Resilience of DNA chains to molecular fracture after PCR heating cycles and implications on PCR reliability.

Soon after its introduction in 1987, polymerase chain reaction (PCR) has become a technique widely employed in diagnostic medical devices and forensic science with the intention of amplifying genetic information. PCR prescribes that each of its cycles must include a heating subprocess at 95 °C or more (denominated DNA denaturation and provided for allowing a claimed orderly separation of the two complementary nucleotides strands), which can produce significant damage to DNA, caused by high-speed collisions with surrounding molecules. Since such disruption should be prevented in order to reliably employ PCR, a study of the mechanics of such loss of structural integrity is herein presented, preceded by a review of the fundamental literature which has elucidated the effects of molecular agitation on DNA fragmentation. The main conclusion of this retrospective survey is that the body of examined theoretical and experimental evidence consistently and redundantly confirms scarce resilience and significant loss of structural integrity when DNA is heated at temperatures above 90 °C, even for 1 minute. Such conclusion contradicts the claimed paradigm of PCR fidelity and raises the concern that, at least for long sequences, if PCR can amplify some information, such amplified information may be unreliable for diagnostic or forensic applications, since it originates from sequences of nucleotides subjected to random fragmentation and reaggregation. Such a low-reliability scenario should be preventively considered in the various fields where DNA amplification methodologies are employed which provide for high-temperature heating under conditions equal to or similar to those prescribed by the PCR protocols reviewed in this study.

Alkyl sulfones: discovery of novel structural types with differentiated opportunities for insect control.

The discovery of novel chemical classes with novel modes of action for insect control form the backbone of innovation with the goal to deliver much-needed solutions into the hands of growers. Over the last decade, alkyl sulfones have emerged as one of the most versatile new classes and are under intensive investigation in many R&D programs in the industry, with Sumitomo Chemicals recently introducing oxazosulfyl as a first active ingredient to the market. In this review, we discuss some of our strategies to invent novel classes based upon ligand-based design, and also show how incorporation of physical chemical properties into our design enabled us to predictably control chewing and sucking pests. © 2024 Society of Chemical Industry.

Physical Chemistry Lab for Data Analysis of COVID-19 Spreading Kinetics in Different Countries.

The COVID-19 pandemic has passed. It gives us a real-world example of kinetic data analysis practice for our undergraduate physical chemistry laboratory class. It is a great example to connect this seemingly very different problem to the kinetic theories for chemical reactions that the students have learned in the lecture class. At the beginning of the spring 2023 semester, we obtained COVID-19 kinetic data from the "Our World in Data" database, which summarizes the World Health Organization (WHO) data reported from different countries. We analyzed the effective spreading kinetics based on the susceptible-infectious-recovered-vaccinated (SIR-V) model. We then compared the effective rate constants represented by the real-time reproduction numbers ( R t ) underlining the reported data for these countries and discussed the results and the limitations of the model with the students.

Investigation on Fermented Milk Quality after the Addition of Flaxseed Mucilage and the Use of Lactobacillus delbrueckii subsp. bulgaricus and Lactiplantibacillus plantarum AG9.

BACKGROUND: Flaxseed mucilage (FSM) is one of the healthy components of flaxseed. FSM is an example of a material that can be used in the food, cosmetic, and pharmaceutical industries due to its rheological properties. FSM consists mainly of two polysaccharides, arabinoxylan, and rhamnogalacturonan I, and it also contains protein components and minerals. The prospect of using FSM in food is due to its gelling, water binding, emulsifying, and foaming properties. In addition, valuable natural sources of phenolic compounds such as lignans, phenolic acids, flavonoids, phenylpropanoids, and tannins are partially extracted from flaxseed in FSM. These antioxidant components have pharmacological properties, including anti-diabetic, anti-hypertensive, immunomodulatory, anti-inflammatory and neuroprotective properties. A combination of FSM and lactobacilli in dairy foods can improve their functional properties. This study aimed to develop dairy products by adding of FSM and using two lactic acid bacteria (LAB). FSM (0.2%) was used as an ingredient to improve both the texture and antioxidant properties of the product. METHODS: Skim milk was fermented with 0.2% flaxseed mucilage using Lactobacillus delbrueckii subs. bulgaricus and the probiotic Lactiplantibacillus plantarum AG9. The finished fermented milk products were stored at 4 °C for 14 days. Quantitative chemical, textural, and antioxidant analyses were carried out. RESULTS: Adding 0.2% FSM to the dairy product stimulated the synthesis of lactic acid. FSM increased the viscosity and water-holding capacity of L. bulgaricus or L. bulgaricus/L. plantarum AG9 fermented milk products. Combining these starter strains with FSM promoted the formation of a hard, elastic, resilient casein matrix in the product. When only L. plantarum AG9 was used for the fermentation, the dairy product had a high syneresis and a low viscosity and firmness; such a product is inferior in textural characteristics to the variant with commercial L. bulgaricus. The addition of FSM improved the textural properties of this variant. The use of L. plantarum AG9 and FSM makes it possible to obtain a fermented milk product with the highest content of polyphenolic compounds, which have the highest antioxidant properties and stimulate lipase and α-glucosidase inhibitor synthesis. Combining of L. bulgaricus and L. plantarum AG9 in the starter (20% of the total mass of the starter) and adding of 0.2% FSM is the optimal combination for obtaining a dairy product with high textural and antioxidant properties. CONCLUSIONS: The physicochemical properties (viscosity, syneresis, water holding capacity, texture) and antioxidant properties of fermented milk were improved. In the future, as part of the work to investigate the functional properties of dairy products with FSM, studies will be conducted using in in vivo models.

Cavitation is the determining mechanism for the atomization of high-viscosity liquid.

Piezoelectric atomization is becoming mainstream in the field of inhalation therapy due to its significant advantages. With the rapid development of high-viscosity gene therapy drugs, the demand for piezoelectric atomization devices is increasing. However, conventional piezoelectric atomizers with a single-dimensional energy supply are unable to provide the energy required to atomize high-viscosity liquids. To address this problem, our team has designed a flow tube internal cavitation atomizer (FTICA). This study focuses on dissecting the atomization mechanism of FTICA. In contrast to the widely supported capillary wave hypothesis, our study provides evidence in favor of the cavitation hypothesis, proving that cavitation is the key to atomizing high-viscosity liquids with FTICA. In order to prove that the cavitation is the key to atomizing in the structure of FTICA, the performance of atomization is experimented after changing the cavitation conditions by heating and stirring of the liquids.

The interaction between formylphenoxyacetic acid derivatives (chalcone and flavones) and ionic surfactants: Insights into binding constants, solubilisation and physiochemical properties.

In this study, UV-vis spectroscopy was employed to investigate the interaction between formylphenoxyacetic acid (FPAA) and its derivatives (chalcone and flavones) with ionic surfactants (SDS, CTAB, and DTAB) in different physiological environments. Changes in the physiochemical properties of FPAA chalcone and flavones including binding constants, partitioning constants, and Gibbs free energy were observed which were influenced by the presence of ionic surfactants computed using mathematical models. The solubilization of the targeted compounds in the ionic surfactants was determined through the binding constant (Kb). The results of the present study indicated that electrostatic interactions played a significant role in the solubilization of the targeted compounds in SDS, CTAB, and DTAB. At pH 4.1, FPAA chalcone exhibited stronger binding affinity with SDS compared to CTAB and DTAB. However, at pH 7.4, chalcone showed stronger binding with DTAB compared to SDS, while negligible interaction with CTAB was observed at pH 7.4. The flavones demonstrated stronger binding with DTAB at pH 7.4 compared to SDS and CTAB and it exhibited strong bonding with CTAB at pH 4.1. The negative values of the Gibbs free energy for binding (ΔGb˚) and partitioning (ΔGp˚) constants displayed the spontaneity of the process. However, FPAA chalcone with SDS and FPAA flavones with DTAB furnished positive ΔGb˚, indicating a non-spontaneous process.

A feasible interlayer strategy for simultaneous light and heat management in photothermal catalysis.

Photothermal conversion represents one crucial approach for solar energy harvesting and its exploitation as a sustainable alternative to fossil fuels; however, an efficient, cost-effective, and generalized approach to enhance the photothermal conversion processes is still missing. Herein, we develop a feasible and efficient photothermal conversion strategy that achieves simultaneous light and heat management using supported metal clusters and WSe2 interlayer toward enhanced CO2 hydrogenation photothermal catalysis. The interlayer can simultaneously reduce heat loss in the catalytic layer and improve light absorption, leading to an 8-fold higher CO2 conversion rate than the controls. The optical and thermal performance of WSe2 interlayered catalysts on different substrates was quantified using Raman spectroscopy. This work demonstrates a feasible and generalized approach for effective light and heat management in solar harvesting. It also provides important design guidelines for efficient photothermal converters that facilitate the remediation of the energy and environmental crises faced by humans.

Application of metal-organic frameworks and their derivates for thermal-catalytic C1 molecules conversion.

One-carbon (C1) catalysis refers to the conversion of compounds with a single carbon atom, especially carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4), into clean fuels and valuable chemicals via catalytic strategy is crucial for sustainable and green development. Among various catalytic strategies, thermal-driven process seems to be one of the most promising pathways for C1 catalysis due to the high efficiency and practical application prospect. Notably, the rational design of thermal-driven C1 catalysts plays a vital role in boosting the targeted products synthesis of C1 catalysis, which relies heavily on the choice of ideal active site support, catalyst fabrication precursor, and catalytic reaction field. As a novel crystalline porous material, metal-organic frameworks (MOFs) has made significant progress in the design and synthesis of various functional nanomaterials. However, the application of MOFs in C1 catalysis faces numerous challenges, such as thermal stability, mechanical strength, yield of MOFs, and so on. To overcome these limitations and harness the advantages of MOFs in thermal-driven C1 catalysis, researchers have developed various catalyst/carrier preparation strategies. In this review, we provide a concise overview of the recent advancements in the conversion of CO, CO2, and CH4 into clean fuels and valuable chemicals via thermal-catalytic strategy using MOFs-based catalysts. Furthermore, we discuss the main challenges and opportunities associated with MOFs-based catalysts for thermal-driven C1 catalysis in the future.

A facile method for separating fine water droplets dispersed in oil through a pre-wetted mesh membrane.

To achieve the successful separation of emulsions containing fine dispersed droplets and low volume fractions, a membrane with pore sizes comparable to or smaller than the droplet size is typically required. Although this approach is effective, its utilization is limited to the separation of emulsions with relatively large droplets. To overcome this limitation, a secondary membrane can be formed on the primary membrane to reduce pore size, but this can also be time-consuming and costly. Therefore, a facile and effective method is still required to be developed for separating emulsions with fine droplets. We introduce a pre-wetted mesh membrane with a pore size significantly larger than droplets, easily fabricated by wetting a hydrophilic stainless-steel mesh with water. Applying this membrane to emulsion separation via gravity-driven flow confirms a high efficiency greater than 98%, even with droplets approximately 10 times smaller than the pore size.

The pivotal role of bromine in FeMnKBr/YNa catalyst for CO2 hydrogenation to light olefins.

Light olefins are key intermediates in the synthesis of petrochemicals, and the conversion of stabilized carbon dioxide to light olefins using catalysts containing halogenated elements such as chlorine is a major challenge. Building on previous reports emphasizing the toxic effects of halogen elements on catalysts, we present the synthesis of FeMnKBr/YNa catalysts. This involved the synthesis of the catalyst by melt permeation using Br-containing potassium salts, other metal nitrates and YNa zeolites. The catalyst performed well in converting syngas (H2/CO2 = 3) to light olefins with a selectivity of 56.2%, CO2 conversion of 34.4%, and CO selectivity of 13.6%. Adding Br aids in reducing the Fe phase, boosts catalyst carburization, and produces more iron carbide species. It also moderately deposits carbon on the active center's surface, enhancing active phase dispersion. Br's electronegativity mitigates the influence of K, reducing catalyst's carbon-carbon coupling ability, leading to more low-carbon olefins generation.

Mechanism insight into the N-C polar bond and Pd-Co heterojunction for improved hydrogen evolution activity.

Constructing platinum-like materials with excellent catalytic activity and low cost has great significance for hydrogen evolution reaction (HER) during electrolysis of water. Herein, palladium nanoparticles (NPs) deposition on the surface of Co NPs using nitrogen-doped carbon (NC) as substrate, denoted as N-ZIFC/CoPd-30, are manufactured and served as HER electrocatalysts. Characterization results and density functional theory calculations validate that Pd-Co heterojunctions with NC acting as "electron donators" promote the Pd species transiting to the electron-rich state based on an efficient electron transfer mechanism, namely the N-C polar bonds induced strong metal-support interaction effect. The electron-rich Pd sites are beneficial to HER. Satisfactorily, N-ZIFC/CoPd-30 have only low overpotentials of 16, 162, and 13 mV@-10 mA cm-2 with the small Tafel slopes of 98 mV/decade, 126 mV/decade, and 72 mV/decade in pH of 13, 7, and 0, respectively. The success in fabricating N-ZIFC/CoPd opens a promising path to constructing other platinum-like electrocatalysts with high HER activity.

Oxygen vacancy enhanced photocatalytic activity of Cu2O/TiO2 heterojunction.

In this study, a method was developed to create oxygen vacancies in Cu2O/TiO2 heterojunctions. By varying the amounts of ethylenediaminetetraacetic acid (EDTA), sodium citrate, and copper acetate, Cu2O/TiO2 with different Cu ratios were synthesized. Tests on CO2 photocatalytic reduction revealed that Cu2O/TiO2's performance is influenced by Cu content. The ideal Cu mass fraction in Cu2O/TiO2, determined by inductively coupled plasma (ICP), is between 0.075% and 0.55%, with the highest CO yield being 10.22 µmol g-1 h-1, significantly surpassing pure TiO2. High-resolution transmission electron microscopy and electron paramagnetic resonance studies showed optimal oxygen vacancy in the most effective heterojunction. Density functional theory (DFT) calculations indicated a 0.088 eV lower energy barrier for ∗CO2 to ∗COOH conversion in Cu2O/TiO2 with oxygen vacancy compared to TiO2, suggesting that oxygen vacancies enhance photocatalytic activity.

1,3-diene-based AIEgens: Stereoselective synthesis and applications.

In recent years, significant advancements have been made in the synthesis and application of 1,3-dienes. This specific structural motif has garnered significant attention from researchers in materials science and biology due to its unique aggregation-induced emission (AIE) properties and extensive conjugation systems. The luminescent characteristics of these compounds are notably influenced by the geometry of the two double bonds. Therefore, it is essential to consolidate stereoselective synthetic strategies for 1,3-dienes. This comprehensive review seeks to elucidate the diverse techniques employed to attain stereo-control in the synthesis of 1,3-diene-based AIE luminogens (AIEgens). Particular emphasis is placed on comprehending the determinants of stereoselectivity and exploring the array of substrates amenable to these methods. Furthermore, the review underscores the AIE properties exhibited by these compounds and their extensive utility in organic light-emitting diodes (OLEDs), stimuli-responsive materials, sensors, bioimaging, and photodynamic therapy (PDT).

Phase Transitions in Organic and Organic/Inorganic Aerosol Particles.

The phase state of aerosol particles can impact numerous atmospheric processes, including new particle growth, heterogeneous chemistry, cloud condensation nucleus formation, and ice nucleation. In this article, the phase transitions of inorganic, organic, and organic/inorganic aerosol particles are discussed, with particular focus on liquid-liquid phase separation (LLPS). The physical chemistry that determines whether LLPS occurs, at what relative humidity it occurs, and the resultant particle morphology is explained using both theoretical and experimental methods. The known impacts of LLPS on aerosol processes in the atmosphere are discussed. Finally, potential evidence for LLPS from field and chamber studies is presented. By understanding the physical chemistry of the phase transitions of aerosol particles, we will acquire a better understanding of aerosol processes, which in turn impact human health and climate.