A pocket-factor-triggered conformational switch in the hepatitis B virus capsid.

Viral hepatitis is growing into an epidemic illness, and it is urgent to neutralize the main culprit, hepatitis B virus (HBV), a small-enveloped retrotranscribing DNA virus. An intriguing observation in HB virion morphogenesis is that capsids with immature genomes are rarely enveloped and secreted. This prompted, in 1982, the postulate that a regulated conformation switch in the capsid triggers envelopment. Using solid-state NMR, we identified a stable alternative conformation of the capsid. The structural variations focus on the hydrophobic pocket of the core protein, a hot spot in capsid-envelope interactions. This structural switch is triggered by specific, high-affinity binding of a pocket factor. The conformational change induced by the binding is reminiscent of a maturation signal. This leads us to formulate the "synergistic double interaction" hypothesis, which explains the regulation of capsid envelopment and indicates a concept for therapeutic interference with HBV envelopment.

Pectus excavatum in motion: dynamic evaluation using real-time MRI.

OBJECTIVES: The breathing phase for the determination of thoracic indices in patients with pectus excavatum is not standardized. The aim of this study was to identify the best period for reliable assessments of morphologic indices by dynamic observations of the chest wall using real-time MRI. METHODS: In this prospective study, patients with pectus excavatum underwent morphologic evaluation by real-time MRI at 3 T between January 2020 and June 2021. The Haller index (HI), correction index (CI), modified asymmetry index (AI), and modified eccentricity index (EI) were determined during free, quiet, and forced breathing respectively. Breathing-related differences in the thoracic indices were analyzed with the Wilcoxon signed-rank test. Motion of the anterior chest wall was analyzed as well. RESULTS: A total of 56 patients (11 females and 45 males, median age 15.4 years, interquartile range 14.3-16.9) were included. In quiet expiration, the median HI in the cohort equaled 5.7 (4.5-7.2). The median absolute differences (Δ) in the thoracic indices between peak inspiration and peak expiration were ΔHI = 1.1 (0.7-1.6, p < .001), ΔCI = 4.8% (1.3-7.5%, p < .001), ΔAI = 3.0% (1.0-5.0%, p < .001), and ΔEI = 8.0% (3.0-14.0%, p < .05). The indices varied significantly during different inspiratory phases, but not during expiration (p > .05 each). Furthermore, the dynamic evaluation revealed three distinctive movement patterns of the funnel chest. CONCLUSIONS: Real-time MRI reveals patterns of chest wall motion and indicate that thoracic indices of pectus excavatum should be assessed in the end-expiratory phase of quiet expiration. KEY POINTS: • The thoracic indices in patients with pectus excavatum depend on the breathing phase. • Quiet expiration represents the best breathing phase for determining thoracic indices. • Real-time MRI can identify different chest wall motion patterns in pectus excavatum.

Family risk and early attachment development: The differential role of parental sensitivity.

Family risks are known to be detrimental to children's attachment development. This study investigated whether parental sensitivity plays different roles in early attachment development in the context of risk: Sensitivity was hypothesized to mediate risk effects on attachment, as well as a moderator that shapes the relation between risk and attachment. Multiple family risks, parental sensitivity (defined as responsivity and supportive presence), and children's attachment security of 197 infants and toddlers (Mage  = 15.25 months) and their caregivers were assessed in a prospective study with a cohort-sequential-design in Germany. Caregivers' sensitivity served as a mediator of risk effects on attachment as well as a moderator that buffers adverse consequences of risk. Early sensitivity might be relevant in setting the stage for attachment development supporting resilience.

A los riesgos familiares se les conoce como perjudiciales para el desarrollo de la afectividad en los niños. Este estudio investigó si la sensibilidad del progenitor juega diferentes papeles en el temprano desarrollo de la afectividad en el contexto de riesgo: La hipótesis es que la sensibilidad sirve de intermediaria de los efectos del riesgo sobre la afectividad, y también como una moderadora que moldea la relación entre el riesgo y la afectividad. Los riesgos familiares múltiples, la sensibilidad del progenitor (definida como la presencia de receptividad y apoyo) y la seguridad de la afectividad del niño en 197 infantes y niños pequeñitos (M = 15.25 meses) y de quienes les cuidaban fueron evaluadas en un estudio de probabilidad con un diseño secuencial de grupo en Alemania. La sensibilidad de quien presta el cuidado sirvió como mediadora de los efectos del riesgo sobre la afectividad, así como también de moderadora que amortigua las consecuencias adversas del riesgo. La temprana sensibilidad pudiera ser relevante para sentar las bases de la fortaleza de resistencia de apoyo al desarrollo de la afectividad.

Les risques de la famille sont connus comme étant préjudiciables au développement de l'attachement des enfants. Cette étude s'est attachée à étudier si la sensibilité parentale joue des rôles différents dans le développement précoce de l'attachement dans le contexte de risque: on a pris comme hypothèse que la sensibilité a servi de médiatrice aux effets de risque sur l'attachement, et a également servi de modératrice qui forme la relation entre le risqué et l'attachement. Les risques familiaux multiples, la sensibilité parentale (définie comme réceptivité et présence de soutien), et la sécurité de l'attachement de 197 nourrissons et jeunes enfants (M = 15,25 mois) et des personnes prenant soin d'eux ont été évalués dans une étude prospective avec un plan séquentiel-cohorte, en Allemagne. La sensibilité de la personne prenant soin de l'enfant a servi de médiateur pour les effets de risque sur l'attachement ainsi que de modérateur qui amorti les conséquences adverses de risque. La sensibilité précoce peut s'avérer pertinente dans la préparation du terrain pour le développement de l'attachement qui souvient la résilience.

Bunk-Bed-Related Fractures in Children: Are We Aware of the Risks?

Background and Objectives: Falls from heights are a common mechanism of trauma in children. However, data on bunk-bed-related (BBR) fractures are scarce. We aimed to assess types of fractures and age groups most at risk for BBR fractures. Material and Methods: We analyzed medical records and imaging procedures of patients aged <18 years who sustained a bunk bed injury and were treated at our department between January 2014 and December 2021. Demographic data, including age groups, mechanisms, types and anatomical regions of fractures, were assessed. Results: A total of 162 patients (median age 5 years, range 0−15; 59.9% male) was included. Fractures were recorded in 80 (49.4%) and contusions and abrasions in 49 (30.2%) cases. BBR fractures were recorded in 44.8% of children below the age of 3, in 50.8% aged 3−5, in 58.5% aged 6−9 and in 28.6% ≥ 10 years. Forearm fractures were most common (n = 34, 42.5%), followed by fractures of the clavicle (n = 13, 16.3%), humerus (n = 10, 12.5%), foot (n = 8, 10.0%), hand (n = 5, 6.3%), lower leg (n = 5, 6.3%) and skull (n = 5, 6.3%). Surgery was required in 12 (15.0%) cases, including closed reduction (n = 7) and closed reduction with internal fixation (n = 5). Overall, 21 (26.3%) patients were hospitalized with a mean length of stay of 2 ± 1.6 days. Conclusions: Caregivers should be aware that bunk beds cause a significant amount of severe trauma in children and adolescents, especially in those younger than 10 years of age. Caregivers would benefit from receiving information about these risks and evidence-based strategies to prevent BBR fractures.

[Personality Models in the Context of Child and Adolescent Psychiatry - Development, Change, Stability and Research Perspectives]. / Persönlichkeitsmodelle im Kontext der Kinder- und Jugendpsychiatrie ­ Entwicklung, Veränderung, Stabilität und Forschungsperspektiven.

Personality models play an important role for the etiological understanding of abnormal development in clinical settings. In this selective review, relevant personality models are presented and, in particular, their developmental dynamics and adaptability over the life span, starting in childhood, are considered in detail. The focus is on the developmental psychopathological perspective of processes of ego-resiliency and self-regulation between the poles of disposition and social environment. This is particularly obvious in the discussion of developmental path models of personality dysfunction with experiences of abuse or disorganized attachment in the child's history. Psychopathologically, an ongoing impairment of self-regulation often results in stable patterns of maladaptation, which leads in the case of purely symptomatic treatment usually only to temporary behavioral modifications. On the other hand, the changeability of pathological personality traits through the use of targeted intervention approaches will favour of a positive outcome and contradicts a deterministic stability of personality characteristics. For future research perspectives in developmental psychopathology, various theoretical personality constructs are discussed and linked to clinical observations.

Hepatitis B virus core protein phosphorylation: Identification of the SRPK1 target sites and impact of their occupancy on RNA binding and capsid structure.

Hepatitis B virus (HBV) replicates its 3 kb DNA genome through capsid-internal reverse transcription, initiated by assembly of 120 core protein (HBc) dimers around a complex of viral pregenomic (pg) RNA and polymerase. Following synthesis of relaxed circular (RC) DNA capsids can be enveloped and secreted as stable virions. Upon infection of a new cell, however, the capsid disintegrates to release the RC-DNA into the nucleus for conversion into covalently closed circular (ccc) DNA. HBc´s interactions with nucleic acids are mediated by an arginine-rich C terminal domain (CTD) with intrinsically strong non-specific RNA binding activity. Adaptation to the changing demands for nucleic acid binding during the viral life cycle is thought to involve dynamic phosphorylation / dephosphorylation events. However, neither the relevant enzymes nor their target sites in HBc are firmly established. Here we developed a bacterial coexpression system enabling access to definably phosphorylated HBc. Combining Phos-tag gel electrophoresis, mass spectrometry and mutagenesis we identified seven of the eight hydroxy amino acids in the CTD as target sites for serine-arginine rich protein kinase 1 (SRPK1); fewer sites were phosphorylated by PKA and PKC. Phosphorylation of all seven sites reduced nonspecific RNA encapsidation as drastically as deletion of the entire CTD and altered CTD surface accessibility, without major structure changes in the capsid shell. The bulk of capsids from human hepatoma cells was similarly highly, yet non-identically, phosphorylated as by SRPK1. While not proving SRPK1 as the infection-relevant HBc kinase the data suggest a mechanism whereby high-level HBc phosphorylation principally suppresses RNA binding whereas one or few strategic dephosphorylation events enable selective packaging of the pgRNA/polymerase complex. The tools developed in this study should greatly facilitate the further deciphering of the role of HBc phosphorylation in HBV infection and its evaluation as a potential new therapeutic target.

Trauma, treatment and Tetris: video gaming increases hippocampal volume in male patients with combat-related posttraumatic stress disorder.

Background: Tetris has been proposed as a preventative intervention to reduce intrusive memories of a traumatic event. However, no neuroimaging study has assessed Tetris in patients with existing posttraumatic stress disorder (PTSD) or explored how playing Tetris may affect brain structure. Methods: We recruited patients with combat-related PTSD before psychotherapy and randomly assigned them to an experimental Tetris and therapy group (n = 20) or to a therapy-only control group (n = 20). In the control group, participants completed therapy as usual: eye movement desensitization and reprocessing (EMDR) psychotherapy. In the Tetris group, in addition to EMDR, participants also played 60 minutes of Tetris every day from onset to completion of therapy, approximately 6 weeks later. Participants completed structural MRI and psychological questionnaires before and after therapy, and we collected psychological questionnaire data at follow-up, approximately 6 months later. We hypothesized that the Tetris group would show increases in hippocampal volume and reductions in symptoms, both directly after completion of therapy and at follow-up. Results: Following therapy, hippocampal volume increased in the Tetris group, but not the control group. As well, hippocampal increases were correlated with reductions in symptoms of PTSD, depression and anxiety between completion of therapy and follow-up in the Tetris group, but not the control group. Limitations: Playing Tetris may act as a cognitive interference task and as a brain-training intervention, but it was not possible to distinguish between these 2 potential mechanisms. Conclusion: Tetris may be useful as an adjunct therapeutic intervention for PTSD. Tetris-related increases in hippocampal volume may ensure that therapeutic gains are maintained after completion of therapy.

Phenotypic and functional differences of HBV core-specific versus HBV polymerase-specific CD8+ T cells in chronically HBV-infected patients with low viral load.

OBJECTIVE: A hallmark of chronic HBV (cHBV) infection is the presence of impaired HBV-specific CD8+ T cell responses. Functional T cell exhaustion induced by persistent antigen stimulation is considered a major mechanism underlying this impairment. However, due to their low frequencies in chronic infection, it is currently unknown whether HBV-specific CD8+ T cells targeting different epitopes are similarly impaired and share molecular profiles indicative of T cell exhaustion. DESIGN: By applying peptide-loaded MHC I tetramer-based enrichment, we could detect HBV-specific CD8+ T cells targeting epitopes in the HBV core and the polymerase proteins in the majority of 85 tested cHBV patients with low viral loads. Lower detection rates were obtained for envelope-specific CD8+ T cells. Subsequently, we performed phenotypic and functional in-depth analyses. RESULTS: HBV-specific CD8+ T cells are not terminally exhausted but rather exhibit a memory-like phenotype in patients with low viral load possibly reflecting weak ongoing cognate antigen recognition. Moreover, HBV-specific CD8+ T cells targeting core versus polymerase epitopes significantly differed in frequency, phenotype and function. In particular, in comparison with core-specific CD8+ T cells, a higher frequency of polymerase-specific CD8+ T cells expressed CD38, KLRG1 and Eomes accompanied by low T-bet expression and downregulated CD127 indicative of a more severe T cell exhaustion. In addition, polymerase-specific CD8+ T cells exhibited a reduced expansion capacity that was linked to a dysbalanced TCF1/BCL2 expression. CONCLUSIONS: Overall, the molecular mechanisms underlying impaired T cell responses differ with respect to the targeted HBV antigens. These results have potential implications for immunotherapeutic approaches in HBV cure.

German research perspectives on suicidality and the rationale for future multinational suicide prevention projects among military service personnel.

As a result of scientific publications indicating that the last two decades have seen an increase in the number of suicides in the US Armed Forces, the topic of suicide in the military of other countries, such as Germany, has also received a lot of attention in media and science alike. Risk factors for suicidal behaviour and suicide were identified in several research projects in the US, Canada, the UK, and Germany. Until now, German suicide research among military service personnel has mainly focused on epidemiological aspects of suicides and suicidality, individual risk factors, sub-groups at risk for suicide, suicides and deployment abroad, and associations of suicide and suicide attempts with acute mental disorders. The key findings are summarized in this review article. Efforts should be made to develop and evaluate risk group-focused and occupation-focused prevention and intervention programs. Future multinational studies should address potential differences between risk groups for fatal and non-fatal suicidal behaviour.

[Mental Health Stigma: An Influencing Factor in Healthcare Utilization by Veterans of the German Armed Forces]. / "Treffer im Kopf" ­ Stigma psychischer Erkrankungen als Einflussfaktor auf die Inanspruchnahme von Hilfsangeboten durch VeteranInnen der Bundeswehr.

THEORETICAL BACKGROUND AND OBJECTIVE OF THE STUDY: Mental illness stigma is a barrier to healthcare utilization. This study is the first to research the connection between mental illness stigma and the use of healthcare by veterans of the German Armed Forces. An overview of perceived stigma components in this sample is provided that should help understand how these factors influence healthcare utilization. METHODS: 43 interviews with veterans of the German Armed Forces were conducted. The resulting data were analyzed in several coding steps. It was investigated whether the stigma experience of veterans of the German Armed Forces could be well illustrated by the theory-based stigmatization model of Link and Phelan. A set of hypotheses on stigma and healthcare utilization based on the data were developed. RESULTS: All stigma components according to the model of Link and Phelan were found in the sample. Internalized stigma, perceived public stigmatization, vocational disadvantage and social exclusion as well as feared misunderstanding of the military past in the civilian sector were reported as main stigma-relevant barriers to the use of healthcare. CONCLUSIONS: Recommendations for interventions are given to decrease mental illness stigma in this specific group of former soldiers.

Attachment Disorder behavior in early and middle childhood: associations with children's self-concept and observed signs of negative internal working models.

Most research on attachment in childhood is based on observation. In contrast, research on reactive attachment disorder (RAD) is mainly based on caregiver reports. Moreover, little is known about self-concept or internal working models (IWMs) of self and others in children with RAD. The present study examined whether caregiver reports and the frequency of observed signs of RAD reveal differences between children at risk for developing RAD symptoms and healthy controls in middle childhood. In addition, children's self-concept, observable signs of negative IWMs, and mental health were assessed. Results revealed that the RAD risk group showed increased reported and observed signs of RAD, a more negative self-concept, and more signs of negative IWMs compared to healthy controls. Signs of RAD in middle childhood were expressed trans-relational to both caregivers and strangers. Moreover, RAD symptoms were associated with negative self-concept, observed signs of negative IWMs, and poor mental health.

Recent contributions for understanding Inhibited Reactive Attachment Disorder.

This special issue brings together studies representing the current state of the art research on inhibited reactive attachment disorder (RAD) from developmental psychology and developmental attachment research. This editorial introduces and discusses conceptual topics of the development and  the assessment of inhibited RAD. Next, five empirical studies of this special issue cover timely topics from developmental trajectories and longitudinal stability of RAD to associations with caregiving experiences in institutions, IQ, and psychopathology, moreover aspects of internal working models of children with inhibited RAD are examined. The commentary meta-analytically integrates the empirical evidence of all five studies and offers theoretically derived suggestions for further research. In this editorial, we discuss unsettled issues and future directions for attachment oriented research in this field.

[Intervention programs for psychological stress in children of military personnel in the USA - Results of a systematic literature review with regard to transferability to Germany]. / Interventionsprogramme bei psychischen Belastungen von Kindern von Militärangehörigen in den USA.

Intervention programs for psychological stress in children of military personnel in the USA - Results of a systematic literature review with regard to transferability to Germany Abstract. Military personnel who have been deployed in war zones or other unstable regions are at an increased risk to develop mental health disorders, including posttraumatic stress disorder. Likewise, their children are at high risk to develop mental health problems as well as emotional and behavioral difficulties. Most research on prevalence of mental health problems as well as on interventions within this group was conducted in the USA. In Germany, no systematic intervention for children of military members focusing on their experiences of deployment exist. The systematic literature review aimed to analyze existing intervention programs in the USA, in particular for children of military members regarding evidence, type and addressed target group (parents, children, both). Compared to the social welfare and health care systems in the USA, the German systems are different. Hence, a second aim was to examine the transferability of these programs to the specific needs of children of German military members (Bundeswehr). 27 intervention programs could be included in the review. Programs, directly or indirectly, are addressing the needs of children of a deployed parent. They are usually focusing on the "emotional cycle of deployment" (phase of preparation of deployment, separation phase of deployment and the return of the deployed parent). The programs mainly focused on parenting skills, family reactions to stress, coping strategies of families, and the feeling of coherence within the family. Only 20 % of the interventions could be assigned to the type of indicated prevention. Nine interventions have shown positive effects (either in RCT or non-experimental designs). Several elements of the programs are transferable to the German situation of children of military members. In particular, contents which address the specific situation of families with a military member are desperately needed in Germany. Transferability is limited by the non-comparability of health care and social welfare systems in the USA and in Germany.

Challenges for Research into Military Investigations.

In cases of suspected violations of rules, regulations or the law by armed forces personnel, investigations are invariably mandatory. Military investigations differ from well-researched civilian criminal investigations. Differing from civilian police detectives, most military investigators - as disciplinary supervisors and military police personnel - have a number of tasks to accomplish, which include leading in combat and ensuring military readiness. Military investigations can lead to substantive negative or positive consequences for military readiness, including mental health, unit cohesion and subjective legal certainty. This impact on unit cohesion and mental health is influenced by any prior history of distress or trauma; military investigations are often preceded by contravention of internal disciplinary acts, complaints and traumatic events. This study explores factors in the differing military and legal systems of Germany and the United Kingdom (UK) that might help military personnel to successfully conduct investigations while ensuring deployment readiness and maintaining human rights.

[German Military Families: A Qualitative Inquiry of Strategies of Coping with the Fathers' Absence]. / Kinder deutscher Soldatenfamilien: Qualitative Untersuchung zu Strategien im Umgang mit der Abwesenheit des Vaters.

German Military Families: A Qualitative Inquiry of Strategies of Coping with the Fathers' Absence Military families with experiences of deployment are subject to multiple stressors. In this research an explorative qualitative design was used to identify specific challenges, resources and strategies of coping within the families, focusing on the children's perspective. Results show that the fathers' absence causes vital changes in the family system, which demand specific strategies to deal with the abrupt emotional and social challenges. Four of these coping strategies will be presented in this article. Furthermore, resources embedded in the social environment as well as supportive structures provided by the German military will be discussed. Two hypotheses were formulated to outline the findings that the preparation for a deployment as well as patterns of communication about the father's absence are the most crucial factors for the children's resilience in the case of military families.

Active Potentiometry for Dissolved Oxygen Monitoring with Platinum Electrodes.

Potentiometric oxygen monitoring using platinum as the electrode material was enabled by the combination of conventional potentiometry with active prepolarization protocols, what we call active potentiometry. The obtained logarithmic transfer function is well-suited for the measurement of dissolved oxygen in biomedical applications, as the physiological oxygen concentration typically varies over several decades. We describe the application of active potentiometry in phosphate buffered salt solution at different pH and ion strength. Sensitivity was in the range of 60 mV/dec oxygen concentration; the transfer function deviated from logarithmic behavior for smaller oxygen concentration and higher ion strength of the electrolyte. Long-term stability was demonstrated for 60 h. Based on these measurement results and additional cyclic voltammetry investigations a model is discussed to explain the potential forming mechanism. The described method of active potentiometry is applicable to many different potentiometric sensors possibly enhancing sensitivity or selectivity for a specific parameter.

[Personality Assessment as Contribution to Diagnostic Differentiation Between ADHD and RAD in Middle Childhood]. / Persönlichkeitserfassung als Beitrag zur Differentialdiagnostik zwischen Patienten mit ADHS und Bindungsstörung in der mittleren Kindheit.

Personality Assessment as Contribution to Diagnostic Differentiation Between ADHD and RAD in Middle Childhood Early and prolonged social and emotional deprivation can result in symptoms of both ADHD and attachment disorder (RAD). The present study compares children between 7 and 13 years of age diagnosed with either ADHD or RAD, regarding their disorder specific behavior by using the Conners Rating Scale, a RAD screening scale, the overall psychopathology in the CASCAP-D, and the children's personality using the California Child-Q-sort (CCQ). The RAD group showed an increased overall psychopathology score and both increased ADHD and RAD symptomatology. In addition, they also were characterized as lower in self-regulatory personality characteristics (e. g. ego-resiliency). The results suggest that children with a RAD diagnosis do not show two comorbid disorders (RAD plus ADHD) but are characterized by an even more intense deficit of self-regulation in social and emotional contexts, compared to the children of the pure ADHD group. This should be considered in diagnosis and treatment.

[Observation of Attachment Disorder Symptoms in Middle Childhood]. / Beobachtung von Bindungsstörungssymptomen in der mittleren Kindheit.

Observation of Attachment Disorder Symptoms in Middle Childhood Attachment in childhood is mainly assessed by observation. In contrast, assessment of attachment disorder symptoms (RAD) is mainly based on caregiver reports. The present study uses a newly developed observation tool (Coding of Attachment Disorder Behavior in Children; Iwanski u. Zimmermann, 2013) to assess attachment disorder symptoms in a group of school-aged children from a risk group for the development of attachment disorder symptoms and non-clinical controls. In addition, caregiver reports on RAD symptoms are also assessed (Relationship Problems Questionnaire; Minnis, Rabe-Hesketh, Wolkind, 2002; Disturbances of Attachment Interview; Smyke u. Zeanah, 1999). Moreover, associations with children's self-concept (Harter, 2012) were studied. Results reveal that children at risk showed more inhibited and disinhibited attachment disorder symptoms and a more negative self-concept compared to non-clinical controls. RAD symptoms are shown in interaction with both the caregiver and a stranger. The use of a reliable and valid observation tool for the diagnostic of attachment disorder symptoms besides ratings of caregivers is recommended for clinical practice and research.

Sleep quality of German soldiers before, during and after deployment in Afghanistan-a prospective study.

In this prospective study, subjective sleep quality and excessive daytime sleepiness prior to, during and after deployment of German soldiers in Afghanistan were examined. Sleep quality (Pittsburgh Sleep Quality Index; PSQI) and daytime sleepiness (Epworth Sleepiness Scale; ESS) were assessed in 118 soldiers of the German army, who were deployed in Afghanistan for 6 months (deployment group: DG) and in 146 soldiers of a non-deployed control group (CG) at baseline. Results of the longitudinal analysis are reported, based on assessments conducted prior to, during the deployment and afterwards in the DG, and in the CG in parallel. Sleep quality and daytime sleepiness in the DG were already impaired during the predeployment training phase and remained at that level during the deployment phase, which clearly indicates the need for more attention on sleep in young soldiers, already at this early stage. The percentage of impaired sleepers decreased significantly after deployment. Programmes to teach techniques to improve sleep and reduce stress should be implemented prior to deployment to reduce sleep difficulties and excessive daytime sleepiness and subsequent psychiatric disorders.

Iron L-Edge Absorption Spectroscopy of Iron Pentacarbonyl and Ferrocene in the Gas Phase.

Fe L-edge X-ray absorption spectra of gas-phase iron pentacarbonyl and ferrocene measured in total-ion yield mode are reported. Comparison to previously published spectra of free iron atoms and gaseous iron chloride demonstrates how the interplay of local atomic multiplet effects and orbital interactions in the metal-ligand bonds varies for the different systems. We find changes in the degree of metal-ligand covalency to be reflected in the measured 2p absorption onset. Orbital- or state-specific fragmentation is furthermore investigated in iron pentacarbonyl and ferrocene by analyzing the partial-ion-yield spectra at the Fe L-edge. Strong dependence of the yields of different fragments is observed in ferrocene in contrast to iron pentacarbonyl. This difference is attributed to the different degrees to which the 2p core hole is screened in the two systems and to which charge is rearranged in the Auger final states. We provide experimental benchmark spectra for new ab initio approaches for calculating metal L-edge absorption spectra of metal complexes.