With the development of low dielectric permittivity materials having an ultra-low sintering temperature,testing their dielectric properties at terahertz frequencies suitable for 6G communication systems and implementa...With the development of low dielectric permittivity materials having an ultra-low sintering temperature,testing their dielectric properties at terahertz frequencies suitable for 6G communication systems and implementation of the fabricated materials in ultra-low temperature cofired ceramics(ULTCC)were the main goals of the research.Lithium tungstate Li_(2)WO_(4)was synthesized by a solid-state reaction and used for the preparation of green tapes and test structures with cofired internal conductive layers,which are destined for substrates of microwave and submillimeter wave circuits.Sintering behavior,thermal effects,and mass changes of the green tapes during heating were studied using a hot-stage microscope,differential thermal analysis,and thermogravimetry.A single-phase composition was revealed for being undoped and doped with AlF3–CaB_(4)O_(7)ceramics.The impact of frequency,temperature,the addition of AlF3–CaB_(4)O_(7)and CuBi_(2)O_(4)dopants,and sintering temperature was the subject of in-depth characterization of dielectric properties in a terahertz region.A glass-free composition,ultra-low sintering temperature of 590–630℃,low roughness of the green tapes,dense microstructure,compatibility with Ag conductors,low and stable dielectric permittivity of 5.0–5.8 in a broad range of 0.2–2 THz,and low dielectric loss of 0.008–0.01 at 1 THz are the main advantages of the developed ULTCC substrates.展开更多
This article is the 15th contribution in the Fungal Diversity Notes series,wherein 115 taxa from three phyla,nine classes,28 orders,48 families,and 64 genera are treated.Fungal taxa described and illustrated in the pr...This article is the 15th contribution in the Fungal Diversity Notes series,wherein 115 taxa from three phyla,nine classes,28 orders,48 families,and 64 genera are treated.Fungal taxa described and illustrated in the present study include a new family,five new genera,61 new species,five new combinations,one synonym,one new variety and 31 records on new hosts or new geographical distributions.Ageratinicolaceae fam.nov.is introduced and accommodated in Pleosporales.The new genera introduced in this study are Ageratinicola,Kevinia,Pseudomultiseptospora(Parabambusicolaceae),Marasmiellomycena,and Vizzinia(Porotheleaceae).Newly described species are Abrothallus altoandinus,Ageratinicola kunmingensis,Allocryptovalsa aceris,Allophoma yuccae,Apiospora cannae,A.elliptica,A.pallidesporae,Boeremia wisteriae,Calycina papaeana,Clypeo-coccum lichenostigmoides,Coniochaeta riskali-shoyakubovii,Cryphonectria kunmingensis,Diaporthe angustiapiculata,D.campylandrae,D.longipapillata,Diatrypella guangdongense,Dothiorella franceschinii,Endocalyx phoenicis,Epicoc-cum terminosporum,Fulvifomes karaiensis,F.pannaensis,Ganoderma ghatensis,Hysterobrevium baoshanense,Inocybe avellaneorosea,I.lucida,Jahnula oblonga,Kevinia lignicola,Kirschsteiniothelia guangdongensis,Laboulbenia caprina,L.clavulata,L.cobiae,L.cosmodisci,L.nilotica,L.omalii,L.robusta,L.similis,L.stigmatophora,Laccaria rubriporus,Lasiodiplodia morindae,Lyophyllum agnijum,Marasmiellomycena pseudoomphaliiformis,Melomastia beihaiensis,Nemania guangdongensis,Nigrograna thailandica,Nigrospora ficuum,Oxydothis chinensis,O.yunnanensis,Petriella thailandica,Phaeoacremonium chinensis,Phialocephala chinensis,Phytophthora debattistii,Polyplosphaeria nigrospora,Pronectria loweniae,Seriascoma acutispora,Setoseptoria bambusae,Stictis anomianthi,Tarzetta tibetensis,Tarzetta urceolata,Tetraploa obpyriformis,Trichoglossum beninense,and Tricoderma pyrrosiae.We provide an emendation for Urnula ailaoshanensis Agaricus duplocingulatoides var.brevisporus introduced as a new variety based on morphology a展开更多
The paper reports on the influence of processing on microstructure and electrical properties of multilayer varistors based on zinc oxide doped with Bi2O3,Sb2O3,Co2O3,MnO,Cr2O3,B2O3,and SiO2.0.5–1 wt%of AlF3–CaB4O7 w...The paper reports on the influence of processing on microstructure and electrical properties of multilayer varistors based on zinc oxide doped with Bi2O3,Sb2O3,Co2O3,MnO,Cr2O3,B2O3,and SiO2.0.5–1 wt%of AlF3–CaB4O7 was used as a new effective sintering aid.The behavior of green laminates during heating was characterized using differential thermal analysis and a heating microscope.As revealed by XRD,SEM,and EDS methods,the varistor layers are composed of ZnO grains of 1–5μm size,submicrometer spinel and pyrochlore grains situated at the ZnO grain boundaries,and nanometric Bi2O3-rich films surrounding ZnO grains.Complex impedance studies carried out in the frequency range of 0.01 Hz–2 MHz at temperatures changing from –30 to 150℃ imply the formation of semiconducting grains and insulating grain boundaries.Frequency dependence of dielectric permittivity shows a high plateau at lower frequencies,typical for barrier layer capacitance effect.The fabricated multilayer varistors show nonlinear current–voltage characteristics with a high nonlinear coefficient of 26–38.The breakdown voltage was found to decrease within the range of 66–130 V with sintering temperature increasing from 1000 to 1100℃.Good surge current capability of the varistors was confirmed by the tests using 8/20μs pulses.展开更多
We explore recurrence properties arising from dynamical approach to the van der Waerden theorem and similar combinatorial problems. We describe relations between these properties and study their consequences for dynam...We explore recurrence properties arising from dynamical approach to the van der Waerden theorem and similar combinatorial problems. We describe relations between these properties and study their consequences for dynamics. In particular, we present a measure-theoretical analog of a result of Glasner on multi-transitivity of topologically weakly mixing minimal maps. We also obtain a dynamical proof of the existence of a C-set with zero Banach density.展开更多
基金financed by the National Science Centre,Poland(No.2019/35/B/ST5/02674).
文摘With the development of low dielectric permittivity materials having an ultra-low sintering temperature,testing their dielectric properties at terahertz frequencies suitable for 6G communication systems and implementation of the fabricated materials in ultra-low temperature cofired ceramics(ULTCC)were the main goals of the research.Lithium tungstate Li_(2)WO_(4)was synthesized by a solid-state reaction and used for the preparation of green tapes and test structures with cofired internal conductive layers,which are destined for substrates of microwave and submillimeter wave circuits.Sintering behavior,thermal effects,and mass changes of the green tapes during heating were studied using a hot-stage microscope,differential thermal analysis,and thermogravimetry.A single-phase composition was revealed for being undoped and doped with AlF3–CaB_(4)O_(7)ceramics.The impact of frequency,temperature,the addition of AlF3–CaB_(4)O_(7)and CuBi_(2)O_(4)dopants,and sintering temperature was the subject of in-depth characterization of dielectric properties in a terahertz region.A glass-free composition,ultra-low sintering temperature of 590–630℃,low roughness of the green tapes,dense microstructure,compatibility with Ag conductors,low and stable dielectric permittivity of 5.0–5.8 in a broad range of 0.2–2 THz,and low dielectric loss of 0.008–0.01 at 1 THz are the main advantages of the developed ULTCC substrates.
文摘This article is the 15th contribution in the Fungal Diversity Notes series,wherein 115 taxa from three phyla,nine classes,28 orders,48 families,and 64 genera are treated.Fungal taxa described and illustrated in the present study include a new family,five new genera,61 new species,five new combinations,one synonym,one new variety and 31 records on new hosts or new geographical distributions.Ageratinicolaceae fam.nov.is introduced and accommodated in Pleosporales.The new genera introduced in this study are Ageratinicola,Kevinia,Pseudomultiseptospora(Parabambusicolaceae),Marasmiellomycena,and Vizzinia(Porotheleaceae).Newly described species are Abrothallus altoandinus,Ageratinicola kunmingensis,Allocryptovalsa aceris,Allophoma yuccae,Apiospora cannae,A.elliptica,A.pallidesporae,Boeremia wisteriae,Calycina papaeana,Clypeo-coccum lichenostigmoides,Coniochaeta riskali-shoyakubovii,Cryphonectria kunmingensis,Diaporthe angustiapiculata,D.campylandrae,D.longipapillata,Diatrypella guangdongense,Dothiorella franceschinii,Endocalyx phoenicis,Epicoc-cum terminosporum,Fulvifomes karaiensis,F.pannaensis,Ganoderma ghatensis,Hysterobrevium baoshanense,Inocybe avellaneorosea,I.lucida,Jahnula oblonga,Kevinia lignicola,Kirschsteiniothelia guangdongensis,Laboulbenia caprina,L.clavulata,L.cobiae,L.cosmodisci,L.nilotica,L.omalii,L.robusta,L.similis,L.stigmatophora,Laccaria rubriporus,Lasiodiplodia morindae,Lyophyllum agnijum,Marasmiellomycena pseudoomphaliiformis,Melomastia beihaiensis,Nemania guangdongensis,Nigrograna thailandica,Nigrospora ficuum,Oxydothis chinensis,O.yunnanensis,Petriella thailandica,Phaeoacremonium chinensis,Phialocephala chinensis,Phytophthora debattistii,Polyplosphaeria nigrospora,Pronectria loweniae,Seriascoma acutispora,Setoseptoria bambusae,Stictis anomianthi,Tarzetta tibetensis,Tarzetta urceolata,Tetraploa obpyriformis,Trichoglossum beninense,and Tricoderma pyrrosiae.We provide an emendation for Urnula ailaoshanensis Agaricus duplocingulatoides var.brevisporus introduced as a new variety based on morphology a
基金supported by the National Science Centre, Poland, under the Grant No. 2015/17/D/ST7/04141
文摘The paper reports on the influence of processing on microstructure and electrical properties of multilayer varistors based on zinc oxide doped with Bi2O3,Sb2O3,Co2O3,MnO,Cr2O3,B2O3,and SiO2.0.5–1 wt%of AlF3–CaB4O7 was used as a new effective sintering aid.The behavior of green laminates during heating was characterized using differential thermal analysis and a heating microscope.As revealed by XRD,SEM,and EDS methods,the varistor layers are composed of ZnO grains of 1–5μm size,submicrometer spinel and pyrochlore grains situated at the ZnO grain boundaries,and nanometric Bi2O3-rich films surrounding ZnO grains.Complex impedance studies carried out in the frequency range of 0.01 Hz–2 MHz at temperatures changing from –30 to 150℃ imply the formation of semiconducting grains and insulating grain boundaries.Frequency dependence of dielectric permittivity shows a high plateau at lower frequencies,typical for barrier layer capacitance effect.The fabricated multilayer varistors show nonlinear current–voltage characteristics with a high nonlinear coefficient of 26–38.The breakdown voltage was found to decrease within the range of 66–130 V with sintering temperature increasing from 1000 to 1100℃.Good surge current capability of the varistors was confirmed by the tests using 8/20μs pulses.
基金supported by the National Science Centre (Grant No. DEC-2012/07/E/ ST1/00185)National Natural Science Foundation of China (Grant Nos. 11401362, 11471125, 11326135, 11371339 and 11431012)+1 种基金Shantou University Scientific Research Foundation for Talents (Grant No. NTF12021)the Project of LQ1602 IT4Innovations Excellence in Science
文摘We explore recurrence properties arising from dynamical approach to the van der Waerden theorem and similar combinatorial problems. We describe relations between these properties and study their consequences for dynamics. In particular, we present a measure-theoretical analog of a result of Glasner on multi-transitivity of topologically weakly mixing minimal maps. We also obtain a dynamical proof of the existence of a C-set with zero Banach density.
