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The design of assembling high-nuclearity transition-lanthanide (3d-4f) clusters along with excellent magnetocaloric effect (MCE) is one of the most prominent fields but is extremely challenging. Herein, two heterometallic metal coordination polymers are constructed via the “carbonate-template” method, formulated as {[Gd18Ni24(IDA)22(CO3)7(μ3-OH)32(μ2-OH)3(H2O)5Cl]·Cl8·(H2O)14}n and {[Eu18Ni23.5(IDA)22(CO3)7(μ3-OH)32(H2O)5(IN)(CH3COO)2 (NH2CH2COO)Cl]·Cl6·(H2O)17}n [abbreviated as 1-(Gd18Ni24)n and 2-(Eu18Ni23.5)n respectively; H2IDA = iminodiacetic acid; HIN = isonicotinic acid]. Concerning the structures, compounds 1-(Gd18Ni24)n and 2-(Eu18Ni23.5)n both feature the one-dimensional (1D) chain-like structure which is rarely reported in high-nuclearity metal complexes. Meanwhile, the large presences of Gd3+ ions in compound 1-(Gd18Ni24)n are conducive to the fantastic MCE, and the value of −∆Sm is 35.30 J kg−1 K−1 at 3.0 K and ∆H = 7.0 T. And more significantly, compound 1-(Gd18Ni24)n shows the large low-field magnetic entropy change (−∆Sm = 20.95 J kg−1 K−1 at 2.0 K and ∆H = 2.0 T) among the published 3d-4f mixed metal clusters.

The structures, equations of state, phase transitions, mechanical stability, and elastic anisotropies of five SiC polymorphs (wurtzite, 4H, 6H, zinc blende, and rocksalt phases) under pressure were investigated based on first-principles calculations. The optimal structural parameters, densities, and volumes of the five SiC polymorphs under zero and high pressure were obtained and analyzed. The pressures of the phase and stability–instability transitions were predicted using the minimum energy principle and improved Born mechanical stability criteria, respectively, and a new phase transition criterion was developed. The elastic anisotropies of SiC under zero and high pressure were systematically discussed, and the negative Poisson's ratio of zinc blende SiC was verified.

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Background Astaxanthin is a ketocarotenoid with stronger antioxidant activity than vitamin E and coenzyme Q10, and with pharmacological effects against cancer, cardiovascular disease, diabetes, inflammation, and others. Increased astaxanthin supplementation in foods, nutraceuticals, and cosmetic products has resulted in tremendous growth in the demand for natural astaxanthin. Scope and approach Astaxanthin is found widely in aquatic animals and some other organisms, but its de novo synthesis is limited to several bacteria, protists, fungi, algae and plants. Metabolic engineering offers approaches to create systems for high-efficiency production of astaxanthin, which will require in-depth dissection of the astaxanthin synthesis enzymes in the available organisms. Key findings and conclusions Here, we review the de novo synthesis of astaxanthin in bacteria, protists, fungi, algae and plants, and the functional enzymes of specific organisms. A protein-sequence based phylogenetic tree was established to reveal the evolutionary relationships of astaxanthin synthesis proteins across organisms. This review will provide valuable information for the metabolic engineering of astaxanthin bioreactors.

Ultra-small cobalt nanoparticles (NPs) are successfully confined within the mesopores of cubic mesoporous silica KIT-6 via a facile chemical reduction process using double reducing agents sodium borohydride (NaBH4) and ammonia borane (NH3BH3, AB). When the Co NPs embedded KIT-6 catalysts are used as catalysts for generation of hydrogen from hydrolysis of NH3BH3 a superior turnover frequency (TOF) of 20.05 m o l H 2 m o l C o - 1 m i n - 1 and lower activation energy of 32.6 kJ mol−1, better than most of the Co-based catalysts, are achieved. The higher catalytic activity is mainly attributed to the ultra-small size (2.5 nm) of Co NPs and uniform dispersion of Co NPs in the mesopores of KIT-6. Co NPs are also prepared using KIT-6 as the support with another two synthesis routes, namely, single reducing agent NaBH4 and thermal reduction method for comparative study. However, the resulting Co NPs are much larger in size and hence have less catalytic activities. The Co NPs are synthesized within the hexagonal mesopores of SBA-15 as well using double reducing agents in order to study the effect of the pore structure of the support on hydrogen generation. KIT-6 supported Co NPs can produce hydrogen much faster than the SBA-15 supported Co NPs as the 3D interconnected porous structure of KIT-6 allows homogenous transportation and easy diffusion of NH3BH3 molecules to the active sites. The Co NPs in KIT-6 exhibits good recycle ability up to 5 cycles, and the catalyst can be recovered economically from the aqueous solution due to its magnetic nature.

Optical imaging represents one of the most essential tools in biological studies. Although with great advances, bio-optical imaging still suffers from problems such as resolution, sensitivity, speed, and penetration depth. Due to the unique optical properties of gold nanoparticles (AuNPs), i.e., surface plasmon resonance, AuNPs can be readily used to enhance optical imaging based on their absorption, scattering, fluorescence, Raman scattering, etc. Here, we include the most recent achievements and challenges associated with using AuNPs to improve resolution and sensitivity in biological imaging in vitro and in vivo. The application of AuNPs in the following three aspects were discussed: 1) Direct visualization of AuNPs inside the biosystems using i) dark field (DF) microscopy, ii) differential interference contrast (DIC) microscopy, and iii) other techniques, such as interferometric scattering (iSCAT) microscopy and photothermal imaging. Additionally, since orientation and rotational motions are closely related to various biological processes, we also summarized the recent advances of optical imaging methods in the rotational and orientation tracking of AuNPs. 2) Monitoring of biomolecular events and physiological processes using i) surface-enhanced Raman spectroscopy (SERS) and ii) plasmon enhanced fluorescence (PEF) for ultra-sensitive detection of biomolecules, including proteins, metabolites, DNA, RNA, etc. 3) In vivo deep tissue imaging using i) two-photon and/or multi-photon imaging, ii) optical coherence tomography (OCT), and iii) photoacoustic (PA) imaging for disease diagnoses, such as detecting tumors and other diseases in eye, brain, and bone. In conclusion, based on our literature study, AuNPs-assisted bioimaging acts as a promising tool in exploring fundamental biological questions and early diagnosis of diseases.

Cold exposure is one of the most important risk factors for atrial fibrillation (AF), and closely related to the poor prognosis of AF patients. However, the mechanisms underlying cold-related AF are poorly understood.Various techniques including 16S rRNA gene sequencing, fecal microbiota transplantation, and electrophysiological examination were used to determine whether gut microbiota dysbiosis promotes cold-related AF. Metabonomics were performed to investigate changes in fecal trimethylamine (TMA) and plasma trimethylamine N-oxide (TMAO) during cold exposure. The detailed mechanism underlying cold-related AF were examined in vitro. Transgenic mice were constructed to explore the role of pyroptosis in cold-related AF. The human cohort was used to evaluate the correlation between A. muciniphila and cold-related AF.We found that cold exposure caused elevated susceptibility to AF and reduced abundance of Akkermansia muciniphila (A. muciniphila) in rats. Intriguingly, oral supplementation of A. muciniphila ameliorated the pro-AF property induced by cold exposure. Mechanistically, cold exposure disrupted the A. muciniphila, by which elevated the level of trimethylamine N-oxide (TMAO) through modulation of the microbial enzymes involved in trimethylamine (TMA) synthesis. Correspondingly, progressively increased plasma TMAO levels were validated in human subjects during cold weather. Raised TMAO enhanced the infiltration of M1 macrophages in atria and increased the expression of Casp1-p20 and cleaved-GSDMD, ultimately causing atrial structural remodeling. Furthermore, the mice with conditional deletion of caspase1 exhibited resistance to cold-related AF. More importantly, a cross-sectional clinical study revealed that the reduction of A. muciniphila abundance was an independent risk factor for cold-related AF in human subjects.Our findings revealed a novel causal role of aberrant gut microbiota and metabolites in pathogenesis of cold-related AF, which raises the possibility of selectively targeting microbiota and microbial metabolites as a potential therapeutic strategy for cold-related AF.This work was supported by grants from the State Key Program of National Natural Science Foundation of China (No.81830012), and National Natural Science Foundation of China (No.82070336, No.81974024), Youth Program of the National Natural Science Foundation of China (No.81900374, No.81900302), and Excellent Young Medical Talents supporting project in the First Affiliated Hospital of Harbin Medical University (No. HYD2020YQ0001).

Microstructural analysis with electron backscatter diffraction (EBSD) involves sectioning and polishing to create a flat and preparation-artifact free surface. The quality of EBSD analysis is often dependant on this step, and this motivates us to explore how broad ion beam (BIB) milling can be optimised for the preparation of zircaloy-4 with different grain sizes. We systematically explore the role of ion beam angle, ion beam voltage, polishing duration and polishing temperature and how this changes the surface roughness and indexing quality. Our results provide a method to routinely prepare high-quality Zircaloy-4 surfaces, and methods to optimise BIB polishing of other materials for high-quality EBSD studies., as submitted, after 1 round of review

Chitosan/graphene oxide composites (CGs) were developed using directional freezing to create aligned porous three-dimensional (3D) scaffolds resembling bone lamellae. The contact provided by the anisotropic scaffolds played a critical role in guiding the alignment of MC3T3-E1 cells along the longitudinal direction. The higher mechanical strength, shape-memory, cell alignment guiding capabilities, and protein adsorption ability, render these composites potentially useful as scaffold materials in bone tissue engineering.

In this work, we investigated the microstructure and magnetic properties of FeCoNi (Al) high-entropy alloys (HEAs) prepared by high-pressure solidification (HPS). The results show that incoherent nanoprecipitates distributed in uniaxial grain uniformly, which significantly reduces the average magnetic anisotropy of the alloys. The maximum permeability (μm) of alloys increased prominently (i.e. from 47800 to 169000 in FeCoNi alloy and 78000–205000 in FeCoNiAl alloy) and the intrinsic coercivity decreased by 43% in FeCoNiAl alloy after HPS. Nanoprecipitates were related with the double sluggish diffusion effect (DSDE), which is caused by the coupling of high-entropy and high-pressure during solidification process. DSDE not only ensures the retention of short-range ordering (SRO) structures in the liquid metal, but also inhibits the SRO structures’ growth during the solidification process. These SRO structures provide structural conditions to the nanoprecipitates. The molecular dynamics simulation results provide support to the crucial role of DSDE on short-range ordering structures. HPS can effectively reduce the volume fraction of grain boundary precipitates also due to DSDE. Thus, DSDE exhibited the great significance to understand the microstructure of FeCoNi (Al) HEAs by HPS. The perspective also provides a paradigm to enhance the magnetic property of soft magnetic alloys significantly.

Two isolated polyoxovanadogermanates, [Cd(C2H8N2)2]2{[Cd(C2H8N2)]2[Ge8V12O40(OH)8](H2O)}·7H2O (1, V12Ge8) and {[Cd(C2H8N2)2][Cd(C2H8N2)(H2O)]}{[Cd(C2H8N2)2][Cd(C2H8N2)]2Ge8V12O40(OH)8(H2O)}2·4H2O (2, V24Ge16), have been hydro-/solvothermally synthesized and structurally characterized. All the V ions existed in compounds 1 and 2 are demonstrated in the valence of +4 by bond valence calculation (BVC). Notably, it is the first time to investigate the nonlinear optical (NLO) properties of vanadium-based heteropolyacids and obtain strong two photon responses. The results of open aperture Z-scan based on the two compounds manifest that they are the highest value among the reported polyoxovanadates and may be a decent potential NLO materials. At the same time, the electrochemical and electrocatalytic properties of compounds 1 were also measured in detail. More interestingly, the ratio of compounds 1 and 2 in solvent thermal synthesis can be regulated by adjusting the proportion of mixed solvents, which provides a fresh idea and method for the investigation of polyoxometalate chemistry.

Three types of heterojunctions with crystalline ceria/amorphous titania (cC/aT), amorphous ceria/amorphous titania (aC/aT) and crystalline titania/amorphous ceria (cT/aC) structures were prepared to study the effect of structure on their light absorption and carrier separation. The formation mechanism of both crystalline and amorphous phases was studied in this paper. The light absorption and carrier separation efficiency of the heterojunction are markedly enhanced relative to two pure oxides (TiO2 and CeO2). Defects such as oxygen vacancy from the lattice disorder in the aC/aT sample enable the highest absorption of visible light, but also reduce its carrier separation efficiency. The highest separation efficiency of the carrier was observed in the cT/aC sample due to excellent carrier transport from the crystalline phase to the amorphous phase. The experiment confirmed that the the aC/cT sample has more separated charge carriers to react with organic pollutants compare with the cC/aT and aC/aT samples. The work in this paper is useful for rational design and preparation of heterojunctions made by other oxides with high visible light absorption and carrier separation efficiency.

Pure and SiO2-supported CeO2 samples were prepared by Ce(NO3)3 decomposition, precipitation, and sol–gel methods in an attempt to study the role of SiO2 in the synthesis of these materials. During synthesis process, SiO2 support uniformly adsorbed cerium ions in aqueous solution, preventing nucleation and crystal growth of CeO2 during the subsequent water evaporation and calcination steps. Uniform adsorption and inhibition were enhanced by NH4+ and, to a larger extent, C5H7O5COO-. Despite the dispersion of cerium ions on SiO2 reduced the temperature at which CeO2 was formed, crystal size and crystallinity of CeO2 in composites were significantly lower than that of pure CeO2 sample prepared by the same synthesis method and at the same temperature. Composites were quite stable upon increasing the temperature from 400 to 800 °C. Visible light absorption, reduction, and photocatalytic activity characteristics of CeO2 were improved upon dispersion on SiO2. This work can help synthetize supported oxides with high activity and thermal stability.

The enhancement of near IR ECL from Au nanoclusters by the commonly used good's buffer 4-(2-Hydroxyethyl)-1-Piperazineethanesulfonic Acid (HEPES) as coreactants is presented. Lipoic acid (LA) stabilized Au22 nanocluster is used based on its high quantum efficiency of near IR photoluminescence, also in reference to the EDTA enhancement and metal ion responses previously reported. Metal ions are demonstrated to be effective in modulating ECL signal. Specifically, zinc ion is found to drastically enhance the AuNC-HEPES ECL while magnesium and calcium ions lower the ECL intensity. Differentiation of different metal ions or sensing specificity can be better achieved by both intensity and kinetics analysis. The enhancement in ECL by zinc ions is attributed to the direct coordinate interactions with ligand monolayer in the presence of HEPES and confirmed by similar enhancement in the near IR photoluminescence. The ECL profiles are sensitive to pH and display optimal responses at physiological pH which makes HEPES better suited over EDTA for the corresponding applications. The design is translational to other ions and other amine-based good's buffers.

In this paper, we describe a novel, label-free and nicking enzyme-assisted fluorescence signal amplification strategy that demonstrates to be cost efficient, sensitive, and unique for assaying the RNase H activity and inhibition based on G-quadruplex formation using a thioflavin T (ThT) dye. This novel assay method is able to detect RNase H with a detection limit of 0.03 U /mL and further exhibits a good linearity R2 = 0.9923 at a concentration range of 0.03-1 U/mL under optimized conditions. Moreover, the inhibition effect of gentamycin on the RNase H activity is also studied. This strategy provides a potential tool for the biochemical enzyme analysis and inhibitor screening.

Ammonia (NH3) is the most important alkaline gas in the atmosphere and plays a central role in atmospheric pollution and the global N cycle. Water bodies receive increasing nitrogen inputs from effluents and atmospheric deposition due to anthropogenic activities and are regarded as the major natural NH3 and NH4+ sinks. In this work, floating dynamic flux chambers were deployed at four types of freshwater (rivers, large reservoirs, medium-sized reservoirs and ponds) systems and a coastal seawater system to estimate the water-air NH3 emission fluxes. The NH3 emission fluxes of rivers (26.4 μg NH3 m−2 h−1) were significantly higher than those of other types of freshwater systems, and the NH3 flux of offshore water was unexpectedly high (3.9 μg NH3 m−2 h−1). The ammonium content and water temperature were the most important factors driving NH3 emissions from water bodies. The global NH3 emissions from water bodies reached 8.88 TgN a−1, and this value will increase persistently with global warming and water quality deterioration. Water bodies that are relatively eutrophic and directly affected by anthropogenic activities should be considered reservoirs of inputted N instead of permanent sinks.

The influence of high pressure on the microstructural evolution and mechanical properties of Al–Si–Cu–(Ge)–(Mg) alloys was investigated. With the increased solidification pressure, the secondary dendrite arm spacing (SDAS) of Al decreases, and the eutectic Si undergoes a transformation from the coarse acicular morphology to the coral-like morphology. The well-refined microstructure is attributed to the accelerated nucleation rate and the restrained crystal growth rate under high pressure. The morphological transformation of eutectic Si is ascribed to the synergetic effect of the high undercooling and Cu segregation at the outer surfaces of Si. Besides, the study shows that multiple nano-sized particles emerge in the alloys solidified under high pressure due to the high solid solubility of elements and increased nuclei. These nano-sized particles act as dominating strengthening phases leading to enhanced hardness and compressive strength compared with alloys solidified under atmospheric pressure. The as-cast alloy MG solidified under 4 GPa has the highest mechanical properties with a hardness of 135.2 HV and compressive stress of 721 MPa. The strengthening contribution of variable nano-sized particles was discussed. These results indicate that high pressure can be used as an effective method to introduce structural refinement and nano-sized strengthening phases, thus providing a potential way to improve mechanical properties of Al–Si–Cu-based alloys.

This paper presents a global optimization strategy for the vapor compression refrigeration system (VCRS) based on self-adaptive differential evolution (SADE) algorithm to minimize the system energy consumption with the indoor cooling requirements fulfilled. The simplified hybrid VCRS model is established based on the thermodynamics and heat transfer theory, together with the parameter regression method, to predict the system performance and energy consumption under different working conditions. Then considering the interactions between components, the influences of varying indoor loads and outdoor air conditions, a global optimization problem with constraints is formulated. The SADE algorithm is used to solve the global optimization problem, and the optimal variables settings are obtained. Simulation results demonstrate that the proposed global optimization strategy can improve the VCRS energy efficiency in different time periods while satisfying the cooling demands. Averagely 15.57% energy saving on the typical testing day can be achieved. Moreover, significant energy savings can be obtained during the morning and evening periods with partial indoor cooling loads. Furthermore, to show the effectiveness of proposed SADE strategy, the DE and classical PSO algorithms are compared, and the results indicate that the SADE algorithm can significantly reduce the calculation time, and can avoid local minimum. This research brings a feasible methodology, to reduce the energy consumption of air conditioning systems effectively.

Three 3D structures coordination polymers: [Ln(C2O4)(CH3COO)(H2O)]n (Ln = Gd, Eu, Tb) featuring a three-dimensional (3D) structure were synthesized with light-weight ligands. 1Gd owing to the higher magnetic density based on the large mass ratio (metal/ligands) and 3D structures, shows good MCE with −ΔSmmax = 39.5 J kg−1 K−1 at 2 K and ΔH = 7 T. Meanwhile, the luminescence properties and luminescence decay of 2Tb and 3Eu were investigated, the results showed that 2Tb and 3Eu present characteristic emissions of EuIII and TbIII ions.

A free-standing magneto-fluorescent La 1–x Sr x MnO 3 @ZnO multifunctional core-shell nanoparticle system with a sharp, tight phase transition from ferromagnetic to superparamagnetic states, was synthesized by a modified nanoemulsion process with poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO) as the surfactant. The XRD and TEM/HRTEM show high crystallinity of the La 1-x Sr x MnO 3 @ZnO nanoparticles and an average particle size of ∼22.2 nm. The measurements using UV-vis, PL, VSM and PPMS reveal that the nanoparticles exhibit well-behaved absorption bands and multiple visible fingerprint photoluminescent emissions in both aqueous and organic media, and superparamagnetic behavior at room temperature. Particularly, a tight, sharp phase transition from ferromagnetic to superparamagnetic states is observed in the La 1-x Sr x MnO 3 @ZnO nanoparticle system for the first time with a Curie temperature around room temperature. The results demonstrate that the multifunctional La 1-x Sr x MnO 3 @ZnO core-shell nanoparticles could be of interest for scientific studies and potential applications.

Bimetallic CoCu nanoparticles (NPs) are successfully embedded within the cage-type mesopores of COOH functionalized mesoporous silica SBA-16 by double agent chemical reduction method. The presence of the COOH groups in SBA-16 control the size and dispersion of the CoCu NPs. CoCu@S16LC-20 is used as the catalyst for the hydrolysis of ammonia borane (AB) and reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The catalytic activity of the CoCu@S16LC-20 outperforms that of monometallic counterparts Co and Cu. In particular, Co40Cu60@ S16LC-20 can release H2 at a rate of 6570 mL min−1 g−1 and reveals superb catalytic activity with a turn over frequency (TOF) of 16.36 mol H2 min−1 molcatalyst−1. The superior catalytic activity of the bimetallic CoCu@S16LC-20 could be ascribed to the strong synergistic effects emerging from the modified electronic structure, smaller particle size, and 3-dimensional (3D) mesoporous silica support. The smaller particle size renders more active sites, and the mesoporous silica support provides easier paths for transfer of reactants to the catalyst. The catalyst magnetic nature permits straightforward recovery from the aqueous solution after reaction completion which enhances the reusability. The bimetallic Co40Cu60@S16LC-20 can degrade 4-NP to 4-AP at rapid rate of 3.85 × 10−2 s−1 in presence of reducing agent NaBH4.