Interpolation inequalities for derivatives in variable exponent Lebesgue–Sobolev spaces

We show the interpolation inequalities for derivatives in variable exponent Lebesgue–Sobolev spaces by applying the boundedness of the Hardy–Littlewood maximal operator on L^p(⋅)$L^{p(\cdot )}$.     

Capillary electrophoresis for simultaneous analysis of heparin, chondroitin sulfate and hyaluronic acid and its application in preparations and synovial fluid

A simple and accurate capillary electrophoresis (CE) method was developed to simultaneously separate and quantify heparin, chondroitin sulfate and hyaluronic acid. The relative standard deviations (intra-day) of migration time, peak height and peak area for heparin, chondroitin sulfate and hyaluronic acid were lower than 1.11, 5.45 and 2.82%, respectively. The limits of detection of heparin, chondroitin sulfate and hyaluronic acid were 0.91, 0.12 and 9.04 × 10(-3) mg/mL, respectively. The developed electrophoretic method was successfully applied to the analysis of commercial drug products and biological samples containing chondroitin sulfate and/or hyaluronic acid. The recoveries for chondroitin sulfate and hyaluronic acid were in the range of 95.9 ~107.0%. This was the first time the content of hyaluronic acid in the synovial fluids from osteoarthritic rabbits was investigated by CE. The results suggested that hyaluronic acid in the synovial fluids from osteoarthritic rabbits may be further metabolized and the administration of chondroitin sulfate or hyaluronic acid could affect the content and metabolism of hyaluronic acid in the synovial fluids. The developed CE method was simple to implement without sample pretreatment such as depolymerisation, very repeatable and easily transferred from lab to lab.     

Detection of chlorogenic acid in honeysuckle using infrared-assisted extraction followed by capillary electrophoresis with UV detector

In this study, a novel infrared-assisted extraction method coupled capillary electrophoresis (CE) is employed to determine chlorogenic acid from a traditional Chinese medicine (TCM), honeysuckle. The effects of pH and the concentration of the running buffer, separation voltage, injection time, IR irradiation time, and anhydrous ethanol in the extraction concentration were investigated. The optimal conditions were as follows: extraction time, 30 min; extraction solvent, 80% (v/v) ethanol in water solution; and 50 mmol/L borate buffer (pH 8.7) was used as the running buffer at a separation voltage of 16 kV. The samples were injected electrokinetically at 16 kV for 8 s. Good linearity (r(2) > 0.9996) was observed over the concentration ranges investigated, and the stability of the solutions was high. Recoveries of the chlorogenic acid were from 95.53% to 106.62%, and the relative standard deviation was below 4.1%. By using this novel IR-assisted extraction method, a higher extraction efficiency than those extracted with conventional heat-reflux extraction was found. The developed IR-assisted extraction method is simple, low-cost, and efficient, offering a great promise for the quick determination of active compounds in TCM. The results indicated that IR-assisted extraction followed by CE is a reliable method for quantitative analysis of active ingredient in TCM.     

气相色谱-离子阱质谱联用测定玩具中21种致敏性芳香剂

建立了气相色谱-离子阱质谱联用测定布绒、贴纸和塑料玩具中苯甲醇等21种致敏性芳香剂的方法。对于布绒和贴纸玩具样品,采用丙酮超声振荡提取20 min后过0.45 μm滤膜,经HP-1MS色谱柱(50 m×0.2 mm×0.5 μm)分离,离子阱质谱检测。对于塑料玩具样品,采取溶解-沉淀方式提取,经Envi-carb石墨化碳固相萃取小柱净化,旋蒸、氮吹浓缩,过0.45 μm滤膜后进行测定,外标法定量。方法对不同物质的定量限(LOQ)为0.02～40 mg/kg,线性范围为0.002～50 mg/L,低、中、高3个添加水平的平均回收率为82.2%～110.8%,相对标准偏差(RSD)为0.6%～10.5%。该方法准确、灵敏,可用于玩具中苯甲醇等21种致敏性芳香剂含量的检测。     

Oxidation pattern of small silicon oxide clusters: structures and stability of Si6On (n = 1-12)

We have performed systematic ab initio calculations to study the structures and stability of Si(6)O(n)() clusters (n = 1-12) in order to understand the oxidation process in silicon systems. Our calculation results show that oxidation pattern of the small silicon cluster, with continuous addition of O atoms, extends from one side to the entire Si cluster. Si atoms are found to be separated from the pure Si cluster one-by-one by insertion of oxygen into the Si-O bonds. From fragmentation energy analyses, it is found that the Si-rich clusters usually dissociate into a smaller pure Si clusters (Si(5), Si(4), Si(3), or Si(2)), plus oxide fragments such as SiO, Si(2)O(2), Si(3)O(3), Si(3)O(4), and Si(4)O(5). We have also studied the structures of the ionic Si(6)O(n)(+/-) (n = 1-12) clusters and found that most of ionic clusters have different lowest-energy structures in comparison with the neutral clusters. Our calculation results suggest that transformation Si(6)O(n)+(a) + O --> Si(6)O(n+1)+(a) should be easier.     

Linearly polarized emission of an organic semiconductor nanobelt

Linearly polarized emission has been observed for the nanobelts fabricated from a perylene diimide molecule through both solution-based and surface-supported self-assembling. The measurement of polarized emission was performed over single nanobelts with use of a near-field scanning optical microscope (NSOM) adapted with emission polarization (by putting a planar polarizer before the detector). Rotating the emission polarizer (from 0 degrees to 180 degrees) changed the emission intensity in a way depending on the relative angle between the long axis of the belt and the polarizer with a minimum of intensity detected at ca. 78 degrees, which is indicative of the tilted stacking of molecules along the belt direction.     

Visible photooxidation of dibenzothiophenes sensitized by 2-(4-methoxyphenyl)-4, 6-diphenylpyrylium: an electron transfer mechanism without involvement of superoxide

We report here on a new electron-transfer mechanism for visible-light photooxidation of sulfides in which no superoxide ion is involved. Visible-light irradiation of 2-(4-methoxyphenyl)-4, 6-diphenylpyrylium tetrafluoroborate (MOPDPP(+)BF(4)(-)) in an O(2)-saturated acetonitrile solution containing dibenzothiophene (DBT) results in nearly 100% conversion to oxygenated products, DBT sulfoxide and sulfone. The photooxidation of DBT is initiated by a photoinduced electron-transfer process, where the excited MOPDPP(+) traps an electron from the ground-state DBT to form MOPDPP(*) and DBT radical cation. Such a mechanism is consistent with the studies of laser flash photolysis, electron spin resonance, and fluorescence quenching of the irradiated system. The photogenerated DBT radical cation undergoes a coupling reaction with O(2) to produce the intermediate responsible for the formation of the oxygenated products. The presence of O(2) has no effect on the decay kinetics of the transient absorption of MOPDPP(*), indicating that no redox reaction occurs between MOPDPP(*) and O(2), and thus no superoxide ion (O(2)(*-)) is formed. Moreover, the ESR signal of MOPDPP(*) was significantly enhanced in the presence of O(2), consistent with the assumption that the photogenerated DBT radical cation couples with O(2) to form the oxygen-adduct, which is subject to further reactions (Scheme 3) leading to the final oxygenated products. Similar results have been obtained when using 10-methylacridine hexafluorophosphate (AcrH(+)PF(6)(-), which has similar reduction potential in the ground state as MOPDPP(+)) as the sensitizer. This finding provides a possibility for the photooxidation of sulfides with dioxygen utilizing visible light (solar energy) and is also of significance in clarification of the reaction mechanism.     

One dense and two open chiral metal-organic frameworks: crystal structures and physical properties

Three 3D robust homochiral helical coordination polymers, [Cu(2,2',3,3'-H2odpa)(bpy)] (1), {[Ni4(2,2',3,3'-odpa)2(bpy)4(H2O)4].(H2O)16} (2), and {[Co4(2,2',3,3'-odpa)2(bpy)4(H2O)4].(H2O)14} (3), have been hydrothermally synthesized from a flexible ligand of 2,2',3,3'-odpda (2,2',3,3'-oxydiphthalic dianhydride). Compound 1 crystallized in space group P3(1)21 and has a rare chiral dense qzd 7.(5)9 topology that incorporates single helical substructures with the same accessibility, whereas compounds 2 and 3 crystallized in the space group C2 and possessed isostructural 3D chiral open frameworks based on the homochiral 2D sheets and 4,4'-bpy pillars. TGA and PXRD analyses show that the porous framework of 2 is stable after the removal of solvent water molecules. In contrast, 3 changed its structure to an amorphous one because of the simultaneous loss of solvent and coordination water molecules. 1 is nearly paramagnetic, whereas weak ferromagnetic interactions between M(II) (M = Ni, Co) ions have been found in 2 and 3.     

Attapulgite modified with 2-hydroxy-1-naphthaldehyde as selective solid-phase extractant for determination of copper(II) in environmental samples by ICP-OES

Attapulgite modified with 2-hydroxy-1-naphthaldehyde was prepared and applied to the separation, preconcentration and determination of Cu(II) in aqueous solutions by inductively coupled plasma optical emission spectrometry. Experimental conditions for effective adsorption of trace levels of Cu(II) were optimized using batch and column procedures. The optimum pH value for the separation of Cu(II) on the newly sorbent was 4.0 and complete elution of Cu(II) from the sorbent surface was carried out using 2 mL of 0.01 mol L^?1 HCl. The adsorption capacity for Cu(II) was 25.13 mg g^?1. The detection limits of the method defined by IUPAC were found to be 0.24 μg L^?1 with enrichment factor of 150. The method has been applied to the determination of Cu(II) in certified reference materials and natural water samples with satisfactory results.     

纤维素在离子液体[AMMor]Cl/[AMIm]Cl混合溶剂中的均相乙酰化反应研究

利用混配离子液体N-烯丙基-N-甲基吗啉氯盐(N-allyl-N-methylmorpholinium chloride,[AMMor]Cl)和1-烯丙基-3-甲基咪唑氯盐(1-allyl-3-methylimidazolium chloride,[AMIm]Cl)作为溶剂,乙酰氯为乙酰化试剂,研究了在没有催化剂条件下的纤维素的均相乙酰化反应.生成的醋酸纤维素(CA)的取代度由2.58到3.00.用FT-IR,1HNMR和13CNMR进行表征.结果表明,[AMMor]Cl/[AMIm]Cl混配的离子液体是一种良好的均相乙酰化介质,纤维素C-6,C-3和C-2三个位置上的羟基均发生了乙酰化反应,且得到纯的纤维素醋酸酯.此反应方便可控,简单高效,不仅降低了成本,离子液体比较容易回收,可以再次利用.