The conversion of a field-emission scanning electron microscope to a high-resolution,high-performance scanning transmission electron microscope,while maintaining original functions

Recently, the reliability of field-emission electron guns has increased. In addition, the cost of computer systems for on-line processing has dropped. Hence, we should now consider the use of scanning transmission electron microscopy (STEM) for routine work, especially, in the field of biology where one may expect to utilize digital image processing techniques. An STEM has been constructed, without disturbing the original functions, by converting a commercial scanning electron microscope equipped with a fieldemission gun. The STEM is generally operated at accelerating voltage 30 kV, focal length 7.5 mm, and beam current 1?2 × 10^?10 A. Several improvements have been incorporated for removing the effects of vibration, contamination, and stray magnetic fields. Also, an adjustable detector aperture was utilized. The modified instrument was connected to an on-line digital image processing system for utilizing the information obtained from STEM images. The advantages of the modified system were studied from various viewpoints.     

An improved scanning method based on characteristics of the human visual system for scanning electron microscopy

An improved scanning method for the scanning electron microscope (SEM) is proposed. Here, quincuncial scanning (sampling) instead of a conventional (raster) scanning is used. This scanning method is very effective for quality improvement of an SEM image obtained under undersampling conditions (rough sampling). The present study focuses on characteristics of the human visual system, specifically the low response of eyes in diagonal directions. When using this method coupled with a high-precision interpolation, the number of pixels necessarily doubles. It is not surprising that it is advantageous for printing. A more important advantage is the fact that SEM images can be acquired with a shorter recording time. Hence, this type of scanning will be helpful for quick and frequent recordings in a "snapshot" mode, which up to now has not been achieved successfully by SEM.     

Gelatin Methacryloyl–Riboflavin (GelMA–RF) Hydrogels for Bone Regeneration

Gelatin methacryloyl (GelMA) is a versatile biomaterial that has been used in various biomedical fields. UV light is commonly used to photocrosslink such materials; however, its use has raised several biosafety concerns. We investigated the mechanical and biological properties of a visible-wavelength (VW)-light-crosslinked gelatin-based hydrogel to evaluate its viability as a scaffold for bone regeneration in bone-destructive disease treatment. Irgacure2959 or riboflavin was added as a photoinitiator to create GelMA solutions. GelMA solutions were poured into a mold and exposed to either UV or VW light. KUSA-A1 cell-laden GelMA hydrogels were crosslinked and then cultured. Mechanical characterization revealed that the stiffness range of GelMA–RF hydrogel was suitable for osteoblast differentiation. KUSA-A1 cells encapsulated in GelMA hydrogels photopolymerized with VW light displayed significantly higher cell viability than cells encapsulated in hydrogels photopolymerized with UV light. We also show that the expression of osteogenesis-related genes at a late stage of osteoblast differentiation in osteoblasts encapsulated in GelMA–RF hydrogel was markedly increased under osteoblast differentiation-inducing conditions. The GelMA–RF hydrogel served as an excellent scaffold for the encapsulation of osteoblasts. GelMA–RF hydrogel-encapsulated osteoblasts have the potential not only to help regenerate bone mass but also to treat complex bone defects associated with bone-destructive diseases such as periodontitis.     

Thermoelectric Properties and Thermal Stability of PEDOT:PSS Films on a Polyimide Substrate and Application in Flexible Energy Conversion Devices

In this study, we investigated the flexibility and thermal stability of films consisting of a complex of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) cast onto a polyimide substrate. We also prepared a PEDOT:PSS-based flexible device for thermoelectric energy conversion. The thermal stability of a PEDOT:PSS film was evaluated by measuring the Seebeck coefficient (S) and electrical conductivity (σ) for 30 heating and cooling cycles at 330 K to 380 K. Furthermore, the durability of the PEDOT:PSS film was examined by heating at 353 K in air for 4000 h. The approximate values of S and σ were 14 μV K^?1 and 600 S cm^?1, respectively. These values were almost the same before and after repeated bending treatments (10,000 times, radius of curvature 10 mm). In addition, the S and σ values for the PEDOT:PSS film were nearly constant during the heating cycle treatments. In the durability test, σ gradually decreased with increasing heating time (7% at 300 h, 17% at 3600 h). Thus, it was found that PEDOT:PSS films have both flexibility and mechanical toughness as well as relatively good thermal stability in air up to 3600 h. The maximum electric power for the PEDOT:PSS-based flexible device was 0.334 μW at ΔT = 100 K. These results for the power-generating properties of the flexible device are consistent with values calculated from the properties of the constituent materials.     

Electromigration Behaviors and Effects of Addition Elements on the Formation of a Bi-rich Layer in Sn58Bi-Based Solders

This study investigates the electromigration (EM) behaviors and effects of the addition elements on the formation of a Bi-rich layer in Sn58Bi-based solders including Sn58Bi (SB), Sn58Bi0.5Ag (SBA) and Sn58Bi0.5Ag0.1Cu0.07Ni0.01Ge (SBACNG) solders. The EM tests were conducted at a relatively high temperature of 373 K and at a current density of 30 kA/cm². Although the dominant diffusing atom was Bi, hillocks were formed from Sn more easily than from Bi. The electrical resistance increased in the solder during the current stressing, and the dominant factor was attributed to the formation of a Bi-rich layer. SBACNG solder showed the highest resistance to the formation of a Bi-rich layer, followed by SBA, and then SB solder. The possible addition elements enhancing the resistance of SBACNG solder are Ag, Ni and Ge. The effects of the addition elements are summarized as follows: (1) Ag distributes in the Sn phase as Ag₃Sn intermetallic compounds (IMCs) that enhance the mechanical strength of Sn; (2) Ni distribution in Bi as Ni-Bi IMCs stabilizes Bi and suppresses its migration; and (3) Ge may distribute in Bi, stabilizing Bi, or Ge exists at the phase boundaries as a precipitate that inhibits Bi migration.     

Practical method for noise removal in scanning electron microscopy

A new smoothing filter has been developed for noise removal of scanning electron microscopy (SEM) images. We call this the complex hysteresis smoothing (CHS) filter. It is much easier to use for SEM operators than any other conventional smoothing filter, and it rarely produces processing artifacts because it does not utilize a definite mask (which usually has processing parameters of size, shape, weight, and the number of iterations) like a common averaging filter or a complicated filter shape in the Fourier domain. Its criterion for distinguishing noise depends simply on the amplitude of the SEM signal. When applied to several images with different characteristics, it is shown that the present method has a high performance with some original advantages.     

SODEL FET: novel channel and source/drain profile engineering schemes by selective Si epitaxial growth technology

In this paper, novel channel and source/drain profile engineering schemes are proposed for sub-50-nm bulk CMOS applications. This device, referred to as the silicon-on-depletion layer FET (SODEL FET), has the depletion layer beneath the channel region, which works as an insulator like a buried oxide in a silicon-on-insulator MOSFET. Thanks to this channel structure, junction capacitance (C/sub j/) has been reduced in SODEL FET, i.e., C/sub j/ (area) was /spl sim/0.73 fF//spl mu/m/sup 2/ both in SODEL nFET and pFET at Vbias =0.0 V. The body effect coefficient /spl gamma/ is also reduced to less than 0.02 V/sup 1/2/. Nevertheless, current drives of 886 /spl mu/A//spl mu/m (I/sub off/=15 nA//spl mu/m) in nFET and -320 /spl mu/A//spl mu/m (I/sub off/=10 nA//spl mu/m) in pFET have been achieved in 70-nm gate length SODEL CMOS with |V/sub dd/|=1.2 V. New circuit design schemes are also proposed for high-performance and low-power CMOS applications using the combination of SODEL FETs and bulk FETs on the same chip for 90-nm-node generation and beyond.     

Extract of fermented barley attenuates chronic alcohol induced liver damage by increasing antioxidative activities

Chronic consumption of alcohol leads to liver disorders primarily as hepatosteatosis, and increase of oxidative stress. The abundance of these reactive oxygen species (ROS) is a result of ethanol (ethyl alcohol) oxidation by alcohol dehydrogenase and cytochrome p450 2E1 (CYP2E1). In order to address this problem with natural substance, the high polyphenol content of barley has been numerously cited to provide excellent antioxidative effect. In this study, we investigated the effect of fermented barley extract (FBE) in chronic ethanol fed female Wistar rats. We obtained significant decrease of plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in the FBE supplemented group. Further examinations revealed that FBE induces substantial improvement in hepatic gene expressions of key anti-oxidative genes, reinforced by its increase of enzymatic activities and subsequent suppression of oxidative stress. Thus we have demonstrated a novel approach for the use of barley as supplements to attenuate chronic alcohol consumption.     

A productive and cost-effective CBN hard milling-based fabrication method of hardened sliding guideways made of refined cast iron

Sliding guideways have received renewed interest in recent years as machine tool linear motion guides, due to a demand for machine tools to have good dynamic performance, which is of vital importance when machining difficult-to-cut materials. While the traditional fabrication approach of the sliding surface is grinding, this paper investigated the possibility of an alternative cubic boron nitride (CBN) milling-based manufacturing approach while utilizing Al and Mg additives in the cast iron material for better machinability and productivity. Machining results have shown a dramatic improvement in machinability especially in terms of tool wear at certain cutting conditions with the refined hardened cast iron and a CBN tool. It was found by the post experimental analysis that oxide films of the Al and Mg additives were generated at the cutting edge of the CBN tool to protect the tool from wear. Because of suppression of tool wear, a very constant surface roughness can also be achieved. A case study has also demonstrated the effectiveness of the CBN milling-based manufacturing approach with the refined cast iron and the found high-speed cutting conditions.     

Presumptive technique of power generation of amorphous silicon cell including various factors

This paper describes the presumptive technique of power generation of amorphous silicon module considering various factors. The influences exerted by solar spectrum, spectral response, angle of incidence and efficiency deviation are evaluated. Then, various factors are formulated. The presumptive technique of power generation including these factors is examined. As a result, the proposal technique is able to presume with a high accuracy as compared with the conventional technique.