Latest ArticlesSingle atom catalysts (SACs) have become the frontier research fields in catalysis. The M1-Nx-Cy based SACs, wherein single metal atoms (M1) are stabilized by N-doped carbonaceous materials, have provided new opportunities for catalysis due to their high reactivity, maximized atomic utilization, and high selectivity. In this review, the fabrication methods of M1-Nx-Cy based SACs via support anchoring strategy and coordination design strategy are summarized to help the readers understand the interaction mechanism of single atoms and support. Then, characterization technologies for identifying single metal atoms are presented. Besides, the environmental applications including management of harmful gases, water purification are discussed. Finally, future opportunities and challenges for preparation strategies, mechanisms and applications are concluded. We conclude this review by emphasizing the fact that M1-Nx-Cy based SACs has the potential to become an important candidate for solving current and future environmental pollution problems.
Ferroelectric semiconductors have sparked growing attention in the field of optoelectronics, due to their unique ferroelectric photovoltaic effect. Recently, substantial efforts have been devoted to the development of ferroelectric semiconductors, including inorganic oxides, organic-inorganic hybrids, and metal-free perovskites. Nevertheless, reports of ferroelectric semiconductors with a bandgap of less than 2 eV have been scarce. Here, in combination with the incorporation of triiodide (I3−) and the introduction of chiral cations, we successfully constructed a pair of enantiomeric organic-inorganic hybrid ferroelectric semiconductors, (S-1,2-DAP·I)4·I3·BiI6 and (R-1,2-DAP·I)4·I3·BiI6 (R/S-1,2-DAP = (R/S)-(–)-1,2-diaminopropane), which possess high-temperature multiaxial ferroelectric phase transition with an Aizu notation of 422F2(s) at 405 K, a narrow bandgap of 1.56 eV comparable to that of CH3NH3PbI3 (~1.5 eV), and an impressive piezoelectric response (piezoelectric coefficient, d22 of 35 pC/N) on par with PVDF (polyvinylidene fluoride, 30 pC/N). With intriguing attributes, (S-1,2-DAP·I)4·I3·BiI6 and (R-1,2-DAP·I)4·I3·BiI6 exhibit great potential for application of self-power polarized-light detection and piezoelectric sensors.
The combination of cyclopentadiene, β-diketonate and tripyrazoylborate ligands with dysprosium ion afforded five mononuclear compounds: [(Cp)2Dy(Tp*)] (1Dy), [(Cp)Dy(Tp*)Cl(THF)] (2Dy), [(Cp)Dy(Tp)Cl(THF)] (3Dy), [(DBM)Dy(Tp)Cl(THF)] (4Dy), [{(Tp)Dy(DBM)2(H2O)}·THF] (5Dy) (Cp = cyclopentadiene; Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate; Tp = hydrotris(1-pyrazolyl)borate; DBM = dibenzoylmethanoate). Magnetic study revealed that 1Dy and 3Dy exhibited typical butterfly-type hysteresis. AC susceptibility study combined with ab initio calculations indicated that the magnetic relaxation behaviors of 1Dy–4Dy were governed by the Orbach and Raman processes under applied DC field. Moreover, 3Dy showed two-step magnetic relaxation, which was attributed to the static disordering of the coordinated THF molecule. Magnetic anisotropy analysis indicated that it was the relative strength of the interactions between DyIII and surrounding ligands that determined the orientation of the magnetic easy axis.
Nitrogen-doped carbon catalysts with hierarchical porous structure are promising oxygen evolution reaction (OER) catalysts due to the faster mass transfer and better charge carrying ability. Herein, an exquisite high nitrogen-containing ligand was designed and readily synthesized from the low-cost biomolecule adenine. Accordingly, three new MOFs (TJU-103, TJU-104 and TJU-105) were prepared using the Co(Ⅱ) or Mn(Ⅱ) ions as metal nodes. Through rationally controlling pyrolysis condition, in virtue of the high nitrogen content in well-defined periodic structure of the pristine MOFs, TJU-104–900 among the derived MOFs with hierarchical porous structure, i.e., N-doped graphitic carbon encapsulating homogeneously distributed cobalt nanoparticles, could be conveniently obtained. Thanks to the synergistic effect of the hierarchical structure and well dispersed active components (i.e., C=O, Co‒Nx, graphitic C and N, pyridinic N), it could exhibit an overpotential of 280 mV@10 mA/cm2 on carbon cloth for OER activity. This work provides the inspiration for fabrication of nitrogen-doped carbon/metal electrocatalysts from cost-effective and abundant biomolecules, which is promising for practical OER application.
Plastic and elastic behaviors of organic crystals have profound influence on the processability of pharmaceutical substances. Analogous to metals, the identifications of molecular slip planes in organic crystals are regarded as a strategy for harnessing plasticity. In this work, we experimentally characterized the form Ⅱ anhydrous theophylline (THPa) and its monohydrate (THPm) for their distinct plastic and elastic behaviors. Extensive DFT calculations were performed to model the effects of increasing lattice strains on molecular packing. We discovered that the energy barrier associated with the strain-induced molecular rearrangement would link to the plasticity of THPa, and possibly other simple aromatic compounds. Meanwhile, water molecules in THPm disrupt the stacking architecture from THPm and effectively undermine the general mechanism for plasticity. Hydrate formation would therefore be an alternative strategy to engineer the mechanical property of organic crystalline materials.
Food waste (FW) has been recognized as essential reservoir for resource recovery via anaerobic fermentation, which could also bring the potential risk of antibiotic resistance genes (ARGs) dissemination. Although the structural deficiency of FW could be stimulated by enzymatic pretreatment to enhance fermentation efficiency, the influences of enzymatic pretreatment on ARGs fate and microbial metabolic pathways involved in ARGs dissemination have rarely been reported. This work proved that enzymatic pretreatment could effectively decrease the total abundance of ARGs (reduced by 13.8%-24.5%) during long-term FW fermentation. It was found that enzymatic pretreatment significantly reduced the ARGs belonging to the efflux pump, which might be ascribed to its ability to increase membrane permeability. Furthermore, enzymatic pretreatment was in favor of reducing microbial diversity and various potential ARGs host (e.g., Methanosarcina, Clostridium, Prevotella, Parabacteroides). Also, this pretreatment remarkably up-regulated the genetic expressions involved in ABC transporter (e.g., eryF and mntA) and down-regulated the genetic expressions that participated in DNA replication, two-component systems (e.g., uphA and cckA), and quorum sensing (e.g., rpfF and lsrG), thereby decreasing ARGs transmission. This study would expand the insight of the influences of pretreatment method on ARGs fate during FW fermentation, and offer practical guidance on the sustainable management of FW.
Rapid detection of foodborne pathogens is crucial to prevent the outbreaks of foodborne diseases. In this work, we proposed a novel microfluidic biosensor based on magnetorheological elastomer (MRE) and smartphone. First, micropump and microvalves were constructed by deforming the MRE under magnetic actuation and integrated into the microfluidic biosensor for fluidic control. Then, the micropump was used to deliver immune porous gold@platinum nanocatalysts (Au@PtNCs), bacterial sample, and immunomagnetic nanoparticles (MNPs) into a micromixer, where they were mixed, incubated and magnetically separated to obtain the Au@PtNC-bacteria-MNP complexes. After 3, 3′, 5, 5′-tetramethylbenzidine and hydrogen peroxide were injected and catalyzed by the Au@PtNCs, smartphone was used to measure the color of the catalysate for quantitative analysis of target bacteria. Under optimal conditions, this biosensor could detect Salmonella typhimurium quantitatively and automatically in 1 h with a linear detection range of 8.0 × 101 CFU/mL to 8.0 × 104 CFU/mL and a detection limit of 62 CFU/mL. The microfluidic biosensor was compact in size, simple to use, and efficient for detection, and might be used for in-field screening of foodborne pathogens to prevent food poisoning.
Dentin hypersensitivity (DH) associated with dentinal tubule exposure is one of the most common causes of toothache with a rapid onset and short duration. Medication, filling repair, laser irradiation, crown therapy, and desensitizing toothpaste are standard clinical treatment strategies, but unsatisfactory treatment modalities are marked by long-term administration, poor dentinal tubule closure, microleakage, and the development of secondary caries. To improve the treatment efficiency of DH, numerous organic or inorganic biomaterials have been developed to relieve toothache and reverse the instability of desensitization. Biomaterials are expected to participate in dental remineralization to achieve desensitization. This review discusses various biomaterials for DH therapy based on different desensitization mechanisms, including dentinal tubule closure and dental nerve blockade, and presents a perspective on the underlying future of dentin regeneration medicine for DH therapy.
In this study, a continuous-flow procedure containing four steps has been developed to synthesize Pigment Red 53 and modify its crystal structure. This process avoided the problems of conveying highly insoluble reaction intermediates by removing intermediate operating steps. After optimization, the overall yield of Pigment Red 53:1 reached 97.1% in the total residence time of 80 s by this diazotization-coupling-laking-crystal transition process. From batch to continuous flow, the purity of products increased from 97.1% to 98.2% and the median diameter of pigment particles decreased from 14 µm to 1.9 µm. This process achieved a similar crystal transition effect in 18 s as in batch, producing α, δ and ν crystals of Pigment Red 53:2 as expected. In conclusion, this continuous-flow procedure displays advantages in both synthesis and crystal transition, indicating another potential use for industrial application.
Small molecule activators could equally provide powerful tools as inhibitors do for interrogating cellular signal transduction. However, targeted protein activation is chemically challenging. Developing activators against Src homology region 2 domain-containing phosphatase-1 (SHP-1) to block STAT3 pathway represents a promising strategy for DLBCL therapy. Here we reported a new class of thieno[2,3-b]quinoline-procaine hybrid molecules as SHP-1 allosteric activators. The representative hybrid compound 3b displayed SHP-1 activating effect with EC50 of 5.48 ± 0.28 µmol/L. Further investigations confirmed that 3b allosterically interacted with SHP-1, switched it from close to open conformation, blocked SHP-1/p-STAT3 pathway, induced apoptosis and inhibited ABC-DLBCL cell proliferation in vitro, and delayed tumor growth in the xenograft model of SU-DHL-2. Overall, this work offered a novel paradigm to develop SHP-1 allosteric activators through chemical space evolution of PTPs inhibitors, and firstly validated the therapeutic strategy that directly activating SHP-1 alone could be a potential therapy against ABC-DLBCL via blocking STAT3 pathway.
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