The performance of a capacitance-wire wave recorder
A capacitanoe-wire wave recorder circuit was used in conjunction with a p.t»f,e. wire probe to establish what errors are associated with using such a system for the measurement of small waves. In the experiments the probe was moved relative to the water, rather than vico versa and both photographic and electrical methods were employed to investigate the errors introduced by the meniscus, the wetting of the wire and the effects of wire thickness on the wave shapes. The electrical methods involved accurate recording of the probe movement by means of a linear potentiometer and a comparison of this movement with the wave form produced from the circuit measuring the chasige in capacitance of the probe caused by its movement in the water. The effects of increasing the operation! frequency of the recording circuit was also investigated.
Determination of the profiles of water waves
Tlw tvqmitor tjpc depth gayqe, dest'rihc~rl in //lis pq)pr, record the longitudinal proliles ancl cross-zectinns or undular faci/itntes n('cu/'n/i7 rei~~rdings (I/ t/7~ profi/rs o/ //ITPP surgc w;ivcs produced in ii prismoidnl channel. Thcsc waves r/itliPnsiona/ li'(1ter li'fmJLs propn,qo/er/ in prisnroir/n/ o/)en are produced when il sudden sustiiincd quontity or water is i~/iantir/s. The circuitry, priticip/e ant/ cnlihrotion of' //if, discharged into the ch;inncl. which contains an initial level gni/~~:~ nre out/ined, ii*it/i pnrtic.u/nr rqfirenc-r 10 //re of still water. The wave cross-scction is obtained by comnt1i-an~age.r <! f ' usinK srnnriurd indusrricd equipnretrr. piling the records from it number of probes on and offset
An anionic shell shields a cationic core allowing for uptake and release of polyelectrolytes within core-shell responsive microgels.
To realize carriers for drug delivery, cationic containers are required for anionic guests. Nevertheless, the toxicity of cationic carriers limits their practical use. In this study, we investigate a model system of polyampholyte N-isopropylacrylamide (NIPAM)-based microgels with a cationic core and an anionic shell to study whether the presence of a negative shell allows the cationic core to be shielded while still enabling the uptake and release of the anionic guest polyelectrolytes. These microgels are loaded with polystyrene sulfonate of different molecular weights to investigate the influence of their chain length on the uptake and release process. By means of small-angle neutron scattering, we evaluate the spatial distribution of polystyrene sulfonate within the microgels. The guest molecules are located in different parts of the core-shell microgels depending on their size. By combining these scattering results with UV-vis spectroscopy, electrophoretic mobility and potentiometric titrations we gain complementary results to investigate the uptake and release process of polyelectrolytes in polyampholyte core-shell microgels. Moreover, Brownian molecular dynamic simulations are performed to compare the experimental and theoretical results of this model. Our findings demonstrate that the presence of a shell still enables efficient uptake of guest molecules into the cationic core. These anionic guest molecules can be released through an anionic shell. Furthermore, the presence of a shell enhances the stability of the microgel-polyelectrolyte complexes with respect to the cationic precursor microgel alone.