High Relative Humidity Environment Research Articles

La/SnO2 nanoparticles: Hydrothermal synthesis, structure, and sensing performance in a high relative humidity environment

In this work, a simple one-step hydrothermal synthesis of La doped SnO2 nanocomposites was studied. The structure, morphology, specific surface area, and chemical composition were determined by XRD, SEM, BET, and XPS techniques. The gas sensing performance of SnO2 and La/SnO2 nanocomposites with varied La doping dosages on n-butanol gas was systematically investigated. The results manifested that under the testing environment (50 % relative humidity and 30 °C), La doped SnO2 nanocomposite sensor presented high response (69), excellent selectivity, good repeatability and long-time stability to n-butanol gas at 160 °C. Especially, the 7 mol% La doped SnO2 sensor displayed a 5.9 times higher response to 50 ppm n-butanol than the SnO2 sensor. In comparison with bare SnO2, La doping increased the band gap value of 7 mol% La/SnO2 nanocomposite by 6.23 %, decreased particle size by 11.83 %, and increased the oxygen defect concentration by 6.07 %. Due to the synergistic effect of the above factors, the gas sensing performance of La doped SnO2 nanocomposites towards n-butanol gas was enhanced. Therefore, La doped SnO2 nanocomposites might be a potential gas sensing material for monitoring n-butanol gas at relatively high humidity.

The impact of short-term exposure to meteorological factors on the risk of death from hypertension and its major complications: a time series analysis based on Hefei, China.

This study aimed to reveal the short-term impact of meteorological factors on the mortality risk in hypertensive patients, providing a scientific foundation for formulating pertinent prevention and control policies. In this research, meteorological factor data and daily death data of hypertensive patients in Hefei City from 2015 to 2018 were integrated. Time series analysis was performed using distributed lag nonlinear model (DLNM) and generalized additive model (GAM). Furthermore, we conducted stratified analysis based on gender and age. Relative risk (RR) combined with 95% confidence interval (95% CI) was used to represent the mortality risk of single day and cumulative day in hypertensive patients. Single-day lag results indicated that high daily mean temperature (T mean) (75th percentile, 24.9°C) and low diurnal temperature range (DTR) (25th percentile, 4.20°C) levels were identified as risk factors for death in hypertensive patients (maximum effective RR values were 1.144 and 1.122, respectively). Extremely high levels of relative humidity (RH) (95th percentile, 94.29%) reduced the risk of death (RR value was 0.893). The stratified results showed that the elderly and female populations are more susceptible to low DTR levels, whereas extremely high levels of RH have a more significant protective effect on both populations. Overall, we found that exposure to low DTR and high T mean environments increases the risk of death for hypertensive patients, while exposure to extremely high RH environments significantly reduces the risk of death for hypertensive patients. These findings contribute valuable insights for shaping targeted prevention and control strategies.

Trifolium repens L.-Like Periodic Micronano Structured Superhydrophobic Surface with Ultralow Ice Adhesion for Efficient Anti-Icing/Deicing.

Wind turbine blades are often covered with ice and snow, which inevitably reduces their power generation efficiency and lifetime. Recently, a superhydrophobic surface has attracted widespread attention due to its potential values in anti-icing/deicing. However, the superhydrophobic surface can easily transition from Cassie-Baxter to Wenzel at low temperature, limiting its wide applications. Herein, inspired by the excellent water resistance and cold tolerance of Trifolium repens L. endowed by its micronano structure and low surface energy, a fresh structure was prepared by combining femtosecond laser processing technology and a boiling water treatment method. The prepared icephobic surface aluminum alloy (ISAl) mainly consists of a periodic microcrater array, nonuniform microclusters, and irregular nanosheets. This three-scale structure greatly promotes the stability of the Cassie-Baxter state. The critical Laplace pressure of ISAl is up to 1437 Pa, and the apparent water contact angle (CA) is higher than 150° at 0 °C. Those two factors contribute to its excellent anti-icing and deicing performances. The results show that the static icing delay time reaches 2577 s, and the ice adhesion strength is only 1.60 kPa. Furthermore, the anti-icing and deicing abilities of the proposed ISAl were examined under the environment of low temperature and high relative humidity to demonstrate its effectiveness. The dynamic anti-icing time of ISAl in extreme environments is up to 5 h, and ice can quickly fall with a speed of 34 r/min when it is in a horizontal rotational motion. Finally, ISAl has excellent reusability and mechanical durability, with the ice adhesion strength still being less than 6 kPa and the CA greater than 150° after 15 cycles of icing-deicing tests. The proposed structure would offer a promising strategy for the efficient anti-icing and deicing of wind turbine blades.

Ce enhanced humidity-independent acetone-sensing properties of Co3O4 at a low operating temperature

As a p-type MOS, Co3O4 can detect acetone at low working temperatures. However, humidity significantly impacts the gas-sensing properties of MOS, particularly when the sensors are operated at a low temperature. Due to the incorporation of Ce, the operating temperatures of the Co3O4-based sensors were reduced from 160℃ to 100℃, while the humidity independences were enhanced. In a high relative humidity environment of 80 %, the gas response of the pure Co3O4 sample deteriorated significantly at 160℃. In contrast, the response of the 10 at% Ce-Co3O4 sample were remained, even at the lower operating temperature. In addition, the 10 at% Ce-Co3O4 sample showed a high and a selective response to 50 ppm acetone in the relative humidity environment of 80 %, and the detection limit for acetone reached 0.1 ppm. The influence of the interaction between the sensing material with water molecules on the humidity-independent gas-sensing property of Ce-Co3O4 was also explored.

Effect of compression ratios on the sorption behaviors of bamboo fiber-based composites

The sorption behaviors of bamboo fiber-based composites (BFC) play a critical role on its applications due to its impact on the dimensional stability and biological durability of the material. The sorption behaviors of Neosinocalamus affinis BFC with compression ratios of 1.50, 1.83 and 2.17 were studied in this project, aiming to optimize the manufacturing process of BFC to reduce the sorption of final products. It was found that the hygroscopicity of BFC samples with all three compression ratios is much lower than that of raw bamboo at all the studied relative humidity (RH) levels. The BFC manufactured with 1.50 compression ratios showed the lowest equilibrium moisture content (EMC). The sorption ability of BFC showed some increase with increasing compression ratio especially when the relative humidity (RH) was above 60%. An evolution in moisture absorption model of BFC was proposed based on the changes in its wettability, pore structures, and chemical compositions. Both introduction of phenolic formaldehyde (PF) resin and material densification reduced the water transfer pathway such as bamboo cell lumens, pits, and gaps, as well as the water absorption space in cell wall. Meanwhile, the BFC with higher compression ratio had increased difficulty to absorb water. The increase in sorption ability of BFC with higher compression ratio at high RH environment is proved to be the consequence of the higher content of its mesopore ratio resulting in increased poly-layer water content. Therefore, the RH of application occasions is critical to determine the optical compression ratio of BFC combining with other performance requirements.

Performance analysis of a temperature adaptive anti-condensation device in open-plan control cabinets

A temperature adaptive anti-condensation device was presented to adapt the anti-condensation requirements of shipborne open-plan control cabinets in non-operating state under high temperature, high relative humidity and harsh environment. By analyzing working principle of the anti-condensation device and influence factors of the ambient temperature, the dew point temperature was determined. According to the energy transfer theory, the heat transfer coefficient of heating units, the effective heat dissipation area of radiators, and the Cubic Feet per Minute (CFM) parameters of axial flow fans were deduced and calculated. Then dual-redundant temperature control strategy was adopted to control the internal temperature adaptively in the open-plan control cabinet between 33 °C and 40 °C. Furthermore, to quantify the numerical model, temperature distribution of the finite-element analysis (FEA) and experiments were carried out, of which the results were compared with the analytic solutions. The results indicated that surface temperatures of the internal electronic devices in the open-plan control cabinet can be controlled no less than the dew point temperature of 33 °C with no condensations. In summary, an optimum temperature, dry and reliable working environment for electronic devices was built to prevent corrosion and damage effectively, as well as the stable performance of the open-plan control cabinet was consequently enhanced.

Properties of poly (vinyl alcohol) films with embedded zeolitic imidazolate framework (ZIF-8) nanoparticles for food packaging applications.

This study evaluated the physical, mechanical, barrier properties, and transition temperatures of poly (vinyl alcohol) (PVA) films with embedded zeolitic imidazolate framework-8 (ZIF-8) nanoparticles carrying a natural antimicrobial, trans-cinnamaldehyde (TC). The ZIF-8 nanoparticles were synthesized using a sonochemical method and incorporated into polymeric matrices at mass ratio concentrations of 0% (control film) to 5% weight of ZIF-8@TC to PVA. Solutions were mixed, cast onto Petri dishes and dried for 12h at 37°C in a ventilated oven. The film samples were stored in airtight containers at room temperature and used within 1 week. The engineering properties of the PVA/ZIF-8@TC films were compared with those of low-density polyethylene (LDPE) film commonly used for packaging of spinach leaves. The glass transition, melting, and crystallization temperatures of PVA compositive films all increased (p<0.05) with ZIF-8@TC concentration. When exposed to high relative humidity environments, the PVA/ZIF-8@TC films had lower equilibrium moisture content (p<0.05) than the LDPE film. Although the composite films have different tensile properties from the LDPE film, embedding ZIF-8@TC into PVA films improved the tensile strength by 17%, making the PVA/ZIF-8@TC films suitable for low load-bearing applications such as food packaging. The gas barrier properties of PVA-based films differed only slightly with added ZIF-8@TC (p<0.05). PRACTICAL APPLICATION: PVA/ZIF-8@TC films are appropriate environment-friendly alternatives to polymeric food packaging in terms of their functional properties.

Factors determining the mechanical properties of banana fruit skin during induced ripening

Postharvest peel splitting in banana impairs visual quality and exacerbates mass loss, fruit fly infestation and microbial infection. The aim was to determine the mechanistic basis of peel splitting. We therefore monitored the change in physical and mechanical properties of the peel as affected by different storage conditions. Peel splitting occurred axially, in the fruit corners. It began 4 d after ripening induction. Splitting was preceded by radial cracks in the inner peel, that propagated towards the outside. In fruit stored at 98 % relative humidity (RH), splitting occurred in 38 % of fruit; there was no splitting in fruit stored at 14 or 60 % RH. The percentages of fruit with radial cracks in the inner peel were 63 %, 100 %, and 100 % at 14 %, 60 % and 98 % RH, respectively. The fracture force (Fmax) of the peel decreased rapidly from 53.0 ± 1.6 N to 2.1 ± 0.2 N during ripening. Simulated radial cracks (cuts) in the inner peel decreased Fmax from 22.8 ± 2.2 N to 15.9 ± 0.9 N Paring off the outer peel decreased Fmax from 18.9 ± 1.7 to 4.4 ± 0.8 N, but paring off the inner peel had no effect. Osmotic water uptake by peel discs incubated in glucose solutions decreased with increasing concentration. Water was lost to hypertonic glucose solutions causing discs to shrink. Epidermal and hypodermal cell wall thickness both increased due to cell wall swelling. Our results show: (1) the outer peel layers represent the mechanical backbone of the peel, (2) radial cracks in the inner peel are the first stage of peel splitting and (3) peel splitting is caused by local stress concentrations due to radial cracking and is exacerbated by cell wall swelling. Key to reducing peel splitting at retail is prompt removal of fruit from the high RH environment of the plastic-lined cartons.

Ozone-Facilitated Formation of Uranyl Peroxide in Humid Conditions.

Metaschoepite, [(UO2)8O2(OH)12](H2O)10, maintained in a high relative humidity (RH) environment with air initially transformed into an intermediate phase that subsequently was replaced by the peroxide phase studtite, [(UO2)(O2)(H2O)2](H2O)2, over the course of 42 days, as observed using Raman and infrared spectroscopy and powder X-ray diffraction. Addition of atmospheric ozone vastly increased the rate and extent of the transformation to studtite but only in a high-RH atmosphere. Owing to its strong affinity for peroxide, uranyl reacted with hydrogen peroxide as it formed and precipitated stable studtite. In this work, we provide a previously unidentified source of hydrogen peroxide and make a case for the re-examination of storage systems where the consequences of atmospheric ozone are not considered.

Experimental investigation on condensation characteristics of a novel radiant terminal based on sepiolite composite humidity-conditioning coating

The problem of condensation hinders the application and popularization of the radiant cooling system. According to the characteristics of temperature and humidity independent control of the radiant cooling system, a novel humidity-conditioning radiant terminal combined with solid humidity-conditioning material is proposed which can control temperature and humidity simultaneously, and a sepiolite composite humidity-conditioning coating (SCHCC) suitable for the radiant terminal with good humidity control ability in high relative humidity environment is prepared. The humidity-conditioning coating can adsorb water vapor in the air to reduce the risk of condensation that is different from the surface condensation of traditional radiant terminals. Then, the condensation and desorption characteristics of three humidity-conditioning boards are tested which is considered scaled-down humidity-conditioning radiant terminal. The results show that SCHCC has good humidity control ability in a high relative humidity environment, the moisture adsorption capacity of SCHCC between 85% RH and 95% RH is 0.208 g/g, which is 11.43 and 22.47 times that of gypsum and diatomite. The sepiolite based humidity-conditioning board (SHCB) with the best moisture adsorption characteristics has the longest condensation time, and the condensation time increases with the decrease of undercooling. SHCB also shows better humidity control ability even for the experimental condition without condensation within 300 min. In summary, SHCB can reduce the moisture content of indoor air through its excellent hygroscopic properties, and reduce the risk of condensation at the radiant terminal. • A novel humidity-conditioning radiant terminal is proposed. • The material has good humidity control ability under high relative humidity. • The condensation and desorption behavior of the novel radiant terminal is tested. • The novel radiant terminal can effectively prolong the surface condensation time.

Spider dragline silk-based humidity alarm sensor with ultra-high sensitivity

The sensitivity of Fabry–Perot (FP) sensor is determined by the change of cavity length. To achieve high sensitivity, we employ supercontraction property of spider dragline silk (SDS) to fabricate a FP cavity, and the length of the cavity can change up to 99.9% of the initial cavity length. The cavity consists of two reflecting surfaces which are the fiber end and the glass plane coated with gold. These two reflecting surfaces are connected by 1 cm long SDS, and the initial length of the FP cavity is 2 mm. Supercontraction property enables SDS shrink axially in length under high relative humidity (RH) environment, shrinking SDS pulls two reflecting surfaces closer to each other, so that the cavity length decreases and the free spectral range (FSR) of interference spectrum increases when environmental RH is more than 68%. Thus the proposed FP cavity length is adjustable with the change of RH, and it can change dramatically in the high humidity. FSR of the obtained spectrum can change from 0.600 nm to 466.538 nm when the RH increases from 68%RH to 95%RH. The experimental results indicate that the average sensitivity of the proposed SDS-based sensor is 27.355 nm/%RH in the range of 78%RH–95%RH, and the maximum sensitivity is 266.825 nm/%RH when RH increases from 94%RH to 95%RH. Supercontraction property makes SDS have the potential for RH sensing in high humidity range with high sensitivity. The proposed humidity sensor works only when the environmental RH increases to more than 68%RH, and its sensitivity increases with the increase of RH, thus it can work as a humidity alarm to protect storage from wetting.

Measurement of postmortem outflow facility using iPerfusion

The key risk factor for glaucoma is elevation of intraocular pressure (IOP) and alleviating it is the only effective therapeutic approach to inhibit further vision loss. IOP is regulated by the flow of aqueous humour across resistive tissues, and a reduction in outflow facility, is responsible for the IOP elevation in glaucoma. Measurement of outflow facility is therefore important when investigating the pathophysiology of glaucoma and testing candidate treatments for lowering IOP. Due to similar anatomy and response to pharmacological treatments, mouse eyes are a common model of human aqueous humour dynamics. The ex vivo preparation, in which an enucleated mouse eye is mounted in a temperature controlled bath and cannulated, has been well characterised and is widely used. The postmortem in situ model, in which the eyes are perfused within the cadaver, has received relatively little attention. In this study, we investigate the postmortem in situ model using the iPerfusion system, with a particular focus on i) the presence or absence of pressure-independent flow, ii) the effect of evaporation on measured flow rates and iii) the magnitude and pressure dependence of outflow facility and how these properties are affected by postmortem changes. Measurements immediately after cannulation and following multi-pressure facility measurement demonstrated negligible pressure-independent flow in postmortem eyes, in contrast to assumptions made in previous studies. Using a humidity chamber, we investigated whether the humidity of the surrounding air would influence measured flow rates. We found that at room levels of humidity, evaporation of saline droplets on the eye resulted in artefactual flow rates with a magnitude comparable to outflow, which were eliminated by a high relative humidity (>85%) environment. Average postmortem outflow facility was ∼4 nl/min/mmHg, similar to values observed ex vivo, irrespective of whether a postmortem delay was introduced prior to cannulation. The intra-animal variability of measured outflow facility values was also reduced relative to previous ex vivo data. The pressure-dependence of outflow facility was reduced in the postmortem relative to ex vivo model, and practically eliminated when eyes were cannulated >40 min after euthanisation. Overall, our results indicate that the moderately increased technical complexity associated with postmortem perfusion provides reduced variability and reduced pressure-dependence in outflow facility, when experimental conditions are properly controlled.

Influence of water content on the basic friction angle of porous limestones—experimental study using an automated tilting table

An accurate evaluation of the shear strength of discontinuities is frequently a key aspect for determining the safety of mining and civil engineering works and for solving instability issues at rock mass scale. This is usually done by using empirical shear strength criteria in which the basic friction angle (φb) is a relevant input parameter. Tilt testing is probably the most widespread method to obtain the φb due to its simplicity and low cost, but previous research has demonstrated that the results are strongly affected by several factors (e.g. surface finishing, cutting speed, specimen geometry, wear, time and rock type). In this connection, despite it is well known that water significantly reduces the mechanical properties of sedimentary rocks, very scarce research has focused on assessing the impact of the variations in water content on tilt test results. With the aim to fill this gap, saw-cut slabs of three limestone lithotypes were tilt tested in dry state, wet condition (fully water saturated, non-submerged samples) and under exposure to an environmental relative humidity (RH) of 90%. The results revealed that full water saturation caused moderate φb reductions in two lithotypes and a φb increase in one lithotype. This can be explained by their different microstructure and mineralogy, which makes that lubrication effect prevails over suction effect or vice versa. However, the exposure to a high RH environment did not cause significant φb variations. In addition, some important considerations related to tilt testing are provided and discussed, such as the intrinsic variability of the sliding angle (β) and the impact of multiple sliding on the same rock surfaces on β.

Hermetic bags maintain soybean seed quality under high relative humidity environments

Soybean seed quality is affected by high relative humidity (r.h.) during storage in the humid tropics resulting in loss of germination. This study assessed the effectiveness of hermetic bags in preserving soybean seed quality when stored at high r.h. over three months. Treatments consisted of Purdue Improved Crop Storage (PICS) and control polypropylene (PP) woven bags kept at 30 and 80% r.h. Moisture content and germination were measured each month. Moisture content did not change, except in seed stored in PP bag at 80% r.h. where it more than doubled after one month. There was no significant difference in germination rates between soybean seed stored in PICS bags at 30 and 80% r.h. over three months. Soybean seed stored in PP bag at 30% r.h. had germination rates similar to those observed in PICS bags at 30 and 80% r.h., except after the third month where it significantly decreased compared to PICS bags at 30%. Germination rates of soybean seed stored in PICS at 30% and 80%, and PP bags at 30% decreased by about 3, 6, and 7%, respectively. However, the germination rates of soybean seed stored in PP bags at 80% r.h. dropped by 98% after three months. There was a significant negative correlation of −80.6% (Pearson correlation) between moisture content and seed germination. Farmers and seed producers/traders in the humid tropics can safely preserve soybean seed using commercially available hermetic bags.

Optimizing the Packing Density and Chemistry of Cellulose Nanofilters for High-Efficiency Particulate Removal

The global spread of COVID-19 as well as the worsening air pollution throughout the world have brought tremendous attention to the development of materials that can efficiently capture particulate matter. We suggest that the high porosity of electrospun filters composed of nanofibers could provide minimal obstruction to air flow, while their high tortuosity and surface area-to-volume ratio present an excellent platform to capture particulates. In this study, the removal of nanoscale particles via in-house fabricated cellulose nanofilters is significantly enhanced by chemically functionalizing the fibers’ surface via the deposition of the bioinspired glue polydopamine (PDA) or the polycation poly(diallyldimethylammonium chloride) (PDADMAC). The effects of filter packing density, layering thickness, and chemistry on their performance, i.e., their filtration efficiency, most penetrating particle size (MPPS), particle fractional penetration percent, and performance in a high relative humidity environment, were investigated. When evaluated in an extremely hazardous environment (PM concentration ∼ 2000 μg m–3), the filtration efficiency, pressure drop, and quality factor for the cellulose nanofilters were measured to be >98.0%, <200 Pa, and ∼0.03 Pa–1, respectively. When we evaluated the performance of a composite hydrophobic/hydrophilic filter in an 80% relative humidity environment, a 99.8% filtration efficiency was achieved. We have demonstrated that the removal of nanoscale particulates can be effectively captured using cellulose-based nanofilters, even in a nonideal high humidity environment. These fundamental investigations into the structure–property-chemistry relationships of in-house electrospun nanofilters on nanoscale particulate removal hold the potential to help drive the future engineering of nanofilters for air purification applications, which is a timely and extremely important concern.

Experimental study on a wet precooling system for fruit and vegetables with ice slurry

Aiming at the application of fruit and vegetables precooling, an innovative wet precooling system with ice slurry as a cooling medium was proposed. A small wet precooling room performance test platform was built. With apples as the precooling subject, the temperature and relative humidity in precooling room, the cooling rate and weight loss of apples as indexes, by changing the weight concentration of ice slurry additives (0%-8%), the ice fraction (0%-10%) and the ice slurry flow rate (50-150 L h−1), the precooling experiments were carried out. The results showed that increasing the concentration of ice slurry additives (NaCl) could effectively reduce the equilibrium temperature in precooling room. For the ice slurry solution with the additive concentrations of 0%, 2%, 4%, 6% and 8%, the equilibrium temperature in precooling room were 4.3°C, 1.7°C, 0.4°C, 0.0°C and -0.7°C, respectively. When the ice fractions increased from 0% to 10%, the precooling time decreased from 165 min to 96 min, and the weight loss decreased from 2.11% to 0.42%. When the ice slurry flow rate increased, the relative humidity in precooling room increased, and the cooling rate of apples firstly increased rapidly and then leveled off. When the flow rate reached 100 L h−1, the relative humidity remained above 90%. The precooling system has a strong applicability, easy to realize the stable environment of low temperature and high relative humidity (0°C, >90%), so it has a large application space in the precooling and fresh-keeping of fruit and vegetables.

Effect of Negative Bias Voltage on Tribological Properties under High Relative Humidity Environment and Corrosion Resistance of Boron Carbide Coatings

Humid air is a very important service environment, in which metal friction parts should be enhanced to offer excellent corrosion resistance and wear resistance. The B4C coating is an excellent candidate material to enhance the corrosion resistance and tribological behaviors. The purpose is to investigate the effect of negative bias voltages on the tribological properties of B4C coatings under a high relative humidity environment. Amorphous B4C coatings were successfully prepared by closed field unbalanced magnetron sputtering technology and its microstructure, hardness, elastic modulus, adhesive force and tribological properties were systematically studied. Results demonstrate that the B4C coatings deposited at each negative bias voltage have a columnar structure and the surface roughness remained unchanged (about 1.0 nm), while the thickness, hardness, elastic modulus and adhesion force increase first and then decrease with the negative bias voltage increasing. Among them, the B4C (−50 V) coating showed the best mechanical properties. It should be noted that the B4C (−50 V) coating with an excellent corrosion resistance also exhibits the lowest friction coefficient (~0.15) and wear resistance (7.2 × 10−7 mm3·N−1·m−1) under humid air (85% RH). This is mainly due to the tribochemical reaction of B4C during a sliding process to produce boric acid at the sliding interface. B4C coatings can provide an excellent corrosion resistance and high wear resistance due to their high chemical stability and high hardness.

The influence of light and relative humidity on the formation of epsomite in cadmium yellow and French ultramarine modern oil paints

The effect of relative humidity (RH) and light on the development of epsomite (MgSO4·7H2O) in Winsor & Newton cadmium yellow (CY) and French ultramarine (FU) artists’ oil colour paints was investigated. Tube paint samples were aged for 12 weeks at either 50% or 75% RH, under ambient light (200 ± 1 lx), elevated light (11,807 ± 328 lx), and near-dark conditions. Aged paint samples were characterised using light microscopy (LM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Results indicated that ageing at 75% RH in elevated light conditions, promoted the formation of hydrated magnesium sulphate (MgSO4·6–7H2O) crystals on the surface of both paints. The formation of sodium sulphate (Na2SO4) as a degradation product of French ultramarine oil paints after ageing at 75% RH in elevated light conditions is described. The formation of magnesium sulphate crystals in the absence of elevated SO2 is a new finding. For both cadmium yellow and French ultramarine oil paints, the pigments present are a likely source of sulphur, enabling the formation of sulphate salts, i.e., cadmium sulphide (CdS) yellow, and the sulphur radical anions (S3−) present in ultramarine pigment. Sulphur-containing impurities arising from pigment manufacture are an additional possibility. It was previously theorised that epsomite formation in water-sensitive twentieth century oil paintings resulted from exposure to the elevated atmospheric sulphur dioxide (SO2) levels of the 1950s–1970s. This study demonstrates that hydromagnesite-containing cadmium yellow and French ultramarine oil paints of any period may be vulnerable to water-soluble sulphate salts formation and that this process is promoted by exposure to light and high (75%) RH environments. The formation of sulphate salts as a degradation product is known to contribute toward the development of water sensitivity of modern oil paintings which can pose significant challenges to conservation. Therefore this study highlights the importance of minimising exposure to light and raised relative humidity for paintings containing such CY and FU oil paint passages, to help slow down these types of degradation phenomena which have implications for preservation.

Effect of nitromethane on fuel/air explosion characteristics under different ambient conditions

The impact of nitromethane on the explosion characteristics of diethyl ether -aluminium powder mixed fuel in the presence of different ambient factors is studied in a 20 L sphere-shaped explosion vessel. The explosion pressure of the fuel is obtained by a series of experiments, and the mechanism of nitromethane during these experiments is deduced by analysing the maximum rate of pressure increase and the gas products. The results showed that a synergistic effect existed between nitromethane and diethyl ether at high mass concentrations. The self-decomposition reaction of nitromethane enables high mass concentration fuels to react more fully, maintaining a higher explosion pressure under a low-pressure or high-relative humidity environment.

Improvement mechanism of NO photocatalytic degradation performance of self-cleaning synergistic photocatalytic coating under high humidity

Photocatalytic coating has been widely studied as a promising material to remove air pollutants. However, the effectiveness and long-term effect of photocatalysis in high relative humidity environment is still the main challenge in this field. In this study, a fluorinated WO3-TiO2 nanorods/SiO2 epoxy photocatalytic superamphiphobic coating (FTSE coating) was prepared using a simple spraying method. The micromorphology and chemical composition of FTSE coating was characterized by SEM, EDS, FT-IR, XPS and TGA techniques. The advanced contact angle and hysteresis angle test show that the FTSE coating had excellent superamphiphobicity. The mechanical abrasions, corrosion resistance and UV aging tests show that the FTSE coating exhibited reasonable durability. Besides, the NO degradation efficiency of hydrophilic and superamphiphobic coatings with contact angles of 20.19°, 87.74°, 162.93° and 164.47° was tested in different humidity environment. The results showed that the superamphiphobic coating exhibited more superior photocatalytic degradation efficiency (84.02%) than the hydrophilic coating (51.38%) at a high relative humidity (RH=98%). Finally, FTSE coating exhibited prominent photocatalytic stability and the synergistic effect of photocatalysis and self-cleaning. After 30 d outdoor weathering test, the NO degradation efficiency decreased by 13.07% and recovered to the original level after flushing. The improvement mechanism of NO degradation performance was proposed based on the characteristics of superamphiphobic surface.