Phase transition systematics in BiVO4 by means of high-pressure-high-temperature Raman experiments

"We report here high-pressure-high-temperature Raman experiments performed on BiVO4. We characterized the fergusonite and scheelite phases (powder and single crystal samples) and the zircon polymorph (nanopowder). The experimental results are supported by ab initio calculations, which, in addition, provide the vibrational patterns. The temperature and pressure behavior of the fergusonite lattice modes reflects the distortions associated with the ferroelastic instability. The linear coefficients of the zircon phase are in sharp contrast to the behavior observed in the fergusonite phase. The boundary of the fergusonite-to-scheelite second-order phase transition is given by TF-Sch (K) = -166(8)P(GPa) + 528(5). The zircon-to-scheelite, irreversible, first-order phase transition takes place at T-Z-(Sch )(K) = -107(8)P(GPa) + 690(10). We found evidence of additional structural changes around 15.7 GPa, which in the downstroke were found to be not reversible. We analyzed the anharmonic contribution to the wave-number shift in fergusonite using an order parameter. The introduction of a critical temperature depending both on temperature and pressure allows for a description of the results of all the experiments in a unified way.

Barriers of mental health treatment utilization among first-year college students: First cross-national results from the WHO World Mental Health International College Student Initiative.

BACKGROUND: Although mental disorders and suicidal thoughts-behaviors (suicidal thoughts and behaviors) are common among university students, the majority of students with these problems remain untreated. It is unclear what the barriers are to these students seeking treatment. AIMS: The aim of this study is to examine the barriers to future help-seeking and the associations of clinical characteristics with these barriers in a cross-national sample of first-year college students. METHOD: As part of the World Mental Health International College Student (WMH-ICS) initiative, web-based self-report surveys were obtained from 13,984 first-year students in eight countries across the world. Clinical characteristics examined included screens for common mental disorders and reports about suicidal thoughts and behaviors. Multivariate regression models adjusted for socio-demographic, college-, and treatment-related variables were used to examine correlates of help-seeking intention and barriers to seeking treatment. RESULTS: Only 24.6% of students reported that they would definitely seek treatment if they had a future emotional problem. The most commonly reported reasons not to seek treatment among students who failed to report that they would definitely seek help were the preference to handle the problem alone (56.4%) and wanting to talk with friends or relatives instead (48.0%). Preference to handle the problem alone and feeling too embarrassed were also associated with significantly reduced odds of having at least some intention to seek help among students who failed to report that they would definitely seek help. Having 12-month major depression, alcohol use disorder, and suicidal thoughts and behaviors were also associated with significantly reduced reported odds of the latter outcome. CONCLUSIONS: The majority of first-year college students in the WMH-ICS surveys report that they would be hesitant to seek help in case of future emotional problems. Attitudinal barriers and not structural barriers were found to be the most important reported reasons for this hesitation. Experimental research is needed to determine whether intention to seek help and, more importantly, actual help-seeking behavior could be increased with the extent to which intervention strategies need to be tailored to particular student characteristics. Given that the preference to handle problems alone and stigma and appear to be critical, there could be value in determining if internet-based psychological treatments, which can be accessed privately and are often build as self-help approaches, would be more acceptable than other types of treatments to student who report hesitation about seeking treatment.status: publishe

WHO World Mental Health Surveys International College Student Project: Prevalence and Distribution of Mental Disorders

Increasingly, colleges across the world are contending with rising rates of mental disorders, and in many cases, the demand for services on campus far exceeds the available resources. The present study reports initial results from the first stage of the WHO World Mental Health International College Student project, in which a series of surveys in 19 colleges across 8 countries (Australia, Belgium, Germany, Mexico, Northern Ireland, South Africa, Spain, United States) were carried out with the aim of estimating prevalence and basic sociodemographic correlates of common mental disorders among first-year college students. Web-based self-report questionnaires administered to incoming first-year students (45.5% pooled response rate) screened for six common lifetime and 12-month DSM-IV mental disorders: major depression, mania/hypomania, generalized anxiety disorder, panic disorder, alcohol use disorder, and substance use disorder. We focus on the 13,984 respondents who were full-time students: 35% of whom screened positive for at least one of the common lifetime disorders assessed and 31% screened positive for at least one 12-month disorder. Syndromes typically had onsets in early to middle adolescence and persisted into the year of the survey. Although relatively modest, the strongest correlates of screening positive were older age, female sex, unmarried-deceased parents, no religious affiliation, nonheterosexual identification and behavior, low secondary school ranking, and extrinsic motivation for college enrollment. The weakness of these associations means that the syndromes considered are widely distributed with respect to these variables in the student population. Although the extent to which cost-effective treatment would reduce these risks is unclear, the high level of need for mental health services implied by these results represents a major challenge to institutions of higher education and governments. (PsycINFO Database Record (c) 2018 APA, all rights reserved).status: publishe

Supramolecular Chirality of Hydrogen-Bonded Rosette Assemblies \ud

The control of chirality in synthetic self-assembled systems remains challenging because of their lower stability and their higher susceptibility to racemization when compared to covalent systems. In this review the supramolecular chirality of noncovalent hydrogen-bonded assemblies formed by multiple cooperative hydrogenbonds between calix[4]arene dimelamines and cyanurates or barbiturates derivatives (rosette assemblies) are described. It is shown that the amplification of chirality (a high enantiomeric or diastereomeric excess induced by a small initial amount of chiral bias) of double and tetrarosette assemblies is influenced by bulky substitution on their components and electronic properties of the substituents as well as their proximity to the rosette core. In the absence of chiral centers in their components, the assemblies form as a racemic mixture of both enantiomers (P and M). The synthesis of enantiomerically pure rosette assemblies is conducted via induction of chirality using chiral barbiturates, followed by substitution of the chiral components for achiral cyanurates (chiral memory concept). The addition of an external auxiliary to a racemic mixture of P and M assemblies leading to the formation of one of the two possible diastereomeric assemblies is also described. Moreover, chiral resolution of self-assembled nanostructures on highly oriented pyrolytic graphite (HOPG) surfaces is also discussed. \ud \u

Enhanced stability of large molecules vacuumsublimated onto AU(111) achieved by incorporation of coordinated AU-atoms

The stability against fragmentation of a large organic compound (calix[4]arene dimelamine derivative) sublimated onto a Au(111) surface under ultrahigh vacuum conditions has been investigated by scanning tunneling microscopy. By coordinating the compound to gold atoms prior to deposition its stability can be significantly enhanced, which suggests a new route toward improved processability of large organic building blocks for on-surface self-assembly of functional nanostructure

Self-Organization of Gold-Containing Hydrogen-Bonded Rosette Assemblies on Graphite Surface\ud

The self-organization of supramolecular structures, in particular gold-containing hydrogen-bonded rosettes, on highly oriented pyrolytic graphite (HOPG) surfaces was investigated by tapping-mode atomic force microscopy (TM-AFM) and scanning tunneling microscopy (STM). TM-AFM and high-resolution STM results show that these hydrogen-bonded assemblies self-organize to form highly ordered domains on HOPG surfaces. We find that a subtle change in one of the building blocks induces two different orientations of the assembly with respect to the surface. These results provide information on the control over the construction of supramolecular nanoarchitectures in 2D with the potential for the manufacturing of functional materials based on structural manipulation of molecular components. \u

Severe role impairment associated with mental disorders: results of the WHO World Mental Health Surveys International College Student Project

BACKGROUND: College entrance is a stressful period with a high prevalence of mental disorders. AIMS: To assess the role impairment associated with 12-month mental disorders among incoming first-year college students within a large cross-national sample. METHODS: Web-based self-report surveys assessing the prevalence of DSM-IV mental disorders and health-related role impairment (Sheehan Disability Scale) were obtained and analyzed from 13,984 incoming first-year college students (Response = 45.5%), across 19 universities in eight countries. Impairment was assessed in the following domains: home management, work (e.g., college-related problems), close personal relationships, and social life. ESULTS: Mean age of the sample was 19.3 (SD = 0.59) and 54.4% were female. Findings showed that 20.4% of students reported any severe role impairment (10% of those without a mental disorder vs. 42.9% of those with at least one disorder, P < 0.01). In bivariate analyses, panic disorder, and mania were associated most frequently with severe impairment (60.6% and 57.5%, respectively). Students reporting three or more mental disorders had almost fivefold more frequently severe impairment relative to those without mental disorders. Multiple logistic regression showed that major depression (OR = 4.0; 95%CI = 3.3, 4.8), generalized anxiety (OR = 3.9; 95%CI = 3.1, 4.8), and panic disorder (OR = 2.9; 95%CI 2.4, 4.2) were associated with the highest odds of severe impairment. Only minimal deviations from these overall associations were found across countries. CONCLUSION: Mental disorders among first-year college students are associated with substantial role impairment. Providing preventative interventions targeting mental disorders and associated impairments is a critical need for institutions to address