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Background: Widely used psychotropic medications for obsessive-compulsive disorder (OCD) may change the volumes of subcortical brain structures, and differently in children vs. adults. We measured subcortical volumes cross-sectionally in patients finely stratified for age taking various common classes of OCD drugs. Methods: The ENIGMA-OCD consortium sample (1081 medicated/1159 unmedicated OCD patients and 2057 healthy controls aged 6–65) was divided into six successive 6–10-year age-groups. Individual structural MRIs were parcellated automatically using FreeSurfer into 8 regions-of-interest (ROIs). ROI volumes were compared between unmedicated and medicated patients and controls, and between patients taking serotonin reuptake inhibitors (SRIs), tricyclics (TCs), antipsychotics (APs), or benzodiazepines (BZs) and unmedicated patients. Results: Compared to unmedicated patients, volumes of accumbens, caudate, and/or putamen were lower in children aged 6–13 and adults aged 50–65 with OCD taking SRIs (Cohen's d = −0.24 to −0.74). Volumes of putamen, pallidum (d = 0.18–0.40), and ventricles (d = 0.31–0.66) were greater in patients aged 20–29 receiving APs. Hippocampal volumes were smaller in patients aged 20 and older taking TCs and/or BZs (d = −0.27 to −1.31). Conclusions: Results suggest that TCs and BZs could potentially aggravate hippocampal atrophy of normal aging in older adults with OCD, whereas SRIs may reduce striatal volumes in young children and older adults. Similar to patients with psychotic disorders, OCD patients aged 20–29 may experience subcortical nuclear and ventricular hypertrophy in relation to APs. Although cross-sectional, present results suggest that commonly prescribed agents exert macroscopic effects on subcortical nuclei of unknown relation to therapeutic response.

Objective: Cognitive-behavioral therapy (CBT) is considered a first-line treatment for obsessive-compulsive disorder (OCD) in pediatric and adult populations. Nevertheless, some patients show partial or null response. The identification of predictors of CBT response may improve clinical management of patients with OCD. Here, we aimed to identify structural magnetic resonance imaging (MRI) predictors of CBT response in 2 large series of children and adults with OCD from the worldwide ENIGMA-OCD consortium. Method: Data from 16 datasets from 13 international sites were included in the study. We assessed which variations in baseline cortical thickness, cortical surface area, and subcortical volume predicted response to CBT (percentage of baseline to post-treatment symptom reduction) in 2 samples totaling 168 children and adolescents (age range 5-17.5 years) and 318 adult patients (age range 18-63 years) with OCD. Mixed linear models with random intercept were used to account for potential cross-site differences in imaging values. Results: Significant results were observed exclusively in the pediatric sample. Right prefrontal cortex thickness was positively associated with the percentage of CBT response. In a post hoc analysis, we observed that the specific changes accounting for this relationship were a higher thickness of the frontal pole and the rostral middle frontal gyrus. We observed no significant effects of age, sex, or medication on our findings. Conclusion: Higher cortical thickness in specific right prefrontal cortex regions may be important for CBT response in children with OCD. Our findings suggest that the right prefrontal cortex plays a relevant role in the mechanisms of action of CBT in children.

A key challenge for addressing micro- and nanoplastics (MNPs) in the environment is being able to characterize their chemical properties, morphologies, and quantities in complex matrices. Current techniques, such as Fourier transform infrared spectroscopy, provide these broad characterizations but are unsuitable for studying MNPs in spectrally congested or complex chemical environments. Here, we introduce a new, super-resolution infrared absorption technique to characterize MNPs, called infrared photothermal heterodyne imaging (IR-PHI). IR-PHI has a spatial resolution of ∼300 nm and can determine the chemical identity, morphology, and quantity of MNPs in a single analysis with high sensitivity. Specimens are supported on CaF2 coverslips under ambient conditions from where we (1) quantify MNPs from nylon tea bags after steeping in ultrapure water at 25 and 95 °C, (2) identify MNP chemical or morphological changes after steeping at 95 °C, and (3) chemically identify MNPs in sieved road dust. In all cases, no special sample preparation was required. MNPs released from nylon tea bags at 25 °C were fiber-like and had characteristic IR frequencies corresponding to thermally extruded nylon. At 95 °C, degradation of the nylon chemical structure was observed via the disappearance of amide group IR frequencies, indicating chain scission of the nylon backbone. This degradation was also observed through morphological changes, where MNPs altered shape from fiber-like to quasi-spherical. In road dust, IR-PHI analysis reveals the presence of numerous aggregate and single-particle (

Mixing bromine and iodine within lead halide perovskites is a common strategy to tune their optical properties. This comes at the cost of instability, as illumination induces halide segregation and degrades device performances. Hence, understanding the behavior of mixed-halide perovskites is crucial for applications. In 3D perovskites such as MAPb(Br

Photoinduced halide segregation in mixed halide hybrid perovskites [i.e., APb(I1–xBrx)3] represents an intrinsic instability that impedes their commercialization. Resolving this issue requires deve...

Accurate measurements of semiconductor nanocrystal (NC) emission quantum yields (QYs) are critical to condensed phase optical refrigeration. Of particular relevance to measuring NC QYs is a longstanding debate as to whether an excitation energy-dependent (EED) QY exists. Various reports indicate existence of NC EED QYs, suggesting that the phenomenon is linked to specific ensemble properties. We therefore investigate here the existence of EED QYs in two NC systems (CsPbBr3 and CdSe) that are possible candidates for use in optical refrigeration. The influence of NC size, size-distribution, surface ligand, and as-made emission QYs are investigated. Existence of EED QYs is assessed using two approaches (an absolute approach using an integrating sphere and a relative approach involving excitation spectroscopy). Altogether, our results show no evidence of EED QYs across samples. This suggests that parameters beyond those mentioned above are responsible for observations of NC EED QYs.

ConspectusThe optical and electronic properties of metal halide perovskites provide insight into the operation of solar cells as well as their long-term operational stability. Halide mobility in perovskite films is an important factor influencing solar cell performance. One can visualize halide ion migration through halide exchange between two nanocrystal suspensions or between physically paired films of two different metal halide perovskites. The ability to tune band gap by varying halide ratios (Cl:Br or Br:I) allows the synthesis of mixed halide perovskites with tailored absorption and emission across the entire visible spectrum. Interestingly, mixed halide (e.g., MAPb(Br0.5I0.5)3) films undergo phase segregation to form Br-rich and I-rich sites under steady state illumination. Upon halting illumination, segregated phases mix to restore original mixed halide compositions. Introducing multiple cations (Cs, formamidinium) at the A site or alloying with Cl greatly suppresses halide mobilities. Long-term irradiation of MAPb(Br0.5I0.5)3 films also cause expulsion of iodide leaving behind Br-rich phases. Hole trapping at I-rich sites in MAPb(Br0.5I0.5)3 is considered to be an important step in inducing halide mobility in photoirradiated films. This Account focuses on halide ion migration in nanocrystals and nanostructured films driven by entropy of mixing in dark and phase segregation under light irradiation.

Ion migration represents an intrinsic instability of metal halide perovskite solar cells. Here we show that triple-cation FAxMAyCs1–x–yPbI3 [FA+ = (NH2)2CH+, MA+ = CH3NH3+] active layers with mixed...

Infrared photothermal heterodyne imaging (IR-PHI) is an all-optical table top approach that enables super-resolution mid-infrared microscopy and spectroscopy. The underlying principle behind IR-PHI is the detection of photothermal changes to specimens induced by their absorption of infrared radiation. Because detection of resulting refractive index and scattering cross section changes is done using a visible (probe) laser, IR-PHI exhibits a spatial resolution of ∼300 nm. This is significantly below the mid-infrared diffraction limit and is unlike conventional infrared absorption microscopy where spatial resolution is of order ∼5μm. Despite having achieved mid-infrared super-resolution, IR-PHI’s spatial resolution is ultimately limited by the visible probe laser’s diffraction limit. This hinders immediate application to studying samples residing in spatially congested environments. To circumvent this, we demonstrate further enhancements to IR-PHI’s spatial resolution using a deep learning network that addresses the Abbe diffraction limit as well as background artifacts, introduced by experimental raster scanning. What results is a twofold improvement in feature resolution from 300 to ∼150 nm.

This perspective highlights recent advances in super-resolution, mid-infrared imaging and spectroscopy. It provides an overview of the different near field microscopy techniques developed to address the problem of chemically imaging specimens in the mid-infrared "fingerprint" region of the spectrum with high spatial resolution. We focus on a recently developed far-field optical technique, called infrared photothermal heterodyne imaging (IR-PHI), and discusses the technique in detail. Its practical implementation in terms of equipment used, optical geometries employed, and underlying contrast mechanism are described. Milestones where IR-PHI has led to notable advances in bioscience and materials science are summarized. The perspective concludes with a future outlook for robust and readily accessible high spatial resolution, mid-infrared imaging and spectroscopy techniques.

The rising demand for clean energy requires efficient as well as simple and cost-effective systems to be found to convert solar energy into electricity or chemical fuels. Colloidal nanomaterials, especially metal chalcogenides, are among the most promising candidates for energy applications. This is because of their well-developed surface chemistries, ease of heterostructure creation, superior light-harvesting abilities, and tunable optical and electronic properties, which stem from quantum confinement effects. The photocatalytic efficiencies of metal chalcogenides, however, are limited by slow redox processes that occur on their surfaces. These redox processes occur on timescales much slower than native charge carrier recombination processes. Consequently, to increase photocatalytic efficiencies, photogenerated charge carrier lifetimes must be increased. This entails enhancing the spatial separation of electrons and holes in order to prevent their recombination. This review outlines the most popular strategies employed today to improve the photocatalytic performance of II–VI nanostructures.

Hole trapping at iodine (I) sites in MAPbBr1.5I1.5 mixed halide perovskites (MHP) is responsible for iodine migration and its eventual expulsion into solution. We have now modulated the photoinduce...

Infrared photothermal heterodyne imaging (IR-PHI) is an established all-optical, table-top approach for conducting super-resolution mid-infrared microscopy and spectroscopy on submicrometer-sized particles. The instrument’s capabilities are highlighted by its ability to operate in spectroscopically-crowded environments. This includes specimens obtained from environmental matrices where particulates with different morphologies, chemical compositions, and abundances exist. Here, proof-of-concept IR-PHI measurements have been conducted on anthropogenic micro- and nanoplastics (MNPs) derived from the breakdown of consumer products. In particular, IR-PHI is used to characterize MNPs extracted from steeped plastic teabags and floor dust from a household vacuum. IR-PHI results reveal the presence of complex MNP structures made of polyamide fibers and acrylonitrile butadiene styrene MNPs.

Semiconductor nanocrystals (NCs) are potential materials for verifiable demonstrations of semiconductor-based laser cooling. The key feature that makes NCs appealing for laser cooling is their near unity emission quantum yields (QYs). An unresolved issue regarding NC QYs, however, centers on the existence of an excitation energy dependent (EED) QY. Here, we study EED QYs on three NC systems, aimed at demonstrating NC-based laser cooling (CsPbBr3, CsPbI3, and CdSe/CdS core/shell NCs). We evaluate the impact of EED QYs using two approaches. The first involves direct QY measurements using an integrating sphere. The second entails photoluminescence excitation spectroscopy where changes to NC QYs with excitation energy can be assessed qualitatively.

ObjectiveNo diagnostic biomarkers are available for obsessive-compulsive disorder (OCD). Magnetic resonance imaging (MRI) studies have provided evidence for structural abnormalities in distinct brain regions, but effect sizes are small and have limited clinical relevance. To investigate whether individual patients can be distinguished from healthy controls, we performed multivariate analysis of structural neuroimaging data from the ENIGMA-OCD consortium.MethodWe included 46 data sets with neuroimaging and clinical data from adult (≥18 years) and pediatric (1images from 2,304 OCD patients and 2,068 healthy controls were analyzed using standardized processing to extract regional measures of cortical thickness, surface area and subcortical volume. Machine learning classification performance was tested using cross-validation, and possible effects of clinical variables were investigated by stratification.ResultsClassification performance for OCD versus controls using the complete sample with different classifiers and cross-validation strategies was poor (AUC—0.57 (standard deviation (SD)=0.02;Pcorr=0.19) to 0.62 (SD=0.03;Pcorrcorr>.99) to 0.54 (SD=0.08;Pcorr>.99)). In contrast, good classification performance (>0.8 AUC) was achieved within subgroups of patients split according to their medication status.ConclusionsParcellated structural MRI data do not enable good distinction between patients with OCD and controls. However, classifying subgroups of patients based on medication status enables good identification at the individual subject level. This underlines the need for longitudinal studies on the short- and long-term effects of medication on brain structure.

ObjectiveAttention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and obsessive-compulsive disorder (OCD) are common neurodevelopmental disorders that frequently co-occur. We aimed to directly compare all three disorders. The ENIGMA consortium is ideally positioned to investigate structural brain alterations across these disorders.MethodsStructural T1-weighted whole-brain MRI of controls (n=5,827) and patients with ADHD (n=2,271), ASD (n=1,777), and OCD (n=2,323) from 151 cohorts worldwide were analyzed using standardized processing protocols. We examined subcortical volume, cortical thickness and surface area differences within a mega-analytical framework, pooling measures extracted from each cohort. Analyses were performed separately for children, adolescents, and adults using linear mixed-effects models adjusting for age, sex and site (and ICV for subcortical and surface area measures).ResultsWe found no shared alterations among all three disorders, while shared alterations between any two disorders did not survive multiple comparisons correction. Children with ADHD compared to those with OCD had smaller hippocampal volumes, possibly influenced by IQ. Children and adolescents with ADHD also had smaller ICV than controls and those with OCD or ASD. Adults with ASD showed thicker frontal cortices compared to adult controls and other clinical groups. No OCD-specific alterations across different age-groups and surface area alterations among all disorders in childhood and adulthood were observed.ConclusionOur findings suggest robust but subtle alterations across different age-groups among ADHD, ASD, and OCD. ADHD-specific ICV and hippocampal alterations in children and adolescents, and ASD-specific cortical thickness alterations in the frontal cortex in adults support previous work emphasizing neurodevelopmental alterations in these disorders.

Accepted Manuscript, BACKGROUND: Lateralized dysfunction has been suggested in obsessive-compulsive disorder (OCD). However, it is currently unclear whether OCD is characterized by abnormal patterns of brain structural asymmetry. Here we carried out what is by far the largest study of brain structural asymmetry in OCD.METHODS: We studied a collection of 16 pediatric datasets (501 patients with OCD and 439 healthy control subjects), as well as 30 adult datasets (1777 patients and 1654 control subjects) from the OCD Working Group within the ENIGMA (Enhancing Neuro Imaging Genetics through Meta Analysis) Consortium. Asymmetries of the volumes of subcortical structures, and of measures of regional cortical thickness and surface areas, were assessed based on T1-weighted magnetic resonance imaging scans, using harmonized image analysis and quality control protocols. We investigated possible alterations of brain asymmetry in patients with OCD. We also explored potential associations of asymmetry with specific aspects of the disorder and medication status.RESULTS: In the pediatric datasets, the largest case-control differences were observed for volume asymmetry of the thalamus (more leftward; Cohen's d = 0.19) and the pallidum (less leftward; d = -20.21). Additional analyses suggested putative links between these asymmetry patterns and medication status, OCD severity, or anxiety and depression comorbidities. No significant case-control differences were found in the adult datasets.CONCLUSIONS: The results suggest subtle changes of the average asymmetry of subcortical structures in pediatric OCD, which are not detectable in adults with the disorder. These findings may reflect altered neurodevelopmental processes in OCD., This research was funded by the Max Planck Society (Germany). Additional funding was from the Japan Society for the Promotion of Science (KAKENHI Grant No. 18K15523 [to YA], KAKENHI Grant No. 16K04344 [to YH], KAKENHI Grant Nos. 16K19778 and 18K07608 [to TNakam], and KAKENHI Grant No. 26461762 [to AN]); the Carlos III Health Institute (Grant No. PI14/00419 [to PA], Grant No. PI040829 cofunded by European Regional Development Fund [to LL], Grant No. FI17/00294 [to IM-Z], Grant No. PI16/00950 [to JMM], and Grant Nos. CPII16/00048, PI13/01958, and PI16/00889 cofunded by European Regional Development Funds [to CS-M]); the Ontario Mental Health Foundation (Research Training Fellowship [to SHA]); Alberta Innovates Translational Health Chair in Child and Youth Mental Health (to PDA), the Ontario Brain Institute (to PDA); the National Institute of Mental Health (Grant No. K23MH104515 [to JTB], Grant No. K23-MH092397 [to BPB], Grant No. K23MH082176 [to KDF), Grant No. R21MH101441 [to RM], Grant No. R01MH081864 [to JO and JP], and Grant No. R01MH085900 [to JO and JF], Grant No. R21MH093889 [to HBS]); Fundação de Amparo à Pesquisa do Estado de São Paulo (Grant No. 2011/21357–9 [to MCB], Grant No. 2011/21357–9 [to GFB], Grant No. 2011/21357–9 [to MQH], and Grant No. 2011/21357–9 [to ECM]); the Swiss National Science Foundation (Grant No. 320030_130237 [to SB; principal investigator, Susanne Walitza]); the Hartmann Müller Foundation (Grant No. 1460 [to SB]); the David Judah Fund at the Massachusetts General Hospital (to BPB); EU FP7 Project TACTICS (Grant No. 278948 [to JB]); the National Natural Science Foundation of China (Grant No. 81560233 [to YC] and Grant No. 81371340 [to ZW]); the International OCD Foundation (Grant No. K23 MH115206 [to PG]); the Wellcome Sir Henry Dale Fellowship (Grant No. 211155/Z/18/Z [to TUH]); the Jacobs Foundation (to TUH); the Brain and Behavior Research Foundation (2018 NARSAD Young Investigator Grant No. 27023 [to TUH]); the Agency for Medical Research and Development (Grant No. JP18dm0307002 [to YH]); the Michael Smith Foundation for Health Research (to FJ-F); the Federal Ministry of Education and Research of Germany (Grant No. BMBF-01GW0724 [to NK]); the Deutsche Forschungsgemeinschaft (Grant No. KO 3744/7–1 [to KK]); the Helse Vest Health Authority (Grant Nos. 911754 and 911880 [to GK]); the Norwegian Research Council (Grant No. HELSEFORSK 243675 [to GK]); the Marató TV3 Foundation (Grant Nos. 01/2010 and 091710 [to LL]); the Agency for Management of University and Research Grants (Grant No. 2017 SGR 881 [to LL] and 2017 SGR 1247 from the Generalitat de Catalunya [to JMM]); Fundação para a Ciência e a Tecnologia (Grant No. PDE/BDE/113604/2015 from the PhD-iHES Program [to RM], Grant No. PDE/BDE/113601/2015 from the PhD-iHES Program [to PSM]); the Japanese Ministry of Education, Culture, Sports, Science and Technology (Grant-in-Aid for Scientific Research (Grant Nos. 22591262, 25461732, and 16K10253 [to TNakao]); the Government of India Department of Science and Technology (DST INSPIRE Faculty Grant No. -IFA12-LSBM-26 [to JCN] and Grant No. SR/S0/HS/0016/2011 [to YCJR]); the Government of India Department of Biotechnology (Grant No. BT/06/IYBA/2012 [to JCN] and Grant No. BT/PR13334/Med/30/259/2009 [to YCJR]); the New York State Office of Mental Health (to HBS); the Italian Ministry of Health (Grant No. RC13-14-15-16A [to GS]); the National Center for Advancing Translational Sciences (Grant No. UL1TR000067/KL2TR00069 [to ERS]); the Canadian Institutes of Health Research (to SES); the Michael Smith Foundation for Health Research (to SES); the British Columbia Provincial Health Services Authority (to SES); the Netherlands Organization for Scientific Research (Grant No. NWO/ZonMW Vidi 917.15.318 [to GAvW]); the Wellcome-DBT India Alliance (Grant No. 500236/Z/11/Z [to GV]); the Shanghai Key Laboratory of Psychotic Disorders (Grant No. 13dz2260500 [to ZW]).

Size-dependent photoluminescence Stokes shifts (ΔEs) universally exist in CsPbX3 (X = Cl-, Br-, or I-) perovskite nanocrystals (NCs). ΔEs values, which range from ∼15 to 100 meV for NCs with average edge lengths (l) from approximately 13 to 3 nm, are halide-dependent such that ΔEs(CsPbI3) > ΔEs(CsPbBr3) ≳ ΔEs(CsPbCl3). Observed size-dependent Stokes shifts are not artifacts of ensemble size distributions as demonstrated through measurements of single CsPbBr3 NC Stokes shifts (⟨ΔEs⟩ = 42 ± 5 meV), which are in near quantitative agreement with associated ensemble (l = 6.8 ± 0.8 nm) ΔEs values (ΔEs ≈ 50 meV). Transient differential absorption measurements additionally illustrate no significant spectral dynamics on the picosecond time scale that would contribute to ΔEs. This excludes polaron formation as being responsible for ΔEs. Altogether, the results point to an origin for ΔEs, intrinsic to the size-dependent electronic properties of individual perovskite NCs.

Establishing the optical refrigeration of semiconductors remains a longstanding goal due to potential applications in optoelectronics. Apart from stringent materials requirements, required to realize condensed phase laser cooling, namely the need to have near unity emission quantum yields, a practical challenge involves accurately measuring specimen temperatures in a non-contact fashion. Common all-optical approaches developed in response to this need include: pump– probe luminescence thermometry (PPLT) and differential luminescence thermometry (DLT). In this study, we compare and contrast PPLT and DLT to a newly developed up-conversion emission thermometry to establish the most robust approach for measuring semiconductor nanocrystal (NC) temperatures. Using high external quantum efficiency CdSe/CdS core/shell NCs, we reveal that up-conversion emission thermometry possesses higher accuracy than either PPLT or DLT. Up-conversion emission thermometry can also be used on specimens such as CsPbBr3 NCs with temperature-insensitive band gaps.

Light-induced halide segregation is an intrinsic instability of mixed-halide perovskites, which complicates their successful use in tandem solar cells. Methods to suppress this phenomenon remain elusive because of its ambiguous origin. Beal et al. demonstrate that photostability is not an exclusive property of perovskite crystal structure and instead highlight the need for a microscopic understanding of the phenomenon.

The atomic structure of CsPbBr3 nanocubes (NCs) was studied at the single-particle level via a high-resolution transmission electron microscopy (HRTEM) defocus-series analysis. The technique entails acquiring lattice-resolved HRTEM images of individual NCs over progressive defocus values. CsPbBr3 NC atomic structure was evaluated by comparing acquired experimental data to simulated lattice-resolved images and corresponding Fourier transform patterns of both orthorhombic (Pnma) and cubic (Pm3m) CsPbBr3 polymorphs. Herein, CsPbBr3 NCs with average edge lengths (l) of l ∼ 10 and 5 nm are analyzed using the aforementioned technique. In the former, we find evidence for the coexistence of both cubic and orthorhombic lattices. In the latter, solely cubic character is observed, illustrating a potential size dependency to the crystal symmetry of CsPbBr3 NCs. Such structural measurements provide critical insight into elucidating the structure/(optical and electrical) function relationship of CsPbBr3 NCs.

Solution-processed mixed halide perovskites are excellent materials for multijunction solar cells. Unfortunately, light-induced halide phase segregation has prevented their effective integration into working devices. In this study, we rationalize and quantify anion photosegregation in stoichiometric and halide-deficient MAPb(I1–xBrx)3 thin films through kinetic Monte Carlo simulations and complementary optical measurements. Our study reveals that segregation rates are dictated by halide vacancy hopping barriers and are modulated by vacancy concentrations. The simulations further suggest that near-ubiquitous emission energies, which converge on that for MAPb(I0.8Br0.2)3 (i.e., x ≈ 0.2) following photosegregation, arise from the existence of kinetically trapped Br– within nucleated I-rich domains. An established photosegregation excitation intensity threshold is independent of the number of vacancies and instead depends critically on parameters such as carrier diffusion length, lifetime, and bandgap tunabil...

The ease of halide ion exchange in metal halide nanocrystals offers an opportunity to utilize them in a layered or tandem fashion to achieve graded bandgap films. We have now successfully suppressed the halide ion exchange by capping CsPbBr3 and CsPbI3 nanocrystals with PbSO4–oleate to create a nanostructure assembly that inhibits the exchange of anions. Absorption measurements show that the nanocrystal assemblies maintain their identity as either CsPbBr3 or CsPbI3 for several days. Furthermore, the effect of PbSO4–oleate capping on the excited state dynamics has also been elucidated. The effectiveness of PbSO4–oleate capping of lead halide perovskite nanocrystals offers new opportunities to overcome the challenges of halide ion exchange and aid toward the tandem design of perovskite light-harvesting assemblies.