The Permeability of Rubber to Water Vapor

1943 ◽  
Vol 16 (2) ◽  
pp. 388-399 ◽  
Author(s):  
J. W. Van Dalfsen
Keyword(s):  
Water Vapor ◽  
Internal Structure ◽  
High Accuracy ◽  
Latex Films ◽  
Simple Method ◽  
Latex Particles ◽  
Methods Of Determination ◽  
Vulcanized Rubber ◽  
Series Of Experiments ◽  
Structure Of Matter

Abstract In connection with a study of various kinds of vulcanized rubber, including rubber films from vulcanized latex and latex films vulcanized in the dry state, it seemed desirable to investigate the packing of the latex particles. To what extent, for example, are these still present or are they coalesced? It is known that the diffusion of water vapor through solid substances may give an indication of the internal structure of matter. With this in mind, a search was made for a simple method to determine the diffusion of water vapor through rubber; high accuracy was not required so much as were simplicity and adaptability to a long series of experiments. Such a procedure was found in the method described by Hoekstra for determining the permeability of varnish films to water vapor. A detailed description of the method is given later in this paper. More accurate methods of determination, applied to rubber, have previously been described by others, but these procedures are less suitable for systematic tests.

Two months of measurements with an autonomous thermodynamic Raman lidar in Lindenberg

2021 ◽  
Author(s):  
Diego Lange Vega ◽  
Andreas Behrendt ◽  
Volker Wulfmeyer
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Inversion Layer ◽  
Measurement Range ◽  
High Accuracy ◽  
Free Troposphere ◽  
Raman Lidar ◽  
Backscatter Coefficient ◽  
Geophysical Research ◽  
Turbulence Scale

<p>Between 15 July 2020 and 19 September 2021, the Atmospheric Raman Temperature and Humidity Sounder (ARTHUS) collected data at the Lindenberg Observatory of the Deutscher Wetterdienst (DWD), including temperature and water vapor mixing ratio with a high temporal and range resolution.</p> <p>During the operation period, very stable 24/7 operation was achieved, and ARTHUS demonstrated that is capable to observe the atmospheric boundary layer and lower free troposphere during both daytime and nighttime up to the turbulence scale, with high accuracy and precision, and very short latency. During nighttime, the measurement range increases even up to the tropopause and lower stratosphere.</p> <p>ARTHUS measurements resolve the strength of the inversion layer at the planetary boundary layer top, elevated lids in the free troposphere, and turbulent fluctuations in water vapor and temperature, simultaneously (Lange et al., 2019, Wulfmeyer et al., 2015). In addition to thermodynamic variables, ARTHUS provides also independent profiles of the particle backscatter coefficient and the particle extinction coefficient from the rotational Raman signals at 355 nm with much better resolution than a conventional vibrational Raman lidar.</p> <p>At the conference, highlights of the measurements will be presented. Furthermore, the statistics of more than 150 comparisons with local radiosondes will be presented which confirm the high accuracy of the temperature and moisture measurements of ARTHUS.</p> <p><strong><em>Acknowledgements</em></strong></p> <p>The development of ARTHUS was supported by the Helmholtz Association of German Research Centers within the project Modular Observation Solutions for Earth Systems (MOSES). The measurements in Lindenberg were funded by DWD.</p> <p><strong><em>References </em></strong></p> <p>Lange, D., Behrendt, A., and Wulfmeyer, V. (2019). Compact operational tropospheric water vapor and temperature Raman lidar with turbulence resolution. <em>Geophysical Research Letters</em>, 46. https://doi.org/10.1029/2019GL085774</p> <p>Wulfmeyer, V., R. M. Hardesty, D. D. Turner, A. Behrendt, M. P. Cadeddu, P. Di Girolamo, P. Schlüssel, J. Van Baelen, and F. Zus (2015), A review of the remote sensing of lower tropospheric thermodynamic profiles and its indispensable role for the understanding and the simulation of water and energy cycles, <em>Rev. Geophys.</em>, 53,819–895, doi:10.1002/2014RG000476</p>

scholarly journals l-Arginine Grafted Poly(Glycerol Sebacate) Materials: An Antimicrobial Material for Wound Dressing

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1457 ◽  
Author(s):  
Chia-Chun Wang ◽  
Ting-Yu Shih ◽  
Yi-Ting Hsieh ◽  
Jie-Len Huang ◽  
Jane Wang
Keyword(s):  
Water Vapor ◽  
Wound Dressing ◽  
Transmission Rate ◽  
Water Vapor Transmission Rate ◽  
Grafting Ratio ◽  
Chemical Conjugation ◽  
Water Vapor Transmission ◽  
Antimicrobial Material ◽  
Series Of Experiments ◽  
And Staphylococcus Aureus

This study focuses on the development and evaluation of a novel wound dressing material. l-arginine grafted poly(glycerol sebacate) materials (PGS-g-Arg) are developed by chemical conjugation of l-arginine on poly(glycerol sebacate) chains and the mechanical property, water vapor transmission rate, antimicrobial functions and biocompatibility are investigated. At various l-arginine grafting ratio, the mechanical properties are tunable. It was found that between 7–13% l-arginine grafting ratios, the tensile strengths of PGS-g-Arg were similar to that of natural skin. These materials are shown with a low water vapor transmission rate, 6.1 to 10.3 g/m2/h, which may form a barrier and assist in the closure of wounds. Inhibition in the growth of Pseudomonas aeruginosa and Staphylococcus aureus was observed on PGS-g-Arg, and a series of experiments were conducted to confirm its biocompatibility. In summary, l -arginine grafted poly(glycerol sebacate) may offer a novel option for wound dressing.

THE SORPTION OF VAPORS BY ACTIVE SILICA

1935 ◽  
Vol 12 (1) ◽  
pp. 41-56 ◽  
Author(s):  
L. M. Pidgeon
Keyword(s):  
Water Vapor ◽  
Silica Gel ◽  
Dynamic Method ◽  
Activated Alumina ◽  
Simple Method ◽  
Commercial Alumina ◽  
Method Of Production ◽  
Effective Sorbent ◽  
Better Than

The sorptive properties of a new active silica have been examined. This sorbent is prepared by the action of acids on the mineral serpentine. The quartz spiral sorption balance has been employed to obtain isotherms for water, benzene and alcohol. Relative rates of sorption have been measured and compared with those for silica gel.Efficiency measurements have also been made, using the dynamic method, with water vapor as the sorbate. Comparative measurements have been carried out on commercial silica gel, and data are cited from the literature for activated alumina. A comparison of the data indicates that active silica is inferior to silica gel but somewhat better than commercial alumina. Its simple method of production combined with reasonably good sorptive properties should result in a cheap and effective sorbent for technical purposes.The type of isotherm exhibited by active silica is similar to that associated with the "chalky" gels described by Holmes. Certain theoretical aspects of sorption by "chalky" and "vitreous" gels are discussed.

scholarly journals A Simple Method For Determining Optimum Corrections For High-Accuracy Epma In Difficult Chemical Systems

2002 ◽  
Vol 8 (S02) ◽  
pp. 438-439
Author(s):  
J. T. Armstrong ◽  
R. B. Marinenko ◽  
J. M. Davis
Keyword(s):  
High Accuracy ◽  
Simple Method ◽  
Chemical Systems

scholarly journals Satellite mapping of PM<sub>2.5</sub> episodes in the wintertime San Joaquin Valley: a “static” model using column water vapor

2020 ◽  
Vol 20 (7) ◽  
pp. 4379-4397 ◽  
Author(s):  
Robert B. Chatfield ◽  
Meytar Sorek-Hamer ◽  
Robert F. Esswein ◽  
Alexei Lyapustin
Keyword(s):  
Water Vapor ◽  
Mixed Layer ◽  
Atmospheric Correction ◽  
Vertical Mixing ◽  
San Joaquin Valley ◽  
Winter Period ◽  
Statistical Regression ◽  
Simple Method ◽  
Near Surface

Abstract. The use of satellite aerosol optical thickness (AOT) from imaging spectrometers has been successful in quantifying and mapping high-PM2.5 (particulate matter with a mass <2.5 µm diameter) episodes for pollution abatement and health studies. However, some regions have high PM2.5 but poor estimation success. The challenges in using AOT from imaging spectrometers to characterize PM2.5 worldwide was especially evident in the wintertime San Joaquin Valley (SJV). The SJV's attendant difficulties of high-albedo surfaces and very shallow, variable vertical mixing also occur in other significantly polluted regions around the world. We report on more accurate PM2.5 maps (where cloudiness permits) for the whole winter period in the SJV (19 November 2012–18 February 2013). Intensive measurements by including NASA aircraft were made for several weeks in that winter, the DISCOVER-AQ (Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality) California mission. We found success with a relatively simple method based on calibration and checking with surface monitors and a characterization of vertical mixing, and incorporating specific understanding of the region's climatology. We estimate PM2.5 to within ∼7 µg m−3 root mean square error (RMSE) and with R values of ∼0.9, based on remotely sensed multi-angle implementation of atmospheric correction (MAIAC) observations, and certain further work will improve that accuracy. Mapping is at 1 km resolution. This allows a time sequence of mapped aerosols at 1 km for cloud-free days. We describe our technique as a “static estimation.” Estimation procedures like this one, not dependent on well-mapped source strengths or on transport error, should help full source-driven simulations by deconstructing processes. They also provide a rapid method to create a long-term climatology. Essential features of the technique are (a) daily calibration of the AOT to PM2.5 using available surface monitors, and (b) characterization of mixed layer dilution using column water vapor (CWV, otherwise “precipitable water”). We noted that on multi-day timescales both water vapor and particles share near-surface sources and both fall to very low values with altitude; indeed, both are largely removed by precipitation. The existence of layers of H2O or aerosol not within the mixed layer adds complexity, but mixed-effects statistical regression captures essential proportionality of PM2.5 and the ratio variable (AOT ∕ CWV). Accuracy is much higher than previous statistical models and can be extended to the whole Aqua satellite data record. The maps and time series we show suggest a repeated pattern for large valleys like the SJV – progressive stabilization of the mixing height after frontal passages: PM2.5 is somewhat more determined by day-by-day changes in mixing than it is by the progressive accumulation of pollutants (revealed as increasing AOT).

A rapid and simple method to assess the changes of human VEGF mRNA based on dual molecular beacons

2014 ◽  
Vol 6 (13) ◽  
pp. 4585-4592 ◽  
Author(s):  
Bin Liu ◽  
Wei Wang ◽  
Chen Li ◽  
Chunyi Tong ◽  
Ying Long
Keyword(s):  
High Accuracy ◽  
Fluorescence Method ◽  
Molecular Beacons ◽  
Vegf Mrna ◽  
Simple Method

A fluorescence method with wide promising applications was developed for VEGF mRNA assay with high accuracy and specificity by applying dual molecular beacons as probes.

Mechanical Stability Test for Hevea Latex

1950 ◽  
Vol 23 (4) ◽  
pp. 981-994
Author(s):  
H. G. Dawson
Keyword(s):  
High Speed ◽  
Colloidal Stability ◽  
Mechanical Stability ◽  
Stability Test ◽  
Simple Method ◽  
Latex Particles ◽  
Interfacial Film ◽  
Total Solids ◽  
Stability Time

Abstract The mechanical stability test is a rapid, simple method of estimating the colloidal stability or quality of Hevea latex by high-speed stirring. Latex particles start to agglomerate as soon as the peripheral speed of the agitator reaches a certain minimum value. Progressive flocculation continues until mechanical coagulation occurs. The end point is defined as the time in seconds required to coagulate 0.5 to 1.0 per cent of the total solids. If the shear is constant, the time is proportional to the colloidal stability, which depends upon the interfacial film between the latex particles and the serum. The mechanical stability time depends critically on the size, the total solids, and the temperature of sample.

scholarly journals High-accuracy measurements of total column water vapor from the Orbiting Carbon Observatory-2

2016 ◽  
Vol 43 (23) ◽  
pp. 12,261-12,269 ◽  
Author(s):  
Robert R. Nelson ◽  
David Crisp ◽  
Lesley E. Ott ◽  
Christopher W. O'Dell
Keyword(s):  
Water Vapor ◽  
High Accuracy ◽  
Total Column
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