A patterned hydrogel was immobilized on a polymer substrate by low-pressure argon plasma treatment using a masking technique. The polymer sample showed a thermoresponsive aggregation behavior in the region of 35-37 degrees C. The micropatterned, thermoresponsive hydrogel film has been characterized with imaging ellipsometry. The characterization was carried out on the dry film as well as on a swollen sample in water. The thermoresponsive behavior was studied in deionized water by temperature-dependent measurements in a solid-liquid cell. Through imaging ellipsometry, it was possible to distinguish the different regions of interest on a micrometer scale and to follow the swelling of the hydrogel part as a function of the temperature. It was possible to visualize the swelling as 3D profiles of Delta at various temperatures. Long-term changes of the sample could also be detected, which cannot be picked up by conventional ellipsometry.

The understanding of tissue damage by laser radiation is very important for the safety in the application of surgical lasers. The objective of this study is to evaluate cutting, vaporization and coagulation properties of the 2 µm Tm:YAG laser (LISA Laser Products OHG, GER) in comparison to the 2.1 µm Ho:YAG laser (Coherent Medical Group, USA) at different laser power settings in an in vitro model of freshly harvested porcine kidneys. Laser radiation of both laser generators was delivered by using a laser fiber with an optical core diameter of 550 µm (RigiFib, LISA Laser GER). Freshly harvested porcine kidneys were used as tissue model. Experiments were either performed in ambient air or in aqueous saline. The Tm:YAG laser was adjusted to 5 W for low and 120 W for the high power setting. The Ho:YAG laser was adjusted to 0.5 J and 10 Hz (5 W average power) for low power setting and to 2.0 J and 40 Hz (80 W average power) for high power setting, accordingly. The specimens of the cutting experiments were fixed in 4 % formalin, embedded in paraffin and stained with Toluidin blue. The laser damage zone was measured under microscope as the main evaluation criteria. Laser damage zone consists of an outer coagulation zone plus a further necrotic zone. In the ambient air experiments the laser damage zone for the low power setting was 745 ± 119 µm for the Tm:YAG and 614 ± 187 µm for the Ho:YAG laser. On the high power setting, the damage zone was 760 ± 167 µm for Tm:YAG and 715 ± 142 µm for Ho:YAG. The incision depth in ambient air on the low power setting was 346 ± 199 µm for Tm:YAG, 118 ± 119 µm for Ho:YAG. On the high power setting incision depth was 5083 ± 144 µm (Tm:YAG) and 1126 ± 383 µm (Ho:YAG) respectively. In the saline solution experiments, the laser damage zone was 550 ± 137 µm (Tm:YAG) versus 447 ± 65 µm (Ho:YAG), on the low power setting and 653 ± 137 µm (Tm:YAG) versus 677 ± 134 µm (Ho:YAG) on the high power setting. Incision depth was 1214 ± 888 µm for Ho:YAG whereas Tm:YAG did not cut tissue at 5 W in saline solution. On the high power setting, the incision depth was 4050 ± 1058 µm for Tm:YAG and 4083 ± 520 µm for Ho:YAG. Both lasers create similar laser damage zones of <1 mm in ambient air and in saline solution. These in vitro experiments correspond well with in vivo experiments. Thereby, Tm:YAG offers a cutting performance, coagulation and safety profile similar to the standard Ho:YAG lasers in urological surgery.

Model development to predict transformation of sulfonylureas in different matrices was carried out using multiple linear regression. Descriptors for lipophilicity and molecular topology, as well as quantum chemical descriptors for energy, geometry, polarity, charges and reactivity using MOPAC with three different Hamiltonians, AM1, PM3 and MNDO, were calculated. In addition, experimental descriptors were measured and taken from the literature. End-points were transformation rates of twelve sulfonylurea herbicides in buffers at different pH (4, 7 and 10), in sterile and native sediments, and in sterile and native soil. Inter-correlation of reaction rates indicated four different groups of transformation types, for which sum parameters were calculated. (1) Hydrolysis at pH 4 could be estimated with pKa and charges at a specific atom of the heterocycle. (2) Hydrolysis at pH 7 and 10, as well as transformation in sterile sediments and soil, could be described with descriptors for reactivity (polarisability and superdelocalisability) at specific atoms of the molecules. (3) For transformation in native sediments different models could be found, all based on descriptors for polarisability, superdelocalisability and charges at specific atoms. (4) Modelling of biotransformation in native soil led to diverse models with a variety of descriptors reflecting electronic properties and lipophilicity. Models confirmed previous findings on reaction mechanisms and thereby prove valuable not only for quantitative prediction of reaction rates, but also for studies on transformation pathways.

Quantitative relationships between the structure of phenylurea herbicides and their transformation in different matrices have been developed. Experimental data on microbial transformation by pure and mixed cultures of soil micro-organisms in inoculated and native soil, as well as on chemical transformation by hydrolysis in sterile soil and water, were available from previous studies. Around 60 experimental or calculated descriptors were used. Quantum chemical calculations were performed with three different semi-empirical methods. Models developed with multiple linear regression were generally easier to interpret than those derived with partial least-squares projection to latent structures. Quite simple and interpretable models could be found to predict transformation rates by pure cultures from lipophilicity, by mixed cultures from adsorption distribution coefficients, and by chemical or enzymatic hydrolysis from electronic properties. Transformation in inoculated soil could not be predicted, but for native soil the use of a quantum chemical descriptor for reactivity (energy of LUMO) together with molar refraction resulted in a general model.