2D Nano-Channeled Molybdenum Compounds for Accelerating Interfacial Polysulfides Catalysis in Li-S Battery.

The shuttle effect, which causes the loss of active sulfur, passivation of lithium anode, and leads to severe capacity attenuation, is currently the main bottleneck for lithium-sulfur batteries. Recent studies have disclosed that molybdenum compounds possess exceptional advantages as a polar substrate to immobilize and catalyze lithium polysulfide such as high conductivity and strong sulfiphilicity. However, these materials show incomplete contact with sulfur/polysulfides, which causes uneven redox conversion of sulfur and results in poor rate performance. Herein, a new type of 2D nano-channeled molybdenum compounds (2D-MoNx) via the 2D organic-polyoxometalate superstructure for accelerating interfacial polysulfide catalysis toward high-performance lithium-sulfur batteries is reported. The 2D-MoNx shows well-interlinked nano-channels, which increase the reactive interface and contact surface with polysulfides. Therefore, the battery equipped with 2D-MoNx displays a high discharge capacity of 912.7 mAh g-1 at 1 C and the highest capacity retention of 523.7 mAh g-1 after 300 cycles. Even at the rate of 2 C, the capacity retention can be maintained at 526.6 mAh g-1 after 300 cycles. This innovative nano-channel and interfacial design of 2D-MoNx provides new nanostructures to optimize the sulfur redox chemistry and eliminate the shuttle effect of polysulfides.

Using liquid smoke to control infestations of the ham mite, Tyrophagus putrescentiae, on dry-cured hams during aging.

Eight treatments of edible coatings and nets including liquid smoke (SP and 24P) and xanthan gum (XG) were used to evaluate their effectiveness at controlling mite growth on dry-cured hams. Mite growth was controlled (P < 0.05) in both coating and netting treatments of 1% SP + 1% XG. Increasing SP concentration from 1% to 2% in the SP only treatments without XG did not control mite growth (P > 0.05) in the coating but controlled mite growth (P < 0.05) when infused in the nets. Both coating and netting treatments with 2% 24P + 1% XG controlled mite growth (P < 0.05), and ham cubes with 1% and 2% 24P in infused nets had mite numbers of 4.6 and 9.4, respectively. SP did not impact the sensory attributes of the ham. Results indicate that liquid smoke can potentially be added in coatings or ham nets to control mites and used in an integrated pest management program for dry-cured hams.

Revealing the Secret of Umami Taste of Peptides Derived from Fermented Broad Bean Paste.

To understand the umami taste of fermented broad bean paste (FBBP) and explore the umami mechanism, eight peptides (PKALSAFK, NKHGSGK, SADETPR, EIKKAALDANEK, DALAHK, LDDGR, and GHENQR) were separated and identified via ultrafiltration, RP-HPLC, and UPLC-QTOF-MS/MS methods. Sensory experiments suggested that eight novel peptides showed umami/umami-enhancing and salt-enhancing functions. Significantly, the threshold of EIKKAALDANEK in aqueous solution exceeded that of most umami peptides reported in the past 5 years. The omission test further confirmed that umami peptides contributed to the umami taste of FBBP. Molecular docking results inferred that all peptides easily bind with Ser, Glu, His, and Asp residues in T1R3 through hydrogen bonds and electrostatic interactions. The aromatic interaction, hydrogen bond, hydrophilicity, and solvent-accessible surface (SAS) were the main interaction forces. This work may contribute to revealing the secret of the umami taste of FBBP and lay the groundwork for the efficient screening of umami peptides.

Emerging 2D Materials for Electrocatalytic Applications: Synthesis, Multifaceted Nanostructures, and Catalytic Center Design.

Currently, the development of advanced 2D nanomaterials has become an interdisciplinary subject with extensive studies due to their extraordinary physicochemical performances. Beyond graphene, the emerging 2D-material-derived electrocatalysts (2D-ECs) have aroused great attention as one of the best candidates for heterogeneous electrocatalysis. The tunable physicochemical compositions and characteristics of 2D-ECs enable rational structural engineering at the molecular/atomic levels to meet the requirements of different catalytic applications. Due to the lack of instructive and comprehensive reviews, here, the most recent advances in the nanostructure and catalytic center design and the corresponding structure-function relationships of emerging 2D-ECs are systematically summarized. First, the synthetic pathways and state-of-the-art strategies in the multifaceted structural engineering and catalytic center design of 2D-ECs to promote their electrocatalytic activities, such as size and thickness, phase and strain engineering, heterojunctions, heteroatom doping, and defect engineering, are emphasized. Then, the representative applications of 2D-ECs in electrocatalytic fields are depicted and summarized in detail. Finally, the current breakthroughs and primary challenges are highlighted and future directions to guide the perspectives for developing 2D-ECs as highly efficient electrocatalytic nanoplatforms are clarified. This review provides a comprehensive understanding to engineer 2D-ECs and may inspire many novel attempts and new catalytic applications across broad fields.

Assembling and Regulating of Transition Metal-Based Heterophase Vanadates as Efficient Oxygen Evolution Catalysts.

Developing efficient, durable, and low-cost earth-abundant elements-based oxygen evolution reaction (OER) catalysts by rapid and scalable strategies is of great importance for future sustainable electrochemical hydrogen production. The earth-abundant high-valency metals, especially vanadium, can modulate the electronic structure of 3d metal oxides and oxyhydroxides and offer the active sites near-optimal adsorption energies for OER intermediates. Here, the authors propose a facile assembling and regulating strategy to controllably synthesize a serial of transition metal (CoFe, NiFe, and NiCo)-based vanadates for efficient OER catalysis. By tuning the reaction concentrations, NiFe-based vanadates with different crystallinities can be facilely regulated, where the catalyst with moderate heterophase (mixed crystalline and amorphous structures) shows the best OER catalytic activity in terms of low overpotential (267 mV at the current density of 10 mA cm-2 ), low Tafel slope (38 mV per decade), and excellent long-term durability in alkaline electrolyte, exceeding its noble metal-based counterparts (RuO2 ) and most current existing OER catalysts. This work not only reports a facile and controllable method to synthesize a series of vanadates-based catalysts with heterophase nanostructures for high-performance OER catalysis, but also may expand the scope of designing cost-effective transition metal-based electrocatalysts for water splitting.

Interfacial Atom-Substitution Engineered Transition-Metal Hydroxide Nanofibers with High-Valence Fe for Efficient Electrochemical Water Oxidation.

Developing low-cost electrocatalysts for efficient and robust oxygen evolution reaction (OER) is the key for scalable water electrolysis, for instance, NiFe-based materials. Decorating NiFe catalysts with other transition metals offers a new path to boost their catalytic activities but often suffers from the low controllability of the electronic structures of the NiFe catalytic centers. Here, we report an interfacial atom-substitution strategy to synthesize an electrocatalytic oxygen-evolving NiFeV nanofiber to boost the activity of NiFe centers. The electronic structure analyses suggest that the NiFeV nanofiber exhibits abundant high-valence Fe via a charge transfer from Fe to V. The NiFeV nanofiber supported on a carbon cloth shows a low overpotential of 181 mV at 10 mA cm-2 , along with long-term stability (>20 h) at 100 mA cm-2 . The reported substitutional growth strategy offers an effective and new pathway for the design of efficient and durable non-noble metal-based OER catalysts.

Synthesis and Electronic Modulation of Nanostructured Layered Double Hydroxides for Efficient Electrochemical Oxygen Evolution.

Water electrolysis is considered to be one of the most promising technologies to produce clean fuels. However, its extensive realization critically depends on the progress in cost-effective and high-powered oxygen evolution reaction (OER) electrocatalysts. As a member of the big family of two-dimensional (2D) materials, nanostructured layered double hydroxides (nLDHs) have made significant processes and continuous breakthroughs for OER electrocatalysis. In this Review, the advancements in designing nLDHs for OER in recent years were discussed with a unique focus on their electronic modulations and in situ analysis on catalytic processes. After a brief discussion on different synthetic methodologies of nLDHs, including "bottom-up" and "top-down" approaches, the general strategies to enhance the catalytic performances of nLDHs reported so far were summarized, including compositional substitution, heteroatom doping, vacancy engineering, and amorphous/crystalline engineering. Furthermore, the in situ OER processes and mechanism analysis on engineering efficient nLDHs electrocatalysts were discussed. Finally, the research trends, perspectives, and challenges on designing nLDHs were also carefully outlined. This progress Review may offer enlightening experimental/theoretical guidance for designing highly catalytic active nLDHs and provide new directions to promote their future prosperity for practical utilization in water splitting.

Fabrication of 3D Porous Polyvinyl Alcohol/Sodium Alginate/Graphene Oxide Spherical Composites for the Adsorption of Methylene Blue.

In this study, three-dimensional (3D) networked porous polyvinyl alcohol/sodium alginate/graphene oxide (PVA/SA/GO) spherical composites were fabricated by the sol-gel method and employed as adsorbents for the adsorption of methylene blue (MB) in aqueous solution. The obtained samples were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermal property analysis, and nitrogen adsorption/desorption isotherms. Moreover, the adsorption properties for MB were investigated by batch experiments. The pseudo-first-order and pseudo-second-order equations were used to fit the adsorption kinetics data, and the Langmuir and Freundlich isothermal models were used to analyze the adsorption isothermals. The results showed that the spherical composites had 3D porous structures, and GO, PVA and SA were fused and linked together by self-assembly, physical intertwining, hydrogen bonding, and Ca2+ and boric acid crosslinking. The maximum adsorption capacity of the 3D porous PVA/SA/GO spherical composites for MB was 759.3 mg/g. The adsorption kinetics had a better agreement with the pseudo-secondorder equation than the pseudo-first-order equation, and the equilibrium data followed the Freundlich model.

De Novo Design of Boron-Based Peptidomimetics as Potent Inhibitors of Human ClpP in the Presence of Human ClpX.

Boronic acids have attracted the attention of synthetic and medicinal chemists due to boron's ability to modulate enzyme function. Recently, we demonstrated that boron-containing amphoteric building blocks facilitate the discovery of bioactive aminoboronic acids. Herein, we have augmented this capability with a de novo library design and a virtual screening platform modified for covalent ligands. This technique has allowed us to rapidly design and identify a series of α-aminoboronic acids as the first inhibitors of human ClpXP, which is responsible for the degradation of misfolded proteins.

3-Cyanoallyl boronates are versatile building blocks in the synthesis of polysubstituted thiophenes.

We report the preparation of hitherto unprecedented 3-cyanoallyl boronates using condensation of the parent α-boryl aldehyde and nitriles. The resulting allyl boronates have been used to generate a wide range of borylated thiophenes, which represent a valuable class of heterocycles in modern drug discovery. Subsequent Suzuki-Miyaura cross-coupling enabled the synthesis of pharmaceutically important 3,5-disubstituted aminothiophenes. Moreover, late stage functionalization gave access to borylated bromothiophene and thieno[2,3-b]pyridines.

Synthesis of magnetic graphene oxide grafted polymaleicamide dendrimer nanohybrids for adsorption of Pb(II) in aqueous solution.

In this paper, using maleic anhydride and ethylenediamine as functional monomers, graphene oxide (GO) loaded magnetic Fe3O4 nanoparticles modified by (3-Aminopropyl) triethoxysilane as support, magnetic graphene oxide grafted polymaleicamide dendrimer (GO/Fe3O4-g-PMAAM) nanohybrids were fabricated by divergent method and magnetic separation technology. The obtained samples were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, elementary analyzer and vibrating sample magnetometer. The effects of PMAAM generations, solution pH, Pb(II) initial concentration, temperature and contact time on the adsorption property of the samples for Pb(II) in aqueous solution were studied. The results demonstrated that nitrogen content and adsorption capacity of the as-synthesized samples with amino terminal groups were all higher than their adjacent generations PMAAM with carboxyl terminal groups. Moreover, with increasing generations of PMAAM grafted on to the GO/Fe3O4, the nitrogen content and the adsorption capacity of the samples with the same terminal groups gradually increased. The maximum adsorption capacity of GO/Fe3O4-g-G3.0 for Pb(II) was 181.4mgg-1 at 298K. The rising of temperature was beneficial for the adsorption. The adsorption kinetics had a better agreement with pseudo-second-order equation, and equilibrium data followed the Langmuir model.

Preparation of polyamidoamine dendrimers functionalized magnetic graphene oxide for the adsorption of Hg(II) in aqueous solution.

In this study, using graphene oxide supported Fe3O4 nanoparticles as carriers, ethylenediamine and methyl acrylate as functional monomer, different generations of polyamidoamine dendrimers functionalized magnetic graphene oxide (MGO-PAMAM), up to generation 4.0, were successfully synthesized via step by step growth chemical grafting approach and magnetic separation technology. In the process of synthesizing dendrimers, the generation of dendrimers was increased with the increasing of reaction cycles. In other words, the dendrimers generation is determined from the number of branch iterations. The obtained MGO-PAMAM were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), elemental analysis, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), nitrogen adsorption/desorption isotherm and Zeta potential analysis. The adsorption properties of the synthesized products for Hg(II) in aqueous solution were investigated by batch experiments. The results showed that the MGO-PAMAM with generation 3.0 of dendrimers (MGO-PAMAM-G3.0) has the maximum adsorption capacity of 113.71mg·g-1. The adsorption process of MGO-PAMAM-G3.0 for Hg(II) was well described by the pseudo-second-order kinetics model and the Langmuir isotherm model. The Hg(II) adsorbed on the surface of MGO-PAMAM-G3.0 was reduced to Hg(I) in the adsorption process. In addition, the MGO-PAMAM possesse good magnetic separation performance.

A Family of Routes to Substituted Phenols, Including Meta-Substituted Phenols.

A new family of routes to substituted phenols has been developed. 2-Bromo-3-methoxycyclohex-2-en-1-ones are readily deprotonated at C-6, and the resulting anions react smoothly with a variety of electrophiles; treatment with DBU in PhMe at room temperature then results in efficient aromatization to benzene derivatives of a regiochemically defined substitution pattern. This sequence affords phenolic azides (ArN3), sulfides (ArSR, ArSAr'), selenides (ArSePh), alcohols [ArCH(OH)R], amino derivatives [ArCH(NHSO2Ar')R), and 1,2-benzenediols. A complementary set of substitution patterns is obtained by DIBAL-H reduction or reaction with a Grignard reagent before aromatization; the latter process gives compounds in which the newly introduced substituent is meta to the phenolic hydroxyl.

Synthesis of substituted resorcinol monomethyl ethers from 2-bromo-3-methoxycyclohex-2-en-1-ones.

2-Bromo-3-methoxycyclohex-2-en-1-ones are readily alkylated at C-6 with reactive halides, and then treatment with DBU (2 equiv) in PhMe at room temperature results in smooth loss of bromide and aromatization to resorcinol monomethyl ethers of defined substitution pattern.

A general route to 1,3'-bipyrroles.

A general method is described for the synthesis of 1,3'-bipyrroles. The route involves constructing a pyrrole ring on the nitrogen of a substituted 1H-pyrrole, so as to generate the 1,3'-bipyrrole. In this approach the nitrogen of the starting pyrrole was alkylated with a special Michael acceptor having an allylic leaving group, and the product was then modified in such a way that the second pyrrole ring could be formed by a Paal-Knorr reaction. Two variants of this sequence were examined, one of which led to formation of a 3-hydroxypyridine instead of the second pyrrole ring; the other variant used phenacyl bromide instead of the special Michael acceptor.