Enhancement of Enzymatic Hydrolysis and Klason Lignin Removal of Corn Stover Using Photocatalyst-Assisted Ammonia Pretreatment

Photocatalyst-assisted ammonia pretreatment was explored to improve lignin removal of the lignocellulosic biomass for effective sugar conversion. Corn stover was treated with 5.0–12.5 wt.% ammonium hydroxide, two different photocatalysts (TiO₂ and ZnO) in the presence of molecular oxygen in a batch reactor at 60 °C. Various solid-to-liquid ratios (1:20–1:50) were also tested. Ammonia pretreatment assisted by TiO₂-catalyzed photo-degradation removed 70 % of Klason lignin under the optimum condition (12.5 % ammonium hydroxide, 60 °C, 24 h, solid/liquid?=?1:20, photocatalyst/biomass?=?1:10 with oxygen atmosphere). The enzymatic digestibilities of pretreated corn stover were 85 % for glucan and 75 % for xylan with NH₃-TiO₂-treated solid and 82 % for glucan and 77 % for xylan with NH₃-ZnO-treated solid with 15 filter paper units/g-glucan of cellulase and 30 cellobiase units/g-glucan of β-glucosidase, a 2–13 % improvement over ammonia pretreatment alone.     

白刺与枸杞中微量元素含量的对比研究

采用ICP-AES法对生长在同一区域内的白刺与枸杞根茎中的8种微量元素的含量进行了分析测定。结果表明,两种植物根茎中8种元素含量丰富,并且差异明显,为以后的开发利用提供了基础数据。     

N,B, Si-tridoped mesoporous TiO<Subscript>2</Subscript> with high surface area and excellent visible-light photocatalytic activity

N, B, Si-tridoped mesoporous TiO₂, together with N-doped, N, B-codoped and N, Si-codoped TiO₂, was prepared by a modified sol–gel method. The samples were characterized by wide-angle X-ray diffraction (WAXRD), N₂ adsorption–desorption, transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, UV–visible adsorbance spectra (UV–vis) and X-ray photoelectron spectra (XPS). The N, B, Si-tridoped mesoporous TiO₂ showed small crystallite size, large specific surface area (350 m²/g), uniform pore distribution (3.2 nm) and strong absorption in the visible light region. The photocatalytic activities of the samples were evaluated by the photodegradation of 2,4-dichlorophenol (2,4-DCP) aqueous solution. The N, B, Si-tridoping sample exhibited much higher photocatalytic activity compared with other synthesized photocatalysts. The high activity could be attributed to the strong absorption in the visible light region, large specific surface area, small crystallite size, large amount of surface hydroxyl groups, and mesoporosity.     

Application of chromatography technology in the separation of active alkaloids from Hypecoum leptocarpum and their inhibitory effect on fatty acid synthase

A method that involved the combination of pH‐zone‐refining counter‐current chromatography and semipreparative reversed‐phase liquid chromatography has been established for the preparative separation of alkaloids from Hypecoum leptocarpum. From 1.2 g of crude sample, 31 mg N‐feruloyltyramine, 27 mg oxohydrastinine, 47 mg hydroprotopine, 25 mg leptopidine, and 18 mg hypecocarpine have been obtained. The structure of the new compound, hypecocarpine, is confirmed based on the analysis of spectroscopic data, including NMR, UV, and IR spectroscopy and positive electrospray ionization mass spectrometry. The known chemical structures were characterized on the basis of ¹H and ¹³C NMR spectroscopy. The purities of the five alkaloids are all over 92.7% as determined by high‐performance liquid chromatography. The alkaloids’ cytotoxicity in breast cancer cells is assessed by using a Cell Counting Kit assay and their inhibitory effect on fatty acid synthase expression is assessed by a Western blot assay. These results suggest that leptopidine could suppress growth and induce cytotoxicity in breast cancer cells and that the cytotoxicity of leptopidine may be related to its inhibitory effect on fatty acid synthase expression.     

Bandgaps and vibration isolation of local resonance sandwich-like plate with simply supported overhanging beam

Applied Mathematics and Mechanics - The concept of local resonance phononic crystals proposed in recent years provides a new chance for theoretical and technical breakthroughs in the structural...     

Dopant-free NiOx Nanocrystals: A Low-cost and Stable Hole Transport Material for Commercializing Perovskite Optoelectronics

Advancing inverted (p-i-n) perovskite solar cells (PSCs) is critical for commercial applications given their compatibility with different bottom cells for tandem photovoltaics, low-temperature processability (≤100 °C), and promising operational stability. Although inverted PSCs have achieved an efficiency of over 25 % using doped or expensive organic hole transport materials (HTMs), their synthesis cost and stability still cannot meet the requirements for their commercialization. Recently, dopant-free and low-cost non-stoichiometric nickel oxide nanocrystals (NiO_x NCs) have been extensively studied as a low-cost and effective HTM in perovskite optoelectronics. In this minireview, we summarize the synthesis and surface-functionalization methods of NiO_x NCs. Then, the applications of NiO_x NCs in other perovskite optoelectronics beyond photovoltaics are discussed. Finally, we provide a perspective for the future development of NiO_x NCs for the commercialization of perovskite optoelectronics.     

LC-DAD-ESI-MS Characterization of Carbohydrates Using a New Labeling Reagent

A novel labeling reagent 1-(2-naphthyl)-3-methyl-5-pyrazolone (NMP) coupling to liquid chromatography with electrospray ionization mass spectrometry for the detection of carbohydrates from the derivatized rape bee pollen samples is reported. Carbohydrates are derivatized to their bis-NMP-labeled derivatives. Derivatives showed an intense protonated molecular ion at m/z [M+H]⁺ in positive-ion detection mode. The mass-to-charge ratios of characteristic fragment ions at m/z 473.0 could be used for the accurately qualitative analysis of carbohydrates. This characteristic fragment ion is from the cleavage of C2–C3 bond in carbohydrate chain giving the specific fragment ions at m/z [MH-C _m H_2m+1O _m -H₂O]⁺ for pentose, hexose and glyceraldehydes and at m/z [MH-C _m H_2m-1O _m+1-H₂O]⁺ for alduronic acids such as galacturonic acid and glucuronic acid (m = n ? 2, n is carbon number of carbohydrate). No interferences for all aliphatic and aromatic aldehydes presented in natural environmental samples were observed due to the highly specific parent mass-to-charge ratio and the characteristic fragment ions. The method, in conjunction with a gradient elution, offered a baseline resolution of carbohydrate derivatives on a reversed-phase Hypersil ODS-2 column. The carbohydrates such as mannose, galacturonic acid, glucuronic acid, rhamnose, glucose, galactose, xylose, arabinose and fucose can successfully be detected.     

Surface modification of cetyltrimethylammonium bromide-capped gold nanorods to make molecular probes

A chemical procedure to replace the cetyltrimethylammonium bromide (CTAB) cap on gold nanorods (GNRs) fabricated through seed-mediated growth with organothiol compounds [3-animo-5-mercapto-1,2,4-triazole (AMTAZ) and 11-mercaptoundecaonic acid (MUDA)] was developed to reduce the cytotoxity of GNRs and facilitate further biofunctionalization. Compared to phosphatidylcholine (PC) modification, our procedure yields stable GNRs that are biocompatible and suitable for whole-cell studies. The PC-, AMTAZ-, and MUDA-activated GNRs all showed low cytotoxicity. By choosing different organothiols, net positive or negative charges could be created on the nanorod surface, for different applications. Gold nanorod molecular probes (GNrMPs) were fabricated by subsequent attachment of antibodies to the activated GNRs and were used to visualize and detect cell surface biomarkers in normal and transformed human breast epithelial cells, demonstrating the potential of developing novel biosensors using gold nanorods. The sensitivity of GNrMPs made from organothiol-activated GNRs is considerably higher than that of CTAB/PC-activated GNRs, demonstrating that the protocol reported here is favored in developing molecular probes using GNRs.     

Insights into the β-phase of polyfluorene: characterization,regulation, and mechanism

Due to the unique blue-light properties, wide excited emission interval and so on, polyfluorenes (PFs) are among the most promising blue-light polymers that are widely used in organic lasers and organic light-emitting diodes. Usually, PFs exhibit two different phases: α-phase and β-phase, and the β-phase has higher photoluminescence efficiency and carrier mobility than the one of α-phase. Hence, improving the content of β-phase is very important to enhance the device performance. In this paper, we introduce the methods for characterizing the β-phase in PFs and summarize the recent research progress in regulating the β-phase content. Firstly, the differences between the α-phase and the β-phase of PFs in terms of structure, aggregation behavior, and optoelectronic properties are summarized. Then, the characterization for the β-phase, including ultraviolet–visible absorption spectrum (UV–vis), photoluminescence spectrum (PL), and Raman spectrum, transmission electron microscope (TEM), and X-ray diffraction (XRD) are introduced, and the calculating rules for the content of β-phase is also introduced. Furthermore, the methods to increase the content of β-phase are reviewed. Finally, a brief outlook on the challenges and future development prospects of β-phase in PFs are discussed.