Perfluorierte Ionische Flüssigkeiten und hexanukleare Niobcluster

Im Rahmen dieser Arbeit wurden neue Cluster-Verbindungen des Metalls Niob mit hexanuclearen Metalleinheiten untersucht. Sowohl neutrale Cluster-Verbindungen der allgemeinen Formel [Nb6Cli12Cla2(L)a4}] mit L = DCU, Py, HMIm, IBA, als auch ein erster Vertreter eines neuen Nb6-Cluster-Verbindungstyps mit intramolekularen Chelatliganden mit der Formel [Nb6(OCH2CH2NH2)i-a6(OCH2CH2NH2)i6]3+ 3[I]-. Des Weiteren wurden Verbindungen mit der Formel [A]4[Nb6Cli12(L)a6] mit A = TMG, TPA, Py, HMIm und L = TFA, PFP und HFB synthetisiert. Diese Verbindungen wurden chemisch vollständig charakterisiert.In this work new cluster compounds of the metal niobium with hexanuclear metal units were investigated. Both neutral cluster compounds of the general formula [Nb6Cli12Cla2 (L) a4}] with L = DCU, Py, HMIm, IBA, and a first representative of a new Nb6 cluster compound type with intramolecular chelating ligands of the formula [Nb6 (OCH2CH2NH2) i-a6 (OCH2CH2NH2) i6] 3+ 3 [I] -. Furthermore, compounds with the formula [A] 4 [Nb6Cli12 (L) a6] with A = TMG, TPA, Py, HMIm and L = TFA, PFP and HFB were synthesized. These compounds have been fully chemically characterized

Extending an Open-Source Federated Identity Management System for Enhanced HPC Security

Strengthening the security infrastructure around HPC systems has become an urgent and important task, driven especially by the impact of a recent large-scale attack on the world-wide HPC community by a yet unknown party. Multiple European HPC systems had to be shut down for several weeks in mid-May of 2020 after backdoors were found on the systems. In the aftermath of the attack, two core security issues were identified: the absence of strong authentication, and a wide-spread practice of insecure handling of SSH key pairs. We present our approach for extending an existing, open source, federated identity management system with user-friendly two-factor authentication (2FA) using Time-Based One-Time Password (TOTP) and centralized, secure SSH key management. A special focus will be put on how we integrated scientific workflows and automation with the new security measures by combining 2FA, SSH key management and security policies in an elegant, secure and user-friendly way

Twitter Users’ Privacy Behavior: A Reasoned Action Approach

Social networking sites have become a predominant means of communication across the globe. Activities on these sites generate massive amounts of personal information and raise concerns about its potential abuse. Means designed to protect the user’s privacy and prevent exploitation of confidential data often go unused. In this study, we draw on the theory of planned behavior, a reasoned action approach, to explain intentions to adopt privacy behaviors on social networking sites, with a focus on Twitter users. Consistent with the theory, an online survey of Twitter users ( n = 1,060) found that instrumental and experiential attitudes and descriptive and injunctive subjective norms regarding these behaviors were direct predictors of intentions. Perceived behavioral control had a moderating effect, such that subjective norm was a better predictor of intentions for participants high as opposed to low in perceived control. We briefly discuss the implications of these results for developing theory-driven and evidence-based interventions to promote privacy behavior

Syntactic development in early foreign language learning: Effects of L1 transfer, input and individual factors

This study explores parallels and differences in the comprehension of wh-questions and relative clauses between early foreign-language (FL) learners and monolingual children. We test for (a) effects of syntactic first-language (L1) transfer, (b) the impact of input on syntactic development, and (c) the impact of individual differences on early FL syntactic development. We compare the results to findings in child second language (L2) naturalistic acquisition and adult FL acquisition. Following work on adult FL acquisition, we carried out a picture-based interpretation task with 243 child FL learners in fourth grade at different regular, partial, and high-immersion schools in Germany plus 68 monolingual English children aged 5 to 8 years as controls. The child FL learners display a strong subject-first preference but do not appear to use the L1 syntax in comprehension. Input differences across different schools affect overall accuracy, with students at high-immersion FL schools catching up to monolingual performance within 4 years of learning. Finally, phonological awareness is implicated in both early FL learning and naturalistic child L2 development. These findings suggest that early FL development resembles child L2 acquisition in speed and effects of individual factors, yet is different from adult FL acquisition due to the absence of L1 transfer effects.Peer reviewedFinal Accepted Versio

Combined Coronary CT-Angiography and TAVI-Planning: A Contrast-Neutral Routine Approach for Ruling-Out Significant Coronary Artery Disease

Background: Significant coronary artery disease (CAD) is a common finding in patients undergoing transcatheter aortic valve implantation (TAVI). Assessment of CAD prior to TAVI is recommended by current guidelines and is mainly performed via invasive coronary angiography (ICA). In this study we analyzed the ability of coronary CT-angiography (cCTA) to rule out significant CAD (stenosis ≥ 50%) during routine pre-TAVI evaluation in patients with high pre-test probability for CAD. Methods: In total, 460 consecutive patients undergoing pre-TAVI CT (mean age 79.6 ± 7.4 years) were included. All patients were examined with a retrospectively ECG-gated CT-scan of the heart, followed by a high-pitch-scan of the vascular access route utilizing a single intravenous bolus of 70 mL iodinated contrast medium. Images were evaluated for image quality, calcifications, and significant CAD; CT-examinations in which CAD could not be ruled out were defined as positive (CAD+). Routinely, patients received ICA (388/460; 84.3%; Group A), which was omitted if renal function was impaired and CAD was ruled out on cCTA (Group B). Following TAVI, clinical events were documented during the hospital stay. Results: cCTA was negative for CAD in 40.2% (188/460). Sensitivity, specificity, PPV, and NPV in Group A were 97.8%, 45.2%, 49.6%, and 97.4%, respectively. Median coronary artery calcium score (CAC) was higher in CAD+-patients but did not have predictive value for correct classification of patients with cCTA. There were no significant differences in clinical events between Group A and B. Conclusion: cCTA can be incorporated into pre-TAVI CT-evaluation with no need for additional contrast medium. cCTA may exclude significant CAD in a relatively high percentage of these high-risk patients. Thereby, cCTA may have the potential to reduce the need for ICA and total amount of contrast medium applied, possibly making pre-procedural evaluation for TAVI safer and faster

Exhaled Aerosols in SARS-CoV-2 Polymerase Chain Reaction-Positive Children and Age-Matched-Negative Controls

BackgroundChildren and adolescents seem to be less affected by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease in terms of severity, especially until the increasing spread of the omicron variant in December 2021. Anatomical structures and lower number of exhaled aerosols may in part explain this phenomenon. In a cohort of healthy and SARS-CoV-2 infected children, we compared exhaled particle counts to gain further insights about the spreading of SARS-CoV-2.Materials and MethodsIn this single-center prospective observational trial, a total of 162 children and adolescents (age 6–17 years), of whom 39 were polymerase chain reaction (PCR)-positive for SARS-CoV-2 and 123 PCR-negative, were included. The 39 PCR-positive children were compared to 39 PCR-negative age-matched controls. The data of all PCR-negative children were analyzed to determine baseline exhaled particle counts in children. In addition, medical and clinical history was obtained and spirometry was measured.ResultsBaseline exhaled particle counts were low in healthy children. Exhaled particle counts were significantly increased in SARS-CoV-2 PCR-positive children (median 355.0/L; range 81–6955/L), compared to age-matched -negative children (median 157.0/L; range 1–533/L; p < 0.001).ConclusionSARS-CoV-2 PCR-positive children exhaled significantly higher levels of aerosols than healthy children. Overall children had low levels of exhaled particle counts, possibly indicating that children are not the major driver of the SARS-CoV-2 pandemic.Trial Registration[ClinicalTrials.gov], Identifier [NCT04739020]

Biomonitoring of polycyclic aromatic hydrocarbons in firefighters at fire training facilities and in employees at respiratory protection and hose workshops

IntroductionPolycyclic aromatic hydrocarbons (PAHs) are carcinogenic to humans and are formed by incomplete combustion. PAHs are always present during firefighting operations, and fire department members can be exposed to them in the workplace.MethodsIn this study, we analyzed 1-hydroxypyrene (1-OHP) in 36 urine samples from nine firefighters, collected before and after fire training sessions, and 32 urine samples from eight employees at respiratory protection and hose workshops. To assess breakthrough PAH exposure through personal protective equipment and potential dermal uptake, some of the workshop employees wore cotton garments under their regular workwear. Cotton samples were then examined for the presence of 17 semi-volatile and low-volatility PAHs.ResultsAfter firefighting exercises, we observed approximately a fivefold increase in mean 1-OHP concentrations in samples from firefighters, from 0.24 μg/L to 1.17 μg/L (maximum: 5.31 μg/L). In contrast, 1-OHP levels in workshop employees were found to be low, with the majority of urine samples yielding concentrations below the limit of quantification (LOQ: 0.05 μg/L, maximum: 0.11 μg/L). Similarly, low PAH levels were found on the workshop employees' cotton undergarments, with maximum concentrations of 250 and 205 ng/g for pyrene and benzo[a]pyrene, respectively.DiscussionIn conclusion, significant increases in 1-OHP in urine were observed in firefighters after training sessions, whereas work-related exposure remained low among workshop employees

The effect of phosphatidylserine on golf performance

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

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