Despina Milathianaki
Development Manager, SLAC National Accelerator Laboratory
Bio
Despina is the director of the Office of Technology Transfer and Strategic Partnerships, in the organization of the SLAC Deputy Director for Science and Technology. She and her team help accelerate the translation of cutting-edge research into transformative technologies and solutions through collaborations with industry, academia, and government partners. Before her current role, Despina served as senior director for Department of Energy partnerships in the quantum computing industry establishing important R&D efforts between the private sector and the national labs. Prior roles in the private sector included management consulting for Accenture UK and engineering for a Silicon valley startup. Despina first joined SLAC in 2010 as a staff scientist at the Linac Coherent Light Source investigating materials science at extreme conditions. She later transitioned to strategic planning where she served as the director of strategic planning and investment for SLAC. Despina holds a Bachelor's in Physics from Imperial College London and a Master’s in Electrical Engineering from the University of Michigan. She completed her PhD in High Energy Density Physics at the University of Texas at Austin, conducting research at Lawrence Livermore National Laboratory.
All Publications
- Quantum computing hardware for HEP algorithms and sensing arXiv. 2022 ; FERMILAB-PUB-22-260-SQMS
-
Ultrafast structural changes within a photosynthetic reaction centre.
Nature
2020
Abstract
Photosynthetic reaction centres harvest the energy content of sunlight by transporting electrons across an energy-transducing biological membrane. Here we use time-resolved serial femtosecond crystallography1 using an X-ray free-electron laser2 to observe light-induced structural changes in the photosynthetic reaction centre of Blastochloris viridis on a timescale of picoseconds. Structural perturbations first occur at the special pair of chlorophyll molecules of the photosynthetic reaction centre that are photo-oxidized by light. Electron transfer to the menaquinone acceptor on the opposite side of the membrane induces a movement of this cofactor together with lower amplitude protein rearrangements. These observations reveal how proteins use conformational dynamics to stabilize the charge-separation steps of electron-transfer reactions.
View details for DOI 10.1038/s41586-020-3000-7
View details for PubMedID 33268896
-
Femtosecond quantification of void evolution during rapid material failure
SCIENCE ADVANCES
2020; 6 (51)
Abstract
Understanding high-velocity impact, and the subsequent high strain rate material deformation and potential catastrophic failure, is of critical importance across a range of scientific and engineering disciplines that include astrophysics, materials science, and aerospace engineering. The deformation and failure mechanisms are not thoroughly understood, given the challenges of experimentally quantifying material evolution at extremely short time scales. Here, copper foils are rapidly strained via picosecond laser ablation and probed in situ with femtosecond x-ray free electron (XFEL) pulses. Small-angle x-ray scattering (SAXS) monitors the void distribution evolution, while wide-angle scattering (WAXS) simultaneously determines the strain evolution. The ability to quantifiably characterize the nanoscale during high strain rate failure with ultrafast SAXS, complementing WAXS, represents a broadening in the range of science that can be performed with XFEL. It is shown that ultimate failure occurs via void nucleation, growth, and coalescence, and the data agree well with molecular dynamics simulations.
View details for DOI 10.1126/sciadv.abb4434
View details for Web of Science ID 000599905500005
View details for PubMedID 33328222
View details for PubMedCentralID PMC7744076
-
Absolute Equation-of-State Measurement for Polystyrene from 25 to 60 Mbar Using a Spherically Converging Shock Wave
PHYSICAL REVIEW LETTERS
2018; 121 (2): 025001
Abstract
We have developed an experimental platform for the National Ignition Facility that uses spherically converging shock waves for absolute equation-of-state (EOS) measurements along the principal Hugoniot. In this Letter, we present one indirect-drive implosion experiment with a polystyrene sample that employs radiographic compression measurements over a range of shock pressures reaching up to 60 Mbar (6 TPa). This significantly exceeds previously published results obtained on the Nova laser [R. Cauble et al., Phys. Rev. Lett. 80, 1248 (1998)PRLTAO0031-900710.1103/PhysRevLett.80.1248] at a strongly improved precision, allowing us to discriminate between different EOS models. We find excellent agreement with Kohn-Sham density-functional-theory-based molecular dynamics simulations.
View details for DOI 10.1103/PhysRevLett.121.025001
View details for Web of Science ID 000437838000011
View details for PubMedID 30085737
-
From Macrocrystals to Microcrystals: A Strategy for Membrane Protein Serial Crystallography
STRUCTURE
2017; 25 (9): 1461-+
Abstract
Serial protein crystallography was developed at X-ray free-electron lasers (XFELs) and is now also being applied at storage ring facilities. Robust strategies for the growth and optimization of microcrystals are needed to advance the field. Here we illustrate a generic strategy for recovering high-density homogeneous samples of microcrystals starting from conditions known to yield large (macro) crystals of the photosynthetic reaction center of Blastochloris viridis (RCvir). We first crushed these crystals prior to multiple rounds of microseeding. Each cycle of microseeding facilitated improvements in the RCvir serial femtosecond crystallography (SFX) structure from 3.3-Å to 2.4-Å resolution. This approach may allow known crystallization conditions for other proteins to be adapted to exploit novel scientific opportunities created by serial crystallography.
View details for PubMedID 28781082
-
Liquid explosions induced by X-ray laser pulses
NATURE PHYSICS
2016; 12 (10): 966-971
View details for DOI 10.1038/NPHYS3779
View details for Web of Science ID 000385337700021
-
Lipidic cubic phase injector is a viable crystal delivery system for time-resolved serial crystallography
NATURE COMMUNICATIONS
2016; 7: 12314
Abstract
Serial femtosecond crystallography (SFX) using X-ray free-electron laser sources is an emerging method with considerable potential for time-resolved pump-probe experiments. Here we present a lipidic cubic phase SFX structure of the light-driven proton pump bacteriorhodopsin (bR) to 2.3 Å resolution and a method to investigate protein dynamics with modest sample requirement. Time-resolved SFX (TR-SFX) with a pump-probe delay of 1 ms yields difference Fourier maps compatible with the dark to M state transition of bR. Importantly, the method is very sample efficient and reduces sample consumption to about 1 mg per collected time point. Accumulation of M intermediate within the crystal lattice is confirmed by time-resolved visible absorption spectroscopy. This study provides an important step towards characterizing the complete photocycle dynamics of retinal proteins and demonstrates the feasibility of a sample efficient viscous medium jet for TR-SFX.
View details for DOI 10.1038/ncomms12314
View details for Web of Science ID 000381904200001
View details for PubMedID 27545823
View details for PubMedCentralID PMC4996941
-
Picosecond dynamics of a shock-driven displacive phase transformation in Zr
PHYSICAL REVIEW B
2016; 93 (14)
View details for DOI 10.1103/PhysRevB.93.144119
View details for Web of Science ID 000374531500004
-
Direct observation of ultrafast collective motions in CO myoglobin upon ligand dissociation
SCIENCE
2015; 350 (6259): 445–50
Abstract
The hemoprotein myoglobin is a model system for the study of protein dynamics. We used time-resolved serial femtosecond crystallography at an x-ray free-electron laser to resolve the ultrafast structural changes in the carbonmonoxy myoglobin complex upon photolysis of the Fe-CO bond. Structural changes appear throughout the protein within 500 femtoseconds, with the C, F, and H helices moving away from the heme cofactor and the E and A helices moving toward it. These collective movements are predicted by hybrid quantum mechanics/molecular mechanics simulations. Together with the observed oscillations of residues contacting the heme, our calculations support the prediction that an immediate collective response of the protein occurs upon ligand dissociation, as a result of heme vibrational modes coupling to global modes of the protein.
View details for PubMedID 26359336
-
Ultrafast visualization of crystallization and grain growth in shock-compressed SiO<sub>2</sub> (vol 6, 8191, 2015)
NATURE COMMUNICATIONS
2015; 6
View details for DOI 10.1038/ncomms9709
View details for Web of Science ID 000363017100019
-
The Matter in Extreme Conditions instrument at the Linac Coherent Light Source
JOURNAL OF SYNCHROTRON RADIATION
2015; 22: 520-525
Abstract
The LCLS beam provides revolutionary capabilities for studying the transient behavior of matter in extreme conditions. The particular strength of the Matter in Extreme Conditions instrument is that it combines the unique LCLS beam with high-power optical laser beams, and a suite of dedicated diagnostics tailored for this field of science. In this paper an overview of the beamline, the capabilities of the instrumentation, and selected highlights of experiments and commissioning results are presented.
View details for DOI 10.1107/S1600577515004865
View details for Web of Science ID 000353920300010
View details for PubMedID 25931063
View details for PubMedCentralID PMC4416670
-
The Coherent X-ray Imaging instrument at the Linac Coherent Light Source
JOURNAL OF SYNCHROTRON RADIATION
2015; 22: 514–19
Abstract
The Coherent X-ray Imaging (CXI) instrument specializes in hard X-ray, in-vacuum, high power density experiments in all areas of science. Two main sample chambers, one containing a 100 nm focus and one a 1 µm focus, are available, each with multiple diagnostics, sample injection, pump-probe and detector capabilities. The flexibility of CXI has enabled it to host a diverse range of experiments, from biological to extreme matter.
View details for DOI 10.1107/S160057751500449X
View details for Web of Science ID 000353920300009
View details for PubMedID 25931062
View details for PubMedCentralID PMC4416669
-
Optical laser systems at the Linac Coherent Light Source
JOURNAL OF SYNCHROTRON RADIATION
2015; 22: 526–31
Abstract
Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump-probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manuscript describes the laser systems and experimental methods that enable cutting-edge optical laser/X-ray pump-probe experiments to be performed at LCLS.
View details for PubMedID 25931064
View details for PubMedCentralID PMC4416671
-
Time-resolved serial crystallography captures high-resolution intermediates of photoactive yellow protein
SCIENCE
2014; 346 (6214): 1242-1246
Abstract
Serial femtosecond crystallography using ultrashort pulses from x-ray free electron lasers (XFELs) enables studies of the light-triggered dynamics of biomolecules. We used microcrystals of photoactive yellow protein (a bacterial blue light photoreceptor) as a model system and obtained high-resolution, time-resolved difference electron density maps of excellent quality with strong features; these allowed the determination of structures of reaction intermediates to a resolution of 1.6 angstroms. Our results open the way to the study of reversible and nonreversible biological reactions on time scales as short as femtoseconds under conditions that maximize the extent of reaction initiation throughout the crystal.
View details for DOI 10.1126/science.1259357
View details for Web of Science ID 000346189000061
View details for PubMedID 25477465
View details for PubMedCentralID PMC4361027
-
Serial time-resolved crystallography of photosystem II using a femtosecond X-ray laser
NATURE
2014; 513 (7517): 261-?
Abstract
Photosynthesis, a process catalysed by plants, algae and cyanobacteria converts sunlight to energy thus sustaining all higher life on Earth. Two large membrane protein complexes, photosystem I and II (PSI and PSII), act in series to catalyse the light-driven reactions in photosynthesis. PSII catalyses the light-driven water splitting process, which maintains the Earth's oxygenic atmosphere. In this process, the oxygen-evolving complex (OEC) of PSII cycles through five states, S0 to S4, in which four electrons are sequentially extracted from the OEC in four light-driven charge-separation events. Here we describe time resolved experiments on PSII nano/microcrystals from Thermosynechococcus elongatus performed with the recently developed technique of serial femtosecond crystallography. Structures have been determined from PSII in the dark S1 state and after double laser excitation (putative S3 state) at 5 and 5.5 Å resolution, respectively. The results provide evidence that PSII undergoes significant conformational changes at the electron acceptor side and at the Mn4CaO5 core of the OEC. These include an elongation of the metal cluster, accompanied by changes in the protein environment, which could allow for binding of the second substrate water molecule between the more distant protruding Mn (referred to as the 'dangler' Mn) and the Mn3CaOx cubane in the S2 to S3 transition, as predicted by spectroscopic and computational studies. This work shows the great potential for time-resolved serial femtosecond crystallography for investigation of catalytic processes in biomolecules.
View details for DOI 10.1038/nature13453
View details for Web of Science ID 000341362800056
View details for PubMedCentralID PMC4821544
-
Visualizing a protein quake with time-resolved X-ray scattering at a free-electron laser
NATURE METHODS
2014; 11 (9): 923–26
Abstract
We describe a method to measure ultrafast protein structural changes using time-resolved wide-angle X-ray scattering at an X-ray free-electron laser. We demonstrated this approach using multiphoton excitation of the Blastochloris viridis photosynthetic reaction center, observing an ultrafast global conformational change that arises within picoseconds and precedes the propagation of heat through the protein. This provides direct structural evidence for a 'protein quake': the hypothesis that proteins rapidly dissipate energy through quake-like structural motions.
View details for PubMedID 25108686
View details for PubMedCentralID PMC4149589
-
Taking snapshots of photosynthetic water oxidation using femtosecond X-ray diffraction and spectroscopy
NATURE COMMUNICATIONS
2014; 5
Abstract
The dioxygen we breathe is formed by light-induced oxidation of water in photosystem II. O2 formation takes place at a catalytic manganese cluster within milliseconds after the photosystem II reaction centre is excited by three single-turnover flashes. Here we present combined X-ray emission spectra and diffraction data of 2-flash (2F) and 3-flash (3F) photosystem II samples, and of a transient 3F' state (250 μs after the third flash), collected under functional conditions using an X-ray free electron laser. The spectra show that the initial O-O bond formation, coupled to Mn reduction, does not yet occur within 250 μs after the third flash. Diffraction data of all states studied exhibit an anomalous scattering signal from Mn but show no significant structural changes at the present resolution of 4.5 Å. This study represents the initial frames in a molecular movie of the structural changes during the catalytic reaction in photosystem II.
View details for DOI 10.1038/ncomms5371
View details for Web of Science ID 000340615500062
View details for PubMedID 25006873
View details for PubMedCentralID PMC4151126
-
Accurate macromolecular structures using minimal measurements from X-ray free-electron lasers
NATURE METHODS
2014; 11 (5): 545-548
Abstract
X-ray free-electron laser (XFEL) sources enable the use of crystallography to solve three-dimensional macromolecular structures under native conditions and without radiation damage. Results to date, however, have been limited by the challenge of deriving accurate Bragg intensities from a heterogeneous population of microcrystals, while at the same time modeling the X-ray spectrum and detector geometry. Here we present a computational approach designed to extract meaningful high-resolution signals from fewer diffraction measurements.
View details for DOI 10.1038/NMETH.2887
View details for Web of Science ID 000335873400020
View details for PubMedID 24633409
View details for PubMedCentralID PMC4008696
-
Combined Hydrodynamic and Diffraction Simulations of Femtosecond X-ray Scattering from Laser-Shocked Crystals
IOP PUBLISHING LTD. 2014
View details for DOI 10.1088/1742-6596/500/15/152016
View details for Web of Science ID 000337722900230
-
Femtosecond Visualization of Lattice Dynamics in Shock-Compressed Matter
SCIENCE
2013; 342 (6155): 220-223
Abstract
The ultrafast evolution of microstructure is key to understanding high-pressure and strain-rate phenomena. However, the visualization of lattice dynamics at scales commensurate with those of atomistic simulations has been challenging. Here, we report femtosecond x-ray diffraction measurements unveiling the response of copper to laser shock-compression at peak normal elastic stresses of ~73 gigapascals (GPa) and strain rates of 10(9) per second. We capture the evolution of the lattice from a one-dimensional (1D) elastic to a 3D plastically relaxed state within a few tens of picoseconds, after reaching shear stresses of 18 GPa. Our in situ high-precision measurement of material strength at spatial (<1 micrometer) and temporal (<50 picoseconds) scales provides a direct comparison with multimillion-atom molecular dynamics simulations.
View details for DOI 10.1126/science.1239566
View details for Web of Science ID 000325475200038
View details for PubMedID 24115435
-
Simultaneous Femtosecond X-ray Spectroscopy and Diffraction of Photosystem II at Room Temperature
SCIENCE
2013; 340 (6131): 491-495
Abstract
Intense femtosecond x-ray pulses produced at the Linac Coherent Light Source (LCLS) were used for simultaneous x-ray diffraction (XRD) and x-ray emission spectroscopy (XES) of microcrystals of photosystem II (PS II) at room temperature. This method probes the overall protein structure and the electronic structure of the Mn4CaO5 cluster in the oxygen-evolving complex of PS II. XRD data are presented from both the dark state (S1) and the first illuminated state (S2) of PS II. Our simultaneous XRD-XES study shows that the PS II crystals are intact during our measurements at the LCLS, not only with respect to the structure of PS II, but also with regard to the electronic structure of the highly radiation-sensitive Mn4CaO5 cluster, opening new directions for future dynamics studies.
View details for DOI 10.1126/science.1234273
View details for Web of Science ID 000318016700046
View details for PubMedID 23413188
-
Nanoflow electrospinning serial femtosecond crystallography
ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY
2012; 68: 1584-1587
Abstract
An electrospun liquid microjet has been developed that delivers protein microcrystal suspensions at flow rates of 0.14-3.1 µl min(-1) to perform serial femtosecond crystallography (SFX) studies with X-ray lasers. Thermolysin microcrystals flowed at 0.17 µl min(-1) and diffracted to beyond 4 Å resolution, producing 14,000 indexable diffraction patterns, or four per second, from 140 µg of protein. Nanoflow electrospinning extends SFX to biological samples that necessitate minimal sample consumption.
View details for DOI 10.1107/S0907444912038152
View details for Web of Science ID 000310069500017
View details for PubMedID 23090408
View details for PubMedCentralID PMC3478121
-
A Seeman-Bohlin geometry for high-resolution nanosecond x-ray diffraction measurements from shocked polycrystalline and amorphous materials
REVIEW OF SCIENTIFIC INSTRUMENTS
2009; 80 (9): 093904
Abstract
We report on a focusing x-ray diffraction geometry capable of high-resolution in situ lattice probing from dynamically loaded polycrystalline and amorphous materials. The Seeman-Bohlin-type camera presented here is ideally suited for time-resolved x-ray diffraction measurements performed on high energy multibeam laser platforms. Diffraction from several lattice planes of ablatively shock-loaded 25 mum thick Cu foils was recorded on a focusing circle of diameter D=100 mm with exceptional angular resolution limited only by the spectral broadening of the x-ray source. Excellent agreement was found between the density measured using x-ray diffraction and that inferred from Doppler velocimetry and the known shock Hugoniot of Cu. In addition, x-ray diffraction signal was captured from an amorphous material under static conditions.
View details for DOI 10.1063/1.3230647
View details for Web of Science ID 000270380000025
View details for PubMedID 19791950
-
Laser-induced spall of aluminum and aluminum alloys at high strain rates
AMER INST PHYSICS. 2007: 501-+
View details for Web of Science ID 000252158500118