Exotic invaders may possess novel biochemical weapons that native plants do not have, and these novel biochemical weapons may be more allelopathic than those from native plants to other native competitors. During rang...Exotic invaders may possess novel biochemical weapons that native plants do not have, and these novel biochemical weapons may be more allelopathic than those from native plants to other native competitors. During range expansion, native species also encounter many new plant competitors. Thus, allelochemicals from native expanding species may also be more novel and allelopathic than those from non-expanding species to other plant competitors in the expanded range. We test this hypothesis using the native expanding Merremia boisiana and its non-expanding congener M. vitifolia in year 2012 inthe expanded range inHainan. In petridish bioassays, we found that aqueous extracts of M. boisiana leaves were often less inhibitory or more stimulatory to seed germination and seedling growth of five vegetable species than those of M. vitifolia leaves. In pot culture, we also found that aqueous leaf extracts of the two congeners could both inhibit the growth of a naturally co-occurring plant Paederia scanden, but their effects did not differ from each other. These results indicate that while allelopathy may contribute to the competitive ability of M. boisiana, it may not act as a novel weapon explaining its success in the expanded range in Hainan.展开更多
With rapid development of infrastructures like tunnels and open excavations in Shanghai,investigations on deeper soils have become critically important.Most of the existing laboratory works were focused on the clayey ...With rapid development of infrastructures like tunnels and open excavations in Shanghai,investigations on deeper soils have become critically important.Most of the existing laboratory works were focused on the clayey strata up to Layer 6 in Shanghai,i.e.at depth of up to 40 m.In this paper,Layers 7,9,and 11,which were mostly formed of sandy soils at depth of up to 150 m,were experimentally investigated with respect to physico-mechanical behaviors.The stressestrain behaviors were analyzed by the consolidated drained/undrained(CD/CU)triaxial tests under monotonic loading.One-dimensional(1D)oedometer tests were performed to investigate the consolidation properties of the sandy soils.Specimens were prepared at three different relative densities for each layer.Also,the micro-images and particle size analyzers were used to analyze the shape and size of the sand grains.The influences of grain size,density,and angularity on the stressestrain behaviors and compressibility were also studied.Compared to the other layers,Layer 11 had the smallest mean grain size(D50),highest compressibility,and lowest shear strength.In contrast,Layer 9 had the largest mean grain size,lowest compressibility,and highest shear strength.Layer 7 was of intermediate mean grain size,exhibiting more compressibility and less shear strength than that of Layer 9.Also,the critical state parameters and maximum dilatancy rate of different layers were discussed.展开更多
Merremia boisiana(Gagnep)van Ooststr.is a noxious fast growing woody vine and is able to grow overtop other plants,causing the death of plants underneath and forming monospecies stands.To formulate management response...Merremia boisiana(Gagnep)van Ooststr.is a noxious fast growing woody vine and is able to grow overtop other plants,causing the death of plants underneath and forming monospecies stands.To formulate management responses,we assessed its seed and vegetative reproduction efficacy through indoor and field experiments.The number of flowers counted from bagged infructescences in Guangzhou ranged from 25 to 172,with an average of 80.80.Counting the seeds of bagged infructescences had shown that there were only 1.58 hard testa seeds in each infructescence.Seed vitality tests using red ink indicated that only 68.6%of hard testa and filled seeds were viable.The emergence rate of scarified hard testa seeds in the sand bed was 31.96%.Under imitated natural conditions,8%of hard testa seeds could germinate,and 9%still retained their germination potential in one year.Thus,seedlings should be monitored and removed in a timely fashion after any attempt of clearing.Moving soil or transplanting plant from infested patches should be strictly prohibited at least for several years.All considered,an infructescence contributed 0.3 seedlings.The investigation in the field found no seedlings either inside or at the perimeter of the patch,suggesting scant expansion by means of seed dispersal.Therefore,the elimination effort could be focused on a relatively restricted scale of patches.Of 630 cuttings of young shoots,old shoots and old lying shoots with or without growth regulators,there were only four(or 0.63%)established individuals.Air-layering shoots all died in two months.Poor cuttings and airlayering reproduction indicated that regeneration from fragments of removed stems or accidentally dropped ones was quite unlikely,and thus mechanical removal was safe.展开更多
The exploration of high-performance solution-processible host materials for blue and white electrophosphorescent devices is a key and fundamental challenge in the ongoing development of organic semiconductors.Herein,t...The exploration of high-performance solution-processible host materials for blue and white electrophosphorescent devices is a key and fundamental challenge in the ongoing development of organic semiconductors.Herein,two solution-processible resonance host materials with self-adaptive characteristics are delicately designed and constructed.Because of the dynamic tautomerization upon resonance variation,these smart hosts show self-adaptive and selectively enhanced charge carrier flux at high triplet energy levels.Conferred by the resonance molecules,solution-processed blue and white devices exhibit excellent maximum current efficiencies(CEs)of 29.8 and 57.3 cd A−1,and external quantum efficiencies(EQEs)up to 14.5%and 23.5%,respectively.Our works highlight the significant progress of the solution-processed phosphorescent organic light-emitting diodes(PhOLEDs)using resonance host molecules,potentially furnishing a leap forward in constructing advanced organic semiconductors for next-generation optoelectronic devices.展开更多
文摘Exotic invaders may possess novel biochemical weapons that native plants do not have, and these novel biochemical weapons may be more allelopathic than those from native plants to other native competitors. During range expansion, native species also encounter many new plant competitors. Thus, allelochemicals from native expanding species may also be more novel and allelopathic than those from non-expanding species to other plant competitors in the expanded range. We test this hypothesis using the native expanding Merremia boisiana and its non-expanding congener M. vitifolia in year 2012 inthe expanded range inHainan. In petridish bioassays, we found that aqueous extracts of M. boisiana leaves were often less inhibitory or more stimulatory to seed germination and seedling growth of five vegetable species than those of M. vitifolia leaves. In pot culture, we also found that aqueous leaf extracts of the two congeners could both inhibit the growth of a naturally co-occurring plant Paederia scanden, but their effects did not differ from each other. These results indicate that while allelopathy may contribute to the competitive ability of M. boisiana, it may not act as a novel weapon explaining its success in the expanded range in Hainan.
基金The financial support of the National Natural Science Foundation of China(Grant Nos.42072317 and 41727802)is gratefully acknowledged.
文摘With rapid development of infrastructures like tunnels and open excavations in Shanghai,investigations on deeper soils have become critically important.Most of the existing laboratory works were focused on the clayey strata up to Layer 6 in Shanghai,i.e.at depth of up to 40 m.In this paper,Layers 7,9,and 11,which were mostly formed of sandy soils at depth of up to 150 m,were experimentally investigated with respect to physico-mechanical behaviors.The stressestrain behaviors were analyzed by the consolidated drained/undrained(CD/CU)triaxial tests under monotonic loading.One-dimensional(1D)oedometer tests were performed to investigate the consolidation properties of the sandy soils.Specimens were prepared at three different relative densities for each layer.Also,the micro-images and particle size analyzers were used to analyze the shape and size of the sand grains.The influences of grain size,density,and angularity on the stressestrain behaviors and compressibility were also studied.Compared to the other layers,Layer 11 had the smallest mean grain size(D50),highest compressibility,and lowest shear strength.In contrast,Layer 9 had the largest mean grain size,lowest compressibility,and highest shear strength.Layer 7 was of intermediate mean grain size,exhibiting more compressibility and less shear strength than that of Layer 9.Also,the critical state parameters and maximum dilatancy rate of different layers were discussed.
基金supported by the National Natural Science Foundation of China(Grant No.30370243)The National Nonprofit Institute Research Grant of CATAS-EPPI(No.2007hzs1J005).
文摘Merremia boisiana(Gagnep)van Ooststr.is a noxious fast growing woody vine and is able to grow overtop other plants,causing the death of plants underneath and forming monospecies stands.To formulate management responses,we assessed its seed and vegetative reproduction efficacy through indoor and field experiments.The number of flowers counted from bagged infructescences in Guangzhou ranged from 25 to 172,with an average of 80.80.Counting the seeds of bagged infructescences had shown that there were only 1.58 hard testa seeds in each infructescence.Seed vitality tests using red ink indicated that only 68.6%of hard testa and filled seeds were viable.The emergence rate of scarified hard testa seeds in the sand bed was 31.96%.Under imitated natural conditions,8%of hard testa seeds could germinate,and 9%still retained their germination potential in one year.Thus,seedlings should be monitored and removed in a timely fashion after any attempt of clearing.Moving soil or transplanting plant from infested patches should be strictly prohibited at least for several years.All considered,an infructescence contributed 0.3 seedlings.The investigation in the field found no seedlings either inside or at the perimeter of the patch,suggesting scant expansion by means of seed dispersal.Therefore,the elimination effort could be focused on a relatively restricted scale of patches.Of 630 cuttings of young shoots,old shoots and old lying shoots with or without growth regulators,there were only four(or 0.63%)established individuals.Air-layering shoots all died in two months.Poor cuttings and airlayering reproduction indicated that regeneration from fragments of removed stems or accidentally dropped ones was quite unlikely,and thus mechanical removal was safe.
基金This work was supported by the National Natural Science Foundation of China(21704042,21604039,61875090,51873159,91833306,21674049)the Six Talent Plan of Jiangsu Province(XCL-049)+4 种基金1311 Talents Program of Nanjing University of Posts and Telecommunications(Dingfeng)the Natural Science Fund for Colleges and Universities in Jiangsu Province(17KJB150017)China Postdoctoral Science Foundation Funded Project(2018M642284)the Nanjing University of Posts and Telecommunications Start-up Fund(NUPTSF)(NY219007,NY217140)the Science and Technology Innovation Project for Overseas Students in Nanjing.
文摘The exploration of high-performance solution-processible host materials for blue and white electrophosphorescent devices is a key and fundamental challenge in the ongoing development of organic semiconductors.Herein,two solution-processible resonance host materials with self-adaptive characteristics are delicately designed and constructed.Because of the dynamic tautomerization upon resonance variation,these smart hosts show self-adaptive and selectively enhanced charge carrier flux at high triplet energy levels.Conferred by the resonance molecules,solution-processed blue and white devices exhibit excellent maximum current efficiencies(CEs)of 29.8 and 57.3 cd A−1,and external quantum efficiencies(EQEs)up to 14.5%and 23.5%,respectively.Our works highlight the significant progress of the solution-processed phosphorescent organic light-emitting diodes(PhOLEDs)using resonance host molecules,potentially furnishing a leap forward in constructing advanced organic semiconductors for next-generation optoelectronic devices.
