Effect of Graphene Addition on Polycaprolactone Scaffolds Fabricated Using Melt-Electrowriting

Melt-electrowriting (MEW) is an emerging method that combines electrospinning and extrusion printing, allowing the fabrication of micron-scale structures suitable for tissue engineering. Compared to other additive fabrication methods, melt-electro written structures can offer more appropriate substrates for cell culture due to filament size and mechanical characteristics of the fabricated scaffolds. In this study, polycaprolactone (PCL)/graphene composites were investigated for fabrication of micron-size scaffolds through MEW. It was demonstrated that the addition of graphene can considerably improve the processability of PCL to fabricate micron-scale scaffolds with enhanced resolution. The tensile strength of the scaffold prepared from PCL/graphene composite (with only 0.5 wt.% graphene) was proved significantly (by more than 270%), better than that of the pristine PCL scaffold. Furthermore, graphene was demonstrated to be a suitable material for tailoring the degradation process to avoid undesirable bulk degradation, rapid mass loss and damage to the internal matrix of the polymer. The findings of this study offer a promising route for the fabrication of high-resolution scaffolds with micron-scale resolution for tissue engineering.

The Rate, Amplitude, and Duration of Outbursts from Class 0 Protostars in Orion

At least half of a protostar’s mass is accreted in the Class 0 phase, when the central protostar is deeply embedded in a dense, infalling envelope. We present the first systematic search for outbursts from Class 0 protostars in the Orion clouds. Using photometry from Spitzer/IRAC spanning 2004 to 2017, we detect three outbursts from Class 0 protostars with ≥2 mag changes at 3.6 or 4.5 μm. This is comparable to the magnitude change of a known protostellar FU Ori outburst. Two are newly detected bursts from the protostars HOPS 12 and 124. The number of detections implies that Class 0 protostars burst every 438 yr, with a 95% confidence interval of 161 to 1884 yr. Combining Spitzer and WISE/NEOWISE data spanning 2004–2019, we show that the bursts persist for more than nine years with significant variability during each burst. Finally, we use 19–100 μm photometry from SOFIA, Spitzer, and Herschel to measure the amplitudes of the bursts. Based on the burst interval, a duration of 15 yr, and the range of observed amplitudes, 3%–100% of the mass accretion during the Class 0 phase occurs during bursts. In total, we show that bursts from Class 0 protostars are as frequent, or even more frequent, than those from more evolved protostars. This is consistent with bursts being driven by instabilities in disks triggered by rapid mass infall. Furthermore, we find that bursts may be a significant, if not dominant, mode of mass accretion during the Class 0 phase.

Accelerated mass loss of Himalayan glaciers since the Little Ice Age

Himalayan glaciers are undergoing rapid mass loss but rates of contemporary change lack long-term (centennial-scale) context. Here, we reconstruct the extent and surfaces of 14,798 Himalayan glaciers during the Little Ice Age (LIA), 400 to 700 years ago. We show that they have lost at least 40 % of their LIA area and between 390 and 586 km3 of ice; 0.92 to 1.38 mm Sea Level Equivalent. The long-term rate of ice mass loss since the LIA has been between − 0.011 and − 0.020 m w.e./year, which is an order of magnitude lower than contemporary rates reported in the literature. Rates of mass loss depend on monsoon influence and orographic effects, with the fastest losses measured in East Nepal and in Bhutan north of the main divide. Locally, rates of loss were enhanced with the presence of surface debris cover (by 2 times vs clean-ice) and/or a proglacial lake (by 2.5 times vs land-terminating). The ten-fold acceleration in ice loss we have observed across the Himalaya far exceeds any centennial-scale rates of change that have been recorded elsewhere in the world.

Can high SARS-CoV-2 adult vaccination rates help protect unvaccinated children? Evidence from a unique rapid mass vaccination campaign

Background: Mass vaccination has the potential to bring the COVID-19 pandemic to a halt by not only protecting individuals who have been vaccinated but also by providing cross-protection to unvaccinated individuals, such as children. However, this indirect protection effect from a vaccinated population onto an unvaccinated group is extremely difficult to observe in real-world situations. Methods: We studied cross-protection to unvaccinated individuals following an unprecedented rapid mass vaccination campaign in Europe. After a large outbreak of B.1.351 (Beta) in the district of Schwaz in Austria, the government offered every adult (16+) citizen of the district a vaccination with BNT162b2 between the 11th and 16th of March 2021. After this week, around 70% of the adult population of Schwaz had received their first dose, which made Schwaz the first widely inoculated region in Europe. The cohort of children under the age of 16 remained entirely unvaccinated (EMA only approved the vaccine for 12-15 year-olds on the 28th of May). This local mass vaccination campaign created a situation in which the vaccination coverage of the adult population sharply differed at the district border of Schwaz, while the coverage of those below the age of 16 remained the exact same. We compared SARS-CoV-2 cases among the adult population as well as children in Schwaz with case numbers of the same age cohorts from control regions. First, we compared Schwaz with a control group of other Austrian districts highly similar to Schwaz in many socio-demographic characteristics as well as in infection spread prior to the mass vaccination campaign. Second, we compared local populations residing along the border of Schwaz which live in the very same geographic area but with different vaccination coverage because they were not included in the vaccination campaign. Interpretation: Prior the mass vaccination campaign, we observed very similar infection spread across all age cohorts in Schwaz and the control regions. Around 3-4 weeks after the campaign, infections started to diverge between Schwaz and the control regions. While the difference was largest among the population aged 16–50 years (which was offered vaccination in the campaign), we also observed a statistically significant reduction in cases among the group of unvaccinated children. Our findings are robust to changes in the control group, as well as controls of a rich set of time and region specific effects. Policy implications: Our results constitute one of the first evidence of an indirect cross-protection effect from a group of vaccinated individuals to an unvaccinated group (in our case children). Given that in many countries the proposition to keep schools open during the academic year 2021/22 is a top priority, this evidence of community-protection is highly policy relevant.

Estimation of Populuseuphratica Forest Leaf Litterfall and Time Variation of Nutrient in Leaf Litter during Decomposition along the Main Channel of the Tarim River, China

Accurate determination of annual leaf litter amount constitutes the basis of scientific leaf litter nutrient release assessment. In this study, we tried to establish an equation between leaf litter amount and relevant tree characteristics of Populus euphratica (P. euphratica) tree on an individual scale, and to find the leaf litter nutrient content variation within 760 d incubation experiment in the main channel of the Tarim River, China. Results showed that there was no proper equation between leaf litter amount and tree height or diameter at breast height. There was great difference in leaf litter amount on an individual scale. The mean annual leaf litter amount per tree was 10.2, 14.83 kg/y obtained by field survey and the equation between annual leaf litter amount and canopy area on an individual scale, respectively. Leaf litter mass changed over incubation time and exhibited three main phases: an initial slow decomposition phase (0–173 d) with mass loss; a rapid mass loss phase (173–290 d); and a second rapid mass loss phase (470–560 d). Overall, carbon (C) and potassium (K) content decreased, and nitrogen (N) and phosphorus (P) content increased in a fluctuating manner over time in the P. euphratica leaf litter.

Hillslope Form and Process: History 1960− 2000+

The study of hillslopes has been dominated by the expansion of studies into process rates and mechanisms. Perhaps the greatest volume of work has been on the ‘wash’ processes of soil erosion, but there has also been significant work on the diffusive mass movements of linear and non-linear ‘creep’ that shape the convexity of hilltops, on more rapid mass movements and on solution processes. There has also been fresh work on distinctive processes in coastal, arid and cold-climate environments.Accompanying and integrated with process understanding, and made possible by ubiquitous computational power, modelling has developed from soluble mathematical simplifications to complex simulations that incorporate much of our understanding of process and climate.Particular topics that have seen significant advance include a more complete understanding of drainage density and texture, and a broadening of interest to encompass the ‘critical zone’ that constructively unifies the land surface with the lower atmosphere, the biosphere and the regolith. There has also been a change of focus towards steeplands, dominated by mass movements, supply limited removal and tectonic activity.Most recently, and now incorporated into the concept of the ‘Anthropocene’, human impact is now receiving increasing attention as we acknowledge its accelerating role in changing landscapes and their relationships.

The effects of rapid mass vaccination against SARS-CoV-2 and its Variants-of-Concern: Evidence from an early VoCs hotspot

We studied the real-life effect of an unprecedented rapid mass vaccination campaign. Following a large outbreak of B.1.351 and B.1.1.7/E484K in the district of Schwaz/Austria, 100,000 BNT162b2 doses were procured to mass vaccinate the entire adult population (16+) of the district between the 11th and 16th of March 2021. This made the district the first widely inoculated region in Europe. We examined the effect of this unique campaign on the number of infections including VoCs, hospital and intensive care unit (ICU) admissions. We compared Schwaz with (i) a control group of highly similar districts, and (ii) with populations residing in municipalities along the border of Schwaz which were just excluded from the campaign. We find large and significant decreases for all outcomes after the campaign, including VoCs cases. The reduction relative to the control regions was largest for younger age cohorts, which were mostly non-vaccinated in the rest of the country due to the age-gradient in the national vaccination plan. Our results demonstrate that rapid population-wide mass vaccination can be an effective tool to curb overall infections as well as VoCs.