Effects of water stress on nutrients and enzyme activity in rhizosphere soils of greenhouse grape.

In grape cultivation, incorrect water regulation will lead to significant water wastage, which in turn will change soil structure and disrupt soil nutrient cycling processes. This study aimed to investigate the effects of different water regulation treatments [by setting moderate water stress (W1), mild water stress (W2), and adequate water availability (CK)] on soil physical-chemical properties and enzyme activity in greenhouse grape during the growing season. The result showed that the W2 treatment had a negative impact on the build-up of dissolved organic carbon (DOC), nitrate nitrogen (NO3-N), and available phosphorus (AP). Throughout the reproductive period, the W1 and W2 treatments decreased the soil's microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) contents, and MBC was more vulnerable to water stress. During the growth period, the trends of urease, catalase, and sucrase activities in different soil depth were ranked as 10-20 cm > 0-10 cm > 20-40 cm. The urease activity in 0-10 cm soil was suppressed by both W1 and W2 treatments, while the invertase activity in various soil layers under W1 treatment differed substantially. The W1 treatment also reduced the catalase activity in the 20-40 cm soil layer in the grape growth season. These findings suggested that W2 treatment can conserve water and enhance microbial ecology of greenhouse grape soils. Therefore, W2 treatment was the most effective water regulation measure for local greenhouse grape cultivation.

All-inorganic perovskite solar cells featuring mixed group IVA cations.

All-inorganic perovskites are promising for solar cells owing to their potentially superior tolerance to environmental factors, as compared with their hybrid organic-inorganic counterparts. Over the past few years, all-inorganic perovskite solar cells (PSCs) have seen a dramatic improvement in certified power conversion efficiencies (PCEs), demonstrating their great potential for practical applications. Pb, Sn, and Ge are the most studied group IVA elements for perovskites. These group IVA cations share the same number of valence electrons and similarly exhibit the beneficial antibonding properties of lone-pair electrons when incorporated in the perovskite structure. Meanwhile, mixing these cations in all-inorganic perovskites provides opportunities for stabilizing the photoactive phase and tailoring the bandgap structure. In this mini-review, we analyze the structural and bandgap design principles for all-inorganic perovskites featuring mixed group IVA cations, discuss the updated progress in the corresponding PSCs, and finally provide perspectives on future research efforts faciliating the continued development of high-performance Pb-less and Pb-free all-inorganic PSCs.

Boosting the Zn-ion energy storage capability of graphene sandwiched nanoporous VOx derived from MXene.

Aqueous rechargeable zinc-ion batteries (ZIBs) are emerging in grid energy storage due to zinc abundance and intrinsic safety. However, developing suitable cathode materials with satisfactory stability and rate capacity remains a great challenge. Herein, a structure of layered MXene derived nanoporous VOx wrapped with graphene nanosheets (rGO-VOx) is constructed as a cathode for ZIBs. The incorporation of two typical 2D materials imparts composites with shortened diffusion pathways and increased electrical conductivity. Thus, the rGO-VOx cathode exhibits a remarkable rate capability of 196 mA h g-1 at 8 A g-1 and long-term stability with 90% retention after over 1200 cycles at 5 A g-1 in an aqueous coin cell. The Zn storage mechanism is also systematically investigated. The layered V2O5 transforms into layered ZnxV2O5·nH2O with larger interspacing upon cycling. NaV6O15 and the in situ formed ZnxV2O5·nH2O co-contribute to the subsequent insertion and extraction process.

Silicene/poly(N-isopropylacrylamide) smart hydrogels as remote light-controlled switches.

Smart hydrogels with good flexibility and biocompatibility have been widely used. The common near-infrared (NIR) photothermal agents are facing a trade-off between good photothermal-conversion efficiency and high biocompatibility. Therefore, developing new metal-free photothermal agents with low cost, high biocompatibility and excellent phase stability is still in urgent need. In this study, we successfully combined poly(N-isopropylacrylamide) (PNIPAM) with the two-dimensional (2D) silicene nanosheets via the in situ polymerization method. Attributed to the thermal-responsive nature of PNIPAM and the excellent photothermal properties of 2D silicene, the obtained silicene/PNIPAM composite hydrogels exhibited dual thermal and NIR responsive properties. This smart hydrogel showed rapid, reversible and repeatable NIR light-responsive behaviors. The volume of this smart hydrogels can shrink significantly under NIR irradiation and recover to its original size without the NIR irradiation. Remote near-infrared light-controlled microfluidic pipelines and electronic switches based on obtained silicene/PNIPAM composite hydrogels were also demonstrated. This work significantly broadens the application prospects of silicene-based hydrogels in remote light-controlled devices.

Surface Phase Engineering Modulated Iron-Nickel Nitrides/Alloy Nanospheres with Tailored d-Band Center for Efficient Oxygen Evolution Reaction.

The oxygen evolution reaction (OER) plays a key role in many electrochemical energy conversion systems, but it is a kinetically sluggish reaction and requires a large overpotential to deliver appreciable current, especially for the non-noble metal electrocatalysts. In this study, the authors report a surface phase engineering strategy to improve the OER performance of transition metal nitrides (TMNs). The iron-nickel nitrides/alloy nanospheres (FeNi3 -N) wrapped in carbon are synthesized, and the optimized FeNi3 -N catalyst displays dual-phase nitrides on the surface induced by atom migration phenomenon, resulting from the different migration rates of metal atoms during the nitridation process. It shows excellent OER performance in alkaline media with an overpotential of 222 mV at 10 mA cm-2 , a small Tafel slope of 41.53 mV dec-1 , and long-term durability under high current density (>0.5 A cm-2 ) for at least 36 h. Density functional theory (DFT) calculations further reveal that the dual-phase nitrides are favorable to decrease the energy barrier, modulate the d-band center to balance the absorption and desorption of the intermediates, and thus promote the OER electrochemical performance. This strategy may shed light on designing OER and other catalysts based on surface phase engineering.

Carbon Isotope Fractionation Characteristics of Normally Pressured Shale Gas from the Southeastern Margin of the Sichuan Basin; Insights into Shale Gas Storage Mechanisms.

Since the development of shale gas in the Wufeng-Longmaxi Formation in the Sichuan Basin, China's shale gas production and reserves have increased rapidly. The southeastern margin of the Sichuan Basin is located in a normally pressured transition zone, where single well gas production varies greatly under complex geological structures. In order to reveal the shale gas enrichment mechanism and favorable shale gas regions, shale gas samples from production wells were collected from different structures, with the formation pressure coefficient ranging between 0.98 and 1.35. The gas components and carbon isotope characteristics of normally pressured shale gas were investigated. The carbon isotope characteristics of the Wufeng-Longmaxi shale gas from the basin scale was mainly controlled using thermal maturity; as the thermal maturity increased, heavier carbon isotopes were found, in addition to drier shale gas. For normally pressured shale gas, the composition of δ13C1 and δ13C2 becomes heavier, and the dryness coefficient decreases with the decreasing pressure coefficient; this is not consistent with the results from thermal evolution. By comparing possible influencing factors, it is evident that the change in geological structure destroys the original shale gas reservoir, which leads to the escape of some gases, and it may be the main factor that contributes to the gas geochemical characteristics of the normally pressured shale gas. Compared with the geological parameters of the shale samples, such as mineral composition, organic abundance, organic pore distribution, and gas content, the carbon isotope characteristics of normally pressured shale gas show a higher efficiency, thus indicating favorable sweet spot evaluations for shale gas in the studied areas.

[Spectrum characteristics of habitat quality changes in Gansu Province, China]. / 甘肃省生境质量变化的图谱特征.

Habitat quality is an important factor affecting regional ecosystem service value and protecting the biodiversity of the earth. Gansu Province is located in the intersection of the three nature areas in China. On the basis of quantitative estimation of the regional habitat quality in Gansu during 2000 to 2018, based on the spectrum change analysis theory and InVEST model, we explored the spatio-temporal differentiation pattern of the regional habitat quality status and its spectrum transformation and change intensity. The results showed that the habitat quality of Gansu Province generally maintained a middle level and improved slightly, showing a step-by-step change from the north to south in the spatial distribution, with the coexistence of both high and low habitat quality. The structure of habitat quality in Gansu Province was stable based on the view of the spectrum transformation, and the spectrum units which did not appear state transition were dominant in quantity. The transition of each other of those spectrum units which had occurred transition of the habitat quality, such as higher  lower, higher  high, higher  low was most obvious, with the spatial distribution in aggregation. The change intensity of habitat quality in Gansu Province presented a general tendency with active in the north and moderate in the south, presenting as active intensity area, complex intensity area, moderate intensity area, and slight intensity area from the north to south.

Correction: Ti2C3Tx nanosheets as photothermal agents for near-infrared responsive hydrogels.

Correction for 'Ti2C3Tx nanosheets as photothermal agents for near-infrared responsive hydrogels' by Changyu Yang et al., Nanoscale, 2018, 10, 15387-15392.

Ti2C3Tx nanosheets as photothermal agents for near-infrared responsive hydrogels.

Poly(N-isopropylacrylamide) (PNIPAM) is broadly applicable in many fields due to its temperature-induced phase transition property. Herein, a facile method to incorporate exfoliated Ti2C3Tx nanosheets in the PNIPAM network is reported. Due to compatibility, stability and photothermal properties of the incorporated Ti2C3Tx nanosheets, the obtained MXene/PNIPAM composite hydrogel shows excellent photothermal properties, expanding the pure thermal-responsive property of the PNIPAM hydrogel. Based on the smart composite hydrogel, remote light-control of the microfluidic pipeline is also demonstrated.

Theoretical prediction of new noble-gas molecules FNgBNR (Ng = Ar, Kr, and Xe; R = H, CH3, CCH, CHCH2, F, and OH).

We have computationally predicted a new class of stable noble-gas molecules FNgBNR (Ng = Ar, Kr, Xe; R = H, CH3, CCH, CHCH2, F, and OH). The FNgBNR were found to have compact structures with F-Ng bond lengths of 1.9-2.2 Å and Ng-B bond lengths of ~1.8 Å. The endoergic three-body dissociation energies of FNgBNH to F + Ng + BNH were calculated to be 12.8, 31.7, and 63.9 kcal mol(-1), for Ng = Ar, Kr, and Xe, respectively at the CCSD(T)/CBS level. The energy barriers of the exoergic two-body dissociation to Ng + FBNH were calculated to be 16.1, 24.0, and 33.2 kcal mol(-1) for Ng = Ar, Kr, and Xe, respectively. Our results showed that the dissociation energetics is relatively insensitive to the identities of the terminal R groups. The current study suggested that a wide variety of noble-gas containing molecules with different types of R groups can be thermally stable at low temperature, and the number of potentially stable noble-gas containing molecules would thus increase very significantly. It is expected some of the FNgBNR molecules could be identified in future experiments under cryogenic conditions in noble-gas matrices or in the gas phase.

Theoretical prediction on the structures and stability of the noble-gas containing anions FNgCC- (Ng=He, Ar, Kr, and Xe).

We have made high-level theoretical study on a new type of noble-gas (Ng) containing anions FNgCC(-). The calculated short Ng-CC bond lengths of 1.13, 1.77, 1.89, and 2.04 Šfor Ng=He, Ar, Kr, and Xe, respectively, and the electron density distributions indicated strong covalent interactions between the Ng and CC induced by the polarizing fluoride ion. Except for FHeCC(-), the structures of all other FNgCC(-) were predicted to be linear. The intrinsic stability of the FNgCC(-) was studied by calculating the energies of the three-body dissociation reaction: FNgCC(-) → F(-) + Ng + CC and by calculating the energy barriers of the two-body dissociation reaction: FNgCC(-) → Ng + FCC(-). The results showed that FNgCC(-) (Ng=Ar, Kr, Xe) could be kinetically stable in the gas phase with the three-body dissociation energies of 17, 37, and 64 kcal/mol and two body-dissociation barriers of 22, 31, and 42 kcal/mol, respectively, at the coupled-cluster single double (triple)/aug-cc-pVQZ level of theory. The structures and the stability were also confirmed using the multi-reference CASPT2 calculation. Future experimental identification of the FNgCC(-) anions is expected under cryogenic conditions.

Benchmark of density functional theory methods on the prediction of bond energies and bond distances of noble-gas containing molecules.

We have tested three pure density functional theory (DFT) functionals, BLYP, MPWPW91, MPWB95, and ten hybrid DFT functionals, B3LYP, B3P86, B98, MPW1B95, MPW1PW91, BMK, M05-2X, M06-2X, B2GP-PLYP, and DSD-BLYP with a series of commonly used basis sets on the performance of predicting the bond energies and bond distances of 31 small neutral noble-gas containing molecules. The reference structures were obtained using the CCSD(T)∕aug-cc-pVTZ theory and the reference energies were based on the calculation at the CCSD(T)∕CBS level. While in general the hybrid functionals performed significantly better than the pure functionals, our tests showed a range of performance by these hybrid functionals. For the bond energies, the MPW1B95∕6-311+G(2df,2pd), BMK∕aug-cc-pVTZ, B2GP-PLYP∕aug-cc-pVTZ, and DSD-BLYP∕aug-cc-pVTZ methods stood out with mean unsigned errors of 2.0-2.3 kcal∕mol per molecule. For the bond distances, the MPW1B95∕6-311+G(2df,2pd), MPW1PW91∕6-311+G(2df,2pd), and B3P86∕6-311+G(2df,2pd), DSD-BLYP∕6-311+G(2df,2pd), and DSD-BLYP∕aug-cc-pVTZ methods stood out with mean unsigned errors of 0.008-0.013 Å per bond. The current study showed that a careful selection of DFT functionals is very important in the study of noble-gas chemistry, and the most recommended methods are MPW1B95∕6-311+G(2df,2pd) and DSD-BLYP∕aug-cc-pVTZ.

Analysis of olfactory ensheathing glia transplantation-induced repair of spinal cord injury by electrophysiological, behavioral, and histochemical methods in rats.

This study examined the efficacy of transplanting olfactory ensheathing glia (OEG) in repairing spinal cord injury (SCI) using behavioral tests, retrograde labeling, as well as somatosensory and motor evoked potentials in rats. One week after surgery, motor function in OEG-treated rats was significantly superior to untreated controls (P < 0.05). Also, we found that up to 8 weeks following surgery to induce SCI, somatosensory and motor evoked potentials were found in the OEG-treated groups, but not in the transplantation and damage control groups. Retrograde labeling from the area distal to the SCI produced a higher number of labeled neurons in the ventrolateral division of red nucleus and motor cortex of OEG-treated rats compared to controls, which showed no retrograde labeling (P < 0.05). We believe that this study has important implications for characterizing the mechanisms of OEG transplantation as a treatment for SCI.

[The Predictive Role of Vascular Endothelial Growth Factor and Estradiol in Infertile Patients with Ovarian Hyperstimulation Syndrome].

OBJECTIVE: To determine the predictive values of vascular endothelial growth factor (VEGF) and estradiol (E2) in patients with ovarian hyperstimulation syndrome (OHSS) and to go further into the relevant pathogenisis. METHODS: Blood samples were collected from 51 high risk patients and 30 control patients undergoing superovulation on the day of hCG administration and follicular fluid at the time of egg retrieval. The high risk patients were divided into two groups[OHSS group (n=11) and non-OHSS group (n=40)] VEGF and E2 were detected and then differences between the high risk groups and control group were analyzed. RESULTS: There wa no significant difference in VEGF between high risk groups and control group on the day of hCG injection (P>0.05). After hCG administration, serum VEGF concentrations rose significantly in OHSS group (P<0.01). The serum and follicular fluid VEGF levels were obviously higher than those of the control group. The follicular fluid concentrations of VEGF were significantly higher than that of serum in every group (P<0.001). E2 concentrations of OHSS group rose obviously after hCG injection (P<0.01) and were significantly higher than those of the control group (P<0.01), but there no statistically significant change in E2 concentrations in non-OHSS groups (P>0.05). CONCLUSION: The results from this study show that the serum and follicular fluid VEGF concentrations are significantly higher than those of control group on the day of ovum retrieval, indicating that VEGF may play an important role in the pathogenesis of OHSS. It cannot predict the risk of OHSS on the day hCG administration, but it may be considered as a predictive marker for the development of OHSS after hCG administration. Serum VEGF concentrations in combination with consective E2 measurements can assist in predicting OHSS.

Volatile organic profiles and photochemical potentials from motorcycle engine exhaust.

This study surveyed emissions from 2- and 4-stroke new and in-use motorcycles. Emission tests were carried out on a dynamometer following the designated test procedure of the Economic Commission for Europe (ECE). Samples were derived during various driving stages, which included idle, acceleration, 30 km/hr cruise, 50 km/hr cruise, and deceleration. All test motorcycles (10 new and 15 in-use) complied with Taiwan Environmental Protection Administration's Phase III Motorcycle Emission Standards. The dominant volatile organic carbon (VOC) species were isopentane (53 and 295 mg/km, 2- and 4-stroke, respectively), 2-methylpentane (75 and 83 mg/km), 3-methylpentane (34 and 66 mg/km), and toluene (30 and 100 mg/km). The VOC emission factors for the 2-/4-stroke motorcycles were 311/344 (new) and 1479/433 (in-use) mg/km, respectively. In addition, the dominant carbonyl species for the new and in-use motorcycles were formaldehyde (0.4 and 0.7 mg/km, respectively), acetaldehyde (0.6 and 1.2 mg/km), and acetone (0.5 and 0.7 mg/km). The carbonyl compound emission factors for the 2- and 4-stroke motorcycles were 3.2/3.1 (new) and 5.3/4.6 (in-use) mg/km, respectively. The ozone formation potentials, based on an ECE test cycle, show that the values from the in-use motorcycles were higher than those from the new motorcycles. The dominant VOC species for the ozone formation potential were propylene (65 and 502 mg-O3/km, respectively), isopentane (98 and 501 mg-O3/km), 2-methylpentane (152 and 167 mg-O3/ km), 3-methylpentane (79 and 253 mg-O3/km), and toluene (127 and 398 mg-O3/km). Further, the dominant carbonyl species were formaldehyde (4.1 and 6.2 mg-O3/ km, new and in-use, respectively) and acetaldehyde (4.8 and 9 mg-O3/km).