Relative Density Research Articles

Adjustment for urinary dilution in the measurement of environmental chemicals: Considerations for the use of creatinine versus specific gravity

Adjustment for urinary dilution in the measurement of environmental chemicals: Considerations for the use of creatinine versus specific gravity

Landslide susceptibility mapping using modified frequancy ratio method in Correb area, South Wollo, North-Western Ethiopia

Correb area in Mekdela Woreda, South-Wollo Zone, North-Western Ethiopia is one of the most landslide affected region. The primary aim of this study was to assess the landslide susceptibility of the area and create a landslide susceptibility map. A bivariate statistical frequency ratio model was used to accomplish this goal. Using fieldwork and Google Earth picture interpretation, a map of landslides was made. A total of 524 landslides were identified and then classified in to training landslide (75%) for model development and validation landslide (25%) for model validation. Eight landslide causative factors slope, aspect, elevation, distance to drainage, distance to spring, slope material, distance to lineament, and vegetation cover were integrated with training landslides in order to determine frequency ratio value(weight) for each class of landslide causative factors. Furthermore, each causative factor’s prediction rate or weight was established. Relative frequency values were allocated to the appropriate factor classes and prediction rate values were allocated to the appropriate causative factors and summed using a raster calculator algorithm in order to produce the landslide susceptibility map. The final landslide susceptibility map revealed that 27.54% (31.52 km2) of the study area falls under very low susceptible, 30.35% (34.74 km2) low susceptible, 21.36% (24.44 km2) moderate susceptible, 14.74% (16.88 km2) high susceptible, and the rest 6.01% (6.88 km2) as very high susceptible. This shows that more than 20% of the area has probability and risk of landslide while about 80% has relatively low probability and risk of this natural hazard. The performance of modified frequency ratio model for landslide susceptibility mapping was validated using simply overlay, relative landslide density index, and receiver operating characteristics curve. Both training and validation landslides were rare in the very low and low susceptibility classes and strongly concentrated in the high and very high susceptibility classes, according to validation using simple overlay and the relative landslide density index. The implemented model performed exceptionally well, as seen by the receiver operating characteristics curve, which showed 82.6% success rate and an 83.1% prediction rate. In general, the model produced reasonable accuracy. The resultant map would be useful for general land use planning, site selection, and landslide prevention and mitigation programs.

Preparation, Quality control and Standardization of a Destructive Distillate <i>Swasakasa Nei</i> (SKN), A Traditional Siddha Herbal Pharmaceutic for <i>Swasakasam</i> (Bronchial Asthma)

Standardization is essential to ensure the quality and reliability of traditional medicines. This study aimed to collect, authenticate and purification of raw materials, preparation of <i>Swasakasa Nei</i> (SKN) according to SOP, and Quality evaluation and Standardization procedures following Pharmacopoeial Laboratory of Indian Medicine (PLIM) guidelines. SKN, prepared as <i>Kuzhithylam</i>, is used to treat <i>Swasakasam</i> (Bronchial Asthma) in the Siddha system of medicine. The organoleptic characters of <i>Swasakasa Nei</i> reveal that SKN was a black, thick semisolid with a smoky odour, greasy consistency, and free-flowing nature drug. Physicochemical analysis showed values for Saponification Value (202.19), Iodine Value (30), Acid Value (7.25%), Peroxide Value (0.58%), Refractive Index (1.462), Specific Gravity (0.9131 g/ml), Loss on Drying (34.17%), Total Fatty Matter (60.18%), Free Fatty Acids (1.06%), and Unsaponifiable Matter (0.98%). The congealing point was 19°C, with no mineral oil and definite oxidation on rancidity. HPTLC fingerprint analysis revealed multiple prominent peaks at various wavelengths. Microbial contamination tests showed no specific microbes, and aflatoxin assays confirmed SKN was free from Aflatoxins B1, B2, G1, and G2. Pesticide residue analysis detected no organochlorine, organophosphorus, or pyrethroids, and heavy metal analysis showed no trace elements or heavy metals. These standards affirm the authenticity, genuineness, and safety of SKN, contributing to its scientific validation.

Modeling and Experimental Validation of Pre-Chamber Jet Penetration Considering Jet Density and Ejection Pressure Variations

Abstract Although pre-chamber (PC) is regarded as a promising solution to enhance ignition in lean-burn gas engines, a lack of comprehensive understanding of PC jet penetration dynamics remains. This study proposed a zero-dimensional (0-D) model for PC jet penetration, considering the mixing of combustion products and unburned gases and floating ejection pressure. A combustion completion degree was defined employing fuel property and heat release to estimate varying jet density. Pressure differences between PC and the main chamber (MC) were referred to as the ejection pressure. Then, this model was validated against experiments from a constant volume chamber and a rapid compression and expansion machine with CH4-H2 blends at different equivalent ratios. Results showed that the proposed model can provide a good prediction in stationary and turbulent fields with the calibrated model coefficient. The overall jet penetration exhibits a t0.5 dependence due to its single-phase characteristic and the relative lower density compared to ambient gas in MC. The flame propagation speed and heat release in PC influence the combustion completion degree at the start of jet ejection, the mass fraction of burned gas in jet increases with the equivalent ratio. Jet penetration is primarily driven by ejection pressure, with tip dynamics barely affected by the pressure difference after the peak. Tip penetration intensity increases with increased fuel equivalent ratio and H2 addition, owing to the faster flame propagation. These findings can offer useful suggestions for model-based design and combustion model development for gas engines.

Regenerated Natural Minerals towards Double‐layers Heterojunctions Metal@metal‐sulfides with Remarkable Conductivity for Ultra‐fast Sodium‐ion Storage

AbstractAttracted by the high specific capacity and energy density, transition metal‐sulfides exhibit great application potential as sodium‐ion batteries anode, but still suffer from the uncontrolled separation of M/S phase and inferior conductivity. Herein, the flower‐like Fe1‐xS@Sb@C (FF) is rationally tailored, accompanied by double‐layer heterojunctions and C–S–Sb/Sb–S–Fe “bridge” bonds. Meanwhile, the bimetallic phases/boundary defects and built‐in electric fields are formed with a strong electronic coupling effect, effectively alleviating the separation of the M/S phase (Fe/Sb and S), and significantly enhancing ion/e− conductivity. As expected, FF delivers an ultra‐fast sodium‐ions storage rate capacity of 436.5/334.3 mAh g−1 even at 10.0/20.0 A g−1. When the operation temperature is lowered to ‐5 °C, the reversible capacity can still remain at ≈349.7 mAh g−1. Assisted by the detailed kinetic analysis and theoretical calculations, their great ion‐storage abilities mainly derive from improved interfacial Na+/e− transfer and surface/near‐surface redox behaviors. Moreover, the reassembling evolution of active phases is revealed by in/ex situ techniques, further demonstrating the stable adsorption/anchoring of intermediate reaction products Fe/Sb–S phases on the heterointerface, accompanying high reversible conversion‐alloying reaction. Given this, this interesting work is anticipated to offer an in‐depth insight into capacity fading mechanism, and effective strategy to design metal‐sulfur anodes for advanced sodium‐ion systems.

Strength comparison for fully dense zirconium diboride ceramics tested by different methods

AbstractThe strength of zirconium diboride ceramics was tested by three different methods, 3‐point flexure, 4‐point flexure, and compression. Nearly full‐density ceramics were obtained by hot pressing commercial ZrB2 powder with the addition of .5 wt.% carbon as a sintering aid. The thermal properties and hardness were studied for ZrB2 milled with ZrB2 and WC media. Based on phase purity and higher thermal conductivity, ZrB2 ceramics prepared from powders milled with ZrB2 media were selected for mechanical property studies. The strength in 3‐point flexure was 546 ± 55 MPa. The flexure strength was 476 ± 41 MPa in 4‐point bending, which was ∼20% higher than the previously reported value of 398 MPa for ZrB2 with similar grain sizes due to higher relative density and lower impurity contents. Compression testing was performed at room temperature, and the strength was 1110 ± 358 MPa. Finally, the fracture toughness of pure ZrB2 ceramics was determined by the chevron‐notched beam method to be 3.6 ± .7 MPa m1/2. The strength and fracture toughness values are higher than those previously published for ZrB2 ceramics and can be attributed to higher density and lower grain size. The strength‐limiting flaw sizes were comparable to the grain size, suggesting that porosity and impurity phases did not play a significant role in the strength of these ceramics.

Investigation of the Effect of Relative Density on the Dynamic Modulus and Damping Ratio for Coarse Grained Soil

As the critical dynamic parameters for soil, an extensive examination of the dynamic elastic modulus Ed and damping ratio λ in coarse-grained soil is of significant theoretical and practical importance. Currently, there is a scarcity of experimental equipment and methods for measuring the dynamic elastic modulus and damping ratio of coarse-grained soils. Moreover, studies examining the influence of relative density on these parameters in coarse-grained soils are largely absent. To investigate the behavior of the dynamic elastic modulus and damping ratio in coarse-grained soil under varying relative densities, a number of dynamic triaxial tests were conducted on a specific coarse-grained soil using the DYNTTS type dynamic triaxial test apparatus. The findings reveal that, under various gradations, the Ed of coarse-grained soils exhibits a decreasing trend with increasing dynamic strain, a trend that intensifies with higher relative densities. Additionally, as relative density increases, the degradation rate of the dynamic shear modulus ratio Gd/Gdmax to dynamic shear strain γd curve escalates. The maximum dynamic shear modulus Gdmax rises with increasing relative density Dr, displaying a linear relationship between Gdmax and Dr. Furthermore, both the increasing rate of λ to γd curve and the maximum damping ratio λmax progressively diminish with the escalation of relative density Dr. Notably, the maximum damping ratio has a power function relationship with the relative density.

The Analysis of Overflow Occurrences In Fuel Oil Purifiers At MV Dahlia Merah

A purifier is needed to maintain fuel quality and support ship engine performance. A purifier is a device that is a separator for oil from water and dirt based on its specific gravity. This research aims to determine the causes and impact of overflow on the fuel oil purifier. The data collection method used in this study is the observation method and discussion method with the crew or employees of PT. Kayu Lapis Indonesia as the ship owner, and literature study methods. This research uses a qualitative analysis method, namely by directly analyzing the problems in the fuel oil purifier. The research results concluded that the cause of overflow in the fuel oil purifier was due to a dirty bowl caused by a lack of cleaning and maintenance of the Main Cylinder, damage or wear to the Main Seal Ring and a dead end of the nozzle. The efforts made to overcome overflow in the fuel oil purifier are by blowing up manually, carrying out cleaning (overhaul) of the purifier bowl and walls, checking the fuel pressure entering the FO purifier, setting the temperature on the fuel heater, installing Play the Seal Ring correctly, maintain the nozzle and maintain the HFO purifier by the PMS & Instruction manual book.

Electrical conductivity based algorithm for precise application of liquid nitrogenous fertilizers

Precise application of nitrogenous fertilizers mainly urea ammonium nitrate (UAN) and granular urea (both pure and neem-coated) in aqueous form, is critically important for basal and foliar applications. The physicochemical properties of aqueous solution of these nitrogenous fertilizers plays important role in design of any liquid fertilizer application system. The study was carried out during 2019–20 at ICAR-Indian Agricultural Research Institute, New Delhi with an aim to develop algorithms for use in sensors-based systems for real time monitoring of available N concentration in the fertilizer solution before its application. The physicochemical properties like pH, electrical conductivity (EC), specific gravity (SG), dynamic viscosity (DV), surface tension (ST) and percentage light absorbance (LA) of urea ammonium nitrate (UAN-28%), pure urea, and neem coated urea in diluted form (pre-selected N-concentrations i.e. 0.78, 0.9, 1.08, 1.33, 1.75, 2.54 and 4.67% corresponding to the dilution ratios of 1:35, 1:30, 1:25, 1:20, 1:15, 1:10 and 1:05) were measured and analyzed for their significance with N-concentration. Electrical conductivity (EC) alone showed a significant relationship with N-concentrations. Prediction models were developed for diluted UAN and granular urea fertilizers based on the EC and N-concentrations. The regression models in terms of EC to predict N-concentration had coefficients of determination (R2) of 0.998, 0.998, and 0.999 for diluted UAN, pure urea, and neem coated urea with water, respectively showed a great potential for their sensor based precise application. The controlled application of diluted liquid fertilizers with water can be achieved through sensing relevant physicochemical property.

Regulation of Electron Delocalization Region in 2D Heteroligand-Based Copper-Organic Framework to Enhance Charge Storage.

The rechargeable aqueous ammonium ion battery shows great potential in low-cost energy storage system because of its long life and environmental friendliness. However, most inorganic host materials used in ammonium ion batteries are still limited by slow diffusion kinetics. Herein, it is identified that a 2D heteroligand-based copper-organic framework featuring numerous ammonium ion adsorption site in the π-conjugated periodic skeleton supplies multiple accessible redox-active sites for high-performance ammonium storage. Benefitting from the effective regulation of electron delocalization by heteroligand and the inherent hydrogen bond cage mechanism between ammonium ions, the resultant full battery delivers a large specific energy density of 211.84Whkg-1, and it can be stably operated for 12000 cycles at 5Ag-1 for over 80 days. This explanatory understanding provides a new idea for the rational design of high-performance MOF-based ammonium ion battery cathode materials for efficient energy storage and conversion in the future.

In situ, fast constructing interface/doping-engineered NiCo bimetal-based composites boosting electrocatalytic oxygen reduction for zinc-air battery

Investigating cost-effective, high-performance, stable and durable oxygen reduction reaction (ORR) catalysts is imperative, yet it’s still a formidable obstacle in the advancement of metal-air batteries. In this research, NiCo-bimetallic oxides in situ combined with NiCo-bimetal alloy upon the surface of carbon-based matrix (reduced graphene oxide) (NiCo/Co-NiO/rGO) were synthesized by microwave hydrothermal treatment coupled with an ultrafast Joule heating shock process. The interfacial charge transfer between the bimetal alloy and metal oxide in NiCo/Co-NiO/rGO resulted in electron redistribution at the heterointerface, where *O species migrated to the NiCo alloy surface through Mn+-O-M0 (M=Ni, Co and n=2, 3) bonds, facilitating continuous electron transport between the two phases and unveiling added active sites. Introducing abundant oxygen vacancies by Ni3+ and Co3+ facilitated charge transfer between different valence states and led to forming more active sites, thus significantly enhancing ORR performance. More importantly, solid solution strengthening within the NiCo-bimetallic alloy mitigated the oxidation and corrosion of the catalyst. Therefore, the as-synthesized NiCo/Co-NiO/rGO(5 % Co) exhibited excellent ORR performance under an alkaline medium. It achieved a half-wave potential(E1/2) of 0.85 V(vs. RHE) and maintained 89.10 % of its current density after a 12-h long-term reaction. The assembled zinc-air battery (ZAB) employing this catalyst proved remarkable specific capacity (807.04 mAh·gZn−1), power density (95.54 mW cm−2) and cycling stability (over 240 h), outperforming that of commercial Pt/C+RuO2-based ZAB device. This study presents a viable approach for fabricating low-cost dual transition metal-based catalysts, thereby boosting their electrocatalytic performance and enhancing the efficiency and longevity of metal-air batteries.

Growth and biomass of Wolffia arrhiza with different sources of organic fertilizer

Wolffia arrhiza has a growth rate and biomass as well as a good nutritional content for the growth of cultivated fish, especially herbivorous fish. Due to the high protein content (up to 45% of the dry weight), Wolffia is an excellent plant for the production of various biologically active substances, especially proteins. These plants can double every 1-6 days, similar to algae or mushrooms, and the number of leaves doubles every 2-3 days. This study aims to determine the effect of different fertilizer sources on doubling time, relative growth rate, population density and biomass of Wolffia arrhiza and water quality. The method used in this research is experimental. The research design used a completely randomized design (CRD) consisting of 4 treatments and 3 replications. The treatments were as follows: treatment A: chicken manure, B: cow manure, C: buffalo manure and D: goat manure with each dose of 200 grams. Parameters observed included doubling time, relative growth rate, population density, biomass and water quality parameters. The results showed that treatment B (cow manure) gave the highest value for doubling time, 1.59 days, relative growth rate 0.392 g/day, population density 209.75 ind/cm2, biomass 94.97. Keyword: Biomass; Fertilizer; Growth; Wolffia

Research Progress on Physiological, Biochemical, and Molecular Mechanisms of Potato in Response to Drought and High Temperature

With the intensifying global warming trend, extreme heat and drought are becoming more frequent, seriously impacting potato yield and quality. To maintain sustainable potato production, it is necessary to breed new potato varieties that are adaptable to environmental changes and tolerant to adversity. Despite its importance, there is a significant gap in research focused on the potential mechanisms of potato resistance to abiotic stresses like drought and high temperatures. This article provides a comprehensive review of the recent research available in academic databases according to subject keywords about potato drought tolerance and high temperature tolerance with a view to providing an important theoretical basis for the study of potato stress mechanism and the selection and breeding of potato varieties with drought and high-temperature resistance. The suitable relative soil moisture content for potato growth and development is 55% to 85%, and the suitable temperature is 15 °C to 25 °C. The growth and development of potato plants under drought and high-temperature stress conditions are inhibited, and plant morphology is altered, which affects the process of potato stolon formation, tuberization and expansion, ultimately leading to a significant reduction in potato tuber yields and a remarkable degradation of the market grade of tubers, the specific gravity of tubers, and the processing quality of tubers. In addition, stress also adversely affects potato physiological and biochemical characteristics, such as reduction in root diameter and leaf area, decrease in net photosynthetic rate of leaves, production of reactive oxygen species (ROS), and increase in membrane lipid peroxidation. In addition, various types of genes and transcription factors are involved in the response to drought and heat at the molecular level in potato. This paper illustrates the effects of stress on potato growth and development and the molecular mechanisms of potato response to adversity in detail, which is intended to reduce the damage caused by drought and high temperature to potato in the context of global warming and frequent occurrence of extreme weather to ensure potato yield and quality and to further safeguard food security.

Study on Microstructure and High-Temperature Mechanical Properties of Al-Mg-Sc-Zr Alloy Processed by LPBF

Al-Mg-Sc-Zr alloy processed via laser powder bed fusion (LPBF) is poised for significant application in aerospace, where its high-temperature capabilities are paramount for the safety and longevity of engineered structures. This study offers a systematic examination of the alloy’s high-temperature tensile properties in relation to its microstructure and precipitate phases, utilizing experimental approaches. The LPBF-processed Al-Mg-Sc-Zr alloy features a bimodal microstructure, with columnar grains in the melt pool’s interior and equiaxed grains along its boundary, conferring exceptional properties. The application of well-calibrated processing parameters has yielded an alloy with an impressive relative density of 99.8%, nearly fully dense. Following a thermal treatment of 350 °C for 4 h, the specimens were subjected to tensile tests at both room and elevated temperatures. The data reveal that the specimens exhibit a tensile strength of 560.6 MPa and an elongation of 11.1% at room temperature. A predictable decline in tensile strength with rising temperature is observed: at 100 °C, 150 °C, 200 °C, and 250 °C; the respective strengths and elongations are 435.1 MPa and 25.8%, 269.4 MPa and 20.1%, 102.8 MPa and 47.9%, 54.0 MPa and 72.2%. These findings underpin the technical rationale for employing LPBF-processed Al-Mg-Sc-Zr alloy in aerospace applications.

Multispecies macrozoobenthic seasonal bioturbation effect on sediment erodibility

Bioturbation in estuarine environments describes all sediment reworking processes implied in sediment transport. However, modelling at large spatial and temporal scales remains a challenge because of the need to consider the fauna at the community level, and because animal behaviour is highly seasonal with non-linear effects of macrofauna functional trait interactions. Bioturbation processes can be linked to the activity of organisms, based on the principle of energy ecology, linking the metabolic rate to the erodibility of a sediment colonised by benthic fauna. This study investigates this postulate by evaluating the erodibility parameters of a sediment subjected to: i) the bioturbation under seasonal temperature variations; ii) the synergistic bioturbation of different species. The experimental design consisted of: i) three temperature levels (winter, spring and summer), ii) three types of species duos (Cerastoderma edule and Macoma balthica; Scrobicularia plana and Hediste diversicolor; Corophium volutator and Peringia ulvae) at 4 different relative densities. Two successive experiments were carried out on the same individuals: measurement of oxygen consumption of fauna then measurement of the erodibility of the colonised sediment in a flume. The oxygen consumption confirmed that the metabolic rate is a good model of the fauna respiration, regardless of species. The erosion results indicated that the metabolic rate in the case of the fluff layer resuspension is an interesting descriptor for 1) the assessment of the bioturbation under variable temperatures and 2) the integration of the two different bioturbator species that could co-occur in the same habitat. In contrast, the effect of bioturbation on the mass sediment erosion threshold cannot be easily modelled by using the metabolic rate and the classification in functional groups is required. Bioturbation models of the fluff layer using metabolic rate is a promising tool for modelling the effects of faunal communities on sediment transport at the scale of an estuary and over the long term, even projected in the context of global warming.

Maintenance intravenous fluid therapy in infants with sepsis and hyponatremia: a clinical trial

BackgroundThis study aimed to compare the effect of two methods of maintenance intravenous fluid therapy on hyponatremia in hospitalized infants with sepsis.MethodsIn a double-blinded randomized clinical trial, 60 term infants with sepsis were enrolled. Blood samples were taken to determine sodium, potassium, Creatinine, and BUN levels before the initiation of treatment. Urine samples were taken to assess specific gravity and urinary output. Infants in the intervention group received half saline in 10% dextrose and infants in the control group were assigned to receive the conventional solution as maintenance. The above indicators were re-evaluated 24 and 48 h after the initiation of treatment. Two groups were compared concerning the incidence of hyponatremia, and other criteria such as urinary output and urinary specific gravity, blood urea nitrogen (BUN), and creatinine levels.ResultsHyponatremia was more common in the control group. Sodium levels were significantly higher in half saline recipients 24 h (137.83 ± 2.86 vs. 134.37 ± 1.91 mmol/L), and 48 h (138.10 ± 2.41 vs. 133.66 ± 1.98 mmol/L) after treatment (P < 0.001). Although BUN in the intervention group was significantly higher in comparison to the control group, the difference in urinary output, urine specific gravity, potassium, and Creatinine levels were not significant in the two groups.ConclusionsThe use of a half-saline solution as maintenance fluid reduces the risk of hyponatremia after 48 h when compared to 0.18%NaCl.Trial registrationThis has been registered at Iranian Registry of Clinical Trials (Retrospectively registered, Registration date: 2017-10-12, identifier: IRCT2017053034223N1, https://irct.behdasht.gov.ir/trial/26204).

A relativistic scalar model for fractional interaction between dark matter and gravity

Abstract In a series of recent papers we put forward a “fractional gravity”&amp;#xD;framework striking an intermediate course between a modified gravity theory and an&amp;#xD;exotic dark matter (DM) scenario, which envisages the DM component in virialized&amp;#xD;halos to feel a non-local interaction mediated by gravity. The remarkable success&amp;#xD;of this model in reproducing several aspects of DM phenomenology motivates us to&amp;#xD;look for a general relativistic extension. Specifically, we propose a theory, dubbed&amp;#xD;Relativistic Scalar Fractional Gravity or RSFG, in which the trace of the DM stressenergy tensor couples to the scalar curvature via a non-local operator constructed with&amp;#xD;a fractional power of the d’Alembertian. We derive the field equations starting from&amp;#xD;an action principle, and then we investigate their weak field limit, demonstrating that&amp;#xD;in the Newtonian approximation the fractional gravity setup of our previous works is&amp;#xD;recovered. We compute the first-order post-Newtonian parameter γ and its relation&amp;#xD;with weak lensing, showing that although in RSFG the former deviates from its GR&amp;#xD;values of unity, the latter is unaffected. We also perform a standard scalar-vectortensor-decomposition of RSFG in the weak field limit, to highlight that gravitational&amp;#xD;waves propagate at the speed of light, though also an additional scalar mode becomes&amp;#xD;dynamical. Finally, we derive the modified conservation laws of the DM stress energy&amp;#xD;tensor in RSFG, showing that a new non-local force emerges, and hence that the DM&amp;#xD;fluid deviates from the geodesic solutions of the field equations.

Evolution of relative density and shear wave velocity in non-compacted embankment layers: Geological long-term monitoring

This study proposes a novel method for assessing the evolution of relative density and shear wave velocity that vary with depth and effective stress in non-compacted embankment layers. Embedded soil stiffness measurement devices were used to monitor the shear waves at each stage of filling at the test site, and comprehensive laboratory compaction tests were conducted using a floating ring oedometer cell to reproduce real field conditions with minimal friction. Assuming a constant soil unit weight γ with 7% water content, the effective stress σ’ is proportional to depth z (i.e., σ’ = γ·z). Field test results were compared with the shear wave velocity relationships determined in laboratory tests for four samples of differing relative density (30%, 50%, 70%, and 90%), indicating that the relative density at the bottom of the embankment varied between 15% and 48%. However, the constant soil unit weight applied in this study can underestimate the relative density of the embankment, causing a prediction error if the self-weight compaction of the embankment is not minute. Therefore, this study provides guidelines based on a physics-inspired and data-based approach and anticipates the relative density and shear wave velocity analyzed in the context of depth in non-compacted embankment layers. The physics-based data analyses suggested in this study can be used in first-order estimations to assess the relative density and shear wave velocity evolution in non-compacted embankment layers.

Fabrication of Boron Carbide Ceramics Reinforced with Silicon Carbide Fibers

In the present study, the boron carbide ceramics reinforced with silicon carbide fibers (B4C-SiCf) were fabricated by incorporating various contents of SiCf ranging from 2.5 to 10 wt.%. The B4C-SiCf powder mixtures were sintered using the Field Assisted Sintering Technique (FAST), also known as Spark Plasma Sintering (SPS), at temperatures of 1800 °C and 2000 °C for 5 min by applying a pressure of 70 MPa in argon atmosphere, while heating and cooling rates were maintained at 100 °C/min and 50 °C/min, respectively. The influence of the initial powder ratio on the sintering behavior, relative density, microstructural development, and mechanical properties of the obtained B4C-SiCf composites was investigated. The results indicated that the sintered ceramic materials contained only the initial compounds, i.e. B4C and SiC phases. Scanning Electron Microscopy (SEM) showed that the sintered composites consisted of densely compacted B4C grains. The highest relative density (> 99%) was achieved for the sample with 95 wt.%B4C and 5 wt.%SiCf, sintered at 2000 °C. Depending on the constituent content and the densification temperature the obtained composites demonstrated hardness values ranging from 29 to 43 GPa. The maximal hardness was attained in the composite with 95 wt.%B4C sintered at 2000 °C. To assess the performance of the composites under extreme conditions, the ablation resistance was evaluated using a flowing oxyacetylene torch test. The material containing 5 wt.%SiCf exhibited superior ablation resistance when compared to the other compositions. The attained results of this study showed that the SPS technique is a highly effective method for the densification of additive-free B4C-SiCf ceramic composites, showcasing promising properties for applications in extreme environments.

Evaluation of the machinability and enhancement of biological response of ZTA-based 13-93 bio-glass composite materials

Besides the exceptional mechanical and biocompatible properties, zirconia toughened alumina (ZTA) has limited biomedical applications due to its bio-inertness properties. The present work examines the effect of 13-93 bio-glass (BG) addition on the machinability and biological responses of ZTA-containing BG composites. The ZTA–xBG (x = 0, 5, 10, 15, and 25 wt%) composites have been synthesized and sintered at 1250°C for 4 h. The machining of composite samples is done on an abrasive air-jet machine (AAJM), and their machinability is studied in terms of surface roughness (SR), material removal rate (MRR), and mechanics of material removal (MMR). The result indicates that MRR decreases and SR enhances with the addition of BG. The MMR is studied using machined surface morphology, and the results confirm that material removal is due to the large erosion crater. The relative density is decreased with enhancing the BG content except for a sample containing a high amount of BG (25 wt%). Mechanical properties such as hardness and flexural strength are enhanced by BG content up to 25 wt%. In-vitro analysis in simulated body fluid (SBF) reveals that both corrosion and bioactivity increase as BG concentrations increase. According to the in-vitro cell culture data, adding BG to ZTA improves cellular viability with BG content up to 25 wt%. The antibacterial result shows that the viability of the bacterial cells on the composites has significantly decreased with BG content. As a result, biomaterials with this architecture may be used as bone implants.