Fine Structural Features Research Articles

Progress and challenges in structural, in situ and operando characterization of single-atom catalysts by X-ray based synchrotron radiation techniques.

Single-atom catalysts (SACs) represent the ultimate size limit of nanoscale catalysts, combining the advantages of homogeneous and heterogeneous catalysts. SACs have isolated single-atom active sites that exhibit high atomic utilization efficiency, unique catalytic activity, and selectivity. Over the past few decades, synchrotron radiation techniques have played a crucial role in studying single-atom catalysis by identifying catalyst structures and enabling the understanding of reaction mechanisms. The profound comprehension of spectroscopic techniques and characteristics pertaining to SACs is important for exploring their catalytic activity origins and devising high-performance and stable SACs for industrial applications. In this review, we provide a comprehensive overview of the recent advances in X-ray based synchrotron radiation techniques for structural characterization and in situ/operando observation of SACs under reaction conditions. We emphasize the correlation between spectral fine features and structural characteristics of SACs, along with their analytical limitations. The development of IMST with spatial and temporal resolution is also discussed along with their significance in revealing the structural characteristics and reaction mechanisms of SACs. Additionally, this review explores the study of active center states using spectral fine characteristics combined with theoretical simulations, as well as spectroscopic analysis strategies utilizing machine learning methods to address challenges posed by atomic distribution inhomogeneity in SACs while envisaging potential applications integrating artificial intelligence seamlessly with experiments for real-time monitoring of single-atom catalytic processes.

MOF-based photothermal Janus membrane with robust anti-fouling performance for enhanced membrane distillation

As a promising desalination technology, photothermal membrane distillation (PMD) is confronted with challenges such as low freshwater yield and membrane fouling. Herein, we have introduced a copper-based metal-organic framework (Cu-CAT) into a hydrophilic/superhydrophobic polyvinylidene fluoride (PVDF) Janus tree-like nanofiber membrane (TLNMs) to construct photothermal Janus TLNMs (P-Janus TLNMs) for enhanced PMD. Given the exceptional photothermal properties of the hydrophilic Cu-CAT layer, coupled with the fine pore structure and elevated porosity characteristics of the superhydrophobic PVDF TLNMs, P-Janus TLNMs have demonstrated outstanding performance when integrated into a PMD system. Upon exposure to solar illumination of 1 kW·m−2, the P-Janus TLNMs achieved a remarkable surface temperature of 88 °C, yielding a permeation flux of 1.46 L m−2 h−1, a salt rejection rate exceeding 99.99 %, and an energy utilization rate of 81 %. Furthermore, after 20 days of continuous operation with simulated seawater containing oil and surfactant, the P-Janus TLNMs presented a salt rejection of 99.9 % and a stable permeation flux of 1.71 L m−2 h−1 at the feed/permeate temperatures of 24/20 °C. This work introduces a novel membrane with immense potential for boosting permeation flux and enhancing anti-fouling properties in PMD, thereby advancing the frontier of sustainable seawater desalination.

Architecture of the flagellar apparatus and related structures in Kolkwitziella acuta: Towards a fine-structural characterization of pallium-feeding dinoflagellates (Protoperidiniaceae)

The fine-structural organization of the protoperidiniacean Kolkwitziella acuta was examined by SEM and TEM. Serial sections of five cells of K. acuta were used to study the architecture of basal bodies and associated roots, the pusular system, and the feeding apparatus. The basal bodies were inserted 1 µm apart at an angle of ca. 80°, and displayed the typical peridinioid features of associating with two roots each and having a layered connective linking the longitudinal microtubular root to the transverse striated root. The transverse flagellar canal was associated with a ‘sac pusule’, while the longitudinal flagellar canal was linked, via a pusule canal surrounded by a conspicuous layer of striated material, to a collecting chamber from which ca. 40 pusular tubes radiated. An extruded pallium was present, associated with a microtubular strand (the MSP) that extended anteriorly and progressively separated into six or seven groups of microtubules, with electron-opaque vesicles present along the MSP. A prominent striated collar surrounded the exit area of the pallium and was connected to the striated collars of both the transverse and longitudinal flagellar canals. The partial nuclear-encoded LSU rDNA sequence confirmed the identification as K. acuta. The currently known fine-structural features of pallium-feeding Protoperidiniaceae are summarized.

Starch-related structural basis and enzymatic mechanism of the different appearances of soft rice

To investigate the fine starch structure characteristics and formation mechanism of high-quality appearance soft rice, two high-quality and low-quality soft rice varieties (HA-SR and LA-SR, respectively) were selected. Differences in appearance quality, fine starch structure, and activity of key enzymes involved in starch synthesis during the grain-filling stage were compared. The results showed that compared with LA-SR, HA-SR were less chalky, more transparent, had larger starch grains, a lower content of shorter chains (DP 6–24), a higher content of longer chains (DP ≥ 25), lower relative crystallinity, fewer ordered structures, more amorphous structures and larger thicknesses of semi-crystalline lamellae. In terms of amylase activity during the grain-filling stage, the AGPase and GBSS activities of HA-SR were higher, and the SBE activity of HA-SR was lower compared to LA-SR. In conclusion, higher AGPase activity can produce a higher filling rate resulting in fuller starch grain in soft rice. Fuller starch grains reduce the chalkiness of soft rice. Higher AGPase and GBSS activities and lower SBE activity can result in soft rice with more long-branched and less short-branched amylopectin. Thus, soft rice has lower relative crystallinity and less ordered structure. These structures may facilitate reduce grain chalkiness and improve grain transparency.

High-strength aluminum alloy processed by micro laser powder bed fusion (μ-LPBF): Coordination of laser formability, microstructure evolution, and mechanical properties

As the scale of additive manufacturing process (e.g., laser spot size, powder particle size, powder layer thickness) decreases, the application of micro laser powder bed fusion (μ-LPBF) involves novel mechanisms for process, microstructure and performance coordination. This study provides a systematic view of the processing window and performance enhancement of high-strength Al-Mg-Sc-Zr alloy fabricated by μ-LPBF. The effects of μ-LPBF parameters on defect control and densification activity of the printed parts were analyzed, so as to obtain the suitable processing window. The influence of building orientation and heat treatment on microstructural characteristics and mechanical properties of μ-LPBF processed parts was studied. The μ-LPBF Al-Mg-Sc-Zr exhibited sound surface quality (Ra of 6.088 μm) and considerably refined grains with an average size of 1.102 μm, which was related to the high cooling rate (8.6 × 107 K/s) induced by a small-sized laser beam (25 μm) and a tiny powder particle size distribution (2–20 μm) applied in μ-LPBF. After aging treatment (325 °C/4 h), the superior ultimate tensile strength of 590.24 ± 4.75 MPa combined with the sufficiently high elongation of 11.99 ± 1.17 % was achieved. Due to the significantly decreased scale of μ-LPBF production, the anisotropy caused by the variation of building directions was negligible. These enhanced mechanical properties were attributed to the combined effect of the grain size refinement, the higher number density (1.2 × 1024/mm3) of interior precipitates within grains, and the small-sized molten pool size of μ-LPBF. Computational fluid dynamics (CFD) simulation was applied to reveal the molten pool thermodynamics, indicating that a higher thermal temperature gradient (up to 9.8×107 K/m), a smaller molten pool size (with the width of 38.7–69.8 μm and depth of 8.7–30.0 μm) were generated in μ-LPBF. This work presents great potential in processing high-precision metallic components with fine structural feature size and satisfactory manufacturing quality.

Boundary-Aware Gradient Operator Network for Medical Image Segmentation.

Medical image segmentation is a crucial task in computer-aided diagnosis. Although convolutional neural networks (CNNs) have made significant progress in the field of medical image segmentation, the convolution kernels of CNNs are optimized from random initialization without explicitly encoding gradient information, leading to a lack of specificity for certain features, such as blurred boundary features. Furthermore, the frequently applied down-sampling operation also loses the fine structural features in shallow layers. Therefore, we propose a boundary-aware gradient operator network (BG-Net) for medical image segmentation, in which the gradient convolution (GConv) and the boundary-aware mechanism (BAM) modules are developed to simulate image boundary features and the remote dependencies between channels. The GConv module transforms the gradient operator into a convolutional operation that can extract gradient features; it attempts to extract more features such as images boundaries and textures, thereby fully utilizing limited input to capture more features representing boundaries. In addition, the BAM can increase the amount of global contextual information while suppressing invalid information by focusing on feature dependencies and the weight ratios between channels. Thus, the boundary perception ability of BG-Net is improved. Finally, we use a multi-modal fusion mechanism to effectively fuse lightweight gradient convolution and U-shaped branch features into a multilevel feature, enabling global dependencies and low-level spatial details to be effectively captured in a shallower manner. We conduct extensive experiments on eight datasets that broadly cover medical images to evaluate the effectiveness of the proposed BG-Net. The experimental results demonstrate that BG-Net outperforms the state-of-the-art methods, particularly those focused on boundary segmentation.

An offset-transformer hierarchical model for point cloud-based resistance spot welding quality classification

Resistance spot welding (RSW) is a widely used welding technology in automotive manufacturing, and weld nugget quality is closely related to the quality of the vehicle body. Offline random checks are largely relied on the quality inspection of weld nuggets, but they have low efficiency and high cost. To address this issue, this paper proposes a deep learning model for RSW weld nugget classification, named the offset-transformer hierarchical model (OFTFHC), which is based on the point cloud data of its appearance shape. OFTFHC uses a hierarchical network structure to gradually expand the receptive field. A local feature module is introduced to extract local features from the point cloud, effectively enabling the recognition of the fine structural features of the resistance spot weld point cloud. A residual ratio module, which is based on MLP_MA and uses max and average functions for feature enhancement, is designed to adapt to the complex spatial structure of the point cloud. The offset-transformer structure is used to learn global context features, thereby enhancing the global feature extraction capability. Through classification experiments on RSW weld nuggets across 5 categories with a total of 1050 samples, OFTFHC achieved an average accuracy of 80.6 %, outperforming existing models. This demonstrates the effectiveness and superiority of the method, making it highly suitable for weld nugget quality control in automotive automation production lines.

An insight into the cryptic diversity of Fragilariaceae (Bacillariophyta), with the description of a new Antarctic species, Gedaniella antarctica sp. nov.

ABSTRACT Fragilariaceae is a paraphyletic family of araphid diatoms commonly used as bio-indicators, in environmental assessments and in paleoenvironmental reconstructions, and with various potential industrial applications. Recent molecular taxonomic research has highlighted significant limitations in traditional morphology-based investigations of these diatom species. Most descriptions of species and genera of the Fragilariaceae present broad morphological character definitions and many diagnostic characters are indistinguishable by light microscopy. In this sense, taxon misidentification is common and could have serious implications for environmental surveys and laboratory experiments. To better understand the diversity of the Fragilariaceae, we (1) performed phylogenetic analyses of the small subunit ribosomal RNA (18S rRNA), rbcL and psbC gene sequences, (2) inferred a cladogram from key morphological features used in the traditional identification of Fragilariaceae, (3) tested if the topologies of the tree recovered from the molecular phylogeny, of the tree based on morphology and of the trees constraining to monophyly the genera Sarcophagodes, Pseudostaurosira and Nanofrustulum (together and separately) were significantly different and (4) mapped morphological character states on the ML tree and inferred their evolution based on maximum parsimony. Our results supported the monophyly of a group of Fragilariaceae within small araphid diatoms including the genera Cratericulifera, Plagiostriata, Castoridens, Opephora, Staurosira, Staurosirella, Punctastriata, Psammotaenia, Hendeyella, Stauroforma, Pseudostaurosira sensu Li, Nanofrustulum sensu Li, Serratifera sensu Li and Gedaniella sensu Li. Molecular phylogeny and topology tests suggested that the latest circumscriptions of the genera Sarcophagodes, Pseudostaurosira and Nanofrustulum sensu Morales were not monophyletic. Analyses of the Antarctic strain IMA070A collected during the XXXIV Italian Antarctic Expedition using fine structural features of the frustule and molecular data revealed that this diatom belongs to a distinct lineage within Gedaniella, which we describe here as Gedaniella antarctica sp. nov.

Extended X-ray absorption spectroscopy using an ultrashort pulse laboratory-scale laser-plasma accelerator

Laser-driven compact particle accelerators can provide ultrashort pulses of broadband X-rays, well suited for undertaking X-ray absorption spectroscopy measurements on a femtosecond timescale. Here the Extended X-ray Absorption Fine Structure (EXAFS) features of the K-edge of a copper sample have been observed over a 250 eV window in a single shot using a laser wakefield accelerator, providing information on both the electronic and ionic structure simultaneously. This capability will allow the investigation of ultrafast processes, and in particular, probing high-energy-density matter and physics far-from-equilibrium where the sample refresh rate is slow and shot number is limited. For example, states that replicate the tremendous pressures and temperatures of planetary bodies or the conditions inside nuclear fusion reactions. Using high-power lasers to pump these samples also has the advantage of being inherently synchronised to the laser-driven X-ray probe. A perspective on the additional strengths of a laboratory-based ultrafast X-ray absorption source is presented.

Ultraclean Suspended Graphene by Radiolysis of Adsorbed Water.

Access to intrinsic properties of a 2D material is challenging due to the absence of a bulk that would dominate over surface contamination, and this lack of bulk also precludes effective conventional cleaning methods that are almost always sacrificial. Suspended graphene and carbon contaminants represent the most salient challenge. This work has achieved ultraclean graphene, attested by electron energy loss (EEL) spectra unprecedentedly exhibiting fine-structure features expected from bonding and band structure. In the cleaning process in a transmission electron microscope, radicals generated by radiolysis of intentionally adsorbed water remove organic contaminants, which would otherwise be feedstock of the notorious electron irradiation induced carbon deposition. This method can be readily adapted to other experimental settings and other materials to enable previously inhibited undertakings that rely on the intrinsic properties or ultimate thinness of 2D materials. Importantly, the method is surprisingly simple and robust, easily implementable with common lab equipment.

Using molecular fine structure to identify optimal methods of extracting fungal glycogen

Glycogen is a highly branched glucose polymer that is an energy storage material in fungi and animals. Extraction of glycogen from its source in a way that minimizes its molecular degradation is essential to investigate its native structure. In this study, the following extraction methods were compared: sucrose gradient density ultracentrifugation, thermal alkali, hot alcohol and hot water extractions. Molecular-size and chain-length distributions of glycogen were measured by size-exclusion chromatography and fluorophore-assisted carbohydrate electrophoresis, respectively. These two fine-structure features are the most likely structural characteristics to be degraded during extraction. The results show that the thermal alkali, hot alcohol and hot water extractions degrade glycogen molecular size and/or chain-length distributions, and that sucrose gradient density ultracentrifugation with neither high temperature nor alkaline treatment is the most suitable method for fungal glycogen extraction.

Structural elucidation and functional characteristics of novel potential prebiotics produced from Limosilactobacillus reuteri N1 GtfB-treated maize starches

The recently characterized Limosilactobacillus reuteri N1 GtfB (LrN1 GtfB) from glycoside hydrolase family 70 is a novel 4,6-α-glucanotransferase acting on starch/maltooligosaccharides with high enzyme activity and soluble protein yield (in heterogenous system). In this study, the influence of the treatment by LrN1 GtfB on the fine structure and functional characteristics of three maize starches were furtherly investigated and elucidated. Due to the treatment of LrN1 GtfB, the starch molecules were transformed into reuterans containing linear and branched (α1 → 6) linkages with notably smaller molecular weight and shorter chain length. Moreover, the (α1 → 6) linkage ratios in the GtfB-modified high-amylose maize starch (GHMS)/normal maize starch (GNMS)/waxy maize starch (GWMS) increased by 18.3 %/12.6 %/9.0 % as compared to their corresponding controls. In vitro digestibility experiment revealed that the resistant starch content of GHMS, GNMS and GWMS increased by 16 %, 18 % and 25 % as compared to the starch substrates. Furthermore, the butyric acid yielded from GHMS, GNMS and GWMS in the in vitro fermentation experiments were 1.4, 1.5 and 1.4 times higher than those of commercial galactose oligosaccharides. These results indicated that the highly-branched short-clustered reuteran synthesized by LrN1 GtfB might serve as novel potential prebiotics, and provide insights for the synthesis of promising prebiotic dietary fiber from starch.

When simplicity triumphs: niche specialization of gut bacteria exists even for simple fiber structures.

Structurally complex corn bran arabinoxylan (CAX) was used as a model glycan to investigate gut bacteria growth and competition on different AX-based fine structures. Nine hydrolyzate segments of the CAX polymer varying in chemical structure (sugars and linkages), CAX, five less complex non-corn arabinoxylans, and xylose and glucose were ranked from structurally complex to simple. The substrate panel promoted different overall growth and rates of growth of eight Bacteroides xylan-degrading strains. For example, Bacteroides cellulosilyticus DSM 14838 (Bacteroides cellulosilyticus) grew well on an array of complex and simple structures, while Bacteroides ovatus 3-1-23 grew well only on the simple structures. In a competition experiment, B. cellulosilyticus growth was favored over B. ovatus on the complex AX-based structure. On the other hand, on the simple structure, B. ovatus strongly outcompeted B. cellulosilyticus, which was eliminated from the competitive environment by Day 11. This adaptation to fine structure and resulting competition dynamics indicate that dietary fiber chemical structures, whether complex or simple, favor certain gut bacteria. Overall, this work supports a concept that fiber degraders diversify their competitive abilities to access substrates across the spectrum of heterogeneity of fine structural features of dietary fibers.

Effect of the tip speed ratio on the wake characteristics of wind turbines using LBM‐LES

AbstractIn this paper, the wake characteristics of Zell 2000 wind turbine under different tip velocity ratios are studied by using the lattice Boltzmann method and large eddy simulation. The adaptive mesh refinement method is performed to capture the fine flow structure and wake characteristics development. In this paper, we mainly focus on the effect of the tip speed ratio on the flow structure and unsteady characteristics of wind turbine wake. The three‐dimensional flow vorticity structures, the section vorticity diagram, the pressure fluctuation of wake and the lift coefficient of wind turbine wake are utilized to explore the effect of the tip speed ratio on the unsteady physics mechanism of wind turbine wake. With the increase of the tip speed ratio, the distance between two adjacent vortex rings along the axial direction gradually decreases, as the position of the broken vortex circles gradually approaches the center of the blade, separated vortexes are rapidly generated, and the coherent structure appears closer to the wind turbine. A relationship is established between the tip speed ratios and the positions of the broken vortex circles. It is further found that the dominant frequency amplitude gradually increases with the increase of tip speed ratio and the pressure amplitude spectra of vortex increases with the decrease of the distance between the wake and the center of the blade axis. The above series of studies can provide significant physical insight into deep understanding the influence of the tip speed ratio on the wake characteristics of wind turbines.

Specific FRET Probes Sensitive to Chitosan-Based Polymeric Micelles Formation, Drug-Loading, and Fine Structural Features.

Förster resonance energy transfer (FRET) probes are a promising tool for studying numerous biochemical processes. In this paper, we show the application of the FRET phenomenon to observe the micelle formation from surfactants, micelles self-assembling from chitosan grafted with fatty acid (oleic-OA, or lipoic-LA), cross-linking of SH groups in the micelle's core, and inclusion and release of the model drug cargo from the micelles. Using the carbodiimide approach, amphiphilic chitosan-based polymers with (1) SH groups, (2) crosslinked with S-S between polymer chains, and (3) without SH and S-S groups were synthesized, followed by characterization by FTIR and NMR spectroscopy. Two pairs of fluorophores were investigated: 4-methylumbelliferon-trimethylammoniocinnamate-rhodamine (MUTMAC-R6G) and fluorescein isothiocyanate-rhodamine (FITC-R6G). While FITC-R6G has been described before as an FRET-producing pair, for MUTMAC-R6G, this has not been described. R6G, in addition to being an acceptor fluorophore, also serves as a model cytostatic drug in drug-release experiments. As one could expect, in aqueous solution, FRET effect was poor, but when exposed to the micelles, both MUTMAC-R6G and FITC-R6G yielded a pronounced FRET effect. Most likely, the formation of micelles is accompanied by the forced convergence of fluorophores in the hydrophobic micelle core by a donor-to-acceptor distance (r) significantly closer than in the aqueous buffer solution, which was reflected in the increase in the FRET efficiency (E). Therefore, r(E) could be used as analytical signal of the micelle formation, including critical micelle concentration (CMC) and critical pre-micelle concentration (CPMC), yielding values in good agreement with the literature for similar systems. We found that the r-function provides analytically valuable information about the nature and mechanism of micelle formation. S-S crosslinking between polymer chains makes the micelle more compact and stable in the normal physiological conditions, but loosens in the glutathione-rich tumor microenvironment, which is considered as an efficient approach in targeted drug delivery. Indeed, we found that R6G, as a model cytostatic agent, is released from micelles with initial rate of 5%/h in a normal tissue microenvironment, but in a tumor microenvironment model (10 mM glutathione), the release of R6G from S-S stitched polymeric micelles increased up to 24%/h. Drug-loading capacity differed substantially: from 75-80% for nonstitched polymeric micelles to ~90% for S-S stitched micelles. Therefore, appropriate FRET probes can provide comprehensive information about the micellar system, thus helping to fine-tune the drug delivery system.

Systematic Comparison of Atomistic Force Fields for the Mechanical Properties of Double-Stranded DNA.

The response of double-stranded DNA to external mechanical stress plays a central role in its interactions with the protein machinery in the cell. Modern atomistic force fields have been shown to provide highly accurate predictions for the fine structural features of the duplex. In contrast, and despite their pivotal function, less attention has been devoted to the accuracy of the prediction of the elastic parameters. Several reports have addressed the flexibility of double-stranded DNA via all-atom molecular dynamics, yet the collected information is insufficient to have a clear understanding of the relative performance of the various force fields. In this work, we fill this gap by performing a systematic study in which several systems, characterized by different sequence contexts, are simulated with the most popular force fields within the AMBER family, bcs1 and OL15, as well as with CHARMM36. Analysis of our results, together with their comparison with previous work focused on bsc0, allows us to unveil the differences in the predicted rigidity between the newest force fields and suggests a roadmap to test their performance against experiments. In the case of the stretch modulus, we reconcile these differences, showing that a single mapping between sequence-dependent conformation and elasticity via the crookedness parameter captures simultaneously the results of all force fields, supporting the key role of crookedness in the mechanical response of double-stranded DNA.

Large-eddy simulation of the effects of horizontal and vertical adjustments in a wind farm

In order to study the fine structural characteristics of the wind field and wind power generation in wind farms, large-eddy simulations (LES) with different layouts are carried out under a given wind direction. In the simulation, a single wind turbine can produce a wake effect, reducing the wind within 2 km by 50%, and the influence between wind turbines gradually decreases as the distance between the wind turbines increases. To minimize the impact of the wake effect between the turbines, the simulation considering horizontal and vertical staggering of the wind farm is conducted. Under the prevailing wind, the optimal power output for the entire wind farm is obtained when a horizontal staggering degree θ of 16.7 is used and no vertical staggering is adapted. Unexpectedly, vertical interleaving hardly increases power generation in terms of the whole wind farm. This research result has certain implications for the optimal layout of wind farms in practical applications, especially in sites with a well-defined prevailing wind direction.

Three-dimensional fine crust-mantle structure imaging and structural characteristics of Bohai Sea

This study used the consistency-constrained double-difference tomography method to invert 3D fine structure models of Vp, Vs, Vp/Vs at depths above 60 km, and precise relocation parameters of earthquakes in the Bohai Sea. According to the results, the velocity structures of P-wave and S-wave in the Bohai Sea area were highly similar and demonstrated noticeable lateral non-uniformity. The crust beneath the Tanlu Fault displayed a clear stratification structure, with a continuous velocity transition in the middle of the crust. The intricate crustal structure beneath the Zhangpeng Fault displayed high-velocity bodies in the crust and low-velocity anomalous zones connected to the top of the mantle in the lower section of the crust. The structural pattern in the deep crust of the Bohai Sea controls the occurrence characteristics of the Zhangpeng Fault and the Tanlu Fault. The earthquakes in the Bohai Sea area were concentrated mainly in the southern part near the Zhangpeng Fault. There is a good correspondence between the relocated earthquakes and velocity structure. There are many significant differences in crustal structure between the north and south of the Bohai Strait, and there are obvious velocity anomalies in the middle and upper crust. The distribution shape of high Vp/Vs value indicates that mantle material migration has occurred at the bottom of the crust. This paper provided important reference for further research on the relationship between deep tectonic features and tectonic activity in the North China Craton.

α-Tocopherol: New Perspectives and Challenges for Achieving the Sustainable Development Goals (SDG) Target.

Vitamin E (VE) is a lipophilic vitamin, and Evans and Bishop demonstrated the existence of a hitherto unrecognized dietary factor essential for normal reproduction in rat. During 100 years after the discovery, α-tocopherol (α-Toc) has been the representative species in VE homologues, and both naturally occurring and synthetically prepared α-Toc have been widely used and studied. Although it is indicated by a single-word VE, research on VE involves various chemical species. It is important to understand the fine structure and accurate characteristics of individual VE species when using VE. Each VE sample has compositional and/or isomer issues, and furthermore, the usability greatly varies depending on the modified species of esterification. The VE industry involves many interdisciplinary fields. Improvements in formulation technology and confirmation of the novel biological activity of VE greatly owns its utility and opens up new applications. As the interim period between the start and end of the agenda for Sustainable Development Goals (SDGs), in this minireview, the recent trends and future guidelines of VE, especially α- Toc, in relation to the SDGs have been demonstrated.

Fine structural features and proton conduction in zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC): Multinuclear solid-state NMR, impedance and FTIR spectroscopy study

The poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), i.e. one of the most biocompatible synthetic polymer, was synthesized using radical addition-fragmentation chain transfer (RAFT) polymerization and characterized by a wide set of experimental techniques, the 1H, 13C, 15N, 31P NMR, impedance and FTIR spectroscopy among those. The optimized synthesis conditions ensured the high product yield, high purity and narrow molecular weight distribution. The stereochemical content was determined from the complex shaped 13C MAS signal of CH3 group, and the relative content of the adsorbed water - from the 1H MAS spectra. The 1H13C and 1H31P cross-polarization kinetics were measured and processed using the Hirschinger and Raya spin dynamics model. Fine structural details, such as the partial (ca 10%) protonation of the internal PO4− group, the local order and the flexibility of the main chain were deduced. The thermal activation of proton conduction in the wet PMPC was deduced by impedance spectroscopy. The thermal boosting of proton mobility is driven via breaking the cage-like structures of water. This was confirmed by 1H MAS and FTIR spectroscopy. The experimental data for poly[2-(methacryloyloxy)ethyl trimethylammonium chloride] (PMETAC), i.e. cationic proton conducting polymer, which structure is closely related to PMPC, were revisited, compared and discussed.