Incorporation Of Precursors Research Articles

Organic macromolecules transport a significant proportion of the calcium precursor for nacre formation

The mechanism of nacre formation in gastropods involves a vesicular system that transports organic and mineral precursors from the mantle epithelium to the mineralization chamber. Between them lies the surface membrane, a thick organic structure that covers the mineralization chamber and the forming nacre. The surface membrane is a dynamic structure that grows by the addition of vesicles on the outer side and recedes by the formation of interlamellar membranes on the inner side. By using a combination of electron microscopy imaging and spectroscopy, we have monitored the journey of the vesicles from the mantle epithelium to the mineralization chamber, focusing on the elemental composition of the organic structures at each stage. Our data reveal that transport occurs in lipid bilayer vesicles through exocytosis from the outer mantle epithelium. After release into the surface membrane, chitin undergoes a process of self-assembly and interaction with proteins, resulting in progressive changes of the internal structure of the surface membrane until the final structure of the interlamellar membranes is acquired. Finally, these detach from the inner side of the surface membrane. Elemental analysis revealed the transport of a considerable amount of calcium bound to proteins, likely forming calcium-protein complexes. Statement of significanceThe formation of nacre tablets occurs through the incorporation of organic and mineral precursors extruded from the mantle epithelium. Although much attention has been paid to the presence of amorphous phases in recent decades, the calcium transport system has not yet been elucidated. We have monitored the packaging of organic and mineral precursors in the form of vesicles from the mantle epithelium to the mineralization chamber. We have shown that the surface membrane represents the zone where chitin and protein polymerization takes place, acquiring the final structure for the formation of interlamellar membranes. Interestingly, these organic structures transport a considerable amount of organic calcium into the mineralization chamber, which support a transport system based on acidic calcium-binding proteins.

Detection of Inverse Stable Isotopic Labeling in Untargeted Metabolomic Data.

Stable isotopic labeling is a powerful tool for determining the biosynthetic origin of metabolites and for discovering natural products that incorporate precursors of interest. When isotopically substituted precursors are not available commercially or synthetically, inverse stable isotopic labeling (InverSIL) is a useful alternative. With InverSIL, an organism is grown on an isotopically substituted medium and then fed precursors of natural isotopic abundance which can be tracked by mass spectrometry, thereby bypassing issues with precursor availability. Currently, there is no automated way to identify precursor incorporation in untargeted metabolomic data using InverSIL without specifying an expected change in the mass-to-charge ratio of metabolites that have incorporated the precursor. This makes it difficult to identify unknown natural products that may incorporate portions of precursors of interest using new biochemistry or to rapidly identify incorporation of multiple precursors into different metabolites simultaneously. To address this, we developed a new, robust workflow for the automated identification of inverse labeling in untargeted metabolomic data. We then use this method to identify metabolites that incorporate para-aminobenzoic acid and different portions of l-methionine, including in the same sample, and in the process discover the likely biosynthetic origin for the C-7 and C-9 methyl groups of the pterin portion of dephosphotetrahydromethanopterin, a C1 transfer coenzyme used by methylotrophic bacteria. This workflow can be applied in the future to streamline the use of the versatile InverSIL approach for natural product and metabolism research.

Nanomolecularly-induced Effects at Titania/Organo-Diphosphonate Interfaces for Stable Hybrid Multilayers with Emergent Properties.

Nanoscale hybrid inorganic-organic multilayers are attractive for accessing emergent phenomena and properties through superposition of nanomolecularly-induced interface effects for diverse applications. Here, we demonstrate the effects of interfacial molecular nanolayers (MNLs) of organo-diphosphonates on the growth and stability of titania nanolayers during the synthesis of titania/MNL multilayers by sequential atomic layer deposition and single-cycle molecular layer deposition. Interfacial organo-diphosphonate MNLs result in ∼20-40% slower growth of amorphous titania nanolayers and inhibit anatase nanocrystal formation from them when compared to amorphous titania grown without MNLs. Both these effects are more pronounced in multilayers with aliphatic backbone-MNLs and likely related to impurity incorporation and incomplete reduction of the titania precursor indicated by our spectroscopic analyses. In contrast, both MNLs result in two-fold higher titania nanolayer roughness, suggesting that roughening is primarily due to MNL bonding chemistry. Such MNL-induced effects on inorganic nanolayer growth rate, roughening, and stability are germane to realizing high-interface-fraction hybrid nanolaminate multilayers.

Mass spectrometry-based metabolomics for the elucidation of alkaloid biosynthesis and function in invasive Vincetoxicum rossicum populations

The genus Vincetoxicum includes a couple of highly invasive vines in North America that threaten biodiversity and challenge land management strategies. Vincetoxicum species are known to produce bioactive phenanthroindolizidine alkaloids that might play a role in the invasiveness of these plants via chemical interactions with other organisms. Untargeted, high-resolution mass spectrometry-based metabolomics approaches were used to explore specialized metabolism in Vincetoxicum plants collected from invaded sites in Ontario, Canada. All metabolites corresponding to alkaloids in lab and field samples of V. rossicum and V. nigrum were identified, which collectively contained 25 different alkaloidal features. The biosynthesis of these alkaloids was investigated by the incorporation of the stable isotope-labelled phenylalanine precursor providing a basis for an updated biosynthetic pathway accounting for the rapid generation of chemical diversity in invasive Vincetoxicum. Aqueous extracts of aerial Vincetoxicum rossicum foliage had phytotoxic activity against seedlings of several species, resulting in identification of tylophorine as a phytotoxin; tylophorine and 14 other alkaloids from Vincetoxicum accumulated in soils associated with full-sun and a high-density of V. rossicum. Using desorption-electrospray ionization mass spectrometry, 15 alkaloids were found to accumulate at wounded sites of V. rossicum leaves, a chemical cocktail that would be encountered by feeding herbivores. Understanding the specialized metabolism of V. rossicum provides insight into the roles and influences of phenanthroindolizidine alkaloids in ecological systems and enables potential, natural product-based approaches for the control of invasive Vincetoxicum and other weedy species.

First insights into the influence of temperature on reproduction in Antarctic fish: The case of Notothenia coriiceps

Understanding the reproductive biology of Antarctic notothenioid fish species is crucial for effective management and conservation efforts. This study investigates the reproductive biology of Notothenia coriiceps, focusing on the location of spawning grounds and the influence of environmental factors on this process. Sampling included 120 specimens caught at Potter Cove, South Shetland Islands, from November to late March of years 2016–2018 (austral spring-summer season). Gonadal macroscopic, histologic and physiologic features are reported. Histological analysis revealed two distinct groups of oocytes in the ovaries: a leading clutch of vitellogenic oocytes for the upcoming reproductive event and a second remnant clutch of smaller oocytes in cortical alveoli and primary growth stages. Photoperiod phases significantly associate with variations in the gonadosomatic index throughout ovarian development, indicating the influence of this parameter on fish reproduction at high latitudes. Elevated plasma levels of estradiol during vitellogenesis support its role in stimulating yolk precursor synthesis and incorporation into oocytes. In March, an increase in testosterone levels during late vitellogenesis suggests the proximity of final maturation, ovulation, and spawning. A sharp increase in both sex steroids and accelerated gonadal development of N. coriiceps was particularly evident after water temperature reached maximum values (∼2 °C), suggesting that high temperature acts as a driver of the physiological mechanisms that allow to complete vitellogenesis and reach the ovulation. Our results show that (1) N. coriiceps females captured in mid-March at Potter Cove were in late developing, suggesting that spawning likely start on April; (2) Potter Cove is likely a spawning ground for N. coriiceps in part due to its thermal regime, emphasizing the importance of inshore areas as spawning grounds for Antarctic notothenioids. Thus, this study underscores the necessity of investigating the impact of water temperature changes on notothenioids reproductive patterns in the context of global warming at West Antarctic Peninsula region.

Linking biosynthetic genes to natural products using inverse stable isotopic labeling (InverSIL).

The sequencing of microbial genomes has far outpaced their functional annotation. Stable isotopic labeling can be used to link biosynthetic genes with their natural products; however, the availability of the required isotopically substituted precursors can limit the accessibility of this approach. Here, we describe a method for using inverse stable isotopic labeling (InverSIL) to link biosynthetic genes with their natural products. With InverSIL, a microbe is grown on an isotopically substituted medium to create a fully substituted culture, and subsequently, the incorporation of precursors of natural isotopic abundance can be tracked by mass spectrometry. This eliminates issues with isotopically substituted precursor availability. We demonstrate the utility of this approach by linking a luxI-type acyl-homoserine lactone synthase gene in a bacterium that grows on methanol with its quorum sensing signal products. In the future, InverSIL can also be used to link biosynthetic gene clusters hypothesized to produce siderophores with their natural products.

Preparation of BiOBr/PVDF photocatalytic membranes for long-term and efficient degradation of organic dyes using phase transition and in situ deposition methods

Purpose This study aims to investigate the morphology and physicochemical properties of BiOBr/Polyvinylidene fluoride (PVDF) composite membranes and the differences in the properties of BiOBr/PVDF composite membranes made by adding different precursor ratios during the casting process. Design/methodology/approach In this paper, sodium bromide and Bi(NO3)3 were used as precursors for the preparation of BiOBr photocatalysts, and PVDF membranes were modified by using the phase conversion method in conjunction with the in situ deposition method to produce BiOBr/PVDF hydrophilic composite membranes with both membrane separation and photocatalytic capabilities. Findings The characterization results confirmed that the composites were successfully and homogeneously co-mingled in the PVDF membranes. The related performance of the composite membrane was tested, and it was found that the composite membrane with the optimal precursor incorporation ratio had good photocatalytic efficiency and antipollution ability; the removal efficiencies of methyl orange, rhodamine B and methylene blue were 80.43%, 85.02% and 86.94%, respectively, in 2.5 h. The photocatalytic efficiency of composite membranes with different precursor ratios increased and then decreased with the increase of the precursor addition ratio. Originality/value The composite membrane is prepared by phase conversion method with in situ deposition method, and the BiOBr material has unique advantages for the degradation of organic dyes. The comprehensive experimental data can be known that the composite membrane prepared in this paper has high degradation efficiency and good durability for organic dyes.

Organo-photoredox-Catalyzed Selective Mono- and Bis-C-H Alkylation of Electron-Rich (Hetero)Arenes.

Herein, we disclose a simple strategy for the C-H alkylation of electron-rich (hetero)arenes with alkyl bromides employing visible-light-mediated organo-photocatalytic SET processes. The generality of this method has been evidenced by the inclusion of a variety of alkyl radicals (α-alkyl-carbonyl, benzyl, cyanomethyl) as well as diverse biologically active electron-rich arenes and (hetero)arenes under mild conditions. The extent of alkylation with alkyl bromides was found to be controlled by introducing Zn(OAc)2 as a bromide scavenger, ensuring the blocking of potential bromo-arene byproduct formation under photoredox conditions. In addition, a sequential C-H alkylation strategy for selective bis-alkylation has also been developed via chronological incorporation of different alkyl radical precursors in one pot quite efficiently.

Tracking Cell Wall-Anchored Proteins in Gram-Positive Bacteria.

Cell wall-anchored surface proteins are integral components of Gram-positive bacterial cell envelope and vital for bacterial survival in different environmental niches. To fulfill their functions, surface protein precursors translocate from cytoplasm to bacterial cell surface in three sequential steps: secretion across the cytoplasmic membrane, covalently anchoring to the cell wall precursor lipid II by sortase A, and incorporation of the lipid II-linked precursors into mature cell wall peptidoglycan. Here, we describe a series of immunofluorescence microscopy methods to track the subcellular localization of cell wall-anchored proteins along the sorting pathway. While the protocols are tailored to Staphylococcus aureus, they can be readily adapted to localize cell wall-anchored proteins as well as membrane proteins in other Gram-positive bacteria.

Incorporation of polysilazane precursor into aluminium melt for in-situ pyrolysis: Synthesis of in-situ metal matrix composites

This manuscript describes a polymer precursor approach to synthesize polymer derived SiCN ceramic dispersed in aluminum metal. The composites were prepared by in-situ pyrolysis of cross-linked polysilazane powder within molten aluminum metal at 800 °C by stir-casting method. The castings were hot extruded, vacuum arc remelted (VAR), and suction cast into copper mold. Microstructure analysis revealed the presence of Si- needles in addition to reinforced particles. The microstructure was dendritic and consisted of a uniform dispersion of SiCN phase within columnar grains, with some segregation to grain boundaries. The VAR process significantly improved the hardness, yield strength and ductility of these composites.

Effect of industrial waste-based precursors on the fresh, hardened and environmental performance of construction and demolition wastes-based geopolymers

The main goal of this study is to evaluate the effects of incorporation of the industrial wastes into Construction and Demolition Waste (CDW)-based geopolymer mixtures. To do this, a series of CDW-based geopolymer paste mixtures were produced and blast furnace slag (BFS), fly ash (FA), and silica fume (SF) were used to partially replace the CDW-based materials at the substitution rate of 10 and 20 % by weight. Flow table, buildability, vane shear, ram extruder and compressive tests were performed to assess some engineering performances of produced mixtures. Besides that, life cycle assessment analysis was conducted to reveal both the environmental impact of CDW-based mixtures and effects of industrial wastes. The results demonstrated that the geopolymer mixture with higher flowability and longer open time can be obtained by the incorporation of industrial waste precursors. Among them, FA incorporation resulted in the highest improvement in flowability while more decrement in shear yield stress was obtained from the SF-incorporated mixtures. Substitution of CDW-based precursors with industrial wastes provided higher compressive strength test results. Although 100% CDW-based geopolymer paste had lower environmental burden, the mixture using FA, BFS and SF followed very closely behind it. The transportation-related impacts were the most determinative factor for the differences between the environmental performance of geopolymer mixtures containing and non-containing industrial waste-based precursors. Overall, the main sources of environmental burdens of CDW-based geopolymer systems were the alkaline activators, electricity, and transportation. Results showed that industrial waste-based precursor can be successfully used in CDW-based geopolymer matrix to adjust engineering properties without endangering the environmental burden of the mixture.

Self-Assembly of Mixed-Dimensional GeS1- x Sex (1D Nanowire)-(2D Plate) Van der Waals Heterostructures.

The integration of dissimilar materials into heterostructures is a mainstay of modern materials science and technology. An alternative strategy of joining components with different electronic structure involves mixed-dimensional heterostructures, that is, architectures consisting of elements with different dimensionality, for example, 1D nanowires and 2D plates. Combining the two approaches can result in hybrid architectures in which both the dimensionality and composition vary between the components, potentially offering even larger contrast between their electronic structures. To date, realizing such heteromaterials mixed-dimensional heterostructures has required sequential multi-step growth processes. Here, it is shown that differences in precursor incorporation rates between vapor-liquid-solid growth of 1D nanowires and direct vapor-solid growth of 2D plates attached to the wires can be harnessed to synthesize heteromaterials mixed-dimensional heterostructures in a single-step growth process. Exposure to mixed GeS and GeSe vapors produces GeS1- x Sex van der Waals nanowires whose S:Se ratio is considerably larger than that of attached layered plates. Cathodoluminescence spectroscopy on single heterostructures confirms that the bandgap contrast between the components is determined by both composition and carrier confinement. These results demonstrate an avenue toward complex heteroarchitectures using single-step synthesis processes.

Engineering single-atom Fe–N active sites on hollow carbon spheres for oxygen reduction reaction

Seeking alternatives to noble metals-based electrocatalysts for oxygen reduction reaction (ORR), hollow carbon spheres (CSs) were finely tuned with stable single-atom Fe–N species through a synthesis methodology requiring only earth-abundant metal precursors. CSs with different sizes were synthesized by sol-gel polycondensation of resorcinol with formaldehyde over silica nanoparticles, followed by thermal annealing and silica etching. A catalyst screening revealed the positive impact of both the hollow core and structural defects of the CSs for ORR. Single-atom Fe–N active sites were introduced on the best performing CSs through simultaneous incorporation of iron and nitrogen precursors, and glucose. A significant enhancement in ORR activity was observed despite the small iron load introduced (0.12 wt%). ORR performance indicators, advanced characterization, and molecular simulation studies revealed nitrogen's crucial role in anchoring individual iron atoms and modulating the charge density nearby the active sites (increase of 80 mV in the half-wave potential). Adding glucose as a chelating agent enhances the metal-heteroatom coordination and subsequent dispersion of iron, accounting for an increase of 20 mV in the half-wave potential, an average of electrons transferred as high as 3.9 (at 0.4 V vs. RHE), and higher stability (99%) than that of a platinum-based (20 wt%) electrocatalyst (92%).

Engineered polymer–clay–copper oxides catalyst for the oxidation and reduction of organic molecules: synergy of degradation and instinctive interface stability by polymer self-healing function

Although many applications of clay–polymer composites have been suggested in recent years, their potential use in water treatment processes has received relatively little attention. This study reports the synthesis, characterization, and application of supramolecular polymer–montmorillonite clay–copper oxide (MPC) as an efficient catalyst for the degradation of rhodamine B (RB), a model organic molecule (OM). MPC was synthesized by incorporating branched polyethyleneimine (PEI) into layered montmorillonite K10 (MK10) through a simple wet impregnation method, followed by the incorporation of a copper precursor and direct reduction of the metal precursor. The resulting MPC was characterized using ATR-FTIR, SEM-EDS, TEM, BJH, XRD, and SAXS. The results confirmed the incorporation of PEI and nano-copper oxides into MK10. The MPC chemically degraded RB (>99% at 5 mg L−1, pH 7) in the aqueous phase (10 mL), and the degradation followed a pseudo-second-order kinetic model with a high correlation coefficient. The synthesized MPC degraded RB (7 h) in the presence of H2O2 and adsorbed RB (>98%) without H2O2. The completeness of RB degradation was validated using liquid–liquid extraction and solid–liquid phase extraction of the aqueous phase and solid MPC after the degradation reaction, respectively. The degradation proceeded through reactive active species (hydroxide radical, •OH), which remained in the solution and are active for 72 h or more. This indicates that the synthesized MPC can degrade trace amounts of RB in larger aqueous volumes. PEI exhibited self-healing behavior (network remodeling) after by mechanical or chemical stress to the PEI/PEI-Cu species during RB degradation, which included the re-formation of RnN–Cu oxides as well as the synergistic effect of charge transfer/recombination between N, Cu, and other reactive species in the reaction mixtures. The post-degradation characterization of MPC confirmed that MPC could be reused for more than five cycles without the loss of copper species. The high catalytic performance of MPC towards the other four organic pollutants in the aqueous phase indicates that MPC is a promising environmental catalyst.

Block Copolymer Enabled Synthesis and Assembly of Chiral Metal Oxide Nanoparticle

Chiral metal oxide nanostructures have received tremendous attention in nanotechnological applications owing to their intriguing chiroptical and magnetic properties. Current synthetic methods mostly rely on the use of amino acids or peptides as chiral inducers. Here, we report a general approach to fabricate chiral metal oxide nanostructures with tunable magneto-chiral effects, using block copolymer (BCP) inverse micelle and R/S-mandelic acid (MA). Diverse chiral metal oxide nanostructures are prepared by the selective incorporation of precursors within micellar cores followed by the oxidation process, exhibiting intense chiroptical properties with a g-factor up to 7.0 × 10-3 in the visible-NIR range for the Cr2O3 nanoparticle multilayer. The BCP inverse micelle is found to inhibit the racemization of MA, allowing MA to act as a chiral dopant that imparts chirality to nanostructures via hierarchical chirality transfer. Notably, for paramagnetic nanostructures, magneto-chiroptical modulation is realized by regulating the direction of the external magnetic field. This BCP-driven approach can be extended to the mass production of chiral nanostructures with tunable architectures and optical activities, which may provide insights into the development of chiroptical functional materials.

Effect of Ag content on the nanostructure and antimicrobial activity of CeO2.

The morphological and antibacterial effects of CeO2 nanoparticles (NPs) with different amounts of Ag precursor were studied. The samples were synthesized with different percentages of silver nitrate content by co-precipitation method. The cerium nitrate hexahydrate was a precursor of Ce reagent, polyvinylpyrrolidone as dispersant agent, and ammonium hydroxide as a precipitating agent. The obtained particles were annealed at 400°C and characterized by X-ray diffraction, scanning electron microscope (SEM), transmission electron microscopy (TEM), and N2 physisorption. The particles show high crystallinity, whose size decreases slightly by the effect of Ag precursor incorporation. These particle morphologies studied by SEM and TEM revealed the spherical shape of CeO2 NPs. Furthermore, the Ag particles were observed with a size of around 30nm. Selected area electron diffraction patterns confirm the cubic structure of CeO2, also the cubic structure of Ag particles. Besides, it was determined that Ag incorporation has no significant influence on the textural properties of NPs. In addition, the antibacterial activity was evaluated against gram-negative and gram-positive microorganisms. The quantitative results showed that the antimicrobial activity increased depending on the Ag amount incorporated, reaching up to 99.999% of the growing reduction rate.

Coupling ultrafine plasmonic Co3O4 with thin-layer carbon over SiO2 nanosphere for dual-functional PMS activation and solar interfacial water evaporation

Photothermal materials afford growing interest in environmental governance, especially for addressing complicated environmental issues including the purification of wastewater and regeneration of freshwater together. Here, we constructed a dual-functional photothermal nanosphere by integrating ultrafine plasmonic Co3O4 (∼10 nm) into an N-doping carbon layer over silica nanosphere (SiO2@Co/C). Biocompatible dopamine coating induces the incorporation of Co precursor and activity optimization of metal species over the SiO2 nanosphere during the synthetic process. In this way, the SiO2 nanosphere maintains the stable configuration of the carbon coating thin layer to accommodate the local interfacial Co3O4 catalytic active substances. Impressively, this catalyst also owns a well-developed interconnecting N-containing network structure, unconventional redox cycle pair of Co(II)/Co(III), and significant metal-carbon interaction. A controlled thermal procedure (500–800 °C) was implemented to tune the optimized activity state of the catalyst. Under these merits, advanced oxidation process (AOPs) through activating persulfate by the obtained materials to degrade organic pollutants was performed in the presence/absence of sunlight, further validating the appreciable photothermal effect to improve the catalytic thermodynamic behavior. The reaction parameters ad anion interference were studied in detail, and SiO2@Co/C-600 can completely degrade bisphenol A (BPA) (30 mg L-1) with a high reaction rate constant of 0.722 min-1 and a low reaction activation energy of Ea (19.4 kJ/mol), and also shows superior mineralization activity for some stubborn pollutants, including oxytetracycline (OTC), 2,4-dichlorophenol and tetracycline (TC) through the reinforced photothermal approach. Besides, SiO2@Co/C-600 shows multiple functions in interfacial solar water evaporation application (1.36 kg m-2 h-1, 81.59 %), revealing great potential value of purification and regeneration of water in the complex pollution condition. This work gives the possibility for the next-generation versatile and competitive photothermal environmental governing materials.

Novel polybenzoxazine and polybenzoxazine/epoxy thermosetting copolymers containing polysilsesquioxane nanostructures for high-performance thermal protection systems

This work focuses on the development of novel thermosetting systems derived from a siloxane-based benzoxazine hybrid precursor [Pr(BA-3aptms)], a conventional benzoxazine (BA-a) and a commercial epoxy resin (DGEBA) based on bisphenol A, as a strategy to prepare benzoxazine/benzoxazine and epoxy/benzoxazine copolymers with different amounts of polysilsesquioxanes in their chemical structure. The effect of the siloxane composition on the morphology was investigated, and their influence on the thermal, dynamo-mechanical and flammability properties was elucidated. The obtained results allowed to conclude that an increase of the BA-a or DGEBA content in the copolymers, considerably affects the morphology of the materials. In this sense, the laminar arrangement changed to a nanocluster arrangement when the contents of Si were below 17% w/w for the epoxy/benzoxazine and below 10% w/w for benzoxazine/benzoxazine systems, respectively. Also, the thickness of the organic sheets in the matrices was increased when increasing the content of BA-a or DGEBA in the materials. In addition, the incorporation of the polysilsesquioxane-based precursor in the crosslinked materials improved the investigated properties, such as: thermal, mechanical and flame resistance, and hydrophobic behavior.

A comprehensive review on geotechnical properties of alkali activated binder treated expansive soil

Geopolymer based soil stabilization is an emerging research field as shown by recent research studies which indicate strong potential of their wide use for sustainable ground treatment. This paper comprehensively reviews the literature on expansive soil stabilization using alkali activated binders, focusing on the stabilization mechanism and geotechnical characteristics of treated soil inclusive of mechanical strength and durability characteristics. The stabilization mechanism is governed by the cation exchange process and the geopolymer/hydration products formation. The reported highest unconfined compressive strength (UCS) and California bearing ratio (CBR) of the geopolymer treated expansive soil cured at room temperature are 15 MPa and 81%, respectively and these values satisfy the strength criteria of most of the standards used for road base materials. The findings of the review revealed that incorporation of precursors in the range of 15–20%, alkaline molarities between 5 and 10 M, along with strong alkalis (NaOH or KOH), Ca rich additives, and discrete fibers could enhance the stabilization performance with respect to strength, swell, and durability. Alkaline activation treatment is expensive compared to the conventional Portland cement based stabilization methods, and yet the cost can be significantly reduced by employing cost effective silicates for alkaline activation. Overall, alkali activated binders (AAB) can be sustainable stabilizers to treat expansive soils for satisfactory geotechnical performance (compaction, strength and durability), however, as recommended in this review, further research should be advanced to realize the utmost viability of this promising approach in successful field application.

Nickel-cobalt phosphide terephthalic acid nano-heterojunction as excellent bifunctional electrocatalyst for overall water splitting

Recent research has focused on preparing excellent and inexpensive bifunctional transition metal electrocatalysts, which is challenging. Herein, a facile synthesis strategy for preparing self-supported nickel-cobalt phosphides using terephthalic acid (H2BDC) as metal-organic framework (MOF) precursor is reported. The incorporation of the MOF precursors modulated the electronic structures and improved the performance of the bimetallic transition metal phosphides with the as-prepared electrocatalyst requiring low overpotentials of 170 mV and 323 mV to reach 50 mAcm−2 for HER and OER, respectively. Moreover, the electrocatalyst is employed in an alkaline water electrolyzer and requires 1.57 V to attain a current density of 10 mAcm−2 with long-term stability, surpassing many reported MOF-derived bimetallic transition metal phosphide (TMPs) electrocatalysts. This work explores the incorporation of a rarely studied MOF precursor into self-supported bimetallic TMPs and opens the prospects of designing efficient MOF-derived electrocatalysts for overall water splitting.