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Recently, chiral hybrid organic-inorganic perovskites (HOIPs) are drawing wide attention due to their intrinsic noncentrosymmetric structures which result in fascinating properties such as ferroelectronics and second-order nonlinear optics (NLO). However, previous research mainly focused on chiral lead-based halide perovskites ignoring that the toxic Pb element is harmful to humans and the environment. Herein, we successfully synthesized block-like (

(R-/S-Br-MBA)3MnBr5 shows reversible conversion of CPL emission in wavelength and direction during heating and cooling.

Achieving large luminescence dissymmetry factors (glum) is challenging in the research field of circularly polarized luminescence (CPL). While various approaches have been developed to construct organic systems with CPL activity, there is still a lack of effective methods for fabricating CPL active inorganic materials. Herein, we propose an approach for endowing upconversion nanoparticles (UCNPs) and perovskite nanocrystal (PKNC) hybrid nanomaterials with upconverted circularly polarized luminescence (UC-CPL) activity. Chiral cesium lead bromides (CsPbBr3) PKNCs were synthesized by a chiral-ligand-assistant method. Meanwhile, UCNP could be embedded into the chiral PKNC, enabling a photon upconvesion feature to the PKNC. The embedded UCNPs in PKNCs were confirmed by electron tomography. Consequently, various CPL activities, including prompt CPL, UC-CPL, and energy transfer enhanced circularly polarized luminescence (ET-CPL), were realized. The chiral perovskite nanocrystals could reabsorb the chiral energy generated from UCNPs, showing energy transfer enhanced CPL activity with four times magnification of the circular polarization. These findings provide a meaningful strategy for designing chiral photon upconversion inorganic nanomaterials with highly efficient UC-CPL activity.

2,3,5-Trimethylbenzoquinone (TMBQ)is a kind of crucial intermediate in the synthesis of Vitamin E, whose demand is increasing rapidly. The traditional synthesis method of TMBQ needs H2O2 or pure O2 as the oxidant, which is expensive and needs much attention in the production, transportation and storage process. In order to overcome the issues, the green oxidant, air, has been developed in this work to prepare TMBQ for the first time. TMBQ was synthesized from 2,3,6-trimethylphenol (TMP) with the oxidant of air in the solvent of isoamylol catalyzed by composite catalyst of inorganic salts at one atmosphere pressure. The critical reaction parameters, including the ingredient of composite catalyst, reaction time, reaction temperature, stirring speed and the addition of ionic liquids were investigated in order to achieve the optimal reaction condition. TMBQ was obtained with the conversion of 100% and selectivity of 96.7% at 90 °C for 7–8 h at one atmosphere pressure, over the composite catalyst, the aqueous solution of CuCl2, FeCl3 and MgCl2, with the help of ion liquid, 1-sulfobutyl-3-methylimidazole hydrochloride ([Bmim]Cl). Moreover, the catalyst could be recycled more than four times. Air is very cheap, abundant, eco-friendly and safe in production, transportation and storage process. The synthesis of TMBQ from TMP with air as oxidant at one atmosphere pressure has obvious advantages, which will bring new inspiration for the industrial production of TMBQ.

Single-shot ultrafast multi-frame imaging technology plays a crucial role in the observation of laser-induced plasma. However, there are many challenges in the application of laser processing, such as technology fusion and imaging stability. To provide a stable and reliable observation method, we propose an ultrafast single-shot multi-frame imaging technology based on wavelength polarization multiplexing. Through the frequency doubling and birefringence effects of the BBO and the quartz crystal, the 800 nm femtosecond laser pulse was frequency doubled to 400 nm, and a sequence of probe sub-pulses with dual-wavelength and different polarization was generated. The coaxial propagation and framing imaging of multi-frequency pulses provided stable imaging quality and clarity, as well as high temporal/spatial resolution (200 fs and 228 lp/mm). In the experiments involving femtosecond laser-induced plasma propagation, the probe sub-pulses measured their time intervals by capturing the same results. Specifically, the measured time intervals were 200 fs between the same color pulses and 1 ps between the adjacent different. Finally, based on the obtained system time resolution, we observed and revealed the evolution mechanism of femtosecond laser-induced air plasma filaments, the multifilament propagation of femtosecond laser in fused silica, and the influence mechanism of air ionization on laser-induced shock waves.

Novel flower-like Bi5O7I/Bi4Ti3O12 (BOI/BTO) photocatalysts were successfully designed and fabricated by an in situ growth method. The BOI and BTO in BOI/BTO composites have abundant interface contact and constructed a Z-scheme heterojunction structure. Therefore, these composites exhibited excellent performance for the selective oxidation of benzylic alcohols under visible light. It was attributed to the stronger absorption capacity of visible light and the high separation efficiency of photogenerated carriers via the Z-scheme transfer mechanism; especially, the sample BOI/BTO-1.5 achieved 92.4% selectivity for the oxidation of 4-methylbenzyl alcohol (4-MBA) to 4-methyl-benzaldehyde (4-MBAD) in the presence of H2O2, which also exhibited good stability, reusability and substrate adaptability. As evidenced by the activity experiments, trapping experiments and ESR analysis, the ˙O2− radicals and HOO˙ radicals were supposed to be the main active species directly involved in the photocatalytic oxidation process. Based on the optical and electrical analysis, a Z-scheme transfer facilitated mechanism of photocatalytic selective oxidation of benzylic alcohols was speculated.

The chirality of inorganic semiconductor nanocrystals (NCs) was demonstrated to be sensitive to the particle structures and chiral molecules capped on the NC surfaces. In this work, we found the native achiral ligands used for the synthesis of NCs could also influence their circular dichroism (CD) response. With different native ‘growth’ ligands but similar semiconductor cores, the CD spectra of NCs exhibited mirror images by using the same enantiopure cysteine (Cys) ligands, indicating the inversion of NC chirality. In addition, distinct anisotropic dissymmetry factors (g-factor) were observed. With appropriate native ligands, we prepared chiral cysteine stabilized spherical CdSe NCs (quantum dots, QDs) with the highest g-factor ever reported.

Three-dimensional (3D) nanomaterials have been intensively investigated because of their unique properties and wide range of potential applications; however, the ligand-induced chirality in 3D semiconductor nanocrystals has been scarcely studied. In this paper, we report the synthesis of hydrophobic 3D CdSe nanotetrapods (Tps) with a high degree of uniformity in their morphology by using the hot-injection method. The core and arms of Tps are distinct in their crystal structure, thus creating an intracrystal heterojunction. The size of Tps, primarily the length of four arms, is controlled by changing the amount of didecyldimethylammonium bromide and reaction time. Next, enantiopure cysteine ligands were introduced to replace the hydrophobic native stabilizers to prepare chiral l- and d-cysteine-capped CdSe Tps. Importantly, the circular dichroism (CD) line shapes of l/d-cysteine-capped CdSe Tps are assigned to the different excitonic transitions of the core and arms, respectively. In addition, the observed CD activities are found to be sensitive to the size of the CdSe Tps, where the anisotropic g factors have increased and reached the maximum value at a moderate aspect ratio (AR) and a further increase of the AR leads to a decrease of the g factor. Because of charge transfer between the core and arms, we propose a plausible mechanism potentially responsible for the induced CD line shapes in terms of the excitonic states of Tps with two different crystal structures. We believe that chiral 3D nanomaterials with anisotropic morphologies could offer new opportunities for relevant applications.

Stretchable conductors are important ingredients in the new emerging wearable systems. Here, intrinsically stretchable con­ductors (ISCs) based on carbon nanomaterials with a good balance of proper...

Synthesis of model compound of [FeFe]-hydrogenase active site is a promising and effective method to produce hydrogen. [μ-(SCH(CH2CH3)CH2S)–Fe2(CO)5]2-(κ1-DPPE) (compound 1) and [μ-(SCH(CH2CH3)CH2S)] Fe2(CO)5 (κ1-DPPM) (compound 2) were designed and synthesized. Compared 1 and 2 via IR, X-ray single crystal diffraction and CV, it was found that even through 1 and 2 shared similar electronic environment as well as crystal structure features, 1 with two symmetric [2Fe–2S] subsites had distinct reduction peaks and also showed higher electrocatalytic proton reduction efficiency in the presence of equivalent amount of HOAc, which indicated two symmetric [2Fe–2S] subsites played different roles in the process of proton reduction. Furthermore, -(κ1-DPPE)-[2Fe–2S] moiety with variable valence state in 1 can mimic the [4Fe–4S] cluster and serve as an electron shuttle.

BACKGROUND: Dihydroxybenzene (DHB) which is an important raw material and intermediate of the organic chemical industry can be prepared by hydroxylation of phenol, so it promotes the study of highly selective catalyst for hydroxylation of phenol. RESULTS: Two novel PNP ((Ph₂P)₂NPh) ligand‐substituted di‐iron complexes were synthesized under controllable reaction conditions via carbon monoxide (CO)/ligand substitution of the parent complex (μ‐budt)Fe₂(CO)₆ [budt = SCH(CH₃)CH₂CH₂)S]. The substituted complexes 1 and 2 were fully characterized by solution infrared spectroscopy, nuclear magnetoresonance spectroscopy, single crystal X‐ray diffraction, cyclic voltammetry and density functional theory calculations. Due to its favorable redox properties, Complex 1 was adopted first as an efficient catalyst for the hydroxylation of phenol to DHB (dihydroxybenzene) with hydrogen peroxide (H₂O₂) as oxidant and H₂O as solvent. Under the optimum reaction conditions, the conversion of phenol achieved 42.0%, the selectivity of DHB was ≤88.6% and the catechol:hydroquinone ratio (mol mol⁻¹) was 2.2. Furthermore, only trace amounts of benzoquinone, as a deeply oxidized product, was detected (yield c. 0.1%). CONCLUSION: Complex 1 could be a new type of catalyst for the hydroxylation of phenol to hydroquinone owing to the mild reaction conditions and excellent catalytic performance. In addition, a possible catalytic reaction mechanism was related to the special structure of Complex 1 which features an internal base of amine in PNP ligand.

Copper sulfide (Cu2−xS) is a kind of cation deficient transition metal sulfide, which has attracted great interest due to its unique properties that arise from degenerate vacancy-doping, particularly its tunable localized surface plasmon resonance (LSPR) properties. In this work, a range of vacancy-doped Cu2−xS nanocrystals (NCs) (Cu1.2S, Cu1.4S, Cu1.75S, and Cu1.94S NCs) with a size of around 10 nm was prepared with tunable LSPR through a hot injection method. The doping level was manipulated effectively by varying the injection volume of sulfur powder–oleic acid (S–OA) to finely tune the LSPR wavelength. Cu2−xS NCs with four different doping levels were investigated as photocatalysts for degradation of dyes. The Cu1.94S NCs with the highest LSPR energy exhibited the best photocatalytic activity due to the highest free carrier density, presumably influenced by Cu vacancies and the volume of the S–OA solution. Theoretical calculations of the free carrier density of Cu2−xS NCs are consistent with the order of the photocatalytic activity. The results demonstrate that the correlation of the photocatalytic activity with the corresponding concentration of free holes and the LSPR wavelength is of interest, which will provide inspiration for the design of non-noble metal catalysts by regulating the free hole concentration in degenerate p-doped Cu2−xS caused by cation vacancies.

In this study, a biomimetic method assisted by bacitracin was applied to prepare spherical BiVO4 nanoparticles. The obtained BiVO4 nanoparticles were extensively characterized by XRD, SEM, TEM, BET, XPS, TGA, FTIR, UV-vis, PL, EIS and photocurrent density tests. The results indicated that bacitracin played a vital role in the induction and assembly of spherical BiVO4 nanoparticles. At the proper calcination temperature, C doping was achieved in the process of calcining biological templates. Moreover, the spherical BiVO4 nanoparticles were investigated as photocatalysts for the degradation of tetracycline hydrochloride (TH) under visible light. The spherical BiVO4 nanoparticles prepared with the present biological template by calcination at 300 °C exhibited the most excellent photocatalytic performance, and 98% TH could be degraded within 60 min under visible light. Compared with other samples, the T-300 sample has a larger exposed reaction surface, narrower band gap and more suitable C content, which all lead to improvement in the photocatalytic activity.

The femtosecond laser ablation of metals is a complex and violent nonequilibrium process, and numerous studies have sought to reveal the evolution of a single physical phenomenon, such as laser-induced periodic surface micro-nanostructures or plasma eruptions. By considering the multiphysics scenarios of energy and heat transfer, structural mechanics, hydrodynamics, and nucleation dynamics, a femto-nanosecond and nano-micrometer multiscale framework combining electron–phonon-coupled heat transfer, lattice deformation, phase transition, and plasma eruption was constructed to describe the heat and mass transfer mechanism of femtosecond laser–copper interaction. A multiphysics model was proposed in this study to simulate the ablation process with different laser fluences. Ablation occurs at low near-threshold fluences primarily via a combination of the thermal phase transition process of melting and thermoplastic deformation coupled with the nonthermal phase transition process of hot electron explosion. Marangoni convection and non-uniform nucleation at the solid–liquid interface create micro-nano structures on the surface of the ablation crater. At a high laser fluence, plasma plumes are emitted via gasification and eruption, and as the material is heated to decrease its density, the surface is broken into a micro-column structure, and then the micro-columns fracture and erupt to form micro-nano structures and plasma plumes. Numerical results offer a better understanding of surface topography modifications and plasma plume evolution and promote the application of femtosecond laser precision fabrication in the fields of aviation, mechanics, electronics, and materials engineering.

Chiral nanomaterials have drawn extensive attention on account of numerous application prospects in optoelectronics, asymmetric catalysis, chiral recognition, and three-dimensional (3D) display. Thereinto, chiral perovskite has been a hotspot due to brilliant optoelectronic properties, but some problems limit the development, including low quantum yield, low chiral intensity, and the lack of facile regulation. To overcome these issues, an effective ligand exchange strategy

SUMMARY: Resveratrol is a polyphenol known to have many beneficial biological activities. In our study, we investigated the effect of supplementing chicken feed with different concentrations of resveratrol. A total of 2,160 Jingfen white egg chickens in their 210-d old were selected for this study. They were randomly distributed into 4 diet groups with 6 replicates each. Each replicate group contained 90 chickens. Diets were supplemented with 1 of 4 doses of resveratrol: 0, 200, 400, and 800 mg/kg. Relative to that in controls, the egg production rate and mean daily food intake significantly increased upon 200 mg/kg resveratrol treatment (P < 0.05). The feed-to-egg ratio also significantly diminished in these animals (P < 0.05), as did the cull/death rate. Resveratrol was also linked with extended egg shelf lives and improved sensory scores. Supplementation with 400 mg/kg resveratrol significantly reduced levels of total serum cholesterol and triglycerides and activities of alanine transaminase and aspartate transaminase (P < 0.05). These results therefore show that 200 mg/kg resveratrol supplementation improved the performance of laying hens, whereas 400 mg/kg dose was associated with better lipid metabolism, reduced egg cholesterol content, extended egg shelf life, improved antioxidant activity, and improved egg sensory scores.

FeI2(CO)3PPh3, which usually used as the precursor of [Fe]-hydrogenase, was firstly used as catalyst in one-step hydroxylation of phenol to dihydroxybenzenes. It was found that the reaction can be conducted smoothly in aqueous phase at ambient temperature (25 °C). In the optimum conditions, the conversion of phenol is 26.7% and selectivity of DHB is 80.0%. The possible mechanism was investigated and proposed. The apparent kinetics study shows that it is a pseudo second order reaction and activation energy Ea is 66.36 kJ/mol.

Ligand-induced chirality in core/shell nanocrystals (NCs) has attracted extensive attention because of many valuable potential applications. However, the cause of chirality especially in semiconduc...

This study aimed to evaluate the variation of milk mineral and chemical components in colostrum and milk corresponding to milking time and lactation day. Samples were collected at 1, 7, 14 and 21 d...

New ordered architectures or morphologies could be obtained through the self-assembly process and usually generate new physical and chemical properties. Here we report an adjustable self-assembly research study on copper sulphide nanocrystals (Cu1.94S NCs) forming five kinds of plant-like morphologies. Hydrophobic Cu1.94S quantum dots were prepared in the CHCl3 phase and transferred to the aqueous phase and capped with cysteine or penicillamine through a ligand exchange technique. Afterwards, a facile and eco-friendly self-assembly process (without using any template or surfactant) was employed. Through regulating the conditions including the solvent composition, surface ligand and starting concentration of Cu1.94S NCs, five delicate architectures were obtained. In addition, the possible formation process and growth mechanism of the obtained three-dimensional (3D) Cu1.94S architectures was also proposed and discussed. The assembled Cu1.94S architectures show improved molar extinction coefficients compared with individual Cu1.94S NCs, and in this way, better photothermal performance is achieved.

Different fusiform-shaped MIL-88A materials were successfully prepared by adjusting the mole ratio of the central metal ion and the organic ligand and using different polar solvents. With differently shaped MIL-88A supports, several Ag/AgCl@MIL-88A (ACML) were prepared successfully using the in situ growth method. These ACML composites showed a good photocatalytic activity under the simulated sunlight and visible light. The employment of Cl− ions, anchored on the surface of MIL-88A, could improve the dispersion and stability of the loaded Ag/AgCl nanoparticles. The s-ACML composite showed excellent photocatalytic stability during the cycle tests. The in situ growth strategy provided a facile method to design and synthesize MOF composite photocatalysts for wastewater treatment. In addition, based on the related optical and electrical characterization analysis, a possible mechanism of the ACML composite photocatalytic activity was proposed.

The effect of

Chiral semiconductor nanomaterials induced by capped chiral ligands are of great interest for both theoretical studies and advanced applications. In this study, CdTe/CdSe quantum dots (QDs), defined as type-II core/shell nanostructure, with the advantage of a good separation of holes and electrons are imparted chirality with L/D-cysteine and L/D-penicillamine molecules. Circular dichroism (CD) at exciton transitions from cysteine- and penicillamine-capped QDs is different in shape and intensity. CD intensities decrease with increasing shell thickness from three monolayers to six monolayers, indicating a decreased hybridization degree between the holes in CdTe core and the electrons in chiral ligands. Elevated cysteine concentration leads to decreased g-factor, probably due to an altered binding mode from tridentate to bidentate. Our observations provide further insights into the understanding of chiral phenomenon as well as optimized design and applications of chiral nanostructures.

A novel [FeFe]-hydrogenase biomimetic catalyst [(μ-dmedt)Fe2(CO)5](μ-DPPF-O) (1) was prepared by CO-substitution in the (μ-dmedt)[Fe2(CO)6] complex with DPPF in THF. Confirmation of the catalyst structure was determined by FTIR, 1H NMR, 13C NMR, 31P NMR and single crystal X-ray diffraction. Complex 1 exhibited better catalytic reactivity for phenol hydroxylation than the all-carbonyl complex (μ-dmedt)[Fe2(CO)6]. The dihydroxybenzene selectivity of 94.0% and phenol conversion of 42.9% were obtained under the optimal reaction conditions. The relationships between electron density of the Fe Fe bond and the catalytic activity of these complexes were revealed, which showed that the more electron rich the Fe Fe bond is, the better catalytic hydroxylation activity was achieved.

Graphitic carbon nitride (g-C3N4) has attracted enormous attention in photocatalysis owing to its special structure and properties. The insufficient light absorption and fast charge-carrier recombination limit its further photocatalytic application. Herein, we report a facile approach to fabrication of the g-C3N4 modified simultaneously with phosphorus and proton by directly heating the mixture of urea phosphate (UP) and urea in air. The incorporation of the phosphorus atoms in g-C3N4 can significantly decrease the band gap, leading to the enhanced light absorption efficiency. Furthermore, UP can also introduce the protons to the structure of g-C3N4 from protonation. The protons can inhibit the recombination of the charge carriers and improve their utilization. The synergistic effect of the phosphorus doping and protonation in g-C3N4 results in the superior visible-light photocatalytic performance for both degradation of Rhodamine B (RhB) and H2 evolution from water splitting. We believe that our findings...

Location-based social apps, such as Skout, have been widely used by millions of users for sharing their location information. In this work, we collected all the location information published by over 1.2 million Skout users during December 2012 and June 2016. Based on the collected information, we model the inter-city mobility of Skout users with a global city network, and analyze the evolution of the network based on its structural characteristics. Moreover, we look into Skout users’ mobility patterns by discovering the most popular inter-city routes, destinations, and tightly connected city groups, and analyze the impact on the mobility patterns from geographical distances, languages and cultures. Finally, we leverage machine learning techniques to build a model for identifying the most influential cities in the world according to the Skout data. The results are able to assist individuals, governors and business leaders in making better decisions regarding traveling, immigrating, measuring city improvements and cooperation with cities.

An ingenious method was employed to design and fabricate the TiO2/g-C3N4 heterojunction photocatalysts in this study. The thermal oxidation etching of g-C3N4 nanosheets and the in situ growth of TiO2 nanocrystal on the surface of g-C3N4 nanosheets were completed simultaneously by the calcination process. The g-C3N4 nanosheets played a crucial role in regulating and assembling the structures and morphologies of TiO2. Furthermore, the thickness and content of g-C3N4, and the crystallinity of TiO2 in TiO2/g-C3N4 composites could be regulated and controlled by the calcination temperature. Among the resultant TiO2/g-C3N4 samples, the TiO2/g-C3N4 sample with 41.6 wt% g-C3N4 exhibited the highest photocatalytic activity. It could degrade almost all MO molecules under visible light irradiation within 3 h. Moreover, it displayed higher visible light photocatalytic performance for degrading MO solution than pure g-C3N4 and D-TiO2. The synergistic effect between TiO2 and g-C3N4 makes significant contributions to the enhancement of the visible light photocatalytic activity. In addition, the favorable photocatalytic performance of TiO2/g-C3N4 nanocomposites is also attributed to the porous structures and uniform morphologies, and large surface area. Furthermore, the resultant TiO2/g-C3N4 exhibits excellent photocatalytic stability. Radical trapping experiments indicated that O2− and h+ were the main reactive species during the photodegradation process under visible light irradiation. Hopefully, the results can offer new design and strategy for preparing other g-C3N4-based nanocomposites for environmental and energy applications.

Tubular structure TiO2/C/TiO2 hybrids were successfully fabricated via impregnation-calcination method. A castoff of tubular structure FCT (the fluff of the chinar tree) was employed as template and carbon source, and economical TiCl4 was purchased as titanium source. In particular, the outer tube wall of the TiO2/C/TiO2 hybrid was constructed with interlaced and curly nanofibers. Nevertheless, the inner tube wall was assembled with spheroid-likely TiO2 nanoparticles. In addition, the graphitic carbon layer was formed between TiO2 nanofibers and nanoparticles. The FCT played a vital role in inducing and assembling the hierarchical tube structure of the TiO2/C/TiO2 hybrid. Furthermore, the design of the hydrolysis reaction during the preparation process also made contributions on building the unique structure. The hydrolysis reaction was taken place by blowing atmosphere, which could control the hydrolysis reaction at an appropriate reaction rate. Furthermore, the graphitic C layer in the TiO2/C/TiO2 hybrid could accelerate the migration and separation of the photogenerated electron during the reaction process. At appropriate carbon content, the TiO2/C/TiO2 could degrade 99% tetracycline hydrochloride (TH) under simulated sunlight irradiation within 30 min.

To probe the influence of phosphine ligand substitution on the well-known [2Fe2S] model, two new [FeFe]-hydrogenase model complexes with the phosphine ligands, PMe3 or P(CH3O)3, were synthesized, such as μ-(SCH(CH2CH3)CH2S)–Fe2(CO)5PMe3 1, and μ-(SCH(CH2CH3)CH2S)–Fe2(CO)5P(CH3O)3 2 Confirmation of structures was provided by FTIR, 1H NMR, 13C NMR, 31P NMR, elemental analyses and single-crystal X-ray analysis. The crystal structure of complex 2 shows that the P(CH3O)3 ligand has less steric effect on the coordination geometry of the Fe atom than the PMe3 ligand. In the presence of HOAc in CH3CN solution, the hydrogen evolution overpotentials of complexes 1 and 2 were 0.91 V and 0.81 V, respectively. Comparatively, complex 2 produces hydrogen at an overpotential of 0.1 V, lower than that for complex 1. A further electrocatalytic study showed the maximum charges for 1 and 2 were 31.3 mC and 56.3 mC at −2.30 V for 10 min, respectively. These studies showed that the complexes 1 and 2 have the ability, as novel electrocatalysts, for catalysis of hydrogen production, and complex 2 has better electrocatalytic ability than complex 1.