A historical review of additives and modifiers used in paving asphalt refining processes in the United States.

PubMed

Mundt, Diane J; Adams, Robert C; Marano, Kristin M

2009-11-01

The U.S. asphalt paving industry has evolved over time to meet various performance specifications for liquid petroleum asphalt binder (known as bitumen outside the United States). Additives to liquid petroleum asphalt produced in the refinery may affect exposures to workers in the hot mix paving industry. This investigation documented the changes in the composition and distribution of the liquid petroleum asphalt products produced from petroleum refining in the United States since World War II. This assessment was accomplished by reviewing documents and interviewing individual experts in the industry to identify current and historical practices. Individuals from 18 facilities were surveyed; the number of facilities reporting use of any material within a particular class ranged from none to more than half the respondents. Materials such as products of the process stream, polymers, elastomers, and anti-strip compounds have been added to liquid petroleum asphalt in the United States over the past 50 years, but modification has not been generally consistent by geography or time. Modifications made to liquid petroleum asphalt were made generally to improve performance and were dictated by state specifications.

EVALUATION OF WILDER CONSTRUCTION COMPANY'S MATCON ™ COVER TECHNOLOGY - INNOVATIVE TECHNOLOGY EVALUATION REPORT

EPA Science Inventory

MatCon is a polymer modified asphalt material designed specifically for waste containment applications. The modifications to the material differentiate it from conventional paving asphalt by minimizing the damaging effects of environmental exposure that could detract from the de...

40 CFR 443.31 - Specialized definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.31 Specialized definitions. For the purpose of... asphalt roofing materials. (c) The term “process wastewater pollutants” shall mean any pollutants present...

40 CFR 443.31 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.31 Specialized definitions. For the purpose of... asphalt roofing materials. (c) The term “process wastewater pollutants” shall mean any pollutants present...

40 CFR 443.31 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.31 Specialized definitions. For the purpose of... asphalt roofing materials. (c) The term “process wastewater pollutants” shall mean any pollutants present...

ASTM and other specifications and classifications for petroleum products and lubricants. Fifth edition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1989-01-01

This book includes specifications and classifications from ASTM committees on paint and related coatings and materials; road and paving materials; wood; roofing, waterproofing and bituminous materials; rubber; soaps and other detergents; aromatic hydrocarbons and related chemicals; and electrical insulating liquids and gases. Also included are several related, important specifications and classifications from other organizations.

Nondestructive Evaluation of Airport Pavements. Volume I. Program References,

DTIC Science & Technology

1979-09-01

greater than its original capacity (see test 13 on Fig. 2.5). During the material tests by Majidzadeh, the dynamic E-value of frozen subgrade soil was...Sample the base and subbase material by conventional spoon and identify the material by standard soil -aggregate classification and penetration...such as shaker table. The new testing specification is designed for all paving materials including subgrade soils . The specifications of material

Rapid Radiochemical Methods for Asphalt Paving Material ...

EPA Pesticide Factsheets

Technical Brief Validated rapid radiochemical methods for alpha and beta emitters in solid matrices that are commonly encountered in urban environments were previously unavailable for public use by responding laboratories. A lack of tested rapid methods would delay the quick determination of contamination levels and the assessment of acceptable site-specific exposure levels. Of special concern are matrices with rough and porous surfaces, which allow the movement of radioactive material deep into the building material making it difficult to detect. This research focuses on methods that address preparation, radiochemical separation, and analysis of asphalt paving materials and asphalt roofing shingles. These matrices, common to outdoor environments, challenge the capability and capacity of very experienced radiochemistry laboratories. Generally, routine sample preparation and dissolution techniques produce liquid samples (representative of the original sample material) that can be processed using available radiochemical methods. The asphalt materials are especially difficult because they do not readily lend themselves to these routine sample preparation and dissolution techniques. The HSRP and ORIA coordinate radiological reference laboratory priorities and activities in conjunction with HSRP’s Partner Process. As part of the collaboration, the HSRP worked with ORIA to publish rapid radioanalytical methods for selected radionuclides in building material matrice

Validation and refinement of mixture volumetric material properties identified in superpave monitoring project II : phase II : [summary].

DOT National Transportation Integrated Search

2015-02-01

Superpave is a set of methods and materials for asphalt paving and the primary method : used by the Florida Department of Transportation. It is well documented that performance : of asphalt mixtures is strongly affected by size composition of aggrega...

40 CFR 443.11 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.11 Specialized definitions. For the purpose of...

40 CFR 443.11 - Specialized definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.11 Specialized definitions. For the purpose of...

40 CFR 443.11 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.11 Specialized definitions. For the purpose of...

40 CFR 443.11 - Specialized definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.11 Specialized definitions. For the purpose of this subpart: (a...

40 CFR 443.11 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.11 Specialized definitions. For the purpose of this subpart: (a...

Bituminous Mixtures Lab

DOT National Transportation Integrated Search

2002-07-25

The Bituminous Mixtures Laboratory (BML) specializes in the research of asphalt pavement mixtures. This lab supports FHWA's efforts to develop, evaluate and improve materials, mixture design technology and performance-based tests for asphalt paving m...

40 CFR 443.16 - Pretreatment standards for new sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.16 Pretreatment standards for new sources. Any...

40 CFR 443.36 - Pretreatment standard for new sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.36 Pretreatment standard for new sources. Any...

40 CFR 443.36 - Pretreatment standard for new sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.36 Pretreatment standard for new sources. Any...

40 CFR 443.26 - Pretreatment standard for new sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.26 Pretreatment standard for new sources. Any...

40 CFR 443.16 - Pretreatment standards for new sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.16 Pretreatment standards for new sources. Any...

40 CFR 443.46 - Pretreatment standard for new sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.46 Pretreatment standard for...

40 CFR 443.26 - Pretreatment standard for new sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.26 Pretreatment standard for new sources. Any...

40 CFR 443.46 - Pretreatment standard for new sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.46 Pretreatment standard for...

Parametric study on the compressive strength geopolymer paving block

NASA Astrophysics Data System (ADS)

Aman; Awaluddin, A.; Ahmad, A.; Olivia, M.

2018-04-01

This paper reported about the investigated of sodium hidroxida concentration, effect of ratio liquid to solid (L/S), temperature and time on the compressive strength of geopolymer paving block using fly ash and fine aggregate as base material and combination of sodium hidroxida and sodium silicate as alkaline activator and the ratio of Na2SiO3/NaOH was 2 and fly ash to aggregate of 1: 3. The experiments were conducted with variation of the sodium hidroxida concentration of (10-16 M) liquid to solid (L/S) 0.1- 0.7 ratio, curing temperature 30-100 °C and curing time (7-28 day). The main evaluation techniques in this experimental were Compressive strength, X-ray diffraction (XRD),and Scaning Electron Microscope (SEM). The result showed that the compressive strength of Geopolymer Paving block has increased with an increasing of concentration, liquid to solid ratio, curing temperature and curing time.

Acoustic wayfinding: A method to measure the acoustic contrast of different paving materials for blind people.

PubMed

Secchi, Simone; Lauria, Antonio; Cellai, Gianfranco

2017-01-01

Acoustic wayfinding involves using a variety of auditory cues to create a mental map of the surrounding environment. For blind people, these auditory cues become the primary substitute for visual information in order to understand the features of the spatial context and orient themselves. This can include creating sound waves, such as tapping a cane. This paper reports the results of a research about the "acoustic contrast" parameter between paving materials functioning as a cue and the surrounding or adjacent surface functioning as a background. A number of different materials was selected in order to create a test path and a procedure was defined for the verification of the ability of blind people to distinguish different acoustic contrasts. A method is proposed for measuring acoustic contrast generated by the impact of a cane tip on the ground to provide blind people with environmental information on spatial orientation and wayfinding in urban places. Copyright © 2016 Elsevier Ltd. All rights reserved.

40 CFR 443.15 - Standards of performance for new sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.15 Standards of performance for new sources...

40 CFR 443.36 - Pretreatment standard for new sources.

Code of Federal Regulations, 2013 CFR

2013-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.36 Pretreatment standard for new sources. Any...

40 CFR 443.25 - Standards of performance for new sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.25 Standards of performance for new sources...

40 CFR 443.16 - Pretreatment standards for new sources.

Code of Federal Regulations, 2013 CFR

2013-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.16 Pretreatment standards for new sources. Any...

40 CFR 443.45 - Standards of performance for new sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.45 Standards of performance...

40 CFR 443.36 - Pretreatment standard for new sources.

Code of Federal Regulations, 2012 CFR

2012-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.36 Pretreatment standard for new sources. Any...

40 CFR 443.26 - Pretreatment standard for new sources.

Code of Federal Regulations, 2014 CFR

2014-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.26 Pretreatment standard for new sources. Any...

40 CFR 443.16 - Pretreatment standards for new sources.

Code of Federal Regulations, 2012 CFR

2012-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.16 Pretreatment standards for new sources. Any...

40 CFR 443.46 - Pretreatment standard for new sources.

Code of Federal Regulations, 2012 CFR

2012-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.46 Pretreatment standard for...

40 CFR 443.46 - Pretreatment standard for new sources.

Code of Federal Regulations, 2014 CFR

2014-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.46 Pretreatment standard for...

40 CFR 443.25 - Standards of performance for new sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.25 Standards of performance for new sources...

40 CFR 443.26 - Pretreatment standard for new sources.

Code of Federal Regulations, 2013 CFR

2013-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.26 Pretreatment standard for new sources. Any...

40 CFR 443.26 - Pretreatment standard for new sources.

Code of Federal Regulations, 2012 CFR

2012-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Concrete Subcategory § 443.26 Pretreatment standard for new sources. Any...

40 CFR 443.16 - Pretreatment standards for new sources.

Code of Federal Regulations, 2014 CFR

2014-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.16 Pretreatment standards for new sources. Any...

40 CFR 443.45 - Standards of performance for new sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.45 Standards of performance...

40 CFR 443.36 - Pretreatment standard for new sources.

Code of Federal Regulations, 2014 CFR

2014-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.36 Pretreatment standard for new sources. Any...

40 CFR 443.15 - Standards of performance for new sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Emulsion Subcategory § 443.15 Standards of performance for new sources...

40 CFR 443.46 - Pretreatment standard for new sources.

Code of Federal Regulations, 2013 CFR

2013-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.46 Pretreatment standard for...

Replacement of Fine Aggregate by using Recyclable Materials in Paving Blocks

NASA Astrophysics Data System (ADS)

Koganti, Shyam Prakash; Hemanthraja, Kommineni; Sajja, Satish

2017-08-01

Cement concrete paving blocks are precast hard products complete out of cement concrete. The product is made in various sizes and shapes like square, round and rectangular blocks of different dimensions with designs for interlocking of adjacent tiles blocks. Several Research Works have been carried out in the past to study the possibility of utilizing waste materials and industrial byproducts in the manufacturing of paver blocks. Various industrial waste materials like quarry dust, glass powder, ceramic dust and coal dust are used as partial replacement of fine aggregate and assessed the strength parameters and compared the profit percentages after replacement with waste materials. Quarry dust can be replaced by 20% and beyond that the difference in strength is not much higher but considering cost we can replace upto 40% so that we can get a profit of almost 10%. Similarly we can replace glass powder and ceramic dust by 20% only beyond that there is decrement in strength and even with 20% replacement we can get 1.34 % and 2.42% of profit. Coal dust is not suitable for alternative material as fine aggregate as it reduces the strength.

40 CFR 52.2054 - Control of asphalt paving material.

Code of Federal Regulations, 2010 CFR

2010-07-01

... work on roadways and shoulders; and (3) No more than 2,500,000 gallons total of emulsion Class E-4 and... additional hydrocarbon emissions from emulsions. (b) The Pennsylvania Department of Transportation is...

40 CFR 52.2054 - Control of asphalt paving material.

Code of Federal Regulations, 2013 CFR

2013-07-01

... work on roadways and shoulders; and (3) No more than 2,500,000 gallons total of emulsion Class E-4 and... additional hydrocarbon emissions from emulsions. (b) The Pennsylvania Department of Transportation is...

40 CFR 52.2054 - Control of asphalt paving material.

Code of Federal Regulations, 2011 CFR

2011-07-01

... work on roadways and shoulders; and (3) No more than 2,500,000 gallons total of emulsion Class E-4 and... additional hydrocarbon emissions from emulsions. (b) The Pennsylvania Department of Transportation is...

40 CFR 52.2054 - Control of asphalt paving material.

Code of Federal Regulations, 2014 CFR

2014-07-01

... work on roadways and shoulders; and (3) No more than 2,500,000 gallons total of emulsion Class E-4 and... additional hydrocarbon emissions from emulsions. (b) The Pennsylvania Department of Transportation is...

40 CFR 52.2054 - Control of asphalt paving material.

Code of Federal Regulations, 2012 CFR

2012-07-01

... work on roadways and shoulders; and (3) No more than 2,500,000 gallons total of emulsion Class E-4 and... additional hydrocarbon emissions from emulsions. (b) The Pennsylvania Department of Transportation is...

40 CFR 443.35 - Standards of performance for new sources.

Code of Federal Regulations, 2011 CFR

2011-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.35 Standards of performance for new sources. The...

40 CFR 443.35 - Standards of performance for new sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.35 Standards of performance for new sources. The...

Evaluation of concrete characteristics for rigid pavements.

DOT National Transportation Integrated Search

1998-04-01

The researcher developed correlations among flexural, split tensile, and compressive strengths and ultrasonic pulse velocity from laboratory testing using materials and mix designs proposed for use in a paving project. These relationships were used t...

Making Sturdy Cloth-Bound Books Using Heat-N-Bond Ultra.

ERIC Educational Resources Information Center

Dwyer, Edward J.; Dwyer, Evelyn

The road to competence in writing is best paved with joyful experiences, especially early experiences with writing in the elementary school. One such experience is writing a story and making a beautiful cloth-bound book. Materials needed, which are easily obtained, are: (1) a commercially produced material called Heat-N-Bond (Ultra); (2) mat board…

Long-term aging of recycled binders.

DOT National Transportation Integrated Search

2015-07-01

Asphalt pavement is Americas most recycled material. Eighty million tons of asphalt, nearly 80% of all milled asphalt pavement, : is recycled every year [1]. To effectively maintain its 40,000 miles of paved roads, the Florida Department of Transp...

Long-term aging of recycled binders : [summary].

DOT National Transportation Integrated Search

2015-10-01

At 80 million tons a year representing more than 80% of all milled asphalt pavement : asphalt paving is Americas most recycled material. Asphalt can be recycled in place, which is : very cost effective; however, aging of recycled binder ca...

Design guide for secondary road pavements in Virginia.

DOT National Transportation Integrated Search

1973-01-01

A design method for secondary roads (based on AASHO Road Test results and experience in Virginia) is described which consists of two parts: the evaluation of the soil support value of the subgrade, the thickness equivalencies of the paving materials,...

Development of quiet and durable porous Portland cement concrete paving materials

DOT National Transportation Integrated Search

2003-09-01

This report outlines the systematic research effort conducted in order to develop and characterize Enhanced Porosity Concrete (EPC) to mitigate the problem of tire-road interaction noise. The basic tenet of this research is that carefully introduced ...

Providing Campus Environmental Coherence by Landscaping.

ERIC Educational Resources Information Center

Pawsey, Maurice R.

1982-01-01

A landscaping approach aimed at integrating greatly contrasting building types and materials resulting from unplanned growth used these elements to create design continuity; paving, planting, landscape furniture, planting and lawn protection, signs, lights, placement of posters and notices, and bicycle racks. (MSE)

Ground tire rubber (GTR) as a component material in concrete mixtures for paving concrete, phase 2 : [summary].

DOT National Transportation Integrated Search

2015-02-01

Using ground tire rubber (GTR) in : concrete mixtures is a possible solution : to mitigating flexibility and thermal : expansion issues with high-strength : concrete pavements. Florida State : University researchers designed concrete : mixtures using...

Radiological Survey and Remediation Report DRMO Yard

DTIC Science & Technology

1996-11-01

remediation, and final release survey over a period beginning August 1995 until the date of this report. The initial survey for radioactive material was...one gage, and 10 hotspots under paved I areas of the east yard (north end) indicating the presence of radioactive material . The dial indicator and...samples at 1.8 g/cc. This is a conservative I error in that the detector will "see" gamma rays with a lower efficiency in the higher density material

Evaluating the use of waste-to-energy bottom ash as road construction materials : [summary].

DOT National Transportation Integrated Search

2014-02-01

Municipal solid waste incineration (MSWI) generates millions of tons of ash each year. In European and Asian countries, this ash has been recycled into road beds, asphalt paving, and concrete products encouraged and enforced by standards, managem...

Laboratory characterization of materials & data management for Ohio-SHRP Projects (U.S. 23).

DOT National Transportation Integrated Search

2002-01-01

About a decade ago, the Federal Highway administration (FHWA) set up a national study called the Long-Term Pavement perfromance (LTTP) under the Stretegic Highway Research program (SHRP) to extend pavement life through investigation of different pave...

Laboratory study of concrete properties to support implementation of the new AASHTO mechanistic-empirical pavement design guide.

DOT National Transportation Integrated Search

2012-09-01

Properties of concrete embodying materials typically used in Wisconsin paving projects were evaluated in support of future : implementation of the AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG). The primary concrete : properties studied w...

Laboratory study of concrete properties to support implementation of the new AASHTO mechanistic empirical pavement design guide.

DOT National Transportation Integrated Search

2012-09-01

Properties of concrete embodying materials typically used in Wisconsin paving projects were evaluated in support of future : implementation of the AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG). The primary concrete : properties studied w...

Learning Rationales and Virtual Reality Technology in Education.

ERIC Educational Resources Information Center

Chiou, Guey-Fa

1995-01-01

Defines and describes virtual reality technology and differentiates between virtual learning environment, learning material, and learning tools. Links learning rationales to virtual reality technology to pave conceptual foundations for application of virtual reality technology education. Constructivism, case-based learning, problem-based learning,…

Ground tire rubber (GTR) as a component material in concrete mixtures for paving concrete.

DOT National Transportation Integrated Search

2015-02-01

This research was done to investigate if the problems associated with flexibility and temperature sensitivity (expansion and : contraction) in roadway concrete pavements can be addressed by replacing some of the fine or coarse aggregate component : w...

Opportunities for conserving energy in asphalt paving processes.

DOT National Transportation Integrated Search

1978-01-01

This report discusses the potential for energy conservation in a number of activities related to the use of asphalt materials in highway construction. It is pointed out that not only should the total energy be considered, but also the category of the...

Recycling of petroleum-contaminated sand.

PubMed

Taha, R; Ba-Omar, M; Pillay, A E; Roos, G; al-Hamdi, A

2001-08-01

The environmental impact of using petroleum-contaminated sand (PCS) as a substitute in asphalt paving mixtures was examined. An appreciable component of PCS is oily sludge, which is found as the dregs in oil storage tanks and is also produced as a result of oil spills on clean sand. The current method for the disposal of oily sludge is land farming. However, this method has not been successful as an oil content of < 1% w/w is required, and difficulty was encountered in reaching this target. The reuse of the sludge in asphalt paving mixtures was therefore considered as an alternative. Standard tests and environmental studies were conducted to establish the integrity of the materials containing the recycled sludge. These included physical and chemical characterization of the sludge itself, and an assessment of the mechanical properties of materials containing 0%, 5%, 22% and 50% oily sludge. The blended mixtures were subjected to special tests, such as Marshall testing and the determination of stability and flow properties. The experimental results indicated that mixtures containing up to 22% oily sludge could meet the necessary criteria for a specific asphalt concrete wearing course or bituminous base course. To maximize the assay from the recycled material, the environmental assessment was restricted to the 50% oily sludge mixture. Leachates associated with this particular mixture were assayed for total organic residue and certain hazardous metal contaminants. The results revealed that the organics were negligible, and the concentrations of the metals were not significant. Thus, no adverse environmental impact should be anticipated from the use of the recycled product. Our research showed that the disposal of oily sludge in asphalt paving mixtures could possibly yield considerable savings per tonne of asphalt concrete, and concurrently minimize any direct impact on the environment.

40 CFR 443.41 - Specialized definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.41 Specialized definitions... from the production of linoleum and printed asphalt felt floor coverings. (c) The term “process...

40 CFR 443.41 - Specialized definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.41 Specialized definitions... from the production of linoleum and printed asphalt felt floor coverings. (c) The term “process...

40 CFR 443.41 - Specialized definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... PERFORMANCE AND PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.41 Specialized definitions... from the production of linoleum and printed asphalt felt floor coverings. (c) The term “process...

Use of manufactured waste shingles in a hot-mix asphalt field project.

DOT National Transportation Integrated Search

2008-01-01

The Virginia Department of Transportation (VDOT) is faced with trying to maintain its roads with materials whose cost is increasing at an alarming rate. The significant cost increase for asphalt concrete, which is used to pave a majority of Virginia'...

[Characteristics of fugitive dust emission from paved road near construction activities].

PubMed

Tian, Gang; Fan, Shou-Bin; Li, Gang; Qin, Jian-Ping

2007-11-01

Because of the mud/dirt carryout from construction activities, the silt loading of paved road nearby is higher and the fugitive dust emission is stronger. By sampling and laboratory analysis of the road surface dust samples, we obtain the silt loading (mass of material equal to or less than 75 micromaters in physical diameter per unit area of travel surface) of paved roads near construction activities. The result show that silt loading of road near construction activities is higher than "normal road", and silt loading is negatively correlated with length from construction's door. According to AP-42 emission factor model of fugitive dust from roads, the emission factor of influenced road is 2 - 10 times bigger than "normal road", and the amount of fugitive dust emission influenced by one construction activity is "equivalent" to an additional road length of approximately 422 - 3 800 m with the baseline silt loading. Based on the spatial and temporal distribution of construction activities, in 2002 the amount of PM10 emission influenced by construction activities in Beijing city areas account of for 59% of fugitive dust from roads.

40 CFR 443.31 - Specialized definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.31 Specialized definitions. For the purpose of this subpart: (a..., intermediate product, by-product, or product used in or resulting from the production of asphalt roofing...

40 CFR 443.41 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.41 Specialized definitions. For the purpose of... linoleum and printed asphalt felt floor coverings. (c) The term “process wastewater pollutants” shall mean...

40 CFR 443.31 - Specialized definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Asphalt Roofing Subcategory § 443.31 Specialized definitions. For the purpose of this subpart: (a..., intermediate product, by-product, or product used in or resulting from the production of asphalt roofing...

40 CFR 443.41 - Specialized definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... PRETREATMENT STANDARDS FOR NEW SOURCES FOR THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.41 Specialized definitions. For the purpose of... linoleum and printed asphalt felt floor coverings. (c) The term “process wastewater pollutants” shall mean...

Construction, testing and performance report : state study no. 137 : resin modified pavement demonstration project.

DOT National Transportation Integrated Search

2007-09-01

Resin Modified Pavement (RMP) is a composite paving material consisting of a thin layer (2 inches) : of open graded hot mix asphalt (HMA) whose internal air voids (approximately 30% voids) are : filled with a latex rubber-modified portland cement gro...

Characterization and development of truck load spectra and growth factors for current and future pavement design practices in Louisiana.

DOT National Transportation Integrated Search

2011-07-01

For pavement design practices, several factors must be considered to ensure good pavement performance over the anticipated life cycle. : Such factors include, but are not limited to, the type of paving materials, traffic loading characteristics, prev...

ASPHALT FOR OFF-STREET PAVING AND PLAY AREAS, 3RD EDITION.

ERIC Educational Resources Information Center

Asphalt Inst., College Park, MD.

THIS PAMPHLET DISCUSSES THE ALTERNATIVE METHODS, APPLICATIONS, AND TECHNICAL CONSIDERATIONS FOR OFF-STREET PAVING AND PLAY AREAS. OFF-STREET PAVING INCLUDES--(1) ASPHALT-PAVED PARKING AREAS, (2) ROOF DECK PARKING AREAS, (3) ASPHALT-PAVED DRIVEWAYS, (4) ASPHALT-PAVED SERVICE STATION LOTS, AND (5) SIDEWALKS. THE DISCUSSION OF PLAY AREAS…

40 CFR 443.40 - Applicability; description of the linoleum and printed asphalt felt subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... linoleum and printed asphalt felt subcategory. 443.40 Section 443.40 Protection of Environment... PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.40 Applicability; description of the linoleum and printed asphalt felt subcategory. The...

40 CFR 443.40 - Applicability; description of the linoleum and printed asphalt felt subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... linoleum and printed asphalt felt subcategory. 443.40 Section 443.40 Protection of Environment... THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.40 Applicability; description of the linoleum and printed asphalt felt...

40 CFR 443.40 - Applicability; description of the linoleum and printed asphalt felt subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... linoleum and printed asphalt felt subcategory. 443.40 Section 443.40 Protection of Environment... THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.40 Applicability; description of the linoleum and printed asphalt felt...

40 CFR 443.40 - Applicability; description of the linoleum and printed asphalt felt subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... linoleum and printed asphalt felt subcategory. 443.40 Section 443.40 Protection of Environment... PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.40 Applicability; description of the linoleum and printed asphalt felt subcategory. The...

40 CFR 443.40 - Applicability; description of the linoleum and printed asphalt felt subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... linoleum and printed asphalt felt subcategory. 443.40 Section 443.40 Protection of Environment... THE PAVING AND ROOFING MATERIALS (TARS AND ASPHALT) POINT SOURCE CATEGORY Linoleum and Printed Asphalt Felt Subcategory § 443.40 Applicability; description of the linoleum and printed asphalt felt...

Design method for secondary road flexible pavements in Virginia : also suggested for subdivision and other road systems.

DOT National Transportation Integrated Search

1972-01-01

The design method for secondary roads is based on AASHO Road Test Results and Virginia's design experience. It is divided into two parts. (1) the evaluation of the soil support value of the subgrade, the thickness equivalencies of the paving material...

Dimpled elastic sheets: a new class of non-porous negative Poisson’s ratio materials

NASA Astrophysics Data System (ADS)

Javid, Farhad; Smith-Roberge, Evelyne; Innes, Matthew C.; Shanian, Ali; Weaver, James C.; Bertoldi, Katia

2015-12-01

In this study, we report a novel periodic material with negative Poisson’s ratio (also called auxetic materials) fabricated by denting spherical dimples in an elastic flat sheet. While previously reported auxetic materials are either porous or comprise at least two phases, the material proposed here is non-porous and made of a homogeneous elastic sheet. Importantly, the auxetic behavior is induced by a novel mechanism which exploits the out-of-plane deformation of the spherical dimples. Through a combination of experiments and numerical analyses, we demonstrate the robustness of the proposed concept, paving the way for developing a new class of auxetic materials that significantly expand their design space and possible applications.

77 FR 14691 - Approval and Promulgation of Air Quality Implementation Plans; Rhode Island; Reasonably Available...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-13

.... Specifically, the requirement does not apply to cold cleaning machines: (1) Used in ``special and extreme... products; 2. Requirements for charcoal lighter materials, aerosol adhesives and floor wax strippers; 3...). This APC regulation applies to anyone that solicits the use of or applies asphalt for road paving...

Development of laboratory testing facility for evaluation of base-soil behavior under repeated loading : phase 1 : feasibility study.

DOT National Transportation Integrated Search

2005-02-01

Accelerated load testing of paved and unpaved roads is the application of a large number of load repetitions in a short period of time. This type of testing is an economic way to determine the behavior of roads and compare different materials, struct...

76 FR 37393 - FY 2011 Discretionary Livability Funding Opportunity; Section 5309 Bus and Bus Facilities...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-27

... heating, solar panels, wind turbines, reflective roofing or paving materials, or other advanced... notification, FTA's system will notify the applicant if there are any problems with the submitted Supplemental... receive the validation message and to correct any problems that may have caused the application to be...

A Curriculum Guide for Achieving Equity in Education and the Workplace.

ERIC Educational Resources Information Center

Vocational Curriculum Resource Center of Maine, Fairfield.

This curriculum guide provides instructional materials that offer suggestions and strategies to change mindsets and remove barriers in order to pave the way for a gender-equitable, technically trained work force. A DACUM (Developing a Curriculum) chart forms the basis for the task performance guides provided for five audiences: students,…

Study on mechanical and physical properties of composite materials with recycled PET as fillers for paving block application

NASA Astrophysics Data System (ADS)

Wicaksono, Sigit Tri; Ardhyananta, Hosta; Rasyida, Amaliya

2018-04-01

Base on Sidoarjo's goverment data, there was more than 4000 metric ton perday of waste that has been accumulated during 2016. More than 10 percent from overall waste is plastics. In accordance with the Indonesia government regulation, "Indonesia clean from waste" by 2020 through 3R (Reduce, Reuse and Recycle) program, we have been focusing research on how to reduce the accumulation of the plastics waste in Sidoarjo by processing it become a new product. In this research, we have made the plastic waste of PET bottle as additional fillers or agregates of composite material for construction application as a paving block. The composition of PET plastic used as fillers is vary from 0, 10, 20, 30, 40 and 50% from total volume of agregates. The ratio of cement binder to sands agregate is 1:3. The specimens were characterized its mechanical and physical properties by using flexural testing, compressive testing, density and water absorbance measurement. The results show that the mechanical (flexural and compressive) properties of composite materials is increased significantly by increasing PET fillers up to 20%, however it was decreased when PET content more than 20%. But, both the density and water absobance of specimens are decreased by increasing of PET fillers.

A review of changes in composition of hot mix asphalt in the United States.

PubMed

Mundt, Diane J; Marano, Kristin M; Nunes, Anthony P; Adams, Robert C

2009-11-01

This review researched the materials, methods, and practices in the hot mix asphalt industry that might impact future exposure assessments and epidemiologic research on road paving workers. Since World War II, the U.S. interstate highway system, increased traffic volume, transportation speeds, and vehicle axle loads have necessitated an increase in demand for hot mix asphalt for road construction and maintenance, while requiring a consistent road paving product that meets state-specific physical performance specifications. We reviewed typical practices in hot mix asphalt paving in the United States to understand the extent to which materials are and have been added to hot mix asphalt to meet specifications and how changes in practices and technology could affect evaluation of worker exposures for future research. Historical documents were reviewed, and industry experts from 16 states were interviewed to obtain relevant information on industry practices. Participants from all states reported additive use, with most being less than 2% by weight. Crumb rubber and recycled asphalt pavement were added in concentrations approximately 10% per unit weight of the mix. The most frequently added materials included polymers and anti-stripping agents. Crumb rubber, sulfur, asbestos, roofing shingles, slag, or fly ash have been used in limited amounts for short periods of time or in limited geographic areas. No state reported using coal tar as an additive to hot mix asphalt or as a binder alternative in hot mix pavements for high-volume road construction. Coal tar may be present in recycled asphalt pavement from historical use, which would need to be considered in future exposure assessments of pavers. Changes in hot mix asphalt production and laydown emission control equipment have been universally implemented over time as the technology has become available to reduce potential worker exposures. This work is a companion review to a study undertaken in the petroleum refining sector that investigated current and historical use of additives in producing petroleum-derived asphalt cements.

Gamma motes for detection of radioactive materials in shipping containers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harold McHugh; William Quam; Stephan Weeks

Shipping containers can be effectively monitored for radiological materials using gamma (and neutron) motes in distributed mesh networks. The mote platform is ideal for collecting data for integration into operational management systems required for efficiently and transparently monitoring international trade. Significant reductions in size and power requirements have been achieved for room-temperature cadmium zinc telluride (CZT) gamma detectors. Miniaturization of radio modules and microcontroller units are paving the way for low-power, deeply-embedded, wireless sensor distributed mesh networks.

Compact Layers of Hybrid Halide Perovskites Fabricated via the Aerosol Deposition Process-Uncoupling Material Synthesis and Layer Formation.

PubMed

Panzer, Fabian; Hanft, Dominik; Gujar, Tanaji P; Kahle, Frank-Julian; Thelakkat, Mukundan; Köhler, Anna; Moos, Ralf

2016-04-08

We present the successful fabrication of CH₃NH₃PbI₃ perovskite layers by the aerosol deposition method (ADM). The layers show high structural purity and compactness, thus making them suitable for application in perovskite-based optoelectronic devices. By using the aerosol deposition method we are able to decouple material synthesis from layer processing. Our results therefore allow for enhanced and easy control over the fabrication of perovskite-based devices, further paving the way for their commercialization.

Nexus networks in carbon honeycombs

NASA Astrophysics Data System (ADS)

Chen, Yuanping; Xie, Yuee; Gao, Yan; Chang, Po-Yao; Zhang, Shengbai; Vanderbilt, David

2018-04-01

Nexus metals represent a new type of topological material in which nodal lines merge at nexus points. Here we propose novel networks in nexus systems through intertwining between nexus fermions and additional nodal lines. These nexus networks can be realized in recently synthesized carbon honeycomb materials. In these carbon honeycombs, we demonstrate a phase transition between a nexus network and a system with triply degenerate points and additional nodal lines. The Landau level spectra show unusual magnetic transport properties in the nexus networks. Our results pave the way toward realizations of new topological materials with novel transport properties beyond standard Weyl/Dirac semimetals.

Tunable Bragg filters with a phase transition material defect layer

DOE PAGES

Wang, Xi; Gong, Zilun; Dong, Kaichen; ...

2016-01-01

We propose an all-solid-state tunable Bragg filter with a phase transition material as the defect layer. Bragg filters based on a vanadium dioxide defect layer sandwiched between silicon dioxide/titanium dioxide Bragg gratings are experimentally demonstrated. Temperature dependent reflection spectroscopy shows the dynamic tunability and hysteresis properties of the Bragg filter. Temperature dependent Raman spectroscopy reveals the connection between the tunability and the phase transition of the vanadium dioxide defect layer. This work paves a new avenue in tunable Bragg filter designs and promises more applications by combining phase transition materials and optical cavities.

Tunable Bragg filters with a phase transition material defect layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xi; Gong, Zilun; Dong, Kaichen

We propose an all-solid-state tunable Bragg filter with a phase transition material as the defect layer. Bragg filters based on a vanadium dioxide defect layer sandwiched between silicon dioxide/titanium dioxide Bragg gratings are experimentally demonstrated. Temperature dependent reflection spectroscopy shows the dynamic tunability and hysteresis properties of the Bragg filter. Temperature dependent Raman spectroscopy reveals the connection between the tunability and the phase transition of the vanadium dioxide defect layer. This work paves a new avenue in tunable Bragg filter designs and promises more applications by combining phase transition materials and optical cavities.

Statewide implementation of Pave-IR in the Texas Department of Transportation.

DOT National Transportation Integrated Search

2012-02-01

This project conducted work to complement implementation of Pave-IR into the Texas Department of : Transportations hot-mix-asphalt quality control/quality assurance specification. Pave-IR provides real-time : thermal profiling of paving operations...

Understanding pave-IR : background, use, and advanced techniques

DOT National Transportation Integrated Search

2010-01-01

Why Has TxDOT Implemented Pave-IR? : Promote more uniform, higher quality pavements : Minimize/eliminate thermal segregation : Expand range of weather conditions for paving : Special Provision 341-024 : Contains option for contractor to use Pave-IR :...

Review of paved shoulders.

DOT National Transportation Integrated Search

1990-01-01

The objectives of this study were (1) to review the literature on paved shoulders, (2) to survey state departments of transportation on their use of paved shoulders on two laneroads, (3) to perform a cost analysis on paved shoulders, and (4) to draw ...

Brick Paving Systems in Expeditionary Environments: Field Testing

DTIC Science & Technology

2012-07-01

specific gravity of 2.7, optimum moisture content of 2.6 percent, and a maximum dry density of 114.2 pcf. Figure 5 shows the Proctor curve developed by...4  Figure 3. Dry density versus moisture content for CH material...6  Figure 5. Dry density versus moisture content for blended GM base course. ..................................... 7  Figure 6

76 FR 4298 - Certain New Pneumatic Off-the-Road Tires From the People's Republic of China: Notice of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-25

... grading'' in road construction. \\16\\ A straddle carrier is a rigid frame, engine-powered machine that is... road construction to prepare the base course onto which asphalt or other paving material will be laid...-the-Road Tires From the People's Republic of China: Notice of Rescission of Changed Circumstances...

Project Magnify: Increasing Reading Skills in Students with Low Vision

ERIC Educational Resources Information Center

Farmer, Jeanie; Morse, Stephen E.

2007-01-01

Modeled after Project PAVE (Corn et al., 2003) in Tennessee, Project Magnify is designed to test the idea that students with low vision who use individually prescribed magnification devices for reading will perform as well as or better than students with low vision who use large-print reading materials. Sixteen students with low vision were…

Effect of Temperature and Process on Quantity and Composition of Laboratory-generated Bitumen Emissions.

PubMed

Bolliet, Christophe; Kriech, Anthony J; Juery, Catherine; Vaissiere, Mathieu; Brinton, Michael A; Osborn, Linda V

2015-01-01

In this study we investigated the impact of temperature on emissions as related to various bitumen applications and processes used in commercial products. Bitumen emissions are very complex and can be influenced in quantity and composition by differences in crude source, refining processes, application temperature, and work practices. This study provided a controlled laboratory environment to study five bitumen test materials from three European refineries; three paving grade, one used for primarily roofing and some paving applications, and one oxidized industrial specialty bitumen. Emissions were generated at temperatures between 140°C and 230°C based on typical application temperatures of each product. Emissions were characterized by aerodynamic particle size, total organic matter (TOM), simulated distillation, 40 individual PACs, and fluorescence (FL-PACs) spectroscopy. Results showed that composition of bitumen emissions is influenced by temperature under studied experimental conditions. A distinction between the oxidized bitumen with flux oil (industrial specialty bitumen) and the remaining bitumens was observed. Under typical temperatures used for paving (150°C-170°C), the TOM and PAC concentrations in the emissions were low. However, bitumen with flux oil produced significantly higher emissions at 230°C, laden with high levels of PACs. Flux oil in this bitumen mixture enhanced release of higher boiling-ranged compounds during application conditions. At 200°C and below, concentrations of 4-6 ring PACs were ≤6.51 μg/m(3) for all test materials, even when flux oil was used. Trends learned about emission temperature-process relationships from this study can be used to guide industry decisions to reduce worker exposure during processing and application of hot bitumen.

Pave-IR operator's manual version 1.3 : a thermal imaging system for evaluating hot-mix asphalt paving operations.

DOT National Transportation Integrated Search

2009-06-01

This product updates the prior users manual for Pave-IR to reflect changes in hardware and software made : to accommodate collection of GPS data simultaneously during the collection of thermal profiles. The current : Pave-IR system described in th...

Primary reflector for solar energy collection systems

NASA Technical Reports Server (NTRS)

Miller, C. G. (Inventor); Stephens, J. B.

1978-01-01

A fixed, linear, ground-based primary reflector is disclosed which has an extended curved sawtooth-contoured surface covered with a metalized polymeric reflecting material. The device reflects solar energy to a movably supported collector that is kept at the concentrated line focus of the reflector primary. The primary reflector may be constructed by a process utilizing well-known freeway paving machinery.

Primary reflector for solar energy collection systems and method of making same

NASA Technical Reports Server (NTRS)

Miller, C. G.; Stephens, J. B. (Inventor)

1979-01-01

Solar energy is reflected to a movably supported collector that is kept at the concentrated line focus of the reflector primary by a fixed, linear, ground-based primary reflector having an extended curved sawtooth contoured surface covered with a metalized polymeric reflecting material. The primary reflector was constructed by a process utilizing well-known freeway paving machinery.

Nanostructured materials with plasmonic nanobiosensors for early cancer detection: A past and future prospect.

PubMed

Sugumaran, Sathish; Jamlos, Mohd Faizal; Ahmad, Mohd Noor; Bellan, Chandar Shekar; Schreurs, Dominique

2018-02-15

Early cancer detection and treatment is an emerging and fascinating field of plasmonic nanobiosensor research. It paves to enrich a life without affecting living cells leading to a possible survival of the patient. This review describes a past and future prospect of an integrated research field on nanostructured metamaterials, microwave transmission, surface plasmonic resonance, nanoantennas, and their manifested versatile properties with nano-biosensors towards early cancer detection to preserve human health. Interestingly, (i) microwave transmission shows more advantages than other electromagnetic radiation in reacting with biological tissues, (ii) nanostructured metamaterial (Au) with special properties like size and shape can stimulate plasmonic effects, (iii) plasmonic based nanobiosensors are to explore the efficacy for early cancer tumour detection or single molecular detection and (iv) nanoantenna wireless communication by using microwave inverse scattering nanomesh (MISN) technique instead of conventional techniques can be adopted to characterize the microwave scattered signals from the biomarkers. It reveals that the nanostructured material with plasmonic nanobiosensor paves a fascinating platform towards early detection of cancer tumour and is anticipated to be exploited as a magnificent field in the future. Copyright © 2017 Elsevier B.V. All rights reserved.

Concrete Block Pavements

DTIC Science & Technology

1983-03-01

concrete paving block ( Van der Vlist 1980). The concrete paving block was readily accepted as a substitute for the scarce paving brick and today has...seen in Figure 4, its growth.has been steady ( Van der Vlist 1980). 20 15 0< 0. n 10 1𔃺 978 960 1 62 63 64 65 66 67 68 6970 71 72 73 74 7678 7778 79...Figure 4. Concrete paving block production in the Netherlands ( Van der Vlist 1980) 8. The use of concrete paving block in the Netherlands developedI

High-κ/Metal Gate Science and Technology

NASA Astrophysics Data System (ADS)

Guha, Supratik; Narayanan, Vijay

2009-08-01

High-κ/metal gate technology is on the verge of replacing conventional oxynitride dielectrics in state-of-the-art transistors for both high-performance and low-power applications. In this review we discuss some of the key materials issues that complicated the introduction of high-κ dielectrics, including reduced electron mobility, oxygen-based thermal instabilities, and the absence of thermally stable dual-metal electrodes. We show that through a combination of materials innovations and engineering ingenuity these issues were successfully overcome, thereby paving the way for high-κ/metal gate implementation.

14 CFR 151.79 - Runway paving: Second runway; wind conditions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Runway paving: Second runway; wind...: Second runway; wind conditions. (a) All airports. Paving a second runway on the basis of wind conditions... second runway is oriented with the existing paved runway to achieve the maximum wind coverage, with due...

14 CFR 151.79 - Runway paving: Second runway; wind conditions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Runway paving: Second runway; wind...: Second runway; wind conditions. (a) All airports. Paving a second runway on the basis of wind conditions... second runway is oriented with the existing paved runway to achieve the maximum wind coverage, with due...

14 CFR 151.79 - Runway paving: Second runway; wind conditions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Runway paving: Second runway; wind...: Second runway; wind conditions. (a) All airports. Paving a second runway on the basis of wind conditions... second runway is oriented with the existing paved runway to achieve the maximum wind coverage, with due...

14 CFR 151.79 - Runway paving: Second runway; wind conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Runway paving: Second runway; wind...: Second runway; wind conditions. (a) All airports. Paving a second runway on the basis of wind conditions... second runway is oriented with the existing paved runway to achieve the maximum wind coverage, with due...

Bonding Directionality Matters: Direct-Indirect Transition in Few-Layer SnSe

NASA Astrophysics Data System (ADS)

Sirikumara, Hansika; Jayasekera, Thushari

SnSe is one of the best thermoelectric materials reported to date. The possibility of growing few-layer SnSe helped boost the interest in SnSe, and paves the path for various other applications such as photovoltaics and optoelectronics. However, indirect band gap of SnSe hinders its success in such fields. Based on the results from first principles Density Functional Theory, we carefully analyzed electronic band structures of bulk, mono and few-layer SnSe with various interlayer stackings. Our results reveal that it is the directionality of interlayer interactions, which leads to the indirect electronic band gap. In fact, by modifying the interface between layers, there is a possibility of achieving few-layer SnSe with direct electronic band gap. Moreover, the fundamental understanding of interlayer interactions at the atomic level also paves the path for designing Van der Waals heterostructures based on SnSe with prescribed electronic properties.

Super-resolution nanofabrication with metal-ion doped hybrid material through an optical dual-beam approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Yaoyu; Li, Xiangping; Gu, Min, E-mail: mgu@swin.edu.au

2014-12-29

We apply an optical dual-beam approach to a metal-ion doped hybrid material to achieve nanofeatures beyond the optical diffraction limit. By spatially inhibiting the photoreduction and the photopolymerization, we realize a nano-line, consisting of polymer matrix and in-situ generated gold nanoparticles, with a lateral size of sub 100 nm, corresponding to a factor of 7 improvement compared to the diffraction limit. With the existence of gold nanoparticles, a plasmon enhanced super-resolution fabrication mechanism in the hybrid material is observed, which benefits in a further reduction in size of the fabricated feature. The demonstrated nanofeature in hybrid materials paves the way formore » realizing functional nanostructures.« less

Introducing Magneto-Optical Functions into Soft Materials

DTIC Science & Technology

2017-05-03

the electromagnet as illustrated in Figure 1(b). This experimental measurement allowed us to explore magneto- electric coupling in both ground and...short-range spin-spin interaction. As a general conclusion, the -d electron coupling promise the existence of photo-adjustable magneto- electric ...coupling, paving the way for the realization of magneto- electric -optical applications. Intermoleuar SOC SB Orb S B OrbHinter Hinter 1 2 (b

Latin America Report

DTIC Science & Technology

1986-11-25

Cancun in Mexico, The oil deal is part of the arrangement under which Petrojam is to lease the Libertad sugar factory at Corazon, Belize, to produce...government leaders and businessmen from the tourist sector also attended the luncheon. The paving and expansion of the landing strip in the...editorial reports, and material enclosed in brackets [] are supplied by JPRS. Processing indicators such as [Text] or [Excerpt] in the first line

Enabling Dissimilar Material Joining Using Friction Stir Scribe Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hovanski, Yuri; Upadyay, Piyush; Kleinbaum, Sarah

2017-04-05

One challenge in adapting welding processes to dissimilar material joining is the diversity of melting temperatures of the different materials. Although the use of mechanical fasteners and adhesives have mostly paved the way for near-term implementation of dissimilar material systems, these processes only accentuate the need for low-cost welding processes capable of joining dissimilar material components regardless of alloy, properties, or melting temperature. Friction stir scribe technology was developed to overcome the challenges of joining dissimilar material components where melting temperatures vary greatly, and properties and/or chemistry are not compatible with more traditional welding processes. Although the friction stir scribemore » process is capable of joining dissimilar metals and metal/polymer systems, a more detailed evaluation of several aluminum/steel joints is presented herein to demonstrate the ability to both chemically and mechanically join dissimilar materials.« less

Enabling Dissimilar Material Joining Using Friction Stir Scribe Technology

DOE PAGES

Hovanski, Yuri; Upadyay, Piyush; Kleinbaum, Sarah; ...

2017-04-05

One challenge in adapting welding processes to dissimilar material joining is the diversity of melting temperatures of the different materials. Although the use of mechanical fasteners and adhesives have mostly paved the way for near-term implementation of dissimilar material systems, these processes only accentuate the need for low-cost welding processes capable of impartially joining dissimilar material components regardless of alloy, properties, or melting temperature. Friction stir scribe technology was developed to overcome the challenges of joining dissimilar material components where melting temperatures vary greatly, and properties and/or chemistry are not compatible with more traditional welding processes. Finally, although the frictionmore » stir scribe process is capable of joining dissimilar metals and metal/polymer systems, a more detailed evaluation of several aluminum/steel joints is presented herein to demonstrate the ability to both chemically and mechanically join dissimilar materials.« less

Los Alamos Using Neutrons to Stop Nuclear Smugglers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Favalli, Andrea; Swinhoe, Martyn; Roark, Kevin

Los Alamos National Laboratory researchers have successfully demonstrated for the first time that laser-generated neutrons can be enlisted as a useful tool in the War on Terror. The international research team used the short-pulse laser at Los Alamos's TRIDENT facility to generate a neutron beam with novel characteristics that interrogated a closed container to confirm the presence and quantity of nuclear material inside. The successful experiment paves the way for creation of a table-top-sized or truck-mounted neutron generator that could be installed at strategic locations worldwide to thwart smugglers trafficking in nuclear materials.

Los Alamos Using Neutrons to Stop Nuclear Smugglers

ScienceCinema

Favalli, Andrea; Swinhoe, Martyn; Roark, Kevin

2018-02-14

Los Alamos National Laboratory researchers have successfully demonstrated for the first time that laser-generated neutrons can be enlisted as a useful tool in the War on Terror. The international research team used the short-pulse laser at Los Alamos's TRIDENT facility to generate a neutron beam with novel characteristics that interrogated a closed container to confirm the presence and quantity of nuclear material inside. The successful experiment paves the way for creation of a table-top-sized or truck-mounted neutron generator that could be installed at strategic locations worldwide to thwart smugglers trafficking in nuclear materials.

Monolithic 3D CMOS Using Layered Semiconductors.

PubMed

Sachid, Angada B; Tosun, Mahmut; Desai, Sujay B; Hsu, Ching-Yi; Lien, Der-Hsien; Madhvapathy, Surabhi R; Chen, Yu-Ze; Hettick, Mark; Kang, Jeong Seuk; Zeng, Yuping; He, Jr-Hau; Chang, Edward Yi; Chueh, Yu-Lun; Javey, Ali; Hu, Chenming

2016-04-06

Monolithic 3D integrated circuits using transition metal dichalcogenide materials and low-temperature processing are reported. A variety of digital and analog circuits are implemented on two sequentially integrated layers of devices. Inverter circuit operation at an ultralow supply voltage of 150 mV is achieved, paving the way to high-density, ultralow-voltage, and ultralow-power applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Engineering Properties of Resin Modified Pavement (RMP) for Mechanistic Design

DTIC Science & Technology

2000-03-01

conducted by personnel of the Airfields and Pavements Division (APD), Geotechnical Laboratory (GL), ERDC, Vicksburg, MS, during the period October 1995...mixture and resin modified portland cement grout are produced and placed separately . The RMP is typically a 50-mm-thick layer placed on top of a...military installations in the following years. The Federal Aviation Administration, also eager to develop an alternative paving material technology

Heat Shield Paves the Way for Commercial Space

NASA Technical Reports Server (NTRS)

2014-01-01

The Phenolic-Impregnated Carbon Ablator (PICA) heat shield, a lightweight material designed to withstand high temperatures, was used for the Stardust’s reentry into Earth’s atmosphere. Hawthorne, California-based SpaceX later worked with the inventors at Ames Research Center to outfit PICA on its Dragon capsule, which is now delivering cargo to and from the International Space Station through NASA’s Commercial Resupply Services contracts program.

The Papillomavirus Episteme: a central resource for papillomavirus sequence data and analysis.

PubMed

Van Doorslaer, Koenraad; Tan, Qina; Xirasagar, Sandhya; Bandaru, Sandya; Gopalan, Vivek; Mohamoud, Yasmin; Huyen, Yentram; McBride, Alison A

2013-01-01

The goal of the Papillomavirus Episteme (PaVE) is to provide an integrated resource for the analysis of papillomavirus (PV) genome sequences and related information. The PaVE is a freely accessible, web-based tool (http://pave.niaid.nih.gov) created around a relational database, which enables storage, analysis and exchange of sequence information. From a design perspective, the PaVE adopts an Open Source software approach and stresses the integration and reuse of existing tools. Reference PV genome sequences have been extracted from publicly available databases and reannotated using a custom-created tool. To date, the PaVE contains 241 annotated PV genomes, 2245 genes and regions, 2004 protein sequences and 47 protein structures, which users can explore, analyze or download. The PaVE provides scientists with the data and tools needed to accelerate scientific progress for the study and treatment of diseases caused by PVs.

Portland cement hydration and early setting of cement stone intended for efficient paving materials

NASA Astrophysics Data System (ADS)

Grishina, A.

2017-10-01

Due to the growth of load on automotive roads, modern transportation engineering is in need of efficient paving materials. Runways and most advanced highways require Portland cement concretes. This makes important the studies directed to improvement of binders for such concretes. In the present work some peculiarities of the process of Portland cement hydration and early setting of cement stone with barium hydrosilicate sol were examined. It was found that the admixture of said sol leads to a shift in the induction period to later times without significant change in its duration. The admixture of a modifier with nanoscale barium hydrosilicates increases the degree of hydration of the cement clinker minerals and changes the phase composition of the hydration products; in particular, the content of portlandite and tricalcium silicate decreases, while the amount of ettringite increases. Changes in the hydration processes of Portland cement and early setting of cement stone that are caused by the nanoscale barium hydrosilicates, allow to forecast positive technological effects both at the stage of manufacturing and at the stage of operation. In particular, the formwork age can be reduced, turnover of molds can be increased, formation of secondary ettringite and corrosion of the first type can be eliminated.

Design and experimental verification of a water-like pentamode material

NASA Astrophysics Data System (ADS)

Zhao, Aiguo; Zhao, Zhigao; Zhang, Xiangdong; Cai, Xuan; Wang, Lei; Wu, Tao; Chen, Hong

2017-01-01

Pentamode materials approximate tailorable artificial liquids. Recently, microscopic versions of these intricate structures have been fabricated, and the static mechanical experiments reveal that the ratio of bulk modulus to shear modulus as large as 1000 can be obtained. However, no direct acoustic experimental characterizations have been reported yet. In this paper, a water-like two-dimensional pentamode material sample is designed and fabricated with a single metallic material, which is a hollow metallic foam-like structure at centimeter scale. Acoustic simulation and experimental testing results indicate that the designed pentamode material mimics water in acoustic properties over a wide frequency range, i.e., it exhibits transparency when surrounded by water. This work contributes to the development of microstructural design of materials with specific modulus and density distribution, thus paving the way for the physical realization of special acoustic devices such as metamaterial lenses and vibration isolation.

Power Electronic Semiconductor Materials for Automotive and Energy Saving Applications - SiC, GaN, Ga2O3, and Diamond.

PubMed

Wellmann, Peter J

2017-11-17

Power electronics belongs to the future key technologies in order to increase system efficiency as well as performance in automotive and energy saving applications. Silicon is the major material for electronic switches since decades. Advanced fabrication processes and sophisticated electronic device designs have optimized the silicon electronic device performance almost to their theoretical limit. Therefore, to increase the system performance, new materials that exhibit physical and chemical properties beyond silicon need to be explored. A number of wide bandgap semiconductors like silicon carbide, gallium nitride, gallium oxide, and diamond exhibit outstanding characteristics that may pave the way to new performance levels. The review will introduce these materials by (i) highlighting their properties, (ii) introducing the challenges in materials growth, and (iii) outlining limits that need innovation steps in materials processing to outperform current technologies.

Power Electronic Semiconductor Materials for Automotive and Energy Saving Applications – SiC, GaN, Ga2O3, and Diamond

PubMed Central

2017-01-01

Power electronics belongs to the future key technologies in order to increase system efficiency as well as performance in automotive and energy saving applications. Silicon is the major material for electronic switches since decades. Advanced fabrication processes and sophisticated electronic device designs have optimized the silicon electronic device performance almost to their theoretical limit. Therefore, to increase the system performance, new materials that exhibit physical and chemical properties beyond silicon need to be explored. A number of wide bandgap semiconductors like silicon carbide, gallium nitride, gallium oxide, and diamond exhibit outstanding characteristics that may pave the way to new performance levels. The review will introduce these materials by (i) highlighting their properties, (ii) introducing the challenges in materials growth, and (iii) outlining limits that need innovation steps in materials processing to outperform current technologies. PMID:29200530

Performance of TenCate Paving interlayers in asphalt concrete pavements.

DOT National Transportation Integrated Search

2017-08-01

As a continued effort of a previously completed project entitled Performance of TenCate Mirafi PGM-G4 Interlayer-Reinforced Asphalt Pavements in Alaska, this project evaluated two newly modified paving interlayers (TruPave and Mirapave) through...

An asphalt paving tool for adverse conditions

DOT National Transportation Integrated Search

1998-06-01

Poor compaction can lead to early deterioration of an asphalt pavement. It often happens when paving occurs during adverse weather conditions. Yet, in Minnesota, paving must often occur under adverse conditions. A new tool now simulates the cooling o...

To pave or not to pave?

DOT National Transportation Integrated Search

2006-10-01

The Issue : Two key questions must be answered when developing a gravel : road maintenance plan: : 1. What is the best way to maintain a gravel road? : 2. When should the roadway be upgraded to a paved surface? : These are not easy questions because ...

Excess Foundry Sand Characterization and Experimental Investigation in Controlled Low-Strength Material and Hot-Mixing Asphalt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tikalsky, Paul J.; Bahia, Hussain U.; Deng, An

2004-10-15

This report provides technical data regarding the reuse of excess foundry sand. The report addresses three topics: a statistically sound evaluation of the characterization of foundry sand, a laboratory investigation to qualify excess foundry sand as a major component in controlled low-strength material (CLSM), and the identification of the best methods for using foundry sand as a replacement for natural aggregates for construction purposes, specifically in asphalt paving materials. The survival analysis statistical technique was used to characterize foundry sand over a full spectrum of general chemical parameters, metallic elements, and organic compounds regarding bulk analysis and leachate characterization. Notmore » limited to characterization and environmental impact, foundry sand was evaluated by factor analyses, which contributes to proper selection of factor and maximization of the reuse marketplace for foundry sand. Regarding the integration of foundry sand into CLSM, excavatable CLSM and structural CLSM containing different types of excess foundry sands were investigated through laboratory experiments. Foundry sand was approved to constitute a major component in CLSM. Regarding the integration of foundry sand into asphalt paving materials, the optimum asphalt content was determined for each mixture, as well as the bulk density, maximum density, asphalt absorption, and air voids at Nini, Ndes, and Nmax. It was found that foundry sands can be used as an aggregate in hot-mix asphalt production, but each sand should be evaluated individually. Foundry sands tend to lower the strength of mixtures and also may make them more susceptible to moisture damage. Finally, traditional anti-stripping additives may decrease the moisture sensitivity of a mixture containing foundry sand, but not to the level allowed by most highway agencies.« less

Excess Foundry Sand Characterization and Experimental Investigation in Controlled Low-Strength Material and Hot-Mixing Asphalt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pauul J. Tikalsky

2004-10-31

This report provides technical data regarding the reuse of excess foundry sand. The report addresses three topics: (1) a statistically sound evaluation of the characterization of foundry sand, (2) a laboratory investigation to qualify excess foundry sand as a major component in controlled low-strength material (CLSM), and (3) the identification of the best methods for using foundry sand as a replacement for natural aggregates for construction purposes, specifically in asphalt paving materials. The survival analysis statistical technique was used to characterize foundry sand over a full spectrum of general chemical parameters, metallic elements, and organic compounds regarding bulk analysis andmore » leachate characterization. Not limited to characterization and environmental impact, foundry sand was evaluated by factor analyses, which contributes to proper selection of factor and maximization of the reuse marketplace for foundry sand. Regarding the integration of foundry sand into CLSM, excavatable CLSM and structural CLSM containing different types of excess foundry sands were investigated through laboratory experiments. Foundry sand was approved to constitute a major component in CLSM. Regarding the integration of foundry sand into asphalt paving materials, the optimum asphalt content was determined for each mixture, as well as the bulk density, maximum density, asphalt absorption, and air voids at N{sub ini}, N{sub des}, and N{sub max}. It was found that foundry sands can be used as an aggregate in hot-mix asphalt production, but each sand should be evaluated individually. Foundry sands tend to lower the strength of mixtures and also may make them more susceptible to moisture damage. Finally, traditional anti-stripping additives may decrease the moisture sensitivity of a mixture containing foundry sand, but not to the level allowed by most highway agencies.« less

14 CFR 151.81 - Taxiway paving.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Taxiway paving. 151.81 Section 151.81 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Project Programming Standards § 151.81 Taxiway paving. (a) The construction...

14 CFR 151.81 - Taxiway paving.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Taxiway paving. 151.81 Section 151.81 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Project Programming Standards § 151.81 Taxiway paving. (a) The construction...

14 CFR 151.81 - Taxiway paving.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Taxiway paving. 151.81 Section 151.81 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Project Programming Standards § 151.81 Taxiway paving. (a) The construction...

14 CFR 151.81 - Taxiway paving.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Taxiway paving. 151.81 Section 151.81 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Project Programming Standards § 151.81 Taxiway paving. (a) The construction...

14 CFR 151.81 - Taxiway paving.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Taxiway paving. 151.81 Section 151.81 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Project Programming Standards § 151.81 Taxiway paving. (a) The construction...

Research on construction technology for orthotropic steel deck pavement of Haihe River Chunyi Bridge

NASA Astrophysics Data System (ADS)

Xue, Y. C.; Qian, Z. D.; Zhang, M.

2017-01-01

In order to ensure the good service quality of orthotropic steel deck pavement of Haihe River Chunyi Bridge in Tianjin, and to reduce the occurrence of pavement diseases like lateral and longitudinal cracks, the key working procedures such as steel deck cleaning, anticorrosive coating, bonding layer spraying, seam cutting, epoxy asphalt concrete’s mixing, transportation, paving and compaction were studied. The study was based on the main features of epoxy asphalt concrete which is the pavement materials of Haihe River Chunyi Bridge, and combined with the basic characteristics and construction conditions of Haihe River Chunyi Bridge. Furthermore, some processing measures like controlling time and temperature, continuous paving with two pavers, lateral feeding, and improving the compaction method were proposed. The project example shows that the processing measures can effectively solve the technical difficulties in the construction of orthotropic steel deck pavement of Haihe River Chunyi Bridge, can greatly improve the construction speed and quality, and can provide reference for the same kinds of orthotropic steel deck pavement construction.

Faxing Structures to the Moon: Freeform Additive Construction System (FACS)

NASA Technical Reports Server (NTRS)

Howe, A. Scott; Wilcox, Brian; McQuin, Christopher; Townsend, Julie; Rieber, Richard; Barmatz, Martin; Leichty, John

2013-01-01

Using the highly articulated All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) robotic mobility system as a precision positioning tool, a variety of print head technologies can be used to 3D print large-scale in-situ structures on planetary surfaces such as the moon or Mars. In effect, in the same way CAD models can be printed in a 3D printer, large-scale structures such as walls, vaults, domes, berms, paving, trench walls, and other insitu derived elements can be FAXed to the planetary surface and built in advance of the arrival of crews, supplementing equipment and materials brought from earth. This paper discusses the ATHLETE system as a mobility / positioning platform, and presents several options for large-scale additive print head technologies, including tunable microwave "sinterator" approaches and in-situ concrete deposition. The paper also discusses potential applications, such as sintered-in-place habitat shells, radiation shielding, road paving, modular bricks, and prefabricated construction components.

The Papillomavirus Episteme: a major update to the papillomavirus sequence database.

PubMed

Van Doorslaer, Koenraad; Li, Zhiwen; Xirasagar, Sandhya; Maes, Piet; Kaminsky, David; Liou, David; Sun, Qiang; Kaur, Ramandeep; Huyen, Yentram; McBride, Alison A

2017-01-04

The Papillomavirus Episteme (PaVE) is a database of curated papillomavirus genomic sequences, accompanied by web-based sequence analysis tools. This update describes the addition of major new features. The papillomavirus genomes within PaVE have been further annotated, and now includes the major spliced mRNA transcripts. Viral genes and transcripts can be visualized on both linear and circular genome browsers. Evolutionary relationships among PaVE reference protein sequences can be analysed using multiple sequence alignments and phylogenetic trees. To assist in viral discovery, PaVE offers a typing tool; a simplified algorithm to determine whether a newly sequenced virus is novel. PaVE also now contains an image library containing gross clinical and histopathological images of papillomavirus infected lesions. Database URL: https://pave.niaid.nih.gov/. Published by Oxford University Press on behalf of Nucleic Acids Research 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Evaluation of Cement, Lime, and Asphalt Amended Municipal Solid Waste Incinerator Residues

DTIC Science & Technology

1989-09-01

the lime column over time ( Atlas & Bartha , 1987). Certainly, a more extensive evaluation of the lime amended residue’s microbial activity is required...4.02 ASTM D 1559 (1988) Annual Book of ASTM Standards: Road & Paving Materials; Traveled Surface Characteristics, Sec 4, Vol 4.03 Atlas , R. & R. Bartha ...1987) Microbial Ecology : Fundamentals & Applications, Benjamin-Cummings, Menlo, CA Barrow N., J. Bowden, A. Posner, & J. Quirk (1981) Describing the

Human-in-the-loop development of soft wearable robots

NASA Astrophysics Data System (ADS)

Walsh, Conor

2018-06-01

The field of soft wearable robotics offers the opportunity to wear robots like clothes to assist the movement of specific body parts or to endow the body with functionalities. Collaborative efforts of materials, apparel and robotics science have already led to the development of wearable technologies for physical therapy. Optimizing the human-robot system by human-in-the-loop approaches will pave the way for personalized soft wearable robots for a variety of applications.

Graphene-like layers as promising chemiresistive sensing material for detection of alcohols at low concentration

NASA Astrophysics Data System (ADS)

Gargiulo, Valentina; Alfano, Brigida; Di Capua, Roberto; Alfé, Michela; Vorokhta, Mykhailo; Polichetti, Tiziana; Massera, Ettore; Miglietta, Maria Lucia; Schiattarella, Chiara; Di Francia, Girolamo

2018-01-01

In the manifold of materials for Volatile Organic Compound (VOC) sensing, graphene related materials (GRMs) gain special attention thanks to their versatility and overall chemico-physical tunability as a function of specific applications. In this work, the sensing performances of graphene-like (GL) layers, a new material belonging to the GRM family, are tested against ethanol and n-butanol. Two typologies of GL samples were produced by employing two different approaches and tested in view of their application as VOC sensors. The experiments were performed under atmospheric pressure, in dry air, and at room temperature and demonstrated that the sensing capabilities are related to the film surface features. The results indicated that GL films are promising candidates for the detection of low concentrations of VOCs at room temperature. The present investigation thus paves the way for VOC sensing optimization using cost-effective and easily scalable materials.

Solar fuels photoanode materials discovery by integrating high-throughput theory and experiment

DOE PAGES

Yan, Qimin; Yu, Jie; Suram, Santosh K.; ...

2017-03-06

The limited number of known low-band-gap photoelectrocatalytic materials poses a significant challenge for the generation of chemical fuels from sunlight. Here, using high-throughput ab initio theory with experiments in an integrated workflow, we find eight ternary vanadate oxide photoanodes in the target band-gap range (1.2-2.8 eV). Detailed analysis of these vanadate compounds reveals the key role of VO 4 structural motifs and electronic band-edge character in efficient photoanodes, initiating a genome for such materials and paving the way for a broadly applicable high-throughput-discovery and materials-by-design feedback loop. Considerably expanding the number of known photoelectrocatalysts for water oxidation, our study establishesmore » ternary metal vanadates as a prolific class of photoanodematerials for generation of chemical fuels from sunlight and demonstrates our high-throughput theory-experiment pipeline as a prolific approach to materials discovery.« less

Solar fuels photoanode materials discovery by integrating high-throughput theory and experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Qimin; Yu, Jie; Suram, Santosh K.

The limited number of known low-band-gap photoelectrocatalytic materials poses a significant challenge for the generation of chemical fuels from sunlight. Here, using high-throughput ab initio theory with experiments in an integrated workflow, we find eight ternary vanadate oxide photoanodes in the target band-gap range (1.2-2.8 eV). Detailed analysis of these vanadate compounds reveals the key role of VO 4 structural motifs and electronic band-edge character in efficient photoanodes, initiating a genome for such materials and paving the way for a broadly applicable high-throughput-discovery and materials-by-design feedback loop. Considerably expanding the number of known photoelectrocatalysts for water oxidation, our study establishesmore » ternary metal vanadates as a prolific class of photoanodematerials for generation of chemical fuels from sunlight and demonstrates our high-throughput theory-experiment pipeline as a prolific approach to materials discovery.« less

Ultrathin nanosheets of Mn3O4: A new two-dimensional ferromagnetic material with strong magnetocrystalline anisotropy

NASA Astrophysics Data System (ADS)

Wu, Jun-Chi; Peng, Xu; Guo, Yu-Qiao; Zhou, Hao-Dong; Zhao, Ji-Yin; Ruan, Ke-Qin; Chu, Wang-Sheng; Wu, Changzheng

2018-06-01

Two-dimensional (2D) materials with robust ferromagnetism have played a key role in realizing nextgeneration spin-electronic devices, but many challenges remain, especially the lack of intrinsic ferromagnetic behavior in almost all 2D materials. Here, we highlight ultrathin Mn3O4 nanosheets as a new 2D ferromagnetic material with strong magnetocrystalline anisotropy. Magnetic measurements along the in-plane and out-of-plane directions confirm that the out-of-plane direction is the easy axis. The 2D-confined environment and Rashba-type spin-orbit coupling are thought to be responsible for the magnetocrystalline anisotropy. The robust ferromagnetism in 2D Mn3O4 nanosheets with magnetocrystalline anisotropy not only paves a new way for realizing the intrinsic ferromagnetic behavior in 2D materials but also provides a novel candidate for building next-generation spin-electronic devices.

On-chip spectroscopy with thermally tuned high-Q photonic crystal cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liapis, Andreas C., E-mail: andreas.liapis@gmail.com; Gao, Boshen; Siddiqui, Mahmudur R.

2016-01-11

Spectroscopic methods are a sensitive way to determine the chemical composition of potentially hazardous materials. Here, we demonstrate that thermally tuned high-Q photonic crystal cavities can be used as a compact high-resolution on-chip spectrometer. We have used such a chip-scale spectrometer to measure the absorption spectra of both acetylene and hydrogen cyanide in the 1550 nm spectral band and show that we can discriminate between the two chemical species even though the two materials have spectral features in the same spectral region. Our results pave the way for the development of chip-size chemical sensors that can detect toxic substances.

Mechanical behavior of nanocrystalline NaCl islands on Cu(111).

PubMed

Bombis, Ch; Ample, F; Mielke, J; Mannsberger, M; Villagómez, C J; Roth, Ch; Joachim, C; Grill, L

2010-05-07

The mechanical response of ultrathin NaCl crystallites of nanometer dimensions upon manipulation with the tip of a scanning tunneling microscope (STM) is investigated, expanding STM manipulation to various nanostructuring modes of inorganic materials as cutting, moving, and cracking. In the light of theoretical calculations, our results reveal that atomic-scale NaCl islands can behave elastically and follow a classical Hooke's law. When the elastic limit of the nanocrystallites is reached, the STM tip induces atomic dislocations and consequently the regime of plastic deformation is entered. Our methodology is paving the way to understand the mechanical behavior and properties of other nanoscale materials.

Disposable chemical sensors and biosensors made on cellulose paper.

PubMed

Kim, Joo-Hyung; Mun, Seongcheol; Ko, Hyun-U; Yun, Gyu-Young; Kim, Jaehwan

2014-03-07

Most sensors are based on ceramic or semiconducting substrates, which have no flexibility or biocompatibility. Polymer-based sensors have been the subject of much attention due to their ability to collect molecules on their sensing surface with flexibility. Beyond polymer-based sensors, the recent discovery of cellulose as a smart material paved the way to the use of cellulose paper as a potential candidate for mechanical as well as electronic applications such as actuators and sensors. Several different paper-based sensors have been investigated and suggested. In this paper, we review the potential of cellulose materials for paper-based application devices, and suggest their feasibility for chemical and biosensor applications.

Project P.A.V.E. Evaluation. Technical Report 1977-78. Publication Number: 77.49.

ERIC Educational Resources Information Center

Eglsaer, Richard; Matuszek, Paula

Project PAVE was implemented in Travis High School, Austin, Texas, to extend and coordinate services for certain high school special education students. Four components were crucial to the Project PAVE model: parental involvement, academic achievement, vocational programing, and extracurricular opportunities. The project evaluation, conducted in…

14 CFR 151.80 - Runway paving: Additional runway; other conditions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Runway paving: Additional runway; other conditions. 151.80 Section 151.80 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Project Programming Standards § 151.80 Runway paving...

14 CFR 151.80 - Runway paving: Additional runway; other conditions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Runway paving: Additional runway; other conditions. 151.80 Section 151.80 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Project Programming Standards § 151.80 Runway paving...

14 CFR 151.80 - Runway paving: Additional runway; other conditions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Runway paving: Additional runway; other conditions. 151.80 Section 151.80 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Project Programming Standards § 151.80 Runway paving...

14 CFR 151.79 - Runway paving: Second runway; wind conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Runway paving: Second runway; wind conditions. 151.79 Section 151.79 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Project Programming Standards § 151.79 Runway paving...

14 CFR 151.80 - Runway paving: Additional runway; other conditions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Runway paving: Additional runway; other conditions. 151.80 Section 151.80 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Project Programming Standards § 151.80 Runway paving...

14 CFR 151.80 - Runway paving: Additional runway; other conditions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Runway paving: Additional runway; other conditions. 151.80 Section 151.80 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIRPORTS FEDERAL AID TO AIRPORTS Project Programming Standards § 151.80 Runway paving...

Research Updates: The three M's (materials, metrology, and modeling) together pave the path to future nanoelectronic technologies

NASA Astrophysics Data System (ADS)

King, Sean W.; Simka, Harsono; Herr, Dan; Akinaga, Hiro; Garner, Mike

2013-10-01

Recent discussions concerning the continuation of Moore's law have focused on announcements by several major corporations to transition from traditional 2D planar to new 3D multi-gate field effect transistor devices. However, the growth and progression of the semiconductor microelectronics industry over the previous 4 decades has been largely driven by combined advances in new materials, lithography, and materials related process technologies. Looking forward, it is therefore anticipated that new materials and materials technologies will continue to play a significant role in both the pursuit of Moore's law and the evolution of the industry. In this research update, we discuss and illustrate some of the required and anticipated materials innovations that could potentially lead to the continuation of Moore's law for another decade (or more). We focus primarily on the innovations needed to achieve single digit nanometer technologies and illustrate how at these dimensions not only new materials but new metrologies and computational modeling will be needed.

An economic analysis of alternative paving materials

NASA Astrophysics Data System (ADS)

Mustain, J. L.

1982-12-01

The purpose of this paper is to present a means for economic analysis of alternative equivalent pavement designs, considering such factors as initial construction cost, annual maintenance cost, salvage value and the various intangibles which occur during the analysis period. Having established a means of economic comparison, it is then the intent of this paper to show that Portland Cement Concrete has been and is a viable pavement alternative and ought to receive due consideration in the military construction program.

Dreamy Draw Dam - Master Plan and Feature Design, New River and Phoenix City Streams, Arizona.

DTIC Science & Technology

1981-09-01

Carnegiea gigantea Saguaro Cactus Ferocactus wislizenii Fishhook Barrel Cactus The area north of the paved assembly area will be recontoured to...brittlebush, triangle bursage, little leaf palo verde, ocotillo, and various cacti species (pls. 8 and 9). Destructive past land uses have contributed to the...is well established. Plants used include saguaro , ocotillo, and Bermuda grass. The areas used for borrowing of material in construction of the 18 dam

Regional analysis of the effect of paved roads on sodium and chloride in lakes.

PubMed

Kelting, Daniel L; Laxson, Corey L; Yerger, Elizabeth C

2012-05-15

Salinization of surface water from sodium chloride (road salt) applied to paved roads is a widely recognized environmental concern in the northern hemisphere, yet practical information to improve winter road management to reduce the environmental impacts of this deicer is lacking. The purpose of our study was to provide such information by developing baseline concentrations for sodium and chloride for lakes in watersheds without paved roads, and then determining the relationship between these ions and density, type, and proximity of paved roads to shoreline. We used average summer (June-September) sodium and chloride data for 138 lakes combined in a watershed based analysis of paved road networks in the Adirondack Park of New York, U.S.A. The watersheds used in our study represented a broad range in paved road density and type, 56 of which had no paved roads. Median lake sodium and chloride concentrations in these 56 watersheds averaged 0.55 and 0.24 mg/L, respectively. In contrast, the median sodium and chloride concentrations for the 82 lakes in watersheds with paved roads were 3.60 and 7.22 mg/L, respectively. Paved road density (lane-km/km(2)) was positively correlated with sodium and chloride concentrations, but only state roads were significantly correlated with sodium and chloride while local roads were not. State road density alone explained 84 percent of the variation in both ions. We also successfully modeled the relationship between road proximity to shoreline and sodium and chloride concentrations in lakes, which allowed us to identify sections of road that contributed more to explaining the variation in sodium and chloride in lakes. This model and our approach could be used as part of larger efforts to identify environmentally sensitive areas where alternative winter road management treatments should be applied. Copyright © 2012 Elsevier Ltd. All rights reserved.

Advances in Nanotechnology for Restorative Dentistry.

PubMed

Khurshid, Zohaib; Zafar, Muhammad; Qasim, Saad; Shahab, Sana; Naseem, Mustafa; AbuReqaiba, Ammar

2015-02-16

Rationalizing has become a new trend in the world of science and technology. Nanotechnology has ascended to become one of the most favorable technologies, and one which will change the application of materials in different fields. The quality of dental biomaterials has been improved by the emergence of nanotechnology. This technology manufactures materials with much better properties or by improving the properties of existing materials. The science of nanotechnology has become the most popular area of research, currently covering a broad range of applications in dentistry. This review describes the basic concept of nanomaterials, recent innovations in nanomaterials and their applications in restorative dentistry. Advances in nanotechnologies are paving the future of dentistry, and there are a plenty of hopes placed on nanomaterials in terms of improving the health care of dental patients.

Advances in Nanotechnology for Restorative Dentistry

PubMed Central

Khurshid, Zohaib; Zafar, Muhammad; Qasim, Saad; Shahab, Sana; Naseem, Mustafa; AbuReqaiba, Ammar

2015-01-01

Rationalizing has become a new trend in the world of science and technology. Nanotechnology has ascended to become one of the most favorable technologies, and one which will change the application of materials in different fields. The quality of dental biomaterials has been improved by the emergence of nanotechnology. This technology manufactures materials with much better properties or by improving the properties of existing materials. The science of nanotechnology has become the most popular area of research, currently covering a broad range of applications in dentistry. This review describes the basic concept of nanomaterials, recent innovations in nanomaterials and their applications in restorative dentistry. Advances in nanotechnologies are paving the future of dentistry, and there are a plenty of hopes placed on nanomaterials in terms of improving the health care of dental patients. PMID:28787967

Comparison of human exposure pathways in an urban brownfield: reduced risk from paving roads.

PubMed

James, Kyle; Farrell, Richard E; Siciliano, Steven D

2012-10-01

Risk assessments often do not quantify the risk associated with soil inhalation. This pathway generally makes a negligible contribution to the cumulative risk, because soil ingestion is typically the dominant exposure pathway. Conditions in northern or rural centers in Canada characterized by large areas of exposed soil, including unpaved roads, favor the resuspension of soil particles, making soil inhalation a relevant risk pathway. The authors determined and compared human exposure to metals and polycyclic aromatic hydrocarbons (PAHs) from soil ingestion and inhalation and analyzed the carcinogenic and noncarcinogenic risks before and after roads were paved in a northern community. To determine the inhalation exposure, three size fractions of airborne particulate matter were collected (total suspended particulates [TSP], particulate matter with an aerodynamic diameter less than 10 µm [PM10], and particulate matter with an aerodynamic diameter less than 2.5 µm [PM2.5]) before and after roads were paved. Road paving reduced the concentration of many airborne contaminants by 25 to 75%, thus reducing risk. For example, before paving, the carcinogenic risk associated with inhalation of Cr was 3.4 excess cancers per 100,000 people exposed, whereas after paving, this risk was reduced to 1.6 in 100,000. Paving roads reduced the concentrations of total suspended particulates (TSP; p < 0.1) and PM10 (p < 0.05) but not PM25. Consequently, the ingestion of inhaled soil particles was substantially reduced. The authors conclude that resuspended soil is likely an important source of risk for many northern communities and that paving roads is an effective method of reducing risk from the inhalation of soil particles. Copyright © 2012 SETAC.

Nanoporous Metallic Networks: Fabrication, Optical Properties, and Applications.

PubMed

Ron, Racheli; Haleva, Emir; Salomon, Adi

2018-05-17

Nanoporous metallic networks are a group of porous materials made of solid metals with suboptical wavelength sizes of both particles and voids. They are characterized by unique optical properties, as well as high surface area and permeability of guest materials. As such, they attract a great focus as novel materials for photonics, catalysis, sensing, and renewable energy. Their properties together with the ability for scaling-up evoke an increased interest also in the industrial field. Here, fabrication techniques of large-scale metallic networks are discussed, and their interesting optical properties as well as their applications are considered. In particular, the focus is on disordered systems, which may facilitate the fabrication technique, yet, endow the three-dimensional (3D) network with distinct optical properties. These metallic networks bridge the nanoworld into the macroscopic world, and therefore pave the way to the fabrication of innovative materials with unique optoelectronic properties. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A deterministic guide for material and mode dependence of on-chip electro-optic modulator performance

NASA Astrophysics Data System (ADS)

Amin, Rubab; Suer, Can; Ma, Zhizhen; Sarpkaya, Ibrahim; Khurgin, Jacob B.; Agarwal, Ritesh; Sorger, Volker J.

2017-10-01

Electro-optic modulation is a key function in optical data communication and possible future optical computing engines. The performance of modulators intricately depends on the interaction between the actively modulated material and the propagating waveguide mode. While high-performing modulators were demonstrated before, the approaches were taken as ad-hoc. Here we show the first systematic investigation to incorporate a holistic analysis for high-performance and ultra-compact electro-optic modulators on-chip. We show that intricate interplay between active modulation material and optical mode plays a key role in the device operation. Based on physical tradeoffs such as index modulation, loss, optical confinement factors and slow-light effects, we find that bias-material-mode regions exist where high phase modulation and high loss (absorption) modulation is found. This work paves the way for a holistic design rule of electro-optic modulators for on-chip integration.

Mechanical properties on geopolymer brick: A review

NASA Astrophysics Data System (ADS)

Deraman, L. M.; Abdullah, M. M. A.; Ming, L. Y.; Ibrahim, W. M. W.; Tahir, M. F. M.

2017-09-01

Bricks has stand for many years as durable construction substantial, especially in the area of civil engineering to construct buildings. Brick commonly used in the structure of buildings as a construction wall, cladding, facing perimeter, paving, garden wall and flooring. The contribution of ordinary Portland cement (OPC) in cement bricks production worldwide to greenhouse gas emissions. Due to this issue, some researchers have done their study with other materials to produce bricks, especially as a by-product material. Researchers take effort in this regard to synthesizing from by-product materials such as fly ash, bottom ash and kaolin that are rich in silicon and aluminium in the development of inorganic alumina-silicate polymer, called geopolymer Geopolymer is a polymerization reaction between various aluminosilicate oxides with silicates solution or alkali hydroxide solution forming polymerized Si-O-Al-O bonds. This paper summarized some research finding of mechanical properties of geopolymer brick using by-product materials.

Giant switchable photovoltaic effect in organometal trihalide perovskite devices

NASA Astrophysics Data System (ADS)

Xiao, Zhengguo; Yuan, Yongbo; Shao, Yuchuan; Wang, Qi; Dong, Qingfeng; Bi, Cheng; Sharma, Pankaj; Gruverman, Alexei; Huang, Jinsong

2015-02-01

Organolead trihalide perovskite (OTP) materials are emerging as naturally abundant materials for low-cost, solution-processed and highly efficient solar cells. Here, we show that, in OTP-based photovoltaic devices with vertical and lateral cell configurations, the photocurrent direction can be switched repeatedly by applying a small electric field of <1 V μm-1. The switchable photocurrent, generally observed in devices based on ferroelectric materials, reached 20.1 mA cm-2 under one sun illumination in OTP devices with a vertical architecture, which is four orders of magnitude larger than that measured in other ferroelectric photovoltaic devices. This field-switchable photovoltaic effect can be explained by the formation of reversible p-i-n structures induced by ion drift in the perovskite layer. The demonstration of switchable OTP photovoltaics and electric-field-manipulated doping paves the way for innovative solar cell designs and for the exploitation of OTP materials in electrically and optically readable memristors and circuits.

Shape memory polymer network with thermally distinct elasticity and plasticity.

PubMed

Zhao, Qian; Zou, Weike; Luo, Yingwu; Xie, Tao

2016-01-01

Stimuli-responsive materials with sophisticated yet controllable shape-changing behaviors are highly desirable for real-world device applications. Among various shape-changing materials, the elastic nature of shape memory polymers allows fixation of temporary shapes that can recover on demand, whereas polymers with exchangeable bonds can undergo permanent shape change via plasticity. We integrate the elasticity and plasticity into a single polymer network. Rational molecular design allows these two opposite behaviors to be realized at different temperature ranges without any overlap. By exploring the cumulative nature of the plasticity, we demonstrate easy manipulation of highly complex shapes that is otherwise extremely challenging. The dynamic shape-changing behavior paves a new way for fabricating geometrically complex multifunctional devices.

Electromagnetic field tapering using all-dielectric gradient index materials.

PubMed

Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

2016-07-28

The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes.

Shape Memory Polymers for Body Motion Energy Harvesting and Self-Powered Mechanosensing.

PubMed

Liu, Ruiyuan; Kuang, Xiao; Deng, Jianan; Wang, Yi-Cheng; Wang, Aurelia C; Ding, Wenbo; Lai, Ying-Chih; Chen, Jun; Wang, Peihong; Lin, Zhiqun; Qi, H Jerry; Sun, Baoquan; Wang, Zhong Lin

2018-02-01

Growing demand in portable electronics raises a requirement to electronic devices being stretchable, deformable, and durable, for which functional polymers are ideal choices of materials. Here, the first transformable smart energy harvester and self-powered mechanosensation sensor using shape memory polymers is demonstrated. The device is based on the mechanism of a flexible triboelectric nanogenerator using the thermally triggered shape transformation of organic materials for effectively harvesting mechanical energy. This work paves a new direction for functional polymers, especially in the field of mechanosensation for potential applications in areas such as soft robotics, biomedical devices, and wearable electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ab Initio Molecular-Dynamics Simulation of Neuromorphic Computing in Phase-Change Memory Materials.

PubMed

Skelton, Jonathan M; Loke, Desmond; Lee, Taehoon; Elliott, Stephen R

2015-07-08

We present an in silico study of the neuromorphic-computing behavior of the prototypical phase-change material, Ge2Sb2Te5, using ab initio molecular-dynamics simulations. Stepwise changes in structural order in response to temperature pulses of varying length and duration are observed, and a good reproduction of the spike-timing-dependent plasticity observed in nanoelectronic synapses is demonstrated. Short above-melting pulses lead to instantaneous loss of structural and chemical order, followed by delayed partial recovery upon structural relaxation. We also investigate the link between structural order and electrical and optical properties. These results pave the way toward a first-principles understanding of phase-change physics beyond binary switching.

High-Performance WSe2 Complementary Metal Oxide Semiconductor Technology and Integrated Circuits.

PubMed

Yu, Lili; Zubair, Ahmad; Santos, Elton J G; Zhang, Xu; Lin, Yuxuan; Zhang, Yuhao; Palacios, Tomás

2015-08-12

Because of their extraordinary structural and electrical properties, two-dimensional materials are currently being pursued for applications such as thin-film transistors and integrated circuit. One of the main challenges that still needs to be overcome for these applications is the fabrication of air-stable transistors with industry-compatible complementary metal oxide semiconductor (CMOS) technology. In this work, we experimentally demonstrate a novel high performance air-stable WSe2 CMOS technology with almost ideal voltage transfer characteristic, full logic swing and high noise margin with different supply voltages. More importantly, the inverter shows large voltage gain (∼38) and small static power (picowatts), paving the way for low power electronic system in 2D materials.

Electroactive Polymers as Artificial Muscles: Capabilities, Potentials and Challenges

NASA Technical Reports Server (NTRS)

Bar-Cohen, Yoseph

2000-01-01

The low density and the relative ease of shaping made polymers highly attractive materials and they are increasingly being chosen for aerospace applications. Polymer matrix composite materials significantly impacted the construction of high performance aircraft components and structures. In recent years, the resilience characteristics of polymers made them attractive to the emerging field of inflatable structures. Balloons were used to cushion the deployment of the Mars Pathfinder lander on July 4, 1997, paving the way for the recent large number of related initiatives. Inflatable structures are now being used to construct a rover, aerial vehicles, telescopes, radar antennas, and others. Some of these applications have reached space flight experiments, whereas others are now at advanced stages of development.

Perfect Undetectable Acoustic Device from Fabry-Pérot Resonances

NASA Astrophysics Data System (ADS)

Chen, Huanyang; Zhou, Yangyang; Zhou, Mengying; Xu, Lin; Liu, Qing Huo

2018-02-01

Transformation acoustics is a method to design novel acoustic devices, while the complexity of the material parameters hinders its progress. In this paper, we analytically present a three-dimensional perfect undetectable acoustic device from Fabry-Pérot resonances and confirm its functionality from Mie theory. Such a mechanism goes beyond the traditional transformation acoustics. In addition, such a reduced version can be realized by holey-structured metamaterials. Our theory paves a way to the implementation of three-dimensional transformation acoustic devices.

Identification of Candidate Zero Maintenance Paving Materials. Volume 1

DTIC Science & Technology

1977-05-01

an anhydrous calcium sulfoaluminate as a way to control ettringite-formarion reactions and patented it as an invention on 18 October 1961. Another... Sulfoaluminates of Calcium as Stable and Meta- stable Phases and Study of Portion of the Five-Component System CaO-SO 3 -Al0 3-Na20-H 2O at 25C. Ph. D...Berkeley, Jun 1972. 242. , "Effect of Lime on Hydration of Pastes Containing Gypsum and Calcium Aluminates or Calcium Sulfoaluminate ," Journal, American

Metal segregation in hierarchically structured cathode materials for high-energy lithium batteries

DOE PAGES

Lin, Feng; Xin, Huolin L.; Nordlund, Dennis; ...

2016-01-11

Controlling surface and interfacial properties of battery materials is key to improving performance in rechargeable Li-ion devices. Surface reconstruction from a layered to a rock salt structure in metal oxide cathode materials is commonly observed and results in poor high-voltage cycling performance, impeding attempts to improve energy density. Hierarchically structured LiNi 0.4Mn 0.4Co 0.2O 2 (NMC-442) spherical powders, made by spray pyrolysis, exhibit local elemental distribution gradients that deviate from the global NMC-442 composition; specifically, they are Ni-rich and Mn-poor at particle surfaces. These materials demonstrate improved Coulombic efficiencies, discharge capacities, and high-voltage capacity retention in lithium half-cell configurations. Themore » subject powders show superior resistance against surface reconstruction due to the tailored surface chemistry, compared to conventional NMC-442 materials. This paves the way towards the development of a new generation of robust and stable high-energy NMC cathodes for Li-ion batteries.« less

C4N3H monolayer: A two-dimensional organic Dirac material with high Fermi velocity

NASA Astrophysics Data System (ADS)

Pan, Hongzhe; Zhang, Hongyu; Sun, Yuanyuan; Li, Jianfu; Du, Youwei; Tang, Nujiang

2017-11-01

Searching for two-dimensional (2D) organic Dirac materials, which have more adaptable practical applications compared with inorganic ones, is of great significance and has been ongoing. However, only two such materials with low Fermi velocity have been discovered so far. Herein, we report the design of an organic monolayer with C4N3H stoichiometry that possesses fascinating structure and good stability in its free-standing state. More importantly, we demonstrate that this monolayer is a semimetal with anisotropic Dirac cones and very high Fermi velocity. This Fermi velocity is roughly one order of magnitude larger than the largest velocity ever reported in 2D organic Dirac materials, and it is comparable to that in graphene. The Dirac states in this monolayer arise from the extended π -electron conjugation system formed by the overlapping 2 pz orbitals of carbon and nitrogen atoms. Our finding paves the way to a search for more 2D organic Dirac materials with high Fermi velocity.

Topologically nontrivial electronic states in CaSn3

NASA Astrophysics Data System (ADS)

Gupta, Sunny; Juneja, Rinkle; Shinde, Ravindra; Singh, Abhishek K.

2017-06-01

Based on the first-principles calculations, we theoretically propose topologically non-trivial states in a recently experimentally discovered superconducting material CaSn3. When the spin-orbit coupling (SOC) is ignored, the material is a host to three-dimensional topological nodal-line semimetal states. Drumhead like surface states protected by the coexistence of time-reversal and mirror symmetry emerge within the two-dimensional regions of the surface Brillouin zone connecting the nodal lines. When SOC is included, unexpectedly, each nodal line evolves into two Weyl nodes (W1 and W2) in this centrosymmetric material. Berry curvature calculations show that these nodes occur in a pair and act as either a source or a sink of Berry flux. This material also has unique surface states in the form of Fermi arcs, which unlike other known Weyl semimetals forms closed loops of surface states on the Fermi surface. Our theoretical realization of topologically non-trivial states in a superconducting material paves the way towards unraveling the interconnection between topological physics and superconductivity.

Bragg coherent diffractive imaging of single-grain defect dynamics in polycrystalline films

NASA Astrophysics Data System (ADS)

Yau, Allison; Cha, Wonsuk; Kanan, Matthew W.; Stephenson, G. Brian; Ulvestad, Andrew

2017-05-01

Polycrystalline material properties depend on the distribution and interactions of their crystalline grains. In particular, grain boundaries and defects are crucial in determining their response to external stimuli. A long-standing challenge is thus to observe individual grains, defects, and strain dynamics inside functional materials. Here we report a technique capable of revealing grain heterogeneity, including strain fields and individual dislocations, that can be used under operando conditions in reactive environments: grain Bragg coherent diffractive imaging (gBCDI). Using a polycrystalline gold thin film subjected to heating, we show how gBCDI resolves grain boundary and dislocation dynamics in individual grains in three-dimensional detail with 10-nanometer spatial and subangstrom displacement field resolution. These results pave the way for understanding polycrystalline material response under external stimuli and, ideally, engineering particular functions.

Bragg coherent diffractive imaging of single-grain defect dynamics in polycrystalline films

DOE PAGES

Yau, Allison; Cha, Wonsuk; Kanan, Matthew W.; ...

2017-05-19

Polycrystalline material properties depend on the distribution and interactions of their crystalline grains. In particular, grain boundaries and defects are crucial in determining their response to external stimuli. A long-standing challenge is thus to observe individual grains, defects, and strain dynamics inside functional materials. Here we report a technique capable of revealing grain heterogeneity, including strain fields and individual dislocations, that can be used under operando conditions in reactive environments: grain Bragg coherent diffractive imaging (gBCDI). Using a polycrystalline gold thin film subjected to heating, we show how gBCDI resolves grain boundary and dislocation dynamics in individual grains in three-dimensionalmore » detail with 10-nanometer spatial and subangstrom displacement field resolution. Finally, these results pave the way for understanding polycrystalline material response under external stimuli and, ideally, engineering particular functions.« less

Photodiodes based in La0.7Sr0.3MnO3/single layer MoS2 hybrid vertical heterostructures

NASA Astrophysics Data System (ADS)

Niu, Yue; Frisenda, Riccardo; Svatek, Simon A.; Orfila, Gloria; Gallego, Fernando; Gant, Patricia; Agraït, Nicolás; Leon, Carlos; Rivera-Calzada, Alberto; Pérez De Lara, David; Santamaria, Jacobo; Castellanos-Gomez, Andres

2017-09-01

The fabrication of artificial materials by stacking of individual two-dimensional (2D) materials is amongst one of the most promising research avenues in the field of 2D materials. Moreover, this strategy to fabricate new man-made materials can be further extended by fabricating hybrid stacks between 2D materials and other functional materials with different dimensionality making the potential number of combinations almost infinite. Among all these possible combinations, mixing 2D materials with transition metal oxides can result especially useful because of the large amount of interesting physical phenomena displayed separately by these two material families. We present a hybrid device based on the stacking of a single layer MoS2 onto a lanthanum strontium manganite (La0.7Sr0.3MnO3) thin film, creating an atomically thin device. It shows a rectifying electrical transport with a ratio of 103, and a photovoltaic effect with V oc up to 0.4 V. The photodiode behaviour arises as a consequence of the different doping character of these two materials. This result paves the way towards combining the efforts of these two large materials science communities.

Bi2S3microspheres grown on graphene sheets as low-cost counter-electrode materials for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Li, Guang; Chen, Xiaoshuang; Gao, Guandao

2014-02-01

In this work, we synthesized 3D Bi2S3 microspheres comprised of nanorods grown along the (211) facet on graphene sheets by a solvothermal route, and investigated its catalytic activities through I-V curves and conversion efficiency tests as the CE in DSSCs. Although the (211) facet has a large band gap for a Bi2S3 semiconductor, owing to the introduction of graphene into the system, its short-circuit current density, open-circuit voltage, fill factor, and efficiency were Jsc = 12.2 mA cm-2, Voc = 0.75 V, FF = 0.60, and η = 5.5%, respectively. By integrating it with graphene sheets, our material achieved the conversion efficiency of 5.5%, which is almost triple the best conversion efficiency value of the DSSCs with (211)-faceted 3D Bi2S3 without graphene (1.9%) reported in the latest literature. Since this conversion-efficient 3D material grown on the graphene sheets significantly improves its catalytic properties, it paves the way for designing and applying low-cost Pt-free CE materials in DSSC from inorganic nanostructures.In this work, we synthesized 3D Bi2S3 microspheres comprised of nanorods grown along the (211) facet on graphene sheets by a solvothermal route, and investigated its catalytic activities through I-V curves and conversion efficiency tests as the CE in DSSCs. Although the (211) facet has a large band gap for a Bi2S3 semiconductor, owing to the introduction of graphene into the system, its short-circuit current density, open-circuit voltage, fill factor, and efficiency were Jsc = 12.2 mA cm-2, Voc = 0.75 V, FF = 0.60, and η = 5.5%, respectively. By integrating it with graphene sheets, our material achieved the conversion efficiency of 5.5%, which is almost triple the best conversion efficiency value of the DSSCs with (211)-faceted 3D Bi2S3 without graphene (1.9%) reported in the latest literature. Since this conversion-efficient 3D material grown on the graphene sheets significantly improves its catalytic properties, it paves the way for designing and applying low-cost Pt-free CE materials in DSSC from inorganic nanostructures. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06093d

NanoSPD activity in Ufa and International Cooperation

NASA Astrophysics Data System (ADS)

Reshetnikova, N.; Salakhova, M.

2014-08-01

This report presents main achievements of R&D activities of the Institute of Physics of Advanced Materials of Ufa State Aviation Technical University (IPAM USATU, Ufa, Russia) with a special attention to innovative potential of nanostructured metals and alloys produced by the severe plastic deformation (SPD) techniques. Several examples of the first promising applications of bulk nanostructured materials (BNM) as well as potential competing technologies are considered and discussed. The authors would like to focus special emphasis on international cooperation in view of numerous emerging projects as well as different conferences and seminars that pave the way to close and fruitful cooperation, working visits and exchange of young scientists. The possibilities of international cooperation through various foundations and programs are considered.

Size and Electronic Modulation of Iridium Nanoparticles on Nitrogen Functionalized Carbon toward Advanced Electrocatalysts for Alkaline Water Splitting.

PubMed

Wang, Hua; Ming, Mei; Hu, Min; Xu, Caili; Wang, Yi; Zhang, Yun; Gao, Daojiang; Bi, Jian; Fan, Guangyin; Hu, Jin-Song

2018-06-14

Developing efficient catalytic materials for electrochemical water splitting is important. Herein, uniformly dispersed and size-controllable iridium (Ir) nanoparticles (NPs) were prepared using a nitrogen-functionalized carbon (Ir/CN) as the support. We found that nitrogen function can simultaneously modulate the size of Ir NPs to substantially enhance the catalytically active sites and adjust the electronic structure of Ir, thereby promoting electrocatalytic activity for water splitting. Consequently, the as-synthesized Ir/CN shows excellent electrocatalytic performance with overpotentials of 12 and 265 mV for hydrogen and oxygen evolution reactions in basic medium, respectively. These findings may pave a way for designing and synthesizing other similar materials as efficient catalysts for electrochemical water splitting.

Graphene based d-character Dirac Systems

NASA Astrophysics Data System (ADS)

Li, Yuanchang; Zhang, S. B.; Duan, Wenhui

From graphene to topological insulators, Dirac material continues to be the hot topics in condensed matter physics. So far, almost all of the theoretically predicted or experimentally observed Dirac materials are composed of sp -electrons. By using first-principles calculations, we find the new Dirac system of transition-metal intercalated epitaxial graphene on SiC(0001). Intrinsically different from the conventional sp Dirac system, here the Dirac-fermions are dominantly contributed by the transition-metal d-electrons, which paves the way to incorporate correlation effect with Dirac-cone physics. Many intriguing quantum phenomena are proposed based on this system, including quantum spin Hall effect with large spin-orbital gap, quantum anomalous Hall effect, 100% spin-polarized Dirac fermions and ferromagnet-to-topological insulator transition.

Silver metaphosphate glass wires inside silica fibers--a new approach for hybrid optical fibers.

PubMed

Jain, Chhavi; Rodrigues, Bruno P; Wieduwilt, Torsten; Kobelke, Jens; Wondraczek, Lothar; Schmidt, Markus A

2016-02-22

Phosphate glasses represent promising candidates for next-generation photonic devices due to their unique characteristics, such as vastly tunable optical properties, and high rare earth solubility. Here we show that silver metaphosphate wires with bulk optical properties and diameters as small as 2 µm can be integrated into silica fibers using pressure-assisted melt filling. By analyzing two types of hybrid metaphosphate-silica fibers, we show that the filled metaphosphate glass has only negligible higher attenuation and a refractive index that is identical to the bulk material. The presented results pave the way towards new fiber-type optical devices relying on metaphosphate glasses, which are promising materials for applications in nonlinear optics, sensing and spectral filtering.

Shape memory polymer network with thermally distinct elasticity and plasticity

PubMed Central

Zhao, Qian; Zou, Weike; Luo, Yingwu; Xie, Tao

2016-01-01

Stimuli-responsive materials with sophisticated yet controllable shape-changing behaviors are highly desirable for real-world device applications. Among various shape-changing materials, the elastic nature of shape memory polymers allows fixation of temporary shapes that can recover on demand, whereas polymers with exchangeable bonds can undergo permanent shape change via plasticity. We integrate the elasticity and plasticity into a single polymer network. Rational molecular design allows these two opposite behaviors to be realized at different temperature ranges without any overlap. By exploring the cumulative nature of the plasticity, we demonstrate easy manipulation of highly complex shapes that is otherwise extremely challenging. The dynamic shape-changing behavior paves a new way for fabricating geometrically complex multifunctional devices. PMID:26824077

Brazil's Cuiabá- Santarém (BR-163) Highway: the environmental cost of paving a soybean corridor through the Amazon.

PubMed

Fearnside, Philip M

2007-05-01

Brazil's Cuiabá-Santarém (BR-163) Highway provides a valuable example of ways in which decision-making procedures for infrastructure projects in tropical forest areas need to be reformulated in order to guarantee that environmental concerns are properly weighed. BR-163, which is slated to be paved as an export corridor for soybeans via the Amazon River, traverses an area that is largely outside of Brazilian government control. A climate of generalized lawlessness and impunity prevails, and matters related to environment and to land tenure are especially unregulated. Deforestation and illegal logging have accelerated in anticipation of highway paving. Paving would further speed forest loss in the area, as well as stimulate migration of land thieves (grileiros) to other frontiers. An argument is made that the highway should not be reconstructed and paved until after a state of law has been established and it has been independently certified that sufficient governance prevails to secure protected areas and enforce environmental legislation. A waiting period is needed after this is achieved before proceeding with the highway paving. Above all, the logical sequence of steps must be followed, whereby environmental costs are assessed, reported, and weighed prior to making de facto decisions on implementation of infrastructure projects. Deviation from this logical sequence is a common occurrence in many parts of the world, especially in tropical areas.

2D materials in electro-optic modulation: energy efficiency, electrostatics, mode overlap, material transfer and integration

NASA Astrophysics Data System (ADS)

Ma, Zhizhen; Hemnani, Rohit; Bartels, Ludwig; Agarwal, Ritesh; Sorger, Volker J.

2018-02-01

Here we discuss the physics of electro-optic modulators deploying 2D materials. We include a scaling laws analysis and show how energy-efficiency and speed change for three underlying cavity systems as a function of critical device length scaling. A key result is that the energy-per-bit of the modulator is proportional to the volume of the device, thus making the case for submicron-scale modulators possible deploying a plasmonic optical mode. We then show how Graphene's Pauli-blocking modulation mechanism is sensitive to the device operation temperature, whereby a reduction of the temperature enables a 10× reduction in modulator energy efficiency. Furthermore, we show how the high-index tunability of graphene is able to compensate for the small optical overlap factor of 2D-based material modulators, which is unlike classical silicon-based dispersion devices. Lastly, we demonstrate a novel method towards a 2D material printer suitable for cross-contamination free and on-demand printing. The latter paves the way to integrate 2D materials seamlessly into taped-out photonic chips.

Exposure to ultrafine particles in asphalt work.

PubMed

Elihn, Karine; Ulvestad, Bente; Hetland, Siri; Wallen, Anna; Randem, Britt Grethe

2008-12-01

An epidemiologic study has demonstrated that asphalt workers show increased loss of lung function and an increase of biomarkers of inflammation over the asphalt paving season. The aim of this study was to investigate which possible agent(s) causes the inflammatory reaction, with emphasis on ultrafine particles. The workers' exposure to total dust, polycyclic aromatic hydrocarbons, and NO(2) was determined by personal sampling. Exposure to ultrafine particles was measured by means of particle counters and scanning mobility particle sizer mounted on a van following the paving machine. The fractions of organic and elemental carbon were determined. Asphalt paving workers were exposed to ultrafine particles with medium concentration of about 3.4 x 10(4)/cm(3). Ultrafine particles at the paving site originated mainly from asphalt paving activities and traffic exhaust; most seemed to originate from asphalt fumes. Oil mist exceeded occupational limits on some occasions. Diesel particulate matter was measured as elemental carbon, which was low, around 3 microg/m(3). NO(2) and total dust did not exceed limits. Asphalt pavers were exposed to relatively high concentrations of ultrafine particles throughout their working day, with possible adverse health effects.

Characterizing the fabric of the urban environment: A case study of Greater Houston, Texas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rose, Leanna Shea; Akbari, Hashem; Taha, Haider

2003-01-15

In this report, the materials and various surface types that comprise a city are referred to as the ''urban fabric.'' Urban fabric data are needed in order to estimate the impact of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city, and to design effective urban environmental implementation programs. We discuss the results of a semi-automatic Monte-Carlo statistical approach used to develop data on surface-type distribution and city-fabric makeup (percentage of various surface-types) using aerial color orthophotography. The digital aerial photographs for Houston covered a total of about 52more » km2 (20 mi2). At 0.30-m resolution, there were approximately 5.8 x 108 pixels of data. Four major land-use types were examined: (1) commercial, (2) industrial, (3) educational, and (4) residential. On average, for the regions studied, vegetation covers about 39 percent of the area, roofs cover about 21 percent, and paved surfaces cover about 29 percent. For the most part, trees shade streets, parking lots, grass, and sidewalks. At ground level, i.e., view from below the vegetation canopies, paved surfaces cover about 32 percent of the study area. GLOBEIS model data from University of Texas and land-use/land-cover (LULC) information from the United States Geological Survey (USGS) were used to extrapolate these results from neighborhood scales to Greater Houston. It was found that in an area of roughly 3,430 km2, defining most of Greater Houston, over 56 percent is residential. The total roof area is about 740 km2, and the total paved surface area (roads, parking areas, sidewalks) covers about 1000 km2. Vegetation covers about 1,320 km2.« less

Spider Silk: Mother Nature's Bio-Superlens

NASA Astrophysics Data System (ADS)

Monks, James N.; Yan, Bing; Hawkins, Nicholas; Vollrath, Fritz; Wang, Zengbo

2016-09-01

This paper demonstrates a possible new microfiber bio near field lens that uses minor ampullate spider silk,spun from the Nephila edulis spider, to create a real time image of a surface using near field optical techniques. The microfiber bio lens is the world's first natural superlens created by exploring biological materials. The resolution of the surface image overcomes the diffraction limit, with the ability to resolve patterns at 100 nm under a standard white light source in reflection mode. This resolution offers further developments in superlens technology and paves the way for new bio optics.

Robust, directed assembly of fluorescent nanodiamonds.

PubMed

Kianinia, Mehran; Shimoni, Olga; Bendavid, Avi; Schell, Andreas W; Randolph, Steven J; Toth, Milos; Aharonovich, Igor; Lobo, Charlene J

2016-10-27

Arrays of fluorescent nanoparticles are highly sought after for applications in sensing, nanophotonics and quantum communications. Here we present a simple and robust method of assembling fluorescent nanodiamonds into macroscopic arrays. Remarkably, the yield of this directed assembly process is greater than 90% and the assembled patterns withstand ultra-sonication for more than three hours. The assembly process is based on covalent bonding of carboxyl to amine functional carbon seeds and is applicable to any material, and to non-planar surfaces. Our results pave the way to directed assembly of sensors and nanophotonics devices.

[Nano-particles--pharmaceutical "dwarves" with know-how].

PubMed

Ziegler, Andreas S

2008-12-01

Self-cleaning surface coatings, tooth paste with repair effect, mini fuel cells and extremely small data memories, which contain the knowledge of whole libraries: After "micro" in the 1980ies and "electronic" in the 1990ies, "nano" is the technological keyword of this decade. The new nano-materials fascinate laymen and experts alike. Also in pharmacy the advance into dimensions unattainable so far, paved the way for the formulation of new pharmaceutical preparations. The nanotechnology offers innovative answers to previously unresolved galenic and/or biopharmaceutical questions and offers unexpected possibilities for drug targeting.

Dynamical Cooper pairing in nonequilibrium electron-phonon systems

DOE PAGES

Knap, Michael; Babadi, Mehrtash; Refael, Gil; ...

2016-12-08

In this paper, we analyze Cooper pairing instabilities in strongly driven electron-phonon systems. The light-induced nonequilibrium state of phonons results in a simultaneous increase of the superconducting coupling constant and the electron scattering. We demonstrate that the competition between these effects leads to an enhanced superconducting transition temperature in a broad range of parameters. Finally, our results may explain the observed transient enhancement of superconductivity in several classes of materials upon irradiation with high intensity pulses of terahertz light, and may pave new ways for engineering high-temperature light-induced superconducting states.

Perfect absorption of modified-molybdenum-disulfide-based Tamm plasmonic structures

NASA Astrophysics Data System (ADS)

Wang, Xiaoyu; Wang, Jicheng; Hu, Zheng-Da; Sang, Tian; Feng, Yan

2018-06-01

The two-dimensional semiconductor materials of transition metal molybdenum disulfide display various special optical properties in the interaction of matter and light. In this work, we study the strong coupling between the two-dimensional materials’ excitons and Tamm plasmon polaritons (TPPs). To enhance the interaction between light and matter, we introduce the grating modulation in the traditional Tamm structure. By adjusting the structure parameters of the grating-modified Tamm system, we achieve perfect absorption in the visible region. Our research results will pave the way for the application of ultrathin polarization optical devices.

Theoretical Solution for Temperature Profile in Multi-layered Pavement Systems Subjected to Transient Thermal Loads

DTIC Science & Technology

2011-01-01

kcal/mm s ◦C) Geopolymer paste 2.0x10−7 PCC slab 5.1x10−7 Thermal diffusivity, α (mm2/s) Geopolymer 0.2 PCC slab 1.3 for the surface layer of airfield...concrete pavements. Geopolymer materials have desirable properties for serving as an alternative binder to traditional Portland cement in producing...high thermal stability. Thus it is possible to construct paving concrete made from a geopolymer binder on top of the ordinary concrete slab to limit

High–energy density nonaqueous all redox flow lithium battery enabled with a polymeric membrane

PubMed Central

Jia, Chuankun; Pan, Feng; Zhu, Yun Guang; Huang, Qizhao; Lu, Li; Wang, Qing

2015-01-01

Redox flow batteries (RFBs) are considered one of the most promising large-scale energy storage technologies. However, conventional RFBs suffer from low energy density due to the low solubility of the active materials in electrolyte. On the basis of the redox targeting reactions of battery materials, the redox flow lithium battery (RFLB) demonstrated in this report presents a disruptive approach to drastically enhancing the energy density of flow batteries. With LiFePO4 and TiO2 as the cathodic and anodic Li storage materials, respectively, the tank energy density of RFLB could reach ~500 watt-hours per liter (50% porosity), which is 10 times higher than that of a vanadium redox flow battery. The cell exhibits good electrochemical performance under a prolonged cycling test. Our prototype RFLB full cell paves the way toward the development of a new generation of flow batteries for large-scale energy storage. PMID:26702440

Asian consortium on computational materials science theme meeting on ;first principles analysis & experiment: Role in energy research; 22-24 september 2016, SRM University, Kattankulathur, Chennai, India (ACCMS-TM 2016)

NASA Astrophysics Data System (ADS)

Thapa, Ranjit; Kawazoe, Yoshiyuki

2017-10-01

The main objective of this meeting was to provide a platform for theoreticians and experimentalists working in the area of materials to come together and carry out cutting edge research in the field of energy by showcasing their ideas and innovations. The theme meeting was successful in attracting young researchers from both fields, sharing common research interests. Participation of more than 250 researchers in ACCMS-TM 2016 has successfully paved the way towards exchange of mutual research insights and establishment of promising research collaborations. To encourage the young participants' research efforts, three best posters, each named as ;KAWAZOE PRIZE; in theoretical category and two best posters named ;ACCMS-TM 2016 POSTER AWARD; for experimental contributions was selected. A new award named ;ACCMS MID-CAREER AWARD; for outstanding scientific contribution in the area of Computational Materials Science was constituted.

Wrinkled Few-Layer Graphene as Highly Efficient Load Bearer.

PubMed

Androulidakis, Charalampos; Koukaras, Emmanuel N; Rahova, Jaroslava; Sampathkumar, Krishna; Parthenios, John; Papagelis, Konstantinos; Frank, Otakar; Galiotis, Costas

2017-08-09

Multilayered graphitic materials are not suitable as load-bearers due to their inherent weak interlayer bonding (for example, graphite is a solid lubricant in certain applications). This situation is largely improved when two-dimensional (2D) materials such as a monolayer (SLG) graphene are employed. The downside in these cases is the presence of thermally or mechanically induced wrinkles which are ubiquitous in 2D materials. Here we set out to examine the effect of extensive large wavelength/amplitude wrinkling on the stress transfer capabilities of exfoliated simply supported graphene flakes. Contrary to common belief we present clear evidence that this type of "corrugation" enhances the load-bearing capacity of few-layer graphene as compared to "flat" specimens. This effect is the result of the significant increase of the graphene/polymer interfacial shear stress per increment of applied strain due to wrinkling and paves the way for designing affordable graphene composites with highly improved stress-transfer efficiency.

BiFeO3 Thin Films: A Playground for Exploring Electric-Field Control of Multifunctionalities

NASA Astrophysics Data System (ADS)

Yang, Jan-Chi; He, Qing; Yu, Pu; Chu, Ying-Hao

2015-07-01

A promising approach to the next generation of low-power, functional, and green nanoelectronics relies on advances in the electric-field control of lattice, charge, orbital, and spin degrees of freedom in novel materials. The possibility of electric-field control of these multiple materials functionalities offers interesting options across a range of modern technologies, including information communication, computing processes, data storage, active components, and functional electronics. This article reviews electric-field control and modulation of various degrees of freedom through the medium of multiferroic BiFeO3. Coexisting order parameters and inherent couplings in this materials system form a potent playground, enabling direct and indirect manipulation to obtain intriguing properties and functionalities with an electric stimulus. An in-depth understanding of those electrically controlled phenomena and breakthroughs is highlighted, paving a new route toward multifunctional nanoelectronics. This article concludes with a brief discussion on foreseeable challenges as well as future directions.

Active Enhancement of Slow Light Based on Plasmon-Induced Transparency with Gain Materials.

PubMed

Zhang, Zhaojian; Yang, Junbo; He, Xin; Han, Yunxin; Zhang, Jingjing; Huang, Jie; Chen, Dingbo; Xu, Siyu

2018-06-03

As a plasmonic analogue of electromagnetically induced transparency (EIT), plasmon-induced transparency (PIT) has drawn more attention due to its potential of realizing on-chip sensing, slow light and nonlinear effect enhancement. However, the performance of a plasmonic system is always limited by the metal ohmic loss. Here, we numerically report a PIT system with gain materials based on plasmonic metal-insulator-metal waveguide. The corresponding phenomenon can be theoretically analyzed by coupled mode theory (CMT). After filling gain material into a disk cavity, the system intrinsic loss can be compensated by external pump beam, and the PIT can be greatly fueled to achieve a dramatic enhancement of slow light performance. Finally, a double-channel enhanced slow light is introduced by adding a second gain disk cavity. This work paves way for a potential new high-performance slow light device, which can have significant applications for high-compact plasmonic circuits and optical communication.

High-energy density nonaqueous all redox flow lithium battery enabled with a polymeric membrane.

PubMed

Jia, Chuankun; Pan, Feng; Zhu, Yun Guang; Huang, Qizhao; Lu, Li; Wang, Qing

2015-11-01

Redox flow batteries (RFBs) are considered one of the most promising large-scale energy storage technologies. However, conventional RFBs suffer from low energy density due to the low solubility of the active materials in electrolyte. On the basis of the redox targeting reactions of battery materials, the redox flow lithium battery (RFLB) demonstrated in this report presents a disruptive approach to drastically enhancing the energy density of flow batteries. With LiFePO4 and TiO2 as the cathodic and anodic Li storage materials, respectively, the tank energy density of RFLB could reach ~500 watt-hours per liter (50% porosity), which is 10 times higher than that of a vanadium redox flow battery. The cell exhibits good electrochemical performance under a prolonged cycling test. Our prototype RFLB full cell paves the way toward the development of a new generation of flow batteries for large-scale energy storage.

Full space device optimization for solar cells.

PubMed

Baloch, Ahmer A B; Aly, Shahzada P; Hossain, Mohammad I; El-Mellouhi, Fedwa; Tabet, Nouar; Alharbi, Fahhad H

2017-09-20

Advances in computational materials have paved a way to design efficient solar cells by identifying the optimal properties of the device layers. Conventionally, the device optimization has been governed by single or double descriptors for an individual layer; mostly the absorbing layer. However, the performance of the device depends collectively on all the properties of the material and the geometry of each layer in the cell. To address this issue of multi-property optimization and to avoid the paradigm of reoccurring materials in the solar cell field, a full space material-independent optimization approach is developed and presented in this paper. The method is employed to obtain an optimized material data set for maximum efficiency and for targeted functionality for each layer. To ensure the robustness of the method, two cases are studied; namely perovskite solar cells device optimization and cadmium-free CIGS solar cell. The implementation determines the desirable optoelectronic properties of transport mediums and contacts that can maximize the efficiency for both cases. The resulted data sets of material properties can be matched with those in materials databases or by further microscopic material design. Moreover, the presented multi-property optimization framework can be extended to design any solid-state device.

When 2D Materials Meet Molecules: Opportunities and Challenges of Hybrid Organic/Inorganic van der Waals Heterostructures.

PubMed

Gobbi, Marco; Orgiu, Emanuele; Samorì, Paolo

2018-05-01

van der Waals heterostructures, composed of vertically stacked inorganic 2D materials, represent an ideal platform to demonstrate novel device architectures and to fabricate on-demand materials. The incorporation of organic molecules within these systems holds an immense potential, since, while nature offers a finite number of 2D materials, an almost unlimited variety of molecules can be designed and synthesized with predictable functionalities. The possibilities offered by systems in which continuous molecular layers are interfaced with inorganic 2D materials to form hybrid organic/inorganic van der Waals heterostructures are emphasized. Similar to their inorganic counterpart, the hybrid structures have been exploited to put forward novel device architectures, such as antiambipolar transistors and barristors. Moreover, specific molecular groups can be employed to modify intrinsic properties and confer new capabilities to 2D materials. In particular, it is highlighted how molecular self-assembly at the surface of 2D materials can be mastered to achieve precise control over position and density of (molecular) functional groups, paving the way for a new class of hybrid functional materials whose final properties can be selected by careful molecular design. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

MoS 2-on-MXene Heterostructures as Highly Reversible Anode Materials for Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Chi; Xie, Xiuqiang; Anasori, Babak

Two-dimensional (2D) heterostructured materials, combining the collective advantages of individual building blocks and synergistic properties, have spurred great interest as a new paradigm in materials science. The family of 2D transition-metal carbides and nitrides, MXenes, has emerged as an attractive platform to construct functional materials with enhanced performance for diverse applications. Here, we synthesized 2D MoS 2-on-MXene heterostructures through in situ sulfidation of Mo 2TiC 2Tx MXene. The computational results show that MoS 2-on-MXene heterostructures have metallic properties. Moreover, the presence of MXene leads to enhanced Li and Li2S adsorption during the intercalation and conversion reactions. These characteristics render themore » as-prepared MoS 2-on-MXene heterostructures stable Li-ion storage performance. In conclusion, this work paves the way to use MXene to construct 2D heterostructures for energy storage applications.« less

Anomalous acoustic dispersion in architected microlattice metamaterials

NASA Astrophysics Data System (ADS)

KröDel, Sebastian; Palermo, Antonio; Daraio, Chiara

The ability to control dispersion in acoustic metamaterials is crucial to realize acoustic filtering and rectification devices as well as perfect imaging using negative refractive index materials. Architected microlattice metamaterials immersed in fluid constitute a versatile platform for achieving such control. We investigate architected microlattice materials able to exploit locally resonant modes of their fundamental building blocks that couple with propagating acoustic waves. Using analytical, numerical and experimental methods we find that such lattice materials show a hybrid dispersion behavior governed by Biot's theory for long wavelengths and multiple scattering theory when wave frequency is close to the resonances of the building block. We identify the relevant geometric parameters to alter and control the group and phase velocities in this class of acoustic metamaterials. Furthermore, we fabricate small-scale acoustic metamaterial samples using high precision SLA additive manufacturing and test the resulting materials experimentally using a customized ultrasonic setup. This work paves the way for new acoustic devices based on microlattice metamaterials.

Giant switchable photovoltaic effect in organometal trihalide perovskite devices

DOE PAGES

Xiao, Zhengguo; Yuan, Yongbo; Shao, Yuchuan; ...

2014-12-08

Organolead trihalide perovskite (OTP) materials are emerging as naturally abundant materials for low-cost, solution-processed and highly efficient solar cells. Here, we show that, in OTP-based photovoltaic devices with vertical and lateral cell configurations, the photocurrent direction can be switched repeatedly by applying a small electric field of <1 V μm –1. The switchable photocurrent, generally observed in devices based on ferroelectric materials, reached 20.1 mA cm –2 under one sun illumination in OTP devices with a vertical architecture, which is four orders of magnitude larger than that measured in other ferroelectric photovoltaic devices. This field-switchable photovoltaic effect can be explainedmore » by the formation of reversible p–i–n structures induced by ion drift in the perovskite layer. Furthermore, the demonstration of switchable OTP photovoltaics and electric-field-manipulated doping paves the way for innovative solar cell designs and for the exploitation of OTP materials in electrically and optically readable memristors and circuits.« less

Designing Hysteresis with Dipolar Chains

NASA Astrophysics Data System (ADS)

Concha, Andrés; Aguayo, David; Mellado, Paula

2018-04-01

Materials that have hysteretic response to an external field are essential in modern information storage and processing technologies. A myriad of magnetization curves of several natural and artificial materials have previously been measured and each has found a particular mechanism that accounts for it. However, a phenomenological model that captures all the hysteresis loops and at the same time provides a simple way to design the magnetic response of a material while remaining minimal is missing. Here, we propose and experimentally demonstrate an elementary method to engineer hysteresis loops in metamaterials built out of dipolar chains. We show that by tuning the interactions of the system and its geometry we can shape the hysteresis loop which allows for the design of the softness of a magnetic material at will. Additionally, this mechanism allows for the control of the number of loops aimed to realize multiple-valued logic technologies. Our findings pave the way for the rational design of hysteretical responses in a variety of physical systems such as dipolar cold atoms, ferroelectrics, or artificial magnetic lattices, among others.

Cocrystals Strategy towards Materials for Near-Infrared Photothermal Conversion and Imaging.

PubMed

Wang, Yu; Zhu, Weigang; Du, Wenna; Liu, Xinfeng; Zhang, Xiaotao; Dong, Huanli; Hu, Wenping

2018-04-03

A cocrystal strategy with a simple preparation process is developed to prepare novel materials for near-infrared photothermal (PT) conversion and imaging. DBTTF and TCNB are selected as electron donor (D) and electron acceptor (A) to self-assemble into new cocrystals through non-covalent interactions. The strong D-A interaction leads to a narrow band gap with NIR absorption and that both the ground state and lowest-lying excited state are charge transfer states. Under the NIR laser illumination, the temperature of the cocrystal sharply increases in a short time with high PT conversion efficiency (η=18.8 %), which is due to the active non-radiative pathways and inhibition of radiative transition process, as revealed by femtosecond transient absorption spectroscopy. This is the first PT conversion cocrystal, which not only provides insights for the development of novel PT materials, but also paves the way of designing functional materials with appealing applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

MoS 2-on-MXene Heterostructures as Highly Reversible Anode Materials for Lithium-Ion Batteries

DOE PAGES

Chen, Chi; Xie, Xiuqiang; Anasori, Babak; ...

2018-01-02

Two-dimensional (2D) heterostructured materials, combining the collective advantages of individual building blocks and synergistic properties, have spurred great interest as a new paradigm in materials science. The family of 2D transition-metal carbides and nitrides, MXenes, has emerged as an attractive platform to construct functional materials with enhanced performance for diverse applications. Here, we synthesized 2D MoS 2-on-MXene heterostructures through in situ sulfidation of Mo 2TiC 2Tx MXene. The computational results show that MoS 2-on-MXene heterostructures have metallic properties. Moreover, the presence of MXene leads to enhanced Li and Li2S adsorption during the intercalation and conversion reactions. These characteristics render themore » as-prepared MoS 2-on-MXene heterostructures stable Li-ion storage performance. In conclusion, this work paves the way to use MXene to construct 2D heterostructures for energy storage applications.« less

Designing Hysteresis with Dipolar Chains.

PubMed

Concha, Andrés; Aguayo, David; Mellado, Paula

2018-04-13

Materials that have hysteretic response to an external field are essential in modern information storage and processing technologies. A myriad of magnetization curves of several natural and artificial materials have previously been measured and each has found a particular mechanism that accounts for it. However, a phenomenological model that captures all the hysteresis loops and at the same time provides a simple way to design the magnetic response of a material while remaining minimal is missing. Here, we propose and experimentally demonstrate an elementary method to engineer hysteresis loops in metamaterials built out of dipolar chains. We show that by tuning the interactions of the system and its geometry we can shape the hysteresis loop which allows for the design of the softness of a magnetic material at will. Additionally, this mechanism allows for the control of the number of loops aimed to realize multiple-valued logic technologies. Our findings pave the way for the rational design of hysteretical responses in a variety of physical systems such as dipolar cold atoms, ferroelectrics, or artificial magnetic lattices, among others.

Occupational exposure to asphalt mixture during road paving is related to increased mitochondria DNA copy number: a cross-sectional study.

PubMed

Xu, Yiyi; Lindh, Christian H; Jönsson, Bo A G; Broberg, Karin; Albin, Maria

2018-03-27

Asphalt workers are exposed to polyaromatic hydrocarbons (PAHs) from hot mix asphalt via both inhalation and dermal absorption. The use of crumb rubber modified (CRM) asphalt may result in higher exposure to PAHs and more adverse effects. Our aim is to assess occupational exposure to PAHs from conventional and CRM asphalt paving by measuring PAH metabolites in urine, and to investigate the effects on mitochondrial DNA copy number (mtDNAcn) and telomere length. We recruited 116 workers paving conventional asphalt, 51 workers paving CRM asphalt and 100 controls in Sweden, all males. A repeated-measures analysis included 31 workers paving both types of asphalt. Urine and blood samples were collected pre-working on Monday morning and post-working on Thursday afternoon after 4 days working. PAH metabolites: 1-hydroxypyrene (1-OH-PYR) and 2-hydroxyphenanthrene (2-OH-PH) were measured in urine by LC-MS/MS. Relative mtDNAcn and telomere length were measured by quantitative PCR. Conventional and CRM asphalt workers showed higher 1-OH-PYR and 2-OH-PH than controls (p < 0.001 for all). Relative mtDNAcn were 0.21 units (p < 0.001) higher in conventional asphalt workers and 0.13 units (p = 0.010) higher in CRM asphalt workers compared to controls. Relative telomere length did not differ across occupational groups, but it was positively associated with increment of 2-OH-PH (β = 0.075, p = 0.037) in asphalt workers. The repeated-measures analysis showed no difference in either increment of 1-OH-PYP, or changes in effect biomarkers (mtDNAcn or telomere length) between paving with conventional and CRM asphalt. Increment of 2-OH-PH was smaller after paving with CRM asphalt. Road asphalt paving in open areas resulted in PAHs exposure, as shown by elevation of PAH metabolites in urine. Asphalt workers may experience oxidative stress, evidenced by alternation in mtDNAcn; however the effects could not be fully explained by exposure to PAHs from the asphalt mixture.

Implementing GPS into Pave-IR.

DOT National Transportation Integrated Search

2009-03-01

To further enhance the capabilities of the Pave-IR thermal segregation detection system developed at the Texas Transportation Institute, researchers incorporated global positioning system (GPS) data collection into the thermal profiles. This GPS capa...

Reuse of steel slag in bituminous paving mixtures.

PubMed

Sorlini, Sabrina; Sanzeni, Alex; Rondi, Luca

2012-03-30

This paper presents a comprehensive study to evaluate the mechanical properties and environmental suitability of electric arc furnace (EAF) steel slag in bituminous paving mixtures. A variety of tests were executed on samples of EAF slag to characterize the physical, geometrical, mechanical and chemical properties as required by UNI EN specifications, focusing additionally on the volumetric expansion associated with hydration of free CaO and MgO. Five bituminous mixtures of aggregates for flexible road pavement were designed containing up to 40% of EAF slag and were tested to determine Marshall stability and indirect tensile strength. The leaching behaviour of slag samples and bituminous mixtures was evaluated according to the UNI EN leaching test. The tested slag showed satisfactory physical and mechanical properties and a release of pollutants generally below the limits set by the Italian code. Tests on volume stability of fresh materials confirmed that a period of 2-3 months is necessary to reduce effects of oxides hydration. The results of tests performed on bituminous mixtures with EAF slag were comparable with the performance of mixtures containing natural aggregates and the leaching tests provided satisfactory results. Copyright © 2012 Elsevier B.V. All rights reserved.

Paving fabrics for reducing reflective cracking

DOT National Transportation Integrated Search

1991-11-01

This research effort was part of ADOT's New Product Evaluation Program. The objective was to evaluate the construction and field performances of three commercially available paving fabrics; Paveprep, Glassgrid, and Tapecoat. The fabrics were designed...

Paving fabrics for reducing reflective cracking

DOT National Transportation Integrated Search

1989-12-01

This report documents the installation of three commercially available paving fabrics for the reduction of reflective cracking in asphalt overlays. The fabrics installed were Paveprep, Glassgrid, and Tapecoat. The test section is in Willcox, Arizona,...

All-terrain vehicle fatalities on paved roads, unpaved roads, and off-road: Evidence for informed roadway safety warnings and legislation.

PubMed

Denning, Gerene M; Jennissen, Charles A

2016-05-18

All-terrain vehicles (ATVs) are designed for off-highway use only, and many of their features create increased risk with roadway travel. Over half of all ATV-related fatalities occur on roadways, and nonfatal roadway crashes result in more serious injuries than those off the road. A number of jurisdictions have passed or have considered legislation allowing ATVs on public roadways, sometimes limiting them to those unpaved, arguing that they are safe for ATVs. However, no studies have determined the epidemiology of ATV-related fatalities on different road surface types. The objective of the study was to compare ATV-related deaths on paved versus unpaved roads and to contrast them with off-road fatalities. Retrospective descriptive and multivariable analyses were performed using U.S. Consumer Product Safety Commission fatality data from 1982 through 2012. After 1998, ATV-related deaths increased at twice the rate on paved versus unpaved roads. Still, 42% of all roadway deaths during the study period occurred on unpaved surfaces. States varied considerably, ranging from 18% to 79% of their ATV-related roadway deaths occurring on unpaved roads. Paved road crashes were more likely than those on unpaved surfaces to involve males, adolescents and younger adults, passengers, and collisions with other vehicles. Both the pattern of other vehicles involved in collisions and which vehicle hit the other were different for the 2 road types. Alcohol use was higher, helmet use was lower, and head injuries were more likely in paved versus unpaved roadway crashes. However, head injuries still occurred in 76% of fatalities on unpaved roads. Helmets were associated with lower proportions of head injuries among riders, regardless of road surface type. Relative to off-road crashes, both paved and unpaved roads were more likely to involve collisions with another vehicle. The vast majority of roadway crashes, however, did not involve a traffic collision on either paved or unpaved roads. Although differences were observed between paved and unpaved roads, our results show that riding on either represented significantly greater dangers than riding off the road. Many vehicle warnings specifically mention the risks of paved but not unpaved roads, yet we found 23 states with half or more of their roadway deaths on unpaved surfaces. Safety warnings should explicitly state the dangers of roadway riding regardless of surface type. These data further support laws/ordinances greatly restricting ATV riding on all types of public roadways.

Validity of empirical models of exposure in asphalt paving

PubMed Central

Burstyn, I; Boffetta, P; Burr, G; Cenni, A; Knecht, U; Sciarra, G; Kromhout, H

2002-01-01

Aims: To investigate the validity of empirical models of exposure to bitumen fume and benzo(a)pyrene, developed for a historical cohort study of asphalt paving in Western Europe. Methods: Validity was evaluated using data from the USA, Italy, and Germany not used to develop the original models. Correlation between observed and predicted exposures was examined. Bias and precision were estimated. Results: Models were imprecise. Furthermore, predicted bitumen fume exposures tended to be lower (-70%) than concentrations found during paving in the USA. This apparent bias might be attributed to differences between Western European and USA paving practices. Evaluation of the validity of the benzo(a)pyrene exposure model revealed a similar to expected effect of re-paving and a larger than expected effect of tar use. Overall, benzo(a)pyrene models underestimated exposures by 51%. Conclusions: Possible bias as a result of underestimation of the impact of coal tar on benzo(a)pyrene exposure levels must be explored in sensitivity analysis of the exposure–response relation. Validation of the models, albeit limited, increased our confidence in their applicability to exposure assessment in the historical cohort study of cancer risk among asphalt workers. PMID:12205236

Giant and universal magnetoelectric coupling in soft materials and concomitant ramifications for materials science and biology

NASA Astrophysics Data System (ADS)

Liu, Liping; Sharma, Pradeep

2013-10-01

Magnetoelectric coupling—the ability of a material to magnetize upon application of an electric field and, conversely, to polarize under the action of a magnetic field—is rare and restricted to a rather small set of exotic hard crystalline materials. Intense research activity has recently ensued on materials development, fundamental scientific issues, and applications related to this phenomenon. This tantalizing property, if present in adequate strength at room temperature, can be used to pave the way for next-generation memory devices such as miniature magnetic random access memories and multiple state memory bits, sensors, energy harvesting, spintronics, among others. In this Rapid Communication, we prove the existence of an overlooked strain mediated nonlinear mechanism that can be used to universally induce the giant magnetoelectric effect in all (sufficiently) soft dielectric materials. For soft polymer foams—which, for instance, may be used in stretchable electronics—we predict room-temperature magnetoelectric coefficients that are comparable to the best known (hard) composite materials created. We also argue, based on a simple quantitative model, that magnetoreception in some biological contexts (e.g., birds) most likely utilizes this very mechanism.

Adjoint-based optimization of mechanical performance in polycrystalline materials and structures through texture control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, Grace; Brown, Judith Alice; Bishop, Joseph E.

The texture of a polycrystalline material refers to the preferred orientation of the grains within the material. In metallic materials, texture can significantly affect the mechanical properties such as elastic moduli, yield stress, strain hardening, and fracture toughness. Recent advances in additive manufacturing of metallic materials offer the possibility in the not too distant future of controlling the spatial variation of texture. In this work, we investigate the advantages, in terms of mechanical performance, of allowing the texture to vary spatially. We use an adjoint-based gradient optimization algorithm within a finite element solver (COMSOL) to optimize several engineering quantities ofmore » interest in a simple structure (hole in a plate) and loading (uniaxial tension) condition. As a first step to general texture optimization, we consider the idealized case of a pure fiber texture in which the homogenized properties are transversely isotropic. In this special case, the only spatially varying design variables are the three Euler angles that prescribe the orientation of the homogenized material at each point within the structure. This work paves a new way to design metallic materials for tunable mechanical properties at the microstructure level.« less

Antisite defects in layered multiferroic CuCr0.9In0.1P2S6

NASA Astrophysics Data System (ADS)

He, Qian; Belianinov, Alex; Dziaugys, Andrius; Maksymovych, Petro; Vysochanskii, Yulian; Kalinin, Sergei V.; Borisevich, Albina Y.

2015-11-01

The CuCr1-xInxP2S6 system represents a large family of metal chalcogenophosphates that are unique and promising candidates for 2D materials with functionalities such as ferroelectricity. In this work, we carried out detailed microstructural and chemical characterization of these compounds using aberration-corrected STEM, in order to understand the origin of these different ordering phenomena. Quantitative STEM-HAADF imaging and analysis identified the stacking order of an 8-layer thin flake, which leads to the identification of anti-site In3+(Cu+) doping. We believe that these findings will pave the way towards understanding the ferroic coupling phenomena in van der Waals lamellar compounds, as well as their potential applications in 2-D electronics.The CuCr1-xInxP2S6 system represents a large family of metal chalcogenophosphates that are unique and promising candidates for 2D materials with functionalities such as ferroelectricity. In this work, we carried out detailed microstructural and chemical characterization of these compounds using aberration-corrected STEM, in order to understand the origin of these different ordering phenomena. Quantitative STEM-HAADF imaging and analysis identified the stacking order of an 8-layer thin flake, which leads to the identification of anti-site In3+(Cu+) doping. We believe that these findings will pave the way towards understanding the ferroic coupling phenomena in van der Waals lamellar compounds, as well as their potential applications in 2-D electronics. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04779j

Impact of nighttime paving operations on asphalt roughness behavior.

DOT National Transportation Integrated Search

2013-05-01

The relationship between nighttime construction scheduling and future road quality in terms of roughness was investigated. Research was three-phased: interviews with local leaders in paving, on-site observations, and historical data analyses. Intervi...

MnPAVE-Rigid 2.0

DOT National Transportation Integrated Search

2018-05-01

This project implemented additional features into MnPAVE-Rigid, leading to a new version of MnDOTs rigid pavement design software. The database of American Association of State Highway Transportation Officers (AASHTO) mechanistic-empirical (M-E) p...

Management of paved secondary roads.

DOT National Transportation Integrated Search

1991-01-01

This report provides the background for the development of a pavement management system for the paved roads of Virginia's secondary highway system. Included are descriptions of a study to develop an acceptable surface-condition rating system for surf...

Pavement edge treatment.

DOT National Transportation Integrated Search

2013-01-01

Four projects were built over two construction seasons using special devices attached to the paving machine that produces a 30 slope on the outside pavement edge instead of the near vertical drop-off common with conventional paving equipment. This ...

Superenhancers: novel opportunities for nanowire optoelectronics.

PubMed

Khudiyev, Tural; Bayindir, Mehmet

2014-12-16

Nanowires play a crucial role in the development of new generation optoelectronic devices ranging from photovoltaics to photodetectors, as these designs capitalize on the low material usage, utilize leaky-mode optical resonances and possess high conversion efficiencies associated with nanowire geometry. However, their current schemes lack sufficient absorption capacity demanded for their practical applicability, and more efficient materials cannot find widespread usage in these designs due to their rarity and cost. Here we suggest a novel and versatile nanoconcentrator scheme utilizing unique optical features of non-resonant Mie (NRM) scattering regime associated with low-index structures. The scattering regime is highly compatible with resonant Mie absorption effect taking place in nanowire absorbers. This technique in its optimized forms can provide up to 1500% total absorption enhancement, 400-fold material save and is suitable for large-area applications with significant area preservation compared to thin-film of same materials. Proposed superenhancer concept with its exceptional features such as broadband absorption enhancement, polarization immunity and material-independent manner paves the way for development of efficient nanowire photosensors or solar thermophotovoltaic devices and presents novel design opportunities for self-powered nanosystems.

Novel Layered Supercell Structure from Bi 2AlMnO 6 for Multifunctionalities

DOE PAGES

Li, Leigang; Boullay, Philippe; Lu, Ping; ...

2017-10-02

Layered materials, e.g., graphene and transition metal (di)chalcogenides, holding great promises in nanoscale device applications have been extensively studied in fundamental chemistry, solid state physics and materials research areas. In parallel, layered oxides (e.g., Aurivillius and Ruddlesden–Popper phases) present an attractive class of materials both because of their rich physics behind and potential device applications. In this work, we report a novel layered oxide material with self-assembled layered supercell structure consisting of two mismatch-layered sublattices of [Bi 3O 3+δ] and [MO 2] 1.84 (M = Al/Mn, simply named BAMO), i.e., alternative layered stacking of two mutually incommensurate sublattices made ofmore » a three-layer-thick Bi–O slab and a one-layer-thick Al/Mn–O octahedra slab in the out-of-plane direction. Strong room-temperature ferromagnetic and piezoelectric responses as well as anisotropic optical property have been demonstrated with great potentials in various device applications. Furthermore, the realization of the novel BAMO layered supercell structure in this work has paved an avenue toward exploring and designing new materials with multifunctionalities.« less

Thermal Analysis of Fluidized Bed and Fixed Bed Latent Heat Thermal Storage System

NASA Astrophysics Data System (ADS)

Beemkumar, N.; Karthikeyan, A.; Shiva Keshava Reddy, Kota; Rajesh, Kona; Anderson, A.

2017-05-01

Thermal energy storage technology is essential because its stores available energy at low cost. Objective of the work is to store the thermal energy in a most efficient method. This work is deal with thermal analysis of fluidized bed and fixed bed latent heat thermal storage (LHTS) system with different encapsulation materials (aluminium, brass and copper). D-Mannitol has been used as phase change material (PCM). Encapsulation material which is in orbicular shape with 4 inch diameter and 2 mm thickness orbicular shaped product is used. Therminol-66 is used as a heat transfer fluid (HTF). Arrangement of encapsulation material is done in two ways namely fluidized bed and fixed bed thermal storage system. Comparison was made between the performance of fixed bed and fluidized bed with different encapsulation material. It is observed that from the economical point of view aluminium in fluidized bed LHTS System has highest efficiency than copper and brass. The thermal energy storage system can be analyzed with fixed bed by varying mass flow rate of oil paves a way to find effective heat energy transfer.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Leigang; Boullay, Philippe; Lu, Ping

Layered materials, e.g., graphene and transition metal (di)chalcogenides, holding great promises in nanoscale device applications have been extensively studied in fundamental chemistry, solid state physics and materials research areas. In parallel, layered oxides (e.g., Aurivillius and Ruddlesden–Popper phases) present an attractive class of materials both because of their rich physics behind and potential device applications. In this work, we report a novel layered oxide material with self-assembled layered supercell structure consisting of two mismatch-layered sublattices of [Bi 3O 3+δ] and [MO 2] 1.84 (M = Al/Mn, simply named BAMO), i.e., alternative layered stacking of two mutually incommensurate sublattices made ofmore » a three-layer-thick Bi–O slab and a one-layer-thick Al/Mn–O octahedra slab in the out-of-plane direction. Strong room-temperature ferromagnetic and piezoelectric responses as well as anisotropic optical property have been demonstrated with great potentials in various device applications. Furthermore, the realization of the novel BAMO layered supercell structure in this work has paved an avenue toward exploring and designing new materials with multifunctionalities.« less

Negative capacitance in a ferroelectric capacitor.

PubMed

Khan, Asif Islam; Chatterjee, Korok; Wang, Brian; Drapcho, Steven; You, Long; Serrao, Claudy; Bakaul, Saidur Rahman; Ramesh, Ramamoorthy; Salahuddin, Sayeef

2015-02-01

The Boltzmann distribution of electrons poses a fundamental barrier to lowering energy dissipation in conventional electronics, often termed as Boltzmann Tyranny. Negative capacitance in ferroelectric materials, which stems from the stored energy of a phase transition, could provide a solution, but a direct measurement of negative capacitance has so far been elusive. Here, we report the observation of negative capacitance in a thin, epitaxial ferroelectric film. When a voltage pulse is applied, the voltage across the ferroelectric capacitor is found to be decreasing with time--in exactly the opposite direction to which voltage for a regular capacitor should change. Analysis of this 'inductance'-like behaviour from a capacitor presents an unprecedented insight into the intrinsic energy profile of the ferroelectric material and could pave the way for completely new applications.

Security Paving Company, Inc.: Consent Agreement and Proposed Final Order

EPA Pesticide Factsheets

Consent Agreement and Proposed Final Order (“Proposed Consent Agreement”), between the U.S. Environmental Protection Agency, Region 9 (“EPA”), and Security Paving Company (“Respondent”) to resolve a civil administrative penalty proceeding.

Evaluation of quick-dry asphalt paving seal (QDAPS).

DOT National Transportation Integrated Search

1987-10-01

Quick-Dry Asphalt Paving Seal (QDAPS) manufactured for Texas Refinery Corp. Fort Worth, Texas. : According to the manufacturer, the primary use for this product is "a moisture resistant preventative maintenance asphalt coating for coating and sealing...

Reexamination of cold weather paving specifications for bituminous concrete.

DOT National Transportation Integrated Search

1978-01-01

The cold weather paving specification for bituminous concrete adopted in 1970 was reexamined to determine its effectiveness and any need for revisions. Density and temperature measurements were obtained on five field projects and observations were ma...

ePave: A Self-Powered Wireless Sensor for Smart and Autonomous Pavement.

PubMed

Xiao, Jian; Zou, Xiang; Xu, Wenyao

2017-09-26

"Smart Pavement" is an emerging infrastructure for various on-road applications in transportation and road engineering. However, existing road monitoring solutions demand a certain periodic maintenance effort due to battery life limits in the sensor systems. To this end, we present an end-to-end self-powered wireless sensor-ePave-to facilitate smart and autonomous pavements. The ePave system includes a self-power module, an ultra-low-power sensor system, a wireless transmission module and a built-in power management module. First, we performed an empirical study to characterize the piezoelectric module in order to optimize energy-harvesting efficiency. Second, we developed an integrated sensor system with the optimized energy harvester. An adaptive power knob is designated to adjust the power consumption according to energy budgeting. Finally, we intensively evaluated the ePave system in real-world applications to examine the system's performance and explore the trade-off.

Fuel Cell Electric Vehicles: Paving the Way to Commercial Success -

Science.gov Websites

emissions. Photo by Dennis Schroeder, NREL Fuel Cell Electric Vehicles: Paving the Way to Commercial Success advanced vehicle ride-and-drive event at the NREL Education Center. Photo by Dennis Schroeder, NREL "

Cold weather paving requirements for bituminous concrete.

DOT National Transportation Integrated Search

1973-01-01

Cold weather paving specifications were developed from work by Corlew and Dickson, who used a computer solution to predict the cooling rate of bituminous concrete. Virginia had used a minimum atmospheric temperature as a criterion; however, it was ev...

Potential of used frying oil in paving material: solution to environmental pollution problem.

PubMed

Singh-Ackbarali, Dimple; Maharaj, Rean; Mohamed, Nazim; Ramjattan-Harry, Vitra

2017-05-01

The improper disposal of used frying oil (UFO) presents numerous ecological, environmental and municipal problems. Of great concern is the resultant blockage of municipal drainage systems and water treatment facilities, harm to wildlife when they become coated in it and detriment to aquatic life and ecosystems due to the depletion of the oxygen content in water bodies such as rivers and lakes that have become contaminated. Statistics show that in Trinidad and Tobago, in excess of one million liters of used cooking oil is collected annually from various restaurant chains. This paper investigated the potential of using UFO as a performance enhancing additive for road paving applications utilizing Trinidad Lake Asphalt (TLA) and Trinidad Petroleum Bitumen (TPB) as a mitigation strategy for improper UFO disposal. Modified blends containing various additions of UFO (2-10% wt) were prepared for the TLA and TPB asphaltic binders. Results demonstrated in terms of stiffness, increasing the dosage of UFO in TLA and TPB base binders resulted in a gradual decrease in stiffness (G* value decreased). In terms of elasticity, increasing the dosage of the UFO additive in TLA resulted in a general decrease in the elasticity of the blends indicated by an increase in phase angle or phase lag (δ). Increasing dosages of the UFO additive in TPB resulted in a significant decrease in δ where the most elastic blend was at the 6% UFO level. TLA and UFO-TLA modified blends exhibited significantly lower values of δ and higher values of G* confirming the superiority of the TLA material. Incorporation of the UFO in the blends led to a decrease in the rutting resistance and increase in the fatigue cracking resistance (decrease in G*/sinδ and G*sinδ, respectively). This study highlighted the potential for the reuse of UFO as an asphalt modifier capable of producing customized UFO modified asphaltic blends for special applications and confirms its feasibility as an environmentally attractive means of reusing the waste/hazardous UFO material locally.

Triggering nanoparticle surface ligand rearrangement via external stimuli: light-based actuation of biointerfaces

NASA Astrophysics Data System (ADS)

Tang, Zhenghua; Lim, Chang-Keun; Palafox-Hernandez, J. Pablo; Drew, Kurt L. M.; Li, Yue; Swihart, Mark T.; Prasad, Paras N.; Walsh, Tiffany R.; Knecht, Marc R.

2015-08-01

Bio-molecular non-covalent interactions provide a powerful platform for material-specific self-organization in aqueous media. Here, we introduce a strategy that integrates a synthetic optically-responsive motif with a materials-binding peptide to enable remote actuation. Specifically, we linked a photoswitchable azobenzene moiety to either terminus of a Au-binding peptide. We employed these hybrid molecules as capping agents for synthesis of Au nanoparticles. Integrated experiments and molecular simulations showed that the hybrid molecules maintained both of their functions, i.e. binding to Au and optically-triggered reconfiguration. The azobenzene unit was optically switched reversibly between trans and cis states while adsorbed on the particle surface. Upon switching, the conformation of the peptide component of the molecule also changed. This highlights the interplay between the surface adsorption and conformational switching that will be pivotal to the creation of actuatable nanoparticle bio-interfaces, and paves the way toward multifunctional peptide hybrids that can produce stimuli responsive nanoassemblies.Bio-molecular non-covalent interactions provide a powerful platform for material-specific self-organization in aqueous media. Here, we introduce a strategy that integrates a synthetic optically-responsive motif with a materials-binding peptide to enable remote actuation. Specifically, we linked a photoswitchable azobenzene moiety to either terminus of a Au-binding peptide. We employed these hybrid molecules as capping agents for synthesis of Au nanoparticles. Integrated experiments and molecular simulations showed that the hybrid molecules maintained both of their functions, i.e. binding to Au and optically-triggered reconfiguration. The azobenzene unit was optically switched reversibly between trans and cis states while adsorbed on the particle surface. Upon switching, the conformation of the peptide component of the molecule also changed. This highlights the interplay between the surface adsorption and conformational switching that will be pivotal to the creation of actuatable nanoparticle bio-interfaces, and paves the way toward multifunctional peptide hybrids that can produce stimuli responsive nanoassemblies. Electronic supplementary information (ESI) available: Additional modeling analysis, QCM analysis, UV-vis and CD spectroscopy data. See DOI: 10.1039/C5NR02311D

Three dimensional graphene based materials: Synthesis and applications from energy storage and conversion to electrochemical sensor and environmental remediation.

PubMed

Wang, Hou; Yuan, Xingzhong; Zeng, Guangming; Wu, Yan; Liu, Yang; Jiang, Qian; Gu, Shansi

2015-07-01

With superior electrical/thermal conductivities and mechanical properties, two dimensional (2D) graphene has become one of the most intensively explored carbon allotropes in materials science. To exploit the inherent properties fully, 2D graphene sheets are often fabricated or assembled into functional architectures (e.g. hydrogels, aerogels) with desired three dimensional (3D) interconnected porous microstructures. The 3D graphene based materials show many excellent characteristics including increased active material per projected area, accessible mass transport or storage, electro/thermo conductivity, chemical/electrochemical stability and flexibility. It has paved the way for practical requirements in electronics, adsorption as well as catalysis related system. This review shows an extensive overview of the main principles and the recent synthetic technologies about fabricating various innovative 3D graphene based materials. Subsequently, recent progresses in electrochemical energy devices (lithium/lithium ion batteries, supercapacitors, fuel cells and solar cells) and hydrogen energy generation/storage are explicitly discussed. The up to date advances for pollutants detection and environmental remediation are also reviewed. Finally, challenges and outlooks in materials development for energy and environment are suggested. Copyright © 2015 Elsevier B.V. All rights reserved.

Dual-mode operation of 2D material-base hot electron transistors

PubMed Central

Lan, Yann-Wen; Torres, Jr., Carlos M.; Zhu, Xiaodan; Qasem, Hussam; Adleman, James R.; Lerner, Mitchell B.; Tsai, Shin-Hung; Shi, Yumeng; Li, Lain-Jong; Yeh, Wen-Kuan; Wang, Kang L.

2016-01-01

Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (VCB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.g. with either graphene or MoS2 in the base region) with the application of a negative collector-base potential (VCB < 0). That is, our 2D material-base hot electron transistors can operate in either a hot-electron or a reverse-current dominating mode depending upon the particular polarity of VCB. Furthermore, these devices operate at room temperature and their current gains can be dynamically tuned by varying VCB. We anticipate our multi-functional dual-mode transistors will pave the way towards the realization of novel flexible 2D material-based high-density and low-energy hot-carrier electronic applications. PMID:27581550

Dual-mode operation of 2D material-base hot electron transistors.

PubMed

Lan, Yann-Wen; Torres, Carlos M; Zhu, Xiaodan; Qasem, Hussam; Adleman, James R; Lerner, Mitchell B; Tsai, Shin-Hung; Shi, Yumeng; Li, Lain-Jong; Yeh, Wen-Kuan; Wang, Kang L

2016-09-01

Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (VCB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.g. with either graphene or MoS2 in the base region) with the application of a negative collector-base potential (VCB < 0). That is, our 2D material-base hot electron transistors can operate in either a hot-electron or a reverse-current dominating mode depending upon the particular polarity of VCB. Furthermore, these devices operate at room temperature and their current gains can be dynamically tuned by varying VCB. We anticipate our multi-functional dual-mode transistors will pave the way towards the realization of novel flexible 2D material-based high-density and low-energy hot-carrier electronic applications.

jsc2018m000274_Alpha-Space-Small-Business-Makes-Big-Strides_MP4

NASA Image and Video Library

2018-03-30

The path to discovery and exploration is paved with determination, innovation, and most of all, big ideas. The International Space Station is home to many of those ideas and creating new ways for small businesses, entrepreneurs and researchers to test their science and technology in space every day.Formed in 2015 in response to the need for a commercial payload that would be available to private companies aboard the space station, Alpha Space is a woman- and minority-owned small business responsible for developing the Materials International Space Station Experiment Flight Facility (MISSE-FF).

A class of invisible inhomogeneous media and the control of electromagnetic waves

NASA Astrophysics Data System (ADS)

Vial, B.; Liu, Y.; Horsley, S. A. R.; Philbin, T. G.; Hao, Y.

2016-12-01

We propose a general method to arbitrarily manipulate an electromagnetic wave propagating in a two-dimensional medium, without introducing any scattering. This leads to a whole class of isotropic spatially varying permittivity and permeability profiles that are invisible while shaping the field magnitude and/or phase. In addition, we propose a metamaterial structure working in the infrared that demonstrates deep subwavelength control of the electric field amplitude and strong reduction of the scattering. This work offers an alternative strategy to achieve invisibility with isotropic materials and paves the way for tailoring the propagation of light at the nanoscale.

Biomimetic microstructures for photonic and fluidic synergies

NASA Astrophysics Data System (ADS)

Vasileiou, Maria; Mpatzaka, Theodora; Alexandropoulos, Dimitris; Vainos, Nikolaos A.

2017-08-01

Nature-inspired micro- and nano-structures offer a unique platform for the development of novel synergetic systems combining photonic and microfluidic functionalities. In this context, we examine the paradigm of butterfly Vanessa cardui and develop artificial diffractive microstructures inspired by its natural designs. Softlithographic and nanoimprint protocols are developed to replicate surfaces of natural specimens. Further to their optical behavior, interphases tailored by such microstructures exhibit enhanced hydrophobic properties, as compared to their planar counterparts made of the same materials. Such synergies exploited by new design approaches pave the way to prospective optofluidic, lab-on-chip and sensing applications.

Differentiation between Staphylococcus aureus and Staphylococcus epidermidis strains using Raman spectroscopy.

PubMed

Rebrošová, Katarína; Šiler, Martin; Samek, Ota; Růžička, Filip; Bernatová, Silvie; Ježek, Jan; Zemánek, Pavel; Holá, Veronika

2017-08-01

Raman spectroscopy is an analytical method with a broad range of applications across multiple scientific fields. We report on a possibility to differentiate between two important Gram-positive species commonly found in clinical material - Staphylococcus aureus and Staphylococcus epidermidis - using this rapid noninvasive technique. For this, we tested 87 strains, 41 of S. aureus and 46 of S. epidermidis, directly from colonies grown on a Mueller-Hinton agar plate using Raman spectroscopy. The method paves a way for separation of these two species even on high number of samples and therefore, it can be potentially used in clinical diagnostics.

Laboratory testing of precast paving notch system.

DOT National Transportation Integrated Search

2008-02-01

Bridge approach pavement settlement and the resulting formation of bumps at the end : of bridges is a recurring problem on a number of Iowa bridges. One of the contributing : factors in this settlement is failure of the bridge paving notch. A p...

Effect on asphalt quality due to nighttime construction : final report.

DOT National Transportation Integrated Search

2017-06-01

The objectives of this project were to identify and analyze the nighttime paving traffic control standards in other states and compare the effects of daytime vs. nighttime paving on quality, safety, costs, and construction time. Surveys of various De...

Work plan for special design features and crack sealing maintenance.

DOT National Transportation Integrated Search

2013-09-01

The Alaska DOT&PF wants to construct and maintain asphalt concrete (AC) paved highways in a way that minimizes roadway lifecycle costs while preserving acceptable : performance. Thermal cracking is a natural feature of most paved Alaska roadways that...

Phase I: Evaluation of Low Flexural Strength for Northern Nevada Concrete Paving Mixtures

DOT National Transportation Integrated Search

2017-07-01

Production paving grade concrete in Northern Nevada having acceptable strength is universally acknowledged to be difficult; however understanding why this is true remains elusive. Current practice is to meet flexural strength requirements by using mi...

28. DOWNSTREAM VIEW OF ROCK PAVING OPERATIONS ON LEFT BANK ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

28. DOWNSTREAM VIEW OF ROCK PAVING OPERATIONS ON LEFT BANK OF OUTLET CHANNEL.... Volume XVI, No. 18, September 29, 1939. - Prado Dam, Outlet Works, Santa Ana River near junction of State Highways 71 & 91, Corona, Riverside County, CA

Assessment of tri-dyne precast concrete panels.

DOT National Transportation Integrated Search

2008-01-01

Tri-Dyne Industries has developed precast concrete paving slabs (PCPS) that connect using tongue and groove joints and overlap joints, as shown in Figure 1 (1). This proprietary system is referred to as the Pro-Active Paving SystemTM and consis...

Assessment of burrowing mammal impacts on paved highways in Montana.

DOT National Transportation Integrated Search

2010-12-01

The burrowing behavior of some rodents, insectivores, and mustelids has the potential to cause : damage to paved roads or exacerbate existing deterioration. The main objective of this project : was to characterize the nature and extent of burrowing m...

Keep the Rain Where It Belongs with Porous Pavement.

ERIC Educational Resources Information Center

American School and University, 1979

1979-01-01

Paved roads and parking lots have contributed to present and projected shortages of fresh water as well as to problems of flash floods. The utilization of porous asphalt paving can help prevent decreasing the reserves of ground water. (Author/MLF)

Infrared thermography-driven flaw detection and evaluation of hot mix asphalt pavements.

DOT National Transportation Integrated Search

2010-01-01

This research was conducted to study more realistic explanations of how variables are created and : dealt with during hot mix asphalt (HMA) paving construction. Several paving projects across the : state of Nebraska have been visited where sensory de...

EVALUATION OF EMISSIONS FROM PAVING ASPHALTS

EPA Science Inventory

The report provides data from pilot-scale measurements of the emissions of specific air pollutants from paving asphalt both with and without recycled crumb rubber additives. The methods used in this work measured emissions from a static layer of asphalt maintained for several hou...

Long-term field monitoring of paving fabric interlayer systems to reduce reflective cracking.

DOT National Transportation Integrated Search

2016-06-01

The formation of reflective cracking of pavement overlays has confronted highway engineers for many years. Stress-relieving interlayers, such as paving fabrics, have been used in an attempt to reduce or delay reflective cracking. The primary objectiv...

Improved rice method for determining theoretical maximum density of asphalt paving mixtures

DOT National Transportation Integrated Search

1992-05-01

Rice method (ASTM D2041 ) is used for determining the theoretical maximum specific gravity of asphalt paving mixtures which is one of the main test parameters used for mix design and construction quality control. The repeatability and reproducibility...

43. CAPE COD AIR STATION PAVE PAWS FACILITY WITH ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

43. CAPE COD AIR STATION PAVE PAWS FACILITY - WITH BUILDING METAL SIDING BEING APPLIED ON "C" FACE (RIGHT) AND "B" FACE BEING PREPARED FOR INSTALLATION. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

Construction of a thin-bonded Portland cement concrete overlay using accelerated paving techniques.

DOT National Transportation Integrated Search

1992-01-01

The report describes the Virginia Department of Transportations' first modern experience with the construction of thin-bonded Portland cement concrete overlays of existing concrete pavements and with the fast track mode of rigid paving. The study was...

49 CFR 571.224 - Standard No. 224; Rear impact protection.

Code of Federal Regulations, 2010 CFR

2010-10-01

... trailers, pulpwood trailers, road construction controlled horizontal discharge trailers, special purpose... latches are excluded from the determination of the rearmost point. Road construction controlled horizontal... machine or paving equipment for road construction and paving operations. Rounded corner means a guard's...

PAVE: program for assembling and viewing ESTs.

PubMed

Soderlund, Carol; Johnson, Eric; Bomhoff, Matthew; Descour, Anne

2009-08-26

New sequencing technologies are rapidly emerging. Many laboratories are simultaneously working with the traditional Sanger ESTs and experimenting with ESTs generated by the 454 Life Science sequencers. Though Sanger ESTs have been used to generate contigs for many years, no program takes full advantage of the 5' and 3' mate-pair information, hence, many tentative transcripts are assembled into two separate contigs. The new 454 technology has the benefit of high-throughput expression profiling, but introduces time and space problems for assembling large contigs. The PAVE (Program for Assembling and Viewing ESTs) assembler takes advantage of the 5' and 3' mate-pair information by requiring that the mate-pairs be assembled into the same contig and joined by n's if the two sub-contigs do not overlap. It handles the depth of 454 data sets by "burying" similar ESTs during assembly, which retains the expression level information while circumventing time and space problems. PAVE uses MegaBLAST for the clustering step and CAP3 for assembly, however it assembles incrementally to enforce the mate-pair constraint, bury ESTs, and reduce incorrect joins and splits. The PAVE data management system uses a MySQL database to store multiple libraries of ESTs along with their metadata; the management system allows multiple assemblies with variations on libraries and parameters. Analysis routines provide standard annotation for the contigs including a measure of differentially expressed genes across the libraries. A Java viewer program is provided for display and analysis of the results. Our results clearly show the benefit of using the PAVE assembler to explicitly use mate-pair information and bury ESTs for large contigs. The PAVE assembler provides a software package for assembling Sanger and/or 454 ESTs. The assembly software, data management software, Java viewer and user's guide are freely available.

Direct mapping and characterization of dry etch damage-induced PN junction for long-wavelength HgCdTe infrared detector arrays.

PubMed

Li, Yantao; Hu, Weida; Ye, Zhenhua; Chen, Yiyu; Chen, Xiaoshuang; Lu, Wei

2017-04-01

Mercury cadmium telluride is the standard material to fabricate high-performance infrared focal plane array (FPA) detectors. However, etch-induced damage is a serious obstacle for realizing highly uniform and damage-free FPA detectors. In this Letter, the high signal-to-noise ratio and high spatial resolution scanning photocurrent microscopy (SPCM) is used to characterize the dry etch-induced inversion layer of vacancy-doped p-type Hg_1-xCd_xTe (x=0.22) material under different etching temperatures. It is found that the peak-to-peak magnitude of the SPCM profile decreases with a decrease in etching temperature, showing direct proof of controlling dry etch-induced type conversion. Our work paves the way toward seeking optimal etching processes in large-scale infrared FPAs.

Robotic Exploration of Moon and Mars: Thematic Education Approach

NASA Technical Reports Server (NTRS)

Allen, J S.; Tobola, K. W.; Lowes, L. L.; Betrue, R.

2008-01-01

Safe, sustained, affordable human and robotic exploration of the Moon, Mars, and beyond is a major NASA goal. Robotic exploration of the Moon and Mars will help pave the way for an expanded human presence in our solar system. To help share the robotic exploration role in the Vision for Space Exploration with classrooms, informal education groups, and the public, our team researched and consolidated the thematic story components and associated education activities into a useful education materials set for educators. We developed the set of materials for a workshop combining NASA Science Mission Directorate and Exploration Systems Mission Directorate engineering, science, and technology to train informal educators on education activities that support the robotic exploration themes. A major focus is on the use of robotic spacecraft and instruments to explore and prepare for the human exploration of the Moon and Mars.

Subatomic deformation driven by vertical piezoelectricity from CdS ultrathin films.

PubMed

Wang, Xuewen; He, Xuexia; Zhu, Hongfei; Sun, Linfeng; Fu, Wei; Wang, Xingli; Hoong, Lai Chee; Wang, Hong; Zeng, Qingsheng; Zhao, Wu; Wei, Jun; Jin, Zhong; Shen, Zexiang; Liu, Jie; Zhang, Ting; Liu, Zheng

2016-07-01

Driven by the development of high-performance piezoelectric materials, actuators become an important tool for positioning objects with high accuracy down to nanometer scale, and have been used for a wide variety of equipment, such as atomic force microscopy and scanning tunneling microscopy. However, positioning at the subatomic scale is still a great challenge. Ultrathin piezoelectric materials may pave the way to positioning an object with extreme precision. Using ultrathin CdS thin films, we demonstrate vertical piezoelectricity in atomic scale (three to five space lattices). With an in situ scanning Kelvin force microscopy and single and dual ac resonance tracking piezoelectric force microscopy, the vertical piezoelectric coefficient (d 33) up to 33 pm·V(-1) was determined for the CdS ultrathin films. These findings shed light on the design of next-generation sensors and microelectromechanical devices.

Nanometric holograms based on a topological insulator material.

PubMed

Yue, Zengji; Xue, Gaolei; Liu, Juan; Wang, Yongtian; Gu, Min

2017-05-18

Holography has extremely extensive applications in conventional optical instruments spanning optical microscopy and imaging, three-dimensional displays and metrology. To integrate holography with modern low-dimensional electronic devices, holograms need to be thinned to a nanometric scale. However, to keep a pronounced phase shift modulation, the thickness of holograms has been generally limited to the optical wavelength scale, which hinders their integration with ultrathin electronic devices. Here, we break this limit and achieve 60 nm holograms using a topological insulator material. We discover that nanometric topological insulator thin films act as an intrinsic optical resonant cavity due to the unequal refractive indices in their metallic surfaces and bulk. The resonant cavity leads to enhancement of phase shifts and thus the holographic imaging. Our work paves a way towards integrating holography with flat electronic devices for optical imaging, data storage and information security.

Statistical quality control and quality assurance evaluation of structural & paving concrete : phase I final report.

DOT National Transportation Integrated Search

2001-08-01

This report discusses the variability associated with the production, construction, and testing of structural and paving concrete. The study evaluated data from over 900 projects constructed between 1992 and 1999, representing over 25,000 lots. The d...

14 CFR 139.305 - Paved areas.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Paved areas. 139.305 Section 139.305 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR CARRIERS... paragraph (b) of this section, mud, dirt, sand, loose aggregate, debris, foreign objects, rubber deposits...

14 CFR 139.305 - Paved areas.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Paved areas. 139.305 Section 139.305 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR CARRIERS... paragraph (b) of this section, mud, dirt, sand, loose aggregate, debris, foreign objects, rubber deposits...

Non-invasive imaging and assessment of active karst features in proximity to paved roadways.

DOT National Transportation Integrated Search

2014-02-01

In an effort to better understand and define the lateral and vertical extent of active karst features in immediate proximity to paved : MoDOT roadways in Springfield Missouri, MS&T will acquire electrical resistivity tomography (ERT) data. The intent...

View of the PAVE PAWS radar from approach along Spencer ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of the PAVE PAWS radar from approach along Spencer Paul Road, looking northwest - Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

Evaluation of safety effectiveness of composite shoulders, wide unpaved shoulders, and wide paved shoulders in Kansas.

DOT National Transportation Integrated Search

2013-03-01

Incremental increases in paved shoulder widths have been studied and are shown in the Highway Safety Manual. While : each incremental increase in shoulder width is beneficial, there is evidence that suggests the relationship between safety : improvem...

Development of Guidelines for Reduction of Temperature Differential Damage (TDD) for Hot Mix Asphalt Pavement Projects in Connecticut

DOT National Transportation Integrated Search

1999-11-01

Connecticut Department of Transportation personnel used an infrared camera to observe thermal segregation of hot mix asphalt during pavement construction. Several sites were selected for study from ongoing paving projects. During paving operations, t...

14 CFR 139.305 - Paved areas.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Paved areas. 139.305 Section 139.305 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR CARRIERS... paragraph (b) of this section, mud, dirt, sand, loose aggregate, debris, foreign objects, rubber deposits...

14 CFR 139.305 - Paved areas.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Paved areas. 139.305 Section 139.305 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR CARRIERS... paragraph (b) of this section, mud, dirt, sand, loose aggregate, debris, foreign objects, rubber deposits...

14 CFR 139.305 - Paved areas.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Paved areas. 139.305 Section 139.305 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR CARRIERS... paragraph (b) of this section, mud, dirt, sand, loose aggregate, debris, foreign objects, rubber deposits...

Self-consolidating concrete, applications for slip-form paving : phase II.

DOT National Transportation Integrated Search

2011-05-01

The goal of the project was to develop a new type of self-consolidating concrete (SCC) for slip-form paving to simplify construction and make smoother pavements. Developing the new SCC involved two phases: a feasibility study (Phase I sponsored by TP...

42. CAPE COD AIR STATION PAVE PAWS FACILITY SHOWING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

42. CAPE COD AIR STATION PAVE PAWS FACILITY - SHOWING BUILDING "RED IRON" STEEL STRUCTURE AT 46T DAY OF STEEL CONSTRUCTION. "BUILDING TOPPED OFF, 7 JULY, 1974. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

Feasibility study of two-lift concrete paving : technical report.

DOT National Transportation Integrated Search

2014-04-01

Two-lift concrete paving (2LCP) involves placing two layers of concrete (wet-on-wet) instead of a single : homogeneous layer, as is typically done in the United States. 2LCP offers the opportunity to optimize the use of local : aggregates, recycled m...

Paving asphalt products exhibit a lack of carcinogenic and mutagenic activity.

PubMed

Goyak, Katy O; McKee, Richard H; Minsavage, Gary D; McGowan, Claude; Daughtrey, Wayne C; Freeman, James J

2011-10-01

A paving asphalt and a vacuum residuum (derived from crude oil by atmospheric and subsequent vacuum distillation and used as a blend stock for asphalt) were tested in skin carcinogenesis assays in mice and in optimized Ames assays for mutagenic activity. In the skin cancer tests, each substance was applied twice weekly for 104 weeks to the clipped backs of groups of 50 male C3H mice. Neither the paving asphalt nor the vacuum residuum (30% weight/volume and 75% weight/weight in US Pharmacopeia mineral oil, respectively) produced any tumors. The positive control benzo[a]pyrene (0.05% w/v in toluene) induced tumors in 46 of 50 mice, demonstrating the effectiveness of the test method. Salmonella typhimurium tester strain TA98 was used in the optimized Ames assay to evaluate mutagenic potential. Dimethylsulfoxide (DMSO) extractions of the substances were not mutagenic when tested up to toxic limits. Thus, under the conditions of these studies, neither the paving asphalt nor the vacuum residuum was carcinogenic or mutagenic.

Introduction

NASA Astrophysics Data System (ADS)

Starosvetsky, Yuli; Jayaprakash, K. R.; Hasan, Md. Arif; Vakakis, Alexander F.

The study of mechanics of granular media dates back to the era of Coulomb. He was the first to postulate the yield condition for homogeneous solids and also conditions for failure in granular media [1-4]. In fact the ideal Coulomb material is the simplest granular material model wherein the shear stress along a plane is linearly proportional to the normal stress on that plane. This can be considered analogous to the Coulomb friction model in cohesion-free interfaces between solids. Initial research in this domain focused mainly on the statics of granular materials from a soil mechanics perspective. However, as the applications of granular materials broadened, the objectives of different research communities contradicted. For example, in geophysics or soil mechanics the objective is to regard granular media with properties of a solid in order to take considerable loads without yielding; on the other hand, in food grain or pharmaceutical industries the granular media is considered as fluids and their rheological properties are of interest. In fact granular media can exhibit both of these behaviors (and also the properties of a gas), and such unique features pave the way for their broad range applications...

Superior pseudocapacitive behavior of confined lignin nanocrystals for renewable energy-storage materials.

PubMed

Kim, Sung-Kon; Kim, Yun Ki; Lee, Hyunjoo; Lee, Sang Bok; Park, Ho Seok

2014-04-01

Strong demand for high-performance energy-storage devices has currently motivated the development of emerging capacitive materials that can resolve their critical challenge (i.e., low energy density) and that are renewable and inexpensive energy-storage materials from both environmental and economic viewpoints. Herein, the pseudocapacitive behavior of lignin nanocrystals confined on reduced graphene oxides (RGOs) used for renewable energy-storage materials is demonstrated. The excellent capacitive characteristics of the renewable hybrid electrodes were achieved by synergizing the fast and reversible redox charge transfer of surface-confined quinone and the interplay with electron-conducting RGOs. Accordingly, pseudocapacitors with remarkable rate and cyclic performances (~96 % retention after 3000 cycles) showed a maximum capacitance of 432 F g(-1), which was close to the theoretical capacitance of 482 F g(-1) and sixfold higher than that of RGO (93 F g(-1)). The chemical strategy delineated herein paves the way to develop advanced renewable electrodes for energy-storage applications and understand the redox chemistry of electroactive biomaterials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Air Purification Pavement Surface Coating by Atmospheric Pressure Cold Plasma

NASA Astrophysics Data System (ADS)

Westergreen, Joe; Pedrow, Patrick; Shen, Shihui; Jobson, Bertram

2011-10-01

This study develops an atmospheric pressure cold plasma (APCP) reactor to produce activated radicals from precursor molecules, and to immobilize nano titanium dioxide (TiO2) powder to substrate pavement materials. TiO2 has photocatalytic properties and under UV light can be used to oxidize and remove volatile organic compounds (VOCs) and nitrogen oxides (NOx) from the atmosphere. Although TiO2 treated paving materials have great potential to improve air quality, current techniques to adhere TiO2 to substrate materials are either not durable or reduce direct contact of TiO2 with UV light, reducing the photocatalytic effect. To solve this technical difficulty, this study introduces APCP techniques to transportation engineering to coat TiO2 to pavement. Preliminary results are promising and show that TiO2 can be incorporated successfully into an APCP environment and can be immobilized at the surface of the asphalt substrate. The TiO2 coated material with APCP shows the ability to reduce nitrogen oxides when exposed to UV light in an environmental chamber. The plasma reactor utilizes high voltage streamers as the plasma source.

Modified Powder-in-Tube Technique Based on the Consolidation Processing of Powder Materials for Fabricating Specialty Optical Fibers

PubMed Central

Auguste, Jean-Louis; Humbert, Georges; Leparmentier, Stéphanie; Kudinova, Maryna; Martin, Pierre-Olivier; Delaizir, Gaëlle; Schuster, Kay; Litzkendorf, Doris

2014-01-01

The objective of this paper is to demonstrate the interest of a consolidation process associated with the powder-in-tube technique in order to fabricate a long length of specialty optical fibers. This so-called Modified Powder-in-Tube (MPIT) process is very flexible and paves the way to multimaterial optical fiber fabrications with different core and cladding glassy materials. Another feature of this technique lies in the sintering of the preform under reducing or oxidizing atmosphere. The fabrication of such optical fibers implies different constraints that we have to deal with, namely chemical species diffusion or mechanical stress due to the mismatches between thermal expansion coefficients and working temperatures of the fiber materials. This paper focuses on preliminary results obtained with a lanthano-aluminosilicate glass used as the core material for the fabrication of all-glass fibers or specialty Photonic Crystal Fibers (PCFs). To complete the panel of original microstructures now available by the MPIT technique, we also present several optical fibers in which metallic particles or microwires are included into a silica-based matrix. PMID:28788176

Si-doping bone composite based on protein template-mediated assembly for enhancing bone regeneration

NASA Astrophysics Data System (ADS)

Yang, Qin; Du, Yingying; Wang, Yifan; Wang, Zhiying; Ma, Jun; Wang, Jianglin; Zhang, Shengmin

2017-06-01

Bio-inspired hybrid materials that contain organic and inorganic networks interpenetration at the molecular level have been a particular focus of interest on designing novel nanoscale composites. Here we firstly synthesized a series of hybrid bone composites, silicon-hydroxyapatites/silk fibroin/collagen, based on a specific molecular assembled strategy. Results of material characterization confirmed that silicate had been successfully doped into nano-hydroxyapatite lattice. In vitro evaluation at the cellular level clearly showed that these Si-doped composites were capable of promoting the adhesion and proliferation of rat mesenchymal stem cells (rMSCs), extremely enhancing osteoblastic differentiation of rMSCs compared with silicon-free composite. More interestingly, we found there was a critical point of silicon content in the composition on regulating multiple cell behaviors. In vivo animal evaluation further demonstrated that Si-doped composites enabled to significantly improve the repair of cranial bone defect. Consequently, our current work not only suggests fabricating a potential bone repair materials by integrating element-doping and molecular assembled strategy in one system, but also paves a new way for constructing multi-functional composite materials in the future.

Realizing p-Type MoS2 with Enhanced Thermoelectric Performance by Embedding VMo2S4 Nanoinclusions.

PubMed

Kong, Shuang; Wu, Tianmin; Zhuang, Wei; Jiang, Peng; Bao, Xinhe

2018-01-18

Two-dimensional transition-metal dichalcogenide semiconductors (TMDCs) such as MoS 2 are attracting increasing interest as thermoelectric materials owing to their abundance, nontoxicity, and promising performance. Recently, we have successfully developed n-type MoS 2 thermoelectric material via oxygen doping. Nevertheless, an efficient thermoelectric module requires both n-type and p-type materials with similar compatibility factors. Here, we present a facile approach to obtain a p-type MoS 2 thermoelectric material with a maximum figure of merit of 0.18 through the introduction of VMo 2 S 4 as a second phase by vanadium doping. VMo 2 S 4 nanoinclusions, confirmed by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) measurements, not only improve the electrical conductivity by simultaneously increasing the carrier concentration and the mobility but also result in the reduction of lattice thermal conductivity by enhancing the interface phonon scattering. Our studies not only shed new light toward improving thermoelectric performance of TMDCs by a facile elemental doping strategy but also pave the way toward thermoelectric devices based on TMDCs.

Enamel Regeneration - Current Progress and Challenges

PubMed Central

Baswaraj; H.K, Navin; K.B, Prasanna

2014-01-01

Dental Enamel is the outermost covering of teeth. It is hardest mineralized tissue present in the human body. Enamel faces the challenge of maintaining its integrity in a constant demineralization and remineralization within the oral environment and it is vulnerable to wear, damage, and decay. It cannot regenerate itself, because it is formed by a layer of cells that are lost after the tooth eruption. Conventional treatment relies on synthetic materials to restore lost enamel that cannot mimic natural enamel. With advances in material science and understanding of basic principles of organic matrix mediated mineralization paves a way for formation of synthetic enamel. The knowledge of enamel formation and understanding of protein interactions and their gene products function along with the isolation of postnatal stem cells from various sources in the oral cavity, and the development of smart materials for cell and growth factor delivery, makes possibility for biological based enamel regeneration. This article will review the recent endeavor on biomimetic synthesis and cell based strategies for enamel regeneration. PMID:25386548

Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

DOE PAGES

Zhang, Yanwen; Stocks, George Malcolm; Jin, Ke; ...

2015-10-28

A long-standing objective in materials research is to understand how energy is dissipated in both the electronic and atomic subsystems in irradiated materials, and how related non-equilibrium processes may affect defect dynamics and microstructure evolution. Here we show that alloy complexity in concentrated solid solution alloys having both an increasing number of principal elements and altered concentrations of specific elements can lead to substantial reduction in the electron mean free path and thermal conductivity, which has a significant impact on energy dissipation and consequentially on defect evolution during ion irradiation. Enhanced radiation resistance with increasing complexity from pure nickel tomore » binary and to more complex quaternary solid solutions is observed under ion irradiation up to an average damage level of 1 displacement per atom. Understanding how materials properties can be tailored by alloy complexity and their influence on defect dynamics may pave the way for new principles for the design of radiation tolerant structural alloys.« less

Atomic species identification at the (101) anatase surface by simultaneous scanning tunnelling and atomic force microscopy

PubMed Central

Stetsovych, Oleksandr; Todorović, Milica; Shimizu, Tomoko K.; Moreno, César; Ryan, James William; León, Carmen Pérez; Sagisaka, Keisuke; Palomares, Emilio; Matolín, Vladimír; Fujita, Daisuke; Perez, Ruben; Custance, Oscar

2015-01-01

Anatase is a pivotal material in devices for energy-harvesting applications and catalysis. Methods for the accurate characterization of this reducible oxide at the atomic scale are critical in the exploration of outstanding properties for technological developments. Here we combine atomic force microscopy (AFM) and scanning tunnelling microscopy (STM), supported by first-principles calculations, for the simultaneous imaging and unambiguous identification of atomic species at the (101) anatase surface. We demonstrate that dynamic AFM-STM operation allows atomic resolution imaging within the material's band gap. Based on key distinguishing features extracted from calculations and experiments, we identify candidates for the most common surface defects. Our results pave the way for the understanding of surface processes, like adsorption of metal dopants and photoactive molecules, that are fundamental for the catalytic and photovoltaic applications of anatase, and demonstrate the potential of dynamic AFM-STM for the characterization of wide band gap materials. PMID:26118408

Thermoelectric Signal Enhancement by Reconciling the Spin Seebeck and Anomalous Nernst Effects in Ferromagnet/Non-magnet Multilayers

PubMed Central

Lee, Kyeong-Dong; Kim, Dong-Jun; Yeon Lee, Hae; Kim, Seung-Hyun; Lee, Jong-Hyun; Lee, Kyung-Min; Jeong, Jong-Ryul; Lee, Ki-Suk; Song, Hyon-Seok; Sohn, Jeong-Woo; Shin, Sung-Chul; Park, Byong-Guk

2015-01-01

The utilization of ferromagnetic (FM) materials in thermoelectric devices allows one to have a simpler structure and/or independent control of electric and thermal conductivities, which may further remove obstacles for this technology to be realized. The thermoelectricity in FM/non-magnet (NM) heterostructures using an optical heating source is studied as a function of NM materials and a number of multilayers. It is observed that the overall thermoelectric signal in those structures which is contributed by spin Seebeck effect and anomalous Nernst effect (ANE) is enhanced by a proper selection of NM materials with a spin Hall angle that matches to the sign of the ANE. Moreover, by an increase of the number of multilayer, the thermoelectric voltage is enlarged further and the device resistance is reduced, simultaneously. The experimental observation of the improvement of thermoelectric properties may pave the way for the realization of magnetic-(or spin-) based thermoelectric devices. PMID:26020492

Chemical Functionalization of Polysaccharides-Towards Biocompatible Hydrogels for Biomedical Applications.

PubMed

Kirschning, Andreas; Dibbert, Nick; Dräger, Gerald

2018-01-26

Hydrogels have emerged as a highly interdisciplinary topic as they play a significant role for a vast number of applications. They have been studied extensively as materials for contact lenses, wound dressing and as filler material in soft-tissue augmentation, in which classical polymer backbones such as hydroxyethylmethacrylate (HEMA) are typically employed. More recently, polysaccharides have received attention, particularly in the fields of regenerative medicine and tissue engineering, as ideal candidate materials for artificial extracellular matrices (ECM). The polysaccharides of choice are dextran, alginate, chitosan, hyaluronic acid and pullulan and in order to obtain suitable hydrogels from these polysaccharides, controlled chemical functionalization is of critical importance. This short review summarizes recent developments in the chemical derivatization of polysaccharides to pave the way for crosslinking and to decorate individual polysaccharide chains with bioactive ligands. The report covers convergent and divergent protocols for crosslinking, as well strategies for bisfunctionalization of polysaccharides. Additionally, information on biological properties and biomedical applications are covered. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-performance shape-engineerable thermoelectric painting

PubMed Central

Park, Sung Hoon; Jo, Seungki; Kwon, Beomjin; Kim, Fredrick; Ban, Hyeong Woo; Lee, Ji Eun; Gu, Da Hwi; Lee, Se Hwa; Hwang, Younghun; Kim, Jin-Sang; Hyun, Dow-Bin; Lee, Sukbin; Choi, Kyoung Jin; Jo, Wook; Son, Jae Sung

2016-01-01

Output power of thermoelectric generators depends on device engineering minimizing heat loss as well as inherent material properties. However, the device engineering has been largely neglected due to the limited flat or angular shape of devices. Considering that the surface of most heat sources where these planar devices are attached is curved, a considerable amount of heat loss is inevitable. To address this issue, here, we present the shape-engineerable thermoelectric painting, geometrically compatible to surfaces of any shape. We prepared Bi2Te3-based inorganic paints using the molecular Sb2Te3 chalcogenidometalate as a sintering aid for thermoelectric particles, with ZT values of 0.67 for n-type and 1.21 for p-type painted materials that compete the bulk values. Devices directly brush-painted onto curved surfaces produced the high output power of 4.0 mW cm−2. This approach paves the way to designing materials and devices that can be easily transferred to other applications. PMID:27834369

Thermoelectric Signal Enhancement by Reconciling the Spin Seebeck and Anomalous Nernst Effects in Ferromagnet/Non-magnet Multilayers.

PubMed

Lee, Kyeong-Dong; Kim, Dong-Jun; Yeon Lee, Hae; Kim, Seung-Hyun; Lee, Jong-Hyun; Lee, Kyung-Min; Jeong, Jong-Ryul; Lee, Ki-Suk; Song, Hyon-Seok; Sohn, Jeong-Woo; Shin, Sung-Chul; Park, Byong-Guk

2015-05-28

The utilization of ferromagnetic (FM) materials in thermoelectric devices allows one to have a simpler structure and/or independent control of electric and thermal conductivities, which may further remove obstacles for this technology to be realized. The thermoelectricity in FM/non-magnet (NM) heterostructures using an optical heating source is studied as a function of NM materials and a number of multilayers. It is observed that the overall thermoelectric signal in those structures which is contributed by spin Seebeck effect and anomalous Nernst effect (ANE) is enhanced by a proper selection of NM materials with a spin Hall angle that matches to the sign of the ANE. Moreover, by an increase of the number of multilayer, the thermoelectric voltage is enlarged further and the device resistance is reduced, simultaneously. The experimental observation of the improvement of thermoelectric properties may pave the way for the realization of magnetic-(or spin-) based thermoelectric devices.

Experimental investigation of basic oxygen furnace slag used as aggregate in asphalt mixture.

PubMed

Xue, Yongjie; Wu, Shaopeng; Hou, Haobo; Zha, Jin

2006-11-16

Chinese researchers have commenced a great deal of researches on the development of application fields of basic oxygen steel making furnace slag (BOF slag) for many years. Lots of new applications and properties have been found, but few of them in asphalt mixture of road construction engineering. This paper discussed the feasibility of BOF steel slag used as aggregate in asphalt pavement by two points of view including BOF steel slag's physical and micro-properties as well as steel slag asphalt materials and pavement performances. For the former part, this paper mainly concerned the mechanochemistry and physical changes of the steel slag and studied it by performing XRD, SEM, TG and mercury porosimeter analysis and testing method. In the second part, this paper intended to use BOF steel slag as raw material, and design steel slag SMA mixture. By using traditional rutting test, soak wheel track and modified Lottman test, the high temperature stability and water resistance ability were tested. Single axes compression test and indirect tensile test were performed to evaluate the low temperature crack resistance performance and fatigue characteristic. Simultaneously, by observing steel slag SMA pavement which was paved successfully. A follow-up study to evaluate the performance of the experimental pavement confirmed that the experimental pavement was comparable with conventional asphalt pavement, even superior to the later in some aspects. All of above test results and analysis had only one main purpose that this paper validated the opinion that using BOF slag in asphalt concrete is feasible. So this paper suggested that treated and tested steel slag should be used in a more extensive range, especially in asphalt mixture paving projects in such an abundant steel slag resource region.

Polymeric Endoaortic Paving (PEAP): Mechanical, Thermoforming, and Degradation Properties of Polycaprolactone/Polyurethane Blends for Cardiovascular Applications

PubMed Central

Ashton, John H.; Mertz, James A. M.; Harper, John L.; Slepian, Marvin J.; Mills, Joseph L.; McGrath, Dominic V.; Vande Geest, Jonathan P.

2010-01-01

Polymeric endoaortic paving (PEAP) is a process by which a polymer is endovascularly delivered and thermoformed to coat or “pave” the lumen of the aorta. This method may offer an improvement to conventional endoaortic therapy in allowing conformal graft application with reduced risk of endoleak and customization to complex patient geometries. Polycaprolactone (PCL)/polyurethane (PU) blends of various blend ratios were assessed as a potential material for PEAP by characterizing their mechanical, thermoforming, and degradation properties. Biaxial tension testing revealed that the blends' stiffness is similar to that of aortic tissue, is higher for blends with more PCL content, and may be affected by thermoforming and degradation. Tubes of blends were able to maintain a higher diameter increase after thermoforming at higher PCL content and higher heating temperatures; 50/50 blend tubes heated to 55°C were able to maintain 90% of the diameter increase applied. Delamination forces of the blends ranged from 41 to 235 N/m2. In a Pseudomonas lipase solution, the 50/50 blend had a 94% lower degradation rate than pure PCL, and the 10/90 blend exhibited no degradation. These results indicate that PEAP, consisting of a PCL/PU blend, may be useful in developing the next generation of endoaortic therapy. PMID:20832506

Utilization of recycled asphalt concrete with warm mix asphalt and cost-benefit analysis.

PubMed

Oner, Julide; Sengoz, Burak

2015-01-01

The asphalt paving industries are faced with two major problems. These two important challenges are generated with an increase in demand for environmentally friendly paving mixtures and the problem of rapidly rising raw materials. Recycling of reclaimed asphalt pavement (RAP) is a critical necessity to save precious aggregates and reduce the use of costly bitumen. Warm Mix Asphalt (WMA) technology provides not only the option of recycling asphalt pavement at a lower temperature than the temperature maintained in hot mixtures but also encourages the utilization of RAP and therefore saves energy and money. This paper describes the feasibility of utilizing three different WMA additives (organic, chemical and water containing) at recommended contents with different percentages of RAP. The mechanical properties and cost-benefit analysis of WMA containing RAP have been performed and compared with WMA without RAP. The results indicated that, 30%, 10% and 20% can be accepted as an optimum RAP addition related to organic, chemical and water containing additives respectively and organic additive with 30% RAP content has an appreciable increase in tensile strength over the control mix. It was also concluded that the RAP with WMA technology is the ability to reduce final cost compared to HMA and WMA mixtures.

Utilization of Recycled Asphalt Concrete with Warm Mix Asphalt and Cost-Benefit Analysis

PubMed Central

Oner, Julide; Sengoz, Burak

2015-01-01

The asphalt paving industries are faced with two major problems. These two important challenges are generated with an increase in demand for environmentally friendly paving mixtures and the problem of rapidly rising raw materials. Recycling of reclaimed asphalt pavement (RAP) is a critical necessity to save precious aggregates and reduce the use of costly bitumen. Warm Mix Asphalt (WMA) technology provides not only the option of recycling asphalt pavement at a lower temperature than the temperature maintained in hot mixtures but also encourages the utilization of RAP and therefore saves energy and money. This paper describes the feasibility of utilizing three different WMA additives (organic, chemical and water containing) at recommended contents with different percentages of RAP. The mechanical properties and cost-benefit analysis of WMA containing RAP have been performed and compared with WMA without RAP. The results indicated that, 30%, 10% and 20% can be accepted as an optimum RAP addition related to organic, chemical and water containing additives respectively and organic additive with 30% RAP content has an appreciable increase in tensile strength over the control mix. It was also concluded that the RAP with WMA technology is the ability to reduce final cost compared to HMA and WMA mixtures. PMID:25574851

Wall stress reduction in abdominal aortic aneurysms as a result of polymeric endoaortic paving.

PubMed

Ashton, John H; Ayyalasomayajula, Avinash; Simon, Bruce R; Vande Geest, Jonathan P

2011-06-01

Polymeric endoaortic paving (PEAP) may improve endovascular repair of abdominal aortic aneurysms (AAA) since it has the potential to treat patients with complex AAA geometries while reducing the incidence of migration and endoleak. Polycaprolactone (PCL)/polyurethane (PU) blends are proposed as PEAP materials due to their range of mechanical properties, thermoformability, and resistance to biodegradation. In this study, the reduction in AAA wall stress that can be achieved using PEAP was estimated and compared to that resulting from stent-grafts. This was accomplished by mechanically modeling the anisotropic response of PCL/PU blends and implementing these results into finite element model (FEM) simulations. We found that at the maximum diameter of the AAA, the 50/50 and 10/90 PCL/PU blends reduced wall stress by 99 and 98%, respectively, while a stent-graft reduced wall stress by 99%. Our results also show that wall stress reduction increases with increasing PEAP thickness and PCL content in the blend ratio. These results indicate that PEAP can reduce AAA wall stress as effectively as a stent-graft. As such, we propose that PEAP may provide an improved treatment alternative for AAA, since many of the limitations of stent-grafts have the potential to be solved using this approach.

Non-linear Mechanics of Three-dimensional Architected Materials; Design of Soft and Functional Systems and Structures

NASA Astrophysics Data System (ADS)

Babaee, Sahab

In the search for materials with new properties, there have been significant advances in recent years aimed at the construction of architected materials whose behavior is governed by structure, rather than composition. Through careful design of the material's architecture, new mechanical properties have been demonstrated, including negative Poisson's ratio, high stiffness to weight ratio and mechanical cloaking. However, most of the proposed architected materials (also known as mechanical metamaterials) have a unique structure that cannot be recon figured after fabrication, making them suitable only for a specific task. This thesis focuses on the design of architected materials that take advantage of the applied large deformation to enhance their functionality. Mechanical instabilities, which have been traditionally viewed as a failure mode with research focusing on how to avoid them, are exploited to achieve novel and tunable functionalities. In particular I demonstrate the design of mechanical metamaterials with tunable negative Poisson ratio, adaptive phononic band gaps, acoustic switches, and reconfigurable origami-inspired waveguides. Remarkably, due to large deformation capability and full reversibility of soft materials, the responses of the proposed designs are reversible, repeatable, and scale independent. The results presented here pave the way for the design of a new class of soft, active, adaptive, programmable and tunable structures and systems with unprecedented performance and improved functionalities.

Evaluation of safety effectiveness of composite shoulders, wide unpaved shoulders, and wide paved shoulders in Kansas : [technical summary].

DOT National Transportation Integrated Search

2013-03-01

Incremental increases in paved shoulder widths have been studied and are shown in the Highway Safety Manual (HSM). While each incremental increase in shoulder width is beneficial, there is evidence that suggests the relationship between safety improv...

Project 0-6749 : feasibility study of two-lift concrete paving : [project summary].

DOT National Transportation Integrated Search

2013-08-01

Two-lift concrete paving (2LCP) involves placing two layers of : concrete (wet-on-wet) instead of a single homogeneous layer, as is : typically done in the United States. 2LCP offers the opportunity to optimize the use of local aggregates and : recyc...

Best practices for the design, evaluation and quality control of high percentage RAP mixes.

DOT National Transportation Integrated Search

2015-12-01

Placing reclaimed asphalt pavement (RAP) back on the roadway is a common and popular technique in the paving industry. There are always challenges associated with this type of recycling, especially when the RAP content in the newly paved asphalt mix ...

CHARACTERIZATION OF MUD/DIRT CARRYOUT ONTO PAVED ROADS FROM CONSTRUCTION AND DEMOLITION ACTIVITIES

EPA Science Inventory

The report characterizes fugitive dust generated by vehicular traffic on paved streets and highways resulting from mud/dirt carryout from unpaved areas as a primary source of PM-10 (particles = or < 10 micrometers in aerodynamic diameter), and evaluates three technologies for eff...

Photoinduced Topological Phase Transitions in Topological Magnon Insulators.

PubMed

Owerre, S A

2018-03-13

Topological magnon insulators are the bosonic analogs of electronic topological insulators. They are manifested in magnetic materials with topologically nontrivial magnon bands as realized experimentally in a quasi-two-dimensional (quasi-2D) kagomé ferromagnet Cu(1-3, bdc), and they also possess protected magnon edge modes. These topological magnetic materials can transport heat as well as spin currents, hence they can be useful for spintronic applications. Moreover, as magnons are charge-neutral spin-1 bosonic quasiparticles with a magnetic dipole moment, topological magnon materials can also interact with electromagnetic fields through the Aharonov-Casher effect. In this report, we study photoinduced topological phase transitions in intrinsic topological magnon insulators in the kagomé ferromagnets. Using magnonic Floquet-Bloch theory, we show that by varying the light intensity, periodically driven intrinsic topological magnetic materials can be manipulated into different topological phases with different sign of the Berry curvatures and the thermal Hall conductivity. We further show that, under certain conditions, periodically driven gapped topological magnon insulators can also be tuned to synthetic gapless topological magnon semimetals with Dirac-Weyl magnon cones. We envision that this work will pave the way for interesting new potential practical applications in topological magnetic materials.

Nano- and microstructured materials for in vitro studies of the physiology of vascular cells

PubMed Central

Chen, Hao; Biela, Sarah A; Kaufmann, Dieter

2016-01-01

The extracellular environment of vascular cells in vivo is complex in its chemical composition, physical properties, and architecture. Consequently, it has been a great challenge to study vascular cell responses in vitro, either to understand their interaction with their native environment or to investigate their interaction with artificial structures such as implant surfaces. New procedures and techniques from materials science to fabricate bio-scaffolds and surfaces have enabled novel studies of vascular cell responses under well-defined, controllable culture conditions. These advancements are paving the way for a deeper understanding of vascular cell biology and materials–cell interaction. Here, we review previous work focusing on the interaction of vascular smooth muscle cells (SMCs) and endothelial cells (ECs) with materials having micro- and nanostructured surfaces. We summarize fabrication techniques for surface topographies, materials, geometries, biochemical functionalization, and mechanical properties of such materials. Furthermore, various studies on vascular cell behavior and their biological responses to micro- and nanostructured surfaces are reviewed. Emphasis is given to studies of cell morphology and motility, cell proliferation, the cytoskeleton and cell-matrix adhesions, and signal transduction pathways of vascular cells. We finalize with a short outlook on potential interesting future studies. PMID:28144512

Bladder cancer incidence and exposure to polycyclic aromatic hydrocarbons among asphalt pavers.

PubMed

Burstyn, Igor; Kromhout, Hans; Johansen, Christoffer; Langard, Sverre; Kauppinen, Timo; Shaham, Judith; Ferro, Gilles; Boffetta, Paolo

2007-08-01

To investigate the association between exposures to polycyclic aromatic hydrocarbons (PAH) that arises during asphalt paving, and risk of bladder cancer. 7298 men included in the historical cohort were first employed between 1913 and 1999 in companies applying asphalt in Denmark, Norway, Finland and Israel. The minimal duration of employment for inclusion in the cohort was two seasons of work. Occupational histories were extracted from personnel files. A follow-up for cancer incidence was conducted through national cancer registries. The authors estimated exposures to benzo(a)pyrene as a marker for 4-6 ring PAH. Exposures were reconstructed by using information about changes in asphalt paving technology in each company over time, the modelled relation between production characteristics and exposure levels, and job histories. Relative risks and associated 95% confidence intervals were estimated using Poisson regression. 48 bladder cancers among asphalt paving workers were detected; of these, 39 cases were exposed at least 15 years before the diagnosis. Cumulative exposure to PAH was not associated with the incidence of bladder cancer. The association with average exposure became stronger when 15-year lag was considered, revealing a twofold increase in relative bladder cancer risk in the two higher exposure categories. There was an indication of exposure-response association with lagged averaged exposure. Risk estimates were adjusted for age, country, duration of employment and calendar period, did not show heterogeneity among countries and did not materially change when re-estimated after excluding non-primary cancers from follow-up. Previously conducted sensitivity analysis indicates that confounding by cigarette smoking is an unlikely explanation for the observed exposure-response trends. The authors were unable to control for all possible sources of confounding and bias. The results do not allow conclusion on the presence or absence of a causal link between exposures to PAH and risk of bladder cancer among asphalt workers.

Bladder cancer incidence and exposure to polycyclic aromatic hydrocarbons among asphalt pavers

PubMed Central

Burstyn, Igor; Kromhout, Hans; Johansen, Christoffer; Langard, Sverre; Kauppinen, Timo; Shaham, Judith; Ferro, Gilles; Boffetta, Paolo

2007-01-01

Objectives To investigate the association between exposures to polycyclic aromatic hydrocarbons (PAH) that arises during asphalt paving, and risk of bladder cancer. Methods 7298 men included in the historical cohort were first employed between 1913 and 1999 in companies applying asphalt in Denmark, Norway, Finland and Israel. The minimal duration of employment for inclusion in the cohort was two seasons of work. Occupational histories were extracted from personnel files. A follow‐up for cancer incidence was conducted through national cancer registries. The authors estimated exposures to benzo(a)pyrene as a marker for 4–6 ring PAH. Exposures were reconstructed by using information about changes in asphalt paving technology in each company over time, the modelled relation between production characteristics and exposure levels, and job histories. Relative risks and associated 95% confidence intervals were estimated using Poisson regression. Results 48 bladder cancers among asphalt paving workers were detected; of these, 39 cases were exposed at least 15 years before the diagnosis. Cumulative exposure to PAH was not associated with the incidence of bladder cancer. The association with average exposure became stronger when 15‐year lag was considered, revealing a twofold increase in relative bladder cancer risk in the two higher exposure categories. There was an indication of exposure‐response association with lagged averaged exposure. Risk estimates were adjusted for age, country, duration of employment and calendar period, did not show heterogeneity among countries and did not materially change when re‐estimated after excluding non‐primary cancers from follow‐up. Previously conducted sensitivity analysis indicates that confounding by cigarette smoking is an unlikely explanation for the observed exposure‐response trends. Conclusions The authors were unable to control for all possible sources of confounding and bias. The results do not allow conclusion on the presence or absence of a causal link between exposures to PAH and risk of bladder cancer among asphalt workers. PMID:17332134

Lived Lives: A Pavee Perspective. An arts-science community intervention around suicide in an indigenous ethnic minority

PubMed Central

Malone, Kevin M.; McGuinness, Seamus G.; Cleary, Eimear; Jefferies, Janis; Owens, Christabel; Kelleher, Cecily C.

2017-01-01

Background: Suicide is a significant public health concern, which impacts on health outcomes. Few suicide research studies have been interdisciplinary. We combined a psychobiographical autopsy with a visual arts autopsy, in which families donated stories, images and objects associated with the lived life of a loved one lost to suicide. From this interdisciplinary research platform, a mediated exhibition was created ( Lived Lives) with artist, scientist and families, co-curated by communities, facilitating dialogue, response and public action around suicide prevention. Indigenous ethnic minorities (IEMs) bear a significant increased risk for suicide. Irish Travellers are an IEM with social and cultural parallels with IEMs internationally, experiencing racism, discrimination, and poor health outcomes including elevated suicide rates (SMR 6.6). Methods: An adjusted Lived Lives exhibition, Lived Lives: A Pavee Perspective manifested in Pavee Point, the national Traveller and Roma Centre. The project was evaluated by the Travelling Community as to how it related to suicide in their community, how it has shaped their understanding of suicide and its impacts, and its relevance to other socio-cultural contexts, nationally and internationally. The project also obtained feedback from all relevant stakeholders. Evaluation was carried out by an international visual arts research advisor and an independent observer from the field of suicide research. Results: Outputs included an arts-science mediated exhibition with reference to elevated Irish Traveller suicide rates. Digital online learning materials about suicide and its aftermath among Irish Travellers were also produced. The project reached its target audience, with a high level of engagement from members of the Travelling Community. Discussion: The Lived Lives methodology navigated the societal barriers of stigma and silence to foster communication and engagement, working with cultural values, consistent with an adapted intervention. Feedback from this project can inform awareness, health promotion, education and interventions around suicide and its aftermath in IEMs. PMID:28540367

Lived Lives: A Pavee Perspective. An arts-science community intervention around suicide in an indigenous ethnic minority.

PubMed

Malone, Kevin M; McGuinness, Seamus G; Cleary, Eimear; Jefferies, Janis; Owens, Christabel; Kelleher, Cecily C

2017-04-13

Background: Suicide is a significant public health concern, which impacts on health outcomes. Few suicide research studies have been interdisciplinary. We combined a psychobiographical autopsy with a visual arts autopsy, in which families donated stories, images and objects associated with the lived life of a loved one lost to suicide. From this interdisciplinary research platform, a mediated exhibition was created ( Lived Lives ) with artist, scientist and families, co-curated by communities, facilitating dialogue, response and public action around suicide prevention. Indigenous ethnic minorities (IEMs) bear a significant increased risk for suicide. Irish Travellers are an IEM with social and cultural parallels with IEMs internationally, experiencing racism, discrimination, and poor health outcomes including elevated suicide rates (SMR 6.6). Methods: An adjusted Lived Lives exhibition, Lived Lives: A Pavee Perspective manifested in Pavee Point, the national Traveller and Roma Centre. The project was evaluated by the Travelling Community as to how it related to suicide in their community, how it has shaped their understanding of suicide and its impacts, and its relevance to other socio-cultural contexts, nationally and internationally. The project also obtained feedback from all relevant stakeholders. Evaluation was carried out by an international visual arts research advisor and an independent observer from the field of suicide research. Results: Outputs included an arts-science mediated exhibition with reference to elevated Irish Traveller suicide rates. Digital online learning materials about suicide and its aftermath among Irish Travellers were also produced. The project reached its target audience, with a high level of engagement from members of the Travelling Community. Discussion: The Lived Lives methodology navigated the societal barriers of stigma and silence to foster communication and engagement, working with cultural values, consistent with an adapted intervention. Feedback from this project can inform awareness, health promotion, education and interventions around suicide and its aftermath in IEMs.

PAVES: A Presentation Strategy for Beginning Presenters in Inclusive Environments

ERIC Educational Resources Information Center

Combes, Bertina H.; Walker, Michelle; Harrell, Pamela Esprivalo; Tyler-Wood, Tandra

2008-01-01

Public speaking will continue to be an unsettling experience for some students, including those with disabilities. Experts have suggested several reasons for fearing public speaking; adequate preparation and practice can alleviate most of them. Using the PAVES (Posture, Attitude, Voice, Eye Contact, Smile) strategy described in this article can…

17. CAPE COD AIR STATION PAVE PAWS FACILITY AERIAL VIEW ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

17. CAPE COD AIR STATION PAVE PAWS FACILITY AERIAL VIEW WITH PROJECT NEARING COMPLETION. VIEW SHOWS "A" FACE (LEFT) AND "B" FACE OF RADAR ARRAY SYSTEM. NOTE THAT NORTH IS GENERALLY TO RIGHT OF VIEW. - Cape Cod Air Station, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

47. CAPE COD AIR STATION PAVE PAWS FACILITY AERIAL VIEW ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

47. CAPE COD AIR STATION PAVE PAWS FACILITY AERIAL VIEW OF "A" FACE (LEFT) WITH CLEANING SYSTEM INSTALLED (NOW REMOVED) AND "B" FACE (RIGHT) WITH CONSTRUCTION CRANE IN USE. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

Mechanistic interpretation of nondestructive pavement testing deflections

NASA Astrophysics Data System (ADS)

Hoffman, M. S.; Thompson, M. R.

1981-06-01

A method for the back calculation of material properties in flexible pavements based on the interpretation of surface deflection measurements is proposed. The ILLI-PAVE, a stress-dependent finite element pavement model, was used to generate data for developing algorithms and nomographs for deflection basin interpretation. Twenty four different flexible pavement sections throughout the State of Illinois were studied. Deflections were measured and loading mode effects on pavement response were investigated. The factors controlling the pavement response to different loading modes are identified and explained. Correlations between different devices are developed. The back calculated parameters derived from the proposed evaluation procedure can be used as inputs for asphalt concrete overlay design.

Stable black phosphorus quantum dots for alkali PH sensor

NASA Astrophysics Data System (ADS)

Guo, Weilan; Song, Haizeng; Yan, Shancheng

2018-01-01

Black phosphorus, as a new two-dimensional material has been widely used in sensors, photovoltaic devices, etc. However, thin layered black phosphorus chemically degrades rapidly under ambient and aqueous conditions, which hinders the application of it in the chemical sensors. In this work, stable black phosphorus quantum dots (BPQDs) in solution are successfully synthesized by functionalization with 4-nitrobenzene-diazonium (4-NBD). The stable BPQDs are investigated by TEM, AFM, Raman, and UV-absorption. As a potential application, the stable BPQDs are used as sensors in alkali solution, which exhibit outstanding performance. Our work paves the way towards a new application with BPQDs in solution.

Spiral-like multi-beam emission via transformation electromagnetics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tichit, Paul-Henri, E-mail: paul-henri.tichit@u-psud.fr; Burokur, Shah Nawaz, E-mail: shah-nawaz.burokur@u-psud.fr; Lustrac, André de, E-mail: andre.de-lustrac@u-psud.fr

Transformation electromagnetics offers an unconventional approach for the design of novel radiating devices. Here, we propose an electromagnetic metamaterial able to split an isotropic radiation into multiple directive beams. By applying transformations that modify distance and angles, we show how the multiple directive beams can be steered at will. We describe transformation of the metric space and the calculation of the material parameters. Different transformations are proposed for a possible physical realization through the use of engineered artificial metamaterials. Full wave simulations are performed to validate the proposed approach. The idea paves the way to interesting applications in various domainsmore » in microwave and optical regimes.« less

Nitrogen and Fluorine-Codoped Carbon Nanowire Aerogels as Metal-Free Electrocatalysts for Oxygen Reduction Reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Shaofang; Zhu, Chengzhou; Song, Junhua

2017-07-11

The development of active, durable, and low-cost catalysts to replace noble metal-based materials is highly desirable to promote the sluggish oxygen reduction reaction in fuel cells. Herein, nitrogen and fluorine-codoped three-dimensional carbon nanowire aerogels, composed of interconnected carbon nanowires, were synthesized for the first time by a hydrothermal carbonization process. Owing to their porous nanostructures and heteroatom-doping, the as-prepared carbon nanowire aerogels, with optimized composition, present excellent electrocatalytic activity that is comparable to commercial Pt/C. Remarkably, the aerogels also exhibit superior stability and methanol tolerance. This synthesis procedure paves a new way to design novel heteroatomdoped catalysts.

Direct synthesis of multilayer graphene on an insulator by Ni-induced layer exchange growth of amorphous carbon

NASA Astrophysics Data System (ADS)

Murata, H.; Toko, K.; Saitoh, N.; Yoshizawa, N.; Suemasu, T.

2017-01-01

Multilayer graphene (MLG) growth on arbitrary substrates is desired for incorporating carbon wiring and heat spreaders into electronic devices. We investigated the metal-induced layer exchange growth of a sputtered amorphous C layer using Ni as a catalyst. A MLG layer uniformly formed on a SiO2 substrate at 600 °C by layer exchange between the C and Ni layers. Raman spectroscopy and electron microscopy showed that the resulting MLG layer was highly oriented and contained relatively few defects. The present investigation will pave the way for advanced electronic devices integrated with carbon materials.

Direct patterning of organic conductors on knitted textiles for long-term electrocardiography

NASA Astrophysics Data System (ADS)

Takamatsu, Seiichi; Lonjaret, Thomas; Crisp, Dakota; Badier, Jean-Michel; Malliaras, George G.; Ismailova, Esma

2015-10-01

Wearable sensors are receiving a great deal of attention as they offer the potential to become a key technological tool for healthcare. In order for this potential to come to fruition, new electroactive materials endowing high performance need to be integrated with textiles. Here we present a simple and reliable technique that allows the patterning of conducting polymers on textiles. Electrodes fabricated using this technique showed a low impedance contact with human skin, were able to record high quality electrocardiograms at rest, and determine heart rate even when the wearer was in motion. This work paves the way towards imperceptible electrophysiology sensors for human health monitoring.

Multilevel radiative thermal memory realized by the hysteretic metal-insulator transition of vanadium dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ito, Kota, E-mail: kotaito@mosk.tytlabs.co.jp; Nishikawa, Kazutaka; Iizuka, Hideo

Thermal information processing is attracting much interest as an analog of electronic computing. We experimentally demonstrated a radiative thermal memory utilizing a phase change material. The hysteretic metal-insulator transition of vanadium dioxide (VO{sub 2}) allows us to obtain a multilevel memory. We developed a Preisach model to explain the hysteretic radiative heat transfer between a VO{sub 2} film and a fused quartz substrate. The transient response of our memory predicted by the Preisach model agrees well with the measured response. Our multilevel thermal memory paves the way for thermal information processing as well as contactless thermal management.

Single-shot time stretch stimulated Raman spectroscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Saltarelli, Francesco; Kumar, Vikas; Viola, Daniele; Crisafi, Francesco; Preda, Fabrizio; Cerullo, Giulio; Polli, Dario

2017-02-01

Stimulated Raman scattering spectroscopy is a powerful technique for label-free molecular identification, but its broadband implementation is technically challenging. We introduce and experimentally demonstrate a novel approach based on photonic time stretch. The broadband femtosecond Stokes pulse, after interacting with the sample, is stretched by a telecom fiber to 15ns, mapping its spectrum in time. The signal is sampled through a fast analog-to-digital converter, providing single-shot spectra at 80-kHz rate. We demonstrate 10^-5 sensitivity over 500 cm-1 in the C-H region. Our results pave the way to high-speed broadband vibrational imaging for materials science and biophotonics.

Fermi Surface of Metallic V_{2}O_{3} from Angle-Resolved Photoemission: Mid-level Filling of e_{g}^{π} Bands.

PubMed

Lo Vecchio, I; Denlinger, J D; Krupin, O; Kim, B J; Metcalf, P A; Lupi, S; Allen, J W; Lanzara, A

2016-10-14

Using angle resolved photoemission spectroscopy, we report the first band dispersions and distinct features of the bulk Fermi surface (FS) in the paramagnetic metallic phase of the prototypical metal-insulator transition material V_{2}O_{3}. Along the c axis we observe both an electron pocket and a triangular holelike FS topology, showing that both V 3d a_{1g} and e_{g}^{π} states contribute to the FS. These results challenge the existing correlation-enhanced crystal field splitting theoretical explanation for the transition mechanism and pave the way for the solution of this mystery.

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Xiao; Wu, Linzhi, E-mail: wlz@hit.edu.cn

The previously reported magical thermal devices, such as the thermal invisible cloak and the thermal concentrator, are generalized into one general case named here thermal illusion device. The thermal illusion device is displayed by the design of a thermal reshaper which can reshape an arbitrary thermal object into another one with arbitrary cross section. General expressions of the material parameters for the thermal reshaper are derived unambiguously to greatly facilitate the design of general thermal illusion device. We believe that this work will broaden the current research and pave a path to the thermal invisibility. Numerical simulations show good agreementmore » with the analytical results of the thermal illusion device.« less

Solar energy collection system

NASA Technical Reports Server (NTRS)

Miller, C. G.; Stephens, J. B. (Inventor)

1979-01-01

A fixed, linear, ground-based primary reflector having an extended curved sawtooth-contoured surface covered with a metalized polymeric reflecting material, reflects solar energy to a movably supported collector that is kept at the concentrated line focus reflector primary. The primary reflector may be constructed by a process utilizing well known freeway paving machinery. The solar energy absorber is preferably a fluid transporting pipe. Efficient utilization leading to high temperatures from the reflected solar energy is obtained by cylindrical shaped secondary reflectors that direct off-angle energy to the absorber pipe. A seriatim arrangement of cylindrical secondary reflector stages and spot-forming reflector stages produces a high temperature solar energy collection system of greater efficiency.

The Candida albicans Biofilm Matrix: Composition, Structure and Function.

PubMed

Pierce, Christopher G; Vila, Taissa; Romo, Jesus A; Montelongo-Jauregui, Daniel; Wall, Gina; Ramasubramanian, Anand; Lopez-Ribot, Jose L

2017-03-01

A majority of infections caused by Candida albicans -the most frequent fungal pathogen-are associated with biofilm formation. A salient feature of C. albicans biofilms is the presence of the biofilm matrix. This matrix is composed of exopolymeric materials secreted by sessile cells within the biofilm, in which all classes of macromolecules are represented, and provides protection against environmental challenges. In this review, we summarize the knowledge accumulated during the last two decades on the composition, structure, and function of the C. albicans biofilm matrix. Knowledge of the matrix components, its structure, and function will help pave the way to novel strategies to combat C. albicans biofilm infections.

The Candida albicans Biofilm Matrix: Composition, Structure and Function

PubMed Central

Pierce, Christopher G.; Vila, Taissa; Romo, Jesus A.; Montelongo-Jauregui, Daniel; Wall, Gina; Ramasubramanian, Anand; Lopez-Ribot, Jose L.

2017-01-01

A majority of infections caused by Candida albicans—the most frequent fungal pathogen—are associated with biofilm formation. A salient feature of C. albicans biofilms is the presence of the biofilm matrix. This matrix is composed of exopolymeric materials secreted by sessile cells within the biofilm, in which all classes of macromolecules are represented, and provides protection against environmental challenges. In this review, we summarize the knowledge accumulated during the last two decades on the composition, structure, and function of the C. albicans biofilm matrix. Knowledge of the matrix components, its structure, and function will help pave the way to novel strategies to combat C. albicans biofilm infections. PMID:28516088

36 CFR 7.15 - Shenandoah National Park.

Code of Federal Regulations, 2010 CFR

2010-07-01

... those areas of the park which are more than 250 yards from a paved road, and more than one-half mile from any park facilities other than trails, unpaved roads and trail shelters. The Superintendent may...; (3) No person or group may backcountry camp: (i) Within 250 yards or in view from any paved park road...

Evaluation of fly ash in water reduced paving mixtures.

DOT National Transportation Integrated Search

1985-06-01

Fly ash was used to replace 15% of the cement in C3WR and C6WR concrete : paving mixes containing ASTM C494 Type A water reducin9 admixtures. Two Class : C ashes and one Class F ash from Iowa approved sources were examined in each : mix. When Class C...

45. CAPE COD AIR STATION PAVE PAWS FACILITY BUILDING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

45. CAPE COD AIR STATION PAVE PAWS FACILITY - BUILDING ELEVATION VIEW WITH BUILDING METAL SIDING BEING APPLIED ON "A" FACE (LEFT) AND "B" FACE (RIGHT). NOTE THAT NORTH IS GENERALLY TO RIGHT OF VIEW. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

Recent developments in turning hardened steels - A review

NASA Astrophysics Data System (ADS)

Sivaraman, V.; Prakash, S.

2017-05-01

Hard materials ranging from HRC 45 - 68 such as hardened AISI H13, AISI 4340, AISI 52100, D2 STL, D3 STEEL Steel etc., need super hard tool materials to machine. Turning of these hard materials is termed as hard turning. Hard turning makes possible direct machining of the hard materials and also eliminates the lubricant requirement and thus favoring dry machining. Hard turning is a finish turning process and hence conventional grinding is not required. Development of the new advanced super hard tool materials such as ceramic inserts, Cubic Boron Nitride, Polycrystalline Cubic Boron Nitride etc. enabled the turning of these materials. PVD and CVD methods of coating have made easier the production of single and multi layered coated tool inserts. Coatings of TiN, TiAlN, TiC, Al2O3, AlCrN over cemented carbide inserts has lead to the machining of difficult to machine materials. Advancement in the process of hard machining paved way for better surface finish, long tool life, reduced tool wear, cutting force and cutting temperatures. Micro and Nano coated carbide inserts, nanocomposite coated PCBN inserts, micro and nano CBN coated carbide inserts and similar developments have made machining of hardened steels much easier and economical. In this paper, broad literature review on turning of hardened steels including optimizing process parameters, cooling requirements, different tool materials etc., are done.

Trapping charges at grain boundaries and degradation of CH3NH3Pb(I1-x Br x )3 perovskite solar cells.

PubMed

Nguyen, Bich Phuong; Kim, Gee Yeong; Jo, William; Kim, Byeong Jo; Jung, Hyun Suk

2017-08-04

The electrical properties of CH 3 NH 3 Pb(I 1-x Br x ) 3 (x = 0.13) perovskite materials were investigated under ambient conditions. The local work function and the local current were measured using Kelvin probe force microscopy and conductive atomic force microscopy, respectively. The degradation of the perovskite layers depends on their grain size. As the material degrades, an additional peak in the surface potential appears simultaneously with a sudden increase and subsequent relaxation of the local current. The potential bending at the grain boundaries and the intragrains is the most likely reason for the change of the local current surface of the perovskite layers. The improved understanding of the degradation mechanism garnered from this study helps pave the way toward an improved photo-conversion efficiency in perovskite solar cells.

Trapping charges at grain boundaries and degradation of CH3NH3Pb(I1-x Br x )3 perovskite solar cells

NASA Astrophysics Data System (ADS)

Phuong Nguyen, Bich; Kim, Gee Yeong; Jo, William; Kim, Byeong Jo; Jung, Hyun Suk

2017-08-01

The electrical properties of CH3NH3Pb(I1-x Br x )3 (x = 0.13) perovskite materials were investigated under ambient conditions. The local work function and the local current were measured using Kelvin probe force microscopy and conductive atomic force microscopy, respectively. The degradation of the perovskite layers depends on their grain size. As the material degrades, an additional peak in the surface potential appears simultaneously with a sudden increase and subsequent relaxation of the local current. The potential bending at the grain boundaries and the intragrains is the most likely reason for the change of the local current surface of the perovskite layers. The improved understanding of the degradation mechanism garnered from this study helps pave the way toward an improved photo-conversion efficiency in perovskite solar cells.

Atoms and molecules in cavities, from weak to strong coupling in quantum-electrodynamics (QED) chemistry

PubMed Central

Flick, Johannes; Ruggenthaler, Michael; Appel, Heiko

2017-01-01

In this work, we provide an overview of how well-established concepts in the fields of quantum chemistry and material sciences have to be adapted when the quantum nature of light becomes important in correlated matter–photon problems. We analyze model systems in optical cavities, where the matter–photon interaction is considered from the weak- to the strong-coupling limit and for individual photon modes as well as for the multimode case. We identify fundamental changes in Born–Oppenheimer surfaces, spectroscopic quantities, conical intersections, and efficiency for quantum control. We conclude by applying our recently developed quantum-electrodynamical density-functional theory to spontaneous emission and show how a straightforward approximation accurately describes the correlated electron–photon dynamics. This work paves the way to describe matter–photon interactions from first principles and addresses the emergence of new states of matter in chemistry and material science. PMID:28275094

Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

PubMed Central

Zhang, Yanwen; Stocks, G. Malcolm; Jin, Ke; Lu, Chenyang; Bei, Hongbin; Sales, Brian C.; Wang, Lumin; Béland, Laurent K.; Stoller, Roger E.; Samolyuk, German D.; Caro, Magdalena; Caro, Alfredo; Weber, William J.

2015-01-01

A grand challenge in materials research is to understand complex electronic correlation and non-equilibrium atomic interactions, and how such intrinsic properties and dynamic processes affect energy transfer and defect evolution in irradiated materials. Here we report that chemical disorder, with an increasing number of principal elements and/or altered concentrations of specific elements, in single-phase concentrated solid solution alloys can lead to substantial reduction in electron mean free path and orders of magnitude decrease in electrical and thermal conductivity. The subsequently slow energy dissipation affects defect dynamics at the early stages, and consequentially may result in less deleterious defects. Suppressed damage accumulation with increasing chemical disorder from pure nickel to binary and to more complex quaternary solid solutions is observed. Understanding and controlling energy dissipation and defect dynamics by altering alloy complexity may pave the way for new design principles of radiation-tolerant structural alloys for energy applications. PMID:26507943

General solution for quantitative dark-field contrast imaging with grating interferometers

NASA Astrophysics Data System (ADS)

Strobl, M.

2014-11-01

Grating interferometer based imaging with X-rays and neutrons has proven to hold huge potential for applications in key research fields conveying biology and medicine as well as engineering and magnetism, respectively. The thereby amenable dark-field imaging modality implied the promise to access structural information beyond reach of direct spatial resolution. However, only here a yet missing approach is reported that finally allows exploiting this outstanding potential for non-destructive materials characterizations. It enables to obtain quantitative structural small angle scattering information combined with up to 3-dimensional spatial image resolution even at lab based x-ray or at neutron sources. The implied two orders of magnitude efficiency gain as compared to currently available techniques in this regime paves the way for unprecedented structural investigations of complex sample systems of interest for material science in a vast range of fields.

Self-shaping of bioinspired chiral composites

NASA Astrophysics Data System (ADS)

Rong, Qing-Qing; Cui, Yu-Hong; Shimada, Takahiro; Wang, Jian-Shan; Kitamura, Takayuki

2014-08-01

Self-shaping materials such as shape memory polymers have recently drawn considerable attention owing to their high shape-changing ability in response to changes in ambient conditions, and thereby have promising applications in the biomedical, biosensing, soft robotics and aerospace fields. Their design is a crucial issue of both theoretical and technological interest. Motivated by the shape-changing ability of Towel Gourd tendril helices during swelling/deswelling, we present a strategy for realizing self-shaping function through the deformation of micro/nanohelices. To guide the design and fabrication of self-shaping materials, the shape equations of bent configurations, twisted belts, and helices of slender chiral composite are developed using the variation method. Furthermore, it is numerically shown that the shape changes of a chiral composite can be tuned by the deformation of micro/nanohelices and the fabricated fiber directions. This work paves a new way to create self-shaping composites.

Translational mini-screw implant research.

PubMed

Rossouw, Emile

2014-09-01

It is important to thoroughly test new materials as well as techniques when these innovations are to be utilized in the human clinical situation. Translational research fills this important niche. The purpose of translational research is to establish the continuity of evidence from the laboratory to the clinic and in so-doing, provide evidence that the material is functioning appropriately and that the process in the human will be successful. This concept applies to the mini-screw implant; which, has been very successfully introduced into the orthodontic armamentarium over the last decade for application as a temporary anchorage device. The examples of translational research that will be illustrated in this paper have paved the way to ensure that clinicians have evidence to confidently utilize mini-screw implants in orthodontic practice. Needless to say, more studies are needed to ensure a safe, effective and efficient manner to practice orthodontics. © 2014 British Orthodontic Society.

Subatomic deformation driven by vertical piezoelectricity from CdS ultrathin films

PubMed Central

Wang, Xuewen; He, Xuexia; Zhu, Hongfei; Sun, Linfeng; Fu, Wei; Wang, Xingli; Hoong, Lai Chee; Wang, Hong; Zeng, Qingsheng; Zhao, Wu; Wei, Jun; Jin, Zhong; Shen, Zexiang; Liu, Jie; Zhang, Ting; Liu, Zheng

2016-01-01

Driven by the development of high-performance piezoelectric materials, actuators become an important tool for positioning objects with high accuracy down to nanometer scale, and have been used for a wide variety of equipment, such as atomic force microscopy and scanning tunneling microscopy. However, positioning at the subatomic scale is still a great challenge. Ultrathin piezoelectric materials may pave the way to positioning an object with extreme precision. Using ultrathin CdS thin films, we demonstrate vertical piezoelectricity in atomic scale (three to five space lattices). With an in situ scanning Kelvin force microscopy and single and dual ac resonance tracking piezoelectric force microscopy, the vertical piezoelectric coefficient (d33) up to 33 pm·V−1 was determined for the CdS ultrathin films. These findings shed light on the design of next-generation sensors and microelectromechanical devices. PMID:27419234

Spin Hall Effects in Metallic Antiferromagnets

DOE PAGES

Zhang, Wei; Jungfleisch, Matthias B.; Jiang, Wanjun; ...

2014-11-04

In this paper, we investigate four CuAu-I-type metallic antiferromagnets for their potential as spin current detectors using spin pumping and inverse spin Hall effect. Nontrivial spin Hall effects were observed for FeMn, PdMn, and IrMn while a much higher effect was obtained for PtMn. Using thickness-dependent measurements, we determined the spin diffusion lengths of these materials to be short, on the order of 1 nm. The estimated spin Hall angles of the four materials follow the relationship PtMn > IrMn > PdMn > FeMn, highlighting the correlation between the spin-orbit coupling of nonmagnetic species and the magnitude of the spinmore » Hall effect in their antiferromagnetic alloys. These experiments are compared with first-principles calculations. Finally, engineering the properties of the antiferromagnets as well as their interfaces can pave the way for manipulation of the spin dependent transport properties in antiferromagnet-based spintronics.« less

Epoxy Chip-in-Carrier Integration and Screen-Printed Metalization for Multichannel Microfluidic Lab-on-CMOS Microsystems.

PubMed

Li, Lin; Yin, Heyu; Mason, Andrew J

2018-04-01

The integration of biosensors, microfluidics, and CMOS instrumentation provides a compact lab-on-CMOS microsystem well suited for high throughput measurement. This paper describes a new epoxy chip-in-carrier integration process and two planar metalization techniques for lab-on-CMOS that enable on-CMOS electrochemical measurement with multichannel microfluidics. Several design approaches with different fabrication steps and materials were experimentally analyzed to identify an ideal process that can achieve desired capability with high yield and low material and tool cost. On-chip electrochemical measurements of the integrated assembly were performed to verify the functionality of the chip-in-carrier packaging and its capability for microfluidic integration. The newly developed CMOS-compatible epoxy chip-in-carrier process paves the way for full implementation of many lab-on-CMOS applications with CMOS ICs as core electronic instruments.

Direct Desktop Printed-Circuits-on-Paper Flexible Electronics

PubMed Central

Zheng, Yi; He, Zhizhu; Gao, Yunxia; Liu, Jing

2013-01-01

There currently lacks of a way to directly write out electronics, just like printing pictures on paper by an office printer. Here we show a desktop printing of flexible circuits on paper via developing liquid metal ink and related working mechanisms. Through modifying adhesion of the ink, overcoming its high surface tension by dispensing machine and designing a brush like porous pinhead for printing alloy and identifying matched substrate materials among different papers, the slightly oxidized alloy ink was demonstrated to be flexibly printed on coated paper, which could compose various functional electronics and the concept of Printed-Circuits-on-Paper was thus presented. Further, RTV silicone rubber was adopted as isolating inks and packaging material to guarantee the functional stability of the circuit, which suggests an approach for printing 3D hybrid electro-mechanical device. The present work paved the way for a low cost and easygoing method in directly printing paper electronics.

Ultrasound-Induced Organogel Formation Followed by Thin Film Fabrication via Simple Doctor Blading Technique for Field-Effect Transistor Applications.

PubMed

Xu, Jiaju; Wang, Yulong; Shan, Haiquan; Lin, Yiwei; Chen, Qian; Roy, V A L; Xu, Zongxiang

2016-07-27

We demonstrate doctor blading technique to fabricate high performance transistors made up of printed small molecular materials. In this regard, we synthesize a new soluble phthalocyanine, tetra-n-butyl peripheral substituted copper(II) phthalocaynine (CuBuPc), that can easily undergo gel formation upon ultrasonic irradiation, leading to the formation of three-dimensional (3D) network composed of one-dimensional (1D) nanofibers structure. Finally, taking the advantage of thixotropic nature of the CuBuPc organogel, we use the doctor blade processing technique that limits the material wastage for the fabrication of transistor devices. Due to the ultrasound induced stronger π-π interaction, the transistor fabricated by doctor blading based on CuBuPc organogel exhibits significant increase in charge carrier mobility in comparison with other solution process techniques, thus paving a way for a simple and economically viable preparation of electronic circuits.

Optics Communications: Special issue on Polymer Photonics and Its Applications

NASA Astrophysics Data System (ADS)

Zhang, Ziyang; Pitwon, Richard C. A.; Feng, Jing

2016-03-01

In the last decade polymer photonics has witnessed a tremendous boost in research efforts and practical applications. Polymer materials can be engineered to exhibit unique optical and electrical properties. Extremely transparent and reliable passive optical polymers have been made commercially available and paved the ground for the development of various waveguide components. Advancement in the research activities regarding the synthesis of active polymers has enabled devices such as ultra-fast electro-optic modulators, efficient white light emitting diodes, broadband solar cells, flexible displays, and so on. The fabrication technology is not only fast and cost-effective, but also provides flexibility and broad compatibility with other semiconductor processing technologies. Reports show that polymers have been integrated in photonic platforms such as silicon-on-insulator (SOI), III-V semiconductors, and silica PLCs, and vice versa, photonic components made from a multitude of materials have been integrated, in a heterogeneous/hybrid manner, in polymer photonic platforms.

Ice Nucleation Properties of Oxidized Carbon Nanomaterials

PubMed Central

2015-01-01

Heterogeneous ice nucleation is an important process in many fields, particularly atmospheric science, but is still poorly understood. All known inorganic ice nucleating particles are relatively large in size and tend to be hydrophilic. Hence it is not obvious that carbon nanomaterials should nucleate ice. However, in this paper we show that four different readily water-dispersible carbon nanomaterials are capable of nucleating ice. The tested materials were carboxylated graphene nanoflakes, graphene oxide, oxidized single walled carbon nanotubes and oxidized multiwalled carbon nanotubes. The carboxylated graphene nanoflakes have a diameter of ∼30 nm and are among the smallest entities observed so far to nucleate ice. Overall, carbon nanotubes were found to nucleate ice more efficiently than flat graphene species, and less oxidized materials nucleated ice more efficiently than more oxidized species. These well-defined carbon nanomaterials may pave the way to bridging the gap between experimental and computational studies of ice nucleation. PMID:26267196

Pattern-free thermal modulator via thermal radiation between Van der Waals materials

NASA Astrophysics Data System (ADS)

Liu, Xianglei; Shen, Jiadong; Xuan, Yimin

2017-10-01

Modulating heat flux provides a platform for a plethora of emerging devices such as thermal diodes, thermal transistors, and thermal memories. Here, a pattern-free noncontact thermal modulator is proposed based on the mechanical rotation between two Van der Waals films with optical axes parallel to the surfaces. A modulation contrast can reach a value higher than 5 for hexagonal Boron Nitride (hBN) films separated by a nanoscale gap distance. The dominant radiative heat exchange comes from the excitation of both Type I and Type II hyperbolic surface phonon polaritons (HSPhPs) at the vacuum-hBN interface for different orientations, while the large modulation contrast is mainly attributed to the mismatching Type I HSPhPs induced by rotation. This work opens the possibility to design cheap thermal modulators without relying on nanofabrication techniques, and paves the way to apply natural Van der Waals materials in manipulating heat currents in an active way.

Nanometric holograms based on a topological insulator material

PubMed Central

Yue, Zengji; Xue, Gaolei; Liu, Juan; Wang, Yongtian; Gu, Min

2017-01-01

Holography has extremely extensive applications in conventional optical instruments spanning optical microscopy and imaging, three-dimensional displays and metrology. To integrate holography with modern low-dimensional electronic devices, holograms need to be thinned to a nanometric scale. However, to keep a pronounced phase shift modulation, the thickness of holograms has been generally limited to the optical wavelength scale, which hinders their integration with ultrathin electronic devices. Here, we break this limit and achieve 60 nm holograms using a topological insulator material. We discover that nanometric topological insulator thin films act as an intrinsic optical resonant cavity due to the unequal refractive indices in their metallic surfaces and bulk. The resonant cavity leads to enhancement of phase shifts and thus the holographic imaging. Our work paves a way towards integrating holography with flat electronic devices for optical imaging, data storage and information security. PMID:28516906

Radiation hardness of Ce-doped sol-gel silica fibers for high energy physics applications.

PubMed

Cova, Francesca; Moretti, Federico; Fasoli, Mauro; Chiodini, Norberto; Pauwels, Kristof; Auffray, Etiennette; Lucchini, Marco Toliman; Baccaro, Stefania; Cemmi, Alessia; Bártová, Hana; Vedda, Anna

2018-02-15

The results of irradiation tests on Ce-doped sol-gel silica using x- and γ-rays up to 10 kGy are reported in order to investigate the radiation hardness of this material for high-energy physics applications. Sol-gel silica fibers with Ce concentrations of 0.0125 and 0.05 mol. % are characterized by means of optical absorption and attenuation length measurements before and after irradiation. The two different techniques give comparable results, evidencing the formation of a main broad radiation-induced absorption band, peaking at about 2.2 eV, related to radiation-induced color centers. The results are compared with those obtained on bulk silica. This study reveals that an improvement of the radiation hardness of Ce-doped silica fibers can be achieved by reducing Ce content inside the fiber core, paving the way for further material development.

Infrared fingerprints of few-layer black phosphorus.

PubMed

Zhang, Guowei; Huang, Shenyang; Chaves, Andrey; Song, Chaoyu; Özçelik, V Ongun; Low, Tony; Yan, Hugen

2017-01-06

Black phosphorus is an infrared layered material. Its bandgap complements other widely studied two-dimensional materials: zero-gap graphene and visible/near-infrared gap transition metal dichalcogenides. Although highly desirable, a comprehensive infrared characterization is still lacking. Here we report a systematic infrared study of mechanically exfoliated few-layer black phosphorus, with thickness ranging from 2 to 15 layers and photon energy spanning from 0.25 to 1.36 eV. Each few-layer black phosphorus exhibits a thickness-dependent unique infrared spectrum with a series of absorption resonances, which reveals the underlying electronic structure evolution and serves as its infrared fingerprints. Surprisingly, unexpected absorption features, which are associated with the forbidden optical transitions, have been observed. Furthermore, we unambiguously demonstrate that controllable uniaxial strain can be used as a convenient and effective approach to tune the electronic structure of few-layer black phosphorus. Our study paves the way for black phosphorus applications in infrared photonics and optoelectronics.

Large Magnetoelectric Coupling Near Room Temperature in Synthetic Melanostibite Mn2 FeSbO6.

PubMed

Dos Santos-García, Antonio J; Solana-Madruga, Elena; Ritter, Clemens; Andrada-Chacón, Adrián; Sánchez-Benítez, Javier; Mompean, Federico J; Garcia-Hernandez, Mar; Sáez-Puche, Regino; Schmidt, Rainer

2017-04-10

Multiferroic materials exhibit two or more ferroic orders and have potential applications as multifunctional materials in the electronics industry. A coupling of ferroelectricity and ferromagnetism is hereby particularly promising. We show that the synthetic melanostibite mineral Mn 2 FeSbO 6 (R3‾ space group) with ilmenite-type structure exhibits cation off-centering that results in alternating modulated displacements, thus allowing antiferroelectricity to occur. Massive magnetoelectric coupling (MEC) and magnetocapacitance effect of up to 4000 % was detected at a record high temperature of 260 K. The multiferroic behavior is based on the imbalance of cationic displacements caused by a magnetostrictive mechanism, which sets up an unprecedented example to pave the way for the development of highly effective MEC devices operational at or near room temperature. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantum Hall effect in a bulk antiferromagnet EuMnBi2 with magnetically confined two-dimensional Dirac fermions.

PubMed

Masuda, Hidetoshi; Sakai, Hideaki; Tokunaga, Masashi; Yamasaki, Yuichi; Miyake, Atsushi; Shiogai, Junichi; Nakamura, Shintaro; Awaji, Satoshi; Tsukazaki, Atsushi; Nakao, Hironori; Murakami, Youichi; Arima, Taka-hisa; Tokura, Yoshinori; Ishiwata, Shintaro

2016-01-01

For the innovation of spintronic technologies, Dirac materials, in which low-energy excitation is described as relativistic Dirac fermions, are one of the most promising systems because of the fascinating magnetotransport associated with extremely high mobility. To incorporate Dirac fermions into spintronic applications, their quantum transport phenomena are desired to be manipulated to a large extent by magnetic order in a solid. We report a bulk half-integer quantum Hall effect in a layered antiferromagnet EuMnBi2, in which field-controllable Eu magnetic order significantly suppresses the interlayer coupling between the Bi layers with Dirac fermions. In addition to the high mobility of more than 10,000 cm(2)/V s, Landau level splittings presumably due to the lifting of spin and valley degeneracy are noticeable even in a bulk magnet. These results will pave a route to the engineering of magnetically functionalized Dirac materials.

Permeability of roads to movement of scrubland lizards and small mammals.

PubMed

Brehme, Cheryl S; Tracey, Jeff A; McClenaghan, Leroy R; Fisher, Robert N

2013-08-01

A primary objective of road ecology is to understand and predict how roads affect connectivity of wildlife populations. Road avoidance behavior can fragment populations, whereas lack of road avoidance can result in high mortality due to wildlife-vehicle collisions. Many small animal species focus their activities to particular microhabitats within their larger habitat. We sought to assess how different types of roads affect the movement of small vertebrates and to explore whether responses to roads may be predictable on the basis of animal life history or microhabitat preferences preferences. We tracked the movements of fluorescently marked animals at 24 sites distributed among 3 road types: low-use dirt, low-use secondary paved, and rural 2-lane highway. Most data we collected were on the San Diego pocket mouse (Chaetodipus fallax), cactus mouse (Peromyscus eremicus), western fence lizard (Sceloporus occidentalis), orange-throated whiptail (Aspidoscelis hyperythra), Dulzura kangaroo rat (Dipodomys simulans) (dirt, secondary paved), and deer mouse (Peromyscus maniculatus) (highway only). San Diego pocket mice and cactus mice moved onto dirt roads but not onto a low-use paved road of similar width or onto the highway, indicating they avoid paved road substrate. Both lizard species moved onto the dirt and secondary paved roads but avoided the rural 2-lane rural highway, indicating they may avoid noise, vibration, or visual disturbance from a steady flow of traffic. Kangaroo rats did not avoid the dirt or secondary paved roads. Overall, dirt and secondary roads were more permeable to species that prefer to forage or bask in open areas of their habitat, rather than under the cover of rocks or shrubs. However, all study species avoided the rural 2-lane highway. Our results suggest that microhabitat use preferences and road substrate help predict species responses to low-use roads, but roads with heavy traffic may deter movement of a much wider range of small animal species. © 2013 Society for Conservation Biology.

Submicron particle monitoring of paving and related road construction operations.

PubMed

Freund, Alice; Zuckerman, Norman; Baum, Lisa; Milek, Debra

2012-01-01

This study identified activities and sources that contribute to ultrafine and other submicron particle exposure that could trigger respiratory symptoms in highway repair workers. Submicron particle monitoring was conducted for paving, milling, and pothole repair operations in a major metropolitan area where several highway repair workers were identified as symptomatic for respiratory illness following exposures at the 2001 World Trade Center disaster site. Exposure assessments were conducted for eight trades involved in road construction using a TSI P-Trak portable condensation particle counter. Direct readings near the workers' breathing zones and observations of activities and potential sources were logged on 7 days on 27 workers using four different models of pavers and two types of millers. Average worker exposure levels ranged from 2 to 3 times background during paving and from 1 to 4 times background during milling. During asphalt paving, average personal exposures to submicron particulates were 25,000-60,000, 28,000-70,000, and 23,000-37,000 particles/ cm(3) for paver operators, screed operators, and rakers, respectively. Average personal exposures during milling were 19,000-111,000, 28,000-81,000, and 19,000 particles/cm(3) for the large miller operators, miller screed operators, and raker, respectively. Personal peak exposures were measured up to 467,000 and 455,000 particles/cm(3) in paving and milling, respectively. Several sources of submicron particles were identified. These included the diesel and electric fired screed heaters; engine exhaust from diesel powered construction vehicles passing by or idling; raking, dumping, and paving of asphalt; exhaust from the hotbox heater; pavement dust or fumes from milling operations, especially when the large miller started and stopped; and secondhand cigarette smoke. To reduce the potential for health effects in workers, over 40 recommendations were made to control exposures, including improved maintenance of paver ventilation systems; diesel fume engineering controls; reduced idling; provision of cabs for the operators; and improved dust suppression systems on the milling machine.

NREL's EVI-Pro Lite Tool Paves the Way for Future Electric Vehicle

Science.gov Websites

Electric Vehicle Infrastructure Planning NREL's EVI-Pro Lite Tool Paves the Way for Future Electric Vehicle electric vehicle charging station To assist state and local governments anticipating this type of growth in simplified version of the Electric Vehicle Infrastructure Projection Tool (EVI-Pro) model. Combining a sleek

46. CAPE COD AIR STATION PAVE PAWS FACILITY BUILDING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

46. CAPE COD AIR STATION PAVE PAWS FACILITY - BUILDING ELEVATION VIEW WITH ALL METAL SIDING INSTALLED AND WITH EMITTER/ANTENNA ARRAY SYSTEM NEARING OCMPLETION ON "B" FACE (RIGHT). VIEW ALSO SHOWS TRAVELING "CLEANING" SYSTEM ON "B" FACE - NOW REMOVED. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

Supramolecular self-assembly of graphene oxide and metal nanoparticles into stacked multilayers by means of a multitasking protein ring

NASA Astrophysics Data System (ADS)

Ardini, Matteo; Golia, Giordana; Passaretti, Paolo; Cimini, Annamaria; Pitari, Giuseppina; Giansanti, Francesco; Leandro, Luana Di; Ottaviano, Luca; Perrozzi, Francesco; Santucci, Sandro; Morandi, Vittorio; Ortolani, Luca; Christian, Meganne; Treossi, Emanuele; Palermo, Vincenzo; Angelucci, Francesco; Ippoliti, Rodolfo

2016-03-01

Graphene oxide (GO) is rapidly emerging worldwide as a breakthrough precursor material for next-generation devices. However, this requires the transition of its two-dimensional layered structure into more accessible three-dimensional (3D) arrays. Peroxiredoxins (Prx) are a family of multitasking redox enzymes, self-assembling into ring-like architectures. Taking advantage of both their symmetric structure and function, 3D reduced GO-based composites are hereby built up. Results reveal that the ``double-faced'' Prx rings can adhere flat on single GO layers and partially reduce them by their sulfur-containing amino acids, driving their stacking into 3D multi-layer reduced GO-Prx composites. This process occurs in aqueous solution at a very low GO concentration, i.e. 0.2 mg ml-1. Further, protein engineering allows the Prx ring to be enriched with metal binding sites inside its lumen. This feature is exploited to both capture presynthesized gold nanoparticles and grow in situ palladium nanoparticles paving the way to straightforward and ``green'' routes to 3D reduced GO-metal composite materials.Graphene oxide (GO) is rapidly emerging worldwide as a breakthrough precursor material for next-generation devices. However, this requires the transition of its two-dimensional layered structure into more accessible three-dimensional (3D) arrays. Peroxiredoxins (Prx) are a family of multitasking redox enzymes, self-assembling into ring-like architectures. Taking advantage of both their symmetric structure and function, 3D reduced GO-based composites are hereby built up. Results reveal that the ``double-faced'' Prx rings can adhere flat on single GO layers and partially reduce them by their sulfur-containing amino acids, driving their stacking into 3D multi-layer reduced GO-Prx composites. This process occurs in aqueous solution at a very low GO concentration, i.e. 0.2 mg ml-1. Further, protein engineering allows the Prx ring to be enriched with metal binding sites inside its lumen. This feature is exploited to both capture presynthesized gold nanoparticles and grow in situ palladium nanoparticles paving the way to straightforward and ``green'' routes to 3D reduced GO-metal composite materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08632a

TRADITIONAL METALLURGY, NANOTECHNOLOGIES AND STRUCTURAL MATERIALS: A SORBY AWARD LECTURE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Louthan, M

2007-07-17

Traditional metallurgical processes are among the many ''old fashion'' practices that use nanoparticles to control the behavior of materials. Many of these practices were developed long before microscopy could resolve nanoscale features, yet the practitioners learned to manipulate and control microstructural elements that they could neither see nor identify. Furthermore, these early practitioners used that control to modify microstructures and develop desired material properties. Centuries old colored glass, ancient high strength steels and medieval organ pipes derived many of their desirable features through control of nanoparticles in their microstructures. Henry Sorby was among the first to recognize that the propertiesmore » of rocks, minerals, metals and organic materials were controlled by microstructure. However, Mr. Sorby was accused of the folly of trying to study mountains with a microscope. Although he could not resolve nanoscale microstructural features, Mr. Sorby's observations revolutionized the study of materials. The importance of nanoscale microstructural elements should be emphasized, however, because the present foundation for structural materials was built by manipulating those features. That foundation currently supports several multibillion dollar industries but is not generally considered when the nanomaterials revolution is discussed. This lecture demonstrates that using nanotechnologies to control the behavior of metallic materials is almost as old as the practice of metallurgy and that many of the emergent nanomaterials technologists are walking along pathways previously paved by traditional metallurgists.« less

Increased costs to US pavement infrastructure from future temperature rise

NASA Astrophysics Data System (ADS)

Underwood, B. Shane; Guido, Zack; Gudipudi, Padmini; Feinberg, Yarden

2017-10-01

Roadway design aims to maximize functionality, safety, and longevity. The materials used for construction, however, are often selected on the assumption of a stationary climate. Anthropogenic climate change may therefore result in rapid infrastructure failure and, consequently, increased maintenance costs, particularly for paved roads where temperature is a key determinant for material selection. Here, we examine the economic costs of projected temperature changes on asphalt roads across the contiguous United States using an ensemble of 19 global climate models forced with RCP 4.5 and 8.5 scenarios. Over the past 20 years, stationary assumptions have resulted in incorrect material selection for 35% of 799 observed locations. With warming temperatures, maintaining the standard practice for material selection is estimated to add approximately US$13.6, US$19.0 and US$21.8 billion to pavement costs by 2010, 2040 and 2070 under RCP4.5, respectively, increasing to US$14.5, US$26.3 and US$35.8 for RCP8.5. These costs will disproportionately affect local municipalities that have fewer resources to mitigate impacts. Failing to update engineering standards of practice in light of climate change therefore significantly threatens pavement infrastructure in the United States.

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacLeod, Bradley A.; Stanton, Noah J.; Gould, Isaac E.

Lightweight, robust, and flexible single-walled carbon nanotube (SWCNT) materials can be processed inexpensively using solution-based techniques, similar to other organic semiconductors. In contrast to many semiconducting polymers, semiconducting SWCNTs (s-SWCNTs) represent unique one-dimensional organic semiconductors with chemical and physical properties that facilitate equivalent transport of electrons and holes. These factors have driven increasing attention to employing s-SWCNTs for electronic and energy harvesting applications, including thermoelectric (TE) generators. Here we demonstrate a combination of ink chemistry, solid-state polymer removal, and charge-transfer doping strategies that enable unprecedented n-type and p-type TE power factors, in the range of 700 μW m –1 Kmore » –2 at 298 K for the same solution-processed highly enriched thin films containing 100% s-SWCNTs. We also demonstrate that the thermal conductivity appears to decrease with decreasing s-SWCNT diameter, leading to a peak material zT ≈ 0.12 for s-SWCNTs with diameters in the range of 1.0 nm. Here, our results indicate that the TE performance of s-SWCNT-only material systems is approaching that of traditional inorganic semiconductors, paving the way for these materials to be used as the primary components for efficient, all-organic TE generators.« less

Experimental investigation of the contact resistance of Graphene/MoS2 interface treated with O2 plasma

NASA Astrophysics Data System (ADS)

Lu, Qin; Liu, Yan; Han, Genquan; Fang, Cizhe; Shao, Yao; Zhang, Jincheng; Hao, Yue

2018-02-01

High contact resistance has been a major bottleneck for MoS2 to achieve high performances among two-dimensional material based optoelectronic and electronic devices. In this study, we investigate the contact resistances of different layered graphene film with MoS2 film with Ti/Au electrodes under different O2 plasma treatment time using the circular transmission line model (CTLM). Annealing process followed O2 plasma process to reduce the oxygen element introduced. Raman and X-ray photoelectric spectroscopy were used to analyze the quality of the materials. Finally, the current and voltage curve indicates good linear characteristics. Under the optimized condition of the O2 plasma treatment, a relatively low contact resistance (∼35.7 Ohm mm) without back gate voltage in single-layer graphene/MoS2 structure at room temperature was achieved compared with the existing reports. This method of introducing graphene as electrodes for MoS2 film demonstrates a remarkable ability to improve the contact resistance, without additional channel doping for two-dimensional materials based devices, which paves the way for MoS2 to be a more promising channel material in optoelectronic and electronic integration.

Strong Intrinsic Spin Hall Effect in the TaAs Family of Weyl Semimetals

NASA Astrophysics Data System (ADS)

Sun, Yan; Zhang, Yang; Felser, Claudia; Yan, Binghai

2016-09-01

Since their discovery, topological insulators are expected to be ideal spintronic materials owing to the spin currents carried by surface states with spin-momentum locking. However, the bulk doping problem remains an obstacle that hinders such an application. In this work, we predict that a newly discovered family of topological materials, the Weyl semimetals, exhibits a large intrinsic spin Hall effect that can be utilized to generate and detect spin currents. Our ab initio calculations reveal a large spin Hall conductivity in the TaAs family of Weyl materials. Considering the low charge conductivity of semimetals, Weyl semimetals are believed to present a larger spin Hall angle (the ratio of the spin Hall conductivity over the charge conductivity) than that of conventional spin Hall systems such as the 4 d and 5 d transition metals. The spin Hall effect originates intrinsically from the bulk band structure of Weyl semimetals, which exhibit a large Berry curvature and spin-orbit coupling, so the bulk carrier problem in the topological insulators is naturally avoided. Our work not only paves the way for employing Weyl semimetals in spintronics, but also proposes a new guideline for searching for the spin Hall effect in various topological materials.

Probing in-plane anisotropy in few-layer ReS2 using low frequency noise measurement.

PubMed

Mitra, Richa; Jariwala, Bhakti; Bhattacharya, Arnab; Das, Anindya

2018-02-19

ReS 2 , a layered two-dimensional material popular for its in-plane anisotropic properties, is emerging as one of the potential candidates for flexible electronics and ultrafast optical applications. It is an n-type semiconducting material having a layer independent bandgap of 1.55 eV. In this paper we have characterized the intrinsic electronic noise level of few-layer ReS 2 for the first time. Few-layer ReS 2 field effect transistor devices show a 1/f nature of noise for frequency ranging over three orders of magnitude. We have also observed that not only the electrical response of the material is anisotropic; the noise level is also dependent on direction. In fact the noise is found to be more sensitive towards the anisotropy. This fact has been explained by evoking the theory where the Hooge parameter is not a constant quantity, but has a distinct power law dependence on mobility along the two-axes direction. The anisotropy in 1/f noise measurement will pave the way to quantify the anisotropic nature of two-dimensional (2D) materials, which will be helpful for the design of low-noise transistors in future.

Probing in-plane anisotropy in few-layer ReS2 using low frequency noise measurement

NASA Astrophysics Data System (ADS)

Mitra, Richa; Jariwala, Bhakti; Bhattacharya, Arnab; Das, Anindya

2018-04-01

ReS2, a layered two-dimensional material popular for its in-plane anisotropic properties, is emerging as one of the potential candidates for flexible electronics and ultrafast optical applications. It is an n-type semiconducting material having a layer independent bandgap of 1.55 eV. In this paper we have characterized the intrinsic electronic noise level of few-layer ReS2 for the first time. Few-layer ReS2 field effect transistor devices show a 1/f nature of noise for frequency ranging over three orders of magnitude. We have also observed that not only the electrical response of the material is anisotropic; the noise level is also dependent on direction. In fact the noise is found to be more sensitive towards the anisotropy. This fact has been explained by evoking the theory where the Hooge parameter is not a constant quantity, but has a distinct power law dependence on mobility along the two-axes direction. The anisotropy in 1/f noise measurement will pave the way to quantify the anisotropic nature of two-dimensional (2D) materials, which will be helpful for the design of low-noise transistors in future.

Bi2S3microspheres grown on graphene sheets as low-cost counter-electrode materials for dye-sensitized solar cells.

PubMed

Li, Guang; Chen, Xiaoshuang; Gao, Guandao

2014-03-21

In this work, we synthesized 3D Bi2S3 microspheres comprised of nanorods grown along the (211) facet on graphene sheets by a solvothermal route, and investigated its catalytic activities through I-V curves and conversion efficiency tests as the CE in DSSCs. Although the (211) facet has a large band gap for a Bi2S3 semiconductor, owing to the introduction of graphene into the system, its short-circuit current density, open-circuit voltage, fill factor, and efficiency were Jsc = 12.2 mA cm(-2), Voc = 0.75 V, FF = 0.60, and η = 5.5%, respectively. By integrating it with graphene sheets, our material achieved the conversion efficiency of 5.5%, which is almost triple the best conversion efficiency value of the DSSCs with (211)-faceted 3D Bi2S3 without graphene (1.9%) reported in the latest literature. Since this conversion-efficient 3D material grown on the graphene sheets significantly improves its catalytic properties, it paves the way for designing and applying low-cost Pt-free CE materials in DSSC from inorganic nanostructures.

Nanowire-based thermoelectrics

NASA Astrophysics Data System (ADS)

Ali, Azhar; Chen, Yixi; Vasiraju, Venkata; Vaddiraju, Sreeram

2017-07-01

Research on thermoelectrics has seen a huge resurgence since the early 1990s. The ability of tuning a material’s electrical and thermal transport behavior upon nanostructuring has led to this revival. Nevertheless, thermoelectric performances of nanowires and related materials lag far behind those achieved with thin-film superlattices and quantum dot-based materials. This is despite the fact that nanowires offer many distinct advantages in enhancing the thermoelectric performances of materials. The simplicity of the strategy is the first and foremost advantage. For example, control of the nanowire diameters and their surface roughnesses will aid in enhancing their thermoelectric performances. Another major advantage is the possibility of obtaining high thermoelectric performances using simpler nanowire chemistries (e.g., elemental and binary compound semiconductors), paving the way for the fabrication of thermoelectric modules inexpensively from non-toxic elements. In this context, the topical review provides an overview of the current state of nanowire-based thermoelectrics. It concludes with a discussion of the future vision of nanowire-based thermoelectrics, including the need for developing strategies aimed at the mass production of nanowires and their interface-engineered assembly into devices. This eliminates the need for trial-and-error strategies and complex chemistries for enhancing the thermoelectric performances of materials.

Micro-dressing of a carbon nanotube array with MoS2 gauze

NASA Astrophysics Data System (ADS)

Lim, Sharon Xiaodai; Woo, Kah Whye; Ng, Junju; Lu, Junpeng; Kwang, Siu Yi; Zhang, Zheng; Tok, Eng Soon; Sow, Chorng-Haur

2015-10-01

Few-layer MoS2 film has been successfully assembled over an array of CNTs. Using different focused laser beams with different wavelengths, site selective patterning of either the MoS2 film or the supporting CNT array is achieved. This paves the way for applications and investigations into the fundamental properties of the hybrid MoS2/CNT material with a controlled architecture. Through Raman mapping, straining and electron doping of the MoS2 film as a result of interaction with the supporting CNT array are detected. The role of the MoS2 film was further emphasized with a lower work function being detected from Ultra-violet Photoelectron Spectrsocopy (UPS) measurements of the hybrid material, compared to the CNT array. The effect of the changes in the work function was illustrated through the optoelectronic behavior of the hybrid material. At 0 V, 3.49 nA of current is measured upon illuminating the sample with a broad laser beam emitting laser light with a wavelength of 532 nm. With a strong response to external irradiation of different wavelengths, and changes to the power of the excitation source, the hybrid material has shown potential for applications in optoelectronic devices.

Impact of some field factors on inhalation exposure levels to bitumen emissions during road paving operations.

PubMed

Deygout, François; Auburtin, Guy

2015-03-01

Variability in occupational exposure levels to bitumen emissions has been observed during road paving operations. This is due to recurrent field factors impacting the level of exposure experienced by workers during paving. The present study was undertaken in order to quantify the impact of such factors. Pre-identified variables currently encountered in the field were monitored and recorded during paving surveys, and were conducted randomly covering current applications performed by road crews. Multivariate variance analysis and regressions were then used on computerized field data. The statistical investigations were limited due to the relatively small size of the study (36 data). Nevertheless, the particular use of the step-wise regression tool enabled the quantification of the impact of several predictors despite the existing collinearity between variables. The two bitumen organic fractions (particulates and volatiles) are associated with different field factors. The process conditions (machinery used and delivery temperature) have a significant impact on the production of airborne particulates and explain up to 44% of variability. This confirms the outcomes described by previous studies. The influence of the production factors is limited though, and should be complemented by studying factors involving the worker such as work style and the mix of tasks. The residual volatile compounds, being part of the bituminous binder and released during paving operations, control the volatile emissions; 73% of the encountered field variability is explained by the composition of the bitumen batch. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

What Paves the Way to Conventional Language? The Predictive Value of Babble, Pointing, and Socioeconomic Status

ERIC Educational Resources Information Center

McGillion, Michelle; Herbert, Jane S.; Pine, Julian; Vihman, Marilyn; dePaolis, Rory; Keren-Portnoy, Tamar; Matthews, Danielle

2017-01-01

A child's first words mark the emergence of a uniquely human ability. Theories of the developmental steps that pave the way for word production have proposed that either vocal or gestural precursors are key. These accounts were tested by assessing the developmental synchrony in the onset of babbling, pointing, and word production for 46 infants…

A strategy to synthesize graphene-incorporated lignin polymer composite materials with uniform graphene dispersion and covalently bonded interface engineering

NASA Astrophysics Data System (ADS)

Wang, Mei; Duong, Le Dai; Ma, Yifei; Sun, Yan; Hong, Sung Yong; Kim, Ye Chan; Suhr, Jonghwan; Nam, Jae-Do

2017-08-01

Graphene-incorporated polymer composites have been demonstrated to have excellent mechanical and electrical properties. In the field of graphene-incorporated composite material synthesis, there are two main obstacles: Non-uniform dispersion of graphene filler in the matrix and weak interface bonding between the graphene filler and polymer matrix. To overcome these problems, we develop an in-situ polymerization strategy to synthesize uniformly dispersed and covalently bonded graphene/lignin composites. Graphene oxide (GO) was chemically modified by 4,4'-methylene diphenyl diisocyanate (MDI) to introduce isocyanate groups and form the urethane bonds with lignin macromonomers. Subsequential polycondensation reactions of lignin groups with caprolactone and sebacoyl chloride bring about a covalent network of modified GO and lignin-based polymers. The flexible and robust lignin polycaprolactone polycondensate/modified GO (Lig-GOm) composite membranes are achieved after vacuum filtration, which have tunable hydrophilicity and electrical resistance according to the contents of GOm. This research transforms lignin from an abundant biomass into film-state composite materials, paving a new way for the utilization of biomass wastes.

A One-Dimensional Organic Lead Chloride Hybrid with Excitation-Dependent Broadband Emissions

DOE PAGES

Wu, Guanhong; Zhou, Chenkun; Ming, Wenmei; ...

2018-05-23

Organic–inorganic metal halide hybrids have emerged as a new class of materials with fascinating optical and electronic properties. The exceptional structure tunability has enabled the development of materials with various dimensionalities at the molecular level, from three-dimensional (3D) to 2D, 1D, and 0D. Here, we report a new 1D lead chloride hybrid, C 4N 2H 14PbCl 4, which exhibits unusual inverse excitation-dependent broadband emission from bluish-green to yellow. Density functional theory calculations were performed to better understand the mechanism of this excitation-dependent broadband emission. This 1D hybrid material is found to have two emission centers, corresponding to the self-trapped excitonsmore » (STEs) and vacancy-bound excitons. The excitation-dependent emission is due to different populations of these two types of excitons generated at different excitation wavelengths. Furthermore, this work shows the rich chemistry and physics of organic–inorganic metal halide hybrids and paves the way to achieving novel light emitters with excitation-dependent broadband emissions at room temperature.« less

Highly Porous Thermoelectric Nanocomposites with LowThermalConductivityand High Figure of Merit from Large-Scale Solution-Synthesized Bi2Te2.5Se0.5HollowNanostructures

DOE PAGES

Xu, Biao; Ames Lab., Ames, IA; Feng, Tianli L.; ...

2017-01-12

In order to enhance the performance of thermoelectric materials and enable access to their widespread applications, it is beneficial yet challenging to synthesize hollow nanostructures in large quantities, with high porosity, low thermal conductivity (κ) and excellent figure of merit (z T). We report a scalable (ca. 11.0 g per batch) and low-temperature colloidal processing route for Bi 2Te 2.5Se 0.5 hollow nanostructures. They are sintered into porous, bulk nanocomposites (phi 10 mm×h 10 mm) with low κ (0.48 W m -1 K -1) and the highest z T (1.18) among state-of-the-art Bi 2Te 3-xSe x materilas. Additional benefits ofmore » the unprecedented low relative density (68–77 %) are the large demand reduction of raw materials and the improved portability. This method can be adopted to fabricate other porous phase-transition and thermoelectric chalcogenide materials and will pave the way for the implementation of hollow nanostructures in other fields.« less

Gate-Tunable WSe2/SnSe2 Backward Diode with Ultrahigh-Reverse Rectification Ratio.

PubMed

Murali, Krishna; Dandu, Medha; Das, Sarthak; Majumdar, Kausik

2018-02-14

Backward diodes conduct more efficiently in the reverse bias than in the forward bias, providing superior high-frequency response, temperature stability, radiation hardness, and 1/f noise performance than a conventional diode conducting in the forward direction. Here, we demonstrate a van der Waals material-based backward diode by exploiting the giant staggered band offsets of WSe 2 /SnSe 2 vertical heterojunction. The diode exhibits an ultrahigh-reverse rectification ratio (R) of ∼2.1 × 10 4 , and the same is maintained up to an unusually large bias of 1.5 V-outperforming existing backward diode reports using conventional bulk semiconductors as well as one- and two-dimensional materials by more than an order of magnitude while maintaining an impressive curvature coefficient (γ) of ∼37 V -1 . The transport mechanism in the diode is shown to be efficiently tunable by external gate and drain bias, as well as by the thickness of the WSe 2 layer and the type of metal contacts used. These results pave the way for practical electronic circuit applications using two-dimensional materials and their heterojunctions.

The Synthesis of LiMnxFe1−xPO4/C Cathode Material through Solvothermal Jointed with Solid-State Reaction

PubMed Central

He, Xiangming; Wang, Jixian; Dai, Zhongjia; Wang, Li; Tian, Guangyu

2016-01-01

LiMnxFe1−xPO4/C material has been synthesized through a facile solid-state reaction under the condition of carbon coating, using solvothermal-prepared LiMnPO4 and LiFePO4 as precursors and sucrose as a carbon resource. XRD and element distribution analysis reveal completed solid-state reaction of precursors. LiMnxFe1−xPO4/C composites inherit the morphology of precursors after heat treatment without obvious agglomeration and size increase. LiMnxFe1−xPO4 solid solution forms at low temperature around 350 °C, and Mn2+/Fe2+ diffuse completely within 1 h at 650 °C. The LiMnxFe1−xPO4/C (x < 0.8) composite exhibits a high-discharge capacity of over 120 mAh·g−1 (500 Wh·kg−1) at low C-rates. This paves a way to synthesize the crystal-optimized LiMnxFe1−xPO4/C materials for high performance Li-ion batteries. PMID:28773887

Fabrication of monolayer MoS2/rGO hybrids with excellent tribological performances through a surfactant-assisted hydrothermal route

NASA Astrophysics Data System (ADS)

Chen, Jinsuo; Xia, Yunfei; Yang, Jin; Chen, Beibei

2018-06-01

The extremely low friction between incommensurate two-dimensional (2D) atomic layers has recently attracted a great interest. Here, we demonstrated a promising surfactant-assisted strategy for the synthesis of MoS2/reduced graphene oxide (MoS2/rGO) hybrid materials with monolayer MoS2 and rGO, which exhibited excellent tribological metrics with a friction coefficient of ˜ 0.09 and a wear rate of ˜ 2.08 × 10-5 mm3/Nm in the ethanol dispersion. The incommensurate 2D atomic layer interface formed due to intrinsic lattice mismatch between MoS2 and graphene was thought to be responsible for the excellent lubricating performances. In addition to the benefits of unique hybrid structure, MoS2/rGO hybrids could also adsorb on metal surfaces and screen the metal-metal interaction to passivate the metal surfaces with a consequent reduction of corrosion wear during sliding. This work could pave a new pathway to design novel materials for pursuing excellent tribological properties by hybridizing different 2D atomic-layered materials.

Rational design of stealthy hyperuniform two-phase media with tunable order

NASA Astrophysics Data System (ADS)

DiStasio, Robert A.; Zhang, Ge; Stillinger, Frank H.; Torquato, Salvatore

2018-02-01

Disordered stealthy hyperuniform materials are exotic amorphous states of matter that have attracted recent attention because of their novel structural characteristics (hidden order at large length scales) and physical properties, including desirable photonic and transport properties. It is therefore useful to devise algorithms that enable one to design a wide class of such amorphous configurations at will. In this paper, we present several algorithms enabling the systematic identification and generation of discrete (digitized) stealthy hyperuniform patterns with a tunable degree of order, paving the way towards the rational design of disordered materials endowed with novel thermodynamic and physical properties. To quantify the degree of order or disorder of the stealthy systems, we utilize the discrete version of the τ order metric, which accounts for the underlying spatial correlations that exist across all relevant length scales in a given digitized two-phase (or, equivalently, a two-spin state) system of interest. Our results impinge on a myriad of fields, ranging from physics, materials science and engineering, visual perception, and information theory to modern data science.

Interface formation in monolayer graphene-boron nitride heterostructures.

PubMed

Sutter, P; Cortes, R; Lahiri, J; Sutter, E

2012-09-12

The ability to control the formation of interfaces between different materials has become one of the foundations of modern materials science. With the advent of two-dimensional (2D) crystals, low-dimensional equivalents of conventional interfaces can be envisioned: line boundaries separating different materials integrated in a single 2D sheet. Graphene and hexagonal boron nitride offer an attractive system from which to build such 2D heterostructures. They are isostructural, nearly lattice-matched, and isoelectronic, yet their different band structures promise interesting functional properties arising from their integration. Here, we use a combination of in situ microscopy techniques to study the growth and interface formation of monolayer graphene-boron nitride heterostructures on ruthenium. In a sequential chemical vapor deposition process, boron nitride grows preferentially at the edges of existing monolayer graphene domains, which can be exploited for synthesizing continuous 2D membranes of graphene embedded in boron nitride. High-temperature growth leads to intermixing near the interface, similar to interfacial alloying in conventional heterostructures. Using real-time microscopy, we identify processes that eliminate this intermixing and thus pave the way to graphene-boron nitride heterostructures with atomically sharp interfaces.

Ferroelectricity, Antiferroelectricity, and Ultrathin 2D Electron/Hole Gas in Multifunctional Monolayer MXene.

PubMed

Chandrasekaran, Anand; Mishra, Avanish; Singh, Abhishek Kumar

2017-05-10

The presence of ferroelectric polarization in 2D materials is extremely rare due to the effect of the surface depolarizing field. Here, we use first-principles calculations to show the largest out-of-plane polarization observed in a monolayer in functionalized MXenes (Sc 2 CO 2 ). The switching of polarization in this new class of ferroelectric materials occurs through a previously unknown intermediate antiferroelectric structure, thus establishing three states for applications in low-dimensional nonvolatile memory. We show that the armchair domain interface acts as an 1D metallic nanowire separating two insulating domains. In the case of the van der Waals bilayer we observe, interestingly, the presence of an ultrathin 2D electron/hole gas (2DEG) on the top/bottom layers, respectively, due to the redistrubution of charge carriers. The 2DEG is nondegenerate due to spin-orbit coupling, thus paving the way for spin-orbitronic devices. The coexistence of ferroelectricity, antiferroelectricity, 2DEG, and spin-orbit splitting in this system suggests that such 2D polar materials possess high potential for device application in a multitude of fields ranging from nanoelectronics to photovoltaics.

A One-Dimensional Organic Lead Chloride Hybrid with Excitation-Dependent Broadband Emissions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Guanhong; Zhou, Chenkun; Ming, Wenmei

Organic–inorganic metal halide hybrids have emerged as a new class of materials with fascinating optical and electronic properties. The exceptional structure tunability has enabled the development of materials with various dimensionalities at the molecular level, from three-dimensional (3D) to 2D, 1D, and 0D. Here, we report a new 1D lead chloride hybrid, C 4N 2H 14PbCl 4, which exhibits unusual inverse excitation-dependent broadband emission from bluish-green to yellow. Density functional theory calculations were performed to better understand the mechanism of this excitation-dependent broadband emission. This 1D hybrid material is found to have two emission centers, corresponding to the self-trapped excitonsmore » (STEs) and vacancy-bound excitons. The excitation-dependent emission is due to different populations of these two types of excitons generated at different excitation wavelengths. Furthermore, this work shows the rich chemistry and physics of organic–inorganic metal halide hybrids and paves the way to achieving novel light emitters with excitation-dependent broadband emissions at room temperature.« less

Photogating in Low Dimensional Photodetectors

PubMed Central

Fang, Hehai

2017-01-01

Abstract Low dimensional materials including quantum dots, nanowires, 2D materials, and so forth have attracted increasing research interests for electronic and optoelectronic devices in recent years. Photogating, which is usually observed in photodetectors based on low dimensional materials and their hybrid structures, is demonstrated to play an important role. Photogating is considered as a way of conductance modulation through photoinduced gate voltage instead of simply and totally attributing it to trap states. This review first focuses on the gain of photogating and reveals the distinction from conventional photoconductive effect. The trap‐ and hybrid‐induced photogating including their origins, formations, and characteristics are subsequently discussed. Then, the recent progress on trap‐ and hybrid‐induced photogating in low dimensional photodetectors is elaborated. Though a high gain bandwidth product as high as 109 Hz is reported in several cases, a trade‐off between gain and bandwidth has to be made for this type of photogating. The general photogating is put forward according to another three reported studies very recently. General photogating may enable simultaneous high gain and high bandwidth, paving the way to explore novel high‐performance photodetectors. PMID:29270342

A spatial-temporal method for assessing the energy balance dynamics of partially sealed surfaces.

NASA Astrophysics Data System (ADS)

Pipkins, Kyle; Kleinschmit, Birgit; Wessolek, Gerd

2017-04-01

The effects of different types of sealed surfaces on the surface energy balance have been well-studied in the past. However, these field studies typically aggregate these surfaces into continuous units. The proposed method seeks to disaggregate such surfaces into paving and seam areas using spatial methods, and to consider the temperature dynamics under wet and dry conditions between these two components. This experimental work is undertaken using a thermal camera to record a time series of images over two lysimeters with differing levels of surface sealing. The images are subsequently decomposed into component materials using object-based image analysis and compared on the basis of both the surface materials as well as the spatial configuration of materials. Finally, a surface energy balance method is used to estimate evaporation rates from the surfaces, both separately for the different surface components as well as using the total surface mean. Results are validated using the output of the weighing lysimeter. Our findings will determine whether the explicitly spatial method is an improvement over the mean aggregate method.

Printing and Folding: A Solution for High-Throughput Processing of Organic Thin-Film Thermoelectric Devices

PubMed Central

Mortazavinatanzi, Seyedmohammad; Rosendahl, Lasse

2018-01-01

Wearable electronics are rapidly expanding, especially in applications like health monitoring through medical sensors and body area networks (BANs). Thermoelectric generators (TEGs) have been the main candidate among the different types of energy harvesting methods for body-mounted or even implantable sensors. Introducing new semiconductor materials like organic thermoelectric materials and advancing manufacturing techniques are paving the way to overcome the barriers associated with the bulky and inflexible nature of the common TEGs and are making it possible to fabricate flexible and biocompatible modules. Yet, the lower efficiency of these materials in comparison with bulk-inorganic counterparts as well as applying them mostly in the form of thin layers on flexible substrates limits their applications. This research aims to improve the functionality of thin and flexible organic thermoelectric generators (OTEs) by utilizing a novel design concept inspired by origami. The effects of critical geometric parameters are investigated using COMSOL Multiphysics to further prove the concept of printing and folding as an approach for the system level optimization of printed thin film TEGs. PMID:29584634

Single-wall carbon nanotubes and graphene oxide-based saturable absorbers for low phase noise mode-locked fiber lasers

PubMed Central

Li, Xiaohui; Wu, Kan; Sun, Zhipei; Meng, Bo; Wang, Yonggang; Wang, Yishan; Yu, Xuechao; Yu, Xia; Zhang, Ying; Shum, Perry Ping; Wang, Qi Jie

2016-01-01

Low phase noise mode-locked fiber laser finds important applications in telecommunication, ultrafast sciences, material science, and biology, etc. In this paper, two types of carbon nano-materials, i.e. single-wall carbon nanotube (SWNT) and graphene oxide (GO), are investigated as efficient saturable absorbers (SAs) to achieve low phase noise mode-locked fiber lasers. Various properties of these wall-paper SAs, such as saturable intensity, optical absorption and degree of purity, are found to be key factors determining the performance of the ultrafast pulses. Reduced-noise femtosecond fiber lasers based on such carbon-based SAs are experimentally demonstrated, for which the phase noise has been reduced by more than 10 dB for SWNT SAs and 8 dB for GO SAs at 10 kHz. To the best of our knowledge, this is the first investigation on the relationship between different carbon material based SAs and the phase noise of mode-locked lasers. This work paves the way to generate high-quality low phase noise ultrashort pulses in passively mode-locked fiber lasers. PMID:27126900

Advanced Materials From Fungal Mycelium: Fabrication and Tuning of Physical Properties

NASA Astrophysics Data System (ADS)

Haneef, Muhammad; Ceseracciu, Luca; Canale, Claudio; Bayer, Ilker S.; Heredia-Guerrero, José A.; Athanassiou, Athanassia

2017-01-01

In this work is presented a new category of self-growing, fibrous, natural composite materials with controlled physical properties that can be produced in large quantities and over wide areas, based on mycelium, the main body of fungi. Mycelia from two types of edible, medicinal fungi, Ganoderma lucidum and Pleurotus ostreatus, have been carefully cultivated, being fed by two bio-substrates: cellulose and cellulose/potato-dextrose, the second being easier to digest by mycelium due to presence of simple sugars in its composition. After specific growing times the mycelia have been processed in order to cease their growth. Depending on their feeding substrate, the final fibrous structures showed different relative concentrations in polysaccharides, lipids, proteins and chitin. Such differences are reflected as alterations in morphology and mechanical properties. The materials grown on cellulose contained more chitin and showed higher Young’s modulus and lower elongation than those grown on dextrose-containing substrates, indicating that the mycelium materials get stiffer when their feeding substrate is harder to digest. All the developed fibrous materials were hydrophobic with water contact angles higher than 120°. The possibility of tailoring mycelium materials’ properties by properly choosing their nutrient substrates paves the way for their use in various scale applications.

The potential use of tar sand bitumen as paving asphalt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petersen, J.C.

1988-01-01

In this paper several research reports describing the preparation of potential paving asphalts from tar sand bitumen are reviewed and the results of the studies compared. The tar sand asphalts described in the studies were prepared from 1) hot water-recovered bitumen from deposits near San Luis Obispo, California (Edna deposits), and deposits near Vernal and Sunnyside, Utah; and 2) bitumen recovered from the Northwest Asphalt Ridge deposits near Vernal, Utah, by both in situ steamflood and in situ combustion recovery processes. Important properties of the tar sand asphalts compare favorably with those of specification petroleum asphalts. Laboratory data suggest thatmore » some tar sand asphalts may have superior aging characteristics and produce more water-resistant paving mixtures than typical petroleum asphalts.« less

A Synthetic Circuit for Mercury Bioremediation Using Self-Assembling Functional Amyloids.

PubMed

Tay, Pei Kun R; Nguyen, Peter Q; Joshi, Neel S

2017-10-20

Synthetic biology approaches to bioremediation are a key sustainable strategy to leverage the self-replicating and programmable aspects of biology for environmental stewardship. The increasing spread of anthropogenic mercury pollution into our habitats and food chains is a pressing concern. Here, we explore the use of programmed bacterial biofilms to aid in the sequestration of mercury. We demonstrate that by integrating a mercury-responsive promoter and an operon encoding a mercury-absorbing self-assembling extracellular protein nanofiber, we can engineer bacteria that can detect and sequester toxic Hg 2+ ions from the environment. This work paves the way for the development of on-demand biofilm living materials that can operate autonomously as heavy-metal absorbents.

Bismuth-induced Raman modes in GaP 1– xBi x

DOE PAGES

Christian, Theresa M.; Fluegel, Brian; Beaton, Daniel A.; ...

2016-09-02

Here, dilute bismide semiconductor alloys are a promising material platform for optoelectronic devices due to drastic impacts of bismuth on the electronic structure of the alloy. At the same time, the details of bismuth incorporation in the lattice are not fully understood. In this work, we conduct Raman scattering spectroscopy on GaP 1- xBi x epilayers grown by molecular beam epitaxy (MBE) and identify several bismuth-related Raman features including gap vibration modes at 296, 303, and 314 cm -1. This study paves the way for more detailed analysis of the local symmetry at bismuth incorporation sites in the dilute bismidemore » alloy regime.« less

Progress in the development of gelling agents for improved culturability of microorganisms

PubMed Central

Das, Nabajit; Tripathi, Naveen; Basu, Srijoni; Bose, Chandra; Maitra, Susmit; Khurana, Sukant

2015-01-01

Gelling agents are required for formulating both solid and semisolid media, vital for the isolation of microorganisms. Gelatin was the first gelling agent to be discovered but it soon paved the way for agar, which has far superior material qualities. Source depletion, issues with polymerase-chain-reaction and inability to sustain extermophiles etc., necessitate the need of other gelling agents. Many new gelling agents, such as xantham gum, gellan gum, carrageenan, isubgol, and guar gum have been formulated, raising the hopes for the growth of previously unculturable microorganisms. We evaluate the progress in the development of gelling agents, with the hope that our synthesis would help accelerate research in the field. PMID:26257708

Controlled Synthesis of Atomically Layered Hexagonal Boron Nitride via Chemical Vapor Deposition.

PubMed

Liu, Juanjuan; Kutty, R Govindan; Liu, Zheng

2016-11-29

Hexagonal boron nitrite (h-BN) is an attractive material for many applications including electronics as a complement to graphene, anti-oxidation coatings, light emitters, etc. However, the synthesis of high-quality h-BN is still a great challenge. In this work, via controlled chemical vapor deposition, we demonstrate the synthesis of h-BN films with a controlled thickness down to atomic layers. The quality of as-grown h-BN is confirmed by complementary characterizations including high-resolution transition electron microscopy, atomic force microscopy, Raman spectroscopy and X-ray photo-electron spectroscopy. This work will pave the way for production of large-scale and high-quality h-BN and its applications as well.

Direct patterning of organic conductors on knitted textiles for long-term electrocardiography

PubMed Central

Takamatsu, Seiichi; Lonjaret, Thomas; Crisp, Dakota; Badier, Jean-Michel; Malliaras, George G.; Ismailova, Esma

2015-01-01

Wearable sensors are receiving a great deal of attention as they offer the potential to become a key technological tool for healthcare. In order for this potential to come to fruition, new electroactive materials endowing high performance need to be integrated with textiles. Here we present a simple and reliable technique that allows the patterning of conducting polymers on textiles. Electrodes fabricated using this technique showed a low impedance contact with human skin, were able to record high quality electrocardiograms at rest, and determine heart rate even when the wearer was in motion. This work paves the way towards imperceptible electrophysiology sensors for human health monitoring. PMID:26446346

Weathering of radiocaesium contamination on urban streets, walls and roofs.

PubMed

Andersson, K G; Roed, J; Fogh, C L

2002-01-01

Recent investigations in Russia have emphasised the significance of dose contributions from contamination on urban streets and roof pavings, and, typically to a lesser extent, walls in the urban environment. The crucial factor determining the magnitude of these contributions is the retention of the contamination by the different types of urban surface. Since the Chernobyl accident, a series of long-term field studies has been carried out on urban streets, walls and roofs, to examine the weathering processes of 137Cs on the various surface types. The derived time-functions are applied to estimate resultant long-term doses to inhabitants of an urban centre. The paper highlights the effect on caesium retention of surface material characteristics.

Spatial transcriptomics: paving the way for tissue-level systems biology.

PubMed

Moor, Andreas E; Itzkovitz, Shalev

2017-08-01

The tissues in our bodies are complex systems composed of diverse cell types that often interact in highly structured repeating anatomical units. External gradients of morphogens, directional blood flow, as well as the secretion and absorption of materials by cells generate distinct microenvironments at different tissue coordinates. Such spatial heterogeneity enables optimized function through division of labor among cells. Unraveling the design principles that govern this spatial division of labor requires techniques to quantify the entire transcriptomes of cells while accounting for their spatial coordinates. In this review we describe how recent advances in spatial transcriptomics open the way for tissue-level systems biology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Plasmon confinement in fractal quantum systems

NASA Astrophysics Data System (ADS)

Westerhout, Tom; van Veen, Edo; Katsnelson, Mikhail I.; Yuan, Shengjun

2018-05-01

Recent progress in the fabrication of materials has made it possible to create arbitrary nonperiodic two-dimensional structures in the quantum plasmon regime. This paves the way for exploring the quantum plasmonic properties of electron gases in complex geometries. In this work we study systems with a fractal dimension. We calculate the full dielectric functions of two prototypical fractals with different ramification numbers, namely the Sierpinski carpet and gasket. We show that the Sierpinski carpet has a dispersion comparable to a square lattice, but the Sierpinski gasket features highly localized plasmon modes with a flat dispersion. This strong plasmon confinement in finitely ramified fractals can provide a novel setting for manipulating light at the quantum level.

Quantifying the Beauty of Words: A Neurocognitive Poetics Perspective

PubMed Central

Jacobs, Arthur M.

2017-01-01

In this paper I would like to pave the ground for future studies in Computational Stylistics and (Neuro-)Cognitive Poetics by describing procedures for predicting the subjective beauty of words. A set of eight tentative word features is computed via Quantitative Narrative Analysis (QNA) and a novel metric for quantifying word beauty, the aesthetic potential is proposed. Application of machine learning algorithms fed with this QNA data shows that a classifier of the decision tree family excellently learns to split words into beautiful vs. ugly ones. The results shed light on surface and semantic features theoretically relevant for affective-aesthetic processes in literary reading and generate quantitative predictions for neuroaesthetic studies of verbal materials. PMID:29311877

Quantifying the Beauty of Words: A Neurocognitive Poetics Perspective.

PubMed

Jacobs, Arthur M

2017-01-01

In this paper I would like to pave the ground for future studies in Computational Stylistics and (Neuro-)Cognitive Poetics by describing procedures for predicting the subjective beauty of words. A set of eight tentative word features is computed via Quantitative Narrative Analysis (QNA) and a novel metric for quantifying word beauty, the aesthetic potential is proposed. Application of machine learning algorithms fed with this QNA data shows that a classifier of the decision tree family excellently learns to split words into beautiful vs. ugly ones. The results shed light on surface and semantic features theoretically relevant for affective-aesthetic processes in literary reading and generate quantitative predictions for neuroaesthetic studies of verbal materials.

Fabrication of composite films containing zirconia and cationic polyelectrolytes.

PubMed

Pang, Xin; Zhitomirsky, Igor

2004-03-30

Composite films were prepared by electrophoretic deposition of poly(ethylenimine) or poly(allylamine hydrochloride) combined with cathodic precipitation of zirconia. Films of up to several micrometers thick were obtained on Ni, Pt, stainless-steel, graphite, and carbon-felt substrates. When the concentration of polyelectrolytes in solutions and the deposition time were varied, the amount of the deposited material and its composition can be varied. The electrochemical intercalation of yttria-stabilized zirconia particles into the composite films has been demonstrated. Obtained results pave the way for the electrodeposition of other polymer-ceramic composites. The deposits were studied by thermogravimetric analysis, X-ray diffraction analysis, scanning electron microscopy, and atomic force microscopy. The mechanisms of deposition are discussed.

Current Trends in Nanomaterial-Based Amperometric Biosensors

PubMed Central

Hayat, Akhtar; Catanante, Gaëlle; Marty, Jean Louis

2014-01-01

The last decade has witnessed an intensive research effort in the field of electrochemical sensors, with a particular focus on the design of amperometric biosensors for diverse analytical applications. In this context, nanomaterial integration in the construction of amperometric biosensors may constitute one of the most exciting approaches. The attractive properties of nanomaterials have paved the way for the design of a wide variety of biosensors based on various electrochemical detection methods to enhance the analytical characteristics. However, most of these nanostructured materials are not explored in the design of amperometric biosensors. This review aims to provide insight into the diverse properties of nanomaterials that can be possibly explored in the construction of amperometric biosensors. PMID:25494347

Navigating at Will on the Water Phase Diagram

NASA Astrophysics Data System (ADS)

Pipolo, S.; Salanne, M.; Ferlat, G.; Klotz, S.; Saitta, A. M.; Pietrucci, F.

2017-12-01

Despite the simplicity of its molecular unit, water is a challenging system because of its uniquely rich polymorphism and predicted but yet unconfirmed features. Introducing a novel space of generalized coordinates that capture changes in the topology of the interatomic network, we are able to systematically track transitions among liquid, amorphous, and crystalline forms throughout the whole phase diagram of water, including the nucleation of crystals above and below the melting point. Our approach, based on molecular dynamics and enhanced sampling or free energy calculation techniques, is not specific to water and could be applied to very different structural phase transitions, paving the way towards the prediction of kinetic routes connecting polymorphic structures in a range of materials.

Antiferroelectric Materials, Applications and Recent Progress on Multiferroic Heterostructures

NASA Astrophysics Data System (ADS)

Zhou, Ziyao; Yang, Qu; Liu, Ming; Zhang, Zhiguo; Zhang, Xinyang; Sun, Dazhi; Nan, Tianxiang; Sun, Nianxiang; Chen, Xing

2015-04-01

Antiferroelectric (AFE) materials with adjacent dipoles oriented in antiparallel directions have a double polarization hysteresis loops. An electric field (E-field)-induced AFE-ferroelectric (FE) phase transition takes place in such materials, leading to a large lattice strain and energy change. The high dielectric constant and the distinct phase transition in AFE materials provide great opportunities for the realization of energy storage devices like super-capacitors and energy conversion devices such as AFE MEMS applications. Lots of work has been done in this field since 60-70 s. Recently, the strain tuning of the spin, charge and orbital orderings and their interactions in complex oxides and multiferroic heterostructures have received great attention. In these systems, a single control parameter of lattice strain is used to control lattice-spin, lattice-phonon, and lattice-charge interactions and tailor properties or create a transition between distinct magnetic/electronic phases. Due to the large strain/stress arising from the phase transition, AFE materials are great candidates for integrating with ferromagnetic (FM) materials to realize in situ manipulation of magnetism and lattice-ordered parameters by voltage. In this paper, we introduce the AFE material and it's applications shortly and then review the recent progress in AFEs based on multiferroic heterostructures. These new multiferroic materials could pave a new way towards next generation light, compact, fast and energy efficient voltage tunable RF/microwave, spintronic and memory devices promising approaches to in situ manipulation of lattice-coupled order parameters is to grow epitaxial oxide films on FE/ferroelastic substrates.

An Investigation of CTOL Dual-Mode PAVE Concepts

NASA Technical Reports Server (NTRS)

Marchman, James F., III; Interatep, Nanyaporn; Skelton, Eugene; Mason, William H.

2002-01-01

A study was conducted to assess the feasibility of the dual-mode concept for a personal air vehicle, to determine how constraints differ between the dual-mode concept and a Conventional Takeoff and Landing (CTOL) general aviation aircraft, to recommend a dual-mode vehicle concept, and to recommend areas where further research can contribute to the successful development of a viable PAVE vehicle design.

Investigating nanohybrid material based on 3D CNTs@Cu nanoparticle composite and imprinted polymer for highly selective detection of chloramphenicol.

PubMed

Munawar, Anam; Tahir, Muhammad Ali; Shaheen, Ayesha; Lieberzeit, Peter A; Khan, Waheed S; Bajwa, Sadia Z

2018-01-15

Nanotechnology holds great promise for the fabrication of versatile materials that can be used as sensor platforms for the highly selective detection of analytes. In this research article we report a new nanohybrid material, where 3D imprinted nanostructures are constructed. First, copper nanoparticles are deposited on carbon nanotubes and then a hybrid structure is formed by coating molecularly imprinted polymer on 3D CNTs@Cu NPs; and a layer by layer assembly is achieved. SEM and AFM revealed the presence of Cu NPs (100-500nm) anchored along the whole length of CNTs, topped with imprinted layer. This material was applied to fabricate an electrochemical sensor to monitor a model veterinary drug, chloramphenicol. The high electron transfer ability and conductivity of the prepared material produced sensitive response, whereas, molecular imprinting produces selectivity towards drug detection. The sensor responses were found concentration dependent and the detection limit was calculated to be 10μM (S/N=3). Finally, we showed how changing the polymer composition, the extent of cross linking, and sensor layer thickness greatly affects the number of binding sites for the recognition of drug. This work paves the way to build variants of 3D imprinted materials for the detection of other kinds of biomolecules and antibiotics. Copyright © 2017 Elsevier B.V. All rights reserved.

Breakable mesoporous silica nanoparticles for targeted drug delivery

NASA Astrophysics Data System (ADS)

Maggini, Laura; Cabrera, Ingrid; Ruiz-Carretero, Amparo; Prasetyanto, Eko A.; Robinet, Eric; de Cola, Luisa

2016-03-01

``Pop goes the particle''. Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery.``Pop goes the particle''. Here we report on the preparation of redox responsive mesoporous organo-silica nanoparticles containing disulfide (S-S) bridges (ss-NPs) that, even upon the exohedral grafting of targeting ligands, retained their ability to undergo structural degradation, and increase their local release activity when exposed to a reducing agent. This degradation could be observed also inside glioma C6 cancer cells. Moreover, when anticancer drug-loaded pristine and derivatized ss-NPs were fed to glioma C6 cells, the responsive hybrids were more effective in their cytotoxic action compared to non-breakable particles. The possibility of tailoring the surface functionalization of this hybrid, yet preserving its self-destructive behavior and enhanced drug delivery properties, paves the way for the development of effective biodegradable materials for in vivo targeted drug delivery. Electronic supplementary information (ESI) available: Full experimental procedures, additional SEM and TEM images of particles, complete UV-Vis and PL-monitored characterization of the breakdown of the particles, SAXS, N2 adsorption, cytotoxicity assays. See DOI: 10.1039/c5nr09112h

Carbon nanotubes for stabilization of nanostructured lipid particles

NASA Astrophysics Data System (ADS)

Gaunt, Nicholas P.; Patil-Sen, Yogita; Baker, Matthew J.; Kulkarni, Chandrashekhar V.

2014-12-01

Carbon nanotubes (CNTs) are increasingly studied for innovative biotechnological applications particularly where they are combined with essential biological materials like lipids. Lipids have been used earlier for enhancing the dispersibility of CNTs in aqueous solutions. Here we report a novel application of CNTs for stabilization of internally self-assembled nanostructured lipid particles of 2-5 μm size. Single-walled (pristine) as well as -OH and -COOH functionalized multi-walled CNTs were employed to produce nanostructured emulsions which stayed stable for months and could be re-dispersed after complete dehydration. Concentrations of CNTs employed for stabilization were very low; moreover CNTs were well-decorated with lipid molecules. These features contribute towards reducing their toxicity and improving biocompatibility for biomedical and pharmaceutical applications. Our approach paves the way for future development of combination therapies employing both CNTs and nanostructured lipid self-assembly together as carriers of different drugs.Carbon nanotubes (CNTs) are increasingly studied for innovative biotechnological applications particularly where they are combined with essential biological materials like lipids. Lipids have been used earlier for enhancing the dispersibility of CNTs in aqueous solutions. Here we report a novel application of CNTs for stabilization of internally self-assembled nanostructured lipid particles of 2-5 μm size. Single-walled (pristine) as well as -OH and -COOH functionalized multi-walled CNTs were employed to produce nanostructured emulsions which stayed stable for months and could be re-dispersed after complete dehydration. Concentrations of CNTs employed for stabilization were very low; moreover CNTs were well-decorated with lipid molecules. These features contribute towards reducing their toxicity and improving biocompatibility for biomedical and pharmaceutical applications. Our approach paves the way for future development of combination therapies employing both CNTs and nanostructured lipid self-assembly together as carriers of different drugs. Electronic supplementary information (ESI) available: Concentration series studies with Raman spectroscopy and small angle X-ray diffraction pattern for dry lipid and dehydrated CNT-lipid particles support the article. See DOI: 10.1039/c4nr05593d

3. "LAUNCH SILOS; AREA PAVING AND GRADING PLAN." Specifications No. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. "LAUNCH SILOS; AREA PAVING AND GRADING PLAN." Specifications No. ENG-04-353-59-73; Drawing No. 5841C-11; D.O. SERIES AW-1525/17; Stamped: RECORD DRAWING AS CONSTRUCTED. Below stamp: Contract No. 6601, Date 18 Sep 59. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Missile Silo Type, Test Area 1-100, northeast end of Test Area 1-100 Road, Boron, Kern County, CA

Installation Restoration Program (IRP). Operable Unit B1 Remedial Investigation/Feasibility Study

DTIC Science & Technology

1993-07-01

Alternative Evaluation Criteria ......................... 8-2 8-2 Remedial Alternative Evaluation Criteria Rating System ................ 8-3 8-3...ies, various technologies and process options relative numerical rating system was developed were identified and screened on the basis of (see Table 8-2...extensive paving and PCBs were found (north/central ditch). This storm drainage system , and because of the ditch was paved with asphalt in 1981; before

Block copolymer based composition and morphology control in nanostructured hybrid materials for energy conversion and storage: solar cells, batteries, and fuel cells.

PubMed

Orilall, M Christopher; Wiesner, Ulrich

2011-02-01

The development of energy conversion and storage devices is at the forefront of research geared towards a sustainable future. However, there are numerous issues that prevent the widespread use of these technologies including cost, performance and durability. These limitations can be directly related to the materials used. In particular, the design and fabrication of nanostructured hybrid materials is expected to provide breakthroughs for the advancement of these technologies. This tutorial review will highlight block copolymers as an emerging and powerful yet affordable tool to structure-direct such nanomaterials with precise control over structural dimensions, composition and spatial arrangement of materials in composites. After providing an introduction to materials design and current limitations, the review will highlight some of the most recent examples of block copolymer structure-directed nanomaterials for photovoltaics, batteries and fuel cells. In each case insights are provided into the various underlying fundamental chemical, thermodynamic and kinetic formation principles enabling general and relatively inexpensive wet-polymer chemistry methodologies for the efficient creation of multiscale functional materials. Examples include nanostructured ceramics, ceramic-carbon composites, ceramic-carbon-metal composites and metals with morphologies ranging from hexagonally arranged cylinders to three-dimensional bi-continuous cubic networks. The review ends with an outlook towards the synthesis of multicomponent and hierarchical multifunctional hybrid materials with different nano-architectures from self-assembly of higher order blocked macromolecules which may ultimately pave the way for the further development of energy conversion and storage devices.

Nanotechnology for Food Packaging and Food Quality Assessment.

PubMed

Rossi, Marco; Passeri, Daniele; Sinibaldi, Alberto; Angjellari, Mariglen; Tamburri, Emanuela; Sorbo, Angela; Carata, Elisabetta; Dini, Luciana

Nanotechnology has paved the way to innovative food packaging materials and analytical methods to provide the consumers with healthier food and to reduce the ecological footprint of the whole food chain. Combining antimicrobial and antifouling properties, thermal and mechanical protection, oxygen and moisture barrier, as well as to verify the actual quality of food, e.g., sensors to detect spoilage, bacterial growth, and to monitor incorrect storage conditions, or anticounterfeiting devices in food packages may extend the products shelf life and ensure higher quality of foods. Also the ecological footprint of food chain can be reduced by developing new completely recyclable and/or biodegradable packages from natural and eco-friendly resources. The contribution of nanotechnologies to these goals is reviewed in this chapter, together with a description of portable devices ("lab-on-chip," sensors, nanobalances, etc.) which can be used to assess the quality of food and an overview of regulations in force on food contact materials. © 2017 Elsevier Inc. All rights reserved.

Controlling the volatility of the written optical state in electrochromic DNA liquid crystals

NASA Astrophysics Data System (ADS)

Liu, Kai; Varghese, Justin; Gerasimov, Jennifer Y.; Polyakov, Alexey O.; Shuai, Min; Su, Juanjuan; Chen, Dong; Zajaczkowski, Wojciech; Marcozzi, Alessio; Pisula, Wojciech; Noheda, Beatriz; Palstra, Thomas T. M.; Clark, Noel A.; Herrmann, Andreas

2016-05-01

Liquid crystals are widely used in displays for portable electronic information display. To broaden their scope for other applications like smart windows and tags, new material properties such as polarizer-free operation and tunable memory of a written state become important. Here, we describe an anhydrous nanoDNA-surfactant thermotropic liquid crystal system, which exhibits distinctive electrically controlled optical absorption, and temperature-dependent memory. In the liquid crystal isotropic phase, electric field-induced colouration and bleaching have a switching time of seconds. Upon transition to the smectic liquid crystal phase, optical memory of the written state is observed for many hours without applied voltage. The reorientation of the DNA-surfactant lamellar layers plays an important role in preventing colour decay. Thereby, the volatility of optoelectronic state can be controlled simply by changing the phase of the material. This research may pave the way for developing a new generation of DNA-based, phase-modulated, photoelectronic devices.

Ultrafast electron diffraction and electron microscopy: present status and future prospects

NASA Astrophysics Data System (ADS)

Ishchenko, A. A.; Aseyev, S. A.; Bagratashvili, V. N.; Panchenko, V. Ya; Ryabov, E. A.

2014-07-01

Acting as complementary research tools, high time-resolved spectroscopy and diffractometry techniques proceeding from various physical principles open up new possibilities for studying matter with necessary integration of the 'structure-dynamics-function' triad in physics, chemistry, biology and materials science. Since the 1980s, a new field of research has started at the leading research laboratories, aimed at developing means of filming the coherent dynamics of nuclei in molecules and fast processes in biological objects ('atomic and molecular movies'). The utilization of ultrashort laser pulse sources has significantly modified traditional electron beam approaches to and provided high space-time resolution for the study of materials. Diffraction methods using frame-by-frame filming and the development of the main principles of the study of coherent dynamics of atoms have paved the way to observing wave packet dynamics, the intermediate states of reaction centers, and the dynamics of electrons in molecules, thus allowing a transition from the kinetics to the dynamics of the phase trajectories of molecules in the investigation of chemical reactions.

Rapid epitaxy-free graphene synthesis on silicidated polycrystalline platinum

PubMed Central

Babenko, Vitaliy; Murdock, Adrian T.; Koós, Antal A.; Britton, Jude; Crossley, Alison; Holdway, Philip; Moffat, Jonathan; Huang, Jian; Alexander-Webber, Jack A.; Nicholas, Robin J.; Grobert, Nicole

2015-01-01

Large-area synthesis of high-quality graphene by chemical vapour deposition on metallic substrates requires polishing or substrate grain enlargement followed by a lengthy growth period. Here we demonstrate a novel substrate processing method for facile synthesis of mm-sized, single-crystal graphene by coating polycrystalline platinum foils with a silicon-containing film. The film reacts with platinum on heating, resulting in the formation of a liquid platinum silicide layer that screens the platinum lattice and fills topographic defects. This reduces the dependence on the surface properties of the catalytic substrate, improving the crystallinity, uniformity and size of graphene domains. At elevated temperatures growth rates of more than an order of magnitude higher (120 μm min−1) than typically reported are achieved, allowing savings in costs for consumable materials, energy and time. This generic technique paves the way for using a whole new range of eutectic substrates for the large-area synthesis of 2D materials. PMID:26175062

Zero-field edge plasmons in a magnetic topological insulator [Zero-field edge magnetoplasmons in a magnetic topological insulator

DOE PAGES

Mahoney, Alice C.; Colless, James I.; Peeters, Lucas; ...

2017-11-28

Incorporating ferromagnetic dopants into three-dimensional topological insulator thin films has recently led to the realisation of the quantum anomalous Hall effect. These materials are of great interest since they may support electrical currents that flow without resistance, even at zero magnetic field. To date, the quantum anomalous Hall effect has been investigated using low-frequency transport measurements. However, transport results can be difficult to interpret due to the presence of parallel conductive paths, or because additional non-chiral edge channels may exist. Here we move beyond transport measurements by probing the microwave response of a magnetised disk of Cr-(Bi,Sb) 2Te 3. Wemore » identify features associated with chiral edge plasmons, a signature that robust edge channels are intrinsic to this material system. Finally, our results provide a measure of the velocity of edge excitations without contacting the sample, and pave the way for an on-chip circuit element of practical importance: the zero-field microwave circulator.« less

All Carbon-Based Photodetectors: An eminent integration of graphite quantum dots and two dimensional graphene

PubMed Central

Cheng, Shih-Hao; Weng, Tong-Min; Lu, Meng-Lin; Tan, Wei-Chun; Chen, Ju-Ying; Chen, Yang-Fang

2013-01-01

Photodetectors with ultrahigh sensitivity based on the composite made with all carbon-based materials consisting of graphite quantum dots (QDs), and two dimensional graphene crystal have been demonstrated. Under light illumination, remarkably, a photocurrent responsivity up to 4 × 107 AW−1 can be obtained. The underlying mechanism is attributed to the spatial separation of photogenerated electrons and holes due to the charge transfer caused by the appropriate band alignment across the interface between graphite QDs and graphene. Besides, the large absorptivity of graphite QDs and the excellent conductivity of the graphene sheet also play significant roles. Our result therefore demonstrates an outstanding illustration for the integration of the distinct properties of nanostructured carbon materials with different dimensionalities to achieve highly efficient devices. Together with the associated mechanism, it paves a valuable step for the further development of all carbon-based, cheap, and non-toxic optoelectronics devices with excellent performance. PMID:24045846

Infrared fingerprints of few-layer black phosphorus

PubMed Central

Zhang, Guowei; Huang, Shenyang; Chaves, Andrey; Song, Chaoyu; Özçelik, V. Ongun; Low, Tony; Yan, Hugen

2017-01-01

Black phosphorus is an infrared layered material. Its bandgap complements other widely studied two-dimensional materials: zero-gap graphene and visible/near-infrared gap transition metal dichalcogenides. Although highly desirable, a comprehensive infrared characterization is still lacking. Here we report a systematic infrared study of mechanically exfoliated few-layer black phosphorus, with thickness ranging from 2 to 15 layers and photon energy spanning from 0.25 to 1.36 eV. Each few-layer black phosphorus exhibits a thickness-dependent unique infrared spectrum with a series of absorption resonances, which reveals the underlying electronic structure evolution and serves as its infrared fingerprints. Surprisingly, unexpected absorption features, which are associated with the forbidden optical transitions, have been observed. Furthermore, we unambiguously demonstrate that controllable uniaxial strain can be used as a convenient and effective approach to tune the electronic structure of few-layer black phosphorus. Our study paves the way for black phosphorus applications in infrared photonics and optoelectronics. PMID:28059084

Biomimetic, Strong, Tough, and Self-Healing Composites Using Universal Sealant-Loaded, Porous Building Blocks.

PubMed

Hwang, Sung Hoon; Miller, Joseph B; Shahsavari, Rouzbeh

2017-10-25

Many natural materials, such as nacre and dentin, exhibit multifunctional mechanical properties via structural interplay between compliant and stiff constituents arranged in a particular architecture. Herein, we present, for the first time, the bottom-up synthesis and design of strong, tough, and self-healing composite using simple but universal spherical building blocks. Our composite system is composed of calcium silicate porous nanoparticles with unprecedented monodispersity over particle size, particle shape, and pore size, which facilitate effective loading and unloading with organic sealants, resulting in 258% and 307% increases in the indentation hardness and elastic modulus of the compacted composite. Furthermore, heating the damaged composite triggers the controlled release of the nanoconfined sealant into the surrounding area, enabling moderate recovery in strength and toughness. This work paves the path towards fabricating a novel class of biomimetic composites using low-cost spherical building blocks, potentially impacting bone-tissue engineering, insulation, refractory and constructions materials, and ceramic matrix composites.

Hydrophilicity Reinforced Adhesion of Anodic Alumina Oxide Template Films to Conducting Substrates for Facile Fabrication of Highly Ordered Nanorod Arrays.

PubMed

Wang, Chuanju; Wang, Guiqiang; Yang, Rui; Sun, Xiangyu; Ma, Hui; Sun, Shuqing

2017-01-17

Arrays of ordered nanorods are of special interest in many fields. However, it remains challenging to obtain such arrays on conducting substrates in a facile manner. In this article, we report the fabrication of highly ordered and vertically standing nanorod arrays of both metals and semiconductors on Au films and indium tin oxide glass substrates without an additional layering. In this approach, following the simple hydrophilic treatment of an anodic aluminum oxide (AAO) membrane and conducting substrates, the AAO membrane was transferred onto the modified substrates with excellent adhesion. Subsequently, nanorod arrays of various materials were electrodeposited on the conducting substrates directly. This method avoids any expensive and tedious lithographic and ion milling process, which provides a simple yet robust route to the fabrication of arrays of 1D materials with high aspect ratio on conducting substrates, which shall pave the way for many practical applications in a range of fields.

Forming free and ultralow-power erase operation in atomically crystal TiO2 resistive switching

NASA Astrophysics Data System (ADS)

Dai, Yawei; Bao, Wenzhong; Hu, Linfeng; Liu, Chunsen; Yan, Xiao; Chen, Lin; Sun, Qingqing; Ding, Shijin; Zhou, Peng; Zhang, David Wei

2017-06-01

Two-dimensional layered materials (2DLMs) have attracted broad interest from fundamental sciences to industrial applications. Their applications in memory devices have been demonstrated, yet much still remains to explore optimal materials and device structure for practical application. In this work, a forming-free, bipolar resistive switching behavior are demonstrated in 2D TiO2-based resistive random access memory (RRAM). Physical adsorption method is adopted to achieve high quality, continuous 2D TiO2 network efficiently. The 2D TiO2 RRAM devices exhibit superior properties such as fast switching capability (20 ns of erase operation) and extremely low erase energy consumption (0.16 fJ). Furthermore, the resistive switching mechanism is attributed to the formation and rupture of oxygen vacancies-based percolation path in 2D TiO2 crystals. Our results pave the way for the implementation of high performance 2DLMs-based RRAM in the next generation non-volatile memory (NVM) application.

A framework for the damage evaluation of acoustic emission signals through Hilbert-Huang transform

NASA Astrophysics Data System (ADS)

Siracusano, Giulio; Lamonaca, Francesco; Tomasello, Riccardo; Garescì, Francesca; Corte, Aurelio La; Carnì, Domenico Luca; Carpentieri, Mario; Grimaldi, Domenico; Finocchio, Giovanni

2016-06-01

The acoustic emission (AE) is a powerful and potential nondestructive testing method for structural monitoring in civil engineering. Here, we show how systematic investigation of crack phenomena based on AE data can be significantly improved by the use of advanced signal processing techniques. Such data are a fundamental source of information that can be used as the basis for evaluating the status of the material, thereby paving the way for a new frontier of innovation made by data-enabled analytics. In this article, we propose a framework based on the Hilbert-Huang Transform for the evaluation of material damages that (i) facilitates the systematic employment of both established and promising analysis criteria, and (ii) provides unsupervised tools to achieve an accurate classification of the fracture type, the discrimination between longitudinal (P-) and traversal (S-) waves related to an AE event. The experimental validation shows promising results for a reliable assessment of the health status through the monitoring of civil infrastructures.

Novel p-n heterojunction copper phosphide/cuprous oxide photocathode for solar hydrogen production.

PubMed

Chen, Ying-Chu; Chen, Zhong-Bo; Hsu, Yu-Kuei

2018-08-01

A Copper phosphide (Cu 3 P) micro-rod (MR) array, with coverage by an n-Cu 2 O thin layer by electrodeposition as a photocathode, has been directly fabricated on copper foil via simple electro-oxidation and phosphidation for photoelectrochemical (PEC) hydrogen production. The morphology, structure, and composition of the Cu 3 P/Cu 2 O heterostructure are systematically analyzed using a scanning electron microscope (SEM), X-ray diffraction and X-ray photoelectron spectra. The PEC measurements corroborate that the p-Cu 3 P/n-Cu 2 O heterostructural photocathode illustrates efficient charge separation and low charge transfer resistance to achieve the highest photocurrent of 430 μA cm -2 that is greater than other transition metal phosphide materials. In addition, a detailed energy diagram of the p-Cu 3 P/n-Cu 2 O heterostructure was investigated using Mott-Schottky analysis. Our study paves the way to explore phosphide-based materials in a new class for solar energy applications. Copyright © 2018 Elsevier Inc. All rights reserved.

ZnO template strategy for the synthesis of 3D interconnected graphene nanocapsules from coal tar pitch as supercapacitor electrode materials

NASA Astrophysics Data System (ADS)

He, Xiaojun; Li, Xiaojing; Ma, Hao; Han, Jiufeng; Zhang, Hao; Yu, Chang; Xiao, Nan; Qiu, Jieshan

2017-02-01

3D interconnected graphene nanocapsules (GNCs) were prepared from diverse aromatic hydrocarbons by a nano-ZnO-template strategy coupled with in-situ KOH activation technique. The as-made graphene networks feature thin carbonaceous shells with well-balanced micropores and mesopores. Such 3D porous networks provide freeways for good electron conduction, short pores for ion fast transport, and abundant micropores for ion adsorption. As the electrodes in supercapacitors, the unique 3D GNCs show a high capacitance of 277 F g-1 at 0.05 A g-1, a good rate performance of 194 F g-1 at 20 A g-1, and an excellent cycle stability with over 97.4% capacitance retention after 15000 cycles in 6 M KOH electrolyte. This synthesis strategy paves a universal way for mass production of 3D graphene materials from diverse aromatic hydrocarbon sources including coal tar pitch and petroleum pitch for high performance supercapacitors as well as support and sorbent.

Sol-gel spin coated well adhered MoO3 thin films as an alternative counter electrode for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Mutta, Geeta R.; Popuri, Srinivasa R.; Wilson, John I. B.; Bennett, Nick S.

2016-11-01

In this work, we aim to develop a viable, inexpensive and non-toxic material for counter electrodes in dye sensitized solar cells (DSSCs). We employed an ultra-simple synthesis process to deposit MoO3 thin films at low temperature by sol-gel spin coating technique. These MoO3 films showed good transparency. It is predicted that there will be 150 times reduction of precursors cost by realizing MoO3 thin films as a counter electrode in DSSCs compared to commercial Pt. We achieved a device efficiency of about 20 times higher than that of the previous reported values. In summary we develop a simple low cost preparation of MoO3 films with an easily scaled up process along with good device efficiency. This work encourages the development of novel and relatively new materials and paves the way for massive reduction of industrial costs which is a prime step for commercialization of DSSCs.

Controlling the strontium-doping in calcium phosphate microcapsules through yeast-regulated biomimetic mineralization.

PubMed

Huang, Miaojun; Li, Tianjie; Pan, Ting; Zhao, Naru; Yao, Yongchang; Zhai, Zhichen; Zhou, Jiaan; Du, Chang; Wang, Yingjun

2016-10-01

Yeast cells have controllable biosorption on metallic ions during metabolism. However, few studies were dedicated to using yeast-regulated biomimetic mineralization process to control the strontium-doped positions in calcium phosphate microcapsules. In this study, the yeast cells were allowed to pre-adsorb strontium ions metabolically and then served as sacrificing template for the precipitation and calcination of mineral shell. The pre-adsorption enabled the microorganism to enrich of strontium ions into the inner part of the microcapsules, which ensured a slow-release profile of the trace element from the microcapsule. The co-culture with human marrow stromal cells showed that gene expressions of alkaline phosphatase and Collagen-I were promoted. The promotion of osteogenic differentiation was further confirmed in the 3D culture of cell-material complexes. The strategy using living microorganism as 'smart doping apparatus' to control incorporation of trace element into calcium phosphate paved a pathway to new functional materials for hard tissue regeneration.

Soft-Templating Synthesis of N-Doped Mesoporous Carbon Nanospheres for Enhanced Oxygen Reduction Reaction.

PubMed

Bayatsarmadi, Bita; Zheng, Yao; Jaroniec, Mietek; Qiao, Shi Zhang

2015-07-01

The development of ordered mesoporous carbon materials with controllable structures and improved physicochemical properties by doping heteroatoms such as nitrogen into the carbon framework has attracted a lot of attention, especially in relation to energy storage and conversion. Herein, a series of nitrogen-doped mesoporous carbon spheres (NMCs) was synthesized via a facile dual soft-templating procedure by tuning the nitrogen content and carbonization temperature. Various physical and (electro)chemical properties of the NMCs have been comprehensively investigated to pave the way for a feasible design of nitrogen-containing porous carbon materials. The optimized sample showed a favorable electrocatalytic activity as evidenced by a high kinetic current and positive onset potential for oxygen reduction reaction (ORR) due to its large surface area, high pore volume, good conductivity, and high nitrogen content, which make it a highly efficient ORR metal-free catalyst in alkaline solutions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zero-field edge plasmons in a magnetic topological insulator [Zero-field edge magnetoplasmons in a magnetic topological insulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahoney, Alice C.; Colless, James I.; Peeters, Lucas

Incorporating ferromagnetic dopants into three-dimensional topological insulator thin films has recently led to the realisation of the quantum anomalous Hall effect. These materials are of great interest since they may support electrical currents that flow without resistance, even at zero magnetic field. To date, the quantum anomalous Hall effect has been investigated using low-frequency transport measurements. However, transport results can be difficult to interpret due to the presence of parallel conductive paths, or because additional non-chiral edge channels may exist. Here we move beyond transport measurements by probing the microwave response of a magnetised disk of Cr-(Bi,Sb) 2Te 3. Wemore » identify features associated with chiral edge plasmons, a signature that robust edge channels are intrinsic to this material system. Finally, our results provide a measure of the velocity of edge excitations without contacting the sample, and pave the way for an on-chip circuit element of practical importance: the zero-field microwave circulator.« less

Cascaded emission of single photons from the biexciton in monolayered WSe2

PubMed Central

He, Yu-Ming; Iff, Oliver; Lundt, Nils; Baumann, Vasilij; Davanco, Marcelo; Srinivasan, Kartik; Höfling, Sven; Schneider, Christian

2016-01-01

Monolayers of transition metal dichalcogenide materials emerged as a new material class to study excitonic effects in solid state, as they benefit from enormous Coulomb correlations between electrons and holes. Especially in WSe2, sharp emission features have been observed at cryogenic temperatures, which act as single photon sources. Tight exciton localization has been assumed to induce an anharmonic excitation spectrum; however, the evidence of the hypothesis, namely the demonstration of a localized biexciton, is elusive. Here we unambiguously demonstrate the existence of a localized biexciton in a monolayer of WSe2, which triggers an emission cascade of single photons. The biexciton is identified by its time-resolved photoluminescence, superlinearity and distinct polarization in micro-photoluminescence experiments. We evidence the cascaded nature of the emission process in a cross-correlation experiment, which yields a strong bunching behaviour. Our work paves the way to a new generation of quantum optics experiments with two-dimensional semiconductors. PMID:27830703

Strategies towards controlling strain-induced mesoscopic phase separation in manganite thin films

NASA Astrophysics Data System (ADS)

Habermeier, H.-U.

2008-10-01

Complex oxides represent a class of materials with a plethora of fascinating intrinsic physical functionalities. The intriguing interplay of charge, spin and orbital ordering in these systems superimposed by lattice effects opens a scientifically rewarding playground for both fundamental as well as application oriented research. The existence of nanoscale electronic phase separation in correlated complex oxides is one of the areas in this field whose impact on the current understanding of their physics and potential applications is not yet clear. In this paper this issue is treated from the point of view of complex oxide thin film technology. Commenting on aspects of complex oxide thin film growth gives an insight into the complexity of a reliable thin film technology for these materials. Exploring fundamentals of interfacial strain generation and strain accommodation paves the way to intentionally manipulate thin film properties. Furthermore, examples are given for an extrinsic continuous tuning of intrinsic electronic inhomogeneities in perovskite-type complex oxide thin films.

Black Phosphorus Quantum Dots for Hole Extraction of Typical Planar Hybrid Perovskite Solar Cells.

PubMed

Chen, Wei; Li, Kaiwen; Wang, Yao; Feng, Xiyuan; Liao, Zhenwu; Su, Qicong; Lin, Xinnan; He, Zhubing

2017-02-02

Black phosphorus, famous as two-dimensional (2D) materials, shows such excellent properties for optoelectronic devices such as tunable direct band gap, extremely high hole mobility (300-1000 cm 2 /(V s)), and so forth. In this Letter, facile processed black phosphorus quantum dots (BPQDs) were successfully applied to enhance hole extraction at the anode side of the typical p-i-n planar hybrid perovskite solar cells, which remarkably improved the performance of devices with photon conversion efficiency ramping up from 14.10 to 16.69%. Moreover, more detailed investigations by c-AFM, SKPM, SEM, hole-only devices, and photon physics measurements discover further the hole extraction effect and work mechanism of the BPQDs, such as nucleation assistance for the growth of large grain size perovskite crystals, fast hole extraction, more efficient hole transfer, and suppression of energy-loss recombination at the anode interface. This work definitely paves the way for discovering more and more 2D materials with high electronic properties to be used in photovoltaics and optoelectronics.

Ultralow-power and ultrafast all-optical tunable plasmon-induced transparency in metamaterials at optical communication range.

PubMed

Zhu, Yu; Hu, Xiaoyong; Fu, Yulan; Yang, Hong; Gong, Qihuang

2013-01-01

Actively all-optical tunable plasmon-induced transparency in metamaterials paves the way for achieving ultrahigh-speed quantum information processing chips. Unfortunately, up to now, very small experimental progress has been made for all-optical tunable plasmon-induced transparency in metamaterials in the visible and near-infrared range because of small third-order optical nonlinearity of conventional materials. The achieved operating pump intensity was as high as several GW/cm(2) order. Here, we report an ultralow-power and ultrafast all-optical tunable plasmon-induced transparency in metamaterials coated on polycrystalline indium-tin oxide layer at the optical communication range. Compared with previous reports, the threshold pump intensity is reduced by four orders of magnitude, while an ultrafast response time of picoseconds order is maintained. This work not only offers a way to constructing photonic materials with large nonlinearity and ultrafast response, but also opens up the possibility for realizing quantum solid chips and ultrafast integrated photonic devices based on metamaterials.

Ultralow-power and ultrafast all-optical tunable plasmon-induced transparency in metamaterials at optical communication range

PubMed Central

Zhu, Yu; Hu, Xiaoyong; Fu, Yulan; Yang, Hong; Gong, Qihuang

2013-01-01

Actively all-optical tunable plasmon-induced transparency in metamaterials paves the way for achieving ultrahigh-speed quantum information processing chips. Unfortunately, up to now, very small experimental progress has been made for all-optical tunable plasmon-induced transparency in metamaterials in the visible and near-infrared range because of small third-order optical nonlinearity of conventional materials. The achieved operating pump intensity was as high as several GW/cm2 order. Here, we report an ultralow-power and ultrafast all-optical tunable plasmon-induced transparency in metamaterials coated on polycrystalline indium-tin oxide layer at the optical communication range. Compared with previous reports, the threshold pump intensity is reduced by four orders of magnitude, while an ultrafast response time of picoseconds order is maintained. This work not only offers a way to constructing photonic materials with large nonlinearity and ultrafast response, but also opens up the possibility for realizing quantum solid chips and ultrafast integrated photonic devices based on metamaterials. PMID:23903825

Active hydrogen evolution through lattice distortion in metallic MoTe2

NASA Astrophysics Data System (ADS)

Seok, Jinbong; Lee, Jun-Ho; Cho, Suyeon; Ji, Byungdo; Kim, Hyo Won; Kwon, Min; Kim, Dohyun; Kim, Young-Min; Oh, Sang Ho; Wng Kim, Sung; Lee, Young Hee; Son, Young-Woo; Yang, Heejun

2017-06-01

Engineering surface atoms of transition metal dichalcogenides (TMDs) is a promising way to design catalysts for efficient electrochemical reactions including the hydrogen evolution reaction (HER). However, materials processing based on TMDs, such as vacancy creation or edge exposure, for active HER, has resulted in insufficient atomic-precision lattice homogeneity and a lack of clear understanding of HER over 2D materials. Here, we report a durable and effective HER at atomically defined reaction sites in 2D layered semimetallic MoTe2 with intrinsic turnover frequency (TOF) of 0.14 s-1 at 0 mV overpotential, which cannot be explained by the traditional volcano plot analysis. Unlike former electrochemical catalysts, the rate-determining step of the HER on the semimetallic MoTe2, hydrogen adsorption, drives Peierls-type lattice distortion that, together with a surface charge density wave, unexpectedly enhances the HER. The active HER using unique 2D features of layered TMDs enables an optimal design of electrochemical catalysts and paves the way for a hydrogen economy.

PAVE PAWS Early Warning Radar Operation Cape Cod Air Force Station, MA. Record of Decision

DTIC Science & Technology

2009-06-01

Electrical and Electronics Engineers (IEEE) C95.1-1999. Accordingly, the highest measurement was obtained directly in front of the feedhorn (i.e...waveform characterization of the Cape Cod AFS Pave PAWS radar. The data acquired during the Phase IV survey indicated that the electric fields produced...level observed among the ambient sites. During this survey, peak/average power density measurements and peak/average electric field measurements

Energy landscape paving simulations of the trp-cage protein.

PubMed

Schug, Alexander; Wenzel, Wolfgang; Hansmann, Ulrich H E

2005-05-15

We evaluate the efficiency of multiple variants of energy landscape paving in all-atom simulations of the trp-cage protein using a recently developed new force field. Especially, we introduce a temperature-free variant of the method and demonstrate that it allows a fast scanning of the energy landscape. Nativelike structures are found in less time than by other techniques. The sampled low-energy configurations indicate a funnel-like energy landscape.

ePave: A Self-Powered Wireless Sensor for Smart and Autonomous Pavement

PubMed Central

Xiao, Jian; Zou, Xiang

2017-01-01

“Smart Pavement” is an emerging infrastructure for various on-road applications in transportation and road engineering. However, existing road monitoring solutions demand a certain periodic maintenance effort due to battery life limits in the sensor systems. To this end, we present an end-to-end self-powered wireless sensor—ePave—to facilitate smart and autonomous pavements. The ePave system includes a self-power module, an ultra-low-power sensor system, a wireless transmission module and a built-in power management module. First, we performed an empirical study to characterize the piezoelectric module in order to optimize energy-harvesting efficiency. Second, we developed an integrated sensor system with the optimized energy harvester. An adaptive power knob is designated to adjust the power consumption according to energy budgeting. Finally, we intensively evaluated the ePave system in real-world applications to examine the system’s performance and explore the trade-off. PMID:28954430

Large n- and p-type thermoelectric power factors from doped semiconducting single-walled carbon nanotube thin films

DOE PAGES

MacLeod, Bradley A.; Stanton, Noah J.; Gould, Isaac E.; ...

2017-09-08

Lightweight, robust, and flexible single-walled carbon nanotube (SWCNT) materials can be processed inexpensively using solution-based techniques, similar to other organic semiconductors. In contrast to many semiconducting polymers, semiconducting SWCNTs (s-SWCNTs) represent unique one-dimensional organic semiconductors with chemical and physical properties that facilitate equivalent transport of electrons and holes. These factors have driven increasing attention to employing s-SWCNTs for electronic and energy harvesting applications, including thermoelectric (TE) generators. Here we demonstrate a combination of ink chemistry, solid-state polymer removal, and charge-transfer doping strategies that enable unprecedented n-type and p-type TE power factors, in the range of 700 μW m –1 Kmore » –2 at 298 K for the same solution-processed highly enriched thin films containing 100% s-SWCNTs. We also demonstrate that the thermal conductivity appears to decrease with decreasing s-SWCNT diameter, leading to a peak material zT ≈ 0.12 for s-SWCNTs with diameters in the range of 1.0 nm. Here, our results indicate that the TE performance of s-SWCNT-only material systems is approaching that of traditional inorganic semiconductors, paving the way for these materials to be used as the primary components for efficient, all-organic TE generators.« less

Probing in-plane anisotropy in fewlayer ReS₂ using low frequency noise measurement.

PubMed

Mitra, Richa; Jariwala, Bhakti; Bhattacharya, Arnab; Das, Anindya

2018-01-31

ReS₂, a layered two-dimensional material popular for its in-plane anisotropic properties is emerging as one of the potential candidates for flexible electronics and ultrafast optical applications. It is an n-type semiconducting material having a layer independent bandgap of 1.55 eV. In this paper we have characterized the intrinsic electronic noise level of fewlayer ReS₂ for the first time. Fewlayer ReS₂ FET devices show 1/f nature of noise for frequency ranging over three orders of magnitude. We have also observed that not only the electrical response of the material is anisotropic; the noise level is also direction dependent. In fact the noise is found to be more sensitive towards the anisotropy. This fact has been explained by evoking the theory where the Hooge parameter is not a constant quantity, but has a distinct power law dependence on mobility along the two axes direction. The anisotropy in 1/f noise measurement will pave the way to quantify the anisotropic nature of two-dimensional (2D) materials, which will be helpful for the design of low noise transistor in future. © 2018 IOP Publishing Ltd.

Bulk synthesis of inorganic fullerene-like MS{sub 2} (M = Mo, W) from the respective trioxides and the reaction mechanism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feldman, Y.; Frey, G.L.; Homyonfer, M.

Recently, milligram quantities of MoS{sub 2} fullerene-like nanotubes and negative curvature polyhedra (generically called inorganic fullerene-like material, IF), were reproducibly obtained by a phase reaction from an oxide precursor. The present work focuses on the mechanism of the synthesis of IF-MS{sub 2} (M = W, Mo). The IF material is obtained from oxide particles smaller than ca. 0.2 {mu}m, while larger oxide particles result in 2H-MS{sub 2} platelets. The key step in the reaction mechanism is the formation of a closed layer of MS{sub 2}, which isolates the nanoparticle from its surroundings and prevents its fusion into larger particles. Subsequently,more » the oxide core of the nanoparticle is progressively converted into a sulfide nanoparticle with an empty core (IF). Taking advantage of this process, we report here a routine for the fabrication of macroscopic quantities of a pure IF-WS{sub 2} phase with a very high yield. As anticipated, the size distribution of the IF material is determined by the size distribution of the oxide precursor. The present synthesis paves the way for a systematic study of these materials which are promising candidates for, e.g., solid lubrication. 32 refs., 5 figs., 2 tabs.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jiajun; Wang, Liguang; Eng, Christopher

We present that irreversible electrochemical behavior and large voltage hysteresis are commonly observed in battery materials, in particular for materials reacting through conversion reaction, resulting in undesirable round-trip energy loss and low coulombic efficiency. Seeking solutions to these challenges relies on the understanding of the underlying mechanism and physical origins. Here, this study combines in operando 2D transmission X-ray microscopy with X-ray absorption near edge structure, 3D tomography, and galvanostatic intermittent titration techniques to uncover the conversion reaction in sodium–metal sulfide batteries, a promising high-energy battery system. This study shows a high irreversible electrochemistry process predominately occurs at first cycle,more » which can be largely linked to Na ion trapping during the first desodiation process and large interfacial ion mobility resistance. Subsequently, phase transformation evolution and electrochemical reaction show good reversibility at multiple discharge/charge cycles due to materials' microstructural change and equilibrium. The origin of large hysteresis between discharge and charge is investigated and it can be attributed to multiple factors including ion mobility resistance at the two-phase interface, intrinsic slow sodium ion diffusion kinetics, and irreversibility as well as ohmic voltage drop and overpotential. In conclusion, this study expects that such understandings will help pave the way for engineering design and optimization of materials microstructure for future-generation batteries.« less

Ultrafast magnon generation in an Fe film on Cu(100).

PubMed

Schmidt, A B; Pickel, M; Donath, M; Buczek, P; Ernst, A; Zhukov, V P; Echenique, P M; Sandratskii, L M; Chulkov, E V; Weinelt, M

2010-11-05

We report on a combined experimental and theoretical study of the spin-dependent relaxation processes in the electron system of an iron film on Cu(100). Spin-, time-, energy- and angle-resolved two-photon photoemission shows a strong characteristic dependence of the lifetime of photoexcited electrons on their spin and energy. Ab initio calculations as well as a many-body treatment corroborate that the observed properties are determined by relaxation processes involving magnon emission. Thereby we demonstrate that magnon emission by hot electrons occurs on the femtosecond time scale and thus provides a significant source of ultrafast spin-flip processes. Furthermore, engineering of the magnon spectrum paves the way for tuning the dynamic properties of magnetic materials.

Geometric charges in theories of elasticity and plasticity

NASA Astrophysics Data System (ADS)

Moshe, Michael

The mechanics of many natural systems is governed by localized sources of stresses. Examples include ''plastic events'' that occur in amorphous solids under external stress, defects formation in crystalline material, and force-dipoles applied by cells adhered to an elastic substrate. Recent developments in a geometric formulation of elasticity theory paved the way for a unifying mathematical description of such singular sources of stress, as ''elastic charges''. In this talk I will review basic results in this emerging field, focusing on the geometry and mechanics of elastic charges in two-dimensional solid bodies. I will demonstrate the applicability of this new approach in three different problems: failure of an amorphous solid under load, mechanics of Kirigami, and wrinkle patterns in geometrically-incompatible elastic sheets.

Observation of the Quantum Hall Effect in Confined Films of the Three-Dimensional Dirac Semimetal Cd3 As2

NASA Astrophysics Data System (ADS)

Schumann, Timo; Galletti, Luca; Kealhofer, David A.; Kim, Honggyu; Goyal, Manik; Stemmer, Susanne

2018-01-01

The magnetotransport properties of epitaxial films of Cd3 As2 , a paradigm three-dimensional Dirac semimetal, are investigated. We show that an energy gap opens in the bulk electronic states of sufficiently thin films and, at low temperatures, carriers residing in surface states dominate the electrical transport. The carriers in these states are sufficiently mobile to give rise to a quantized Hall effect. The sharp quantization demonstrates surface transport that is virtually free of parasitic bulk conduction and paves the way for novel quantum transport studies in this class of topological materials. Our results also demonstrate that heterostructuring approaches can be used to study and engineer quantum states in topological semimetals.

Brownian motion of graphene.

PubMed

Maragó, Onofrio M; Bonaccorso, Francesco; Saija, Rosalba; Privitera, Giulia; Gucciardi, Pietro G; Iatì, Maria Antonia; Calogero, Giuseppe; Jones, Philip H; Borghese, Ferdinando; Denti, Paolo; Nicolosi, Valeria; Ferrari, Andrea C

2010-12-28

Brownian motion is a manifestation of the fluctuation-dissipation theorem of statistical mechanics. It regulates systems in physics, biology, chemistry, and finance. We use graphene as prototype material to unravel the consequences of the fluctuation-dissipation theorem in two dimensions, by studying the Brownian motion of optically trapped graphene flakes. These orient orthogonal to the light polarization, due to the optical constants anisotropy. We explain the flake dynamics in the optical trap and measure force and torque constants from the correlation functions of the tracking signals, as well as comparing experiments with a full electromagnetic theory of optical trapping. The understanding of optical trapping of two-dimensional nanostructures gained through our Brownian motion analysis paves the way to light-controlled manipulation and all-optical sorting of biological membranes and anisotropic macromolecules.

Unconventional Superconductivity in La(7)Ir(3) Revealed by Muon Spin Relaxation: Introducing a New Family of Noncentrosymmetric Superconductor That Breaks Time-Reversal Symmetry.

PubMed

Barker, J A T; Singh, D; Thamizhavel, A; Hillier, A D; Lees, M R; Balakrishnan, G; Paul, D McK; Singh, R P

2015-12-31

The superconductivity of the noncentrosymmetric compound La(7)Ir(3) is investigated using muon spin rotation and relaxation. Zero-field measurements reveal the presence of spontaneous static or quasistatic magnetic fields below the superconducting transition temperature T(c)=2.25  K-a clear indication that the superconducting state breaks time-reversal symmetry. Furthermore, transverse-field rotation measurements suggest that the superconducting gap is isotropic and that the pairing symmetry of the superconducting electrons is predominantly s wave with an enhanced binding strength. The results indicate that the superconductivity in La(7)Ir(3) may be unconventional and paves the way for further studies of this family of materials.

Selective Modification of Chitin and Chitosan: En Route to Tailored Oligosaccharides.

PubMed

Carvalho, Luísa C R; Queda, Fausto; Santos, Cátia V Almeida; Marques, M Manuel B

2016-12-19

Chitin and chitosan are attractive biopolymers with enormous structural possibilities for chemical modification, creating platforms for new chemical entities with a broad scope of applications, ranging from material science to medicine. During the last few years, incredible efforts have been dedicated to the regioselective modification of these biopolymers paving the way for improved properties and tailored activities. Herein, the most recent advances in chitin/chitosan regioselective modification, reaction conditions, selectivity, and the impact on its applications are highlighted. Moreover, the recent focus on chitooligosaccharides, their regioselective and chemoselective functionalization, as well as their role in biological studies, including molecular recognition with several biological targets are also covered. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spontaneous generation of frequency combs in QD lasers

NASA Astrophysics Data System (ADS)

Columbo, Lorenzo Luigi; Bardella, Paolo; Gioannini, Mariangela

2018-02-01

We report a systematic analysis of the phenomenon of self-generation of optical frequency combs in single section Fabry-Perot Quantum Dot lasers using a Time Domain Travelling Wave model. We show that the carriers grating due to the standing wave pattern (spatial hole burning) peculiar of Quantum Dots laser and the Four Wave Mixing are the key ingredients to explain spontaneous Optical Frequency Combs in these devices. Our results well agree with recent experimental evidences reported in semiconductor lasers based on Quantum Dots and Quantum Dashes active material and pave the way to the development of a simulation tool for the design of these comb laser sources for innovative applications in the field of high-data rate optical communications.

Noninvasive micromanipulation of live HIV-1 infected cells via laser light

NASA Astrophysics Data System (ADS)

Mthunzi, Patience

2015-12-01

Live mammalian cells from various tissues of origin can be aseptically and noninvasively micromanipulated via lasers of different regimes. Laser-driven techniques are therefore paving a path toward the advancement of human immuno-deficiency virus (HIV-1) investigations. Studies aimed at the interaction of laser light, nanomaterials, and biological materials can also lead to an understanding of a wealth of disease conditions and result in photonics-based therapies and diagnostic tools. Thus, in our research, both continuous wave and pulsed lasers operated at varying wavelengths are employed, as they possess special properties that allow classical biomedical applications. This paper discusses photo-translocation of antiretroviral drugs into HIV-1 permissive cells and preliminary results of low-level laser therapy (LLLT) in HIV-1 infected cells.

Exploiting short-term memory in soft body dynamics as a computational resource

PubMed Central

Nakajima, K.; Li, T.; Hauser, H.; Pfeifer, R.

2014-01-01

Soft materials are not only highly deformable, but they also possess rich and diverse body dynamics. Soft body dynamics exhibit a variety of properties, including nonlinearity, elasticity and potentially infinitely many degrees of freedom. Here, we demonstrate that such soft body dynamics can be employed to conduct certain types of computation. Using body dynamics generated from a soft silicone arm, we show that they can be exploited to emulate functions that require memory and to embed robust closed-loop control into the arm. Our results suggest that soft body dynamics have a short-term memory and can serve as a computational resource. This finding paves the way towards exploiting passive body dynamics for control of a large class of underactuated systems. PMID:25185579

Dynamic transition in the structure of an energetic crystal during chemical reactions at shock front prior to detonation.

PubMed

Nomura, Ken-Ichi; Kalia, Rajiv K; Nakano, Aiichiro; Vashishta, Priya; van Duin, Adri C T; Goddard, William A

2007-10-05

Mechanical stimuli in energetic materials initiate chemical reactions at shock fronts prior to detonation. Shock sensitivity measurements provide widely varying results, and quantum-mechanical calculations are unable to handle systems large enough to describe shock structure. Recent developments in reactive force-field molecular dynamics (ReaxFF-MD) combined with advances in parallel computing have paved the way to accurately simulate reaction pathways along with the structure of shock fronts. Our multimillion-atom ReaxFF-MD simulations of l,3,5-trinitro-l,3,5-triazine (RDX) reveal that detonation is preceded by a transition from a diffuse shock front with well-ordered molecular dipoles behind it to a disordered dipole distribution behind a sharp front.

Paper-based chemiresistor for detection of ultralow concentrations of protein.

PubMed

Pozuelo, Marta; Blondeau, Pascal; Novell, Marta; Andrade, Francisco J; Xavier Rius, F; Riu, Jordi

2013-11-15

A new paper-based chemiresistor composed of a network of single-wall carbon nanotubes (SWCNTs) and anti-human immunoglobulin G (anti-HIgG) is reported herein. SWCNTs act as outstanding transducers because they provide high sensitivity in terms of resistance changes due to immunoreaction. As a result, the resistance-based biosensor reaches concentration detection as low as picomolar. The resulting paper-based biosensor is sensitive, selective and employs low-cost substrate and simple manufacturing stages. Since chemiresistors require low-power equipment and are able to detect low concentrations with inexpensive materials, the present approach may pave the way for the development of resistive biosensors at very low-cost with high performances. Copyright © 2013 Elsevier B.V. All rights reserved.

Self-organized pattern formation at organic-inorganic interfaces during deposition: Experiment versus modeling

NASA Astrophysics Data System (ADS)

Szillat, F.; Mayr, S. G.

2011-09-01

Self-organized pattern formation during physical vapor deposition of organic materials onto rough inorganic substrates is characterized by a complex morphological evolution as a function of film thickness. We employ a combined experimental-theoretical study using atomic force microscopy and numerically solved continuum rate equations to address morphological evolution in the model system: poly(bisphenol A carbonate) on polycrystalline Cu. As the key ingredients for pattern formation, (i) curvature and interface potential driven surface diffusion, (ii) deposition noise, and (iii) interface boundary effects are identified. Good agreement of experiments and theory, fitting only the Hamaker constant and diffusivity within narrow physical parameter windows, corroborates the underlying physics and paves the way for computer-assisted interface engineering.

Spatial and temporal control of the diazonium modification of sp2 carbon surfaces.

PubMed

Kirkman, Paul M; Güell, Aleix G; Cuharuc, Anatolii S; Unwin, Patrick R

2014-01-08

Interest in the controlled chemical functionalization of sp(2) carbon materials using diazonium compounds has been recently reignited, particularly as a means to generate a band gap in graphene. We demonstrate local diazonium modification of pristine sp(2) carbon surfaces, with high control, at the micrometer scale through the use of scanning electrochemical cell microscopy (SECCM). Electrochemically driven diazonium patterning is investigated at a range of driving forces, coupled with surface analysis using atomic force microscopy (AFM) and Raman spectroscopy. We highlight how the film density, level of sp(2)/sp(3) rehybridization and the extent of multilayer formation can be controlled, paving the way for the use of localized electrochemistry as a route to controlled diazonium modification.

Mapping the layer count of few-layer hexagonal boron nitride at high lateral spatial resolutions

NASA Astrophysics Data System (ADS)

Mohsin, Ali; Cross, Nicholas G.; Liu, Lei; Watanabe, Kenji; Taniguchi, Takashi; Duscher, Gerd; Gu, Gong

2018-01-01

Layer count control and uniformity of two dimensional (2D) layered materials are critical to the investigation of their properties and to their electronic device applications, but methods to map 2D material layer count at nanometer-level lateral spatial resolutions have been lacking. Here, we demonstrate a method based on two complementary techniques widely available in transmission electron microscopes (TEMs) to map the layer count of multilayer hexagonal boron nitride (h-BN) films. The mass-thickness contrast in high-angle annular dark-field (HAADF) imaging in the scanning transmission electron microscope (STEM) mode allows for thickness determination in atomically clean regions with high spatial resolution (sub-nanometer), but is limited by surface contamination. To complement, another technique based on the boron K ionization edge in the electron energy loss spectroscopy spectrum (EELS) of h-BN is developed to quantify the layer count so that surface contamination does not cause an overestimate, albeit at a lower spatial resolution (nanometers). The two techniques agree remarkably well in atomically clean regions with discrepancies within  ±1 layer. For the first time, the layer count uniformity on the scale of nanometers is quantified for a 2D material. The methodology is applicable to layer count mapping of other 2D layered materials, paving the way toward the synthesis of multilayer 2D materials with homogeneous layer count.

Photocatalytic water splitting—The untamed dream: A review of recent advances

DOE PAGES

Jafari, Tahereh; Moharreri, Ehsan; Amin, Alireza Shirazi; ...

2016-07-09

Here, photocatalytic water splitting using sunlight is a promising technology capable of providing high energy yield without pollutant byproducts. Herein, we review various aspects of this technology including chemical reactions, physiochemical conditions and photocatalyst types such as metal oxides, sulfides, nitrides, nanocomposites, and doped materials followed by recent advances in computational modeling of photoactive materials. As the best-known catalyst for photocatalytic hydrogen and oxygen evolution, TiO 2 is discussed in a separate section, along with its challenges such as the wide band gap, large overpotential for hydrogen evolution, and rapid recombination of produced electron-hole pairs. Various approaches are addressed tomore » overcome these shortcomings, such as doping with different elements, heterojunction catalysts, noble metal deposition, and surface modification. Development of a photocatalytic corrosion resistant, visible light absorbing, defect-tuned material with small particle size is the key to complete the sunlight to hydrogen cycle efficiently. Computational studies have opened new avenues to understand and predict the electronic density of states and band structure of advanced materials and could pave the way for the rational design of efficient photocatalysts for water splitting. Future directions are focused on developing innovative junction architectures, novel synthesis methods and optimizing the existing active materials to enhance charge transfer, visible light absorption, reducing the gas evolution overpotential and maintaining chemical and physical stability« less

A Polycarboxyl-Decorated FeIII -Based Xerogel-Derived Multifunctional Composite (Fe3 O4 /Fe/C) as an Efficient Electrode Material towards Oxygen Reduction Reaction and Supercapacitor Application.

PubMed

Devi, Bandhana; Venkateswarulu, Mangili; Kushwaha, Himmat Singh; Halder, Aditi; Koner, Rik Rani

2018-05-02

Low cost, non-noble metal catalysts with a good oxygen reduction reaction (ORR) activity comparable to that of platinum and also having good energy storage properties are highly desirable but challenging. Several challenges are associated with the development of such materials. Herein, we demonstrate a new polycarboxyl-functionalised Fe III -based gel material, synthesised following a solvothermal method and the development of its composite (Fe 3 O 4 /Fe/C) by annealing at optimised temperature. The developed composite displayed excellent electrocatalytic activity for the oxygen reduction reaction with an onset potential of 0.87 V (vs. RHE) and a current density value of -5 mA cm -2 , which are comparable with commercial 20 wt % Pt/C. In addition, as one of the most desirable properties, the composite exhibits a better methanol tolerance and greater durability than Pt/C. The same material was explored as an energy storage material for supercapacitors, which showed a specific capacitance of 245 F g -1 at a current density of 1 A g -1 . It is expected that this Fe 3 O 4 /Fe/C composite with a disordered graphitised carbon matrix will pave a horizon for developing energy conversion and energy storage devices. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

New routes to the functionalization patterning and manufacture of graphene-based materials for biomedical applications.

PubMed

De Sanctis, A; Russo, S; Craciun, M F; Alexeev, A; Barnes, M D; Nagareddy, V K; Wright, C D

2018-06-06

Graphene-based materials are being widely explored for a range of biomedical applications, from targeted drug delivery to biosensing, bioimaging and use for antibacterial treatments, to name but a few. In many such applications, it is not graphene itself that is used as the active agent, but one of its chemically functionalized forms. The type of chemical species used for functionalization will play a key role in determining the utility of any graphene-based device in any particular biomedical application, because this determines to a large part its physical, chemical, electrical and optical interactions. However, other factors will also be important in determining the eventual uptake of graphene-based biomedical technologies, in particular the ease and cost of manufacture of proposed device and system designs. In this work, we describe three novel routes for the chemical functionalization of graphene using oxygen, iron chloride and fluorine. We also introduce novel in situ methods for controlling and patterning such functionalization on the micro- and nanoscales. Our approaches are readily transferable to large-scale manufacturing, potentially paving the way for the eventual cost-effective production of functionalized graphene-based materials, devices and systems for a range of important biomedical applications.

Three-Dimensional Nanoprinting via Direct Delivery.

PubMed

Ventrici de Souza, Joao; Liu, Yang; Wang, Shuo; Dörig, Pablo; Kuhl, Tonya L; Frommer, Jane; Liu, Gang-Yu

2018-01-18

Direct writing methods are a generic and simple means to produce designed structures in three dimensions (3D). The printing is achieved by extruding printing materials through a nozzle, which provides a platform to deliver a wide range of materials. Although this method has been routinely used for 3D printing at macroscopic scales, miniaturization to micrometer and nanometer scales and building hierarchical structures at multidimensional scales represent new challenges in research and development. The current work addresses these challenges by combining the spatial precision of atomic force microscopy (AFM) and local delivery capability of microfluidics. Specialized AFM probes serve dual roles of a microscopy tip and a delivery tool, enabling the miniaturization of 3D printing via direct material delivery. Stacking grids of 20 μm periodicity were printed layer-by-layer covering 1 mm × 1 mm regions. The spatial fidelity was measured to be several nanometers, which is among the highest in 3D printing. The results clearly demonstrate the feasibility of achieving high precision 3D nanoprinting with nanometer feature size and accuracy with practical throughput and overall size. This work paves the way for advanced applications of 3D hierarchical nanostructures.

Exploiting negative Poisson's ratio to design 3D-printed composites with enhanced mechanical properties

DOE PAGES

Li, Tiantian; Chen, Yanyu; Hu, Xiaoyi; ...

2018-02-03

Auxetic materials exhibiting a negative Poisson's ratio are shown to have better indentation resistance, impact shielding capability, and enhanced toughness. Here, we report a class of high-performance composites in which auxetic lattice structures are used as the reinforcements and the nearly incompressible soft material is employed as the matrix. This coupled geometry and material design concept is enabled by the state-of-the-art additive manufacturing technique. Guided by experimental tests and finite element analyses, we systematically study the compressive behavior of the 3D printed auxetics reinforced composites and achieve a significant enhancement of their stiffness and energy absorption. This improved mechanical performancemore » is due to the negative Poisson's ratio effect of the auxetic reinforcements, which makes the matrix in a state of biaxial compression and hence provides additional support. This mechanism is further supported by the investigation of the effect of auxetic degree on the stiffness and energy absorption capability. The findings reported here pave the way for developing a new class of auxetic composites that significantly expand their design space and possible applications through a combination of rational design and 3D printing.« less

Exploiting negative Poisson's ratio to design 3D-printed composites with enhanced mechanical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Tiantian; Chen, Yanyu; Hu, Xiaoyi

Auxetic materials exhibiting a negative Poisson's ratio are shown to have better indentation resistance, impact shielding capability, and enhanced toughness. Here, we report a class of high-performance composites in which auxetic lattice structures are used as the reinforcements and the nearly incompressible soft material is employed as the matrix. This coupled geometry and material design concept is enabled by the state-of-the-art additive manufacturing technique. Guided by experimental tests and finite element analyses, we systematically study the compressive behavior of the 3D printed auxetics reinforced composites and achieve a significant enhancement of their stiffness and energy absorption. This improved mechanical performancemore » is due to the negative Poisson's ratio effect of the auxetic reinforcements, which makes the matrix in a state of biaxial compression and hence provides additional support. This mechanism is further supported by the investigation of the effect of auxetic degree on the stiffness and energy absorption capability. The findings reported here pave the way for developing a new class of auxetic composites that significantly expand their design space and possible applications through a combination of rational design and 3D printing.« less

Van der Waals epitaxy and photoresponse of hexagonal tellurium nanoplates on flexible mica sheets.

PubMed

Wang, Qisheng; Safdar, Muhammad; Xu, Kai; Mirza, Misbah; Wang, Zhenxing; He, Jun

2014-07-22

Van der Waals epitaxy (vdWE) is of great interest due to its extensive applications in the synthesis of ultrathin two-dimensional (2D) layered materials. However, vdWE of nonlayered functional materials is still not very well documented. Here, although tellurium has a strong tendency to grow into one-dimensional nanoarchitecture due to its chain-like structure, we successfully realize 2D hexagonal tellurium nanoplates on flexible mica sheets via vdWE. Chemically inert mica surface is found to be crucial for the lateral growth of hexagonal tellurium nanoplates since it (1) facilitates the migration of tellurium adatoms along mica surface and (2) allows a large lattice mismatch. Furthermore, 2D tellurium hexagonal nanoplates-based photodetectors are in situ fabricated on flexible mica sheets. Efficient photoresponse is obtained even after bending the device for 100 times, indicating 2D tellurium hexagonal nanoplates-based photodetectors on mica sheets have a great application potential in flexible and wearable optoelectronic devices. We believe the fundamental understanding of vdWE effect on the growth of 2D tellurium hexagonal nanoplate can pave the way toward leveraging vdWE as a useful channel to realize the 2D geometry of other nonlayered materials.

Hyperspectral Sensor Data Capability for Retrieving Complex Urban Land Cover in Comparison with Multispectral Data: Venice City Case Study (Italy)

PubMed Central

Cavalli, Rosa Maria; Fusilli, Lorenzo; Pascucci, Simone; Pignatti, Stefano; Santini, Federico

2008-01-01

This study aims at comparing the capability of different sensors to detect land cover materials within an historical urban center. The main objective is to evaluate the added value of hyperspectral sensors in mapping a complex urban context. In this study we used: (a) the ALI and Hyperion satellite data, (b) the LANDSAT ETM+ satellite data, (c) MIVIS airborne data and (d) the high spatial resolution IKONOS imagery as reference. The Venice city center shows a complex urban land cover and therefore was chosen for testing the spectral and spatial characteristics of different sensors in mapping the urban tissue. For this purpose, an object-oriented approach and different common classification methods were used. Moreover, spectra of the main anthropogenic surfaces (i.e. roofing and paving materials) were collected during the field campaigns conducted on the study area. They were exploited for applying band-depth and sub-pixel analyses to subsets of Hyperion and MIVIS hyperspectral imagery. The results show that satellite data with a 30m spatial resolution (ALI, LANDSAT ETM+ and HYPERION) are able to identify only the main urban land cover materials. PMID:27879879

Highly Porous Thermoelectric Nanocomposites with Low Thermal Conductivity and High Figure of Merit from Large-Scale Solution-Synthesized Bi2 Te2.5 Se0.5 Hollow Nanostructures.

PubMed

Xu, Biao; Feng, Tianli; Agne, Matthias T; Zhou, Lin; Ruan, Xiulin; Snyder, G Jeffery; Wu, Yue

2017-03-20

To enhance the performance of thermoelectric materials and enable access to their widespread applications, it is beneficial yet challenging to synthesize hollow nanostructures in large quantities, with high porosity, low thermal conductivity (κ) and excellent figure of merit (z T). Herein we report a scalable (ca. 11.0 g per batch) and low-temperature colloidal processing route for Bi 2 Te 2.5 Se 0.5 hollow nanostructures. They are sintered into porous, bulk nanocomposites (phi 10 mm×h 10 mm) with low κ (0.48 W m -1  K -1 ) and the highest z T (1.18) among state-of-the-art Bi 2 Te 3-x Se x materilas. Additional benefits of the unprecedented low relative density (68-77 %) are the large demand reduction of raw materials and the improved portability. This method can be adopted to fabricate other porous phase-transition and thermoelectric chalcogenide materials and will pave the way for the implementation of hollow nanostructures in other fields. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reliably Modeling the Mechanical Stability of Rigid and Flexible Metal–Organic Frameworks

PubMed Central

2017-01-01

Conspectus Over the past two decades, metal–organic frameworks (MOFs) have matured from interesting academic peculiarities toward a continuously expanding class of hybrid, nanoporous materials tuned for targeted technological applications such as gas storage and heterogeneous catalysis. These oft-times crystalline materials, composed of inorganic moieties interconnected by organic ligands, can be endowed with desired structural and chemical features by judiciously functionalizing or substituting these building blocks. As a result of this reticular synthesis, MOF research is situated at the intriguing intersection between chemistry and physics, and the building block approach could pave the way toward the construction of an almost infinite number of possible crystalline structures, provided that they exhibit stability under the desired operational conditions. However, this enormous potential is largely untapped to date, as MOFs have not yet found a major breakthrough in technological applications. One of the remaining challenges for this scale-up is the densification of MOF powders, which is generally achieved by subjecting the material to a pressurization step. However, application of an external pressure may substantially alter the chemical and physical properties of the material. A reliable theoretical guidance that can presynthetically identify the most stable materials could help overcome this technological challenge. In this Account, we describe the recent research the progress on computational characterization of the mechanical stability of MOFs. So far, three complementary approaches have been proposed, focusing on different aspects of mechanical stability: (i) the Born stability criteria, (ii) the anisotropy in mechanical moduli such as the Young and shear moduli, and (iii) the pressure-versus-volume equations of state. As these three methods are grounded in distinct computational approaches, it is expected that their accuracy and efficiency will vary. To date, however, it is unclear which set of properties are suited and reliable for a given application, as a comprehensive comparison for a broad variety of MOFs is absent, impeding the widespread use of these theoretical frameworks. Herein, we fill this gap by critically assessing the performance of the three computational models on a broad set of MOFs that are representative for current applications. These materials encompass the mechanically rigid UiO-66(Zr) and MOF-5(Zn) as well as the flexible MIL-47(V) and MIL-53(Al), which undergo pressure-induced phase transitions. It is observed that the Born stability criteria and pressure-versus-volume equations of state give complementary insight into the macroscopic and microscopic origins of instability, respectively. However, interpretation of the Born stability criteria becomes increasingly difficult when less symmetric materials are considered. Moreover, pressure fluctuations during the simulations hamper their accuracy for flexible materials. In contrast, the pressure-versus-volume equations of state are determined in a thermodynamic ensemble specifically targeted to mitigate the effects of these instantaneous fluctuations, yielding more accurate results. The critical Account presented here paves the way toward a solid computational framework for an extensive presynthetic screening of MOFs to select those that are mechanically stable and can be postsynthetically densified before their use in targeted applications. PMID:29155552

Reliably Modeling the Mechanical Stability of Rigid and Flexible Metal-Organic Frameworks.

PubMed

Rogge, Sven M J; Waroquier, Michel; Van Speybroeck, Veronique

2018-01-16

Over the past two decades, metal-organic frameworks (MOFs) have matured from interesting academic peculiarities toward a continuously expanding class of hybrid, nanoporous materials tuned for targeted technological applications such as gas storage and heterogeneous catalysis. These oft-times crystalline materials, composed of inorganic moieties interconnected by organic ligands, can be endowed with desired structural and chemical features by judiciously functionalizing or substituting these building blocks. As a result of this reticular synthesis, MOF research is situated at the intriguing intersection between chemistry and physics, and the building block approach could pave the way toward the construction of an almost infinite number of possible crystalline structures, provided that they exhibit stability under the desired operational conditions. However, this enormous potential is largely untapped to date, as MOFs have not yet found a major breakthrough in technological applications. One of the remaining challenges for this scale-up is the densification of MOF powders, which is generally achieved by subjecting the material to a pressurization step. However, application of an external pressure may substantially alter the chemical and physical properties of the material. A reliable theoretical guidance that can presynthetically identify the most stable materials could help overcome this technological challenge. In this Account, we describe the recent research the progress on computational characterization of the mechanical stability of MOFs. So far, three complementary approaches have been proposed, focusing on different aspects of mechanical stability: (i) the Born stability criteria, (ii) the anisotropy in mechanical moduli such as the Young and shear moduli, and (iii) the pressure-versus-volume equations of state. As these three methods are grounded in distinct computational approaches, it is expected that their accuracy and efficiency will vary. To date, however, it is unclear which set of properties are suited and reliable for a given application, as a comprehensive comparison for a broad variety of MOFs is absent, impeding the widespread use of these theoretical frameworks. Herein, we fill this gap by critically assessing the performance of the three computational models on a broad set of MOFs that are representative for current applications. These materials encompass the mechanically rigid UiO-66(Zr) and MOF-5(Zn) as well as the flexible MIL-47(V) and MIL-53(Al), which undergo pressure-induced phase transitions. It is observed that the Born stability criteria and pressure-versus-volume equations of state give complementary insight into the macroscopic and microscopic origins of instability, respectively. However, interpretation of the Born stability criteria becomes increasingly difficult when less symmetric materials are considered. Moreover, pressure fluctuations during the simulations hamper their accuracy for flexible materials. In contrast, the pressure-versus-volume equations of state are determined in a thermodynamic ensemble specifically targeted to mitigate the effects of these instantaneous fluctuations, yielding more accurate results. The critical Account presented here paves the way toward a solid computational framework for an extensive presynthetic screening of MOFs to select those that are mechanically stable and can be postsynthetically densified before their use in targeted applications.

High Throughput Discovery of Solar Fuels Photoanodes in the CuO-V 2 O 5 System

DOE PAGES

Zhou, Lan; Yan, Qimin; Shinde, Aniketa; ...

2015-08-26

Solar photoelectrochemical generation of fuel is a promising energy technology yet the lack of an efficient, robust photoanode remains a primary materials challenge in the development and deployment of solar fuels generators. Metal oxides comprise the most promising class of photoanode materials, but no known material meets the demanding requirements of low band gap energy, photoelectrocatalysis of the oxygen evolution reaction, and stability under highly oxidizing conditions. Here, we report the identification of new photoelectroactive materials through a strategic combination of combinatorial materials synthesis, high-throughput photoelectrochemistry, optical spectroscopy, and detailed electronic structure calculations. We identify 4 photoelectrocatalyst phases - α-Cumore » 2V 2O 7, β-Cu 2V 2O 7, γ-Cu 3V 2O 8, and Cu 11V 6O 26 - with band gap energy at or below 2 eV. The photoelectrochemical properties and 30-minute stability of these copper vanadate phases are demonstrated in 3 different aqueous electrolytes (pH 7, pH 9, and pH 13), with select combinations of phase and electrolyte exhibiting unprecedented photoelectrocatalytic stability for metal oxides with sub-2 eV band gap. Through integration of experimental and theoretical techniques, we determine new structure-property relationships and establish CuO-V 2O 5 as the most prominent composition system for OER photoelectrocatalysts, providing crucial information for materials genomes initiatives and paving the way for continued development of solar fuels photoanodes.« less

Theoretical Investigations of Well-Defined Graphene Nanostructures: Catalysis, Spectroscopy, and Development of Novel Fragment-Based Models

NASA Astrophysics Data System (ADS)

Noffke, Benjamin W.

Carbon materials have the potential to replace some precious metals in renewable energy applications. These materials are particularly attractive because of the elemental abundance and relatively low nuclear mass of carbon, implying economically feasible and lightweight materials. Targeted design of carbon materials is hindered by the lack of fundamental understanding that is required to tailor their properties for the desired application. However, most available synthetic methods to create carbon materials involve harsh conditions that limit the control of the resulting structure. Without a well-defined structure, the system is too complex and fundamental studies cannot be definitive. This work seeks to gain fundamental understanding through the development and application of efficient computational models for these systems, in conjunction with experiments performed on soluble, well-defined graphene nanostructures prepared by our group using a bottom-up synthetic approach. Theory is used to determine mechanistic details for well-defined carbon systems in applications of catalysis and electrochemical transformations. The resulting computational models do well to explain previous observations of carbon materials and provide suggestions for future directions. However, as the system size of the nanostructures gets larger, the computational cost can become prohibitive. To reduce the computational scaling of quantum chemical calculations, a new fragmentation scheme has been developed that addresses the challenges of fragmenting conjugated molecules. By selecting fragments that retain important structural characteristics in graphene, a more efficient method is achieved. The new method paves the way for an automated, systematic fragmentation scheme of graphene molecules.

Active material, optical mode and cavity impact on nanoscale electro-optic modulation performance

NASA Astrophysics Data System (ADS)

Amin, Rubab; Suer, Can; Ma, Zhizhen; Sarpkaya, Ibrahim; Khurgin, Jacob B.; Agarwal, Ritesh; Sorger, Volker J.

2017-10-01

Electro-optic modulation is a key function in optical data communication and possible future optical compute engines. The performance of modulators intricately depends on the interaction between the actively modulated material and the propagating waveguide mode. While a variety of high-performance modulators have been demonstrated, no comprehensive picture of what factors are most responsible for high performance has emerged so far. Here we report the first systematic and comprehensive analytical and computational investigation for high-performance compact on-chip electro-optic modulators by considering emerging active materials, model considerations and cavity feedback at the nanoscale. We discover that the delicate interplay between the material characteristics and the optical mode properties plays a key role in defining the modulator performance. Based on physical tradeoffs between index modulation, loss, optical confinement factors and slow-light effects, we find that there exist combinations of bias, material and optical mode that yield efficient phase or amplitude modulation with acceptable insertion loss. Furthermore, we show how material properties in the epsilon near zero regime enable reduction of length by as much as by 15 times. Lastly, we introduce and apply a cavity-based electro-optic modulator figure of merit, Δλ/Δα, relating obtainable resonance tuning via phase shifting relative to the incurred losses due to the fundamental Kramers-Kronig relations suggesting optimized device operating regions with optimized modulation-to-loss tradeoffs. This work paves the way for a holistic design rule of electro-optic modulators for high-density on-chip integration.

Lattice strain in irradiated materials unveils a prevalent defect evolution mechanism

NASA Astrophysics Data System (ADS)

Debelle, Aurélien; Crocombette, Jean-Paul; Boulle, Alexandre; Chartier, Alain; Jourdan, Thomas; Pellegrino, Stéphanie; Bachiller-Perea, Diana; Carpentier, Denise; Channagiri, Jayanth; Nguyen, Tien-Hien; Garrido, Frédérico; Thomé, Lionel

2018-01-01

Modification of materials using ion beams has become a widespread route to improve or design materials for advanced applications, from ion doping for microelectronic devices to emulation of nuclear reactor environments. Yet, despite decades of studies, major issues regarding ion/solid interactions are not solved, one of them being the lattice-strain development process in irradiated crystals. In this work, we address this question using a consistent approach that combines x-ray diffraction (XRD) measurements with both molecular dynamics (MD) and rate equation cluster dynamics (RECD) simulations. We investigate four distinct materials that differ notably in terms of crystalline structure and nature of the atomic bonding. We demonstrate that these materials exhibit a common behavior with respect to the strain development process. In fact, a strain build-up followed by a strain relaxation is observed in the four investigated cases. The strain variation is unambiguously ascribed to a change in the defect configuration, as revealed by MD simulations. Strain development is due to the clustering of interstitial defects into dislocation loops, while the strain release is associated with the disappearance of these loops through their integration into a network of dislocation lines. RECD calculations of strain depth profiles, which are in agreement with experimental data, indicate that the driving force for the change in the defect nature is the defect clustering process. This study paves the way for quantitative predictions of the microstructure changes in irradiated materials.

PM10 and PM2.5 chemical source profiles with optical attenuation and health risk indicators of paved and unpaved road dust in Bhopal, India.

PubMed

Samiksha, Shilpi; Sunder Raman, Ramya; Nirmalkar, Jayant; Kumar, Samresh; Sirvaiya, Rohit

2017-03-01

Size classified (PM 10 and PM 2.5 ) paved and unpaved road dust chemical source profiles, optical attenuation and potential health risk from exposure to these sources are reported in this study. A total of 45 samples from 9 paved road and 6 unpaved road sites located in and around Bhopal were re-suspended in the laboratory, collected onto filter substrates and subjected to a variety of chemical analyses. In general, road dust was enriched (compared to upper continental crustal abundance) in anthropogenic pollutants including Sb, Cu, Zn, Co, and Pb. Organic and elemental carbon (OC/EC) in PM 10 and PM 2.5 size fractions were 50-75% higher in paved road dust compared to their counterparts in unpaved road dust. Further, the results suggest that when it is not possible to include carbon fractions in source profiles, the inclusion of optical attenuation is likely to enhance the source resolution of receptor models. Additionally, profiles obtained in this study were not very similar to the US EPA SPECIATE composite profiles for PM 10 and PM 2.5 , for both sources. Specifically, the mass fractions of Si, Fe, OC, and EC were most different between SPECIATE composite profiles and Bhopal composite profiles. An estimate of health indicators for Bhopal road dust revealed that although Cr was only marginally enriched, its inhalation may pose a health risk. The estimates of potential lifetime incremental cancer risk induced by the inhalation of Cr in paved and unpaved road dust (PM 10 and PM 2.5 ) for both adults and children were higher than the baseline values of acceptable risk. These results suggest that road dust Cr induced carcinogenic risk should be further investigated. Copyright © 2016 Elsevier Ltd. All rights reserved.

Permeability of roads to movement of scrubland lizards and small mammals

USGS Publications Warehouse

Brehme, Cheryl S.; Tracey, Jeff A.; McClenaghan, Leroy R.; Fisher, Robert N.

2013-01-01

A primary objective of road ecology is to understand and predict how roads affect connectivity of wildlife populations. Road avoidance behavior can fragment populations, whereas lack of road avoidance can result in high mortality due to wildlife-vehicle collisions. Many small animal species focus their activities to particular microhabitats within their larger habitat. We sought to assess how different types of roads affect the movement of small vertebrates and to explore whether responses to roads may be predictable on the basis of animal life history or microhabitat preferences preferences. We tracked the movements of fluorescently marked animals at 24 sites distributed among 3 road types: low-use dirt, low-use secondary paved, and rural 2-lane highway. Most data we collected were on the San Diego pocket mouse (Chaetodipus fallax), cactus mouse (Peromyscus eremicus), western fence lizard (Sceloporus occidentalis), orange-throated whiptail (Aspidoscelis hyperythra), Dulzura kangaroo rat (Dipodomys simulans) (dirt, secondary paved), and deer mouse (Peromyscus maniculatus) (highway only). San Diego pocket mice and cactus mice moved onto dirt roads but not onto a low-use paved road of similar width or onto the highway, indicating they avoidpaved road substrate. Both lizard species moved onto the dirt and secondary paved roads but avoided the rural 2-lane rural highway, indicating they may avoid noise, vibration, or visual disturbance from a steady flow of traffic. Kangaroo rats did not avoid the dirt or secondary paved roads. Overall, dirt and secondary roads were more permeable to species that prefer to forage or bask in open areas of their habitat, rather than under the cover of rocks or shrubs. However, all study species avoided the rural 2-lane highway. Our results suggest that microhabitat use preferences and road substrate help predict species responses to low-use roads,but roads with heavy traffic may deter movement of a much wider range of small animal species.

East Lancashire Hospital Trust creates an open culture paving the way for service improvement 'Below ten thousand'.

PubMed

Tomlinson, Robert

2018-05-01

Reacting to a never event is difficult and often embarrassing for staff involved. East Lancashire Hospitals NHS Trust has demonstrated that treating staff with respect after a never event, creates an open culture that encourages problem solving and service improvement. The approach has allowed learning to be shared and paved the way for the trust to be the first in the UK to launch the patient centric behavioural noise reduction strategy 'Below ten thousand'.

Environmental Assessment: Construct POV Parking Lot Main Gate-Separated at Grand Forks AFB, North Dakota

DTIC Science & Technology

2004-09-01

water quality could be degraded, both in the short-term, during actual construction, and over the long-term due to reduced storm water quality caused by...due to reduced storm water quality caused by the increase of 37 paved area. The short-term effects come from possible erosion contributing to...construction, and over the long-term due to reduced storm water quality caused by the increase of paved area. The short-term effects come from

Architecture Specification for PAVE PILLAR Avionics

DTIC Science & Technology

1987-01-01

PAVE PILLAR system is 99% fault detection. The percent fault detection is determined by the following computation. The number of verified failures de ...reconfiguration or reparameterization requi’red to support manual operations rests w’ith the Mission Supervi’sor. 3.3.8 corm~utr _ De in 3.3.8.1 Hither...1Order Ti.rie Su ’, .S.yStem The Operational Flight Program (OFP) will be de - veloped in accordance with the requirements of the Ada (ANSI/ MIL-STD

Multimaterial 3D Printing of Graphene-Based Electrodes for Electrochemical Energy Storage Using Thermoresponsive Inks.

PubMed

Rocha, Victoria G; García-Tuñón, Esther; Botas, Cristina; Markoulidis, Foivos; Feilden, Ezra; D'Elia, Eleonora; Ni, Na; Shaffer, Milo; Saiz, Eduardo

2017-10-25

The current lifestyles, increasing population, and limited resources result in energy research being at the forefront of worldwide grand challenges, increasing the demand for sustainable and more efficient energy devices. In this context, additive manufacturing brings the possibility of making electrodes and electrical energy storage devices in any desired three-dimensional (3D) shape and dimensions, while preserving the multifunctional properties of the active materials in terms of surface area and conductivity. This paves the way to optimized and more efficient designs for energy devices. Here, we describe how three-dimensional (3D) printing will allow the fabrication of bespoke devices, with complex geometries, tailored to fit specific requirements and applications, by designing water-based thermoresponsive inks to 3D-print different materials in one step, for example, printing the active material precursor (reduced chemically modified graphene (rCMG)) and the current collector (copper) for supercapacitors or anodes for lithium-ion batteries. The formulation of thermoresponsive inks using Pluronic F127 provides an aqueous-based, robust, flexible, and easily upscalable approach. The devices are designed to provide low resistance interface, enhanced electrical properties, mechanical performance, packing of rCMG, and low active material density while facilitating the postprocessing of the multicomponent 3D-printed structures. The electrode materials are selected to match postprocessing conditions. The reduction of the active material (rCMG) and sintering of the current collector (Cu) take place simultaneously. The electrochemical performance of the rCMG-based self-standing binder-free electrode and the two materials coupled rCMG/Cu printed electrode prove the potential of multimaterial printing in energy applications.

Occupational exposure to asphalt fume can cause oxidative DNA damage among road paving workers.

PubMed

Bal, Ceylan; Ağış, Erol R; Büyükşekerci, Murat; Gündüzöz, Meşide; Tutkun, Lütfiye; Yılmaz, Ömer H

2018-06-01

We designed the present study to determine the effect of occupational exposure to asphalt fumes on oxidative status and DNA damage in road paving workers. Sixty road paving workers exposed to asphalt fumes and forty non-exposed control subjects were recruited. Occupational exposure to PAHs was assessed by urinary 1-hydroxypyrene (1-OHP) excretion. Serum thiol disulfide homeostasis (TDH), total oxidant status (TOS) and total antioxidant status (TAS) and urinary 8-hydro-deoxyguanosine (8-OH-dG) level were evaluated by automated colourimetric method. The urinary concentrations of 1-OHP and 8-OH-dG were significantly higher in the exposed group than in the control group (P < 0.001). Disulfide/thiol ratio, TOS, and TAS were also significantly higher for the asphalt workers. A positive correlation existed between urinary 1-OHP and 8-OH-dG, TOS and TAS. Study results indicate that exposure to PAHs induces oxidative stress and causes genotoxic effects in asphalt workers. © 2018 Wiley Periodicals, Inc.

Moving research to practice through partnership: a case study in Asphalt Paving.

PubMed

Chang, Charlotte; Nixon, Laura; Baker, Robin

2015-08-01

Multi-stakeholder partnerships play a critical role in dissemination and implementation in health and safety. To better document and understand construction partnerships that have successfully scaled up effective interventions to protect workers, this case study focused on the collaborative processes of the Asphalt Paving Partnership. In the 1990s, this partnership developed, evaluated, disseminated, and achieved near universal, voluntary adoption of paver engineering controls to reduce exposure to asphalt fumes. We used in-depth interviews (n = 15) and document review in the case study. We describe contextual factors that both facilitated and challenged the formation of the collaboration, central themes and group processes, and research to practice (r2p) outcomes. The Asphalt Paving Partnership offers insight into how multi-stakeholder partnerships in construction can draw upon the strengths of diverse members to improve the dissemination and adoption of health and safety innovations and build a collaborative infrastructure to sustain momentum over time. © 2015 Wiley Periodicals, Inc.

Effects of roads on habitat quality for bears in the southern Appalachians: A long-term study

USGS Publications Warehouse

Reynolds-Hogland, M. J.; Mitchell, M.S.

2007-01-01

We tested the hypothesis that gravel roads, not paved roads, had the largest negative effect on habitat quality for a population of American black bears (Ursus americanus) that lived in a protected area, where vehicle collision was a relatively minimal source of mortality. We also evaluated whether road use by bears differed by sex or age and whether annual variation in hard mast productivity affected the way bears used areas near roads. In addition, we tested previous findings regarding the spatial extent to which roads affected bear behavior negatively. Using summer and fall home ranges for 118 black bears living in the Pisgah Bear Sanctuary in western North Carolina during 1981-2001, we estimated both home-range-scale (2nd-order) and within-home-range-scale (3rd-order) selection for areas within 250, 500, 800, and 1,600 m of paved and gravel roads. All bears avoided areas near gravel roads more than they avoided areas near paved roads during summer and fall for 2nd-order selection and during summer for 3rd-order selection. During fall, only adult females avoided areas near gravel roads more than they avoided areas near paved roads for 3rd-order selection. We found a positive relationship between use of roads by adults and annual variability in hard mast productivity. Overall, bears avoided areas within 800 m of gravel roads. Future research should determine whether avoidance of gravel roads by bears affects bear survival. ?? 2007 American Society of Mammalogists.

One-dimensional nanomaterials for energy storage

NASA Astrophysics Data System (ADS)

Chen, Cheng; Fan, Yuqi; Gu, Jianhang; Wu, Liming; Passerini, Stefano; Mai, Liqiang

2018-03-01

The search for higher energy density, safer, and longer cycling-life energy storage systems is progressing quickly. One-dimensional (1D) nanomaterials have a large length-to-diameter ratio, resulting in their unique electrical, mechanical, magnetic and chemical properties, and have wide applications as electrode materials in different systems. This article reviews the latest hot topics in applying 1D nanomaterials, covering both their synthesis and their applications. 1D nanomaterials can be grouped into the categories: carbon, silicon, metal oxides, and conducting polymers, and we structure our discussion accordingly. Then, we survey the unique properties and application of 1D nanomaterials in batteries and supercapacitors, and provide comments on the progress and advantages of those systems, paving the way for a better understanding of employing 1D nanomaterials for energy storage.

Room temperature ferroelectricity in fluoroperovskite thin films.

PubMed

Yang, Ming; Kc, Amit; Garcia-Castro, A C; Borisov, Pavel; Bousquet, E; Lederman, David; Romero, Aldo H; Cen, Cheng

2017-08-03

The NaMnF 3 fluoride-perovskite has been found, theoretically, to be ferroelectric under epitaxial strain becoming a promising alternative to conventional oxides for multiferroic applications. Nevertheless, this fluoroperovskite has not been experimentally verified to be ferroelectric so far. Here we report signatures of room temperature ferroelectricity observed in perovskite NaMnF 3 thin films grown on SrTiO 3 . Using piezoresponse force microscopy, we studied the evolution of ferroelectric polarization in response to external and built-in electric fields. Density functional theory calculations were also performed to help understand the strong competition between ferroelectric and paraelectric phases as well as the profound influences of strain. These results, together with the magnetic order previously reported in the same material, pave the way to future multiferroic and magnetoelectric investigations in fluoroperovskites.

Phase-selective vanadium dioxide (VO2) nanostructured thin films by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Masina, B. N.; Lafane, S.; Wu, L.; Akande, A. A.; Mwakikunga, B.; Abdelli-Messaci, S.; Kerdja, T.; Forbes, A.

2015-10-01

Thin films of monoclinic nanostructured vanadium dioxide are notoriously difficult to produce in a selective manner. To date, post-annealing, after pulsed laser deposition (PLD), has been used to revert the crystal phase or to remove impurities, and non-glass substrates have been employed, thus reducing the efficacy of the transparency switching. Here, we overcome these limitations in PLD by optimizing a laser-ablation and deposition process through optical imaging of the laser-induced plasma. We report high quality monoclinic rutile-type vanadium dioxide (VO2) (M1) nanoparticles without post-annealing, and on a glass substrate. Our samples demonstrate a reversible metal-to-insulator transition at ˜43 °C, without any doping, paving the way to switchable transparency in optical materials at room temperature.

Antisite Defects in Layered Multiferroic CuCr 0.9In 0.1P 2S 6

DOE PAGES

He, Qian; Belianinov, Alex; Dziaugys, Andrius; ...

2015-10-06

The CuCr 1-xIn xP 2S 6 system represents a large family of metal chalcogenophosphates that are unique and promising candidates for 2D materials with functionalities such as ferroelectricity. We carried out detailed microstructural and chemical characterization of these compounds using aberration-corrected STEM, in order to understand the origin of these different ordering phenomena. Quantitative STEM-HAADF imaging and analysis identified the stacking order of an 8-layer thin flake, which leads to the identification of anti-site In 3+(Cu +) doping. We believe that these findings will pave the way towards understanding the ferroic coupling phenomena in van der Waals lamellar compounds, asmore » well as the potential applications in 2-D electronics.« less

Cool Cities, Cool Planet (LBNL Science at the Theater)

ScienceCinema

Rosenfeld, Arthur; Pomerantz, Melvin; Levinson, Ronnen

2018-06-14

Science at the Theater: Berkeley Lab scientists discuss how cool roofs can cool your building, your city ... and our planet. Arthur Rosenfeld, Professor of Physics Emeritus at UC Berkeley, founded the Berkeley Lab Center for Building Science in 1974. He served on the California Energy Commission from 2000 to 2010 and is commonly referred to as California's godfather of energy efficiency. Melvin Pomerantz is a member of the Heat Island Group at Berkeley Lab. Trained as a physicist at UC Berkeley, he specializes in research on making cooler pavements and evaluating their effects. Ronnen Levinson is a staff scientist at Berkeley Lab and the acting leader of its Heat Island Group. He has developed cool roofing and paving materials and helped bring cool roof requirements into building energy efficiency standards.