Phase Heterogeneity in Cholesterol-Containing Ternary Phospholipid Lamellar Phases.

Pseudo-ternary mixtures of lamellar phase phospholipids (DPPC and brain sphingomyelin with cholesterol) were studied below T m while comparing the influence of cholesterol content, temperature, and the presence of small quantities of vitamin D binding protein (DBP) or vitamin D receptor (VDR). The measurements, conducted by X-ray diffraction (XRD) and nuclear magnetic resonance (NMR), cover a range of cholesterol concentrations (20% mol. wt to 40% mol. wt.) and physiologically relevant temperature range (294-314 K). In addition to rich intraphase behavior, data and modeling are used to approximate the lipids' headgroup location variations under the abovementioned experimental conditions.

Data from multi year and multi radiation detector measurements of different radiation sources with environmental data.

The data described consists of radiation measurement outputs from several different detectors located in Abu Dhabi, UAE, for the duration of 30 November 2014 through 13 December 2016. This data could be useful for anyone studying radiation count rate or spectroscopic changes over a multi year period from various radiation sources and measurement systems. The outputs of the measurement systems include 1) counts per 20 min from a Geiger-Muller detector measuring 90Sr, 2) counts per 20 min from a Geiger-Muller detector measuring 204Tl, 3) radiation spectra per 30 min from a NaI detector measuring 60Co, 4) radiation spectra per 30 min from a NaI detector measuring 54Mn, 5) radiation spectra per 30 min from a liquid scintillation detector measuring 226Ra, 6) counts per 30 min from a liquid scintillation detector measuring 14C, and room pressure, temperature, and humidity data every 10 min. A detailed description of the setup of each of these measurement systems can be found in "Experimental Setup and Commissioning Baseline Study in Search of Time-Variations in Beta-Decay Half-Lives" [1].

Therapeutic vitamin delivery: Chemical and physical methods with future directions.

Vitamins are a diverse group of "life nourishing" molecules that are essential for proper childhood development, and for maintaining health throughout adulthood into old age. Vitamin supplementation is an important strategy for reducing the severe and chronic effects of malnutrition in subsets of the population of the developing world. Additionally, the precise role of many vitamins in certain conditions, including cancer and cardiovascular disease, remains an area of active research, although guidelines for vitamin supplementation in otherwise adequately nourished populations remain controversial. This review describes vitamin delivery methods and techniques, focusing on the most recent advances and novel approaches. Specific attention has been given to physical methods and novel formulations for delivery with an emphasis on reporting pros and cons of each technique and highlighting future directions. Of particular interest is the potential for transdermal delivery of certain vitamins, which is an approach that may provide advantages in some populations (e.g. for vitamin D), but that still requires considerable additional research and clinical validation.

Spatial dependence and mitigation of radiation damage by a line-focus mini-beam.

Recently, strategies to reduce primary radiation damage have been proposed which depend on focusing X-rays to dimensions smaller than the penetration depth of excited photoelectrons. For a line focus as used here the penetration depth is the maximum distance from the irradiated region along the X-ray polarization direction that the photoelectrons penetrate. Reported here are measurements of the penetration depth and distribution of photoelectron damage excited by 18.6 keV photons in a lysozyme crystal. The experimental results showed that the penetration depth of ~17.35 keV photoelectrons is 1.5 ± 0.2 µm, which is well below previous theoretical estimates of 2.8 µm. Such a small penetration depth raises challenging technical issues in mitigating damage by line-focus mini-beams. The optimum requirements to reduce damage in large crystals by a factor of 2.0-2.5 are Gaussian line-focus mini-beams with a root-mean-square width of 0.2 µm and a distance between lines of 2.0 µm. The use of higher energy X-rays (> 26 keV) would help to alleviate some of these requirements by more than doubling the penetration depth. It was found that the X-ray dose has a significant contribution from the crystal's solvent, which initially contained 9.0%(w/v) NaCl. The 15.8 keV photoelectrons of the Cl atoms and their accompanying 2.8 keV local dose from the decay of the resulting excited atoms more than doubles the dose deposited in the X-ray-irradiated region because of the much greater cross-section and higher energy of the excited atom, degrading the mitigation of radiation damage from 2.5 to 2.0. Eliminating heavier atoms from the solvent and data collection far from heavy-atom absorption edges will significantly improve the mitigation of damage by line-focus mini-beams.

One-dimensional hard x-ray field retrieval using a moveable structure.

We present a technique that allows measuring the field of an x-ray line focus using far-field intensity measurements only. One-dimensional phase retrieval with transverse translation diversity is used to recover a hard x-ray beam focused by a compound kinoform lens. The reconstruction is found to be in good agreement with independent knife-edge scan measurements taken at separated planes. The approach avoids the need for measuring the beam profile at focus and allows narrower beams to be measured than the traditional knife-edge scan.