Photoactive Fe Catalyst for Light-Triggered Alkyd Paint Curing

[Image: see text] Herein, we show that the photoactive complexes [(Cp)Fe(arene)](+) (Cp = cyclopentadienyl; arene = C(6)H(6), C(6)H(5)Me) act as latent catalysts that allow for photochemical control over the onset of alkyd paint curing, without the need for antiskinning agents such as the volatile 2-butanone oxime normally used to prevent curing during paint storage. The highly soluble neutral complexes [(Cp)Fe(Ch)] and [(Cp)Fe(Ch′)] (Ch = cyclohexadienyl, Ch′ = methylcyclohexadienyl) readily convert to the photoactive complexes [(Cp)Fe(arene)](+) upon oxidation in alkyd, allowing the latter to be dosed in a wide range of concentrations. Infrared and Raman studies show similar spectral changes of the alkyd paint matrix as have been observed in alkyd curing mediated by well-known, industrially applied cobalt- and manganese-based catalyst Co(neodecanoate)(2) and [(Me(3)TACN)(2)Mn(2)(μ-OOCR)(3)](OOCR). The [(Cp)Fe(Ch)]/[(Cp)Fe(arene)](+) system performs equally well as these cobalt- and manganese-based catalysts in terms of drying time and outperform the manganese catalyst by showing a hardness development (increase) similar to that of the cobalt-based catalyst. Based on electron paramagnetic resonance and light–activity studies, we propose that photolysis of [(Cp)Fe(arene)](+) generates short-lived active Fe(II) species, explaining the desired latency. The [(Cp)Fe(Ch)]/[(Cp)Fe(arene)](+) alkyd curing systems presented herein are unique examples of intrinsically latent paint curing catalysts that (1) are based on an abundant and harmless transition metal (Fe), (2) do not require any antiskinning agents, and (3) show favorable performance in terms of drying times and hardness development

Аналитическое описание порообразования при установившейся ползучести металлов

На основании обобщения синтезной теории пластичности и ползучести аналитически описан процесс порообразования в металле во время установившейся ползучести. Получены соотношения между объемом микропор и деформацией установившейся ползучести при разных уровнях напряжения. Аналитически полученные результаты хорошо согласуются с экспериментальными.На основі узагальнення синтезної теорії пластичності і повзучості представлено аналітичний опис процесу пороутворення за усталеної повзучості металів. Отримано співвідношення між об’ємом мікропор і деформацією усталеної повзучості за різних рівнів напруження. Аналітичні результати добре узгоджуються з експериментальними.Using generalization of the synthetic theory of plasticity and creep, we provide the analytical description of void formation in a metal under steady-state creep conditions. We obtained the relations between the size of microvoids and the steady-state creep strain for various stress levels. Analytical results are in a good agreement with the available experimental data

A semi-automated non-radiactive system for measuring recovery of RNA synthesis and unscheduled DNA synthesis using ethynyluracil derivatives

Nucleotide excision repair (NER) removes the major UV-photolesions from cellular DNA. In humans, compromised NER activity is the cause of several photosensitive diseases, one of which is the skin-cancer predisposition disorder, xeroderma pigmentosum (XP). Two assays commonly used in measurement of NER activity are ‘unscheduled DNA synthesis (UDS)’, and ‘recovery of RNA synthesis (RRS)’, the latter being a specific measure of the transcription-coupled repair sub-pathway of NER. Both assays are key techniques for research in NER as well as in diagnoses of NER-related disorders. Until very recently, reliable methods for these assays involved measurements of incorporation of radio-labeled nucleosides. We have established non-radioactive procedures for determining UDS and RRS levels by incorporation of recently developed alkyne-conjugated nucleoside analogues, 5-ethynyl-2′-deoxyuridine (EdU) and 5-ethynyuridine (EU). EdU and EU are respectively used as alternatives for 3H-thymidine in UDS and for 3H-uridine in RRS. Based on these alkyne-nucleosides and an integrated image analyser, we have developed a semi-automated assay system for NER-activity. We demonstrate the utility of this system for NER-activity assessments of lymphoblastoid samples as well as primary fibroblasts. Potential use of the system for large-scale siRNA-screening for novel NER defects as well as for routine XP diagnosis are also considered

MAGNETIC FORCES IN ORTHODONTICS

BACKGROUND: Pneumococcus is a major human pathogen and the polysaccharide capsule is considered its main virulence factor. Nevertheless, strains lacking a capsule, named non-typeable pneumococcus (NT), are maintained in nature and frequently colonise the human nasopharynx. Interest in these strains, not targeted by any of the currently available pneumococcal vaccines, has been rising as they seem to play an important role in the evolution of the species. Currently, there is a paucity of data regarding this group of pneumococci. Also, questions have been raised on whether they are true pneumococci. We aimed to obtain insights in the genetic content of NT and the mechanisms leading to non-typeability and to genetic diversity. RESULTS: A collection of 52 NT isolates representative of the lineages circulating in Portugal between 1997 and 2007, as determined by pulsed-field gel electrophoresis and multilocus sequence typing, was analysed. The capsular region was sequenced and comparative genomic hybridisation (CGH) using a microarray covering the genome of 10 pneumococcal strains was carried out. The presence of mobile elements was investigated as source of intraclonal variation. NT circulating in Portugal were found to have similar capsular regions, of cps type NCC2, i.e., having aliB-like ORF1 and aliB-like ORF2 genes. The core genome of NT was essentially similar to that of encapsulated strains. Also, competence genes and most virulence genes were present. The few virulence genes absent in all NT were the capsular genes, type-I and type-II pili, choline-binding protein A (cbpA/pspC), and pneumococcal surface protein A (pspA). Intraclonal variation could not be entirely explained by the presence of prophages and other mobile elements. CONCLUSIONS: NT circulating in Portugal are a homogeneous group belonging to cps type NCC2. Our observations support the theory that they are bona-fide pneumococcal isolates that do not express the capsule but are otherwise essentially similar to encapsulated pneumococci. Thus we propose that NT should be routinely identified and reported in surveillance studies

10-year follow-up of patients with rheumatoid arthritis and secondary Sjogren's syndrome or sicca symptoms in daily clinical practice

Objective. To evaluate the presence of sicca symptoms and secondary Sjogren's syndrome (SS) and the association with clinical characteristics, functional tests and patient-reported outcomes in patients with rheumatoid arthritis (RA) at baseline and after 10 years of follow-up. Methods. A cohort of RA patients was evaluated in 2008 and re-evaluated in 2018 with respect to sicca symptoms, presence of secondary SS according to AECG classification criteria, disease activity of RA and patient-reported outcomes. Patient characteristics were compared between the RA-non-sicca, RA-sicca and RA-SS groups. Results. Of the original 2008 cohort of 96 RA patients, 32 (33%) had sicca symptoms and 6 (6.3%) secondary SS. Of the 36 patients who agreed to be reevaluated in 2018, 6 (17%) had sicca symptoms and 2 (6%) developed secondary SS. In the majority of patients, sicca symptoms were reversible while the functional tests of salivary and lacrimal glands significantly decreased. 67% of RA-sicca patients had no sicca complaints at the second screening, while only two RA-sicca patients developed secondary SS. RA-SS patients and, to a slightly lesser extent, RA-sicca patients had significantly higher RA disease activity (DAS-28), lower lacrimal (Schirmer's test) and salivary gland function, more limitations in daily activities (HAQ), worse health-related quality of life (RAND-36), more fatigue (MFI) and more patient symptoms (ESSPRI) compared to RA-non-sicca patients. Conclusion. Secondary SS was found in a minor subset of the RA patients. Sicca symptoms of the eyes or mouth were more frequent, but their presence varied over time. Higher RA disease activity was associated with SS and sicca symptoms. These patients had lower gland function and worse patient-reported outcomes

10-year follow-up of patients with rheumatoid arthritis and secondary Sjogren's syndrome or sicca symptoms in daily clinical practice

Objective. To evaluate the presence of sicca symptoms and secondary Sjogren's syndrome (SS) and the association with clinical characteristics, functional tests and patient-reported outcomes in patients with rheumatoid arthritis (RA) at baseline and after 10 years of follow-up. Methods. A cohort of RA patients was evaluated in 2008 and re-evaluated in 2018 with respect to sicca symptoms, presence of secondary SS according to AECG classification criteria, disease activity of RA and patient-reported outcomes. Patient characteristics were compared between the RA-non-sicca, RA-sicca and RA-SS groups. Results. Of the original 2008 cohort of 96 RA patients, 32 (33%) had sicca symptoms and 6 (6.3%) secondary SS. Of the 36 patients who agreed to be reevaluated in 2018, 6 (17%) had sicca symptoms and 2 (6%) developed secondary SS. In the majority of patients, sicca symptoms were reversible while the functional tests of salivary and lacrimal glands significantly decreased. 67% of RA-sicca patients had no sicca complaints at the second screening, while only two RA-sicca patients developed secondary SS. RA-SS patients and, to a slightly lesser extent, RA-sicca patients had significantly higher RA disease activity (DAS-28), lower lacrimal (Schirmer's test) and salivary gland function, more limitations in daily activities (HAQ), worse health-related quality of life (RAND-36), more fatigue (MFI) and more patient symptoms (ESSPRI) compared to RA-non-sicca patients. Conclusion. Secondary SS was found in a minor subset of the RA patients. Sicca symptoms of the eyes or mouth were more frequent, but their presence varied over time. Higher RA disease activity was associated with SS and sicca symptoms. These patients had lower gland function and worse patient-reported outcomes

Failure to Engage Neural Plasticity through Practice of a High-difficulty Task is Accompanied by Reduced Motor Skill Retention in Older Adults

White the difficulty of a motor task can act as a stimulus for learning in younger adults, it is unknown how task difficulty interacts with age-related reductions in motor performance and altered brain activation. We examined the effects of task difficulty on motor performance and used electroencephalography (EEG) to probe task-related brain activation after acquisition and 24-h retention of a mirror star-tracing skill in healthy older adults (N = 36, 65-86 years). The results showed that the difficulty of the motor skill affected both the magnitude of motor skill learning and the underlying neural mechanisms. Behavioral data revealed that practicing a motor task at a high difficulty level hindered motor skill consolidation. The EEG data indicated that task difficulty modulated changes in brain activation after practice. Specifically, a decrease in task-related alpha power in frontal and parietal electrodes was only present after practice of the skill at the low and medium, but not the high difficulty level. Taken together, our findings show that a failure to engage neural plasticity through practice of a highdifficulty task is accompanied by reduced motor skill retention in older adults. The data help us better understand how older adults learn new motor skills and might have implications for prescribing motor skill practice according to its difficulty in rehabilitation settings. (c) 2020 The Author(s). Published by Elsevier Ltd on behalf of IBRO. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)