•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.
ABSTRACT
We present an infrared (IR) characterization of the born-again planetary nebulae (PNe) A 30 and A 78 using IR images and spectra. We demonstrate that the carbon-rich dust in A 30 and A 78 is ...spatially coincident with the H-poor ejecta and coexists with hot X-ray-emitting gas up to distances of 50 arcsec from the central stars of PNe (CSPNe). Dust forms immediately after the born-again event and survives for 1000 yr in the harsh environment around the CSPN as it is destroyed and pushed away by radiation pressure and dragged by hydrodynamical effects. Spitzer IRS spectral maps showed that the broad spectral features at 6.4 and 8.0 μm, attributed to amorphous carbon formed in H-deficient environments, are associated with the disrupted disc around their CSPN, providing an optimal environment for charge exchange reactions with the stellar wind that produces the soft X-ray emission of these sources. Nebular and dust properties are modelled for A 30 with cloudy taking into account different carbonaceous dust species. Our models predict dust temperatures in the 40–230 K range, five times lower than predicted by previous works. Gas and dust masses for the born-again ejecta in A 30 are estimated to be $M_\mathrm{gas}=4.41^{+0.55}_{-0.14}\times 10^{-3}$ M⊙ and $M_\mathrm{dust}=3.20^{+3.21}_{-2.06}\times 10^{-3}$ M⊙, which can be used to estimate a total ejected mass and mass-loss rate for the born-again event of $7.61^{+3.76}_{-2.20}\times 10^{-3}$ M⊙ and $\dot{M}=(5{\!-\!}60)\times 10^{-5}$ M⊙ yr−1, respectively. Taking into account the carbon trapped into dust grains, we estimate that the C/O mass ratio of the H-poor ejecta of A 30 is larger than 1, which favours the very late thermal pulse model over the alternate hypothesis of a nova-like event.
► The best photocatalytic system for EB degradation was based on TiO2–In 1%/365nm. ► A maximum EC of 290gm−3h−1 for the hybrid system was obtained. ► The hybrid process enhanced 40% the overall EC of ...ethylbenzene. ► An overall mineralization of 67% for EB degradation was reached in the hybrid system.
The use of hybrid processes for the continuous degradation of ethylbenzene (EB) vapors has been evaluated. The hybrid system consists of an UV/TiO2–In photooxidation coupled with a biofiltration process. Both the photocatalytic system using P25-Degussa or indium-doped TiO2 catalysts and the photolytic process were performed at UV-wavelengths of 254nm and 365nm. The experiments were carried out in an annular plug flow photoreactor packed with granular perlite previously impregnated with the catalysts, and in a glass biofilter packed with perlite and inoculated with a microbial consortium. Both reactors were operated at an inlet loading rate of 127gm−3h−1. The greatest degradation rate of EB (0.414ngm−2min−1) was obtained with the TiO2–In 1%/365nm photocatalytic system. The elimination capacity (EC) obtained in the control biofilter had values ∼60gm−3h−1. Consequently, the coupled system was operated for 15 days, and a maximal EC of 275gm−3h−1. Thus, the results indicate that the use of hybrid processes enhanced the EB vapor degradation and that this could be a promising technology for the abatement of recalcitrant volatile organic compounds.
•We report a green chemistry approach for the synthesis of nanofibrous materials.•Nanofibrous materials were obtained from the electrospinning technique.•We electrospun nanofibrous materials from ...blends of CMC–AgNPs/PVA using weight ratios as high as 0.48.•Nanofibers diameter decreases from 153 to 103nm as CMC weight content reaches 32.3wt%.
In this contribution a novel green chemistry approach for the synthesis of nanofibrous materials based on blends of carboxymethyl-cellulose (CMC)–silver nanoparticles (AgNPs) composite and polyvinyl-alcohol (PVA) is proposed. These nanofibrous materials were obtained from the electrospinning of blends of aqueous solutions of CMC–AgNPs composite and PVA, which were prepared at different CMC/PVA weight ratios in order to electrospin nanofibers applying a constant tension of 15kV. The synthesized materials were characterized by means of transmission electron microscopy, scanning electron microscopy; as well as Fourier-transform infrared, ultraviolet and Raman spectroscopic techniques. Experimental evidence suggests that the diameter of the nanofibers is thinner than any other reported in the literature regarding the electrospinning of CMC. This feature is related to the interactions of AgNPs with carboxyl functional groups of the CMC, which diminish those between the later and acetyl groups of PVA.
Pharmaceuticals and their by-products are recalcitrant contaminants in water. Moreover, the high consumption of these drugs has many detrimental effects on body waters and ecosystems. In this timely ...review, the advances in molecular engineering of layered double hydroxides (LDH) that have been used for the removal of pharmaceutical pollutants are discussed. The approach starts from the strategies to obtain homogeneous synthesis of LDH that allow the doping and/or surface functionalization of different metals and oxides, producing heterojunction systems as well as composites with carbon and silica-based materials with high surface area. Adsorption is considered as a traditional removal of pharmaceutical pollutants, so the kinetic and mechanism of this phenomenon are analyzed based on pH, temperature, ionic strength, in order to obtain new insights for the formation of multifunctional LDH. Advanced oxidation methodologies, mainly heterogeneous photocatalysis and Fenton-like processes, stand out as the more efficient even to obtain the mineralization of the drugs. The LDH have the advantage of structural memory that favors regeneration processes. The reconstruction of calcined LDH can be used to improve drug removal, through a combination of adsorption capacity/catalytic activity. A meticulous analysis of the persistence, toxicity and bioaccumulation of the most common pharmaceuticals has allowed us to highlight the ability of the LDH to remove recalcitrant drugs at relatively low concentrations (ppm, ppb), in contrast to other mixed oxide nanostructures and homogeneous oxidation processes. In this sense, the mechanism of drug removal by LDH is discussed based on the importance of the use of composites, scavenger agents, Fenton and electro-Fenton processes, membranes, thin films and coatings, among others. In addition, the ecotoxicity of LDH is also reviewed to indicate that these layered structures can exhibit biocompatibility or high toxicity depending on the adsorbed drug and ions/metals that compose them. Undoubtedly, the LDH have a unique flexible structure with adsorption capacity and catalytic activity, facts that explain the important reasons for their extensive use in the environmental remediation of pharmaceutical pollutants from water.
•LDH nanomaterials can resolve the actual emerging pharmaceutical pollutants issues.•The use of LDH positively affects the water cycle to overcome toxic waste.•LDH can work as an adsorbent/catalytic agent for removal of pharmaceuticals.•Reconstruction of calcined LDH can be used to improve drug removal.
Camellia sinensis
is a well-known plant used for health purposes due to its high phenolic compound content and antioxidant properties. For the first time, the infusion of green tea has allowed the ...growth and stabilization of silver nanowires (AgNWs). Two commercial types of green tea leaf extracts were used for the practical synthesis of AgNWs at low temperature. The use of low concentrations of polyvinylpyrrolidone (PVP) as a directing agent was successful to obtain nanobar/nanorod assemblies that form 2-fold to 10-fold nanowires. FESEM, HRTEM and HAADF microscopies helped identify nanowires of ∼50 nm in diameter and ∼1.3 micron in length. The antibacterial properties of the AgNWs were investigated against
Escherichia coli
and
Staphylococcus aureus
. The AgNW morphology may damage the cell wall, accelerating cellular stress that leads to fatal inactivation of infectious microorganisms. This work provides a green approach to the aqueous biosynthesis of AgNWs with promising antibacterial properties.
Camellia sinensis
is a well-known plant used for health purposes due to its high phenolic compound content and antioxidant properties.
ABSTRACT
We here present the results of an analysis of the optical spectroscopy of 42 globular cluster (GC) candidates in the nearby spiral galaxy M81 (3.61 Mpc). The spectra were obtained using the ...long-slit and multi-object spectroscopic modes of the OSIRIS instrument at the 10.4-m Gran Telescopio Canarias at a spectral resolution of ∼1000. We used the classical H β versus MgFe′ index diagram to separate genuine old GCs from clusters younger than 3 Gyr. Of the 30 spectra with continuum signal-to-noise ratio >10, we confirm 17 objects to be classical GCs (age >10 Gyr, −1.4 < Fe/H < −0.4), with the remaining 13 being intermediate-age clusters (1–7.5 Gyr). We combined age and metallicity data of other nearby spiral galaxies (≲18 Mpc) obtained using similar methodology like the one we have used here to understand the origin of GCs in spiral galaxies in the cosmological context. We find that the metal-poor (Fe/H < −1) GCs continued to form up to 6 Gyr after the first GCs were formed, with all younger systems (age <8 Gyr) being metal rich.
In the present research work, the photocatalytic evaluation of NiTiO3 nanoparticles immobilized on glass plates by the spin-coating procedure was carried out in the degradation of the recalcitrant ...herbicide 2,6-dichlorobenzamide (BAM). The concentrations of Ni employed to synthesize NiTiO3 nanoparticles were 1 wt% (1TESNi) and 2 wt% (2TESNi). The stability of coatings was evaluated by several washings and thermal treatments, which were verified by UV–vis analyses. The morphology of the coatings was studied by scanning electron microscopy (SEM-EDS). The coatings displayed thickness values of 1.35 and 2.56 μm for TiO2 and 1TESNi, respectively. The crystalline phases of the coatings were analyzed by X-ray diffraction (XRD), confirming the presence of NiTiO3 and other phases related to TiO2. The bandgap of 1TESNi, compared with the bare TiO2, was reduced from 2.96 to 2.40 eV as a consequence of Ni addition. The TiO2, 1TESNi and 2TESNi coatings were evaluated in the photodegradation of BAM using visible-light for 240 min. The highest effectiveness was displayed by the 1TESNi coating, obtaining degradation of 92.56% after 240 min. Also, the photocatalytic efficiency of the 1TESNi coating was only reduced 1.99% after 3 reuse cycles in the BAM degradation. The scavenger tests revealed that the main oxidizing species involved in the reaction were the •OH− and •O2− radicals. The 1TESNi coating showed the highest photocatalytic efficiency because of its absorption in the visible-light region, valuable surface area and electronic charge separation. Thus, these advantageous features guarantee that NiTiO3 coatings are an efficient method for degrading recalcitrant herbicides from drinking water using a practical way to recover and reuse photocatalysts.
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•Photoefficient NiTiO3 NPs were immobilized on glass substrates by spin coating.•NiTiO3 coatings achieved the highest BAM photocatalytic degradation of 92.62%.•After 3 reuses, NiTiO3 coatings were 8.4% more efficient than powders.••OH− and •O2− were the main oxidizing species produced by the photocatalyst.•Photoactive and practical NiTiO3 coatings allowed reuse and manual recovery.
Summary Background The best available treatment against carbapenemase-producing Enterobacteriaceae (CPE) is unknown. The objective of this study was to investigate the effect of appropriate therapy ...and of appropriate combination therapy on mortality of patients with bloodstream infections (BSIs) due to CPE. Methods In this retrospective cohort study, we included patients with clinically significant monomicrobial BSIs due to CPE from the INCREMENT cohort, recruited from 26 tertiary hospitals in ten countries. Exclusion criteria were missing key data, death sooner than 24 h after the index date, therapy with an active antibiotic for at least 2 days when blood cultures were taken, and subsequent episodes in the same patient. We compared 30 day all-cause mortality between patients receiving appropriate (including an active drug against the blood isolate and started in the first 5 days after infection) or inappropriate therapy, and for patients receiving appropriate therapy, between those receiving active monotherapy (only one active drug) or combination therapy (more than one). We used a propensity score for receiving combination therapy and a validated mortality score (INCREMENT-CPE mortality score) to control for confounders in Cox regression analyses. We stratified analyses of combination therapy according to INCREMENT-CPE mortality score (0–7 low mortality score vs 8–15 high mortality score). INCREMENT is registered with ClinicalTrials.gov , number NCT01764490. Findings Between Jan 1, 2004, and Dec 31, 2013, 480 patients with BSIs due to CPE were enrolled in the INCREMENT cohort, of whom we included 437 (91%) in this study. 343 (78%) patients received appropriate therapy compared with 94 (22%) who received inappropriate therapy. The most frequent organism was Klebsiella pneumoniae (375 86% of 437; 291 85% of 343 patients receiving appropriate therapy vs 84 89% of 94 receiving inappropriate therapy) and the most frequent carbapenemase was K pneumoniae carbapenemase (329 75%; 253 74% vs 76 81%). Appropriate therapy was associated with lower mortality than was inappropriate therapy (132 38·5% of 343 patients died vs 57 60·6% of 94; absolute difference 22·1% 95% CI 11·0–33·3; adjusted hazard ratio HR 0·45 95% CI 0·33–0·62; p<0·0001). Among those receiving appropriate therapy, 135 (39%) received combination therapy and 208 (61%) received monotherapy. Overall mortality was not different between those receiving combination therapy or monotherapy (47 35% of 135 vs 85 41% of 208; adjusted HR 1·63 95% CI 0·67–3·91; p=0·28). However, combination therapy was associated with lower mortality than was monotherapy in the high-mortality-score stratum (30 48% of 63 vs 64 62% of 103; adjusted HR 0·56 0·34–0·91; p=0·02), but not in the low-mortality-score stratum (17 24% of 72 vs 21 20% of 105; adjusted odds ratio 1·21 0·56–2·56; p=0·62). Interpretation Appropriate therapy was associated with a protective effect on mortality among patients with BSIs due to CPE. Combination therapy was associated with improved survival only in patients with a high mortality score. Patients with BSIs due to CPE should receive active therapy as soon as they are diagnosed, and monotherapy should be considered for those in the low-mortality-score stratum. Funding Spanish Network for Research in Infectious Diseases, European Development Regional Fund, Instituto de Salud Carlos III, and Innovative Medicines Initiative.
In this article, a mathematical microbial electrochemical cell (MEC) dynamic model is proposed. The model is derived from mass balances of a continuous flow MEC system which consists of two ...interconnected chambers. The system is described by a set of nonlinear ordinary differential equations (ODEs) that describes: (i) the competition of anodophilic and methanogenic microbial populations for a common substrate and; (ii) biomass growth and retention in the anodic compartment. Open loop behavior is evaluated via numerical simulations. The model is suitable both for process optimization and online control applications. Parametric sensitivity, stability, and convergence properties of the proposed model are also addressed in this article.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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