Parallel edge extraction operators on chip speed up photonic convolutional neural networks.

We experimentally establish a 3 × 3 cross-shaped micro-ring resonator (MRR) array-based photonic multiplexing architecture relying on silicon photonics to achieve parallel edge extraction operations in images for photonic convolution neural networks. The main mathematical operations involved are convolution. Precisely, a faster convolutional calculation speed of up to four times is achieved by extracting four feature maps simultaneously with the same photonic hardware's structure and power consumption, where a maximum computility of 0.742 TOPS at an energy cost of 48.6 mW and a convolution accuracy of 95.1% is achieved in an MRR array chip. In particular, our experimental results reveal that this system using parallel edge extraction operators instead of universal operators can improve the imaging recognition accuracy for CIFAR-10 dataset by 6.2% within the same computing time, reaching a maximum of 78.7%. This work presents high scalability and efficiency of parallel edge extraction chips, furnishing a novel, to the best of our knowledge, approach to boost photonic computing speed.

On-chip silicon photonic micro-ring processor lights up optical image encryption.

Optical image encryption has long been an important concept in the fields of photonic network processing and communication. Here, we propose a convolution-like operation-based optical image encryption algorithm exploiting a silicon photonic multiplexing architecture to achieve content security. Particularly, the encryption process is completed in a 3 × 3 cross-shaped photonic micro-ring resonator (MRR) array on chip. For the first time, to the best of our knowledge, this algorithm encodes information in an integrated intensity modulation, effectively reducing the encoding difficulty. Moreover, the high reliability and scalability of optical encryption are ensured using both linear and nonlinear operations on photonic chips according to characteristics of MRRs. As the encryption and decryption experiments show, the image restoration accuracy of our optical encryption algorithm exceeds 99% under real system noise at the pixel level, indicating its noise-robust property. Meanwhile, the peak signal-to-noise ratios of the restored and encrypted images are >60 and <15 dB, respectively, revealing both the high accuracy of the restored image and the small correlation between the encrypted and original images. This work adds to the rapidly expanding field of optical image encryption on photonic chips.

In Vitro and In Vivo Antitumor Assay of Mitochondrially Targeted Fluorescent Half-Sandwich Iridium(III) Pyridine Complexes.

Half-sandwich iridium(III) complexes show potential value in the anticancer field. However, complexes with favorable luminescence performance are rare, which limits further investigation of the anticancer mechanism. In this paper, 10 triphenylamine-modified fluorescent half-sandwich iridium(III) pyridine complexes {[(η5-Cpx)Ir(L)Cl2]} (Ir1-Ir10) were prepared and showed potential antiproliferative activity, effectively inhibiting the migration of A549 cells. Ir6, showing the best activity among these complexes, exhibited excellent fluorescence performance (absolute fluorescence quantum yield of 15.17%) in solution. Laser confocal detection showed that Ir6 followed an energy-dependent cellular uptake mechanism, specifically accumulating in mitochondria (Pearson co-localization coefficient of 0.95). A Western blot assay further confirmed the existence of a mitochondrial apoptotic channel. Additionally, Ir6 could arrest the cell cycle at the G2/M phase, catalyze NADH oxidation, reduce the mitochondrial membrane potential, induce an increase in the level of intracellular reactive oxygen species, and exhibit a mechanism of oxidation. An in vivo antitumor assay confirmed that Ir6 can effectively inhibit tumor growth and is safer than cisplatin.

Carbon deficit checks in high resolution and compensation under regional inequity.

Carbon compensation is an effective way of reducing carbon emissions. However, previous studies in this field have been limited and have not examined high-precision scientific carbon compensation under regional inequity. The present study examined initial carbon compensation in the grid and developed a new equitable carbon compensation model. Additionally, it modified the carbon compensation value for each province and analysed how land-use change affected carbon compensation. The results show that, after the modification, the entire carbon deficit reached 17.34 × 108 t C in 2015, representing a decrease of 14% compared with the initial carbon deficit. The area with negative carbon deficit values accounted for 36% of the whole area, concentrated mainly in the south, southwest and northwest. Without modification, the initial carbon compensation reached 537 × 108 USD, and only Yunnan, Sichuan and Hainan provinces being eligible to receive compensation. The final modified carbon compensation was approximately 20% of the initial values, and 11 provinces were eligible to obtain compensation. The other provinces responsible for paying the carbon compensation costs were typically concentrated in Central and Eastern China. Land-use changes in 2015 led to increases in the initial carbon compensation and modified carbon compensation of 3.74 × 108 and 0.13 × 108 USD, respectively. The per-unit land-use change caused greater increases in carbon emissions in China's big cities and the provinces in Central and East China. Some policies, such as macro-control by the central government, diversified forms and patterns of compensation, and auxiliary measures should be formulated/proposed.

Photoexcited Chiral Copper Complex-Mediated Alkene E → Z Isomerization Enables Kinetic Resolution.

While asymmetric synthesis has been established as a powerful synthetic tool for the construction of versatile enantioenriched molecules in the most efficient and practical manner, the resolution of racemates is still the most universal industrial approach to the synthesis of chiral compounds. However, the direct formation of enantiopure Z-isomers through the catalytic nonenzymatic kinetic resolution of racemic E-alkenes remains challenging. Herein, we disclose an unprecedented enantioselective E → Z isomerization mediated by a photoexcited chiral copper complex. This catalytic system enables kinetic resolution of 2-styrylpyrrolidines. This process is difficult to realize under thermal conditions. Mechanistic experiments and density functional theory (DFT) calculations revealed that different overall sensitization rates of the substrate-catalyst complex of the two enantiomers led to the observed excellent kinetic resolution efficiency. This photochemical transformation expands the potential of kinetic resolution beyond their established ground-state reactivity, furnishing a novel reaction mode for enantioselective catalysis at its excited state.

Ultrafast resonant exciton-plasmon coupling for enhanced emission in lead halide perovskite with metallic Ag nanostructures.

Integrating metal halide perovskites onto plasmonic nanostructures has recently become a trending method of enabling superior emissive performance of perovskite nanophotonic devices. In this work, we present an in-depth study on the spontaneous emission properties of hybrid systems comprising CsPbBr3 nanocrystals and silver nanostructures. Specifically, a 5.7-fold increment of the photoluminescence (PL) intensity and a 1.65-fold enhancement of the PL relaxation rate is attained when the transition energy of CsPbBr3 is spectrally resonant with the oscillational frequency of Ag nanodisks (NDs), which is attributed to the intense exciton-plasmon coupling-induced Purcell effect. Furthermore, a 540-fs ultrafast energy transfer from the CsPbBr3 excitons to Ag plasmons is revealed by femtosecond pump-probe experiments, suggesting the key mechanism responsible for the Purcell-enhanced radiative emission. Our finding offers a unique understanding of the enhanced emissive behavior in the plasmon-coupled perovskite system and paves the way for further applications.

Distinctive Mechanistic Scenarios and Substituent Effects of Gold(I) versus Copper(I) Catalysis for Hydroacylation of Terminal Alkynes with Glyoxal Derivatives.

Density functional theory (DFT) calculations have been conducted to study the mechanisms, substituent effects, and the role of bases in Au- and Cu-catalyzed hydroacylation of terminal alkyne with glyoxal derivatives. The two reactions, despite being catalyzed by the same group of transition metals, follow distinctive reaction mechanisms. Through the detailed DFT calculations, insights into the mechanisms are obtained, and the substituent effects and the role of the bases are understood.

Insights into α-Alkynylation and α-Allenylation of Aldehydes under the Synergisitic Catalysis of Gold/Amine: A DFT Study.

A mechanistic investigation of α-alkynylation and α-allenylation of aldehydes under the synergistic catalysis of AuCl/amine was performed using density functional theory (DFT) calculations. For such a reaction that delivers two products, this study reveals that the reaction undergoes such a mechanistic mode: reactants → alkynyl product → allenyl product, implying that the allenyl product cannot be obtained directly from reactants. The product ratio obtained experimentally was rationalized based on the computed results that both products can reversibly interconvert with AuCl as the catalyst and with N-containing Lewis bases as additives such as 4,5-diazafluorenone. For the relative stability of alkynyl versus allenyl compounds, unsaturated substituents are found to favor the allenyl compounds.

Noncovalent Interaction- and Steric Effect-Controlled Regiodivergent Selectivity in Dimeric Manganese-Catalyzed Hydroarylation of Internal Alkynes: A Computational Study.

Selective hydroarylation of internal alkynes catalyzed by a dimeric manganese complex provides a powerful strategy for the construction of multisubstituted alkenes. In this work, density functional theory (DFT) calculations and experimental studies were carried out to explore the mechanism and origin of regiodivergent hydroarylation of internal alkynes reported by our group. The results demonstrate that this reaction first proceeds via a bimetallic mechanism to generate the active catalyst that subsequently undergoes a monometallic mechanism to run the three-stage catalytic cycle: alkyne migratory insertion, protonation, and active catalyst regeneration. Alkyne migratory insertion is considered as the regioselectivity-determining step. Energy decomposition analyses on insertion transition states suggest that the interaction between the substrate and catalyst is mainly responsible for the observed exclusive γ-selectivity of 1a, while the deformation of these two sections induced by the sterically hindered phenyl group and aryl group accounts for the complete ß-position arylation of 1e. The decrease of γ-selectivity with the regulation of a tertiary alcohol motif in 1a originates from the reduced noncovalent interaction. The computational results provide important insights into the origin of regiodivergent selectivities and useful information for further designing and adjusting the strategy in Mn-catalyzed alkyne hydroarylation.

Enhanced Terahertz Radiation by Efficient Spin-to-Charge Conversion in Rashba-Mediated Dirac Surface States.

The enhancement of terahertz (THz) radiation is of extreme significance for the realization of the THz probe and imaging. However, present THz technologies are far from being enough to realize high-performance and room-temperature THz sources. Fortunately, topological insulators (TIs), with spin-momentum-locked Dirac surface states, are expected to exhibit a high terahertz emission efficiency. In this work, the novel concept of a Rashba-state-enhanced spintronic THz emitter is demonstrated on the basis of ferromagnet/heavy metal/topological insulator (FM/HM/TI) heterostructure. We find that the THz emission intensity changes as a function of HM interlayer thickness, and a 1.98 times higher intensity compared to that of FM/TI can be achieved when a meticulously designed thickness of the HM layer is inserted. The improvement of terahertz radiation is ascribed to the additive effect of Rashba splitting and topological surface states at the HM/TI interface. These results offer new possibilities for realizing spintronic THz emitters in TI-based magnetic heterostructures.

Preparation and Bioactivity of Iridium(III) Phenanthroline Complexes with Halide Ions and Pyridine Leaving Groups.

A series of half-sandwich structural iridium(III) phenanthroline (Phen) complexes with halide ions (Cl- , Br- , I- ) and pyridine leaving groups ([(η5 -CpX )Ir(Phen)Z](PF6 )n , Cpx : electron-rich cyclopentadienyl group, Z: leaving group) have been prepared. Target complexes, especially the Cpxbiph (biphenyl-substituted cyclopentadienyl)-based one, showed favourable anticancer activity against human lung cancer (A549) cells; the best one (Ir8) was almost five times that of cisplatin under the same conditions. Compared with complexes involving halide ion leaving groups, the pyridine-based one did not display hydrolysis but effectively caused lysosomal damage, leading to accumulation in the cytosol, inducing an increase in the level of intracellular reactive oxygen species and apoptosis; this indicated an anticancer mechanism of oxidation. Additionally, these complexes could bind to serum albumin through a static quenching mechanism. The data highlight the potential value of half-sandwich iridium(III) phenanthroline complexes as anticancer drugs.

Diastereoselective and Stereodivergent Synthesis of 2-Cinnamylpyrrolines Enabled by Photoredox-Catalyzed Iminoalkenylation of Alkenes.

A photoredox-catalyzed iminoalkenylation of γ-alkenyl O-acyl oximes has been developed. Readily available alkenylboronic acids serve as alkenylation reagents, leading to densely functionalized pyrrolines. Both (E)- and (Z)-cinnamylpyrrolines are accessible depending on the reaction solvent. In dichloromethane, (E)-cinnamylpyrrolines are produced through a photoredox-mediated single-electron-transfer process. In tetrahydrofuran, (Z)-cinnamylpyrrolines are generated by photocatalytic contra-thermodynamic E-to-Z isomerization of (E)-cinnamylpyrrolines though an energy-transfer pathway. Two stereocenters are established with complete diastereoselectivity and only one diastereomer is isolated.

Dimeric Manganese-Catalyzed Hydroarylation and Hydroalkenylation of Unsaturated Amides.

An unprecedented Mn(I)-catalyzed selective hydroarylation and hydroalkenylation of unsaturated amides with commercially available organic boronic acids is reported. Alkenyl boronic acids have been successfully employed for the first time in Mn(I)-catalyzed carbon-carbon bond formation. A wide array of ß-alkenylated amide products can be obtained in moderate to good yields, which offers practical access to five- and six-membered lactams. This protocol has predictable regio- and chemoselectivity, excellent functional group compatibility and ease of operation in air, representing a significant step-forward towards manganese-catalyzed C-C coupling.

A Highly Efficient Dimeric Manganese-Catalyzed Selective Hydroarylation of Internal Alkynes.

We have developed a general and site-predictable manganese-catalyzed hydroarylation of internal alkynes in the presence of water, under an air atmosphere without the involvement of ligand. The unique catalytic feature of this reaction is highlighted by comparison with other widely used transition metal catalysts including palladium, rhodium, nickel, or copper. The simple operation, high efficiency and excellent functional group compatibility make this protocol practical for more than 90 structurally diverse internal alkynes, overcoming the influence of both electronic and steric effect of alkynes. Its exclusive regio- and chemoselectivity originates from the unique reactivity of the manganese-based catalyst towards an inherent double controlled strategy of sterically hindered propargyl alcohols without the installing of external directing groups. Its synthetic robustness and practicality have been illustrated by the concise synthesis of bervastatin, a hypolipidemic drug, and late-stage modification of complex alkynes with precise regioselectivity.

New Organometallic Tetraphenylethylene⋠Iridium(III) Complexes with Antineoplastic Activity.

Iridium(III) complexes have attracted more and more attention in the past few years because of their potential antineoplastic activity. In this study, four IrIII complexes of the types [(η5 -Cpx )Ir(N^N)Cl]PF6 (complexes 1 and 2) and [Ir(Phpy)2 (N^N)]PF6 (complexes 3 and 4) have been synthesized and characterized. They exhibit potential antineoplastic activity towards A549 cells, especially in the case of complex 1 [IC50 =(3.56±0.5) µm], which was nearly six times as effective as cisplatin [(21.31±1.7) µm]. Additionally, these complexes show some selectivity towards cancer cells over normal cells. They could be transported by serum albumin (binding constants were changed from 0.37×105 to 81.71×105 m-1 ). IrIII complexes 1 and 2 could catalyze the transformation of nicotinamide adenine dinucleotide reduced form (NADH) into NAD+ (turnover numbers 43.2, 11.9] and induce the accumulation of reactive oxygen species, thus confirming their antineoplastic mechanism of oxidation, whereas the cyclometalated complexes 3 and 4 were able to target the lysosome [Pearson co-localization coefficient (PCC)=0.73], cause lysosomal damage, and induce apoptosis. Understanding the mechanism of action would help further structure-activity optimization on these IrIII complexes as emerging cancer therapeutics.

Ultrafast nonlinear absorption enhancement of monolayer MoS2 with plasmonic Au nanoantennas.

In this work, we experimentally study the nonlinear absorption enhancement of saturable absorption and two-photon absorption on a hybrid structure comprising a monolayer MoS2 and Au nanoantennas via femtosecond I-scan measurement. Specifically, a 13-fold increment in the linear absorption coefficient is attained at 1.85 eV, along with an 8-fold enhancement of the two-photon absorption coefficient at 1.65 eV, which is attributed to exciton-plasmon coupling resonance and plasmonic hot electron transfer. The exciton-plasmon coupling effect is characterized by stable photoluminescence experiments. Furthermore, the exciton recombination time is extracted from the pump-probe measurement, whose value in the hybrid structure is shortened from 18.5 ps (pure MoS2) to 1.84 ps. Our findings facilitate a new perspective to modulate the nonlinear optical response and to promote the performance of nonlinear photonic devices.

Deoxygenative Arylation of Carboxylic Acids by Aryl Migration.

An unprecedented deoxygenative arylation of aromatic carboxylic acids has been achieved, allowing the construction of an enhanced library of unsymmetrical diaryl ketones. The synergistic photoredox catalysis and phosphoranyl radical chemistry allows for precise cleavage of a stronger C-O bond and formation of a weaker C-C bond by 1,5-aryl migration under mild reaction conditions. This new protocol is independent of substrate redox-potential, electronic, and substituent effects. It affords a general and promising access to 60 examples of synthetically versatile o-amino and o-hydroxy diaryl ketones under redox-neutral conditions. Furthermore, it also brings one concise route to the total synthesis of quinolone alkaloid, (±)-yaequinolone A2, and a viridicatin derivative in satisfying yields.

Ferrocene-Appended Iridium(III) Complexes: Configuration Regulation, Anticancer Application, and Mechanism Research.

A series of ferrocene-appended half-sandwiched iridium(III) phenylpyridine complexes have been designed and synthesized. These complexes show better anticancer activity than cisplatin widely used in clinic under the same conditions. Meanwhile, complexes could effectively inhibit cell migration and colony formation. Complexes could interact with protein and transport through serum protein, effectively catalyzing the oxidation of nicotinamide-adenine dinucleotid and inducing the accumulation of reactive oxygen species (ROS, 1O2), which confirmed the anticancer mechanism of oxidation. Furthermore, laser scanning confocal detection indicates that these complexes can enter cells followed by a non-energy-dependent cellular uptake mechanism, effectively accumulating in the lysosome (Pearson's colocalization coefficient: ∼0.90), leading to lysosome damage, and reducing the mitochondrial membrane potential (MMP). Taken together, ferrocene-appended iridium(III) complexes possess the prospect of becoming a new multifunctional therapeutic platform, including lysosome-targeted imaging and anticancer drugs.

Ultrafast exciton transfer in perovskite CsPbBr3 quantum dots and topological insulator Bi2Se3 film heterostructure.

Recently, topological insulator based heterostructures (HSs) have attracted tremendous research interest, due to their efficient carrier transfer features at the heterointerface induced by metallic surface states. Here, a novel HS comprising 0D perovskite CsPbBr3 quantum dots (QDs) and 2D material topological insulator Bi2Se3 film is proposed and experimentally investigated. Specifically, steady state and time-resolved photoluminescence (PL) measurements are employed, from which a significant quenching behaviour is observed in the HS, with an average quenching factor of 93.2 ± 0.8%. Additionally, time-resolved PL spectroscopy affirms that the carrier transfer efficiency can be up to 92.6 ± 0.2%. Furthermore, the dynamics of carrier transfer within the 0D-2D HS are characterized by utilizing femtosecond broadband transient absorption (TA) spectroscopy, revealing an ultrafast exciton transfer from photoexcited CsPbBr3 QDs to the Bi2Se3 film with a time-scale around 1.1 ± 0.2 ps. An alternative important finding is that the band renormalization is exhibited in CsPbBr3 QDs of the HS, with the dominant factor being the Coulomb screening effect. This work is expected to provide some fundamental understanding of the ultrafast and efficient carrier transfer mechanism underneath HSs based on topological insulators.

Deoxygenative Deuteration of Carboxylic Acids with D2 O.

We report a general, practical, and scalable means of preparing deuterated aldehydes from aromatic and aliphatic carboxylic acids with D2 O as an inexpensive deuterium source. The use of Ph3 P as an O-atom transfer reagent can facilitate the deoxygenation of aromatic acids, while Ph2 POEt is a better O-atom transfer reagent for aliphatic acids. The highly precise deoxygenation of complex carboxylic acids makes this protocol promising for late-stage deoxygenative deuteration of natural product derivatives and pharmaceutical compounds.