The evolution of plastic deformation in a cellular Al alloy upon axial compression is monitored through a digital image correlation procedure. Three stages in the deformation response have been ...identified. The first involves localized plastic straining at cell nodes. It occurs uniformly and leads to a nominal loading modulus appreciably lower than the stiffness. The second comprises discrete bands of concentrated strain containing cell membranes that experience plastic buckling, elastically constrained by surrounding cells. In this phase, as the loading increases, previously formed bands harden, giving rise to new bands in neighboring regions. The localized bands exhibit a long-range correlation with neighboring bands separated by 3–4 cells along the loading direction. This length scale characterizes the continuum limit. Thirdly, coincident with a stress peak,
σ
o, one of the bands exhibits complete plastic collapse. As the strain increases, this process repeats, subject to small stress oscillations around
σ
o.
Neurodegeneration affects millions of Americans each year, occurring in later periods of life, where its onset is induced by neuroinflammation and oxidative stress. Flavonoids are known to protect ...against damages caused by reactive oxygen species (ROS) and reactive nitrogen species (RNS). This study evaluated the effect of hesperetin (HST), a major flavonoid found in oranges and mandarins, on LPS‐activated BV‐2 microglial cells. The obtained results of RT‐PCR showed that HST down‐regulated the mRNA expression of PD‐L1 in more than 50% of the LPS‐activated cells. In addition, HST induced the mRNA expression of Nrf2, which is involved in the transcription of several antioxidant genes. Moreover, the data from the oxidative stress PCR arrays showed that after 24 h, the concentration of 100 µM of HPT modulated numerous genes that regulate oxidative stress and inflammatory processes. HST down‐regulated the mRNA expression of ERCC6, ACTB, SQSTM11, NOS2, and NCF1 and up‐regulated the expression of HMOX1, which participate not only in excessive oxidative stress processes, by also in exacerbated inflammatory states. Both CAT and SOD enzymatic assays showed that treatment with HSP and LPS alone had no effect on CAT expression, but when cells were treated with the combination of HST and LPS, there was a reduction in these expressions enzymes. The quantitative glutathione assays demonstrated that only the combination treatment of HST and LPS reduced the expression of glutathione after a 24‐h treatment period. In conclusion, these data show that hesperetin modulates several genes associated with oxidative stress and neuroinflammation and may potentially slow the progression of neurodegeneration.
ABSTRACT
We consider a scenario in which Sgr A* is in a massive black hole binary (MBHB) with an as-of-yet undetected supermassive or intermediate-mass black hole companion. Dynamical encounters ...between this MBHB and single stars in its immediate vicinity would eject hypervelocity stars (HVSs) with velocities beyond the Galactic escape velocity of the Galaxy. In this work, we use existing HVS observations to constrain for the first time the existence of a companion to Sgr A*. We simulate the ejection of HVSs via the ‘MBHB slingshot’ scenario and show that the population of HVSs detectable today depends strongly on the companion mass and the separation of the MBHB. We demonstrate that the lack of uncontroversial HVS candidates in Gaia Data Release 3 places a firm upper limit on the mass of a possible Sgr A* companion. Within one milliparsec of Sgr A*, our results exclude a companion more massive than $2000 \, \mathrm{M_\odot }$. If Sgr A* recently merged with a companion black hole, our findings indicate that unless this companion was less massive than $500 \, \mathrm{M_\odot }$, this merger must have occurred at least 10 Myr ago. These results complement and improve upon existing independent constraints on a companion to Sgr A* and show that large regions of its parameter space can now be ruled out.
Microplastics (MPs) and nanoplastics (NPs) from mulch films and other plastic materials employed in vegetable and small fruit production pose a major threat to agricultural ecosystems. For conducting ...controlled studies on MPs' and NPs' (MNPs') ecotoxicity to soil organisms and plants and fate and transport in soil, surrogate MNPs are required that mimic MNPs that form in agricultural fields. We have developed a procedure to prepare MPs from plastic films or pellets using mechanical milling and sieving, and conversion of the resultant MPs into NPs through wet grinding, both steps of which mimic the degradation and fragmentation of plastics in nature. The major goal of this study was to determine if cryogenic exposure of two biodegradable mulch films effectively mimics the embrittlement caused by environmental weathering in terms of the dimensional, thermal, chemical, and biodegradability properties of the formed MNPs. We found differences in size, surface charge, thermal and chemical properties, and biodegradability in soil between MNPs prepared from cryogenically treated vs. environmentally weathered films, related to the photochemical reactions occurring in the environment that were not mimicked by cryogenic treatment, such as depolymerization and cross-link formation. We also investigated the size reduction process for NPs and found that the size distribution was bimodal, with populations centered at 50 nm and 150–300 nm, and as the size reduction process progressed, the former subpopulation's proportion increased. The biodegradability of MPs in soil was greater than for NPs, a counter-intuitive trend since greater surface area exposure for NPs would increase biodegradability. The result isassociated with differences in surface and chemical properties and to minor components that are readily leached out during the formation of NPs. In summary, the use of weathered plastics as feedstock would likely produce MNPs that are more realistic than cryogenically-treated unweathered films for use in experimental studies.
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•Micro- (MPs) and nanoplastics (NPs) were prepared for environmental lab studies.•Environmentally weathered and cryogenically treated biodegradable mulches were used.•MNPs' Physicochemical properties differed between cryogenic and weathered films.•With increased severity, NPs' size distribution became monodisperse: <100 nm.•MPs biodegraded more rapidly than NPs due to differences in chemical properties.
Aims/hypothesis
Recent studies have shown that mesenchymal stem cells (MSCs) secrete several factors that improve survival and function of transplanted islets. Implantation of islets beneath the ...kidney capsule results in morphological changes, due to interactions of the graft with the host, thus impairing islet function. We co-transplanted MSCs with islets to determine their effects on the remodelling process and studied graft function in a mouse model of minimal islet mass.
Methods
Islets were syngeneically transplanted, either alone or with kidney-derived MSCs, underneath the kidney capsule of streptozotocin-induced diabetic C57Bl/6 mice. Blood glucose levels were monitored and intraperitoneal glucose tolerance tests carried out. Hormone contents of grafts and pancreas were assessed by radioimmunoassay. Graft morphology and vascularisation were evaluated by immunohistochemistry.
Results
MSCs improved the capacity of islet grafts to reverse hyperglycaemia, with 92% of mice co-transplanted with MSCs reverting to normoglycaemia, compared with 42% of those transplanted with islets alone. Average blood glucose concentrations were lower throughout the 1 month monitoring period in MSC co-transplanted mice. MSCs did not alter graft hormone content. Islets co-transplanted with MSCs maintained a morphology that more closely resembled that of islets in the endogenous pancreas, both in terms of size, and of endocrine and endothelial cell distribution. Vascular engraftment was superior in MSC co-transplanted mice, as shown by increased endothelial cell numbers within the endocrine tissue.
Conclusions/interpretation
Co-transplantation of islets with MSCs had a profound impact on the remodelling process, maintaining islet organisation and improving islet revascularisation. MSCs also improved the capacity of islets to reverse hyperglycaemia.
We report results from a study of nitric oxide nightglow over the northern hemisphere of Mars during winter, the southern hemisphere during fall equinox, and equatorial latitudes during summer in the ...northern hemisphere based on observations of the δ and γ bands between 190 and 270 nm by the Imaging UltraViolet Spectrograph (IUVS) on the Mars Atmosphere and Volatile EvolutioN mission (MAVEN) spacecraft. The emission reveals recombination of N and O atoms dissociated on the dayside of Mars and transported to the nightside. We characterize the brightness (from 0.2 to 30 kR) and altitude (from 40 to 115 km) of the NO nightglow layer, as well as its topside scale height (mean of 11 km). We show the possible impact of atmospheric waves forcing longitudinal variability, associated with an increased brightness by a factor of 3 in the 140–200° longitude region in the northern hemisphere winter and in the −102° to −48° longitude region at summer. Such impact to the NO nightglow at Mars was not seen before. Quantitative comparison with calculations of the LMD‐MGCM (Laboratoire de Météorologie Dynamique‐Mars Global Climate Model) suggests that the model globally reproduces the trends of the NO nightglow emission and its seasonal variation and also indicates large discrepancies (up to a factor 50 fainter in the model) in northern winter at low to middle latitudes. This suggests that the predicted transport is too efficient toward the night winter pole in the thermosphere by ∼20° latitude north.
Key Points
We study nitric oxide nightglow at equinox, summer, and winter and compare to the LMD‐MGCM predictions
This study reveals the seasonal control on the emission, as well as unexpected longitudinal variations caused by waves/tides
We suggest future work on NO nightglow using GCMs and IUVS disk images and tangent limb data
To assess the effectiveness of annual ovarian cancer screening (transvaginal ultrasound and serum CA125 estimation) in reducing mortality from ovarian cancer in women at increased genetic risk.
A ...cohort of 3532 women at increased risk of ovarian cancer was screened at five European centres between January 1991 and March 2007. Survival from diagnosis of ovarian cancer was calculated using Kaplan-Meier analysis and compared for proven BRCA1/2 carriers with non-carriers and whether the cancer was detected at prevalence or post-prevalent scan. Screening was performed by annual transvaginal ultrasound and serum CA125 measurement.
64 epithelial ovarian malignancies (59 invasive and 5 borderline), developed in the cohort. 26 tumours were detected at prevalent round; there were 27 incident detected cancers and 11 interval. 65% of cancers were stage 3 or 4, however, stage and survival were little different for prevalent versus post-prevalent cancers. Five year and 10 year survival in 49 BRCA1/2 mutation carriers was 58.6% (95% CI 50.9% to 66.3%) and 36% (95% CI 27% to 45%), which was significantly worse than for 15 non-BRCA carriers (91.8%, 95% CI 84% to 99.6%, both 5 and 10 year survival p = 0.015). However, when borderline tumours were excluded, the difference in survival between carriers and non-carriers was no longer significant.
Annual surveillance, by transvaginal ultrasound scanning and serum CA125 measurement, in women at increased familial risk of ovarian cancer is ineffective in detecting tumours at a sufficiently early stage to influence substantially survival in BRCA1/2 carriers.
Mercury in seafood is a neurotoxicant that threatens human health. Dynamic rates of mercury emission, re-emission, and atmospheric deposition warrant studies into mercury concentrations in fish ...because many are consumed by humans and can serve as sentinels of mercury levels in the environment. We modeled trends in total mercury content in an apex marine fish predator, Atlantic blue marlin Makaira nigricans, whose muscle tissues were opportunistically sampled from North Carolina (USA) sportfishing tournaments over a discontinuous time period: between 1975 and 77 and 1998–2021 (n = 148). The model-estimated influence of marlin weight on total mercury concentration was constant across years (shared slope) allowing for comparisons of weight-corrected mercury concentrations among years. Weight-corrected total mercury concentrations revealed an inter-decadal decline of approximately 45 % between the 1970s and late 1990s and then variable but relatively stable concentrations through 2021. The mean (SD) wet weight concentration of total mercury was 9.47 (4.11) from 1975 to 77 and 4.17 (2.61) from 2020 to 2021. Methylmercury and selenium were measured on a subset of fish to address questions related to human health and consumption. Methylmercury levels (mean = 0.72 μg/g) were much lower than total mercury (mean = 4.69 μg/g) indicating that total mercury is not a good proxy for methylmercury in Atlantic blue marlin. Selenium, examined as a Se:Hg molar ratio and as a selenium health benefit value (HBVSe), showed high protective value against mercury toxicity. Long-term trends in the concentration of mercury in blue marlin should continue to be monitored to determine whether policies to mitigate anthropogenic contributions to global mercury are achieving their intended goals and to provide information to inform safe human consumption.
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•Long-term studies of offshore marine apex predators are valuable for indexing ambient heavy metal concentrations.•Atlantic blue marlin muscle collected from 1975 to 2021 was analyzed for total mercury, methylmercury, and selenium.•Total mercury concentrations declined from the 1970s to late 1990s, but remained approximately constant during this century.•Methylmercury is a small percentage of total mercury in Atlantic blue marlin, which is not typically observed in fish.•High selenium concentrations in Atlantic blue marlin tissue may substantially offset mercury toxicity in human consumers.
Parental criminal justice system (CJS) involvement is a marker for child protective services (CPS) involvement.
To document how parental criminal case processing affects children’s CPS involvement.
...Participants included mothers and fathers with a serious criminal charge (mothers = 78,882; fathers = 165,070) and without any criminal charge (mothers = 962,963; fathers = 743,604) between 2008-2012. Statewide North Carolina records on court proceedings, births, CPS assessments/investigations, and foster care placements were used.
The observational unit was an individual’s first charge date of a year. Outcomes were CPS assessment/investigation and foster care entry within six months and alternatively three years following the charge. Key explanatory variables were whether the charges resulted in prosecution, conviction following prosecution, and an active sentence conditional on conviction. An instrumental variables approach was used.
Parents charged with a criminal offense had higher rates of having a CPS assessment/investigation during the three years preceding the charge than parents who were not charged. Among mothers who were convicted, CPS assessment/investigation increased 8.1 percent (95 % CI: 2.2, 13.9) and 9.5 percent (95 % CI: 1.3, 17.6) 6 months and 3 years following the charge. An active sentence increased CPS assessment/investigations by 21.6 percent (95 % CI: 6.4, 36.7) within 6 months. For fathers, active sentence increased foster care placement by 1.6 percent (95 % CI: 0.24, 2.9) within 6 months of the criminal charge.
Changing parental incarceration rates would change CPS caseloads substantially. The criminal justice and CPS systems work with overlapping populations, data and services sharing should be considered a high priority.
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