Line broadening of confined CO gas: from molecule-wall to molecule-molecule collisions with pressure.

The infrared absorption in the fundamental band of CO gas confined in porous silica xerogel has been recorded at room temperature for pressures between about 5 and 920 hPa using a high resolution Fourier transform spectrometer. The widths of individual lines are determined from fits of measured spectra and compared with ab initio predictions obtained from requantized classical molecular dynamics simulations. Good agreement is obtained from the low pressure regime where the line shapes are governed by molecule-wall collisions to high pressures where the influence of molecule-molecule interactions dominates. These results, together with those obtained with a simple analytical model, indicate that both mechanisms contribute in a practically additive way to the observed linewidths. They also confirm that a single collision of a molecule with a wall changes its rotational state. These results are of interest for the determination of some characteristics of the opened porosity of porous materials through optical soundings.

Implication of IL-12A, IL-12B, IL-6, and TNF single-nucleotide polymorphisms in severity and susceptibility to COVID-19.

BACKGROUND: The Coronavirus Disease 2019 (COVID-19) pandemic has led to significant global morbidity and mortality. Understanding the genetic factors that influence disease outcomes can provide critical insights into pathogenesis and potential therapeutic targets. OBJECTIVE: This study aimed to investigate the potential correlation between single nucleotide polymorphisms (SNPs) in Interleukin 12 Subunit Alpha (IL-12A), Interleukin 12 Subunit Beta (IL-12B), Interleukin 6 (IL-6), and Tumor Necrosis Factor (TNF) genes and the severity as well as susceptibility to COVID-19 among Moroccan patients. PATIENTS AND METHODS: Next-Generation sequencing (NGS) was conducted on 325 Moroccan participants, 207 patients with PCR-confirmed Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection and 118 controls. Among these patients, 51% presented moderate to severe symptoms requiring hospitalization, while 49% were asymptomatic or experienced mild symptoms and did not require hospitalization. Statistical analysis was performed using codominant, dominant, and recessive logistic regression models to assess correlations with the severity and susceptibility to COVID-19 infection. RESULTS: No association was found between SNPs of IL-12A, IL-12B, IL-6 or TNF and COVID-19 severity and susceptibility. However, our results unveiled a noteworthy association with IL-6 rs2069840, which exhibited a negative correlation (OR = 0.21, 95% CI = 0.07-0.69, p = .006), suggesting a protective effect against SARS-CoV-2 infection. CONCLUSION: Polymorphisms in IL-12A, IL-12B, IL-6, and TNF genes are not correlated to the severity and susceptibility of COVID-19.

TYK2, IFITM3, IFNAR2 and OAS3 single-nucleotide polymorphisms among severe COVID-19 ICU patients in Morocco.

OBJECTIVES: This study aimed to explore the potential correlation between specific single nucleotide polymorphisms (TYK2, IFITM3, IFNAR2, and OAS3 variants) and the severity of COVID-19 in Moroccan patients. METHODS: A genetic analysis was conducted on 109 patients with PCR-confirmed SARS-CoV-2 infection in Morocco. Among these patients, 46% were hospitalized in the intensive care unit, while 59% were not hospitalized. Importantly, all patients lacked known risk factors associated with COVID-19 severity. Genotyping was performed to identify variations in TYK2 rs74956615, IFITM3 rs12252, IFNAR2 rs2236757, and OAS3 rs10735079. Statistical analysis was applied using codominant, dominant and recessive logistic regression models to assess correlations with COVID-19 severity. RESULTS: Our findings revealed no significant correlation between TYK2 rs74956615, IFITM3 rs12252, IFNAR2 rs2236757, and OAS3 rs10735079 with COVID-19 severity in Moroccan patients, as indicated in logistic regression models (p > .05). Interestingly, these results may offer insights into the mitigated impact of the COVID-19 pandemic and the reduced severity observed in SARS-CoV-2 infected patients in Morocco. Age, however, exhibited a significant correlation with severity (p < .001), with a trend towards increased likelihood of ICU admission with advancing age. Additionally, In the severe group, a higher proportion of patients were females (54%), indicating a statistically significant correlation with disease severity (p = .04). Nevertheless, female ICU patients aged above 60 years accounted for 37%, compared to 17% for males. CONCLUSION: This study underscores the absence of a genetic association between the selected polymorphisms and COVID-19 severity in Moroccan patients. Advanced age emerges as the primary factor influencing the severity of COVID-19 patients without comorbidities. We recommend setting the threshold for advanced age at 60 years as a risk factor for severe forms of COVID-19.

Linear and nonlinear optical properties of gold nanoparticle-doped photonic crystal fiber.

We report on the production of air/silica photonic crystal fiber doped with gold nanoparticles. The stack-and-draw technique was used to combine a gold nanoparticles-doped silica core rod synthesized by the sol-gel route with capillaries drawn from commercially available silica tubes. The presence of nanoparticles in the core region was confirmed at the different steps of the process down to the fiber geometry, even after multiple drawings at ~2000 °C. Optical properties of the fiber were investigated and put in evidence the impact of gold nanoparticles on both linear and nonlinear transmission.

Optical properties of Bismuth-doped silica core photonic crystal fiber.

Optical properties of a Bismuth-doped pure silica sol-gel core photonic crystal fiber (PCF) were investigated. We report on the absorption, CW luminescence and time resolved luminescence spectra at different excitation wavelengths at room temperature. Complex structure of the energy levels of Bismuth-connected centers in pure silica glass is put in evidence.

Optical spectroscopy of bismuth-doped pure silica fiber preform.

We report on the optical spectroscopy of monolithic fiber preform prepared from nanoporous bismuth-doped silica glass. The experiments reveal the existence of at least two different types of active centers and clearly demonstrate that the presence in the glass matrix of other dopant is not necessary to obtain the near-IR photoluminescence connected to Bismuth.

Laser-induced direct space-selective precipitation of CdS nanoparticles embedded in a transparent silica xerogel.

A simple method, suitable for direct space-selective precipitation of semiconducting nanoparticles inside a transparent silica xerogel, is presented. The porous silica monoliths, prepared by the sol-gel method, are first loaded with specific CdS precursors. Then, the samples can be irradiated using either a femtosecond laser to generate the nanoparticles inside the deep volume of the silica matrix or a continuous visible laser to yield a nanocrystal growth under the surface. The resulting CdS nanoparticles are characterized using absorption and Raman spectroscopies, x-ray diffraction analysis and transmission electron microscopy.

Novel Gd3+-doped silica-based optical fiber material for dosimetry in proton therapy.

Optical fibers hold promise for accurate dosimetry in small field proton therapy due to their superior spatial resolution and the lack of significant Cerenkov contamination in proton beams. One known drawback for most scintillation detectors is signal quenching in areas of high linear energy transfer, as is the case in the Bragg peak region of a proton beam. In this study, we investigated the potential of innovative optical fiber bulk materials using the sol-gel technique for dosimetry in proton therapy. This type of glass is made of amorphous silica (SiO[Formula: see text]) and is doped with Gd[Formula: see text] ions and possesses very interesting light emission properties with a luminescence band around 314 nm when exposed to protons. The fibers were manufactured at the University of Lille and tested at the TRIUMF Proton Therapy facility with 8.2-62.9 MeV protons and 2-6 nA of extracted beam current. Dose-rate dependence and quenching were measured and compared to other silica-based fibers also made by sol-gel techniques and doped with Ce[Formula: see text] and Cu[Formula: see text]. The three fibers present strong luminescence in the UV (Gd) or visible (Cu,Ce) under irradiation, with the emission intensities related directly to the proton flux. In addition, the 0.5 mm diameter Gd[Formula: see text]-doped fiber shows superior resolution of the Bragg peak, indicating significantly reduced quenching in comparison to the Ce[Formula: see text] and Cu[Formula: see text] fibers with a Birks' constant, k[Formula: see text], of (0.0162 [Formula: see text] 0.0003) cm/MeV in comparison to (0.0333 [Formula: see text] 0.0006) cm/MeV and (0.0352 [Formula: see text] 0.0003) cm/MeV, respectively. To our knowledge, this is the first report of such an interesting k[Formula: see text] for a silica-based optical fiber material, showing clearly that this fiber presents lower quenching than common plastic scintillators. This result demonstrates the high potential of this inorganic fiber material for proton therapy dosimetry.