APPLICATION OF GEORGIAN NATURAL ANALCIME FOR PRODUCTION OF ION EXCHANGERS

Analcime is a fairly widespread zeolite in the territory of Georgia and other countries, but its practical application is limited due to the peculiarities of its compact structure with small pores and irregular channels. This work describes a method developed by us for hydrothermal recrystallization of analcime into a widely used ion exchanger of the LTA type in the form of micrometric crystals or nanosized crystals, depending on the synthesis conditions. Silver-, copper-and zinc-containing analcimes and synthetic LTA zeolites with bacteriostatic activity were obtained by ion exchange. It has been shown that the highest bacteriostatic activity is possessed by a silver-containing synthetic zeolite, and analcimes enriched with relatively cheap copper and zinc exhibit activity sufficient for practical use in water treatment, paper production and other applications.

MicroED with the Falcon III direct electron detector

Microcrystal electron diffraction (MicroED) combines crystallography and electron cryo-microscopy (cryo-EM) into a method that is applicable to high-resolution structure determination. In MicroED, nanosized crystals, which are often intractable using other techniques, are probed by high-energy electrons in a transmission electron microscope. Diffraction data are recorded by a camera in movie mode: the nanocrystal is continuously rotated in the beam, thus creating a sequence of frames that constitute a movie with respect to the rotation angle. Until now, diffraction-optimized cameras have mostly been used for MicroED. Here, the use of a direct electron detector that was designed for imaging is reported. It is demonstrated that data can be collected more rapidly using the Falcon III for MicroED and with markedly lower exposure than has previously been reported. The Falcon III was operated at 40 frames per second and complete data sets reaching atomic resolution were recorded in minutes. The resulting density maps to 2.1 Å resolution of the serine protease proteinase K showed no visible signs of radiation damage. It is thus demonstrated that dedicated diffraction-optimized detectors are not required for MicroED, as shown by the fact that the very same cameras that are used for imaging applications in electron microscopy, such as single-particle cryo-EM, can also be used effectively for diffraction measurements.

MicroED with the Falcon III direct electron detector

Microcrystal electron diffraction (MicroED) combines crystallography and electron cryomicroscopy (cryo-EM) into a method that can be used for high-resolution structure determination. In MicroED nanosized crystals, often intractable by other techniques, are probed by high-energy electrons in a transmission electron microscope and the diffracted signal is recorded on an electron detector. Since only a small number of different detectors have been used for MicroED measurements in the past, their impact on data quality has not been investigated. Here we evaluate two different cameras using crystals of the well-characterized serine protease proteinase K. Compared to previously used equipment, the Falcon III direct electron detector and the CMOS-based CetaD camera can collect complete datasets both faster and using lower total exposure. As an effect of the lower dose, radiation damage is reduced, which is confirmed in both real and reciprocal space. The increased speed and lower exposure requirements have implications on model quality and the prospects for further automation of MicroED.

Pulsed laser deposition of single-layer MoS2 on Au(111): from nanosized crystals to large-area films

Molybdenum disulphide (MoS2) is a promising material for heterogeneous catalysis and novel 2D optoelectronic devices. In this work, single-layer MoS2 is synthesized on Au(111) by pulsed laser deposition, showing the potentialities of this technique in the synthesis of high-quality 2D materials films.