Index Meter Research Articles

The Effect of the Proportion of Rubber Components on the Properties of EVA/SBR/BR Foams

In actual production processes, pure ethyl vinyl acetate (EVA) foams have a high shrinkage rate, and the foaming matrix is prone to plastic deformation, even causing the collapse of bubbles. This limits the further application of EVA foams. In this study, we incorporated styrene butadiene rubber (SBR) and butadiene rubber (BR) into EVA to improve the mechanical properties and dimensional stability of EVA composite foams without sacrificing their low-density characteristics of low density. We used a melting index meter, rotorless vulcanizing meter and dynamic mechanical analysis (DMA) to characterize the changes in viscosity and energy storage modulus of the composite matrix. Scanning electron microscopy (SEM) was used to study the microscopic morphology of foams. The mechanical properties test results showed that the addition of SBR reduced the density of EVA/SBR/BR composite foams, and the addition of BR improved the mechanical properties and dimensional stability of the foams. By combining the advantages of both, the density of products is comparable to pure EVA, the tensile strength and the compressive strength are increased by 11% and 6.3% relative to pure EVA, respectively.

Study on combustion characteristics of glass fiber/phenolic resin composites

In order to study the combustion characteristics of glass fiber/phenolic resin composites, a conical calorimeter was used to explore the combustion characteristics of glass fiber/phenolic resin composites in an aircraft frame under different thermal radiation intensities, and the fire hazard of the materials was evaluated by evaluation index, and the limiting oxygen index at different temperatures was explored by combining the high temperature oxygen index meter. The test results show that when the ambient temperature increases from 20 °C to 220 °C, the limiting oxygen index first increases from 86.6 % to 93.7 %, and then decreases to 84.4 %. The oxygen consumption and CO2 release increase with the increase of thermal radiation intensity during combustion, and the release of CO decreases with the increase of thermal radiation. The heat release rate curve of the test material has only 1 enhancement peak. The heat radiation intensity increased from 50 kW/m2 to 70 kW/m2, and the peak heat release rate of the test material combustion increased from 64.7 kW/m2 to 100.7 kW/m2. The rate of mass loss of materials accelerates with the increase of thermal radiation intensity; As the intensity of thermal radiation increases, the fire hazard of the material increases.

Sodium Silicate/Urea/Melamine Ternary Synergistic Waterborne Acrylic Acid Flame-Retardant Coating and Its Flame-Retardant Mechanism.

Waterborne acrylic coatings, the largest market share of predominant environmentally friendly coatings, face limitations in their extensive application due to their flammability. The flame-retardant properties of the coatings could be significantly enhanced by incorporate inorganic flame retardants. However, inorganic flame retardants tend to aggregate and unevenly disperse in waterborne acrylic coatings, causing a substantial decrease in flame retardancy. In this work, sodium silicate was utilized as a flame retardant, with urea and melamine serving as modifiers and synergistic agents. This combination resulted in the preparation of a sodium silicate/urea/melamine ternary synergistic waterborne acrylic flame-retardant coating. This coating was applied to the surface of poplar veneer to create flame-retardant poplar veneer. Subsequently, various instruments, including a scanning electron microscope (SEM), a limiting oxygen index meter (LOI), a thermogravimetric analyzer (TG), and a cone calorimeter (CONE), were employed to investigate the relevant properties and mechanisms of both the flame-retardant coating and poplar veneer. The results demonstrated that the sodium silicate/urea/melamine ternary synergistic flame retardant did not exhibit aggregation and could be uniformly dispersed in waterborne acrylic coatings. The physical and mechanical properties of the ternary synergistic flame-retardant poplar veneer coating were satisfactory. Melamine and urea, acting as modifiers, not only greatly enhanced the dispersibility of sodium silicate in waterborne acrylic coatings, but also assisted in the formation of a silicon-containing char layer through the generation of nitrogen, achieving ternary synergistic flame retardancy. In conclusion, this work explores a novel method to efficiently and uniformly disperse inorganic flame retardants in organic coatings. It significantly improves the dispersibility and uniformity of inorganic flame retardants in organic polymers, thereby substantially enhancing the flame-retardant performance of coatings. This work provides a theoretical basis for the research and application of new flame-retardant coatings in the field of chemistry and materials.

Stress Control in Older People through Healing Garden Activities.

This study, conducted on a group older than 60-years-of-age, sought to verify if healing garden activities control stress in older people. The experimental group performed garden activities once a week for 12 weeks, for 2 h each day, and the control group continued their daily lives. Each group's cumulative stress at the beginning and end, along with total power (TP), the standard deviation of the normal-to-normal interval (SDNN), and the root mean square differences of successive R-R intervals (RMSSD), were measured using u-Bio MACPA, a stress index meter. The analysis showed that the experimental group had a statistically significant decrease in cumulative stress, compared to the control group; and also that TP significantly increased, compared to the control group. The SDNN and RMSSD of the experimental group increased, and decreased in the control group, but the changes were not statistically significant. The fact that cumulative stress decreased and stress evaluation indicators increased shows that daily stress can be controlled through healing garden activities. However, due to the small number of participants in the experiment, its ability to be generalized to all elderly people is subject to a number of limitations. Nevertheless, I think it is meaningful that the finding that garden activities are significant in mediating stress in the elderly was verified using a scientific measurement instrument. Future studies should explore the healing effectiveness of gardens in other age groups.

Drone-Based System to Reduce Air Pollution Using Inexpensive Materials

Outside, polluted air contains many particles that are harmful to all organisms. Currently, there are no reliable, efficient, or effective ways to clean outside air pollution. This paper describes an early attempt to create a drone-based pollution vacuum cleaner that uses inspiration from the tornado’s Fibonacci spiral shape’s ability to create powerful vacuums. By mounting various Fibonacci spirals onto a drone, the aim was to create a vacuum that can collect, and filter simulated polluted air. The reduction in pollution particles was measured with an Air Quality Index (AQI) meter. The engineering process involved: 3D printing and designing Fibonacci-shaped spirals with varying degrees of curvature. Testing various motors and spirals and their efficacy in vacuuming air into the filters. Testing the vacuum effect on the drone’s ability to fly The process compared the effectiveness of the spirals based on their improvement of the AQI in the simulated polluted environment. The wide spiral (Spiral #1) is 1.5cm in width, and 1cm in height with 5729.57 degrees of curvature resulting in the most reduced AQI, from 500 to a healthy breathable number in 15 minutes. In addition, the drone ascended 3 meters while withstanding the vacuuming effect coming from the attached spiral. The project utilizes natural designs such as the Fibonacci spiral shape of a tornado on a smaller scale as a prototype for an improved air filter. For further research, the plan is to make the drones autonomous and test more spirals using different materials.

The Burdens of Occupational Heat Exposure-related Symptoms and Contributing Factors Among Workers in Sugarcane Factories in Ethiopia: Heat Stress Wet Bulb Globe Temperature Meter

BackgroundHeat stress is a harmful physical hazard in many occupational settings. However, consequences of occupational heat exposure among workers in a sugarcane factory in Ethiopia are not well characterized. This study aimed to assess the level of occupational heat exposure-related symptoms and contributing factors. MethodsIn this cross-sectional study, five workstations were selected for temperature measurement. Heat stress levels were measured using a wet-bulb globe temperature index meter. A stratified random sampling technique was used to select 1,524 participants. Heat-related symptoms were assessed using validated questionnaires. ResultsThe level of occupational heat exposure was 72.4% (95% CI: 70.2%–74.8%), while 71.6% (95% CI: 69.3%–74.9%) of participants experienced at least one symptom related to heat stress. The most common heat-related symptoms were swelling of hands and feet (78%), severe thirst (77.8%) and dry mouth (77.4%). The identified risk factors were a lack of reflective shields (AOR: 2.20, 95% CI: 1.53, 3.17), not-enclosed extreme heat sources (AOR: 1.76, 95% CI: 1.23, 2.51), a lack of access to shade (AOR: 9.62, 95% CI: 6.20, 14.92), and inappropriate protective clothing provision (AOR: 1.58, 95% CI: 1.27, 2.71). ConclusionsThe burden of occupational heat exposure and heat-induced symptoms was high. Lack of reflective shields, the absence of enclosed extreme heat sources, a lack of access to shade, and inappropriate protective clothing provision were considerable attributes of heat stress. Therefore, the use of mechanical solutions to stop heat emissions at their sources and the key factors identified were areas for future intervention.

Effect of a layered combination of APP and TBC on the mechanics and flame retardancy of poplar strandboards

How to balance the flame-retarding and physico-mechanical properties of wood composites treated with chemicals remains a big challenge. Herein, a layered pattern of bi-component flame-retarding agent in strandboards was established by applying tris (2,3-dibromo-propyl) isocyanate (TBC) in the core and ammonium polyphosphate (APP) in the surface layers. The mechanical and flame retardant properties of treated strandboards were controlled by adjusting the addition ratio of APP to TBC. X-Ray computed tomography was applied to disclose the on-site distribution of APP and TBC chemicals in the strandboard matrices. Both oxygen index meter and cone calorimeter were used to characterize the burning behavior of the strandboards. Addition of TBC resulted in a higher-density core of strandboards. Compared to the untreated and evenly-distributed strandboards, internal bond (IB) strength and modulus of elasticity (MOE) were enhanced by up to 6% and 62.9%, respectively. Meanwhile, the peak heat release rate (pk-HRR) of strandboards after APP/TBC/APP treatment decreased by 33.6%, and the limited oxygen index (LOI) reached a maximum value of 38.2%. When exposed to combustion, the core layer of strandboard treated with TBC generates non-combustible gas and expands the surface char barrier established by APP, thereby enhancing flame retardancy. Compared to traditional methods, a lamination pattern of flame retardants in strandboards exhibits improved bonding performznd satisfied fire resistance. This innovative approach holds great potential for application in the fire safety wood composites industry.

Difference of Systolic Blood Pressure Between Arms and Its Influencing Factors Among People Over 35 Years Old in China

Abstract Background To investigate the detection of the increase of interarm systolic pressure difference (IASBPD) in people aged ≥35 years in our country and its related factors. Methods Stratified multistage sampling method was used to randomly select 262 urban and rural residents from 31 provinces from 2012 to 2015. Further, simple random sampling method was used to select 16 cities and 17 rural residents from eastern, central, and western regions. A total of 34,121 subjects aged ≥35 years were analyzed after removing the missing information. Data were collected by questionnaire, and blood pressure in both arms was measured by ankle–brachial index meter. All data were analyzed by SPSS 23.0 software. Continuous data were expressed as mean ± SD. Comparison between groups was performed using t-test if it was normal distribution, and rank-sum test if it was not. Categorical data were expressed as frequency sum rate or constituent ratio, χ2 test was used for comparison of various rates and constituent ratio, and rank-sum test was used for rank data. Multivariate logistic regression was used to analyze the influencing factors of IASBPD increase. Results The detection rates of IASBPD ≥10 and ≥15 mm Hg were 16.31% and 7.55%, respectively. The detection rate of IASBPD ≥10 mm Hg in males was higher than that in females (P < 0.05). Multivariate logistic regression showed that age, family history of hypertension, low HDL-C, hypertension, and abdominal obesity were risk factors for IASBPD ≥10 and 15 mm Hg (all P < 0.05). Conclusions The detection rates of IASBPD ≥10 and 15 mm Hg are 16.31% and 7.55%, respectively, in Chinese ≥35 years old people, and age, low HDL-C emia, family history of hypertension, hypertension, and abdominal obesity are the influencing factors of large differences in interarm blood pressure.

Performance and Microstructure Characterizations of Halloysite Nanotubes Composite Flame Retardant–Modified Asphalt

To solve the problems of low flame retardant efficiency and weak low-temperature performance of asphalt modified by conventional flame retardants (CFR), in this study, halloysite nanotubes (HNTs) and CFR were used to prepare nanocomposite flame retardants (NCFR) to modify asphalt. A fluorescence microscope (FM), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope/energy dispersive spectrometer (SEM/EDS) were used to characterize the microstructure of NCFR-modified asphalt. An oxygen index meter, Cleveland open cup, and cone calorimeter were used to test the flame retardant properties of the asphalt. A dynamic shear rheometer, bending beam rheometer, and force ductility tester were used to test the rheological properties of asphalt. At the same time, flame retardant–modified asphalt mixtures were prepared to verify the flame retardancy and road performance of the flame retardant–modified asphalt. The research results showed that the asphalt modified with 8% CFR and 1% HNTs (MA/CFR/1% HNTs) showed better dispersibility. The increase of limiting oxygen index and self-ignition temperature and the decrease of heat release rate and smoke production rate of MA/CFR/1% HNTs indicated that it has good flame retardancy. At 64°C, compared with modified asphalt (MA), the rutting factor of MA/CFR/1% HNTs increased by 88.17%, the creep recovery increased, and the irreversible creep decreased, indicating that its high-temperature performance improved significantly. At −18°C, compared with that of MA/CFR, the low-temperature creep stiffness of MA/CFR/1% HNTs decreased by 36 MPa and the creep rate of MA/CFR/1% HNTs increased by 0.034, indicating that only 1% HNTs can improve the effect of degraded CFR on the low-temperature performance of MA. Simultaneously, MA/CFR and MA/CFR/1% HNTs can improve the high-temperature performance and water stability of asphalt mixtures. Adding 1% HNTs to a MA/CFR-modified asphalt mixture can improve the low-temperature performance of the asphalt mixture to the level of the low-temperature performance of the modified asphalt mixture. In summary, the modification of asphalt with 1% HNTs and 8% CFR can effectively improve the flame retardant efficiency and significantly improve the road performance of asphalt.

Evaluation of Heat Stress Levels Inside Greenhouses during Summer in Korea.

Farmers working inside greenhouses during summer are at risk of heat-related illness. In this study, we compared the dry-bulb temperatures (DTs) and the wet-bulb globe temperature (WBGT) index inside and outside greenhouses. We then determined the criteria for appropriate working and resting times inside greenhouses. The measurements were performed during the hottest period in 2020 and 2021 for two greenhouses, representative of those commonly found in rural areas. A direct-reading WBGT index meter was used for these measurements, and Automated Synoptic Observing System (ASOS) data were used to obtain regional DT data. DTs inside the greenhouses were significantly higher than the ASOS DTs (p < 0.001). In addition, the August WBGT index inside was significantly higher than that outside the greenhouses (p < 0.001). We found that the temperature during the period between 08:00 and 19:00 exceeded the international threshold of 28 °C for heat-acclimatized workers performing moderate-intensity work, above which heat stress becomes a concern. Our results revealed that the thermal index inside can be significantly higher than that found outside greenhouses. Therefore, when work is required inside greenhouses during the summer, stricter standards and safety measures should be considered.

Job and demographic risk factors influencing cellular mediated hypersensitivity among Nigerian Laboratory University workers in multiple chemical exposures

Background: Chemicals from laboratories represent a significant risk in cellular mediated hypersensitivity (CMH) and chemo-induced skin injury due to chemical agents present under human skin layers absorbed from the surface. This study aimed to determine the occupational and socio-demographic characteristics of the laboratory workers associated with CMH in multiple chemical exposures. Design: This was a cross-sectional study on a population-based sample of Nigerian laboratory university workers. Methods: Data were collected using the erythema index meter. The study included 287 laboratory workers. Results: The results showed that the number of positive with CMH was 176 (61.3%) with 99 (56.3%) of them were male with AOR 0.31 (95%CI: 0.12, 0.77; p=0.011). Dark-skinned participants with CMH had adjusted odd ration, AOR 0.49 (95%CI: 0.21, 081; p =0.001). Most of the respondents have college education and have been exposed for 4-5hrs in the laboratory with AOR 2.42 (95%CI: 1.10, 5.38; p = 0.049) and 3.11 (95%CI: 1.77, 9.23; p =0.001) respectively. The use of personal protective equipment (PPE) was 60% less likely to be significantly induced with CMH with AOR 0.40 (95%CI: 0.22, 0.77; p =0.011). The Permissible exposure limit (PEL) of chemical was less but have an induced CMH with AOR 4.22 (95%CI: 2.88, 12.11; p =0.004). Conclusion: Results revealed that sex, skin color, working experience, educational level, PPE, PEL, and time of exposure were the probable predictive factors associated with the development of CMH. This study has shown that CMH was significantly associated with occupational and demographic factors. Better educational knowledge and attitude of hazards and safety in the laboratory would lead to a reduced rate of new cases.

Correlation between SPAD and chlorophylls a, b and total in leaves from Vaccinium corymbosum L. cv. Biloxi, Legacy and Victoria in the high tropics

Blueberries in the Ericaceae family are important, cultivable species for commercial and industrial purposes. Critical parameters for evaluating the nutritional and physiological status of plants include estimates of photosynthetic pigments such as chlorophylls; however, this is a destructive, expensive and time-consuming method that is not easily accessible for agricultural producers. For this reason, in recent years, several technological solutions have been made available, such as the SPAD-502 chlorophyll index meter, which has demonstrated efficiency in terms of rapid estimates of total chlorophyll content in the field. Therefore, the objective of this research was to evaluate the contents of chlorophylls a, b and total obtained with spectrophotometry and to determine the correlation with the non-destructive method (SPAD) in blueberry plant (Vaccinium corymbosum L.) cultivares Biloxi, Legacy and Victoria, in the vegetative phase under conditions of the municipality of Paipa-Boyaca (Colombia). The data obtained with the SPAD-502 ranged from 57.4 to 62.8 SPAD in the 'Victoria', 61.2 to 68.3 in the 'Biloxi', and 68.2 to 73.1 in the 'Legacy'. The content of chlorophylls a, b and total presented a positive and significant correlation with the SPAD index, with a correlation coefficient (r) greater than 0.91 and adjustment to simple linear regression models with a coefficient of determination (R2) greater than 0.90 in the three cultivars. This confirms the usefulness and importance of using SPAD for non-destructive estimation of chlorophyll content under field conditions.

Influence of siloxanes viscosity and concentration on low‐temperature impact modification and melt flow behavior of polycarbonate

AbstractReactive blending of polycarbonate (PC) with hydroxyl terminated polydimethylsiloxane (PDMSOH) enhances the impact strength at sub‐zero temperature and also influences the melt flow property of the modified PC. Both viscosity and concentration of the siloxane play role differently on modification of the properties. PDMSOH was incorporated in the polymer chains of PC by transesterification reaction in presence of alkali catalyst. Higher concentrations of siloxane though increased low‐temperature ductility but often at the expense of undue enhancement of melt flow property. Selection of PDMSOH of an appropriate viscosity however could overcome this problem. Different grades of siloxane modified PC could be developed having good impact strength at −30°C while simultaneously maintaining its desired melt flow property. Izod impact tester, melt flow index meter, viscometer, UV–Vis spectrometer and scanning electron microscope were used to characterize the material. This work will pave the way for developing desired grades of PC for low‐temperature applications.

Preparation of High-Efficiency Flame-Retardant and Superhydrophobic Cotton Fabric by a Multi-Step Dipping

Cotton fabric, as an important material, is suffering from some defects such as flammability, easy pollution and so on; therefore, it is important to make a flame-retardant and superhydrophobic modification on cotton fabric. In this study, we demonstrated a preparation of high-efficiency flame-retardant and superhydrophobic cotton fabric with double coated construction by a simple multi-step dipping. First, the fabric was immersed in branched poly(ethylenimine) (BPEI) and ammonium polyphosphate (APP) water dispersions successively, and then immersed in polydimethylsiloxane (PDMS)/cellulose nanocrystals (CNC)-SiO2 toluene dispersion to form a BPEI/APP/PDMS/CNC-SiO2 (BAPC) composite coating on the surface of the cotton fabric. Here, the hydrophobic modified CNC-SiO2 rods were used to construct the superhydrophobic layer and the BPEI/APP mixture was used as the flame-retardant layer, as well as SiO2 particles which could further improve the flame-retardant effect. PDMS was mainly used as an adhesive between the BPEI/APP layer and the CNC-SiO2 layer. The resulting cotton fabric shows outstanding flame-retardant properties, in that the value of oxygen index meter (LOI) reaches 69.8, as well as excellent superhydrophobicity, in that the water contact angle (WCA) is up to 156.6°. Meanwhile, there is a good abrasion resistance, the superhydrophobicity is not lost until the 16th abrasion cycles and the flame retardant retains well, even after 100 abrasion cycles in an automatic vertical flammability cabinet under a pressure of 8.8 kPa.

Multi-Objective Optimization and Performance Characterization of Asphalt Modified by Nanocomposite Flame-Retardant Based on Response Surface Methodology.

In order to improve the safety of the tunnel asphalt pavement in the event of a fire, and reduce the deterioration of the low temperature crack resistance of the asphalt by the flame retardant. The research uses aluminum hydroxide (ATH) as a smoke suppressant, diethyl aluminum hypophosphite (ADP) as a flame retardant, and halloysite nanotubes (HNTs) as a synergist to modified styrene-butadiene-styrene block copolymer (SBS) modified asphalt (MA). First, the content of ATH, ADP, and HNTs was used as the response variable. The physical properties (Penetration, Softening point, Ductility) and static flame retardant properties (Limiting oxygen index meter, Ignition point) of the asphalt modified by nanocomposite flame-retardant (HNTs-CFRMA) were the response variables. The response surface methodology was used to design the test, and regression models were established to analyze the influence of flame retardants on the performance of asphalt. Then, comprehensively considering the effects of physical properties and flame retardant properties, the normalized desirability function was used to perform a multi-objective optimization design on the components of the nanocomposite flame retardant modifier to obtain the best flame retardant formula. Finally, the rheological properties of MA, conventional flame-retardant modified asphalt (CFRMA), and HNTs-CFRMA were tested based on Dynamic shear rheometer, Multiple stress creep test, Force ductility tester, and Bending beam rheometer. The performance of flame-retardant and smoke suppression were tested by the Cone calorimeter tests. The result shows that ATH, ADP, and HNTs can enhance the high temperature performance of asphalt, reduce the penetration. The addition of HNTs can increase significantly the softening point and reduce the deteriorating effect of flame retardants on the low temperature performance of asphalt; the addition of ATH and HNTs can improve significantly the flame retardancy of asphalt. Based on the desirability function of power exponent, the formulation of the nanocomposite flame retardant with better physical properties and flame retardant properties is ATH:ADP:HNTs = 3:5:1, and the total content is 9 wt%. Nanocomposite flame retardants can improve obviously the high temperature rheological properties of asphalt. The rutting factor and the cracking factor of HNTs-CFRMA improve markedly, and the irrecoverable creep compliance is reduced, compared with MA and CFRMA. Nanocomposite flame retardant can make up for the deterioration of conventional flame retardants on asphalt’s low temperature performance. At the same time, it has better flame-retardant performance and smoke suppression performance.

Simultaneous ε-Keggin Al13 chloride salt and anionic polyacrylamide coagulation-flocculation system for agglomeration of trimetallic Cr-Ni-Fe doped core-shell microspheres of graphitized coke

Core-shell microspheres of graphitized carbon consisting of a solid carbonaceous core surrounded by a porous Cr-Ni-Fe shell are produced in ultra-high temperature ethane steam crackers. Considerable volumes of these microspheres are suspended in quench water and are directed to oceans while they have not been detected as pollutants so far. The importance of this work is studying and development of an environmental remediation process for extraction of coke microspheres from aqueous solution by ε-Keggin Al13 chloride salt as coagulant and anionic polyacrylamide (PAM) as flocculant in a stirred tank reactor equipped with silt density index meter and particle size analyzer. The effect of dissolved ions of Hofmeister series on zeta potential and electrical double layer compression was investigated. The role of charge density and chain length of PAM were also examined in favor of patch mechanism. The results revealed that the surface charge of suspended coke microspheres is controlled by the solid carbonaceous core while the porous metallic shell is ineffective. The aggregation of coke:Al13 flocs follows a multiple mechanism including point of zero charge, electrical double layer compression, charge neutralization, hydrophobic interaction, sweep floc, inter-particle polymer bridging and electrostatic patch flocculation. Surface adsorption of ε-Keggin Al13 chloride salt coagulants on the coke microspheres is limited to the critical level of 8 ppm because of the steric effect of ε-Keggin Al13 chloride salt clusters and the restricted bare surface of carbonaceous core matrix under the porous metallic shell. The sphericity parameter determined by surface to volume ratio of coke:Al13 flocs and it was used to quantify the degree of polymer bridging between the flocs.

Synergistic effect of fly ash on hydroxymethylated lignin‐containing flame retardant polypropylene: Flame retardancy and thermal stability

In this study, fly ash (FA) was used as a synergist to enhance the fire resistance of intumescent flame retardant polypropylene containing hydroxymethylated lignin. Effects of fly ash on flame retardancy and thermal stability properties of polypropylene (PP) composites were investigated using a limiting oxygen index (LOI) meter, UL‐94 vertical combustion tester, cone calorimeter, and thermogravimetric analyzer. The results showed that during combustion, incorporation of FA can effectively solve the dripping problem of the PP composites. Addition of 0.5% loading amount fly ash into the PP composite (0.5FA/IFR/PP) enhanced the flame retardancy significantly. Additionally, its LOI value increased from 28% to 33%, and UL‐94 vertical burning passed V‐0 grade from V‐2 rate. Notably, owing to addition of the fly ash, the peak of heat release rate of the pure PP decreased by 58.0%. Moreover, the release of CO2 and CO was largely suppressed, and higher char residue was obtained for 0.5FA/IFR/PP. Fire safety of the PP composites was significantly improved. From the analysis of charring residues, a possible flame retardant mechanism was proposed. That is, incorporation of fly ash increased the formation of a denser and intact char layer, which is important in inhibiting heat and flammable gases generated during combustion of underlined matrix.

Research on the Flame Retardancy Properties and Mechanism of Modified Asphalt with Halloysite Nanotubes and Conventional Flame Retardant.

The inflammability of asphalt road will promote fire spread in the tunnel and produce lots of toxic smoke. To improve the fire resistance of asphalt pavement, mineral powder flame retardants are generally replaced by flame retardants in equal amounts. In this study, the effects of the synergistic flame retardancy system of halloysite nanotubes (HNTs) and conventional flame retardants (CFR) on the flame retardancy performance and mechanism of asphalt were investigated. Firstly, the flame retardancy properties of the HNTs and CFR composite modified asphalt were investigated based on the Cleveland open cup method (COC), Limiting oxygen index meter (LOI), and Cone calorimeter tests (CCTs). Then, the flame retardancy mechanism of the modified asphalt was studied based on Thermogravimetric analyzer (TGA), Fourier-transform infrared (FTIR), and Scanning electron microscopy (SEM). The results show that adding HNTs could improve the flame retardancy of the CFR modified asphalt binder. When 1 wt % HNTs and 8 wt % CFR were used, the limiting oxygen index of asphalt increased by 40.1%, the ignition temperature increased by 40 °C, while the heat release rate, total heat release, the smoke production rate, total smoke release, and other parameters decreased with varying degrees. Based on TG, FTIR, and SEM, the targeted flame retardancy mechanism and synergistic effect of HNTs/CFR flame retardancy system were revealed and summarized as three stages: (1) Stage 1, aluminum hydroxide (ATH) absorbs heat through thermal decomposition and inhibits the decomposition of lightweight components in asphalt; (2) Stage 2, aluminum diethyl phosphate (ADP) decomposes and produces organic phosphoric acid, which catalyzes crosslinking and ring thickening of asphalt and the quenching effect of phosphorus free radicals to block the combustion; and (3) Stage 3, HNTs plays an important role in increasing the integrity and density of the barrier layer. In addition, the Al2O3 produced by the decomposition of ATH, the carbon layer formed by the ADP catalyzed pitch, and HNTs play a significant synergistic effect in the formation of the barrier layer. Thus, the combination of HNTs and CFR has been proved to be a prospective flame retardancy system for asphalt.

A Skin‐Inspired, Interactive, and Flexible Optoelectronic Device with Hydrated Melanin Nanoparticles in a Protein Hydrogel–Elastomer Hybrid

AbstractMelanin, a biologically occurring pigment featuring broadband optical absorption, ion‐binding affinity including antioxidative and radical‐scavenging properties, and hydration‐dependent electrical conductivity is an ideal natural semiconducting material for interfacing electronics with biological systems. Here, a skin‐mimicking optoelectronic device with a melanin nanoparticle (MNP) dispersion in a protein hydrogel–elastomer hybrid (a mimic of epidermis/dermis layers with melanin) and its application as a dopamine sensor and a UV index meter are reported. MNPs dispersed in water are placed in the elastomer reservoir with integrated silver nanowire electrodes and a transparent silk hydrogel window cover; they exhibit n‐type semiconducting behavior with increased conductivities compared with those of dehydrated MNPs. Enhanced generation of free radicals by light illumination results in an increase of the electrical conductivity. In addition, the artificial optoelectronic skin interacts with its environment through the silk hydrogel window. Applications of the device, including its use as a dopamine sensor and a UV index meter to detect dopamine and UV light passing through the window, are demonstrated. The sensitivity of the dopamine sensor is enhanced by the light illumination.

Simple in‐field evaluation of moisture content in curing forage using normalized differece vegetation index (NDVI)

AbstractProduction of hay at a proper moisture level is critical to reduce the spontaneous heating and nutrient loss during the preservation phase. Herein, we explored a new method for estimating the moisture content (MC) of field curing forages that uses a portable spectroradiometer (400–900 nm) and a hand‐held normalized difference vegetation index (NDVI) meter. The spatial distributions were assessed by a multispectral camera with unmanned aerial vehicle (UAV) platform. Field spectral measurements were conducted daily at 10 random plots over six trials at four forage fields across the entire curing period. Multispectral imagery acquisition by UAV flights was conducted at one trial. The MC (wet basis) was determined using a forced‐air oven. For 400–900 nm spectral reflectance measured by the spectroradiometer, we conducted linear regression analyses between the MC and all available combinations of a normalized difference spectral index (NDSI(Band1, Band2) = (ρBand1 − ρBand2)/(ρBand1 + ρBand2), where ρλ is the apparent reflectance and λ is the wavelength in nm). The combinations that are generally used as greenness indices showed high coefficients of determination, for example, red and near infrared (R2 = .76, RMSE = 10.66%) and green and red (R2 = .81, RMSE = 9.57%). The NDVI meter and multispectral imagery showed the feasibility of NDVI (R2 = .79, RMSE = 8.58% and R2 = .89, RMSE = 6.74%, respectively) as a parameter to estimate the MC. We were able to verify the spatial variability of the MC in the field based on the NDVI imagery, which indicates that our method provides information for site‐specific management (e.g., partial swath manipulation) and for decision‐making regarding the harvest time and location.