Ionothermal Synthesis of Imide-Linked Covalent Organic Frameworks

Covalent organic frameworks (COFs) are an extensively studied class of porous materials, which distinguish themselves from other porous polymers in their crystallinity and high degree of modularity, enabling a wide range of applications. COFs are most commonly synthesized solvothermally, which is often a time‐consuming process and restricted to well‐soluble precursor molecules. Synthesis of polyimide‐linked COFs (PI‐COFs) is further complicated by the poor reversibility of the ring‐closing reaction under solvothermal conditions. Herein, we report the ionothermal synthesis of crystalline and porous PI‐COFs in zinc chloride and eutectic salt mixtures. This synthesis does not require soluble precursors and the reaction time is significantly reduced as compared to standard solvothermal synthesis methods. In addition to applying the synthesis to previously reported imide COFs, a new perylene‐based COF was also synthesized, which could not be obtained by the classical solvothermal route. In situ high‐temperature XRPD analysis hints to the formation of precursor–salt adducts as crystalline intermediates, which then react with each other to form the COF

Tailor-Made Photoconductive Pyrene-Based Covalent Organic Frameworks for Visible-Light Driven Hydrogen Generation

Covalent organic frameworks (COFs) have emerged as a new class of crystalline porous polymers displaying molecular tunability combined with structural definition. Here, a series of three conjugated, photoactive azine-linked COFs based on pyrene building blocks which differ in the number of nitrogen atoms in the peripheral aromatic units is presented. The structure of the COFs is analyzed by combined experimental and computational physisorption as well as quantum-chemical calculations, which suggest a slipped-stacked arrangement of the 2D layers. Photocurrents of up to 6 mu A cm(-2) with subsecond photoresponse times are measured on thin film samples for the first time. While all COFs are capable of producing hydrogen from water, their efficiency increases significantly with decreasing number of nitrogen atoms. The trending activities are rationalized by photoelectrochemical measurements and quantum-chemical calculations which suggest an increase in the thermodynamic driving force with decreasing nitrogen content to be the origin of the observed differences in hydrogen evolution activities

Environmentally relevant concentrations of triclocarban affect behaviour, learning, and brain gene expression in fish

Many chemicals spilled in aquatic ecosystems can interfere with cognitive abilities and brain functions that control fitness-related behaviour. Hence, their harmful potential may be substantially underestimated. Triclocarban (TCC), one of the most common aquatic contaminants, is known to disrupt hormonal activity, but the consequences of this action on behaviour and its underlying cognitive mechanisms are unclear. We tried to fill this knowledge gap by analysing behaviour, cognitive abilities, and brain gene expression in zebrafish larvae exposed to TCC sublethal concentrations. TCC exposure substantially decreased exploratory behaviour and response to stimulation, while it increased sociability. Additionally, TCC reduced the cognitive performance of zebrafish in a habituation learning task. In the brain of TCC-exposed zebrafish, we found upregulation of c-fos, a gene involved in neural activity, and downregulation of bdnf, a gene that influences behavioural and cognitive traits such as activity, learning, and memory. Overall, our experiments highlight consistent effects of non-lethal TCC concentrations on behaviour, cognitive abilities, and brain functioning in a teleost fish, suggesting critical fitness consequences of these compounds in aquatic ecosystems as well as the potential to affect human health

Early-life exposure to environmentally relevant concentrations of triclocarban impairs ocular development in zebrafish larvae

Triclocarban (TCC), is an antimicrobial component in personal care products and it is one of the emerging contaminants since it has been detected in various environmental matrices. Its presence in human cord blood, breast milk, and maternal urine raised issues about its possible impact on development and increased concerns about the safety of daily exposure. This study aims to provide additional information about the effects of zebrafish early-life exposure to TCC on eye development and visual function. Zebrafish embryos were exposed to two concentrations of TCC (5 and 50 μg/L) for 4 days. TCC-mediated toxicity was assessed in larvae at the end of exposure and in the long term (20 days post fertilization; dpf), through different biological end-points. The experiments showed that TCC exposure influences the retinal architecture. In 4 dpf treated larvae, we found a less organized ciliary marginal zone, a decrease in the inner nuclear and inner plexiform layers, and a decrease in the retinal ganglion cell layer. Photoreceptor and inner plexiform layers showed an increase in 20 dpf larvae at lower and both concentrations, respectively. The expression levels of two genes involved in eye development (mitfb and pax6a) were both decreased at the concentration of 5 μg/L in 4 dpf larvae, and an increase in mitfb was observed in 5 μg/L-exposed 20 dpf larvae. Interestingly, 20 dpf larvae failed to discriminate between visual stimuli, demonstrating notable visual perception impairments due to compound. The results prompt us to hypothesize that early-life exposure to TCC may have severe and potentially long-term effect on zebrafish visual function

Modular Assembly of Vibrationally and Electronically Coupled Rhenium Bipyridine Carbonyl Complexes on Silicon

Hybrid inorganic/organic heterointerfaces are promising systems for next-generation photocatalytic, photovoltaic, and chemical-sensing applications. Their performance relies strongly on the development of robust and reliable surface passivation and functionalization protocols with (sub)molecular control. The structure, stability, and chemistry of the semiconductor surface determine the functionality of the hybrid assembly. Generally, these modification schemes have to be laboriously developed to satisfy the specific chemical demands of the semiconductor surface. The implementation of a chemically independent, yet highly selective, standardized surface functionalization scheme, compatible with nanoelectronic device fabrication, is of utmost technological relevance. Here, we introduce a modular surface assembly (MSA) approach that allows the covalent anchoring of molecular transition-metal complexes with sub-nanometer precision on any solid material by combining atomic layer deposition (ALD) and selectively self-assembled monolayers of phosphonic acids. ALD, as an essential tool in semiconductor device fabrication, is used to grow conformal aluminum oxide activation coatings, down to sub-nanometer thicknesses, on silicon surfaces to enable a selective step-by-step layer assembly of rhenium(I) bipyridine tricarbonyl molecular complexes. The modular surface assembly of molecular complexes generates precisely structured spatial ensembles with strong intermolecular vibrational and electronic coupling, as demonstrated by infrared spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy analysis. The structure of the MSA can be chosen to avoid electronic interactions with the semiconductor substrate to exclusively investigate the electronic interactions between the surface-immobilized molecular complexes

Infections in travellers returning to Turkey from the Arabian peninsula: a retrospective cross-sectional multicenter study

WOS: 000377022000004PubMed ID: 26964538Mass gatherings pooling people from different parts of the world-the largest of which is to Mecca, Saudi Arabia, for Hajj-may impose risks for acquisition and dissemination of infectious diseases. A substantial number of pilgrims to Hajj and Umrah are Turkish citizens (456,000 in 2014) but data are lacking on scale of the problem. We did a retrospective cross-sectional multicenter study in Turkey to explore the range of infections among inpatients who had recently returned from the Arabian Peninsula. Our inclusion criteria were patients who had acquired an infection during their trip to an Arabian Peninsula country, or who became symptomatic within 1 week of their return. The data were collected retrospectively for January 1, 2013 and March 1, 2015. 185 Turkish patients were recruited to the study across 15 referral centers with travel associated infectious diseases after returning from Arabian Peninsula countries (predominantly Saudi Arabia 163 [88.1 %] for religious purposes 162 [87.5 %]). Seventy four (40.0 %) of them were a parts per thousand yen 65 years old with numerous comorbidities including diabetes (24.3 %) and COPD (14.1 %). The most common clinical diagnosis was respiratory tract infections (169 [91.5 %]), followed by diarrheal diseases (13 [7 %]), and there was one case of MERS-CoV. Patients spent a median of 5 (3-7) days as hospital inpatients and overall mortality was 1.1 %. Returning travellers from the Arabian Peninsula present as inpatients with a broad range of infectious diseases similar to common community acquired infections frequently seen in daily medical practices in Turkey

Management of Brucella endocarditis: Results of the Gulhane study

PubMed ID: 22727531Brucella endocarditis (BE) is a rare but life-threatening complication of human brucellosis. The aim of this study was to investigate the course of BE along with the therapeutic interrelations. A total of 53 patients with BE hospitalised in 19 health institutions between 2006 and 2011 were included in the Gulhane study. Diagnosis of brucellosis was established by either isolation of Brucella sp. or the presence of antibodies, and the definition of endocarditis was made according to Duke's criteria. There were four treatment groups: ceftriaxone combined with oral antibiotics (Group 1); aminoglycosides combined with oral antibiotics (Group 2); oral antibiotic combinations (Group 3); and aminoglycoside plus ceftriaxone combined with an oral antibiotic (Group 4). Involvement rates of the aortic, mitral and tricuspid valves were 49.1%, 43.4% and 5.7%, respectively. Thirty-two patients (60.4%) had an underlying cardiac valvular problem, including previous prosthetic valve replacement (n = 18). Medical treatment was provided to 32 patients (60.4%), whilst concordant medical and surgical approaches were provided to 21 patients (39.6%). Mortality in Group 1 was 15% (3/20), whilst in Group 2 it was 5.3% (1/19). In Group 3, 25.0% (3/12) of the cases died, whereas none of the cases in Group 4 died. In conclusion, mortality increased 47-fold with pericardial effusion and 25-fold due to congestive heart failure that developed after BE. Although mortality was lower in the aminoglycoside-containing arm (Groups 2 and 4), statistical analysis could not be performed owing to the small number of patients. © 2012 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved