Ultra-Broadband and Low-Loss Silicon-Based Power Splitter Based on Subwavelength Grating-Assisted Multimode Interference Structure

High-performance and compact power splitters are fundamental components in on-chip photonic integrated circuits (PICs). We propose a silicon-based power splitter based on a subwavelength grating (SWG)-assisted multimode interference (MMI) structure. To shorten the device size and enhance the device performance, an inverse-tapered SWG is embedded in the central region of the MMI and two rows of uniform SWG are embedded on both sides, together with two right-angled cutting structures on the input side. According to the results, the MMI length was obviously reduced to 3.2 μm (5.2 μm for conventional MMI structure under the same waveguide width), while the insertion loss (IL) and reflection loss were 0.08 dB and <−35 dB, respectively. Moreover, the allowable working bandwidth could be extended to 560 nm by keeping IL <0.6 dB, covering the whole optical communication band. On the basis of these features, we believe that such a power splitter is very promising for building on-chip large-scale PICs where power splitting is indispensable

Design of Compact, Broadband, and Low-Loss Silicon Waveguide Bends with Radius under 500 nm

Waveguide bend is an indispensable component in the on-chip compact photonic integrated circuits (PICs) and the minimum bend size greatly limits the increase of integration density of PICs. Here, we propose broadband and low-loss silicon waveguide bend schemes using air trenches on both sides and embedded germanium arc in the inner side of waveguide bend. Using these ways, the silicon waveguide bending radius can be greatly reduced to less than 500 nm and the obtained insertion loss (IL) can be as low as 0.12 dB compared with IL = 1.73 dB obtained by direct silicon waveguide bend under the same bending radius. Meanwhile, the working bandwidth can be extended over 500 nm covering the whole optical communication band by keeping IL < 0.5 dB. Therefore, the proposed device schemes could push the development of on-chip PICs toward higher integration density

Design of Compact, Broadband, and Low-Loss Silicon Waveguide Bends with Radius under 500 nm

Waveguide bend is an indispensable component in the on-chip compact photonic integrated circuits (PICs) and the minimum bend size greatly limits the increase of integration density of PICs. Here, we propose broadband and low-loss silicon waveguide bend schemes using air trenches on both sides and embedded germanium arc in the inner side of waveguide bend. Using these ways, the silicon waveguide bending radius can be greatly reduced to less than 500 nm and the obtained insertion loss (IL) can be as low as 0.12 dB compared with IL = 1.73 dB obtained by direct silicon waveguide bend under the same bending radius. Meanwhile, the working bandwidth can be extended over 500 nm covering the whole optical communication band by keeping IL &lt; 0.5 dB. Therefore, the proposed device schemes could push the development of on-chip PICs toward higher integration density

Ultra-Broadband and Low-Loss Silicon-Based Power Splitter Based on Subwavelength Grating-Assisted Multimode Interference Structure

High-performance and compact power splitters are fundamental components in on-chip photonic integrated circuits (PICs). We propose a silicon-based power splitter based on a subwavelength grating (SWG)-assisted multimode interference (MMI) structure. To shorten the device size and enhance the device performance, an inverse-tapered SWG is embedded in the central region of the MMI and two rows of uniform SWG are embedded on both sides, together with two right-angled cutting structures on the input side. According to the results, the MMI length was obviously reduced to 3.2 &mu;m (5.2 &mu;m for conventional MMI structure under the same waveguide width), while the insertion loss (IL) and reflection loss were 0.08 dB and &lt;&minus;35 dB, respectively. Moreover, the allowable working bandwidth could be extended to 560 nm by keeping IL &lt;0.6 dB, covering the whole optical communication band. On the basis of these features, we believe that such a power splitter is very promising for building on-chip large-scale PICs where power splitting is indispensable

MDGN: Circuit design of memristor‐based denoising autoencoder and gated recurrent unit network for lithium‐ion battery state of charge estimation

Abstract Due to the highly complex and non‐linear physical dynamics of lithium‐ion batteries, it is unfeasible to measure the state of charge (SOC) directly. Designing systems capable of accurate SOC estimation has become a key technology for battery management systems (BMS). Existing mainstream SOC estimation approaches still suffer from the limitations of low efficiency and high‐power consumption, owing to the great number of samples required for training. To address these gaps, this paper proposes a memristor‐based denoising autoencoder and gated recurrent unit network (MDGN) for fast and accurate SOC estimation of lithium‐ion batteries. Specifically, the DAE circuit module is designed to extract useful feature representation with strong generalization and noise immunity. Then, the gated recurrent unit (GRU) circuit module is designed to learn the long‐term dependencies between high‐dimensional input and output data. The overall performance is evaluated by root mean square error (RMSE) and mean absolute error (MAE) at 0, 25, and 45°C, respectively. Compared with the current state‐of‐the‐art methods, the entire scheme shows its superior performance in accuracy, robustness, and operation cost (referring to time cost)

The Sources of Sedimentary Organic Matter Traced by Carbon and Nitrogen Isotopes and Environmental Effects during the Past 60 Years in a Shallow Steppe Lake in Northern China

The organic matter of lake sediment plays an important role in paleolimnological reconstruction. Here, we report a detailed study of organic matter components (Corg%, N%, δ13C, δ15N) in a dated sediment core of Hulun Lake in northern China. Multiple mixing models based on the stoichiometric ratios and stable isotopic compositions were applied to quantify the contributions of organic matter sources in lake sediment. The results show that the organic matter in the sediments from Hulun Lake mainly comes from terrestrial organic matter: the proportion of terrestrial organic matter is more than 80%. The results of the SIAR mixing model further reveal that the proportions of terrestrial C3 plants-derived organic matter, soil organic matter, and lake plankton-derived organic matter were 76.0%, 13.9%, and 10.1%, respectively. The organic matter content of lake sediment from terrestrial sources began to increase significantly from 1980 onward, which is consistent with the growth in overgrazing in the Hulun Lake basin. The content of organic matter from endogenous lake-derived sources began to increase significantly after 2000 due to the nutrients gradually becoming concentrated in lake water, indicating that the reduction in rivers’ discharge and the downgrade of the lake water level were the immediate causes of the lake’s environmental deterioration during this period

Neuroprotective Effects of Ginsenosides against Cerebral Ischemia

Ginseng has been used worldwide as traditional medicine for thousands of years, and ginsenosides have been proved to be the main active components for their various pharmacological activities. Based on their structures, ginsenosides can be divided into ginseng diol-type A and ginseng triol-type B with different pharmacological effects. In this study, six ginsenosides, namely ginsenoside Rb1, Rh2, Rg3, Rg5 as diol-type ginseng saponins, and Rg1 and Re as triol-type ginseng saponins, which were reported to be effective for ischemia-reperfusion (I/R) treatment, were chosen to compare their protective effects on cerebral I/R injury, and their mechanisms were studied by in vitro and in vivo experiments. It was found that all ginsenosides could reduce reactive oxygen species (ROS), inhibit apoptosis and increase mitochondrial membrane potential in cobalt chloride-induced (CoCl2-induced) PC12 cells injury model, and they could reduce cerebral infarction volume, brain neurological dysfunction of I/R rats in vivo. The results of immunohistochemistry and western blot showed that the expression of Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88), silencing information regulator (SIRT1) and nuclear transcription factor P65 (NF-&#954;B) in hippocampal CA1 region of some ginsenoside groups were also reduced. In general, the effect on cerebral ischemia of Rb1 and Rg3 was significantly improved compared with the control group, and was the strongest among all the ginsenosides. The effect on SIRT1 activation of ginsenoside Rb1 and the inhibition effect of TLR4/MyD88 protein expression of ginsenoside Rb1 and Rg3 were significantly stronger than that of other groups. The results indicated that ginsenoside Rg1, Rb1, Rh2, Rg3, Rg5 and Re were effective in protecting the brain against ischemic injury, and ginsenoside Rb1 and Rg3 have the strongest therapeutic activities in all the tested ginsenosides. Their neuroprotective mechanism is associated with TLR4/MyD88 and SIRT1 activation signaling pathways, and they can reduce cerebral ischemic injury by inhibiting NF-&#954;B transcriptional activity and the expression of proinflammatory cytokines, including interleukin-1&#946; (IL-1&#946;), tumor necrosis factor-&#945; (TNF-&#945;) and interleukin-6 (IL-6)

Programming of mouse obesity by maternal exposure to concentrated ambient fine particles

Abstract Background Many diseases including obesity may originate through alterations in the early-life environment that interrupts fetal development. Increasing evidence has shown that exposure to ambient fine particles (PM2.5) is associated with abnormal fetal development. However, its long-term metabolic effects on offspring have not been systematically investigated. Results To determine if maternal exposure to PM2.5 programs offspring obesity, female C57Bl/6j mice were exposed to filtered air (FA) or concentrated ambient PM2.5 (CAP) during pre-conception, pregnancy, and lactation, and the developmental and metabolic responses of offspring were assessed. The growth trajectory of offspring revealed that maternal exposure to CAP significantly decreased offspring birth weight but increased body weight of adult male but not female offspring, and the latter was expressed as increased adiposity. These adult male offspring had increased food intake, but were sensitive to exogenous leptin. Their hypothalamic expression of Socs3 and Pomc, two target genes of leptin, was not changed, and the hypothalamic expression of NPY, an orexigenic peptide that is inhibited by leptin, was significantly increased. These decreases in central anorexigenic signaling were accompanied by reduced plasma leptin and its expression in adipose tissues, the primary source of circulating leptin. In contrast, maternal exposure did not significantly change any of these indexes in adult female offspring. Pyrosequencing demonstrated that the leptin promoter methylation of adipocytes was significantly increased in CAP-exposed male but not female offspring. Conclusions Our data indicate that maternal exposure to ambient PM2.5 programs obesity in male offspring probably through alterations in the methylation of the promoter region of the leptin gene

Additional file 1: Table S1. of Programming of mouse obesity by maternal exposure to concentrated ambient fine particles

Primer sequences for real-time RT-PCR. Table S2 Primer sequences for leptin promoter methylation assessments. (PDF 123 kb