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The size-dependence of surface plasmon resonances (SPRs) is poorly understood in the small particle limit due to complex physical/chemical effects and uncertainties in experimental samples. In this article, we report an approach for synthesizing an ideal class of colloidal Ag nanoparticles with highly uniform morphologies and narrow size distributions. Optical measurements and theoretical analyses for particle diameters in the d ≈ 2–20 nm range are presented. The SPR absorption band exhibits an exceptional behavior: As size decreases from d ≈ 20 nm it blue-shifts but then turns over near d ≈ 12 nm and strongly red-shifts. A multilayer Mie theory model agrees well with the observations, indicating that lowered electron conductivity in the outermost atomic layer, due to chemical interactions, is the cause of the red-shift. We corroborate this picture by experimentally demonstrating precise chemical control of the SPR peak positions via ligand exchange.

Iron, zinc, and calcium are essential micronutrients that play vital biological roles to maintain human health. Thus, their deficiencies are a public health concern worldwide. Mitigation of these deficiencies involves micronutrient fortification of staple foods, a strategy that can alter the physical and sensory properties of foods. Peptide–mineral complexes have been identified as promising alternatives for mineral-fortified functional foods or mineral supplements. This review outlines some of the methods used in the determination of the mineral chelating activities of food protein-derived peptides and the approaches for the preparation, purification and identification of mineral-binding peptides. The structure–activity relationship of mineral-binding peptides and the potential use of peptide–mineral complexes as functional food ingredients to mitigate micronutrient deficiency are discussed in relation to their chemical interactions, solubility, gastrointestinal digestion, absorption, and bioavailability. Finally, insights on the current challenges and future research directions in this area are provided.

Phase-stability in a U-Zr-Te-Nd multi-component metallic fuel for advanced nuclear reactors is systematically investigated by taking into account binary, ternary and quaternary interactions between elements involved. Historically, the onset of fuel-cladding chemical interactions (FCCI) greatly limits the burnup potential of U-Zr fuels primarily due to interactions between lanthanide fission products and cladding constituents. Tellurium (Te) is evaluated as a potential additive for U-Zr fuels to bind with lanthanide fission products, e.g. neodymium (Nd), negating or mitigating the FCCI effect. Potential fresh fuel alloy compositions with the Te additive, U-Zr-Te, are characterized. Te is found to completely bind with Zr within the U-Zr matrix. Alloys simulating the formation of the lanthanide element Nd within U-Zr-Te are also evaluated, where the Te-Nd binary interaction dominates and NdTe is found to form as a high temperature stable compound. The experimental observations agree well with the trends obtained from density functional theory calculations. According to the calculated enthalpy of mixing, Zr-Te compound formation is favored in the U-Zr-Te alloy whereas NdTe compound formation is favored in the U-Zr-Te-Nd alloy. Further, the calculated charge density distribution and density of states provide sound understanding of the mutual chemical interactions between elements and phase-stability within the multi-component fuel.

The co-culture technique, mimicking natural microbial interactions, has proven to be successful at activating silent biosynthetic gene clusters (BGCs) to produce novel metabolites or enhance the yield of specific metabolites. To effectively decode induction processes, it is critical to have a comprehensive understanding of intermicrobial interactions across both volatile and non-volatile metabolomes. As part of our attempt to uncover structurally unique and biologically active natural products from mangrove endophytic fungi, Phomopsis asparagi DHS-48 was co-cultured with another mangrove fungal strain, Pestalotiopsis sp. HHL-101. The competition interaction of the two strains was investigated using morphology and scanning electron microscopy (SEM), and it was discovered that the mycelia of the DHS-48 and HHL-101 compressed and tangled with each other in the co-culture system, forming an interwoven pattern. To profile volatile-mediated chemical interactions during fungal co-culture, headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) coupled with orthogonal partial least squares-discriminant analysis (OPLS-DA) was adopted. Meanwhile, non-volatile metabolites from both liquid and solid small-scale co-cultures were profiled via HPLC. Two new polyketides, named phaseolorin K (1) and pestaphthalide C (7), together with 11 known compounds (2–6, 8–13), were characterized from solid-state co-cultivation extracts of these two titled strains. Their planar structures were established by analysis of HRMS, MS/MS, and NMR spectroscopic data, while absolute configurations were assigned using ECD calculations. Co-culture feeding experiments demonstrated that DHS-48 exerts antagonistic activity against HHL-101 through altering its hyphal morphology, which mediated enhanced biosynthesis of non-volatile antimicrobial metabolites 5 and 6. Biological assays revealed that compounds 4–6 exhibited potent in vitro cytotoxicity against human cancer cell lines HeLa and HepG2, compared to the positive controls adriamycin and fluorouracil. Compound 2 moderately inhibited the proliferation of ConA-induced T and LPS-induced B murine spleen lymphocytes.

To elucidate the interactions between crude drugs in Kampo medicines (traditional Japanese medicines), it is important to determine the content of the constituents in a cost-effective and simple manner. In this study, we quantified the constituents in crude drug extracts using thin-layer chromatography (TLC), an inexpensive and simple analytical method, to elucidate the chemical interactions between crude drugs. We focused on five crude drugs, for which quantitative high-performance liquid chromatography (HPLC) methods are stipulated in the Japanese Pharmacopoeia XVIII (JP XVIII) and compared the analytical data of HPLC and TLC, confirming that the TLC results corresponded with the HPLC data and satisfied the criteria of JP XVIII. (Z)-ligustilide, a major constituent in Japanese Angelica Root, for which a method of quantification has not been stipulated in JP XVIII, was also quantitatively analyzed using HPLC and TLC. Furthermore, Japanese Angelica Root was combined with 26 crude drugs to observe the variation in the (Z)-ligustilide content from each combination by TLC. The results revealed that combinations with Phellodendron Bark, Citrus Unshiu Peel, Scutellaria Root, Coptis Rhizome, Gardenia Fruit, and Peony Root increased the (Z)-ligustilide content. Quantifying the constituents in crude drug extracts using the inexpensive and simple TLC method can contribute to elucidating interactions between crude drugs in Kampo medicines, as proposed by the herbal-pair theory.

The high costs of mycoinsecticides restrain their extensive application in green agriculture. Two six-week field trials were performed in spring to test synergistic effects of fungal–chemical interactions against faba bean aphid (Aphis fabae) populations in Zhejiang, China. The treatments (three 50-m2 plots each) in each trial included Beauveria bassiana ZJU435 (Bb) and imidacloprid (ImD) applied biweekly at recommended rates (1.5 × 1013 conidia and 45 a.i. g ha−1) and co-applied at reduced rates of 2/3Bb, 1/2Bb, and 1/3Bb plus 1/5ImD, which reduced the cost of the mycoinsecticide by 32–65%. During the first three weeks at 1.3–12.5 °C (daily means), the aphid population steadily increased to a peak in the blank control, and it was much more effectively suppressed by ImD than by Bb and Bb + ImD treatments. As the weather subsequently warmed to 8.7–21.0 °C, the aphid population was increasingly suppressed by the Bb and Bb + ImD treatments, which showed suppressive effects superior or close to those of ImD on days 35 and 42. Percent efficacy values (n = 36) of ImD, 2/3Bb + 1/5ImD, 1/2Bb + 1/5ImD, Bb, and 1/3Bb + 1/5ImD in two six-week trials averaged respectively 86%, 66%, 62.2%, 59.4%, and 58.4%, which significantly differed from one another (p < 0.01). Conclusively, low-rate co-applications of fungal/chemical insecticides offer a ‘low-cost–high-efficacy’ strategy to promote extensive mycoinsecticide application for sustainable aphid control.

Drugs are an important means to treat various diseases. They are classified into several classes to indicate their properties and effects. Those in the same class always share some important features. The Kyoto Encyclopedia of Genes and Genomes (KEGG) DRUG recently reported a new drug classification system that classifies drugs into 14 classes. Correct identification of the class for any possible drug-like compound is helpful to roughly determine its effects for a particular type of disease. Experiments could be conducted to confirm such latent effects, thus accelerating the procedures for discovering novel drugs. In this study, this classification system was investigated. A classification model was proposed to assign one of the classes in the system to any given drug for the first time. Different from traditional fingerprint features, which indicated essential drug properties alone and were very popular in investigating drug-related problems, drugs were represented by novel features derived from a large drug network via a well-known network embedding algorithm called Node2vec. These features abstracted the drug associations generated from their essential properties, and they could overview each drug with all drugs as background. As class sizes were of great differences, synthetic minority over-sampling technique (SMOTE) was employed to tackle the imbalance problem. A balanced dataset was fed into the support vector machine to build the model. The 10-fold cross-validation results suggested the excellent performance of the model. This model was also superior to models using other drug features, including those generated by another network embedding algorithm and fingerprint features. Furthermore, this model provided more balanced performance across all classes than that without SMOTE.

Covalent molecular frameworks are crystalline microporous materials assembled from organic molecules through strong covalent bonds in a process termed reticular synthesis. Diercks and Yaghi review developments in this area, noting the parallels between framework assembly and the covalent assembly of atoms into molecules, as described just over a century ago by Lewis. Emerging challenges include functionalization of existing frameworks and the creation of flexible materials through the design of woven structures. Science , this issue p. eaal1585 Just over a century ago, Lewis published his seminal work on what became known as the covalent bond, which has since occupied a central role in the theory of making organic molecules. With the advent of covalent organic frameworks (COFs), the chemistry of the covalent bond was extended to two- and three-dimensional frameworks. Here, organic molecules are linked by covalent bonds to yield crystalline, porous COFs from light elements (boron, carbon, nitrogen, oxygen, and silicon) that are characterized by high architectural and chemical robustness. This discovery paved the way for carrying out chemistry on frameworks without losing their porosity or crystallinity, and in turn achieving designed properties in materials. The recent union of the covalent and the mechanical bond in the COF provides the opportunity for making woven structures that incorporate flexibility and dynamics into frameworks.

Microorganisms produce and excrete a versatile array of metabolites with different physico-chemical properties and biological activities. However, the ability of microorganisms to release volatile compounds has only attracted research attention in the past decade. Recent research has revealed that microbial volatiles are chemically very diverse and have important roles in distant interactions and communication. Microbial volatiles can diffuse fast in both gas and water phases, and thus can mediate swift chemical interactions. As well as constitutively emitted volatiles, microorganisms can emit induced volatiles that are triggered by biological interactions or environmental cues. In this Review, we highlight recent discoveries concerning microbial volatile compounds and their roles in intra-kingdom microbial interactions and inter-kingdom interactions with plants and insects. Furthermore, we indicate the potential biotechnological applications of microbial volatiles and discuss challenges and perspectives in this emerging research field.Microorganisms produce and excrete an array of metabolites with different physico-chemical properties and biological activities. In this Review, Garbeva and colleagues highlight recent discoveries concerning microbial volatile compounds and their roles in intra-kingdom and inter-kingdom communication, and discuss the potential biotechnological applications of microbial volatiles, as well as challenges and perspectives in this emerging research field.

Organic compounds originating from plant metabolism and reaching the environment may inhibit or stimulate germination and early developmental processes of other plants grown in the vicinity. The aim of this study was to investigate the allelopathic interactions of brown mustard with four other aromatic plants (summer savoury, coriander, caraway and common sage). While health-promoting metabolites of brown mustard are thoroughly investigated and the plant receives an increasing interest from cultivators of aromatic and medicinal plants, its allelopathic interactions with other aromatic plants are poorly documented. The experiments were performed in closed germination vessels, under controlled conditions. The influence of the presence or absence of light, as well as of a sufficient or reduced water supply on the co-germination of brown mustard seeds with each of the other four aromatic plants was also evaluated. The presence of brown mustard reduced the germination velocity of caraway, coriander, sage and savoury. It inhibited stem elongation, but stimulated root growth of savoury. Shoot growth of coriander seedlings was enhanced by the vicinity of brown mustard plantlets. Caraway slowed down the germination of brown mustard seeds, but it stimulated root and stem elongation of the seedlings. The presence of savoury enhanced the fresh biomass production of brown mustard. Common sage inhibited root growth, but stimulated stem elongation of brown mustard plantlets. Most of the allelopathic effects were more pronounced under water shortage than under sufficient water supply. Positive interspecific influences on biomass production were, in most cases, more pronounced in the presence of light. The findings may contribute to optimization of brown mustard cultivation in small parcels, in the vicinity of other aromatic plants, some allelopathic interactions being able to stimulate growth and developmental processes in an environmental-friendly and cost-effective manner.