A dramatically changing business landscape characterized by volatility and uncertainty (which in turn are driven by unpredictable alterations of conditions by such factors as geopolitical events, ...climate changes, disasters—natural and human causes, reduction in food, potable water, and critical materials supply along with environmental contamination), has created a situation whereby a rethink of Production and Operations Management (POM) strategies and practices is considered timely and appropriate. Against a backdrop of current POM strengths and weaknesses, and expected POM futures, a response path for POM adoption to deal with such uncertainties and risks is proposed and described in some detail. This involves the treatment of POM as a more interconnected and integrated system than has hitherto been the case. Such an interconnected approach is described as a POM symphony where all key players would be playing from the same script and the POM leader must serve as a coach‐coordinator, that is, the symphony's conductor.
•Summary of known inorganic and hybrid Anderson–Evans polyoxometalates.•Current trends in the synthesis of Anderson–Evans polyoxometalates.•Challenge: incorporation of multifunctional hybrids into ...versatile applications.•Unique advantages of Anderson–Evans clusters compared to other polyoxometalates.
One of the most common polyoxometalates (POMs) is the Anderson–Evans archetype with the general formula Hy(XO6)M6O18n−, where y=0–6, n=2–8, M=addenda atoms (MoVI or WVI) and X=a central heteroatom. The Anderson–Evans archetype is a highly flexible POM cluster that allows modification from several point-of-views; (i) it can incorporate a large number of different heteroatoms differing in size and oxidation state, (ii) it can incorporate inorganic and organic cations and molecules demonstrating different coordination motifs, and (iii) covalent attachment with tris(hydroxymethyl)methane ligands allows it to be combined with specific organic functionalities. The catalog of available heteroatoms, counter cations and organic ligands has witnessed a tremendous expansion during the last years ranging from small inorganic anions that act as building-blocks for larger structures to anions in the nanometer range exhibiting multifunctional properties. This in-depth review discusses synthesis approaches and looks into existing Anderson–Evans structures with a special emphasis on structure-property relationship that tris(hydroxymethyl)methane functionalized structures bring. It also covers the successful use of the Anderson–Evans archetype in various fields of classical applications and describes its superiority to other POM archetypes especially in biological applications.
Defined, branched polymer architectures with low dispersity and architectural purity are of great interest to polymer science but are challenging to synthesize. Besides star and comb, especially the ...pom‐pom topology is of interest as it is the simplest topology with exactly two branching points. Most synthetic approaches to a pom‐pom topology reported a lack of full control and variability over one of the three topological parameters, the backbone or arm molecular weight and arm number. A new, elegant, fast, and scalable synthetic route without the need for post‐polymerization modification (PPM) or purification steps during the synthesis to a pom‐pom and a broad variety of topologies made from styrene and dienes is reported, with potential application to barbwire, bottlebrush, miktoarm star, Janus type polymers, or multi‐graft copolymers. The key is to inset short poly(2‐vinyl‐pyridine) blocks (<2 mol% in the branched product) into the backbone as branching points. Carb anions can react at the C6 carbon of the pyridine ring, grafting the arms onto the backbone. Since the synthetic route to polystyrene pom‐poms has only two steps and is free of PPM or purification, large amounts of up to 300 g of defined pom‐pom structures can be synthesized in one batch.
A new, elegant, fast, and scalable synthetic route without the need for post‐polymerization modification (PPM) or purification steps to a pom‐pom and a broad variety of topologies made from styrene and dienes is reported. The key is to inset poly(2‐vinylpyridine) (P2VP) blocks (< 2 mol% in the branched product) into the backbone as branching points for carb anions.
Molybdenum disulfide (MoS2), attracts great attention in hydrogen evolution reaction (HER) field, however, low catalytic activity sites and poor conductivity still limit its further application. In ...this study, an efficient hydrogen evolution electrode with nano-pom-pom multiphasic MoS2 uniformly grew on porous carbonized wood (NP MoS2/CW) was developed. Interestingly, the nano-pom-pom are stacked from sheets of MoS2. Fully exposed active edges of nano-pom-pom MoS2 and high excellent electrical conductivity of carbonized wood enhance collectively electrocatalytic performance for HER. Specifically, the NP MoS2/CW electrode requires an overpotential of 109.5 mV and 305 mV to achieve the current density of 10 mA cm−2 and 400 mA cm−2, respectively (0.5 M H2SO4). NP MoS2/CW has excellent electrocatalytic performance and stability in acidic and alkaline media due to the perfect combination of NP MoS2 unique nanostructure and the unique properties of CW. Therefore, the present work provides a promising strategy into the rational development and utilization of MoS2 for the development of hydrogen evolution.
•3D low tortuosity, high electronic conductivities and unique anisotropic wood-based matrix was constructed.•Nano-pom-pom multiphasic MoS2 grown on wood-based matrix via template-free process.•The nano-pom-pom MoS2/carbonized wood exhibited outstanding catalytic activity in HER.
The evaporation-induced self-assembly process of amphiphilic molecules (4POSS-DL-POM) in a mixed acetone/n-decane solution is investigated using small-angle X-ray scattering. A series of scattering ...data analysis methods is employed to elucidate the structural evolution of heterocluster 4POSS-DL-POM from a fractal network to compact nanoclusters, followed by the formation of core–shell nanoclusters, and ultimately to hcp superlattice structure.
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Self-assembly of nanoclusters (NCs) is an effective synthetic method for preparing functionalized nanomaterials. However, the assembly process and mechanisms in solutions still remain ambiguous owing to the limited strategies to monitor intermediate assembled states. Herein, the self-assembly process of amphiphilic molecule 4POSS-DL-POM (consisting of four polyhedral oligomeric silsesquioxanes, a dendritic linker, and one polyoxometalate) by evaporation of acetone in a mixed acetone/n-decane solution is monitored by time-resolved synchrotron small-angle X-ray scattering (SAXS). Scattering data assessments, including Kratky analysis, pair distance distribution function, and model fitting, track the self-assembly process of 4POSS-DL-POM from a fractal network to compact NCs, then to core–shell NCs, and finally to superlattice structure. The calculated average aggregation number of a core–shell NC is 11 according to the parameters obtained from core-shell model fitting, in agreement with electron microscopy. The fundamental understanding of the self-assembly dynamics from heterocluster into NCs provides principles to control building block shape and guide target aggregation, which can further promote the design and construction of highly ordered cluster-assembled functional nanomaterials.
The SiW12 of polyoxometalates, as reactive center, is supported in different cavities of MIL-101(Cr) by controlling the different synthesis methods, which enhanced the efficiency of photoexcited ...electron-hole pair separation.The synergistic effect of the porous MIL-101(Cr) and SiW12 greatly improves the nitrogen fixation efficiency of the composites.
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The incorporation of polyoxometalates (POMs) in metal-organic frameworks (MOFs) with host-guest structure have proven to be effective strategy to rational design of heterogeneous catalysis. In this study, the Keggin-type POM@MIL-101(Cr) composite catalysts (PMo12, PW12 and SiW12) are synthesized for nitrogen fixation reaction without sacrificial agents at room temperature in the first time. The SiW12 molecules are encapsulated in smaller cavities of MIL-101(Cr) by solvothermal method and in larger cavities by impregnation method, respectively. Solvothermal synthesized catalyst has a performance of 75.56 μmol·h−1·g-1cat and TOF value of 1.95 h−1, which are about 10 and 88 times than that of Na4SiW12O40. The excellent performance is ascribed to the synergistic effect of SiW12 and MIL-101(Cr). The MIL-101(Cr) adsorbs a large amount of N2 and generates sufficiently photogenerated electrons under sunlight irradiation, and electrons quickly transfer to the SiW12 through hydrogen bonds. Moreover, the agglomeration effect of the homogeneous catalyst SiW12 is weakened due to encapsulation with more exposed active sites. This work provides a feasible route to design and synthesize nanocomposite materials with exceptional performance for photocatalytic nitrogen fixation.
•The yield is directly related with the lignin concentration of growing substrate.•Shortened spawn run period was correlated with the loss of substrate hemicellulose.•Common vetch straw and bean ...straw may be recommended as alternative substrates.
The study was carried out to investigate the potential of several kinds of forestry (oak sawdust (OS), poplar sawdust (PS)) and agricultural byproducts (common vessel straw (CV), wheat straw (WS), safflower wastes (SW) and bean straw (BS)) as growing substrate for Hericium erinaceus cultivation, but also assessing the chemical and lignocellulosic changes occurred in the growing substrates during H. erinaceus cultivation process to understand the needs of the fungus. Moreover, the proximate and lignocellulosic composition of H. erinaceus spent mushroom substrate were presented in the study. Among substrates, CV appeared to promote earliness by presenting shorter cropping periods (29 d), whereas maximum yields (115.8 g/kg and 37.3% BE) and heavier basidiomata (54.1 g) were produced by OS substrates. Spawn running time was correlated positively with carbon to nitrogen ratio (C:N) and lignin content of substrates ( r2 = 0.946), while BEs was positively correlated with lignin content ( r2 = 0.846) and inversely correlated to cellulose/ lignin ratio ( r2=–0.955). The moisture, N, ash, lignocellulosic content of all the substrates were changed greatly during H. erinaceus cultivation, but their rates of change varied at different growing stages. The findings indicate that the shortened spawn run period was correlated with the loss of substrate hemicellulose and high lignin concentration in conjunction to their low cellulose/lignin ratio applies a positive effect on yield and BEs of H.erinaceus.
In this study, a new {Co9} cluster-added polyoxometalate (POM) Cs3K4Na5H6BO(OH)2Co9O(OH)(H2O)3(GeW6O26)(B-α-GeW9O34)2·22H2O (1) was successfully synthesized in the presence of inorganic boron sources ...under hydrothermal conditions. Its structural characterizaiton is realized using single-crystal X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, and powder X-ray diffraction. Compound 1 represents the first Co-added POM bonded by a B atom, and its polyoxoanion is constructed by fusing together with one hexalacunary GeW6O26 and two trilacunary B-α-GeW9O34 fragments in an unprecedented V-shaped {Co9} cluster. Additionally, compound 1 is an efficient catalyst for accelerating the Knoevenagel condensation of various aldehydes with malonitrile.
Three phosphomolybdate hybrid derivatives, (H2bib)2.5{HP2Mo18O62}·2H2O (1), (H2bib){Sr⊂H4P6Mo18O73}·6H2O (2), (H2bib)3{Co(H2O)2}{Sr⊂P6Mo16ⅥMo2Ⅴ O73}·6H2O (3) (bib = 1,4-Bis(imidazolyl)butane) were ...built by bib inducer via in situ hydrothermal reaction and fully characterized. Compounds 1 and 2 are bib modified Dawson and basket-like hybrids with complex topologies, respectively. In structure of 3, {P6Mo18O73} polyanions arranged in ABAB manner are alternately bridged by {Co(H2O)2} unit to yield an extended wavy chain, which was expanded into supramolecular sheets and infinite 3-D meshwork. The irregularly shaped tunnels are produced in the spatial structure of 3. The electrochemical tests show compound 3 presents enhance specific capacitance (797.8 F·g−1at 3 A/g), cycle efficiency (96.5% after the 5000th cycle), electrical conductivity, and catalytic activity than those of compounds 1 and 2 due to its structure advantages. Moreover, 3-GCE exhibits electrochemical responses to AA at potential of 0.3 V with the lower detection line of 0.16 μM, the wider linear range of 4.00 μM–4.72 mM, merit selectivity and reproducibility. The merit capacitive and sensing properties of 3 are attributed to introduction of transition metal Co, which not only provides additional redox active sites, but also bridges the basket clusters to form ordered tunnels that providing the necessary paths for ion or electron transmission.
Three hybrid derivatives based on {P2Mo18}/{P6Mo18} were obtained induced by bib ligand via in situ hydrothermal reaction. Comparing compounds 1 and 2, 3 shows improved specific capacitance, electrochemical conductivity, and sensing performance for the detection of AA due to its structural advantages. Display omitted
•Three hybrids based on {P2Mo18}/{P6Mo18} were obtained induced by bib ligand.•3 is an unique 3-D meshwork based on ABAB arranged {P6Mo18} and {Co(H2O)2} linker.•The irregularly shaped tunnels are produced in the spatial structure of 3.•3 shows excellent pseudocapacitance properties and improved electrical conductivity.•3 has electrocatalytic activity and good electrochemical sensing detection for AA.
