Unipolar bistable switching of organic non-volatile memory devices with poly(styrene-co-styrenesulfonic acid Na).

We demonstrated unipolar organic bistable memory devices with 8 x 8 cross-bar array type structure. The active material for the organic non-volatile memory devices is poly(styrene-co-styrenesulfonic acid Na) (PSSANa). From the electrical measurements of the PSSANa organic memory devices, we observed rewritable unipolar switching behaviors with a stable endurance and narrow cumulative probability. Also the PSSANa memory devices exhibited a uniform cell-to-cell switching with a high ON/OFF ratio of approximately 10(5) and good retention time of approximately 10(4) seconds without significant degradation.

Removal of cetyltrimethylammonium bromide to enhance the biocompatibility of Au nanorods synthesized by a modified seed mediated growth process.

Previously, we reported the synthesis of stable gold nanorods with higher aspect ratio (approximately 15-20) and more enhanced uniformity by a modified seed mediated growth approach using a binary surfactant system consisting of CTAB and Pluronic F-127. For the in vivo application of gold nanorods, the removal of CTABs that are strongly bound on prepared Au nanorods is necessary due to their cytotoxicity. Use of heat or acid at various conditions was performed to achieve the complete removal of CTAB from the synthesized Au nanorods while maintaining their stability. Here, we report the appropriate conditions for both treatments that can remove CTAB efficiently without hampering the stability of Au nanorods. After the removal of CTAB, Pluronic F-127 was added additionally for the stabilization and further potential functionalization of Au nanorods to make useful for various applications. VIS-NIR absorption spectroscopy, SEM, TEM, and FTIR were used for characterization.

Comparison of Si doping effect on GaN nanowires and films synthesized by metal-organic chemical vapor deposition.

We investigated Si doping effect on GaN nanowires and GaN films grown by metal-organic chemical vapor deposition (MOCVD). Si as n-type dopant is incorporated to GaN nanowires and GaN films controlled by SiH4 flow rate (0, 1, 5, 8, and 10 sccm). The charge concentration and mobility of GaN films increased and decreased, respectively, as increasing the SiH4 flow rate, whereas those for GaN nanowires were not influenced by the SiH4 flow rate. Significant vacancies and impurities resulted in the intense yellow band in GaN nanowires as compared with GaN films, which leads to the large device-to-device variation and negligible dependence of Si doping and the SiH4 flux rate on the electrical properties of GaN nanowires.

Memory characteristics of a self-assembled monolayer of Pt nanoparticles as a charge trapping layer.

A self-assembled monolayer of Pt nanoparticles (NPs) was studied as a charge trapping layer for non-volatile memory (NVM) applications. Pt NPs with a narrow size distribution (diameter ∼4 nm) were synthesized via an alcohol reduction method. The monolayer of these Pt NPs was immobilized on a SiO(2) substrate using poly(4-vinylpyridine) (P4VP) as a surface modifier. A metal-oxide-semiconductor (MOS) type memory device with Pt NPs exhibits a relatively large memory window of 5.8 V under ± 7 V for program/erase voltage. These results indicate that the self-assembled Pt NPs can be utilized for NVM devices.

Development and validation of an automated thawing and mixing workcell.

BACKGROUND: Working toward a goal of total laboratory automation, we are automating manual activities in our highest volume laboratory section. Because half of all specimens arriving in this laboratory section are frozen, we began by developing an automated workcell for thawing frozen specimens and mixing the thawed specimens to remove concentration gradients resulting from freezing and thawing. METHODS: We developed an initial robotic workcell that removed specimens from the transport system's conveyor, blew high-velocity room temperature air at the tubes, mixed them, and replaced them on the conveyor. Aliquots of citrated plasma were frozen with thermocouples immersed in the tubes, and thawing times and temperatures were monitored. Completeness of mixing of thawed specimens was studied by careful removal of small aliquots from the uppermost layer of the upright tubes without disturbing tube contents and analysis of total protein and electrolytes. RESULTS: High velocity ambient air aimed directly at tubes ranging from 12 x 75 to 16 x 100 mm brought specimens to room temperature in a maximum of 23 min. Adequate mixing of the specimens by the workcell's robot required only 2 approximate 126 degrees movements from an upright starting point, a surprising observation, because laboratorians are usually trained to mix 10 or 20 times. We also observed that, in a frozen overfilled tube, resulting analyte concentrations will be lower because more concentrated solutes leak from the tube. CONCLUSIONS: A high-throughput, automated thawing and mixing workcell was successfully built, validated, and installed on our automated transport and sorting system.