A fast radio burst source at a complex magnetized site in a barred galaxy.

Fast radio bursts (FRBs) are highly dispersed, millisecond-duration radio bursts1-3. Recent observations of a Galactic FRB4-8 suggest that at least some FRBs originate from magnetars, but the origin of cosmological FRBs is still not settled. Here we report the detection of 1,863 bursts in 82 h over 54 days from the repeating source FRB 20201124A (ref. 9). These observations show irregular short-time variation of the Faraday rotation measure (RM), which scrutinizes the density-weighted line-of-sight magnetic field strength, of individual bursts during the first 36 days, followed by a constant RM. We detected circular polarization in more than half of the burst sample, including one burst reaching a high fractional circular polarization of 75%. Oscillations in fractional linear and circular polarizations, as well as polarization angle as a function of wavelength, were detected. All of these features provide evidence for a complicated, dynamically evolving, magnetized immediate environment within about an astronomical unit (AU; Earth-Sun distance) of the source. Our optical observations of its Milky-Way-sized, metal-rich host galaxy10-12 show a barred spiral, with the FRB source residing in a low-stellar-density interarm region at an intermediate galactocentric distance. This environment is inconsistent with a young magnetar engine formed during an extreme explosion of a massive star that resulted in a long gamma-ray burst or superluminous supernova.

Diverse polarization angle swings from a repeating fast radio burst source.

Fast radio bursts (FRBs) are millisecond-duration radio transients1,2 of unknown origin. Two possible mechanisms that could generate extremely coherent emission from FRBs invoke neutron star magnetospheres3-5 or relativistic shocks far from the central energy source6-8. Detailed polarization observations may help us to understand the emission mechanism. However, the available FRB polarization data have been perplexing, because they show a host of polarimetric properties, including either a constant polarization angle during each burst for some repeaters9,10 or variable polarization angles in some other apparently one-off events11,12. Here we report observations of 15 bursts from FRB 180301 and find various polarization angle swings in seven of them. The diversity of the polarization angle features of these bursts is consistent with a magnetospheric origin of the radio emission, and disfavours the radiation models invoking relativistic shocks.

No pulsed radio emission during a bursting phase of a Galactic magnetar.

Fast radio bursts (FRBs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances1-3. It has long been speculated that magnetars are the engine powering repeating bursts from FRB sources4-13, but no convincing evidence has been collected so far14. Recently, the Galactic magnetar SRG 1935+2154 entered an active phase by emitting intense soft γ-ray bursts15. One FRB-like event with two peaks (FRB 200428) and a luminosity slightly lower than the faintest extragalactic FRBs was detected from the source, in association with a soft γ-ray/hard-X-ray flare18-21. Here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-X-ray) data. During the third session, 29 soft-γ-ray repeater (SGR) bursts were detected in γ-ray energies. Throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of SGR bursts, but unfortunately we were not observing when the FRB was detected. The non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of FRB 200428. Our results suggest that FRB-SGR burst associations are rare. FRBs may be highly relativistic and geometrically beamed, or FRB-like events associated with SGR bursts may have narrow spectra and characteristic frequencies outside the observed band. It is also possible that the physical conditions required to achieve coherent radiation in SGR bursts are difficult to satisfy, and that only under extreme conditions could an FRB be associated with an SGR burst.

[Short- and mid-term outcomes of percutaneous balloon mitral valvuloplasty under the guidance of ultrasound].

Objective: To evaluate the safety, short- and mid-term outcomes of percutaneous balloon mitral valvuloplasty (PBMV) guided by the ultrasound. Methods: In this retrospective study, medical data of 15 patients [9 males and 6 females, with an age of (53±13) years] with PBMV under the guidance of ultrasound in Heart Center of Henan Provincial People's Hospital between December 2016 and January 2019 were collected and reviewed. The short-and mid-term outcomes were analyzed. Results: PBMV was successfully performed in all the patients. One patient underwent surgical valve replacement due to severe mitral regurgitation, and the other 14 patients were all followed up successfully. The average follow-up time was (13.8±4.6) months. Comparisons of preoperative and postoperative data showed significant differences in valve area [(1.84±0.43) cm2 vs (0.89±0.24) cm2], left atrial pressure [(11.9±4.5) mmHg (1 mmHg=0.133 kPa) vs (21.9±6.0) mmHg] and mean mitral valve pressure gradient [(10.9±3.2) mmHg vs (20.1±3.6) mmHg](all P<0.01), with no significant differences in mitral regurgitation area (P=0.67). Postoperative follow-up showed that there were no significant differences in mitral valve area, regurgitation area and N-terminal pro-B-type natriuretic peptide (NT-proBNP) between short-and mid-term postoperatively (all P>0.05). There was no secondary operation due to mitral stenosis in 14 patients, and 3 patients with moderate or severe tricuspid regurgitation showed significant improvement, with gradually recovered cardiac function, and there were no deaths in these patients. Conclusion: PBMV guided by the ultrasound is feasible and effective, and exhibits favorable short-and mid-term outcomes.

[Current status of blood lipids in people with hypertension and diabetes in Henan province].

Objective: To investigate the blood lipid levels and prevalence of dyslipidemia in people with hypertension and diabetes in Henan province. Methods: From April 2016 to April 2017, multi-stage cluster sampling was adopted to investigate 71 285 local residents aged between 35 and 75 from 6 districts and counties in Henan province including Zhongmu county of Zhengzhou city, Huojia county of Xinxiang city, Hualong district of Puyang city, Qi county of Hebi city, Xigong district of Luoyang city, and Wugang city of Pingdingshan city. Blood samples were collected. According to the diagnostic criteria of hypertension and diabetes, the study population was divided into control group (n=29 427), hypertension group (n=21 965), diabetes group (n=8 009) and hypertension-diabetes group (n=11 884). Comparisons on blood lipid levels and dyslipidemia between 4 groups were performed. Results: The total cholesterol (TC) level of all subjects was 4.37 (3.78, 5.05) mmol/L. The triglyceride (TG) level was 1.27 (0.97, 1.80) mmol/L, the low-density lipoprotein cholesterol (LDL-C) level was 2.34 (1.88, 2.88) mmol/L and the high-density lipoprotein cholesterol (HDL-C) level was 1.31 (1.08, 1.59) mmol/L. Except for the TC level in women aged 65-75 years and LDL-C levels in women aged 55-64 and 65-75 years, there were significant differences in TC, TG, LDL-C and HDL-C levels between subjects of control group, hypertension group, diabetes group, and hypertension-diabetes group in different age ranges (including 35-44, 45-54, 55-64,and 65-75 years) and genders(all P<0.01).Except for the LDL-C and HDL-C in men aged 35-44 years and LDL-C in women aged 65-75 years, there were significant differences in the dyslipidemia rates of TC, TG, LDL-C and HDL-C between subjects of control group, hypertension group, diabetes group and hypertension-diabetes group in different age ranges and genders(P<0.01 or <0.05). After adjusting for age, gender, smoking, drinking, snoring, region, and body mass index, multivariate logistic regression analysis showed that hypertension (OR=1.221, 95%CI 1.113-1.339, P<0.01), diabetes (OR=1.636, 95%CI 1.461-1.833, P<0.01) and hypertension-diabetes (OR=1.832, 95%CI 1.658-2.023, P<0.01) were independent risk factors for TC abnormality. Hypertension (OR=1.566, 95%CI 1.478-1.659, P<0.01), diabetes (OR=2.182, 95%CI 2.031-2.342, P<0.01) and hypertension-diabetes (OR=2.655, 95%CI 2.492-2.829, P<0.01) were also independent risk factors for TG abnormality. Diabetes (OR=1.510, 95%CI 1.309-1.742, P<0.01) and hypertension-diabetes (OR=1.461, 95%CI 1.285-1.661, P<0.01) were independent risk factors for LDL-C abnormality. Diabetes (OR=1.261, 95%CI 1.180-1.346, P<0.01) and hypertension-diabetes (OR=1.195, 95%CI 1.126-1.268, P<0.01) were independent risk factors for HDL-C abnormality. Conclusion: The prevalence of dyslipidemia in patients with hypertension and diabetes is high in Henan province, so adequate blood lipid education and control should be applied to people with risk factors as soon as possible.

Novel benzimidazole salts for lithium ion battery electrolytes: effects of substituents.

In this paper, we report on our effort to design a novel lithium salt derived from bis(trifluoroborane)benzimidazolide by using density functional theory (DFT) calculations. The effects of different substituents are investigated with respect to ion pair dissociation energies and intrinsic anion oxidation potential of the molecules. Based on our calculations, we have found that ion pair dissociation energies and intrinsic anion oxidation potentials of the anions are mainly affected by the position and the type of substituents introduced into the parent structure. Compared to -CH3, substitution at the C2 position of the parent bis(trifluoroborane)benzimidazole (BTB(-)) by -CF3 results in an increase in anion oxidation stability. However, we observed a negligible change in the intrinsic anion oxidation potential as the length of the fluoroalkyl group increased to -C2F5. The most promising anions are generated by considering double-substitution at C2 and C5 positions. Among the possible anions, bis(trifluoroborane)-5-nitro-2-(trifluoromethyl) benzimidazolide (BTNTB(-)), with the calculated intrinsic anion oxidation potential of 5.50 V vs. Li(+)/Li, can be considered as a potential candidate for high voltage Li-ion batteries.

Ferroelectric BaTiO3 thin films on Ti substrate fabricated using pulsed-laser deposition.

We report on the fabrication of ferroelectric BaTiO3 thin films on titanium substrates using pulsed laser deposition and their microstructures and properties. Electron microscopy studies reveal that BaTiO3 films are composed of crystalline assemblage of nanopillars with average cross sections from 100 nm to 200 nm. The BaTiO3 films have good interface structures and strong adhesion with respect to Ti substrates by forming a rutile TiO2 intermediate layer with a gradient microstructure. The room temperature ferroelectric polarization measurements show that the as-deposited BTO films possess nearly the same spontaneous polarization as the bulk BTO ceramics indicating formation of ferroelectric domains in the films. Successful fabrication of such ferroelectric films on Ti has significant importance for the development of new applications such as structural health monitoring spanning from aerospace to civil infrastructure. The work can be extended to integrate other ferroelectric oxide films with various promising properties to monitor the structural health of materials.

Atomic structure of the Ag/Ge(111)-(sq.rt.(3) x sq.rt.(3)) surface: From scanning tunneling microscopy observation to theoretical study.

The atomic structure of the Ag/Ge(111)-(sq.rt.(3) x sq.rt.(3))R30 degrees surface is studied by scanning tunneling microscopy (STM) and the density functional theory (DFT) calculations. Our STM images have shown a structure which is different from the widely accepted honeycomb-chained-triangle (HCT) model before. The structure is similar to the inequivalent triangle (IET) model found for the Ag/Si(111)-(sq.rt.(3) x sq.rt(3))R30 degrees surface. This model proposed two types of silver triangles with different sizes in the unit cell, corresponding to the bright spots and the dark spots in the STM image. A distinguishable hexagonal pattern of the IET structure was well disclosed in the temperature range from 100 to 473 K in our STM studies for Ag/Ge(111)-(sq.rt.(3) x sq.rt.(3))R30 degrees. Furthermore, the result of the DFT calculations showed that the IET structure is 0.20 eV energetically more stable than the HCT model. Besides, the Ge triangles, which were not disclosed in earlier STM research, are found in this study.

Tribological behavior of nanocrystalline nickel.

During the last decade, an intensive investigative effort around the globe has been devoted to the understanding of scale effects on materials properties. In spite of their importance, nanoscale effects on tribological properties have attracted little attention. Such effects are of utmost importance to small scale devices such as nano and micro electromechanical systems that contain nanostructured dynamic components that would be difficult to replace or repair. The significant increase in strength arising from the grain size reduction in the nano domain is expected to impact on mechanical processes at asperity contacts that are dominating wear behavior. In the present work, nanocrystalline Ni produced by electroplating was used as a model system to study scale effects on tribological behavior. It was found that compared to bulk (microcrystalline), nanocrystalline Ni can cause a significant reduction in both, the coefficient of friction and wear rate. A consistent relationship was found between grain size, hardness and tribological behavior. It is suggested that the improved tribological behavior of the nanocrystalline Ni is due to the refinement of mechanical processes inhibiting plastic deformation by extensive dislocation motion leading to fracture events.

Microstructure evolution in amorphous Hf-B-Si-C-N high temperature resistant coatings after annealing to 1500 °C in air.

Recently, amorphous Hf-B-Si-C-N coatings found to demonstrate superior high-temperature oxidation resistance. The microstructure evolution of two coatings, Hf7B23Si22C6N40 and Hf6B21Si19C4N47, annealed to 1500 °C in air is investigated to understand their high oxidation resistance. The annealed coatings develop a two-layered structure comprising of the original as-deposited film followed by an oxidized layer. In both films, the oxidized layer possesses the same microstructure with HfO2 nanoparticles dispersed in an amorphous SiOx-based matrix. The bottom layer in the Hf6B21Si19C4N47 coating remains amorphous after annealing while Hf7B23Si22C6N40 recrystallized partially showing a nanocrystalline structure of HfB2 and HfN nanoparticles separated by h-Si3N4 and h-BN boundaries. The HfB2 and HfN nanostructures form a sandwich structure with a HfB2 strip being atomically coherent to HfN skins via (111)-Hf monolayers. In spite of the different bottom layer structure, the oxidized/bottom layer interface of both films was found to exhibit a similar microstructure with a fine distribution of HfO2 nanoparticles surrounded by SiO2 quartz boundaries. The high-temperature oxidation resistance of both films is attributed to the particular evolving microstructure consisting of HfO2 nanoparticles within a dense SiOx-based matrix and quartz SiO2 in front of the oxidized/bottom layer interface acting as a barrier for oxygen and thermal diffusion.

MiR-92a contributes to the cardiovascular disease development in diabetes mellitus through NF-κB and downstream inflammatory pathways.

OBJECTIVE: To explore the role of microRNA-92a (miR-92a) during the development of cardiovascular disease (CAD) in diabetes mellitus (DM) patients, and to investigate its correlation with NF-κB and downstream inflammatory cytokines in diabetes mellitus-associated cardiovascular disease (DM-CAD). PATIENTS AND METHODS: Expression of miR-92a in DM and DM-CAD patients was estimated by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Receiver operating characteristic (ROC) analysis was used to estimate the capability of miR-92a to discriminate between DM-CAD and DM patients. Nuclear factor-κB (NF-κB) p65 protein expression and serum concentrations of monocyte chemotactic protein-1 (MCP-1), endothelin-1 (ET-1) and intercellular adhesion molecule-1 (ICAM-1) were investigated. Correlations between miR-92a and NF-κB p65, inflammatory factors were assessed. Risk analysis based on miR-92a was performed for DM-CAD patients. RESULTS: MiR-92a expression was increased in DM-CAD group compared with both DM and healthy groups (all p<0.05). The expression of miR-92a was associated with FIB and HbA1c of DM-CAD patients. MiR-92a could be used to distinguish DM-CAD patients from DM patients with an area under the ROC curve (AUC) of 0.866. Moreover, miR-92a was demonstrated to be a risk factor for DM-CAD onset. Expression levels of NF-κB p65, ET-1, MCP-1, and ICAM-1 were all elevated in DM-CAD patients and shown positive correlations with miR-92a. CONCLUSIONS: Expression of miR-92a in DM-CAD patients is up-regulated, and serves as a potential marker to predict the CAD in DM patients. MiR-92a may contribute to the development of CAD through activation of NF-κB and downstream inflammatory pathways.

Ordered, self-organized cobalt nanodots in Co-diamond-like carbon thin films.

A formation process for ordered, self-organized cobalt (Co) nanodots in diamond-like carbon (DLC) thin films deposited by magnetron sputtering in a plasma-assisted Ar/CH4 discharge is presented. episilon-Co dots -5 nm in diameter, separated by 1-2 nm DLC boundaries and arranged in hexagonal arrays were produced on Si substrates. The formation mechanism relies on a self-organization process which is based on surface energy minimization and local magnetic field interaction. The proposed plasma-assisted process presents a controlled and cost-effective bottom-up nanofabrication approach for the production of well-ordered magnetic nanodots based on self-organization.

Distinct roles of processes modulated by histone deacetylases Rpd3p, Hda1p, and Sir2p in life extension by caloric restriction in yeast.

Caloric restriction has been demonstrated to extend life span and postpone aging in a variety of species. The recent extension of the caloric restriction paradigm to yeast places the emphasis of the search for the longevity effectors at the cellular level. To narrow the range of potential effectors of the caloric restriction response, we have examined the effects of the histone deacetylases Rpd3p, Hda1p, and Sir2p, which have distinguishable but partially overlapping influences on global patterns of gene expression, on the life extension afforded by caloric restriction. Deletion of the RPD3 gene extended life span, and there was no additive effect of caloric restriction. Deletion of HDA1 had no effect of its own on longevity but acted synergistically with caloric restriction to increase life span. SIR2 deletion shortened life span but did not prevent extension of life span by caloric restriction. The results suggest that Rpd3p affects both processes that play an obligate and those that play a synergistic role in life extension by caloric restriction, while Hda1p and Sir2p affect processes that are not the obligate longevity effectors of caloric restriction but instead synergize with them, although in opposite directions. From the known patterns of gene expression elicited by rpd3delta, hda1delta, and sir2delta, we propose that the major longevity effectors of caloric restriction in yeast involve carbohydrate/energy metabolism and mitochondrial function.

Call and skin glands secretion induced by stimulation of midbrain in urodele (Andrias davidianus).

Stimulation of the midbrain induced calls, gaping, tail lashing, locomotion and secretion of skin glands in the cryptobranchidae, Andrias davidianus, which is a rare precious animal in China. These responses can be considered as a complex of action related to escape. Most of the sites where calls and secretion of skin glands could be induced were found in the outside of central nucleus of the torus semicircularis. This is the first description of this cluster of functions in the midbrain of Andrias davidianus.

Mechanisms for dominance: Adh heterodimer formation in heterozygotes between ENU or X-ray induced null alleles and normal alleles in Drosophila melanogaster.

To study mechanisms for dominance of phenotype, eight ENU- and four X-ray-induced mutations at the alcohol dehydrogenase (Adh) locus were analyzed for partial dominance in their interaction with normal alleles. All ENU and one of the X-ray mutations were single base substitutions; the other three X-ray mutations were 9-21 base deletions. All but one of the 12 mutant alleles were selected for this study because they produced detectable mutant polypeptides, but seven of the 11 producing a peptide could not form dimers with the normal peptide and the enzyme activity of heterozygotes was about half that of normal homozygotes. Four mutations formed dimers with a decreased catalytic efficiency and two of these were near the limit of detectability; these two also inhibited the formation of normal homodimers. The mutant alleles therefore show multiple mechanisms leading to partial enzyme expression in heterozygotes and a wide range of dominance ranging from almost complete recessive to nearly dominant. All amino acid changes in mutant peptides that form dimers are located between amino acids 182 and 194, so this region is not critical for dimerization. It may, however, be an important surface domain for catalyzation.

Anorectic response to amino acid imbalance: a selective serotonin3 effect?

The anorectic responses to imbalanced amino acid diets (IMB) are ameliorated by pretreatment with large (mg/kg) doses of the serotonin antagonists, tropisetron [3-alpha-tropanyl-1H-indole-3-carboxylic acid ester, formerly known as ICS-205,930 (ICS)] and MDL 72,222 [1 alpha H,3 alpha,5 alpha-H-tropan-3-yl-3,5-dichlorobenzoate (MDL)], effects earlier attributed to the 5-hydroxytryptamine3 (5-HT3) receptor. Subsequent identification of the 5-HT4 receptor, and recognition that ICS and MDL also bind to 5-HT4 receptors, led us to question whether the results seen with these drugs were due to activity at the 5-HT3 or 5-HT4 receptor subtype. 1,2,3,9-Tetrahydro-9-methyl-3 [(2-methyl-1H-imidazol-1-yl) methyl] 4H-carbazol-4-one) [ondansetron (OND)], a reportedly 5-HT3-selective receptor antagonist, has been used to block 5-HT3 receptors in demonstrating the 5-HT4 receptor, and so seems securely selective for the 5-HT3 receptor type. Therefore, we tested the effects of OND on the rat's feeding responses to IMB. Pretreatment with 0.1 or 1 micrograms/kg OND fully restored intake of IMB to > 100% of control between 6 and 12 h after introduction of IMB. We conclude that the previous similar increases in IMB intake seen after ICS and MDL were due to their antagonist activity at the 5-HT3 receptor and that the 5-HT3 receptor may have an important role in mediating the rat's anorectic responses to IMB.

Mesoporous SnO2 synthesized with non-ionic surfactants as an anode material for lithium batteries.

Mesoporous tin oxides were successfully prepared with the use of non-ionic surfactants, Pluronic 123 (P-123) and Tetronic 908 (T-908). Surface analysis of SnO2 synthesized with P123 showed an average pore size of approximately 15 nm. The high-resolution transmission electron microscopy and low-angle X-ray diffraction (XRD) measurements also confirmed their mesoporous nature. The X-ray photoelectron spectroscopy and wide-angle XRD studies revealed that these compounds have a casserite-type SnO2 structure. The electrochemical properties of these materials as anodes in lithium batteries showed excellent performance with good reversibility. The first-cycle reversible capacity was 1026 mAh/g for the material synthesized with P123. There was a high first-cycle irreversible capacity for SnO2 synthesized with the use of both non-ionic surfactants. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed to study the electrode kinetics during the lithium insertion process in the first cycle. There was a decrease in the charge-transfer resistance with respect to the discharge potential. The synthesis and structural and electrochemical properties of the mesoporous tin oxides are correlated and discussed in detail.

Nanocrystalline sensor-grade Sn1-xInxO2 (0 < or = x < or = 0.2).

Nanocrystalline Sn1-xInxO2 (0 < or = x < or = 0.2) has been successfully prepared by a solution chemical route. High-resolution transmission electron microscopy studies show that the average grain size of Sn0.8In0.2O2 heated at 310 degrees C, 500 degrees C, and 800 degrees C for 12 h is about 3-4 nm, 5-6 nm, and 7-10 nm, respectively. The corresponding values for pure SnO2 are 3-4 nm, 7-10 nm, and 50-90 nm, respectively. Powder X-ray diffraction and electron diffraction studies confirm the existence of solid solution only in the nanocrystalline state (the average particle size is in the range of 5-10 nm) with the solubility limited to 20% of In2O3. Indium ions stabilize the nanocrystalline nature of Sn1-xInxO2 (0 < or = x < or = 0.2) and prevent the grain growth by entering the SnO2 lattice. The thermal characteristics of nanocrystalline Sn1-xInxO2 (0 < or = x < or = 0.2) investigated by thermogravimetric (TG) and differential thermal analysis (DTA) show that the solid solution decomposes at 820 degrees C into SnO2 and In2O3, which is accompanied by a rapid crystal growth. The electrical conductivity and activation energy of Sn1-xInxO2 (0 < or = x < or = 0.2) undergo significant changes when the average grain size is less than or equal to 2 x the Debye length, LD.

[The heterozygous effect of X-ray or ENU-induced null-mutant Adh alleles on alcohol tolerance of Drosophila melanogaster].

To study the mechanisms of partial dominance, 12 intragenic alcohol dehydrogenase null mutations (Adhn) in Drosophila melanogaster were used as a model system. These known sequenced mutations, either single base substitutions or small intragenic deletions (9-16 bp) were analyzed for peptide production, dimer formation and enzymatic activity of the heterodimer. Multiple mechanisms leading to partial enzyme expression in heterozygotes and a wide range of dominance varying from almost complete recessive to a high degree of dominance were found. An expression of partial dominance for alcohol tolerance was observed for all 12 Adhn under the high stress of 10% ethanol. The genetic background on which the null mutations are expressed is a major determinant for alcohol tolerance of the heterozygous adult flies. The mutations induced by X-ray had higher average dominance than that of ENU-induced mutations, and the mutations that formed nonfunctional heterodimers had the highest dominance.