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Mechanism of selective hydrolysis of alginates under hydrothermal conditions

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Journal of Bioresources and Bioproducts 2022年第3期7卷 173-179页

作者： Taku Michael Aida Yasuaki Kumagai Richard Lee Smith jr Department of Chemical Engineering Faculty of EngineeringFukuoka UniversityNanakuma Jonan-kuFukuoka 814-0180Japan Research Center of Composite Material Fukuoka UniversityNanakuma Jonan-kuFukuoka814-0180Japan Graduate School of Environmental Studies Tohoku UniversityAoba-kuSendai980-8579Japan

Mechanisms of selective hydrolysis of alginates under hydrothermal conditions were investigated by comparing reactivities of sodium alginate(Na-ALG,960 ku)solutions and calcium alginate(Ca-ALG)gels as *** hydrothermal conditions(150°C),hydrolysis of Na-ALG gave product molecular weights of 223,66,26 and 17 ku while those of Ca-ALG gave product molecular weights of 340,102,45 and 31 ku for reaction times of 10,20,30 and 60 min,*** ratios of mannuronic acid(M)to guluronic acid(G)varied only slightly(from 1.3 to 1.2)for Na-ALG over the range of reaction times at 150°C,while ratios(M/G)for Ca-ALG exhibited a remarkable decrease(from 1.1 to 0.8).Diad sequence of alginate products obtained for Na-ALG were 17%,23%,27%and 31%(GG);30%,32%,36%and 38%(MM);and 53%,46%,37%and 32%(GM+MG);while for Ca-ALG they were 18%,22%,24%and 33%(GG);26%,23%,26%and 18%(MM);and 56%,54%,50%and 48%(GM+MG).Reaction mechanisms are proposed for hydrolysis of alginate solutions and alginate gels under hydrothermal conditions;de-polymerization of alginates into monomers and monomeric sequences can be controlled not only by hydrothermal conditions,but also by varying the physical state(solution,gel)of the starting materials.

关键词： Biomaterial Biopolymer De-polymerization High temperature water

Antiviral activities of extracts from Hong Kong seaweeds

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第12期9卷 969-976页

作者： Hui WANG Engchoon Vincent OOI Put O. ANG jr Medical College Jinan University Guangzhou 510632 China Department of Biology the Chinese University of Hong Kong Shatin N. T. Hong Kong China

We extracted six Hong Kong brown seaweed species with hot water for their antiviral properties. The cytotoxicity and antiviral activity of these extracts were tested by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenlytetrezolium bromide] method, cytopathic effect reduction assay, and plaque reduction assay. The antiviral effect was further determined by flow cytometric analysis. The results showed that most of these extracts inhibited the propagation of herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) standard strains with very low cytotoxicity to the host cells. The extracts of Hydroclathrus clathratus and Lobophora variegata showed more potential anti-HSV activities than the extracts of the other four seaweeds. They also had moderate anti- respiratory syncytial virus (RSV) activities but could not inhibit influenza A virus. Hydroclathrus clathratus was further extracted by diluted acid and alkali and the antiviral effects of the extracts were also detected. The result showed that the hot water extract contained the main carbohydrate components that exhibited the antiviral activities against various strains of HSV, including the acyclovir-resistant strain. HI-3, a compound fractionated from this hot water extract, showed a dose-dependent anti-HSV activity in flow cytometric analysis and plaque reduction assay.

关键词： Hong Kong seaweed Hydroclathrus clathratus Antiviral activity Herpes simplex virus (HSV) Flow cytometry

Precipitation Behaviour at the Interface of an Additively Manufactured M789-N709 Hybrid Alloy

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Acta Metallurgica Sinica(English Letters) 2023年第8期36卷 1353-1370页

作者： Kudakwashe Nyamuchiwa Yuan Tian Kanwal Chadha Lu Jiang Thomas Dorin Clodualdo Aranas jr Mechanical Engineering Department University of New BrunswickFrederictonNBE3B 5A3Canada voestalpine Additive Manufacturing Centre Ltd. MississaugaONL5N 7Y3Canada Planetary and Space Science Centre University of New BrunswickFrederictonNBE3B 5A3Canada Institute for Frontier Materials Deakin UniversityGeelongVIC3220Australia

A novel hybrid alloy, designed for plastic injection dies, was fabricated by depositing M789 steel on wrought N709 steel through laser powder bed fusion (LPBF). The M789-N709 interface (with a thickness of about 300 μm) is characterized by the variation of titanium content from 0 wt% in the N709 section to about 1 wt% near the M789 region. A thermodynamic and kinetic simulation after aging treatment was performed to reveal the precipitation behavior in the M789-N709 interface. Different sizes and amounts of ETA-Ni3(Ti,Al) strengthening precipitates exist, with a maximum volume fraction and radius of about 5% and 5 nm, respectively (near the M789 region). Moreover, the volume fraction of precipitates significantly increases with Ti additions of up to 0.6 wt% (i.e., 100 μm from the N709 region);however, beyond this threshold, the increase in the amount of precipitation becomes gradual. The thermodynamic and kinetic simulations performed in the interface are validated by electron diffraction spectroscopy (EDS), electron probe microanalyzer (EPMA) and atomic probe tomography (APT) results;the measured precipitate size from the APT analysis is consistent with the simulation results. Two morphologies of precipitates were detected: elongated and spherical;both contribute to the robustness of the interface. The robust M789-N709 interface formed during the process shows good compatibility between the alloys, which is critical for extended tool life. These new insights about the precipitation at the interface of M789-N709 alloy are crucial in assessing the feasibility of N709 as a cost-effective base material to minimize the use of M789 when printing plastic injection dies.

关键词： Interface Direct aging Laser powder bed fusion Diffusion M789

The effect of total carbon on microscopic soil properties and implications for crop production

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Journal of Arid Land 2012年第3期4卷 251-259页

作者： Inma LEBRON Milton Earl MCGIFFEN jr Donald Louis SUAREZ Centre for Ecology and Hydrology Bangor Gwynedd LL57 2UW UK Department of Botany and Plant Science University of California Riverside CA 92521-0334 USA U.S. Salinity Laboratory Riverside CA 92521-0334 USA

Soil structure is a dynamic property affected by physical, chemical, and microbiological processes. Addition of organic matter to soils and the use of different management practices have been reported to impact soil structure and crop production. Moderation in soil temperature and increases in microbial activity and soil water retention are often suggested as reasons for the rise in crop yield when organic matter is added to the soil. Less is known about the direct effect of changes in soil structure on crop production. A field experiment was conducted to study the effect of summer cover crop and in-season management system on soil structure. The experiment was a nested design with summer cover crop as the main plot and management system as the subplot. Summer cover crop treatments included cowpea （Vigna unguiculata L. Walp.） incorporated into the soil in the fall （CI）, cowpea used as mulch in the fall （CM）, sudangrass （Sorghum vulgare） incorporated into the soil in the fall （S）, and dry fallow or bare ground （B）. Management systems were organic （ORG） and conventional （CNV） systems. Lettuce （Lactuca sativa L.） and cantaloupes （Cucumis melo L.） were cultivated in rotation in the plots for three consecutive years using the same cover crops and management systems for each plot. Disturbed and undisturbed soil cores were collected at the end of the third year and used for laboratory experiments to measure physical, chemical, and hy- draulic properties. Image analysis was used to quantify soil structure properties using a scanning electron micro- scope on thin sections prepared from the undisturbed soil cores. We found that total soil carbon was correlated with porosity, saturation percentage, and pore roughness. Pore roughness was correlated with crop production in gen- eral and with marketable production in particular. We found that the higher the complexity of the pore space, the more water retained in the soil, which may increase soil water residence and reduce plant

关键词： summer cover crop management systems soil structure properties total carbon

Tracking Power System State Evolution with Maximum-correntropy-based Extended Kalman Filter

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Journal of Modern Power Systems and Clean Energy 2020年第4期8卷 616-626页

作者： Julio A.D.Massignan João B.A.London jr. Vladimiro Miranda IEEE Department of Electrical and Computing Engineering School of Engineering of São CarlosUniversity of São PauloSão CarlosBrazil Faculty of Engineering University of Porto and INESC TECPortoPortugal

This paper develops a novel approach to track power system state evolution based on the maximum correntropy criterion,due to its robustness against non-Gaussian *** includes the temporal aspects on the estimation process within a maximum-correntropy-based extended Kalman filter(MCEKF),which is able to deal with both nonlinear supervisory control and data acquisition(SCADA)and phasor measurement unit(PMU)measurement *** representing the behavior of the state variables with a nonparametric model within the kernel density estimation,it is possible to include abrupt state transitions as part of the process noise with non-Gaussian ***,a novel strategy to update the size of Parzen windows in the kernel estimation is proposed to suppress the effects of suspect *** properly adjusting the kernel bandwidth,the proposed MCEKF keeps its accuracy during sudden load changes and contingencies,or in the presence of bad *** with IEEE test systems and the Brazilian interconnected system are carried *** results show that the method deals with non-Gaussian noises in both the process and measurement,and provides accurate estimates of the system state under normal and abnormal conditions.

关键词： Tracking state estimation Kalman filter maximum correntropy power system Parzen window

Intra-Nationalization of Higher Education:The Hong Kong Case

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Frontiers of Education in China 2012年第4期7卷 508-533页

作者： Roger Y.CHAO,jr Department of Asian and International Studies City University of Hong KongHong KongChina

This paper explores the internationalization of higher education initiatives of Hong Kong,being one of the Special Administrative Regions(SAR)of China,within the context of the Chinese Mainland-Hong Kong(CM-HK)***,social,economic,and political ties between Hong Kong and the Mainland of China,their economic and political interdependency,and a time series analysis of Hong Kong’s University Grants Committee(UGC)statistical data(local and non-local participation,geographic composition,and cost analysis of UGC-funded programs)are used to support what the author calls the“intra-nationalization of higher education.”This forms a unique internationalization strategy,whereby a sub-national region such as Hong Kong and possibly Macao,orients its internationalization strategy towards a motherland,in this case China.

关键词： Hong Kong higher education internationalization intra-nationalization regional higher education hub

TopSTO:a 115-line code for topology optimization of structures under stationary stochastic dynamic loading

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Earthquake Engineering and Engineering Vibration 2023年第4期22卷 1081-1100页

作者： Sebastian Pozo Fernando Gomez Thomas Golecki Juan Carrion Billie F.Spencer jr. Civil and Environmental Engineering University of Illinois at Urbana-ChampaignUrbana 61801ILUSA College of Science and Engineering Universidad San Francisco de QuitoDiego de Robles y Vía InteroceanicaQuitoEcuador Skidmore Owings&MerrillLLPChicago 60604ILUSA Department of Civil Engineering University of CuencaCuencaEcuador

The use of topology optimization in structural design under dynamic excitation is becoming more prevalent in the *** many such applications utilize frequency or time domain formulations,relatively few consider stochastic dynamic *** paper presents an efficient and compact code called TopSTO for structural topology optimization considering stationary stochastic dynamic loading using a method derived from random vibration *** theory,described in conjunction with the implementation in the provided code,is illustrated for a seismically excited *** work demonstrates the efficiency of the approach in terms of both the computational resources and minimal amount of code *** code is intended to serve as a baseline for understanding the theory and implementation of this topology optimization approach and as a foundation for additional applications and developments.

关键词： topology optimization stochastic dynamics matlab python

Experimental observation of surface phonon absorption in Zn fine particles coated with ZnO

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Chinese Science Bulletin 1997年第1期42卷 85-86页

作者： Xu, JF Zhang, jr Du, YW Department of Physics and laboratory of Solid State Microstructures Nanjing University Nanjing China

FINE particles have attracted much attention in the past few years due to their unique physical and chemical properties. For gas-evaporated fine metallic particles, a thin oxide layer is usually formed on their surface. According to Ruppin’s prediction, a dielectric coating on metallic particles should have a series of surface modes between ωTO and ωLO, the long-wavelength transverse and longitudinal optical phonon frequencies of the dielectric. The frequency of

关键词： Experimental observation of surface phonon absorption in Zn fine particles coated with ZnO mode

The Strengths and Weaknesses of Conceptual Metaphor Theory： A View from Cognitive Science

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外国语 2008年第2期31卷 2-12页

作者： Raymond W. Gibbs, jr. Department of Psychology University of California Santa Cruz CA 95064 USA

A major revolution in the study of metaphor occurred over 25 year ago with the introduction of "conceptual metaphor theory." Unlike previous theories of metaphor and metaphorical meaning,conceptual metaphor theory,or CMT,proposed that metaphor is not just an aspect of language,but also a fundamental part of human ***,most metaphorical language arises from pre-existing patterns of metaphorical thought or conceptual *** paper provides a brief overview of the linguistic and psychological evidence supporting CMT and describes some of the criticisms of CMT offered by various scholars within cognitive *** of CMT must address these weaknesses in the theory,while critics must acknowledge the strengths of CMT as metaphor scholars from all academic fields work toward a comprehensive theory of metaphoric language and thought.

关键词：隐喻思想认知概念性