Bulk Density Research Articles

The Flammability and Thermal Stability of Filling Epoxy Foam Plastics for Construction Purposes.

An effective type of polymer heat-insulating material (foams) based on reactive oligomers is casting epoxy foams with high technological and operational parameters. However, polyepoxide foams are highly flammable, which significantly restrains their application in the construction industry. The aim of this work was to develop effective methods for reducing the flammability of filling epoxy foams. In order to achieve the objective, the following objectives were addressed: determining the influence of the chemical nature and content of additive and reactive bromine- and phosphorus-containing compounds on the thermal stability, flammability and operational properties of filling epoxy foams, and the development of polyepoxy foams of reduced flammability with high-quality physical and mechanical characteristics. When estimating the flammability of epoxy foams, we used both state-approved methods and the methods described in scientific and technical literature. The thermal properties of epoxy foams were studied with the help of multimodular thermoanalytical complex DuPont-9900. The data on the influence of the apparent density of foams and oxygen concentration in the oxidant flow on the flame propagation speed on the horizontal surface of polyepoxy foams are presented. It was revealed that the chemical nature of amine hardeners does not affect the thermal stability and flammability of epoxy foams. It was established that phosphate plasticizers are ineffective flame retardants of foamed epoxy resin, and the chemical structure of additive organobromic flame retardants insignificantly affects their efficiency. It was shown that microencapsulated flame retardants are inferior in flame retardant efficiency to additive flame retardants. It was found that effective flame retardants for casting polyepoxy foams are phosphorus-containing oligoether methacrylate and epoxidized waste from the production of tetrabromodiphenylpropane. The results of this research will form the basis for the production of an experimental industrial batch of samples of pouring epoxy foams of reduced flammability.

Estimating the snow density using collocated Parsivel and Micro-Rain Radar measurements: a preliminary study from ICE-POP 2017/2018

Abstract. A new method is developed to derive the bulk density and bulk water fraction of a population of particles from collocated measurements from the Micro-Rain Radar (MRR) and Particle Size and Velocity disdrometer (Parsivel). A rigorous particle-scattering simulation, namely the T-matrix method, is applied to Parsivel's particle size distribution data to calculate the reflectivity (ZHH). The possible combinations of the particle's ice, air, and water are derived to compare them with the MRR-measured ZHH. The combination of the minimum water fraction and maximum ice fraction subsequently determines the bulk density (ρbulk). The proposed method is applied to the data collected from the International Collaborative Experiments for Pyeongchang 2018 Olympic and Paralympic winter games (ICE-POP 2018) projects and its pre-campaign. The estimated ρbulk was examined independently by a comparison of the liquid-equivalent snowfall rate (SR) of collocated Pluvio devices. The bias values are adequately low (SR: −0.25–0.06 mm h−1). The retrieved bulk density also shows good consistency with collocated Precipitation Imaging Package (PIP) retrievals. The results indicate the capability of the proposed algorithm to derive reliable ρbulk, leveraging the compact and easily deployable designs of MRR and Parsivel. The derived bulk density of the two warm–low cases (28 February and 7 March 2018) shares a similar transition as the systems were decaying. The higher bulk density and bulk water fraction were found in the coastal sites (BKC and GWU have a median value of ρbulk and are 0.05 to 0.12 g cm−3), typically accompanied by higher liquid-water constituents (mean values of the top 5 % bulk water fraction are 0.07 to 0.45) than the inland sites (YPO and MHS have a median value of ρbulk and are 0.06 to 0.10, and mean values of the top 5 % bulk water fraction are 0.001 to 0.008) during such synoptic conditions.

Study on recrystallization process of nitroguanidine by directly adding cold water to control temperature

Abstract Nitroguanidine (NGu), as a kind of high-energy material, is widely used as explosive propellant and energy component of explosives and smokeless powder. However, NGu crystals prepared by crystallization process are hollow and long needles, and their bulk density and bombing performance are greatly limited due to the high energy density at the tip, large porosity, and poor fluidity. Surprisingly, the particle size and morphology of NGu can effectively be improved by the recrystallization process. In this article, the recrystallization process by directly adding cold water to control temperature is first proposed, aiming to improve the morphological characteristics and reduce the particle size of NGu. Through single factor experimental research, the influences of various operating parameters on the morphology and particle size of NGu during recrystallization process were studied in detail. The results showed that the smallest average particle size of NGu was 19.8 μm when the crude NGu concentration, cold water temperature, volume ratio of boiling to cold water, stirring speed, and polyvinyl alcohol concentration were 5 g/100 mL, 0°C, 1:1, 800 rpm, and 0.35 g/100 mL, respectively. Correspondingly, the morphology of NGu was short rod, which was helpful to improve the bulk density. This novel recrystallization process has great potential to improve the NGu morphological characteristics, providing a new idea for the preparation of military NGu with small particle size and high bulk density.

The influence of the granulometric composition of powders of steels and precision alloys and their melting modes by LPBF ON porosity

The results of the experimental study of powder materials of various brands and classes (stainless steel, precision soft and hard magnetic alloys) are presented, the influence of their parameters (particles, fracture, fluidity, bulk density) on the properties of finite additive samples is evaluated. The impact of melting parameters on the porosity of additive samples has been studied.

Comparative Analysis of the Strength of Concretes Made from Different Aggregates

The paper aimed to explore the replacement of river sand in concrete with iron fillings and sawdust at various percentages (10%, 20%, and 30%). The study used a 1:2:4 mix design and a water-cement ratio of 0.5. Wooden square cubes of dimensions 100 x 100 x 100 mm were employed, resulting in 42 concrete cubes. Tests were conducted to assess particle size distribution, specific gravity, bulk density, aggregate impact value, aggregate abrasion value, and compressive strength at 7th and 28th days of curing. Notably, after 7 days, compressive strength results showed that concrete with a 10% iron fillings replacement (18.5 N/mm²) had a higher average strength than concrete with 100% river sand (17.6 N/mm²). However, as the percentage of iron fillings increased to 20% (9.8 N/mm²) and 30% (7.1N/mm²), the compressive strength decreased. On the other hand, concrete with sawdust replacements at 10% (3.7 N/mm²), 20% (1.4 N/mm²), and 30% (0.5 N/mm²) exhibited significantly lower load-bearing capacity. These trends persisted at the 28th day, with the compressive strength decreasing with increasing percentages of iron fillings (10%: 20.3 N/mm², 20%: 11.2 N/mm², 30%: 11.6 N/mm²) and sawdust (10%: 3.4 N/mm², 20%: 2.3 N/mm², 30%: 1.4 N/mm²). The findings suggest that a low percentage of iron fillings can be used in combination with river sand to maintain load-bearing capacity, but sawdust or wood particles should be avoided as they adversely affect compressive strength. This research contributes valuable insights into the use of these materials in concrete mixtures.

Optimization, Kinetic and Thermodynamic Study of Rhodamine B Removal by Zinc Chloride-activated Arachis hypogaea (Groundnut Husk) biochar

Adsorption of dye from industrial effluent before discharge into the environment has become a major challenge to the food, pharmaceutical, textile, photographic and cosmetic industries. This has led scientists to the search for suitable green solutions. Carbonized and zinc chloride activated Arachis hypogaea (groundnut husk) in a 1:1 ratio was used as an adsorbent for the removal of Rhodamine B from aqueous solution. The adsorbent was characterized by ash content, bulk density, moisture content, pH, Iodine number, surface area and functional group analyses. Key parameters such as initial pH, initial concentration of Rhodamine B dye, temperature and contact time were investigated. The equilibrium data obtained were correlated with Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. It was found that both the Freundlich and Langmuir isotherms fit well to the data. The Langmuir isotherm model best describes the uptake of Rhodamine B onto zinc chloride activated groundnut husk biochar with R2 > 0.997. Maximum Rhodamine B. dye removal was observed at a pH of 11.0, with an adsorbent dosage of 1.0 g, a contact time of 125 min, an initial dye concentration of 20 mg/L and a temperature at 315 K. The efficiency of zinc chloride activated groundnut husk biochar for Rhodamine B removal was 99.55% for dilute solutions at 50 g/L. The Fourier Transform Infrared (FTIR) spectra recorded before and after activation showed the numbers of functional groups available for Rhodamine B. molecules to bind onto in the studied adsorbent. The kinetic data were best described by the pseudo-first-order and pseudo second-order models, while the thermodynamic studies indicated a spontaneous and endothermic nature in the adsorption of Rhodamine B by the zinc chloride modified groundnut husk. This research clearly details an innovative approach to utilizing carbonized and zinc chloride-activated Arachis hypogaea (groundnut husk) as an eco-friendly adsorbent for the removal of Rhodamine B from industrial effluents.

Exploring the Soil Structure Analysis of a Subtropical Watershed by Introducing a Blanket Physico‐Hydraulic Health Index

ABSTRACTMultiple disturbed and undisturbed soil samples were collected to assess the soil structure health in support of water use and management in a subtropical watershed, which is composed of shallow Entisols, near to Canguçu, RS state—Brazil. Various physico‐hydraulic properties related to soil structure, such as bulk density, total, micro and macroporosity, saturated hydraulic conductivity, organic carbon, soil water retention curve (SWRC), and the ranges of plant available water (PAWC) and drainable porosity (DP) were measured to be analyzed. The hydraulic‐energy indices of soil aeration and water retention were determined by integrating the areas under SWRC. Combining these properties with the contents of sand and clay, a unique blanket soil physico‐hydraulic health index (BSPHI) was formulated and applied to investigate the impact of land use and management on the soils of the Ellert Creek Watershed (ECW), thereby supporting soil physical health analysis and, consequently, the analysis of water and human health. The favorable outcomes found in the ECW soils under annual crops indicated good root aeration in the surface layer due to the balance between DP and PAWC. The BSPHI results showed that only about 19% of the areas exhibited unhealthy physical health. The soil structure in pasture areas of ECW was not significantly impacted by the extensive cattle grazing, whereas lands under native forest served as a control for the natural soil quality status. The BSPHI successfully captured small changes in soil structure, regardless of land use and management, highlighting its potential as a promising tool for evaluating soil health by assessing the soil physical quality.

Concretes meeting the requirements of sustainable construction

The article concerns the production of lightweight geopolymer concretes based on raw materials from alkali-activated waste, which is consistent with the doctrine of sustainable construction. Fly ash, which is the main component of these geopolymer composites, constitutes energy waste and causes lower emissions of greenhouse gases and other pollutants than traditional cement. The article presents the optimisation of the geopolymer concrete recipe with different dosages of fly ash (200, 300, 400, 500, 600 and 700 kg/m3) and two recipes, the first of which is based on the use of fly ash aggregate, the largest fraction of which was subjected to surface impregnation, and the second one is based on the use of aggregate without any impregnation. Both recipes use an alkaline solution for alkaline activation with a concentration of 6 mol/dm3. Compressive strength tests and apparent density were carried out on the samples. The adequacy of the use of surface impregnation has been demonstrated in the case of low fly ash content (<500 kg/m3), and the optimal recipe based on fly ash in the amount of 600 kg/m3 was indicated.

Биофизични коефициенти на евапотранспирацията на главеста целина (Apium graveolens) за района на Пловдив

A three-year field experiment was conducted with celery under irrigated conditions in the Plovdiv region 42° 08‘ 06“ N024° 44‘ 43“ E and 160 m above sea level. The purpose of the development is to establish the biophysical coefficients (Z, R and Ks) of the evapotranspiration of the crop and to recommend the most suitable ones for managing the irrigation regime. The experiment spanned three distinct years, each characterized by varying climatic factors. Throughout all three years, vegetation precipitation was insufficient and unevenly distributed. Post statistical analysis, they were defined as wet, medium and dry. The soil is an alluvial meadow with a bulk density of 1.33 g/cm3 for the 0-0.4m layer where soil moisture was monitored. Real evapotranspiration data of celery, obtained via the weight-thermostat method with regular soil sampling, were used. Three phases of celery development are distinguished, the first being from the interception of seedlings to the beginning of the formation of the root crop, the second - covering the beginning of growth of the root crop and the third phase - from intensive growth to harvest. The Z-factor values by phase were 0.14, 0.21, and 0.24 for R – 0.24, 0.4 and 0.6, and for Kc – 0.65, 1.01 and 1.51.

Smoldering Ignition and Transition to Flaming Combustion of Pine Needle Fuel Beds: Effects of Bulk Density and Heat Supply

The smoldering of pine needle fuel beds (PNBs) has been a common subject of research because of its importance in initiating the rekindling of forest floor fires. Experimental studies of the coupling effects of the bulk density and external heat supply on smoldering in PNBs have been scarce up to now. In this study, laboratory smoldering experiments were conducted to study the coupling effects of bulk density (30–55 kg m−3) and heat supply (ignition-off temperature Toff = 190 °C and 230 °C). Different ignition modes were observed under the same conditions, including non- ignition (NI), flaming ignition (FI), and the smoldering-to-flaming (StF) transition. The results in this study showed that the bulk density had distinct effects on different ignition modes: the increase in the bulk density facilitated the StF transition but impeded the FI. The coupling effects between the bulk density and heat supply became more intricate, especially at lower bulk densities and at a reduced heat supply. Additionally, a simple energy balance equation was established to explain the coupling effects of bulk density and heat supply on ignition behavior. The critical mass loss rate (MLR) for the StF transition ranged from 0.01 g s−1 to 0.03 g s−1, while the critical MLR for FI was 0.035 g s−1. The modified combustion efficiency (MCE) index for the StF transition decreased from approximately 79.6% to 70.1% as the density increased from 30 kg m−3 to 55 kg m−3. In contrast, the MCE for FI was approximately 90% across all the bulk densities. The StF transition delay time increased from 50 s at 30 kg m−3 to 1296 s at 55 kg m−3 when Toff = 230 °C. Further reduction in heat supply led to an increase in the delay time for the StF transition by diminishing the intensity of smoldering combustion. This work advances the fundamental understanding of how heat supply and bulk density impact smoldering ignition modes, ultimately aiding in the development of wildfire prevention strategies.

Research on Deterioration Behavior of Magnesium Oxychloride Cement Under High Humidity and High Temperature.

To clarify the deterioration behavior of magnesium oxychloride cement (MOC) under conditions of high humidity and high temperature, we first placed MOC slurry samples in a simulated environment with a relative humidity of 97 ± 1% and a temperature of 38 ± 2 °C; then, we observed the changes in the macroscopic and microscopic morphology, water erosion depth, bulk density, phase composition, and mechanical properties of the samples. The results show that, over time, under the promotion of high temperature, water molecules infiltrate the MOC samples. This results in the appearance of cracks on the macroscopic surface of the MOC samples due to the volume expansion caused by the hydrolysis of P5 (5Mg(OH)2·MgCl2·8H2O) and the hydration of unreacted active MgO in the samples. The microscopic morphology of the samples changes from needle/gel-like, to flake-like, and finally leaf-like. Simultaneously, the major phase composition turns into Mg(OH)2. Since the structure of the samples becomes looser and the content of the main strength phase decreases, the overall compressive strength and flexural strength are both reduced. The compressive strength of the MOC slurry samples (0 day) is 93.2 Mpa, and the flexural strength is 16.4 MPa. However, after 18 days of treatment, water molecules reach the center of the MOC samples, and the MOC samples completely lose their integrity. As a result, their compressive and flexural strengths cannot be obtained.

A case study of crushed stone for road construction application: amphibolite and basalt varieties from Croatia

Crushed stone is one of the most exploited and important mineral raw material. Emphasis is given to determination of mineralogical and petrographic properties, of two genetically different rocks of silicate composition, commonly used as crushed stone for road constructions, as their physical properties depend on them. First is amphibolite from Vetovo, and second is basalt from Vratnik locality, both sourced from Croatia. Tests conducted according to European and Croatian norms evaluated the real and apparent density, open and total porosity, and water absorption of stones. The relationship between mineralogical and physical properties led to the following conclusions: the open porosity values of amphibolite samples are low, which is a consequence of the medium to high degree of metamorphism, (plagioclase and hornblenda), sosiritization, and undisturbed rock features. The total water saturation was achieved in a brief time, confirming this statement. The basalts have different porosity and water absorption values, which are consequences of differences their textural-structural properties (glassy, intersertal or intergranular groundmass), amount of amygdules, presence or absence of chlorite/volcanic glass. Furthermore, the percentage of plagioclase in the modal composition differs, and the plagioclase itself has been altered, and the amount of clay, sericite and calcite vary in two different varieties of basalt. Compared to amphibolites, basalts have notably higher water absorption values as well. Accordingly, the studied amphibolite has water absorption less than 0.5% and is suitable for use in a road construction application for wearing course in the asphalt pavement, and studied basalt is not.

Effect of layered fertilizer strategies on rapeseed (Brassica napus L.) productivity and soil macropore characteristics under mechanical direct-sowing

Layered fertilization parameters affects crop root system configuration and growth distribution, which in turn affects soil pore properties and aggregate structure. Therefore, understanding the spatial distribution of the root system and soil pore space is helpful in choosing a reasonable fertilization ratio in production practice, which ensures high and stable crop yields and at the same time improves fertilizer utilization and soil health. Albeit the impact of layered fertilization ratio at varied rates on soil pore characteristics in the soil profile at a microscale level remains limited. This study quantifies the impacts of layered fertilization ratio under on rapeseed root distribution and soil pore characteristics using the root analysis system and X-ray computed tomography (XCT). A new fertilization pattern that shallow-deep layer synchronized mechanical sowing was using, rotary tillage mixed fertilization in the shallow layer and 10 cm side-deep band fertilization in the deeper layer. It set five ratios of fertilizer amounts between shallow and deep layers as 0:4 (FD), 1:3 (FL), 2:2 (FM), 3:1 (FH), and 4:0 (F0), with non-fertilization (CK) as the control treatment. The results indicated that layered fertilization effectively improved the rape root conformation and spatial distribution, significantly increased total soil porosity and moisture content, and reduced soil bulk density and resistance (P < 0.05). Additionally, root configuration is closely related to soil pore structure and crop yield. Notably, compared with other treatments, the macroscopic porosity, equivalent pore diameter, hydraulic radius and roundness of FM treatment are significantly improved, and it effectively improves the yield and quality of rapeseed. Correlation analysis showed that the root system configuration parameters were negatively correlated with soil bulk density and resistance but positively correlated with soil moisture content, and macropore morphology parameters and rapeseed yield. Our study demonstrate that layered fertilization can improved rape growth and soil macropore porosity, but its effect depends on good tillage macropore characteristics and distribution created by reasonable fertilization ratio, which provided a theoretical basis for high-yield, efficient, green, and sustainable mechanized direct-sowing production of rapeseed.

Influence of land-use types and topographic slopes on the physico-chemical characteristics of soils in Northwestern Ethiopia

AimsThis study examines the effects of land-use types and slope position on selected soil physico-chemical properties in the Ageza Watershed, Northwestern Ethiopia, focusing on soil fertility depletion and its impact on agricultural productivity.Materials and methodsThe experiment utilized a randomized complete block design (RCBD) with three replications, involving three land-use types and slope positions. A total of 27 soil samples (both disturbed and undisturbed) were collected, prepared, and analyzed for selected physico-chemical properties following standard laboratory procedures. Data were analyzed using two-way ANOVA with SAS software.ResultsSignificant variations in most soil physico-chemical properties were observed across land-use types and slope positions. Soil bulk density, organic carbon (OC), total nitrogen (TN), available phosphorus (Av. P), cation exchange capacity (CEC), and exchangeable bases significantly (P ≤ 0.001) differed among the land-use types and slope positions. The main effects showed significant (P ≤ 0.05) differences in sand, silt, and clay contents across the land-use types. However, pH did not show significant differences (P &amp;gt; 0.05). Soil bulk density, silt content, Av. P, exchangeable bases, and CEC all showed significant (P ≤ 0.01) differences among the slope positions. Forest land had the highest values for clay (46.11%), OC (6.08%), Av. P (20.60 mg/kg), CEC (33.89 cmol (+) kg-¹), and exchangeable cations: Ca²+ (23.72 cmol (+) kg-¹), Mg²+ (4.40 cmol (+) kg-¹), K+ (1.18 cmol (+) kg-¹), and Na+ (0.77 cmol (+) kg-¹). Grazing land exhibited higher silt and bulk density, while cultivated land had higher sand content. Lower slope positions recorded the highest values for clay (47.33%), silt (20.77%), pH (4.90), Av. P (16.61 mg/kg), Ca²+ (20.10 cmol (+) kg-¹), Mg²+ (3.73 cmol (+) kg-¹), K+ (1.00 cmol (+) kg-¹), Na+ (0.66 cmol (+) kg-¹), and CEC (28.71 cmol (+) kg-¹), while bulk density was higher in the upper slope position.ConclusionLand-use types and slope positions significantly influence variations in soil physico-chemical properties and overall soil fertility status. Forest preservation and management are essential to improve the soil fertility in this region.

Predicting Lightweight Powders with Useful Sound Absorption Characteristics from Their Specifications

Powders that absorb sound by longitudinal vibration have either a gentle or sharp sound absorption curve at the first absorption peak frequency. Experiments were performed to investigate the conditions under which longitudinal vibration occurs in powders of various grain sizes and bulk densities. The sound absorption characteristics of the powders were then classified according to their specifications, and the sound absorption coefficients predicted by derived empirical equations were compared with the measured sound absorption coefficients. A threshold value for the areal density per grain layer was identified where lightweight powders at 0.0006 g/cm2 or less demonstrated useful sound absorption characteristics via longitudinal vibration. Powders with smooth (i.e., useful) and sharp (i.e., not useful) sound absorption curves could be further identified by the half-width value at 0.0974 &lt; log f2 − log f1 &lt; 0.119 decade. The bulk density can also be used to identify powders with useful sound absorption characteristics at 0.0868 &lt; ρ &lt; 0.124 g/cm3. A regression analysis was performed to obtain empirical equations expressing the relationship between the areal density per grain layer and first sound absorption peak frequency normalized by the layer thickness.

Enhancing optical properties of Ba-Ni ferrite through nonmagnetic ion doping for sustainable green technologies and renewable energy applications

Barium ferrite powder was produced using a standard ceramic procedure, and its structure and optical properties were investigated. X-ray diffraction analysis (XRD) showed that the powder had a w-type hexagonal structure. The crystallite size was at approximately 35–36 nm, with bulk density and lattice constants increasing as zinc concentration rose. Conversely, X-ray density and porosity decreased with the increasing zinc concentration. This material has useful optical properties, as well as the standard ferrimagnetic properties of barium ferrite, which make it suitable for use in recording media. Ferrimagnetic behavior, which is useful for recording media, occurs because the powder's crystallites have their unit cell axes aligned. Up to the near-infrared part of the spectrum, the powder was found to have a very low absorption coefficient. Both of these properties—an arrangement that gives rise to ferrimagnetism and a corresponding low optical density—make barium ferrite very attractive for high-density recording and microwave applications. Fourier transform infrared spectra of the samples were recorded in the wavenumber range of 400–4000 cm−1 and supported the X-ray diffraction findings by confirming the idea of the formation of W-type hexagonal ferrite by the presence of two prominent peaks at 454 and 591 cm−1 in the FTIR spectra. Zinc addition was also found to enhance the optical properties of the material. The UV–VIS analysis confirms that the band gap energy of Ba-Ni ferrite was indeed reduced by zinc doping. Values decrease from 3.34 eV to 3.20 eV for direct transitions and from 2.96 eV to 2.79 eV for indirect transitions, using Tauc equation. That means that zinc doping enhances the optical properties of Ba ferrite without affecting the hexagonal structure of Ba-Ni ferrite. Moreover, key parameters of optical performance such as the dielectric constant, the extinction coefficient, the penetration depth, and the refractive index show a dramatic increase with a rise in zinc concentration. These attributes make zinc-doped Ba-Ni ferrite a promising optoelectronic material. The material also showed high absorbance in the wavelengths ranging from 334 to 338 nm, which makes it good for the solar cell applications. Overall, zinc-doped Ba-Ni ferrite is a good candidate for sustainable and renewable energy applications. Our study of the optical properties of barium ferrite up to the near-infrared part of the spectrum demonstrated that the powdered material has a very low absorption coefficient. Indeed, the combination of ferrimagnetism and low optical density makes barium ferrite particularly appealing for use in high-density recording and microwave technology applications.

Discovery and characterization of a dense sub-Saturn TOI-6651b

We report the discovery and characterization of a transiting sub-Saturn exoplanet TOI-6651b using PARAS-2 spectroscopic observations. The host, TOI-6651 (mV ≈ 10.2), is a sub-giant, metal-rich G-type star with [Fe / H] = 0.225−0.0450.044[Fe/H] = 0.225−0.045+0.044, Teff = 5940 ± 110 K, and log g = 4.087−0.032+0.035. Joint fitting of the radial velocities from PARAS-2 spectrograph and transit photometric data from Transiting Exoplanet Survey Satellite (TESS) reveals a planetary mass of 61.0−7.9+7.6 M⊕ and radius of 5.09−0.26+0.27 R⊕, in a 5.056973−0.000018+0.000016 day orbit with an eccentricity of 0.091−0.062+0.096. TOI-6651b has a bulk density of 2.52−0.44+0.52 g cm−3, positioning it among the select few known dense sub-Saturns and making it notably the densest detected with TESS. TOI-6651b is consistent with the positive correlation between planet mass and the host star’s metallicity. We find that a considerable portion ≈87% of the planet’s mass consists of dense materials such as rock and iron in the core, while the remaining mass comprises a low-density envelope of H/He. TOI-6651b lies at the edge of the Neptunian desert, which will be crucial for understanding the factors shaping the desert boundaries. The existence of TOI-6651b challenges conventional planet formation theories and could be a result of merging events or significant atmospheric mass loss through tidal heating, highlighting the complex interplay of dynamical processes and atmospheric evolution in the formation of massive dense sub-Saturns.

Soil Physicochemical Properties and Carbon Storage Reserve Distribution Characteristics of Plantation Restoration in a Coal Mining Area

The Bulianta Coal Mine is among the problematic coal mining areas in China that is still creating environmental damage, especially associated with soil destruction. Therefore, a scientific investigation was conducted to establish a scientific basis for evaluating the impact of planted forest on soil physical and chemical properties, as well as the ecological benefits following 15 years of vegetation restoration in the area. The soil physicochemical characteristics and distribution of organic carbon storage in the 0–80 cm layer soils of Pinus sylvestris forests, Prunus sibirica forests, and Hippophae rhamnoides forests restored after 5, 10, and 15 years were investigated. The immersion method was used to determine soil porosity and density followed by the determination of soil indicators, and a statistical ANOVA test was applied to examine the differential effects of different vegetation types and restoration years on soil properties. The results clearly demonstrated the following: (1) The recovery of vegetation was achieved after a period of 15 years, with the average bulk density of the 0–80 cm soil layer as follows: P. sylvestris forest (1.513 g·cm−3) &gt; P. sibirica forest (1.272 g·cm−3) &gt; H. rhamnoides forest (1.224 g·cm−3), and the differences among different forest types were statistically significant (p &lt; 0.05). (2) In planted forests, soil nutrients were predominantly concentrated in the 0–20 cm layer, while soil carbon storage exhibited a decline with an increasing soil depth. (3) The soil carbon storage across the three forest types was as follows: P. sylvestris forest (45.42 t·hm−2) &gt; P. sibirica forest (44.56 t·hm−2) &gt; H. rhamnoides forest (41.87 t·hm−2). In summary, during the ecological vegetation restoration process in the Bulianta Core Mine, both P. sylvestris forest and P. sibirica forest exhibit superior carbon storage capacities compared to H. rhamnoides forest, as well as more effective soil improvement outcomes.

Annual soil erosion characteristics of unpaved roads in the Loess Plateau hilly and gully region, China

The problem of unpaved road erosion is prominent in the Loess Plateau hilly and gully region. Unpaved roads contribute substantially to watershed sediment due to their high soil bulk density, low infiltration rates and extensive network. In this study, a field investigation was conducted on typical unpaved roads within a typical watershed in this region, focusing on assessing the damage state, annual soil loss and the factors influencing erosion in a comparatively wet year. The results showed that the soil erosion from unpaved roads was very severe, with an annual erosion intensity of 470 t hm−2, following three heavy rain events and two rainstorm events in the summer of 2022. The main unpaved roads (MUR) suffered the most severe road erosion, with 22.2 % of road segments experiencing severe erosion with classical gullies. The erosion gullies on the road had an average depth of 16.1 cm and an average width of 36.5 cm, with the widest being 146.0 cm and the deepest being 174.0 cm. The road erosion intensity was significantly related to drainage area, road area, road length and coverage. Road erosion reduced significantly when the land use in the drainage areas of the road was covered with shrub or grass, or road surface was covered with grass or gravel. Our findings offer valuable insights for road construction and erosion prevention in similar terrains.

Research on the distribution of debris flow impact on the upstream surface of the check dam

The impact force of debris flow is not only an important indicator of the risk assessment of debris flow and the strength impact resistance of buildings against debris flow, but also an important parameter in the design of various debris flow prevention projects (such as the check dam and the drainage channel, etc.). The pressure sensors are arranged at different positions (monitoring points) on the upstream face of the check dam. By changing the slope of the drainage channel, the bulk density of debris flow and the slope gradient of the upstream face of the check dam, the time history curves of the impact force at the monitoring points under different experiment conditions are obtained. The characteristic value of the impact force of debris flow acting on the surface of the sand retaining dam is analyzed, and the evolution law of mean value and maximum value of impact force of debris flow at the same detection location with the above conditions is obtained. The mean value and maximum value of debris flow impact force at different detection locations under the same working condition are analyzed to obtain the evolution law of debris flow impact force at different locations, and then the distribution trend of debris flow impact force on the upstream face of the check dam is obtained. The research results provide scientific and reasonable theoretical basis and technical support for the stability analysis of the check dam, so as to better serve the disaster prevention and reduction of debris flow, which will improve the technical level of the debris flow prevention project to a certain extent.