This work examines the effect of perturbing the position of bound CO 2 in the active site of human carbonic anhydrase II (HCA II) on catalysis. Variants of HCA II in which Val143 was replaced with hydrophobic residues Ile, Leu, and Ala were examined. The efficiency of catalysis in the hydration of CO2 for these variants was characterized by 18O exchange mass spectrometry, and their structures were determined by X-ray crystallography at 1.7-1.5 Å resolution.

We report the room temperature formation of aminated mesoporous silica nanoparticles (NH 2-MSNs) by means of co-condensation of different molar ratios of tetraethyl orthosilicate (TEOS) and 3-aminopropyl triethoxysilane (APTES) in the synthesis feed. The resulting materials are characterized by a combination of transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and N 2 adsorption/desorption measurements.

Structure determination of proteins and other macromolecules has historically required the growth of high-quality crystals sufficiently large to diffract x-rays efficiently while withstanding radiation damage. We applied serial femtosecond crystallography (SFX) using an x-ray free-electron laser (XFEL) to obtain high-resolution structural information from microcrystals (less than 1 micrometer by 1 micrometer by 3 micrometers) of the well-characterized model protein lysozyme.

Background: In the cellular environment, macromolecules occupy about 30% of a cell's volume. In this crowded environment, proteins behave very differently than in dilute solution where scientists typically study the properties of proteins. For this reason, recent studies have investigated proteins in cell-like crowded conditions so as to understand if this changes their properties. The present study was performed to examine if molecular crowding impedes the protein unfolding process that is known to occur upon the application of high pressure.

Figure Persented: The production of high-performance carbon nanotube (CNT) materials demands understanding of the growth behavior of individual CNTs as well as collective effects among CNTs. We demonstrate the first use of grazing incidence small-angle X-ray scattering to monitor in real time the synthesis of CNT films by chemical vapor deposition. We use a custom-built cold-wall reactor along with a high-speed pixel array detector resulting in a time resolution of 10 msec.

Single-particle imaging experiments of biomolecules at x-ray free-electron lasers (XFELs) require processing hundreds of thousands of images that contain very few x-rays. Each low-fluence image of the diffraction pattern is produced by a single, randomly oriented particle, such as a protein. We demonstrate the feasibility of recovering structural information at these extremes using low-fluence images of a randomly oriented 2D x-ray mask.

The design of the FPGA Pixel Array Detector (PAD) prototype and initial experimental results of real-time implementations of its autocorrelation function are presented. This is a pixelated 2D silicon device for detecting X-rays in X-ray Diffraction Experiments and is comprised of three layers: the diode detection and ASIC analog electronics layers connected by a massively parallel interface to a third FPGA layer consisting of a Xilinx XC6VLX550T device. A high-speed labor intensive asynchronous interface as well as a more traditional synchronous interface will be presented.

Small-angle X-ray scattering (SAXS) was performed on single-crystal chemical vapor deposition (CVD) diamonds with low nitrogen concentrations, which were fabricated by microwave plasma-assisted chemical vapor deposition at high growth rates. High optical quality undoped 500 m-thick single-crystal CVD diamonds grown without intentional nitrogen addition proved to be excellent as windows on SAXS cells, yielding parasitic scattering no more intense than a 7.5 m-thick Kapton film. A single-crystal CVD diamond window was successfully used in a high-pressure SAXS cell.

Multicomponent materials with ordered nanoscale networks are critical for applications ranging from microelectronics to energy conversion and storage devices which require charge transport along 3-dimensional (3D) continuous pathways. The network symmetry can facilitate additional properties such as macroscopic polarization for piezoelectric, pyroelectric, and second-order nonlinear optical properties in non-centrosymmetric morphologies. Although pure block copolymers are able to form multiple network morphologies, network tunability remains a challenge for coassembled systems.