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With the improvement of people's living standards and rice trade worldwide, the demand for high-quality rice is increasing. Therefore, breeding high quality rice is critical to meet the market demand. However, progress in improving rice grain quality lags far behind that of rice yield. This might be because of the complexity of rice grain quality research, and the lack of consensus definition and evaluation standards for high quality rice. In general, the main components of rice grain quality are milling quality (MQ), appearance quality (AQ), eating and cooking quality (ECQ), and nutritional quality (NQ). Importantly, all these quality traits are determined directly or indirectly by the structure and composition of the rice seeds. Structurally, rice seeds mainly comprise the spikelet hull, seed coat, aleurone layer, embryo, and endosperm. Among them, the size of spikelet hull is the key determinant of rice grain size, which usually affects rice AQ, MQ, and ECQ. The endosperm, mainly composed of starch and protein, is the major edible part of the rice seed. Therefore, the content, constitution, and physicochemical properties of starch and protein are crucial for multiple rice grain quality traits. Moreover, the other substances, such as lipids, minerals, vitamins, and phytochemicals, included in different parts of the rice seed, also contribute significantly to rice grain quality, especially the NQ. Rice seed growth and development are precisely controlled by many genes; therefore, cloning and dissecting these quality-related genes will enhance our knowledge of rice grain quality and will assist with the breeding of high quality rice. This review focuses on summarizing the recent progress on cloning key genes and their functions in regulating rice seed structure and composition, and their corresponding contributions to rice grain quality. This information will facilitate and advance future high quality rice breeding programs.

The effect of grain size heterogeneity on the mechanical and microcracking behavior of Lac du Bonnet (LdB) granite during heating, cooling, and uniaxial compression loading is investigated using a grain-based model. By defining a grain size heterogeneity index H, the heterogeneity induced by variation of grain size distribution can be explicitly incorporated into the grain-based model quantitatively. Five modelled LdB granite samples with different grain size heterogeneity indices ranging 0.19–1.22 are established. The results suggest that the grain size heterogeneity and treatment temperature have critical impacts on the mechanical properties of modelled LdB granite samples. With the increase of temperature and grain size heterogeneity index, the mechanical properties show a decreasing trend. Several empirical formulations are developed to predict the temperature-dependent mechanical properties of modelled LdB granite samples with different grain size heterogeneity indices. Generally, modelled LdB granite samples with greater grain size heterogeneity index has a lower temperature of brittle-ductile transition. In terms of microcracking behavior, both temperature and grain size heterogeneity affect it, including number, density, orientation, and distribution. As the temperature increases, the number and related density of thermal stress-induced cracks increase. Generally, the amount of thermal stress in modelled LdB granite samples during heating increases with the increases of grain size heterogeneity index. The controlling factor of the failure pattern of samples gradually changes from the presence of thermal stress-induced cracks to grain size heterogeneity as the model progresses from relatively homogeneous (H ranging 0.19–0.76) to heterogeneous (H ranging 0.93–1.22).HighlightsExplicitly incorporate grain size heterogeneity induced by grain size distribution into a grain-based model.Reveal the effect of grain size heterogeneity on mechanical properties and microcracking behavior of Lac du Bonnet granite at different temperatures.Propose empirical formulations to quantify the temperature-dependent mechanical properties of Lac du Bonnet granite with grain size heterogeneity index.

A comprehensive understanding of the deposition mechanisms and morphology of debris flows is necessary to delineate the extent of a debris flow hazard. However, due to the wide range of debris flow compositions and the complex topography in the field, there remains a deficiency of fundamental understanding on how the effects of grain-size distribution, water content, and channel slope influence the deposition mechanisms and morphology of debris flow. In this study, a series of experimental tests were carried out using a flume with a horizontal outflow plane to discern the effects of particle size, water content, and slope on the deposition morphology and grain size segregation on the deposition fan. Results reveal that the experimental debris flows are under either viscous or collisional flow regimes. Most experimental debris flow fronts lack high pore fluid pressures, emphasizing the formation of deposits via grain-grain and grain-bed friction and collisions; also high excess pore fluid pressure (positive) behind the front head is measured and it is beneficial for the mobility of debris flows. Both the deposit area and runout-width ratio are positively correlated to the Bagnold and Savage numbers and the initial water contents. Furthermore, an increase of fines content reduces the runout distance. However, this feature is not as obvious for high water content flows (w = 28.5% in this study). Moreover, smoother transition topography between the transportation and deposition zone leads to longer runout distances. For debris flows with a high solid fraction (Cs > 0.52 in this study), particle sorting is quite inhibited in the deposit fan.

Dissolved oxygen (DO) level at the sediment–water interface is one key factor controlling redox-sensitive processes, such as nutrient cycling. Microcosm experiments with sediment collected from three reservoirs were performed to quantify the influences of water column oxygenation (oxic, anoxic, oxygen fluctuation), sediment characteristics (grain size distribution, total nitrogen and total phosphorus contents, microbial activities), and their interactions on nutrient fluxes from sediments to the water column. Algal growth bioassays were also performed using water from the microcosms to determine which conditions produced the most favorable growth conditions. Anoxic conditions increased the release of dissolved inorganic nitrogen (DIN), mainly as ammonium and phosphates, compared to the other DO conditions. Such effects were likely due to an inhibition of the nitrification–denitrification coupling process for DIN and a reductive dissolution of Fe (III) oxides for phosphates. Following this increased nutrient availability, algal growth in the bioassays was the highest in water collected from microcosms exposed to anoxic conditions. Under both oxic and anoxic conditions, the percentage of fine sediment particles led to decreasing DIN and phosphates fluxes by reducing the nutrient diffusion rate from sediments to the water column. Finally, both DO and sediment grain size controlled the contribution of sediments to reservoir eutrophication.

Summary Enhanced grain yield and quality traits are everlasting breeding goals. It is therefore of great significance to uncover more genetic resources associated with these two important agronomic traits. Plant MYB family transcription factors play important regulatory roles in diverse biological processes. However, studies on genetic functions of MYB in rice yield and quality are rarely to be reported. Here, we investigated a nucleus‐localized transcription factor OsMYB73 which is preferentially expressed in the early developing pericarp and endosperm. We generated targeted mutagenesis of OsMYB73 in rice, and the mutants had longer grains with obvious white‐belly chalky endosperm appearance phenotype. The mutants displayed various changes in starch physicochemical characteristics and lipid components. Transcriptome sequencing analysis showed that OsMYB73 was chiefly involved in cell wall development and starch metabolism. OsMYB73 mutation affects the expression of genes related to grain size, starch and lipid biosynthesis and auxin biosynthesis. Moreover, inactivation of OsMYB73 triggers broad changes in secondary metabolites. We speculate that rice OsMYB73 and OsNF‐YB1 play synergistic pivotal role in simultaneously as transcription activators to regulate grain filling and storage compounds accumulation to affect endosperm development and grain chalkiness through binding OsISA2, OsLTPL36 and OsYUC11. The study provides important germplasm resources and theoretical basis for genetic improvement of rice yield and quality. In addition, we enriches the potential biological functions of rice MYB family transcription factors.

In this paper we will review some of the many achievements of Statistical Theory of Grain Growth (which is 40 years old, this year!), based on the classic law of grain growth. For instance, we will show that grain growth in presence of texture (which is the usual feature in a real microstructure) is not exclusively depending on the curvature of the grain boundary, as in this case the effect of curvature at the vertexes (in 2-D case) contributes as well (which, depending on the texture pattern, sometimes may be more relevant than curvature along the boundary). Such phenomenon requires a reformulation of Von Neuman’s equation in 2-D by involving, beside the different boundary mobilities, the different energies of the “third” grain boundary, which is pulling the vertex and inducing an extra curvature which is not balanced along the grain perimeter (for simplicity’s sake we are referring to a 2-D case, but the analysis can also be done in 3-D). We can then observe that boundary movement is not only depending on a couple of grains in contact (with the boundary curvature acting like in a bicrystal) but also includes the network of “third” grains operating at the vertexes. The overall consequence is that the growth kinetics and the grain size distribution shape are unique and variable for each texture component which contradicts classic growth laws as well as the expected results for the whole grain size distribution.

Regional grain size trends in fluvial successions can reveal important information regarding the dynamics of sediment routing systems. Self‐similar solutions for down‐system grain size fining have recently been proposed to explore how key variables, such as the spatial distribution of deposition, sediment discharge, and sediment supply characteristics, control spatial distribution of grain size in fluvial successions over time scales of 104–106 years. We explore the sensitivity of these solutions to changes in key variables and assess their applicability to ancient fluvial successions. Several sensitivity analyses are presented to investigate the relative control of the key model variables on the spatial pattern of down‐system grain size fining in fluvial successions. Sensitivity analyses demonstrate that (1) an increase in the initial value of sediment discharge to a basin causes a decrease in the rate of grain size fining in fluvial successions, an effect that becomes nonlinear for large values of initial sediment discharge; (2) a short‐wavelength/high‐amplitude subsidence regime generates a greater rate of down‐system grain size fining and a long‐wavelength/lower‐amplitude subsidence regime generates a lesser rate of down‐system grain size fining in fluvial successions; and (3) an increase in the spread of grain sizes in the sediment supply generates a greater rate of down‐system grain size fining. We apply this modeling technique to grain size data sets collected from two time surfaces within conglomerates of the Upper Eocene Montsor Fan Succession of the Pobla Basin, Spanish Pyrenees. These data sets exhibit approximately self‐similar grain size distributions; further, the observed increase in down‐system grain size fining associated with smaller depositional system lengths provides support for the application of self‐similar solutions to fluvial successions. By applying these solutions to carefully collected grain size data from fluvial successions, we are able to relate explicitly the initial grain size supplied to the system, the spatial distribution of subsidence and the sediment discharge into the basin to the rate of grain size fining in fluvial successions. This method thus offers a powerful means of elucidating sediment routing system dynamics over time.

Planetary bodies are formed by coagulation of solid dust grains in protoplanetary disks. Therefore, it is crucial to constrain the physical and chemical properties of the dust grains. In this study, we measure the dust albedo at millimeter wavelength, which depends on dust properties at the disk midplane. Since the albedo and dust temperature are generally degenerate in observed thermal dust emission, it is challenging to determine them simultaneously. We propose to break this degeneracy by using multiple optically thin molecular lines as a dust–albedo-independent thermometer. In practice, we employ pressure-broadened CO line wings that provide an exceptionally high signal-to-noise ratio as an optically thin line. We model the CO J = 2–1 and 3–2 spectra observed by the Atacama Large Millimeter/submillimeter Array at the inner region (r < 6 au) of the TW Hya disk and successfully derive the midplane temperature. Combining multiband continuum observations, we constrain the albedo spectrum at 0.9–3 mm for the first time without assuming a dust opacity model. The albedo at these wavelengths is high, ~0.5–0.8, and broadly consistent with the L. Ricci et al., DIANA, and DSHARP dust models. Even without assuming dust composition, we estimate the maximum grain size to be ~340 μm, the power-law index of the grain size distribution to be >−4.1, and the porosity to be <0.96. The derived dust size may suggest efficient fragmentation with a threshold velocity of ~0.08 m s−1. We also note that the absolute flux uncertainty of ~10% (1σ) is measured and used in the analysis, which is approximately twice the usually assumed value.

Nano-grained (NG) metals are believed to be strong but intrinsically brittle: Free-standing NG metals usually exhibit a tensile uniform elongation of a few percent. When a NG copper film is confined by a coarse-grained (CG) copper substrate with a gradient grain-size transition, tensile plasticity can be achieved in the NG film where strain localization is suppressed. The gradient NG film exhibits a 10 times higher yield strength and a tensile plasticity comparable to that of the CG substrate and can sustain a tensile true strain exceeding 100% without cracking. A mechanically driven grain boundary migration process with a substantial concomitant grain growth dominates plastic deformation of the gradient NG structure. The extraordinary intrinsic plasticity of gradient NG structures offers their potential for use as advanced coatings of bulk materials.

The Sentinel Application Platform (SNAP) architecture facilitates Earth Observation data processing. In this work, we present results from a new Snow Processor for SNAP. We also describe physical principles behind the developed snow property retrieval technique based on the analysis of Ocean and Land Colour Instrument (OLCI) onboard Sentinel-3A/B measurements over clean and polluted snow fields. Using OLCI spectral reflectance measurements in the range 400–1020 nm, we derived important snow properties such as spectral and broadband albedo, snow specific surface area, snow extent and grain size on a spatial grid of 300 m. The algorithm also incorporated cloud screening and atmospheric correction procedures over snow surfaces. We present validation results using ground measurements from Antarctica, the Greenland ice sheet and the French Alps. We find the spectral albedo retrieved with accuracy of better than 3% on average, making our retrievals sufficient for a variety of applications. Broadband albedo is retrieved with the average accuracy of about 5% over snow. Therefore, the uncertainties of satellite retrievals are close to experimental errors of ground measurements. The retrieved surface grain size shows good agreement with ground observations. Snow specific surface area observations are also consistent with our OLCI retrievals. We present snow albedo and grain size mapping over the inland ice sheet of Greenland for areas including dry snow, melted/melting snow and impurity rich bare ice. The algorithm can be applied to OLCI Sentinel-3 measurements providing an opportunity for creation of long-term snow property records essential for climate monitoring and data assimilation studies—especially in the Arctic region, where we face rapid environmental changes including reduction of snow/ice extent and, therefore, planetary albedo.