Are Investors’ Attention and Uncertainty Aversion the Risk Factors for Stock Markets? International Evidence from the COVID-19 Crisis

In this paper, we examine the impact of investors’ attention to COVID-19 on stock market returns and the moderating effect of national culture on this relationship. Using daily data from 34 countries over the period 23 January to 12 June 2020, and measuring investors’ attention with the Google search volume (GSV) of the word “coronavirus” for each country, we find that investors’ enhanced attention to the COVID-19 pandemic results in negative stock market returns. Further, measuring the national culture with the uncertainty avoidance index (the aspect of national culture which measures the cross-country differences in decision-making under stress and ambiguity), we find that the negative impact of investors’ attention on stock market returns is stronger in countries where investors possess higher uncertainty avoidance cultural values. Our findings imply that uncertainty avoidance cultural values of investors promote financial market instability amid the crisis

Investigation of Toxic Metals in the Tobacco of Pakistani Cigarettes Using Proton-Induced X-Ray Emission

A particle-induced X-ray emission (PIXE) study has been carried out to find out whether available local and imported cigarette brands in Pakistan have elevated concentration of metals or not. The results are compared within the brands examined in this study and with the results of related studies in literature. A sum of 19 different cigarette brands was purchased randomly from different Pakistani markets which included local and imported brands. The concentration of elements like Cd, Pb, Zn, Fe, Mn, Ni, Cu, and Co was investigated. Results showed that different cigarette brands have different metal contents. The mean concentration of the heavy metals is Cd—4.92 μg/g, Co—0.12 μg/g, Cu—0.97 μg/g, Ni—0.13 μg/g, Pb—1.02 μg/g, and Zn—12.91 μg/g per dry weight. Compared with the reported results of other international studies, Pakistani cigarettes are observed to have lower heavy metal contents except for cadmium which was higher. This study will provide adequate data for all concerned departments. This study will also create awareness among people about the toxicity of metals present in tobacco of cigarettes

Relative contribution of nitrogen absorption, remobilization, and partitioning to the ear during grain filling in chinese winter wheat

Knowledge of the function of the ear as a key organ in the uptake, remobilization and partitioning of nitrogen is essential for understanding its contribution to grain filling and thus guiding future breeding strategies. In this work, four Chinese winter wheat genotypes were grown on a 15N-enriched nutrient solution. N absorption and further remobilization to the flag leaf, the ear and the mature grains were calculated via the 15N atom%excess. The results indicated that the high yields of the Chinese wheat genotype were determined by higher grain numbers per ear, with greater plant height and a larger ear size, while the thousand-grain weight did not affect grain yield. In the mature grains, 66.7% of total N was remobilized from the pre-anthesis accumulation in the biomass, while the remaining 33.3% was derived from the N taken up during post-anthesis. From anthesis to 2 weeks after the anthesis stage, the flag leaf remobilized 3.67mg of N outwards and the ear remobilized 3.87mg of N inwards from the pre-anthesis accumulation in each plant. The positive correlation between ear Nrem and grain Nrem indicated that the ear was an important organ for providing N to the grain, whereas the remobilized N stream from the leaves was not correlated with grain Nrem, thus indicating that flag leaf N was not translocated directly to the grain. The grain Nrem was negatively correlated with the ear N concentration throughout grain filling, which suggested that higher-yielding genotypes had better sink activity in the ear, while Rubisco played a critical role in N deposition. Therefore, to improve yield potential in wheat, the N accumulation in the ear and the subsequent remobilization of that stored N to the grains should be considered. N accumulation and remobilization in the ear may at least be valuable for Chinese breeding programs that aim at optimizing the sink/source balance to improve grain filling

Alterations in the magnetic and electrodynamic properties of hard-soft Sr0.5Ba0.5Eu0.01Fe12O19/NixCuyZnwFe2O4 nanocomposites

Hard/soft (H/S) Sr0.5Ba0.5Eu0.01Fe12O19/NixCuyZnwFe2O4 nanocomposites (NCs) were produced via a one-pot sol–gel auto-combustion procedure. Phase and surface analyses were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HR-TEM). Magnetization measurements for H/S NCs with different x, y, and w ratios were investigated at two different temperatures (300 and 10 K). The M−H curves were not smooth for the different H/S NCs, revealing that the exchange interaction was incomplete. The derivative of the magnetization (dM/dH versus H) exhibited two separate peaks, confirming the non-coupled H/S mixtures. Maximum saturation magnetization (Ms) values of 93.9 and 63.1 emu/g were obtained at 10 and 300 K, respectively, for the H/S Sr0.5Ba0.5Eu0.01Fe11.99O19/Ni0.3Cu0.3Zn0.4Fe2O4 NC, which contained the highest content of Zn and the same contents of Ni and Cu within the soft magnetic phase. The calculated squareness ratios (SQR = Mr/Ms) were less than 0.5, indicating incomplete exchange coupling. The coercive field (Hc) of the produced NCs reached a maximum value of approximately 2485 Oe at 300 K and 2331 Oe at 10 K with a decrease in the Ms values to 56.9 emu/g at 300 K and 78.5 emu/g at 10 K for the H/S Sr0.5Ba0.5Eu0.01Fe11.99O19/Ni0.8Cu0.1Zn0.1Fe2O4 NC, which contained lower fractions of Zn and Cu and the highest fraction of Ni. The reflection/transmission-based waveguide approach was employed to investigate the electrodynamic properties of the H/S NC samples within a frequency band of 7–18 GHz. The reflection and transmission coefficients (S11/S21) were measured using a vector network analyzer (VNA) for the sample placed inside a waveguide. The frequency dispersions of the magnetic permeability and electric permittivity were calculated. © 2021 The Author(s)2020-164-IRMC; King Fahd University of Petroleum and Minerals, KFUPM; Russian Science Foundation, RSF: 21-79-10115This study was supported by the Deanship of Scientific Research of Imam Abdulrahman Bin Faisal University (Dammam, Saudi Arabia) through Grant No. 2020-164-IRMC . The authors also acknowledge support from the Center for Communication Systems and Sensing at KFUPM . Electromagnetic measurements and analysis were partially supported by the Russian Science Foundation (Agreement No. 21-79-10115)

Functional sr0.5ba0.5sm0.02fe11.98o4/x(ni0.8zn0.2fe2o4) hard-soft ferrite nanocomposites: Structure, magnetic and microwave properties

This paper reports the correlation between the composition of the functional Sr0.5Ba0.5Sm0.02Fe11.98O19/x(Ni0.8Zn0.2Fe2O4) hard-soft nanocomposites (SrBaSmFe/x(NiZnFe) NCs), where 0.0 ≤ x ≤ 3.0, and their structural features, magnetic, and microwave properties. SrBaSmFe/x(NiZnFe) hard/soft ferrite NCs are produced using the one-pot citrate combustion method. According to the XRD analysis, all samples showed the co-existence of both SrBaSmFe and NiZnFe phases in different ratios. Magnetic properties are measured in a wide range of magnetic fields and temperatures (10 and 300 K) and correlated well with the composition of the investigated samples. The microwave properties (frequency dispersions of the magnetic permeability, and electrical permittivity) are discussed by using the co-axial method in the frequency range of 0.7-18 GHz. Non-linear dependences of the main microwave features were observed with varying of composition. The microwave behavior correlated well with the composite theory. These results could be used in practice for developing antenna materials. © 2020 by the authors.This work was financially supported by the Deanship for Scientific Research (Project application No. 2020-164-IRMC) of Imam Abdulrahman Bin Faisal University (IAU—Saudi Arabia). The work was partially supported by the Russian Science Foundation (Agreement No. 19-72-10071 from 06 August 2019)

Fabrication of exchange coupled hard/soft magnetic nanocomposites: Correlation between composition, magnetic, optical and microwave properties

This paper studied the exchange coupling performance beside structural and microwave properties of SrFe12O19 (SFO) and x(CoTm0.01Tb0.01Fe1.98O4) (CoTmTb) (x ≤ 3.0) hard/soft ferrites nanocomposites (NCs). The structure and morphology of NCs were investigated by XRD, SEM, TEM and HR-TEM. Diffuse reflectance spectroscopic (DRS) measurements were applied on hexagonal ferrite, on spinel ferrite nanoparticles and on hard/soft NCs to specify the optical properties. Estimated Eg data are in a range between 1.32 and 1.79 eV. The magnetic properties were also inspected via measurements of magnetization (M) against magnetic field (H) at 300 K (RT) and 10 K (LT). The measurements performed at RT along with the plots of dM/dH versus H indicated that the NCs display good magnetic properties (exchange coupling behavior). The magnetic parameters such as (Ms, Mr, and Hc) show an enhancement in their values with an increasing the soft content at RT. Similarly, the maximum energy product (BH)max rises and reaches its max value for SFO/3(CoTmTb) NCs. Microwave properties of the SFO/x(CoTmTb) NCs were measured in the frequency range 33–50 GHz. From measured S11 and S21 parameters the main electrodynamic characteristics – permittivity and permeability (real and imaginary parts) were computed. © 2021 The Author(s)This work was financially supported by the Deanship for Scientific Research (Project application No. 2020-164-IRMC) of Imam Abdulrahman Bin Faisal University (IAU ? Saudi Arabia). Microwave characterization was partially supported by the Russian Science Foundation (Agreement No. 19-72-10071 from 06 Aug. 2019)

Guillain-Barré syndrome in pregnancy: An unusual case

Guillain-Barré syndrome (GBS) is rare in pregnancy with an estimated incidence between 1.2 and 1.9 cases per 100,000 people annually, and it carries a high maternal risk. We report a 29-year-old primigravida who had pain and progressive heaviness of both lower limbs in her third trimester of pregnancy. The attending gynecologist ascribed these symptoms to ongoing pregnancy. The intrapartum period (lower segment caesarian section) passed uneventfully. On third postpartum day, the patient developed weakness of all the four limbs. A detailed history and physical examination pointed toward GBS although there was no antecedent infective episode. Subsequent nerve conduction velocity studies and cerebrospinal fluid analysis confirmed GBS. All other investigations including electrolytes were normal. The patient improved without the introduction of immunomodulating therapy

Structural, optical and magnetic properties of Tb3+ substituted Co nanoferrites prepared via sonochemical approach

This paper emphasizes the structure, morphology, optical, and magnetic properties of sonochemically prepared terbium-substituted cobalt ferrite nanoparticles, CoTbxFe2-xO4 (0.00 ? x ? 0.10). The formation of cubic spinel nanosized ferrite structure was confirmed by X-ray diffraction (XRD), Field-emission scanning electron microscopy (FE-SEM), and Fourier-transform infrared (FT-IR) spectroscopy. The crystallites sizes were found in the range of 11–14 nm. Ultraviolet–visible percentage diffuse reflectance investigations were performed on pristine and Tb3+-doped cobalt spinel ferrite CoFe2O4 nanoparticles. The direct energy band gap (Eg) values were determined by applying the Kubelka–Munk theory and Tauc plots were found to be in a narrow band range of 1.37–1.44 eV. Analyses of magnetization versus the magnetic field (M(H)) were performed. The magnetic parameters, including the saturation magnetization (Ms), squareness ratio (SQR = Mr/Ms), magnetic moment (nB), remanence (Mr), and coercivity (Hc) were evaluated. The M(H) curves exhibited a soft ferrimagnetic nature. It was demonstrated that the Tb3+ substitutions strongly influenced the magnetization data. Indeed, the Ms, Mr, Hc, and nB values decreased with increasing Tb3+ substitution. © 2019 Elsevier Ltd and Techna Group S.r.l.Deanship of Scientific Research, King Saud University: 2018-209-IRMC, 2017-576-IRMCThis study was supported by the Deanship of Scientific Research (project applications 2017-576-IRMC and 2018-209-IRMC ) of Imam Abdulrahman Bin Faisal University (Saudi Arabia)