Quantitative Proteomics Reveal the Inherent Antibiotic Resistance Mechanism against Norfloxacin Resistance in Aeromonas hydrophila.

Recently, the prevalence of Aeromonas hydrophila antibiotic-resistant strains has been reported in aquaculture, but its intrinsic antibiotic resistance mechanisms are largely unknown. In the present study, a label-free proteomics technology was used to compare the differential protein abundances in response to norfloxacin (NOR) stress in A. hydrophila. The results showed that there were 186 proteins decreasing and 220 proteins increasing abundances in response to NOR stress. Bioinformatics analysis showed that the differentially expressed proteins were enriched in several biological processes, such as sulfur metabolism and homologous recombination. Furthermore, the antibiotic sensitivity assays showed that the deletion of AHA_0904, cirA, and cysI significantly decreased the resistance against NOR, whereas ΔAHA_1239, ΔcysA, ΔcysD, and ΔcysN significantly increased the resistance against NOR. Our results provide insights into NOR resistance mechanisms and indicate that AHA_0904, cirA, AHA_1239, and sulfur metabolism may play important roles in NOR resistance in A. hydrophila.

The effect of switchable electronic polarization states on the electronic properties of two-dimensional multiferroic TMBr2/Ga2SSe2 (TM = V-Ni) heterostructures.

Multiferroic van der Waals (vdW) heterostructures (HSs) prepared by combining different ferroic materials offer an exciting platform for next-generation nanoelectronic devices. In this work, we investigate the magnetoelectric coupling properties of multiferroic vdW HSs consisting of a magnetic TMBr2 (TM = V-Ni) monolayer and a ferroelectric Ga2SSe2 monolayer using first-principles theory calculations. It is found that the magnetic orderings in the magnetic TMBr2 layers are robust and the band alignment of these TMBr2/Ga2SSe2 HSs can be altered by reversing the polarization direction of the ferroelectric layer. Among them, VBr2/Ga2SSe2 and FeBr2/Ga2SSe2 HSs can be switched from a type-I to a type-II semiconductor, which allows the generation of spin-polarized and unpolarized photocurrent. Besides, CrBr2/Ga2SSe2, CoBr2/Ga2SSe2 and NiBr2/Ga2SSe2 exhibit a type-II band alignment in reverse ferroelectric polarization states. Moreover, the magnetic configuration and band alignment of these TMBr2/Ga2SSe2 HSs can be further modulated by applying an external strain. Our findings suggest the potential of TMBr2/Ga2SSe2 HSs in 2D multiferroic and spintronic applications.

Graphene adlayer growth between nonepitaxial graphene and the Ni(111) substrate: a theoretical study.

Understanding the fundamentals of chemical vapor deposition bilayer graphene growth is crucial for its synthesis. By employing density functional theory calculations and classical molecular dynamics simulations, we have investigated the evolution of carbon structures and the kinetics of the adlayer graphene nucleation between the graphene top layer (GTL) and the Ni(111) substrate. Compared to the epitaxial GTL, the weaker interaction between the nonepitaxial GTL and the Ni(111) substrate makes the nucleation of the adlayer more favorable. Furthermore, the defects involving in the adlayer graphene are easier to be healed by adopting the nonepitaxial GTL. Our results agree well with the experimental observation and demonstrate that the adlayer graphene with a high quality can be grown underneath the nonepitaxial GTL on Ni-like substrates.

Ferroelectricity with Asymmetric Hysteresis in Metallic LiOsO_{3} Ultrathin Films.

Bulk LiOsO_{3} was experimentally identified as a "ferroelectric" metal where polar distortions coexist with metallicity [Shi et al., Nat. Mater. 12, 1024 (2013)NMAACR1476-112210.1038/nmat3754]. It is generally believed that polar displacements in a ferroelectric metal cannot be switched by an external electric field. Here, via comprehensive density functional theory calculations, we demonstrate that a two-unit cell-thick LiOsO_{3} thin film exhibits a ferroelectric ground state having an out-of-plane electric dipole moment that can be switched by an external electric field. Moreover, its dipole moment-versus-electric field hysteresis loop is asymmetric because only surface Li ions' displacements are reversed by the external electric field whereas the field-induced force on inner Li atoms is nearly fully screened by itinerant electrons. As a relevant by-product of our study, we also extend the concept of "Born effective charge" to finite metallic systems, and show its usefulness to rationalize the observed effects.

Unusual Ferroelectricity in Two-Dimensional Perovskite Oxide Thin Films.

Two-dimensional (2D) ferroelectricity have attracted much attention due to their applications in novel miniaturized devices such as nonvolatile memories, field effect transistors, and sensors. Since most of the commercial ferroelectric (FE) devices are based on ABO3 perovskite oxides, it is important to investigate the properties of 2D ferroelectricity in perovskite oxide thin films. Here, based on density functional theory (DFT) calculations, we find that there exist three kinds of in-plane FE states that originate from different microscopic mechanisms: (i) a proper FE state with the polarization along [110] due to the second-order Jahn-Teller effect related to the B ion with empty d-orbitals; (ii) a robust FE state with the polarization along [100] induced by the surface effect; (iii) a hybrid improper FE state with the polarization along [110] that is induced by the trilinear coupling between two rotational modes and the A-site displacement. Interestingly, the ferroelectricity in the latter two cases becomes stronger along with decreasing the thin film thickness, in contrast to the usual behavior. Moreover, the latter two FE states are compatible with magnetism since their stability does not depend on the occupation of the d-orbitals of the B-ion. These two novel 2D FE mechanisms provide new avenues to design 2D multiferroics, as we demonstrated in SrVO and CaFeO thin film cases. Our work not only reveals new physical mechanisms of 2D ferroelectricity in perovskite oxide thin films but also provides a new route to design the high-performance 2D FE and multiferroics.

Intrinsic Origin of Enhancement of Ferroelectricity in SnTe Ultrathin Films.

Previous studies showed that, as ferroelectric films become thinner, their Curie temperature (T_{c}) and polarization below T_{c} both typically decrease. In contrast, a recent experiment [Chang et al., Science 353, 274 (2016)SCIEAS0036-807510.1126/science.aad8609] observed that atomic-thick SnTe films have a higher T_{c} than their bulk counterpart, which was attributed to extrinsic effects. We find, using first-principles calculations, that the 0-K energy barrier for the polarization switching (which is a quantity directly related to T_{c}) is higher in most investigated defect-free SnTe ultrathin films than that in bulk SnTe, and that the 5-unit-cell (UC) SnTe thin film has the largest energy barrier as a result of an interplay between hybridization interactions and Pauli repulsions. Further simulations, employing a presently developed effective Hamiltonian, confirm that freestanding, defect-free SnTe thin films have a higher T_{c} than bulk SnTe, except for the 1-UC case. Our work, therefore, demonstrates the possibility to intrinsically enhance ferroelectricity of ultrathin films by reducing their thickness.

Coexistence of Ferromagnetism and Ferroelectricity in Cu-Intercalated Bilayer CrI3.

Design of two-dimensional (2D) multiferroic materials with two or more ferroic orders in one structure is highly desired in view of the development of next-generation electronic devices. Unfortunately, experimental or theoretical discovery of 2D intrinsic multiferroic materials is rare. Using first-principles calculation methods, we report the realization of multiferroics that couple ferromagnetism and ferroelectricity by intercalating Cu atoms in bilayer CrI3, Cux@bi-CrI3 (x = 0.03, 0.06, and 0.25). Our results show that the intercalation of Cu atoms leads to the inversion symmetry breaking of bilayer CrI3 and produces intercalation density-dependent out-of-plane electric polarization, around 18.84-90.31 pC·cm-2. Moreover, the switch barriers of Cux@bi-CrI3 in both polarization states are small, ranging from 0.31 to 0.69 eV. Furthermore, the magnetoelectric coupling properties of Cux@bi-CrI3 can be modulated via varying the metal ion intercalation density, and half-metal to semiconductor transition can be occurred by decreasing the intercalation density of metal ions. Our work paves a practical path for 2D magnetoelectron coupling devices.

Exploring consumers' environmental ethical preferences in the context of unmanned aerial vehicle utilization for plant protection.

The use of unmanned aerial vehicles (UAVs) has increased agricultural productivity, achieved food security, and eased the pressure associated with environmental degradation and population growth. However, consumer sentiment remains unclear. The results show that pressures regarding food safety, production safety, and ecological safety have different degrees of positive impact on perceived benefits but no significant impact on perceived barriers. They strongly influence both perceived benefits to the adoption of UAV plant protection agricultural products. Perceived benefits demonstrated a mediating role between the three safety pressures and the adoption of UAVs. Lay beliefs showed a positive moderating effect on perceived benefits and obstacles to the adoption of UAV-based plant protection products. Based on these findings, this paper concludes that consumers are developing new consumer ethics that integrate concepts of food safety, safe production, and regional environmental protection with their acceptance of new technology, which is directly dependent on the combined effect of environmental and consumer ethics. To promote sustainable development, policies must be further optimized on this original basis.

Chloroplast metalloproteinase SlL2 reduces the thermotolerance of tomato by decreasing the content of SlCDJ1.

Chloroplast is one of the most sensitive organelles to heat stress in plants. In chloroplasts, various proteases affect photosynthesis by degrading proteins under stress conditions. Tomato Lutescent2 (SlL2), a chloroplast zinc metalloprotease, was previously reported to alter chloroplast development and delay fruit ripening. However, its enzyme activity and roles in plant response to abiotic stress are still unclear. Here, we confirmed that the SlL2 protein which localized on thylakoid membrane was an ATP-independent hydrolase, and SlL2 gene responded to heat stress. Phenotype analysis showed that SlL2 plays a negative role in the heat-response mechanism. Under heat stress, the transgenic plants overexpressing SlL2 (OE) grew worse than the wild type (WT), as reflected by their decreased membrane stability, osmotic-regulating substance, and antioxidative enzyme activities, as well as increased reactive oxygen species (ROS) accumulation. By contrast, l2 mutant line showed the opposite phenotype and corresponding physiological indices under heat stress. In addition, overexpression of SlL2 decreased the photosynthetic activities, especially photosystem II. Moreover, SlL2 was found to interact with chloroplast-located chaperone protein SlCDJ1, decreasing its content under heat stress. These results indicate that SlL2 reduces the thermotolerance of tomato by reducing the content of SlCDJ1.

Quantitative Proteomics Analysis Reveals the Effect of a MarR Family Transcriptional Regulator AHA_2124 on Aeromonas hydrophila.

The transcriptional regulators of the MarR family play an important role in diverse bacterial physiologic functions, whereas their effect and intrinsic regulatory mechanism on the aquatic pathogenic bacterium Aeromonas hydrophila are, clearly, still unknown. In this study, we firstly constructed a deletion strain of AHA_2124 (ΔAHA_2124) of a MarR family transcriptional regulator in Aeromonas hydrophila ATCC 7966 (wild type), and found that the deletion of AHA_2124 caused significantly enhanced hemolytic activity, extracellular protease activity, and motility when compared with the wild type. The differentially abundant proteins (DAPs) were compared by using data-independent acquisition (DIA), based on a quantitative proteomics technology, between the ΔAHA_2124 strain and wild type, and there were 178 DAPs including 80 proteins up-regulated and 98 proteins down-regulated. The bioinformatics analysis showed that the deletion of gene AHA_2124 led to some changes in the abundance of proteins related to multiple biological processes, such as translation, peptide transport, and oxidation and reduction. These results provided a theoretical basis for better exploring the regulatory mechanism of the MarR family transcriptional regulators of Aeromonas hydrophila on bacterial physiological functions.

TMB12: a newly designed 2D transition-metal boride for spintronics and electrochemical catalyst applications.

Exploring two-dimensional (2D) ferromagnetic materials with a high transition temperature and large magnetic anisotropy is extremely essential for highly efficient spintronic applications. With the density functional theory method, we predicted planar hypercoordinate transition-metal borides, TMB12 (TM = Ti, V, Cr, Mn, Fe; B = boron), by the condensation of TM@B8 and B4 units. The results showed that these transition-metal borides possess superior thermal, dynamic and mechanical stabilities. Interestingly, the TMB12 monolayer with TM = (V, Cr) is confirmed as a robust ferromagnetic metal with a high Curie temperature of ∼335 K and ∼221 K, respectively. In addition, the system with TM = (Mn, Fe) is found to be an antiferromagnetic metal with a Néel temperature of ∼173 K and ∼91 K, respectively. In particular, large perpendicular magnetic anisotropy is identified for CrB12, MnB12, and FeB12 monolayers, around 198-623 µeV. Furthermore, four TMB12 (TM = Ti, V, Cr, Mn) systems are determined to be candidate catalysts for the hydrogen evolution reaction, with nearly zero free energy of hydrogen adsorption (ΔGH = -0.0003 to -0.03 eV). Our study highlighted potential 2D metal borides for spintronic devices and high efficiency electrochemical catalysts.

Insight into the quantum anomalous Hall states in two-dimensional kagome Cr3Se4 and Fe3S4 monolayers.

To realize the quantum anomalous Hall (QAH) effect in two-dimensional (2D) intrinsic magnetic materials, which combines insulating bulk states and metallic edge channel states, is still challenging in experiment. Here, based on first-principles calculations, we predicted two stable kagome-latticed QAH insulators: Cr3Se4 and Fe3S4 monolayers, with the Chern number C = 1. It is found that both structures exhibit a large magnetic anisotropy energy and sizable band gaps, and a topological phase transition from C = -1 to C = 1 occurs when the magnetization orientation changes from the z-axis to the -z-axis. Remarkably, the non-trivial topological properties are robust against biaxial strains of up to ±6%. Furthermore, a variable high Chern number of C = 2 or C = 3 can be observed by stacking two or three layers of the QAH monolayer with an MoS2 insulator. Our results signify that such layered kagome materials can be promising platforms for exploring novel QAH physics.

Comprehensive Screening of Halogen-Containing Oxide Double Perovskites A2BXO6 (X = Cl, Br, and I) for Photovoltaic Applications.

The new halogen-containing oxide double perovskites A2BXO6 (X = Cl, Br, and I) have attracted much attention because of their superb electronic properties in halide double perovskites and their high stability in oxide double perovskites. Herein, 408 A2BXO6 double perovskites have been systematically screened by high-throughput computation. Refer to the empirical structural factors phase diagram (t-u), which uses large-scale first-principles calculations. Fourteen stable perovskites are finally confirmed; moreover, 11 of them have never been reported before. Our results show that Ba2AgIO6 and Sr2AgIO6 are the most preferable candidates for photovoltaic applications, of which Sr2AgIO6 has balanceable electron and hole effective masses, a quasi-direct band gap, and strong optical absorption. Importantly, Sr2AgIO6 was successfully synthesized by the solution method. Our work enriches the family of double perovskites, and the tentative experimental evidence undoubtedly hints at their great potential applications in the near future.

Efficient Gradient Potential Top Electron Transport Structures Achieved by Combining an Oxide Family for Inverted Perovskite Solar Cells with High Efficiency and Stability.

Although inverted (p-i-n) structure perovskite solar cells (PSCs) have achieved high efficiency by commonly using fullerenes or their derivatives as electron transport layers (ETLs), the device stability and cost of fullerene materials are still of great concern. Herein, we demonstrate inorganic top ETLs simply composed from a family of metal oxides including In2O3 and its derivative of Sn:In2O3 with a gradient potential structure. For inverted PSCs, the typical film formation process of In2O3 will damage or degrade perovskite materials underneath; thus, we report a low temperature synthesis approach for obtaining In2O3 and Sn:In2O3 nanoparticles that can form effective top ETLs without any post-treatment. The one-family oxide-based top ETL features with the enhanced built-in potential, high electron extraction, and low interfacial recombination, offering a power conversion efficiency (PCE) of 20.65% in PSCs constructed from oxide-only carrier (both hole and electron) transport layers (CTLs), which is the highest efficiency in oxide-only CTL-based inverted PSCs to the best of our knowledge. Equally important, the inverted PSCs based on the Sn:In2O3/In2O3 ETL show the excellent operational stability and remain 90% of the initial value of PCE over 2000 h. Consequently, this work contributes to the robust strategy of all oxide-only CTLs in developing rigid and flexible PSCs for practical photovoltaic applications.

Particulate plastics-plant interaction in soil and its implications: A review.

Particulate plastics (<5 mm), including macroplastics (1 µm to 5 mm), microplastics (100 nm to 1 µm) and nanoplastics (<100 nm), have become a global environmental problem due to their widespread occurrence, distribution and ecosystem risk. Although numerous studies on particulate plastics have been conducted in aquatic systems, investigations in the soil ecosystem are lacking. Soil is the main storage place of particulate plastics, conferring significant impacts on plant growth and development. The impact of particulate plastics on plants is directly related to the safety of agricultural products. This review comprehensively examines the pollution characteristics and exposure pathways of particulate plastics in agricultural soils, highlighting plastic uptake process, and mechanisms in plants, and effects of particulate plastics, biodegradable particulate plastics and combined pollution of plastics with other environmental pollutants on plant performances. This review identifies a number of future research prospects including the development of accurate quantitative methods for plastic analysis in soil and plant samples, understanding the environmental behaviors of conventional and biodegradable particulate plastics in the presence and absence of other environmental pollutants, unravelling the fate of particulate plastics in plants, phyto-toxicity and molecular regulatory mechanisms of particultate plastics, and developing best management practices for the production of safe agricultural products in plastic-contaminated soils.

Iohexol Clearance for Determination of Glomerular Filtration Rate in Cynomolgus Monkeys (Macaca fascicularis).

The purpose of this study was to validate a method for determine the glomerular filtration rate (GFR) in healthy cynomolgus monkeys by using iohexol. Eighteen healthy cynomolgus macaque monkeys (age, 4 to 6 y [mean, 5 y]; weight, 2 to 6 kg [mean, 4 kg]) were randomly entered into 3 different doses groups (3 male and 3 female macaques per group) of 30, 60, 90 mg I/kg to receive an intravenous bolus injection of iohexol. Serum iohexol concentrations were determined by using liquid chromatography-tandem mass spectrometry, and clearance rate were determined by using WinNonlin software. The GFR value (mean ± SD) of each dose group was 2.50 ± 0.321, 2.65 ± 0.529, and 2.75 ± 0.385 mL/min/kg. These values did not differ significantly between dose levels or sexes. Iohexol clearance is a simple, precise method that is suitable for the determination of GFR in cynomolgus monkeys.

[Impact in response control, attention and hyperactivity behavior on children with obstructive sleep apnea hypopnea syndrome by integrated visual and auditory continuous performance test].

OBJECTIVE: To study the impact in response control, attention and hyperactivity behavior on children with obstructive sleep apnea hypopnea syndrome (OSAHS) by the integrated visual and auditory continuous performance test (IVA-CPT). METHODS: Fifty-one children aged between 5 and 12 years were diagnosed as OSAHS by polysomnography (PSG), and received adenotonsillectomy and adenoidectomy or only adenoidectomy. Then received IVA-CPT and PSG before surgery, 3 months after surgery and 6 months after surgery (named as first, second and third time point). These children were divided into two groups according to the disease course (group A: course of disease < 5 years; group B: course of disease ≥ 5 years). The SPSS 19.0 was used for statistical analysis. RESULTS: By balanced test, there were no differences in gender, body mass index (BMI) and disease severity among the two groups before surgery (P > 0.05). The numbers of children with abnormal psychological behavior at three time points were 32 (62.7%), 25 (49.0%) and 8 (15.7%). The abnormal rate did not show statistical difference between the first and second time point (χ(2) = 1.49, P = 0.163), but did show statistical difference between the second and third time point (χ(2) = 12.95, P < 0.001). Repetitive measurement and analysis of variance showed that there were statistical differences in means of FRCQ, FAQ and HYP between three time points in two groups (F were 342.15, 263.12, 380.57, P < 0.001), and all the means improved with time. It also showed that there were statistical differences in means of FRCQ, FAQ and HYP between two groups at every time point (F were 167.05, 126.47, 117.683, P < 0.001). FRCQ and HYP all showed interation effect between two groups (P < 0.001). Means of apnea hypopnea index (AHI) and lowest arterial (LaSO2) were compared between three time points in two groups and all showed statistical differences (F were 99.057, 70.742, P < 0.001). Means of AHI and LaSO2 were compared between two groups at every time point. AHI and LaSO2 did not show statistical difference (P > 0.05). AHI and LaSO2 did not exist interation effect of disease course and time. CONCLUSIONS: OSAHS obviously affect the children's response control, attention and hyperactivity behavior, but can recover gradually after adenotonsillectomy and adenoidectomy or only adenoidectomy. Therefore, Children with OSAHS should receive treatment as early as possible so as to reduce the influence on psychology.