Stability Limits and Defect Dynamics in Ag Nanoparticles Probed by Bragg Coherent Diffractive Imaging.

Dissolution is critical to nanomaterial stability, especially for partially dealloyed nanoparticle catalysts. Unfortunately, highly active catalysts are often not stable in their reactive environments, preventing widespread application. Thus, focusing on the structure-stability relationship at the nanoscale is crucial and will likely play an important role in meeting grand challenges. Recent advances in imaging capability have come from electron, X-ray, and other techniques but tend to be limited to specific sample environments and/or two-dimensional images. Here, we report investigations into the defect-stability relationship of silver nanoparticles to voltage-induced electrochemical dissolution imaged in situ in three-dimensional detail by Bragg coherent diffractive imaging. We first determine the average dissolution kinetics by stationary probe rotating disk electrode in combination with inductively coupled plasma mass spectrometry, which allows in situ measurement of Ag+ ion formation. We then observe the dissolution and redeposition processes in single nanocrystals, providing unique insight about the role of surface strain, defects, and their coupling to the dissolution chemistry. The methods developed and the knowledge gained go well beyond a "simple" silver electrochemistry and are applicable to all electrocatalytic reactions where functional links between activity and stability are controlled by structure and defect dynamics.

Three Dimensional Variable-Wavelength X-Ray Bragg Coherent Diffraction Imaging.

We present and demonstrate a formalism by which three-dimensional (3D) Bragg x-ray coherent diffraction imaging (BCDI) can be implemented without moving the sample by scanning the energy of the incident x-ray beam. This capability is made possible by introducing a 3D Fourier transform that accounts for x-ray wavelength variability. We demonstrate the approach by inverting coherent Bragg diffraction patterns from a gold nanocrystal measured with an x-ray energy scan. Variable-wavelength BCDI will expand the breadth of feasible in situ 3D strain imaging experiments towards more diverse materials environments, especially where sample manipulation is difficult.

Development of an in situ temperature stage for synchrotron X-ray spectromicroscopy.

In situ characterization of micro- and nanoscale defects in polycrystalline thin-film materials is required to elucidate the physics governing defect formation and evolution during photovoltaic device fabrication and operation. X-ray fluorescence spectromicroscopy is particularly well-suited to study defects in compound semiconductors, as it has a large information depth appropriate to study thick and complex materials, is sensitive to trace amounts of atomic species, and provides quantitative elemental information, non-destructively. Current in situ methods using this technique typically require extensive sample preparation. In this work, we design and build an in situ temperature stage to study defect kinetics in thin-film solar cells under actual processing conditions, requiring minimal sample preparation. Careful selection of construction materials also enables controlled non-oxidizing atmospheres inside the sample chamber such as H2Se and H2S. Temperature ramp rates of up to 300 °C/min are achieved, with a maximum sample temperature of 600 °C. As a case study, we use the stage for synchrotron X-ray fluorescence spectromicroscopy of CuIn(x)Ga(1-x)Se2 (CIGS) thin-films and demonstrate predictable sample thermal drift for temperatures 25-400 °C, allowing features on the order of the resolution of the measurement technique (125 nm) to be tracked while heating. The stage enables previously unattainable in situ studies of nanoscale defect kinetics under industrially relevant processing conditions, allowing a deeper understanding of the relationship between material processing parameters, materials properties, and device performance.

BATTERIES. Topological defect dynamics in operando battery nanoparticles.

Topological defects can markedly alter nanomaterial properties. This presents opportunities for "defect engineering," where desired functionalities are generated through defect manipulation. However, imaging defects in working devices with nanoscale resolution remains elusive. We report three-dimensional imaging of dislocation dynamics in individual battery cathode nanoparticles under operando conditions using Bragg coherent diffractive imaging. Dislocations are static at room temperature and mobile during charge transport. During the structural phase transformation, the lithium-rich phase nucleates near the dislocation and spreads inhomogeneously. The dislocation field is a local probe of elastic properties, and we find that a region of the material exhibits a negative Poisson's ratio at high voltage. Operando dislocation imaging thus opens a powerful avenue for facilitating improvement and rational design of nanostructured materials.

Coherent Bragg nanodiffraction at the hard X-ray Nanoprobe beamline.

Bragg coherent diffraction with nanofocused hard X-ray beams provides unique opportunities for quantitative in situ studies of crystalline structure in nanoscale regions of complex materials and devices by a variety of diffraction-based techniques. In the case of coherent diffraction imaging, a major experimental challenge in using nanoscale coherent beams is maintaining a constant scattering volume such that coherent fringe visibility is maximized and maintained over the course of an exposure lasting several seconds. Here, we present coherent Bragg diffraction patterns measured from different nanostructured thin films at the Sector 26 Nanoprobe beamline at the Advanced Photon Source and demonstrate that with nanoscale positional control, coherent diffraction patterns can be measured with source-limited fringe visibilities more than 50% suitable for imaging by coherent Bragg ptychography techniques.

The Bionanoprobe: hard X-ray fluorescence nanoprobe with cryogenic capabilities.

Hard X-ray fluorescence microscopy is one of the most sensitive techniques for performing trace elemental analysis of biological samples such as whole cells and tissues. Conventional sample preparation methods usually involve dehydration, which removes cellular water and may consequently cause structural collapse, or invasive processes such as embedding. Radiation-induced artifacts may also become an issue, particularly as the spatial resolution increases beyond the sub-micrometer scale. To allow imaging under hydrated conditions, close to the `natural state', as well as to reduce structural radiation damage, the Bionanoprobe (BNP) has been developed, a hard X-ray fluorescence nanoprobe with cryogenic sample environment and cryo transfer capabilities, dedicated to studying trace elements in frozen-hydrated biological systems. The BNP is installed at an undulator beamline at sector 21 of the Advanced Photon Source. It provides a spatial resolution of 30 nm for two-dimensional fluorescence imaging. In this first demonstration the instrument design and motion control principles are described, the instrument performance is quantified, and the first results obtained with the BNP on frozen-hydrated whole cells are reported.

Performance and characterization of the prototype nm-scale spatial resolution scanning multilayer Laue lenses microscope.

Synchrotron based x-ray microscopy established itself as a prominent tool for noninvasive investigations in many areas of science and technology. Many facilities around the world routinely achieve sub-micrometer resolution with a few instruments capable of imaging with the spatial resolution better than 100 nm. With an ongoing effort to push the 2D/3D resolution down to 10 nm in the hard x-ray regime both fabrication of the nano-focusing optics and stability of a microscope become extremely challenging. In this work we present our approach to overcome technical challenges on the path towards high spatial resolution hard x-ray microscopy and demonstrate the performance of a scanning fluorescence microscope equipped with the multilayer Laue lenses focusing optics.

The association between course of illness and subsequent morbidity in bipolar I disorder.

OBJECTIVE: We examined the relationship between certain bipolar I disorder clinical course variables over 5 years with outcome over the subsequent 5-year period. METHODS: Prospective observational follow-up data of 123 bipolar I subjects were analyzed. Predictive clinical variables included the frequency and direction of switches, and the quantity, polarity and length of affective periods. Outcome variables were an affective burden index (ABI) accounting for week-by-week severity and weeks hospitalized. Bivariate analyses guided the selection of predictors for multivariable analyses against the outcome variables. RESULTS: Affective burden index: while the number and direction of switches, the number of polyphasic episodes, weeks in hypomania/mania/mixed state, weeks in minor/major depression, weeks in at least marked affective syndrome, and weeks in any affective syndrome all had bivariate correlation (p<0.01) with the ABI, only weeks in hypomania/mania/mixed state and weeks in minor/major depression made significant contributions in the multivariable analysis (p<0.01) with the ABI. Weeks hospitalized: weeks in at least marked affective syndrome were significantly correlated with weeks hospitalized in bivariate analysis (p<0.01), and maintained a contribution to weeks hospitalized in the multivariable analysis (p<0.01). CONCLUSIONS: The quantity and severity of weeks in symptomatic affective states are possibly greater predictors of affective burden in bipolar I patients than the quantity and direction of affective switches.

Nanometer linear focusing of hard x rays by a multilayer Laue lens.

We report on a type of linear zone plate for nanometer-scale focusing of hard x rays, a multilayer Laue lens (MLL), produced by sectioning a multilayer and illuminating it in Laue diffraction geometry. Because of its large optical depth, a MLL spans the diffraction regimes applicable to a thin Fresnel zone plate and a crystal. Coupled wave theory calculations indicate that focusing to 5 nm or smaller with high efficiency should be possible. Partial MLL structures with outermost zone widths as small as 10 nm have been fabricated and tested with 19.5 keV synchrotron radiation. Focal sizes as small as 30 nm with efficiencies up to 44% are measured.

Quality of life in rheumatoid arthritis: impact of disability and lifetime depressive spectrum symptomatology.

OBJECTIVE: The aim of this study was to investigate the impact of disability and lifetime subthreshold depressive symptoms on Health-Related Quality of Life (HRQoL) among patients with rheumatoid arthritis (RA). METHODS: Ninety-two subjects with a diagnosis of RA according to the American College of Rheumatology (ACR) criteria were recruited at the Department of Rheumatology of the University Hospital, Pisa, Italy. Participants who met DSM-IV-TR diagnostic criteria for current or previous Axis I disorders were excluded. Assessments of functional status and disability was conducted using both the ACR classification and the Stanford Health Assessment Questionnaire (HAQ). Health-related Quality of Life was assessed using the Medical Outcomes Study Short Form 36 health survey questionnaire (MOS-SF36) and lifetime depressive spectrum symptomatology using the Mood Spectrum Questionnaire, Self-Report version (MOODS-SR). RESULTS: Comparison with MOS-SF36 Italian normative values indicated that RA patients were significantly impaired on mental and physical HRQoL areas. Correlations between MOODS-SR depressive scores and ACR severity (Spearman rho = 0.15, p = 0.07) and HAQ score (Spearman rho = 0.20, p = 0.05) were modest in absolute value and borderline significant. Lifetime mood depressive spectrum was related with impaired HRQoL levels, both in physical (except for bodily pain) and mental (except for social functioning) domains. Associations of mood depressive spectrum and general health, vitality, role emotional and mental health continued to be significant after controlling for functional status, duration of illness, age and gender. CONCLUSIONS: Because lifetime mood depressive symptoms significantly contribute to impairment in HRQoL in RA patients without a past psychiatric history, even after controlling for functional status, duration of illness and demographic characteristics, these symptoms should be assessed for an accurate clinical evaluation and appropriate clinical management of RA patients.

Acceptability, validity and reliability of the Structured Clinical Interview for the Spectrum of Substance Use (SCI-SUBS): a pilot study.

This paper reports on the acceptability, reliability and validity of the Structured Clinical Interview for the Spectrum of Substance Use (SCI-SUBS), a new instrument exploring the interactive pathway between substance abuse and psychiatric disorders. Psychiatric outpatients with (n = 21) and without (n = 32) substance abuse comorbidity according to the DSM-IV, non-psychiatric subjects with opioid dependence (OD, n = 14) and normal controls (n = 33) were assessed with the SCI-SUBS. The presence or absence of psychiatric disorders was determined with the Structured Clinical Interview for DSM IV (SCID). The SCI-SUBS was well accepted by participants. The internal consistency of the domains was satisfactory (between 0.64 and 0.93). Domain scores of OD subjects were significantly higher than those of controls and of psychiatric patients without substance abuse. The cut-off point on the SCI-SUBS total score at which there was optimal discrimination between the presence and the absence of a DSM-IV diagnosis of substance abuse was 45. The pilot version of the SCI-SUBS has satisfactory internal consistency and construct validity.

Panic-agoraphobic spectrum: reliability and validity of assessment instruments.

DSM IV is a simple, reliable diagnostic system with many advantages. However, DSM diagnostic criteria may not provide sufficient characterization of clinically significant symptoms. We have undertaken a project to assess an array (spectrum) of clinical features associated with different DSM Disorders. The purpose of this paper is to report on reliability of assessment instruments for Panic-Agoraphobic Spectrum (PAS), to document convergent validity of PAS symptom groupings, and to confirm the relationship between PAS and DSM IV Panic Disorder (PD). We studied 22 normal controls and 95 outpatients who met criteria for Panic Disorder with and without lifetime Major Depression, and Major Depression or Obsessive Compulsive Disorder without lifetime Panic Disorder. Assessment instruments had excellent reliability and there was good concordance between interview and self-report formats. PAS scores were highest in subjects with PD, followed by outpatients without PD, and were lowest in normal controls. PAS scores varied among PD patients, and a subgroup of patients without PD scored high on PAS. We conclude that PAS can be reliably assessed, and that it describes a valid, coherent constellation of features associated with DSM IV Panic Disorder, but providing additional important clinical information.

Does incomplete recovery from first lifetime major depressive episode herald a chronic course of illness?

OBJECTIVE: This study investigated the influence of incomplete recovery from first lifetime major depressive episodes on long-term outcome. METHOD: After their first lifetime major depressive episode, patients were divided into asymptomatic (N=70) and residual subthreshold depressive symptom (N=26) recovery groups and compared on longitudinal course during up to 12 years of prospective naturalistic follow-up. RESULTS: Patients with residual subthreshold depressive symptoms during recovery had significantly more severe and chronic future courses. Those with residual symptoms relapsed to major and minor depressive episodes faster and had more recurrences, shorter well intervals, and fewer symptom-free weeks during follow-up than asymptomatic patients. CONCLUSIONS: Resolution of major depressive episodes with residual subthreshold depressive symptoms, even the first lifetime episode, appears to be the first step of a more severe, relapsing, and chronic future course. When ongoing subthreshold symptoms continue after major depressive episodes, the illness is still active, and continued treatment is strongly recommended.

Influence of panic-agoraphobic spectrum symptoms on treatment response in patients with recurrent major depression.

OBJECTIVE: The authors tested the hypothesis that a lifetime history of panic-agoraphobic spectrum symptoms predicts a poorer response to depression treatment. METHOD: A threshold for clinically meaningful panic-agoraphobic spectrum symptoms was defined by means of receiver operating characteristic curve analysis of total scores on the Structured Clinical Interview for Panic-Agoraphobic Spectrum in a group of 88 outpatients with and without panic disorder. This threshold was then applied to a group of 61 women with recurrent major depression, who completed a self-report version of the same instrument, in order to compare treatment outcomes for patients above and below this clinical threshold. RESULTS: Women with high scores (> or =35) on the Panic-Agoraphobic Spectrum Self-Report were less likely than women with low scores (<35) to respond to interpersonal psychotherapy alone (43.5% versus 68.4%, respectively). Women with high scores also took longer (18.1 versus 10.3 weeks) to respond to a sequential treatment paradigm (adding a selective serotonin reuptake inhibitor when depression did not remit with interpersonal psychotherapy alone). This effect was only partially accounted for by the higher likelihood that patients with high scores required the addition of antidepressants. Although four domains from the Panic-Agoraphobic Spectrum Self-Report were individually associated with a longer time to remission, only stress sensitivity emerged as significant in multivariate regression analyses. CONCLUSIONS: A lifetime burden of panic-agoraphobic spectrum symptoms predicted a poorer response to interpersonal psychotherapy and an 8-week delay in sequential treatment response among women with recurrent depression. These results lend clinical validity to the spectrum construct and highlight the need for alternate psychotherapeutic and pharmacologic strategies to treat depressed patients with panic spectrum features.

Psychosocial disability during the long-term course of unipolar major depressive disorder.

BACKGROUND: The goal of this study was to investigate psychosocial disability in relation to depressive symptom severity during the long-term course of unipolar major depressive disorder (MDD). METHODS: Monthly ratings of impairment in major life functions and social relationships were obtained during an average of 10 years' systematic follow-up of 371 patients with unipolar MDD in the National Institute of Mental Health Collaborative Depression Study. Random regression models were used to examine variations in psychosocial functioning associated with 3 levels of depressive symptom severity and the asymptomatic status. RESULTS: A progressive gradient of psychosocial impairment was associated with a parallel gradient in the level of depressive symptom severity, which ranges from asymptomatic to subthreshold depressive symptoms to symptoms at the minor depression/dysthymia level to symptoms at the MDD level. Significant increases in disability occurred with each stepwise increment in depressive symptom severity. CONCLUSIONS: During the long-term course, disability is pervasive and chronic but disappears when patients become asymptomatic. Depressive symptoms at levels of subthreshold depressive symptoms, minor depression/ dysthymia, and MDD represent a continuum of depressive symptom severity in unipolar MDD, each level of which is associated with a significant stepwise increment in psychosocial disability.

Multiple recurrences of major depressive disorder.

OBJECTIVE: The authors of this study examined multiple recurrences of unipolar major depressive disorder. METHOD: A total of 318 subjects with unipolar major depressive disorder were prospectively followed for 10 years within a multicenter naturalistic study. Survival analytic techniques were used to examine the probability of recurrence after recovery from the index episode. RESULTS: The mean number of episodes of major depression per year of follow-up was 0. 21, and nearly two-thirds of the subjects suffered at least one recurrence. The number of lifetime episodes of major depression was significantly associated with the probability of recurrence, such that the risk of recurrence increased by 16% with each successive recurrence. The risk of recurrence progressively decreased as the duration of recovery increased. Within subjects, there was very little consistency in the time to recurrence. CONCLUSIONS: Major depressive disorder is a highly recurrent illness. The risk of the recurrence of major depressive disorder progressively increases with each successive episode and decreases as the duration of recovery increases.