Simple Substitution Research Articles

Assembly of Mitochondrial Genomes Using Nanopore Long-Read Technology in Three Sea Chubs (Teleostei: Kyphosidae).

Complete mitochondrial genomes have become markers of choice to explore phylogenetic relationships at multiple taxonomic levels and they are often assembled using whole genome short-read sequencing. Herein, using three species of sea chubs as an example, we explored the accuracy of mitochondrial chromosomes assembled using Oxford Nanopore Technology (ONT) Kit 14 R10.4.1 long reads at different sequencing depths (high, low and very low or genome skimming) by comparing them to 'gold' standard reference mitochondrial genomes assembled using Illumina NovaSeq short reads. In two species of sea chubs, Girella nigricans and Kyphosus azureus, ONT long-read assembled mitochondrial genomes at high sequencing depths (> 25× whole [nuclear] genome) were identical to their respective short-read assembled mitochondrial genomes. Not a single 'homopolymer insertion', 'homopolymer deletion', 'simple substitution', 'single insertion', 'short insertion', 'single deletion' or 'short deletion' were detected in the long-read assembled mitochondrial genomes after aligning each one of them to their short-read counterparts. In turn, in a third species, Medialuna californiensis, a 25× sequencing depth long-read assembled mitochondrial genome was 14 nucleotides longer than its short-read counterpart. The difference in total length between the latter two assemblies was due to the presence of a short motif 14 bp long that was repeated (twice) in the long read but not in the short-read assembly. Read subsampling at a sequencing depth of 1× resulted in the assembly of partial or complete mitochondrial genomes with numerous errors, including, among others, simple indels, and indels at homopolymer regions. At 3× and 5× subsampling, genomes were identical (perfect) or almost identical (quasiperfect, 99.5% over 16,500 bp) to their respective Illumina assemblies. The newly assembled mitochondrial genomes exhibit identical gene composition and organisation compared with cofamilial species and a phylomitogenomic analysis based on translated protein-coding genes suggested that the family Kyphosidae is not monophyletic. The same analysis detected possible cases of misidentification of mitochondrial genomes deposited in GenBank. This study demonstrates that perfect (complete and fully accurate) or quasiperfect (complete but with a single or a very few errors) mitochondrial genomes can be assembled at high (> 25×) and low (3-5×) but not very low (1×, genome skimming) sequencing depths using ONT long reads and the latest ONT chemistries (Kit 14 and R10.4.1 flowcells with SUP basecalling). The newly assembled and annotated mitochondrial genomes can be used as a reference in environmental DNA studies focusing on bioprospecting and biomonitoring of these and other coastal species experiencing environmental insult. Given the small size of the sequencing device and low cost, we argue that ONT technology has the potential to improve access to high-throughput sequencing technologies in low- and moderate-income countries.

Assessing the Adequacy of Morphological Models using Posterior Predictive Simulations.

Reconstructing the evolutionary history of different groups of organisms provides insight into how life originated and diversified on Earth. Phylogenetic trees are commonly used to estimate this evolutionary history. Within Bayesian phylogenetics a major step in estimating a tree is in choosing an appropriate model of character evolution. While the most common character data used is molecular sequence data, morphological data remains a vital source of information. The use of morphological characters allows for the incorporation fossil taxa, and despite advances in molecular sequencing, continues to play a significant role in neontology. Moreover, it is the main data source that allows us to unite extinct and extant taxa directly under the same generating process. We therefore require suitable models of morphological character evolution, the most common being the Mk Lewis model. While it is frequently used in both palaeobiology and neontology, it is not known whether the simple Mk substitution model, or any extensions to it, provide a sufficiently good description of the process of morphological evolution. In this study we investigate the impact of different morphological models on empirical tetrapod data sets. Specifically, we compare unpartitioned Mk models with those where characters are partitioned by the number of observed states, both with and without allowing for rate variation across sites and accounting for ascertainment bias. We show that the choice of substitution model has an impact on both topology and branch lengths, highlighting the importance of model choice. Through simulations, we validate the use of the model adequacy approach, posterior predictive simulations, for choosing an appropriate model. Additionally, we compare the performance of model adequacy with Bayesian model selection. We demonstrate how model selection approaches based on marginal likelihoods are not appropriate for choosing between models with partition schemes that vary in character state space (i.e., that vary in Q-matrix state size). Using posterior predictive simulations, we found that current variations of the Mk model are often performing adequately in capturing the evolutionary dynamics that generated our data. We do not find any preference for a particular model extension across multiple data sets, indicating that there is no 'one size fits all' when it comes to morphological data and that careful consideration should be given to choosing models of discrete character evolution. By using suitable models of character evolution, we can increase our confidence in our phylogenetic estimates, which should in turn allow us to gain more accurate insights into the evolutionary history of both extinct and extant taxa.

Lag Plot: A Novel Method to Determine Viable Bacterial Cell Number via a Single OD Measurement.

Bactericidal activity is a valuable parameter which is considered and measured for antimicrobial compounds. The available standard protocol to evaluate bactericidal activity is based on the direct colony count. Colony counting requires serial dilution, plating, overnight incubation, and direct counting, which is time-and labor-intensive. In regard to eliminate direct plate count, novel techniques were developed based on the real-time growth monitoring which can come with some limitations and drawbacks. These drawbacks encourage us to develop a novel technique with simple procedure to determine viable bacterial cell count. In this procedure, real-time growth monitoring is not required. In fact, after an incubation time, the number of viable bacteria can be determined with a single OD measurement and through an equation. In this regard, four standard bacterial strains, including Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), and Bacillus subtilis (ATCC 23857), were cultured with descending inoculum densities (1.5 × 107 to 15CFU/mL) and growth curves were drawn. As expected, growth in the samples with lower inoculum densities recorded with longer lag phase. Also, a direct relation was observed between the recorded turbidities and initial cell counts. A logarithmic curve (lag plot) was obtained by plotting the OD, after 12-18h incubation, against initial cell counts. In all examined strains, R2 was calculated in the range of 0.96-0.99 which is acceptable value for coefficient of determination. Equation corresponding to the lag plot was obtained and called lag equation. This equation is applicable to calculate the number of viable cells in unknown samples simply by inoculation, incubation, and single OD measurement. Developed technique can be introduced as a simple substitution for labor- and time-intensive direct colony counting.

Platinum(II) acetimino cyclometalated complexes derived from room temperature ammonia activation

Two Pt(II) rollover cyclometalated complexes, [Pt(bpyPh‐H)(DMSO)Me] (1) and [Pt(bpyPh‐H)(DMSO)Cl] (2), where bpyPh‐H is the C3‐deprotonated 6‐phenyl‐2,2’‐bipyridine, were reacted with aqueous ammonia in acetone at room temperature. In the case of the electron‐poor complex 2 simple substitution of DMSO gave the amino complex [Pt(bpyPh‐H)(NH3)Cl] (4), whereas the electron‐rich complex 1 produced the rare acetimine complex [Pt(bpyPh‐H)(HN=CMe2)Me] (3), stable both in solution and in the solid state. The result is noteworthy, as the condensation product of acetone and ammonia, acetimine, is not stable under mild conditions. The reaction likely requires a Pt(II) electron‐rich complex and the presence of a carbon donor in trans position. An analogous reaction occurs with methylamine, allowing the synthesis of the secondary imine complex [Pt(bpyPh‐H)(MeN=CMe2)Me], 5. Starting from this finding a series of cyclometalated acetimine complexes [Pt(N^C)(HN=CMe2)Me] were isolated and characterized with other classical and rollover cyclometalated ligands with an array of different electronic and steric properties, indicating a possible extension of the reaction to various cyclometalated ligands. A preliminary study on the antimicrobial and antitumor properties of complex 3, taken as a model for this class, showed no significant effects against Gram‐positive, Gram‐negative bacteria, or yeasts, but found activity in vitro against HT29 colon cancer cell line.

Synthesis and luminescence properties of carbon quantum dots with core@shell structures

The luminescence stability of carbon quantum dots (CQDs) in air impedes their extensive applications. Ample –NH2 groups on the surface of a green carbon quantum dots (GCQDs) had high organic reactivity, the surface of GCQDs was modified with allyl functional groups through a simple surface substitution reaction (named as GCQD-A). The surface of the GCQD-A was continuously formed a thin organic shell by free radical copolymerization reaction with methyl methacrylate and styrene respectively, and they were named as GCQD@PMMA and GCQD@PS respectively. The allyl functional groups on the surface of GCQD-A, the shell composition of GCQD@PMMA and GCQD@PS were characterized by their 1H nuclear magnetic resonance (1H NMR) data and infrared adsorption spectra. The luminescence stabilities for GCQD@PMMA and GCQD@PS in air were greatly improved compared with that for the GCQDs. The work can provide a novel method to get stable luminescence of CQDs in air, and it will extend their application areas in solid state.

Single-file dynamics with general charge measures.

We study charge fluctuations in single-file dynamics with general charge measures. The exact finite-time distribution of charge fluctuations is obtained in terms of a dressing transformation acting on the finite-time distribution of particle fluctuations. The transformation is mapped to a simple substitution rule for corresponding full-counting statistics. By taking the asymptotics of the dressing transformation, we analyze typical and large scale charge fluctuations. Typical charge fluctuations in equilibrium states with vanishing mean charge are anomalous, while large charge fluctuations undergo first and second order dynamical phase transitions out of equilibrium.

Anodized commercial galvanized grids decorated with Ag nanospheres and Cu worm-like nanorods for photoelectrochemical water splitting

The current work introduces novel and low-cost AgNSs-A@CGGs and CuNRs-A@CGGs photoanodes for the photoelectrochemical (PEC) water-splitting reaction. The photoanodes were fabricated by anodizing commercial galvanized grids(A@CGGs) in the sodium carbonate solution followed by deposition of Ag or Cu through a simple electroless substitution. Surface studies showed that AgNSs-A@CGGs and CuNRs-A@CGGs photoanodes have a unique morphology including Ag nanospheres (AgNSs) and Cu worm-like nanorods (CuNRs) with huge surface area. The UV-VIS diffuse reflectance spectra (DRS) of AgNSs-A@CGGs and CuNRs-A@CGGs photoanodes displayed the lower band gap energies of 2.4 eV, and 2.83 eV respectively, which compared to 3.91 eV for the A@CGGs, showing excellent photoanodic behavior for AgNSs-A@CGGs and CuNRs-A@CGGs photoanodes. Investigations of photoelectrochemical water-splitting under visible light irradiation showed that the production amount of H2 from AgNSs-A@CGGs and CuNRs-A@CGGs photoanodes was about 18570 and 6895 μmol h−1 cm−2 respectively. Moreover, AgNSs-A@CGGs showed 15.27 and 5.0 times higher photoconversion efficiency than CGGs and A@CGGs respectively. In this study, the introduced photoanode grids are expected to be used as cheap and industrial photoanodes for PEC water-splitting and hydrogen gas production.

A study on N-policy BMAP/G/1 queueing system

This study presents a simple approach for analyzing the BMAP/G/1 queueing system under N policy. In this policy, the server goes idle at the end of a busy period and the queue length is checked at every arrival moment. The idle server starts serving customers when the queue length reaches or above a predetermined number, namely N, and keeps doing so until the system is completely empty. We first use a simple sequential substitution approach to derive the system length distribution at departure epoch. A comparative study is also conducted to highlight the benefits and strength of our straightforward approach to that of the RG-factorization technique and the roots finding method. We extract the distribution of system length at a random time point by utilizing the remaining service time of a customer who is currently being served as the supplementary variable. The probability density function of the sojourn time distribution for an arbitrary customer of an incoming batch is also computed. We propose an expected linear cost function to estimate the optimal value of N at minimum cost. The validity of our analytic technique has been shown through a variety of numerical examples involving different service time distributions.

Generalized gluon distribution for quarkonium dynamics in strongly coupled N=4 Yang-Mills theory

We study the generalized gluon distribution that governs the dynamics of quarkonium inside a non-Abelian thermal plasma characterizing its dissociation and recombination rates. This gluon distribution can be written in terms of a correlation function of two chromoelectric fields connected by an adjoint Wilson line. We formulate and calculate this object in N=4 supersymmetric Yang-Mills theory at strong coupling using the AdS/CFT correspondence, allowing for a nonzero center-of-mass velocity v of the heavy quark pair relative to the medium. The effect of a moving medium on the dynamics of the heavy quark pair is described by the simple substitution T→γT in agreement with previous calculations of other observables at strong coupling, where T is the temperature of the plasma in its rest frame, and γ=(1−v2)−1/2 is the Lorentz boost factor. Such a velocity dependence can be important when the quarkonium momentum is larger than its mass. Contrary to general expectations for open quantum systems weakly coupled with large thermal environments, the contributions to the transition rates that are usually thought of as the leading ones in Markovian descriptions vanish in this strongly coupled plasma. This calls for new theoretical developments to assess the effects of strongly coupled non-Abelian plasmas on in-medium quarkonium dynamics. Finally, we compare our results with those from weakly coupled QCD, and find that the QCD result moves toward the N=4 strongly coupled result as the coupling constant is increased within the regime of applicability of perturbation theory. This behavior makes it even more pressing to develop a non-Markovian description of quarkonium in-medium dynamics. Published by the American Physical Society 2024

Development of novel, green, efficient approach for the synthesis of indazole and its derivatives; insights into their pharmacological and molecular docking studies

Indazole is a potent heterocycle with wide range of biological applications. It is less naturally available alkaloid widely used in traditional medicine for the treatment of allergies, blood pressure, etc. In recent years due to the utility of indazoles as pharmacophores in drug discovery, it has been exemplified in recent research. The existing method of synthesis involves carbon-nitrogen bond formation using ccopper, costly Pd metal catalyst i.e.; Buchwald Hartwig coupling. Since it is the need of hour for simple method, we, report a new efficient and economically feasible, user friendly synthesis of indazoles by utilizing less hazardous raw materials, eliminating use of metal catalyst therefore coming up with a greener method. The sequence involves carbon-nitrogen bond formation via simple ipso substitution, by replacing copper and costly Pd, catalyst. This new green synthetic procedure includes two steps synthesis of 1H-indazole derivatives involving arylhydrazones as an intermediate. Further in order to better understand the biological significance of the novel Indazole and its derivatives, Molecular docking studies for antifungal activity were carried out against lanosterol 14 alpha-demethylase for all the newly synthesized molecules with reference to the standard drug fluconazole, in line with above docking studies the in-vitro anti-microbial, anti-oxidant and anti-inflammatory activity were conducted among which our synthesized moieties showed excellent results for antifungal activity. Thus, we report an efficient, eco-friendly strong synthetic method for the synthesis of novel Indazole and its derivatives.

Affordances of Using Educational Technology in Teaching Critical Reading: Insights from an Action Research Study in a Ugandan University

The rapid increase in student enrolment and/or massification, also implicated in large class sizes, has been problematised for compromising quality education. Institutions of higher learning in Africa have embraced the use of ICT as one of the approaches to cope with the challenges of massification. The purpose of this study was to provide an examplar on how teachers can use ICTs to optimise learning from higher-order to lower-order thinking skills. The study uses action research methodology, undertaken with undergraduate students in a Ugandan university, to illuminate the researchers’ experiences in using educational technologies to support the teaching of critical reading. Firstly, we demonstrate how learning progressed from lower-order to higher-order thinking skills as informed by Bloom’s taxonomy. We also show how we optimised the use of technology from the dominant simple substitution, which was also teacher-centred, to a more complex redefinition, which is also learner-centred, as informed by the SAMR model. Finally, we highlight the affordances of using emerging technologies to support transformative learning. These include ongoing learning, monitoring/feedback, research, deeper interaction, peer-review, creativity, and reflection. The study has implications for in-service as well as pre-service teacher education programs which should integrate relevant theoretical frameworks in equipping teachers to optimise the use of technology in supporting teaching and learning.

Steric Control of Luminescence in Phenyl-Substituted Trityl Radicals.

Triphenylmethyl (trityl) radicals have shown potential for use in organic optoelectronic applications, but the design of practical trityl structures has been limited to donor/radical charge-transfer systems due to the poor luminescence of alternant symmetry hydrocarbons. Here, we circumvent the symmetry-forbidden transition of alternant hydrocarbons via excited-state symmetry breaking in a series of phenyl-substituted tris(2,4,6-trichlorophenyl)methyl (TTM) radicals. We show that 3-fold phenyl substitution enhances the emission of the TTM radical and that steric control modulates the optical properties in these systems. Simple ortho-methylphenyl substitution boosts the photoluminescence quantum efficiency from 1% (for TTM) to 65% at a peak wavelength of 612 nm (for 2-T3TTM) in solution. In the crystalline solid state, the neat 2-T3TTM radical shows a remarkably high photoluminescence quantum efficiency of 25% for emission peaking at 706 nm. This has implications in the design of aryl-substituted radical structures where the electronic coupling of the substituents influences variables such as emission, charge transfer, and spin interaction.

Phosphononitrile based bismaleimide electronic packaging substrate with both fire safety and dielectric properties: Assisting 5G communication

Due to the high polarizability of traditional flame retardants, it is difficult to meet the excellent dielectric properties and flame retardancy required for electronic packaging materials. Therefore, we have designed a novel linear polyphosphazene that can balance the dielectric properties and flame retardancy of bismaleimide (BMI) composites. Here, fluorinated aromatic ring structure with the large freedom volume is connected to the main chain of polydichlorophosphazene (PDCP) as a side group, resulting in multifunctional fluorinated linear polyphosphazene (PBTFP). Attributed to the excellent P/N/F combination flame retardant strategy, extremely low polarizability, and large molecular free volume, PBTFP simultaneously improves the dielectric properties and flame retardancy of the BMI composites, including UL-94 rating of V0, and a dielectric constant (Dk) as low as 2.69. In addition, as an elastomer, PBTFP exhibits positive effects on improving the hydrophobicity and toughness of BMI. Therefore, through a simple affinity substitution reaction, we prepared a multifunctional fluorinated linear polyphosphazene modified BMI based electronic packaging substrate material that can be applied to 5G high-frequency communication.

Expanding Chemical Frontiers: Approaches for Generating Diverse and Bioactive Natural Product-Like Compounds Libraries from Extracts.

The realms of natural products and synthetic compounds exhibit distinct chemical spaces that not only differ but also complement each other. While the convergence of these two domains has been explored through semisynthesis and conventional pharmacomodulation endeavours applied to natural frameworks, a recent and innovative approach has emerged that involves the combinatorial generation of libraries of 'natural product-like compounds' (NPLCs) through the direct synthetic derivatization of natural extracts. This has led to the production of numerous NPLCs that incorporate structural elements from both their natural (multiple saturated rings, oxygen content, chiral centres) and synthetic (aromatic rings, nitrogen and halogen content, drug-like properties) precursors. Through careful selection of extracts and reagents, specific bioactivities have been achieved, and this strategy has been deployed in various ways, showing great promise without reaching its full potential to date. This review seeks to provide an overview of reported examples involving the chemical engineering of extracts, showcasing a spectrum of natural product alterations spanning from simple substitutions to complete scaffold remodelling. It also includes an analysis of the accomplishments, perspectives and technical challenges within this field.

Isotope Effect-Enabled Crystal Enlargement in Metal-Organic Frameworks.

Synthesizing large metal-organic framework (MOF) single crystals has garnered significant research interest, although it is hindered by the fast nucleation kinetics that gives rise to numerous small nuclei. Given the different chemical origins inherent in various types of MOFs, the development of a general approach to enhancing their crystal sizes presents a formidable challenge. Here, we propose a simple isotopic substitution strategy to promote size growth in MOFs by inhibiting nucleation, resulting in a substantial increase in the crystal volume ranging from 1.7- to 165-fold. Impressively, the crystals prepared under optimized conditions by normal approaches can be further enlarged by the isotope effect, yielding the largest MOF single crystal (2.9 cm × 0.48 cm × 0.23 cm) among the one-pot synthesis method. Detailed in situ characterizations reveal that the isotope effect can retard crystallization kinetics, establish a higher nucleation energy barrier, and consequently generate fewer nuclei that eventually grow larger. Compared with the smaller crystals, the isotope effect-enlarged crystal shows 33% improvement in the X-ray dose rate detection limit. This work enriches the understanding of the isotope effect on regulating the crystallization process and provides inspiration for exploring potential applications of large MOF single crystals.

The Gnostic Code

Purpose: The aim of the study was to the gnostic code.
 Materials and Methods: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries.
 Findings: The Gnostic parables excerpted above are sufficient to establish that a code was functioning in these documents. By using coded language, the parables obscured a functioning message beneath the veneer of a spiritual or otherwise unintelligible narrative. In multiple textual exchanges, the concept substitution method allows literal and relevant messages to be derived from the text. The literal translations utilize terms from the binary cipher in ways that are clearly out of context. The paragraphs do not make literal sense because of these consistent terms. When the encoded definitions are applied instead of the literal definitions, a new and intelligible message is revealed.
 Implications to Theory, Practice and Policy: It will only be a matter of time before the evidence accumulates to prove that the Gnostic code is real. When the simple substitution code described in this manuscript is applied to the documents in the Nag Hammadi library, it becomes impossible not to see that the code functions. The confu-sion over Gnosticism is understandable considering how far conventional wisdom has to travel in order to appreciate the documents. A consistent code was used by enemies of the Roman Empire in order to hide messages within texts in order to hide their plans.

A Critical Analysis of the Modern Synthetic Procedures Used to Produce Benzimidazole Candidates

Background:: Benzimidazole is a remarkable heterocyclic chemical compound in which the phenyl ring is fused with the imidazole ring at positions 4 and 5. Benzimidazole derivatives have lots of medicinal activity in the pharmaceutical industry. Therefore, the synthesis of benzimidazole derivatives is challenging in this scientific field. Methods:: In benzimidazole synthesis, simple nucleophilic substitution and condensation reactions involving carbonyl compounds and o-phenylenediamine have been used in previous times. Currently, green chemistry aspects such as solvent-free conditions, metal-free conditions, or using nanoparticle catalysts in various ways involving condensation, and cyclization are the methods of the new era. Results:: Green chemistry methods are used widely in various chemical reactions, such as it was observed that the use of solvent-free conditions, metal-free conditions, or using nanoparticle catalysts molecules is a more efficient way to synthesize benzimidazole derivative. Conclusion:: In this review, benzimidazole scaffold syntheses that have only recently been described in the literature through the end of 2021 are covered. Monosubstituted benzimidazoles (MSBs) and disubstituted-benzimidazoles (DSBs) are the primary targets of our research currently. Different ways have been found to make functionalized derivatives of benzimidazole, which are shown in this review as a powerful scaffold.

Highly Ordered Mesoporous Polymer‐Supported Phosphine as the Ligand for Organometallic Reaction: Suzuki‐Miyaura Cross‐Coupling of Aryl Chlorides at Room Temperature

AbstractWe prepared a highly ordered mesoporous polymer‐supported diarylphosphine ligand by simple substitution reaction. By utilizing this ligand, we successfully achieved the Suzuki‐Miyaura cross‐coupling of various aryl chlorides at room temperature with high yields. Also, we extended our investigation to the use of a macroporous polymer support in a similar way, which yielded effective Suzuki‐Miyaura cross‐coupling reactions of both aryl chlorides and hindered aryl bromides.

Developing messages to encourage healthy, sustainable dietary substitutions: A qualitative study with US emerging adults

Prior research shows that adopting simple dietary substitutions (e.g., replacing beef with poultry or plant-based entrees) can improve dietary quality and reduce the negative environmental consequences of food production, but little is known about how to encourage people to adopt these substitutions. This study aimed to examine reactions to messages encouraging healthy, sustainable dietary substitutions among emerging adults ages 18–25. We conducted four online focus groups with a diverse sample of US emerging adults (n = 28; 61% female). Focus groups explored emerging adults’ reactions to messages encouraging them to adopt three target dietary substitutions: replacing beef and pork with poultry and plant-based entrees; replacing juice with whole fruit; and replacing dairy milk with non-dairy milk. We transcribed discussions verbatim and adopted a thematic approach to analyzing the transcripts. Results showed that participants perceived messages to be most effective at encouraging the target dietary substitutions when the messages: encouraged specific, achievable dietary changes; linked these dietary changes to clear consequences; included personally relevant content; included statistics; were succinct; and used a positive tone. Across the target dietary substitutions, two message topics (small changes, big benefits, which emphasized how small dietary changes can have large positive health and environmental impacts, and warning, which discussed the negative health and environmental impacts of dietary choices) were generally perceived to be most effective. A few participants expressed doubt that the target dietary substitutions would have meaningful environmental impacts. Results suggest that campaign messages to encourage healthy, sustainable dietary substitutions may be more effective if the messages make the target dietary substitutions seem achievable and use statistics to clearly describe the positive impacts of making these changes.

Programmable DNA tweezers-SDA for ultra-sensitive signal amplification fluorescence sensing strategy

BackgroundDNA tweezers, classified as DNA nanomachines, have gained prominence as multifunctional biosensors due to their advantages, including a straightforward structure, response mechanism, and high programmability. While the DNA tweezers demonstrate simultaneous, rapid, and stable responses to different targets, their detection sensitivity requires enhancement. Some small molecules, such as mycotoxins, often require more sensitive detection due to their extremely high toxicity. Therefore, more effective signal amplification strategies are needed to further enhance the sensitivity of DNA tweezers in biosensing. ResultsWe designed programmable DNA tweezers that detect small-molecule mycotoxins and miRNAs through simple sequence substitution. While the DNA tweezers demonstrate simultaneous, rapid, and stable responses to different targets, their detection sensitivity requires enhancement. We introduced the Strand Displacement Amplification (SDA) technique to address this limitation, proposing a strategy of novel programmable DNA tweezers-SDA ultrasensitive signal amplification fluorescence sensing. We specifically investigate the effectiveness of this approach concerning signal amplification for two critical mycotoxins: aflatoxin B1 (AFB1) and zearalenone (ZEN). Results indicate that the detection ranges of AFB1 and ZEN via this strategy were 1–10,000 pg mL −1 and 10–100,000 pg mL −1, respectively, with corresponding detection limits of 0.933 pg mL −1 and 1.07 pg mL −1. Compared with the DNA tweezers direct detection method for mycotoxins, the newly constructed programmable DNA tweezers-SDA fluorescence sensing strategy achieved a remarkable 104-fold increase in the detection sensitivity for AFB1 and ZEN. SignificanceThe constructed programmable DNA tweezers-SDA ultrasensitive signal-amplified fluorescence sensing strategy exhibits excellent detection performance for mycotoxins. The superb versatility of this strategy allows the developed method to be easily used for detecting other analytes by simply replacing the aptamer and cDNA, which has incredible potential in various fields such as food safety screening, clinical diagnostics, and environmental analysis.