The role of co-adsorbed O2 on the catalytic reduction of NO with C2H5OH on the surface of Pt(3 3 2)

The influence of pre-dosed O₂ on the catalytic reduction of NO with ¹³C₂H₅OH on the surface of stepped Pt(3 3 2) was investigated using Fourier transform infra red reflection-absorption spectroscopy (FTIR-RAS) and thermal desorption spectroscopy (TDS). We show that the oxidation of ¹³C₂H₅OH with O₂ is a very effective reaction, occurring at 150 K and giving rise to acetate. The presence of NO does not lead to any evident oxidation of ¹³C₂H₅OH irrespective of the annealing temperature. For the case of O₂ + ¹³C₂H₅OH + NO co-adlayers, oxidation of ¹³C₂H₅OH also takes place at 150 K. However, no new surface species that are supposed to be an intermediate for the production of N₂ are detected.The influence of O₂ on the production and desorption of N₂ is intimately related to both O₂ and ¹³C₂H₅OH coverage. The presence of pre-dosed O₂ does not greatly promote N₂ desorption. In fact, N₂ desorption is suppressed quantitatively with increasing O₂ coverage, after which unreacted, or left-over O atoms appear and remain on steps. It is concluded that the presence of pre-dosed O₂ does not play a role of activating reactants in the catalytic reduction of NO with ¹³C₂H₅OH on the surface of Pt(3 3 2).     

La2O3对Yb:Y2O3透明陶瓷光谱性能的影响

研究了La2O3对Yb:Y2O3透明陶瓷光谱性能的影响,添加适量La2O3以后,Yb:Y2O3透明陶瓷的吸收峰和发射峰的位置不变,但由于La3+的离子半径大于Y3+的离子半径,在Y2O3中引入La3+离子后,导致Y2O3晶格常数变大,晶场强度变弱,同时降低了Y2O3晶体的有序度,致使发射峰强度有所下降,发射截面变小.过量的La2O3(x=0.16)造成Yb3+激活离子发射强度明显下降;其荧光寿命在添加La2O3后总体增大45%-60%.     

Effect of calcium malonate on the formation of β crystalline form in isotactic poly(propylene)

Calcium malonate (Camt) is used to induce the β crystalline form in isotactic polypropylene (iPP) for the first time. The relative content of the β crystalline form (K value) increases markedly with the addition of Camt and attains the maximum value of 73.48% at 0.40% Camt. The amounts of bright and colorful β spherulites increase and the spherulitic sizes decrease with the increase in Camt contents. The tensile strength and the Izod notched impact strength of the nucleated iPP samples increase with the addition of Camt; in particular, the latter almost doubles at 0.40% Camt compared to that of the blank iPP sample. The β nucleation mechanism of Camt is analyzed by the dimensional lattice match criterion. Copyright © 2008 John Wiley & Sons, Ltd.     

Effect of β-Nucleating Agent on the Crystallization,Mechanical Properties,and Heat Resistance of Injection-Molded Isotactic Polypropylene

Injection-molded β-isotactic polypropylene (β-iPP) was prepared with a commercial β-nucleating agent (NT-A). The effect of NT-A on the crystallization, mechanical properties, and heat resistance of β-iPP was investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), polarized light microscopy (PLM), and mechanical and heat deflection tests. DSC and WAXD analysis showed that the content of β-crystals in the nucleated iPP was higher than that of pure iPP, and the content of β-crystals of the core was higher than that of the skin. PLM observations showed that injection-molded iPP had an obvious skin-core structure. NT-A induced abundant β-crystals and resulted in small spherulites which improved the Izod notched impact strength. When the content of NT-A was 0.075wt%, the Izod notched impact strength reached a maximum, 2.6 times more than that of pure iPP. The heat distortion temperature was also improved by NT-A.     

Multiple modulator-induced syntheses,crystal structures,and luminescent properties on hippuric acid and bovine serum albumin of Ln(III) complexes with 2,2′-oxybis(benzoic acid)

Six new coordination complexes, Ln₂(2,2′-oba)₂(phen)₂(ox)(H₂O)₂ (Ln = Eu 1, Tb 2), Ln₄(2,2′-oba)₆(phen)₂ (Ln = Eu 3, Tb 4), Eu₄(2,2′-oba)₆(phen)₂(H₂O) (5), and K[Eu(2,2′-oba)₂(phen)₂] (6) [2,2′-H₂oba = 2,2′-oxybis(benzoic acid), phen = 1,10-phenanthroline, H₂ox = oxalic acid] were synthesized by hydrothermal reactions with the same compound molar ratios but different modulatory reagents (MRs). Complexes 1–5 have different 1-D chain structures and 6 shows a mononuclear structure. These complexes form diverse 3-D supramolecular networks through hydrogen bonds. The interaction between these complexes and hippuric acid (HA) or bovine serum albumin (BSA) was investigated by fluorescence spectral analysis. Interestingly, the hippuric acid could quench the luminescence of these complexes while the fluorescence of BSA could be quenched by these complexes. Results suggested that the complexes may be potential luminescent testing reagents for HA or BSA by significant fluorescence quenching of Ln³⁺ or BSA, respectively, through a static and dynamic quenching process.     

An Alternating Polymer of Two Building Blocks Based on B←N Unit:Non-fullerene Acceptor for Organic Photovoltaics

B←N coordination bond can be used to develop polymer electron acceptors for efficient all-polymer solar cells(all-PSCs). Here, we report a new alternating conjugated polymer containing two building blocks based on B←N unit. The polymer exhibits strong light absorption in the visible range, low-lying LUMO/HOMO energy levels and moderate electron mobility. The resulting all-PSC devices exhibit power conversion efficiencies of 1.50%–2.47%.