Dilemma in All-optical Characterization of Single-layer NiI2 Multiferroics

Matters Arising in Nature on "Evidence for a single layer van der Waals multiferroic". The search for two dimensional multiferroic materials is an exciting yet challenging endeavor. Recently, Song reported the exciting discovery of type II multiferroic order in an antiferromagnetic (AFM) NiI2 single layer and concluded the ferroelectric (FE) polarization induced by a helical magnetic order1. Their finding was presented from all optical experimental evidence, based on the methods of second harmonic generation (SHG) and linear dichroism (LD). However, the all optical characterizations cannot serve as unanimous evidence of the FE existence, particularly in conjunction with magnetic orders in a single layer NiI2 multiferroic. We have designed and built a Magneto-Optical-Electric Joint-measurement Scanning Imaging system (MOEJSI) for identification of two-dimensional vdW multiferroic.Comment: 7 page

Peroxo Species Formed in the Bulk of Silicate Cathodes

Oxygen redox in Li‐rich oxides may boost the energy density of lithium‐ion batteries by incorporating oxygen chemistry in solid cathodes. However, oxygen redox in the bulk usually entangles with voltage hysteresis and oxygen release, resulting in a prolonged controversy in literature on oxygen transformation. Here, we report spectroscopic evidence of peroxo species formed and confined in silicate cathodes amid oxygen redox at high voltage, accompanied by Co$^{2+}$/Co$^{3+}$ redox dominant at low voltage. First‐principles calculations reveal that localized electrons on dangling oxygen drive the O‐O dimerization. The covalence between the binding cation and the O‐O dimer determines the degree of electron transfer in oxygen transformation. Dimerization induces irreversible structural distortion and slow kinetics. But peroxo formation can minimize the voltage drop and volume expansion in cumulative cationic and anionic redox. These findings offer insights into oxygen redox in the bulk for the rational design of high‐energy‐density cathodes

Advances and Prospects in Integrated Nano-oncology

In recent years, the deep integration of basic research and clinical translational research of nanotechnology and oncology has led to the emergence of a new branch, namely integrated nano-oncology. This is an emerging and important interdisciplinary field, which plays an irreplaceable role in the diagnosis, treatment, early warning, monitoring and prevention of tumors, and has become a new interdisciplinary frontier. Here main advances of integrated nano-oncology was reviewed, mainly included controlled preparation of nanomaterials, ultra-sensitive detection of tumor biomarkers, multi-functional nanoimaging probes and integrated diagnosis and treatment technology, innovative nano drugs and nano drug delivery system, DNA nanotechnology, RNA nanotechnology, nano self-assembly technology, nanosensors, intelligent nanorobots, nanotherapeutic machines. The terms, concepts, trends and challenges are also discussed with the aim of promoting the application of nanotechnology in integrated oncology and solving the scientific and key technical problems in basic and clinical translational research of cancer

Concept and Evaluation of a New Piezoelectric Transducer for an Implantable Middle Ear Hearing Device

Implantable middle ear hearing devices (IMEHDs) have been developed as a new technology to overcome the limitations of conventional hearing aids. The piezoelectric cantilever transducers currently used in the IMEHDs have the advantages of low power consumption and ease of fabrication, but generate less high-frequency output. To address this problem, we proposed and designed a new piezoelectric transducer based on a piezoelectric stack for the IMEHD. This new transducer, attached to the incus body with a coupling rod, stimulates the ossicular chain in response to the expansion-and-contraction of its piezoelectric stack. To test its feasibility for hearing loss compensation, a bench testing of the transducer prototype and a temporal bone experiment were conducted, respectively. Bench testing results showed that the new transducer did have a broad frequency bandwidth. Besides, the transducer was found to have a low total harmonic distortion (<0.75%) in all frequencies, and small release time (1 ms). The temporal bone experiment further proved that the transducer has the capability to produce sufficient vibrations to compensate for severe sensorineural hearing loss, especially at high frequencies. This property benefits the treatment of the most common sloping high-frequency sensorineural hearing loss. To produce a 100 dB SPL equivalent sound pressure at 1 kHz, its power consumption is 0.49 mW, which is low enough for the transducer to be utilized in the IMEHD

A Simulation Study on the Flow Behavior of Liquid Steel in Tundish with Annular Argon Blowing in the Upper Nozzle

A three-dimensional mathematical model of gas−liquid two-phase flow has been established to study the flow behavior of liquid steel in the tundish. The effect of the argon flow rate and casting speed on the flow behavior of liquid steel, as well as the migration behavior of argon bubbles, was investigated. The results from the mathematical model were found to be consistent with those from the tundish water model. There were some swirl flows around the stopper when the annular argon blowing process was adopted; the flow of liquid steel near the liquid surface was active around the stopper. With increased argon flow rate, the vortex range and intensity around the stopper gradually increased, and the vertical flow velocity of the liquid steel in the vicinity of the stopper increased; the argon volume flow in the tundish and mold all increased. With increased casting speed, the vortex range and intensity around the stopper gradually decreased, the peak value of vertical flow velocity of liquid steel at the vicinity of the stopper decreased, and the distribution and ratio of argon volume flow between the tundish and the mold decreased. To avoid slag entrapment and purify the liquid steel, the argon flow rate should not be more than 3 L·min−1. These results provide a theoretical basis to optimize the parameters of the annular argon blowing at the upper nozzle and improve the slab quality

Slow-Relaxation Behavior of a Mononuclear Co(II) Complex Featuring Long Axial Co-O Bond

Co(II) mononuclear complex with different coordination geometry would display various of field-induced single-ion magnet (SIM) behaviors. Here, we identify a field-induced single-ion magnet in a mononuclear complex Co(H2DPA)2·H2O (H2DPA = 2,6-pyridine-dicarboxylic acid) by the hydrothermal method. The long axial Co-O coordination bond (Co1‧‧‧O3) can be formed by Co1 and O3. Therefore, Co(II) ion is six-coordinated in a distorted elongated octahedron. AC magnetization susceptibilities show that the effective energy barrier is up to 43.28 K. This is much larger than most mononuclear Co(II). The distorted elongated octahedron caused by the axial Co-O coordination bond is responsible for the high effective energy barrier. The distribution of electron density in Co1 and O3 atoms in the long axial bond would influence the magnetic relaxation process in turn. Our work deepens the relationship between the effective energy barrier and the weak change of ligand field by long axial bonds, which would facilitate constructing SIM with high energy temperature

Enhancing Photoluminescence of CsPb(ClxBr1−x)3 Perovskite Nanocrystals by Fe2+ Doping

The doping of impurity ions into perovskite lattices has been scrupulously developed as a promising method to stabilize the crystallographic structure and modulate the optoelectronic properties. However, the photoluminescence (PL) of Fe2+-doped mixed halide perovskite NCs is still relatively unexplored. In this work, the Fe2+-doped CsPb(ClxBr1−x)3 nanocrystals (NCs) are prepared by a hot injection method. In addition, their optical absorption, photoluminescence (PL), PL lifetimes, and photostabilities are compared with those of undoped CsPb(Br1−xClx)3 NCs. We find the Fe2+ doping results in the redshift of the absorption edge and PL. Moreover, the full width at half maximums (FWHMs) are decreased, PL quantum yields (QYs) are improved, and PL lifetimes are extended, suggesting the defect density is reduced by the Fe2+ doping. Moreover, the photostability is significantly improved after the Fe2+ doping. Therefore, this work reveals that Fe2+ doping is a very promising approach to modulate the optical properties of mixed halide perovskite NCs

Enhanced Response for Foodborne Pathogens Detection by Au Nanoparticles Decorated ZnO Nanosheets Gas Sensor

Listeria monocytogenes is a hazardous foodborne pathogen that is able to cause acute meningitis, encephalitis, and sepsis to humans. The efficient detection of 3-hydroxy-2-butanone, which has been verified as a biomarker for the exhalation of Listeria monocytogenes, can feasibly evaluate whether the bacteria are contained in food. Herein, we developed an outstanding 3-hydroxy-2-butanone gas sensor based on the microelectromechanical systems using Au/ZnO NS as a sensing material. In this work, ZnO nanosheets were synthesized by a hydrothermal reaction, and Au nanoparticles (~5.5 nm) were prepared via an oleylamine reduction method. Then, an ultrasonic treatment was carried out to modified Au nanoparticles onto ZnO nanosheets. The XRD, BET, TEM, and XPS were used to characterize their morphology, microstructure, catalytic structure, specific surface area, and chemical composition. The response of the 1.0% Au/ZnO NS sensors vs. 25 ppm 3-hydroxy-2-butanone was up to 174.04 at 230 °C. Moreover, these sensors presented fast response/recovery time (6 s/7 s), great selectivity, and an outstanding limit of detection (lower than 0.5 ppm). This work is full of promise for developing a nondestructive, rapid and practical sensor, which would improve Listeria monocytogenes evaluation in foods

Trends in traumatic brain injury mortality in China, 2006-2013: A population-based longitudinal study.

BACKGROUND:Traumatic brain injury (TBI) is a significant global public health problem, but has received minimal attention from researchers and policy-makers in low- and middle-income countries (LMICs). Epidemiological evidence of TBI morbidity and mortality is absent at the national level for most LMICs, including China. Using data from China's Disease Surveillance Points (DSPs) system, we conducted a population-based longitudinal analysis to examine TBI mortality, and mortality differences by sex, age group, location (urban/rural), and external cause of injury, from 1 January 2006 to 31 December 2013 in China. METHOD AND FINDINGS:Mortality data came from the national DSPs system of China, which has coded deaths using the International Classification of Diseases-10th Revision (ICD-10) since 2004. Crude and age-standardized mortality with 95% CIs were estimated using the census population in 2010 as a reference population. The Cochran-Armitage trend test was used to examine the significance of trends in mortality from 2006 to 2013. Negative binomial models were used to examine the associations of TBI mortality with location, sex, and age group. Subgroup analysis was performed by external cause of TBI. We found the following: (1) Age-adjusted TBI mortality increased from 13.23 per 100,000 population in 2006 to 17.06 per 100,000 population in 2008 and then began to fall slightly. In 2013, age-adjusted TBI mortality was 12.99 per 100,000 population (SE = 0.13). (2) Compared to females and urban residents, males and rural residents had higher TBI mortality risk, with adjusted mortality rate ratios of 2.57 and 1.71, respectively. TBI mortality increased substantially with older age. (3) Motor vehicle crashes and falls were the 2 leading causes of TBI mortality between 2006 and 2013. TBI deaths from motor vehicle crashes in children aged 0-14 years and adults aged 65 years and older were most often in pedestrians, and motorcyclists were the first or second leading category of road user for the other age groups. (4) TBI mortality attributed to motor vehicle crashes increased for pedestrians and motorcyclists in all 7 age groups from 2006 to 2013. Our analysis was limited by the availability and quality of data in the DSPs dataset, including lack of injury-related socio-economic factors, policy factors, and individual and behavioral factors. The dataset also may be incomplete in TBI death recording or contain misclassification of mortality data. CONCLUSIONS:TBI constitutes a serious public health threat in China. Further studies should explore the reasons for the particularly high risk of TBI mortality among particular populations, as well as the reasons for recent increases in certain subgroups, and should develop solutions to address these challenges. Interventions proven to work in other cultures should be introduced and implemented nationwide. Examples of these in the domain of motor vehicle crashes include policy change and enforcement of laws concerning helmet use for motorcyclists and bicyclists, car seat and booster seat use for child motor vehicle passengers, speed limit and drunk driving laws, and alcohol ignition interlock use. Examples to prevent falls, especially among elderly individuals, include exercise programs, home modification to reduce fall risk, and multifaceted interventions to prevent falls in all age groups

The Aqueous Extract of Gynura divaricata

Type 2 diabetes mellitus (T2DM) is a chronic disease characterized by hyperglycemia and dyslipidemia caused by impaired insulin secretion and resistance of the peripheral tissues. A major pathogenesis of T2DM is obesity-associated insulin resistance. Gynura divaricata (L.) DC. (GD) is a natural plant and has been reported to have numerous health-promoting effects on both animals and humans. In this study, we aimed to elucidate the regulatory mechanism of GD improving glucose and lipid metabolism in an obesity animal model induced by high-fat and high-sugar diet in combination with low dose of streptozocin and an insulin-resistant HepG2 cell model induced by dexamethasone. The study showed that the water extract of GD (GD extract A) could significantly reduce fasting serum glucose, reverse dyslipidemia and pancreatic damage, and regulate the body weight of mice. We also found that GD extract A had low toxicity in vivo and in vitro. Furthermore, GD extract A may increase glucose consumption in insulin-resistant HepG2 cells, markedly inhibit NF-κB activation, and decrease the impairment in signaling molecules of insulin pathway, such as IRS-1, AKT, and GLUT1. Overall, the results indicate that GD extract A is a promising candidate for the prevention and treatment of T2DM