Low Permeability Research Articles

High-resolution isochronous stratigraphic framework through well-seismic integration in tight sandstone: a case study of Luodai gas field, Sichuan, China

Tight gas sandstone represents a significant unconventional resource extensively discovered across numerous sedimentary basins around the world. Tight sandstone reservoirs are characterized by low porosity, low permeability, variable source material, rapid spatial and temporal changes, poor reservoir properties, and strong heterogeneity. Traditional geophysical methods struggle to meet the demands of exploration and development of these types of reservoirs. This study applies a high-precision comparative approach using well-seismic integration to establish a relative isochronous stratigraphic framework. Based on this framework, extracting seismic properties can effectively predict tight sandstone reservoirs. This paper, focusing on the Penglaizhen Formation in the Luodai Gas Field of the Western Sichuan Jurassic system. This entire process accomplished in three steps: starting with regional marker layers as the initial framework; followed by the establishment of a relative isochronous framework through precise well-seismic integration; and finally stratigraphic slicing techniques to delineate isochronous stratigraphic framework with shorter time intervals. Thereby enhancing the reliability of subsurface stratigraphic information and data accuracy. The study posits that current technological means cannot create a truly isochronous stratigraphic framework; thus, “isochronous” is considered a relative concept in this context. The framework aims to ensure temporal consistency by minimizing discrepancies through mutual constraints between well and seismic data, serving to exploration and development requirements. Furthermore, analyses such as sensitive attribute extraction, impedance inversion, and assessment of hydrocarbon potential in tight sandstone reservoirs demonstrate strong correlation with drilling results. This validation underscores the framework’s efficacy in interpreting industrial gas production flows, thereby providing robust support for future oil and gas exploration.

In-plane dynamic analysis of supershear rupture transition due to poroelastic pressurization

Summary Although pore fluid has received increased attention in the problems of earthquake rupture, its effects on coseismic rupture are not fully understood. In this paper, we numerically simulate dynamic rupture in saturated poroelastic media to study the interplay between poroelastic pressurization and rupture evolution. Particular attention is paid to the physical process of the supershear transition. The spontaneous rupture is assumed to be governed by slip weakening law and the fault is treated as a leaky interface where pore pressure equilibrium is delayed. Results show that the pore pressure induced by coseismic mechanical deformation can strengthen the fault on the extensional side but weaken the fault on the compressional side. As a result, the poroelastic pressurization on the compressional side can promote the occurrence of the transition to supershear rupture while its strengthening effect on the extensional side can suppress this transition even in the state of high initial shear stress. Meanwhile, it is found that the permeability distribution along the fault plane also affects rupture evolution. Faults with nucleation zones located in low permeability regions are more likely to undergo a supershear rupture.

Development, Analysis, and Determination of Pharmacokinetic Properties of a Solid SMEDDS of Voriconazole for Enhanced Antifungal Therapy

Background: Voriconazole is an antifungal drug, which is classified under Bio-Classification System-II and has low water solubility (0.71 mg/mL) and high permeability. Hardly any endeavors have been made to increase the bioavailability of voriconazole. Objective: To develop and evaluate a solid SMEDDS (self-microemulsifying drug delivery system) for antifungal activity. Methods: Based on solubility studies of Labrafil-M 1994 CS (oil), Cremophor-RH 40 (a surfactant) and Transcutol-HP (a co-surfactant) were selected as components of the SMEDDS and a pseudo-ternary phase diagram was prepared. Thereafter, the oil, surfactant, and co-surfactant were mixed with altered weight ratios (1:1/1:2/2:1) and evaluated through various in vitro, in vivo analyses. Results: The particle size of the optimized formulation was observed to be 19.04 nm and the polydispersity index (PDI) value was found to be 0.162 with steady-state zeta potential. The optimized liquid SMEDDS was converted into a solid SMEDDS. Various adsorbents, such as Aerosil-200, Avicel-PH101, Neusilin-US2, and Neusilin UFL2 were screened to better detect the oil-absorbing capacity and flow properties of the powder. Neusilin UFL2 was selected as an adsorbent due to its better oil-absorbing capacity. DSC, X-ray diffraction, and dissolution studies were carried out to characterize the formulation. Further, the Pharmacokinetic profile was also studied in Wistar rats and the Cmax, tmax, and AUC0®t were calculated. The Cmax and AUC0®t plasma concentration is considerably better for the SMEDDS than for the pure drug and marketed formulation. Conclusions: This investigation clearly reveals the potential of developing a solid SMEDDS for candidiasis and invasive aspergillosis treatment, with better efficacy as compared to the commercially available marketed formulation.

Advances in Aerogels Formulations for Pulmonary Targeted Delivery of Therapeutic Agents: Safety, Efficacy and Regulatory Aspects.

Aerogels are the 3D network of organic, inorganic, composite, layered, or hybrid-type materials that are used to increase the solubility of Class 1 (low solubility and high permeability) and Class 4 (poor solubility and low permeability) molecules. This approach improves systemic drug absorption due to the alveoli's broad surface area, thin epithelial layer, and high vascularization. Local therapies are more effective and have fewer side effects than systemic distribution because inhalation treatment targets the specific location and raises drug concentration in the lungs. The present manuscript aims to explore various aspects of aerogel formulations for pulmonary targeted delivery of active pharmaceutical agents. The manuscript also discusses the safety, efficacy, and regulatory aspects of aerogel formulations. According to projections, the global respiratory drug market is growing 4-6% annually, with short-term development potential. The proliferation of literature on pulmonary medicine delivery, especially in recent years, shows increased interest. Aerogels come in various technologies and compositions, but any aerogel used in a biological system must be constructed of a material that is biocompatible and, ideally, biodegradable. Aerogels are made via "supercritical processing". After many liquid phase iterations using organic solvents, supercritical extraction, and drying are performed. Moreover, the sol-gel polymerization process makes inorganic aerogels from TMOS or TEOS, the less hazardous silane. The resulting aerogels were shown to be mostly loaded with pharmaceutically active chemicals, such as furosemide-sodium, penbutolol-hemisulfate, and methylprednisolone. For biotechnology, pharmaceutical sciences, biosensors, and diagnostics, these aerogels have mostly been researched. Although aerogels are made of many different materials and methods, any aerogel utilized in a biological system needs to be made of a substance that is both biocompatible and, preferably, biodegradable. In conclusion, aerogel-based pulmonary drug delivery systems can be used in biomedicine and non-biomedicine applications for improved sustainability, mechanical properties, biodegradability, and biocompatibility. This covers scaffolds, aerogels, and nanoparticles. Furthermore, biopolymers have been described, including cellulose nanocrystals (CNC) and MXenes. A safety regulatory database is necessary to offer direction on the commercialization potential of aerogelbased formulations. After that, enormous efforts are discovered to be performed to synthesize an effective aerogel, particularly to shorten the drying period, which ultimately modifies the efficacy. As a result, there is an urgent need to enhance the performance going forward.

Enhanced microwave absorption using multiple heterostructures derived from in-situ grown Sn-metal-organic framework on La-doped Fe3O4

As a representative magnetic oxide absorber, Fe3O4 has attracted considerable research attention owing to its remarkable magnetic saturation strength as well as semiconducting properties. Doping Fe3O4 with La3+ leads to 3d-4f magnetic coupling and ion distribution changes due to the unique electron configuration and large ionic radius of La3+, thereby greatly enhancing the magnetic performance. However, high density, low dielectric loss, and low permeability at high frequencies inhibit the electromagnetic wave absorption (EMWA) performance of ferrites. In this study, stick-shaped Sn metal-organic framework (MOF) is in-situ grown on La3+-doped Fe3O4 using a surfactant. After high-temperature annealing, the SnO2/porous carbon composites derived from Sn-MOF wrap the ferrite, forming a core-shell heterostructure, which not only prevents oxidation but also enhances the EMWA performance. Among the prepared LaxFe3-xO4/SnO2/C (LFSC) samples, LFSC-2 (with LaxFe3-xO4 to Sn-MOF ratio of 1:2) exhibits strong absorption performance with a minimum reflection loss (RLmin) of −44.1 dB. Furthermore, the gradient metamaterial based on LFSC-3 shows ultra-broadband EMWA with an effective absorption bandwidth (RLmin ≤ −10 dB) of 13.17 GHz. In addition, the LFSC-2 sample demonstrates excellent radar stealth capability in the radar cross section (RCS) far-field response, achieving an RCS reduction value of 20.4 dB·m2.

Glibenclamide-encapsulated Liposomes alleviate LPS-induced Inflammatory Cascade through NLRP3 inhibition in macrophages

Abstract Inflammation is a vital immune response for survival during infection and tissue damage. It is critical in maintaining normal tissue homeostasis by orchestrating appropriate inflammatory mediators. Macrophages, integral to innate immunity, respond to lipopolysaccharide (LPS) present in gram-negative bacteria by releasing inflammatory cytokines. Utilizing nanotechnology for drug delivery have been proven with enhanced therapeutic approaches by targeting the suppression of inflammatory mediators and cytokines. Recent studies have provided insights into the role of inflammasomes in intracellular processes linked to inflammation. Glibenclamide (GLB), a sulfonylurea used in type 2 diabetes treatment, has emerged as a potent inhibitor of the NLRP3 inflammasome, showing promise in alleviating inflammation-associated injuries. To overcome the limitations of GLB, such as low aqueous solubility and high permeability, in this study, methyl-PEG-DSPE lipids were used to develop GLB-loaded nanoliposomes. The size of blank liposome was measured to be 120 nm. Anionic GLB-loaded liposomes, sized 146 nm with spherical morphology, effectively suppressed the expression of NLRP3 mediators (caspase-1, ASC, IL-1B, and IL-18) and various reactive oxygen species mediators compared to free GLB, reducing LPS-induced inflammatory responses in RAW264.7 macrophages. This suggests the potential of GLB-loaded liposomes as a therapeutic agent for inflammation-related disorders, warranting further in-vivo investigation.

Effectiveness and impact factors of passive convergence-permeable reactive barrier (PC-PRB): Insights from tracer simulation study

Passive convergence-permeable reactive barrier (PC-PRB) represents a green and sustainable technology for in-situ remediation of contaminated groundwater. A laboratory-scale PC-PRB tracer simulation system was established to quantify its contaminant plume capture performance using image analysis method. Results indicate that PC-PRB captures the plume 65% wider than C-PRB, which means that fewer PRB sizes and materials volume would be necessary to treat an equivalent contaminated plume. This improvement is due to a significant drawdown within the PC-PRB's passive well, known as the passive hydraulic decompression-convergent flow effect. We further evaluated the effects of water pipe length, hydraulic gradient, and media particle size on PC-PRB's plume capture performance. Results indicate that an increased water pipe length enhances the PC-PRB's plume capture capacity due to greater well drawdown. PC-PRB not only captures the plume but also acts as a hydraulic barrier. The retardation effect of PC-PRB on plume migration increases with water pipe length. Conversely, both hydraulic gradient and media particle size impact the plume capture capacity of PC-PRB by modifying groundwater flow velocity and pollutant dispersion. An increase in either hydraulic gradient or media particle size decreases the plume capture performance of PC-PRB. Therefore, PC-PRB technology may be more effective in contaminated sites characterized by low hydraulic gradients and permeability. Overall, PC-PRB demonstrates significant effectiveness in enhancing plume capture performance, which can notably reduce remediation costs and environmental footprint, broadening its application scope.

Geometric flow control in lateral flow assays: Macroscopic two-phase modeling

Lateral flow assays (LFAs) are widely employed in a diverse range of applications, including clinical diagnostics, pharmaceutical research, forensics, biotechnology, agriculture, food safety, and environmental analysis. A pivotal component of LFAs is the porous polymeric membrane, which facilitates the capillary-driven movement of fluids, known as “imbibition,” in which a wetting fluid displaces a non-wetting fluid within the pore space of the membrane. This study presents a multi-scale modeling framework designed to investigate the imbibition process within LFAs. The framework integrates microscopic membrane characteristics into a macroscopic two-phase flow model, allowing the simulation of imbibition in membranes with different micro-scale properties and macro-scale profiles. The validity of the model was established through comparative analysis with documented case studies, a macro-scale single-phase flow model, and experimental observations, demonstrating its accuracy in simulating the imbibition process. The study also examines imbibition in various geometric configurations, including bifurcated (Y-shaped) and multi-branch geometries commonly found in multiplexed LFAs. The influence of geometric features such as length ratio, width ratio, branching angle, bifurcation point location, and asymmetry on fluid transport is investigated. Results indicate that membranes with larger branching angles exhibit slower imbibition. In addition, the influence of membrane type on macroscopic flow patterns is evaluated, showing that membranes with lower permeability require longer imbibition times. The insights gained from this research support a data-driven strategy for manipulating wetting behavior within LFAs. This approach can be leveraged to optimize the performance of LFAs and increase their effectiveness in various applications.

Advanced Technologies in Rectal Drug Delivery Systems: A Comprehensive Review of Recent Innovations and Future Prospects

Abstract: Rectal Drug Delivery System (RDDS) emerges as an alternative administration route due to the rectum's small surface area and limited enzyme activity, which contribute to efficient drug absorption. RDDS offers various advantages, such as reduced first-pass metabolism, rapid absorption of low molecular weight drugs, and the ability to accommodate large retention volumes and facilitate absorption via the lymphatic system. Moreover, RDDS is preferable for drugs with low stability, solubility, and permeability via oral administration, as well as effectively addressing concerns related to gastric irritation or degradation. This review delves into the factors influencing drug absorption in RDDS, including drug properties, formulation types, and physiological and pathology-associated considerations. It further explores conventional RDDS, including enemas, suppositories, tablets, gels, sprays, ointments, and creams, as well as novel approaches involving nanoparticles, liposomes, microspheres, and solid lipid nanoparticles (SLNs) in rectal dosage forms. Furthermore, the challenges and prospects of RDDS in treating rectal diseases are discussed. This review provides valuable insights into the potential of RDDS, highlighting the importance of continuous research and development in enhancing patient outcomes and advancing healthcare practices.

Developing Liquefaction Prediction Equations for Gravels Based on DPT Blow Count and Shear Wave Velocity at Field Case History Sites

Gravelly soils have liquefied at multiple sites in at least 20 earthquakes over the past 130 years. These gravels typically contain more than 25% sand which lowers the permeability and makes them susceptible to liquefaction. In other cases, a low permeability layer at the surface impedes drainage and causes liquefaction. Typical SPT- or CPT-based liquefaction correlations can be affected by large gravel particles and lead to erroneous results. To deal with these problems, we have developed liquefaction triggering curves for gravelly soils based on (1) shear wave velocity (Vs) and (2) a 74-mm diameter dynamic cone penetrometer (DPT), that are less affected by gravel particles. These correlations are based on case histories where gravel did and did not liquefy in past earthquakes. The VS-based liquefaction triggering curves for gravels shift to the right relative to similar curves based on sands. Good agreement has been obtained with liquefaction resistance from the DPT and the CPT when these methods could all penetrate the gravel in Wellington New Zealand. Correlations are developed between Vs and blow count from the DPT.

Robotics and artificial intelligence in unconventional reservoirs: Enhancing efficiency and reducing environmental impact.

Shale, tight gas, and coal bed methane reservoirs are unconventional reservoirs that have geometrically complicated geological formations with low permeability, rendering their extraction operations difficult, expensive, and environmentally sensitive. On the other hand, recent developments in Robotics and Artificial Intelligence continue to transform how exploration, production, and maintenance activities are carried out in these reservoirs. This review paper encompasses how Robotics and AI technologies are applied to these unconventional reservoirs, improving operation efficiency, increasing the recovery rate and minimizing environmental damage. It updates on the latest status of autonomous drilling, AI-driven reservoir characterization and robotic fracturing. The paper also discusses future opportunities: emerging technologies, integration of AI with predictive analytics, and innovations toward sustainability. These are the challenges that come with possible solutions discussed in the paper: high costs, technical integration, and data quality. The review thereby presents the thought that robotics and AI will take a transformative role in the unconventional reservoir sector during the next few years, both in economic performance and environmental sustainability.

Experimental study on the dynamic threshold pressure gradient of high water-bearing tight sandstone gas reservoir

Tight sandstone water-bearing gas reservoirs typically exhibit low porosity and low permeability, with reservoir rocks characterized by complex pore structures, often featuring micron-scale or smaller pore throats. This intricate reservoir structure significantly restricts fluid flow within the reservoir, necessitating a certain threshold pressure gradient (TPG) to be overcome before flow can commence. This study focuses on the Ordos Basin and explores the influence of high water content tight sandstone gas reservoirs on TPG under different water saturation and formation pressure conditions through experiments. A mathematical model of TPG is established using multiple linear regression method. The results show that TPG is primarily affected by water saturation, followed by formation pressure. As the water saturation increases, the TPG of the core decreases, and the change becomes more pronounced when the water saturation exceeds 50%. As formation pressure increases, the weakening of the slippage effect in gas molecules leads to TPG stabilization, especially when local pressure exceeds 25.0 MPa. The research also shows that low-permeability cores exhibit greater TPG variation with pressure changes, while high-permeability cores remain more stable. A mathematical model was developed and validated to predict TPG based on permeability, water saturation, and formation pressure. These findings highlight the need to monitor formation water content during tight sandstone gas reservoir development to optimize production strategies, providing valuable insights for improving reservoir management and guiding future research.

Mitigating autogenic shrinkage in high‐performance concrete using wollastonite: A structural enhancement approach

AbstractThis study investigates the influence of wollastonite fiber as a reinforcement in high‐performance concrete (HPC), focusing on its potential to mitigate autogenic shrinkage and enhance overall structural properties. HPC known for its superior strength and low permeability, often suffers from intensified autogenic shrinkage, leading to micro‐cracking and compromising durability. To address this challenge, wollastonite was incorporated at different substitutions (0%, 5%, 10%, and 15%) for both cement and aggregate. The experimental program involved a systematic evaluation of compressive strength, flexural strength, porosity, water absorption, and corrosion resistance with tests conducted at different curing periods. We found that the addition of 10% wollastonite significantly enhances compressive strength (up to 20% after 90 days) and flexural strength (maximum improvement of 21%). The water permeability was decreased by 29% and improved resistance to steel reinforcement corrosion, demonstrating enhanced durability compared to conventional HPC. However, diminishing returns were observed at higher wollastonite replacement levels (15%), indicating a threshold beyond which mechanical and durability benefits were reduced due to potential issues with fiber dispersion and workability. Our findings suggest that wollastonite is a promising, cost‐effective additive for improving HPC. The study contributes new understandings into optimizing HPC mixtures for greater durability and sustainability, while also reducing the environmental footprint through partial cement replacement. Future research is needed to explore the long‐term performance of wollastonite‐reinforced HPC under different environmental conditions and its combination with other supplementary cementitious materials for further enhancement.

Performance analysis of biodegradable composite using polyvinyl alcohol and pomegranate peel powder for sustainable dry packaging applications

This study focuses on the fabrication of a biodegradable dry packaging material for fruits, vegetables, and flowers, with an emphasis on affordability for street vendors. Approximately 55% of waste originates from packaging materials. To address this issue, a biodegradable Polyvinyl alcohol/Pomegranate peel powder (PVA/PPP) composite film was fabricated. The PVA, a water-soluble synthetic biodegradable polymer, served as the matrix, while PPP, an agro-waste product, was used as the filler. The PVA/PPP films were characterized through optical microscopy, FTIR, XRD, TGA, DSC, moisture absorption analysis, water vapour transmission rate (WVTR), water vapour permeability (WVP), and oxygen permeability testing. The inclusion of PPP enhanced the film’s properties via increasing moisture absorption by 85%, reducing PVA crystallinity index from 33.2 to 17.5%, percentage crystallinity reduced from 73.90 to 0.57%, lowering WVTR from 0.063 to 0.042 g/h.m2, low oxygen permeability and improving thermal stability up to 423 °C. Additionally, the pH of PPP (4.5) contributed to microbial resistance. The fabricated PVA/PPP films were fully biodegradable and produced via green synthesis without any hazardous chemicals. The use of PPP as a filler not only improved film performance but also reduced environmental hazard, demonstrating the material’s suitability for sustainable packaging applications.

Cu-doped nanocomposite Pr2Fe14B/α-Fe ribbons with high (BH)max

Abstract The melt-spun ribbons of nominal composition Pr9Fe84.2-xB6.2P0.3Zr0.3Cux (x=0, 0.5, 1, 2) were prepared at wheel speeds of 21, 27, 30, and 33 ms-1. The XRD patterns show that as the wheel speed increases, the crystallinity of the 2:14:1 hard phase decreases, while that of the α-Fe soft phase increases. The (BH)max, remanence, and coercivity are improved from 63 kJm-3, 0.85 T, and 515 kAm-1 for the Cu-free ribbons to 171 kJm-3, 1.08 T, and 684 kAm-1 with x=0.5. The high squareness ratio of Jr/Js ~ 0.82 at 0.5 at. % Cu (27 ms-1) indicates strong exchange coupling due to small grain sizes of 15 and 30 nm for soft and hard magnetic phases, respectively. The SEM images revealed smooth morphology and uniform element distribution at 0.5 at. % Cu (27 ms-1), contributing to the high magnetic properties. The low recoil permeability (μ rec ) value of 5.466×10-4 to 1.970×10-4 $\frac{T}{k A m^{-1}}$ confirms the strong exchange coupling with x=0.5 (27 ms-1). The initial magnetization curves show that the coercivity mechanism of the Cu-free alloy evolves from the nucleation of the reverse domain to the domain wall pinning as the wheel speed increases, resulting in a high coercivity value of 818 kAm-1 (33 ms-1). Conversely, for the Cuadded alloy, the coercivity mechanism changes from pinning to the nucleation of the reverse domain from low to high wheel speed.

Study on the Vertical Propagation Behavior of Hydraulic Fractures in Thin Interbedded Tight Sandstone

Hydraulic fracturing technology is vital for the efficient extraction of oil and gas from low-permeability tight sandstone reservoirs.Taking the central Bohai oilfield in China as an example, these fields are typically composed of thinly interbedded tight sandstone, characterized by low permeability and significant lithological heterogeneity between layers. Fractures may either be confined, limiting vertical growth and reducing production, or overextend into water-bearing zones, causing contamination and compromising reservoir integrity. Therefore, predicting vertical fracture propagation during field fracturing operations is critical for efficient resource extraction.However, there is still a lack of comprehensive understanding of the mechanisms governing vertical fracture growth offshore.This paper applies numerical simulations based on the finite element method to elucidate the interlayer fracture propagation behavior in low-permeability tight sandstone reservoirs. A fracture propagation model for thin interlayered tight sandstone formations is constructed, and the effects of various factors on hydraulic fracture propagation are systematically analyzed, including geological factors such as interlayer stress contrast, thickness, and differences in elastic modulus, as well as operational parameters including fracturing fluid viscosity and injection rate. This study clarifies the cross-layer propagation patterns of hydraulic fractures under the influence of multiple factors and yields a comprehensive prediction chart for fracture propagation thickness under the combination of complex factors. The results of this research can provide theoretical support for the design of reservoir stimulation operations in low-permeability tight sandstone oilfields.

Enhancing the properties of high-density oil well cement with Qusaiba kaolinite

High-density cement slurries used in oil well cementing often face challenges such as particle settling, poor rheological properties, permeability, and compressive strength degradation, which can compromise zonal isolation and well integrity. This study focuses on using kaolinite, a clay mineral, as an additive due to its potential to improve the performance of high-density cement by modifying key properties. Several concentrations of kaolinite were examined to evaluate their influence on several cement properties such as rheology, thickening time, permeability, porosity, and compressive strength. Additionally, it assesses the impact of kaolinite on cement sheath solids settling using both conventional methods and nuclear magnetic resonance (NMR). The results revealed that an optimal concentration of 1% kaolinite by weight of cement (BWOC) significantly reduced particle settling by 74.4%, enhanced compressive strength by 13%, and lowered permeability and porosity by 74% and 7%, respectively. Additionally, kaolinite improved rheological properties by an 8.4% reduction in plastic viscosity, a 19.4% increase in yield point, and a 30% increase in gel strength. Kaolinite also acted as a retarder, increasing thickening time. These improvements contribute to better cement sheath integrity and wellbore stability, highlighting kaolinite’s potential as an effective additive for high-density cement.

Enhanced Impact Resistance, Oxygen Barrier, and Thermal Dimensional Stability of Biaxially Processed Miscible Poly(Lactic Acid)/Poly(Butylene Succinate) Thin Films

This study investigates the crystallization, microstructure, and performance of poly(lactic acid)/poly(butylene succinate) (PLA/PBS) thin films processed through blown film extrusion and biaxial orientation (BO) at various blend ratios. Succinic anhydride (SA) was used to enhance interfacial adhesion in PLA-rich blends, while blends near 50/50 formed co-continuous phases without SA. Biaxial stretching and annealing, adjusted according to the crystallization behavior of PLA and PBS, significantly influenced crystallinity, crystallite size, and molecular orientation. Biaxial stretching induced crystallization and ordered chain alignment, particularly at the cold crystallization temperature (Tcc), leading to a 70–80-fold increase in impact resistance compared to blown films. Annealing further enhanced crystallinity, especially at the Tcc of PLA, resulting in larger crystallite sizes. BO films demonstrated reduced thermal shrinkage due to improved PLA crystalline structure, whereas PLA-rich blown films showed higher shrinkage due to PLA’s lower thermal resistance. The SA-miscibilized phase reduced oxygen transmission in blown films, while BO films exhibited higher permeability due to anisotropic crystal orientation. However, the annealing of BO films, especially at high temperature (Tcc of PLA), further lowered oxygen permeability by promoting the crystallization of both PLA and PBS phases. Overall, the combination of SA compatibilization, biaxial stretching, and annealing resulted in substantial improvements in mechanical strength, dimensional stability, and oxygen barrier properties, highlighting the potential of these films for packaging applications.

Study on the Oxidation Behavior of TiB2-CeO2-Modified (Nb,Mo,Cr,W)Si2 Coating on the Surface of Niobium Alloy

A novel TiB2-CeO2-modified (Nb,Mo,Cr,W)Si2 coating was prepared on a Nb-5W-2Mo-1Zr alloy substrate using two-step slurry sintering and halide-activated pack cementation to address the limitations of a single NbSi2 coating in meeting the service requirements of niobium alloys at elevated temperatures. At 1700 °C, the static oxidation life of the coating exceeded 20 h, thus indicating excellent high-temperature oxidation resistance. This was due to the formation of a TiO2-SiO2-Cr2O3 composite oxide film on the coating surface, which, due to low oxygen permeability, effectively prevented the inward infiltration of oxygen. Additionally, the dense structure of the composite coating further enhanced this protective effect. The composite coating was able to withstand over 1600 thermal shock cycles from room temperature to 1700 °C, and its excellent thermal shock performance could be attributed to the formation of MoSi2, CrSi2, and WSi2 from elements such as Mo, Cr, and W, which were added during modification. In addition to adjusting the difference in thermal expansion coefficients between the layers of composite coatings to reduce the thermal stress generated by thermal shock cycles, the formation of silicide compounds also improved the overall fracture toughness of the coating and thereby improved its thermal shock resistance.

Bacterial cellulose production through the valorization of waste apple pulp and stale bread

AbstractIn this work, stale bread and waste apple pulp were used as feedstocks for the production of bacterial cellulose (BC). A glucose-rich solution was prepared from stale bread by dilute acid hydrolysis, while an extract comprising fructose and glucose was obtained from the waste apple pulp, which was used for cultivating Komagataeibacter xylinus DSM 2004, either as sole feedstocks or supplemented with Hestrin-Schramm medium. Supplementation significantly improved BC production: 3.38 ± 0.09 g/L for waste apple pulp extract and 2.07 ± 0.22 g/L for stale bread hydrolysate. There was no significant impact on BC chemical structure or fiber diameter, but the biopolymer produced from waste apple pulp extract had slightly higher crystallinity (CI = 59–69%) and lower thermal degradation temperature (Tdeg = 341–350 ℃) than that of the stale bread hydrolysate (CI = 55%; Tdeg = 316–320 ℃). Moreover, supplementation of the waste apple pulp extract led to the preparation of thicker membranes, with higher Young’s modulus, tension, and deformation at break but lower water uptake capacity and lower permeability to O2 and CO2. These results show that waste apple pulp and stale bread are suitable feedstocks for BC production and the cultivation conditions can be adjusted for tailoring the biopolymer’s mechanical and barrier properties to suit different applications.