Device-Algorithm Co-Optimization for an On-Chip Trainable Capacitor-Based Synaptic Device with IGZO TFT and Retention-Centric Tiki-Taka Algorithm.

Analog in-memory computing synaptic devices are widely studied for efficient implementation of deep learning. However, synaptic devices based on resistive memory have difficulties implementing on-chip training due to the lack of means to control the amount of resistance change and large device variations. To overcome these shortcomings, silicon complementary metal-oxide semiconductor (Si-CMOS) and capacitor-based charge storage synapses are proposed, but it is difficult to obtain sufficient retention time due to Si-CMOS leakage currents, resulting in a deterioration of training accuracy. Here, a novel 6T1C synaptic device using only n-type indium gaIlium zinc oxide thin film transistor (IGZO TFT) with low leakage current and a capacitor is proposed, allowing not only linear and symmetric weight update but also sufficient retention time and parallel on-chip training operations. In addition, an efficient and realistic training algorithm to compensate for any remaining device non-idealities such as drifting references and long-term retention loss is proposed, demonstrating the importance of device-algorithm co-optimization.

Inhibitory Effects of Chrysanthemum boreale Essential Oil on Biofilm Formation and Virulence Factor Expression of Streptococcus mutans.

The aim of the study was to evaluate the antibacterial activity of essential oil extracted from Chrysanthemum boreale (C. boreale) on Streptococcus mutans (S. mutans). To investigate anticariogenic properties, and bacterial growth, acid production, biofilm formation, bacterial adherence of S. mutans were evaluated. Then gene expression of several virulence factors was also evaluated. C. boreale essential oil exhibited significant inhibition of bacterial growth, adherence capacity, and acid production of S. mutans at concentrations 0.1-0.5 mg/mL and 0.25-0.5 mg/mL, respectively. The safranin staining and scanning electron microscopy results showed that the biofilm formation was also inhibited. The result of live/dead staining showed the bactericidal effect. Furthermore, real-time PCR analysis showed that the gene expression of some virulence factors such as gtfB, gtfC, gtfD, gbpB, spaP, brpA, relA, and vicR of S. mutans was significantly decreased in a dose dependent manner. In GC and GC-MS analysis, seventy-two compounds were identified in the oil, representing 85.42% of the total oil. The major components were camphor (20.89%), ß-caryophyllene (5.71%), α-thujone (5.46%), piperitone (5.27%), epi-sesquiphellandrene (5.16%), α-pinene (4.97%), 1,8-cineole (4.52%), ß-pinene (4.45%), and camphene (4.19%). These results suggest that C. boreale essential oil may inhibit growth, adhesion, acid tolerance, and biofilm formation of S. mutans through the partial inhibition of several of these virulence factors.

Organic-on-silicon complementary metal-oxide-semiconductor colour image sensors.

Complementary metal-oxide-semiconductor (CMOS) colour image sensors are representative examples of light-detection devices. To achieve extremely high resolutions, the pixel sizes of the CMOS image sensors must be reduced to less than a micron, which in turn significantly limits the number of photons that can be captured by each pixel using silicon (Si)-based technology (i.e., this reduction in pixel size results in a loss of sensitivity). Here, we demonstrate a novel and efficient method of increasing the sensitivity and resolution of the CMOS image sensors by superposing an organic photodiode (OPD) onto a CMOS circuit with Si photodiodes, which consequently doubles the light-input surface area of each pixel. To realise this concept, we developed organic semiconductor materials with absorption properties selective to green light and successfully fabricated highly efficient green-light-sensitive OPDs without colour filters. We found that such a top light-receiving OPD, which is selective to specific green wavelengths, demonstrates great potential when combined with a newly designed Si-based CMOS circuit containing only blue and red colour filters. To demonstrate the effectiveness of this state-of-the-art hybrid colour image sensor, we acquired a real full-colour image using a camera that contained the organic-on-Si hybrid CMOS colour image sensor.

Kaurenoic Acid from Aralia continentalis Inhibits Biofilm Formation of Streptococcus mutans.

We isolated a single chemical compound from A. continentalis and identified it to be kaurenoic acid (KA) and investigated the influence of anticariogenic properties. Inhibitory effects of KA on cariogenic properties such as growth, acid production, biofilm formation, and the adherence of S. mutans were evaluated. Furthermore, real-time PCR analysis was performed to evaluate the influence of KA on the genetic expression of virulence factors. KA significantly inhibited the growth and acid production of S. mutans at 2-4 µ g/mL and 4 µ g/mL of KA, respectively. Furthermore, the adherence onto S-HAs was inhibited at 3-4 µ g/mL of KA and biofilm formation was significantly inhibited when treated with 3 µ g/mL KA and completely inhibited at 4 µ g/mL. Also, the inhibitory effect of KA on biofilm formation was confirmed by SEM. In confocal laser scanning microscopy, bacterial viability gradually decreased by KA in a dose dependent manner. Real-time PCR analysis showed that the expressions of gtfB, gtfC, gbpB, spaP, brpA, relA, and vicR were significantly decreased in S. mutans when it was treated with KA. These results suggest that KA from A. continentalis may be a useful agent for inhibiting the cariogenic properties of S. mutans.

Evaluation of the antiviral activity of a green tea solution as a hand-wash disinfectant.

Based on the broad-spectrum antiviral effect of green tea catechins, we established an experimental skin contact model for influenza virus transmission and evaluated the use of a green tea solution as a first-hand disinfectant. The infectivity of the virus on the skin cell layer became obsolete when washed with the green tea solution. The skin contact model could be applied to develop non-pharmaceutical intervention measures for reducing human transmission of the influenza virus.

The RPT2 subunit of the 26S proteasome directs complex assembly, histone dynamics, and gametophyte and sporophyte development in Arabidopsis.

The regulatory particle (RP) of the 26S proteasome contains a heterohexameric ring of AAA-ATPases (RPT1-6) that unfolds and inserts substrates into the core protease (CP) for degradation. Through genetic analysis of the Arabidopsis thaliana gene pair encoding RPT2, we show that this subunit plays a critical role in 26S proteasome assembly, histone dynamics, and plant development. rpt2a rpt2b double null mutants are blocked in both male and female gamete transmission, demonstrating that the subunit is essential. Whereas rpt2b mutants are phenotypically normal, rpt2a mutants display a range of defects, including impaired leaf, root, trichome, and pollen development, delayed flowering, stem fasciation, hypersensitivity to mitomycin C and amino acid analogs, hyposensitivity to the proteasome inhibitor MG132, and decreased 26S complex stability. The rpt2a phenotype can be rescued by both RPT2a and RPT2b, indicative of functional redundancy, but not by RPT2a mutants altered in ATP binding/hydrolysis or missing the C-terminal hydrophobic sequence that docks the RPT ring onto the CP. Many rpt2a phenotypes are shared with mutants lacking the chromatin assembly factor complex CAF1. Like caf1 mutants, plants missing RPT2a or reduced in other RP subunits contain less histones, thus implicating RPT2 specifically, and the 26S proteasome generally, in plant nucleosome assembly.

Essential oil of Curcuma longa inhibits Streptococcus mutans biofilm formation.

Curcuma longa (C. longa) has been used as a spice in foods and as an antimicrobial in Oriental medicine. In this study, we evaluated the inhibitory effects of an essential oil isolated from C. longa on the cariogenic properties of Streptococcus mutans (S. mutans), which is an important bacterium in dental plaque and dental caries formation. First, the inhibitory effects of C. longa essential oil on the growth and acid production of S. mutans were tested. Next, the effect of C. longa essential oil on adhesion to saliva-coated hydroxyapatite beads (S-HAs) was investigated. C. longa essential oil inhibited the growth and acid production of S. mutans at concentrations from 0.5 to 4 mg/mL. The essential oil also exhibited significant inhibition of S. mutans adherence to S-HAs at concentrations higher than 0.5 mg/mL. S. mutans biofilm formation was determined by scanning electron microscopy (SEM) and safranin staining. The essential oil of C. longa inhibited the formation of S. mutans biofilms at concentrations higher than 0.5 mg/mL. The components of C. longa essential oil were then analyzed by GC and GC-MS, and the major components were α-turmerone (35.59%), germacrone (19.02%), α-zingiberene (8.74%), αr-turmerone (6.31%), trans-ß-elemenone (5.65%), curlone (5.45%), and ß-sesquiphellandrene (4.73%). These results suggest that C. longa may inhibit the cariogenic properties of S. mutans.

Broad-spectrum antiviral effect of Agrimonia pilosa extract on influenza viruses.

Influenza virus continues to emerge and re-emerge, posing new threats for humans. Here we tested various Korean medicinal plant extracts for potential antiviral activity against influenza viruses. Among them, an extract of Agrimonia pilosa was shown to be highly effective against all three subtypes of human influenza viruses including H1N1 and H3N2 influenza A subtypes and influenza B virus. The EC(50) value against influenza A virus, as tested by the plaque reduction assay on MDCK cells, was 14-23 microg/ml. The extract also exhibited a virucidal effect at a concentration of 160-570 ng/ml against influenza A and B viruses when the viruses were treated with the extract prior to plaque assay. In addition, when tested in embryonated chicken eggs the extract exhibited a strong inhibitory effect in ovo on the H9N2 avian influenza virus at a concentration of 280 ng/ml. Quantitative RT-PCR analysis data showed that the extract, to some degree, suppressed viral RNA synthesis in MDCK cells. HI and inhibition of neuraminidase were observed only at high concentrations of the extract. And yet, the extract's antiviral activity required direct contact between it and the virus, suggesting that its antiviral action is mediated by the viral membrane, but does not involve the two major surface antigens, HA and NA, of the virus. The broad-spectrum antiviral activity of Agrimonia pilosa extract on various subtypes of influenza viruses merits further investigation as it may provide a means of managing avian influenza infections in poultry farms and potential avian-human transmission.

Elevation of glutamine level by selenophosphate synthetase 1 knockdown induces megamitochondrial formation in Drosophila cells.

Although selenophosphate synthetase 1 (SPS1/SelD) is an essential gene in Drosophila, its function has not been determined. To elucidate its intracellular role, we targeted the removal of SPS1/SelD mRNA in Drosophila SL2 cells using RNA interference technology that led to the formation of vacuole-like globular structures. Surprisingly, these structures were identified as megamitochondria, and only depolarized mitochondria developed into megamitochondria. The mRNA levels of l(2)01810 and glutamine synthetase 1 (GS1) were increased by SPS1/SelD knockdown. Blocking the expression of GS1 and l(2)01810 completely inhibited the formation of megamitochondria induced by loss of SPS1/SelD activity and decreased the intracellular levels of glutamine to those of control cells suggesting that the elevated level of glutamine is responsible for megamitochondrial formation. Overexpression of GS1 and l(2)01810 had a synergistic effect on the induction of megamitochondrial formation and on the synthesis of glutamine suggesting that l(2)01810 is involved in glutamine synthesis presumably by activating GS1. Our results indicate that, in Drosophila, SPS1/SelD regulates the intracellular glutamine by inhibiting GS1 and l(2)01810 expression and that elevated levels of glutamine lead to a nutritional stress that provides a signal for megamitochondrial formation.

The RPN5 subunit of the 26s proteasome is essential for gametogenesis, sporophyte development, and complex assembly in Arabidopsis.

The 26S proteasome is an essential multicatalytic protease complex that degrades a wide range of intracellular proteins, especially those modified with ubiquitin. Arabidopsis thaliana and other plants use pairs of genes to encode most of the core subunits, with both of the isoforms often incorporated into the mature complex. Here, we show that the gene pair encoding the regulatory particle non-ATPase subunit (RPN5) has a unique role in proteasome function and Arabidopsis development. Homozygous rpn5a rpn5b mutants could not be generated due to a defect in male gametogenesis. While single rpn5b mutants appear wild-type, single rpn5a mutants display a host of morphogenic defects, including abnormal embryogenesis, partially deetiolated development in the dark, a severely dwarfed phenotype when grown in the light, and infertility. Proteasome complexes missing RPN5a are less stable in vitro, suggesting that some of the rpn5a defects are caused by altered complex integrity. The rpn5a phenotype could be rescued by expression of either RPN5a or RPN5b, indicating functional redundancy. However, abnormal phenotypes generated by overexpression implied that paralog-specific functions also exist. Collectively, the data point to a specific role for RPN5 in the plant 26S proteasome and suggest that its two paralogous genes in Arabidopsis have both redundant and unique roles in development.

Biological evaluation of anti-influenza viral activity of semi-synthetic catechin derivatives.

Catechin derivatives with different alkyl chain length and aromatic ring substitutions at the 3-hydroxyl group were synthesized from epigallocatechin (EGC) and (+)-catechin (C) and their anti-influenza viral activity were evaluated in vitro and in ovo. Pronounced antiviral activity was observed for derivatives carrying moderate chain length (7-9 carbons) as compared to those with aromatic rings, whereas the 5'-hydroxyl group of the trihydroxy benzyl moiety did not significantly contribute to antiviral activity. The derivatives exerted inhibitory effects for all six influenza subtypes tested including three major types of currently circulating human influenza viruses (A/H1N1, A/H3N2 and B type), H2N2 and H9N2 avian influenza virus. The compounds strongly inhibited adsorption of the viruses on red blood cell (RBC). They also restricted the growth of avian influenza virus in ovo with minimum inhibition concentration (MIC) of 5-10 microM far exceeding the neuraminidase (NA) inhibitor oseltamivir or M2 proton channel inhibitor amantadine. The antiviral activity appears to be mediated by interaction with hemagglutinin (HA)/viral membrane rendering HA less fusogenic at the initial stage of infection. The broad spectrum activity against various subtypes of influenza viruses may complement the limitations of current antivirals and contribute for managing potentially emerging influenza pandemic. The structure-activity data of catechin derivatives may usefully guideline future research endeavors for applying green tea catechins as alternative anti-viral agents.

Antiviral effect of catechins in green tea on influenza virus.

Polyphenolic compound catechins ((-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG) and (-)-epigallocatechin (EGC)) from green tea were evaluated for their ability to inhibit influenza virus replication in cell culture and for potentially direct virucidal effect. Among the test compounds, the EGCG and ECG were found to be potent inhibitors of influenza virus replication in MDCK cell culture and this effect was observed in all influenza virus subtypes tested, including A/H1N1, A/H3N2 and B virus. The 50% effective inhibition concentration (EC50) of EGCG, ECG, and EGC for influenza A virus were 22-28, 22-40 and 309-318 microM, respectively. EGCG and ECG exhibited hemagglutination inhibition activity, EGCG being more effective. However, the sensitivity in hemagglutination inhibition was widely different among three different subtypes of influenza viruses tested. Quantitative RT-PCR analysis revealed that, at high concentration, EGCG and ECG also suppressed viral RNA synthesis in MDCK cells whereas EGC failed to show similar effect. Similarly, EGCG and ECG inhibited the neuraminidase activity more effectively than the EGC. The results show that the 3-galloyl group of catechin skeleton plays an important role on the observed antiviral activity, whereas the 5'-OH at the trihydroxy benzyl moiety at 2-position plays a minor role. The results, along with the HA type-specific effect, suggest that the antiviral effect of catechins on influenza virus is mediated not only by specific interaction with HA, but altering the physical properties of viral membrane.