Synthetic Strategies to Extended Aromatic Covalent Organic Frameworks.

π-Conjugated materials are highly attractive owing to their unique optical and electronic properties. Covalent organic frameworks (COFs) offer a great opportunity for precise arrangement of building units in a π-conjugated crystalline matrix and tuning of the properties through choice of functionalities or post-synthetic modification. With this review, we aim at summarizing both the most representative as well as emerging strategies for the synthesis of π-conjugated COFs. We give examples of direct synthesis using large, π-extended building blocks. COFs featuring fully conjugated linkages such as vinylene, pyrazine, and azole are discussed. Then, post-synthetic modification methods that result in the extension of the COF π-system are reviewed. Throughout, mechanistic insights are presented when available. In the context of their utilization as film devices, we conduct a concise survey of the prominent COF layer deposition techniques reported and their aptness for the deposition of fused aromatic systems.

Disability pension and sociodemographic & work-related risk factors among 2.3 million migrants and natives in Finland (2011-2019): a prospective population study.

BACKGROUND: Increasing employment and immigration have been proposed as possible solutions to tackle the problem of the labour force shortage in aging societies. Ensuring sufficient health and work ability among migrants is a key factor in increasing and maintaining their employment. Many studies have found higher disability pension (DP) rates among migrants compared to natives but such studies lack in determining the risk of DP by occupational class and industrial sector. This study explores the risk of DP and the contribution of sociodemographic and work-related factors between migrants and natives in Finland. METHODS: Full-population panel data obtained from the administrative registers of Statistics Finland were used to study 2.3 million individuals aged 25-60 years in 2010. We calculated hazard ratios (HR) and their 95% confidence intervals (CI) to estimate the risk of having a DP in 2011-2019 using Cox proportional hazard models adjusting for different sociodemographic and work-related factors. RESULTS: Compared to natives, migrants had a lower risk of a DP (HR 0.58, 95% CI 0.53-0.63). We found great variation between countries of origin, where compared to natives, migrants from refugee-exporting countries (HR 1.37, 95% CI 1.22-1.53) and other non-European countries (HR 1.30; CI 1.18-1.43) had a higher risk of DP, but migrants from other countries did not differ or had a slightly lower risk of DP than natives. The associations between sociodemographic factors and the risk of DP were very similar between natives and migrants. CONCLUSION: Migrants had a lower risk of a DP than natives except for migrants from outside Europe. The associations between different sociodemographic and work-related factors and the risk of DP were similar between natives and migrants and did not completely explain the differences in the risk of DP.

Does previous sickness absence affect work participation after vocational labour market training? A difference-in-differences propensity score matching approach.

BACKGROUND: Reduced work ability is relatively common among job seekers and it can hinder future labour market attachment. A commonly used measure to increase employability is the use of active labour market programmes. While vocational labour market training (LMT) has been shown to be an effective way to increase work participation among job seekers, there is still uncertainty about how LMT works in different population groups, for example, among persons with a work disability history. METHODS: We used nationally representative Finnish register data on 16 062 LMT participants in 2008-2015 aged 25-59 with a history of sickness absence (SA) and propensity score matched participants without such history. For matching, we used information on sociodemographic and work-related factors. We used difference-in-differences analysis to investigate the differential changes in work participation before and after LMT between those with and those without SA history. RESULTS: Having a history of SA was associated with a lower gain in work participation after LMT, but the magnitude varied by sex, employment history and follow-up time. In women, having a history of SA contributed to 3.9-6.2 percentage points smaller increase in work participation 1-3 years after LMT, depending on the employment history. In men, the corresponding numbers were 2.0-4.3 percentage points. The results were more pronounced if the SA was due to mental disorders. CONCLUSIONS: The results indicate that work disability, especially due to mental disorders, can hamper work participation after LMT and should be considered when planning employment-enhancing measures for job seekers.

Building Blocks and COFs Formed in Concert-Three-Component Synthesis of Pyrene-Fused Azaacene Covalent Organic Framework in the Bulk and as Films.

A three-component synthesis methodology is described for the formation of covalent organic frameworks (COFs) containing extended aromatics. Notably, this approach enables synthesis of the building blocks and COF along parallel reaction landscapes, on a similar timeframe. The use of fragmental building block components, namely pyrene dione diboronic acid as aggregation-inducing COF precursor and the diamines o-phenylenediamine (Ph), 2,3-diaminonaphthalene (Naph), or (1R,2R)-(+)-1,2-diphenylethylenediamine (2Ph) as extending functionalization units in conjunction with 2,3,6,7,10,11-hexahydroxytriphenylene, resulted in the formation of the corresponding pyrene-fused azaacene, i.e., Aza-COF series with full conversion of the dione moiety, long-range order, and high surface area. In addition, the novel three-component synthesis was successfully applied to produce highly crystalline, oriented thin films of the Aza-COFs with nanostructured surfaces on various substrates. The Aza-COFs exhibit light absorption maxima in the blue spectral region, and each Aza-COF presents a distinct photoluminescence profile. Transient absorption measurements of Aza-Ph- and Aza-Naph-COFs suggest ultrafast relaxation dynamics of excited-states within these COFs.

From long-term sickness absence to disability retirement: diagnostic and occupational class differences within the working-age Finnish population.

BACKGROUND: It is well documented that sickness absence is strongly associated with disability retirement. A long-term sickness absence (LTSA) in particular increases the risk of disability retirement, but little is known about the variation of this risk across diagnostic causes. Further, as occupational classes differ in their diagnostic profiles, it is likely that the role of diagnosis in the pathway from LTSA to disability retirement varies between occupational classes. We examined how LTSA of different diagnostic causes predicts all-cause disability retirement and disability retirement due to the same diagnostic group or due to some other diagnostic group than that which caused the LTSA spell in different occupational classes. METHODS: Cox proportional hazards models were used to analyse a 70% random sample of all employed Finns aged 25-62 Finns in 2006 (N = 1,458,288). Disability retirement was followed from 2007 to 2014. The risk of disability retirement was compared between occupational classes with at least one LTSA spell due to musculoskeletal diseases, mental disorders, respiratory diseases, or circulatory diseases and those who had no LTSA spells due to these diagnostic groups during 2005. RESULTS: Those who had LTSA due to musculoskeletal diseases or mental disorders transferred more often to disability retirement due to same diagnostic group, whereas those who had LTSA due to respiratory or circulatory diseases transferred more often to disability retirement due to some other diagnostic group. The largest occupational class differences in all-cause disability retirement were found among those with LTSA due to mental disorders. For men, the hazard ratios (HR) varied from HR 5.70 (95% confidence interval (CI) 5.00-6.52) in upper non-manual employees to 2.70 (95% CI 2.50-2.92) in manual workers. For women, the corresponding HRs were 3.74 (95% CI 3.37-4.14) in upper non-manual employees and 2.32 (95% 2.17-2.50) in manual workers. CONCLUSIONS: The association between LTSA and disability retirement varies between diagnostic groups, and the strength of this association further depends on the person's occupational class and gender.

Covalent Organic Framework Composites: Synthesis and Analytical Applications.

In the recent years, composite materials containing covalent organic frameworks (COFs) have raised increasing interest for analytical applications. To date, various synthesis techniques have emerged that allow for the preparation of crystalline and porous COF composites with various materials. Herein, we summarize the most common methods used to gain access to crystalline COF composites with magnetic nanoparticles, other oxide materials, graphene and graphene oxide, and metal nanoparticles. Additionally, some examples of stainless steel, polymer, and metal-organic framework composites are presented. Thereafter, we discuss the use of these composites for chromatographic separation, environmental remediation, and sensing.

Extraction of Ibuprofen from Natural Waters Using a Covalent Organic Framework.

Ibuprofen is one of the most widely used pharmaceuticals, and due to its inefficient removal by conventional wastewater treatment, it can be found in natural surface waters at high concentrations. Recently, we demonstrated that the TpBD-(CF3)2 covalent organic framework (COF) can adsorb ibuprofen from ultrapure water with high efficiency. Here, we investigate the performance of the COF for the extraction of ibuprofen from natural water samples from a lake, river, and estuary. In general, the complexity of the natural water matrix induced a reduction in the adsorption efficiency of ibuprofen as compared to ultrapure water. The best performance, with over 70% adsorption efficiency, was found in lake water, the sample which featured the lowest pH. According to the theoretical calculations, ibuprofen more favorably interacts with the COF pores in the protonated form, which could partially account for the enhanced adsorption efficiency found in lake water. In addition, we explored the effect of the presence of competing pharmaceuticals, namely, acetaminophen and phenobarbital, on the ibuprofen adsorption as binary mixtures. Acetaminophen and phenobarbital were adsorbed by TpBD-(CF3)2 with low efficiency and their presence led to an increase in ibuprofen adsorption in the binary mixtures. Overall, this study demonstrates that TpBD-(CF3)2 is an efficient adsorbent for the extraction of ibuprofen from natural waters as well.

Tailoring Covalent Organic Frameworks To Capture Water Contaminants.

Covalent organic frameworks (COFs) are attractive materials receiving increasing interest in the literature due to their crystallinity, large surface area, and pore uniformity. Their properties can be tailored towards specific applications by judicious design of COF building blocks, giving access to tailor-made pore sizes and surfaces. In this Concept article, developments in the field of COFs that have allowed these materials to be explored for contaminant adsorption are discussed. Strategies to obtain water-stable materials with highly ordered structures and large surface areas are reviewed. Post-synthetic modification approaches, by which pore surfaces can be tuned to target specific contaminants, are described. Recent advances in COF formulations, crucial for future implementation in adsorption devices, are highlighted. At the end, future challenges which need to be addressed to allow for the deployment of COFs for the capture of water contaminants will be discussed.

Orthogonal Clickable Iron Oxide Nanoparticle Platform for Targeting, Imaging, and On-Demand Release.

A versatile iron oxide nanoparticle platform is reported that can be orthogonally functionalized to obtain highly derivatized nanomaterials required for a wide variety of applications, such as drug delivery, targeted therapy, or imaging. Facile functionalization of the nanoparticles with two ligands containing isocyanate moieties allows for high coverage of the surface with maleimide and alkyne groups. As a proof-of-principle, the nanoparticles were subsequently functionalized with a fluorophore as a drug model and with biotin as a targeting ligand towards tumor cells through Diels-Alder and azide-alkyne cycloaddition reactions, respectively. The thermoreversibility of the Diels-Alder product was exploited to induce the on-demand release of the loaded molecules by magnetic hyperthermia. Additionally, the nanoparticles were shown to target cancer cells through in vitro experiments, as analyzed by magnetic resonance imaging.

Adsorption of Pharmaceutical Pollutants from Water Using Covalent Organic Frameworks.

Capture of pharmaceutical pollutants from water was studied using a novel fluorine-bearing covalent organic framework TpBD-(CF3 )2 , which showed ibuprofen adsorption capacity of 119 mg g-1 at neutral pH. This value is further enhanced at pH 2, highlighting the potential of this class of materials to serve as adsorbents even under harsh conditions. The adsorbed pharmaceutical can be recovered from TpBD-(CF3 )2 in high yield, offering the option of recycling both the adsorbent and the pharmaceutical. The high efficiency of ibuprofen capture as compared to other less lipophilic pharmaceuticals suggests that COFs can be pre-designed for selective capture of contaminants.

Magnetite Nanoparticles for Stem Cell Labeling with High Efficiency and Long-Term in Vivo Tracking.

Superparamagnetic iron oxide nanoparticles (SPIO-PAA), ultrasmall iron oxide nanoparticles (USPIO-PAA), and glucosamine-modified iron oxide nanoparticles (USPIO-PAA-GlcN) were studied as mesenchymal stem cell (MSCs) labels for cell tracking applications by magnetic resonance imaging (MRI). Pronounced differences were found in the labeling performance of the three samples in terms of cellular dose and labeling efficiency. In combination with polylysine, SPIO-PAA showed nonhomogeneous cell internalization, while for USPIO-PAA no uptake was found. On the contrary, USPIO-PAA-GlcN featured high cellular uptake and biocompatibility, and sensitive detection in both in vitro and in vivo experiments was found by MRI, showing that glucosamine functionalization can be an efficient strategy to increase cell uptake of ultrasmall iron oxide nanoparticles by MSCs.

Extraction of photogenerated electrons and holes from a covalent organic framework integrated heterojunction.

Covalent organic frameworks (COFs) offer a strategy to position molecular semiconductors within a rigid network in a highly controlled and predictable manner. The π-stacked columns of layered two-dimensional COFs enable electronic interactions between the COF sheets, thereby providing a path for exciton and charge carrier migration. Frameworks comprising two electronically separated subunits can form highly defined interdigitated donor-acceptor heterojunctions, which can drive the photogeneration of free charge carriers. Here we report the first example of a photovoltaic device that utilizes exclusively a crystalline organic framework with an inherent type II heterojunction as the active layer. The newly developed triphenylene-porphyrin COF was grown as an oriented thin film with the donor and acceptor units forming one-dimensional stacks that extend along the substrate normal, thus providing an optimal geometry for charge carrier transport. As a result of the degree of morphological precision that can be achieved with COFs and the enormous diversity of functional molecular building blocks that can be used to construct the frameworks, these materials show great potential as model systems for organic heterojunctions and might ultimately provide an alternative to the current disordered bulk heterojunctions.

Sequence analysis of sickness absence and disability pension days in 2012-2018 among privately employed white-collar workers in Sweden: a prospective cohort study.

OBJECTIVE: The aim of the study is to explore sequences of sickness absence (SA) and disability pension (DP) days from 2012 to 2018 among privately employed white-collar workers. DESIGN: A 7-year prospective cohort study using microdata from nationwide registers. SETTING: Sweden. PARTICIPANTS: All 1 283 516 privately employed white-collar workers in Sweden in 2012 aged 18-67. METHODS: Sequence analysis was used to describe clusters of individuals who followed similar development of SA and DP net days/year, and multinomial logistic regression to analyse associations between sociodemographic variables and belonging to each observed cluster of sequences. Odds ratios (ORs) and 95% confidence intervals (CIs) were adjusted for baseline sociodemographics. RESULTS: We identified five clusters of SA and DP sequences: (1) 'low or no SA or DP' (88.7% of the population), (2) 'SA due to other than mental diagnosis' (5.2%), (3) 'SA due to mental diagnosis' (3.4%), (4) 'not eligible for SA or DP' (1.4%) and (5) 'DP' (1.2%). Men, highly educated, born outside Sweden and high-income earners were more likely to belong to the first and the fourth cluster (ORs 1.13-4.49). The second, third and fifth clusters consisted mainly of women, low educated and low-income (ORs 1.22-8.90). There were only small differences between branches of industry in adjusted analyses, and many were not significant. CONCLUSION: In general, only a few privately employed white-collar workers had SA and even fewer had DP during the 7-year follow-up. The risk of belonging to a cluster characterised by SA or DP varied by sex, levels of education and income, and other sociodemographic factors.

Contribution of compositional changes in the workforce to sickness absence trends in Finland.

In this study, we assessed whether the long-term decrease in sickness absences in Finland is explained by observed and unobserved compositional changes in the workforce. Utilizing register-based panel data on Finnish wage earners aged 30-62, we examined the annual onset of compensated sickness absence (granted after 10 weekdays) in the period 2005-2016. We applied random effects models adjusting for changes in the observed sociodemographic and occupational characteristics of the study population. We also applied fixed effects models, with corrections of the estimates for cohort ageing, to additionally account for the unobserved time-invariant characteristics of the study population over the years. Of the observed characteristics, increasing educational level partly explained the decreasing trend in sickness absences, and the further contribution of the occupational class was weak. Additionally, accounting for unobserved individual characteristics further explained the decreasing trend in sickness absences among those aged 30-47 years and led to a reverse increasing trend among those aged 48-62 years irrespective of sex and employment sector. Particularly for those over 47 years old, the decrease in sickness absences appeared to be more strongly influenced by compositional changes in characteristics that are established before fully entering the labour market - such as educational level as well as unmeasured individual characteristics that remain unchanged after childhood and early adulthood - than in the work environment or other factors contributing at working age. Sickness absence trends fluctuated during economic cycles, which did not appear to be explained by immediate changes in the observed or unobserved characteristics. Different mechanisms are likely to explain long-term sickness absence trends and trends around economic cycles. Attempts to improve work ability and labour market inclusion in long-term should rely more on increasing educational levels among the workforce and on interventions carried out early during the life course.

Labour market trajectories after part-time sickness absence: a nationwide cohort study from Finland.

OBJECTIVES: The use of part-time sickness absence (pSA) enables return to part-time work from full sickness absence. However, subsequent labour market outcomes of pSA users depend on various individual and work-related characteristics. We investigated labour market paths of private and public sector employees after having a pSA spell. Moreover, we examined individual and work-related factors associated with following them. DESIGN: Longitudinal register-based cohort study. SETTING: Finnish employed population. PARTICIPANTS: 9896 receivers of partial sickness allowance aged 45-56 in the years 2010-2014. OUTCOME: We constructed labour market trajectories based on the proportion of time spent in various labour market statuses measured over 3 years after the end of the pSA spell using multiresponse trajectory analysis. We then examined how different individual and work-related factors were associated with assignment to the different trajectory groups using logistic regression analyses. RESULTS: The majority of the pSA users followed paths where work participation was consistently elevated (Sustained Work group, 40.4%), or only slightly reduced (Slightly Reduced Work group, 31.6%). Moreover, more than 1/10th of the users followed a path where receiving partial work disability benefits became predominant (Partial Work Disability group, 12.5%). The rest followed paths where other non-employment (Other Non-Employed group, 7.8%) or full work disability (Full Work Disability group, 7.7%) became the prevailing status. Lower educational level and income predicted assignment to all other groups than the Sustained Work group. Additional predictors were identified, yet these differed between the trajectory groups. CONCLUSIONS: The majority of the pSA users maintained a connection to working life, yet weaker working life paths were also identified. The paths were determined by various individual and work-related factors that can help health professionals and employers to better target support measures particularly towards individuals whose connection to working life is at risk to weaken after the use of pSA.

A carboxyl-functionalized covalent organic polymer for the efficient adsorption of saxitoxin.

Saxitoxin (STX), the most widely distributed neurotoxin in marine waters and emerging cyanotoxin of concern in freshwaters, causes paralytic shellfish poisoning in humans upon consumption of contaminated shellfish. To allow for the efficient monitoring of this biotoxin, it is of high importance to find high-affinity materials for its adsorption. Herein, we report the design and synthesis of a covalent organic polymer for the efficient adsorption of STX. Two ß-keto-enamine-based materials were prepared by self-assembly of 2,4,6-triformylphloroglucinol (Tp) with 2,5-diaminobenzoic acid (Pa-COOH) to give TpPa-COOH and with 2,5-diaminotoluene (Pa-CH3) to give TpPa-CH3. The carboxylic acid functionalized TpPa-COOH outperformed the methyl-bearing counterpart TpPa-CH3 by an order of magnitude despite the higher long-range order and surface area of the latter. The adsorption of STX by TpPa-COOH was fast with equilibrium reached within 1 h, and the Langmuir adsorption model gave a calculated maximum adsorption capacity, Qm, of 5.69 mg g-1, making this material the best reported adsorbent for this toxin. More importantly, the prepared TpPa-COOH also showed good reusability and high recovery rates for STX in natural freshwater, thereby highlighting the material as a good candidate for the extraction and pre-concentration of STX from aquatic environments.

Evaluation of Covalent Organic Frameworks for the low-cost, rapid detection of Shiga Toxin-producing Escherichia coli in ready-to-eat salads.

BACKGROUND: Ready-to-eat products, such as leafy greens, must be carefully controlled as they are directly consumed without any treatment to reduce the presence of potential pathogens. Food industries, especially those that process products with short shelf-life, demand rapid detection of foodborne pathogens such as Shiga Toxin-producing Escherichia coli (STEC). In this sense, molecular methods can fulfill both requirements of turnaround time and consumer safety. The most popular rapid methods are those based on real-time PCR (qPCR) however, vegetables contain inhibitory compounds that may inhibit the amplification reaction thus, there is a need for novel sample preparation protocols. RESULTS: In the current study, a low-cost sample treatment based on sequential filtration steps was developed. This protocol was combined with covalent organic frameworks (COFs), and compared against a chelating resin, to evaluate their performance by multiplex qPCR targeting the major virulence genes of STEC, namely stx1, stx2, and eae, along with the rfbE for the specific identification of serogroup O157 due to its particularly high incidence, and an Internal Amplification Control to assess reaction inhibition. The optimized sample treatment effectively removed vegetable qPCR inhibitory compounds, and it was possible to detect STEC in spiked ready-to-eat salad samples in one working day, roughly 5 h, with an LOD50 of 8.7 CFU/25 g with high diagnostic sensitivity and specificity. The method was also assessed in samples with cold-stressed bacteria with good results, further demonstrating its applicability. SIGNIFICANCE: It was demonstrated for the first time that COFs are suitable for DNA extraction and purification. In addition to this, due to the tunable nature of these materials, it is envisioned that future modifications in terms of pore size or combination with magnetic materials, will allow to further improve their performance. In addition to this, the rapid and low-cost sample treatment protocol developed demonstrated suitable for the rapid screening of STEC vegetable samples.

Towards All-Non-Vacuum-Processed Photovoltaic Systems: A Water-Based Screen-Printed Cu(In,Ga)Se2 Photoabsorber with a 6.6% Efficiency.

During the last few decades, major advances have been made in photovoltaic systems based on Cu(In,Ga)Se2 chalcopyrite. However, the most efficient photovoltaic cells are processed under high-energy-demanding vacuum conditions. To lower the costs and facilitate high-throughput production, printing/coating processes are proving to be effective solutions. This work combined printing, coating, and chemical bath deposition processes of photoabsorber, buffer, and transparent conductive layers for the development of solution-processed photovoltaic systems. Using a sustainable approach, all inks were formulated using water and ethanol as solvents. Screen printing of the photoabsorber on fluorine-doped tin-oxide-coated glass followed by selenization, chemical bath deposition of the cadmium sulfide buffer, and final sputtering of the intrinsic zinc oxide and aluminum-doped zinc oxide top conductive layers delivered a 6.6% maximum efficiency solar cell, a record for screen-printed Cu(In,Ga)Se2 solar cells. On the other hand, the all-non-vacuum-processed device with spray-coated intrinsic zinc-oxide- and tin-doped indium oxide top conductive layers delivered a 2.2% efficiency. The given approaches represent relevant steps towards the fabrication of sustainable and efficient Cu(In,Ga)Se2 solar cells.

Piglets are a source of pathogenic Yersinia enterocolitica on fattening-pig farms.

To study the origin and spread of Yersinia enterocolitica among pigs, fecal and blood samples were repeatedly taken on a fattening farm. A few piglets were found to be already infected on breeding farms. After the piglets were mixed, the infection spread through the whole unit. Eventually, all the pigs excreted the pathogen.

Molecular recognition at the active site of factor Xa: cation-π interactions, stacking on planar peptide surfaces, and replacement of structural water.

Factor Xa, a serine protease from the blood coagulation cascade, is an ideal enzyme for molecular recognition studies, as its active site is highly shape-persistent and features distinct, concave sub-pockets. We developed a family of non-peptidic, small-molecule inhibitors with a central tricyclic core orienting a neutral heterocyclic substituent into the S1 pocket and a quaternary ammonium ion into the aromatic box in the S4 pocket. The substituents were systematically varied to investigate cation-π interactions in the S4 pocket, optimal heterocyclic stacking on the flat peptide walls lining the S1 pocket, and potential water replacements in both the S1 and the S4 pockets. Structure-activity relationships were established to reveal and quantify contributions to the binding free enthalpy, resulting from single-atom replacements or positional changes in the ligands. A series of high-affinity ligands with inhibitory constants down to K(i)=2 nM were obtained and their proposed binding geometries confirmed by X-ray co-crystal structures of protein-ligand complexes.