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Characterization of aerosol and assessment of the risk of transmission of SARS-COV-2 VIRUS in a natural thermal cave
Thermal caves represent an environment characterized by unique chemical-physical properties, often used by customers for treatment and care of musculoskeletal, respiratory and skin diseases. The recent pandemic caused by COVID-19 has imposed the need to investigate the potential transmission scenario of SARS-CoV-2 virus also in such atypical and poorly studied indoor environments. This research work was carried out inside a natural thermal cave located in Italy where a waterfall of sulfur-sulfate-bicarbonate-alkaline earth mineral thermal water creates a warm-humid environment with 100% humidity and 48°C temperature. A characterization of the aerosol was carried out in terms of number, surface area and mass, as well as particle size distributions. The physical characteristics of the aerosol were measured inside the natural thermal cave and in other immediately adjacent areas in two different days and in two distinct moments by means of an optical spectrometer. The data obtained showed a predominance of particles with a diameter greater than 8 µm, associated with a low ability of penetration in the human respiratory system. Subsequently, through a model recently proposed in scientific literature, it was evaluated the airborne transmission risk of SARS-CoV-2 inside the cave by quantifying the probability of infection due to exposure in a microenvironment in presence of a SARS-CoV-2 infected subject. The infection risk was evaluated for different scenarios obtained combining parameters such as physical, breathing or talking activities of the occupants, simultaneous or non-simultaneous access to the cave and mechanical ventilation activated or non-activated. In terms of the risk of SARS-CoV-2 infection, evaluated under the hypotheses of the model, it was highlighted the decisive effect of the mechanical ventilation system on the risk of contagion: for all the hypothesized scenarios, there is a substantial reduction in the risk of contagion considering the ventilation system active. Furthermore, the adoption of social distancing measures such as non-simultaneous access to the cave makes the risk of contagion extremely low, according to the assumptions underlying the model, even with the mechanical ventilation system not active
The role of sustainability performance after merger and acquisition deals in short and long-term
A generalization of the EBA4SUB rainfall-runoff model considering surface and subsurface flow
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The bioactive profile of lettuce produced in a closed soilless system as configured by combinatorial effects of genotype and macrocation supply composition
Liposome-Embedding Silicon Microparticle for Oxaliplatin Delivery in Tumor Chemotherapy
Mesoporous silicon microparticles (MSMPs) can incorporate drug-carrying nanoparticles (NPs) into their pores. An NP-loaded MSMP is a multistage vector (MSV) that forms a Matryoshka-like structure that protects the therapeutic cargo from degradation and prevents its dilution in the circulation during delivery to tumor cells. We developed an MSV constituted by 1 µm discoidal MSMPs embedded with PEGylated liposomes containing oxaliplatin (oxa) which is a therapeutic agent for colorectal cancer (CRC). To obtain extra-small liposomes able to fit the 60 nm pores of MSMP, we tested several liposomal formulations, and identified two optimal compositions, with a prevalence of the rigid lipid 1,2-distearoyl-sn-glycero-3-phosphocholine and of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000]. To improve the MSV assembly, we optimized the liposome-loading inside the MSMP and achieved a five-fold increase of the payload using an innovative lyophilization approach. This procedure also increased the load and limited dimensional changes of the liposomes released from the MSV in vitro. Lastly, we found that the cytotoxic efficacy of oxa-loaded liposomes and-oxa-liposome-MSV in CRC cell culture was similar to that of free oxa. This study increases knowledge about extra-small liposomes and their loading into porous materials and provides useful hints about alternative strategies for designing drug-encapsulating NPs.s