Curie Temperatures and Emplacement Conditions of Pyroclastic Deposits From Popocatépetl Volcano, Mexico

Most pyroclastic deposits of Popocatépetl volcano were emplaced at high temperatures and have similar mafic to more evolved compositions, suggesting a long-lived, interconnected magma environment. We performed a magnetic and microscopic study on different eruptive sequences <14 ky in age and found that temperature and field dependence of magnetic susceptibility are suited to separate eruption phases. We observed homogeneous titanomagnetite with Curie temperatures (T$_{C}$) of 50–200°C and 200–400°C, together with different amounts of oxy-exsolved titanomagnetite with T$_{C}$ ∼ 570°C. Some block-and-ash flow deposits show remarkably irreversible T$_{C}$ in heating and cooling branches with a positive ΔT$_{C}$ (T$_{C}$ $_{heating}$ –T$_{C}$ $_{cooling}$) of up to 130°C in the center. The central part of this sequence is characterized by decreasing magnetic susceptibility and low field dependence of magnetic susceptibility (<10%), which is atypical for ulvöspinel-rich titanomagnetite. The nonreversibility of heating and cooling runs measured with rates of around 10 K/min is probably related to vacancy-enhanced nanoscale chemical clustering, which seems to occur preferentially during rapid quenching, possibly combined with subtle maghemitization. In contrast, pumice layers have the highest field dependence (∼20%) and contain Ti-rich and intermediate titanomagnetite with T$_{C}$ < 100 and ∼300°C, which are in line with mafic and more evolved magma composition. In intermediate phases, irreversibility of T$_{C}$ is more common but with a relatively low ΔT$_{C}$ of ±20°C. We suggest that magneto-mineralogy in pyroclastic density currents is complex but offers a complementary tool to the paleomagnetic directional analysis for emplacement temperature and contribute information on the volcanic material history and their emplacement conditions

The influence of oral health status on speech intelligibility, articulation and quality of life of older community-dwelling people

Objective: To investigate the impact of the oral health status on speech intelligibility, articulation and quality of life of older community-dwelling people. Background To our knowledge, there have been no studies on this topic in patients aged 75 years or older. Material and methods: Thirty outpatients of a university dental clinic (median [IQR] age of 77.00 [75-82] years) participated. The OHIP-14, a dental examination, a speech intelligibility study and an articulation examination were conducted. Results: Distortions of rhotacisms and sigmatisms were most common, followed by distortions of labiodentals and apicoalveolars. Seven participants (23%) required dental treatment. Distortions of rhotacisms were lowest in participants with loss of teeth in the posterior part of the maxilla and equal in participants with edentulous maxilla and loss of teeth in the anterior part of the maxilla (P = 0.014). Labiodental distortions were lowest in participants with loss of teeth in the posterior part of the maxilla, but were higher in participants with loss of teeth in the anterior part of the maxilla and highest in participants with an edentulous maxilla (P = 0.035). People with normal mouth opening had lower percentage of labiodental distortions than people with a reduced mouth opening (P = 0.05). The proportion of participants with inadequate denture hygiene and distortions of bilabials was 71.4% compared to 10.5% for participants with adequate denture hygiene (P = 0.005). Conclusion: Dentists must consider the impact of a denture on speech, but also should be aware of other oral health factors that influence the speech and quality of life of elders

SYNTHESIS AND CHARACTERIZATION OF TOLUENE SULFONIC ACID (TSA)-DOPED POLYPYRROLE NANOPARTICLES: EFFECTS OF DOPANT CONCENTRATIONS

Nanoparticles of the conducting polymer polypyrrole in toluene sulfonic acid (PPy/TSA) were synthesized and characterized. The polymerization was process carried out in situ using ammonium persulfate (APS) as an oxidant. The particles were synthesized by varying the dopant concentration of para-toluene sulfonic acid over five sulphonic acid concentrations. The main objective of this study was to examine the effect of TSA dopant concentrations on the properties of polypyrrole nanoparticles. Understanding nature and characteristics of polypyrrole/TSA nanoparticles are important in determining whether the nanoparticles have the potential to be a component in the manufacture of fuel cells. The conducting polymer particles synthesized in this study were characterized using a particle analyzer, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), spectroscopy UV-visible (UV-vis), thermogravimetric analysis (TGA) and electrical conductivity measurement. XRD shows that the particles generated possessed an amorphous structure, as also indicated by SEM images revealing the formation of aggregated and granular composite particles. Furthermore, the FTIR peak between 1273 and 1283cm-1 indicated that sulfonic acids (SO3-) groups were present in the structure of PPy. The size of the PPy/TSA nanoparticles was determined to be approximately 24-51 nm, and their conductivity measured to be 1.3 x 10-1 S/cm

SYNTHESIS AND CHARACTERIZATION OF TOLUENE SULFONIC ACID (TSA)-DOPED POLYPYRROLE NANOPARTICLES: EFFECTS OF DOPANT CONCENTRATIONS

Nanoparticles of the conducting polymer polypyrrole in toluene sulfonic acid (PPy/TSA) were synthesized and characterized. The polymerization was process carried out in situ using ammonium persulfate (APS) as an oxidant. The particles were synthesized by varying the dopant concentration of para-toluene sulfonic acid over five sulphonic acid concentrations. The main objective of this study was to examine the effect of TSA dopant concentrations on the properties of polypyrrole nanoparticles. Understanding nature and characteristics of polypyrrole/TSA nanoparticles are important in determining whether the nanoparticles have the potential to be a component in the manufacture of fuel cells. The conducting polymer particles synthesized in this study were characterized using a particle analyzer, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), spectroscopy UV-visible (UV-vis), thermogravimetric analysis (TGA) and electrical conductivity measurement. XRD shows that the particles generated possessed an amorphous structure, as also indicated by SEM images revealing the formation of aggregated and granular composite particles. Furthermore, the FTIR peak between 1273 and 1283cm-1 indicated that sulfonic acids (SO3-) groups were present in the structure of PPy. The size of the PPy/TSA nanoparticles was determined to be approximately 24-51 nm, and their conductivity measured to be 1.3 x 10-1 S/cm

The COVID-19 pandemic as a window of opportunity for more sustainable and circular supply chains

The COVID-19 pandemic is a microcosm for future challenges and crises. The greatest of these challenges is the climate crisis and the potential collapse of our Earth system. However, crises may also provide opportunities to transition to more sustainable futures. In our study, we qualitatively analyze statements of a heterogeneous group of 46 experts from academia, industry, government, and organized civil society to explore inasmuch experts perceived the pandemic as a window of opportunity for more sustainable supply chains (SCs) and what they consider opportunities, challenges, and necessary actions for more sustainable circular SCs. Our study contributes to current and future studies on the opportunities in times of crisis and the actions needed to overcome SCs vulnerabilities, thereby increasing the resiliency, circularity, and sustainability of SCs

Architecture of the biofilm-associated archaic Chaperone-Usher pilus CupE from Pseudomonas aeruginosa

Chaperone-Usher Pathway (CUP) pili are major adhesins in Gram-negative bacteria, mediating bacterial adherence to biotic and abiotic surfaces. While classical CUP pili have been extensively characterized, little is known about so-called archaic CUP pili, which are phylogenetically widespread and promote biofilm formation by several human pathogens. In this study, we present the electron cryomicroscopy structure of the archaic CupE pilus from the opportunistic human pathogen Pseudomonas aeruginosa. We show that CupE1 subunits within the pilus are arranged in a zigzag architecture, containing an N-terminal donor β-strand extending from each subunit into the next, where it is anchored by hydrophobic interactions, with comparatively weaker interactions at the rest of the inter-subunit interface. Imaging CupE pili on the surface of P. aeruginosa cells using electron cryotomography shows that CupE pili adopt variable curvatures in response to their environment, which might facilitate their role in promoting cellular attachment. Finally, bioinformatic analysis shows the widespread abundance of cupE genes in isolates of P. aeruginosa and the co-occurrence of cupE with other cup clusters, suggesting interdependence of cup pili in regulating bacterial adherence within biofilms. Taken together, our study provides insights into the architecture of archaic CUP pili, providing a structural basis for understanding their role in promoting cellular adhesion and biofilm formation in P. aeruginosa