X-rays only when you want them: optimized pump-probe experiments using pseudo-single-bunch operation.

Laser pump-X-ray probe experiments require control over the X-ray pulse pattern and timing. Here, the first use of pseudo-single-bunch mode at the Advanced Light Source in picosecond time-resolved X-ray absorption experiments on solutions and solids is reported. In this mode the X-ray repetition rate is fully adjustable from single shot to 500 kHz, allowing it to be matched to typical laser excitation pulse rates. Suppressing undesired X-ray pulses considerably reduces detector noise and improves signal to noise in time-resolved experiments. In addition, dose-induced sample damage is considerably reduced, easing experimental setup and allowing the investigation of less robust samples. Single-shot X-ray exposures of a streak camera detector using a conventional non-gated charge-coupled device (CCD) camera are also demonstrated

Generation of ultrathin free-flowing liquid sheets

The physics and chemistry of liquid solutions play a central role in science, and our understanding of life on Earth. Unfortunately, key tools for interrogating aqueous systems, such as infrared and soft X-ray spectroscopy, cannot readily be applied because of strong absorption in water. Here we use gas dynamic forces to generate free-flowing, sub-micron, liquid sheets which are 2 orders of magnitude thinner than anything previously reported. Optical, infrared and X-ray spectroscopies are used to characterize the sheets, which are found to be tunable in thickness from over 1 micron down to less than 20 nanometers, which corresponds to fewer than 100 water molecules thick. At this thickness, aqueous sheets can readily transmit photons across the spectrum, leading to potentially transformative applications in infrared, X-ray, electron spectroscopies and beyond. The ultrathin sheets are stable for days in vacuum, and we demonstrate their use at free-electron laser and synchrotron light sources

Potassium uptake and homeostasis in plants grown under hostile environmental conditions, and its regulation by CBL-interacting protein kinases

Abiotic stresses impose major penalties on plant growth and agricultural crop production. Understanding the mechanisms by which plants perceive these abiotic stresses, and the subsequent signal transduction that activates their adaptive responses, is therefore of vital importance for improving plant stress tolerance in breeding programs. Among the plethora of second messengers employed by plant cells, calcineurin B–like proteins (CBLs) and CBL-interacting protein kinases (CIPKs) have emerged as critical components of the signal transduction pathways and regulators of plant ionic homeostasis under stress conditions. This chapter summarizes the current knowledge on interaction between CIPKs and K+ transport systems, and the role of the former in regulating cell ionic relations and K+ homeostasis in plants grown under adverse environmental conditions