Total Porosity Research Articles

An overview of soil and plant assessment for predicting site quality and recovery strategies of one the largest tailings dam failures worldwide.

Brazil's Fundão dam collapse is one of the world's largest disasters of tailing dam failures. Previous research has evaluated toxic metals and non-metals (Cd, Cr, Ni, Pb, As, Hg) in the same soil samples used in this study, and results have indicated that only Fe and Mn concentrations increased above the original baseline (Melo et al., 2023). Consequently, the present study's focus has shifted towards assessing and integrating changes in soil quality regarding chemical fertility and morphological, physical, and mineralogical attributes in the floodplains post-dam collapse. Soil samples from 0 to 0.2 and 0.2-0.4m depths, and samples of Urochloa sp. were collected along ten transects, spanning 100km perpendicular to the Doce River channel. This sampling strategy targeted specific landscape positions including areas affected by deposited iron tailings (DIT), soil tailing mixture (STM), and control soil (CS) devoid of iron tailing interference. Results showed no discernible alterations in Ca, Mg, K, and P concentrations in Urochloa sp., and the most severe negative impacts observed regarded the replacement of kaolinitic pre-disaster matrix for hematitic matrix, reduction in organic carbon, and the prevalence of sand and silt particles. These factors collectively contributed to triggering: (i) decrease in chemical fertility and cation exchange capacity and (ii) significant decline in physical quality, evidenced by increased density and reduced total porosity and macroporosity. Addressing these adverse effects would require the augment of organic matter levels and offset the dominance of the hematitic matrix in the DIT. Furthermore, it is imperative to decompact the DIT by mechanized or plant cultivation means.

Design and performance of a foamed ceramic prepared by sintering using boron carbide as a foaming agent

To meet the requirements of microwave penetration in military applications, the technical potential of preparing foamed ceramics (FCs) with low permittivity and reduced preparation costs by using desalted sea sands as the main raw material and boron carbide (B4C) as a foaming agent was investigated. The results of the orthogonal experiment demonstrate that the FCs prepared from a material system containing 3 wt% B4C, 2 wt% Fe2O3 and 4 wt% Na2CO3 exhibit the optimal overall performance. The performance of the FCs is strongly influenced by the sintering temperature, but less so by the sintering time. The FCs sintered at 1000 °C for 10 min have a high total porosity of 72 %, a high compressive strength of 9.7 MPa due to their homogeneous internal pore structure with small pore diameter, a high closed porosity of 71 % due to their dense smooth surface and intact pore walls, and a low permittivity of (2.09–2.25)+j(0.014–0.019) in the X–band due to their high porosity and simple composition, indicating that they are a promising multifunctional material for microwave penetration.

3D printing of metal parts using a highly-filled thermoplastic filament

Purpose This study aims to develop a highly loaded filament with spherical metallic particles for fused filament fabrication (FFF) technology. The research focuses on optimizing powder loading, printing parameters and final processes, including debinding and sintering, to produce successful metal parts. Design/methodology/approach The optimal powder loading was identified by measuring mixing torque and viscosity at various temperatures. The filament was extruded, and printing parameters − particularly printing speed to ensure proper material flow − were optimized. Different filling patterns were also examined. After printing, the polymeric binder was removed and the parts were sintered to form the final metal components. Findings The optimal powder loading was determined to be 55 vol.%. The best surface quality was achieved with an optimized printing speed of 5 mm/s. Parts printed with various infill patterns were studied for differences in open, closed and total porosity, showing a strong link between porosity and infill pattern. Originality/value This comprehensive study provides new insights into manufacturing metal parts using FFF technology. It fills a gap in the literature regarding feedstock viscosity and shear rate in highly loaded metal filaments during FFF. Additionally, it uniquely examines the open, closed and total porosity of metal parts printed with different infill patterns.

Moulding Test and Process Parameter Optimization of Biomass Seedling Pots for Cow Dung and Corn Stover

In order to determine the optimal moulding process parameters of biomass seedling pots prepared from fermented cow dung mixed with corn stover, the moulding pressure, baking time, and baking temperature of biomass seedling pots were taken as the influencing factors, and the expansion rate, durability rate, wet swelling rate (48 h), and resistance to damage were taken as the evaluation indexes, and the Box–Behnken design of the response surface method was used to analyze the significance of interactions among the different influencing factors in the moulding process of biomass seedling pots and to optimize the moulding process. The experiment was conducted in the Biomass Laboratory of Heilongjiang Bayi Agricultural University. The response surface method Box–Behnken design was used to analyze the significance of the interaction between different influencing factors in the biomass seedling pots moulding process and optimize the moulding process. The results showed that the optimum moulding process conditions obtained using the Box–Behnken design were the following: a moulding pressure of 520.393 kN, baking temperature of 202.870 °C, and baking time of 8.573 min. The model was validated by testing and a response value of 10.522% was obtained for expansion, 99.598% for durability rate, 11.145% for wet swelling (48 h), and 4503.545 N for resistance to damage. The experimental verification showed that the deviation of the actual value obtained under this condition from the predicted value is less than 5%, indicating that the model reproduces well and meets the experimental requirements. Based on the optimal moulding process conditions determined in this experiment, the total porosity, EC, and pH of the Biomass seedling pots were determined to be 67.32%, 1.63 mS/cm, and 6.7, respectively, which met the seedling requirements.

Microstructure, thermal, and mechanical properties of hierarchical porous silicon carbide made by direct ink writing

AbstractHierarchical porous silicon carbide (SiC) ceramics were fabricated by combining particle‐stabilized emulsions and three‐dimensional (3D) printing. Direct ink writing (DIW) was used as the 3D printing technique. The formulation for successful printing is discussed in relation to the rheology of the emulsions. The SiC emulsions were able to be printed with a lower storage modulus (G′) and apparent yield shear stress (τy) than previously reported SiC ink pastes. The printed and sintered porous SiC ceramics possess a total porosity of 73.7% with an average pore size within the filaments of 2.2 µm in diameter. A hierarchical pore structure that contains pore sizes of about 250 µm, around 1–10 µm and smaller than 0.5 µm can be observed in the microstructure and pore size distribution. The mechanical properties showed a good strength‐to‐density ratio, and the thermal conductivity was reduced to 4.9 W/m·K. This study provides a new reliable approach for fabricating hierarchical porous SiC ceramics with low thermal conductivity.

Recycling of RAP (Reclaimed Asphalt Pavement) as aggregate for structural concrete: experimental study on physical and mechanical properties

The replacement of natural aggregate in concrete with artificial and/or recycled one has recently gained attention as meaningful strategy to reduce the environmental impact of structural concrete and promote circular economy principles. This study investigated the possibility to use Reclaimed Asphalt Pavement (RAP), in the “as received conditions”, as a partial or complete substitution of natural aggregate for structural concrete. RAP aggregate was firstly characterized in terms of grain size distribution, density, assessment of fines, chloride content, moisture content and water absorption. Subsequently, a total of twenty-four concrete mixes were designed, considering two cement types, two w/c ratios and several aggregate substitution percentages. For each mix, properties at the fresh and hardened state were investigated, such as workability, density and total open porosity, compressive strength, dynamic modulus of elasticity, and electrical resistivity. Results showed that RAP has a good potential to be used in reinforced concrete, provided that different water absorption and moisture content are considered in the mix design. RAP concrete was characterized by a lower density and increased total open porosity; however, an accurate tailoring of the concrete recipe could compensate the strength loss for several applications. Other properties, such as electrical resistivity and the relationship between dynamic modulus of elasticity and compressive strength did not result significantly altered by the presence of RAP.

Effects of liquid accelerators on long-term mechanical strength development and microstructural changes of wet-mixed shotcrete

The significant long-term strength loss of shotcrete can greatly affect the safety and stability of underground shotcrete structures. Developing high-quality liquid accelerators remains an indispensable research direction and a viable approach to mitigate challenge. This study synthesizes three distinct kinds of liquid accelerators - alkali-free fluorine-free (GJ), alkali-free fluorine-containing (MJ), and low-alkaline (JJ) and investigates their effects on the long-term mechanical strength of wet-mixed shotcrete. Moreover, changes in the phase composition and microstructure of accelerated shotcrete were explored utilizing X-ray diffraction, thermogravimetric analysis, mercury intrusion porosimetry, and scanning electron microscopy techniques to reveal underlying mechanisms. Results indicate that accelerated cement paste and mortar with a 6 wt% fixed dosage of liquid accelerators exceeded the prescribed basic performance indices (setting time and 28-day compressive strength ratio) for shotcrete applications. Among the accelerators, the alkali-free fluorine-containing type exhibited the most beneficial effect on long-term strength, attributed to increased C-(A)-S-H formation from added Al and Si into the system. Morphological and crystal composition changes in hydrate phases, notably the transformation of ettringite to AFm and additional formation of monosulfate and hemicarbonate, increased the solid volume, refined pore structure and reduced total porosity, thus enhancing long-term strength. This study offers valuable insights into the synthesis and optimization of main accelerator components to mitigate long-term strength loss in shotcrete for practical engineering applications.

Soil water repellency under Eucalyptus stands of different age and its relationship with soil hydrological function and soil organic matter

Eucalyptus stands can modify soil hydrological functioning, by several mechanisms including the effect of the growing root system, changes in soil organic matter (SOM) and the occurrence of soil water repellency (SWR). This effect is expected to evolve with time, as tree root system develop and SOM is formed from tree litter. SWR can prevent water from entering the soil, reducing infiltration, while the effect of roots and SOM can improve structure, favoring infiltration. The aims of this study were: i- to determine the influence of Eucalyptus stands of different ages on soil physical and hydraulic properties and SWR phenomena; ii- to evaluate the effects of SOM content and composition on SWR; iii- to determine the relationship between SWR and soil physical properties; iv- to compare different methodologies for SWR evaluation. The soil studied was a in a silty loam Typic Argiudoll with Eucalyptus stands of 3, 7, 11 and 32 years. Samples were taken to determine saturated and near saturation hydraulic conductivity, water retention curve, total organic carbon and different fractions of SOM, and SWR. Different parameters were used to estimate SWR, including the repellency index (RI), water repellency cessation time (WRCT), modified repellency index (RIm), and a qualitative analysis of the shapes of cumulative infiltration curves. As main results, a reduction in total porosity (TP) in the first years of Eucalyptus plantation was found, followed by a steep increased in TP, mainly due to an increase in microporosity. Hydraulic conductivity decreased with stand age, which was attributed to a decrease in macro and mesoporosity and porosity connectivity. SOM and most SOM fractions were not affected by stand age. RI was a consistent method to estimate SWR in Eucalyptus stands, while WRCT and RIm determination was more difficult when non classical shapes of infiltration curves were obtained.

Effects of surface tension and contact angle on pore structure development of coal samples under chemical solution erosion

To explore the influence of surfactant concentration on the pore structure and permeability of coal samples during the chemical enhancement of coalbed methane production, different kinds and different concentrations of surfactants were added to the chemical solution, and the coal samples were soaked. Methods such as low-field nuclear magnetic resonance testing (NMR), fractal theory, permeability testing, surface tension testing, and contact angle testing were employed to analyze the variation patterns of coal sample pore structure, fractal characteristics, and permeability, and to explore the correlation between surface tension, contact angle, and the degree of pore structure development. The results show that the increase in total porosity of coal samples, the increase in the seepage pore porosity, the decrease in Dt, and the growth rate of permeability increase with the increase in surfactant concentration, and are negatively correlated with the surface tension of the solution and the contact angle of the coal-solution interface, while the decrease in Ds is not significantly correlated with surfactant concentration, surface tension, or contact angle. In terms of the erosion effect of a chemical solution on coal samples, the influence of contact angle is greater than that of surface tension, while surface tension has the greatest impact on the development of adsorption pores. By adding different surfactants, the surface tension of the chemical solution and the contact angle of the coal-solution interface can be controlled, further promoting the erosion of coal samples, which is of positive significance for the chemical enhancement of coalbed methane production.

Effects of biochar application on soil properties and the growth of Melissa officinalis L. under salt stress

Soil salinization is one of the world's most seriously ecological issues. The application of biochar may enhance the properties of the soil and lessen the harm that salt stress causes to plants. In this study, we used the cuttings of Melissa officinalis as experimental materials. The method of pot experiment was used to explore to explore the effects of different concentrations of biochar (0, 10 %, and 20 % w/w) on soil properties and plant physiological characteristics under salt stress (0, 0.20 %, and 0.60 % NaCl+Na2SO4). The results indicate that the physicochemical properties of soil and the plant growth were decreased impacted with increasing salinity level, and these negative impacts were decreased traits were improved with the application of biochar. It was discovered that the application of biochar could increase the soil water holding capacity, total porosity, available P and K content, and soil enzyme activity while also decreasing the soil bulk density under salt stress. Biochar addition promoted the accumulation of plant biomass and the acquisition of nutrients, and reduced Na content in plants. With the addition of biochar, malondialdehyde (MDA) content and electrolyte leakage displayed a significant decrease under salt stress. A reduction in the osmotic substances and secondary metabolite accumulation in the leaves was also evident. The presented results reveal that biochar can contribute to protect M. officinalis against salt stress by alleviating the oxidative stress. Among the test samples, the 20 % biochar application had the best performance, suggesting that this is an advantageous method for improving soil properties and lessening the harm caused by salt stress on M. officinalis.

The impact of pore heterogeneity on pore connectivity and the controlling factors utilizing spontaneous imbibition combined with multifractal dimensions: Insight from the Longmaxi Formation in Northern Guizhou

The heterogeneity of shale pores, a crucial factor in the occurrence and migration of shale gas, exerts a significant impact on the pore connectivity. Pores exhibiting a range of structural attributes to the complexity of pore connectivity. A comprehensive study into the impact of pore heterogeneity on pore connectivity in shale is lacking. This study aims to explore the impact of pore heterogeneity on pore connectivity in shale and the primary controlling factors of pore connectivity. Shale pore connectivity, pore structures, mineral composition, and geochemical parameters were assessed using various tests, including spontaneous imbibition, adsorption, mercury intrusion capillary pressure (MICP), focus ion beam-scanning electron microscopy (FIB-SEM), sulfur and carbon analysis, vitrinite reflectivity, and X-ray diffraction (XRD). Pore heterogeneity was quantitatively analyzed using the multifractal dimensions method. Results show that the increased heterogeneity of pore structure and surface roughness facilitating the potential for increased connectivity. The presence of well-developed micro-mesopores within the organic matter, alongside numerous disconnected and independent pores, contributes to an increase in pore heterogeneity. Micro-mesopore structures have a more pronounced impact on pore heterogeneity than macropores. The heterogeneity of the pores is predominantly influenced by variations in the PV and SSA of micro-mesopores. Furthermore, the heightened heterogeneity of pore structure (D1) and surface roughness (D2) leads to a more complex pore structure with increased roughness, promoting the potential for enhanced connectivity through additional throats and facilitating the formation of secondary microfractures. Shale cores characterized by high total organic carbon (TOC) content, porosity, and clay mineral content are conducive to improved pore connectivity. Conversely, the increase of thermal evolution maturity of shale in the over-mature stage is not conducive to the increase of pore connectivity. Thermal evolution maturity, TOC content, and clay mineral are key factors that control pore heterogeneity, further affecting the connectivity of shale pores. High pore connectivity is conducive to spontaneous imbibition capacity and the formation of hydraulic microfractures, promoting the migration of shale gas.

Applicability of ensemble learning in total organic carbon and porosity evaluation of shales

Accurate evaluation of total organic carbon (TOC) content and porosity is of paramount significance for assessment and target interval selection for shale reservoirs. This study takes shales from the western Chongqing area as an exemplary case to delve into the applicability and reliability of ensemble learning in evaluating TOC content and porosity. The results indicate that although both Light Gradient Boosting Machine (LightGBM) and Random Forest (RF) algorithms are suitable for evaluating TOC content and porosity in shales, LightGBM algorithm is preferred due to its comprehensive advantages, including higher accuracy, stronger generalization capability, and faster operating speed. For TOC content evaluation, the four most important logging parameters identified by LightGBM and RF are consistent, but exhibit different orders: DEN (compensated density) > GR (gamma ray) > U (uranium) > CNL (compensated neutron) and DEN > U > GR > CNL, respectively. For porosity evaluation, LightGBM and RF identify the same type and order of the three most important logging parameters: AC (acoustic transit time) > DEN > U. This similarity may be attributed to the fact that both algorithms utilize Classification and Regression Tree (CART) as base learners. The dependence plots between SHAP (SHapley Additive exPlanations) values and logging parameters reveal that the role of each logging parameter in the evaluation model is segmented, rather than exhibiting a continuous linear contribution. In conclusion, given the exceptional performance of ensemble learning algorithms, they, especially LightGBM algorithm, are highly recommended for shale evaluation.

The effect of unintended porosity on the first compressive stress maximum of alumina hollow sphere-filled bimodal composite metal foams

Bimodal composite metal foams made from Al99.5 aluminium and quasi-eutectic Sr-modified AlSi12 matrix were investigated, where the bimodality was introduced by two alumina hollow sphere sets with nominal diameters of Ø7.0 and Ø2.4 mm in various volume concentrations. The research aimed to determine the effect of the cell structure (especially the unintended porosity) on the first compressive stress maximum, depending on the applied matrix material. The various features of the cell structure were quantitatively measured in composite metal foams by filtering raw computed tomography analysis data. The casting porosity, the wetting porosity, the porosity from the various-sized hollow spheres, and the partially matrix-filled hollow spheres have been successfully distinguished based on volumetric and geometrical conditions, such as sphericity and compactness. The unintended porosity (as the sum of the casting porosity and the wetting porosity) influences the first compressive stress maximum of the Al99.5 matrix composite metal foams. In contrast, for the AlSi12Sr bimodal foams, the results correlated with the total porosity values. The first compressive stress maximum could be estimated well from the compressive yield strength of the matrix and the total porosity of the foam.

Modification of the polymeric admixture based on polycarboxylate ether using silica-derived secondary materials obtained from fly ash and the efficiency of its application in concrete

The rising energy prices and the costs of CO2 emissions into the atmosphere are forcing the construction industry to search for ways to reduce cement consumption in concrete technology by optimizing concrete mixtures and making greater use of chemical admixtures. The scientific problem lies in understanding how polymers modified with silica-derived secondary materials, such as those obtained from fly ash (e.g., synthetic zeolites, mesoporous silica), interact with the concrete matrix and influence their durability and strength. The present study investigated the effect of a polymeric admixture based on polycarboxylic ether (PCE) modified with silica-derived secondary materials obtained from fly ash (synthetic zeolites, mesoporous silica) on the physical and mechanical properties of concrete. The study considered the effect of the modified polymer admixture dosed in 3 different amounts (0.4%, 0.8% and 1.2%) by weight of cement on the fresh properties of the concrete mixture, i.e. consistency and air content. The research scope also included determining the physico-mechanical properties of the concretes and investigating the effect of the modified admixture on the frost durability of the cement composite. In order to study the modification of the concrete microstructure, XRD phase analysis and air pore structure analysis by MIP were carried out. The study showed an increase in compressive strength after 28 days of curing in concretes containing the modified polymer of about 8-12% compared to the reference concrete. In addition, it was observed that strength increased with increasing admixture dosage. The resulting pore structure, contributed to improving the frost resistance of the concretes by reducing compressive strength loss from about 14% in reference concretes to about 2-9% in concretes with the modified polymer after 150 cycles of alternating freeze-thaw. At the same time, it was observed that the use of the modified polymer resulted in an increase in weight absorption from 2% do 4.5%, a more than twofold increase in depth of penetration of water under pressure and a more than 70% increased total porosity. In conclusion, the polymer-modified MCM-41 can positively affect the mechanical and durability properties of concrete, but it causes a change in the pore structure, which could have a negative effect on water absorption and total porosity.

Effects of aggregates and fibers on the strength and permeability of concrete exposed to low vacuum environment

The performance and regulation of concrete in low vacuum environments are receiving increasing attention. This study investigates the effects of aggregates and fibers on the strength and permeability of concrete in a low vacuum environment, using varying gradients of sand ratios (37.5 %, 40 %, and 42 %) and aggregate-to-binder ratios (3.27, 3.92, and 4.14). Three types of non-metallic fibers are utilized: polyethylene (PE), polyvinyl alcohol (PVA), and glass fibers. Evaluations focus on concrete strength, mass loss, gas permeability, capillary water absorption, and porosity. Results indicate that higher sand and aggregate-to-binder ratios enhance both flexural and compressive strength. Fiber incorporation improves flexural and compressive toughness, with PE fibers showing the most significant toughening effect. The low vacuum environment increases the strength of the concrete but reduces its axial compression toughness ratio and increases brittleness, while fiber incorporation helps improve the compression toughness of the concrete. Higher sand and aggregate-to-binder ratios reduce mass loss and accelerate drying equilibrium, while fibers increase mass loss and prolong drying equilibrium, with PVA fibers causing greater mass loss. The pattern of concrete mass loss can be explained by the tortuosity of the moisture diffusion path. Additionally, low vacuum significantly increases the gas permeability of concrete. Enhancing the sand and aggregate-to-binder ratios reduces permeability both before and after low vacuum treatment. Although fibers increase the gas permeability, they help mitigate this increase under low vacuum condition. Capillary water absorption tests reveal that concrete under low vacuum condition has a significantly higher water absorption rate compared to air-drying condition. Increasing sand and aggregate-to-binder ratios reduces water absorption and capillary water content, whereas fibers have the opposite effect. Porosity tests show that moisture migration in a low vacuum environment is mainly related to permeable porosity, while total porosity is more closely related to compressive strength.

Sand Production Prediction and Management Using a One-Dimensional Geomechanical Model: A Case Study in NahrUmr Formation, Subba Oil Field

Sand production in sandstone reservoirs is a complex problem for oil and gas companies. This problem can damage downhole equipment and surface production facilities. This paper presents a sand production case and quantifies sand risks for the NahrUmr formation located in Subbaoilfied.The risk of sanding or rock failure is commonly observed during production phases as well as drilling operations. A (1D) mechanical earth model was created using wireline log data and core data for estimating the formations mechanical properties.The extrapolation method is utilized for vertical stress prediction, whereas pore pressure and static Young’s modulus were calculated using Slowness Eaton method and John Fuller correlation respectively. The poro-elastic model was used to determine horizontal principal stresses and hydrocarbon intervals susceptible to sand production issues.The purpose of this study was achieved using Tech-Log software. Sand onset intervals are firstly predicted as an open hole using ten methods: Loading factor (LF), Critical drawdown pressure (CDDP), B-index, schlumberger (Sc), Elastic combination index (Ec-index), Interval Transit-Time (DTc), Total porosity method (PHIT), unconfined compressive strength (UCS), Shear modulus to bulk compressibility ratio (G/Cb), and shear failure method. Approximately ten methods refer to the same intervals that can produce sand. Secondly, sand depths were predicted by representing the well according to what actually existed as a cased hole by calculating the critical drawdown pressure (CDDP), which is calculated at various depletion rates (0%, 15%, 25%, and 35%) in order to measure the effect of reservoir pressure depletion on sand production. The results show that as the rock strength is increased, the amount of sand-free drawdown and depletion becomes larger. Also, a single-depth analysis was conducted for problem intervals, indicatg a sandwillproducefromdepth of 2527.7 m under certain conditions. Therefore, it is necessary to install sand control equipment in this well.

Production and Characterization of Porous Anorthite Ceramics Using Sugar Process Solid Waste, Chamotte and Coal Powder Additives

Press filter cake is a solid waste produced during sugar production process and includes carbonates and organic components. In this study, coal powder in different percentages (from 10 wt.% to 50 wt.%) was mixed with 35 wt.% press filter cake and 65 wt.% chamotte composition to produce porous anorthite ceramic products with different apparent porosity percentages. The anorthite phase was observed as the dominant crystalline phase in all fired samples. The firing shrinkage values sharply increased after adding higher than 40 wt.% coal powder to composition. In addition, apparent porosity values were changed from 49% to 70%. Compressive strength values reduced from 18 MPa to 1.73 MPa while percentages of ground coal were increasing. Microstructural analysis also showed that the porosity values of the sintered samples showed important changes depending on the amount of coal additive. The thermal conductivity values showed a reduction from 0.113 W/mK to 0.064 W/mK while increasing the percentage of ground coal. Micro-computed tomography (Micro CT) analysis was performed for 40wt. % coal powder added composition and the total porosity value was found as 60.2%.

Investigation of Phase Transformation and Fracture Pattern as a Result of Long-Term Chewing Simulation and Static Loading of Reduced-Diameter Zirconia Implants.

While zirconia implants exhibit osseointegration comparable to that of titanium, concerns arise regarding low-temperature degradation and its potential impact on fracture strength. This study investigated the phase transformation and fracture characteristics of zirconia dental implants after aging through chewing simulation and subsequent static loading. The experimental setup involved 48 one-piece monobloc zirconia implants with diameters of 3.0 mm and 3.7 mm that had straight or angled abutments, with crown restorations, which were divided into six groups based on intraoral regions. The specimens underwent chewing simulation equal to five years of oral service, which was followed by static loading. Statistical analyses were performed for the data obtained from the tests. After dynamic and static loadings, the fractured samples were investigated by Raman spectroscopy to analyze the phase composition and micro-CT to evaluate fracture surfaces and volume changes. According to the results, narrow-diameter zirconia implants have low mechanical durability. The fracture levels, fracture patterns, total porosity, and implant fracture volume values varied according to the implant diameter and phase transformation grade. It was concluded that phase transformation initially guides the propagation of microcracks in zirconia implants, enhancing fracture toughness up to a specific threshold; however, beyond that point, it leads to destructive consequences.

Depth Wise Distribution of Soil Physico-Chemical Properties and Nutrients Across a Toposequence Located at KVK Farm, Sakhigopal, Odisha, India

This study aims to identify soil-related constraints for crop production and provide insights for soil management by analyzing soil profiles across different topographic positions (upland, medium land, and lowland) at KVK farm, Sakhigopal, Puri located in the East and Southeastern Coastal Plain Agro-Climatic Zone of Odisha. The profiles were evaluated for key physico-chemical properties and nutrient contents, revealing significant variations influenced by topography. The results showed that the soil's physical and chemical properties and available nutrient status showed distinct variations among the pedons. Among soil physical properties, the sand percentage, bulk density, and particle density increased with soil depth. Whereas, the clay percentage, total porosity, and water-holding capacity decreased with soil depth. Soil pH ranged from 6.32 to 7.50 and the electrical conductivity was recorded below 1 dSm-1. The organic carbon content ranged from 8.6 to 10.3 g kg-1. In general, soil pH, base saturation, and exchangeable cations increased with soil depth. On the other hand, soil organic carbon content and exchangeable acidity decreased with soil depth. Available nitrogen, phosphorus, potassium, and sulphur contents decreased with soil depth. However, in general, their concentrations increased along the slope (towards low land), which may be attributed to increased levels of organic carbon and clay contents in the lower topographic positions owing to high moisture content and higher cropping intensity. The findings of this study provide valuable insights regarding soil property characterisation across a transect for sustainable land use planning.

Unleashing innovation: 3D-printed biomaterials in bone tissue engineering for repairing femur and tibial defects in animal models - a systematic review and meta-analysis.

3D-printed scaffolds have emerged as an alternative for addressing the current limitations encountered in bone reconstruction. This study aimed to systematically review the feasibility of using 3D bio-printed scaffolds as a material for bone grafting in animal models, focusing on femoral and tibial defects. The primary objective of this study was to evaluate the efficacy, safety, and overall impact of these scaffolds on bone regeneration. Electronic databases were searched using specific search terms from January 2013 to October 2023, and 37 relevant studies were finally included and reviewed. We documented the type of scaffold generated using the 3D printed techniques, detailing its characterization and rheological properties including porosity, compressive strength, shrinkage, elastic modulus, and other relevant factors. Before incorporating them into the meta-analysis, an additional inclusion criterion was applied where the regenerated bone area (BA), bone volume (BV), bone volume per total volume (BV/TV), trabecular thickness (Tb. Th.), trabecular number (Tb. N.), and trabecular separation (Tb. S.) were collected and analyzed statistically. 3D bio-printed ceramic-based composite scaffolds exhibited the highest capacity for bone tissue regeneration (BTR) regarding BV/TV of femoral and tibial defects of animal models. The ideal structure of the printed scaffolds displayed optimal results with a total porosity >50% with a pore size ranging between 300- and 400µM. Moreover, integrating additional features and engineered macro-channels within these scaffolds notably enhanced BTR capacity, especially observed at extended time points. In conclusion, 3D-printed composite scaffolds have shown promise as an alternative for addressing bone defects.