Electrodeposited MoxSyOz/Ni Tribological Coatings.

Deposition of molybdenum disulfide (MoS2) coatings using physical vapor deposition (PVD) and mechanical burnishing has been widely assessed for solid lubricants in space applications but still suffers from line-of-sight constraints on complex geometries. Here, we highlight one of the first demonstrations of electrodeposited MoxSyOz and MoxSyOz/Ni thin-film coatings from aqueous solutions of ammonium tetrathiomolybdate for solid lubricant applications and their remarkable ability to provide low coefficients of friction and high wear resistance. Characterization of the coating morphology shows amorphous microstructures with a high oxygen content and cracking upon drying. Even so, electrodeposited MoxSyOz can achieve low steady-state coefficients of friction (µ ∼ 0.05-0.06) and wear rates (2.6 × 10-7 mm3/(N m)) approaching those of physical vapor deposited coatings (2.3 × 10-7 mm3/(N m)). Additionally, we show that adding dopants such as nickel increased the wear rate (7.5 × 10-7 mm3/(N m)) and initial coefficient of friction (µi = 0.23) due to compositional modifications such as dramatic sub-stoichiometry (S/Mo ∼ 1) and expression of a NiOx surface layer, although doping did reduce the degree of cracking upon drying.

Water adsorption on MoS2 under realistic atmosphere conditions and impacts on tribology.

Molybdenum disulfide (MoS2) is a 2D material widely used as a dry lubricant. However, exposure to water and oxygen is known to reduce its effectiveness, and therefore an understanding of the uptake of water is important information for mitigating these effects. Here we use grand canonical Monte Carlo simulations to rigorously study water adsorption on MoS2 surfaces and edges with different concentrations of defects under realistic atmospheric conditions (i.e. various temperatures and humidity levels). We find that the amount of water adsorbed depends strongly on the number of defects. Simulations indicate that defect sites are generally saturated with water even at low ppm levels of humidity. Water binds strongly to S vacancies on interlamellar surfaces, but generally only one water molecule can fit on each of these sites. Defects on surfaces or edges of lamellae also strongly attract water molecules that then nucleate small clusters of water bonded via hydrogen bonding. We demonstrate that water preferentially binds to surface defects, but once those are saturated at a critical humidity level of about 500-1000 ppm water, water binds to edge sites where it negatively impacts the tribological performance of MoS2.

Feasibility, acceptability, and depression outcomes of a randomized controlled trial of Mindful Self-Compassion for Teens (MSC-T) for adolescents with subsyndromal depression.

INTRODUCTION: Adolescents are experiencing high rates of depressive symptoms, with negative consequences to their long-term health. Group-based, mindful self-compassion programs show promise in mitigating the development of more significant depression in at-risk adolescents. However, the lack of well-designed, active control conditions has limited the ability to examine the efficacy of such interventions. METHODS: Fifty-nine adolescents (Mage = 15.81, 70% female) with subsyndromal depressive symptoms from the Southeastern US were randomized to group-based Mindful Self-Compassion for Teens (N = 30) or a newly developed active control Healthy Lifestyles group (N = 29) during 2018 and 2019. Participants attended 8 weekly "main" sessions followed by 6 monthly continuation sessions. The feasibility and acceptability of participation in both groups were measured using attrition, attendance, credibility, and satisfaction data. Depression scores were collected weekly, and self-compassion scores were collected five times across 36 weeks. RESULTS: Both groups were equally feasible and acceptable during the 8-week program period; however, monthly continuation sessions were poorly attended in both groups. The risk of developing clinically significant depression was 2.6 times higher in the control group compared with the self-compassion group (p = .037) across 36 weeks. Depression significantly decreased in the self-compassion group, while it significantly increased in the control group. Both groups increased significantly in reports of self-compassion. These findings are on par with results noting the efficacy of cognitive-based interventions for high-risk adolescents; follow-up studies with larger sample sizes should be conducted to confirm these findings. CONCLUSIONS: Initial examination suggests Mindful Self-Compassion for Teens programming is feasible, acceptable, and efficacious in preventing the development of clinically significant depression in adolescents with subsyndromal depression. Future studies may benefit from refinements to the self-compassion measurement and/or the attention control condition; moreover, larger sample sizes are needed to confirm results.

Is everything really okay?: Using ecological momentary assessment to evaluate daily co-fluctuations in anxiety and reassurance seeking.

OBJECTIVE: Reassurance seeking, a behavior prominent in anxiety disorders and depression, is associated with poorer quality of interpersonal relationships and acts as a mechanism of stress generation. However, little research has elucidated momentary associations between state anxiety and reassurance seeking behaviors. METHOD: In a sample of 104 university-affiliated young adults, we sought to replicate cross-sectional associations of reassurance seeking with trait anxiety (Aim 1) and intolerance of uncertainty (Aim 2). We then used ecological momentary assessment (EMA) to evaluate concurrent fluctuations in daily anxiety and reassurance seeking across 14 consecutive days (Aim 3). Hierarchical multi-level models for intensive longitudinal data were used to evaluate the relationship between state anxiety and daily reassurance seeking. RESULTS: In baseline analyses, trait anxiety and intolerance of uncertainty were significantly associated with greater trait reassurance seeking, controlling for depression. Analyses of the EMA data showed that daily reassurance seeking behaviors fluctuated concurrently with daily anxiety during the 14 days, while controlling for trait anxiety and depression. CONCLUSION: Given evidence of concurrent fluctuations between state anxiety and reassurance seeking, the behavior should be considered as a potential target in treatment for anxiety disorders.

Spectroscopic Evaluation of Surface Chemical Processes Occurring in MoS2 upon Aging.

Molybdenum disulfide (MoS2) coatings have attracted widespread industrial interest owing to their excellent lubricating properties under vacuum and inert conditions. Unfortunately, the increase in MoS2 interfacial shear strength following prolonged exposure to ambient conditions (a process referred to as "aging") has resulted in reliability issues when MoS2 is employed as solid lubricant. While aging of MoS2 is generally attributed to physical and chemical changes caused by adsorbed water and/or oxygen, a mechanistic understanding of the relative role of these two gaseous species in the evolution of the surface chemistry of MoS2 is still elusive. Additionally, remarkably little is known about the effect of thermally- and tribologically-induced microstructural variations in MoS2 on the aging processes occurring in the near-surface region of the coating. Here, we employed three analytical techniques, namely, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and grazing-incidence X-ray diffraction (GIXRD), to gain insights into the aging phenomena occurring in sputtered MoS2 coatings before and after tribological testing, while also evaluating the impact of thermally-induced variations in the coating structure on aging. The outcomes of XPS analyses provide evidence that a substantial surface oxidation of MoS2 only takes place under humid conditions. Furthermore, the correlation of XPS, ToF-SIMS, and GIXRD results allowed for the development of a qualitative model for the impact of shear-induced microstructural variations in MoS2 on the transport of water in the near-surface region of this material and on the extent of surface oxidation. These results add significantly to our understanding of the aging mechanisms of MoS2 coatings used in tribological applications and their dependence on environmental conditions.

High-Sensitivity Low-Energy Ion Spectroscopy with Sub-Nanometer Depth Resolution Reveals Oxidation Resistance of MoS2 Increases with Film Density and Shear-Induced Nanostructural Modifications of the Surface.

For decades, density has been attributed as a critical aspect of the structure of sputter-deposited nanocrystalline molybdenum disulfide (MoS2) coatings impacting oxidation resistance and wear resistance. Despite its importance, there are few examples in the literature that explicitly investigate the relationship between the density and oxidation behaviors of MoS2 coatings. Aging and oxidation are primary considerations for the use of MoS2 coatings in aerospace applications as they inevitably experience prolonged storage in water and oxygen-rich environments prior to use. Oxidation that is either limited to the first few nanometers or through the bulk of the coating can result in seizure due to high initial coefficients of friction or component failure from excessive wear. High-sensitivity low-energy ion spectroscopy (HS-LEIS) and Rutherford backscattering spectrometry (RBS) are both used to understand the extent of oxidation throughout the first ∼10 nanometers of the surface of pure sputtered nanocrystalline MoS2 coatings after high-temperature aging and how it is impacted by the density of coatings as measured by RBS. Results show that low-density coatings (ρ = 3.55 g/cm3) exhibit a more columnar microstructure and voiding, which act as pathways for oxidative species to penetrate and interact with edge sites, causing severe surface and subsurface oxidation. Furthermore, HS-LEIS of surfaces sheared prior to oxidation reveals that the oxidation resistance of low-density MoS2 coatings can be significantly improved by shear-induced reorientation of the surface microstructure to a basal orientation and elimination of pathways for oxygen into the bulk through compaction of surface and subsurface voids.

Role of Environment on the Shear-Induced Structural Evolution of MoS2 and Impact on Oxidation and Tribological Properties for Space Applications.

This work investigates the role of water and oxygen on the shear-induced structural modifications of molybdenum disulfide (MoS2) coatings for space applications and the impact on friction due to oxidation from aging. We observed from transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) that sliding in both an inert environment (i.e., dry N2) or humid lab air forms basally oriented (002) running films of varying thickness and structure. Tribological testing of the basally oriented surfaces created in dry N2 and air showed lower initial friction than a coating with an amorphous or nanocrystalline microstructure. Aging of coatings with basally oriented surfaces was performed by heating samples at 250 °C for 24 h. Post aging tribological testing of the as-deposited coating showed increased initial friction and a longer transition from higher friction to lower friction (i.e., run-in) due to oxidation of the surface. Tribological testing of raster patches formed in dry N2 and air both showed an improved resistance to oxidation and reduced initial friction after aging. The results from this study have implications for the use of MoS2-coated mechanisms in aerospace and space applications and highlight the importance of preflight testing. Preflight cycling of components in inert or air environments provides an oriented surface microstructure with fewer interaction sites for oxidation and a lower shear strength, reducing the initial friction coefficient and oxidation due to aging or exposure to reactive species (i.e., atomic oxygen).

Adaptive Treatment for Youth With Substance Use and Depression: Early Depression Response and Short-term Outcomes.

OBJECTIVE: To investigate prevalence and predictors of early depression response (EDR) in adolescents with substance use and depression receiving cognitive-behavioral therapy (CBT) for substance use and to test the efficacy of supplemental CBT targeting depression (CBT-D) for non-EDR adolescents in an adaptive treatment approach. METHOD: At 2 sites, 95 youths (ages 14-21, mean [SD] = 17.4 [1.8]) with alcohol or cannabis use and depressive symptoms received up to 12 sessions of CBT for substance use over 14 weeks. Assessments were at baseline and weeks 4, 9, and 14. The Children's Depression Rating Scale-Revised was the primary depression measure, with a reduction of 50% or more on this scale at week 4 defining EDR. The primary substance use outcomes of alcohol use, heavy alcohol use, and cannabis use frequency were assessed via interview report on the Alcohol Consumption Questionnaire and the Drug Checklist. Urinalysis provided a secondary measure of cannabis use. Non-EDR adolescents were randomly assigned to supplemental CBT-D or enhanced treatment as usual (ETAU). RESULTS: Thirty-five adolescents (37%; 95% CI, 27%-47%) demonstrated EDR. Fewer days of cannabis use (odds ratio 0.977; 95% CI, 0.961-0.992) and absence of conduct disorder (odds ratio 0.149; 95% CI, 0.031-0.716) predicted EDR. Frequency of drinking (F1,82 = 11.09, η2 = 0.119, p = .001), heavy drinking (F1,82 = 19.91, η2 = 0.195, p < .0001), and cannabis use (F1,220 = 35.01, η2 = 0.137, p < .001) decreased over time for EDR, CBT-D, and ETAU adolescents, with EDR adolescents evidencing earlier lower cannabis use (F2,220 = 4.16, η2 = 0.036, p = .0169). Negative (clean) urine screens increased over time (F1,219 = 5.10, η2 = 0.023, p = .0249). Comparison of CBT-D and ETAU indicated that depression significantly decreased over time in both groups (F1,48 = 64.20, η2 = 0.572, p < .001), with no advantage for CBT-D. CONCLUSION: Approximately one-third of adolescents with substance use and depression attain EDR during substance use treatment. Less frequent cannabis use facilitates depression response. The relatively small sample may have precluded identification of additional EDR predictors. CLINICAL TRIAL REGISTRATION INFORMATION: Treatment for Teens With Alcohol Abuse and Depression; https://clinicaltrials.gov/; NCT02227589.

Hopelessness and depressive symptoms in children and adolescents: An integrative data analysis.

Although hopelessness has been linked to depression for centuries, the diagnostic criteria for depression are inconsistent with regard to the status of hopelessness. Most research on hopelessness and depression has focused on adults. The current study examined this relation in children and adolescents. Integrative data analyses with a pooled sample (N = 2466) showed that clinical levels of hopelessness multiplied the odds of having a clinical diagnosis of depression 10-fold. Conversely, not having clinical levels of hopelessness multiplied the odds of endorsing no clinical level of depressive symptoms 28-fold. Moreover, results differed by levels of depression: (a) among youths with clinical levels of depression, hopelessness was associated with six depressive symptoms; (b) among youths without clinical levels of depression, hopelessness was associated with nine depressive symptoms. We found that hopelessness helps to explain the heterogeneity of depressive presentations. Our finding supports the consideration of hopelessness in the diagnosis (if not treatment and prevention) of depression in children and adolescents. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Feasibility of an Integrated Treatment Approach for Youth with Depression, Suicide Attempts, and Substance Use Problems.

Depression, suicidal behaviors and substance use problems frequently co-occur, and treatment for youth with these co-occurring problems is often fragmented and challenging. An integrated cognitive-behavioral treatment approach that builds upon a relapse prevention framework and applies common core skills, language, and approach for treating these related problems may be clinically beneficial. Following a description of the integrated approach, we present results of a pilot trial (n = 13) to examine the acceptability and feasibility of the Cognitive-Behavioral Therapy - Relapse Prevention (CBT-RP) intervention plus enhanced treatment as usual (TAU) compared to enhanced TAU alone. The feasibility of the CBT-RP + TAU intervention was reflected by high rates of retention (86%). The acceptability was reflected in positive evaluations regarding the helpfulness of the intervention by adolescents and families. The majority of youth in both CBT-RP + TAU and TAU alone groups evidenced reductions in depression and suicide ideation from study entry to Week 20. Patterns of reduction were more consistent, however, for youth receiving CBT-RP + TAU, and reductions were slower to emerge for some youth receiving TAU alone. Reductions in alcohol and marijuana problems were similar, but half of the youth in TAU alone (and none in the CBT-RP + TAU group) had emergency department visits related to psychiatric crises or substance related problems. These findings, although based on a small sample, underscore the feasibility and acceptability of an integrated cognitive-behavioral relapse prevention approach for youth with depression, suicide attempt histories, and substance use problems.

Sex differences in predictors of recurrent major depression among current-era military veterans.

Although major depressive disorder (MDD) is a frequent diagnosis among women seeking care in the Veterans Health Administration, little is known about its course. For example, recurrence of MDD and its predictors have been investigated in civilians, but not among female veterans. Because female veterans differ from their civilian counterparts and from male veterans on demographic variables, including race, ethnicity, marital status, and educational level, it is important to identify factors affecting MDD course within this population. We investigated frequency and correlates of recurrent MDD among female veterans and their male counterparts. From a postdeployment research registry of 3,247 participants (660 women and 2,587 men), we selected those with a current episode of MDD (141 women and 462 men). For each sex, we compared those diagnosed with recurrent MDD with those experiencing a single episode on demographics, comorbid diagnoses, family history of mental illness, traumatic experiences, combat exposure, and social support. In contrast to findings in most civilian samples, recurrent MDD was significantly more frequent in female (70.2%) than in male (45.2%) depressed veterans, χ²(1) = 26.96, p < .001. In multivariable analyses, recurrence among women was associated with greater experiences of childhood abuse and more trauma during military service and with lower rates of posttraumatic stress disorder. Among men, recurrence was associated with older age, family history of psychiatric hospitalization, more postmilitary trauma, and lifetime anxiety disorder and with lower likelihood of war zone deployment. Trauma was associated with recurrence in both sexes, but the features of traumatic events differed in women and men. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Moderators of Treatment for Adolescent Depression.

Objective: This brief report reviews the literature on moderators of treatment for adolescent depression. Treatment moderators can help to guide the process of personalizing intervention to individual patient characteristics.Method: We conducted a systematic search in PsycInfo and PubMed. We also reviewed references of previous reviews and searched for moderator analyses conducted secondary to published efficacy studies.Results: We review 27 studies that address the following categories of moderators: demographics, severity indices, comorbidity, contextual factors, history of abuse or trauma, and cognition and coping. We found limited evidence that demographic, contextual, or cognitive variables consistently moderated treatment for adolescent depression. There was some indication of moderation by race/ethnicity, presence of some comorbid disorders, greater depression severity, and a history of trauma.Conclusion: Our review found inconsistent findings across studies, likely due to the strong impact of predictors relative to moderators and limited statistical power. More research using innovative statistical approaches is necessary before treatment tailoring can be an empirically-based process.

Formation of Coherent 1H-1T Heterostructures in Single-Layer MoS2 on Au(111).

Heterojunctions of semiconductors and metals are the fundamental building blocks of modern electronics. Coherent heterostructures between dissimilar materials can be achieved by composition, doping, or heteroepitaxy of chemically different elements. Here, we report the formation of coherent single-layer 1H-1T MoS2 heterostructures by mechanical exfoliation on Au(111), which are chemically homogeneous with matched lattices but show electronically distinct semiconducting (1H phase) and metallic (1T phase) character, with the formation of these heterojunctions attributed to a combination of lattice strain and charge transfer. The exfoliation approach employed is free of tape residues usually found in many exfoliation methods and yields single-layer MoS2 with millimeter (mm) size on the Au surface. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning tunneling microscopy (STM), and scanning tunneling spectroscopy (STS) have collectively been employed to elucidate the structural and electronic properties of MoS2 monolayers on Au substrates. Bubbles in the MoS2 formed by the trapping of ambient adsorbates beneath the single layer during deposition, have also been observed and characterized. Our work here provides a basis to produce two-dimensional heterostructures which represent potential candidates for future electronic devices.

Temporal dynamics of the relationship between change in depressive symptoms and cannabis use in adolescents receiving psychosocial treatment for cannabis use disorder.

AIMS: Cannabis use disorder (CUD) and depression frequently co-occur in youth. How depressive symptoms change over the course of CUD treatment and how they impact substance use treatment outcomes is unknown. In the current study, we examine the temporal relationships between cannabis use and depression in adolescents receiving evidence-based treatments for CUD as part of a multisite clinical trial. DESIGN: Six hundred adolescents (age 12-18) with a CUD were randomly assigned to substance use treatment from one of five evidence-based psychosocial interventions. We assessed self-reported cannabis use frequency and depressive symptoms at baseline (BL) and again at 3-, 6-, 9, and 12-months. A bivariate latent change model assessed bidirectional effects of baseline levels and time-lagged changes in depressive symptoms and cannabis use on depression and cannabis use outcomes. FINDINGS: Depressive symptoms (72%) and major depressive disorder (MDD) (18%) were common at BL. Both depression and cannabis use decreased over time and change in cannabis use was significantly associated with change in depressive symptoms (b = 1.22, p = .003). Time-lag analyses showed that within-subject change in depression (from one time point to the next) was predicted by previous depression (b = -0.71, p < .001) but not cannabis use (p = .068), and change (decrease) in cannabis use was predicted by previous (greater) depressive symptoms (b = -1.47, p < .001) but not cannabis use (p = .158), respectively. CONCLUSION: These findings indicate an enduring relationship between decreasing cannabis use and decreasing depression among adolescents lasting for 9-months after receiving psychosocial interventions for CUD. The presence of depressive symptoms did not appear to interfere with substance use treatment or attenuate improvements in cannabis use frequency. A decrease in cannabis use was not contingent upon a reduction in depressive symptoms. These findings are limited by the possibility of regression to the mean for both cannabis use and depressive symptoms, and the lack of a nonintervention control group.

Evidence of Inverse Hall-Petch Behavior and Low Friction and Wear in High Entropy Alloys.

We present evidence of inverse Hall-Petch behavior for a single-phase high entropy alloy (CoCrFeMnNi) in ultra-high vacuum and show that it is associated with low friction coefficients (~0.3). Grain size measurements by STEM validate a recently proposed dynamic amorphization model that accurately predicts grain size-dependent shear strength in the inverse Hall-Petch regime. Wear rates in the initially soft (coarse grained) material were shown to be remarkably low (~10-6 mm3/N-m), the lowest for any HEA tested in an inert environment where oxidation and the formation of mixed metal-oxide films is mitigated. The combined high wear resistance and low friction are linked to the formation of an ultra-nanocrystalline near-surface layer. The dynamic amorphization model was also used to predict an average high angle grain boundary energy (0.87 J/m2). This value was used to explain cavitation-induced nanoporosity found in the highly deformed surface layer, a phenomenon that has been linked to superplasticity.

Comparative efficacy and acceptability of antidepressants, psychotherapies, and their combination for acute treatment of children and adolescents with depressive disorder: a systematic review and network meta-analysis.

BACKGROUND: Depressive disorders are common in children and adolescents. Antidepressants, psychotherapies, and their combination are often used in routine clinical practice; however, available evidence on the comparative efficacy and safety of these interventions is inconclusive. Therefore, we sought to compare and rank all available treatment interventions for the acute treatment of depressive disorders in children and adolescents. METHODS: We did a systematic review and network meta-analysis. We searched PubMed, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, PsycINFO, ProQuest, CINAHL, LiLACS, international trial registries, and the websites of regulatory agencies for published and unpublished randomised controlled trials from database inception until Jan 1, 2019. We included placebo-controlled and head-to-head trials of 16 antidepressants, seven psychotherapies, and five combinations of antidepressant and psychotherapy that are used for the acute treatment of children and adolescents (≤18 years old and of both sexes) with depressive disorder diagnosed according to standard operationalised criteria. Trials recruiting participants with treatment-resistant depression, bipolar disorder, psychotic depression, treatment duration of less than 4 weeks, or an overall sample size of fewer than ten patients were excluded. We extracted data following a predefined hierarchy of outcome measures, and assessed risk of bias and certainty of evidence using validated methods. Primary outcomes were efficacy (change in depressive symptoms) and acceptability (treatment discontinuation due to any cause). We estimated summary standardised mean differences (SMDs) or odds ratios (ORs) with credible intervals (CrIs) using network meta-analysis with random effects. This study was registered with PROSPERO, number CRD42015020841. FINDINGS: From 20 366 publications, we included 71 trials (9510 participants). Depressive disorders in most studies were moderate to severe. In terms of efficacy, fluoxetine plus cognitive behavioural therapy (CBT) was more effective than CBT alone (-0·78, 95% CrI -1·55 to -0·01) and psychodynamic therapy (-1·14, -2·20 to -0·08), but not more effective than fluoxetine alone (-0·22, -0·86 to 0·42). No pharmacotherapy alone was more effective than psychotherapy alone. Only fluoxetine plus CBT and fluoxetine were significantly more effective than pill placebo or psychological controls (SMDs ranged from -1·73 to -0·51); and only interpersonal therapy was more effective than all psychological controls (-1·37 to -0·66). Nortriptyline (SMDs ranged from 1·04 to 2·22) and waiting list (SMDs ranged from 0·67 to 2·08) were less effective than most active interventions. In terms of acceptability, nefazodone and fluoxetine were associated with fewer dropouts than sertraline, imipramine, and desipramine (ORs ranged from 0·17 to 0·50); imipramine was associated with more dropouts than pill placebo, desvenlafaxine, fluoxetine plus CBT, and vilazodone (2·51 to 5·06). Most of the results were rated as "low" to "very low" in terms of confidence of evidence according to Confidence In Network Meta-Analysis. INTERPRETATION: Despite the scarcity of high-quality evidence, fluoxetine (alone or in combination with CBT) seems to be the best choice for the acute treatment of moderate-to-severe depressive disorder in children and adolescents. However, the effects of these interventions might vary between individuals, so patients, carers, and clinicians should carefully balance the risk-benefit profile of efficacy, acceptability, and suicide risk of all active interventions in young patients with depression on a case-by-case basis. FUNDING: National Key Research and Development Program of China.

Depression among military spouses: Demographic, military, and service member psychological health risk factors.

BACKGROUND: More than a decade of war has strained service members and their families and the psychological health of military spouses is a concern. This study uses data from the largest study of military families in the United States to examine the demographic, military-specific, and service member mental health correlates of probable diagnosis of major depressive disorder (MDD) among military spouses. METHODS: Data were from service member-spouse dyads from all branches of the U.S. military. Demographic and military-specific factors were assessed using administrative personnel records and survey data. RESULTS: Of the 9,038 spouses, 4.9% had a probable diagnosis of MDD. In unadjusted models, spouses of service members who deployed and experiencecd combat-related events, were enlisted, had a probable posttraumatic stress disorder (PTSD) diagnosis, or screened positive for alcohol misuse were more likely to screen positive for MDD. In adjusted models, only spouses married to enlisted service members or those with PTSD had increased risk for MDD. Other demographic and military-related factors associated with MDD in spouses included less educational attainment, unemployment, having four or more children, and having prior military service (although not currently serving in the military) in the adjusted models. CONCLUSIONS: Findings characterize demographic, military, and service member psychological health factors that are associated with depression among military spouses. These findings imply that deployment alone may not negatively affect military spouses, but rather it may be the mental health impact on the service member, especially PTSD that increases the odds for MDD among military spouses.

Achieving Ultralow Wear with Stable Nanocrystalline Metals.

Recent work suggests that thermally stable nanocrystallinity in metals is achievable in several binary alloys by modifying grain boundary energies via solute segregation. The remarkable thermal stability of these alloys has been demonstrated in recent reports, with many alloys exhibiting negligible grain growth during prolonged exposure to near-melting temperatures. Pt-Au, a proposed stable alloy consisting of two noble metals, is shown to exhibit extraordinary resistance to wear. Ultralow wear rates, less than a monolayer of material removed per sliding pass, are measured for Pt-Au thin films at a maximum Hertz contact stress of up to 1.1 GPa. This is the first instance of an all-metallic material exhibiting a specific wear rate on the order of 10-9 mm3 N-1 m-1 , comparable to diamond-like carbon (DLC) and sapphire. Remarkably, the wear rate of sapphire and silicon nitride probes used in wear experiments are either higher or comparable to that of the Pt-Au alloy, despite the substantially higher hardness of the ceramic probe materials. High-resolution microscopy shows negligible surface microstructural evolution in the wear tracks after 100k sliding passes. Mitigation of fatigue-driven delamination enables a transition to wear by atomic attrition, a regime previously limited to highly wear-resistant materials such as DLC.

Gas Separation through Bilayer Silica, the Thinnest Possible Silica Membrane.

Membrane-based gas separation processes can address key challenges in energy and environment, but for many applications the permeance and selectivity of bulk membranes is insufficient for economical use. Theory and experiment indicate that permeance and selectivity can be increased by using two-dimensional materials with subnanometer pores as membranes. Motivated by experiments showing selective permeation of H2/CO mixtures through amorphous silica bilayers, here we perform a theoretical study of gas separation through silica bilayers. Using density functional theory calculations, we obtain geometries of crystalline free-standing silica bilayers (comprised of six-membered rings), as well as the seven-, eight-, and nine-membered rings that are observed in glassy silica bilayers, which arise due to Stone-Wales defects and vacancies. We then compute the potential energy barriers for gas passage through these various pore types for He, Ne, Ar, Kr, H2, N2, CO, and CO2 gases, and use the data to assess their capability for selective gas separation. Our calculations indicate that crystalline bilayer silica, which is less than a nanometer thick, can be a high-selectivity and high-permeance membrane material for 3He/4He, He/natural gas, and H2/CO separations.