6 research outputs found
Biochar amendment alters root morphology of maize plant: Its implications in enhancing nutrient uptake and shoot growth under reduced irrigation regimes
IntroductionBiochar amendment provides multiple benefits in enhancing crop productivity and soil nutrient availability. However, whether biochar addition affects root morphology and alters plant nutrient uptake and shoot growth under different irrigation regimes remain largely unknown.MethodsA split-root pot experiment with maize (Zea mays L.) was conducted on clay loam soil mixed with 2% (w/w) of wheat-straw (WSP) and softwood (SWP) biochar. The plants were subjected to full (FI), deficit (DI), and alternate partial root-zone drying (PRD) irrigation from the fourth leaf to the grain-filling stage.Results and discussionThe results showed that, compared to plants grown in unamended soils, plants grown in the biochar-amended soils possessed greater total root length, area, diameter, volume, tips, forks, crossings, and root length density, which were further amplified by PRD. Despite a negative effect on soil available phosphorus (P) pool, WSP addition improved soil available nitrogen (N), potassium (K), and calcium (Ca) pool and cation exchange capacity under reduced irrigation. Even though biochar negatively affected nutrient concentrations in shoots as exemplified by lowered N, P, K (except leaf), and Ca concentration, it dramatically enhanced plant total N, P, K, Ca uptake, and biomass. Principal component analysis (PCA) revealed that the modified root morphology and increased soil available nutrient pools, and consequently, the higher plant total nutrient uptake might have facilitated the enhanced shoot growth and yield of maize plants in biochar-added soils. Biochar amendment further lowered specific leaf area but increased leaf N concentration per area-to-root N concentration per length ratio. All these effects were evident upon WSP amendment. Moreover, PRD outperformed DI in increasing root area-to-leaf area ratio. Overall, these findings suggest that WSP combined with PRD could be a promising strategy to improve the growth and nutrient uptake of maize plants
Non-Fermi liquid behavior in a correlated flatband pyrochlore lattice
Electronic correlation effects are manifested in quantum materials when
either the onsite Coulomb repulsion is large or the electron kinetic energy is
small. The former is the dominant effect in the cuprate superconductors or
heavy fermion systems while the latter in twisted bilayer graphene or
geometrically frustrated metals. However, the simultaneous cooperation of both
effects in the same quantum material--the design principle to produce a
correlated topological flat bands pinned at the Fermi level--remains rare.
Here, using angle-resolved photoemission spectroscopy, we report the
observation of a flat band at the Fermi level in a 3 pyrochlore metal
CuVS. From a combination of first-principles calculations and
slave-spin calculations, we understand the origin of this band to be a
destructive quantum-interference effect associated with the V pyrochlore
sublattice and further renormalization to the Fermi level by electron
interactions in the partially filled V orbitals. As a result, we find
transport behavior that indicates a deviation from Fermi-liquid behavior as
well as a large Sommerfeld coefficient. Our work demonstrates the pathway into
correlated topology by constructing and pinning correlated flat bands near the
Fermi level out of a pure -electron system by the combined cooperation of
local Coulomb interactions and geometric frustration in a pyrochlore lattice
system.Comment: 23 pages, 4 figures, to appear in Nature Physic
Three-Dimensional Flat Bands and Dirac Cones in a Pyrochlore Superconductor
Emergent phases often appear when the electronic kinetic energy is comparable
to the Coulomb interactions. One approach to seek material systems as hosts of
such emergent phases is to realize localization of electronic wavefunctions due
to the geometric frustration inherent in the crystal structure, resulting in
flat electronic bands. Recently, such efforts have found a wide range of exotic
phases in the two-dimensional kagome lattice, including magnetic order,
time-reversal symmetry breaking charge order, nematicity, and
superconductivity. However, the interlayer coupling of the kagome layers
disrupts the destructive interference needed to completely quench the kinetic
energy. Here we experimentally demonstrate that an interwoven kagome network--a
pyrochlore lattice--can host a three dimensional (3D) localization of electron
wavefunctions. In particular, through a combination of angle-resolved
photoemission spectroscopy, fundamental lattice model and density functional
theory (DFT) calculations, we present the novel electronic structure of a
pyrochlore superconductor, CeRu. We find striking flat bands with
bandwidths smaller than 0.03 eV in all directions--an order of magnitude
smaller than that of kagome systems. We further find 3D gapless Dirac cones
predicted originally by theory in the diamond lattice space group with
nonsymmorphic symmetry. Our work establishes the pyrochlore structure as a
promising lattice platform to realize and tune novel emergent phases
intertwining topology and many-body interactions.Comment: 12 pages, 3 figure
Reversible Non-Volatile Electronic Switching in a Near Room Temperature van der Waals Ferromagnet
The ability to reversibly toggle between two distinct states in a
non-volatile method is important for information storage applications. Such
devices have been realized for phase-change materials, which utilizes local
heating methods to toggle between a crystalline and an amorphous state with
distinct electrical properties. To expand such kind of switching between two
topologically distinct phases requires non-volatile switching between two
crystalline phases with distinct symmetries. Here we report the observation of
reversible and non-volatile switching between two stable and closely-related
crystal structures with remarkably distinct electronic structures in the near
room temperature van der Waals ferromagnet FeGeTe. From a
combination of characterization techniques we show that the switching is
enabled by the ordering and disordering of an Fe site vacancy that results in
distinct crystalline symmetries of the two phases that can be controlled by a
thermal annealing and quenching method. Furthermore, from symmetry analysis as
well as first principle calculations, we provide understanding of the key
distinction in the observed electronic structures of the two phases:
topological nodal lines compatible with the preserved global inversion symmetry
in the site-disordered phase, and flat bands resulting from quantum destructive
interference on a bipartite crystaline lattice formed by the presence of the
site order as well as the lifting of the topological degeneracy due to the
broken inversion symmetry in the site-ordered phase. Our work not only reveals
a rich variety of quantum phases emergent in the metallic van der Waals
ferromagnets due to the presence of site ordering, but also demonstrates the
potential of these highly tunable two-dimensional magnets for memory and
spintronics applications
Effects of Aerobic Exercise Training on the Growth, Swimming Performance, Antipredation Ability and Immune Parameters of Juvenile Rock Carp (Procypris rabaudi)
Many studies have found that aerobic exercise training at a moderate water velocity can improve the growth, swimming performance and survival rate of fish. To investigate the effects of aerobic exercise training on the growth, swimming performance, antipredation ability and immune parameters of rock carp, juveniles were placed in training channels with different water velocities (i.e., 3 cm s−1, 1 (body length s−1) bl s−1, 2 bl s−1 and 4 bl s−1) for 6 weeks. Then, the specific growth rate, critical swimming speed (Ucrit) and its metabolism, constant acceleration speed (Ucat), survival rate under predation, spleen index, lysozyme (LZM) activity and immunoglobulin (IgM) level were measured. Training showed no significant effect on the length-specific growth rate, weight-specific growth rate, Ucrit, maximum metabolic rate (MMR), metabolic scope (MS), Ucat or spleen index. The resting metabolic rates (RMRs) of the 2 bl s−1 and 4 bl s−1 training groups were significantly higher than those of the control group and 1 bl s−1 training group. The survival rate of the 1 bl s−1 training group in the presence of predators was significantly higher than that of the control group but significantly lower than those of the 2 bl s−1 and 4 bl s−1 training groups. The LZM activity of the 4 bl s−1 training group was significantly higher than that of the control group. The IgM level of the 2 bl s−1 training group was significantly higher than that of the control group. These data indicate that aerobic exercise training does not improve the growth and swimming performance of juvenile rock carp but can improve their antipredation ability and immunologic function
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Reversible non-volatile electronic switching in a near-room-temperature van der Waals ferromagnet.
Non-volatile phase-change memory devices utilize local heating to toggle between crystalline and amorphous states with distinct electrical properties. Expanding on this kind of switching to two topologically distinct phases requires controlled non-volatile switching between two crystalline phases with distinct symmetries. Here, we report the observation of reversible and non-volatile switching between two stable and closely related crystal structures, with remarkably distinct electronic structures, in the near-room-temperature van der Waals ferromagnet Fe5-δGeTe2. We show that the switching is enabled by the ordering and disordering of Fe site vacancies that results in distinct crystalline symmetries of the two phases, which can be controlled by a thermal annealing and quenching method. The two phases are distinguished by the presence of topological nodal lines due to the preserved global inversion symmetry in the site-disordered phase, flat bands resulting from quantum destructive interference on a bipartite lattice, and broken inversion symmetry in the site-ordered phase