Influence of excess Si distribution in the gate oxide on the memory characteristics of MOSFETs

In this work, Si ions are implanted into the gate oxide of MOSFETs with different implantation schemes, followed by a high-temperature annealing. The memory characteristics of the MOSFETs have been investigated for the following two excess Si distributions: (1) the excess Si is distributed in a narrow layer in the gate oxide near the Si substrate; and (2) the excess Si is distributed throughout the gate oxide. It is observed that both the excess Si distributions have good endurance of up to 10⁶ program/erase cycles. The second excess Si distribution exhibits a better retention characteristic with less than 50% charge loss after 10 years. In contrast, the first excess Si distribution shows a complete charge loss after 1 year. PACS 73.22.-f; 73.63.Bd; 81.07.Bc     

Mechanical and optical design for assembly of vascular endothelial cells using laser guidance and tweezers

Laser is applied to guide and tweeze the vascular endothelial cells for assembly. The system is composed of three modules: laser guidance, micro channels and laser tweezers. The micro channel includes the assembly area, main channel and branch channels. The optical module is equipped with laser source, beam splitter, reflectors and lenses. The endothelial cells are delivered to main channel and guided through branch channel to the assembly area by laser. The optical tweezers then move the cells to the proper position. The design of optical modules is conducted for the maximum capability of manipulating cells. The micro channel is designed based on fluid mechanics to minimize the fluidic disturbance to the cells in the assembly area, and is fabricated by photo lithography. Polystyrene micro beads and endothelial cells are successfully guided and tweezed by this approach. The associated escape velocity and dragging force are investigated.     

Novel pressure-induced magnetic transition in magnetite (Fe3O4)

Fe K-edge x-ray magnetic circular dichroism of magnetite (Fe3O4) powders was measured with synchrotron radiation under variable pressure and temperature conditions in diamond anvil cell. The magnetic dichroism was observed to decrease discontinuously by approximately 50% between 12 and 16 GPa, independent of temperature. The magnetic transition is attributed to a high-spin to intermediate-spin transition of Fe2+ ions in the octahedral sites and could account for previously observed structural and electrical anomalies in magnetite at this pressure range. The interpretation of x-ray magnetic circular dichroism data is supported by x-ray emission spectroscopy and theoretical cluster calculations.     

Statistical properties of agent-based models in markets with continuous double auction mechanism

Real world markets display power-law features in variables such as price fluctuations in stocks. To further understand market behavior, we have conducted a series of market experiments on our web-based prediction market platform which allows us to reconstruct transaction networks among traders. From these networks, we are able to record the degree of a trader, the size of a community of traders, the transaction time interval among traders and other variables that are of interest. The distributions of all these variables show power-law behavior. On the other hand, agent-based models have been proposed to study the properties of real financial markets. We here study the statistical properties of these agent-based models and compare them with the results from our web-based market experiments. In this work, three agent-based models are studied, namely, zero-intelligence (ZI), zero-intelligence-plus (ZIP) and Gjerstad-Dickhaut (GD). Computer simulations of variables based on these three agent-based models were carried out. We found that although being the most naive agent-based model, ZI indeed best describes the properties observed in real markets. Our study suggests that the basic ingredient to produce the observed properties from real world markets could in fact be the result of a continuously evolving dynamical system with basic features similar to the ZI model.     

Large negative differential resistance in graphene nanoribbon superlattices

A graphene nanoribbon superlattice with a large negative differential resistance (NDR) is proposed. Our results show that the peak-to-valley ratio (PVR) of the graphene superlattices can reach 21 at room temperature with bias voltages between 90–220 mV, which is quite large compared with the one of traditional graphene-based devices. It is found that the NDR is strongly influenced by the thicknesses of the potential barrier. Therefore, the NDR effect can be optimized by designing a proper barrier thickness. The large NDR effect can be attributed to the splitting of the gap in transmission spectrum (segment of Wannier–Stark ladder) with larger thicknesses of barrier when the applied voltage increases.     

Direct coupling of capillary electrophoresis and nuclear magnetic resonance spectroscopy for the identification of a dinucleotide

Summary In this paper, a general peak capacity expression was evaluated using columns containing various packing materials under solvating gas chromatography (SGC) conditions. Differing from column efficiency, peak capacity can describe both separation capability and speed when introducing the dead time into the peak capacity expression. Various factors that influence peak capacity in SGC are described, including particle pore size, chemical surface modification, particle size, column length, temperature, and pressure.     

Sodium Phytate-Incorporated Gelatin-Silicate Nanoplatelet Composites for Enhanced Cohesion and Hemostatic Function of Shear-Thinning Biomaterials

Shear-thinning biomaterials (STBs) based on gelatin-silicate nanoplatelets (SNs) are emerging as an alternative to conventional coiling and clipping techniques in the treatment of vascular anomalies. Improvements in the cohesion of STB hydrogels pave the way toward their translational application in minimally invasive therapies such as endovascular embolization repair. In the present study, sodium phytate (Phyt) additives are used to tune the electrostatic network of SNs-gelatin STBs, thereby promoting their mechanical integrity and facilitating injectability through standard catheters. We show that an optimized amount of Phyt enhances storage modulus by approximately one order of magnitude and reduces injection force by ≈58% without compromising biocompatibility and hydrogel wet stability. The Phyt additives are found to decrease the immune responses induced by SNs. In vitro embolization experiments suggest a significantly lower rate of failure in Phyt-incorporated STBs than in control groups. Furthermore, the addition of Phyt leads to accelerated blood coagulation (reduces clotting time by ≈45% compared to controls) due to the contributions of negatively charged phosphate groups, which aid in the prolonged durability of STB in coagulopathic patients. Therefore, the proposed approach is an effective method for the design of robust and injectable STBs for minimally invasive treatment of vascular malformations.     

Recombinant Multi-l-Arginyl-Poly-l-Aspartate (Cyanophycin) as an Emerging Biomaterial

Multi-l -arginyl-poly-l -aspartate (MAPA) is a non-ribosomal polypeptide which synthesis is directed by cyanophycin synthetase, and its production can be achieved using recombinant microorganisms carrying the cphA gene. Along its poly-aspartate backbone, arginine or lysine links to each aspartate via an isopeptide bond. MAPA is a zwitterionic polyelectrolyte full of charged carboxylic, amine, and guanidino groups. In aqueous solution, MAPA exhibits dual thermal and pH responses similar to those stimuli-responsive polymers. Being biocompatible, the films containing MAPA can support cell proliferation and elicits minimal immune response in macrophages. Dipeptides from MAPA after enzymatic treatments can provide nutritional benefits. In light of the increasing interest in MAPA, this article focuses on the recent discovery of the function of cyanophycin synthetase and the potentials of MAPA as a biomaterial.     

The highly efficient protein crystallography beamline TLS 13B1 at the National Synchrotron Radiation Research Center

Synchrotron protein crystallography (PX) is one of the most powerful and dominant tools for determining the three-dimensional structures of biological macromolecules. At the National Synchrotron Radiation Research Center, TLS 13B1 is the first dedicated energy-tunable and highly automated PX beamline for efficiently solving de novo protein structures in Taiwan and has been open for users since September 2005. With remote access, user support services, and annual PX training courses over 17 years, the number of user groups at TLS 13B1 has grown from 11 to 139. In total, 1,429 projects were supported, and 2090 experiments were hosted during 67,846 hr of beamtime. This paper describes the photon source, beamline components, experimental station equipment, beamline software, beamline application process, and results from our users.     

Ultrasound and surfactant-assisted dispersive liquid–liquid microextraction prior to poly(ethylene oxide)-mediated stacking in CE for highly sensitive determination of barbiturates in human fluids

This study developed a facile, highly sensitive technique for extracting and quantifying barbiturates in serum samples. This method combined ultrasound and surfactant-assisted dispersive liquid–liquid microextraction with poly(ethylene oxide)-mediated stacking in capillary electrophoresis. Factors influencing the extraction and stacking performance, such as the type and volume of extraction solvents, the type and concentration of surfactant, extraction time, salt additives, sample matrix, solution pH, and composition of the background electrolyte, were carefully studied and optimized to achieve the optimal detection sensitivity. Under the optimized extraction (injecting 140 μL C₂H₄Cl₂ into 1 mL of sample with pH 4 (5 mM sodium phosphate containing 0.05 mM Tween 20 and sonication for 1 min) and separation conditions (150 mM tris(hydroxymethyl)aminomethane-borate with pH 8.5 containing 0.5% (m/v) poly(ethylene oxide)), the limits of detection (signal-to-noise ratio = 3) of five barbiturates ranged from 0.20 to 0.33 ng/mL, and the calculated sensitivity improvement ranged from 868- to 1700-fold. The experimental results revealed excellent linearity (R² > 0.99), with relative standard deviations of 2.1%–3.4% for the migration time and 4.3%–5.7% for the peak area. The recoveries of the spiked serum samples were 97.1% –110.3%. Our proposed approach offers a rapid and practical method for quantifying barbiturates in biological fluids.