The copolymer poly(DL-lactic acid-co-glycolic acid), used in the design of nanoparticles as drug delivery systems, forms stable monolayers at the air/water interface when spread from solutions of chloroform or 4:1 (v:v) chloroform-ethanol mixtures. The -A curves obtained show a plateau at a surface pressure of about 9 mN-m'1, corresponding to a change from high to low compressibility monolayer states. Since the surface pressure in the plateau region was hardly altered by increasing temperature from 10 to 35 °C, the plateau is interpreted as reflecting compression-induced reorientation of the polar groups of the polymer. There was marked hysteresis when the film was compressed to the collapse surface pressure (60 mN-m"1) and then expanded to its initial area: the first compression-expansion cycle did not return the monolayer to its original state, probably due to irreversible loss of molecules during collapse. Below the collapse surface pressure, however, the film showed reversible behavior.

The properties of high-concentration titanium dioxide slurries under UV irradiation were (Evonik Aeroxide® P25) at concentrations of 0.5, 1, 1.5, 2 and 2.5 g L-1 were irradiated by a mercury lamp (254 nm). At neutral pH, within the studied concentration range, nanoparticles form agglomerates of tens of micrometers. Their size, measured by optical microscopy, increases linearly with catalyst concentration. The attenuation length of the UV radiation was measured by a spectrophotometer with an integrating sphere. The concentration of the model contaminant (Orange II) was determined by spectrophotometry at intervals of 20 minutes, during the irradiation time (6 hours). The measured values fit satisfactorily to a pseudo first order kinetics. At catalyst concentrations of 1 g L-1 and higher, the kinetic constant is (8.1 ± 0.5) x 10-3 min-1. This is explained by the diminution of the attenuation length and the simultaneous increase of the total exposed surface at higher catalyst concentrations.

This work presents a model of an annular batch slurry photocatalytic reactor using titanium dioxide at high concentrations and pH close to 7. The model considers the effects of the agglomeration of catalyst particles that take place when the reactor operates close to neutral pH. It also includes the adsorption/desorption equilibrium of the contaminant on the catalyst during 1 h in darkness, followed by the photochemical reaction under UV irradiation. The reactor was modelled by a system of differential equations solved using the Micro‐Cap 12 program. This powerful software package numerically solves the differential equations as an equivalent network, providing a convenient graphical interface for model programming and plotting of results. The model was validated with measurements at several catalyst concentrations from 1–2.5 g/L. Aeroxide P25, supplied by Evonik, was used as catalyst, with UV irradiation at a wavelength of 254 nm. Orange II, a widely used azo dye, was chosen as the model contaminant. The model results were in satisfactory agreement with the experimental data. Simulations were carried out with different initial conditions, to analyze the influence of the system variables on the performance of the reactor. In this way, the optimal design criteria at high catalyst concentrations were found. The mathematical model is simple and robust and can be applied in a straightforward way to the design and scaling of photocatalytic reactors. It is also particularly attractive for educational purposes.

The search for neutrinoless double beta decay (0νββ) remains one of the most compelling experimental avenues for the discovery in the neutrino sector. Electroluminescent gas-phase time projection chambers are well suited to 0νββ searches due to their intrinsically precise energy resolution and topological event identification capabilities. Scalability to ton- and multi-ton masses requires readout of large-area electroluminescent regions with fine spatial resolution, low radiogenic backgrounds, and a scalable data acquisition system. This paper presents a detector prototype that records event topology in an electroluminescent xenon gas TPC via VUV image-intensified cameras. This enables an extendable readout of large tracking planes with commercial devices that reside almost entirely outside of the active medium. Following further development in intermediate scale demonstrators, this technique may represent a novel and enlargeable method for topological event imaging in 0νββ.

Silicic acid produces marked expansion in dipalmitoyl lecithin films and in mixed cholesterol-dipalmitoyl lecithin films with more than 50 % phospholipid. In the presence of silicic acid, these films no longer exhibit a transition region between the liquid-expanded and liquid-condensed states. Mixed cholesterol-dilauroyl lecithin films are also expanded by silicic acid. In the absence of silicic acid, the addition of cholesterol produces greater condensation in dilauroyl lecithin films than in films of dipalmitoyl lecithin, but the reverse is the case if the substrate contains silicic acid. These resuks have been interpreted in terms of a possible electrostatic interaction between negatively charged dissociated silicate ions and the positively charged trimethyl ammonium group of the choline fragment.