In cryocrystallography, rapid sample cooling is generally deemed essential to prevent solvent crystallization and associated sample damage. We show that by carefully and completely removing all external solvent, many protein crystals can be successfully cooled to T = 100 K at only 0.1 K/s without additional penetrating cryoprotectants. Slow cooling provides an alternative when flash cooling fails, and enables diffraction studies of protein structure and function at all temperatures between T = 300 K and T = 100 K. © 2009 Springer Science+Business Media B.V.

Cryoprotectant-free thaumatin crystals have been cooled from 300 to 100 K at a rate of 0.1 K s-1 - 103-104 times slower than in conventional flash cooling - while continuously collecting X-ray diffraction data, so as to follow the evolution of protein lattice and solvent properties during cooling. Diffraction patterns show no evidence of crystalline ice at any temperature.

We study how the microscale topography of a solid surface affects the apparent advancing and receding angles at the contact line of a liquid drop pinned to this surface. Photolithographic methods are used to produce continuous circular polymer rings of varying cross-sectional size and shape on hydrophilic silicon wafer surfaces. Drops of water and glycerol are dispensed into the areas bounded by these rings, and critical apparent advancing and receding angles are measured and correlated with the parameters that characterize the ring cross section.

A stone tablet from New York University considered to be a copy of an inscription from Teanum Sidinicum is examined with X-ray fluorescence (XRF) and XRF imaging. Fluorescence spectra show many of the same elements seen in ancient Roman inscriptions, but the fluorescence intensity from calcium is much weaker and that from many other elements is much stronger. The weak calcium fluorescence cannot be due to X-ray absorption by other elements present, and so the tablet is unlikely to be of marble. This conclusion is supported by X-ray diffraction and electron microprobe measurements.

Photolithographic micropatterning is used to achieve topographic rather than chemical control of the static shape and position of microdrops on solid substrates in a gaseous ambient. Micrometer cross-section, millimeter-diameter circular rings with steep sidewalls strongly and robustly pin contact lines of nanoliter to 100 μl liquid drops, increasing the maximum stable drop volume and eliminating contact line motion due to transient accelerations.

We report electric field induced phase displacements of the charge density wave (CDW) in a single crystal of NbSe3 using Nb93 NMR spin-echo spectroscopy. CDW polarizations in the pinned state induced by unipolar and bipolar pulses are linear and reversible up to at least E=(0.96)ET. The polarizations have a broad distribution extending up to phase angles of order 60° for electric fields close to threshold. No evidence for polarizations in excess of a CDW wavelength or for a divergence in polarization near ET are observed.

Capillary tubes have many advantages over multi-well plates for macromolecular crystal growth and handling, including the possibility of in situ structure determination. To obtain complete high-resolution X-ray data sets, cryopreservation protocols must be developed to prevent crystalline ice formation and preserve macromolecular crystal order. The minimum glycerol concentrations required to vitrify aqueous solutions during plunging into liquid nitrogen and liquid propane have been determined for capillary diameters from 3.3 mm to 150 μm.

We report on a pronounced magnetic anisotropy of magnetically doped quasi-two-dimensional charge density wave (CDW) Nb Se2 at doping concentrations near 1%, and on temperature dependent reflectance, both phenomena above Nb Se2 superconducting transition (7.2 K). Unusual spikes in magnetization reversal are noticeable near 20 K, below the CDW transition (33 K), and disappear as temperature nears the superconducting transition. In the far infrared region of the spectrum, we find two sudden jumps in reflectivity, one near the CDW transition, the other near 18 K.

We have developed a technique for making low-resistance end-current injection contacts to geometrically, electronically, and mechanically anisotropic crystals of charge-density-wave (CDW) conductors. Transport measurements on Nb Se3 show that contact resistances are reduced by nearly 2 orders of magnitude compared with the standard side-contact geometry, and yield qualitatively similar results for the contact-sensitive phase-slip process.

During flash cooling of protein crystals in liquid cryogens, cooling rates are determined by sample size, choice of cooling liquid, and by the thickness of the cold gas layer that forms above the liquid. We describe an experimental protocol for ultra-rapid cooling of protein crystals. This protocol requires no complex apparatus, and yields ice-ring-free diffraction without the use of penetrating cryoprotectants. © 2007 Springer Science+Business Media B.V.