Low Humidity Research Articles

Survival of Salmonella enterica and Enterococcus faecium on Abiotic Surfaces During Storage at Low Relative Humidity

Currently, there is limited knowledge on the survival of bacteria on surfaces during postharvest handling of dry products such as onions. Extended survival of microorganisms, coupled with a lack of established and regular, validated cleaning or sanitation methods could enable cross-contamination of these products. The aim of the study was to evaluate the survival of a potential surrogate, Enterococcus faecium, and Salmonella enterica on typical onion handling surfaces, polyurethane (PU), and stainless steel (SS), under low relative humidity. The influence of onion extract on the survival of E. faecium and Salmonella on PU and SS was also investigated. Rifampin-resistant E. faecium NRRL B-2354 and a five-strain cocktail of Salmonella suspended in 0.1% peptone or onion extract were separately inoculated onto PU and SS coupons (2 × 2 cm), at high, moderate, or low (7, 5, or 3 log CFU/cm2) levels. The inoculated surfaces were stored at ∼34% relative humidity and 21°C for up to 84 days. Triplicate samples were enumerated at regular intervals in replicate trials. Samples were enriched when populations fell below the limit of detection by plating (0.48 log CFU/cm2). Scanning electron microscopy was used to observe the cell distribution on the coupons. Reductions of E. faecium of less than ∼2 log were observed on PU and SS over 12 weeks at all inoculum levels and with both inoculum carriers. In 0.1% peptone, Salmonella populations declined by 2 to 3 log over 12 weeks at the high and moderate inoculum levels; at the low inoculum level, Salmonella could not be recovered by enrichment at 84 days. Survival of E. faecium and Salmonella was significantly (P < 0.05) enhanced over 84 days of storage when suspended in onion extract, where cells were covered by a layer of onion extract. E. faecium might have utility as a conservative surrogate for Salmonella when evaluating microbial survival on dry food-contact surfaces.

Intravital Imaging of the Human Cornea Reveals the Differential Effects of Season on Innate and Adaptive Immune Cell Morphodynamics

Defining how the invivo immune status of peripheral tissues is shaped by the external environment has remained a technical challenge. We recently developed Functional invivo confocal microscopy (Fun-IVCM) for dynamic, longitudinal imaging of corneal immune cells in living humans. This study investigated the effect of seasonal-driven environmental factors on the morphodynamic features of human corneal immune cell subsets. Longitudinal, observational clinical study. Sixteen healthy participants (aged 18-40 years) attended 2 visits in distinct seasons in Melbourne, Australia (Visit 1, November-December 2021 [spring-summer]; Visit 2, April-June 2022 [autumn-winter]). Environmental data were collected over each period. Participants underwent ocular surface examinations and corneal Fun-IVCM (Heidelberg Engineering). Corneal scans were acquired at 5.5 ± 1.5-minute intervals for up to 5 time points. Time-lapse Fun-IVCM videos were created to analyze corneal immune cells, comprising epithelial T cells and dendritic cells (DCs), and stromal macrophages. Tear cytokines were analyzed using a multiplex bead-based immunoassay. Difference in the density, morphology, and dynamic parameters of corneal immune cell subsets over the study periods. Visit 1 was characterized by higher temperature, lower humidity, and higher air particulate and pollen levels compared with Visit 2. Clinical ocular surface parameters and the density of immune cell subsets were similar across visits. At Visit 1 , corneal epithelial DCs were larger, with a lower dendrite probing speed (0.38 ± 0.21 vs. 0.68 ± 0.33 μm/min; P < 0.001) relative to Visit 2; stromal macrophages were more circular and had less dynamic activity (Visit 1, 7.2 ± 1.9 vs. Visit 2, 10.3 ± 3.7 dancing index; P < 0.001). Corneal T cell morphodynamics were unchanged across periods. Basal tear levels of interleukin 2 and CXCL10 were relatively lower during spring-summer. This study identifies that the invivo morphodynamics of innate corneal immune cells (DCs, macrophages) are modified by environmental factors, but such effects are not evident for adaptive immune cells (T cells). The cornea is a potential invivo window to investigate season-dependent environmental influences on the human immune system. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Investigation of purge angle on the air inhomogeneity reduction and energy efficiency improvement of the desiccant wheel dehumidification system

ABSTRACT The rotary desiccant wheel dehumidification system has been extensively applied to achieve deep dehumidification in the modern environment with low humidity ratio. The effect of mixing destruction caused by the temperature and humidity inhomogeneity on the thermodynamic performance of the desiccant wheel deep dehumidification (DWDD) system has not been thoroughly illustrated. This research aims to reduce the mixing destruction and improve the overall energy efficiency of the DWDD system. Numerical analyses were carried out to investigate the mixing destruction characteristics of the deep dehumidification process. The results revealed that the mixing exergy destruction gradually becomes a prominent factor as regeneration temperature and humidity ratio increase under deep dehumidification, and there is a significant temperature and humidity ratio gradient in the transition angles from the regeneration side to the process side. The purge angle is regulated to reduce the average temperature and humidity ratio on the process side and lower the air inhomogeneity. The exergy efficiency of the desiccant wheel can be improved from 44.8% to 73.9% at the regeneration humidity ratio of 20 g/kg under the effective purge angle of 30°, indicating a considerable enhancement of exergy efficiency under the effective purge angle at a high regeneration humidity ratio.

Study on performance and water deactivation mechanism of low-temperature denitrification catalyst in high-humidity flue gas

To address water poisoning issues of Selective Catalytic Reduction (SCR) denitrification catalysts in high-humidity flue gas, this study synthesized catalysts including Co–Mn/TiO2, Co–Mn–Ce/TiO2, Co–Mn–Ce/TiO2–Si, and Co–Mn–Ce/TiO2 (stearic acid). The activity of the catalysts at low temperatures and high humidity (140–180 °C, 0–35 vol%) was evaluated. Furthermore, the characterization of the most effective of these (the Co–Mn–Ce/TiO2 (stearic acid) catalyst) was performed. The results revealed distinct mechanisms of water poisoning under high- and low-humidity conditions. Under high humidity, the dissolution of water molecules affected the catalyst structure and thereby, resulted in reduced dispersibility of the active components. Conversely, at low humidity, the dissolution effect was relatively marginal, which resulted in a more stable catalyst structure. High-humidity flue gas reduced the catalyst acidity and thereby, hindered NH3 adsorption. Meanwhile, low-humidity flue gas had a lesser impact on the catalyst. High-humidity flue gas hinders the conversion of Co ions in Co–Mn–Ce/TiO2（stearic acid ) to higher oxidation states and reduced Ce4+ to Ce3+. This resulted in decreased Mn4+ on the catalyst surface and reduced chemisorbed oxygen (Oa). This, in turn, affected the adsorption and storage of oxygen by the catalyst.

Gas Transport Resistance of Hydrocarbon-Based Catalyst Layers in Proton-Exchange Membrane Fuel Cells

Recent developments in hydrocarbon-based proton exchange membrane fuel cells have significantly narrowed the performance gap compared to state-of-the-art cells using perfluorosulfonic acid ionomers (PFSA). However, balancing protonic resistance and gas transport resistance in the catalyst layer remains a challenge at low humidity. This study investigates gas transport resistance and its components in sulfonated phenylated polyphenylene-based catalyst layers using various limiting current methods. Results show that increasing the dry ionomer to carbon (I/C) ratio from 0.2 to 0.4, a measure to catch up with protonic resistance of PFSA-based catalyst layers, significantly increases gas transport resistance in the cathode catalyst layer by 28 %. The data suggest a strong correlation between local gas transport resistance and IEC. A high IEC is beneficial for the gas transport through the ionomer film. However, at low ionomer volume fractions the local gas transport resistance is dominated by the I/C independent interfacial resistance. Furthermore, a low IEC hydrocarbon ionomer, such as Pemion® PP1-HNN4–00-X (IEC = 2.5 meq g−1), not only exhibits a beneficial interfacial resistance, but also suppresses excessive ionomer swelling, which typically occurs during operating conditions where liquid water is forming.

Hot air convection drying characteristics and microstructures of Pt/C catalyst layers in proton exchange membrane fuel cells

Large-scale fabrication of membrane electrode assemblies for proton exchange membrane fuel cells normally uses hot air convection drying of the catalyst layer (CL). The temperature, velocity, and relative humidity of the hot air affect the CL microstructure and, consequently, the power generation rate. This study experimentally investigated the impact of the hot air temperatures (30 °C, 50 °C, 70 °C and 90 °C), velocities (0.5, 1.0, 1.5 and 2 m/s) and relative humidities (5%, 10%, 20% and 30%) on the CL drying characteristics and microstructures. The mass loss was recorded by an electronic balance as the slurry coating dried with the CL microstructure then evaluated using a scanning electron microscope and nitrogen absorption-desorption measurements. The drying was almost completed for all cases within 90 s. A correlation was then developed for the CL hot air convection drying moisture ratio which was best fit by the two-term exponential model. The correlation accurately predicted the data for low relative humidities with average differences within 10%. The hot air temperature, velocity and relative humidity can significantly affect the CL pore size. High temperatures and velocities formed thicker CLs, while high relative humidities led to thinner CLs. These results indicate that the CL microstructure can be regulated by controlling the drying conditions.

A Cold Habitat: Mapping Blade Assemblages Between the Siberian Altai and the Tibetan Plateau During MIS 3

How and why early hunter–gatherers expanded into the challenging environments of the Tibetan Plateau during the Pleistocene remain largely unexplained. The discovery of the archaeological site of Nwya Devu, characterized by lithic blade production, brings new evidence of human expansion to high elevations ca. 40–30 ka. The blade assemblage currently lacks technological antecedents in East Asia. During Marine Isotope Stage 3, the surrounding lowlands to the Plateau were dominated by a distinct type of industry broadly named “core and flake.” It is suggested that the Nwya Devu blade assemblage derives from traditions in the eastern Eurasian Steppe, a clustered hub for Upper Paleolithic blade technology. In contrast to the East Asian lowlands, the Tibetan Plateau shares a number of environmental similarities with North and Central Asia such as low temperature and humidity, long winters, strong seasonality, and grassland landscapes. Blade and core-and-flake technologies tend to be associated with different environments in eastern Asia. We hypothesize that this geographic distribution indicates different sets of behavioral adaptations that map onto distinct ecozones and are relevant to human expansion to the Tibetan Plateau during Marine Isotope Stage 3. To evaluate the working model, we characterized the environmental parameters for both blade and core-and-flake technologies in eastern Asia during the period. The results show that environmental conditions on the Plateau and at the Nwya Devu site align with those of blade assemblages documented in the Eurasian Steppe and contrast with those of core-and-flake assemblages. Blade technology is strongly associated with low-temperature environments. These findings suggest that hunter–gatherers from the steppe belt may have benefited from their behaviorally adaptive advantages when moving into the highland environments of the Tibetan Plateau, 40–30 ka.

Differences in The Effects of Coconut Oil and Aloe Vera in Accelerating The Healing of Diaper Rashes in Babies

Baby's skin tends to become easily irritated due to low humidity. Irritation can occur in babies due to environmental temperatures that are too cold so that the baby's skin easily dries out and becomes itchy. Diaper rash is an inflammatory condition of the skin on the baby's thighs and buttocks due to friction between the skin and diapers which generally contain the baby's feces and urine for a long time. Diaper rash has signs of swelling and reddish skin on the thighs and buttocks. To treat diaper rash, non-pharmacological therapy is needed, such as administering coconut oil or aloe vera, which are known to contain many properties such as proteins, carbohydrates, vitamins and secondary metabolites which can act as antibacterials and antiseptics. The type of research chosen was quantitative with a pre-experimental design using the two group pretest-posttest method. The samples were babies aged at least 3 months and a maximum of 1 year who were known to have diaper rash which was determined using the purposive sampling method. The sample of babies consisted of 18 people, which would be divided into 9 people for the two types of interventions carried out. The instruments used are an observation sheet for the degree of diaper rash and SOP, where the results will be analyzed using univariate and bivariate. The results of the study showed that the administration of coconut oil and aloe vera could influence the diaper rash category, where there was a decrease in the mean score on the post-test of 3.22 and 3.11 respectively. The results of the sample paired t-test analysis show that the p-value is 0.000, which means there is a significant difference in the effect between giving coconut oil and aloe vera in accelerating the healing of diaper rash in babies.

Ion gradient induced self-powered flexible strain sensor

To cope with energy hazards and reduce frequent battery replacement of strain sensors, various self-powered flexible strain sensors (including piezoelectric, triboelectric and electrochemical types) have developed recent years. However, the piezoelectric and triboelectric strain sensors cannot monitor static strain, and electrochemical strain sensors face the problem of performance degradation. Herein, inspired by ion gradient generators, a self-powered flexible strain sensor based on strain regulated ion gradient strategy is constructed. The sensor consists of elastic yarn coated with carbon nanotubes (CNTs), LiCl-filter paper (FP) and latex tube encapsulation. LiCl-FP with excellent water molecules absorption performance is wrapped on one side of the elastic yarn, forming a high humidity region in the sensor. The part of the elastic yarn that is not covered by LiCl-FP has weak water molecules absorption performance, forming a low humidity region in the sensor. The ions in the sensor move directionally from the high humidity region to the low humidity region, forming an ion gradient and generating voltage/current. The test results indicate that the sensor exhibits a wide strain detection range (0.5%–100%) and good repeatability (1000 times). The strain sensing mechanism can be attributed to the strain regulated ion gradient and the resistance strain effect. In addition, the strain sensing function of the sensor is verified by monitoring respiration. This work opens a new avenue for development of self-powered strain sensor using strain regulated ion gradient.

Acquisition of green algal photobionts enables both chlorolichens and chloro-cyanolichens to activate photosynthesis at low humidity without liquid water.

Cyanobacteria require liquid water for photosynthesis, whereas green algae can photosynthesise with water vapour alone. We discovered that several Lobaria spp. which normally have cyanobacteria as the sole photobiont, in some regions of the trans-Himalayas also harboured green algae. We tested whether green algal acquisition was: limited to high elevations; obtained from neighbouring chloro-Lobaria species; enabled photosynthesis at low humidity. Lobaria spp. were collected from 2000 to 4000 m elevation. Spectrophotometry quantified green algal abundance by measuring chlorophyll b (absent in cyanobacteria). Thalli cross-sections visually confirmed green algal presence. We sequenced gene regions: Lobaria (ITS-EF-1α-RPB2), green algae (18S-RBC-L) and Nostoc (16S). Phylogenetic analysis determined myco-photobiont associations. We used a custom closed-circuit gas exchange system with an infrared gas analyser to measure CO2 exchange rates for desiccated specimens at 33%, 76%, 86% and 98% humidity. Cross-sections revealed that the photobiont layers in putative cyano-Lobaria contained both cyanobacteria and green algae, indicating that they should be considered chloro-cyanolichens. Chloro-Lobaria had no visible cephalodia nor cyanobacteria in the photobiont layer. Chloro-Lobaria and chloro-cyano-Lobaria had comparable levels of chlorophyll b. Chloro-Lobaria usually contained Symbiochloris. Chloro-cyano-Lobaria mainly associated with Parachloroidium and Nostoc; infrequently with Symbiochloris, Apatococcus, Chloroidium, Pseudochlorella, Trebouxia. Sequences from two green algal genera were obtained from within some thalli. Desiccated specimens of every Lobaria species could attain net photosynthesis with light exposure and 33% humidity. CO2 exchange dynamics over a five-day period differed between species. At all elevations, chloro-cyano-Lobaria spp. had abundant green algae in the photobiont layer, but green algal strains mostly differed to those of chloro-Lobaria spp. Both chloro-Lobaria and chloro-cyano-Lobaria were capable of conducting photosynthesis without liquid water. The data strongly suggest that they attained positive net photosynthesis.

Fungal Hyphae on the Assimilation Branches Are Beneficial for Haloxylon ammodendron to Absorb Atmospheric Water Vapor: Adapting to an Extreme Drought Environment.

Research on endophytic fungi in desert plants, particularly the epiphytic or endophytic fungi of leaves, remains limited. In the extremely arid regions of northwest China, the ultra-xerophytic desert plant Haloxylon ammodendron harbors white fungi on its assimilating branches during autumn. The hyphae of these fungi intertwine, both internally and externally, comprising superficial, bridging, and endophytic types. The superficial hyphae attach to the surface of the assimilating branches and continuously grow and intersect, forming a thick layer of felt-like hyphae. This thick, felt-like layer of hyphae facilitates the adsorption of atmospheric water vapor on the surface of the hyphae or the assimilating branches, allowing H. ammodendron to capture atmospheric moisture, even under low humidity. Some superficial hyphae penetrate the cuticle into the epidermis, becoming bridging hyphae, which can rapidly transport water from the outside of the epidermis to the inside. The endophytic hyphae shuttle within the epidermis, achieving rapid water transfer within the epidermis of the assimilating branches. The presence of these three types of hyphae not only enables the assimilating branches of H. ammodendron to achieve rapid water absorption and transmission, but also facilitates the uptake of atmospheric water vapor under low humidity conditions. We discuss the mechanism by which the hyphae promote water absorption from the perspectives of hyphal composition, the formation of felt-like structures, and environmental conditions. We consider the presence of fungal hyphae on the surface of the H. ammodendron assimilating branches as an inevitable ecological process in arid environments. This study provides important theoretical insights into the mechanisms underlying the strong drought resistance of desert plants in extremely arid regions and offers strategies for desertification control.

Computational Fluid Dynamics Process for Front Windshield Mist Deposition and Its Subsequent Demisting

&lt;div&gt;A vehicle’s heating, ventilation, and air-conditioning system plays a dual role in passenger thermal comfort and safety. The functional aspects of safety include the front windshield demist and deicing feature of the system. The thin-film mist is a result of condensation of water vapor on the inner side of the windshield, which occurs at low ambient temperatures or high humidity. This mist deposition depends on the air saturation pressure at the front windshield. Indian regulation AIS-084 defines the experimental setup for testing, which encompasses both the mist deposition and its subsequent demist process. This regulation mandates testing, which occurs at a later stage of product development. This performance validation can be performed using a three-dimensional computational fluid dynamics approach.&lt;/div&gt; &lt;div&gt;Current work summarizes the simulation process for both the mist deposition and the subsequent demisting phenomenon. The complexity of the flow physics is captured via the transient multiphase fluid flow phenomenon subjected to buoyancy effects. This phenomenon is simulated using the Eulerian wall film approach. The wall film deposition of the mist is modeled via species transport. Further, the near-wall thermal effects of surface conduction and heat transfer are simulated by modeling shell conduction layers. Vapor diffusion and relative humidity inside the cabin are modeled using a user-defined function. The process correlation is achieved for two categories of vehicles to establish the process efficacy and robustness. Moving ahead, a design of experiments (DOE) is planned to mitigate the need to simulate mist deposition. The DOE is planning to incorporate deviations in both the input airflow conditions and the imposed ambient conditions. The results from DOE point toward factors that might cause deviations in simulation results with respect to the test. Importantly, the study concludes that the uniform initial thickness assumption of the mist layer can be used for subsequent demist analysis.&lt;/div&gt;

Studying the Role of Soil Factors on Degree of Degradation of DNA of Human Remains

Generating a DNA profile using autosomal Short Tandem Repeat (STR) DNA allele from skeletal remains is a crucial step in the identification process for mass disaster and unidentified person situations. The capacity to extract substantial amounts of relevant DNA from bones, which were highly durable biological components that can withstand soil elements and climatic conditions over long periods of time, would be advantageous. 70 femur male bone samples were collected from two different environmental mass graves (Al-Mahaweel massgrave) in Babil governorate and (Al-Saqlawiya massgrave) in Al-Anbar governorate in Iraq. The DNA from bone samples extracts were assessed by capillary electrophoresis and a standardized set of short tandem repeat (STR) loci are analyzed using Mutiplex 21 STR loci System to allow human identification by matching the profile of the dead individuals with their relatives. From these two different sites; soil samples were collected to analyze and study the different environmental factors and find a relation between the degree of preservation or degradation with these factors like temperature, humidity, salinity, PH and texture of soil and find how these factors can affect on pattern of degradation of DNA profiles. The average of the percentage of the detected alleles in each locus in the two sites; were 87\% for Al-Mahaweel site and 32\% for Al- Saqlawiya site. we found that clay soil, low salt concentration, PH slightly alkaline and low humidity for Al-Mahaweel site; all participate in DNA preservation while the chalky and very high salt concentration of Al- Saqlawiya site soil; all participate in DNA degradation. Predicting the effect of these factors on the quality of the DNA profiles can be helpful in finding better solutions for many complications that may face the process of analyzing samples and finding sufficient informative profiles.

Ecological amplitude and indication potential of mining bees (Andrena spp.): a case study from the post-agricultural area of the Kampinos National Park (Poland)

The mining bee (Andrena spp.) play a key role in ensuring plant and animal diversity. The present study examines their diversity in a post-agricultural landscape exemplified by the Kampinos National Park (KNP), a UNESCO Biosphere Reserve in Poland. The following hypotheses were addressed: (H1) the mining bees demonstrate a narrow ecological amplitude, (H2) there are no indicator species for particular habitats, and (H3) the studied mining bees have the same ecological preferences to those presented in the literature. A total of 40 catch per unit effort samples (CPUE) were collected across various habitats with different soil humidity. Forty-six species were recorded, representing 46% of mining bees and approximately 10% of the known Polish bee fauna. Nineteen of the recorded species (41%) were assigned to CR-NT threat categories, indicating that the national park plays a significant role in preserving mining bee species diversity and their conservation. None of the hypotheses (H1, H2, H3) were confirmed. The mining bees were found to demonstrate a wide ecological amplitude. Surprisingly, habitats located in dry and wet soils were both characterised by high abundance and species richness. Seventeen indicators were distinguished among the dominant and rarer species. Our findings suggest that Andrena nigroaenea and A. ventralis (lower humidity), as well as A. alfkenella and A. minutuloides (higher humidity), have different significant relationships with habitat soil humidity to those reported in the literature.

The strategy of micropore confinement via organic macrocyclic cavities for designing novel high-performance proton exchange membranes

The high-temperature hydrogen proton exchange membrane fuel cell is considered a disruptive technology for future energy applications. However, the weak binding strength between the proton carriers (phosphoric acid molecules) with polymer chains reduces the operational stability and proton transfer efficiency at conditions of high temperature and low humidity. In this work, a strategy of micropore confinement via organic macrocyclic cavities (sulfonic calix[4]arenes, sulfonic calix[8]arenes, sulfonated β-cyclodextrin) was developed for designing novel mixed matrix membranes functioning as high-temperature hydrogen proton exchange membranes. Benefitting from the confined micropores constructed by supramolecular cavities, the obtained mixed matrix membranes showed a higher uptake and retention capability of phosphoric acid as well as lower membrane swelling, yielding an enhanced proton conductivity. The proton conductivity of the mixed matrix membranes was 2–3 times higher while the conductivity attenuation was only 58.6% comparing with neat PBI membrane, (140℃, relative humidity = 0). In addition, due to the good compatibility caused by hydrogen bonding between fillers and polymer chains, the volume swelling was only 14% and the mechanical strength of the obtained mixed matrix membranes increased. We believe the strategy of micropore confinement via organic macrocyclic cavities for designing the novel mixed matrix membranes is thought to be of great significance for the research on high-temperature proton exchange membrane.

A numerical study of heterogeneous nucleation of ice crystals and frost layer growth on horizontal cold surfaces

In engineering applications, the formation and growth of frost layers can significantly affect the normal operation of equipment, leading to undesirable influences. Therefore, it is imperative to understand the frost formation mechanisms as a basis for developing effective anti-frosting and defrosting methodologies. This study proposes a model for the growth of horizontal cold surface frost layers using the classical nucleation theory and the Eulerian multiphase flow model. Compared to numerous models that investigate the frost formation issues using the computational fluid dynamics (CFD) method, our proposed model takes into account the crystal growth period (the heterogeneous nucleation process of ice). The predicted results of the proposed model were found to be in good agreement with the data collected from five related experimental studies. In this regard, the maximum frost layer thickness error was 23.9 % with a mean error of 5.1 %, and the maximum density error was 22.8 % with a mean error of 8.1 %. Compared to existing models in the literature, the proposed model can reduce the maximum thickness and density uncertainties by 17.4 % and 10.2 %, respectively. Additionally, the effects of the surface contact angle and environmental parameters on the nucleation process were analyzed using the established model. It was found that a larger contact angle, higher cold surface temperature, and lower air temperature, humidity, and velocity were unfavorable conditions for supporting the formation and growth of ice crystals. Moreover, the nucleation completion time was shortened with the increase in the moist air supersaturation degree, varying as an exponential function. The findings of this study provide an important theoretical basis for the development of optimizing strategies for anti-frosting and defrosting.

Optimizing anode GDL of polymer fuel cells for improving performance at low humidity

Optimizing anode GDL of polymer fuel cells for improving performance at low humidity

Analysis of the Impact of Environmental Temperature and Humidity on Cotton Fiber Quality During Initial Processing

ABSTRACT This study examines the impact of temperature and humidity on cotton fiber quality during initial processing. Conducted in a Xinjiang cotton ginning mill, we used the USTER HVI1000 to analyze five quality indices: upper half mean length, uniformity, short fiber index, tensile strength, and elongation. Results indicated that temperatures below 13°C increased fiber brittleness, moisture, and significantly reduced length and strength. Optimal conditions were observed at temperatures between 13°C to 20°C with normal humidity, where length and strength were maintained. Above 20°C, the dry environment led to a decrease in these indices. While higher temperatures and lower humidity helped remove impurities and lessen cotton knots, relative humidity below 45% increased static electricity and knots. Despite data limitations, this study moves towards identifying optimal temperature and humidity levels for improving cotton quality during initial processing, providing a theoretical foundation for future enhancements.

Ion gradient induced self-powered flexible pressure sensor

Various self-powered flexible pressure sensors (including piezoelectric, triboelectric and electrochemical types) have attracted great attentions and made significant progresses, but they also have some shortcomings, such as the inability to detect static pressure (piezoelectric and triboelectric types) and performance degradation (electrochemical type). Inspired by the ion gradient power generation mechanism, we propose a self-powered flexible pressure sensor based on pressure regulated ion gradient coupled with piezoresistive effect. The proposed pressure sensor is mainly composed of high humidity region (LiCl-filter paper (FP)) and low humidity region (carbon nanotubes-FP). The results show that the sensor can directly output current signal with a wide pressure range (0.1–100 kPa). Based on the output voltage and current signals and the morphology characterization, the power generation and pressure sensing mechanisms of the sensor are clarified using the ion gradient and piezoresistive effects. In addition, the sensor can be used to identify different respiratory states in combination with machine learning. This work provides a new strategy for constructing self-powered pressure sensor based on pressure regulated ion gradient strategy coupled with piezoresistive effect.

Predicting the lifetime of HJT modules towards the outdoor real-world environment

The high-performance silicon solar cells can be manufactured with the unique amorphous/crystalline heterojunction (HJT) structure. In the field applications of the photovoltaics, the durability of HJT modules has become an issue which gets a lot of attention. In this work, it was found that the ultraviolet-induced (UV-induced) degradation is largely caused by the decrease in short-circuit current, and UV cut-off polyolefin elastomers (POE) can effectively suppress the attenuation rate. Additionally, temperature and humidity also affect the module degradation rate, which was revealed through a series of damp-heat (DH) acceleration tests. From the analytical calculations of the data of UV and DH tests, Arrhenius activation energy of 0.43 eV was successfully derived. Accordingly, the Peck model was applied, which indicates that the lifetime of HJT modules can be predicted in the case of the specific climate parameters, such as temperature, humidity and UV irradiation. Based on this model, lifetime of HJT modules is around 22 years due to its stronger annual UV irradiation of over 72 kWh/m2 and over 80 % relative humidity (RH) in Hainan. By contrast, fortunately, lifetime of over 30 years is predicted at the lower UV irradiation of 48 kWh/m2 in Daqing and lower humidity of less than 55%RH in Ningxia, which are the typical photovoltaic climate zones of China.