High Humidity Levels Research Articles

Effects of climate change on patients with respiratory and cardiovascular conditions.

Climate change is one of the most significant global challenges and is already having detrimental effects on people's health. Pollution levels and ambient temperatures continue to increase, resulting in higher levels of humidity and pollen production. These environmental threats can affect many vulnerable patients, particularly those with respiratory and cardiovascular conditions, and nurses have a crucial role in raising awareness of the health implications of climate change. This article explores the pathophysiological effects of climate change on patients with asthma, chronic obstructive pulmonary disease and cardiovascular disease, and aims to enhance nurses' understanding of the health challenges of climate change.

Dual Improvement in Sensitivity and Humidity Tolerance of a NO2 Sensor Based on 3-Aminopropyltriethoxysilane Self-Assembled Monolayer-Functionalized SnSe2 for Explosive Photolysis Gas Detection

Explosives can be analyzed for their content by detecting the photolytic gaseous byproducts. However, to prevent electrostatic sparking, explosives are frequently preserved in conditions with low temperatures and high humidity, impeding the performance of gas detection. Thus, it has become a research priority to develop gas sensors that operate at ambient temperature and high humidity levels in the realm of explosive breakdown gas-phase detection. In this work, 3-aminopropyltriethoxysilane (APTES) self-assembled monolayer-functionalized tin diselenide (APTES-SnSe2) nanosheets were synthesized via a facile solution stirring strategy, resulting in a room-temperature NO2 sensor with improved sensitivity and humidity tolerance. The APTES-SnSe2 sensor with moderate functionalization time outperforms the pure SnSe2 sensor in terms of the response value (317.51 vs 110.98%) and response deviation (3.11 vs 24.13%) under humidity interference to 500 ppb NO2. According to density functional theory simulations, the stronger adsorption of terminal amino groups of the APTES molecules to NO2 molecules and stable adsorption energy in the presence of H2O are the causes of the improved sensing capabilities. Practically, the APTES-SnSe2 sensor achieves accurate detection of photolysis gases from trace nitro explosives octogen, pentaerythritol tetranitrate, and trinitrotoluene at room temperature and various humidity levels. This study provides a potential strategy for the construction of gas sensors with high responsiveness and antihumidity capabilities to identify explosive content in harsh environments.

Experimental Investigation on Desert Cooler Using Different Cooling Pad Materials

Abstract: Desert coolers are important in society, especially in arid regions with hot and dry climates. They provide a costeffective and energy-efficient alternative to air conditioners, which can be expensive to operate and maintain. Desert coolers use natural cooling mechanisms such as evaporation to cool the surrounding air, which makes them more environmentally friendly than air conditioners. In this case, the cooling materials being considered are coconut coir, wood wool, and honeycomb mesh. This involves constructing a desert cooler with a removable cooling pad compartment to allow for the insertion and removal of the different cooling materials. Install each of the cooling materials in the cooler one at a time and record the temperature and humidity of the air passing through the cooler over a set period of time. Compare the results obtained from each of the cooling materials to determine which one provides the most effective cooling. Honeycomb has been found to have excellent water absorption and retention capacity, which helps in maintaining a high level of humidity in the air passing through the cooler, resulting in better cooling. Honeycomb mesh, on the other hand, has a large surface area and a complex structure that enhances the evaporation process and improves the cooling efficiency. While wood wool is also a popular cooling material used in desert coolers, its efficiency may not be as high as coconut coir or honeycomb mesh. However, the choice of the most efficient cooling material can also depend on other factors such as availability, cost, and environmental impact. Overall, the selection of the most efficient cooling material for a desert cooler may require careful consideration of several factors.

Experimental Analysis of Aluminium Hybrid Composite with Various Operating Conditions

This present study deals with the fabrication of Al7075/B4C/HBN metal matrix hybrid composite and investigation of its tribological and mechanical behaviour. The aluminium alloy was reinforced with Hexagonal boron nitride (HBN) with various weight fraction (0%,2%,3%,4%) by keeping Boron carbide (B4C) constant at 3%. Stir casting process was used for the fabrication of the composite. Wear experiment was conducted on pin-on-disc tester using four process parameters such as applied load (10N, 20N, 30N and 40N), sliding velocity (1m/s, 2m/s, 3m/s, 4m/s), temperature (25oC, 50oC, 100oC, 150oC) and percentage of reinforcement (0,2,3,4 HBN). The results indicated that the mechanical properties of the composite material were reduced at high temperatures. Hardness of the composites increases while increase the wt % of HBN. Hardness is minimum at 3rd composition. However, at high temperatures and humidity levels, some debonding was observed, which could reduce the mechanical properties of the material. Overall, the experimental analysis highlights the importance of considering the operating conditions when designing and using aluminum hybrid composites for various applications.

An Efficient Ambient-Moisture-Driven Wearable Electrical Power Generator.

Existing devices for generating electrical power from water vapor in ambient air require high levels of relative humidity (RH), cannot operate for prolonged periods, and provide insufficient output for most practical applications. Here a heterogeneous moisture-driven electrical power generator (MODEG) is developed in the form of a free-standing bilayer of polyelectrolyte films, one consisting of a hygroscopic matrix of graphene oxide(GO)/polyaniline(PANI) [(GO)PANI] and the other consisting of poly(diallyldimethylammonium chloride)(PDDA)-modified fluorinated Nafion (F-Nafion (PDDA)). One MODEG unit (1 cm2 ) can deliver a stable open-circuit output of 0.9V at 8µA for more than 10h with a matching external load. The device works over a wide range of temperature (-20 to +50 °C) and relative humidity (30% to 95% RH). It is shown that series and parallel combinations of MODEG units can directly supply sufficient power to drive commercial electronic devices such as light bulbs, supercapacitors, circuit boards, and screen displays. The (GO)PANI:F-Nafion (PDDA) hybrid film is embedded in a mask to harvest the energy from exhaled water vapor in human breath under real-life conditions. The device could consistently generate 450-600mV during usual breathing, and provides sufficient power to drive medical devices, wearables, and emergency communication.

16 Advanced Solutions for Comprehensive Ambient Air Monitoring

Abstract Growing concerns over harmful exposure to low levels of hazardous air pollutants has led to increasingly demanding volatile organic compound (VOC) monitoring programs. Regulations are evolving to increase monitoring frequency, expand the list of target compounds and set lower detection limits in ambient air. Alongside this ambient and indoor air research continues to identify new, challenging compounds. There have long been specific standard methods and regulations for subsets of compounds, each using different instrumentation. For example method TO-15 for air toxics requires TD-GC-MS, ozone precursors monitoring uses TD-GC-FID and aldehydes are sampled with DNPH cartridges, analyzed by HPLC. Each compound set has its own challenges. Even so there is a drive to combine all three analyses into a single analytical run with the possibility of monitoring in online and offline. Additional considerations are high levels of humidity and large sample volumes, required to meet lower reporting limits. These require sophisticated trapping and water management techniques. As such removal of water from canister and on-line samples without loss of polar species is paramount for successful analysis of the Ozone Precursors, Air Toxics and oxygenated VOCs. This presentation will address the challenges associated with this complex compound list and show how confident identification and quantitation, with maximum sensitivity, can be achieved using state of the art pre-concentration technology. The cryogen-free methodology allows remote, on-line analysis or off-line canister sampling, all with a sample-to-sample cycle time of <60 minutes, significantly reducing equipment overhead and analysis times whilst enhancing insight into air quality.

Room-Temperature NO2 Sensing of CVD-Modified WS2–WSe2 Heterojunctions

Two-dimensional (2D) semiconducting heterojunction chemical sensors are in high demand because of their enhanced response, stability, and selectivity. However, fine-tuning heterojunctions using vapor deposition growth still needs further research. Our present study focuses on the ambient pressure chemical vapor deposition (CVD) synthesis of hexagonal tungsten sulfide-tungsten selenide (WS2–WSe2) p–p heterojunctions (as a 2D–2D arrangement). We use the liquid-phase exfoliation method to disperse bulk WS2 and WSe2 and decorate large flakes of WS2 with smaller WSe2 nanosheets in CVD. Electron microscopy and related surface investigations reveal their homogeneity on drop-casting. Two drops from the exfoliated heterojunction dispersion were drop-cast on a transducer to study the NO2 response and related sensing properties. The sensor showed long-term stability (>2 months), even at high humidity levels (40–90%). The gas-sensing properties of this layered p–p heterojunction-based nanocomposite strongly suggest an affinity toward NO2 gas, leading to improved response, high stability, independent of humidity effects, and high selectivity.

Humidity's Role in Heat-Related Health Outcomes: A Heated Debate.

As atmospheric greenhouse gas concentrations continue to rise, temperature and humidity will increase further, causing potentially dire increases in human heat stress. On physiological and biophysical grounds, exposure to higher levels of humidity should worsen heat stress by decreasing sweat evaporation. However, population-scale epidemiological studies of heat exposure and response often do not detect associations between high levels of humidity and heat-related mortality or morbidity. These divergent, disciplinary views regarding the role of humidity in heat-related health risks limit confidence in selecting which interventions are effective in reducing health impacts and in projecting future heat-related health risks. Via our multidisciplinary perspective we seek to a) reconcile the competing realities concerning the role of humidity in heat-related health impacts and b) help ensure robust projections of heat-related health risks with climate change. These objectives are critical pathways to identify and communicate effective approaches to cope with present and future heat challenges. We hypothesize six key reasons epidemiological studies have found little impact of humidity on heat-health outcomes: a) At high temperatures, there may be limited influence of humidity on the health conditions that cause most heat-related deaths (i.e., cardiovascular collapse); b) epidemiological data sets have limited spatial extent, a bias toward extratropical (i.e., cooler and less humid), high-income nations, and tend to exist in places where temporal variations in temperature and humidity are positively correlated; c) analyses focus on older, vulnerable populations with sweating, and thus evaporative, impairments that may be further aggravated by dehydration; d) extremely high levels of temperature and humidity (seldom seen in the historical record) are necessary for humidity to substantially impact heat strain of sedentary individuals; e) relationships between temperature and humidity are improperly considered when interpreting epidemiological model results; and f) sub-daily meteorological phenomena, such as rain, occur at high temperatures and humidity, and may bias epidemiological studies based on daily data. Future research must robustly test these hypotheses to advance methods for more accurate incorporation of humidity in estimating heat-related health outcomes under present and projected future climates. https://doi.org/10.1289/EHP11807.

Water and heat recovery for greenhouses in cold climates using a solid sorption system

Greenhouses are basically used to create a protected growing environment for crops. In winter climates, cold air temperature and high humidity level are two major problems for greenhouse production, which induce plant diseases and yield losses. In this research, we proposed a climate control system which integrates solid sorption and sensible thermal storage. During the sorption phase, indoor vapor was captured by sorbents while sorption heat was used to increase the air temperature. During the desorption phase, vapor was released and condensed into liquid water. Heat exchanged through the water-cooling condenser was recovered and stored for nocturnal space heating. In the comparative filed experiments, pure silica gels (SG) and composite sorbents CaCl2@SG were chosen as sorbent materials, respectively. During experiments using SG, the averaged nocturnal air temperature was increased by 3.23 °C and the averaged nocturnal relative humidity was decreased by 16.91%. During experiments using CaCl2@SG, the changes were 2.58 °C and 17.39%, respectively. Moreover, CaCl2@SG significantly decreased the averaged humidity ratio by 0.40 g/kg, while SG imposed tiny effect on this parameter. The energy-saving effect of the prosed system was further discussed through simulation.

MOF-801/Graphene Adsorbent Material for Greenhouse Climate Control System—Numerical Investigation

Greenhouses with efficient controlled environment offer a promising solution for food security against the impacts of increasing global temperatures and growing water scarcity. However, current technologies used to achieve this controlled environment consume a significant amount of energy, which impacts on operational costs and CO2 emissions. Using advanced metal organic framework materials (MOFs) with superior water adsorption characteristics, this work investigates the development of a new technology for a greenhouse-controlled environment. The system consists of MOF coated heat exchanger, air to air heat exchanger, and evaporative cooler. A three-dimensional computational fluid dynamics (CFD) model was developed using COMSOL software and experimentally validated for the MOF-801/Graphene coated heat exchanger (DCHE) to determine the best cycle time and power input. It was found that using desorption time of 16 min and power input of 1.26 W, the maximum water removal rate was obtained from MOF-801/Graphene of 274.4 g/kgMOF/W.hr. In addition, an overall mathematical model for the greenhouse climate control was developed and used to investigate the effects of air humidity and velocity on the input air conditions to the greenhouse. Results showed that with high relative humidity levels of 90% in the greenhouse can be conditioned to reach the required relative humidity of 50%.

Properties of Autoclaved Aerated Concrete in Different Curing Conditions: A Review

Abstract: Autoclaved aerated concrete (AAC) has many benefits for structures, such as heat insulation, sound insulation, fire resistance, reduced dead weight, and many more. AAC products include blocks, wall panels, floor and roof panels, and lintels. Besides its insulating capability, one of AAC's advantage in construction is its quick and easy installation since the material can be routed, sanded, and cut to size on-site using standard carbon steel band saws, hand saws, and drills. Although AAC has been produced for many years, there are still some points that need to be clarified. One of these points is the effect of humidity intrusion on AAC members in areas with high relative humidity levels, like Mediterranean climates. Therefore, various tests associated with the mechanical and physical properties of AAC concrete should be carried out, particularly Compressive Strength test in order to assess the strength of AAC blocks. The current project intends to analyse the physical and mechanical properties of autoclaved aerated concrete blocks at three different curing conditions using an accelerated curing tank to compare the effects of curing on the properties of AAC

Структурно-механические свойства гидродинамически активированной древесной массы в аддитивных технологиях

One of the techniques of additive technologies is 3D printing. It is a perspective direction in the development of low-rise housing construction. The process of 3D printing can be performed with various materials. Although this study investigates the possibility of applying hydrodynamically activated wood pulp. A fragmentated wood in the process of activation changes physical and chemical properties because of the cavitation effect. Such fragments in the form of the activated pulp are a solid dispersed system, whose properties depend on humidity. The activated pulp mass is created by moisture elimination, and it can be transported through pipelines. The structure is formed in the process of self-adhesion, without any adhesives, by the appearance of autogenous interactions between the wood particles. The obtained material has a sufficiently high strength and water resistance, which are the prerequisites for the use of activated wood pulp in additive technologies. The 3D printed products are constructed by applying some material in layers at certain time intervals. The main requirements are a steady shape and a homogeneity of the structure. Therefore, the limit of creep rate for the pulp mass was determined that is a yield tensile stress point, above which the material (flow) undergoes an intensive plastic deformation. In this study, a conical plastometer was used according to the method of Academician P.A. Rebinder. The measured parameter depends significantly on the humidity of the pulp. There found an inverse relationship between the humidity and the creep limit. The obtained dependence is fundamental for determination of the thickness of applied layers and the time intervals between applications. The homogeneity of the structure in the interlayer section determines the strength of the entire product. It is obtained when the humidity level is greater than 400 % in the contact area. The high humidity level at the contact area with the low average humidity of the material can be created by microwave radiation treatment. Thus, the moisture is distributed across the thickness of the layer. The treatment also increases the humidity level on the surface and reduces it in the center of the material. For citation: Ermolin V.N., Bayandin M.A., Namyatov A.V., Ostryakova V.A. Structural and Mechanical Properties of Hydrodynamically Activated Wood Pulp in Additive Technologies. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 121–131. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-121-131

A paper-based sensor capable of differentiating ammonia and carbon dioxide gas

Selective and rapid detection of ammonia gas over a wide concentration range is of great importance in many applications such as medical diagnostics and assessing perishable food quality and safety. One of the major obstacles in detection of ammonia is the selectivity and inhibiting the effect of other interfering gases such as carbon dioxide. In this work, we present a polystyrene sulfonate (PSS) coated paper-based sensor as an efficient multi-functional system for detection and differentiation of ammonia from carbon dioxide at high humidity levels ( > 85%) with distinctive resistivity behaviour. This sensor’s resistivity increases in the presence of CO2 and decreases drastically in the presence of NH3 gas, due to interaction with the PSS functional group. The sensor can selectively measure ammonia in the presence of other volatile organic compounds/gases. A linear correlation is observed between resistance and ammonia concentration with a broad range of detection from 0.25 ppm to 2500 ppm. This is remarkably superior to other commercially available sensor with a narrow range of detection from 1 ppm to 100 ppm. In addition, the sensor can monitor meat spoilage in real time at different temperatures (23 ℃ and 4 ℃). Therefore, this disposable paper-based polystyrene sulfonate sensor has high potential for developing a low-cost and portable device for medical diagnostics and determining perishable food quality and safety.

Metal Oxide Nanoparticles Containing Clotrimazole to Suppress Photodegradation of Poly(Vinyl Chloride) Thin Films.

Pol(vinyl chloride) or PVC has functional properties that enable its use in many industrial applications. It suffers from aging, however, in harsh conditions (e.g., elevated temperature or high humidity levels) if oxygen is present. One way to enhance the photostability of PVC is to blend it with additives. Thus, thin films were made by mixing PVC with clotrimazole, and five metal oxide (titanium, copper, cobalt, chromium, and nickel oxides) additives. The metal oxides and clotrimazole were added at concentrations of 0.1 and 0.5% by weight, respectively. The effect of the metal oxide nanoparticles accompanied by clotrimazole on the photodegradation of PVC was then assessed. The results indicated that the additives have a stabilizing effect and protect PVC against photodegradation significantly. The formation of polymeric fragments of small molecular weight containing carbon-carbon double bonds and carbonyl groups was lower in the blends containing metal oxide nanoparticles and clotrimazole than in unblended PVC. Similarly, the decrease in weight was much less for the films blended with additives. Additionally, surface analysis of the irradiated polymeric films showed significantly lower damage in the materials containing additives. The most effective additive in the stabilization of PVC was nickel oxide nanoparticles. The metal oxides are highly alkaline and act as scavengers for the hydrogen chloride produced during the photodegradation of PVC. They additionally act as peroxide decomposers. In contrast, clotrimazole can absorb harmful radiation and act as an ultraviolet absorber due to its heteroatom and aromatic content. Thus, the use of a combination of metal oxide nanoparticles and clotrimazole led to significant improvement in the resistance of PVC toward photodegradation.

Multiplexed DNA-functionalized graphene sensor with artificial intelligence-based discrimination performance for analyzing chemical vapor compositions

This study presents a new technology that can detect and discriminate individual chemical vapors to determine the chemical vapor composition of mixed chemical composition in situ based on a multiplexed DNA-functionalized graphene (MDFG) nanoelectrode without the need to condense the original vapor or target dilution. To the best of our knowledge, our artificial intelligence (AI)-operated arrayed electrodes were capable of identifying the compositions of mixed chemical gases with a mixed ratio in the early stage. This innovative technology comprised an optimized combination of nanodeposited arrayed electrodes and artificial intelligence techniques with advanced sensing capabilities that could operate within biological limits, resulting in the verification of mixed vapor chemical components. Highly selective sensors that are tolerant to high humidity levels provide a target for “breath chemovapor fingerprinting” for the early diagnosis of diseases. The feature selection analysis achieved recognition rates of 99% and above under low-humidity conditions and 98% and above under humid conditions for mixed chemical compositions. The 1D convolutional neural network analysis performed better, discriminating the compositional state of chemical vapor under low- and high-humidity conditions almost perfectly. This study provides a basis for the use of a multiplexed DNA-functionalized graphene gas sensor array and artificial intelligence-based discrimination of chemical vapor compositions in breath analysis applications.

Acoustic activity of bats at power lines correlates with relative humidity: a potential role for corona discharges.

With the ever-increasing dependency on electric power, electrical grid networks are expanding worldwide. Bats exhibit a wide diversity of foraging and flight behaviours, and their sensitivity to anthropogenic stressors suggests this group is very likely to be affected by power lines in a myriad of ways. Yet the effects of power lines on bats remains unknown. Here we assessed the responses of insectivorous bats to very high voltage power lines (VHVPL; greater than 220 kV). We implemented a paired sampling design and monitored bats acoustically at 25 pairs, one pair consisting of one forest edge near to VHVPL matched with one control forest edge. Relative humidity mediates the effects of power lines on bats: we detected bat attraction to VHVPL at high relative humidity levels and avoidance of VHVPL by bats at low relative humidity levels. We argue that the former could be explained by insect attraction to the light emitted by VHVPL owing to corona discharges while the latter may be owing to the physical presence of pylons/cables at foraging height and/or because of electromagnetic fields. Our work highlights the response of bats to power lines at foraging habitats, providing new insight into the interactions between power lines and biodiversity.

Does the multi-proxy Eemian record from the Słup site (central Poland) indicate a more humid climate at the beginning of the hornbeam phase?

A new site of Eemian organogenic deposits in S3up (central Poland) has revealed an intermittent record of several phases within this interglacial. Pollen based studies of the core S3-19, drilled at the littoral zone of the palaeolake, indicated the absence of the E2, E3, E6 and an incomplete record of the E4 and E5 zones of the typical pollen succession. Results of other proxies (plant macrofossils, Cladocera, molluscs, NPPs, isotopes) supported the conclusions derived from the pollen diagram regarding the high humidity and lake water level during the E4 (Corylus-Quercus-Tilia) phase and at the beginning of the E5 (Carpinus-Corylus-Alnus) phase, when the fossil lake was most extensive. Thus, the lack of a record of the E3 and E4 RPAZs was associated with water level lowering and a less humid climate. The results stand in agreement with several other Eemian records from central Poland.

Microclimate analysis of high-density urban residential open enclosures: A case of Thane, India

Urban heat island produces a significant impact by modifying the microclimate in urban areas. To ensure good quality of life with a safe and healthy built environment, the floor space index (FSI) can be an effective tool. It helps to control the urban densities and shape the morphology of the built environment. Taking the case of typical residential development in a densely populated Indian city, an attempt has been made to explore the relationship between FSI and the microclimate of such open spaces that perform like an open enclosure (OE). Adopting the simulation pathway in ENVI-met, a mathematical relationship is established between an important tool used by urban planners and the variables of the microclimate in a typical urban enclosure. The observations indicate that FSI has a strong negative correlation with air temperature and mean radiant temperature. Evaluation of physiological equivalent temperature reveals a similar relationship with FSI, demonstrating a temporal transposition of the trend for a particular FSI range of 2.5-3.5 in the late evening and early morning hours due to high humidity levels and reduced wind speeds. The study will help the planners to prognosticate the microclimatic variables while working out the data-based, logical and well-evaluated future development control regulations.

Seasonal Field Calibration of Low-Cost PM2.5 Sensors in Different Locations with Different Sources in Thailand

Low-cost sensors (LCS) have been increasingly deployed to monitor PM2.5 concentrations. More than 1500 LCS have been installed in Thailand to increase public awareness of air quality. However, performance of these sensors has not been systematically investigated. In this study, PM2.5 LCS were co-located next to a PM2.5 federal equivalent method (FEM) reference instrument at three Thai locations—in the north, center and northeast. We evaluated the performance of a PM2.5 LCS (PMS7003, Plantower) to understand the key factors affecting performance, including emission sources, relative humidity, temperature and PM2.5 concentration. Low PM concentration and high humidity levels had a significant impact on performance. Sensors in a high traffic emission area showed low correlation. The unadjusted PM2.5 LCS performance varied with locations. Errors were mainly observed at low concentrations. They significantly underestimated concentrations in congested urban environments. After calibration, accuracy was improved with multiple regression models. The performance of sensors only at Chiang Mai (CM) during the dry season and Ubon Ratchathani (URT) during the dry and wet seasons were acceptable with coefficient of variation: 5.8 ± 4.7–6.8 ± 5.0%, slope: 0.829–0.945, intercept: 1.12–5.49 µg/m3, R2: 0.880–0.934 and RMSE: 4.3–5.1 µg/m3. In the congested area in Bangkok (BKK), they underestimated concentrations of small particles.

Calculations of adsorption-dependent refractive indices of metal-organic frameworks for gas sensing applications.

Detection of volatile organic compounds (VOCs) is one of the most challenging tasks in modelling breath analyzers because of their low concentrations (parts-per-billion (ppb) to parts-per-million (ppm)) in breath and the high humidity levels in exhaled breaths. The refractive index is one of the crucial optical properties of metal-organic frameworks (MOFs), which is changeable via the variation of gas species and concentrations that can be utilized as gas detectors. Herein, for the first time, we used Lorentz-Lorentz, Maxwell-Ga, and Bruggeman effective medium approximation (EMA) equations to compute the percentage change in the index of refraction (Δn%) of ZIF-7, ZIF-8, ZIF-90, MIL-101(Cr) and HKUST-1 upon exposure to ethanol at various partial pressures. We also determined the enhancement factors of the mentioned MOFs to assess the storage capability of MOFs and the biosensors' selectivity through guest-host interactions, especially, at low guest concentrations.