Search Results (1,512)

In this study, a thin film of silicon carbide (SiC) was deposited on a porous silicon (P-Si) substrate using pulsed laser deposition (PLD). The photo–electrochemical etching method with an Nd: YAG laser at 1064 nm wavelength and 900 mJ pulse energy and at a vacuum of 10⁻² mbar P-Si was utilized to create a sufficiently high amount of surface area for SiC film deposition to achieve efficient SiC film growth on the P-Si substrate. X-ray diffraction (XRD) analysis was performed on the crystalline structure of SiC and showed high-intensity peaks at the (111) and (220) planes, indicating that the substrate–film interaction is substantial. Surface roughness particle topography was examined via atomic force microscopy (AFM), and a mean diameter equal to 72.83 nm was found. Field emission scanning electron microscopy (FESEM) was used to analyze surface morphology, and the pictures show spherical nanoparticles and a mud-sponge-like shape demonstrating significant nanoscale features. Photoluminescence and UV-Vis spectroscopy were utilized to investigate the optical properties, and two emission peaks were observed for the SiC and P-Si substrates, at 590 nm and 780 nm. The SiC/P-Si heterojunction photodetector exhibited rectification behavior in its dark I–V characteristics, indicating high junction quality. The spectral responsivity of the SiC/P-Si observed a peak responsivity of 0.0096 A/W at 365 nm with detectivity of 24.5 A/W Jones, and external quantum efficiency reached 340%. The response time indicates a rise time of 0.48 s and a fall time of 0.26 s. Repeatability was assured by the tight clustering of the data points, indicating the good reproducibility and stability of the SiC/P-Si deposition process. Linearity at low light levels verifies efficient photocarrier generation and separation, whereas a reverse saturation current at high intensities points to the maximum carrier generation capability of the device. Moreover, Raman spectroscopy and energy dispersive spectroscopy (EDS) analysis confirmed the structural quality and elemental composition of the SiC/P-Si film, further attesting to the uniformity and quality of the material produced. This hybrid material’s improved optoelectronic properties, achieved by combining the stability of SiC with the quantum confinement effects of P-Si, make it useful in advanced optoelectronic applications such as UV-Vis photodetectors. Full article

With the continuous growth of global energy demand, the exploitation of deepwater oil and gas resources has become an important part of national energy strategies. The high-viscosity crude oil in deepwater areas such as the South China Sea poses severe challenges to oil and gas pipeline transportation due to its high pour point and high viscosity characteristics. Wax deposition, particularly significant under low temperature and high viscosity conditions, can lead to reduced pipeline flow rates, decreased transportation efficiency, and even potential safety hazards. Therefore, in-depth research on the wax deposition characteristics and mechanisms in high-viscosity systems holds significant theoretical and engineering application value. Current research primarily focuses on the influencing factors of wax deposition, deposition mechanisms, and the establishment of prediction models. Studies have shown that external factors such as temperature, shear intensity, operating time, and water content have significant effects on the wax deposition process. Specifically, increased temperature differences accelerate the deposition of wax molecules, while the presence of the aqueous phase inhibits wax crystallization and deposition. Furthermore, the formation mechanisms of wax deposition mainly include molecular diffusion, shear stripping, and aging effects. Researchers have explored the dynamic changes and influencing laws of wax deposition by establishing mathematical models combined with experimental data. In summary, although some progress has been made in studying the wax deposition characteristics in high-viscosity systems, research on wax deposition characteristics in mixtures, especially under the combined action of pour point depressants and flow improvers, is still inadequate. Future research should strengthen the systematic exploration of wax deposition mechanisms, quantify the effects of different external factors, and develop wax deposition prediction models suitable for practical engineering to ensure the safe and stable operation of deepwater oil and gas pipelines. Through in depth theoretical and experimental research, robust technical support can be provided for the efficient development of deepwater oil and gas resources. Full article

This study systematically investigates the heterogeneity of the Chang 6 reservoir in the Wuqi–Dingbian region of the Ordos Basin through integrated petrographic analysis using scanning electron microscopy (SEM), thin-section petrography, and mercury intrusion porosimetry. The results reveal that this feldspathic sandstone reservoir exhibits significant compositional and textural variations controlled by depositional environments. Dingbian samples displayed elevated feldspar (avg. 42.3%), lithic fragments (18.1%), and carbonate cementation (15.7%), accompanied by intense mechanical compaction and cementation processes. Pore systems in Dingbian were dominated by residual intergranular pores (58–62% of total porosity) and secondary dissolution pores. In contrast, Wuqi reservoirs demonstrated superior pore connectivity through well-developed intergranular pores (65–72%), grain boundary pores, and microfracture networks. Pore throat characterization revealed distinct architectural patterns: Wuqi exhibited broad bimodal/multimodal distributions (0.1–50 μm) with 35–40% macro-throat (>10 μm) contribution to flow capacity, while Dingbian showed narrow unimodal distributions (1–10 μm) with <15% macro-throat participation. These microstructural divergences fundamentally governed contrasting production behaviors. Wuqi wells achieved higher initial flow rates (15–20 m³/d) with 60–70% water cut, yet maintained stable production through effective displacement systems enabled by dominant macropores. Conversely, Dingbian wells produced lower yields (5–8 m³/d) with 75–85% water cut, experiencing rapid 30–40% initial declines that transitioned to prolonged low-rate production phases. This petrophysical framework provides critical insights for optimized development strategies in heterogeneous tight sandstone reservoirs, particularly regarding water management and enhanced oil recovery potential. Full article

The production of hydrocarbon-based biofuels has been the target of intense research worldwide. In this context, the core goal of the present work was to investigate the use of mesopore-rich activated carbons (ACs) as support for sulfided Mo-based catalysts intended for the hydroprocessing of lipidic feedstocks. The key motivations for the work were that, in comparison to traditional inorganic supports such as Al₂O₃, ACs are less propense to form coke, due to their lower acidity, and are highly resistant to hydrolysis, which is a very important aspect in the hydroprocessing of lipidic feedstocks because water is abundantly produced during the process. Furthermore, the porosity of ACs can be tailored to give rise to a high mesopore content, which is important for improving the access of bulky triglyceride molecules to metallic active sites located inside the pores network. A systematic study on the effects of the preparation conditions on the properties and performance of the obtained catalysts was carried out for the first time. The highest hydrodeoxygenation (HDO) activity was verified for the catalyst prepared through sequential deposition of Mo and Ni by wet impregnation. The prepared catalyst presented better performance for coconut oil HDO than an industrial sulfided NiMo/Al₂O₃ catalyst. Furthermore, it presented good stability, provided that the sulfidation degree was kept high. The obtained results evidenced that ACs have great potential to replace inorganic support in sulfided Mo-based catalysts. Full article

Sediment erosion in turbine components presents a major challenge to the reliable operation of pumped storage power plants, particularly in sediment-laden rivers. While extensive research has been conducted on hydraulic machinery erosion, studies focusing on the combined effects of sediment particle size and concentration on erosion within the runner region of pump turbines remain limited. To bridge this gap, this study investigates the influence of sediment characteristics on erosion patterns and deposition mechanisms in pump-turbine runners through a combination of numerical simulations and experimental validation. The results demonstrate that sediment concentration primarily governs the overall erosion intensity, while particle size significantly influences the spatial distribution of erosion zones. Higher sediment concentrations lead to intensified surface wear and broader erosion regions, whereas larger particles cause localized shifts in erosion-prone areas across different blade surfaces. Furthermore, a strong correlation is identified between erosion zones and sediment accretion regions, highlighting the interplay between material loss and deposition dynamics. By accurately predicting erosion trends, numerical simulations minimize the reliance on costly and time-consuming physical experiments, offering valuable insights for turbine optimization. This study enhances the understanding of sediment-induced erosion mechanisms in pump turbines and provides guidance for improving turbine design and operational strategies in sediment-laden environments. Full article

Background/Objectives: Dry powder inhalation is an attractive research area for development. Therefore, this work aimed to develop inhalable co-spray-dried theophylline (TN) microparticles, utilizing raffinose-amino acid fine carriers intended for asthma therapy. The study addressed enhancing TN’s physicochemical and aerodynamic properties to ensure efficient lung deposition. Methods: The process involves spray-drying each formulation’s solution using a mini spray drier. A rigorous assessment was conducted on particle size distribution, structural and thermal analysis, morphology study, in vitro and in silico aerodynamic investigation, and aerodynamic particle counter in addition to the solubility, in vitro dissolution, and diffusion of TN. Results: The carriers containing leucine and glycine revealed superior characteristics (mass median aerodynamic diameter (MMAD): 4.6–5 µm, fine particle fraction (FPF): 30.6–35.1%, and amorphous spherical structure) as candidates for further development of TN-DPIs, while arginine was excluded due to intensive aggregation and hygroscopicity, which led to poor aerodynamic performance. TN co-spray-dried samples demonstrated fine micronized particles (D [0.5]: 3.99–5.96 µm) with predominantly amorphous structure (crystallinity index: 24.1–45.2%) and significant solubility enhancement (~19-fold). Formulations containing leucine and leucine-glycine revealed the highest FPF (45.7–47.8%) and in silico lung deposition (39.3–40.1%), rapid in vitro drug release (~100% within 10 min), and improved in vitro diffusion (2.29–2.43-fold), respectively. Moreover, the aerodynamic counter confirmed the development of fine microparticles (mean number particle size = 2.3–2.02 µm). Conclusions: This innovative formulation possesses enhanced physicochemical, morphological, and aerodynamic characteristics of low-dose TN for local asthma treatment and could be applied as a promising carrier for dry powder inhaler development. Full article

Flood frequencies, along with the associated loss of life and property, have risen significantly due to climate change and increasing human activities. While prior research has primarily focused on high-intensity rainfall events and reservoir management in flood management, the influence of sediment-starved water—termed “hungry water”—released from dams in controlling flood dynamics has not gained much attention. The present study is aimed at exploring the potential role of sediment-starved water, or the “hungry water effect” on the valley degradation, bed material changes and flood inundation in the Pamba River during the Kerala Flood, 2018, through a detailed characterization of bed materials and their deposition in the channel bed. The release of sediment-starved water from the Kakki reservoir during the episodic precipitation event (15 to 17 August 2018) resulted in significant bed degradation and scouring of the valley slopes, leading to the deposition of large boulders and rock masses and the inundating of approximately 196 km² of floodplains. This study highlights the need for integrated sediment management strategies in reservoir operations by providing essential insights into sediment transport dynamics during extreme weather events. Understanding these processes is crucial for formulating effective flood mitigation strategies and improving the resilience of riverine ecosystems, particularly as the interaction between intense rainfall and sediment-depleted releases significantly exacerbated the flood’s severity. Full article

The interglacial period of the Cryogenian glaciation is a pivotal interval in geological history, marked by two “Snowball Earth” events and the emergence of early animals. Currently, there is considerable debate regarding the paleo-oceanic environment and the dominant factors controlling organic matter enrichment. Here, based on inorganic geochemical data and mineral composition from the Datangpo Formation in Xiangtan (South China), combined with previous research, we have analyzed the paleo-climate, redox condition, seawater restriction, and primary productivity across different sedimentary facies during this critical interval. The results exhibit that the Datangpo Formation can be divided into three members (Da1–Da3) based on lithology. Paleoclimatic proxies suggest the environment was relatively cold during the deposition of the Da-1 Member, while it was relatively warm and humid during the deposition of the Da 2–3 members. Compared to shallow water areas, deep-water areas experienced a more rapid transition in paleotemperature following the Sturtian glaciation event. Combining Mo-U elements, Ce_N/Ce*_N, and C_org/P ratios, the environment was characterized by an oxic environment during the early deposition period of the Datangpo Formation, then gradually transitioned to suboxic, and finally anoxic conditions. Furthermore, the decompression of terrestrial magma chambers led to intense volcanic/hydrothermal activity during the deglaciation period. Hydrothermal activity was most intense during the Da-1 depositional period, followed by Da-2, and gradually declined during Da-3 depositional period. Hydrothermal activity not only provided essential materials for the formation of Mn carbonate ores but also significantly enhanced the primary productivity by introducing large amounts of nutrients in the paleo-ocean. The primary productivity indicators (Ni/Al, Cu/Al) exhibited an obvious coupling with Ce_N/Ce*_N and C_org/P ratios in the Datangpo Formation, indicating that oxygen-rich environments were favorable for biological proliferation, thereby providing abundant organic matter. Anoxic conditions further facilitated the preservation of organic matter, which may be the primary factor driving organic matter enrichment in the Datangpo Formation. Full article

Heavy metals represent a class of pollutants detected at concentrations lower than 10 ppm in different matrices that are intensively monitored due to having a major impact on human health. Industrial activities including mining, agriculture, and transport, determine their presence in different environments. Corrosion phenomena of various installations, volcanic eruptions, or atmospheric deposition on the soil surface and in water can contaminate the respective environments. Atmospheric pollutants in the form of suspended dust particles with diameters below 10 microns are predominantly composed of different metallic species from Cd, Cr, Cu, Ni, etc. This paper presents a review of the main sources and types of heavy metals present in the atmosphere in the composition of particulate matter (PM), highlighting the main mechanisms of occurrence and detection techniques, including the impact on bio-geo-chemical processes in the soil and food chain, in close correlation with their impact on environment and human health. The purpose of this review is to highlight the current level of knowledge regarding the global situation of heavy metals in PM and to identify gaps as targets for future research. Full article

Transport and vehicle traffic are closely connected with particulate matter (PM) pollution, inducing various fractions into the atmosphere, some of them forming significant deposits on the surface of the car. They are washed away during carwash-inducing slurries collecting the PM deposits, which are characteristic of a large area. Crystalline PM matter was investigated by XRD coupled with polarized optical microscopy (POM). Organic matters were investigated by Fourier-Transform Infrared spectrometry (FTIR) and gas chromatography, GC-MS. Their microstructure and elemental composition were investigated by SEM-EDX. The crystalline features contain mainly quartz, calcite, and clay (muscovite and kaolinite) particles having traces of goethite and lepidocrocite. Slurry particle size distribution was established by sieving on the following meshes: 63 µm, 125 µm, 250 µm, 500 µm, 1000 µm, 2000 µm, and 4000 µm. Coarse fractions of 250–4000 μm are dominated by quartz and calcite particles. The quartz and calcite amount decreases with particle size, while the muscovite and kaolinite amount increases in the finest fractions of 0–125 μm. Organic matter was evidenced, firstly, by FTIR spectroscopy, revealing mostly CH₂; C=O, and NH₄ bonds that are more intense for the fine particulate fractions. The organic deposits form mainly amorphous crusts associated with micro- and nano-plastic particles related to the phthalates and traces of the washing detergents. Atomic Force Microscopy revealed their size range between 60 and 90 nm and evidenced nanoparticles within samples. The nanofractions adhere to the bigger particles in humid environments, assuring their immobilization to reduce their hazardous potential. Carwash slurry blending with fertile soil ensures proper grass seed germination and growth at mixtures of up to 60% slurry, allowing its sustainable reconversion as soil for landfill and dump rehabilitation, preventing the PM emission hazard. Blended compositions containing more than 60% slurry have noxious effects on the grass seeds, inhibiting their germination. Full article

In this study, silver nanoparticles (Ag NPs) were synthesized on the surface of rutile-phase titanium dioxide (R-TiO₂) using a plasma-assisted technique. Comprehensive analyses were conducted to investigate the structural, morphological, optical, and electrical properties of the synthesized nanocomposites. Transmission electron microscopy (TEM) images revealed the uniform decoration of Ag NPs (average size: 29.8 nm) on the R-TiO₂ surface. X-ray diffraction (XRD) confirmed the polycrystalline nature of the samples, with decreased diffraction peak intensity indicating reduced crystallinity due to Ag decoration. The Williamson–Hall analysis showed increased crystallite size and reduced tensile strain, suggesting grain growth and stress relief. Raman spectroscopy revealed quenching and broadening of R-TiO₂ vibrational modes, likely due to increased oxygen vacancies. X-ray photoelectron spectroscopy (XPS) confirmed successful plasma-assisted deposition and the coexistence of Ag⁰ and Ag⁺ states, enhancing surface reactivity. UV-Vis spectroscopy demonstrated enhanced light absorption across the spectral range, attributed to localized surface plasmon resonance (LSPR), and a reduced optical bandgap. Dielectric properties, including dielectric constants, loss factor, and AC conductivity, were evaluated across frequencies (4–8 MHz) and temperatures (20–240 °C). The AC conductivity results indicated correlated barrier hopping (CBH) and overlapping large polaron tunneling (OLPT) as the primary conduction mechanisms. Composition-dependent dielectric behavior was interpreted through the Coulomb blockade effect. These findings suggest the potential of plasma assisted Ag NP-decorated R-TiO₂ nanostructures for photocatalysis, sensor and specific electro electrochemical systems applications. Full article

The formation and distribution of sedimentary facies of the Wufeng Formation reflect the evolution of Guangxi Movement and significantly impact shale reservoir quality in southern Sichuan Basin, China. This study characterizes the sedimentary facies and their evolution of Ordovician-Silurian transition shale based on detailed core descriptions, full-scale imaging of large slabs, and field emission scanning electron microscopy of argon-ion polished sections. There only exist fine-grained turbidite deposits, hemipelagic deposits, and shallow shoal deposits for the Wufeng shale. Fine-grained turbidite deposits consist primarily of clastic quartz and clay minerals and can be divided into nine subdivisions. Hemipelagic deposits are mainly composed of quartz, detrital carbonate, and clay minerals. Shallow shoal deposits are dominated by clay minerals, dolomite, and calcite, with carbonates primarily of autochthonous origin. The fine-grained turbidite deposits predominantly occur within the Dicellograptus complanatus and D. complexus graptolite biozones, while hemipelagic deposits are confined to the Paraorthograptus pacificus biozone, and shallow shoal deposits are restricted to the Metabolograptus extraordinarius biozone. Formation and distribution of the three sedimentary facies are closely related to the Guangxi Movement. During the strong tectonic compression stage, sufficient sediment supply and intensive volcanic eruption favored the formation of the fine-grained turbidite deposits. Along with waning tectonic activity and reduced terrestrial input, hemipelagic deposits formed and then shallow shoal deposits. Sedimentary facies exert first-order controls on shale reservoir quality, with hemipelagic deposits exhibiting optimal reservoir characteristics. Laboratory analyses reveal that hemipelagic facies possess the highest porosity (3.34–4.15%) and TOC content (2.91–4.10%) due to biogenic quartz enrichment and minimal allochthonous dilution, whereas fine-grained turbidites show degraded properties (porosity: 1.58–3.81%; TOC: 0.15–2.6%) from high-energy siliciclastic influx. Shallow shoal deposits display intermediate values (porosity: 3.92%; TOC: 3.25%), constrained by carbonate cementation. Full article

Background: Lipedema is an adipose tissue disorder in women, with an abnormal fat deposition in lower limbs and occasionally upper limbs. The condition is characterized by pain, bruising, heaviness, and mobility impairment. Objectives: This study aims to evaluate the effects of a modified Complete Decongestive Therapy protocol using the Godoy Method in the postoperative period following lipedema surgery. Methods: In total, 293 participants who underwent liposuction for lipedema were studied. The postoperative physiotherapy protocol included Godoy cervical stimuli, Manual Lymphatic Drainage based on Godoy maneuvers, mechanical lymphatic drainage with RAGodoy^®, compression with bandages, skin care, and therapeutic education. Results: This study found that the number of physiotherapy sessions significantly reduced pain (p = 0.000) and other complications (p = 0.007) and increased mobility (p = 0.003). The number of physiotherapy sessions showed significant differences in pain intensity at 90 days post-treatment (p = 0.000). In total, 47.24% of the participants became functionally independent on the third day of the physiotherapy intervention (p = 0.003). A total of 40.96% of the participants developed some complications, although a relationship between inadequate compression and the occurrence of complications was also found in 36.52% of patients. Conclusions: The success of surgical treatment for lipedema not only depends on the surgery itself but also on the proper management of the patient in the perioperative period to minimize complications and prevent recurrence. The Complete Decongestive Therapy protocol modified with the Godoy Method showed effects on pain reduction, mobility increase, edema reabsorption, and prevention of complications, consequently enhancing functionality and quality of life for patients undergoing lipedema surgery. Full article

Developing aramid fiber (AF) with electromagnetic interference (EMI) shielding properties is of significant importance for expanding their applications in the military, aerospace, and industrial sectors. Current research on the EMI shielding properties of AF often encounters challenges such as structural damage to the fibers and inadequate shielding performance. In this study, we used vacuum-assisted filtration technology to sequentially deposit aramid nanofiber (ANF) and MXene onto the surface of AF fabric, thus preparing ANF/MXene/AF composite fabric. MXene, with its large specific surface area and excellent electrical conductivity, was used in conjunction with ANF, which acts as an intermediate layer to effectively filter MXene and improve the interfacial adhesion between the MXene and AF. The results showed that, under the combined effects of reflection and absorption, the A20M40 sample achieved an average EMI SE of 78.1 dB in the X-band, meeting the EMI shielding requirements for both civilian and military applications. Additionally, the ANF/MXene/AF composite fabric exhibited excellent electrothermal conversion performance (surface temperature reached 120 °C within 32 s under 5 V) and photothermal performance (surface temperature reached 85 °C after 145 s of exposure to 1500 W/m² light intensity). Furthermore, the flame-retardant performance of the ANF/MXene/AF composite fabric was significantly enhanced compared to the pure AF fabric due to the physical barrier effect of MXene. Full article

Diamond, widely used in optoelectronic devices, plays a crucial role in improving performance through studies of its electronic structure and optoelectronic response. This study combines computational methods and experiments for analysis. Density functional theory calculates the diamond’s band structure and refractive index, while the Keldysh formula determines the laser intensity at the critical plasma density by evaluating laser-induced free electron density. By integrating the coupled model with a multi-physics field associative assignment, the critical plasma length in the diamond is further simulated. Experimentally, pump-probe techniques examine the diamond’s response under varying pulse widths and energies. Results show that increasing laser energy extends both plasma and damage lengths. As pulse width increases, plasma length first decreases and then increases, while graphitization length shows the opposite trend. Experiments show that laser energy enhancement significantly expands the plasma morphology by enhancing the nonlinear ionization effect. When the pulse width exceeds the electron-lattice relaxation time, the lattice energy deposition triggers localized graphitization, which enhances the subsequent laser absorption, and the final plasma distribution shows a high spatial correlation with the graphitized regions. Full article