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Dopamine (DA) is a widely present, calcium cholinergic neurotransmitter in the body, playing important roles in the central nervous system and cardiovascular system. Developing fast and sensitive DA detection methods is of great significance. Fluorescence-based methods have attracted much attention due to their advantages of easy operation, a fast response speed, and high sensitivity. This study prepared hydrophilic and high-performance CdS/ZnS quantum dots (QDs) for DA detection. The waterborne CdS/ZnS QDs were synthesized in one step using the amphiphilic polymer PEI-g-C14, obtained by grafting tetradecane (C14) to polyethyleneimine (PEI), as a template. The polyacrylonitrile nanofiber membrane (PAN-NFM) was prepared by electrospinning (e-spinning), and a metal organic frame (ZIF-8) was deposited in situ on the surface of the PAN-NFM. The CdS/ZnS QDs were loaded onto this substrate (ZIF-8@PAN-NFM). The results showed that after the deposition of ZIF-8, the water contact angle of the hydrophobic PAN-NFM decreased to within 40°. The nanofiber membrane loaded with QDs also exhibited significant changes in fluorescence in the presence of DA at different concentrations, which could be applied as a fast detection method of DA with high sensitivity. Meanwhile, the fluorescence on this PAN-NFM could be visually observed as it transitioned from a blue-green color to colorless, making it suitable for the real-time detection of DA. [ABSTRACT FROM AUTHOR]

Correlation-based detection techniques are widely used in the weak periodic signal detection field. Traditionally, they are based on extracting the correlation of a weak signal from noise. Considering the impact of a weak signal on the randomness of background noise, this article takes the opposite approach and proposes a weak signal detection technique based on the Durbin–Watson (DW) test and one-bit sampling, detecting the weak signal due to the extent to which the randomness of noise is affected. The randomness of noise is analyzed through the DW test, which is a method for detecting the randomness of data sequences through first-order autocorrelation. One-bit sampling is adopted to reduce the complexity of the sampling circuit and data processing algorithm. The effectiveness of the DW test in the situation of one-bit sampling is demonstrated through simulation and analysis. Simulation results show that the proposed technique is capable of detecting weak sinusoidal and square-wave signals with a signal-to-noise ratio (SNR) above −30 dB, and the frequency or SNR of a weak signal can be further estimated based on mutual constraints. The measured results confirm the capability. In addition, the factors of coherent sampling, noise bandwidth, and comparator threshold that influence the performance of the proposed technique are simulated and discussed in detail. [ABSTRACT FROM AUTHOR]

The aerial parts of Mosla chinensis Maxim. and Mosla chinensis cv. 'Jiangxiangru' (MCJ) are widely utilized in traditional Chinese medicine (TCM), known collectively as Xiang-ru. However, due to clinical effectiveness concerns and frequent misidentification, the original plants have increasingly been substituted by various species within the genera Elsholtzia and Mosla. The challenge in distinguishing between these genera arises from their similar morphological and metabolic profiles. To address this issue, our study introduced a rapid method for metabolic characterization, employing high-resolution mass spectrometry-based metabolomics. Through detailed biosynthetic and chemometric analyses, we pinpointed five phenolic compounds—salviaflaside, cynaroside, scutellarein-7- O -D-glucoside, rutin, and vicenin-2—among 203 identified compounds, as reliable chemical markers for distinguishing Xiang-ru from closely related Elsholtzia species. This methodology holds promise for broad application in the analysis of plant aerial parts, especially in verifying the authenticity of aromatic traditional medicinal plants. Our findings underscore the importance of non-volatile compounds as dependable chemical markers in the authentication process of aromatic traditional medicinal plants. [ABSTRACT FROM AUTHOR]

Salvia apiana (S. apiana) Jepson is a medicinal plant that is frequently used by the Chumash Indians in southern California as a diaphoretic, calmative, diuretic, or antimicrobial agent. Abietane-type diterpenoids (ATDs) and phenolic acids (PAs) are the main bioactive ingredients in S. apiana. However, few studies have looked into the biosynthesis of ATDs and PAs in S. apiana. In this study, using metabolic profiling focused on the ATDs and PAs in the roots and leaves of S. apiana , we found a distinctive metabolic feature with all-around accumulation of ATDs, but absence of salvianolic acid B. To identify the candidate genes involved in these biosynthesis pathways, full-length transcriptome was performed by PacBio single-molecule real-time (SMRT) sequencing. A total of 50 and 40 unigenes were predicted to be involved in ATDs and PAs biosynthesis, respectively. Further transcriptional profile using Illumina HiSeq sequencing showed that the transcriptional variations of these pathways were consistent with the accumulation patterns of corresponding metabolites. A plant kingdom-wide phylogenetic analysis of cytochromes (CYPs) identified two CYP76AK and two CYP76AH subfamily genes that might contribute for the specific ATDs biosynthesis in S. apiana. We also noticed that the clade VII laccase gene family was significantly expanded in Salvia miltiorrhiza compared with that of S. apiana , indicating their involvements in the formation of salvianolic acid B. In conclusion, our results will enable the further understanding of ATDs and PAs biosynthesis in S. apiana and Salvia genus. [ABSTRACT FROM AUTHOR]

In this letter, a vertically polarized 360° azimuth scanning phased array based on a wide beamwidth element is proposed. The proposed array consists of two back-to-back linear arrays. The broadside and endfire scanning modes are combined to realize 360° beam scanning in the azimuth plane (H-plane). A 2 × 8 array working at 3 GHz has been fabricated and measured. The array scans from −180° to 180° in the H-plane with the measured peak gain of 10.8 dBi, the measured gain fluctuation less than 2 dB. The total height of the proposed array is 0.32 λ, showing its potentials in aircraft-based application. [ABSTRACT FROM AUTHOR]

This article presents a co-linearly polarized (LP) stacked two-port antenna with compact size and broadside radiation patterns for in-band full-duplex (IBFD) application. The proposed IBFD antenna consists of a patch antenna and a substrate integrated waveguide (SIW) cavity-backed slot antenna (CBSA). The patch antenna and the CBSA are used as the transmitter (Tx) and receiver (Rx), respectively. The Rx is placed above the Tx for compact size. Linear polarization and broadside radiation patterns are achieved in this article. A cavity-patch coupling (CPC) path is added for canceling the slot-patch coupling (SPC) by using four probes to connect the top layer of the SIW cavity and the metal ground. Parametric studies show that the two coupling paths can be adjusted independently. Experimental results illustrate that the measured highest isolation over 40 dB is obtained with a compact size of $30\times 30\times {4}$ mm3 ($0.63\lambda _{0} \times 0.63\lambda _{0} \times 0.08\lambda _{0}$ , $\lambda _{0}$ is the free-space wavelength at the center frequency of about 6.29 GHz). The measured −10 dB bandwidths of the Tx and Rx antennas are 430 and 100 MHz, respectively. The proposed stacked IBFD antenna is validated with the merits of identical polarization, same radiation direction, and compact size. [ABSTRACT FROM AUTHOR]

In this article, a compact co-polarized decoupled antenna for full-duplex application working at 1.71 GHz is proposed. The antenna is composed of two back-to-back air-dielectric planar inverted-F antennas (PIFAs) with zero edge-to-edge distance. The whole system is included in a compact volume of $0.45\lambda _{\mathrm {\mathbf {0}}} \times 0.45\lambda _{\mathbf {0}} \times 0.02\lambda _{\mathbf {0}}$. The proposed antenna is designed based on the common mode (CM)/differential mode (DM) cancellation theory and its design guideline is illustrated in detail. Isolation maximum of 42 dB, broadside gain of 6.7 dB, and efficiency of 90% have been achieved in the proposed structure. There is a 1.9 dB gain difference between the broadside gain and the maximum gain. The proposed antenna shows its potentials in the radio frequency front-end incorporate design. [ABSTRACT FROM AUTHOR]

This paper proposes a new feeding topology with internal 180° phase reversal for wideband series‐fed slot array antennas. As a demonstration, a serial fed, half‐wavelength separated, 7‐element array is designed at 5.8 GHz. Comparing with conventional series‐fed arrays, which require one‐wavelength separation, the phase difference between adjacent elements varies less with frequency. Thus, the proposed array has more stable beam pointing and wider 1 dB gain bandwidth. A prototype was fabricated and measured to validate the performance of the feeding topology. A wide operating bandwidth of 22.4% for S11 < −10 dB, a 1 dB gain bandwidth of 14% and bi‐directional peak gain of 10.01 dBi are achieved with the array length of 2.7λ0. The proposed feeding topology shows its potentials in realizing signal coverage on some special occasions, such as coal mines and tunnels. [ABSTRACT FROM AUTHOR]

In this letter, a novel reconfigurable 0°/90° phase shifter is proposed. Compared with the conventional phase shifters, the proposed one uses fewer reconfigurable devices and becomes more compact. Two states of a meander line are used to generate the 90° phase shift, making it suitable for the 2-D beam steering 2-bit array application. A phase shifter prototype on F4B was measured to validate its design theory. Four phase states (i.e., 0°, 90°, 180°, and 270°) are realized through the combination of the phase shifter and the array radiation element. A 2 × 4 array working at 1.5 GHz was fabricated and measured to verify the performance of the proposed phase shifter. When different phase states are switched, the measured peak gain of the array varies from 10.6 to 11.2 dBi. [ABSTRACT FROM AUTHOR]

The detection of a high repetition rate weak signal is studied in this paper. Owing to the characteristics of the signal of interest, both high speed analog-to-digital converter (ADC) and low computational complexity data processing techniques are required for high speed real-time weak signal detection. In this paper, a novel field programmable gate array (FPGA) based high speed real-time periodic weak signal detection technique is presented. Cascaded comparators outside the FPGA and cascaded flip flops in the FPGA are used to implement a one-bit ADC, which performs quantization first followed by sampling. Based on this novel design, a time-interleaved structure with several sub-channels is further proposed to significantly improve the sampling rate of the one-bit ADC, which does not require calibration for offset, gain, and sample-time mismatches between sub-channels. Each sub-channel has a long-time coherent integration structure to coherently integrate the sampled one-bit data. A full layer clearance mechanism that only operates on specific bits of the integrated sums is proposed to overcome the influence of a noise baseline drift on the weak signal detection. Compared with the traditional adaptive threshold, this mechanism has a significantly lower computational complexity. A prototype with three sub-channels performing 1.5 Gs/s sampling is implemented to verify the proposed technique. The results obtained confirm its high sampling rate and noise baseline drift tolerance in weak signal detection. [ABSTRACT FROM AUTHOR]

Herein, we developed an enantioselective addition of aliphatic aldehydes to 2-hydroxychalcone promoted by cooperative organocatalysts, giving access to hybrid flavonoids in excellent enantioselectivities. This reaction took advantage of cycloisomerization of 2-hydroxychalcone to form a transient flavylium under the irradiation of 24 W CFL, which was trapped by the in situ generated chiral enamine intermediate. The synergistic action of chiral phosphoric acid secured the excellent outcome of this reaction by ion-pairing with the transient flavylium. [ABSTRACT FROM AUTHOR]

In this communication, a millimeter-wave (mm-wave) air-filled slot antenna with a conical beam at 60 GHz is proposed. The antenna is suitable to be integrated with various IC systems mainly because it is designed and fabricated based on bulk silicon microelectromechanical systems (MEMS) technology. The whole structure is composed of an antenna part and a waveguide to substrate integrated waveguide (SIW) converter. In the antenna part, four meander slots are arranged annularly and excited by a square air cavity. The conical radiation pattern benefits from the out-phase ${E}$ -field excited on slots. An operating bandwidth of 2.17% for S11 < −10 dB and a conical beam peak gain of 3.21 dBi are achieved. The proposed antenna shows its potentials in mm-wave indoor communication. [ABSTRACT FROM AUTHOR]

We investigate THz absorption characteristics of graphene cavity-based electromagnetic metamaterial structures by using the conductivity characteristic matrix method. We demonstrate that the proposed structure can obtain ideal terahertz absorption due to the strong localization of photons in the defect layer of the electromagnetic metamaterial structure. The THz absorption can be continuously adjusted from 0% to 100% by controlling the chemical potential of graphene through a gate voltage. The maximum THz absorption value can be tailored by adjusting the incident angle or the period number of the two PCs with respect to the graphene layer. The position of the THz absorption peak can be adjusted by changing the thickness ratio of the layers constituting the electromagnetic metamaterial structure. Our proposal may have potentially important applications in photodetectors, saturable absorbers, and photovoltaics. [ABSTRACT FROM AUTHOR]

A 256-channel time-of-flight electronics system has been developed for a facility called “Back-n white neutron source (WNS)” in China Spallation Neutron Source (CSNS). This paper presents the structure and performance of the electronics system and test results at CSNS-WNS. A piece of lithium glass scintillator, coupled with a 256-channel multi-anode photomultiplier tube, is placed at the center of the neutron beam line as the detector. A 256-channel readout electronics system, including one front-end board (FEB), four time-to-digital converter (TDC) cards and one clock distribution module (CDM), measures the arrival time of each signal from the detector. Signals are sent to FEB from the detector through 15-cm cables and discriminated on FEB. FEB drives differential signals over 2-m cables to the TDC cards. Each TDC card has 64 channels, using a field-programmable gate array (FPGA) to measure the arrival time of each signal. The CDM supplies clock signals to the TDC cards to make them work synchronously. The TDC cards and CDM are housed in one peripheral component interconnect (PCI) eXtensions for Instrumentation chassis. The TDC cards achieve a timing precision of 3.5 ns. The electronics system meets the requirement of the experiment and is currently being used in CSNS. [ABSTRACT FROM AUTHOR]

In this letter, a monostatic and cochannel simultaneous transmit and receive (STAR) antenna with identical circularly polarized radiations of transmitting (TX) and receiving (RX) channels is designed using a thin single-layer substrate. Four concentrically arranged microstrip radiating elements are properly excited by two sets of feeding networks: the feeding network of transmitting antenna (FNT) and the feeding network of receiving antenna (FNR). To fit FNT and FNR into the same plane, the FNR consists of a compact sequential-phase structure placed at the center of the antenna, while the FNT is aligned along the side with a planar crossover junction armed. Two vital techniques, orthogonal feeding points and leakage signal cancellation based on feeding networks, are utilized for satisfactory isolation level between the TX and RX ports. The experiment results demonstrate an isolation at least 41 dB and up to 54 dB, an axial ratio better than 1.7 dB, and a realized gain of 7.2 ∼ 10.5 dBic in the 2.4 GHz WLAN band. Our design scheme may overcome the profile and cost limitations of bulky multilayered STAR antennas, and thus portends potential for the highly integrated inband duplex systems. [ABSTRACT FROM AUTHOR]

High sampling speed can be achieved using multiple analog-to-digital converters (ADCs) based on the time-interleaved analog-to-digital conversion (TIADC) technique. Various types of methods were proposed to correct the mismatch errors among parallel ADC channels in TIADC systems, which would deteriorate the system performance. Traditional correction methods based on digital signal processing have good performance, however, often only for input signals limited in a narrow frequency band. In this paper, we present our recent work on the design of an 8-Gs/s 12-bit TIADC system and the implementation of real-time mismatch correction algorithms in field programmable gate array devices, over a broadband of input signal frequencies. Tests were also conducted to evaluate the system performance, and the results indicate that the effective number of bits is enhanced to be better than 8.5 bits (<800 MHz) and 8 bits from 800 MHz to 1.6 GHz after correction, almost the same with that of the ADC chip employed. [ABSTRACT FROM AUTHOR]

Abstract: A highly enantioselective tandem Michael addition of tryptamine‐derived oxindoles to alkynones was developed by taking advantage of a chiral N,N′‐dioxide Sc(OTf)3 catalyst. The reaction enables the facile preparation of enantioenriched spiro[pyrrolidine‐3,3′‐oxindole] compounds, which provides a novel strategy for the synthesis of monoterpenoid indole alkaloids. As a demonstration, the asymmetric synthesis of strychnos alkaloids [(−)‐tubifoline, (−)‐tubifolidine, (−)‐dehydrotubifoline] was achieved in 10–11 steps. [ABSTRACT FROM AUTHOR]

An efficient approach for the synthesis of 2,2-disubstituted indolin-3-ones is described. From readily accessible aryl hydrazines and allyloxyketones, 2,2-disubstituted indolin-3-ones could be obtained in good to excellent yields under mild reaction conditions via a cascade Fischer indolization/Claisen rearrangement process. This protocol provides a facile entry to 2,2-disubstituted indolin-3-ones, which have been applied in the construction of the benzofuroindoline framework related to Phalarine. [ABSTRACT FROM AUTHOR]

Oxidative ring contraction of cyclic α-formyl ketones was facilitated by the action of H2O2 under operationally simple and environmentally benign reaction conditions. The process was highly regioselective and enables stereospecific construction of contiguous quaternary all-carbon centers from stereodefined all-substituted all-cyclic ketones. The asymmetric syntheses of (+)-cuparene and (+)-tochuinyl acetate were also successively achieved by taking advantage of this novel protocol. [ABSTRACT FROM AUTHOR]

Abkürzung: Eine enantioselektive Bromcyclisierung von Tryptamin unter Verwendung eines anionischen chiralen Phasentransferkatalysators führt direkt zu chiralen 3 ‐ Brompyrroloindolinen. Die Reaktion ermöglicht eine vierstufige enantioselektive Synthese von (−) ‐ Chimonanthin. PG=Schutzgruppe. [ABSTRACT FROM AUTHOR]

An efficient method for the asymmetric bromo-oxycyclization of a broad range of (2-alkenyl)phenylsilanols is described which provides benzoxazoles with a quarternary carbon centre in generally high yields and with high enantiomeric purity. [ABSTRACT FROM AUTHOR]

Objective: The present study aimed to investigate the molecular mechanism through which Perilla essential oil treats acute lung injury (ALI) through network pharmacology, molecular docking, and in vitro assays., Methods: Relevant ALI targets of the active ingredients of Perilla essential oil were predicted using the SwissTargetPrediction database and meta TarFisher database. These ALI targets were then screened using GeneCards and DisGeNET, and differentially expressed ALI target genes were identified using the Gene Expression Omnibus (GEO) database. Next, key targets were enriched using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Protein-protein interaction network analysis was performed to obtain targets with the highest degree values for molecular docking with Perilla essential oil active ingredients. For in vitro experiments, lipopolysaccharide (LPS) was used to induce an ALI inflammation model using RAW264.7 cells. The model cells were then treated with Perilla essential oil to detect the protein expression levels of vascular endothelial factor (NO), tumor necrosis factor (TNF-α), and p65 nuclear transcription factor in them., Results: Sixty-eight key targets of Perilla oil were identified for the treatment of ALI. These targets were found to be involved in biological processes related to peptides, response to lipopolysaccharides, the positive regulation of cytokine production, etc., using GO. The signaling pathways found to be associated with the targets included the AGE-RAGE signaling pathway in diabetic complications, the NF-kappa B signaling pathway, and small cell lung cancer and other inflammatory signaling pathways. The five key targets that showed good binding activity with Perilla oil active ingredients included TNF, RELA, PARP1, PTGS2, and IRAK4. In vitro assays showed that Perilla essential oil could significantly reduce NO and TNF-α levels and inhibit the phosphorylation of nuclear transcription factor P65, thus inhibiting the activation of NF-κB signaling pathway. Conclusion Perilla essential oil can play a role in the treatment of ALI by inhibiting the activation of the NF-κB signaling pathway and preventing an excessive inflammatory response. This study thus provides a reference for the in-depth study of the mechanisms through which Perilla essential oil treats ALI., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Remote sensing of atmospheric refractive index structure constant ($\boldsymbol{C}&#95;{\boldsymbol{n}}^2$) using lidar incorporating a single-photon detector (SPD) is proposed. The influence of turbulence on the fiber coupling efficiency with different fiber modes is analyzed. $\boldsymbol{C}&#95;{\boldsymbol{n}}^2$ can be derived from the ratio of the backscattering signals counted on single-mode and multimode fiber-coupling channels of the SPD. In the experiment, by eliminating the shot noise effect on the fluctuation of the ratio, the lowest coupling ratio is used to retrieve $\boldsymbol{C}&#95;{\boldsymbol{n}}^2$ and demonstrated by comparing to the results measured from a large aperture scintillometer (LAS). Good agreement between results from the LAS and the lidar is achieved. The correlation coefficients are 0.90, 0.89, and 0.89, under three different weather conditions.

Relying on the nucleophilicity of silanol for building up silicon-incorporated scaffold with an enantiopure tetrasubstituted carbon center remains elusive. In this report, asymmetric bromo-oxycyclization of olefinic silanol by using chiral anionic phase-transfer catalyst is described. This protocol provided a facile entry to a wide arrangement of enantiopure benzoxasilole in moderate to excellent enantioselectivities depending on the unique reactivity of bromine/N-benzyl-DABCO complex.

The first enantioselective synthesis of (-)-conolutinine was achieved in 10 steps. The synthesis featured a catalytic asymmetric bromocyclization of tryptamine to forge the tricycle intermediate. Hydration of an alkene catalyzed by Co(acac)2 was also employed as a key step to diastereoselectively introduce the tertiary alcohol moiety. The absolute configuration of (-)-conolutinine was established to be (2S,5aS,8aS,13aR) based on this asymmetric total synthesis.

A shorter path: A highly enantioselective bromocyclization of tryptamine has been developed using an anionic chiral phase-transfer catalyst. This method provides a direct approach for preparing chiral 3-bromopyrroloindoline from tryptamine, which enables a four-step enantioselective synthesis of (-)-chimonanthine. PG=protecting group., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)