Photodynamic Inactivation of an Endodontic Bacteria Using Diode Laser and Indocyanine Green-Loaded Nanosphere

Apical periodontitis, an inflammatory lesion causing bone resorption around the apex of teeth, is treated by eradicating infectious bacteria from the root canal. However, it has a high recurrence rate and often requires retreatment. We investigated the bactericidal effect of antimicrobial photodynamic therapy (aPDT)/photodynamic antimicrobial chemotherapy (PACT) using indocyanine green (ICG)-loaded nanospheres coated with chitosan and a diode laser on a biofilm of Enterococcus faecalis, a pathogen of refractory apical periodontitis. Biofilm of E. faecalis was cultured in a porcine infected root canal model. ICG solution was injected into the root canal, which was then irradiated with a laser (810 nm wavelength) from outside the root canal. The bactericidal effect was evaluated by colony counts and scanning electron microscopy. The result of the colony counts showed a maximum 1.89 log reduction after irradiation at 2.1 W for 5 min. The temperature rise during aPDT/PACT was confirmed to be within a safe range. Furthermore, the light energy transmittance through the root was at a peak approximately 1 min after the start of irradiation, indicating that most of the ICG in the root canal was consumed. This study shows that aPDT/PACT can suppress E. faecalis in infected root canals with high efficiency.     

Metrics for focusing in extremely noisy scanning electron microscopy condition

Finding a best focused image in very noisy condition is an extremely difficult task for the SEM user. If a performance, which is much higher than that of an expert in focusing, can be achieved in a computer-controlled scanning electron microscope (SEM), it will be very helpful for our field due to the many possible applications. To accomplish this work, we employ a powerful metric-the covariance obtained by a special scanning method. It can select the best focused image from a series of SEM images acquired by altering the focus of the objective lens under an extremely noisy SEM image condition. The noise immunity of the present method is quantitatively evaluated, and it is further improved based on the obtained evaluation result.     

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 of Polyaniline Films with Different Doping Concentrations of (±)-10-Camphorsulfonic Acid

The temperature dependence of the thermoelectric properties was investigated for polyaniline (PANI) films doped with different concentrations of (±)-10-camphorsulfonic acid (CSA) with molar ratio x of CSA to two phenyl-nitrogen units of x = 1 to 0.2. All PANI-CSA films exhibit p-type conduction. The temperature dependence of the electrical conductivity of the films with low CSA concentrations is consistent with a transport mechanism of variable-range hopping. On the other hand, the Seebeck coefficient above room temperature shows a linear increase with temperature, attributed to the metallic nature of PANI-CSA. As the CSA concentration decreases, the absolute value of the Seebeck coefficient increases while the electrical conductivity extremely decreases, probably due to the changes not only in the carrier concentration but also in the degree of structural disorder. The power factor increases monotonically with increasing CSA concentration toward x = 1 (the maximum limit). The thermal conductivity value of CSA-PANI film with x = 1 is as low as about 0.20 W m^?1 K^?1 in the through-plane direction and about 0.67 W m^?1 K^?1 in the in-plane direction. The thermoelectric figure of merit ZT in the in-plane direction is estimated to be approximately 1 × 10^?3 for x = 1.     

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.     

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.     

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.     

A method using an on-line digital computer for the improvement of resolution of backscattered electron images

In principle, the resolution of backscattered electron (BSE) images can be little improved, even though an infinitely small beam size is achieved by various improvements in the intrinsic instrument. In order to circumvent this problem, a method is proposed which utilizes an on-line digital computer for the image recording and processing. The major image-processing tools are reduction, expansion, super-imposition with matching of the images, and high-emphasis filtering in the Fourier domain. By using various combinations of these techniques, the resolution of BSE images has been significantly improved. The validity of these improved images has been confirmed. In the case of a BSE image with too wide a dynamic range, both the present method and digital homomorphic filtering provide successful results.     

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.