Correlative operando microscopy of oxygen evolution electrocatalysts.

Transition metal (oxy)hydroxides are promising electrocatalysts for the oxygen evolution reaction1-3. The properties of these materials evolve dynamically and heterogeneously4 with applied voltage through ion insertion redox reactions, converting materials that are inactive under open circuit conditions into active electrocatalysts during operation5. The catalytic state is thus inherently far from equilibrium, which complicates its direct observation. Here, using a suite of correlative operando scanning probe and X-ray microscopy techniques, we establish a link between the oxygen evolution activity and the local operational chemical, physical and electronic nanoscale structure of single-crystalline ß-Co(OH)2 platelet particles. At pre-catalytic voltages, the particles swell to form an α-CoO2H1.5·0.5H2O-like structure-produced through hydroxide intercalation-in which the oxidation state of cobalt is +2.5. Upon increasing the voltage to drive oxygen evolution, interlayer water and protons de-intercalate to form contracted ß-CoOOH particles that contain Co3+ species. Although these transformations manifest heterogeneously through the bulk of the particles, the electrochemical current is primarily restricted to their edge facets. The observed Tafel behaviour is correlated with the local concentration of Co3+ at these reactive edge sites, demonstrating the link between bulk ion-insertion and surface catalytic activity.

X-ray linear dichroic ptychography.

Biominerals such as seashells, coral skeletons, bone, and tooth enamel are optically anisotropic crystalline materials with unique nanoscale and microscale organization that translates into exceptional macroscopic mechanical properties, providing inspiration for engineering new and superior biomimetic structures. Using Seriatopora aculeata coral skeleton as a model, here, we experimentally demonstrate X-ray linear dichroic ptychography and map the c-axis orientations of the aragonite (CaCO3) crystals. Linear dichroic phase imaging at the oxygen K-edge energy shows strong polarization-dependent contrast and reveals the presence of both narrow (<35°) and wide (>35°) c-axis angular spread in the coral samples. These X-ray ptychography results are corroborated by four-dimensional (4D) scanning transmission electron microscopy (STEM) on the same samples. Evidence of co-oriented, but disconnected, corallite subdomains indicates jagged crystal boundaries consistent with formation by amorphous nanoparticle attachment. We expect that the combination of X-ray linear dichroic ptychography and 4D STEM could be an important multimodal tool to study nano-crystallites, interfaces, nucleation, and mineral growth of optically anisotropic materials at multiple length scales.

Correlative image learning of chemo-mechanics in phase-transforming solids.

Constitutive laws underlie most physical processes in nature. However, learning such equations in heterogeneous solids (for example, due to phase separation) is challenging. One such relationship is between composition and eigenstrain, which governs the chemo-mechanical expansion in solids. Here we developed a generalizable, physically constrained image-learning framework to algorithmically learn the chemo-mechanical constitutive law at the nanoscale from correlative four-dimensional scanning transmission electron microscopy and X-ray spectro-ptychography images. We demonstrated this approach on LiXFePO4, a technologically relevant battery positive electrode material. We uncovered the functional form of the composition-eigenstrain relation in this two-phase binary solid across the entire composition range (0 ≤ X ≤ 1), including inside the thermodynamically unstable miscibility gap. The learned relation directly validates Vegard's law of linear response at the nanoscale. Our physics-constrained data-driven approach directly visualizes the residual strain field (by removing the compositional and coherency strain), which is otherwise impossible to quantify. Heterogeneities in the residual strain arise from misfit dislocations and were independently verified by X-ray diffraction line profile analysis. Our work provides the means to simultaneously quantify chemical expansion, coherency strain and dislocations in battery electrodes, which has implications on rate capabilities and lifetime. Broadly, this work also highlights the potential of integrating correlative microscopy and image learning for extracting material properties and physics.

Fictitious phase separation in Li layered oxides driven by electro-autocatalysis.

Layered oxides widely used as lithium-ion battery electrodes are designed to be cycled under conditions that avoid phase transitions. Although the desired single-phase composition ranges are well established near equilibrium, operando diffraction studies on many-particle porous electrodes have suggested phase separation during delithiation. Notably, the separation is not always observed, and never during lithiation. These anomalies have been attributed to irreversible processes during the first delithiation or reversible concentration-dependent diffusion. However, these explanations are not consistent with all experimental observations such as rate and path dependencies and particle-by-particle lithium concentration changes. Here, we show that the apparent phase separation is a dynamical artefact occurring in a many-particle system driven by autocatalytic electrochemical reactions, that is, an interfacial exchange current that increases with the extent of delithiation. We experimentally validate this population-dynamics model using the single-phase material Lix(Ni1/3Mn1/3Co1/3)O2 (0.5 < x < 1) and demonstrate generality with other transition-metal compositions. Operando diffraction and nanoscale oxidation-state mapping unambiguously prove that this fictitious phase separation is a repeatable non-equilibrium effect. We quantitatively confirm the theory with multiple-datastream-driven model extraction. More generally, our study experimentally demonstrates the control of ensemble stability by electro-autocatalysis, highlighting the importance of population dynamics in battery electrodes (even non-phase-separating ones).

Discrete dipole approximation for lossy plasmonic background.

The discrete dipoles approximation method is exploited to study light scattering near a cylindrical cavity, made in an absorbing plasmonic surrounding medium. To the best of our knowledge, this is the first use of the method for the metal background. Our two-dimensional numerical simulation of the local fields demonstrates a good performance of the approach. Its high accuracy is proven by comparison with the known analytical solution.

Measuring spectroscopy and magnetism of extracted and intracellular magnetosomes using soft X-ray ptychography.

Characterizing the chemistry and magnetism of magnetotactic bacteria (MTB) is an important aspect of understanding the biomineralization mechanism and function of the chains of magnetosomes (Fe3O4 nanoparticles) found in such species. Images and X-ray absorption spectra (XAS) of magnetosomes extracted from, and magnetosomes in, whole Magnetovibrio blakemorei strain MV-1 cells have been recorded using soft X-ray ptychography at the Fe 2p edge. A spatial resolution of 7 nm is demonstrated. Precursor-like and immature magnetosome phases in a whole MV-1 cell were visualized, and their Fe 2p spectra were measured. Based on these results, a model for the pathway of magnetosome biomineralization for MV-1 is proposed. Fe 2p X-ray magnetic circular dichroism (XMCD) spectra have been derived from ptychography image sequences recorded using left and right circular polarization. The shape of the XAS and XMCD signals in the ptychographic absorption spectra of both sample types is identical to the shape and signals measured with conventional bright-field scanning transmission X-ray microscope. A weaker and inverted XMCD signal was observed in the ptychographic phase spectra of the extracted magnetosomes. The XMCD ptychographic phase spectrum of the intracellular magnetosomes differed from the ptychographic phase spectrum of the extracted magnetosomes. These results demonstrate that spectro-ptychography offers a superior means of characterizing the chemical and magnetic properties of MTB at the individual magnetosome level.

Increasing the cervical and lumbar lordosis is possible despite overt osteoarthritis and spinal stenosis using extension traction to relieve low back and leg pain in a 66-year-old surgical candidate: a CBP® case report.

[Purpose] To present the case of the dramatic relief of low back pain, leg pain and disability in an older female with osteoarthritis, lumbar spinal stenosis and hypolordosis of the cervical and lumbar spine. [Participant and Methods] A 66-year-old female presented with chronic low back pain, right leg pain, numbness and weakness. Despite being recommended for surgery, the patient sought alternative treatment. The patient was treated with Chiropractic BioPhysics® rehabilitation of the spine with the objective to increase the lumbar and cervical lordoses. Cervical and lumbar extension exercises and traction were performed as well as spinal manipulation. Treatment was performed approximately three times per week for 6.5 months. [Results] Re-assessment after treatment demonstrated significant reduction of low back pain, leg pain and other health improvements. X-rays showed structural improvements in the cervical and lumbar spine despite advanced osteoarthritis. [Conclusion] Lumbar and cervical hypolordosis subluxation may be increased in those with spinal deformity caused symptoms, despite the presence of osteoarthritis and degenerative stenosis of the spine. Spinal x-rays as used in the assessment and monitoring of patients being treated with contemporary spinal rehabilitation methods are not harmful and should be used for routine screening purposes.

Alleviation of neck pain by the non-surgical rehabilitation of a pathologic cervical kyphosis to a normal lordosis: a CBP® case report.

[Purpose] To present a case of the therapeutic reversal of a cervical kyphosis into a lordosis in a patient who presented with neck pain and headaches. [Subject and Methods] A 24-year-old male irritated his neck while dancing. Upon examination it was revealed he had an excessive, 45 mm forward head translation and a 15° cervical kyphosis from C3-C6. The patient was treated with Chiropractic BioPhysics® methods aimed at restoring the cervical lordosis by mirror image®, neck extension exercises, cervical extension traction, and spinal manipulative therapy. [Results] After two weeks of treatments the patient reported a complete resolution of neck pain. After 24 treatments over 10-weeks, a lateral radiograph demonstrated the restoration of a cervical lordosis and a complete reduction of forward head translation. [Conclusion] This case demonstrates that a cervical kyphosis may be reversed into a lordosis in as little as 10-weeks by specific care incorporating cervical extension protocols. This case also supports the biomechanical literature that suggests those with cervical kyphosis may be predisposed to spinal injury. We suggest that correcting even asymptomatic patients with obvious cervical spine deformity should be accomplished prior to future injury and/or degenerative changes.

Frustration of the total reflection by a hidden scatterer.

The scattering of a wave by a cylindric object hidden within the dielectric is studied. The total reflection is frustrated because of the scattering. Magnetic and electric fields at the dielectric surface and the energy flux are calculated by the modified boundary element method at near-field and far-field distances. The total reflection is shown to rearrange the shape of a scattering indicatrix.

Dependence on Crystal Size of the Nanoscale Chemical Phase Distribution and Fracture in LixFePO4.

The performance of battery electrode materials is strongly affected by inefficiencies in utilization kinetics and cycle life as well as size effects. Observations of phase transformations in these materials with high chemical and spatial resolution can elucidate the relationship between chemical processes and mechanical degradation. Soft X-ray ptychographic microscopy combined with X-ray absorption spectroscopy and electron microscopy creates a powerful suite of tools that we use to assess the chemical and morphological changes in lithium iron phosphate (LiFePO4) micro- and nanocrystals that occur upon delithiation. All sizes of partly delithiated crystals were found to contain two phases with a complex correlation between crystallographic orientation and phase distribution. However, the lattice mismatch between LiFePO4 and FePO4 led to severe fracturing on microcrystals, whereas no mechanical damage was observed in nanoplates, indicating that mechanics are a principal driver in the outstanding electrode performance of LiFePO4 nanoparticles. These results demonstrate the importance of engineering the active electrode material in next generation electrical energy storage systems, which will achieve theoretical limits of energy density and extended stability. This work establishes soft X-ray ptychographic chemical imaging as an essential tool to build comprehensive relationships between mechanics and chemistry that guide this engineering design.

"The times they are a-changin'"*: 25 years of psychotherapy research--a European and Latin American perspective.

OBJECTIVE: This article discusses the 25th anniversary of the journal Psychotherapy research from a European perspective. METHOD: Based upon the reflections of one of the founding editors of the journal (David A. Shapiro), together with overviews from SPR colleagues, this article focuses on the major developments in the field of psychotherapy research in the U.K., Germany, as well as and other European countries, as well as Portugal, Spain, and Latin America. RESULTS: The Society for Psychotherapy Research (SPR), which founded the journal as its official organ, underwent a metamorphosis from a purely North American to an international scientific organization during the 1980s. The move towards a greater international audience has been mirrored in the journal, where articles from North America are increasingly balanced with articles from other, especially European, countries. CONCLUSION: The journal Psychotherapy Research has become an important journal and its development allows thoughts about the future direction of the journal as well as the research field as a whole.

Femtosecond time-delay X-ray holography.

Extremely intense and ultrafast X-ray pulses from free-electron lasers offer unique opportunities to study fundamental aspects of complex transient phenomena in materials. Ultrafast time-resolved methods usually require highly synchronized pulses to initiate a transition and then probe it after a precisely defined time delay. In the X-ray regime, these methods are challenging because they require complex optical systems and diagnostics. Here we propose and apply a simple holographic measurement scheme, inspired by Newton's 'dusty mirror' experiment, to monitor the X-ray-induced explosion of microscopic objects. The sample is placed near an X-ray mirror; after the pulse traverses the sample, triggering the reaction, it is reflected back onto the sample by the mirror to probe this reaction. The delay is encoded in the resulting diffraction pattern to an accuracy of one femtosecond, and the structural change is holographically recorded with high resolution. We apply the technique to monitor the dynamics of polystyrene spheres in intense free-electron-laser pulses, and observe an explosion occurring well after the initial pulse. Our results support the notion that X-ray flash imaging can be used to achieve high resolution, beyond radiation damage limits for biological samples. With upcoming ultrafast X-ray sources we will be able to explore the three-dimensional dynamics of materials at the timescale of atomic motion.

Three-dimensional topological magnetic monopoles and their interactions in a ferromagnetic meta-lattice.

Topological magnetic monopoles (TMMs), also known as hedgehogs or Bloch points, are three-dimensional (3D) non-local spin textures that are robust to thermal and quantum fluctuations due to the topology protection1-4. Although TMMs have been observed in skyrmion lattices1,5, spinor Bose-Einstein condensates6,7, chiral magnets8, vortex rings2,9 and vortex cores10, it has been difficult to directly measure the 3D magnetization vector field of TMMs and probe their interactions at the nanoscale. Here we report the creation of 138 stable TMMs at the specific sites of a ferromagnetic meta-lattice at room temperature. We further develop soft X-ray vector ptycho-tomography to determine the magnetization vector and emergent magnetic field of the TMMs with a 3D spatial resolution of 10 nm. This spatial resolution is comparable to the magnetic exchange length of transition metals11, enabling us to probe monopole-monopole interactions. We find that the TMM and anti-TMM pairs are separated by 18.3 ± 1.6 nm, while the TMM and TMM, and anti-TMM and anti-TMM pairs are stabilized at comparatively longer distances of 36.1 ± 2.4 nm and 43.1 ± 2.0 nm, respectively. We also observe virtual TMMs created by magnetic voids in the meta-lattice. This work demonstrates that ferromagnetic meta-lattices could be used as a platform to create and investigate the interactions and dynamics of TMMs. Furthermore, we expect that soft X-ray vector ptycho-tomography can be broadly applied to quantitatively image 3D vector fields in magnetic and anisotropic materials at the nanoscale.

Redefinition of Fatty Liver Disease from NAFLD to MAFLD through the Lens of Drug Development and Regulatory Science.

Metabolic (dysfunction)-associated fatty liver disease (MAFLD) affects a third of the population and is a leading cause of liver-related death. Since no effective treatments exist, novel approaches to drug development are required. Unfortunately, outdated terminology and definitions of the disease are hampering efforts to develop new drugs and treatments. An international consensus panel has put forth an influential proposal for the disease to be renamed from nonalcoholic fatty liver disease (NAFLD) to MAFLD, including a proposal for how the disease should be diagnosed. As allies with the many stakeholders in MAFLD care-including patients, patients' advocates, clinicians, researchers, nurse and allied health groups, regional societies, and others-we are aware of the negative consequences of the NAFLD term and definition. We share the sense of urgency for change and will act in new ways to achieve our goals. Although there is much work to be done to overcome clinical inertia and reverse worrisome recent trends, the MAFLD initiative provides a firm foundation to build on. It provides a roadmap for moving forward toward more efficient care and affordable, sustainable drug and device innovation in MAFLD care. We hope it will bring promising new opportunities for a brighter future for MAFLD care and improve care and outcomes for patients of one of the globe's largest and costliest public health burdens. From this viewpoint, we have revisited this initiative through the perspectives of drug development and regulatory science.

Scattering of evanescent electromagnetic waves by a cylinder near the flat boundary: the Green function and fast numerical method.

The scattering of plane evanescent waves by a cylinder is studied. The Green function for the Helmholtz equation for two dielectrics with flat interface is found and applied for the numerical calculation of the scattered field by the boundary elements method. The Green function keeps close track of scattering, including multiple reflections. The result may be applicable for the data analysis in near-field optical microscopy.

Relationship between mental states in depression: the assimilation model perspective.

Metacognitive theories describe relationships between mental-affective self-states, including the capacity of one self-state to reflect upon another self-state. The assimilation model is a metacognitive approach that understands self-states as made of traces of experiences at different levels of integration. Psychological problems are understood as impaired accessibility of certain self-states to the person's normal awareness. These states are distressing or otherwise subjectively problematic when they emerge. This exploratory study used the assimilation framework to describe mental states in 17 clients who participated in a clinical trial of cognitive-behavioral therapy for depression. Three clinically sophisticated raters examined transcripts of 1h-long psychotherapy session per client to construct qualitative descriptions of self-states and their relationship patterns in these depressed individuals. We then systematically compared and integrated these raters' descriptions of the clients' self-states. In each case, we found a conflict between two internally incompatible states: an interpersonally submissive state and an interpersonally dominant one, a pattern consistent with the model's theoretical description of depression.

Differential electron yield imaging with STXM.

Total electron yield (TEY) imaging is an established scanning transmission X-ray microscopy (STXM) technique that gives varying contrast based on a sample's geometry, elemental composition, and electrical conductivity. However, the TEY-STXM signal is determined solely by the electrons that the beam ejects from the sample. A related technique, X-ray beam-induced current (XBIC) imaging, is sensitive to electrons and holes independently, but requires electric fields in the sample. Here we report that multi-electrode devices can be wired to produce differential electron yield (DEY) contrast, which is also independently sensitive to electrons and holes, but does not require an electric field. Depending on whether the region illuminated by the focused STXM beam is better connected to one electrode or another, the DEY-STXM contrast changes sign. DEY-STXM images thus provide a vivid map of a device's connectivity landscape, which can be key to understanding device function and failure. To demonstrate an application in the area of failure analysis, we image a 100 nm, lithographically-defined aluminum nanowire that has failed after being stressed with a large current density.

An ultrahigh-resolution soft x-ray microscope for quantitative analysis of chemically heterogeneous nanomaterials.

The analysis of chemical states and morphology in nanomaterials is central to many areas of science. We address this need with an ultrahigh-resolution scanning transmission soft x-ray microscope. Our instrument provides multiple analysis tools in a compact assembly and can achieve few-nanometer spatial resolution and high chemical sensitivity via x-ray ptychography and conventional scanning microscopy. A novel scanning mechanism, coupled to advanced x-ray detectors, a high-brightness x-ray source, and high-performance computing for analysis provide a revolutionary step forward in terms of imaging speed and resolution. We present x-ray microscopy with 8-nm full-period spatial resolution and use this capability in conjunction with operando sample environments and cryogenic imaging, which are now routinely available. Our multimodal approach will find wide use across many fields of science and facilitate correlative analysis of materials with other types of probes.

Probing the Location and Speciation of Elements in Zeolites with Correlated Atom Probe Tomography and Scanning Transmission X-Ray Microscopy.

Characterizing materials at nanoscale resolution to provide new insights into structure property performance relationships continues to be a challenging research target due to the inherently low signal from small sample volumes, and is even more difficult for nonconductive materials, such as zeolites. Herein, we present the characterization of a single Cu-exchanged zeolite crystal, namely Cu-SSZ-13, used for NOX reduction in automotive emissions, that was subject to a simulated 135,000-mile aging. By correlating Atom Probe Tomography (APT), a single atom microscopy method, and Scanning Transmission X-ray Microscopy (STXM), which produces high spatial resolution X-ray Absorption Near Edge Spectroscopy (XANES) maps, we show that a spatially non-uniform proportion of the Al was removed from the zeolite framework. The techniques reveal that this degradation is heterogeneous at length scales from micrometers to tens of nanometers, providing complementary insight into the long-term deactivation of this catalyst system.

Report on a project on three-dimensional imaging of the biological cell by single-particle X-ray diffraction. Addendum.

In the paper by Sayre [Acta Cryst. (2008), A64, 33-35], a proposal is made to use stereoscopy as a short-term means of overcoming the primarily technological hurdles involved in three-dimensional imaging of the biological cell by soft X-ray diffraction microscopy. This addendum provides a broader perspective on the techniques used by this rapidly maturing community to investigate structural problems in the biological and material sciences.