56 research outputs found
Concerning synthesis of new biobased polycarbonates with curcumin in replacement of bisphenol a and recycled diphenyl carbonate as example of circular economy
Curcumin (CM) is a natural polyphenol well-known for its antioxidant and pharmaceutical properties, that can represent a renewable alternative to bisphenol A (BPA) for the synthesis of biobased polycarbonates (PC). In the presented strategy, preparation of the CM-based PC was coupled with chemical recycling of the fossil-based BPA polycarbonate (BPA-PC) conducting a two-steps trans-polymerization that replaces BPA monomer with CM or its tetrahydrogenated colorless product (THCM). In the first step of synthetic strategy, depolymerization of commercial BPA-PC was carried out with phenol as nucleophile, according to our previous procedure based on zinc derivatives and ionic liquids as catalysts, thus producing quantitatively diphenyl carbonate (DPC) e BPA. In the second step, DPC underwent a melt transesterification with CM or THCM monomers affording the corresponding bio-based polycarbonates, CM-PC and THCM-PC, respectively. THCM was prepared by reducing natural bis-phenol with cyclohexene as a hydrogen donor and characterized by 1H-NMR and MS techniques. Polymerization reactions were monitored by infrared spectroscopy and average molecular weights and dispersity of the two biobased polymers THCM-PC and CM-PC were determined by means of gel permeation chromatography (GPC). Optical properties of the prepared polymers were also measured
Valorization of cigarette butts for synthesis of levulinic acid as top value-added chemicals
Unprecedented in the literature, levulinic acid (LA), one of the top value-added intermediates of chemical industry, is obtained from cigarette butts as cellulose feedstock by means of a one-pot hydrothermal process carried out at 200 °C for 2 h and catalysed by phosphoric acid. The protocol avoids the use of more aggressive and toxic H2SO4 and HCl, that are generally employed on several cellulose sources (e.g. sludge paper), thus minimizing corrosion phenomena of plants. Neither chemical pre-treatment of butts nor specific purification procedure of LA are required. Notably, by simply modifying acid catalyst (e.g. using CH3COOH), another top value-added fine chemical such as 5-hydroxymethylfuraldehyde (HMF) is obtained, thus widening the scope of the method. Being cigarette filters a waste available in quantities of megatonnes per year, they represent an unlimited at no cost source of cellulose, thus enabling the up-scale to an industrial level of LA production
Deep control of linear oligomerization of glycerol using lanthanum catalyst on mesoporous silica gel
The valorization of glycerol (1), a waste of biodiesel production of Fatty Acid Methyl Esters (FAMEs), adopting a âgreenâ approach, represents an important goal of sustainable chemistry. While the polymerization of 1 to hyperbranched oligomers is a well-established process, the linear analogues are difficult to obtain. In this context, we explore the reaction without the solvent of heterogeneous hybrid La(III)O-KIT-6 catalyst (2), which is based on lanthanum oxide on mesoporous silica gel, showing a superior linear selectivity compared to most of the analogous catalysts recently reported
Photoreduction of Carbon Dioxide to Formic Acid in Aqueous Suspension: A Comparison between Phthalocyanine/TiO2 and Porphyrin/TiO2 Catalysed Processes
Composite materials prepared by loading polycrystalline TiO2 powders with lipophilic highly branched Cu(II)- and metal-free phthalocyanines or porphyrins, which have been used in the past as photocatalysts for photodegradative processes, have been successfully tested for the efficient photoreduction of carbon dioxide in aqueous suspension affording significant amounts of formic acid. The results indicated that the presence of the sensitizers is beneficial for the photoactivity, confirming the important role of Cu(II) co-ordinated in the middle of the macrocycles. A comparison between Cu(II) phthalocyanines and Cu(II) porphyrins indicated that the Cu(II)- phthalocyanine sensitizer was more efficient in the photoreduction of CO2 to formic acid, probably due to its favorable reduction potential
Multifunctional halloysite and hectorite catalysts for effective transformation of biomass to biodiesel
Halloysite surface was modified with tetrabutylammonium iodide, and then the obtained nanomaterial was used
as support for ZnO nanoparticles. After characterization, the nanomaterial was used as a catalyst for fatty acid
methyl esters (FAMEs) production. The recyclability of the nanomaterial was also investigated, and the optimization
of reaction conditions by the design of experiments approach was performed as well. In addition, the
synthesized nanomaterial was tested as a catalyst for FAME production from a series of waste lipids affording
biodiesel in moderate to good yields (35â95%), depending on the matrix. To fully exploit the feasibility of clay
minerals as catalysts in biodiesel formation, a screening of different clays and clay minerals with different
morphologies and compositions, such as sepiolite, palygorskite, bentonite, and hectorite was also performed in
the esterification of FFAs (a mixture of 1:1 palmitic and stearic acids). Finally, hectorite, chosen as a model of 2:1
clay minerals, was covalently modified, and tested as a catalyst in the esterification of FFAs
Introduction of Probiotic-Based Sanitation in the Emergency Ward of a Children's Hospital During the COVID-19 Pandemic
Background: Antimicrobial resistance (AMR) represents a major threat to public health, especially in the hospital environment, and the massive use of disinfectants to prevent COVID-19 transmission might intensify this risk, possibly leading to future AMR pandemics. However, the control of microbial contamination is crucial in hospitals, since hospital microbiomes can cause healthcare-associated infections (HAIs), which are particularly frequent and severe in pediatric wards due to children having high susceptibility.
Aim: We have previously reported that probiotic-based sanitation (PCHS) could stably decrease pathogens and their AMR in the hospital environment, reduce associated HAIs in adult hospitals, and inactivate enveloped viruses. Here, we aimed to test the effect of PCHS in the emergency room (ER) of a children's hospital during the COVID-19 pandemic.
Methods: Conventional chemical disinfection was replaced by PCHS for 2 months during routine ER sanitation; the level of environmental bioburden was characterized before and at 2, 4, and 9 weeks after the introduction of PCHS. Microbial contamination was monitored simultaneously by conventional culture-based CFU count and molecular assays, including 16S rRNA NGS for bacteriome characterization and microarrays for the assessment of the resistome of the contaminating population. The presence of SARS-CoV-2 was also monitored by PCR.
Results and conclusions: PCHS usage was associated with a stable 80% decrease in surface pathogens compared to levels detected for chemical disinfection (P < 0.01), accompanied by an up to 2 log decrease in resistance genes (Pc < 0.01). The effects were reversed when reintroducing chemical disinfection, which counteracted the action of the PCHS. SARS-CoV-2 was not detectable in both the pre-PCHS and PCHS periods. As the control of microbial contamination is a major issue, especially during pandemic emergencies, collected data suggest that PCHS may be successfully used to control virus spread without simultaneous worsening of the AMR concern
Potential Use of a Combined BacteriophageâProbiotic Sanitation System to Control Microbial Contamination and AMR in Healthcare Settings: A Pre-Post Intervention Study
Microbial contamination in the hospital environment is a major concern for public health, since it significantly contributes to the onset of healthcare-associated infections (HAIs), which are further complicated by the alarming level of antimicrobial resistance (AMR) of HAI-associated pathogens. Chemical disinfection to control bioburden has a temporary effect and can favor the selection of resistant pathogens, as observed during the COVID-19 pandemic. Instead, probiotic-based sanitation (probiotic cleaning hygiene system, PCHS) was reported to stably abate pathogens, AMR, and HAIs. PCHS action is not rapid nor specific, being based on competitive exclusion, but the addition of lytic bacteriophages that quickly and specifically kill selected bacteria was shown to improve PCHS effectiveness. This study aimed to investigate the effect of such combined probioticâphage sanitation (PCHSÏ) in two Italian hospitals, targeting staphylococcal contamination. The results showed that PCHSÏ could provide a significantly higher removal of staphylococci, including resistant strains, compared with disinfectants (â76%, p < 0.05) and PCHS alone (â50%, p < 0.05). Extraordinary sporadic chlorine disinfection appeared compatible with PCHSÏ, while frequent routine chlorine usage inactivated the probiotic/phage components, preventing PCHSÏ action. The collected data highlight the potential of a biological sanitation for better control of the infectious risk in healthcare facilities, without worsening pollution and AMR concerns
A Novel Approach to the Efficient Oxygenation of Hydrocarbons Under Mild Conditions. Superior Oxo transfer Selectivity Using Dioxiranes
The design of efficient and general methods for the selective oxyfunctionalization
of unactivated carbon-hydrogen bonds continues
to represent a major challenge for the community of chemists,
despite the fact that the oxidation of alkanes is a major feature of
the chemical economy. A low level of selectivity is characteristic
of large-scale oxidation of hydrocarbons performed under customary
industrial oxidizing conditions (e.g., the catalytic air oxidation
of cycloalkanes); in these processes, selectivity is difficult to control,
because they are often impacted by the usual problems associated
with free-radical chain reactions. Thus, in the last decades much
work has been devoted to the search for general methods of
selective oxidation that could be applied to a variety of satured
hydrocarbons. In this context, just a few leading methods appear
encouraging at the present time. This Account addresses a new
approach developed in our laboratory, consisting in the application
of isolated dioxiranes, a class of powerful yet selective oxidants.
We contend that the method shows promise to contribute resolution
of a well-recognized general problem in the existing chemistry
of alkanes, that is, to achieve efficient oxyfunctionalizations with
high selectivity for simple as well as structurally complex targets
JOHN O. EDWARDS: MEZZO SECOLO DI CHIMICA DEI COMPOSTI PEROSSIDICI
Ă presentata una breve rassegna circa la figura e lâopera scientifica del prof. John O. Edwards
(Brown University, USA), socio onorario della SocietĂ Chimica Italiana, di recente scomparso.
Il suo notevole contributo allo sviluppo delle conoscenze nel campo delle chimica dei composti
perossidici, con particolare riguardo alla definizione dei meccanismi di ossidazione, Ăš qui riassunto
traendo lo spunto dai suoi studi sul trasferimento di ossigeno elettrofilo da perossidi a substrati
nucleofili, sulla generazione di specie radicaliche, sulla catalisi da complessi di metalli di transizione
e sulla definizione della reattivitĂ dellâelusivo acido perossonitroso
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