Search results for "humid"
showing 10 items of 334 documents
Analysis of Organic Aerosols Using a Micro-Orifice Volatilization Impactor Coupled to an Atmospheric-Pressure Chemical Ionization Mass Spectrometer
2014
We present the development and characterization of a combination of a micro-orifice volatilization impactor (MOVI) and an ion trap mass spectrometer (IT/MS) with an atmospheric-pressure chemical ionization (APCI) source. The MOVI is a multi-jet impactor with 100 nozzles, allowing the collection of aerosol particles by inertial impaction on a deposition plate. The pressure drop behind the nozzles is approximately 5%, resulting in a pressure of 96 kPa on the collection surface for ambient pressures of 101.3 kPa. The cut-point diameter (diameter of 50% collection efficiency) is at 0.13 μm for a sampling flow rate of 10 L min–1. After the collection step, aerosol particles are evaporated by he…
Heterozygote Advantage Probably Maintains Rhesus Factor Blood Group Polymorphism: Ecological Regression Study
2016
Rhesus factor polymorphism has been an evolutionary enigma since its discovery in 1939. Carriers of the rarer allele should be eliminated by selection against Rhesus positive children born to Rhesus negative mothers. Here I used an ecologic regression study to test the hypothesis that Rhesus factor polymorphism is stabilized by heterozygote advantage. The study was performed in 65 countries for which the frequencies of RhD phenotypes and specific disease burden data were available. I performed multiple multivariate covariance analysis with five potential confounding variables: GDP, latitude (distance from the equator), humidity, medical care expenditure per capita and frequencies of smokers…
Investigations on The Micro-Structure of Hardened Cement Pastes
1988
Abstract Creep is a mechanical property, that has to be taken into account in the design of concrete constructions. Earlier studies showed that creep of concrete, among other things, depends on the relative humidity of the environment and on the type of cement used. The origin of creep lies in the hydrated cement paste, which is present between the aggregates. This paper, based on a thesis of H.H. Willems (ref. 1) deals with the relation between the creep behaviour and the microstructure of hardened Portland (PC) and Portland-blastfurnace cement (PBC) pastes. At several relative humidities shrinkage and creep experiments have been performed with thin-walled hollow cylindrical specimens. Nex…
Adhesion and adhesion hysteresis of mica surfaces covered with bola-amphipiles in dry and humid air
1998
Abstract Bola-amphiphiles with spherical hydrophilic chinuclidinium head groups form laterally ordered monolayers on mica by adsorption from solution. To measure the surface adhesion, JKR-type compression/decompression cycles have been performed with the surface forces apparatus (SFA). In an inert atmosphere, the adhesion energy on increasing the contact area is much lower than predicted by wetting experiments. Furthermore, the pronounced adhesion hysteresis varies from sample to sample in a wide range, indicating a defect-rich surface. On increase of the relative humidity (rh), the reproducibility improves and the values for the adhesion energy measured on compression and decompression con…
Enhanced porosity in a new 3D Hofmann-like network exhibiting humidity sensitive cooperative spin transitions at room temperature
2011
The porous coordination polymers (PCPs) of general formula {Fe(bpac)[M(CN)4]}·guest (M = Pt, Pd) exhibit larger channels than previously synthesised 3D-Hofmann-like PCP. The channels are partially occupied by uncoordinated guest bpac ligands and labile H2O molecules. These PCPs exhibit very scarce cooperative spin crossover behaviour around room temperature with a large hysteresis loop (up to 49 K) and also display sensitivity to humidity and guest molecules. The inclusion of bpac molecules in the 3D network can be avoided by adding competitive volatile molecules during the crystallization process, affording the guest-free material. The spin crossover behavior of different guest and guest-f…
New aspects of scattering and absorbing properties of atmospheric aerosol particles
1972
Abstract Knowledge of the scattering and absorbing processes of the atmospheric aerosol particles in the solar wavelength range is necessary in order to calculate the energy balance of the atmosphere. Both of these depend on the relative humidity of the air. Until now little was known of the behavior of the particles. This paper shows experimental and theoretical results of the real and imaginary part of the refractive index of the aerosol particles at different relative humidities.
Effect of modified starch or maltodextrin incorporation on the barrier and mechanical properties, moisture sensitivity and appearance of soy protein …
2012
Abstract This work aimed to study the effect of starch (acetylated di-starch phosphate and starch acetate) and maltodextrin (DE 10.2 and DE 15.6) on the properties of soy protein isolate (SPI) films. Films were cast from heated (70 °C for 20 min) alkaline (pH 10) aqueous solutions of soy protein isolate (8%) containing glycerol (50% of SPI) as a plasticizer and starch or maltodextrin (20% of SPI). For all types of films, water vapor sorption kinetics during 24 h at 25 °C and 75% relative humidity (RH), diffusion coefficient of water vapor, water vapor permeability at 25 °C for two relative humidity differentials (40–75 and 40–100%), tensile strength and elongation at break, color and micros…
New insights on the thermal analysis of low moisture composite foods.
2014
Abstract Low moisture baked products were investigated with a view to characterising the effect of both formulation and humidity on their physical stability. At the end of the baking process, the samples were in the amorphous state as a result of starch gelatinization and sugar melting. Their thermal properties were analyzed with differential scanning calorimetry and their glass transitions were studied. The DSC thermograms were thoroughly studied through a Gaussian deconvolution of the first derivative of their heat flow. This approach evidenced a multiple phase behavior with different glass transitions in composite systems. They were associated with either a polymer-rich phase and/or a pl…
Effect of environmental humidity and coating on aroma transfer through treated papers
2012
Abstract Coupled transfers of aroma compounds and water vapour were investigated by varying the relative humidity gradient of storage (50% or 90%) of two paper packaging at 25 °C. These papers differed in their coating surface: both were identically impregnated then supercalendered, and only one was twice coated on both sides with a synthetic barrier substance. Permeability and solubility coefficients were determined. The coating treatment was more effective to decrease the permeabilities of water vapour and ethyl ester than the effect of RH. On the contrary, the RH modified the water content of the treated papers and affected more strongly their permeability and solubility to cis-3-hexenol…
Humidity Sensing by Polymer-Loaded UHF RFID Antennas
2012
Passive ultra high-frequency radio frequency identification tags, besides item labeling, are also able to exploit capability to sense the physical state of the tagged object as well as of the surrounding environment. Here, a new family of polymer-doped tags are proposed and fully characterized for the detection of ambient humidity. A sensitive chemical species based on PEDOT:PSS is used to load a shaped slot, carved into a folded-like patch tag. The communication and sensing capabilities of the resulting radio-sensor are investigated by means of simulation and measurements that show how to control and balance above opposite requirements by a proper deposition of the sensitive material. The …