Mapping the coupled role of structure and materials in mechanics of platelet-matrix composites

NASA Astrophysics Data System (ADS)

Farzanian, Shafee; Shahsavari, Rouzbeh

2018-03-01

Despite significant progresses on understanding and mimicking the delicate nano/microstructure of biomaterials such as nacre, decoding the indistinguishable merger of materials and structures in controlling the tradeoff in mechanical properties has been long an engineering pursuit. Herein, we focus on an archetype platelet-matrix composite and perform ∼400 nonlinear finite element simulations to decode the complex interplay between various structural features and material characteristics in conferring the balance of mechanical properties. We study various combinatorial models expressed by four key dimensionless parameters, i.e. characteristic platelet length, matrix plasticity, platelet dissimilarity, and overlap offset, whose effects are all condensed in a new unifying parameter, defined as the multiplication of strength, toughness, and stiffness over composite volume. This parameter, which maximizes at a critical characteristic length, controls the transition from intrinsic toughening (matrix plasticity driven without crack growths) to extrinsic toughening phenomena involving progressive crack propagations. This finding, combined with various abstract volumetric and radar plots, will not only shed light on decoupling the complex role of structure and materials on mechanical performance and their trends, but provides important guidelines for designing lightweight staggered platelet-matrix composites while ensuring the best (balance) of their mechanical properties.

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.

Equipment for Nonlinear Photonics Research - Light Control and Image Transmission in Specially-Designed Photonic

DTIC Science & Technology

2014-03-14

photonic graphene”, Nature Material ,13, 57 (2014) ( published online: 10 November 2013 | doi :10.1038/nmat3783) • X. Qi, K.G. Makris, R. El-Ganainy...progress in the proposed research, with several important papers published in leading journals such as Nature Materials , Physics Review Letters...which has been published in Nature Material and Physics Review Letters. Our work was reported in a number of news media as well as featured in PRL

Recent progress concerning the production of controlled highly oriented electrospun nanofibrous arrays

NASA Astrophysics Data System (ADS)

Manea, L. R.; Hristian, L.; Leon, A. L.; Popa, A.

2016-08-01

Among the foreground domains of all the research-development programs at national and international level, a special place is occupied by that concerning the nanosciences, nanotechnologies, new materials and technologies. Electrospinning found a well-deserved place in this space, offering the preparation of nanomaterials with distinctive properties and applications in medicine, environment, photonic sensors, filters, etc. These multiple applications are generated by the fact that the electrospinning technology makes available the production of nanofibers with controllable characteristics (length, porosity, density, and mechanical characteristics), complexity and architecture. The apparition of 3D printing technology favors the production of complex nanofibrous structures, controlled assembly, self-assembly of electrospun nanofibers for the production of scaffolds used in various medical applications. The architecture of fibrous deposits has a special influence on the subsequent development of the cells of the reconstructed organism. The present work proposes to study of recent progress concerning the production of controlled highly oriented electrospun nanofibrous arrays and progress in research on the production of complex 2D and 3D structures.

Wood-Based Nanotechnologies toward Sustainability.

PubMed

Jiang, Feng; Li, Tian; Li, Yiju; Zhang, Ying; Gong, Amy; Dai, Jiaqi; Hitz, Emily; Luo, Wei; Hu, Liangbing

2018-01-01

With over 30% global land coverage, the forest is one of nature's most generous gifts to human beings, providing shelters and materials for all living beings. Apart from being sustainable, renewable, and biodegradable, wood and its derivative materials are also extremely fascinating from a materials aspect, with numerous advantages including porous and hierarchical structure, excellent mechanical performance, and versatile chemistry. Here, strategies for designing novel wood-based materials via advanced nanotechnologies are summarized, including both the controllable bottom-up assembly from the highly crystalline nanocellulose building block and the more efficient top-down approaches directly from wood. Beyond material design, recent advances regarding the sustainable applications of these novel wood-based materials are also presented, focusing on areas that are traditionally dominated by man-made nonrenewable materials such as plastic, glass, and metals, as well as more advanced applications in the areas of energy storage, wastewater treatment and solar-steam-assisted desalination. With all recent progress pertaining to materials' design and sustainable applications presented, a vision for the future engineering of wood-based materials to promote continuous and healthy progress toward true sustainability is outlined. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controlling the shapes of coated silicon substrates via magnetic fields, a progress report

NASA Astrophysics Data System (ADS)

Ulmer, Melville P.; Coppejans, Rocco; Buchholz, David B.; Cao, Jian; Wang, Xiaoli; Mercado, Alejandro M.; Qian, Jun; Assoufid, Lahsen; O'Donnell, Allison E.; Condron, Kyle S.; Harpt, Benjamin E.

2017-08-01

We describe our progress in developing a method for correcting residual figure errors in X-ray mirrors. The technology has applications to both synchrotron radiation beamlines and X-ray astronomy. Our concept is to develop mirrors that are on the order of a millimeter thick. A magnetic smart material (MSM) is deposited onto the mirror substrate (silicon) and coated with a magnetically hard material. The shape of the mirror can be controlled by applying an external magnetic field to the mirror. This causes the MSM to expand or contract, thereby applying a magnetostrictive stress to the mirror and changing its shape. The shape change is maintained after the field has been removed by the magnetic hard material, which retains part of the field and prevents the MSM from relaxing. Here we present the results of shaping 200 µm thick silicon (100) 14 × 2 mm cantilevers and 50 × 50 × 0.1 mm substrates. We demonstrate that not only can a sizable deflection be created, but it can also be retained for ˜ 60 hours.

Separation anxiety: Stress, tension and cytokinesis

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

Mohan, Krithika; Iglesias, Pablo A., E-mail: pi@jhu.edu; Robinson, Douglas N., E-mail: dnr@jhmi.edu

Cytokinesis, the physical separation of a mother cell into two daughter cells, progresses through a series of well-defined changes in morphology. These changes involve distinct biochemical and mechanical processes. Here, we review the mechanical features of cells during cytokinesis, discussing both the material properties as well as sources of stresses, both active and passive, which lead to the observed changes in morphology. We also describe a mechanosensory feedback control system that regulates protein localization and shape progression during cytokinesis. -- Highlights: Black-Right-Pointing-Pointer Cytokinesis progresses through three distinct mechanical phases. Black-Right-Pointing-Pointer Cortical tension initially resists deformation of mother cell. Black-Right-Pointing-Pointer Latemore » in cytokinesis, cortical tension provides stress, enabling furrow ingression. Black-Right-Pointing-Pointer A mechanosensory feedback control system regulates cytokinesis.« less

Pre-Statistical Process Control: Making Numbers Count! JobLink Winning at Work Instructor's Manual, Module 3.

ERIC Educational Resources Information Center

Coast Community Coll. District, Costa Mesa, CA.

This instructor's manual for workplace trainers contains the materials required to conduct a course in pre-statistical process control. The course consists of six lessons for workers and two lessons for supervisors that discuss the following: concepts taught in the six lessons; workers' progress in the individual lessons; and strategies for…

Factors Influencing Progressive Failure Analysis Predictions for Laminated Composite Structure

NASA Technical Reports Server (NTRS)

Knight, Norman F., Jr.

2008-01-01

Progressive failure material modeling methods used for structural analysis including failure initiation and material degradation are presented. Different failure initiation criteria and material degradation models are described that define progressive failure formulations. These progressive failure formulations are implemented in a user-defined material model for use with a nonlinear finite element analysis tool. The failure initiation criteria include the maximum stress criteria, maximum strain criteria, the Tsai-Wu failure polynomial, and the Hashin criteria. The material degradation model is based on the ply-discounting approach where the local material constitutive coefficients are degraded. Applications and extensions of the progressive failure analysis material model address two-dimensional plate and shell finite elements and three-dimensional solid finite elements. Implementation details are described in the present paper. Parametric studies for laminated composite structures are discussed to illustrate the features of the progressive failure modeling methods that have been implemented and to demonstrate their influence on progressive failure analysis predictions.

Polaris-P Year 2 Report

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

Kaye, Willy; Boucher, Andy

The Polaris-P is under development at H3D for the Gamma-Ray Imaging Spectrometers for Nuclear Materials Accounting and Controls Phase II SBIR from the DOE. This report will summarize the progress made during the second year of the project.

Soft Robotic Grippers.

PubMed

Shintake, Jun; Cacucciolo, Vito; Floreano, Dario; Shea, Herbert

2018-05-07

Advances in soft robotics, materials science, and stretchable electronics have enabled rapid progress in soft grippers. Here, a critical overview of soft robotic grippers is presented, covering different material sets, physical principles, and device architectures. Soft gripping can be categorized into three technologies, enabling grasping by: a) actuation, b) controlled stiffness, and c) controlled adhesion. A comprehensive review of each type is presented. Compared to rigid grippers, end-effectors fabricated from flexible and soft components can often grasp or manipulate a larger variety of objects. Such grippers are an example of morphological computation, where control complexity is greatly reduced by material softness and mechanical compliance. Advanced materials and soft components, in particular silicone elastomers, shape memory materials, and active polymers and gels, are increasingly investigated for the design of lighter, simpler, and more universal grippers, using the inherent functionality of the materials. Embedding stretchable distributed sensors in or on soft grippers greatly enhances the ways in which the grippers interact with objects. Challenges for soft grippers include miniaturization, robustness, speed, integration of sensing, and control. Improved materials, processing methods, and sensing play an important role in future research. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Artificially Engineered Protein Polymers.

PubMed

Yang, Yun Jung; Holmberg, Angela L; Olsen, Bradley D

2017-06-07

Modern polymer science increasingly requires precise control over macromolecular structure and properties for engineering advanced materials and biomedical systems. The application of biological processes to design and synthesize artificial protein polymers offers a means for furthering macromolecular tunability, enabling polymers with dispersities of ∼1.0 and monomer-level sequence control. Taking inspiration from materials evolved in nature, scientists have created modular building blocks with simplified monomer sequences that replicate the function of natural systems. The corresponding protein engineering toolbox has enabled the systematic development of complex functional polymeric materials across areas as diverse as adhesives, responsive polymers, and medical materials. This review discusses the natural proteins that have inspired the development of key building blocks for protein polymer engineering and the function of these elements in material design. The prospects and progress for scalable commercialization of protein polymers are reviewed, discussing both technology needs and opportunities.

Cybermaterials: materials by design and accelerated insertion of materials

NASA Astrophysics Data System (ADS)

Xiong, Wei; Olson, Gregory B.

2016-02-01

Cybermaterials innovation entails an integration of Materials by Design and accelerated insertion of materials (AIM), which transfers studio ideation into industrial manufacturing. By assembling a hierarchical architecture of integrated computational materials design (ICMD) based on materials genomic fundamental databases, the ICMD mechanistic design models accelerate innovation. We here review progress in the development of linkage models of the process-structure-property-performance paradigm, as well as related design accelerating tools. Extending the materials development capability based on phase-level structural control requires more fundamental investment at the level of the Materials Genome, with focus on improving applicable parametric design models and constructing high-quality databases. Future opportunities in materials genomic research serving both Materials by Design and AIM are addressed.

User-Defined Material Model for Progressive Failure Analysis

NASA Technical Reports Server (NTRS)

Knight, Norman F. Jr.; Reeder, James R. (Technical Monitor)

2006-01-01

An overview of different types of composite material system architectures and a brief review of progressive failure material modeling methods used for structural analysis including failure initiation and material degradation are presented. Different failure initiation criteria and material degradation models are described that define progressive failure formulations. These progressive failure formulations are implemented in a user-defined material model (or UMAT) for use with the ABAQUS/Standard1 nonlinear finite element analysis tool. The failure initiation criteria include the maximum stress criteria, maximum strain criteria, the Tsai-Wu failure polynomial, and the Hashin criteria. The material degradation model is based on the ply-discounting approach where the local material constitutive coefficients are degraded. Applications and extensions of the progressive failure analysis material model address two-dimensional plate and shell finite elements and three-dimensional solid finite elements. Implementation details and use of the UMAT subroutine are described in the present paper. Parametric studies for composite structures are discussed to illustrate the features of the progressive failure modeling methods that have been implemented.

Woodworking Technology.

ERIC Educational Resources Information Center

Kirk, Albert S.; And Others

1991-01-01

Three articles discuss the importance of wood processing to manufacturing and construction industries and the need for progressive change in the curriculum; the evolution of wood-based synthetic panel materials; and the technological advances in the computer control of machine tools and their incorporation into wood technology curricula. (JOW)

Continuation of epidermal growth factor receptor tyrosine kinase inhibitor treatment prolongs disease control in non-small-cell lung cancers with acquired resistance to EGFR tyrosine kinase inhibitors

PubMed Central

Chen, Qi; Quan, Qi; Ding, Lingyu; Hong, Xiangchan; Zhou, Ningning; Liang, Ying; Wu, Haiying

2015-01-01

Objectives Patients with non-small-cell lung cancer (NSCLC) develop acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) after tumor regression. No approved targeted therapies are currently available after initial EGFR TKI treatment. This study investigated the efficacy of continuing EGFR TKI therapy with local treatments for patients with NSCLC and local progression or minimal/slow progression on TKI therapy. Materials and Methods Fifty-five patients with NSCLC treated with EGFR TKIs and developed acquired resistance to the drug were included. Initial response to target therapy, median progression free survival (PFS1), progression pattern, and first progression site were assessed. Median progression free survival to physician assessment progression (PFS2) and difference between PFS1 and PFS2 (PFS difference) were also recorded. Results and Conclusion PFS1 was 11.2 months, PFS2 was 20.3 months, and PFS difference was 8.3 months. Nineteen patients (34.5%) who manifested progression received local therapy, and 16 (28.6%) underwent rebiopsy after progression with six positive EGFR T790M mutations detected. Cox proportional hazards regression model showed that only the first line of treatment was significantly correlated with PFS difference. NSCLC patients with acquired resistance to EGFR TKIs could benefit from the same TKI therapy through months to years of disease control. PMID:26172562

Micro- and nano-mechanics in China: A brief review of recent progress and perspectives

NASA Astrophysics Data System (ADS)

Xu, ZhiPing; Zheng, QuanShui

2018-07-01

The past three decades have witnessed the explosion of nanoscience and technology, where notable research efforts have been made in synthesizing nanomaterials and controlling nanostructures of bulk materials. The uncovered mechanical behaviors of structures and materials with reduced sizes and dimensions pose open questions to the community of mechanicians, which expand the framework of continuum mechanics by advancing the theory, as well as modeling and experimental tools. Researchers in China have been actively involved into this exciting area, making remarkable contributions to the understanding of nanoscale mechanical processes, the development of multi-scale, multi-field modeling and experimental techniques to resolve the processing-microstructures-properties relationship of materials, and the interdisciplinary studies that broaden the subjects of mechanics. This article reviews selected progress made by this community, with the aim to clarify the key concepts, methods and applications of micro- and nano-mechanics, and to outline the perspectives in this fast-evolving field.

Influence of removing excess of resin-based materials applied to eroded enamel on the resistance to erosive challenge.

PubMed

Tereza, Guida Paola Genovez; de Oliveira, Gabriela Cristina; de Andrade Moreira Machado, Maria Aparecida; de Oliveira, Thais Marchine; da Silva, Thiago Cruvinel; Rios, Daniela

2016-04-01

The aim of this study was to evaluate the effect of removing excess of resin-based materials applied to eroded enamel, subjected to erosive challenge. Bovine enamel blocks were immersed in HCl 0.01M, pH 2.3, for 30s under agitation at 50 rpm in room temperature, in order to form a softened erosion lesion. The blocks were then randomly divided into eight groups (n=12) and treated as follows: Cn- and Ce-control without treatment, Hn- and He-fissure resin sealant (Helioseal Clear(®)), An- and Ae-self-etch adhesive (Adhese(®)), In- and Ie-infiltrant (Icon(®)); being n-with excess removal and e-without excess removal of the material. After application of the materials, the blocks were immersed in HCl for 2 min, followed by immersion in artificial saliva for 120 min. This cycle was repeated four times a day for five days. Material thickness and enamel wear were assessed using profilometry. Data were analyzed by two-way ANOVA and Tukey's test (P<0.05). Groups He, Ae, and Ie resulted in the formation of a layer of material over enamel, being similar effective in inhibiting erosion progression (P>0.05). Groups Hn, An, and In (with excess removal) were similar to controls (Cn, Ce) and resulted in near enamel loss after application and after erosive challenge (P>0.05). Resin-based materials are able to protect enamel against erosion only when they are present over enamel, as a physical barrier. The resin-based materials demonstrated potential to prevent the progression of erosion lesions when the material remains on the dental surface. Copyright © 2016 Elsevier Ltd. All rights reserved.

How does negative emotion cause false memories?

PubMed

Brainerd, C J; Stein, L M; Silveira, R A; Rohenkohl, G; Reyna, V F

2008-09-01

Remembering negative events can stimulate high levels of false memory, relative to remembering neutral events. In experiments in which the emotional valence of encoded materials was manipulated with their arousal levels controlled, valence produced a continuum of memory falsification. Falsification was highest for negative materials, intermediate for neutral materials, and lowest for positive materials. Conjoint-recognition analysis produced a simple process-level explanation: As one progresses from positive to neutral to negative valence, false memory increases because (a) the perceived meaning resemblance between false and true items increases and (b) subjects are less able to use verbatim memories of true items to suppress errors.

Recent progress in stem cell differentiation directed by material and mechanical cues.

PubMed

Lin, Xunxun; Shi, Yuan; Cao, Yilin; Liu, Wei

2016-02-02

Stem cells play essential roles in tissue regeneration in vivo via specific lineage differentiation induced by environmental factors. In the past, biochemical signals were the focus of induced stem cell differentiation. As reported by Engler et al (2006 Cell 126 677-89), biophysical signal mediated stem cell differentiation could also serve as an important inducer. With the advancement of material science, it becomes a possible strategy to generate active biophysical signals for directing stem cell fate through specially designed material microstructures. In the past five years, significant progress has been made in this field, and these designed biophysical signals include material elasticity/rigidity, micropatterned structure, extracellular matrix (ECM) coated materials, material transmitted extracellular mechanical force etc. A large number of investigations involved material directed differentiation of mesenchymal stem cells, neural stem/progenitor cells, adipose derived stem cells, hematopoietic stem/progenitor cells, embryonic stem cells and other cells. Hydrogel based materials were commonly used to create varied mechanical properties via modifying the ratio of different components, crosslinking levels, matrix concentration and conjugation with other components. Among them, polyacrylamide (PAM) and polydimethylsiloxane (PDMS) hydrogels remained the major types of material. Specially designed micropatterning was not only able to create a unique topographical surface to control cell shape, alignment, cell-cell and cell-matrix contact for basic stem cell biology study, but also could be integrated with 3D bioprinting to generate micropattered 3D structure and thus to induce stem cell based tissue regeneration. ECM coating on a specific topographical structure was capable of inducing even more specific and potent stem cell differentiation along with soluble factors and mechanical force. The article overviews the progress of the past five years in this particular field.

Progress in aeronautical research and technology applicable to civil air transports

NASA Technical Reports Server (NTRS)

Bower, R. E.

1981-01-01

Recent progress in the aeronautical research and technology program being conducted by the United States National Aeronautics and Space Administration is discussed. Emphasis is on computational capability, new testing facilities, drag reduction, turbofan and turboprop propulsion, noise, composite materials, active controls, integrated avionics, cockpit displays, flight management, and operating problems. It is shown that this technology is significantly impacting the efficiency of the new civil air transports. The excitement of emerging research promises even greater benefits to future aircraft developments.

Advances in nonlinear optical materials and devices

NASA Technical Reports Server (NTRS)

Byer, Robert L.

1991-01-01

The recent progress in the application of nonlinear techniques to extend the frequency of laser sources has come from the joint progress in laser sources and in nonlinear materials. A brief summary of the progress in diode pumped solid state lasers is followed by an overview of progress in nonlinear frequency extension by harmonic generation and parametric processes. Improved nonlinear materials including bulk crystals, quasiphasematched interactions, guided wave devices, and quantum well intersubband studies are discussed with the idea of identifying areas of future progress in nonlinear materials and devices.

The Evolution of Marketing in Education.

ERIC Educational Resources Information Center

Knight, Brent

1982-01-01

Looks at the progression of educational institutions through the five stages of Kotler's marketing process. Identifies anticipated changes and three activities critical for meeting the marketing challenge: research to predict consumer habits, attitudes, and needs; material and research development changes; and strict quality control and relevance…

Fossil energy program

NASA Astrophysics Data System (ADS)

McNeese, L. E.

1981-12-01

The progress made during the period from July 1 through September 30 for the Oak Ridge National Laboratory research and development projects in support of the increased utilization of coal and other fossil fuels as sources of clean energy is reported. The following topics are discussed: coal conversion development, chemical research and development, materials technology, fossil energy materials program, liquefaction projects, component development, process analysis, environmental control technology, atmospheric fluidized bed combustion, underground coal gasification, coal preparation and waste utilization.

Breakthrough and future: nanoscale controls of compositions, morphologies, and mesochannel orientations toward advanced mesoporous materials.

PubMed

Yamauchi, Yusuke; Suzuki, Norihiro; Radhakrishnan, Logudurai; Wang, Liang

2009-01-01

Currently, ordered mesoporous materials prepared through the self-assembly of surfactants have attracted growing interests owing to their special properties, including uniform mesopores and a high specific surface area. Here we focus on fine controls of compositions, morphologies, mesochannel orientations which are important factors for design of mesoporous materials with new functionalities. This Review describes our recent progress toward advanced mesoporous materials. Mesoporous materials now include a variety of inorganic-based materials, for example, transition-metal oxides, carbons, inorganic-organic hybrid materials, polymers, and even metals. Mesoporous metals with metallic frameworks can be produced by using surfactant-based synthesis with electrochemical methods. Owing to their metallic frameworks, mesoporous metals with high electroconductivity and high surface areas hold promise for a wide range of potential applications, such as electronic devices, magnetic recording media, and metal catalysts. Fabrication of mesoporous materials with controllable morphologies is also one of the main subjects in this rapidly developing research field. Mesoporous materials in the form of films, spheres, fibers, and tubes have been obtained by various synthetic processes such as evaporation-mediated direct templating (EDIT), spray-dried techniques, and collaboration with hard-templates such as porous anodic alumina and polymer membranes. Furthermore, we have developed several approaches for orientation controls of 1D mesochannels. The macroscopic-scale controls of mesochannels are important for innovative applications such as molecular-scale devices and electrodes with enhanced diffusions of guest species. Copyright 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Advanced electromagnetic methods for aerospace vehicles

NASA Technical Reports Server (NTRS)

Balanis, Constantine A.; Sun, Weimin; El-Sharawy, El-Budawy; Aberle, James T.; Birtcher, Craig R.; Peng, Jian; Tirkas, Panayiotis A.; Andrew, William V.; Kokotoff, David; Zavosh, Frank

1993-01-01

The Advanced Helicopter Electromagnetics (AHE) Industrial Associates Program has fruitfully completed its fourth year. Under the support of the AHE members and the joint effort of the research team, new and significant progress has been achieved in the year. Following the recommendations by the Advisory Task Force, the research effort is placed on more practical helicopter electromagnetic problems, such as HF antennas, composite materials, and antenna efficiencies. In this annual report, the main topics to be addressed include composite materials and antenna technology. The research work on each topic has been driven by the AHE consortium members' interests and needs. The remarkable achievements and progresses in each subject is reported respectively in individual sections of the report. The work in the area of composite materials includes: modeling of low conductivity composite materials by using Green's function approach; guidelines for composite material modeling by using the Green's function approach in the NEC code; development of 3-D volume mesh generator for modeling thick and volumetric dielectrics by using FD-TD method; modeling antenna elements mounted on a composite Comanche tail stabilizer; and antenna pattern control and efficiency estimate for a horn antenna loaded with composite dielectric materials.

New Technologies and Materials for Enhanced Damage and Fire Tolerance of Naval Vessels

DTIC Science & Technology

2011-02-01

have already been used on naval vessels. However, their incorporation into fire and damage control systems has not progressed past the prototype...have an important role to play in enhancing fire suppression capabilities onboard ships. One is ventilation control . It can be used to isolate a...complicated than those for a dedicated system. Positive pressure ventilation and the use of the ship board HVAC trunking to control the spread of smoke

Cognitive and Language Deficits in Multiple Sclerosis: Comparison of Relapsing Remitting and Secondary Progressive Subtypes

PubMed Central

Ntoskou, Katerina; Messinis, Lambros; Nasios, Grigorios; Martzoukou, Maria; Makris, Giorgos; Panagiotopoulos, Elias; Papathanasopoulos, Panagiotis

2018-01-01

Objective: The objective of this study was to investigate the pattern and severity of cognitive and language impairment in Greek patients with Relapsing-remitting (RRMS) and Secondary Progressive Multiple Sclerosis (SPMS), relative to control participants. Method: A prospective study was conducted in 27 patients with multiple sclerosis (PwMS), (N= 15) with RRMS, (N= 12) with SPMS, and (N= 12) healthy controls. All participants were assessed with a flexible comprehensive neuropsychological – language battery of tests that have been standardized in Greece and validated in Greek MS patients. They were also assessed on measures of disability (Expanded Disability Status Scale; EDSS), fatigue (Fatigue Severity Scale; FSS) and depression (Beck Depression Inventory - fast screen; BDI-FS). Results: Our results revealed that groups were well matched on baseline demographic and clinical characteristics. The two clinical groups (RRMS; SPMS) did not differ on overall global cognitive impairment but differed in the initial encoding of verbal material, mental processing speed, response inhibition and set-shifting. RRMS patients differed from controls in the initial encoding of verbal material, learning curve, delayed recall of verbal information, processing speed, and response inhibition. SPMS patients differed in all utilized measures compared to controls. Moreover, we noted increased impairment frequency on individualized measures in the progressive SPMS group. Conclusion: We conclude that MS patients, irrespective of clinical subtype, have cognitive deficits compared to healthy participants, which become increasingly worse when they convert from RRMS to SPMS.On the contrary,the pattern of impairment remains relatively stable. PMID:29576812

Semiconductor technology program: Progress briefs

NASA Technical Reports Server (NTRS)

Galloway, K. F.; Scace, R. I.; Walters, E. J.

1981-01-01

Measurement technology for semiconductor materials, process control, and devices, is discussed. Silicon and silicon based devices are emphasized. Highlighted activities include semiinsulating GaAs characterization, an automatic scanning spectroscopic ellipsometer, linewidth measurement and coherence, bandgap narrowing effects in silicon, the evaluation of electrical linewidth uniformity, and arsenicomplanted profiles in silicon.

Effects of a classroom intervention with spatial play materials on children's object and viewer transformation abilities.

PubMed

Vander Heyden, Karin M; Huizinga, Mariette; Jolles, Jelle

2017-02-01

Children practice their spatial skills when playing with spatial toys, such as construction materials, board games, and puzzles. Sex and SES differences are observed in the engagement in such spatial play activities at home, which relate to individual differences in spatial performance. The current study investigated the effects of explicitly providing spatial play activities in the school setting on different types of spatial ability. We presented 8- to 10-year-old children with a short and easy-to-adopt classroom intervention comprising a set of different spatial play materials. The design involved a pretest-posttest comparison between the intervention group (n = 70) and a control group without intervention (n = 70). Effects were examined on object transformation ability (i.e., a paper-and-pencil mental rotation and paper folding task) and viewer transformation ability (i.e., a hands-on 3D spatial perspective-taking task). Results showed specific effects: there were no differences between the intervention and control group in progress on the two object transformation tasks. Substantial improvements were found for the intervention group compared to the control group on the viewer transformation task. Training progress was not related to sex and socioeconomic background of the child. These findings support the value of spatial play in the classroom for the spatial development of children between 8 and 10 years of age. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Recent development, applications, and perspectives of mesoporous silica particles in medicine and biotechnology.

PubMed

Pasqua, Luigi; Cundari, Sante; Ceresa, Cecilia; Cavaletti, Guido

2009-01-01

Mesoporous silica particles (MSP) are a new development in nanotechnology. Covalent modification of the surface of the silica is possible both on the internal pore and on the external particle surface. It allows the design of functional nanostructured materials with properties of organic, biological and inorganic components. Research and development are ongoing on the MSP, which have applications in catalysis, drug delivery and imaging. The most recent and interesting advancements in size, morphology control and surface functionalization of MSP have enhanced the biocompatibility of these materials with high surface areas and pore volumes. In the last 5 years several reports have demonstrated that MSP can be efficiently internalized using in vitro and animal models. The functionalization of MSP with organic moieties or other nanostructures brings controlled release and molecular recognition capabilities to these mesoporous materials for drug/gene delivery and sensing applications, respectively. Herein, we review recent research progress on the design of functional MSP materials with various mechanisms of targeting and controlled release.

Bio-Optics and Bio-Inspired Optical Materials.

PubMed

Tadepalli, Sirimuvva; Slocik, Joseph M; Gupta, Maneesh K; Naik, Rajesh R; Singamaneni, Srikanth

2017-10-25

Through the use of the limited materials palette, optimally designed micro- and nanostructures, and tightly regulated processes, nature demonstrates exquisite control of light-matter interactions at various length scales. In fact, control of light-matter interactions is an important element in the evolutionary arms race and has led to highly engineered optical materials and systems. In this review, we present a detailed summary of various optical effects found in nature with a particular emphasis on the materials and optical design aspects responsible for their optical functionality. Using several representative examples, we discuss various optical phenomena, including absorption and transparency, diffraction, interference, reflection and antireflection, scattering, light harvesting, wave guiding and lensing, camouflage, and bioluminescence, that are responsible for the unique optical properties of materials and structures found in nature and biology. Great strides in understanding the design principles adapted by nature have led to a tremendous progress in realizing biomimetic and bioinspired optical materials and photonic devices. We discuss the various micro- and nanofabrication techniques that have been employed for realizing advanced biomimetic optical structures.

[RESEARCH PROGRESS OF THREE-DIMENSIONAL PRINTING POROUS SCAFFOLDS FOR BONE TISSUE ENGINEERING].

PubMed

Wu, Tianqi; Yang, Chunxi

2016-04-01

To summarize the research progress of several three-dimensional (3-D)-printing scaffold materials in bone tissue engineering. The recent domestic and international articles about 3-D printing scaffold materials were reviewed and summarized. Compared with conventional manufacturing methods, 3-D printing has distinctive advantages, such as enhancing the controllability of the structure and increasing the productivity. In addition to the traditional metal and ceramic scaffolds, 3-D printing scaffolds carrying seeding cells and tissue factors as well as scaffolds filling particular drugs for special need have been paid more and more attention. The development of 3-D printing porous scaffolds have revealed new perspectives in bone repairing. But it is still at the initial stage, more basic and clinical researches are still needed.

Exploiting Novel Radiation-Induced Electromagnetic Material Changes for Remote Detection and Monitoring: Final Progress Report

DTIC Science & Technology

2016-04-01

research has been that the feedback amplifiers are sensitive to many controllable and some, as of yet, uncontrollable environmental factors. Many of these...shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number...41  3.2.3  Design , construction, and testing of GEN-1 feedback amplifier

Differential Expression of Social Dominance as a Function of Age and Maltreatment Experience

ERIC Educational Resources Information Center

Teisl, Michael; Rogosch, Fred A.; Oshri, Assaf; Cicchetti, Dante

2012-01-01

Recent perspectives on social dominance in normative populations have suggested a developmental progression from using primarily coercive strategies to incorporation of more socially competent strategies to attain material and social resources. Parental influences on the resource control strategies children use have been proposed but not…

Development progress of the Materials Analysis and Particle Probe

NASA Astrophysics Data System (ADS)

Lucia, M.; Kaita, R.; Majeski, R.; Bedoya, F.; Allain, J. P.; Boyle, D. P.; Schmitt, J. C.; Onge, D. A. St.

2014-11-01

The Materials Analysis and Particle Probe (MAPP) is a compact in vacuo surface science diagnostic, designed to provide in situ surface characterization of plasma facing components in a tokamak environment. MAPP has been implemented for operation on the Lithium Tokamak Experiment at Princeton Plasma Physics Laboratory (PPPL), where all control and analysis systems are currently under development for full remote operation. Control systems include vacuum management, instrument power, and translational/rotational probe drive. Analysis systems include onboard Langmuir probes and all components required for x-ray photoelectron spectroscopy, low-energy ion scattering spectroscopy, direct recoil spectroscopy, and thermal desorption spectroscopy surface analysis techniques.

Development progress of the Materials Analysis and Particle Probe.

PubMed

Lucia, M; Kaita, R; Majeski, R; Bedoya, F; Allain, J P; Boyle, D P; Schmitt, J C; Onge, D A St

2014-11-01

The Materials Analysis and Particle Probe (MAPP) is a compact in vacuo surface science diagnostic, designed to provide in situ surface characterization of plasma facing components in a tokamak environment. MAPP has been implemented for operation on the Lithium Tokamak Experiment at Princeton Plasma Physics Laboratory (PPPL), where all control and analysis systems are currently under development for full remote operation. Control systems include vacuum management, instrument power, and translational/rotational probe drive. Analysis systems include onboard Langmuir probes and all components required for x-ray photoelectron spectroscopy, low-energy ion scattering spectroscopy, direct recoil spectroscopy, and thermal desorption spectroscopy surface analysis techniques.

Fuel efficiency through new airframe technology

NASA Technical Reports Server (NTRS)

Leonard, R. W.

1982-01-01

In its Aircraft Energy Efficiency Program, NASA has expended approximately 200 million dollars toward development and application of advanced airframe technologies to United States's commercial transports. United States manufacturers have already been given a significant boost toward early application of advanced composite materials to control surface and empennage structures and toward selected applications of active controls and advanced aerodynamic concepts. In addition, significant progress in definition and development of innovative, but realistic systems for laminar flow control over the wings of future transports has already been made.

Emerging ferroelectric transistors with nanoscale channel materials: the possibilities, the limitations

NASA Astrophysics Data System (ADS)

Hong, Xia

2016-03-01

Combining the nonvolatile, locally switchable polarization field of a ferroelectric thin film with a nanoscale electronic material in a field effect transistor structure offers the opportunity to examine and control a rich variety of mesoscopic phenomena and interface coupling. It is also possible to introduce new phases and functionalities into these hybrid systems through rational design. This paper reviews two rapidly progressing branches in the field of ferroelectric transistors, which employ two distinct classes of nanoscale electronic materials as the conducting channel, the two-dimensional (2D) electron gas graphene and the strongly correlated transition metal oxide thin films. The topics covered include the basic device physics, novel phenomena emerging in the hybrid systems, critical mechanisms that control the magnitude and stability of the field effect modulation and the mobility of the channel material, potential device applications, and the performance limitations of these devices due to the complex interface interactions and challenges in achieving controlled materials properties. Possible future directions for this field are also outlined, including local ferroelectric gate control via nanoscale domain patterning and incorporating other emergent materials in this device concept, such as the simple binary ferroelectrics, layered 2D transition metal dichalcogenides, and the 4d and 5d heavy metal compounds with strong spin-orbit coupling.

Progress in piezo-phototronic effect modulated photovoltaics.

PubMed

Que, Miaoling; Zhou, Ranran; Wang, Xiandi; Yuan, Zuqing; Hu, Guofeng; Pan, Caofeng

2016-11-02

Wurtzite structured materials, like ZnO, GaN, CdS, and InN, simultaneously possess semiconductor and piezoelectric properties. The inner-crystal piezopotential induced by external strain can effectively tune/control the carrier generation, transport and separation/combination processes at the metal-semiconductor contact or p-n junction, which is called the piezo-phototronic effect. This effect can efficiently enhance the performance of photovoltaic devices based on piezoelectric semiconductor materials by utilizing the piezo-polarization charges at the junction induced by straining, which can modulate the energy band of the piezoelectric material and then accelerate or prevent the separation process of the photon-generated electrons and vacancies. This paper introduces the fundamental physics principles of the piezo-phototronic effect, and reviews recent progress in piezo-phototronic effect enhanced solar cells, including solar cells based on semiconductor nanowire, organic/inorganic materials, quantum dots, and perovskite. The piezo-phototronic effect is suggested as a suitable basis for the development of an innovative method to enhance the performance of solar cells based on piezoelectric semiconductors by applied extrinsic strains, which might be appropriate for fundamental research and potential applications in various areas of optoelectronics.

Progress in piezo-phototronic effect modulated photovoltaics

NASA Astrophysics Data System (ADS)

Que, Miaoling; Zhou, Ranran; Wang, Xiandi; Yuan, Zuqing; Hu, Guofeng; Pan, Caofeng

2016-11-01

Wurtzite structured materials, like ZnO, GaN, CdS, and InN, simultaneously possess semiconductor and piezoelectric properties. The inner-crystal piezopotential induced by external strain can effectively tune/control the carrier generation, transport and separation/combination processes at the metal-semiconductor contact or p-n junction, which is called the piezo-phototronic effect. This effect can efficiently enhance the performance of photovoltaic devices based on piezoelectric semiconductor materials by utilizing the piezo-polarization charges at the junction induced by straining, which can modulate the energy band of the piezoelectric material and then accelerate or prevent the separation process of the photon-generated electrons and vacancies. This paper introduces the fundamental physics principles of the piezo-phototronic effect, and reviews recent progress in piezo-phototronic effect enhanced solar cells, including solar cells based on semiconductor nanowire, organic/inorganic materials, quantum dots, and perovskite. The piezo-phototronic effect is suggested as a suitable basis for the development of an innovative method to enhance the performance of solar cells based on piezoelectric semiconductors by applied extrinsic strains, which might be appropriate for fundamental research and potential applications in various areas of optoelectronics.

Synthesis of nanostructured materials in inverse miniemulsions and their applications.

PubMed

Cao, Zhihai; Ziener, Ulrich

2013-11-07

Polymeric nanogels, inorganic nanoparticles, and organic-inorganic hybrid nanoparticles can be prepared via the inverse miniemulsion technique. Hydrophilic functional cargos, such as proteins, DNA, and macromolecular fluoresceins, may be conveniently encapsulated in these nanostructured materials. In this review, the progress of inverse miniemulsions since 2000 is summarized on the basis of the types of reactions carried out in inverse miniemulsions, including conventional free radical polymerization, controlled/living radical polymerization, polycondensation, polyaddition, anionic polymerization, catalytic oxidation reaction, sol-gel process, and precipitation reaction of inorganic precursors. In addition, the applications of the nanostructured materials synthesized in inverse miniemulsions are also reviewed.

FY2011 Annual Progress Report for Propulsion Materials

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

Davis, Patrick B.; Schutte, Carol L.; Gibbs, Jerry L.

Annual Progress Report for Propulsion Materials focusing on enabling and innovative materials technologies that are critical in improving the efficiency of advanced engines by providing enabling materials support for combustion, hybrid, and power electronics development.

Recent progress in mesoporous titania materials: adjusting morphology for innovative applications.

PubMed

Vivero-Escoto, Juan L; Chiang, Ya-Dong; Wu, Kevin; Yamauchi, Yusuke

2012-02-01

This review article summarizes recent developments in mesoporous titania materials, particularly in the fields of morphology control and applications. We first briefly introduce the history of mesoporous titania materials and then review several synthesis approaches. Currently, mesoporous titania nanoparticles (MTNs) have attracted much attention in various fields, such as medicine, catalysis, separation and optics. Compared with bulk mesoporous titania materials, which are above a micrometer in size, nanometer-sized MTNs have additional properties, such as fast mass transport, strong adhesion to substrates and good dispersion in solution. However, it has generally been known that the successful synthesis of MTNs is very difficult owing to the rapid hydrolysis of titanium-containing precursors and the crystallization of titania upon thermal treatment. Finally, we review four emerging fields including photocatalysis, photovoltaic devices, sensing and biomedical applications of mesoporous titania materials. Because of its high surface area, controlled porous structure, suitable morphology and semiconducting behavior, mesoporous titania is expected to be used in innovative applications.

Impact Compaction of a Granular Material

NASA Astrophysics Data System (ADS)

Fenton, Gregg; Asay, Blaine; Todd, Steve; Grady, Dennis

2017-06-01

The dynamic behavior of granular materials has importance to a variety of engineering applications. Although, the mechanical behavior of granular materials have been studied extensively for several decades, the dynamic behavior of these materials remains poorly understood. High-quality experimental data are needed to improve our general understanding of granular material compaction physics. This paper describes how an instrumented plunger impact system can be used to measure the compaction process for granular materials at high and controlled strain rates and subsequently used for computational modelling. The experimental technique relies on a gas-gun driven plunger system to generate a compaction wave through a volume of granular material. This volume of material has been redundantly instrumented along the bed length to track the progression of the compaction wave, and the piston displacement is measured with Photon Doppler Velocimetry (PDV). Using the gathered experimental data along with the initial material tap density, a granular material equation of state can be determined.

The Tripartite Seminars at the Russian Methodological and Training Center: An Overview of Progress in Nuclear Materials Control and Accounting in the Russian Federation

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

Pshakin, Gennady; Dickman, Deborah A.; Ryazanov, Boris

2003-09-16

The development of the Russian Methodological and Training Center (RMTC) has been an important element of collaboration between the Russian Federation (RF), the European Union and the US. The RMTC, located at the Institute of Physics and Power Engineering (IPPE) in Obninsk, Russia has been designated by the Russian Ministry of Atomic Energy (Minatom) to provide nuclear materials protection, control and Accounting training to Minatom and the Federal Nuclear and Radiation Safety Authority (Gosatomnadzor) personnel. In addition, the RMTC was chartered with the responsibility of providing a venue for exchange of experiences and information between Russian and international specialists.

Progress in advanced high temperature materials technology

NASA Technical Reports Server (NTRS)

Freche, J. C.; Ault, G. M.

1976-01-01

Significant progress has recently been made in many high temperature material categories pertinent to such applications by the industrial community. These include metal matrix composites, superalloys, directionally solidified eutectics, coatings, and ceramics. Each of these material categories is reviewed and the current state-of-the-art identified, including some assessment, when appropriate, of progress, problems, and future directions.

Stereotactic Radiation Therapy can Safely and Durably Control Sites of Extra-Central Nervous System Oligoprogressive Disease in Anaplastic Lymphoma Kinase-Positive Lung Cancer Patients Receiving Crizotinib

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

Gan, Gregory N., E-mail: gregory.gan@ucdenver.edu; Weickhardt, Andrew J.; Scheier, Benjamin

Purpose: To analyze the durability and toxicity of radiotherapeutic local ablative therapy (LAT) applied to extra-central nervous system (eCNS) disease progression in anaplastic lymphoma kinase-positive non-small cell lung cancer (NSCLC) patients. Methods and Materials: Anaplastic lymphoma kinase-positive NSCLC patients receiving crizotinib and manifesting ≤4 discrete sites of eCNS progression were classified as having oligoprogressive disease (OPD). If subsequent progression met OPD criteria, additional courses of LAT were considered. Crizotinib was continued until eCNS progression was beyond OPD criteria or otherwise not suitable for further LAT. Results: Of 38 patients, 33 progressed while taking crizotinib. Of these, 14 had eCNS progressionmore » meeting OPD criteria suitable for radiotherapeutic LAT. Patients with eCNS OPD received 1-3 courses of LAT with radiation therapy. The 6- and 12-month actuarial local lesion control rates with radiation therapy were 100% and 86%, respectively. The 12-month local lesion control rate with single-fraction equivalent dose >25 Gy versus ≤25 Gy was 100% versus 60% (P=.01). No acute or late grade >2 radiation therapy-related toxicities were observed. Median overall time taking crizotinib among those treated with LAT versus those who progressed but were not suitable for LAT was 28 versus 10.1 months, respectively. Patients continuing to take crizotinib for >12 months versus ≤12 months had a 2-year overall survival rate of 72% versus 12%, respectively (P<.0001). Conclusions: Local ablative therapy safely and durably eradicated sites of individual lesion progression in anaplastic lymphoma kinase-positive NSCLC patients receiving crizotinib. A dose–response relationship for local lesion control was observed. The suppression of OPD by LAT in patients taking crizotinib allowed an extended duration of exposure to crizotinib, which was associated with longer overall survival.« less

Strain-Tuning Atomic Substitution in Two-Dimensional Atomic Crystals.

PubMed

Li, Honglai; Liu, Hongjun; Zhou, Linwei; Wu, Xueping; Pan, Yuhao; Ji, Wei; Zheng, Biyuan; Zhang, Qinglin; Zhuang, Xiujuan; Zhu, Xiaoli; Wang, Xiao; Duan, Xiangfeng; Pan, Anlian

2018-05-22

Atomic substitution offers an important route to achieve compositionally engineered two-dimensional nanostructures and their heterostructures. Despite the recent research progress, the fundamental understanding of the reaction mechanism has still remained unclear. Here, we reveal the atomic substitution mechanism of two-dimensional atomic layered materials. We found that the atomic substitution process depends on the varying lattice constant (strain) in monolayer crystals, dominated by two strain-tuning (self-promoted and self-limited) mechanisms using density functional theory calculations. These mechanisms were experimentally confirmed by the controllable realization of a graded substitution ratio in the monolayers by controlling the substitution temperature and time and further theoretically verified by kinetic Monte Carlo simulations. The strain-tuning atomic substitution processes are of general importance to other two-dimensional layered materials, which offers an interesting route for tailoring electronic and optical properties of these materials.

Hollow-structured mesoporous materials: chemical synthesis, functionalization and applications.

PubMed

Li, Yongsheng; Shi, Jianlin

2014-05-28

Hollow-structured mesoporous materials (HMMs), as a kind of mesoporous material with unique morphology, have been of great interest in the past decade because of the subtle combination of the hollow architecture with the mesoporous nanostructure. Benefitting from the merits of low density, large void space, large specific surface area, and, especially, the good biocompatibility, HMMs present promising application prospects in various fields, such as adsorption and storage, confined catalysis when catalytically active species are incorporated in the core and/or shell, controlled drug release, targeted drug delivery, and simultaneous diagnosis and therapy of cancers when the surface and/or core of the HMMs are functionalized with functional ligands and/or nanoparticles, and so on. In this review, recent progress in the design, synthesis, functionalization, and applications of hollow mesoporous materials are discussed. Two main synthetic strategies, soft-templating and hard-templating routes, are broadly sorted and described in detail. Progress in the main application aspects of HMMs, such as adsorption and storage, catalysis, and biomedicine, are also discussed in detail in this article, in terms of the unique features of the combined large void space in the core and the mesoporous network in the shell. Functionalization of the core and pore/outer surfaces with functional organic groups and/or nanoparticles, and their performance, are summarized in this article. Finally, an outlook of their prospects and challenges in terms of their controlled synthesis and scaled application is presented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Department of Defense Progress in Financial Management Reform

DTIC Science & Technology

2000-05-09

financial reporting , incomplete documentation, and weak internal controls, including computer controls, continue to prevent the government from accurately reporting a significant portion of its assets, liabilities, and costs. Material financial management deficiencies identified at DOD, taken together, continue to represent the single largest obstacle that must be effectively addressed to achieve an unqualified opinion on the U.S. government’s consolidated financial statements. DOD’s vast operations--with an estimated $1 trillion in assets, nearly $1

Radar cross section studies/compact range research

NASA Technical Reports Server (NTRS)

Burnside, W. D.; Dominek, A. K.; Gupta, I. J.; Newman, E. H.; Pathak, P. H.; Peters, L., Jr.

1989-01-01

Achievements in advancing the state-of-the-art in the measurement, control, and analysis of electromagnetic scattering from general aerodynamic targets are summarized. The major topics associated with this study include: (1) electromagnetic scattering analysis; (2) indoor scattering measurement systems; (3) RCS control; (4) waveform processing techniques; (5) material scattering and design studies; (6) design and evaluation of standard targets; and (7) antenna studies. Progress in each of these areas is reported and related publications are listed.

Cluster 1: commercializing additive manufacturing—hurdles in materials characterization and testing

DOE PAGES

Roach, R. A.; Gardner, S. H.

2017-10-20

A major challenge in the commercialization of additive manufactured (AM) materials and processes is the ability to achieve acceptance of processes and products. There has been some progress towards acceptance has been made by adapting legacy qualification paradigms to match with the very limited process control and monitoring offered by AM machines. The opportunity for in-situ measurement can provide process monitoring and control perhaps changing the way we qualify parts however it is limited by lack of adequate process measurement methods. New measurement techniques, sensors and correlations to relevant phenomena are needed that enable process control and monitoring for consistentlymore » producing high quality articles. Beyond process data we need to characterize uncertainties of performance in all aspects of material, process and final part. These are prerequisites to achieving articles that are indeed worthy of materials characterization efforts that establish a microstructural reference of desirable performance through process-structure-property relations. Only then can industry apply physics based understanding of the material, part and process to probabilistically predict performance of an AM part. Our paper provides a brief overview, discussion of hurdles and key areas where R&D investment is needed.« less

Cluster 1: commercializing additive manufacturing—hurdles in materials characterization and testing

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

Roach, R. A.; Gardner, S. H.

A major challenge in the commercialization of additive manufactured (AM) materials and processes is the ability to achieve acceptance of processes and products. There has been some progress towards acceptance has been made by adapting legacy qualification paradigms to match with the very limited process control and monitoring offered by AM machines. The opportunity for in-situ measurement can provide process monitoring and control perhaps changing the way we qualify parts however it is limited by lack of adequate process measurement methods. New measurement techniques, sensors and correlations to relevant phenomena are needed that enable process control and monitoring for consistentlymore » producing high quality articles. Beyond process data we need to characterize uncertainties of performance in all aspects of material, process and final part. These are prerequisites to achieving articles that are indeed worthy of materials characterization efforts that establish a microstructural reference of desirable performance through process-structure-property relations. Only then can industry apply physics based understanding of the material, part and process to probabilistically predict performance of an AM part. Our paper provides a brief overview, discussion of hurdles and key areas where R&D investment is needed.« less

Scanning electron microscopy of chronically implanted intracortical microelectrode arrays in non-human primates

NASA Astrophysics Data System (ADS)

Barrese, James C.; Aceros, Juan; Donoghue, John P.

2016-04-01

Objective. Signal attenuation is a major problem facing intracortical sensors for chronic neuroprosthetic applications. Many studies suggest that failure is due to gliosis around the electrode tips, however, mechanical and material causes of failure are often overlooked. The purpose of this study was to investigate the factors contributing to progressive signal decline by using scanning electron microscopy (SEM) to visualize structural changes in chronically implanted arrays and histology to examine the tissue response at corresponding implant sites. Approach. We examined eight chronically implanted intracortical microelectrode arrays (MEAs) explanted from non-human primates at times ranging from 37 to 1051 days post-implant. We used SEM, in vivo neural recordings, and histology (GFAP, Iba-1, NeuN). Three MEAs that were never implanted were also imaged as controls. Main results. SEM revealed progressive corrosion of the platinum electrode tips and changes to the underlying silicon. The parylene insulation was prone to cracking and delamination, and in some instances the silicone elastomer also delaminated from the edges of the MEA. Substantial tissue encapsulation was observed and was often seen growing into defects in the platinum and parylene. These material defects became more common as the time in vivo increased. Histology at 37 and 1051 days post-implant showed gliosis, disruption of normal cortical architecture with minimal neuronal loss, and high Iba-1 reactivity, especially within the arachnoid and dura. Electrode tracts were either absent or barely visible in the cortex at 1051 days, but were seen in the fibrotic encapsulation material suggesting that the MEAs were lifted out of the brain. Neural recordings showed a progressive drop in impedance, signal amplitude, and viable channels over time. Significance. These results provide evidence that signal loss in MEAs is truly multifactorial. Gliosis occurs in the first few months after implantation but does not prevent useful recordings for several years. Progressive meningeal fibrosis encapsulates and lifts MEAs out of the cortex while ongoing foreign body reactions lead to progressive degradation of the materials. Long-term impedance drops are due to the corrosion of platinum, cracking and delamination of parylene, and delamination of silicone elastomer. Oxygen radicals released by cells of the immune system likely mediate the degradation of these materials. Future MEA designs must address these problems through more durable insulation materials, more inert electrode alloys, and pharmacologic suppression of fibroblasts and leukocytes.

Scanning electron microscopy of chronically implanted intracortical microelectrode arrays in non-human primates

PubMed Central

Barrese, James C; Aceros, Juan; Donoghue, John P

2016-01-01

Objective Signal attenuation is a major problem facing intracortical sensors for chronic neuroprosthetic applications. Many studies suggest that failure is due to gliosis around the electrode tips, however, mechanical and material causes of failure are often overlooked. The purpose of this study was to investigate the factors contributing to progressive signal decline by using scanning electron microscopy (SEM) to visualize structural changes in chronically implanted arrays and histology to examine the tissue response at corresponding implant sites. Approach We examined eight chronically implanted intracortical microelectrode arrays (MEAs) explanted from non-human primates at times ranging from 37 to 1051 days post-implant. We used SEM, in vivo neural recordings, and histology (GFAP, Iba-1, NeuN). Three MEAs that were never implanted were also imaged as controls. Main results SEM revealed progressive corrosion of the platinum electrode tips and changes to the underlying silicon. The parylene insulation was prone to cracking and delamination, and in some instances the silicone elastomer also delaminated from the edges of the MEA. Substantial tissue encapsulation was observed and was often seen growing into defects in the platinum and parylene. These material defects became more common as the time in vivo increased. Histology at 37 and 1051 days post-implant showed gliosis, disruption of normal cortical architecture with minimal neuronal loss, and high Iba-1 reactivity, especially within the arachnoid and dura. Electrode tracts were either absent or barely visible in the cortex at 1051 days, but were seen in the fibrotic encapsulation material suggesting that the MEAs were lifted out of the brain. Neural recordings showed a progressive drop in impedance, signal amplitude, and viable channels over time. Significance These results provide evidence that signal loss in MEAs is truly multifactorial. Gliosis occurs in the first few months after implantation but does not prevent useful recordings for several years. Progressive meningeal fibrosis encapsulates and lifts MEAs out of the cortex while ongoing foreign body reactions lead to progressive degradation of the materials. Long-term impedance drops are due to the corrosion of platinum, cracking and delamination of parylene, and delamination of silicone elastomer. Oxygen radicals released by cells of the immune system likely mediate the degradation of these materials. Future MEA designs must address these problems through more durable insulation materials, more inert electrode alloys, and pharmacologic suppression of fibroblasts and leukocytes. PMID:26824680

Scanning electron microscopy of chronically implanted intracortical microelectrode arrays in non-human primates.

PubMed

Barrese, James C; Aceros, Juan; Donoghue, John P

2016-04-01

Signal attenuation is a major problem facing intracortical sensors for chronic neuroprosthetic applications. Many studies suggest that failure is due to gliosis around the electrode tips, however, mechanical and material causes of failure are often overlooked. The purpose of this study was to investigate the factors contributing to progressive signal decline by using scanning electron microscopy (SEM) to visualize structural changes in chronically implanted arrays and histology to examine the tissue response at corresponding implant sites. We examined eight chronically implanted intracortical microelectrode arrays (MEAs) explanted from non-human primates at times ranging from 37 to 1051 days post-implant. We used SEM, in vivo neural recordings, and histology (GFAP, Iba-1, NeuN). Three MEAs that were never implanted were also imaged as controls. SEM revealed progressive corrosion of the platinum electrode tips and changes to the underlying silicon. The parylene insulation was prone to cracking and delamination, and in some instances the silicone elastomer also delaminated from the edges of the MEA. Substantial tissue encapsulation was observed and was often seen growing into defects in the platinum and parylene. These material defects became more common as the time in vivo increased. Histology at 37 and 1051 days post-implant showed gliosis, disruption of normal cortical architecture with minimal neuronal loss, and high Iba-1 reactivity, especially within the arachnoid and dura. Electrode tracts were either absent or barely visible in the cortex at 1051 days, but were seen in the fibrotic encapsulation material suggesting that the MEAs were lifted out of the brain. Neural recordings showed a progressive drop in impedance, signal amplitude, and viable channels over time. These results provide evidence that signal loss in MEAs is truly multifactorial. Gliosis occurs in the first few months after implantation but does not prevent useful recordings for several years. Progressive meningeal fibrosis encapsulates and lifts MEAs out of the cortex while ongoing foreign body reactions lead to progressive degradation of the materials. Long-term impedance drops are due to the corrosion of platinum, cracking and delamination of parylene, and delamination of silicone elastomer. Oxygen radicals released by cells of the immune system likely mediate the degradation of these materials. Future MEA designs must address these problems through more durable insulation materials, more inert electrode alloys, and pharmacologic suppression of fibroblasts and leukocytes.

Ion beam sputter modification of the surface morphology of biological implants

NASA Technical Reports Server (NTRS)

Weigand, A. J.; Banks, B. A.

1976-01-01

The surface chemistry and texture of materials used for biological implants may significantly influence their performance and biocompatibility. Recent interest in the microscopic control of implant surface texture has led to the evaluation of ion beam sputtering as a potentially useful surface roughening technique. Ion sources, similar to electron bombardment ion thrusters designed for propulsive applications, are used to roughen the surfaces of various biocompatible alloys or polymer materials. These materials are typically used for dental implants, orthopedic prostheses, vascular prostheses, and artificial heart components. Masking techniques and resulting surface textures are described along with progress concerning evaluation of the biological response to the ion beam sputtered surfaces.

Ion-beam-sputter modification of the surface morphology of biological implants

NASA Technical Reports Server (NTRS)

Weigand, A. J.; Banks, B. A.

1977-01-01

The surface chemistry and texture of materials used for biological implants may significantly influence their performance and biocompatibility. Recent interest in the microscopic control of implant surface texture has led to the evaluation of ion-beam sputtering as a potentially useful surface roughening technique. Ion sources, similar to electron-bombardment ion thrusters designed for propulsive applications, are used to roughen the surfaces of various biocompatible alloys or polymer materials. These materials are typically used for dental implants, orthopedic prostheses, vascular prostheses, and artificial heart components. Masking techniques and resulting surface textures are described along with progress concerning evaluation of the biological response to the ion-beam-sputtered surfaces.

Human Factors in the Design of a Computer-Assisted Instruction System. Technical Progress Report.

ERIC Educational Resources Information Center

Mudge, J. C.

A research project built an author-controlled computer-assisted instruction (CAI) system to study ease-of-use factors in student-system, author-system, and programer-system interfaces. Interfaces were designed and observed in use and systematically revised. Development of course material by authors, use by students, and administrative tasks were…

Variability in Reading Ability Gains as a Function of Computer-Assisted Instruction Method of Presentation

ERIC Educational Resources Information Center

Johnson, Erin Phinney; Perry, Justin; Shamir, Haya

2010-01-01

This study examines the effects on early reading skills of three different methods of presenting material with computer-assisted instruction (CAI): (1) learner-controlled picture menu, which allows the student to choose activities, (2) linear sequencer, which progresses the students through lessons at a pre-specified pace, and (3) mastery-based…

Synthetic Fabrication of Nanoscale MoS2-Based Transition Metal Sulfides

PubMed Central

Wang, Shutao; An, Changhua; Yuan, Jikang

2010-01-01

Transition metal sulfides are scientifically and technologically important materials. This review summarizes recent progress on the synthetic fabrication of transition metal sulfides nanocrystals with controlled shape, size, and surface functionality. Special attention is paid to the case of MoS2 nanoparticles, where organic (surfactant, polymer), inorganic (support, promoter, doping) compounds and intercalation chemistry are applied.

Metal-Organic Frameworks for Separation.

PubMed

Zhao, Xiang; Wang, Yanxiang; Li, Dong-Sheng; Bu, Xianhui; Feng, Pingyun

2018-03-27

Separation is an important industrial step with critical roles in the chemical, petrochemical, pharmaceutical, and nuclear industries, as well as in many other fields. Although much progress has been made, the development of better separation technologies, especially through the discovery of high-performance separation materials, continues to attract increasing interest due to concerns over factors such as efficiency, health and environmental impacts, and the cost of existing methods. Metal-organic frameworks (MOFs), a rapidly expanding family of crystalline porous materials, have shown great promise to address various separation challenges due to their well-defined pore size and unprecedented tunability in both composition and pore geometry. In the past decade, extensive research is performed on applications of MOF materials, including separation and capture of many gases and vapors, and liquid-phase separation involving both liquid mixtures and solutions. MOFs also bring new opportunities in enantioselective separation and are amenable to morphological control such as fabrication of membranes for enhanced separation outcomes. Here, some of the latest progress in the applications of MOFs for several key separation issues, with emphasis on newly synthesized MOF materials and the impact of their compositional and structural features on separation properties, are reviewed and highlighted. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Point Defects in Oxides: Tailoring Materials Through Defect Engineering

NASA Astrophysics Data System (ADS)

Tuller, Harry L.; Bishop, Sean R.

2011-08-01

Optimization of electrical, optical, mechanical, and other properties of many advanced, functional materials today relies on precise control of point defects. This article illustrates the progress that has been made in elucidating the often complex equilibria exhibited by many materials by examining two recently well-characterized model systems, TlBr for radiation detection and PrxCe1-xO2-δ, of potential interest in solid-oxide fuel cells. The interplay between material composition, electrical conductivity, and mechanical properties (electrochemomechanics) is discussed, and implications in these relations, for example, enhancing electrical properties through large mechanical strains, are described. The impact of space charge and strain fields at interfaces, particularly important in nanostructure materials, is also emphasized. Key experimental techniques useful in characterizing bulk and surface defects are summarized and reviewed.

Low-temperature magnetotransport in Si/SiGe heterostructures on 300 mm Si wafers

NASA Astrophysics Data System (ADS)

Scappucci, Giordano; Yeoh, L.; Sabbagh, D.; Sammak, A.; Boter, J.; Droulers, G.; Kalhor, N.; Brousse, D.; Veldhorst, M.; Vandersypen, L. M. K.; Thomas, N.; Roberts, J.; Pillarisetty, R.; Amin, P.; George, H. C.; Singh, K. J.; Clarke, J. S.

Undoped Si/SiGe heterostructures are a promising material stack for the development of spin qubits in silicon. To deploy a qubit into high volume manufacturing in a quantum computer requires stringent control over substrate uniformity and quality. Electron mobility and valley splitting are two key electrical metrics of substrate quality relevant for qubits. Here we present low-temperature magnetotransport measurements of strained Si quantum wells with mobilities in excess of 100000 cm2/Vs fabricated on 300 mm wafers within the framework of advanced semiconductor manufacturing. These results are benchmarked against the results obtained in Si quantum wells deposited on 100 mm Si wafers in an academic research environment. To ensure rapid progress in quantum wells quality we have implemented fast feedback loops from materials growth, to heterostructure FET fabrication, and low temperature characterisation. On this topic we will present recent progress in developing a cryogenic platform for high-throughput magnetotransport measurements.

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

Truong, Minh Tam, E-mail: mitruong@bu.edu; Kachnic, Lisa A.; Grillone, Gregory A.

Purpose: To evaluate the efficacy of conformal external beam radiotherapy (RT) for local control of progressive airway amyloidosis. Methods and Materials: We conducted a retrospective review of patients with biopsy-proven progressive airway amyloidosis treated with conformal RT between 2000 and 2006 at Boston Medical Center. The patients were evaluated for performance status and pulmonary function, with computed tomography and endoscopy after RT compared with the pretreatment studies. Local control was defined as the lack of progression of airway wall thickening on computed tomography imaging and stable endobronchial deposits by endoscopy. Results: A total of 10 symptomatic airway amyloidosis patients (3more » laryngeal and 7 tracheobronchial) received RT to a median total dose of 20 Gy in 10 fractions within 2 weeks. At a median follow-up of 6.7 years (range, 1.5-10.3), 8 of the 10 patients had local control. The remaining 2 patients underwent repeat RT 6 and 8.4 months after initial RT, 1 for persistent bronchial obstruction and 1 for progression of subglottic amyloid disease with subsequent disease control. The Eastern Cooperative Oncology Group performance status improved at a median of 18 months after RT compared with the baseline values, from a median score of 2 to a median of 1 (p = .035). Airflow (forced expiratory volume in 1 second) measurements increased compared with the baseline values at each follow-up evaluation, reaching a 10.7% increase (p = .087) at the last testing (median duration, 64.8 months). Acute toxicity was limited to Grade 1-2 esophagitis, occurring in 40% of patients. No late toxicity was observed. Conclusions: RT prevented progressive amyloid deposition in 8 of 10 patients, resulting in a marginally increased forced expiratory volume in 1 second, and improved functional capacity, without late morbidity.« less

Modeling Freedom From Progression for Standard-Risk Medulloblastoma: A Mathematical Tumor Control Model With Multiple Modes of Failure

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

Brodin, N. Patrik, E-mail: nils.patrik.brodin@rh.dk; Niels Bohr Institute, University of Copenhagen, Copenhagen; Vogelius, Ivan R.

2013-10-01

Purpose: As pediatric medulloblastoma (MB) is a relatively rare disease, it is important to extract the maximum information from trials and cohort studies. Here, a framework was developed for modeling tumor control with multiple modes of failure and time-to-progression for standard-risk MB, using published pattern of failure data. Methods and Materials: Outcome data for standard-risk MB published after 1990 with pattern of relapse information were used to fit a tumor control dose-response model addressing failures in both the high-dose boost volume and the elective craniospinal volume. Estimates of 5-year event-free survival from 2 large randomized MB trials were used tomore » model the time-to-progression distribution. Uncertainty in freedom from progression (FFP) was estimated by Monte Carlo sampling over the statistical uncertainty in input data. Results: The estimated 5-year FFP (95% confidence intervals [CI]) for craniospinal doses of 15, 18, 24, and 36 Gy while maintaining 54 Gy to the posterior fossa was 77% (95% CI, 70%-81%), 78% (95% CI, 73%-81%), 79% (95% CI, 76%-82%), and 80% (95% CI, 77%-84%) respectively. The uncertainty in FFP was considerably larger for craniospinal doses below 18 Gy, reflecting the lack of data in the lower dose range. Conclusions: Estimates of tumor control and time-to-progression for standard-risk MB provides a data-driven setting for hypothesis generation or power calculations for prospective trials, taking the uncertainties into account. The presented methods can also be applied to incorporate further risk-stratification for example based on molecular biomarkers, when the necessary data become available.« less

Recent progress on biodegradable materials and transient electronics.

PubMed

Li, Rongfeng; Wang, Liu; Kong, Deying; Yin, Lan

2018-09-01

Transient electronics (or biodegradable electronics) is an emerging technology whose key characteristic is an ability to dissolve, resorb, or physically disappear in physiological environments in a controlled manner. Potential applications include eco-friendly sensors, temporary biomedical implants, and data-secure hardware. Biodegradable electronics built with water-soluble, biocompatible active and passive materials can provide multifunctional operations for diagnostic and therapeutic purposes, such as monitoring intracranial pressure, identifying neural networks, assisting wound healing process, etc. This review summarizes the up-to-date materials strategies, manufacturing schemes, and device layouts for biodegradable electronics, and the outlook is discussed at the end. It is expected that the translation of these materials and technologies into clinical settings could potentially provide vital tools that are beneficial for human healthcare.

Remote Sensor Application Studies Progress Report, July L, 1968 to June 30, 1969. Controlled Field Experiments

USGS Publications Warehouse

Rowan, L.C.; Offield, T.W.; Watson, R.D.; Cannon, P.J.; Grolier, H.J.; Pohn, H.A.; Watson, Kenneth

1970-01-01

Field Sites have been selected for controlled experiments to analyze physical and chemical parameters affecting the response of electromagnetic radiation to geological materials. Considerations in the selection of the sites are the availability of good exposures of nearly monomineralic rocks, level of geologic understanding, and ease of access. Seven sites, where work is underway or planned, contain extensive outcrops of the following rocks: stanstone, limestone, dolomite, and gypsum. Field measurement of quartz have been conducted at four sites.

Spacelab

NASA Image and Video Library

1992-01-01

This photograph shows activities during the International Microgravity Laboratory-1 (IML-1) mission (STS-42) in the Payload Operations Control Center (POCC) at the Marshall Space Flight Center. Members of the Fluid Experiment System (FES) group monitor the progress of their experiment through video at the POCC. The IML-1 mission was the first in a series of Shuttle flights dedicated to fundamental materials and life sciences research. The mission was to explore, in depth, the complex effects of weightlessness on living organisms and materials processing. The crew conducted experiments on the human nervous system's adaptation to low gravity and the effects on other life forms such as shrimp eggs, lentil seedlings, fruit fly eggs, and bacteria. Low gravity materials processing experiments included crystal growth from a variety of substances such as enzymes, mercury, iodine, and virus. The International space science research organizations that participated in this mission were: The U.S. National Aeronautics and Space Administion, the European Space Agency, the Canadian Space Agency, the French National Center for Space Studies, the German Space Agency, and the National Space Development Agency of Japan. The POCC was the air/ground communication charnel used between astronauts aboard the Spacelab and scientists, researchers, and ground control teams during the Spacelab missions. The facility made instantaneous video and audio communications possible for scientists on the ground to follow the progress and to send direct commands of their research almost as if they were in space with the crew.

Materials discovery at high pressures

NASA Astrophysics Data System (ADS)

Zhang, Lijun; Wang, Yanchao; Lv, Jian; Ma, Yanming

2017-02-01

Pressure is a fundamental thermodynamic variable that can be used to control the properties of materials, because it reduces interatomic distances and profoundly modifies electronic orbitals and bonding patterns. It is thus a versatile tool for the creation of exotic materials not accessible at ambient conditions. Recently developed static and dynamic high-pressure experimental techniques have led to the synthesis of many functional materials with excellent performance: for example, superconductors, superhard materials and high-energy-density materials. Some of these advances have been aided and accelerated by first-principles crystal-structure searching simulations. In this Review, we discuss recent progress in high-pressure materials discovery, placing particular emphasis on the record high-temperature superconductivity in hydrogen sulfide and on nanotwinned cubic boron nitride and diamond, the hardest known materials. Energy materials and exotic chemical materials obtained under high pressures are also discussed. The main drawback of high-pressure materials is their destabilization after pressure release; this problem and its possible solutions are surveyed in the conclusions, which also provide an outlook on the future developments in the field.

Progressive Damage and Fracture in Composites Under Dynamic Loading

NASA Technical Reports Server (NTRS)

Minnetyan, Levon

1994-01-01

A computational simulation tool is used to evaluate the various stages of damage progression in composite materials during losipescu shear testing. Unidirectional composite specimens with either the major or minor material axis in the load direction are considered. Damage progression characteristics are described for each specimen using two types of boundary conditions. A procedure is outlined regarding the use of computational simulation in the testing of composite materials.

Engineering artificial machines from designable DNA materials for biomedical applications.

PubMed

Qi, Hao; Huang, Guoyou; Han, Yulong; Zhang, Xiaohui; Li, Yuhui; Pingguan-Murphy, Belinda; Lu, Tian Jian; Xu, Feng; Wang, Lin

2015-06-01

Deoxyribonucleic acid (DNA) emerges as building bricks for the fabrication of nanostructure with complete artificial architecture and geometry. The amazing ability of DNA in building two- and three-dimensional structures raises the possibility of developing smart nanomachines with versatile controllability for various applications. Here, we overviewed the recent progresses in engineering DNA machines for specific bioengineering and biomedical applications.

Altitude valve for railway suspension control system

NASA Astrophysics Data System (ADS)

Zhang, Xuan; Zhang, Lihao; Li, Qingxuan; Chen, WanSong

2017-09-01

With the variation of people and material during vehicle service, the gravity of vehicle could be unbalanced. As a result it might cause accident. In order to solve this problem, altitude valve is assembled on board. It can adjust the gravity of vehicle by the intake and outlet progress of the spring in the altitude valve to prevent the tilt of vehicles.

Engineering Artificial Machines from Designable DNA Materials for Biomedical Applications

PubMed Central

Huang, Guoyou; Han, Yulong; Zhang, Xiaohui; Li, Yuhui; Pingguan-Murphy, Belinda; Lu, Tian Jian; Xu, Feng

2015-01-01

Deoxyribonucleic acid (DNA) emerges as building bricks for the fabrication of nanostructure with complete artificial architecture and geometry. The amazing ability of DNA in building two- and three-dimensional structures raises the possibility of developing smart nanomachines with versatile controllability for various applications. Here, we overviewed the recent progresses in engineering DNA machines for specific bioengineering and biomedical applications. PMID:25547514

Advances in photonic MOEMS-MEMS device thinning and polishing

NASA Astrophysics Data System (ADS)

McAneny, James J.; Kennedy, Mark; McGroggan, Tom

2010-02-01

As devices continue to increase in density and complexity, ever more stringent specifications are placed on the wafer scale equipment manufacturers to produce higher quality and higher output. This results in greater investment and more resource being diverted into producing tools and processes which can meet the latest demanding criteria. Substrate materials employed in the fabrication process range from Silicon through InP and include GaAs, InSb and other optical networking or waveguide materials. With this diversity of substrate materials presented, controlling the geometries and surfaces grows progressively more challenging. This article highlights the key parameters which require close monitoring and control in order to produce highly precise wafers as part of the fabrication process. Several as cut and commercially available standard polished wafer materials were used in empirical trials to test tooling options in generating high levels of geometric control over the dimensions while producing high quality surface finishes. Specific attention was given to the measurement and control of: flatness; parallelism/TTV; surface roughness and final target thickness as common specifications required by the industry. By combining the process variables of: plate speed, download pressure, slurry flow rate and concentration, pad type and wafer travel path across the polish pad, the effect of altering these variables was recorded and analysed to realize the optimum process conditions for the materials under test. The results being then used to design improved methods and tooling for the thinning and polishing of photonic materials applied to MOEMS-MEMS device fabrication.

Magnetization manipulation in multiferroic devices.

NASA Astrophysics Data System (ADS)

Gajek, Martin; Martin, Lane; Hao Chu, Ying; Huijben, Mark; Barry, Micky; Ramesh, Ramamoorthy

2008-03-01

Controlling magnetization by purely electrical means is a a central topic in spintronics. A very recent route towards this goal is to exploit the coupling between multiple ferroic orders which coexist in multiferroic materials. BiFeO3 (BFO) displays antiferromagnetic and ferroelectric orderings at room temperature and can thus be used as an electrically controllable pinning layer for a ferromagnetic electrode. Furthermore BFO remains ferroelectric down to 2nm and can therefore be integrated as a tunnel barrier in MTJ's. We will describe these two architecture schemes and report on our progresses towards the control of magnetization via the multiferroic layer in those structures.

An advanced teaching scheme for integrating problem-based learning in control education

NASA Astrophysics Data System (ADS)

Juuso, Esko K.

2018-03-01

Engineering education needs to provide both theoretical knowledge and problem-solving skills. Many topics can be presented in lectures and computer exercises are good tools in teaching the skills. Learning by doing is combined with lectures to provide additional material and perspectives. The teaching scheme includes lectures, computer exercises, case studies, seminars and reports organized as a problem-based learning process. In the gradually refining learning material, each teaching method has its own role. The scheme, which has been used in teaching two 4th year courses, is beneficial for overall learning progress, especially in bilingual courses. The students become familiar with new perspectives and are ready to use the course material in application projects.

Ceramic Technology for Advanced Heat Engines Project. Semiannual progress report, October 1984-March 1985

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

Not Available

1985-09-01

A five-year project plan was developed with extensive input from private industry. The objective of the project is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applicationsmore » in these engines.« less

Ceramic technology for advanced heat engines project: Semiannual progress report for April through September 1986

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

Not Available

1987-03-01

An assessment of needs was completed, and a five-year project plan was developed with extensive input from private industry. Objective is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barriermore » and wear applications in these engines.« less

Approaches for Achieving Superlubricity in Two-Dimensional Materials.

PubMed

Berman, Diana; Erdemir, Ali; Sumant, Anirudha V

2018-03-27

Controlling friction and reducing wear of moving mechanical systems is important in many applications, from nanoscale electromechanical systems to large-scale car engines and wind turbines. Accordingly, multiple efforts are dedicated to design materials and surfaces for efficient friction and wear manipulation. Recent advances in two-dimensional (2D) materials, such as graphene, hexagonal boron nitride, molybdenum disulfide, and other 2D materials opened an era for conformal, atomically thin solid lubricants. However, the process of effectively incorporating 2D films requires a fundamental understanding of the atomistic origins of friction. In this review, we outline basic mechanisms for frictional energy dissipation during sliding of two surfaces against each other, and the procedures for manipulating friction and wear by introducing 2D materials at the tribological interface. Finally, we highlight recent progress in implementing 2D materials for friction reduction to near-zero values-superlubricity-across scales from nano- up to macroscale contacts.

Controlled synthesis of titania using water-soluble titanium complexes: A review

NASA Astrophysics Data System (ADS)

Truong, Quang Duc; Dien, Luong Xuan; Vo, Dai-Viet N.; Le, Thanh Son

2017-07-01

The development of human society has led to the increase in energy and resources consumption as well as the arising problems of environmental damage and the toxicity to the human health. The development of novel synthesis method which tolerates utilization of toxic solvents and chemicals would fulfill the demand of the society for safer, softer, and environmental friendly technologies. For the past decades, a remarkable progress has been attained in the development of new water-soluble titanium complexes (WSTC) and their use for the synthesis of nanocrystalline titanium dioxide materials by aqueous solution-based approaches. The progress of synthesis of nanocrystalline titanium dioxide using such WSTCs is reviewed in this work. The key structural features responsible for the successfully controlled synthesis of TiO2 are discussed to provide guidelines for the morphology-controlled synthesis. Finally, this review ends with a summary and some perspectives on the challenges as well as new directions in this fascinating research.

Organic-inorganic hybrid lead halide perovskites for optoelectronic and electronic applications.

PubMed

Zhao, Yixin; Zhu, Kai

2016-02-07

Organic and inorganic hybrid perovskites (e.g., CH(3)NH(3)PbI(3)), with advantages of facile processing, tunable bandgaps, and superior charge-transfer properties, have emerged as a new class of revolutionary optoelectronic semiconductors promising for various applications. Perovskite solar cells constructed with a variety of configurations have demonstrated unprecedented progress in efficiency, reaching about 20% from multiple groups after only several years of active research. A key to this success is the development of various solution-synthesis and film-deposition techniques for controlling the morphology and composition of hybrid perovskites. The rapid progress in material synthesis and device fabrication has also promoted the development of other optoelectronic applications including light-emitting diodes, photodetectors, and transistors. Both experimental and theoretical investigations on organic-inorganic hybrid perovskites have enabled some critical fundamental understandings of this material system. Recent studies have also demonstrated progress in addressing the potential stability issue, which has been identified as a main challenge for future research on halide perovskites. Here, we review recent progress on hybrid perovskites including basic chemical and crystal structures, chemical synthesis of bulk/nanocrystals and thin films with their chemical and physical properties, device configurations, operation principles for various optoelectronic applications (with a focus on solar cells), and photophysics of charge-carrier dynamics. We also discuss the importance of further understanding of the fundamental properties of hybrid perovskites, especially those related to chemical and structural stabilities.

Rare earth fluoride nano-/microstructures: hydrothermal synthesis, luminescent properties and applications.

PubMed

Zhao, Qian; Xu, Zhenhe; Sun, Yaguang

2014-02-01

Rare earth fluoride materials have attracted wide interest and come to the forefront in nanophotonics due to their distinct electrical, optical and magnetic properties as well as their potential applications in diverse fields such as optical telecommunication, lasers, biochemical probes, infrared quantum counters, and medical diagnostics. This review presents a comprehensive overview of the flourishing field of rare earth fluorides materials in the past decade. We summarize the recent research progress on the preparation, morphology, luminescent properties and application of rare earth fluoride-based luminescent materials by hydrothermal systems. Various rare earth fluoride materials are obtained by fine-tuning of experimental conditions, such as capping agents, fluoride source, acidity, temperature and reaction time. The controlled morphology, luminescent properties and application of the rare earth fluorides are briefly discussed with typical examples.

Biosafe Nanoscale Pharmaceutical Adjuvant Materials

PubMed Central

Jin, Shubin; Li, Shengliang; Wang, Chongxi; Liu, Juan; Yang, Xiaolong; Wang, Paul C.; Zhang, Xin; Liang, Xing-Jie

2014-01-01

Thanks to developments in the field of nanotechnology over the past decades, more and more biosafe nanoscale materials have become available for use as pharmaceutical adjuvants in medical research. Nanomaterials possess unique properties which could be employed to develop drug carriers with longer circulation time, higher loading capacity, better stability in physiological conditions, controlled drug release, and targeted drug delivery. In this review article, we will review recent progress in the application of representative organic, inorganic and hybrid biosafe nanoscale materials in pharmaceutical research, especially focusing on nanomaterial-based novel drug delivery systems. In addition, we briefly discuss the advantages and notable functions that make these nanomaterials suitable for the design of new medicines; the biosafety of each material discussed in this article is also highlighted to provide a comprehensive understanding of their adjuvant attributes. PMID:25429253

Progressive damage and rupture in polymers

NASA Astrophysics Data System (ADS)

Talamini, Brandon; Mao, Yunwei; Anand, Lallit

2018-02-01

Progressive damage, which eventually leads to failure, is ubiquitous in biological and synthetic polymers. The simplest case to consider is that of elastomeric materials which can undergo large reversible deformations with negligible rate dependence. In this paper we develop a theory for modeling progressive damage and rupture of such materials. We extend the phase-field method, which is widely used to describe the damage and fracture of brittle materials, to elastomeric materials undergoing large deformations. A central feature of our theory is the recognition that the free energy of elastomers is not entirely entropic in nature - there is also an energetic contribution from the deformation of the bonds in the chains. It is the energetic part in the free energy which is the driving force for progressive damage and fracture.

Review of progress in quantitative NDE

NASA Astrophysics Data System (ADS)

s of 386 papers and plenary presentations are included. The plenary sessions are related to the national technology initiative. The other sessions covered the following NDE topics: corrosion, electromagnetic arrays, elastic wave scattering and backscattering/noise, civil structures, material properties, holography, shearography, UT wave propagation, eddy currents, coatings, signal processing, radiography, computed tomography, EM imaging, adhesive bonds, NMR, laser ultrasonics, composites, thermal techniques, magnetic measurements, nonlinear acoustics, interface modeling and characterization, UT transducers, new techniques, joined materials, probes and systems, fatigue cracks and fracture, imaging and sizing, NDE in engineering and process control, acoustics of cracks, and sensors. An author index is included.

[Medical application of nano-materials].

PubMed

Jiang, Hui-qing; Chen, Yi-fei

2002-11-01

To review the research progress and medical application of nano-materials. The literature review and comprehensive analysis, methods were used in this study. The Nanotechnology is a typical crossing knowledge. It could be extensively applied in the fields of novel biomaterials, effective transmission of bioactive factor; the detection of functions for all vital organ systems, vascular circulation condition, the control of repair of burn trauma wounds will be monitored by the varied methods of nano technology combined with molecular biological engineering. The application of Nanotechnology will play important roles in clinical medicine, wound repair and basic research for the traditional Chinese medicine.

Potential of Electrospun Nanofibers for Biomedical and Dental Applications

PubMed Central

Zafar, Muhammad; Najeeb, Shariq; Khurshid, Zohaib; Vazirzadeh, Masoud; Zohaib, Sana; Najeeb, Bilal; Sefat, Farshid

2016-01-01

Electrospinning is a versatile technique that has gained popularity for various biomedical applications in recent years. Electrospinning is being used for fabricating nanofibers for various biomedical and dental applications such as tooth regeneration, wound healing and prevention of dental caries. Electrospun materials have the benefits of unique properties for instance, high surface area to volume ratio, enhanced cellular interactions, protein absorption to facilitate binding sites for cell receptors. Extensive research has been conducted to explore the potential of electrospun nanofibers for repair and regeneration of various dental and oral tissues including dental pulp, dentin, periodontal tissues, oral mucosa and skeletal tissues. However, there are a few limitations of electrospinning hindering the progress of these materials to practical or clinical applications. In terms of biomaterials aspects, the better understanding of controlled fabrication, properties and functioning of electrospun materials is required to overcome the limitations. More in vivo studies are definitely required to evaluate the biocompatibility of electrospun scaffolds. Furthermore, mechanical properties of such scaffolds should be enhanced so that they resist mechanical stresses during tissue regeneration applications. The objective of this article is to review the current progress of electrospun nanofibers for biomedical and dental applications. In addition, various aspects of electrospun materials in relation to potential dental applications have been discussed. PMID:28787871

Developing Exemplar Interactive Multimedia Instruction for Unmanned Aircraft System Repairers

DTIC Science & Technology

2017-08-01

material and also compared the effectiveness of two different IMI design approaches used to progress the learner through the various training modules...instruction. For the Hydraulics Theory and Components, we compared the learner-controlled Interactive Multimedia Instruction and the designer ... Design Three UAS Repairer IMI modules were developed, and the effectiveness of each was compared to the current live instruction covering the

Sandia 25-meter compressed helium/air gun

NASA Astrophysics Data System (ADS)

Setchell, R. E.

1982-04-01

For nearly twenty years the Sandia 25-meter compressed gas gun has been an important tool for studying condensed materials subjected to transient shock compression. Major system modifications are now in progress to provide new control, instrumentation, and data acquisition capabilities. These features will ensure that the facility can continue as an effective means of investigating a variety of physical and chemical processes in shock-compressed solids.

Natural Models for Autonomous Control of Spatial Navigation, Sensing, and Guidance

DTIC Science & Technology

2013-05-28

the opsins of deep-sea fishes , including their ability to withstand pressure, a significant study of how sensing proteins function in difficult...polarization sensing, we will gain insight concerning functional differences among materials which could have application for fabrication or design...have made excellent progress towards understanding how polarized-light receptors in animals function as well, including their function at the

FY2016 Lightweight Materials Annual Progress Report

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

None, None

The Lightweight Materials research and development (R&D) area within the DOE Vehicle Technologies Office (VTO) provides support and guidance for many cutting-edge automotive technologies under development. Research focuses on addressing critical barriers to commercializing lightweight materials for passenger and commercial vehicles. This report describes the progress made on the research and development projects funded by the Lightweight Materials area.

Chitosan nanoparticle based delivery systems for sustainable agriculture.

PubMed

Kashyap, Prem Lal; Xiang, Xu; Heiden, Patricia

2015-01-01

Development of technologies that improve food productivity without any adverse impact on the ecosystem is the need of hour. In this context, development of controlled delivery systems for slow and sustained release of agrochemicals or genetic materials is crucial. Chitosan has emerged as a valuable carrier for controlled delivery of agrochemicals and genetic materials because of its proven biocompatibility, biodegradability, non-toxicity, and adsorption abilities. The major advantages of encapsulating agrochemicals and genetic material in a chitosan matrix include its ability to function as a protective reservoir for the active ingredients, protecting the ingredients from the surrounding environment while they are in the chitosan domain, and then controlling their release, allowing them to serve as efficient gene delivery systems for plant transformation or controlled release of pesticides. Despite the great progress in the use of chitosan in the area of medical and pharmaceutical sciences, there is still a wide knowledge gap regarding the potential application of chitosan for encapsulation of active ingredients in agriculture. Hence, the present article describes the current status of chitosan nanoparticle-based delivery systems in agriculture, and to highlight challenges that need to be overcome. Copyright © 2015 Elsevier B.V. All rights reserved.

Sound and heat revolutions in phononics

NASA Astrophysics Data System (ADS)

Maldovan, Martin

2013-11-01

The phonon is the physical particle representing mechanical vibration and is responsible for the transmission of everyday sound and heat. Understanding and controlling the phononic properties of materials provides opportunities to thermally insulate buildings, reduce environmental noise, transform waste heat into electricity and develop earthquake protection. Here I review recent progress and the development of new ideas and devices that make use of phononic properties to control both sound and heat. Advances in sonic and thermal diodes, optomechanical crystals, acoustic and thermal cloaking, hypersonic phononic crystals, thermoelectrics, and thermocrystals herald the next technological revolution in phononics.

Progress in the development and integration of fluid flow control tools in paper microfluidics.

PubMed

Fu, Elain; Downs, Corey

2017-02-14

Paper microfluidics is a rapidly growing subfield of microfluidics in which paper-like porous materials are used to create analytical devices. There is a need for higher performance field-use tests for many application domains including human disease diagnosis, environmental monitoring, and veterinary medicine. A key factor in creating high performance paper-based devices is the ability to manipulate fluid flow within the devices. This critical review is focused on the progress that has been made in (i) the development of fluid flow control tools and (ii) the integration of those tools into paper microfluidic devices. Further, we strive to be comprehensive in our presentation and provide historical context through discussion and performance comparisons, when possible, of both relevant earlier work and recent work. Finally, we discuss the major areas of focus for fluid flow methods development to advance the potential of paper microfluidics for high-performance field applications.

Recent Developments on Autonomous Corrosion Protection Through Encapsulation

NASA Technical Reports Server (NTRS)

Li, W.; Buhrow, J. W.; Calle, L. M.; Gillis, M.; Blanton, M.; Hanna, J.; Rawlins, J.

2015-01-01

This paper concerns recent progress in the development of a multifunctional smart coating, based on microencapsulation, for the autonomous detection and control of corrosion. Microencapsulation has been validated and optimized to incorporate desired corrosion control functionalities, such as early corrosion detection and inhibition, through corrosion-initiated release of corrosion indicators and inhibitors, as well as self-healing agent release triggered by mechanical damage. While proof-of-concept results have been previously reported, more recent research and development efforts have concentrated on improving coating compatibility and synthesis procedure scalability, with a targeted goal of obtaining easily dispersible pigment-grade type microencapsulated materials. The recent progress has resulted in the development of pH-sensitive microparticles as a corrosion-triggered delivery system for corrosion indicators and inhibitors. The synthesis and early corrosion indication results obtained with coating formulations that incorporate these microparticles are reported. The early corrosion indicating results were obtained with color changing and with fluorescent indicators.

User-defined Material Model for Thermo-mechanical Progressive Failure Analysis

NASA Technical Reports Server (NTRS)

Knight, Norman F., Jr.

2008-01-01

Previously a user-defined material model for orthotropic bimodulus materials was developed for linear and nonlinear stress analysis of composite structures using either shell or solid finite elements within a nonlinear finite element analysis tool. Extensions of this user-defined material model to thermo-mechanical progressive failure analysis are described, and the required input data are documented. The extensions include providing for temperature-dependent material properties, archival of the elastic strains, and a thermal strain calculation for materials exhibiting a stress-free temperature.

The status, recent progress and promise of superconducting materials for practical applications

NASA Astrophysics Data System (ADS)

Rowell, J. M.

1989-03-01

The author summarizes the progress in materials science and engineering that created today's superconducting technology. He reviews the state of the technology with conventional materials by looking at two particular applications: large-scale applications involving conductors, for example, magnets; and electronics and instrumentation applications. The state-of-the art is contrasted with the present understanding of the high-Tc oxide materials.

Recent progress in hollow sphere-based electrodes for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Zhao, Yan; Chen, Min; Wu, Limin

2016-08-01

Hollow spheres have drawn much attention in the area of energy storage and conversion, especially in high-performance supercapacitors owing to their well-defined morphologies, uniform size, low density and large surface area. And quite some significant breakthroughs have been made in advanced supercapacitor electrode materials with hollow sphere structures. In this review, we summarize and discuss the synthesis and application of hollow spheres with controllable structure and morphology as electrode materials for supercapacitors. First, we briefly introduce the fabrication strategies of hollow spheres for electrode materials. Then, we discuss in detail the recent advances in various hollow sphere-based electrode materials for supercapacitors, including single-shelled, yolk-shelled, urchin-like, double-shelled, multi-shelled, and mesoporous hollow structure-based symmetric and asymmetric supercapacitor devices. We conclude this review with some perspectives on the future research and development of the hollow sphere-based electrode materials.

Recent progress in hollow sphere-based electrodes for high-performance supercapacitors.

PubMed

Zhao, Yan; Chen, Min; Wu, Limin

2016-08-26

Hollow spheres have drawn much attention in the area of energy storage and conversion, especially in high-performance supercapacitors owing to their well-defined morphologies, uniform size, low density and large surface area. And quite some significant breakthroughs have been made in advanced supercapacitor electrode materials with hollow sphere structures. In this review, we summarize and discuss the synthesis and application of hollow spheres with controllable structure and morphology as electrode materials for supercapacitors. First, we briefly introduce the fabrication strategies of hollow spheres for electrode materials. Then, we discuss in detail the recent advances in various hollow sphere-based electrode materials for supercapacitors, including single-shelled, yolk-shelled, urchin-like, double-shelled, multi-shelled, and mesoporous hollow structure-based symmetric and asymmetric supercapacitor devices. We conclude this review with some perspectives on the future research and development of the hollow sphere-based electrode materials.

Materials and processing science: Limits for microelectronics

NASA Astrophysics Data System (ADS)

Rosenberg, R.

1988-09-01

The theme of this talk will be to illustrate examples of technologies that will drive materials and processing sciences to the limit and to describe some of the research being pursued to understand materials interactions which are pervasive to projected structure fabrication. It is to be expected that the future will see a progression to nanostructures where scaling laws will be tested and quantum transport will become more in evidence, to low temperature operation for tighter control and improved performance, to complex vertical profiles where 3D stacking and superlattices will produce denser packing and device flexibility, to faster communication links with optoelectronics, and to compatible packaging technologies. New low temperature processing techniques, such as epitaxy of silicon, PECVD of dielectrics, low temperature high pressure oxidation, silicon-germanium heterostructures, etc., must be combined with shallow metallurgies, new lithographic technologies, maskless patterning, rapid thermal processing (RTP) to produce needed profile control, reduce process incompatibilities and develop new device geometries. Materials interactions are of special consequence for chip substrates and illustrations of work in metal-ceramic and metal-polymer adhesion will be offered.

In situ thermomechanical testing methods for micro/nano-scale materials.

PubMed

Kang, Wonmo; Merrill, Marriner; Wheeler, Jeffrey M

2017-02-23

The advance of micro/nanotechnology in energy-harvesting, micropower, electronic devices, and transducers for automobile and aerospace applications has led to the need for accurate thermomechanical characterization of micro/nano-scale materials to ensure their reliability and performance. This persistent need has driven various efforts to develop innovative experimental techniques that overcome the critical challenges associated with precise mechanical and thermal control of micro/nano-scale specimens during material characterization. Here we review recent progress in the development of thermomechanical testing methods from miniaturized versions of conventional macroscopic test systems to the current state of the art of in situ uniaxial testing capabilities in electron microscopes utilizing either indentation-based microcompression or integrated microsystems. We discuss the major advantages/disadvantages of these methods with respect to specimen size, range of temperature control, ease of experimentation and resolution of the measurements. We also identify key challenges in each method. Finally, we summarize some of the important discoveries that have been made using in situ thermomechanical testing and the exciting research opportunities still to come in micro/nano-scale materials.

Progress Towards Highly Efficient Windows for Zero—Energy Buildings

NASA Astrophysics Data System (ADS)

Selkowitz, Stephen

2008-09-01

Energy efficient windows could save 4 quads/year, with an additional 1 quad/year gain from daylighting in commercial buildings. This corresponds to 13% of energy used by US buildings and 5% of all energy used by the US. The technical potential is thus very large and the economic potential is slowly becoming a reality. This paper describes the progress in energy efficient windows that employ low-emissivity glazing, electrochromic switchable coatings and other novel materials. Dynamic systems are being developed that use sensors and controls to modulate daylighting and shading contributions in response to occupancy, comfort and energy needs. Improving the energy performance of windows involves physics in a variety of application: optics, heat transfer, materials science and applied engineering. Technical solutions must also be compatible with national policy, codes and standards, economics, business practice and investment, real and perceived risks, comfort, health, safety, productivity, amenities, and occupant preference and values. The challenge is to optimize energy performance by understanding and reinforcing the synergetic coupling between these many issues.

Cyclodextrin-based supramolecular systems for drug delivery: Recent progress and future perspective

PubMed Central

Zhang, Jianxiang; Ma, Peter X

2013-01-01

The excellent biocompatibility and unique inclusion capability as well as powerful functionalization capacity of cyclodextrins and their derivatives make them especially attractive for engineering novel functional materials for biomedical applications. There has been increasing interest recently to fabricate supramolecular systems for drug and gene delivery based on cyclodextrin materials. This review focuses on state of the art and recent advances in the construction of cyclodextrin-based assemblies and their applications for controlled drug delivery. First, we introduce cyclodextrin materials utilized for self-assembly. The fabrication technologies of supramolecular systems including nanoplatforms and hydrogels as well as their applications in nanomedicine and pharmaceutical sciences are then highlighted. At the end, the future directions of this field are discussed. PMID:23673149

Biomineralization-inspired synthesis of functional organic/inorganic hybrid materials: organic molecular control of self-organization of hybrids.

PubMed

Arakaki, Atsushi; Shimizu, Katsuhiko; Oda, Mayumi; Sakamoto, Takeshi; Nishimura, Tatsuya; Kato, Takashi

2015-01-28

Organisms produce various organic/inorganic hybrid materials, which are called biominerals. They form through the self-organization of organic molecules and inorganic elements under ambient conditions. Biominerals often have highly organized and hierarchical structures from nanometer to macroscopic length scales, resulting in their remarkable physical and chemical properties that cannot be obtained by simple accumulation of their organic and inorganic constituents. These observations motivate us to create novel functional materials exhibiting properties superior to conventional materials--both synthetic and natural. Herein, we introduce recent progress in understanding biomineralization processes at the molecular level and the development of organic/inorganic hybrid materials by these processes. We specifically outline fundamental molecular studies on silica, iron oxide, and calcium carbonate biomineralization and describe material synthesis based on these mechanisms. These approaches allow us to design a variety of advanced hybrid materials with desired morphologies, sizes, compositions, and structures through environmentally friendly synthetic routes using functions of organic molecules.

New Comparative Measures of Income, Material Deprivation, and Well-Being

ERIC Educational Resources Information Center

Smeeding, Timothy M.

2009-01-01

Most societies, rich and poor, seek to measure progress in reducing poverty and need, as indicated by material deprivation or social exclusion. The yardsticks used to assess progress and policy impact mainly include income-based poverty, but broader measures of poverty based on consumption, wealth, and material deprivation are also now coming into…

Progress on CD-DVD laser microfabrication method to develop cell culture scaffolds integrating biomimetic characteristics

NASA Astrophysics Data System (ADS)

Hautefeuille, Mathieu; Vázquez-Victorio, Genaro; Cruz-Ramírez, Aaron; Cabriales, Lucia; Jiménez-Diaz, Edgar; Escutia-Guadarrama, Lidia; López-Aparicio, Jehú; Pérez-Calixto, Daniel; Cano-Jorge, Mariel; Nieto-Rivera, Brenda; Sánchez-Olvera, Raúl

2018-02-01

The development of organ-on-chip and biological scaffolds is currently requiring simpler methods to microstructure biocompatible materials in three dimensions, fabricate structural and functional elements in biomaterials or modify the physicochemical properties of desired substrates. With the aim of creating simple, cost-effective alternatives to conventional existing techniques to produce such platforms with very specific properties, a low-power CD-DVD laser pickup head was recycled and mounted on a programmable three-axis micro-displacement system in order to modify the surface of polymeric materials in a local fashion. Thanks to a specially-designed method using a strongly absorbing additive coating the materials of interest, it has been possible to establish and precisely control processes useful in microtechnology for biomedical applications and normally restricted to much less affordable high-power lasers. In this work, we present our latest progress regarding the application of our fabrication technique to the development of organ-on-chip platforms thanks to the simple integration of several biomimetic characteristics typically achieved with traditional, less cost-effective microtechnology methods in one step or through replica-molding. Our straightforward approach indeed enables great control of local laser microablation for true on-demand biomimetic micropatterned designs in several transparent polymers and hydrogels of tunable stiffness and is allowing integration of microfluidics, microelectronics, optical waveguides, surface microstructuring and even transfer of superficial protein micropatterns on a variety of biocompatible materials. The results presented here were validated using hepatic and fibroblasts cell lines to demonstrate the viability of our procedure for organ-on-chip development and show the impact of such features in cell culture.

Progress in advanced high temperature turbine materials, coatings, and technology

NASA Technical Reports Server (NTRS)

Freche, J. C.; Ault, G. M.

1977-01-01

Material categories as well as coatings and recent turbine cooling developments are reviewed. Current state of the art is identified, and as assessment, when appropriate, of progress, problems, and future directions is provided.

SYSTEM DESIGN FOR A CONTINUOUS PROGRESS SCHOOL--PART III, THE INSTRUCTIONAL MATERIALS CENTER.

ERIC Educational Resources Information Center

COGSWELL, JOHN F.; EGBERT, ROBERT L.

THE INSTRUCTIONAL MATERIALS CENTER (IMC) OF THE CONTINUOUS PROGRESS SCHOOL WAS DESCRIBED. THE CONTINUOUS PROGRESS SCHOOL PLAN WAS DEVISED BY DR. EDWIN READ AND WAS BEING DEVELOPED AT THE LABORATORY SCHOOL OF BRIGHAM YOUNG UNIVERSITY. THIS REPORT DESCRIBED HOW AN IMC MIGHT OPERATE RATHER THAN HOW ONE IS OPERATING OR IS PLANNED TO OPERATE. AS…

Quantum engineering of transistors based on 2D materials heterostructures

NASA Astrophysics Data System (ADS)

Iannaccone, Giuseppe; Bonaccorso, Francesco; Colombo, Luigi; Fiori, Gianluca

2018-03-01

Quantum engineering entails atom-by-atom design and fabrication of electronic devices. This innovative technology that unifies materials science and device engineering has been fostered by the recent progress in the fabrication of vertical and lateral heterostructures of two-dimensional materials and by the assessment of the technology potential via computational nanotechnology. But how close are we to the possibility of the practical realization of next-generation atomically thin transistors? In this Perspective, we analyse the outlook and the challenges of quantum-engineered transistors using heterostructures of two-dimensional materials against the benchmark of silicon technology and its foreseeable evolution in terms of potential performance and manufacturability. Transistors based on lateral heterostructures emerge as the most promising option from a performance point of view, even if heterostructure formation and control are in the initial technology development stage.

Patterning techniques for metal organic frameworks.

PubMed

Falcaro, Paolo; Buso, Dario; Hill, Anita J; Doherty, Cara M

2012-06-26

The tuneable pore size and architecture, chemical properties and functionalization make metal organic frameworks (MOFs) attractive versatile stimuli-responsive materials. In this context, MOFs hold promise for industrial applications and a fervent research field is currently investigating MOF properties for device fabrication. Although the material properties have a crucial role, the ability to precisely locate the functional material is fundamental for device fabrication. In this progress report, advancements in the control of MOF positioning and precise localization of functional materials within MOF crystals are presented. Advantages and limitations of each reviewed technique are critically investigated, and several important gaps in the technological development for device fabrication are highlighted. Finally, promising patterning techniques are presented which are inspired by previous studies in organic and inorganic crystal patterning for the future of MOF lithography. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantum engineering of transistors based on 2D materials heterostructures.

PubMed

Iannaccone, Giuseppe; Bonaccorso, Francesco; Colombo, Luigi; Fiori, Gianluca

2018-03-01

Quantum engineering entails atom-by-atom design and fabrication of electronic devices. This innovative technology that unifies materials science and device engineering has been fostered by the recent progress in the fabrication of vertical and lateral heterostructures of two-dimensional materials and by the assessment of the technology potential via computational nanotechnology. But how close are we to the possibility of the practical realization of next-generation atomically thin transistors? In this Perspective, we analyse the outlook and the challenges of quantum-engineered transistors using heterostructures of two-dimensional materials against the benchmark of silicon technology and its foreseeable evolution in terms of potential performance and manufacturability. Transistors based on lateral heterostructures emerge as the most promising option from a performance point of view, even if heterostructure formation and control are in the initial technology development stage.

Light Robots: Bridging the Gap between Microrobotics and Photomechanics in Soft Materials.

PubMed

Zeng, Hao; Wasylczyk, Piotr; Wiersma, Diederik S; Priimagi, Arri

2018-06-01

For decades, roboticists have focused their efforts on rigid systems that enable programmable, automated action, and sophisticated control with maximal movement precision and speed. Meanwhile, material scientists have sought compounds and fabrication strategies to devise polymeric actuators that are small, soft, adaptive, and stimuli-responsive. Merging these two fields has given birth to a new class of devices-soft microrobots that, by combining concepts from microrobotics and stimuli-responsive materials research, provide several advantages in a miniature form: external, remotely controllable power supply, adaptive motion, and human-friendly interaction, with device design and action often inspired by biological systems. Herein, recent progress in soft microrobotics is highlighted based on light-responsive liquid-crystal elastomers and polymer networks, focusing on photomobile devices such as walkers, swimmers, and mechanical oscillators, which may ultimately lead to flying microrobots. Finally, self-regulated actuation is proposed as a new pathway toward fully autonomous, intelligent light robots of the future. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polymeric Janus Nanoparticles: Recent Advances in Synthetic Strategies, Materials Properties, and Applications.

PubMed

Fan, Xiaoshan; Yang, Jing; Loh, Xian Jun; Li, Zibiao

2018-06-13

Polymeric Janus nanoparticles with two sides of incompatible chemistry have received increasing attention due to their tunable asymmetric structure and unique material characteristics. Recently, with the rapid progress in controlled polymerization combined with novel fabrication techniques, a large array of functional polymeric Janus particles are diversified with sophisticated architecture and applications. In this review, the most recently developed strategies for controlled synthesis of polymeric Janus nanoparticles with well-defined size and complex superstructures are summarized. In addition, the pros and cons of each approach in mediating the anisotropic shapes of polymeric Janus particles as well as their asymmetric spatial distribution of chemical compositions and functionalities are discussed and compared. Finally, these newly developed structural nanoparticles with specific shapes and surface functions orientated applications in different domains are also discussed, followed by the perspectives and challenges faced in the further advancement of polymeric Janus nanoparticles as high performance materials. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanomaterials derived from metal-organic frameworks

NASA Astrophysics Data System (ADS)

Dang, Song; Zhu, Qi-Long; Xu, Qiang

2018-01-01

The thermal transformation of metal-organic frameworks (MOFs) generates a variety of nanostructured materials, including carbon-based materials, metal oxides, metal chalcogenides, metal phosphides and metal carbides. These derivatives of MOFs have characteristics such as high surface areas, permanent porosities and controllable functionalities that enable their good performance in sensing, gas storage, catalysis and energy-related applications. Although progress has been made to tune the morphologies of MOF-derived structures at the nanometre scale, it remains crucial to further our knowledge of the relationship between morphology and performance. In this Review, we summarize the synthetic strategies and optimized methods that enable control over the size, morphology, composition and structure of the derived nanomaterials. In addition, we compare the performance of materials prepared by the MOF-templated strategy and other synthetic methods. Our aim is to reveal the relationship between the morphology and the physico-chemical properties of MOF-derived nanostructures to optimize their performance for applications such as sensing, catalysis, and energy storage and conversion.

AGOR 28: SIO Shipyard Representative Bi-Weekly Progress Report

DTIC Science & Technology

2014-10-09

material. • Hi-Fog and emergency shutdowns – the Pilot House (SCC) has been designated as the main fire control station per ACCU. For this reason, the...decision. In addition, because of the ACCU designation , other required emergency shutdowns will also be located at the SCC. These include remote...3 • Foc’sle Deck Joiner & HVAC – Additional joiner work taking place and several large HVAC duct runs installed

Design, Fabrication, and In Vitro Testing of an Anti-biofouling Glaucoma Micro-shunt.

PubMed

Harake, Ryan S; Ding, Yuzhe; Brown, J David; Pan, Tingrui

2015-10-01

Glaucoma, one of the leading causes of irreversible blindness, is a progressive neurodegenerative disease. Chronic elevated intraocular pressure (IOP), a prime risk factor for glaucoma, can be treated by aqueous shunts, implantable devices, which reduce IOP in glaucoma patients by providing alternative aqueous outflow pathways. Although initially effective at delaying glaucoma progression, contemporary aqueous shunts often lead to numerous complications and only 50% of implanted devices remain functional after 5 years. In this work, we introduce a novel micro-device which provides an innovative platform for IOP reduction in glaucoma patients. The device design features an array of parallel micro-channels to provide precision aqueous outflow resistance control. Additionally, the device's microfluidic channels are composed of a unique combination of polyethylene glycol materials in order to provide enhanced biocompatibility and resistance to problematic channel clogging from biofouling of aqueous proteins. The microfabrication process employed to produce the devices results in additional advantages such as enhanced device uniformity and increased manufacturing throughput. Surface characterization experimental results show the device's surfaces exhibit significantly less non-specific protein adsorption compared to traditional implant materials. Results of in vitro flow experiments verify the device's ability to provide aqueous resistance control, continuous long-term stability through 10-day protein flow testing, and safety from risk of infection due to bacterial ingression.

Recent Progress in Advanced Materials for Lithium Ion Batteries

PubMed Central

Chen, Jiajun

2013-01-01

The development and commercialization of lithium ion batteries is rooted in material discovery. Promising new materials with high energy density are required for achieving the goal toward alternative forms of transportation. Over the past decade, significant progress and effort has been made in developing the new generation of Li-ion battery materials. In the review, I will focus on the recent advance of tin- and silicon-based anode materials. Additionally, new polyoxyanion cathodes, such as phosphates and silicates as cathode materials, will also be discussed. PMID:28809300

Assessment of Pulmonary Artery Stiffness of Repaired Congenital Heart Disease Patients

NASA Astrophysics Data System (ADS)

Lee, Namheon; Banerjee, Rajit; Taylor, Michael; Hor, Kan

2012-10-01

Surgical correction or palliation of congenital heart disease (CHD) often requires augmenting the main pulmonary artery (MPA) with non-native material or placing a cylindrical graft. The degree to which this intervention affects PA compliance is largely unknown. In this study, the MPA stiffness characteristics were assessed by its compliance, distensibility, and pressure-strain modulus. Coregistered velocity encoded phase-contrast MRI and cardiac catheterization data were available for a cohort of repaired CHD patients (n=8) and controls (n=3). All patients were repaired with either an RV-PA conduit or a RV outflow tract patch. We measured the MPA area change by MRI and MPA pressure during the cath. The measurements were taken through or just distal to the conduit. The MPA compliance and distensibility for the patients were significantly lower than the controls: compliance (9.8±10.8 vs 28.3±7.7mm^2/mmHg, p<0.05), distensibility (2.2±1.5 vs 6.6±2.1%Area change/mmHg, p=0.05). The patients had a significantly higher pressure-strain modulus (152.3±116.4mmHg, p<0.05) than the controls (35.8±10.6mmHg). The abnormally elevated PA stiffness due to the rigidity of the conduit or patch material may cause a compliance mismatch resulting in high stress levels contributing to the observed progressive PA dilatation. This may be a factor in the progressive RV dilatation seen in this cohort of repaired CHD patients.

Inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS for isotope analysis of long-lived radionuclides

NASA Astrophysics Data System (ADS)

Becker, J. Sabine

2005-04-01

For a few years now inductively coupled plasma mass spectrometry has been increasingly used for precise and accurate determination of isotope ratios of long-lived radionuclides at the trace and ultratrace level due to its excellent sensitivity, good precision and accuracy. At present, ICP-MS and also laser ablation ICP-MS are applied as powerful analytical techniques in different fields such as the characterization of nuclear materials, recycled and by-products (e.g., spent nuclear fuel or depleted uranium ammunitions), radioactive waste control, in environmental monitoring and in bioassay measurements, in health control, in geochemistry and geochronology. Especially double-focusing sector field ICP mass spectrometers with single ion detector or with multiple ion collector device have been used for the precise determination of long-lived radionuclides isotope ratios at very low concentration levels. Progress has been achieved by the combination of ultrasensitive mass spectrometric techniques with effective separation and enrichment procedures in order to improve detection limits or by the introduction of the collision cell in ICP-MS for reducing disturbing interfering ions (e.g., of 129Xe+ for the determination of 129I). This review describes the state of the art and the progress of ICP-MS and laser ablation ICP-MS for isotope ratio measurements of long-lived radionuclides in different sample types, especially in the main application fields of characterization of nuclear and radioactive waste material, environmental research and health controls.

AMPED Program Overview

ScienceCinema

Gur, Ilan

2018-01-16

An overview presentation about ARPA-E's AMPED program. AMPED projects seek to develop advanced sensing, control, and power management technologies that redefine the way we think about battery management. Energy storage can significantly improve U.S. energy independence, efficiency, and security by enabling a new generation of electric vehicles. While rapid progress is being made in new battery materials and storage technologies, few innovations have emerged in the management of advanced battery systems. AMPED aims to unlock enormous untapped potential in the performance, safety, and lifetime of today's commercial battery systems exclusively through system-level innovations, and is thus distinct from existing efforts to enhance underlying battery materials and architectures.

Validation of a New Elastoplastic Constitutive Model Dedicated to the Cyclic Behaviour of Brittle Rock Materials

NASA Astrophysics Data System (ADS)

Cerfontaine, B.; Charlier, R.; Collin, F.; Taiebat, M.

2017-10-01

Old mines or caverns may be used as reservoirs for fuel/gas storage or in the context of large-scale energy storage. In the first case, oil or gas is stored on annual basis. In the second case pressure due to water or compressed air varies on a daily basis or even faster. In both cases a cyclic loading on the cavern's/mine's walls must be considered for the design. The complexity of rockwork geometries or coupling with water flow requires finite element modelling and then a suitable constitutive law for the rock behaviour modelling. This paper presents and validates the formulation of a new constitutive law able to represent the inherently cyclic behaviour of rocks at low confinement. The main features of the behaviour evidenced by experiments in the literature depict a progressive degradation and strain of the material with the number of cycles. A constitutive law based on a boundary surface concept is developed. It represents the brittle failure of the material as well as its progressive degradation. Kinematic hardening of the yield surface allows the modelling of cycles. Isotropic softening on the cohesion variable leads to the progressive degradation of the rock strength. A limit surface is introduced and has a lower opening than the bounding surface. This surface describes the peak strength of the material and allows the modelling of a brittle behaviour. In addition a fatigue limit is introduced such that no cohesion degradation occurs if the stress state lies inside this surface. The model is validated against three different rock materials and types of experiments. Parameters of the constitutive laws are calibrated against uniaxial tests on Lorano marble, triaxial test on a sandstone and damage-controlled test on Lac du Bonnet granite. The model is shown to reproduce correctly experimental results, especially the evolution of strain with number of cycles.

Multi-material composites prepared by additive manufacturing and melt casting

NASA Astrophysics Data System (ADS)

Murialdo, Maxwell; Sullivan, Kyle; White, Bradley; LLNL MSD Collaboration

2017-06-01

Recent advances in additive manufacturing have disrupted not only means of production, but also have enabled a new parameter space of multiscale materials designs. Understanding the role of architecture to control material response is being investigated for a wide range of applications, from light-weight structural components to energetic materials. In this work, we combine 3D printing of scaffold structures with a subsequent melt-infiltration step to render an architected multi-material composite article. Both the scaffold architecture and material type were investigated. The processing challenges of filling such scaffolds using a melt-infiltration step will be discussed, along with our progress in this area. Using the combined method of printing and casting, we will discuss our path forward for testing the mechanical properties and the high-strain response of our composite architected parts. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. IM release: LLNL-ABS-725497-DRAFT.

Bandgap engineering in semiconductor alloy nanomaterials with widely tunable compositions

NASA Astrophysics Data System (ADS)

Ning, Cun-Zheng; Dou, Letian; Yang, Peidong

2017-12-01

Over the past decade, tremendous progress has been achieved in the development of nanoscale semiconductor materials with a wide range of bandgaps by alloying different individual semiconductors. These materials include traditional II-VI and III-V semiconductors and their alloys, inorganic and hybrid perovskites, and the newly emerging 2D materials. One important common feature of these materials is that their nanoscale dimensions result in a large tolerance to lattice mismatches within a monolithic structure of varying composition or between the substrate and target material, which enables us to achieve almost arbitrary control of the variation of the alloy composition. As a result, the bandgaps of these alloys can be widely tuned without the detrimental defects that are often unavoidable in bulk materials, which have a much more limited tolerance to lattice mismatches. This class of nanomaterials could have a far-reaching impact on a wide range of photonic applications, including tunable lasers, solid-state lighting, artificial photosynthesis and new solar cells.

Removal of Organic Pollutants from Water Using Superwetting Materials.

PubMed

Li, Lingxiao; Zhang, Junping; Wang, Aiqin

2018-02-01

The frequent occurrence of water pollution accidents and the leakage of organic pollutants have caused severe environmental and ecological crisis. It is thus highly imperative to find efficient materials to solve the problem. Inspired by the lotus leaf, superwetting materials are receiving increasing attention in the field of removal of organic pollutants from water. Various superwetting materials have been successfully generated and integrated into devices for removal of organic pollutants from water. On the basis of our previous work in the field, we summarized in this account the progress of removal of (1) floating and underwater insoluble, (2) emulsified insoluble, and (3) both insoluble and soluble organic pollutants from water using superwetting materials including superhydrophobic & superoleophilic materials, superhydrophilic & underwater superoleophobic materials, and materials with controllable wettability. The superwetting materials are in the forms of 2D porous materials, 3D porous materials and particles, etc. Finally, the current state and future challenges in this field are discussed. We hope this account could shed light on the design of novel superwetting materials for efficient removal of organic pollutants from water. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cold molecules: Progress in quantum engineering of chemistry and quantum matter

NASA Astrophysics Data System (ADS)

Bohn, John L.; Rey, Ana Maria; Ye, Jun

2017-09-01

Cooling atoms to ultralow temperatures has produced a wealth of opportunities in fundamental physics, precision metrology, and quantum science. The more recent application of sophisticated cooling techniques to molecules, which has been more challenging to implement owing to the complexity of molecular structures, has now opened the door to the longstanding goal of precisely controlling molecular internal and external degrees of freedom and the resulting interaction processes. This line of research can leverage fundamental insights into how molecules interact and evolve to enable the control of reaction chemistry and the design and realization of a range of advanced quantum materials.

Operational considerations for laminar flow aircraft

NASA Technical Reports Server (NTRS)

Maddalon, Dal V.; Wagner, Richard D.

1986-01-01

Considerable progress has been made in the development of laminar flow technology for commercial transports during the NASA Aircraft Energy Efficiency (ACEE) laminar flow program. Practical, operational laminar flow control (LFC) systems have been designed, fabricated, and are undergoing flight testing. New materials, fabrication methods, analysis techniques, and design concepts were developed and show much promise. The laminar flow control systems now being flight tested on the NASA Jetstar aircraft are complemented by natural laminar flow flight tests to be accomplished with the F-14 variable-sweep transition flight experiment. An overview of some operational aspects of this exciting program is given.

Technologies for Controlled, Local Delivery of siRNA

PubMed Central

Sarett, Samantha M.; Nelson, Christopher E.; Duvall, Craig L.

2015-01-01

The discovery of RNAi in the late 1990s unlocked a new realm of therapeutic possibilities by enabling potent and specific silencing of theoretically any desired genetic target. Better elucidation of the mechanism of action, the impact of chemical modifications that stabilize and reduce nonspecific effects of siRNA molecules, and the key design considerations for effective delivery systems has spurred progress toward developing clinically-successful siRNA therapies. A logical aim for initial siRNA translation is local therapies, as delivering siRNA directly to its site of action helps to ensure that a sufficient dose reaches the target tissue, lessens the potential for off-target side effects, and circumvents the substantial systemic delivery barriers. While topical siRNA delivery has progressed into numerous clinical trials, an enormous opportunity also exists to develop sustained-release, local delivery systems that enable both spatial and temporal control of gene silencing. This review focuses on material platforms that establish both localized and controlled gene silencing, with emphasis on the systems that show most promise for clinical translation. PMID:26476177

Computationally guided discovery of thermoelectric materials

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

Gorai, Prashun; Stevanović, Vladan; Toberer, Eric S.

The potential for advances in thermoelectric materials, and thus solid-state refrigeration and power generation, is immense. Progress so far has been limited by both the breadth and diversity of the chemical space and the serial nature of experimental work. In this Review, we discuss how recent computational advances are revolutionizing our ability to predict electron and phonon transport and scattering, as well as materials dopability, and we examine efficient approaches to calculating critical transport properties across large chemical spaces. When coupled with experimental feedback, these high-throughput approaches can stimulate the discovery of new classes of thermoelectric materials. Within smaller materialsmore » subsets, computations can guide the optimal chemical and structural tailoring to enhance materials performance and provide insight into the underlying transport physics. Beyond perfect materials, computations can be used for the rational design of structural and chemical modifications (such as defects, interfaces, dopants and alloys) to provide additional control on transport properties to optimize performance. Through computational predictions for both materials searches and design, a new paradigm in thermoelectric materials discovery is emerging.« less

Recent progress of atomic layer deposition on polymeric materials.

PubMed

Guo, Hong Chen; Ye, Enyi; Li, Zibiao; Han, Ming-Yong; Loh, Xian Jun

2017-01-01

As a very promising surface coating technology, atomic layer deposition (ALD) can be used to modify the surfaces of polymeric materials for improving their functions and expanding their application areas. Polymeric materials vary in surface functional groups (number and type), surface morphology and internal structure, and thus ALD deposition conditions that typically work on a normal solid surface, usually do not work on a polymeric material surface. To date, a large variety of research has been carried out to investigate ALD deposition on various polymeric materials. This paper aims to provide an in-depth review of ALD deposition on polymeric materials and its applications. Through this review, we will provide a better understanding of surface chemistry and reaction mechanism for controlled surface modification of polymeric materials by ALD. The integrated knowledge can aid in devising an improved way in the reaction between reactant precursors and polymer functional groups/polymer backbones, which will in turn open new opportunities in processing ALD materials for better inorganic/organic film integration and potential applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Computationally guided discovery of thermoelectric materials

DOE PAGES

Gorai, Prashun; Stevanović, Vladan; Toberer, Eric S.

2017-08-22

The potential for advances in thermoelectric materials, and thus solid-state refrigeration and power generation, is immense. Progress so far has been limited by both the breadth and diversity of the chemical space and the serial nature of experimental work. In this Review, we discuss how recent computational advances are revolutionizing our ability to predict electron and phonon transport and scattering, as well as materials dopability, and we examine efficient approaches to calculating critical transport properties across large chemical spaces. When coupled with experimental feedback, these high-throughput approaches can stimulate the discovery of new classes of thermoelectric materials. Within smaller materialsmore » subsets, computations can guide the optimal chemical and structural tailoring to enhance materials performance and provide insight into the underlying transport physics. Beyond perfect materials, computations can be used for the rational design of structural and chemical modifications (such as defects, interfaces, dopants and alloys) to provide additional control on transport properties to optimize performance. Through computational predictions for both materials searches and design, a new paradigm in thermoelectric materials discovery is emerging.« less

Payload Safety: Risk and Characteristic-Based Control of Engineered Nanomaterials

NASA Astrophysics Data System (ADS)

Abou, Seraphin Chally; Saad, Maarouf

2013-09-01

In the last decade progress has been made to assist organizations that are developing payloads intended for flight on the International Space Station (ISS) and/or Space Shuttle. Collaboration programs for comprehensive risk assessment have been initiated between the U.S. and the European Union to generate requirements and data needed to comply with payloads safety and to perform risk assessment and controls guidance. Yet, substantial research gaps remain, as do challenges in the translation of these research findings to control for exposure to nanoscale material payloads, and the health effects. Since nanomaterial structures are different from traditional molecules, some standard material properties can change at size of 50nm or less. Changes in material properties at this scale challenge our understanding of hazards posed by nanomaterial payloads in the ISS realistic exposure conditions, and our ability to anticipate, evaluate, and control potential health issues, and safety. The research question addressed in this framework is: what kind of descriptors can be developed for nanomaterial payloads risks assessment? Methods proposed incorporate elements of characteristic- based risk an alysis: (1) to enable characterization of anthropogenic nanomaterials which can result in incidental from natural nanoparticles; and (2) to better understand safety attributes in terms of human health impacts from exposure to varying types of engineered nanomaterials.

Clinical benefit of continuing crizotinib therapy after initial disease progression in Chinese patients with advanced ALK-rearranged non-small-cell lung cancer

PubMed Central

Hong, Xiangchan; Chen, Qi; Ding, Lingyu; Liang, Ying; Zhou, Ningning; Fang, Wenfeng; Chen, Xinru; Wu, Haiying

2017-01-01

Purpose Although most patients with ALK-positive non?small-cell lung cancer (NSCLC) who benefit from treatment with crizotinib ultimately develop progressive disease (PD), continuing crizotinb beyond the initial PD (CBPD) in these patients may be beneficial. In this study, we investigated whether Chinese patients with advanced ALK-positive NSCLC benefit from CBPD, and whether any factors are predictive of a longer post-initial progression-free survival time (PFS2). Materials and Methods Data on 33 patients with ALK-positive NSCLC who achieved disease control with crizotinib were analyzed retrospectively. The impact of continued crizotinib therapy on the patients’ PFS2 time was assessed after adjusting for potential confounding factors. Results With initial crizotinib therapy, the objective response rate (ORR) and median PFS time (PFS1) in the 33 patients were 63.6% and 8.6 months, respectively. With continued crizotinib therapy after documentation of PD, the median PFS2 for all 33 patients was 16 weeks, and in those with CNS progression but systemic disease control it was 30 weeks. Patients who received local therapy after disease progression had a significantly longer PFS2 compared with those who did not (P = 0.039). Multivariable Cox regression analysis showed that the PFS1 with initial crizotinib treatment and local therapy were independent predictors of PFS2. Discussion This study provides further evidence of the benefit of continuing crizotinib therapy in Chinese patients with progressive ALK-positive NSCLC. Patients with a longer PFS1 and those who received local brain therapy would have a longer period of continuing crizotinib. PMID:28427213

Understanding the Atomic Scale Mechanisms that Control the Attainment of Ultralow Friction and Wear in Carbon-Based Materials

DTIC Science & Technology

2016-01-16

These characteristics far exceed those of well-lubricated interfaces of high performance steels and other expensive coatings. Despite this potential...the sharpness of these tips is a necessary characteristic to probe the high-stress wear regime. We also made progress in studying boron -doped UNCD... Boron -doping endows UNCD with electrical conductivity, which broadens its applications including for contact electrode applications, for example

Nucleation and phase transformation pathways in electrolyte solutions investigated by in situ microscopy techniques

DOE PAGES

Tao, Jinhui; Nielsen, Michael H.; De Yoreo, James J.

2018-04-27

Identification of crystal nucleation and growth pathways is of fundamental importance for synthesis of functional materials, which requires control over size, orientation, polymorph, and hierarchical structure, often in the presence of additives used to tune the energy landscape defining these pathways. Furthermore we summarize the recent progress in application of in situ TEM and AFM techniques to monitor or even tune the pathway of crystal nucleation and growth.

Nucleation and phase transformation pathways in electrolyte solutions investigated by in situ microscopy techniques

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

Tao, Jinhui; Nielsen, Michael H.; De Yoreo, James J.

Identification of crystal nucleation and growth pathways is of fundamental importance for synthesis of functional materials, which requires control over size, orientation, polymorph, and hierarchical structure, often in the presence of additives used to tune the energy landscape defining these pathways. Furthermore we summarize the recent progress in application of in situ TEM and AFM techniques to monitor or even tune the pathway of crystal nucleation and growth.

A-D-A small molecules for solution-processed organic photovoltaic cells.

PubMed

Ni, Wang; Wan, Xiangjian; Li, Miaomiao; Wang, Yunchuang; Chen, Yongsheng

2015-03-25

A-D-A small molecules have drawn more and more attention in solution-processed organic solar cells due to the advantages of a diversity of structures, easy control of energy levels, etc. Recently, a power conversion efficiency of nearly 10% has been achieved through careful material design and device optimization. This feature article reviews recent representative progress in the design and application of A-D-A small molecules in organic photovoltaic cells.

Nondestructive detection and measurement of hydrogen embrittlement

DOEpatents

Alex, Franklin; Byrne, Joseph Gerald

1977-01-01

A nondestructive system and method for the determination of the presence and extent of hydrogen embrittlement in metals, alloys, and other crystalline structures subject thereto. Positron annihilation characteristics of the positron-electron annihilation within the tested material provide unique energy distribution curves for each type of material tested at each respective stage of hydrogen embrittlement. Gamma radiation resulting from such annihilation events is detected and statistically summarized by appropriate instrumentation to reveal the variations of electron activity within the tested material caused by hydrogen embrittlement therein. Such data from controlled tests provides a direct indication of the relative stages of hydrogen embrittlement in the form of unique energy distribution curves which may be utilized as calibration curves for future comparison with field tests to give on-site indication of progressive stages of hydrogen embrittlement.

Toward superconducting critical current by design

DOE PAGES

Sadovskyy, Ivan A.; Jia, Ying; Leroux, Maxime; ...

2016-03-31

The interaction of vortex matter with defects in applied superconductors directly determines their current carrying capacity. Defects range from chemically grown nanostructures and crystalline imperfections to the layered structure of the material itself. The vortex-defect interactions are non-additive in general, leading to complex dynamic behavior that has proven difficult to capture in analytical models. With recent rapid progress in computational powers, a new paradigm has emerged that aims at simulation assisted design of defect structures with predictable ‘critical-current-by-design’: analogous to the materials genome concept of predicting stable materials structures of interest. We demonstrate the feasibility of this paradigm by combiningmore » large-scale time-dependent Ginzburg-Landau numerical simulations with experiments on commercial high temperature superconductor (HTS) containing well-controlled correlated defects.« less

An overview of molecular acceptors for organic solar cells

NASA Astrophysics Data System (ADS)

Hudhomme, Piétrick

2013-07-01

Organic solar cells (OSCs) have gained serious attention during the last decade and are now considered as one of the future photovoltaic technologies for low-cost power production. The first dream of attaining 10% of power coefficient efficiency has now become a reality thanks to the development of new materials and an impressive work achieved to understand, control and optimize structure and morphology of the device. But most of the effort devoted to the development of new materials concerned the optimization of the donor material, with less attention for acceptors which to date remain dominated by fullerenes and their derivatives. This short review presents the progress in the use of non-fullerene small molecules and fullerene-based acceptors with the aim of evaluating the challenge for the next generation of acceptors in organic photovoltaics.

Design Concept of Dialyzer Biomaterials: How to Find Biocompatible Polymers Based on the Biointerfacial Water Structure.

PubMed

Tanaka, Masaru

2017-01-01

Although various types of materials have been used widely in dialyzers, most biomaterials lack the desired functional properties to interface with blood and have not been engineered for optimum performance. Therefore, there is increasing demand to develop novel materials to address such problems in the dialysis arena. Numerous parameters of polymeric biomaterials can affect biocompatibility in a controlled manner. The mechanisms responsible for the biocompatibility of polymers at the molecular level have not been clearly demonstrated, although many theoretical and experimental efforts have been made to try and understand them. Moreover, water interactions have been recognized as fundamental for the blood response to contact with polymers. We have proposed the 'intermediate water' concept and hypothesized that intermediate water, which prevents the proteins and blood cells from directly contacting the polymer surface, or nonfreezing water on the polymer surface, plays an important role in the biocompatibility of polymers. This chapter provides an overview of the recent experimental progress of biocompatible polymers measured by thermal, spectroscopic, and surface force techniques. Additionally, it highlights recent developments in the use of biocompatible polymeric biomaterials for dialyzers and provides an overview of the progress made in the design of multifunctional biomedical polymers by controlling the biointerfacial water structure through precision polymer synthesis. Key Messages: Intermediate water was found only in hydrated biopolymers (proteins, polysaccharides, and nucleic acids, DNA and RNA) and hydrated biocompatible synthetic polymers. Intermediate water could be one of the main screening factors for the design of appropriate dialyzer materials. © 2017 S. Karger AG, Basel.

Plasma under control: Advanced solutions and perspectives for plasma flux management in material treatment and nanosynthesis

NASA Astrophysics Data System (ADS)

Baranov, O.; Bazaka, K.; Kersten, H.; Keidar, M.; Cvelbar, U.; Xu, S.; Levchenko, I.

2017-12-01

Given the vast number of strategies used to control the behavior of laboratory and industrially relevant plasmas for material processing and other state-of-the-art applications, a potential user may find themselves overwhelmed with the diversity of physical configurations used to generate and control plasmas. Apparently, a need for clearly defined, physics-based classification of the presently available spectrum of plasma technologies is pressing, and the critically summary of the individual advantages, unique benefits, and challenges against key application criteria is a vital prerequisite for the further progress. To facilitate selection of the technological solutions that provide the best match to the needs of the end user, this work systematically explores plasma setups, focusing on the most significant family of the processes—control of plasma fluxes—which determine the distribution and delivery of mass and energy to the surfaces of materials being processed and synthesized. A novel classification based on the incorporation of substrates into plasma-generating circuitry is also proposed and illustrated by its application to a wide variety of plasma reactors, where the effect of substrate incorporation on the plasma fluxes is emphasized. With the key process and material parameters, such as growth and modification rates, phase transitions, crystallinity, density of lattice defects, and others being linked to plasma and energy fluxes, this review offers direction to physicists, engineers, and materials scientists engaged in the design and development of instrumentation for plasma processing and diagnostics, where the selection of the correct tools is critical for the advancement of emerging and high-performance applications.

Advanced Plasmonic Materials for Dynamic Color Display.

PubMed

Shao, Lei; Zhuo, Xiaolu; Wang, Jianfang

2018-04-01

Plasmonic structures exhibit promising applications in high-resolution and durable color generation. Research on advanced hybrid plasmonic materials that allow dynamically reconfigurable color control has developed rapidly in recent years. Some of these results may give rise to practically applicable reflective displays in living colors with high performance and low power consumption. They will attract broad interest from display markets, compared with static plasmonic color printing, for example, in applications such as digital signage, full-color electronic paper, and electronic device screens. In this progress report, the most promising recent examples of utilizing advanced plasmonic materials for the realization of dynamic color display are highlighted and put into perspective. The performances, advantages, and disadvantages of different technologies are discussed, with emphasis placed on both the potential and possible limitations of various hybrid materials for dynamic plasmonic color display. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Novel Application of Ultrasonic Imaging to Study Smoldering Combustion

NASA Technical Reports Server (NTRS)

Tse, S. D.; Anthenien, R. A.; Fernandez-Pello, A. Carlos; Miyasaka, K.

1997-01-01

An ultrasonic imaging technique has been developed to examine the propagation of a smolder reaction within a porous combustible material. The technique provides information about the location of a propagating smolder front, as well as line-of-sight average permeability variations of the smoldering material. The method utilizes the observation that transmission of an ultrasonic signal through a porous material increases with permeability. Since a propagating smolder reaction leaves behind char with a higher permeability than the original material, ultrasound transmission can be employed to monitor smolder progress. The technique can also be used to track the char evolution as it continues to react. Experiments are presented where the technique is applied to smoldering combustion in a two-dimensional geometry. The results have furthered the understanding of two-dimensional smolder, especially in identifying the controlling mechanisms leading to the transition from smoldering to flaming. The applicability of ultrasonic tomography to smoldering combustion has also been investigated.

Hydrogels in a historical perspective: from simple networks to smart materials.

PubMed

Buwalda, Sytze J; Boere, Kristel W M; Dijkstra, Pieter J; Feijen, Jan; Vermonden, Tina; Hennink, Wim E

2014-09-28

Over the past decades, significant progress has been made in the field of hydrogels as functional biomaterials. Biomedical application of hydrogels was initially hindered by the toxicity of crosslinking agents and limitations of hydrogel formation under physiological conditions. Emerging knowledge in polymer chemistry and increased understanding of biological processes resulted in the design of versatile materials and minimally invasive therapies. Hydrogel matrices comprise a wide range of natural and synthetic polymers held together by a variety of physical or chemical crosslinks. With their capacity to embed pharmaceutical agents in their hydrophilic crosslinked network, hydrogels form promising materials for controlled drug release and tissue engineering. Despite all their beneficial properties, there are still several challenges to overcome for clinical translation. In this review, we provide a historical overview of the developments in hydrogel research from simple networks to smart materials. Copyright © 2014 Elsevier B.V. All rights reserved.

The potential of composite cognitive scores for tracking progression in Huntington's disease.

PubMed

Jones, Rebecca; Stout, Julie C; Labuschagne, Izelle; Say, Miranda; Justo, Damian; Coleman, Allison; Dumas, Eve M; Hart, Ellen; Owen, Gail; Durr, Alexandra; Leavitt, Blair R; Roos, Raymund; O'Regan, Alison; Langbehn, Doug; Tabrizi, Sarah J; Frost, Chris

2014-01-01

Composite scores derived from joint statistical modelling of individual risk factors are widely used to identify individuals who are at increased risk of developing disease or of faster disease progression. We investigated the ability of composite measures developed using statistical models to differentiate progressive cognitive deterioration in Huntington's disease (HD) from natural decline in healthy controls. Using longitudinal data from TRACK-HD, the optimal combinations of quantitative cognitive measures to differentiate premanifest and early stage HD individuals respectively from controls was determined using logistic regression. Composite scores were calculated from the parameters of each statistical model. Linear regression models were used to calculate effect sizes (ES) quantifying the difference in longitudinal change over 24 months between premanifest and early stage HD groups respectively and controls. ES for the composites were compared with ES for individual cognitive outcomes and other measures used in HD research. The 0.632 bootstrap was used to eliminate biases which result from developing and testing models in the same sample. In early HD, the composite score from the HD change prediction model produced an ES for difference in rate of 24-month change relative to controls of 1.14 (95% CI: 0.90 to 1.39), larger than the ES for any individual cognitive outcome and UHDRS Total Motor Score and Total Functional Capacity. In addition, this composite gave a statistically significant difference in rate of change in premanifest HD compared to controls over 24-months (ES: 0.24; 95% CI: 0.04 to 0.44), even though none of the individual cognitive outcomes produced statistically significant ES over this period. Composite scores developed using appropriate statistical modelling techniques have the potential to materially reduce required sample sizes for randomised controlled trials.

Progress in electrochemical storage for battery systems

NASA Technical Reports Server (NTRS)

Ford, F. E.; Hennigan, T. J.; Palandati, C. F.; Cohn, E.

1972-01-01

Efforts to improve electrochemical systems for space use relate to: (1) improvement of conventional systems; (2) development of fuel cells to practical power systems; and (3) a search for new systems that provide gains in energy density but offer comparable life and performance as conventional systems. Improvements in sealed conventional systems resulted in the areas of materials, charge control methods, cell operations and battery control, and specific process controls required during cell manufacture. Fuel-cell systems have been developed for spacecraft but the use of these power plants is limited. For present and planned flights, nickel-cadmium, silver-zinc, and silver-cadmium systems will be used. Improvements in nickel-cadmium batteries have been applied in medical and commercial areas.

Gas-Cooled Reactor Programs annual progress report for period ending December 31, 1973. [HTGR fuel reprocessing, fuel fabrication, fuel irradiation, core materials, and fission product distribution; GCFR fuel irradiation and steam generator modeling

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

Kasten, P.R.; Coobs, J.H.; Lotts, A.L.

1976-04-01

Progress is summarized in studies relating to HTGR fuel reprocessing, refabrication, and recycle; HTGR fuel materials development and performance testing; HTGR PCRV development; HTGR materials investigations; HTGR fuel chemistry; HTGR safety studies; and GCFR irradiation experiments and steam generator modeling.

Controlled Release from Recombinant Polymers

PubMed Central

Price, Robert; Poursaid, Azadeh; Ghandehari, Hamidreza

2014-01-01

Recombinant polymers provide a high degree of molecular definition for correlating structure with function in controlled release. The wide array of amino acids available as building blocks for these materials lend many advantages including biorecognition, biodegradability, potential biocompatibility, and control over mechanical properties among other attributes. Genetic engineering and DNA manipulation techniques enable the optimization of structure for precise control over spatial and temporal release. Unlike the majority of chemical synthetic strategies used, recombinant DNA technology has allowed for the production of monodisperse polymers with specifically defined sequences. Several classes of recombinant polymers have been used for controlled drug delivery. These include, but are not limited to, elastin-like, silk-like, and silk-elastinlike proteins, as well as emerging cationic polymers for gene delivery. In this article, progress and prospects of recombinant polymers used in controlled release will be reviewed. PMID:24956486

Detecting errors and anomalies in computerized materials control and accountability databases

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

Whiteson, R.; Hench, K.; Yarbro, T.

The Automated MC and A Database Assessment project is aimed at improving anomaly and error detection in materials control and accountability (MC and A) databases and increasing confidence in the data that they contain. Anomalous data resulting in poor categorization of nuclear material inventories greatly reduces the value of the database information to users. Therefore it is essential that MC and A data be assessed periodically for anomalies or errors. Anomaly detection can identify errors in databases and thus provide assurance of the integrity of data. An expert system has been developed at Los Alamos National Laboratory that examines thesemore » large databases for anomalous or erroneous data. For several years, MC and A subject matter experts at Los Alamos have been using this automated system to examine the large amounts of accountability data that the Los Alamos Plutonium Facility generates. These data are collected and managed by the Material Accountability and Safeguards System, a near-real-time computerized nuclear material accountability and safeguards system. This year they have expanded the user base, customizing the anomaly detector for the varying requirements of different groups of users. This paper describes the progress in customizing the expert systems to the needs of the users of the data and reports on their results.« less

Development of Advanced Ods Ferritic Steels for Fast Reactor Fuel Cladding

NASA Astrophysics Data System (ADS)

Ukai, S.; Oono, N.; Ohtsuka, S.; Kaito, T.

Recent progress of the 9CrODS steel development is presented focusing on their microstructure control to improve sufficient high-temperature strength as well as cladding manufacturing capability. The martensitic 9CrODS steel is primarily candidate cladding materials for the Generation IV fast reactor fuel. They are the attractive composite-like materials consisting of the hard residual ferrite and soft tempered martensite, which are able to be easily controlled by α-γ phase transformation. The residual ferrite containing extremely nanosized oxide particles leads to significantly improved creep rupture strength in 9CrODS cladding. The creep strength stability at extended time of 60,000 h at 700 ºC is ascribed to the stable nanosized oxide particles. It was also reviewed that 9CrODS steel has well irradiation stability and fuel pin irradiation test was conducted up to 12 at% burnup and 51 dpa at the cladding temperature of 700ºC.

Bactericidal Activity of Usnic Acid-Loaded Electrospun Fibers.

PubMed

Araújo, Evando S; Pereira, Eugênia C; da Costa, Mateus M; da Silva, Nicácio H; de Oliveira, Helinando P

2016-01-01

Usnic acid has been progressively reported in the literature as one of the most important lichen metabolites characterized by a rich diversity of applications such as antifungal, antimicrobial, antiprotozoal and antiviral agent. Particularly, antimicrobial activity of usnic acid can be improved by encapsulation of active molecules in enteric electrospun fibers, allowing the controlled release of active molecule at specific pH. Few relevant patents to the topic have been reviewed and cited. Bactericidal activity of usnic acid-loaded electrospun fibers of Eudragit L-100 and polyvinylpyrrolidone was examined against Staphylococcus aureus using inhibition hales methodology. The controlled release of active material at high pH is established after 10 minutes of interaction with media and results in reasonable activity against S. aureus, as detected by inhibition hales. The strong biological activity of usnic acid-loaded electrospun fibers provides a promising application for corresponding material as a bactericidal agent for wound healing treatment.

[Research progress of articular cartilage scaffold for tissue engineering].

PubMed

Liu, Qingyu; Wang, Fuyou; Yang, Liu

2012-10-01

To review the research progress of articular cartilage scaffold materials and look into the future development prospects. Recent literature about articular cartilage scaffold for tissue engineering was reviewed, and the results from experiments and clinical application about natural and synthetic scaffold materials were analyzed. The design of articular cartilage scaffold for tissue engineering is vital to articular cartilage defects repair. The ideal scaffold can promote the progress of the cartilage repair, but the scaffold materials still have their limitations. It is necessary to pay more attention to the research of the articular cartilage scaffold, which is significant to the repair of cartilage defects in the future.

Near-Field Scanning Optical Microscopy of Soft, Biological, or Rough Objects in Aqueous Environment: Challenges and some Remedies to Circumvent

NASA Technical Reports Server (NTRS)

Vikram, C. S.; Witherow, W. K.

1999-01-01

Near-field scanning optical microscopy is an established technique for sub-wavelength spatial resolution in imaging, spectroscopy, material science, surface chemistry, polarimetry, etc. A significant amount of confidence has been established for thin hard specimens in air. However when soft, biological, rough, in aqueous environment object, or a combination is involved, the progress has been slow. The tip-sample mechanical interaction, heat effects to sample, drag effects to the probe, difficulty in controlling tip-sample separation in case of rough objects, light scattering from sample thickness, etc. create problems. Although these problems are not even fully understood, there have been attempts to study them with the aim of performing reliable operations. In this review we describe these attempts. Starting with general problems encountered, various effects like polarization, thermal, and media are covered. The roles of independent tip-sample distance control tools in the relevant situations are then described. Finally progress in fluid cell aspect has been summarized.

Functional and Biomimetic Materials for Engineering of the Three-Dimensional Cell Microenvironment.

PubMed

Huang, Guoyou; Li, Fei; Zhao, Xin; Ma, Yufei; Li, Yuhui; Lin, Min; Jin, Guorui; Lu, Tian Jian; Genin, Guy M; Xu, Feng

2017-10-25

The cell microenvironment has emerged as a key determinant of cell behavior and function in development, physiology, and pathophysiology. The extracellular matrix (ECM) within the cell microenvironment serves not only as a structural foundation for cells but also as a source of three-dimensional (3D) biochemical and biophysical cues that trigger and regulate cell behaviors. Increasing evidence suggests that the 3D character of the microenvironment is required for development of many critical cell responses observed in vivo, fueling a surge in the development of functional and biomimetic materials for engineering the 3D cell microenvironment. Progress in the design of such materials has improved control of cell behaviors in 3D and advanced the fields of tissue regeneration, in vitro tissue models, large-scale cell differentiation, immunotherapy, and gene therapy. However, the field is still in its infancy, and discoveries about the nature of cell-microenvironment interactions continue to overturn much early progress in the field. Key challenges continue to be dissecting the roles of chemistry, structure, mechanics, and electrophysiology in the cell microenvironment, and understanding and harnessing the roles of periodicity and drift in these factors. This review encapsulates where recent advances appear to leave the ever-shifting state of the art, and it highlights areas in which substantial potential and uncertainty remain.

Annual Reports Regarding Progress in Developing a Dredged Material Management Plan for the Long Island Sound Region

EPA Pesticide Factsheets

The site designation for the Western and Central Long Island Sound disposal sites requires the completion of a Dredged Material Management Plan (DMMP) and EPA to conduct an annual review of progress toward completion of the DMMP.

A Radiographic Comparison of Progressive and Conventional Loading on Crestal Bone Loss and Density in Single Dental Implants: A Randomized Controlled Trial Study

PubMed Central

Ghoveizi, Rahab; Alikhasi, Marzieh; Siadat, Mohammad-Reza; Siadat, Hakimeh; Sorouri, Majid

2013-01-01

Objective: Crestal bone loss is a biological complication in implant dentistry. The aim of this study was to compare the effect of progressive and conventional loading on crestal bone height and bone density around single osseointegrated implants in the posterior maxilla by a longitudinal radiographic assessment technique. Materials and Methods: Twenty micro thread implants were placed in 10 patients (two implants per patient). One of the two implants in each patient was assigned to progressive and the other to conventional loading groups. Eight weeks after surgery, conventional implants were restored with a metal ceramic crown and the progressive group underwent a progressive loading protocol. The progressive loading group took different temporary acrylic crowns at 2, 4 and 6 months. After eight months, acrylic crowns were replaced with a metal ceramic crown. Computer radiography of both progressive and conventional implants was taken at 2, 4, 6, and 12 months. Image analysis was performed to measure the height of crestal bone loss and bone density. Results: The mean values of crestal bone loss at month 12 were 0.11 (0.19) mm for progressively and 0.36 (0.36) mm for conventionally loaded implants, with a statistically significant difference (P < 0.05) using Wilcoxon sign rank. Progressively loaded group showed a trend for higher bone density gain compared to the conventionally loaded group, but when tested with repeated measure ANOVA, the differences were not statistically significant (P > 0.05). Conclusion: The progressive group showed less crestal bone loss in single osseointegrated implant than the conventional group. Bone density around progressively loaded implants showed increase in crestal, middle and apical areas. PMID:23724215

Evaluating progressive-rendering algorithms in appearance design tasks.

PubMed

Jiawei Ou; Karlik, Ondrej; Křivánek, Jaroslav; Pellacini, Fabio

2013-01-01

Progressive rendering is becoming a popular alternative to precomputational approaches to appearance design. However, progressive algorithms create images exhibiting visual artifacts at early stages. A user study investigated these artifacts' effects on user performance in appearance design tasks. Novice and expert subjects performed lighting and material editing tasks with four algorithms: random path tracing, quasirandom path tracing, progressive photon mapping, and virtual-point-light rendering. Both the novices and experts strongly preferred path tracing to progressive photon mapping and virtual-point-light rendering. None of the participants preferred random path tracing to quasirandom path tracing or vice versa; the same situation held between progressive photon mapping and virtual-point-light rendering. The user workflow didn’t differ significantly with the four algorithms. The Web Extras include a video showing how four progressive-rendering algorithms converged (at http://youtu.be/ck-Gevl1e9s), the source code used, and other supplementary materials.

Self-organization in precipitation reactions far from the equilibrium

PubMed Central

Nakouzi, Elias; Steinbock, Oliver

2016-01-01

Far from the thermodynamic equilibrium, many precipitation reactions create complex product structures with fascinating features caused by their unusual origins. Unlike the dissipative patterns in other self-organizing reactions, these features can be permanent, suggesting potential applications in materials science and engineering. We review four distinct classes of precipitation reactions, describe similarities and differences, and discuss related challenges for theoretical studies. These classes are hollow micro- and macrotubes in chemical gardens, polycrystalline silica carbonate aggregates (biomorphs), Liesegang bands, and propagating precipitation-dissolution fronts. In many cases, these systems show intricate structural hierarchies that span from the nanometer scale into the macroscopic world. We summarize recent experimental progress that often involves growth under tightly regulated conditions by means of wet stamping, holographic heating, and controlled electric, magnetic, or pH perturbations. In this research field, progress requires mechanistic insights that cannot be derived from experiments alone. We discuss how mesoscopic aspects of the product structures can be modeled by reaction-transport equations and suggest important targets for future studies that should also include materials features at the nanoscale. PMID:27551688

Controlling Emergent Ferromagnetism at Complex Oxide Interfaces

NASA Astrophysics Data System (ADS)

Grutter, Alexander

The emergence of complex magnetic ground states at ABO3 perovskite heterostructure interfaces is among the most promising routes towards highly tunable nanoscale materials for spintronic device applications. Despite recent progress, isolating and controlling the underlying mechanisms behind these emergent properties remains a highly challenging materials physics problems. In particular, generating and tuning ferromagnetism localized at the interface of two non-ferromagnetic materials is of fundamental and technological interest. An ideal model system in which to study such effects is the CaRuO3/CaMnO3 interface, where the constituent materials are paramagnetic and antiferromagnetic in the bulk, respectively. Due to small fractional charge transfer to the CaMnO3 (0.07 e-/Mn) from the CaRuO3, the interfacial Mn ions are in a canted antiferromagnetic state. The delicate balance between antiferromagnetic superexchange and ferromagnetic double exchange results in a magnetic ground state which is extremely sensitive to perturbations. We exploit this sensitivity to achieve control of the magnetic interface, tipping the balance between ferromagnetic and antiferromagnetic interactions through octahedral connectivity modification. Such connectivity effects are typically tightly confined to interfaces, but by targeting a purely interfacial emergent magnetic system, we achieve drastic alterations to the magnetic ground state. These results demonstrate the extreme sensitivity of the magnetic state to the magnitude of the charge transfer, suggesting the potential for direct electric field control. We achieve such electric field control through direct back gating of a CaRuO3/CaMnO3 bilayer. Thus, the CaRuO3/CaMnO3 system provides new insight into how charge transfer, interfacial symmetry, and electric fields may be used to control ferromagnetism at the atomic scale.

Methods for the isolation and identification of polycyclic aromatic hydrocarbons found in complex mixtures and the determination of their possible toxicity by means of bioassay techniques. Progress report, August 1, 1978-August 1979

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

Lipsky, S.R.; McMurray, W.J.

1979-08-01

After electronic instrument difficulties, a computer controlled gas chromatography-mass spectrometer has been delivered, installed and is operational. Data gathering is commencing from adipose tissue obtained by needle biopsy. Materials under consideration include shale oil extracts, their dimethyl sulfoxide extracts and product waters. A chart of individual identified PAH's is given. (PCS)

5m RPV for Exploring Joined Wing Gust Response

DTIC Science & Technology

2009-12-01

an outer layer of light glass scrim used as the first layer. Varying layers of carbon cloth are used and then the core material is added. In this...for various angles of attack and sideslip angles. A parametric model is developed using Phoenix Integration’s Model Center Software (MC). This model...by the ground control software and finally a piece of real-time footage taken from the on-board, gimbaled camera. 2009 Progress Report 27

Fusion materials semiannual progress report for the period ending June 30, 1998

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

Burn, G.

1998-09-01

This is the twenty-fourth in a series of semiannual technical progress reports on fusion materials. This report combines the full spectrum of research and development activities on both metallic and non-metallic materials with primary emphasis on the effects of the neutronic and chemical environment on the properties and performance of materials for in-vessel components. This effort forms one element of the materials program being conducted in support of the Fusion Energy Sciences Program of the US Department of Energy. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

Advanced refractory-metal and process technology for the fabrication of x-ray masks

NASA Astrophysics Data System (ADS)

Brooks, Cameron J.; Racette, Kenneth C.; Lercel, Michael J.; Powers, Lynn A.; Benoit, Douglas E.

1999-06-01

This paper provides an in-depth report of the advanced materials and process technology being developed for x-ray mask manufacturing at IBM. Masks using diamond membranes as replacement for silicon carbide are currently being fabricated. Alternate tantalum-based absorbers, such as tantalum boron, which offer improved etch resolution and critical dimension control, as well as higher x-ray absorption, are also being investigated. In addition to the absorber studies, the development of conductive chromium- based hard-mask films to replace the current silicon oxynitride layer is being explored. The progress of this advanced-materials work, which includes significant enhancements to x-ray mask image-placement performance, will be outlined.

On firework blasts and qualitative parameter dependency.

PubMed

Zohdi, T I

2016-01-01

In this paper, a mathematical model is developed to qualitatively simulate the progressive time-evolution of a blast from a simple firework. Estimates are made for the blast radius that one can expect for a given amount of detonation energy and pyrotechnic display material. The model balances the released energy from the initial blast pulse with the subsequent kinetic energy and then computes the trajectory of the material under the influence of the drag from the surrounding air, gravity and possible buoyancy. Under certain simplifying assumptions, the model can be solved for analytically. The solution serves as a guide to identifying key parameters that control the evolving blast envelope. Three-dimensional examples are given.

On firework blasts and qualitative parameter dependency

PubMed Central

Zohdi, T. I.

2016-01-01

In this paper, a mathematical model is developed to qualitatively simulate the progressive time-evolution of a blast from a simple firework. Estimates are made for the blast radius that one can expect for a given amount of detonation energy and pyrotechnic display material. The model balances the released energy from the initial blast pulse with the subsequent kinetic energy and then computes the trajectory of the material under the influence of the drag from the surrounding air, gravity and possible buoyancy. Under certain simplifying assumptions, the model can be solved for analytically. The solution serves as a guide to identifying key parameters that control the evolving blast envelope. Three-dimensional examples are given. PMID:26997903

On the physics of the emergence of sensorimotor control in the absence of the brain.

PubMed

Matsuno, Koichiro

2015-12-01

The evolutionary origin of sensorimotor control requires a sort of physical durability, other than Galilean inertia being accessible in third-person description in the present tense. One candidate to address this need is the 'class property' of a material body's durability remaining invariant during the exchange of component elements. Using grammatical tense as a descriptive attribute, this durability is accessible only in the frequent update of the present perfect tense in the present progressive tense at the 'now' of the present moment. In this view, the update of the perfect tense is equated with the onset and occurrence of on/off switching behavior of physical origin underlying the phenomena of sensorimotor control. Notably, the physical update of the perfect tense is specific only to the 'now and here' that is central in the tradition of phenomenology. The phenomena upholding thermodynamics, when taken apart from its theory, are decisive in facilitating the onset of sensorimotor control. Instrumental to the emergence of both life in general and sensorimotor control in particular may be the occurrence of a 'physical and chemical affinity' of the material bodies of whatever type. Such will let the constant exchange of component elements be feasible, so that the class identity equipped with the capacity for measurement is made available within the phenomenon. Material bodies constantly exchanging such component elements would make the material world open to biology by allowing each element to experience the organizational whole from within. The internal observer responsible for the origins of life may do double duty of letting itself be durable on the material basis while observing the conditions making it durable on the linguistic ground. The origins of life appear to us a material phenomenon when they are approached with use of our linguistic tools that can get rid of the strict stipulation of an abstract nature applied to the description of dynamical laws in physics. Copyright © 2015. Published by Elsevier Ltd.

JOYO-1 Irradiation Test Campaign Technical Close-out, For Information

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

G. Borges

2006-01-31

The JOYO-1 irradiation testing was designed to screen the irradiation performance of candidate cladding, structural and reflector materials in support of space reactor development. The JOYO-1 designation refers to the first of four planned irradiation tests in the JOYO reactor. Limited irradiated material performance data for the candidate materials exists for the expected Prometheus-1 duration, fluences and temperatures. Materials of interest include fuel element cladding and core materials (refractory metal alloys and silicon carbide (Sic)), vessel and plant structural materials (refractory metal alloys and nickel-base superalloys), and control and reflector materials (BeO). Key issues to be evaluated were long termmore » microstructure and material property stability. The JOYO-1 test campaign was initiated to irradiate a matrix of specimens at prototypical temperatures and fluences anticipated for the Prometheus-1 reactor [Reference (1)]. Enclosures 1 through 9 describe the specimen and temperature monitors/dosimetry fabrication efforts, capsule design, disposition of structural material irradiation rigs, and plans for post-irradiation examination. These enclosures provide a detailed overview of Naval Reactors Prime Contractor Team (NRPCT) progress in specific areas; however, efforts were in various states of completion at the termination of NRPCT involvement with and restructuring of Project Prometheus.« less

U.S. Department of Energy physical protection upgrades at the Latvian Academy of Sciences Nuclear Research Center, Latvia

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

Haase, M.; Hine, C.; Robertson, C.

1996-12-31

Approximately five years ago, the Safe, Secure Dismantlement program was started between the US and countries of the Former Soviet Union (FSU). The purpose of the program is to accelerate progress toward reducing the risk of nuclear weapons proliferation, including such threats as theft, diversion, and unauthorized possession of nuclear materials. This would be accomplished by strengthening the material protection, control, and accounting systems within the FSU countries. Under the US Department of Energy`s program of providing cooperative assistance to the FSU countries in the areas of Material Protection, Control, and Accounting (MPC and A), the Latvian Academy of Sciencesmore » Nuclear Research Center (LNRC) near Riga, Latvia, was identified as a candidate site for a cooperative MPC and A project. The LNRC is the site of a 5-megawatt IRT-C pool-type research reactor. This paper describes: the process involved, from initial contracting to project completion, for the physical protection upgrades now in place at the LNRC; the intervening activities; and a brief overview of the technical aspects of the upgrades.« less

Recent Advances in Multi-component Particles Assembly.

PubMed

Guo, Dan; Song, Yanlin

2018-03-09

Particles assembly and co-assembly have been research frontiers in chemistry and material science in the past few decades. To achieve a large variety of intricate structures and functional materials, remarkable progress has been made in the particle assembly principles and strategies. It can be summarized that the particle assembly is driven by intrinsic interparticle interaction or the external control. In this article, we focus on binary or ternary particles co-assembly and review the principles and feasible strategies. These advances have led to new disciplines of microfabrication technology and material engineering. Although remarked achievement on particle-based structures has been made, it is still challenging to fully develop general and facile strategies to precisely control the one-dimensional (1D) co-assembly. This article reviews the recent development on multi-component particles co-assembly, which significantly increases structural complexity and functional diversity. In particular, we highlight the advances in the particles co-assembly of well-ordered 1D binary superstructures by liquid soft confinement. Finally, prospective outlook for future trends in this field is proposed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

NASA Applications of Molecular Adsorber Coatings

NASA Technical Reports Server (NTRS)

Abraham, Nithin S.

2015-01-01

The Molecular Adsorber Coating (MAC) is a new, innovative technology that was developed to reduce the risk of molecular contamination on spaceflight applications. Outgassing from materials, such as plastics, adhesives, lubricants, silicones, epoxies, and potting compounds, pose a significant threat to the spacecraft and the lifetime of missions. As a coating made of highly porous inorganic materials, MAC offers impressive adsorptive capabilities that help capture and trap contaminants. Past research efforts have demonstrated the coating's promising adhesion performance, optical properties, acoustic durability, and thermal stability. These results advocate its use near or on surfaces that are targeted by outgassed materials, such as internal optics, electronics, detectors, baffles, sensitive instruments, thermal control coatings, and vacuum chamber test environments. The MAC technology has significantly progressed in development over the recent years. This presentation summarizes the many NASA spaceflight applications of MAC and how the coatings technology has been integrated as a mitigation tool for outgassed contaminants. For example, this sprayable paint technology has been beneficial for use in various vacuum chambers for contamination control and hardware bake-outs. The coating has also been used in small instrument cavities within spaceflight instrument for NASA missions.

Towards tunable and multifunctional interfaces: Multicomponent amorphous alloys and bilayer stacks

NASA Astrophysics Data System (ADS)

Kast, Matthew G.

Controlling the electronic structure and requisite charge transfer at and across interfaces is a grand challenge of materials science. Despite decades of research and numerous successes in the fields microelectronics and photovoltaics much work remains to be done. In many applications, whether they be in microelectronics, photovoltaics or display technology there is a demand for multiple functions at a single interface. Historically, existent materials were either discarded as an option due to known properties or tested with some application based figure of merit in mind. Following this, the quality of the material and/or the preparation of the surface/interface to which the material would be deposited was optimized. As the microelectronics and photovoltaics industries have matured, continued progress (faster, lower power transistors and more efficient, cheaper, abundant solar cells) will require new materials (possibly not previously existent) that are fundamentally better for their application than their highly optimized existent counter parts. The manifestation of this has been seen in the microelectronics field with introduction of hafnium silicates to replace silica (which had previously been monumentally successful) as the gate dielectrics for the most advanced transistors. Continued progress in efficient, cheap, abundant photovoltaics will require similar advances. Advances will be needed in the area of new abundant absorbers that can be deposited cheaply which result in materials with high efficiencies. In addition, selective contacts capable of extracting charge from efficient absorbers with low ohmic losses and low recombination rates will be needed. Presented here are two approaches to the multifunctional interface problem, first the use of amorphous alloys that open up the accessible composition space of thin films significantly and second the use of bilayers that loosen the requirements of a single film at an interface.

Time-frequency analysis of acoustic emission signals generated by the Glass Fibre Reinforced Polymer Composites during the tensile test

NASA Astrophysics Data System (ADS)

Świt, G.; Adamczak, A.; Krampikowska, A.

2017-10-01

Fibre reinforced polymer composites are currently dominating in the composite materials market. The lack of detailed knowledge about their properties and behaviour in various conditions of exposure under load significantly limits the broad possibilities of application of these materials. Occurring and accumulation of defects in material during the exploitation of the construction lead to the changes of its technical condition. The necessity to control the condition of the composite is therefore justified. For this purpose, non-destructive method of acoustic emission can be applied. This article presents an example of application of acoustic emission method based on time analysis and time-frequency analysis for the evaluation of the progress of the destructive processes and the level of degradation of glass fibre reinforced composite tapes that were subject to tensile testing.

Metallurgical Research Relating to the Development of Metals and Alloys for Use in the High-Temperature Components of Jet-Engines, Gas Turbines and Other Aircraft Propulsion Systems

NASA Technical Reports Server (NTRS)

1948-01-01

Considerable work has been done on report preparation. All items listed in the March program report will be reported during July. Fundamental studies are in progress to establish the fundamental processes by which treatments and composition control properties of commercial alloys at high temperatures. As yet work has been confined to Low-Carbon N155 alloy and progress has been reported twice previously. The work is divided into two sections: studies of solution treated and aged material and studies of rolled structures. Electron microscopic work has been started as an additional technique for the studies. Brief descriptions of experimental techniques used, results, and interpretation of the data obtained since the last report covering this field are summarized below. Since the work outlined is to a large extent still in progress, the discussion given is to be considered tentative and subject to further modification as additional data becomes available.

GAK, a regulator of clathrin-mediated membrane traffic, also controls centrosome integrity and chromosome congression.

PubMed

Shimizu, Hiroyuki; Nagamori, Ippei; Yabuta, Norikazu; Nojima, Hiroshi

2009-09-01

Cyclin G-associated kinase (GAK) is an association partner of clathrin heavy chain (CHC) and is essential for clathrin-mediated membrane trafficking. Here, we report two novel functions of GAK: maintenance of proper centrosome maturation and of mitotic chromosome congression. Indeed, GAK knockdown by siRNA caused cell-cycle arrest at metaphase, which indicates that GAK is required for proper mitotic progression. We found that this impaired mitotic progression was due to activation of the spindle-assembly checkpoint, which senses protruded, misaligned or abnormally condensed chromosomes in GAK-siRNA-treated cells. GAK knockdown also caused multi-aster formation, which was due to abnormal fragmentation of pericentriolar material, but not of the centrioles. Moreover, GAK and CHC cooperated in the same pathway and interacted in mitosis to regulate the formation of a functional spindle. Taken together, we conclude that GAK and clathrin function cooperatively not only in endocytosis, but also in mitotic progression.

Effect of Adventitious Carbon on the Environmental Degradation of SiC/BN/SiC Composites

NASA Technical Reports Server (NTRS)

Ogbuji, L. U. J. T.; Yun, H. M.; DiCarlo, J.

2002-01-01

Pesting remains a major obstacle to the application of SiC/SiC composites in engine service and selective degradation of the boron nitride interphase at intermediate temperatures is of primary concern. However, significant progress has been made on interphase improvement recently and we now know more about the phenomenon and ways to suppress it. By screening SiC/BN/SiC materials through characterization of strength and microstructures after exposure in a burner rig, some factors that control pesting in these composites have been determined. A key precaution is careful control of elemental carbon presence in the interphase region.

Radiation Therapy for Pilocytic Astrocytomas of Childhood

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

Mansur, David B., E-mail: mansur@radonc.wustl.ed; Rubin, Joshua B.; Kidd, Elizabeth A.

Purpose: Though radiation therapy is generally considered the most effective treatment for unresectable pilocytic astrocytomas in children, there are few data to support this claim. To examine the efficacy of radiation therapy for pediatric pilocytic astrocytomas, we retrospectively reviewed the experience at our institution. Methods and Materials: Thirty-five patients 18 years old or younger with unresectable tumors and without evidence of neurofibromatosis have been treated since 1982. Patients were treated with local radiation fields to a median dose of 54 Gy. Six patients were treated with radiosurgery to a median dose of 15.5 Gy. Five patients were treated with initialmore » chemotherapy and irradiated after progression. Results: All patients were alive after a median follow-up of 5.0 years. However, progression-free survival was 68.7%. None of 11 infratentorial tumors progressed compared with 6 of 20 supratentorial tumors. A trend toward improved progression-free survival was seen with radiosurgery (80%) compared with external beam alone (66%), but this difference did not reach statistical significance. Eight of the 9 patients progressing after therapy did so within the irradiated volume. Conclusions: Although the survival of these children is excellent, almost one third of patients have progressive disease after definitive radiotherapy. Improvements in tumor control are needed in this patient population, and the optimal therapy has not been fully defined. Prospective trials comparing initial chemotherapy to radiation therapy are warranted.« less

Analysis of GMO Plum Plant Culture in System Operations Failure

NASA Technical Reports Server (NTRS)

Mercado, Dianne

2017-01-01

GMO plum trees are being evaluated at the Kennedy Space Center as a possible candidate for future space crops. Previously conducted horticultural testing compared the performance of several plum genotypes in controlled environment chambers, resulting in a down-selection to the NASA-11 genotype. Precursory studies determined the water use requirements to sustain the plants as well as the feasibility of grafting non-GMO plum scions onto GMO plum rootstocks of NASA-5, NASA-10, and NASA-11 genotypes. This study follows the growth and horticultural progress of plum trees and in-vitro cultures from August 2017 to November 2017, and provides supplemental support for future GMO plum studies. The presence of Hurricane Irma in early September 2017 resulted in the plants undergoing material deterioration from major changes to their overall horticultural progress.

How accelerated biological aging can affect solar reflective polymeric based building materials

NASA Astrophysics Data System (ADS)

Ferrari, C.; Santunione, G.; Libbra, A.; Muscio, A.; Sgarbi, E.

2017-11-01

Among the main issues concerning building materials, in particular outdoor ones, one can identify the colonization by microorganisms referred to as biological aggression. This can affect not only the aesthetical aspect but also the thermal performance of solar reflective materials. In order to improve the reliability of tests aimed to assess the resistance to biological aggression and contextually reduce the test duration, an accelerated test method has been developed. It is based on a lab reproducible setup where specific and controlled environmental and boundary conditions are imposed to accelerate as much as possible biological growth on building materials. Due to their widespread use, polymeric materials have been selected for the present analysis, in the aim of reaching an advanced bio-aged level in a relatively short time (8 weeks or less) and at the same time comparatively evaluate different materials under a given set of ageing conditions. Surface properties before, during and after ageing have been investigated by surface, microstructural and chemical analyses, as well as by examination of time progressive images to assess bacterial and algal growth rate.

Fusion Materials Semiannual Progress Report for Period Ending December 31, 1998

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

Rowcliff, A.F.; Burn, G.

1999-04-01

This is the twenty-fifth in a series of semiannual technical progress reports on fusion materials. This report combines the full spectrum of research and development activities on both metallic and non-metallic materials with primary emphasis on the effects of the neutronic and chemical environment on the properties and performance of materials for in-vessel components. This effort forms one element of the materials program being conducted in support of the Fusion Energy Sciences Program of the U.S. Department of Energy. The other major element of the program is concerned with the interactions between reactor materials and the plasma and is reportedmore » separately.« less

Thermostructural responses of carbon phenolics in a restrained thermal growth test

NASA Technical Reports Server (NTRS)

Wang, C. Jeff

1992-01-01

The thermostructural response of carbon phenolic components in a solid rocket motor (SRM) is a complex process. It involves simultaneous heat and mass transfer along with chemical reactions in a multiphase system with time-dependent material properties and boundary conditions. In contrast to metals, the fracture of fiber-reinforced composites is characterized by the initiation and progression of multiple failures of different modes such as matrix cracks, interfacial debonding, fiber breaks, and delamination. The investigation of thermostructural responses of SRM carbon phenolics is further complicated by different failure modes under static and dynamic load applications. Historically, there have been several types of post-firing anomalies found in the carbon phenolic composites of the Space Shuttle SRM nozzle. Three major failure modes which have been observed on SRM nozzles are pocketing (spallation), ply-lift, and wedge-out. In order to efficiently control these anomalous phenomena, an investigation of fracture mechanisms under NASA/MSFC RSRM (Redesigned Solid Rocket Motor) and SPIP (Solid Propulsion Integrity Program) programs have been conducted following each anomaly. This report reviews the current progress in understanding the effects of the thermostructural behavior of carbon phenolics on the failure mechanisms of the SRM nozzle. A literature search was conducted and a technical bibliography was developed to support consolidation and assimilation of learning from the RSRM and SPIP investigation efforts. Another important objective of this report is to present a knowledge-based design basis for carbon phenolics that combines the analyses of thermochemical decomposition, pore pressure stresses, and thermostructural properties. Possible areas of application of the knowledge-based design include critical material properties development, nozzle component design, and SRM materials control.

Strategies for Directing the Structure and Function of 3D Collagen Biomaterials across Length Scales

PubMed Central

Walters, Brandan D.; Stegemann, Jan P.

2013-01-01

Collagen type I is a widely used natural biomaterial that has found utility in a variety of biological and medical applications. Its well characterized structure and role as an extracellular matrix protein make it a highly relevant material for controlling cell function and mimicking tissue properties. Collagen type I is abundant in a number of tissues, and can be isolated as a purified protein. This review focuses on hydrogel biomaterials made by reconstituting collagen type I from a solubilized form, with an emphasis on in vitro studies in which collagen structure can be controlled. The hierarchical structure of collagen from the nanoscale to the macroscale is described, with an emphasis on how structure is related to function across scales. Methods of reconstituting collagen into hydrogel materials are presented, including molding of macroscopic constructs, creation of microscale modules, and electrospinning of nanoscale fibers. The modification of collagen biomaterials to achieve desired structures and functions is also addressed, with particular emphasis on mechanical control of collagen structure, creation of collagen composite materials, and crosslinking of collagenous matrices. Biomaterials scientists have made remarkable progress in rationally designing collagen-based biomaterials and in applying them to both the study of biology and for therapeutic benefit. This broad review illustrates recent examples of techniques used to control collagen structure, and to thereby direct its biological and mechanical functions. PMID:24012608

Progress in nanotechnology for healthcare.

PubMed

Raffa, V; Vittorio, O; Riggio, C; Cuschieri, A

2010-06-01

This review based on the Wickham lecture given by AC at the 2009 SMIT meeting in Sinaia outlines the progress made in nano-technology for healthcare. It describes in brief the nature of nano-materials and their unique properties which accounts for the significant research both in scientific institutions and industry for translation into new therapies embodied in the emerging field of nano-medicine. It stresses that the potential of nano-medicine to make significant inroads for more effective therapies both for life-threatening and life-disabling disorders will only be achieved by high-quality life science research. The first generation of passive nano-diagnostics based on nanoparticle contrast agents for magnetic resonance imaging is well established in clinical practice and new such contrast agents are undergoing early clinical evaluation. Likewise active (second generation) nano-therapies, exemplified by targeted control drug release systems are undergoing early clinical evaluation. The situation concerning other nano-materials such as carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs) is less advanced although considerable progress has been made on their coating for aqueous dispersion and functionalisation to enable carriage of drugs, genes and fluorescent markers. The main problem related to the clinical use of these nanotubes is that there is no consent among scientists on the fate of such nano-materials following injection or implantation in humans. Provided carbon nanotubes are manufactured to certain medical criteria (length around 1 mum, purity of 97-99% and low Fe content) they exhibit no cytotoxicity on cell cultures and demonstrate full bio-compatibility on in vivo animal studies. The results of recent experimental studies have demonstrated the potential of technologies based on CNTs for low voltage wireless electro-chemotherapy of tumours and for electro-stimulation therapies for cardiac, neurodegenerative and skeletal and visceral muscle disorders.

Interactions between biomaterials and the sclera: Implications on myopia progression

NASA Astrophysics Data System (ADS)

Su, James

Myopia prevalence has steadily climbed worldwide in recent decades with the most dramatic impact in East Asian countries. Treatments such as eyeglasses, contact lenses, and laser surgery for the refractive error are widely available, but none cures the underlying cause. In progressive high myopia, invasive surgical procedures using a scleral buckle for mechanical support are performed since the patient is at risk of becoming blind. The treatment outcome is highly dependent on the surgeon's skills and the patient's myopia progression rate, with limited choices in buckling materials. This dissertation, in four main studies, represents efforts made to control high myopia progression through the exploration and development of biomaterials that influence scleral growth. First, mRNA expression levels of the chick scleral matrix metalloproteinases, tissue-inhibitor of matrix metalloproteinases, and transforming growth factor-beta 2 were assessed for temporal and defocus power effects. The first study elucidated the roles that these factors play in scleral growth regulation and suggested potential motifs that can be incorporated in future biomaterials design. Second, poly(vinyl-pyrrolidone) as injectable gels and poly(2-hydroxyethyl methacrylate) as solid strips were implanted in chicks to demonstrate the concept of posterior pole scleral reinforcements. This second study found that placing appropriate biomaterials at the posterior pole of the eye could directly influence scleral remodeling by interacting with the host cells. Both studies advanced the idea that scleral tissue remodeling could be potentially controlled by well-designed biomaterials. These findings led to the exploration of biomimetic hydrogels comprising enzymatically-degradable semi-interpenetrating polymer networks (edsIPNs) to determine their biocompatibility and effects on the chick posterior eye wall. This third study demonstrated the feasibility of stimulating scleral growth by applying biomimetic injectable materials. Fourth, the muscarinic antagonist drug, atropine, was encapsulated within the edsIPNs and delivered to the chick eye posterior pole to evaluate the local effect of atropine release. This fourth study offered an alternative method of ocular drug delivery for treatment of myopia, with the potential to elucidate the actual location of the inhibitive effect of atropine on myopia progression. In summary, this dissertation contributes to the design and use of biomaterials specific to myopia therapy and adds novel insights to scleral tissue engineering.

Reduced graphene oxide-ZnO composites based gas sensors: A review

NASA Astrophysics Data System (ADS)

Thakare, N. B.; Raghuwanshi, F. C.; Kalyamwar, V. S.; Tamgadge, Y. S.

2018-05-01

The need to monitor and control life threatening gases has led to research and development of a wide variety of sensors using different materials and technologies. Recently rGO (reduced graphene oxide)-MOS (Metal Oxide Semiconductor) architectures have been studied for efficient and cost effective gas sensors that will operate at low temperature. In this review paper, we review latest findings and progress in rGO-ZnO composites as sensors to detect volatile and toxic gases.

Magnetic and Optical Properties of Submicron-Size Hollow Spheres

PubMed Central

Ye, Quan-Lin; Yoshikawa, Hirofumi; Awaga, Kunio

2010-01-01

Magnetic hollow spheres with a controlled diameter and shell thickness have emerged as an important class of magnetic nanomaterials. The confined hollow geometry and pronouncedly curved surfaces induce unique physical properties different from those of flat thin films and solid counterparts. In this paper, we focus on recent progress on submicron-size spherical hollow magnets (e.g., cobalt- and iron-based materials), and discuss the effects of the hollow shape and the submicron size on magnetic and optical properties.

Radar Cross Section Studies/Compact Range Research

NASA Technical Reports Server (NTRS)

Burnside, W. D.; Dominek, A. K.; Gupta, I. J.; Newman, E. H.; Pathak, P. H.; Peters, L., Jr.

1988-01-01

A summary is given of the achievements of NASA Grant NsG-1613 by Ohio State University from May 1, 1987 to April 30, 1988. The major topics covered are as follows: (1) electromagnetic scattering analysis; (2) indoor scattering measurement systems; (3) RCS control; (4) waveform processing techniques; (5) material scattering and design studies; (6) design and evaluation of design studies; and (7) antenna studies. Major progress has been made in each of these areas as verified by the numerous publications produced.

Lawrence Livermore National Laboratory safeguards and security quarterly progress report to the US Department of Energy quarter ending September 30, 1994

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

Davis, G.; Mansur, D.L.; Ruhter, W.D.

1994-10-01

This report presents the details of the Lawrence Livermore National Laboratory safeguards and securities program. This program is focused on developing new technology, such as x- and gamma-ray spectrometry, for measurement of special nuclear materials. This program supports the Office of Safeguards and Securities in the following five areas; safeguards technology, safeguards and decision support, computer security, automated physical security, and automated visitor access control systems.

Outcomes and Control Rates for I-125 Plaque Brachytherapy for Uveal Melanoma: A Community-Based Institutional Experience

PubMed Central

Cook, Taylor

2014-01-01

Purpose. To evaluate our community-based institutional experience with plaque brachytherapy for uveal melanomas with a focus on local control rates, factors impacting disease progression, and dosimetric parameters impacting treatment toxicity. Methods and Materials. Our institution was retrospectively reviewed from 1996 to 2011; all patients who underwent plaque brachytherapy for uveal melanoma were included. Follow-up data were collected regarding local control, distant metastases, and side effects from treatment. Analysis was performed on factors impacting treatment outcomes and treatment toxicity. Results. A total of 107 patients underwent plaque brachytherapy, of which 88 had follow-up data available. Local control at 10 years was 94%. Freedom from progression (FFP) and overall survival at 10 years were 83% and 79%, respectively. On univariate analysis, there were no tumor or dosimetric treatment characteristics that were found to have a prognostic impact on FFP. Brachytherapy treatment was well tolerated, with clinically useful vision (>20/200) maintained in 64% of patients. Statistically significant dosimetric relationships were established with cataract, glaucoma, and retinopathy development (greatest P = 0.05). Conclusions. Treatment with plaque brachytherapy demonstrates excellent outcomes in a community-based setting. It is well tolerated and should remain a standard of care for COMS medium sized tumors. PMID:24734198

Reproductive History and Hormonal Birth Control Use Are Associated with Coronary Calcium Progression in Women with Type 1 Diabetes Mellitus

PubMed Central

Snell-Bergeon, Janet K.; Dabelea, Dana; Ogden, Lorraine G.; Hokanson, John E.; Kinney, Gregory L.; Ehrlich, James; Rewers, Marian

2008-01-01

Context: Coronary artery disease is increased in women with type 1 diabetes (T1D), compared with nondiabetic (Non-DM) women. Women with T1D have more menstrual dysfunction and are less likely to use hormonal birth control (BC) than Non-DM women. Objective: The purpose of this study was to determine whether coronary artery calcium (CAC) is associated with menstrual dysfunction and BC use in women with T1D. Materials and Methods: This was a prospective cohort study, and participants were followed up for an average of 2.4 yr. Patients: Patients included 612 women (293 T1D, 319 Non-DM) between the ages of 19 and 55 yr who had CAC measured twice by electron beam tomography. Results: Irregular menses and amenorrhea were more common in T1D than Non-DM women (22.1 vs. 14.9%, P < 0.05 and 16.6 vs. 7.0%, P < 0.001). T1D women reported less BC use than Non-DM women (79.8 vs. 89.9%, P < 0.001) and reached menarche at an older age (13.1 ± 1.8 vs. 12.8 ± 1.5 yr, P < 0.05). Use of BC was associated with less CAC progression in all women, but this association was stronger in T1D women (P value for interaction = 0.02). Irregular menses were associated with greater CAC progression only among T1D women. Conclusions: A prior history of BC use is associated with reduced CAC progression among all women, with a stronger association in T1D than in Non-DM women. Women with T1D who report irregular menses have increased CAC progression, compared with those with regular menses. PMID:18349069

A thermodynamic approach to nonlinear ultrasonics for material state awareness and prognosis

NASA Astrophysics Data System (ADS)

Chillara, Vamshi Krishna

2017-11-01

We develop a thermodynamic framework for modeling nonlinear ultrasonic damage sensing and prognosis in materials undergoing progressive damage. The framework is based on the internal variable approach and relies on the construction of a pseudo-elastic strain energy function that captures the energetics associated with the damage progression. The pseudo-elastic strain energy function is composed of two energy functions—one that describes how a material stores energy in an elastic fashion and the other describes how material dissipates energy or stores it in an inelastic fashion. Experimental motivation for the choice of the above two functionals is discussed and some specific choices pertaining to damage progression during fatigue and creep are presented. The thermodynamic framework is employed to model the nonlinear response of material undergoing stress relaxation and creep-like degradation. For each of the above cases, evolution of the nonlinearity parameter with damage as well as with macroscopic measurables like accumulated plastic strain is obtained.

DOE Energy Frontiers Research Center for Heterogeneous Functional Materials; the “HeteroFoaM Center”

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

Reifsnider, Kenneth Leonard

Synopsis of five year accomplishments: Devices that convert and store energy are generally made from heterogeneous constituent materials that act and interact to selectively conduct, transport, and separate mass, heat, and charge. Controlling these actions and interactions enables the technical breakthroughs that have made fuel cells, batteries, and solid state membranes, for example, essential parts of our society. In the biological sense, these materials are ‘vascular’ rather than primitive ‘cellular’ materials, in which the arrangements and configurations of the constituents (including their void phases) play essential and definitive roles in their functional capabilities. In 2009 a group of investigators, withmore » lifetime investments of effort in the understanding of heterogeneous materials, recognized that the design of such material systems is not an optimization problem as such. Local interactions of the constituents create “emergent” properties and responses that are not part of the formal set of constituent characteristics, in much the same sense that society and culture is created by the group interactions of the people involved. The design of emergent properties is an open question in all formal science, but for energy materials the lack of this foundation science relegates development tasks to Edisonian trial and error, with anecdotal success and frequent costly failures. That group defined, for the first time, multi-scale heterogeneous functional materials with functional disordered and void phase regions as “HeteroFoaM,” and formed the first multidisciplinary research team to define and codify the foundation science of that material class. The primary goal of the HeteroFoaM Center was, and is, to create and establish the multi-scale fundamental knowledge and related methodology required for the rational and systematic multiphysics design of heterogeneous functional materials and their interfaces and surfaces for applications in energy transformation and storage. The scope of the HeteroFoaM center was focused on the discovery and development of the control science of key phenomena across multiple length scales that create functionality in heterogeneous materials and their structured interfaces, boundaries, and surfaces for applications in energy technologies. The HeteroFoaM Center defined a critical path and established an essential foundation for progress in the field of heterogeneous functional materials. Perhaps the single most important element of progress was the establishment of the capability to design, characterize, and model heterogeneous functional materials at the conformal level, i.e., for a limited set of material systems, the HeteroFoaM team defined how to control the order / disorder at the atomic level, the surfaces, and the interfaces for selected constituent morphologies, and to use multiphysical models to explain the remarkable property variations resulting from that control science for several heterogeneous material systems. For those cases we defined “meso-structures” (at various scales) where the interactive physics of constituent phases acted to create emergent properties, e.g., strongly emergent mixed conductor behavior and ionic transport. The general approach used by this EFRC is shown in Fig. 1. The HeteroFoaM Center created the genre of Heterogeneous Functional Materials with functional surfaces and interfaces (including void phases) called HeteroFoaM as a science platform to enable rational analysis and design of functional material systems by focusing on the meso-interactions that drive emergent response. The team firmly established this approach with over 180 archival publications (see “Publications” section), 7 patent applications, and over 100 invited lectures in 15 countries on this topic, enabled by building a remarkably effective and uniquely coherent research team. Indeed, our team was our principal strength; this problem eluded solution earlier because such a team was not available.« less

Fluoride-Releasing Materials to Prevent White Spot Lesions around Orthodontic Brackets: A Systematic Review.

PubMed

Nascimento, Patrícia Layane de Menezes Macêdo; Fernandes, Micaelle Tenório Guedes; Figueiredo, Fabricio Eneas Diniz de; Faria-E-Silva, André Luis

2016-01-01

The relation between orthodontic fixed appliances use and enamel demineralization is well established. Different preventive approaches have been suggested to this problem, but controversy remains about which is the best. The aim of this study was to perform a systematic review of clinical trials that investigated the effectiveness of materials containing fluorides to lute brackets or cover the bonding interface in order to inhibit the development and progression of white spot lesions. The null hypothesis was that fluoride materials do not affect the incidence of white spot lesions around brackets. A MEDLINE search was conducted for randomized clinical trials evaluating the development of white spot lesions in patients using fixed orthodontic appliances, followed by meta-analysis comparing the results for patients for whom dental materials containing fluorides were used (experimental group) to those for whom these materials were not used (control group). The pooled relative risk of developing white spot lesions for the experimental group was 0.42 (95% confidence interval: 0.25 to 0.72); hence, when fluoride-releasing materials are used, the patient has 58% less risk of white spot lesion development. Regarding white spot lesion extent, the pooled mean difference between the experimental and control groups was not statistically significant (-0.12; 95% confidence interval: -0.29 to 0.04). In conclusion, the results of the present systematic review suggest that fluoride-releasing materials can reduce the risk of white spot lesions around brackets. However, when white spot lesions had already occurred, there is no evidence that fluoride-releasing materials reduce the extent of these lesions.

Templating Routes to Supported Oxide Catalysts by Design

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

Notestein, Justin M.

2016-09-08

The rational design and understanding of supported oxide catalysts requires at least three advancements, in order of increasing complexity: the ability to quantify the number and nature of active sites in a catalytic material, the ability to place external controls on the number and structure of these active sites, and the ability to assemble these active sites so as to carry out more complex functions in tandem. As part of an individual investigator research program that is integrated with the Northwestern University Institute for Catalysis in Energy Processes (ICEP) as of 2015, significant advances were achieved in these three areas.more » First, phosphonic acids were utilized in the quantitative assessment of the number of active and geometrically-available sites in MO x-SiO 2 catalysts, including nanocrystalline composites, co-condensed materials, and grafted structures, for M=Ti, Zr, Hf, Nb, and Ta. That work built off progress in understanding supported Fe, Cu, and Co oxide catalysts from chelating and/or multinuclear precursors to maximize surface reactivity. Secondly, significant progress was made in the new area of using thin oxide overcoats containing ‘nanocavities’ from organic templates as a method to control the dispersion and thermal stability of subsequently deposited metal nanoparticles or other catalytic domains. Similar methods were used to control surface reactivity in SiO 2-Al 2O 3 acid catalysts and to control reactant selectivity in Al 2O 3-TiO 2 photocatalysts. Finally, knowledge gained from the first two areas has been combined to synthesize a tandem catalyst for hydrotreating reactions and an orthogonal tandem catalyst system where two subsequent reactions in a reaction network are independently controlled by light and heat. Overall, work carried out under this project significantly advanced the knowledge of synthesis-structure-function relationships in supported oxide catalysts for energy applications.« less

Solution-processed organic thermoelectric materials exhibiting doping-concentration-dependent polarity.

PubMed

Hwang, Sunbin; Potscavage, William J; Yang, Yu Seok; Park, In Seob; Matsushima, Toshinori; Adachi, Chihaya

2016-10-26

Recent progress in conducting polymer-based organic thermoelectric generators (OTEGs) has resulted in high performance due to high Seebeck coefficient, high electrical conductivity (σ), and low thermal conductivity obtained by chemically controlling the materials's redox levels. In addition to improving the properties of individual OTEGs to obtain high performance, the development of solution processes for the fabrication of OTEG modules is necessary to realize large thermoelectric voltage and low-cost mass production. However, the scarcity of good candidates for soluble organic n-type materials limits the use of π-leg module structures consisting of complementary elements of p- and n-type materials because of unbalanced transport coefficients that lead to power losses. In particular, the extremely low σ of n-type materials compared with that of p-type materials is a serious challenge. In this study, poly(pyridinium phenylene) (P(PymPh)) was tested as an n-type semiconductor in solution-processed OTEGs, and the carrier density was controlled by a solution-based chemical doping process using the dopant sodium naphthalenide, a well-known reductant. The electronic structures and doping mechanism of P(PymPh) were explored based on the changes in UV-Vis-IR absorption, ultraviolet photoelectron, and X-ray photoelectron spectra. By controlling the dopant concentration, we demonstrate a maximum n-type power factor of 0.81 μW m -1 K -2 with high σ, and at higher doping concentrations, a switch from n-type to p-type TE operation. This is one of the first cases of a switch in polarity just by increasing the concentration of the reductant and may open a new route for simplified fabrication of complementary organic layers.

A Longitudinal Study of Junior High School Students' Conceptions of the Structure of Materials

ERIC Educational Resources Information Center

Margel, Hannah; Eylon, Bat-Sheva; Scherz, Zahava

2008-01-01

This longitudinal study investigated the progression in junior high school (JHS) students' conceptions of the structure of matter while studying a new instructional approach dealing with "Materials." In particular, we studied the progression of students' learning along two dimensions: (a) the conceptual model; and (b) the context of application.…

Recent progress of high performance polymer OLED and OPV materials for organic printed electronics.

PubMed

Sekine, Chizu; Tsubata, Yoshiaki; Yamada, Takeshi; Kitano, Makoto; Doi, Shuji

2014-06-01

The development of organic printed electronics has been expanding to a variety of applications and is expected to bring innovations to our future life. Along with this trend, high performance organic materials with cost-efficient fabrication processes and specific features such as thin, light weight, bendable, and low power consumption are required. A variety of organic materials have been investigated in the development of this field. The basic guidelines for material design and the recent progress of polymer-based organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs) are reported.

Recent progress of high performance polymer OLED and OPV materials for organic printed electronics

PubMed Central

Sekine, Chizu; Tsubata, Yoshiaki; Yamada, Takeshi; Kitano, Makoto; Doi, Shuji

2014-01-01

The development of organic printed electronics has been expanding to a variety of applications and is expected to bring innovations to our future life. Along with this trend, high performance organic materials with cost-efficient fabrication processes and specific features such as thin, light weight, bendable, and low power consumption are required. A variety of organic materials have been investigated in the development of this field. The basic guidelines for material design and the recent progress of polymer-based organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs) are reported. PMID:27877671

Age and Stress Prediction

NASA Technical Reports Server (NTRS)

2000-01-01

Genoa is a software product that predicts progressive aging and failure in a variety of materials. It is the result of a SBIR contract between the Glenn Research Center and Alpha Star Corporation. Genoa allows designers to determine if the materials they plan on applying to a structure are up to the task or if alternate materials should be considered. Genoa's two feature applications are its progressive failure simulations and its test verification. It allows for a reduction in inspection frequency, rapid design solutions, and manufacturing with low cost materials. It will benefit the aerospace, airline, and automotive industries, with future applications for other uses.

Solid-State Division progress report for period ending March 31, 1983

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

Green, P.H.; Watson, D.M.

1983-09-01

Progress and activities are reported on: theoretical solid-state physics (surfaces; electronic, vibrational, and magnetic properties; particle-solid interactions; laser annealing), surface and near-surface properties of solids (surface, plasma-material interactions, ion implantation and ion-beam mixing, pulsed-laser and thermal processing), defects in solids (radiation effects, fracture, impurities and defects, semiconductor physics and photovoltaic conversion), transport properties of solids (fast-ion conductors, superconductivity, mass and charge transport in materials), neutron scattering (small-angle scattering, lattice dynamics, magnetic properties, structure and instrumentation), and preparation and characterization of research materials (growth and preparative methods, nuclear waste forms, special materials). (DLC)

Recent progress of high performance polymer OLED and OPV materials for organic printed electronics

NASA Astrophysics Data System (ADS)

Sekine, Chizu; Tsubata, Yoshiaki; Yamada, Takeshi; Kitano, Makoto; Doi, Shuji

2014-06-01

The development of organic printed electronics has been expanding to a variety of applications and is expected to bring innovations to our future life. Along with this trend, high performance organic materials with cost-efficient fabrication processes and specific features such as thin, light weight, bendable, and low power consumption are required. A variety of organic materials have been investigated in the development of this field. The basic guidelines for material design and the recent progress of polymer-based organic light-emitting diodes (OLEDs) and organic photovoltaic cells (OPVs) are reported.

Application of Nanostructures in Electrochromic Materials and Devices: Recent Progress.

PubMed

Wang, Jin Min; Sun, Xiao Wei; Jiao, Zhihui

2010-11-26

The recent progress in application of nanostructures in electrochromic materials and devices is reviewed. ZnO nanowire array modified by viologen and WO₃, crystalline WO₃ nanoparticles and nanorods, mesoporous WO₃ and TiO₂, poly(3,4-ethylenedioxythiophene) nanotubes, Prussian blue nanoinks and nanostructures in switchable mirrors are reviewed. The electrochromic properties were significantly enhanced by applying nanostructures, resulting in faster switching responses, higher stability and higher optical contrast. A perspective on the development trends in electrochromic materials and devices is also proposed.

Solar energy conversion with photon-enhanced thermionic emission

NASA Astrophysics Data System (ADS)

Kribus, Abraham; Segev, Gideon

2016-07-01

Photon-enhanced thermionic emission (PETE) converts sunlight to electricity with the combined photonic and thermal excitation of charge carriers in a semiconductor, leading to electron emission over a vacuum gap. Theoretical analyses predict conversion efficiency that can match, or even exceed, the efficiency of traditional solar thermal and photovoltaic converters. Several materials have been examined as candidates for radiation absorbers and electron emitters, with no conclusion yet on the best set of materials to achieve high efficiency. Analyses have shown the complexity of the energy conversion and transport processes, and the significance of several loss mechanisms, requiring careful control of material properties and optimization of the device structure. Here we survey current research on PETE modeling, materials, and device configurations, outline the advances made, and stress the open issues and future research needed. Based on the substantial progress already made in this young topic, and the potential of high conversion efficiency based on theoretical performance limits, continued research in this direction is very promising and may yield a competitive technology for solar electricity generation.

Atomically dispersed metal sites in MOF-based materials for electrocatalytic and photocatalytic energy conversion.

PubMed

Liang, Zibin; Qu, Chong; Xia, Dingguo; Zou, Ruqiang; Xu, Qiang

2018-02-19

Metal sites play an essential role for both electrocatalytic and photocatalytic energy conversion applications. The highly ordered arrangements of the organic linkers and metal nodes and the well-defined pore structures of metal-organic frameworks (MOFs) make them ideal substrates to support atomically dispersed metal sites (ADMSs) located in their metal nodes, linkers, and pores. Besides, porous carbon materials doped with ADMSs can be derived from these ADMS-incorporated MOF precursors through controlled treatments. These ADMSs incorporated in pristine MOFs and MOF-derived carbon materials possess unique merits over the molecular or the bulk metal-based catalysts, bridging the gap between homogeneous and heterogeneous catalysts for energy conversion applications. In this review, recent progress and perspective of design and incorporation of ADMSs in pristine MOFs and MOF-derived materials for energy conversion applications are highlighted, which will hopefully promote further developments of advanced MOF-based catalysts in foreseeable future. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Research on Formation Mechanism of Dynamic Response and Residual Stress of Sheet Metal Induced by Laser Shock Wave

NASA Astrophysics Data System (ADS)

Feng, Aixin; Cao, Yupeng; Wang, Heng; Zhang, Zhengang

2018-01-01

In order to reveal the quantitative control of the residual stress on the surface of metal materials, the relevant theoretical and experimental studies were carried out to investigate the dynamic response of metal thin plates and the formation mechanism of residual stress induced by laser shock wave. In this paper, the latest research trends on the surface residual stress of laser shock processing technology were elaborated. The main progress of laser shock wave propagation mechanism and dynamic response, laser shock, and surface residual stress were discussed. It is pointed out that the multi-scale characterization of laser and material, surface residual stress and microstructure change is a new hotspot in laser shock strengthening technology.

Recent progress in research on tungsten materials for nuclear fusion applications in Europe

NASA Astrophysics Data System (ADS)

Rieth, M.; Dudarev, S. L.; Gonzalez de Vicente, S. M.; Aktaa, J.; Ahlgren, T.; Antusch, S.; Armstrong, D. E. J.; Balden, M.; Baluc, N.; Barthe, M.-F.; Basuki, W. W.; Battabyal, M.; Becquart, C. S.; Blagoeva, D.; Boldyryeva, H.; Brinkmann, J.; Celino, M.; Ciupinski, L.; Correia, J. B.; De Backer, A.; Domain, C.; Gaganidze, E.; García-Rosales, C.; Gibson, J.; Gilbert, M. R.; Giusepponi, S.; Gludovatz, B.; Greuner, H.; Heinola, K.; Höschen, T.; Hoffmann, A.; Holstein, N.; Koch, F.; Krauss, W.; Li, H.; Lindig, S.; Linke, J.; Linsmeier, Ch.; López-Ruiz, P.; Maier, H.; Matejicek, J.; Mishra, T. P.; Muhammed, M.; Muñoz, A.; Muzyk, M.; Nordlund, K.; Nguyen-Manh, D.; Opschoor, J.; Ordás, N.; Palacios, T.; Pintsuk, G.; Pippan, R.; Reiser, J.; Riesch, J.; Roberts, S. G.; Romaner, L.; Rosiński, M.; Sanchez, M.; Schulmeyer, W.; Traxler, H.; Ureña, A.; van der Laan, J. G.; Veleva, L.; Wahlberg, S.; Walter, M.; Weber, T.; Weitkamp, T.; Wurster, S.; Yar, M. A.; You, J. H.; Zivelonghi, A.

2013-01-01

The current magnetic confinement nuclear fusion power reactor concepts going beyond ITER are based on assumptions about the availability of materials with extreme mechanical, heat, and neutron load capacity. In Europe, the development of such structural and armour materials together with the necessary production, machining, and fabrication technologies is pursued within the EFDA long-term fusion materials programme. This paper reviews the progress of work within the programme in the area of tungsten and tungsten alloys. Results, conclusions, and future projections are summarized for each of the programme's main subtopics, which are: (1) fabrication, (2) structural W materials, (3) W armour materials, and (4) materials science and modelling. It gives a detailed overview of the latest results on materials research, fabrication processes, joining options, high heat flux testing, plasticity studies, modelling, and validation experiments.

Bioprinting and Biofabrication with Peptide and Protein Biomaterials.

PubMed

Boyd-Moss, Mitchell; Fox, Kate; Brandt, Milan; Nisbet, David; Williams, Richard

2017-01-01

The ability to fabricate artificial tissue constructs through the controlled organisation of cells, structures and signals within a biomimetic scaffold offers significant promise to the field of regenerative medicine, drug delivery and tissue engineering. Advances in additive manufacturing technologies have facilitated the printing of spatially defined cell-laden artificial tissue constructs capable of providing biomimetic spatiotemporal presentation of biological and physical cues to cells in a designed multicomponent structure. Despite significant progress in the field of bioprinting, a key challenge remains in developing and utilizing materials that can adequately recapitulate the complexities of the native extracellular matrix on a nanostructured, chemical level during the printing process. This gives rise to the need for suitable materials - particularly in establishing effective control over cell fate, tissue vascularization and innervation. Recently, significant interested has been invested into developing candidate materials using protein and peptide-derived biomaterials. The ability of these materials to form highly printable hydrogels which are reminiscent of the native ECM has seen significant use in a variety of regenative applications, including both organ bioprinting and non-organ bioprinting. Here, we discuss the emerging technologies for peptide-based bioprinting applications, highlighting bioink development and detailing bioprinter processors. Furthermore, this work presents application specific, peptide-based bioprinting approaches, and provides insight into current limitations and future perspectives of peptide-based bioprinting techniques.

Progress and Opportunities in Soft Photonics and Biologically Inspired Optics.

PubMed

Kolle, Mathias; Lee, Seungwoo

2018-01-01

Optical components made fully or partially from reconfigurable, stimuli-responsive, soft solids or fluids-collectively referred to as soft photonics-are poised to form the platform for tunable optical devices with unprecedented functionality and performance characteristics. Currently, however, soft solid and fluid material systems still represent an underutilized class of materials in the optical engineers' toolbox. This is in part due to challenges in fabrication, integration, and structural control on the nano- and microscale associated with the application of soft components in optics. These challenges might be addressed with the help of a resourceful ally: nature. Organisms from many different phyla have evolved an impressive arsenal of light manipulation strategies that rely on the ability to generate and dynamically reconfigure hierarchically structured, complex optical material designs, often involving soft or fluid components. A comprehensive understanding of design concepts, structure formation principles, material integration, and control mechanisms employed in biological photonic systems will allow this study to challenge current paradigms in optical technology. This review provides an overview of recent developments in the fields of soft photonics and biologically inspired optics, emphasizes the ties between the two fields, and outlines future opportunities that result from advancements in soft and bioinspired photonics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Micromechanics Based Failure Analysis of Heterogeneous Materials

NASA Astrophysics Data System (ADS)

Sertse, Hamsasew M.

In recent decades, heterogeneous materials are extensively used in various industries such as aerospace, defense, automotive and others due to their desirable specific properties and excellent capability of accumulating damage. Despite their wide use, there are numerous challenges associated with the application of these materials. One of the main challenges is lack of accurate tools to predict the initiation, progression and final failure of these materials under various thermomechanical loading conditions. Although failure is usually treated at the macro and meso-scale level, the initiation and growth of failure is a complex phenomena across multiple scales. The objective of this work is to enable the mechanics of structure genome (MSG) and its companion code SwiftComp to analyze the initial failure (also called static failure), progressive failure, and fatigue failure of heterogeneous materials using micromechanics approach. The initial failure is evaluated at each numerical integration point using pointwise and nonlocal approach for each constituent of the heterogeneous materials. The effects of imperfect interfaces among constituents of heterogeneous materials are also investigated using a linear traction-displacement model. Moreover, the progressive and fatigue damage analyses are conducted using continuum damage mechanics (CDM) approach. The various failure criteria are also applied at a material point to analyze progressive damage in each constituent. The constitutive equation of a damaged material is formulated based on a consistent irreversible thermodynamics approach. The overall tangent modulus of uncoupled elastoplastic damage for negligible back stress effect is derived. The initiation of plasticity and damage in each constituent is evaluated at each numerical integration point using a nonlocal approach. The accumulated plastic strain and anisotropic damage evolution variables are iteratively solved using an incremental algorithm. The damage analyses are performed for both brittle failure/high cycle fatigue (HCF) for negligible plastic strain and ductile failure/low cycle fatigue (LCF) for large plastic strain. The proposed approach is incorporated in SwiftComp and used to predict the initial failure envelope, stress-strain curve for various loading conditions, and fatigue life of heterogeneous materials. The combined effects of strain hardening and progressive fatigue damage on the effective properties of heterogeneous materials are also studied. The capability of the current approach is validated using several representative examples of heterogeneous materials including binary composites, continuous fiber-reinforced composites, particle-reinforced composites, discontinuous fiber-reinforced composites, and woven composites. The predictions of MSG are also compared with the predictions obtained using various micromechanics approaches such as Generalized Methods of Cells (GMC), Mori-Tanaka (MT), and Double Inclusions (DI) and Representative Volume Element (RVE) Analysis (called as 3-dimensional finite element analysis (3D FEA) in this document). This study demonstrates that a micromechanics based failure analysis has a great potential to rigorously and more accurately analyze initiation and progression of damage in heterogeneous materials. However, this approach requires material properties specific to damage analysis, which are needed to be independently calibrated for each constituent.

ECM-Based Materials in Cardiovascular Applications: Inherent Healing Potential and Augmentation of Native Regenerative Processes

PubMed Central

Piterina, Anna V.; Cloonan, Aidan J.; Meaney, Claire L.; Davis, Laura M.; Callanan, Anthony; Walsh, Michael T.; McGloughlin, Tim M.

2009-01-01

The in vivo healing process of vascular grafts involves the interaction of many contributing factors. The ability of vascular grafts to provide an environment which allows successful accomplishment of this process is extremely difficult. Poor endothelisation, inflammation, infection, occlusion, thrombosis, hyperplasia and pseudoaneurysms are common issues with synthetic grafts in vivo. Advanced materials composed of decellularised extracellular matrices (ECM) have been shown to promote the healing process via modulation of the host immune response, resistance to bacterial infections, allowing re-innervation and reestablishing homeostasis in the healing region. The physiological balance within the newly developed vascular tissue is maintained via the recreation of correct biorheology and mechanotransduction factors including host immune response, infection control, homing and the attraction of progenitor cells and infiltration by host tissue. Here, we review the progress in this tissue engineering approach, the enhancement potential of ECM materials and future prospects to reach the clinical environment. PMID:20057951

Observation of three-dimensional internal structure of steel materials by means of serial sectioning with ultrasonic elliptical vibration cutting.

PubMed

Fujisaki, K; Yokota, H; Nakatsuchi, H; Yamagata, Y; Nishikawa, T; Udagawa, T; Makinouchi, A

2010-01-01

A three-dimensional (3D) internal structure observation system based on serial sectioning was developed from an ultrasonic elliptical vibration cutting device and an optical microscope combined with a high-precision positioning device. For bearing steel samples, the cutting device created mirrored surfaces suitable for optical metallography, even for long-cutting distances during serial sectioning of these ferrous materials. Serial sectioning progressed automatically by means of numerical control. The system was used to observe inclusions in steel materials on a scale of several tens of micrometers. Three specimens containing inclusions were prepared from bearing steels. These inclusions could be detected as two-dimensional (2D) sectional images with resolution better than 1 mum. A three-dimensional (3D) model of each inclusion was reconstructed from the 2D serial images. The microscopic 3D models had sharp edges and complicated surfaces.

Issues Related to Obtaining Intelligence Quotient-Matched Controls in Autism Research

PubMed Central

Rao, Vanitha S.; Raman, Vijaya; Mysore, Ashok V.

2015-01-01

Background: Intelligence Quotient (IQ) is considered to be an index of global cognitive functioning and has traditionally been used as a fulcral measure in case-control studies in neuro-developmental disorders such as autism. Aim: The aim is to highlight the issues of “matching for IQ” with controls in autism research. Materials and Methods: Percentile scores on the Coloured Progressive Matrices of 20 children with autism in the age range of 5 to 12 years have been graphically compared with 21 age matched typically developing children. Results and Conclusions: The percentile scores of the so-called high functioning children with autism from special schools were well below that of typically developing children. There are many challenges when using IQ in case-control studies of autism. Alternative approaches need to be considered. PMID:25969598

Surface Modeling to Support Small-Body Spacecraft Exploration and Proximity Operations

NASA Technical Reports Server (NTRS)

Riedel, Joseph E.; Mastrodemos, Nickolaos; Gaskell, Robert W.

2011-01-01

In order to simulate physically plausible surfaces that represent geologically evolved surfaces, demonstrating demanding surface-relative guidance navigation and control (GN&C) actions, such surfaces must be made to mimic the geological processes themselves. A report describes how, using software and algorithms to model body surfaces as a series of digital terrain maps, a series of processes was put in place that evolve the surface from some assumed nominal starting condition. The physical processes modeled in this algorithmic technique include fractal regolith substrate texturing, fractally textured rocks (of empirically derived size and distribution power laws), cratering, and regolith migration under potential energy gradient. Starting with a global model that may be determined observationally or created ad hoc, the surface evolution is begun. First, material of some assumed strength is layered on the global model in a fractally random pattern. Then, rocks are distributed according to power laws measured on the Moon. Cratering then takes place in a temporal fashion, including modeling of ejecta blankets and taking into account the gravity of the object (which determines how much of the ejecta blanket falls back to the surface), and causing the observed phenomena of older craters being progressively buried by the ejecta of earlier impacts. Finally, regolith migration occurs which stratifies finer materials from coarser, as the fine material progressively migrates to regions of lower potential energy.

Core-melt source reduction system

DOEpatents

Forsberg, C.W.; Beahm, E.C.; Parker, G.W.

1995-04-25

A core-melt source reduction system for ending the progression of a molten core during a core-melt accident and resulting in a stable solid cool matrix. The system includes alternating layers of a core debris absorbing material and a barrier material. The core debris absorbing material serves to react with and absorb the molten core such that containment overpressurization and/or failure does not occur. The barrier material slows the progression of the molten core debris through the system such that the molten core has sufficient time to react with the core absorbing material. The system includes a provision for cooling the glass/molten core mass after the reaction such that a stable solid cool matrix results. 4 figs.

Core-melt source reduction system

DOEpatents

Forsberg, Charles W.; Beahm, Edward C.; Parker, George W.

1995-01-01

A core-melt source reduction system for ending the progression of a molten core during a core-melt accident and resulting in a stable solid cool matrix. The system includes alternating layers of a core debris absorbing material and a barrier material. The core debris absorbing material serves to react with and absorb the molten core such that containment overpressurization and/or failure does not occur. The barrier material slows the progression of the molten core debris through the system such that the molten core has sufficient time to react with the core absorbing material. The system includes a provision for cooling the glass/molten core mass after the reaction such that a stable solid cool matrix results.

Perovskite-Inspired Photovoltaic Materials: Toward Best Practices in Materials Characterization and Calculations

DOE PAGES

Hoye, Robert L. Z.; Schulz, Philip; Schelhas, Laura T.; ...

2017-02-28

Recently, there has been an explosive growth in research based on hybrid lead-halide perovskites for photovoltaics owing to rapid improvements in efficiency. The advent of these materials for solar applications has led to widespread interest in understanding the key enabling properties of these materials. This has resulted in renewed interest in related compounds and a search for materials that may replicate the defect-tolerant properties and long lifetimes of the hybrid lead-halide perovskites. Given the rapid pace of development of the field, the rises in efficiencies of these systems have outpaced the more basic understanding of these materials. Measuring or calculatingmore » the basic properties, such as crystal/electronic structure and composition, can be challenging because some of these materials have anisotropic structures, and/or are composed of both heavy metal cations and volatile, mobile, light elements. Some consequences are beam damage during characterization, composition change under vacuum, or compound effects, such as the alteration of the electronic structure through the influence of the substrate. These effects make it challenging to understand the basic properties integral to optoelectronic operation. Compounding these difficulties is the rapid pace with which the field progresses. This has created an ongoing need to continually evaluate best practices with respect to characterization and calculations, as well as to identify inconsistencies in reported values to determine if those inconsistencies are rooted in characterization methodology or materials synthesis. This article describes the difficulties in characterizing hybrid lead-halide perovskites and new materials and how these challenges may be overcome. The topic was discussed at a seminar at the 2015 Materials Research Society Fall Meeting & Exhibit. This article highlights the lessons learned from the seminar and the insights of some of the attendees, with reference to both recent literature and controlled experiments to illustrate the challenges discussed. The focus in this article is on crystallography, composition measurements, photoemission spectroscopy, and calculations on perovskites and new, related absorbers. We suggest how the reporting of the important artifacts could be streamlined between groups to ensure reproducibility as the field progresses.« less

Perovskite-Inspired Photovoltaic Materials: Toward Best Practices in Materials Characterization and Calculations

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

Hoye, Robert L. Z.; Schulz, Philip; Schelhas, Laura T.

Recently, there has been an explosive growth in research based on hybrid lead-halide perovskites for photovoltaics owing to rapid improvements in efficiency. The advent of these materials for solar applications has led to widespread interest in understanding the key enabling properties of these materials. This has resulted in renewed interest in related compounds and a search for materials that may replicate the defect-tolerant properties and long lifetimes of the hybrid lead-halide perovskites. Given the rapid pace of development of the field, the rises in efficiencies of these systems have outpaced the more basic understanding of these materials. Measuring or calculatingmore » the basic properties, such as crystal/electronic structure and composition, can be challenging because some of these materials have anisotropic structures, and/or are composed of both heavy metal cations and volatile, mobile, light elements. Some consequences are beam damage during characterization, composition change under vacuum, or compound effects, such as the alteration of the electronic structure through the influence of the substrate. These effects make it challenging to understand the basic properties integral to optoelectronic operation. Compounding these difficulties is the rapid pace with which the field progresses. This has created an ongoing need to continually evaluate best practices with respect to characterization and calculations, as well as to identify inconsistencies in reported values to determine if those inconsistencies are rooted in characterization methodology or materials synthesis. This article describes the difficulties in characterizing hybrid lead-halide perovskites and new materials and how these challenges may be overcome. The topic was discussed at a seminar at the 2015 Materials Research Society Fall Meeting & Exhibit. This article highlights the lessons learned from the seminar and the insights of some of the attendees, with reference to both recent literature and controlled experiments to illustrate the challenges discussed. The focus in this article is on crystallography, composition measurements, photoemission spectroscopy, and calculations on perovskites and new, related absorbers. We suggest how the reporting of the important artifacts could be streamlined between groups to ensure reproducibility as the field progresses.« less

Transition metal dichalcogenides and beyond: synthesis, properties, and applications of single- and few-layer nanosheets.

PubMed

Lv, Ruitao; Robinson, Joshua A; Schaak, Raymond E; Sun, Du; Sun, Yifan; Mallouk, Thomas E; Terrones, Mauricio

2015-01-20

CONSPECTUS: In the wake of the discovery of the remarkable electronic and physical properties of graphene, a vibrant research area on two-dimensional (2D) layered materials has emerged during the past decade. Transition metal dichalcogenides (TMDs) represent an alternative group of 2D layered materials that differ from the semimetallic character of graphene. They exhibit diverse properties that depend on their composition and can be semiconductors (e.g., MoS2, WS2), semimetals (e.g., WTe2, TiSe2), true metals (e.g., NbS2, VSe2), and superconductors (e.g., NbSe2, TaS2). The properties of TMDs can also be tailored according to the crystalline structure and the number and stacking sequence of layers in their crystals and thin films. For example, 2H-MoS2 is semiconducting, whereas 1T-MoS2 is metallic. Bulk 2H-MoS2 possesses an indirect band gap, but when 2H-MoS2 is exfoliated into monolayers, it exhibits direct electronic and optical band gaps, which leads to enhanced photoluminescence. Therefore, it is important to learn to control the growth of 2D TMD structures in order to exploit their properties in energy conversion and storage, catalysis, sensing, memory devices, and other applications. In this Account, we first introduce the history and structural basics of TMDs. We then briefly introduce the Raman fingerprints of TMDs of different layer numbers. Then, we summarize our progress on the controlled synthesis of 2D layered materials using wet chemical approaches, chemical exfoliation, and chemical vapor deposition (CVD). It is now possible to control the number of layers when synthesizing these materials, and novel van der Waals heterostructures (e.g., MoS2/graphene, WSe2/graphene, hBN/graphene) have recently been successfully assembled. Finally, the unique optical, electrical, photovoltaic, and catalytic properties of few-layered TMDs are summarized and discussed. In particular, their enhanced photoluminescence (PL), photosensing, photovoltaic conversion, and hydrogen evolution reaction (HER) catalysis are discussed in detail. Finally, challenges along each direction are described. For instance, how to grow perfect single crystalline monolayer TMDs without the presence of grain boundaries and dislocations is still an open question. Moreover, the morphology and crystal structure control of few-layered TMDs still requires further research. For wet chemical approaches and chemical exfoliation methods, it is still a significant challenge to control the lateral growth of TMDs without expansion in the c-axis direction. In fact, there is plenty of room in the 2D world beyond graphene. We envisage that with increasing progress in the controlled synthesis of these systems the unusual properties of mono- and few-layered TMDs and TMD heterostructures will be unveiled.

Continuing progress toward controlled intracellular delivery of semiconductor quantum dots

PubMed Central

Breger, Joyce; Delehanty, James B; Medintz, Igor L

2015-01-01

The biological applications of luminescent semiconductor quantum dots (QDs) continue to grow at a nearly unabated pace. This growth is driven, in part, by their unique photophysical and physicochemical properties which have allowed them to be used in many different roles in cellular biology including: as superior fluorophores for a wide variety of cellular labeling applications; as active platforms for assembly of nanoscale sensors; and, more recently, as a powerful tool to understand the mechanisms of nanoparticle mediated drug delivery. Given that controlled cellular delivery is at the intersection of all these applications, the latest progress in delivering QDs to cells is examined here. A brief discussion of relevant considerations including the importance of materials preparation and bioconjugation along with the continuing issue of endosomal sequestration is initially provided for context. Methods for the cellular delivery of QDs are then highlighted including those based on passive exposure, facilitated strategies that utilize peptides or polymers and fully active modalities such as electroporation and other mechanically based methods. Following on this, the exciting advent of QD cellular delivery using multiple or combined mechanisms is then previewed. Several recent methods reporting endosomal escape of QD materials in cells are also examined in detail with a focus on the mechanisms by which access to the cytosol is achieved. The ongoing debate over QD cytotoxicity is also discussed along with a perspective on how this field will continue to evolve in the future. PMID:25154379

Interactive modeling-synthesis-characterization approach towards controllable in situ self-assembly of artificial pinning centers in RE-123 films

NASA Astrophysics Data System (ADS)

Wu, Judy; Shi, Jack

2017-10-01

Raising critical current density J c in high temperature superconductors (HTSs) is an important strategy towards performance-cost balanced HTS technology for commercialization. The development of strong nanoscale artificial pinning centers (APCs) in HTS, such as YBa2Cu3O7 or RE-123 in general, represents one of the most exciting progressions in HTS material research in the last decade. Significantly raised J c has been demonstrated in APC/RE-123 nanocomposites by enhanced pinning on magnetic vortices in magnetic fields towards that demanded in practical applications. Among other processes, strain-mediated self-organization has been explored extensively for in situ formation of the APCs based on fundamental physics design rules. The desire in controlling the morphology, dimension, orientation, and concentration of APCs has led to a fundamental question on how strains interact in determining APCs at a macroscopic scale. Answering this question demands an interactive modeling-synthesis-characterization approach towards a thorough understanding of fundamental physics governing the strain-mediated self-organization of the APCs in the APC/RE-123 nanocomposites. Such an understanding is the key for a leap forward from the traditionally empirical method to materials-by-design to enable an optimal APC landscape to be achieved in epitaxial films of APC/YBCO nanocomposites under a precise guidance of fundamental physics. The paper intends to provide a review of recent progress made in the controllable generation of APCs using the interactive modeling-synthesis-characterization approach. The emphasis will be given to the understanding so far achieved using such an approach on the collective effect of the strain field on the morphology, dimension, and orientation of APCs in epitaxial APC/RE-123 nanocomposite films.

Combined spectrophotometry and tensile measurements of human connective tissues: potentials and limitations.

PubMed

Ernstberger, Markus; Sichting, Freddy; Baselt, Tobias; Hartmann, Peter; Aust, Gabriela; Hammer, Niels

2013-06-01

Strain-dependent transmission data of nine iliotibial tract specimens are determined using a custom-built optical setup with a halogen light source and an industrial norm material testing machine. Polarized light microscopy and hematoxylin-eosin staining indicated that lateral contraction of collagen structures is responsible for total intensity variations during a 20-cycle preconditioning and a 5-cycle tensile test. Tensile force progress is opposite to total transmission progress. Due to dehydration, wavelength-specific radiation intensity shifting is determined during the test, primarily noticeable in a water absorption band between 1400 and 1500 nm. The results show the capability of integrating spectrophotometry technology into biomechanics for determining structural alterations of human collagen due to applied strain. Being more sensitive to drying, spectrophotometry may likely serve as a quality control in stress-strain testing of biological structures.

Analyzing Students' Learning Progressions throughout a Teaching Sequence on Acoustic Properties of Materials with a Model-Based Inquiry Approach

ERIC Educational Resources Information Center

Hernández, María Isabel; Couso, Digna; Pintó, Roser

2015-01-01

The study we have carried out aims to characterize 15-to 16-year-old students' learning progressions throughout the implementation of a teaching-learning sequence on the acoustic properties of materials. Our purpose is to better understand students' modeling processes about this topic and to identify how the instructional design and actual…

AR and TD Fossil Energy Materials Program. Quarterly progress report for the period ending December 31, 1981

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

Not Available

1982-04-01

The ORNL Fossil Energy Materials Program Office compiles and issues this combined quarterly progress report from camera-ready copies submitted by each of the participating subcontractor organizations. This report of activities on the program is organized in accordance with a work breakdown structure defined in the AR and TD Fossil Energy Materials Program Plan for FY 1982-1986 in which projects are organized according to fossil energy technologies. This report is divided into parts and chapters with each part describing projects related to a particular fossil energy technology. Chapters within a part provide details of the various projects associated with that technology.more » We hope this series of AR and TD Fossil Energy Materials Program quarterly progress reports will aid in the dissemination of information developed on the program. Plans for the program will be issued annually. A draft of the program plan for FY 1982 to 1986 has been prepared and is in the review process. The implementation of these plans will be reflected by these quarterly progress reports, and this dissemination of information will bw augmented by topical or final reports as appropriate.« less

Supramolecular Approaches to Nanoscale Morphological Control in Organic Solar Cells

PubMed Central

Haruk, Alexander M.; Mativetsky, Jeffrey M.

2015-01-01

Having recently surpassed 10% efficiency, solar cells based on organic molecules are poised to become a viable low-cost clean energy source with the added advantages of mechanical flexibility and light weight. The best-performing organic solar cells rely on a nanostructured active layer morphology consisting of a complex organization of electron donating and electron accepting molecules. Although much progress has been made in designing new donor and acceptor molecules, rational control over active layer morphology remains a central challenge. Long-term device stability is another important consideration that needs to be addressed. This review highlights supramolecular strategies for generating highly stable nanostructured organic photovoltaic active materials by design. PMID:26110382

Charge-reversal nanoparticles: novel targeted drug delivery carriers.

PubMed

Chen, Xinli; Liu, Lisha; Jiang, Chen

2016-07-01

Spurred by significant progress in materials chemistry and drug delivery, charge-reversal nanocarriers are being developed to deliver anticancer formulations in spatial-, temporal- and dosage-controlled approaches. Charge-reversal nanoparticles can release their drug payload in response to specific stimuli that alter the charge on their surface. They can elude clearance from the circulation and be activated by protonation, enzymatic cleavage, or a molecular conformational change. In this review, we discuss the physiological basis for, and recent advances in the design of charge-reversal nanoparticles that are able to control drug biodistribution in response to specific stimuli, endogenous factors (changes in pH, redox gradients, or enzyme concentration) or exogenous factors (light or thermos-stimulation).

Microbiological surveillance and state of the art technological strategies for the prevention of dialysis water pollution.

PubMed

Bolasco, Piergiorgio; Contu, Antonio; Meloni, Patrizia; Vacca, Dorio; Galfrè, Andrea

2012-08-01

The present report attempts to illustrate the positive impact on the microbiological quality of dialysis patients over a 15-year period through the progressive implementation of state-of-the-art technological strategies and the optimization of microbiological surveillance procedures in five dialysis units in Sardinia. Following on better microbiological, quality controls of dialysis water and improvement of procedures and equipment, a drastic improvement of microbiological water quality was observed in a total of 945 samples. The main aim was to introduce the use of microbiological culture methods as recommended by the most important guidelines. The microbiological results obtained have led to a progressive refining of controls and introduction of new materials and equipment, including two-stage osmosis and piping distribution rings featuring a greater capacity to prevent biofilm adhesion. The actions undertaken have resulted in unexpected quality improvements. Dialysis water should be viewed by the nephrologist as a medicinal product exerting a demonstrable positive impact on microinflammation in dialysis patients. A synergic effort between nephrologists and microbiologists undoubtedly constitutes the most effective means of preventing dialysis infections.

The design and progress of a multidomain lifestyle intervention to improve brain health in middle-aged persons to reduce later Alzheimer's disease risk: The Gray Matters randomized trial.

PubMed

Norton, Maria C; Clark, Christine J; Tschanz, JoAnn T; Hartin, Phillip; Fauth, Elizabeth B; Gast, Julie A; Dorsch, Travis E; Wengreen, Heidi; Nugent, Chris; Robinson, W David; Lefevre, Michael; McClean, Sally; Cleland, Ian; Schaefer, Sydney Y; Aguilar, Sheryl

2015-06-01

Most Alzheimer's disease (AD) prevention studies focus on older adults or persons with existing cognitive impairment. This study describes the design and progress of a novel pilot intervention, the Gray Matters study. This proof-of-concept randomized controlled trial tests an evidence-based multidomain lifestyle intervention in 146 persons aged 40 to 64 years, in northern Utah. Data collectors were blinded to participants' randomization to treatment (n = 104) or control (n = 42). Intervention targeted physical activity, food choices, social engagement, cognitive simulation, sleep quality, and stress management, and uses a custom smartphone application, activity monitor, and educational materials. Secondary outcomes include biomarkers, body mass index, cognitive testing, and psychological surveys. Midway through the study, achievements include a 98.7% retention rate, a 96% rate of compliance with app data entry, and positive trends in behavioral change. Participants were empowered, learning that lifestyle might impact AD risk, exhibiting positive behavioral changes thus far.

Study on the new technology of removing gangue and retaining roadway in complicated roof condition

NASA Astrophysics Data System (ADS)

Chen, Yanhao; Jiang, Cong

2018-04-01

This article in view of the complex roof conditions was carried on study about the new technology of removing gangue and retaining roadway, and tells a method of progressive reinforced concrete wall segment with gangue to keep the roadway, the roadway beside the support system is mainly composed of the lining, waste rock wall and the outer wall, the wall and the outer wall of concrete material width to build the strength of the progressive type filling body, waste rock wall with woven bag with waste rock assembled, paragraphs geological survey on the actual distance should be based on working face. This method relies on the interior of the gangue wall to make the pressure control and allow the roof to sink. In this paper, the finite deformation control of the roof is realized by the gangue wall and the high strength filling body. This method has the characteristics of low entry cost, good forming of roadway, high security and good stability, and can be applied to complex geological conditions such as hard roof.

Microbiological Surveillance and State of the Art Technological Strategies for the Prevention of Dialysis Water Pollution

PubMed Central

Bolasco, Piergiorgio; Contu, Antonio; Meloni, Patrizia; Vacca, Dorio; Galfrè, Andrea

2012-01-01

Methods: The present report attempts to illustrate the positive impact on the microbiological quality of dialysis patients over a 15-year period through the progressive implementation of state-of-the-art technological strategies and the optimization of microbiological surveillance procedures in five dialysis units in Sardinia. Results: Following on better microbiological, quality controls of dialysis water and improvement of procedures and equipment, a drastic improvement of microbiological water quality was observed in a total of 945 samples. The main aim was to introduce the use of microbiological culture methods as recommended by the most important guidelines. The microbiological results obtained have led to a progressive refining of controls and introduction of new materials and equipment, including two-stage osmosis and piping distribution rings featuring a greater capacity to prevent biofilm adhesion. The actions undertaken have resulted in unexpected quality improvements. Conclusions: Dialysis water should be viewed by the nephrologist as a medicinal product exerting a demonstrable positive impact on microinflammation in dialysis patients. A synergic effort between nephrologists and microbiologists undoubtedly constitutes the most effective means of preventing dialysis infections. PMID:23066395

Characterizing automotive fuel cell materials by soft x-ray scanning transmission x-ray microscopy

NASA Astrophysics Data System (ADS)

Hitchcock, A. P.; Lee, V.; Wu, J.; West, M. M.; Cooper, G.; Berejnov, V.; Soboleva, T.; Susac, D.; Stumper, J.

2016-01-01

Proton-Exchange Membrane Fuel Cell (PEM-FC) based engines are being developed rapidly for near-term implementation in hydrogen fueled, mass production, personal automobiles. Research is focused on understanding and controlling various degradation processes (carbon corrosion, Pt migration, cold start), and reducing cost by reducing or eliminating Pt catalyst. We are using soft X-ray scanning transmission X-ray microscopy (STXM) at the S 2p, C 1s, O 1s and F 1s edges to study a variety of issues related to optimization of PEM-FC materials for automotive applications. A method to efficiently and accurately measure perfluorosulfonic acid distributions was developed and is being used to better understand how different loadings and preparation methods affect the ionomer distribution in the cathode. Progress towards an environmental cell capable of controlling the temperature and humidity of a PEM-FC sample in the STXM is described. Methods for studying the 3D chemical structure of PEM-FC are outlined.

Methods of measurement for semiconductor materials, process control, and devices

NASA Technical Reports Server (NTRS)

Bullis, W. M. (Editor)

1973-01-01

This progress report describes NBS activities directed toward the development of methods of measurement for semiconductor materials, process control, and devices. Significant accomplishments during this reporting period include design of a plan to provide standard silicon wafers for four-probe resistivity measurements for the industry, publication of a summary report on the photoconductive decay method for measuring carrier lifetime, publication of a comprehensive review of the field of wire bond fabrication and testing, and successful completion of organizational activity leading to the establishment of a new group on quality and hardness assurance in ASTM Committee F-1 on Electronics. Work is continuing on measurement of resistivity of semiconductor crystals; characterization of generation-recombination-trapping centers in silicon; study of gold-doped silicon; development of the infrared response technique; evaluation of wire bonds and die attachment; and measurement of thermal properties of semiconductor devices, delay time and related carrier transport properties in junction devices, and noise properties of microwave diodes.

Charge transport in organic semiconductors.

PubMed

Bässler, Heinz; Köhler, Anna

2012-01-01

Modern optoelectronic devices, such as light-emitting diodes, field-effect transistors and organic solar cells require well controlled motion of charges for their efficient operation. The understanding of the processes that determine charge transport is therefore of paramount importance for designing materials with improved structure-property relationships. Before discussing different regimes of charge transport in organic semiconductors, we present a brief introduction into the conceptual framework in which we interpret the relevant photophysical processes. That is, we compare a molecular picture of electronic excitations against the Su-Schrieffer-Heeger semiconductor band model. After a brief description of experimental techniques needed to measure charge mobilities, we then elaborate on the parameters controlling charge transport in technologically relevant materials. Thus, we consider the influences of electronic coupling between molecular units, disorder, polaronic effects and space charge. A particular focus is given to the recent progress made in understanding charge transport on short time scales and short length scales. The mechanism for charge injection is briefly addressed towards the end of this chapter.

Plasma-assisted interface engineering of boron nitride nanostructure films.

PubMed

Pakdel, Amir; Bando, Yoshio; Golberg, Dmitri

2014-10-28

Today many aspects of science and technology are progressing into the nanoscale realm where surfaces and interfaces are intrinsically important in determining properties and performances of materials and devices. One familiar phenomenon in which interfacial interactions play a major role is the wetting of solids. In this work we use a facile one-step plasma method to control the wettability of boron nitride (BN) nanostructure films via covalent chemical functionalization, while their surface morphology remains intact. By tailoring the concentration of grafted hydroxyl groups, superhydrophilic, hydrophilic, and hydrophobic patterns are created on the initially superhydrophobic BN nanosheet and nanotube films. Moreover, by introducing a gradient of the functional groups, directional liquid spreading toward increasing [OH] content is achieved on the films. The resulting insights are meant to illustrate great potentials of this method to tailor wettability of ceramic films, control liquid flow patterns for engineering applications such as microfluidics and biosensing, and improve the interfacial contact and adhesion in nanocomposite materials.

Characterizing automotive fuel cell materials by soft x-ray scanning transmission x-ray microscopy

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

Hitchcock, A. P., E-mail: aph@mcmaster.ca; Lee, V.; Wu, J.

Proton-Exchange Membrane Fuel Cell (PEM-FC) based engines are being developed rapidly for near-term implementation in hydrogen fueled, mass production, personal automobiles. Research is focused on understanding and controlling various degradation processes (carbon corrosion, Pt migration, cold start), and reducing cost by reducing or eliminating Pt catalyst. We are using soft X-ray scanning transmission X-ray microscopy (STXM) at the S 2p, C 1s, O 1s and F 1s edges to study a variety of issues related to optimization of PEM-FC materials for automotive applications. A method to efficiently and accurately measure perfluorosulfonic acid distributions was developed and is being used tomore » better understand how different loadings and preparation methods affect the ionomer distribution in the cathode. Progress towards an environmental cell capable of controlling the temperature and humidity of a PEM-FC sample in the STXM is described. Methods for studying the 3D chemical structure of PEM-FC are outlined.« less

Aggregation and morphology control enables multiple cases of high-efficiency polymer solar cells

PubMed Central

Liu, Yuhang; Zhao, Jingbo; Li, Zhengke; Mu, Cheng; Hu, Huawei; Jiang, Kui; Lin, Haoran; Ade, Harald; Yan, He

2014-01-01

Although the field of polymer solar cell has seen much progress in device performance in the past few years, several limitations are holding back its further development. For instance, current high-efficiency (>9.0%) cells are restricted to material combinations that are based on limited donor polymers and only one specific fullerene acceptor. Here we report the achievement of high-performance (efficiencies up to 10.8%, fill factors up to 77%) thick-film polymer solar cells for multiple polymer:fullerene combinations via the formation of a near-ideal polymer:fullerene morphology that contains highly crystalline yet reasonably small polymer domains. This morphology is controlled by the temperature-dependent aggregation behaviour of the donor polymers and is insensitive to the choice of fullerenes. The uncovered aggregation and design rules yield three high-efficiency (>10%) donor polymers and will allow further synthetic advances and matching of both the polymer and fullerene materials, potentially leading to significantly improved performance and increased design flexibility. PMID:25382026

Fusion materials semiannual progress report for the period ending December 31, 1996

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

NONE

1997-04-01

This is the twenty-first in a series of semiannual technical progress reports on fusion materials. This report combines the full spectrum of research and development activities on both metallic and non-metallic materials with primary emphasis on the effects of the neutronic and chemical environment on the properties and performance of materials for in-vessel components. This effort forms one element of the materials program being conducted in support of the Fusion Energy Sciences Program of the US Department of Energy. The other major element of the program is concerned with the interactions between reactor materials and the plasma and is reportedmore » separately. The report covers the following topics: vanadium alloys; silicon carbide composite materials; ferritic/martensitic steels; copper alloys and high heat flux materials; austenitic stainless steels; insulating ceramics and optical materials; solid breeding materials; radiation effects, mechanistic studies and experimental methods; dosimetry, damage parameters, and activation calculations; materials engineering and design requirements; and irradiation facilities, test matrices, and experimental methods.« less

Monitoring the Durability Performance of Concrete in Nuclear Waste Containment. Technical Progress Report No. 4

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

Ulm, Franz-Josef

2000-06-30

OAK-B135 Monitoring the Durability Performance of Concrete in Nuclear Waste Containment. Technical Progress Report No. 4. The analysis of the effect of cracks on the acceleration of the calcium leaching process of cement-based materials has been pursued. During the last period (Technical Progress Report No 3), we have introduced a modeling accounting for the high diffusivity of fractures in comparison with the weak solid material diffusivity. It has been shown through dimensional and asymptotic analysis that small fractures do not significantly accelerate the material aging process. This important result for the overall structural aging kinetics of containment structure has beenmore » developed in a paper submitted to the international journal ''Transport in Porous Media''.« less

Fulfilling the promise of the materials genome initiative with high-throughput experimental methodologies

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

Green, Martin L.; Choi, C. L.; Hattrick-Simpers, J. R.

The Materials Genome Initiative, a national effort to introduce new materials into the market faster and at lower cost, has made significant progress in computational simulation and modeling of materials. To build on this progress, a large amount of experimental data for validating these models, and informing more sophisticated ones, will be required. High-throughput experimentation generates large volumes of experimental data using combinatorial materials synthesis and rapid measurement techniques, making it an ideal experimental complement to bring the Materials Genome Initiative vision to fruition. This paper reviews the state-of-the-art results, opportunities, and challenges in high-throughput experimentation for materials design. Asmore » a result, a major conclusion is that an effort to deploy a federated network of high-throughput experimental (synthesis and characterization) tools, which are integrated with a modern materials data infrastructure, is needed.« less

Fulfilling the promise of the materials genome initiative with high-throughput experimental methodologies

DOE PAGES

Green, Martin L.; Choi, C. L.; Hattrick-Simpers, J. R.; ...

2017-03-28

The Materials Genome Initiative, a national effort to introduce new materials into the market faster and at lower cost, has made significant progress in computational simulation and modeling of materials. To build on this progress, a large amount of experimental data for validating these models, and informing more sophisticated ones, will be required. High-throughput experimentation generates large volumes of experimental data using combinatorial materials synthesis and rapid measurement techniques, making it an ideal experimental complement to bring the Materials Genome Initiative vision to fruition. This paper reviews the state-of-the-art results, opportunities, and challenges in high-throughput experimentation for materials design. Asmore » a result, a major conclusion is that an effort to deploy a federated network of high-throughput experimental (synthesis and characterization) tools, which are integrated with a modern materials data infrastructure, is needed.« less

Change in Periodontitis during Pregnancy and Risk of Preterm Birth and Low Birthweight

PubMed Central

Michalowicz, Bryan S.; Hodges, James S.; Novak, M. John; Buchanan, William; DiAngelis, Anthony J.; Papapanou, Panos N.; Mitchell, Dennis A.; Ferguson, James E.; Lupo, Virginia R.; Bofill, James; Matseoane, Stephen

2009-01-01

Aim Determine if periodontitis progression during pregnancy is associated with adverse birth outcomes. Materials and Methods We used clinical data and birth outcomes from the OPT Study, which randomized women to receive periodontal treatment before 21 weeks gestation (N=413) or after delivery (410). Birth outcomes were available for 812 women and follow-up periodontal data for 722, including 75 whose pregnancies ended <37 weeks. Periodontitis progression was defined as ≥ 3mm loss of clinical attachment. Birth outcomes were compared between non-progressing and progressing groups using the log rank and t tests, separately in all women and in untreated controls. Results The distribution of gestational age at the end of pregnancy (P > 0.1) and mean birthweight (3295 versus 3184 grams, P = 0.11) did not differ significantly between women with and without disease progression. Gestational age and birthweight were not associated with change from baseline in percent of tooth sites with bleeding on probing or between those who did versus did not progress according to a published definition of disease progression (P > 0.05). Conclusions In these women with periodontitis and within this study’s limitations, disease progression was not associated with increased risk for delivering a preterm or low birthweight infant. Clinical Relevance Scientific Rationale Maternal periodontitis and disease progression during pregnancy have been associated with elevated risk for preterm birth. We used data from a recent clinical trial to explore possible associations between progressive periodontitis and birth outcomes. Principal Findings The distribution of gestational age at delivery and mean birthweights did not differ significantly between women who experienced progressive periodontitis and those who did not. Clinical Implication While it is important to treat dental diseases, including periodontitis, during pregnancy, women whose periodontal condition worsens during pregnancy are not at elevated risk for adverse pregnancy outcomes. PMID:19426177

Damage progression in Composite Structures

NASA Technical Reports Server (NTRS)

Minnetyan, Levon

1996-01-01

A computational simulation tool is used to evaluate the various stages of damage progression in composite materials during Iosipescu sheat testing. Unidirectional composite specimens with either the major or minor material axis in the load direction are considered. Damage progression characteristics are described for each specimen using two types of boundary conditions. A procedure is outlined regarding the use of computational simulation in composites testing. Iosipescu shear testing using the V-notched beam specimen is a convenient method to measure both shear strength and shear stiffness simultaneously. The evaluation of composite test response can be made more productive and informative via computational simulation of progressive damage and fracture. Computational simulation performs a complete evaluation of laminated composite fracture via assessment of ply and subply level damage/fracture processes.

Recent progress in half-Heusler thermoelectric materials

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

Huang, Lihong; Zhang, Qinyong; Yuan, Bo

2016-04-15

Highlights: • Summarize the recent progress and advances in HH thermoelectric materials. • Preparing nanocomposites could reduce thermal conductivity. • Introducing enhance phonon scattering could further reduce the thermal conductivity. • Forming ternary systems to reducing the cost effectively. • The new class of HHs presents another opportunity to further optimize the HH system. - Abstract: Half-Heusler (HH) thermoelectric (TE) materials have been attracting extensive research interest over the last two decades, owing to their thermal stability, mechanical strength, and moderate ZT. This material system are potential candidates for medium to high temperature applications, which is close to the temperaturemore » range of most industrial waste heat sources. In this mini-review article, we briefly summarize the recent progress and advances in HH thermoelectric materials. Some effectively available approaches, such as HH nanocomposites to reduce thermal conductivity, using larger atomic mass and size differences to enhance phonon scattering to further reduce the thermal conductivity, forming ternary systems following the cost effective approach. In addition, new thermoelectric HH members are also discussed in this article, which points out that many new HH compounds may be possible for TE applications.« less

40 CFR 35.938-6 - Progress payments to contractors.

Code of Federal Regulations, 2014 CFR

2014-07-01

... FEDERAL ASSISTANCE STATE AND LOCAL ASSISTANCE Grants for Construction of Treatment Works-Clean Water Act... should make prompt progress payment to subcontractors and suppliers for eligible construction, material... under a contract under an EPA construction grant. (b) Conditions of progress payments. For purposes of...

Fundamental and progress of Bi2Te3-based thermoelectric materials

NASA Astrophysics Data System (ADS)

Hong, Min; Chen, Zhi-Gang; Zou, Jin

2018-04-01

Thermoelectric materials, enabling the directing conversion between heat and electricity, are one of the promising candidates for overcoming environmental pollution and the upcoming energy shortage caused by the over-consumption of fossil fuels. Bi2Te3-based alloys are the classical thermoelectric materials working near room temperature. Due to the intensive theoretical investigations and experimental demonstrations, significant progress has been achieved to enhance the thermoelectric performance of Bi2Te3-based thermoelectric materials. In this review, we first explored the fundamentals of thermoelectric effect and derived the equations for thermoelectric properties. On this basis, we studied the effect of material parameters on thermoelectric properties. Then, we analyzed the features of Bi2Te3-based thermoelectric materials, including the lattice defects, anisotropic behavior and the strong bipolar conduction at relatively high temperature. Then we accordingly summarized the strategies for enhancing the thermoelectric performance, including point defect engineering, texture alignment, and band gap enlargement. Moreover, we highlighted the progress in decreasing thermal conductivity using nanostructures fabricated by solution grown method, ball milling, and melt spinning. Lastly, we employed modeling analysis to uncover the principles of anisotropy behavior and the achieved enhancement in Bi2Te3, which will enlighten the enhancement of thermoelectric performance in broader materials.

Application of Nanostructures in Electrochromic Materials and Devices: Recent Progress

PubMed Central

Wang, Jinmin; Sun, Xiao Wei; Jiao, Zhihui

2010-01-01

The recent progress in application of nanostructures in electrochromic materials and devices is reviewed. ZnO nanowire array modified by viologen and WO3, crystalline WO3 nanoparticles and nanorods, mesoporous WO3 and TiO2, poly(3,4-ethylenedioxythiophene) nanotubes, Prussian blue nanoinks and nanostructures in switchable mirrors are reviewed. The electrochromic properties were significantly enhanced by applying nanostructures, resulting in faster switching responses, higher stability and higher optical contrast. A perspective on the development trends in electrochromic materials and devices is also proposed. PMID:28883368

Progress of Application Researches of Porous Fiber Metals

PubMed Central

Xi, Zhengping; Zhu, Jilei; Tang, Huiping; Ao, Qingbo; Zhi, Hao; Wang, Jianyong; Li, Cheng

2011-01-01

Metal fiber porous materials with intrinsic properties of metal and functional properties of porous materials have received a great deal of attention in the fundamental research and industry applications. With developments of the preparation technologies and industrial requirements, porous fiber metals with excellent properties are developed and applied in many industry areas, e.g., sound absorption, heat transfer, energy absorption and lightweight structures. The applied research progress of the metal fiber porous materials in such application areas based on the recent work in our group was reviewed in this paper. PMID:28879952

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

Wang Hua; Department of Radiation Oncology, Cancer Hospital of Jiangxi Province, Jiangxi Province; Li Yexiong, E-mail: yexiong@yahoo.com

Purpose: The value of intensity-modulated radiotherapy (IMRT) for early-stage nasal NK/T-cell lymphoma has not been previously reported. The aim of the present study was to assess the dosimetric parameters, toxicity, and treatment outcomes of patients with nasal NK/T-cell lymphoma. Methods and Materials: Between 2003 and 2008, 42 patients with early-stage nasal NK/T-cell lymphoma underwent definitive high-dose and extended involved-field IMRT with or without combination chemotherapy. The median radiation dose to the primary tumor was 50 Gy. The dose-volume histograms of the target volume and critical normal structures were evaluated in all patients. The locoregional control, overall survival, and progression-free survivalmore » were calculated using the Kaplan-Meier method. Results: The average mean dose delivered to the planning target volume was 55.5 Gy. Only 1.3% and 2.5% of the planning target volume received <90% and 95% of the prescribed dose, respectively, indicating excellent planning target volume coverage. The mean dose and average dose to the parotid glands was 15 Gy and 14 Gy, respectively. With a median follow-up time of 27 months, the 2-year locoregional control, overall survival, and progression-free survivalrate was 93%, 78%, and 74%, respectively. No Grade 4 or 5 acute or late toxicity was reported. Conclusions: High-dose and extended involved-field IMRT for patients with early-stage nasal NK/T-cell lymphoma showed favorable locoregional control, overall survival, and progression-free survival, with mild toxicity. The dose constraints of IMRT for the parotid glands can be limited to <20 Gy in these patients.« less

Progressive Failure Analysis Methodology for Laminated Composite Structures

NASA Technical Reports Server (NTRS)

Sleight, David W.

1999-01-01

A progressive failure analysis method has been developed for predicting the failure of laminated composite structures under geometrically nonlinear deformations. The progressive failure analysis uses C(exp 1) shell elements based on classical lamination theory to calculate the in-plane stresses. Several failure criteria, including the maximum strain criterion, Hashin's criterion, and Christensen's criterion, are used to predict the failure mechanisms and several options are available to degrade the material properties after failures. The progressive failure analysis method is implemented in the COMET finite element analysis code and can predict the damage and response of laminated composite structures from initial loading to final failure. The different failure criteria and material degradation methods are compared and assessed by performing analyses of several laminated composite structures. Results from the progressive failure method indicate good correlation with the existing test data except in structural applications where interlaminar stresses are important which may cause failure mechanisms such as debonding or delaminations.

Emerging chitin and chitosan nanofibrous materials for biomedical applications

NASA Astrophysics Data System (ADS)

Ding, Fuyuan; Deng, Hongbing; Du, Yumin; Shi, Xiaowen; Wang, Qun

2014-07-01

Over the past several decades, we have witnessed significant progress in chitosan and chitin based nanostructured materials. The nanofibers from chitin and chitosan with appealing physical and biological features have attracted intense attention due to their excellent biological properties related to biodegradability, biocompatibility, antibacterial activity, low immunogenicity and wound healing capacity. Various methods, such as electrospinning, self-assembly, phase separation, mechanical treatment, printing, ultrasonication and chemical treatment were employed to prepare chitin and chitosan nanofibers. These nanofibrous materials have tremendous potential to be used as drug delivery systems, tissue engineering scaffolds, wound dressing materials, antimicrobial agents, and biosensors. This review article discusses the most recent progress in the preparation and application of chitin and chitosan based nanofibrous materials in biomedical fields.

Solid State Division progress report, September 30, 1981

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

Not Available

1982-04-01

Progress made during the 19 months from March 1, 1980, through September 30, 1981, is reported in the following areas: theoretical solid state physics (surfaces, electronic and magnetic properties, particle-solid interactions, and laser annealing); surface and near-surface properties of solids (plasma materials interactions, ion-solid interactions, pulsed laser annealing, and semiconductor physics and photovoltaic conversion); defects in solids (radiation effects, fracture, and defects and impurities in insulating crystals); transport properties of solids (fast-ion conductors, superconductivity, and physical properties of insulating materials); neutron scattering (small-angle scattering, lattice dynamics, and magnetic properties); crystal growth and characterization (nuclear waste forms, ferroelectric mateirals, high-temperature materials,more » and special materials); and isotope research materials. Publications and papers are listed. (WHK)« less

Looking into the Future: Toward Advanced 3D Biomaterials for Stem-Cell-Based Regenerative Medicine.

PubMed

Liu, Zhongmin; Tang, Mingliang; Zhao, Jinping; Chai, Renjie; Kang, Jiuhong

2018-04-01

Stem-cell-based therapies have the potential to provide novel solutions for the treatment of a variety of diseases, but the main obstacles to such therapies lie in the uncontrolled differentiation and functional engraftment of implanted tissues. The physicochemical microenvironment controls the self-renewal and differentiation of stem cells, and the key step in mimicking the stem cell microenvironment is to construct a more physiologically relevant 3D culture system. Material-based 3D assemblies of stem cells facilitate the cellular interactions that promote morphogenesis and tissue organization in a similar manner to that which occurs during embryogenesis. Both natural and artificial materials can be used to create 3D scaffolds, and synthetic organic and inorganic porous materials are the two main kinds of artificial materials. Nanotechnology provides new opportunities to design novel advanced materials with special physicochemical properties for 3D stem cell culture and transplantation. Herein, the advances and advantages of 3D scaffold materials, especially with respect to stem-cell-based therapies, are first outlined. Second, the stem cell biology in 3D scaffold materials is reviewed. Third, the progress and basic principles of developing 3D scaffold materials for clinical applications in tissue engineering and regenerative medicine are reviewed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Learning Progressions Provide Road Maps for the Development and Validity of Assessments and Curriculum Materials

ERIC Educational Resources Information Center

Krajcik, Joseph

2011-01-01

Paul Black, Mark Wilson, and Shih-Ying Yao in "Road Maps for Learning: A Guide to the Navigation of Learning Progressions" provide a number of important ideas to consider regarding the development of assessments and curriculum materials to support development of core ideas. One major idea that the author found most valuable is the focus on student…

A system identification approach for developing model predictive controllers of antibody quality attributes in cell culture processes.

PubMed

Downey, Brandon; Schmitt, John; Beller, Justin; Russell, Brian; Quach, Anthony; Hermann, Elizabeth; Lyon, David; Breit, Jeffrey

2017-11-01

As the biopharmaceutical industry evolves to include more diverse protein formats and processes, more robust control of Critical Quality Attributes (CQAs) is needed to maintain processing flexibility without compromising quality. Active control of CQAs has been demonstrated using model predictive control techniques, which allow development of processes which are robust against disturbances associated with raw material variability and other potentially flexible operating conditions. Wide adoption of model predictive control in biopharmaceutical cell culture processes has been hampered, however, in part due to the large amount of data and expertise required to make a predictive model of controlled CQAs, a requirement for model predictive control. Here we developed a highly automated, perfusion apparatus to systematically and efficiently generate predictive models using application of system identification approaches. We successfully created a predictive model of %galactosylation using data obtained by manipulating galactose concentration in the perfusion apparatus in serialized step change experiments. We then demonstrated the use of the model in a model predictive controller in a simulated control scenario to successfully achieve a %galactosylation set point in a simulated fed-batch culture. The automated model identification approach demonstrated here can potentially be generalized to many CQAs, and could be a more efficient, faster, and highly automated alternative to batch experiments for developing predictive models in cell culture processes, and allow the wider adoption of model predictive control in biopharmaceutical processes. © 2017 The Authors Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers Biotechnol. Prog., 33:1647-1661, 2017. © 2017 The Authors Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers.

The pumping lid: investigating multi-material 3D printing for equipment-free, programmable generation of positive and negative pressures for microfluidic applications.

PubMed

Begolo, Stefano; Zhukov, Dmitriy V; Selck, David A; Li, Liang; Ismagilov, Rustem F

2014-12-21

Equipment-free pumping is a challenging problem and an active area of research in microfluidics, with applications for both laboratory and limited-resource settings. This paper describes the pumping lid method, a strategy to achieve equipment-free pumping by controlled generation of pressure. Pressure was generated using portable, lightweight, and disposable parts that can be integrated with existing microfluidic devices to simplify workflow and eliminate the need for pumping equipment. The development of this method was enabled by multi-material 3D printing, which allows fast prototyping, including composite parts that combine materials with different mechanical properties (e.g. both rigid and elastic materials in the same part). The first type of pumping lid we describe was used to produce predictable positive or negative pressures via controlled compression or expansion of gases. A model was developed to describe the pressures and flow rates generated with this approach and it was validated experimentally. Pressures were pre-programmed by the geometry of the parts and could be tuned further even while the experiment was in progress. Using multiple lids or a composite lid with different inlets enabled several solutions to be pumped independently in a single device. The second type of pumping lid, which relied on vapor-liquid equilibrium to generate pressure, was designed, modeled, and experimentally characterized. The pumping lid method was validated by controlling flow in different types of microfluidic applications, including the production of droplets, control of laminar flow profiles, and loading of SlipChip devices. We believe that applying the pumping lid methodology to existing microfluidic devices will enhance their use as portable diagnostic tools in limited resource settings as well as accelerate adoption of microfluidics in laboratories.

Recent Advances in Nanobiotechnology and High-Throughput Molecular Techniques for Systems Biomedicine

PubMed Central

Kim, Eung-Sam; Ahn, Eun Hyun; Chung, Euiheon; Kim, Deok-Ho

2013-01-01

Nanotechnology-based tools are beginning to emerge as promising platforms for quantitative high-throughput analysis of live cells and tissues. Despite unprecedented progress made over the last decade, a challenge still lies in integrating emerging nanotechnology-based tools into macroscopic biomedical apparatuses for practical purposes in biomedical sciences. In this review, we discuss the recent advances and limitations in the analysis and control of mechanical, biochemical, fluidic, and optical interactions in the interface areas of nanotechnology-based materials and living cells in both in vitro and in vivo settings. PMID:24258011

A comparison of forming technologies for ceramic gas-turbine engine components

NASA Technical Reports Server (NTRS)

Hengst, R. R.; Heichel, D. N.; Holowczak, J. E.; Taglialavore, A. P.; Mcentire, B. J.

1990-01-01

For over ten years, injection molding and slip casting have been actively developed as forming techniques for ceramic gas turbine components. Co-development of these two processes has continued within the U.S. DOE-sponsored Advanced Turbine Technology Application Project (ATTAP). Progress within ATTAP with respect to these two techniques is summarized. A critique and comparison of the two processes are given. Critical aspects of both processes with respect to size, dimensional control, material properties, quality, cost, and potential for manufacturing scale-up are discussed.

Development and demonstration of manufacturing processes for fabricating graphite/Larc-160 polyimide structural elements, part 4, paragraph B

NASA Technical Reports Server (NTRS)

1981-01-01

Progress in the development of processes for production of Celion/LARC-160 graphite-polyimide materials, quality control, and the fabrication of Space Shuttle composite structure components is reported. Liquid chromatographic analyses of three repeatibility batches were performed and are compared to previous Hexcel standard production and to variables study LARC-160 intermediate resins. Development of processes for chopped fiber molding are described and flexural strength, elastic modulus, and other physical and mechanical properties of the molding are presented.

Active monitoring as cognitive control of grinders design

NASA Astrophysics Data System (ADS)

Flizikowski, Jozef B.; Mrozinski, Adam; Tomporowski, Andrzej

2017-03-01

A general monitoring methodology applicable to plastics recyclates grinding processes development for energy engineering, has been presented in this work. The method includes two beings: mathematical aiding an invention and working of a novelty. The common set is composed of characteristics, structure, relationships of knowledge about states and transformations, effectiveness and progress of the devices and machinery engineering, e.g. breaking up in the energy-materials recycling process. This innovations theory is identified by the valuation, estimation, testing and creative archiving the elaborated character and structure of the invention and grinders construction development.

Semiconductor technology program. Progress briefs

NASA Technical Reports Server (NTRS)

Bullis, W. M. (Editor)

1979-01-01

The current status of NBS work on measurement technology for semiconductor materials, process control, and devices is reported. Results of both in-house and contract research are covered. Highlighted activities include modeling of diffusion processes, analysis of model spreading resistance data, and studies of resonance ionization spectroscopy, resistivity-dopant density relationships in p-type silicon, deep level measurements, photoresist sensitometry, random fault measurements, power MOSFET thermal characteristics, power transistor switching characteristics, and gross leak testing. New and selected on-going projects are described. Compilations of recent publications and publications in press are included.

Electron tubes for industrial applications

NASA Astrophysics Data System (ADS)

Gellert, Bernd

1994-05-01

This report reviews research and development efforts within the last years for vacuum electron tubes, in particular power grid tubes for industrial applications. Physical and chemical effects are discussed that determine the performance of todays devices. Due to the progress made in the fundamental understanding of materials and newly developed processes the reliability and reproducibility of power grid tubes could be improved considerably. Modern computer controlled manufacturing methods ensure a high reproducibility of production and continuous quality certification according to ISO 9001 guarantees future high quality standards. Some typical applications of these tubes are given as an example.

Recent advances in nanobiotechnology and high-throughput molecular techniques for systems biomedicine.

PubMed

Kim, Eung-Sam; Ahn, Eun Hyun; Chung, Euiheon; Kim, Deok-Ho

2013-12-01

Nanotechnology-based tools are beginning to emerge as promising platforms for quantitative high-throughput analysis of live cells and tissues. Despite unprecedented progress made over the last decade, a challenge still lies in integrating emerging nanotechnology-based tools into macroscopic biomedical apparatuses for practical purposes in biomedical sciences. In this review, we discuss the recent advances and limitations in the analysis and control of mechanical, biochemical, fluidic, and optical interactions in the interface areas of nanotechnologybased materials and living cells in both in vitro and in vivo settings.

Chemistry and materials science progress report, FY 1994

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

NONE

1995-07-01

Research is reported in the areas of surface science, fundamentals of the physics and processing of metals, energetic materials, transactinide materials and properties and other indirectly related areas of weapons research.

Stereotactic Body Radiation Therapy for Oligometastatic Prostate Cancer

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

Muldermans, Jonathan L.; Romak, Lindsay B.; Kwon, Eugene D.

Purpose: To review outcomes of patients with oligometastatic prostate cancer (PCa) treated with stereotactic body radiation therapy (SBRT) and to identify variables associated with local failure. Methods and Materials: We retrospectively reviewed records of patients treated with SBRT for oligometastatic PCa. Metastasis control (ie, control of the treated lesion, MC), biochemical progression-free survival, distant progression-free survival, and overall survival were estimated with the Kaplan-Meier method. Results: Sixty-six men with 81 metastatic PCa lesions, 50 of which were castrate-resistant, were included in the analysis. Lesions were in bone (n=74), lymph nodes (n=6), or liver (n=1). Stereotactic body radiation therapy was deliveredmore » in 1 fraction to 71 lesions (88%), at a median dose of 16 Gy (range, 16-24 Gy). The remaining lesions received 30 Gy in 3 fractions (n=6) or 50 Gy in 5 fractions (n=4). Median follow-up was 16 months (range, 3-49 months). Estimated MC at 2 years was 82%. Biochemical progression-free survival, distant progression-free survival, and overall survival were 54%, 45%, and 83%, respectively. On multivariate analysis, only the dose of SBRT was significantly associated with MC; lesions treated with 16 Gy had 58% MC, and those treated with ≥18 Gy had 95% MC at 2 years (P≤.001). At 2 years, MC for lesions treated with 18 Gy (n=21) was 88%. No patient treated with ≥18 Gy in a single fraction or with any multifraction regimen had local failure. Six patients (9%) had grade 1 pain flare, and 2 (3%) had grade 2 pain flare. No grade 2 or greater late toxicities were reported. Conclusions: Stereotactic body radiation therapy for patients with oligometastatic prostate cancer provided optimal metastasis control and acceptable toxicity with doses ≥18 Gy. Biochemical progression-free survival was 54% at 16 months with the inclusion of SBRT in the treatment regimen. Stereotactic body radiation therapy should be considered in patients with castration-refractory, oligometastatic prostate cancer who have limited options for systemic therapy.« less

Recent progress in plasma-assisted synthesis and modification of 2D materials

NASA Astrophysics Data System (ADS)

Han, Zhao Jun; Murdock, Adrian T.; Seo, Dong Han; Bendavid, Avi

2018-07-01

Plasma represents an important technique for both the synthesis and modification of two-dimensional (2D) materials, owing to the unique plasma-material interactions which can enable effective energy transfer at the nanoscale. Non-equilibrium and non-thermal plasma techniques have been widely applied on various 2D materials, including graphene, silicene, germanene, phosphorene, hexagonal boron nitride (h-BN), and transition metal dichalcogenides such as MoS2 and WS2. Here, we review the recent progress in plasma-assisted synthesis and modification (e.g. functionalisation, doping and etching) of 2D materials and discuss the potential applications of this unique branch of 2D materials. Challenges and future research opportunities in the relevant research field are also discussed. The primary aim of this Review is to provide a better understanding of the plasma-assisted processes and to promote the utilization of 2D materials for advanced electronic, optoelectronic, sensing and energy storage applications.

[Progress in researches on pathogens, epidemiology and integrated control of diseases on Salvia miltiorrhiza in China].

PubMed

Wang, Tie-Lin; Guan, Wei; Sun, Kai; Wang, Sheng; Chi, Xiu-Lian; Guo, Lan-Ping

2018-06-01

Danshen (Salvia miltiorrhiza) is a perennial herbal plant as a bulk commodity of traditional Chinese medicinal material. With the growing market demand, the planting scale of Danshen has been fast enlarged. The occurance of diseases on Danshen has become as a major threaten of its production. Root diseases are most devastated on Danshen. Rootrot is the most important disease, and Fusarium wilt comes second. Leaf spot occurs most on aerial part of Danshen. In the Danshen industry, the chemical control is most commonly used, with biological agents as supplements. This review summarized the symptom, pathogen, epidemiology, and control method of 7 diseases on Danshen (rootrot, Fusarium wilt, southern blight, root knot nematode, leaf spot, leaf red and virus diseases), providing guidelines for disease diagnostics, pathogen isolation and identification, proper pesticide application and integrated control. Copyright© by the Chinese Pharmaceutical Association.

Laminar flow control, 1976 - 1982: A selected annotated bibliography

NASA Technical Reports Server (NTRS)

Tuttle, M. H.; Maddalon, D. V.

1982-01-01

Laminar Flow Control technology development has undergone tremendous progress in recent years as focused research efforts in materials, aerodynamics, systems, and structures have begun to pay off. A virtual explosion in the number of research papers published on this subject has occurred since interest was first stimulated by the 1976 introduction of NASA's Aircraft Energy Efficiency Laminar Flow Control Program. The purpose of this selected bibliography is to list available, unclassified laminar flow (both controlled and natural) research completed from about 1975 to mid 1982. Some earlier pertinent reports are included but listed separately in the Appendix. Reports listed herein emphasize aerodynamics and systems studies, but some structures work is also summarized. Aerodynamic work is mainly limited to the subsonic and transonic sped regimes. Because wind-tunnel flow qualities, such as free stream disturbance level, play such an important role in boundary-layer transition, much recent research has been done in this area and it is also included.

Recent developments of post-modification of biochar for electrochemical energy storage.

PubMed

Cheng, Bin-Hai; Zeng, Raymond J; Jiang, Hong

2017-12-01

Biochar is a common byproduct from thermochemical conversion of biomass to produce bioenergy. However, the biochar features, such as morphology, porosity and surface chemistry, cannot be well controlled in conventional conversion approaches, limiting the wide application of raw biochar. Aiming to meet the specific requirements, post-modification of raw biochar was frequently conducted to improve the quality. In this review, recent developments regarding post-modification methods of biochar are presented and discussed. Progresses on the applications of post modified biochar as electrode materials for supercapacitors are intensively summarized. This review aims to reveal the key factors that affecting the performance of biochar-based supercapacitors, and provide guidance for rationalizing the modification methods to expand the applications of biochar-based functional materials in supercapacitors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Relation between adolescent idiopathic scoliosis and morphologic somatotypes.

PubMed

LeBlanc, R; Labelle, H; Rivard, C H; Poitras, B

1997-11-01

A prospective and controlled comparative study. To verify the difference in morphologic appearance between a group of adolescents with progressive adolescent idiopathic scoliosis and a control group of normal adolescents. In a previous retrospective study, the possibility of a relation between progressive adolescent idiopathic scoliosis and specific morphotypes was demonstrated. Fifty-two adolescent girls with progressive adolescent idiopathic scoliosis were compared with an age-matched control group of 62 unaffected girls using a classification technique based on morphologic somatotypes. Morphotypes were evaluated with standardized pre-established criteria based on Sheldon's technique. Patients with progressive adolescent idiopathic scoliosis showed significantly less mesomorphism (mean value of 0.88 +/- 0.51) than control girls (mean value of 1.72 +/- 0.52). Adolescent girls with progressive adolescent idiopathic scoliosis have a morphologic somatotype that is different from the normal adolescent population. Subjects with progressive adolescent idiopathic scoliosis are significantly less mesomorphic than control girls. This observation may be of value as a predictive factor for early identification of subjects with adolescent idiopathic scoliosis at greater risk of progression.

U.S.-Russian cooperation in nuclear disarmament and nonproliferation

NASA Astrophysics Data System (ADS)

Podvig, Pavel

2010-02-01

The United States and Russia, the two largest nuclear powers, have a special obligation to provide leadership in nuclear disarmament and in strengthening the nuclear non-proliferation regime. In the past year the two countries made an effort to restart the arms control process by concluding a new treaty that would bring their legal disarmament obligations in line with the realities of their post-cold war relationships. The process of negotiating deeper nuclear reductions in the new environment turned out to be rather difficult, since the approaches that the countries used in the past are not well suited to dealing with issues like conversion of strategic nuclear delivery systems to conventional missions, tactical nuclear weapons, or dismantlement of nuclear warheads. This presentation considers the recent progress in U.S.-Russian arms control process and outlines the key issues at the negotiations. It also considers prospects for further progress in bilateral nuclear disarmament and issues that will be encountered at later stages of the process. The author argues that success of the arms reductions will depend on whether the United States and Russia will be able to build an institutional framework for cooperation on a range of issues - from traditional arms control to securing nuclear materials and from missile defense to strengthening the international nuclear safeguards. )

Differential S-phase progression after irradiation of p53 functional versus non-functional tumour cells

PubMed Central

Zölzer, Friedo; Mußfeldt, Tamare; Streffer, Christian

2014-01-01

Background Many pathways seem to be involved in the regulation of the intra-S-phase checkpoint after exposure to ionizing radiation, but the role of p53 has proven to be rather elusive. Here we have a closer look at the progression of irradiated cells through S-phase in dependence of their p53 status. Materials and methods. Three pairs of tumour cell lines were used, each consisting of one p53 functional and one p53 non-functional line. Cells were labelled with bromodeoxyuridine(BrdU) immediately after irradiation, they were then incubated in label-free medium, and at different times afterwards their position within the S-phase was determined by means of flow cytometry. Results While in the p53 deficient cells progression through S-phase was slowed significantly over at least a few hours, it was halted for just about an hour in the p53 proficient cells and then proceeded without further delay or even at a slightly accelerated pace. Conclusions It is clear from the experiments presented here that p53 does play a role for the progress of cells through the S-phase after X-ray exposure, but the exact mechanisms by which replicon initiation and elongation is controlled in irradiated cells remain to be elucidated. PMID:25435848

Efficacy and safety of a herbo-mineral ayurvedic formulation ‘Afrodet Plus®’ in male rats

PubMed Central

Dhumal, Rohit; Vijaykumar, Tushara; Dighe, Vikas; Selkar, Nilakash; Chawda, Mukesh; Vahlia, Mahesh; Vanage, Geeta

2013-01-01

Background: Reverse pharmacology for drug development has been highly productive and cost-effective in recent past as it is based on the documented therapeutic effects of plants in ancient texts. Afrodet Plus® is formulated for the treatment of male infertility, which contains ancient herbo-minerals. Its efficacy and safety are validated through this animal study in reverse pharmacology mode. Objectives: This study was undertaken to evaluate efficacy and safety of an Ayurvedic formulation Afrodet Plus® in adult male rats. Materials and Methods: Twelve male rats (Holtzman) between 8 and 10 weeks of age were randomly selected and animals were assigned to a control and two treatment groups. Dosing was performed daily. Various parameters such as weekly body weight, hematology, serum testosterone levels, epididymal sperm count, and efficiency of Daily Sperm Production (DSP) were evaluated. Results: It was found that epididymal sperm count had significantly increased in both low-dose (+27.39%) and high-dose (+40.5%) groups as compared to control group. The DSP also showed an increase of 43.7% at high dose of 180 mg/kg body weight as compared to the control group. An increase in sperm motility and especially progressive motility was observed when evaluated by Computer Assisted Semen Analyzer. Histological evaluation of testicular tissue for spermatogenic index revealed that the index had increased in treatment group as compared to control group. Conclusion: This study revealed that oral administration of Afrodet Plus® resulted in significant increase in DSP in the testis along with increase in epididymal sperm count and progressive motility as compared to control group without producing any treatment-related adverse effects. These findings provide the documentary evidence that the use of Afrodet Plus® at 90 and 180 mg/kg body weight is effective and safe for the treatment of male infertility especially to improve sperm count and progressive motility. PMID:24250145

Silent Corticotroph Adenomas After Stereotactic Radiosurgery: A Case–Control Study

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

Xu, Zhiyuan; Ellis, Scott; Lee, Cheng-Chia

Purpose: To investigate the safety and effectiveness of stereotactic radiosurgery (SRS) in patients with a silent corticotroph adenoma (SCA) compared with patients with other subtypes of non–adrenocorticotropic hormone staining nonfunctioning pituitary adenoma (NFA). Methods and Materials: The clinical features and outcomes of 104 NFA patients treated with SRS in our center between September 1994 and August 2012 were evaluated. Among them, 34 consecutive patients with a confirmatory SCA were identified. A control group of 70 patients with other subtypes of NFA were selected for review based on comparable baseline features, including sex, age at the time of SRS, tumor size, marginmore » radiation dose to the tumor, and duration of follow-up. Results: The median follow-up after SRS was 56 months (range, 6-200 months). No patients with an SCA developed Cushing disease during the follow-up. Tumor control was achieved in 21 of 34 patients (62%) in the SCA group, compared with 65 of 70 patients (93%) in the NFA group. The median progression-free survival (PFS) was 58 months in the SCA group. The actuarial PFS was 73%, 46%, and 31% in the SCA group and was 94%, 87%, and 87% in the NFA group at 3, 5, and 8 years, respectively. Silent corticotroph adenomas treated with a dose of ≥17 Gy exhibited improved PFS. New-onset loss of pituitary function developed in 10 patients (29%) in the SCA group, whereas it occurred in 18 patients (26%) in the NFA group. Eight patients (24%) in the SCA group experienced worsening of a visual field deficit or visual acuity attributed to the tumor progression, as did 6 patients (9%) in the NFA group. Conclusion: Silent corticotroph adenomas exhibited a more aggressive course with a higher progression rate than other subtypes of NFAs. Stereotactic radiosurgery is an important adjuvant treatment for control of tumor growth. Increased radiation dose may lead to improved tumor control in SCA patients.« less

Materials and Molecular Research Division annual report 1983

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

Searcy, A.W.; Muller, R.H.; Peterson, C.V.

1984-07-01

Progress is reported in the following fields: materials sciences (metallurgy and ceramics, solid-state physics, materials chemistry), chemical sciences (fundamental interactions, processes and techniques), actinide chemistry, fossil energy, electrochemical energy storage systems, superconducting magnets, semiconductor materials and devices, and work for others. (DLC)

Too easily lead? Health effects of gasoline additives.

PubMed Central

Menkes, D B; Fawcett, J P

1997-01-01

Octane-enhancing constituents of gasoline pose a number of health hazards. This paper considers the relative risks of metallic (lead, manganese), aromatic (e.g., benzene), and oxygenated additives in both industrialized and developing countries. Technological advances, particularly in industrialized countries, have allowed the progressive removal of lead from gasoline and the increased control of exhaust emissions. The developing world, by contrast, has relatively lax environmental standards and faces serious public health problems from vehicle exhaust and the rapid increase in automobile use. Financial obstacles to the modernization of refineries and vehicle fleets compound this problem and the developing world continues to import large quantities of lead additives and other hazardous materials. Progress in decreasing environmental health problems depends both on the adoption of international public health standards as well as efforts to decrease dependence on the private automobile for urban transport. Images Figure 1. Figure 2. PMID:9171982

Colloids in food: ingredients, structure, and stability.

PubMed

Dickinson, Eric

2015-01-01

This article reviews progress in the field of food colloids with particular emphasis on advances in novel functional ingredients and nanoscale structuring. Specific aspects of ingredient development described here are the stabilization of bubbles and foams by the protein hydrophobin, the emulsifying characteristics of Maillard-type protein-polysaccharide conjugates, the structural and functional properties of protein fibrils, and the Pickering stabilization of dispersed droplets by food-grade nanoparticles and microparticles. Building on advances in the nanoscience of biological materials, the application of structural design principles to the fabrication of edible colloids is leading to progress in the fabrication of functional dispersed systems-multilayer interfaces, multiple emulsions, and gel-like emulsions. The associated physicochemical insight is contributing to our mechanistic understanding of oral processing and textural perception of food systems and to the development of colloid-based strategies to control delivery of nutrients during food digestion within the human gastrointestinal tract.

Component technology for space power systems

NASA Technical Reports Server (NTRS)

Finke, R.

1982-01-01

The Lewis/OAST program for the development of Component Technology for Space Power Systems is described. The program is divided into five generic areas: semiconductor devices (transistors, thyristors, and diodes); conductors (materials and transmission lines); dielectrics; magnetic devices; and thermal control devices. Examples of progress in each of the five areas is discussed. Bipolar power transistors up to 1000 V at 100 A with a gain of 10 and a 0.5 mu sec rise and fall time are presented. A new class of semiconductor devices with a possibility of switching 1000 000 V is described. Several 100 kW rotary power transformer designs and a 25 kW, 20 kHz transformer weighting 3.2 kg have been developed. Progress on the creation of diamond-like films for thermal devices and intercalated carbon fibers with the strength of steel and the conductivity of copper at one third the mass of copper is presented.

Quality characteristics of bread produced from wheat, rice and maize flours.

PubMed

Rai, Sweta; Kaur, Amarjeet; Singh, Baljit; Minhas, K S

2012-12-01

Rice (Oryza sativa) flour and maize (Zea mays) meal substitution in wheat (Triticum aestivum) flour, from 0 to 100% each, for the production of bread was investigated. The proximate analysis, pasting properties, bread making qualities of raw materials and sensory evaluation of the bread samples were determined. The pasting temperature increased with increased percentage of rice flour and maize meal. But the other pasting characters decreased with the higher proportion of rice flour. The baking absorption was observed to increase with higher level of maize meal but it decreased when level of rice flour was increased. Loaf weight (g) decreased with progressive increase in the proportion of maize meal but increased when rice flour incorporation was increased. Loaf volume, loaf height and specific volume decreased for progressively higher level of maize meal and rice flour. The sensory evaluation revealed that 25% replacement of wheat flour was found to be more acceptable than control sample.

Doped Organic Transistors.

PubMed

Lüssem, Björn; Keum, Chang-Min; Kasemann, Daniel; Naab, Ben; Bao, Zhenan; Leo, Karl

2016-11-23

Organic field-effect transistors hold the promise of enabling low-cost and flexible electronics. Following its success in organic optoelectronics, the organic doping technology is also used increasingly in organic field-effect transistors. Doping not only increases device performance, but it also provides a way to fine-control the transistor behavior, to develop new transistor concepts, and even improve the stability of organic transistors. This Review summarizes the latest progress made in the understanding of the doping technology and its application to organic transistors. It presents the most successful doping models and an overview of the wide variety of materials used as dopants. Further, the influence of doping on charge transport in the most relevant polycrystalline organic semiconductors is reviewed, and a concise overview on the influence of doping on transistor behavior and performance is given. In particular, recent progress in the understanding of contact doping and channel doping is summarized.

Intralaminar and Interlaminar Progressive Failure Analysis of Composite Panels with Circular Cutouts

NASA Technical Reports Server (NTRS)

Goyal, Vinay K.; Jaunky, Navin; Johnson, Eric R.; Ambur, Damodar

2002-01-01

A progressive failure methodology is developed and demonstrated to simulate the initiation and material degradation of a laminated panel due to intralaminar and interlaminar failures. Initiation of intralaminar failure can be by a matrix-cracking mode, a fiber-matrix shear mode, and a fiber failure mode. Subsequent material degradation is modeled using damage parameters for each mode to selectively reduce lamina material properties. The interlaminar failure mechanism such as delamination is simulated by positioning interface elements between adjacent sublaminates. A nonlinear constitutive law is postulated for the interface element that accounts for a multi-axial stress criteria to detect the initiation of delamination, a mixed-mode fracture criteria for delamination progression, and a damage parameter to prevent restoration of a previous cohesive state. The methodology is validated using experimental data available in the literature on the response and failure of quasi-isotropic panels with centrally located circular cutouts loaded into the postbuckling regime. Very good agreement between the progressive failure analyses and the experimental results is achieved if the failure analyses includes the interaction of intralaminar and interlaminar failures.

Cariostatic effect of fluoride-containing restorative materials associated with fluoride gels on root dentin

PubMed Central

BORGES, Fernanda Tavares; CAMPOS, Wagner Reis da Costa; MUNARI, Lais Sant'ana; MOREIRA, Allyson Nogueira; PAIVA, Saul Martins; MAGALHÃES, Claudia Silami

2010-01-01

Secondary caries is still the main cause of restoration replacement, especially on the root surface Objective This in vitro study evaluated the cariostatic effects of fluoride-containing restorative materials associated with fluoride gels, on root dentin. Materials and Methods A randomized complete block design was used to test the effects of the restorative systems, fluoride regimes and the interactions among them at different distances from restoration margins. Standardized cavities were prepared on 240 bovine root specimens and randomly assigned to 15 groups of treatments (n=16). Cavities were filled with the following restorative materials: Ketac-Fil (3M-ESPE); Vitremer (3M-ESPE); Dyract/Prime & Bond NT (Dentsply); Charisma/Gluma One Bond (Heraeus Kulzer) and the control, Z250/Single Bond (3M-ESPE). The specimens were subjected to a pH-cycling model designed to simulate highcaries activity. During the cycles, 1.23% acidulated phosphate fluoride, 2.0% neutral sodium fluoride or deionized/distilled water (control) was applied to the specimens for 4 min. The surface Knoop microhardness test was performed before (KHNi) and after (KHNf) the pH cycles at 100, 200 and 300 mm from the margins. Dentin microhardness loss was represented by the difference in initial and final values (KHNi - KHNf). Data were analyzed by Friedman's and Wilcoxon's tests, ANOVA and Tukey's test (α=5%). Results The interaction of restorative systems and topical treatments was not significant (p=0.102). Dentin microhardness loss was lowest closer to the restoration. Ketac-fil presented the highest cariostatic effect. Vitremer presented a moderate effect, while Dyract and Charisma did not differ from the control, Z250. The effects of neutral and acidulated fluoride gels were similar to each other and higher than the control. Conclusion Conventional and resin-modified glass ionomer cements as well as neutral and acidulated fluoride gels inhibit the progression of artificial caries adjacent to restorations. The associated effect of fluoride-containing restorative materials and gels could not be demonstrated. PMID:21085800

Metals and Ceramics Division progress report for period ending June 30, 1984

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

Brogden, I.

1984-09-01

This progress report covers the research and development activities of the Metals and Ceramics Division from January 1, 1983, through June 30, 1984. The format of the report follows the organizational structure of the division. Short summaries of technical work in progress in the various experimental groups are presented in six parts. Chapter 1 deals with the research and development activities of the Engineering Materials Section, Chapter 2 with the Processing Science and Technology Section, Chapter 3 with the Materials Science Section, Chapter 4 with Project Activities, Chapter 5 with Specialized Research Facilities and Equipment, and Chapter 6 with Miscellaneousmore » Activities.« less

Recent progress of dopant-free organic hole-transporting materials in perovskite solar cells

NASA Astrophysics Data System (ADS)

Dongxue, Liu; Liu, Yongsheng

2017-01-01

Organic-inorganic hybrid perovskite solar cells have undergone especially intense research and transformation over the past seven years due to their enormous progress in conversion efficiencies. In this perspective, we review the latest developments of conventional perovskite solar cells with a main focus on dopant-free organic hole transporting materials (HTMs). Regarding the rapid progress of perovskite solar cells, stability of devices using dopant-free HTMs are also discussed to help readers understand the challenges and opportunities in high performance and stable perovskite solar cells. Project supported by the Scientific Research Starting Foundation for Overseas Introduced Talents of College of Chemistry, Nankai University.

Current advances in lanthanide ion (Ln(3+))-based upconversion nanomaterials for drug delivery.

PubMed

Yang, Dongmei; Ma, Ping'an; Hou, Zhiyou; Cheng, Ziyong; Li, Chunxia; Lin, Jun

2015-03-21

Lanthanide ion (Ln(3+))-based upconversion nano/micromaterials that emit higher-energy visible light when excited by low-energy NIR light have aroused considerable attention in the forefront of materials science and biomedical fields, which stems from their unique optical and chemical properties including minimum photodamage to living organisms, low autofluorescence, high signal-to-noise ratio and detection sensitivity, and high penetration depth in biological or environmental samples. Thus, Ln(3+)-based upconversion materials are rising new stars and are quickly emerging as potential candidates to revolutionize novel biomedical applications. In this review article, we mainly focus on the recent progress in various chemical syntheses of Ln(3+)-based upconversion nanomaterials, with special emphasis on their application in stimuli-response controlled drug release and subsequent therapy. Functional groups that are introduced into the stimuli-responsive system can respond to external triggers, such as pH, temperature, light, and even magnetic fields, which can regulate the movement of the pharmaceutical cargo and release the drug at a desired time and in a desired area. This is crucial to boost drug efficacy in cancer treatment while minimizing the side effects of cytotoxic drugs. Many multifunctional (magnetic/upconversion luminescence and porous) composite materials based on Ln(3+) have been designed for controlled drug delivery and multimodal bioimaging. Finally, the challenges and future opportunities for Ln(3+)-based upconversion materials are discussed.

Intelligent robots for planetary exploration and construction

NASA Technical Reports Server (NTRS)

Albus, James S.

1992-01-01

Robots capable of practical applications in planetary exploration and construction will require realtime sensory-interactive goal-directed control systems. A reference model architecture based on the NIST Real-time Control System (RCS) for real-time intelligent control systems is suggested. RCS partitions the control problem into four basic elements: behavior generation (or task decomposition), world modeling, sensory processing, and value judgment. It clusters these elements into computational nodes that have responsibility for specific subsystems, and arranges these nodes in hierarchical layers such that each layer has characteristic functionality and timing. Planetary exploration robots should have mobility systems that can safely maneuver over rough surfaces at high speeds. Walking machines and wheeled vehicles with dynamic suspensions are candidates. The technology of sensing and sensory processing has progressed to the point where real-time autonomous path planning and obstacle avoidance behavior is feasible. Map-based navigation systems will support long-range mobility goals and plans. Planetary construction robots must have high strength-to-weight ratios for lifting and positioning tools and materials in six degrees-of-freedom over large working volumes. A new generation of cable-suspended Stewart platform devices and inflatable structures are suggested for lifting and positioning materials and structures, as well as for excavation, grading, and manipulating a variety of tools and construction machinery.

Controlling Molecular Doping in Organic Semiconductors.

PubMed

Jacobs, Ian E; Moulé, Adam J

2017-11-01

The field of organic electronics thrives on the hope of enabling low-cost, solution-processed electronic devices with mechanical, optoelectronic, and chemical properties not available from inorganic semiconductors. A key to the success of these aspirations is the ability to controllably dope organic semiconductors with high spatial resolution. Here, recent progress in molecular doping of organic semiconductors is summarized, with an emphasis on solution-processed p-type doped polymeric semiconductors. Highlighted topics include how solution-processing techniques can control the distribution, diffusion, and density of dopants within the organic semiconductor, and, in turn, affect the electronic properties of the material. Research in these areas has recently intensified, thanks to advances in chemical synthesis, improved understanding of charged states in organic materials, and a focus on relating fabrication techniques to morphology. Significant disorder in these systems, along with complex interactions between doping and film morphology, is often responsible for charge trapping and low doping efficiency. However, the strong coupling between doping, solubility, and morphology can be harnessed to control crystallinity, create doping gradients, and pattern polymers. These breakthroughs suggest a role for molecular doping not only in device function but also in fabrication-applications beyond those directly analogous to inorganic doping. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Control of molten salt corrosion of fusion structural materials by metallic beryllium

NASA Astrophysics Data System (ADS)

Calderoni, P.; Sharpe, P.; Nishimura, H.; Terai, T.

2009-04-01

A series of tests have been performed between 2001 and 2006 at the Safety and Tritium Applied Research facility of the Idaho National Laboratory to demonstrate chemical compatibility between the molten salt flibe (2LiF + BeF 2 in moles) and fusion structural materials once suitable fluoride potential control methods are established. The tests adopted metallic beryllium contact as main fluoride potential control, and the results have been published in recent years. A further step was to expose two specimens of low activation ferritic/martensitic steel 9Cr-2W to static corrosion tests that include an active corrosion agent (hydrofluoric gas) in controlled conditions at 530 °C, and the results of the tests are presented in this paper. The results confirmed the expected correlation of the HF recovery with the concentration of metallic impurities dissolved in the salt because of specimen corrosion. The metals concentration dropped to levels close to the detectable limit when the beryllium rod was inserted and increased once the content of excess beryllium in the system had been consumed by HF reduction and specimen corrosion progressed. Metallographic analysis of the samples after 500 h exposure in reactive conditions showed evidence of the formation of unstable chromium oxide layers on the specimen's surface.

Control of molten salt corrosion of fusion structural materials by metallic beryllium

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

P. Calderoni; P. Sharpe; H. Nishimura

2009-04-01

A series of tests have been performed between 2001 and 2006 at the Safety and Tritium Applied Research facility of the Idaho National Laboratory to demonstrate chemical compatibility between the molten salt flibe (2LiF+BeF2 in moles) and fusion structural materials once suitable fluoride potential control methods are established. The tests adopted metallic beryllium contact as main fluoride potential control, and the results have been published in recent years. A further step was to expose two specimens of low activation ferritic/martensitic steel 9Cr-2W to static corrosion tests that include an active corrosion agent (hydrofluoric gas) in controlled conditions at 530 C,more » and the results of the tests are presented in this paper. The results confirmed the expected correlation of the HF recovery with the concentration of metallic impurities dissolved in the salt because of specimen corrosion. The metals concentration dropped to level close to the detectable limit when the beryllium rod was inserted and increased once the content of excess beryllium in the system had been consumed by HF reduction and specimens corrosion progressed. Metallographic analysis of the samples after 500 hours exposure in reactive conditions showed evidence of the formation of unstable chromium oxide layers on the specimens surface.« less

On the Development of a Unique Arc Jet Test Apparatus for Control Surface Seal Evaluations

NASA Technical Reports Server (NTRS)

Finkbeiner, Joshua R.; Dunlap, Patrick H., Jr.; Steinetz, Bruce M.; Robbie, Malcolm; Baker, Gus; Erker, Arthur

2004-01-01

NASA Glenn has developed a unique test apparatus capable of evaluating control surface seal and flap designs under simulated reentry heating conditions in NASA Johnson's arc jet test facility. The test apparatus is capable of testing a variety of seal designs with a variety of control surface materials and designs using modular components. The flap angle can be varied during testing, allowing modification of the seal environment while testing is in progress. The flap angle is varied using an innovative transmission system which limits heat transfer from the hot flap structure to the motor, all while keeping the components properly aligned regardless of thermal expansion. A combination of active and passive cooling is employed to prevent thermal damage to the test fixture while still obtaining the target seal temperature.

Silicon carbide, an emerging high temperature semiconductor

NASA Technical Reports Server (NTRS)

Matus, Lawrence G.; Powell, J. Anthony

1991-01-01

In recent years, the aerospace propulsion and space power communities have expressed a growing need for electronic devices that are capable of sustained high temperature operation. Applications for high temperature electronic devices include development instrumentation within engines, engine control, and condition monitoring systems, and power conditioning and control systems for space platforms and satellites. Other earth-based applications include deep-well drilling instrumentation, nuclear reactor instrumentation and control, and automotive sensors. To meet the needs of these applications, the High Temperature Electronics Program at the Lewis Research Center is developing silicon carbide (SiC) as a high temperature semiconductor material. Research is focussed on developing the crystal growth, characterization, and device fabrication technologies necessary to produce a family of silicon carbide electronic devices and integrated sensors. The progress made in developing silicon carbide is presented, and the challenges that lie ahead are discussed.

New protocol for synthesis of new nanomaterials with continuous 3D networks

NASA Astrophysics Data System (ADS)

Wang, Haiwang; Zhu, Ying; Wei, Xinfang; Chen, Huanhuan; Wang, Ruijie; Zhang, Dong; Song, Huaihe; Song, Shengju

2014-05-01

Nanostructured materials are attractive to researchers because of their unique optical, magnetic, thermodynamic, electrical, mechanical, and chemical properties. Controlling the morphology of nanomaterials could provide structural systems for a wide range of technologies. As a result, the development of nanofabrication techniques that are convenient and offer design flexibility is the subject of many studies. In order to progress beyond the conventional morphologies, we have turned to hydrogels, which can serve as organic templates for nanoscale objects with continuous microstructures. Transmission electron microscopy showed that the obtained nanonetwork had a continuous microstructure, which was several microns in length and width, with a cross-sectional diameter of 5-10 nm synthesized from a 35-g hexamethylenetetramine solution and a 1.5 g Zn(NO3)2 solution, and the cross-sectional diameter can be adjusted from 5 to 200 nm by controlling the concentration of the Zn(NO3)2 solution. Our results also showed that the nanostructures based on a superabsorbent polymer template could be controlled easily in terms of size and morphology by changing the concentration of the reaction solution. This protocol could be easily extended to synthesize a variety of nanostructured materials with novel morphologies.

Progress in SiC/SiC Ceramic Composite Development for Gas Turbine Hot-Section Components under NASA EPM and UEET Programs

NASA Technical Reports Server (NTRS)

DiCarlo, J. A.; Yun, Hee Mann; Morscher, Gregory N.; Bhatt, Ramakrishna T.

2002-01-01

The successful application of ceramic matrix composites as hot-section components in advanced gas turbine engines will require the development of constituent materials and processes that can provide the material systems with the key thermostructural properties required for long-term component service. Much initial progress in identifying these materials and processes was made under the former NASA Enabling Propulsion Materials Program using stoichiometric Sylramic (trademark) silicon-carbide (SiC) fibers, 2D (two dimensional)-woven fiber architectures, chemically vapor-infiltrated (CVI) BN fiber coatings (interphases), and SiC-based matrices containing CVI SiC interphase over-coatings, slurry-infiltrated SiC particulate, and melt-infiltrated (MI) silicon. The objective of this paper is to discuss the property benefits of this SiC/SiC composite system for high-temperature engine components and to elaborate on further progress in SiC/SiC development made under the new NASA Ultra Efficient Engine Technology Program. This progress stems from the recent development of advanced constituent materials and manufacturing processes, including specific treatments at NASA that improve the creep, rupture, and environmental resistance of the Sylramic fiber as well as the thermal conductivity and creep resistance of the CVI SiC over-coatings. Also discussed are recent observations concerning the detrimental effects of inadvertent carbon in the fiber-BN interfacial region and the beneficial effects of certain 2D-architectures for thin-walled SiC/SiC panels.

Recent Progress in the Design of Advanced Cathode Materials and Battery Models for High-Performance Lithium-X (X = O2 , S, Se, Te, I2 , Br2 ) Batteries.

PubMed

Xu, Jiantie; Ma, Jianmin; Fan, Qinghua; Guo, Shaojun; Dou, Shixue

2017-07-01

Recent advances and achievements in emerging Li-X (X = O 2 , S, Se, Te, I 2 , Br 2 ) batteries with promising cathode materials open up new opportunities for the development of high-performance lithium-ion battery alternatives. In this review, we focus on an overview of recent important progress in the design of advanced cathode materials and battery models for developing high-performance Li-X (X = O 2 , S, Se, Te, I 2 , Br 2 ) batteries. We start with a brief introduction to explain why Li-X batteries are important for future renewable energy devices. Then, we summarize the existing drawbacks, major progress and emerging challenges in the development of cathode materials for Li-O 2 (S) batteries. In terms of the emerging Li-X (Se, Te, I 2 , Br 2 ) batteries, we systematically summarize their advantages/disadvantages and recent progress. Specifically, we review the electrochemical performance of Li-Se (Te) batteries using carbonate-/ether-based electrolytes, made with different electrode fabrication techniques, and of Li-I 2 (Br 2 ) batteries with various cell designs (e.g., dual electrolyte, all-organic electrolyte, with/without cathode-flow mode, and fuel cell/solar cell integration). Finally, the perspective on and challenges for the development of cathode materials for the promising Li-X (X = O 2 , S, Se, Te, I 2 , Br 2 ) batteries is presented. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bioinspired Materials for Controlling Ice Nucleation, Growth, and Recrystallization.

PubMed

He, Zhiyuan; Liu, Kai; Wang, Jianjun

2018-05-15

Ice formation, mainly consisting of ice nucleation, ice growth, and ice recrystallization, is ubiquitous and crucial in wide-ranging fields from cryobiology to atmospheric physics. Despite active research for more than a century, the mechanism of ice formation is still far from satisfactory. Meanwhile, nature has unique ways of controlling ice formation and can provide resourceful avenues to unravel the mechanism of ice formation. For instance, antifreeze proteins (AFPs) protect living organisms from freezing damage via controlling ice formation, for example, tuning ice nucleation, shaping ice crystals, and inhibiting ice growth and recrystallization. In addition, AFP mimics can have applications in cryopreservation of cells, tissues, and organs, food storage, and anti-icing materials. Therefore, continuous efforts have been made to understand the mechanism of AFPs and design AFP inspired materials. In this Account, we first review our recent research progress in understanding the mechanism of AFPs in controlling ice formation. A Janus effect of AFPs on ice nucleation was discovered, which was achieved via selectively tethering the ice-binding face (IBF) or the non-ice-binding face (NIBF) of AFPs to solid surfaces and investigating specifically the effect of the other face on ice nucleation. Through molecular dynamics (MD) simulation analysis, we observed ordered hexagonal ice-like water structure atop the IBF and disordered water structure atop the NIBF. Therefore, we conclude that the interfacial water plays a critical role in controlling ice formation. Next, we discuss the design and fabrication of AFP mimics with capabilities in tuning ice nucleation and controlling ice shape and growth, as well as inhibiting ice recrystallization. For example, we tuned ice nucleation via modifying solid surfaces with supercharged unfolded polypeptides (SUPs) and polyelectrolyte brushes (PBs) with different counterions. We found graphene oxide (GO) and oxidized quasi-carbon nitride quantum dots (OQCNs) had profound effects in controlling ice shape and inhibiting ice growth. We also studied the ion-specific effect on ice recrystallization inhibition (IRI) with a large variety of anions and cations. All functionalities are achieved by tuning the properties of interfacial water on these materials, which reinforces the importance of the interfacial water in controlling ice formation. Finally, we review the development of novel application-oriented materials emerging from our enhanced understanding of ice formation, for example, ultralow ice adhesion coatings with aqueous lubricating layer, cryopreservation of cells by inhibiting ice recrystallization, and two-dimensional (2D) and three-dimensional (3D) porous materials with tunable pore sizes through recrystallized ice crystal templates. This Account sheds new light on the molecular mechanism of ice formation and will inspire the design of unprecedented functional materials based on controlled ice formation.

Carbon monoxide – physiology, detection and controlled release

PubMed Central

Heinemann, Stefan H.; Hoshi, Toshinori; Westerhausen, Matthias

2014-01-01

Carbon monoxide (CO) is increasingly recognized as a cell-signalling molecule akin to nitric oxide (NO). CO has attracted particular attention as a potential therapeutic agent because of its reported anti-hypertensive, anti-inflammatory and cell-protective effects. We discuss recent progress in identifying new effector systems and elucidating the mechanisms of action of CO on, e.g., ion channels, as well as the design of novel methods to monitor CO in cellular environments. We also report on recent developments in the area of CO-releasing molecules (CORMs) and materials for controlled CO application. Novel triggers for CO release, metal carbonyls and degradation mechanisms of CORMs, are highlighted. In addition, potential formulations of CORMs for targeted CO release are discussed. PMID:24556640

Liquid rocket propulsion: Retrospective and prospects

NASA Astrophysics Data System (ADS)

Rosenberg, Sanders D.

1993-02-01

Rocket propulsion has made a fundamental contribution to change in the human condition during the second half of the 20th Century. This paper presents a survey of the basic elements of and future prospects for liquid rocket propulsion systems, with emphasis placed on their bipropellant engines, which have contributed profoundly to the successes of this 'aerospace century.' Many technologies had to reach maturity simultaneously to enable our current progress: materials, electronics, guidance and control, systems engineering, and propulsion, made major contributions. However, chemical propellants and the engine systems required to extract and control their propulsive power successfully are at the heart of all that humankind has accomplished through space flight and the use of space for the betterment of all. And it is a fascinating story to tell.

Non-adiabatic Excited State Molecule Dynamics Modeling of Photochemistry and Photophysics of Materials

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

Nelson, Tammie Renee; Tretiak, Sergei

2017-01-06

Understanding and controlling excited state dynamics lies at the heart of all our efforts to design photoactive materials with desired functionality. This tailor-design approach has become the standard for many technological applications (e.g., solar energy harvesting) including the design of organic conjugated electronic materials with applications in photovoltaic and light-emitting devices. Over the years, our team has developed efficient LANL-based codes to model the relevant photophysical processes following photoexcitation (spatial energy transfer, excitation localization/delocalization, and/or charge separation). The developed approach allows the non-radiative relaxation to be followed on up to ~10 ps timescales for large realistic molecules (hundreds of atomsmore » in size) in the realistic solvent dielectric environment. The Collective Electronic Oscillator (CEO) code is used to compute electronic excited states, and the Non-adiabatic Excited State Molecular Dynamics (NA-ESMD) code is used to follow the non-adiabatic dynamics on multiple coupled Born-Oppenheimer potential energy surfaces. Our preliminary NA-ESMD simulations have revealed key photoinduced mechanisms controlling competing interactions and relaxation pathways in complex materials, including organic conjugated polymer materials, and have provided a detailed understanding of photochemical products and intermediates and the internal conversion process during the initiation of energetic materials. This project will be using LANL-based CEO and NA-ESMD codes to model nonradiative relaxation in organic and energetic materials. The NA-ESMD and CEO codes belong to a class of electronic structure/quantum chemistry codes that require large memory, “long-queue-few-core” distribution of resources in order to make useful progress. The NA-ESMD simulations are trivially parallelizable requiring ~300 processors for up to one week runtime to reach a meaningful restart point.« less

Progression of Neurovisceral Storage Disease With Supranuclear Ophthalmoplegia Following Orthotopic Liver Transplantation

PubMed Central

Gartner, J. Carlton; Bergman, Ira; Malatack, J. Jeffrey; Zitelli, Basil J.; Jaffe, Ronald; Watkins, John B.; Shaw, Byers W.; Iwatsuki, Shunzaburo; Starzl, Thomas E.

2011-01-01

A 7-year-old girl with progressive ataxia, spasticity, supranuclear ophthalmoplegia, and sea-blue histiocytes in her bone marrow underwent orthotopic liver transplantation for hepatocellular carcinoma. After an initial period of stabilization, she has shown progression of neurologic symptoms with recurrence of storage material in the transplanted liver. PMID:2999691

Ceramic technology for advanced heat engines project. Semiannual progress report, October 1985-March 1986

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

Not Available

1986-08-01

Significant accomplishments in fabricating cermaic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DOD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, additional research is needed in materials and processing development, design methodology, and data base and life prediction. An assessment of needs was completed, and a five-year project plan was developed with extensive input from private industry. The objective of the project is to develop the industrial technology base required for reliable ceramics for application in advanced automotivemore » heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. although this is a generic materials project, the focus is on structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines.« less

40 CFR 52.2037 - Control strategy plans for attainment and rate-of-progress: Ozone.

Code of Federal Regulations, 2014 CFR

2014-07-01

... and rate-of-progress: Ozone. 52.2037 Section 52.2037 Protection of Environment ENVIRONMENTAL... (CONTINUED) Pennsylvania § 52.2037 Control strategy plans for attainment and rate-of-progress: Ozone. (a... ozone nonattainment area has attained the ozone standard and that the reasonable further progress and...

DOE research and development report. Progress report, October 1980-September 1981

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

Bingham, Carleton D.

The DOE New Brunswick Laboratory (NBL) is the US Government's Nuclear Materials Standards and Measurement Laboratory. NBL is assigned the mission to provide and maintain, as an essential part of federal statutory responsibilities related to national and international safeguards of nuclear materials for USA defense and energy programs, an ongoing capability for: the development, preparation, certification, and distribution of reference materials for the calibration and standardization of nuclear materials measurements; the development, improvement, and evaluation of nuclear materials measurement technology; the assessment and evaluation of the practice and application of nuclear materials measurement technology; expert and reliable specialized nuclear materialsmore » measurement services for the government; and technology exchange and training in nuclear materials measurement and standards. Progress reports for this fiscal year are presented under the following sections: (1) development or evaluation of measurement technology (elemental assay of uranium plutonium; isotope composition); (2) standards and reference materials (NBL standards and reference materials; NBS reference materials); and (3) evaluation programs (safeguards analytical laboratory evaluation; general analytical evaluation program; other evaluation programs).« less

Silk-elastin-like protein biomaterials for the controlled delivery of therapeutics.

PubMed

Huang, Wenwen; Rollett, Alexandra; Kaplan, David L

2015-05-01

Genetically engineered biomaterials are useful for controlled delivery owing to their rational design, tunable structure-function, biocompatibility, degradability and target specificity. Silk-elastin-like proteins (SELPs), a family of genetically engineered recombinant protein polymers, possess these properties. Additionally, given the benefits of combining semi-crystalline silk-blocks and elastomeric elastin-blocks, SELPs possess multi-stimuli-responsive properties and tunability, thereby becoming promising candidates for targeted cancer therapeutics delivery and controlled gene release. An overview of SELP biomaterials for drug delivery and gene release is provided. Biosynthetic strategies used for SELP production, fundamental physicochemical properties and self-assembly mechanisms are discussed. The review focuses on sequence-structure-function relationships, stimuli-responsive features and current and potential drug delivery applications. The tunable material properties allow SELPs to be pursued as promising biomaterials for nanocarriers and injectable drug release systems. Current applications of SELPs have focused on thermally-triggered biomaterial formats for the delivery of therapeutics, based on local hyperthermia in tumors or infections. Other prominent controlled release applications of SELPs as injectable hydrogels for gene release have also been pursued. Further biomedical applications that utilize other stimuli to trigger the reversible material responses of SELPs for targeted delivery, including pH, ionic strength, redox, enzymatic stimuli and electric field, are in progress. Exploiting these additional stimuli-responsive features will provide a broader range of functional biomaterials for controlled therapeutics release and tissue regeneration.

Aliphatic and aromatic plant biopolymer dynamics in soil particles isolated from sequential density fractionation

NASA Astrophysics Data System (ADS)

Caldwell, B.; Filley, T.; Sollins, P.; Lajtha, K.; Swanston, C.; Kleber, M.; Kramer, M.

2007-12-01

A recent multi-layer-based soil organic matter-mineral interaction mechanistic model to describe the nature of soil organic matter-mineral surface mechanism for soil organic matter stabilization predicts that proteinaceous and aliphatic materials establish the core of strong binding-interactions upon which other organic matter is layered. A key methodology providing data underpinning this hypothesis is sequential density fractionation where soil is partitioned into particles of increasing density with the assumption that a partial control on organic matter distribution through density series is the thickness of its layering. Four soils of varying mineralogy and texture were investigated for their biopolymer, isotopic, and mineralogical properties. Light fractions (<1.8 g/cm3), although dominanted by organic detritus, did not always contain the highest concentration of lignin and substituted fatty acids from cutin and suberin while heavier fractions, 1.8-2.6 g/cm3, exhibited a progressive decrease in concentration in plant derived biopolymers with density. Extractable lignin phenols exhibited a progressive oxidation state with density. The concentration of biopolymers roughly mirrored the C:N ratio of soil particles which dropped consistently with increasing particle density. Although, in all soils, both lignin phenols and SFA concentration generally decreased with increasing density the ratio SFA/lignin varied with density and depending upon the soil. All soils, except the oxisol, exhibited an increase in SFA with respect to lignin suggesting a selective stabilization of those material with respect to lignin. In the oxisol, which showed little variation in its hematite dominated mineralogy across density, SFA/lignin remained constant, potentially indicating a greater capacity to stabilize lignin in that system. Interestingly, the lignin oxidation state increased with density in the oxisol. Given the variation in soil character, the consistency in these trends it suggests a general phenomenon of progressive decay in plant derived material with thinness of mineral coating but an overall relative increase in aliphatic character-all consistent with the multi-layer model.

Protein Mediated Oxidative Stress in Patients with Diabetes and its Associated Neuropathy: Correlation with Protein Carbonylation and Disease Activity Markers

PubMed Central

Almogbel, Ebtehal

2017-01-01

Introduction Free radicals have been implicated as Diabetes Mellitus (DM) contributors in type 2 DM and its associated Diabetes Mellitus Neuropathy (DMN). However, the potential for protein mediated oxidative stress to contribute disease pathogenesis remains largely unexplored. Aim To investigate the status and contribution of protein mediated oxidative stress in patients with DM or DMN and to explore whether oxidative protein modification has a role in DM progression to DM associated neuropathy. Materials and Methods Sera from 42 DM and 37 DMN patients with varying levels of disease activities biomarkers (HbA1C, patients’ age or disease duration) and 21 age- and sex-matched healthy controls were evaluated for serum levels of protein mediated oxidative stress. Results Serum analysis showed significantly higher levels of protein carbonyl contents in both DM and DMN patients compared with healthy controls. Importantly, not only was there an increased number of subjects positive for protein carbonylation, but also the levels of protein carbonyl contents were significantly higher among DM and DMN patients, whose HbA1C were ≥8.8 as compared with patients with lower HbA1C (HbA1C<8.8). Similar pattern of protein carbonyls formation was also observed with patients’ ages or with patient’s disease durations, suggesting a possible relationship between protein oxidation and disease progression. Furthermore, sera from DMN patients had higher levels of protein carbonylation compared with non-neuropathic DM patients’ sera, suggesting an involvement of protein oxidation in the progression of diabetes to diabetes neuropathy. Conclusion These findings support an association between protein oxidation and DM or DMN progression. The stronger response observed in patients with higher HbA1C or patients’ ages or disease durations suggests, that protein mediated oxidative stress may be useful in evaluating the progression of DM and its associated DMN and in elucidating the mechanisms of these disorders pathogenesis. PMID:28384853

Proton Therapy for Reirradiation of Progressive or Recurrent Chordoma

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

McDonald, Mark W., E-mail: mmcdona2@iuhealth.org; Indiana University Health Proton Therapy Center, Bloomington, Indiana; Linton, Okechuckwu R.

2013-12-01

Purpose: To report the results in patients reirradiated with proton therapy for recurrent or progressive chordoma, with or without salvage surgery. Methods and Materials: A retrospective review of 16 consecutive patients treated from 2005 to 2012 was performed. All patients had received at least 1 prior course of radiation therapy to the same area, and all but 1 patient had at least 1 surgical resection for disease before receiving reirradiation. At the time of recurrence or progression, half of the patients underwent additional salvage surgery before receiving reirradiation. The median prior dose of radiation was 75.2 Gy (range, 40-79.2 Gy).more » Six patients had received prior proton therapy, and the remainder had received photon radiation. The median gross tumor volume at the time of reirradiation was 71 cm{sup 3} (range, 0-701 cm{sup 3}). Reirradiation occurred at a median interval of 37 months after prior radiation (range, 12-129 months), and the median dose of reirradiation was 75.6 Gy (relative biological effectiveness [RBE]) (range. 71.2-79.2 Gy [RBE]), given in standard daily fractionation (n=14) or hyperfractionation (n=2). Results: The median follow-up time was 23 months (range, 6-63 months); it was 26 months in patients alive at the last follow-up visit (range, 12-63 months). The 2-year estimate for local control was 85%, overall survival 80%, chordoma-specific survival 88%, and development of distant metastases 20%. Four patients have had local progression: 3 in-field and 1 marginal. Late toxicity included grade 3 bitemporal lobe radionecrosis in 1 patient that improved with hyperbaric oxygen, a grade 4 cerebrospinal fluid leak with meningitis in 1 patient, and a grade 4 ischemic brainstem stroke (out of radiation field) in 1 patient, with subsequent neurologic recovery. Conclusions: Full-dose proton reirradiation provided encouraging initial disease control and overall survival for patients with recurrent or progressive chordoma, although additional toxicities may develop with longer follow-up times.« less

Damage Progression in Buckle-Resistant Notched Composite Plates Loaded in Uniaxial Compression

NASA Technical Reports Server (NTRS)

McGowan, David M.; Davila, Carlos G.; Ambur, Damodar R.

2001-01-01

Results of an experimental and analytical evaluation of damage progression in three stitched composite plates containing an angled central notch and subjected to compression loading are presented. Parametric studies were conducted systematically to identify the relative effects of the material strength parameters on damage initiation and growth. Comparisons with experiments were conducted to determine the appropriate in situ values of strengths for progressive failure analysis. These parametric studies indicated that the in situ value of the fiber buckling strength is the most important parameter in the prediction of damage initiation and growth in these notched composite plates. Analyses of the damage progression in the notched, compression-loaded plates were conducted using in situ material strengths. Comparisons of results obtained from these analyses with experimental results for displacements and axial strains show good agreement.

Penile enhancement using autologous tissue engineering with biodegradable scaffold: a clinical and histomorphometric study.

PubMed

Perovic, Sava V; Sansalone, Salvatore; Djinovic, Rados; Ferlosio, Amedeo; Vespasiani, Giuseppe; Orlandi, Augusto

2010-09-01

Autologous tissue engineering with biodegradable scaffolds is a new treatment option for real penile girth enhancement. The aim of this article is to evaluate tissue remodeling after penile girth enhancement using this technique. Between June 2005 and May 2007, a group of 12 patients underwent repeated penile widening using biodegradable scaffolds enriched with expanded autologous scrotal dartos cells. Clinical monitoring was parallel to histological investigation of tissue remodeling. During second surgical procedure, biopsies were obtained 10-14 months after first surgery (mean 12 months, N=6) and compared with those obtained after 22-24 months (mean 23 months, N=6), and control biopsies from patients who underwent circumcision (N=5). Blind evaluation of histomorphometrical and immunohistochemical finding was performed in paraffin sections. Penile girth gain in a flaccid state ranged between 1.5 and 3.8 cm (mean 2.1 ± 0.28 cm) and in full erection between 1.2 and 4 cm (mean 1.9 ± 0.28 cm). Patients' satisfaction, defined by a questionnaire, was good (25%) and very good (75%). In biopsies obtained 10-14 months after first surgery, highly vascularized loose tissue with collagen deposition associated with small foci of mild chronic and granulomatous inflammation surrounding residual amorphous material was observed. Fibroblast-like hyperplasia and small vessel neoangiogenesis occurred intimately associated with the progressive growth of vascular-like structures from accumulation of CD34 and alpha-smooth muscle actin-positive cells surrounding residual scaffold-like amorphous material. Capillary neoangiogenesis occurred inside residual amorphous material. In biopsies obtained after 22-24 months, inflammation almost disappeared and tissue closely resembled that of the dartos fascia of control group. Autologous tissue engineering using expanded scrotal dartos cells with biodegradable scaffolds is a new and promising method for penile widening that generates progressive accumulation of stable collagen-rich, highly vascularized tissue matrix that closely resemble deep dartos fascia. © 2009 International Society for Sexual Medicine.

Mass spectrometry of long-lived radionuclides

NASA Astrophysics Data System (ADS)

Becker, Johanna Sabine

2003-10-01

The capability of determining element concentrations at the trace and ultratrace level and isotope ratios is a main feature of inorganic mass spectrometry. The precise and accurate determination of isotope ratios of long-lived natural and artificial radionuclides is required, e.g. for their environmental monitoring and health control, for studying radionuclide migration, for age dating, for determining isotope ratios of radiogenic elements in the nuclear industry, for quality assurance and determination of the burn-up of fuel material in a nuclear power plant, for reprocessing plants, nuclear material accounting and radioactive waste control. Inorganic mass spectrometry, especially inductively coupled plasma mass spectrometry (ICP-MS) as the most important inorganic mass spectrometric technique today, possesses excellent sensitivity, precision and good accuracy for isotope ratio measurements and practically no restriction with respect to the ionization potential of the element investigated—therefore, thermal ionization mass spectrometry (TIMS), which has been used as the dominant analytical technique for precise isotope ratio measurements of long-lived radionuclides for many decades, is being replaced increasingly by ICP-MS. In the last few years instrumental progress in improving figures of merit for the determination of isotope ratio measurements of long-lived radionuclides in ICP-MS has been achieved by the application of a multiple ion collector device (MC-ICP-MS) and the introduction of the collision cell interface in order to dissociate disturbing argon-based molecular ions, to reduce the kinetic energy of ions and neutralize the disturbing noble gas ions (e.g. of 129Xe + for the determination of 129I). The review describes the state of the art and the progress of different inorganic mass spectrometric techniques such as ICP-MS, laser ablation ICP-MS vs. TIMS, glow discharge mass spectrometry, secondary ion mass spectrometry, resonance ionization mass spectrometry and accelerator mass spectrometry for the determination of long-lived radionuclides in quite different materials.

Microwave-Assisted Synthesis of Nano-materials in Aqueous

EPA Science Inventory

Whether it is termed a revolution or simply a continuous evolution, clearly development of new materials and their understanding on smaller and smaller length scale is at the root of progress in many areas of materials science.1 This is true in developing existing bulk materials...

Evaluation of caries progression in dentin treated by fluoride-containing materials using an in-air micro-PIGE and micro-PIXE measurement system

NASA Astrophysics Data System (ADS)

Yamamoto, H.; Iwami, Y.; Yagi, K.; Hayashi, M.; Komatsu, H.; Okuyama, K.; Matsuda, Y.; Yasuda, K.

2015-04-01

It is well-known that fluorine (F) is involved in the progression of caries. The evaluation of caries progression has conventionally been based on the change in mineral content using transverse microradiography (TMR). The purpose of this study was to evaluate the progression of dentinal caries by the change in calcium (Ca) content using Particle-Induced Gamma-ray Emission/Particle-Induced X-ray Emission (PIGE/PIXE) techniques at the Wakasa Wan Energy Research Center. We also assessed the relationship between caries progression rate and the concentration of F penetration into dentin from dental fluoride-containing materials (FCMs). Dentin sections of six extracted human teeth were prepared to obtain various amounts of F uptake using three types of FCMs. F and Ca distribution of specimens were obtained using PIGE/PIXE techniques. After evaluation, the specimens were immersed in 10 ml of demineralizing solution (pH 4.5) to simulate caries attack. To estimate caries progression rates, the same portions of the specimens were evaluated after caries attack treatment using PIGE/PIXE. A negative correlation between the F uptake in dentin and the rate of caries progression was observed. Therefore, caries progression in dentin was reduced by increasing the amount of F uptake from FCMs. This demonstrates that PIGE/PIXE techniques are valuable for estimating caries progression rates.

Epidemiological analysis of factors influencing rate of progress in Echinococcus granulosus control in New Zealand.

PubMed Central

Burridge, M. J.; Schwabe, C. W.

1977-01-01

The factors influencing the rate of progress in Echinococcus granulosus control in New Zealand were analysed by hydatid control area using stepwise multiple regression techniques. The results indicated that the rate of progress was related positively to initial E. granulosus prevalence in dogs and the efficiency with which local authorities implemented national control policy, and negatively to the Maori proportion in the local population and the number of dogs per owner. Problems in analysis of the New Zealand data are discussed and improved methods of monitoring progress in hydatid disease control programmes are described. Images Fig. 1 PMID:265340

25th anniversary article: a decade of organic/polymeric photovoltaic research.

PubMed

Dou, Letian; You, Jingbi; Hong, Ziruo; Xu, Zheng; Li, Gang; Street, Robert A; Yang, Yang

2013-12-10

Organic photovoltaic (OPV) technology has been developed and improved from a fancy concept with less than 1% power conversion efficiency (PCE) to over 10% PCE, particularly through the efforts in the last decade. The significant progress is the result of multidisciplinary research ranging from chemistry, material science, physics, and engineering. These efforts include the design and synthesis of novel compounds, understanding and controlling the film morphology, elucidating the device mechanisms, developing new device architectures, and improving large-scale manufacture. All of these achievements catalyzed the rapid growth of the OPV technology. This review article takes a retrospective look at the research and development of OPV, and focuses on recent advances of solution-processed materials and devices during the last decade, particular the polymer version of the materials and devices. The work in this field is exciting and OPV technology is a promising candidate for future thin film solar cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of a drug delivery system for the treatment of periodontal disease based on bioerodible poly(ortho esters).

PubMed

Roskos, K V; Fritzinger, B K; Rao, S S; Armitage, G C; Heller, J

1995-03-01

Poly(ortho esters) prepared by the condensation of 1,2,6-hexanetriol and an alkyl orthoacetate are viscous, semisolid materials at room temperature that can be injected using a blunt needle. When tetracycline was incorporated into these materials, complete release occurred within about 24 hours, but when small amounts of Mg(OH)2 were incorporated into the polymer release could be extended to many weeks, and a loading of 0.5 wt% resulted in sustained release of about 10 days. When adhesion was tested using bovine teeth, cohesive failure of the pure polymer occurred at a force of about 392 mN cm-2 and cohesive failure of a polymer incorporating 10 wt% tetracycline and 1 wt% (Mg(OH)2 occurred at about 118 mN cm-2. The combination of injectability, dentoadhesiveness and ability to control accurately the release of incorporated antibiotics makes these materials promising candidates for bioerodible delivery systems useful in the treatment of periodontitis. Toxicological studies are currently in progress.

Advances and Challenges in Metal Sulfides/Selenides for Next-Generation Rechargeable Sodium-Ion Batteries.

PubMed

Hu, Zhe; Liu, Qiannan; Chou, Shu-Lei; Dou, Shi-Xue

2017-12-01

Rechargeable sodium-ion batteries (SIBs), as the most promising alternative to commercial lithium-ion batteries, have received tremendous attention during the last decade. Among all the anode materials for SIBs, metal sulfides/selenides (MXs) have shown inspiring results because of their versatile material species and high theoretical capacity. They suffer from large volume expansion, however, which leads to bad cycling performance. Thus, methods such as carbon modification, nanosize design, electrolyte optimization, and cut-off voltage control are used to obtain enhanced performance. Here, recent progress on MXs is summarized in terms of arranging the crystal structure, synthesis methods, electrochemical performance, mechanisms, and kinetics. Challenges are presented and effective ways to solve the problems are proposed, and a perspective for future material design is also given. It is hoped that light is shed on the development of MXs to help finally find applications for next-generation rechargeable batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanotechnology in Dental Sciences: Moving towards a Finer Way of Doing Dentistry

PubMed Central

Uskoković, Vuk; Bertassoni, Luiz Eduardo

2010-01-01

Nanotechnologies are predicted to revolutionize: (a) the control over materials properties at ultrafine scales; and (b) the sensitivity of tools and devices applied in various scientific and technological fields. In this short review, we argue that dentistry will be no exception to this trend. Here, we present a dynamic view of dental tissues, an adoption of which may lead to finer, more effective and minimally invasive reparation approaches. By doing so, we aim at providing insights into some of the breakthroughs relevant to understanding the genesis of dental tissues at the nanostructural level or generating dental materials with nanoscale critical boundaries. The lineage of the progress of dental science, including the projected path along the presumed nanotechnological direction of research and clinical application is mentioned too. We conclude by claiming that dentistry should follow the trend of probing matter at nanoscale that currently dominates both materials and biological sciences in order to improve on the research strategies and clinical techniques that have traditionally rested on mechanistic assumptions. PMID:27103959

Demand controlled ventilating systems: Sensor market survey. Energy conservation in buildings and community systems programme, annex 18, December 1991

NASA Astrophysics Data System (ADS)

Raatschen, W.; Sjoegren, M.

The subject of indoor and outdoor air quality has generated a great deal of attention in many countries. Areas of concern include outgassing of building materials as well as occupant-generated pollutants such as carbon dioxide, moisture, and odors. Progress has also been made towards addressing issues relating to the air tightness of the building envelope. Indoor air quality studies indicate that better control of supply flow rates as well as the air distribution pattern within buildings are necessary. One method of maintaining good indoor air quality without extensive energy consumption is to control the ventilation rate according to the needs and demands of the occupants, or to preserve the building envelope. This is accomplished through the use of demand controlled ventilating (DCV) systems. The specific objective of Annex 18 is to develop guidelines for demand controlled ventilating systems based on state of the art analyses, case studies on ventilation effectiveness, and proposed ventilation rates for different users in domestic, office, and school buildings.

Hyperfractionated Low-Dose (21 Gy) Radiotherapy for Cranial Skeletal Metastases in Patients With High-Risk Neuroblastoma

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

Kushner, Brian H., E-mail: kushnerb@mskcc.or; Cheung, Nai-Kong V.; Barker, Christopher A.

2009-11-15

Purpose: To present a large experience (73 patients) using a standard radiotherapy (RT) protocol to prevent relapse in cranial sites where measurable metastatic neuroblastoma (NB), an adverse prognostic marker, is common. Methods and Materials: High-risk NB patients with measurable cranial disease at diagnosis or residual cranial disease after induction therapy had those sites irradiated with hyperfractionated 21 Gy; a brain-sparing technique was used for an extensive field. The patients were grouped according to the response to systemic therapy. Thus, when irradiated, Group 1 patients were in complete remission and Group 2 patients had primary refractory disease. Follow-up was from themore » start of cranial RT. Results: At 3 years, the 39 Group 1 patients had a progression-free survival rate of 51%; control of cranial disease was 79%. Two relapses involved irradiated cranial sites. Two other patients relapsed in the irradiated cranial sites 6 and 12 months after a systemic relapse. At 3 years, the 34 Group 2 patients had a progression-free survival rate of 33%; control of cranial disease was 52%. Group 2 included 19 patients who had residual cranial (with or without extracranial) disease. The cranial sites showed major (n = 13), minor (n = 2), or no response (n = 4) to RT. Five patients had progression in the cranial RT field at 10-27 months. Group 2 also included 15 patients who had persistent NB in extracranial, but not cranial, sites. Of these 15 patients, 2 relapsed in the irradiated cranial sites and elsewhere at 8 and 14 months. Cranial RT was well tolerated, with no Grade 2 or greater toxicity. Conclusion: Hyperfractionated 21-Gy cranial RT might help control NB and is feasible without significant toxicity in children.« less

Progress in materials and structures at Lewis Research Center

NASA Technical Reports Server (NTRS)

Glasgow, T. K.; Lauver, R. W.; Halford, G. R.; Davies, R. L.

1980-01-01

The development of power and propulsion system technology is discussed. Specific emphasis is placed on the following: high temperature materials; composite materials; advanced design and life prediction; and nondestructive evaluation. Future areas of research are also discussed.

[Research progress in post-fire debris flow].

PubMed

Di, Xue-ying; Tao, Yu-zhu

2013-08-01

The occurrence of the secondary disasters of forest fire has significant impacts on the environment quality and human health and safety. Post-fire debris flow is one of the most hazardous secondary disasters of forest fire. To understand the occurrence conditions of post-fire debris flow and to master its occurrence situation are the critical elements in post-fire hazard assessment. From the viewpoints of vegetation, precipitation threshold and debris flow material sources, this paper elaborated the impacts of forest fire on the debris flow, analyzed the geologic and geomorphic conditions, precipitation and slope condition that caused the post-fire debris flow as well as the primary mechanisms of debris-flow initiation caused by shallow landslide or surface runoff, and reviewed the research progress in the prediction and forecast of post-fire debris flow and the related control measures. In the future research, four aspects to be focused on were proposed, i. e., the quantification of the relationships between the fire behaviors and environmental factors and the post-fire debris flow, the quantitative research on the post-fire debris flow initiation and movement processes, the mechanistic model of post-fire debris flow, and the rapid and efficient control countermeasures of post-fire debris flow.

Kinetics of Melting and Dissolution in Lunar Materials

NASA Technical Reports Server (NTRS)

Hess, Paul C.

2002-01-01

An understanding of the petrogenesis of lunar magmas, particularly mare basalts and the parent magmas to the Mg-rich suite, remains an unfulfilled goal. The fact is not surprising given the complexity of the problem. On the Moon, the source region for lunar magmas is not primitive mantle but rather a series of cumulate rocks that vary widely in both minerology and major and minor element contents. The stratigraphy of the cumulate mantle is not likely to be very regular given that the culumate pile is formed initially in an unstable configuration and subsequent thermal and compositional heterogeneities on a number of length scales. These lithologic heterogeneities, the large range of pressures and temperatures over which melts are generated on the Moon, and the close juxtaposition of cumulate rock with widely varying solidii introduce significant complications to the nature of the melting relations that control melt generation. These factors, coupled with the likelihood that polybaric fractional melting of varying efficiencies ultimately control the composition of planetary progress, are ample reasons why the lunar magmas remain the enigma they are. To make progress, phase equilibria studies must be coupled with a detailed understanding of the time scales and the dynamics of crystal and melt reequilibration processes.

Identification of the Relationship between Oil Body Morphology and Oil Content by Microstructure Comparison Combining with QTL Analysis in Brassica napus

PubMed Central

Gu, Jianwei; Chao, Hongbo; Wang, Hao; Li, Yonghong; Li, Dianrong; Xiang, Jun; Gan, Jianping; Lu, Guangyuan; Zhang, Xuekun; Long, Yan; Li, Maoteng

2017-01-01

Oil bodies (OBs) are relatively simple but very important organelles comprising a matrix of triacylglycerol (TAG) surrounded by a phospholipid monolayer embedded and covered with unique proteins. The OB structure in Brassica napus with different oil content and the relationship between the oil content and the OB structure needs to be better understood. In this paper, the characteristics of OBs in the embryo of a series of B. napus materials with different oil content ranging from 34% to over 60% were studied. The results indicated that the OB size was significantly positively correlated with the oil content but was significantly negatively correlated with the glucosinolates and the protein content. Many genes associated with TAG synthesis, OB-membrane proteins, and the cell progress regulatory pathway were identified in the confidence interval of co-located QTLs for oil content, fatty acid (FA) compositions, and protein content. Our results suggested that the morphology of OBs might be directly controlled by the genes associated with OB-membrane proteins and indirectly controlled by the genes associated with TAG synthesis and cell progress regulatory pathway. PMID:28111582

Identification of the Relationship between Oil Body Morphology and Oil Content by Microstructure Comparison Combining with QTL Analysis in Brassica napus.

PubMed

Gu, Jianwei; Chao, Hongbo; Wang, Hao; Li, Yonghong; Li, Dianrong; Xiang, Jun; Gan, Jianping; Lu, Guangyuan; Zhang, Xuekun; Long, Yan; Li, Maoteng

2016-01-01

Oil bodies (OBs) are relatively simple but very important organelles comprising a matrix of triacylglycerol (TAG) surrounded by a phospholipid monolayer embedded and covered with unique proteins. The OB structure in Brassica napus with different oil content and the relationship between the oil content and the OB structure needs to be better understood. In this paper, the characteristics of OBs in the embryo of a series of B. napus materials with different oil content ranging from 34% to over 60% were studied. The results indicated that the OB size was significantly positively correlated with the oil content but was significantly negatively correlated with the glucosinolates and the protein content. Many genes associated with TAG synthesis, OB-membrane proteins, and the cell progress regulatory pathway were identified in the confidence interval of co-located QTLs for oil content, fatty acid (FA) compositions, and protein content. Our results suggested that the morphology of OBs might be directly controlled by the genes associated with OB-membrane proteins and indirectly controlled by the genes associated with TAG synthesis and cell progress regulatory pathway.

Comprehensive Craniospinal Radiation for Controlling Central Nervous System Leukemia

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

Walker, Gary V.; Shihadeh, Ferial; Kantarjian, Hagop

Purpose: To determine the benefit of radiation therapy (RT) in resolution of neurologic symptoms and deficits and whether the type of RT fields influences central nervous system (CNS) control in adults with CNS leukemia. Methods and Materials: A total of 163 adults from 1996 to 2012 were retrospectively analyzed. Potential associations between use of radiation and outcome were investigated by univariate and multivariate analysis. Results: The median survival time was 3.8 months after RT. Common presenting symptoms were headache in 79 patients (49%), cranial nerve VII deficit in 46 (28%), and cranial nerve II deficit in 44 (27%). RT was deliveredmore » to the base of skull in 48 patients (29%), to the whole brain (WB) in 67 (41%), and to the craniospinal axis (CS) in 48 (29%). Among 149 patients with a total of 233 deficits, resolution was observed in 34 deficits (15%), improvement in 126 deficits (54%), stability in 34 deficits (15%), and progression in 39 deficits (17%). The 12-month CNS progression-free survival was 77% among those receiving CS/WB and 51% among those receiving base of skull RT (P=.02). On multivariate analysis, patients who did not undergo stem cell transplantation after RT and base of skull RT were associated with worse CNS progression-free survival. Conclusions: Improvement or resolution of symptoms occurred in two thirds of deficits after RT. Comprehensive radiation to the WB or CS seems to offer a better outcome, especially in isolated CNS involvement.« less

Practical color vision tests for air traffic control applicants: en route center and terminal facilities.

PubMed

Mertens, H W; Milburn, N J; Collins, W E

2000-12-01

Two practical color vision tests were developed and validated for use in screening Air Traffic Control Specialist (ATCS) applicants for work at en route center or terminal facilities. The development of the tests involved careful reproduction/simulation of color-coded materials from the most demanding, safety-critical color task performed in each type of facility. The tests were evaluated using 106 subjects with normal color vision and 85 with color vision deficiency. The en route center test, named the Flight Progress Strips Test (FPST), required the identification of critical red/black coding in computer printing and handwriting on flight progress strips. The terminal option test, named the Aviation Lights Test (ALT), simulated red/green/white aircraft lights that must be identified in night ATC tower operations. Color-coding is a non-redundant source of safety-critical information in both tasks. The FPST was validated by direct comparison of responses to strip reproductions with responses to the original flight progress strips and a set of strips selected independently. Validity was high; Kappa = 0.91 with original strips as the validation criterion and 0.86 with different strips. The light point stimuli of the ALT were validated physically with a spectroradiometer. The reliabilities of the FPST and ALT were estimated with Chronbach's alpha as 0.93 and 0.98, respectively. The high job-relevance, validity, and reliability of these tests increases the effectiveness and fairness of ATCS color vision testing.

7 CFR 764.459 - Evaluation of borrower progress.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Requirements § 764.459 Evaluation of borrower progress. (a) The vendor must provide the Agency with a periodic... material and assign a score. The following table lists the possible scores, the criteria used to assign...

7 CFR 764.459 - Evaluation of borrower progress.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Requirements § 764.459 Evaluation of borrower progress. (a) The vendor must provide the Agency with a periodic... material and assign a score. The following table lists the possible scores, the criteria used to assign...

7 CFR 764.459 - Evaluation of borrower progress.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Requirements § 764.459 Evaluation of borrower progress. (a) The vendor must provide the Agency with a periodic... material and assign a score. The following table lists the possible scores, the criteria used to assign...

7 CFR 764.459 - Evaluation of borrower progress.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Requirements § 764.459 Evaluation of borrower progress. (a) The vendor must provide the Agency with a periodic... material and assign a score. The following table lists the possible scores, the criteria used to assign...

7 CFR 764.459 - Evaluation of borrower progress.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Requirements § 764.459 Evaluation of borrower progress. (a) The vendor must provide the Agency with a periodic... material and assign a score. The following table lists the possible scores, the criteria used to assign...

Decontamination of combustion gases in fluidized bed incinerators

DOEpatents

Leon, Albert M.

1982-01-01

Sulfur-containing atmospheric pollutants are effectively removed from exit gas streams produced in a fluidized bed combustion system by providing a fluidized bed of particulate material, i.e. limestone and/or dolomite wherein a concentration gradient is maintained in the vertical direction. Countercurrent contacting between upwardly directed sulfur containing combustion gases and descending sorbent particulate material creates a concentration gradient across the vertical extent of the bed characterized in progressively decreasing concentration of sulfur, sulfur dioxide and like contaminants upwardly and decreasing concentration of e.g. calcium oxide, downwardly. In this manner, gases having progressively decreasing sulfur contents contact correspondingly atmospheres having progressively increasing concentrations of calcium oxide thus assuring optimum sulfur removal.

Progress in the Field of Constructing Near-Infrared Light-Responsive Drug Delivery Platforms.

PubMed

Zhou, Fang; Wang, Hanjie; Chang, Jin

2016-03-01

Stimuli-responsive materials have taken replace of traditional drug carriers due to their ability to achieve controlled release of their encapsulated contents. A variety of sensitive materials, such as polymers that respond to pH, light, and magnetic fields, are widely used to construct drug carriers, and achieved good results. Specifically, near-infrared light (NIR) responsive materials are of particular interest in drug delivery, as NIR can penetrate body tissue and is minimally absorbed by the body's water and hemoglobin and is less harmful to healthy cells than UV or visible light. Thus, the near-infrared excitation drug delivery systems (NIRDDSs) have some essential advantages just like being efficient to kill tumor cells, accurate to achieve the tumor sites and less damage to human body. Also, in the process of building the carriers, we may achieve a combination of controlled release chemotherapy, photothermal therapy (PTT) or photodynamic therapy (PDT). In addition, besides utilizing as drug delivery platforms, some carriers can achieve multifunctional tumor diagnosis and treatment, such as magnetic resonance imaging, optical imaging, drug carriers and PTT. In this review, based on the mechanism of NIR, we highlight diverse near-infrared light-responsive drug delivery platforms and recent advances in the development of NIRDDSs for cancer therapy primarily.

Spacelab

NASA Image and Video Library

1992-01-29

This photograph shows activities during the International Microgravity Laboratory-1 (IML-1) mission (STS-42) in the Payload Operations Control Center (POCC) at the Marshall Space Flight Center. The IML-1 mission was the first in a series of Shuttle flights dedicated to fundamental materials and life sciences research. The mission was to explore, in depth, the complex effects of weightlessness on living organisms and materials processing. The crew conducted experiments on the human nervous system's adaptation to low gravity and the effects on other life forms such as shrimp eggs, lentil seedlings, fruit fly eggs, and bacteria. Low gravity materials processing experiments included crystal growth from a variety of substances such as enzymes, mercury, iodine, and virus. The International space science research organizations that participated in this mission were: The U.S. National Aeronautics and Space Administration, the European Space Agency, the Canadian Space Agency, the French National Center for Space Studies, the German Space Agency, and the National Space Development Agency of Japan. The POCC was the air/ground communication charnel used between the astronauts aboard the Spacelab and scientists, researchers, and ground control teams during the Spacelab missions. The facility made instantaneous video and audio communications possible for scientists on the ground to follow the progress and to send direct commands of their research almost as if they were in space with the crew.

Frontiers of controlling energy levels at interfaces

NASA Astrophysics Data System (ADS)

Koch, Norbert

The alignment of electron energy levels at interfaces between semiconductors, dielectrics, and electrodes determines the function and efficiency of all electronic and optoelectronic devices. Reliable guidelines for predicting the level alignment for a given material combination and methods to adjust the intrinsic energy landscape are needed to enable efficient engineering approaches. These are sufficiently understood for established electronic materials, e.g., Si, but for the increasing number of emerging materials, e.g., organic and 2D semiconductors, perovskites, this is work in progress. The intrinsic level alignment and the underlying mechanisms at interfaces between organic and inorganic semiconductors are discussed first. Next, methods to alter the level alignment are introduced, which all base on proper charge density rearrangement at a heterojunction. As interface modification agents we use molecular electron acceptors and donors, as well as molecular photochromic switches that add a dynamic aspect and allow device multifunctionality. For 2D semiconductors surface transfer doping with molecular acceptors/donors transpires as viable method to locally tune the Fermi-level position in the energy gap. The fundamental electronic properties of a prototypical 1D interface between intrinsic and p-doped 2D semiconductor regions are derived from local (scanning probe) and area-averaged (photoemission) spectroscopy experiments. Future research opportunities for attaining unsurpassed interface control through charge density management are discussed.

Real-time Mesoscale Visualization of Dynamic Damage and Reaction in Energetic Materials under Impact

NASA Astrophysics Data System (ADS)

Chen, Wayne; Harr, Michael; Kerschen, Nicholas; Maris, Jesus; Guo, Zherui; Parab, Niranjan; Sun, Tao; Fezzaa, Kamel; Son, Steven

Energetic materials may be subjected to impact and vibration loading. Under these dynamic loadings, local stress or strain concentrations may lead to the formation of hot spots and unintended reaction. To visualize the dynamic damage and reaction processes in polymer bonded energetic crystals under dynamic compressive loading, a high speed X-ray phase contrast imaging setup was synchronized with a Kolsky bar and a light gas gun. Controlled compressive loading was applied on PBX specimens with a single or multiple energetic crystal particles and impact-induced damage and reaction processes were captured using the high speed X-ray imaging setup. Impact velocities were systematically varied to explore the critical conditions for reaction. At lower loading rates, ultrasonic exercitations were also applied to progressively damage the crystals, eventually leading to reaction. AFOSR, ONR.

Bright Photon Upconversion on Composite Organic Lanthanide Molecules through Localized Thermal Radiation.

PubMed

Ye, Huanqing; Bogdanov, Viktor; Liu, Sheng; Vajandar, Saumitra; Osipowicz, Thomas; Hernández, Ignacio; Xiong, Qihua

2017-12-07

Converting low-energy photons via thermal radiation can be a potential approach for utilizing infrared (IR) photons to improve photovoltaic efficiency. Lanthanide-containing materials have achieved great progress in IR-to-visible photon upconversion (UC). Herein, we first report bright photon, tunable wavelength UC through localized thermal radiation at the molecular scale with low excitation power density (<10 W/cm 2 ) realized on lanthanide complexes of perfluorinated organic ligands. This is enabled by engineering the pathways of nonradiative de-excitation and energy transfer in a composite of ytterbium and terbium perfluoroimidodiphosphinates. The IR-excited thermal UC and wavelength control is realized through the terbium activators sensitized by the ytterbium sensitizers having high luminescence efficiency. The metallic molecular composite thus can be a potential energy material in the use of the IR solar spectrum for thermal photovoltaic applications.

Non-thermal plasma technology for the development of antimicrobial surfaces: a review

NASA Astrophysics Data System (ADS)

Nikiforov, Anton; Deng, Xiaolong; Xiong, Qing; Cvelbar, U.; DeGeyter, N.; Morent, R.; Leys, Christophe

2016-05-01

Antimicrobial coatings are in high demand in many fields including the biomaterials and healthcare sectors. Within recent progress in nanoscience and engineering at the nanoscale, preparation of nanocomposite films containing metal nanoparticles (such as silver nanoparticles, copper nanoparticles, zinc oxide nanoparticles) is becoming an important step in manufacturing biomaterials with high antimicrobial activity. Controlled release of antibiotic agents and eliminating free nanoparticles are of equal importance for engineering antimicrobial nanocomposite materials. Compared to traditional chemical ‘wet’ methods, plasma deposition and plasma polymerization are promising approaches for the fabrication of nanocomposite films with the advantages of gas phase dry processes, effective use of chemicals and applicability to various substrates. In this article, we present a short overview of state-of-the-art engineering of antimicrobial materials based on the use of non-thermal plasmas at low and atmospheric pressure.

Engineering of oriented carbon nanotubes in composite materials

PubMed Central

Beigmoradi, Razieh; Mohebbi-Kalhori, Davod

2018-01-01

The orientation and arrangement engineering of carbon nanotubes (CNTs) in composite structures is considered a challenging issue. In this regard, two groups of in situ and ex situ techniques have been developed. In the first, the arrangement is achieved during CNT growth, while in the latter, the CNTs are initially grown in random orientation and the arrangement is then achieved during the device integration process. As the ex situ techniques are free from growth restrictions and more flexible in terms of controlling the alignment and sorting of the CNTs, they are considered by some as the preferred technique for engineering of oriented CNTs. This review focuses on recent progress in the improvement of the orientation and alignment of CNTs in composite materials. Moreover, the advantages and disadvantages of the processes are discussed as well as their future outlook. PMID:29515955

Myopia Control: A Review.

PubMed

Walline, Jeffrey J

2016-01-01

Slowing the progression of myopia has become a considerable concern for parents of myopic children. At the same time, clinical science is rapidly advancing the knowledge about methods to slow myopia progression. This article reviews the peer-reviewed literature regarding several modalities attempting to control myopia progression. Several strategies have been shown to be ineffective for myopia control, including undercorrection of myopic refractive error, alignment fit gas-permeable contact lenses, outdoor time, and bifocal of multifocal spectacles. However, a recent randomized clinical trial fitted progressing myopic children with executive bifocals for 3 years and found a 39% slowing of myopia progression for bifocal-only spectacles and 50% treatment effect for bifocal spectacles with base-in prism, although there was not a significant difference in progression between the bifocal-only and bifocal plus prism groups. Interestingly, outdoor time has shown to be effective for reducing the onset of myopia but not for slowing the progression of myopic refractive error. More effective methods of myopia control include orthokeratology, soft bifocal contact lenses, and antimuscarinic agents. Orthokeratology and soft bifocal contact lenses are both thought to provide myopic blur to the retina, which acts as a putative cue to slow myopic eye growth. Each of these myopia control methods provides, on average, slightly less than 50% slowing of myopia progression. All studies have shown clinically meaningful slowing of myopia progression, including several randomized clinical trials. The most investigated antimuscarinic agents include pirenzepine and atropine. Pirenzepine slows myopia progression by approximately 40%, but it is not commercially available in the United States. Atropine provides the best myopia control, but the cycloplegic and mydriatic side effects render it a rarely prescribed myopia control agent in the United States. However, low-concentration atropine has been shown to provide effective myopia control with far fewer side effects than 1.0% atropine. Finally, two agents, low-concentration atropine and outdoor time have been shown to reduce the likelihood of myopia onset. Over the past few years, much has been learned about how to slow the progression of nearsightedness in children, but we still have a lot to learn.

Superatom Thermoelectric Materials

DTIC Science & Technology

2012-07-30

Superatom Thermoelectric Materials 2cd Multifunctional Materials for Defense Workshop 30 July 2012 Materials & Manufacturing Directorate AFRL...number. 1. REPORT DATE 30 JUL 2012 2. REPORT TYPE 3. DATES COVERED 00-00-2012 to 00-00-2012 4. TITLE AND SUBTITLE Superatom Thermoelectric ...Advantages of Superatoms • Fullerenes/Fullerides • Progress • Conlcusions Thermoelectric Architecture • Two materials in contact – N and P

Printing, folding and assembly methods for forming 3D mesostructures in advanced materials

NASA Astrophysics Data System (ADS)

Zhang, Yihui; Zhang, Fan; Yan, Zheng; Ma, Qiang; Li, Xiuling; Huang, Yonggang; Rogers, John A.

2017-03-01

A rapidly expanding area of research in materials science involves the development of routes to complex 3D structures with feature sizes in the mesoscopic range (that is, between tens of nanometres and hundreds of micrometres). A goal is to establish methods for controlling the properties of materials systems and the function of devices constructed with them, not only through chemistry and morphology, but also through 3D architectures. The resulting systems, sometimes referred to as metamaterials, offer engineered behaviours with optical, thermal, acoustic, mechanical and electronic properties that do not occur in the natural world. Impressive advances in 3D printing techniques represent some of the most broadly recognized developments in this field, but recent successes with strategies based on concepts in origami, kirigami and deterministic assembly provide additional, unique options in 3D design and high-performance materials. In this Review, we highlight the latest progress and trends in methods for fabricating 3D mesostructures, beginning with the development of advanced material inks for nozzle-based approaches to 3D printing and new schemes for 3D optical patterning. In subsequent sections, we summarize more recent methods based on folding, rolling and mechanical assembly, including their application with materials such as designer hydrogels, monocrystalline inorganic semiconductors and graphene.

Shaping Nanoparticles with Hydrophilic Compositions and Hydrophobic Properties as Nanocarriers for Antibiotic Delivery

PubMed Central

2015-01-01

Inspired by the lotus effect in nature, surface roughness engineering has led to novel materials and applications in many fields. Despite the rapid progress in superhydrophobic and superoleophobic materials, this concept of Mother Nature’s choice is yet to be applied in the design of advanced nanocarriers for drug delivery. Pioneering work has emerged in the development of nanoparticles with rough surfaces for gene delivery; however, the preparation of nanoparticles with hydrophilic compositions but with enhanced hydrophobic property at the nanoscale level employing surface topology engineering remains a challenge. Herein we report for the first time the unique properties of mesoporous hollow silica (MHS) nanospheres with controlled surface roughness. Compared to MHS with a smooth surface, rough mesoporous hollow silica (RMHS) nanoparticles with the same hydrophilic composition show unusual hydrophobicity, leading to higher adsorption of a range of hydrophobic molecules and controlled release of hydrophilic molecules. RMHS loaded with vancomycin exhibits an enhanced antibacterial effect. Our strategy provides a new pathway in the design of novel nanocarriers for diverse bioapplications. PMID:27162988

Progress Report on Long Hold Time Creep Fatigue of Alloy 617 at 850°C

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

Carroll, Laura Jill

Alloy 617 is the leading candidate material for an intermediate heat exchanger for the very high temperature reactor. To evaluate the behavior of this material in the expected service conditions, strain-controlled cyclic tests that include long hold times up to 240 minutes at maximum tensile strain were conducted at 850°C. In terms of the total number of cycles to failure, the fatigue resistance decreased when a hold time was added at peak tensile strain. Increases in the tensile hold duration degraded the creep-fatigue resistance, at least to the investigated strain controlled hold time of up to 60 minutes at themore » 0.3% strain range and 240 minutes at the 1.0% strain range. The creep-fatigue deformation mode is considered relative to the lack of saturation, or continually decreasing number of cycles to failure with increasing hold times. Additionally, preliminary values from the 850°C creep-fatigue data are calculated for the creep-fatigue damage diagram and have higher values of creep damage than those from tests at 950°C.« less

Nanobiotechnology: synthetic biology meets materials science.

PubMed

Jewett, Michael C; Patolsky, Fernando

2013-08-01

Nanotechnology, the area of science focused on the control of matter in the nanometer scale, allows ground-breaking changes of the fundamental properties of matter that are often radically different compared to those exhibited by the bulk counterparts. In view of the fact that dimensionality plays a key role in determining the qualities of matter, the realization of the great potential of nanotechnology has opened the door to other disciplines such as life sciences and medicine, where the merging between them offers exciting new applications, along with basic science research. The application of nanotechnology in life sciences, nanobiotechnology, is now having a profound impact on biological circuit design, bioproduction systems, synthetic biology, medical diagnostics, disease therapy and drug delivery. This special issue is dedicated to the overview of how we are learning to control biopolymers and biological machines at the molecular- and nanoscale. In addition, it covers far-reaching progress in the design and synthesis of nanoscale materials, thus enabling the construction of integrated systems in which the component blocks are comparable in size to the chemical and biological entities under investigation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Progress in speckle-shift strain measurement

NASA Technical Reports Server (NTRS)

Lant, Christian T.; Barranger, John P.; Oberle, Lawrence G.; Greer, Lawrence C., III

1991-01-01

The Instrumentation and Control Technology Division of the Lewis Research Center has been developing an in-house capability to make one dimensional and two dimensional optical strain measurements on high temperature test specimens. The measurements are based on a two-beam speckle-shift technique. The development of composite materials for use in high temperature applications is generating interest in using the speckle-shift technique to measure strains on small diameter fibers and wires of various compositions. The results of preliminary speckle correlation tests on wire and fiber specimens are covered, and the advanced system currently under development is described.

Ultralightweight Ballute Technology Advances

NASA Technical Reports Server (NTRS)

Masciarelli, Jim; Miller, Kevin

2005-01-01

Ultralightweight ballutes offer the potential to provide the deceleration for entry and aerocapture missions at a fraction of the mass of traditional methods. A team consisting of Ball Aerospace, ILC Dover, NASA Langley, NASA Johnson, and the Jet Propulsion Laboratory has been addressing the technical issues associated with ultralightweight ballutes for aerocapture at Titan. Significant progress has been made in the areas of ballute materials, aerothermal analysis, trajectory control, and aeroelastic modeling. The status and results of efforts in these areas are presented. The results indicate that an ultralightweight ballute system mass of 8 to 10 percent of the total entry mass is possible.

Net shape fabrication of Alpha Silicon Carbide turbine components

NASA Technical Reports Server (NTRS)

Storm, R. S.

1982-01-01

Development of Alpha Silicon Carbide components by net shape fabrication techniques has continued in conjunction with several turbine engine programs. Progress in injection molding of simple parts has been extended to much larger components. Turbine rotors fabricated by a one piece molding have been successfully spin tested above design speeds. Static components weighing up to 4.5 kg and 33 cc in diameter have also been produced using this technique. Use of sintering fixtures significantly improves dimensional control. A new Si-SiC composite material has also been developed with average strengths up to 1000 MPa (150 ksi) at 1200 C.

Background research in support of the new grant proposal: Research consortium for X-ray topography on line X-19 at NSLS

NASA Astrophysics Data System (ADS)

Bilello, J. C.

1983-11-01

The status of the construction and installation of components of the synchrotron topography station is reported as well as progress in the development of hardware for interfacing and software for interactively controlling the 13 motors which automate the facility. Research focuses on the problem of X-ray optics and on techniques for applying topography to materials science. There is colaboration with other researchers in studying the nature of brittle fracture of refractory metals and in interpreting contact in the vicinity of crack tips.

Cryogenic balances for the US NTF

NASA Technical Reports Server (NTRS)

Ferris, Alice T.

1989-01-01

Force balances were used to obtain aerodynamic data in the National Transonic Facility (NTF) wind tunnel since it became operational in 1983. These balances were designed, fabricated, gaged, and calibrated to Langley Research Center's specifications to operate over the temperature range of -320 F to +140 F without thermal control. Some of the materials and procedures developed to obtain a balance that would perform in this environment are reviewed. The degree of success in using these balances thus far is reported. Some of the problem areas that need additional work are specified and some of the progress addressing these problems is described.

Synthesis, properties and biomedical applications of carbon-based quantum dots: An updated review.

PubMed

Namdari, Pooria; Negahdari, Babak; Eatemadi, Ali

2017-03-01

Carbon-based quantum dots (CQDs) are a newly developed class of carbon nano-materials that have attracted much interest and attention as promising competitors to already available semiconductor quantum dots owing to their un-comparable and unique properties. In addition, controllability of CQDs unique physiochemical properties is as a result of their surface passivation and functionalization. This is an update article (between 2013 and 2016) on the recent progress, characteristics and synthesis methods of CQDs and different advantages in varieties of applications. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Nanocomposite Hydrogels: 3D Polymer-Nanoparticle Synergies for On-Demand Drug Delivery.

PubMed

Merino, Sonia; Martín, Cristina; Kostarelos, Kostas; Prato, Maurizio; Vázquez, Ester

2015-05-26

Considerable progress in the synthesis and technology of hydrogels makes these materials attractive structures for designing controlled-release drug delivery systems. In particular, this review highlights the latest advances in nanocomposite hydrogels as drug delivery vehicles. The inclusion/incorporation of nanoparticles in three-dimensional polymeric structures is an innovative means for obtaining multicomponent systems with diverse functionality within a hybrid hydrogel network. Nanoparticle-hydrogel combinations add synergistic benefits to the new 3D structures. Nanogels as carriers for cancer therapy and injectable gels with improved self-healing properties have also been described as new nanocomposite systems.

Effective properties of dispersed phase reinforced composite materials with perfect and imperfect interfaces

NASA Astrophysics Data System (ADS)

Han, Ru

This thesis focuses on the analysis of dispersed phase reinforced composite materials with perfect as well as imperfect interfaces using the Boundary Element Method (BEM). Two problems of interest are considered, namely, to determine the limitations in the use of effective properties and the analysis of failure progression at the inclusion-matrix interface. The effective moduli (effective Young's modulus, effective Poisson's ratio, effective shear modulus, and effective bulk modulus) of composite materials can be determined at the mesoscopic level using three-dimensional parallel BEM simulations. By comparing the mesoscopic BEM results and the macroscopic results based on effective properties, limitations in the effective property approach can be determined. Decohesion is an important failure mode associated with fiber-reinforced composite materials. Analysis of failure progression at the fiber-matrix interface in fiber-reinforced composite materials is considered using a softening decohesion model consistent with thermodynamic concepts. In this model, the initiation of failure is given directly by a failure criterion. Damage is interpreted by the development of a discontinuity of displacement. The formulation describing the potential development of damage is governed by a discrete decohesive constitutive equation. Numerical simulations are performed using the direct boundary element method. Incremental decohesion simulations illustrate the progressive evolution of debonding zones and the propagation of cracks along the interfaces. The effect of decohesion on the macroscopic response of composite materials is also investigated.

Lockheed laminar-flow control systems development and applications

NASA Technical Reports Server (NTRS)

Lange, Roy H.

1987-01-01

Progress is summarized from 1974 to the present in the practical application of laminar-flow control (LFC) to subsonic transport aircraft. Those efforts included preliminary design system studies of commercial and military transports and experimental investigations leading to the development of the leading-edge flight test article installed on the NASA JetStar flight test aircraft. The benefits of LFC on drag, fuel efficiency, lift-to-drag ratio, and operating costs are compared with those for turbulent flow aircraft. The current activities in the NASA Industry Laminar-Flow Enabling Technologies Development contract include summaries of activities in the Task 1 development of a slotted-surface structural concept using advanced aluminum materials and the Task 2 preliminary conceptual design study of global-range military hybrid laminar flow control (HLFC) to obtain data at high Reynolds numbers and at Mach numbers representative of long-range subsonic transport aircraft operation.

Inductively guided circuits for ultracold dressed atoms

PubMed Central

Sinuco-León, German A.; Burrows, Kathryn A.; Arnold, Aidan S.; Garraway, Barry M.

2014-01-01

Recent progress in optics, atomic physics and material science has paved the way to study quantum effects in ultracold atomic alkali gases confined to non-trivial geometries. Multiply connected traps for cold atoms can be prepared by combining inhomogeneous distributions of DC and radio-frequency electromagnetic fields with optical fields that require complex systems for frequency control and stabilization. Here we propose a flexible and robust scheme that creates closed quasi-one-dimensional guides for ultracold atoms through the ‘dressing’ of hyperfine sublevels of the atomic ground state, where the dressing field is spatially modulated by inductive effects over a micro-engineered conducting loop. Remarkably, for commonly used atomic species (for example, 7Li and 87Rb), the guide operation relies entirely on controlling static and low-frequency fields in the regimes of radio-frequency and microwave frequencies. This novel trapping scheme can be implemented with current technology for micro-fabrication and electronic control. PMID:25348163

Two-dimensional transition metal dichalcogenides as atomically thin semiconductors: opportunities and challenges.

PubMed

Duan, Xidong; Wang, Chen; Pan, Anlian; Yu, Ruqin; Duan, Xiangfeng

2015-12-21

The discovery of graphene has ignited intensive interest in two-dimensional layered materials (2DLMs). These 2DLMs represent a new class of nearly ideal 2D material systems for exploring fundamental chemistry and physics at the limit of single-atom thickness, and have the potential to open up totally new technological opportunities beyond the reach of existing materials. In general, there are a wide range of 2DLMs in which the atomic layers are weakly bonded together by van der Waals interactions and can be isolated into single or few-layer nanosheets. The van der Waals interactions between neighboring atomic layers could allow much more flexible integration of distinct materials to nearly arbitrarily combine and control different properties at the atomic scale. The transition metal dichalcogenides (TMDs) (e.g., MoS2, WSe2) represent a large family of layered materials, many of which exhibit tunable band gaps that can undergo a transition from an indirect band gap in bulk crystals to a direct band gap in monolayer nanosheets. These 2D-TMDs have thus emerged as an exciting class of atomically thin semiconductors for a new generation of electronic and optoelectronic devices. Recent studies have shown exciting potential of these atomically thin semiconductors, including the demonstration of atomically thin transistors, a new design of vertical transistors, as well as new types of optoelectronic devices such as tunable photovoltaic devices and light emitting devices. In parallel, there have also been considerable efforts in developing diverse synthetic approaches for the rational growth of various forms of 2D materials with precisely controlled chemical composition, physical dimension, and heterostructure interface. Here we review the recent efforts, progress, opportunities and challenges in exploring the layered TMDs as a new class of atomically thin semiconductors.

Silicon Carbide Solar Cells Investigated

NASA Technical Reports Server (NTRS)

Bailey, Sheila G.; Raffaelle, Ryne P.

2001-01-01

The semiconductor silicon carbide (SiC) has long been known for its outstanding resistance to harsh environments (e.g., thermal stability, radiation resistance, and dielectric strength). However, the ability to produce device-quality material is severely limited by the inherent crystalline defects associated with this material and their associated electronic effects. Much progress has been made recently in the understanding and control of these defects and in the improved processing of this material. Because of this work, it may be possible to produce SiC-based solar cells for environments with high temperatures, light intensities, and radiation, such as those experienced by solar probes. Electronics and sensors based on SiC can operate in hostile environments where conventional silicon-based electronics (limited to 350 C) cannot function. Development of this material will enable large performance enhancements and size reductions for a wide variety of systems--such as high-frequency devices, high-power devices, microwave switching devices, and high-temperature electronics. These applications would supply more energy-efficient public electric power distribution and electric vehicles, more powerful microwave electronics for radar and communications, and better sensors and controls for cleaner-burning, more fuel-efficient jet aircraft and automobile engines. The 6H-SiC polytype is a promising wide-bandgap (Eg = 3.0 eV) semiconductor for photovoltaic applications in harsh solar environments that involve high-temperature and high-radiation conditions. The advantages of this material for this application lie in its extremely large breakdown field strength, high thermal conductivity, good electron saturation drift velocity, and stable electrical performance at temperatures as high as 600 C. This behavior makes it an attractive photovoltaic solar cell material for devices that can operate within three solar radii of the Sun.

Participating in Authentic Science with the Aid of Learning Progressions through Mission Earth Workshops

NASA Astrophysics Data System (ADS)

Lewis, P. M., Jr.; Taylor, J.; Harte, T.; Czajkowski, K. P.

2016-12-01

"MISSION EARTH: Fusing GLOBE with NASA Assets to Build Systemic Innovation In STEM Education" is one of the new education cooperative agreements funded by the NASA Science Mission Directorate. Students will learn how to conduct "real science" through hands-on data collection using Global Learning and Observations to Benefit the Environment (GLOBE) protocols combined with other NASA science educational materials. This project aims to work with educators spanning the full K-12 range, requiring three grade bands of learning progressions and vertical alignment among materials and resources to best meet classroom needs. From K to 12 students have vastly different abilities to conduct and learn from scientific investigations. Hand-picked NASA assets will provide appropriate exposure across the curriculum and grade bands, and we are developing unique learning progressions that bring together GLOBE protocols for data collection and learning activities, NASA data sets through MY NASA DATA for data comparison, and more. The individual materials are not limited to science, but also include all elements of STEM with literacy components added in where appropriate. This will give the students an opportunity to work on better understanding the world around them in a well-rounded way, and offer cross-subject/classroom exposure to improve student understanding. To ensure that these learning progressions can continue to be used in the classroom in the future, alignment to the Next Generation Science Standards will help frame all of the materials and products. The learning progressions will be living documents that will change based on context. After several iterations, it is our goal to produce learning progressions for grades K-12 that will allow any STEM teacher to pick up and infuse NASA and GLOBE in their classroom at any location and at any time in their school year. This presentation will share results from the first year of development for this project.

Geologic controls on the formation of lakes in north-central Florida

USGS Publications Warehouse

Kindinger, Jack G.; Davis, Jeffrey B.; Flocks, James G.; Pitman, Janet K.; Carroll, Alan R.

1998-01-01

Fluid exchange between surficial waters and groundwater, as well as the processes that control this exchange, are of critical concern to water management districts and planners. Digital high-resolution seismic systems were used to collect geophysical data from 30 lakes of north-central Florida. Although using seismic profile data in the past has been less than successful, the use of digital technology has increased the potential for success. Seismic profiles collected from the lakes of north-central Florida have shown the potential application of these techniques in understanding the formation of individual lakes. In each case study, lake structure and geomorphology were controlled by solution and/or mechanical processes. Processes that control lake development are twofold: 1) karstification or dissolution of the underlying limestone, and 2) me collapse, subsidence, or slumping of overburden to form sinkholes. Initial lake formation is directly related to the karst topography of the underlying host limestone. Lake size and shape are a factor of the thickness of overburden and size of the collapse or subsidence and/or clustering of depressions allowing for lake development. Lake development is through progressive sequence stages to maturity that can be delineated into geomorphic types. Case studies have shown that lakes can be divided by geomorphic types into progressive developmental phases: (1) active subsidence or collapse phase (young) - the open to partially filled collapse structures typically associated with sink holes; (2) transitional phase (middle age) - the sinkhole is plugged as the voids within the collapse are filled with sediment, periodic reactivation may occur; (3) baselevel phase (mature) - active sinkholes are progressively plugged by the continual erosion of material into the basin, and eventually sediment fills the basins; and (4) polje (drowned prairie) - broad flat-bottom basins located within the epiphreatic zone that are inundated at high stages of the water table and have one or all phases of sinkhole development and many types of karst and karren features. Most lakes in this study have a small diameter (

Welding Supplementary Units.

ERIC Educational Resources Information Center

Johnson, Don; And Others

This document contains supplemental materials for special needs high school students intended to facilitate their mainstreaming in regular welding classes. Teacher's materials precede the materials for students and include general notes for the instructor, suggestions, eight references, a class progress chart, a questionnaire on the usefulness of…

Auto Mechanics Supplementary Units.

ERIC Educational Resources Information Center

Donovan, Roger; Smith, Sam

This document contains supplemental materials for special needs high school students intended to facilitate their mainstreaming in regular auto mechanics courses. Teacher's materials precede the materials for students and include general notes for the instructor, suggestions, 18 references, a class progress chart, a questionnaire on the usefulness…

Barriers to applying advanced high-temperature materials

NASA Astrophysics Data System (ADS)

Premkumar, M. K.

1993-01-01

During the past 25 years, aerospace engineers and material scientists have made significant technical progress toward developing next-generation aircraft. However, while advanced high-temperature materials continue to be developed, the outlook for their future application is uncertain and will depend on the ability of these materials to satisfy a more diverse market.

Solid State Division progress report for period ending March 31, 1997

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

Green, P.H.; Hinton, L.W.

1997-12-01

This report covers research progress in the Solid State Division from April 1, 1995, through March 31, 1997. During this period, the division conducted a broad, interdisciplinary materials research program in support of Department of Energy science and technology missions. The report includes brief summaries of research activities in condensed matter theory, neutron scattering, synthesis and characterization of materials, ion beam and laser processing, and the structure of solids and surfaces. An addendum includes listings of division publications and professional activities.

Progress in manufacturing large primary aircraft structures using the stitching/RTM process

NASA Technical Reports Server (NTRS)

Markus, Alan; Thrash, Patrick; Rohwer, Kim

1993-01-01

The Douglas Aircraft/NASA Act contract has been focused over the past three years at developing a materials, manufacturing, and cost base for stitched/Resin Transfer Molded (RTM) composites. The goal of the program is to develop RTM and stitching technology to provide enabling technology for application of these materials in primary aircraft structure with a high degree of confidence. Presented in this paper will be the progress to date in the area of manufacturing and associated cost values of stitched/RTM composites.

Advances in Fabrication Materials of Honeycomb Structure Films by the Breath-Figure Method

PubMed Central

Heng, Liping; Wang, Bin; Li, Muchen; Zhang, Yuqi; Jiang, Lei

2013-01-01

Creatures in nature possess almost perfect structures and properties, and exhibit harmonization and unification between structure and function. Biomimetics, mimicking nature for engineering solutions, provides a model for the development of functional surfaces with special properties. Recently, honeycomb structure materials have attracted wide attention for both fundamental research and practical applications and have become an increasingly hot research topic. Though progress in the field of breath-figure formation has been reviewed, the advance in the fabrication materials of bio-inspired honeycomb structure films has not been discussed. Here we review the recent progress of honeycomb structure fabrication materials which were prepared by the breath-figure method. The application of breath figures for the generation of all kinds of honeycomb is discussed. PMID:28809319

Archean komatiite volcanism controlled by the evolution of early continents.

PubMed

Mole, David R; Fiorentini, Marco L; Thebaud, Nicolas; Cassidy, Kevin F; McCuaig, T Campbell; Kirkland, Christopher L; Romano, Sandra S; Doublier, Michael P; Belousova, Elena A; Barnes, Stephen J; Miller, John

2014-07-15

The generation and evolution of Earth's continental crust has played a fundamental role in the development of the planet. Its formation modified the composition of the mantle, contributed to the establishment of the atmosphere, and led to the creation of ecological niches important for early life. Here we show that in the Archean, the formation and stabilization of continents also controlled the location, geochemistry, and volcanology of the hottest preserved lavas on Earth: komatiites. These magmas typically represent 50-30% partial melting of the mantle and subsequently record important information on the thermal and chemical evolution of the Archean-Proterozoic Earth. As a result, it is vital to constrain and understand the processes that govern their localization and emplacement. Here, we combined Lu-Hf isotopes and U-Pb geochronology to map the four-dimensional evolution of the Yilgarn Craton, Western Australia, and reveal the progressive development of an Archean microcontinent. Our results show that in the early Earth, relatively small crustal blocks, analogous to modern microplates, progressively amalgamated to form larger continental masses, and eventually the first cratons. This cratonization process drove the hottest and most voluminous komatiite eruptions to the edge of established continental blocks. The dynamic evolution of the early continents thus directly influenced the addition of deep mantle material to the Archean crust, oceans, and atmosphere, while also providing a fundamental control on the distribution of major magmatic ore deposits.

Archean komatiite volcanism controlled by the evolution of early continents

PubMed Central

Mole, David R.; Fiorentini, Marco L.; Thebaud, Nicolas; Cassidy, Kevin F.; McCuaig, T. Campbell; Kirkland, Christopher L.; Romano, Sandra S.; Doublier, Michael P.; Belousova, Elena A.; Barnes, Stephen J.; Miller, John

2014-01-01

The generation and evolution of Earth’s continental crust has played a fundamental role in the development of the planet. Its formation modified the composition of the mantle, contributed to the establishment of the atmosphere, and led to the creation of ecological niches important for early life. Here we show that in the Archean, the formation and stabilization of continents also controlled the location, geochemistry, and volcanology of the hottest preserved lavas on Earth: komatiites. These magmas typically represent 50–30% partial melting of the mantle and subsequently record important information on the thermal and chemical evolution of the Archean–Proterozoic Earth. As a result, it is vital to constrain and understand the processes that govern their localization and emplacement. Here, we combined Lu-Hf isotopes and U-Pb geochronology to map the four-dimensional evolution of the Yilgarn Craton, Western Australia, and reveal the progressive development of an Archean microcontinent. Our results show that in the early Earth, relatively small crustal blocks, analogous to modern microplates, progressively amalgamated to form larger continental masses, and eventually the first cratons. This cratonization process drove the hottest and most voluminous komatiite eruptions to the edge of established continental blocks. The dynamic evolution of the early continents thus directly influenced the addition of deep mantle material to the Archean crust, oceans, and atmosphere, while also providing a fundamental control on the distribution of major magmatic ore deposits. PMID:24958873

Mitigation of biofouling using coatings: Year 2. Quarterly progress report No. 1. Calspan report 6782-M-5

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

Meyer, A.E.; King, R.W.

1982-01-15

Objectives of this project are to evaluate benefits associated with control of the surface energetic properties of materials used in heat exchangers; and to identify preferred ranges of these surface conditions that minimize deposits of biological fouling known to deteriorate heat exchange efficiencies in seawater, brackish water, and freshwater systems. The technical approach employed uses special diagnostic plates in novel flow cells where fluid flow conditions can be well-controlled, modifying the surface chemistry and surface energy of the plates with very thin coatings and examining the earliest events of biofouling caused by macromolecules and microbial organisms. For the present phasemore » of the project (Year 2), attention will be focussed on biofouling in a freshwater/brackish water system.« less

Arterial hypertension and skin allergy are risk factors for progression from dengue to dengue hemorrhagic fever: a case control study.

PubMed

Teixeira, Maria Glória; Paixão, Enny S; Costa, Maria da Conceição N; Cunha, Rivaldo V; Pamplona, Luciano; Dias, Juarez P; Figueiredo, Camila A; Figueiredo, Maria Aparecida A; Blanton, Ronald; Morato, Vanessa; Barreto, Maurício L; Rodrigues, Laura C

2015-05-01

Currently, knowledge does not allow early prediction of which cases of dengue fever (DF) will progress to dengue hemorrhagic fever (DHF), to allow early intervention to prevent progression or to limit severity. The objective of this study is to investigate the hypothesis that some specific comorbidities increase the likelihood of a DF case progressing to DHF. A concurrent case-control study, conducted during dengue epidemics, from 2009 to 2012. Cases were patients with dengue fever that progressed to DHF, and controls were patients of dengue fever who did not progress to DHF. Logistic regression was used to estimate the association between DHF and comorbidities. There were 490 cases of DHF and 1,316 controls. Among adults, progression to DHF was associated with self-reported hypertension (OR = 1.6; 95% CI 1.1-2.1) and skin allergy (OR = 1.8; 95% CI 1.1-3.2) with DHF after adjusting for ethnicity and socio-economic variables. There was no statistically significant association between any chronic disease and progression to DHF in those younger than 15 years. Physicians attending patients with dengue fever should keep those with hypertension or skin allergies in health units to monitor progression for early intervention. This would reduce mortality by dengue.

Assessment and selection of materials for ITER in-vessel components

NASA Astrophysics Data System (ADS)

Kalinin, G.; Barabash, V.; Cardella, A.; Dietz, J.; Ioki, K.; Matera, R.; Santoro, R. T.; Tivey, R.; ITER Home Teams

2000-12-01

During the international thermonuclear experimental reactor (ITER) engineering design activities (EDA) significant progress has been made in the selection of materials for the in-vessel components of the reactor. This progress is a result of the worldwide collaboration of material scientists and industries which focused their effort on the optimisation of material and component manufacturing and on the investigation of the most critical material properties. Austenitic stainless steels 316L(N)-IG and 316L, nickel-based alloys Inconel 718 and Inconel 625, Ti-6Al-4V alloy and two copper alloys, CuCrZr-IG and CuAl25-IG, have been proposed as reference structural materials, and ferritic steel 430, and austenitic steel 304B7 with the addition of boron have been selected for some specific parts of the ITER in-vessel components. Beryllium, tungsten and carbon fibre composites are considered as plasma facing armour materials. The data base on the properties of all these materials is critically assessed and briefly reviewed in this paper together with the justification of the material selection (e.g., effect of neutron irradiation on the mechanical properties of materials, effect of manufacturing cycle, etc.).

Amarillo National Resource Center for Plutonium. Quarterly technical progress report, May 1, 1997--July 31, 1997

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

NONE

Progress summaries are provided from the Amarillo National Center for Plutonium. Programs include the plutonium information resource center, environment, public health, and safety, education and training, nuclear and other material studies.

Progress Update: Stack Project Complete

ScienceCinema

Cody, Tom

2017-12-12

Progress update from the Savannah River Site. The 75 foot 293 F Stack, built for plutonium production, was cut down to size in order to prevent injury or release of toxic material if the structure were to collapse due to harsh weather.

Functional mesoporous materials for energy applications: solar cells, fuel cells, and batteries

NASA Astrophysics Data System (ADS)

Ye, Youngjin; Jo, Changshin; Jeong, Inyoung; Lee, Jinwoo

2013-05-01

This feature article presents recent progress made in the synthesis of functional ordered mesoporous materials and their application as high performance electrodes in dye-sensitized solar cells (DSCs) and quantum dot-sensitized solar cells (QDSCs), fuel cells, and Li-ion batteries. Ordered mesoporous materials have been mainly synthesized using two representative synthetic methods: the soft template and hard template methods. To overcome the limitations of these two methods, a new method called CASH was suggested. The CASH method combines the advantages of the soft and hard template methods by employing a diblock copolymer, PI-b-PEO, which contains a hydrophilic block and an sp2-hybridized-carbon-containing hydrophobic block as a structure-directing agent. After discussing general techniques used in the synthesis of mesoporous materials, this article presents recent applications of mesoporous materials as electrodes in DSCs and QDSCs, fuel cells, and Li-ion batteries. The role of material properties and mesostructures in device performance is discussed in each case. The developed soft and hard template methods, along with the CASH method, allow control of the pore size, wall composition, and pore structure, providing insight into material design and optimization for better electrode performances in these types of energy conversion devices. This paper concludes with an outlook on future research directions to enable breakthroughs and overcome current limitations in this field.

Functional mesoporous materials for energy applications: solar cells, fuel cells, and batteries.

PubMed

Ye, Youngjin; Jo, Changshin; Jeong, Inyoung; Lee, Jinwoo

2013-06-07

This feature article presents recent progress made in the synthesis of functional ordered mesoporous materials and their application as high performance electrodes in dye-sensitized solar cells (DSCs) and quantum dot-sensitized solar cells (QDSCs), fuel cells, and Li-ion batteries. Ordered mesoporous materials have been mainly synthesized using two representative synthetic methods: the soft template and hard template methods. To overcome the limitations of these two methods, a new method called CASH was suggested. The CASH method combines the advantages of the soft and hard template methods by employing a diblock copolymer, PI-b-PEO, which contains a hydrophilic block and an sp(2)-hybridized-carbon-containing hydrophobic block as a structure-directing agent. After discussing general techniques used in the synthesis of mesoporous materials, this article presents recent applications of mesoporous materials as electrodes in DSCs and QDSCs, fuel cells, and Li-ion batteries. The role of material properties and mesostructures in device performance is discussed in each case. The developed soft and hard template methods, along with the CASH method, allow control of the pore size, wall composition, and pore structure, providing insight into material design and optimization for better electrode performances in these types of energy conversion devices. This paper concludes with an outlook on future research directions to enable breakthroughs and overcome current limitations in this field.

Textiles for protection against microorganism

NASA Astrophysics Data System (ADS)

Sauperl, O.

2016-04-01

Concerning micro-organisms such as bacteria, viruses and fungi, there is a huge progress in the development of textile materials and procedures which should effectively protect against these various pathogens. In this sense there is especially problematic hospital environment, where it is necessary to take into account properly designed textile material which, when good selected and composed, act as a good barrier against transfer of micro-organisms through material mainly in its wet state. Respect to this it is necessary to be familiar with the rules regarding selection of the input material, the choice of proper yarn construction, the choice of the proper weaving mode, the rules regarding selection of antimicrobial-active compound suitable for (eco-friendly) treatment, and the choice of the most appropriate test method by which it is possible objectively to conclude on the reduction of selected microorganism. As is well known, fabrics are three-dimensional structures with void and non-void areas. Therefore, the physical-chemical properties of the textile material/fabric, the surface characteristics together with the shape of microorganism, and the carriers' characteristics contribute to control the transfer of microorganism through textile material. Therefore, careful planning of textile materials and treatment procedure with the compound which is able to reduce micro-organism satisfactory is particularly important, especially due to the fact that in hospital environment population with impaired immune system is mainly presented.

A thirst for advancement

NASA Astrophysics Data System (ADS)

Hsiao, Benjamin S.; Chigome, Samuel; Torto, Nelson

2018-03-01

The resource-rich continent of Africa is showing signs of significant progress in materials science research and is harnessing a plethora of human and material resources to tackle a wide range of challenges.

CO2 laser irradiation enhances CaF2 formation and inhibits lesion progression on demineralized dental enamel-in vitro study.

PubMed

Zancopé, Bruna R; Rodrigues, Lívia P; Parisotto, Thais M; Steiner-Oliveira, Carolina; Rodrigues, Lidiany K A; Nobre-dos-Santos, Marinês

2016-04-01

This study evaluated if Carbon dioxide (CO2) (λ 10.6 μm) laser irradiation combined with acidulated phosphate fluoride gel application (APF gel) enhances "CaF2" uptake by demineralized enamel specimens (DES) and inhibits enamel lesion progression. Thus, two studies were conducted and DES were subjected to APF gel combined or not with CO2 laser irradiation (11.3 or 20.0 J/cm(2), 0.4 or 0.7 W) performed before, during, or after APF gel application. In study 1, 165 DES were allocated to 11 groups. Fluoride as "CaF2 like material" formed on enamel was determined in 100 DES (n = 10/group), and the surface morphologies of 50 specimens were evaluated by scanning electron microscopy (SEM) before and after "CaF2" extraction. In study 2, 165 DES (11 groups, n = 15), subjected to the same treatments as in study 1, were further subjected to a pH-cycling model to simulate a high cariogenic challenge. The progression of demineralization in DES was evaluated by cross-sectional microhardness and polarized light microscopy analyses. Laser at 11.3 J/cm(2) applied during APF gel application increased "CaF2" uptake on enamel surface. Laser irradiation and APF gel alone arrested the lesion progression compared with the control (p < 0.05). Areas of melting, fusion, and cracks were observed. CO2 laser irradiation, combined with a single APF application enhanced "CaF2" uptake on enamel surface and a synergistic effect was found. However, regarding the inhibition of caries lesion progression, no synergistic effect could be demonstrated. In conclusion, the results have shown that irradiation with specific laser parameters significantly enhanced CaF2 uptake by demineralized enamel and inhibited lesion progression.

How controllers compensate for the lack of flight progress strips.

DOT National Transportation Integrated Search

1996-02-01

The role of the Flight Progress Strip, currently used to display important flight data, has been debated because of long range plans to automate the air traffic control (ATC) human-computer interface. Currently, the Fight Progress Strip is viewed by ...

3D printing of soft-matter to open a new era of soft-matter MEMS/robotics (Conference Presentation)

NASA Astrophysics Data System (ADS)

Furukawa, Hidemitsu

2017-04-01

3D printing technology is becoming useful and applicable by the progress of information and communication technology (ICT). It means 3D printer is a kind of useful robot for additive manufacturing and is controlled by computer with human-friendly software. Once user starts to use 3D printing of soft-matter, one can immediately understand computer-aided design (CAD) and engineering (CAE) technology will be more important and applicable for soft-matter systems. User can easily design soft-matter objects and 3D-print them. User can easily apply 3D-printed soft-matter objects to develop new research and application on MEMS and robotics. Here we introduce the recent progress of 3D printing (i.e. additive manufacturing), especially focusing on our 3D gel printing. We are trying to develop new advanced research and applications of 3D gel printer, including GEL-MECHANICS, GEL-PHOTONICS, and GEL-ROBOTICS. In the gel-mechanics, we are developing new gel materials for mechanical engineering. Some gels have high-mechanical strength and shape memory properties. In the gel-photonics. We are applying our original characterizing system, named `Scanning Microscopic Light Scattering (SMILS)', to analyze 3D printed gel materials. In the gel-robotics, we focus on 3D printing of soft parts for soft-robotics made form gel materials, like gel finger. Also we are challenging to apply 3D gel printing to start new company, to innovate new businesses in county side, and to create new 3D-printed foods.

Recent progress on fabrication of memristor and transistor-based neuromorphic devices for high signal processing speed with low power consumption

NASA Astrophysics Data System (ADS)

Hadiyawarman; Budiman, Faisal; Goldianto Octensi Hernowo, Detiza; Pandey, Reetu Raj; Tanaka, Hirofumi

2018-03-01

The advanced progress of electronic-based devices for artificial neural networks and recent trends in neuromorphic engineering are discussed in this review. Recent studies indicate that the memristor and transistor are two types of devices that can be implemented as neuromorphic devices. The electrical switching characteristics and physical mechanism of neuromorphic devices based on metal oxide, metal sulfide, silicon, and carbon materials are broadly covered in this review. Moreover, the switching performance comparison of several materials mentioned above are well highlighted, which would be useful for the further development of memristive devices. Recent progress in synaptic devices and the application of a switching device in the learning process is also discussed in this paper.

Recent Progress in Iron-Based Electrode Materials for Grid-Scale Sodium-Ion Batteries.

PubMed

Fang, Yongjin; Chen, Zhongxue; Xiao, Lifen; Ai, Xinping; Cao, Yuliang; Yang, Hanxi

2018-03-01

Grid-scale energy storage batteries with electrode materials made from low-cost, earth-abundant elements are needed to meet the requirements of sustainable energy systems. Sodium-ion batteries (SIBs) with iron-based electrodes offer an attractive combination of low cost, plentiful structural diversity and high stability, making them ideal candidates for grid-scale energy storage systems. Although various iron-based cathode and anode materials have been synthesized and evaluated for sodium storage, further improvements are still required in terms of energy/power density and long cyclic stability for commercialization. In this Review, progress in iron-based electrode materials for SIBs, including oxides, polyanions, ferrocyanides, and sulfides, is briefly summarized. In addition, the reaction mechanisms, electrochemical performance enhancements, structure-composition-performance relationships, merits and drawbacks of iron-based electrode materials for SIBs are discussed. Such iron-based electrode materials will be competitive and attractive electrodes for next-generation energy storage devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recent progress in injectable bone repair materials research

NASA Astrophysics Data System (ADS)

Chen, Zonggang; Zhang, Xiuli; Kang, Lingzhi; Xu, Fei; Wang, Zhaoling; Cui, Fu-Zhai; Guo, Zhongwu

2015-12-01

Minimally invasive injectable self-setting materials are useful for bone repairs and for bone tissue regeneration in situ. Due to the potential advantages of these materials, such as causing minimal tissue injury, nearly no influence on blood supply, easy operation and negligible postoperative pain, they have shown great promises and successes in clinical applications. It has been proposed that an ideal injectable bone repair material should have features similar to that of natural bones, in terms of both the microstructure and the composition, so that it not only provides adequate stimulus to facilitate cell adhesion, proliferation and differentiation but also offers a satisfactory biological environment for new bone to grow at the implantation site. This article reviews the properties and applications of injectable bone repair materials, including those that are based on natural and synthetic polymers, calcium phosphate, calcium phosphate/polymer composites and calcium sulfate, to orthopedics and bone tissue repairs, as well as the progress made in biomimetic fabrication of injectable bone repair materials.

Use of a Lysine-Derived Urethane Surgical Adhesive as an Alternative to Progressive Tension Sutures in Abdominoplasty Patients: A Cohort Study.

PubMed

Spring, Michelle A

2018-04-07

Fluid accumulation is a common complication after abdominoplasty procedures, and is typically managed by the placement of post-surgical drains. Progressive tension sutures (PTS) have been shown to be an effective approach to reduce the dead space by point-wise mechanical fixation, allowing for drain-free procedures. Lysine-derived urethane surgical adhesive provides an alternative approach for mechanical fixation and reduction of dead space, and may reduce surgery time compared to PTS. This prospective, controlled, single center clinical study compared progressive tension suture wound closure technique without drains (control) to tissue adhesive wound closure technique without drains (test) during abdominoplasty surgery. The objective was to determine if lysine-derived urethane surgical adhesive is an effective alternative to PTS for drain-free abdominoplasty procedures. Patients undergoing abdominoplasty who met the established inclusion/exclusion criteria were consented and enrolled in the study. Ten PTS (control) cases were performed, followed immediately by ten tissue adhesive (test) cases. Drains were not used in any procedures. Key outcome measures included all major and minor post-surgical complications requiring any intervention, the time to place progressive tension sutures versus time for tissue adhesive application, and number of PTS attachments versus number of adhesive drops applied. Surgeries were completed over an 8-month period. No statistical differences were identified between the two groups with regard to age, BMI, dissection surface area or flap weight. No clinical seroma formation was observed in either group. In the control (PTS) group, two patients developed small areas of dermal closure suture abscess requiring removal of suture material. One control patient developed drainage and fat necrosis thought to be related to PTS above the incision and later required a scar revision. One tissue adhesive patient developed hypertrophic scars of both her breast reduction and abdominoplasty scars requiring additional treatment. The average time to place PTS in the control group was 10.7 minutes (range, 7-18 minutes) and the average number of sutures placed was 16.6 (range, 12-22 sutures). In the test group, the average time to place the tissue adhesive and hold pressure was 5.9 minutes (range 5.5-8.0 minutes). The average number of tissue adhesive drops applied was 69.6 (range: 63-78 drops). In the tissue adhesive group, both the reduction in time for flap adhesion and the increased number of adhesive points were statistically significant when compared to PTS. Lysine-derived urethane surgical adhesive was applied in less time than progressive tension sutures, even after accounting for holding pressure for 5 minutes. The tissue adhesive provided four times the number of attachment points compared to PTS, although the significance of this is not clear. There were no postoperative clinical seromas detected in either group and there were no major complications in either group. Based on these results, the use of lysine-derived urethane surgical adhesive was found to be a safe and effective alternative to progressive tension sutures to reduce seroma formation in drain-free abdominoplasty procedures.

The Role of Self-regulation and Affective Control in Predicting Interpersonal Reactivity of Drug Addicts

PubMed Central

Abolghasemi, Abbas; Rajabi, Saeed

2013-01-01

Background Due to its progressive nature in all aspects of life, addiction endangers the health of individuals, families and the society. Objectives The purpose of this study was to determine the role of self-regulation and affective control in predicting interpersonal reactivity of drug addicts. Materials and Methods This research is a correlation study. The statistical population of this study includes all drug addicts who were referred to addiction treatment centers of Ardabil in 2011 of whom 160 addicts were selected through convenience sampling. A self-regulation questionnaire, interpersonal reactivity questionnaire and affective control scale were used for data collection. Results Research results showed that self-regulation (r = -0.40) and affective control (r = -0.29) have a significant relationship with interpersonal reactivity of addicts (P < 0.001). The results of the multiple regression analysis indicated that 19 percent of interpersonal reactivity can be predicted by self-regulation and affective control. Conclusion These results suggest that self-regulation and affective control play an important role in exacerbating as well as reducing interpersonal reactivity of addicts. PMID:24971268

Small-Animal SPECT/CT of the Progression and Recovery of Rat Liver Fibrosis by Using an Integrin αvβ3-targeting Radiotracer.

PubMed

Yu, Xinhe; Wu, Yue; Liu, Hao; Gao, Liquan; Sun, Xianlei; Zhang, Chenran; Shi, Jiyun; Zhao, Huiyun; Jia, Bing; Liu, Zhaofei; Wang, Fan

2016-05-01

To assess the potential utility of an integrin αvβ3-targeting radiotracer, technetium 99m-PEG4-E[PEG4-cyclo(arginine-glycine-aspartic acid-D-phenylalanine-lysine)]2 ((99m)Tc-3PRGD2), for single photon emission computed tomography (SPECT)/computed tomography (CT) for monitoring of the progression and prognosis of liver fibrosis in a rat model. All animal experiments were performed by following the protocol approved by the institutional animal care and use committee. (99m)Tc-3PRGD2 was prepared and longitudinal SPECT/CT was performed to monitor the progression (n = 8) and recovery (n = 5) of liver fibrosis induced in a rat model by means of thioacetamide (TAA) administration. The mean liver-to-background radioactivity per unit volume ratio was analyzed for comparisons between the TAA and control (saline) groups at different stages of liver fibrosis. Data were compared by using Student t and Mann-Whitney tests. Results:of SPECT/CT were compared with those of ex vivo biodistribution analysis (n = 5). Accumulation of (99m)Tc-3PRGD2 in the liver increased in proportion to the progression of fibrosis and TAA exposure time; accumulation levels were significantly different between the TAA and control groups as early as week 4 of TAA administration (liver-to-background ratio: 32.30 ± 3.39 vs 19.01 ± 3.31; P = .0002). Results of ex vivo immunofluorescence staining demonstrated the positive expression of integrin αvβ3 on the activated hepatic stellate cells, and the integrin αvβ3 levels in the liver corresponded to the results of SPECT/CT (R(2) = 0.75, P < .0001). (99m)Tc-3PRGD2 uptake in the fibrotic liver decreased after antifibrotic therapy with interferon α2b compared with that in the control group (relative liver-to-background ratio: 0.45 ± 0.05 vs 1.01 ± 0.05; P < .0001) or spontaneous recovery (relative liver-to-background ratio: 0.56 ± 0.06 vs 1.01 ± 0.05; P < .0001). (99m)Tc-3PRGD2 SPECT/CT was successfully used to monitor the progression and recovery of liver fibrosis and shows potential applications for noninvasive diagnosis of early stage liver fibrosis. (©) RSNA, 2015 Online supplemental material is available for this article.

Review Article: Progress in fabrication of transition metal dichalcogenides heterostructure systems

PubMed Central

Dong, Rui; Kuljanishvili, Irma

2017-01-01

Transition metal dichalcogenide (TMDC) semiconductors have attracted significant attention because of their rich electronic/photonic properties and importance for fundamental research and novel device applications. These materials provide a unique opportunity to build up high quality and atomically sharp heterostructures because of the nature of weak van der Waals interlayer interactions. The variable electronic properties of TMDCs (e.g., band gap and their alignment) provide a platform for the design of novel electronic and optoelectronic devices. The integration of TMDC heterostructures into the semiconductor industry is presently hindered by limited options in reliable production methods. Many exciting properties and device architectures which have been studied to date are, in large, based on the exfoliation methods of bulk TMDC crystals. These methods are generally more difficult to consider for large scale integration processes, and hence, continued developments of different fabrication strategies are essential for further advancements in this area. In this review, the authors highlight the recent progress in the fabrication of TMDC heterostructures. The authors will review several methods most commonly used to date for controllable heterostructure formation. One of the focuses will be on TMDC heterostructures fabricated by thermal chemical vapor deposition methods which allow for the control over the resulting materials, individual layers and heterostructures. Another focus would be on the techniques for selective growth of TMDCs. The authors will discuss conventional and unconventional fabrication methods and their advantages and drawbacks and will provide some guidance for future improvements. Mask-assisted and mask-free methods will be presented, which include traditional lithographic techniques (photo- or e-beam lithography) and some unconventional methods such as the focus ion beam and the recently developed direct-write patterning approach, which are shown to be promising for the fabrication of quality TMDC heterostructures. PMID:29075580

Recent progress in thermoelectric nanocomposites based on solution-synthesized nanoheterostructures

DOE PAGES

Zheng, Wei; Xu, Biao; Zhou, Lin; ...

2017-03-27

Thermoelectric materials, which can convert waste heat into electricity, have received increasing interest in these years. This paper describes the recent progress in thermoelectric nanocomposite based on solution-synthesized nanoheterostructures. We start our discussion with the strategies of improving power factor of a given material by using nanoheterostructures. Then we discuss the methods of decreasing thermal conductivity. Finally, we highlight one way to decouple power factor and thermal conductivity, namely, incorporating phase-transition materials into a nanowire heterostructure. We have explored the lead telluride-copper telluride thermoelectric nanowire heterostructure in our group. Future possible ways to improve figure of merit are discussed atmore » the end of this paper.« less

Recent progress in thermoelectric nanocomposites based on solution-synthesized nanoheterostructures

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

Zheng, Wei; Xu, Biao; Zhou, Lin

Thermoelectric materials, which can convert waste heat into electricity, have received increasing interest in these years. This paper describes the recent progress in thermoelectric nanocomposite based on solution-synthesized nanoheterostructures. We start our discussion with the strategies of improving power factor of a given material by using nanoheterostructures. Then we discuss the methods of decreasing thermal conductivity. Finally, we highlight one way to decouple power factor and thermal conductivity, namely, incorporating phase-transition materials into a nanowire heterostructure. We have explored the lead telluride-copper telluride thermoelectric nanowire heterostructure in our group. Future possible ways to improve figure of merit are discussed atmore » the end of this paper.« less

Progress toward determining the potential of ODS alloys for gas turbine applications

NASA Technical Reports Server (NTRS)

Dreshfield, R. L.; Hoppin, G., III; Sheffler, K.

1983-01-01

The Materials for Advanced Turbine Engine (MATE) Program managed by the NASA Lewis Research Center is supporting two projects to evaluate the potential of oxide dispersion strengthened (ODS) alloys for aircraft gas turbine applications. One project involves the evaluation of Incoloy (TM) MA-956 for application as a combustor liner material. An assessment of advanced engine potential will be conducted by means of a test in a P&WA 2037 turbofan engine. The other project involves the evaluation of Inconel (TM) MA 6000 for application as a high pressure turbine blade material and includes a test in a Garrett TFE 731 turbofan engine. Both projects are progressing toward these engine tests in 1984.

IFLA General Conference, 1987. Division of Bibliographic Control. Cataloging Section. Papers.

ERIC Educational Resources Information Center

International Federation of Library Associations, The Hague (Netherlands).

The five papers in this collection focus on bibliographic control: (1) "Developments and Progress in Bibliography" (B. C. Bloomfield, Chairman, Section on Bibliography); (2) "Developments and Progress in Cataloguing" (Tom Delsey, Chairman, Section on Cataloging); (3) "Developments and Progress in Classification and…

Hierarchical ferroelectric and ferrotoroidic polarizations coexistent in nano-metamaterials

PubMed Central

Shimada, Takahiro; Lich, Le Van; Nagano, Koyo; Wang, Jie; Kitamura, Takayuki

2015-01-01

Tailoring materials to obtain unique, or significantly enhanced material properties through rationally designed structures rather than chemical constituents is principle of metamaterial concept, which leads to the realization of remarkable optical and mechanical properties. Inspired by the recent progress in electromagnetic and mechanical metamaterials, here we introduce the concept of ferroelectric nano-metamaterials, and demonstrate through an experiment in silico with hierarchical nanostructures of ferroelectrics using sophisticated real-space phase-field techniques. This new concept enables variety of unusual and complex yet controllable domain patterns to be achieved, where the coexistence between hierarchical ferroelectric and ferrotoroidic polarizations establishes a new benchmark for exploration of complexity in spontaneous polarization ordering. The concept opens a novel route to effectively tailor domain configurations through the control of internal structure, facilitating access to stabilization and control of complex domain patterns that provide high potential for novel functionalities. A key design parameter to achieve such complex patterns is explored based on the parity of junctions that connect constituent nanostructures. We further highlight the variety of additional functionalities that are potentially obtained from ferroelectric nano-metamaterials, and provide promising perspectives for novel multifunctional devices. This study proposes an entirely new discipline of ferroelectric nano-metamaterials, further driving advances in metamaterials research. PMID:26424484

Raloxifene improves skeletal properties in an animal model of cystic chronic kidney disease

PubMed Central

Newman, Christopher L.; Creecy, Amy; Granke, Mathilde; Nyman, Jeffry S.; Tian, Nannan; Hammond, Max A.; Wallace, Joseph M.; Brown, Drew M.; Chen, Neal; Moe, Sharon M.; Allen, Matthew R.

2015-01-01

Patients with chronic kidney disease (CKD) have an increased risk of fracture. Raloxifene is a mild anti-resorptive agent that reduces fracture risk in the general population. Here we assessed the impact of raloxifene on the skeletal properties of animals with progressive CKD. Male Cy/+ rats that develop autosomal dominant cystic kidney disease were treated with either vehicle or raloxifene for five weeks. They were assessed for changes in mineral metabolism and skeletal parameters (microCT, histology, whole bone mechanics, and material properties). Their normal littermates served as controls. Animals with CKD had significantly higher parathyroid hormone levels compared to normal controls as well as inferior structural and mechanical skeletal properties. Raloxifene treatment resulted in lower bone remodeling rates and higher cancellous bone volume in the rats with CKD. While it had little effect on cortical bone geometry it resulted in higher energy to fracture and modulus of toughness values than vehicle-treated rats with CKD, achieving levels equivalent to normal controls. Animals treated with raloxifene had superior tissue-level mechanical properties as assessed by nanoindentation and higher collagen D-periodic spacing as assessed by atomic force microscopy. Thus, raloxifene can positively impact whole bone mechanical properties in CKD through its impact on skeletal material properties. PMID:26489025

A multi-segment soft actuator for biomedical applications based on IPMCs

NASA Astrophysics Data System (ADS)

Zhao, Dongxu; Wang, Yanjie; Liu, Jiayu; Luo, Meng; Li, Dichen; Chen, Hualing

2015-04-01

With rapid progress of biomedical devices towards miniaturization, flexibility, multifunction and low cost, the restrictions of traditional mechanical structures become particularly apparent, while soft materials become research focus in broad fields. As one of the most attractive soft materials, Ionic Polymer-Metal Composite (IPMC) is widely used as artificial muscles and actuators, with the advantages of low driving-voltage, high efficiency of electromechanical transduction and functional stabilization. In this paper, a new intuitive control method was presented to achieve the omnidirectional bending movements and was applied on a representative actuation structure of a multi-degree-offreedom soft actuator composed of two segments bar-shaped IPMC with a square cross section. Firstly, the bar-shaped IPMCs were fabricated by the solution casting method, reducing plating, autocatalytic plating method and cut into shapes successively. The connectors of the multi-segment IPMC actuator were fabricated by 3D printing. Then, a new control method was introduced to realize the intuitive mapping relationship between the actuator and the joystick manipulator. The control circuit was designed and tested. Finally, the multi-degree-of-freedom actuator of 2 segments bar-shaped IPMCs was implemented and omnidirectional bending movements were achieved, which could be a promising actuator for biomedical applications, such as endoscope, catheterism, laparoscopy and the surgical resection of tumors.

Impact cratering experiments in Bingham materials and the morphology of craters on Mars and Ganymede

NASA Technical Reports Server (NTRS)

Fink, J. H.; Greeley, R.; Gault, D. E.

1982-01-01

Results from a series of laboratory impacts into clay slurry targets are compared with photographs of impact craters on Mars and Ganymede. The interior and ejecta lobe morphology of rampart-type craters, as well as the progression of crater forms seen with increasing diameter on both Mars and Ganymede, are equalitatively explained by a model for impact into Bingham materials. For increasing impact energies and constant target rheology, laboratory craters exhibit a morphologic progression from bowl-shaped forms that are typical of dry planetary surfaces to craters with ejecta flow lobes and decreasing interior relief, characteristic of more volatile-rich planets. A similar sequence is seen for uniform impact energy in slurries of decreasing yield strength. The planetary progressions are explained by assuming that volatile-rich or icy planetary surfaces behave locally in the same way as Bingham materials and produce ejecta slurries with yield strenghs and viscosities comparable to terrestrial debris flows. Hypothetical impact into Mars and Ganymede are compared, and it is concluded that less ejecta would be produced on Ganymede owing to its lower gravitational acceleration, surface temperature, and density of surface materials.

Ultrasonic Nondestructive Evaluation Techniques Applied to the Quantitative Characterization of Textile Composite Materials

NASA Technical Reports Server (NTRS)

Miller, James G.

1997-01-01

In this Progress Report, we describe our further development of advanced ultrasonic nondestructive evaluation methods applied to the characterization of anisotropic materials. We present images obtained from experimental measurements of ultrasonic diffraction patterns transmitted through water only and transmitted through water and a thin woven composite. All images of diffraction patterns have been included on the accompanying CD-ROM in the JPEG format and Adobe TM Portable Document Format (PDF), in addition to the inclusion of hardcopies of the images contained in this report. In our previous semi-annual Progress Report (NAG 1-1848, December, 1996), we proposed a simple model to simulate the effect of a thin woven composite on an insonifying ultrasonic pressure field. This initial approach provided an avenue to begin development of a robust measurement method for nondestructive evaluation of anisotropic materials. In this Progress Report, we extend that work by performing experimental measurements on a single layer of a five-harness biaxial woven composite to investigate how a thin, yet architecturally complex, material interacts with the insonifying ultrasonic field. In Section 2 of this Progress Report we describe the experimental arrangement and methods for data acquisition of the ultrasonic diffraction patterns upon transmission through a thin woven composite. We also briefly describe the thin composite specimen investigated. Section 3 details the analysis of the experimental data followed by the experimental results in Section 4. Finally, a discussion of the observations and conclusions is found in Section 5.

Predictors of early neurological deterioration after ischaemic stroke: a case-control study.

PubMed

Barber, Mark; Wright, Fiona; Stott, David J; Langhorne, Peter

2004-01-01

Early neurological deterioration after ischaemic stroke (stroke in progression) is reported to be common and associated with poor outcome or death. The causes of progressing stroke are, however, uncertain. To determine whether prior drug treatment (with anticoagulant or antiplatelet agents) or early adverse physiological features (pyrexia, hypoxia, dehydration or hyperglycaemia) are associated with progressing ischaemic stroke. The study used a case-control design. From a database of 873 consecutive acute stroke admissions, 196 cases of progressing ischaemic stroke (defined by point deterioration in components of the Scandinavian Stroke Scale or death over the first 72 h after hospital admission) were matched to 196 controls on the basis of age and stroke type. Univariate and conditional logistic regression techniques were used to explore predictors of progressing stroke. Cases and controls were well matched for baseline stroke severity. Warfarin use prior to admission was associated with a reduced risk of progressing stroke [odds ratio (OR) 0.10, p = 0.005]. Prior antiplatelet use was not related. A previous history of diabetes (OR 2.11, p = 0.039) and elevated systolic blood pressure on admission (OR 1.01 for each 1 mm Hg rise, p = 0.017) predicted progressing stroke. Although there were no differences in time to presentation or to brain imaging, a visible causative lesion on CT scanning was more common in the progressing stroke group (OR 2.30, p = 0.022). We found no evidence that adverse physiological features were associated with progressing stroke. Outcomes were worse in the progressing stroke group with 70% being dead or dependent by 30 days compared to 55% in the control group (p = 0.002). Prior warfarin use may be protective against progressing ischaemic stroke. A previous history of diabetes along with elevated admission systolic blood pressure predict deterioration. We found no evidence for an association between adverse physiological features and progressing stroke. Copyright 2004 S. Karger AG, Basel

Design for inadvertent damage in composite laminates

NASA Technical Reports Server (NTRS)

Singhal, Surendra N.; Chamis, Christos C.

1992-01-01

Simplified predictive methods and models to computationally simulate durability and damage in polymer matrix composite materials/structures are described. The models include (1) progressive fracture, (2) progressively damaged structural behavior, (3) progressive fracture in aggressive environments, (4) stress concentrations, and (5) impact resistance. Several examples are included to illustrate applications of the models and to identify significant parameters and sensitivities. Comparisons with limited experimental data are made.

Control of DNA hybridization by photoswitchable molecular glue.

PubMed

Dohno, Chikara; Nakatani, Kazuhiko

2011-12-01

Hybridization of DNA is one of the most intriguing events in molecular recognition and is essential for living matter to inherit life beyond generations. In addition to the function of DNA as genetic material, DNA hybridization is a key to control the function of DNA-based materials in nanoscience. Since the hybridization of two single stranded DNAs is a thermodynamically favorable process, dissociation of the once formed DNA duplex is normally unattainable under isothermal conditions. As the progress of DNA-based nanoscience, methodology to control the DNA hybridization process has become increasingly important. Besides many reports using the chemically modified DNA for the regulation of hybridization, we focused our attention on the use of a small ligand as the molecular glue for the DNA. In 2001, we reported the first designed molecule that strongly and specifically bound to the mismatched base pairs in double stranded DNA. Further studies on the mismatch binding molecules provided us a key discovery of a novel mode of the binding of a mismatch binding ligand that induced the base flipping. With these findings we proposed the concept of molecular glue for DNA for the unidirectional control of DNA hybridization and, eventually photoswitchable molecular glue for DNA, which enabled the bidirectional control of hybridization under photoirradiation. In this tutorial review, we describe in detail how we integrated the mismatch binding ligand into photoswitchable molecular glue for DNA, and the application and perspective in DNA-based nanoscience.

Lewis materials research and technology: An overview

NASA Technical Reports Server (NTRS)

Grisaffe, Salvatore J.

1987-01-01

The Materials Division at the Lewis Research Center has a long record of contributions to both materials and process technology as well as to the understanding of key high-temperature phenomena. An overview of the division staff, facilities, past history, recent progress, and future interests is presented.

NASA. Lewis Research Center materials research and technology: An overview

NASA Technical Reports Server (NTRS)

Grisaffe, Salvatore J.

1990-01-01

The Materials Division at the Lewis Research Center has a long record of contributions to both materials and process technology as well as to the understanding of key high-temperature phenomena. This paper overviews the division staff, facilities, past history, recent progress, and future interests.

Losses in Ferroelectric Materials

PubMed Central

Liu, Gang; Zhang, Shujun; Jiang, Wenhua; Cao, Wenwu

2015-01-01

Ferroelectric materials are the best dielectric and piezoelectric materials known today. Since the discovery of barium titanate in the 1940s, lead zirconate titanate ceramics in the 1950s and relaxor-PT single crystals (such as lead magnesium niobate-lead titanate and lead zinc niobate-lead titanate) in the 1980s and 1990s, perovskite ferroelectric materials have been the dominating piezoelectric materials for electromechanical devices, and are widely used in sensors, actuators and ultrasonic transducers. Energy losses (or energy dissipation) in ferroelectrics are one of the most critical issues for high power devices, such as therapeutic ultrasonic transducers, large displacement actuators, SONAR projectors, and high frequency medical imaging transducers. The losses of ferroelectric materials have three distinct types, i.e., elastic, piezoelectric and dielectric losses. People have been investigating the mechanisms of these losses and are trying hard to control and minimize them so as to reduce performance degradation in electromechanical devices. There are impressive progresses made in the past several decades on this topic, but some confusions still exist. Therefore, a systematic review to define related concepts and clear up confusions is urgently in need. With this objective in mind, we provide here a comprehensive review on the energy losses in ferroelectrics, including related mechanisms, characterization techniques and collections of published data on many ferroelectric materials to provide a useful resource for interested scientists and engineers to design electromechanical devices and to gain a global perspective on the complex physical phenomena involved. More importantly, based on the analysis of available information, we proposed a general theoretical model to describe the inherent relationships among elastic, dielectric, piezoelectric and mechanical losses. For multi-domain ferroelectric single crystals and ceramics, intrinsic and extrinsic energy loss mechanisms are discussed in terms of compositions, crystal structures, temperature, domain configurations, domain sizes and grain boundaries. The intrinsic and extrinsic contributions to the total energy dissipation are quantified. In domain engineered ferroelectric single crystals and ceramics, polarization rotations, domain wall motions and mechanical wave scatterings at grain boundaries are believed to control the mechanical quality factors of piezoelectric resonators. We show that a thorough understanding on the kinetic processes is critical in analyzing energy loss behavior and other time-dependent properties in ferroelectric materials. At the end of the review, existing challenges in the study and control of losses in ferroelectric materials are analyzed, and future perspective in resolving these issues is discussed. PMID:25814784

Losses in Ferroelectric Materials.

PubMed

Liu, Gang; Zhang, Shujun; Jiang, Wenhua; Cao, Wenwu

2015-03-01

Ferroelectric materials are the best dielectric and piezoelectric materials known today. Since the discovery of barium titanate in the 1940s, lead zirconate titanate ceramics in the 1950s and relaxor-PT single crystals (such as lead magnesium niobate-lead titanate and lead zinc niobate-lead titanate) in the 1980s and 1990s, perovskite ferroelectric materials have been the dominating piezoelectric materials for electromechanical devices, and are widely used in sensors, actuators and ultrasonic transducers. Energy losses (or energy dissipation) in ferroelectrics are one of the most critical issues for high power devices, such as therapeutic ultrasonic transducers, large displacement actuators, SONAR projectors, and high frequency medical imaging transducers. The losses of ferroelectric materials have three distinct types, i.e., elastic, piezoelectric and dielectric losses. People have been investigating the mechanisms of these losses and are trying hard to control and minimize them so as to reduce performance degradation in electromechanical devices. There are impressive progresses made in the past several decades on this topic, but some confusions still exist. Therefore, a systematic review to define related concepts and clear up confusions is urgently in need. With this objective in mind, we provide here a comprehensive review on the energy losses in ferroelectrics, including related mechanisms, characterization techniques and collections of published data on many ferroelectric materials to provide a useful resource for interested scientists and engineers to design electromechanical devices and to gain a global perspective on the complex physical phenomena involved. More importantly, based on the analysis of available information, we proposed a general theoretical model to describe the inherent relationships among elastic, dielectric, piezoelectric and mechanical losses. For multi-domain ferroelectric single crystals and ceramics, intrinsic and extrinsic energy loss mechanisms are discussed in terms of compositions, crystal structures, temperature, domain configurations, domain sizes and grain boundaries. The intrinsic and extrinsic contributions to the total energy dissipation are quantified. In domain engineered ferroelectric single crystals and ceramics, polarization rotations, domain wall motions and mechanical wave scatterings at grain boundaries are believed to control the mechanical quality factors of piezoelectric resonators. We show that a thorough understanding on the kinetic processes is critical in analyzing energy loss behavior and other time-dependent properties in ferroelectric materials. At the end of the review, existing challenges in the study and control of losses in ferroelectric materials are analyzed, and future perspective in resolving these issues is discussed.

Two-Dimensional Semiconductor Optoelectronics Based on van der Waals Heterostructures.

PubMed

Lee, Jae Yoon; Shin, Jun-Hwan; Lee, Gwan-Hyoung; Lee, Chul-Ho

2016-10-27

Two-dimensional (2D) semiconductors such as transition metal dichalcogenides (TMDCs) and black phosphorous have drawn tremendous attention as an emerging optical material due to their unique and remarkable optical properties. In addition, the ability to create the atomically-controlled van der Waals (vdW) heterostructures enables realizing novel optoelectronic devices that are distinct from conventional bulk counterparts. In this short review, we first present the atomic and electronic structures of 2D semiconducting TMDCs and their exceptional optical properties, and further discuss the fabrication and distinctive features of vdW heterostructures assembled from different kinds of 2D materials with various physical properties. We then focus on reviewing the recent progress on the fabrication of 2D semiconductor optoelectronic devices based on vdW heterostructures including photodetectors, solar cells, and light-emitting devices. Finally, we highlight the perspectives and challenges of optoelectronics based on 2D semiconductor heterostructures.

Continuous monitoring of the progressive degradation of a liquid composite by means of a noninvasive microwave resonator

NASA Astrophysics Data System (ADS)

Catala-Civera, Jose M.; Canos-Marin, Antoni J.; de los Reyes, E.

2000-07-01

Microwave control capabilities have been used to monitor the degradation of polyol, an alcohol composite material commonly used in the footwear industry for polymerization purposes. The liquid flows continuously inside a thin pipe and its desirable properties are altered with time associated to moisture absorption processes. Consequently, variations in the dielectric properties are involved, and they can be detected by permittivity measurements. In this paper, in order to obtain high sensitivity and resolution, a rectangular cavity resonator working at a fixed frequency was designed using as sample holder a rectangular pipe containing the liquid going through. Changes in the liquid modify the original response of the cavity with a non- degraded liquid and these differences have been used to determine the degree of degradation of the material. The final response of the microwave resonator was experimentally validated with measurements in a continuous line.

Two-Dimensional Semiconductor Optoelectronics Based on van der Waals Heterostructures

PubMed Central

Lee, Jae Yoon; Shin, Jun-Hwan; Lee, Gwan-Hyoung; Lee, Chul-Ho

2016-01-01

Two-dimensional (2D) semiconductors such as transition metal dichalcogenides (TMDCs) and black phosphorous have drawn tremendous attention as an emerging optical material due to their unique and remarkable optical properties. In addition, the ability to create the atomically-controlled van der Waals (vdW) heterostructures enables realizing novel optoelectronic devices that are distinct from conventional bulk counterparts. In this short review, we first present the atomic and electronic structures of 2D semiconducting TMDCs and their exceptional optical properties, and further discuss the fabrication and distinctive features of vdW heterostructures assembled from different kinds of 2D materials with various physical properties. We then focus on reviewing the recent progress on the fabrication of 2D semiconductor optoelectronic devices based on vdW heterostructures including photodetectors, solar cells, and light-emitting devices. Finally, we highlight the perspectives and challenges of optoelectronics based on 2D semiconductor heterostructures. PMID:28335321

Spectral mapping of thermal conductivity through nanoscale ballistic transport

NASA Astrophysics Data System (ADS)

Hu, Yongjie; Zeng, Lingping; Minnich, Austin J.; Dresselhaus, Mildred S.; Chen, Gang

2015-08-01

Controlling thermal properties is central to many applications, such as thermoelectric energy conversion and the thermal management of integrated circuits. Progress has been made over the past decade by structuring materials at different length scales, but a clear relationship between structure size and thermal properties remains to be established. The main challenge comes from the unknown intrinsic spectral distribution of energy among heat carriers. Here, we experimentally measure this spectral distribution by probing quasi-ballistic transport near nanostructured heaters down to 30 nm using ultrafast optical spectroscopy. Our approach allows us to quantify up to 95% of the total spectral contribution to thermal conductivity from all phonon modes. The measurement agrees well with multiscale and first-principles-based simulations. We further demonstrate the direct construction of mean free path distributions. Our results provide a new fundamental understanding of thermal transport and will enable materials design in a rational way to achieve high performance.

High Performance Perovskite Solar Cells

PubMed Central

Tong, Xin; Lin, Feng; Wu, Jiang

2015-01-01

Perovskite solar cells fabricated from organometal halide light harvesters have captured significant attention due to their tremendously low device costs as well as unprecedented rapid progress on power conversion efficiency (PCE). A certified PCE of 20.1% was achieved in late 2014 following the first study of long‐term stable all‐solid‐state perovskite solar cell with a PCE of 9.7% in 2012, showing their promising potential towards future cost‐effective and high performance solar cells. Here, notable achievements of primary device configuration involving perovskite layer, hole‐transporting materials (HTMs) and electron‐transporting materials (ETMs) are reviewed. Numerous strategies for enhancing photovoltaic parameters of perovskite solar cells, including morphology and crystallization control of perovskite layer, HTMs design and ETMs modifications are discussed in detail. In addition, perovskite solar cells outside of HTMs and ETMs are mentioned as well, providing guidelines for further simplification of device processing and hence cost reduction. PMID:27774402

Effectiveness of silica based sol-gel microencapsulation method for odorants and flavors leading to sustainable environment

PubMed Central

Ashraf, Muhammad Aqeel; Khan, Aysha Masood; Ahmad, Mushtaq; Sarfraz, Maliha

2015-01-01

Microencapsulation has become a hot topic in chemical research. Technology mainly used for control release and protection purposes. The sol-gel micro encapsulation approach for fragrance and aroma in porous silica-based materials leads to sustainable odorant and flavored materials with novel and unique beneficial properties. Sol-gel encapsulation of silica based micro particles considered economically cheap as capital investment in manufacturing is very low and environmentally friendly. Amorphous sol-gel SiO2 is non-toxic and safe, whereas the sol-gel entrapment of delicate chemicals in its inner pores results in pronounced chemical and physical stabilization of the entrapped active agents, thereby broadening the practical utilization of chemically unstable essential oils (EOs). Reviewing progress in the fabrication of diverse odorant and flavored sol-gels, shows us how different synthetic strategies are appropriate for practical application with important health and environmental benefits. PMID:26322304

Effectiveness of silica based sol-gel microencapsulation method for odorants and flavors leading to sustainable environment.

PubMed

Ashraf, Muhammad Aqeel; Khan, Aysha Masood; Ahmad, Mushtaq; Sarfraz, Maliha

2015-01-01

Microencapsulation has become a hot topic in chemical research. Technology mainly used for control release and protection purposes. The sol-gel micro encapsulation approach for fragrance and aroma in porous silica-based materials leads to sustainable odorant and flavored materials with novel and unique beneficial properties. Sol-gel encapsulation of silica based micro particles considered economically cheap as capital investment in manufacturing is very low and environmentally friendly. Amorphous sol-gel SiO2 is non-toxic and safe, whereas the sol-gel entrapment of delicate chemicals in its inner pores results in pronounced chemical and physical stabilization of the entrapped active agents, thereby broadening the practical utilization of chemically unstable essential oils (EOs). Reviewing progress in the fabrication of diverse odorant and flavored sol-gels, shows us how different synthetic strategies are appropriate for practical application with important health and environmental benefits.

Nondestructive Evaluation Techniques for Development and Characterization of Carbon Nanotube Based Superstructures

NASA Technical Reports Server (NTRS)

Wincheski, Buzz; Kim, Jae-Woo; Sauti, Godfrey; Wainwright, Elliot; Williams, Phillip; Siochi, Emile J.

2014-01-01

Recently, multiple commercial vendors have developed capability for the production of large-scale quantities of high-quality carbon nanotube sheets and yarns. While the materials have found use in electrical shielding applications, development of structural systems composed of a high volume fraction of carbon nanotubes is still lacking. A recent NASA program seeks to address this by prototyping a structural nanotube composite with strength-toweight ratio exceeding current state-of-the-art carbon fiber composites. Commercially available carbon nanotube sheets, tapes, and yarns are being processed into high volume fraction carbon nanotube-polymer nanocomposites. Nondestructive evaluation techniques have been applied throughout this development effort for material characterization and process control. This paper will report on the progress of these efforts, including magnetic characterization of residual catalyst content, Raman scattering characterization of nanotube diameter, defect ratio, and nanotube strain, and polarized Raman scattering for characterization of nanotube alignment.

CELSS Transportation Analysis

NASA Technical Reports Server (NTRS)

Olson, R. L.; Gustan, E. A.; Vinopal, T. J.

1985-01-01

Regenerative life support systems based on the use of biological material was considered for inclusion in manned spacecraft. Biological life support systems are developed in the controlled ecological life support system (CELSS) program. Because of the progress achieved in the CELSS program, it is determined which space missions may profit from use of the developing technology. Potential transportation cost savings by using CELSS technology for selected future manned space missions was evaluated. Six representative missions were selected which ranged from a low Earth orbit mission to those associated with asteroids and a Mars sortie. The crew sizes considered varied from four persons to five thousand. Other study parameters included mission duration and life support closure percentages, with the latter ranging from complete resupply of consumable life support materials to 97% closure of the life support system. The analytical study approach and the missions and systems considered, together with the benefits derived from CELSS when applicable are described.

Progress Towards the Development of a Long-Lived Venus Lander Duplex System

NASA Technical Reports Server (NTRS)

Dyson, Roger W.; Bruder, Geoffrey A.

2010-01-01

NASA has begun the development of a combined Stirling cycle power and cooling system (duplex) to enable the long-lived surface exploration of Venus and other harsh environments in the solar system. The duplex system will operate from the heat provided by decaying radioisotope plutonium-238 or its substitute. Since the surface of Venus has a thick, hot, and corrosive atmosphere, it is a challenging proposition to maintain sensitive lander electronics under survivable conditions. This development effort requires the integration of: a radioisotope or fission heat source; heat pipes; high-temperature, corrosion-resistant material; multistage cooling; a novel free-displacer Stirling convertor for the lander; and a minimal vibration thermoacoustic Stirling convertor for the seismometer. The first year effort includes conceptual system design and control studies, materials development, and prototype hardware testing. A summary of these findings and test results is presented in this report.

Progress Towards the Development of a Long-Lived Venus Lander Duplex System

NASA Technical Reports Server (NTRS)

Dyson, Rodger, W.; Bruder, Geoffrey A.

2011-01-01

NASA has begun the development of a combined Stirling cycle power and cooling system (duplex) to enable the long-lived surface exploration of Venus and other harsh environments in the solar system. The duplex system will operate from the heat provided by decaying radioisotope plutonium-238 or its substitute. Since the surface of Venus has a thick, hot, and corrosive atmosphere, it is a challenging proposition to maintain sensitive lander electronics under survivable conditions. This development effort requires the integration of: a radioisotope or fission heat source; heat pipes; high-temperature, corrosion-resistant material; multistage cooling; a novel free-displacer Stirling convertor for the lander; and a minimal vibration thermoacoustic Stirling convertor for the seismometer. The first year effort includes conceptual system design and control studies, materials development, and prototype hardware testing. A summary of these findings and test results is presented in this report.

Silicon solar cell process development, fabrication, and analysis

NASA Technical Reports Server (NTRS)

Yoo, H. I.; Iles, P. A.; Leung, D. C.

1981-01-01

Work has progressed in fabrication and characterization of solar cells from ubiquitous crystallization process (UCP) wafers and LASS ribbons. Gettering tests applied to UCP wafers made little change on their performance compared with corresponding baseline data. Advanced processes such as shallow junction (SJ), back surface field (BSF), and multilayer antireflection (MLAR) were also applied. While BSF by Al paste had shunting problems, cells with SJ and BSF by evaporated Al, and MLAR did achieve 14.1% AMI on UCP silicon. The study of LASS material was very preliminary. Only a few cells with SJ, BSR, (no BSF) and MLAR were completed due to mechanical yield problems after lapping the material. Average efficiency was 10.7% AMI with 13.4% AMI for CZ controls. Relatively high minority carrier diffusion lengths were obtained. The lower than expected Jsc could be partially explained by low active area due to irregular sizes.

Environmental barrier coating (EBC) durability modeling using a progressive failure analysis approach

NASA Astrophysics Data System (ADS)

Abdul-Aziz, Ali; Abumeri, Galib; Troha, William; Bhatt, Ramakrishna T.; Grady, Joseph E.; Zhu, D.

2012-04-01

Ceramic matrix composites (CMCs) are getting the attention of most engine manufacturers and aerospace firms for turbine engine and other related applications. This is because of their potential weight advantage and performance benefits. As a protecting guard for these materials, a highly specialized form of environmental barrier coating (EBC) is being developed and explored for high temperature applications that are greater than 1100 °C1,2. The EBCs are typically a multilayer of coatings and are on the order of hundreds of microns thick. CMCs are generally porous materials and this feature is somewhat beneficial since it allows some desirable infiltration of the EBC. Their degradation usually includes coating interface oxidation as opposed to moisture induced matrix degradation which is generally seen at a higher temperature. A variety of factors such as residual stresses, coating process related flaws, and casting conditions may influence the strength of degradation. The cause of such defects which cause cracking and other damage is that not much energy is absorbed during fracture of these materials. Therefore, an understanding of the issues that control crack deflection and propagation along interfaces is needed to maximize the energy dissipation capabilities of layered ceramics. Thus, evaluating components and subcomponents made out of CMCs under gas turbine engine conditions is suggested to demonstrate that these material will perform as expected and required under these aggressive environmental circumstances. Progressive failure analysis (PFA) is applied to assess the damage growth of the coating under combined thermal and mechanical loading conditions. The PFA evaluation is carried out using a full-scale finite element model to account for the average material failure at the microscopic or macroscopic levels. The PFA life prediction evaluation identified the root cause for damage initiation and propagation. It indicated that delamination type damage initiated mainly in the bond and intermediate coating materials then propagated to the substrate. Results related to damage initiation and propagation; behavior and life assessment of the coating at the interface of the EBC/CMC are presented and discussed.

Solid State Division annual progress report for period ending December 31, 1975

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

Wilkinson, M.K.; Young, F.W. Jr.

1976-05-01

Research activities are reported in programs on theoretical solid state physics, physical properties of solids, radiation effects in metals, neutron scattering, research materials, and isotope research materials. (JRD)

29 CFR 1917.11 - Housekeeping.

Code of Federal Regulations, 2010 CFR

2010-07-01

... sharp objects not necessary for the work in progress. (b) Hatch beams, covers and pontoons placed in..., dunnage or other suitable material shall be used under and between tiers. (c) Cargo and material shall not...

Sonoproduction of liposomes and protein particles as templates for delivery purposes.

PubMed

Silva, Raquel; Ferreira, Helena; Cavaco-Paulo, Artur

2011-10-10

The development of nano and micro delivery systems (DS), so small in size, is growing in importance, such as in drug targeting. In an era where nano is the new trend, micro and nano materials are in the forefront of progress. These systems can be produced by a diversity of methods. However, the use of high-intensity ultrasound offers an easy and versatile tool for nano- and microstructured materials that are often unavailable by conventional methods. Similarly to the synthesis methods that can be used, several starting materials can be applied to produce particulate systems. In this review, the recent strategic development of DS is discussed with emphasis on liposomes and polymer-based, specially protein-based, nanomedicine platforms for drug delivery. Among the variety of applications that materials in the particulate form can have, the control release of drugs is probably the most prominent one, as these have been in the forefront line of interest for biomedical applications. The basic concepts of sonochemical process pertaining to DS are summarized as well as the role of sonochemical procedure to their preparation. The different applications of these systems wrap up this review.

Emergent 1d Ising Behavior in AN Elementary Cellular Automaton Model

NASA Astrophysics Data System (ADS)

Kassebaum, Paul G.; Iannacchione, Germano S.

The fundamental nature of an evolving one-dimensional (1D) Ising model is investigated with an elementary cellular automaton (CA) simulation. The emergent CA simulation employs an ensemble of cells in one spatial dimension, each cell capable of two microstates interacting with simple nearest-neighbor rules and incorporating an external field. The behavior of the CA model provides insight into the dynamics of coupled two-state systems not expressible by exact analytical solutions. For instance, state progression graphs show the causal dynamics of a system through time in relation to the system's entropy. Unique graphical analysis techniques are introduced through difference patterns, diffusion patterns, and state progression graphs of the 1D ensemble visualizing the evolution. All analyses are consistent with the known behavior of the 1D Ising system. The CA simulation and new pattern recognition techniques are scalable (in both dimension, complexity, and size) and have many potential applications such as complex design of materials, control of agent systems, and evolutionary mechanism design.

Past, Recent Progresses and Future Perspectives of Nanotechnology Applied to Antifungal Agents.

PubMed

Roque, Luis; Molpeceres, Jesus; Reis, Claudia; Rijo, Patrícia; Reis, Catarina Pinto

2017-01-01

Candida species remain a significant cause of nosocomial bloodstream infections, associated with prolonged hospital stay in the ICU and high healthcare cost. The incidence of Candida is very high in certain risk groups of patients (AIDS, diabetes, cancer, etc.). Recent developments of nanotechnology have strongly contributed to the design of new multifunctional drug carriers that improve drug bioavailability through a controlled and prolonged release profile or even through a more specific targeted delivery of the antifungal agent. Those types of systems have strongly increased with a progressive generation of new structures, permitting the conjunction of new materials, biomolecules, physical and chemical techniques, for better outcomes. Nanotechnology shows expanded possibilities within the medical field and in the case of the yeast infections it may overcome several issues related with the fungal proliferation or higher inhibition of the pathogen causing the infection. This review covers a period of the most representative research of Candidiasis since 1993 to the present. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Failure to detect genomic material of HTLV-I or HTLV-II in mononuclear cells of Italian patients with multiple sclerosis and chronic progressive myelopathy.

PubMed

Merelli, E; Sola, P; Marasca, R; Salati, R; Torelli, G

1993-01-01

To contribute to the undecided question if a retrovirus of the human T-cell lymphotropic virus (HTLV) family may be involved in the development of multiple sclerosis (MS), we investigated by the polymerase chain reaction (PCR) the presence of HTLV-I and HTLV-II sequences in the peripheral blood mononuclear cell DNAs from 30 patients affected by MS and 15 by chronic progressive myelopathy. Moreover a control group of 14 blood donors was examined. All these patients were devoid of anti-HTLV-I antibody in the serum and cerebrospinal fluid at ELISA. For the PCR, primers and probes specific for the tax region common to HTLV-I and HTLV-II, for the pol region of HTLV-I, and for the pol region of HTLV-II were used. In spite of the high sensitivity of the technique used, the three groups of subjects were negative for HTLV-I and HTLV-II genomic sequences.

Associations Between Neutrophil Gelatinase Associated Lipocalin, Neutrophil-to-Lymphocyte Ratio, Atrial Fibrillation and Renal Dysfunction in Chronic Heart Failure

PubMed Central

Argan, Onur; Ural, Dilek; Kozdag, Guliz; Sahin, Tayfun; Bozyel, Serdar; Aktas, Mujdat; Karauzum, Kurtulus; Yılmaz, Irem; Dervis, Emir; Agir, Aysen

2016-01-01

Background Atrial fibrillation (AF) and renal dysfunction are two common comorbidities in patients with chronic heart failure with reduced ejection fraction (HFrEF). This study evaluated the effect of permanent AF on renal function in HFrEF and investigated the associations of atrial fibrillation, neutrophil gelatinase-associated lipocalin (NGAL), and neutrophil-to-lymphocyte ratio (NLR) with adverse clinical outcome. Material/Methods Serum NGAL levels measured by ELISA and NLR were compared between patients with sinus rhythm (HFrEF-SR, n=68), with permanent AF (HFrEF-AF, n=62), and a healthy control group (n=50). Results Mean eGFR levels were significantly lower, and NLR and NGAL levels were significantly higher in the HFrEF patients than in the control patients but the difference between HFrEF-SR and HFrEF-AF was not statistically significant (NGAL: 95 ng/mL in HFrEF-SR, 113 ng/mL in HFrEF-AF and 84 ng/mL in the control group; p<0.001). Independent associates of baseline eGFR were age, hemoglobin, NLR, triiodothyronine, and pulmonary artery systolic pressure. In a mean 16 months follow-up, adverse clinical outcome defined as progression of kidney dysfunction and composite of all-cause mortality and re-hospitalization were not different between HFrEF-SR and HFrEF-AF patients. Although NGAL was associated with clinical endpoints in the univariate analysis, Cox regression analysis showed that independent predictors of increased events were the presence of signs right heart failure, C-reactive protein, NLR, triiodothyronine, and hemoglobin. In ROC analysis, a NLR >3 had a 68% sensitivity and 75% specificity to predict progression of kidney disease (AUC=0.72, 95% CI 0.58–0.85, p=0.001). Conclusions Presence of AF in patients with HFrEF was not an independent contributor of adverse clinical outcome (i.e., all-cause death, re-hospitalization) or progression of renal dysfunction. Renal dysfunction in HFrEF was associated with both NLR and NGAL levels, but systemic inflammation reflected by NLR seemed to be a more important determinant of progression of kidney dysfunction. PMID:27918494

FY 2012 Lightweight Materials Annual Report

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

Warren, David C.

2013-04-15

The FY 2012 Annual Progress Report for Lightweight Materials provides a detailed description of the activities and technical accomplishments which focuses on the development and validation of advanced materials and manufacturing technologies to significantly reduce light and heavy duty vehicle weight without compromising other attributes such as safety, performance, recyclability, and cost.

40 CFR 52.2037 - Control strategy plans for attainment and rate-of-progress: Ozone.

Code of Federal Regulations, 2012 CFR

2012-07-01

... and rate-of-progress: Ozone. 52.2037 Section 52.2037 Protection of Environment ENVIRONMENTAL... (CONTINUED) Pennsylvania § 52.2037 Control strategy plans for attainment and rate-of-progress: Ozone. (a) Part D—Conditional Approval—the Pennsylvania plan for carbon monoxide and ozone is approved provided...

40 CFR 52.2037 - Control strategy plans for attainment and rate-of-progress: Ozone.

Code of Federal Regulations, 2013 CFR

2013-07-01

... and rate-of-progress: Ozone. 52.2037 Section 52.2037 Protection of Environment ENVIRONMENTAL... (CONTINUED) Pennsylvania § 52.2037 Control strategy plans for attainment and rate-of-progress: Ozone. (a) Part D—Conditional Approval—the Pennsylvania plan for carbon monoxide and ozone is approved provided...

40 CFR 52.2037 - Control strategy plans for attainment and rate-of-progress: Ozone.

Code of Federal Regulations, 2010 CFR

2010-07-01

... and rate-of-progress: Ozone. 52.2037 Section 52.2037 Protection of Environment ENVIRONMENTAL... (CONTINUED) Pennsylvania § 52.2037 Control strategy plans for attainment and rate-of-progress: Ozone. (a) Part D—Conditional Approval—the Pennsylvania plan for carbon monoxide and ozone is approved provided...

40 CFR 52.2037 - Control strategy plans for attainment and rate-of-progress: Ozone.

Code of Federal Regulations, 2011 CFR

2011-07-01

... and rate-of-progress: Ozone. 52.2037 Section 52.2037 Protection of Environment ENVIRONMENTAL... (CONTINUED) Pennsylvania § 52.2037 Control strategy plans for attainment and rate-of-progress: Ozone. (a) Part D—Conditional Approval—the Pennsylvania plan for carbon monoxide and ozone is approved provided...

Dielectric Property Enhancement in Polymer Composites with Engineered Interfaces

NASA Astrophysics Data System (ADS)

Krentz, Timothy Michael

This thesis reports studies into the dielectric behavior of polymer composites filled with silica nanoparticles. The permittivity and dielectric breakdown strength (DBS) of these materials are critical to their performance in insulating applications such as high voltage power transmission. Until now, the mechanisms which lead to improvements in DBS in these systems have been poorly understood, in part because the effects of dispersion of the filler and the filler's surface electronic characteristics have been confused. The new surface modifications created in this thesis permit these two parameters to be addressed independently, leading to the hypothesis that nanocomposite dielectric materials exhibit DBS enhancement when electron avalanches are prevented from proceeding to reach a critical size capable of causing failure. The same control of dispersion and surface properties also lead to changes in the permittivity of the composite based upon the polarizability and trapping behavior of the filler. In this work, the dispersion and surface states of silica nanoparticles were independently controlled with two separate populations of surface molecules. Two matrix materials were studied, and in each system, a different, matrix-compatible long chain polymer is required to control dispersion. Conversely, a second population of short molecules is shown to be capable of creating electronic traps associated with the silica nanoparticle surface which lead to DBS enhancements largely independent of the matrix, indicating that the same failure mechanism is operating in both epoxy and polypropylene. Progressive variation in dispersion quality is attained with this surface modification scheme. This creates progressively smaller volumes of matrix polymer unaffected by the filler. This work shows that when these volumes approach and become smaller than the same scale as predicted for electron avalanches, the greatest changes in DBS are seen. Likewise, the plateau behavior of this data implicates that the DBS improvements occur as avalanches are halted in their early phases by the filler, before sufficiently energy can be gathered to damage the matrix. These data indicate that avalanche sizes on the order of 150 nm are sufficient to lead to failure. Furthermore, the depths of the traps induced by small molecules on the silica surface are shown to relate to the DBS enhancement obtained for well dispersed fillers based upon the ability of these localized traps to absorb the energy gathered by growing avalanches.

Preliminary experience with a new device for delayed sternal closure strategy in cardiac surgery.

PubMed

Santini, Francesco; Onorati, Francesco; Telesca, Mariassunta; Faggian, Giuseppe; Mazzucco, Alessandro

2012-06-01

Open chest management with delayed sternal closure (DSC) is a valuable strategy in the management of patients with postcardiotomy hemodynamic instability or severe coagulopathy. The conventional extemporized material available for off-label sternal stenting however may limit its efficacy. We evaluated outcomes of patients with refractory severe postcardiotomy cardiogenic shock (SPCCS) treated with DSC using a novel temporary sternal spreader (NTSS) which allows myocardial recovery by progressive controlled approximation of the sternal edges. Seven patients (4 male, mean age 66.5 ± 5 years) with refractory SPCCS showing acute hemodynamic instability at sternal closure, were implanted with the NTSS, consisting of stainless-steel branches linked to 2 diverging plates of polyether-ether ketone, whose progressive opening/closing mechanism can be controlled from outside the chest with a rotating steel wire. The sternal wound was closed by an elastic membrane to achieve a sterile field. Swan-Ganz monitoring was employed, and clinical outcomes evaluated. The device was successfully implanted in all patients without device-related complications or failures. Progressive approximation of sternal edges, titrated on cardiac index values, was successfully completed allowing subsequent uneventful sternal closure in all. Mean time from SPCCS to sternal closure was 70 ± 21 hours. No patient developed infective complications or late hemodynamic instability after device removal and sternal closure. One patient (14%) died of multiorgan failure on postoperative day 9. Despite the limited number of patients enrolled, the NTSS proved safe and effective in allowing complete myocardial recovery after SPCCS, avoiding hemodynamic instability related to abrupt sternal closure, with no occurrence of infective complications.

Costus spicatus tea failed to improve diabetic progression in C57BLKS/J db/db mice, a model of type 2 diabetes mellitus

PubMed Central

Keller, Amy C.; Vandebroek, Ina; Liu, Youping; Balick, Michael J.; Kronenberg, Fredi; Kennelly, Edward J.; Brillantes, Anne-Marie B.

2009-01-01

Aim of the study Costus spicatus Sw. (Costaceae) is a prominent medicinal herb used by Dominicans in the Dominican Republic and the United States for the treatment of diabetes, a growing epidemic in the Hispanic community. An ethnobotanical survey of the Dominican community in New York City revealed the popular use of a tea from the insulina plant to treat hyperglycemia. Insulina was identified as Costus spicatus. We tested the ability of a tea made from the leaves of Costus spicatus to alter glucose homeostasis in C57BLKS/J (KS) db/db mice, a model of obesity-induced hyperglycemia with progressive beta cell depletion. Materials and methods From 6 to 16 weeks of age, Experimental and Control animals (n = 6/5) were given ad lib access to Costus spicatus tea or water, respectively. Results Weight gain and progression of hyperglycemia and insulinopenia between the Experimental and Control groups were statistically indistinguishable. There was no difference between groups in average fed or fasting glucose and insulin concentrations. Intraperitoneal (IP) insulin tolerance testing after the 10-week study period showed that Costus spicatus tea consumption did not alter insulin sensitivity. Conclusions These data suggest that at the dose given, tea made from Costus spicatus leaves had no efficacy in the treatment of obesity-induced hyperglycemia. More investigation is needed to more fully explore dosages and the possible utility and biological activity of this common Dominican herbal remedy for the treatment of type 2 diabetes mellitus. PMID:19027842

Biomimetic photo-actuation: progress and challenges

NASA Astrophysics Data System (ADS)

Dicker, Michael P. M.; Weaver, Paul M.; Rossiter, Jonathan M.; Bond, Ian P.; Faul, Charl F. J.

2016-04-01

Photo-actuation, such as that observed in the reversible sun-tracking movements of heliotropic plants, is produced by a complex, yet elegant series of processes. In the heliotropic leaf movements of the Cornish Mallow, photo-actuation involves the generation, transport and manipulation of chemical signals from a distributed network of sensors in the leaf veins to a specialized osmosis driven actuation region in the leaf stem. It is theorized that such an arrangement is both efficient in terms of materials use and operational energy conversion, as well as being highly robust. We concern ourselves with understanding and mimicking these light driven, chemically controlled actuating systems with the aim of generating intelligent structures which share the properties of efficiency and robustness that are so important to survival in Nature. In this work we present recent progress in mimicking these photo-actuating systems through remote light exposure of a metastable state photoacid and the resulting signal and energy transfer through solution to a pH-responsive hydrogel actuator. Reversible actuation strains of 20% were achieved from this arrangement, with modelling then employed to reveal the critical influence hydrogel pKa has on this result. Although the strong actuation achieved highlights the progress that has been made in replicating the principles of biomimetic photo-actuation, challenges such as photoacid degradation were also revealed. It is anticipated that current work can directly lead to the development of high-performance and low-cost solartrackers for increased photovoltaic energy capture and to the creation of new types of intelligent structures employing chemical control systems.

A case report of progressive obstruction of Ex-PRESS miniature glaucoma shunt after transient flat anterior chamber and treatment using Nd:YAG laser.

PubMed

Tanito, Masaki; Sano, Ichiya; Ohira, Akihiro

2015-01-08

We report a case of Ex-PRESS miniature glaucoma shunt obstruction resulting from progressive iris synechial formation after transient anterior chamber shallowing. A 68-year-old woman with pseudoexfoliation glaucoma in her right eye underwent filtration surgery with implantation of the Ex-PPESS shunt (model P-50, Alcon Japan, Tokyo, Japan) in combination with intra-surgical 0.04% mitomycin C use. After the anterior chamber injection of viscoelastic material and 100% sulfur hexafluoride gas for treatment of early postoperative over filtration, the intraocular pressure (IOP) was controlled between 9 and 12 mmHg. On postoperative day 121, gonioscopy showed that synechial formation around the shunt obstructed the axial port leaving the relief port opened. On postoperative day 274, the intraocular pressure increased to 40 mmHg and synechiae obstructed both the axial and relief ports. Dispersion of iris tissue by neodymium:yttrium-aluminium-garnet (Nd:YAG) laser (2 mJ, one shot to each port) opened both ports and immediately lowered the IOP, leaving peripheral anterior synechiae around the shunt. Up to postoperative day 400, the IOP was controlled between 13 and 15 mmHg, and the cystic bleb was maintained. The synechiae formed gradually extends around the shunt's shaft and can result in later external obstruction of the relief port. The current case requires further follow-up since synechiae remaining around the shaft can cause future obstruction. We emphasize the fact that, if the iris synechiae to the shunt once formed, it can progress and obstruct the shunt ports later.

The challenge of developing structural materials for fusion power systems

NASA Astrophysics Data System (ADS)

Bloom, Everett E.

1998-10-01

Nuclear fusion can be one of the most attractive sources of energy from the viewpoint of safety and minimal environmental impact. Central in the goal of designing a safe, environmentally benign, and economically competitive fusion power system is the requirement for high performance, low activation materials. The general performance requirements for such materials have been defined and it is clear that materials developed for other applications (e.g. aerospace, nuclear fission, fossil energy systems) will not fully meet the needs of fusion. Advanced materials, with composition and microstructure tailored to yield properties that will satisfy the specific requirements of fusion must be developed. The international fusion programs have made significant progress towards this goal. Compositional requirements for low activation lead to a focus of development efforts on silicon carbide composites, vanadium alloys, and advanced martensitic steels as candidate structural material systems. Control of impurities will be critically important in actually achieving low activation but this appears possible. Neutron irradiation produces significant changes in the mechanical and physical properties of each of these material systems raising feasibility questions and design limitations. A focus of the research and development effort is to understand these effects, and through the development of specific compositions and microstructures, produce materials with improved and adequate performance. Other areas of research that are synergistic with the development of radiation resistant materials include fabrication, joining technology, chemical compatibility with coolants and tritium breeders and specific questions relating to the unique characteristics of a given material (e.g. coatings to reduce gas permeation in SiC composites) or design concept (e.g. electrical insulator coatings for liquid metal concepts).

Energy Absorption in Chopped Carbon Fiber Compression Molded Composites

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

Starbuck, J.M.

2001-07-20

In passenger vehicles the ability to absorb energy due to impact and be survivable for the occupant is called the ''crashworthiness'' of the structure. To identify and quantify the energy absorbing mechanisms in candidate automotive composite materials, test methodologies were developed for conducting progressive crush tests on composite plate specimens. The test method development and experimental set-up focused on isolating the damage modes associated with the frond formation that occurs in dynamic testing of composite tubes. Quasi-static progressive crush tests were performed on composite plates manufactured from chopped carbon fiber with an epoxy resin system using compression molding techniques. Themore » carbon fiber was Toray T700 and the epoxy resin was YLA RS-35. The effect of various material and test parameters on energy absorption was evaluated by varying the following parameters during testing: fiber volume fraction, fiber length, fiber tow size, specimen width, profile radius, and profile constraint condition. It was demonstrated during testing that the use of a roller constraint directed the crushing process and the load deflection curves were similar to progressive crushing of tubes. Of all the parameters evaluated, the fiber length appeared to be the most critical material parameter, with shorter fibers having a higher specific energy absorption than longer fibers. The combination of material parameters that yielded the highest energy absorbing material was identified.« less

Overview of NASA's Thermal Control System Development for Exploration Project

NASA Technical Reports Server (NTRS)

Stephan, Ryan A.

2011-01-01

The now-cancelled Constellation Program included the Orion, Altair, and Lunar Surface Systems project offices. The first two elements, Orion and Altair, were planned to be manned space vehicles while the third element was much more diverse and included several sub-elements. Among other things, these sub-elements were Rovers and a Lunar Habitat. The planned missions involving these systems and vehicles included several risks and design challenges. Due to the unique thermal operating environment, many of these risks and challenges were associated with the vehicles thermal control system. NASA s Exploration Technology Development Program (ETDP) consisted of various technology development projects. The project chartered with mitigating the aforementioned thermal risks and design challenges was the Thermal Control System Development for Exploration Project. These risks and design challenges were being addressed through a rigorous technology development process that was planned to culminate with an integrated thermal control system test. Although the technologies being developed were originally aimed towards mitigating specific Constellation risks, the technology development process is being continued within a new program. This continued effort is justified by the fact that many of the technologies are generically applicable to future spacecraft thermal control systems. The current paper summarizes the development efforts being performed by the technology development project. The development efforts involve heat acquisition and heat rejection hardware including radiators, heat exchangers, and evaporators. The project has also been developing advanced phase change material heat sinks and performing a material compatibility assessment for a promising thermal control system working fluid. The to-date progress and lessons-learned from these development efforts will be discussed throughout the paper.

RESEARCH AND DEVELOPMENT ON ADVANCED GRAPHITE MATERIALS. Final Report

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

None

1962-04-01

A review is given of activities over the period October 15, 1960 to October 15, 1961 on a three year program for the research and development of materials, experimental techniques, and equipment for development of premium quality, reproducible graphite-base materials suitable for missile and astronautic applications. Progress is reported on research and development in the study areas of raw materials, fabrication, and material characterization and evaluation. (auth)

FY2010 Annual Progress Report for Propulsion Materials

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

Davis, Patrick B.; Schutte, Carol L.; Gibbs, Jerry L.

The Propulsion Materials Technology actively supports the energy security and reduction of greenhouse emissions goals of the Vehicle Technologies Program by developing advanced materials that enable development of higher efficiency powertrains for ground transportation. Propulsion Materials works closely with the other disciplines within the VT Program to identify the materials properties essential for the development of cost-effective, highly efficient, and environmentally friendly next-generation heavy and light duty powertrains.

14 CFR 1274.701 - Suspension or termination.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Agreement if the recipient is not making anticipated technical progress, if the recipient materially changes...) Similarly, the recipient may terminate the agreement if, for example, technical progress is not being made, if the commercial recipient shifts its technical emphasis, or if other technological advances have...

14 CFR 1274.701 - Suspension or termination.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Agreement if the recipient is not making anticipated technical progress, if the recipient materially changes...) Similarly, the recipient may terminate the agreement if, for example, technical progress is not being made, if the commercial recipient shifts its technical emphasis, or if other technological advances have...

23 CFR 635.122 - Participation in progress payments.

Code of Federal Regulations, 2010 CFR

2010-04-01

... OPERATIONS CONSTRUCTION AND MAINTENANCE Contract Procedures § 635.122 Participation in progress payments. (a..., based on a request for reimbursement submitted by State transportation departments. When the contract... value of the stockpiled material shall not exceed the appropriate portion of the value of the contract...

An approach to achieve progress in spacecraft shielding

NASA Astrophysics Data System (ADS)

Thoma, K.; Schäfer, F.; Hiermaier, S.; Schneider, E.

2004-01-01

Progress in shield design against space debris can be achieved only when a combined approach based on several tools is used. This approach depends on the combined application of advanced numerical methods, specific material models and experimental determination of input parameters for these models. Examples of experimental methods for material characterization are given, covering the range from quasi static to very high strain rates for materials like Nextel and carbon fiber-reinforced materials. Mesh free numerical methods have extraordinary capabilities in the simulation of extreme material behaviour including complete failure with phase changes, combined with shock wave phenomena and the interaction with structural components. In this paper the benefits from combining numerical methods, material modelling and detailed experimental studies for shield design are demonstrated. The following examples are given: (1) Development of a material model for Nextel and Kevlar-Epoxy to enable numerical simulation of hypervelocity impacts on complex heavy protection shields for the International Space Station. (2) The influence of projectile shape on protection performance of Whipple Shields and how experimental problems in accelerating such shapes can be overcome by systematic numerical simulation. (3) The benefits of using metallic foams in "sandwich bumper shields" for spacecraft and how to approach systematic characterization of such materials.

Modeling Geometry and Progressive Failure of Material Interfaces in Plain Weave Composites

NASA Technical Reports Server (NTRS)

Hsu, Su-Yuen; Cheng, Ron-Bin

2010-01-01

A procedure combining a geometrically nonlinear, explicit-dynamics contact analysis, computer aided design techniques, and elasticity-based mesh adjustment is proposed to efficiently generate realistic finite element models for meso-mechanical analysis of progressive failure in textile composites. In the procedure, the geometry of fiber tows is obtained by imposing a fictitious expansion on the tows. Meshes resulting from the procedure are conformal with the computed tow-tow and tow-matrix interfaces but are incongruent at the interfaces. The mesh interfaces are treated as cohesive contact surfaces not only to resolve the incongruence but also to simulate progressive failure. The method is employed to simulate debonding at the material interfaces in a ceramic-matrix plain weave composite with matrix porosity and in a polymeric matrix plain weave composite without matrix porosity, both subject to uniaxial cyclic loading. The numerical results indicate progression of the interfacial damage during every loading and reverse loading event in a constant strain amplitude cyclic process. However, the composites show different patterns of damage advancement.

Thin-film thermoelectric devices with high room-temperature figures of merit.

PubMed

Venkatasubramanian, R; Siivola, E; Colpitts, T; O'Quinn, B

2001-10-11

Thermoelectric materials are of interest for applications as heat pumps and power generators. The performance of thermoelectric devices is quantified by a figure of merit, ZT, where Z is a measure of a material's thermoelectric properties and T is the absolute temperature. A material with a figure of merit of around unity was first reported over four decades ago, but since then-despite investigation of various approaches-there has been only modest progress in finding materials with enhanced ZT values at room temperature. Here we report thin-film thermoelectric materials that demonstrate a significant enhancement in ZT at 300 K, compared to state-of-the-art bulk Bi2Te3 alloys. This amounts to a maximum observed factor of approximately 2.4 for our p-type Bi2Te3/Sb2Te3 superlattice devices. The enhancement is achieved by controlling the transport of phonons and electrons in the superlattices. Preliminary devices exhibit significant cooling (32 K at around room temperature) and the potential to pump a heat flux of up to 700 W cm-2; the localized cooling and heating occurs some 23,000 times faster than in bulk devices. We anticipate that the combination of performance, power density and speed achieved in these materials will lead to diverse technological applications: for example, in thermochemistry-on-a-chip, DNA microarrays, fibre-optic switches and microelectrothermal systems.

Drug Release Kinetics and Transport Mechanisms of Non-degradable and Degradable Polymeric Delivery Systems

PubMed Central

Fu, Yao; Kao, Weiyuan John

2010-01-01

Importance of the field The advancement in material design and engineering has led to the rapid development of novel materials with increasing complexity and functions. Both non-degradable and degradable polymers have found wide applications in the controlled delivery field. Studies on drug release kinetics provide important information into the function of material systems. To elucidate the detailed transport mechanism and the structure-function relationship of a material system, it is critical to bridge the gap between the macroscopic data and the transport behavior at the molecular level. Areas covered in this review The structure and function information of selected non-degradable and degradable polymers have been collected and summarized from literatures published after 1990s. The release kinetics of selected drug compounds from various material systems will be discussed in case studies. Recent progresses in the mathematical models based on different transport mechanisms will be highlighted. What the reader will gain This article aims to provide an overview of structure-function relationships of selected non-degradable and degradable polymers as drug delivery matrices. Take home message Understanding the structure-function relationship of the material system is key to the successful design of a delivery system for a particular application. Moreover, developing complex polymeric matrices requires more robust mathematical models to elucidate the solute transport mechanisms. PMID:20331353

New Brunswick Laboratory. Progress report, October 1995--September 1996

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

NONE

Fiscal year (FY) 1996 was a very good year for New Brunswick Laboratory (NBL), whose major sponsor is the Office of Safeguards and Security (NN-51) in the US Department of Energy (DOE), Office of Nonproliferation and National Security, Office of Security Affairs. Several projects pertinent to the NBL mission were completed, and NBL`s interactions with partners and customers were encouraging. Among the partners with which NBL interacted in this report period were the International Atomic Energy Agency (IAEA), NN-51. Environmental Program Group of the DOE Chicago Operations Office, International Safeguards Project Office, Waste Isolation Pilot Plant (WIPP), Ukraine Working Group,more » Fissile Materials Assurance Working Group, National Institute of Standards and Technology (NIST), Nuclear Regulatory Commission (NRC), Institute for Reference Materials and Measurements (IRMM) in Belgium, Brazilian/Argentine Agency for Accounting and Control of Nuclear Materials (ABACC), Lockheed Idaho Technologies Company, and other DOE facilities and laboratories. NBL staff publications, participation in safeguards assistance and other nuclear programs, development of new reference materials, involvement in the updating and refinement of DOE documents, service in enhancing the science education of others, and other related activities enhanced NBL`s status among DOE laboratories and facilities. Noteworthy are the facts that NBL`s small inventory of nuclear materials is accurately accounted for, and, as in past years, its materials and human resources were used in peaceful nuclear activities worldwide.« less

Asymmetric Semiconductor Nanorod/Oxide Nanoparticle Hybrid Materials: Model Nanomaterials for Light-Activated Formation of Fuels from Sunlight. Formal Progress Report -- Award DE-FG02-05ER15753

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

Armstrong, Neal R.

Executive Summary on Project Accomplishments: We focused our efforts for this project on the synthesis and characterization of semiconductor nanomaterials composed of semiconductor nanorods (NRs - e.g., CdSe, CdSe@CdS, CdS) with metal (Au, Pt, Co) or metal oxide (CoxOy) nanoparticle (NP) “tips.” These systems are attractive model systems where control of spatial, energetic and compositional features of both NRs and NP tips potentially enhances the efficiency of photogeneration and directional transport of charges, and photoelectrochemical conversion of sunlight to fuels. Synthetic methods to control material dimensions (20-200 nm in length), topology (one vs. two NP tips) and NR/NP tip compositionsmore » have been developed in the current project period (Pyun). We also achieved, for the first time in heterostructured nanorod materials, estimates of both valence band energies (E VB) and conduction band energies (E CB), using unique combinations of in vacuuo ultraviolet photoelectron spectroscopy (UPS, Armstrong), and waveguide spectroelectrochemistry (Saavedra), respectively. The spectroelectrochemical measurements in particular provide a unique path to estimation of E CB, and the distribution in E CB brought about by modification of NR composition. The combination of both approaches promises to be universally applicable to the characterization of energetics in nanomaterials of interest both for photovoltaic and sunlight-to-fuel photoelectrochemical assemblies.« less

Investigation of criticality safety control infraction data at a nuclear facility

DOE PAGES

Cournoyer, Michael E.; Merhege, James F.; Costa, David A.; ...

2014-10-27

Chemical and metallurgical operations involving plutonium and other nuclear materials account for most activities performed at the LANL's Plutonium Facility (PF-4). The presence of large quantities of fissile materials in numerous forms at PF-4 makes it necessary to maintain an active criticality safety program. The LANL Nuclear Criticality Safety (NCS) Program provides guidance to enable efficient operations while ensuring prevention of criticality accidents in the handling, storing, processing and transportation of fissionable material at PF-4. In order to achieve and sustain lower criticality safety control infraction (CSCI) rates, PF-4 operations are continuously improved, through the use of Lean Manufacturing andmore » Six Sigma (LSS) business practices. Employing LSS, statistically significant variations (trends) can be identified in PF-4 CSCI reports. In this study, trends have been identified in the NCS Program using the NCS Database. An output metric has been developed that measures ADPSM Management progress toward meeting its NCS objectives and goals. Using a Pareto Chart, the primary CSCI attributes have been determined in order of those requiring the most management support. Data generated from analysis of CSCI data help identify and reduce number of corresponding attributes. In-field monitoring of CSCI's contribute to an organization's scientific and technological excellence by providing information that can be used to improve criticality safety operation safety. This increases technical knowledge and augments operational safety.« less

OA-7 Service Module Arrival

NASA Image and Video Library

2017-02-01

The Orbital ATK OA-7 Cygnus spacecraft's service module arrives inside the Space Station Processing Facility of NASA's Kennedy Space Center in Florida. The service module is sealed in an environmentally controlled shipping container, pulled in by truck on a low-boy flatbed trailer. Scheduled to launch on March 19, 2017, the Orbital ATK OA-7 mission will lift off atop a United Launch Alliance Atlas V rocket from Space launch Complex 41 at Cape Canaveral Air Force Station. The commercial resupply services mission to the International Space Station will deliver thousands of pounds of supplies, equipment and scientific research materials that improve life on Earth and drive progress toward future space exploration.

OA-7 Cargo Module Arrival

NASA Image and Video Library

2017-01-09

The Orbital ATK OA-7 Cygnus spacecraft's pressurized cargo module (PCM) arrives at the Space Station Processing Facility of NASA's Kennedy Space Center in Florida. The PCM is sealed in an environmentally controlled shipping container, pulled in by truck on a low-boy flatbed trailer. Scheduled to launch in March 2017, the Orbital ATK OA-7 mission will lift off atop a United Launch Alliance Atlas V rocket from Space launch Complex 41 at Cape Canaveral Air Force Station. The commercial resupply services mission to the International Space Station will deliver thousands of pounds of supplies, equipment and scientific research materials that improve life on Earth and drive progress toward future space exploration.

DNA-templated photonic arrays and assemblies: design principles and future opportunities.

PubMed

Su, Wu; Bonnard, Vanessa; Burley, Glenn A

2011-07-11

Molecular photonics is a rapidly developing and multi-disciplinary field of research involving the construction of molecular assemblies comprising photoactive building blocks that are responsive to a light stimulus. A salient challenge in this field is the controlled assembly of these building blocks with nanoscale precision. DNA exhibits considerable promise as an architecture for the templated assembly of photoactive materials. In this Concept Article we describe the progress that has been made in the area of DNA photonics, in which DNA acts as a platform for the construction of optoelectronic assemblies, thin films and devices. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tunable intraparticle frameworks for creating complex heterostructured nanoparticle libraries

NASA Astrophysics Data System (ADS)

Fenton, Julie L.; Steimle, Benjamin C.; Schaak, Raymond E.

2018-05-01

Complex heterostructured nanoparticles with precisely defined materials and interfaces are important for many applications. However, rationally incorporating such features into nanoparticles with rigorous morphology control remains a synthetic bottleneck. We define a modular divergent synthesis strategy that progressively transforms simple nanoparticle synthons into increasingly sophisticated products. We introduce a series of tunable interfaces into zero-, one-, and two-dimensional copper sulfide nanoparticles using cation exchange reactions. Subsequent manipulation of these intraparticle frameworks yielded a library of 47 distinct heterostructured metal sulfide derivatives, including particles that contain asymmetric, patchy, porous, and sculpted nanoarchitectures. This generalizable mix-and-match strategy provides predictable retrosynthetic pathways to complex nanoparticle features that are otherwise inaccessible.

OA-7 Cargo Module Move from Airlock to Highbay

NASA Image and Video Library

2017-01-10

Inside an environmentally controlled shipping container the Orbital ATK OA-7 Cygnus spacecraft's pressurized cargo module (PCM) moves from an airlock to the high bay of the Space Station Processing Facility of NASA's Kennedy Space Center in Florida. Scheduled to launch on March 19, 2017, the Orbital ATK OA-7 mission will lift off atop a United Launch Alliance Atlas V rocket from Space launch Complex 41 at Cape Canaveral Air Force Station. The commercial resupply services mission to the International Space Station will deliver thousands of pounds of supplies, equipment and scientific research materials that improve life on Earth and drive progress toward future space exploration.

OA-7 Cargo Module Move from Airlock to Highbay

NASA Image and Video Library

2017-01-10

The Orbital ATK OA-7 Cygnus spacecraft's pressurized cargo module (PCM) arrives at the Space Station Processing Facility of NASA's Kennedy Space Center in Florida. The PCM is sealed in an environmentally controlled shipping container. Scheduled to launch on March 19, 2017, the Orbital ATK OA-7 mission will lift off atop a United Launch Alliance Atlas V rocket from Space launch Complex 41 at Cape Canaveral Air Force Station. The commercial resupply services mission to the International Space Station will deliver thousands of pounds of supplies, equipment and scientific research materials that improve life on Earth and drive progress toward future space exploration.

Final Progress Report, Renewable and Logistics Fuels for Fuel Cells at the Colorado School of Mines

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

Sullivan, Neal P.

The objective of this program is to advance the current state of technology of solid-oxide fuel cells (SOFCs) to improve performance when operating on renewable and logistics hydrocarbon fuel streams. Outcomes will include: 1.) new SOFC materials and architectures that address the technical challenges associated with carbon-deposit formation and sulfur poisoning; 2.) new integration strategies for combining fuel reformers with SOFCs; 3.) advanced modeling tools that bridge the scales of fundamental charge-transfer chemistry to system operation and control; and 4.) outreach through creation of the Distinguished Lecturer Series to promote nationwide collaboration with fuel-cell researchers and scientists.

Recent Progress in Photocatalysis Mediated by Colloidal II-VI Nanocrystals

PubMed Central

Wilker, Molly B; Schnitzenbaumer, Kyle J; Dukovic, Gordana

2012-01-01

The use of photoexcited electrons and holes in semiconductor nanocrystals as reduction and oxidation reagents is an intriguing way of harvesting photon energy to drive chemical reactions. This review focuses on recent research efforts to understand and control the photocatalytic processes mediated by colloidal II-VI nanocrystalline materials, such as cadmium and zinc chalcogenides. First, we highlight how nanocrystal properties govern the rates and efficiencies of charge-transfer processes relevant to photocatalysis. We then describe the use of nanocrystal catalyst heterostructures for fuel-forming reactions, most commonly H2 generation. Finally, we review the use of nanocrystal photocatalysis as a synthetic tool for metal–semiconductor nano-heterostructures. PMID:24115781

Wire electric-discharge machining and other fabrication techniques

NASA Technical Reports Server (NTRS)

Morgan, W. H.

1983-01-01

Wire electric discharge machining and extrude honing were used to fabricate a two dimensional wing for cryogenic wind tunnel testing. Electric-discharge cutting is done with a moving wire electrode. The cut track is controlled by means of a punched-tape program and the cutting feed is regulated according to the progress of the work. Electric-discharge machining involves no contact with the work piece, and no mechanical force is exerted. Extrude hone is a process for honing finish-machined surfaces by the extrusion of an abrasive material (silly putty), which is forced through a restrictive fixture. The fabrication steps are described and production times are given.

Influence of electrospun fiber mesh size on hMSC oxygen metabolism in 3D collagen matrices: experimental and theoretical evidences.

PubMed

Guaccio, Angela; Guarino, Vincenzo; Perez, Marco A Alvarez-; Cirillo, Valentina; Netti, Paolo A; Ambrosio, Luigi

2011-08-01

The traditional paradigm of tissue engineering of regenerating in vitro tissue or organs, through the combination of an artificial matrix and a cellular population has progressively changed direction. The most recent concept is the realization of a fully functional biohybrid, where both, the artificial and the biotic phase, concur in the formation of the novel organic matter. In this direction, interest is growing in approaches taking advantage of the control at micro- and nano-scale of cell material interaction based on the realization of elementary tassels of cells and materials which constitute the beginning point for the expansion of 3D more complex structures. Since a spontaneous assembly of all these components is expected, however, it becomes more fundamental than ever to define the features influencing cellular behavior, either they were material functional properties, or material architecture. In this work, it has been investigated the direct effect of electrospun fiber sizes on oxygen metabolism of h-MSC cells, when any other culture parameter was kept constant. To this aim, thin PCL electrospun membranes, with micro- and nano-scale texturing, were layered between two collagen slices up to create a sandwich structure (µC-PCL-C and nC-PCL-C). Cells were seeded on membranes, and the oxygen consumption was determined by a phosphorescence quenching technique. Results indicate a strong effect of the architecture of scaffolds on cell metabolism, also revealed by the increasing of HIF1-α gene expression in nC-PCL-C. These findings offer new insights into the role of materials in specific cell activities, also implying the existence of very interesting criteria for the control of tissue growth through the tuning of scaffold architecture. Copyright © 2011 Wiley Periodicals, Inc.

Impact of growth rate on graphene lattice-defect formation within a single crystalline domain.

PubMed

Chin, Hao-Ting; Lee, Jian-Jhang; Hofmann, Mario; Hsieh, Ya-Ping

2018-03-06

Chemical vapor deposition (CVD) is promising for the large scale production of graphene and other two-dimensional materials. Optimization of the CVD process for enhancing their quality is a focus of ongoing effort and significant progress has been made in decreasing the defectiveness associated with grain boundaries and nucleation spots. However, little is known about the quality and origin of structural defects in the outgrowing lattice which are present even in single-crystalline material and represent the limit of current optimization efforts. We here investigate the formation kinetics of such defects by controlling graphene's growth rate over a wide range using nanoscale confinements. Statistical analysis of Raman spectroscopic results shows a clear trend between growth rate and defectiveness that is in quantitative agreement with a model where defects are healed preferentially at the growth front. Our results suggest that low growth rates are required to avoid the freezing of lattice defects and form high quality material. This conclusion is confirmed by a fourfold enhancement in graphene's carrier mobility upon optimization of the growth rate.

Synthesis of hybrid cellulose nanocomposite bonded with dopamine SiO2/TiO2 and its antimicrobial activity

NASA Astrophysics Data System (ADS)

Ramesh, Sivalingam; Kim, Gwang-Hoon; Kim, Jaehwan; Kim, Joo-Hyung

2015-04-01

Organic-inorganic hybrid material based cellulose was synthesized by the sol-gel approach. The explosion of activity in this area in the past decade has made tremendous progress in industry or academic both fundamental understanding of sol-gel process and applications of new functionalized hybrid materials. In this present research work, we focused on cellulose-dopamine functionalized SiO2/TiO2 hybrid nanocomposite by sol-gel process. The cellulose-dopamine hybrid nanocomposite was synthesized via γ-aminopropyltriethoxysilane (γ-APTES) coupling agent by in-situ sol-gel process. The chemical structure of cellulose-amine functionalized dopamine bonding to cellulose structure with covalent cross linking hybrids was confirmed by FTIR spectral analysis. The morphological analysis of cellulose-dopamine nanoSiO2/TiO2 hybrid nanocomposite materials was characterized by XRD, SEM and TEM. From this different analysis results indicate that the optical transparency, thermal stability, control morphology of cellulose-dopamine-SiO2/TiO2 hybrid nanocomposite. Furthermore cellulose-dopamine-SiO2/TiO2 hybrid nanocomposite was tested against pathogenic bacteria for antimicrobial activity.

Fluorescence-based bioassays for the detection and evaluation of food materials.

PubMed

Nishi, Kentaro; Isobe, Shin-Ichiro; Zhu, Yun; Kiyama, Ryoiti

2015-10-13

We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based microarrays/biochips, such as antibody/protein microarrays, bead/suspension arrays, capillary/sensor arrays, DNA microarrays/polymerase chain reaction (PCR)-based arrays, glycan/lectin arrays, immunoassay/enzyme-linked immunosorbent assay (ELISA)-based arrays, microfluidic chips and tissue arrays, have been developed and used for the assessment of allergy/poisoning/toxicity, contamination and efficacy/mechanism, and quality control/safety. DNA microarray assays have been used widely for food safety and quality as well as searches for active components. DNA microarray-based gene expression profiling may be useful for such purposes due to its advantages in the evaluation of pathway-based intracellular signaling in response to food materials.

Fluorescence-Based Bioassays for the Detection and Evaluation of Food Materials

PubMed Central

Nishi, Kentaro; Isobe, Shin-Ichiro; Zhu, Yun; Kiyama, Ryoiti

2015-01-01

We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based microarrays/biochips, such as antibody/protein microarrays, bead/suspension arrays, capillary/sensor arrays, DNA microarrays/polymerase chain reaction (PCR)-based arrays, glycan/lectin arrays, immunoassay/enzyme-linked immunosorbent assay (ELISA)-based arrays, microfluidic chips and tissue arrays, have been developed and used for the assessment of allergy/poisoning/toxicity, contamination and efficacy/mechanism, and quality control/safety. DNA microarray assays have been used widely for food safety and quality as well as searches for active components. DNA microarray-based gene expression profiling may be useful for such purposes due to its advantages in the evaluation of pathway-based intracellular signaling in response to food materials. PMID:26473869

Lithium Iron Orthosilicate Cathode: Progress and Perspectives

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

Ni, Jiangfeng; Jiang, Yu; Bi, Xuanxuan

2017-07-18

The pursuit of cathodes with a high capacity is remarkably driven by the ever increasing demand of high-energy lithium ion batteries in electronics and transportation. In this regard, polyanionic lithium iron orthosilicate (Li2FeSiO4) offers a promising opportunity because it affords a high theoretical capacity of 331 mAh g–1. However, such a high theoretical capacity of Li2FeSiO4 has frequently been compromised in practice because of the extremely low electronic and ionic conductivity. To address this issue, material engineering strategies to boost the Li storage kinetics in Li2FeSiO4 have proven indispensable. In this Perspective, we will briefly present the structural characteristics, intrinsicmore » physicochemical properties, and electrochemical behavior of Li2FeSiO4. We particularly focus on recent materials engineering of silicates, which is implemented mainly through advanced synthetic techniques and elaborate controls. This Perspective highlights the importance of integrating theoretical analysis into experimental implementation to further advance the Li2FeSiO4 materials.« less

Ordered materials for organic electronics and photonics.

PubMed

O'Neill, Mary; Kelly, Stephen M

2011-02-01

We present a critical review of semiconducting/light emitting, liquid crystalline materials and their use in electronic and photonic devices such as transistors, photovoltaics, OLEDs and lasers. We report that annealing from the mesophase improves the order and packing of organic semiconductors to produce state-of-the-art transistors. We discuss theoretical models which predict how charge transport and light emission is affected by the liquid crystalline phase. Organic photovoltaics and OLEDs require optimization of both charge transport and optical properties and we identify the various trade-offs involved for ordered materials. We report the crosslinking of reactive mesogens to give pixellated full-colour OLEDs and distributed bi-layer photovoltaics. We show how the molecular organization inherent to the mesophase can control the polarization of light-emitting devices and the gain in organic, thin-film lasers and can also provide distributed feedback in chiral nematic mirrorless lasers. We update progress on the surface alignment of liquid crystalline semiconductors to obtain monodomain devices without defects or devices with spatially varying properties. Finally the significance of all of these developments is assessed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radiation Therapy to the Primary and Postinduction Chemotherapy MIBG-Avid Sites in High-Risk Neuroblastoma

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

Mazloom, Ali; Louis, Chrystal U.; Nuchtern, Jed

2014-11-15

Purpose: Although it is generally accepted that consolidation therapy for neuroblastoma includes irradiation of the primary site and any remaining metaiodobenzylguanidine (MIBG)-avid metastatic sites, limited information has been published regarding the efficacy of this approach. Methods and Materials: Thirty patients with high-risk neuroblastoma were treated at 1 radiation therapy (RT) department after receiving 5 cycles of induction chemotherapy and resection. All patients had at least a partial response after induction therapy, based upon international neuroblastoma response criteria. The primary sites were treated with 24 to 30 Gy whereas the MIBG-avid metastatic sites were treated with 24 Gy. RT was followed by high-dosemore » chemotherapy with autologous stem cell rescue and 6 months of cis-retinoic acid. Results: The 5-year progression-free survival (PFS) and overall survival (OS) rates were 48% and 59%, respectively. The 5-year locoregional control at the primary site was 84%. There were no differences in locoregional control according to degree of primary surgical resection. The 5-year local control rate for metastatic sites was 74%. The 5-year PFS rates for patients with 0, 1, 2, and >3 postinduction MIBG sites were 66%, 57%, 20%, and 0% (P<.0001), respectively, whereas 5-year OS rates were 80%, 57%, 50%, and 0%, respectively (P<.0001). Conclusions: RT to the primary site and postinduction MIBG-positive metastatic sites was associated with 84% and 74% local control, respectively. The number of MIBG-avid sites present after induction chemotherapy and surgery was predictive of progression-free and overall survival.« less

Role of 4- tert -Butylpyridine as a Hole Transport Layer Morphological Controller in Perovskite Solar Cells

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

Wang, Shen; Sina, Mahsa; Parikh, Pritesh

2016-09-14

Hybrid organic-inorganic materials for high efficiency, low cost photovoltaic devices have seen rapid progress since the introduction of lead based perovskites and solid-state hole transport layers. Although majority of the materials used for perovskite solar cells (PSC) are introduced from dye-sensitized solar cells (DSSCs), the presence of a perovskite capping layer as opposed to a single dye molecule (in DSSCs) changes the interactions between the various layers in perovskite solar cells. 4-tert-butylpyridine (tBP), commonly used in PSCs, is assumed to function as a charge recombination inhibitor, similar to DSSCs. However, the presence of a perovskite capping layer calls for amore » re-evaluation of its function in PSCs. Using TEM (transmission electron microscopy), we first confirm the role of tBP as a HTL morphology controller in PSCs. Our observations suggest that tBP significantly improves the uniformity of the HTL and avoids accumulation of Li salt. We also study degradation pathways by using FTIR (Fourier transform infrared spectroscopy) and APT (atom probe tomography) to investigate and visualize in 3-dimensions the moisture content associated with the Li salt. Long term effects, over 1000 hours, due to evaporation of tBP have also been studied. Based on our findings, a PSC failure mechanism associated with the morphological change of the HTL is proposed. tBP, the morphology controller in HTL, plays a key role in this process and thus this study highlights the need for additive materials with higher boiling points for consistent long term performance of PSCs.« less

Role of 4-tert-Butylpyridine as a Hole Transport Layer Morphological Controller in Perovskite Solar Cells.

PubMed

Wang, Shen; Sina, Mahsa; Parikh, Pritesh; Uekert, Taylor; Shahbazian, Brian; Devaraj, Arun; Meng, Ying Shirley

2016-09-14

Hybrid organic-inorganic materials for high-efficiency, low-cost photovoltaic devices have seen rapid progress since the introduction of lead based perovskites and solid-state hole transport layers. Although majority of the materials used for perovskite solar cells (PSC) are introduced from dye-sensitized solar cells (DSSCs), the presence of a perovskite capping layer as opposed to a single dye molecule (in DSSCs) changes the interactions between the various layers in perovskite solar cells. 4-tert-Butylpyridine (tBP), commonly used in PSCs, is assumed to function as a charge recombination inhibitor, similar to DSSCs. However, the presence of a perovskite capping layer calls for a re-evaluation of its function in PSCs. Using TEM (transmission electron microscopy), we first confirm the role of tBP as a HTL morphology controller in PSCs. Our observations suggest that tBP significantly improves the uniformity of the HTL and avoids accumulation of Li salt. We also study degradation pathways by using FTIR (Fourier transform infrared spectroscopy) and APT (atom probe tomography) to investigate and visualize in 3-dimensions the moisture content associated with the Li salt. Long-term effects, over 1000 h, due to evaporation of tBP have also been studied. Based on our findings, a PSC failure mechanism associated with the morphological change of the HTL is proposed. tBP, the morphology controller in HTL, plays a key role in this process, and thus this study highlights the need for additive materials with higher boiling points for consistent long-term performance of PSCs.

Studies in nonlinear problems of energy. Progress report, October 1, 1993--September 30, 1994

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

Matkowsky, B.J.

1994-09-01

The authors concentrate on modeling, analysis and large scale scientific computation of combustion and flame propagation phenomena, with emphasis on the transition from laminar to turbulent combustion. In the transition process a flame passed through a stages exhibiting increasingly complex spatial and temporal patterns which serve as signatures identifying each stage. Often the transitions arise via bifurcation. The authors investigate nonlinear dynamics, bifurcation and pattern formation in the successive stage of transition. They describe the stability of combustion waves, and transitions to combustion waves exhibiting progressively higher degrees of spatio-temporal complexity. One aspect of this research program is the systematicmore » derivation of appropriate, approximate models from the original models governing combustion. The approximate models are then analyzed. The authors are particularly interested in understanding the basic mechanisms affecting combustion, which is a prerequisite to effective control of the process. They are interested in determining the effects of varying various control parameters, such as Nusselt number, Lewis number, heat release, activation energy, Damkohler number, Reynolds number, Prandtl number, Peclet number, etc. The authors have also considered a number of problems in self-propagating high-temperature synthesis (SHS), in which combustion waves are employed to synthesize advanced materials. Efforts are directed toward understanding fundamental mechanisms. 167 refs.« less

Investigation of thermal fatigue in fiber composite materials. [(thermal cycling tests)

NASA Technical Reports Server (NTRS)

Fahmy, A. A.; Cunningham, T. G.

1976-01-01

Graphite-epoxy laminates were thermally cycled to determine the effects of thermal cycles on tensile properties and thermal expansion coefficients of the laminates. Three 12-ply laminate configurations were subjected to up to 5,000 thermal cycles. The cumulative effect of the thermal cycles was determined by destructive inspection (electron micrographs and tensile tests) of samples after progressively larger numbers of cycles. After thermal cycling, the materials' tensile strengths, moduli, and thermal expansion coefficients were significantly lower than for the materials as fabricated. Most of the degradation of properties occurred after only a few cycles. The property degradation was attributed primarily to the progressive development of matrix cracks whose locations depended upon the layup orientation of the laminate.

Current Challenges for HTCMC Aero-Propulsion Components

NASA Technical Reports Server (NTRS)

DiCarlo, James A.; Bansal, Narottam P.

2007-01-01

In comparison to the best metallic materials, HTCMC aero-propulsion engine components offer the opportunity of reduced weight and higher temperature operation, with corresponding improvements in engine cooling requirements, emissions, thrust, and specific fuel consumption. Although much progress has been made in the development of advanced HTCMC constituent materials and processes, major challenges still remain for their implementation into these components. The objectives of this presentation are to briefly review (1) potential HTCMC aero-propulsion components and their generic material performance requirements, (2) recent progress at NASA and elsewhere concerning advanced constituents and processes for meeting these requirements, (3) key HTCMC component implementation challenges that are currently being encountered, and (4) on-going activities within the new NASA Fundamental Aeronautics Program that are addressing these challenges.

Ultrasonographic Evaluation of Oral Submucous Fibrosis and Masseteric Hypertrophy

PubMed Central

Devathambi, Jones Raja; Aswath, Nalini

2013-01-01

Objectives: To evaluate the efficacy of ultrasonography (USG) as a non-invasive tool in assessing the severity of oral submucous fibrosis (OSMF) and also to assess the relationship between OSMF and hypertrophy of the masseter muscle. Materials and Methods: The submucosal thickness in buccal mucosa and masseteric muscle hypertrophy were measured using ultrasound (10-15 MHz) in 60 patients comprising 30 OSMF patients and 30 controls. Results: Results were analyzed by one way analysis of variance, Chi-square test and t-test. As the stages of OSMF advanced there was an increase in submucosal thickness of the buccal mucosa as well as masseter muscle thickness in both relaxed and contracted state in the study group when compared with controls (P < 0.005). Conclusion: USG is an effective non-invasive zero radiation tool for assessing the progression of OSMF. PMID:24516775

Differential quadrature method of nonlinear bending of functionally graded beam

NASA Astrophysics Data System (ADS)

Gangnian, Xu; Liansheng, Ma; Wang, Youzhi; Quan, Yuan; Weijie, You

2018-02-01

Using the third-order shear deflection beam theory (TBT), nonlinear bending of functionally graded (FG) beams composed with various amounts of ceramic and metal is analyzed utilizing the differential quadrature method (DQM). The properties of beam material are supposed to accord with the power law index along to thickness. First, according to the principle of stationary potential energy, the partial differential control formulae of the FG beams subjected to a distributed lateral force are derived. To obtain numerical results of the nonlinear bending, non-dimensional boundary conditions and control formulae are dispersed by applying the DQM. To verify the present solution, several examples are analyzed for nonlinear bending of homogeneous beams with various edges. A minute parametric research is in progress about the effect of the law index, transverse shear deformation, distributed lateral force and boundary conditions.

Non-contact profilometry of eroded and abraded enamel irradiated with an Er:YAG laser

PubMed Central

Scatolin, Renata Siqueira; Colucci, Vivian; Lepri, Taísa Penazzo; de Alexandria, Adílis Kalina; Maia, Lucianne Cople; Galo, Rodrigo; Borsatto, Maria Cristina; Corona, Silmara Aparecida Milori

2018-01-01

Abstract Literature has reported positive results regarding the use of lasers in the control of erosive lesions; however, evaluating whether they are effective in the control of the progression of erosive/abrasive lesions is important. Objectives This study aimed to evaluate the effect of the Er:YAG laser irradiation in controlling the progression of erosion associated with abrasive lesions in enamel. Material and methods Bovine incisors were sectioned, flattened and polished. Forty-eight enamel slabs were subjected to treatment in an intraoral phase. Twelve volunteers used an intraoral appliance containing one slab that was irradiated with an Er:YAG laser (5.2 J/cm2, 85 mJ, 2 Hz) and another non-irradiated slab on each side of the appliance, during one phase of 5 d, under a split-mouth design. Devices were subjected to erosive challenges (1% citric acid, 5 min, 3 times a day) and abrasive challenges one h after (brushing force of 1.5 N for 15 s) randomly and independently on each side of the device. Measurements of enamel loss were performed via 3D optical profilometry (μm). We analyzed data using the Kruskal-Wallis and Mann-Whitney tests and morphological characteristics via scanning electron microscopy. Results Following erosive and abrasive challenges, the group that was irradiated with the Er:YAG laser presented less loss of structure than the non-irradiated group. The group that underwent erosion and irradiation did not exhibit a significant difference from the non-irradiated group. Conclusion Irradiation with the Er:YAG laser did not control the loss of structure of enamel subjected to erosion but did control abrasion after erosion. PMID:29742259

Non-contact profilometry of eroded and abraded enamel irradiated with an Er:YAG laser.

PubMed

Scatolin, Renata Siqueira; Colucci, Vivian; Lepri, Taísa Penazzo; Alexandria, Adílis Kalina de; Maia, Lucianne Cople; Galo, Rodrigo; Borsatto, Maria Cristina; Corona, Silmara Aparecida Milori

2018-01-01

Literature has reported positive results regarding the use of lasers in the control of erosive lesions; however, evaluating whether they are effective in the control of the progression of erosive/abrasive lesions is important. Objectives This study aimed to evaluate the effect of the Er:YAG laser irradiation in controlling the progression of erosion associated with abrasive lesions in enamel. Material and methods Bovine incisors were sectioned, flattened and polished. Forty-eight enamel slabs were subjected to treatment in an intraoral phase. Twelve volunteers used an intraoral appliance containing one slab that was irradiated with an Er:YAG laser (5.2 J/cm2, 85 mJ, 2 Hz) and another non-irradiated slab on each side of the appliance, during one phase of 5 d, under a split-mouth design. Devices were subjected to erosive challenges (1% citric acid, 5 min, 3 times a day) and abrasive challenges one h after (brushing force of 1.5 N for 15 s) randomly and independently on each side of the device. Measurements of enamel loss were performed via 3D optical profilometry (μm). We analyzed data using the Kruskal-Wallis and Mann-Whitney tests and morphological characteristics via scanning electron microscopy. Results Following erosive and abrasive challenges, the group that was irradiated with the Er:YAG laser presented less loss of structure than the non-irradiated group. The group that underwent erosion and irradiation did not exhibit a significant difference from the non-irradiated group. Conclusion Irradiation with the Er:YAG laser did not control the loss of structure of enamel subjected to erosion but did control abrasion after erosion.

40 CFR 52.426 - Control strategy plans for attainment and rate-of-progress: ozone.

Code of Federal Regulations, 2010 CFR

2010-07-01

... and rate-of-progress: ozone. 52.426 Section 52.426 Protection of Environment ENVIRONMENTAL PROTECTION... § 52.426 Control strategy plans for attainment and rate-of-progress: ozone. (a) EPA fully approves, as... Delaware portion of the Philadelphia-Wilmington-Trenton severe ozone nonattainment, namely Kent and New...

40 CFR 52.1076 - Control strategy plans for attainment and rate-of-progress: Ozone.

Code of Federal Regulations, 2013 CFR

2013-07-01

... and rate-of-progress: Ozone. 52.1076 Section 52.1076 Protection of Environment ENVIRONMENTAL... (CONTINUED) Maryland § 52.1076 Control strategy plans for attainment and rate-of-progress: Ozone. (a) EPA is... associated contingency measures for the Cecil County ozone nonattainment area, submitted by the Secretary of...

40 CFR 52.1076 - Control strategy plans for attainment and rate-of-progress: Ozone.

Code of Federal Regulations, 2011 CFR

2011-07-01

... and rate-of-progress: Ozone. 52.1076 Section 52.1076 Protection of Environment ENVIRONMENTAL... (CONTINUED) Maryland § 52.1076 Control strategy plans for attainment and rate-of-progress: Ozone. (a) EPA is... associated contingency measures for the Cecil County ozone nonattainment area, submitted by the Secretary of...

40 CFR 52.426 - Control strategy plans for attainment and rate-of-progress: ozone.

Code of Federal Regulations, 2014 CFR

2014-07-01

... and rate-of-progress: ozone. 52.426 Section 52.426 Protection of Environment ENVIRONMENTAL PROTECTION... § 52.426 Control strategy plans for attainment and rate-of-progress: ozone. (a) EPA fully approves, as... Delaware portion of the Philadelphia-Wilmington-Trenton severe ozone nonattainment, namely Kent and New...

40 CFR 52.426 - Control strategy plans for attainment and rate-of-progress: ozone.

Code of Federal Regulations, 2011 CFR

2011-07-01

... and rate-of-progress: ozone. 52.426 Section 52.426 Protection of Environment ENVIRONMENTAL PROTECTION... § 52.426 Control strategy plans for attainment and rate-of-progress: ozone. (a) EPA fully approves, as... Delaware portion of the Philadelphia-Wilmington-Trenton severe ozone nonattainment, namely Kent and New...

40 CFR 52.426 - Control strategy plans for attainment and rate-of-progress: ozone.

Code of Federal Regulations, 2013 CFR

2013-07-01

... and rate-of-progress: ozone. 52.426 Section 52.426 Protection of Environment ENVIRONMENTAL PROTECTION... § 52.426 Control strategy plans for attainment and rate-of-progress: ozone. (a) EPA fully approves, as... Delaware portion of the Philadelphia-Wilmington-Trenton severe ozone nonattainment, namely Kent and New...

40 CFR 52.1076 - Control strategy plans for attainment and rate-of-progress: Ozone.

Code of Federal Regulations, 2014 CFR

2014-07-01

... and rate-of-progress: Ozone. 52.1076 Section 52.1076 Protection of Environment ENVIRONMENTAL... (CONTINUED) Maryland § 52.1076 Control strategy plans for attainment and rate-of-progress: Ozone. (a) EPA is... associated contingency measures for the Cecil County ozone nonattainment area, submitted by the Secretary of...

40 CFR 52.1076 - Control strategy plans for attainment and rate-of-progress: Ozone.

Code of Federal Regulations, 2012 CFR

2012-07-01

... and rate-of-progress: Ozone. 52.1076 Section 52.1076 Protection of Environment ENVIRONMENTAL... (CONTINUED) Maryland § 52.1076 Control strategy plans for attainment and rate-of-progress: Ozone. (a) EPA is... associated contingency measures for the Cecil County ozone nonattainment area, submitted by the Secretary of...

40 CFR 52.1076 - Control strategy plans for attainment and rate-of-progress: Ozone.

Code of Federal Regulations, 2010 CFR

2010-07-01

... and rate-of-progress: Ozone. 52.1076 Section 52.1076 Protection of Environment ENVIRONMENTAL... (CONTINUED) Maryland § 52.1076 Control strategy plans for attainment and rate-of-progress: Ozone. (a) EPA is... associated contingency measures for the Cecil County ozone nonattainment area, submitted by the Secretary of...