Search Results
You are looking at 1 - 10 of 36 items for
- Author or Editor: Lin Zhang x
- Refine by Access: All Content x
Abstract
In on—line measurement on sheet thickness by 
-ray transmission, for the sheet thickness vibrates in counting time, and attenuation of -ray which penetrates matter follows an exponential law, not a linear one. So the measured value of thickness which is taken from mean counting rate deviates from the true value.The paper analyses the causes of this deviation, describes the expression form of the dynamic error which is induced by these deviatons, gives a method to diminish the dynamic error by correcting the deviation.
Abstract
In an earlier exercise some demographic methods were reformulated for application in a scientometric context. Age-pyramids based on annual publication output and citation impact was supplemented by the change of the mean age of the publications in the h-core at any time. Although the method was introduced to shed some demographic–scientometric light on the career of individual researchers, the second component, i.e., the age dynamics of the h-core can however be applied to higher levels of aggregation as well. However, the found paradigmatic shapes and patterns do not only characterise individual careers and positions, but are also typical of life cycles and subject-specific peculiarities. In the present study, the proposed approach is used to visualise the careers of scientists active in different fields of the sciences and social sciences and notably the second component, the h-core dynamics, is extended to the analysis of scientific journals from the same fields. In addition to the dynamics of productivity and citation impact, the evolution of co-authorship patterns of the same scientists is studied to capture another facet of individual academic careers.
Abstract
Q-measures express the bridging function of nodes in a network subdivided into two groups. An approach to Q-measures in the context of weighted or valued directed networks is proposed. This new approach uses flow centrality as the main concept. Simple examples illustrate the definition.
Abstract
Nanoscience and technology (NST) is a young scientific and technological field that has generated great worldwide interest in the past two decades. Previous bibliometric analyses have unmistakably demonstrated the remarkable growth of the global NST literature. While almost all published research articles in NST are in English, increasingly a larger share of NST publications is published in the Chinese language. Perplexingly, Chinese is the only language — apart from English — that displays an ascendant trend in the NST literature. In this brief note, we explore and evaluate three arguments that could explain this phenomenon: coverage bias, language preference, and community formation.
Abstract
Polymer-modified TiO2 was found to be a new, efficient photocatalyst for the photodegradation of organic pollutants. Another novel sensitizer-poly(fluorene-co-bithiophene) (PFB) was presented in this study. Varying the bithiophene content of PFB from 10, 20, 33, 40 to 50% in molar ratio, a series of copolymers (PFB10, PFB20, PFB33, PFB40 and PFB50) were prepared and used as the sensitizers for TiO2. The photodegradation rates of phenol catalyzed by these polymer-modified titanium dioxide composites under the irradiation of the GaN LED clusters were investigated. It was found that PFB33-modified TiO2 was the most efficient photocatalyst although the absorption spectrum of PFB50 was broader than that of PFB33.
Summary
The elastic scattering cross sections of natural vanadium for protons have been measured for beam energies below 2.64 MeV in steps of 10 keV and in the angular 160° and 170°. The overall standard error (ΔσExp/σExp) in the measured cross sections is estimated to be better than ±3% at all the beam energies and angles. The results are presented in graphical and tabular forms that should be useful for those who wish to use the cross sections for material analysis.
Abstract
Two linear triblock copolymers poly(t-butyl methacrylate-b-2-hydroxyl ethyl methacrylate-b-N,N-dimethylaminoethyl methacrylate) (PtBMA97-b-PHEMA18-b-PDMAEMA98) and poly(t-butyl methacrylate-b-glycidyl methacrylate-b-styrene) (PtBMA137-b-PGMA23-b-PSt156) were controlled synthesized with living RAFT polymerization technique under the chain transfer of cumyl dithiobenzoate. The results of FT-IR spectra illustrate that the characteristic groups of copolymer fit well with the result of 1H-NMR, which successfully determines the corresponding molecular structure of triblock copolymers. The thermal stability of PtBMA-b-PGMA-b-PSt and PtBMA-b-PHEMA-b-PDMAEMA was also complementarily explained by the activation energy of thermal decomposition from Friedman differential method and Ozawa–Flynn–Wall integral method. The results show that the degradation energy of the former copolymer was much higher than that of the latter copolymer, because the aromatic groups were introduced into the polymer segments of the former copolymer during the RAFT polymerization process, and the other reason is the oxirane rings are typically reactive which they occurred intermolecular crosslinking reaction during the thermal decomposition.
Abstract
This study aims at detecting the role of individual journals and uncovering structural patterns of information flow among scientific journals in a cross-citation network, using different bibliometric indicators and statistical methods of data analysis. Beyond measuring the individual journals’ position within the communication network, we shed light on their cognitive background as well. Language barrier and lacking internationality proved one of the main hindrances for integration into the communication network. Moreover, some document types hinder journals from establishing self-links. Against our expectations, we have found a clear divergence between strongly interlinked and high-entropy journals. Furthermore, the analysis of strong links among different fields allows the detection of high-interdisciplinary journals.
Abstract
A new ecomaterial, zirconyl molybdopyrophosphate (ZMPP), was prepared by a coprecipitation method. The removal of Cs+ and Sr2+ ions from simulated strong acid HLLW using the ion exchange process on ZMPP had been investigated. It showed that there are more than 90% Cs+ and Sr2+ removed from the simulated HLLW on ZMPP despite the presence of other metal ions, such as Na+, Al3+, Fe3+, etc. in excess. Then ZMPP may likely be a selective ion exchanger for the removal of 137Cs and 90Sr directly from strong acid HLLW.
Abstract
In order to determine the fission yields of lanthanides precisely, lanthanides with carriers of 1–2 mg per element are separated from each other by means of pressurized cation exchange chromatography-
HIBA concentration gradient elution: The effects of initial loading technique, concentration gradient, flow rate, and temperature on separation were investigated in detail. Under the optimum conditions adopted according to the results given in this work, all the lanthanides can be completely separated within about 90 minutes with a recovery of more than 95% and purity higher than 99%.
