Heterogeneous Growth Research Articles

In Situ High-Pressure Correlated Transportation of Heavy Rare-Earth Perovskite Nickelates as Batch Synthesized within Eutectic Molten Salts at MPa-pO2.

The multiple magneto-/electrical quantum transitions discovered with d-band correlated metastable perovskite oxides, such as rare-earth nickelate (ReNiO3), enable applications in artificial intelligence and multifunctional sensors. Nevertheless, to date such investigation merely focuses on ReNiO3 with light or middle rare-earth composition, while the analogous explorations toward heavy rare-earth (ReHNiO3, ReH after Gd) are impeded by their ineffective material synthesis relying on GPa pressure. Herein, for the first time we synthesized the powder of ReHNiO3 in grams/batch with ∼1000 times lower pressure and ∼300 °C lower temperature in comparison to the previous ∼101 milligram/batch results, assisted by their eutectic precipitation and heterogeneous growth within alkali-metal halide molten salt at MPa oxygen pressures. Further in situ characterizations under high pressures within a diamond anvil cell reveal a distinguishing pressure predominated bad metal transport within the nonequilibrium state of ReHNiO3 showing high-pressure sensitivity up to 10 GPa, and the temperature dependences in electrical transportations are effectively frozen.

Flexible and highly-loaded mixed-matrix membrane with bi-continuous metal–organic frameworks transfer pathway for gas separation

Highly-loaded metal–organic frameworks (MOFs) based mixed matrix membranes (MMMs) are essential for high-efficiency gas separation. However, the continuous distribution of MOFs across the membrane with intensified interface remains challenging. Herein, a flexible and defects-free MMM with a bi-continuous MOFs pathway is constructed by dopamine (DA)-assisted MOFs growth along nanofibers. Nanofibers are used to upload and distribute ZIF-8, which continues to grow via an epitaxial growth strategy to obtain ZIF-8 fibers, achieving ZIF-8 continuous both in long and short range. DA promotes heterogeneous nucleation and growth of ZIF-8 on fiber surface by chelating with Zn2+ through –OH and –NH2 groups. DA also ensures excellent interfacial compatibility by hydrogen bonding interaction between amino groups of DA and ether-oxygen groups of PEO. Finally, the highly-loaded MMM is constructed by in-situ photopolymerization of Poly (ethylene glycol) diacrylate) to embrace ZIF-8 fibers tightly. The resultant MMM presents ZIF-8 loading as high as 72.41 vol% with Young’s modulus of 33.42 MPa, and unchanged morphology and separation performances after bending for 180° over 50 times, revealing outstanding mechanical properties. The CO2 permeability and CO2/N2 selectivity are 280.3 % and 73.0 % higher than the PEO membrane, surpassing the 2019 McKeown upper bound.

Influence of solute content and cooling rate on the preparation of semi-solid slurries for novel creep-resistant Mg-Gd-Ca-Zr alloys

The semi-solid Mg-Gd-Ca-Zr alloys slurries with fine and spherical α-Mg particles were successfully prepared. The influence of solute Gd and Zr contents, and cooling rate on the morphological evolution of α-Mg are systematically investigated. The results showed that addition of Zr will turn the coarse dendritic α-Mg particles into fine and globular particles. With the increase of Zr addition from 0 to 0.6 wt%, the particle size decreases, and the particle density and shape factor increase continuously. With the change of solute Gd content from 5 to 15 wt% in the Mg-yGd-2Ca-0.6Zr alloy, the particle size of α-Mg particles decreases continuously, and shape factor increases continuously. With cooling rate decreases from 3 to 1.5 °C/min, the α-Mg particles are slightly coarsened and the morphology are kept nearly globular, while with further decreasing into 0.5 °C/min, the α-Mg particles are severely coarsened and turned into irregular shape. The optimal Zr addition is ∼0.6 wt% and Gd addition is no less than 10 wt%, and the optimal cooling rate is 1.5–3 °C/min. The mechanisms for obtaining fine and spherical α-Mg particles through Zr and Gd additions are discussed to be different roles of heterogenous nucleation effects and growth restriction effects.

Morphology Control of Au-Ni Hybrid Nanoparticles: Exploring Heterostructures and Optical Tuning.

Hybrid nanoparticles (NPs) have attracted considerable attention because of their ability to provide diverse properties by integrating the inherent properties of multiple components; however, synthetic strategies to control their morphology remain unexplored. In this study, a new method was used to control the morphology and optical properties of Au-Ni heterostructure (ANH) NPs. Unique morphological changes were observed by varying the Au/Ni precursor ratio from 2:1 to 1:4, exhibiting a shape transformation from dumbbell-like to quasi-spherical owing to the Ni NP size expansion, whereas the Au NP maintained their size. Moreover, increasing the Ni ratio induced plasmonic band broadening and wavelength redshift, resulting in color changes from red to navy and black. In terms of the structure, the atomic orientation of the crystallite showed that even a large lattice mismatch can result in heterojunctions at the NPs. In addition, the reaction aliquots uncovered heterogeneous nucleation and growth of ANH NPs in the colloidal system, demonstrating Ni reduction on the preformed Au NP owing to the reduction in potential gap. This study provides new insights into controlling the morphology of hybrid NPs using colloidal synthesis and the design of optimized materials for various applications.

Heterogeneous nucleation and growth of sessile chemically active droplets

Droplets are essential for spatially controlling biomolecules in cells. To work properly, cells need to control the emergence and morphology of droplets. On the one hand, driven chemical reactions can affect droplets profoundly. For instance, reactions can control how droplets nucleate and how large they grow. On the other hand, droplets coexist with various organelles and other structures inside cells, which could affect their nucleation and morphology. To understand the interplay of these two aspects, we study a continuous field theory of active phase separation. Our numerical simulations reveal that reactions suppress nucleation while attractive walls enhance it. Intriguingly, these two effects are coupled, leading to shapes that deviate substantially from the spherical caps predicted for passive systems. These distortions result from anisotropic fluxes responding to the boundary conditions dictated by the Young–Dupré equation. Interestingly, an electrostatic analogy of chemical reactions confirms these effects. We thus demonstrate how driven chemical reactions affect the emergence and morphology of droplets, which could be crucial for understanding biological cells and improving technical applications, e.g., in chemical engineering.

Praseodymium dysprosium co-doped M-type strontium ferrite: Intentionally manufacturing heterophase growth to improve microwave absorption performance

When excessive praseodymium and dysprosium ions are doped with M-type strontium ferrite, heterophases with different magnetic and electrical properties will be formed. We use this to intentionally induce different heterogeneous growth in the Pr–Dy co-doped strontium ferrite system. While maintaining the dielectric loss of the main phase, the produced heterogeneous phase acts as a companion for dielectric and magnetic losses. The synthesized SrFe12-2xPrxDyxO19 ferrite demonstrates its potential as a microwave absorbing material, exhibiting excellent absorption effects over a wide range of Pr–Dy doping (x = 0.05–1.5). The XRD results show that the synthesized materials include both pure M-phase and coexistence of M-phase and heterophases, and the generated heterophases are mainly perovskite type ferrite and garnet type ferrite. SEM and EDS results indicate that Pr–Dy co-doping can significantly refine the grain size, reduce the grain size of the main and heterophases, and lead to a decrease in oxygen content. The XPS analysis shows that some praseodymium ions are in the Pr4+ oxidation state, leading to the existence of Fe2+ ions and oxygen defects (Od). The VSM results indicate that at different calcination temperatures, the saturation magnetization decreases and the coercivity shows an increasing trend as the Pr–Dy doping amount increases. Pr–Dy doping not only increases the dielectric and magnetic losses of the M phase, but also generates heterophases that can enhance the dielectric and magnetic losses of the material, jointly improving the absorption effect. This results in excellent absorption performance of the material within a large range of praseodymium dysprosium doping contents (x = 0.05–1.5, RLmin = −52.51 dB, EABmax = 4.81 GHz).

Regional integration, agricultural production, and their heterogeneous interaction in the classic urban agglomeration of China

Regional integration, a global trend covering multiple aspects of cities that constitute an urban agglomeration, is poised to reallocate limited resources and reshape regional production pattern. While its effects on urban economic efficiency and environmental emissions have been investigated, the agricultural system, which plays a pivotal role in ensuring food security, remains an underexplored domain. To address this, this study commences by discussing the possible influence of regional integration on agricultural production drawing from literature and practical evidence. Then the regional integration level of the Yangtze River Delta Urban Agglomeration (YRDUA) from 2005 to 2019 was evaluated, which is a facet that has received limited quantitative scrutiny hitherto. Subsequently, the agricultural production efficiency (APE) that integrates the composite inputs and outputs information was analyzed to assess the utility of rural production. The interconnection between these two systems was then explored by panel Tobit Model. The findings reveal that (1) regional integration in the YRDUA has exhibited fluctuation across different developmental stages and is presently converging toward a state of stability. (2) The APE appears better performance characterized by weakened spatial heterogeneity and long-term growth. (3) The APE presents an increase in response to the improved integration levels within the gradients, and the model results suggest a positive relationship between them. The discovery of this study implied the potential of macro-regulation promoted through regional integration to enhance APE, underscoring its dual welfares, impacting not only urban development but also extending its spilled-beneficial effects to rural overall production. It provides insights to help find solutions to food security and regional equilibrium under the worldwide tendency of regional integration.

Heterogeneous identity, stiffness and growth characterise the shoot apex of Arabidopsis stem cell mutants.

Stem cell homeostasis in the shoot apical meristem involves a core regulatory feedback loop between the signalling peptide CLAVATA3, produced in stem cells, and the transcription factor WUSCHEL, expressed in the underlying organising centre. clavata mutant meristems display massive overgrowth, which is thought to be caused by stem cell overproliferation, although it is unknown how uncontrolled stem cell divisions lead to this altered morphology. Here we reveal local buckling defects in mutant meristems, and use analytical models to show how mechanical properties and growth rates may contribute to the phenotype. Indeed, clavata meristems are mechanically more heterogeneous than the wild type, and also display regional growth heterogeneities. Furthermore, stereotypical wild-type meristem organisation is lost in mutants, in which cells simultaneously express distinct fate markers. Finally, cells in mutant meristems are auxin responsive, suggesting that they are functionally distinguishable from wild-type stem cells. Thus all benchmarks show that clavata meristem cells are different from wild-type stem cells, suggesting that overgrowth is caused by the disruption of a more complex regulatory framework that maintains distinct genetic and functional domains in the meristem.

Evaluation of Automated Disk Diffusion Antimicrobial Susceptibility Testing Using Radian® In-Line Carousel

Antimicrobial susceptibility testing (AST) by disk diffusion provides an accurate image of bacterial growth, enabling the detection of culture purity, heterogeneous growth, and antibiotic interactions. However, this manual method is time-consuming and visual interpretation is prone to errors. To overcome these disadvantages, the Radian® In-Line Carousel (Copan, Brescia, Italy) was launched, which is a WASPLab® module dedicated to full automation of (pre)-analytical steps as well as interpretation of disk diffusion AST. However, until now, no evaluation of Radian® against manual disk diffusion has been performed. We assessed the categorical agreement (CA) between standardized disk diffusion (reference method) and Radian® using EUCAST 2021 breakpoints. We tested 135 non-duplicate strains, selected from the National EUCAST challenge panel, clinical strains, and external quality controls. The strains included Enterobacterales (n = 63), Enterococcus faecalis (n = 3), Enterococcus faecium (n = 10), Pseudomonas aeruginosa (n = 16), Staphylococcus aureus (n = 19), coagulase-negative staphylococci (n = 4), and Streptococcus spp. (n = 20). Furthermore, we explored antibiotic disk thermolability in the WASP Radian® carousel by testing 10 ATCC® strains up to 7 days. The observed CA was 95.3%, 96.3%, 93.8%, 97.3% and 98.0% for Enterobacterales, Enterococcus spp., P. aeruginosa, Staphylococcus spp. and Streptococcus spp., respectively, resulting in an acceptable overall CA for all groups. (Very) major error rates were ≤ 5% for all antibiotics. Antibiotic disk thermostability was confirmed up to 4 days in the WASP Radian® In-Line Carousel. The Radian® In-Line Carousel provides a fully automated solution for accurate disk diffusion AST, reducing workload and improving standardization and traceability. In addition, our study demonstrated the thermostability of antibiotic disks up to 4 days in the WASP Radian® In-Line Carousel.

Self‐Assembled Molecules Fostering Ordered Spatial Heterogeneity for Efficient Ruddlesden‐Popper Perovskite Solar Cells

Abstract2D Ruddlesden‐Popper perovskites (RPP) with formamidinium‐cesium (FAC) alloyed cations possess powerful thermal‐moisture stability. However, their photovoltaic performance is hindered by the elusive spatial heterogeneity at multiscale lengths, highly associated with their coupled charge selective contacts. Herein, it reports on how the rational formation of self‐assembly molecules (SAMs) govern the orderliness of the spatial heterogeneity and crystal growth model in FACs‐RPP films, which is proposed to dictate the charge‐carrier dynamics. Unlike the disordered RPP film driven by the amorphous polymeric contacts, the laterally ordered crystallized SAM contacts facilitate a spatially ordered 2D/3D heterogeneity of FACs‐RPP film in long range, where distinct minor 2D phases are tightly coupled in short range. Such ordered heterogeneity can improve the energy transfer efficiency, facilitating the charge‐carrier dynamics in a well‐aligned 2D/3D landscape is discovered. Finally, the champion solar cells using selective SAM‐based FACs‐RPP films (n = 5) yield an efficiency of 18.85% (certified 18.19%) and excellent damp‐heat/operational stability, ranking in the top league of reported 2D RPP solar cells. More importantly, this SAM‐based principle can be adapted to diverse 2D structures, active areas, and substrate types. This work provides design directions for leveraging bottom‐selective contacts to tune spatial heterogeneity in state‐of‐the‐art 2D RPP optoelectronics.

Heterogeneity and wage growth of full-time workers in Japan: An empirical analysis using micro data

In this paper we examine the driving forces of fluctuations in wage growth of full-time workers in Japan, taking into account the heterogeneity of wage structures among the workers and using micro data including those from the Basic Survey on Wage Structure. To this end, we first divide full-time workers into two classes with distinct wage structures, based on a finite mixture model estimated using various characteristics of the workers and the firms they work for. We find that the two classes correspond to what previous studies have called an "internal labor market," where labor is reallocated within firms and wages follow a seniority-based system under long-term employment practices, and an "external labor market," where labor moves across firms and wages are mainly determined by supply and demand factors in the market. We next analyze the effects of economic factors on individual full-time workers' wage growth rates. We show that in the internal labor market, neither labor market conditions at the industry and firm-size level nor the output gap at the macro level have influenced the wage growth rates in recent years at least until 2021, while higher potential growth has increased them. By contrast, in the external and the overall labor markets for full-time workers, improvements in labor market conditions and the output gap have accelerated the wage growth rates, even in recent years.

Self-assembled complexing agent assisted chemical bath deposition of SnOX enabled highly efficient perovskite solar cells

Chemical bath deposition (CBD) is generally used to fabricate SnOX electron transport layer (ETL) for perovskite solar cells, whereas a lack of understanding of the reaction mechanism hampers further improvement of device performance. Here, we elucidate the reaction mechanism by monitoring the SnOX growth process via a series of advanced X-ray photoelectron spectroscopy studies. For the first time, we successfully modulated the nucleation and crystal growth of SnOX during the CBD process by introducing complexing agent via inherently forming a self-assembled monolayer on the outmost surface of SnOX. The complexing agents can assist the heterogeneous nucleation and crystal growth of SnOX. By a comparison study of different complexing agents, we found that the 2,3-dimercapto-1-propanesulfonate sodium not only assists in achieving a high-quality SnOX ETL, but also serves as a bridge to connect with perovskite via coordination interactions. Leveraging these insights, we achieved a champion efficiency of 24.2 % for perovskite solar cells with ∼ 2300 h stability at ambient condition.

Surface diffusion effects on the system and the film properties of a Ziff–Gulari–Barshad type growth model

Surface diffusion stands as a fundamental process influencing the dynamics and thermodynamics of surface reactions, playing a pivotal role in the behavior of heterogeneous catalysis and thin film growth. To enhance our understanding, we extend the Ziff-Gulari-Barshad (ZGB) growth model by incorporating the diffusion of reactants involved in film formation. Initially, in the realm of heterogeneous catalysis, we compare our findings with an extended ZGB model that accounts for reactant diffusion. We analyze the shift in phase transition positions, induced by diffusion, in comparison to the original ZGB model. Subsequently, we integrate the film growth aspect. Across all examined cases, diffusion fails to adequately preserve the dynamic features of the extended ZGB model, resulting in poisonous states. Our conclusion underscores the dual impact of diffusion: firstly, it diminishes the film growth rate relative to the diffusionless scenario, and secondly, its effective influence on the final film height is evident only when considering hops in different layers. This assertion is validated through computations where diffusion with hops in different layers is either permitted or prohibited.

Hollow-structured covalent organic framework decorated with FA-PEG: A biocompatible nanocarrier for targeted and pH-responsive release of doxorubicin

Hollow nanostructures hold great promise for drug delivery applications due to their considerable capabilities for efficient drug encapsulation alongside distinct physicochemical attributes. Herein, an imine-linked hollow nanosphere covalent organic framework (COF) with high surface area and well-structured porosity was developed serving as a versatile drug delivery system (DDS) to achieve targeted and effective delivery of doxorubicin (DOX) as a chemotherapeutic agent. The production of COF hollow nanoparticles included the use of a heterogeneous nucleation and growth method, followed by the subsequent encapsulation of DOX. Following this, the nanoparticles underwent functionalization with folate-poly (ethylene glycol)-amine (FA-PEG) using a bonding defect strategy. An in vitro cytotoxicity assay and flow cytometry study against FR-negative HEK293 and FR-positive MCF7 cells were performed, revealing that FA-PEG-functionalized HCOF exhibited a unique targeting effect on cancer cells, surpassing the impact of DOX@HCOF on FR-positive MCF7 cancer cells. Additionally, the hollow architecture of the COF is engineered to undergo disintegration selectively under conditions of cancer cell pH, facilitating the comprehensive release of DOX. The pH-responsive and tumor-targeted attributes of the DOX@HCOF-PEG-FA open new avenues for incorporating structural engineered HCOFs as a promising drug carrier capable of regulating drug release and augmenting therapeutic efficacy.

The mechanistic origins of heterogeneous void growth during ductile failure

In 1969, Rice and Tracey proposed that the rate of void growth during ductile failure is a strong function of the hydrostatic stress state. Numerous in-situ x-ray computed tomography (XCT) studies demonstrated that the average rate of void growth is well-predicted by modified versions of the Rice-Tracey equation. However, recent in-situ XCT studies of void growth demonstrated that individual voids grow in highly heterogeneous manners in a way that is not predicted by Rice-Tracey or similar models. Model-based studies using crystal plasticity finite element (CP-FE) suggest that local effects of grain orientation play a strong role during void growth, but we lack experimental data to test this hypothesis. The present study leverages recent advances in laboratory-based diffraction contrast tomography (Lab-DCT) and in-situ XCT to systematically examine the effects of grain orientation on void growth experimentally in an Al-2219 alloy. CP-FE modeling was used to assess the local stress states associated with voids and their influence on void growth rates. These data indicate that void growth is not simply controlled by the local hydrostatic stress or stress triaxiality. Additionally, no clear relationship between void growth rates and grain orientation were observed. Instead, void growth rates were highly stochastic in ways that could not be directly linked to the local stress or strain states. The combination of experimental and modeling data suggests that our current assumptions regarding the mechanisms of void growth are flawed and that additional factors, which may include the local dislocation density, affect the rate of void growth.

Abnormal H3K4 enzyme catalytic activity and neuronal morphology caused by ASH1L mutations in individuals with Tourette syndrome.

ASH1L potentially contributes to Tourette syndrome (TS) and other neuropsychiatric disorders, as our previous studies have shown. It regulates essential developmental genes by counteracting polycomb-mediated transcriptional repression, which restricts chromatin accessibility at target genes. ASH1L is highly expressed in the adult brain, playing a crucial role in the early stage. However, it remains unclear how ASH1L mutations carried by patients with TS participate in regulating neuronal growth processes leading to TS traits. Five TS families recruited in our study underwent comprehensive physical examinations and questionnaires to record clinical phenotypes and environmental impact factors. We validated the variants via Sanger sequencing and constructed two mutants near the catalytic domain of ASH1L. We conducted molecular modeling, in vitro assays, and primary neuron cultures to find the role of ASH1L in neuronal development and its correlation with TS. In this study, we validated five pathogenic ASH1L rare variants and observed symptoms in patients with simple tics and behavioral comorbidities. Mutations near the catalytic domain of TS patients cause mental state abnormalities and disrupt ASH1L function by destabilizing its spatial conformation, leading to decreased activity of catalytic H3K4, thereby affecting the neurite growth. We need to conduct larger-scale studies on TS patients and perform additional neurological evaluations on mature neurons. We first reported the effects of ASH1L mutations in TS patients, including phenotypic heterogeneity, protein function, and neurological growth. This information contributes to understanding the neurodevelopmental pathogenesis of TS in patients with ASH1L mutations.

A numerical model for investigating the effect of material and process parameters on the running of flash sintering

Flash sintering of ceramic powders is a complex process that involves electric, thermal and mechanical phenomena. Modelling should help to better understand and control it, with a view to producing safe and homogeneous parts. A finite element model that couples all relevant phenomena, including the densification and shrinkage of the sintering material, has been worked out for this purpose. This model is used here to investigate the flash sintering of disk-shaped parts. Particular attention is paid to the appearance and growth of heterogeneities within the part, known as hot spots, which are highly dependent on material and process parameters. Leads are provided for limiting the development of such heterogeneities.

An innovative strategy to prepare fine-grained Mg-Al alloys with a superior strength-ductility synergy via wire-arc directed energy deposition

Fine grain structures are necessary in obtaining superior mechanical properties of Mg alloys fabricated by wire-arc directed energy deposition (DED), which is still challenging nowadays. In the present work, a novel strategy by the synergistic effect of arc oscillation and feeding of SiC particles (SiCps), i.e., WADED-OS, has been proposed, which is extremely effective in grain refinement of the AZ31 thin-wall component. The average grain size of the WADED-OS AZ31 thin-wall component (∼19 μm) decreases by ∼81% compared to the counterpart fabricated via conventional straight deposition (∼102.4 μm). Introducing arc oscillation can reduce the temperature gradient in the molten pool, which promotes the transition from columnar grains to equiaxed grains. At the same time, the incorporation of SiCps can decrease the average grain size due to the heterogeneous nucleation and grain growth inhibition effects. The thin-wall component produced via the novel WADED-OS strategy exhibits a superior combination of strength and ductility, i.e., the ultimate tensile strength and elongation are 265 ± 2 MPa and 19.8 ± 2.3% along the deposition direction, respectively. This study proposes an innovative strategy for achieving wire-arc DED Mg alloy components with fine microstructures and superior mechanical properties.

Evaluation of PlanetScope-detected plant-specific phenology using infrared-enabled PhenoCam observations in semi-arid ecosystems

Phenology detection from remotely sensed data remains challenging in semi-arid ecosystems due to the unique spatial heterogeneity and irregular temporal growth in plants. PlanetScope imagery, with fine spatial and temporal resolutions, is revolutionizing the earth observation sector. It has demonstrated its effectiveness in monitoring phenology dynamics across various terrestrial ecosystems. However, the quality and accuracy of PlanetScope data for depicting plant growth development and detecting phenological metrics (phenometrics) in semi-arid environments have not been systematically examined. In this study, we evaluated the capability of PlanetScope for monitoring plant-specific phenology across the semi-arid western United States, by comparing phenometrics (onsets of greenup, maturity, senescence, and dormancy) retrieved from time series of two PlanetScope vegetation indices (VI), which are EVI2 (two-band Enhanced Vegetation Index) and NDVI (Normalized Difference Vegetation Index), with a set of PhenoCam observations at 15 sites. To conduct a comprehensive comparison, PhenoCam time series and phenometrics were extracted from infrared-enabled PhenoCam EVI2 and NDVI, as well as commonly used PhenoCam GCC (Green Chromatic Coordinate). Our results show that (1) time series of PlanetScope VI were consistent with PhenoCam GCC and VI time series during greenup phase but moderately comparable during senescence phase, with an average R2 of 0.67 and 0.57 for greenup and senescence phases, respectively; (2) phenometrics derived from PlanetScope VI exhibited better agreement with those from PhenoCam GCC and VI in greenup phase (greenup and maturity onsets) than in senescence phase (senescence and dormancy onsets), with an average R2 of 0.81, 0.84, 0.72, and 0.53 for greenup, maturity, senescence, and dormancy onsets, respectively; (3) PlanetScope-detected senescence onset and dormancy onset were systematically later than PhenoCam-based retrievals with a mean systematic bias of 12.6 days and 18.2 days, respectively; (4) phenometrics derived from PlanetScope VI were more comparable with PhenoCam VI retrievals than with PhenoCam GCC retrievals, which are reflected in better correlations and smaller bias between phenometrics, especially during senescence phase; and (5) PlanetScope and PhenoCam EVI2 time series produced the most comparable phenometrics, suggesting that EVI2 is an optimal index for vegetation phenology detections from different sensors. In summary, this study suggests PlanetScope has the ability to detect plant-specific phenology and to improve our understanding of phenology dynamics in heterogeneous semi-arid ecosystems at fine scales.

Layer-by-layer growth of Cu3(HHTP)2 films on Cu(OH)2 nanowire arrays for high performance ascorbic acid sensing

Growing three-dimensional (3D) metal organic frameworks (MOFs) via heterogeneous epitaxial growth on metal hydroxide arrays are effective for constructing electrochemical sensor. However, the growth of MOFs is difficult to control, resulting in thick and irregular morphologies and even damage the metal hydroxide template. In this work, Cu3(HHTP)2 (HHTP = 2, 3, 6, 7, 10, 11-hexahydroxytriphenylene) films with controllable thickness and morphology were successfully prepared on Cu(OH)2 nanowire arrays (NWAs) through layer-by-layer (LBL) growth method. We have discovered that the LBL cycle and the reaction solvent composition are crucial for growing homogenous MOF thin films. The Cu3(HHTP)2 based ascorbic acid (AA) sensor, fabricated in ethanol within 10 LBL cycles, generated an ultrahigh sensitivity of 821.64 μA mM−1 cm−2 in the range of 6–981.41 μM, a low detection limit of 60 nM as well as the great selectivity, stability and reproducibility. Moreover, the relative deviation for AA detection in two fruit juices were 3.22 % and 3.71 %, and the test result for human sweat fall within the normal AA concentration range, verifying the feasibility of as-prepared sensor for practical application.