An artificial visual neuron with multiplexed rate and time-to-first-spike coding.

Human visual neurons rely on event-driven, energy-efficient spikes for communication, while silicon image sensors do not. The energy-budget mismatch between biological systems and machine vision technology has inspired the development of artificial visual neurons for use in spiking neural network (SNN). However, the lack of multiplexed data coding schemes reduces the ability of artificial visual neurons in SNN to emulate the visual perception ability of biological systems. Here, we present an artificial visual spiking neuron that enables rate and temporal fusion (RTF) coding of external visual information. The artificial neuron can code visual information at different spiking frequencies (rate coding) and enables precise and energy-efficient time-to-first-spike (TTFS) coding. This multiplexed sensory coding scheme could improve the computing capability and efficacy of artificial visual neurons. A hardware-based SNN with the RTF coding scheme exhibits good consistency with real-world ground truth data and achieves highly accurate steering and speed predictions for self-driving vehicles in complex conditions. The multiplexed RTF coding scheme demonstrates the feasibility of developing highly efficient spike-based neuromorphic hardware.

The impact of financial technology on China's low-carbon transformation of energy and mechanism analysis.

Financial technology provides strong support for the low-carbon transformation of energy through digital technology. There is limited research on the relationship between financial technology and low-carbon transformation of energy, and the information transmission and connection between the two entities are still unclear. Therefore, this paper innovatively conducts in-depth research on the spatial effect between financial technology and low-carbon transformation of energy and further analyzes the intermediary role of green finance in it. Firstly, the spatial Durbin model and spatial intermediary effect model between financial technology and low-carbon transformation of energy are constructed. Then, based on the Moran coefficient, the spatial effects of low-carbon transformation in financial technology and energy were analyzed. Finally, an empirical study was conducted using the panel data of China's provinces from 2011 to 2020. The results show that financial technology can effectively promote the energy transformation, and financial technology and the degree of low-carbon transformation of energy have significant spatial effects. From the perspective of intermediary effect, financial technology can effectively improve the green finance structure and promote low-carbon transformation of energy. From the perspective of spatial intermediary effect, while promoting the development of green finance in the local area, financial technology will also suppress the development of green finance in surrounding areas, thereby inhibiting the low-carbon transformation of energy in the surrounding areas. Therefore, China should strengthen the development of financial science and technology, guide the transformation of traditional finance, improve the coverage of green finance, and realize the low-carbon transformation of national energy.

Can work-to-family conflict lead to preschool children's social behavior problems?-The chain mediating roles of guilt about parenting and parent-child relationships.

Parents' work-to-family conflict has been reported to be associated with preschool children's social behavior problems, but the underlying mechanisms of this association in the Chinese cultural context remain unclear. Based on ecosystem theory and the spillover-crossover model theory of emotion, this study aimed to examine the correlation between parents' work-to-family conflict and preschool children's social behavior problems in China, as well as the mediating role of guilt about parenting and parent-child relationships. Structural equation modeling was used to check the research hypotheses with a sample of 3,038 parents of Chinese preschool children. The main findings of this study are as follows: (1) Work-to-family conflict faced by parents was positively associated with guilt about parenting and preschool children's social behavior problems; (2) The effect of guilt about parenting on preschool children's social behavior problems was bidirectional; guilt about parenting was positively related to preschool children's social behavior problems, but when guilt about parenting prompted parents to adjust their parent-child relationships, it was negatively related to preschool children's social behavior problems. Taken together, these results further explain the interaction between parents' work-to-family conflict and preschool children's social behavior problems and discuss the influence of multiple factors on preschool children's social behavior problems. Theoretically, this study enriches the theoretical basis of the interaction with resources from the external environment of home education and family education. Practically, it implies that multiple levels, such as the government, early childhood education institutions, and work units, should give more support to preschool children's family education and thus work together to promote the healthy development of preschool children.

Driving factors of NOX emission reduction in China's power industry: based on LMDI decomposition model.

Under the policy background of "joint prevention and control" of global greenhouse gas emission reduction and regional air pollutants, the power industry, as an important target industry of energy conservation and emission reduction policies, has become an effective choice to release dual pressures. In this paper, the "bottom-up" emission factor method was used to measure the emission of CO2 and NOX from 2011 to 2019. Then, the contributions of six factors to NOX emission reduction in China's power industry were identified using the Kaya identity and logarithmic mean divisia index (LMDI) decomposition methods. The research results show that (1) there is a significant synergistic emission reduction effect between CO2 emission reduction and NOX emission reduction; (2) the factor that inhibits the growth of NOX emissions reduction in the power industry is economic development factor; and (3) the main factors that promote the reduction of NOX emission from the power industry are synergy effect, energy intensity, power generation intensity, and power production structure factors. Several suggestions are proposed, which are the power industry should adjust its structure, improve energy intensity, focus on applying low-nitrogen combustion technology, and improve the air pollutant emission information disclosure system to reduce NOX emissions.

Coupling coordination analysis of low-carbon development, technology innovation, and new urbanization: Data from 30 provinces and cities in China.

Technology innovation capability as an endogenous driving force plays an increasingly important role in the low-carbon transformation of new urbanization. This paper's purpose is to delve into the coupling coordination relationship among the three variables, and promote system's and region's synergy development. Based on the coupling coordination degree model, spatial autocorrelation model and obstacle degree model, this paper investigated the coupling coordination of low-carbon development (LCD) quality, technology innovation (TI) capability and new urbanization (NU) level in China from 2009 to 2019. The results indicate: (1) The coupling coordination degree (CCD) of LCD quality, TI capability and NU level in all regions of the country were fluctuating for a long time, and the regions that reach the coordinated development level showed a slow rising trend with obvious regional differences. (2) Three subsystems' CCD showed significant spatial correlation characteristics, and the degree of spatial agglomeration was constantly increasing. (3) The obstacles affecting the systems' synergy mainly reflected in economic and social indexes. In the end, this paper proposed that policy coordination and linkage should be strengthened, emphasizing the integrated development of the three subsystems. It is necessary to formulate development plans in combination with geographic location and resource endowment to enhance the regional driving effect.

Overexpression of FOXD2-AS1 enhances proliferation and impairs differentiation of glioma stem cells by activating the NOTCH pathway via TAF-1.

Emerging data have highlighted the importance of long noncoding RNAs (lncRNAs) in exerting critical biological functions and roles in different forms of brain cancer, including gliomas. In this study, we sought to investigate the role of lncRNA FOXD2 adjacent opposite strand RNA 1 (FOXD2-AS1) in glioma cells. First, we used sphere formation assay and flow cytometry to select U251 glioma stem cells (GSCs). Then, we quantified the expression of lncRNA FOXD2-AS1, TATA-box binding protein associated factor 1 (TAF-1) and NOTCH1 in glioma tissues and GSCs, as well as the expression of GSC stem markers, OCT4, SOX2, Nanog, Nestin and CD133 in GSCs. Colony formation assay, sphere formation assay, and flow cytometry were used to evaluate GSC stemness. Next, the correlations among lncRNA FOXD2-AS1, TAF-1 and NOTCH1 were investigated. LncRNA FOXD2-AS1, TAF-1 and NOTCH1 were found to be elevated in glioma tissues and GSCs, and silencing lncRNA FOXD2-AS1 inhibited stemness and proliferation, while promoting apoptosis and differentiation of GSCs. LncRNA FOXD2-AS1 overexpression also led to increased NOTCH1 by recruiting TAF-1 to the NOTCH1 promoter region, thereby promoting stemness and proliferation, while impairing cell apoptosis and differentiation. Mechanistically, lncRNA FOXD2-AS1 elevation promoted glioma in vivo by activating the NOTCH signalling pathway via TAF-1 upregulation. Taken together, the key findings of our investigation support the proposition that downregulation of lncRNA FOXD2-AS1 presents a viable and novel molecular candidate for improving glioma treatment.

Electro-optic polymer and silicon nitride hybrid spatial light modulators based on a metasurface.

Spatial light modulators (SLMs) are important for various applications in photonics, such as near-infrared imaging, beam steering and optical communication. After decades of advances, current commercial devices are typically limited to kilohertz modulating speeds. To realize higher operating speeds, an electro-optic (EO) polymer and silicon nitride hybrid SLM has been demonstrated in this work. We utilize a specially designed metasurface to support a relatively high quality resonance and simultaneously confine most of the incident light in the active EO polymer layer. Combing with the high EO coefficient of the polymer, a clear modulation at 10 MHz with a driving voltage of Vp-p=±10 V has been observed in the proof-of-concept device. Our first-generation device leaves vast room for further improvement and may open an attractive route towards compact SLM with an RF modulation higher than 100 GHz.

Gas environment independent temperature sensor via double-metal surface plasmon resonance.

As the sensitivity of the optical temperature sensor increases, one of the most important noise sources may be from the fluctuation of the surrounding gas environment (refractive index change). In this work, we have designed and fabricated an optical temperature sensor with a device size of 15 µm2. The sensor is constructed by a titanium dioxide grating on top of a double-metal surface plasmon resonance (SPR) structure. Our design can provide minimal gas environment dependence without compromising the performance in terms of temperature sensitivity. In addition, the design also facilitates a generous dimensional tolerance in the device fabrication. Based on the design, a proof-of-concept device has been fabricated and characterized. The obtained sensitivity of the fabricated sensor reaches 135 pm/℃. Meanwhile, the measured resonance wavelength shift is ∼0.004 pm in different gases (air, CH4, and CO2). The presented temperature sensor should be convenient and valuable for high-accuracy temperature measurements and integrated opto-electronic sensing chips.

Design and theoretical characterization of high speed metasurface modulators based on electro-optic polymer.

Metasurfaces have attracted extraordinary interest in achieving novel, ultrathin and compact photonic devices. To date, however, the realization of electrically tunable high-speed metasurfaces remains a great challenge. In this work, we present an electro-optic (EO) polymer/silicon hybrid metasurface modulator with an estimated 3dB modulation bandwidth up to 118 GHz. The specially designed metasurface utilizes a broken in-plane inversion symmetry structure to generate a high-Q resonance. The high-Q property enhances the EO modulation effect, so that a 16 dB extinction ratio is theoretically verified under a driving voltage Vp-p of 4V. The pulse modulation results in an ultra-fast single-lane data rates up to 300 Gbps driven by a low RF power. The presented modulator should be applicable for high-speed and low-energy intelligent tunable metasurface, space optical communication and so on.

Electrically tunable tunneling rectification magnetoresistance in magnetic tunneling junctions with asymmetric barriers.

The development of multifunctional spintronic devices requires simultaneous control of multiple degrees of freedom of electrons, such as charge, spin and orbit, and especially a new physical functionality can be realized by combining two or more different physical mechanisms in one specific device. Here, we report the realization of novel tunneling rectification magnetoresistance (TRMR), where the charge-related rectification and spin-dependent tunneling magnetoresistance are integrated in Co/CoO-ZnO/Co magnetic tunneling junctions with asymmetric tunneling barriers. Moreover, by simultaneously applying direct current and alternating current to the devices, the TRMR has been remarkably tuned in the range from -300% to 2200% at low temperature. This proof-of-concept investigation provides an unexplored avenue towards electrical and magnetic control of charge and spin, which may apply to other heterojunctions to give rise to more fascinating emergent functionalities for future spintronics applications.

Defect introduced paramagnetism and weak localization in two-dimensional metal VSe2.

We have carried out a detailed investigation of the magnetism, valence state, and magnetotransport in VSe2 bulk single crystals, as well as in laminates obtained by mechanical exfoliation. In sharp contrast to the ferromagnetic behavior reported previously, here, no ferromagnetism could be detected for VSe2 single crystal and laminate from room temperature down to 2 K. Neither did we find the Curie paramagnetism expected due to the 3d 1 odd-electronic configuration of covalent V4+ ions. Rather, intrinsic VSe2 is a non-magnetic alloy without local moment. Only a weak paramagnetic contribution introduced by defects is noticeable below 50 K. A weak localization effect due to defects was also observed in VSe2 single crystals for the first time.

Oxygen vacancies controlled multiple magnetic phases in epitaxial single crystal Co0.5(Mg0.55Zn0.45)0.5O(1-v) thin films.

High quality single-crystal fcc-Co(x)(Mg(y)Zn(1-y))(1-x)O(1-v) epitaxial thin films with high Co concentration up to x = 0.5 have been fabricated by molecular beam epitaxy. Systematic magnetic property characterization and soft X-ray absorption spectroscopy analysis indicate that the coexistence of ferromagnetic regions, superparamagnetic clusters, and non-magnetic boundaries in the as-prepared Co(x)(Mg(y)Zn(1-y))(1-x)O(1-v) films is a consequence of the intrinsic inhomogeneous distribution of oxygen vacancies. Furthermore, the relative strength of multiple phases could be modulated by controlling the oxygen partial pressure during sample preparation. Armed with both controllable magnetic properties and tunable band-gap, Co(x)(Mg(y)Zn(1-y))(1-x)O(1-v) films may have promising applications in future spintronics.

Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions.

Magnetoresistance and rectification are two fundamental physical properties of heterojunctions and respectively have wide applications in spintronics devices. Being different from the well known various magnetoresistance effects, here we report a brand new large magnetoresistance that can be regarded as rectification magnetoresistance: the application of a pure small sinusoidal alternating-current to the nonmagnetic Al/Ge Schottky heterojunctions can generate a significant direct-current voltage, and this rectification voltage strongly varies with the external magnetic field. We find that the rectification magnetoresistance in Al/Ge Schottky heterojunctions is as large as 250% at room temperature, which is greatly enhanced as compared with the conventional magnetoresistance of 70%. The findings of rectification magnetoresistance open the way to the new nonmagnetic Ge-based spintronics devices of large rectification magnetoresistance at ambient temperature under the alternating-current due to the simultaneous implementation of the rectification and magnetoresistance in the same devices.

Electrical control of memristance and magnetoresistance in oxide magnetic tunnel junctions.

Electric-field control of magnetic and transport properties of magnetic tunnel junctions has promising applications in spintronics. Here, we experimentally demonstrate a reversible electrical manipulation of memristance, magnetoresistance, and exchange bias in Co/CoO-ZnO/Co magnetic tunnel junctions, which enables the realization of four nonvolatile resistance states. Moreover, greatly enhanced tunneling magnetoresistance of 68% was observed due to the enhanced spin polarization of the bottom Co/CoO interface. The ab initio calculations further indicate that the spin polarization of the Co/CoO interface is as high as 73% near the Fermi level and plenty of oxygen vacancies can induce metal-insulator transition of the CoO(1-v) layer. Thus, the electrical manipulation mechanism on the memristance, magnetoresistance and exchange bias can be attributed to the electric-field-driven migration of oxygen ions/vacancies between very thin CoO and ZnO layers.

A high performance quasi-solid-state self-powered UV photodetector based on TiO2 nanorod arrays.

Self-powered UV photodetectors based on TiO2 and ZnO nanorod arrays have attracted lots of attention in recent years due to their various advantages. Impressive performances were observed in photochemical cell based UV detectors. However, liquid electrolytes are not ideal for long-term operation and are inconvenient for practical applications. Hence there is an urgent demand for replacing liquid electrolytes with solid-state hole transfer materials. Herein we report a nanostructured quasi-solid-state UV photodetector fabricated using a liquid crystal (LC)-embedded electrolyte with a light-trapping scheme. Vertical rutile TiO2 nanorod arrays grown on fluorine-doped tin oxide conductive glass were used as the active photoanode. A high incident photon-to-current conversion efficiency of 29% at 383 nm and a quick response time of less than 0.03 s were observed. In addition, it was revealed that the quasi-solid-state UV photodetector showed visible-blind, high responsivity, fast time response and good photosensitivity linearity in a wide light intensity range. The LC-embedded electrolyte with a light-trapping scheme enhanced the light absorption and thus improved the photodetecting performance. This self-powered device is a promising candidate for application in high-sensitivity and high-speed UV light photodetectors.

High-performance self-powered UV photodetectors based on TiO2 nano-branched arrays.

Nano-branched TiO2 arrays were fabricated on fluorine-doped tin oxide (FTO) glass by a facile two-step chemical synthesis process. Self-powered UV photodetectors based on photoelectrochemical cells (PECs) were assembled using these TiO2 nano-branched arrays as photoanodes. These visible-blind self-powered UV photodetectors exhibit high sensitivity and high-speed photoresponse. Compared with photodetectors based on bare TiO2 nanorod arrays, TiO2 nano-branched arrays show drastically improved photodetecting performance as photoanodes. The photosensitivity increases from 0.03 to 0.22 A W(-1) when optimized nano-branched TiO2 arrays are used, corresponding to an incident photon-to-current conversion efficiency higher than 77%. The UV photodetectors also exhibit excellent spectral selectivity and fast response (0.05 s decay time). The improved performance is attributed to a markedly enlarged TiO2/electrolyte contact area and good electron conductivity in the one-dimensional, well-aligned TiO2 nanorod trunk.

Spin memristive magnetic tunnel junctions with CoO-ZnO nano composite barrier.

The spin memristive devices combining memristance and tunneling magnetoresistance have promising applications in multibit nonvolatile data storage and artificial neuronal computing. However, it is a great challenge for simultaneous realization of large memristance and magnetoresistance in one nanoscale junction, because it is very hard to find a proper spacer layer which not only serves as good insulating layer for tunneling magnetoresistance but also easily switches between high and low resistance states under electrical field. Here we firstly propose to use nanon composite barrier layers of CoO-ZnO to fabricate the spin memristive Co/CoO-ZnO/Co magnetic tunnel junctions. The bipolar resistance switching ratio is high up to 90, and the TMR ratio of the high resistance state gets to 8% at room temperature, which leads to three resistance states. The bipolar resistance switching is explained by the metal-insulator transition of CoO(1-v) layer due to the migration of oxygen ions between CoO(1-v) and ZnO(1-v).

[Meta-analysis of association between MMP-1-1607 polymorphism and head and neck cancer risk in asia population].

OBJECTIVE: To analyze and explore the association between the 1607(1G/2G) single nucleotide polymorphism (SNP) in promoter of matrix metalloproteinase-1 (MMP-1) gene and susceptibility of head and neck cancer (HNC) by Meta-analysis. METHOD: By the end of January 2014, the published literatures were collected for the case-control studies evaluating the relationship between HNC and -1607 SNP of MMP-1 gene from English and Chinese literature databases according to the inclusion and exclusion criteria. Then the meta-analysis, the heterogeneity, bias and sensitivity of the results of the eligible literatures were conducted by Stata 10. 0. RESULT: A total of 9 studies including 2049 patients with HNC and 2158 controls were extracted for systematic review on the association of MMP-1 (-1607) 1G/2G SNP with the risk of HNC. Meta-analysis which based on random effects model showed that MMP-1 (-1607) 1G/2G SNP can significantly increase the risk of HNC[1G2G + 2G2G vs. 1G1G: OR = 1.45, 95% CI 1.25-1.68, P < 0.01; 2G2G vs. 1G1G + 1G2G:OR = 1.77, 95% CI 1.37-2.30, P < 0.01; 2G vs. 1G: OR = 1.52, 95% CI 1.26-1.85, P < 0.01; 2G2G vs. 1G1G: OR = 2.06, 95% CI 1.41-3.01, P < 0.01). CONCLUSION: MMP-1 (-1607) 1G/2G SNP has close relationship with HNC susceptibility, people who with 2G2G genotype carriers are susceptible to HNC.

ZnO nanoneedle/H2O solid-liquid heterojunction-based self-powered ultraviolet detector.

ZnO nanoneedle arrays were grown vertically on a fluorine-doped tin oxide-coated glass by hydrothermal method at a relatively low temperature. A self-powered photoelectrochemical cell-type UV detector was fabricated using the ZnO nanoneedles as the active photoanode and H2O as the electrolyte. This solid-liquid heterojunction offers an enlarged ZnO/water contact area and a direct pathway for electron transport simultaneously. By connecting this UV photodetector to an ammeter, the intensity of UV light can be quantified using the output short-circuit photocurrent without a power source. High photosensitivity, excellent spectral selectivity, and fast photoresponse at zero bias are observed in this UV detector. The self-powered behavior can be well explained by the formation of a space charge layer near the interface of the solid-liquid heterojunction, which results in a built-in potential and makes the solid-liquid heterojunction work in photovoltaic mode.

A self-powered UV photodetector based on TiO2 nanorod arrays.

Large-area vertical rutile TiO2 nanorod arrays (TNAs) were grown on F/SnO2 conductive glass using a hydrothermal method at low temperature. A self-powered ultraviolet (UV) photodetector based on TiO2 nanorod/water solid-liquid heterojunction is designed and fabricated. These nanorods offer an enlarged TiO2/water contact area and a direct pathway for electron transport simultaneously. By connecting this UV photodetector to an ammeter, the intensity of UV light can be quantified using the output short-circuit photocurrent without a power source. A photosensitivity of 0.025 A/W and a quick response time were observed. At the same time, a high photosensitivity in a wide range of wavelength was also demonstrated. This TNA/water UV detector can be a particularly suitable candidate for practical applications for its high photosensitivity, fast response, excellent spectral selectivity, uncomplicated low-cost fabrication process, and environment-friendly feature.