Optical readout of charge carriers stored in a 2D memory cell of monolayer WSe2.

Owing to their superior charge retaining and transport characteristics, 2D transition metal dichalcogenides are investigated for practical applications in various memory-cell structures. Herein, we fabricated a quasi-one-terminal 2D memory cell by partially depositing a WSe2 monolayer on an Au electrode, which can be manipulated to achieve efficient charge injection upon the application or removal of external bias. Furthermore, the amount of charge carriers stored in the memory cell could be optically probed because of its close correlation with the fluorescence efficiency of WSe2, allowing us to achieve an electron retention time of ∼300 s at the cryogenic temperature of 4 K. Accordingly, the simplified device structure and the non-contact optical readout of the stored charge carriers present new research opportunities for 2D memory cells in terms of both fundamental mechanism studies and practical development for integrated nanophotonic devices.

ASE noise mitigation with digital frequency offset loading for discrete spectrum nonlinear frequency division multiplexing systems.

We propose an amplified spontaneous emission (ASE) noise mitigation scheme utilizing digital frequency offset loading (DFO-loading) for discrete spectrum nonlinear frequency division multiplexing (DS-NFDM) systems. Firstly, based on the one-to-one mapping relationship between frequency offsets and eigenvalue positions, the transmitter side encodes 4-bit information onto 16 kinds of different digital frequency offsets. Then, a sliding window-assisted eigenvalue position (SWA-EP) decoding technology is further proposed to substitute the classical channel equalization and carrier phase recovery processes, with the purpose of recovering the original information. The numerical and experimental results demonstrate that, compared with b-coefficient 16 quadrature amplitude modulation (QAM) scheme, Q-factor gains are 2.1 dB under 15 dB optical signal-to-noise ratio (OSNR) and 1.8 dB after 800 km fiber transmission, respectively. Moreover, its complexity is only 0.6% of the b-coefficient scheme. The DFO-loading scheme offers an effective and low-complexity way to mitigate ASE noise of DS-NFDM system.

Micrometer-Scale Carrier Transport in the Solid Film of Giant CdSe/CdS Nanocrystals Imaged by Transient Absorption Microscopy.

For the practical applications in solar cells and photodetectors, semiconductor colloidal nanocrystals (NCs) are assembled into a high-concentration film with carrier transport characteristics, the full understanding and effective control of which are critical for the achievement of high light-to-electricity conversion efficiencies. Here we have applied transient absorption microscopy to the solid film of giant CdSe/CdS NCs and discovered that at high pump fluences the carrier transport could reach a long distance of ∼2 µm within ∼30 ps after laser pulse excitation. This intriguing behavior is attributed to the metal-insulator transition and the associated bandlike transport, which are promoted by the enhanced electronic coupling among neighboring NCs with extended wave functions overlap of the excited-state charge carriers. Besides providing fundamental transport information in the regime of high laser pump fluences, the above findings shed light on the rational design of high-power light detecting schemes based on colloidal NCs.

Liraglutide Attenuates Aortic Valve Calcification in a High-Cholesterol-Diet-Induced Experimental Calcific Aortic Valve Disease Model in Apolipoprotein E-Deficient Mice.

BACKGROUND: Calcific aortic valve disease (CAVD) is a significant cause of morbidity and mortality among elderly people. However, no effective medications have been approved to slow or prevent the progression of CAVD. Here, we examined the effect of liraglutide on aortic valve stenosis. METHODS: Male Apoe-/- mice were fed with a high-cholesterol diet for 24 weeks to generate an experimental CAVD model and randomly assigned to a liraglutide treatment group or control group. Echocardiography and immunohistological analyses were performed to examine the aortic valve function and morphology, fibrosis, and calcium deposition. Plasma Glucagon-like peptide-1 (GLP-1) levels and inflammatory contents were measured via ELISA, FACS, and immunofluorescence. RNA sequencing (RNA-seq) was used to identify liraglutide-affected pathways and processes. RESULTS: Plasma GLP-1 levels were reduced in the CAVD model, and liraglutide treatment significantly improved aortic valve calcification and functions and attenuated inflammation. RNA-seq showed that liraglutide affects multiple myofibroblastic and osteogenic differentiations or inflammation-associated biological states or processes in the aortic valve. Those liraglutide-mediated beneficial effects were associated with increased GLP-1 receptor (GLP-1R) expression. CONCLUSIONS: Liraglutide blocks aortic valve calcification and may serve as a potential therapeutic drug for CAVD treatment.

Thiacalix[4]arene-protected alkynyl Agn (n = 9, 18) nanoclusters: syntheses, structural characterizations, photocurrent responses and fluorescence properties.

Two thiacalix[4]arene-protected silver(I) alkynyl nanoclusters, [Na2(H2O)2][Ag9(TC4A)(tBuCC)4(CH3OH)2(SbF6)0.5(OH)2.5]·3.5H2O·CH3OH (1, abbreviated as Ag9) and [Ag9(TC4A)(tBuCC)4(CF3COO)]2·4CH3OH (2, abbreviated as Ag18), were synthesized by the reaction of [tBuCCAg]n, p-tert-butylthiacalix[4]arene (H4TC4A), NaBH4, and AgSbF6 or CF3COOAg in the mixed solvent of methanol-trichloromethane-toluene under solvothermal conditions, respectively. Driven by SbF6- and CF3COO- with different coordination properties, the structural unit [Ag9(TC4A)(tBuCC)4]+ in both the compounds migrated in different modes, accompanied by distinct Ag⋯Ag distances. Ag9 and Ag18 exhibit similar UV-Vis absorption and diffuse reflection spectra along with contrary tendency between photocurrent responses and solid-state fluorescence. The solution stability of Ag9 and Ag18 was demonstrated by 1H NMR and MALDI-TOF mass spectrometry. The fluorescence responses of Ag9 and Ag18 towards different organic molecules were also investigated, which indicated that the polarity of solvent has a certain effect on the emission intensities of Ag9 and Ag18. This study provides a positive guide for the controlled synthesis and further study of the structure-activity relationship of thiacalix[4]arene-protected silver alkynyl nanoclusters.

Post-synthetic atomically precise single-CuII sites in a thiacalix[4]arene-supported octahedral Na@Co24 cluster: the Cu-Co synergistic effect for selective photocatalytic conversion of CO2 to CO.

A thiacalix[4]arene-supported octahedral Na@Co24 cluster has been fabricated by the modular assembly of six Co4-(TC4A) polynuclear secondary building units (PSBUs) and eight 2,4,6-PTC linkers. The post-modification of Na@Co24 by ion exchange of Na+ with Cu2+ on the surface of the octahedron afforded a structurally well-defined Cu@Co24 cluster. The obtained Cu@Co24 cluster achieved improved visible-light absorption and selective photoreduction of CO2 to CO due to the Cu-Co synergistic effect.

Tyrosine-Conjugation Method for Evaluating BACE1 Activity Based on Silver Nanoparticles/Metal-Organic Framework Composites as Electrochemical Tags.

Beta-site secretase (BACE1) catalyzes the cleavage of amyloid precursor protein (APP), which process ultimately lead to plaque deposition in the brain of Alzheimer's disease (AD). Thus, accurate monitor of BACE1 activity is essential to screen inhibitors for AD treatment. This study develops a sensitive electrochemical assay for probing BACE1 activity based on silver nanoparticles (AgNPs) and tyrosine conjugation as tags and a marking method, respectively. An APP segment is firstly immobilized on aminated microplate reactor. Cytosine (C) rich sequence-templated AgNPs/Zr-based metal-organic framework (MOF) composite is modified by phenol groups, and then the prepared tag (ph-AgNPs@MOF) is captured in microplate surface by the conjugation reaction of phenolic groups between tyrosine and tag. After cleavage by BACE1, the solution containing ph-AgNPs@MOF tags is transferred to the screen-printed graphene electrode (SPGE) surface for voltammetric detection of AgNP signal. This sensitive detection for BACE1 provided an excellent linear relationship between 1 to 200 pM with a detection limit of 0.8 pM. Furthermore, this electrochemical assay is successfully applied for screening of BACE1 inhibitors. This strategy is also verified to be used for evaluation of BACE1 in serum samples.

Joint equalization of EEPN, RSOP, and CD with the sliding window assisted extended Kalman filter for a high baud rate Stokes vector direct detection system.

Equalization-enhanced phase noise (EEPN) has emerged as one of the major impairments that cannot be ignored for a high baud rate Stokes vector direct detection (SVDD) system. When EEPN interacts with the rotation of state-of-polarization (RSOP) and chromatic dispersion (CD), the joint impairment effects become even more complicated. To achieve the joint equalization of EEPN, RSOP, and CD impairments of a high baud rate SVDD system, this paper first derives a joint impairment model of these three kinds of impairments, and then proposes a joint equalization scheme of EEPN, RSOP, and CD with a sliding window assisted extended Kalman filter (SWA-EKF). The SWA-EKF scheme first tracks RSOP in the time domain, subsequently compensates CD in the frequency domain, and finally performs EEPN mitigation in the time domain again. The effectiveness of the proposed scheme has been verified by a 60 GBaud SVDD-16QAM simulation system. The results show that when these three impairments are jointly equalized, the SWA-EKF scheme can track RSOP as fast as 3 Mrad/s, cumulative dispersion up to 1600 ps/nm, and EEPN caused by laser linewidth up to 3 MHz. In addition, with an optical signal-to-noise ratio penalty of 0.3 dB, it could increase 35 G baud rate under 3 MHz laser linewidth for the SVDD system. More importantly, its total complexity can be reduced to an order of O(N log N).

Carboxylate Ligand-supported Agn (n=21 and 24) Alkynyl Clusters Induced by Single/Double Carbonate Ions.

Structural transformation is important for the study of silver cluster compounds, in which controlled synthesis of their shapes and sizes via anion template-driven is one key scientific question. In this work, the CO3 2- anion templates were captured by the [t BuC≡CAg]n system under the stimulation induced by carboxylate ligand CF3 COO- /PhCOO- , and two silver alkynyl clusters [(CO3 2- )@Ag21 (t BuC≡C)16 (CF3 COO)3 (H2 O)]⋅DMF⋅2CH2 Cl2 (1) and [(CO3 2- )2 @Ag24 (t BuC≡C)16 (PhCOO)4 ]⋅CH3 OH⋅4DMF (2) have been successfully isolated and charactered. With the increase of the number of CO3 2- templates from single to double, the outer silver atoms from twenty-one to twenty-four, accompanied by the growth of the cluster skeleton from 9.8 Š×6.9 Šof the (CO3 2- )@Ag21 unit to 10.5 Š×7.3 Šof the (CO3 2- )2 @Ag24 unit. In addition, the syntheses, structures, photocurrent responses, cyclic voltammetry characteristics, luminescence, and photodegradation of compounds 1 and 2 have been studied.

Thiacalix[4]arene-Sandwiched Sandglass-like Ln9 Clusters (Ln = Tb and Eu): Insights into the Selective Luminescence Quenching Properties by p-Nitrobenzene Derivatives.

Nonanuclear lanthanide clusters Ln9 (Ln = Tb and Eu) based on p-tert-butylthiacalix[4]arene (H4TC4A) have been synthesized by the solvothermal reaction and were structurally determined by single-crystal X-ray diffraction. The framework of Ln9 can be termed as a sandglass-like structure whose two Ln4-TC4A polynuclear secondary building units are bridged by one octa-coordinate {Ln(µ3-O)8} unit. Efficient TC4A-to-Ln energy transfer was observed for Tb9 but not for Eu9. The luminescence quantum yield (QY) of Tb9 in the solid state at room temperature was determined to be 17.6%, while its highest QY in a methanolic solution (2 × 10-5 mol/L) is 59.2% upon excitation at 318 nm. The luminescence of Tb9 was quenched selectively by derivatives of p-nitrobenzene, as demonstrated by the results of photoluminescence and UV-vis titration experiments and supported by density functional theory calculations. We believe that the interactions between the analyte molecules and the pocket of Tb9 are primarily responsible for the observed quenching. As such, this work represents one of the few examples of utilizing structurally interesting lanthanide cluster complexes as a sensory platform for the recognition of meaningful analytes and portends the further development of lanthanide-calixarene-complex-based functional materials.

Trapping a [W10 O32 ]6- Decatungstate Anion in an Ag44 Nanowheel.

Compound [Ag44 (W10 O32 )(St Bu)24 (CF3 COO)8 ](CF3 COO)6 ⋅ 6H2 O (1) was synthesized through a one-pot method. This is the first case of isolating a new silver thiolate cluster containing a [W10 O32 ]6- template which transforms from WO4 2- polyoxoanion through a self-assembly process. The anionic nature of the reduced [W10 O32 ]6- template and the effective silver-oxygen interaction contribute to the formation of the Ag44 nanowheel in 1. The luminescence, photocatalytic activity and electrochemistry properties of 1 were studied.

Blind modulation format identification based on improved PSO clustering in a 2D Stokes plane.

Blind modulation format identification (MFI) is indispensable for correct signal demodulation and optical performance monitoring in future elastic optical networks (EON). Existing MFI schemes based on a clustering algorithm in Stokes space have gained good performance, while only limited types of modulation formats could be correctly identified, and the complexities are relatively high. In this work, we have proposed an MFI scheme with a low computational complexity, which combines an improved particle swarm optimization (I-PSO) clustering algorithm with a 2D Stokes plane. The main idea of I-PSO is to add a new field of view on each particle and limit each particle to only communicate with its neighbor particles, so as to realize the correct judgment of the number of multiple clusters (local extrema) on the density images of the s2-s3 plane. The effectiveness has been verified by 28 GBaud polarization division multiplexing (PDM)-BPSK/PDM-QPSK/PDM-8QAM/PDM-16QAM/PDM-32QAM/PDM-64QAM simulation EON systems and 28 GBaud PDM-QPSK/PDM-8QAM/PDM-16QAM/PDM-32QAM proof-of-concept transmission experiments. The results show that, using this MFI scheme, the minimum optical signal-to-noise ratio (OSNR) values to achieve 100% MFI success rate are all equal to or lower than those of the corresponding 7% forward error correction (FEC) thresholds. At the same time, the MFI scheme also obtains good tolerance to residual chromatic dispersion and differential group delay. Besides that, the proposed scheme achieves 100% MFI success rate within a maximum launch power range of -2∼+6 dBm. More importantly, its computational complexity can be denoted as O(N).

Co9 S8 @CN Composites Obtained from Thiacalix[4]arene-Based Coordination Polymers for Supercapacitor Applications.

Metal sulfides have been recognized as promising electrodes for electrochemical energy storage owing to their remarkable electrochemical properties. Here, we demonstrate the preparation of Co9 S8 nanoparticles anchored on a carbon matrix (denoted as Co9 S8 -X@CN (X=1, 2)) from precursor sources, two 1D infinite coordination polymers 1 and 2. The two polymers were assembled by linking Co4 -TC4A secondary building blocks (SBUs) with ligands L1 and L2 , respectively (H4 TC4A=p-tert-butylthiacalix[4]arene, L1 =1,4-bis(2H-tetrazol-5-yl)benzene, L2 =1,3-bis(2H-tetrazol-5-yl)benzene). The composites obtained from 1D polymers showed different morphologies, that is, the Co9 S8 nanoparticles of Co9 S8 -1@CN are octahedral with a size of ca. 140 nm, while the lamellar Co9 S8 nanoparticles in Co9 S8 -2@CN possess different sizes (50-150 nm). The Co9 S8 -2@CN immobilized on nickel foam (Co9 S8 -2@CN/NF) show better supercapacitive performance than that of Co9 S8 -1@CN. Co9 S8 -2@CN showed exceptionally high activities, combining higher specific capacitances (445.2 F g-1 at 2 A g-1 and 393.9 F g-1 and 5 A g-1 ), rate capacity (94.5% retention at 2 A g-1 ), and long-term stability (79.2% retention at 5 A g-1 over 1000 cycles). The smaller size and larger BET surface area of Co9 S8 -2@CN nanoparticles can improve the electrical conductivity and provide facile pathways for charge transport, thus leading to conspicuous electrochemical performance of Co9 S8 -2@CN compared with its Co9 S8 -1@CN counterpart.

Thiacalix[4]arene-supported molecular clusters for catalytic applications.

Thiacalixarenes are intriguing ligands that have attracted sustained interest because of their changeable conformations and excellent coordination ability. Thiacalix[4]arene analogues, which can bind metal ions to form modular second building units, are capable of constructing molecular-based functional materials with defined structures and various applications via directional coordination assembly. Due to rich metal-sulfur bonds, thiacalix[4]arene-based molecular clusters also exhibit diverse properties compared to other clusters. In particular, the combination of thiacalixarenes with currently popular molecular architectures, such as high-nuclearity clusters and coordination cages, has shown special catalytic performances. In this perspective, the latest advances in catalytic applications of thiacalix[4]arene-based molecular clusters, including molecular clusters themselves as catalysts and coordination cages serving as reaction vessels encapsulating metal nano-components for catalysis, are highlighted.

Thiacalix[4]arene-Protected Titanium-Oxo Clusters: Influence of Ligand Conformation and Ti-S Coordination on the Visible-Light Photocatalytic Hydrogen Production.

p-tert-Butylthiacalix[4]arene (H4TC4A)-decorated tetranuclear (Ti4) and hexanuclear (Ti6) polyoxo-titanium clusters (PTCs) were synthesized in isopropyl alcohol by a low-temperature solvothermal method. The structures were determined by single-crystal X-ray diffraction, in which the ligands adopt 1,2-alternative and cone-shaped conformations, respectively. Both PTCs show UV-vis absorptions up to 600 nm with band gaps at 2.19 eV (Ti4) and 2.24 eV (Ti6), respectively. Visible-light photocatalytic H2 production for Ti4 was measured to be 73.56 µmol/(g h), which is almost 5 times of that of Ti6 (15.16 µmol/(g h)). Results of density functional theory (DFT) calculations suggested that the different Ti-S coordination modes originating from the conformational disparity of the ligands are primarily responsible for the observed different photocatalytic activities. Not only does this work provides a better understanding of the structure-property relationships in using titanium-oxo clusters for photocatalytic H2 production but it also offers a means of tuning the band gap of the catalysts by varying the conformations of the ligands.

A hierarchically assembled 88-nuclei silver-thiacalix[4]arene nanocluster.

Thiacalix[4]arenes as a family of promising ligands have been widely used to construct polynuclear metal clusters, but scarcely employed in silver nanoclusters. Herein, an anion-templated Ag88 nanocluster (SD/Ag88a) built from p-tert-butylthiacalix[4]arene (H4TC4A) is reported. Single-crystal X-ray diffraction reveals that C4-symmetric SD/Ag88a resembles a metal-organic super calix comprised of eight TC4A4- as walls and 88 silver atoms as base, which can be deconstructed to eight [CrO4@Ag11(TC4A)(EtS)4(OAc)] secondary building units arranged in an annulus encircling a CrO42- in the center. Local and global anion template effects from chromates are individually manifested in SD/Ag88a. The solution stability and hierarchical assembly mechanism of SD/Ag88a are studied by using electrospray mass spectrometry. The Ag88 nanocluster represents the highest nuclearity metal cluster capped by TC4A4-. This work not only exemplify the specific macrocyclic effects of TC4A4- in the construction of silver nanocluster but also realize the shape heredity of TC4A4- to overall silver super calix.

A one-dimensional infinite silver alkynyl assembly [Ag8(C[triple bond, length as m-dash]C t Bu)5(CF3COO)3(CH3CN)] n : synthesis, crystal structure and properties.

A high-yield silver alkynyl assembly [Ag8(C[triple bond, length as m-dash]C t Bu)5(CF3COO)3(CH3CN)] n (1) constructed from [AgC[triple bond, length as m-dash]C t Bu] n ligand, CF3COOAg and CH3CN auxiliary ligands with a one-dimensional infinite chain structure has been obtained in one pot. Compound 1 has been well-defined and characterized. The photocurrent properties and the temperature-sensitive luminescent properties of 1 have been investigated.

A Temperature-Sensitive Luminescent Ag42 Nanocluster Supported by TertButyl Thiol Ligands.

Compound [Ag42 S5 (StBu)25 (CF3 COO)4 (CO3 )](CO3 )0.5 ⋅CH2 Cl2 ⋅4CH3 OH⋅9DMF (1) has been obtained and well defined. It consists of a multi-shell structure involving two Ag centres, one Ag5 S5 pentagram, two Ag5 S5 pentagons and one Ag25 S15 shell. Compound 1 has been characterized by XPS, FT-IR, PXRD, TGA, NMR, MS, UV/Vis spectrum, TEM and cyclic voltammetry. Temperature-sensitive luminescent property of 1 has also been investigated.

Thiacalixarene-Supported Irregular Co26 and Ni28 High-Nuclearity Clusters with Pyridyl-Diphosphonates: Strategies to Create Active Metal Sites and Fabricate Multicomponent Materials.

Two new irregularity high-nuclearity clusters [Co26(TC4A)6(HL)4Cl4(HCOO)4(CH3O)2(OH)2(DMF)10(H2O)5] (+ solvent) (Co26) and [Ni28(TC4A)6(HL)6(PO4)2(µ3-O)2Cl2(CH3OH)14(H2O)2(DMF)8][(CH3NH2CH3)4] (+ solvent) (Ni28) have been solvothermally synthesized by p- tert-butylthiacalix[4]arene (H4TC4A), transition metals (CoCl2·6H2O/NiCl2·6H2O), and 1-hydroxy-2-(3-pyridinyl)ethylidene-1,1-diphosphonic acid (H5L). The clusters were structurally characterized by single crystal X-ray diffraction, PXRD, TGA, and FT-IR spectrum and Raman spectrum. Co26 features a rodlike Co26 core constructed by six Co4-TC4A secondary building units (SBUs) and four HL4- with two extra cobalt ions. Ni28 cluster represents a flowerlike Ni28 core built from six Ni4-TC4A SBUs, six HL4-, and four additional nickel ions. The multidentate risedronic acid displaying various new coordination mode bonds with SBUs to assemble two nanoclusters that enable high density possible coordinatively unsaturated metal sites (PCUMSs). Co26 and Ni28 clusters can be directly dispersed on carbon paper (CP) and showed extraordinary oxygen evolution reaction (OER) activity due to the larger exposed liable coordination active metal sites. The thermodecomposition of both nanoclusters at different temperatures afforded serial multicomponent complexes.

High proton conductivity behavior in a 2D metal sulfite constructed from a histidine ligand.

In the presence of the amino acid histidine, an inorganic-organic hybrid metal sulfite, Zn2(SO3)2(C6N3O2H9)2·H2O (1), has been prepared under hydrothermal conditions. Single-crystal X-ray diffraction analysis reveals that 1 shows a 2D layer framework built up from a classical second building unit (S4R), and bridged histidine molecule. Notably, it is the first report of a metal sulfite in the presence of an amino acid molecule. A 1D H-bonding array can be constructed by the H-bonding interaction between histidine molecules and sulfite groups. Moreover, a new function of metal sulfite for proton conduction was investigated by alternating-current impedance analysis. The results demonstrate that compound 1 shows a high proton conductivity of approximately 10-3 S cm-1 at 348 K and 98% relative humidity.