Measurement of Gas Adsorption with Jäntti's Method Using Continuously Increasing Pressure

Jäntti et al. published a method to reduce the time necessary for adsorption measurements. They proposed to extrapolate the equilibrium in the stepwise isobaric measurement of adsorption isotherms by measuring at each step three points of the kinetic curve. For that purpose they approximated the kinetic curve by an exponential function which they derived empirically from there measurements. In the present paper we discuss the applicability of the method for adsorption measurements under continuously varying gas pressure.     

On the applicability of Jäntti’s method of shortening sorption measurements

Jäntti published in 1970 a method to obtain equilibrium values at an early stage of gravimetric sorption measurements. In former papers the authors criticised and extended that method. In the present work we discuss problems of its applicability on practical measurements.     

Asymmetric Synthesis of Both Enantiomers of Protected 5‐Hydroxynorvaline by Hetero‐Diels‐Alder Addition of ethyl 2‐Nitrosoacrylate to (R)‐ and (S)‐1‐Phenylbutyl Vinyl Ether

Both enantiomers of protected 5‐hydroxynorvaline were prepared by hetero‐Diels‐Alder addition of ethyl 2‐nitrosoacrylate to readily available (R)‐ and (S)‐1‐phenylbutyl vinyl ether and a further three‐step manipulation. Attempted synthesis of (±)‐vigabatrin from protected (±)‐5‐hydroxynorvaline was unsuccessful.     

The Jäntti approach using a two-layer model

Jäntti introduced a method to calculate the adsorption equilibrium by the measurement of the actual adsorbed amount at three times after a change of the gas pressure. He applied that method for gas/solid systems in which simple adsorption processes occur and for an infinite number of adsorption sites. In the present paper we discuss the case that the number of sites is decreasing with increasing coverage.This revised version was published online in November 2005 with corrections to the Cover Date.     

The influence of building vibrations on weighing

Data are used from three different institutes to indicate the influence of building vibrations on weighing.     

Computer Simulation of Balance Handling

Several decades ago, when working in the field of magnetism, we had to use a balance the sensitivity of which was limited only by Brownian motion. This balance was a very slow one and to calculate the moment of force measured by it we used its equation of motion, T=Jα+kα+Cα, where we measured the values of all the quantities present on the right-hand side of this equation. At the 21st Conference on Vacuum Microbalance Techniques in Dijon, we suggested that, with the help of a computer, this procedure could also be made applicable to the handling of fast balances. The present paper contributes to this topic by presenting a computer simulation of such a fast balance. This revised version was published online in July 2006 with corrections to the Cover Date.     

The relevance of Jäntti's method for the fast measurement of sorption of water vapour

The time necessary for the measurement of gas adsorption on a solid can be substantially reduced by using Jäntti's directions for data interpretation. This procedure already delivers results after measuring only a few values of the adsorbed mass. In earlier papers we introduced a second order adaptation to Jäntti's method to broaden its applicability. In the present paper we apply this second order treatment to the adsorption of water vapour from moistened air. Specially we pay attention to the diffusion delay caused by the boundary layer around the sample.This revised version was published online in November 2005 with corrections to the Cover Date.     

The measurement of magnetic susceptibilities with commercially available milli — Oerstedmeters,II

In the preceeding paper on this subject a method was described which enabled the measurement of magnetic susceptibilities in constant magnetic fields. In the present paper it is demonstrated that the application of an alternating magnetic field instead of a constant field is advantageous. Many environmental disturbances are eliminated, the measurement time is highly reduced and the amplitude of the magnetizing field can be brought back to 60 Oersted at which fields the sensitivity is still a few percent for diamagnetic substances.     

The measurement of magnetic susceptibilities with commercially available milli-oerstedmeters

A method is described which enables the measurement of magnetic susceptibilities using a magnetometer. This implies that the practical disadvantages of balance techniques can be avoided. Application of the method proves to be possible both for para- and diamagnetic substances. As an example the susceptibility of aqueous solutions of various concentrations of NiCl₂ is measured. The results show that the error is less than 2% of the magnetic susceptibility of water.