Search results for " solution"

Aqueous Supramolecular Polymers and Hydrogels

2019

GEPOL: An improved description of molecular surfaces. I. Building the spherical surface set

1990

The algorithm used by the program GEPOL to compute the Molecular Surface (MS), as defined by Richards, is presented in detail. GEPOL starts like other algorithms from a set of spheres with van der Waals radii, centered on the atoms or group of atoms of the molecule. GEPOL computes the MS by first searching the spaces inaccessible to the solvent and consequently filling them with a new set of spheres. Here we study the behavior of the method with its parameters, presenting several examples of application.

Study on Interfacial Surface in Modified Spray Tower

2019

This paper presents an analysis of the changes in interfacial surface and the size of droplets formed in a spray tower. The interfacial surface and the size of droplets formed are of fundamental importance to the performance of the equipment, both in terms of pressure drop and process efficiency. Liquid film and droplet sizes were measured using a microphotography technique. The confusors studied were classical, with profiled inside surface, and with double profiled inside surface. The liquids studied were water and aqueous solutions of high-molecular polyacrylamide (PAA) of power-law characteristics. The ranges of process Reynolds number studied were as follows: ReG &isin

Stefan-Boltzmann Radiation on Non-convex Surfaces

1997

We consider the stationary heat equation for a non-convex body with Stefan–Boltzmann radiation condition on the surface. The main virtue of the resulting problem is non-locality of the boundary condition. Moreover, the problem is non-linear and in the general case also non-coercive and non-monotone. We show that the boundary value problem has a maximum principle. Hence, we can prove the existence of a weak solution assuming the existence of upper and lower solutions. In the two dimensional case or when a part of the radiation can escape the system we obtain coercivity and stronger existence result. © 1997 by B.G. Teubner Stuttgart-John Wiley & Sons, Ltd.

On the significance of molecular surfaces and thermodynamic interactions for the excess viscosities of liquid mixtures

1994

The viscosities η of homogeneous binary mixtures of liquids are usually approximated as In η = ϕ1 In η1 + ϕ2 In η2 where ϕi and ηi are the volume fractions and the viscosities, resp., of the i-th pure substance; the behavior of real systems is then discussed in terms of Δ In η, the deviations from the above reference behavior. Here a semi-empirical approach is presented according to which volume fractions are replaced by the surface fractions Ωi to create a more realistic reference state, and the thermodynamic interaction parameter g is taken into account. The new equation reads (expressing it for practical purposes still in the terms of ϕi) γ is a geometric factor, measuring the difference…

Molecular surface calculations on organic compounds

1992

Abstract The molecular surface area was calculated for 82 hydrocarbons, esters, ethers, alcohols and ketones including linear, branched and cyclic ones. The relationship between the aqueous solubility and the molecular surface area was determined for each family of compounds and for all the families together. The results show that solubility is mainly determined by molecular surface area and that the influence of functional group is the same for all the oxygen containing compounds studied.

1991

Preparation des polymeres (CHR-CH 2 SO 2 ) (R=(CH 2 ) 9 N + Me 2 (CH 2 ) 3 SO 3 − , (CH 2 ) 8 CO[NC 4 H 8 N + (Me)([CH 2 ] 3 SO 3 − )] et R=CH 2 OCH 2 CHOHCH 2 N + Me(C 10 H 21 )(CH 2 ) 3 SO 3 − ) par copolymerisation spontanee des sels d'ammonium vinyliques correspondants avec SO 2 dans l'eau. Leurs proprietes de surface et de solubilisation de molecules hydrophobes en solution aqueuse sont caracteristiques de polysavons

Smart Sustainable Cities of the New Millennium: Towards Design for Nature

2021

AbstractUrban environments consist of a mosaic of natural fragments, planned and unintentional habitats hosting both introduced and spontaneous species. The latter group exploits abandoned and degraded urban niches which, in the case of plants, form what is called thethird landscape. In the Anthropocene, cities, open spaces and buildings must be planned and designed considering not only human needs but also those of other living organisms. The scientific approach of habitat sharing is defined asreconciliation ecology, whilst the action of implementing the ecosystem services and functioning of such anthropogenic habitats is calledUrban Rehabilitation. However, urban development still represe…

City logistics – A Strategic Element of Sustainable Urban Development

2016

Abstract The main purpose of this article is to present the basic development trends in the logistics area of the city, some concept of sustainable logistics and innovative technologies prerequisites to its implementation. The author shows such intelligent technologies as e.g. intelligent traffic control, modular containers, which help to improve utilization of vehicle capacity, and alternative means of transport. This will help to reduce the load on the road infrastructure, thus improving the quality of the environment and life in the city. The main trend in sustainable city logistics is cooperation between suppliers, customers and the public administration. Implementation of intelligent l…

In vitro skin penetration of bronidox, bronopol and formaldehyde from cosmetics

2020

The objective was to evaluate the influence of the formulation in the in vitro transdermal absorption through pig ear skin of three preservatives, bronopol, bronidox and formaldehyde as well as the absorption of formaldehyde from bronopol and dimethyloldimethyl hydantoin (DMDM hydantoin). An aqueous solution, an O/W emulsion and a hydrogel were assayed. Bronidox and bronopol absorption depends on the formulation. The O/W emulsion was the system that least promoted absorption of bronidox while the absorption of bronopol was lower from the hydrogel. The aqueous solution provided maximal transdermal absorption of both preservatives. Moreover, the transdermal absorption of formaldehyde released…