Distribution Of Functional Groups Research Articles

Liquid-Phase NMR of Humic and Fulvic Acids.

Present review focuses on the most recent advances in the NMR of the coal-derived humic and fulvic acids, covering exclusively the results of the liquid-phase NMR and leaving apart an overwhelming amount of publications dealing with the solid-state NMR investigations in this field (the latter are comprehensively reviewed elsewhere). Owing to the complexity of humic and fulvic acids together with other coal-derived products, their 1H and 13C NMR spectra consist of a number of overlapping signals belonging to different hydrocarbon types. Comprehensive studies of humic and fulvic acids by means of NMR revealed characteristic functional groups of their composition together with spectral regions in which they resonate. Quantitative 1H and 13C NMR spectra characterize aromatic and saturated carbons spread over many structural moieties, which provides a solid guideline into molecular structure of humic and fulvic acids together with parent coal-derived products. Nowadays, quantitative 13C NMR measurements yield information about a variety of structural parameters such as functional group distribution, aromaticity, degree of condensation of aromatic rings, and medium chain lengths together with many other more specific parameters. The structural NMR studies of the coal-derived products are developing on a background of a marked progress in experimental and computational NMR. Discussed in the present review are the most recent advances in the liquid-state NMR studies of the coal-derived humic and fulvic acids together with their processing products.

Nanoscale Janus particle fabrication and direct observation by super-resolution microscopy

We have developed a new and facile approach for synthesis, labeling, and characterizing amphiphilic nanoscale Janus particles. The aqueous dispersion of the Aerodisp W1226 fumed silica particles were embedded into polycarbonate (P.C.) microspheres surfaces via inverse solvent displacement method and further primary functionalization by an amine group. Subsequently, the polymer was dissolved, and a second modification was preferred to introduce a thiol group on the revealed embedded side of the particles, forming silica-based Janus/amphiphilic particles. We first characterized the Janus particles by laser scanning confocal microscopy and then with direct stochastic optical reconstruction microscopy (dSTORM) to detect the labeling distribution of the different functional groups. Super-resolution imaging results confirmed that the fabricated particles are Janus particles with different chemical properties on each hemisphere. The particles were also characterized by scanning and transmission electron microscopy for size and shape. The results showed aspherical particles with two hemispheres, confirming successful fabrication and chemical modification. Also, this work successfully demonstrated the synthesis, characterization and analysis of nanoscale Janus/amphiphilic particles nanoscale Janus particle.

Synthesis of basic amino acid-grafted lignin for use as a high-performance pigment dispersant

Lignin is a promising dispersant due to its hyperbranched polymer structure, low cost, renewability and abundant availability. However, its use is limited by its broad molecular weight distribution, inhomogeneity, and low content of hydrophilic functional groups. In this work, lignin was functionalized with alkaline amino acids (EHL-AA) to enhance water solubility and molecular weight uniformity. The results showed that EHL-AA significantly improved the dispersion of pigment Red 57:1 (P.R.57:1) in aqueous solutions, reducing the required dosage by 50 % compared to commercial small-molecule dispersants. Additionally, histidine modified lignin (EHL-His) exhibited superior stability for P.R.57:1 compared to commercial lignosulfonate (REAX 85A). Molecular dynamics simulations further revealed that showed that EHL-His had the highest electrostatic potential difference and the largest absolute value of negative ESP. The adsorption of EHL-His onto the P.R.57:1 surface followed the pseudo-second-order kinetic model and the Langmuir model, with EHL-His showing a higher Langmuir constant (b) than REAX 85A, indicating the strongest interaction with the pigment. In summary, this work advances pigment dispersion technology and promotes the high-value utilization of lignin.

Structural Evolution of Microgels During Precipitation Polymerization Revealed by Light Scattering and Electrophoresis

AbstractWhile precipitation polymerization allows the synthesis of microgels with controlled functional‐group distributions, the structural development of these microgels during the polymerization process still remains unclear. In this study, microgels with different reactivity ratios between the monomer and charged co‐monomer are prepared by precipitation polymerization, and the evolution of their size, thermoresponsive behavior, and surface properties during polymerization are evaluated. In particular, the surface properties of the microgels are analyzed quantitatively using the softness parameter and the surface charge density is calculated using Ohshima's equation. The results allowed describing the structural changes of microgels during precipitation polymerization well and provided design guidelines for functional microgels with controlled functional group distributions.

Radial Distribution of Functional Groups in Polyacrylonitrile Pre-oxidized Fibers

Radial Distribution of Functional Groups in Polyacrylonitrile Pre-oxidized Fibers

Point-Spread Function Deformations Unlock 3D Localization Microscopy on Spherical Nanoparticles.

Nanoparticles (NPs) have proven their applicability in biosensing, drug delivery, and photothermal therapy, but their performance depends critically on the distribution and number of functional groups on their surface. When studying surface functionalization using super-resolution microscopy, the NP modifies the fluorophore's point-spread function (PSF). This leads to systematic mislocalizations in conventional analyses employing Gaussian PSFs. Here, we address this shortcoming by deriving the analytical PSF model for a fluorophore near a spherical NP. Its calculation is four orders of magnitude faster than numerical approaches and thus feasible for direct use in localization algorithms. We fit this model to individual 2D images from DNA-PAINT experiments on DNA-coated gold NPs and demonstrate extraction of the 3D positions of functional groups with <5 nm precision, revealing inhomogeneous surface coverage. Our method is exact, fast, accessible, and poised to become the standard in super-resolution imaging of NPs for biosensing and drug delivery applications.

Using multi-modal spectroscopy technology and microscopic analysis to explore the regulation of ultra-high pressure heat-assisted treatment on the texture of ready-to-eat shrimp during storage

This study employed multi-modal spectroscopy technology and microscopic analysis to investigate the effects of various treatments on the texture of ready-to-eat (RTE) shrimps during storage. The results indicated that ultra-high pressure heat-assisted treatment (UHP-HAT) significantly improved the texture properties of RTE shrimps while simultaneously reducing the carbonyl and trichloroacetic acid-soluble properties associated with protein oxidative degradation. Furthermore, UHP-HAT resulted in a denser and more ordered protein structure, which contributed to an increased content of bound and immobile water. A partial least squares regression model for texture prediction was developed using data obtained from hyperspectral imaging, demonstrating a strong correlation between spectral information and texture parameters. Additionally, infrared imaging was utilized to elucidate the distribution of functional groups (OH, CO, CH) and carbonyl compounds within the proteins. Overall, the findings suggested that UHP-HAT could effectively delay the deterioration of texture by mitigating protein degradation.

Process Condition Optimization and Structural Feature Analysis of Humic Acid Extraction from Weathered Lignite.

In this study, response surface methodology (RSM) was adopted to investigate the optimization of process conditions for extracting humic acid (HA) from coal, aiming to enhance the yield of humic acid. Additionally, UV-vis spectroscopy, FTIR, XRD, TG-DTG, CP/MAS13CNMR, XPS, and molecular fluorescence were utilized to examine the properties of HAs. The extraction time significantly influenced the yield from Lishi weathered lignite, while the liquid-solid ratio had a significant impact on the yield from Wuhai weathered lignite. The interactive effect between factors did not have a significant effect on the yield. The optimal extraction conditions for Lishi humic acid (LSHA) were determined to be an extraction time of 4.4 h, NaOH concentration of 0.30 mol/L, and liquid-solid ratio of 21 mL/g, while those for Wuhai humic acid (WHHA) were 3.1 h, 0.21 mol/L, and 12 mL/g, respectively. Under these optimal conditions, the true yield values closely matched the predicted value obtained from the model optimization. Comparative analysis of the HAs revealed similarities in their chemical properties, including the degree of aromaticity, molecular weight, and distribution of functional groups. The aromaticity of WHHA was higher compared to that of LSHA. The higher hydrophilic-hydrophobic index of LSHA contributed to its relatively high biological activity compared to that of WHHA. Both humic acids belong to terrestrial humic acids. The results of the study provide a reference for further application of humic acid.

Observation of tapered multicore fibers based on Nb2CTx for humidity sensing: Experiment and DFT simulation investigations

Recent advancements in the area of human healthcare monitoring and medical diagnosis have sparked a revived interest in humidity sensors. Nb2CTx, characterized by its multilayered structure, large specific surface area, and plentiful hydrophilic groups, actively absorbs a sufficient quantity of water molecules. In this work, the sensing capability and mechanism of water molecules are investigated under different proportions of functional group distribution on the surface of Nb2CTx MXene employing plane-wave based density functional theory calculations, and the provided models can offer guiding principles for the experimental preparation of the highly sensitive humidity sensor based on Nb2CTx. To verify the effectiveness of the model, Nb2CTx material is coated on a Tapered Three-Core Fiber (TTCF), and the high evanescent field characteristics of the sensor are utilized to further improve its performance. As the relative humidity (RH) increased from 35 % to 75 %, the transmitted spectra exhibited a redshift with a sensitivity of 22pm/% RH. Within the relative humidity range of 75 % to 95 %, the Nb2CTx coating heightened water molecule absorption, resulting in a more pronounced redshift in the transmitted spectra. This phase manifests a maximum humidity sensitivity of 299pm/% RH. Noteworthy advantages of this sensor include its uncomplicated structure, cost-effectiveness, and robust stability, rendering it highly suitable a wide variety of potential applications in fields such as biology, chemical and health processing.

Improving the performance of glucose oxidase biofuel cell by methyl red and chitosan composite electrodes

This research aims to improve the output power of self-pumping glucose enzymatic biofuel cell (EBFC) and modifying the anode. Adding a fixed ratio of methyl red-chitosan (MR-CS) can effectively improve the EBFC efficiency and stability. In addition, chitosan can be obtained from discarded crustacean fishery waste objects such as shrimp and oysters, are also significant to the use of environmentally friendly materials. The catalyst was immobilized on pyrenecarboxaldehyde (PCA), polyethyleneimine (PEI) and multi-wall carbon nanotubes (MWCNT) and combined with glucose oxidase (GOx). Finally, the [PCA/GOx]/PEI/Nafion solution/MWCNT/[MR-CS] catalyst was immobilized on the carbon cloth. Experimental analysis was progressed under the preparation of enzyme-supported electrode to observe the feasibility of the anode electrode. Experiment including Fourier transform infrared spectroscopy (FTIR) to analyze the distribution of functional groups after modification of the carbon cloth electrode, and through the comparison of the ultraviolet–visible spectrometer (UV–Vis), it can be known that the concentration ratio of [MR-CS] is 1:5, the glucose oxidase load can be maximized. Electrochemical analysis (Cyclic Voltammetry, CV) measures the activity of the maximum reaction of the anode material and the corresponding redox peak, and scanning electron microscope (SEM) observes the surface morphology of the modified electrode. Self-pumping glucose enzymatic biofuel cell module was assembled and examined, the results showed that the maximum output power density (MPD) was 2.64 mW/cm2.

Spatial phytoplankton community structure revealed by photosynthetic pigments in the tropical estuarine-coastal zone (Bangladesh)

To explore the variation of phytoplankton community along the Bakkhali river estuary and its adjacent coastal water in the north of the Bay of Bengal, total Chl-a (TChl-a) concentrations and group-specific photosynthetic pigments were investigated during April 2017. Distinct spatial distribution was observed in temperature, turbidity and nutrient concentrations as well as in TChl-a concentrations, showing a seaward decreasing pattern. The different distribution of phytoplankton pigments and functional groups along the gradients was also observed. Chlorophyll-b and zeaxanthin showed their highest abundance in the turbid riverine water, while alloxanthin and prasinoxanthin dominated in the coastal water. High concentrations of fucoxanthin, peridinin and hex-fucoxanthin were associated with high-light availability and showed a seaward increasing trend. Three phytoplankton groups can be classified: the riverine group (chlorophytes and cyanobacteria), the coastal group (cryptophytes and prasinophytes) and the offshore group (diatoms, dinoflagellate and haptophytes_type 6). The predominance of cryptophytes (avg. 48%) over diatoms (avg. 28%) was basically influenced by the scarcity of nitrogen and silicate relative to phosphate. Not only availability of nutrients, the photosynthetically active radiation also plays a key role in regulating TChl-a, photosynthetic pigments and functional groups in this tropical estuarine-coastal zone.

Environmental factors affecting the spatio-temporal distribution of zooplankton functional groups in a deep alkaline lake

Environmental factors affecting the spatio-temporal distribution of zooplankton functional groups in a deep alkaline lake

Revealing the Molecular Interaction between CTL Base Oil and Additives and Its Application in the Development of Gasoline Engine Oil

In order to improve fuel economy to meet the standard for passenger car oil, a new formulation with good viscosity–temperature performance for gasoline engine oil is required. In this study, coal-to-liquid (CTL) base oil, with a high viscosity index and good low-temperature performance, was selected as the base oil to develop the gasoline engine oil. A systematic study on the molecular interaction between the CTL base oil and the viscosity index improver (VII), including three kinds of hydrogenated styrene diene copolymers (HSD-type) and four kinds of ethylene propylene copolymers (OCP-type), was conducted. It was found that in general, in CTL base oil, the HSD-type VII exhibited a much higher viscosity index, a significantly lower shear stability index, a higher thickening ability, and a lower cold-cranking simulator (CCS) viscosity than that of OCP-type VII. Moreover, when comparing CTL base oil with mineral oil 150N, the combination of CTL base oil and the VII displayed a lower CCS viscosity than that of mineral oil, suggesting it had better low-temperature performance and was able to quickly form a protective oil film on the surface, which was beneficial for the cold start. The functional group distribution state of the VII in base oil was analyzed using synchrotron radiation micro-infrared microscope (SR Micro-IR) technology, which revealed that HSD-1 had a better molecular interaction with CTL6 than 150N because of the better uniformity of the C=C group distribution. Based on this, a SP 0W-20 gasoline engine oil was developed by the combination of CTL base oil and the HSD-1 viscosity index improver, together with an additive package, a polymethacrylate pour point depressant, and a non-silicone defoamer, which showed excellent low-temperature performance, thermal oxidation stability, and detergency performance compared to the reference oil.

Recent advances in liquid-phase NMR of the coal-derived products.

Present review focuses on the most recent advances in a liquid-phase nuclear magnetic resonance (NMR) of the coal-derived products-coal tar pitches, asphaltenes, and humic and fulvic acids, covering exclusively the results in the liquid-phase NMR studies leaving apart an overwhelming amount of publications dealing with the solid-state NMR investigations in this field (which are comprehensively reviewed elsewhere). Owing to the complexity of the coal-derived products, their 1H and 13C NMR spectra consist of a number of overlapping signals belonging to different hydrocarbon types. Comprehensive studies of coal tar pitches, asphaltenes, and humic and fulvic acids by means of NMR over the past several decades revealed characteristic functional groups of those fractions together with spectral regions in which they resonate. Quantitative 1H and 13C NMR spectra characterize aromatic and saturated carbons spread over many structural moieties, which provides a solid guideline into molecular structure of the coal-derived products. Nowadays, quantitative 13C NMR measurements yield information about a variety of structural parameters such as functional group distribution, aromaticity, degree of condensation of aromatic rings, and medium chain lengths together with many other more specific parameters. The structural NMR studies of coal and coal-derived products are developing on a backdrop of a marked progress in computational NMR. At present, we are witnessing an unprecedentedly fast development of theoretical and computational methods in the field of NMR spectroscopy. Discussed in the present review are the most recent advances in the NMR studies of the processing products of peat, lignite or brown coal, anthracite or hard coal, and graphite in solution, like coal tar pitches, asphaltenes, and humic and fulvic acids.

Theoretical and Experimental Insights into the Spatial Distribution of Functional Groups in a Multivariate Flexible Metal–Organic Framework

Theoretical and Experimental Insights into the Spatial Distribution of Functional Groups in a Multivariate Flexible Metal–Organic Framework

Deciphering functional groups of rumen microbiome and their underlying potentially causal relationships in shaping host traits.

Over the years, microbiome research has achieved tremendous advancements driven by culture-independent meta-omics approaches. Despite extensive research, our understanding of the functional roles and causal effects of the microbiome on phenotypes remains limited. In this study, we focused on the rumen metaproteome, combining it with metatranscriptome and metabolome data to accurately identify the active functional distributions of rumen microorganisms and specific functional groups that influence feed efficiency. By integrating host genetics data, we established the potentially causal relationships between microbes-proteins/metabolites-phenotype, and identified specific patterns in which functional groups of rumen microorganisms influence host feed efficiency. We found a causal link between Selenomonas bovis and rumen carbohydrate metabolism, potentially mediated by bacterial chemotaxis and a two-component regulatory system, impacting feed utilization efficiency of dairy cows. Our study on the nutrient utilization functional groups in the rumen of high-feed-efficiency dairy cows, along with the identification of key microbiota functional proteins and their potentially causal relationships, will help move from correlation to causation in rumen microbiome research. This will ultimately enable precise regulation of the rumen microbiota for optimized ruminant production.

Alkali induced changes in spatial distribution of functional groups in carboxymethylated cellulose – comparison of cotton and viscose fibers

The aim of the work was to compare the levels of carboxymethylation on cotton with what was obtained previously on viscose fibers under the same treatment conditions. In addition to carboxymethylation levels, their performance was also compared in terms of their propensity for sorption of methylene blue, a cationic dye that is a putative wastewater contaminant. Under comparable conditions of treatment, the degree of carboxymethylation in cotton was 30–90% of that in viscose but the molar ratio of dye sorption to carboxyl groups was 100–230% of that in viscose. In other words, as compared to cotton, viscose fibers showed higher degrees of carboxymethylation but lower accessibility of the carboxyl groups to dye molecules. The divergence between the fiber types is attributed to differences in the spatial distribution of substituted carboxymethyl groups within their structures, as well as the inherently greater swelling propensity of the viscose as compared to cotton. Further work is under way to determine if the order of performance as measured through dye sorption (cotton better than viscose) will also hold true if the performance metric is changed to water and moisture sorption.

Effects of reduced tillage and prolonged cover cropping in maize on soil quality and yield

Maize (Zea mays L.) is the most common arable crop on sandy soils in the Netherlands, and it is often grown for several consecutive years after temporary grassland. For the maize-growing years, reduced tillage intensity and prolonged growing period of cover crops could limit declines in soil organic matter (SOM) and soil biota while maintaining soil structure and maize yield. We measured soil parameters and maize yield in an eight-years field experiment on sandy Gleyic Podzol. Treatments included four cropping systems differing in tillage intensity but with conventional sowing dates (conventional inversion tillage (CT), non-inversion tillage (NIT), strip tillage (ST) and no-till (NT)), and two cropping systems (CT-prolonged and ST-prolonged) with prolonged growing period of a winter rye-winter pea cover crop combined with a late sown short-season maize (18 weeks growth). After eight years, we found no evidence for differences in SOM or total carbon content between the treatments. However, in the reduced-tillage treatments, SOM content was higher in the top (0–15 cm) than in the bottom (15–30 cm) of the plough layer, while in CT and CT-prolonged, this stratification was inverted. We observed differences in earthworm abundance, biomass and functional group distribution. In comparison to CT (100 %), the earthworm abundance was 153 % in NIT, 235 % in ST and 206 % in NT whereas earthworm biomass was 269 % in NIT, 325 % in ST and 475 % in NT. Epigeic earthworms were more affected by tillage than endogeic earthworms. Compared to CT, earthworm biomass was higher in CT-prolonged. The initially low earthworm population recovered during the course of the experiment independent of tillage intensity.Higher soil penetration resistance was observed in the reduced tillage systems compared to CT, independent of prolonging the cover crop. Despite the increased penetration resistance, the maize yields in NIT and ST were similar to CT. The maize yields were lower in NT, CT-prolonged and ST-prolonged compared to CT, but no differences were observed between CT-prolonged and ST-prolonged. The biomass of the harvested prolonged cover crop closed the yield gap in relation to CT in four out of six years in which cover crop biomass in CT-prolonged and ST-prolonged was quantified. Based on our results, we recommend strip tillage for continuous maize-cropping systems on Dutch sandy soils. In the case of severe compacting of compaction prone soils, we recommend conventional tillage with a prolonged cover crop and short-season maize variety.

Nanoscale Surface and Bulk Electronic Properties of Ti3C2Tx MXene Unraveled by Multimodal X-Ray Spectromicroscopy.

2D layered materials, such as transition metal carbides or nitrides, known as MXenes, offer an ideal platform to investigate charge transfer processes in confined environment, relevant for energy conversion and storage applications. Their rich surface chemistry plays an essential role in the pseudocapacitive behavior of MXenes. However, the local distribution of surface functional groups over single flakes and within few- or multilayered flakes remains unclear. In this work, scanning X-ray microscopy (SXM) is introduced with simultaneous transmission and electron yield detection, enabling multimodal nanoscale chemical imaging with bulk and surface sensitivity, respectively, of individual MXene flakes. The Ti chemical bonding environment is found to significantly vary between few-layered hydrofluoric acid-etched Ti3C2Tx MXenes and multilayered molten salt (MS)-etched Ti3C2Tx MXenes. Postmortem analysis of MS-etched Ti3C2Tx electrodes cycled in a Li-ion battery further illustrates that simultaneous bulk and surface chemical imaging using SXM offers a method well adapted to the characterization of the electrode-electrolyte interactions at the nanoscale.

Kinetics of pyrolysis and Computational Fluid Dynamics modeling of low metamorphic coal

AbstractThis study explores the low‐temperature pyrolysis kinetic of low metamorphic grade coal from Northern Shaanxi, utilizing Fourier transform infrared (FT‐IR) spectroscopy to analyze the characteristics of various functional groups over a 293–1023 K temperature range. A kinetic model, correlating with the pyrolysis behaviors of these groups, was developed through thermal analysis kinetics. Computational fluid dynamics (CFD) technology simulated the furnace's flow dynamics, allowing an examination of the physical field alterations and functional group evolution during pyrolysis. Results showed that the pyrolysis kinetic functions for aromatic C–H, C=C, C–O, and •OH, along with temperature, pressure, and velocity fields, were successfully integrated into the simulation. This integration provided detailed insights into the temperature profile, pressure distribution, flow velocities, and functional group distribution in the furnace. Aliphatics, exhibiting the largest mass fraction and wide pyrolysis temperature range, and •OH radicals with the highest activation energy were concentrated in the furnace's pyrolysis zone center. C=C's distribution was influenced by aromatic C–H and aliphatics, showing a complementary pattern. The oxygen‐containing groups C–O and C=O had similar pyrolysis mechanisms and uniform distribution. The functional groups' mass fractions were ranked from highest to lowest as follows: aliphatics &gt; •OH &gt; aromatic C–H &gt; C–O &gt; C=C &gt; C=O.