Release Rate Research Articles

Impact of metakaolin on hydration properties of magnesium phosphate cement

The degradation of mechanical properties in magnesium phosphate cement (MPC) is commonly observed under conditions of rapid heat release and high ambient temperature. To mitigate this phenomenon, the incorporation of metakaolin has been investigated as a means to reduce the hydration heat of MPC and enhance its mechanical properties at elevated temperatures. Experimental findings reveal a pronounced influence of metakaolin on the heat flow behavior of MPC. Specifically, the addition of a small fraction of metakaolin (not exceeding 20wt%) leads to an accelerated heat release rate during the initial 0.13hours, followed by a substantial reduction in the heat release rate with further increments of metakaolin. Furthermore, the inclusion of metakaolin significantly improves the mechanical properties of MPC. For instance, a composition comprising 30% metakaolin yields a notable 79.2% increase in strength after 7 days. It is worth noting that temperatures below 400℃ are found to have an adverse impact on the mechanical properties of MPC, whereas a temperature range encompassing 600℃>T>400℃ enhances these properties due to vitrification at high temperatures. Importantly, MPC incorporating metakaolin exhibits superior mechanical performance compared to its metakaolin-free counterpart across all tested temperatures, which can be attributed to the attainment of a denser microstructure facilitated by metakaolin incorporation.

Synthesis of oxygen‐rich functional groups biochar for high‐efficiency adsorption of herbicide and as a potential carrier for pH‐responsive slow release

AbstractTo improve the utilization rate of herbicides and reduce their environmental residues, it is urgent to develop a simple and low‐cost method to prepare slow‐release pesticides. In this study, a biochar (280CPFe) with a high surface area and rich oxygen‐containing functional groups was synthesized by low temperature (280°C) boiling strategy, which was used as a carrier to prepare pH‐responsive slow‐release herbicide. The obtained biochar has a high adsorption capacity of 153.59 mg·g−1 for quinclorac (QNC). The release rates of QNC‐280CPFe are 21%, 56%, and 90% at the initial pH of 3, 5, and 11, respectively. The controlled release behavior of QNC‐280CPFe is related to its adsorption mechanism, in which the pore filling and functional group adsorption are mainly responsible for the adsorption of QNC on 280CPFe. Compared with QNC alone, QNC‐280CPFe slow‐release herbicide has a good control effect on Barnyard grass but does not affect the normal growth of rice. Therefore, this study provides a simple, low‐cost cost, and environmentally friendly biochar carrier for preparing slow‐release herbicide, improving its utilization rate and reducing its environmental pollution risk.

Knockdown of miR-155 alleviates skin damage in rats with chronic spontaneous urticaria by modulating the JAK/STAT signaling pathway

ObjectiveThe aim of this study was to investigate the role and mechanisms of miR-155 in chronic spontaneous urticaria (CSU).MethodsThe expression level of miR-155 in the skin tissues of patients with CSU and experimental rats were detected by RT-qPCR, followed by the measurement of the histamine release rate in the serum through the histamine release test. Besides, hematoxylin & eosin staining was used to observe the pathological changes of the skin tissues; Corresponding detection kits and flow cytometry to measure the changes of immunoglobulins, inflammatory cytokines and T cell subsets in the serum of rats in each group; and western blot to check the expression level of proteins related to JAK/STAT signaling pathway in the skin tissues.ResultsKnockdown of miR-155 reduced the number and duration of pruritus, alleviated the skin damage, and decreased the number of eosinophils in CSU rats. Moreover, knockdown of miR-155 elevated the serum levels of IgG and IgM, decreased the levels of IgA and inflammatory cytokines, and reduced the proportion of CD4 + and CD4 + CD25 + T cells, as well as the CD4+/CD8 + ratio in CSU rats. However, Tyr705 intervention could reverse the effects of knockdown of miR-155 on CSU model rats. Furthermore, we found that knockdown of miR-155 significantly reduced the protein expression of IRF-9, as well as the P-JAK2/JAK2 and P-STAT3/STAT3 ratios in the skin tissues of CSU rats.ConclusionKnockdown of miR-155 can alleviate skin damage and inflammatory responses and relieve autoimmunity in CSU rats by inhibiting the JAK/STAT3 signaling pathway.

Unlocking the Potential of VCI Films: A Comprehensive Study on Protective Efficiency

ABSTRACT Volatile Corrosion Inhibitor films have become an essential tool in safeguarding metal surfaces from corrosion. To maximize the effectiveness of VCI films, it is crucial to understand the relationship between their thermal properties and vapor phase inhibition ability. In this study, the optimal and modified standard test was performed for evaluation of VCI films ability and also investigate how their thermal characteristics influence their protective efficiency via the weight-loss method, and differential scanning calorimetry (DSC) analysis. The results showed that under the simulated and standard test conditions, the steel surface exposed to VCI films shows a model of a “preservative memory for VCI material”, at higher temperature/humidity. This memory is affected by different adsorption power due to the roughness of the surface, humidity and temperature as well as the rate of release of inhibitors. The results of the computational method confirmed that the orientation of the inhibitor molecule when interact with the polymer chain is the determining factor in the inhibition efficiency, consistent with the FTIR results. This behavior caused by chemical or electrochemical reaction with the temperature-dependent release rate of inhibitors has a greater effect on inhibition.

Towards fire-safe, smoke-suppression and recyclable epoxy composite from bio-derived flame retardant

Epoxy-based vitrimers appear as a promising alternative to common epoxy materials. Nevertheless, the possibility of epoxy vitrimers in practical applications is limited by their high flammability. In this study, a novel bio-based casein phosphopeptide chelating zinc (CPP-Zn) is purposely developed, specifically designed to serve as a flame retardant and smoke suppressant for epoxy vitrimer, operating through a condensed phase mechanism. To further enhance the fire safety of epoxy resins, DOPO derivative (DDP) is synthesized through grafting with bio-based itaconate and subsequently used as a synergistic flame retardant in combination with CPP-Zn. DDP exhibits gas phase flame retardant mechanism through the release of free radical scavangers generated during combustion. As a result of the combination of condensed and gas phase effect, the composite achieves self-extinguishing within 1 second, attains a V-0 rating in UL-94 testing, and boasts an LOI of 32.3 %. Additional, it shows a remarkable 73.7 % reduction in heat release rate (HRR) and 27.2 % in total smoke production (TSP) compared with neat epoxy vitrimer. The experimental results also evidence that the characteristic features of vitrimers, self-healing and recyclability, have been retained in the prepared flame-retarded composites. The remolded 50D/EST-25Cz is still able to maintain 72.2 % of its tensile strength. This opens promising avenues for the development of highly fire-safe and eco-friendly epoxy resins.

Modification research on the hydrogen storage performance of bimetallic oxide Zn2Ti3O8 on MgH2

In this study, flake Zn2Ti3O8, TiO2 and rod ZnO catalysts were successfully synthesized by hydrothermal and calcination methods, and the catalytic performance of the three catalysts for MgH2 was compared. Notably, Zn2Ti3O8 had a significant synergistic enhancement effect on the dehydrogenation temperature and desorption kinetics of MgH2. The experimental results showed that the dehydrogenation of MgH2 + 12 wt% Zn2Ti3O8 composite started at about 195 °C, which was about 150 °C lower than that of pure MgH2. Moreover, at 325 °C, MgH2 released only 3.06 wt% H2 in 20 min, whereas the MgH2 + 12 wt% Zn2Ti3O8 composite released the same amount of hydrogen at 250 °C in 3 min. After complete dehydrogenation, the MgH2 + 12 wt% Zn2Ti3O8 composite initiated hydrogen uptake at 40 °C and absorbed about 6.05 wt% of H2 in 60 min at 200 °C. The hydrogen uptake activation energy and dehydrogenation activation energy of the composites were reduced by 24.56 kJ/mol and 44.67 kJ/mol, respectively, when compared to the pure MgH2. Cycling experiments showed that after 20 cycles, the MgH2 + 12 wt% Zn2Ti3O8 composite maintained good cycling stability and the hydrogen storage capacity was still more than 96 %. Therefore, the composite exhibits excellent catalytic and hydrogen storage properties, and has potential applications in improving the hydrogen release rate and reducing the activation energy.

A study of indoor air pollution caused by disinfection equipment as a consequence of infectious waste management

ABSTRACT Infectious waste disinfection is an essential process in medical waste management that may cause release of some pollutants. In this study, the PAHs concentration at the disinfection was investigated. The change in the release rate of PAHs in two including infectious waste reduction and increasing the segregation ratio was estimated. The results showed that the PAHs concentration was 1172 – 2066 ng/m3. The specific concentration of PAHs was 852 ng/ton of infectious waste in average. The annual emission of the PAHs resulting from infectious waste disinfection is estimated to be 612.6 kg. Reduction of infectious waste caused by redefining infectious waste and increasing the segregation ratio leads to reduction of PAHs concentration by 50%. Increasing the ratio of segregation and redefinition of infectious waste that led to reduced waste loading volume are essential measures that reduce the emissions of pollutants as by-products of disinfection.

Gastroretentive fibrous dosage forms for prolonged delivery of sparingly-soluble tyrosine kinase inhibitors. Part 2: Experimental validation of the models of expansion, post-expansion mechanical strength, and drug release

In Part 1, we have introduced expandable gastroretentive fibrous dosage forms for prolonged delivery of sparingly-soluble tyrosine kinase inhibitors. The expansion rate, post-expansion mechanical strength, and drug release rate were modeled for a dosage form containing 200 mg nilotinib. In the present part, the dosage form was prepared and tested in vitro to validate the models. Upon immersing in a dissolution fluid, the fibrous dosage form expanded at a constant rate to a normalized radial expansion of 0.5 by 4 h, and then formed an expanded viscoelastic mass of high strength. The drug was released at a constant rate over a day. For comparison, a particle-filled gelatin capsule with the same amount of nilotinib disintegrated almost immediately, and released eighty percent of the drug content in just 10 min. The experimental data validate the theoretical models of Part 1 reasonably

Half etching of ZIF-67 towards open hollow nanostructure with boosted absorption ability for toxic smoke and fume in epoxy composites

Metal-organic frameworks (MOFs) are favored in the field of flame retardancy due to the catalytic effect of metal nodes on char layer formation and the synergistic flame-retardant effect of organic ligands containing elements such as nitrogen and phosphorus. However, the inherent microporosity of MOFs limits their adsorption efficiency for toxic smoke and flammable gases. In this work, an organic phosphorus-modified MOF with a distinctive nanostructure of hierarchically porous (P-Co-MOF/ZIF) was successfully synthesized. In brief, an amino-functionalized zeolitic imidazolate framework (NH2-ZIF) was initially synthesized through a ligand substitution reaction with ZIF-67. Subsequently, organic phosphorus flame retardants were grafted on NH2-ZIF, and the acidic substances generated during this process were used to synchronously half etch ZIF, resulting in a ZIF with a high specific surface area and unique nanostructure. Through this simple synthetic method, the catalytic ability of transition metals in ZIF is preserved, and organic phosphorus flame retardants are incorporated into ZIF, resulting in the synergistic flame-retardant effect of phosphorus and nitrogen. Additionally, its unique hierarchically porous nanostructure can effectively enhance the adsorption of volatile products during the combustion process, thereby offering outstanding flame retardancy and smoke suppression effects for epoxy resin (EP). The results indicate that adding 2 wt% P-Co-MOF/ZIF to EP can increase the limiting oxygen index value to 29.5%. Furthermore, the peak of heat release rate, total heat release, and total smoke production of the composite material can decrease by 43.3%, 37.9%, and 38.1%, respectively, compared to EP. Therefore, this work will provide new inspiration for designing functional nanostructures and synthesizing efficient flame retardants.

In-situ gel injection of poloxamer-based metamizole provides long-acting antipyretic effects.

Metamizole easily decomposes in the body and has a short action time and low bioavailability. Hence, frequent injection administrations are needed to maintain its plasma concentration. This study aimed to design and develop an in-situ gel based on poloxamer 407 and 188 to assess its long-acting antipyretic effects. The in-situ gel-forming systep00m with optimum sol-gel transition temperature of 35.9°C to 36.3°C could be formed using a combination of P407 at a ratio of 21-23% (w/v) and P188 at a ratio of 2-4% (w/v). In vitro erosion test showed that the in-situ gel's erosion curve and the metamizole release rate both reached about 90% at 6h, revealing a good linear relationship between the in-situ gel erosion and the drug release. In vitro release test with dialysis tube showed that the release of metamizole from the in-situ gel was remarkably slower than that from the metamizole solution. Approximately 85% of metamizole was released in the dialysis tube within 7h, implying a good sustained release effect. Pharmacodynamic study showed that the in-situ gel injection extended the action time of metamizole relative to that when using the metamizole solution. Pharmacokinetic study revealed that the in-situ gel significantly increased the blood serum half-life and area under the curve), contributing to a sustained release and improved bioavailability. This study demonstrated that in-situ gel injection could prolong the action of metamizole in the body to reduce the number of administration times and has good clinical application.

Development of a reduced primary reference fuel – oxymethylene dimethyl ether (PRF-OMEx) mechanism for diesel engine applications

Oxymethylene dimethyl ethers (OMEx), having a chemical formula of CH3O-(CH2O)x-CH3 where x varies from 1 to 5, have been widely considered as a promising fuel to partially replace diesel in CI engines in terms of reducing soot emissions. This work is focused on developing a reduced primary reference fuel (PRF)-OMEx chemical mechanism to better describe the combustion and emission characteristics of gasoline/diesel blends with OMEx. The novelty of this work lies in the fact that the OMEx part of the mechanism is represented not only by OME3 as done in most studies found in literature, but also with other OME chain lengths that is, OME2-4 which are considered to be optimum and better represent the commercial OMEx blends. For this purpose, a detailed OMEx mechanism is reduced by applying different reduction techniques considering a wide range of operating conditions including pressure, temperatures, equivalence ratios and fuel compositions. The result is merged with an already validated PRF mechanism to form a reduced PRF-OMEx mechanism consisting of 213 species and 840 reactions. The newly formed mechanism is validated against a wide set of experimental data including ignition delay times, laminar flame speeds and species concentration profiles. Furthermore, a rigorous set of numerical simulations for various diesel-OMEx blends in a compression ignition engine are carried out at two different operating points to validate the developed mechanism. Simulation results highlight that the developed mechanism not only replicates the experimental behavior in terms of in-cylinder pressure and heat release rate but exhibits a better combustion phasing closer to experimental data when compared with other mechanisms where only OME3 is utilized to represent OMEx. Overall, the developed PRF-OMEx mechanism proves to be realistic and suitable for application in engine combustion simulations involving gasoline/diesel and OMEx blends.

Functionalized Zr‐MOFs for Enhancing Flame Retardancy and Smoke Suppression Performance on TPU

AbstractMetal‐Organic Framework (MOF) materials can be used as flame‐retardants and smoke suppressants for polymers. As a MOF material, UIO‐66(Zr) possesses higher thermal stability and controllable pore size. In this paper, UIO‐66(Zr), NH2‐UIO‐66(Zr), and SiO2, MWCNT, and GO functionalized NH2‐UIO‐66(Zr) was fabricated to improve the flame retardant and smoke suppression performance of thermoplastic polyurethanes (TPU). The experimental results show that compared with neat TPU (LOI value 19.1 %), 2 % usage of UIO‐66(Zr) and NH2‐UIO‐66(Zr) can endow TPU with 26 % LOI value and vertical combustion rating of V‐1. Moreover, SiO2, MWCNT, and GO functionalized NH2‐UIO‐66(Zr) provide TPU with above 27.8 % LOI value and vertical combustion rating of V‐0. Meanwhile, the CCT results showed that the peak heat release rate and total heat release of TPU‐U5 (added 2 % GO‐modified NH2‐UIO‐66(Zr)) are 299.52 Kw ⋅ m−2 and 68.21 MJ m−2, much lower than that of neat TPU, which are 1180.05 Kw ⋅ m−2and 104.87 MJ m−2, respectively. The TGA, char residue EDS and XRD analysis show that SiO2, MWCNT, and GO functionalized NH2‐UIO‐66(Zr) could generate zirconium metal oxide during the combustion process, which acts as a physical barrier to prevent the TPU matrix by promoting the generation of carbonization layer. The zirconium metal oxide and carbonization layer also can confine flammable gases, which can delay the ignition time and hinder the overflow of gas. In addition, NH2‐UIO‐66(Zr) could generate non‐flammable N2 diluting the concentration of flammable gases. The mechanical properties of TPU composites can maintain more than 87 % of the neat TPU after the addition of 2 % SiO2, MWCNT, and GO functionalized NH2‐UIO‐66(Zr). These results indicate that functionalized Zr‐MOFs composites could act as excellent flame‐retardants in TPU.

Self-assembled coatings with durable flame retardancy for EPS foam

Layer by layer (LBL) self-assembly coatings upon expandable polystyrene (EPS) surface play an important role in improving its flame retardancy. However, a large number of layers is needed to achieve a satisfied fire performance, and the coatings are difficult to adhere on the inert EPS surface, resulting in the poor durability. In this work, the surface of EPS was activated by ultraviolet ozone (UVO) with the appearance of oxygen contained groups, then a LBL coating with only two bilayers (branched polyethyleneimine (BPEI)-kaolinite (kaol)-BPEI-diethylene triamine penta (methylene phosphonic acid)) was covalently connected on the EPS surface. Compared with neat EPS, the obtained E-K5D30 sample increased the value of limiting oxygen index (LOI) from 18.8 % to 37.7 %, improved the ignition time from 59 s to 95 s, reduced the peak heat release rate (pHRR) value from 282.0 kW/m2 to 220.9 kW/m2, and enhanced the char residues from 6.3 % to 32.3 % after the combustion. Moreover, an ultraviolet (UV) curing layer with P/N elements was prepared upon E-K5D30 sample to maximize the flame retardant durability. A novel amino-intercalated kaol was used to play a smoke suppression role. The results showed that E-K*5D30-P8N3 sample further increased the LOI to 39.2 %. Even after 12 h washing, the E-K*5D30-P8N3 sample exhibited a slight LOI reduction to 37.8 %, and fire performance index (FPI) value of 0.405 m2·s/kW, showing the successful construction of coatings with good fire safety and flame retardant durability.

In vitro evaluation of ethyl cellulose and polyvinyl pyrrolidone composite nanofibers for transdermal delivery of diclofenac diethylamine

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most prominent painkiller and anti-inflammatory drugs with gastrointestinal (GI) adverse effects. Transdermal drug delivery systems (TDDS) could overcome GI adverse effects associated with oral ingestion of NSAIDs as well as maintaining a prolonged release of the drug. The main aim of this study was to prepare and investigate diclofenac diethylamine (DDA) loaded nanofibers made of ethyl cellulose (EC) and polyvinyl pyrrolidone K90 (PVP) using electrospinning. The impact of penetration enhancers such as nerolidol and farnesol on release profiles through cellophane membranes and other characteristics of nanofibers were also investigated. Based on release studies, some formulations were selected for release examination through rate skin using Franz diffusion cells. To gain insight about potential interactions between drug and polymers FTIR, DSC, and XRD analyses were performed. Morphology examination was also conducted using scanning electron microscopy (SEM). Morphology studies showed that nanofibers made of EC only are greater in the mean diameter than other nanofibers while other formulations were not significantly different from each other regardless of the presence of penetration enhancers. EC nanofibers had the lowest elastic modulus and tensile strength and most elongation at break which makes them the least tough and most flexible nanofibers among all the formulations. The addition of PVP increased the toughness and decreased the flexibility of nanofibers. The addition of nerolidol did not alter the mechanical properties of nanofibers significantly, while the addition of farnesol increased elastic modulus, tensile strength, and elongation at break significantly in a concentration-dependent manner. EC nanofibers had the lowest release rate and lowest total cumulative release content while the addition of PVP significantly improved both of these features. In release studies through cellophane membrane, the addition of 5 % of penetration enhancer slightly increased the release rate while did not significantly alter cumulative release while the addition of 10 % farnesol notably increased the release rate and total cumulative released content. Release studies through rat skin were in accordance with cellophane membrane studies and the formulation with 10 % farnesol had the most release rate and total cumulative release and these findings confirm the positive effect of penetration enhancers. DSC thermogram showed an amorphous state of the drug in fibres and this was supported by XRD results. The FTIR results confirmed that no chemical interaction between the drug and other formulation components has occurred and no new compounds have been formed. Based on these results, the utilization of DDA-loaded PVP and EC nanofibers in conjunction with a penetration enhancer showed significant potential for application in transdermal patches.

Engineered Robust Hydrophobic/Hydrophilic Nanofibrous Scaffolds with Drug-Eluting, Antioxidant, and Antimicrobial Capacity.

Multifunctional nanofibrous architectures have attracted extensive attention for biomedical applications due to their adjustable and versatile properties. Electrospun fabrics stand out as key building blocks for these structures, yet improving their mechanobiological and physicochemical performance is a challenge. Here, we introduce biodegradable engineered hydrophobic/hydrophilic scaffolds consisting of electrospun polylactide nanofibers coated with drug-eluting synthetic (poly(vinyl alcohol)) and natural (starch) polymers. The microstructure of these composite scaffolds was tailored for an increased hydrophilicity, optimized permeability, water retention capacity of up to 5.1 g/g, and enhanced mechanical properties under both dry and wet conditions. Regarding the latter, normalized tensile strengths of up to 32.4 MPa were achieved thanks to the improved fiber interactions and fiber-coating stress transfer. Curcumin was employed as a model drug, and its sustained release in a pure aqueous medium was investigated for 35 days. An in-depth study of the release kinetics revealed the outstanding water solubility and bioavailability of curcumin, owing to its complexation with the hydrophilic polymers and further delineated the role of the hydrophobic nanofibrous network in regulating its release rate. The modified curcumin endowed the composites with antioxidant activities up to 5.7 times higher than that of free curcumin as well as promising anti-inflammatory and bacteriostatic activities. The cytocompatibility and cell proliferation capability on human dermal fibroblasts also evidenced the safe use of the constructs. Finally, the fabrics present pH-responsive color-changing behavior easily distinguishable within the pH range of 5-9. Thus, these designs offer a facile and cost-effective roadmap for the fabrication of smart multifunctional biomaterials, especially for chronic wound healing.

Research on the influence of surface crack development on radon exhalation in uranium tailing ponds under wet and dry cycles

Compacted soil layers effectively prevent the migration of radon gas from uranium tailings impoundments to the nearby environment. However, surface damage caused by wet and dry cycles (WDCs) weakens this phenomenon.In order to study the effect of crack network on radon exhalation under WDCs, a homemade uranium tailing pond model was developed to carry out radon exhalation tests under five WDCs. Based on image processing and morphological methods, the area, length, mean width and fractal dimension of the drying cracks were quantitatively analyzed, and multiple linear regression was used to establish the relationship between the geometric characteristics of the cracks and the radon exhalation rate under multiple WDCs. The results suggested that the radon release rate and crack network of the uranium tailings pond gradually stabilized as the water content decreased, following rapid development in a single WDC process. The radon release rate increased continuously after each cycle, with a cumulative increase of 25.9% over 5 cycles. The radon release rate and average crack width remained consistent in size, and a binary linear regression considering width and fractal dimension could explain the changes in radon release rate after multiple WDCs.

Construction of rGH/NTO 3D-network composite with improved energy release efficiency and significantly reduced corrosiveness of 3-nitro-1,2,4-triazole-5-one

3-Nitro-1,2,4-triazole-5-one (NTO) is a high-energy insensitive explosive with broad application prospects. However, due to the slow energy release kinetics, high decomposition temperature and unsatisfactory safety performance, its effective application is affected. In this paper, a reduced graphene oxide hydrogel (rGH)/NTO composite material was prepared to improve both the physical and chemical properties of NTO. The morphology and structure of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was found that the rGH/NTO composites did not undergo polymorphic transformation during the preparation process. At the same time, the three-dimensional (3D) network structure formed by rGH can reduce the initial temperature and activation energy of NTO thermal decomposition, and significantly increase the energy release rate. In addition, combined with experiments and DFT theoretical calculations, it is verified that the synergistic effect of the composite material reduces the corrosivity of NTO and increases the insensitivity, thereby improving the effective safety performance. Therefore, the synergistic effect of 3D network structure composite strategy is expected to be extended to the multi-performance control of energetic materials.

MgCa-Based Alloys Modified with Zn- and Ga-Doped CaP Coatings Lead to Controlled Degradation and Enhanced Bone Formation in a Sheep Cranium Defect Model.

Mg-based biodegradable metallic implants are gaining increased attraction for applications in orthopedics and dentistry. However, their current applications are hampered by their high rate of corrosion, degradation, and rapid release of ions and gas bubbles into the physiological medium. The aim of the present study is to investigate the osteogenic and angiogenic potential of coated Mg-based implants in a sheep cranial defect model. Although their osteogenic potential was studied to some extent, their potential to regenerate vascularized bone formation was not studied in detail. We have studied the potential of magnesium-calcium (MgCa)-based alloys modified with zinc (Zn)- or gallium (Ga)-doped calcium phosphate (CaP) coatings as a strategy to control their degradation rate while enhancing bone regeneration capacity. MgCa and its implants with CaP coatings (MgCa/CaP) as undoped or as doped with Zn or Ga (MgCa/CaP + Zn and MgCa/CaP + Ga, respectively) were implanted in bone defects created in the sheep cranium. MgCa implants degraded faster than the others at 4 weeks postop and the weight loss was ca. 50%, while it was ca. 15% for MgCa/CaP and <10% in the presence of Zn and Ga with CaP coating. Scanning electron microscopy (SEM) analysis of the implant surfaces also revealed that the MgCa implants had the largest degree of structural breakdown of all the groups. Radiological evaluation revealed that surface modification with CaP to the MgCa implants induced better bone regeneration within the defects as well as the enhancement of bone-implant surface integration. Bone volume (%) within the defect was ca. 25% in the case of MgCa/CaP + Ga, while it was around 15% for undoped MgCa group upon micro-CT evaluation. This >1.5-fold increase in bone regeneration for MgCa/CaP + Ga implant was also observed in the histopathological examination of the H&E- and Masson's trichrome-stained sections. Immunohistochemical analysis of the bone regeneration (antiosteopontin) and neovascularization (anti-CD31) at the defect sites revealed >2-fold increase in the expression of the markers in both Ga- and Zn-doped, CaP-coated implants. Zn-doped implants further presented low inflammatory reaction, notable bone regeneration, and neovascularization among all the implant groups. These findings indicated that Ga- and Zn-doped CaP coating is an important strategy to control the degradation rate as well as to achieve enhanced bone regeneration capacity of the implants made of Mg-based alloys.

Influence of structure parameters of pre-chamber on lean combustion of active pre-chamber jet ignition engine

Turbulent jet ignition (TJI) technology has the potential to improve engine efficiency. To elucidate the influence of different factors (diameter and number of holes) affecting the nozzle's total cross-sectional area, internal structure of the pre-chamber, and nozzle angle on the combustion characteristics of the engine. A 3 × 3 orthogonal test was designed and machined. The experiments were carried out on a pre-chamber single-cylinder engine.The results show that the pre-chamber's internal volume ratio has a great effect on the combustion characteristics in the cylinder. While the volume ratio of top of pre-chamber, transition region, and pre-chamber throat is 1:1:1, the engine's peak heat release rate is the highest. The highest Indicated thermal efficiency (ITE) can reach 43.43 %, with an absolute increase of 1.24 %, and the lean burn limit can reach λ = 2.6. Too large or too small nozzle angle will worsen the combustion state in the cylinder. The aperture and Nozzle number, which are the factors influencing the nozzle's total cross-sectional area, have different effects on the ignition delay, CA10-CA50, and CA50-CA90 of the engine. Various factors affecting the nozzle's total cross-sectional area have no apparent influence on the changing trend of ITE, but the aperture greatly influences ITE.

Predict Future Transient Fire Heat Release Rates Based on Fire Imagery and Deep Learning

The fire heat release rate (HRR) is a crucial parameter for describing the combustion process and its thermal effects. In recent years, some studies have employed fire scene images and deep learning algorithms to predict real-time fire HRR, which has led to the advancement of HRR prediction in terms of both lightweightness and real-time monitoring. Nevertheless, the development of an early-stage monitoring system for fires and the ability to predict future HRR based on current moment data represents a crucial foundation for evaluating the scale of indoor fires and enhancing the capacity to prevent and control such incidents. This paper proposes a deep learning model based on continuous fire scene images (containing both flame and smoke features) and their time-series information to predict the future transient fire HRR. The model (Att-BiLSTM) comprises three bi-directional long- and short-term memory (Bi-LSTM) layers and one attention layer. The model employs a bidirectional feature extraction approach, followed by the introduction of an attention mechanism to highlight the image features that have a critical impact on the prediction results. In this paper, a large-scale dataset is constructed by collecting 27,231 fire scene images with instantaneous HRR annotations from 40 different fire trials from the NIST database. The experimental results demonstrate that Att-BiLSTM is capable of effectively utilizing fire scene image features and temporal information to accurately predict future transient HRR, including those in high-brightness fire environments and complex fire source situations. The research presented in this paper offers novel insights and methodologies for fire monitoring and emergency response.