Wet Heat Research Articles

Alterations in the phytochemical composition and antioxidant activity of Ligustrum robustum according to continuous wet‐ and dry‐heat treatment

Small-leaved Kuding tea (SLKDT) obtained from Ligustrum robustum is a traditional tea substitute in southern China and has a range of physiological effects. However, the changes in its phytochemical composition after various heat treatments are not reported yet. Thus, the phytochemical composition and antioxidant activities of fresh leaves of SLKDT (LrF1) and SLKDT after high-temperature wet-heat treatment (LrF2) and wet- and dry-heat treatments (LrF3) were assessed using liquid chromatography-mass spectrometry, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities and lipid peroxidation inhibition activity of LrF1 and LrF3 were investigated. The results indicated that the phytochemical composition of LrF1, LrF2, and LrF3 was significantly different. Overall, 258 and 83 differential constituents, respectively, were obtained in LrF1 versus LrF2 and LrF2 versus LrF3. The differential constituents mainly included amino acids and their derivatives, nucleosides, flavonoids, terpenoids, simple phenylpropanoids, and coumarins. After heat treatment, SLKDT exhibited obvious changes in sensory characteristics and physiological properties, which may be related to the changes in the levels of amino acids, linalool, beta-geraniol, myricetin, naringin, fraxetin, and isoacteoside. Moreover, the antioxidant activities significantly changed after heat treatment of SLKDT. Overall, our study demonstrated that heat treatment can alter the phytochemical composition of SLKDT, thus affecting its sensory properties and physiological properties. PRACTICAL APPLICATION: This study preliminarily assessed the changes in the composition of small-leaved Kuding tea (SLKDT) after various heat treatments and revealed that the composition of SLKDT tea can be adjusted by various heat and temperature treatments.

Protein interactions during dry and wet heat pre-treatment of skim milk powder (dispersions) and their effect on the heat stability of recombined filled evaporated milk

Skim milk powder (SMP) as well as aqueous dispersions were subjected to dry and wet heat pre-treatment, respectively, to improve the heat stability of recombined filled evaporated milk (RFEM) derived therefrom. However, microrheological analysis revealed that prolonged incubation caused detrimental effects on the heat stability of RFEM, which were thought to be due to protein interactions. SDS-PAGE results indicated that protein aggregation via non-disulfide covalent bonds occurred upon long-time dry or wet heat incubation. This was probably related to some Maillard reaction products, which is sustained by the increase in lactulose and protein carbonyl content. Considerable protein aggregation via disulfide bonds in the serum was found upon wet heat incubation at temperatures of at least 80 °C. Principal component analysis (PCA) revealed that the negative effects of overprocessing on the heat stability of RFEM were predominantly related to protein cross-linking via non-disulfide covalent bonds related to protein carbonylation.

Effect of Different Pre‐Gelatinization Treatments on the Properties of Acidified Mung Bean Starch

AbstractMicrowave radiation processing technology is an emerging technology with good penetration, uniform heating, and rapidity characteristics. After microwave wet heat treatment, the viscosity of starch decreased, and the gelatinization temperature changed the granule morphology, crystalline properties, and chemical structure of starch, resulting in changes in the physical and chemical properties of starch. It can effectively improve the sensory quality of food and prolong the shelf life of starch products. It is widely used in food, pharmaceutical, agriculture, and other industries. The pre‐gelatinized starch showed irregular shape, rough surface, and apparent edges and corners. Moreover, the starch particles' crystal structure is destroyed, crystallinity decreased to 11.43%–14.91%, and no new groups are formed. The starch granules changed from an ordered structure to a disordered structure, and the order degree decreased to 0.998–1.025. The enthalpy decreased to 2.22–4.32 J/g, the gelatinization temperature increased to 88.53–94.43 °, and the viscosity decreased significantly. After pre‐gelatinization, the amylose content decreased to 13.84%–16.25%. At 90 °, the solubility and swelling degree decreased to 2.48%–7.33% and 16.80%–17.81%, respectively. The freeze‐thaw water precipitation rate increased to 41.92%–59.35%, the water‐holding capacity increased by 3 times and transparency increased to 93.60%–95.84%.

Study of Novel Oil-Immersed Torque Motor for Two-Dimensional Valve

The electro-mechanical converters of valves are mostly dry type, which cannot work for a long time under high currents due to heat dissipation. This paper presents a novel oil-immersed torque motor (OTM) that can carry out the 2D motion. The OTM has a separate wet working chamber and heat dissipation structure, and the coil is external to prevent oil contamination from causing short circuits. The equations of motion were established based on the equivalent magnetic circuit (EMC) method and its own characteristics, and the effect of oil damping in the working chamber on the dynamic characteristics of the novel OTM was studied. After analyzing its working principle and dynamic and static characteristics by finite element and numerical analysis software, a prototype was designed and machined, which could be operated in dry and immersed mode by adding parts. In addition, a dynamic and static test bench and a temperature rise test bench were established, and comparison experiments with a conventional dry-type torque motor (CDTM) were conducted. Experimental results showed that the prototype had a good thermal resolution in immersed mode, and when the coil was fully loaded (2.4 A), it still worked in the safe temperature range. The prototype had good current-torque characteristics and hysteresis linearity at a coil magnetomotive force (MMF) of 0–450 A. The output torque could reach 0.7 Nm when MMF exceeds 1000 A. The prototype had an approximately 4% faster step response in immersed mode and about 17.8% wider bandwidth than in dry mode, while the torque motor system was more stable due to the increased damping ratio. The measured open-loop dynamic and static characteristics met the requirements of the electro-mechanical converter of 2D servo valves.

Expression of the 2Duf protein in wild-type Bacillus subtilis spores stabilizes inner membrane proteins and increases spore resistance to wet heat and hydrogen peroxide.

This work aimed to characterize spore inner membrane (IM) properties and the mechanism of spore killing by wet heat and H2O2 with spores overexpressing the 2Duf protein, which is naturally encoded from a transposon found only in some Bacillus strains with much higher spore resistance than wild-type spores. Killing of Bacillus subtilis spores by wet heat or hydrogen peroxide (H2O2) was slower when 2Duf was present, and Ca-dipicolinic acid release was slower than killing. Viabilities on rich plates of wet heat- or H2O2 -treated spores +/- 2Duf were lower when NaCl was added, but higher with glucose. Addition of glucose but not Casamino acids addition increased treated spores' viability on minimal medium plates. Spores with 2Duf required higher heat activation for germination, and their germination was more wet-heat resistant than that of wild-type spores, processes that involve IM proteins. IM permeability and lipid mobility were lower in spores with 2Duf, although IM phospholipid composition was similar in spores +/- 2Duf. These results and previous work suggests that wet heat and H2O2 kill spores by damaging an IM enzyme or enzymes involved in oxidative phosphorylation.

Effects of glycation with chitooligosaccharide on digestion and fermentation processes of lactoferrin in vitro

This study aimed to investigate the digestion and fermentation processes of lactoferrin (LF) glycated with chitooligosaccharide (COS) under a controlled Maillard reaction, utilizing the in vitro digestion and fermentation model, and to compare the results of these processes to LF undertaken without glycation. After gastrointestinal digestion, the products of the LF-COS conjugate were found to have more fragments with lower molecular weight than LF, and the antioxidant capabilities (via ABTS and ORAC assay) of the LF-COS conjugate digesta also increased. In addition, the undigested fractions could be further fermented by the intestinal microbiota. Compared with LF, more short-chain fatty acids (SCFAs) were generated (from 2397.40 to 2623.10 μg/g), and more species of microbiota (from 451.78 to 568.10) were observed in LF-COS conjugate treatment. Furthermore, the relative abundance of Bacteroides and Faecalibacterium that could utilize carbohydrates and metabolic intermediates to produce SCFAs also increased in LF-COS conjugate than that of LF. Our results demonstrated that glycation with COS under the controlled wet-heat treatment Maillard reaction could modify the digestion of LF and have a potentially positive influence on the intestinal microbiota community.

Verification and development of a metamaterial with large bandwidth smooth transmission properties for the thermal properties sensing of Xuan paper

Metamaterial sensors are widely used because of their rich resonance behaviors. However, due to the dependence on resonance properties, many metamaterial sensors are difficult to be applied in measurement of the stationary thermal properties of Xuan paper samples in a wide frequency range. Many important properties of Xuan paper samples are related to thermal resonance properties,. such as folding resistance, tensile strength, ink-run property, whiteness, dry heat and wet heat aging. Here, a metamaterial sensor with smooth transmission performance in the operating frequency band is designed and fabricated. In experiments, by increasing temperature, the time for the thermal response current of the Xuan paper samples to reach the peak value is significantly reduced, and the average peak value is increased. The heat conduction of the Xuan paper samples is increased and the thermal resistance is reduaced. When the thickness of the Xuan paper sample is gradually increased, the time required for the thermal response current to reach the peak value is gradually increased and the average peak value is decreased. When the concentration of alum gelatin solution applied on the surface of the Xuan paper sample is gradually increased, the corresponding thermal response current is enhanced, and the time required to reach the peak is significantly reduced. The results show that the metamaterial sensor can be used to measure the thermal properties of Xuan paper samples.

Asphyxiation of Metarhizium robertsii during mycelial growth produces conidia with increased stress tolerance via increased expression of stress-related genes

Little is known about the impact of hypoxia and anoxia during mycelial growth on tolerance to different stress conditions of developing fungal conidia. Conidia of the insect-pathogenic fungus Metarhizium robertsii were produced on potato dextrose agar (PDA) medium under normoxia (control = normal oxygen concentrations), continuous hypoxia, and transient anoxia, as well as minimal medium under normoxia. The tolerance of the conidia produced under these different conditions was evaluated in relation to wet heat (heat stress), menadione (oxidative stress), potassium chloride (osmotic stress), UV radiation, and 4-nitroquinoline-1-oxide (=4-NQO genotoxic stress). Growth under hypoxic condition induced higher conidial tolerance of M. robertsii to menadione, KCl, and UV radiation. Transient anoxic condition induced higher conidial tolerance to KCl and UV radiation. Nutritional stress (i.e., minimal medium) induced higher conidial tolerance to heat, menadione, KCl, and UV radiation. However, neither of these treatments induced higher tolerance to 4-NQO. The gene hsp30 and hsp101 encoding a heat shock protein was upregulated under anoxic condition. In conclusion, growth under hypoxia and anoxia produced conidia with higher stress tolerances than conidia produced in normoxic condition. The nutritive stress generated by minimal medium, however, induced much higher stress tolerances. This condition also caused the highest level of gene expression in the hsp30 and hsp101 genes. Thus, the conidia produced under nutritive stress, hypoxia, and anoxia had greater adaptation to stress.

Germination physiology of Cochlospermum fraseri (Bixaceae), a deciduous tree from Northern Australia with physical seed dormancy.

Cochlospermum fraseri ('Kapok', Bixaceae) is a deciduous tree widely distributed throughout semi-arid and monsoon tropical northern Australia, and an important species for ecological restoration in the region. We aimed to better understand the seed biology and ecology of C. fraseri to determine the mechanisms by which seed dormancy might be alleviated, and the conditions that support germination to inform the use of this species in restoration. Dormancy breaking treatments (wet heat, dry heat, scarification) commonly applied to species with physical seed dormancy (PY) were tested along with stratification at 5-35°C (nine treatments). Following dormancy alleviation, seeds were germinated at nine temperatures (5 to 40°C) and five water potentials (0 to -0.8MPa) to understand environmental thresholds that regulate germination physiology in non-dormant seeds. A proportion of seeds (<0.3) lose dormancy naturally in response to warm (25 to 35°C) moist conditions, which dislodges the hypostase plug that prevents water uptake, whilst neither dry (≥100°C) nor wet (~100°C) heat were effective. Dormancy loss was also achieved by exposing seeds to concentrated (95-98% v/v) sulphuric acid for 3-7hours, after which high proportions (>0.75) of germination were observed. Cochlospermum fraseri seeds possess PY, which is alleviated by seasonal temperatures that occur when soil moisture is high, allowing seeds to employ a risk-adverse strategy and maximize establishment success in episodic environments with stochastic rainfall events. The understanding of dormancy alleviation requirements gained here adds to our knowledge of PY worldwide and recruitment dynamics in the Australian monsoonal tropics and will aid land managers and restoration practitioners by informing both seeding sites and optimal time for in situ sowing as well as the potential capacity of this species to form a persistent soil seed bank.

Impact of physical factors on bio-control potential of Lawsonia inermis leaf extract and bio-formulations as fungicides

The present study is carried out to ascertain the effect of different physical factors (sunlight, temperature, pH) and storage conditions on the antimicrobial efficacy of Lawsonia inermis leaf extracts and bio-formulation against the Alternaria alternata. In addition, the phytotoxic potential of 100% alcoholic crude extract as well as the acetone fraction of young leaves of Lawsonia inermis was also checked on seed germination of chilli (Capsicum annuum). Results showed that there was no adverse effect of wet heat (50–100 °C) and dry heat (40–90 °C) on extract and bio-formulation efficacy. Storage for 6 and 12 months had no adverse effect on extract and bio-formulation efficacy and the antifungal activity was observed similar to freshly prepared extract. We have used concentrations of 5,10, 15, 20 and 25 mg/ml to perform a phytotoxicity assay. The measurement of phytotoxicity was done by using the Standard blotter method and the result revealed that 5, 10 and 15 mg/ml concentration of the extract was non phytotoxic and were further used for in vivo experiments. These plant extracts and bio-formulations have extensive antimicrobial potential to be explored for application in sustainable agriculture.

Mathematical Modeling of Heat and Mass Transfer during Moisture–Heat Treatment of Castor Beans to Improve the Quality of Vegetable Oil

An important process in the technology of plant oil production by mechanical pressing is the wet–heat treatment of crushed oilseeds, in which the oilseed (compressed seed) is exposed to saturated vapor and a conductive heat supply. Optimal mode selection of wet–heat treatment based on a detailed study of the physical processes taking place in the compressed seed increases oil release, improves its quality indicators, and decreases energy consumption. Mathematical modeling is an advanced method for studying the dynamics of humidification and frying in the compressed seed. The article introduces a mathematical model and a numerical method for calculating heat-and-mass transformation and phase conversion in the process of the humidification and frying of compressed seeds of the castor plant in a continuous multi-stage heating kettle. This study provides equations for calculating the intensity of phase transformation on the inner and outer surfaces of the wet layer. Data verification indicates the adequacy of the mathematical model, effectiveness of the numerical method, and possibility of their use in optimizing the modes of wet–heat treatment for compressed seed raw material.

Aerosol Jet Printing of 3D Pillar Arrays from Photopolymer Ink.

An aerosol jet printing (AJP) printing head built on top of precise motion systems can provide positioning deviation down to 3 μm, printing areas as large as 20 cm × 20 cm × 30 cm, and five-axis freedom of movement. Typical uses of AJP are 2D printing on complex or flexible substrates, primarily for applications in printed electronics. Nearly all commercially available AJP inks for 2D printing are designed and optimized to reach desired electronic properties. In this work, we explore AJP for the 3D printing of free-standing pillar arrays. We utilize aryl epoxy photopolymer as ink coupled with a cross-linking “on the fly” technique. Pillar structures 550 μm in height and with a diameter of 50 μm were 3D printed. Pillar structures were characterized via scanning electron microscopy, where the morphology, number of printed layers and side effects of the AJP technique were investigated. Satellite droplets and over-spray seem to be unavoidable for structures smaller than 70 μm. Nevertheless, reactive ion etching (RIE) as a post-processing step can mitigate AJP side effects. AJP-RIE together with photopolymer-based ink can be promising for the 3D printing of microstructures, offering fast and maskless manufacturing without wet chemistry development and heat treatment post-processing.

Effects of different thermal processing methods on bioactive components, phenolic compounds, and antioxidant activities of Qingke (highland hull-less barley)

Qingke (highland hull-less barley) is a grain replete with substantial nutrients and bioactive ingredients. In this study, we evaluated the effects of boiling (BO), steaming (ST), microwave baking (MB), far-infrared baking (FB), steam explosion (SE), and deep frying (DF) on bioactive components, phenolic compounds, and antioxidant activities of Qingke compared with the effects of traditional roast (TR). Results showed that the soluble dietary fiber, beta-glucan and water-extractable pentosans of Qingke in dry heat processes of TR, SE, MB and FB had a higher content compared with other thermal methods and had a better antioxidant activity of hydroxyl radical scavenging and a better reduction capacity, while those in wet heat processes of BO and ST had a better antioxidant activity of ABTS radical scavenging and a better Fe2+ chelating ability. DF- and SE-Qingke had a higher content of tocopherol, phenolic, and flavonoid. Overall, 6 free phenolic compounds and 12 bound phenolic compounds of Qingke were identified, and free phenolic compounds suffered more damage during thermal processing. Principal component analysis showed that SE had more advantages in retaining and improving the main biological active ingredients of Qingke, and it may be the best method for treating Qingke.

The impact of humidity on Australia’s operational heatwave services

More frequent and intense heatwaves in the last decade have challenged humanitarian, health and meteorological authorities to mitigate impact. Meteorological heatwave monitoring and prediction services vary between heatwave definitions which either include humidity or are based only on temperature. Incorporation of humidity into human health heatwave studies and warning services has been variable. Whilst higher humidity is a known stressor during heatwaves, humidity is known to confound interpretation of heatwave data and can be difficult to monitor and forecast.This study examines the effect of humidity on diagnosed heatwave severity across Australia’s diverse climate zones. Dry bulb temperature is used as the only input into the Bureau of Meteorology’s current operational Excess Heat Factor (EHF) index. Alternative humidity-affected temperature indices (Apparent Temperature, Wet Bulb Globe Temperature and Heat Index) are examined for suitability as input to EHF to compare the incidence of dry and humidity-affected heatwave severity within Australia. This paper uses maximum and minimum dry and humidity affected temperature indices extracted from Australia’s Bureau of Meteorology Atmospheric high-resolution Regional Reanalysis for Australia (BARRA).Our investigation demonstrates Australia’s operational temperature-only percentile-based heatwave severity service provides effective heatwave warning guidance for five of Australia’s six diverse climate zones. However, rare very dry or very humid heatwaves in the tropics require both dry bulb temperature-only and Heat Index versions of Excess Heat Factor (EHF) severity index to provide competent operational heatwave early warning guidance.

Differential Roles of Three α-Crystallin Domain-Containing sHsps of Beauveria bassiana in Asexual Development, Multiple Stress Tolerance and Virulence.

Small heat shock proteins (sHsps) containing conserved α-crystallin domain play important roles in many cellular processes, but little is known about the functions of sHsps in filamentous entomopathogens. Here, three sHsps of Hsp20, Hsp30a, and Hsp30b were characterized in Beauveria bassiana, a filamentous fungal insect pathogen that serves as the main source of wide-spectrum fungal insecticides. The results demonstrated that these three genes are interrelated at the transcriptional level under normal and heat-shocked conditions. Meanwhile, all the deletion mutants showed significant but differential changes in cell wall integrity, antioxidant activity, hyphal tolerance to carbendazim fungicide, conidial tolerance to 45 °C wet heat and virulence. However, only Δhsp30b showed growth defects on rich and minimal media at 25 °C and Δhsp30a displayed the reduction in conidiophores and conidia. Moreover, the single deletion of hsp30a and hsp30b caused the decreases in hyphal growth at 34 °C and conidial tolerance to UV-B irradiation. Our findings provide a global insight into vital roles of hsp20, hsp30a, and hsp30b in asexual development, environmental adaptation, and fungal virulence of B. bassiana.

Methods of breaking physical dormancy in seeds of the invasive weed Mimosa pudica (Fabaceae) and a comparison with 36 other species in the genus.

The herbaceous perennial legume Mimosa pudica is an invasive weed in many tropical and subtropical regions and a serious problem for farmers since it is difficult to eliminate from crop field by hand. Moreover, it has water impermeable seeds, i.e., physical dormancy (PY), which could persist in the soil seed bank for a long period of time, thus making it a big challenge to control. The aims of this study were to test the effect of various laboratory methods on breaking PY in seeds of M. pudica, to identify the site(s) of water entry into seeds of M. pudica and compare results of dormancy-breaking methods for seeds of M. pudica with those of 36 other species of Mimosa reported in the literature. Mechanical scarification, wet heat and cycles of wet heat and ice water effectively broke PY in seeds of M. pudica. Following wet heat at 80 °C for 10 min, water uptake was via the hilar region but not the pleurogram; small cracks made in the pleurogram by this treatment were not deep enough for water to enter the seed. Neither tolerance to summer temperatures nor PY is likely to be the cause of invasiveness of this species, since seeds of rare and endemic species of Mimosa also tolerate summer temperatures and have PY.

Characteristics and circulation patterns for wet and dry compound day-night heat waves in mid-eastern China

Compound day-night heat waves (CohotEs) have more adverse effects on human health and ecosystem, and the consequences vary with humidity. This study classifies the CohotEs over Chinese mainland into wet and dry CohotEs, and compares their characteristics and associated circulation anomalies. Here, a populated region of mid-eastern China (MEC) with higher occurrence of both types of CohotEs is mainly focused. Results show that, during past six decades, wet CohotEs have higher frequency, longer duration and broader spatial scale, while dry CohotEs are less, shorter and more regional. Both types of CohotEs are associated with anticyclonic anomalies accompanied by the strengthening and northwestern expansion of western Pacific subtropical high (WPSH), leading to adiabatic heating with anomalous subsidence. The anomalies in wet CohotEs are influenced by the eastward expansion of East Asian westerly jet stream and northeastward expansion of the south Asia high. Anomalous southwesterlies transport additional water vapor from the tropics, leading to above-normal humidity that could reduce the amplitudes of anomalous subsidence but favor heat maintenance. By contrast, dry CohotEs are related to a more stable barotropic anticyclonic structure, and the anomalous signals are stronger in the middle-lower troposphere. Meanwhile, tropical cyclones appear over the South China Sea below 500 hPa, promoting the intensification of northwestward shifts of WPSH and anomalous northeasterlies over South China. So, lower humidity results from weakened northward water vapor transport could lead to faster heat dissipation and thus shorter duration for dry CohotEs. Our results emphasize the diversity of CohotEs, indicating that different types of CohotEs should be analyzed separately and multiple local and large-scale circulations need to be considered for better forecasts and predictions of CohotEs. • Characteristics of wet and dry compound hot extremes (CohotEs) are analyzed. • Circulation anomalies of wet and dry CohotEs are compared over mid-eastern China. • Anomalous anticyclone and western Pacific subtropical high (WPSH) cause CohotEs. • Wet CohotEs are influenced by eastward (westward) shifts of south Asia high (WPSH). • Dry CohotEs are related to shifts of WPSH and tropic cyclonic anomaly.

Effect of Different Physical Factors on efficacy of Thevetia Peruviana leaf extract and bio-formulations

Plant extract possess various secondary metabolites which are antifungal in nature and can be used as a safer alternative to the synthetic fungicides. As we all know that the chemical fungicides are harmful not only for humans but also for animals, other vegetation and for complete ecosystem. To overcome this problem, we have to focused on another alternative which are biologically libel and nonhazardous also. In the present study, herbal formulation was prepared in various combination ratios with Thevetia peruviana leaf extracts, cow dung and neem oil cake. The major aim of this short study is to check the stability of the said plant extracts and prepared herbal formulation on various physical factors like heat, temperature, pH, sunlight and storage etc. The extracts and herbal formulations were exposed to varying conditions of the parameters selected for a precise time period, and then observing the effect as a function of change in the crude extract activity, herbal formulation activity and change minimum inhibitory concentration of plant extract against the Alternaria solani. Control set of MIC, and extract free medium were maintained for comparison in each set of experiment against Alternaria solani. Results suggested that efficacy of leaf extracts and different formulations was not affected by wet heat up to 100 °C while slight reduction in antifungal activity of the plant extract and herbal formulations were observed with dry heat at 100 °C. In addition, slight reduction in activity of extract and herbal formulations was observed with change in pH. However antifungal activity of plant extract as well as herbal formulations, remain unaffected at alkaline pH (pH 9) and neutral pH (pH7). Storage for 6 and 12 months had no negative effect on extract and herbal formulation efficacy and the antifungal activity was observed similar to freshly prepared extract activity. The present study concluded that the plant disease or plant pathogens can be controlled by plant extract and plant based bioformulations by increasing the shelf life with some little changes in the physical parameters such as light, temperature, pH and storage.

Numerical study of heat and moisture transfer in thermal protective clothing against a coupled thermal hazardous environment

The objective of the study was to examine the effect of heat and moisture transfer on steam burn under a coupled thermal hazardous environment. A coupled model on the heat and moisture transfer between heat source, protective clothing and air gap was proposed. The developed model considers the non-transient equilibrium between three phases, the impinging jet flow between steam nozzle and fabric, the steam flow within the fabric induced by the pressure gradient, the dynamic moisture absorption, and the possible phase changes. The model was validated by a test apparatus of thermal protective performance. The results demonstrated that the developed model presented the potential for reasonably accurate prediction of the skin temperature and the steam burn in the coupled thermal environment. For the dry heat exposure, the radiant heat transfer absorbed by the skin was the main reason causing the skin burn. However, the existence of hot steam greatly reduced radiant and conductive heat transfer. The moisture phase change on the skin surface was the primary reason of the skin burn, indicating the occurrence of skin steam burn in the wet heat exposure. The research findings provided theoretical foundation and instruction for development of new thermal protective material and scientific selection of thermal protective equipment, which would be of great importance and necessity on safety improvement of fire-fighting operation.

Laser Ablated Janus Hydrogel Composite Membrane for Draining Excessive Blood and Biofluid around Wounds

AbstractIn order to avoid bacterial infection and mechanical damage to minor skin wounds, a bandage is usually put on the surface of the wound. The existing textile bandage can quickly absorb biofluids on the wound surface, but these absorbed biofluids remain in the interface between the wound and the bandage, which may not avoid the infection caused by these biofluids. Herein, a hydrophobic/hydrophilic Janus hydrogel composite membrane (JHCM) with a commercial band‐aid to achieve efficient cleaning of the biofluids on the wound surface is combined. By using the UV curing and femtosecond laser perforation method to fabricate the JHCM, the unidirectional biofluid transport performance of this JHCM is investigated. The JHCM can pump this biofluid to the hydrophilic layer through the hydrophilic inner wall of conical micropores and hydrogel layer driven. Also, this JHCM can weaken undesired wet adhesion and heat loss due to the removal of liquid while maintaining excellent antibacterial properties. Compared to the commercial band‐aid, there is significantly better in vivo wound healing effects for the JHCM@ band‐aid. This study is valuable for designing and fabricating next‐generation bandages with high performance for clinical applications.