The diquark–triquark model is used to explain charmonium-pentaquark states, i.e., Pc(4380) and Pc(4450), which were observed recently by the LHCb Collaboration. For the first time, we investigate the ...properties of the color attractive configuration of a triquark and we define a nonlocal light cone distribution amplitude for pentaquark states, where both diquark and triquark are not pointlike, but they have nonzero size. We establish an effective diquark–triquark Hamiltonian based on spin–orbital interaction. According to the Hamiltonian, we show that the minimum mass splitting between 52+ and 32− is around 100 MeV, which may naturally solve the challenging problem of small mass splitting between Pc(4450) and Pc(4380). This helps to understand the peculiarities of Pc(4380) with a broad decay width whereas Pc(4450) has a narrow decay width. Based on the diquark–triquark model, we predict more pentaquark states, which will hopefully be measured in future experiments.
Recently, a new hadronic structure at around 6.9 GeV was observed in an LHCb experiment. From its limited yet known decay mode, one could still determine that it contains at least four charm quarks ...and hence belongs to the category of exotic state. This finding indicates for the first time the tetracharm exotic states and is therefore quite importance. In this letter, we propose a nature hybrid interpretation for the structure of X(6900), i.e. in 3¯ccc⊗8cG⊗3cc¯c¯ configuration with JPC=0++, and by using the QCD Sum Rule technique we performed mass spectrum calculation. The results showed that the observed X(6900) could be a gluonic tetracharm state, and some other structures may exist, e.g., one around 7.2 GeV in the tetracharm hybrid configuration and with JPC=0−+. We also predict the tetrabottom hybrid states, leaving for future experiment.
Increased anthropogenic nitrogen (N) deposition is driving N-limited ecosystems towards phosphorus (P) limitation. Plants have evolved strategies to respond to P limitation which affect N cycling in ...plant‐soil systems. A comprehensive understanding of how plants with efficient P‐acquisition or ‐use strategies influence carbon (C) and N cycling remains elusive. We highlight how P‐acquisition/-use strategies, particularly the release of carboxylates into the rhizosphere, accelerate soil organic matter (SOM) decomposition and soil N mineralisation by destabilising aggregates and organic‐mineral associations. We advocate studying the effects of P-acquisition/-use strategies on SOM formation, directly or through microbial turnover.
In response to low P availability, plants have evolved a variety of P‐acquisition/‐use strategies. These may affect N cycling by influencing SOM turnover.Two microbial strategies (N-mining and co-metabolism) have been proposed to explain microbially mediated priming effects. We suggest that priming should be explained from the perspective of the capacity of a plant to acquire or utilise P under low-P conditions.Efficient P‐acquisition/-use strategies may change N cycling by affecting SOM decomposition. For example, a highly efficient P-mobilising strategy, carboxylate release, may destabilise aggregates and organic‐mineral associations through chelation of metals (such as Fe, Al) and then accelerate SOM decomposition; flavonoids may work in a similar way.Efficient P‐acquisition/-use strategies may affect SOM formation directly or indirectly through microbial turnover.
About the exotic structure of Zcs Wan, Bing-Dong; Qiao, Cong-Feng
Nuclear physics. B,
July 2021, 2021-07-01, Volume:
968
Journal Article
Peer reviewed
Open access
Very recently a new hadronic structure around 3.98 GeV was observed in BESIII experiment. From its decay modes, it is reasonable for people to assign it to the category of exotic state, say Zcs+, the ...stranged-parter of Zc(3900). This finding indicates for the first time the tetraquark with strange quark in hidden-charm sector, and hence has a peculiar importance. By virtue of the QCD Sum Rule technique, we analyze the Zcs+ about its possible configuration and physical properties, and find it could be configured as a mixture of two types of structures, 1cc¯u⊗1cs¯c and 1cc¯c⊗1cs¯u, or 3cc¯u⊗3¯cs¯c and 3cc¯c⊗3¯cs¯u, with JP=1+. Physically, it then appears to be the emergence of a compound of four possible currents in each configuration, which tells that the single current evaluation of hadron spectroscopy and their decay properties are sometimes not enough. We find that in both cases the energy spectra may fit well with the experimental observation within the uncertainties, i.e. 3.98 GeV, while be noted that the molecular state is not favored by vector-meson-exchange model. Various Zcs+(3980) decay modes are evaluated, which are critical for pinning down its configuration and left for experimental verification. We also predict the mass of Zcs0, the neutral partner of Zcs+(3980), and analyze its dominant decay probabilities.
Motivated by the very recent observations of hidden charm pentaquarks Pc(4312)+, Pc(4440)+ and Pc(4457)+ of the LHCb Collaboration, we systematically study the spectra of the doubly-heavy (with or ...without charm/bottom numbers) pentaquarks and tetraquarks in non-relativistic constituent quark model. The model independent variational method is employed to solve the Schrödinger equation, where the test radial functions adopted are symmetric for the light quarks. In our study, the Pc(4312)+ may be assigned as the ground state with spin-parity 12− or 32−, while the Pc(4440)+ and Pc(4457)+ may be assigned as the excited states with 12−, which might all belong to the sextet with scc¯=1 and sℓ=32. It is notable that our working framework is quite similar to that of Hydrogen molecule, but with different potential structure. We also classify these pentaquarks and tetraquarks in light of the heavy quark symmetry and their decay properties are analyzed. Several promising channels for the observation of doubly-heavy pentaquarks and doubly-heavy tetraquarks in experiment are proposed.
Intercropping is a farming practice involving two or more crop species, or genotypes, growing together and coexisting for a time. On the fringes of modern intensive agriculture, intercropping is ...important in many subsistence or low‐input/resource‐limited agricultural systems. By allowing genuine yield gains without increased inputs, or greater stability of yield with decreased inputs, intercropping could be one route to delivering ‘sustainable intensification’. We discuss how recent knowledge from agronomy, plant physiology and ecology can be combined with the aim of improving intercropping systems. Recent advances in agronomy and plant physiology include better understanding of the mechanisms of interactions between crop genotypes and species – for example, enhanced resource availability through niche complementarity. Ecological advances include better understanding of the context‐dependency of interactions, the mechanisms behind disease and pest avoidance, the links between above‐ and below‐ground systems, and the role of microtopographic variation in coexistence. This improved understanding can guide approaches for improving intercropping systems, including breeding crops for intercropping. Although such advances can help to improve intercropping systems, we suggest that other topics also need addressing. These include better assessment of the wider benefits of intercropping in terms of multiple ecosystem services, collaboration with agricultural engineering, and more effective interdisciplinary research.
Summary
Drought, a primary abiotic stress, seriously affects plant growth and productivity. Stomata play a vital role in regulating gas exchange and drought adaptation. However, limited knowledge ...exists of the molecular mechanisms underlying stomatal movement in trees. Here, PeCHYR1, a ubiquitin E3 ligase, was isolated from Populus euphratica, a model of stress adaptation in forest trees. PeCHYR1 was preferentially expressed in young leaves and was significantly induced by ABA (abscisic acid) and dehydration treatments. To study the potential biological functions of PeCHYR1, transgenic poplar 84K (Populus alba × Populus glandulosa) plants overexpressing PeCHYR1 were generated. PeCHYR1 overexpression significantly enhanced H2O2 production and reduced stomatal aperture. Transgenic lines exhibited increased sensitivity to exogenous ABA and greater drought tolerance than that of WT (wild‐type) controls. Moreover, up‐regulation of PeCHYR1 promoted stomatal closure and decreased transpiration, resulting in strongly elevated WUE (water use efficiency). When exposed to drought stress, transgenic poplar maintained higher photosynthetic activity and biomass accumulation. Taken together, these results suggest that PeCHYR1 plays a crucial role in enhancing drought tolerance via ABA‐induced stomatal closure caused by hydrogen peroxide (H2O2) production in transgenic poplar plants.
In this paper, we investigate the spectra of the prospective hidden-bottom and -charm hexaquark states with quantum numbers
J
PC
=
0
+
+
,
0
-
+
,
1
+
+
and
1
-
-
in the framework of QCD sum rules. ...By constructing appropriate interpreting currents, the QCD sum rules analyses are performed up to dimension 12 of the condensates. Results indicate that there exist two possible baryonium states in
b
-quark sector with masses
11.84
±
0.22
GeV and
11.72
±
0.26
GeV for
0
+
+
and
1
-
-
, respectively. The corresponding hidden-charm partners are found lying respectively at
5.19
±
0.24
GeV and
4.78
±
0.23
GeV. Note that these baryonium states are all above the dibaryon thresholds, which enables their dominant decay modes could be measured at BESIII, BELLEII, and LHCb detectors.
The storage of carbon (C) and nitrogen (N) in soil is important ecosystem functions. Grassland biodiversity experiments have shown a positive effect of plant diversity on soil C and N storage. ...However, these experiments all included legumes, which constitute an important N input through N₂‐fixation. Indeed, the results of these experiments suggest that N₂ fixation by legumes is a major driver of soil C and N storage. We studied whether plant diversity affects soil C and N storage in the absence of legumes. In an 11‐year grassland biodiversity experiment without legumes, we measured soil C and N stocks. We further determined above‐ground biomass productivity, standing root biomass, soil organic matter decomposition and N mineralization rates to understand the mechanisms underlying the change in soil C and N stocks in relation to plant diversity and their feedbacks to plant productivity. We found that soil C and N stocks increased by 18% and 16% in eight‐species mixtures compared to the average of monocultures of the same species, respectively. Increased soil C and N stocks were mainly driven by increased C input and N retention, resulting from enhanced plant productivity, which surpassed enhanced C loss from decomposition. Importantly, higher soil C and N stocks were associated with enhanced soil N mineralization rates, which can explain the strengthening of the positive diversity–productivity relationship observed in the last years of the experiment. Synthesis. We demonstrated that also in the absence of legumes, plant species richness promotes soil carbon (C) and nitrogen (N) stocks via increased plant productivity. In turn, enhanced soil C and N stocks showed a positive feedback to plant productivity via enhanced N mineralization, which could further accelerate soil C and N storage in the long term.
We are facing unprecedented phosphorus (P) challenges, namely P scarcity associated with increasing food demand, and an oversupply of P fertilisers, resulting in eutrophication. Although we need a ...multidisciplinary approach to systematically enhance P-use efficiency, monodisciplinary studies still prevail. Here, we propose to tighten the P cycle by identifying P-efficient crop genotypes, integrating four plant strategies: increasing P-acquisition efficiency, photosynthetic P-use efficiency and P-remobilisation efficiency, and decreasing seed phytate P concentrations. We recommend P-efficient genotypes together with diversified cropping systems involving complementary P-acquisition strategies as well as smart P-fertiliser management to enhance P-use efficiency in agriculture dependent on soil P status. These strategies will reduce P-fertiliser requirements and offsite environmental impacts, while enhancing seed quality for human and livestock nutrition.
Adopting a multidisciplinary approach is crucial to tighten the P cycle; however, current research still focusses on monodisciplinary approaches.Crop genotypes with high efficiency of P acquisition, photosynthetic P use or P remobilisation, or low seed phytate P concentrations are crucial to reduce P-fertiliser input and P-related environmental impact and to enhance micronutrient availability of food and feed.While native plant species differ substantially in their strategies for P acquisition under low P availability, there is also considerable genotypic variation in P-acquisition strategies in crop species and genotypes.At the leaf level, P is preferentially allocated to photosynthetic cells to enhance photosynthetic P-use efficiency, while, at the cellular level, plants maintain a higher ratio of metabolic P to lipid P, and function at very low levels of ribosomal RNA.
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