Rigid polyurethane foam/aluminum diethylphosphinate (RUPF/ADP) composites were prepared by one-step water-blown method. Furthermore, scanning electron microscope (SEM), thermal conductivity meter, ...thermogravimetric analysis (TGA), limiting oxygen index, Underwriters Laboratories vertical burning test (UL-94) and microsacle combustion calorimetry were applied to investigate thermal conductivity, thermal stability, flame retardancy and combustion behavior of RPUF/ADP composites. Thermogravimetric analysis–Fourier transform infrared spectroscopy (TG–FTIR) was introduced to investigate gaseous products in degradation process of RPUF/ADP composites, while SEM and X-ray photoelectron spectroscopy were used to research char residue of the composites. It was confirmed that RPUF/ADP composites presented well cell structure with density of 53.1–59.0 kg m
−3
and thermal conductivity of 0.0425–0.0468 W m
−1
K
−1
, indicating excellent insulation performance of the composites. Flame retardant test showed that ADP significantly enhanced flame retardancy of RPUF/ADP composites, RPUF/ADP30 passed UL-94 V-1 rating with LOI of 23.0 vol%. MCC test showed that ADP could significantly decrease peak of heat release rate (PHPR) of RPUF/ADP composites. PHPR value of RPUF/ADP20 was decreased to 158 W g
−1
, which was 21.8% reduced compared with that of pure RPUF. TG–FTIR test revealed that the addition of ADP promoted the release of CO
2
, hydrocarbons and isocyanate compound in first-step degradation of RPUF matrix while inhibited the release of CO in second step degradation. Char residue analysis showed that the addition of ADP promoted polyurethane molecular chain to form aromatic and aromatic heterocyclic structure, enhancing strength and compactness of the char. This work associated a gas–solid flame retardancy mechanism with the incorporation of ADP, which presented an effective strategy for preparation of flame retardant RPUF composites.
Our study aimed to explore the function and mechanism of action of long noncoding RNA (lncRNA) SRY-Box 21 antisense RNA 1 (SOX21-AS1) in amyloid beta
25–35
(Aβ
25–35
)-induced neuronal damage. To ...induce neuronal damage, neuronal cells and differentiated IMR-32 neuroblastoma cells were challenged by Aβ
25–35
. SOX21-AS1 and miR-132 quantities were detected by quantitative reverse transcription polymerase chain reaction. Cell damage was evaluated by detecting the changes of cell viability, apoptosis, and oxidative stress. Cell viability was measured using cell counting kit-8. Cell apoptosis was evaluated by flow cytometry and caspase-3 activity. The oxidative stress was analyzed by reactive oxygen species level. The expression of proteins associated with the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway was examined by western blot. SOX21-AS1 abundance was up-regulated in Aβ
25–35
-challenged neuronal cells. Silencing of SOX21-AS1 attenuated Aβ
25–35
-induced viability reduction and promotion of apoptosis and oxidative stress, suggesting that silencing of SOX21-AS1 repressed Aβ
25–35
-induced neuronal damage. miR-132 quantity was reduced in Aβ
25–35
-challenged neuronal cells, and negatively controlled by SOX21-AS1. miR-132 knockdown abolished the effect of SOX21-AS1 silencing on Aβ
25–35
-induced neuronal damage, indicating that SOX21-AS1 controls Aβ
25–35
-induced neuronal damage via regulating miR-132. The PI3K/AKT signaling was repressed in Aβ
25–35
-challenged cells, but this effect was counteracted upon overexpression of miR-132. In conclusion, SOX21-AS1 knockdown mitigated Aβ
25–35
-dependent neuronal cell damage by promoting miR-132/PI3K/AKT pathway.
Melamine–formaldehyde resin-microencapsulated ammonium polyphosphate (MFAPP) was prepared by in situ polymerization using melamine–formaldehyde (MF) resin as the shell material. MFAPP was ...characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), which confirmed its successful fabrication. MFAPP was further introduced to prepare rigid polyurethane foam/microencapsulated ammonium polyphosphate composites (RPUF/MFAPP). The flame retardancy, water resistance, physical properties, and thermal stability of RPUF/MFAPP were compared with virgin RPUF and RPUF/APP composite. RPUF/MFAPP30 possessed excellent flame retardancy. Even after immersion in water for 15 days, RPUF/MFAPP30 achieved V-1 rating in UL-94 test with limiting oxygen index (LOI) of 21.3 vol%, which was better than that of RPUF/APP30 with equivalent APP loading. The compressive strength of RPUF/MFAPP30 was 0.295 MPa, which was 13.5% higher than that of RPUF/APP30. Thermogravimetric analysis-Fourier transform infrared spectroscopy (TGA-FTIR) was applied to investigate gaseous products of the decomposition process for RPUF/APP and RPUF/MFAPP. It was found that the intensities of CO
2
, isocyanate compounds, and CO for RPUF/MFAPP were lower than the values for RPUF/APP, indicating superior fire safety of RPUF/MFAPP. SEM and Raman spectra confirmed that RPUF/MFAPP30 possessed more compact char residue with higher thermal resistance, which was thus better able to inhibit mass and heat transmission in combustion. Consequently, a possible gas–solid flame-retardant mechanism of the RPUF/MFAPP composite was proposed.
Microencapsulated ammonium polyphosphate (SiAPP) was prepared by sol-gel method with gel-silica as the shell material. And also, SiAPP was characterized by X-ray photoelectron spectroscopy (XPS), ...Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), which confirmed the successfully fabrication of SiAPP. Furthermore, 30 php (parts per hundreds of polyol) SiAPP was introduced to prepare rigid polyurethane foam/microcapsulated ammonium polyphosphate composites (RPUF/SiAPP30). Flame retardancy, water resistance, physical properties and thermal stability of RPUF/SiAPP composites were compared with virgin RPUF and RPUF/APP composites. The results showed that RPUF/SiAPP30 which possessed excellent flame retardancy. Even after being immersed in water for 15 days, the underwriters laboratories vertical burning test (UL-94) of RPUF/SiAPP30 could pass V-1 rating with the limiting oxygen index (LOI) of 21.8 vol%, which was better that of RPUF/APP30. Compressive strength of RPUF/SiAPP30 was 0.292 MPa, which was 12.3% higher that of RPUF/APP30. SEM and Raman spectra confirmed that RPUF/SiAPP30 possessed more compact char residue with higher thermal resistance, which could inhibit mass and heat transmission in combustion. Consequently, a possible gas-solid flame-retardant mechanism of RPUF/SiAPP composite was proposed.
Highlights
Gel-silica microencapsulated ammonium polyphosphate (SiAPP) was introduced into RPUF composites in the first time.
SiAPP could significantly enhance water resistance, mechanical properties as well as flame retardancy of RPUF/SiAPP composites.
RPUF/ SIAPP has excellent thermal insulation properties.
While Portland cement produces large amounts of carbon dioxide, low-calcium high-strength cements effectively reduce carbon emissions by decreasing the proportion of high-calcium minerals. In order ...to enhance the practical application value of low-calcium high-strength cement, the effects of mineral admixtures on the chloride binding capacity and pore structure characteristics of low-calcium high-strength cement pastes were investigated by equilibrium method and mercury intrusion method. The results showed that the chloride binding capacity of low-calcium high-strength cement pastes is superior to that of Portland cement. Fly ash and slag enhance this capacity by promoting monosulfoaluminate and C-S-H gel formation, with fly ash being more effective. Ground limestone also boosts chloride binding when incorporated at less than 10 wt%. However, sulfates have a more significant negative impact on chloride binding capacity in low-calcium high-strength cement pastes compared to Portland cement. The porosity of low-calcium high-strength cement pastes exhibits contrasting trends with the addition of fly ash, ground limestone, and slag. Fly ash and limestone initially coarsen the pore structure but later facilitate the transition of larger pores to smaller ones. In contrast, slag initially has little impact but later promotes the conversion of large capillary pores to medium ones, optimizing the pore structure. Notably, above 10 wt% fly ash, the critical pore diameter decreases with additional fly ash except at 10% where it increases for 3 days. Ground limestone enlarges the critical pore diameter, and this effect intensifies with higher content. During early hydration, slag decreases the critical pore diameter, but its impact diminishes in later stages.
A phosphine oxide-containing bio-based curing agent was synthesized by addition reaction between furan derivatives and diphenylphosphine oxide. The molecular structure of the as-prepared bio-based ...curing agent was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Dynamic mechanical analysis results indicated that with the increase of bio-based curing agent content, the glass transition temperature of epoxy/bio-based curing agent composites decreased, which was related to the steric effect of diphenylphosphine oxide species that possibly hinder the curing reaction as well as the reduction in the cross-linking density by mono-functional N-H. By the addition of 7.5 wt-% bio-based curing agent, the resulting epoxy composite achieved UL-94 V-0 rating, in addition to limiting oxygen index of 32.0 vol-%. With the increase of content for the bio-based curing agent, the peak of heat release rate and total heat release of the composites gradually decreased. The bio-based curing agent promoted the carbonization of the epoxy matrix, leading to higher char yield with good thermal resistance. The high-quality char layer served as an effective barrier to retard the diffusion of decomposition volatiles and oxygen between molten polymers and the flame. This study provides a renewable strategy for fabricating flame retardant and transparent epoxy thermoset.
Walls of buildings fitted with functional materials are beneficial for saving energy and increasing the comfort level. The Ce–Eu/TiO
2
phase change material mixed with gypsum as wall plaster ...materials could purify indoor air, store heat energy, and also control air humidity. This paper studied the thermal-photocatalytic-humidity performance of gypsum based functional materials for residential walls and evaluated the effects of its application. The latent heat of gypsum based functional materials was 23.57 J/g, whereas the phase transition temperature of 16.81–24.97 °C, which was a comfortable temperature range for humans. After 11 h of testing the formaldehyde concentration decreased from 1.0 to 0.3144 mg m
−3
and the degradation rate reached 68%. The maximum temperature difference between the experiment room and the contrast room could reach 3.9 °C. The relative humidity indoors of the experiment room was 38.40–62.30%, which was much more stable than that of the contrast room.
Graphic Abstract
The deformation and cracking of concrete will lead to various deterioration processes, which will greatly reduce the durability and service life of the concrete pavement. The relating previous ...studies and analysis revealed that the coupling action of environmental temperature, moisture, and wheel load will cause cracking and seriously affect the normal service and durability of pavement concrete. This paper presents theoretical and numerical state-of-the-art information in the field of deformation and failure of pavement concrete under coupling action of moisture, temperature, and wheel load and draws some conclusions. (a) Concrete is a typical porous material, moisture and heat transfer theory has obtained enough data to simulate the hygro-thermo properties of concrete, and the relationship between moisture and heat is very clear. (b) There are few studies on concrete pavement or airport pavement considering the coupling action of moisture, temperature, and wheel load. (c) Concrete pavement is subjected to hygro-thermal-mechanical coupling action in service, which has the characteristics of a similar period and its possible fatigue effect. (d) COMSOL software has certain advantages for solving the coupled hygro-thermal-mechanical of concrete.
Federated learning (FL) provides convenience for cross-domain machine learning applications and has been widely studied. However, the original FL is still vulnerable to poisoning and inference ...attacks, which will hinder the landing application of FL. Therefore, it is essential to design a trustworthy federation learning (TFL) to eliminate users’ anxiety. In this paper, we aim to provide a well-researched picture of the security and privacy issues in FL that can bridge the gap to TFL. Firstly, we define the desired goals and critical requirements of TFL, observe the FL model from the perspective of the adversaries and extrapolate the roles and capabilities of potential adversaries backward. Subsequently, we summarize the current mainstream attack and defense means and analyze the characteristics of the different methods. Based on a priori knowledge, we propose directions for realizing the future of TFL that deserve attention.
Cracks caused by environmental temperature and humidity variation are generally considered one of the most important factors causing durability deterioration of concrete structures. The seasonal or ...daily variation of ambient temperature and humidity can be considered periodic. The dynamic modulus of elasticity is an important parameter used to evaluate the performance of structural concrete under periodic loads. Hence, in this paper, the dynamic elastic modulus test of concrete under simulating periodic temperature-humidity variation is carried out according to monthly meteorological data of representative areas (Nanjing, China). The dynamic elastic modulus attenuation pattern and a dynamic elastic modulus degradation model of concrete under periodic temperature-humidity are investigated. The test results show that the dynamic elastic modulus of concrete decreases and tends to be stable under the action of periodic temperature-humidity. Comparative analysis shows that the two-parameter dynamic elastic modulus degradation model is more suitable for describing the dynamic elastic modulus attenuation pattern of concrete under periodic temperature-humidity action than the single-parameter one.
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