Properties of ion-cyclotron waves in the open solar corona

Remote observations of coronal holes have strongly implicated the resonant interactions of ion-cyclotron waves with ions as a principal mechanism for plasma heating and acceleration of the fast solar wind. In order to study these waves, a WKB (Wentzel-Kramers-Brillouin) linear perturbation analysis is used in the work frame of the collisionless multi-fluid model where we consider in addition to the protons a second ion component made of alpha particles. We consider a non-uniform background plasma describing a funnel region in the open coronal holes and we use the ray tracing Hamiltonian type equations to compute the ray path of the waves and the spatial variation of their properties.Comment: 16 pages, 6 figure

Ray tracing of ion-cyclotron waves in a coronal funnel

Remote observations of coronal holes have strongly implicated the kinetic interactions of ion-cyclotron waves with ions as a principal mechanism for plasma heating and acceleration of the fast solar wind. In order to study these waves, a linear perturbation analysis is used in the work frame of the collisionless multi-fluid model. We consider a non-uniform background plasma describing a funnel region and use the ray tracing equations to compute the ray path of the waves as well as the spatial variation of their properties.Comment: 4 pages, 3 figures Modern Solar Facilities, Advanced Solar Science, Universitatsverlag Goettingen 200

Coronal ion-cyclotron beam instabilities within the multi-fluid description

Spectroscopic observations and theoretical models suggest resonant wave-particle interactions, involving high-frequency ion-cyclotron waves, as the principal mechanism for heating and accelerating ions in the open coronal holes. However, the mechanism responsible for the generation of the ion-cyclotron waves remains unclear. One possible scenario is that ion beams originating from small-scale reconnection events can drive micro-instabilities that constitute a possible source for the excitation of ion-cyclotron waves. In order to study ion beam-driven electromagnetic instabilities, the multi-fluid model in the low-beta coronal plasma is used. While neglecting the electron inertia this model allows one to take into account ion-cyclotron wave effects that are absent from the one-fluid MHD model. Realistic models of density and temperature as well as a 2-D analytical magnetic field model are used to define the background plasma in the open-field funnel region of a polar coronal hole. Considering the WKB approximation, a Fourier plane-wave linear mode analysis is employed in order to derive the dispersion relation. Ray-tracing theory is used to compute the ray path of the unstable wave as well as the evolution of the growth rate of the wave while propagating in the coronal funnel. We demonstrate that, in typical coronal holes conditions and assuming realistic values of the beam velocity, the free energy provided by the ion beam propagating parallel the ambient field can drive micro-instabilities through resonant ion-cyclotron excitation.Comment: 8 pages, 6 figures, submitted to A&

Antioxidant and anti-inflammatory activities of different extracts from aerial parts of Zilla spinosa (L.) Prantl

Zilla spinosa L. is a medicinal plant widely used in traditional Algerian phytotherapy against urinary lithiasis. The present study aims to evaluate the antioxidant and anti-inflammatory effects of different extracts from the aerial part of this plant. The antioxidant activity of the extracts was examined by two different methods, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and cupric reducing antioxidant capacity (CUPRAC). The anti-inflammatory activity of Z. spinosa was determined by the protein denaturation method. The qualitative phytochemical screening shows the presence of the majority of secondary metabolites in the aerial parts except anthraquinones and steroids, on the other hand, the root is characterized by the absence of several metabolites except tannins and coumarins.The ethyl acetate fraction displayed the highest antioxidant capacity (IC50 value: 10.47±0.18 μg/mL in DPPH assay, and A0.50 value: 40.89 ± 0.86 μg/mL in CUPRAC). The percentage of inhibition of BSA denaturation (0.2%) is proportional to the concentration of the different plant extracts, where the highest percentage was recorded in the concentrations of ethyl acetate 500; 250 μg/mL compared to Diclofenac (75 mg/3 mL), in contrast to the aqueous extract which gave non-significant results compared to the standards (p≥5℅). In comparison to the standards used in this study, the ethyl acetate extract demonstrated better DPPH inhibitory activity, while all organic extracts demonstrated lower CUPRAC inhibitory activity but higher anti-inflammatory activity

Mutual interaction of pyrolysis operating conditions and surface morphology for the electrochemical performance of biochar-modified screen-printed electrodes

The transition towards a low-emission economy requires advanced carbon-based materials for multiple applications. This study aimed to correlate the temperature of intermediate pyrolysis with surface morphology and the electrochemical performances of biochar from hazelnut shells (HZS) and spent coffee grounds (SCG), obtained as by-products in bio-oil production. For this process, the biochar from HZS and SCG were produced using a labscale screw-type reactor designed in-house and operated in a semi-continuous regime, under two pyrolysis temperatures (450 degrees C and 550 degrees C) and thermal post-treatment (TT) durations of 10 and 60 minutes, respectively. Physical-chemical characterization through Scanning Electron Microscopy (SEM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) revealed distinct structural and electrochemical differences, unrevealing the fundamental importance of the feedstock selection. SEM analysis highlighted a more homogenous and open structure of HZS than SCG-based biochars. Electrochemical testing of biochar-modified screen-printed electrodes (BC-SPEs) demonstrated enhanced electron-transfer efficiency and diffusivity for HZS produced at 550 degrees C, with the HZS_550 variant yielding a 1.5-fold increase in the heterogeneous electron transfer rate constant (k0) and a 2-fold increase in diffusion coefficient (D0) compared to SCG-SPEs. Notably, HZS_550-SPEs showed enhanced sensitivity for both reversible and non-reversible redox probes, achieving a limit of detection (LOD) in the micromolar (mu M) range, halving the LOD of unmodified SPEs. These findings underscore that biochar's electron-transfer efficiency and texture are key factors driving its sensing performance. Crucially, these properties are governed by the formation of graphite-like sheet structures (GSSs), along with crystallinity and aromaticity, which develop from the condensation of amorphous carbon sheets during primary pyrolysis and are largely unaffected by TT

Effects of Bariatric Surgery on COVID-19: a Multicentric Study from a High Incidence Area

Introduction: The favorable effects of bariatric surgery (BS) on overall pulmonary function and obesity-related comorbidities could influence SARS-CoV-2 clinical expression. This has been investigated comparing COVID-19 incidence and clinical course between a cohort of patients submitted to BS and a cohort of candidates for BS during the spring outbreak in Italy. Materials and Methods: From April to August 2020, 594 patients from 6 major bariatric centers in Emilia-Romagna were administered an 87-item telephonic questionnaire. Demographics, COVID-19 incidence, suggestive symptoms, and clinical outcome parameters of operated patients and candidates to BS were compared. The incidence of symptomatic COVID-19 was assessed including the clinical definition of probable case, according to World Health Organization criteria. Results: Three hundred fifty-three operated patients (Op) and 169 candidates for BS (C) were finally included in the statistical analysis. While COVID-19 incidence confirmed by laboratory tests was similar in the two groups (5.7% vs 5.9%), lower incidence of most of COVID-19-related symptoms, such as anosmia (p: 0.046), dysgeusia (p: 0.049), fever with rapid onset (p: 0.046) were recorded among Op patients, resulting in a lower rate of probable cases (14.4% vs 23.7%; p: 0.009). Hospitalization was more frequent in C patients (2.4% vs 0.3%, p: 0.02). One death in each group was reported (0.3% vs 0.6%). Previous pneumonia and malignancies resulted to be associated with symptomatic COVID-19 at univariate and multivariate analysis. Conclusion: Patients submitted to BS seem to develop less severe SARS-CoV-2 infection than subjects suffering from obesity

Synthesis optimization of carbon-supported ZrO2 nanoparticles from different organometallic precursors

We report here the synthesis of carbon-supported ZrO2 nanoparticles from zirconium oxyphthalocyanine (ZrOPc) and acetylacetonate [Zr(acac)4]. Using thermogravimetric analysis (TGA) coupled with mass spectrometry (MS), we could investigate the thermal decomposition behavior of the chosen precursors. According to those results, we chose the heat treatment temperatures (THT) using partial oxidizing (PO) and reducing (RED) atmosphere. By X-ray diffraction we detected structure and size of the nanoparticles; the size was further confirmed by transmission electron microscopy. ZrO2 formation happens at lower temperature with Zr(acac)4 than with ZrOPc, due to the lower thermal stability and a higher oxygen amount in Zr(acac)4. Using ZrOPc at THT C900 °C, PO conditions facilitate the crystallite growth and formation of distinct tetragonal ZrO2, while with Zr(acac)4 a distinct tetragonal ZrO2 phase is observed already at THT C750 °C in both RED and PO conditions. Tuning of ZrO2 nanocrystallite size from 5 to 9 nm by varying the precursor loading is also demonstrated. The chemical state of zirconium was analyzed by X-ray photoelectron spectroscopy, which confirms ZrO2 formation from different synthesis routes

A Functional Proteomic Method for Biomarker Discovery

The sequencing of the human genome holds out the hope for personalized medicine, but it is clear that analysis of DNA or RNA content alone is not sufficient to understand most disease processes. Proteomic strategies that allow unbiased identification of proteins and their post-transcriptional and -translation modifications are an essential complement to genomic strategies. However, the enormity of the proteome and limitations in proteomic methods make it difficult to determine the targets that are particularly relevant to human disease. Methods are therefore needed that allow rational identification of targets based on function and relevance to disease. Screening methodologies such as phage display, SELEX, and small-molecule combinatorial chemistry have been widely used to discover specific ligands for cells or tissues of interest, such as tumors. Those ligands can be used in turn as affinity probes to identify their cognate molecular targets when they are not known in advance. Here we report an easy, robust and generally applicable approach in which phage particles bearing cell- or tissue-specific peptides serve directly as the affinity probes for their molecular targets. For proof of principle, the method successfully identified molecular binding partners, three of them novel, for 15 peptides specific for pancreatic cancer

Insights into Hox Protein Function from a Large Scale Combinatorial Analysis of Protein Domains

Protein function is encoded within protein sequence and protein domains. However, how protein domains cooperate within a protein to modulate overall activity and how this impacts functional diversification at the molecular and organism levels remains largely unaddressed. Focusing on three domains of the central class Drosophila Hox transcription factor AbdominalA (AbdA), we used combinatorial domain mutations and most known AbdA developmental functions as biological readouts to investigate how protein domains collectively shape protein activity. The results uncover redundancy, interactivity, and multifunctionality of protein domains as salient features underlying overall AbdA protein activity, providing means to apprehend functional diversity and accounting for the robustness of Hox-controlled developmental programs. Importantly, the results highlight context-dependency in protein domain usage and interaction, allowing major modifications in domains to be tolerated without general functional loss. The non-pleoitropic effect of domain mutation suggests that protein modification may contribute more broadly to molecular changes underlying morphological diversification during evolution, so far thought to rely largely on modification in gene cis-regulatory sequences