Synthesis of new α-glucosidase inhibitors based on oleanolic acid incorporating cinnamic amides

A series of α-glucosidase inhibitors with the oleanolic acid core and different cinnamic amide ligands were designed and synthesized. Their preliminary structure-activity relationships were analyzed. In general, the compounds with 3,28-disubstituted oleanolic acid exhibited stronger activity than those 28-monosubstituted analogues, and variation of cinnamic amide substitution significantly affected α-glucosidase inhibition activities. Most of the compounds showed potent inhibitory activity against α-glucosidase with much greater efficacy than a typical α-glucosidase inhibitor, acarbose.     

Study of a hydrogen-bombardment process for molecular cross-linking within thin films

A low-energy hydrogen bombardment method, without using any chemical additives, has been designed for fine tuning both physical and chemical properties of molecular thin films through selectively cleaving C-H bonds and keeping other bonds intact. In the hydrogen bombardment process, carbon radicals are generated during collisions between C-H bonds and hydrogen molecules carrying ～10 eV kinetic energy. These carbon radicals induce cross-linking of neighboring molecular chains. In this work, we focus on the effect of hydrogen bombardment on dotriacontane (C(32)H(66)) thin films as growing on native SiO(2) surfaces. After the hydrogen bombardment, XPS results indirectly explain that cross-linking has occurred among C(32)H(66) molecules, where the major chemical elements have been preserved even though the bombarded thin film is washed by organic solution such as hexane. AFM results show the height of the perpendicular phase in the thin film decreases due to the bombardment. Intriguingly, Young's modulus of the bombarded thin films can be increased up to ～6.5 GPa, about five times of elasticity of the virgin films. The surface roughness of the thin films can be kept as smooth as the virgin film surface after thorough bombardment. Therefore, the hydrogen bombardment method shows a great potential in the modification of morphological, mechanical, and tribological properties of organic thin films for a broad range of applications, especially in an aggressive environment.     

Detection of uranium with a wireless sensing method by using salophen as receptor and magnetic nanoparticles as signal-amplifying tags

A new wireless sensing method for the detection of uranium in water samples has been reported in this paper. The method is based on a sandwich-type detection strategy. Salophen, a tetradentate ligand of uranyl ion, was immobilized on the surface of the polyurethane-protected magnetoelastic sensor as receptor for the capture of uranyl ion. The phosphorylated polyvinyl alcohol coated magnetic Fe₃O₄ nanoparticles were used as signal-amplifying tags of uranyl ion. In a procedure of determining uranium, firstly uranyl ion in sample solution was captured on the sensor surface. Then the captured uranyl bound the nanoparticle through its coordination with the phosphate group. The amount of uranium was detected through the measure of the resonance frequency shift caused by the enhanced mass loading on the sensor surface. A linear range was found to be 0.2–20.0 μg/L under optimal conditions with a detection limit of 0.11 μg/L. The method has been applied to determine uranium in environmental water samples with the relative standard deviations of 2.1–3.6 % and the recoveries of 98.0–101.5 %. The present technique is one of the most suitable techniques for assay of uranium at trace level in environmental water samples collected from different sources.     

Fabrication and characterization of composition-gradient CuO/SiO2 composite aerogel

With tetramethoxysilane as the silica precursor, CuCl₂·2H₂O as the copper–oxide precursor, acetonitrile as the solvent and gelled by PO via a sol–gel process, the CuO/SiO₂ composite aerogel was fabricated. By adjusting the amount of CuCl₂·2H₂O, CuO/SiO₂ composite aerogels with different molar ratio of Cu/Si such as 1, 5, 10, 20, 30 and 35 % was prepared. Finally, via a self-built device and sol-co-gelation technic, a continuous formation process was developed to fabricate the composition-gradient CuO/SiO₂ composite aerogel. Density of these aerogels was about 200 mg/cm³, the composition-gradient CuO/SiO₂ composite aerogel was cylindrical and about 2.5 cm in height. Scanning electron microscope was used to characterize its microstructure at different position. X-ray diffraction, energy dispersive spectrometer and Fourier transform infrared spectrometer were used to characterize its composition and composition distribution, the results showed that the cylindrical CuO/SiO₂ composite aerogel’s molar ratio of Cu/Si changed from 31.06 to 4.43 % as the measure point from the bottom up, the whole sample displayed obvious composition-gradient.     

A Combined Experimental and Computational Study of Linear Ruthenium(II) Coordination Oligomers with End‐Capping Organic Redox Sites: Insight into the Light Absorption and Charge Delocalization

Two series of linear ruthenium coordination oligomers, [(Ntpy)Ru_n(tppz)_n?1(tpy)]²ⁿ⁺ (mono‐Ntpy series, n=1–3) and [(Ntpy)₂Ru_n(tppz)_n?1]²ⁿ⁺ (bis‐Ntpy series, n=1–3) have been prepared, where Ntpy is the capping ligand 4′‐di‐p‐anisylamino‐2,2′:6′,2′′‐terpyridine, tppz is tetra‐2‐pyridylpyrazine, and tpy is 2,2′:6′,2′′‐terpyridine. The electrochemical measurements evidence oxidation events from both the amine segments and the metal centers and reduction waves from tppz and the capping ligands. Both series complexes display much enhanced light absorption with respect to model complexes without terminal amine units. Density functional theory (DFT) calculations have been performed on both series and time‐dependent DFT (TD‐DFT) calculations have been performed on the bis‐Ntpy‐series compounds (n=1–4) to characterize their electronic structures and excited states and predict the electronic properties of long‐chain polymers. Upon one‐electron oxidation, the mono‐Ntpy‐series monoruthenium and diruthenium complexes display N⁺‐localized transitions and metal‐to‐nitrogen charge‐transfer (MNCT) transitions in the near‐infrared (NIR) region. DFT and TD‐DFT computations on the one‐electron‐oxidized forms of the mono‐Ntpy‐series compounds (n=1–4) provide insight into the nature of the MNCT transitions and the degree of charge delocalization.     

The important role of quinic acid in the formation of phenolic compounds from pyrolysis of chlorogenic acid

Chlorogenic acid and its two structural components, quinic acid and caffeic acid, were pyrolyzed under reaction conditions simulating the typical pyrolysis conditions inside a burning cigarette. Major phenolic products from pyrolysis of the three acids were quantified and compared to evaluate the respective contribution of the quinic and caffeic acid moieties to the overall phenolic yield in chlorogenic acid pyrolysis. The results show that the most prominent phenolic product of chlorogenic acid is catechol, followed in order by phenol, hydroquinone, and alkylcatechols. Among these phenolics, catechol and alkylcatechols are formed mainly from the caffeic acid moiety of chlorogenic acid, while phenol and hydroquinone are produced predominantly from the quinic acid moiety. The quinic acid moiety can thus contribute more than 40 % of the overall phenolic yields in chlorogenic acid pyrolysis (0.54 mol mol^?1 chlorogenic acid pyrolyzed at 600 °C). Because considerable amounts of free quinic acid and its derivatives exist in tobacco, the results of this study indicate that quinic acid can be an important source of phenolic compounds, especially hydroquinone and phenol, in tobacco smoke.     

Synergistic Effect of Novel Synergists–Transition Metal Ion-incorporated Nickel Phosphates with Intumescent Flame Retardants in Polypropylene

The two kinds of transition metal ion-incorporated nickel phosphates (TMIVSB-1) were synthesized by the hydrothermal method. The flame retardancy and thermal behavior of intumescent flame retardants (IFR), with and without TMIVSB-1 for PP, were investigated by LOI, UL-94 test, thermogravimetric analyses (TGA) and cone calorimetry. TMIVSB-1 can obviously improve the flame retardant behavior of IFR systems according to the results of LOI values and UL-94 test. The results of LOI show that 2 wt% TMIVSB-1 can increase the LOI value by 3–5 unit compared with that of PP/IFR composite. The UL-94 test shows that PP with 20% IFR burns and has no rating, but the addition of a small content 2 wt% of TMIVSB-1 with 18 wt% of IFR can reach a UL-94 V-0 rating. TGA results show that the thermal stability of PP/IFR/TMIVSB-1 increases obviously more than that of PP/IFR when the temperature is above 265°C. From cone calorimetry results, it can be observed that the HRR peaks are not obviously decreased, but the burning time of PP/IFR/FeVSB-1 (351s) and PP/IFR/ZnVSB-1 (380s) is obviously prolonged compared with that of PP/IFR (303s). The real time FTIR spectra (RTFTIR) demonstrates that the addition of TMIVSB-1 further staves the decomposition of the PP composites. The scanning electron microscopy (SEM) indicates the quality of char forming of PP/IFR/ TMIVSB-1 is superior to that of PP/IFR.     

Induced Dual-Nanospray: A Novel Internal Calibration Method for Convenient and Accurate Mass Measurement

Accurate mass information is of great importance in the determination of unknown compounds. An effective and easy-to-control internal mass calibration method will dramatically benefit accurate mass measurement. Here we reported a simple induced dual-nanospray internal calibration device which has the following three advantages: (1) the two sprayers are in the same alternating current field; thus both reference ions and sample ions can be simultaneously generated and recorded. (2) It is very simple and can be easily assembled. Just two metal tubes, two nanosprayers, and an alternating current power supply are included. (3) With the low-flow-rate character and the versatility of nanoESI, this calibration method is capable of calibrating various samples, even untreated complex samples such as urine and other biological samples with small sample volumes. The calibration errors are around 1 ppm in positive ion mode and 3 ppm in negative ion mode with good repeatability. This new internal calibration method opens up new possibilities in the determination of unknown compounds, and it has great potential for the broad applications in biological and chemical analysis.      

Synthesis and antibacterial activity of novel 10, 11-epoxy acylide erythromycin derivatives

A series of novel acylide derivatives have been synthesized from clarithromycin A via a facile procedure. The C-3 modifications involved replacing the natural C-3 cladinosyl group in clarithromycin core with different aryl-piperzine sidechain via chemical synthesis. Meanwhile a distinctive intermediate with 10,11-epoxy moiety was obtained. The structure and stereochemistry of this novel structure were confirmed via NMR and X-ray crystallography. Potential anti-bacterial activities against both Grampositive and Gram-negative bacteria were reported. Because of existence of C10,11-epoxide, these derivatives can be used as intermediates for further structural modification.     

Porous Nitrogen‐Doped Carbon Nanotubes Derived from Tubular Polypyrrole for Energy‐Storage Applications

Porous nitrogen‐doped carbon nanotubes (PNCNTs) with a high specific surface area (1765 m² g^?1) and a large pore volume (1.28 cm³ g^?1) have been synthesized from a tubular polypyrrole (T‐PPY). The inner diameter and wall thickness of the PNCNTs are about 55 nm and 22 nm, respectively. This material shows extremely promising properties for both supercapacitors and for encapsulating sulfur as a superior cathode material for high‐performance lithium–sulfur (Li‐S) batteries. At a current density of 0.5 A g^?1, PNCNT presents a high specific capacitance of 210 F g^?1, as well as excellent cycling stability at a current density of 2 A g^?1. When the S/PNCNT composite was tested as the cathode material for Li‐S batteries, the initial discharge capacity was 1341 mAh g^?1 at a current rate of 1 C and, even after 50 cycles at the same rate, the high reversible capacity was retained at 933 mAh g^?1. The promising electrochemical energy‐storage performance of the PNCNTs can be attributed to their excellent conductivity, large surface area, nitrogen doping, and unique pore‐size distribution.