Characterization of Novel Aminobenzylcantharidinimides and Related Imides by Proton NMR Spectra and Their Effects on NO Induction

Various acidic anhydrides including cantharidin were converted into corresponding aminobenzylcantharidinimide 3a and analogous imides 3b～k (at the ortho, meta, and para positions) with 35%～87% yields by reacting with aminobenzylamines and triethylamine. The two methyl side chains of cantharidinimides 3ao , 3am , and 3ap, and related imides had more than two chiral centers; the lone pair of electrons of nitrogen displayed a different chemical shift and coupling constant in H‐NMR spectra when the amino group of benzylamine was in the ortho position. These cantharidinimides had parent aniline, pyridine, and naphthalene plane structures, and the primary amine nucleophilicity and basicity might reflect the inductive electron’s negative effect on chemical shifts. We prepared cantharidinimides by heating the reactants cantharidin 1a , aliphatic and aromatic acid anhydrides, primary benzylic amines, and aniline derivatives to ca. 200 °C with 3 mL of dry toluene, and 1～2 mL of triethylamine in high‐pressure sealed tubes (Buchi glasuster 0032) to produce cantharidinimides and their analogues in good yields. The para‐aminobenzylic imides showed greater inhibition of nitric oxide (NO) synthesis by NO synthase (NOS) than did ortho‐ and meta‐aminobenzylic imides. Compound 3fp , para‐aminobenzylic norbonane‐imide, had the most potent effect on inducible NOS among the tested compounds and showed 35% inhibition.     

Silicification‐Induced Cell Aggregation for the Sustainable Production of H2 under Aerobic Conditions

Photobiological hydrogen production is of great importance because of its promise for generating clean renewable energy. In nature, green algae cannot produce hydrogen as a result of the extreme sensitivity of hydrogenase to oxygen. However, we find that silicification‐induced green algae aggregates can achieve sustainable photobiological hydrogen production even under natural aerobic conditions. The core–shell structure of the green algae aggregates creates a balance between photosynthetic electron generation and hydrogenase activity, thus allowing the production of hydrogen. This finding provides a viable pathway for the solar‐driven splitting of water into hydrogen and oxygen to develop green energy alternatives by using rationally designed cell–material complexes.     

HPLC柱效对检测水中磺胺二甲基嘧啶色谱条件的影响

研究色谱柱的柱效降低后对高效液相色谱测定水中磺胺二甲基嘧啶色谱条件的影响。比较了新旧色谱柱的分离效果、色谱峰的对称性和峰面积,结果表明,旧色谱柱的柱效降低,对目标物的分离效果变差,目标物的吸收峰面积变小,峰形不对称。对色谱条件进行了优化试验,结果表明,对流动相水相添加0.125%的冰乙酸调节p H值为4.5后色谱峰的峰形对称性和分离效果得到改善。     

Three‐Arm Branched Microporous Organic Nanotube Networks

Here, a novel method is demonstrated for the preparation of three‐arm branched microporous organic nanotube networks (TAB‐MONNs) based on molecular templating of three‐arm branched core–shell bottlebrush copolymers and Friedel–Crafts alkylation reaction. The unique three‐arm branched bottlebrush copolymers are synthesized by a combination of atom transfer radical polymerization, reversible addition‐fragmentation chain transfer polymerization, and ring‐opening polymerization techniques. In this approach, the length and diameter of branched tube units can be well‐controlled by rational molecular design. Moreover, the as‐prepared TAB‐MONNs possess a high surface area and exhibit a superior adsorption capacity for Rhodamine 6G (R6G) and p‐cresol.

     

Biosynthesis of Gold Nanoparticles by Flavonoids from <Emphasis Type="Italic">Lilium casa blanca</Emphasis>

Biosynthesis of gold nanoparticles (GNPs) by flavonoids from Lilium casa blanca has been developed. Several parameters such as pH, reaction temperature, reaction time and concentration of flavonoids were explored to control the formation of the GNPs. The synthesized GNPs were characterized by UV–Vis spectroscopy, transmission electron microscopy and X-ray diffraction. Stability and catalytic activity of the synthesized GNPs were also discussed. The results showed that the synthesized GNPs were in spherical, about 2.6 nm, with a face centered cubic structure. Synthesized GNPs showed good catalytic activity in the reduction of p-nitrophenol (p-NP) to p-aminphenol (p-AP). This method for synthesis of GNPs is simple, economic, nontoxic and efficient.     

Dual-Polarity Ion Trap Mass Spectrometry: Dynamic Monitoring and Controlling Gas-phase Ion–Ion Reactions

A dual-polarity linear ion trap (LIT) mass spectrometer was developed in this study, and the method for simultaneously controlling and detecting cations and anions was proposed and realized in the LIT. With the application of an additional dipolar DC field on the ejection electrodes of an LIT, dual-polarity mass spectra could be obtained, which include both the mass-to-charge (m/z) ratio and charge polarity information of an ion. Compared with conventional method, the ion ejection and detection efficiency could also be improved by about one-fold. Furthermore, ion–ion reactions within the LIT could be dynamically controlled and monitored by manipulating the distributions of ions with opposite charge polarities. This method was then used to control and study the reaction kinetics of ion–ion reactions, including electron transfer dissociation (ETD) and charge inversion reactions. A dual-polarity collision-induced dissociation (CID) experiment was proposed and performed to enhance the sequence coverage of a peptide ion. Ion trajectory simulations were also carried out for concept validation and system optimization.

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Development of nanofibrillated cellulose coated with gold nanoparticles for measurement of melamine by SERS

The objective of this study was to develop nanofibrillated cellulose (NFC)-based substrate for rapid detection of melamine in milk by surface-enhanced Raman spectroscopy (SERS). NFC were served as a highly porous platform to load with gold nanoparticles (AuNPs), which can be used as a flexible SERS substrate with nanoscale roughness to generate strong electromagnetic field in SERS measurement. The NFC/AuNP substrate was characterized by UV–Vis spectroscopy and electron microscopy. Milk samples contaminated by different concentrations of melamine were measured by SERS coupled with NFC/AuNP substrate. The spectral data analysis was conducted by multivariate statistical analysis [i.e. partial least squares (PLS)]. Satisfactory PLS result for quantification of melamine in milk was obtained (R = 0.9464). The detection limit for melamine extracted from liquid milk by SERS is 1 ppm, which meets the World Health Organization’s requirement of melamine in liquid milk. These results demonstrate that NFC/AuNP substrate has improved homogeneity and can be used in SERS analysis for food safety applications.     

Synthesis and properties of novel stilbene-twelve alkyl quaternary ammonium salts as antibacterial optical whitening agents

Four novel stilbene-twelve alkyl quaternary ammonium salts 5a–d were synthesized. All synthesized compounds were characterized by FT-IR, ¹H-NMR and elemental analysis. Compounds 5a–d showed efficient whitening effect on cotton fiber and high fastness. Furthermore, compound 5c showed better stability to light than C186 in aqueous solution. The preliminary biological experiment demonstrated compounds 5a–d possessed significant antibacterial activities. Among them, compound 5d turned out to be the most active compound against Candida albicans with MIC₅₀ 4 μg/mL as well as E. coli with MIC₅₀ 16 μg/mL.     

Hierarchical porous cellulose/activated carbon composite monolith for efficient adsorption of dyes

Cheap and efficient adsorbents to remove contaminants of toxic dye molecules from wastewater are strongly in demand for environmental reasons. This study provides a novel design of a monolithic adsorbent from abundant materials via a facile synthetic procedure, which can greatly reduce the problems of the tedious separation of adsorbents from treated wastes. A hierarchically porous cellulose/activated carbon (cellulose/AC) composite monolith was prepared by thermally-induced phase separation of cellulose acetate in the presence of AC, using a mixture of DMF and 1-hexanol, followed by alkaline hydrolysis. The composite monolith had alarge specific surface area with mesopore distribution. It not only showed high uptake capacity towards methylene blue (MB) or rhodamine B (RhB) but could also simultaneously adsorb MB and RhB from their mixture, in which the adsorption of one dye was not influenced by the other one. Remarkable effects of solution pH, initial concentration of dye (C ₀), contact time, adsorbent dosage and temperature on the adsorption of MB and RhB onto the composite monolith were demonstrated. The binding data for MB and RhB adsorption on the composite monolith fitted the Freundlich model well, suggesting a heterogeneous surface of the composite monolith. The monolith could retain around 90% of its adsorption capacity after 8 times reuse. These data demonstrate that the cellulose/AC composite monolith has a large potential as a promising adsorbent of low cost and convenient separation for dye in wastewater.     

Even factors with a bounded number of components in iterated line graphs

We consider even factors with a bounded number of components in the n-times iterated line graphs L ⁿ (G). We present a characterization of a simple graph G such that L ⁿ (G) has an even factor with at most k components, based on the existence of a certain type of subgraphs in G. Moreover, we use this result to give some upper bounds for the minimum number of components of even factors in L ⁿ (G) and also show that the minimum number of components of even factors in L ⁿ (G) is stable under the closure operation on a claw-free graph G, which extends some known results. Our results show that it seems to be NP-hard to determine the minimum number of components of even factors of iterated line graphs. We also propose some problems for further research.