Poly(N-isopropylacrylamide): experiment, theory and application

Temperature-sensitive aqueous microgels.

Jets, ie collimated streams of matter, occur from the microscale up to the large-scale structure of the universe Our focus will be mostly on surface tension effects, which result from the cohesive properties of liquids Paradoxically, cohesive forces promote the breakup of jets, widely encountered in nature, technology and basic science, for example in nuclear fission, DNA sampling, medical diagnostics, sprays, agricultural irrigation and jet engine technology Liquid jets thus serve as a paradigm for free-surface motion, hydrodynamic instability and singularity formation leading to drop breakup In addition to their practical usefulness, jets are an ideal probe for liquid properties, such as surface tension, viscosity or non-Newtonian rheology They also arise from the last but one topology change of liquid masses bursting into sprays Jet dynamics are sensitive to the turbulent or thermal excitation of the fluid, as well as to the surrounding gas or fluid medium The aim of this review is to provide a unified description of the fundamental and the technological aspects of these subjects

Physics of liquid jets

Polymers have played an integral role in the advancement of drug delivery technology by providing controlled release of therapeutic agents in constant doses over long periods, cyclic dosage, and tunable release of both hydrophilic and hydrophobic drugs. From early beginnings using off-the-shelf materials, the field has grown tremendously, driven in part by the innovations of chemical engineers. Modern advances in drug delivery are now predicated upon the rational design of polymers tailored for specific cargo and engineered to exert distinct biological functions. In this review, we highlight the fundamental drug delivery systems and their mathematical foundations and discuss the physiological barriers to drug delivery. We review the origins and applications of stimuli-responsive polymer systems and polymer therapeutics such as polymer-protein and polymer-drug conjugates. The latest developments in polymers capable of molecular recognition or directing intracellular delivery are surveyed to illustrate areas of research advancing the frontiers of drug delivery.

Polymers for Drug Delivery Systems

Interest in thermoresponsive polymers has steadily grown over many decades, and a great deal of work has been dedicated to developing temperature sensitive macromolecules that can be crafted into new smart materials. However, the overwhelming majority of previously reported temperature-responsive polymers are based on poly(N-isopropylacrylamide) (PNIPAM), despite the fact that a wide range of other thermoresponsive polymers have demonstrated similar promise for the preparation of adaptive materials. Herein, we aim to highlight recent results that involve thermoresponsive systems that have not yet been as fully considered. Many of these (co)polymers represent clear opportunities for advancements in emerging biomedical and materials fields due to their increased biocompatibility and tuneable response. By highlighting recent examples of newly developed thermoresponsive polymer systems, we hope to promote the development of new generations of smart materials.

New directions in thermoresponsive polymers.

PURPOSE: To economically obtain ethanol of high purity without containing high- and low- boiling impurities, by distilling a specific ethanol extract gas directly under supercritical conditions to remove high-boiling impurities, subjecting the resultant vapor phase to gas-liquid separation and removing CO 2 , etc. CONSTITUTION: A raw material aqueous solution of ethanol is injected into a boundary part of an enriching section (1a) and stripping section (1b) of the first extraction column 1 set at about 40°C under about 150atm, and supercritical gas (C), e.g. CO 2 , in the supercritical state is blown from the column bottom part and brought into countercurrent contact therewith under isothermal and isobaric conditions to give an ethanol extract gas (G 1 ) from the column top. The resultant ethanol extract gas (G 1 ) is then introduced into the second extraction column 2 under the same high pressure as the first extraction column 1 and distilled while heating to take out a low-boiling component consisting of low-boiling impurities, supercritical gas, etc., from the column top as an extraction fluid (G 2 ). On the other hand, a high-boiling component is taken out of the column top as an extraction fluid (G 2 ) and a high-boiling component is taken out of the column bottom part as a high-boiling impurity (L 1 ) and released to the outside of the system. The above-mentioned fluid (G 2 ) is decompressed to about 50atm, led to the first CO 2 recovery column 3 and subjected to gas-liquid separation. The resultant vapor phase (G 3 ) as a solvent is circulated for use, and the liquid phase (L 2 ) is partially decompressed to ordinary pressure, led to the second CO 2 recovery column 4 and subjected to gas-liquid separation. The liquid phase part (L 3 ) is recovered as a product and the vapor phase part (G 4 ) as a solvent is compressed and circulated for use. COPYRIGHT: (C)1987,JPO&Japio

Purification of ethanol

The limit-deposit velocity at which a solid deposit begins to build up in the bottom of a pipe is numerically analyzed on the basis of a two-dimensional flow model and a comparison is made with experimental results. The model explains well the fact that the limit-deposit velocity increases with an increase in the delivered concentration of solids, and after reaching a maximum at a certain concentration it decreases gradually at higher concentrations. It is shown that, at lower solid concentrations, the shear stress acting on the surface of the bed of particles is the dominant factor for transporting the solids, while at higher concentrations the drag force of fluid within the bed plays a very important role.

Simulation of limit-deposit velocity in horizontal liquid-solid flow

New equation of state based on the significant structure model

The Scatchard-Hildebrand theory of regular solutions was modified by introducing the excess entropy of mixing term and by using temperature dependent solubility parameters. A comparison was made of the present treatment with the data available in the literature and the experimental results concerning the n-hexane-benzene-toluene and n-hexane-benzene-monochlorobenzene systems. The modified theory was shown, from the knowledge of pure components only, to be capable of predicting vapor -liquid equilibria for systems not containing polar components and useful for screening solvents effective for extractive distillation.

Prediction of solvent selectivity in extractive distillation and of vapor-liquid equilibria of hydrocarbons

For the separation of fusel oil from low-concentration fermentation broths, ternary liquid-liquid equilibria at 323.2 K were measured for the systems of water and 1, 1-difluoroethane with alcohols (l-propanol, 1-butanol and 1-pentanol). The liquefied gas 1, 1-difluoroethane can achieve much higher distribution coefficients of l-propanol, 1-butanol and 1-pentanol than ethanol. Therefore, 1-propanol, 1-butanol and 1-pentanol will be selectively removed from low-concentration ethanol aqueous solutions with liquefied 1, 1-difluoroethane at low solvent ratios. The liquid-liquid equilibrium data were correlated by the UNIQUAC and NRTL equations. The UNIQUAC equation gave better correlation of the experimental data than did the NRTL equation. However, the two-phase regions estimated by the UNIQUAC equation were larger than the experimental results for the systems of water + 1-propanol + 1, 1-difluoroethane and water + 1-pentanol + 1, 1-difluoroethane.

https://www.jstage.jst.go.jp/article/jcej1968/21/2/21_2_129/_pdf

High-pressure ternary liquid-liquid equilibria for the systems of water, alcohol (1-propanol, 1-butanol and 1-pentanol) and 1, 1-difluoroethane at 323.2 k

Shozaburo Saito

Papers

Purification of ethanol

Simulation of limit-deposit velocity in horizontal liquid-solid flow

New equation of state based on the significant structure model

Prediction of solvent selectivity in extractive distillation and of vapor-liquid equilibria of hydrocarbons

High-pressure ternary liquid-liquid equilibria for the systems of water, alcohol (1-propanol, 1-butanol and 1-pentanol) and 1, 1-difluoroethane at 323.2 k