Current image tunneling spectroscopy of boron-doped nanodiamonds

[[abstract]]The electron field emission properties of the nanodiamond films were examined using scanning tunneling microscopic sSTMd technique. Current image tunneling spectroscopic measurements reveal the direct dependence of electron tunneling/field emission behavior of the films on the proportion of grain boundaries present. Local tunneling current-voltage sIt–Vd measurements show that incorporation of boron species insignificantly alters the occupied state, but markedly modifies the empty state of the diamond films, viz. it induces the presence of impurity states for the films heavily doped with borons, resulting in smaller emission energy gap for the samples. Such a characteristic improves both the local electron field emission behavior of the diamond films measured by STM and the average electron field emission properties measured by conventional parallel plate setup. These results infer clearly that the presence of impurity states due to boron doping is a prime factor improving the field emission properties for these boron-doped nanodiamond films.[[notice]]補正完畢[[journaltype]]國內[[booktype]]紙

Enhanced electron field emission properties by tuning the microstructure of ultrananocrystalline diamond film

[[abstract]]Synthesis of microcrystalline-ultrananocrystalline compositediamond (MCD-UNCD) films, which exhibit marvelous electron field emission (EFE) properties, was reported. The EFE of MCD-UNCD compositediamondfilm can be turned on at a low field as 6.5 V/μm and attain large EFE current density about 1.0 mA/cm2 at 30 V/μm applied field, which is better than the EFE behavior of the nondoped planar diamondfilms ever reported. The MCD-UNCD films were grown by a two-step microwave plasma enhanced chemical vapor deposition (MPECVD) process, including forming an UNCD layer in CH4/Ar plasma that contains no extra H2, followed by growingMCD layer using CH4/H2/Ar plasma that contains large proportion of H2. Microstructure examinations using high resolution transmission electron microscopy shows that the secondary MPECVD process modifies the granular structure of the UNCD layer, instead of forming a large grain diamond layer on top of UNCDfilms. The MCD-UNCD compositediamondfilms consist of numerous ultrasmall grains (∼5 nm in size), surrounding large grains about hundreds of nanometer in size. Moreover, there exist abundant nanographites in the interfacial region between the grains that were presumed to form interconnected channels for electron transport, resulting in superior EFE properties for MCD-UNCD compositefilms.[[incitationindex]]SCI[[booktype]]電子版[[booktype]]紙

Growth behavior of nanocrystalline diamond films on ultrananocrystalline diamond nuclei: The transmission electron microscopy studies

[[abstract]]Micron-crystalline diamond (MCD) films with a unique microstructure were synthesized using a modified nucleation and growth process, in which a thin layer of ultrananocrystalline diamond (UNCD) was used as nucleation layer for growing diamond films in H2-plasma. Thus obtained (MCD)UNCD diamond films consist of nanosized diamond clusters ( ∼ 10 nm in size) surrounding the large diamond grains ( ∼ 300 nm in size), exhibiting better electron field emission (EFE) properties than the conventional diamond materials with faceted grains. The EFE of these (MCD)UNCD films can be turned on at E0 = 11.1 V/μm, achieving EFE current density as large as (Je) = 0.7 mA/cm2 at 25 V/μm applied field, which can be attributed to the presence of large proportion of UNCD grains lying in between the MCD grains, forming an electron conduction path and thus facilitating the EFE process. Transmission electron microscopy examinations reveal that such a unique microstructure was formed by agglomeration and coalescence of the nanosized UNCD grains.[[incitationindex]]SCI[[incitationindex]]EI[[booktype]]紙

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Dielectric and optical properties of electroceramic PBZNZT thin films prepared by pulsed laser deposition process

100學年度研究獎補助論文[[abstract]]The 0.6[0.94Pb(Zn1/3Nb2/3)O3 + 0.06BaTiO3] + 0.4[0.48(PbZrO3) + 0.52(PbTiO3)], PBZNZT, thin films were synthesized by pulsed laser deposition (PLD) process. The PBZNZT films possess higher insulating characteristics than the PZT (or PLZT) series materials due to the suppressed formation of defects, therefore, thin-film forms of these materials are expected to exhibit superior ferroelectric properties as compared with the PZT (or PLZT)-series thin films. Moreover, the Ba(Mg1/3Ta2/3)O3 thin film of perovskite structure was used as buffer layer to reduce the substrate temperature necessary for growing the perovskite phase PBZNZT thin films. The PBZNZT thin films of good ferroelectric and dielectric properties (remanent polarization Pr = 26.0 μC/cm2, coercive field Ec = 399 kV/cm, dielectric constant K = 737) were achieved by PLD at 400°C. Such a low substrate temperature technique makes this process compatible with silicon device process. Moreover, thus obtained PBZNZT thin films also possess good optical properties (about 75% transmittance at 800 nm). These results imply that PBZNZT thin films have potential in photonic device applications.[[incitationindex]]SCI[[incitationindex]]EI[[booktype]]紙

Evanescent microwave probe study on dielectric properties of materials

[[abstract]]A recently developed evanescent microwave probe (EMP) technique combined with systematically quantitative analyses is demonstrated. We use a three-dimensional (3D) finite element simulation to model the electromagnetic field inside the resonant cavity and inside the sample near the tip. We also proposed an analysis model for the sample's quality factor (Q), which is usually hindered by the conductor losses of the resonator. Measurement on various dielectric samples agrees very well with the theoretical model, demonstrating the validity of analyses for the EMP resonator and providing a possibility for dielectric imaging the surface of the samples with high resolution.[[notice]]補正完

Correlation of microwave dielectric properties and crystallinity for pulsed laser deposited Bi2(Zn1/3Nb2/3)2O7 thin films

[[abstract]]Correlation of microwave dielectric properties of Bi2(Zn1/3Nb2/3)2O7, BiZN thin films, which were pulsed laser deposited on Si(100) substrates, with crystallinity of BiZN phase was examined using Fourier Transform Infrared (FTIR) spectroscopy. Rigid-ion model analysis from FTIR spectra of the films reveals that the magnitude of effective charge for oxygen increases with improved crystallinity for BiZN films. In contrast, lattice vibrational modes of the films, which occur at ω01=341 cm−1, ω02=522 cm−1, and ω03=612 cm−1, insignificantly change with films' crystallinity. It implies that better crystallinity will induce higher polarization in BO6 oxygen octahedral, which improves microwave properties of pyrochlore materials. The dielectric constant measured at 200 cm−1 increases with substrate temperature used for depositing BiZN films, inferring that dielectric properties in low frequency regime of far infrared region are predominantly contributed by ionic polarization, and are strongly related to effective charges of oxygen species.[[notice]]補正完

Protective Effects of One 2,4-Dihydro-3H-Pyrazol-3-one Derivative against Posterior Capsular Opacification by Regulation of TGF-β2/SMADs and Non-SMAD Signaling, Collagen I, and Fibronectin Proteins

Many elderly individuals frequently experience cataracts that interfere with vision. After cataract surgery, the left lens epithelial cell (LEC) exhibited fibrosis and posterior capsule opacification (PCO). Sometimes, there is a need for a second surgery; nevertheless, people try other methods, such as a good pharmacological agent, to treat PCO to reduce transforming growth factor-β2 (TGF-β2) amounts to avoid secondary surgery. The aim of the present study was to explore the potential anti-PCO activity of five 2,4-dihydro-3H-pyrazol-3-one (DHPO) derivatives in a TGF-β2-induced fibrogenesis SRA01/04 cell model. The 2-phenyl-5-propyl-DHPO (TSE; no. 2: TSE-2) compound showed the best activity of reduced expression levels of TGF-β2 among five derivatives and therefore was chosen to evaluate the anti-PCO activity and molecular mechanisms on the Sma and mad protein (SMAD) signaling pathway (including TGF-β2, SMADs, and the inhibition of nuclear translocation of SMADs), non-SMAD pathway proteins, including p-extracellular, regulated protein kinases (ERK) 1/2, or p-c-Jun N-terminal kinase (JUN) by Western blotting, PCR, or confocal immunofluorescence analyses. Following treatment with 10 μg/mL of the five compounds, the cells displayed great viability by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTT) assay. In this study, the result of lactate dehydrogenase (LDH) activity measurement did not affect the cytotoxicity of the five compounds. In TGF-β2-induced fibrogenesis in SRA01/04 cells, treatment with the TSE compound decreased the TGF-β2/SMAD signaling genes, including reduced mRNA or expression levels of TGF-β2, SMAD3, and SMAD4, leading to inhibition of TGF-β2-induced fibrogenesis. Our confocal immunofluorescence analyses demonstrated that TSE treatment displays a suppressive effect on SMAD2/3 or SMAD4 translocation to the nucleus. Furthermore, TSE treatment exhibits a reduction in the non-SMAD target gene expression levels of p- c-Jun N-terminal kinase (JUN), p- extracellular, regulated protein kinases (ERK)1/2, p- p38 mitogen-activated protein kinase (p38), p-phosphatidylinositol 3-kinase (PI3K), p-mammalian target of rapamycin complex (mTORC), p-Akt (Ser473), and p-Akt (Thr308). The overall effect of TSE is to reduce the expression levels of collagen I and fibrinogen (FN), thus contributing to antifibrotic effects in cell models mimicking PCO. Our findings reveal the benefits of TSE by regulating TGF-β/SMAD signaling and non-SMAD signaling-related gene proteins to display antifibrotic activity in cells for the possibility of preventing PCO after cataract surgery