The function of astrocytes and their role in neurological diseases.

Astrocytes have countless links with neurons. Previously, astrocytes were only considered a scaffold of neurons; in fact, astrocytes perform a variety of functions, including providing support for neuronal structures and energy metabolism, offering isolation and protection and influencing the formation, function and elimination of synapses. Because of these functions, astrocytes play an critical role in central nervous system (CNS) diseases. The regulation of the secretiory factors, receptors, channels and pathways of astrocytes can effectively inhibit the occurrence and development of CNS diseases, such as neuromyelitis optica (NMO), multiple sclerosis, Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease. The expression of aquaporin 4 in AS is directly related to NMO and indirectly involved in the clearance of Aß and tau proteins in AD. Connexin 43 has a bidirectional effect on glutamate diffusion at different stages of stroke. Interestingly, astrocytes reduce the occurrence of PD through multiple effects such as secretion of related factors, mitochondrial autophagy and aquaporin 4. Therefore, this review is focused on the structure and function of astrocytes and the correlation between astrocytes and CNS diseases and drug treatment to explore the new functions of astrocytes with the astrocytes as the target. This, in turn, would provide a reference for the development of new drugs to protect neurons and promote the recovery of nerve function.

Extended Lifetime of Respiratory Droplets in a Turbulent Vapor Puff and Its Implications on Airborne Disease Transmission.

To quantify the fate of respiratory droplets under different ambient relative humidities, direct numerical simulations of a typical respiratory event are performed. We found that, because small droplets (with initial diameter of 10 µm) are swept by turbulent eddies in the expelled humid puff, their lifetime gets extended by a factor of more than 30 times as compared to what is suggested by the classical picture by Wells, for 50% relative humidity. With increasing ambient relative humidity the extension of the lifetimes of the small droplets further increases and goes up to around 150 times for 90% relative humidity, implying more than 2 m advection range of the respiratory droplets within 1 sec. Employing Lagrangian statistics, we demonstrate that the turbulent humid respiratory puff engulfs the small droplets, leading to many orders of magnitude increase in their lifetimes, implying that they can be transported much further during the respiratory events than the large ones. Our findings provide the starting points for larger parameter studies and may be instructive for developing strategies on optimizing ventilation and indoor humidity control. Such strategies are key in mitigating the COVID-19 pandemic in the present autumn and upcoming winter.

Enhanced Power Factor and Increased Conductivity of Aluminum Doped Zinc Oxide Thin Films for Thermoelectric Applications.

We report the structural, electrical and thermopower properties of un-doped and Al doped zinc oxide (ZnO) thin films. Al doping was carried out using 25 keV Al+ implantation with 0.1, 1 and 2% Al into ZnO. X-ray diffraction measurements showed that the lattice parameters were larger than the bulk values, which is consistent with the incorporation of Al atoms at interstitials. Al doping increased the electrical conductivity from 100 (Ωcm)-1 in the un-doped ZnO film to 598 (Ωcm)-1 in the 2% Al doped ZnO film. Electron doping by Al resulted in an increase in the carrier concentration and it had an advantageous effect on the mobility where it was highest for 2% doping. The absolute value of the Seebeck coefficient systematically increased for un-doped, 1% and 2% Al doped ZnO films where the room temperature values were -50.8, -60.9 and -66.3 µV/K, respectively. The power factor increased significantly from 2.58 × 10-5 W/mK2 in un-doped ZnO film to 2.63 × 10-4 W/mK2 in 2% Al doped ZnO film. Our results suggest that the ion beam method is a suitable technique to enhance the thermoelectric properties of ZnO.

Puerarin Suppresses Angiotensin II-Induced Cardiac Hypertrophy by Inhibiting NADPH Oxidase Activation and Oxidative Stress-Triggered AP-1 Signaling Pathways.

PURPOSE: To examine the effects of puerarin (Pue) on angiotensin II (AngII)-induced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation and oxidative stress-related signaling pathways in the hypertrophic response of cardiomyocytes. METHODS: Primary cardiomyocytes of neonatal C57BL/6J mice were pretreated with Pue (50, 100 µmol/L) and were then stimulated with AngII 1 µmol/L. NADPH oxidase activity and reactive oxygen species (ROS) levels were measured by lucigenin-enhanced chemiluminescence assay and flow cytometry. Western blotting was used to detect the distribution of the oxidase subunits, extracellular signal-regulated kinase (ERK1/2) and c-jun N-terminal kinase (JNK1/2) activation, and an electrophoretic mobility shift assay (EMSA) was performed to analyze the DNA binding activity of activator protein-1 (AP-1). Adult C57BL/6J mice were infused with AngII and were administered with Pue (100, 200 mg·kg-1·d-1) for 15 d. After the treatment, systolic blood pressure (SBP) and left ventricular wall thickness were examined. The ratios of heart weight to body weight (HW/BW) and left ventricular weight to body weight (LVW/BW) were measured, and heart morphometry was assessed. RESULTS: In vitro, Pue dose-dependently blocked the phosphorylation of ERK1/2 and JNK1/2 and eventually abolished AP-1 binding activity through the inhibition of ROS production. Further studies revealed that AngII treatment resulted in increased NADPH oxidase activity, which was suppressed by Pue via the disruption of Rac1 activation and membrane translocation of oxidase subunits. In vivo, Pue attenuated cardiac hypertrophy, as evaluated by decreased HW/BW, LVW/BW, myocyte surface area, and left ventricular wall thickness. CONCLUSIONS: The anti-hypertrophic mechanism of Pue occurred by blocking Rac1-dependent NADPH oxidase activation and downstream redox-sensitive AP-1 signaling pathways.

Iron(II) spin crossover complexes of tetradentate Schiff-bases: tuning T1/2 by choice of formyl-heterocycle component.

Four new tetradentate Schiff-base ligands were prepared in situ from the 1 : 2 condensation of 1,3-diaminopropane and either 2-thiazolecarboxaldehyde (L2thiazole), 4-thiazolecarboxaldehyde (L4thiazole), 4-oxazolecarboxaldehyde (L4oxazole), or 5-bromopyridine-2-aldehyde (L5Br-pyridine), and complexed with [Fe(NCS)2(pyridine)4] to give four monometallic FeII complexes, [Fe(Lheterocycle)(NCS)2]. Structural characterisation shows the expected octahedral FeII centres in all cases, with Lheterocycle occupying the equatorial plane and the two thiocyanate ligands trans to each other, resulting in an N6 coordination sphere. Solid state magnetic measurements showed that the two complexes with the thiazole-based ligands exhibit the beginning of a spin transition above 300 K, with T1/2 = 350 K for [Fe(L4thiazole)(NCS)2] and 400 K for [Fe(L2thiazole)(NCS)2], whereas the 4-oxazole-based ligand gives [Fe(L4oxazole)(NCS)2] which remains high spin at all measured temperatures (50-400 K). Interestingly, [Fe(L5Br-pyridine)(NCS)2] crystallised as two solvent-free polymorphs: magnetic measurements on samples with both polymorphs present showed a two step SCO with an abrupt transition at T1/2 = 245 K assigned to the transition in polymorph A (as this was also seen in a sample of pure polymorph A), and a gradual transition at T1/2 = 304 K assigned to polymorph B. These findings show that the order of increasing ligand field strength for these heterocycles is 4-oxazole ≪ 5Br-pyridine < 4-thiazole < 2-thiazole.

Laser-induced breakdown spectroscopy-guided synergistic phototherapy: A theranostic platform mediated by a single laser wavelength.

Currently, cancer theranostic studies have only focused on integrating existing medical imaging techniques with therapeutic modalities. Obviously, this strategy is not a real theranostic method, as diagnosis and therapy are based on different principles and require independent operation. Here, a cancer theranostic method was established by laser-induced breakdown spectroscopy (LIBS)-mediated synergistic photothermal/photodynamic therapy, which was activated by a single 1064-nm light for simultaneous tumor localization and treatment. PEGylated cobalt phosphate (CoP@PEG) nanoparticles (NPs) with strong near-infrared (NIR)-II absorbance, high photothermal conversion efficiency and a reactive oxygen species generation effect were fabricated, and they produced excellent antitumor outcomes under 1064-nm excitation, as evidenced by the substantial increase in HepG2 cell death in vitro and complete tumor elimination in vivo. Meanwhile, the diagnostic method of the LIBS imaging system used in the present study also uses 1064-nm light. The LIBS imaging system can provide fast, real-time analysis and imaging of elements and facilitate the localization of the tumor site by monitoring the distribution of CoP@PEG NPs for precise tumor treatment. We postulate that this theranostic platform will promote the development of further theranostic research.

Ironsand (Titanomagnetite-Titanohematite): Chemistry, Magnetic Properties and Direct Applications for Wireless Power Transfer.

Ironsand is an abundant and inexpensive magnetic mineral resource. However, the magnetic properties of unprocessed ironsand are often inadequate for any practical applications. In this work, the applicability of ironsand for use as a component in a soft magnetic composite for large-scale inductive power transfer applications was investigated. After magnetic separation, the chemical, structural and magnetic properties of ironsand sourced from different locations were compared. Differences observed in the DC magnetic properties were consistent with changes in the chemical compositions obtained from X-ray Absorption Near-Edge Spectroscopy (XANES), which suggests varying the titanohematite to titanomagnetite content. Increased content in titanomagnetite and magnetic permeability correlated well with the total Fe content in the materials. The best-performing ironsand with the highest permeability and lowest core losses was used alongside Mn,Zn-Ferrite particles (ranging from ∼100 µm to 2 mm) to fabricate toroid cores with varying magnetic material loading. It was shown that ironsand can be used to replace up to 15 wt.% of the magnetic materials with minimal impact on the composite magnetic performance, thus reducing the cost. Ironsand was also used as a supporting material in a single-rail wireless power transfer system, effectively increasing the power transfer, demonstrating potential applications to reduce flux leakage.

Electrospun, Oriented, Ferromagnetic Ni 1-x Fe x Nanofibers.

Electrospinning has been used to fabricate ferromagnetic Ni0.47Fe0.53 nanofiber mats that were composed of individual, orientated Ni0.47Fe0.53 nanofibers. The key steps were processing a polyvinylpyrrolidone nanofiber template containing ferric nitrate and nickel acetate metal precursors in Ar at 300°C and then 95% Ar: 5% H2 at 600°C. The Ni0.47Fe0.53 fibers were nanostructured and contained Ni0.47Fe0.53 nanocrystals with average diameters of ~14 nm. The Ni0.47Fe0.53 ferromagnetic mats had a high saturation magnetic moment per formula unit that was comparable to those reported in other studies of nanostructured Ni1-x Fe x . There is a small spin-disordered fraction that is typically seen in nanoscale ferromagnets and is likely to be caused by the surface of the nanofibers. There was an additional magnetic contribution that could possibly stem from a small Fe1-z Ni z O phase fraction surrounding the fibers. The coercivity was found to be enhanced when compared with the bulk material.

Modelling the radioluminescence of Sm2+ and Sm3+ in the dosimeter material NaMgF3:Sm.

Photoluminescence (PL) and radioluminescence (RL) measurements were made on NaMgF3:Sm before, during and after exposure to high doses of ionising radiation. Magnetic measurements prior to irradiation showed that approximately 10% of the total Sm concentration was in the divalent state. The RL from Sm3+ was found to increase while the Sm2+ RL decreased with increasing x-ray dose before reaching steady-state values for high doses. This behaviour is opposite to that previously reported for Sm3+ and Sm2+ PL. We show that this apparent discrepancy can be accounted for by a RL model where there is a hole trap, an electron trap, and direct x-ray induced carrier recombination at Sm2+ and Sm3+. Furthermore, a good fit to the dose-dependence of all of the Sm RL emissions can be obtained by assuming that the relevant electron and hole traps are close to Sm3+. Our model accounts for F3-centre production during irradiation that affects some of the Sm3+ RL emissions via reabsorption of the RL by the F3-centres. Thus, the rate of F3-centre production can be conveniently monitored by the RL intensity ratio, I RL(567 nm)/I RL(650 nm). Additionally, the Sm2+ RL emissions may be expressed as [1.94 × I RL(721 nm)] - I RL(695 nm) to determine the real-time dose rate, independent of dose history.

Corrigendum: Electrospun, Oriented, Ferromagnetic Ni 1-x Fe x Nanofibers.

[This corrects the article DOI: 10.3389/fchem.2020.00047.].

Association of an intronic variant of the heme oxygenase-1 gene with hypertension in northern Chinese Han population.

Heme oxygenase was regarded as a regulator of oxidative stress, which was believed to underlie the etiology of hypertension. To assess the effect of its encoded genes (HMOX1 and HMOX2) on hypertension, we designed a case-control study in 503 cases and 490 controls. The results indicated that the rs9607267 of the HMOX1 gene was significantly associated with essential hypertension (EH) and the Hap3(T-C-G) of the HMOX1 gene was also significantly associated with the risk of EH. No association was observed between the HMOX2 gene and EH. The multifactor-dimensionality reduction analyses results did not show any interaction between the HMOX1 and HMOX2 genes underlying the development of hypertension.

Unusual 209Bi NMR quadrupole effects in topological insulator Bi2Se3.

Three-dimensional topological insulators are an important class of modern materials, and a strong spin-orbit coupling is involved in making the bulk electronic states very different from those near the surface. Bi2Se3 is a model compound, and 209Bi NMR is employed here to investigate the bulk properties of the material with focus on the quadrupole splitting. It will be shown that this splitting measures the energy band inversion induced by spin-orbit coupling in quantitative agreement with first-principle calculations. Furthermore, this quadrupole interaction is very unusual as it can show essentially no angular dependence, e.g., even at the magic angle the first-order splitting remains. Therefore, it is proposed that the magnetic field direction is involved in setting the quantization axis for the electrons, and that their life time leads to a new electronically driven relaxation mechanism, in particular for quadrupolar nuclei like 209Bi. While a quantitative understanding of these effects cannot be given, the results implicate that NMR can become a powerful tool for the investigation of such systems.

Layered tungsten oxide-based organic-inorganic hybrid materials: an infrared and Raman study.

Tungsten oxide-organic layered hybrid materials have been studied by infrared and Raman spectroscopy and demonstrate a difference in bonding nature as the length of the interlayer organic "spacer" molecule is increased. Ethylenediamine-tungsten oxide clearly displays a lack of terminal -NH3(+) ammonium groups which appear in hybrids with longer organic molecules, thus indicating that the longer chains are bound by electrostatic interactions as well as or in place of the hydrogen bonding that must be present in the shorter chain ethylenediamine hybrids. The presence of organic molecules between the tungsten oxide layers, compared with the layered tungstic acid H2WO4, shows a decrease in the apical W=O bond strength, as might be expected from the aforementioned electrostatic interaction.

Genome-wide linkage and positional association analyses identify associations of novel AFF3 and NTM genes with triglycerides: the GenSalt study.

We conducted a genome-wide linkage scan and positional association study to identify genes and variants influencing blood lipid levels among participants of the Genetic Epidemiology Network of Salt-Sensitivity (GenSalt) study. The GenSalt study was conducted among 1906 participants from 633 Han Chinese families. Lipids were measured from overnight fasting blood samples using standard methods. Multipoint quantitative trait genome-wide linkage scans were performed on the high-density lipoprotein, low-density lipoprotein, and log-transformed triglyceride phenotypes. Using dense panels of single nucleotide polymorphisms (SNPs), single-marker and gene-based association analyses were conducted to follow-up on promising linkage signals. Additive associations between each SNP and lipid phenotypes were tested using mixed linear regression models. Gene-based analyses were performed by combining P-values from single-marker analyses within each gene using the truncated product method (TPM). Significant associations were assessed for replication among 777 Asian participants of the Multi-ethnic Study of Atherosclerosis (MESA). Bonferroni correction was used to adjust for multiple testing. In the GenSalt study, suggestive linkage signals were identified at 2p11.2‒2q12.1 [maximum multipoint LOD score (MML) = 2.18 at 2q11.2] and 11q24.3‒11q25 (MML = 2.29 at 11q25) for the log-transformed triglyceride phenotype. Follow-up analyses of these two regions revealed gene-based associations of charged multivesicular body protein 3 (CHMP3), ring finger protein 103 (RNF103), AF4/FMR2 family, member 3 (AFF3), and neurotrimin (NTM) with triglycerides (P = 4 × 10(-4), 1.00 × 10(-5), 2.00 × 10(-5), and 1.00 × 10(-7), respectively). Both the AFF3 and NTM triglyceride associations were replicated among MESA study participants (P = 1.00 × 10(-7) and 8.00 × 10(-5), respectively). Furthermore, NTM explained the linkage signal on chromosome 11. In conclusion, we identified novel genes associated with lipid phenotypes in linkage regions on chromosomes 2 and 11.

75As NMR study of overdoped CeFeAsO0.8F0.2.

We report on the results from a (75)As nuclear magnetic resonance (NMR) study of the overdoped iron pnictide superconductor CeFeAsO0.8F0.2. We find two As sites with different shifts at temperatures as high as 100 K, which is above the superconducting transition temperature of 39 K, and hence they cannot be attributed to the effect of vortices in the superconducting state as previously suggested (Ghoshray et al 2009 Phys. Rev. B 79 144512). The much larger spin-lattice relaxation rate compared with that found in other pnictides without magnetic rare earth ions, and the temperature dependence of the (75)As NMR shifts for the two central lines, are consistent with the hyperfine coupling from magnetic Ce to As. The low temperature spectra indicate that there are As ions with two different quadrupole splittings. Our findings appear to be consistent with an electronic phase segregation into regions with two different F dopings or the presence of a correlated spatial charge and spin density variations.