Salen–Mg-doped NH2–MIL-101(Cr) for effective CO2 adsorption under ambient conditions

A novel metal-doped metal–organic framework (MOF) was developed by incorporating salen–Mg into NH₂–MIL-101(Cr) structure under ambient conditions. The Schiff base complex was successfully prepared by condensing salicylaldehyde with a free amino group and then coordinating metal ions. Such a structure can endow the sample with higher CO₂ adsorption performance. At 0°C and 1 bar, the salen–Mg-modified sample achieves the maximum adsorption capacity of 2.18 mmol g⁻¹ for CO₂, which was 5.8% higher than the pristine salen–MOF under the same conditions. Notably, the Freundlich model indicates that the CO₂ adsorption process of all samples conforms to reversible adsorption. However, the correlation coefficients (R²) of the Mg-doped sample are lower than that of the pristine sample. Besides, the CO₂/N₂ adsorption selectivity and isosteric heat also show a similar trend. These results indicate that the salen–Mg can enhance the interaction between the material and CO₂ molecules.     

In Vivo Metabolism Study of Timosaponin BIII in Rat Using HPLC-QTOF-MS/MS

Timosaponin BIII, as one of the steroid saponins isolated from Anemarrhena asphodeloides Bge., was proved to have many pharmacological activities in recent years and became a natural active compound with good development prospect. In the present study, a simple and rapid method using high-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry was developed for the determination of the structures of timosaponin BIII and its metabolites in rats after administrating intragastrically at 300 mg kg⁻¹. By comparing their changes in molecular masses (ΔM), retention times and spectral patterns with those of the parent compound, nine metabolites were detected and identified in urine, and eight in plasma as well as four in brain. It is also indicated that the deglycosylation and oxidation reactions were the main metabolic pathways in the biotransformation of timosaponin BIII in vivo and the structures of the nine metabolites were identified and proposed to be timosaponin BII(M1), the hydroxylated metabolite of TBII(M2), the hydroxylated metabolites of TBIII(M3 and M4), deglycosylation and monooxygenation product of TBIII(M5), the deglycosylation product of TBII(M6), timosaponin AIII(M8), the isomers of timosaponin AIII(M7 and M9).

     

Mixed quantization dimensions of self-similar measures

Classical multifractal analysis studies the local scaling behaviors of a single measure. However recently mixed multifractal has generated interest. The purpose of this paper is some results about the mixed quantization dimensions of self-similar measures.     

Synergistic effects between silicon-containing flame retardant and potassium-4-(phenylsulfonyl)benzenesulfonate (KSS) on flame retardancy and thermal degradation of PC

A novel flame retardant (PSiN), containing silicon and nitrogen, was synthesized using N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane (KH-602) and diphenylsilanediol through solution polycondesation and it was used together with potassium-4-(phenylsulfonyl)benzenesulfonate (KSS) to prepare a flame-retardant system for polycarbonate (PC). The structure and thermal property of PSiN were characterized by Fourier transform infrared spectroscopy (FTIR), ¹HNMR and thermogravimetric analysis (TG) tests. Flammability and thermal behaviors of PC/KSS/PSiN systems were estimated by limited oxygen index (LOI), cone calorimeter, vertical burning test (UL-94), and TG tests. The results showed that the flame retardancy and char residues of PC/KSS system were improved with the addition of PSiN. When 1 mass% PSiN and 0.5 mass% KSS were incorporated, the LOI value of PC was found to be 46, and class V-0 of the UL-94 test. Moreover, both the heat release rate and the total heat release of PC/KSS/1 mass% PSiN decreased compared with those of PC and PC/KSS systems. The microstructures observed by scanning electron microscopy and FTIR indicated that the surface of the char for PC/KSS/PSiN system hold a more cohesive and denser char structure when compared with the pure PC and PC/KSS system.     

DNAzyme based electrochemical sensors for trace uranium

We have developed a uranyl-specific DNAzyme that was immobilized on the surface of a gold electrode to give a highly sensitive and selective biosensor for uranyl ion. The typical DNAzyme system consisted of the RNA (rA) as the substrate (ADNA), and the other strand is the enzyme (TDNA) with a ferrocene (Fc). The presence of uranyl ion induces the cleavage of the DNA substrate strand at the rA position to form two fragments. The Fc unit thereby is released from the surface of the electrode, and this results in a decreased peak current. This electrochemical biosensor has a dynamic range from 2 nM to 14 nM of uranyl ion, with a detection limit at 1 nM. It exhibits high sensitivity and excellent selectivity over other metal ions, and thus represents a promising technique for simple, fast, on-site, and real-time electrochemical sensing of UO₂(II) ion. It also serves as a guide in choosing different methods for designing electrochemical sensors for other metal ions.

Solid-phase extraction and preconcentration of trace Pb(II) from water samples with folic acid modified silica gel

A chelating matrix prepared by immobilising folic acid on silica gel-bound amine phase was used as a new solid-phase extractant. This sorbent has been developed only for preconcentration of trace Pb(II) prior to determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions were investigated by batch and column procedures. The optimum pH value for the separation of Pb(II) on the new sorbent was 4.0. The adsorbed Pb(II) was quantitatively eluted by 2.0?cm³ of 0.5?mol?dm^?3 of HCl. Common coexisting ions did not interfere with the separation and determination of Pb(II). The maximum static adsorption capacity of the sorbent under optimum conditions was found to be 69.23?mg?g^?1 for Pb(II). The detection limit of the method defined by International Union of Pure and Applied Chemistry was 0.28?ng?cm^?3. The relative standard deviation (RSD) of the method was lower than 2.0% (n?=?8). The developed method has been validated by analysing certified reference materials and successfully applied to the determination of Pb(II) in water samples with satisfactory results.     

One-pot reaction for the concise synthesis of spiro[benzofuran-2,2′-naphthalen]-1′-one derivatives

A novel one-pot two-step protocol has been developed to synthesize various spiro[benzofuran-2,2′-naphthalen]-1′-one derivatives from the three-component reaction of tetralones, 2-hydroxyphenyl functionalized α,β-unsaturated ketones, and iodine. One C–C bond and one C–O bond have formed during this process. The notable features of this protocol are simple and mild reaction conditions, applicable to a wide range of readily available starting materials, good yields (up to 91%), and excellent stereoselectivities (up to 97:3).     

Design,synthesis and anti-influenza virus activities of terminal modified antisense oligonucleotides

Four novel terminal modified antisense oligonucleotides (ODNs) were designed, synthesized and tested for their anti-influenza virus activity. Initial biological studies indicated that lipophilic and rimantadin emodificated Flutide exhibited more potent anti-H1N1 activity than Flutide. Among them, lipophilic modificated ODN (Flutide-I) showed the most antiviral activity. The EC₅₀ value of Flutide-I for inhibiting H1N1 induced cytopathic effect (CPE) and H1N1 RNA were respectively (0.26 ± 0.16) μM and (0.11 ± 0.03) μM. The cytotoxicity of these compounds has also been assessed. No significant cytotoxicities were found for any of these compounds with the concentrations up to 20 μM.     

基于多孔金结构的三相界面酶电极的制备及高效电化学酶传感性能

界面微环境是影响酶催化反应及酶传感性能的关键因素. 本研究基于三维微纳米结构多孔金基底, 通过调控电极表面的亲水和疏水浸润性, 制备了具有固-液-气三相界面微环境的氧化酶电极, 并研究了界面微环境对酶催化反应动力学的影响规律. 基于所制备的三相界面多孔金结构酶电极, 反应物氧气能够从气相直接快速地传输到酶催化反应界面, 极大地提升了界面氧气浓度及其稳定性, 从而大幅度提高了氧化酶活性及酶电极响应的稳定性. 以葡萄糖为模型待测物, 基于该三相界面酶电极的电化学酶生物传感器拥有宽的线性范围、 高的灵敏度、 低的检出限以及良好的稳定性. 这类独特的三相反应界面设计为高效酶生物传感器的建构以及生物分子的精准检测提供了新思路.