Release Rate Research Articles

Ebullition drives high methane emissions from a eutrophic coastal basin

The production of methane in coastal sediments and its release to the water column is intensified by anthropogenic eutrophication and bottom water hypoxia, and it is still uncertain whether methane emissions to the atmosphere will be enhanced. Here, we assess seasonal variations in methane dynamics in a eutrophic, seasonally euxinic coastal basin (Scharendijke, Lake Grevelingen). In-situ benthic chamber incubations reveal high rates of methane release from the sediment to the water column (74–163 mmol m−2 d−1) during monthly measurements between March and October 2021. Comparison of these in-situ total benthic methane fluxes and calculated diffusive fluxes point towards a major role for ebullition. In spring and fall, when the water column was oxic, microbial removal of dissolved methane occurred aerobically in the bottom water. In summer, in contrast, dissolved methane accumulated to concentrations of up to 67 μmol L−1 below the oxycline. Shifts in δ13C–CH4 and δD-CH4 towards higher values and the abundant presence of methane oxidizing bacteria point towards removal of methane around the oxycline, likely through both aerobic and anaerobic pathways, with the latter possibly linked to iron oxide reduction. Shifts in δ13C–CH4 and δD-CH4 to lower values above the oxycline indicate that bubble dissolution contributed to dissolved methane. Methane emissions to the atmosphere were observed in all seasons with the highest, in-situ measured diffusive fluxes (1.2 mmol m−2 d−1) upon the onset of water column mixing at the end of summer. Methane release events during the measurement of in-situ water-air fluxes and model calculations point towards a flux of methane to the atmosphere in the form of bubbles, which bypass the microbial methane filter. The model calculations suggest a potential year-round ebullitive methane flux between 30 and 120 mmol m−2 d−1. We conclude that methane emissions from eutrophic coastal systems may be much higher than previously thought because of ebullition.

Pomegranate peel extract incorporated soy protein isolate/Artemisia sphaerocephala Krasch. gum composite films for fresh-cut apples preservation

The objective of this study was to prepare an active packaging film using phosphorylated soy protein isolate (PPS) and Artemisia sphaerocephala Krasch. gum (ASKG) as film matrices, with the incorporation of pomegranate peel extract (PPE) to preserve fresh-cut apples. The results showed that PA-PPE (PPS/ASKG-PPE) films significantly increased thickness by 24.47 %, tensile strength by 58.76 %, and elongation at break by 30.48 %. Additionally, water vapor permeability and oxygen permeability decreased significantly to 6.17 × 10−13 and 0.62 × 10−13 Kg•m•m−2•s−1•Pa−1, respectively. FTIR, XRD, and SEM analyses confirmed the formation of intermolecular hydrogen bonds between PPS, ASKG, and polyphenols extracted from pomegranate peel, indicating excellent compatibility. Furthermore, radical scavenging activity experiments demonstrated that these films exhibited a remarkable ability to scavenge DPPH and ABTS+ radicals up to 70.44 % and 74.28 %, respectively, when the PPE content was at 3 wt%. Moreover, PPS could achieve a sustained release effect on polyphenols with a relatively low release rate (63.83 %) even after seven days' time elapsed. Finally, the PA-PPE film displayed superior performance in reducing the weight loss and browning index of fresh-cut apples within 24 h of storage. The development of PA-PPE film could promote sustainable resource protection and demonstrate promising prospects in the field of fresh-cut fruit packaging.

Multi-functional Finishing of Viscose Fabrics Based on Tea Polyphenols: Integrated Flame Retardant, Antibacterial, Hydrophobic, and UV-resistant Functionalities

Tea polyphenols (TP) are endowed with numerous outstanding properties due to their natural structure, and their use in the preparation of multifunctional finishing agents is a novel topic. In this paper, a multifunctional finishing agent, PAT, was prepared by using phytic acid and TP as raw materials and finished on the surface of viscose fabrics to obtain PAT-100. After measurement, the limiting oxygen index of PAT-100 achieved 32.9%, and the peak heat release rate was reduced by 90%. Due to the presence of polyphenolic groups, PAT exhibited excellent inhibitory effects on Staphylococcus aureus and Escherichia coli, and the UPF value was improved to 53.2. Furthermore, this system also improved the hydrophobicity of viscose fabrics, and the breaking force retention in the warp and weft directions reached 130% and 156%, respectively. This work presents new ideas for TP in the field of multifunctional finishing and increases the added value of viscose fabrics.

Formulation, Design, Optimization, and Characterization of Novel Long-acting Injectable Dosage Form of Anti-psychotic Drug

Background: The current research aimed to create and analyze a new long-acting Brexpiprazole (BRX) injectable for successful anti-psychotic drug therapy in order to decrease dosage frequency and increase patient compliance. Systems for drug transport to particular body sites or regulating release rates with accuracy are known as drug delivery systems (DDS). By affixing the drug to a carrier particle like liposomes, nanoparticles, microspheres, etc., which modifies the drug's absorption and release properties, using carrier technology, drugs may be delivered in an intelligent manner. Methods: Utilizing Resomer RG 502 H and RESOMER® RG 752 H extended-release Polymer, Using a quasi-emulsion solvent diffusion, microspheres were made, and emulsification and solvent evaporation process. Results: The produced microspheres were assessed for stability tests, in vitro drug release, flow characteristics, and drug entrapment efficiency. FTIR experiments were used to establish how well the drug excipients worked together. The acarbose microspheres that were created had an 89.9 to 96.1 percent drug entrapment efficiency. The impact of factors like polymer content on medication release was studied. The Stability study of the formulation was carried out under different conditions, and data were established. Comparative pharmacokinetic studies between marketed oral formulation and Brexpirazole microsphere test formulations in Wistar/SD Rats were carried out and concluded. Conclusion: Brexpiprazole (BRX) novel long-acting injectable formulation, could be used effectively for the treatment of mentally challenged anti-psychotic patients worldwide.

Silver Nanoparticulate Carriers: A Significant Development in Nanotechnology

Background: For centuries, silver has been known for its anti-bacterial effects. It also helps in the prevention and control of various infections. Silver, when synthesized in nano-size, is much more effective, so the trend of using silver nanoparticles in treating mild bacterial diseases to deadly infectious diseases has increased rapidly. Methods: Silver nanoparticles can be synthesized by physical, chemical, and biological methods. Nanoparticles are developed in different shapes and have a wide range of sizes, with the purpose of controlling the release rate and content of the drug’s dose. The nanoparticles can be administered via oral, pulmonary, dermal, and intravenous routes. Results: Silver nanoparticles have been used in treating diseases, such as cancers, diabetes, etc., by targeted drug delivery and in cosmetics, wound healing, diagnostics, water purifying, bio-imaging, air purification, etc. The research on the novel applications of silver nanoparticles merits its medical application, and this utility aspect is granting patented technologies. The utilization of silver nanoparticles has enhanced in recent times due to their effectiveness in the specified diseased state. Conclusion: Studies have indicated that the drugs developed using silver nanoparticles manifest safety as they are biocompatible; thus, silver nanoparticles display a promising role in developing futuristic medical therapeutic strategies.

YAP phosphorylation within integrin adhesions: Insights from a computational model

Mechanical and biochemical cues intricately activate Yes-associated protein (YAP), which is pivotal for the cellular responses to these stimuli. Recent findings reveal an unexplored role of YAP in influencing the apoptotic process. It has been shown that, on soft matrices, YAP is recruited to small adhesions, phosphorylated at Y357, and translocated into the nucleus triggering apoptosis. Interestingly, YAP Y357 phosphorylation is significantly reduced in larger mature focal adhesions on stiff matrices. Building upon these novel insights, we have developed a stochastic model to delve deeper into the complex dynamics of YAP phosphorylation within integrin adhesions. Our findings emphasize several key points: firstly, increasing the cytosolic diffusion rate of YAP correlates with higher levels of phosphorylated YAP (pYAP); secondly, increasing the number of binding sites and distributing them across the membrane surface, mimicking smaller adhesions, leads to higher pYAP levels, particularly at lower diffusion rates. Moreover, we show that the binding and release rate of YAP to adhesions as well as adhesion lifetimes significantly influence the size effect of adhesion-induced YAP phosphorylation. The results highlight the complex and dynamic interplay between adhesion lifetime, the rate of pYAP unbinding from adhesions, and dephosphorylation rates, collectively shaping overall pYAP levels. In summary, our work advances the understanding of YAP mechanotransduction and opens avenues for experimental validation.

Thermal, mechanical property and flame retardant analysis of bio-based rigid polyurethane foam modified with expandable graphite

As an energy-efficient building material, rigid polyurethane foam (RPUF) has attracted attention. However, there are still great challenges in how to easily prepare RPUF materials with good mechanical properties, flame retardant properties, thermal insulation and other properties. In the current work, expandable graphite (EG)-modified lignin-based polyol (RPUF) was prepared by a one-step method. Thermogravimetric analysis was used to study the pyrolysis of modified foams under nitrogen conditions. It was found that the RPUF-4 with an EG of 10 wt% had the highest the apparent activation energy (E), integral procedural decomposition temperature (IPDT), initial temperature and residue rate. And RPUF-4 also had excellent thermal insulation properties. In addition, RPUF-4 exhibited excellent flame retardancy and smoke suppression properties (peak heat release rate (RHRR), total heat release rate (THR) and Ds were 65.46%, 23.92% and 45.94% lower than those of the unadded RPUF, respectively). At the same time, RPUF-4 also had good mechanical properties and energy absorption properties. These results will lay the foundation for the development and application of RPUF in the field of building insulation.

Experimental study on the effects of n-butanol and n-propanol on the spray and combustion characteristics of diesel/biodiesel blends in a constant volume combustion chamber

The depletion of fossil fuel resources and the escalating environmental impact of greenhouse gas emissions have intensified the global exploration of renewable and sustainable energy sources. Biodiesel produced from vegetable oils and animal fats has become a promising alternative to conventional diesel fuel due to its renewability and lower carbon emission. This study investigates the differences in spray, combustion and flame characteristics between soybean-based biodiesel blended with propanol and butanol at various ratios. The results indicate that the liquid spray penetration length of biodiesel mixed with propanol and butanol exceeds that of soybean-based biodiesel. And the increase of spray penetration is accompanied by a longer flame lift-off length, which indicates the improvement of spray characteristics. Regarding combustion, alcohol-fuel blends exhibit a reduction in peak combustion pressure but an increase in peak apparent heat release rate. Additionally, these fuels show a shorter ignition delay and combustion duration. The peak natural flame luminosity is lower for alcohol fuels, suggesting their potential to reduce carbon soot production and support low-carbon combustion. These experimental results contribute to advancing research on cleaner, more efficient and renewable fuels, thereby reducing reliance on conventional fossil fuels.

An Experimental Investigation of 1,2-dimethoxy ethane as a Fuel Additive in Biodiesel-Fueled Diesel Engine

Recently, researchers have focused on the addition of various additives to biodiesel and other petroleum-derived fuels to improve combustion characteristics and reduce pollutant emissions in internal combustion engines. This study explores the effects of integrating 1,2-dimethoxy ethane (1,2-DME) into reference fuels (RF), including 100% diesel (D100), 100% biodiesel (B100), and a blend of 50% diesel with 50% biodiesel (B50). In the experiment, 1,2-DME is added at volumes of 5%, 10%, and 15% while engine load is at 25%, 50%, and 75%. In-cylinder pressure and temperature, heat release rate (HRR), knock intensity (RI), combustion duration (CD), ignition delay (ID), brake thermal efficiency (BTE) and pollutant emissions such as carbon monoxide (CO), nitrogen oxides (NOx), hydrocarbon (HC), and smoke opacity are all evaluated. The findings reveal that increasing the 1,2-DME ratio in the reference fuels enhances HRR, in-cylinder pressure, and temperature. Notably, adding 10% 1,2-DME to D100 at 25% engine load significantly increases HRR by approximately 28.65%. Generally, incorporating 1,2-DME reduces ignition delay, shortens ignition duration and intensifies knock (RI). Analysis of pollutant emissions indicates an increase in nitrogen oxide (NOx) emissions but a reductions in carbon monoxide (CO) and hydrocarbon (HC) emissions with 1,2-DME addition. Furthermore, adding 15% 1,2-DME to D100 at 25% engine load reduces smoke opacity by 59.2%. In summary, the significant effects of 1,2-DME on reference fuels indicate its potential as a viable alternative fuel additive.

Experimental study on the transitional behavior of the room fire under sub-atmospheric pressures

Fuel diffusion combustion and flame behavior within a confined space is a fundamental scientific problem in the energy and combustion field, it involves complicated chemical reaction, fire behavior, thermal dynamics, heat transfer, room-opening flowing and sub-processes of over-ventilated and under-ventilated room fire. However, previous classical knowledges and models about it are usually at standard atmospheric pressure (100 kPa), no work considers the room fire evolution and flame behavior within the room for various sub-atmospheric pressures. In this paper, the experiment is carried by utilizing a 0.3 m × 0.3 m × 0.3 m reduced-scale cubic room with an opening of various dimensions using propane as fuel to simulate fuel combustion inside, which was placed at the Low Pressure Chamber creating various atmospheric pressures. The flame behavior and temperature evolution within the room was recorded and measured with 693 experimental conditions. The experimental results show that, (1) the air inflowing rate through opening into room and heat release rate within the room increase with atmospheric pressure; (2) the flame extinction or reaching well-mixed condition are more easily occurred for lower atmospheric pressure and opening dimension. These characteristic parameters and fire behaviors could be well described by new corrected opening ventilation factor involving effect of atmospheric pressure and the opening dimension. The research work fills the gap in basic scientific research of building fire at sub-atmospheric pressures, which also has important practical applicability of urban building fire protection design code (such as the materials in wall) in different altitudes, room fire suppression, and protecting urban safety.

17β-Estradiol Nanoparticles Increase Endothelial Nitric Oxide Synthase Expression Through Akt Pathway in Rats with Myocardial Infarction

17β-estradiol can effectively slow down progression of myocardial infarction (MI), and is expected to have more curative effects. Therefore, this study investigated the mechanism underlying cardioprotective role of 17β-estradiol NPs in rats with MI. After construction of rat MI model and preparation of 17β-estradiol NPs, the rats were administered with 17β-estradiol alone, 17β-estradiol NPs and Akt agonist or inhibitor. Distribution of 17β-estradiol NPs was observed by fluorescence microscope and release curve was detected. After treatment, echocardiography was conducted to measure the cardiac function indicators. With HE staining to observe myocardial tissue, RT-qPCR and Western blot determined levels of AKT and eNOS. The NPs were relatively uniform in size and round in shape; and cumulative release rate and concentration of 17β-estradiol in rats reached highest level on 30th day. Treatment with 17β-estradiol or 17β-estradiol NPs importantly increased survival rate of MI rats and decreased MI area while improving LVSP, LVDP, and HR. Moreover, the 17β-estradiol NPs had the smallest MI area. The myocardial tissue of rats in the 17β-estradiol NP group was closely arranged, and myocardial collagen was significantly reduced. The 17β-estradiol NPs increased the mRNA level of eNOS and Akt when eNOS expression was related to Akt expression. 17β-estradiol NPs can therefore increase the expression of eNOS by activating Akt signaling pathway, thereby relieving the myocardial injury in rats, hindering progression of MI.

Amphiphilic Diblock Copolymers of Polyisobutylene-b-Poly(2-Ethyl-2-Oxazoline) via Cationic Polymerization

A series of amphiphilic polyisobutylene-b-poly(2-ethyl-2-oxazoline) (PIB-b-PEOX) diblock copolymer/Ag nanoparticle composites were successfully in-situ synthesized via cationic ring-opening polymerization of 2-ethyl-2-oxazoline (EOX) with high initiation efficiency by using allyl bromide end functionalized polyisobutylene (PIB-allylBr) as a macroinitiator and AgClO4 as a coinitiator. The microphase separation formed in the resulting PIB-b-PEOX diblock copolymers due to the thermodynamic imcompability of hydrophilic PEOX segments and hydrophobic PIB segments. The micromorphology of phase separation is dependent on the copolymer composition, in which sea-island micromorphology formed for PIB118-b-PEOX80 and bicontinuous phase micromorphology formed for PIB118-b-PEOX97. The micelles with nano-scale size in the range of 15 - 80 nm and having high drug loading rate of ca. 48.9% can be formed by self-assembly of the amphiphilic diblock copolymers in n-hexane. The drug cumulative release rate can be increased with an increase in the proportion of PEOX segments, due to the strong interaction between ibuprofen and the PEOX segments. The hydrophilicity of the PIB-b-PEOX diblock copolymer surfaces can be improved after ethanol vapor induction. The PIB-b-PEOX diblock copolymers behave biocompatibility and good anti-protein adsorption property. The amphiphilic PIB-b-PEOX) diblock copolymer /Ag nanoparticle composites exhibit high antibacterial efficiency for Gram-negative bacterium (E. coli) and Gram-positive bacterium (S. aureus). To the best of our knowledge, this is the first example of PIB-b-PEOX diblock copolymer/Ag nanoparticle (6.4 ±2.6 nm) composites synthesized in-situ with good biocompatibility, anti-protein adsorption, and antibacterial properties, which would have potential applications for drug delivery and anti-protein coating in biomedical areas

Efficient recovery and utilization of phosphorus from sewage sludge via alkalinous fenton-like oxidation with pyrolysis-modified red mud: Full resource utilization attempt

Red mud (RM) and sewage sludge (SS) are growing massive industrial wastes, and recycling utilization is considered a suitable disposal method. In this study, a novel Fenton-like catalyst was synthesized through co-pyrolysis with RM and SS with high alkaline endurance, presenting a sustainable full resource utilization of the SS. The advanced oxidation process effectively breaks down the SS structure to release phosphorus(P) for struvite recovery. The residual SS can be repurposed as fuel following direct flocculation and dehydration. There is no need for complex pH adjustments throughout. XRD pattern revealed zero valent iron (ZVI, Fe0) as the primary catalyst phase. Experimental findings demonstrated that H2O2 efficiently disrupts bacterial structures, leading to a significant reduction in bound extracellular polymer (TB-EPS) in the SS. It was observed that the release rate of P reached nearly 100% after 60 min of reaction. The purity of recycled struvite reaches 94.9%, and the heavy metal content meets national standards. Planting experiments indicated that recycled struvite exhibited superior fertility compared to commercial fertilizers. The proposed sustainable resource production and recycling process of SS strongly supports the construction of a "city without waste".

Kinetic analysis and calculation correction methods for moisture evaporation rate in pine lignocellulosic biomass

This study investigates the kinetics of moisture evaporation in pine wood during the drying stage, focusing on analyzing thermogravimetric (TG) curves. The research is based on the kinetic rate model and TG curves obtained at various heating rates, specifically 5, 10, 15, and 20 K/min for the heat release rate, within a temperature range from room temperature to 473 K. Utilizing thermogravimetric experiments and the kinetic rate model, the apparent activation energy and pre-exponential factor are calculated. Further refinement of these calculations is achieved using the Nelder-Mead algorithm. The results show good agreement between the average values of the apparent activation energy (37.88 kJ/mol) and pre-exponential factor (4458.20 s−1) and experimental measurements in the initial and later drying stages, with discrepancies noted in the middle stage. Establishing a relationship between the correction coefficients of these parameters and the heating rate leads to a reduction in calculation errors. Notably, the pre-exponential factor is found to be influenced by heating rates, while the apparent activation energy remains relatively stable. Moreover, the errors are significantly reduced after correction, and the error curve of 10 K/min is the most significant. Overall, the proposed correction method holds promise for accurately calculating moisture evaporation rates in lignocellulosic biomass, offering valuable insights for biomass drying applications.

Impinging ceiling flame behaviors induced by wall-attached gaseous fuel fires at one end in a narrow building corridor: Different phases and generalized correlations

This work investigated the flame extension behavior after impinging upon a ceiling induced by wall-attached fires at the closed end in a narrow building corridor. Experiments were conducted in a reduced scale corridor with one end closed and the other opened, under various fire heat release rates and source-ceiling heights (from 0.05 m to 0.50 m) of totally 353 test conditions. The flame morphological characteristic parameters involving the flame extension length in the center of the ceiling and in the two sides were measured and analyzed comprehensively. By a careful observation, it was found that, as the fire heat release rate increased or the source-ceiling height decreased, the ceiling flame extension behavior can be divided into different behavior phases: the flame spreads to the two sides after impinging the narrow building ceiling; flame extends longitudinally after reaching side walls, presenting a semi-elliptical shape; flame in the two sides extends farther than that in the center of the ceiling, presenting a “U” shape; and flame presents a cellular structure (the fire source is near the building ceiling). The dimensionless critical fire heat release rates for the transition of these phases were identified, and non-dimensional correlations were obtained for the prediction of flame extension lengths of different phases. This work provides new observations of different phases and generalized correlations for impinging ceiling flame behaviors induced by wall-attached gaseous fuel fires at one end in a corridor.

Tailored alginate sponges loaded with κ-carrageenan beads for controlled release of curcumin

This study presents an innovative approach to develop and characterize an alginate sponge containing κ-carrageenan (κ-CRG) beads loaded with curcumin. The beads were fabricated using varying concentrations of κ-CRG, and their properties were extensively evaluated using inverted phase-contrast microscopy, Scanning Electron Microscopy (SEM), FTIR, swelling behavior, mass distribution, encapsulation efficiency, in vitro drug release and kinetics of drug release. Beads formulated with specific concentrations of κ-CRG that exhibited optimal performance were then integrated into an alginate sponge matrix, which underwent similar comprehensive testing procedures as the individual beads. The characterized beads displayed a spherical morphology, a notable swelling degree of approximately 146 %, excellent mass uniformity, encapsulation efficiencies higher than 90 % and drug release rate exceeding 70 %. Moreover, the alginate sponge formulation demonstrated a satisfactory drug release profile of 67.9 ± 0.6 %. In terms of drug release kinetics, the Higuchi model was the most effective in explaining the release of curcumin from beads and sponge. These findings underscore the potential of both the beads and the sponge as effective vehicles for the controlled delivery of curcumin, positioning them as promising candidates for pharmaceutical applications across various fields.

A DOPO-eugenol linear siloxane as a highly effective liquid flame retardant also imparting improved mechanical properties to an epoxy amine network

A liquid bio-derived eugenol-containing phosphorus silicone hybrid molecule (EGDS-DOPO) that endows excellent flame-retardancy and enhanced mechanical performance to an epoxy amine network at low levels of addition was successfully synthesized and characterised. The EGDS-DOPO significantly improved the flame retardancy requiring only 5 wt% of EGDS-DOPO to achieve a limiting oxygen index (LOI) of 34.9 % and a UL 94 V-0 rating. Cone calorimetry measurements reveal a reduction of the peak heat release rate, the total heat release, and total smoke production by 62.2 %, 34.0 % and 47.5 %, respectively when EGDS-DOPO concentration was 20 wt%, compared to the unmodified epoxy network. Viscosity remained low throughout cure, and despite some retardation of reactivity, the epoxy amine resin remains fast curing and suitable for liquid moulding composite fabrication technologies. Moreover, the modified EGDS-DOPO epoxy networks display a glass transition temperature (Tg) between 218.5 °C and 174.1 °C, a hydrophobic surface with water contact angle of 97.5°–106.6°, a low moisture ingress of 2.35 %–2.91 %, and improved overall mechanical properties in flexure (maximum 39.8 % increase in flexural strength and 27.0 % in flexural modulus), compression (maximum 24.5 % and 35.0 % increase in compressive strength and modulus, respectively), and fracture toughness (maximum 28.0 %).

The preparation of ammonium polyphosphate@ nickel/cobalt-layered double hydroxide and its application as flame retardant in thermoplastic polyurethane

Inspired by the significant synergistic effect of transition metals and ammonium polyphosphate (APP) on flame reatrdancy, a nickel/cobalt-layered double hydroxide derived from a selected zeolitic imidazolate framework-67 (APP@NiCo) was constructed onto the surface of APP to enhance the fire safety of thermoplastic polyurethane (TPU). The results demonstrated that TPU containing 6 wt% APP@NiCo exhibited a LOI value of 27.7% and achieved UL-94 V-0 rating. Furthermore, there was a significant reduction in the peak heat release rate, heat release rate, and total smoke production by 72.8%, 37.5% and 56.9%, respectively. The remarkable improvement in flame retardancy was contributed to the highly synergistic charring catalysis of APP and dual transition metals cobalt and nickel, which effectively promoted the formation of robust char layers during TPU combustion for enhancing fire safety.

A new strategy for constructing ZIF-67@PBA core-shell 3D cross-heterostructures for improving fire safety of TPU at ultra-low addition amount

Thermoplastic polyurethane (TPU) has an extensive application in many different industries. However, serious fire hazards and smoke toxicity have been the main reason limiting its wide application. Therefore, it is necessary and urgent to perform flame retardant and smoke suppression treatment for TPU. In recent years, metal-organic framework compounds (MOFs) have very promising application prospects in the fields of flame-retardant polymer composites. However, there is a problem of low flame-retardant efficiency for the original MOFs alone in polymer composites. It is reported the multi-level and multi-structured flame-retardant system has better flame-retardant efficiency than the traditional structures. So, the dual MOF core-shell heterostructure may have more effective heat reduction and smoke suppression than any single component. In this paper, a core-shell 3D cross-heterostructures nanohybrid (ZIF-67H@PBA) was prepared using ZIF-67H as the host MOF and Prussian blue nanocubes (PBA) as the guest MOF. It has been found that TPU/ZIF-67H@PBA composites with ultra-low additions have excellent fire safety. Compared with those of pure TPU, the peak heat release rate (PHRR), total smoke release (TSP), and smoke factor (SF) of the samples with 0.5wt% ZIF-67H@PBA were reduced by 33.6 %, 47 %, and 61 %, respectively. At the same time, a cone calorimeter (CCT), a homemade soot sampling device and a gas chromatography-mass spectrometry (GC–MS) coupling with each other were constructed and used to demonstrate the most realistic effects of flame retardants in terms of smoke suppression and toxicity reduction. This work provides a new strategy to design TPU flame retardants.

Combustion synthesis of the (Ti,Zr)B2-(Zr,Ti)C eutectic composites: Structure formation and properties

The macrokinetic characteristics of combustion of the quaternary Ti-Zr-B-C mixture as well as the mechanism and stages of phase formation for the synthesis products were investigated. The mechanical and thermophysical properties of the hot-pressed boride/carbide ceramics with eutectic composition (Ti,Zr)B2-43%at.(Zr,Ti)C were measured. Preliminary mechanical alloying (MA) of the (Zr + Ti) mixture was shown to yield Ti/Zr granules having a laminar structure and consisting of alternating layers of titanium, zirconium, and (Zr,Ti)ss solid solution. The method used to prepare reaction mixtures and the initial temperature T0 increased within the range of 20–370 °C have virtually no effect on combustion temperature, which is 2260–2400 °C, while higher T0 increases the combustion rate by a factor of 1.5–2. The use of MA Ti/Zr granules reduces the combustion rate as well as the specific heat release amount and the heat release rate. Time-resolved X-ray diffraction data showed that binary carbides (Zr1-xTix)C and diborides (Ti1-yZry)B2 of variable stoichiometry are formed in the combustion wave of the Ti-Zr-B-C reaction mixtures within less than 0.25 s. The carbide and diboride phases are formed simultaneously; the use of MA Ti/Zr granules in the reaction mixtures reduces the content of solid solutions of variable stoichiometry among the reaction products. The ceramics fabricated using a combination of combustion synthesis and hot pressing have a dense and homogeneous structure that consist of bonded grains of the diboride (Ti0.80Zr0.20)B2 and carbide (Zr0.83Ti0.17)C phases having the following properties: density, 5.3 g/cm3; hardness, 22.9 GPa; fracture toughness, 4.7 MPa m0.5; heat capacity, 0.52 J/(g·K); thermal diffusivity, 11.67 mm2/s; and thermal conductivity, 33.28 W/(m·K).