Mean Relative Density Research Articles

Correlation of CPT measurements and relative density of LEAP-2017 and LEAP-2020 centrifuge models

Miniature cone penetration tests (CPTs) were conducted during the LEAP 2017 and LEAP 2020 centrifuge experiments to characterize and quantify the soil deposit properties. A total of 43 CPTs were obtained for deposits with varying relative densities. All experiments were performed using Ottawa F-65 Sand and used the same CPT tool model. A comprehensive study was undertaken to assess the quality and consistency of the CPT data. Outlier and regression analyses were used to develop an empirical relation to evaluate the relative density of Ottawa sand (centrifuge) deposits from measurements of the CPT tip resistance. This relation provides an estimate of the mean relative density profile, and associated standard deviation to quantify uncertainty. The relation accounts for the overburden pressure influence and the potential effects of container width (when the used container is narrow). The experimental results were found to have a good consistency with a regression R2 equal to 0.85.

An Edge-Based Approach to Partitioning and Overlapping Graph Clustering with User-Specified Density

Graph clustering has received considerable attention recently, and its applications are numerous, ranging from the detection of social communities to the clustering of computer networks. It is classified as an NP-class problem, and several algorithms have been proposed with specific objectives. There also exist various quality metrics for evaluating them. Having clusters with the required density can be beneficial because it permits the effective deployment of resources. This study proposes an approach to partitioning and overlapping clustering of undirected unweighted graphs, allowing users to specify the required density of resultant clusters. This required density is achieved by means of ‘Relative Density’. The proposed algorithm adopts an edge-based approach, commencing with the determination of the edge degree for each edge. The main clustering process is then initiated by an edge with an average degree. A cluster is expanded by considering adjacent edges that can be included while monitoring the relative density of the cluster. Eight empirical networks with diverse characteristics are used to validate the proposed algorithm for both partitioning and overlapping clustering. Their results are assessed using an appropriate metric known as the mean relative density deviation coefficient (MRDDC). This is the first work that attempts to carry out partitioning and overlapping graph clustering, which allows user-specified density.

Study of the effects of laser power and scanning speed on the microstructural morphologies and physical properties of L-PBF produced Ni52.39Ti47.61

This study examined the effect of variations in the laser power and scan speed for 52.39 at.%Ni-47.61 at.%Ti samples produced via laser powder bed fusion (L-PBF). The laser power was varied between 150W and 180 W, the scanning speeds were varied between 500 mm/s and 1000 mm/s, and other process parameters were kept constant. The resulting microstructures and physical properties of the produced samples were evaluated. In particular, the phase type and phase transformation characteristics, composition, Vickers microhardness, and microstructures were examined. It was observed that variation in the mean microhardness and relative density were not significant at a constant scan speed of 1000 mm/s, regardless of the laser power value. Samples processed at a laser power of 180W (with all other parameters kept constant) exhibited a bimodal micro- and nano structures. It was found that the samples with bimodal microstructure had a higher lattice strain, extent of B2 phase, and higher phase transformation temperatures.

Calculation Method for Traffic Load-Induced Permanent Deformation in Soils under Flexible Pavements

Rutting is one of the most common types of distress in flexible pavement structures. There are two fundamental methods of designing pavement structures: conventional empirical methods and analytical approaches. Many analytical and empirical design procedures assume that rutting is mostly of asphalt origin and can be reduced by limiting the vertical deformation or stress at the top of the subgrade, but they do not quantify the rutting depth itself. Mechanistic–empirical models to predict the permanent deformations of unbound pavement layers have been well investigated and are rather common in North America; however, they are not widely utilized in the rest of the world. To date, there is no generally accepted, widely recognized, and documented procedure for calculating permanent deformations and thus for determining the rutting depth in flexible pavement courses originating from the unbound granular layers. This paper presents a layered calculation method with which the deformation of soil layers (base, subbase, and subgrade courses) under flexible pavements due to repeated traffic load can be determined. In the first step, the cyclic strain amplitude is calculated using a nonlinear material model that is based on particle size distribution parameters (d50 and CU) and dependent on the mean normal stress, relative density, and actual strain level. In the second step, the HCA (High Cycle Accumulation) model is used to calculate the residual settlement of each sublayer as a function of the number of cycles. It is shown that the developed model is suitable for describing different types of subgrades and pavement cross-sections. It is also demonstrated with finite element calculations that the developed model describes both the elastic and plastic strains sufficiently accurately. The developed model can predict the settlement and rutting of pavement structures with sufficient accuracy based on easily available particle size distribution parameters without the need for complex laboratory and finite element tests.

Effect of coal particle density on combustion kinetics of Indian coal

ABSTRACT This work presents the combustion behavior of different mean relative densities (MRD) of Indian thermal coal. Coal of different MRD in the range of 1.25 to 2.20 was prepared using the density separation method. Essential characterization of all MRD fraction coals was done by proximate analysis, ultimate analysis, gross calorific value, BET analysis, and ash analysis. The combustion behavior of all coal samples was carried out by a thermogravimetric analyzer (TGA). Combustion characteristics parameters such as ignition temperature (TIG), peak temperature (Tmax), burnout temperature (TBT) and maximum combustion rate (DTGmax) were evaluated using TGA-DTG data. Results show that with the increase of MRD from 1.25 to 2.20, TIG and Tmax increase from 324°C and 451°C to 426°C and 462°C, respectively, while DTGmax reduces from 9.52 to 1.68 mass%/min. The kinetic analysis demonstrates that coal combustion follows the first-order reaction model and can be separated into two stages. The thermodynamic parameters signify that lighter MRD coal requires lower endothermic energy than heavier MRD coal.

The influence of cyclic preloadings on cyclic response of Zbraslav sand

This article presents a comprehensive experimental investigation on Zbraslav sand under monotonic and cyclic loading. Initially, the material response at large strains was investigated by means of undrained monotonic triaxial tests with different initial mean effective stresses and relative densities. A set of oedometric compression tests with multiple unloading–reloading cycles and different initial relative densities was as well included to evaluate the material compressibility. In addition, several undrained cyclic triaxial tests were performed and analyzed under a wide range of initial conditions. In the aforementioned tests, the undrained cyclic resistance was investigated considering different types of drained or undrained cyclic preloadings and reconsolidation stages. The experimental results suggested that drained cyclic preloadings remarkably modified the subsequent rate of pore water pressure accumulation and increased the number of cycles to reach the defined failure criterion without affecting the stress–strain response. On the other hand, undrained cyclic preloadings presented a threshold which separated positive and negative effects in the subsequent undrained cyclic resistance. A comparison of the undrained cyclic resistance variation depending on the number of drained or undrained cyclic preloadings was also included.

Pressureless flash sintering of α-SiC: Electrical characteristics and densification

The application of an electric field over a ceramic powder compact at elevated temperatures gives rise to “flash sintering”. The phenomenon occurs at a critical combination of field and temperature, which leads to a rapid increase in the electric power dissipated within the sample. This results in sample densification in far shorter timescales than those required with conventional sintering. This paper reports the first successful pressureless flash sintering of SiC with B and C sintering aids. Mean relative densities of up to 94.4% have been achieved in several minutes using an alumina tube furnace at 1500 °C. The sample temperature during flash sintering was similar to those used for conventional sintering of SiC (2100–2200 °C). The electrical response of SiC during the flash event was consistent with thermal runaway. However, the negative temperature coefficient of resistivity responsible for the runaway originated primarily from the effects of sintering, in contrast to the case with oxide ceramics. The rapid sintering was attributed to the rapid heating and the formation of a liquid phase. The densest specimen had a grain size of 5.9 µm ± 0.5 µm and a Vickers hardness (HV5) of 24.7 GPa ± 0.5 GPa. These values were similar to those of conventionally sintered specimens of the same powder but the production time of the flash sintered samples was reduced by more than 6 h and with a furnace temperature lower by 700 °C.

Attempts to use breeding approaches in Aedes aegypti to create lines with distinct and stable relative Wolbachia densities

Wolbachia is an insect endosymbiont being used for biological control in the mosquito Aedes aegypti because it causes cytoplasmic incompatibility (CI) and limits viral replication of dengue, chikungunya, and Zika viruses. While the genetic mechanism of pathogen blocking (PB) is not fully understood, the strength of both CI and PB are positively correlated with Wolbachia densities in the host. Wolbachia densities are determined by a combination of Wolbachia strain and insect genotype, as well as interactions with the environment. We employed both artificial selection and inbreeding with the goal of creating lines of Ae. aegypti with heritable and distinct Wolbachia densities so that we might better dissect the mechanism underlying PB. We were unable to shift the mean relative Wolbachia density in Ae. aegypti lines by either strategy, with relative densities instead tending to cycle over a narrow range. In lieu of this, we used Wolbachia densities in mosquito legs as predictors of relative densities in the remaining individual’s carcass. Because we worked with outbred mosquitoes, our findings indicate either a lack of genetic variation in the mosquito for controlling relative density, natural selection against extreme densities, or a predominance of environmental factors affecting densities. Our study reveals that there are moderating forces acting on relative Wolbachia densities that may help to stabilize density phenotypes post field release. We also show a means to accurately bin vector carcasses into high and low categories for non-DNA omics-based studies of Wolbachia-mediated traits.

Harvest impacts to stand development and soil properties across soil textures: 25-year response of the aspen Lake States LTSP installations

In addition to long-standing concerns about sustaining forest productivity, maintaining forest ecosystems under changing conditions and emerging threats has become increasingly important when planning forest management. With the aim of understanding effects of management on both productivity and recovery, we quantified the 25-year impact of varying degrees of organic matter (OM) removal and soil compaction on above-ground biomass, soil carbon and nutrients, soil bulk density, and stand development in aspen-dominated forests in the upper Lake States region of the US. Treatment impacts were assessed at three different sites with comparable overstory composition, but with varying soil texture, site quality, and climate. Across all sites, soil C and N generally decreased with increasing OM removal, and bulk density increased with increasing compaction; 25-year observations indicate recovery of bulk density at the surface (0–10 cm) but not at deeper portions of the soil profile. At the most productive site (loamy soils) with favorable initial soil porosity, severe compaction decreased mean aboveground biomass (-46%), particularly of trees (-73%). Biomass at 25 years did not differ among organic matter removal treatments (e.g. stem-only harvest), but a greater increase in soil C occurred with stem-only harvest relative to whole-tree harvest plus forest floor removal. In contrast, at a less productive site with sandy soils poorly buffered to nutrient and C removals, whole-tree harvest reduced biomass by 25% (tree biomass declined 35%) relative to stem-only harvest while compaction treatments did not differ in effects on biomass production, soil C or soil N. On clay soils, compaction treatments did not significantly impact biomass production, but whole-tree harvest plus forest floor removal reduced tree biomass by 47% relative to whole-tree harvest alone. Assessment of mean relative density indicates canopy closure has not yet occurred at the least productive site (clay soils) or the more severely disturbed stands at the intermediate site (sandy soils), suggesting the possibility for treatment impacts not yet discernible to become more pronounced as stands develop and nutrient uptake continues in the future. Our results align with concepts of soil quality and texture-specific limitations to growth, underlying a need to understand key soil limitations when considering forest management impacts to aboveground structure and productivity.

Use of powder bath sintering for the fabrication of hard ceramic tools

ABSTRACT This article investigates the effect of ceramic powder bath heat-treatment on the sintering of α-alumina (α-Al2O3) for potential ceramic tool application. Three different ceramic sintering mediums were used i.e., (i) Pure alumina powder bath, (ii) Pure graphite powder bath, and (iii) Alumina Graphite Powder Bath (AGPB). The hardness and microstructural analysis were carried out using Vickers hardness, Field Emission Scanning Electron Microscopy (FESEM), and Scanning Electron Microscopy (SEM). The experimental results revealed that the novel Alumina Graphite Powder Bath (AGPB) sintering mechanism proposed in this research provided better hardness and microstructure as compared to the rest. The heating mechanism of alumina and graphite powder mixture was compared with published Thermogravimetric analysis (TGA) results. The Alumina Graphite Powder Bath (AGPB) sintering method improved the mean hardness and relative density by 23% and 13%, respectively. Further, an orderly crystalline corundum microstructure with closed porosity was revealed from Scanning Electron Microscopy (SEM) micrographs. The conversion of convection-radiation to conduction mode of heat transfer in Alumina Graphite Powder Bath (AGPB) sintering technique was the reason behind this property enhancement.

The PHYTOSOCIOLOGY OF WEEDS IN AGRICULTURE FARM, THE UNIVERSITY OF AGRICULTURE PESHAWAR- PAKISTAN

Weeds interference with crops and native useful plants, causing negative impacts on crop production and biodiversity. Weeds being more adaptable to changing climate establish easily into new areas becoming invasive over the native vegetation. To investigate further the adaptability of invasive weeds and their status among the native plant community a field survey was carried out from July – September, 2017 at New Developmental Farm (NDF), Malakandher, The University of Agriculture, Peshawar to record weeds species composition. Data was sampled from three different sites i.e. field crop area, non-field and orchards with a quadrate randomly thrown 50 times at different locations. A total of 39 weeds species from 16 families (14 dicot and two monocot) and 36 genera were identified. Dicots were dominant as compared to monocot. The major monocot family poaceae contributed 10 species while in dicots Asteraceae took the lead with 6 species, followed by Euphorbiaceae with 3 species. The rest of the plant families include Aizoaceae, Amaranthaceae, Convolvulaceae, Cucurbitaceae, Cyperaceae, Euphorbiaceae, Malvaceae, Nyctaginaceae, Oxidillaceae and Plantaginaceae. Among the weed species 27 were annual and the rest (12) were perennials. Annuals were reported from all the three sites, while perennials were found in non-field area i.e. irrigation canals, field ridges, orchards and undisturbed waste areas. Data regarding absolute and relative density, frequency, relative frequency and importance valve of weeds of the area were recorded by quadrate method. Cynodon dactylon had the highest relative density (27.21%), followed by Digiteria sanguinalis (14.87), Cyperus rotundus (12.96) and Euphorbia prostrata (5.12) relative density, respectively. Parthenium hysterophorus L. an invasive alien weed was recorded in almost all the localities with a weed density of 2.6 m-2 in non-field area especially, followed by 0.85 m-2 in field crop and 0.8 m-2 in orchards and with a mean density of 1.42 m-2 and a relative density % of 1.52 across all locations. Similarly another invasive weed Broussonetia papyrifera was recorded in non-field area only with lowest mean relative density of 0.07%. Mean distribution data showed highest relative frequency for C. dactylon (13.66 %) followed by D. sangunalis (10.22), C. rotundus (7.86) and S. halepense (7.23), respectively. Alhaji maurorum, Eclipta alba, Cucumis callosus, B. papyrifera, Withania somnifera and Boerhavia diffusa took the smallest relative frequency of 0.38 % at most of the locations studied thereby indicating them as insignificant among the weed flora of the study area. Importance value data revealed that C. dactylon, D. sangunalis, C. rotundus and S. halepense having IV % of 34.03, 19.99, 16.89 and 10.17, respectively. Looking at the overall distribution of weeds flora in NDF Malakandher during the summer season C. dactylon is distributed on road sides, field ridges, irrigation channels, agricultural fields, orchards and waste lands, while P. hysterophorus being an invasive weed showed increasing trend compared to its earlier status evident from previous study.

Evaluation of a high-throughput in vitro endothelial cell migration assay for the assessment of nicotine and tobacco delivery products

Endothelial cell migration is a critical process in the maintenance of healthy blood vessels. Impaired endothelial migration is reportedly associated with the development of cardiovascular diseases. Here, we report on the development of a 96-well in vitro endothelial migration assay for the purpose of comparative toxicological assessment of a novel THP relative to cigarette smoke, to be able to rapidly inform regulatory decision making.Uniform scratches were induced in confluent human umbilical vein endothelial cells using the 96-pin wound maker and exposed to 3R4F cigarette or THP aqueous extracts (AqE). Endothelial migration was recorded over 24 h, and the rate of wound closure calculated using mean relative wound density rather than migration rate as previously reported. This self-normalising parameter accounts for starting wound size, by comparing the density of the scratch to the outer region at each time-point. Furthermore, wound width acceptance criteria was defined to further increase the sensitivity of the assay.3R4F and THP AqE samples were tested at comparable nicotine concentrations. 3R4F showed significant cytotoxicity and inhibition of wound healing whereas THP AqE did not show any response in either endpoint. This 96-well endothelial migration assay was suitably sensitive to distinguish combustible cigarette and THP test articles.

Fast recovery of house infestation with Triatoma brasiliensis after residual insecticide spraying in a semiarid region of Northeastern Brazil.

The northeastern semiarid region stands out in the Brazilian context regarding the eco-epidemiology of Chagas disease, in which Triatoma brasiliensis is the main vector of Trypanosoma cruzi. Persistent house invasion threatens the relative levels of progress achieved over previous decades. We conducted an intervention trial with a five-year follow-up to assess the impacts of residual spraying with pyrethroid insecticides on house infestation with T. brasiliensis in 18 rural villages (242 houses) located in the Tauá, Ceará. House infestations were assessed by systematic manual searches for triatomines in every domestic and peridomestic habitat on five occasions. Triatomines were collected in peridomestic (57.5%), sylvatic (35.8%), and intradomiciliary (6.7%) habitats. The most important ecotopes of T. brasiliensis were containing roofing tiles, bricks or rocks (23.4% ± 9.1). Residual insecticide spraying substantially reduced baseline house infestation rates from 27.9% to 5.9% by 6 months post first spraying (MPS). The decline was substantially greater in intradomiciles (11.2% to 0.8%) than in peridomiciles (16.7% to 5%). The mean relative density of triatomines recovered its preintervention values at 14 MPS in intradomiciles, and in the main peridomestic ecotopes. The house infestation levels recorded at 14 MPS persisted thereafter despite all reinfested houses were selectively sprayed on every occasion. Overall average bug infection rates with T. cruzi in the five occasions were in intradomiciles (11.1%), peridomiciles (4.7%) and wild habitats (3.3%). In peridomicile T. cruzi infection rates decreased significantly at all stages after chemical intervention. In intradomicile, the only significant difference occurred at 20 MPS (7.7% to 30.8%). The vectorial capacity of T. brasiliensis, combined with its invasive potential from sylvatic sources and the limited effectiveness of chemical control in the harsh caatinga landscape, pose serious obstacles to the definite elimination of domestic transmission risks. Systematic vector surveillance supported by community participation and locally adapted environmental management measures are needed to reduce the risks of establishment of domestic transmission with T. cruzi in this region.

Diversity of plant parasitic nematodes associated with rhizosphere of maize from different areas of district Rajouri, Jammu and Kashmir, India

Diversity of plant parasitic nematodes in the rhizosphere of maize (Zea mays) from some areas of District Rajouri, Jammu and Kashmir was studied. A total of ten plant parasitic nematode species were found to be associated with the rhizosphere of maize plants in these areas. The nematode species were Pratylenchus zeae, P. brachyurus, Helicotylenchus dihystera, Longidorus brevicaudatus, L. elongatus, Xiphinema diversicadatum, X. elongatum, Tylenchorhynchus spp. Ditylenchus spp. and Criconemoides spp. The most dominant and frequently occurring species was found to be P. zeae, with absolute frequency of 86.66% followed by P. brachyurus (80%), H. dihystera, (76.66%) and L. brevicaudatus (73.33). Contrarily, the least frequent was Criconemoides spp. (36.66%) followed by Tylenchorhynchus spp. and Ditylenchus spp. with absolute frequencies of 53.33% and 60%. Similar trend was observed in case of relative frequencies. In case of P. zeae, mean density of 56 and relative density of 16.05% was observed followed by P. brachyurus and H. dihystera with mean densities and relative densities of 50.33, 14.43% and 49, 14.04% respectively. On the other hand, Criconemoides spp. and Tylenchorhynchus spp. showed mean densities of 6.33 and 23.33 and absolute densities of 1.81% and 6.68% respectively. P. zeae exhibited high prominence value of 57.85 followed by P. brachyurus (49.96). The least prominence value was found in Criconemoides spp. (4.05) followed by Tylenchorhynchus spp. with prominence value of 18.30.

Distribution of Helminth parasites and seasonal rate of infection in Clarias batrachus (Jerdon, 1849) fishes of Savitri River from Konkan region, Maharashtra, India

The present study was undertaken to determine the incidence of helminth parasites in fishes in Savitri, river in Konkan region of Maharashtra. Fish and their parasites were collected during different seasons from various sites like Chiplun, Sangameshwar, Dapoli, Khed, Mandangad etc. For three year period and processed. Fish species namely Clarias batrachus from these water bodies. The parasitological examination of fishes was carried as per methodology. The parasites were processed and identified with the help of key. The prevalence mean intensity and relative density of Helminth parasites were calculated in accordance. The study of Cestode parasite population of river water fishes of different regions of Ratnagiri district has been unde rtaken to investigate the phonological and innate factors such as season, habit and habitat. The investigation of parasitogenesis can provide data for the prediction of integrated methods to achieve the regulation of number of parasites from various genera, quantitative data are vital.

Impact of acuros XB algorithm in deep-inspiration breath-hold (DIBH) respiratory techniques used for the treatment of left breast cancer.

To investigate the impact of Acuros XB (AXB) algorithm in the deep-inspiration breath-hold (DIBH) technique used for treatment of left sided breast cancer. AXB may estimate better lung toxicities and treatment outcome in DIBH. Treatment plans were computed using the field-in-field technique for a 6 MV beam in two respiratory phases - free breathing (FB) and DIBH. The AXB-calculations were performed under identical beam setup and the same numbers of monitor units as used for AAA-calculation. Mean Hounsfield units (HU), mass density (g/cc) and relative electron density were -782.1 ± 24.8 and -883.5 ± 24.9; 0.196 ± 0.025 and 0.083 ± 0.032; 0.218 ± 0.025 and 0.117 ± 0.025 for the lung in the FB and DIBH respiratory phase, respectively. For a similar target coverage (p > 0.05) in the DIBH respiratory phase between the AXB and AAA algorithm, there was a slight increase in organ at risk (OAR) dose for AXB in comparison to AAA, except for mean dose to the ipsilateral lung. AAA predicts higher mean dose to the ipsilateral lung and lesser V20Gy for the ipsilateral and common lung in comparison to AXB. The differences in mean dose to the ipsilateral lung were 0.87 ± 2.66 % (p > 0.05) in FB, and 1.01 ± 1.07% (p < 0.05) in DIBH, in V20Gy the differences were 1.76 ± 0.83% and 1.71 ± 0.82% in FB (p < 0.05), 3.34 ± 1.15 % and 3.24 ± 1.17 % in DIBH (p < 0.05), for the ipsilateral and common lung, respectively. For a similar target volume coverage, there were important differences between the AXB and AAA algorithm for low-density inhomogeneity medium present in the DIBH respiratory phase for left sided breast cancer patients. DIBH treatment in conjunction with AXB may result in better estimation of lung toxicities and treatment outcome.

Fish assemblages associated with artificial reefs assessed using multiple gear types in the northwest Gulf of Mexico

Quantitative surveys of fishes associated with artificial reefs in the northwest Gulf of Mexico were conducted over a 4-yr period (2014–2017). Artificial reefs surveyed were comprised of three types: concrete structures, rig jackets, and decommissioned ships. All reefs were surveyed using vertical long line (VLL), fish traps, and Adaptive Resolution Imaging Sonar (ARIS 1800). Mean fish abundance did not significantly differ using VLL [1.7 ind set –1 (SD 2.2)] among the three reef types. However, relative abundance among all fishes collected was significantly highest on rig reefs using traps [6.2 ind soak–1 (SD 3.8)], while results from sonar surveys indicated that the mean relative fish density was highest on concrete reefs [15.3 fish frame–1 (SD 26.8)]. Red snapper (n = 792), followed by gray triggerfish (n = 130), pigfish (n = 70), tomtate (n = 69), and hardhead catfish (n = 57) were the most numerically abundant species using VLL and traps; red snapper comprised 90.7% of total catch using VLL and 43.9% using traps. Mean Brillouin's diversity (HB) was highest on ships using VLL [0.41 (SD 0.14)] and highest on rigs using traps [0.87 (SD 0.58)] compared to the lowest diversity found on concrete [VLL 0.07 (SD 0.11); traps 0.36 (SD 0.32)]. Findings from this study can be used to inform the planning of future artificial reefs and their effect on the assemblages of reef-associated fishes. Additionally, these results highlight the value of using multiple gear types to survey reef fish assemblages associated with artificial reefs.

Insect pests of black gram in rice based farming

This study was conducted during August to November in 2016 and 2017 to record the insect pests that attack black gram grown in a sequential farming at rice nursery located in the village Dehar Kuriha under Hajo revenue circle of Assam. Thirteen insect species under Lepidoptera, Coleoptera, Orthoptera and Hemiptera were identified, with more than 50% belonging to the Hemiptera. Incidence and damage of Omiodes indicata, Maruca testulalis and Apion clavipes were found high. The highest mean density (227.2/plot and 231.11/plot) and relative density (21.8% and 22.2%) was found in Apion clavipes. Most of the insect pests made their appearance in the 39th standard week of the crop growth.

Sand–concrete interface response: The role of surface texture and confinement conditions

Sand–concrete interface direct shear tests were used to investigate the effects of surface roughness, surface waviness, mean sand diameter and relative density on interface strength and behavior under different confinement conditions. Extreme concrete surface textures, including smooth, rough and rough–wavy textures, were reproduced. Surface plowing was assessed via image analysis, laser scanning and extended multifocal micrographs. The experimental results showed that smooth concrete surfaces exhibited high values of interfacial–to–internal friction angle ratios, ranging 88–90%, due to the angular shape of sand particles. The rough concrete surfaces generated higher interface strength than smooth concrete surfaces; however, the interface strength was still inferior to the surrounding sand strength. Surface plowing, which identified a mixed shear plane at the sand–concrete interface, was developed as particles were detached from the surface, thus inhibiting the interface friction angle from reaching the sand friction angle. Higher sand–concrete interface strength was achieved as surface waviness increased, and interface friction angles greater than the surrounding sand friction angle were reached. Under a constant normal stiffness condition, significantly high interface strength is achieved due to the increase of the current normal stress, which was directly influenced by the initial normal stress, stiffness, surface roughness, mean sand diameter and relative density; surface waviness did not have a marked effect on the normal stress variation. Based on these results, multiple regressions were proposed to estimate the sand–concrete interface strength by the interfacial–to–internal friction angle ratio and the effect of the constant normal stiffness condition.

Highly dense Ca5(PO4)2SiO4 bioceramics with ultrafine microstructure prepared by pressureless sintering

Si-containing ceramics are regarded as promising materials for bone regeneration. And microstructure is a key factor for both mechanical and biological properties of bioceramics. In the present work, nanocrystalline Ca5(PO4)2SiO4 (CPS) powders were prepared by ultrasound-assisted precipitation method. The sintering behavior of CPS ceramics was investigated by pressureless sintering. Results showed that the synthesized CPS powders with an apparent crystallite size of 84 nm exhibited an excellent sintering capability. Grain growth of CPS ceramics could be effectively suppressed via TSS method, and the mean grain size, relative density and Vickers hardness of CPS ceramics obtained under the optimized conditions were 0.42 μm, 98.40% and 5.22 GPa, respectively. Therefore, TSS process provides a facile method to fabricate highly dense CPS bioceramics with ultrafine microstructure, which are expected to be promising materials with improved mechanical and biological properties for bone regeneration applications.