens had bond strengths that were 9 to 19% higher than the equivalent RCA specimens. Bond strength and the aggregate crushing value seemed to correlate well for all concrete types.

Properties of Non-Structural Concrete Made with Mixed Recycled Aggregates and Low Cement Content.

Science.gov (United States)

López-Uceda, Antonio; Ayuso, Jesús; López, Martin; Jimenez, José Ramón; Agrela, Francisco; Sierra, María José

2016-01-26

In spite of not being legally accepted in most countries, mixed recycled aggregates (MRA) could be a suitable raw material for concrete manufacturing. The aims of this research were as follows: (i) to analyze the effect of the replacement ratio of natural coarse aggregates with MRA, the amount of ceramic particles in MRA, and the amount of cement, on the mechanical and physical properties of a non-structural concrete made with a low cement content; and (ii) to verify if it is possible to achieve a low-strength concrete that replaces a greater amount of natural aggregate with MRA and that has a low cement content. Two series of concrete mixes were manufactured using 180 and 200 kg/m³ of CEM II/A-V 42.5 R type Portland cement. Each series included seven concrete mixes: one with natural aggregates; two MRA with different ceramic particle contents; and one for each coarse aggregate replacement ratio (20%, 40%, and 100%). To study their properties, compressive and splitting tensile strength, modulus of elasticity, density, porosity, water penetration, and sorptivity, tests were performed. The results confirmed that the main factors affecting the properties analyzed in this research are the amount of cement and the replacement ratio; the two MRAs used in this work presented a similar influence on the properties. A non-structural, low-strength concrete (15 MPa) with an MRA replacement ratio of up to 100% for 200 kg/m³ of cement was obtained. This type of concrete could be applied in the construction of ditches, sidewalks, and other similar civil works.

Properties of concrete with tire derived aggregate and crumb rubber as a lighthweight substitute for mineral aggregates in the concrete mix

Science.gov (United States)

Siringi, Gideon Momanyi

Scrap tires continue to be a nuisance to the environment and this research proposes one way of recycling them as a lightweight aggregate which can substitute for mineral aggregates in concrete. Aggregates derived from scrap tires are often referred to as Tire Derived Aggregate (TDA). First, the focus is how much mineral aggregate can be replaced by these waste tires and how the properties of concrete are affected with the introduction of rubber. This is being mindful of the fact that for a new material to be acceptable as an engineering material, its properties and behavior has to be well understood, the materials must perform properly and be acceptable to the regulating agencies. The role played by the quantity of TDA and Crumb Rubber replacing coarse aggregate and fine aggregate respectively as well as different treatment and additives in concrete on its properties are examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, Splitting Tensile Strength based on ASTM C496, Modulus of Rupture (flexural strength) based on ASTM C78 and Bond strength of concrete developed with reinforcing steel based on ASTM C234.Through stress-strain plots, the rubberized concrete is compared in terms of change in ductility, toughness and Elastic Modulus. Results indicate that while replacement of mineral aggregates with TDA results in reduction in compressive strength, this may be mitigated by addition of silica fume or using a smaller size of TDA to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product with lower density while utilizing recycled TDA. From the results, it is observed that 7-10% of weight of mineral aggregates can be replaced by an equal volume of TDA to produce concrete with compressive strength of up to 4000 psi (27.5 MPa). Rubberized concrete would have higher ductility and toughness with

New Insights on US Aggregate and State Level Trade with the China Region%New Insights on US Aggregate and State Level Trade with the China Region

Institute of Scientific and Technical Information of China (English)

Catherine Y. Co

2011-01-01

Aggregate trade data with breakdown into related and non-related party components show that US multinational enterprises use different trading strategies in the China region relative to other countries. US trade with the China region in 2002-007 is characterized by arm ＇s- length transactions. State-level trade data show great variability in state engagement with the region through trade： exports to the region range from 1 to 28 percent of state exports. In addition, compared to exports to other countries, exports to the region are highly concentrated. At the extreme, for some states, 96-98 percent of exports to the region are computer and electronic products. Finally, gravity regressions show that state exports to Hong Kong are posflively associated with the relative size of the ltong Kong-born population in the states. There is no evidence that stricter labor regimes lead to lower state exports.

Acid resistance of quaternary blended recycled aggregate concrete

Directory of Open Access Journals (Sweden)

K Jagannadha Rao

2018-06-01

Full Text Available The possibility of reusing the aggregate from demolished structures in fresh concrete, in order to reduce the CO2 impact on the environment [23] and to preserve natural resources, was explored worldwide and it is established that recycled aggregates can be used as a partial replacement of natural aggregates. Due to its potential to be used in eco-friendly structures and shortage of supply of natural aggregates in some parts of the world, there is an increasing interest in using the recycled aggregate. The durability aspects are also of equal concern along with the strength and economy of any material to be used in the construction. Studies reveal that the behaviour of ternary and quaternary blended concretes is superior from durability point of view compared to conventional concrete. Therefore a study is conducted to assess the acid resistance of recycled aggregate based Quaternary Blended Cement Concrete (QBCC of two grades M40 and M60. Fly ash and silica fume are fixed at 20% and 10% respectively from the previous studies while two percentages of Nano silica (2 and 3% were used along with the cement to obtain QBCC. Three percentages of recycled aggregates as partial replacement of conventional aggregate (0%, 50% and 75% were used in this study. Two different acids (HCL and H2SO4 with different concentrations (3 and 5% were used in this study. Acid resistance of QBCC with Recycled Concrete Aggregate (RCA is assessed in terms of visual appearance, weight loss, and compressive strength loss by destructive and non-destructive tests at regular intervals for a period of 56 days. The test results showed marginal weight loss and strength loss in both M40 and M60 grades of concretes. The Ultrasonic Pulse Velocity (UPV results show that the quality of QBCC is good even after being subjected to acid exposure. Keywords: Recycled concrete aggregate (RCA, Quaternary blended cement concrete (QBCC, Acid resistance, Ultrasonic pulse velocity (UPV, Mineral

Physical and mechanical properties of mortars containing PET and PC waste aggregates.

Science.gov (United States)

Hannawi, Kinda; Kamali-Bernard, Siham; Prince, William

2010-11-01

Non-biodegradable plastic aggregates made of polycarbonate (PC) and polyethylene terephthalate (PET) waste are used as partial replacement of natural aggregates in mortar. Various volume fractions of sand 3%, 10%, 20% and 50% are replaced by the same volume of plastic. This paper investigates the physical and mechanical properties of the obtained composites. The main results of this study show the feasibility of the reuse of PC and PET waste aggregates materials as partial volume substitutes for natural aggregates in cementitious materials. Despite of some drawbacks like a decrease in compressive strength, the use of PC and PET waste aggregates presents various advantages. A reduction of the specific weight of the cementitious materials and a significant improvement of their post-peak flexural behaviour are observed. The calculated flexural toughness factors increase significantly with increasing volume fraction of PET and PC-aggregates. Thus, addition of PC and PET plastic aggregates in cementitious materials seems to give good energy absorbing materials which is very interesting for several civil engineering applications like structures subjected to dynamic or impact efforts. The present study has shown quite encouraging results and opened new way for the recycling of PC waste aggregate in cement and concrete composites. Copyright © 2010 Elsevier Ltd. All rights reserved.

Effect of porosity on physical properties of lightweight cement composite with foamed glass aggregate

Directory of Open Access Journals (Sweden)

Kurpińska Marzena

2017-01-01

Full Text Available This paper reports on a study of physical properties of lightweight cement composite. We investigate the possibility of replacing traditional aggregate with Granulated Ash Aggregate (GAA and above all with Granulated Expanded Glass Aggregate (GEGA. For this purpose, 15 specimens of different percentage share of each aggregate in total aggregate volume were tested: 0%, 25%, 50%, 75% or 100% of foam glass aggregate (GEGA partially replaced by ash aggregate (GAA content in the cement composite. The water-cement ratio was constant and equal to w/c=0.5. Three grain sizes were analyzed: 2mm, 4mm (both GEGA and 8mm (GAA. Numerical simulations of concrete specimen behavior under static loading were conducted with the implementation of elastic plastic model of each component. The study shows a significant impact of grain type and size on physical properties of lightweight concrete. Due to lower density of foamed glass aggregate, specimens shows various apparent density and porosity, which affect concrete properties. Compressive strength of concrete decreases with the increase in foam glass aggregate content; however specimens show different workability and in consequence porosity of lightweight concrete.

Properties of cold-bonded lightweight artificial aggregate containing bottom ash with different curing regime

Science.gov (United States)

Mohamad Ibrahim, Norlia; Nizar Ismail, Khairul; Che Amat, Roshazita; Mohamad Ghazali, Mohamad Iqbal

2018-03-01

Cold-bonded pelletizing technique is frequently used in aggregate manufacturing process as it can minimise the energy consumption. It has contributed to both economical and environmental advantages because it helps to reduce the gas emissions problems. Bottom ash collected from municipal solid waste incineration (MSWI) plant was selected as raw material in this study and was utilised as a partial replacement for cement for artificial aggregate production. Several percentage of ash replacement was selected ranged from 10 to 50%. Aggregate pellets were subjected to different types of curing condition which is room-water (RW), room-room (RR), oven-room (OR) and oven-water (OW) condition. Properties of aggregate pellets were examined to obtain its density, water absorption, aggregate impact value (AIV) and specific gravity (SG). The results indicated that the most efficient curing regime is by exposing the aggregate in RW condition. The optimum aggregate was selected at 20% where it has satisfied the required density of 739.5kg/m3, and classified as strong aggregate with AIV 14. However, the water absorption of aggregate increased proportionately with the increment of ash content.

Evaluation of using crushed brick as coarse aggregate in concrete layer within rigid highway pavement

Directory of Open Access Journals (Sweden)

Alwash Ali

2018-01-01

Full Text Available Most of the present studies related to the field of highway pavement construction technique tend to make use of the local available materials as substitutes for the imported and necessary materials for some of the practical application. For this reason this research aims at looking for the prospect of used locally available aggregate such as crushed clay bricks for the aim of producing proper concrete with suitable thermal and mechanical properties. Experimental investigations have been carried out to asses the effect of partial replacement of coarse aggregate by free manually crushed Brick with percentages (10, 20, 30 and 40% of virgin coarse aggregate in concrete mix for highway rigid pavement. While the percentage (0% replacement represent reference mix. Mix proportion based on the target of compressive strength for all replacement percentage of (33 MPa at (28 days to achieve AASHTO requirement for highway concrete rigid pavement .The results of flexural strength, modulus of elasticity, density and thermal conductivity refers to better performance (less thickness of concrete layer with large spacing between contraction or expansion joints and less stresses due to warping induced concrete layer for concrete mix with 20% crushed brick as replacement of coarse aggregate.

Properties of Non-Structural Concrete Made with Mixed Recycled Aggregates and Low Cement Content

Science.gov (United States)

López-Uceda, Antonio; Ayuso, Jesús; López, Martin; Jimenez, José Ramón; Agrela, Francisco; Sierra, María José

2016-01-01

In spite of not being legally accepted in most countries, mixed recycled aggregates (MRA) could be a suitable raw material for concrete manufacturing. The aims of this research were as follows: (i) to analyze the effect of the replacement ratio of natural coarse aggregates with MRA, the amount of ceramic particles in MRA, and the amount of cement, on the mechanical and physical properties of a non-structural concrete made with a low cement content; and (ii) to verify if it is possible to achieve a low-strength concrete that replaces a greater amount of natural aggregate with MRA and that has a low cement content. Two series of concrete mixes were manufactured using 180 and 200 kg/m3 of CEM II/A-V 42.5 R type Portland cement. Each series included seven concrete mixes: one with natural aggregates; two MRA with different ceramic particle contents; and one for each coarse aggregate replacement ratio (20%, 40%, and 100%). To study their properties, compressive and splitting tensile strength, modulus of elasticity, density, porosity, water penetration, and sorptivity, tests were performed. The results confirmed that the main factors affecting the properties analyzed in this research are the amount of cement and the replacement ratio; the two MRAs used in this work presented a similar influence on the properties. A non-structural, low-strength concrete (15 MPa) with an MRA replacement ratio of up to 100% for 200 kg/m3 of cement was obtained. This type of concrete could be applied in the construction of ditches, sidewalks, and other similar civil works. PMID:28787874

Aggregate resource availability in the conterminous United States, including suggestions for addressing shortages, quality, and environmental concerns

Science.gov (United States)

Langer, William H.

2011-01-01

One-third of America's major roads are in poor or mediocre condition, and over one-quarter of the bridges are either structurally deficient or functionally obsolete. A 70-percent increase in annual aggregate production may be required to upgrade the transportation infrastructure. Natural aggregate is widespread throughout the conterminous United States, but the location of aggregate is determined by geology and is non-negotiable. Natural aggregate is in short supply in the Coastal Plain and Mississippi embayment, Colorado Plateau and Wyoming Basin, glaciated Midwest, High Plains, and the non-glaciated Northern Plains. A variety of techniques have been used to overcome local shortages, such as the use of substitute materials, recycling, and importing high-quality aggregates from more distant locations.

Study of mechanical properties and recommendations for the application of waste Bakelite aggregate concrete

OpenAIRE

Nopagon Usahanunth; Seree Tuprakay; Waranon Kongsong; Sirawan Ruangchuay Tuprakay

2018-01-01

Bakelite waste from industrial manufacturing may be a hazard to the environment and public health. The utilization of waste Bakelite (WB) to replace natural aggregates (NA), such as natural coarse aggregate (NCA) and natural fine aggregate (NFA), in concrete and mortar is an approach for reducing both waste plastic and natural material. This research examines the utilization of waste Bakelite aggregate (WBA) in concrete and mortar mixtures to form waste Bakelite aggregate concrete (WBAC) and ...

Rydberg aggregates

Science.gov (United States)

Wüster, S.; Rost, J.-M.

2018-02-01

We review Rydberg aggregates, assemblies of a few Rydberg atoms exhibiting energy transport through collective eigenstates, considering isolated atoms or assemblies embedded within clouds of cold ground-state atoms. We classify Rydberg aggregates, and provide an overview of their possible applications as quantum simulators for phenomena from chemical or biological physics. Our main focus is on flexible Rydberg aggregates, in which atomic motion is an essential feature. In these, simultaneous control over Rydberg-Rydberg interactions, external trapping and electronic energies, allows Born-Oppenheimer surfaces for the motion of the entire aggregate to be tailored as desired. This is illustrated with theory proposals towards the demonstration of joint motion and excitation transport, conical intersections and non-adiabatic effects. Additional flexibility for quantum simulations is enabled by the use of dressed dipole-dipole interactions or the embedding of the aggregate in a cold gas or Bose-Einstein condensate environment. Finally we provide some guidance regarding the parameter regimes that are most suitable for the realization of either static or flexible Rydberg aggregates based on Li or Rb atoms. The current status of experimental progress towards enabling Rydberg aggregates is also reviewed.

Lightweight concrete with Algerian limestone dust. Part II: study on 50% and 100% replacement to normal aggregate at timely age

Directory of Open Access Journals (Sweden)

S. Kitouni

2015-12-01

Full Text Available Abstract A control lightweight concrete (LWC mixture made with 50% and 100% of limestone as a replacement of coarse aggregates in weight was prepared. Limestone is used for economical and environmental concern. The concrete samples were cured at 65% relative humidity at 20 ºC. The compressive and flexural tensile strengths, elastic modulus and Poisson's ratio of hardened concrete were measured. Laboratory compressive and tensile strength tests results showed that LWC can be produced by the use of limestone. The aim of this study is twofold: one is to design a lightweight concrete with the use of limestone that will provide an advantage of reduction in dead weight of a structure; and second is to obtain a more economical LWC mixture with the use of limestone.

Fine natural aggregate replacement for sandy residue from itabirite exploitation in Portland cement mortar

International Nuclear Information System (INIS)

Melo, V.A.R.; Freire, C.B.; Pereira Junior, S.S.; Lameiras, F.S.; Tello, C.C.O.

2011-01-01

The fine natural aggregates are a material largely used by the civil construction for mortar and concrete production. Due to tightening legal restrictions imposed on their extraction, alternative materials are being considered. The use of sandy residue from BIF (banded iron formations) exploitation was investigated. It requires their grinding and flotation to concentrate iron oxides. Large amounts of sandy residue composed of quartz and iron oxides are generated in this process. The sandy residue was characterized relative to mineralogical composition, particle size distribution, presence of organic impurities, and particle shape. Mortar formulations were prepared by varying the type of cement, the cement to aggregate proportion and the water/cement ratio (a/c). The results of viscosity and density of fresh mortar, setting time, and compressive strength are presented. Compressive strength up to 19.5 MPa at 28 days were achieved with the use of cement CPV, a/c ratio of 0.80 and cement:aggregate proportion of 1:2. The results demonstrate the technical feasibility of using sandy residue as fine aggregate. (author)

Sustainable Performance of Iraqi Asphalt Base Course Using Recycled Glass as Aggregate Replacement

Directory of Open Access Journals (Sweden)

Hamid Athab Eedan Al-Jameel

2018-03-01

Full Text Available Nowadays, a lot of waste glass produced through different sides of life. Applying sustainability has been widely used in different construction materials and flexible pavement was contained different recycled materials through different studies. Recycled glass, where it is nonmetallic and inorganic, it can neither be incinerated nor decomposed, so it may be difficult to reclaim, has been used as filler, fine and coarse aggregates in the asphalt base course. In this study, various standard asphalt tests, such as stability, flow, density and air voids, have been conducted on reference mix asphalt and mix asphalt with different percentages of recycled glass when it has been used as filler, fine and coarse aggregates in the base course. Generally, the results show good indication, especially when using 10% of the recycled glass instead of coarse aggregate with 40-50 asphalt grades. This percentage improves most characteristics such as strength retained index which indicates better performance than reference mix.  

Properties of concrete blocks prepared with low grade recycled aggregates.

Science.gov (United States)

Poon, Chi-Sun; Kou, Shi-cong; Wan, Hui-wen; Etxeberria, Miren

2009-08-01

Low grade recycled aggregates obtained from a construction waste sorting facility were tested to assess the feasibility of using these in the production of concrete blocks. The characteristics of the sorted construction waste are significantly different from that of crushed concrete rubbles that are mostly derived from demolition waste streams. This is due to the presence of higher percentages of non-concrete components (e.g. >10% soil, brick, tiles etc.) in the sorted construction waste. In the study reported in this paper, three series of concrete block mixtures were prepared by using the low grade recycled aggregates to replace (i) natural coarse granite (10mm), and (ii) 0, 25, 50, 75 and 100% replacement levels of crushed stone fine (crushed natural granite concrete blocks. Test results on properties such as density, compressive strength, transverse strength and drying shrinkage as well as strength reduction after exposure to 800 degrees C are presented below. The results show that the soil content in the recycled fine aggregate was an important factor in affecting the properties of the blocks produced and the mechanical strength deceased with increasing low grade recycled fine aggregate content. But the higher soil content in the recycled aggregates reduced the reduction of compressive strength of the blocks after exposure to high temperature due probably to the formation of a new crystalline phase. The results show that the low grade recycled aggregates obtained from the construction waste sorting facility has potential to be used as aggregates for making non-structural pre-cast concrete blocks.

Application of orthogonal test method in mix proportion design of recycled lightweight aggregate concrete

Science.gov (United States)

Zhao, Zhanshan; An, Le; Zhang, Yijing; Yuan, Jie

2017-03-01

Recycled lightweight aggregate concrete was made with construction waste and ceramsite brick mainly including brick. Using the orthogonal test method, the mix proportion of recycled lightweight aggregate concrete was studied, and the Influence regularity and significance of water binder ratio, fly ash, sand ratio, the amount of recycled aggregate proportion on the compressive strength of concrete, the strong influence of mass ratio, slump expansion degree was studied. Through the mean and range analysis of the test results, the results show that the water binder ratio has the greatest influence on the 28d intensity of recycled lightweight aggregate concrete. Secondly, the fly ash content, the recycled aggregate replacement rate and the sand ratio have little influence. For the factors of expansion: the proportion of fly ash = water binder ratio sand >sand rate> recycled aggregate replacement rate. When the content of fly ash is about 30%, the expanded degree of recycled lightweight aggregate concrete is the highest, and the workability of that is better and the strength of concrete with 28d and 56d are the highest. When the content of brickbat is about 40% brick particles, the strength of concrete reaches the highest.

Face-specific Replacement of Calcite by Amorphous Silica Nanoparticles

Science.gov (United States)

Liesegang, M.; Milke, R.; Neusser, G.; Mizaikoff, B.

2016-12-01

Amorphous silica, composed of nanoscale spheres, is an important biomineral, alteration product of silicate rocks on the Earth's surface, and precursor material for stable silicate minerals. Despite constant progress in silica sphere synthesis, fundamental knowledge of natural silica particle interaction and ordering processes leading to colloidal crystals is absent so far. To understand the formation pathways of silica spheres in a geologic environment, we investigated silicified Cretaceous mollusk shell pseudomorphs from Coober Pedy (South Australia) using focused ion beam (FIB)-SEM tomography, petrographic microscopy, µ-XRD, and EMPA. The shells consist of replaced calcite crystals (ionic strength remain constant throughout the replacement process, permitting continuous silica nanoparticle formation and diffusion-limited colloid aggregation. Our study provides a natural example of the transformation of an atomic crystal to an amorphous, mesoscale ordered material; thus, links the research fields of natural colloidal crystal formation, carbonate-silica replacement, and crystallization by oriented particle aggregation (CPA).

Transient and steady state creep response of ice I and magnesium sulfate hydrate eutectic aggregates

Science.gov (United States)

McCarthy, C.; Cooper, R.F.; Goldsby, D.L.; Durham, W.B.; Kirby, S.H.

2011-01-01

Using uniaxial compression creep experiments, we characterized the transient and steady state deformation behaviors of eutectic aggregates of system ice I and MgSO4 11H2O (MS11; meridianiite), which has significance because of its likely presence on moons of the outer solar system. Synthetic samples of eutectic liquid bulk composition, which produce eutectic colonies containing 0.35-0.50 volume fraction MS11, were tested as functions of colony size and lamellar spacing, temperature (230-250 K), and confining pressure (0.1 and 50 MPa) to strains ???0.2. Up to a differential stress of 6 MPa, the ice I-MS11 aggregates display an order of magnitude higher effective viscosity and higher stress sensitivity than do aggregates of pure polycrystalline ice at the same conditions. The creep data and associated microstructural observations demonstrate, however, that the aggregates are additionally more brittle than pure ice, approaching rate-independent plasticity that includes rupture of the hydrate phase at 6-8 MPa, depending on the scale of the microstructure. Microstructures of deformed samples reveal forms of semibrittle flow in which the hydrate phase fractures while the ice phase deforms plastically. Semibrittle flow in the icy shell of a planetary body would truncate the lithospheric strength envelope and thereby decrease the depth to the brittle-ductile transition by 55% and reduce the failure limit for compressional surface features from 10 to ???6 MPa. A constitutive equation that includes eutectic colony boundary sliding and intracolony flow is used to describe the steady state rheology of the eutectic aggregates. Copyright ?? 2011 by the American Geophysical Union.

Development of construction materials using nano-silica and aggregates recycled from construction and demolition waste.

Science.gov (United States)

Mukharjee, Bibhuti Bhusan; Barai, Sudhirkumar V

2015-06-01

The present work addresses the development of novel construction materials utilising commercial grade nano-silica and recycled aggregates retrieved from construction and demolition waste. For this, experimental work has been carried out to examine the influence of nano-silica and recycled aggregates on compressive strength, modulus of elasticity, water absorption, density and volume of voids of concrete. Fully natural and recycled aggregate concrete mixes are designed by replacing cement with three levels (0.75%, 1.5% and 3%) of nano-silica. The results of the present investigation depict that improvement in early days compressive strength is achieved with the incorporation of nano-silica in addition to the restoration of reduction in compressive strength of recycled aggregate concrete mixes caused owing to the replacement of natural aggregates by recycled aggregates. Moreover, the increase in water absorption and volume of voids with a reduction of bulk density was detected with the incorporation of recycled aggregates in place of natural aggregates. However, enhancement in density and reduction in water absorption and volume of voids of recycled aggregate concrete resulted from the addition of nano-silica. In addition, the results of the study reveal that nano-silica has no significant effect on elastic modulus of concrete. © The Author(s) 2015.

Durability and Shrinkage Characteristics of Self-Compacting Concretes Containing Recycled Coarse and/or Fine Aggregates

Directory of Open Access Journals (Sweden)

Mehmet Gesoglu

2015-01-01

Full Text Available This paper addresses durability and shrinkage performance of the self-compacting concretes (SCCs in which natural coarse aggregate (NCA and/or natural fine aggregate (NFA were replaced by recycled coarse aggregate (RCA and/or recycled fine aggregate (RFA, respectively. A total of 16 SCCs were produced and classified into four series, each of which included four mixes designed with two water to binder (w/b ratios of 0.3 and 0.43 and two silica fume replacement levels of 0 and 10%. Durability properties of SCCs were tested for rapid chloride penetration, water sorptivity, gas permeability, and water permeability at 56 days. Also, drying shrinkage accompanied by the water loss and restrained shrinkage of SCCs were monitored over 56 days of drying period. Test results revealed that incorporating recycled coarse and/or fine aggregates aggravated the durability properties of SCCs tested in this study. The drying shrinkage and restrained shrinkage cracking of recycled aggregate (RA concretes had significantly poorer performance than natural aggregate (NA concretes. The time of cracking greatly prolonged as the RAs were used along with the increase in water/binder ratio.

Effect of Partial Replacement of Sand With Quarry Dust on the ...

African Journals Online (AJOL)

This work investigated the effect of partial replacement of sand with quarry dust on the compressive strength, flexural strength, split tensile strength and water absorption of sandcrete blocks. River sand was replaced with quarry dust at percentages ranging from 0 to 40 at cement/combined aggregate ratio of 1: 6. The blocks ...

Corrosion Behavior of Steel Reinforcement in Concrete with Recycled Aggregates, Fly Ash and Spent Cracking Catalyst.

Science.gov (United States)

Gurdián, Hebé; García-Alcocel, Eva; Baeza-Brotons, Francisco; Garcés, Pedro; Zornoza, Emilio

2014-04-21

The main strategy to reduce the environmental impact of the concrete industry is to reuse the waste materials. This research has considered the combination of cement replacement by industrial by-products, and natural coarse aggregate substitution by recycled aggregate. The aim is to evaluate the behavior of concretes with a reduced impact on the environment by replacing a 50% of cement by industrial by-products (15% of spent fluid catalytic cracking catalyst and 35% of fly ash) and a 100% of natural coarse aggregate by recycled aggregate. The concretes prepared according to these considerations have been tested in terms of mechanical strengths and the protection offered against steel reinforcement corrosion under carbonation attack and chloride-contaminated environments. The proposed concrete combinations reduced the mechanical performance of concretes in terms of elastic modulus, compressive strength, and flexural strength. In addition, an increase in open porosity due to the presence of recycled aggregate was observed, which is coherent with the changes observed in mechanical tests. Regarding corrosion tests, no significant differences were observed in the case of the resistance of these types of concretes under a natural chloride attack. In the case of carbonation attack, although all concretes did not stand the highly aggressive conditions, those concretes with cement replacement behaved worse than Portland cement concretes.

An Investigation into the Use of Manufactured Sand as a 100% Replacement for Fine Aggregate in Concrete

Directory of Open Access Journals (Sweden)

Martins Pilegis

2016-06-01

Full Text Available Manufactured sand differs from natural sea and river dredged sand in its physical and mineralogical properties. These can be both beneficial and detrimental to the fresh and hardened properties of concrete. This paper presents the results of a laboratory study in which manufactured sand produced in an industry sized crushing plant was characterised with respect to its physical and mineralogical properties. The influence of these characteristics on concrete workability and strength, when manufactured sand completely replaced natural sand in concrete, was investigated and modelled using artificial neural networks (ANN. The results show that the manufactured sand concrete made in this study generally requires a higher water/cement (w/c ratio for workability equal to that of natural sand concrete due to the higher angularity of the manufactured sand particles. Water reducing admixtures can be used to compensate for this if the manufactured sand does not contain clay particles. At the same w/c ratio, the compressive and flexural strength of manufactured sand concrete exceeds that of natural sand concrete. ANN proved a valuable and reliable method of predicting concrete strength and workability based on the properties of the fine aggregate (FA and the concrete mix composition.

An Investigation into the Use of Manufactured Sand as a 100% Replacement for Fine Aggregate in Concrete.

Science.gov (United States)

Pilegis, Martins; Gardner, Diane; Lark, Robert

2016-06-02

Manufactured sand differs from natural sea and river dredged sand in its physical and mineralogical properties. These can be both beneficial and detrimental to the fresh and hardened properties of concrete. This paper presents the results of a laboratory study in which manufactured sand produced in an industry sized crushing plant was characterised with respect to its physical and mineralogical properties. The influence of these characteristics on concrete workability and strength, when manufactured sand completely replaced natural sand in concrete, was investigated and modelled using artificial neural networks (ANN). The results show that the manufactured sand concrete made in this study generally requires a higher water/cement (w/c) ratio for workability equal to that of natural sand concrete due to the higher angularity of the manufactured sand particles. Water reducing admixtures can be used to compensate for this if the manufactured sand does not contain clay particles. At the same w/c ratio, the compressive and flexural strength of manufactured sand concrete exceeds that of natural sand concrete. ANN proved a valuable and reliable method of predicting concrete strength and workability based on the properties of the fine aggregate (FA) and the concrete mix composition.

Environmental performance and mechanical analysis of concrete containing recycled asphalt pavement (RAP) and waste precast concrete as aggregate.

Science.gov (United States)

Erdem, Savaş; Blankson, Marva Angela

2014-01-15

The overall objective of this research project was to investigate the feasibility of incorporating 100% recycled aggregates, either waste precast concrete or waste asphalt planning, as replacements for virgin aggregates in structural concrete and to determine the mechanical and environmental performance of concrete containing these aggregates. Four different types of concrete mixtures were designed with the same total water cement ratio (w/c=0.74) either by using natural aggregate as reference or by totally replacing the natural aggregate with recycled material. Ground granulated blast furnace slag (GGBS) was used as a mineral addition (35%) in all mixtures. The test results showed that it is possible to obtain satisfactory performance for strength characteristics of concrete containing recycled aggregates, if these aggregates are sourced from old precast concrete. However, from the perspective of the mechanical properties, the test results indicated that concrete with RAP aggregate cannot be used for structural applications. In terms of leaching, the results also showed that the environmental behaviour of the recycled aggregate concrete is similar to that of the natural aggregate concrete. Copyright © 2013 Elsevier B.V. All rights reserved.

Evaluation of the environmental, material, and structural performance of recycled aggregate concrete

Science.gov (United States)

Michaud, Katherine Sarah

Concrete is the most commonly used building material in the construction industry, and contributes to 52% of construction and demolition waste in Canada. Recycled concrete aggregate (RCA) is one way to reduce this impact. To evaluate the performance of coarse and granular (fine and coarse) RCA in structural concrete applications, four studies were performed: an environmental assessment, a material testing program, a shear performance study, and a flexural performance study. To determine the environmental benefits of recycled aggregate concrete (RAC), three case studies were investigated using different populations and proximities to city centres. Environmental modelling suggested that RCA replacement could result in energy savings and greenhouse gas emission reductions, especially in remote areas. Tests were performed to determine if the volumetric replacement of up to 30% coarse RCA and 20% granular RCA is suitable for structural concrete applications in Canada. Fresh, hardened, and durability properties were evaluated. All five (5) of the RCA mixes showed equivalent material performance to the control mixes and met the requirements for a structural concrete mix. The five (5) RAC mixes were also used in structural testing. One-way reinforced concrete slab specimens were tested to failure to evaluate the shear and flexural performance of the RAC members. Peak capacities of and crack formation within each member were analyzed to evaluate the performance of RAC compared to conventional concrete. The shear capacity of specimens made from four (4) of the five (5) RAC mixtures was higher or equivalent to the control specimens. Specimens of the concrete mixture containing the highest content of recycled aggregate, 20% volumetric replacement of granular RCA, had shear capacities 14.1% lower, and exhibited cracking at lower loads than the control. The average flexural capacities of all RAC specimens were within 3.7% of the control specimens. Results from this research

Leaching assessment of concrete made of recycled coarse aggregate: physical and environmental characterisation of aggregates and hardened concrete.

Science.gov (United States)

Galvín, A P; Agrela, F; Ayuso, J; Beltrán, M G; Barbudo, A

2014-09-01

Each year, millions of tonnes of waste are generated worldwide, partially through the construction and demolition of buildings. Recycling the resulting waste could reduce the amount of materials that need to be manufactured. Accordingly, the present work has analysed the potential reuse of construction waste in concrete manufacturing by replacing the natural aggregate with recycled concrete coarse aggregate. However, incorporating alternative materials in concrete manufacturing may increase the pollutant potential of the product, presenting an environmental risk via ground water contamination. The present work has tested two types of concrete batches that were manufactured with different replacement percentages. The experimental procedure analyses not only the effect of the portion of recycled aggregate on the physical properties of concrete but also on the leaching behaviour as indicative of the contamination degree. Thus, parameters such as slump, density, porosity and absorption of hardened concrete, were studied. Leaching behaviour was evaluated based on the availability test performed to three aggregates (raw materials of the concrete batches) and on the diffusion test performed to all concrete. From an environmental point of view, the question of whether the cumulative amount of heavy metals that are released by diffusion reaches the availability threshold was answered. The analysis of concentration levels allowed the establishment of different groups of metals according to the observed behaviour, the analysis of the role of pH and the identification of the main release mechanisms. Finally, through a statistical analysis, physical parameters and diffusion data were interrelated. It allowed estimating the relevance of porosity, density and absorption of hardened concrete on diffusion release of the metals in study. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mechanical and radiation shielding properties of mortars with additive fine aggregate mine waste

International Nuclear Information System (INIS)

Gallala, Wissem; Hayouni, Yousra; Gaied, Mohamed Essghaier; Fusco, Michael; Alsaied, Jasmin; Bailey, Kathryn; Bourham, Mohamed

2017-01-01

Highlights: • Effectiveness of mine waste as additive fine aggregate has been investigated. • Experimental results are verified by computationally from composition of synthesized samples. • Work focuses on shielding materials for nuclear systems including spent fuel storage and drycasks. - Abstract: Incorporation of barite-fluorspar mine waste (BFMW) as a fine aggregate additive has been investigated for its effect on the mechanical and shielding properties of cement mortar. Several mortar mixtures were prepared with different proportions of BFMW ranging from 0% to 30% as fine aggregate replacement. Cement mortar mixtures were evaluated for density, compressive and tensile strengths, and gamma ray radiation shielding. The results revealed that the mortar mixes containing 25% BFMW reaches the highest compressive strength values, which exceeded 50 MPa. Evaluation of gamma-ray attenuation was both measured by experimental tests and computationally calculated using MicroShield software package, and results have shown that using BFMW aggregates increases attenuation coefficient by about 20%. These findings have demonstrated that the mine waste can be suitably used as partial replacement aggregate to improve radiation shielding as well as to reduce the mortar and concrete costs.

Recycled aggregates concrete: aggregate and mix properties

Directory of Open Access Journals (Sweden)

González-Fonteboa, B.

2005-09-01

Full Text Available This study of structural concrete made with recycled concrete aggregate focuses on two issues: 1. The characterization of such aggregate on the Spanish market. This involved conducting standard tests to determine density, water absorption, grading, shape, flakiness and hardness. The results obtained show that, despite the considerable differences with respect to density and water absorption between these and natural aggregates, on the whole recycled aggregate is apt for use in concrete production. 2. Testing to determine the values of basic concrete properties: mix design parameters were established for structural concrete in non-aggressive environments. These parameters were used to produce conventional concrete, and then adjusted to manufacture recycled concrete aggregate (RCA concrete, in which 50% of the coarse aggregate was replaced by the recycled material. Tests were conducted to determine the physical (density of the fresh and hardened material, water absorption and mechanical (compressive strength, splitting tensile strength and modulus of elasticity properties. The results showed that, from the standpoint of its physical and mechanical properties, concrete in which RCA accounted for 50% of the coarse aggregate compared favourably to conventional concrete.

Se aborda el estudio de hormigones estructurales fabricados con áridos reciclados procedentes de hormigón, incidiéndose en dos aspectos: 1. Caracterización de tales áridos, procedentes del mercado español. Para ello se llevan a cabo ensayos de densidad, absorción, granulometría, coeficiente de forma, índice de lajas y dureza. Los resultados obtenidos han puesto de manifiesto que, a pesar de que existen diferencias notables (sobre todo en cuanto a densidad y absorción con los áridos naturales, las características de los áridos hacen posible la fabricación de hormigones. 2. Ensayos sobre propiedades básicas de los hormigones: se establecen parámetros de dosificaci

Tillage practices in the conterminous United States, 1989-2004-Datasets Aggregated by Watershed

Science.gov (United States)

Baker, Nancy T.

2011-01-01

This report documents the methods used to aggregate county-level tillage practices to the 8-digit hydrologic unit (HU) watershed. The original county-level data were collected by the Conservation Technology Information Center (CTIC). The CTIC collects tillage data by conducting surveys about tillage systems for all counties in the United States. Tillage systems include three types of conservation tillage (no-till, ridge-till, and mulch-till), reduced tillage, and intensive tillage. Total planted acreage for each tillage practice for each crop grown is reported to the CTIC. The dataset includes total planted acreage by tillage type for selected crops (corn, cotton, grain sorghum, soybeans, fallow, forage, newly established permanent pasture, spring and fall seeded small grains, and 'other' crops) for 1989-2004. Two tabular datasets, based on the 1992 enhanced and 2001 National Land Cover Data (NLCD), are provided as part of this report and include the land-cover area-weighted interpolation and aggregation of acreage for each tillage practice in each 8-digit HU watershed in the conterminous United States for each crop. Watershed aggregations were done by overlying the 8-digit HU polygons with a raster of county boundaries and a raster of either the enhanced 1992 or the 2001 NLCD for cultivated land to derive a county/land-cover area weighting factor. The weighting factor then was applied to the county-level tillage data for the counties within each 8-digit HU and summed to yield the total acreage of each tillage type within each 8-digit HU watershed.

Understanding curcumin-induced modulation of protein aggregation.

Science.gov (United States)

Ahmad, Basir; Borana, Mohanish S; Chaudhary, Ankur P

2017-07-01

Curcumin, a diarylheptanoid compound, found in spice turmeric is known to alter the aggregation of proteins and reduce the toxicity of the aggregates. This review looks at the molecular basis of modulating protein aggregation and toxicity of the aggregates. Foremost, we identify the interaction of curcumin and its derivatives with proteins/peptides and the effect of their interaction on the conformational stability and unfolding/folding pathway(s). The unfolding/folding processes generate partially folded/unfolded intermediate, which serve as aggregation precursor state. Secondly, we discuss the effect of curcumin binding on the kinetics parameters of the aggregation process, which give information about the mechanism of the aggregation inhibition. We describe, in addition, that curcumin can accelerate/promote fibril formation by binding to oligomeric intermediate(s) accumulated in the aggregation pathway. Finally, we discuss the correlation of curcumin-induced monomeric and/or oligomeric precursor states with aggregate structure and toxicity. On the basis of these discussions, we propose a model describing curcumin-induced inhibition/promotion of formation of amyloid-like fibrils. Copyright © 2016 Elsevier B.V. All rights reserved.

Properties of concrete containing foamed concrete block waste as fine aggregate replacement

Science.gov (United States)

Muthusamy, K.; Budiea, A. M. A.; Zaidan, A. L. F.; Rasid, M. H.; Hazimmah, D. S.

2017-11-01

Environmental degradation due to excessive sand mining dumping at certain places and disposal of foamed concrete block waste from lightweight concrete producing industry are issues that should be resolved for a better and cleaner environment of the community. Thus, the main intention of this study is to investigate the potential of foamed concrete block waste as partial sand replacement in concrete production. The foamed concrete waste (FCW) used in this research that were supplied by a local lightweight concrete producing industry. The workability and compressive strength of concrete containing various percentage of foamed concrete waste as partial sand replacement has been investigated. Prior to the use, the foamed concrete waste were crushed to produce finer particles. Six concrete mixes containing various content of crushed foamed concrete waste that are 0%, 10%, 20%, 30%, 40% and 50% were used in this experimental work. Then the prepared specimens were placed in water curing until the testing age. Compressive strength test and flexural strength tests were conducted at 7, 14 and 28 days. The result shows that integration of crushed foamed concrete waste as partial sand replacement in concrete reduces the mix workability. It is interesting to note that both compressive strength and flexural strength of concrete improves when 30% crushed foamed concrete waste is added as partial sand replacement.

Influence of bagasse ash and recycled concrete aggregate on hardened properties of high-strength concrete

Directory of Open Access Journals (Sweden)

P. Rattanachu

2018-04-01

Full Text Available This research aimed to use of bagasse ash as a cement replacement in high-strength recycled aggregate concrete (HS-RAC. Crushed limestone was replaced with 100% recycled concrete aggregate (RCA and the ground bagasse ash (GBA was used to partially replace ordinary Portland cement (OPC at 20, 35 and 50%wt of binder to cast HS-RAC. The results indicated that the replacing of crushed limestone with RCA had a negative impact on the properties of the concrete. Increasing the amount of GBA in HS-RAC resulted in a decrease in density and an increase in the volume of permeable pore space. The concrete mixtures prepared with 20%wt GBA replacement of OPC promoted greater the compressive strength than the conventional concrete (CT concrete at 90 days or more. HS-RAC with GBA (up to 50% was more durable in terms of chloride ion penetration resistance, although it had lower compressive strength than the CT concrete.

Innovative Solid State Lighting Replacements for Industrial and Test Facility Locations, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The proposed effort will develop a solid-state LED replacement lamp for rocket engine test stand lighting and more general hazardous-location lighting. The LED...

Aggregate-level analysis and prediction of midterm senatorial elections in the United States, 1974-1986.

Science.gov (United States)

Lichtman, A J; Keilis-Borok, V I

1989-12-01

Pattern recognition study demonstrates that the outcomes of American midterm senatorial elections follow the dynamics of simple integral parameters that depict preelectoral situations aggregated to the state as a whole. A set of "commonsense" parameters is identified that is sufficient to predict such elections state-by-state and year-by-year. The analysis rejects many similar commonsense parameters. The existence and nature of integral collective behavior in U.S. elections at the level of the individual states is investigated. Implications for understanding the American electoral process are discussed.

Corrosion Behavior of Steel Reinforcement in Concrete with Recycled Aggregates, Fly Ash and Spent Cracking Catalyst

Directory of Open Access Journals (Sweden)

Hebé Gurdián

2014-04-01

Full Text Available The main strategy to reduce the environmental impact of the concrete industry is to reuse the waste materials. This research has considered the combination of cement replacement by industrial by-products, and natural coarse aggregate substitution by recycled aggregate. The aim is to evaluate the behavior of concretes with a reduced impact on the environment by replacing a 50% of cement by industrial by-products (15% of spent fluid catalytic cracking catalyst and 35% of fly ash and a 100% of natural coarse aggregate by recycled aggregate. The concretes prepared according to these considerations have been tested in terms of mechanical strengths and the protection offered against steel reinforcement corrosion under carbonation attack and chloride-contaminated environments. The proposed concrete combinations reduced the mechanical performance of concretes in terms of elastic modulus, compressive strength, and flexural strength. In addition, an increase in open porosity due to the presence of recycled aggregate was observed, which is coherent with the changes observed in mechanical tests. Regarding corrosion tests, no significant differences were observed in the case of the resistance of these types of concretes under a natural chloride attack. In the case of carbonation attack, although all concretes did not stand the highly aggressive conditions, those concretes with cement replacement behaved worse than Portland cement concretes.

Cyclic Behavior of Low Rise Concrete Shear Walls Containing Recycled Coarse and Fine Aggregates.

Science.gov (United States)

Qiao, Qiyun; Cao, Wanlin; Qian, Zhiwei; Li, Xiangyu; Zhang, Wenwen; Liu, Wenchao

2017-12-07

In this study, the cyclic behaviors of low rise concrete shear walls using recycled coarse or fine aggregates were investigated. Eight low rise Recycled Aggregates Concrete (RAC) shear wall specimens were designed and tested under a cyclic loading. The following parameters were varied: replacement percentages of recycled coarse or fine aggregates, reinforcement ratio, axial force ratio and X-shaped rebars brace. The failure characteristics, hysteretic behavior, strength and deformation capacity, strain characteristics and stiffness were studied. Test results showed that the using of the Recycled Coarse Aggregates (RCA) and its replacement ratio had almost no influence on the mechanical behavior of the shear wall; however, the using of Recycled Fine Aggregates (RFA) had a certain influence on the ductility of the shear wall. When the reinforcement ratio increased, the strength and ductility also increased. By increasing the axial force ratio, the strength increased but the ductility decreased significantly. The encased brace had a significant effect on enhancing the RAC shear walls. The experimental maximum strengths were evaluated with existing design codes, it was indicated that the strength evaluation of the low rise RAC shear walls can follow the existing design codes of the conventional concrete shear walls.

Synthetic aggregates from combustion ashes using an innovative rotary kiln.

Science.gov (United States)

Wainwright, P J; Cresswell, D J

2001-01-01

This paper describes the use of a number of different combustion ashes to manufacture synthetic aggregates using an innovative rotary 'Trefoil' kiln. Three types of combustion ash were used, namely: incinerated sewage sludge ash (ISSA); municipal solid waste incinerator bottom ash (MSWIBA-- referred to here as BA); and pulverised fuel ash (Pfa). The fine waste ash fractions listed above were combined with a binder to create a plastic mix that was capable of being formed into 'green pellets'. These pellets were then fired in a Trefoil kiln to sinter the ashes into hard fused aggregates that were then tested for use as a replacement for the natural coarse aggregate in concrete. Results up to 28 days showed that these synthetic aggregates were capable of producing concretes with compressive strengths ranging from 33 to 51 MPa, equivalent to between 73 and 112% of that of the control concrete made with natural aggregates.

On Aggregation Requirements for Harmonic Stability Analysis in Wind Power Plants

DEFF Research Database (Denmark)

Dowlatabadi, Mohammadkazem Bakhshizadeh; Hjerrild, Jesper; Kocewiak, Łukasz

2017-01-01

In harmonic stability studies, stable operation of a power system must be ensured at any possible configuration. This leads to a large number of cases due to the high number of components in a power system. An aggregated model can be used to lower the complexity and to reduce the number...... of different cases. In other words, several similar converters (e.g. Wind Turbine Generators) can be replaced by a converter with larger ratings. In most cases, aggregated models work well for stability studies, however, in some cases the aggregation might result in a wrong evaluation of stability...

An FTIR study on the chlorophyll and apoprotein aggregation states in LHCII due to solvent effects

CSIR Research Space (South Africa)

Smit, Jacoba E

2012-07-01

Full Text Available Photosynthesis provides us with the most abundant and efficient light-harvesting systems found in nature. The photosynthetic process is very much dependent on the aggregation state of the chlorophylls and secondary conformational structure...

Replacing HDDs with Solid-State Flash Disks in PXIbus-Based Systems

International Nuclear Information System (INIS)

Zhao, Z W; Zeng, L

2006-01-01

New security features, constantly decreasing prices, solid-state Flash disks are becoming a popular alternative for replacing failure-prone mechanical Hard Disk Drives (HDDs) in PXIbus-based military systems. The key component in high-capacity solid-state Flash disks is NAND Flash, but with a specification that shows only 100,000-300,000 write/erase cycles, engineers may be concerned that the lifetime of Flash disks cannot meet their application requirements. With the right Flash management, Flash disks are able to provide the reliability and endurance that military applications need

Waste tyre rubberized concrete: properties at fresh and hardened state.

Science.gov (United States)

Aiello, M A; Leuzzi, F

2010-01-01

The main objective of this paper is to investigate the properties of various concrete mixtures at fresh and hardened state, obtained by a partial substitution of coarse and fine aggregate with different volume percentages of waste tyres rubber particles, having the same dimensions of the replaced aggregate. Workability, unit weight, compressive and flexural strength and post-cracking behaviour were evaluated and a comparison of the results for the different rubcrete mixtures were proposed in order to define the better mix proportions in terms of mechanical properties of the rubberized concrete. Results showed in this paper were also compared to data reported in literature. Moreover, a preliminary geometrical, physical and mechanical characterization on scrap tyre rubber shreds was made. The rubberized concrete mixtures showed lower unit weight compared to plain concrete and good workability. The results of compressive and flexural tests indicated a larger reduction of mechanical properties of rubcrete when replacing coarse aggregate rather than fine aggregate. On the other hand, the post-cracking behaviour of rubberized concrete was positively affected by the substitution of coarse aggregate with rubber shreds, showing a good energy absorption and ductility indexes in the range observed for fibrous concrete, as suggested by standard (ASTM C1018-97, 1997). 2010 Elsevier Ltd. All rights reserved.

Study of the behavior of aggregate of calcined clay for use in permeable pavements for the city of Manaus

International Nuclear Information System (INIS)

Oliveira, M.S.; Vilela, P.A.T.; Araujo, V.S.

2016-01-01

Research on the production of ceramic aggregates and their use in paving in the country began in the 80’s in the search for an alternative material that could replace the pebble or crushed stone, studied the clay, considered an abundant mineral resource by virtue of being the predominant soil in this region and which were made synthetic calcinated clay aggregates (ASAC), for their application in permeable paving concrete motivated by the lack of permeable areas. The study consists of the characterization of materials for manufacture of concrete slabs permeable and the assessment of the effects of synthetic aggregate on its properties in fresh and hardened state. The ceramic bodies were subjected to tests of X-ray diffraction, determination of chemical composition and plasticity. The results indicate that the use of synthetic clusters is a viable alternative for the production of porous concrete. (author)

Reusing recycled aggregates in structural concrete

Science.gov (United States)

Kou, Shicong

The utilization of recycled aggregates in concrete can minimize environmental impact and reduce the consumption of natural resources in concrete applications. The aim of this thesis is to provide a scientific basis for the possible use of recycled aggregates in structure concrete by conducting a comprehensive programme of laboratory study to gain a better understanding of the mechanical, microstructure and durability properties of concrete produced with recycled aggregates. The study also explored possible techniques to of improve the properties of recycled aggregate concrete that is produced with high percentages (≧ 50%) of recycled aggregates. These techniques included: (a) using lower water-to-cement ratios in the concrete mix design; (b) using fly ash as a cement replacement or as an additional mineral admixture in the concrete mixes, and (c) precasting recycled aggregate concrete with steam curing regimes. The characteristics of the recycled aggregates produced both from laboratory and a commercially operated pilot construction and demolition (C&D) waste recycling plant were first studied. A mix proportioning procedure was then established to produce six series of concrete mixtures using different percentages of recycled coarse aggregates with and without the use of fly ash. The water-to-cement (binder) ratios of 0.55, 0.50, 0.45 and 0.40 were used. The fresh properties (including slump and bleeding) of recycled aggregate concrete (RAC) were then quantified. The effects of fly ash on the fresh and hardened properties of RAC were then studied and compared with those RAC prepared with no fly ash addition. Furthermore, the effects of steam curing on the hardened properties of RAC were investigated. For micro-structural properties, the interfacial transition zones of the aggregates and the mortar/cement paste were analyzed by SEM and EDX-mapping. Moreover, a detailed set of results on the fracture properties for RAC were obtained. Based on the experimental

Feasibility Assessment of the Use of Recycled Aggregates for Asphalt Mixtures

Directory of Open Access Journals (Sweden)

F. C. G. Martinho

2018-05-01

Full Text Available The use of recycled aggregates, manufactured from several by-products, to replace virgin aggregates in the production of pavement asphalt mixtures needs to be encouraged. Nevertheless, there are some concerns and uncertainties about the actual environmental, economic and mechanical performance resulting from the incorporation of recycled aggregates in asphalt mixtures. Therefore, this paper has the goal of discussing important features to help decision makers to select recycled aggregates as raw materials for asphalt mixtures. Based on the literature review carried out and the own previous experience of the authors, the article’s main findings reveal that incorporating some of the most common recycled aggregates into asphalt mixtures is feasible, even in a life-cycle analysis perspective. Although some specific technical operations are sometimes necessary when using recycled aggregates in asphalt mixtures, some benefits in terms of environmental impacts, energy use and costs are likely to be achieved, as well as in what concerns the mechanical performance of the asphalt mixtures.

Compressive and flexural strength of expanded perlite aggregate mortar subjected to high temperatures

Science.gov (United States)

Zulkifeli, Muhamad Faqrul Hisham bin Mohd; Saman@Hj Mohamed, Hamidah binti Mohd

2017-08-01

Work on thermal resistant of outer structures of buildings is one of the solution to reduce death, damages and properties loss in fire cases. Structures protected with thermal resistant materials can delay or avoid failure and collapse during fire. Hence, establishment of skin cladding with advance materials to protect the structure of buildings is a necessary action. Expanded perlite is a good insulation material which can be used as aggregate replacement in mortar. This study is to study on mortar mechanical properties of flexural and compressive strength subjected to elevated temperatures using expanded perlite aggregate (EPA). This study involved experimental work which was developing mortar with sand replacement by volume of 0%, 10%, 20%, 30% and 40% of EPA and cured for 56 days. The mortars then exposed to 200°C, 400 °C, 700 °C and 1000 °C. Flexural and compressive strength of the mortar were tested. The tests showed that there were increased of flexural and compressive strength at 200°C, and constantly decreased when subjected to 400°C, 700°C and 1000 °C. There were also variation of strengths at different percentages of EPA replacement. Highest compressive strength and flexural strength recorded were both at 200 °C with 65.52 MPa and 21.34 MPa respectively. The study conclude that by using EPA as aggregate replacement was ineffective below elevated temperatures but increased the performance of the mortar at elevated temperatures.

Flexural Behaviour Of Reinforced Concrete Beams Containing Expanded Glass As Lightweight Aggregates

Directory of Open Access Journals (Sweden)

Khatib Jamal

2015-12-01

Full Text Available The flexural properties of reinforced concrete beams containing expanded glass as a partial fine aggregate (sand replacement are investigated. Four concrete mixes were employed to conduct this study. The fine aggregate was replaced with 0%, 25%, 50% and 100% (by volume expanded glass. The results suggest that the incorporation of 50% expanded glass increased the workability of the concrete. The compressive strength was decreasing linearly with the increasing amount of expanded glass. The ductility of the concrete beam significantly improved with the incorporation of the expanded glass. However, the load-carrying capacity of the beam and load at which the first crack occurs was reduced. It was concluded that the inclusion of expanded glass in structural concrete applications is feasible.

A study of fine aggregate replacement with fly ash an environmental friendly and economical solution.

Science.gov (United States)

Pofale, A D; Deo, S V

2010-10-01

The use of fly ash as a replacement of sand has a great potential to benefit our society in terms of reducing demand of natural sand, reducing environmental problems, conserving energy and reducing landfill area requirement. This paper presents an approach to increase the utilization of fly ash and conserve scarcely available natural sand for sustainable development. The experimental investigation by the inclusion of fly ash as a partial replacement of sand as compared to control cement mortar mixes indicated 50% to 100% increase in the compressive strength of mortar at 91 days. Replacement of 50% sand with fly ash can save about 0.4 m3 sand. Comparison of cost per N/mm2 compressive strength has shown about 40% to 60% saving in cost. Based on the experimental results, correlations are developed for finding out the compressive strength and cost at 28 and 91 days. Sand was replaced with 10% to 50% of fly ash by weight and 0.5, 0.55, 0.6 and 0.65 W/C ratios were used. Flow test performed for mortar revealed that as the percentage replacement of sand with the fly ash increased the flow of the mortar decreased. It was also observed that wet and dry densities were more than the control mortar for 10% & 20% replacement of sand with fly ash but for higher replacement percentage density reduced marginally.

Trends in Aggregate Vehicle Emissions: Do We Need To Emissions Test?

OpenAIRE

Matthew Kahn

1995-01-01

Vehicle emissions are falling. As the oldest vehicles in the fleet are scrapped and are replaced by cleaner vehicles, aggregate emissions decline. Given this trend, must costly used car regulation continue? The Clean Air Act of 1990 requires more stringent used car testing without considering the counter-factual of how aggregate emissions would evolve in the absence of more regulation. This paper use data on vehicle scrappage rates, vehicle emissions by model year, and county air quality leve...

Impact of the economic downturn on total joint replacement demand in the United States: updated projections to 2021.

Science.gov (United States)

Kurtz, Steven M; Ong, Kevin L; Lau, Edmund; Bozic, Kevin J

2014-04-16

Few studies have explored the role of the National Health Expenditure and macroeconomics on the utilization of total joint replacement. The economic downturn has raised questions about the sustainability of growth for total joint replacement in the future. Previous projections of total joint replacement demand in the United States were based on data up to 2003 using a statistical methodology that neglected macroeconomic factors, such as the National Health Expenditure. Data from the Nationwide Inpatient Sample (1993 to 2010) were used with United States Census and National Health Expenditure data to quantify historical trends in total joint replacement rates, including the two economic downturns in the 2000s. Primary and revision hip and knee arthroplasty were identified using codes from the International Classification of Diseases, Ninth Revision, Clinical Modification. Projections in total joint replacement were estimated using a regression model incorporating the growth in population and rate of arthroplasties from 1993 to 2010 as a function of age, sex, race, and census region using the National Health Expenditure as the independent variable. The regression model was used in conjunction with government projections of National Health Expenditure from 2011 to 2021 to estimate future arthroplasty rates in subpopulations of the United States and to derive national estimates. The growth trend for the incidence of joint arthroplasty, for the overall United States population as well as for the United States workforce, was insensitive to economic downturns. From 2009 to 2010, the total number of procedures increased by 6.0% for primary total hip arthroplasty, 6.1% for primary total knee arthroplasty, 10.8% for revision total hip arthroplasty, and 13.5% for revision total knee arthroplasty. The National Health Expenditure model projections for primary hip replacement in 2020 were higher than a previously projected model, whereas the current model estimates for total

Aggregate formation in a freshwater bacterial strain induced by growth state and conspecific chemical cues

Czech Academy of Sciences Publication Activity Database

Blom, J. F.; Horňák, Karel; Šimek, Karel; Pernthaler, J.

2010-01-01

Roč. 12, č. 9 (2010), s. 2486-2495 ISSN 1462-2912 R&D Projects: GA ČR(CZ) GA206/08/0015 Institutional research plan: CEZ:AV0Z60170517 Keywords : aggregate formation * Sphingobium sp. * chemical cues * growth state Subject RIV: EE - Microbiology, Virology Impact factor: 5.537, year: 2010

Benefits of aggregates surface modification in concrete production

Science.gov (United States)

Junak, J.; Sicakova, A.

2017-10-01

In our study, recycled concrete aggregates (RCA), which surfaces had been modified by geopolymer material based on coal fly ash, were used to produce the concrete samples. In these samples, fraction 4/8 mm was replaced by recycled concrete aggregate with a range of 100%. To modify the surface of RCA was “Solo” and “Triple stage” modification used. On these samples real density, total water absorption and compressive strength were examined after 28, 90, 180 and 365 days of hardening. The highest compressive strength 56.8 MPa, after 365 days hardening, reached sample which had improved RCA surface by “Triple stage mixing”.

Cyclic Behavior of Low Rise Concrete Shear Walls Containing Recycled Coarse and Fine Aggregates

Directory of Open Access Journals (Sweden)

Qiyun Qiao

2017-12-01

Full Text Available In this study, the cyclic behaviors of low rise concrete shear walls using recycled coarse or fine aggregates were investigated. Eight low rise Recycled Aggregates Concrete (RAC shear wall specimens were designed and tested under a cyclic loading. The following parameters were varied: replacement percentages of recycled coarse or fine aggregates, reinforcement ratio, axial force ratio and X-shaped rebars brace. The failure characteristics, hysteretic behavior, strength and deformation capacity, strain characteristics and stiffness were studied. Test results showed that the using of the Recycled Coarse Aggregates (RCA and its replacement ratio had almost no influence on the mechanical behavior of the shear wall; however, the using of Recycled Fine Aggregates (RFA had a certain influence on the ductility of the shear wall. When the reinforcement ratio increased, the strength and ductility also increased. By increasing the axial force ratio, the strength increased but the ductility decreased significantly. The encased brace had a significant effect on enhancing the RAC shear walls. The experimental maximum strengths were evaluated with existing design codes, it was indicated that the strength evaluation of the low rise RAC shear walls can follow the existing design codes of the conventional concrete shear walls.

Optimization of Packing Density of M30 Concrete With Steel Slag As Coarse Aggregate Using Fuzzy Logic

Directory of Open Access Journals (Sweden)

Arivoli M.

2017-09-01

Full Text Available Concrete plays a vital role in the design and construction of the infrastructure. To meet the global demand of concrete in future, it is becoming a challenging task to find suitable alternatives to natural aggregates. Steel slag is a by-product of steel making process. The steel slag aggregates are characterized by studying particle size and shape, physical and chemical properties, and mechanical properties as per IS: 2386-1963. The characterization study reveals the better performance of steel slag aggregate over natural coarse aggregate. M30 grade of concrete is designed and natural coarse aggregate is completely replaced by steel slag aggregate. Packing density of aggregates affects the characteristics of concrete. The present paper proposes a fuzzy system for concrete mix proportioning which increases the packing density. The proposed fuzzy system have four sub fuzzy system to arrive compressive strength, water cement ratio, ideal grading curve and free water content for concrete mix proportioning. The results show, the concrete mix proportion of the given fuzzy model agrees with IS method. The comparison of results shows that both proposed fuzzy system and IS method, there is a remarkable increase in compressive strength and bulk density, with increment in the percentage replacement of steel slag.

Meal replacement: calming the hot-state brain network of appetite.

Science.gov (United States)

Paolini, Brielle M; Laurienti, Paul J; Norris, James; Rejeski, W Jack

2014-01-01

There is a growing awareness in the field of neuroscience that the self-regulation of eating behavior is driven by complex networks within the brain. These networks may be vulnerable to "hot states" which people can move into and out of dynamically throughout the course of a day as a function of changes in affect or visceral cues. The goal of the current study was to identify and determine differences in the Hot-state Brain Network of Appetite (HBN-A) that exists after a brief period of food restraint followed either by the consumption of a meal replacement (MR) or water. Fourteen overweight/obese adults came to our laboratory on two different occasions. Both times they consumed a controlled breakfast meal and then were restricted from eating for 2.5 h prior to an MRI scan. On one visit, they consumed a meal replacement (MR) liquid meal after this period of food restriction; on the other visit they consumed an equal amount of water. After these manipulations, the participants underwent a resting fMRI scan. Our first study aim employed an exploratory, data-driven approach to identify hubs relevant to the HBN-A. Using data from the water condition, five regions were found to be the hubs or nodes of the HBN-A: insula, anterior cingulated cortex, the superior temporal pole, the amygdala, and the hippocampus. We then demonstrated that the consumption of a liquid MR dampened interconnectivity between the nodes of the HBN-A as compared to water. Importantly and consistent with these network data, the consumption of a MR beverage also lowered state cravings and hunger.

Meal Replacement: Calming the Hot-State Brain Network of Appetite

Directory of Open Access Journals (Sweden)

Brielle ePaolini

2014-03-01

Full Text Available There is a growing awareness in the field of neuroscience that the self-regulation of eating behavior is driven by complex networks within the brain. These networks may be vulnerable to hot states which people can move into and out of dynamically throughout the course of a day as a function of changes in affect or visceral cues. The goal of the current study was to identify and determine differences in the Hot-state Brain Network of Appetite (HBN-A that exists after a brief period of food restraint followed either by the consumption of a meal replacement (MR or water. Fourteen overweight/obese adults came to our laboratory on two different occasions. Both times they consumed a controlled breakfast meal and then were restricted from eating for 2.5 hours prior to an MRI scan. On one visit, they consumed a meal replacement (MR liquid meal after this period of food restriction; on the other visit they consumed an equal amount of water. After these manipulations, the participants underwent a resting fMRI scan. Our first study aim employed an exploratory, data-driven approach to identify hubs relevant to the HBN-A. Using data from the water condition, five regions were found to be the hubs or nodes of the HBN-A: insula, anterior cingulated cortex, the superior temporal pole, the amygdala, and the hippocampus. We then demonstrated that the consumption of a liquid MR dampened interconnectivity between the nodes of the HBN-A as compared to water. Importantly and consistent with these network data, the consumption of a MR beverage also lowered state cravings and hunger.

An investigation on the use of shredded waste PET bottles as aggregate in lightweight concrete

International Nuclear Information System (INIS)

Akcaoezoglu, Semiha; Atis, Cengiz Duran; Akcaoezoglu, Kubilay

2010-01-01

In this work, the utilization of shredded waste Poly-ethylene Terephthalate (PET) bottle granules as a lightweight aggregate in mortar was investigated. Investigation was carried out on two groups of mortar samples, one made with only PET aggregates and, second made with PET and sand aggregates together. Additionally, blast-furnace slag was also used as the replacement of cement on mass basis at the replacement ratio of 50% to reduce the amount of cement used and provide savings. The water-binder (w/b) ratio and PET-binder (PET/b) ratio used in the mixtures were 0.45 and 0.50, respectively. The size of shredded PET granules used in the preparation of mortar mixtures were between 0 and 4 mm. The results of the laboratory study and testing carried out showed that mortar containing only PET aggregate, mortar containing PET and sand aggregate, and mortars modified with slag as cement replacement can be drop into structural lightweight concrete category in terms of unit weight and strength properties. Therefore, it was concluded that there is a potential for the use of shredded waste PET granules as aggregate in the production of structural lightweight concrete. The use of shredded waste PET granules due to its low unit weight reduces the unit weight of concrete which results in a reduction in the death weight of a structural concrete member of a building. Reduction in the death weight of a building will help to reduce the seismic risk of the building since the earthquake forces linearly dependant on the dead-weight. Furthermore, it was also concluded that the use of industrial wastes such as PET granules and blast-furnace slag in concrete provides some advantages, i.e., reduction in the use of natural resources, disposal of wastes, prevention of environmental pollution, and energy saving.

An investigation on the use of shredded waste PET bottles as aggregate in lightweight concrete.

Science.gov (United States)

Akçaözoğlu, Semiha; Atiş, Cengiz Duran; Akçaözoğlu, Kubilay

2010-02-01

In this work, the utilization of shredded waste Poly-ethylene Terephthalate (PET) bottle granules as a lightweight aggregate in mortar was investigated. Investigation was carried out on two groups of mortar samples, one made with only PET aggregates and, second made with PET and sand aggregates together. Additionally, blast-furnace slag was also used as the replacement of cement on mass basis at the replacement ratio of 50% to reduce the amount of cement used and provide savings. The water-binder (w/b) ratio and PET-binder (PET/b) ratio used in the mixtures were 0.45 and 0.50, respectively. The size of shredded PET granules used in the preparation of mortar mixtures were between 0 and 4 mm. The results of the laboratory study and testing carried out showed that mortar containing only PET aggregate, mortar containing PET and sand aggregate, and mortars modified with slag as cement replacement can be drop into structural lightweight concrete category in terms of unit weight and strength properties. Therefore, it was concluded that there is a potential for the use of shredded waste PET granules as aggregate in the production of structural lightweight concrete. The use of shredded waste PET granules due to its low unit weight reduces the unit weight of concrete which results in a reduction in the death weight of a structural concrete member of a building. Reduction in the death weight of a building will help to reduce the seismic risk of the building since the earthquake forces linearly dependent on the dead-weight. Furthermore, it was also concluded that the use of industrial wastes such as PET granules and blast-furnace slag in concrete provides some advantages, i.e., reduction in the use of natural resources, disposal of wastes, prevention of environmental pollution, and energy saving.

COIN Project: Towards a zero-waste technology for concrete aggregate production in Norway

Science.gov (United States)

Cepuritis, Rolands; Willy Danielsen, Svein

2014-05-01

COIN Project: Towards a zero-waste technology for concrete aggregate production in Norway Rolands Cepuritis, Norcem/NTNU and Svein Willy Danielsen, SINTEF Aggregate production is a mining operation where no purification of the "ore" is necessary. Still it is extremely rare that an aggregate production plant is operating on the basis of zero-waste concept. This is since historically the fine crushed aggregate (particles with a size of less than 2, 4 or sometimes 8 mm) has been regarded as a by-product or waste of the more valuable coarse aggregate production. The reason is that the crushed coarse aggregates can easily replace coarse rounded natural stones in almost any concrete composition; while, the situation with the sand is different. The production of coarse aggregate normally yields fine fractions with rough surface texture, flaky or elongated particles an inadequate gradation. When such a material replaces smooth and rounded natural sand grains in a concrete mix, the result is usually poor and much more water and cement has to be used to achieve adequate concrete flow. The consequences are huge stockpiles of the crushed fine fractions that can't be sold (mass balance problems) for the aggregate producers, sustainability problems for the whole industry and environmental issues for society due to dumping and storing of the fine co-generated material. There have been attempts of utilising the material in concrete before; however, they have mostly ended up in failure. There have been attempts to adjust the crushed sand to the properties of the natural sand, which would still give a lot of waste, especially if the grading would have to be adjusted and the high amounts of fines abundantly present in the crushed sand would have to be removed. Another fundamental reason for failure has been that historically such attempts have mainly ended up in a research carried out by people (both industrial and academic) with aggregate background (= parties willing to find market

Properties of lightweight aggregate concrete prepared with PVC granules derived from scraped PVC pipes.

Science.gov (United States)

Kou, S C; Lee, G; Poon, C S; Lai, W L

2009-02-01

This paper aims to investigate the fresh and hardened properties of lightweight aggregate concretes that are prepared with the use of recycled plastic waste sourced from scraped PVC pipes to replace river sand as fine aggregates. A number of laboratory prepared concrete mixes were tested, in which river sand was partially replaced by PVC plastic waste granules in percentages of 0%, 5%, 15%, 30% and 45% by volume. Two major findings are identified. The positive side shows that the concrete prepared with a partial replacement by PVC was lighter (lower density), was more ductile (greater Poisson's ratios and reduced modulus of elasticity), and had lower drying shrinkage and higher resistance to chloride ion penetration. The negative side reveals that the workability, compressive strength and tensile splitting strength of the concretes were reduced. The results gathered would form a part of useful information for recycling PVC plastic waste in lightweight concrete mixes.

Feasibility of reclaimed asphalt pavement as aggregate in portland cement concrete pavements.

Science.gov (United States)

2013-11-01

This research effort was focused on evaluating the feasibility of using minimally processed reclaimed : asphalt pavement (RAP) as aggregate replacement in concrete pavements. This research demonstrated : that concretes with up to 50 percent of the fi...

Recycling ground granulated blast furnace slag as cold bonded artificial aggregate partially used in self-compacting concrete.

Science.gov (United States)

Gesoğlu, Mehmet; Güneyisi, Erhan; Mahmood, Swara Fuad; Öz, Hatice Öznur; Mermerdaş, Kasım

2012-10-15

Ground granulated blast furnace slag (GGBFS), a by-product from iron industry, was recycled as artificial coarse aggregate through cold bonding pelletization process. The artificial slag aggregates (ASA) replaced partially the natural coarse aggregates in production of self-compacting concrete (SCC). Moreover, as being one of the most widely used mineral admixtures in concrete industry, fly ash (FA) was incorporated as a part of total binder content to impart desired fluidity to SCCs. A total of six concrete mixtures having various ASA replacement levels (0%, 20%, 40%, 60%, and 100%) were designed with a water-to-binder (w/b) ratio of 0.32. Fresh properties of self-compacting concretes (SCC) were observed through slump flow time, flow diameter, V-funnel flow time, and L-box filling height ratio. Compressive strength of hardened SCCs was also determined at 28 days of curing. It was observed that increasing the replacement level of ASA resulted in decrease in the amount of superplasticizer to achieve a constant slump flow diameter. Moreover, passing ability and viscosity of SCC's enhanced with increasing the amount of ASA in the concrete. The maximum compressive strength was achieved for the SCC having 60% ASA replacement. Copyright © 2012 Elsevier B.V. All rights reserved.

Ceramic ware waste as coarse aggregate for structural concrete production.

Science.gov (United States)

García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia M; Guerra-Romero, M Ignacio

2015-01-01

The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste.

Generation and exploration of aggregation abstractions for scheduling and resource allocation

Science.gov (United States)

Lowry, Michael R.; Linden, Theodore A.

1993-01-01

This paper presents research on the abstraction of computational theories for scheduling and resource allocation. The paper describes both theory and methods for the automated generation of aggregation abstractions and approximations in which detailed resource allocation constraints are replaced by constraints between aggregate demand and capacity. The interaction of aggregation abstraction generation with the more thoroughly investigated abstractions of weakening operator preconditions is briefly discussed. The purpose of generating abstract theories for aggregated demand and resources includes: answering queries about aggregate properties, such as gross feasibility; reducing computational costs by using the solution of aggregate problems to guide the solution of detailed problems; facilitating reformulating theories to approximate problems for which there are efficient problem-solving methods; and reducing computational costs of scheduling by providing more opportunities for variable and value-ordering heuristics to be effective. Experiments are being developed to characterize the properties of aggregations that make them cost effective. Both abstract and concrete theories are represented in a variant of first-order predicate calculus, which is a parameterized multi-sorted logic that facilitates specification of large problems. A particular problem is conceptually represented as a set of ground sentences that is consistent with a quantified theory.

Development of lightweight concrete subfloor with ethylene vinyl acetate (EVA) aggregates waste to reduce impact sound in flooring system

OpenAIRE

Pacheco, Fernanda; Krumenauer, Marcelo; Reis de Medeiros, Daniel; Oliveira, Maria Fernanda; Fonseca Tutikian, Bernardo

2017-01-01

Abstract Comfort and habitability are requirements for housing quality, affected by underfloor system. Thus, this study aims to design lightweight concrete slabs underfloor with the use of ethylene vinyl acetate (EVA) aggregates, with two grain sizes of conventional aggregates replaced with EVA. The experimental counted on four unit mixes, varying the ratio between EVA coarse and fine aggregates and natural aggregates. The underfloor plates were molded with thickness of 3, 5 and 7 centimeters...

Viral aggregating and opsonizing activity in collectin trimers

DEFF Research Database (Denmark)

Hartshorn, Kevan L; White, Mitchell R; Tecle, Tesfaldet

2010-01-01

of bovine serum collectin CL-46 induces aggregation of influenza A virus (IAV) and potently increases IAV uptake by neutrophils. CL-46-NCRD showed calcium-dependent and sugar-sensitive binding to both neutrophils and IAV. Replacement of specific residues of the CRD of human SP-D with those found in bovine...... were further increased by cross-linking of hSP-D-NCRD/R343V trimers with mAbs directed against areas of the hSP-D-NCRD not involved in viral binding. Unlike the wild-type human SP-D hSP-D-NCRD, hSP-D-NCRD/R343V also induced viral aggregation. These results indicate that collectins can act as opsonins...

Proteins aggregation and human diseases

International Nuclear Information System (INIS)

Hu, Chin-Kun

2015-01-01

Many human diseases and the death of most supercentenarians are related to protein aggregation. Neurodegenerative diseases include Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), frontotemporallobar degeneration, etc. Such diseases are due to progressive loss of structure or function of neurons caused by protein aggregation. For example, AD is considered to be related to aggregation of Aβ40 (peptide with 40 amino acids) and Aβ42 (peptide with 42 amino acids) and HD is considered to be related to aggregation of polyQ (polyglutamine) peptides. In this paper, we briefly review our recent discovery of key factors for protein aggregation. We used a lattice model to study the aggregation rates of proteins and found that the probability for a protein sequence to appear in the conformation of the aggregated state can be used to determine the temperature at which proteins can aggregate most quickly. We used molecular dynamics and simple models of polymer chains to study relaxation and aggregation of proteins under various conditions and found that when the bending-angle dependent and torsion-angle dependent interactions are zero or very small, then protein chains tend to aggregate at lower temperatures. All atom models were used to identify a key peptide chain for the aggregation of insulin chains and to find that two polyQ chains prefer anti-parallel conformation. It is pointed out that in many cases, protein aggregation does not result from protein mis-folding. A potential drug from Chinese medicine was found for Alzheimer's disease. (paper)

Proteins aggregation and human diseases

Science.gov (United States)

Hu, Chin-Kun

2015-04-01

Many human diseases and the death of most supercentenarians are related to protein aggregation. Neurodegenerative diseases include Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), frontotemporallobar degeneration, etc. Such diseases are due to progressive loss of structure or function of neurons caused by protein aggregation. For example, AD is considered to be related to aggregation of Aβ40 (peptide with 40 amino acids) and Aβ42 (peptide with 42 amino acids) and HD is considered to be related to aggregation of polyQ (polyglutamine) peptides. In this paper, we briefly review our recent discovery of key factors for protein aggregation. We used a lattice model to study the aggregation rates of proteins and found that the probability for a protein sequence to appear in the conformation of the aggregated state can be used to determine the temperature at which proteins can aggregate most quickly. We used molecular dynamics and simple models of polymer chains to study relaxation and aggregation of proteins under various conditions and found that when the bending-angle dependent and torsion-angle dependent interactions are zero or very small, then protein chains tend to aggregate at lower temperatures. All atom models were used to identify a key peptide chain for the aggregation of insulin chains and to find that two polyQ chains prefer anti-parallel conformation. It is pointed out that in many cases, protein aggregation does not result from protein mis-folding. A potential drug from Chinese medicine was found for Alzheimer's disease.

Effect of bulky substituents on thiopyrylium polymethine aggregation in the solid state: A theoretical evaluation of the implications for all-optical switching applications

KAUST Repository

Gieseking, Rebecca L.

2014-11-25

Polymethine dyes in dilute solutions display many of the optical properties required for all-optical switching applications. However, in thin films, aggregation and polymethine-counterion interactions can substantially modify their properties and limit their utility. Here, we examine the impact of a series of bulky substituents on the solid-state molecular packing of thiopyrylium polymethines by using a theoretical approach combining molecular-dynamics simulations and quantum-chemical calculations. Importantly, it is found that the positions of the substituents near the center and/or ends of the dye determine the extent to which aggregation is reduced; in particular, substituents near the polymethine center primarily modify the type of aggregation that is observed, while substituents near the polymethine ends reduce aggregation and aid in maintaining solution-like properties in the solid state. Our theoretical study elucidates relationships between molecular structure and bulk optical properties and provides design guidelines for all-optical switching materials.

Lightweight concrete with Algerian limestone dust: Part I: Study on 30% replacement to normal aggregate at early age

Directory of Open Access Journals (Sweden)

S. Kitouni

2013-12-01

Full Text Available The mechanical characteristics of the lightweight aggregate concretes (LWAC strongly depend on the proportions of aggregates in the formulation. In particular, because of their strong porosity, the lightweight aggregates are much more deformable than the cementations matrix and their influence on concrete strength is complex. This paper focuses on studying the physical performance of concrete formulated with substitution of 30% of coarse aggregates by limestone dust. In this article an attempt is made to provide information on the elastic properties of lightweight concrete (LWC from tests carried out under uniaxial compression conditions. The results of Young modulus, Poisson's ratio, and compressive and flexural tensile strength tests on concrete are presented. The concretes obtained present good mechanical performances reaching 34.99 MPa compressive strength, 6.39 MPa flexural tensile strength and in front of 36 MPa Young modulus.

Computational study of energy transfer in two-dimensional J-aggregates

International Nuclear Information System (INIS)

Gallos, Lazaros K.; Argyrakis, Panos; Lobanov, A.; Vitukhnovsky, A.

2004-01-01

We perform a computational analysis of the intra- and interband energy transfer in two-dimensional J-aggregates. Each aggregate is represented as a two-dimensional array (LB-film or self-assembled film) of two kinds of cyanine dyes. We consider the J-aggregate whose J-band is located at a shorter wavelength to be a donor and an aggregate or a small impurity with longer wavelength to be an acceptor. Light absorption in the blue wing of the donor aggregate gives rise to the population of its excitonic states. The depopulation of these states is possible by (a) radiative transfer to the ground state (b) intraband energy transfer, and (c) interband energy transfer to the acceptor. We study the dependence of energy transfer on properties such as the energy gap, the diagonal disorder, and the exciton-phonon interaction strength. Experimentally observable parameters, such as the position and form of luminescence spectrum, and results of the kinetic spectroscopy measurements strongly depend upon the density of states in excitonic bands, rates of energy exchange between states and oscillator strengths for luminescent transitions originating from these states

Applicability of recycled aggregates in concrete piles for soft soil improvement.

Science.gov (United States)

Medeiros-Junior, Ronaldo A; Balestra, Carlos Et; Lima, Maryangela G

2017-01-01

The expressive generation of construction and demolition waste is stimulating several studies for reusing this material. The improvement of soft soils by concrete compaction piles has been widely applied for 40 years in some Brazilian cities. This technique is used to improve the bearing capacity of soft soils, allowing executing shallow foundations instead of deep foundations. The compaction piles use a high volume of material. This article explored the possibility of using recycled aggregates from construction waste to replace the natural aggregates in order to improve the bearing capacity of the soft soil, regarding its compressive strength. Construction wastes from different stages of a construction were used in order to make samples of concrete with recycled aggregates. The strength of concretes with natural aggregates was compared with the strength of concretes with recycled (fine and coarse) aggregates. Results show that all samples met the minimum compressive strength specified for compaction piles used to improve the bearing capacity of soft soils. The concrete with recycled aggregate from the structural stage had even higher resistances than the concrete with natural aggregates. This behaviour was attributed to the large amount of cementitious materials in the composition of this type of concrete. It was also observed that concrete with recycled fine aggregate has a superior resistance to concrete with recycled coarse aggregate.

ALPHA-SYNUCLEIN STRUCTURE, AGGREGATION AND MODULATORS

Directory of Open Access Journals (Sweden)

Pinakin K. Makwana

2016-06-01

Full Text Available Alpha-synuclein is an intrinsically unstructured protein, involved in various neurodegenerative disorders. In vitro/in vivo experiments, as well as genetic mutation studies establish a direct link between alphasynuclein and synucleinopathies. Due to its natively unfolded state, alpha synuclein can adopt numerous conformations upon interaction with its partners and cellular factors, offering explanation for its diverse interactions. Aggregated form of alpha-synuclein has been observed in the brain of patients with synucleinopathies, a hallmark of neurodegeneration, and cell death has been attributed to aggregation induced toxicity. The process of aggregation involves nucleation, followed by intermediate oligomeric states, and finally the fibrillar amyloids. Of the various conformations/species that alpha-synuclein assumes before it transforms into mature amyloid fibrils, the oligomeric species is the most toxic. Thus, an effective way to limit disease progression is by modifying/slowing down protein aggregation/deposition in the brain. Various small natural products, synthetic chemicals, peptides and antibodies specific to alpha-synuclein have been designed/identified to reduce its rate of aggregation. Unfortunately, not even a handful of the molecules have cleared the clinical trials. Even today, medications available for Parkinson’s patients are mostly the drugs that adjust for loss of dopamine in the brain, and hence do not stop the progression of the disease or cure the symptoms. Thus, more molecular level studies are warranted to fully elucidate the process of alpha-synuclein aggregation, which in turn could help in identifying novel therapeutics and preventives. The present review summarizes the insights gained into the structure, in vitro aggregation and inhibitors/modulators of alpha-synuclein aggregation, that can be used to design better and effective inhibitors against the diseases.

Mutations of Profilin-1 Associated with Amyotrophic Lateral Sclerosis Promote Aggregation Due to Structural Changes of Its Native State.

Science.gov (United States)

Del Poggetto, Edoardo; Bemporad, Francesco; Tatini, Francesca; Chiti, Fabrizio

2015-11-20

The PFN1 gene, coding for profilin-1, has recently been associated with familial amyotrophic lateral sclerosis (fALS), as three mutations, namely C71G, M114T, and G118V, have been found in patients with familial forms of the disease and another, E117G, has been proposed to be a moderate risk factor for disease onset. In this work, we have purified the four profilin-1 variants along with the wild-type protein. The resulting aggregates appear to be fibrillar, to have a weak binding to ThT, and to possess a significant amount of intermolecular β-sheet structure. Using ThT fluorescence assays, far-UV circular dichroism, and dynamic light scattering, we found that all four variants have an aggregation propensity higher than that of the wild-type counterpart. In particular, the C71G mutation was found to induce the most dramatic change in aggregation, followed by the G118V and M114T substitutions and then the E117G mutation. Such a propensity was found not to strictly correlate with the conformational stability in this group of profilin-1 variants, determined using both urea-induced denaturation at equilibrium and folding/unfolding kinetics. However, it correlated with structural changes of the folded states, as monitored with far-UV circular dichroism, intrinsic fluorescence spectroscopy, ANS binding, acrylamide quenching, and dynamic light scattering. Overall, the results suggest that all four mutations increase the tendency of profilin-1 to aggregate and that such aggregation behavior is largely determined by the mutation-induced structural changes occurring in the folded state of the protein.

Effects of waste PET bottles aggregate on the properties of concrete

International Nuclear Information System (INIS)

Choi, Yun-Wang; Moon, Dae-Joong; Chung, Jee-Seung; Cho, Sun-Kyu

2005-01-01

This paper investigates the surface microstructure of waste polyethylene terephthalate (PET) bottles lightweight aggregate (WPLA) to examine the effect of granulated blast-furnace slag (GBFS) on WPLA. The WPLA was made from the waste PET bottles and GBFS, and experimental tests were conducted on compressive strength, splitting tensile strength, modulus of elasticity, slump, and density of waste PET bottles lightweight aggregate concrete (WPLAC). The 28-day compressive strength of WPLAC with the replacement ratio of 75% reduces about 33% compared to the control concrete in the water-cement ratio of 45%. The density of WPLAC varies from 1940 to 2260 kg/m 3 by the influence of WPLA. The structural efficiency of WPLAC decreases as the replacement ratio increases. The workability of concrete with 75% WPLA improves about 123% compared to that of the normal concrete in the water-cement ratio of 53%. The adhered GBFS is able to strengthen the surface of WPLA and to narrow the transition zone owing to the reaction with calcium hydroxide

Evaluating the Carbonation Resistance of Self Compacting Concrete made with Recycled Concrete Aggregates

Directory of Open Access Journals (Sweden)

S P Singh

2016-07-01

Full Text Available The paper presents the results of an investigation conducted to examine carbonation resistance of Self Compacting Concrete (SCC made with coarse Recycled Concrete Aggregates (RCA. In total, five SCC mixes were prepared by systematically replacing coarse Natural Aggregates (NA by RCA at 0, 25, 50, 75 and 100%. In order to measure the carbonation resistance of SCC made with RCA, accelerated carbonation tests were performed for 4 and 12 weeks of exposure to carbon dioxide. The carbonation resistance has been evaluated after curing periods of 28 and 90 days. In addition to this, the compressive strength of all the mixes was also obtained after 7, 28 and 90 days of curing and ultra-sonic pulse velocity tests (UPV were also conducted. The results indicate that with the increase in the content of RCA as replacement of NA, decrease in the carbonation resistance, compressive strength and UPV was observed for all SCC mixes. It has been observed that the SCC mixes containing low percentages of RCA (i.e. 25% as replacement of NA do not impart detrimental behaviour in the overall performance but higher replacement levels (>50% have been found to deteriorate the performance in terms of carbonation resistance, compressive strength and UPV.

Bio-aggregates based building materials state-of-the-art report of the RILEM Technical Committee 236-BBM

CERN Document Server

Collet, Florence

2017-01-01

The work of the RILEM Technical Committee (TC -236 BBM) was dedicated to the study of construction materials made from plant particles. It considered the question whether building materials containing as main raw material recyclable and easily available plant particles are renewable. This book includes a state-of-the-art report and an appendix. The state-of-the-art report relates to the description of vegetal aggregates. Then, hygrothermal properties, fire resistance, durability and finally the impact of the variability of the method of production of bio-based concrete are assessed. The appendix is a TC report which presents the experience of a working group. The goal was to define testing methods for the measurement of water absorption, bulk density, particle size distribution, and thermal conductivity of bio aggregates. The work is based on a first round robin test of the TC-BBM where the protocols in use by the different laboratories (labs) are compared. .

An audit of some processing effects in aggregated occurrence records.

Science.gov (United States)

Mesibov, Robert

2018-01-01

A total of ca 800,000 occurrence records from the Australian Museum (AM), Museums Victoria (MV) and the New Zealand Arthropod Collection (NZAC) were audited for changes in selected Darwin Core fields after processing by the Atlas of Living Australia (ALA; for AM and MV records) and the Global Biodiversity Information Facility (GBIF; for AM, MV and NZAC records). Formal taxon names in the genus- and species-groups were changed in 13-21% of AM and MV records, depending on dataset and aggregator. There was little agreement between the two aggregators on processed names, with names changed in two to three times as many records by one aggregator alone compared to records with names changed by both aggregators. The type status of specimen records did not change with name changes, resulting in confusion as to the name with which a type was associated. Data losses of up to 100% were found after processing in some fields, apparently due to programming errors. The taxonomic usefulness of occurrence records could be improved if aggregators included both original and the processed taxonomic data items for each record. It is recommended that end-users check original and processed records for data loss and name replacements after processing by aggregators.

Recycled construction and demolition concrete waste as aggregate for structural concrete

Directory of Open Access Journals (Sweden)

Ashraf M. Wagih

2013-12-01

Full Text Available In major Egyptian cities there is a surge in construction and demolition waste (CDW quantities causing an adverse effect on the environment. The use of such waste as recycled aggregate in concrete can be useful for both environmental and economical aspects in the construction industry. This study discusses the possibility to replace natural coarse aggregate (NA with recycled concrete aggregate (RCA in structural concrete. An investigation into the properties of RCA is made using crushing and grading of concrete rubble collected from different demolition sites and landfill locations around Cairo. Aggregates used in the study were: natural sand, dolomite and crushed concretes obtained from different sources. A total of 50 concrete mixes forming eight groups were cast. Groups were designed to study the effect of recycled coarse aggregates quality/content, cement dosage, use of superplasticizer and silica fume. Tests were carried out for: compressive strength, splitting strength and elastic modulus. The results showed that the concrete rubble could be transformed into useful recycled aggregate and used in concrete production with properties suitable for most structural concrete applications in Egypt. A significant reduction in the properties of recycled aggregate concrete (RAC made of 100% RCA was seen when compared to natural aggregate concrete (NAC, while the properties of RAC made of a blend of 75% NA and 25% RCA showed no significant change in concrete properties.

Characterization of fine aggregates in concrete by different experimental approaches

OpenAIRE

He, Huan; Courard, Luc; Pirard, Eric; Michel, Frédéric

2011-01-01

Being its major component, aggregate can occupy up to three-quarter of the volume of concrete. The structure of aggregate formed in hardened state impacts largely on mechanical and durability properties of concrete. On another hand, physical characteristics of aggregate are primarily assumed to be relevant to granular behavior of aggregate. Therefore, characterization of aggregate is of high relevance to concrete studies. In this study, different types of fine aggregate used in concrete, name...

Comparative performance of various smart aggregates during strength gain and damage states of concrete

International Nuclear Information System (INIS)

Saravanan, T Jothi; Balamonica, K; Priya, C Bharathi; Gopalakrishnan, N; Reddy, A Likhith

2015-01-01

Information regarding the early strength gain of fresh concrete determines the time for the removal of form work and the transfer of pre-stressing forces for pre-stressed concrete. An ultrasonic based non-destructive evaluation of early strength gain may not work for concrete in fluid and semi-solid phases. A possible alternative is a lead zirconate titanate (PZT)-based smart aggregate embedded in concrete, which can evaluate the micro-structural and rheological properties right from the fluid phase. A set of five smart aggregates embedded in a concrete cube were investigated for their suitability to evaluate electromechanical impedance (EMI) signatures. Cubes were loaded to failure and the EMI during progressive strength loss under compressive loads was studied. To show the generalized applicability of this, experimental results for the performance of typical smart aggregates on a larger specimen, namely a concrete beam, are also discussed. Different statistical metrics were examined computationally on a three peak admittance curve with a parametric variation of stiffness, damping and simple scaling. The root mean square deviation (RMSD), mean absolute percentage deviation (MAPD), cross correlation (CC) and modified cross correlation (MCC) were investigated, in addition to the rate of change of the RMSD. Variations between the reference and modified states were studied. Both stiffness and mass gains occur for the smart aggregates, resulting in an increase or decrease of frequency and amplitude peaks due to progressive C-S-H gel formation. The trend of increasing stiffness and the consequent rightward shift of the resonant peaks and decrease of damping, with the consequent upward shift of amplitudes that happens during curing and strength gain, was observed to be reversed during the application of damaging loads. (paper)

Entanglement dynamics of J-aggregate systems

Energy Technology Data Exchange (ETDEWEB)

Thilagam, A, E-mail: Thilagam.Lohe@unisa.edu.au [Information Technology, Engineering and the Environment, Mawson Institute, University of South Australia, South Australia 5095 (Australia)

2011-04-01

The entanglement dynamics of one-dimensional J-aggregate systems are examined using entanglement measures such as the von Neumann entropy and Wootters concurrence. The effect of dispersion and resonance terms associated with the exciton-phonon interaction are analyzed using Green's function formalism. A probability propagator term, derived using the Markovian approximation, presents J-aggregate systems as potential channels for large scale energy propagation for a select range of parameters. We highlight the role of a critical number of coherently coupled monomer sites and two-exciton states in determining superradiance in J-aggregate systems.

Microstructure and mechanical properties of recycled aggregate concrete in seawater environment.

Science.gov (United States)

Yue, Pengjun; Tan, Zhuoying; Guo, Zhiying

2013-01-01

This study aims to conduct research about the microstructure and basic properties of recycled aggregate concrete under seawater corrosion. Concrete specimens were fabricated and tested with different replacement percentages of 0%, 30%, and 60% after immersing in seawater for 4, 8, 12, and 16 months, respectively. The basic properties of recycled aggregate concrete (RAC) including the compressive strength, the elastic modulus, and chloride penetration depth were explicitly investigated. And the microstructure of recycled concrete aggregate (RCA) was revealed to find the seawater corrosion by using scanning electron microscope (SEM). The results showed that higher amount of the RCA means more porosity and less strength, which could lower both the compressive strength and resistance to chloride penetration. This research could be a guide in theoretical and numerical analysis for the design of RAC structures.

Engineering Behavior of Concrete with Recycled Aggregate

Directory of Open Access Journals (Sweden)

Ayob Afizah

2017-01-01

Full Text Available Concrete is extensively used as construction materials in Malaysia. Concrete contributes suitable feature for construction industry for instance durability, adequate compressive strength, fire resistance, availability and is economic as compared to other construction materials. Depletion of natural resources and disposal of construction and demolition waste remarkably claim environmental threat. In this paper, the engineering behavior, durability, and concrete microstructure of recycled concrete aggregates (RCA on short-term concrete properties were investigated. The studied concrete at design mix proportion of 1:0.55:2.14:2.61 (weight of cement :coarse aggregates :sand :water used to obtain medium-high compressive strength with 20%, 50%, and 100% of RCA. Results show that for the same water/cement ratio, RCA replacement up to 50% still achieved the targeted compressive strength of 25 MPa at 28 curing days. Addition, at similar RCA replacement, the highest carbonation depth value was found at 1.03 mm which could be attributed to the pozzolanic reaction, thus led to lower carbonation resistance. Scanning electron microscopy microstructure shows that the RCA surface was porous and covered with loose particles. Moreover, the interfacial transition zone was composed of numerous small pores, micro cracks, and fissures that surround the mortar matrix. On the basis of the obtained results, recommendable mineral admixtures of RCA are necessary to enhance the quality of concrete construction.

Effect of Coating Palm Oil Clinker Aggregate on the Engineering Properties of Normal Grade Concrete

Directory of Open Access Journals (Sweden)

Fuad Abutaha

2017-10-01

Full Text Available Palm oil clinker (POC is a waste material generated in large quantities from the palm oil industry. POC, when crushed, possesses the potential to serve as an aggregate for concrete production. Experimental investigation on the engineering properties of concrete incorporating POC as aggregate and filler material was carried out in this study. POC was partially and fully used to replace natural coarse aggregate. The volumetric replacements used were 0%, 20%, 40%, 60%, 80%, and 100%. POC, being highly porous, negatively affected the fresh and hardened concrete properties. Therefore, the particle-packing (PP method was adopted to measure the surface and inner voids of POC coarse aggregate in the mixtures at different substitution levels. In order to enhance the engineering properties of the POC concrete, palm oil clinker powder (POCP was used as a filler material to fill up and coat the surface voids of POC coarse, while the rest of the mix constituents were left as the same. Fresh and hardened properties of the POC concrete with and without coating were determined, and the results were compared with the control concrete. The results revealed that coating the surface voids of POC coarse with POCP significantly improved the engineering properties as well as the durability performance of the POC concrete. Furthermore, using POC as an aggregate and filler material may reduce the continuous exploitation of aggregates from primary sources. Also, this approach offers an environmental friendly solution to the ongoing waste problems associated with palm oil waste material.

Rapid Aggregation of Biofuel-Producing Algae by the Bacterium Bacillus sp. Strain RP1137

Science.gov (United States)

Powell, Ryan J.

2013-01-01

Algal biofuels represent one of the most promising means of sustainably replacing liquid fuels. However, significant challenges remain before alga-based fuels become competitive with fossil fuels. One of the largest challenges is the ability to harvest the algae in an economical and low-energy manner. In this article, we describe the isolation of a bacterial strain, Bacillus sp. strain RP1137, which can rapidly aggregate several algae that are candidates for biofuel production, including a Nannochloropsis sp. This bacterium aggregates algae in a pH-dependent and reversible manner and retains its aggregation ability after paraformaldehyde fixation, opening the possibility for reuse of the cells. The optimal ratio of bacteria to algae is described, as is the robustness of aggregation at different salinities and temperatures. Aggregation is dependent on the presence of calcium or magnesium ions. The efficiency of aggregation of Nannochloropsis oceanica IMET1 is between 70 and 95% and is comparable to that obtained by other means of harvest; however, the rate of harvest is fast, with aggregates forming in 30 s. PMID:23892750

Study on Characteristics of Lightweight Aggregate Concrete Made From Foam and Ordinary Portland Cement

Directory of Open Access Journals (Sweden)

Ibrahim N.M.

2016-01-01

Full Text Available The production and characteristic of lightweight bubble aggregates (LBA are presented in this paper. The LBA are produced by mixing between the foam and ordinary Portland cement according to the composition which has been set. Then, the characteristics of LBA such as density, water absorption, specific gravity, compressive strength, aggregate impact value and microscopic analysis of the LBA are analyzed. Those characteristics are identified in order to ensure that the LBA are successfully categorized into lightweight aggregate. The loose bulk density is obtained at 812.5 kg/m3 which can be categorized under lightweight aggregate group. For water absorption the value obtained is 9.7 % which is slightly higher compared to normal aggregate. Meanwhile the average specific gravity obtained for the samples of LBAis 1.75. Compressive strength for the aggregates was 17.76 MPa. The highest compressive strength for LBA foamed concrete was obtained at 25% replacement with 7.83MPa. Thus, the LBA have a significant features and characteristics that can be used as coarse aggregates in concrete.

SHAPE CHARACTERIZATION OF CONCRETE AGGREGATE

Directory of Open Access Journals (Sweden)

Jing Hu

2011-05-01

Full Text Available As a composite material, the performance of concrete materials can be expected to depend on the properties of the interfaces between its two major components, aggregate and cement paste. The microstructure at the interfacial transition zone (ITZ is assumed to be different from the bulk material. In general, properties of conventional concrete have been found favoured by optimum packing density of the aggregate. Particle size is a common denominator in such studies. Size segregation in the ITZ among the binder particles in the fresh state, observed in simulation studies by concurrent algorithm-based SPACE system, additionally governs density as well as physical bonding capacity inside these shell-like zones around aggregate particles. These characteristics have been demonstrated qualitatively pertaining also after maturation of the concrete. Such properties of the ITZs have direct impact on composite properties. Despite experimental approaches revealed effects of aggregate grain shape on different features of material structure (among which density, and as a consequence on mechanical properties, it is still an underrated factor in laboratory studies, probably due to the general feeling that a suitable methodology for shape characterization is not available. A scientific argument hindering progress is the interconnected nature of size and shape. Presently, a practical problem preventing shape effects to be emphasized is the limitation of most computer simulation systems in concrete technology to spherical particles. New developments at Delft University of Technology will make it possible in the near future to generate jammed states, or other high-density fresh particle mixtures of non-spherical particles, which thereupon can be subjected to hydration algorithms. This paper will sketch the outlines of a methodological approach for shape assessment of loose (non-embedded aggregate grains, and demonstrate its use for two types of aggregate, allowing

Enhanced solid-state order and field-effect hole mobility through control of nanoscale polymer aggregation

KAUST Repository

Chen, Mark S.

2013-12-26

Efficient charge carrier transport in organic field-effect transistors (OFETs) often requires thin films that display long-range order and close π-π packing that is oriented in-plane with the substrate. Although some polymers have achieved high field-effect mobility with such solid-state properties, there are currently few general strategies for controlling the orientation of π-stacking within polymer films. In order to probe structural effects on polymer-packing alignment, furan-containing diketopyrrolopyrrole (DPP) polymers with similar optoelectronic properties were synthesized with either linear hexadecyl or branched 2-butyloctyl side chains. Differences in polymer solubility were observed and attributed to variation in side-chain shape and polymer backbone curvature. Averaged field-effect hole mobilities of the polymers range from 0.19 to 1.82 cm2/V·s, where PDPP3F-C16 is the least soluble polymer and provides the highest maximum mobility of 2.25 cm2/V·s. Analysis of the films by AFM and GIXD reveal that less soluble polymers with linear side chains exhibit larger crystalline domains, pack considerably more closely, and align with a greater preference for in-plane π-π packing. Characterization of the polymer solutions prior to spin-coating shows a correlation between early onset nanoscale aggregation and the formation of films with highly oriented in-plane π-stacking. This effect is further observed when nonsolvent is added to PDPP3F-BO solutions to induce aggregation, which results in films with increased nanostructural order, in-plane π-π orientation, and field-effect hole mobilities. Since nearly all π-conjugated materials may be coaxed to aggregate, this strategy for enhancing solid-state properties and OFET performance has applicability to a wide variety of organic electronic materials. © 2013 American Chemical Society.

Enhanced solid-state order and field-effect hole mobility through control of nanoscale polymer aggregation

KAUST Repository

Chen, Mark S.; Lee, Olivia P.; Niskala, Jeremy R.; Yiu, Alan T.; Tassone, Christopher J.; Schmidt, Kristin; Beaujuge, Pierre M.; Onishi, Seita S.; Toney, Michael F.; Zettl, Alex K.; Frechet, Jean

2013-01-01

Efficient charge carrier transport in organic field-effect transistors (OFETs) often requires thin films that display long-range order and close π-π packing that is oriented in-plane with the substrate. Although some polymers have achieved high field-effect mobility with such solid-state properties, there are currently few general strategies for controlling the orientation of π-stacking within polymer films. In order to probe structural effects on polymer-packing alignment, furan-containing diketopyrrolopyrrole (DPP) polymers with similar optoelectronic properties were synthesized with either linear hexadecyl or branched 2-butyloctyl side chains. Differences in polymer solubility were observed and attributed to variation in side-chain shape and polymer backbone curvature. Averaged field-effect hole mobilities of the polymers range from 0.19 to 1.82 cm2/V·s, where PDPP3F-C16 is the least soluble polymer and provides the highest maximum mobility of 2.25 cm2/V·s. Analysis of the films by AFM and GIXD reveal that less soluble polymers with linear side chains exhibit larger crystalline domains, pack considerably more closely, and align with a greater preference for in-plane π-π packing. Characterization of the polymer solutions prior to spin-coating shows a correlation between early onset nanoscale aggregation and the formation of films with highly oriented in-plane π-stacking. This effect is further observed when nonsolvent is added to PDPP3F-BO solutions to induce aggregation, which results in films with increased nanostructural order, in-plane π-π orientation, and field-effect hole mobilities. Since nearly all π-conjugated materials may be coaxed to aggregate, this strategy for enhancing solid-state properties and OFET performance has applicability to a wide variety of organic electronic materials. © 2013 American Chemical Society.

Use of rubber asphalt binder with graded aggregate for seal coats

Energy Technology Data Exchange (ETDEWEB)

1979-01-01

It has been known that incorporating rubber particles into asphalt can improve highway pavement performance. This paper describes a test program on pavement construction using asphalts containing recycled rubber. During the summer 1978, eight test sections were constructed in parts of the Saskatchewan road system to evaluate seal coats using rubber-asphalt as a binder membrane and a graded aggregate as protective cover. Test sections were chosen to represent typical road surface types and different states of repair for each type. These types included prime subgrade, cold-mix on subgrade, primed granular base course, asphaltic concrete on granular base, and full depth asphaltic concrete. Problems with construction materials, techniques, and equipment are discussed. Performance and economics were evaluated to determine whether low cost cold mix and current seal coat surfaces could be replaced successfully and economically by this method of construction. It was shown that use of reclaimed rubber for rubberized asphalt seal coats on Saskatechewan highways is a practical construction application. The economic justification for rubber asphalt seals will be determined after a full assessment of performance. Initial indications are that Saskatchewan graded aggregates are a suitable cover material for the rubberized asphalt membranes used in the trials. 8 refs., 16 figs., 7 tabs.

Effects of Gradient Coil Noise and Gradient Coil Replacement on the Reproducibility of Resting State Networks.

Science.gov (United States)

Bagarinao, Epifanio; Tsuzuki, Erina; Yoshida, Yukina; Ozawa, Yohei; Kuzuya, Maki; Otani, Takashi; Koyama, Shuji; Isoda, Haruo; Watanabe, Hirohisa; Maesawa, Satoshi; Naganawa, Shinji; Sobue, Gen

2018-01-01

The stability of the MRI scanner throughout a given study is critical in minimizing hardware-induced variability in the acquired imaging data set. However, MRI scanners do malfunction at times, which could generate image artifacts and would require the replacement of a major component such as its gradient coil. In this article, we examined the effect of low intensity, randomly occurring hardware-related noise due to a faulty gradient coil on brain morphometric measures derived from T1-weighted images and resting state networks (RSNs) constructed from resting state functional MRI. We also introduced a method to detect and minimize the effect of the noise associated with a faulty gradient coil. Finally, we assessed the reproducibility of these morphometric measures and RSNs before and after gradient coil replacement. Our results showed that gradient coil noise, even at relatively low intensities, could introduce a large number of voxels exhibiting spurious significant connectivity changes in several RSNs. However, censoring the affected volumes during the analysis could minimize, if not completely eliminate, these spurious connectivity changes and could lead to reproducible RSNs even after gradient coil replacement.

Physicochemical characterization of steel slag post-processed as aggregate for sustainable concrete

International Nuclear Information System (INIS)

Souza, B.P. de; Fontes, W.C.; Carvalho, J.M.F. de; Mol, R.M.R.; Costa, E.C.P. da; Peixoto, R.A.F.

2016-01-01

The concrete is the material most widely used in construction, consuming a large amount of natural resources for its production. Therefore, this work analyzes the technical and environmental aspects of concrete with full replacement of natural aggregates for processed LD steelmaking slag. The experimental program comprehends physical characterization - particle size distribution, moisture content, bulk and specific density - and elemental chemical characterization with X-Ray Fluorescence, and mineralogical characterization via X-Ray Diffraction. Morphological characterization was performed through a stereomicroscope. From these results, concrete with compressive strengths of 20 and 40 Mpa were developed, with ABPC methodology. These were characterized in the fresh and hardened states, obtaining results favorable to the steelmaking slag application in Portland cement concrete. This sustainable concrete features properties similar conventional concrete, and contributing to sustainability of buildings. (author)

Phase separation in short-chain lecithin/gel-state long-chain lecithin aggregates

International Nuclear Information System (INIS)

Bian, J.; Roberts, M.F.

1990-01-01

Small bilayer particles for spontaneously from gel-state long-chain phospholipids such as dipalmitoylphosphatidylcholine and 0.2 mol fraction short-chain lecithins (e.g., diheptanoylphosphatidylcholine). When the particles are incubed at temperatures greater than the T m of the long-chain phosphatidylcholine (PC), the particles rapidly fuse (from 90-angstrom to ≥ 5,000-angstrom radius); this transition is reversible. A possible explanation for this behavior involves patching or phase separation of the short-chain component within the gel-state particle and randomization of both lipid species above T m . Differential scanning calorimetry, 1 H T 1 values of proteodiheptanoyl-PC in diheptanoyl-PC-d 26 /dipalmitoyl-PC-d 62 matrices of varying deuterium content, solid-state 2 H NMR spectroscopy as a function of temperature, and fluorescence pyrene excimer-to-monomer ratios as a function of mole fraction diheptanoyl-PC provide evidence that such phase separation must occur. These results are used to construct a phase diagram for the diheptanoyl-PC/dipalmitoyl-PC system, to propose detailed geometric models for the different lipid particles involved, and to understand phospholipase kinetics toward the different aggregates

Recycled aggregates in concrete production: engineering properties and environmental impact

OpenAIRE

Seddik Meddah Mohammed

2017-01-01

Recycled concrete aggregate is considered as the most abundant and used secondary aggregate in concrete production, other types of solid waste are also being used in concrete for specific purposes and to achieve some desired properties. Recycled aggregates and particularly, recycled concrete aggregate substantially affect the properties and mix design of concrete both at fresh and hardened states since it is known by high porosity due to the adhered layer of old mortar on the aggregate which ...

Observing Convective Aggregation

Science.gov (United States)

Holloway, Christopher E.; Wing, Allison A.; Bony, Sandrine; Muller, Caroline; Masunaga, Hirohiko; L'Ecuyer, Tristan S.; Turner, David D.; Zuidema, Paquita

2017-11-01

Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network.

Influence of limestone waste as partial replacement material for sand and marble powder in concrete properties

Directory of Open Access Journals (Sweden)

Omar M. Omar

2012-12-01

Full Text Available Green concrete are generally composed of recycling materials as hundred or partial percent substitutes for aggregate, cement, and admixture in concrete. Limestone waste is obtained as a by-product during the production of aggregates through the crushing process of rocks in rubble crusher units. Using quarry waste as a substitute of sand in construction materials would resolve the environmental problems caused by the large-scale depletion of the natural sources of river and mining sands. This paper reports the experimental study undertaken to investigate the influence of partial replacement of sand with limestone waste (LSW, with marble powder (M.P as an additive on the concrete properties. The replacement proportion of sand with limestone waste, 25%, 50%, and 75% were practiced in the concrete mixes except in the concrete mix. Besides, proportions of 5%, 10% and 15% marble powder were practiced in the concrete mixes. The effects of limestone waste as fine aggregate on several fresh and hardened properties of the concretes were investigated. The investigation included testing of compressive strength, indirect tensile strength, flexural strength, modulus of elasticity, and permeability. It was found that limestone waste as fine aggregate enhanced the slump test of the fresh concretes. But the unit weight concretes were not affected. However, the good performance was observed when limestone waste as fine aggregate was used in presence of marble powder.

Effects of surface roughness on plastic strain localization in polycrystalline aggregates

Directory of Open Access Journals (Sweden)

Guilhem Yoann

2014-06-01

Full Text Available The surface state of mechanical components differs according to applied loadings. Industrial processes may produce specific features at the surface, such as roughness, local hardening, residual stresses or recrystallization. Under fatigue loading, all these parameters will affect the component lifetime, but in different manner. A better understanding of each surface state parameter, separately first and then all combined, will provide a better prediction of fatigue life. The study focuses on the effect of surface roughness. Crystal plasticity finite element computations have been carried out on three-dimensional polycrystalline aggregates with different roughness levels. Local mechanical fields have been analyzed both at the surface and inside the bulk to highlight the competition between crystallography and roughness to impose localization patterns. As soon as surface roughness is strong enough, classical localization bands driven by grains orientation are replaced by localizations patterns driven by the local roughness topology. Nevertheless, this effect tends to decrease gradually under the surface, and it becomes usually negligible after the first layer of grains. The discussion allows us to characterize the influence of the surface state on the local mechanical fields.

Long-term deflection and flexural behavior of reinforced concrete beams with recycled aggregate

International Nuclear Information System (INIS)

Choi, Won-Chang; Yun, Hyun-Do

2013-01-01

Highlights: • Long-term deformation of recycled aggregate concrete beams was examined. • Three beams were monitored for over 380 days. • Influence of recycled aggregate on the long-term performance. • Comparison of that between normal and recycled aggregate concrete beams. - Abstract: This paper presents experimental results on the long-term deformations of recycled aggregate concrete (RAC) beams for over 1 year (380 days) and flexural behavior of RAC beams after exposure to sustained loading. Three reinforced concrete (RC) beam specimens were fabricated with replacement percentage of aggregate (100% natural aggregate, 100% recycled coarse aggregate, and 50% recycled fine aggregate) and subjected to sustained loading that is 50% of the nominal flexural capacity. During the sustained loading period (380 days), the long-term deflection due to creep and shrinkage was recorded and compared with predicted behavior that was determined based on current specifications (ACI 318 Code). After measuring the long-term deflection for 380 days, four-point bending tests were conducted to investigate the flexural behavior of RC beams after exposure to sustained loading and determine any reduction in flexural capacity. A modified equation to predict the long-term deflection values for RC beams with recycled aggregate is proposed, and the experimental results are compared with the predictions calculated using the ACI 318 Code provisions

Production of Controlled Low Strength Material Utilizing Waste Paper Sludge Ash and Recycled Aggregate Concrete

Directory of Open Access Journals (Sweden)

Azmi A. N.

2016-01-01

Full Text Available Recently, the best method to make the concrete industry more sustainable was using the waste materials to replace the natural resources. Currently waste paper sludge is a major economic and environmental problem in this country. In this research, the alternative method is to dwindle the usage of natural resources and the usage of cement in the construction. This method is to replace the usage of cement with the waste paper sludge ash (WPSA and to use the recycle aggregate collected from the construction is used. The WPSA has ingredient likely cement such as self-cementation but for a low strength. The research was conducted at heavy laboratory UITM Pulau Pinang. Meanwhile, the WPSA is collected at MNI Industries at Mentakab, Pahang. The recycle aggregate is a separated half, which were fine aggregate and the coarse aggregate with the specific size. In this research, the ratio is divided into two (2 which is 1:1 and 1:2 for the aggregate and difference percentage levels of WPSA. The percentage levels of WPSA that use in this research are 10%, 20%, 30%, 40%, 50%, and 60%. A total of 36 cubes were prepared. Aim of this research is to develop a simple design approach for the mixture proportioning of WPSA and recycle concrete aggregate (RCA within the concrete and to assess the effect of concrete mix with different percentage of WPSA and RCA ratio on the properties. It is found that the best design mix that achieves control low strength material (CLSM is on 30% of WPSA with the ratio 1:2 on day 28 of compression test.

Effects of Elevated Temperature on Concrete with Recycled Coarse Aggregates

Science.gov (United States)

Salau, M. A.; Oseafiana, O. J.; Oyegoke, T. O.

2015-11-01

This paper discusses the effects of heating temperatures of 200°C, 400°C and 600°C each for 2 hours at a heating rate of 2.5°C/min on concrete with the content of Natural Coarse Aggregates (NCA) partially replaced with Recycled Coarse Aggregates (RCA), obtained from demolished building in the ratio of 0%, 15% and 30%.There was an initial drop in strength from 100°C to 200°C which is suspected to be due to the relatively weak interfacial bond between the RCA and the hardened paste within the concrete matrix;a gradual increase in strength continued from 200°C to 450°C and steady drop occurred again as it approached 600°C.With replacement proportion of 0%, 15% and 30% of NCA and exposure to peak temperature of 600°C, a relative concrete strength of 23.6MPa, 25.3MPa and 22.2MPa respectively can be achieved for 28 days curing age. Furthermore, RAC with 15% NCA replacement when exposed to optimum temperature of 450°C yielded high compressive strength comparable to that of control specimen (normal concrete). In addition, for all concrete samples only slight surface hairline cracks were noticed as the temperature approached 400°C. Thus, the RAC demonstrated behavior just like normal concrete and may be considered fit for structural use.

Learning about individuals' health from aggregate data.

Science.gov (United States)

Colbaugh, Rich; Glass, Kristin

2017-07-01

There is growing awareness that user-generated social media content contains valuable health-related information and is more convenient to collect than typical health data. For example, Twitter has been employed to predict aggregate-level outcomes, such as regional rates of diabetes and child poverty, and to identify individual cases of depression and food poisoning. Models which make aggregate-level inferences can be induced from aggregate data, and consequently are straightforward to build. In contrast, learning models that produce individual-level (IL) predictions, which are more informative, usually requires a large number of difficult-to-acquire labeled IL examples. This paper presents a new machine learning method which achieves the best of both worlds, enabling IL models to be learned from aggregate labels. The algorithm makes predictions by combining unsupervised feature extraction, aggregate-based modeling, and optimal integration of aggregate-level and IL information. Two case studies illustrate how to learn health-relevant IL prediction models using only aggregate labels, and show that these models perform as well as state-of-the-art models trained on hundreds or thousands of labeled individuals.

Can one ``Hear'' the aggregation state of a granular system?

Science.gov (United States)

Kruelle, Christof A.; Sánchez, Almudena García

2013-06-01

If an ensemble of macroscopic particles is mechanically agitated the constant energy input is dissipated into the system by multiple inelastic collisions. As a result, the granular material can exhibit, depending on the magnitude of agitation, several physical states - like a gaseous phase for high energy input or a condensed state for low agitation. Here we introduce a new method for quantifying the acoustical response of the granular system. Our experimental system consists of a monodisperse packing of glass beads with a free upper surface, which is confined inside a cylindrical container. An electro-mechanical shaker exerts a sinusoidal vertical vibration at normalized accelerations well above the fluidization threshold for a monolayer of particles. By increasing the number of beads the granular gas suddenly collapses if a critical threshold is exceeded. The transition can be detected easily with a microphone connected to the soundcard of a PC. From the recorded audio track a FFT is calculated in real-time. Depending on either the number of particles at a fixed acceleration or the amount of energy input for a given number of particles, the resulting rattling noise exhibits a power spectrum with either the dominating (shaker) frequency plus higher harmonics for a granular crystal or a high-frequency broad-band noise for a granular gas, respectively. Our new method demonstrates that it is possible to quantify analytically the subjective audio impressions of a careful listener and thus to distinguish easily between different aggregation states of an excited granular system.

Behavior of the aggregate wind resource in the ISO regions in the United States

KAUST Repository

Gunturu, Udaya

2015-04-01

The collective behavior of wind farms in seven Independent System Operator (ISO) areas has been studied. The generation duration curves for each ISO show that there is no aggregated power for some fraction of time. Aggregation of wind turbines mitigates intermittency to some extent, but in each ISO there is considerable fraction of time when there is less than 5% capacity. The hourly wind power time series show benefit of aggregation but the high and low wind events are lumped in time, thus indicating that intermittency is synchronized in each region. The timeseries show that there are instances when there is no wind power in most ISOs because of large-scale high pressure systems. An analytical consideration of the collective behavior of aggregated wind turbines shows that the benefit of aggregation saturates beyond a certain number of generating units asymptotically. Also, the benefit of aggregation falls rapidly with temporal correlation between the generating units.

Behavior of the aggregate wind resource in the ISO regions in the United States

KAUST Repository

Gunturu, Udaya; Schlosser, Clemens Adam

2015-01-01

The collective behavior of wind farms in seven Independent System Operator (ISO) areas has been studied. The generation duration curves for each ISO show that there is no aggregated power for some fraction of time. Aggregation of wind turbines mitigates intermittency to some extent, but in each ISO there is considerable fraction of time when there is less than 5% capacity. The hourly wind power time series show benefit of aggregation but the high and low wind events are lumped in time, thus indicating that intermittency is synchronized in each region. The timeseries show that there are instances when there is no wind power in most ISOs because of large-scale high pressure systems. An analytical consideration of the collective behavior of aggregated wind turbines shows that the benefit of aggregation saturates beyond a certain number of generating units asymptotically. Also, the benefit of aggregation falls rapidly with temporal correlation between the generating units.

Effects of Uncrushed Aggregate on the Mechanical Properties of No-Fines Concrete

Directory of Open Access Journals (Sweden)

M. A. Memon

2018-06-01

Full Text Available Concrete’s self-weight is a major aspect of a structure’s overall weight. Recently, the use of lightweight concrete (no-fines, foamed and cellular concrete has been increased. Normally no-fines concrete is produced with crushed coarse aggregate of uniform gradation. This study aims to investigate experimentally the effects of the use of uncrushed coarse aggregates on unit weight, compressive and tensile strength of the no-fines (NFC as well as conventional concrete (CC. In addition, the effects of coarse aggregate size on the mechanical properties were also studied. Four gradations of uncrushed coarse aggregates ranging between (5.5-4.75 mm, (10-4.75 mm, (20-4.75 mm and (25-4.75 mm were used for preparing the concretes. The fixed cement-aggregate ratios of 1:6 (with w/c ratio=0.4 and 1:2:4 (with w/c ratio=0.5 were adopted for NFC and CC respectively. It was found that the gradation of uncrushed coarse aggregate has a significant effect on the mechanical properties of NFC. A maximum of 16% reduction in self-weight of the concrete without fines was obtained, as compared to that with fines. Moreover, the compressive strength of no-fines concrete significantly improved by replacing crushed with uncrushed coarse aggregate. The compressive strength increased by 16% for the batch of (25-4.75 mm.

Effect of protein-surfactant interactions on aggregation of β-lactoglobulin.

Science.gov (United States)

Hansted, Jon G; Wejse, Peter L; Bertelsen, Hans; Otzen, Daniel E

2011-05-01

The milk protein β-lactoglobulin (βLG) dominates the properties of whey aggregates in food products. Here we use spectroscopic and calorimetric techniques to elucidate how anionic, cationic and non-ionic surfactants interact with bovine βLG and modulate its heat-induced aggregation. Alkyl trimethyl ammonium chlorides (xTAC) strongly promote aggregation, while sodium alkyl sulfates (SxS) and alkyl maltopyranosides (xM) reduce aggregation. Sodium dodecyl sulfate (SDS) binds to non-aggregated βLG in several steps, but reduction of aggregation was associated with the first binding step, which occurs far below the critical micelle concentration. In contrast, micellar concentrations of xMs are required to reduce aggregation. The ranking order for reduction of aggregation (normalized to their tendency to self-associate) was C10-C12>C8>C14 for SxS and C8>C10>C12>C14>C16 for xM. xTAC promote aggregation in the same ranking order as xM reduce it. We conclude that SxS reduce aggregation by stabilizing the protein's ligand-bound state (the melting temperature t(m) increases by up to 10°C) and altering its charge potential. xM monomers also stabilize the protein's ligand-bound state (increasing t(m) up to 6°C) but in the absence of charged head groups this is not sufficient by itself to prevent aggregation. Although micelles of both anionic and non-ionic surfactants destabilize βLG, they also solubilize unfolded protein monomers, leaving them unavailable for protein-protein association and thus inhibiting aggregation. Cationic surfactants promote aggregation by a combination of destabilization and charge neutralization. The food compatible surfactant sodium dodecanoate also inhibited aggregation well below the cmc, suggesting that surfactants may be a practical way to modulate whey protein properties. Copyright © 2011 Elsevier B.V. All rights reserved.

Compressive Strength and Modulus of Elasticity of Concrete with Cubed Waste Tire Rubbers as Coarse Aggregates

Science.gov (United States)

Haryanto, Y.; Hermanto, N. I. S.; Pamudji, G.; Wardana, K. P.

2017-11-01

One feasible solution to overcome the issue of tire disposal waste is the use of waste tire rubber to replace aggregate in concrete. We have conducted an experimental investigation on the effect of rubber tire waste aggregate in cuboid form on the compressive strength and modulus of elasticity of concrete. The test was performed on 72 cylindrical specimens with the height of 300 mm and diameter of 150 mm. We found that the workability of concrete with waste tire rubber aggregate has increased. The concrete density with waste tire rubber aggregate was decreased, and so was the compressive strength. The decrease of compressive strength is up to 64.34%. If the content of waste tire rubber aggregate is more than 40%, then the resulting concrete cannot be categorized as structural concrete. The modulus of elasticity decreased to 59.77%. The theoretical equation developed to determine the modulus of elasticity of concrete with rubber tire waste aggregate has an accuracy of 84.27%.

J-aggregation, its impact on excited state dynamics and unique solvent effects on macroscopic assembly of a core-substituted naphthalenediimide

KAUST Repository

Kar, Haridas; Gehrig, Dominik W.; Laquai, Fré dé ric; Ghosh, Suhrit

2015-01-01

Herein we reveal a straightforward supramolecular design for the H-bonding driven J-aggregation of an amine-substituted cNDI in aliphatic hydrocarbons. Transient absorption spectroscopy reveals sub-ps intramolecular electron transfer in isolated NDI molecules in a THF solution followed by a fast recombination process, while a remarkable extension of the excited state lifetime by more than one order of magnitude occurred in methylcyclohexane likely owing to an increased charge-separation as a result of better delocalization of the charge-separated states in J-aggregates. We also describe unique solvent-effects on the macroscopic structure and morphology. While J-aggregation with similar photophysical characteristics was noticed in all the tested aliphatic hydrocarbons, the morphology strongly depends on the “structure” of the solvents. In linear hydrocarbons (n-hexane, n-octane, n-decane or n-dodecane), formation of an entangled fibrillar network leads to macroscopic gelation while in cyclic hydrocarbons (methylcyclohexane or cyclohexane) although having a similar polarity, the cNDI exhibits nanoscale spherical particles. These unprecedented solvent effects were rationalized by establishing structure-dependent specific interactions of the solvent molecules with the cNDI which may serve as a general guideline for solvent-induced morphology-control of structurally related self-assembled materials.

J-aggregation, its impact on excited state dynamics and unique solvent effects on macroscopic assembly of a core-substituted naphthalenediimide

KAUST Repository

Kar, Haridas

2015-03-12

Herein we reveal a straightforward supramolecular design for the H-bonding driven J-aggregation of an amine-substituted cNDI in aliphatic hydrocarbons. Transient absorption spectroscopy reveals sub-ps intramolecular electron transfer in isolated NDI molecules in a THF solution followed by a fast recombination process, while a remarkable extension of the excited state lifetime by more than one order of magnitude occurred in methylcyclohexane likely owing to an increased charge-separation as a result of better delocalization of the charge-separated states in J-aggregates. We also describe unique solvent-effects on the macroscopic structure and morphology. While J-aggregation with similar photophysical characteristics was noticed in all the tested aliphatic hydrocarbons, the morphology strongly depends on the “structure” of the solvents. In linear hydrocarbons (n-hexane, n-octane, n-decane or n-dodecane), formation of an entangled fibrillar network leads to macroscopic gelation while in cyclic hydrocarbons (methylcyclohexane or cyclohexane) although having a similar polarity, the cNDI exhibits nanoscale spherical particles. These unprecedented solvent effects were rationalized by establishing structure-dependent specific interactions of the solvent molecules with the cNDI which may serve as a general guideline for solvent-induced morphology-control of structurally related self-assembled materials.

Evaluation of Different Mineral Filler Aggregates for Asphalt Mixtures

Science.gov (United States)

Wasilewska, Marta; Małaszkiewicz, Dorota; Ignatiuk, Natalia

2017-10-01

Mineral filler aggregates play an important role in asphalt mixtures because they fill voids in paving mix and improve the cohesion of asphalt binder. Limestone powder containing over 90% of CaCO3 is the most frequently used type of filler. Waste material from the production of coarse aggregate can be successfully used as a mineral filler aggregate for hot asphalt concrete mixtures as the limestone powder replacement. This paper presents the experimental results of selected properties of filler aggregates which were obtained from rocks with different mineral composition and origin. Five types of rocks were used as a source of the mineral filler aggregate: granite, gabbro, trachybasalt, quartz sandstone and rocks from postglacial deposits. Limestone filler was used in this study as the reference material. The following tests were performed: grading (air jet sieving), quality of fines according to methylene blue test, water content by drying in a ventilated oven, particle density using pyknometer method, Delta ring and ball test, Bitumen Number, fineness determined as Blaine specific surface area. Mineral filler aggregates showed significant differences when they were mixed with bitumen and stiffening effect in Delta ring and ball test was evaluated. The highest values were achieved when gabbro and granite fillers were used. Additionally, Scanning Electron Microscopy (SEM) analysis of grain shape and size was carried out. Significant differences in grain size and shape were observed. The highest non-homogeneity in size was determined for quartz sandstone, gabbro and granite filler. Their Blaine specific surface area was lower than 2800 cm2/g, while for limestone and postglacial fillers with regular and round grains it exceeded 3000 cm2/g. All examined mineral filler aggregates met requirements of Polish National Specification WT-1: 2014 and could be used in asphalt mixtures.

Feasibility of reclaimed asphalt pavement as aggregate in portland cement concrete pavement, phase II : field demonstration.

Science.gov (United States)

2015-10-01

This research was focused on evaluating the feasibility of using minimally processed reclaimed asphalt pavement (RAP) as : aggregate replacement in concrete pavements. An initial phase of research demonstrated that concretes with up to 50 percent : o...

Platelet aggregation and quality control of platelet concentrates produced in the Amazon Blood Bank

Directory of Open Access Journals (Sweden)

Maria José Dantas Coêlho

2011-01-01

Full Text Available BACKGROUND: The study of platelet aggregation is essential to assess in vitro platelet function by different platelet activation pathways. OBJECTIVE: To assess aggregation and biochemical parameters of random platelet concentrates produced at the Fundação HEMOAM using the quality control tests defined by law. METHODS: Whole blood samples from 80 donors and the respective platelet concentrate units were tested. Platelet concentrates were tested (platelet count, aggregation and pH on days 1, 3 and 5 of storage. Additionally a leukocyte count was done only on day 1 and microbiological tests on day 5 of storage. Collagen and adenosine diphosphate were used as inducing agonists for platelet aggregation testing. RESULTS: Donor whole blood had normal aggregation (aggregation with adenosine diphosphate = 67% and with collagen = 78%. The median aggregation in platelet concentrates with adenosine diphosphate was low throughout storage (18% on day 1, 7% on day 3 and 6% on day 5 and the median aggregation with collagen was normal only on day 1 and low thereafter (54.4% on day 1, 20.5% on day 3 and 9% on day 5. CONCLUSION: Although the results were within the norms required by law, platelet concentrates had low aggregation rates. We suggest the inclusion of a functional assessment test for the quality control of platelet concentrates for a more effective response to platelet replacement therapy.

Stripping in hot mix asphalt produced by aggregates from construction and demolition waste.

Science.gov (United States)

Pérez, I; Pasandín, A R; Gallego, J

2012-01-01

This paper analyses the effect of water on the durability of hot asphalt mixtures made with recycled aggregates from construction and demolition debris. Indirect tensile stress tests were carried out to evaluate stripping behaviour. The mixtures tested were fabricated with 0, 20, 40 and 60% recycled aggregates. Two types of natural aggregates were used: schist and calcite dolomite. An increase in the percentage of recycled aggregates was found to produce a decrease in the tensile stress ratio of the hot asphalt mixtures. To study this phenomenon, two and three factor analyses of variance (ANOVA) were performed with indirect tensile stress being used as the dependent variable. The factors studied were the percentage of recycled aggregates (0, 20, 40 and 60%), the moisture state (dry, wet) and the type of natural aggregate (schist, calcite). On the basis of the ANOVA results, it was found that the most important factor affecting resistance was the moisture state (dry, wet) of the specimens. The percentage of recycled aggregate also affected indirect tensile stress, especially in the dry state. The type of natural aggregate did not have a significant effect on indirect tensile stress. The hot asphalt mixture specimens made with different percentages of recycled aggregates from construction and demolition debris and of natural quarry aggregates showed poor stripping behaviour. This stripping behaviour can be related to both the poor adhesion of the recycled aggregates and the high absorption of the mortar of cement adhered to them.

Aggregating Local Descriptors for Epigraphs Recognition

OpenAIRE

Amato, Giuseppe; Falchi, Fabrizio; Rabitti, Fausto; Vadicamo, Lucia

2014-01-01

In this paper, we consider the task of recognizing epigraphs in images such as photos taken using mobile devices. Given a set of 17,155 photos related to 14,560 epigraphs, we used a k-NearestNeighbor approach in order to perform the recognition. The contribution of this work is in evaluating state-of-the-art visual object recognition techniques in this specific context. The experimental results conducted show that Vector of Locally Aggregated Descriptors obtained aggregating SIFT descriptors ...

Study on the durability of concrete using granulated blast furnace slag as fine aggregate

Science.gov (United States)

Shi, Dongsheng; Liu, Qiang; Xue, Xinxin; He, Peiyuan

2018-03-01

In order to assessing the durability of concrete using granulated blastfurnace slag (GBS) as fine aggregate and compare it with natural river sand concrete, three different size of specimen were produced by using the same mix proportion with 3 different water cement ratios and 3 replacement ratios, and using it to measure the three aspects on the durability of concrete including freeze-thaw performance, dry-shrinkage performance and anti-chloride-permeability performance. In this paper. The test results show that using GBS as fine aggregate can slightly improve anti-chloride-permeability performance and dry-shrinkage performance of concrete in the condition of low water cement ratio, on the other hand, using GBS or natural river sand as fine aggregate has almost similar durability of concrete.

Performance of composite sand cement brick containing recycle concrete aggregate and waste polyethylene terephthalate with different mix design ratio

Science.gov (United States)

Azmi, N. B.; Khalid, F. S.; Irwan, J. M.; Mazenan, P. N.; Zahir, Z.; Shahidan, S.

2018-04-01

This study is focuses to the performance of composite sand cement brick containing recycle concrete aggregate and waste polyethylene terephthalate. The objective is to determine the mechanical properties such as compressive strength and water absorption of composite brick containing recycled concrete aggregate and polyethylene terephthalate waste and to determine the optimum mix ratio of bricks containing recycled concrete aggregate and polyethylene terephthalate waste. The bricks specimens were prepared by using 100% natural sand, they were then replaced by RCA at 25%, 50% and 75% with proportions of PET consists of 1.0%, 1.5%, 2.0% and 2.5% by weight of natural sand. Based on the results of compressive strength, it indicates that the replacement of RCA shows an increasing strength as the strength starts to increase from 25% to 50% for both mix design ratio. The strength for RCA 75% volume of replacement started to decrease as the volume of PET increase. However, the result of water absorption with 50% RCA and 1.0% PET show less permeable compared to control brick at both mix design ratio. Thus, one would expect the density of brick decrease and the water absorption to increase as the RCA and PET content is increased.

Evaluation of recycled concrete as aggregate in new concrete pavements.

Science.gov (United States)

2014-04-01

This study evaluated the use of recycled concrete as coarse aggregate in new concrete pavements. : Recycled concrete aggregate (RCA) produced from demolished pavements in three geographically dispersed locations in Washington state were used to perfo...

Monitoring the Aggregation of Dansyl Chloride in Acetone through Fluorescence Measurements

Institute of Scientific and Technical Information of China (English)

FANG，Yu; YIN，Yi－Qing; 等

2002-01-01

The aggregation of dansyl chloride (DNS-Cl) in acetone has been studied in detail by steady-state fluorescence techniques.It has been demonstrated that DNS-Cl is stable in acetone during purification and aggregation study processes.The aggregates are not solvolyzed in acetone,and do not take part n any chemical reactions either.It has been found that DNS-Cl tends to aggregate even when its concentration is much lower than its solubility in acetone.The aggregation is reversible,and both the aggregation and the deaggregation are very slow processes.Introduction of SDS has a positive effect upon the formation and stabilization of the aggregates.

Monitoring the Aggregation of Dansyl Chloride in Acetone through Fluorescence Measurements

Institute of Scientific and Technical Information of China (English)

FANG,Yu(房喻); YIN,Yi-Qing(尹艺青); HU,Dao-Dao(胡道道); GAO,Gai-Ling(高改玲)

2002-01-01

The aggregation of dansyl chloride (DNS-Cl) in acetone has been studied in detail by steady-state fluorescence techniques. It has been demonstrated that DNS-Cl is stable in acetone during purification and aggregation study processes. The aggregates are not solvolyzed in acetone, and do not take part in any chemical reactions either. It has been found that DNS-Cl tends to aggregate even when its concentration is much lower than its solubility in acetone. The aggregation is reversible, and both the aggregation and the deaggregation are very slow processes.Introduction of SDS has a positive effect upon the formation and stabilization of the aggregates.

State-of-the-Art Report on Fiber-Reinforced Lightweight Aggregate Concrete Masonry

Directory of Open Access Journals (Sweden)

Saul Rico

2017-01-01

Full Text Available Masonry construction is the most widely used building method in the world. Concrete masonry is relatively low in cost due to the vast availability of aggregates used within the production process. These aggregate materials are not always reliable for structural use. One of the principal issues associated with masonry is the brittleness of the unit. When subject to seismic loads, the brittleness of the masonry magnifies. In regions with high seismic activity and unspecified building codes or standards, masonry housing has developed into a death trap for countless individuals. A common approach concerning the issue associated with the brittle characteristic of masonry is addition of steel reinforcement. However, this can be expensive, highly dependent on skillfulness of labor, and particularly dependent on the quality of available steel. A proposed solution presented in this investigation consists of introducing steel fibers to the lightweight aggregate concrete masonry mix. Previous investigations in the field of lightweight aggregate fiber-reinforced concrete have shown an increase in flexural strength, toughness, and ductility. The outcome of this research project provides invaluable data for the production of a ductile masonry unit capable of withstanding seismic loads for prolonged periods.

Chemical-mineralogical characterisation of coarse recycled concrete aggregate

International Nuclear Information System (INIS)

Limbachiya, M.C.; Marrocchino, E.; Koulouris, A.

2007-01-01

The construction industry is now putting greater emphasis than ever before on increasing recycling and promoting more sustainable waste management practices. In keeping with this approach, many sectors of the industry have actively sought to encourage the use of recycled concrete aggregate (RCA) as an alternative to primary aggregates in concrete production. The results of a laboratory experimental programme aimed at establishing chemical and mineralogical characteristics of coarse RCA and its likely influence on concrete performance are reported in this paper. Commercially produced coarse RCA and natural aggregates (16-4 mm size fraction) were tested. Results of X-ray fluorescence (XRF) analyses showed that original source of RCA had a negligible effect on the major elements and a comparable chemical composition between recycled and natural aggregates. X-ray diffraction (XRD) analyses results indicated the presence of calcite, portlandite and minor peaks of muscovite/illite in recycled aggregates, although they were directly proportioned to their original composition. The influence of 30%, 50%, and 100% coarse RCA on the chemical composition of equal design strength concrete has been established, and its suitability for use in a concrete application has been assessed. In this work, coarse RCA was used as a direct replacement for natural gravel in concrete production. Test results indicated that up to 30% coarse RCA had no effect on the main three oxides (SiO 2 , Al 2 O 3 and CaO) of concrete, but thereafter there was a marginal decrease in SiO 2 and increase in Al 2 O 3 and CaO contents with increase in RCA content in the mix, reflecting the original constituent's composition

Chemical-mineralogical characterisation of coarse recycled concrete aggregate.

Science.gov (United States)

Limbachiya, M C; Marrocchino, E; Koulouris, A

2007-01-01

The construction industry is now putting greater emphasis than ever before on increasing recycling and promoting more sustainable waste management practices. In keeping with this approach, many sectors of the industry have actively sought to encourage the use of recycled concrete aggregate (RCA) as an alternative to primary aggregates in concrete production. The results of a laboratory experimental programme aimed at establishing chemical and mineralogical characteristics of coarse RCA and its likely influence on concrete performance are reported in this paper. Commercially produced coarse RCA and natural aggregates (16-4 mm size fraction) were tested. Results of X-ray fluorescence (XRF) analyses showed that original source of RCA had a negligible effect on the major elements and a comparable chemical composition between recycled and natural aggregates. X-ray diffraction (XRD) analyses results indicated the presence of calcite, portlandite and minor peaks of muscovite/illite in recycled aggregates, although they were directly proportioned to their original composition. The influence of 30%, 50%, and 100% coarse RCA on the chemical composition of equal design strength concrete has been established, and its suitability for use in a concrete application has been assessed. In this work, coarse RCA was used as a direct replacement for natural gravel in concrete production. Test results indicated that up to 30% coarse RCA had no effect on the main three oxides (SiO2, Al2O3 and CaO) of concrete, but thereafter there was a marginal decrease in SiO2 and increase in Al2O3 and CaO contents with increase in RCA content in the mix, reflecting the original constituent's composition.

Signature of an aggregation-prone conformation of tau

Science.gov (United States)

Eschmann, Neil A.; Georgieva, Elka R.; Ganguly, Pritam; Borbat, Peter P.; Rappaport, Maxime D.; Akdogan, Yasar; Freed, Jack H.; Shea, Joan-Emma; Han, Songi

2017-03-01

The self-assembly of the microtubule associated tau protein into fibrillar cell inclusions is linked to a number of devastating neurodegenerative disorders collectively known as tauopathies. The mechanism by which tau self-assembles into pathological entities is a matter of much debate, largely due to the lack of direct experimental insights into the earliest stages of aggregation. We present pulsed double electron-electron resonance measurements of two key fibril-forming regions of tau, PHF6 and PHF6*, in transient as aggregation happens. By monitoring the end-to-end distance distribution of these segments as a function of aggregation time, we show that the PHF6(*) regions dramatically extend to distances commensurate with extended β-strand structures within the earliest stages of aggregation, well before fibril formation. Combined with simulations, our experiments show that the extended β-strand conformational state of PHF6(*) is readily populated under aggregating conditions, constituting a defining signature of aggregation-prone tau, and as such, a possible target for therapeutic interventions.

Markov chain aggregation and its applications to combinatorial reaction networks.

Science.gov (United States)

Ganguly, Arnab; Petrov, Tatjana; Koeppl, Heinz

2014-09-01

We consider a continuous-time Markov chain (CTMC) whose state space is partitioned into aggregates, and each aggregate is assigned a probability measure. A sufficient condition for defining a CTMC over the aggregates is presented as a variant of weak lumpability, which also characterizes that the measure over the original process can be recovered from that of the aggregated one. We show how the applicability of de-aggregation depends on the initial distribution. The application section is devoted to illustrate how the developed theory aids in reducing CTMC models of biochemical systems particularly in connection to protein-protein interactions. We assume that the model is written by a biologist in form of site-graph-rewrite rules. Site-graph-rewrite rules compactly express that, often, only a local context of a protein (instead of a full molecular species) needs to be in a certain configuration in order to trigger a reaction event. This observation leads to suitable aggregate Markov chains with smaller state spaces, thereby providing sufficient reduction in computational complexity. This is further exemplified in two case studies: simple unbounded polymerization and early EGFR/insulin crosstalk.

Recovery of MSWI and soil washing residues as concrete aggregates.

Science.gov (United States)

Sorlini, Sabrina; Abbà, Alessandro; Collivignarelli, Carlo

2011-02-01

The aim of the present work was to study if municipal solid waste incinerator (MSWI) residues and aggregates derived from contaminated soil washing could be used as alternative aggregates for concrete production. Initially, chemical, physical and geometric characteristics (according to UNI EN 12620) of municipal solid waste incineration bottom ashes and some contaminated soils were evaluated; moreover, the pollutants release was evaluated by means of leaching tests. The results showed that the reuse of pre-treated MSWI bottom ash and washed soil is possible, either from technical or environmental point of view, while it is not possible for the raw wastes. Then, the natural aggregate was partially and totally replaced with these recycled aggregates for the production of concrete mixtures that were characterized by conventional mechanical and leaching tests. Good results were obtained using the same dosage of a high resistance cement (42.5R calcareous Portland cement instead of 32.5R); the concrete mixture containing 400 kg/m(3) of washed bottom ash and high resistance cement was classified as structural concrete (C25/30 class). Regarding the pollutants leaching, all concrete mixtures respected the limit values according to the Italian regulation. Copyright © 2010 Elsevier Ltd. All rights reserved.

DURABILITY OF GREEN CONCRETE WITH TERNARY CEMENTITIOUS SYSTEM CONTAINING RECYCLED AGGREGATE CONCRETE AND TIRE RUBBER WASTES

Directory of Open Access Journals (Sweden)

MAJID MATOUQ ASSAS

2016-06-01

Full Text Available All over the world billions of tires are being discarded and buried representing a serious ecological threat. Up to now a small part is recycled and millions of tires are just stockpiled, landfilled or buried. This paper presents results about the properties and the durability of green concrete contains recycled concrete as a coarse aggregate with partial replacement of sand by tire rubber wastes for pavement use. Ternary cementious system, Silica fume, Fly ash and Cement Kiln Dust are used as partial replacement of cement by weight. Each one replaced 10% of cement weight to give a total replacement of 30%. The durability performance was assessed by means of water absorption, chloride ion permeability at 28 and 90 days, and resistance to sulphuric acid attack at 1, 7, 14 and 28 days. Also to the compression behaviors for the tested specimens at 7, 14, 28 and 90 days were detected. The results show the existence of ternary cementitious system, silica fly ash and Cement Kiln Dust minimizes the strength loss associated to the use of rubber waste. In this way, up to 10% rubber content and 30% ternary cementious system an adequate strength class value (30 MPa, as required for a wide range of common structural uses, can be reached both through natural aggregate concrete and recycled aggregate concrete. Results also show that, it is possible to use rubber waste up to 15% and still maintain a high resistance to acid attack. The mixes with 10%silica fume, 10% fly ash and 10% Cement Kiln Dust show a higher resistance to sulphuric acid attack than the reference mix independently of the rubber waste content. The mixes with rubber waste and ternary cementious system was a lower resistance to sulphuric acid attack than the reference mix.

Aggregation patterns from nonlocal interactions: Discrete stochastic and continuum modeling

KAUST Repository

Hackett-Jones, Emily J.

2012-04-17

Conservation equations governed by a nonlocal interaction potential generate aggregates from an initial uniform distribution of particles. We address the evolution and formation of these aggregating steady states when the interaction potential has both attractive and repulsive singularities. Currently, no existence theory for such potentials is available. We develop and compare two complementary solution methods, a continuous pseudoinverse method and a discrete stochastic lattice approach, and formally show a connection between the two. Interesting aggregation patterns involving multiple peaks for a simple doubly singular attractive-repulsive potential are determined. For a swarming Morse potential, characteristic slow-fast dynamics in the scaled inverse energy is observed in the evolution to steady state in both the continuous and discrete approaches. The discrete approach is found to be remarkably robust to modifications in movement rules, related to the potential function. The comparable evolution dynamics and steady states of the discrete model with the continuum model suggest that the discrete stochastic approach is a promising way of probing aggregation patterns arising from two- and three-dimensional nonlocal interaction conservation equations. © 2012 American Physical Society.

Co-existence of free and self-trapped excitons in J-aggregates

International Nuclear Information System (INIS)

Malyukin, Yu.V.; Lebedenko, A.N.; Sorokin, A.V.; Yefimova, S.L.

2005-01-01

Nature of excited electronic states of amphi-PIC J-aggregates, which are the source of the self-trapping states, have been investigated using low-temperature site-selective, time-resolved spectroscopy techniques. The self-trapping states are shown to evolve from the delocalized exciton states within the J-band. The strongly localized electronic states located on the low-frequency edge of the J-band, are not able to form polaronic states and, hence, the polaronic relaxation process is particularly collective one. The exciton self-trapping is more effective in J-aggregates with strong disorder, requires overcoming a self-trapping barrier

Halogenated salicylaldehyde azines: The heavy atom effect on aggregation-induced emission enhancement properties

International Nuclear Information System (INIS)

Chen, Xiao-tong; Tong, Ai-jun

2014-01-01

This study investigates the heavy-atom effect (HAE) on aggregation-induced emission enhancement (AIEE) properties of salicylaldehyde azines. For this purpose, a series of halogenated salicylaldehyde azine derivatives, namely, chloro-salicylaldehyde azine (1), bromo-salicylaldehyde azine (2) and iodo-salicylaldehyde azine (3) are synthesized. 1 and 2 display typical AIEE characteristics of salicylaldehyde azine compounds; whereas for the iodo-substituent in 3, is found to be effective “external” heavy atom quenchers to salicylaldehyde azine fluorescence in aggregated state. Based on its weak fluorescence in aggregated state and relative strong fluorescence in dispersed state, 3 can also be applied as a turn-on fluorescence probe for egg albumin detection attributed to hydrophobic interaction. -- Highlights: • This study investigates the heavy-atom effect (HAE) on aggregation-induced emission enhancement (AIEE) properties of salicylaldehyde azines. • Chloro- and bromo-salicylaldehyde display typical AIEE properties of salicylaldehyde azine, whereas the iodo-substitute quenches AIEE in aggregated state. • Iodo-salicylaldehyde can be applied as a turn-on fluorescence probe for egg albumin detection attributed to hydrophobic interaction

Welfare State Replacements: Deinstitutionalization, Privatization and the Outsourcing to Immigrant Women Enterprise.

Science.gov (United States)

Nazareno, Jennifer

2018-04-01

The U.S. government has a long tradition of providing direct care services to many of its most vulnerable citizens through market-based solutions and subsidized private entities. The privatized welfare state has led to the continued displacement of some of our most disenfranchised groups in need of long-term care. Situated after the U.S. deinstitutionalization era, this is the first study to examine how immigrant Filipino women emerged as owners of de facto mental health care facilities that cater to the displaced, impoverished, severely mentally ill population. These immigrant women-owned businesses serve as welfare state replacements, overseeing the health and illness of these individuals by providing housing, custodial care, and medical services after the massive closure of state mental hospitals that occurred between 1955 and 1980. This study explains the onset of these businesses and the challenges that one immigrant group faces as owners, the meanings of care associated with their de facto mental health care enterprises, and the conditions under which they have operated for more than 40 years.

Solid-State Dewetting of Gold Aggregates/Islands on TiO2 Nanorod Structures Grown by Oblique Angle Deposition.

Science.gov (United States)

Liu, Shizhao; Plawsky, Joel L

2017-12-12

A composite film made of a stable gold nanoparticle (NP) array with well-controlled separation and size atop a TiO 2 nanorod film was fabricated via the oblique angle deposition (OAD) technique. The fabrication of the NP array is based on controlled, Rayleigh-instability-induced, solid-state dewetting of as-deposited gold aggregates on the TiO 2 nanorods. It was found that the initial spacing between as-deposited gold aggregates along the vapor flux direction should be greater than the TiO 2 interrod spacing created by 80° OAD to control dewetting and produce NP arrays. A numerical investigation of the process was conducted using a phase-field modeling approach. Simulation results showed that coalescence between neighboring gold aggregates is likely to have caused the uncontrolled dewetting in the 80° deposition, and this could be circumvented if the initial spacing between gold aggregates is larger than a critical value s min . We also found that TiO 2 nanorod tips affect dewetting dynamics differently than planar TiO 2 . The topology of the tips can induce contact line pinning and an increase in the contact angle along the vapor flux direction to the supported gold aggregates. These two effects are beneficial for the fabrication of monodisperse NPs based on Rayleigh-instability-governed self-assembly of materials, as they help to circumvent the undesired coalescence and facilitate the instability growth on the supported material. The findings uncover the application potential of OAD as a new method to fabricate structured films as template substrates to mediate dewetting. The reported composite films would have uses in optical coatings and photocatalytic systems, taking advantage of their ability to combine plasmonic nanostructures within a nanostructured dielectric film.

Replacing penalties

Directory of Open Access Journals (Sweden)

Vitaly Stepashin

2017-01-01

Full Text Available УДК 343.24The subject. The article deals with the problem of the use of "substitute" penalties.The purpose of the article is to identify criminal and legal criteria for: selecting the replacement punishment; proportionality replacement leave punishment to others (the formalization of replacement; actually increasing the punishment (worsening of legal situation of the convicted.Methodology.The author uses the method of analysis and synthesis, formal legal method.Results. Replacing the punishment more severe as a result of malicious evasion from serving accused designated penalty requires the optimization of the following areas: 1 the selection of a substitute punishment; 2 replacement of proportionality is serving a sentence other (formalization of replacement; 3 ensuring the actual toughening penalties (deterioration of the legal status of the convict. It is important that the first two requirements pro-vide savings of repression in the implementation of the replacement of one form of punishment to others.Replacement of punishment on their own do not have any specifics. However, it is necessary to compare them with the contents of the punishment, which the convict from serving maliciously evaded. First, substitute the punishment should assume a more significant range of restrictions and deprivation of certain rights of the convict. Second, the perfor-mance characteristics of order substitute the punishment should assume guarantee imple-mentation of the new measures.With regard to replacing all forms of punishment are set significant limitations in the application that, in some cases, eliminates the possibility of replacement of the sentence, from serving where there has been willful evasion, a stricter measure of state coercion. It is important in the context of the topic and the possibility of a sentence of imprisonment as a substitute punishment in cases where the original purpose of the strict measures excluded. It is noteworthy that the

Convective aggregation in realistic convective-scale simulations

OpenAIRE

Holloway, Christopher E.

2017-01-01

To investigate the real-world relevance of idealized-model convective self-aggregation, five 15-day cases of real organized convection in the tropics are simulated. These include multiple simulations of each case to test sensitivities of the convective organization and mean states to interactive radiation, interactive surface fluxes, and evaporation of rain. These simulations are compared to self-aggregation seen in the same model configured to run in idealized radiative-convective equilibriu...

The effect of bond characteristics between steel slag fine aggregate and cement paste on mechanical properties of concrete and mortar

International Nuclear Information System (INIS)

Yuji, W.

1988-01-01

The ordinary fine aggregate in concrete has been replaced by ground and sieved steel slag fine aggregate, treated and exposed to air for three months. Compared with concrete made from natural sand, properties such as compressive strength, flexural strength, elastic modules, permeability and abrasion resistance are considerably improved. The improvement increases with a decrease in w/c ratio, an increase in curing time and an increase in the replacement weight of sand. These results are due to the fact that the steel slag contains some active minerals such as C/sub 3/S, C/sub 2/S, C/sub 4/AF, etc., and shows favorable surface physical characteristics that improve the bond between steel slag particles and cement paste. The results of XRD, SEM and EPM microhardness showed that there are heavier concentration of ions, with finer crystals and a lower degree of CH orientation at the interfacial zone between steel slag particles and cement paste. The study also found small cementitious and fibrous C-S-H crystals growing from the fine aggregate, which are linked with hydrated products form cement paste making the bond and structural characteristic more favorable with cement. The steel slag fine aggregate is an active mineral similar to cement. The bond between the aggregate and cement paste is strengthened both physically and chemically

The maximum percentage of fly ash to replace part of original Portland cement (OPC) in producing high strength concrete

Science.gov (United States)

Mallisa, Harun; Turuallo, Gidion

2017-11-01

This research investigates the maximum percent of fly ash to replace part of Orginal Portland Cement (OPC) in producing high strength concrete. Many researchers have found that the incorporation of industrial by-products such as fly ash as in producing concrete can improve properties in both fresh and hardened state of concrete. The water-binder ratio was used 0.30. The used sand was medium sand with the maximum size of coarse aggregate was 20 mm. The cement was Type I, which was Bosowa Cement produced by PT Bosowa. The percentages of fly ash to the total of a binder, which were used in this research, were 0, 10, 15, 20, 25 and 30%; while the super platicizer used was typed Naptha 511P. The results showed that the replacement cement up to 25 % of the total weight of binder resulted compressive strength higher than the minimum strength at one day of high-strength concrete.

Trends in Testosterone Replacement Therapy Use from 2003 to 2013 among Reproductive-Age Men in the United States.

Science.gov (United States)

Rao, Pravin Kumar; Boulet, Sheree L; Mehta, Akanksha; Hotaling, James; Eisenberg, Michael L; Honig, Stanton C; Warner, Lee; Kissin, Dmitry M; Nangia, Ajay K; Ross, Lawrence S

2017-04-01

Although testosterone replacement therapy use in the United States has increased dramatically in the last decade, to our knowledge trends in testosterone replacement therapy use among reproductive-age men have not been investigated. We assessed changes in testosterone replacement therapy use and practice patterns among 18 to 45-year-old American men from 2003 to 2013 and compared them to older men. This is a retrospective, cross-sectional analysis of men 18 to 45 and 56 to 64 years old who were enrolled in the Truven Health MarketScan® Commercial Claims Databases throughout each given calendar year from 2003 to 2013, including 5,094,868 men in 2013. Trends in the yearly rates of testosterone replacement therapy use were calculated using Poisson regression. Among testosterone replacement therapy users, the Cochran-Armitage test was used to assess temporal trends in age, formulation type, semen analysis and serum testosterone level testing during the 12 months preceding the documented use of testosterone replacement therapy. Between 2003 and 2013, there was a fourfold increase in the rate of testosterone use among 18 to 45-year-old men from 29.2/10,000 person-years to 118.1/10,000 person-years (p replacement therapy users, topical gel formulations were initially most used. Injection use then doubled between 2009 and 2012 (23.5% and 46.2%, respectively) and surpassed topical gel use in 2013. In men 56 to 64 years old there was a statistically significant threefold increase in testosterone replacement therapy use (p replacement therapy use increased fourfold in men 18 to 45 years old compared to threefold in older men. This younger age group should be a focus for future studies due to effects on fertility and unknown long-term sequelae. Copyright © 2017 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Soil aggregation under different management systems

Directory of Open Access Journals (Sweden)

Cibele Mascioli Rebello Portella

2012-12-01

Full Text Available Considering that the soil aggregation reflects the interaction of chemical, physical and biological soil factors, the aim of this study was evaluate alterations in aggregation, in an Oxisol under no-tillage (NT and conventional tillage (CT, since over 20 years, using as reference a native forest soil in natural state. After analysis of the soil profile (cultural profile in areas under forest management, samples were collected from the layers 0-5, 5-10, 10-20 and 20-40 cm, with six repetitions. These samples were analyzed for the aggregate stability index (ASI, mean weighted diameter (MWD, mean geometric diameter (MGD in the classes > 8, 8-4, 4-2, 2-1, 1-0.5, 0.5-0.25, and < 0.25 mm, and for physical properties (soil texture, water dispersible clay (WDC, flocculation index (FI and bulk density (Bd and chemical properties (total organic carbon - COT, total nitrogen - N, exchangeable calcium - Ca2+, and pH. The results indicated that more intense soil preparation (M < NT < PC resulted in a decrease in soil stability, confirmed by all stability indicators analyzed: MWD, MGD, ASI, aggregate class distribution, WDC and FI, indicating the validity of these indicators in aggregation analyses of the studied soil.

Aggregate assesment and durability evaluation of optimized graded concrete in the state of Oklahoma

Science.gov (United States)

Ghaeezadeh, Ashkan

This research is a part of a larger project that emphasizes on creating a more scientific approach to designing concrete mixtures for concrete pavements that use less cement and more aggregate which is called optimized graded concrete. The most challenging obstacle in optimized mixtures is reaching enough workability so that one doesn't have to add more cement or super-plasticizer to reach the desired level of flowability. Aggregate gradation and characteristics have found to be very important when it comes to the workabaility of optimized graded concrete. In this research a new automated method of aggregate assessment was used to compare the shape and the surface of different aggregates as well as their influence on the concrete flowability. At the end, the performance of optimized graded concrete against drying shrinkage and freezing and thawing condition were investigated.

Building aggregate timber supply models from individual harvest choice

Science.gov (United States)

Maksym Polyakov; David N. Wear; Robert Huggett

2009-01-01

Timber supply has traditionally been modelled using aggregate data. In this paper, we build aggregate supply models for four roundwood products for the US state of North Carolina from a stand-level harvest choice model applied to detailed forest inventory. The simulated elasticities of pulpwood supply are much lower than reported by previous studies. Cross price...

OMERACT/OARSI initiative to define states of severity and indication for joint replacement in hip and knee osteoarthritis

DEFF Research Database (Denmark)

Gossec, Laure; Hawker, Gillian; Davis, Aileen M

2007-01-01

OBJECTIVE: Time to theoretical indication of joint replacement surgery has been proposed as a primary outcome for potential structure-modifying interventions for osteoarthritis (OA). The objectives of this OMERACT/OARSI Working Group were to identify pain, physical function, and structure states ...

COMMERCIAL DEMONSTRATION OF THE MANUFACTURED AGGREGATE PROCESSING TECHNOLOGY UTILIZING SPRAY DRYER ASH

Energy Technology Data Exchange (ETDEWEB)

Roy Scandrol

2003-10-01

Universal Aggregates, LLC proposes to design, construct and operate a lightweight aggregate manufacturing plant at the Birchwood Power Facility in King George, Virginia. The installation and start-up expenses for the Birchwood Aggregate Facility are $19.5 million. The DOE share is $7.2 million (37%) and the Universal Aggregates share is $12.3 (63%). The project team consists of CONSOL Energy Inc., P.J. Dick, Inc., SynAggs, LLC, and Universal Aggregates, LLC. The Birchwood Facility will transform 115,000 tons per year of spray dryer by-products that are currently being disposed of in an offsite landfill into 167,000 tons of a useful product, lightweight aggregates that can be used to manufacture lightweight aggregates that can be used to manufacture lightweight and medium weight masonry blocks. In addition to the environmental benefits, the Birchwood Facility will create nine (9) manufacturing jobs plus additional employment in the local trucking industry to deliver the aggregate to customers or reagents to the facility. A successful demonstration would lead to additional lightweight aggregate manufacturing facilities in the United States. There are currently twenty-one (21) spray dryer facilities operating in the United States that produce an adequate amount of spray dryer by-product to economically justify the installation of a lightweight aggregate manufacturing facility. Industry sources believe that as additional scrubbing is required, dry FGD technologies will be the technology of choice. Letters from potential lightweight aggregate customers indicate that there is a market for the product once the commercialization barriers are eliminated by this demonstration project.

COMMERCIAL DEMONSTRATION OF THE MANUFACTURED AGGREGATE PROCESSING TECHNOLOGY UTILIZING SPRAY DRYER ASH

Energy Technology Data Exchange (ETDEWEB)

Roy Scandrol

2003-04-01

Universal Aggregates, LLC proposes to design, construct and operate a lightweight aggregate manufacturing plant at the Birchwood Power Facility in King George, Virginia. The installation and start-up expenses for the Birchwood Aggregate Facility are $19.5 million. The DOE share is $7.2 million (37%) and the Universal Aggregates share is $12.3 (63%). The project team consists of CONSOL Energy Inc., P.J. Dick, Inc., SynAggs, LLC, and Universal Aggregates, LLC. The Birchwood Facility will transform 115,000 tons per year of spray dryer by-products that are currently being disposed of in an offsite landfill into 167,000 tons of a useful product, lightweight aggregates that can be used to manufacture lightweight aggregates that can be used to manufacture lightweight and medium weight masonry blocks. In addition to the environmental benefits, the Birchwood Facility will create eight (8) manufacturing jobs plus additional employment in the local trucking industry to deliver the aggregate to customers or reagents to the facility. A successful demonstration would lead to additional lightweight aggregate manufacturing facilities in the United States. There are currently twenty-one (21) spray dryer facilities operating in the United States that produce an adequate amount of spray dryer by-product to economically justify the installation of a lightweight aggregate manufacturing facility. Industry sources believe that as additional scrubbing is required, dry flue gas desulfurization (FGD) technologies will be the technology of choice. Letters from potential lightweight aggregate customers indicate that there is a market for the product once the commercialization barriers are eliminated by this demonstration project.

Aggregation-primed molten globule conformers of the p53 core domain provide potential tools for studying p53C aggregation in cancer.

Science.gov (United States)

Pedrote, Murilo M; de Oliveira, Guilherme A P; Felix, Adriani L; Mota, Michelle F; Marques, Mayra de A; Soares, Iaci N; Iqbal, Anwar; Norberto, Douglas R; Gomes, Andre M O; Gratton, Enrico; Cino, Elio A; Silva, Jerson L

2018-05-31

The functionality of the tumor suppressor p53 is altered in more than 50% of human cancers, and many individuals with cancer exhibit amyloid-like buildups of aggregated p53. An understanding of what triggers the pathogenic amyloid conversion of p53 is required for the further development of cancer therapies. Here, perturbation of the p53 core domain (p53C) with sub-denaturing concentrations of guanidine hydrochloride and high hydrostatic pressure revealed native-like molten globule (MG) states, a subset of which were highly prone to amyloidogenic aggregation. We found that MG conformers of p53C, likely representing population-weighted averages of multiple states, have different volumetric properties, as determined by pressure perturbation and size-exclusion chromatography. We also found that they bind the fluorescent dye 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid (bis-ANS) and have a native-like tertiary structure that occludes the single Trp residue in p53. Fluorescence experiments revealed conformational changes of the single Trp and Tyr residues before p53 unfolding and the presence of MG conformers, some of which were highly prone to aggregation. P53C exhibited marginal unfolding cooperativity, which could be modulated from unfolding to aggregation pathways with chemical or physical forces. We conclude that trapping amyloid precursor states in solution is a promising approach for understanding p53 aggregation in cancer. Our findings support the use of single-Trp fluorescence as a probe for evaluating p53 stability, effects of mutations, and the efficacy of therapeutics designed to stabilize p53. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

Recycled aggregates in concrete production: engineering properties and environmental impact

Directory of Open Access Journals (Sweden)

Seddik Meddah Mohammed

2017-01-01

Full Text Available Recycled concrete aggregate is considered as the most abundant and used secondary aggregate in concrete production, other types of solid waste are also being used in concrete for specific purposes and to achieve some desired properties. Recycled aggregates and particularly, recycled concrete aggregate substantially affect the properties and mix design of concrete both at fresh and hardened states since it is known by high porosity due to the adhered layer of old mortar on the aggregate which results in a high water absorption of the recycled secondary aggregate. This leads to lower density and strength, and other durability related properties. The use of most recycled aggregate in concrete structures is still limited to low strength and non-structural applications due to important drop in strength and durability performances generated. Embedding recycled aggregates in concrete is now a current practice in many countries to enhance sustainability of concrete industry and reduce its environmental impacts. The present paper discusses the various possible recycled aggregates used in concrete production, their effect on both fresh and hardened properties as well as durability performances. The economic and environmental impacts of partially or fully substituting natural aggregates by secondary recycled aggregates are also discussed.

Soil Overconsolidation Changes Caused by Dynamic Replacement

Science.gov (United States)

Piotr, Kanty; Sławomir, Kwiecień; Jerzy, Sękowski

2017-10-01

In the dynamic replacement method (DR) the soil is improved by initially dropping a large weight (typically 8-20 t) pounder from a significant height up to 25 m. The created crater is filled with a stronger material (gravel, rubble, stone aggregate, debris), and the pounder is dropped once or multiple times again. The construction of dynamic replacement pillars influences the parameters of the adjacent soil. It results from the energy generated by dropping a pounder into the soil. In the current practice, these changes are not taken into the account during the design. This paper focuses on the changes of overconsolidation ratio (OCR) and in situ coefficient of lateral earth pressure (K) values estimated base on cone penetration test (CPTU) and Dilatometric test (DMT) performed at a test site. A single column was constructed and the ground around the column was examined using CPTU and DMT, performed at different distances from the column centre (2, 3, 4 and 6 m) and at different time intervals (during construction and 1, 8, 30 days later). The column was constructed in so-called transition soils (between cohesive and non-cohesive). While interpreting the results of the research, the authors addressed the matter of choosing the procedure of OCR and K indication for transition soils (in this case described as silts and/or sandy silts). Overconsolidation changes may differ depending on the chosen analysis procedure (for cohesive or non-cohesive soils). On the basis of the analysis presented in the paper and the observation of soil (acknowledged as cohesive according to macroscopic observations) during column excavation, it was decided that for more detailed analyses methods dedicated to cohesive soils should be applied. Generally, it can be stated that although the changes were complex, DR pillar formation process resulted in the increase of these parameters. The average increases of OCR and K values were 25% and 10% respectively. The post installation values are not

Molecular origin of polyglutamine aggregation in neurodegenerative diseases.

Directory of Open Access Journals (Sweden)

2005-08-01

Full Text Available Expansion of polyglutamine (polyQ tracts in proteins results in protein aggregation and is associated with cell death in at least nine neurodegenerative diseases. Disease age of onset is correlated with the polyQ insert length above a critical value of 35-40 glutamines. The aggregation kinetics of isolated polyQ peptides in vitro also shows a similar critical-length dependence. While recent experimental work has provided considerable insights into polyQ aggregation, the molecular mechanism of aggregation is not well understood. Here, using computer simulations of isolated polyQ peptides, we show that a mechanism of aggregation is the conformational transition in a single polyQ peptide chain from random coil to a parallel beta-helix. This transition occurs selectively in peptides longer than 37 glutamines. In the beta-helices observed in simulations, all residues adopt beta-strand backbone dihedral angles, and the polypeptide chain coils around a central helical axis with 18.5 +/- 2 residues per turn. We also find that mutant polyQ peptides with proline-glycine inserts show formation of antiparallel beta-hairpins in their ground state, in agreement with experiments. The lower stability of mutant beta-helices explains their lower aggregation rates compared to wild type. Our results provide a molecular mechanism for polyQ-mediated aggregation.

Very early age concrete hydration characterization monitoring using piezoceramic based smart aggregates

International Nuclear Information System (INIS)

Kong, Qingzhao; Song, Gangbing; Hou, Shuang; Ji, Qing; Mo, Y L

2013-01-01

Very early age (0–20 h) concrete hydration is a complicated chemical reaction. During the very early age period, the concrete condition dramatically changes from liquid state to solid state. This paper presents the authors’ recent research on monitoring very early age concrete hydration characterization by using piezoceramic based smart aggregates. The smart aggregate (SA) transducer is designed as a sandwich structure using two marble blocks and a pre-soldered lead zirconate titanate (PZT) patch. Based on the electromechanical property of piezo materials, the PZT patches function as both actuators and sensors. In addition, the marble blocks provide reliable protection to the fragile PZT patch and develop the SA into a robust embedded actuator or sensor in the structure. The active-sensing approach, which involved a pair of smart aggregates with one as an actuator and the other one as a sensor, was applied in this paper’s experimental investigation of concrete hydration characterization monitoring. In order to completely understand the hydration condition of the inhomogeneous, over-cluttering, high-scattering characteristics of concrete (specifically of very early concrete), a swept sine wave and several constant frequency sine waves were chosen and produced by a function generator to excite the embedded actuating smart aggregate. The PZT vibration induced ultrasonic wave propagated through the concrete and was sent to the other smart aggregate sensor. The electrical signal transferred from the smart aggregate sensor was recorded during the test. As the concrete hydration reaction was occurring, the characteristic of the electrical signal continuously changed. This paper describes the successful investigation of the three states (the fluid state, the transition state, and the hardened state) of very early age concrete hydration based on classification of the received electrical signal. Specifically, the amplitude and frequency response of the electrical

Characterization of effects of thermal property of aggregate on the carbon footprint of asphalt industries in China

Directory of Open Access Journals (Sweden)

Ali Jamshidi

2017-04-01

Full Text Available In this study, the effects of the thermal properties of asphalt binders and aggregate materials were characterized in terms of the specific heat capacity (C for energy consumption and environmental footprints of hot mix asphalt (HMA and warm mix asphalt (WMA. Asphalt mixes produced using low-C aggregate are found to be more energy-efficient and environmental friendly, irrespective of the binder type and construction technology. Therefore, different fractions of aggregate blends were replaced with the aggregate provided from a low-C source or sustainable source. Analysis of energy consumption clearly indicated that the specific energy and environmental footprints decrease linearly as the low-C aggregate content increases. The amount of energy saving realized in the asphalt industries by the use of low-C aggregate is significant on a national scale in China. In this regard, China was chosen as a case study. Analysis of fuel requirement clearly indicated that the production of WMA using high thermal sensitivity aggregate can yield significant energy saving sufficient to fuel 44,007 to 664,880 Chinese households per year. Therefore, use of low C aggregate in asphalt mix production can be adopted as a strategy to produce WMA and HMA.

Enhancement of properties of recycled coarse aggregate concrete using bacteria

Science.gov (United States)

Sahoo; Arakha; Sarkar; P; Jha

2016-01-01

Due to rapid construction, necessity for raw materials of concrete, especially coarse aggregate, tends to increase the danger of early exhaustion of the natural resources. An alternative source of raw materials would perhaps delay the advent of this early exhaustion. Recycled coarse aggregate (RCA) plays a great role as an alternative raw material that can replace the natural coarse aggregate (NCA) for concrete. Previous studies show that the properties of RCA concrete are inferior in quality compared to NCA concrete. This article attempts to study the improvement of properties of RCA concrete with the addition of bacteria named as Bacillus subtilis. The experimental investigation was carried out to evaluate the improvement of the compressive strength, capillary water absorption, and drying shrinkage of RCA concrete incorporating bacteria. The compressive strength of RCA concrete is found to be increased by about 20% when the cell concentration of B. subtilis is 106 cells/ml. The capillary water absorption as well as drying shrinkage of RCA are reduced when bacteria is incorporated. The improvement of RCA concrete is confirmed to be due to the calcium carbonate precipitation as observed from the microstructure studies carried out on it such as EDX, SEM, and XRD.

Temperature dependence of erythrocyte aggregation in vitro by backscattering nephelometry

Science.gov (United States)

Sirko, Igor V.; Firsov, Nikolai N.; Ryaboshapka, Olga M.; Priezzhev, Alexander V.

1997-05-01

We apply backscattering nephelometry technique to register the alterations of the scattering signal from a whole blood sample due to appearance or disappearance of different types of erythrocyte aggregates in stasis and under controlled shear stress. The measured parameters are: the characteristic times of linear and 3D aggregates formation, and the strength of aggregates of different types. These parameters depend on the sample temperature in the range of 2 divided by 50 degrees C. Temporal parameters of the aggregation process strongly increase at temperature 45 degrees C. For samples of normal blood the aggregates strength parameters do not significantly depend on the sample temperature, whereas for blood samples from patients suffering Sjogren syndrome we observe high increase of the strength of 3D and linear aggregates and decrease of time of linear aggregates formation at low temperature of the sample. This combination of parameters is opposite to that observed in the samples of pathological blood at room temperature. Possible reasons of this behavior of aggregation state of blood and explanation of the observed effects will be discussed.

The dramatic increase in total knee replacement utilization rates in the United States cannot be fully explained by growth in population size and the obesity epidemic.

Science.gov (United States)

Losina, Elena; Thornhill, Thomas S; Rome, Benjamin N; Wright, John; Katz, Jeffrey N

2012-02-01

Total knee replacement utilization in the United States more than doubled from 1999 to 2008. Although the reasons for this increase have not been examined rigorously, some have attributed the increase to population growth and the obesity epidemic. Our goal was to investigate whether the rapid increase in total knee replacement use over the past decade can be sufficiently attributed to changes in these two factors. We used data from the Nationwide Inpatient Sample to estimate changes in total knee replacement utilization rates from 1999 to 2008, stratified by age (eighteen to forty-four years, forty-five to sixty-four years, and sixty-five years or older). We obtained data on obesity prevalence and U.S. population growth from federal sources. We compared the rate of change in total knee replacement utilization with the rates of population growth and change in obesity prevalence from 1999 to 2008. In 2008, 615,050 total knee replacements were performed in the United States adult population, 134% more than in 1999. During the same time period, the overall population size increased by 11%. While the population of forty-five to sixty-four-year-olds grew by 29%, the number of total knee replacements in this age group more than tripled. The number of obese and non-obese individuals in the United States increased by 23% and 4%, respectively. Assuming unchanged indications for total knee replacement among obese and non-obese individuals with knee osteoarthritis over the last decade, these changes fail to account for the 134% growth in total knee replacement use. Population growth and obesity cannot fully explain the rapid expansion of total knee replacements in the last decade, suggesting that other factors must also be involved. The disproportionate increase in total knee replacements among younger patients may be a result of a growing number of knee injuries and expanding indications for the procedure.

Utilisation of iron ore tailings as aggregates in concrete

OpenAIRE

Francis Atta Kuranchie; Sanjay Kumar Shukla; Daryoush Habibi; Alireza Mohyeddin

2015-01-01

Sustainable handling of iron ore tailings is of prime concern to all stakeholders who are into iron ore mining. This study seeks to add value to the tailings by utilising them as a replacement for aggregates in concrete. A concrete mix of grade 40 MPa was prepared in the laboratory with water–cement ratio of 0.5. The concrete were cured for 1, 2, 3, 7, 14 and 28 days. The properties of the concrete such as workability, durability, density, compressive strength and indirect tensile strength we...

Optimal strategies for a replacement model

NARCIS (Netherlands)

Bruns, P.B.

2000-01-01

We examine a replacement system with discrete-time Markovian deterioration and finite state space $\\{0,\\ldots,N\\}$. State 0 stands for a new system, and the higher the state the worse the system; a system in state $N$ is considered to be in a {\\it bad state}. We impose the condition that the

Acceleration of tropical cyclogenesis by self-aggregation feedbacks.

Science.gov (United States)

Muller, Caroline J; Romps, David M

2018-03-20

Idealized simulations of tropical moist convection have revealed that clouds can spontaneously clump together in a process called self-aggregation. This results in a state where a moist cloudy region with intense deep convection is surrounded by extremely dry subsiding air devoid of deep convection. Because of the idealized settings of the simulations where it was discovered, the relevance of self-aggregation to the real world is still debated. Here, we show that self-aggregation feedbacks play a leading-order role in the spontaneous genesis of tropical cyclones in cloud-resolving simulations. Those feedbacks accelerate the cyclogenesis process by a factor of 2, and the feedbacks contributing to the cyclone formation show qualitative and quantitative agreement with the self-aggregation process. Once the cyclone is formed, wind-induced surface heat exchange (WISHE) effects dominate, although we find that self-aggregation feedbacks have a small but nonnegligible contribution to the maintenance of the mature cyclone. Our results suggest that self-aggregation, and the framework developed for its study, can help shed more light into the physical processes leading to cyclogenesis and cyclone intensification. In particular, our results point out the importance of the longwave radiative cooling outside the cyclone.

45 CFR 201.70 - Treatment of replacement checks.

Science.gov (United States)

2010-10-01

... 45 Public Welfare 2 2010-10-01 2010-10-01 false Treatment of replacement checks. 201.70 Section... STATES FOR PUBLIC ASSISTANCE PROGRAMS Review and Audits § 201.70 Treatment of replacement checks. (a... (FFP) for replacement checks under titles I, VI-A, X, XIV, XVI (AABD) except under the circumstances...

Consequential secondary structure alterations and aggregation during prolonged casein glycation.

Science.gov (United States)

Jindal, Supriya; Naeem, Aabgeena

2013-05-01

Non-enzymatic glycosylation (glycation) of casein is a process used not just to ameliorate the quality of dairy products but also to increase the shelf life of canned foods, including baby milk supplements. Incubation of κ-casein with reducing sugars for 15 days at physiological temperature showed the formation of a molten globule state at day 9 and 12 during fructation and glucation respectively. This state exhibits substantial secondary structure and maximum ANS binding. Later on, glycation resulted in the formation of aggregates at day 12 in presence of fructose and day 15 in presence of glucose. Aggregates possess extensive β-sheet structure as revealed by far-UV CD and FTIR. These aggregates showed altered tryptophan environment, decrease ANS binding relative to molten globule state and increase in Thioflavin T fluorescence. Aggregates were also accompanied by the accumulation of AGEs, indicative of structural damage to the protein and formation of potentially harmful species at the physiological level. Fructose was more reactive than glucose and thus caused early and significant changes in the protein. From our studies, we conclude that controlling the extent of the Maillard reaction in the food industry is essential to counter its negative effects and expand its safety spectrum.

Ionic liquid-induced aggregate formation and their applications.

Science.gov (United States)

Dutta, Rupam; Kundu, Sangita; Sarkar, Nilmoni

2018-06-01

In the last two decades, researchers have extensively studied highly stable and ordered supramolecular assembly formation using oppositely charged surfactants. Thereafter, surface-active ionic liquids (SAILs), a special class of room temperature ionic liquids (RTILs), replace the surfactants to form various supramolecular aggregates. Therefore, in the last decade, the building blocks of the supramolecular aggregates (micelle, mixed micelle, and vesicular assemblies) have changed from oppositely charged surfactant/surfactant pair to surfactant/SAIL and SAIL/SAIL pair. It is also found that various biomolecules can also interact with SAILs to construct biologically important supramolecular assemblies. The very latest addition to this combination of ion pairs is the dye molecules having a long hydrophobic chain part along with a hydrophilic ionic head group. Thus, dye/surfactant or dye/SAIL pair also produces different assemblies through electrostatic, hydrophobic, and π-π stacking interactions. Vesicles are one of the important self-assemblies which mimic cellular membranes, and thus have biological application as a drug carrier. Moreover, vesicles can act as a suitable microreactor for nanoparticle synthesis.

Durability of recycled aggregate concrete using pozzolanic materials.

Science.gov (United States)

Ann, K Y; Moon, H Y; Kim, Y B; Ryou, J

2008-01-01

In this study, pulverized fuel ash (PFA) and ground granulated blast furnace slag (GGBS) were used to compensate for the loss of strength and durability of concrete containing recycled aggregate. As a result, 30% PFA and 65% GGBS concretes increased the compressive strength to the level of control specimens cast with natural granite gravel, but the tensile strength was still lowered at 28 days. Replacement with PFA and GGBS was effective in raising the resistance to chloride ion penetrability into the concrete body, measured by a rapid chloride ion penetration test based on ASTM C 1202-91. It was found that the corrosion rate of 30% PFA and 65% GGBS concretes was kept at a lower level after corrosion initiation, compared to the control specimens, presumably due to the restriction of oxygen and water access. However, it was less effective in increasing the chloride threshold level for steel corrosion. Hence, it is expected that the corrosion time for 30% PFA and 65% GGBS concrete containing recycled aggregate mostly equates to the corrosion-free life of control specimens.

Development of lightweight concrete mixes for construction industry at the state of Arkansas

Science.gov (United States)

Almansouri, Mohammed Abdulwahab

As the construction industry evolved, the need for more durable, long lasting infrastructure increased. Therefore, more efforts have been put to find new methods to improve the properties of the concrete to prolong the service life of the structural elements. One of these methods is the use of lightweight aggregate as an internal curing agent to help reducing self-desiccation and shrinkage. This research studied the effects of using locally available lightweight aggregate (expanded clay), as a partial replacement of normal weight aggregate in the concrete matrix. The concrete mixtures contained lightweight aggregate with a replacement percentage of 12.5, 25, 37.5, and 50 percent by volume. Fresh properties as well as compressive strength, modulus of rupture, and drying shrinkage were measured. While was effective in reducing drying shrinkage, the use of lightweight aggregate resulted in slightly reducing both the compressive strength and modulus of rupture.

On aggregation of relaxed T-indistinguishability operators

Energy Technology Data Exchange (ETDEWEB)

Fuster-Parra, P.

2017-07-01

The notion of T -indistinguishability operator was introduced by E. Trillas in [7] with the aim of fuzzifying the classical (crisp) notion of equivalence relation. Relaxed metrics and indistinguishability operators are closely related. Indeed, in [1] it has been stated that the logical counterpart for relaxed metrics is, in some sense, a generalized indistinguishability operator (relaxed T -indistinguishability operator). Notice that the notion of T -indistinguishability operator is retrieved as a particular case of relaxed T -indistinguishability operator whenever the relaxed T - indistinguishability operator satisfies also the reflexivity. In fact, a relaxed indistinguishability operator is a indistinguishability operator if and only if it holds the reflexivity. The same occurs when we consider T -indistinguishability operator that separates points. Several authors have studied the aggregation of some classes of fuzzy relations (see [3, 4, 5, 6]), where it is stated that transitivity is one of the most important properties of a fuzzy relation. In [5] a study of aggregation of T-indistinguishability operators is presented, motivated by this work the aim of this study is to analyze the case of aggregating relaxed T-indistinguishability operators. (Author)

Principles of Need and the Aggregation Thesis.

Science.gov (United States)

Gustavsson, Erik; Juth, Niklas

2017-09-02

Principles of need are constantly referred to in health care priority setting. The common denominator for any principle of need is that it will ascribe some kind of special normative weight to people being worse off. However, this common ground does not answer the question how a plausible principle of need should relate to the aggregation of benefits across individuals. Principles of need are sometimes stated as being incompatible with aggregation and sometimes characterized as accepting aggregation in much the same way as utilitarians do. In this paper we argue that if one wants to take principles of need seriously both of these positions have unreasonable implications. We then characterize and defend a principle of need consisting of sufficientarian elements as well as prioritarian which avoids these unreasonable implications.

Study on Quality Aggregate Construction Powder

International Nuclear Information System (INIS)

Myat Ko; Kyaw Naing; Thazin Lwin; Khin Mar Tun

2008-03-01

This research work deals with a view to promote cement replacement materials i-e aggregate construction powder, also known as building powder or construction powder . It has been used as lime substituent in construction work in Myanmar since 1990's. It is mixed with other construction materials such as cement, sand, etc. and used in plastering, tiling, arranging bricks and smoothing the face of the buildings.This work also deals with some aspects in physical properties of four different aggregate construction powder samples such as Moe Hein, Man Thiri, Shwe Taung and Kyauk Sue. In addition, these four different samples were characterized by using spectroscopic methods such as ED-XRF, AAS, FT-IR and XRD. In support of the finding by the analytical assays of Moe Hein aggregate construction powder, it indicated the percent composition of the presence of SiO2 12.13%, Al2O3 7.40%, Fe2O3 0.94%, CaO 41.00%,MgO 1.50% total sulphur 1.15%, chloride 1.49%, carbonate 43.63% and sulphate 3.44%. The analytical assays of Sin Min cement, Kyant cement, brick powder and pozzolan were also carried out in this research work. The mixing between various ratios of Moe Hein and Kyant cement as well as Sin Min II cement were done and their mechanical strengths such as setting time, tensile strength and compressive strength of each sample were studied. The quality of mixing ratio 50:50 of Moe Hein and Kyant cement was found to be comparable to the ASTM standard type II Protland cement which is for general use.

Use of fuzzy set theory in the aggregation of expert judgments

International Nuclear Information System (INIS)

Moon, Joo Hyun; Kang, Chang Sun

1999-01-01

It is sometimes impossible to make a correct decision in a certain engineering task without the help from professional expert judgments. Even though there are different expert opinions available, however, they should be appropriately aggregated to a useful form for making an acceptable engineering decision. This paper proposes a technique which utilizes the fuzzy set theory in the aggregation of expert judgments. In the technique, two main key concepts are employed: linguistic variables and fuzzy numbers. Linguistic variables first represent the relative importance of evaluation criteria under consideration and the degree of confidence on each expert perceived by the decision maker, and then are replaced by suitable triangular fuzzy numbers for arithmetic manipulation. As a benchmark problem, the pressure increment in the containment of Sequoyah nuclear power plant due to reactor vessel breach was estimated to verify and validate the proposed technique

Specification aggregate quarry expansion: a case study demonstrating sustainable management of natural aggregate resources

Science.gov (United States)

Langer, William H.; Tucker, M.L.

2003-01-01

Many countries, provinces, territories, or states in the European Union, Australia, Canada, the United States, and elsewhere have begun implementing sustainability programs, but most of those programs stop short of sustainable management of aggregate resources. Sustainable practices do not always have to be conducted under the title of sustainability. This case study describes how Lafarge, a large multinational construction materials supplier, implemented the principles of sustainability even though there was an absence of existing local government policies or procedures addressing sustainable resource management. Jefferson County, Colorado, USA, is one of three counties in the six-county Denver, Colorado, region that has potentially available sources of crushed stone. Crushed stone comprises 30 percent of the aggregate produced in the area and plays a major role in regional aggregate resource needs. Jefferson County is home to four of the five crushed stone operations in the Denver region. Lafarge operates one of those four quarries. Lafarge recently proposed to expand its reserves by exchanging company-owned land for existing dedicated open space land adjacent to their quarry but owned by Jefferson County. A similar proposal submitted about 10 years earlier had been denied. Contrary to the earlier proposal, which was predicated on public relations, the new proposal was predicated on public trust. Although not explicitly managed under the moniker of sustainability, Lafarge used basic management principles that embody the tenets of sustainability. To achieve the goals of sustainable aggregate management where no governmental policies existed, Lafarge not only assumed their role of being a responsible corporate and environmental member of the community, but also assumed the role of facilitator to encourage and enable other stakeholders to responsibly resolve legitimate concerns regarding the Lafarge quarry proposal. Lafarge successfully presented an enlightened

Equipment Replacement Decision Making: Opportunities and Challenges

OpenAIRE

Fan, Wei (David); Gemar, Mason D.; Machemehl, Randy

2012-01-01

The primary function of equipment managers is to replace the right equipment at the right time and at the lowest overall cost. In this paper, the opportunities and challenges associated with equipment replacement optimization (ERO) are discussed in detail. First, a comprehensive review of the state-of-the art and state-of-the practice literature for the ERO problem is conducted. Second, a dynamic programming (DP) based optimization solution methodology is presented to solve the ERO problem. T...

FRP-Confined Recycled Coarse Aggregate Concrete: Experimental Investigation and Model Comparison

Directory of Open Access Journals (Sweden)

Yingwu Zhou

2016-10-01

Full Text Available The in situ application of recycled aggregate concrete (RAC is of great significance in environmental protection and construction resources sustainability. However, it has been limited to nonstructural purposes due to its poor mechanical performance. External confinement using steel tubes and fiber-reinforced polymer (FRP can significantly improve the mechanical performance of RAC and thus the first-ever study on the axial compressive behavior of glass FRP (GFRP-confined RAC was recently reported. To have a full understanding of FRP-confined RAC, this paper has extended the type of FRP and presents a systematic experimental study on the axial compressive performance of carbon FRP (CFRP-confined RAC. The mechanical properties of CFRP-confined RAC from the perspective of the failure mode, ultimate strength and strain, and stress–strain relationship responses were analyzed. Integrated with existing experimental data of FRP-confined RAC, the paper compiles a database for the mechanical properties of FRP-confined RAC. Based on the database, the effects of FRP type (i.e., GFRP and CFRP and the replacement ratio of recycled coarse aggregate were investigated. The results indicated that the stress–stain behavior of FRP-confined RAC depended heavily on the unconfined concrete strength and the FRP confining pressure instead of the replacement ratio. Therefore, this study adopted eleven high-performance ultimate strength and strain models developed for FRP-confined normal aggregate concrete (NAC to predict the mechanical properties of FRP-confined RAC. All the predictions had good agreement with the test results, which further confirmed similar roles played by FRP confinement in improving the mechanical properties of RAC and improving those of NAC. On this basis, this paper finally recommended a stress–strain relationship model for FRP-confined RAC.

REPLACEMENT CONTROL OF INNOVATION MANAGERS: ORGANIZATIONAL AND ECONOMIC ASPECTS

Directory of Open Access Journals (Sweden)

E. V. Gurina

2011-01-01

Full Text Available The paper substantiates phases of specialists’ replacement ensuring innovation development of the national economy in Belarus, i.e. managers of innovation activity. Realization of replacement phases is presented within the system consisting of four blocks – objective, managing, controllable and providing. Analysis results of the current state of the innovation activity managers replacement system reveal main problems in interaction of its basic agents. The paper considers solution of specified problems in the context of formation of organizational and economic approaches to managing the innovation activity managers replacement system which presupposes modernization of organizational interrelations between state- run public authorities in the managing block and micro-incentive structures in the controllable block as well as the usage of the process approach in every phase of the replacement process. 

Geology-based planning and the aggregate industry - Perspectives from opposite sides of the globe

Science.gov (United States)

Stephens, A.W.; Langer, W.H.

2006-01-01

In Australia and in the United States, encroachment by conflicting land uses, zoning restrictions and the "not-in-my-backyard" syndrome make it increasingly difficult to access high-quality aggregate resources located near their market areas. Attempts by government agencies in the United States to protect aggregate resources for future development have met with varying degrees of success. The State of Queensland, Australia, designates aggregate resource areas as Key Resource Areas. These protect the resource and the routes to transport the resource, provide a separation area from incompatible land uses and indicate the likelihood that the area is free from conflicting social or environmental issues.

Aggregated wind power generation probabilistic forecasting based on particle filter

International Nuclear Information System (INIS)

Li, Pai; Guan, Xiaohong; Wu, Jiang

2015-01-01

Highlights: • A new method for probabilistic forecasting of aggregated wind power generation. • A dynamic system is established based on a numerical weather prediction model. • The new method handles the non-Gaussian and time-varying wind power uncertainties. • Particle filter is applied to forecast predictive densities of wind generation. - Abstract: Probability distribution of aggregated wind power generation in a region is one of important issues for power system daily operation. This paper presents a novel method to forecast the predictive densities of the aggregated wind power generation from several geographically distributed wind farms, considering the non-Gaussian and non-stationary characteristics in wind power uncertainties. Based on a mesoscale numerical weather prediction model, a dynamic system is established to formulate the relationship between the atmospheric and near-surface wind fields of geographically distributed wind farms. A recursively backtracking framework based on the particle filter is applied to estimate the atmospheric state with the near-surface wind power generation measurements, and to forecast the possible samples of the aggregated wind power generation. The predictive densities of the aggregated wind power generation are then estimated based on these predicted samples by a kernel density estimator. In case studies, the new method presented is tested on a 9 wind farms system in Midwestern United States. The testing results that the new method can provide competitive interval forecasts for the aggregated wind power generation with conventional statistical based models, which validates the effectiveness of the new method

EAF Slag Aggregate in Roller-Compacted Concrete Pavement: Effects of Delay in Compaction

Directory of Open Access Journals (Sweden)

My Ngoc-Tra Lam

2018-04-01

Full Text Available This study investigates the effect of delay in compaction on the optimum moisture content and the mechanical propertie s (i.e., compressive strength, ultrasonic pulse velocity, splitting tensile strength, and modulus of elasticity of roller-compacted concrete pavement (RCCP made of electric arc furnace (EAF slag aggregate. EAF slag with size in the range of 4.75–19 mm was used to replace natural coarse aggregate in RCCP mixtures. A new mixing method was proposed for RCCP using EAF slag aggregate. The optimum moisture content of RCCP mixtures in this study was determined by a soil compaction method. The Proctor test assessed the optimum moisture content of mixtures at various time after mixing completion (i.e., 0, 15, 30, 60, and 90 min. Then, the effect of delay in compaction on the mechanical properties of RCCP mixtures at 28 days of age containing EAF slag aggregate was studied. The results presented that the negative effect on water content in the mixture caused by the higher water absorption characteristic of EAF slag was mitigated by the new mixing method. The optimum water content and maximum dry density of RCCP experience almost no effect from the delay in compaction. The compressive strength and splitting tensile strength of RCCP using EAF slag aggregate fulfilled the strength requirements for pavement with 90 min of delay in compaction.

Communal spaces: aggregation and integration in the Mogollon Region of the United States Southwest

Energy Technology Data Exchange (ETDEWEB)

Nisengard, Jennifer E.

2006-12-01

Aggregation and integration are processes that occur in human societies throughout the globe. An informative example of population aggregation and social integration can be observed in the North American desert borderlands from A.D. 250 to 1450 in the area known as the Mogollon region. In fact, Mogollon communities oscillated from smaller social groups into larger ones and dispersed into smaller groups only to form larger ones again. For this reason, examining the groups of people living in the Mogollon region provides a magnified view of social change over a substantial period. Understanding patterns of aggregation and integration provides researchers with the promise for research into the nature of these phenomena. In general, the Mogollon region is characterized by limited water supplies and low average annual precipitation. However, pockets of the Mogollon area, including the Mimbres valley and the Gila River valley, represent oases, where permanent rivers and their associated tributaries allowed for the pursuit of agricultural endeavors and access to a wide variety of wild plant and animal resources. The areas with these kinds of potential became population centers for previously dispersed groups of people living in the region. These people exploited natural resources and practiced agriculture in areas surrounding their communities. Over time, more organized aggregated and socially integrated communities were established throughout the region. Using ancient Mogollon communal architecture, commonly called kivas, this study examines issues of, and evidence for, population aggregation and social integration.

ATPase Domain and Interdomain Linker Play a Key Role in Aggregation of Mitochondrial Hsp70 Chaperone Ssc1*

Science.gov (United States)

Blamowska, Marta; Sichting, Martin; Mapa, Koyeli; Mokranjac, Dejana; Neupert, Walter; Hell, Kai

2010-01-01

The co-chaperone Hep1 is required to prevent the aggregation of mitochondrial Hsp70 proteins. We have analyzed the interaction of Hep1 with mitochondrial Hsp70 (Ssc1) and the determinants in Ssc1 that make it prone to aggregation. The ATPase and peptide binding domain (PBD) of Hsp70 proteins are connected by a linker segment that mediates interdomain communication between the domains. We show here that the minimal Hep1 binding entity of Ssc1 consists of the ATPase domain and the interdomain linker. In the absence of Hep1, the ATPase domain with the interdomain linker had the tendency to aggregate, in contrast to the ATPase domain with the mutated linker segment or without linker, and in contrast to the PBD. The closest homolog of Ssc1, bacterial DnaK, and a Ssc1 chimera, in which a segment of the ATPase domain of Ssc1 was replaced by the corresponding segment from DnaK, did not aggregate in Δhep1 mitochondria. The propensity to aggregate appears to be a specific property of the mitochondrial Hsp70 proteins. The ATPase domain in combination with the interdomain linker is crucial for aggregation of Ssc1. In conclusion, our results suggest that interdomain communication makes Ssc1 prone to aggregation. Hep1 counteracts aggregation by binding to this aggregation-prone conformer. PMID:20007714

ATPase domain and interdomain linker play a key role in aggregation of mitochondrial Hsp70 chaperone Ssc1.

Science.gov (United States)

Blamowska, Marta; Sichting, Martin; Mapa, Koyeli; Mokranjac, Dejana; Neupert, Walter; Hell, Kai

2010-02-12

The co-chaperone Hep1 is required to prevent the aggregation of mitochondrial Hsp70 proteins. We have analyzed the interaction of Hep1 with mitochondrial Hsp70 (Ssc1) and the determinants in Ssc1 that make it prone to aggregation. The ATPase and peptide binding domain (PBD) of Hsp70 proteins are connected by a linker segment that mediates interdomain communication between the domains. We show here that the minimal Hep1 binding entity of Ssc1 consists of the ATPase domain and the interdomain linker. In the absence of Hep1, the ATPase domain with the interdomain linker had the tendency to aggregate, in contrast to the ATPase domain with the mutated linker segment or without linker, and in contrast to the PBD. The closest homolog of Ssc1, bacterial DnaK, and a Ssc1 chimera, in which a segment of the ATPase domain of Ssc1 was replaced by the corresponding segment from DnaK, did not aggregate in Delta hep1 mitochondria. The propensity to aggregate appears to be a specific property of the mitochondrial Hsp70 proteins. The ATPase domain in combination with the interdomain linker is crucial for aggregation of Ssc1. In conclusion, our results suggest that interdomain communication makes Ssc1 prone to aggregation. Hep1 counteracts aggregation by binding to this aggregation-prone conformer.

Potential nutritional and economic effects of replacing juice with fruit in the diets of children in the United States.

Science.gov (United States)

Monsivais, Pablo; Rehm, Colin D

2012-05-01

To estimate the nutritional and economic effects of substituting whole fruit for juice in the diets of children in the United States. Secondary analyses using the 2001-2004 National Health and Nutrition Examination Survey and a national food prices database. Energy intakes, nutrient intakes, and diet costs were estimated before and after fruit juices were completely replaced with fruit in 3 models that emphasized fruits that were fresh, inexpensive, and widely consumed and in a fourth model that partially replaced juice with fruit, capping juice at recommended levels. A nationwide, representative sample of children in the United States. A total of 7023 children aged 3 to 18 years. Systematic complete or partial replacement of juice with fruit. Difference in energy intakes, nutrient intakes, and diet costs between observed and modeled diets. For children who consumed juice, replacement of all juice servings with fresh, whole fruit led to a projected reduction in dietary energy of 233 kJ/d (-2.6% difference [95% CI, -5.1% to -0.1%]), an increase in fiber of 4.3 g/d (31.1% difference [95% CI, 26.4%-35.9%]), and an increase in diet cost of $0.54/d (13.3% difference [95% CI, 8.8%-17.8%]). Substitution of juice with fresh fruit has the potential to reduce energy intake and improve the adequacy of fiber intake in children's diets. This would likely increase costs for schools, childcare providers, and families. These cost effects could be minimized by selecting processed fruits, but fewer nutritional gains would be achieved.

Optimal policies for aggregate recycling from decommissioned forest roads.

Science.gov (United States)

Thompson, Matthew; Sessions, John

2008-08-01

To mitigate the adverse environmental impact of forest roads, especially degradation of endangered salmonid habitat, many public and private land managers in the western United States are actively decommissioning roads where practical and affordable. Road decommissioning is associated with reduced long-term environmental impact. When decommissioning a road, it may be possible to recover some aggregate (crushed rock) from the road surface. Aggregate is used on many low volume forest roads to reduce wheel stresses transferred to the subgrade, reduce erosion, reduce maintenance costs, and improve driver comfort. Previous studies have demonstrated the potential for aggregate to be recovered and used elsewhere on the road network, at a reduced cost compared to purchasing aggregate from a quarry. This article investigates the potential for aggregate recycling to provide an economic incentive to decommission additional roads by reducing transport distance and aggregate procurement costs for other actively used roads. Decommissioning additional roads may, in turn, result in improved aquatic habitat. We present real-world examples of aggregate recycling and discuss the advantages of doing so. Further, we present mixed integer formulations to determine optimal levels of aggregate recycling under economic and environmental objectives. Tested on an example road network, incorporation of aggregate recycling demonstrates substantial cost-savings relative to a baseline scenario without recycling, increasing the likelihood of road decommissioning and reduced habitat degradation. We find that aggregate recycling can result in up to 24% in cost savings (economic objective) and up to 890% in additional length of roads decommissioned (environmental objective).

International examples of steam generator replacement

International Nuclear Information System (INIS)

Wiechmann, K.

1993-01-01

Since 1979-1980 a total of twelve nuclear power plants world-wide have had their steam generators replaced. The replacement of the Combustion steam generators in the Millstone-2 plant in the United States was completed very recently. Steam generator replacement activities are going on at present in four plants. In North Anna, the steam generators have been under replacement since January 1990. In Japan, preparations have been started for Genkai-1. Since January 1992, the two projects in Beznau-1, Switzerland, and Doel-3, Belgium, have bee planned and executed in parallel. Why steam generator replacement? There are a number of defect mechanisms which give rise to the need for early steam generator replacement. One of the main reasons is the use of Inconel-600 as material for the heating tubes. Steam generator heating tubes made of Inconel-600 have been known to exhibit their first defects due to stress corrosion cracking after less than one year of operation. (orig.) [de

Modulating and modeling aggregation of cell-seeded microcarriers in stirred culture system for macrotissue engineering.

Science.gov (United States)

Mei, Yang; Luo, Houyong; Tang, Qiang; Ye, Zhaoyang; Zhou, Yan; Tan, Wen-Song

2010-11-01

A recently developed protocol, "microtissue assembly" holds great promise to address the issue of limited mass transfer within engineered large tissue replacements (macrotissues), wherein small "building blocks" (microtissues) are prepared and then assembled into macrotissues. Previous studies suggested that aggregation behavior of microcarrier-based microtissues were very important for macrotissue engineering. However, a systematic study on the aggregation behavior of microtissues is still missing. In this study, to examine the aggregation behavior of microtissues, effects of key operation parameters in dynamic culture including cell seeding density, microcarrier concentration, L-ascorbic acid 2-phosphate (V(c)) and agitating speed were investigated. The aggregation process could be divided into three phases (i.e., lag, growth and stable). Aggregation efficiency (S) was found to be modulated by cell seeding density, microcarrier concentration, addition of V(c) and agitating speed. A mathematical model correlating the operation parameters with S at different phases of aggregation was developed and experimentally proved to be able to predict S with varied operation parameters. In the end, a cylindrical macrotissue (diameter × height: 2.0 cm × 0.8 cm) with fairly good integrity and cellularity and uniform cell distribution was successfully engineered through perfusion assembling microtissues with controlled S under selected culture conditions. Our study showed that aggregation of microtissues could be precisely modulated, which would definitely facilitate engineering macrotissues with high quality. Copyright © 2010 Elsevier B.V. All rights reserved.

Online Coupling of Flow-Field Flow Fractionation and Single Particle Inductively Coupled Plasma-Mass Spectrometry: Characterization of Nanoparticle Surface Coating Thickness and Aggregation State

Science.gov (United States)

Surface coating thickness and aggregation state have strong influence on the environmental fate, transport, and toxicity of engineered nanomaterials. In this study, flow-field flow fractionation coupled on-line with single particle inductively coupled plasma-mass spectrometry i...

Technical viability of self-compacting concretes with by-products from crushed coarse aggregate production

Directory of Open Access Journals (Sweden)

Edgar Bacarji

Full Text Available Abstract The main objective of this work is to present the technical viability of Self Compacting Concretes (SCC containing by-products from crushed coarse aggregate production. For this purpose, a vast characterization of these by-products was made; six mixtures of SCC were produced using two different aggregates: granite and mica schist. The binder/dry aggregate (b/agg ratio by mass was 1:3. The following properties were analyzed: compressive strength, direct tensile strength, flexural tensile strength and splitting tensile strength. Granite presented the best mechanical performance. The replacement of natural sand by granite sand generated concretes with the same level of compressive strength and caused an increase in tensile strength values. The incorporation of silica fume into concrete with granite produced an increase of 17% in compressive strength. So, the use of these by-product materials can provide a technically feasible solution that is also consistent with the aims of sustainable development and preservation of the environment.

Self-consolidating concretes containing waste PET bottles as sand replacement

Science.gov (United States)

Khalid, Faisal Sheikh; Azmi, Nurul Bazilah; Mazenan, Puteri Natasya; Shahidan, Shahiron; Othman, Nor hazurina; Guntor, Nickholas Anting Anak

2018-02-01

This study evaluates the effect of self-consolidating concrete (SCC) containing waste polyethylene terephthalate (PET) granules on the fresh, mechanical and water absorption properties. Fine aggregates were replaced from 0% to 8% by PET granules. The fresh properties of SCC containing PET granules were determined using slump flow and V-funnel flow time tests. The compressive and splitting tensile strength were evaluated. The results indicated that utilization of waste PET granules in production of SCC could be an effective way for recycling purpose. The maximum amount of PET replacement should be limited to 5%. Exceeding 5% of PET content may result in an increase of V-funnel flow time to overpass the limiting value, decrease in strength. The production of high performance SCC containing 5% PET granules satisfies all the requirements for SCC with satisfactory outputs.

Reactor console replacement at Washington State University

International Nuclear Information System (INIS)

Lovas, Thomas A.

1978-01-01

A replacement reactor console was installed in 1977 at the W.S.U. 1 MW TRIGA-fueled reactor as the final step in an instrumentation upgrade program. The program was begun circa 1972 with the design, construction and installation of various systems and equipment. Major instruments were installed in the existing console and tested in the course of reactor operation. The culmination of the program was the installation of a cubicle designed and constructed to house the updated instrumentation. (author)

Performance Evaluation of Stone Mastic Asphalt and Hot Mix Asphalt Mixtures Containing Recycled Concrete Aggregate

Directory of Open Access Journals (Sweden)

Mohammad Saeed Pourtahmasb

2014-01-01

Full Text Available Environmental and economic considerations have encouraged civil engineers to find ways to reuse recycled materials in new constructions. The current paper presents an experimental research on the possibility of utilizing recycled concrete aggregates (RCA in stone mastic asphalt (SMA and hot mix asphalt (HMA mixtures. Three categories of RCA in various percentages were mixed with virgin granite aggregates to produce SMA and HMA specimens. The obtained results indicated that, regardless of the RCA particular sizes, the use of RCA to replace virgin aggregates increased the needed binder content in the asphalt mixtures. Moreover, it was found that even though the volumetric and mechanical properties of the asphalt mixtures are highly affected by the sizes and percentages of the RCA but, based on the demands of the project and traffic volume, utilizing specific amounts of RCA in both types of mixtures could easily satisfy the standard requirements.

Study of the behavior of aggregate of calcined clay for use in permeable pavements for the city of Manaus; Estudo do comportamento de agregado sintetico de argila calcinada para uso em pavimentos permeaveis para a cidade de Manaus

Energy Technology Data Exchange (ETDEWEB)

Oliveira, M.S.; Vilela, P.A.T.; Araujo, V.S., E-mail: oliveirasmichelle@gmail.com [Universidade do Estado do Amazonas (UEAM), AM (Brazil)

2016-07-01

Research on the production of ceramic aggregates and their use in paving in the country began in the 80’s in the search for an alternative material that could replace the pebble or crushed stone, studied the clay, considered an abundant mineral resource by virtue of being the predominant soil in this region and which were made synthetic calcinated clay aggregates (ASAC), for their application in permeable paving concrete motivated by the lack of permeable areas. The study consists of the characterization of materials for manufacture of concrete slabs permeable and the assessment of the effects of synthetic aggregate on its properties in fresh and hardened state. The ceramic bodies were subjected to tests of X-ray diffraction, determination of chemical composition and plasticity. The results indicate that the use of synthetic clusters is a viable alternative for the production of porous concrete. (author)

Aggregation process, application to nuclear multifragmentation

International Nuclear Information System (INIS)

Garcia, Jean-Baptiste

1995-01-01

It is depicted an aggregation model (applied to nuclear multifragmentation) which I have elaborated and validated. This model contains an aggregation procedure, allowing one to determine the aggregation state of a given system. It takes into account spatial and kinetic nucleonic information, as well as in-medium effects. It is made of several energetic linkage criterions, all based on a single quantity: the energy of a system computed in its center of mass frame. This procedure has been applied to nuclear physics, assuming nucleus as a mix of two Fermi gas, interacting via the Yukawa potential (plus Coulomb in between protons) and obeying to a classical exclusion principle. The general trends of the model match with those of nuclear physics. Moreover, two comparisons between the model and nuclear multifragmentation experiments (ALADIN, then FOPI) exhibit nice agreements. The FOPI one, shows that fragments are bound to be formed at the beginning of the expansion phase (Au + Au at 150 MeV/nuc, for central collisions). This work ends with a study of the main ingredients included in the model. It reveals that in-medium effects, exclusion principle as well as the shape of the potential have a non negligible influence on the studied nuclear aggregation process. (author) [fr

Marine Synechococcus Aggregation

Science.gov (United States)

Neuer, S.; Deng, W.; Cruz, B. N.; Monks, L.

2016-02-01

Cyanobacteria are considered to play an important role in the oceanic biological carbon pump, especially in oligotrophic regions. But as single cells are too small to sink, their carbon export has to be mediated by aggregate formation and possible consumption by zooplankton producing sinking fecal pellets. Here we report results on the aggregation of the ubiquitous marine pico-cyanobacterium Synechococcus as a model organism. We first investigated the mechanism behind such aggregation by studying the potential role of transparent exopolymeric particles (TEP) and the effects of nutrient (nitrogen or phosphorus) limitation on the TEP production and aggregate formation of these pico-cyanobacteria. We further studied the aggregation and subsequent settling in roller tanks and investigated the effects of the clays kaolinite and bentonite in a series of concentrations. Our results show that despite of the lowered growth rates, Synechococcus in nutrient limited cultures had larger cell-normalized TEP production, formed a greater volume of aggregates, and resulted in higher settling velocities compared to results from replete cultures. In addition, we found that despite their small size and lack of natural ballasting minerals, Synechococcus cells could still form aggregates and sink at measureable velocities in seawater. Clay minerals increased the number and reduced the size of aggregates, and their ballasting effects increased the sinking velocity and carbon export potential of aggregates. In comparison with the Synechococcus, we will also present results of the aggregation of the pico-cyanobacterium Prochlorococcus in roller tanks. These results contribute to our understanding in the physiology of marine Synechococcus as well as their role in the ecology and biogeochemistry in oligotrophic oceans.

200 North Aggregate Area source AAMS report

International Nuclear Information System (INIS)

1993-06-01

This report presents the results of an aggregate area management study (AAMS) for the 200 North Aggregate Area in the 200 Areas of the US Department of Energy (DOE) Hanford Site in Washington State. This scoping level study provides the basis for initiating Remedial Investigation/Feasibility Study (RI/FS) activities under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) or Resource Conservation and Recovery Act (RCRA) Facility Investigations (RFI) and Corrective Measures Studies (CMS) under RCRA. This report also integrates select RCRA treatment, storage, or disposal (TSD) closure activities with CERCLA and RCRA past practice investigations

PUREX source Aggregate Area management study report

International Nuclear Information System (INIS)

1993-03-01

This report presents the results of an aggregate area management study (AAMS) for the PUREX Plant Aggregate Area in the 200 Areas of the US Department of Energy (DOE)Hanford Site in Washington State. This scoping level study provides the basis for initiating Remedial Investigation/Feasibility Study (RI/FS) activities under the comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) or Resource Conservation and Recovery Act (RCRA) Facility Investigations (RFI) and Corrective Measures Studies (CMS) under RCRA. This report also integrates select RCRA treatment, storage, or disposal (TSD) closure activities with CERCLA and RCRA past-practice investigations

200 North Aggregate Area source AAMS report

Energy Technology Data Exchange (ETDEWEB)

1993-06-01

This report presents the results of an aggregate area management study (AAMS) for the 200 North Aggregate Area in the 200 Areas of the US Department of Energy (DOE) Hanford Site in Washington State. This scoping level study provides the basis for initiating Remedial Investigation/Feasibility Study (RI/FS) activities under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) or Resource Conservation and Recovery Act (RCRA) Facility Investigations (RFI) and Corrective Measures Studies (CMS) under RCRA. This report also integrates select RCRA treatment, storage, or disposal (TSD) closure activities with CERCLA and RCRA past practice investigations.

Use of Crushed Granite Fine as Replacement to River Sand in Concrete Production

Directory of Open Access Journals (Sweden)

Manasseh JOEL

2010-12-01

Full Text Available The suitability of Crushed granite fine (CGF to replace river sand in concrete production for use in rigid pavement was investigated. Slump, compressive and indirect tensile strength tests were performed on fresh and hardened concrete.28 days Peak compressive and indirect tensile strength values of 40.70N/mm2 and 2.30N/mm2 respectively was obtained, with the partial replacement of river sand with 20% CGF, as against values of 35.00N/mm2 and 1.75N/mm2, obtained with the use of river sand as fine aggregate. Based on economic analysis and results of tests, river sand replaced with 20% CGF is recommended for use in the production of concrete for use in rigid pavement. Conservation of river sand in addition to better ways of disposing wastes from the quarry sites are some of the merits of using CGF.

A Factorial Design Approach to Analyse the Effect of Coarse Recycled Concrete Aggregates on the Properties of Hot Mix Asphalt

Science.gov (United States)

Tanty, Kiranbala; Mukharjee, Bibhuti Bhusan; Das, Sudhanshu Shekhar

2018-02-01

The present study investigates the effect of replacement of coarse fraction of natural aggregates by recycled concrete aggregates on the properties of hot mix asphalt (HMA) using general factorial design approach. For this two factors i.e. recycled coarse aggregates percentage [RCA (%)] and bitumen content percentage [BC (%)] are considered. Tests have been carried out on the HMA type bituminous concrete, prepared with varying RCA (%) and BC (%). Analysis of variance has been performed on the experimental data to determine the effect of the chosen factors on various parameters such as stability, flow, air void, void mineral aggregate, void filled with bitumen and bulk density. The study depicts that RCA (%) and BC (%) have significant effect on the selected responses as p value is less than the chosen significance level. In addition to above, the outcomes of the statistical analysis indicate that interaction between factors have significant effects on void mineral aggregate and bulk density of bituminous concrete.

A Factorial Design Approach to Analyse the Effect of Coarse Recycled Concrete Aggregates on the Properties of Hot Mix Asphalt

Science.gov (United States)

Tanty, Kiranbala; Mukharjee, Bibhuti Bhusan; Das, Sudhanshu Shekhar

2018-06-01

The present study investigates the effect of replacement of coarse fraction of natural aggregates by recycled concrete aggregates on the properties of hot mix asphalt (HMA) using general factorial design approach. For this two factors i.e. recycled coarse aggregates percentage [RCA (%)] and bitumen content percentage [BC (%)] are considered. Tests have been carried out on the HMA type bituminous concrete, prepared with varying RCA (%) and BC (%). Analysis of variance has been performed on the experimental data to determine the effect of the chosen factors on various parameters such as stability, flow, air void, void mineral aggregate, void filled with bitumen and bulk density. The study depicts that RCA (%) and BC (%) have significant effect on the selected responses as p value is less than the chosen significance level. In addition to above, the outcomes of the statistical analysis indicate that interaction between factors have significant effects on void mineral aggregate and bulk density of bituminous concrete.

Influence of the aggregate state on band structure and optical properties of C60 computed with different methods

Science.gov (United States)

Pal, Amrita; Arabnejad, Saeid; Yamashita, Koichi; Manzhos, Sergei

2018-05-01

C60 and C60 based molecules are efficient acceptors and electron transport layers for planar perovskite solar cells. While properties of these molecules are well studied by ab initio methods, those of solid C60, specifically its optical absorption properties, are not. We present a combined density functional theory-Density Functional Tight Binding (DFTB) study of the effect of solid state packing on the band structure and optical absorption of C60. The valence and conduction band edge energies of solid C60 differ on the order of 0.1 eV from single molecule frontier orbital energies. We show that calculations of optical properties using linear response time dependent-DFT(B) or the imaginary part of the dielectric constant (dipole approximation) can result in unrealistically large redshifts in the presence of intermolecular interactions compared to available experimental data. We show that optical spectra computed from the frequency-dependent real polarizability can better reproduce the effect of C60 aggregation on optical absorption, specifically with a generalized gradient approximation functional, and may be more suited to study effects of molecular aggregation.

Utilising Fine and Coarse Recycled Aggregates from the Gulf Region in Concrete

Science.gov (United States)

Jones, M. Rod; Halliday, Judith E.; Csetenyi, Laszlo; Zheng, Li; Strompinis, N.

This paper explores the feasibility in utilising materials generated from C&DW to produce a `green' concrete. The two materials that are considered here are, (i) up-sizing silt-size material generated from recycled aggregates to produce a synthetic silt-sand and (ii) processed recycled coarse aggregates (RA) sourced from a Gulf Region landfill site. The work has demonstrated that there is potential for utilising silt wastes into foamed concrete, which can then be crushed to a sand-sized material suitable for use in concrete, however the porous nature of the material has highlighted that the water demand of this RA is high. RAs were characterised to BS EN 12620 and found suitable for use in concrete. The effect of RA on concrete properties is minimal when used up to 35% replacement levels, provided that they are pre-soaked.

Defining and systematic analyses of aggregation indices to evaluate degree of calcium oxalate crystal aggregation

Science.gov (United States)

Chaiyarit, Sakdithep; Thongboonkerd, Visith

2017-12-01

Crystal aggregation is one of the most crucial steps in kidney stone pathogenesis. However, previous studies of crystal aggregation were rarely done and quantitative analysis of aggregation degree was handicapped by a lack of the standard measurement. We thus performed an in vitro assay to generate aggregation of calcium oxalate monohydrate (COM) crystals with various concentrations (25-800 µg/ml) in saturated aggregation buffer. The crystal aggregates were analyzed by microscopic examination, UV-visible spectrophotometry, and GraphPad Prism6 software to define a total of 12 aggregation indices (including number of aggregates, aggregated mass index, optical density, aggregation coefficient, span, number of aggregates at plateau time-point, aggregated area index, aggregated diameter index, aggregated symmetry index, time constant, half-life, and rate constant). The data showed linear correlation between crystal concentration and almost all of these indices, except only for rate constant. Among these, number of aggregates provided the greatest regression coefficient (r=0.997; pr=0.993; pr=‑0.993; pr=0.991; p<0.001 for both). These five indices are thus recommended as the most appropriate indices for quantitative analysis of COM crystal aggregation in vitro.

Geometrical Aspects During Formation of Compact Aggregates of Red Blood Cells

Directory of Open Access Journals (Sweden)

Cardoso A.V.

2002-01-01

Full Text Available In the past forty years considerable progress has been achieved on the knowledge of human blood as a non-Newtonian shear-thinning suspension, whose initial state, that is at rest (stasis or at very low shear rates, has a gel-like internal structure which is destroyed as shear stress increases. The main goal of this communication is to describe the role of geometrical aspects during RBC (red blood cell aggregate formation, growth and compaction on naturally aggregate (porcine blood and non-aggregate (bovine blood samples. We consider how these aspects coupled with tension equilibrium are decisive to transform red cell linear roleaux to three-dimensional aggregates or clusters. Geometrical aspects are also crucial on the compaction of red blood cell aggregates. These densely packed aggregates could precipitate out of blood- either as dangerous deposits on arterial walls, or as clots which travel in suspension until they block some crucial capillary.

Sustainable aggregates production : green applications for aggregate by-products.

Science.gov (United States)

2015-06-01

Increased emphasis in the construction industry on sustainability and recycling requires production of : aggregate gradations with lower dust (cleaner aggregates) and smaller maximum sizeshence, increased : amount of quarry by-products (QBs). QBs ...

Aggregated Dispatch of Distributed Generation Units: Final Report

Energy Technology Data Exchange (ETDEWEB)

2004-09-01

This final report describes a project to demonstrate the technical and economic feasibility of aggregating distributed generating resources in New York State. This project demonstrates a system that allows distributed generation (DG) to participate in competitive markets in much the same way as large central-station power plants. This approach involves aggregating the distributed demand-side resources into a single transaction entity consistent with the requirements of the New York Independent System Operator (NYISO). This single entity then buys or sells capacity and energy (i.e., curtailment) in NYISO markets.

{beta}-Carotene to bacteriochlorophyll c energy transfer in self-assembled aggregates mimicking chlorosomes

Energy Technology Data Exchange (ETDEWEB)

Alster, J. [Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Praha (Czech Republic); Polivka, T. [Institute of Physical Biology, University of South Bohemia, Zamek 136, 373 33 Nove Hrady (Czech Republic); Biology Centre, Academy of Sciences of the Czech Republic, Branisovska 31, 370 05 Ceske Budejovice (Czech Republic); Arellano, J.B. [Instituto de Recursos Naturales y Agrobiologia de Salamanca (IRNASA-CSIC), Apdo. 257, 37071 Salamanca (Spain); Chabera, P. [Institute of Physical Biology, University of South Bohemia, Zamek 136, 373 33 Nove Hrady (Czech Republic); Vacha, F. [Institute of Physical Biology, University of South Bohemia, Zamek 136, 373 33 Nove Hrady (Czech Republic); Biology Centre, Academy of Sciences of the Czech Republic, Branisovska 31, 370 05 Ceske Budejovice (Czech Republic); Psencik, J., E-mail: psencik@karlov.mff.cuni.cz [Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Praha (Czech Republic); Institute of Physical Biology, University of South Bohemia, Zamek 136, 373 33 Nove Hrady (Czech Republic)

2010-07-19

Carotenoids are together with bacteriochlorophylls important constituents of chlorosomes, the light-harvesting antennae of green photosynthetic bacteria. Majority of bacteriochlorophyll molecules form self-assembling aggregates inside the chlorosomes. Aggregates of bacteriochlorophylls with optical properties similar to those of chlorosomes can also be prepared in non-polar organic solvents or in aqueous environments when a suitable non-polar molecule is added. In this work, the ability of {beta}-carotene to induce aggregation of bacteriochlorophyll c in aqueous buffer was studied. Excitation relaxation and energy transfer in the carotenoid-bacteriochlorophyll assemblies were measured using femtosecond and nanosecond transient absorption spectroscopy. A fast, {approx}100-fs energy transfer from the S{sub 2} state of {beta}-carotene to bacteriochlorophyll c was revealed, while no evidence for significant energy transfer from the S{sub 1} state was found. Picosecond formation of the carotenoid triplet state (T{sub 1}) was observed, which was likely generated by singlet homo-fission from the S{sub 1} state of {beta}-carotene.

Epicrystal modification of construction composites of different purpose with application of granulated nanostructured aggregate

Directory of Open Access Journals (Sweden)

STROKOVA Valeria Valerievna

2016-10-01

Full Text Available The paper shows that the volume impregnation of the concrete matrix in case of using granular nanostructured aggregate is an example of several anthropogenic metasomatosis such as phase replacement with the change of the chemical composition, as well as formation of new paragenesises, transformation of characteristics of final material. It is shown the impregnation of concrete with modifying solution results in microstructure impaction and homogenization; grain surface is covered with micro- and nano-sized new formations with different morphology. Considering the relevance of researches related to the development of new lightweight concrete aggregates and modification of traditionally used aggregates application of nanostructured granular aggregate for the implementation epicrystal modification of lightweight concrete based on inorganic binders is proposed. It allows creating composite macroporous structure with joint modification of the matrix on nano- and microlevel. Also, in view of increase in number of researches devoted to alkali-activated silicate and aluminosilicate systems for application as individually and as modifiers for increasing of hydrophobic properties of building materials, the possibility of creating a fine-grained concrete with low water absorption by the introduction of hydrophobic additives into the composition of granular nanostructured aggregate is demonstrated. During the steam treatment the fluids from solutions of sodium polysilicates and hydrophobic additives are form at the core of the granular aggregate with its later migration through the shell of the granules and spreading in the volume of the concrete matrix. Improving of performance characteristics presented construction composites for various purposes is defined by the infiltrational metasomatic transformation of crystalline matrix with the activated functional systems, obtained during the thermal activation of granulated nanostructured aggregate.

Modeling capsid kinetics assembly from the steady state distribution of multi-sizes aggregates

Energy Technology Data Exchange (ETDEWEB)

Hozé, Nathanaël; Holcman, David

2014-01-24

The kinetics of aggregation for particles of various sizes depends on their diffusive arrival and fusion at a specific nucleation site. We present here a mean-field approximation and a stochastic jump model for aggregates at equilibrium. This approach is an alternative to the classical Smoluchowski equations that do not have a close form and are not solvable in general. We analyze these mean-field equations and obtain the kinetics of a cluster formation. Our approach provides a simplified theoretical framework to study the kinetics of viral capsid formation, such as HIV from the self-assembly of the structural proteins Gag.

Influence of Aggregate Wettability with Different Lithology Aggregates on Concrete Drying Shrinkage

Directory of Open Access Journals (Sweden)

Yuanchen Guo

2015-01-01

Full Text Available The correlation of the wettability of different lithology aggregates and the drying shrinkage of concrete materials is studied, and some influential factors such as wettability and wetting angle are analyzed. A mercury porosimeter is used to measure the porosities of different lithology aggregates accurately, and the pore size ranges that significantly affect the drying shrinkage of different lithology aggregate concretes are confirmed. The pore distribution curve of the different coarse aggregates is also measured through a statistical method, and the contact angle of different coarse aggregates and concrete is calculated according to the linear fitting relationship. Research shows that concrete strength is determined by aggregate strength. Aggregate wettability is not directly correlated with concrete strength, but wettability significantly affects concrete drying shrinkage. In all types’ pores, the greatest impacts on wettability are capillary pores and gel pores, especially for the pores of the size locating 2.5–50 nm and 50–100 nm two ranges.

Statistical mixing and aggregation in Feller diffusion

International Nuclear Information System (INIS)

Anteneodo, C; Duarte Queirós, S M

2009-01-01

We consider Feller mean-reverting square-root diffusion, which has been applied to model a wide variety of processes with linearly state-dependent diffusion, such as stochastic volatility and interest rates in finance, and neuronal and population dynamics in the natural sciences. We focus on the statistical mixing (or superstatistical) process in which the parameter related to the mean value can fluctuate—a plausible mechanism for the emergence of heavy-tailed distributions. We obtain analytical results for the associated probability density function (both stationary and time-dependent), its correlation structure and aggregation properties. Our results are applied to explain the statistics of stock traded volume at different aggregation scales

Performance of Reinforced Concrete Beam with Differently Positioned Replacement Zones of Block Infill under Low Impact Loads

Directory of Open Access Journals (Sweden)

Mokhatar Shahrul Niza

2017-01-01

Full Text Available This paper reveals a study performed on reinforced concrete with artificial aggregate concrete block infill composite beams to innovate a lightweight reinforced concrete utilizing polyethylene (PE waste materials, such as waste plastic bags. Six beam specimens of normal reinforced concrete (NRC and different block infill replacement zone positions RCAI (RZ1 beams containing 100% MAPEA with 50, 95, and 1,000 mm width, height, and length, respectively, were provided for the block infill, whereas RCAI (RZ2 with different block infill positions containing a 100% MAPEA with 50, 115, and 1000 mm width, height, and length were provided and tested under low impact load. The steel impactor with blunt nose dropped at 0.6 m height which equivalent to 3.5 m/s. The behaviors of the beams were studied relative to the impact force-time and displacement-time histories, the flexural/ bending cracks, and the impact failure. Results show that the overall failure modes of all the beam specimens were successfully recorded. In addition, the residual displacements of the RZ2 was almost same than those of the RZ1 and the significantly lower than those of the NRC. In the reinforced concrete beams, less stressed concrete near the neutral axis can be replaced by certain light weight material like waste plastic bags as modified artificial polyethylene aggregates to serve as an artificial aggregate.

RELATIONSHIPS BETWEEN SOIL MICROBIAL BIOMASS, AGGREGATE STABILITY AND AGGREGATE ASSOCIATED-C: A MECHANISTIC APPROACH

Directory of Open Access Journals (Sweden)

Patrizia Guidi

2014-01-01

Full Text Available For the identification of C pools involved in soil aggregation, a physically-based aggregate fractionation was proposed, and  additional pretreatments were used in the measurement of the 1-2 mm aggregate stability in order to elucidate the relevance of the role of soil microorganisms with respect to the different aggregate breakdown mechanisms. The study was carried out on three clay loam Regosols, developed on calcareous shales, known history of organic cultivation.Our results showed that the soil C pool controlling the process of stabilisation of aggregates was related to the microbial community. We identified the resistance to fast wetting as the major mechanism of aggregate stability driven by microorganims. The plausible hypothesis is that organic farming promotes fungi growth, improving water repellency of soil aggregates by fungal hydrophobic substances. By contrast, we failed in the identification of C pools controlling the formation of aggregates, probably because of the disturbance of mechanical tillage which contributes to the breakdown of soil aggregates.The physically-based aggregate fractionation proposed in this study resulted useful in the  mechanistically understanding of the role of microorganisms in soil aggregation and it might be suggested for studying the impact of management on C pools, aggregates properties and their relationships in agricultural soils.

Light scattering method to measure red blood cell aggregation during incubation

Science.gov (United States)

Grzegorzewski, B.; Szołna-Chodór, A.; Baryła, J.; DreŻek, D.

2018-01-01

Red blood cell (RBC) aggregation can be observed both in vivo as well as in vitro. This process is a cause of alterations of blood flow in microvascular network. Enhanced RBC aggregation makes oxygen and nutrients delivery difficult. Measurements of RBC aggregation usually give a description of the process for a sample where the state of a solution and cells is well-defined and the system reached an equilibrium. Incubation of RBCs in various solutions is frequently used to study the effects of the solutions on the RBC aggregation. The aggregation parameters are compared before and after incubation while the detailed changes of the parameters during incubation remain unknown. In this paper we have proposed a method to measure red blood cell aggregation during incubation based on the well-known technique where backscattered light is used to assess the parameters of the RBC aggregation. Couette system consisting of two cylinders is adopted in the method. The incubation is observed in the Couette system. In the proposed method following sequence of rotations is adapted. Two minutes rotation is followed by two minutes stop. In this way we have obtained a time series of back scattered intensity consisting of signals respective for disaggregation and aggregation. It is shown that the temporal changes of the intensity manifest changes of RBC aggregation during incubation. To show the ability of the method to assess the effect of incubation time on RBC aggregation the results are shown for solutions that cause an increase of RBC aggregation as well as for the case where the aggregation is decreased.

HST Replacement Battery Initial Performance

Science.gov (United States)

Krol, Stan; Waldo, Greg; Hollandsworth, Roger

2009-01-01

The Hubble Space Telescope (HST) original Nickel-Hydrogen (NiH2) batteries were replaced during the Servicing Mission 4 (SM4) after 19 years and one month on orbit.The purpose of this presentation is to highlight the findings from the assessment of the initial sm4 replacement battery performance. The batteries are described, the 0 C capacity is reviewed, descriptions, charts and tables reviewing the State Of Charge (SOC) Performance, the Battery Voltage Performance, the battery impedance, the minimum voltage performance, the thermal performance, the battery current, and the battery system recharge ratio,

Self-Aggregation in Pyrrole:  Matrix Isolation, Solid State Infrared Spectroscopy, and DFT Study

OpenAIRE

Gómez-Zavaglia, Andrea; Fausto, Rui

2004-01-01

Pyrrole (C4H5N) was embedded in low-temperature solid inert matrixes (argon, xenon; T = 9 K) and both the monomer and low-order aggregates characterized by FTIR spectroscopy. The spectroscopic studies were complemented by extensive theoretical [DFT(B3LYP)/6-311++G(d,p)] structural and vibrational studies carried out for the monomer and their self-aggregates (up to four units). The calculated spectrum for monomeric pyrrole fits well those obtained immediately after deposition (at 9 K) of dilut...

Innovative Solid State Lighting Replacements for Industrial and Test Facility Locations, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The proposed innovation is the replacement of existing test stand and parking lot fixtures with current SSL LED technology. The replacement fixtures will reduce...

X-ray studies on crystalline complexes involving amino acids and peptides. XXXII. Effect of chirality on ionisation state, stoichiometry and aggregation in the complexes of oxalic acid with DL- and L-lysine.

Science.gov (United States)

Venkatraman, J; Prabu, M M; Vijayan, M

1997-08-01

Crystals of the oxalic acid complex of DL-lysine (triclinic P1; a = 5.540(1), b = 10.764(2), c = 12.056(2) A, alpha = 77.8(1), beta = 80.6(1), gamma = 75.6(1).; R = 4.7% for 2023 observed reflections) contain lysine and semioxalate ions in the 1:1 ratio, whereas the ratio of lysine and semioxalate/oxalate ions is 2:3 in the crystals of the L-lysine complex (monoclinic P2(1); alpha = 4.906(1), b = 20.145(4), c = 12.455(1) A, beta = 92.5(1).; R = 4.4% for 1494 observed reflections). The amino acid molecule in the L-lysine complex has an unusual ionisation state with positively charged alpha- and side-chain amino groups and a neutral carboxyl group. The unlike molecules aggregate into separate alternating layers in the DL-lysine complex in a manner similar to that observed in several of the amino acid complexes. The L-lysine complex exhibits a new aggregation pattern which cannot be easily explained in terms of planar features, thus emphasizing the fundamental dependence of aggregation on molecular characteristics. Despite the differences in stoichiometry, ionisation state and long-range aggregation patterns, the basic element of aggregation in the two complexes exhibits considerable similarity.

Effect of aggregate graining compositions on skid resistance of Exposed Aggregate Concrete pavement

Science.gov (United States)

Wasilewska, Marta; Gardziejczyk, Wladysław; Gierasimiuk, Pawel

2018-05-01

The paper presents the evaluation of skid resistance of EAC (Exposed Aggregate Concrete) pavements which differ in aggregate graining compositions. The tests were carried out on concrete mixes with a maximum aggregate size of 8 mm. Three types of coarse aggregates were selected depending on their resistance to polishing which was determined on the basis of the PSV (Polished Stone Value). Basalt (PSV 48), gabbro (PSV 50) and trachybasalt (PSV 52) aggregates were chosen. For each type of aggregate three graining compositions were designed, which differed in the content of coarse aggregate > 4mm. Their content for each series was as follows: A - 38%, B - 50% and C - 68%. Evaluation of the skid resistance has been performed using the FAP (Friction After Polishing) test equipment also known as the Wehner/Schulze machine. Laboratory method enables to compare the skid resistance of different types of wearing course under specified conditions simulating polishing processes. In addition, macrotexture measurements were made on the surface of each specimen using the Elatexure laser profile. Analysis of variance showed that at significance level α = 0.05, aggregate graining compositions as well as the PSV have a significant influence on the obtained values of the friction coefficient μm of the tested EAC pavements. The highest values of the μm have been obtained for EAC with the lowest amount of coarse aggregates (compositions A). In these cases the resistance to polishing of the aggregate does not significantly affect the friction coefficients. This is related to the large areas of cement mortar between the exposed coarse grains. Based on the analysis of microscope images, it was observed that the coarse aggregates were not sufficiently exposed. It has been proved that PSV significantly affected the coefficient of friction in the case of compositions B and C. This is caused by large areas of exposed coarse aggregate. The best parameters were achieved for the EAC pavements

30 CFR 872.29 - What are prior balance replacement funds?

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false What are prior balance replacement funds? 872... § 872.29 What are prior balance replacement funds? “Prior balance replacement funds” are moneys we must... general funds of the United States Treasury that are otherwise unappropriated. Under section 411(h)(1) of...

200 West Groundwater Aggregate Area management study report

International Nuclear Information System (INIS)

1993-01-01

This report presents the results of an aggregate area management study (AAMS) for the 200 West Groundwater Aggregate Area in the 200 Areas of the US Department of Energy (DOE) Hanford Site in Washington State. This scoping level study provides the basis for initiating Remedial Investigation/Feasibility Study (RI/FS) activities under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) or Resource Conservation and Recovery Act (RCRA), Facility Investigations (Rlq) and Corrective Measures Studies (CMS) under RCRA. This report also integrates select RCRA treatment, storage or disposal (TSD) closure activities with CERCLA and RCRA past practice investigations

Concrete produced with recycled aggregates

Directory of Open Access Journals (Sweden)

J. J. L. Tenório

Full Text Available This paper presents the analysis of the mechanical and durable properties of recycled aggregate concrete (RAC for using in concrete. The porosity of recycled coarse aggregates is known to influence the fresh and hardened concrete properties and these properties are related to the specific mass of the recycled coarse aggregates, which directly influences the mechanical properties of the concrete. The recycled aggregates were obtained from construction and demolition wastes (CDW, which were divided into recycled sand (fine and coarse aggregates. Besides this, a recycled coarse aggregate of a specific mass with a greater density was obtained by mixing the recycled aggregates of the CDW with the recycled aggregates of concrete wastes (CW. The concrete was produced in laboratory by combining three water-cement ratios, the ratios were used in agreement with NBR 6118 for structural concretes, with each recycled coarse aggregates and recycled sand or river sand, and the reference concrete was produced with natural aggregates. It was observed that recycled aggregates can be used in concrete with properties for structural concrete. In general, the use of recycled coarse aggregate in combination with recycled sand did not provide good results; but when the less porous was used, or the recycled coarse aggregate of a specific mass with a greater density, the properties of the concrete showed better results. Some RAC reached bigger strengths than the reference concrete.

Graph Aggregation

NARCIS (Netherlands)

Endriss, U.; Grandi, U.

Graph aggregation is the process of computing a single output graph that constitutes a good compromise between several input graphs, each provided by a different source. One needs to perform graph aggregation in a wide variety of situations, e.g., when applying a voting rule (graphs as preference

Identification of CLN6 as a molecular entity of endoplasmic reticulum-driven anti-aggregate activity.

Science.gov (United States)

Yamashita, Arisa; Hiraki, Yuri; Yamazaki, Tetsuo

2017-06-10

αB-crystallin (αBC) is a small heat shock protein. Mutations in the αBC gene are linked to α-crystallinopathy, a hereditary myopathy histologically characterized by intracellular accumulation of protein aggregates. The disease-causing R120G αBC mutant, harboring an arginine-to-glycine replacement at position 120, is an aggregate-prone protein. We previously showed that the R120G mutant's aggregation in HeLa cells was prevented by enforced expression of αBC on the endoplasmic reticulum (ER). To elucidate the molecular nature of the preventive effect on the R120G mutant, we isolated proteins binding to ER-anchored αBC (TMαBC). The ER transmembrane CLN6 protein was identified as a TMαBC's binder. CLN6 knockdown in HeLa cells attenuated TMαBC's anti-aggregate activity against the R120G mutant. Conversely, CLN6 overexpression enhanced the activity, indicating that CLN6 operates as a downstream effector of TMαBC. CLN6 physically interacted with the R120G mutant, and repressed its aggregation in HeLa cells even when TMαBC was not co-expressed. Furthermore, CLN6's antagonizing effect on the R120G mutant was compromised upon treatment with a lysosomal inhibitor, suggesting CLN6 requires the intact autophagy-lysosome system to prevent the R120G mutant from aggregating. We hence conclude that CLN6 is not only a molecular entity of the anti-aggregate activity conferred by the ER manipulation using TMαBC, but also serves as a potential target of therapeutic interventions. Copyright © 2017 Elsevier Inc. All rights reserved.

Predicting protein aggregation during storage in lyophilized solids using solid state amide hydrogen/deuterium exchange with mass spectrometric analysis (ssHDX-MS).

Science.gov (United States)

Moorthy, Balakrishnan S; Schultz, Steven G; Kim, Sherry G; Topp, Elizabeth M

2014-06-02

Solid state amide hydrogen/deuterium exchange with mass spectrometric analysis (ssHDX-MS) was used to assess the conformation of myoglobin (Mb) in lyophilized formulations, and the results correlated with the extent of aggregation during storage. Mb was colyophilized with sucrose (1:1 or 1:8 w/w), mannitol (1:1 w/w), or NaCl (1:1 w/w) or in the absence of excipients. Immediately after lyophilization, samples of each formulation were analyzed by ssHDX-MS and Fourier transform infrared spectroscopy (FTIR) to assess Mb conformation, and by dynamic light scattering (DLS) and size exclusion chromatography (SEC) to determine the extent of aggregation. The remaining samples were then placed on stability at 25 °C and 60% RH or 40 °C and 75% RH for up to 1 year, withdrawn at intervals, and analyzed for aggregate content by SEC and DLS. In ssHDX-MS of samples immediately after lyophilization (t = 0), Mb was less deuterated in solids containing sucrose (1:1 and 1:8 w/w) than in those containing mannitol (1:1 w/w), NaCl (1:1 w/w), or Mb alone. Deuterium uptake kinetics and peptide mass envelopes also indicated greater Mb structural perturbation in mannitol, NaCl, or Mb-alone samples at t = 0. The extent of deuterium incorporation and kinetic parameters related to rapidly and slowly exchanging amide pools (Nfast, Nslow), measured at t = 0, were highly correlated with the extent of aggregation on storage as measured by SEC. In contrast, the extent of aggregation was weakly correlated with FTIR band intensity and peak position measured at t = 0. The results support the use of ssHDX-MS as a formulation screening tool in developing lyophilized protein drug products.

p53 Aggregates penetrate cells and induce the co-aggregation of intracellular p53.

Directory of Open Access Journals (Sweden)

Karolyn J Forget

Full Text Available Prion diseases are unique pathologies in which the infectious particles are prions, a protein aggregate. The prion protein has many particular features, such as spontaneous aggregation, conformation transmission to other native PrP proteins and transmission from an individual to another. Protein aggregation is now frequently associated to many human diseases, for example Alzheimer's disease, Parkinson's disease or type 2 diabetes. A few proteins associated to these conformational diseases are part of a new category of proteins, called prionoids: proteins that share some, but not all, of the characteristics associated with prions. The p53 protein, a transcription factor that plays a major role in cancer, has recently been suggested to be a possible prionoid. The protein has been shown to accumulate in multiple cancer cell types, and its aggregation has also been reproduced in vitro by many independent groups. These observations suggest a role for p53 aggregates in cancer development. This study aims to test the «prion-like» features of p53. Our results show in vitro aggregation of the full length and N-terminally truncated protein (p53C, and penetration of these aggregates into cells. According to our findings, the aggregates enter cells using macropinocytosis, a non-specific pathway of entry. Lastly, we also show that once internalized by the cell, p53C aggregates can co-aggregate with endogenous p53 protein. Together, these findings suggest prion-like characteristics for p53 protein, based on the fact that p53 can spontaneously aggregate, these aggregates can penetrate cells and co-aggregate with cellular p53.

Solid-state NMR analysis of membrane proteins and protein aggregates by proton detected spectroscopy

International Nuclear Information System (INIS)

Zhou, Donghua H.; Nieuwkoop, Andrew J.; Berthold, Deborah A.; Comellas, Gemma; Sperling, Lindsay J.; Tang, Ming; Shah, Gautam J.; Brea, Elliott J.; Lemkau, Luisel R.; Rienstra, Chad M.

2012-01-01

Solid-state NMR has emerged as an important tool for structural biology and chemistry, capable of solving atomic-resolution structures for proteins in membrane-bound and aggregated states. Proton detection methods have been recently realized under fast magic-angle spinning conditions, providing large sensitivity enhancements for efficient examination of uniformly labeled proteins. The first and often most challenging step of protein structure determination by NMR is the site-specific resonance assignment. Here we demonstrate resonance assignments based on high-sensitivity proton-detected three-dimensional experiments for samples of different physical states, including a fully-protonated small protein (GB1, 6 kDa), a deuterated microcrystalline protein (DsbA, 21 kDa), a membrane protein (DsbB, 20 kDa) prepared in a lipid environment, and the extended core of a fibrillar protein (α-synuclein, 14 kDa). In our implementation of these experiments, including CONH, CO(CA)NH, CANH, CA(CO)NH, CBCANH, and CBCA(CO)NH, dipolar-based polarization transfer methods have been chosen for optimal efficiency for relatively high protonation levels (full protonation or 100 % amide proton), fast magic-angle spinning conditions (40 kHz) and moderate proton decoupling power levels. Each H–N pair correlates exclusively to either intra- or inter-residue carbons, but not both, to maximize spectral resolution. Experiment time can be reduced by at least a factor of 10 by using proton detection in comparison to carbon detection. These high-sensitivity experiments are especially important for membrane proteins, which often have rather low expression yield. Proton-detection based experiments are expected to play an important role in accelerating protein structure elucidation by solid-state NMR with the improved sensitivity and resolution.

Fulfilment of knowledge expectations and emotional state among people undergoing hip replacement: a multi-national survey.

Science.gov (United States)

Johansson Stark, Asa; Ingadottir, Brynja; Salanterä, Sanna; Sigurdardottir, Arun; Valkeapää, Kirsi; Bachrach-Lindström, Margareta; Unosson, Mitra

2014-11-01

Patient education in connection with hip replacement is intended to prepare patients for surgery, discharge and postoperative recovery. Patients experience symptoms and emotions due to disease or upcoming surgery which can affect how their knowledge expectations are fulfilled. To describe the differences between received and expected knowledge in patients undergoing elective hip replacement in three Nordic countries, and to analyse how these differences are related to patients' characteristics, preoperative symptoms and emotions. A descriptive, prospective survey with two data collection points; before admission and at hospital discharge after surgery. Two Finnish, three Icelandic and two Swedish hospitals. The population consisted of patients on a waiting list for hip replacement. Of the consecutively included patients, 320 answered questionnaires both before admission and at discharge and were included in the study. The mean age of the patients was 64 years, and 55% were women. Structured questionnaires were used; the knowledge expectations of hospital patients scale and self-reported scales for symptoms and emotions before admission and received knowledge of hospital patients scale at discharge. Fulfilment of knowledge expectation was assessed by calculating the difference between received and expected knowledge with a paired sample t-test. A multiple stepwise regression model was used to explain the variance of fulfilled knowledge expectations. Patients expected more knowledge than they received (p<0.001) and 77% of them had unfulfilled knowledge expectations. Patients with a higher level of education were more likely to have unfulfilled knowledge expectations. A higher level of education was also related to a greater difference between received and expected knowledge. The difference was more correlated with patients' emotions than their symptoms. A depressive state was the major predictor of the variance in the difference between received and expected

Dynamics of Symmetric Conserved Mass Aggregation Model on Complex Networks

Institute of Scientific and Technical Information of China (English)

HUA Da-Yin

2009-01-01

We investigate the dynamical behaviour of the aggregation process in the symmetric conserved mass aggregation model under three different topological structures. The dispersion σ(t, L) = (∑i(mi - ρ0)2/L)1/2 is defined to describe the dynamical behaviour where ρ0 is the density of particle and mi is the particle number on a site. It is found numerically that for a regular lattice and a scale-free network, σ(t, L) follows a power-law scaling σ(t, L) ～ tδ1 and σ(t, L) ～ tδ4 from a random initial condition to the stationary states, respectively. However, for a small-world network, there are two power-law scaling regimes, σ(t, L) ～ tδ2 when t＜T and a(t, L) ～ tδ3 when tT. Moreover, it is found numerically that δ2 is near to δ1 for small rewiring probability q, and δ3 hardly changes with varying q and it is almost the same as δ4. We speculate that the aggregation of the connection degree accelerates the mass aggregation in the initial relaxation stage and the existence of the long-distance interactions in the complex networks results in the acceleration of the mass aggregation when tT for the small-world networks. We also show that the relaxation time T follows a power-law scaling τ Lz and σ(t, L) in the stationary state follows a power-law σs(L) ～ Lσ for three different structures.

Cross-seeding of prions by aggregated α-synuclein leads to transmissible spongiform encephalopathy.

Directory of Open Access Journals (Sweden)

Elizaveta Katorcha

2017-08-01

Full Text Available Aggregation of misfolded proteins or peptides is a common feature of neurodegenerative diseases including Alzheimer's, Parkinson's, Huntington's, prion and other diseases. Recent years have witnessed a growing number of reports of overlap in neuropathological features that were once thought to be unique to only one neurodegenerative disorder. However, the origin for the overlap remains unclear. One possibility is that diseases with mixed brain pathologies might arise from cross-seeding of one amyloidogenic protein by aggregated states of unrelated proteins. In the current study we examined whether prion replication can be induced by cross-seeding by α-synuclein or Aβ peptide. We found that α-synuclein aggregates formed in cultured cells or in vitro display cross-seeding activity and trigger misfolding of the prion protein (PrPC in serial Protein Misfolding Cyclic Amplification reactions, producing self-replicating PrP states characterized by a short C-terminal proteinase K (PK-resistant region referred to as PrPres. Non-fibrillar α-synuclein or fibrillar Aβ failed to cross-seed misfolding of PrPC. Remarkably, PrPres triggered by aggregated α-synuclein in vitro propagated in animals and, upon serial transmission, produced PrPSc and clinical prion disease characterized by spongiosis and astrocytic gliosis. The current study demonstrates that aggregated α-synuclein is potent in cross-seeding of prion protein misfolding and aggregation in vitro, producing self-replicating states that can lead to transmissible prion diseases upon serial passaging in wild type animals. In summary, the current work documents direct cross-seeding between unrelated amyloidogenic proteins associated with different neurodegenerative diseases. This study suggests that early interaction between unrelated amyloidogenic proteins might underlie the etiology of mixed neurodegenerative proteinopathies.

Multilevel LMDI decomposition of changes in aggregate energy consumption. A cross country analysis in the EU-27

International Nuclear Information System (INIS)

Fernández González, P.; Landajo, M.; Presno, M.J.

2014-01-01

This paper aims at analysing the factors behind the change in aggregate energy consumption in the EU-27, also identifying differences between member states. The logarithmic-mean Divisia index method (LMDI) is applied to multiplicatively decompose, at the country level, the variation in aggregate energy consumption in the EU-27 member states for the 2001–2008 period. We also analyse the sensitivity of the results when several aggregation levels are considered, with energy intensity used as the criterion to aggregate countries. This allows us to check robustness of results, also enabling an improved understanding of both inter and intra-unit effects. Results indicate that improvements in energy efficiency in the EU-27 were not enough to overcome the pressure of European economic activity on aggregate energy consumption. Mediterranean countries, and especially former communist states, increased their energy consumptions, most of them favoured by structural change. The analysis also reveals that the impact of intra-group movements on aggregate energy consumption is partially offset when moving from higher to lower aggregation levels. - Highlights: • Increase in EU-27 aggregate energy consumption is decomposed through LMDI at 3 levels. • We present the subgroup activity effect and we demonstrate its nulls consequences. • Structural and intensity group effects lose influence when moving to a higher level. • R and D, quality energies, efficient technologies, are main tools to lower energy consumption. • Structural effect: “Green” attitudes and changes in consumer choices, also necessary

Flocculation kinetics and aggregate structure of kaolinite mixtures in laminar tube flow.

Science.gov (United States)

Vaezi G, Farid; Sanders, R Sean; Masliyah, Jacob H

2011-03-01

Flocculation is commonly used in various solid-liquid separation processes in chemical and mineral industries to separate desired products or to treat waste streams. This paper presents an experimental technique to study flocculation processes in laminar tube flow. This approach allows for more realistic estimation of the shear rate to which an aggregate is exposed, as compared to more complicated shear fields (e.g. stirred tanks). A direct sampling method is used to minimize the effect of sampling on the aggregate structure. A combination of aggregate settling velocity and image analysis was used to quantify the structure of the aggregate. Aggregate size, density, and fractal dimension were found to be the most important aggregate structural parameters. The two methods used to determine aggregate fractal dimension were in good agreement. The effects of advective flow through an aggregate's porous structure and transition-regime drag coefficient on the evaluation of aggregate density were considered. The technique was applied to investigate the flocculation kinetics and the evolution of the aggregate structure of kaolin particles with an anionic flocculant under conditions similar to those of oil sands fine tailings. Aggregates were formed using a well controlled two-stage aggregation process. Detailed statistical analysis was performed to investigate the establishment of dynamic equilibrium condition in terms of aggregate size and density evolution. An equilibrium steady state condition was obtained within 90 s of the start of flocculation; after which no further change in aggregate structure was observed. Although longer flocculation times inside the shear field could conceivably cause aggregate structure conformation, statistical analysis indicated that this did not occur for the studied conditions. The results show that the technique and experimental conditions employed here produce aggregates having a well-defined, reproducible structure. Copyright © 2011

Aggregation of MBP in chronic demyelination.

Science.gov (United States)

Frid, Kati; Einstein, Ofira; Friedman-Levi, Yael; Binyamin, Orli; Ben-Hur, Tamir; Gabizon, Ruth

2015-07-01

Misfolding of key disease proteins to an insoluble state is associated with most neurodegenerative conditions, such as prion, Parkinson, and Alzheimer's diseases. In this work, and by studying animal models of multiple sclerosis, we asked whether this is also the case for myelin basic protein (MBP) in the late and neurodegenerative phases of demyelinating diseases. To this effect, we tested whether MBP, an essential myelin component, present prion-like properties in animal models of MS, as is the case for Cuprizone-induced chronic demyelination or chronic phases of Experimental Autoimmune Encephalomyelitis (EAE). We show here that while total levels of MBP were not reduced following extensive demyelination, part of these molecules accumulated thereafter as aggregates inside oligodendrocytes or around neuronal cells. In chronic EAE, MBP precipitated concomitantly with Tau, a marker of diverse neurodegenerative conditions, including MS. Most important, analysis of fractions from Triton X-100 floatation gradients suggest that the lipid composition of brain membranes in chronic EAE differs significantly from that of naïve mice, an effect which may relate to oxidative insults and subsequently prevent the appropriate insertion and compaction of new MBP in the myelin sheath, thereby causing its misfolding and aggregation. Prion-like aggregation of MBP following chronic demyelination may result from an aberrant lipid composition accompanying this pathological status. Such aggregation of MBP may contribute to neuronal damage that occurs in the progressive phase of MS.

Information Aggregation in Organizations

OpenAIRE

Schulte, Elisabeth

2006-01-01

This dissertation contributes to the analysis of information aggregation procedures within organizations. Facing uncertainty about the consequences of a collective decision, information has to be aggregated before making a choice. Two main questions are addressed. Firstly, how well is an organization suited for the aggregation of decision-relevant information? Secondly, how should an organization be designed in order to aggregate information efficiently? The main part deals with information a...

COMPARISON OF SIMPLE SUM AND DIVISIA MONETARY AGGREGATES USING PANEL DATA ANALYSIS

Directory of Open Access Journals (Sweden)

Sadullah CELIK

2009-07-01

Full Text Available It is well documented that financial innovation has led to poor performance of simple sum method of monetary aggregation destabilizing the historical relationship between monetary aggregates and ultimate target variables like rate of growth and rate of unemployment during the liberalization period of 1980s. This study tries to emphasize the superiority of an alternative method of aggregation over the simple sum method, namely Divisia monetary aggregates, employing panel data analysis for United States, United Kingdom, Euro Area and Japan for the period between 1980Q1 and 1993Q3. After investigating the order of stationarity of the panel data set through several panel unit root tests, we perform advanced panel cointegration tests to check the existence of a long run link between the Divisia monetary aggregates and income and interest rates in a simple Keynesian money demand function.

Cellular Models of Aggregation-dependent Template-directed Proteolysis to Characterize Tau Aggregation Inhibitors for Treatment of Alzheimer Disease.

Science.gov (United States)

Harrington, Charles R; Storey, John M D; Clunas, Scott; Harrington, Kathleen A; Horsley, David; Ishaq, Ahtsham; Kemp, Steven J; Larch, Christopher P; Marshall, Colin; Nicoll, Sarah L; Rickard, Janet E; Simpson, Michael; Sinclair, James P; Storey, Lynda J; Wischik, Claude M

2015-04-24

Alzheimer disease (AD) is a degenerative tauopathy characterized by aggregation of Tau protein through the repeat domain to form intraneuronal paired helical filaments (PHFs). We report two cell models in which we control the inherent toxicity of the core Tau fragment. These models demonstrate the properties of prion-like recruitment of full-length Tau into an aggregation pathway in which template-directed, endogenous truncation propagates aggregation through the core Tau binding domain. We use these in combination with dissolution of native PHFs to quantify the activity of Tau aggregation inhibitors (TAIs). We report the synthesis of novel stable crystalline leucomethylthioninium salts (LMTX®), which overcome the pharmacokinetic limitations of methylthioninium chloride. LMTX®, as either a dihydromesylate or a dihydrobromide salt, retains TAI activity in vitro and disrupts PHFs isolated from AD brain tissues at 0.16 μM. The Ki value for intracellular TAI activity, which we have been able to determine for the first time, is 0.12 μM. These values are close to the steady state trough brain concentration of methylthioninium ion (0.18 μM) that is required to arrest progression of AD on clinical and imaging end points and the minimum brain concentration (0.13 μM) required to reverse behavioral deficits and pathology in Tau transgenic mice. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Transcatheter Pulmonary Valve Replacement: Current State of Art.

Science.gov (United States)

Alkashkari, Wail; Alsubei, Amani; Hijazi, Ziyad M

2018-03-15

The past couple of decades have brought tremendous advances to the field of pediatric and adult congenital heart disease (CHD). Percutaneous valve interventions are now a cornerstone of not just the congenital cardiologist treating patients with congenital heart disease, but also-and numerically more importantly-for adult interventional cardiologists treating patients with acquired heart valve disease. Transcatheter pulmonary valve replacement (tPVR) is one of the most exciting recent developments in the treatment of CHD and has evolved to become an attractive alternative to surgery in patients with right ventricular outflow tract (RVOT) dysfunction. This review aims to summarize (1) the current state of the art for tPVR, (2) the expanding indications, and (3) the technological obstacles to optimizing tPVR. Since its introduction in 2000, more than ten thousands tPVR procedures have been performed worldwide. Although the indications for tPVR have been adapted earlier from those accepted for surgical intervention, they remain incompletely defined. The new imaging modalities give better assessment of cardiac anatomy and function and determine candidacy for the procedure. The procedure has been shown to be feasible and safe when performed in patients who received pulmonary conduit and or bioprosthetic valves between the right ventricle and the pulmonary artery. Fewer selected patients post trans-annular patch repair for tetralogy of Fallot may also be candidates for this technology. Size restrictions of the currently available valves limit deployment in the majority of patients post trans-annular patch repair. Newer valves and techniques are being developed that may help such patients. Refinements and further developments of this procedure hold promise for the extension of this technology to other patient populations.

A Novel Method to Quantify Soil Aggregate Stability by Measuring Aggregate Bond Energies

Science.gov (United States)

Efrat, Rachel; Rawlins, Barry G.; Quinton, John N.; Watts, Chris W.; Whitmore, Andy P.

2016-04-01

Soil aggregate stability is a key indicator of soil quality because it controls physical, biological and chemical functions important in cultivated soils. Micro-aggregates are responsible for the long term sequestration of carbon in soil, therefore determine soils role in the carbon cycle. It is thus vital that techniques to measure aggregate stability are accurate, consistent and reliable, in order to appropriately manage and monitor soil quality, and to develop our understanding and estimates of soil as a carbon store to appropriately incorporate in carbon cycle models. Practices used to assess the stability of aggregates vary in sample preparation, operational technique and unit of results. They use proxies and lack quantification. Conflicting results are therefore drawn between projects that do not provide methodological or resultant comparability. Typical modern stability tests suspend aggregates in water and monitor fragmentation upon exposure to an un-quantified amount of ultrasonic energy, utilising a laser granulometer to measure the change in mean weight diameter. In this project a novel approach has been developed based on that of Zhu et al., (2009), to accurately quantify the stability of aggregates by specifically measuring their bond energies. The bond energies are measured operating a combination of calorimetry and a high powered ultrasonic probe, with computable output function. Temperature change during sonication is monitored by an array of probes which enables calculation of the energy spent heating the system (Ph). Our novel technique suspends aggregates in heavy liquid lithium heteropolytungstate, as opposed to water, to avoid exposing aggregates to an immeasurable disruptive energy source, due to cavitation, collisions and clay swelling. Mean weight diameter is measured by a laser granulometer to monitor aggregate breakdown after successive periods of calculated ultrasonic energy input (Pi), until complete dispersion is achieved and bond

76 FR 30369 - Announcement of the Award of a Replacement Grant

Science.gov (United States)

2011-05-25

... the Award of a Replacement Grant AGENCY: Office of Community Services (OCS), ACF, DHHS. ACTION: Announcement of the award of a replacement grant from the Office of Community Services to Humboldt State... Services (OCS), announces the award of a replacement grant under the Strengthening Communities Fund (SCF...

Protein aggregation in bacteria: the thin boundary between functionality and toxicity.

Science.gov (United States)

Bednarska, Natalia G; Schymkowitz, Joost; Rousseau, Frederic; Van Eldere, Johan

2013-09-01

Misfolding and aggregation of proteins have a negative impact on all living organisms. In recent years, aggregation has been studied in detail due to its involvement in neurodegenerative diseases, including Alzheimer's, Parkinson's and Huntington's diseases, and type II diabetes--all associated with accumulation of amyloid fibrils. This research highlighted the central importance of protein homeostasis, or proteostasis for short, defined as the cellular state in which the proteome is both stable and functional. It implicates an equilibrium between synthesis, folding, trafficking, aggregation, disaggregation and degradation. In accordance with the eukaryotic systems, it has been documented that protein aggregation also reduces fitness of bacterial cells, but although our understanding of the cellular protein quality control systems is perhaps most detailed in bacteria, the use of bacterial proteostasis as a drug target remains little explored. Here we describe protein aggregation as a normal physiological process and its role in bacterial virulence and we shed light on how bacteria defend themselves against the toxic threat of aggregates. We review the impact of aggregates on bacterial viability and look at the ways that bacteria use to maintain a balance between aggregation and functionality. The proteostasis in bacteria can be interrupted via overexpression of proteins, certain antibiotics such as aminoglycosides, as well as antimicrobial peptides--all leading to loss of cell viability. Therefore intracellular protein aggregation and disruption of proteostatic balance in bacteria open up another strategy that should be explored towards the discovery of new antimicrobials.

Curcumin Attenuates Amyloid-β Aggregate Toxicity and Modulates Amyloid-β Aggregation Pathway.

Science.gov (United States)

Thapa, Arjun; Jett, Stephen D; Chi, Eva Y

2016-01-20

The abnormal misfolding and aggregation of amyloid-β (Aβ) peptides into β-sheet enriched insoluble deposits initiates a cascade of events leading to pathological processes and culminating in cognitive decline in Alzheimer's disease (AD). In particular, soluble oligomeric/prefibrillar Aβ have been shown to be potent neurotoxins. The naturally occurring polyphenol curcumin has been shown to exert a neuroprotective effect against age-related neurodegenerative diseases such as AD. However, its protective mechanism remains unclear. In this study, we investigated the effects of curcumin on the aggregation of Aβ40 as well as Aβ40 aggregate induced neurotoxicity. Our results show that the curcumin does not inhibit Aβ fibril formation, but rather enriches the population of "off-pathway" soluble oligomers and prefibrillar aggregates that were nontoxic. Curcumin also exerted a nonspecific neuroprotective effect, reducing toxicities induced by a range of Aβ conformers, including monomeric, oligomeric, prefibrillar, and fibrillar Aβ. The neuroprotective effect is possibly membrane-mediated, as curcumin reduced the extent of cell membrane permeabilization induced by Aβ aggregates. Taken together, our study shows that curcumin exerts its neuroprotective effect against Aβ induced toxicity through at least two concerted pathways, modifying the Aβ aggregation pathway toward the formation of nontoxic aggregates and ameliorating Aβ-induced toxicity possibly through a nonspecific pathway.

The state equation of aggregation behaviours for Poly(oxyethylene)-Poly(oxypropylene)-Poly(oxyethylene) tri-block copolymers in aqueous solution

Science.gov (United States)

Gao, Xuechao; Ji, Guozhao; Peng, Tiefeng

2018-03-01

In this work, the aggregation equation is developed to describe the aggregation number of copolymer molecules and micellar diameters from experimental data. Based on the regression parameters in the aggregation equation, it is concluded that the PO parts are beneficial to enlarge the micellar size and the EO parts suppress the formation of the micelles. By fitting the parameters with the EO and PO number, the aggregation equation was proposed to predict the aggregation behaviours of tri-block copolymers having EO units between 26 and 212, and with PO number between 30 and 70. By applying the equation to aqueous solution with salt additives, it can be extended to evaluate the impacts of the additives on the micelle formation.

Engineered aggregation inhibitor fusion for production of highly amyloidogenic human islet amyloid polypeptide.

Science.gov (United States)

Mirecka, Ewa Agnieszka; Gremer, Lothar; Schiefer, Stephanie; Oesterhelt, Filipp; Stoldt, Matthias; Willbold, Dieter; Hoyer, Wolfgang

2014-12-10

Human islet amyloid polypeptide (IAPP) is the major component of pancreatic amyloid deposits in type 2 diabetes. The structural conversion of IAPP from a monomeric state into amyloid assemblies is the subject of intense research. Recombinant production of IAPP is, however, difficult due to its extreme aggregation propensity. Here we describe a novel strategy for expression of IAPP in Escherichia coli, based on an engineered protein tag, which sequesters IAPP monomers and prevents IAPP aggregation. The IAPP-binding protein HI18 was selected by phage display from a β-wrapin library. Fusion of HI18 to IAPP enabled the soluble expression of the construct. IAPP was cleaved from the fusion construct and purified to homogeneity with a yield of 3mg of isotopically labeled peptide per liter of culture. In the monomeric state, IAPP was largely disordered as evidenced by far-UV CD and liquid-state NMR spectroscopy but competent to form amyloid fibrils according to atomic force microscopy. These results demonstrate the ability of the engineered β-wrapin HI18 for shielding the hydrophobic sequence of IAPP during expression and purification. Fusion of aggregation-inhibiting β-wrapins is a suitable approach for the recombinant production of aggregation-prone proteins. Copyright © 2014 Elsevier B.V. All rights reserved.

Towards General Temporal Aggregation

DEFF Research Database (Denmark)

Boehlen, Michael H.; Gamper, Johann; Jensen, Christian Søndergaard

2008-01-01

associated with the management of temporal data. Indeed, temporal aggregation is complex and among the most difficult, and thus interesting, temporal functionality to support. This paper presents a general framework for temporal aggregation that accommodates existing kinds of aggregation, and it identifies...

Sorbitol crystallization-induced aggregation in frozen mAb formulations.

Science.gov (United States)

Piedmonte, Deirdre Murphy; Hair, Alison; Baker, Priti; Brych, Lejla; Nagapudi, Karthik; Lin, Hong; Cao, Wenjin; Hershenson, Susan; Ratnaswamy, Gayathri

2015-02-01

Sorbitol crystallization-induced aggregation of mAbs in the frozen state was evaluated. The effect of protein aggregation resulting from sorbitol crystallization was measured as a function of formulation variables such as protein concentration and pH. Long-term studies were performed on both IgG1 and IgG2 mAbs over the protein concentration range of 0.1-120 mg/mL. Protein aggregation was measured by size-exclusion HPLC (SE-HPLC) and further characterized by capillary-electrophoresis SDS. Sorbitol crystallization was monitored and characterized by subambient differential scanning calorimetry and X-ray diffraction. Aggregation due to sorbitol crystallization is inversely proportional to both protein concentration and formulation pH. At high protein concentrations, sorbitol crystallization was suppressed, and minimal aggregation by SE-HPLC resulted, presumably because of self-stabilization of the mAbs. The glass transition temperature (Tg ') and fragility index measurements were made to assess the influence of molecular mobility on the crystallization of sorbitol. Tg ' increased with increasing protein concentration for both mAbs. The fragility index decreased with increasing protein concentration, suggesting that it is increasingly difficult for sorbitol to crystallize at high protein concentrations. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Mechanical Properties of High Strength Concrete Containing Coal Bottom Ash and Oil-Palm Boiler Clinker as Fine Aggregates

Directory of Open Access Journals (Sweden)

Soofinajafi Mahmood

2016-01-01

Full Text Available This research aims to utilize Coal Furnace Bottom ash (CBA and Oil-Palm Boiler Clinker (OPBC as fine aggregate in concrete mix proportions. They are solid wastes from power plant and Oil Palm industry, respectively. Since these by-products do not have any primary use and are pure waste, an opportunity to use them as aggregate in concrete industry not only is economical but also will be an environmental friendly opportunity leading towards a more sustainable production chain. CBA and OPBC sands had similar grading to normal sand but have lower density and higher water absorption. In a high strength concrete, normal sand was replaced up to 25% with either CBA or OPBC. Test results showed that although water absorption of these wastes was more than normal sand but the slump value of concrete containing each of these wastes showed that these concretes had good workability. All mixes containing these wastes had slightly lower compressive strength at early ages and equivalent or higher compressive strength at later ages compared to control mix. The 28-day compressive strength of these concretes was in the range of 69–76 MPa which can be categorized as high strength concrete. In general, the performance of OPBC was better than CBA at 25% replacement level. However, it is recommended that at least 12.5% of total volume of fine aggregate in a high strength concrete is used of CBA or OPBC.

Reschedule of Distributed Energy Resources by an Aggregator for Market Participation

Directory of Open Access Journals (Sweden)

Pedro Faria

2018-03-01

Full Text Available Demand response aggregators have been developed and implemented all through the world with more seen in Europe and the United States. The participation of aggregators in energy markets improves the access of small-size resources to these, which enables successful business cases for demand-side flexibility. The present paper proposes aggregator’s assessment of the integration of distributed energy resources in energy markets, which provides an optimized reschedule. An aggregation and remuneration model is proposed by using the k-means and group tariff, respectively. The main objective is to identify the available options for the aggregator to define tariff groups for the implementation of demand response. After the first schedule, the distributed energy resources are aggregated into a given number of groups. For each of the new groups, a new tariff is computed and the resources are again scheduled according to the new group tariff. In this way, the impact of implementing the new tariffs is analyzed in order to support a more sustained decision to be taken by the aggregator. A 180-bus network in the case study accommodates 90 consumers, 116 distributed generators, and one supplier.

Commercial and Multifamily Building Tenant Energy Usage Aggregation and Privacy

Energy Technology Data Exchange (ETDEWEB)

Livingston, Olga V.; Pulsipher, Trenton C.; Wang, Na

2014-11-17

In a number of cities and states, building owners are required to disclose and/or benchmark their building energy use. This requires the building owner to possess monthly whole-building energy usage information, which can be challenging for buildings in which individual tenants have their own utility meters and accounts with the utility. Some utilities and utility regulators have turned to aggregation of customer data as a way to give building owners the whole-building energy usage data while protecting customer privacy. However, no utilities or regulators appear to have conducted a concerted statistical, cybersecurity, and privacy analysis to justify the level of aggregation selected. Therefore, the Tennant Data Aggregation Task was established to help utilities address these issues and provide recommendations as well as a theoretical justification of the aggregation threshold. This study is focused on the use case of submitting data for ENERGY STAR Portfolio Manager (ESPM), but it also looks at other potential use cases for monthly energy consumption data.

Africanization in the United States: replacement of feral European honeybees (Apis mellifera L.) by an African hybrid swarm.

Science.gov (United States)

Pinto, M Alice; Rubink, William L; Patton, John C; Coulson, Robert N; Johnston, J Spencer

2005-08-01

The expansion of Africanized honeybees from South America to the southwestern United States in feral population from the southern United States undergoing Africanization. Our microsatellite data showed that (1) the process of Africanization involved both maternal and paternal bidirectional gene flow between European and Africanized honeybees and (2) the panmitic European population was replaced by panmitic mixtures of A. m. scutellata and European genes within 5 years after Africanization. The post-Africanization gene pool (1998-2001) was composed of a diverse array of recombinant classes with a substantial European genetic contribution (mean 25-37%). Therefore, the resulting feral honeybee population of south Texas was best viewed as a hybrid swarm.

Exploiting BSA to Inhibit the Fibrous Aggregation of Magnetic Nanoparticles under an Alternating Magnetic Field

Directory of Open Access Journals (Sweden)

Ning Gu

2013-03-01

Full Text Available The alternating magnetic field was discovered to be capable of inducing the fibrous aggregation of magnetic nanoparticles. However, this anisotropic aggregation may be unfavorable for practical applications. Here, we reported that the adsorption of BSA (bovine serum albumin on the surfaces of magnetic nanoparticles can effectively make the fibrous aggregation of γ-Fe2O3 nanoparticles turn into a more isotropic aggregation in the presence of the alternating magnetic field. Also, the heating curves with and without BSA adsorption under different pH conditions were measured to show the influence of the colloidal aggregation states on the collective calorific behavior of magnetic nanoparticles.

General three-state model with biased population replacement: Analytical solution and application to language dynamics

Science.gov (United States)

Colaiori, Francesca; Castellano, Claudio; Cuskley, Christine F.; Loreto, Vittorio; Pugliese, Martina; Tria, Francesca

2015-01-01

Empirical evidence shows that the rate of irregular usage of English verbs exhibits discontinuity as a function of their frequency: the most frequent verbs tend to be totally irregular. We aim to qualitatively understand the origin of this feature by studying simple agent-based models of language dynamics, where each agent adopts an inflectional state for a verb and may change it upon interaction with other agents. At the same time, agents are replaced at some rate by new agents adopting the regular form. In models with only two inflectional states (regular and irregular), we observe that either all verbs regularize irrespective of their frequency, or a continuous transition occurs between a low-frequency state, where the lemma becomes fully regular, and a high-frequency one, where both forms coexist. Introducing a third (mixed) state, wherein agents may use either form, we find that a third, qualitatively different behavior may emerge, namely, a discontinuous transition in frequency. We introduce and solve analytically a very general class of three-state models that allows us to fully understand these behaviors in a unified framework. Realistic sets of interaction rules, including the well-known naming game (NG) model, result in a discontinuous transition, in agreement with recent empirical findings. We also point out that the distinction between speaker and hearer in the interaction has no effect on the collective behavior. The results for the general three-state model, although discussed in terms of language dynamics, are widely applicable.

Hydrodynamic effects on β-amyloid (16-22) peptide aggregation

Energy Technology Data Exchange (ETDEWEB)

Chiricotto, Mara; Sterpone, Fabio, E-mail: fabio.sterpone@ibpc.fr [Laboratoire de Biochimie Théorique, IBPC, CNRS UPR9080, University Paris Diderot, Sorbonne Paris Cité, 13 rue Pierre et Marie Curie, 75005 Paris (France); Melchionna, Simone [CNR-ISC, Institute for Complex System, Consiglio Nazionale delle Ricerche, Rome (Italy); Derreumaux, Philippe [Laboratoire de Biochimie Théorique, IBPC, CNRS UPR9080, University Paris Diderot, Sorbonne Paris Cité, 13 rue Pierre et Marie Curie, 75005 Paris (France); IUF, Institut Universitaire de France, Boulevard Saint Michel, 75005 Paris (France)

2016-07-21

Computer simulations based on simplified representations are routinely used to explore the early steps of amyloid aggregation. However, when protein models with implicit solvent are employed, these simulations miss the effect of solvent induced correlations on the aggregation kinetics and lifetimes of metastable states. In this work, we apply the multi-scale Lattice Boltzmann Molecular Dynamics technique (LBMD) to investigate the initial aggregation phases of the amyloid Aβ{sub 16−22} peptide. LBMD includes naturally hydrodynamic interactions (HIs) via a kinetic on-lattice representation of the fluid kinetics. The peptides are represented by the flexible OPEP coarse-grained force field. First, we have tuned the essential parameters that control the coupling between the molecular and fluid evolutions in order to reproduce the experimental diffusivity of elementary species. The method is then deployed to investigate the effect of HIs on the aggregation of 100 and 1000 Aβ{sub 16−22} peptides. We show that HIs clearly impact the aggregation process and the fluctuations of the oligomer sizes by favouring the fusion and exchange dynamics of oligomers between aggregates. HIs also guide the growth of the leading largest cluster. For the 100 Aβ{sub 16−22} peptide system, the simulation of ∼300 ns allowed us to observe the transition from ellipsoidal assemblies to an elongated and slightly twisted aggregate involving almost the totality of the peptides. For the 1000 Aβ{sub 16−22} peptides, a system of unprecedented size at quasi-atomistic resolution, we were able to explore a branched disordered fibril-like structure that has never been described by other computer simulations, but has been observed experimentally.

Native myosin from adult rabbit skeletal muscle: isoenzymes and states of aggregation.

Science.gov (United States)

Morel, J E; D'hahan, N; Taouil, K; Francin, M; Aguilar, A; Dalbiez, J P; Merah, Z; Grussaute, H; Hilbert, B; Ollagnon, F; Selva, G; Piot, F

1998-04-21

The globular heads of skeletal muscle myosin have been shown to exist as isoenzymes S1 (A1) and S1 (A2), and there are also isoforms of the heavy chains. Using capillary electrophoresis, we found two dominant isoenzymes of the whole native myosin molecule, in agreement with what has previously been found by various techniques for native and nondenatured myosin from adult rabbits. Findings about possible states of aggregation of myosin and its heads are contradictory. By analytical ultracentrifugation, we confirmed the existence of a tail-tail dimer. By laser light scattering, we found a head-head dimer in the presence of MgATP. Capillary electrophoresis coupled with analytical ultracentrifugation and laser light scattering led us to refine these results. We found tail-tail dimers in a conventional buffer. We found tail-tail and head-head dimers in the presence of 0.5 mM MgATP and pure head-head dimers in the presence of 6 mM MgATP. All the dimers were homodimers. Naming the dominant isoenzymes of myosin a and b, we observed tail-tail dimers with isoenzyme a (TaTa) and with isoenzyme b (TbTb) and also head-head dimers with isoenzyme a (HaHa) and with isoenzyme b (HbHb).

Denitrification in Soil Aggregate Analogues-Effect of Aggregate Size and Oxygen Diffusion

Directory of Open Access Journals (Sweden)

Steffen Schlüter

2018-04-01

Full Text Available Soil-borne nitrous oxide (N2O emissions have a high spatial and temporal variability which is commonly attributed to the occurrence of hotspots and hot moments for microbial activity in aggregated soil. Yet there is only limited information about the biophysical processes that regulate the production and consumption of N2O on microscopic scales in undisturbed soil. In this study, we introduce an experimental framework relying on simplified porous media that circumvents some of the complexities occuring in natural soils while fully accounting for physical constraints believed to control microbial activity in general and denitrification in particular. We used this framework to explore the impact of aggregate size and external oxygen concentration on the kinetics of O2 consumption, as well as CO2 and N2O production. Model aggregates of different sizes (3.5 vs. 7 mm diameter composed of porous, sintered glass were saturated with a defined growth medium containing roughly 109 cells ml−1 of the facultative anaerobic, nosZ-deficient denitrifier Agrobacterium tumefaciens with N2O as final denitrification product and incubated at five different oxygen levels (0–13 vol-%. We demonstrate that the onset of denitrification depends on the amount of external oxygen and the size of aggregates. Smaller aggregates were better supplied with oxygen due to a larger surface-to-volume ratio, which resulted in faster growth and an earlier onset of denitrification. In larger aggregates, the onset of denitrification was more gradual, but with comparably higher N2O production rates once the anoxic aggregate centers were fully developed. The normalized electron flow from the reduced carbon substrate to N-oxyanions (edenit-/etotal- ratio could be solely described as a function of initial oxygen concentration in the headspace with a simple, hyperbolic model, for which the two empirical parameters changed with aggregate size in a consistent way. These findings confirm the

Effect of the Aggregate Size on Strength Properties of Recycled Aggregate Concrete

Directory of Open Access Journals (Sweden)

Ma Kang

2018-01-01

Full Text Available The study on preparation technology of recycled concrete with economical and technical feasibility has gained more serious attention in each country due to its involvement and effect on the environment protection and the sustainable development of human society. In this study, we conducted a control variable test to investigate and assess the influence of the aggregate size on the strength characteristics of concrete with different diameters of recycled aggregates. Concrete with recycled aggregates of 5∼15 mm (A, 15∼20 mm (B, 20∼30 mm (C, and their combinations were subjected to a series of unconfined pressure tests after curing for 28 days. Based on the results obtained from the tests, an effort was made to study the relationship between the mechanical characteristics of recycled aggregate concrete and aggregate particle size. Also, a regression model of recycled concrete was proposed to predict the elasticity modulus and to adjust the design of mixture proportion. It is believed that these experiment results would contribute to adjust the remediation mixture for recycling plants by considering the influence of recycled aggregate size.

Oil-Price Shocks: Beyond Standard Aggregate Demand/Aggregate Supply Analysis.

Science.gov (United States)

Elwood, S. Kirk

2001-01-01

Explores the problems of portraying oil-price shocks using the aggregate demand/aggregate supply model. Presents a simple modification of the model that differentiates between production and absorption of goods, which enables it to better reflect the effects of oil-price shocks on open economies. (RLH)

Cylindrical aggregates of chlorophylls studied by small-angle neutron scatter

Energy Technology Data Exchange (ETDEWEB)

Worcester, D.L. [Univ. of Missouri, Columbus, MO (United States); Katz, J.J. [Argonne National Laboratory, IL (United States)

1994-12-31

Neutron small-angle scattering has demonstrated tubular chlorophyll aggregates formed by self-assembly of a variety of chlorophyll types in nonpolar solvents. The size and other properties of the tubular aggregates can be accounted for by stereochemical properties of the chlorophyll molecules. Features of some of the structures are remarkably similar to light harvesting chlorophyll complexes in vivo, particularly for photosynthetic bacteria. These nanotube chlorophyll structures may have applications as light harvesting biomaterials where efficient energy transfer occurs from an excited state which is highly delocalized.

Studies on use of Copper Slag as Replacement Material for River Sand in Building Constructions

Science.gov (United States)

Madheswaran, C. K.; Ambily, P. S.; Dattatreya, J. K.; Rajamane, N. P.

2014-09-01

This work focuses on the use of copper slag, as a partial replacement of sand for use in cement concrete and building construction. Cement mortar mixtures prepared with fine aggregate made up of different proportions of copper slag and sand were tested for use as masonry mortars and plastering. Three masonry wall panels of dimensions 1 × 1 m were plastered. The studies showed that although copper slag based mortar is suitable for plastering, with the increase in copper slag content, the wastage due to material rebounding from the plastered surfaces increases. It is therefore suggested that the copper slag can be used for plastering of floorings and horizontal up to 50 % by mass of the fine aggregate, and for vertical surfaces, such as, brick/block walls it can be used up to 25 %. In this study on concrete mixtures were prepared with two water cement ratios and different proportions of copper slag ranging from 0 % (for the control mix) to 100 % of fine aggregate. The Concrete mixes were evaluated for workability, density, and compressive strength.

Photo-induced reorganization of molecular packing of amphi-PIC J-aggregates (single J-aggregate spectroscopy)

International Nuclear Information System (INIS)

Malyukin, Yu.V.; Sorokin, A.V.; Yefimova, S.L.; Lebedenko, A.N.

2005-01-01

Confocal luminescence microscopy has been used to excite and collect luminescence from single amphi-PIC J-aggregate. Two types of J-aggregates have been revealed in the luminescence image: bead-like J-aggregates, which diameter is less than 1 μm and rod-like ones, which length is about 3 μm and diameter is less than 1 μm. It has been found that single rod-like and bead-like J-aggregates exhibit different luminescence bands with different decay parameters. At the off-resonance blue tail excitation, the J-aggregate exciton luminescence disappeared within a certain time period and a new band appeared, which cannot be attributed to the monomer emission. The luminescence image shows that the J-aggregate is not destroyed. However, J-aggregate storage in darkness does not recover its exciton luminescence

Studies on recycled aggregates-based concrete.

Science.gov (United States)

Rakshvir, Major; Barai, Sudhirkumar V

2006-06-01

Reduced extraction of raw materials, reduced transportation cost, improved profits, reduced environmental impact and fast-depleting reserves of conventional natural aggregates has necessitated the use of recycling, in order to be able to conserve conventional natural aggregate. In this study various physical and mechanical properties of recycled concrete aggregates were examined. Recycled concrete aggregates are different from natural aggregates and concrete made from them has specific properties. The percentages of recycled concrete aggregates were varied and it was observed that properties such as compressive strength showed a decrease of up to 10% as the percentage of recycled concrete aggregates increased. Water absorption of recycled aggregates was found to be greater than natural aggregates, and this needs to be compensated during mix design.

Energy transfer dynamics in trimers and aggregates of light-harvesting complex II probed by 2D electronic spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Enriquez, Miriam M.; Zhang, Cheng; Tan, Howe-Siang, E-mail: howesiang@ntu.edu.sg [Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Akhtar, Parveen; Garab, Győző; Lambrev, Petar H., E-mail: lambrev@brc.hu [Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged (Hungary)

2015-06-07

The pathways and dynamics of excitation energy transfer between the chlorophyll (Chl) domains in solubilized trimeric and aggregated light-harvesting complex II (LHCII) are examined using two-dimensional electronic spectroscopy (2DES). The LHCII trimers and aggregates exhibit the unquenched and quenched excitonic states of Chl a, respectively. 2DES allows direct correlation of excitation and emission energies of coupled states over population time delays, hence enabling mapping of the energy flow between Chls. By the excitation of the entire Chl b Q{sub y} band, energy transfer from Chl b to Chl a states is monitored in the LHCII trimers and aggregates. Global analysis of the two-dimensional (2D) spectra reveals that energy transfer from Chl b to Chl a occurs on fast and slow time scales of 240–270 fs and 2.8 ps for both forms of LHCII. 2D decay-associated spectra resulting from the global analysis identify the correlation between Chl states involved in the energy transfer and decay at a given lifetime. The contribution of singlet–singlet annihilation on the kinetics of Chl energy transfer and decay is also modelled and discussed. The results show a marked change in the energy transfer kinetics in the time range of a few picoseconds. Owing to slow energy equilibration processes, long-lived intermediate Chl a states are present in solubilized trimers, while in aggregates, the population decay of these excited states is significantly accelerated, suggesting that, overall, the energy transfer within the LHCII complexes is faster in the aggregated state.

Identification of aggregates for Tennessee bituminous surface courses

Science.gov (United States)

Sauter, Heather Jean

Tennessee road construction is a major venue for federal and state spending. Tax dollars each year go to the maintenance and construction of roads. One aspect of highway construction that affects the public is the safety of its state roads. There are many factors that affect the safety of a given road. One factor that was focused on in this research was the polish resistance capabilities of aggregates. Several pre-evaluation methods have been used in the laboratory to predict what will happen in a field situation. A new pre-evaluation method was invented that utilized AASHTO T 304 procedure upscaled to accommodate surface bituminous aggregates. This new method, called the Tennessee Terminal Textural Condition Method (T3CM), was approved by Tennessee Department of Transportation to be used as a pre-evaluation method on bituminous surface courses. It was proven to be operator insensitive, repeatable, and an accurate indication of particle shape and texture. Further research was needed to correlate pre-evaluation methods to the current field method, ASTM E 274-85 Locked Wheel Skid Trailer. In this research, twenty-five in-place bituminous projects and eight source evaluations were investigated. The information gathered would further validate the T3CM and find the pre-evaluation method that best predicted the field method. In addition, new sources of aggregates for bituminous surface courses were revealed. The results of this research have shown T3CM to be highly repeatable with an overall coefficient of variation of 0.26% for an eight sample repeatability test. It was the best correlated pre-evaluation method with the locked wheel skid trailer method giving an R2 value of 0.3946 and a Pearson coefficient of 0.710. Being able to predict field performance of aggregates prior to construction is a powerful tool capable of saving time, money, labor, and possibly lives.

Social aggregation in pea aphids: experiment and random walk modeling.

Directory of Open Access Journals (Sweden)

Christa Nilsen

Full Text Available From bird flocks to fish schools and ungulate herds to insect swarms, social biological aggregations are found across the natural world. An ongoing challenge in the mathematical modeling of aggregations is to strengthen the connection between models and biological data by quantifying the rules that individuals follow. We model aggregation of the pea aphid, Acyrthosiphon pisum. Specifically, we conduct experiments to track the motion of aphids walking in a featureless circular arena in order to deduce individual-level rules. We observe that each aphid transitions stochastically between a moving and a stationary state. Moving aphids follow a correlated random walk. The probabilities of motion state transitions, as well as the random walk parameters, depend strongly on distance to an aphid's nearest neighbor. For large nearest neighbor distances, when an aphid is essentially isolated, its motion is ballistic with aphids moving faster, turning less, and being less likely to stop. In contrast, for short nearest neighbor distances, aphids move more slowly, turn more, and are more likely to become stationary; this behavior constitutes an aggregation mechanism. From the experimental data, we estimate the state transition probabilities and correlated random walk parameters as a function of nearest neighbor distance. With the individual-level model established, we assess whether it reproduces the macroscopic patterns of movement at the group level. To do so, we consider three distributions, namely distance to nearest neighbor, angle to nearest neighbor, and percentage of population moving at any given time. For each of these three distributions, we compare our experimental data to the output of numerical simulations of our nearest neighbor model, and of a control model in which aphids do not interact socially. Our stochastic, social nearest neighbor model reproduces salient features of the experimental data that are not captured by the control.

Deformation Behavior of Recycled Concrete Aggregate during Cyclic and Dynamic Loading Laboratory Tests

Directory of Open Access Journals (Sweden)

Wojciech Sas

2016-09-01

Full Text Available Recycled concrete aggregate (RCA is a relatively new construction material, whose applications can replace natural aggregates. To do so, extensive studies on its mechanical behavior and deformation characteristics are still necessary. RCA is currently used as a subbase material in the construction of roads, which are subject to high settlements due to traffic loading. The deformation characteristics of RCA must, therefore, be established to find the possible fatigue and damage behavior for this new material. In this article, a series of triaxial cyclic loading and resonant column tests is used to characterize fatigue in RCA as a function of applied deviator stress after long-term cyclic loading. A description of the shakedown phenomenon occurring in the RCA and calculations of its resilient modulus (Mr as a function of fatigue are also presented. Test result analysis with the stress-life method on the Wohler S-N diagram shows the RCA behavior in accordance with the Basquin law.

Effects of sucrose on rFVIIa aggregation and methionine oxidation

DEFF Research Database (Denmark)

Soenderkaer, Susanne; Carpenter, John F; van de Weert, Marco

2004-01-01

The aim of this study was to characterize the effects of sucrose on the stability of recombinant factor VIIa (rFVIIa), with special emphasis on aggregation and methionine oxidation, as well as to investigate the impact of various environmental conditions on the rFVIIa conformation. The stability...... of rFVIIa was studied at pH 5. Aggregation was monitored using size exclusion high-performance liquid chromatography (SE-HPLC), whereas formation of methionine oxidation products was measured by reversed-phase high-performance liquid chromatography (RP-HPLC). Fourier transform infrared (FTIR...... the protein's surface, which shifts the protein molecular population away from expanded aggregation competent species and toward the compact native state, is thought to account for these observations. rFVIIa is sensitive to methionine oxidation; two mono-oxidized and one di-oxidized product were formed upon...

An exact approach for aggregated formulations

DEFF Research Database (Denmark)

Gamst, Mette; Spoorendonk, Simon; Røpke, Stefan

Aggregating formulations is a powerful approach for problems to take on tractable forms. Aggregation may lead to loss of information, i.e. the aggregated formulation may be an approximation of the original problem. In branch-and-bound context, aggregation can also complicate branching, e.g. when...... optimality cannot be guaranteed by branching on aggregated variables. We present a generic exact solution method to remedy the drawbacks of aggregation. It combines the original and aggregated formulations and applies Benders' decomposition. We apply the method to the Split Delivery Vehicle Routing Problem....

Protein aggregate turbidity: Simulation of turbidity profiles for mixed-aggregation reactions.

Science.gov (United States)

Hall, Damien; Zhao, Ran; Dehlsen, Ian; Bloomfield, Nathaniel; Williams, Steven R; Arisaka, Fumio; Goto, Yuji; Carver, John A

2016-04-01

Due to their colloidal nature, all protein aggregates scatter light in the visible wavelength region when formed in aqueous solution. This phenomenon makes solution turbidity, a quantity proportional to the relative loss in forward intensity of scattered light, a convenient method for monitoring protein aggregation in biochemical assays. Although turbidity is often taken to be a linear descriptor of the progress of aggregation reactions, this assumption is usually made without performing the necessary checks to provide it with a firm underlying basis. In this article, we outline utilitarian methods for simulating the turbidity generated by homogeneous and mixed-protein aggregation reactions containing fibrous, amorphous, and crystalline structures. The approach is based on a combination of Rayleigh-Gans-Debye theory and approximate forms of the Mie scattering equations. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

Aggregates from mineral wastes

Directory of Open Access Journals (Sweden)

Baic Ireneusz

2016-01-01

Full Text Available The problem concerning the growing demand for natural aggregates and the need to limit costs, including transportation from remote deposits, cause the increase in growth of interest in aggregates from mineral wastes as well as in technologies of their production and recovery. The paper presents the issue related to the group of aggregates other than natural. A common name is proposed for such material: “alternative aggregates”. The name seems to be fully justified due to adequacy of this term because of this raw materials origin and role, in comparison to the meaning of natural aggregates based on gravel and sand as well as crushed stones. The paper presents characteristics of the market and basic application of aggregates produced from mineral wastes, generated in the mining, power and metallurgical industries as well as material from demolished objects.

Agregação e estabilidade de agregados do solo em sistemas agropecuários em Mato Grosso do Sul Soil aggregation and aggregate stability under crop-pasture systems in Mato Grosso do Sul state, Brazil

Directory of Open Access Journals (Sweden)

Júlio Cesar Salton

2008-02-01

Full Text Available Sistemas de manejo do solo, incluindo lavouras em plantio direto, lavouras (soja em rotação com pastagens em plantio direto e pastagens permanentes (Brachiaria sp., foram avaliados quanto à agregação do solo e estabilidade dos agregados. Em três experimentos de longa duração (9 e 11 anos localizados em Mato Grosso do Sul, o solo foi amostrado nas camadas de 0 a 5, 5 a 10 e 10 a 20 cm, para determinação da estabilidade dos agregados em água e a seco. Foram calculados o diâmetro médio ponderado (DMP e o índice de estabilidade dos agregados (IEA. Em todos os experimentos, nos sistemas com pastagens, seja de forma isolada ou em rotação com lavouras, foi verificado maior volume do solo, constituindo agregados com tamanho superior a 4,76 mm. Os sistemas com pastagens também apresentaram maior DMP e maior IEA em todos os experimentos. O sistema apenas com lavouras apresentou, nos três experimentos, o maior volume de solo com agregados de tamanho entre 0,25 e 2,00 mm. Esses efeitos ocorreram de forma semelhante em todas as profundidades avaliadas. Entre os locais, observou-se o efeito do teor de argila na agregação, sendo maior em Maracaju e menor em Campo Grande. Foi observada estreita relação entre a estabilidade dos agregados e o teor de C no solo. A formação de macroagregados parece estar relacionada à presença de raízes, que são mais abundantes sob pastagem de gramíneas.Soil management systems, with crops under no-tillage (NT, crops (soybean in rotation with pastures under NT and permanent pastures (Brachiaria sp., were evaluated for soil aggregation and aggregate stability. Three long-term experiments (9 and 11 years in the state of Mato Grosso do Sul were sampled in the layers 0-5, 5-10 and 10-20 cm for determination of the aggregate stability in wet and dry sieving. The mean weight diameter (MWD and the aggregate stability index (IAS were calculated. In all experiments, the greatest soil volume was verified in the

Aggregated Computational Toxicology Online Resource

Data.gov (United States)

U.S. Environmental Protection Agency — Aggregated Computational Toxicology Online Resource (AcTOR) is EPA's online aggregator of all the public sources of chemical toxicity data. ACToR aggregates data...

Real-time amyloid aggregation monitoring with a photonic crystal-based approach.

Science.gov (United States)

Santi, Sara; Musi, Valeria; Descrovi, Emiliano; Paeder, Vincent; Di Francesco, Joab; Hvozdara, Lubos; van der Wal, Peter; Lashuel, Hilal A; Pastore, Annalisa; Neier, Reinhard; Herzig, Hans Peter

2013-10-21

We propose the application of a new label-free optical technique based on photonic nanostructures to real-time monitor the amyloid-beta 1-42 (Aβ(1-42)) fibrillization, including the early stages of the aggregation process, which are related to the onset of the Alzheimer's Disease (AD). The aggregation of Aβ peptides into amyloid fibrils has commonly been associated with neuronal death, which culminates in the clinical features of the incurable degenerative AD. Recent studies revealed that cell toxicity is determined by the formation of soluble oligomeric forms of Aβ peptides in the early stages of aggregation. At this phase, classical amyloid detection techniques lack in sensitivity. Upon a chemical passivation of the sensing surface by means of polyethylene glycol, the proposed approach allows an accurate, real-time monitoring of the refractive index variation of the solution, wherein Aβ(1-42) peptides are aggregating. This measurement is directly related to the aggregation state of the peptide throughout oligomerization and subsequent fibrillization. Our findings open new perspectives in the understanding of the dynamics of amyloid formation, and validate this approach as a new and powerful method to screen aggregation at early stages. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multistate Outbreak of Salmonella Virchow Infections Linked to a Powdered Meal Replacement Product - United States, 2015-2016.

Science.gov (United States)

Gambino-Shirley, Kelly J; Tesfai, Adiam; Schwensohn, Colin A; Burnett, Cindy; Smith, Lori; Wagner, Jennifer M; Eikmeier, Dana; Smith, Kirk; Stone, Jolianne P; Updike, Dawn; Hines, Jonas; Shade, Lauren N; Tolar, Beth; Fu, Tong-Jen; Viazis, Stelios; Seelman, Sharon L; Blackshear, Kathryn; Wise, Matthew E; Neil, Karen P

2018-03-07

Nontyphoidal Salmonella is the leading cause of bacterial gastroenteritis in the United States. Meal replacement products containing raw and 'superfood' ingredients have gained increasing popularity among consumers in recent years. In January 2016, we investigated a multistate outbreak of infections with a novel strain of Salmonella Virchow. Cases were defined using molecular subtyping procedures. Commonly reported exposures were compared with responses from healthy people interviewed in the 2006-2007 FoodNet Population Survey. Firm inspections and product traceback and testing were performed. Thirty-five cases from 24 states were identified; 6 hospitalizations and no deaths were reported. Thirty-one (94%) of 33 ill people interviewed reported consuming a powdered supplement in the week before illness; of these, 30 (97%) reported consuming Product A, a raw organic powdered shake product consumed as a meal replacement. Laboratory testing isolated the outbreak strain of Salmonella Virchow from: leftover Product A collected from ill people's homes, organic moringa leaf powder (an ingredient in Product A), and finished product retained by the firm. Firm inspections at three facilities linked to Product A production did not reveal contamination at the facilities. Traceback identified that the contaminated moringa leaf powder was imported from South Africa. This investigation identified a novel outbreak vehicle and highlighted the potential risk with similar products not intended to be cooked by consumers before consuming. The company issued a voluntary recall of all implicated products. As this product has a long shelf-life, the recall likely prevented additional illnesses.

Aggregation and pH-temperature phase behavior for aggregates of an IgG2 antibody.

Science.gov (United States)

Sahin, Erinc; Weiss, William F; Kroetsch, Andrew M; King, Kevin R; Kessler, R Kendall; Das, Tapan K; Roberts, Christopher J

2012-05-01

Monomer unfolding and thermally accelerated aggregation kinetics to produce soluble oligomers or insoluble macroscopic aggregates were characterized as a function of pH for an IgG2 antibody using differential scanning calorimetry (DSC) and size-exclusion chromatography (SEC). Aggregate size was quantified via laser light scattering, and aggregate solubility via turbidity and visual inspection. Interestingly, nonnative oligomers were soluble at pH 5.5 above approximately 15°C, but converted reversibly to visible/insoluble particles at lower temperatures. Lower pH values yielded only soluble aggregates, whereas higher pH resulted in insoluble aggregates, regardless of the solution temperature. Unlike the growing body of literature that supports the three-endotherm model of IgG1 unfolding in DSC, the results here also illustrate limitations of that model for other monoclonal antibodies. Comparison of DSC with monomer loss (via SEC) from samples during thermal scanning indicates that the least conformationally stable domain is not the most aggregation prone, and that a number of the domains remain intact within the constituent monomers of the resulting aggregates. This highlights continued challenges with predicting a priori which domain(s) or thermal transition(s) is(are) most relevant for product stability with respect to aggregation. Copyright © 2012 Wiley Periodicals, Inc.

Ultrasensitive detection of target analyte-induced aggregation of gold nanoparticles using laser-induced nanoparticle Rayleigh scattering.

Science.gov (United States)

Lin, Jia-Hui; Tseng, Wei-Lung

2015-01-01

Detection of salt- and analyte-induced aggregation of gold nanoparticles (AuNPs) mostly relies on costly and bulky analytical instruments. To response this drawback, a portable, miniaturized, sensitive, and cost-effective detection technique is urgently required for rapid field detection and monitoring of target analyte via the use of AuNP-based sensor. This study combined a miniaturized spectrometer with a 532-nm laser to develop a laser-induced Rayleigh scattering technique, allowing the sensitive and selective detection of Rayleigh scattering from the aggregated AuNPs. Three AuNP-based sensing systems, including salt-, thiol- and metal ion-induced aggregation of the AuNPs, were performed to examine the sensitivity of laser-induced Rayleigh scattering technique. Salt-, thiol-, and metal ion-promoted NP aggregation were exemplified by the use of aptamer-adsorbed, fluorosurfactant-stabilized, and gallic acid-capped AuNPs for probing K(+), S-adenosylhomocysteine hydrolase-induced hydrolysis of S-adenosylhomocysteine, and Pb(2+), in sequence. Compared to the reported methods for monitoring the aggregated AuNPs, the proposed system provided distinct advantages of sensitivity. Laser-induced Rayleigh scattering technique was improved to be convenient, cheap, and portable by replacing a diode laser and a miniaturized spectrometer with a laser pointer and a smart-phone. Using this smart-phone-based detection platform, we can determine whether or not the Pb(2+) concentration exceed the maximum allowable level of Pb(2+) in drinking water. Copyright © 2014 Elsevier B.V. All rights reserved.

In silico engineering of aggregation-prone recombinant proteins for substrate recognition by the chaperonin GroEL.

Science.gov (United States)

Kumar, Vipul; Punetha, Ankita; Sundar, Durai; Chaudhuri, Tapan K

2012-01-01

Molecular chaperones appear to have been evolved to facilitate protein folding in the cell through entrapment of folding intermediates on the interior of a large cavity formed between GroEL and its co-chaperonin GroES. They bind newly synthesized or non-native polypeptides through hydrophobic interactions and prevent their aggregation. Some proteins do not interact with GroEL, hence even though they are aggregation prone, cannot be assisted by GroEL for their folding. In this study, we have attempted to engineer these non-substrate proteins to convert them as the substrate for GroEL, without compromising on their function. We have used a computational biology approach to generate mutants of the selected proteins by selectively mutating residues in the hydrophobic patch, similar to GroES mobile loop region that are responsible for interaction with GroEL, and compared with the wild counterparts for calculation of their instability and aggregation propensities. The energies of the newly designed mutants were computed through molecular dynamics simulations. We observed increased aggregation propensity of some of the mutants formed after replacing charged amino acid residues with hydrophobic ones in the well defined hydrophobic patch, raising the possibility of their binding ability to GroEL. The newly generated mutants may provide potential substrates for Chaperonin GroEL, which can be experimentally generated and tested for their tendency of aggregation, interactions with GroEL and the possibility of chaperone-assisted folding to produce functional proteins.

A bivariate optimal replacement policy for a multistate repairable system

International Nuclear Information System (INIS)

Zhang Yuanlin; Yam, Richard C.M.; Zuo, Ming J.

2007-01-01

In this paper, a deteriorating simple repairable system with k+1 states, including k failure states and one working state, is studied. It is assumed that the system after repair is not 'as good as new' and the deterioration of the system is stochastic. We consider a bivariate replacement policy, denoted by (T,N), in which the system is replaced when its working age has reached T or the number of failures it has experienced has reached N, whichever occurs first. The objective is to determine the optimal replacement policy (T,N)* such that the long-run expected profit per unit time is maximized. The explicit expression of the long-run expected profit per unit time is derived and the corresponding optimal replacement policy can be determined analytically or numerically. We prove that the optimal policy (T,N)* is better than the optimal policy N* for a multistate simple repairable system. We also show that a general monotone process model for a multistate simple repairable system is equivalent to a geometric process model for a two-state simple repairable system in the sense that they have the same structure for the long-run expected profit (or cost) per unit time and the same optimal policy. Finally, a numerical example is given to illustrate the theoretical results

Sintering study in vertical fixed bed reactor for synthetic aggregate production

International Nuclear Information System (INIS)

Quaresma, D.S.; Neves, A.S.S.; Melo, A.O.; Pereira, L.F.S.; Bezerra, P.T.S.; Macedo, E.N.; Souza, J.A.S.

2017-01-01

The synthetic aggregates are being employed in civil construction for the reduction of mineral extraction activities. Within this context, the recycling of industrial waste is the basis of the majority of processes to reduce the exploitation of mineral resources. In this work the sintering in a vertical fixed bed reactor for synthetic aggregate production using 20% pellets and 80% charcoal was studied. The pellets were prepared from a mixture containing clay, charcoal and fly ash. Two experiments varying the speed of air sucking were carried out. The material produced was analyzed by X-ray diffraction, scanning electron microscopy, measures of their ceramic properties, and particle size analysis. The results showed that the solid-state reactions, during the sintering process, were efficient and the produced material was classified as coarse lightweight aggregate. The process is interesting for the sintering of aggregates, and can be controlled by composition, particle size, temperature gradient and gaseous flow. (author)

The effect of transient conditions on synovial fluid protein aggregation lubrication.

Science.gov (United States)

Myant, Connor William; Cann, Philippa

2014-06-01

Little is known about the prevailing lubrication mechanisms in artificial articular joints and the way in which these mechanisms determine implant performance. The authors propose that interfacial film formation is determined by rheological changes local to the contact and is driven by aggregation of synovial fluid proteins within the contact inlet region. A direct relationship between contact film thickness and size of the protein aggregation within the inlet region has been observed. In this paper the latest experimental observations of the protein aggregation mechanism are presented for conditions which more closely mimic joint kinematics and loading. Lubricant films were measured for a series of bovine calf serum solutions for CoCrMo femoral component sliding against a glass disc. An optical interferometric apparatus was employed to study the effects of transient motion on lubricant film formation. Central film thickness was measured as a function of time for a series of transient entrainment conditions; start-up motion, steady-state and non-steady-state uni-directional sliding, and bi-directional sliding. The size of the inlet aggregations was found to be dependent upon the type of transient condition. Thick protective protein films were observed to build up within the main contact region for all uni-directional tests. In contrast the inlet aggregation was not observed for bi-directional tests. Contact film thickness and wear was found to be directly proportional to the presence of the inlet protein phase. The inlet phase and contact films were found to be fragile when disrupted by surface scratches or subjected to reversal of the sliding direction. Copyright © 2014 Elsevier Ltd. All rights reserved.

Maillard-reaction-induced modification and aggregation of proteins and hardening of texture in protein bar model systems.

Science.gov (United States)

Zhou, Peng; Guo, Mufan; Liu, Dasong; Liu, Xiaoming; Labuza, Teodore P

2013-03-01

The hardening of high-protein bars causes problems in their acceptability to consumers. The objective of this study was to determine the progress of the Maillard reaction in model systems of high-protein nutritional bars containing reducing sugars, and to illustrate the influences of the Maillard reaction on the modification and aggregation of proteins and the hardening of bar matrices during storage. The progress of the Maillard reaction, glycation, and aggregation of proteins, and textural changes in bar matrices were investigated during storage at 25, 35, and 45 °C. The initial development of the Maillard reaction caused little changes in hardness; however, further storage resulted in dramatic modification of protein with formation of high-molecular-weight polymers, resulting in the hardening in texture. The replacement of reducing sugars with nonreducing ingredients such as sugar alcohols in the formula minimized the changes in texture. The hardening of high-protein bars causes problems in their acceptability to consumers. Maillard reaction is one of the mechanisms contributing to the hardening of bar matrix, particularly for the late stage of storage. The replacement of reducing sugars with nonreducing ingredients such as sugar alcohols in the formula will minimize the changes in texture. © 2013 Institute of Food Technologists®

Sustainable High Quality Recycling of Aggregates from Waste-to-Energy, Treated in a Wet Bottom Ash Processing Installation, for Use in Concrete Products.

Science.gov (United States)

Van den Heede, Philip; Ringoot, Niels; Beirnaert, Arno; Van Brecht, Andres; Van den Brande, Erwin; De Schutter, Geert; De Belie, Nele

2015-12-25

Nowadays, more efforts towards sustainability are required from the concrete industry. Replacing traditional aggregates by recycled bottom ash (BA) from municipal solid waste incineration can contribute to this goal. Until now, only partial replacement has been considered to keep the concrete workability, strength and durability under control. In this research, the feasibility of a full aggregate replacement was investigated for producing prefabricated Lego bricks. It was found that the required compressive strength class for this purpose (C20/25) could be achieved. Nevertheless, a thorough understanding of the BA properties is needed to overcome other issues. As BA is highly absorptive, the concrete's water demand is high. This workability issue can be dealt with by subjecting the fine BA fraction to a crushing operation to eliminate the porous elements and by pre-wetting the fine and coarse BA fractions in a controlled manner. In addition, a reactive NaOH washing is needed to avoid formation of longitudinal voids and the resulting expansion due to the metallic aluminum present in the BA. Regarding the long-term behavior, heavy metal leaching and freeze-thaw exposure are not problematic, though there is susceptibility to acetic and lactic acid attack and maybe increased sensitivity to alkali-silica reaction.

Sustainable High Quality Recycling of Aggregates from Waste-to-Energy, Treated in a Wet Bottom Ash Processing Installation, for Use in Concrete Products

Science.gov (United States)

Van den Heede, Philip; Ringoot, Niels; Beirnaert, Arno; Van Brecht, Andres; Van den Brande, Erwin; De Schutter, Geert; De Belie, Nele

2015-01-01

Nowadays, more efforts towards sustainability are required from the concrete industry. Replacing traditional aggregates by recycled bottom ash (BA) from municipal solid waste incineration can contribute to this goal. Until now, only partial replacement has been considered to keep the concrete workability, strength and durability under control. In this research, the feasibility of a full aggregate replacement was investigated for producing prefabricated Lego bricks. It was found that the required compressive strength class for this purpose (C20/25) could be achieved. Nevertheless, a thorough understanding of the BA properties is needed to overcome other issues. As BA is highly absorptive, the concrete’s water demand is high. This workability issue can be dealt with by subjecting the fine BA fraction to a crushing operation to eliminate the porous elements and by pre-wetting the fine and coarse BA fractions in a controlled manner. In addition, a reactive NaOH washing is needed to avoid formation of longitudinal voids and the resulting expansion due to the metallic aluminum present in the BA. Regarding the long-term behavior, heavy metal leaching and freeze-thaw exposure are not problematic, though there is susceptibility to acetic and lactic acid attack and maybe increased sensitivity to alkali-silica reaction. PMID:28787809

Sustainable High Quality Recycling of Aggregates from Waste-to-Energy, Treated in a Wet Bottom Ash Processing Installation, for Use in Concrete Products

Directory of Open Access Journals (Sweden)

Philip Van den Heede

2015-12-01

Full Text Available Nowadays, more efforts towards sustainability are required from the concrete industry. Replacing traditional aggregates by recycled bottom ash (BA from municipal solid waste incineration can contribute to this goal. Until now, only partial replacement has been considered to keep the concrete workability, strength and durability under control. In this research, the feasibility of a full aggregate replacement was investigated for producing prefabricated Lego bricks. It was found that the required compressive strength class for this purpose (C20/25 could be achieved. Nevertheless, a thorough understanding of the BA properties is needed to overcome other issues. As BA is highly absorptive, the concrete’s water demand is high. This workability issue can be dealt with by subjecting the fine BA fraction to a crushing operation to eliminate the porous elements and by pre-wetting the fine and coarse BA fractions in a controlled manner. In addition, a reactive NaOH washing is needed to avoid formation of longitudinal voids and the resulting expansion due to the metallic aluminum present in the BA. Regarding the long-term behavior, heavy metal leaching and freeze-thaw exposure are not problematic, though there is susceptibility to acetic and lactic acid attack and maybe increased sensitivity to alkali-silica reaction.

Effect of fly ash content towards Sulphate resistance of oil palm shell lightweight aggregate concrete

Science.gov (United States)

Muthusamy, K.; Fadzil, M. Y.; Nazrin Akmal, A. Z. Muhammad; Ahmad, S. Wan; Nur Azzimah, Z.; Hanafi, H. Mohd; Mohamad Hafizuddin, R.

2018-04-01

Both oil palm shell (OPS) and fly ash are by-product generated from the industries. Disposal of these by-product as wastes cause negative impact to the environment. The use of both oil palm shell and fly ash in concrete is seen as an economical solution for making green and denser concrete. The primary aim of this research is to determine the effects of FA utilization as sand replacement in oil palm shell lightweight aggregate concrete (OPS LWAC) towards sulphate resistance. Five concrete mixes containing fly ash as sand replacement namely 0%, 10%, 20%, 30% and 40% were prepared in these experimental work. All mixes were cast in form of cubes before subjected to sulphate solution for the period of 5 months. It was found that addition of 10% fly ash as sand replacement content resulted in better sulphate resistance of OPS LWAC. The occurrence of pozzolanic reaction due to the presence of FA in concrete has consumed the vulnerable Calcium hydroxide to be secondary C-S-H gel making the concrete denser and more durable.

Kinetics of aggregation with choice.

Science.gov (United States)

Ben-Naim, E; Krapivsky, P L

2016-12-01

We generalize the ordinary aggregation process to allow for choice. In ordinary aggregation, two random clusters merge and form a larger aggregate. In our implementation of choice, a target cluster and two candidate clusters are randomly selected and the target cluster merges with the larger of the two candidate clusters. We study the long-time asymptotic behavior and find that as in ordinary aggregation, the size density adheres to the standard scaling form. However, aggregation with choice exhibits a number of different features. First, the density of the smallest clusters exhibits anomalous scaling. Second, both the small-size and the large-size tails of the density are overpopulated, at the expense of the density of moderate-size clusters. We also study the complementary case where the smaller candidate cluster participates in the aggregation process and find an abundance of moderate clusters at the expense of small and large clusters. Additionally, we investigate aggregation processes with choice among multiple candidate clusters and a symmetric implementation where the choice is between two pairs of clusters.

Increased Durability of Concrete Made with Fine Recycled Concrete Aggregates Using Superplasticizers.

Science.gov (United States)

Cartuxo, Francisco; de Brito, Jorge; Evangelista, Luis; Jiménez, José Ramón; Ledesma, Enrique F

2016-02-08

This paper evaluates the influence of two superplasticizers (SP) on the durability properties of concrete made with fine recycled concrete aggregate (FRCA). For this purpose, three families of concrete were tested: concrete without SP, concrete made with a regular superplasticizer and concrete made with a high-performance superplasticizer. Five volumetric replacement ratios of natural sand by FRCA were tested: 0%, 10%, 30%, 50% and 100%. Two natural gravels were used as coarse aggregates. All mixes had the same particle size distribution, cement content and amount of superplasticizer. The w/c ratio was calibrated to obtain similar slump. The results showed that the incorporation of FRCA increased the water absorption by immersion, the water absorption by capillary action, the carbonation depth and the chloride migration coefficient, while the use of superplasticizers highly improved these properties. The incorporation of FRCA jeopardized the SP's effectiveness. This research demonstrated that, from a durability point of view, the simultaneous incorporation of FRCA and high-performance SP is a viable sustainable solution for structural concrete production.

Testosterone Replacement, Muscle Strength, and Physical Function

Directory of Open Access Journals (Sweden)

You-Seon Nam

2018-05-01

Full Text Available Muscle strength and physical function decrease in older men, as do testosterone levels. Nonetheless, the effects of testosterone replacement therapy on muscle strength and physical function remain inconclusive and equivocal. We conducted a rapid systematic review, the results of which showed that testosterone replacement does not affect muscle strength (measured by hand grip strength and leg muscle strength, although it may increase physical function (measured by the 6-minute walk test, Physical Activity Scale for the Elderly score, and other physical performance tests. However, most of the studies were conducted in the United States or Europe and did not include participants from Asian or other ethnic backgrounds; therefore, further studies are needed to evaluate the effects of testosterone replacement in a broader population.

Estimating linear temporal trends from aggregated environmental monitoring data

Science.gov (United States)

Erickson, Richard A.; Gray, Brian R.; Eager, Eric A.

2017-01-01

Trend estimates are often used as part of environmental monitoring programs. These trends inform managers (e.g., are desired species increasing or undesired species decreasing?). Data collected from environmental monitoring programs is often aggregated (i.e., averaged), which confounds sampling and process variation. State-space models allow sampling variation and process variations to be separated. We used simulated time-series to compare linear trend estimations from three state-space models, a simple linear regression model, and an auto-regressive model. We also compared the performance of these five models to estimate trends from a long term monitoring program. We specifically estimated trends for two species of fish and four species of aquatic vegetation from the Upper Mississippi River system. We found that the simple linear regression had the best performance of all the given models because it was best able to recover parameters and had consistent numerical convergence. Conversely, the simple linear regression did the worst job estimating populations in a given year. The state-space models did not estimate trends well, but estimated population sizes best when the models converged. We found that a simple linear regression performed better than more complex autoregression and state-space models when used to analyze aggregated environmental monitoring data.

Kinetic Behaviors of Catalysis-Driven Growth of Three-Species Aggregates on Base of Exchange-Driven Aggregations

International Nuclear Information System (INIS)

Sun Yunfei; Chen Dan; Lin Zhenquan; Ke Jianhong

2009-01-01

We propose a solvable aggregation model to mimic the evolution of population A, asset B, and the quantifiable resource C in a society. In this system, the population and asset aggregates themselves grow through self-exchanges with the rate kernels K 1 (k, j) = K 1 kj and K 2 (k, j) = K 2 kj, respectively. The actions of the population and asset aggregations on the aggregation evolution of resource aggregates are described by the population-catalyzed monomer death of resource aggregates and asset-catalyzed monomer birth of resource aggregates with the rate kernels J 1 (k, j) = J 1 k and J 2 (k, j) = J 2 k, respectively. Meanwhile, the asset and resource aggregates conjunctly catalyze the monomer birth of population aggregates with the rate kernel I 1 (k, i, j) = I 1 ki μ j η , and population and resource aggregates conjunctly catalyze the monomer birth of asset aggregates with the rate kernel I 2 (k, i, j) = I 2 ki v j η . The kinetic behaviors of species A, B, and C are investigated by means of the mean-field rate equation approach. The effects of the population-catalyzed death and asset-catalyzed birth on the evolution of resource aggregates based on the self-exchanges of population and asset appear in effective forms. The coefficients of the effective population-catalyzed death and the asset-catalyzed birth are expressed as J 1e = J 1 /K 1 and J 2e = J 2 /K 2 , respectively. The aggregate size distribution of C species is found to be crucially dominated by the competition between the effective death and the effective birth. It satisfies the conventional scaling form, generalized scaling form, and modified scaling form in the cases of J 1e 2e , J 1e = J 2e , and J 1e > J 2e , respectively. Meanwhile, we also find the aggregate size distributions of populations and assets both fall into two distinct categories for different parameters μ, ν, and η: (i) When μ = ν = η = 0 and μ = ν = 0, η = 1, the population and asset aggregates obey the generalized

Intra-chain organisation of hydrophobic residues controls inter-chain aggregation rates of amphiphilic polymers

Science.gov (United States)

Varilly, Patrick; Willard, Adam P.; Kirkegaard, Julius B.; Knowles, Tuomas P. J.; Chandler, David

2017-04-01

Aggregation of amphiphiles through the action of hydrophobic interactions is a common feature in soft condensed matter systems and is of particular importance in the context of biophysics as it underlies both the generation of functional biological machinery as well as the formation of pathological misassembled states of proteins. Here we explore the aggregation behaviour of amphiphilic polymers using lattice Monte Carlo calculations and show that the distribution of hydrophobic residues within the polymer sequence determines the facility with which dry/wet interfaces can be created and that such interfaces drive the aggregation process.

Implementation of aggregation in the North American power industry

International Nuclear Information System (INIS)

Feldman, R.; Williams, G.

1998-01-01

One key to the impact of deregulation being transmitted to residential customers is the successful formation of aggregation groups and their expansion to include different classes of customers with convergent usage interests. This activity currently is being sponsored not only by for-profit brokerage entities, but also by associations of not-for-profit corporations such as hospitals and universities and by countries. The issues presented fall into several categories. (1) Technical rate taking--feasibility of making appropriate arrangements for alternative supply to consumers on a basis which appropriately reflects customer characteristics and also confers benefit on them all; (2) Legal--Compatibility of proposed arrangements with FERC wholesale regulation under Order No. 888 and emerging state regulation under the different restructuring regimes which their state utility commissions are implementing; (3) Marketing/Sociopolitical--Utilization of modern marketing techniques to effect the political consensus which is a precursor of alternative aggregation arrangements; (4) Financing--identification of capital costs; techniques for financing such costs, including monetization of the savings to be realized. The presentation will extrapolate the potential future significance of aggregation as a force in both restructuring and the development of merchant power projects. It will also assess the extent to which institutional, legal, technical or financial factors may modify the ultimate significance of aggression in the North American Power Industry

The molecular aggregation of pyronin Y in natural bentonite clay suspension

International Nuclear Information System (INIS)

Meral, Kadem; Yilmaz, Nuray; Kaya, Mehmet; Tabak, Ahmet; Onganer, Yavuz

2011-01-01

The molecular aggregation and spectroscopic properties of Pyronin Y (PyY) in the suspension containing natural bentonite clay were studied using molecular absorption, steady-state and time-resolved fluorescence spectroscopy techniques. Interaction between the clay particles and the cationic dye compounds in aqueous solution resulted in significant changes in spectral properties of PyY compared to its molecular behavior in deionized water at the same concentration. These changes were due to the formation of dimer and aggregate of PyY in the clay suspension as well as the presence of the dye monomer. The H-type aggregates of PyY in the clay suspension were identified by the observation of a blue-shifted absorption band of the dye compared to that of its monomer. In spite of diluted dye concentrations, the H-aggregate of PyY in the clay suspension was formed. The intensive aggregation in the clay suspension attributed to the localized high dye concentration on the negatively charged clay surfaces. Adsorption sites of PyY on the clay particles were discussed by deconvulated absorption and excitation spectra. Fluorescence spectroscopy studies revealed that the fluorescence intensity of PyY in the clay suspension is decreased by H-aggregates drastically. Moreover, the presence of H-aggregates in the clay suspension resulted in the decrease of fluorescence lifetime and quantum yield of PyY compared to those in deionized water. - Highlights: → Molecular behavior of PyY adsorbed on clay surface was followed spectroscopically. → H-aggregates of PyY in the clay suspension were formed at very low dye concentrations. → The intensive H-aggregate structure drastically reduced the fluorescence intensity of PyY. → The fluorescence lifetime and quantum yield of PyY in the clay suspension was discussed.

Phenotypes of non-attached Pseudomonas aeruginosa aggregates resemble surface attached biofilm.

Directory of Open Access Journals (Sweden)

Morten Alhede

Full Text Available For a chronic infection to be established, bacteria must be able to cope with hostile conditions such as low iron levels, oxidative stress, and clearance by the host defense, as well as antibiotic treatment. It is generally accepted that biofilm formation facilitates tolerance to these adverse conditions. However, microscopic investigations of samples isolated from sites of chronic infections seem to suggest that some bacteria do not need to be attached to surfaces in order to establish chronic infections. In this study we employed scanning electron microscopy, confocal laser scanning microscopy, RT-PCR as well as traditional culturing techniques to study the properties of Pseudomonas aeruginosa aggregates. We found that non-attached aggregates from stationary-phase cultures have comparable growth rates to surface attached biofilms. The growth rate estimations indicated that, independently of age, both aggregates and flow-cell biofilm had the same slow growth rate as a stationary phase shaking cultures. Internal structures of the aggregates matrix components and their capacity to survive otherwise lethal treatments with antibiotics (referred to as tolerance and resistance to phagocytes were also found to be strikingly similar to flow-cell biofilms. Our data indicate that the tolerance of both biofilms and non-attached aggregates towards antibiotics is reversible by physical disruption. We provide evidence that the antibiotic tolerance is likely to be dependent on both the physiological states of the aggregates and particular matrix components. Bacterial surface-attachment and subsequent biofilm formation are considered hallmarks of the capacity of microbes to cause persistent infections. We have observed non-attached aggregates in the lungs of cystic fibrosis patients; otitis media; soft tissue fillers and non-healing wounds, and we propose that aggregated cells exhibit enhanced survival in the hostile host environment, compared with non-aggregated

Effect of the LHCII pigment-protein complex aggregation on photovoltaic properties of sensitized TiO2 solar cells.

Science.gov (United States)

Yang, Yiqun; Jankowiak, Ryszard; Lin, Chen; Pawlak, Krzysztof; Reus, Michael; Holzwarth, Alfred R; Li, Jun

2014-10-14

A modified dye-sensitized solar cell consisting of a thin TiO2 barrier layer sensitized with natural trimeric light-harvesting complex II (LHCII) from spinach was used as a biomimetic model to study the effects of LHCII aggregation on the photovoltaic properties. The aggregation of individual trimers induced molecular reorganization, which dramatically increased the photocurrent. The morphology of small- and large-size LHCII aggregates deposited on a surface was confirmed by atomic force microscopy. Enhanced LHCII immobilization was accomplished via electrostatic interaction with amine-functionalized photoanodes. The photocurrent responses of the assembled solar cells under illumination at three characteristic wavelength bands in the UV-Vis absorption spectra of LHCII solutions confirmed that a significant photocurrent was generated by LHCII photosensitizers. The enhanced photocurrent by large aggregated LHCII is shown to correlate with the quenching in the far-red fluorescence deriving from chlorophyll-chlorophyll charge transfer states that are effectively coupled with the TiO2 surface and thus inject electrons into the TiO2 conduction band. The large aggregated LHCII with more chlorophyll-chlorophyll charge transfer states is a much better sensitizer since it injects electrons more efficiently into the conduction band of TiO2 than the small aggregated LHCII mostly consisting of unquenched chlorophyll excited state. The assembled solar cells demonstrated remarkable stability in both aqueous buffer and acetonitrile electrolytes over 30 days.

Research on Judgment Aggregation Based on Logic

Directory of Open Access Journals (Sweden)

Li Dai

2014-05-01

Full Text Available Preference aggregation and judgment aggregation are two basic research models of group decision making. And preference aggregation has been deeply studied in social choice theory. However, researches of social choice theory gradually focus on judgment aggregation which appears recently. Judgment aggregation focuses on how to aggregate many consistent logical formulas into one, from the perspective of logic. We try to start with judgment aggregation model based on logic and then explore different solutions to problem of judgment aggregation.

A 31-residue peptide induces aggregation of tau's microtubule-binding region in cells

Science.gov (United States)

Stöhr, Jan; Wu, Haifan; Nick, Mimi; Wu, Yibing; Bhate, Manasi; Condello, Carlo; Johnson, Noah; Rodgers, Jeffrey; Lemmin, Thomas; Acharya, Srabasti; Becker, Julia; Robinson, Kathleen; Kelly, Mark J. S.; Gai, Feng; Stubbs, Gerald; Prusiner, Stanley B.; Degrado, William F.

2017-09-01

The self-propagation of misfolded conformations of tau underlies neurodegenerative diseases, including Alzheimer's. There is considerable interest in discovering the minimal sequence and active conformational nucleus that defines this self-propagating event. The microtubule-binding region, spanning residues 244-372, reproduces much of the aggregation behaviour of tau in cells and animal models. Further dissection of the amyloid-forming region to a hexapeptide from the third microtubule-binding repeat resulted in a peptide that rapidly forms fibrils in vitro. We show that this peptide lacks the ability to seed aggregation of tau244-372 in cells. However, as the hexapeptide is gradually extended to 31 residues, the peptides aggregate more slowly and gain potent activity to induce aggregation of tau244-372 in cells. X-ray fibre diffraction, hydrogen-deuterium exchange and solid-state NMR studies map the beta-forming region to a 25-residue sequence. Thus, the nucleus for self-propagating aggregation of tau244-372 in cells is packaged in a remarkably small peptide.

The Suborbital Particle Aggregation and Collision Experiment (SPACE): studying the collision behavior of submillimeter-sized dust aggregates on the suborbital rocket flight REXUS 12.

Science.gov (United States)

Brisset, Julie; Heißelmann, Daniel; Kothe, Stefan; Weidling, René; Blum, Jürgen

2013-09-01

The Suborbital Particle Aggregation and Collision Experiment (SPACE) is a novel approach to study the collision properties of submillimeter-sized, highly porous dust aggregates. The experiment was designed, built, and carried out to increase our knowledge about the processes dominating the first phase of planet formation. During this phase, the growth of planetary precursors occurs by agglomeration of micrometer-sized dust grains into aggregates of at least millimeters to centimeters in size. However, the formation of larger bodies from the so-formed building blocks is not yet fully understood. Recent numerical models on dust growth lack a particular support by experimental studies in the size range of submillimeters, because these particles are predicted to collide at very gentle relative velocities of below 1 cm/s that can only be achieved in a reduced-gravity environment. The SPACE experiment investigates the collision behavior of an ensemble of silicate-dust aggregates inside several evacuated glass containers which are being agitated by a shaker to induce the desired collisions at chosen velocities. The dust aggregates are being observed by a high-speed camera, allowing for the determination of the collision properties of the protoplanetary dust analog material. The data obtained from the suborbital flight with the REXUS (Rocket Experiments for University Students) 12 rocket will be directly implemented into a state-of-the-art dust growth and collision model.

Foam stabilization by solid particle aggregates

Energy Technology Data Exchange (ETDEWEB)

Guignot, S.; Faure, S. [CEA Marcoule, Lab. des Procedes Avances de Decontamination, 30 (France); Pitois, O. [UniversiteParis-Est Marne-La-Valle, Lab. Physique des Materiaux Divises et des Interfaces (LPMDI), 77 - Marne la Vallee (France)

2008-07-01

During the dismantling of nuclear facilities, radioactive deposits on exposed areas are removed and solubilized by successive rinses of reactive liquid. Using this liquid in a foam state reduces the amount of resulting wastes. During the required decontamination time (1 to 5 hours) the foam has to be sufficiently wet (1). In the Laboratory of Advanced Processes for Decontamination, new formulations are currently studied to slow down the drainage kinetics of these foams, by adding colloidal particles of hydrophilic fumed silica into the classical mixtures of well-defined non ionic foaming surfactants previously used (2). The objective of our study is to shed light on the foam surprising stability induced by these particles. The study focuses on drainage of foams generated by air sparging through a suspension lying on a porous glass. The foaming suspensions contain between 0 and 70 g.L-1 of a fumed silica (Aerosil 380) which is well-known to form gels for concentrations above 200 g.L{sup -1}. In the studied solutions this silica builds up into aggregates of dozens of microns, whose volume-averaged mean diameter after sonication is centred around 300 nm. Under gentle stirring, they display no sign of re-aggregation during 24 h. On a free drainage configuration, a foam that contains particles keeps a significant amount of its initial liquid: up to 60 % during up to 5 hours, in contrast to classical foams that drain out all of their liquid in about 20 minutes. From a rheological point of view, the most concentrated suspensions display a yield stress behaviour. This evidences the structuring of the aggregates into a coherent network that might explain the incomplete drainage of the solutions. For the lowest concentrated solutions, such rheological properties have not been observed although the corresponding foams can retain large amount of solution. This suggests that local concentrations of aggregates can rise owing to their retention by foam channels, until they form

Heating of Porous Icy Dust Aggregates

Energy Technology Data Exchange (ETDEWEB)

Sirono, Sin-iti [Earth and Environmental Sciences, Nagoya University, Tikusa-ku, Furo-cho, Nagoya 464-8601 (Japan)

2017-06-10

At the beginning of planetary formation, highly porous dust aggregates are formed through coagulation of dust grains. Outside the snowline, the main component of an aggregate is H{sub 2}O ice. Because H{sub 2}O ice is formed in amorphous form, its thermal conductivity is extremely small. Therefore, the thermal conductivity of an icy dust aggregate is low. There is a possibility of heating inside an aggregate owing to the decay of radionuclides. It is shown that the temperature increases substantially inside an aggregate, leading to crystallization of amorphous ice. During the crystallization, the temperature further increases sufficiently to continue sintering. The mechanical properties of icy dust aggregates change, and the collisional evolution of dust aggregates is affected by the sintering.

Compressive Strength of Concrete made from Natural Fine Aggregate Sources in Minna, Nigeria

Directory of Open Access Journals (Sweden)

M. Abdullahi

2017-12-01

Full Text Available This work presented an investigation of concrete developed from five fine aggregate sources in Minna, Niger state, Nigeria. Tests conducted on the fine aggregate samples included specific gravity, sieve analysis, bulk density and moisture content. The concrete mix design was done using absolute volume method at various mix proportion of 1:2:4, 1:2:3 and 1:1:2 and water-cement ratios of 0.4, 0.45, 0.5, 0.55 and 0.6. The compressive strengths of concrete were determined at 28-day curing age. Test results revealed that the specific gravities of the aggregate were between 2.60 to 2.70, compacted bulk densities also ranged from 1505.18 to 1701.15kg/m3, loose bulk densities ranged from 1379.32 to 1478.17kg/m3, and moisture content ranged from 0.93 to 2.47%. All the fine aggregate samples satisfied the overall and medium grading limits for natural fine aggregates. The coarse aggregate used fairly followed the grading limit for aggregate size of 20 to 5 mm. The compressive strength of the concrete obtained using the aggregate samples A, B, C, D, and Eall within the ranges of 18.97 to 34.98 N/mm2. Statistical models were developed for the compressive strength of concrete as a function of water-cement ratio for various fine aggregate sources and mix proportions. The models were found to have good predictive the capabilities of the compressive strength of concrete for given water-cement ratio. The properties of fine aggregates and the resulting concrete characteristics showed that all the fine aggregate samples are suitable to be used for concrete production.

GENERAL: Kinetic Behaviors of Catalysis-Driven Growth of Three-Species Aggregates on Base of Exchange-Driven Aggregations

Science.gov (United States)

Sun, Yun-Fei; Chen, Dan; Lin, Zhen-Quan; Ke, Jian-Hong

2009-06-01

We propose a solvable aggregation model to mimic the evolution of population A, asset B, and the quantifiable resource C in a society. In this system, the population and asset aggregates themselves grow through self-exchanges with the rate kernels K1(k, j) = K1kj and K2(k, j) = K2kj, respectively. The actions of the population and asset aggregations on the aggregation evolution of resource aggregates are described by the population-catalyzed monomer death of resource aggregates and asset-catalyzed monomer birth of resource aggregates with the rate kernels J1(k, j) = J1k and J2(k, j) = J2k, respectively. Meanwhile, the asset and resource aggregates conjunctly catalyze the monomer birth of population aggregates with the rate kernel I1(k, i, j) = I1kiμjη, and population and resource aggregates conjunctly catalyze the monomer birth of asset aggregates with the rate kernel I2(k, i, j) = I2kivjη. The kinetic behaviors of species A, B, and C are investigated by means of the mean-field rate equation approach. The effects of the population-catalyzed death and asset-catalyzed birth on the evolution of resource aggregates based on the self-exchanges of population and asset appear in effective forms. The coefficients of the effective population-catalyzed death and the asset-catalyzed birth are expressed as J1e = J1/K1 and J2e = J2/K2, respectively. The aggregate size distribution of C species is found to be crucially dominated by the competition between the effective death and the effective birth. It satisfies the conventional scaling form, generalized scaling form, and modified scaling form in the cases of J1e J2e, respectively. Meanwhile, we also find the aggregate size distributions of populations and assets both fall into two distinct categories for different parameters μ, ν, and η: (i) When μ = ν = η = 0 and μ = ν = 0, η = 1, the population and asset aggregates obey the generalized scaling forms; and (ii) When μ = ν = 1, η = 0, and μ = ν = η = 1, the

Native aggregation as a cause of origin of temporary cellular structures needed for all forms of cellular activity, signaling and transformations.

Science.gov (United States)

Matveev, Vladimir V

2010-06-09

According to the hypothesis explored in this paper, native aggregation is genetically controlled (programmed) reversible aggregation that occurs when interacting proteins form new temporary structures through highly specific interactions. It is assumed that Anfinsen's dogma may be extended to protein aggregation: composition and amino acid sequence determine not only the secondary and tertiary structure of single protein, but also the structure of protein aggregates (associates). Cell function is considered as a transition between two states (two states model), the resting state and state of activity (this applies to the cell as a whole and to its individual structures). In the resting state, the key proteins are found in the following inactive forms: natively unfolded and globular. When the cell is activated, secondary structures appear in natively unfolded proteins (including unfolded regions in other proteins), and globular proteins begin to melt and their secondary structures become available for interaction with the secondary structures of other proteins. These temporary secondary structures provide a means for highly specific interactions between proteins. As a result, native aggregation creates temporary structures necessary for cell activity."One of the principal objects of theoretical research in any department of knowledge is to find the point of view from which the subject appears in its greatest simplicity."Josiah Willard Gibbs (1839-1903).

Replacing gasoline with corn ethanol results in significant environmental problem-shifting.

Science.gov (United States)

Yang, Yi; Bae, Junghan; Kim, Junbeum; Suh, Sangwon

2012-04-03

Previous studies on the life-cycle environmental impacts of corn ethanol and gasoline focused almost exclusively on energy balance and greenhouse gas (GHG) emissions and largely overlooked the influence of regional differences in agricultural practices. This study compares the environmental impact of gasoline and E85 taking into consideration 12 different environmental impacts and regional differences among 19 corn-growing states. Results show that E85 does not outperform gasoline when a wide spectrum of impacts is considered. If the impacts are aggregated using weights developed by the National Institute of Standards and Technology (NIST), overall, E85 generates approximately 6% to 108% (23% on average) greater impact compared with gasoline, depending on where corn is produced, primarily because corn production induces significant eutrophication impacts and requires intensive irrigation. If GHG emissions from the indirect land use changes are considered, the differences increase to between 16% and 118% (33% on average). Our study indicates that replacing gasoline with corn ethanol may only result in shifting the net environmental impacts primarily toward increased eutrophication and greater water scarcity. These results suggest that the environmental criteria used in the Energy Independence and Security Act (EISA) be re-evaluated to include additional categories of environmental impact beyond GHG emissions.

Model for amorphous aggregation processes

Science.gov (United States)

Stranks, Samuel D.; Ecroyd, Heath; van Sluyter, Steven; Waters, Elizabeth J.; Carver, John A.; von Smekal, Lorenz

2009-11-01

The amorphous aggregation of proteins is associated with many phenomena, ranging from the formation of protein wine haze to the development of cataract in the eye lens and the precipitation of recombinant proteins during their expression and purification. While much literature exists describing models for linear protein aggregation, such as amyloid fibril formation, there are few reports of models which address amorphous aggregation. Here, we propose a model to describe the amorphous aggregation of proteins which is also more widely applicable to other situations where a similar process occurs, such as in the formation of colloids and nanoclusters. As first applications of the model, we have tested it against experimental turbidimetry data of three proteins relevant to the wine industry and biochemistry, namely, thaumatin, a thaumatinlike protein, and α -lactalbumin. The model is very robust and describes amorphous experimental data to a high degree of accuracy. Details about the aggregation process, such as shape parameters of the aggregates and rate constants, can also be extracted.

Whispering gallery mode emission from a composite system of J-aggregates and photonic microcavity

Energy Technology Data Exchange (ETDEWEB)

Melnikau, Dzmitry; Savateeva, Diana [Centro de Física de Materiales (MPC, CSIC-UPV/EHU) and Donostia International Physics Center (DIPC), Po Manuel de Lardizabal 5, Donostia, San Sebastian 20018 (Spain); Rusakov, Konstantin I. [Department of Physics, Brest State Technical University, Brest 224017 (Belarus); Rakovich, Yury P., E-mail: Yury.Rakovich@ehu.es [Centro de Física de Materiales (MPC, CSIC-UPV/EHU) and Donostia International Physics Center (DIPC), Po Manuel de Lardizabal 5, Donostia, San Sebastian 20018 (Spain); IKERBASQUE, Basque Foundation for Science, Bilbao (Spain)

2014-01-15

We report on development and characterization of Whispering Gallery Modes spherical microcavities integrated with organic dye molecules in a J-aggregate state. The microcavities are studied using micro-photoluminescence spectroscopy, and fluorescence lifetime imaging confocal microscopy. Directional emission of light from the microcavity is also experimentally demonstrated and attributed to the photonic jets generated in the microsphere. -- Highlights: • Report on the development and characterization of hybrid system consisting of thin shell of J-aggregates and spherical Whispering Gallery Mode microcavity. • An investigation of spontaneous emission rate in the shell of J-aggregates integrated with a Whispering Gallery Mode cavity. • Demonstration of directional emission from Whispering Gallery Mode cavity with J-aggregates which is highly desirable functionality for both micro- and nano-scale cavities.

Hip joint replacement

Science.gov (United States)

Hip arthroplasty; Total hip replacement; Hip hemiarthroplasty; Arthritis - hip replacement; Osteoarthritis - hip replacement ... Your hip joint is made up of 2 major parts. One or both parts may be replaced during surgery: ...

Experimental study of optimal self compacting concrete with spent foundry sand as partial replacement for M-sand using Taguchi approach

Directory of Open Access Journals (Sweden)

Nirmala D.B.

2016-06-01

Full Text Available This paper presents the application of Taguchi approach to obtain optimal mix proportion for Self Compacting Concrete (SCC containing spent foundry sand and M-sand. Spent foundry sand is used as a partial replacement for M-sand. The SCC mix has seven control factors namely, Coarse aggregate, M-sand with Spent Foundry sand, Cement, Fly ash, Water, Super plasticizer and Viscosity modifying agent. Modified Nan Su method is used to proportion the initial SCC mix. L18 (21×37 Orthogonal Arrays (OA with the seven control factors having 3 levels is used in Taguchi approach which resulted in 18 SCC mix proportions. All mixtures are extensively tested both in fresh and hardened states to verify whether they meet the practical and technical requirements of SCC. The quality characteristics considering “Nominal the better” situation is applied to the test results to arrive at the optimal SCC mix proportion. Test results indicate that the optimal mix satisfies the requirements of fresh and hardened properties of SCC. The study reveals the feasibility of using spent foundry sand as a partial replacement of M-sand in SCC and also that Taguchi method is a reliable tool to arrive at optimal mix proportion of SCC.

Experimental study of optimal self compacting concrete with spent foundry sand as partial replacement for M-sand using Taguchi approach

Science.gov (United States)

Nirmala, D. B.; Raviraj, S.

2016-06-01

This paper presents the application of Taguchi approach to obtain optimal mix proportion for Self Compacting Concrete (SCC) containing spent foundry sand and M-sand. Spent foundry sand is used as a partial replacement for M-sand. The SCC mix has seven control factors namely, Coarse aggregate, M-sand with Spent Foundry sand, Cement, Fly ash, Water, Super plasticizer and Viscosity modifying agent. Modified Nan Su method is used to proportion the initial SCC mix. L18 (21×37) Orthogonal Arrays (OA) with the seven control factors having 3 levels is used in Taguchi approach which resulted in 18 SCC mix proportions. All mixtures are extensively tested both in fresh and hardened states to verify whether they meet the practical and technical requirements of SCC. The quality characteristics considering "Nominal the better" situation is applied to the test results to arrive at the optimal SCC mix proportion. Test results indicate that the optimal mix satisfies the requirements of fresh and hardened properties of SCC. The study reveals the feasibility of using spent foundry sand as a partial replacement of M-sand in SCC and also that Taguchi method is a reliable tool to arrive at optimal mix proportion of SCC.

A comparative study on the aggregating effects of guanidine thiocyanate, guanidine hydrochloride and urea on lysozyme aggregation

Energy Technology Data Exchange (ETDEWEB)

Emadi, Saeed, E-mail: emadi@iasbs.ac.ir; Behzadi, Maliheh

2014-08-08

Highlights: • Lysozyme aggregated in guanidine thiocyanate (1.0 and 2.0 M). • Lysozyme aggregated in guanidine hydrochloride (4 and 5 M). • Lysozyme did not aggregated at any concentration (0.5–5 M) of urea. • Unfolding pathway is more important than unfolding per se in aggregation. - Abstract: Protein aggregation and its subsequent deposition in different tissues culminate in a diverse range of diseases collectively known as amyloidoses. Aggregation of hen or human lysozyme depends on certain conditions, namely acidic pH or the presence of additives. In the present study, the effects on the aggregation of hen egg-white lysozyme via incubation in concentrated solutions of three different chaotropic agents namely guanidine thiocyanate, guanidine hydrochloride and urea were investigated. Here we used three different methods for the detection of the aggregates, thioflavin T fluorescence, circular dichroism spectroscopy and atomic force microscopy. Our results showed that upon incubation with different concentrations (0.5, 1.0, 2.0, 3.0, 4.0, 5.0 M) of the chemical denaturants, lysozyme was aggregated at low concentrations of guanidine thiocyanate (1.0 and 2.0 M) and at high concentrations of guanidine hydrochloride (4 and 5 M), although no fibril formation was detected. In the case of urea, no aggregation was observed at any concentration.

Application of the index WQI-CCME with data aggregation per monitoring campaign and per section of the river: case study-Joanes River, Brazil.

Science.gov (United States)

de Almeida, Geane Silva; de Oliveira, Iara Brandão

2018-03-07

This work applied the Water Quality Index developed by the Canadian Council of Ministers of the Environment (WQI-CCME), to communicate the water quality per section of the Joanes River basin, State of Bahia, Brazil. WQI-CCME is a statistical procedure that originally requires the execution of at least four monitoring campaigns per monitoring location and the measurement of at least four parameters. This paper presents a new aggregation method to calculate the WQI-CCME because, to apply the original method in Joanes River, a huge loss of information would occur, by the fact that, the number of analyzed parameters varied between the monitoring campaigns developed by the Government Monitoring Program. This work modified the original aggregation method replacing it by a data aggregation for a single monitoring campaign, in a minimum of four monitoring locations per section of the river and a minimum of four parameters per monitoring location. Comparison between the calculation of WQI-CCME for river sections, with the index, WQI-CETESB, developed by the Brazilian Environmental Sanitation and Technology Company-CETESB, proved the applicability of the new aggregation method. The WQI-CETESB has it bases on the WQI from the National Sanitation Foundation and uses nine fixed parameters. As WQI-CCME uses the totality of the analyzed parameters without restrictions, it is more flexible, and the results seem more adequate to indicate the real river water quality. However, the WQI-CCME has a more stringent water quality scale in comparison with the WQI-CETESB, resulting in inferior water quality information. In conclusion, the WQI-CCME with a new aggregation method is adequate for communicating the water quality at a given time, per section of a river, respecting the minimum number of four analyses and four monitoring points. As a result, without a need to wait for other campaigns, it reduces the cost of a monitoring program and the period to communicate the water quality. The

Properties of palm oil fuel ash cement sand brick containing pulverized cockle shell as partial sand replacement

Science.gov (United States)

Mat Aris, S.; Muthusamy, K.; Uzer, A.; Ahmad, S. Wan

2018-04-01

Environmental pollution caused by the disposal of solid wastes generated from both palm oil industry and cockle shell trade has motivated researches to explore the potential of these wastes. Integrating these wastes in production of construction material is one of the ways to reduce amount of waste thrown at dumping area. Thus, the present investigation investigates the performance of palm oil fuel ash (POFA) cement sand brick containing pulverized cockle shell as partial fine aggregate replacement. All mixes used contain 20% of POFA as partial cement replacement. Total of six mixes were prepared by adding a range of pulverized cockle shell that is 0%, 10%, 20%, 30%, 40% and 50% as partial sand replacement. The mixes were prepared in form of brick. All the water cured samples were tested for compressive strength and flexural strength until 28 days. Findings show that brick produced using 20% pulverized cockle shell exhibit the highest compressive strength and flexural strength also the lowest water absorption value.

An eco-friendly self-compacting concrete with recycled coarse aggregates

Directory of Open Access Journals (Sweden)

Pereira-de Oliveira, L. A.

2013-09-01

Full Text Available The potential uses of coarse recycled aggregates in the composition of SCC increases the ecological value and partly solve the issues of waste disposal sites generated by construction and demolition of structures. Thus, this paper present an experimental study of SCC properties where the normal coarse aggregates were replaced by different percentages of recycled aggregates, i.e., 0% (SCC, 10% (SCCR10, 20% (SCCR20, 30% (SCCR30 and 40% (SCCR40. The results from fresh concrete (rheological properties and self-compactability as the hardened concrete properties (compressive strength, density and dynamic modulus of elasticity, show only minor discrepancies. From the standpoint of mechanical behaviour, the results confirm the viability to incorporate coarse recycled aggregates in the SCC demonstrating the conservative character of the currently recommended limits.Los usos potenciales de áridos gruesos reciclados en la composición del hormigón autocompactante (SCC aumenta el valor ecológico y en parte resuelve los problemas de los sitios de disposición de residuos generados por la construcción y la demolición de las estructuras. Por lo tanto, este trabajo presenta un estudio experimental de las propiedades de SCC en el cual los áridos gruesos naturales fueron reemplazados por distintos porcentajes de áridos reciclados, es decir, 0% (SCC, el 10% (SCCR10, el 20% (SCCR20, el 30% (SCCR30 y el 40% (SCCR40. Los resultados del hormigón fresco (propiedades reológicas y la auto-compactación, como las propiedades de hormigón endurecido (resistencia a la compresión, densidad y módulo de elasticidad dinámico, muestran sólo pequeñas discrepancias. Desde el punto de vista del comportamiento mecánico, los resultados confirman la viabilidad de incorporar áridos gruesos reciclados en los SCC demostrando el carácter conservador de los límites actualmente recomendados.

Essential Specification Elements for Heat Exchanger Replacement

Energy Technology Data Exchange (ETDEWEB)

Bower, L.

2015-07-01

Performance upgrade and equipment degradation are the primary impetuses for a nuclear power plant to engage in the large capital cost project of heat exchanger replacement. Along with attention to these issues, consideration of heat exchanger Codes and Standards, material improvements, thermal redesign, and configuration are essential for developing User’s Design Specifications for successful replacement projects. The User’s Design Specification is the central document in procuring ASME heat exchangers. Properly stated objectives for the heat exchanger replacement are essential for obtaining the materials, configurations and thermal designs best suited for the nuclear power plant. Additionally, the code of construction required and the applied manufacturing standard (TEMA or HEI) affects how the heat exchanger may be designed or configured to meet the replacement goals. Knowledge of how Codes and Standards affect design and configuration details will aid in writing the User’s Design Specification. Joseph Oat Corporation has designed and fabricated many replacement heat exchangers for the nuclear power industry. These heat exchangers have been constructed per ASME Section III to various Code-Years or ASME Section VIII-1 to the current Code-Year also in accordance with TEMA and HEI. These heat exchangers have been a range of like-for-like replacement to complete thermal, material and configuration redesigns. Several examples of these heat exchangers with their Code, Standard and specification implications are presented. (Author.

Influence of granitic aggregates from Northeast Brazil on the alkali-aggregate reaction

Energy Technology Data Exchange (ETDEWEB)

Gomes Neto, David de Paiva; Santana, Rodrigo Soares de; Barreto, Ledjane Silva, E-mail: pvgomes@uol.com.br [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Ciencias dos Materiais e Engenharia; Conceicao, Herbert; Lisboa, Vinicios Anselmo Carvalho [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Geologia

2014-08-15

The alkali-aggregate reaction (AAR) in concrete structures is a problem that has concerned engineers and researchers for decades. This reaction occurs when silicates in the aggregates react with the alkalis, forming an expanded gel that can cause cracks in the concrete and reduce its lifespan. The aim of this study was to characterize three coarse granitic aggregates employed in concrete production in northeastern Brazil, correlating petrographic analysis with the kinetics of silica dissolution and the evolution of expansions in mortar bars, assisted by SEM/EDS, XRD, and EDX. The presence of grains showing recrystallization into individual microcrystalline quartz subgrains was associated with faster dissolution of silica and greater expansion in mortar bars. Aggregates showing substantial deformation, such as stretched grains of quartz with strong undulatory extinction, experienced slower dissolution, with reaction and expansion occurring over longer periods that could not be detected using accelerated tests with mortar bars. (author)

Modification of strength properties of soil-aggregate system on ...

African Journals Online (AJOL)

Introduction. India is currently having a road network of 4.69 million kilometers. ... National Highways and State Highways, comprising only 3% of total road length, each carrying ... Two types of mixtures are specified in the code for soil – aggregate ..... performance of sabkha subgrade, Building and Environment, Vol. 41, No.

Will mineral trioxide aggregate replace calcium hydroxide in treating pulpal and periodontal healing complications subsequent to dental trauma?

DEFF Research Database (Denmark)

Bakland, Leif K; Andreasen, Jens O

2012-01-01

Mineral trioxide aggregate (MTA) has over the last two decades begun to take the place of calcium hydroxide (CH) in the treatment of a variety of pulpal and periodontal healing complications following dental trauma. These conditions include teeth with: (i) exposed pulps, (ii) immature roots......, the quality of such induced hard tissues, and finally the dentin weakening effect of CH, which in some instances lead to cervical root fractures in immature teeth. MTA appears, from a relatively few clinical studies, to overcome these shortcomings of CH. The lack of long-term clinical studies, however, may...

Political Participation Online: The Replacement and the Mobilisation Hypotheses Revisited

DEFF Research Database (Denmark)

Jensen, Jakob Linaa

2013-01-01

This article discusses the state of political participation online more than ten years after the Internet’s great popular breakthrough as an everyday medium. Denmark is used as a case study to critically re-examine the frequently discussed replacement and mobilisation hypotheses on behalf of the ...... participation, efficacy and social capital seem to have less impact on online political participation. In the end, these findings are related to more overall discussions on the democratising potential of the Internet.......This article discusses the state of political participation online more than ten years after the Internet’s great popular breakthrough as an everyday medium. Denmark is used as a case study to critically re-examine the frequently discussed replacement and mobilisation hypotheses on behalf...... of the Internet. The pure replacement hypothesis is rejected. Instead, it is found that the Internet still supplements rather than replaces other media, even among heavy Internet users. The Internet is one among several media used by ‘media omnivores’, and political participation online supplements rather than...

Graph Theory and Ion and Molecular Aggregation in Aqueous Solutions

Science.gov (United States)

Choi, Jun-Ho; Lee, Hochan; Choi, Hyung Ran; Cho, Minhaeng

2018-04-01

In molecular and cellular biology, dissolved ions and molecules have decisive effects on chemical and biological reactions, conformational stabilities, and functions of small to large biomolecules. Despite major efforts, the current state of understanding of the effects of specific ions, osmolytes, and bioprotecting sugars on the structure and dynamics of water H-bonding networks and proteins is not yet satisfactory. Recently, to gain deeper insight into this subject, we studied various aggregation processes of ions and molecules in high-concentration salt, osmolyte, and sugar solutions with time-resolved vibrational spectroscopy and molecular dynamics simulation methods. It turns out that ions (or solute molecules) have a strong propensity to self-assemble into large and polydisperse aggregates that affect both local and long-range water H-bonding structures. In particular, we have shown that graph-theoretical approaches can be used to elucidate morphological characteristics of large aggregates in various aqueous salt, osmolyte, and sugar solutions. When ion and molecular aggregates in such aqueous solutions are treated as graphs, a variety of graph-theoretical properties, such as graph spectrum, degree distribution, clustering coefficient, minimum path length, and graph entropy, can be directly calculated by considering an ensemble of configurations taken from molecular dynamics trajectories. Here we show percolating behavior exhibited by ion and molecular aggregates upon increase in solute concentration in high solute concentrations and discuss compelling evidence of the isomorphic relation between percolation transitions of ion and molecular aggregates and water H-bonding networks. We anticipate that the combination of graph theory and molecular dynamics simulation methods will be of exceptional use in achieving a deeper understanding of the fundamental physical chemistry of dissolution and in describing the interplay between the self-aggregation of solute

Graph Theory and Ion and Molecular Aggregation in Aqueous Solutions.

Science.gov (United States)

Choi, Jun-Ho; Lee, Hochan; Choi, Hyung Ran; Cho, Minhaeng

2018-04-20

In molecular and cellular biology, dissolved ions and molecules have decisive effects on chemical and biological reactions, conformational stabilities, and functions of small to large biomolecules. Despite major efforts, the current state of understanding of the effects of specific ions, osmolytes, and bioprotecting sugars on the structure and dynamics of water H-bonding networks and proteins is not yet satisfactory. Recently, to gain deeper insight into this subject, we studied various aggregation processes of ions and molecules in high-concentration salt, osmolyte, and sugar solutions with time-resolved vibrational spectroscopy and molecular dynamics simulation methods. It turns out that ions (or solute molecules) have a strong propensity to self-assemble into large and polydisperse aggregates that affect both local and long-range water H-bonding structures. In particular, we have shown that graph-theoretical approaches can be used to elucidate morphological characteristics of large aggregates in various aqueous salt, osmolyte, and sugar solutions. When ion and molecular aggregates in such aqueous solutions are treated as graphs, a variety of graph-theoretical properties, such as graph spectrum, degree distribution, clustering coefficient, minimum path length, and graph entropy, can be directly calculated by considering an ensemble of configurations taken from molecular dynamics trajectories. Here we show percolating behavior exhibited by ion and molecular aggregates upon increase in solute concentration in high solute concentrations and discuss compelling evidence of the isomorphic relation between percolation transitions of ion and molecular aggregates and water H-bonding networks. We anticipate that the combination of graph theory and molecular dynamics simulation methods will be of exceptional use in achieving a deeper understanding of the fundamental physical chemistry of dissolution and in describing the interplay between the self-aggregation of solute

Fractal Aggregates in Tennis Ball Systems

Science.gov (United States)

Sabin, J.; Bandin, M.; Prieto, G.; Sarmiento, F.

2009-01-01

We present a new practical exercise to explain the mechanisms of aggregation of some colloids which are otherwise not easy to understand. We have used tennis balls to simulate, in a visual way, the aggregation of colloids under reaction-limited colloid aggregation (RLCA) and diffusion-limited colloid aggregation (DLCA) regimes. We have used the…

A Functional Reference Architecture for Aggregators

DEFF Research Database (Denmark)

Bondy, Daniel Esteban Morales; Heussen, Kai; Gehrke, Oliver

2015-01-01

Aggregators are considered to be a key enabling technology for harvesting power system services from distributed energy resources (DER). As a precondition for more widespread use of aggregators in power systems, methods for comparing and validating aggregator designs must be established. This paper...... proposes a functional reference architecture for aggregators to address this requirement....

The fractal character of radiation defects aggregation in crystals

International Nuclear Information System (INIS)

Akylbekov, A.; Akimbekov, E.; Baktybekov, K.; Vasil'eva, I.

2002-01-01

In processes of self-organization, which characterize open systems, the source of ordering is a non-equilibrium. One of the samples of ordering system is radiation-stimulated aggregation of defects in solids. In real work the analysis of criterions of ordering defects structures in solid, which is continuously irradiate at low temperature is presented. The method of cellular automata used in simulation of irradiation. It allowed us to imitate processes of defects formation and recombination. The simulation realized on the surfaces up to 1000x1000 units with initial concentration of defects C n (the power of dose) 0.1-1 %. The number of iterations N (duration of irradiation) mounted to 10 6 cycles. The single centers, which are the sources of formation aggregates, survive in the result of probabilistic nature of formation and recombination genetic pairs of defects and with strictly fixed radius of recombination (the minimum inter anionic distance). For determination the character of same type defects distribution the potential of their interaction depending of defects type and reciprocal distance is calculated. For more detailed study of processes, proceeding in cells with certain sizes of aggregates, the time dependence of potential interaction is constructed. It is shown, that on primary stage the potential is negative, then it increase and approach the saturation in positive area. The minimum of interaction potential corresponds to state of physical chaos in system. Its increasing occurs with formation of same type defects aggregates. Further transition to saturation and 'undulating' character of curves explains by formation and destruction aggregates. The data indicated that - these processes occur simultaneously in cells with different sizes. It allows us to assume that the radiation defects aggregation have a fractal nature

Aggregation server for grid-integrated vehicles

Science.gov (United States)

Kempton, Willett

2015-05-26

Methods, systems, and apparatus for aggregating electric power flow between an electric grid and electric vehicles are disclosed. An apparatus for aggregating power flow may include a memory and a processor coupled to the memory to receive electric vehicle equipment (EVE) attributes from a plurality of EVEs, aggregate EVE attributes, predict total available capacity based on the EVE attributes, and dispatch at least a portion of the total available capacity to the grid. Power flow may be aggregated by receiving EVE operational parameters from each EVE, aggregating the received EVE operational parameters, predicting total available capacity based on the aggregated EVE operational parameters, and dispatching at least a portion of the total available capacity to the grid.

Quality Assessment of Mixed and Ceramic Recycled Aggregates from Construction and Demolition Wastes in the Concrete Manufacture According to the Spanish Standard.

Science.gov (United States)

Rodríguez-Robles, Desirée; García-González, Julia; Juan-Valdés, Andrés; Morán-Del Pozo, Julia Mª; Guerra-Romero, Manuel I

2014-08-13

Construction and demolition waste (CDW) constitutes an increasingly significant problem in society due to the volume generated, rendering sustainable management and disposal problematic. The aim of this study is to identify a possible reuse option in the concrete manufacturing for recycled aggregates with a significant ceramic content: mixed recycled aggregates (MixRA) and ceramic recycled aggregates (CerRA). In order to do so, several tests are conducted in accordance with the Spanish Code on Structural Concrete (EHE-08) to determine the composition in weight and physic-mechanical characteristics (particle size distributions, fine content, sand equivalent, density, water absorption, flakiness index, and resistance to fragmentation) of the samples for the partial inclusion of the recycled aggregates in concrete mixes. The results of these tests clearly support the hypothesis that this type of material may be suitable for such partial replacements if simple pretreatment is carried out. Furthermore, this measure of reuse is in line with European, national, and regional policies on sustainable development, and presents a solution to the environmental problem caused by the generation of CDW.

Quality Assessment of Mixed and Ceramic Recycled Aggregates from Construction and Demolition Wastes in the Concrete Manufacture According to the Spanish Standard

Directory of Open Access Journals (Sweden)

Desirée Rodríguez-Robles

2014-08-01

Full Text Available Construction and demolition waste (CDW constitutes an increasingly significant problem in society due to the volume generated, rendering sustainable management and disposal problematic. The aim of this study is to identify a possible reuse option in the concrete manufacturing for recycled aggregates with a significant ceramic content: mixed recycled aggregates (MixRA and ceramic recycled aggregates (CerRA. In order to do so, several tests are conducted in accordance with the Spanish Code on Structural Concrete (EHE-08 to determine the composition in weight and physic-mechanical characteristics (particle size distributions, fine content, sand equivalent, density, water absorption, flakiness index, and resistance to fragmentation of the samples for the partial inclusion of the recycled aggregates in concrete mixes. The results of these tests clearly support the hypothesis that this type of material may be suitable for such partial replacements if simple pretreatment is carried out. Furthermore, this measure of reuse is in line with European, national, and regional policies on sustainable development, and presents a solution to the environmental problem caused by the generation of CDW.

A 5-year profile of the incidence of total joint replacement in South ...

African Journals Online (AJOL)

During this period there was a 28% increase in the number of TJRs performed annually with an average increase of 20% in total hip replacements and 40% in total knee replacements. The number of surgeons involved in joint replacement during the survey period decreased by 7% in state-subsidised institutions but ...

Laboratory evaluation of recycled concrete as aggregate in new concrete pavements.

Science.gov (United States)

2014-09-01

The Washington State Department of Transportation (WSDOT) has initiated a research project to investigate the use of recycled concrete as : aggregates (RCA) in Portland (hydraulic) cement concrete pavements (PCCP). The planned source for the RCA in t...

High Strength Lightweight Concrete Made with Ternary Mixtures of Cement-Fly Ash-Silica Fume and Scoria as Aggregate

OpenAIRE

YAŞAR, Ergül; ATIŞ, Cengiz Duran; KILIÇ, Alaettin

2014-01-01

This paper presents part of the results of an ongoing laboratory study carried out to design a structural lightweight high strength concrete (SLWHSC) made with and without ternary mixtures of cement-fly ash-silica fume. In the mixtures, lightweight basaltic-pumice (scoria) aggregate was used. A concrete mixture made with lightweight scoria, and another lightweight scoria concrete mixture incorporating 20% fly ash and 10% silica fume as a cement replacement, were prepared. Two normal...

Optical spectroscopy and system–bath interactions in molecular aggregates with full configuration interaction Frenkel exciton model

Energy Technology Data Exchange (ETDEWEB)

Seibt, Joachim; Sláma, Vladislav; Mančal, Tomáš, E-mail: mancal@karlov.mff.cuni.cz

2016-12-20

Highlights: • Standard Frenkel exciton model is extended to include inter-band coupling. • It is formally linked with configuration interaction method of quantum chemistry. • Spectral shifts due to inter-band coupling are found in molecular aggregates. • Effects of peak amplitude redistribution in two-dimensional spectra are found. - Abstract: Standard application of the Frenkel exciton model neglects resonance coupling between collective molecular aggregate states with different number of excitations. These inter-band coupling terms are, however, of the same magnitude as the intra-band coupling between singly excited states. We systematically derive the Frenkel exciton model from quantum chemical considerations, and identify it as a variant of the configuration interaction method. We discuss all non-negligible couplings between collective aggregate states, and provide compact formulae for their calculation. We calculate absorption spectra of molecular aggregate of carotenoids and identify significant band shifts as a result of inter-band coupling. The presence of inter-band coupling terms requires renormalization of the system–bath coupling with respect to standard formulation, but renormalization effects are found to be weak. We present detailed discussion of molecular dimer and calculate its time-resolved two-dimensional Fourier transformed spectra to find weak but noticeable effects of peak amplitude redistribution due to inter-band coupling.

Characterization and influence of fine recycled aggregates on masonry mortars properties

Directory of Open Access Journals (Sweden)

Saiz-Martínez, P.

2015-09-01

Full Text Available This research aims to study mechanical behaviour and relevant properties of masonry mortars fabricated using fine recycled aggregate in different mixture proportions. Fine recycled aggregates samples originated from the ceramic and concrete recycling process and coming from two recycling plants of Madrid region have been used. Tests were performed using 1:3:0.5 volumetric cement-to-aggregate-to-water ratio. Standardized sand with fine recycled aggregate replacement percentages were: 10%, 15%, 25%, 35% and 45%. A continuous size distribution curve can be observed and the main crystalline phases determined have been quartz, calcite and gypsum. Compressive strength, shrinkage and bond strength tests revealed poorer performance of recycled mortars compared to the conventional mortars; however, specific values are within the limits established by the manufacturers and standards. This study shows that cement-based mortars prepared with volumetric ratio 1:3:0.5 may contain up to 45% of fine recycled aggregates, without their properties being affected and without presenting significant losses.Esta investigación estudia el comportamiento mecánico y las propiedades más relevantes de los morteros de albañilería fabricados usando arenas recicladas en diferentes proporciones. Muestras pertenecientes a la línea de reciclaje cerámica y de hormigón proceden de dos centrales de reciclaje de la Comunidad de Madrid. Los ensayos se realizaron con una dosificación 1:3:0,5. Los porcentajes de arena reciclada fueron: 10%, 15%, 25%, 35% y 45%. Se observa una línea granulométrica continua y las principales fases cristalinas encontradas son cuarzo, calcita y yeso. Los ensayos de resistencia a compresión, retracción y adherencia muestran un peor comportamiento en los morteros reciclados frente a los morteros elaborados con arena normalizada, aunque dentro de los límites establecidos por normativas y fabricantes. Se deduce que, los morteros de alba

What favors convective aggregation and why?

Science.gov (United States)

Muller, Caroline; Bony, Sandrine

2015-07-01

The organization of convection is ubiquitous, but its physical understanding remains limited. One particular type of organization is the spatial self-aggregation of convection, taking the form of cloud clusters, or tropical cyclones in the presence of rotation. We show that several physical processes can give rise to self-aggregation and highlight the key features responsible for it, using idealized simulations. Longwave radiative feedbacks yield a "radiative aggregation." In that case, sufficient spatial variability of radiative cooling rates yields a low-level circulation, which induces the upgradient energy transport and radiative-convective instability. Not only do vertically integrated radiative budgets matter but the vertical profile of cooling is also crucial. Convective aggregation is facilitated when downdrafts below clouds are weak ("moisture-memory aggregation"), and this is sufficient to trigger aggregation in the absence of longwave radiative feedbacks. These results shed some light on the sensitivity of self-aggregation to various parameters, including resolution or domain size.

Social Networks: Rational Learning and Information Aggregation

Science.gov (United States)

2009-09-01

predecessor, Gale and Kariv (2003) who generalize the payoff equalization result of Bala and Goyal (1998) in connected social networks (discussed below...requires more notation. Using Bayes’ Rule and the assumption of equal priors on the state θ, we have that the social belief given by observing... Social Networks: Rational Learning and Information Aggregation by Ilan Lobel B.Sc., Pontif́ıcia Universidade Católica do Rio de Janeiro (2004

Native aggregation as a cause of origin of temporary cellular structures needed for all forms of cellular activity, signaling and transformations

Directory of Open Access Journals (Sweden)

Matveev Vladimir V

2010-06-01

Full Text Available Abstract According to the hypothesis explored in this paper, native aggregation is genetically controlled (programmed reversible aggregation that occurs when interacting proteins form new temporary structures through highly specific interactions. It is assumed that Anfinsen's dogma may be extended to protein aggregation: composition and amino acid sequence determine not only the secondary and tertiary structure of single protein, but also the structure of protein aggregates (associates. Cell function is considered as a transition between two states (two states model, the resting state and state of activity (this applies to the cell as a whole and to its individual structures. In the resting state, the key proteins are found in the following inactive forms: natively unfolded and globular. When the cell is activated, secondary structures appear in natively unfolded proteins (including unfolded regions in other proteins, and globular proteins begin to melt and their secondary structures become available for interaction with the secondary structures of other proteins. These temporary secondary structures provide a means for highly specific interactions between proteins. As a result, native aggregation creates temporary structures necessary for cell activity. "One of the principal objects of theoretical research in any department of knowledge is to find the point of view from which the subject appears in its greatest simplicity." Josiah Willard Gibbs (1839-1903