Latest ArticlesThe development of efficient and cost-effective oxygen evolution reaction (OER) electrocatalysts is crucial for clean energy conversion and storage devices, such as water-splitting, CO2 reduction, and metal-air batteries. Herein, we report an efficient 2-dimensional OER catalyst of ultrathin nickel-iron sulfide nanosheets (NiFeS-NS). Dodecanethiol is employed in the synthesis, which prohibits the growth along the Z-axis, thus a nanosheet is obtained. The NiFeS-NS shows high OER catalytic activity, which only requires a small overpotential of 273 mV to achieve the OER current density of 10 mA/cm2 in alkaline electrolyte, and almost no decay after 150 h of chronopotentiometry test. The high performance is attributed to the 2-dimensional structure, the synergistic effect from the Ni and Fe components which promotes the formation of the high valence Ni species, and the tuning effect from the in-situ generated sulfate doping. This work demonstrates the advantages of the 2-dimensional sulfides in electrocatalysis.
Fluorescence (FL) imaging guided photodynamic therapy (PDT) is becoming highly desirable for personalized therapy and precision medicine. In this study, fluorescent polymer nanoparticles TCPP@PEI/PGA were facilely synthesized through electrostatic interaction-mediated self-assembly of porphyrins tetra(4-carboxyphenyl)porphine (TCPP) and polyethylenimine (PEI), and subsequent surface modification with γ-poly(glutamic acid) (γ-PGA). TCPP served a dual function as the FL imaging probe and the photosensitizer. The as-prepared TCPP@PEI/PGA nanoparticles showed excellent water-solubility and biocompatibility, while having outstanding capabilities of in vivo bioimaging and 1O2 generation. FL bioimaging of mice and effective killing of CT 26 cells as well as CT 26 tumor-bearing mice upon laser irradiation were successfully demonstrated when using TCPP@PEI/PGA as theranostic nanoprobes. This study provides a simple but robust method to design and synthesize porphyrin-based polymer nanoparticles for theranostics.
It is of great importance to directionally construct advanced carbon host to achieve high-performance carbon/sulfur cathodes for lithium sulfur batteries (LSBs). Herein, we report a unique hollow pumpkin-like carbon with notable rich-wrinkle microstructure and intrinsically dual doping with N & P elements via a facile annealing process of Aspergillus niger spore. Furthermore, highly conductive polar absorbents, TiC nanoparticles, are in situ implanted into the above Aspergillus niger spore carbon (ANSC) by carbothermal reaction, accordingly forming high-performance ANSC/TiC composite host for sulfur. Impressively, TiC nanoparticles play dual roles of not only pore formation in ANSC matrix but also enhancement of chemical absorption with polysulfides. With the positive synergistic effect between N & P co-doped ANSC matrix and TiC polar absorbent, the designed ANSC/TiC-S cathodes show unique advantages including larger accommodation space for sulfur, higher surface area, enhanced conductivity and better chemical absorption with soluble polysulfide intermediates. Consequently, the ANSC/TiC-S cathodes are endowed with good rate performance (496 mAh/g at 0.5 C) and enhanced long-term cycling stability (736 mAh/g with a capacity retention of 78.8% at 0.1 C after 100 cycles). Our research opens a new door to controllably design advanced composite cathodes from microorganisms for application in lithium sulfur batteries.
Constructing molecule@support composites is an attractive strategy to realize heterogeneous molecular electrocatalysis. Herein, we synthesized metal-organic framework (MOF)-supported molecular catalysts for hydrogen evolution and oxygen reduction reaction (HER/ORR). Ligand exchange strategy was used to prepare molecule@support hybrids due to the same functional group. A series of hybrids were obtained using Co porphyrin (1) and different MOFs including MIL-88(Fe), MOF-5(NiCo) and UIO-66(Zr). The 1@MOF-5(NiCo) had the best HER and ORR activity compared with 1@MIL-88(Fe) and 1@MOF-5(NiCo). These hybrids also exhibited tunable selectivity for ORR with four-electron process, which can be attributed to the synergistic effect of porphyrin molecules and MOFs. This work provides a possibility for molecular catalysts to improve activity of HER and tune selectivity of ORR.
Liquid biopsy is a highly promising method for non-invasive detection of tumor-associated nucleic acid fragments in body fluids but is challenged by the low abundance of nucleic acids of clinical interest and their sequence homology with the vast background of nucleic acids from healthy cells. Recently, programmable endonucleases such as clustered regularly interspaced short palindromic repeats (CRISPR) associated protein (Cas) and prokaryotic Argonautes have been successfully used to remove background nucleic acids and enrich mutant allele fractions, enabling their detection with deep next generation sequencing (NGS). However, the enrichment level achievable with these assays is limited by futile binding events and off-target cleavage. To overcome these shortcomings, we conceived a new assay (Programmable Enzyme-Assisted Selective Exponential Amplification, PASEA) that combines the cleavage of wild type alleles with concurrent polymerase amplification. While PASEA increases the numbers of both wild type and mutant alleles, the numbers of mutant alleles increase at much greater rates, allowing PASEA to achieve an unprecedented level of selective enrichment of targeted alleles. By combining CRISPR-Cas9 based cleavage with recombinase polymerase amplification, we converted samples with 0.01% somatic mutant allele fractions (MAFs) to products with 70% MAFs in a single step within 20 min, enabling inexpensive, rapid genotyping with such as Sanger sequencers. Furthermore, PASEA's extraordinary efficiency facilitates sensitive real-time detection of somatic mutant alleles at the point of care with custom designed Exo-RPA probes. Real-time PASEA' performance was proved equivalent to clinical amplification refractory mutation system (ARMS)-PCR and NGS when testing over hundred cancer patients' samples. This strategy has the potential to reduce the cost and time of cancer screening and genotyping, and to enable targeted therapies in resource-limited settings.
Dielectric elastomers (DEs) have drawn much attention owing to their application prospects in artificial muscles and soft robotics, it is still a big challenge to prepare DEs with high electromechanical performances. This work reports a highly stretchable poly(thioether)-b-polysiloxane-b-poly(thioether) triblock copolymer based homogenous DEs with high electromechanical properties. The triblock copolymer (PSiPGE) was synthesized through the ring-opening polymerization (ROP) of phenyl glycidyl ether (PGE) and carbonyl sulfide (COS) catalyzed by silicon alkoxides. The dipoles (benzene rings) on the side groups of PSiPGE improved the dipole polarizations and the phase separation structure of this triblock copolymer enhanced the interfacial polarizations between poly(thioether) and polysiloxane, and thus improving the dielectric constant (ε', up to 5.8). In addition, the PSiPGE exhibited low elastic modulus (Y, 0.04 MPa), and thus possessed high electromechanical sensitivity (β, ~145 MPa−1) which is much higher than that of most homogenous DEs. This work provides a new strategy to construct homogenous DEs with excellent electromechanical performances, leading to a greater application aspect in the actuated devices.
The large overpotential for conventional Li-O2 batteries is an enormous challenge, which impedes their practical application. Here, we prepare a defective TiO2 (Ov-TiO2) hollow nanosphere as photo-electrocatalyst for photo-assisted Li-O2 batteries to reduce the overpotential. Under illumination, the oxygen vacancies as a charge separation center contribute to the separation of electrons and holes. The generated electrons could promote reducing O2 to Li2O2 during oxygen reduction reaction (ORR) process, while the generated holes are beneficial to Li2O2 decomposition during oxygen evolution reaction (OER) process. Additionally, the proper concentration of oxygen vacancies will decrease the recombination rate between electrons and holes. The photo-assisted Li-O2 batteries with Ov-TiO2-650 exhibit advanced performances, such as the low overpotential (0.70 V), the fine rate capability, and the considerable reversibility accompanied with the formation/decomposition of Li2O2. We expect that these results could open a new mind to design of highly efficient photo-electrocatalysts for photo-assisted Li-O2 battery.
Enterocytozoon hepatopenaei (EHP) infection has seriously affected prawn culture globally. The symptoms of the infection are not apparent, and traditional detection methods are time consuming and low in accuracy. We developed a new onsite rapid testing device (size 18.8 × 16.7 × 6.6 cm3) for EHP based on magnesium pyrophosphate precipitation and facilitated by loop mediated isothermal amplification (LAMP). The design and fabrication of the device enables efficient light absorbance. The device has a highly sensitive detector, high-precision thermal controller, and humanized touch screen. The temperature control precision of the device is 0.2–0.3 ℃ at 60 ℃, 63 ℃, and 65 ℃. The coefficients of variation values (CVV) of the luminous power in one channel at light on and off were found to be 0.0097 and 0.0014, respectively, within 1 h. The CVV of the background, luminous power, and values of eight PCR tubes filled with pure water were all less than 5%. In the EHP experiment, eight samples (including seven positive and one negative) confirmed the effectiveness of the device, and four positive and four negative samples verified whether cross-contamination exists. Among them, the rise time of the curve was about 15 min. These results assert that the developed device exhibits enhanced stability and uniformity and has excellent performance with high sensitivity, good specificity, and low testing time. Moreover, the optimal and minimum absorbance range was 555–655 nm for monitoring the production of LAMP.
At present, replacing the liquid electrolyte in a lithium metal battery with a solid electrolyte is considered to be one of the most powerful strategies to avoid potential safety hazards. Composite solid electrolytes (CPEs) have excellent ionic conductivity and flexibility owing to the combination of functional inorganic materials and polymer solid electrolytes (SPEs). Nevertheless, the ionic conductivity of CPEs is still lower than those of commercial liquid electrolytes, so the development of high-performance CPEs has important practical significance. Herein, a novel fast lithium-ion conductor material LiTa2PO8 was first filled into poly(ethylene oxide) (PEO)-based SPE, and the optimal ionic conductivity was achieved by filling different concentrations (the ionic conductivity is 4.61 × 10−4 S/cm with a filling content of 15 wt% at 60 ℃). The enhancement in ionic conductivity is due to the improvement of PEO chain movement and the promotion of LiTFSI dissociation by LiTa2PO8. In addition, LiTa2PO8 also takes the key in enhancing the mechanical strength and thermal stability of CPEs. The assembled LiFePO4 solid-state lithium metal battery displays better rate performance (the specific capacities are as high as 157.3, 152, 142.6, 105 and 53.1 mAh/g under 0.1, 0.2, 0.5, 1 and 2 C at 60 ℃, respectively) and higher cycle performance (the capacity retention rate is 86.5% after 200 cycles at 0.5 C and 60 ℃). This research demonstrates the feasibility of LiTa2PO8 as a filler to improve the performance of CPEs, which may provide a fresh platform for developing more advanced solid-state electrolytes.
A series of pyrazolone derivatives bearing a tetrasubstituted chiral center were prepared by virtue of a Lewis acid-catalyzed Friedel-Crafts reaction, in which a chiral copper complex was employed as the catalyst. This reaction can be carried out smoothly under mild condition to afford the pyrazolone derivatives with high yields (up to 85%) and excellent enantioselectivities (up to 99%). In addition, the gram scale synthesis proved the practicality of this reaction.
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