External Humidity Research Articles

Influence of Internal and External Humidity Difference on the Distribution Characteristics of the Carbonated Zone of Cement-Based Materials

This paper aims to investigate the effect of internal and external humidity differences on the distribution characteristics of the carbonated zone of cement-based materials. Carbonation tests with ambient humidity and pore water saturation as the influencing factors were implemented. The calcite content of the mortar along the depth of carbonation was presented. The rationality of the carbonation model was verified by the calcite test results, and the effect of internal and external humidity differences on the carbonation zone distribution of cement-based materials was analyzed by the model. The results showed that the test results of calcium carbonate and the simulation results can clearly distinguish the completely and partly carbonated zones of cement-based materials. The effect of pore water saturation on the distribution of the carbonated area was conspicuous, but the difference in pore water saturation cannot change the variation of the extent of the carbonated zone with ambient humidity. The change regularities of fully and partly carbonated zones with humidity differences were obtained.

Characteristics of structural morphological changes of the liver depending on the prescription of death coming

The purpose of the work is to analyze the literature data devoted to the study of postmortem morphological changes in liver tissue and their use to determine the prescription of death. Postmortem changes are based on the processes of postmortem redistribution of blood and autolysis, the speed and severity of development of which depends primarily on the lifetime pathology, as well as external temperature and humidity during storage of the corpse. The onset of biological death naturally entails the development of postmortem changes in the liver, manifested by a decrease in temperature, violations of the structure of organelles, cells and organ tissue as a whole. The determination and evaluation of developing postmortem morphological changes is necessary both for differential diagnosis with lifetime-developed pathological processes, and for determining the prescription of death coming. This necessitates research to study the features of the development of postmortem changes and to develop ways to assess them to determine the prescription of death coming.

Bakteriozna plamenjača kruške

Fire blight of pear, caused by the bacterium Erwinia amvlovora, is the most significant bacterial disease of this fruit species, both in our country and worldwide. Epidemics, although sporadic, are often devastating depending on external conditions, primarily temperature and humidity, the amount of initial inoculum and the sensitivity of the host variety. Therefore, the disease can be either catastrophic or of secondary importance, depending on the year and the cultivar being grown. The ability of the bacterium to multiply and spread rapidly in host plants makes it very difficult to suppress and control. Protection against fire blight is not simple, and involves combination of preventive agrotechnical, mechanical, sanitary and Chemical measures. The most effective Chemical control measure is application of copper compounds and antibiotics, but their application contributes to environmental pollution and development of resistant E. amylovora populations. Therefore, there is a great need to find alternatives to protect pear and other hosts from this bacterium. Although fire blight was first observed almost two and a half centuries ago, dne to its specificity, it continues to occupy attention of the experts with undiminished intensity, and wherever it appears, it creates great problems in pear production. Therefore, extraordinary efforts of both fruit growers and plant protection experts are necessary in order to prevent and mitigate the consequences ofthis very harmful bacterial disease.

Automatic control system for automatic maintenance of microclimate in vegetable storages

The paper presents an automatic control system for automatic maintenance of the desired microclimate in the storage, controlled by a computer. The state of the microclimate in the vegetable store is monitored with the product and channel temperature sensors and internal and external humidity sensors. This system will automatically control the ventilation parameters at different times of the year, and regulate humidity conditions.

The Effect of In-Situ-Generated Moisture on Disproportionation of Pharmaceutical Salt.

Pharmaceutical salts are ubiquitously present in the market given their benefits in optimizing the critical properties of an active pharmaceutical ingredient (API). Achieving these benefits requires careful selection and understanding of the salt form of choice. Stability is especially critical here, as salts are susceptible to disproportionation. Several studies have shown the impact of moisture on disproportionation, with more focus on external humidity (moisture coming from outside the system). This work, on the other hand, is systematically designed to study the impact of moisture generated in situ (moisture produced within the system). To that end, an in-house developed compound 1 was selected as our salt API, and its disproportionation was studied in blends (binary and prototype) with hydrated model excipient─trisodium phosphate dodecahydrate (TSPD). TSPD possesses 12 water molecules, which could get released when triggered with enough energy (confirmed by thermogravimetric analysis and humidity studies). As a control for this study, similar blends were prepared with anhydrous trisodium phosphate (TSP), which has comparable properties to TSPD but lacks water. Overall, significant disproportionation was observed in TSPD blends exposed to 40 °C or 70 °C in a closed system; while no disproportionation was observed when the system was left open due to the escape of the moisture generated in situ. The API also remained intact for the blends with anhydrous TSP, as expected. Meanwhile, stressing at 40 °C/75%RH condition resulted in significant disproportionation for both TSPD and TSP blends due to the exposure to external humidity. Hydrated excipients are normally used in drug development, and this work stresses the need for probing the impact from within the system when such excipients are utilized with salt API. This will help fully unravel the overall effect of moisture on the drug, which is relevant downstream when selecting processing conditions, packaging, and so forth.

Characterization of Polyurethane Shape Memory Polymer and Determination of Shape Fixity and Shape Recovery in Subsequent Thermomechanical Cycles.

Multifunctional polyurethane shape memory polymers (PU-SMPs) have been of increasing interest in various applications. Here we report structure characterization, detailed methodology, and obtained results on the identification of functional properties of a thermoset PU-SMP (MP4510) with glass transition temperature of 45 °C. The stable, chemically crosslinked network of this thermoset PU-SMP results in excellent shape memory behavior. Moreover, the proximity of the activation temperature range of this smart polymer to room and body temperature enables the PU-SMP to be used in more critical industrial applications, namely fast-response actuators. The thermomechanical behavior of a shape memory polymer determines the engineering applications of the material. Therefore, investigation of the shape memory behavior of this class of commercial PU-SMP is of particular importance. The conducted structural characterization confirms its shape memory properties. The shape fixity and shape recovery properties were determined by a modified experimental approach, considering the polymer's sensitivity to external conditions, i.e., the temperature and humidity variations. Three thermomechanical cycles were considered and the methodology used is described in detail. The obtained shape fixity ratio of the PU-SMP was approximately 98% and did not change significantly in the subsequent cycles of the thermomechanical loading due to the stability of chemical crosslinks in the thermoset materials structure. The shape recovery was found to be approximately 90% in the first cycle and reached a value higher than 99% in the third cycle. The results confirm the effect of the thermomechanical training on the improvement of the PU-SMP shape recovery after the first thermomechanical cycle as well as the effect of thermoset material stability on the repeatability of the shape memory parameters quantities.

Quasi-acoustic impedance matching distributed opto-mechanical sensor with aluminized coating optical fibers.

The uncoated single-mode fiber has been extensively researched as an opto-mechanical sensor since it can achieve substance identification of the surrounding media by exciting and detecting transverse acoustic waves via forward stimulated Brillouin scattering (FSBS), but it has the danger of being easily broken. Although polyimide-coated fibers are reported to allow transverse acoustic waves transmission through the coating to reach the ambient while maintaining the mechanical properties of the fiber, it still suffers from the problems of hygroscopic property and spectral instability. Here, we propose a distributed FSBS-based opto-mechanical sensor using an aluminized coating optical fiber. Benefiting from the quasi-acoustic impedance matching condition of the aluminized coating and silica core cladding, aluminized coating optical fibers not only have stronger mechanical properties and higher transverse acoustic wave transmission efficiency but also have a higher signal-to-noise ratio, compared with the polyimide coating fibers. The distributed measurement ability is verified by identifying air and water around the aluminized coating optical fiber with a spatial resolution of 2 m. In addition, the proposed sensor is immune to external relative humidity changes, which is beneficial for liquid acoustic impedance measurements.

Life-stage dependent response of the epiphytic lichen Lobaria pulmonaria to climate

Lichens are poikilohydric organisms, whose internal water content tends to reflect external humidity conditions. After drying, they can reactivate their metabolic activity through water vapor uptake or liquid water input. Thus, lichen water-related functional traits are important as they are involved in the duration of the hydrated period. Models predicting the effect of environmental conditions on lichens are based mainly on the presence or absence of adult thalli. Nevertheless, ecological conditions required by lichens might vary during their life cycle, for example during propagule establishment or in the first stages of thallus development. Little is known about the different ecological requirements at the different development stages in lichens. In this work, we measured water holding capacity (WHC) and specific thallus mass (STM) of adult and juvenile thalli of the model species Lobaria pulmonaria along a climatic gradient to constrain the process-based model LiBry. The LiBry model allows accounting for the productivity of lichens with different physiological strategies under various environmental conditions. We simulated the activity and performance of adult and juvenile thalli in 9 regions of Italy and Corsica. The model was used to test if adult thalli of L. pulmonaria have a higher survival probability due to their higher aerodynamic resistance. In the current climatic condition, the LiBry model predicts a higher survival probability of adults with decreasing absolute survival rates of both life stages with increasing temperature. Adult thalli also result in having higher active time, STM, and relative growth rate (RGR). We discuss the main implications of our simulation outputs, provide future perspectives and possible implementations of the LiBry model.

Influence of rapid curing methods on concrete microstructure and properties: A review

Along with the construction industrialization degree, precast concrete is being utilized more and more frequently in construction to speed up the process and guarantee the quality of structural concrete. In order to make the precast concrete reach the required strength quickly and speed up the turnover of formwork, various rapid concrete curing methods emerged. Currently steam curing, direct electric curing, and microwave curing are the widely studied rapid curing methods. Rapid curing methods could promote early strength growth by changing the internal and external temperature and humidity of concrete, but may lead to late strength shrinkage, increased internal micro-cracks, coarsening of pore structure and other problems. Based on the comprehensive analysis of the curing principles of the three rapid curing methods, this paper reviews the effects of the three rapid curing methods on the hydration process, properties, and microscopic pore structure of concrete. The shortcomings of different rapid curing methods, and the topics of future researchs are also included.

Optical fiber hydrogen sensor based on self-assembled PDMS/Pd-WO3 microbottle resonator

In this paper, a new optical fiber hydrogen(H2) sensor based on a self-assembled microbottle resonator was proposed. The self-assembled microbottle was simply obtained by coating the single-mode fiber (SMF) with an internal composite material layer of palladium-tungsten trioxide (Pd-WO3) that was sensitive to H2 and an outer organic polymer material layer of polydimethylsiloxane (PDMS) with a significant thermal response. The microbottle resonator was further fabricated by coupling a tapered fiber with the self-assembled microbottle to excite whispering gallery mode (WGM). When the WGM resonator is exposed to H2, H2 molecules penetrate the PDMS and undergo redox reaction with the Pd-WO3. After the PDMS absorbs the reaction heat, its volume and refractive index will change, along with the wavelength shift of the WGM resonator. Therefore, a simple and low-cost H2 sensor is realized by observing the shift of resonance wavelength. Experimental results showed that the hydrogen sensor had a maximum sensitivity of − 3.091 nm/% at 25 ℃. And the resonance wavelength just shifted a small distance when the relative humidity increased from 22.87 % to 84.59 % or the temperature rose from 20.2 ℃ to 30 ℃, which indicated the sensor had preferable resistance to disturbances of external humidity and temperature.

Preparation and performance of polypyrrole modified filter paper humidity sensor by in situ polymerization

Polypyrrole (PPy) has high electrical conductivity, good environmental stability, and reversible electrochemical redox characteristics, which makes PPy responsive to changes in environmental humidity values. In this work, a humidity sensor with a good response to humidity was prepared using in situ polymerization of PPy in filter paper doping with acetic acid. A possible sensing mechanism of conductive polymers is proposed and the conjecture is verified by experiments. The results demonstrated that the PPy/filter paper-based humidity sensor provides an electron migration channel with the capability of detecting the relative humidity. External humidity stimulation can regulate the electrochemical reaction of PPy. The reduction reaction occurs near the water side to generate the nucleophilic product OH–. The PPy system loses electrons to form carrier directional channels, resulting in changes in the output voltage measured between the two electrodes. The PPy/filter paper-based humidity sensor exhibits the moisture dependent voltage response over a wide range from a relative humidity of 11–98%, and a response/recovery time of 43/51 s as it was placed between relative humidity of 33% and 98%. In addition, unlike the traditional sensing mechanism, the voltage sensing mechanism raised here shows self-powered ability with no need for an additional power unit. This provides a new idea for self-powered sensor devices, and this sensor shows good performance in non-contact sensing applications such as breath detection.

Study on electrochemical characteristics of reinforced concrete corrosion under the action of carbonation and chloride

Considering parameters of corrosion area ratio and mass loss degree, the half-cell potential method and linear polarization method were applied to study the corrosion state of steel bars under the influence of carbonation, chloride salt and compound environmental action. X-ray photoelectron spectroscopy (XPS) was used to measure steel corrosion under coupling action and the effect of sodium nitrite rust inhibitor in the compound environment was studied. The results show that the corrosion rate of steel under carbonation, chloride salt and compound environment increases in the beginning and then decreases. In the chloride environment, sufficient moisture inside the concrete at the initial stage of curing induces a faster corroding. With the destruction of the passive film on the surface of the steel bars together with the balance of internal and external humidity, the corrosion rate tends to stabilize. At the following curing stage, the corrosion rate decreases as the degree of steel corrosion increases and the corrosion layer is formed. Carbonation reduces the alkalinity around the passive film and damages the passive film, which accelerates the corrosion happening. The following development of the corrosion layer of steel bars limits the corrosion rate. The corrosion degree in the compound environment is more serious than that under the condition of single factor action. Under electrochemical action, the order of product components resulting from steel corrosion are Fe2O3, Fe3+-Ca2SiO4 and FeO from high to low. Nitrite oxidizes the unstable Fe2+ into stable Fe3+ and precipitates on the surface of the steel to form a passivation film, which has a good anti-rust effect.

CFD Study of a Tunnel-Ventilated Compost-Bedded Pack Barn Integrating an Evaporative Pad Cooling System.

Simple SummaryIt is known that improving the welfare of cows increases dairy productivity. A compost-bedded pack barn equipped with evaporative cooling pads to regulate the inside environmental conditions of dairy seems to be a synergic combination to improve substantial the welfare in dairy facilities. However, there is a lack of information about both techniques working together. A computational model of a tunnel-ventilated compost-bedded pack barn with an evaporative pad cooling system was developed to know the spatial distribution of temperature, relative humidity and velocity of the air inside the barn. These variables allowed us to compute a thermal stress index for dairy cattle to identify the geometric characteristics and operative conditions of the evaporative pad cooling that provide the best environmental conditions inside the barn according to the outside environmental conditions.Evaporative cooling is one of the most efficient techniques to reduce heat stress in cows in agricultural facilities. Additionally, compost-bedded pack barn has been shown to improve the welfare and production of cows. Two techniques were combined and analysed by developing a computational fluid dynamics (CFD) model of a tunnel-ventilated compost-bedded packed barn that integrated the heat and airflow dynamics of an evaporative pad cooling system. This allowed us to study the distribution of dry-bulb temperature, relative humidity and airflow velocity inside the barn based on the external environmental conditions, thickness of the pad, water temperature and specific manufacturer characteristics of the pad, providing optimal cooling pad location, size and operating conditions in the barn. Employing experimental data the CFD model was validated showing good agreement. The Equivalent Temperature Index for dairy Cattle (ETIC) was used to determine the level of stress of the cows considering the airflow velocity. It was found a moderate stress due to high relative humidity and low airflow velocity. From the predicted results, it was recommended to increase the airflow velocity above 3 m s when simultaneously the external dry-bulb temperature and relative humidity exceed 30 °C and 55%, respectively, simultaneously. Additionally, installation of baffles at the pad outlet to drive the airflow to the floor was suggested to improve the drying of the compost-bedded closed to the pads, where a low airflow velocity region was established.

(Digital Presentation) Stable Organic Passivated Carbon Nanotube-Silicon Solar Cells with an Efficiency of 22%

The organic passivated CNT/Si solar cell is a new type of low-cost, high-efficiency solar cell, with challenges concerning the stability of the organic layer used for passivation. In this work, the stability of the organic layer is studied with respect to the internal and external (humidity) water content and additionally long-term stability for low moisture environments. It is found that the organic passivated CNT/Si complex interface is not stable, despite both the organic passivation layer and CNTs being stable on their own and is due to the CNTs providing an additional path for water molecules to the interface. With the use of a simple encapsulation, a record power conversion efficiency (PCE) of 22% is achieved and a stable photovoltaic performance is demonstrated. This work provides a new direction for the development of high-performance/lost-cost photovoltaics in the future and will stimulate the use of nanotubes materials for solar cells applications.

Neural Network Model for Greenhouse Microclimate Predictions

Food production and energy consumption are two important factors when assessing greenhouse systems. The first must respond, both quantitatively and qualitatively, to the needs of the population, whereas the latter must be kept as low as possible. As a result, to properly control these two essential aspects, the appropriate greenhouse environment should be maintained using a computational decision support system (DSS), which will be especially adaptable to changes in the characteristics of the external environment. A multilayer perceptron neural network (MLP-NN) was designed to model the internal temperature and relative humidity of an agricultural greenhouse. The specific NN uses Levenberg–Marquardt backpropagation as a training algorithm; the input variables are the external temperature and relative humidity, wind speed, and solar irradiance, as well as the internal temperature and relative humidity, up to three timesteps before the modeled timestep. The maximum errors of the modeled temperature and relative humidity are 0.877 K and 2.838%, respectively, whereas the coefficients of determination are 0.999 for both parameters. A model with a low maximum error in predictions will enable a DSS to provide the appropriate commands to the greenhouse actuators to maintain the internal conditions at the desired levels for cultivation with the minimum possible energy consumption.

Indirect solar dryer with a single compartment for food drying. Application to the drying of the pear

This work presents the experimental results relating to agri-food drying in an indirect solar dryer with a single compartment. This compartment has four facades. Which consist of: glazed cover above and aluminium walls at the bottom and an air layer bounded by them. The drying chamber is under the aluminium walls. The layers of glass, air and walls subjected to the solar flux act as an absorber and play an important role to enhance the heat transfer in the drying chamber.The designed dryer is a single compartment with a south-oriented roof. Moreover, this roof has two inclined surfaces with optimal angles of 50° and 34° from the horizontal plane to absorb the maximum solar irradiation during the year. This dryer is made up in the solar energy and environmental laboratory of the Faculty of Sciences of Rabat city (longitude: 6°49′57″, latitude: 34°00′47″).After this choice, the study presents the thermal and economic performances of the designed dryer. Firstly, in terms of thermal performance, the experimental tests show that the relative humidity inside the dryer can decrease by up to 10% compared to an external relative humidity between 70 and 90%, and the average temperature inside the dryer was 50 °C, in comparison to the average ambient temperature is 25 °C. These thermal performances allowed the pear to dry just after 24 h. Secondly, in terms of economic cost, this new design of the solar dryer is less expensive than conventional two-compartment solar dryers and encourages its use by the local producer.

Low humidity altered the gene expression profile of keratinocytes in a three-dimensional skin model.

The skin is constantly exposed to various external stimuli including humidity variations. Low humidity affects skin properties such as decreased water content of the stratum corneum, reduced skin elasticity, and itching. However, the effects of humidity on the skin cells are not completely understood. This study aimed to investigatehow low humidity affects keratinocytes of the skin. In the present study, the effects of dry environment on the gene expression profile of epidermal keratinocytes were demonstrated using a three-dimensional skin model (3D-skin), composed of keratinocytes. Exposure of 3D-skin to low humidity (relative humidity ~ 10%) increased the expression levels of various genes, including those related to signal transduction and immune system. Accordingly, p38 mitogen-activated protein kinase (MAPK) signaling in keratinocytes of the 3D-skin was activated in response to low humidity for 30min. Additionally, several chemokines, such as chemokine (C-X-C motif) ligand 1 (CXCL1) and Chemokine (C-C motif) ligand 20 (CCL20), were up regulated after 3h of exposure to low humidity. We hypothesize that increased chemokine production may affect the immune system of the whole skin through chemoattractants. Our findings imply that keratinocytes sense low humidity and resultant activation of some cell-signaling pathways leads to variations in gene expression profiles including various chemokines. We provide evidence that keratinocytes adapt to external humidity variations.

Efficacy of alternative cooling devices used for insulin storage without refrigeration under hot-humid environment

Background Insulin is temperature sensitive as high temperatures reduce its potency. Refrigeration for insulin storage is still needed but households in remote areas do not have refrigerators. Also, the electricity supply is usually affected by natural disasters. We aim to examine the temperature-reducing efficacy of cooling devices in hot-humid conditions. Methods Five cooling devices, (1) earthen jar filled with water, (2) earthen jar filled with soil, (3) two clay pots, gap filled with wet soil, (4) two clay pots, gap filled with wet sand, and (5) commercial cooling wallet were used in this study. External and internal temperatures were monitored by the temperature logger between October 2019 and September 2020 in Narathiwat, Thailand. Cooling efficacy was assessed by average absolute temperature reduction and relative cooling effect. Results Mean external temperature and humidity were 27.3 ± 1.5 °C and 78.2 ± 7.1%RH. The mean differences between the external and internal temperatures were; device (1) −0.1 ± 0.6 °C (p = NS), (2) 0.0 ± 0.8 °C (p = NS), (3) −1.7 ± 0.9 °C (p < .0001), (4) −2.0 ± 0.9 °C (p < .0001), and (5) −1.8 ± 0.9 °C (p < .0001). Device no. 3, 4, and 5 achieved a constant temperature reduction. The most efficacious device was device no. 4 with a relative cooling effect of 63.6% better than the cooling wallet (57.7%, p = .003). All devices were more efficacious at lower humidity levels. Conclusions Traditional low-cost devices, such as clay pots, reduce storage temperatures to or close to room temperature in hot-humid climates. This study provides some guidance for insulin storage in hot-humid environments.

Bio-inspired water resistant and fast multi-responsive Janus actuator assembled by cellulose nanopaper and graphene with lignin adhesion

Flexible actuators with responses to various environmental stimuli have attracted great attention, but the issues of weak layer-to-layer bonding and low water resistance of cellulose-based actuators severely restrict their practical application. Herein, inspired by the internal structure of lignocellulose and reversible opening movement of pine cones by external humidity stimuli, a novel Janus film consisting of the insulated lignin-containing cellulose nanopaper (CNP) layer and the conductive reduced graphene oxide (rGO) layer was delicately designed and well fabricated through lignin adhesion between the two layers. Characterization showed that the obtained Janus film with a tensile strength of 141 MPa could be used as a flexible actuator, which could be operated based on water absorption and dehydration of the CNP layer as well as the light-to-heat conversion and high conductivity of rGO layer. Thus, the as-fabricated Janus film with excellent durability (folding resistance (>1000 times), good wet stability, and durable electrical actuation (>500 cycles)) had quick multi-responses to humidity, near-infrared radiation and electrical stimulation. Particularly, the resultant Janus film had the fastest response speed (1.875°/s/V) under the electrical stimuli compared to the reported carbon/polymer-based flexible actuators with comparable weights. Therefore, this CNP-based Janus film can be potentially used in many fields such as humidity sensor, bionic artificial arm/driving motor, and it could be helpful to develop facile and environmentally friendly strategies for the construction of multi-responsive Janus actuator/intelligent devices.

Disordered-nanoparticle-based etalon for ultrafast humidity-responsive colorimetric sensors and anti-counterfeiting displays.

The development of real-time and sensitive humidity sensors is in great demand from smart home automation and modern public health. We hereby proposed an ultrafast and full-color colorimetric humidity sensor that consists of chitosan hydrogel sandwiched by a disordered metal nanoparticle layer and reflecting substrate. This hydrogel-based resonator changes its resonant frequency to external humidity conditions because the chitosan hydrogels are swollen under wet state and contracted under dry state. The response time of the sensor is ~104 faster than that of the conventional Fabry-Pérot design. The origins of fast gas permeation are membrane pores created by gaps between the metal nanoparticles. Such instantaneous and tunable response of a new hydrogel resonator is then exploited for colorimetric sensors, anti-counterfeiting applications, and high-resolution displays.