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  • Author or Editor: Jiang Li x
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Abstract

The phenomenon of all-elements-sleeping-beauties in science is revealed by four special cases. The ‘sleeping beauties’ prick their fingers on the ‘spindles’ so that they fall into sleep then are awakened by their ‘princes’. The authors speculate that the phenomenon could happen in scientific literatures with high quality.

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The purpose of the study was to investigate the effects of three kinds of flame retardant (FR), boric acid, zinc borate, and borax on the thermal curing behavior of urea–formaldehyde (UF) resin. Both pH value and gel time were measured to study the curing characters of the UF resin with different loading levels of FR. In addition, differential thermal analysis was also used to obtain kinetic analyses parameter. The results showed that boric acid decreased pH value of UF resin, and reduced gel time of the UF resin. There are no significant changes of the UF resin curing characters with different loading levels of FR. The activation energies for curing reaction of UF resins in the presence of boric acid, zinc borate, and borax, were 84.37, 84.41, and 118.4 kJ/mol, respectively, higher than that of the control one (75.38 kJ/mol). All FRs showed adverse effect on the curing behavior of the UF resin.

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Since the term “co-link” was put forward, many scholars have done exploratory investigations to prove the applicability and validity of co-link analysis used in mapping internet structure and mining relationships among internet colonies. All of these studies are based on the whole links in the web called “total co-link analysis”. However, there are both substantive and non-substantive links in the web, and the number of the latter outweights that of the former, which makes the preconditions of total co-link analysis untenable. In this paper, we present “substantive co-link analysis”, and believe it is more sound and valid than “total co-link analysis”. Then exploratory investigations on both total and substantive co-link analysis are carried out with the sample of 20 academic blogs on Library and Information Science, the results of which testify our assumption that “substantive co-link analysis” is more efficient and reasonable than “total co-link analysis”.

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A simple, rapid, and effective high-performance thin-layer chromatographic (HPTLC) method has been established for differentiating among the polysaccharides present in six traditional Chinese medicines (TCM), Cordyceps sinensis, Ganoderma lucidum, Astragalus memberanaceus, Panax ginseng, Panax quinquefolii , and Panax notogiseng . Acid hydrolyzates of the polysaccharides were analyzed by HPTLC with two detection reagents, aniline-diphenylamine-phosphoric acid and ninhydrin, and scanning densitometry. The compounds were separated on silica gel plates with chloroform- n -butanol-methanol-acetic acid-water 4.5:12.5:5:1.5:1.5 ( v/v ) as mobile phase. Seven monosaccharides and two glucuronic acids were used as reference compounds. The results showed that hydrolysis of polysaccharides can release specific molecules present in the herbal species in addition to the monosaccharides present. This is useful for distinguishing the origins of the polysaccharides in Chinese medicines.

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Abstract Passive air samplers (polyurethane foam disks) were deployed at 25 urban sites and 66 rural sites over the period of July to October 2005, partly between October 2005 and January 2006 for about 120 days across China, and analyzed for extractable organo-chlorine /-bromine /-iodine (EOCl/EOBr/EOI) and polychlorinated biphenyls (PCBs) using hybrid neutron activation analysis (NAA) combined with gas chromatographymass spectrometry (GC-MS). The average concentration of EOCl, EOBr, EOI and ΣPCBs among all the sites were 173.7, 3.5, 1.0 and 0.74 ng/d, respectively. Higher values of EOCl/Br/I and PCBs were detected in the areas of high usage and high emission, which were linked to relatively high-income areas in China, while lower in the west ill-developed region of China, which indicated that these pollutants mainly came from industrial pollution. Higher EOCl contents in traffic areas stated that the exhaust emission from vehicle was another main source of organochlorines in the air. The relative proportions of the known organochlorines (84 PCB congeners) to total EOCl were 0.02–3.0%, which implied that most of EOCl measured in air were unknown.

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Abstract

ZnO nanosheets were prepared by a facile microemulsion-mediated hydrothermal route, and were characterized by X-ray powder diffraction, field-emission scanning electron microscopy, and transmission electron microscopy. As nano ZnO and bulk ZnO possess the same reaction essence, the relationship between standard molar enthalpies of formation of nano ZnO and bulk ZnO was built by designing a novel thermochemical cycle. Combined with microcalorimetry, standard molar enthalpy of formation of the as-prepared ZnO nanosheets at 298.15 K was successfully acquired as (−333.50 ± 0.29) kJ mol−1. It is an effective strategy for standard molar enthalpies of formation of nano materials through building the relationship with its corresponding bulk material.

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Abstract  

Cross-sections for (n,2n), (n,p), (n,α), and (n,d*) (The expression (n,d*) cross section used in this work includes a sum of (n, d), (n, np) and (n, pn) cross sections) reactions have been measured on erbium isotopes at the neutron energies from 13.5 to 14.8 MeV using the activation technique in combination with high-resolution gamma-ray spectroscopy. Data are reported for the following reactions: 162Er(n,2n)161Er, 164Er(n,2n)163Er, 168Er(n,α)165mDy, 166Er(n,p)166gHo, 170Er(n,α)167Dy, 168Er(n,p)168m+gHo, 170Er(n,p)170gHo, and 170Er(n,d*)169Ho. The cross sections were discussed and compared with experimental data found in the literature, and with the comprehensive evaluation data in ENDF/B-VII.0 and l JEFF-3.1/A libraries.

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Activation cross-sections were measured for the 141Pr(n,γ)142Pr reaction at three different neutron energies from 13.5 to 14.8 MeV. The fast neutrons were produced via the 3H(d,n)4He reaction on Pd-300 neutron generator. The natural high-purity Pr2O3 powder was used as target material. Induced gamma activities were measured by a high-resolution gamma-ray spectrometer with high-purity germanium detector. Measurements were corrected for gamma-ray attenuations, random coincidence (pile-up), dead time and fluctuation of neutron flux. The neutron fluences were determined by the cross section of 27Al(n,α)24Na reaction. The neutron energy in the measurement were by the cross section ratios of 90Zr(n,2n)89m+gZr and 93Nb(n,2n)92mNb reactions. The data for 141Pr(n,γ)142Pr reaction cross sections are reported to be 3.3 ± 0.2, 2.7 ± 0.2 and 2.2 ± 0.2 mb at 13.5 ± 0.2, 14.1 ± 0.2, and 14.8 ± 0.2 MeV incident neutron energies, respectively. Results were discussed and compared with some corresponding values found in the literature.

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