Sub-micrometer focusing setup for high-pressure crystallography at the Extreme Conditions beamline at PETRA III

Scientific tasks aimed at decoding and characterizing complex systems and processes at high pressures set new challenges for modern X-ray diffraction instrumentation in terms of X-ray flux, focal spot size and sample positioning. Presented here are new developments at the Extreme Conditions beamline (P02.2, PETRA III, DESY, Germany) that enable considerable improvements in data collection at very high pressures and small scattering volumes. In particular, the focusing of the X-ray beam to the sub-micrometer level is described, and control of the aberrations of the focusing compound refractive lenses is made possible with the implementation of a correcting phase plate. This device provides a significant enhancement of the signal-to-noise ratio by conditioning the beam shape profile at the focal spot. A new sample alignment system with a small sphere of confusion enables single-crystal data collection from grains of micrometer to sub-micrometer dimensions subjected to pressures as high as 200 GPa. The combination of the technical development of the optical path and the sample alignment system contributes to research and gives benefits on various levels, including rapid and accurate diffraction mapping of samples with sub-micrometer resolution at multimegabar pressures.

New dynamic diamond anvil cells for tera-pascal per second fast compression x-ray diffraction experiments

Fast compression experiments performed using dynamic diamond anvil cells (dDACs) employing piezoactuators offer the opportunity to study compression-rate dependent phenomena. In this paper, we describe an experimental setup which allows us to perform time-resolved x-ray diffraction during the fast compression of materials using improved dDACs. The combination of the high flux available using a 25.6 keV x-ray beam focused with a linear array of compound refractive lenses and the two fast GaAs LAMBDA detectors available at the Extreme Conditions Beamline (P02.2) at PETRA III enables the collection of x-ray diffraction patterns at an effective repetition rate of up to 4 kHz. Compression rates of up to 160 TPa/s have been achieved during the compression of gold in a 2.5 ms fast compression using improved dDAC configurations with more powerful piezoactuators. The application of this setup to low-Z compounds at lower compression rates is described, and the high temporal resolution of the setup is demonstrated. The possibility of applying finely tuned pressure profiles opens opportunities for future research, such as using oscillations of the piezoactuator to mimic propagation of seismic waves in the Earth.

Pure Natural Orifice Transluminal Endoscopic Surgery (NOTES) with a new elongated, curved Transanal Endoscopic Operation (TEO) device for rectosigmoid resection: a survival study in a porcine model

BACKGROUND

Natural orifice transluminal endoscopic surgery (NOTES) has seen considerable new developments in its evolution to a platform for rectal and sigmoid resection, but to date no true single NOTES procedure has been convincing. This study investigates the safety and feasibility of a further developed transanal NOTES platform for single-access NOTES rectosigmoid resection.

METHODS

Ten large female pigs, mean weight 99.3 kg [standard deviation (SD) 7 kg, range 85.1-112.6 kg], underwent transanal rectosigmoid resection. Five animals were included in an acute study group with immediate postoperative euthanization. A second group included five animals in a survival study. Transanal rectosigmoid resections were performed with an elongated and curved transanal endoscopic operation (TEO) device. Coloanal anastomosis was performed using the transanal circular stapler technique. Survival follow-up was at 7 and 28 days via colonoscopy under sedation.

RESULTS

Single-access NOTES transanal rectosigmoid resection with coloanal anastomosis was performed in nine out of ten female pigs. Mean length of rectosigmoid specimens exteriorized was 18.7 cm (SD 2.9 cm, range 14-23 cm). Mean operating time was 124 min (SD 35.7 min, range 70-166 min). Within the survival group, no complications occurred during the monitoring phase. In one case, there was ascites and colitis at necropsy as well as fibrosis at the anastomosis site.

CONCLUSIONS

Pure transanal rectosigmoid resection is a feasible procedure. The approach via a single transanal access is demanding but viable with the elongated and curved TEO device. The newly developed scope offers an excellent view of the area cephalad to the promontory.

[Not Available]

An analytical method for the detection of fusaric acid in wheat and wheat products has been developed as well as employed for the survey of randomly selected samples (n=33). While the application of GC-FID proved to be not sensitive enough for this purpose, the sensitivity and selectivity of GC-MS permitted the quantification of the mycotoxin in 78% of the wheat samples.The measured concentrations ranged from 7 to 570 μg/kg (average value 134 μg/kg). However, clear differences were recognizable regarding the type of sample: While field samples showed 332 μg/kg on an average, cleaned grains designated for human consumption contained averaged 138 μg/kg, and wholemeal products 68 μg/kg.Although the limited number of samples does not permit final conclusions, the toxicological relevance of fusaric acid alone may probably be classified as small. To what extent the well known cumulative effects with deoxynivalenol and fumonisin B1 impair this evaluation has to remain elusive.