Synthesis and Accelerated Testing of Oxynitride Films for High Temperature Applications

NON-TECHNICAL DESCRIPTION:There is a critical need for new protective ceramic coatings that can operate in harsh environments with service temperatures in the 1000-1500oC range. These ceramic coatings must exhibit excellent heat resistance, chemical stability, fracture toughness and wear durability so they can be reliably be used in applications such high performance engines, shrouds, rotors, seals, slides, and bearings. A major problem is that conventional ceramic coatings crack and delaminate during thermal cycling in reactive gases at extreme temperatures. This project focuses on developing and testing Si-Al-O-N and Si-Zr-O-N thin film coatings and tailoring their properties to achieve high performance in terms of corrosion resistance, wear resistance, and fracture toughness. To efficiently test and evaluate the performance of the ceramic coatings in high temperature harsh environments, a microfabricated test platform is being developed, upon which the ceramic films are strategically deposited, to carry out accelerated testing under conditions that mimic those that are encountered during service. The project trains a graduate student and two undergraduate students in the areas of high temperature materials, thin film technology, and microfabrication, and K-12 students are being educated about high temperature materials science. Collaborations with industrial partners are being used to evaluate the effectiveness of the new coatings that are developed. TECHNICAL DETAILS:Ceramic thin film coatings that can withstand harsh environments with service temperatures of 1000-1500oC must exhibit excellent heat resistance, chemical stability, fracture toughness and wear durability. Conventional ceramic coatings crack and delaminate during service because of interdiffusion phenomena, chemical reactivity, and stress generation during thermal cycling in reactive gases at extreme temperatures. This project focuses on developing and testing SiAlON and SiZrON films that are precisely fabricated using magnetron sputtering and ECR-plasma-assisted e-beam evaporation. Nanoscale architectures are being investigated including gradient and multilayer compositions in order to achieve high performance in terms of corrosion resistance, wear resistance, and fracture toughness. To efficiently test and evaluate coating performance under thermal cycling conditions, a microfabricated MEMS test platform is being developed that consists of microheaters, temperature sensors, oxidation sensors, stress indicators, and microsliding fixtures. The project trains a graduate student and two undergraduate students in the areas of high temperature materials, thin film technology, and microfabrication, and K-12 students are being educated about high temperature materials science. Collaborations with industrial partners are being pursued to evaluate the effectiveness of the SiAlON and SiZrON coatings

Linear Taylor–Couette stability of a transversely isotropic fluid

Fibre-laden fluids are found in a variety of situations, while Couette devices are used for flow spectroscopy of long biological molecules, such as DNA and proteins in suspension. The presence of these fibres can significantly alter the rheology of the fluid, and hence must be incorporated in any modelling undertaken. A transversely isotropic fluid treats these suspensions as a continuum with an evolving preferred direction, through a modified stress tensor incorporating four viscosity-like parameters. We consider the axisymmetric linear stability of a transversely isotropic viscous fluid, contained between two rotating co-axial cylinders, and determine the critical wave and Taylor numbers for varying gap width and inner cylinder velocity (assuming the outer cylinder is fixed). Through the inclusion of transversely isotropic effects, the onset of instability is delayed, increasing the range of stable operating regimes. This effect is felt most strongly through incorporation of the anisotropic shear viscosity, although the anisotropic extensional viscosity also contributes. The changes to the rheology induced by the presence of the fibres therefore significantly alter the dynamics of the system, and hence should not be neglected

Projected health effects of realistic dietary changes to address freshwater constraints in India : a modelling study

Acknowledgements This study forms part of the Sustainable and Healthy Diets in India project supported by the Wellcome Trust's Our Planet, Our Health programme (grant number 103932). LA's PhD is funded by the Leverhulme Centre for Integrative Research on Agriculture and Health. SA is supported by a Wellcome Trust Capacity Strengthening Strategic Award-Extension phase (grant number WT084754/Z/08/A). We would like to thank Zaid Chalabi (London School of Hygiene & Tropical Medicine) for providing valuable guidance on the modelling methods.Peer reviewedPublisher PD

Biomolecule Detection \u3cem\u3evia\u3c/em\u3e Target Mediated Nanoparticle Aggregation and Dielectrophoretic Impedance Measurement

A new biosensing system is described that is based on the aggregation of nanoparticles by a target biological molecule and dielectrophoretic impedance measurement of these aggregates. The aggregation process was verified within a microchannel via fluorescence microscopy, demonstrating that this process can be used in a real time sensor application. Positive dielectrophoresis is employed to capture the nanoparticle aggregates at the edge of thin film electrodes, where their presence is detected either by optical imaging via fluorescence microscopy or by measuring the change in electrical impedance between adjacent electrodes. The electrical detection mechanism demonstrates the potential for this method as a micro total analysis system (mTAS)

Col-OSSOS: Colors of the Interstellar Planetesimal 1I/`Oumuamua

The recent discovery by Pan-STARRS1 of 1I/2017 U1 (`Oumuamua), on an unbound and hyperbolic orbit, offers a rare opportunity to explore the planetary formation processes of other stars, and the effect of the interstellar environment on a planetesimal surface. 1I/`Oumuamua's close encounter with the inner Solar System in 2017 October was a unique chance to make observations matching those used to characterize the small-body populations of our own Solar System. We present near-simultaneous g$^\prime$, r$^\prime$, and J photometry and colors of 1I/`Oumuamua from the 8.1-m Frederick C. Gillett Gemini North Telescope, and $gri$ photometry from the 4.2 m William Herschel Telescope. Our g$^\prime$r$^\prime$J observations are directly comparable to those from the high-precision Colours of the Outer Solar System Origins Survey (Col-OSSOS), which offer unique diagnostic information for distinguishing between outer Solar System surfaces. The J-band data also provide the highest signal-to-noise measurements made of 1I/`Oumuamua in the near-infrared. Substantial, correlated near-infrared and optical variability is present, with the same trend in both near-infrared and optical. Our observations are consistent with 1I/`Oumuamua rotating with a double-peaked period of $8.10 \pm 0.42$ hours and being a highly elongated body with an axial ratio of at least 5.3:1, implying that it has significant internal cohesion. The color of the first interstellar planetesimal is at the neutral end of the range of Solar System $g-r$ and $r-J$ solar-reflectance colors: it is like that of some dynamically excited objects in the Kuiper belt and the less-red Jupiter Trojans.Comment: Accepted to ApJ

Estimating the Permanent Loss of Groundwater Storage in the Southern San Joaquin Valley, California

In the San Joaquin Valley, California, recent droughts starting in 2007 have increased the pumping of groundwater, leading to widespread subsidence. In the southern portion of the San Joaquin Valley, vertical subsidence as high as 85 cm has been observed between June 2007 and December 2010 using Interferometric Synthetic Aperture Radar (InSAR). This study seeks to map regions where inelastic (not recoverable) deformation occurred during the study period, resulting in permanent compaction and loss of groundwater storage. We estimated the amount of permanent compaction by incorporating multiple data sets: the total deformation derived from InSAR, estimated skeletal-specific storage and hydraulic parameters, geologic information, and measured water levels during our study period. We used two approaches, one that we consider to provide an estimate of the lowest possible amount of inelastic deformation, and one that provides a more reasonable estimate. These two approaches resulted in a spatial distribution of values for the percentage of the total deformation that was inelastic, with the former estimating a spatially averaged value of 54%, and the latter a spatially averaged value of 98%. The former corresponds to the permanent loss of 4.14*108 m3 of groundwater storage, or roughly 5% of the volume of groundwater used over the study time period; the latter corresponds to the loss of 7.48*108 m3 of groundwater storage, or roughly 9% of the volume of groundwater used. This study demonstrates that a data-driven approach can be used effectively to estimate the permanent loss of groundwater storage

IGERT: Sensor Science, Engineering, and Informatics

This Sensor Science, Engineering and Informatics (SSEI) IGERT program will provide multidisciplinary doctoral training in the area of sensor systems ranging from the science and engineering of new materials and sensing mechanisms to the interpretation of sensor data. The design and management of effective sensor systems requires a holistic understanding of how information is collected, stored, integrated, evaluated, and communicated within sensing systems and to decision makers in diverse application contexts. The SSEI IGERT weaves together three research focus areas: (1) Sensor Materials and Devices, (2) Sensor Systems and Networks, and (3) Sensor Informatics. The intellectual merit of the project includes education and research activities that are designed to ensure a feedback loop so that SSEI IGERT trainees are able to transform new knowledge from sensor-generated data to further development of sensor systems and networks and advances in sensor materials and devices, and vice versa. Innovative components of the program include (1) development and use of a testbed prototype that will require interdisciplinary interaction across the three research areas; (2) a tight integration of the social, legal, ethical, and economic dimensions of sensing environments in both research and training, (3) expanded relationships with companies and federal laboratories engaged in sensor research, (4) international collaborations, and (5) synergistic integration with sensor science and engineering education at the middle, high school, and undergraduate level. The broader impacts of the SSEI IGERT program are a new breed of scientists and engineers who will be versatile in dealing with the diverse technical components that contribute to sensing systems, knowledgeable in the legal, social, and ethical contexts of heavily sensed environments, and aware of the human values that must be preserved, protected and promoted within such systems. IGERT is an NSF-wide program intended to meet the challenges of educating U.S. Ph.D. scientists and engineers with the interdisciplinary background, deep knowledge in a chosen discipline, and the technical, professional, and personal skills needed for the career demands of the future. The program is intended to catalyze a cultural change in graduate education by establishing innovative new models for graduate education and training in a fertile environment for collaborative research that transcends traditional disciplinary boundaries

Weaber Plain hydrogeology: preliminary results

In 2008, the Ord Irrigation Expansion Project was approved by the Western Australian Government to develop irrigated agriculture on the Weaber Plain. Construction of the M2 supply channel connecting the ORIA and Weaber Plain, and the final period of irrigation design, environmental management and related approval processes commenced later in 2009. This process followed a protracted period of public and private industry planning and environmental assessment (Kinhill 2000). As a part of the environmental planning and approvals process, the WA Government was required to prepare a groundwater management plan and a hydrodynamic plan. These plans were to address potential issues of salinity and water quality that may result from developing the proposed farmlands