Search results for "Relative Humidity"

Study of water adsorption and capillary bridge formation for SiO(2) nanoparticle layers by means of a combined in situ FT-IR reflection spectroscopy …

2014

Water adsorption and capillary bridge formation within a layer of SiO2-nanoparticles were studied in situ by means of a combination of quartz crystal microbalance (QCM-D) with dissipation analysis and Fourier transformation infrared reflection absorption spectroscopy (FT-IRRAS). FT-IR data were employed to distinguish the “ice-like” and “liquid-like” contributions and to support the analysis of the QCM-D data concerning mass change and dissipation. Combined measurements show that for SiO2-nanoparticles with a diameter of about 250 nm, the formation of two adsorbed monolayers of water as well as bulk water leads to a rather linear increase in the dissipation for relative humidity values of u…

A correlation linking the predicted mean vote and the mean thermal vote based on an investigation on the human thermal comfort in short-haul domestic…

2015

Abstract The results of an experimental investigation on the human thermal comfort inside the cabin of some Airbus A319 aircrafts during 14 short-haul domestic flights, linking various Italian cities, are presented and used to define a correlation among the predicted mean vote (PMV), a procedure which is commonly used to assess the thermal comfort in inhabited environments, and the equivalent temperature and mean thermal vote (MTV), which are the parameters suggested by the European Standard EN ISO 14505-2 for the evaluation of the thermal environment in vehicles. The measurements of the radiant temperature, air temperature and relative humidity during flights were performed. The air temper…

Effects on Heat Stress of a Flame-Retardant Ensemble for Aluminum Smelters

2000

A common belief is that a flame-retardant clothing ensemble will increase the level of heat stress over ordinary cotton work clothes. This is supported by bench tests on fabrics that indicate higher insulation and vapor resistance values for flame-retardant clothing. This research compared a flame-retardant clothing ensemble for an aluminum smelter (Zirpo wool shirt and FR8 denim pants) with typical cotton work clothing. Four young men walked on a treadmill at two work levels inside a climatic chamber under controlled conditions of heat stress. During each test, heart rate, core temperature, and skin temperatures were continuously monitored and recorded every 5 min. After a physiological st…

Beyond Biodegradability of Poly(lactic acid): Physical and Chemical Stability in Humid Environments

2017

International audience; Poly(lactic acid) (PLA) is the most traded biodegradable and biobased material. It is largely used as ecofriendly substitute of conventional plastics. Nevertheless, one of the main limiting factors is its water sensitivity. PLA reacts with water and is hydrolyzed during time, which determines its performance. Limited information related to the hydrolysis mechanism driven by water in vapor state is available in scientific literature. Literature is mainly focused on the effects of water in liquid state. This lack of information is of significant importance, since PLA interacts with water in both phases. This work was aimed to give a full depiction of the chemical and p…

New trials in the consolidation of waterlogged archaeological wood with different acetone-carried products

2011

Some acetone-carried consolidants for waterlogged archaeological wood were tested in order to evaluate treatments able to save time and energy. In details, colophony (rosin), two esterified colophonies (Rosin 100® and Rosin 459®), a mixture of colophony with PEG 3400 and a vinyl acetate - vinyl versate copolymer (Vinavil 8020S®) were tested. The treatments were carried out at temperatures of 20 and 35 °C on waterlogged maritime pine, elm, oak and beech. The materials came from the archaeological Site of the ancient ships of Pisa (Tuscany, Italy) and were dated back to VII cent. BC – II cent. AD. To evaluate the processes, equilibrium moisture content and dimensional stability of treated woo…

Effect of storage conditions (relative humidity, duration, and temperature) on the germination time of Aspergillus carbonarius and Penicillium chryso…

2012

Fungal conidia are disseminated, often in the air, for a certain period of time, prior to contaminating food products. The objective of this study was to examine the effects of the relative humidity, RH (%), time (day), and temperature (°C) during this period of time, called "storage", on the germination time, τ (h), of Aspergillus carbonarius and Penicillium chrysogenum. A Doehlert design was used in the range, 20-100% RH, 2-28 days, and 5-25 °C. As compared to un-stored conidia, the germination time of conidia stored at 60% RH, 15 days, 5 °C was increased by 23 and 28%, for A. carbonarius and P. chrysogenum, respectively. Stored conidia exhibited a minimum τ value at 60% RH, and 100% RH f…

Measurement-based J(NO2) sensitivity in a cloudless atmosphere under low aerosol loading and high solar zenith angle conditions

2000

Abstract The comparison between measured and simulated photodissociation frequencies of NO 2 , J( NO 2 ) , in a cloudless atmosphere in a recent paper by Fruh et al., 2000 (Journal of Geophysical Research 105, 9843–9857) revealed an overestimation of J(NO2) near ground level by model calculations compared with measurements and an underestimation in the upper part of the aerosol layer. A possible reason for the disagreement is the changing sun position during the vertical ascent. To resolve this problem we carried out a sensitivity study varying the solar zenith angle of 74° by 1.4° (which corresponds to the change of sun position during the vertical flight patterns). This results in a consi…

Summertime and wintertime atmospheric processes of secondary aerosol in Beijing

2020

Secondary aerosol constitutes a large fraction of fine particles in urban air of China. However, its formation mechanisms and atmospheric processes remain largely uncertain despite considerable study in recent years. To elucidate the seasonal variations in fine-particle composition and secondary aerosol formation, an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM), combined with other online instruments, was used to characterize the sub-micrometer particulate matter (diameter < 1 µm, PM1) in Beijing during summer and winter 2015. Our results suggest that photochemical oxidation was the major pathway for sulfate formation during summer, whereas aqueou…

Real-time detection of highly oxidized organosulfates and BSOA marker compounds during the F–BEACh 2014 field study

2017

Abstract. The chemical composition of organic aerosols was analyzed using complementary mass spectrometric techniques during a field study in Central Europe in July 2014 (Fichtelgebirge – Biogenic Emission and Aerosol Chemistry, F–BEACh 2014). Aerosols were analyzed in real-time by Aerosol Flowing Atmospheric-Pressure Afterglow Mass Spectrometry (AeroFAPA–MS), Aerosol Mass Spectrometry (AMS), and Chemical Ionization Atmospheric-Pressure interface Time-of-Flight Mass Spectrometry (CI–APiToF–MS). In addition, offline detection of acidic organic compounds was conducted by non-target screening of filter samples using High Resolution Mass Spectrometry (HRMS) in combination with Ultra-High Pressu…

2016

Abstract. Gaseous formaldehyde (HCHO) is an important precursor of OH radicals and a key intermediate molecule in the oxidation of atmospheric volatile organic compounds (VOCs). Budget analyses reveal large discrepancies between modeled and observed HCHO concentrations in the atmosphere. Here, we investigate the interactions of gaseous HCHO with soil surfaces through coated-wall flow tube experiments applying atmospherically relevant HCHO concentrations of  ∼  10 to 40 ppbv. For the determination of uptake coefficients (γ), we provide a Matlab code to account for the diffusion correction under laminar flow conditions. Under dry conditions (relative humidity  =  0 %), an initial γ of (1.1 ± …