Effect of Initial Grain Size on Friction Stir Weldability for Rolled and Cast CoCrFeMnNi High-Entropy Alloys

Metals and Materials International - This study investigated the influence of the initial grain size on the plastic deformation and tunnel defects that occurred from friction stir welding of...     

Characteristics of negative electron beam resists, ma-N2410 and ma-N2405

We have characterized the electron beam lithography (EBL) properties of the new negative tone resists, ma-N2410 and ma-N2405. These negative resists reacts under low electron dose values from 10 to 140 μC/cm², tested using 10, 20, 28 keV electron beam. There was negligible loss of pattern height, which was attributed to the combined dose of the incident electron beam and the backscattered electrons. Experimental tests were performed under various EBL writing conditions of dose value, developing time, line-width and resist thickness. Our investigation showed that these new commercially available resists have high resolution and high contrast with non-chemical amplification, useful for micro-fabrication application.     

LSPR-based colorimetric biosensing for food quality and safety

Ensuring consistently high quality and safety is paramount to food producers and consumers alike. Wet chemistry and microbiological methods provide accurate results, but those methods are not conducive to rapid, onsite testing needs. Hence, many efforts have focused on rapid testing for food quality and safety, including the development of various biosensors. Herein, we focus on a group of biosensors, which provide visually recognizable colorimetric signals within minutes and can be used onsite. Although there are different ways to achieve visual color-change signals, we restrict our focus on sensors that exploit the localized surface plasmon resonance (LSPR) phenomenon of metal nanoparticles, primarily gold and silver nanoparticles. The typical approach in the design of LSPR biosensors is to conjugate biorecognition ligands on the surface of metal nanoparticles and allow the ligands to specifically recognize and bind the target analyte. This ligand–target binding reaction leads to a change in color of the test sample and a concomitant shift in the ultraviolet-visual absorption peak. Various designs applying this and other signal generation schemes are reviewed with an emphasis on those applied for evaluating factors that compromise the quality and safety of food and agricultural products. The LSPR-based colorimetric biosensing platform is a promising technology for enhancing food quality and safety. Aided by the advances in nanotechnology, this sensing technique lends itself easily for further development on field-deployable platforms such as smartphones for onsite and end-user applications.     

Preparation of PLLA/PBAT‐strengthened degradable expanded polystyrene

To enhance the flexural strength of degradable expanded polystyrene (DEPS) while maintaining degradability, during the manufacturing processes of DEPS, cerium(III) stearate (CeSt₃) and poly‐L‐lactide (PLLA)/poly(butylene adipate‐co‐terephthalate) (PBAT) are used as a nontoxic oxidizer and a co‐biodegradable polymer filler, respectively. The flexural strength of DEPS is decreased by the oxidizer and increased by the biodegradable polymers. Furthermore, by favorable interfacial interaction between PLLA and PBAT, the flexural strength is more enhanced when the two biodegradable polymers are used simultaneously than used separately. The photo‐, bio‐ and oxo‐degradation behaviors of DEPS were evaluated by UV irradiation, thermal treatments, landfill, and non‐landfill tests. Molecular weight of our DEPS is decreased to 90.26% after 2 weeks of UV irradiation and 74.4% after 3 months of thermal treatment test. 35.4 and 31.4% of weight of our DEPS is reduced after 3 months of landfill and non‐landfill test. It is confirmed that the decomposition period of DEPS could be adjusted by controlling the amount of the oxidizer and/or the biodegradable polymers. The FT‐IR study demonstrated that oligomers and nonylphenol which are known to cause the environmental hazards are not generated after the degradation of DEPS. POLYM. ENG. SCI., 57:883–890, 2017. © 2016 Society of Plastics Engineers     

Effects of forest type and environmental factors on forest carbon use efficiency assessed using MODIS and FIA data across the eastern USA

The carbon use efficiency (CUE) of a forest, calculated as the ratio of net primary productivity (NPP) to gross primary productivity (GPP), measures how efficiently a forest sequesters atmospheric carbon. Some prior research has suggested that CUE varies with environmental conditions, while other suggests that CUE is constant. Research using Moderate Resolution Imaging Spectroradiometer (MODIS) data has indicated a variable CUE, but those results are suspected because MODIS NPP data have not been well validated.

We tested two questions. First, whether MODIS CUE is constant or whether it varies by forest type, climate, and geographic factors across the eastern USA. Second, whether those results occur when field-based NPP data are employed. We used MODIS model-based estimates of GPP and NPP, and forest inventory and anlaysis (FIA) field-based estimates of NPP data. We calculated two estimates of CUE for forest in 390 km² hexagons: (1) MODIS CUE as MODIS NPP divided by MODIS GPP and (2) F/M Z_CUE as the standardized difference between FIA NPP and MODIS GPP.

MODIS CUE and F/M Z_CUE both varied similarly and significantly in relation to forest type, and climatic and geographic factors, strongly supporting a variable rather than a constant CUE. The CUE was significantly higher in deciduous than in mixed and evergreen forests. Regression models indicated that CUE decreased with increases in temperature and precipitation and increased with latitude and altitude. The similar trends in MODIS CUE and F/M Z_CUE support the use of the more easily obtained MODIS CUE.     

A Low Cost Utility Interactive Inverter for Residential Fuel Cell Generation

This paper presents the development of a single-phase utility-interactive inverter for residential power generation to meet the specifications laid down for the 2005 Future Energy Challenge Competition sponsored by U.S. DOE and IEEE. The proposed inverter system is capable of working in both stand-alone and grid-connected mode. A control scheme for implementing both modes of operation is presented, which has simple structure with smaller number of sensors. The proposed control algorithm including the whole system control is implemented on a low cost, fixed-point DSP TMS320F2812. The experimental results from a 1 kW prototype show that the proposed inverter system exhibits not only low THD grid current during the grid-connected mode and well regulated inverter voltage during the stand-alone mode, but also smooth and automatic transfer between the two modes of operation.     

Benzenedithiol: a broad-range single-channel molecular conductor

More than a decade after the first report of single-molecule conductance, it remains a challenging goal to prove the exact nature of the transport through single molecules, including the number of transport channels and the origin of these channels from a molecular orbital point of view. We demonstrate for the archetypical organic molecule, benzenedithiol (BDT), incorporated into a mechanically controllable break junction at low temperature, how this information can be deduced from studies of the elastic and inelastic current contributions. We are able to tune the molecular conformation and thus the transport properties by displacing the nanogap electrodes. We observe stable contacts with low conductance in the order of 10(-3) conductance quanta as well as with high conductance values above ～0.5 quanta. Our observations show unambiguously that the conductance of BDT is carried by a single transport channel provided by the same molecular level, which is coupled to the metallic electrodes, through the whole conductance range. This makes BDT particularly interesting for applications as a broad range coherent molecular conductor with tunable conductance.     

Supercooling preservation technology in food and biological samples: a review focused on electric and magnetic field applications

Food Science and Biotechnology - Freezing has been widely recognized as the most common process for long-term preservation of perishable foods; however, unavoidable damages associated with ice...     

Charge transport characteristics of diarylethene photoswitching single-molecule junctions

We report on the experimental analysis of the charge transport through single-molecule junctions of the open and closed isomers of photoswitching molecules. Sulfur-free diarylethene molecules are developed and studied via electrical and optical measurements as well as density functional theory calculations. The single-molecule conductance and the current-voltage characteristics are measured in a mechanically controlled break-junction system at low temperatures. Comparing the results with the single-level transport model, we find an unexpected behavior of the current-dominating molecular orbital upon isomerization. We show that both the side chains and end groups of the molecules are crucial to understand the charge transport mechanism of photoswitching molecular junctions.