Optogenetic Control of Voltage-Gated Calcium Channels

Voltage-gated Ca(2+) (CaV ) channels mediate Ca(2+) entry into excitable cells to regulate a myriad of cellular events following membrane depolarization. We report the engineering of RGK GTPases, a class of genetically encoded CaV channel modulators, to enable photo-tunable modulation of CaV channel activity in excitable mammalian cells. This optogenetic tool (designated optoRGK) tailored for CaV channels could find broad applications in interrogating a wide range of CaV -mediated physiological processes

A Robust Scheme to Detect SYN Flooding Attacks

Abstract—We propose a more robust scheme to detect SYN flooding attacks. Existing methods for detecting SYN flooding are based on the protocol behavior of TCP SYN–FIN (RST) or SYN–ACK pairs, as normally the number of SYN packets is equal to that of FIN (added with RST) packets, or ACK packets in the handshake. When SYN flood starts, there will be more SYN packets. However, the attacker can avoid the detection by sending the FIN or RST packets (ACK packets) in conjunction with the SYN packets. To make the detection scheme more robust, we record the flow information of SYN packets in a counting Bloom Filter, and count the FIN (RST) packets according to the Bloom Filter. In addition, the Change Point Detection method based on a non-parametric Cumulative Sum algorithm is applied to make the detection mechanism much more generally applicable. Through trace-driven simulations, we show our detection scheme is more efficient and robust in detecting various SYN flooding attacks. More importantly, our scheme can be easily deployed at ISP’s edge routers. I

Experiences with Active Per-Flow Queuing for Traffic Manager in High Performance Routers

Abstract—Per-flow queuing is believed to be an effective approach to guarantee Quality of Service (QoS) in high performance routers. However, its brute-force implementation consumes a huge amount of memory and is not scalable as the number of flows increases. Dynamic Queue Sharing (DQS) mechanism, in which a physical queue is dynamically created on-demand when a new flow comes and released when the flow temporarily paused, is able to achieve per-flow queuing performance with much less memory. In this paper, based on DQS, an active per-flow queuing system is designed, implemented and tested. To evaluate the effectiveness of DQS, we implement two FPGA-based Traffic Manager (TM) prototypes, one with DQS and the other a traditional one. The real chip implementation shows that DQS can not only scale down the required memory for per-flow queuing but also reduce the total number of control logic elements. As a result of reduced control logic, original 3-stage scheduling in naive scheme can be improved to be a single stage while maintaining the same delay performance, thus resulting in a faster speed potential. Besides, the power consumption can also considerably be reduced. Our experiments on a 4Gbps TM prototype using Stratix EP1S80F1508C5 FPGA show a 58.6% decrease in control memory. Meanwhile, the logic cells and LC registers are reduced by 6.8 % and 15.0 % respectively, and the power consumption is saved by 23 % compared with the bruteforce per-flow queuing implementation with 8K queues

The charge mobilities in fused ring Oligothiophenes and their derivatives: influence of molecular structures

Fused ring oligothiophenes and their derivatives, as active organic semiconductors, are widely used in electronic devices. The influence of molecular conjunction length on reorganization energy, electronic coupling and charge mobility of two fused ring oligothiophenes are investigated theoretically. The charge mobility of 2, 5-di(thiophen-2-yl)thieno [3, 2-b]thiophene (T - T-2 - T) with longer molecular conjunction length is 0.226 cm(2)V(-1)s(-1), which is nearly 3 times larger than that of 2, 2-bithieno[3, 2-b] thiophene (T-2 - T-2) as 0.085 cm(2)V(-1)s(-1). The investigation will provide a new perspective to design high mobility organic semiconductors

A retrospective study of immunoglobulin E as a biomarker for the diagnosis of acute ischemic stroke with carotid atherosclerotic plaques

Objective In this study, serum markers of acute ischemic stroke (AICS) with carotid artery plaque were retrospectively evaluated to establish a basis for discovering serological indicators for early warning of acute ischemic stroke (AICS). Methods A total of 248 patients with AICS were enrolled in Lanzhou University Second Hospital from January 2019 to December 2020. The study population included 136 males and 112 females, 64 ± 11 years of age. Of these, there were 90 patients with a transient ischemic attack (TIA), including 60 males and 30 females, aged 64 ± 8 years old. Patients with AICS were stratified by carotid ultrasound into a plaque group (n = 154) and a non-plaque group (n = 94). A total of 160 healthy subjects were selected as the control group. Serum lipoprotein-associated phospholipase A2 (Lp-PLA2), amyloid A (SAA), immunoglobulin E (IgE), D-dimer (D-D), total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) were collected from all subjects. Multivariate logistic regression was used to analyze the risk factors of AICS with carotid plaque. ROC curve was used to analyze the diagnostic efficacy of AICS with carotid plaque. Results The IgE, Lp-PLA2, SAA, LDL-C, TC, TG, and D-D levels in the AICS group were higher than those in the TIA group and healthy control group (P < 0.05). The IgE level was significantly higher than that in the healthy control group and TIA group. The IgE level in the AICS plaque group was significantly higher than that in the AICS non-plaque group (P < 0.01), and the Lp-PLA2 level was also different (P < 0.05). The incidence of AICS was positively correlated with Lp-PLA2, TC, IgE, TG, D-D, SAA and LDL-C (r = 0.611, 0.499, 0.478, 0.431, 0.386, 0.332, 0.280, all P < 0.05). The incidence of AICS with plaque was only positively correlated with IgE and Lp-PLA2 (r = 0.588, 0.246, P < 0.05). Logistic regression analysis showed that IgE and Lp-PLA2 were independent risk factors for predicting the occurrence of AICS with carotid plaque (P < 0.05). ROC curve analysis showed that the AUC of IgE (0.849) was significantly higher than other indicators; its sensitivity and specificity were also the highest, indicating that IgE can improve the diagnostic efficiency of AICS with carotid plaque. Conclusion IgE is a serum laboratory indicator used to diagnose AICS disease with carotid plaque, which lays a foundation for further research on potential early warning indicators of AICS disease

Direct Mechanism of the First Carbon-Carbon Bond Formation in the Methanol-to-Hydrocarbons Process

In the past two decades, the reaction mechanism of C-C bond formation from either methanol or dimethyl ether (DME) in the methanol-to-hydrocarbons (MTH) process has been a highly controversial issue. Described here is the first observation of a surface methyleneoxy analogue, originating from the surface-activated DME, by in situ solid-state NMR spectroscopy, a species crucial to the first C-C bond formation in the MTH process. New insights into the first C-C bond formation were provided, thus suggesting DME/methanol activation and direct C-C bond formation by an interesting synergetic mechanism, involving C-H bond breakage and C-C bond coupling during the initial methanol reaction within the chemical environment of the zeolite catalyst

Integration of morphology and electronic structure modulation on cobalt phosphide nanosheets to boost photocatalytic hydrogen evolution from ammonia borane hydrolysis

The controllable and safe hydrogen storage technologies are widely recognized as the main bottleneck for the accomplishment of sustainable hydrogen energy. Ammonia borane (AB) has regarded as a competitive candidate for chemical hydrogen storage. However, developing efficient yet high-performance catalysts towards hydrogen evolution from AB hydrolysis remains an enormous challenge. Herein, cobalt phosphide nanosheets are synthesized by a facile salt-assisted along with low-temperature phosphidation strategy for simultaneously modulating its morphology and electronic structure, and function as hydrogen evolution photocatalysts. Impressively, the Co2P nanosheets display extraordinary performance with a record high turnover frequency of 44.9 min−1, outperforming most of the noble-metal-free catalysts reported to date. This remarkable performance is attributed to its desired nanosheets structure, featuring with high specific surface area, abundant exposed active sites, and short charge diffusion paths. Our findings provide a novel strategy for regulating metal phosphides with desired phase structure and morphology for energy-related applications and beyond

Data-driven assisted real-time optimal control strategy of submerged arc furnace via intelligent energy terminals considering large-scale renewable energy utilization

Abstract This study presents a data-driven assisted real-time optimization model which is an innovative approach to address the challenges posed by integrating Submerged Arc Furnace (SAF) systems with renewable energy sources, specifically photovoltaic (PV) and wind power, with modern intelligent energy terminals. Specifically, the proposed method is divided into two stages. The first stage is related to data-driven prediction for addressing local time-varying renewable energy and electricity market prices with predicted information, and the second stage uses an optimization model for real-time SAF dispatch. Connections between intelligent energy terminals, demand-side devices, and load management systems are established to enhance local renewable resource utilization. Additionally, mathematical formulations of the operating resistance in SAF are explored, and deep neuron networks are employed and modified for dynamic uncertainty prediction. The proposed approach is validated through a case study involving an intelligent energy terminal with a 12.5 MVA SAF system and 12 MW capacity renewable generators in an electricity market with fluctuating prices. The findings of this research underscore the efficacy of the proposed optimization model in reducing operational costs and enhancing the utilization of localized renewable energy generation. By integrating four distinct dissatisfaction coefficients into the optimization framework, we demonstrate the model's adaptability and efficiency. The application of the optimization strategy delineated herein results in the SAF system's profitability oscillating between $111 and$416 across various time intervals, contingent upon the coefficient settings. Remarkably, an aggregate daily loss recovery amounting to $1,906.84 can be realized during the optimization period. Such outcomes not only signify considerable economic advantages but also contribute to grid stability and the diminution of renewable energy curtailment, thereby underscoring the dual benefits of economic efficiency and sustainability in energy management practices

Methanol to Olefins Reaction Route Based on Methylcyclopentadienes as Critical Intermediates

Starting from C1 raw material, methanol conversion to hydrocarbons has been realized via a rather complicated pathway. In this contribution, we proposed an alternative methanol reaction route and provided a general understanding of such complex indirect mechanism. The methylcyclopentenyl cations and their deprotonated counterparts (methylcyclopentadienes) were validated to appear on the working H-SAPO-34 catalyst by in situ C-13 MAS NMR spectroscopy and the GC-MS technique, and their catalytic reactivity was revealed by the C-12/C-13-CH3OH isotopic switch experiment. In this context, a cyclopentadienes-based cycle was established, in which light olefins were formed with methylcyclopentadienes as critical intermediates. The feasibility of this alternative route was confirmed by density functional theory calculations. Notably, the cyclopentadienes-based cycle runs in parallel with the traditional alkenes-based and aromatics-based cycles; these three mechanistic cycles are interrelated through interconversion of the involved intermediates, including alkene, cyclopentadiene, and aromatic species. All these three cycles work together for the C-C bond assembly in the methanol-to-olefins reaction system. These findings help to build a more complete methanol conversion network and advance the in-depth understanding of indirect mechanism of methanol conversion

Influences of the confinement effect and acid strength of zeolite on the mechanisms of Methanol-to-Olefins conversion over H-ZSM-5: A theoretical study of alkenes-based cycle

Methanol-to-Olefins (MTO) conversion over acidic zeolite catalysts has become the most important non petrochemical route for the production of light olefins. The 'dual-cycle' mechanism (i.e., alkenes-based cycle and aromatics-based cycle) over H-ZSM-5 zeolite has been generally accepted for olefins generation from methanol conversion. However, the relationship between the catalytic performance and the confinement effect/acid strength of the catalyst is still unclear. Herein, the methylation, isomerization and cracking processes involved in the alkenes-based cycle are discussed in-depth by density functional theory (DFT) calculations. The calculation results predicted that the transition states can be considerably stabilized by the van der Waals (vdW) interactions from the zeolite framework, resulting in the reduction of the activation barriers. And acid strength can also enhance the reaction activities. However, the catalytic reactivity of all elementary steps in the alkenes-based cycle can be improved at a different degree with increasing the acid strength. In addition, the ethene formation, transformation and the precursor of ethene formation need higher energy. And increasing acid strength can sharply decrease the activation barriers of ethene formation of cracking reaction, indicating that ethene formation may need strong acid strength. (C) 2016 Elsevier Inc. All rights reserved