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Fraying around the edges:negative effects of the invasive Tradescantia zebrina *** Bosse(Commelinaceae)on tree regeneration in the Atlantic Forest under different competitive and environmental conditions

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Journal of Plant Ecology 2019年第4期12卷 713-721页

作者： Wagner a.chiba de Castro Rafael O.Xavier Federico H.L.Garrido Jair H.C.Romero Cleto K.Peres Ruberval Cda Luz Instituto Latino-Americano de Ciências da Vida e da Natureza Universidade Federal da Integração Latino-Americana(UNILA)Foz do IguaçuPR85867-970Brazil Departmento de Ecologia Universidade de São PauloSão PauloSP05508-090Brazil Departamento de Hidrobiologia Universidade Federal de São CarlosSão CarlosSP13565-905Brazil

Aims Invasive plants modify the structure and functioning of natural en-vironments and threat native plant *** species are often favored by human interference such as the creation of arti-ficial forest *** removal experiments may clarify if invasive plants are detrimental to native plant regeneration and how this is related to other local *** assessed the joint effect of envir-onment and competition with the invasive Tradescantia zebrina on tree species recruitment in an Atlantic Forest *** We carried out the experimental study in the Iguaçu National Park,located in southern Brazil,using 30 plots distributed across five invaded sites during 6 *** counted *** leaves and recorded the abundance and height of tree recruits over time under contrasting environmental(forest edge *** interior)and removal(all aboveground biomass,only *** removal,and control)*** analyzed the effects of environment and re-moval treatment using generalized linear mixed *** Findings The invasive species performed better at the forest edge than in the *** higher competitive pressure of *** led to higher mortality and lower height of tree *** removal favored tree recruitment,especially in the forest *** study shows that *** hampers woody species regeneration in tropical Atlantic Forests,especially at the forest edge.

关键词： plant invasion competition forest edge plant recruitment Tradescantia zebrina inch plant removal treatment

Ductilization of Ni_3Al by Alloying with Substitutional Elements

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Journal of Materials Science & Technology 1993年第6期9卷 391-399页

作者： Department of Metallurgy,Faculty of Engineering,Iwate University,Morioka 020,Japan a.chiba S.Hanada Institute for Materials Research,Tohoku University,Sendai 980,Japan

This paper reviews recent research on ductility improvement of B-undoped Ni_3Al ***_3Al binary alloys with hypostoichiometric compositions show appreciable ductility at room temperature when the samples are prepared by recrystallization annealing after cold pressing,although the alloys with stoichiometric and hyperstoichiometric compositions remain ***-spun ribbons with hypostoichiometric compositions contain fine anti-phase domains (APDs),while no APD can be seen in melt-spun ribbons with a hyperstoichiometric *** ductility in hypostoichiometric Ni_3Al alloys is associated with low ordering energy of the *** addition of ternary elements,which have been classified as γ formers such as Pd,Pt,Cu,Co and *** ductility of Ni_3Al ***,the microstructure of the melt-spun ribbons consists of fine *** addition of γ' formers such as Si,Ti,Zr,V,Nb and Ta leads to brittle intergranular frac- *** APD was observed in the melt-spun ribbons of these ternary alloys.

关键词： ductility Ni_3Al substitutional element

gem-Difluorinative 1,2-azide migration of vinyl azides enables an expedient synthesis of β-difluoroalkyl azides

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Science China Chemistry 2020年第8期63卷 1019-1020页

作者： Jia Hao Pang Shunsuke chiba Division of Chemistry and Biological Chemistry School of Physical and Mathematical SciencesNanyang Technological UniversitySingapore 637371Singapore

Organic azides have shown versatile reactivity to induce various organic transformations for the synthesis of nitrogencontaining organic molecules such as 1,3-dipolar cycloadditions with unsaturated bonds,the Curtius rearrangement,and formation of nitrogen-centered radicals,most of which are driven by the entropic loss of molecular dinitrogen[1].

关键词： azide synthesis enable

Direct measurement of the three-dimensional distribution of leaf area density and light conditions in a mature oak stand by the cube method

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Journal of Forestry Research 2023年第6期34卷 1817-1827页

作者： Chiharu Migita Yukihiro chiba Tanaka Kenzo Forestry and Forest Products Research Institute TsukubaIbaraki 305-8687Japan Japan International Research Centre for Agricultural Sciences TsukubaIbaraki 305-8686Japan

Although the distributions of foliage and light play major roles in various forest functions,accurate,nondestructive measurement of these distributions is difficult due to the complexity of the canopy *** evaluate the foliage and light distributions directly and nondestructively in a mature oak stand,we used the cube method by dividing the forest canopy into small cubes(50 cm per side)and directly measured leaf area density(LAD,the total one-sided leaf area per unit volume,i.e.,cube)and relative irradiance(RI)within each *** distribution of LAD and of RI was highly heterogeneous,even at the same canopy *** heterogeneity reflected the presence of foliage clusters associated with multiple forking *** relationship between cumulative LAD at the canopy surface and average RI followed the Beer-Lambert *** mean light extinction coefficient(K)was ***,K was overestimated by more than double(0.80)when calculated based on the classical method using RI at the forest *** overestimation was caused by the lower RI due to light absorption by nonleaf plant parts below the *** findings on the complex foliage and light distributions in canopy layers should help improve the accuracy of RI and K measurements and thus more accurate predictions of environmental responses and forest functions.

关键词： Beer-Lambert law Canopy structure Foliage cluster Leaf area density Leaf area index Relative light intensity

Visual Person Identification Using a Distance-dependent Appearance Model for a Person Following Robot

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International Journal of Automation and computing 2013年第5期10卷 438-446页

作者： Junji Satake Masaya.chiba Jun Miura Department of Computer Science and Engineering Toyohashi University of Technology

This paper describes a person identifcation method for a mobile robot which performs specifc person following under dynamic complicated environments like a school canteen where many persons *** propose a distance-dependent appearance model which is based on scale-invariant feature transform（SIFT） *** is a powerful image feature that is invariant to scale and rotation in the image plane and also robust to changes of lighting ***,the feature is weak against afne transformations and the identifcation power will thus be degraded when the pose of a person changes *** therefore use a set of images taken from various directions to cope with pose ***,the number of SIFT feature matches between the model and an input image will decrease as the person becomes farther away from the ***,we also use a distance-dependent *** person following experiment was conducted using an actual mobile robot,and the quality assessment of person identifcation was performed.

关键词： Mobile robots image processing intelligent systems identifcation scale-invariant feature transform(SIFT)feature

Isothermal γ →ε phase transformation behavior in a Co-Cr-Mo alloy depending on thermal history during electron beam powder-bed additive manufacturing

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Journal of Materials Science & Technology 2020年第15期47卷 162-170页

作者： Yufan Zhao Yuichiro Koizumi Kenta Aoyagi Kenta Yamanaka Akihiko chiba Department of Materials Processing Graduate School of EngineeringTohoku UniversityAoba-yama 02Aoba-kuSendai980-8579Japan Institute for Materials Research Tohoku University2-1-J KatahiraAoba-kuSendai980-8577Japan

Powder bed fusion with electron beam(PBF-EB),allows Co-Cr-Mo(CCM) implants with patientcustomization to be fabricated with high quality and complex ***,the variability in the properties of PBF-EB-built CCM alloy,mainly due to the lack of understanding of the mechanisms that govern microstructural heterogeneity,brings limitations in extensive *** this study,the microstructural heterogeneity regarding the γ-fcc→ε-hcp phase transformation was *** phase transformation during PBF-EB was analyzed depending on the thermal history that was elucidated by the numerical *** revealed that isothermal γ→ε transformation occurred during the ***,the difference in γ/ε phase distribution was a result of the thermal history determining which method phase transformation was taking place,which can be influenced by the PBF-EB process *** the sample with a low energy input(Earea=2.6 J/mm2),the martensitic transformation was *** the building height increased from the bottom,the e phase fraction *** the other hand,in the sample with a higher energy input(Earea=4.4 J/mm2),the ε phase fo rmed via diffusional-massive transformation and only appea red in a short range of the lower part away from the bottom.

关键词： Powder bed fusion with electron beam Phase transformation Thermal history Numerical simulation

Effects of the aluminum concentration on twin boundary motion in pre-strained magnesium alloys

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Journal of Materials Science & Technology 2021年第14期73卷 116-127页

作者： Yujie Cui Kenta Aoyagi Huakang Bian Yuichiro Hayasaka Akihiko chiba Institute for Materials Research Tohoku UniversitySendai 980-8577Japan The Electron Microscopy Center Tohoku UniversitySendai 980-8577Japan

We investigated the effects of Al concentration on the reciprocated motion of twin boundaries in pre-strained Mg-Al-Zn alloys through a combination of applied compression and tension,in-situ electron-backscattering diffraction observations,and high-angle annular dark-field scanning transmission electron microscopy *** twin growth was restricted by increased Al concentration,which resulted in the occurrence of smaller-sized *** reverse motion of twin boundaries was also restricted,resulting in the formation of higher fractions of secondary twins and 2–5°boundaries during reverse *** secondary twins and 2–5°boundaries mainly contributed to the increased ultimate tensile strength of the pre-strained Mg *** effect is more significant in Mg alloys with larger ***,the increased amount of the Al solute atoms,rather than the precipitates,mainly contributed to the increased strengthening effect on the twin boundary *** research contributes to development of high-strength Mg alloys by stabilizing twin boundaries.

关键词： Hexagonal close packed Magnesium alloy Twinning Dislocations Strength Solute atoms

Effect of mechanical ball milling on the electrical and powder bed properties of gas-atomized Ti-48Al-2Cr-2Nb and elucidation of the smoke mechanism in the powder bed fusion electron b eam melting process

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Journal of Materials Science & Technology 2023年第6期137卷 36-55页

作者： Seungkyun Yim Kenta Aoyagi Keiji Yanagihara Huakang Bian Akihiko chiba Institute for Materials Research Tohoku University2-1-1 KatahiraSendaiMiyagi 980-8577Japan

Smoke is unexpected powder-splashing caused by electrostatic force and is one of the main problems hindering the process stability and applicability of the powder bed fusion electron beam(PBF-EB)*** this study,mechanical stimulation was suggested to suppress smoke of gas-atomized(GA)Ti-48Al-2Cr-2Nb powder using Al_(2)O_(3) and WC ball *** deformation mechanism of the GA powder depending on the ball milling media was discussed based on the developed particle morphology distribu-tion map and contact mechanics *** was revealed that the rapid decrement of flowability and packing density after WC ball milling owing to the formation of angular fragments by the brittle *** variation of surface and electrical properties by mechanical stimulation was investigated via XPS,TEM,and Impedance *** electrical resistivity of the ball-milled powders gradually decreased with increasing milling duration,despite the increased oxide film thickness,and the capacitive response disappeared in Al-60 and WC-30 via metal-insulator *** could be due to the accumulation of strain and defects on the oxide film via mechanical *** smoke mechanism of ball-milled powders was discussed based on the percolation *** the smoke experiment,smoke was more suppressed for WC-10 and WC-20 than that for Al-40 and Al-50,respectively,despite the longer charge dissipation *** could be due to the high probability of contact with conductive *** the Al-60 and WC-30 powders,smoke was further restricted by the formation of a percolation cluster with metal-like electrical *** believe that this study will contribute to a better understanding of the smoke mechanism and process optimization of the PBF-EB.

关键词： Metal-insulator transition Electron beam melting additive manufacturing Packing density Flowability Smoke mechanism Percolation theory

Effect of tumor necrosis factor-α antagonists on oxidative stress in patients with Crohn's disease

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World Journal of Gastroenterology 2015年第35期21卷 10208-10214页

作者： Kazunari Yamamoto Toshimi chiba Takayuki Matsumoto Division of Gastroenterology Department of Internal MedicineSchool of MedicineIwate Medical University

AIM: To investigate changes in oxidative stress in Crohn's disease(CD) before and after anti-tumor necrosis factor(TNF)-α ***: A total of 42 patients with active CD, who were scheduled to be treated by anti-TNF-α antibodies, were enrolled. Serum levels of diacron-reactive oxygen metabolites(d-ROM), biological antioxidant potential(BAP), and modified ratio of oxidative stress and antioxidant capacity(m-OA) were measured using the Free Radical Analytical System before and 8 wk after induction of therapy with infliximab or adalimumab. The values for oxidative stress were correlated with disease activity and clinical response as determined by the CD activity index(CDAI) at 8 and 54 wk after the ***: Prior to treatment, d-ROM showed significant correlations with CDAI(r = 0.42, P < 0.01). There was a significant negative correlation between m-OA and CDAI before and after treatment(r =-0.48 vs r =-0.42, P < 0.01). CDAI and d-ROM had decreased significantly by 8 wk after treatment(CDAI; 223.3 ± 113.2 vs 158.3 ± 73.4, P < 0.01, d-ROM; 373 ± 133 vs 312 ± 101, P < 0.05). However, neither BAP nor m-OA had changed significantly. In patients who had responded to the treatment at 8 wk, d-ROM, BAP, and m-OA levels before treatment did not differ significantly between patients with and without loss of ***: Anti-TNF-α therapy decreases oxi-dative stress in patients with CD, but does not alter the production of antioxidants. Dysregulation of antioxidants may be associated with the disease.

关键词： Crohn’s disease Severity Oxidative stress Anti-tum