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- Author or Editor: Jing Xu x
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Abstract
This article examines Handel's opera Orlando from the period of the new Royal Academy of Music (1729–1734). Handel's operas contain many compelling musical elements which impart information and contribute to the richness of his dramatic acts. This article illustrates the various components of compositional practices such as harmonic progression, rhythm, key changes, and chromaticism in Orlando. The second part explores the application of his theatrical gesture of opera. His music releases the meaning of the texts and conveys the content of expression to the audience in a unique way. Finally, this article studies and examines the overture and three arias of the character Zoroastro from Handel's Orlando by comparing several adjacent arias as a group. By studying the role of Zoroastro, we will find that Handel's musical language in opera contains a hidden complexity displayed through the following: expression of tonality and key signature; certain qualities or characteristics of a wider range both in the vocal line and orchestra; and application of ostinato and cross-rhythm in order to enhance the textual meaning. The study shall benefit our ongoing comprehension of Handel's power for evoking the audience's interest, attention, and admiration which are identified when listening to, performing, and analyzing his arias.
Abstract
A method for continuous determination of the light rare earth elements (LREEs) and thorium in Baotou Iron Ore was established. The light rare earths and thorium were adsorbed on a micro-column packed with HD-8 cation exchange resins. The light rare earth elements were eluted with 4 mol L−1 HCl–2 mol L−1 NH4Cl solution and determined with tribromo-arsenzao by a 721-E spectrophotometry at 630 nm; thorium was eluted with 5% potassium oxalate solution and determined with Arsenazo III by a 721-E spectrophotometry at 660 nm. The measured values by the proposed method were in close agreement with the certified values (Baotou main ore standard sample, Baotou ore R-715 standard sample and GSD-2 standard sample). The RSD of the light rare earths and thorium in Baotou Iron Ore were of <1.70% and <1.99%, respectively.
Abstract
Non-isothermal crystallization kinetics and subsequent melting behavior for three kinds of ethylene-acrylic acid copolymer (EAA) are investigated via differential scanning calorimetry (DSC). From the Jeziorny method, the crystallization rate of the primary stage is significantly influenced by the competitive mobility of chains. While the crystallization rate in the secondary stage decreases in order of acrylic acid (AA) content in copolymers. Mo’s method can also provide a good fitting. Difference between the Jeziorny method and Mo’s method analysis is because of a higher effect of non-crystallizable chain ends. The effective activation energy is also determined via Kissinger’s method.
Abstract
Non-isothermal crystallization kinetics of the ethylene–acrylic acid copolymer (EAA) in diluents during thermally induced phase separation (TIPS) process was investigated via differential scanning calorimetry (DSC). Dioctyl phthalate (DOP), diphenyl ester (DPE), and peanut oil were used as diluents. Kinetic models, such as Jeziorny theory, Ozawa theory, and Mo’s approach, were utilized for description. The effective activation energy of EAA component in mixture was calculated by Friedman’s method. In the results, the Jeziorny theory and Mo’s approach could obtain good linear fitting relationship with the primary crystallization behavior of EAA, but the Ozawa theory failed to get a suitable result. The homogeneous nucleation of EAA proceeded at the end of liquid–liquid phase separation, while the non-isothermal crystallization developed within a solid–liquid phase separation environment. In the mixtures, the molecular weight, polar groups, and conformation of the diluent molecules would affect the nucleation of EAA, and its growth rate. Comparing with the non-isothermal crystallization of neat EAA, EAA in diluents obtained a higher Avrami index n, and comparatively lower crystallization rate. Peanut oil facilitated the homogeneous nucleation of EAA, leading to a higher melting peak temperature of EAA in the subsequent melting endotherms. The largest EAA’s Avrami index obtained in peanut oil also indicated a higher crystal growth dimensional geometry. The crystallization rate and crystallinity of EAA during the non-isothermal process decreased in the sequence: EAA/DPE > EAA/DOP > EAA/peanut oil.
Abstract
A rapid and simple method for the determination of stearic acid and 12-hydroxystearic acid in PEG-60 hydrogenated castor oil by high performance liquid chromatography with evaporative light scattering detection was established. The oil sample was first pretreated by alkaline hydrolysis. The analysis was performed on a Zhongpu Develop XD-C18 column (250 mm × 4.6 mm, 5 µm) with gradient elution of methanol and 1% acetic acid aqueous solution at a flow rate of 1.2 mL·min−1 and a column temperature of 40 °C. The drift tube temperature of the evaporative light scattering detection system was set at 40 °C, and the pressure of carrier gas (N2) was 337 kPa. The regression equation revealed a good linear relation (r = 0.9993–0.9995) during the test ranges (119.1–1190.7 μg·mL−1 for 12-hydroxystearic acid, 10.7–107.4 μg·mL−1 for stearic acid). The detection limits of 12-hydroxystearic acid and stearic acid were 1.1 and 2.5 μg·mL−1, the limits of quantitation were 3.2 and 7.4 μg·mL−1, respectively. And the mean recoveries were 101.5 and 101.0%, the corresponding relative standard deviations (RSDs) were 2.1 and 2.8%, respectively. The RSDs corresponding to repeatability (n = 6) were both less than 1.7% in terms of precision. As to the stability, the test results remained stable after 8 h at room temperature (RSDs were both less than 2.6%). The developed method showed high sensitivity, recovery, repeatability and stability, which indicated that the method could be applied as a quality evaluation method for the determination of stearic acid and 12-hydroxyoctadecanoic acid in PEG-60 hydrogenated castor oil.
Abstract
A simple, rapid, and environmentally friendly sample preparation method for pyrethroids determination in cereals using cyclodextrin-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplets coupled with high-performance liquid chromatography was established. The cereal samples were extracted with acetonitrile, cleaned up, and concentrated by green extractant menthol via γ-cyclodextrin assisted extraction process. The extractant menthol dispersed as fine droplets in the cyclodextrin solution and then solidified at room temperature for efficient extraction and convenient collection. The optimized method provided good linearity in the range of 0.01–10 mg kg−1 with limits of detection of 3.5–9.5 μg kg−1. The fortified recoveries of three pyrethroids (i.e., lambda-cyhalothrin, deltamethrin, and bifenthrin) in four cereals (i.e., rice, wheat, maize, and millet) at three levels were in the range of 77.6–101.6% with relative standard deviations of 0.6–6.6%. Overall, the proposed method can be successfully applied for the determination of pyrethroids in cereals.
Abstract
Perampanel (PER) is the first clinically available selective antagonist of α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor approved globally for the treatment of epilepsy. Studies have recently underlined the significant association between dose-exposure-effect-adverse events of PER in patients with epilepsy, so the therapeutic drug monitoring (TDM) of PER is critical in clinical practices, especially for pediatric patients with drug-resistant epilepsy. Due to several limits in previous published analytical methods, herein, we describe the development and validation of a novel liquid chromatography tandem mass spectrometry (LC-MS/MS) method for monitoring PER in human plasma samples. Protein precipitation method by acetonitrile containing PER-d5 as internal standard was applied for the sample clean-up. Formic acid (FA, 0.2 mM) in both aqueous water and acetonitrile were used as the mobile phases and the analyte was separated by an isocratic elution. Qualification and quantification were performed under positive electrospray ionization (ESI) mode using the m/z 350.3 → 219.1 and 355.3 → 220.0 ions pairs transitions for PER and PER-d5, respectively. Potential co-medicated anti-seizure medications (ASMs) have no interference to the analysis. Calibration curves were linear in the concentration range of 1.00–2,000 ng mL−1 for PER. The intra- and inter-batch precision, accuracy, recovery, dilution integrity, and stability of the method were all within the acceptable criteria and no matrix effect or carryover was found. This method was then successfully implemented on the TDM of PER in Chinese children with drug-resistant epilepsy. We firstly confirmed the apparent inter- and intra-individual PER concentration variabilities and potential drug-drug interactions between PER and several concomitant ASMs occurred in Chinese pediatric patients, which were also in line with previous studies in patients of other race.
Abstract
As degradation product of Antineoplaston A10 in vivo, phenylacetyl glutamine showed antitumor activities. According to literatures, we designed and radiosynthesized a phenylacetyl glutamine derivative, which was achieved under a mild reaction condition. Evaluations in vitro and in vivo were performed on tumor bearing mice. Excitingly, the radiochemical purity of (S)-2-((S)-2-(4-(3-fluoropropyl)benzamido)-3-phenylpropanamido)pentanedioic acid ([18F]FBPPA) was 98%, and besides the best radiochemical yield was up to 46%. T/Bl (Tumor/Blood) and T/M (Tumor/Muscle) ratios of [18F]FBPPA at 60 min post injection were 2.33 and 3.51. Meanwhile, it showed satisfied stability in vitro and in vivo, compared with 2-[18F]fluorodeoxyglucose ([18F]FDG). Although [18F]FBPPA deserved further studies to make optimizations on its structure, the results revealed it might become a potential PET imaging agent for detecting tumors.
Abstract
d-glucosamine at concentration of certain range could kill tumor cells without influencing normal cells. There are also some reports on the antitumor activity of d-glucosamine and its derivatives in murine models. It was therefore postulated that d-glucosamine might have the potential to invade tumor cells. We designed and radiosynthesized a glucosamine derivative, N-(2-[18F]fluoro-4-nitrobenzoyl)glucosamine ([18F]FNBG([18F]7)). Evaluations in vitro and in vivo were performed on tumor bearing mice. Excitingly, the radiochemical purity of [18F]FNBG([18F]7) was 99%, and besides the best radiochemical yield was up to 35%. The best T/Bl (Tumor/Blood) and T/M (Tumor/Muscle) ratios of [18F]FNBG([18F]7) were 4.40 and 4.84. Although [18F]FNBG([18F]7) deserved further studies, the results revealed it might become a potential PET imaging agent for detecting tumors.
Background and aims
Internet addiction disorder (IAD) is common in university students. A number of studies have examined the prevalence of IAD in Chinese university students, but the results have been inconsistent. This is a meta-analysis of the prevalence of IAD and its associated factors in Chinese university students.
Methods
Both English (PubMed, PsycINFO, and Embase) and Chinese (Wan Fang Database and Chinese National Knowledge Infrastructure) databases were systematically and independently searched from their inception until January 16, 2017.
Results
Altogether 70 studies covering 122,454 university students were included in the meta-analysis. Using the random-effects model, the pooled overall prevalence of IAD was 11.3% (95% CI: 10.1%–12.5%). When using the 8-item Young Diagnostic Questionnaire, the 10-item modified Young Diagnostic Questionnaire, the 20-item Internet Addiction Test, and the 26-item Chen Internet Addiction Scale, the pooled prevalence of IAD was 8.4% (95% CI: 6.7%–10.4%), 9.3% (95% CI: 7.6%–11.4%), 11.2% (95% CI: 8.8%–14.3%), and 14.0% (95% CI: 10.6%–18.4%), respectively. Subgroup analyses revealed that the pooled prevalence of IAD was significantly associated with the measurement instrument (Q = 9.41, p = .024). Male gender, higher grade, and urban abode were also significantly associated with IAD. The prevalence of IAD was also higher in eastern and central of China than in its northern and western regions (10.7% vs. 8.1%, Q = 4.90, p = .027).
Conclusions
IAD is common among Chinese university students. Appropriate strategies for the prevention and treatment of IAD in this population need greater attention.
