לוח שנה משולב

Nanomechanical measurements allow us to determine mechanical characteristics of nano- and microobjects, which is required for further calculations of the mechanical parameters of the structures based on them. At the same time, in-situ measurements are carried out in the SEM and TEM chambers. Thus, it is possible to acquire graphic information that can supplement the indentation data.
In this work, indentation of titania microspheres with different phase composition was tested by MEMS-based Hysitron PI-95 at Zeiss Libra 200MC TEM. Evaluation of the mechanical properties of microspheres in the elastic region was made according to the Hertz model. It turned out that annealing of the amorphous titania leads to an increase in the Young modulus, whereas the hydrothermal treatment reduces it from 27 to 4 Gpa. The differences in the destruction process was demonstrated for these kinds of particles. It has been shown, that hydrothermal treatment of titania microspheres leads to the formation of a reticular internal structure, whereas annealing results in sintering of the internal structure of microspheres.
In the process of indentation, corresponding videos were also recorded, including the probe approach, indentation, and destruction of the microspheres. In order to process the videos we coded the program based on free Python packages. Using the Digital Image Correlation (DIC) algorithm, relative probe displacements were measured during indentation (Fig. 1a). The results obtained allowed us to clarify the calibration of the movement of the indenter in free sample tests, as well as to determine the drift function in real measurements. These results are important for long-term measurements, in particular creep tests.
Based on graphical data we were able to determine the evolution of the shape of indented microspheres. During the video processing, areas of individual objects were determined, sizes of contact areas were calculated, and changes in linear dimensions of the deformed objects were determined (Fig. 1b). Therefore, a large amount of quantitative data was obtained from electron microscopy images.


Fig.1 Illustration of probe displacement determination (a) and the shape evolution analysis

Parallel transmission has been the most promising approach to counteract the radiofrequency (RF) field inhomogeneity problem in MRI at ultra-high field. Despite tremendous progress made by the community for more than a decade, the technology yet has failed to be embraced in routine practice because of a more complex safety management and a cumbersome calibration procedure for each subject in the scanner. After thorough tests and validations to address the former point, universal pulses were proposed a couple of years ago to circumvent the workflow problem in head imaging at 7T. For a given RF coil, they consist of designing, offline, pulse solutions to mitigate the RF field inhomogeneity problem while being robust to intersubject variability, all within explicit hardware and safety constraints. This talk will present the latest sequence and pulse developments incorporating these solutions, now covering 3D (GRE, MPRAGE, TSE, MP-FLAIR, DIR, 3D-EPI) and 2D (GRE, MB-EPI) sequences with first routine results for fMRI (resting-state HCP-style, localizer paradigm) and ongoing clinical studies (Multiple Sclerosis), thereby making parallel transmission one step closer to clinical routine and at zero cost for the user. Perhaps interestingly, to reach the desired versatility and simplicity, some solutions were inspired from solid-state NMR methods. To date the proposed universal pulses cumulate tests on around 50 volunteers and across 4 sites. They have never failed to return brain images virtually free of B1+ artefacts at 7T.

A census of the biomass on Earth is key for understanding the structure and dynamics of the biosphere. Yet, a quantitative, global view of how the biomass of different taxa compare with each other is still lacking. In this study, we harness recent advances in global sampling techniques to assemble the overall biomass composition of the biosphere, establishing the first census of the biomass of all the kingdoms of life.

In this talk targeted at a wide audience of chemists, I will start with a story about the ‘smartest’ molecule. Neuronal NMDA receptors, in my opinion, deserve this name, because they play the key role in the molecular mechanisms of learning, memory formation, and abstract reasoning. Also, malfunctioning NMDA receptors are involved in numerous neurological disorders, including schizophrenia, epilepsy, and Alzheimer’s disease. NMDA receptors are complicated and rich in behavior, and even the most
up-to-date experimental methods yield only a fragmented picture of these biomolecules. How do their known structures relate to their biologically relevant functional states? Through what mechanisms do post-translational modifications (specifically, glycosylation) affect their physiological properties? Computational modeling offers unique insights into these questions, and I will outline my work in this field. Simulating NMDA receptors is a formidable task, though. In the second half of my talk, I will discuss how advances in methodology could facilitate studies of such large molecular and biomolecular systems. Specifically, I will focus on the concepts of coarse-graining, Markov state modeling, and mixed-resolution hybrid modeling, highlighting my work in this field [including ultra-coarse-grained modeling, and quantum mechanics / coarse-grained molecular mechanics (QM/CG-MM) approach]. Finally, I will briefly touch on the possible use of machine learning and deep learning networks in molecular modeling. In general, further advances in the theory and methodology of modeling will result in new opportunities for studying complex phenomena, such as learning and memory, with unprecedented resolution.

Peptides in -sheet conformations have been developed in our lab in a bottom up fashion towards various biomedical applications. Hydrogels of -sheet peptides will be briefly introduced and the talk will then focus on peptide coatings for induced osseointegration of titanium implants and peptides enhanced nanoparticles for intracellularly targeted drug delivery.