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Stimuli-responsive nanotheranostics have been widely explored for precision medicine. Here, we developed a pH/light dual-stimuli-responsive nanotheranostic agent for biological/physical dual-targeting photothermal-enhanced chemotherapy of U87MG tumor. This nanotheranostic agent was composed of the RGD (Arg-Gly-Asp) peptide, melanin-coated magnetic nanoparticles (MMNs), doxorubicin (DOX), and indocyanine green (ICG), denoted as RMDI. The tumor accumulation of RMDI was simultaneously improved through biological active targeting by RGD and physical magnetic targeting by an external magnetic field at tumor tissues, which was proven by in vivo photoacoustic/magnetic resonance/fluorescence (PA/MR/FL) trimodal imaging. Under dual stimuli of the tumor acidic microenvironment and laser irradiation, both DOX and ICG were released in a controlled fashion, demonstrating impressive therapeutic outcomes against U87MG tumor both in vitro and in vivo, respectively. Owing to the synergistic photothermal/chemotherapy, the dual-stimuli-responsive and dual-targeting nanotheranostic agent completely ablated U87MG tumor in vivo without any tumor recurrence and biotoxicity. This nanotheranostic agent exhibited great potential in multimodal imaging-guided synergistic therapy of cancer.

Design and engineering of bifunctional catalysts are critical in the development of electrochemical full water splitting. In this study, 4-ethylphenylacetylene-functionalized iridium (Ir–C≡, 1.7 ± ...

By utilizing a supramolecular complex rather than an individual molecule as a deformable and elastic substitutional component, we put forward a solid-solution strategy and demonstrate an example of how two related yet non-isostructural crystalline host-guest compounds can form molecular solid solutions. Interestingly, such a strategy can effectively and continuously modulate the molecular motion and phase transition in them, as revealed by the variable-temperature/frequency dielectric responses.

Owing to the powerful self-attention mechanism, the Transformer network has achieved considerable successes across many sequence modeling tasks and has become one of the most popular methods in text-to-speech (TTS). The vanilla self-attention excels in capturing long-range dependencies but suffers in modeling stable short-range dependencies that are quite important for speech synthesis where the local audio signals are highly correlated. To address this problem, we propose the hybrid lightweight convolution (HLC), which is responsible for fully exploiting local structures of a sequence, and combine it with the self-attention to improve the Transformer-based TTS. The experimental results show that our modified model obtains better performance in both objective and subjective evaluations. At the same time, we also demonstrate that a more compact TTS model may be built through the combination of self-attention and proposed hybrid lightweight convolution. Besides, this method is also potentially adaptable for other sequence modeling tasks.

To fabricate efficient multifunctional electrocatalysts for energy storage and conversion is still a great challenge, due to the difficulty in precisely identifying and regulating catalytic active sites. Herein, a series of isostructural metal–organic frameworks (MOFs) with V-shaped trinuclear clusters was used as an ideal model to investigate the activity of trifunctional electrocatalysis for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), as these clusters contain both coordination unsaturated metal sites (also known as open metal sites, OMSs) and coordination saturation metal sites (CSMSs), corresponding to both ends and the middle of the V-shaped cluster, respectively. Using a combination of single-crystal X-ray diffractometry, Mossbauer spectroscopy and theoretical calculations, the accurate metal sequence of trinuclear clusters and the regulation effect of the active sites were identified, revealing that the adjacent inactive site plays a significant role in regulating the catalytic performance of the endmost active site. The proposed model of metal cluster-based electrocatalysts facilitates the investigation on efficient multifunctional electrocatalysts as well as the related catalytic mechanisms.

As a major component of greenhouse gases (GHGs), excessive CO2 emissions have led to a series of environmental issues. Therefore, CO2 capture and storage (CCS) have attracted extensive attention from both fundamental and practical research communities. However, traditional adsorbents and catalysts still have many defects in CO2 capture and transformation. In recent years, nanomaterials have been considered as promising adsorbents for CO2 capture due to their high adsorption capacity, low cost and wide availability. This review article describes the main technologies used for CO2 capture, highlights the latest research status of nanomaterials for CO2 capture, and investigates the influence of surface microstructure and modification of materials on CO2 capture ability. Although many new nanomaterials and capture technologies have been developed, the high cost and the low technology scale of CO2 capture remain major obstacles. Future research should focus on designing low-cost, high-availability nanomaterials to reduce CO2 emission from large-scale power plants.

Atomically thin two-dimensional (2D) materials exhibit enormous potential in photodetectors because of novel and extraordinary properties, such as passivated surfaces, tunable bandgaps, and high mobility. High-performance photodetectors based on 2D materials have been fabricated for broadband, position, polarization-sensitive detection, and large-area array imaging. However, the current performance of 2D material photodetectors is not outstanding enough, including response speed, detectivity, and so forth. The way to further promote the development of 2D material photodetectors and their corresponding practical applications is still a tremendous challenge. In this article, these issues of 2D material photodetectors are analyzed and expected to be solved by combining micro-nano characterization technologies. The inherent physical properties of 2D materials and photodetectors can be accurately characterized by Raman spectroscopy, transmission electron microscopy (TEM), and scattering scanning near-field optical microscope (s-SNOM). In particular, the precise probe of lattice defects, doping concentration, and near-field light absorption characteristics can promote the researches of low-noise and high-responsivity photodetectors. Scanning photocurrent microscope (SPCM) can show the overall spatial distribution of photocurrent and analyze the mechanism of photocurrent. Photoluminescence (PL) spectroscopy and Kelvin probe force microscope (KPFM) can characterize the material bandgap, work function distribution and interlayer coupling characteristics, making it possible to design high-performance photodetectors through energy band engineering. These advanced characterization techniques cover the entire process from material growth, to device preparation, and to performance analysis, and systematically reveal the development status of 2D material photodetectors. Finally, the prospects and challenges are discussed to promote the application of 2D material photodetectors.

Photocatalytic reduction of CO2 to value-added fuels is a promising route to reduce global warming and enhance energy supply. However, poor selectivity and low efficiency of catalysts are usually the limiting factor of their applicability. Herein, a photoinduction method was developed to achieve the formation of Cu single atoms on a UiO-66-NH2 support (Cu SAs/UiO-66-NH2) that could significantly boost the photoreduction of CO2 to liquid fuels. Notably, the developed Cu SAs/UiO-66-NH2 achieved the solar-driven conversion of CO2 to methanol and ethanol with an evolution rate of 5.33 and 4.22 μmol h-1 g-1, respectively. These yields were much higher than those of pristine UiO-66-NH2 and Cu nanoparticles/UiO-66-NH2 composites. Theoretical calculations revealed that the introduction of the Cu SAs on the UiO-66-NH2 greatly facilitates the conversion of CO2 to CHO* and CO* intermediates, leading to excellent selectivity toward methanol and ethanol. This study provides new insights for designing high-performance catalyst for photocatalytic reduction of CO2 at the atomic scale.

Metal–organic frameworks (MOFs) are increasingly being investigated as electrocatalysts for the oxygen evolution reaction (OER). Despite their promising catalytic activity, many fundamental questions concerning their structure−performance relationships—especially those regarding the roles of active species—remain to be answered. Here we show the structural transformation of a Ni0.5Co0.5-MOF-74 during the OER by operando X-ray absorption spectroscopy analysis and high-resolution transmission electron microscopy imaging. We suggest that Ni0.5Co0.5OOH0.75, with abundant oxygen vacancies and high oxidation states, forms in situ and is responsible for the high OER activity observed. The ratio of Ni to Co in the bimetallic centres alters the geometric and electronic structure of as-formed active species and in turn the catalytic activity. Based on our understanding of this system, we fabricate a Ni0.9Fe0.1-MOF that delivers low overpotentials of 198 mV and 231 mV at 10 mA cm−2 and 20 mA cm−2, respectively. Metal–organic frameworks (MOFs) are increasingly being explored for electrocatalytic oxygen evolution, which is half of the water splitting reaction. Here the authors show that, under reaction conditions, mixed metal oxyhydroxides form at the nodes of bimetallic MOFs, which are highly catalytically active.

Porous molecular crystals sustained by hydrogen bonds and/or weaker connections are an intriguing type of adsorbents, but they rarely demonstrate efficient adsorptive separation because of poor structural robustness and tailorability. Herein, we report a porous molecular crystal based on hydrogen-bonded cyclic dinuclear AgI complex, which exhibits exceptional hydrophobicity with a water contact angle of 134°, and high chemical stability in water at pH 2-13. The seemingly rigid adsorbent shows a pore-opening or nonporous-to-porous type butane adsorption isotherm and complete exclusion of isobutane, indicating potential molecular sieving. Quantitative column breakthrough experiments show slight co-adsorption of isobutane with an experimental butane/isobutane selectivity of 23, and isobutane can be purified more efficiently than for butane. In situ powder/single-crystal X-ray diffraction and computational simulations reveal that a trivial guest-induced structural transformation plays a critical role.

The chain-like carbon nanotubes (CNTs) decorated with CoFeB (CoFeB/CNTs) prepared by oxidation-reduction method is introduced into MgH2 to facilitate its hydrogen storage performance. The addition of CoFeB/CNTs enables MgH2 to start desorbing hydrogen at only 177 °C. Whereas pure MgH2 starts hydrogen desorption at 310 °C. The dehydrogenation apparent activation energy of MgH2 in CoFeB/CNTs doped-MgH2 composite is only 83.2 kJ/mol, and this is about 59.5 kJ/mol lower than that of pure MgH2. In addition, the completely dehydrogenated MgH2−10 wt% CoFeB/CNTs sample can start to absorb hydrogen at only 30 °C. At 150 °C and 5 MPa H2, the MgH2 in CoFeB/CNTs doped-MgH2 composite can absorb 6.2 wt% H2 in 10 min. The cycling kinetics can remain rather stable up to 20 cycles, and the hydrogen storage capacity retention rate is 98.5%. The in situ formation of Co3MgC, Fe, CoFe and B caused by the introduction of CoFeB/CNTs can provide active and nucleation sites for the dehydrogenation/rehydrogenation reactions of MgH2. Moreover, CNTs can provide hydrogen diffusion pathways while also enhancing the thermal conductivity of the sample. All of these can facilitate the dehydrogenation/rehydrogenation performance and cyclic stability of MgH2.

Electrocatalysis of four-electron oxygen reduction reaction (ORR) provides a promising approach for energy transfer, storage and oxygen monitoring. However, it is always accompanied by the reductio...

Nanobubble is a rising research field, which attracts more and more attentions due to its potential applications in medical science, catalysis, electrochemistry and etc. To better implement these applications, it is urgent to understand one of the most important mechanisms of nanobubbles, the evolution. However, few attentions have been paid in this aspect because of the methodology difficulties. Here we successfully used dark-field microscopy to study the evolution process of single nanobubbles generated from formic acid dehydrogenation on single Pd-Ag nanoplates. We found some of the nanobubbles in this system can exhibit three distinct states representing different sizes, which can transform among each other. These transitions are not direct but through some intermediate states. Further kinetic analysis reveals complicated mechanisms behind the evolution of single nanobubbles. The results acquired from this study can be applicable to nanobubble systems in general and provide insights into the understanding of mechanisms affecting the stability of nanobubbles and their applications.

Molecular simulation was used to investigate the coadsorption mechanism of Na+ and H2O on the hydroxylated silicon wafer. Water molecules can form a 3.5 A-thickness bimolecular structure at the sol...

Weak van der Waals interactions between interlayers of two-dimensional layered materials result in disabled across-interlayer electron transfer and poor layered structural stability, seriously deteriorating their performance in energy applications. Herein, we propose a novel covalent assembly strategy for MoS2 nanosheets to realize unique MoS2 /SnS hollow superassemblies (HSs) by using SnS nanodots as covalent linkages. The covalent assembly based on all-inorganic and carbon-free concept enables effective across-interlayer electron transfer, facilitated ion diffusion kinetics, and outstanding mechanical stability, which are evidenced by experimental characterization, DFT calculations, and mechanical simulations. Consequently, the MoS2 /SnS HSs exhibit superb rate performance and long cycling stability in lithium-ion batteries, representing the best comprehensive performance in carbon-free MoS2 -based anodes to date. Moreover, the MoS2 /SnS HSs also show excellent sodium storage performance in sodium-ion batteries.

Mafic magmatism within deep crustal hot zones plays an important role in the crustal formation and evolution. High-pressure garnet crystallization drives magma differentiation and Fe isotope fractionation at the base of the lower crust. The ∼840 Ma intrusion and the associated ∼830 Ma dikes from the Tongde region in South China consist mainly of gabbro and diorite, which record complicated magmatic processes of the deep crustal zones and provide new insights into the Fe isotope fractionation. Rocks from the Tongde intrusion have high Sr/Y ratios (61–163) and variable δ57Fe values (+0.07 to +0.21‰ relative to IRMM-014) that initially increase then decrease with progressive magmatic differentiation. All samples do not display obvious imprint of deuteric fluid exsolution, and residual garnet in the mantle source did not fractionate the Fe isotope compositions of the primary magmas significantly. The variable Fe isotope signatures in this study can be reproduced by sequential fractional crystallization of olivine/pyroxene and garnet in the deep crust followed by amphibole saturation in the upper section. The host rocks of the intrusion underwent diffusive exchange with the dikes. Removal of both isotopically light- and heavy-Fe minerals well explains the small Fe isotope fractionation in mafic and intermediate rocks. The high-Sr/Y suites of the intrusion and dikes have an average δ57Fe of +0.11 ± 0.02‰ (2SD), similar to the value of arc crust at convergent continental margins. Therefore, garnet fractionation is an important process in arc roots, which drives the melts evolving to calc-alkaline series. Fractional crystallization of hydrous basaltic magmas under high pressures in deep crustal hot zones makes a significant contribution to the formation and evolution of continental crust.

In this article, we present the American option pricing procedure based on the binomial tree from an imprecise statistical aspect. Nonparametric Predictive Inference (NPI) is implemented to infer imprecise probabilities of underlying asset movements, reflecting uncertainty while learning from data, which is superior to the constant risk-neutral probability. In a recent article, we applied the NPI method to the European option pricing procedure that gives good results when the investor has non-perfect information. We now investigate the NPI method for American option pricing, of which imprecise probabilities are considered and updated for every one-time-step path. Different from the classic models, this method is shown that it may be optimal to early exercise an American non-dividend call option because our method considers all information that occurs in the future steps. We also study the performance of the NPI pricing method for American options via simulations in two different scenarios compared to the Cox, Ross and Rubinstein binomial tree model (CRR), first where the CRR assumptions are right, and second where the CRR model uses wrong assumptions. Through the performance study, we conclude that the investor using the NPI method tends to achieve good results in the second scenario.

Multimodal cancer synergistic therapy exhibited remarkable advantages over monotherapy in producing an improved therapeutic efficacy. In this work, Janus-type γ-Fe2O3/SiO2 nanoparticles (JFSNs) are conjugated with glucose oxidase (GOx) for synergistic cancer starvation/chemodynamic therapy. The γ-Fe2O3 hemisphere of JFSNs can perform photoacoustic/T2 magnetic resonance dual-modal imaging of tumors. GOx on the surface of JFSNs catalyzes the decomposition of glucose and produces H2O2 for cancer starvation therapy. Subsequently, the γ-Fe2O3 hemisphere catalyzes the disproportionation of H2O2 to generate highly reactive hydroxyl radicals in an acidic tumor microenvironment. The close distance between GOx and JFSNs ensures adequate contact between the γ-Fe2O3 hemisphere and its substrate H2O2, thus enhancing the catalytic efficiency. This synergy of glucose depletion, biotoxic H2O2 and hydroxyl radicals significantly suppresses 4T1 mammary tumor growth with minimal adverse effects.

Metal–nitrogen–carbon (MNC) nanocomposites have been hailed as promising and efficient electrocatalysts toward oxygen reduction reaction (ORR), due to the formation of MNx coordination moieties. Ho...

A novel fluorinated biphenyldicarboxylate ligand of 3,3',5,5'-tetrafluorobiphenyl-4,4'-dicarboxylic acid (H2-TFBPDC) and its terbium metal-organic framework, {[Tb2(TFBPDC)3(H2O)]·4.5DMF·0.5H2O}n (denoted as JXNU-6), were synthesized. JXNU-6 exhibits a three-dimensional (3D) framework built from one-dimensional (1D) terbium carboxylate helical chains bridged by TFBPDC2- linkers. The 3D framework of JXNU-6 features 1D fluorine-lined channels. The gas adsorption experiments show that the activated JXNU-6 (JXNU-6a) displays distinct adsorption behavior for propyne (C3H4) and propylene (C3H6) gases. The effective removal of a trace amount of C3H4 from C3H6 was achieved by JXNU-6a under ambient conditions, which is demonstrated by the column-breakthrough experiments. The modeling studies show that the preferential binding sites for C3H4 are the exposed F atoms on the pore surface in 1D channels. The strong C-H···F hydrogen bonds between C3H4 molecules and F atoms of TFBPDC2- ligands dominate the host-guest interactions, which mainly account for the excellent C3H4/C3H6 separation performance of JXNU-6a. This work provides a strategy for specific recognition toward C3H4 over C3H6 through the C-H···F hydrogen bond associated with the fluorinated organic ligand.

The production of lactic acid (LaA) directly from actual biomass via a one-step reaction without pretreatment by chemocatalysis has shown high potential for satisfying its enormous demand in widesp...

A new, one-pot method for the synthesis of 4H-3,1-benzoxazine derivatives has been developed. The Passerini-azide reactions of 2-azidobenzaldehydes, trimethylsilyl azide, and isocyanides produced azide intermediate without separation, which then reacted with isocyanides to give 4H-3,1-benzoxazine derivatives via a tandem one-pot palladium-catalyzed azide–isocyanide coupling/cyclization reaction in moderate to good yields.

Metal-free energetic materials generally have the advantages of high gas yield and metal-free residue after combustion or explosion, enabling them to be widely used as explosives and propellant com...

In order to improve the hydrogen storage performance of MgH2, graphene and CeF3 co-catalyzed MgH2 (hereafter denoted as MgH2+CeF3@Gn) were prepared by wet method ball milling and hydriding, which is a simple and time-saving method. The effect of CeF3@Gn on the hydrogen storage behavior of MgH2 was investigated. The experimental results showed that co-addition of CeF3@Gn greatly decreased the hydrogen desorption/absorption temperature of MgH2, and remarkably improved the dehydriding/hydriding kinetics of MgH2. The onset hydrogen desorption temperature of Mg + CeF3@Gn is 232 °C，which is 86 °C lower than that of as-milled undoped MgH2, and its hydrogen desorption capacity reaches 6.77 wt%, which is 99% of its theoretical capacity (6.84 wt%). At 300 °C and 200 °C the maximum hydrogen desorption rates are 79.5 and 118 times faster than that of the as-milled undoped MgH2. Even at low temperature of 150 °C, the dedydrided sample (Mg + CeF3@Gn) also showed excellent hydrogen absorption kinetics, it can absorb 5.71 wt% hydrogen within 50 s, and its maximum hydrogen absorption rate reached 15.0 wt% H2/min, which is 1765 times faster than that of the undoped Mg. Moreover, no eminent degradation of hydrogen storage capacity occurred after 15 hydrogen desorption/absorption cycles. Mg + CeF3@Gn showed excellent hydrogen de/absorption kinetics because of the MgF2 and CeH2-3 that are formed in situ, and the synergic catalytic effect of these by-products and unique structure of Gn.

We for the first time report that the activated CRISPR-Cas12a system trans-cleaves DNA G-quadruplexes (G4). The cleavage activity on human telomere G4 and TBA G4 was investigated and verified by FRET, CD, gel electrophoresis and NMR. We believe that this finding will pave a new avenue for advancing the applications of CRISPR-Cas12a and G4 in biosensing and biochemistry.

Iron single atom catalysts have emerged as one of the most active electrocatalysts towards the oxygen reduction reaction (ORR), but the unsatisfactory durability and limited activity for the oxygen evolution reaction (OER) has hampered their commercial applications in rechargeable metal–air batteries. By contrast, cobalt-based catalysts are known to afford excellent ORR stability and OER activity, due to the weak Fenton reaction and low OER Gibbs free energy. Herein, a bimetal hydrogel template is used to prepare carbon aerogels containing Fe–Co bimetal sites (NCAG/Fe–Co) as bifunctional electrocatalysts towards both ORR and OER, with enhanced activity and stability, as compared to the monometal counterparts. High-resolution transmission electron microscopy, elemental mapping and X-ray photoelectron spectroscopy measurements demonstrate homogeneous distributions of the metal centers within defected carbon lattices by coordination to nitrogen dopants. X-ray absorption spectroscopic measurements, in combination with other results, suggest the formation of FeN3 and CoN3 moieties on mutually orthogonal planes with a direct Fe–Co bonding interaction. Electrochemical measurements show that NCAG/Fe–Co delivers a small ORR/OER potential gap of only 0.64 V at the current density of 10 mA cm−2, 60 mV lower than that (0.70 V) with commercial Pt/C and RuO2 catalysts. When applied in a flexible Zn–air battery, the dual-metal NCAG/Fe–Co catalyst also shows a remarkable performance, with a high open-circuit voltage of 1.47 V, a maximum power density of 117 mW cm−2, as well as good rechargeability and flexibility. Results from this study may offer an ingenious protocol in the design and engineering of highly efficient and durable bifunctional electrocatalysts based on dual metal-doped carbons.

A series of bisthiazole-based hydroxamic acids as novel potent HDAC inhibitors was developed during our previous work. In the present work, a new series of highly potent bisthiazole-based compounds were designed and synthesized. Among the prepared compounds, compound H13, which contains an α-(S)-methyl-substituted benzyl group, displays potent inhibitory activity toward human HDACs and several cancer cells lines. Compound H13 has a favorable PK profile and high tissue distribution specificity in the colon, as well as good efficacy in the AOM-DSS mouse model for colitis-associated colonic tumorigenesis.

The photostability of DNA plays a key role in the normal function of organisms. A-5FU is a base pair derivative of the A-T dimer where the methyl group is replaced by a F atom. Here, accurate static TDDFT calculations and non-adiabatic dynamic simulations are used to systematically investigate the excited-state decay paths of the A-5FU dimer related to the proton transfer and the out-of-plane twisting deformation motion of A and 5FU in the 1ππ* and 1nπ* states. CC2 is used to check the accuracy of the current TDDFT calculations. Our results show that the deformation of the C[double bond, length as m-dash]C or C[double bond, length as m-dash]N double bond in A and 5FU provides an efficient pathway for the depopulation of the lowest excited states, which can compete with the excited-state proton transfer paths in the dimer. This finding indicates that monomer-like decay paths could be important for the photostability of weakly hydrogen-bonded DNA base pairs and provide a new insight into the excited-state decay paths in base pairs and their analogues.

A novel metal-organic framework (MOF) of [Co8(OH)4(TCA)4(H2O)4]n (abbreviation: JXNU-9) based on the unique octanuclear Co8(μ3-OH)4 clusters linked by 4,4',4″-nitrilotribenzoate (TCA3-) ligands featuring small caged structures and one-dimensional channels was prepared and characterized. JXNU-9 shows a high C2H6 uptake capacity of 3.60 mmol g-1 (4.46 mmol cm-3) at 298 K and 1 atm with a small isosteric heat of adsorption (23.6 kJ mol-1) and a moderate C2H6/C2H4 adsorption selectivity of 1.7, resulting in excellent C2H6/C2H4 separation performance. The pore walls decorated by plenty of aromatic rings provide π-electron-cloud-surrounding environments to accommodate the large polarizable C2H6 molecules. The calculations demonstrate that the rich π-systems in JXNU-9 facilitate an adsorption affinity for large C2H6 molecules through multiple C-H···π interactions. Additionally, the open metal sites located in the concave pores with a close Co···Co separation (4.21 A) in octanuclear Co8(μ3-OH)4 clusters make the open metal sites inaccessible for the C2H4 molecule with a kinetic diameter of 4.163 A. Thus, the annihilation of open metal sites in this structure is achieved, which further facilitates the C2H6-selective C2H6/C2H4 separation.

Materials demonstrating unusual large positive and negative thermal expansion are fascinating for their potential applications as high-precision microscale actuators and thermal expansion compensators for normal solids. However, manipulating molecular motion to execute huge thermal expansion of materials remains a formidable challenge. Here, we report a single-crystal Cu(II) complex exhibiting giant thermal expansion actuated by collective reorientation of imidazoliums. The circular molecular cations, which are rotationally disordered at a high temperature and statically ordered at a low temperature, demonstrate significant reorientation in the molecular planes. Such atypical molecular motion, revealed by variable-temperature single crystal X-ray diffraction and solid-state NMR analyses, drives an exceptionally large positive thermal expansion and a negative thermal expansion in a perpendicular direction of the crystal. The consequent large shape change (~10%) of bulk material, with remarkable durability, suggests that this complex is a strong candidate as a microscale thermal actuating material., Designing materials with large thermal expansion is highly desirable to fabricate microscale devices. The authors report unusually large anisotropic negative and positive thermal expansion in a simple crystalline material, through temperature-driven orientation of imidazole cations acting as molecular wheels.

The confinement effect has been proposed to explain the enhanced catalytic activity for chemical reactions inside the metal organic framework-based composites; however, the exact mechanism remains ...

The sluggish nature of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) coupled with the high cost of related noble-metal catalysts stimulate the research of active non-noble met...

Rational design and precise fabrication of catalysts with high active site exposure and efficient charge transport are highly desirable but challenging. Herein, we report a unique strategy to construct well-defined and mixed-dimensional W17O47-MoS2 heterostructures, where ultrathin MoS2 nanolayers vertically rooted onto W17O47 nanowires in edge-contact geometry. The in situ etching approach simultaneously created high accessible anion-deficit sites for refined electronic structures and intimate heterointerface for spatial charge-flow-steering. The best W17O47-MoS2, with optimized MoS2 loading, exhibited a MoS2 mass activity 116-fold higher than that of pure MoS2 in electrocatalytic hydrogen evolution reaction. Density functional theory calculations unveiled that low-coordination sites and intimate interfaces induced the synergy of interface-O and edge-Mo atoms, substantially regulating the electron distribution of active sites in the critical hydrogen activation step. This work not only provided a platform for understanding the origin of catalytic activity, but also brought instructive design criteria for constructing heterostructures in catalysis, photonics, and electronics.

Molecular sieving can lead to ultrahigh selectivity and low regeneration energy because it completely excludes all larger molecules via a size restriction mechanism. However, it allows adsorption of all molecules smaller than the pore aperture and so separations of complicated mixtures can be hindered. Here, we report an intermediate-sized molecular sieving (iSMS) effect in a metal-organic framework (MAF-41) designed with restricted flexibility, which also exhibits superhydrophobicity and ultrahigh thermal/chemical stabilities. Single-component isotherms and computational simulations show adsorption of styrene but complete exclusion of the larger analogue ethylbenzene (because it exceeds the maximal aperture size) and smaller toluene/benzene molecules that have insufficient adsorption energy to open the cavity. Mixture adsorption experiments show a high styrene selectivity of 1,250 for an ethylbenzene/styrene mixture and 3,300 for an ethylbenzene/styrene/toluene/benzene mixture (orders of magnitude higher than previous reports). This produces styrene with a purity of 99.9%+ in a single adsorption-desorption cycle. Controlling/restricting flexibility is the key for iSMS and can be a promising strategy for discovering other exceptional properties.

Hydrogen production via water electrolysis is promising but impeded by sluggish cathodic and anodic reactions. Consequently, highly-efficient and earth-abundant electrocatalysts are attracting considerable attention. Herein we report a bifunctional Ni Mo alloy nanotube for efficient hydrogen production coupled with anodic urea oxidation in a hybrid water electrolysis system. Specifically, ultralow potentials of −44 mV and 1.36 V (vs. RHE) are required to deliver 10 mA cm−2 current density for cathodic and anodic reactions, respectively. Density functional theory (DFT) calculation results show the Mo center is the main reaction site for the chemisorption and O H bond cleavage of H2O while Ni center is identified as the hydrogen-evolving site. Based on this bifunctional Ni Mo electrocatalyst, a hybrid water electrolysis cell is proposed and the overall cell voltage of ∼1.43 V is achieved for outputting 10 mA cm−2 current density during the 10 h operation. The understandings in alternative electrode reactions coupled with highly-efficient and earth-abundant electrocatalysts for hybrid water electrolysis in this work holds encouraging potential in future energy conversion technologies and urea-related water treatments.

In this study, we obtained analytical solutions for functionally graded curved beams with different properties in tension and compression, in which the moduli of elasticity in tension and compression are assumed as two different exponential functions. First, by determining the unknown neutral layer, we established a simplified mechanical model concerning tension and compression subzone and derived the one-dimensional solution (i.e., the solution in the scope of mechanics of materials). Given that the one-dimensional solution is a relatively simplified one, thus a comprehensive understanding of this problem is still needed. For this purpose, we established the consistency equation expressed in terms of stress function under two-dimensional theory of elasticity. Combining boundary conditions of inner and outer edges with continuity conditions of the neutral layer, we applied power series method for the solution of stress components under pure bending. The variations of radial and circumferential stresses in different cases of bimodular functionally graded parameters are comprehensively analyzed with numerical examples. Results indicate that the position of the neutral layer is generally related to the elastic modulus and the functionally graded coefficients of the materials. Moreover, the maximum tensile or compressive bending stress may not take place at the outer or inner edges of the curved beam but inside the beam, which should be given more attention in the analysis and design of functionally graded curved beams with different properties in tension and compression.

Compound {(Me2NH2)3[Eu7(μ3-O)2(TBAPy)5(H2O)6]·12.5DMF}n (JXNU-5), constructed from the 1,3,6,8-tetrakis(4-carboxylphenyl)pyrene (TBAPy4–) ligand and one-dimensional (1D) europium carboxylate rods, is presented. JXNU-5 has a three-dimensional framework with 1D channels. The strong coordination bonds between EuIII ions with high charge densities and carboxylate O atoms as well as strong π···π-stacking interactions between pyrenes lead to a water-resistant JXNU-5, which was verified by powder X-ray diffraction and surface area measurements. The breakthrough simulations and experiments demonstrate that an efficient C2H2/CO2 (50/50 mixture) gas separation at ambient conditions was achieved with JXNU-5. The calculation results show that the dominating interactions between the absorbed C2H2 molecules and host framework are hydrogen bonds associated with the carboxylate O atoms exposed on the pores. Thus, an elegant example of a water-stable metal–organic framework for effective C2H2/CO2 separation is demonstrated.

Highly efficient and cost-effective bifunctional electrode materials are vital for both hydrogen and oxygen evolution reactions in water splitting. Assisting by the unique supercritical carbon dioxide (SC CO2) technique, NiFe2O4 nanoparticles are directly anchored on the vertically aligned carbon nanotubes (VACNT). The integrated hybrid electrocatalyst of NiFe2O4/VACNT demonstrates remarkable catalytic activities for both OER and HER. It requires overpotentials of only 240 mV and 150 mV to achieve 10 mA cm−2 anodic and cathodic current densities, respectively. Such excellent performance is credited to the synergistic effect raising from the interaction of tiny NiFe2O4 particles and VACNT, which provides highly exposed catalytic sites, fast charge transport, excellent reactant diffusion and interface infiltration. This work not only provides an effective technique to prepare efficient electrocatalyst for overall water splitting but also offers important understandings in nanostructure engineering for rational design functional materials in multidisciplinary application including energy conversion.

Fullerene (C60), the third carbon allotrope, has shown great potential in photoelectric materials and drug delivery. However, the low solubility of C60 in polar solvents, especially in water, is the major limiting factor for further applications. The use of ultrasound and amphiphilic block copolymers, poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG-b-P4VP), helped to disperse C60 in acidic aqueous solutions. As characterized by dynamic light scattering, transmission electron microscopy, and UV-visible spectroscopy, the C60 colloids had a core-shell structure with C60 aggregated in the micellar cores. The photosensitized generation of singlet oxygen using C60-bound polymer micelle was confirmed by the iodide method. More importantly, C60 and metalloporphyrin complexes could be synthesized by the self-assembly between PEG-b-P4VP/C60 micelle and metalloporphyrin. The stability of metalloporphyrin increased in the presence of the PEG-b-P4VP/C60 micelle. This study provides a method for the solubilization of C60 with many potential applications in biomedicals and photovoltaics.

Atomically thin nanomaterials have attracted tremendous research interest in the field of electrocatalysis as they expose a large fraction of surface atoms for the reaction. Previous works, however, have mainly focused on engineering surface electronic properties, which undoubtedly activates their inherent catalytic power, but is not representative when it comes to practical applications. In this work, we successfully control the assembled structure of atomically thin CoSe2 nanomaterials for water oxidation catalysis. The results show that the large nanobelt structure exhibits a low overpotential of 362.5 mV at 10 mA cm−2, a high current density of 34.2 mA cm−2 at 400 mV, a small Tafel slope of 57.6 mV dec−1, and excellent catalytic stability, significantly outperforming other assembled structures and previously reported results. The electrode constructed from large nanobelts possesses a porous structure with highly accessible channels that allows facile electrolyte diffusion and efficient mass transfer. In addition, the large nanobelts have better electronic contact with the current collector, which facilitates the charge transport and mass conversion processes. The manipulation of the assembled structure provides a new approach to the design of highly efficient catalysts for various reactions.

Through the combined techniques of variable-temperature X-ray structure analysis, dielectric measurement, isotope substitution and molecular dynamics simulation, we investigate a new supramolecular gyroscope (t-BuNH3)(18-crown-6)[ZnBr3(H2O)]. It undergoes an unusual isostructural phase transition, which is different to the non-isostructural one of the chlorine substituted analogue we reported previously. In addition, their solid solutions can be obtained, with a tunable phase transition temperature and the related properties. The comparative analysis of these homologous supramolecular gyroscopes provides in-depth insight for understanding the mechanism of the rarely observed temperature-induced isostructural phase transition as well as modulating the dipole rotation in crystals.

The surface reconstruction of cobalt phosphide nanosheets is investigated by an in situ electrochemical strategy for enhanced hydrogen evolution., Transition metal phosphides exhibit promising catalytic performance for the hydrogen evolution reaction (HER); however their surface structure evolution during electrochemical operation has rarely been studied. In this work, we investigate the surface reconstruction of CoP nanosheets by an in situ electrochemical activation method. After remodeling, CoP nanosheets experience an irreversible and significant evolution of the morphology and composition, and low-valence Co complexes consisting of Co(OH)x species are formed on the surface of CoP nanosheets, and they largely accelerate the dissociation of water. Benefiting from the synergistic effect of CoP and Co(OH)x, the working electrode shows a remarkably enhanced HER activity of 100 mV at 10 mA cm–2 with a Tafel slope of 76 mV dec–1, which is better than that of most transition metal phosphide catalysts. This work would provide a deep understanding of surface reconstruction and a novel perspective for rational design of high performance transition metal phosphide electrocatalysts for water related electrolysis.

Raman spectroscopy is a spectroscopic technique based on Raman scattering effects and provide a structural fingerprint by which molecules can be identified. Owing to its non-destructive, high sensitivity and allowing on-line detection, Raman spectroscopy is now increasingly being applied in various fields from fundamental research to engineering in food safety. Edible oils provide high nutritional value in the human diet and their safety and quality have become a major concern and issue. Thus, edible oils have been the subject of a number of applications of Raman spectroscopy. This present review briefly evaluates Raman spectroscopy applications in the quality and safety analysis of oil products in the latest decade. In addition, by integrating the introduction of the detection of harmful substances and bioactive components in oil product, this paper also summarizes a series of emerging analytical technologies in applications of Raman spectroscopy.

Molybdenum phosphides (MoP) are emerging as an attractive catalyst for water splitting due to their excellent activity and stability. However, most of the MoP synthesized so far are crystalline MoP with relatively fewer exposed active sites and low electrical conductivity. Here, we use a metallo-organic Mo precursor (MoO2(acac)2) to create defect-rich crystalline MoP nanoparticles and uniformly anchor them on reduced graphene oxide (denoted as D-MoP/rGO). High-temperature thermal decomposition of the precursor generates gases, which induce a variety of defects in D-MoP/rGO along with a P-rich surface composition. The electrochemically active surface area of D-MoP/rGO is 8 times that of bulk MoP. D-MoP/rGO requires a small overpotential of 122 mV for the hydrogen evolution reaction (HER) to reach a current density of 10 mA cm−2. Furthermore, density functional theory (DFT) calculation results reveal that surface P sites are the key active sites, which favor the adsorption of H atoms and also act as an H deliverer to promote the HER. Importantly, D-MoP/rGO is also a highly active catalyst for the hydrazine oxidation reaction (HzOR) and requires a low overpotential of 84 mV to reach a current density of 10 mA cm−2. Thus, efficient HER||HzOR hybrid water-splitting can be realized using D-MoP/rGO, which can deliver a current density of 100 mA cm−2 at a small cell voltage of 0.74 V and undergo a stable 12 h operation. In summary, a simple method has been demonstrated to generate high-performance metal phosphide electrocatalysts for total water splitting. Furthermore, the material design concept of creating defective crystalline nanoparticles using gas generating metal precursors can serve as a general approach to create various catalytic active defective crystalline materials.

Designing highly active and robust platinum-free catalysts for hydrogen evolution reaction is of vital importance for clean energy applications yet challenging. Here we report highly active and stable cobalt-substituted ruthenium nanosheets for hydrogen evolution, in which cobalt atoms are isolated in ruthenium lattice as revealed by aberration-corrected high-resolution transmission electron microscopy and X-ray absorption fine structure measurement. Impressively, the cobalt-substituted ruthenium nanosheets only need an extremely low overpotential of 13 mV to achieve a current density of 10 mA cm−2 in 1 M KOH media and an ultralow Tafel slope of 29 mV dec−1, which exhibit top-level catalytic activity among all reported platinum-free electrocatalysts. The theoretical calculations reveal that the energy barrier of water dissociation can greatly reduce after single cobalt atom substitution, leading to its superior hydrogen evolution performance. This study provides a new insight into the development of highly efficient platinum-free hydrogen evolution catalysts., Water splitting provides an appealing route to generating carbon-neutral fuel, however the scarcity and cost of platinum, often used as a catalyst, necessitates a search for alternatives. Here, authors show cobalt atoms in ruthenium nanosheets to afford excellent hydrogen production activities.

Simulation of open quantum dynamics for various Hamiltonians and spectral densities are ubiquitous for studying various quantum systems. On a quantum computer, only log2N qubits are required for the simulation of an N-dimensional quantum system, hence simulation in a quantum computer can greatly reduce the computational complexity compared with classical methods. Recently, a quantum simulation approach was proposed for studying photosynthetic light harvesting [npj Quantum Inf. 4, 52 (2018)]. In this paper, we apply the approach to simulate the open quantum dynamics of various photosynthetic systems. We show that for Drude—Lorentz spectral density, the dimerized geometries with strong couplings within the donor and acceptor clusters respectively exhibit significantly improved efficiency. We also demonstrate that the overall energy transfer can be optimized when the energy gap between the donor and acceptor clusters matches the optimum of the spectral density. The effects of different types of baths, e.g., Ohmic, sub-Ohmic, and super-Ohmic spectral densities are also studied. The present investigations demonstrate that the proposed approach is universal for simulating the exact quantum dynamics of photosynthetic systems.

Curcumae Rhizoma (Ezhu in Chinese) is a multi-origin herbal medicine with excellent clinical efficacy. For fast discrimination and quantification analysis of Ezhu from three botanical origins (Curcuma kwangsiensis, Curcuma phaeocaulis, and Curcuma wenyujin), ultra-violet (UV) spectroscopy and high performance liquid chromatography (HPLC) combined with chemometric tools were employed in this study. Firstly, the analysis method for the simultaneous determination of eleven compounds in Ezhu was developed by HPLC, and the UV spectra of thirty-eight batches of Ezhu were acquired. Then, principal component analysis (PCA), an unsupervised pattern recognition method, was applied on the HPLC and UV spectral data. PCA did not show a clear separation between C. phaeocaulis and C. wenyujin samples with HPLC data. By contrast, the supervised techniques, decision tree (DT) and linear discriminant analysis (LDA), achieved the complete discrimination for the three species of Ezhu with 100 % correct classification rate (CCR), showing excellent performance. Based on UV spectral data, PCA presented good performance for discriminating the three species of Ezhu. LDA, support vector machine (SVM) and k-nearest neighbors (KNN) models provided 96.3 % CCR for the calibration set and 100 % CCR for the validation set. Moreover, the partial least squares (PLS) and back propagation-artificial neural network (BP-ANN) quantitative models established on UV spectral data were satisfactory in predicting the contents of zederone, curdione and 3,5-dihydroxy-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-heptane. The residual predictive deviation (RPD) for zederone, curdione and 3,5-dihydroxy-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-heptane of PLS models were 3.169, 1.502 and 1.735, and that of BP-ANN models were 3.467, 2.481 and 2.370, respectively. The present work proposed a rapid and reliable method for the discrimination of Ezhu from three botanical origins and the prediction of zederone, curdione and 3,5-dihydroxy-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-heptane contents in Ezhu, which will help a lot in the quality control of Ezhu and other multi-origin herbal medicines.

Polyploids play an important role in the breeding of plant for superior characteristics, and many reports have focused on the effects upon photosynthesis from polyploidization in some plant species recently, yet surprisingly little of this is known for barley. In this study, homozygous diploid and tetraploid plants, derived from microspore culturing of the barley cultivar “H30,” were used to assess differences between them in their cellular, photosynthetic, and transcriptomic characteristics. Our results showed that tetraploid barley has the distinct characteristics of polyploids, namely thicker and heavier leaves, enlarged stomata size or stomatal guard cell size, and more photosynthetic pigments and improved photosynthesis (especially under high light intensity). This enhanced photosynthesis of tetraploid barley was confirmed by several photosynthetic parameters, including net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), transpiration rate (Tr), maximum net photosynthetic rate (Pmax), light saturation point (LSP), maximum RuBP saturated rate carboxylation (Vcmax), and maximum rate of electron transport (Jmax). Transcriptomic analyses revealed that just ~2.3% of all detected genes exhibited differential expression patterns [i.e., differentially expressed genes (DEGs)], and that most of these – 580 of 793 DEGs in total – were upregulated in the tetraploid barley. The follow-up KEGG analysis indicated that the most enriched pathway was related to photosynthesis-antenna proteins, while the downregulation of DEGs was related mainly to the light-harvesting cholorophyII a/b-binding protein (Lhcb1) component, both validated by quantitative PCR (qPCR). Taken together, our integrated analysis of morphology, photosynthetic physiology, and transcriptome provides evidences for understanding of how polyploidization enhances the photosynthetic capacity in tetraploids of barley.

The development of oxygen evolution reaction (OER) catalysts with high activity and high stability through convenient and economical methods is greatly important for the promotion of hydrogen energy based on electrolysis technology. Herein, by using an unconventional high electrodeposition potential, novel petal-like clusters constructed by cross-linking ultrathin nickel hydroxide nanosheets were controllably synthesized on nickel foam (or copper foam or carbon cloth) and the effect of electrodeposition conditions on their OER performance was carefully explored. Due to the abundant catalytically active sites, promoting electron conduction/mass transmission from the specific micro-nano structure, as well as the ultrasmall thickness of ∼3.0 nm, the optimized α-Ni(OH)2/NF self-supporting electrode exhibits excellent electrocatalytic performance for OER, merely requiring low overpotentials of 192 and 240 mV to yield current densities of 10 and 100 mA cm-2 in 1.0 M KOH, respectively, which surpassed those of all of the reported nickel hydroxide/oxides and the benchmark RuO2. Moreover, α-Ni(OH)2/NF can drive the high-current density (500-1000 mA cm-2) OER at low overpotentials, meeting the requirements of potential industrial applications.