Design of Double Cassegrain reflective mirrors for optical system of IR cameras

IR optical systems such as Petzval doublet refractive lenses or Cassegrain reflective mirrors are either expensive or poor in image quality. Taking advantage of the low cost of reflective mirrors, here we present an optical design of Double Cassegrain reflective mirrors consisting of two sets of Cassegrain reflectors facing each other symmetrically. This symmetry also cancels many aberrations besides the chromatic aberration-free nature of reflective mirrors. Design results show that this system is better than Cassegrain reflectors in aberration correction and image resolution, but cheaper than Petzval doublet refractive lenses systems in price. IR cameras with this optical system could be widely used for body temperature measurement and security check.     

Cellular Uptake of a Polypyridyl Ruthenium Complex Revealed Using a Fluorescent Rhodamine‐modified Ruthenium Complex

A fluorescent polypyridyl ruthenium complex was successfully prepared using an amide bond linkage to link two rhodamine moieties through bipyridine groups. Although photo‐induced electron transfer (PET) quenched the fluorescent intensity, the quantum yield of the rhodamine‐modified Ru(II) complex was 0.17 in water, sufficient for observing the fluorophore behaviour in biological systems. The rhodaminemodified Ru(II) complex was found to inhibit the bacterial growth of E. coli. In vitro fluorescence images of human hepatoma cells (SK‐Hep1) showed that a fluorescent polypyridyl ruthenium complex not only supported the above observation but also preferably accumulated in the cytoplasmic region inside the cell. These observations suggest that in addition to strong Ru–DNA interactions, Ru‐protein interactions in the cytoplasmic regions are strong and are therefore important to the development of metallopharmaceuticals.     

Thermal and spectral stability of electroluminescent hyperbranched copolymers containing tetraphenylthiophene‐quinoline‐triphenylamine moieties

Fluorescent hyperbranched copolymers (HB‐x, x = 1–4) with inherent tetraphenylthiophene, triphenylamine (TPA) and quinoline (Qu) moieties were prepared to study the influence of the TPA branching point on the thermal and the spectral stability. All the HB‐x copolymers exhibited high glass transition temperatures (T_gs = 245–315 °C) with the detected values increasing with the increasing branching TPA content in the HB‐x. The solid HB‐x films possess high emission efficiency with the resulting quantum yields (?_Fs) in the ranges of 0.72–0.74. More importantly, the HB‐x copolymers and the derived light‐emitting devices exhibit high photoluminescence (PL) and electroluminescence (EL) stability towards thermal annealing at temperatures higher than 200 °C. After annealing at 200 °C (or 300 °C), no change was observed in the respective PL and EL spectra of HB‐1 (or HB‐4) copolymers. The spectral stability was found to correlate with T_g and with the highest branching density, HB‐4 copolymer possesses the highest thermal stability among all HB‐xs and show no EL spectral change after annealing at 300 °C for 4 h. The results indicate that all the branched HB‐x copolymers are promising candidates for the polymer light‐emitting diodes due to their high quantum yield and spectral stability. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

A study of the switching mechanism and electrode material of?fully CMOS compatible tungsten oxide ReRAM

Tungsten oxide (WO _X ) resistive memory (ReRAM), a two-terminal CMOS compatible nonvolatile memory, has shown promise to surpass the existing flash memory in terms of scalability, switching speed, and potential for 3D stacking. The memory layer, WO _X , can be easily fabricated by down-stream plasma oxidation (DSPO) or rapid thermal oxidation (RTO) of W plugs universally used in CMOS circuits. Results of conductive AFM (C-AFM) experiment suggest the switching mechanism is dominated by the REDOX (Reduction-oxidation) reaction??the creation of conducting filaments leads to a low resistance state and the rupturing of the filaments results in a high resistance state. Our experimental results show that the reactions happen at the TE/WO _X interface. With this understanding in mind, we proposed two approaches to boost the memory performance: (i) using DSPO to treat the RTO WO _X surface and (ii) using Pt TE, which forms a Schottky barrier with WO _X . Both approaches, especially the latter, significantly reduce the forming current and enlarge the memory window.     

Effect of immobilization of polysaccharides on the biocompatibility of poly(butyleneadipate‐co‐terephthalate) films

Aiming to improve the hydrophilicity, antibacterial activity, cytocompatibility, and hemocompatibility of poly(butyleneadipate‐co‐terephthalate) (PBAT) films, PBAT films were treated with ozone, grafted with chitosan (CS), and followed by covalent immobilization of either heparin (HEP) or hyaluronic acid (HA). The surface graft density of modified PBAT films was detected by X‐ray photoelectron spectroscopy (XPS) and dyeing. The surface roughness of PBAT films was measured using an atomic force microscope (AFM). After immobilizing CS, PBAT films acquired antibacterial activity against Staphylococcus aureus and Escherichia coli. The adsorption of human serum albumin (HSA) and human plasma fibrinogen (HPF) on PBAT–CS–HEP and PBAT–CS–HA films was lower compared to that of native PBAT. Moreover, HEP immobilization could effectively reduce platelet adhesion and prolong the blood coagulation time, thereby improving the blood compatibility of PBAT. In addition, the growth of L929 fibroblasts was improved for HEP or HA immobilized PBAT, suggesting this surface modification was non‐cytotoxic. Furthermore, PBAT–CS–HEP and PBAT–CS–HA exhibited higher cell proliferation than native PBAT. Copyright © 2009 John Wiley & Sons, Ltd.     

Polymeric nanocomposite comprising gold nanoparticles and bilaterally sulfur‐functionalized polystyrene

Anionic polymerization technique has been utilized to synthesize a bilaterally sulfur‐functionalized polystyrene, SCH3‐polystyrene‐SH. The synthesis scheme consists of (1) initiation of 4‐vinylbenzylmethyl sulfide with sec‐butyllithium to form a living sulfur‐containing initiator, (2) polymerization of styrene, and (3) termination of growing polystyrene chain with ethylene sulfide. The resulting bilaterally sulfur‐functionalized polystyrene is used to make polystyrene/gold nanoparticles (AuNPs) nanocomposite with AuNPs formed in situ in polymer solution through reduction of AuClO₄. The effects of the polymer/Au molar ratio as well as the molecular weight of polymer on the size and dispersion of formed AuNPs have been studied, and the superiority of bilaterally functionalized polymer to unilaterally functionalized polymer has been demonstrated. The polystyrene/AuNPs composite has been characterized by GPC, ¹H‐NMR, ¹³C‐NMR, EDS, TEM, UV‐Vis, and DSC. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1268–1277