Detailed analysis of chemical corrosion of ultra-thin wires used in drift chamber detectors

Ultra-thin metallic anode and cathode wires are frequently employed in low-mass gaseous detectors for precision experiments, where the amount of material crossed by charged particles must be minimised. We present here the results of an analysis of the mechanical stress and chemical corrosion effects observed in 40 and 50 μm diameter silver plated aluminum wires mounted within the volume of the MEG II drift chamber, which caused the breakage of about one hundred wires (over a total of ≈ 12000). This analysis is based on the careful inspection of the broken wires by means of optical and electronic microscopes and on a detailed recording of all breaking incidents. We present a simple empirical model which relates the number of broken wires to their exposure time to atmospheric relative humidity and to their mechanical tension, which is necessary for mechanical stability in the presence of electrostatic fields of several kV/cm. Finally we discuss how wire breakages can be avoided or at least strongly reduced by operating in controlled atmosphere during the mounting stages of the wires within the drift chamber and by choosing a 25 % thicker wire diameter, which has very small effects on the detector resolution and efficiency and can be obtained by using a safer fabrication technique.

The triple oxygen isotope composition of phytoliths, a new proxy of atmospheric relative humidity: controls of soil water isotope composition, temperature, CO₂ concentration and relative humidity

Continental atmospheric relative humidity is a major climate parameter whose variability is poorly understood by global climate models. Models' improvement relies on model–data comparisons for past periods. However, there are no truly quantitative indicators of relative humidity for the pre-instrumental period. Previous studies highlighted a quantitative relationship between the triple oxygen isotope composition of phytoliths, particularly the 17O excess of phytoliths, and atmospheric relative humidity. Here, as part of a series of calibrations, we examine the respective controls of soil water isotope composition, temperature, CO2 concentration and relative humidity on phytolith 17O excess. For that purpose, the grass species Festuca arundinacea was grown in growth chambers where these parameters were varying. The setup was designed to control the evolution of the triple oxygen isotope composition of phytoliths and all the water compartments of the soil–plant–atmosphere continuum. Different analytical techniques (cavity ring-down spectroscopy and isotope ratio mass spectrometry) were used to analyze water and silica. An inter-laboratory comparison allowed to strengthen the isotope data matching. Water and phytolith isotope compositions were compared to previous datasets obtained from growth chamber and natural tropical sites. The results show that the δ′18O value of the source water governs the starting point from which the triple oxygen isotope composition of leaf water, phytolith-forming water and phytoliths evolves. However, since the 17O excess varies little in the growth chamber and natural source waters, this has no impact on the strong relative humidity dependency of the 17O excess of phytoliths, demonstrated for the 40 %–80% relative humidity range. This relative humidity dependency is not impacted by changes in air temperature or CO2 concentration either. A relative humidity proxy equation is proposed. Each per meg of change in phytolith 17O excess reflects a change in atmospheric relative humidity of ca. 0.2 %. The ±15 per meg reproducibility on the measurement of phytolith 17O excess corresponds to a ±3.6 % precision on the reconstructed relative humidity. The low sensitivity of phytolith 17O excess to climate parameters other than relative humidity makes it particularly suitable for quantitative reconstructions of continental relative humidity changes in the past.

The triple oxygen isotope composition of phytoliths, a new proxy of atmospheric relative humidity: controls of soil water isotope composition, temperature, CO₂ concentration and relative humidity

Continental atmospheric relative humidity is a major climate parameter whose variability is poorly understood by global climate models. Models’improvement relies on model-data comparisons for past periods. However, there are no truly quantitative indicators of relative humidity for the pre-instrumental period. Previous studies highlighted a quantitative relationship between the triple oxygen isotope composition of phytoliths, and particularly the 17O-excess of phytoliths, and atmospheric relative humidity. Here, as part of a series of calibrations, we examine the respective controls of soil water isotope composition, temperature, CO2 concentration and relative humidity on phytolith 17O-excess. For that purpose, the grass species Festuca arundinacea was grown in growth chambers where these parameters were varying. The setup was designed to control the evolution of the triple oxygen isotope composition of phytoliths and all the water compartments of the soil-plant-atmosphere continuum. Different analytical techniques (cavity ring-down spectroscopy and isotope ratio mass spectrometry) were used to analyse water and silica. An inter-laboratory comparison allowed to strengthen the isotope data matching. Water and phytolith isotope compositions were compared to previous datasets obtained from growth chamber and natural tropical sites. The results show that the δ'18O value of the source water governs the starting point from which the triple oxygen isotope composition of leaf water, phytolith-forming water and phytoliths evolve. However, since the 17O-excess varies little in the growth chamber and natural source waters, this has no impact on the strong relative humidity-dependency of the 17O-excess of phytoliths, demonstrated for the 40–80 % relative humidity range. This relative humidity-dependency is not impacted by changes in air temperature or CO2 concentration either. A relative humidity proxy equation is proposed. Each per meg of change in phytolith 17O-excess reflects a change in atmospheric relative humidity of ca. 0.2 %. The ±15 per meg reproducibility on the measurement of phytolith 17O-excess corresponds to a ± 3.6 % precision on the reconstructed relative humidity. The low sensitivity of phytolith 17O-excess to climate parameters other than relative humidity makes it particularly suitable for quantitative reconstructions of continental relative humidity changes in the past.

The Effect of Humidified Air on Yarn Properties in a Jet-Ring Spinning System

In this study, the effect of 100% atmospheric relative humidity on yarn properties was investigated using jet-ring nozzles and compared with the yarn properties of yarns produced with air operated jet-ring nozzles under normal conditions. As a humidification system, a pneumatic conditioner, also known as a lubricant, was used in pneumatic systems. This conditioner was connected just before the pneumatic distributor that supplies air to the nozzles. The tube in stage 2 of the conditioner was filled with pure water at room temperature (25 °C ± 2 °C). The air conditioner dose was adjusted to 100% atmospheric relative humidity. The use of humidified air to jet-ring nozzles had a slight positive effect on all yarn properties (yarn hairiness, yarn irregularity, yarn elongation and yarn tenacity). According to the results, it resulted in a 1% to 3% improvement in yarn quality. This study is the first example and an original study in this field, as there is no study using humidified air in existing jet-ring air nozzle studies. It was proven in this study that humidified air results in a slight improvement in yarn properties.

Atmospheric Relative Humidity Can Increase the Spread of COVID-19

COVID-19 has been spreading around the world since the end of 2019, and there is no sign of a slowdown. Previous studies on seasonality of similar infectious diseases have hinted that meteorological factors may influence COVID-19 outbreaks as well1. Here we show, based on data collected in 132 cities of China, that relative humidity, as an essential meteorological indicator, is positively correlated with the growth rate of incidence of COVID-19, which contradicts previous research findings. Our result suggests an increasing risk of COVID-19 cases as summer and rain seasons arrive in many places of the world. They also help countries and regions to formulate pandemic prevention and control measures and policies according to local meteorological characteristics.

Impact Assessment of Houseplants on Atmospheric Relative Humidity in the Residential Buildings of Udaipur, Rajasthan

Flora is the nature’s most precious gift to man. In ancient times, regard and love for flora was so great that this kindred relationship was extended even to houseplants. In this study, relative humidity level in the selected rooms, i.e., drawing rooms and dining rooms of the 10 west facing residential buildings along with the National Highway- 8 in polluted zone, of Udaipur Rajasthan was analyzed. Four varieties of foliage and succulent plants were kept in one, two or four suitable corners with four different habits, viz., Opened and Closed windows and fan in ON and OFF mode. To find out the existing relative humidity level, all the experiments were done without any houseplants on day 1 in selected rooms. The houseplants were kept on day 2 to judge the impact of houseplants on humidity level and again houseplants were removed on day 3 to know the retention of impact of houseplants. As a result, it was found that foliage plants were more effective than succulents in maintaining the level of relative humidity of the atmosphere.

Testing the Symmetric Assumption of Complementary Relationship: A Comparison between the Linear and Nonlinear Advection-Aridity Models in a Large Ephemeral Lake

The accuracy of a complementary relationship (CR) evapotranspiration (ET) model depends on how to parameterize the relationship between apparent potential ET and actual ET as the land surface changes from wet to dry. Yet, the validity of its inherent symmetric assumption of the original CR framework, i.e., the B value equal to one, is controversial. In this study, we conduct a comparative study between a linear, symmetric version (B = 1) and a nonlinear, asymmetric version (B is not necessarily equal to 1) of the advection-aridity (AA) CR model in a large ephemeral lake, which experiences dramatic changes in surface/atmosphere humidity. The results show that B was typically 1.1 ± 1.4 when ET ≤ ETPT ≤ ETPM, where ETPM and ETPT are estimated using the Penman (PM) and Priestley–Taylor (PT) equations, respectively; the AA model performed reasonably well in this case. However, the value of B can be negative and deviate from 1 significantly if the inequality ET ≤ ETPT ≤ ETPM is violated, which is quite common in humid environments. Because the actual ET can be negatively (B > 0) or positively (B < 0) related to the evaporative demand of the air, the nonlinear AA model generally performs better than the AA model if ET ≤ ETPM is satisfied. Although B is not significantly correlated with the atmospheric relative humidity (RH), both models, especially the nonlinear AA model, resulted in negative biases when ET > ETPM, which generally occur at high RH conditions. Both the linear and the nonlinear AA models performed better under higher water level conditions, however, our study highlights the need for higher-order (≥3) polynomial functions when CR models are applied in humid environments.