Medium Grain Research Articles

Multi-grain reconfigurable and scalable overlays for hardware accelerator composition

In this paper, the reconfigurable nature of SRAM-based FPGAs is exploited to build a dynamically multi-grain reconfigurable and scalable overlay architecture. The composition of the overlay can be reconfigured on the fly to map applications with different requirements, change the size of the overlay to free up resources for other accelerators, or to deal with run-time variable computation demands. The overlay has been implemented by combining two different dynamic partial reconfiguration granularities. First, medium grain is used to compose the overlay by stitching together different processing elements, while fine grain reconfiguration is used to map applications onto the overlay by configuring the interconnections of the processing elements. The overlay has been coupled with a multiport memory and integrated into a System-on-Chip (SoC). Finally, a fully automated toolchain is proposed to transform code segments with one or two nested loops into the appropriate overlay configuration and the required control routines, enabling the transparent offloading of the computing-intensive parts of the application from the embedded SoC processor to hardware. The proposed overlay has been implemented in a Xilinx Zynq-7000 device and tested using the benchmark proposed in the CGRA-ME framework, obtaining up to 2 × speed-up.

Petrography and Geochemistry of Dolomites of Samanasuk Formation, Dara Adam Khel Section, Kohat Ranges, Pakistan

Replacement dolomite occurs in Jurassic Samanasuk Formation in Dara Adam khel area of Kohat ranges, North-Western Himalayas, Pakistan. This study, for the first time, document the process of dolomitization and evolution of strata bound dolomitic bodies. Field investigation, petrography and geochemistry helped in unraveling the formation of several dolomitic bodies. Petrographically dolomites comprises of: (1) medium grain crystalline planer subhedral dolomite (Dol-I); (2) fine grained crystalline anhedral non-planer dolomite rhombs (Dol-II); (3) medium to coarse grained crystalline subhedral-anhedral non-planer dolomite (Dol-III) and coarse to very coarse grained crystalline saddle dolomite cements (SD). The saddle dolomites (SD) postdate the replacement dolomites and precede telogenetic calcite (TC) cements. Stable O and C isotope analysis shows that these dolomites have δ18Ovpdb ranging from -4.09% to -10.4 whereas the δ13Cvpdb ranges from +0.8 to +2.51. Major and trace elements data show that Sr concentrations of 145.5 to 173 ppm; Fe contents of 2198 to 8215 ppm; and Mn contents of 93.5 to 411 ppm. Petrographically replacive dolomites, saddle dolomite, and δ18Ovpdb values depicts neomorphism of replacement dolomites that were formed earlier were exposed to late dolomitizing fluids. As a result of basin uplift during the Himalayan orogeny in Eocene time, dolomitization event was stopped through occurrence of meteoric water. The Main Boundary Thrust (MBT) and its splays were most likely essential conduits that channelized dolomitizing fluids from siliciclastic rocks that were buried deeply into the Jurassic carbonates rocks, leading to more extreme dolomitization.

Acceleration and clustering of cosmic dust in a gravoturbulent gas I. Numerical simulation of the nearly Jeans-unstable case

ABSTRACT We investigate the dynamics of interstellar dust particles in moderately high resolution (5123 grid points) simulations of forced compressible transonic turbulence including self-gravity of the gas. Turbulence is induced by stochastic compressive forcing which is delta-correlated in time. By considering the nearly Jeans-unstable case, where the scaling of the simulation is such that a statistical steady state without any irreversible collapses is obtained, we obtain a randomly varying potential, acting as a second stochastic forcing. We show that, in this setting, low-inertia grains follow the gas flow and cluster in much the same way as in a case of statistical steady-state turbulence without self-gravity. Large, high-inertia grains, however, are accelerated to much higher mean velocities in the presence of self-gravity. Grains of intermediate size also show an increased degree of clustering. We conclude that self-gravity effects can play an important role for aggregation/coagulation of dust even in a turbulent system which is not Jeans-unstable. In particular, the collision rate of large grains in the interstellar medium can be much higher than predicted by previous work.

Geophysical Investigations and Aquifer Characteristics of the Benin Formation at Agbarho, Delta State, Nigeria

Groundwater investigations were carried out at Agbarho using geophysical survey method to delineate the aquifer and subsurface lithology. Three (3) vertical electrical sounding were conducted with a maximum current electrode spacing of 300m. The data acquired were subjected to partial curve matching and computer processing. The results delineated five geoelectric layers for the area, which include; topsoil, silty sand, silty clay, fine sand, medium grain sand and coarse sand. The Dar-Zarrouk parameter revealed an aquifer system that has a resistivity values ranging from 503.9-966.9ohm-m, an average hydraulic conductivity of 7.73 m/day, and transmissivity in the range of 156.24-181.44m2/day. The depth to the aquifer range from 13.2-42.7m and the aquifer thickness is between 7-36.7m. Results from seven down-hole logs revealed the presence of silty sand, fine sand and fine-medium grained sand. The transmissivity values from pumping test range from 162.29-286.56m2/day and storativity is from 0.001-0.00838. The aquifer is capable of yielding useful quantity of water to the wells and sustainable groundwater management plan can be develop for the area.

Particle-Size Fractionation and Thermal Variation of Oil Shales in the Songliao Basin, NE China: Implication for Hydrocarbon-Generated Process

The synchronous variation and association of organic matter (OM) and minerals in the hydrocarbon-generated process of oil shales are poorly understood. The goal of the paper is to investigate OM occurrence and thermal variation so as to reveal the hydrocarbon generation potential of oil shales. Based on detailed analyses of particle, organic, mineral, and thermal data from lacustrine oil shales in the Songliao Basin, we observed three layers of shale particles after settling in the water column characterized by a distinct color, degree of consolidation, and particle size. The particle sizes are divided into three ranges of fine grain (<1 μm), medium grain (1–20 μm), and coarse grain (>20 μm) via laser particle analysis. The particle-size distribution indicates the presence of OM polymerization and dominant contribution of the associated mineral surface and bioclastic OMs to the OM abundance of oil shale. Various OM occurrences are influenced by OM sources and redox conditions, whereas the degree of biodecomposition and particle sizes affect the placement of OM occurrences. Based on multiple thermal analyses, a synchronous response of OM and minerals to thermal variation dominates at 300–550 °C. The I/S and chlorite minerals are characterized by an entire illitization, while solid/absorbed OMs and hydrocarbon-generated water were expelled in large quantities. This contributes to major loss weights of oil shales during heating. The peak hydrocarbon-generated rate occurred at 457 °C for oil shales, corresponding to around 1.3% vitrinite reflectance value. These results are suggested to improve the understanding of OM occurrences and the thermal degradation constraint on the hydrocarbon-generated process, and contribute to the interpretation of the hydrocarbon generation potential and in-situ exploitation of oil shales.

Coastal morphodynamic analysis in Buleleng Regency, Bali—Indonesia

Sediment as erosion product can affect shorelines, making sediment transport a key process to consider in coastal and shoreline management. Field surveys and secondary data can identify where suspended matters are distributed and deposited to analyze sediment uniformity factors: beach morphology and materials. This research set out to determine the Buleleng Regency's morphodynamic aspects based on the coastal landscape's physical characteristics and the processes acting upon each sediment cell. Field observations were conducted at five stations, from Tukad Gerokgak to Tukad Saba estuary. Jaelani's spectral transformation has been applied to analyze Total Suspended Solids using Sentinel 2A imagery. The laboratory test results of grain-size samples were processed on GRADISTAT, then the depositional environment and sediment transport direction were determined from average grain size, standard deviation, skewness, and kurtosis. Shoreline change, an indicator of coastal morphodynamics, was mapped from Landsat images in 2000, 2008, and 2019 using the Digital Shoreline Analysis System. Statistical analysis on GRADISTAT provided details on depositional environment and sediment transport and deposition based on grain-size distribution. Results indicate poorly sorted medium grain size: gravel (stone) to coarse sand, making up the sediment population from Tukad Gerokgak to Tukad Saba. Generally, sediment is deposited toward coarse, even very coarse, grain on a strongly sloping beach, and there is a high likeliness of sediment accretion. Identified morphodynamic characteristics suggest that the coastal landscape needs structural mitigation to overcome the accelerating impact of human activities and physical processes.

Aromatic Rice with Multiple Disease Resistance Developed through Anther Culture

The experiments were conducted during kharif (June to September) 2018 and 2019 to screen 7 aromatic rice double haploid (DH) lines developed against Bacterial Leaf Bligh (BLB) and blast disease. Three genes Xa21, xa13, xa5 for BLB resistance and two genes Pi1, Pi2 for blast resistance was introgressed into a local aromatic rice variety Dubraj from Chhattisgarh State of India. Dubraj is extremely popular aromatic short medium grain variety in Chhattisgarh and Madhya Pradesh region and hence used in this study. RPBIO-226 and PR122 rice variety is used as donor for BLB and blast resistance respectively. 7 DH lines (L-1 to L-7) were developed from the crosses (Dubraj X RPBIO-226 X PR122) in the year 2017. Phenotypic evaluation for BLB diseases resistance has shown that L-1, L-6 and L-7 (score 1) has a similar resistance as the control check RPBIO-226(score-1) and 3 lines with moderate resistance (L-3 score 2) (L-4 score 3) (L-5 score 3). For blast disease, three lines (L-4, L-6 and L-7) were identified as resistance with the disease score of 1, whereas three were grouped under the section moderately resistant (L-1, L-3 and L- 5) with a disease score of 3. Sensory test (1.7% KOH) was conducted for the estimation of presence / absence of aroma. Moderately strong aroma was present in four lines (L-1, L-3, L-6 and L-7). On the basis of yield and presence of aroma in grain, L-3 has been selected with moderately resistant to BLB and blast for further advancement and subsequently evaluated under State Initial Evaluation Trial (SIET) during kharif 2020. Within 3 years of development of DH line, L-3 is under varietal developmental trail, which itself indicate the efficacy of anther culture in fixing homozygosity and speedy development of desired variety within short period of time.

Grain-size effect on dynamic behavior of sandstone based on high-speed 3D-DIC technique

The grain size effect on the dynamic behavior of sandstone was investigated through the compression tests on coarse-grained (CG), medium-grained (MG) and fine-grained (FG) sandstones by split Hopkinson pressure bar (SHPB) tests under the strain rates of 69–83 s–1 based on the thin section and electron scanning microscopic (SEM) images analysis, the CG, MG and FG sandstone were mainly composed by quartz with the average grain size of 200–500, 90–500 and 55–120 µm, respectively. With the increasing grain size, the percentage of clay mineral was decreased correspondingly from 8% to 1%. During the dynamic compression, two high-speed cameras were applied to capture the deformation of sandstone at frame rate of 2×105 s–1 and resolution of 256×256. The real-time strain fields of rock were obtained by high-speed three-dimensional digital image correlation (3D-DIC) technique, the dynamic deformative properties, particularly the lateral strain of the specimen, were extracted by averaging the lateral strain field by pixels. The fracturing behavior of three sandstones was analyzed through the strain localization evolution within the strain fields. Results show that the critical strain rate for reversible release of elastic strain energy increases with the decreasing grain size. The dynamic strength ascends along with the reduction of grain size, while the strain rate sensitivity to the dynamic strength has an opposite trend. Compared to the quasi-static case, the dynamic elastic modulus increases by 2–3 times for MG and FG sandstone, particularly 5 times for CG sandstone. The Poisson’s ratio under dynamic loading in FG sandstone is grown by 25%, but drops at 70% of the static one in MG sandstone. The crack primarily generates inside the specimen and propagates to the surface of the specimen afterwards. The crack development is advanced under dynamic loadings, where the normalized stress threshold for crack initiation in FG sandstone is only 10%. Based on the microscopic analysis, mineral structure and clay percentage dominate the dynamic property and fracturing behavior of sandstone, respectively.

Effect of Dust Size on the Near-infrared Spectra (1.0–5.0 μm) of Brown Dwarf Atmospheres

Abstract In this study, we demonstrate the dependence of atmospheric dust size on the near-infrared spectra of ten L dwarfs, and constrain the sizes of dust grains in each L dwarf atmosphere. In previous studies, by comparing observed and modeled spectra, it was suggested that the deviations of their spectral shapes from theoretical prediction are general characteristics. Here, we focus on the dust size in brown dwarf atmospheres to understand the observed spectra. We confirm that changing the dust size changes the temperature–pressure structure of the atmosphere, with the shape of the spectrum changing accordingly. At the wavelength at which dust is the main absorber of radiation (the dust-dominated regime), a large dust opacity combined with a medium grain size, e.g., 0.1 μm, results in a low photospheric temperature, and thus a small flux. Conversely, for the wavelength at which gas absorption is dominant (the gas-dominated regime), a large dust opacity modifies the temperature–pressure structure, resulting in a high photospheric temperature, which corresponds to large flux emissions. Taking into account the size effect, we compare the model spectral fluxes in the wavelength range 1–5 μm with the observational ones to constrain the main dust size in the atmosphere of each of the ten L dwarfs observed with AKARI and SpeX or CGS4. Ultimately, we reveal that the observed data are reproduced with higher fidelity by models based on a medium dust size of 0.1–3.0 μm for six of these L dwarfs; therefore, we suggest that such atmospheric dust sizes apply to the majority of L dwarfs.

Effect of binder saturation and drying time on microstructure and resulting properties of sinter-HIP binder-jet 3D-printed WC-Co composites

Binder-jet 3D-printing, a non-beam-based additive manufacturing method, is a process of selectively joining layers of powder using a polymeric binder. In this study, the effects of print processing parameters such as binder saturation (60–250%) and drying time (30–45 s) on 3D-printed WC-Co composite powder is studied. Densification is attained by sintering under a vacuum atmosphere to reach the maximum temperature of 1435 ℃ followed by hot isostatic pressing under a pressure of 6.1 MPa. Although the green density of the 3D printed samples was ~21–23%, solid volume fraction of 97% to nearly 100% and near theoretical densities of 14.10–14.35 g/cm3 were achieved depending on the print processing parameters. Microstructural characterization of the final parts reveals potential spreading defects appearing as remnant pores formed during printing at a higher binder saturation level. Additionally, Co-rich pools also appear in the final parts. X-ray diffraction shows WC and Co as the main phases and a potential η-phase formation depending on the binder saturation level. Parts with WC grain size of 1.6 ± 0.7 µm, average Vickers hardness of 1270–1320 HV60 and fracture toughness of 17–22 MPa m1/2 are attained, similar to conventionally produced WC-Co with medium grain size. Here, binder-jet 3D-printing is used to fabricate WC-Co parts with uniform microstructure and mechanical properties.

Consumer Acceptance of Brown and White Rice Varieties.

Rice is consumed as a staple food by more than half of the world’s population. Due to a higher fibre and micronutrient content, brown rice is more nutritious than white rice, but the consumption of brown rice is significantly lower than that of white rice, primarily due to sensory attributes. Therefore, the present research aimed to identify the sensory attributes which drive liking of Australian-grown brown and white rice varieties. Participants (n = 139) tasted and scored (9-point hedonic scale) their liking (i.e., overall liking, aroma, colour and texture) of brown and white rice types of Jasmine (Kyeema), Low GI (Doongara), and Medium grain rice (Amaroo). In addition, participants scored aroma, colour, hardness, fluffiness, stickiness, and chewiness, on Just About Right Scales. A within-subjects crossover design with randomised order (William’s Latin Square design) was used with six repeated samples for liking and Just About Right scales. Penalty analyses were applied to determine the relative influence of perception of sensory attributes on consumer liking of the rice varieties. Across all varieties, white rice was liked more than brown rice due to the texture and colour, and Jasmine rice was preferred over Low GI and Medium Grain. Rice texture (hardness and chewiness) was the most important sensory attribute among all rice varieties and aroma was important for driving of liking between white rice varieties.

Influence of the Grouting Parameters on Microbially Induced Carbonate Precipitation for Soil Stabilization

As a novel, nature-like biomineralization process, microbially induced carbonate precipitation (MICP) has been successfully applied in soil stabilization. This study investigated the influence of biomass injected on the geotechnical performance of MICP treated sand. Grouting rate and particle sizes were also taken into account. The results showed that the injection of 1.0 or 1.2 PV biological solution achieved the most effective and uniform reinforcement of soil, depending on the grouting rate. Excessive biomass (1.5 PV biological solution) failed to promote the further improvement of the engineering performance of MICP reinforced sand. The relationship between strength and calcium carbonate content and SEM results indicated that for the small CaCO3 content, the improvement of soil strength is mainly controlled by the content of calcium carbonate rather than its distribution. When the amount of carbonate precipitation is sufficient to form bonding between soil particles, the distribution of calcium carbonate has a greater influence on mechanical properties. The strength of biocemented soil measured by layering indicated that the insufficient amount of biological solution (such as 0.5 PV biological solution) greatly weakened the reinforcement effect of soil away from the grouting port, and thus led to larger strength variability. Increasing the grouting rate of biological solution improved the uniformity of reinforcement, especially for medium grain sand. The results of this study provide a guide to facilitate the application of microorganisms in the engineering application practice of MICP.

Registration of Clearfield ‘CLM04’ southern medium grain rice

Abstract‘CLM04’ (Reg. no. CV‐155, PI 692953) is a high‐yielding, early‐maturing, and short‐stature Clearfield (BASF Corporation) medium‐grain rice (Oryza sativa L.) cultivar developed by the University of Arkansas Rice Research and Extension Center (RREC) in Stuttgart, AR, and approved for release by the University of Arkansas System Division of Agriculture Experimental Station in January 2019. It was derived from the cross ‘RU1202168'/‘Jupiter’ made at RREC in spring 2013 and advanced as F4 bulk of a single progeny row 14P54617 at the RREC in summer 2014. From 2015 to 2019, CLM04 was evaluated in 51 statewide and regional replicated trials. The Clearfield medium‐grain cultivar ‘CL272’ as well as conventional medium‐grain cultivars ‘Jupiter’ and ‘Titan’ served as checks. Grain yield of CLM04 was 9.58 Mg ha−1 compared with 9.17 Mg ha−1 for CL272, 9.97 Mg ha−1 for Jupiter, and 10.15 Mg ha−1 for Titan. CLM04 has an average height of 107 cm which is 10, 9, and 5 cm taller than Jupiter, Titan, and CL272, respectively. CLM04 reached 50% heading 5 d later than Titan at 87 d from emergence, which is similar to CL272 and Jupiter, which mature at 85 and 87 d, respectively. CLM04 is moderately resistant to leaf blast and susceptible to sheath blight, bacterial panicle blight, kernel smut, and false smut.

Registration of twoOryza sativatropicaljaponicagermplasm lines selected for panicle architecture and grain size traits

AbstractTwo rice (Oryza sativaL.) germplasm lines, SC14_166 (Reg. no. GP‐148, PI 698103) and SC14_072 (Reg. no. GP‐147, PI 698102), containing alleles for increased panicle branching, seeds per panicle, and grain length were developed by the USDA‐ARS. They are recombinant inbred lines selected from a cross of ‘Estrela’ (GSOR 301227) and NSFTV199 (GSOR 301190), both of tropicaljaponicaorigin. SC14_166 is a medium grain cultivar and contains alleles for two major genes,SPIKELET NUMBERon chromosome (chr.) 4 andFRIZZY PANICLEon chr. 7, which result in a greater number of primary branches, seeds per panicle, and panicle weight compared with the parents. SC14_072 is an extra‐long grain cultivar and contains alleles for two major genes on chr. 3,GRAIN SIZE 3andGRAIN LENGTH 3.2, resulting in greater grain length, width, thickness, and kernel weight. The germplasm lines possessPi‐ks, whereas SC_072 also hasPi‐z, both of which are major genes for resistance to rice blast disease. These germplasm lines are well adapted to growing conditions in the southern United States and will benefit long‐grain and medium‐grain breeding programs that desire to increase grain dimensions and panicle architecture traits. Because they are derived from the tropicaljaponicasubpopulation like most U.S. cultivars, they will be highly compatible for making breeding crosses and will contribute novel alleles to the gene pool.

Spatial distribution patterns of sandfish juveniles released in a sea ranch area in Maliwaliw Island, Philippines

Biophysical characteristics that affect the distribution of sandfish in the sea ranch were investigated to determine indicators for a suitable habitat for sandfish sea ranching. These include sediment grain size, organic matter (OM), chlorophyll a, pheophytin, penetrability, depth and seagrass cover. A total of 5864 hatchery-produced sandfish juveniles were released in seven batches in a 5-ha ranching site in Maliwaliw Island over a period of three years. The 5-ha ranch was divided into three zones, with Zone A (50 × 50 m) being the juvenile release site. Survey of the released sandfish was done quarterly from February 2016 until May 2017 and sediment collection done twice. A total of 750 sandfish weighing 10–600 g were recorded; 23% were <150 g, 59% were 151–350 g, 17% were 351–550 g, and 2% were >550 g. Distribution of substrate parameters between the different sea ranch zones showed no significant differences (p > 0.05). Visualized sediment grain-size data showed multiple cohorts of sandfish with varying sizes in different zones with predominantly medium and fine grains with relatively higher total OM and labile OM. Sandfish >351 g were found in deeper waters (>70 cm at low tide) with lower concentrations of labile OM and chlorophyll a, and higher pheophytin. Sandfish <350 g were found in areas with higher labile OM, higher chlorophyll a and lower pheophytin. Results of this study indicate the need for a sandfish sea ranch site with water depth >30 cm at low tide, and varying sediment particle size and composition to support the different stages of growth and development of sandfish.

Impact of diagenesis on the reservoir rock quality of the Cachiri Group tight sandstones in Cesar sub basin (Colombia): A case of study from ANH-CR-MONTECARLO 1X well

Basal sandstones of the studied interval in the Cesar Sub-basin (Colombia), have reported manifestations of hydrocarbons in the ANH CR MONTECARLO 1X well, so they have been studied as a possible unconventional reserve rock. Diagenesis plays an important role in assessing the quality of a reservoir rock, so this study presents an analysis of the diagenetic evolution in basal sandstones of the Cachiri Group in Cesar Sub-basin. Based on the petrographic and core data, diagenetic products have been determined, and how these have intervening in the quality as a possible reservoir rock. These sandstones with fine to medium grain sizes, poor to the moderate selection, are classified as arches and lithic arches. Core data porosity reveals a range between 0.06 and 2.1% and a permeability of 0.02–0.049 millidarcys (mD). These low porosity and permeability values are mainly controlled by the mechanical compaction process. Cement precipitation (carbonate, silica) also leads to a reduction in the porosity and permeability of these rocks. Other diagenetic products that can be evidenced in these sandstones are related to the metasomatism of feldspar grains by carbonate and ferrous carbonate, and dissolution of feldspar and lithic fragments.

Analysis and Interpretation of Lineaments for Evaluation of Groundwater Potential in Shendam and Environs, North Central Nigeria

This study was done to evaluate the groundwater potentials of Shendam and environs using lineaments analysis. The trends of field joints were measured during mapping and using satellite remote sensing to generate lineament. The area is underlain by crystalline basement rocks of biotite granite, medium grain granite, and syenite. Assessment was carried out to depict the possibility of groundwater occurrence in the area. LANDSAT ETM+ imagery was used, together with the geological map to investigate areas favorable for groundwater development. This was achieved by plotting the lineament trends, superimposing the lineament on the geological map, superimposing the lineament on the drainage map, furthermore by plotting density map to know the groundwater potentials of the area. Lineament was used in drawing the respective rose diagrams for each rock type. Structurally, the area is characterized by a predominant NE to SW trend which also affects or controls drainage and groundwater occurrence with major groundwater recharge areas trending NE- SW of the study area. Analyses have shown that the study area has numerous fractures whose major trends are mainly in NE-SW directions. Lineament density maps shows the cross-cutting lineaments to be relatively high in the areas around the northeastern to southwestern parts of the study area but low in the other areas. Zones of high lineament intersection density are feasible zones for groundwater prospecting.

In Vitro Comparison of Root Surface Treatment Effect between Root Scaling with Ultrasonic Inserts and Gracey Curette and Polishing with Different Cleaning Pastes

The aim of this study was the morphological evaluation of root surfaces subjected to manual (curette) and ultrasonic (conventional and diamond tips) scaling. The surface was then polished with a rubber cup and three medium-sized pastes. Ninety teeth were randomly divided into three groups of 30 and subjected to three different root instrumentation: (1) manual instrumentation with a Gracey® curette; (2) ultrasonic instrumentation with a standard steel tip (Universal Perio S-SERIES: USU, Hu-Friedy, Chicago, IL, USA) at a power equal to 50%; and (3) with a diamond tip (Punta Piezo Serie E Scaling, Hu-Friedy, Chicago, IL, USA) at a power of 20%. Each group of the instrumented teeth was then divided in three subgroups of 10 and subjected to 30 s of rubber polishing with three different polishing pastes with medium grain sizes in single-dose cups: (1) Ultrapro Tx cool mint medium®; (2) Stomyprox media®; and (3) Nupro medium orange®. Polyether root surface replicas were then taken from all 90 samples and analyzed by SEM to evaluate surface morphology after scaling and polishing procedures. All scaling techniques caused an alteration of the root surface without statistically significant difference, whereas polishing resulted in maintenance or improvement of the surface texture.

Investigating impacts of deep foundation pit dewatering on land subsidence based on CFD-DEM method

For a deep excavation in sandy cobble stratum, the loss of fine sand particles caused by dewatering generally leads to ground settlement. This paper first analyzed the rules of land subsidence caused by dewatering in the water-rich sandy cobble stratum by dewatering experiments. It is found that even after the groundwater level was restored, the land subsidence basically did not rebound, which shows that the land subsidence is consolidation settlement caused by the loss of fine particles. Then the coupled CFD-DEM numerical model was used to analyze the relationship between the fine particle loss, surface settlement and the grain size of filter media, dewatering rate. On this basis, the rules of land subsidence under the coupling effect of foundation pit dewatering and excavation were further explored by numerical calculation and field measurement. Foundation pit dewatering and excavation in the sandy cobble stratum is the key stage for land subsidence control, As the grain size of the filter media increases, the impact of dewatering on land subsidence gets stronger, therefore, the filter media grain size should be less 8 mm. This study is of great significance to the design of deep foundation pit dewatering in water-rich sandy cobble strata.

Shattering as a source of small grains in the circum-galactic medium

ABSTRACT Observed reddening in the circum-galactic medium (CGM) indicates a significant abundance of small grains, of which the origin is still to be clarified. We examine a possible path of small-grain production through shattering of pre-existing large grains in the CGM. Possible sites where shattering occurs on a reasonable time-scale are cool clumps with hydrogen number density nH ∼ 0.1 cm−3 and gas temperature Tgas ∼ 104 K, which are shown to exist through observations of Mg ii absorbers. We calculate the evolution of grain size distribution in physical conditions appropriate for cool clumps in the CGM, starting from a large-grain-dominated distribution suggested from theoretical studies. With an appropriate gas turbulence model expected from the physical condition of cold clumps (maximum eddy size and velocity of ∼100 pc and 10 km s−1, respectively), together with the above gas density and temperature and the dust-to-gas mass ratio inferred from observations (0.006), we find that small-grain production occurs on a time-scale (a few × 108 yr) comparable to the lifetime of cool clumps derived in the literature. Thus, the physical conditions of the cool clouds are favourable for small-grain production. We also confirm that the reddening becomes significant on the above time-scale. Therefore, we conclude that small-grain production by shattering is a probable cause for the observed reddening in the CGM. We also mention the effect of grain materials (or their mixtures) on the reddening at different redshifts (1 and 2).