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Integrating phase change materials (PCM) into building walls can improve the thermal performance of walls. However, phase change walls (PCW) in hot climates have poor thermal performance during nighttime due to the exothermic process of PCM. In this work, we proposed a novel PCW integrating with interlayer ventilation (IVPCW), which is innovative for all-day availability. Its comprehensive performance analyses and optimization were conducted. The results indicate that utilizing interlayer ventilation improved the comprehensive performance of the PCW. Moreover, the optimal phase change temperature range is [28 °C, 34 °C], the optimal phase change layer thickness is 30 mm, the optimal air delivery method is method 2, and the optimal air layer thickness is 50 mm. The average daily cooling load of IVPCW with the optimal parameter was 126.08 kJ/m2 during the cooling-season week, which was 43.7 % lower than the pre-optimization. Long-term performance analyses conclude that IVPCW can effectively reduce the cooling load, electrical cost, and CO 2 emissions of air conditioning systems, which were 75.0 % lower compared with the ordinary wall (OW) and 59.1 % lower compared with PCW. In summary, IVPCW has a superior energy-saving and carbon-reducing performance to OW and PCW. This study established a theoretical foundation for the engineering implementation of IVPCW. [Display omitted] • The thermal performance of IVPCW under air-conditioning was investigated. • The weekly average DCL of IVPCW was 34.6 % lower than that of PCW. • The design parameters of IVPCW were optimized • The CO 2 emission reduction for IVPCW is 5.15 kgCO 2 /m2 in summer compared with PCW. [ABSTRACT FROM AUTHOR]

Wind-driven rain (WDR) is a significant contributor to indoor moisture in buildings, directly impacting the thermal and moisture performance of facades. Previous research on WDR in China focused on a limited number of low-rise pilot buildings, whose materials, shapes, and environmental settings are not entirely representative of typical applications. Aim to improve the accuracy of WDR predictions on low-rise building facades, there is a need for assessing different WDR calculation methods under various rain events. The paper presented high-resolution WDR measurements from a low-rise concrete building in Chongqing to investigate the distribution of WDR on building facades under local meteorological conditions. The study compared the performance of numerical simulations and two semi-empirical models with different meteorological data averaging techniques. The results indicated that Computational Fluid Dynamics (CFD) simulations using the Eulerian multiphase (EM) model more closely matched the actual catch ratio across various locations and the WDR amount across the facade, with errors ranging between 10%-25 % and 2%–23 %, respectively. Furthermore, the ISO model with weighted averaging (WA) technique outperformed others in estimating catch ratios at various locations and the WDR amount across the facade, particularly when estimating the midline catch ratio. When considering both cumuliform and stratiform rainfall, the arithmetic averaging (AA) technique was a viable method for the ASHRAE model to forecast WDR. The ISO model's predictions corresponded to 54%–81 % of the field measurements, while the ASHRAE model's estimates varied more widely, ranging from 33 % to 229 % of the measured values. • Field measurements of wind-driven rain are conducted on a low-rise building in chongqing. • Numerical simulations and semi-empirical models with averaging techniques are compared. • CFD simulations using Eulerian multiphase model accurately predict WDR distribution. • ISO model with weighted averaging technique outperforms in catch ratio prediction. • ASHRAE model with arithmetic averaging technique is viable for partial rain events. [ABSTRACT FROM AUTHOR]

• Reinfection defined as experienced more than two independent attacks regardless of subtypes • The median age at the first influenza virus infection was 4.5 (inter quartile range, 2.0–7.5) years • Reinfection was similar with influenza infection occurred in autumn and winter • The recurrent episode occurred 1.2–96.1 months between two consecutive onsets • No subtypes analysis due to the low number of laboratory-confirmed diagnoses Epidemiological characteristic profile of the reinfection of the influenza virus has not been well described. This study included all influenza cases of Guangxi, China from January 2011–December 2019 that were recorded in the National Notifiable Infectious Disease Reporting Information System (NIDRIS) within 24 hours after diagnosis. A total of 53,605.6 person-months and the median time of 8.7 months were observed for reinfection. The median age at the first influenza virus infection was 4.5 (interquartile range=2.0–7.5) years. The cumulative reinfection incidence was 2% at 6 months, 4% at 12 months, 5% at 24 months, and 7% after 59 months. Living in the rural area (hazard ratio [HR]=1.37 [95% confidence interval (CI), 1.29-1.45]), age ≤6 years (HR=11.43 [95% CI, 9.47–13.80]) were independent risk factors associated with influenza reinfection. Among 49 patients experiencing two laboratory tests, 32 patients (65.3%) were found to be infected with different virus types. The interval between two consecutive laboratory-confirmed episodes of the four groups differed (p =0.148): the maximum was 72.9 months and the minimum was 1.2 months. The reinfection of the influenza virus in Guangxi was independently and positively associated with living the rural area and younger age. The unusually high frequency of reinfection points to a need for further prospective longitudinal studies to better investigate the sufficient impact on different subtypes. [ABSTRACT FROM AUTHOR]

With climate change and urbanization, predicting the outdoor thermal environment of residential areas has become increasingly crucial, particularly during extreme weather conditions. Existing studies lack a comprehensive approach to optimizing temperature prediction algorithms for Chongqing and simulating extreme thermal environments at the neighborhood scale for future decades. This study employed various algorithms, including Levenberg-Marquardt optimization, Monte Carlo simulation, ARIMA modeling, and SARIMA prediction, to simulate and forecast temperature data for the central urban area of Chongqing from 2014 to 2023. By assessing metrics such as root mean square error (RMSE), R-squared (R2), and mean absolute percentage error (MAPE), the most effective prediction algorithm was identified. Results indicate that the Levenberg-Marquardt optimization algorithm, known for its nonlinear curve fitting capabilities, demonstrated superior performance in both the test and training sets, achieving an RMSE of 0.82 °C, MAPE of 1.81 %, and R2 of 0.75. This algorithm was subsequently used to forecast the outdoor temperature trend in Chongqing from 2024 to 2050, while also simulating the outdoor wind field, temperature distribution, building surface temperatures, and wind speeds in a residential district at neighborhood scale for 2030, 2040, and 2050 at a building density of 40 %. Findings reveal that peak pedestrian-level temperatures could reach 45.62 °C, and peak roof surface temperatures could reach 93.93 °C under extreme conditions. Furthermore, the study proposes practical recommendations for building layouts and cooling strategies. These findings are expected to improve residential planning in Chongqing, enhance residents' quality of life, and provide insights for other regions facing future temperature changes. • The Levenberg-Marquardt algorithm excels in forecasting temperatures in Chongqing. • Enclosed-layout buildings exhibit higher outdoor wind speeds at pedestrian height. • Taller buildings exhibit lower rooftop surface temperatures. • We advocate prioritizing enclosed building layouts in Chongqing. [ABSTRACT FROM AUTHOR]

Three inactive monovalent EV-A71 vaccines have been launched in China since 2016, which may change the HFMD pathogen spectrum and epidemiological trend. Using notifications from the national surveillance system, we analyzed the epidemiological character profiles and the possible pathogen replacement. The proportion of HFMD cases aged 0–12 months decreased from 23.0% to 15.3% between 2013–2015 and 2017–2019 (p < 0.01). EV-A71 among laboratory-confirmed severe cases in 2013–2015 (62.8%) transformed to other EVs (67.2%) in 2017–2019. The age distribution of EV-A71 infection shifted to the older. The cumulative coverage of the EV-A71 vaccine for children aged six months to five years in Guangxi has increased, while in severe cases, the positive rate declined. After gradually expanded vaccination, EV-A71 associated incidence rate, case-severity rate has decreased, and other serotypes are becoming dominant. Thus, bivalent even polyvalent vaccines are urgently needed to control HFMD. [ABSTRACT FROM AUTHOR]

Strengthening the thermal performance of building envelopes is an important direction towards achieving energy efficiency. This paper investigated the thermal performance and energy-saving effect of phase change material (PCM) cool roofs in office buildings during the summer season in Chongqing, leveraging a combination of measurement and simulation techniques. Compared to ordinary and PCM roofs, the PCM cool roof exhibited improved thermal performance, indoor thermal environment, and enhanced building energy savings. Results showed that the inner wall temperature of the PCM cool roof was 6.3 °C lower than that of an ordinary roof, and had a cooling range 65.1% higher than that of a PCM roof. Through computational fluid dynamics (CFD) simulations, this study analyzed the influence of five parameters on the thermal performance and latent heat utilization of the PCM cool roof. Finally, the energy-saving potential and economic benefits of using PCM cool roof in an office building in Chongqing were simulated. This study is helpful to the popularization and application of PCM cool roof. • The thermal performance and energy-saving potential of PCM cool roof are explored. • In summer, the daily energy saving of PCM cool roof ranges from 5.1% to 13.5%. • Analyzed the influencing factors and significance of the roof thermal performance. • The energy saving of PCM cool roof used in office buildings in summer is 6437 kW h. • The CO 2 emission reduction of PCM cool roof is 4115.8 kg/y. [ABSTRACT FROM AUTHOR]

• Both viral load in upper respiratory tract and positive rate of exhaled breath condensate from Omicron BA.2 subvariant patients were higher than those from BA.1 subvariant patients. • The patients with Omicron BA.1 or BA.2 subvariant infection had the same level of virus breath emission rate, and the growth rate of BA.1 and BA.2 subvariants are similar in Caco2 cells. • The viral load in upper respiratory tract and the virus breath emission rate of Omicron patients had the similar variation trend. [ABSTRACT FROM AUTHOR]

• At the early (1–5 days) and middle (6–10 days) stages after the onset of COVID-19 symptom, Omicron variant patients exhaled ten million virus particles per hour. • In the late stage (11–19 days), the breath emission rate was still as high as those of the two other stages. • Omicron variant may be highly transmissible. [ABSTRACT FROM AUTHOR]

Hand, foot, and mouth disease (HFMD) caused by enterovirus A71 (EV-A71) is a major public health issue in China that poses severe risks to children's health, especially those under the age of 3. Since 2016, EV71 vaccines developed by three Chinese manufacturers have been approved for use, and clinical trials of these vaccines have demonstrated protection against EV-A71 infection. However, few studies have assessed the effectiveness of these vaccines in real-world settings. A test-negative design case-control study was used to estimate vaccine effectiveness (VE) in cases of severe HFMD. We obtained information including EV-A71 vaccination status from the Local Center for Disease Control and Prevention (CDC) on all severe HFMD cases under 12 years in age in Guangxi, China, from Jan. 1, 2017, to Dec. 31, 2018. Enterovirus infection was laboratory confirmed by local CDCs. Individuals with a positive EV-A71 nucleic acid test result were assigned to the case group, and those with negative EV-A71 nucleic acid test results were assigned to the control group. We estimated VE using logistic regression. A total of 2779 severe HFMD cases were enrolled in the study; 838 children were EV-A71 positive cases, and 1941 children were EV-A71 negative controls. The proportion of EV-A71 positive cases aged 6–36 months was lower than that for EV-A71 negative controls. EV-A71 infection was associated with an increased risk of mortality (aOR, 8.8; 95% CI, 1.3–61.6). The adjusted VE was 81.4% and 88.3% for one dose and two doses, respectively. Our findings suggest that the rate of EV-A71 has fallen among severe HFMD cases in Guangxi and that the risk for EV-A71 infection in 6–36-month-old children has been reduced by use of the vaccine. Inactivated vaccines performed well in severe HFMD cases in a real-world setting. [ABSTRACT FROM AUTHOR]

The high stability and low cost are considered comparative advantages of the SrTiO 3 chalcogenide oxide thermoelectric material. However, the pure SrTiO 3 material is characterized by low electrical conductivity and high thermal conductivity, which could eventually lead to poor overall thermoelectric performance, and limit its application in the field of high temperature thermoelectricity. The development of composite-based metal materials with SrTiO 3 by using suitable methods is arising as the most promising approach to improve their electrical properties. Along these lines, in this work, xNb: (1-x) SrTiO 3 composite ceramics were successfully synthesized by using the high temperature and high-pressure (HPHT) method. The Nb powder was oxidized into various niobium oxides exhibiting their own thermoelectric properties under HPHT conditions to optimize the thermoelectric properties of the Nb/SrTiO 3 composites. From our analysis, it was demonstrated that with the increase of the Nb powder content, the electrical properties were significantly improved. In addition, the fabricated Nb/SrTiO 3 composite ceramics possessed a special "pore" microstructure, which significantly reduced the thermal conductivity of the material. In this work, the physical phase, microscopic morphology, and thermoelectric properties of the synthesized samples were also systematically tested and analyzed, and the maximum zT value of 0.28@973 K was obtained for the final sample with x = 0.4. The implementation of the HPHT method for the preparation of chalcogenide oxide composite ceramics provides valuable insights for the improvement of their thermoelectric properties. [ABSTRACT FROM AUTHOR]

Acute severe hepatitis with unknown aetiology in children (ASHep-UA) has become a global health alert. This article reported clinicopathological characteristics of 3 probable ASHep-UA cases. We respectively collected serological data and liver biopsies of 3 suspected cases of ASHep-UA. Neutralizing antibodies titer for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variants were determined by virus neutralization test (VNT). Histological assessment, immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) for cytomegalovirus (CMV), Epstein-Barr virus (EBV), human adenoviruses (HAdV), adeno-associated virus (AAV2), human herpes virus type 6 (HHV-6) were performed to identify possible aetiologies. Remarkable elevation of transaminase (median ALT level, 1100 IU/liter; median AST level, 500 IU/liter) were revealed with undetectable hepatitis A-E and non-hepatotropic virus in both sera and tissues. Weakness, jaundice, pale stools and splenomegaly were observed. Interestingly, two individuals had SARS-CoV-2 Omicron variants infection. Histologically, moderate or severe lobular necroinflammation, active interface hepatitis and portal inflammatory infiltrate with lymphocytic, plasma cells, neutrophils and eosinophilic cells were noted. The exact aetiology of ASHep-UA was still unknown. By reporting the 3 probable cases, we expect to enrich the clinical experience in diagnosis and treatment of ASHep-UA as well as the pathological characteristics. • We analyzed the pathological characteristics of 3 suspected patients. • Neutralizing antibodies titer for SARS-CoV-2 Omicron variants were determined. • This article thoroughly discussed the possible causes of ASHep-UA. [ABSTRACT FROM AUTHOR]

• PCMC roof analyzed for thermal performance via experiments and numerical analysis. • PCMC room saved an average of 1.14kW·h/day, with an energy saving rate of 14.78%. • PCMC room's energy-saving effect lower on cloudy/rainy days but still maintained. • Strong linear correlation between external roof temperature and solar radiation. Cool roofs can reduce building energy consumption and improve indoor and outdoor thermal environments. A phase change material cool roof (PCMC roof) was proposed in order to reduce roof heat gain in the indoor thermal environment in summer. Indoor thermal and energy environmental parameters in three full-size rooms (ordinary room, PCM room, and PCMC room) were tested from July to September 2022. The heat transfer characteristics and energy saving effect of roofs were investigated by combining experimental analysis with numerical analysis. Compared with the ordinary roof, the PCMC roof decreased external and internal roof surface real-time temperatures up to 30.0 °C and 6.4 °C respectively, and reduced the roof inner surface heat flux of 33.3%-66.7%. Compared with the relevant roof studies, the energy saving and cooling effects are more significant. Then, based on the mathematical model of roof heat transfer, the correlation analysis between seven different elements was carried out to evaluate the energy-saving effect of PCMC roof. This study investigates the PCMC roof from the aspects of roof heat transfer characteristics, influence on indoor thermal environment, energy saving evaluation, etc., which provides a more complete and valuable reference for advancing building roofs. [ABSTRACT FROM AUTHOR]

Abstract Brain-derived neurotrophic factor (BDNF), a critical modulator in the neurodevelopment and maintenance of both central and peripheral nervous systems, is regarded as a potential therapeutic target of Parkinson's disease (PD). However, its association with PD remains unclear and the data are inconsistent. To explore the correlation, studies reporting BDNF levels in PD patients and healthy controls are searched and a sample of 1496 participants are pooled in the meta-analysis, demonstrating significantly decreased serum levels of BDNF in PD patients when compared with the healthy controls (SMD = −1.03; 95% CI [−1.83, −0.23]; P =.012). Meta-regression analysis indicates gender is an important confounding factor (Adj R2 = 69.20%, p =.004, I2 res = 90.64%), whereas age (Adj R2 = 11.91%, P =.95, I2 res = 96.86%), H-Y stages of PD progression (Adj R2 = −30.18%, P =.612, I2 res = 96.62%) and MoCA score assessed cognitive impairment (Adj R2 = 2.18%, P =.517, I2 res = 64.41%) show few moderating effects. The research provides evidence of moderate quality that blood levels of BDNF are decreased in PD patients despite various influencing factors, supporting an association between decreased level of peripheral BDNF and PD. Highlights • Serum level of BDNF declines in PD patients. • Gender affects peripheral BDNF decline in PD patients. • Age and disease severity do not affect peripheral BDNF decline in PD patients. [ABSTRACT FROM AUTHOR]

• Renewable sources have been used to improve the fire performance of PA66. • PA66 composite had good flame retardant and anti-dripping performance. • The generated ammonia of FR-PA66 decreased by 69.4% than pure PA66. • Vegetable tanning was expanded to prepare flame retardant and anti-dripping PA66. Vegetable tanning is an ancient process that uses polyphenols to transform animal hides and pelts into durable and structurally stable leather. Inspired by this, polyamide 66 (PA66) and keratin (Ker) were blended to fabricate a PA66 composite (PA66/Ker) by solution casting, which was then tanned to prepare flame retardant and anti-dripping PA66/Ker composite (FR-PA66). The results indicated that the peak of heat release rate (PHRR) and total heat release (THR) of FR-PA66 decreased by 75.3% and 38.4%, respectively. The limiting oxygen index (LOI) of FR-PA66 reached 29.65% and a UL-94 V-0 rating was obtained. In addition, the char residue of FR-PA66 was 21.6% at 800 °C under N 2 atmosphere, indicating good char-forming ability. This work provides a new idea by using renewable biomass keratin and tannin to endow PA66 with flame retardant and anti-dripping performance. The preparation process is simple and feasible, suitable for large-scale preparation. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] The prediction of chemotherapeutic sensitivity is important in cancer treatment. [•] False positive genes seriously impact the performance of predictive models. [•] We proposed a combined strategy for optimizing the selection of candidate genes. [•] The performance of predictive models is improved when using the refined genes. [•] This research will benefit the guidance of the personalized chemotherapy. [Copyright &y& Elsevier]

[Display omitted] • The effect of microhabitat factors on regeneration was studied in Chinese pine plantation. • Soil chemical properties were the major microhabitat factors affecting the Chinese pine regeneration. • Sapling stage is the critical period in the regeneration process of Chinese pine plantation. • B. platyphylla and Q. liaotungensis may become canopy replacement species in stand succession. Chinese pine (Pinus tabuliformis) is one of the main tree species for water and soil conservation on the Loess Plateau. However, most of these plantations face a series of ecological problems, such as low diversity of understory plants and difficulty in natural regeneration. Our study focused on the microhabitat factors that affected the species composition of understory woody plants and the distribution and growth of regeneration in Chinese pine plantations. Plots of 50 × 50 m were randomly established in three typical mature plantations, and then each plot was divided into 100 5 × 5 m microplots to investigate the characteristics of canopy trees, Chinese pine regeneration, other understory woody plants, the light environment, litter and soil. The involved microhabitat factors jointly explained 37.68% of the variation in the species composition of understory woody plants, among which soil total phosphorus (2.66%) and available potassium (2.19%) were the main factors. In the regeneration layer, Chinese pine regeneration (7,261 stems·ha−1, 124.6 cm), Quercus liaotungensis (3,114 stems·ha−1, 117.0 cm) and Betula platyphylla (953 stems·ha−1, 305.7 cm) were considered the canopy replacement species with the most potential. Additionally, we found that the regeneration density was significantly affected by soil total nitrogen, available potassium and shrub density, while the differences in regeneration height growth mainly resulted from the density of other understory trees and shrubs, soil total phosphorus and diffuse non-interceptance. The density of saplings and juvenile trees of Chinese pine was more affected by microhabitat factors than that of seedlings, but the effect of the microenvironment on the former two was less different, indicating that the sapling stage may be the critical period for successful recruitment of the plantations. Therefore, gap creation or thinning is suggested to promote the growth of saplings and juvenile trees, thus increasing the opportunity for them to enter the canopy. At the stand scale, soil resources and interspecies interactions were the dominant microhabitat factors influencing the regeneration of Chinese pine, which inspired us to deeply explore the vegetation-soil-microbial systems and the relationship between regeneration and their neighbors in the future. Moreover, managers should pay more attention to the survival and growth of saplings and juvenile trees to promote the sustainable development of Chinese pine plantations. We believe that these plantations will be transformed into coniferous and broad-leaved mixed forests with high stability and species diversity (e.g., P. tabuliformis × B. platyphylla or P. tabuliformis × Q. liaotungensis). [ABSTRACT FROM AUTHOR]

Abstract: To develop novel expressed sequence tags-simple sequence repeats (EST-SSR) markers in radish, a taproot cDNA library was constructed. A total of 10,052 clones from the cDNA library were sequenced and a large number of high quality ESTs was generated. Among these ESTs, a set of 179 SSRs, distributing in 176 unigene sequences, were detected, of which, 50.84% were di-nucleotide, followed by tri- (29.61%), hexa- (9.49%), penta- (6.15%) and tetra-nucleotide (3.91%) repeats, respectively. GA/TC (25.69%) was the most frequent repeat type of all repeat types. Out of 125 primer pairs designed, 110 (88%) could generate unambiguous amplification products. Totally 28 EST-SSR primer pairs were selected for genetic diversity analysis in 32 radish genotypes. It was found that two to seven alleles could be detected with a mean of 3.5 per primer pair and the polymorphism information content (PIC) values of these primers ranged from 0.000 to 0.825 with an average of 0.500. The genotype data were analyzed with NTSYS-pc software, which grouped the 32 accessions into three main clusters at the similarity index value of 0.60, which was mainly in accordance with the different biological characterizations of the accessions. In addition, the 28 EST-SSR primer pairs were further used to test the transferability on 12 accessions from three genera of Raphanus, Brassica and Arabidopsis in Brassicaceae. The results showed that 18 primer pairs (64.2%) could produce target PCR bands in the 12 accessions. The EST-SSR markers developed herein represented a valuable resource for the genetic diversity analysis, genetic mapping and marker-assisted selection in radish. [Copyright &y& Elsevier]

In this study, a microencapsulated phase change material (MPCM) was mixed with a composite phase change material (CPCM) made of porous silica/paraffin to produce hybrid PCMs (C-MPCM), and then prepared two types of gypsum-based PCM wallboards (model A, which is M-A for short henceforth: Split; and model B, which is M − B for short henceforth: Hybrid). After that the physical properties and microstructure of the samples were evaluated. The results showed that paraffin wax was well immersed in porous silica with an optimal adsorption rate of 70% with no leakage. Meanwhile, the CPCM maintained good chemical compatibility and thermal stability. In addition, the thermal properties of PCM wallboards and gypsum wallboard were studied through an automatically controlled test system. Thermal performance showed that, both the M-A/B wallboards were able to keep the temperatures of room A/B within the thermal comfort range throughout the year. M-A wallboard was more energy efficient than M − B wallboard in summer working conditions; M − B wallboard was more energy efficient in winter working conditions. The total water supply duration consumed by M − B wallboard was far less than that of M-A wallboard. Considering comprehensively, M − B wallboard is more suitable for practical application in building energy saving. • A new type of hybrid PCM (C-MPCM) was prepared. • An active non-load-bearing partition PCM wallboard was invented. • A system was developed to test the thermal performance of wallboards. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we first investigate some basic properties of remotely almost periodic functions and then show the existence and uniqueness of remotely almost periodic solutions to systems of differential equations with piecewise constant argument. [Copyright &y& Elsevier]

• The mean value of leaf nitrogen (N): phosphorus (P) is significantly less than 14. • Leaf N concentration is less affected by the environmental variables. • Leaf N:P ratio decreases with increasing P resorption efficiency. Plant growth and vegetation productivity were generally limited either by nitrogen (N) or phosphorus (P) worldwide. To date, our current understandings on plant nutrient limitation are primarily derived from site-specific studies. By taking account into more factors, studies on regional or larger scales might resolve the divergences effectively arisen from regional differences, which would help provide new insights for plant nutrient limitation. In this study, we made an attempt to evidence the particular element that limiting the growth of Cunninghamia lanceolata (Chinese fir) based on a regional investigation. Firstly, we found that leaf N:P ratio (11.49) was significantly lower than 14, which suggested and evidenced that the growth of Chinese fir was limited by N. Next, leaf N concentration was less affected by the environmental variables, showing low variability. Leaf P concentration and N:P ratio were significantly affected by soil P concentration (SP), mean annual temperature (MAT) and altitude (ALT), and both of them showed high variability. Hence under same regional environmental changes, the level of the variability in leaf N or P concentration might affect the N or P supply for plant growth. Thirdly, the P resorption efficiency (PRE) was significantly higher than N resorption efficiency (NRE). Leaf N:P ratio decreased with the increasing PRE and |NRE − PRE|. Overall, our findings suggested that in subtropical China, low leaf N:P ratios, low N variability under, and high PRE were three major pieces of evidence that induce N- limitation for the growth of Chinese fir. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biomass-based ammonium phytate (AP) enhanced the cyclization of PAN fibers. • The cyclic conjugate structure improved the flame retardancy and charring of PAN fibers. • Phosphorus element was introduced into PAN fibers during the thermal oxidation. • PAN fibers treated with AP and thermal oxidation had durable flame retardancy. To address the flammable shortcoming of polyacrylonitrile (PAN) fibers, an ammonium phytate (AP) flame retardant was fabricated by using biomass phytic acid (PA) and urea as raw materials. PAN fibers were firstly treated with AP aqueous solution, which were then thermally oxidized to gain durable flame retardant PAN fibers (O-AP-PAN). The structure of fibers was characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The results indicated that AP promoted the formation of a thermally stable cyclic conjugated structure, and the P element was incorporated into the PAN fibers through covalent bond. The limiting oxygen index (LOI) value of O-AP-PAN fibers improved from 17.0% of PAN fibers to 36.6%. Even after 50 laundering cycles, the LOI value of O-AP-PAN maintained as high as 30.5%, indicating exceptional washing durability. Additionally, the total heat release and heat release capacity of O-AP-PAN were reduced by 46.8% and 52.7%, respectively. Besides, the mechanical strength of O-AP-PAN was well maintained without affecting practical use. In this work, a simple and feasible durable flame retardant strategy for PAN fibers was established, which was convenient for large-scale preparation of flame retardant PAN fibers. [ABSTRACT FROM AUTHOR]

• A surface modification strategy was developed to fabricate flame retardant PAN fibers. • PAN fibers have good flame retardancy and increased mechanical properties. • The modification process is suitable for large-scale preparation. To improve the flame retardancy of polyacrylonitrile (PAN) fibers, PAN fibers were firstly modified through amination with diethylenetriamine (DETA) to obtain ammoniated PAN fibers (A-PAN). Then, A-PAN underwent phosphorylation modification via phosphorus-containing flame retardant, i.e., tetrakis (hydroxymethyl) phosphonium sulfate (THPS) to fabricate flame retardant PAN fibers (THPS-A-PAN). XPS and FTIR confirmed the covalent bonding of DETA and THPS with PAN fibers. TGA showed improved thermal stability, particularly in increased char residue at high temperatures. The modified PAN fibers exhibited enhanced flame retardancy in vertical burning tests and MCC analysis, with LOI values increasing from 17% to 32.5% and maintaining at 26.5% after 30 laundering cycles (LCs). Fire safety parameters such as heat release capacity (HRC), total heat release (THR), and the fire growth index (FGI) decreased by 51.5%, 46.9%, and 41.9%, respectively. In addition, the tensile strength and elongation at break of THPS-A-PAN increased from 2.69 cN/dtex and 28.6% to 3.08 cN/dtex and 30.1% respectively, indicating enhanced mechanical properties. This work develops a feasible strategy to improve the flame retardancy of PAN fibers while endowing them with reinforced mechanical properties, which provides a possible research direction for the practical application of flame retardant PAN fibers. [ABSTRACT FROM AUTHOR]

To develop green and efficient polyacrylonitrile (PAN) fibers with excellent fire safety properties, a new biomass-based flame retardant (PPC@VA) with vinyl-terminated groups was prepared based on the reaction of hexachlorocyclotriphosphonitrile, teat polyphenols, ethylenediamine and vinylphosphonic acid. Subsequently, it was mixed with spinning solution to obtain PPC@VA/PAN through wet spinning, which were then chemically cross-linked via thermal initiation to achieve CC-PPC@VA/PAN fibers. CC-PPC@VA/PAN showed a significant improvement in flame retardancy with a limiting oxygen index value of 32.5 %. The peak of smoke production rate, total smoke production and CO production rate were lowered by 81.9 %, 77.8 % and 91.3 %. Besides, the hazardous gas HCN was greatly suppressed. Owing to the macromolecular entanglement, hydrogen bonding and covalent cross-linking, CC-PPC@VA/PAN improved elongation at break and tensile strength by 19.2 % and 72.1 %. Also, chemical cross-linking contributed to decrease the migration of P/N-based flame retardants, lower the potential risk of water eutrophication and increased the service life of the fibers. [Display omitted] • A novel biomass-based flame retardant PPC@VA with terminal vinyl groups was prepared. • PPC@VA endowed PAN fibers with good flame retardant and smoke suppression properties. • Flame retardant PAN composite fibers had reinforced mechanical properties. • Chemical crosslinking extends the service life of flame retardant PAN composite fibers. [ABSTRACT FROM AUTHOR]