Enhancing copper infiltration into alumina using spark plasma sintering to achieve high performance Al2O3/Cu composites

Al2O3/Cu (with 30 wt% of Cu) composites were prepared using a combined liquid infiltration and spark plasma sintering (SPS) method using pre-processed composite powders. Crystalline structures, morphology and physical/mechanical properties of the sintered composites were studied and compared with those obtained from similar composites prepared using a standard liquid infiltration process without any external pressure. Results showed that densities of the Al2O3/Cu composites prepared without applying pressure were quite low. Whereas the composites sintered using the SPS (with a high pressure during sintering in 10 minutes) showed dense structures, and Cu phases were homogenously infiltrated and dispersed with a network from inside the Al2O3 skeleton structures. Fracture toughness of Al2O3/Cu composites prepared without using external pressure (with a sintering time of 1.5 hours) was 4.2 MPa·m1/2, whereas that using the SPS process was 6.5 MPa·m1/2. These toughness readings were increased by 18% and 82%, respectively, compared with that of pure alumina. Hardness, density and electrical resistivity of the samples prepared without pressure were 693 HV, 82.5% and 0.01Ω•m, whereas those using the SPS process were 842 HV, 99.1%, 0.002Ω•m, respectively. The enhancement in these properties using the SPS process are mainly due to the efficient pressurized infiltration of Cu phases into the network of Al2O3 skeleton structures, and also due to high intensity discharge plasma which produces fully densified composites in a short time

Association between polymorphisms in the promoter region of the apolipoprotein E (APOE) gene and Alzheimers disease

Several studies have evaluated the role of polymorphisms in the promoter region of APOE gene that encodes apolipoprotein E (APOE) and the susceptibility to Alzheimer’s disease (AD). The aim of this literature review and meta-analysis was to investigate the relationship between the APOE promoter region single nucleotide polymorphisms (SNPs) (rs449647, -491A/T; rs769446, -427T/C and rs405509 -219T/G) and the risk of developing AD. Eligible controlled studies published up to November 2016 were retrieved from main online scientific and medical databases. Odds ratio (OR) and 95 % confidence interval (CI) were used to calculate the strength of the relationship. A total of 23 publications (19 for rs449647, ten for rs769446 and ten for rs405509) were retrieved that included 5,703 patients with AD and 5,692 controls. The C allele of the rs769446 variant of the promoter region of APOE gene was significantly associated with an increase of risk of AD (OR = 1.271, 95 % CI = 1.114–1.449, P < 0.0001), while other genetic models of this variant were not related with susceptibility to AD. Rs449647 and rs405509 polymorphisms of APOE gene were not associated with an increase of risk of AD. The findings of this literature review and meta-analysis have shown that rs769446 polymorphism in the promoter region of APOE gene could be a risk factor for AD. Future large-scale studies on the role of polymorphisms in the promoter region of APOE gene in AD are still awaited

Fabrication of the 0.346 THz BWO for Plasma Diagnostic

Nuclear fusion is probably the most demanding challenge the scientific community is facing. The plasma is a delicate material that has to be properly shaped to achieve a high efficiency fusion process. Unfortunately, the plasma is affected by micro-turbulences still not fully understood, detrimental for the reactor functioning. The diagnostic of plasma is a fundamental technique that needs advanced approaches for a full mapping of the plasma behavior. The 0.346 THz backward wave oscillator is the enabling devices for a high-k plasma diagnostic that will provide unprecedented insight on turbulences leading to full operational fusion reactors. This paper describes the final fabrication phase of the 0.346 THz BWO for plasma diagnostic jointly performed in an international project, involving three leading institutions in vacuum electronics

Fabrication of the 0.346 THz BWO for Plasma Diagnostic

Nuclear fusion is probably the most demanding challenge the scientific community is facing. The plasma is a delicate material that has to be properly shaped to achieve a high efficiency fusion process. Unfortunately, the plasma is affected by micro-turbulences still not fully understood, detrimental for the reactor functioning. The diagnostic of plasma is a fundamental technique that needs advanced approaches for a full mapping of the plasma behavior. The 0.346 THz backward wave oscillator is the enabling devices for a high-k plasma diagnostic that will provide unprecedented insight on turbulences leading to full operational fusion reactors. This paper describes the final fabrication phase of the 0.346 THz BWO for plasma diagnostic jointly performed in an international project, involving three leading institutions in vacuum electronics

THz backward-wave oscillators for plasma diagnostic in nuclear fusion

Understanding of the anomalous transport attributed to short-scale length microturbulence through collective scattering diagnostics is key to the development of nuclear fusion energy. Signals in the subterahertz (THz) range (0.1–0.8 THz) with adequate power are required to map wider wavenumber regions. The progress of a joint international effort devoted to the design and realization of novel backward-wave oscillators at 0.346 THz and above with output power in the 1 W range is reported herein. The novel sources possess desirable characteristics to replace the bulky, high maintenance, optically pumped far-infrared lasers so far utilized in this plasma collective scattering diagnostic. The formidable fabrication challenges are described. The future availability of the THz source here reported will have a significant impact in the field of THz applications both for scientific and industrial applications, to provide the output power at THz so far not available

Nanoscale surface roughness effects on THz vacuum electron device performance

Vacuum electron devices are the most promising solution for the generation of watt-level power at millimeter wave and terahertz frequencies. However, the three dimensional nature of metal structures required to provide an effective interaction between an electron beam and THz signal poses significant fabrication challenges. At increasing frequency, losses present a serious detrimental effect on performance. In particular, the skin depth, on the order of one hundred nanometers or less, constrains the maximum acceptable surface roughness of the metal surfaces to be below those values. Microfabrication techniques have proven, in principle, to achieve values of surface roughness at the nanometer scale; however, the use of different metals and affordable microfabrication techniques requires further investigation for a repeatable quality of the metal surfaces. This paper compares, for the first time, the nanoscale surface roughness of metal THz waveguides realized by the main microfabrication techniques. In particular, two significant examples are considered: a 0.346 THz backward wave tube oscillator and a 0.263 THz traveling wave tube

Fabrication of 0.346 THz BWO for Plasma Diagnostics

Nuclear fusion energy is perhaps one of the most demanding challenges the scientific community is facing. Unfortunately, the plasma is affected by micro-turbulence, which is still not fully understood, but which can degrade plasma confinement. The 0.346 THz backward wave oscillator is the enabling device for a high-k plasma collective scattering diagnostic that will provide unprecedented insight on turbulence thereby contributing to the realization of fully operational fusion reactors. This paper describes the final fabrication phase of the 0.346 THz backward wave oscillator for the collective scattering diagnostic jointly performed in an international project, involving three leading institutions in vacuum electronics. The advancements in technology will open the route to new families of THz vacuum electron devices to enable new THz applications and provide industry with new advanced processes

Eco-Driving for Transit

DTRT13-G-UTC29Eco-driving has significant potential to reduce fuel consumption and emissions from transit operations. Analyses were conducted of 68 thousand miles of real-world operations data from 26 buses, collected from local transit service provided by the Metropolitan Atlanta Rapid Transit Authority (MARTA), and express bus service provided by the Georgia Regional Transportation Authority (GRTA). The analysis utilized second-by-second operations data collected via global positioning system (GPS) devices from buses operated by these transit agencies

A Tool to Predict Fleet-Wide Heavy-Duty Vehicle Fuel-Saving Benefits from Low Rolling Resistance Tires

The cost of fuel represents a major portion of the costs of operating on-road heavy-duty vehicles (HDV). According to the American Transportation Research Institute, fuel costs alone amounted to about 25 percent of truck operating costs in 2015. Within the U.S. on-road transportation sector HDVs consume a disproportionately high amount of the total refined petroleum-based fuel and carbon dioxide emissions from consumption of this fuel were estimated to be equivalent to over 400 million metric tons. HDVs also contributed a disproportionately high 2.5 million short tons of Oxides of Nitrogen (NOx) emissions, emitted as a by-product of fuel combustion in on-road vehicle engines. NOx is a precursor of ozone, which is an air pollutant harmful to humans, plants, and animals. Over the next couple of decades, the total energy demand from the HDV sector will likely increase due to forecasted growth in freight demand in many global markets, including the United States, and much of this energy will continue to be provided by fossil fuels. Therefore, carbon dioxide emissions from the HDV sector are also expected to increase in the absence of effective mitigating measures to reduce the sectors reliance on fossil fuels. In this study, the authors develop a tool to predict the fleet-wide fuel-saving benefits from low rolling resistance tires. Unlike previous studies, the developed tool is applicable to both stabilized speed operations and transient speed operations. The tool is based on empirical models that estimate the fuel consumption contribution from tires as a function of vehicle payload, aerodynamic drag, road grade, duration of acceleration, duration of deceleration and, and road facility type (freeway, major arterial, and minor arterial/local road). The authors limited the scope of the developed tool to tractor-trailers in the U.S. heavy-duty vehicle market, because the United States has the second largest HDV market in the world and tractor-trailers account for the largest share of the market. The tool was developed with data generated by simulating real-world heavy-duty vehicle operating cycles with Autonomie\uae, the state-of-the-art model for automotive control-system design, and simulating vehicle energy consumption and performance. Autonomie\uae is a preferred vehicle simulation tool of the United States Department of Energy

Emissions Benefits from Reducing Local Transit Service Deadheading: An Atlanta Case Study

DTRT13-G-UTC29Citation: Hanyan Li, Haobing Liu, Xiaodan Xu, Yanzhi (Ann) Xu, Michael O. Rodgers, and Randall L. Guensler (2016) Emissions Benefits from Reducing Local Transit Service Deadheading: An Atlanta Case Study, 95th Transportation Research Board Annual Meeting Compendium of Papers, Washington, D.C., Issue 16-6385.The paper showcases the strategies for reducing deadheading in the planning process for transit agencies, and the analysis herein, conducted for the Atlanta region, can be easily applied to other agencies across the nation