Molecular dynamics simulations were used to study deformation mechanisms during uniaxial tensile deformation of an amorphous polyethylene polymer. The stress-strain behavior comprised elastic, yield, ...strain softening and strain hardening regions that were qualitatively in agreement with previous simulations and experimental results. The chain lengths, number of chains, strain rate and temperature dependence of the stress-strain behavior was investigated. The energy contributions from the united atom potential were calculated as a function of strain to help elucidate the inherent deformation mechanisms within the elastic, yield, and strain hardening regions. The results of examining the partitioning of energy show that the elastic and yield regions were mainly dominated by interchain non-bonded interactions whereas strain hardening regions were mainly dominated by intra-chain dihedral motion of polyethylene. Additional results show how internal mechanisms associated with bond length, bond angle, dihedral distributions, change of free volume and chain entanglements evolve with increasing deformation.
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Oxygen minimum zones (OMZs) are marine regions where O
is undetectable at intermediate depths. Within OMZs, the oxygen-depleted zone (ODZ) induces anaerobic microbial processes that lead to fixed ...nitrogen loss via denitrification and anammox. Surprisingly, nitrite oxidation is also detected in ODZs, although all known marine nitrite oxidizers (mainly Nitrospina) are aerobes. We used metagenomic binning to construct metagenome-assembled genomes (MAGs) of nitrite oxidizers from OMZs. These MAGs represent two novel Nitrospina-like species, both of which differed from all known Nitrospina species, including cultured species and published MAGs. Relative abundances of different Nitrospina genotypes in OMZ and non-OMZ seawaters were estimated by mapping metagenomic reads to newly constructed MAGs and published high-quality genomes of members from the Nitrospinae phylum. The two novel species were present in all major OMZs and were more abundant inside ODZs, which is consistent with the detection of higher nitrite oxidation rates in ODZs than in oxic seawaters and suggests novel adaptations to anoxic environments. The detection of a large number of unclassified nitrite oxidoreductase genes in the dataset implies that the phylogenetic diversity of nitrite oxidizers is greater than previously thought.
Summary
Background
Topical photodynamic therapy (PDT) is widely used to treat superficial nonmelanoma skin cancer and dysplasia, and is generally well tolerated. However, as with all treatments, ...adverse effects may occur and awareness may facilitate approaches to prevention and management.
Objectives
To review the available evidence relating to the adverse effects of topical PDT, to help inform recommendations in updated clinical guidelines produced by the British Association of Dermatologists and British Photodermatology Group, and the efficacy of preventative and therapeutic approaches.
Methods
This review summarizes the published evidence related to the adverse effects of topical PDT and attempts to interpret this evidence in the context of patient risk and management.
Results
Pain and discomfort during PDT are acute adverse effects, which can be minimized through the use of modified and low‐irradiance PDT regimens and do not therefore usually limit successful treatment delivery. Other adverse effects include the risk of contact allergy to photosensitizer prodrugs, although this is rare but should be kept in mind, particularly for patients who have received multiple PDT treatments to larger areas. There are no other significant documented longer‐term risks and, to date, no evidence of cumulative toxicity or photocarcinogenic risk.
Conclusions
Topical PDT is usually well tolerated, reinforcing the utility of this important therapeutic option in dermatology practice. The main acute adverse effect of pain can typically be minimized through preventative approaches of modified PDT regimens. Other adverse effects are uncommon and generally do not limit treatment delivery.
What's already known about this topic?
Photodynamic therapy (PDT) is widely used in dermatology.
Pain is the most well documented adverse effect.
Methods of effective pain relief are limited.
What does this study add?
This review scrutinizes the literature relating to adverse effects of PDT and management approaches.
PDT‐induced pain can usually be effectively prevented and managed through adjustments to PDT regimens, such as using lower irradiance light delivery.
Phototoxic reactions are to be expected.
Other adverse effects are typically uncommon and not limiting.
Linked Editorial: Wulf. Br J Dermatol 2019; 180:695–696.
Plain language summary available online
We report a previously undescribed bacterial behavior termed electrokinesis. This behavior was initially observed as a dramatic increase in cell swimming speed during reduction of solid MnO₂ ...particles by the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1. The same behavioral response was observed when cells were exposed to small positive applied potentials at the working electrode of a microelectrochemical cell and could be tuned by adjusting the potential on the working electrode. Electrokinesis was found to be different from both chemotaxis and galvanotaxis but was absent in mutants defective in electron transport to solid metal oxides. Using in situ video microscopy and cell tracking algorithms, we have quantified the response for different strains of Shewanella and shown that the response correlates with current-generating capacity in microbial fuel cells. The electrokinetic response was only exhibited by a subpopulation of cells closest to the MnO₂ particles or electrodes. In contrast, the addition of 1 mM 9,10-anthraquinone-2,6-disulfonic acid, a soluble electron shuttle, led to increases in motility in the entire population. Electrokinesis is defined as a behavioral response that requires functional extracellular electron transport and that is observed as an increase in cell swimming speeds and lengthened paths of motion that occur in the proximity of a redox active mineral surface or the working electrode of an electrochemical cell.
Power transformers are considered important and expensive items in electrical power networks. In this regard, the early discovery of potential faults in transformers considering datasets collected ...from diverse sensors can guarantee the continuous operation of electrical systems. Indeed, the discontinuity of these transformers is expensive and can lead to excessive economic losses for the power utilities. Dissolved gas analysis (DGA), as well as partial discharge (PD) tests considering different intelligent sensors for the measurement process, are used as diagnostic techniques for detecting the oil insulation level. This paper includes two parts; the first part is about the integration among the diagnosis results of recognized dissolved gas analysis techniques, in this part, the proposed techniques are classified into four techniques. The integration between the different DGA techniques not only improves the oil fault condition monitoring but also overcomes the individual weakness, and this positive feature is proved by using 532 samples from the Egyptian Electricity Transmission Company (EETC). The second part overview the experimental setup for (66/11.86 kV-40 MVA) power transformer which exists in the Egyptian Electricity Transmission Company (EETC), the first section in this part analyzes the dissolved gases concentricity for many samples, and the second section illustrates the measurement of PD particularly in this case study. The results demonstrate that precise interpretation of oil transformers can be provided to system operators, thanks to the combination of the most appropriate techniques.
Abstract Background Several legacy and emerging per- and polyfluoroalkyl substances (PFAS) have been regulated around the world. There is growing concern over the proliferation of alternative PFAS, ...as well as PFAS precursors. Biomonitoring data for PFAS are critical for assessing exposure and human health risk. Methods We collected serum samples from 289 adult female participants in a 2018–2021 follow-up study of the Maternal-Infant Research on Environmental Chemicals (MIREC) Canadian pregnancy cohort. Samples were analyzed for 40 PFAS using ultra-performance liquid chromatography–tandem mass spectrometry. For those compounds with > 50% detection, as well as the sum of these compounds, we describe serum concentrations and patterns of exposure according to sociodemographic and obstetrical history characteristics. Results 17 out of 40 PFAS were detected in > 50% of samples with 7 of these detected in > 97% of samples. Median 95th percentile concentrations (µg/L) were highest for PFOS (1.62 4.56), PFOA (0.69 1.52), PFNA (0.38 0.81), and PFHxS (0.33 0.92). Geometric mean concentrations of PFOA and PFHxS were approximately 2-fold lower among those with more children (≥ 3 vs. 1), greater number of children breastfed (≥ 3 vs. ≤ 1), longer lifetime duration of breastfeeding (> 4 years vs. ≤ 9 months), and shorter time since last pregnancy (≤ 4 years vs. > 8 years). We observed similar patterns for PFOS, PFHpS, and the sum of 17 PFAS, though the differences between groups were smaller. Concentrations of PFOA were higher among “White” participants, while concentrations of N-MeFOSE, N-EtFOSE, 7:3 FTCA, and 4:2 FTS were slightly higher among participants reporting a race or ethnicity other than “White”. Concentrations of legacy, alternative, and precursor PFAS were generally similar across levels of age, education, household income, body mass index, and menopausal status. Conclusions We report the first Canadian biomonitoring data for several alternative and precursor PFAS. Our findings suggest that exposure to PFAS, including several emerging alternatives, may be widespread. Our results are consistent with previous studies showing that pregnancy and breastfeeding are excretion pathways for PFAS.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT
We present the first intensive continuum reverberation mapping study of the high accretion-rate Seyfert galaxy Mrk 110. The source was monitored almost daily for more than 200 d with the ...Swift X-ray and ultraviolet (UV)/optical telescopes, supported by ground-based observations from Las Cumbres Observatory, the Liverpool Telescope, and the Zowada Observatory, thus extending the wavelength coverage to 9100 Å. Mrk 110 was found to be significantly variable at all wavebands. Analysis of the intraband lags reveals two different behaviours, depending on the time-scale. On time-scales shorter than 10 d the lags, relative to the shortest UV waveband (∼1928 Å), increase with increasing wavelength up to a maximum of ∼2 d lag for the longest waveband (∼9100 Å), consistent with the expectation from disc reverberation. On longer time-scales, however, the g-band lags the Swift BAT hard X-rays by ∼10 d, with the z-band lagging the g-band by a similar amount, which cannot be explained in terms of simple reprocessing from the accretion disc. We interpret this result as an interplay between the emission from the accretion disc and diffuse continuum radiation from the broad-line region.
Summary
Background
Topical photodynamic therapy (PDT) is an established treatment option for low‐risk basal cell carcinoma (BCC).
Objectives
To compare efficacy, cosmesis and tolerability of PDT for ...BCC with alternative treatments.
Methods
MEDLINE, PubMed, Embase and CENTRAL databases were searched from inception until 1 September 2017. Included studies were randomized controlled trials (RCTs) of PDT for nodular (n) and superficial (s) BCC reporting at least one of the following outcomes: clearance at 3 months and sustained at 1 or 5 years; recurrence at ≥ 1 year; cosmesis; adverse events; tolerability.
Results
From 2331 search results, 15 RCTs (2327 patients; 3509 BCCs) were included. PDT efficacy (5‐year sustained clearance) was high but inferior to excisional surgery nBCC pooled risk ratio (RR) 0·76; 95% confidence interval (CI) 0·63–0·91, and without re‐treatment of partially responding lesions, was modestly inferior to imiquimod (sBCC: RR 0·81; 95% CI 0·70–0·95) and similar to fluorouracil (sBCC: RR 0·88; 95% CI 0·75–1·04). Five‐year sustained clearance was inferior with conventional vs. fractionated PDT (sBCC: RR 0·76; 95% CI 0·68–0·84). PDT cosmesis was superior to surgery (sBCC: RR 1·68, 95% CI 1·32–2·14; nBCC: RR 1·82, 95% CI 1·19–2·80) and cryosurgery (BCC: RR 3·73, 95% CI 1·96–7·07), and without re‐treatment of partially responding lesions was similar to imiquimod (sBCC: RR 1·01, 95% CI 0·85–1·19) and fluorouracil (sBCC: RR 1·04, 95% CI 0·88–1·24). Peak pain was higher but of shorter duration with PDT than topical treatments. Serious adverse reactions were rarer with PDT than imiquimod (sBCC: RR 0·05, 95% CI 0·00–0·84) and fluorouracil (sBCC: RR 0·11, 95% CI 0·01–2·04). Combination PDT regimens demonstrated reduced recurrence and improved cosmesis; however, results from these small studies were often nonsignificant.
Conclusions
PDT is an effective treatment for low‐risk BCC, with excellent cosmesis and safety. Imiquimod has higher efficacy than single‐cycle PDT but more adverse effects. Highest efficacy is with excisional surgery. Fractionated and combination PDT options warrant further study.
What's already known about this topic
Topical photodynamic therapy (PDT) is one of a range of established treatment options for low‐risk basal cell carcinoma (BCC).
BCC clearance is reported to be higher with imiquimod than with single‐cycle PDT.
What does this study add?
This is the largest systematic review and meta‐analysis to date of PDT for BCC and incorporates National Institute for Health and Care Excellence‐approved GRADE assessment of evidence quality, including 15 RCTs (2327 patients with 3509 BCCs).
Serious adverse reactions are less common with PDT than with imiquimod.
Peak pain is higher with PDT than topical therapies but is of shorter duration.
Fractionated PDT offers superior clearance to conventional PDT.
Combination PDT treatments show promise but require further study.
Linked Editorial: Lim. Br J Dermatol 2018; 179:1240–1241.
Plain language summary available online
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