Generation of hyperchaos from the Chen–Lee system via sinusoidal perturbation

A system with more than one positive Lyapunov exponent can be classified as a hyperchaotic system. In this study, a sinusoidal perturbation was designed for generating hyperchaos from the Chen–Lee chaotic system. The hyperchaos was identified by the existence of two positive Lyapunov exponents and bifurcation diagrams. The system is hyperchaotic in several different regions of the parameters c, ε, and ω. It was found that this method not only can enhance or suppress chaotic behavior, but also induces chaos in non-chaotic parameter ranges. In addition, two interesting dynamical behaviors, Hopf bifurcation and intermittency, were also found in this study.     

Electric field effect on the optically-pumped far-infrared laser

This study investigates the effects of the electric field on the optically-pumped far-infrared (OPFIR) laser. The main mechanisms responsible for the change of the laser output power due to the electric field are considered to be the non-linear Hanle effect (NLHE) and Stark splitting. However, both the rate-equation calculation and the experiments with the circular hollow Stark waveguide OPFIR laser show that the conventional NLHE provides a relatively limited power increase via enhanced absorption. Significant power enhancement is observed in the rectangular waveguide only when both the absorption and emission processes are ΔM=±1 transitions, where the classical Hanle effect (CHE) is considered to be applicable. By including constructive interference, the power increase due to the CHE is calculated for the parallel and orthogonal lines. Experimental results from the rectangular waveguide OPFIR laser show good agreement with the new calculation taking into account the classical Hanle and Stark splitting effects.     

Anionic amphiphilic dendrimers as antibacterial agents

An anionic amphiphilic dendrimer is reported that possesses increased cytotoxicological potency against prokaryotic cells compared to eukaryotic cells. The half-maximal effective concentration (EC50) for the dendrimer against Bacillus subtilis, a Gram-positive bacterial strain, was measured to be 4.1 x 10(-5) M, while that against human umbilical vein endothelial cells (HUVEC) was more than 36x greater at a value of 1.5 x 10(-3) M. EC50 ratios for two commercial amphiphiles, sodium dodecyl sulfate (SDS) and Triton X-100, in addition to a similar synthesized dendritic structure were at most only 3.8x greater. Furthermore, the observed EC50 values appear to be correlated to the critical aggregation constant (CAC) in solution suggesting a mechanism of action for these anionic amphiphilic dendrimers related to their supramolecular structures.     

SIRT1 promotes DNA repair activity and deacetylation of Ku70

Human SIRT1 controls various physiological responses including cell fate, stress, and aging, through deacetylation of its specific substrate protein. In processing DNA damage signaling, SIRT1 attenuates a cellular apoptotic response by deacetylation of p53 tumor suppressor. The present study shows that, upon exposure to radiation, SIRT1 could enhance DNA repair capacity and deacetylation of repair protein Ku70. Ectopically over-expressed SIRT1 resulted in the increase of repair of DNA strand breakages produced by radiation. On the other hand, repression of endogenous SIRT1 expression by SIRT1 siRNA led to the decrease of this repair activity, indicating that SIRT1 can regulate DNA repair capacity of cells with DNA strand breaks. In addition, we found that SIRT1 physically complexed with repair protein Ku70, leading to subsequent deacetylation. The dominant-negative SIRT1, a catalytically inactive form, did not induce deacetylation of Ku70 protein as well as increase of DNA repair capacity. These observations suggest that SIRT1 modulates DNA repair activity, which could be regulated by the acetylation status of repair protein Ku70 following DNA damage.     

柔性有源OLED显示器制造几点技术方面的考虑

AMOLED在柔性显示领域前途似锦。LG显示展示了一款全彩4in柔性AMOLED样机,衬底为80μm厚的不锈钢薄片,曲率达到5cm弯曲半径。本文就此项柔性显示技术所面临的挑战进行了探讨．包括柔性衬底衬底的传送、如何获得特性稳定可靠的TFT以使OLED的亮度和一致性适用于此项技术的商业化推广。     

Harmonic broadcasting for video-on-demand service

Using conventional broadcasting, if we want to support a 120-minute popular movie every 10 minutes, we need 12 video channels. Assuming the set-top box at the client end can buffer portions of the playing video on a disk, pyramid broadcasting schemes can reduce the bandwidth requirements to 5.7 channels. We present a new scheme which only needs 3.2 channels. For a movie with length D minutes, if we want to reduce the viewer waiting time to D/N minutes, we only need to allocate H(N) video channels to broadcast the movie periodically, where H(N) is the harmonic number of N, H(N)=1+1/2+…+1/N. In order to support video-on-demand service for a popular movie, the new scheme greatly reduces the bandwidth requirements     

Polybenzimidazoles for High Temperature Fuel Cell Applications

Summary: Fuel cells were designed for high temperature operations. Poly[2,2′‐(m‐phenylene)‐5,5′‐bibenzimidazole] (PBI) was synthesized in a solution of P₂O₅, CH₃SO₃H, and CF₃SO₃H. The PBI was dissolved in a mixture of CF₃CO₂H and H₃PO₄ and the solution was used for the preparation of Pt catalyst slurry for membrane electrode assembly. The single cell showed a current density of 280 mA · cm⁻² at a cell voltage of 0.5 V with feeds of H₂ and O₂ at 160 °C and without external humidification.

     

Three New Clerodane Diterpenoids from the Bulbils of Dioscorea bulbifera L. var. sativa

From the bulbils of Dioscorea bulbifera L. var. sativa, three new clerodane diterpenoids, bafoudiosbulbin C (=methyl (2β,8α,12S)‐17‐oxo‐2,19 : 8,19 : 12,17 : 15,16‐tetraepoxycleroda‐3,13(16), 14‐triene‐18‐carboxylate; 1 ), bafoudiosbulbin D (=methyl (2β,6β,12R)‐17,19‐dioxo‐2,19 : 6,17 : 8,12 : 15,16‐tetraepoxycleroda‐13(16),14‐diene‐18‐carboxylate; 2 ), and bafoudiosbulbin E (=methyl (2β,3α,4α,6β,12R)‐17,19‐dioxo‐2,19 : 3,4 : 6,17 : 8,12 : 15,16‐pentaepoxycleroda‐13(16),14‐diene‐18‐carboxylate; 3 ) were isolated, together with the known compounds bafoudiosbulbins A and B, 3‐O‐β‐D ‐glucopyranosyl‐β‐sitosterol, and 6′‐stearoyl‐3‐O‐β‐D ‐glucopyranosyl‐β‐sitosterol. Their structures were established by high‐field NMR techniques (¹H,¹H‐COSY, ¹³C‐DEPT, HSQC, HMBC, and NOESY), MS analyses, as well as by comparison of their spectral data with those of related compounds.     

Synthesis of Poly(2,5‐benzimidazole) for Use as a Fuel‐Cell Membrane

Summary: Poly(2,5‐benzimidazole) (ABPBI) was synthesized in a novel polymerization medium containing CH₃SO₃H and P₂O₅. 3,4‐Diaminobenzoic acid, a monomer for ABPBI, is soluble in the medium and the polymerization was therefore performed in a homogeneous state. It produced polymer fibers, thus simplifying the work‐up process. The membrane was cast directly from the polymerization mixture. Proton conductivities of the ABPBI membranes ranged from 0.02 to 0.06 S · cm⁻¹ above 100 °C, without humidification, and the tensile strength of the membrane was approximately 100 MPa.

Synthesis of ABPBI in a medium containing methanesulfonic acid and P₂O₅.     

Polyethylenimine‐assisted Synthesis of Au Nanoparticles for Efficient Syngas Production

The ability to capture, store, and use CO₂ is important for remediating greenhouse‐gas emissions and combatting global warming. Herein, Au nanoparticles (Au‐NPs) are synthesized for effective electrochemical CO₂ reduction and syngas production, using polyethylenimine (PEI) as a ligand molecule. The PEI‐assisted synthesis provides uniformly sized 3‐nm Au NPs, whereas larger irregularly shaped NPs are formed in the absence of PEI in the synthesis solution. The Au‐NPs synthesized with PEI (PEI?Au/C, average PEI Mw=2000) exhibit improved CO₂ reduction activities compared to Au‐NPs formed in the absence of PEI (bare Au NPs/C). PEI?Au/C displays a 34 % higher activity toward CO₂ reduction than bare Au NPs/C; for example, PEI?Au/C exhibits a CO partial current density (j_CO) of 28.6 mA cm^?2 at ?1.13 V_RHE, while the value for bare Au NPs/C is 21.7 mA cm^?2; the enhanced j_CO is mainly due to the larger surface area of PEI?Au/C. Furthermore, the PEI?Au/C electrode exhibits stable performance over 64 h, with an hourly current degradation rate of 0.25 %. The developed PEI?Au/C is employed in a CO₂‐reduction device coupled with an IrO₂ water‐oxidation catalyst and a proton‐conducting perfluorinated membrane to form a PEI?Au/C|Nafion|IrO₂ membrane‐electrode assembly. The device using PEI?Au/C as the CO₂‐reduction catalyst exhibits a j_CO of 4.47 mA/cm² at 2.0 V_cell. Importantly, the resulted PEI?Au/C is appropriate for efficient syngas production with a CO ratio of around 30–50 %.