Shoot organogenesis and somatic embryogenesis in leaf tissue of Pulsatilla tongkangensis Y.N. Lee & T.C. Lee

Zhao Xiao-mei,Lian Yu-ji,Jin Ze-lin,Zhang Xue-jie,Y Yan,Fan Shou-jin 한국식물생명공학회 2022 Plant biotechnology reports Vol.16 No.4

Leaf material explants of Pulsatilla tongkangensis Y. N. Lee & T. C. Lee were used to regenerate plants of this endangered species by somatic embryogenesis and organogenesis from meristematic nodules, induced by MS medium supplemented with zeatin (Zn) and indole-3-acetic acid (IAA). Globular structures were induced on the surface of the explants after 2 weeks and after 6–7 weeks of culture, multiple shoots developed from the nodules. Morpho-histological analysis of light green globular, heart-shaped structures resembling somatic embryos revealed, however, that these were organogenic, with strongly vacuolated parenchymatous cells surrounded by a single layer of epithermal cells, and tracheid elements, but no root pole. Milky-white callus also developed around the nodules after 4–6 weeks. Morpho-histological analysis of the globular, heart-, and torpedo-shaped stages of regenerants present in this callus confirmed the development of somatic embryos in the milky-white structures, characterized by deeply staining, small cells with rich cytoplasm, very little vascular tissue in the developing embryos, and no vascular connection with the surrounding callus. The highest rooting frequency (93.33%) was achieved on MS medium containing 1.5 mg/l NAA. Plantlets were acclimatized and successfully transferred to pots. Our results provide a plant regeneration system with potential for germplasm conservation of endangered plants and the rapid propagation and molecular breeding of P. tongkangensis.

Thermoelectric properties of Gd, Y co-doped Ca3Co4O9+δ

H.Q. Liu,X.B. Zhao,T.J. Zhu,Y. Song,F.P. Wang 한국물리학회 2009 Current Applied Physics Vol.9 No.3

The Ca3-x-yGdxYyCo4O9+δ precursor powders were synthesized by the polyacrylamide gel method. The powders were sintered by the spark plasma sintering (SPS). The DTA analysis showed that the synthesis temperature of Ca3Co4O9+δ was about 933 K, which is lower than that of the conventional citric acid method. The resistivities, the Seebeck coefficients and the thermal conductivities of the samples were measured from room temperature to 973 K. The Seebeck coefficients and the resistivities of the doped samples were remarkably enhanced due to the decrease of the carrier concentration, whereas the thermal conductivities of them were decreased due to the impurity scattering effect. The maximal ZT value of 0.26 was obtained at 973 K for Ca2.7 Gd0.15 Y0.15Co4O9+δ. The Ca3-x-yGdxYyCo4O9+δ precursor powders were synthesized by the polyacrylamide gel method. The powders were sintered by the spark plasma sintering (SPS). The DTA analysis showed that the synthesis temperature of Ca3Co4O9+δ was about 933 K, which is lower than that of the conventional citric acid method. The resistivities, the Seebeck coefficients and the thermal conductivities of the samples were measured from room temperature to 973 K. The Seebeck coefficients and the resistivities of the doped samples were remarkably enhanced due to the decrease of the carrier concentration, whereas the thermal conductivities of them were decreased due to the impurity scattering effect. The maximal ZT value of 0.26 was obtained at 973 K for Ca2.7 Gd0.15 Y0.15Co4O9+δ.

Emergence and Persistence of NS5A and NS3 Resistance-Associated Substitutions in HCV Genotype 1b Patients Treated with Daclatasvir and Asunaprevir

( F. Mcphee ),( D. Hernandez ),( N. Zhou ),( F. Yu ),( B. Kienzle ),( Y. Zhao ),( M. Linaberry ),( S. Noviello ),( M. L. Yu ),( S. H. Ahn ),( Y. Karino ),( K. Chayama ),( H. Kumada ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: A pooled analysis of emergent RAS was performed in HCV genotype (GT-)1b-infected patients receiving daclatasvir and asunaprevir (DCV+ASV) and the persistence of DCV- and ASV-resistant substitutions through ≥post-treatment Week (PTWK)192 was assessed to understand the RAS profile and help guide potential retreatment options. Methods: HCV GT-1b-infected patients without a sustained virologic response (SVR) and with HCV RNA ≥1000 IU/mL on or after DCV+ASV treatment were included from 5 Phase 2 and 3 studies. Baseline and post-baseline plasma samples were sequenced at a sensitivity cut-off ł20%. To determine the persistence of emergent RAS, samples at the end of study (up to PTWK48) and/or from a 3-year long-term follow-up rollover study were sequenced (sensitivity cut-off ≥20%, and ≥1% for select samples). Results: 152 DCV+ASV-treated patients without SVR met the resistance testing criteria: 89% (136/152) had NS5A and 95% (145/152) had NS3 sequences at both baseline and virologic failure (VF). NS5A and NS3 RAS emerged in 99% (134/136) and 89% (129/145), respectively, at VF (Table). Overall, 93% (142/152) of patients with VF had both NS5A and NS3 sequence data at failure, of which 77% (109/142) had RAS at L31, Y93 and D168. Emergent NS5A RAS persisted at PTWK96 (92%;24/26) and ≥PTWK192 (100;7/7compared with 22% (6/27) and 14% (1/7), respectively, for emergent NS3 RAS. Replacement of emergent NS5A and NS3 RAS observed at VF occurred in 8% (2/26) of NS5A and 74% (17/23) of NS3 sequences at PTWK96 and in 0% (0/7) of NS5A and 86% (6/7) of NS3 sequences at ≥PTWK192. Conclusions: NS5A and NS3 RAS emerged in most patients treated with DCV+ASV who experienced VF, and NS5A RAS persisted post-treatment. Therapy options for DCV+ASV treatment failures may depend on the timing of retreatment: an NS3 inhibitor-containing regimen may be possible if NS3 RAS are no longer observed, while regimens not impacted by the NS5A-L31+Y93 and NS3-D168 RAS combination would offer an immediate alternative.

Separation dynamics of hydrogen isotope gas in mesoporous and microporous adsorbent beds at 77 K: SBA-15 and zeolites 5A, Y, 10X

Chu, X.Z.,Cheng, Z.P.,Xiang, X.X.,Xu, J.M.,Zhao, Y.J.,Zhang, W.G.,Lv, J.S.,Zhou, Y.P.,Zhou, L.,Moon, D.K.,Lee, C.H. Pergamon Press ; Elsevier Science Ltd 2014 International journal of hydrogen energy Vol.39 No.9

The separation of a hydrogen isotope mixture on porous materials was studied using equilibrium and breakthrough experiments. The adsorption equilibria of H<SUB>2</SUB> and D<SUB>2</SUB> on SBA-15 with mesopores and molecular sieves 5A, Y, and 10X with micropores were measured at 77 K using the volumetric method. The breakthrough experiments of a H<SUB>2</SUB> and D<SUB>2</SUB> mixture in each adsorbent bed were carried out at various conditions of flow rate and pressure. The equilibrium ratio of D<SUB>2</SUB> to H<SUB>2</SUB> on mesoporous molecular sieves was larger than the ratio on microporous molecular sieves (SBA-15 > 10X > Y > 5A), but the difference among the adsorbents decreased with increases in pressure. On the other hand, the order of breakthrough separation factor showed the opposite result (SBA-15 < 10X < Y < 5A). The breakthrough separation factors for zeolite 10X was approximately equal to the equilibrium ratio of D<SUB>2</SUB> to H<SUB>2</SUB> at the corresponding partial pressures, whereas zeolites 5A and Y showed higher breakthrough separation factors than their equilibrium ratios. In SBA-15, the separation factors from breakthrough results were even smaller than the corresponding equilibrium ratio. In the microporous adsorbent with a limited pore size (zeolite 5A in the study), the diffusion mechanism contributed to the separation of hydrogen isotope gases as one of key factors.

Coagulation characteristics of titanium (Ti) salt coagulant compared with aluminum (Al) and iron (Fe) salts

Zhao, Y.X.,Gao, B.Y.,Shon, H.K.,Cao, B.C.,Kim, J.-H. Elsevier 2011 Journal of hazardous materials Vol.185 No.2

<P><B>Abstract</B></P><P>In this study, the performance of titanium tetrachloride (TiCl<SUB>4</SUB>) coagulation and flocculation is compared with commonly used coagulants such as aluminum sulfate (Al<SUB>2</SUB>(SO<SUB>4</SUB>)<SUB>3</SUB>), polyaluminum chloride (PACl), iron chloride (FeCl<SUB>3</SUB>), and polyferric sulfate (PFS) in terms of water quality parameters and floc properties. TiCl<SUB>4</SUB> flocculation achieved higher removal of UV<SUB>254</SUB> (98%), dissolved organic carbon (DOC) (84%) and turbidity (93%) than other conventional coagulants. Charge neutralization and physical entrapment of colloids within coagulant precipitates and adsorption, seemed to play a significant role during TiCl<SUB>4</SUB> flocculation, while the main mechanism for conventional coagulants was bridge-aggregation and adsorption. The aggregated flocs after TiCl<SUB>4</SUB> flocculation showed the fastest growth rate compared to the other coagulants, with the largest floc size (801μm) occurring within 8min. The floc strength factor of PACl, Al<SUB>2</SUB>(SO<SUB>4</SUB>)<SUB>3</SUB>, PFS, FeCl<SUB>3</SUB> and TiCl<SUB>4</SUB> was 34, 30, 29, 26 and 29, respectively, while the floc recovery factor of the TiCl<SUB>4</SUB> coagulant was the lowest. Based on the results of the above study, it is concluded that the TiCl<SUB>4</SUB> flocculation can reduce the hydraulic retention time of slow and rapid mixing, however, careful handling of sludge is required due to the low recoverability of the aggregated floc.</P>

Oxidatively Stable Nanoporous Silicon Photocathodes with Enhanced Onset Voltage for Photoelectrochemical Proton Reduction

Zhao, Y.,Anderson, N. C.,Zhu, K.,Aguiar, J. A.,Seabold, J. A.,Lagemaat, J. van de,Branz, H. M.,Neale, N. R.,Oh, J. American Chemical Society 2015 NANO LETTERS Vol.15 No.4

<P>Stable and high-performance nanoporous “black silicon” photoelectrodes with electrolessly deposited Pt nanoparticle (NP) catalysts are made with two metal-assisted etching steps. Doubly etched samples exhibit an ∼300 mV positive shift in photocurrent onset for photoelectrochemical proton reduction compared to oxide-free planar Si with identical catalysts. We find that the photocurrent onset voltage of black Si photocathodes prepared from single-crystal planar Si wafers by an Ag-assisted etching process increases in oxidative environments (e.g., aqueous electrolyte) owing to a positive flat-band potential shift caused by surface oxidation. However, within 24 h, the surface oxide layer becomes a kinetic barrier to interfacial charge transfer that inhibits proton reduction. To mitigate this issue, we developed a novel second Pt-assisted etch process that buries the Pt NPs deep into the nanoporous Si surface. This second etch shifts the onset voltage positively, from +0.25 V to +0.4 V versus reversible hydrogen electrode, and reduces the charge-transfer resistance with no performance decrease seen for at least two months. PEC performance was stable owing to Pt NP catalysts that were buried deeply in the photoelectrode by the second etch, below a thick surface layer comprised primarily of amorphous SiO<SUB>2</SUB> along with some degree of remaining crystalline Si as observed by scanning and transmission electron micrographs. Electrochemical impedance studies reveal that the second etch leads to a considerably smaller interfacial charge-transfer resistance than samples without the additional etch, suggesting that burying the Pt NPs improves the interfacial contact to the crystalline silicon surface.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2015/nalefd.2015.15.issue-4/acs.nanolett.5b00086/production/images/medium/nl-2015-00086g_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl5b00086'>ACS Electronic Supporting Info</A></P>

ENHANCED FUZZY SLIDING MODE CONTROLLER FOR LAUNCH CONTROL OF AMT VEHICLE USING A BRUSHLESS DC MOTOR DRIVE

Zhao, Y.S.,Chen, L.P.,Zhang, Y.Q.,Yang, J. The Korean Society of Automotive Engineers 2007 International journal of automotive technology Vol.8 No.3

Due to the clutch's non-linear dynamics, time-delays, external disturbance and parameter uncertainty, the automated clutch is difficult to control precisely during the launch process or automatic mechanical transmission (AMT) vehicles. In this paper, an enhanced fuzzy sliding mode controller (EFSMC) is proposed to control the automated clutch. The sliding and global stability conditions are formulated and analyzed in terms of the Lyapunov full quadratic form. The chattering phenomenon is handled by using a saturation function to replace the pure sign function and fuzzy logic adaptation system in the control law. To meet the real-time requirement of the automated clutch, the region-wise linear technology s adopted to reduce the fuzzy rules of the EFSMC. The simulation results have shown hat the proposed controller can achieve a higher performance with minimum reaching time and smooth control actions. In addition, our data also show that the controller is effective and robust to the parametric variation and external disturbance.

Dependence of the properties of hydrothermally grown ZnO on precursor concentration

Zhao, X.,Lee, J.Y.,Kim, C.-R.,Heo, J.,Shin, C.M.,Leem, J.-Y.,Ryu, H.,Chang, J.-H.,Lee, H.C.,Jung, W.-G.,Son, C.-S.,Shin, B.C.,Lee, W.-J.,Tan, S.T.,Zhao, J.,Sun, X. North-Holland 2009 Physica E, Low-dimensional systems & nanostructure Vol.41 No.8

This study evaluated the effects of precursor concentration ranging from 0.06 to 1.5M on the properties of hydrothermally grown ZnO on annealed ZnO buffered Si substrates. At relatively low concentrations (no more than 0.5M), well-aligned ZnO arrays were grown on ZnO/Si(100) due to heterogeneous nucleation. As the concentration was increased to 1.0M, the morphologies changed to randomly accumulated particles as a result of homogeneous nucleation. The crystal and optical properties of the materials were investigated by X-ray diffractometer (XRD) and photoluminescence (PL) measurement, respectively. It was found that the best crystal and optical properties were obtained with concentrations of 0.5 and 0.3M, respectively. These properties were observed to degrade when the concentration was raised to more than 1.0M.

Semiconducting behavior of bilayer graphene synthesized by plasma-enhanced chemical vapor deposition and its application in field effect transistors

Zhao, Y.,Soo Park, C.,Dong Fei, W.,Jin Lee, C. North-Holland 2014 Materials letters Vol.136 No.-

We demonstrated the generation of a bandgap in the bilayer graphene synthesized by plasma-enhanced chemical vapor deposition. By adjusting the growth time, the defect density and nano-crystallite size of bilayer graphene were easily controlled, affecting the bandgap of bilayer graphene and the field effect mobility of bilayer graphene field effect transistor (FET). The defect density increased with increasing growth time, whereas the nano-crystallite size decreased. The semiconducting behavior of bilayer graphene was observed by measuring the temperature-dependent conductivity. Defects generated by plasma radiation induce broken symmetry in graphene, thus opening a bandgap. The bandgap energies in the bilayer graphene are 90, 156, and 187meV for growth times of 5, 10, and 30min, respectively. The back-gate bilayer graphene FET presented the p-type semiconducting behavior and the field effect mobility of approximately 1000cm<SUP>2</SUP>V<SUP>-1</SUP>s<SUP>-1</SUP> when the bandgap energy was 156meV.

The effect of second coagulant dose on the regrowth of flocs formed by charge neutralization and sweep coagulation using titanium tetrachloride (TiCl₄4)

Zhao, Y.X.,Gao, B.Y.,Shon, H.K.,Wang, Y.,Kim, J.H.,Yue, Q.Y. Elsevier Scientific Pub. Co 2011 Journal of hazardous materials Vol.198 No.-

Characteristics of flocs formed by charge neutralization and sweep coagulation using titanium tetrachloride (TiCl<SUB>4</SUB>) were investigated with humic acid-kaolin suspension by continuous optical monitoring. This paper focused on the regrowth ability of broken flocs after addition of second TiCl<SUB>4</SUB> dose. Variation of floc size and the fractal dimension of flocs versus second TiCl<SUB>4</SUB> dose after regrowth were investigated. Second TiCl<SUB>4</SUB> dose was added during the floc breakage period, and addition time of second TiCl<SUB>4</SUB> dose was also investigated. The results showed that, when coagulated by charge neutralization at pH 6, an appropriate second TiCl<SUB>4</SUB> dose improved regrowth ability of broken flocs at low initial TiCl<SUB>4</SUB> doses. While for high initial TiCl<SUB>4</SUB> doses, second TiCl<SUB>4</SUB> dose lowered floc re-growth ability. When coagulated by sweep coagulation at pH 10, second TiCl<SUB>4</SUB> dose made regrown flocs larger than those without second TiCl<SUB>4</SUB> dose. Floc structure analysis showed that it was determined by not only the fractal dimension of flocs, but also the chemical characteristics of floc surface. Addition time of second TiCl<SUB>4</SUB> dose had a great effect on floc regrowth ability, suggesting that the broken flocs had better regrowth when second TiCl<SUB>4</SUB> dose was added at the end of the breakage period.