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The ongoing COVID-19 pandemic requires wearing face masks in many areas of our daily life; hence, the potential side effects of mask use are discussed. Therefore, the present study explores whether wearing a medical face mask (MedMask) affects physical working capacity (PWC). Secondary, the influence of a filtering facepiece mask with exhalation valve class 2 (FFP2exhal) and a cotton fabric mask (community mask) on PWC was also investigated. Furthermore, corresponding physiological and subjective responses when wearing face masks as well as a potential moderating role of subjects’ individual cardiorespiratory fitness and sex on face mask effects were analyzed. Thirty-nine subjects (20 males, 19 females) with different cardiorespiratory fitness levels participated in a standardized submaximal bicycle ergometer protocol using either a MedMask, FFP2exhal, community mask, or no mask (control) on four days, in randomized order. PWC130 and PWC150 as the mechanical load at the heart rates of 130 and 150 beats per minute were measured as well as transcutaneous carbon dioxide partial pressure, saturation of peripheral capillary oxygen, breathing frequency, blood pressure, perceived respiratory effort, and physical exhaustion. Using the MedMask did not lead to changes in PWC or physiological response compared to control. Neither appeared changes exceeding normal ranges when the FFP2exhal or community mask was worn. Perceived respiratory effort was up to one point higher (zero-to-ten Likert scale) when using face masks (p < 0.05) compared to control. Sex and cardiorespiratory fitness were not factors influencing the effects of the masks. The results of the present study provide reason to believe that wearing face masks for infection prevention during the COVID-19 pandemic does not pose relevant additional physical demands on the user although some more respiratory effort is required.

The ongoing COVID-19 pandemic requires wearing face masks in many areas of our daily life; hence, the potential side effects of mask use are discussed. Therefore, the present study explores whether wearing a medical face mask (MedMask) affects physical working capacity (PWC). Secondary, the influence of a filtering facepiece mask with exhalation valve class 2 (FFP2exhal) and a cotton fabric mask (community mask) on PWC was also investigated. Furthermore, corresponding physiological and subjective responses when wearing face masks as well as a potential moderating role of subjects’ individual cardiorespiratory fitness and sex on face mask effects were analyzed. Thirty-nine subjects (20 males, 19 females) with different cardiorespiratory fitness levels participated in a standardized submaximal bicycle ergometer protocol using either a MedMask, FFP2exhal, community mask, or no mask (control) on four days, in randomized order. PWC130 and PWC150 as the mechanical load at the heart rates of 130 and 150 beats per minute were measured as well as transcutaneous carbon dioxide partial pressure, saturation of peripheral capillary oxygen, breathing frequency, blood pressure, perceived respiratory effort, and physical exhaustion. Using the MedMask did not lead to changes in PWC or physiological response compared to control. Neither appeared changes exceeding normal ranges when the FFP2exhal or community mask was worn. Perceived respiratory effort was up to one point higher (zero-to-ten Likert scale) when using face masks (p < 0.05) compared to control. Sex and cardiorespiratory fitness were not factors influencing the effects of the masks. The results of the present study provide reason to believe that wearing face masks for infection prevention during the COVID-19 pandemic does not pose relevant additional physical demands on the user although some more respiratory effort is required.

Commercial polyether polyols are usually obtained by the ring-opening polymerization of epoxides or tetrahydrofuran. 2-Methyl-tetrahydrofuran (2-MeTHF) could be an alternative bio-based building block for the synthesis of these polyols. Although 2-MeTHF cannot be polymerized, we did achieve the copolymerization of 2-MeTHF with propylene oxide (PO) using Lewis and Brønsted acids as catalysts and water or diols as initiators. The resulting polyether polyols have a molecular weight range, which allows their use as components for adhesives. The molar content of 2-MeTHF in the oligomers can be up to 48%. A 1:1 copolymer of 2-MeTHF and PO is produced when stoichiometric amounts of BF3·OEt2 are used. Here, the monomeric units in the chains alternate, but also cyclic or other nondiol products are formed that are detrimental to its further use in adhesives. Linear dihydroxyl-terminated polyether chains were formed when the heteropolyacid H3PW12O40·24H2O was used as a catalyst and a diol as an initiator. The formation of cyclic products can be drastically reduced when the accumulation of propylene oxide during the reaction is avoided. 1H NMR experiments indicate that the step of 2-MeTHF incorporation is the alkylation of 2-MeTHF by protonated PO. It was shown that the 2-MeTHF/PO copolymer had increased tensile strength compared to polypropylene glycol in a two-component adhesive formulation.

Novel polyester polyols were prepared in high yields from biobased 1,4‐pentanediol catalyzed by non‐toxic phosphoric acid without using a solvent. These oligomers are terminated with hydroxyl groups and have low residual acid content, making them suitable for use in adhesives by polyurethane formation. The thermal behavior of the polyols was studied by differential scanning calorimetry, and tensile testing was performed on the derived polyurethanes. The results were compared with those of polyurethanes obtained with fossil‐based 1,4‐butanediol polyester polyols. Surprisingly, it was found that a crystalline polyester was obtained when aliphatic long‐chain diacids (>C12) were used as the diacid building block. The low melting point of the C12 diacid‐based material allows the development of biobased shape‐memory polymers with very low switching temperatures (, Adhesives are going green! 1,4‐Pentanediol obtained through hydrogenation of γ‐valerolactone can be efficiently converted to 100 % biobased polyester polyols. These oligomers provide added value beyond renewability in adhesive and polyurethane applications.

In EDLCs the energy is stored in the double layer formed by the ions of the electrolyte. Hence, during charge–discharge the ion concentration changes and therefore also the electrolyte should be considered as active material. In the past it has been shown that the performance of EDLCs based on non-aqueous electrolytes is mainly limited by ion concentration of the electrolytes. Taking this point into account, we considered the influence of the salt concentration on the theoretical and practical energy of high voltage EDLCs containing innovative electrolytes with the aim to understand the advantages and the limits related to their use.

Carbon coated iron oxide nanoparticles (α-Fe 2 O 3 , cIO) obtained from ferrocene display very promising performance in terms of both, capacity retention at high current density and cycling stability. Because of these characteristics, cIO can be considered as interesting material for the realization of high energy lithium-ion capacitors (LICs). In this work we investigated for the first time the use of this conversion electrode in LICs. We showed that the use of cIO enables the realization of LICs with an operative voltage of 3.4 V, able to display promising values of energy and power. However, due to a degradation process occurring on the cIO electrode, the cycling stability of the investigated LIC was limited to some thousand of cycles. Taking into account these results, it is evident that in order to develop cIO-based LICs the improvement of the cycle life of these LICs is presently the main challenge that needs to be overcome.

Supercapacitors are nowadays considered to be one of the most important electrochemical storage devices. These devices display high power and extraordinary cycle life, and they are currently used in an increasing number of applications. However, in order to further increase the applications of supercapacitors, an increase in their energy capacity appears to be necessary. Moreover, the development of safe and environmentally friendly supercapacitors is also required. In this article, we illustrate the contributions ionic liquids (ILs) might play in the development of high energy and safe supercapacitors. First, the use of ILs as electrolytes in supercapacitors is considered, and the advantages as well as challenges related to the use of this kind of electrolyte are analyzed. Next, the interaction between ILs and electrode materials is taken into account, with particular attention paid to inactive components of supercapacitor electrodes. The introduction of natural cellulose as a binder is used as an example of the contribution ILs might provide to the development of environmentally friendly supercapacitors.

Ferrocene can be used as a precursor for the synthesis of carbon-coated α-Fe2O3 nano-particles. The pyrolysis of ferrocene leads to the formation of a compound that can be fully converted into carbon-coated α-Fe2O3 nano-particles via a simple oxidation in air. This simple, fast and cheap synthetic route enables the realization of carbon-coated nano-particles with particle size in the range of 50–150 nm. Moreover, varying the oxidation temperature, it is possible to control precisely the carbon coating present on the nano-particles. The so obtained carbon-coated α-Fe2O3 nano-particles can be easily processed in water to realize composite electrodes with a composition suitable for practical application. When used in combination with conventional electrolytes such electrodes display high specific capacity (over 800 mAh g−1 at 0.13 A g−1), excellent cycling retention (higher than 99% after 50 cycles), and remarkable rate performance (over 400 mAh g−1 at 5 A g−1).

In this paper we report on the use of 0.7 M Et4NBF4 in ADN as electrolyte in EDLCs. 0.7 M Et4NBF4 in ADN displays a wide electrochemical stability window and promising values of conductivity and viscosity. Using this electrolyte it is possible to realize EDLCs with an operative voltage as high as 3.75 V. At RT, these high voltage EDLCs display high coulombic efficiencies, low ESRs and high specific capacitances stable for several thousands of cycles. The wide electrochemical stability of ADN contributes to preserve the integrity of the electrolyte at potentials in which other conventional organic electrolytes (e.g. ACN) are normally subject to deterioration and/or decomposition processes. Thanks to this intrinsic stability, EDLCs containing 0.7 M Et4NBF4 ADN as electrolyte display high capacitance retention over 35,000 cycles carried out with cell voltage as high as 3.5 V.

International audience; In the last years protic ionic liquids (PILs) have been proposed as novel electrolytes for supercapacitors. Nevertheless, so far the long term cycling stability of PIL-based supercapacitors has never been investigated in detail. Since high cycling stability is essential for such devices, a study about this aspect appears therefore of importance to understand the advantages and the limits of PIL-based systems. In this work we showed that using PILs as electrolytes it is possible to realize electrochemical double layer capacitors (EDLCs) with operative voltage as high as 2.4 V, able to feature good cycling stability in a broad range of temperature. Moreover, we also showed that the pseudo-capacitive behavior of activated carbon (ACs) in these electrolytes strongly depends on the water content and on the surface groups present on the ACs. When PILs with a lower content of water were used in combination with AC containing few surface groups, PIL-based supercapacitors exhibit specific capacitance comparable to classical organic electrolytes without any evident pseudo-capacitive contribution.

International audience; This study describes the use of mixtures of the ionic liquid (IL) trimethyl-sulfonium bis[(trifluoromethyl)sulfonyl]imide (Me3STFSI) and propylene carbonate (PC) as electrolytes for carbon-based electrochemical double layer capacitors (EDLCs). Two different mixtures have been investigated. The first one contained the maximum amount of Me3STFSI (3.8 mol L−1) soluble in PC at room temperature (RT). The second one contained 1.9 mol L−1 of Me3STFSI, which is the concentration featuring the highest conductivity among all possible mixtures between PC and Me3STFSI at RT. The physicochemical properties, including conductivity, viscosity, and electrochemical and thermal stability of both mixtures, have been initially investigated. Afterward, the use of these mixtures as electrolytes for EDLCs has been considered. This study showed that by using these innovative electrolytes, it is possible to develop EDLCs with an operative voltage as high as 3.0 V. It was clearly demonstrated that the EDLC cycle life strongly depends on the concentration of Me3STFSI present in the mixture. Moreover, it was also proved that mixtures containing high concentrations of IL are able to suppress anodic oxidation of the Al current collector at high potential. When a solution with a high salt concentration is used, an EDLC with high energy, high cycle life and a broad temperature range of operation can be realized.

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The electrochemical lithiation–delithiation of iron oxide is a rather complex process, which is still not fully understood. In this study we investigated the electrochemical lithiation–delithiation mechanism of hematite by means of X-ray diffraction (XRD), 57Fe Mossbauer spectroscopy, high-resolution transmission electron microscopy (HRTEM) and X-ray absorption spectroscopy (XAS). Since the delithiation process has been so far less investigated, particular attention was dedicated to the characterization of the chemical species that are formed during this process. The results of this investigation indicated that at the end of the delithiation process lithium iron oxide α-LiFeO2 is formed. The formation of this compound may be the explanation for the irreversible capacity loss in the first cycle, which is usually assigned to the formation of an organic gel-like layer. Based on these results a new charge–discharge mechanism of hematite in lithium-ion batteries (LIBs) is proposed and discussed.

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