Green Manuring Enhances Soil Multifunctionality in Tobacco Field in Southwest China.

The use of green manure can substantially increase the microbial diversity and multifunctionality of soil. Green manuring practices are becoming popular for tobacco production in China. However, the influence of different green manures in tobacco fields has not yet been clarified. Here, smooth vetch (SV), hairy vetch (HV), broad bean (BB), common vetch (CV), rapeseed (RS), and radish (RD) were selected as green manures to investigate their impact on soil multifunctionality and evaluate their effects on enhancing soil quality for tobacco cultivation in southwest China. The biomass of tobacco was highest in the SV treatment. Soil pH declined, and soil organic matter (SOM), total nitrogen (TN), and dissolved organic carbon (DOC) content in CV and BB and activity of extracellular enzymes in SV and CV treatments were higher than those in other treatments. Fungal diversity declined in SV and CV but did not affect soil multifunctionality, indicating that bacterial communities contributed more to soil multifunctionality than fungal communities. The abundance of Firmicutes, Rhizobiales, and Micrococcales in SV and CV treatments increased and was negatively correlated with soil pH but positively correlated with soil multifunctionality, suggesting that the decrease in soil pH contributed to increases in the abundance of functional bacteria. In the bacteria-fungi co-occurrence network, the relative abundance of key ecological modules negatively correlated with soil multifunctionality and was low in SV, CV, BB, and RS treatments, and this was associated with reductions in soil pH and increases in the content of SOM and nitrate nitrogen (NO3--N). Overall, we found that SV and CV are more beneficial for soil multifunctionality, and this was driven by the decrease in soil pH and the increase in SOM, TN, NO3--N, and C- and N-cycling functional bacteria.

Resolved magnetohydrodynamic wave lensing in the solar corona.

Electromagnetic wave lensing, a common physical phenomenon recognized in visible light for centuries, finds extensive applications in manipulating light in optical systems such as telescopes and cameras. Magnetohydrodynamic wave is a common perturbation phenomenon in the corona. By using high spatio-temporal resolution observations from the Solar Dynamics Observatory, here, we report the observation of a magnetohydrodynamic wave lensing in the highly ionized and magnetized coronal plasma, where quasi-periodic wavefronts emanated from a flare converged at a specific point after traversing a coronal hole. The entire process resembles an electromagnetic wave lensing from the source to the focus. Meanwhile, the magnetohydrodynamic wave lensing is well reproduced through a magnetohydrodynamic numerical simulation with full spatio-temporal resolution. We further investigate potential applications for coronal seismology, as the lensing process encodes information on the Alfvén speed, in conjunction with favorable geometric and density variations.

In Situ Atomic-Scale Quantitative Evidence of Plastic Activities Resulting in Reparable Deformation in Ultrasmall-Sized Ag Nanocrystals.

Permanent structural changes in pure metals that are caused by plastic activity are normally irreparable after unloading. Because of the lack of experimental evidence, it is unclear whether the plastic activity can be repaired as the size of the pure metals decreases to several nanometers; it is also unclear how the metals accommodate the plastic deformation. In this study, the in situ atomic-scale loading and unloading of ∼2 nm Ag nanocrystals was investigated, and three modes of plastic deformation were observed: (i) the phase transition from the face-centered cubic (fcc) phase to the hexagonal close-packed (hcp) phase, (ii) stacking faults, and (iii) deformation twin nucleation. We show that all three modes resulted in structural changes that were reparable, and their generation and restoration during loading and unloading were observed in situ. We discovered that the deformation modes of nanosized metals can be predicted from the ratio of the energy barriers of the fcc-hcp phase transition (ΔγH) and the deformation twin nucleation (ΔγT), which differ from those of the theoretical modes of relatively large-sized metals. The proposed ΔγH/ΔγT criterion provides insights into the deformation mechanism of nanometals.

Interaction between dissolved organic carbon and fungal network governs carbon mineralization in paddy soil under co-incorporation of green manure and biochar.

Legume crops in rice cultivation are typically rotated and incorporated into the soil as green manure to improve soil fertility. Biochar has recently been co-incorporated with green manure to simultaneously stimulate soil organic carbon (SOC) mineralization and increase carbon (C) sequestration. However, few studies examine the effects of the co-incorporation of biochar and green manure on C cycling and the underlying microbial mechanisms in paddy fields. In this study, the effects of the co-incorporation of green manure and biochar on C mineralization, dissolved organic carbon (DOC) characteristics, and microbial community structures were investigated. A pot study was conducted with three treatments: inorganic NPK (NPK), inorganic NPK + green manure (GM), and inorganic NPK + green manure + biochar (GMC). Organic amendments significantly increased cumulative C mineralization, with amounts in the order GMC (3,434 mg·kg-1) > GM (2,934 mg·kg-1) > NPK (2,592 mg·kg-1). Fertilizer treatments had similar effects on DOC concentrations, with amounts in the order GMC (279 mg·kg-1) > GM (255 mg·kg-1) > NPK (193 mg·kg-1). According to fluorescence spectra, the highest microbial humic acid-like fraction and biological index were also in GMC. Co-incorporation of green manure and biochar shifted the composition of bacterial and fungal communities but more importantly, increased fungal network complexity and decreased bacterial network complexity. The increase in fungal network complexity with the increase in DOC concentrations and microbially derived components was the dominant factor in promoting C mineralization. Overall, this study reveals the underlying biochemical mechanism, the interaction between DOC and fungal network of C cycling in paddy soil under the co-incorporation of green manure and biochar management, and provides fundamental knowledge for exploring effective approaches to improve soil fertility and health in the future.

Chemical inhomogeneity-induced profuse nanotwinning and phase transformation in AuCu nanowires.

Nanosized metals usually exhibit ultrahigh strength but suffer from low homogeneous plasticity. The origin of a strength-ductility trade-off has been well studied for pure metals, but not for random solid solution (RSS) alloys. How RSS alloys accommodate plasticity and whether they can achieve synergy between high strength and superplasticity has remained unresolved. Here, we show that face-centered cubic (FCC) RSS AuCu alloy nanowires (NWs) exhibit superplasticity of ~260% and ultrahigh strength of ~6 GPa, overcoming the trade-off between strength and ductility. These excellent properties originate from profuse hexagonal close-packed (HCP) phase generation (2H and 4H phases), recurrence of reversible FCC-HCP phase transition, and zigzag-like nanotwin generation, which has rarely been reported before. Such a mechanism stems from the inherent chemical inhomogeneity, which leads to widely distributed and overlapping energy barriers for the concurrent activation of multiple plasticity mechanisms. This naturally implies a similar deformation behavior for other highly concentrated solid-solution alloys with multiple principal elements, such as high/medium-entropy alloys. Our findings shed light on the effect of chemical inhomogeneity on the plastic deformation mechanism of solid-solution alloys.

30-min decayless kink oscillations in a very long bundle of solar coronal plasma loops.

The energy balance in the corona of the Sun is the key to the long-standing coronal heating dilemma, which could be potentially revealed by observational studies of decayless kink oscillations of coronal plasma loops. A bundle of very long off-limb coronal loops with the length of [Formula: see text] Mm and a lifetime of about 2 days are found to exhibit decayless kink oscillations. The oscillations are observed for several hours. The oscillation amplitude is measured at 0.3-0.5 Mm, and the period at 28-33 min. The existence of 30-min periodicity of decayless kink oscillations indicates that the mechanism compensating the wave damping is still valid in such a massive plasma structure. It provides important evidence for the non-resonant origin of decayless kink oscillations with 2-6 min periods, i.e., the lack of their link with the leakage of photospheric and chromospheric oscillations into the corona and the likely role of the broadband energy sources. Magnetohydrodynamic seismology based on the reported detection of the kink oscillation, with the assistance of the differential emission measure analysis and a background coronal model provides us with a comprehensive set of plasma and magnetic field diagnostics, which is of interest as input parameters of space weather models.

Transverse oscillations and an energy source in a strongly magnetized sunspot.

The solar corona is two to three orders of magnitude hotter than the underlying photosphere, and the energy loss of coronal plasma is extremely strong, requiring a heating flux of over 1,000 W m-2 to maintain its high temperature. Using the 1.6 m Goode Solar Telescope, we report a detection of ubiquitous and persistent transverse waves in umbral fibrils in the chromosphere of a strongly magnetized sunspot. The energy flux carried by these waves was estimated to be 7.52 × 106 W m-2, three to four orders of magnitude stronger than the energy loss rate of plasma in active regions. Two-fluid magnetohydrodynamic simulations reproduced the high-resolution observations and showed that these waves dissipate significant energy, which is vital for coronal heating. Such transverse oscillations and the associated strong energy flux may exist in a variety of magnetized regions on the Sun, and could be the observational target of next-generation solar telescopes.

Direct Atomic-Scale Observation of Ultrasmall Ag Nanowires that Exhibit fcc, bcc, and hcp Structures under Bending.

Metals usually have three crystal structures: face-centered cubic (fcc), body-centered cubic (bcc), and hexagonal-close packed (hcp) structures. Typically, metals exhibit only one of these structures at room temperature. Mechanical processing can cause phase transition in metals, however, metals that exhibit all the three crystal structures have rarely been approached, even when hydrostatic pressure or shock conditions are applied. Here, through in situ observation of the atomic-scale bending and tensile process of ∼5 nm-sized Ag nanowires (NWs), we show that bending is an effective method to facilitate fcc-structured Ag to access all the above-mentioned structures. The process of transitioning the fcc structure into a bcc structure, then into an hcp structure, and finally into a re-oriented fcc structure under bending has been witnessed in its entirety. This re-oriented fcc structure is twin-related to the matrix, which leads to twin nucleation without the need for partial dislocation activities. The results of this study advance our understanding of the deformation mechanism of small-sized fcc metals.

Deformation-Induced Phase Transformations in Gold Nanoribbons with the 4H Phase.

The mechanical stability of metallic nanomaterials has been intensively studied due to their unique structures and promising applications. Although extensive investigations have been carried out on the deformation behaviors of metallic nanomaterials, the atomic-scale deformation mechanism of metallic nanomaterials with unconventional hexagonal structures remains unclear because of the lack of direct experimental observation. Here, we conduct an atomic-resolution in situ tensile-straining transmission electron microscopy investigation on the deformation mechanism of gold nanoribbons with the 4H (hexagonal) phase. Our results reveal that plastic deformation in the 4H gold nanoribbons comprises three stages, in which both full and partial dislocations are involved. At the early deformation stage, plastic deformation is governed by full dislocation activities. Partial dislocations are subsequently activated in regions that have undergone full dislocation gliding, leading to phase transformation from the 4H phase to the face-centered cubic (FCC) phase. At the last stage of the deformation process, the volume fraction of the FCC phase increases, and full dislocation activities in the FCC regions also play an important role.

Enhanced negative magnetoresistance near the charge neutral point in Cr doped topological insulator.

Negative magnetoresistance (MR) is not only of great fundamental interest for condensed matter physics and materials science, but also important for practical applications, especially magnetic data storage and sensors. However, the microscopic origin of negative MR is still elusive and the nature of the negative MR in magnetic topological insulators has still not been completely elucidated. Here, we report magnetotransport studies on Cr doped (Bi1-x Sb x )2Te3 topological insulator thin films grown by magnetron sputtering. At the temperature of 2 K, a giant negative MR reaching 61% is observed at H = 2 T. We show that the negative MR is closely related to the position of the Fermi level, and it reaches the maximum when the Fermi level is gated near the charge neutral point. We attribute these results to the Coulomb potential due to the random composition fluctuations in Cr doped (Bi1-x Sb x )2Te3. Our results provide a deeper insight into the mechanism of negative MR, and are helpful to realize the quantum anomalous Hall effect in the sputtered Cr-(Bi1-x Sb x )2Te3 thin-film systems by tuning the Fermi level and reducing disorder effects.

In situ atomic-scale observation of grain size and twin thickness effect limit in twin-structural nanocrystalline platinum.

Twin-thickness-controlled plastic deformation mechanisms are well understood for submicron-sized twin-structural polycrystalline metals. However, for twin-structural nanocrystalline metals where both the grain size and twin thickness reach the nanometre scale, how these metals accommodate plastic deformation remains unclear. Here, we report an integrated grain size and twin thickness effect on the deformation mode of twin-structural nanocrystalline platinum. Above a ∼10 nm grain size, there is a critical value of twin thickness at which the full dislocation intersecting with the twin plane switches to a deformation mode that results in a partial dislocation parallel to the twin planes. This critical twin thickness value varies from ∼6 to 10 nm and is grain size-dependent. For grain sizes between ∼10 to 6 nm, only partial dislocation parallel to twin planes is observed. When the grain size falls below 6 nm, the plasticity switches to grain boundary-mediated plasticity, in contrast with previous studies, suggesting that the plasticity in twin-structural nanocrystalline metals is governed by partial dislocation activities.

Antinociceptive effects induced by intra-lateral habenula complex injection of the galanin receptor 1 agonist M617 in rats.

The present study was performed to explore the antinociceptive effects of the galanin receptor 1 agonist M617 in lateral habenula complex in rats. Intra-lateral habenula injection of 0.1, 0.5, 1 or 2 nmol of galanin induced dose-dependent increases in hindpaw withdrawal latencies (HWLs) to noxious thermal and mechanical stimulations in rats. Furthermore, intra-lateral habenula injection of 0.1, 0.5, 1 or 2 nmol of the galanin receptor 1 agonist M617 also induced dose-dependent increases in HWLs to noxious thermal and mechanical stimulations in rats. Interestingly, there were no significant differences between the antinociceptive effects induced by intra-lateral habenula injection of 2 nmol of M617 and 2 nmol of galanin. The results indicate that galanin receptor 1 may be involved in the galanin-induced antinociceptive effects in the lateral habenula.

The participation of oxytocin in the abirritation of lateral habenular nucleus on normal adult rats.

This paper probes into the participation of different concentrations of oxytocin in the pain regulation of lateral habenular nucleus on normal adult rats. The detailed experiment steps are as follows: microinject 1.25, 2.5, and 5nmol of oxytocin to three adult rats׳ lateral habenular nucleus, and measure the hind paw withdrawal latency (HWL) after 5, 10, 15, 20, 30, 45 and 60min with hot plate and pressure plate test as the indicator of algesia. At the same time, another group of adult rats were injected with normal saline as a control to observe the participation of oxytocin in the pain regulation of lateral habenular nucleus. Through the oxytocin microinjection, the HWL of rats was significantly prolonged, compared with the control group. According to the experimental results, the HWL of thermo stimulation on the left paw of the rats between OT group and the control group (injected with normal saline) showed no difference (p>0.05) after a microinjection of 1.25nmol in LHb, while the HWL of thermo stimulation on the left paw of the rats showed significant difference (p<0.01; p<0.01) after a microinjection of 2.5 and 5nmol in LHb; The HWL of thermo stimulation on the right paw of the rats between OT group and the control group (injected with normal saline) showed significant difference, slight difference and significant difference (p<0.01; p<0.05; p<0.01) after a microinjection of 1.25, 2.5 and 5.0nmol in LHb; The HWL of mechanical stimulation both on the left paw of the rats after a microinjection of 2.5nmol and on the right paw of the rats after a microinjection of 5nmol showed significant differences (p<0.01; p<0.01), and all the rest showed extremely significant differences (p<0.001). This experiment shows that oxytocin has significant abirritational effect on the lateral habenular nucleus of adult rats, which is dose dependent, especially after OT was injected for 15min.

Involvement of protein kinase C in the galanin-induced antinociception in the brain of rats.

Previous study in our laboratory demonstrates that microinjection of galanin into the arcuate nucleus of hypothalamus produced antinociceptive effects in rats. In the present study we investigated the involvement of protein kinase C (PKC) and PKC signaling pathways in the galanin-induced antinociception in the brain of rats. Intracerebroventricular injection of galanin produced antinociceptive effects in rats tested by hot-plate and Randall Selitto test. Interestingly, the galanin-induced antinociception was significantly attenuated by intracerebroventricular injection of the PKC inhibitor chelerythrine, indicating an involvement of PKC in the galanin-induced antinociception in rats. Taken together, the results demonstrate that galanin induces antinociceptive effects in the rat brain, and PKC is involved in the galanin-induced antinociception in the brain of rats.

Antinociceptive effects of intracerebroventricular injection of the galanin receptor 1 agonist M 617 in rats.

Previous studies in our laboratory demonstrated that galanin and its receptors play important roles in nociceptive modulation in the central nervous system. The present study was performed to explore the antinociceptive effects of the galanin receptor 1 agonist M 617 in the central nervous system of rats. Intracerebroventricular injection of 0.1nmol, 0.5nmol, 1nmol or 2nmol of M 617 induced dose-dependent increases in hindpaw withdrawal latencies (HWLs) to noxious thermal and mechanical stimulations in rats. Furthermore, both intracerebroventricular injection of M 617 and galanin induced significant increases in HWLs in rats. Interestingly, there were no significant differences between the antinociceptive effects induced by M 617 and galanin, indicating that galanin receptor 1 plays main roles in galanin-induced antinociceptive effects in the brain of rats.

Growth inhibition and apoptosis induction in human hepatoma cells by tanshinone II A.

In order to study the effect of tanshinone II A on growth and apoptosis in human hepatoma cell line BEL-7402 in vitro, the human hepatoma cell line BEL-7402 was treated with tanshinone II A at various concentrations for 72 h. Growth suppression was evaluated by MTT assay; apoptosis-related alterations in morphology and biochemistry were ascertained under cytochemical staining (Hoechst 33258), transmission electron microscopy (TEM), and DNA agarose gel electrophoresis. Apoptotic rate was quantified by flow cytometry (FCM). The results showed that Tanshinone II A could inhibit the growth of hepatoma cells in a dose-dependent manner, with IC50 value being 6.28 micrograms/ml. After treatment with 1-10 micrograms/ml tanshinone II A for 72 h, BEL-7402 cells apoptosis with nuclear chromatin condensation and fragmentation as well as cell shrinkage and the formation of apoptotic bodies were observed. DNA ladder could be demonstrated on DNA electrophoresis. FCM analysis showed hypodiploid peaks on histogram, and the apoptotic rates at 5 micrograms/ml concentration for 12 h, 24 h, 36 h, 48 h and 72 h were (2.32 +/- 0.16)%, (3.01 +/- 0.35)%, (3.87 +/- 0.43)%, (6.73 +/- 0.58)% and (20.85 +/- 1.74)% respectively, which were all significantly higher than those in the control group (1.07 +/- 0.13)%. It is concluded that Tanshinone II A could induce human hepatoma cell line BEL-7402 apoptosis, which may be related to the mechanism of growth inhibition.

[Effect of tanshinone IIA on the growth behavior of human hepatoma cell line BEL-7402 in vitro and its mechanism].

OBJECTIVE: To investigate the effect of tanshinone IIA on the growth behavior of human hepatoma cell line BEL-7402 in vitro and explore the mechanism. METHODS: Human hepatoma cell line BEL-7402 was exposed to tanshinoneIIA at different concentrations for 72 h, and the suppression of the cell growth was observed under inverted-phase contrast microscope. Apoptosis-related alterations in the cell morphology and biochemistry were examined under fluorescence microscope and transmission electron microscope (TEM) and by DNA agarose gel electrophoresis, and the apoptotic rate was quantified by flow cytometry (FCM). RESULTS: After treatment with 0-10 microg/ml tanshinone IIA for 72 h, the proliferation of BEL-7402 cells was significantly suppressed, and cell apoptosis occurred characterized by cell shrinkage, nuclear chromatin condensation and fragmentation, formation of membrane blebs and apoptotic bodies as observed under fluorescence microscope and TEM. DNA ladder was presented in DNA electrophoresis. FCM analysis yielded the cell apoptotic rates of (20.78+/-2.17) %, (24.64+/-2.07) %, (31.47+/-3.86) %, (43.65+/-4.04) % and (52.36+/-3.75) % at tanshinone IIA concentrations of 0.5, 1.0, 2.0, 5.0 and 10.0 microg/ml respectively, all significantly higher than those of the control group [(2.37+/-0.29)%]. CONCLUSION: Tanshinone IIA can inhibit the growth of human hepatoma BEL-7402 cells possibly through the mechanism of apoptosis induction.