Reply to: Ultrafast evolution and transient phases of a prototype out-of-equilibrium Mott-Hubbard material

International audienceReplying to D. Moreno-Mencía et al. Nature Communicationshttps://doi.org/10.1038/s41467-019-11743-3 (2019)

Three-dimensional holographic optical tweezers implemented on spatial light modulator

We have developed a holographic optical tweezers system based on diffractive optical elements (DOES) implementedon a liquid crystal spatial light modulator (LC-SLM) able to generate fine positioned traps on the sample. Our ownalgorithms and code allows to calculate phase DOES that can transform a single laser beam into an array of independenttraps, each with individually specified characteristics, arranged in arbitrary three-dimensional (3D) geometricalconfigurations. Different DOEs can be dynamically projected to the SLM in order to achieve a rearrangement of theconfiguration of the trapping spots. Silica or latex micro-beads are trapped in different configurations of spots todemonstrate the fine control capability on each trap. Our setup is built on a standard video microscope coupled with alaser source, a spatial light modulator and a three axis nano-positioning system. It allows to obtain 3D multi-trappingand a fine calibration for the positioning of the traps

Technical advances and future perspectives in liver surgery

The current era of liver surgery is high- lighted by low morbidity and mortality rates, inno- vative efforts to increase resectability, and overall improved survival for patients with both primary and metastatic lesions. The complexity of liver anatomy combined with the presence of several major vascu- lar structures delayed the widespread application of minimally invasive surgical techniques to liver surgery compared to other intra-abdominal organs. However, our experience with minimally invasive surgery has greatly expanded over the past 20 years. Modern sur- gical techniques, emerging technologies, and novel chemotherapeutic agents have led to a significant increase in minimally invasive liver surgery world- wide. This review will focus on the modern technical advancements that make minimally invasive liver surgery successful and what we can expect in the future

Wave front engineering for microscopy of living cells

A new method to perform simultaneously three dimensional optical sectioning and optical manipulation is presented. The system combines a multi trap optical tweezers with a video microscope to enable axial scanning of living cells while maintaining the trapping configuration at a fixed position. This is achieved compensating the axial movement of the objective by shaping the wave front of the trapping beam with properly diffractive optical elements displayed on a computer controlled spatial light modulator. Our method has been validated in three different experimental configurations. In the first, we decouple the position of a trapping plane from the axial movements of the objective and perform optical sectioning of a circle of beads kept on a fixed plane. In a second experiment, we extend the method to living cell microscopy by showing that mechanical constraints can be applied on the dorsal surface of a cell whilst performing its fluorescence optical sectioning. In the third experiment, we trapped beads in a three dimensional geometry and perform, always through the same objective, an axial scan of the volume delimited by the beads

Biological samples micro-manipulation by means of optical tweezers

The goal of this work is to investigate the usefulness of the optical tweezers for biological sample micro-manipulation. We report multiple optical trapping and manipulation of Escherichia coli cells, immersed in growth medium, by means of diffractive optical elements (DOE). The DOEs are implemented on a spatial light modulator to generate movable geometries of traps. We report also an experiment that allows to mimic the mechanical environment of cells in tissues. Micro-meter sized beads are trapped in circular geometry in order to surround living cells. By dynamically varying the geometry of the configuration and the trapping forces, we can reproduce a controlled environment where only mechanical stimuli are present and biological responses can be monitored. These experiments have been implemented in two different setups. In the first, cell manipulation is performed by the use of two-dimensional optical tweezers system generated by dual axis acousto-optical deflectors. In the second setup, trapping configuration is extended to three-dimensional volumes using DOEs

Three-dimensional holographic optical tweezers implemented on spatial light modulator

We have developed a holographic optical tweezers system based on diffractive optical elements (DOES) implementedon a liquid crystal spatial light modulator (LC-SLM) able to generate fine positioned traps on the sample. Our ownalgorithms and code allows to calculate phase DOES that can transform a single laser beam into an array of independenttraps, each with individually specified characteristics, arranged in arbitrary three-dimensional (3D) geometricalconfigurations. Different DOEs can be dynamically projected to the SLM in order to achieve a rearrangement of theconfiguration of the trapping spots. Silica or latex micro-beads are trapped in different configurations of spots todemonstrate the fine control capability on each trap. Our setup is built on a standard video microscope coupled with alaser source, a spatial light modulator and a three axis nano-positioning system. It allows to obtain 3D multi-trappingand a fine calibration for the positioning of the traps.</p

Steatotic livers. Can we use them in OLTX? Outcome data from a prospective baseline liver biopsy study

Introduction. Steatotic livers have been associated with greater risk of allograft dysfunction in liver transplantation. Our aim was to determinate the prevalence of steatosis in grafts from deceased donors in Chile and to assess the utility of a protocol-bench biopsy as an outcome predictor of steatotic grafts in our transplant program.Material and methods. We prospectively performed protocol-bench graft biopsies from March 2004 to January 2009. Biopsies were analyzed and classified by two independent pathologists. Steatosis severity was graded as normal from absent to 33-66% and grade 3: > 66%.Results. We analyzed 58 liver grafts from deceased donors. Twenty-nine grafts (50%) were steatotic; 9 of them (16%) with grade 3. Donor age (p < 0.001) and BMI over 25 kg/m2 (p = 0.012) were significantly associated with the presence of steatosis. There were two primary non-functions (PNF); both in a grade 3 steatotic graft. The 3-year overall survival was lower among recipients with macrovesicular steatotic graft (57%) than recipients with microvesicular (85%) or non-steatotic grafts (95%) (p = 0.026).Conclusion. Macro-vesicular steatosis was associated with a poor outcome in this series. A protocol bench-biopsy would be useful to identify these grafts