Specific Chemical Bonds Research Articles

Synergistic degradation of refractory organic pollutant by underwater bubbling plasma combined with heterogeneous Fenton process

Excessive discharge of the refractory organic pollutants endangers the development of the society and economy, thus seeking an efficient wastewater abatement method is an urgent need. Herein, Iron (Ⅱ) sulfide (FeS) was employed as the heterogeneous catalyst and coupled with underwater bubbling plasma (UBP) for the elimination of the refractory organic pollutant, malachite green (MG). FeS catalyst was synthesized using the solvothermal method and subsequently characterized comprehensively, focusing on its microstructure, specific surface area, chemical bonds and elements valence states. The UBP system combined with FeS (UBP/FeS) exhibited the robust synergism with a maximum synergistic factor of 1.89. The MG degradation percentage and rate constant were up to 94.7% and 0.237 min−1 within 12 min. The parameter experiments revealed that FeS dosage, pulse frequency, initial MG concentration and solution conductivity of 150 mg/L, 56 Hz, 5 mg/L and 21.8 μS/cm, respective, were more conducive for MG elimination. The MG removal efficiency reached 86.2% after five consecutive applications of FeS. Reactive substances including ·OH, ·O2−, eaq, O3 and H2O2 were confirmed to contribute to MG elimination. Additionally, the conversion circle between ≡ Fe(Ⅱ) and ≡ Fe(Ⅲ) promoted the catalytic conversion of H2O2 and O3 into ∙OH. The comparison of UV–vis spectra and total organic carbon of MG solution before and after reaction revealed the superior degradation of MG in the UBP/FeS system. Hypotheses regarding to the decomposition pathways of MG were formulated based on the identified intermediates. The toxicity level of MG solution was lightened after reaction. The above results indicate that UBP/FeS has the advantages of quick degradation and high efficiency, representing a promising approach for refractory pollutants treatment.

Insight into the Pyrolysis Behaviors of Petroleum-Driven Mesophase Pitch via ReaxFF Molecular Dynamics and In Situ TG-FTIR/MS.

Mesophase pitch is regarded as a profoundly promising candidate for the production of advanced carbon-based multifunctional materials such as carbon fibers, carbon microspheres, and carbon foams owing to its excellent intrinsic properties. Consequently, a deeper understanding of pyrolytic chemistry is indispensable for the efficient and environmentally friendly utilization of mesophase pitch. In this study, details about the structure compositions and microscopic morphologies of petroleum-driven mesophase pitch (pMP) were investigated through ultimate, FTIR, XPS, and 13C-NMR analyses. Furthermore, a large-scale molecular model of typical pMP with 11,835 atoms was constructed to unveil the comprehensive pyrolysis behaviors and the underlying reactions. Significantly, the evolution of specific chemical bonds and the decomposition of crucial molecular fragments were elucidated within an amalgamation of experimental TG-FTIR/MS and ReaxFF MD simulation. Accordingly, three fundamental reaction stages were artificially divided, including the low-temperature reaction, rapid thermal decomposition, and the molecular condensation reaction. During the rapid thermal decomposition stage, the cleavages of C-C and C-O bonds cooperatively contributed to the formation of C2H4 and H2O gaseous products. As the temperature escalated to the molecular condensation stage, the pyrolysis process was governed by the dehydrogenation condensation, accompanied by an augmentation of C-C and H-H bonds and a diminution of C-O and C-H bonds. Additionally, the rare graphitization phenomenon was observed, suggesting a remarkable degree of structural organization in pMP. Overall, the results of ReaxFF MD simulations complement experimental observations, successfully reproducing the microstructure of pMP and atomic-scale pyrolysis behavior, thereby providing invaluable insights for the rational guidance of efficient utilization of pMP and other related carbonaceous precursors.

(Digital Presentation) The Intermediate Electron Bond. Half-Reactions and the Electronic Structure of Atoms

The transfer of electrons ne from the intermediate state (Ox1 ← ne → Ox2) is associated with formation of a chemical bond with one Ox-form. Consequently, chemical bonds of electrons with Ox - forms should be formed Ox + ne + H2O→ Red or broken Red + H2O → Ox + ne in half-reactions. Then, there should be concluded some electronic state and bond without a specific chemical component. This electronic bond was determined as a definite coulomb bond, intermediate from metallic to non-metallic specific bonds. Ionization potential of intermediately bound electrons is determined I interm. = 5.19 eV [1-4].The chemical energy released in half-reactions-interactions is spent at once on separation of formed oppositely charged electrons and ions, polarization of water molecules of formed intermediate complexes. External potential differences appear between charged particles (double layers). Electrons and ions acquire electrochemical potentials, and electrochemical equilibriums are established.Exchange of formed electrons with electrons of electrodes stabilizes half-reactions. At that, a contact potential drop (not associated with interaction) appears in the electrode surface. However, only potential drops in double layers need to be taken into account. The rates of half-reactions-interactions change with changes in potential drops in double layers during electrical polarization.An important determination of ionization energy I interm. = 5.19 eV based on the found linear relationships between the first ionization potentials I of elements (related to the main groups) and their reversal covalent atomic radii 1/ r atom (Fig. 1). The linear relations cross when I interm. = 5.19 eV at 1/ r atom = 0.35 Ằ-1 ( r atom = 2.79 Ằ). It is concluded, that a specific electron bond formation with wave overlap begins with r atom = 2.79 Ằ at I interm. = 5.19 eV. Taking r interm. = 2.79 Ằ, ionization potential I interm. was calculated as coulomb energy of attraction between electron and polarized positive charge on Ox - form [2 - 4] I interm. =- e 2/ r interm. = - (4.8.10-10 e.s.u.)2 / 1.6.10-12 erg/eV . r interm. .10-8 cm == - 14.4 . 10-8eV.cm/2.79.10-8cm = - 5.19 eV (1)According to linear relations (Fig.1), for similar elements, the first ionization potentials I are equal I = 5.19 eV + Δ I (2)when energies of formation of specific electronic bonds Δ I are changed by quanta. The quantum linear oscillator model is applied Δ I = (Δ n + ½) h ν o (3)where h is Plank constant, ν o is the natural frequency of electron - wave, Δ n are numbers of quantum jumps, Δ I = ½ hν o is the point zero energy [4,5].It is concluded, that quantum jumpsΔ n = 8 - n = 1, 2, 3... should be counted from the orbital n = 8 on which electron localization and specific bonding is absent (8th period is absent in the Periodic System). However, the coulomb non-specific electronic bonding ( I interm. = 5.19 eV) must be preserved (Figh.1). Indeed, the first ionization potentials of elements of the 7th period are ~ 5 eV (5.17 eV for Ac).Therefore, Δ n = 1, Δ n = 2, Δ n = 3 ... correspond to one, two, three electron jumps necessary to reach the localization orbital related to the 7th, 6th, 5th .... (and so on) periods. First, using these Δ n , close natural frequencies ν o of electron waves were calculated for similar atoms as ν o = I - 5.19 eV / (Δ n + ½) h (4)For example, calculated ν o are for I (0.364.1015 s-1), Br (0.358.1015 s-1), Cl (0.344.1015 s-1), F (0.347 .1015 s-1).Using even the average natural frequency (0.35.1015 s-1), the first ionization potentials I (close to reference) were then calculated as the sums (Eqn.2). I = 5.19 eV + Δ I = 5.19 eV + (Δ n + ½) hν o (5)for most of elements. For example, for elements of the 7th main groups: I 10.3 eV (10.4 eV), Br 11.75 eV (11.8 eV), Cl 13.1 eV (13.0 eV), F 17.5 eV (17.4 eV). Emission wavelengths are also determined [4].Therefore, the quantum-mechanical oscillator model can be applied to electron localization in atoms and to formation and breaking of specific chemical electron bonds with Ox - forms in half-reactions. In both cases, electron - waves pass to (or from) the intermediate state I interm. = 5.19 eV corresponding to the absence of specific bond formation. References A.I Chernomorskii, Russian Journal of Physical Chemistry, 55(2)1981.A.I. Chernomorskii, Thermodynamics of Electrodes (FAN,Tashkent,1993);A.I Chernomorskii, Journal of The Electrochemical Society, 2021, 168, 116514A.I Chernomorskii, The intermediate electron bond and half-reactions (Scientific Resources, N-Y) (1999).P. Atkins, Julio de Paula, Physical Chemistry (W.H. Freeman and company,2006). Figure 1

Assembling, Computational and Experimental Insight of Self-assembled Carbo Benzyl oxy-L-Alanyl-L-Valine Benzyl Ester: A Novel Free Radical Scavenger and Photo Therapeutic Nano Molecular System

Introduction: This work investigates the synthesis of self-assembled novel carbo benzyl oxy - L - alanyl - L - valine benzyl ester (CBAVBE). Methods: Thorough studies of the morphology, optical, and structural investigations by UV-Visible, UV-DRS, FT-IR, FT-Raman, HR-TEM, and FE-SEM are used to characterize the self-assembled CBAVBE and computational studies also investigated. The anti-oxidant capability of carbo benzyl oxy - L - alanyl - L - valine benzyl ester is evaluated after self-assembly. Results: FT-IR and Raman analysis have proven that specific chemical bonds exist in the self-assembled CBAVBE. FE-SEM analysis clearly confirms that the CBAVBE is fibrous in nature, and the collected images clearly show the CBA assembly VBE to be well aggregated. The docking analysis suggests that the CBAVBE molecule has inhibitory action against brain and lung cancer protein but biological study is needed to validate the results. An antioxidant study reveals the potential of the selected CBAVE as a notable biomarker. Conclusion: A new class of self-assembled peptide nano self-assemblies have been marked as a discovery that could be used to treat a variety of diseases.

Photocatalytic Degradation of Toxic Rhodamine B Dye by Green‐Synthesised Activated Carbon‐Supported Cobalt Doped ZnO With Further Assessment of ZnO Nanoparticles in Antimicrobial Applications

AbstractThis work investigates the synthesis of ZnO nanoparticles, cobalt (Co)‐doped ZnO, and Activated Carbon (AC) ‐Co doped ZnO via green precipitation technique. AC developed from lotus stems and precipitated by lotus leaf extract. Comprehensive structural, optical, and morphological investigations by FT‐IR, XRD, FE‐SEM, EDX, HR‐TEM, UV‐DRS, PL, and XPS studies are used to characterize the photocatalysts. The ZnO nanoparticles are shown to have a hexagonal phase by XRD examination. The results of the FT‐IR analysis proved that specific chemical bonds exist in the ZnO, Co−ZnO, and AC−Co‐doped ZnO nanocomposites. FE‐SEM images revealed spherical morphology with aggregated, randomly distributed particles with an average size range of ZnO, Co−ZnO and AC−Co−ZnO are 59.55, 42.55, 41.16 nm. The band gap energies of ZnO, Co ‐ZnO, and AC−Co‐ ZnO, are found to be 3.10, 2.57, and 1.94 eV, respectively. Rhodamine B is used as a model contaminant to assess the samples under UV‐light driven photocatalytic effectiveness. The photocatalytic degradation efficiency (%) of the pristine ZnO, Co‐doped ZnO, and AC−Co‐doped ZnO catalysts are increased to 61.76, 74.86, and 91.46 % after 140 minutes of under UV‐light irradiation. Degradation rate constant (k) of the AC−Co−ZnO photocatalyst is found to be greater than that of pristine ZnO and Co−ZnO. Due to the synergistic effect of the AC and Co metal dopants and the spherical morphology of the AC−Co−ZnO sample, which boosted UV‐visible light absorption with reduced charge carrier recombination, resulting in outstanding photocatalytic activity. The study also investigated the bioactive effect of the samples on six bacterial species, revealing that the AC−Co‐doped ZnO nanocomposite has the most enhanced inhibitory effects against gram‐positive and gram‐negative bacteria. Consequently, medical wound dressing materials which helps to promote early healing by preventing microbial contamination.

Facile synthesis of DES-based functionalized Polyaniline@Fe3O4 magnetic microspheres for continuous and efficient dye removal: Properties and mechanism

Dyes are organic compounds that are necessary to impart color to substrates. Because methyl orange (MO) and methylene blue (MB) are difficult for the environment to biodegrade, it is critical that dyes be recycled quickly and efficiently. Herein, oxidation was used to create polyaniline@Fe3O4 nanorods (PANI@Fe3O4). Then, different types of deep eutectic solvents (DESs) were grafted to prepare several novel adsorption materials for green DESs-based magnetic nanomicrospheres (DESs-PANI@Fe3O4). The grafting of DESs not only increased the BET surface area (65.24 m2/g) of the adsorbent, provide a channel for rapid adsorption and efficient mass transfer of pollutants, but also provided abundant functionalized active sites (O-H, C = O, NH+) for efficient dye removal. Comparison of FTIR and XPS spectra before and after adsorption showed that specific functional groups (–OH, –NH2, –COOH) and functional chemical bonds (N-H, C-O, O-H) played an important role in rapid and effective dye removal. When grafted with ChCl-Lac as a green solvent, the adsorption capacity of the resulting ChCl-Lac-PANI@Fe3O4 for MO and MB dyes reached to 912.71 and 473.95 mg/g, respectively in a few minutes. Density functional theory (DFT) result showed that the adsorption was mainly promoted through π-π interaction, hydrogen bonding, and van der Waals interaction. In conclusion, DESs-PANI@Fe3O4 prepared by a facile strategy has the ability to remove dyes from wastewater continuously and efficiently, which provides a new concept for the industrial application of green DESs-based magnetic nanosphere adsorbent.

A study of surface fatigue wear and influence of contaminated lubricant in journal bearing system using tribological and vibration analyses

In the present work, journal bearing performance was evaluated using condition monitoring processes namely wear debris, vibration signal, lubricant oil degradation and temperature analyses. The journal bearing system was operated at 800 rpm and 200 N constant speed and load over a period of 1200 h. The lubricant oil samples were collected for every 300 h of test duration for oil degradation and wear particle analyses by using Fourier transform infrared radiation (FTIR) and scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDS) techniques, respectively. FTIR results provided specific chemical bonds and functional groups contained in the degraded oil. The vibration signals were acquired for every 100 h of operation, and a fast Fourier transform (FFT) frequency spectrum technique was employed for vibration signal analysis. The friction coefficient and specific wear rate parameters were considered to evaluate the tribological performance of the journal-bearing system. Statistical parameters, namely root-mean-square and kurtosis, were evaluated. Wear mechanisms such as abrasive, adhesive and surface fatigue wear were observed on the journal-bearing contact surfaces using a USB optical microscope. The scoring on the bearing element confirmed the fault development and resulted in an increase in vibration amplitudes. Higher mass loss in the bearing material was observed due to high friction and wear rates owing to its being a softer material than that of the journal material. The results obtained from the aforementioned parameter assessment techniques provided a reliable information on the defects which appeared on journal-bearing contact surfaces.

Fabrication and evaluating thermophysical properties of microencapsulated organic and eutectic phase change material

This study explores the synthesis and characterization of microencapsulation of organic and eutectic phase change materials with a melting point ranging from 5 to 30 ℃ for low-temperature applications. Emulsion polymerization utilizing methyl methacrylate monomer as the shell material is employed for effective encapsulation. Comprehensive characterization of microcapsules is undertaken, including chemical composition (using Fourier transform infrared (FT-IR) spectroscopy), morphology (employing scanning electronic microscopy (SEM) and metallurgical microscope), particle size distribution (measured by ImageJ software), enthalpy (evaluated through differential scanning calorimetry (DSC)) and thermal degradation (explored via thermogravimetric analysis (TGA)). The successful production of microencapsulated phase change materials (MPCM) is confirmed by their two-phase decomposition process, the presence of specific chemical bonds, and the spherical morphology of particles with an average diameter between 25.63 and 49.62 μm. However, in the case of eutectic core material, irregular microcapsules are shaped with a larger mean diameter. It has also affected the encapsulation efficiency in which around 29.43% and 30.1% efficiencies are reached for eutectic cores compared to 45.11% and 47% in organic ones. Simultaneously, thermophysical properties of MPCMs, such as density, thermal conductivity, and specific heat, are determined using the displacement method, transient line heat source, transient hot wire, and DSC. These properties are expressed through regression equations based on the determined effective factors. The derived equations enhance the capability to implement MPCMs in practical applications and numerical simulations.

Synergy of oxygen vacancy and Mn-substitution on SrTiO3 perovskites supported copper nanocatalysts for enhanced cyclohexylbenzene oxidation

Aiming at the main challenge of poor atomic economy for selective oxidation of hydrocarbons, synergistic catalysis on heterogenous catalysts has been focused on precisely regulating oxidation of specific chemical bonds in organic substrates. Here, a series of copper nanocatalysts loaded on Mn-substituted SrTiO3 perovskite-type oxides with varying Mn/Ti ratios for cyclohexylbenzene (CHB) oxidation to form cyclohexylbenzene-1-hydroperoxide (CHBHP) were successfully synthesized by coprecipitation method assisted by a micro-liquid-film reactor. It was found that the introduction of manganese created numerous oxygen vacancies in nanocatalysts, promoting the activation of oxygen molecules. Moreover, both copper and manganese ions enhanced the activated adsorption of CHB substrate. In particular, as-constructed Cu-based nanocatalyst with a substitution of 15% Mn into Ti sites showed superior catalytic oxidation efficiency with a ∼30% yield of CHBHP product, which is at the highest level compared with previously reported heterogenous catalysts, mainly attributable to the favorable synergy between copper, manganese, and oxygen vacancies. This work sheds light on the importance of multi-active site synergistic catalysis in advanced alkane oxidation processes.

Effect of mechanical energy input during mechanical crushing on the macrokinetics of the coal–oxygen reaction: A laboratory–scale study

Underground mining is usually simplified as a process of coal crushing and pulverization. However, this process is not purely physical. The mechanical energy input to this process also induces a mechanochemical effect. The specific impact of this effect on the macrokinetics of the coal–oxygen reaction (COR) has not been independently investigated, which motivates this work. Thermal analysis tests showed that mechanical energy input contributed to the strength of the COR and exhibited regularities in its impact on COR's kinetic parameters. Explanations for this were given based on mechanochemistry, free radicals chain reaction and quantum chemistry theories. A coal macromolecule model, influenced by mechanical energy input, was developed based on the typical Wiser model, and subsequent quantum mechanical calculations were conducted. It was found that mechanical energy input facilitated the breaking of specific chemical bonds in coal, redistributing the electrostatic potential and increasing the number of active sites within the coal molecule. Moreover, both the free radicals from bonds breaking and the remaining active structural sites exhibited an increasing trend in their electrified capacities. Different from the traditional physical pathway, this work refined the mechanism by which mechanical forces affect COR through the mechanochemical pathway.

Cleavage and Noncleavage Chemistry in Reactive Oxygen Species (ROS)-Responsive Materials for Smart Drug Delivery.

The design and development of advanced drug delivery systems targeting reactive oxygen species (ROS) have gained significant interest in recent years for treating various diseases, including cancer, psychiatric diseases, cardiovascular diseases, neurological diseases, metabolic diseases, and chronic inflammations. Integrating specific chemical bonds capable of effectively responding to ROS and triggering drug release into the delivery system is crucial. In this Review, we discuss commonly used conjugation linkers (chemical bonds) and categorize them into two groups: cleavable linkers and noncleavable linkers. Our goal is to clarify their unique drug release mechanisms from a chemical perspective and provide practical organic synthesis approaches for their efficient production. We showcase numerous significant examples to demonstrate their synthesis routes and diverse applications. Ultimately, we strive to present a comprehensive overview of cleavage and noncleavage chemistry, offering insights into the development of smart drug delivery systems that respond to ROS.

Enhancing forensic investigations: Identifying bloodstains on various substrates through ATR-FTIR spectroscopy combined with machine learning algorithms

The forensic analysis of bloodstains on various substrates plays a crucial role in criminal investigations. This study presents a novel approach for analyzing bloodstains using Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR) in combination with machine learning. ATR-FTIR offers non-destructive and non-invasive advantages, requiring minimal sample preparation. By detecting specific chemical bonds in blood components, it enables the differentiation of various body fluids. However, the subjective interpretation of the spectra poses challenges in distinguishing different fluids. To address this, we employ machine learning techniques. Machine learning is extensively used in chemometrics to analyze chemical data, build models, and extract useful information. This includes both unsupervised learning and supervised learning methods, which provide objective characterization and differentiation. The focus of this study was to identify human and porcine blood on substrates using ATR-FTIR spectroscopy. The substrates included paper, plastic, cloth, and wood. Data preprocessing was performed using Principal Component Analysis (PCA) to reduce dimensionality and analyze latent variables. Subsequently, six machine learning algorithms were used to build classification models and compare their performance. These algorithms comprise Partial Least Squares Discriminant Analysis (PLS-DA), Decision Trees (DT), Logistic Regression (LR), Naive Bayes Classifier (NBC), Support Vector Machine (SVM), and Neural Network (NN). The results indicate that the PCA-NN model provides the optimal solution on most substrates. Although ATR-FTIR spectroscopy combined with machine learning effectively identifies bloodstains on substrates, the performance of different identification models still varies based on the type of substrate. The integration of these disciplines enables researchers to harness the power of data-driven approaches for solving complex forensic problems. The objective differentiation of bloodstains using machine learning holds significant implications for criminal investigations. This technique offers a non-destructive, simple, selective, and rapid approach for forensic analysis, thereby assisting forensic scientists and investigators in determining crucial evidence related to bloodstains.

Excavating the Potential of Photo‐ and Electroupcycling Platforms Toward a Sustainable Future for Waste Plastics

Traditionally, waste plastics have been recycled using crude recycling processes, which pose serious environmental pollution and low recycling efficiency. The best option for managing waste plastics is to upgrade them into high‐value‐added chemicals by breaking down specific chemical bonds in plastic polymers. Herein, this article reviews recent representative research advancements in photo‐ and electrodegradation of plastics for obtaining small‐molecule, high‐value‐added chemicals. The focus is on the application and analysis of emerging technological processes and catalytic materials concepts in these upcycling pathways, with particular emphasis on the diverse functions exhibited by various catalysts. Through the optimization of plastic degradation processes with the rational design of degradation technical processes and catalysts, efficient and selective access to the target products, with the assistance of light and electrical energy with similar action principles, can be achieved. These efforts have yielded promising results, paving the way for resourceful plastic recycling. Particularly, the challenges that arise in upcycling of waste plastics are seriously discussed, and reasonable recommendations have been made to understand future developments and prospects in this research area. It is believed that photocatalysis and electrocatalysis, two emerging degradation methods, play an increasingly important role in the field of plastic upcycling.

Monooxygenases and Antibiotic Resistance: A Focus on Carbapenems.

Carbapenems are a group of broad-spectrum beta-lactam antibiotics that in many cases are the last effective defense against infections caused by multidrug-resistant bacteria, such as some strains of Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii. Resistance to carbapenems has emerged and is beginning to spread, becoming an ongoing public-health problem of global dimensions, causing serious outbreaks, and dramatically limiting treatment options. This paper reviews the role of flavin monooxygenases in antibiotic resistance, with a specific focus on carbapenem resistance and the recently discovered mechanism mediated by Baeyer-Villiger monooxygenases. Flavin monooxygenases are enzymes involved in the metabolism and detoxification of compounds, including antibiotics. Understanding their role in antibiotic resistance is crucial. Carbapenems are powerful antibiotics used to treat severe infections caused by multidrug-resistant bacteria. However, the rise of carbapenem-resistant strains poses a significant challenge. This paper explores the mechanisms by which flavin monooxygenases confer resistance to carbapenems, examining molecular pathways and genetic factors. Additionally, this paper highlights the discovery of Baeyer-Villiger monooxygenases' involvement in antibiotic resistance. These enzymes catalyze the insertion of oxygen atoms into specific chemical bonds. Recent studies have revealed their unexpected role in promoting carbapenem resistance. Through a comprehensive analysis of the literature, this paper contributes to the understanding of the interplay between flavin monooxygenases, carbapenem resistance, and Baeyer-Villiger monooxygenases. By exploring these mechanisms, it aims to inform the development of strategies to combat antibiotic resistance, a critical global health concern.

Exploring the cellular surface polysaccharide and root nodule symbiosis characteristics of the rpoN mutants of Bradyrhizobium sp. DOA9 using synchrotron-based Fourier transform infrared microspectroscopy in conjunction with X-ray absorption spectroscopy.

The functional significance of rpoN genes that encode two sigma factors in the Bradyrhizobium sp. strain DOA9 has been reported to affect colony formation, root nodulation characteristics, and symbiotic interactions with Aeschynomene americana. rpoN mutant strains are defective in cellular surface polysaccharide (CSP) production compared with the wild-type (WT) strain, and they accordingly exhibit smaller colonies and diminished symbiotic effectiveness. To gain deeper insights into the changes in CSP composition and the nodules of rpoN mutants, we employed synchrotron-based Fourier transform infrared (SR-FTIR) microspectroscopy and X-ray absorption spectroscopy. FTIR analysis of the CSP revealed the absence of specific components in the rpoN mutants, including lipids, carboxylic groups, polysaccharide-pyranose rings, and β-galactopyranosyl residues. Nodules formed by DOA9WT exhibited a uniform distribution of lipids, proteins, and carbohydrates; mutant strains, particularly DOA9∆rpoNp:ΩrpoNc, exhibited decreased distribution uniformity and a lower concentration of C=O groups. Furthermore, Fe K-edge X-ray absorption near-edge structure and extended X-ray absorption fine structure analyses revealed deficiencies in the nitrogenase enzyme in the nodules of DOA9∆rpoNc and DOA9∆rpoNp:ΩrpoNc mutants; nodules from DOA9WT and DOA9∆rpoNp exhibited both leghemoglobin and the nitrogenase enzyme. IMPORTANCE This work provides valuable insights into how two rpoN genes affect the composition of cellular surface polysaccharides (CSPs) in Bradyrhizobium sp., which subsequently dictates root nodule chemical characteristics and nitrogenase production. We used advanced synchrotron methods, including synchrotron-based Fourier transform infrared (SR-FTIR) microspectroscopy and X-ray absorption spectroscopy (XAS), for the first time in this field to analyze CSP components and reveal the biochemical changes occurring within nodules. These cutting-edge techniques confer significant advantages by providing detailed molecular information, enabling the identification of specific functional groups, chemical bonds, and biomolecule changes. This research not only contributes to our understanding of plant-microbe interactions but also establishes a foundation for future investigations and potential applications in this field. The combined use of the synchrotron-based FTIR and XAS techniques represents a significant advancement in facilitating a comprehensive exploration of bacterial CSPs and their implications in plant-microbe interactions.

Active Micelle Pumping Channel Triggers Nonequilibrium Surface Excess Aggregation.

Adsorbate transport during the electrochemical process mostly follows the electric-field direction or the high-to-low direction along the concentration gradient and thus often limits the reactant concentration at the adsorption site and requires specific mechanical or chemical bonds of adsorbates to trigger local excess aggregation for advanced framework structure assembly. Herein, we have discovered an active pumping channel during electrochemical adsorption of a manganese colloid, which follows a low-to-high direction inverse concentration gradient. It triggers surface excess micelle aggregation with even over 16-folds higher concentration than that in bulk owing to hydrogen-bonding difference of the micelle surface between in bulk and at the water surface. Micelles in the channel exhibit unique polymerization behaviors by directly polymerizing monomer micelles to form highly catalytic MnO2 of dendritic frameworks, which can serve as a scalable thin-layer aqueous-phase reactor. It increases the understanding of the interface-dependent dynamic nature of micelle or more adsorbates and inspires transformative synthesizing approaches for advanced oxide materials.

In Situ and Real-Time Mold Flux Analysis Using a High-Temperature Fiber-Optic Raman Sensor for Steel Manufacturing Applications

Continuous casting in steel production uses specially developed oxyfluoride glasses (mold fluxes) to lubricate a mold and control the solidification of the steel in the mold. The composition of the flux impacts properties, including basicity, viscosity, and crystallization rate, all of which affect the stability of the casting process and the quality of the solidified steel. However, mold fluxes interact with steel during the casting process, resulting in flux chemistry changes that must be considered in the flux design. Currently, the chemical composition of mold flux must be determined by extracting flux samples from the mold during casting and then processing these samples offline to estimate the working chemical composition and, therefore, the expected properties of the flux. Raman spectroscopy offers an alternative method for performing flux analysis with the potential to perform measurements online during the casting process. Raman spectroscopy uniquely identifies specific chemical bonds and symmetries in the glassy flux by revealing peaks that are a fingerprint of the vibration modes of molecules in the flux. The intensities of specific peaks in Raman spectra can be correlated with the chemical composition of the melt and associated properties such as basicity and viscosity. This paper reports on the first use of a portable fiber-optic Raman sensor for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> Raman spectroscopic measurements of molten flux at 1400°C. The work demonstrates the advantages of fiber-optic Raman spectroscopy to document the structure and chemical composition of flux samples at temperatures typically encountered in the mold during continuous caster operation. Experimental results demonstrate that the composition-dependent Raman signal shifts can be detected at caster operating temperatures, and the use of high-temperature Raman analysis for in-line flux monitoring shows significant promise for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> detection of changes in flux composition and physical properties during casting.

Properties of dentin, enamel and their junction, studied with Brillouin scattering and compared to Raman microscopy

ObjectiveDentin, enamel and the transition zone, called the dentin-enamel junction (DEJ), have an organization and properties that play a critical role in tooth resilience and in stopping the propagation of cracks. Understanding their chemical and micro-biomechanical properties is then of foremost importance. The aim of this study is to apply Brillouin microscopy on a complex biological structure, that is, the DEJ, and to compare these results with those obtained with Raman microscopy. DesignBoth techniques allow noncontact measurements at the microscopic scale. Brillouin microscopy is based on the interaction between acoustic phonons and laser photons and gives a relation between the frequency shift of the scattered light and the stiffness of the sample. Raman spectra contain peaks related to specific chemical bonds. ResultsComparison of the Brillouin and Raman cartographies reveals correlations between mechanical and chemical properties. Indeed, the shapes of the phosphate content and stiffness curves are similar. The two spectroscopies give compatible values for the mean distance between two tubules, i.e., 4–6 µm. Moreover, for the first time, the daily cross striations of enamel could be studied, indicating a relationship between the variation in the phosphate concentration and the variation in the rigidity within the enamel prisms. ConclusionsWe demonstrate here the possibility of using Brillouin scattering microscopy to both study complex biological materials such as the enamel-dentin junction and visualize secondary structures. Correlations between the chemical composition and mechanical properties could help in better understanding the tissue histology.

Bifunctional covalent triazine frameworks based on Ti-ON bonds for micropollutants removal: Effects of 3D extended structure and electron transport bridges

Adsorption-photocatalysis technology enables the enrichment of pollutants and the regeneration of materials, which is expected to control long-lasting organic micropollutants (OMPs) in water. In particular, taking the comprehensive advantages of composites to simultaneously improve the adsorption and photocatalytic performance is currently worth considering. Therefore, a kind of Ti/MDCTF composite with specific and strong chemical bonds (Ti-ON bonds) was synthesized by a facile approach. Compared with pristine MDCTF, 30 %-Ti/MDCTF showed an increased saturated adsorption capacity (440.56 μmol/g) and a 5.6-fold increase in photocatalytic degradation kinetic (0.315 h−1). It was comfirmed by homogenous surface diffusion model (HSDM) that the adsorption kinetics were controlled by the intra-particle diffusion. Additionally, 30 %-Ti/MDCTF exhibited a high photocatalytic regeneration efficiency (91.7 %) after 7 rounds of degradation cycles in the natural water matrix. Experimental results and theoretical analysis collaboratively showed that the porous 3D extended structure with expanded interlayer spacing promoted the mass transfer and adsorption of OMPs. Furthermore, the Ti-ON bonds acting as electron transport bridges could promote the generation of photogenerated electrons from CTF and directional movement of them to TiO2 for efficient utilization. These findings reinforce the understanding of the adsorption-promoted 3D structure and site-specific regulation of directed electron-feeding, providing a feasible and convenient solution for the removal of OMPs in water.

Focus on software, data acquisition, and instrumentation

Focus on software, data acquisition, and instrumentation