Criticalp-Laplacian problems in RN

Summary The main theorem establishes the existence of a positive decaying solution u D ₀ ^1,p (Rⁿ) of a quasilinear elliptic problem involving the p-Laplacian operator and the critical Sobolev exponent pN/(N - p), 1相似文献   

Identification and quantification of 13 components in Angelica sinensis (Danggui) by gas chromatography-mass spectrometry coupled with pressurized liquid extraction

Angelica sinensis (Danggui in Chinese), a well-known traditional Chinese medicine, is also used as a health food product for women's care in Europe and America. Therefore, the demand for Danggui is enormous throughout the world. Due to the shortage of Angelica sinensis, Angelica acutiloba and Angelica gigas are commonly used as the substitutes of Danggui in the market of southeast Asia. However, the three common Angelica roots showed variation in their genetic and chemical composition. Up to date, it is thought that ferulic acid, ligustilide and other phthalides such as butylidenephthalide are the biologically active components of Danggui. In this paper, the contents of 13 compounds including ferulic acid, Z-ligustilide, E-ligustilide, Z-butylidenephthalide, E-butylidenephthalide, 3-butylphthalide, 3-butylidene-4-hydroxyphthalide, senkyunolide A, 6,7-epoxyligustilide, senkyunolide F, senkyunolide H, senkyunolide I, and 6,7-dihydroxyligustilide were determined or estimated by using gas chromatography-mass spectrometry (GC-MS) coupled with pressurized liquid extraction (PLE). The results showed that GC-MS coupled with PLE offered a simple, rapid and high sensitive method to analysis of components in Angelica root. And the contents of investigated compounds in Angelica sinensis, Angelica acutiloba and Angelica gigas, which are used as Danggui in China, Japan and Korea, respectively, were highly variant. It is thought that interaction of multiple chemical compounds contributes to the therapeutic effects of Chinese medicines. However, the overall clinical efficacy of these different Danggui has not been determined. Therefore, comparison of chemical components and pharmacological activities of different Angelica root is helpful to elucidate the mechanism of therapeutic effects of Danggui.     

5种贝类脂肪含量及脂肪酸组成研究

 用氯仿 甲醇法测定了广州海鲜市场上棕带仙女蛤、波纹巴非蛤、文蛤、栉孔扇贝和园华扇贝等 5种贝类的脂肪含量 ,并用GC MS法测定了它们的脂肪酸组成。 5种贝类鉴定出的脂肪酸都在 99% (质量分数 )以上。它们的脂肪含量都大于 1% (质量分数 ) ,园华扇贝的脂肪含量最高。它们的ω 3多不饱和脂肪酸与ω 6多不饱和脂肪酸含量的比值基本上都大于 2。两种扇贝的廿碳五烯酸 (EPA)和廿二碳六烯酸 (DHA)含量都比较高。分析结果表明 ,园华扇贝不仅脂肪含量高 ,而且EPA与DHA的含量也比较高 ,是EPA和DHA理想的提取原料     

Interference of Transformer oil Matrices to the Internal Standards on PCB Quantification

Abstract

Polychlorinated biphenyls (PCBs) are toxic, perssstent, global environmental contaminants which were formulated as complex mixtures of congeners. Many methods have been developed in the past to analyze PCB in transformer oil samples for regulatory purposes. The most important consideration in the cleanup procedure is the ability to remove the oil from the sample matrix, since trace amount of oil will interfere with the subsequent GC-MS analysis. Electron capture detection (ECD) has been the most common method for gas chromatographic analysis of PCBs because of its high sensitivity toward halogenated compounds. ECD can also respond to some non-PCB compound resulting in biased concentrations of PCB. In this work, a two-stage cleanup method, using DMSO liquid/liquid extraction and HPLC column chromatography. has been applied to two types of transformer oil. Five internal standards have been selected to show their performance in the presence of different oil matrices. The comparison of the PCB quantification at different conditions for GC-MS and GC-ECD will be demonstrated.     

Electrochemical Determination of Tyrosine Using Graphene and Gold Nanoparticle Composite Modified Glassy Carbon Electrode

Russian Journal of Electrochemistry - A electrochemical sensor based on graphene and gold nanoparticles modified glassy carbon electrode (GCE) was developed for the determination of tyrosine (Tyr)....     

Non-collinear efficient continuous optical frequency doubling in periodically poled lithium niobate

Non-collinear continuous frequency doubling with relatively high conversion efficiency is demonstrated in periodically-poled lithium niobate. It is shown that about 80% of the total second harmonic energy can be collected to one output channel by tuning incident angle. The fractional phase-matching condition is introduced to interpret the phenomenon. These results make it possible for direct power applications of continuous frequency doubling over the broad spectral range from the visible to the infrared without temperature or angle tuning.     

Facile and Rapid Synthesis of 9H-Carbazole-9-Carboxylic Acids Under Microwave Irradiation

The reaction of halogenated 9H-carbazoles or carbazole with bromoesters in DMF under microwave irradiation readily affords a series of 9H-carbazoles-9-hydroxylic acids.     

Determination of six polyynes in Oplopanax horridus and Oplopanax elatus using polyethylene glycol modified reversed migration microemulsion electrokinetic chromatography

A PEG‐modified reversed migration MEEKC method was developed for simultaneous determination of six polyynes, including oplopandiol, falcarindiol, oplopandiol acetate, (11S, 16S, 9Z)‐9,17‐octadecadiene‐12,14‐diyne‐1,11,16‐triol,1‐acetate, oplopantriol B, and oplopantriol A, in Oplopanax horridus and Oplopanax elatus. The running buffer containing 0.8% v/v ethyl acetate, 3.8% w/v SDS, 6.6% v/v n‐butanol in 20 mM phosphate buffer (pH 2.5), followed by mixing with propan‐2‐ol at 30% v/v and PEG‐1000 at 15% w/v, was applied in the analysis. The proposed method was successfully applied to determine the six polyynes in five samples of Oplopanax horridus and one of O. elatus. The result showed that the types and amounts of polyynes present were obviously different when comparing the two herbs. Besides, the developed PEG‐modified reversed MEEKC method might be suitable for the analysis of hydrophobic analytes in herbal medicines.     

Quantification of Intact and Truncated Stromal Cell-Derived Factor-1α in Circulation by Immunoaffinity Enrichment and Tandem Mass Spectrometry

Stromal cell-derived factor 1α (SDF-1α) or CXCL12 is a small pro-inflammatory chemoattractant cytokine and a substrate of dipeptidyl peptidase IV (DPP-IV). Proteolytic cleavage by DPP-IV inactivates SDF-1α and attenuates its interaction with CXCR4, its cell surface receptor. To enable investigation of suppression of such inactivation with pharmacologic inhibition of DPP-IV, we developed quantitative mass spectrometric methods that differentiate intact SDF-1α from its inactive form. Using top-down strategy in quantification, we demonstrated the unique advantage of keeping SDF-1α’s two disulfide bridges intact in the analysis. To achieve the optimal sensitivity required for quantification of intact and truncated SDF-1α at endogenous levels in blood, we coupled nano-flow tandem mass spectrometry with antibody-based affinity enrichment. The assay has a quantitative range of 20 pmol/L to 20 nmol/L in human plasma as well as in rhesus monkey plasma. With only slight modification, the same assay can be used to quantify SDF-1α in mice. Using two in vivo animal studies as examples, we demonstrated that it was critical to differentiate intact SDF-1α from its truncated form in the analysis of biomarkers for pharmacologic inhibition of DPP-IV activity. These novel methods enable translational research on suppression of SDF-1 inactivation with DPP-IV inhibition and can be applied to relevant clinical samples in the future to yield new insights on change of SDF-1α levels in disease settings and in response to therapeutic interventions.