Zr离子掺杂TiO2可见光催化剂光催化活性的研究

本文采用溶胶-凝胶法制备了Zr离子掺杂TiO₂光催化剂。光催化降解对氯苯酚实验表明,Zr离子掺杂浓度为10%时活性最高,其紫外光、可见光催化活性分别是纯TiO₂的1.5倍和4倍。利用XRD、Raman、XPS、UV-Vis DRS、PL等技术对样品进行了表征,结果表明：Zr离子以取代式掺杂方式进入TiO₂晶格,在TiO₂导带下方形成掺杂能级,增强了可见光响应,促进了光生载流子的分离,此外Zr离子掺杂在催化剂表面引入大量表面缺陷,增加了表面羟基物种,从而使得Zr离子掺杂TiO₂光催化剂的紫外、可见光催化活性显著提高。     

The morphological effects upon enzymatic degradation of poly(butylene succinate-co-butylene terephthalate)s (PBST)

In this work, the enzymatic degradation of poly(butylene succinate-co-butylene terephthalate) (PBST) copolyesters was studied using the lipase from Pseudomonas (Lipase PS^®). The biodegradation behavior was found to strongly depend on the overall impacts of several important factors as the BT comonomer structure and molar content, thermal characteristics, morphology, the enzyme-substrate, and so forth. Further, the biodegraded residual film samples were allowed to be analyzed by means of gel permeation chromatography (GPC), proton nuclear magnetic resonance (¹H NMR), differential scanning calorimeter (DSC), small angle X-ray scattering (SAXS), and scanning electron microscope (SEM). On the experimental evidences, an exo-type mechanism of enzymatic chain hydrolysis preferentially occurring in the amorphous region was suggested for the PBST film samples.     

Soluble porphyrin-bisindolylmaleimides dyad and pentamer as saturated red luminescent materials

Novel soluble porphyrin-bisindolylmaleimides dyad and pentamer have been prepared conveniently by coupling of amino-porphyrins and bisindolylmaleic anhydride. The bisindolylmaleimide groups function as the antenna to efficiently enhance the intramolecular energy transfer to the porphyrin core. These compounds may serve as good candidates of red-light emitting materials for organic light-emitting diodes.     

Spectroscopic studies of dehydrogenation of ammonia borane in carbon cryogel

Ammonia borane (AB) is of great interest for storing hydrogen, an important issue in the growing field of hydrogen technology. The reaction pathways leading to the thermal decomposition of solid-state AB incorporated in carbon cryogels (CC) have been studied by spectroscopic methods. The time-dependent thermal decomposition was followed by in situ 11B nuclear magnetic resonance (NMR) and showed a significant increase in hydrogen release kinetics for AB in CC compared to neat AB. Both 11B NMR and Fourier transform infrared spectroscopy show a new reaction product, formed in the thermal decomposition of AB in CC scaffold (CC-AB) that is assigned to reactions with surface oxygen groups. The results indicate that incorporation of AB in CC enhances kinetics because of the reactions with residual surface-bound oxygen functional groups. The formation of new products with surface -O-B bonds is consistent with the greater reaction exothermicity observed when hydrogen is released from CC-AB materials. Scanning electron microscopy shows different morphology of AB in CC-AB nanocomposite as compared to neat AB.     

Fluorimetric determination of phytic acid in urine based on replacement reaction

A sensitive fluorimetric method for determination of phytic acid in human urine samples was described. The method was based on a fluorimetric replacement reaction, in which the added phytic acid replaced the Cu²⁺ ion from Cu²⁺-gelatin complex, liberating the fluorescent gelatin molecule. The fluorescence of the solution was accordingly recovered proportionally to the amount of the foreign phytic acid. The excitation wavelength was 273.5 nm and the characteristic emission wavelength was 305.0 nm, respectively. The calibration graph was obtained by plotting the recovered fluorescent intensity at maximum 305.0 nm against the added standard phytic acid, and was divided into two sections. One section was linear over the range of 0.40-2.40 mg L⁻¹ with a linear regression equation of I_f = −0.895 + 15.146c (R² > 0.9993), and the other over the range of 2.40-9.20 mg L⁻¹ with a linear regression equation of I_f = −29.526 + 26.113c (R² > 0.9996), respectively. The relative standard deviation (R.S.D.) at 95% confidence degree for a 2.0 mg L⁻¹ of standard phytic acid within 1 month was less than 1.26% (n = 5), indicating the procedure is reproducible. The detection and the quantification limits of phytic acid were estimated to be 0.23 and 0.40 mg L⁻¹, respectively. The proposed method was applied to the determination of phytic acid in urine samples and the found concentrations of phytic acid in urine were in the range of 0.49-0.75 mg L⁻¹ with recoveries of 96.2-108.8%. Comparison of the obtained results with the reported HPLC was performed, indicating the proposed method was reliable.     

Unusual halogen-bonded complex FBrdelta+...delta+BrF and hydrogen-bonded complex FBrdelta+...delta+HF formed by interactions between two positively charged atoms of different polar molecules

Using ab initio calculations, the authors' predicted for the first time that the halogen-bonded complex FBrdelta+...delta+BrF and hydrogen-bonded complex FBrdelta+...delta+HF formed by the interactions between two positively charged atoms of different polar molecules can be stable in gas phase. It shows that halogen bond or hydrogen bond not only exists between oppositely charged atoms but also between like-charged atoms. That the attraction arising from the special halogen bond or hydrogen bond can exceed the electrostatic repulsion between two contact positively charged atoms stabilizes the complex. Of course, from the point of view of physics they can consider the interactions in FBrdelta+...delta+BrF and FBrdelta+...delta+HF as mainly the sum of the long range molecular interactions, namely, electrostatic, induction, and dispersion with some short-range repulsion. They found that the intermolecular electron correlation contribution representing dispersion interaction plays a crucial role in the stabilities of seemingly repulsive complexes FBrdelta+...delta+BrF and FBrdelta+...delta+HF.     

Singly versus Doubly Reduced Nickel Porphyrins for Proton Reduction: Experimental and Theoretical Evidence for a Homolytic Hydrogen‐Evolution Reaction

A nickel(II) porphyrin Ni‐P (P=porphyrin) bearing four meso‐C₆F₅ groups to improve solubility and activity was used to explore different hydrogen‐evolution‐reaction (HER) mechanisms. Doubly reduced Ni‐P ([ Ni‐P ]^2?) was involved in H₂ production from acetic acid, whereas a singly reduced species ([ Ni‐P ]^?) initiated HER with stronger trifluoroacetic acid (TFA). High activity and stability of Ni‐P were observed in catalysis, with a remarkable i_c/i_p value of 77 with TFA at a scan rate of 100 mV s^?1 and 20 °C. Electrochemical, stopped‐flow, and theoretical studies indicated that a hydride species [H‐ Ni‐P ] is formed by oxidative protonation of [ Ni‐P ]^?. Subsequent rapid bimetallic homolysis to give H₂ and Ni‐P is probably involved in the catalytic cycle. HER cycling through this one‐electron‐reduction and homolysis mechanism has been proposed previously but rarely validated. The present results could thus have broad implications for the design of new exquisite cycles for H₂ generation.     

Dual‐Targeting Nanovesicles for In Situ Intracellular Imaging of and Discrimination between Wild‐type and Mutant p53

p53 is a tumor‐suppressor protein related to the cell cycle and programmed cell apoptosis. Herein, dual‐targeting nanovesicles are designed for in situ imaging of intracellular wild‐type p53 (WTp53) and mutant p53 (MUp53). Nanovesicle‐encapsulated plasmonic gold nanoparticles (AuNPs) were functionalized with consensus DNA duplexes, and a fluorescein isothiocyanate (FITC)‐marked anti‐MUp53 antibody was conjugated to the nanovesicle surface. After entering the cytoplasm, the released AuNPs aggregated through recognition of WTp53 and the double‐stranded DNA. The color changes of AuNPs were observed using dark‐field microscopy, which showed the intracellular WTp53 distribution. The MUp53 location was detected though the immunological recognition between FITC‐labeled anti‐MUp53 and MUp53. Thus, a one‐step incubation method for the in situ imaging of intracellular WTp53 and MUp53 was obtained; this was used to monitor the p53 level under a drug treatment.     

An Alignment Medium for Measuring Residual Dipolar Couplings in Pure DMSO: Liquid Crystals from Graphene Oxide Grafted with Polymer Brushes

Residual dipolar couplings (RDCs) have attracted attention in light of their great impact on the structural elucidation of organic molecules. However, the effectiveness of RDC measurements is limited by the shortage of alignment media compatible with widely used organic solvents, such as DMSO. Herein, we present the first liquid crystal (LC) based alignment medium that is compatible with pure DMSO, thus enabling RDC measurements of polar and intermediate polarity molecules. The liquid crystals were obtained by grafting polymer brushes onto graphene oxide (GO) using free radical polymerization. The resulting new medium offers several advantages, such as absence of background signals, narrow line shapes, and tunable alignment. Importantly, this medium is compatible with π‐conjugated molecules. Moreover, sonication‐induced fragmentation can reduce the size of GO sheets. The resulting anisotropic medium has moderate alignment strength, which is a prerequisite for an accurate RDC measurement.     

A P/N type compounded Cu<Subscript>2</Subscript>O/TiO<Subscript>2</Subscript> photo-catalytic membrane for organic pollutant degradation

A heterojunction thin film consisting of n-type titanium dioxide (TiO₂) and p-type cuprous oxide (Cu₂O) was fabricated on an FTO conducting glass. The TiO₂ films were grown on the FTO glass by sol–gel and spray pyrolysis methods, and Cu₂O was deposited on it via the hydrothermal method. The morphology, crystalline structure, and optical absorption characteristics were studied by scanning electron microscopy, X-ray diffraction, and ultraviolet–visible diffuse reflectance spectrum, respectively. The results show that the surface of the Cu₂O/TiO₂ film was composed of net and large grains, which contributed to a large specific surface area. The crystal phase of the TiO₂ in the Cu₂O/TiO₂ film remained anatase. The crystal phase of the Cu₂O could not be detected as it is found in traces. The Cu₂O/TiO₂ film had a stronger optical absorption ability than the pure TiO₂ film. To investigate catalytic activity, a photocatalytic degradation experiment of the Cu₂O/TiO₂ film was performed in a homemade thin-layer micro-reactor. The photocatalytic degradation of methylene blue increased with increasing amounts of deposited Cu₂O until a maximum limit was reached. The photocatalytic activity might have declined with an increase in Cu₂O content. The metallic oxide has the potential to screen other photocatalysts from the UV source.