Publications by authors named "Esther H R Tsai"

15 Publications

  • Page 1 of 1

Direct evidence for eoarchean iron metabolism?

Geobiology 2021 Feb 24. Epub 2021 Feb 24.

Globe Institute, University of Copenhagen, Copenhagen, Denmark.

Metasedimentary rocks from Isua, West Greenland (> 3,700 million years old) contain carbonaceous compounds, compatible with a biogenic origin (Hassenkam, Andersson, Dalby, Mackenzie, & Rosing, 2017; Ohtomo, Kakegawa, Ishida, Nagase, & Rosing, 2014; Rosing, 1999). The metamorphic mineral assemblage with garnet and quartz intergrowths contains layers of carbonaceous inclusions contiguous with carbon-rich sedimentary beds in the host rock. Previous studies (Hassenkam et al., 2017; Ohtomo et al., 2014; Rosing, 1999) on Isua rocks focused on testing the biogenic origin of the carbonaceous material, but here we searched for evidence which could provide new insights into the nature of the life that generated this carbonaceous material. We studied material trapped in inclusions armoured within quartz grains inside garnet porphyroblasts by non-destructive ptychographic X-ray nanotomography (PXCT). The 3D electron density maps generated by PXCT were correlated with maps from X-ray fluorescence tomography and micro-Raman spectroscopy. We found that the material trapped inside inclusions in the quartz grains consist of disordered carbon material encasing domains of iron-rich carbonaceous material. These results corroborate earlier claims (Hassenkam et al., 2017; Ohtomo et al., 2014; Rosing, 1999) for biogenic origins and are compatible with relics of metamorphosed biological material originally containing high iron/carbon ratios, comparable to ratios found in most extant organisms. These iron-rich domains represent the oldest evidence for organic iron complexes in the geologic record and are consistent with Fe-isotopic evidence for metabolic iron fractionation in > 3,700 Ma Isua banded iron formation (Czaja et al., 2013; Whitehouse & Fedo, 2007).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/gbi.12432DOI Listing
February 2021

An Integrated Design of a Polypseudorotaxane-Based Sea Cucumber Mimic.

Angew Chem Int Ed Engl 2021 Feb 19. Epub 2021 Feb 19.

Department of Chemistry, Dartmouth College, Hanover, NH, 03755, USA.

The development of integrated systems that mimic the multi-stage stiffness change of marine animals such as the sea cucumber requires the design of molecularly tailored structures. Herein, we used an integrated biomimicry design to fabricate a sea cucumber mimic using sidechain polypseudorotaxanes with tunable nano-to-macroscale properties. A series of polyethylene glycol (PEG)-based sidechain copolymers were synthesized to form sidechain polypseudorotaxanes with α-cyclodextrins (α-CDs). By tailoring the copolymers' molecular weights and their PEG grafting densities, we rationally tuned the sizes of the formed polypseudorotaxanes crystalline domain and the physical crosslinking density of the hydrogels, which facilitated 3D printing and the mechanical adaptability to these hydrogels. After 3D printing and photo-crosslinking, the obtained hydrogels exhibited large tensile strain and broad elastic-to-plastic variations upon α-CD (de)threading. These discoveries enabled a successful fabrication of a sea cucumber mimic, demonstrating multi-stage stiffness changes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.202017019DOI Listing
February 2021

Large-Grained Cylindrical Block Copolymer Morphologies by One-Step Room-Temperature Casting.

Macromolecules 2020 Dec 1;53(24):11178-11189. Epub 2020 Dec 1.

Department of Chemistry, University of Warsaw, Warsaw 02089, Poland.

We report a facile method of ordering block copolymer (BCP) morphologies in which the conventional two-step casting and annealing steps are replaced by a single-step process where microphase separation and grain coarsening are seamlessly integrated within the casting protocol. This is achieved by slowing down solvent evaporation during casting by introducing a nonvolatile solvent into the BCP casting solution that effectively prolongs the duration of the grain-growth phase. We demonstrate the utility of this solvent evaporation annealing (SEA) method by producing well-ordered large-molecular-weight BCP thin films in a total processing time shorter than 3 min without resorting to any extra laboratory equipment other than a basic casting device, ., spin- or blade-coater. By analyzing the morphologies of the quenched samples, we identify a relatively narrow range of polymer concentration in the wet film, just above the order-disorder concentration, to be critical for obtaining large-grained morphologies. This finding is corroborated by the analysis of the grain-growth kinetics of horizontally oriented cylindrical domains where relatively large growth exponents (1/2) are observed, indicative of a more rapid defect-annihilation mechanism in the concentrated BCP solution than in thermally annealed BCP melts. Furthermore, the analysis of temperature-resolved kinetics data allows us to calculate the Arrhenius activation energy of the grain coarsening in this one-step BCP ordering process.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.macromol.0c02026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7759006PMC
December 2020

Alterations in Sub-Axonal Architecture Between Normal Aging and Parkinson's Diseased Human Brains Using Label-Free Cryogenic X-ray Nanotomography.

Front Neurosci 2020 25;14:570019. Epub 2020 Nov 25.

Paul Scherrer Institut, Villigen, Switzerland.

Gaining insight to pathologically relevant processes in continuous volumes of unstained brain tissue is important for a better understanding of neurological diseases. Many pathological processes in neurodegenerative disorders affect myelinated axons, which are a critical part of the neuronal circuitry. Cryo ptychographic X-ray computed tomography in the multi-keV energy range is an emerging technology providing phase contrast at high sensitivity, allowing label-free and non-destructive three dimensional imaging of large continuous volumes of tissue, currently spanning up to 400,000 μm. This aspect makes the technique especially attractive for imaging complex biological material, especially neuronal tissues, in combination with downstream optical or electron microscopy techniques. A further advantage is that dehydration, additional contrast staining, and destructive sectioning/milling are not required for imaging. We have developed a pipeline for cryo ptychographic X-ray tomography of relatively large, hydrated and unstained biological tissue volumes beyond what is typical for the X-ray imaging, using human brain tissue and combining the technique with complementary methods. We present four imaged volumes of a Parkinson's diseased human brain and five volumes from a non-diseased control human brain using cryo ptychographic X-ray tomography. In both cases, we distinguish neuromelanin-containing neurons, lipid and melanic pigment, blood vessels and red blood cells, and nuclei of other brain cells. In the diseased sample, we observed several swellings containing dense granular material resembling clustered vesicles between the myelin sheaths arising from the cytoplasm of the parent oligodendrocyte, rather than the axoplasm. We further investigated the pathological relevance of such swollen axons in adjacent tissue sections by immunofluorescence microscopy for phosphorylated alpha-synuclein combined with multispectral imaging. Since cryo ptychographic X-ray tomography is non-destructive, the large dataset volumes were used to guide further investigation of such swollen axons by correlative electron microscopy and immunogold labeling post X-ray imaging, a possibility demonstrated for the first time. Interestingly, we find that protein antigenicity and ultrastructure of the tissue are preserved after the X-ray measurement. As many pathological processes in neurodegeneration affect myelinated axons, our work sets an unprecedented foundation for studies addressing axonal integrity and disease-related changes in unstained brain tissues.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fnins.2020.570019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7724048PMC
November 2020

, a versatile high-level framework for high-performance analysis of ptychographic data.

J Appl Crystallogr 2020 Apr 13;53(Pt 2):574-586. Epub 2020 Mar 13.

Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.

Over the past decade, ptychography has been proven to be a robust tool for non-destructive high-resolution quantitative electron, X-ray and optical microscopy. It allows for quantitative reconstruction of the specimen's transmissivity, as well as recovery of the illuminating wavefront. Additionally, various algorithms have been developed to account for systematic errors and improved convergence. With fast ptychographic microscopes and more advanced algorithms, both the complexity of the reconstruction task and the data volume increase significantly. is a software package which combines high-level modularity for easy and fast changes to the data-processing pipeline, and high-performance computing on CPUs and GPUs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1107/S1600576720001776DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7133065PMC
April 2020

Crystal structure and orientation of organic semiconductor thin films by microcrystal electron diffraction and grazing-incidence wide-angle X-ray scattering.

Chem Commun (Camb) 2020 Apr;56(30):4204-4207

Chemical Engineering, School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ 85287, USA. and Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA.

We use microcrystal electron diffraction (MicroED) to determine structures of three organic semiconductors, and show that these structures can be used along with grazing-incidence wide-angle X-ray scattering (GIWAXS) to understand crystal packing and orientation in thin films. Together these complimentary techniques provide unique structural insights into organic semiconductor thin films, a class of materials whose device properties and electronic behavior are sensitively dependent on solid-state order.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/d0cc00119hDOI Listing
April 2020

A lathe system for micrometre-sized cylindrical sample preparation at room and cryogenic temperatures.

J Synchrotron Radiat 2020 Mar 29;27(Pt 2):472-476. Epub 2020 Jan 29.

Photon Science Division, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland.

A simple two-spindle based lathe system for the preparation of cylindrical samples intended for X-ray tomography is presented. The setup can operate at room temperature as well as under cryogenic conditions, allowing the preparation of samples down to 20 and 50 µm in diameter, respectively, within minutes. Case studies are presented involving the preparation of a brittle biomineral brachiopod shell and cryogenically fixed soft brain tissue, and their examination by means of ptychographic X-ray computed tomography reveals the preparation method to be mainly free from causing artefacts. Since this lathe system easily yields near-cylindrical samples ideal for tomography, a usage for a wide variety of otherwise challenging specimens is anticipated, in addition to potential use as a time- and cost-saving tool prior to focused ion-beam milling. Fast sample preparation becomes especially important in relation to shorter measurement times expected in next-generation synchrotron sources.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1107/S1600577519017028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064112PMC
March 2020

Gridrec-MS: an algorithm for multi-slice tomography.

Opt Lett 2019 May;44(9):2181-2184

Advances in imaging systems and modeling allow for depth information to be retrieved from projections via virtual sectioning of the imaged object. Here we introduce a regridding method that explicitly and directly incorporates this information into a general and non-iterative tomographic reconstruction algorithm. The method is applicable to any imaging scheme that provides depth-resolved projections. Additionally, we show, via numerical simulations, that with this method the required number of projections for adequate angular sampling can be reduced.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OL.44.002181DOI Listing
May 2019

Correlated X-Ray 3D Ptychography and Diffraction Microscopy Visualize Links between Morphology and Crystal Structure of Lithium-Rich Cathode Materials.

iScience 2019 Jan 31;11:356-365. Epub 2018 Dec 31.

Swiss Light Source, Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland. Electronic address:

The search for higher performance, improved safety, and lifetime of lithium-ion batteries relies on the understanding of degradation mechanisms. Complementary to methods and studies on primary particles or crystalline structure on bulk materials, here we use spatially correlated ptychographic X-ray computed nanotomography with a 35 nm resolution and scanning X-ray diffraction microscopy with 1 μm resolution to visualize in 3D the hidden morphological and structural degradation processes in individual secondary particles of lithium-rich nickel, cobalt, and manganese oxides. From comparative examination of pristine and cycled particles, we suggest that morphological degradation could have radial dependency and secondary particle size dependency. The same particles were examined to correlate the degradation to crystallinity, which shows surprising core-shell structures. This study reveals the inner 3D structure of the secondary particles while opening up questions on the unexpected crystalline structural distributions, which could offer clues for future studies on this promising cathode material for lithium-ion batteries.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.isci.2018.12.028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6348281PMC
January 2019

Ptychographic X-ray CT characterization of the osteocyte lacuno-canalicular network in a male rat's glucocorticoid induced osteoporosis model.

Bone Rep 2018 Dec 29;9:122-131. Epub 2018 Jul 29.

Synchrotron Soleil, L'Orme des Merisiers, 91192 Gif-sur-Yvette, France.

Ptychographic X-ray computed tomography (PXCT) is a quantitative imaging modality that non-destructively maps the 3D electron density inside an object with tens of nanometers spatial resolution. This method provides unique access to the morphology and structure of the osteocyte lacuno-canalicular network (LCN) and nanoscale density of the tissue in the vicinity of an osteocyte lacuna. Herein, we applied PXCT to characterize the lacunae and LCN in a male Wistar rat model of glucocorticoid-induced osteoporosis (GIO). The ptychographic images revealed significant (p < 0.05) differences in the number of canaliculi originating from the lacuna per ellipsoidal surface unit, Ca.Nb (p = 0.0106), and the 3D morphology of the lacuna (p = 0.0064), between GIO and SHAM groups. Moreover, the mean canalicular diameter, Ca.Dm, was slightly statistically un-significantly smaller in GIO (152 ± 6.5) nm than in SHAM group (165 ± 8) nm (p = 0.053). Our findings indicate that PXCT can non-destructively provide detailed, nanoscale information on the 3D organization of the LCN in correlative studies of pathologies, such as osteoporosis, leading to improved diagnosis and therapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bonr.2018.07.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6146379PMC
December 2018

High-resolution non-destructive three-dimensional imaging of integrated circuits.

Nature 2017 03;543(7645):402-406

Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.

Modern nanoelectronics has advanced to a point at which it is impossible to image entire devices and their interconnections non-destructively because of their small feature sizes and the complex three-dimensional structures resulting from their integration on a chip. This metrology gap implies a lack of direct feedback between design and manufacturing processes, and hampers quality control during production, shipment and use. Here we demonstrate that X-ray ptychography-a high-resolution coherent diffractive imaging technique-can create three-dimensional images of integrated circuits of known and unknown designs with a lateral resolution in all directions down to 14.6 nanometres. We obtained detailed device geometries and corresponding elemental maps, and show how the devices are integrated with each other to form the chip. Our experiments represent a major advance in chip inspection and reverse engineering over the traditional destructive electron microscopy and ion milling techniques. Foreseeable developments in X-ray sources, optics and detectors, as well as adoption of an instrument geometry optimized for planar rather than cylindrical samples, could lead to a thousand-fold increase in efficiency, with concomitant reductions in scan times and voxel sizes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/nature21698DOI Listing
March 2017

X-ray ptychography with extended depth of field.

Opt Express 2016 Dec;24(25):29089-29108

Ptychographic X-ray computed tomography is a coherent diffractive imaging method that offers nanometer-scale resolution with quantitative contrast. It offers the possibility to study relatively thick samples by using high energy X-ray photons and exploiting the phase contrast. However, the limited depth of field forces a compromise between resolution and sample thickness. Multi-slice techniques have been used to account for propagation effects within the sample, enabling imaging beyond the depth-of-field limit. Here we introduce and experimentally demonstrate our multi-slice algorithms that allow for the reconstruction of multiple object slices and the incident illumination, as well as the retrieval of unknown object thickness. Additionally, through numerical studies, we show that smaller scanning steps surprisingly increase the depth of field, which can be further extended by the use of multi-slice methods under conditions stated by theoretical expressions. The results presented here will be instrumental for the routine implementation of the technique for X-ray nanotomography.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.24.029089DOI Listing
December 2016

X-ray ptychography using a distant analyzer.

Opt Express 2016 Mar;24(6):6441-50

Ptychography has offered unparalleled high resolution in hard X-ray imaging. However, the imaging quality relies on the interaction between the object and the illumination to be well described by a mathematical model in the reconstruction algorithm. Here, we demonstrate at X-ray wavelengths a method that allows for reconstruction of the object exit wavefield without the need for the knowledge of this interaction. The incident field interacts with the object, and the exit wavefield propagates freely to the plane of an analyzer. As we translate the analyzer and measure diffraction patterns, the propagated wavefield can be reconstructed and the object exit wavefield determined by numerical backpropagation. The method broadens the impact and application of ptychography as it offers information inaccessible to conventional ptychography as well as working distances of tens of millimeters.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/OE.24.006441DOI Listing
March 2016

Fabrication and application of heterogeneous printed mouse phantoms for whole animal optical imaging.

Appl Opt 2016 Jan;55(2):280-7

This work demonstrates the usefulness of 3D printing for optical imaging applications. Progress in developing optical imaging for biomedical applications requires customizable and often complex objects for testing and evaluation. There is therefore high demand for what have become known as tissue-simulating "phantoms." We present a new optical phantom fabricated using inexpensive 3D printing methods with multiple materials, allowing for the placement of complex inhomogeneities in complex or anatomically realistic geometries, as opposed to previous phantoms, which were limited to simple shapes formed by molds or machining. We use diffuse optical imaging to reconstruct optical parameters in 3D space within a printed mouse to show the applicability of the phantoms for developing whole animal optical imaging methods. This phantom fabrication approach is versatile, can be applied to optical imaging methods besides diffusive imaging, and can be used in the calibration of live animal imaging data.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5652317PMC
http://dx.doi.org/10.1364/AO.55.000280DOI Listing
January 2016

In vivo mouse fluorescence imaging for folate-targeted delivery and release kinetics.

Biomed Opt Express 2014 Aug 17;5(8):2662-78. Epub 2014 Jul 17.

Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA.

Many cancer cells over-express folate receptors, and this provides an opportunity for both folate-targeted fluorescence imaging and the development of targeted anti-cancer drugs. We present an optical imaging modality that allows for the monitoring and evaluation of drug delivery and release through disulfide bond reduction inside a tumor in vivo for the first time. A near-infrared folate-targeting fluorophore pair was synthesized and used to image a xenograft tumor grown from KB cells in a live mouse. The in vivo results are shown to be in agreement with previous in vitro studies, confirming the validity and feasibility of our method as an effective tool for preclinical studies in drug development.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1364/BOE.5.002662DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4132996PMC
August 2014