RESUMO
Virucidal filter materials were prepared by electrospinning a solution of 28 wt % poly(vinylidene difluoride) in N,N-dimethylacetamide without and with the addition of 0.25 wt %, 0.75 wt %, 2.0 wt %, or 3.5 wt % Cu(NO3)2 · 2.5H2O as virucidal agent. The fabricated materials had a uniform and defect free fibrous structure and even distribution of copper nanoclusters. X-ray diffraction analysis showed that during the electrospinning process, Cu(NO3)2 · 2.5H2O changed into Cu2(NO3)(OH)3. Electrospun filter materials obtained by electrospinning were essentially macroporous. Smaller pores of copper nanoclusters containing materials resulted in higher particle filtration than those without copper nanoclusters. Electrospun filter material fabricated with the addition of 2.0 wt % and 3.5 wt % of Cu(NO3)2 · 2.5H2O in a spinning solution showed significant virucidal activity, and there was 2.5 ± 0.35 and 3.2 ± 0.30 logarithmic reduction in the concentration of infectious SARS-CoV-2 within 12 h, respectively. The electrospun filter materials were stable as they retained virucidal activity for three months.
RESUMO
Highly microporous adsorbents have been under considerable scrutiny for efficient adsorptive storage of H2. Of specific interest are sustainable, chemically activated, microporous carbon adsorbents, especially from renewable and organic precursor materials. In this article, six peat-derived microporous carbon materials were synthesized by chemical activation with ZnCl2. N2 and CO2 gas adsorption data were measured and simultaneously fitted with the 2D-NLDFT-HS model. Thus, based on the obtained results, the use of a low ratio of ZnCl2 for chemical activation of peat-derived carbon yields highly ultramicroporous carbons which are able to adsorb up to 83% of the maximal adsorbed amount of adsorbed H2 already at 1 bar at 77 K. This is accompanied by the high ratio of micropores, 99%, even at high specific surface area of 1260 m2 g-1, exhibited by the peat-derived carbon activated at 973 K using a 1:2 ZnCl2 to peat mass ratio. These results show the potential of using low concentrations of ZnCl2 as an activating agent to synthesize highly ultramicroporous carbon materials with suitable pore characteristics for the efficient low-pressure adsorption of H2.
RESUMO
Scanning electron microscopy (SEM) is a powerful tool for observing microbe-mineral interactions in situ. Despite its wide usage in geomicrobiology there is no consensus on how the samples should be handled before visualizing in SEM. We compared response of artificial laboratory-grown bacterial community and natural in situ microbes on terrestrial basalt to different sample pre-treatment methods with the aim to preserve microbe-mineral interaction interface. Air-drying was the only method that maintained the location of loosely attached bacteria on a mineral surface, whereas chemical fixation and drying dislocated the cells. On the contrary, chemical fixation preserved the cellular morphology while air-drying caused the collapse of most of the laboratory-grown cells. Natural microbial communities on dry terrestrial basalt were composed of desiccation resistant microbes which remained attached to the surface and partially maintained their morphology regardless of the sample pre-treatment method. None of the tested methods allowed visualization of microbe-mineral interface in a biofilm. We suggest air-drying as a main sample pre-treatment method for visualizing microbes on mineral surfaces when loss of morphology is secondary to potentially dislocated cells and to potential chemical changes in the sample caused by the chemical fixation reagents.
