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Farm ponds, which are sometimes numerous and widely distributed in agricultural regions, have faced widespread degradation in recent decades. Although conservation strategies for these biodiversity hotspots have gradually increased, appropriate approaches for developing country contexts are lacking. Farm ponds provided hydrologic, biogeochemical, and socioeconomic benefits to southern China for thousands of years, but they are facing contemporary threats and management challenges, including (1) inadequate planning in terms of construction and conservation regulations; (2) rural nonpoint source and mini-point source pollution; (3) climate change induced abnormalities in the hydroperiod and disturbance to wildlife; (4) invasive species; and (5) inadequate social and political capacity to consider ecological conservation. Because farm ponds function as wetland complexes that are embedded within or integral to larger ecosystems, their conservation requires collaborative efforts over scales ranging from within-pond to regional. We highlight approaches that build public awareness and involve inventory maps as a basis. Policies that integrate top-down regulation and bottom-up engagement and emphasize sustainable management and utilization are recommended to ensure the effectiveness and continuous improvement of conservation programs. Techniques that involve interconnected smart sensors, volunteering and citizen science, and integrated process-based modeling are preferred when conducting comprehensive descriptions of the pond landscape, numerical assessments on their ecosystem services, and associated conservation cost analyses. Nature-based solutions are increasingly recognized as an important opportunity for coping with water-related crises. This paper presents the first synthetic perspective on the ecological roles of farm ponds in agriculturally dominated developing countries. The analytical framework and conservation suggestions are referential to sustainable rural development and the management of other small, scattered wetlands.

Nanolayered metallic composites usually deform via a transition from homogeneous deformation to major shear banding with decreasing layer thickness, and thus the improvement of strength often sacrifices the plasticity of materials. Here, we show two methods to promote brittle-to-ductile transition in nanolayered Ag/Nb pillars. Intrinsically, while keeping the pillar diameter constant, the reduction of layer thickness can increase the strength of multilayers and suppress shear induced failure. Extrinsically, for a constant layer thickness, decreasing the diameter of pillar suppresses shear bands and promotes more uniform plastic deformation. Furthermore, the critical layer thickness at peak strength of multilayers increases monotonically with decreasing pillar diameter. Interface structures evolve from amorphous layer to coherent interface with reduction of layer thickness. Homogeneous co-deformation mediated by heterogeneous interfaces and columnar grain boundaries promotes a unique work hardening behavior. This study indicates that a combination of intrinsic and extrinsic size effect may enable the accomplishment of high strength and uniform deformation simultaneously.

Vasoactive intestinal peptide receptor 1 (VIPR1) is observed to express differently in human malignancies. Here, we aim to reveal clinical significance and transcriptional regulation mechanism of VIPR1 in hepatocellular carcinoma (HCC). Using immunohistochemistry, pyrosequencing, quantitative real-time PCR (qPCR), decitabine (DAC)/4-phenylbutyricacid (PBA) treatment and chromatin immunoprecipitation (ChIP), we found the low expression of VIPR1 was correlated with poor histological differentiation and poor survival. The promoter region of VIPR1 was methylated and DNA methylation inhibited VIPR1 gene transcription. Deacetylation of H3K27 in the promoter of VIPR1 inhibited the transcription of VIPR1 in HCC. In conclusion, low expression of VIPR1 had an adverse prognostic impact on HCC, and such expression is at least partially mediated by epigenetic modification.

Gallium nitride (GaN) nanowires and nanotubes possess extraordinary device ability of converting wasted energy into harvestable electricity in terms of their piezoelectricity and pyroelectricity. From the perspective of atomic cohesive energy, we present a model to clarify the physical origin of the size- and shape-dependency of the piezoelectric and pyroelectric properties for intrinsic GaN nanowires and nanotubes. It is shown that both the piezopotential and the pyropotential increase with the inverse of GaN nanocrystal size or with the shape factor. The influence of size and shape becomes more significant for nanotubes with smaller size or wall thick-to-size ratio and may enhance both potentials by up to dozens of times or even more. Such size and shape effects originate from the synergetic effects of nanoscale dielectricity, piezoelectricity and thermoelasticity where the piezoelectricity plays a more important role than the other two factors. Moreover, high piezopotential and pyropotential in GaN nanotubes render them appealing in the design of novel nanogenerators in comparison with the most commonly used nanowires.

In this work, two-dimensional few-layer palladium ditelluride (PdTe2) nanosheets are produced by the simple and effective ultrasonic liquid exfoliation method and used as novel saturable absorber in an Yb-doped mode-locked fiber laser. The results show that the prepared flexible PdTe2/PVA composite film has a modulation of 3.7% and a saturation intensity of 77.6 MW/cm2. The obtained Yb-doped mode-locked fiber laser based on the film shows a pulse width of 887.2 ps with a repetition and central wavelength of 8.921 MHz and 1069 nm, respectively. So far, there has been few reports on PdTe2 as saturable absorbers to realize mode-locked fiber lasers. The results suggest that two-dimensional PdTe2 has great potential applications in nonlinear optics and ultrafast photonics.

In this work, we have systematically investigated the effect of cyclic deformation on the strength and rate sensitivity of Cu/Ru multilayers with different individual layer thickness ( h ) by nanoindentation tests. It was found that cyclic deformation remarkably enhances the hardness of Cu/Ru multilayers comparing with the specimens by monotonic loading. The rate sensitivity ( m ) of multilayer exhibits an anomalous size dependence after nanoscale cyclic deformation. When h > 10 nm, the m linearly increases with increasing cycle number of loading-unloading ( s ). However, the m sharply decreases with increasing s when h m . An obvious Bauschinger effect is observed during cyclic loading, where the evolution of effective stress is consistent with the m . Cyclic deformation induced dislocation accumulation and arrays at the heterogeneous interface are the intrinsic plastic mechanism for the enhanced rate sensitivity. The formation of amorphous layers at the critical h is mainly responsible for the inverse size m .

Osteoarthritis (OA) has traditionally been defined as a non-inflammatory disease. Recently, many studies have demonstrated that OA also has an inflammatory component. BRD4, a member of the Bromodomain and Extra-Terminal Domain family, has emerged as an important regulator of some chronic inflammatory diseases. JQ1, an antagonist of BRD4, modulates transcription of several genes. Our study demonstrated that BRD4 is up-regulated in articular cartilage of OA. BRD4 inhibition attenuated the inflammation and catabolism of chondrocytes and suppressed NF-κB signalling pathway activation. In addition, BRD4 inhibition abolished the transcriptional activity of High Mobility Group Protein B1 (HMGB1). We identified HMGB1 as a direct target of BRD4. Genetic and pharmacological inhibition of BRD4 suppressed IL-1β-induced expression and translocation of HMGB1. Chromatin immunoprecipitation (ChIP) showed the enrichment of BRD4 around the HMGB1 upstream non-promoter region, which diminished with JQ1 treatment. Finally, haematoxylin & eosin and Safranin o/Fast Green staining demonstrated that JQ1 attenuates cartilage destruction in mice with anterior cruciate ligament transection without significant toxic effects. These studies highlighted the importance of BRD4 in the chronic inflammatory reactions of OA, which, as far as we know, was the first report of this finding, and suggested that BRD4 might be a novel potential therapeutic target for the treatment of OA.

We explore a first-principles study of the structural, electronic, magnetic, and optoelectronic properties of two-dimensional (2D) gallium nitride (GaN) adsorbed by the groups IIIA-VIIA atoms. Our calculations reveal that the chemisorption occurs for all selected adatoms and the adsorption energy of C is the highest because of its special adsorption configuration. The electronic structure studies indicate that the adatoms introduce magnetic feature with spin-polarized properties except for the group VIA atoms. Moreover, a semiconducting state presents in the groups IIIA, IVA and VIA atoms adsorbed 2D GaN, while a half-metallic state appears in 2D GaN after the adsorption of VA and VIIA atoms, which makes the latter higher work functions. Such regular modifications in physical properties of 2D GaN induced by adsorption could potentially allow use of this material in diverse electronic, optoelectronic, and spintronic applications.

In this work, the indentation-induced incipient plasticity of Ni 3 Al crystal is investigated by performing molecular dynamics (MD) simulations. Simulation results reveal that the incipient plasticity of Ni 3 Al is originated from the homogeneous nucleation of the 1/6〈1 1 2〉-type Shockley partial dislocation. The critical load, critical contact pressure, dislocation nucleation site and active slip system are significantly affected by crystallographic orientation, model size, indenter radius and temperature. The choice of interatomic potential has significant implications for the indentation behavior of Ni 3 Al. Some benchmarks for evaluating the credibility of interatomic potentials are presented. The pop-in phenomena are correlated with dislocation generation, multiplication and reactions. The formation mechanisms of complex stacking faults (CSFs), antiphase boundaries (APBs) and superlattice intrinsic stacking faults (SISFs) are clarified. The highest indentation modulus is obtained in (1 1 1) indentation followed by the (1 1 0) and (1 0 0) cases. The indentation modulus and the depth of nucleation sites increase with increasing indenter radius but the maximum shear stress decreases. The maximum shear stress and indentation modulus decrease linearly with increasing temperature, reflecting the stress-assisted and thermally activated nature of dislocation nucleation.

Study region: The WE-38 Experimental Watershed, which is a small (7.3 km2) basin in the Ridge and Valley physiographic region of east-central Pennsylvania. Study focus: We used non-parametric Mann-Kendall tests to examine long-term (1968 to 2012) hydroclimatic (precipitation, temperature, streamflow) trends in WE-38 in the context of recent climate change across northeastern US. New hydrological insights for the region: Annual mean temperatures in WE-38 increased 0.38 °C per decade, leading to an expansion of the growing season (+2.8 days per decade) and a contraction of frost days (-3.6 days per decade). Consistent with increased temperatures, annual actual evapotranspiration rose significantly (+37.1 mm per decade) over the study period. Precipitation also trended upward, with October experiencing the most significant increases in monthly total rainfall (+8.2 mm per decade). While augmented October precipitation led to increased October streamflow (+5.0 mm per decade), the trend in WE-38 streamflow was downward, with the most significant declines in July (-1.2 mm per decade) and February (-7.5 mm per decade). Declines in summertime streamflow also increased the duration of hydrological droughts (maximum consecutive days with streamflow < 10th percentile) by 1.9 days per decade. While our findings suggest some challenges for producers and water resource managers, most notably with increased fall rainfall and runoff, some changes such as enhanced growing seasons can be viewed positively, at least in the near term.

Bone homeostasis requires a dynamic balance between osteogenesis and osteoclastogenesis, and osteolytic disorders are mainly attributed to aberrant osteoclastogenesis and bone resorption. Accumulating evidence has demonstrated that cyclin-dependent kinase 9 (CDK9) regulates some inflammatory diseases without affecting the cell cycle. Whether the specific inhibitor of CDK9, LDC000067 (abbreviated as LDC067), helps to prevent from osteolytic disorders has not been fully elucidated. Interestingly, this study demonstrated that LDC067 inhibited receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis and bone resorption in vitro, and suppressed the expression of osteoclast-related marker genes such as cathepsin K (CTSK), tartrate-resistant acid phosphatase (TRAP), dendrite cell-specific transmembrane protein (DC-STAMP), V-ATPase D2, calcitonin receptor (CTR) and nuclear factor of activated T cells cytoplasmic 1 (NFATc1). The bone protective effects of LDC067 can be partly explained by its suppression of nuclear factor-kappa B (NF-κB)-mediated NFATc1 activation via AKT signalling pathway. In keeping with the results obtained in vitro, inhibition of CDK9 with LDC067 was observed to delay subchondral osteolysis and substantially ameliorate LPS-induced osteolysis in murine calvaria. Collectively, these results highlight the positive effects of LDC067 in preventing osteolytic disorders and indicate that this CDK9 inhibitor may a promising therapeutic agent.

The thickness dependent crystallization behavior of thin amorphous Ge 2 Sb 2 Te 5 (GST) films sandwiched between different cladding materials has been investigated based on a thermodynamic model. It is revealed that there is a critical thickness below which the crystallization cannot occur. The critical thickness is determined by the energy difference Δ γ between the crystalline GST/substrate interface energy and the amorphous GST/substrate interface energy, the melting enthalpy, and the mole volume. The calculated result is in good agreement with the experiments. Furthermore, the crystallization temperature is also affected by interface energy difference Δ γ . Larger Δ γ gives rise to a higher crystallization temperature, and vice versa. This impact becomes stronger as the film thickness is decreased.

The effects of barrier layers and annealing temperature on texture variation, grain growth and void forming of nanocrystalline Cu films were investigated by X-ray diffraction, transmission electron microscope and scanning electron microscope (SEM). The variation in texture and grain size of Cu films with annealing temperature is different for Cu/Ti and Cu/Ta. The activation energies of grain growth of Cu films on Ti and Ta, respectively, are 19.7 and 23.4 kJ mol −1 , which are much closer to that of grain boundary diffusion of Cu. The average diameter of about 400 nm for surface voids of Cu/Ti is larger than that of Cu/Ta structure. Furthermore, both the electrical resistivity measurement and SEM observation imply that Cu/Ti rather than Cu/Ta structure tend to fail easier as annealing temperature exceed 400 °C.

Nanoindentation creep tests were carried out at maximum indentation loads from 500 to 9000 μN to study the indentation size effects (ISEs) on the creep behavior of nanocrystalline tetragonal Ta films. The experimental results show that the hardness, creep strain rate and stress exponent are all indentation size-dependent. The ISE on the creep behavior is explained by grain boundary diffusion and sliding, and self-diffusion along the indenter/specimen interface and along the free surface of specimen.

Reducing the sizes of low dimensional materials leads to dramatic increase in the portion of surface/interface atoms. The properties of a solid are essentially controlled by related surface/interface energies. Although such changes are believed to dominate behaviors of nanoscale structures, little experience or intuition for the expected phenomena, especially for the size-dependence of the energies and their practical implications, are modeled analytically. In this contribution, the classic thermodynamics as a powerful traditional theoretical tool is used to model different bulk interface energies and the corresponding size dependences. During the modeling, an emphasis on size dependences of the interface energies is given, which is induced by size dependence of coherent energy of atoms within nanocrystals. It is found that solid–vapor interface energy, liquid–vapor interface energy, solid–liquid interface energy, and solid–solid interface energy of nanoparticles and thin films fall as their diameters or thickness decrease to several nanometers while the solid–vapor interface energy ratio between different facets is size-independent and equals to the corresponding bulk value. The predictions of the established analytic models without any free parameters, such as size and temperature, dependences of these four kinds of interface energies and related surface stress, correspond to experimental or other theoretical results. The above established models are suitable for low-dimensional materials with different dimensions and different chemical bond natures. Moreover, several related applications in the fields of nanophase transitions, nanocrystal growth, and self-diffusion of liquids are provided.

In this paper, the shape evolution and thermal stability of Ag nanoparticles (NPs) on spherical SiO{sub 2} substrates were investigated by means of in situ transmission electron microscopy (TEM) imaging and differential scanning calorimetry (DSC). The initial Ag NPs at room temperature were semispherical-like, with an average size of 9 nm in half-height width, well-dispersed on spherical SiO{sub 2} substrates. No obvious shape change was observed when the semispherical NPs of Ag were heated at temperature lower than 550 deg. C. The shape of the semispherical Ag NPs changed gradually into a spherical one in the temperature range of 550-700 deg. C, where surface diffusion and surface premelting took place. When the heating temperature was increased up to 750 deg. C, the spherical Ag NPs were found to desquamate from the substrates due to the decreases of the contact area and the binding force between Ag NPs and SiO{sub 2} substrates. A possible mechanism for the desquamation of Ag NPs from the SiO{sub 2} sphere surface is proposed according to the results of in situ TEM observation and DSC analysis. - Graphical abstract: The shape evolution and thermal stability of Ag nanoparticles (NPs) on spherical SiO{sub 2} substrates were investigatedmore » by means of in situ TEM imaging and DSC analysis. A possible mechanism for the desquamation of Ag NPs from the SiO{sub 2} sphere surface is proposed. Here, a simple sketch is shown to describe the shape evolution and desquamation process of the Ag NPs.« less

Silica-silver core-shell composite particles with uniform thin silver layers were successfully synthesized by a facile and one-step ultrasonic electrodeposition method. By electrolysis of the slurry consisting of preformed silica spheres and silver perchlorate without any additives, the homogenous composite particles can be prepared. The average size of single silver crystals in the composite is about 12 nm and the thickness of silver layer is 14{+-}2 nm. Moreover, the continuity of Ag distribution, the surface roughness and the thickness of silver layer are controllable by adjusting the current density (I), the concentration of electrolyte (C) and the reaction time (t). Optical properties of the composite particles with different silver content were also investigated. - Graphical abstract: Silica-silver core-shell composite particles with uniform thin silver layers are prepared by a facile and one-step ultrasonic electrodeposition method. Moreover, the continuity of Ag distribution, the surface roughness and the thickness of silver layer are controllable. Optical properties of the composite particles with different silver content were also investigated.

Temperature-dependent surface tension γlv(T) and its temperature coefficient γ′lv(T)=dγlv(T)/dT for liquid silicon and germanium (l-Si and l-Ge) are thermodynamically modeled based on an established model for surface energy of crystals. Combining the relationship among γlv(T), self-diffusion coefficient D and liquid viscosity η, temperature dependent D(T) function is also modeled. The model predictions correspond to the available experimental results. It is found that γlv(T)∝T, γ′lv(T)∝T and D(T)∝T3/2 at a certain temperature range (including T T m and T ⩾ T m where Tm is the melting temperature).

The temperature-dependent self-diffusion coefficient D ( T ) in liquid metals between the melting temperature T m and boiling point T b is modeled in terms of the relationship among D , liquid viscosity η , and liquid–vapor surface tension γ lv . The model predictions for D ( T ) correspond to available experimental and molecular dynamics (MD) simulations results for liquid alkali metals Li, Na, Rb and Cs, semi-metal Al, transition and noble metals Ni, Cu, Ag and Au.

Based on the previous models for bulk and size-dependent solid–liquid interfacial energy γ sl0 and γ sl ( r ) with the additional temperature-dependent melting enthalpy Δ H m ( T ) and improved Gibbs free energy difference functions g m ( T ) between crystal and liquid, γ sl ( r , T ) function is quantitatively modeled. It is found that the γ CNT values of Turnbull's undercooling experiments correspond to the model predictions for the nucleus–liquid interfacial energy rather than γ sl0 . This correspondence leads to the reexaminations on the classic nucleation theory. Moreover, the linear relationship between γ sl ( r , T ) and Δ H m / V is found to be always valid at any degree of undercooling where V is the molar volume. Finally, the size range of γ sl ( r , T ) for elements is also discussed.

A quantitative thermodynamic correlation method to describe the size dependent Langmuir adsorption isotherm is developed. According to the model, the equilibrium adsorption constant increases as material size decreases, which is in agreement with the literature data of acetic acid, valeric acid, oxalic acid, and adipic acid on anatase nanoparticles.

Interface stress and interface free energy models are introduced into phase equilibrium conditions of a binary phase diagram. The existence of the interface stress leads to shifts of the Gibbs free energy curve of a second compressible phase upwards and rightwards in comparison with that of the corresponding incompressible phase.

Gas-liquid two-phase flows are widely used in the chemical industry. Accurate measurements of flow parameters, such as flow regimes, are the key of operating efficiency. Due to the interface complexity of a two-phase flow, it is very difficult to monitor and distinguish flow regimes on-line and real time. In this paper we propose a cost-effective and computation-efficient acoustic emission (AE) detection system combined with artificial neural network technology to recognize four major patterns in an air-water vertical two-phase flow column. Several crucial AE parameters are explored and validated, and we found that the density of acoustic emission events and ring-down counts are two excellent indicators for the flow pattern recognition problems. Instead of the traditional Fair map, a hit-count map is developed and a multilayer Perceptron neural network is designed as a decision maker to describe an approximate transmission stage of a given two-phase flow system.