If Dark Matter is made of Weakly Interacting Massive Particles (WIMPs) with masses below
∼
20
GeV, the corresponding nuclear recoils in mainstream WIMP experiments are of energies too close, or ...below, the experimental threshold. Gas Time Projection Chambers (TPCs) can be operated with a variety of target elements, offer good tracking capabilities and, on account of the amplification in gas, very low thresholds are achievable. Recent advances in electronics and in novel radiopure TPC readouts, especially micro-mesh gas structure (Micromegas), are improving the scalability and low-background prospects of gaseous TPCs. Here we present TREX-DM, a prototype to test the concept of a Micromegas-based TPC to search for low-mass WIMPs. The detector is designed to host an active mass of
∼
0.300
kg of Ar at 10 bar, or alternatively
∼
0.160
kg of Ne at 10 bar, with an energy threshold below 0.4 keVee, and is fully built with radiopure materials. We will describe the detector in detail, the results from the commissioning phase on surface, as well as a preliminary background model. The anticipated sensitivity of this technique may go beyond current experimental limits for WIMPs of masses of 2–8 GeV.
Stripped-envelope supernovae (Types IIb, Ib, and Ic) that show little or no hydrogen comprise roughly one-third of the observed explosions of massive stars. Their origin and the evolution of their ...progenitors are not yet fully understood. Very massive single stars stripped by their own winds (≳25−30
M
⊙
at solar metallicity) are considered viable progenitors of these events. However, recent 1D core-collapse simulations show that some massive stars may collapse directly into black holes after a failed explosion, with a weak or no visible transient. In this Letter, we estimate the effect of direct collapse into a black hole on the rates of stripped-envelope supernovae that arise from single stars. For this, we compute single-star MESA models at solar metallicity and map their final state to their core-collapse outcome following prescriptions commonly used in population synthesis. According to our models, no single stars that have lost their entire hydrogen-rich envelope are able to explode, and only a fraction of progenitors left with a thin hydrogen envelope do (IIb progenitor candidates), unless we use a prescription that takes the effect of turbulence into account or invoke increased wind mass-loss rates. This result increases the existing tension between the single-star paradigm to explain most stripped-envelope supernovae and their observed rates and properties. At face value, our results point toward an even higher contribution of binary progenitors to stripped-envelope supernovae. Alternatively, they may suggest inconsistencies in the common practice of mapping different stellar models to core-collapse outcomes and/or higher overall mass loss in massive stars.
•We report the synthesis of magnetic nanofibrous materials.•Magnetic nanofibrous materials were obtained from the electrospinning technique.•We electrospun nanofibrous materials from CMC/PVA blends ...loaded with SMON.•Nanofibers' diameter decrease as the weight of SMON loaded in blends increases.•Magnetic nanofibrous materials display a novel soft ferromagnetic response.
In this paper, the synthesis of magnetic nanofibrous materials with a soft ferromagnetic response based on magnetite nanoparticles (SMON) loaded to aqueous carboxymethyl-cellulose (CMC)/polyvinyl-alcohol (PVA) polymeric blends is reported. The nanofibrous materials were obtained from the electrospinning of SMON-CMC/PVA blends with different SMON content, applying a constant tension of 15 kV. The synthesized samples were analyzed by transmission electron microscopy, scanning electron microscopy, attenuated total reflectance Fourier transform infrared, Raman and X-Ray photoelectron spectroscopy, as well as static magnetic measuring. Our experimental findings indicate that nanofibers’ diameter decreases as SMON content in the electrospun polymeric blends is increased, since these magnetic nanoparticles diminish the interactions between PVA and CMC molecules, which improves their spinnability. Moreover, the spatial distribution of SMON in the fibers provides to the synthesized nanofibrous materials a novel soft ferromagnetic response at room temperature. This phenomenon is attributed to the formation of nanoparticles’ aggregates that are discretely distributed in the nanofibers.
The paper describes the Version 2 of the CO2FIX (CO2FIX V.2) model, a user-friendly tool for dynamically estimating the carbon sequestration potential of forest management, agroforesty and ...afforestation projects. CO2FIX V.2 is a multi-cohort ecosystem-level model based on carbon accounting of forest stands, including forest biomass, soils and products. Carbon stored in living biomass is estimated with a forest cohort model that allows for competition, natural mortality, logging, and mortality due to logging damage. Soil carbon is modeled using five stock pools, three for litter and two for humus. The dynamics of carbon stored in wood products is simulated with a set of pools for short-, medium- and long-lived products, and includes processing efficiency, re-use of by-products, recycling, and disposal forms. The CO2FIX V.2 model estimates total carbon balance of alternative management regimes in both even and uneven-aged forests, and thus has a wide applicability for both temperate and tropical conditions. Results for the model testing and validation in selected temperate and tropical forest management systems are presented and discussed.
The CERN Axion Solar Telescope has finished its search for solar axions with (3)He buffer gas, covering the search range 0.64 eV ≲ ma ≲ 1.17 eV. This closes the gap to the cosmological hot dark ...matter limit and actually overlaps with it. From the absence of excess x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of gaγ ≲ 3.3 × 10(-10) GeV(-1) at 95% C.L., with the exact value depending on the pressure setting. Future direct solar axion searches will focus on increasing the sensitivity to smaller values of gaγ, for example by the currently discussed next generation helioscope International AXion Observatory.
Purpose
The effect of the sodium-glucose 2 (SGLT-2) inhibitors on microvascular complications remains uncertain. We performed a systematic review to determine the efficacy of the SGLT-2 inhibitors on ...microvascular outcomes in patients with type 2 diabetes.
Methods
A comprehensive search was performed using Ovid, MEDLINE, EMBASE, Web of Science, and Scopus from inception to May 2019. Randomized trials comparing SGLT-2 inhibitors with placebo or other medication for type 2 diabetes for ≥ 4 weeks were included. Diabetes-related microvascular complications such as nephropathy, retinopathy, neuropathy, and peripheral vascular disease were evaluated. A random-effect model using mean differences for continuous outcomes and risk ratio for dichotomous outcomes was used to synthesize data. PROSPERO (CRD 42017076460).
Results
A total of 40 RCTs with overall moderate quality of evidence were included. SGLT-2 inhibitors reduced the risk of renal-replacement therapy (0.65; 95% CI 0.54–0.79), renal death (0.57; 95% CI 0.49–0.65), and progression of albuminuria (0.69; 95% CI 0.66–0.73). Conversely, they appeared ineffective in maintaining eGFR (0.33; 95% CI − 0.74 to 1.41) or reducing serum creatinine (− 0.07; 95% CI − 0.26 to 0.11), whereas urine albumin–creatinine ratio (− 23.4; 95% CI − 44.6 to − 2.2) was reduced. Risk of amputation was non-significant (1.30; 95% CI 0.93–1.83). No available data were found regarding neuropathy and retinopathy to perform a quantitative analysis.
Conclusion
SGLT-2 inhibitors may reduce the risk of renal patient-important outcomes but fail to improve surrogate outcomes. Apparently, no increased risk of amputations was observed with these medications. No data were available regarding other microvascular complications.
Batch tests were carried out to investigate the production of H2 considering the effects of: substrate concentration in a range of 3–25 g-COD/L; Initial pH: from 4 to 7 and 11 and temperatures of: ...20, 35, 45 and 55 °C. The optimal substrate was 25 g-COD/L, with a reduction of COD of 73% and a yield of H2 of 5.95 mM/gCOD; and the optimal initial pH was 11.0, with a 70% of COD reduction and a H2 yield of 4236 mM/gCOD. The optimum temperature for pH = 11 was 35 °C, with a COD reduction of 69.8% and H2 yield of 6.3 mM/gCOD. Escherichia, Acinetobacter, Alcaligenes, Brevibacterium, Clostridium and Mycobacterium were isolated from pretreated inoculum samples and identified by 16S rDNA sequencing. The results suggest that biofilm reactors developed on a natural support such as Opuntia imbricata have good potential for hydrogen production from dairy wastewater.
•Anaerobic sludge useful as inoculum for H2 production.•Effects of temperature/substrate/pH on biohydrogen production and for the development of biofilms.•Chemical-thermal pretreatments against methanogens.•Metagenomic analysis of the pretreated mixed microflora.
In this study, we prepared Al2O3-TiO2 (AT) mixed oxides to synthesize NiW catalysts for sulfur removal reactions. The AT support samples were prepared with various surfactants. Additionally, gallium ...atoms (2.4 wt%) were introduced as an additive to coat the outer surface layers of AT support that lacked Al3+ or Ti2+ cations. Characterization results showed substantial differences in textural properties, chemical composition, and surface acidity. The x-ray Photoelectron Spectroscopy (XPS) and High-Resolution Transmission Electron Microscopy (HR-TEM) results demonstrated that the NiW/AT-L-Ga sample has a better combination of dispersion, sulfidation, and promotion among materials. The sulfided NiW/AT-L-Ga catalyst had the highest catalytic activity. After incorporating Ga, XPS observed that the activity could be associated with an increase in the NiWS active phase; however, including a surfactant in the synthesis of the support allowed an increase in the amount of NiWS phase. The active phase was modeled considering the HR-TEM results for the slab length, revealing the atoms at the border susceptible to promotion.
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•Development of a polysaccharide-based magnetic hybrid nanostructures is reported.•Hybrid nanostructures are composed by nanoparticles assembled into CMC template.•Magnetic relaxation ...of nanostructures can be tuned from control of their morphology.•Hysteretic characteristics depend on the mean distance among nanoparticles.
In this contribution, the development of polysaccharide-based magnetic hybrid nanostructures (HNs) is reported. A one-pot soft-chemistry approach was followed in order to obtain HNs composed by cobalt-ferrite nanoparticles (CoSNPs) that were assembled into carboxymethyl-cellulose (CMC) templates, whose size and morphology are controllable. The synthesized HNs were characterized by transmission electron microscopy, X-Ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and magnetic measuring. The experimental evidence indicates that both size and morphology of the CMC templates varies according to the CoSNPs weight content in the HNs, as well as to the hydration time of the CMC used as template. Moreover, these morphological features modify the hysteretic characteristics and thermal relaxation of the CoSNPs assemblies, due to the change on the mean distance among particles in the CMC templates. Thus, the magnetic response of these HNs can be tuned from the control of the morphology of the CMC templates where CoSNPs are assembled.
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