Graphitic carbon nitride has been predicted to be structurally analogous to carbon-only graphite, yet with an inherent bandgap. We have grown, for the first time, macroscopically large crystalline thin films of triazine-based, graphitic carbon nitride (TGCN) using an ionothermal, interfacial reaction starting with the abundant monomer dicyandiamide. The films consist of stacked, two-dimensional (2D) crystals between a few and several hundreds of atomic layers in thickness. Scanning force and transmission electron microscopy show long-range, in-plane order, while optical spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations corroborate a direct bandgap between 1.6 and 2.0 eV. Thus TGCN is of interest for electronic devices, such as field-effect transistors and light-emitting diodes.
The choice of reaction solvent has a major influence on the surface area and pore volume in conjugated microporous polymer (CMP) networks synthesized by Sonogashira−Hagihara palladium-catalyzed cross-coupling chemistry of aromatic dibromo monomers with 1,3,5-triethynylbenzene. Four solvents were evaluated for these reactions: N,N-dimethylformamide (DMF), 1,4-dioxane, tetrahydrofuran (THF), and toluene. Networks synthesized in DMF tend to exhibit the highest surface areas (up to 1260 m2/g), whereas those synthesized in toluene have on average significantly lower surface areas and pore volumes. By judicious choice of reaction solvent, microporous materials can be prepared which combine high surface area with a variety of functional groups of interest in applications such as gas storage, molecular separations, and catalysis.
Abstract Bifidobacterium species and strains are key members of the gut microbiota, appearing soon after birth and persisting into adulthood. Resistant starch is an important dietary substrate for adult-associated bifidobacteria, where its fermentation supports host health. However, little is known about how different starch structures interact with bifidobacteria across various ages and ecological niches. To address this, we carried out detailed growth kinetics screening of Bifidobacterium reference strains and unique isolates from breast-fed infants, testing their metabolic interaction with a variety of starch structures. 1 H NMR metabolomics as well as analysis of CAZyme profiles from genomes were generated for each Bifidobacterium -starch combination. For a subset of resistant starch-utilising isolates, we integrated multi-omics approaches to attain further mechanistic interaction insights. Our results revealed that bifidobacterial starch hydrolysis capabilities are closely associated with their CAZyme profiles and appear to be connected to the niche they occupy. Notably, in one isolate of Bifidobacterium pseudolongum , we identified a novel gene cluster containing three multi-functional amylase enzymes complemented by several starch binding modules which were significantly upregulated in response to resistant starch. This gene cluster was also found in the genomes of bifidobacterial isolates from weaning infants and adults. These findings provide new insights into their participation in the maturation process of the infant gut microbiota. Uncovering mechanisms of metabolic interaction between starch structures and bifidobacteria underscores the importance of this ecological function and potential health implications.
The use of potential biostimulants is of broad interest in plant science for improving yields. The application of a humic derivative called fulvic acid (FA) may improve forage crop production. FA is an uncharacterized mixture of chemicals and, although it has been reported to increase growth parameters in many species including legumes, its mode of action remains unclear. Previous studies of the action of FA have lacked appropriate controls, and few have included field trials. Here we report yield increases due to FA application in three European Medicago sativa cultivars, in studies which include the appropriate nutritional controls which hitherto have not been used. No significant growth stimulation was seen after FA treatment in grass species in this study at the treatment rate tested. Direct application to bacteria increased Rhizobium growth and, in M. sativa trials, root nodulation was stimulated. RNA transcriptional analysis of FA-treated plants revealed up-regulation of many important early nodulation signalling genes after only 3 d. Experiments in plate, glasshouse, and field environments showed yield increases, providing substantial evidence for the use of FA to benefit M. sativa forage production.
catena-Poly[[[bis[diaqua(4,4'-bipyridine)cadmium(II)]-bis[mu-(N"-carboxymethyldiethylenetriamine-N,N,N',N"-tetraacetato)cadmium(II)]]-mu-4,4'-bipyridine] tetradecahydrate], [Cd(4)(C(14)H(19)N(3)O(10))(2)(C(10)H(8)N(2))(3)(H(2)O)(4)].14H(2)O or [Cd(4)(HDTPA)(2)(BPY)(3)(H(2)O)(4)].14H(2)O, where BPY is 4,4'-bipyridine and HDTPA(4-) is N"-carboxymethyldiethylenetriamine-N,N,N',N"-tetraacetate, consists of a one-dimensional coordination polymer formed from a secondary building unit which comprises four Cd centres. The chain structure of the title compound was obtained by the use of a multidentate organic ligand, N,N,N',N",N"-diethylenetriaminepentaacetic acid (H(5)DTPA), which forms multiple chelate rings with the Cd metal centres. An extended network is formed via hydrogen bonds.
Suitability of high-amylose starch branching enzyme II (sbeII) flour for industrial processing of wheat convenience foods (i.e., ready-to-eat chilled sandwich bread) is not known, specifically its impacts on bread quality and starch digestibility over chilled storage. Here we evaluated sbeII wheat quality in an industrial pilot plant using Chorleywood bread processing. Industrially-made sbeII bread showed lower volume upon production, and after chilled storage had lower starch digestibility (∼4% difference of starch digested at 90 min) and more resilient crumb texture compared to a wildtype (WT) control. sbeII breads made in a laboratory scale using an optimised AACC method also showed lower starch digestibility when analysed fresh and after chilled storage. Short-range molecular orderring (an indicator of starch crystallinity measured by 13C solid-state NMR) was lower for both fresh and stored bread, which suggested that the enzyme-resistant structures in sbeII bread were independent of starch retrogradation induced by storage.
Encapsulation of pharmaceuticals inside nanoporous materials is of increasing interest due to their possible applications as new generation therapeutics, theranostic platforms, or smart devices. Mesoporous silicas are leading materials to be used as nanohosts for pharmaceuticals. Further development of new generation of nanoscale therapeutics requires complete understanding of the complex host–guest interactions of organic molecules confined in nanosized chambers at different length scales. In this context, we present results showing control over formation and phase transition of nanosize crystals of model flexible pharmaceutical molecule tolbutamide confined inside 3.2 nm pores of the MCM-41 host. Using low loading levels (up to 30 wt %), we were able to stabilize the drug in highly dynamic amorphous/disordered state or direct the crystallization of the drug into highly metastable nanocrystalline form V of tolbutamide (at loading levels of 40 and 50 wt %), providing first experimental evidence for crystallization of pharmaceuticals inside the pores as narrow as 3.2 nm.
Uniform, hierarchically porous inorganic beads (SiO2, Al2O3, TiO2, and ZrO2) have been produced using emulsion-templated polymer beads as templates. The polymer scaffolds were prepared by oil-in-water-in-oil (O/W/O) sedimentation polymerization (Zhang, H.; Cooper, A. I. Chem. Mater. 2002, 14, 4017). The inorganic beads were prepared by simply immersing the polymer scaffold beads in a range of inorganic precursor solutions, followed by sol−gel condensation in air and subsequent calcination of the polymer phase. The hierarchical structures are composed of mesopores (diameters 2−5 nm), micropores (in the case of silica beads), and large emulsion-templated macropores of around 5−10 μm. All of the pores are highly interconnected. The inorganic beads exhibit high macropore volumes as characterized by mercury intrusion porosimetry. Polymer−silica composite beads with micropores and high macropore volumes were also produced. These large inorganic beads (diameters 1.0−1.5 mm) are easily handled and separated and may be useful in applications such as catalysis and separation, especially for macromolecules or viscous systems where large pores are needed to improve mass transport into the pore structure.
Abstract The introduction of fluorine into the structure of pharmaceuticals has been an effective strategy for tuning their pharmacodynamic properties, with more than 40 new drugs entering the market in the last 15 years. In this context, 19 F NMR spectroscopy can be viewed as a useful method for investigating the host–guest chemistry of pharmaceuticals in nanosized drug‐delivery systems. Although the interest in confined crystallization, nanosized devices, and porous catalysts is gradually increasing, understanding of the complex phase behavior of organic molecules confined within nanochambers or nanoreactors is still lacking. Using 19 F magic‐angle‐spinning NMR spectroscopy, we obtained detailed mechanistic insight into the crystallization of flufenamic acid (FFA) in a confined environment of mesoporous silica materials with different pore diameters (3.2–29 nm), providing direct experimental evidence for the formation of a molecular‐liquid‐like layer besides crystalline confined FFA form I.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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