The need to secure public health and mitigate the environmental impact associated with the massified use of respiratory protective devices (RPD) has been raising awareness for the safe reuse of ...decontaminated masks by individuals and organizations. Among the decontamination treatments proposed, in this work, three methods with the potential to be adopted by households and organizations of different sizes were analysed: contact with nebulized hydrogen peroxide (H2O2); immersion in commercial bleach (NaClO) (sodium hypochlorite, 0.1% p/v); and contact with steam in microwave steam-sanitizing bags (steam bag). Their decontamination effectiveness was assessed using reference microorganisms following international standards (issued by ISO and FDA). Furthermore, the impact on filtration efficiency, air permeability and several physicochemical and structural characteristics of the masks, were evaluated for untreated masks and after 1, 5 and 10 cycles of treatment. Three types of RPD were analysed: surgical, KN95, and cloth masks. Results demonstrated that the H2O2 protocol sterilized KN95 and surgical masks (reduction of >6 log10 CFUs) and disinfected cloth masks (reduction of >3 log10 CFUs). The NaClO protocol sterilized surgical masks, and disinfected KN95 and cloth masks. Steam bags sterilized KN95 and disinfected surgical and cloth masks. No relevant impact was observed on filtration efficiency.
Pb(II) biosorption onto algae
Gelidium, algal waste from agar extraction industry and a composite material was studied. Discrete and continuous site distribution models were used to describe the ...biosorption equilibrium at different pH (5.3, 4 and 3), considering competition among Pb(II) ions and protons. The affinity distribution function of Pb(II) on the active sites was calculated by the Sips distribution. The Langmuir equilibrium constant was compared with the apparent affinity calculated by the discrete model, showing higher affinity for lead ions at higher pH values.
Kinetic experiments were conducted at initial Pb(II) concentrations of 29–104
mg
l
−1 and data fitted to pseudo-first Lagergren and second-order models.
The adsorptive behaviour of biosorbent particles was modelled using a batch mass transfer kinetic model, which successfully predicts Pb(II) concentration profiles at different initial lead concentration and pH, and provides significant insights on the biosorbents performance. Average values of homogeneous diffusivity,
D
h, are 3.6
×
10
−8; 6.1
×
10
−8 and 2.4
×
10
−8
cm
2
s
−1, respectively, for
Gelidium, algal waste and composite material. The concentration of lead inside biosorbent particles follows a parabolic profile that becomes linear near equilibrium.
In this study an industrial algal waste from agar extraction has been used as an inexpensive and effective biosorbent for cadmium (II) removal from aqueous solutions. This biosorbent was compared ...with the algae
Gelidium itself, which is the raw material for agar extraction. Equilibrium data follow both Langmuir and Redlich–Peterson models. The parameters of Langmuir equilibrium model are
q
max
=
1
8.0
mg
g
-
1
,
b
=
0.1
9
mg
l
-
1
and
q
max
=
9.7
mg
g
-
1
,
b
=
0.1
6
mg
l
-
1
, respectively for
Gelidium and the algal waste. Kinetic experiments were conducted at initial Cd(II) concentrations in the range 6–91
mg
l
−1. Data were fitted to pseudo-first- and second-order Lagergren models. For an initial Cd(II) concentration of 91
mg
l
−1 the parameters of the pseudo-first-order Lagergren model are
k
1
,
ads
=
0.1
7
and 0.87
min
−1;
q
eq
=
1
6.3
and 8.7
mg
g
−1, respectively, for
Gelidium and algal waste. Kinetic constants vary with the initial metal concentration. The adsorptive behaviour of biosorbent particles was modelled using a batch reactor mass transfer kinetic model. The model successfully predicts Cd(II) concentration profiles and provides significant insights on the biosorbents performance. The homogeneous diffusivity,
D
h, is in the range 0.5–2.2×10
−8 and 2.1–10.4×10
−8
cm
2
s
−1, respectively, for
Gelidium and algal waste.
Biosorption of Pb(II), Cu(II), Cd(II) and Zn(II) from binary metal solutions onto the algae
Gelidium sesquipedale, an algal industrial waste and a waste-based composite material was investigated at ...pH 5.3, in a batch system. Binary Pb(II)/Cu(II), Pb(II)/Cd(II) and Pb(II)/Zn(II) solutions have been tested. For the same equilibrium concentrations of both metal ions (1
mmol
l
−1), approximately 66, 85 and 86% of the total uptake capacity of the biosorbents is taken by lead ions in the systems Pb(II)/Cu(II), Pb(II)/Cd(II) and Pb(II)/Zn(II), respectively. Two-metal results were fitted to a discrete and a continuous model, showing the inhibition of the primary metal biosorption by the co-cation. The model parameters suggest that Cd(II) and Zn(II) have the same decreasing effect on the Pb(II) uptake capacity. The uptake of Pb(II) was highly sensitive to the presence of Cu(II). From the discrete model it was possible to obtain the Langmuir affinity constant for Pb(II) biosorption. The presence of the co-cations decreases the apparent affinity of Pb(II). The experimental results were successfully fitted by the continuous model, at different pH values, for each biosorbent. The following sequence for the equilibrium affinity constants was found: Pb
>
Cu
>
Cd
≈
Zn.
The present work investigated whether the number of rats housed in a cage affects exploration of an elevated plus-maze. Male Wistar-derived rats were kept 1, 2, 3, 4, 6, 8, 12, 16, or 24 to same size ...cages either for 1 or 14 days and tested in the elevated plus-maze. Rats kept 6 to a cage were arbitrarily considered controls because this is the housing condition adopted in many laboratories, ours included. In comparison to controls, 1-day housed rats kept 1, 2, 16, and 24 to a cage decreased the percentage of entries into the open arms. Similar decreases were also found in the time spent in the open arms, the only exception being the group with rats kept 16 to a cage which failed to show significant differences from the control group. Fourteen-day housed rats kept 1, 2, 16, or 24 to a cage decreased the percentage of entries and time spent in the open arms. We found plus-maze exploration to be similar in groups in which rats were kept from 4 to 12 to a cage. The present data indicate that anxiogenic effects resulting from under- and overcrowding should be taken into consideration in behavioral studies.
► Biosorption of Ni(II) on various chemically modified brown algae was investigated. ► Na-algae prepared from raw algae showed the highest uptake of Ni(II). ► Biosorption involved ion-exchange ...between Na and Ni ions with stoichiometry 2:1. ► Parameter for total binding strength (ξ) was found to be, Ni>Mg>Ca>K>Na.
In the present work, various forms of algae Pelvetia canaliculata were prepared by different chemical modifications, in order to get the best form of algae for the maximum uptake of nickel. Potentiometric titration revealed that the carboxyl groups were more abundant (3.9mmol/g) as compared to hydroxyl groups (2.0mmol/g) on the biosorbent surface. Fourier transform infrared (FTIR) analysis of algae was done to identify the role of different functional groups present on algae surface during nickel biosorption. The protonated algae showed least sorption of nickel suggesting that after acid treatment, some of the binding sites were destroyed. Among the various forms of prepared algae, Na-algae prepared directly from raw algae (without protonation) showed highest uptake of nickel. The release of sodium ions during the uptake of nickel ions has shown that the current biosorption mechanism involves ion-exchange being a stoichiometrical ratio of 2:1 between sodium and nickel ions.
In the context of developing the circular economy that enables a more sustainable use of the available resources and minimum waste generation, marine macroalgae have attracted the attention of ...researchers and industry due to its potential as a renewable resource. The current work aims to contribute to the design of a complete biorefinery processing, using Fucus spiralis seaweed (brown division) as starting material, and to determine the potential of the derived waste as biosorbent of heavy metals in aqueous solution. The macroalgae waste was obtained after the sequential separation of polyphenols, fucoidan and alginate extracts from F. spiralis. The capacity of F. spiralis waste for Pb(II) removal was successfully tested through biosorption tests. The uptake of Pb(II) was found to be very fast (few hours to achieve equilibrium). Tests performed with an initial metal concentration of 20 mg/L established the best adsorbent dosage (0.50 g/L) and an optimum pH of 4.5. In these conditions, lead was almost completely removed from the aqueous solution. Maximum adsorption capacity predicted by Langmuir model was 132 ± 14 mg/g (pH 4.5 ± 0.5, 20 °C). Desorption studies were conducted with different possible eluents. The best results were obtained with EDTA 0.1 mol/L, generating a 95 ± 4% desorption. F. spiralis biomass can therefore be submitted to a complete biorefinery processing and design in the attempt to fulfil the “zero-waste” concept.
Display omitted
•A biorefinery macroalgae waste was successfully used to uptake lead from water.•Total Pb removal can be achieved using a low biosorbent dosage.•EDTA and HNO3 solutions are suitable eluents for Pb recovery.•This work contributes to the attempt to fulfil “zero-waste” in biorefinery.
In this work we present results of the first Townsend coefficient (α) in pure isobutane by measuring the current growth as a function of the electric field strength in a pulsed irradiation regime. A ...Resistive Plate Chamber (RPC)-like configuration was used. To validate this method, as well as to crosscheck the experimental apparatus, measurements of the α parameter were firstly carried out with pure nitrogen and the results compared to the accurate data available in the literature. The data obtained with isobutane in a field range from 145Td up to 200Td were well-matched to those calculated with Magboltz versions 2.7.1 and 2.8.6. The experimental consistency of these results with other published data in the range of 550–1300Td was very good, as demonstrated by the use of the Korff parameterization.
Gathering information on electric energy consumption is important for companies and institutions aiding in making plans. Multi-agent systems can aid such companies in understanding the different ...behaviours presented within the context of a society constituted by autonomous entities. We propose a multi-agent simulator capable of emulating different profiles of consumers and equipment. Our approach differs from others in three fundamental aspects: i). it models parameters that are difficult to predict, which are calibrated using values provided by available records; ii). it can be applied to different simulation environments involving various degrees of scalability and heterogeneity of profiles both of individual behaviour and household appliances; iii). it simulates the complexity of the system, providing estimates through the simulation of the interaction between users and electrical appliances. The results obtained by the model were similar to the numbers provided by the literature, which suggests the validity of the proposed approach.
Summary
The aim of this study was to isolate yeasts from the faeces of urban bats inhabiting the city of Londrina, Paraná, Brazil and to determine their potential virulence attributes. Seven (12.3%) ...of 57 bats screened in this study showed yeasts in their faeces. Five species of the genus Candida were isolated: C. guilliermondii, C. krusei, C. lusitaniae, C. parapsilosis, and C. pelliculosa. No phospholipase activity was detected in the egg yolk plate assay; however, all isolates demonstrated protease secretion in skim milk agar. Yeasts isolated from bats produced biofilm on the surface of polystyrene plates and all were classified as intermediate biofilm producers. Minimal inhibitory concentration (MIC) values for fluconazole in the yeasts varied according to the species. Only one isolate (M34 – C. lusitaniae) was considered susceptible dose‐dependent to fluconazole. The yeasts were injected intravenously into Swiss mice, and at 15 days post‐infection, the animals were killed and portions of their kidneys cultured on Sabouraud dextrose agar medium. All tissues analysed showed positive cultures of Candida spp. This is the first study evaluating the presence of fungi in the faeces of bats in an urban region, where the yeast species found were shown to be potentially pathogenic. As bats are commonly found in cities, these findings indicate the need for continuous surveillance concerning environmental contamination by their excreta.
