Specific Structure Research Articles

Dough rheology and internal structure of bread produced with wheat flour partially substituted by buckwheat flour: A step towards enhancing nutritional value

Buckwheat flour is a pseudocereal that can be used to improve the nutritional value of staple food, such as bread. However, substituting wheat flour can be challenging due to potential loss of the final product's technological quality. Therefore, understanding the influence of buckwheat inclusion level on dough rheology and bread quality is essential. This study evaluated the effect of wheat flour substituted by buckwheat flour on dough rheology and bread quality over the staling process. Wheat flour was replaced by 0%, 10%, 20% and 30% of buckwheat flour and the resulting dough mixing properties, viscosity profile, gel texture, rheology behaviour and extensibility properties were analysed. Internal bread structure (C-Cell and confocal microscopy), specific volume, density and crumb texture profile were also assessed. The increase in buckwheat level gradually decreased flour water absorption (p < 0.05), dough stability and development time, with increased gluten weakening as evidenced by decreased C2 values (protein strength) of Mixolab. As a result, the dough was less resistant to extension, with decreased extensibility. The highest viscosity profile of the starch paste was observed with 30% buckwheat inclusion level, which may lead to faster bread staling process. A solid-like and elastic behaviour was observed in the rheology evaluation, suggesting an interaction between fibre and starch from buckwheat with gluten proteins. Although changes in dough rheology occurred, the bread quality remained unchanged at levels of up to 20% buckwheat level (p > 0.05), with similar specific volume, density, internal structure and texture profile compared to the control bread (0% buckwheat). In conclusion, buckwheat was found to be a viable wheat flour substitute with only minimal changes in dough behaviour and maintenance of bread technological quality, while enhancing the nutritional profile by increasing fibre content and total essential amino acid.

Personality adjectives in Serbian Tweets: An opening

There has been a great interest in investigating relations between personality and language use on the web or social media. Most of the recent studies are based on mining the users’ information available online and then using machine learning algorithms to predict their personality characteristics. On the other hand, a few studies have relied on the traditional lexical hypothesis when exploring personality under the assumption that personality-related attributes could be obtained from dictionaries. However, little is known about personality structure from Twitter - do data strictly reflect personality structure as represented by personality models, or as unique personality semantic patterns. The aim of the study was to assess and interpret the personality adjective-based structure contained in tweets. The data were collected from an open-access „Tweet-sr“ Serbian Twitter linguistic corpus (Ljubešić &amp; Klubička, 2014). Latent Dirichlet Allocation, a topic modeling technique, was conducted to extract topics and cosine similarity was used as a measure to determine topic similarities, as well as topic-personality dimensions’s similarities. The results showed that the optimal solution comprised four non-overlapping topics reflecting specific semantic structures. Topics did not replicate trait constructs but were modestly related to them. The largest similarities were found with Extraversion and Agreeableness, pointing out the conceptual importance of these traits when describing interpersonal behavior. Also, no inter-topic differences in category distributions were found, with the evaluation terms being the second most frequent in three topics. Although tweets are short-form text messages, they have the potential to communicate socially relevant information through personality descriptors.

Elaboration sites and prepositional meaning construction in English and Polish

Although prepositions are relational linguistic units of modest sizes, they can contribute a variety of different meanings to the constructions they are found in. The paper looks into the notion of e-site, which allows for conceptual elaboration of more schematic entities along the vertical and horizontal dimensions of the human conceptual representation. It argues that e-sites are useful for prepositional meaning description. First, e-sites come into play when schematic TRs and LMs of the preposition are elaborated by more specific conceptual structures, thereby, forming a vertical schematic-specific hierarchy of conceptual structures. Along the horizontal dimension, e-sites are responsible for the integration of the conceptual content of expressions which come together to form constructions. This type of elaboration finds its expression in the typology of languages (satellite- or verb-framed) proposed by Talmy (2000) and elaborated by Slobin (2005).

Human organ chips for regenerative pharmacology.

Human organs-on-chips (organ chips) are small microfluidic devices that allow human cells to perform complex organ-level functions invitro by recreating multi-cellular and multi-tissue structures and applying invivo-like biomechanical cues. Human Organ Chips are being used for drug discovery and toxicology testing as an alternative to animal models which are ethically challenging and often do not predict clinical efficacy or toxicity. In this mini-review, we summarize our presentation that reviewed the state of the art relating to these microfluidic culture devices designed to mimic specific human organ structures and functions, and the application of Organ Chips to regenerative pharmacology.

Dehydrogenation of Diethylene Glycol to Para-Dioxanone over Cu/SiO2 Catalyst: Effect of Structural and Surface Properties

Para-dioxanone, a typical monomer for high-performance biomedical polymers, is generally obtained from the catalytic dehydrogenation of diethylene glycol. In this work, Cu/SiO2 catalysts were prepared by two different methods and applied in diethylene glycol dehydrogenation. The effects of catalyst properties on the performance of para-dioxanone production were systematically explored by combined techniques. The results showed that the high specific surface area and regular pore structure of the catalyst promoted and stabilized the high dispersion of the copper species with an abundant Cu-Si interface, thereby providing numerous reactive sites. The appropriate Cu0/Cu+ ratio in the active components produced efficient synergy, which was responsible for the excellent dehydrogenation performance. In addition, the low surface acid density (0.532 μmol/m2) of the catalyst greatly reduced the occurrence of diethylene glycol dehydration, thus improving para-dioxanone selectivity over 90% with promising stability.

Transformation of film cooling performance with evolution of vortex structure for coolant jet with various swirl intensities

Advanced H/J series heavy-duty gas turbines are widely equipped with film cooling to protect turbine blades. Previous studies have shown that coolant swirl has an important influence on film cooling performance. However, there are few studies on the quantitative analysis of the coolant swirl intensity because of the swirl generated by the specific structure, and most of the research was carried out at relatively low temperatures. In this paper, a new method of defining the velocity field in the coolant inlet is used to quantitatively investigate the coolant swirl intensity. A numerical study of the film cooling performance for the coolant jet with various swirl intensities is conducted in the operating conditions of H series turbine vanes. The effects of the blowing ratio and coolant vorticity on the vortex structure and mixing process of the flow field are investigated emphatically, and the mechanisms for the variation of the film cooling effectiveness are analyzed. The results show that the film cooling effectiveness is greatly improved with the swirling coolant jet at high blowing ratios. When Ωn=40,000 /s, the area-averaged (L = 5D) film cooling effectiveness is 54 % higher than the non-swirling case. Ωn=20,000 /s is a critical value of the coolant vorticity. When Ωn>20,000 /s, the film coverage transforms significantly. Furthermore, the main vortical structures in a typical SJICF flow field with high blowing ratios and large vorticities are proposed. Compared with the non-swirling JICF, the additional coolant vortex and induced vortex appear in the SJICF. Under the influence of the two vortices, the coolant momentum is sacrificed for enhanced attachment to the wall resulting in the momentum advantage gradually transforming into the effectiveness advantage with the increase of the vorticity.

Biphasic amplitude oscillator characterized by distinct dynamics of trough and crest.

Biphasic amplitude dynamics (BAD) of oscillation have been observed in many biological systems. However, the specific topology structure and regulatory mechanisms underlying these biphasic amplitude dynamics remain elusive. Here, we searched all possible two-node circuit topologies and identified the core oscillator that enables robust oscillation. This core oscillator consists of a negative feedback loop between two nodes and a self-positive feedback loop of the input node, which result in the fast and slow dynamics of the two nodes, thereby achieving relaxation oscillation. Landscape theory was employed to study the stochastic dynamics and global stability of the system, allowing us to quantitatively describe the diverse positions and sizes of the Mexican hat. With increasing input strength, the size of the Mexican hat exhibits a gradual increase followed by a subsequent decrease. The self-activation of input node and the negative feedback on input node, which dominate the fast dynamics of the input node, were observed to regulate BAD in a bell-shaped manner. Both deterministic and statistical analysis results reveal that BAD is characterized by the linear and nonlinear dependence of the oscillation trough and crest on the input strength. In addition, combining with computational and theoretical analysis, we addressed that the linear response of trough to input is predominantly governed by the negative feedback, while the nonlinear response of crest is jointly regulated by the negative feedback loop and the self-positive feedback loop within the oscillator. Overall, this study provides a natural and physical basis for comprehending the occurrence of BAD in oscillatory systems, yielding guidance for the design of BAD in synthetic biology applications.

Hydrophilic and Apolar Hydration in Densely Grafted Cationic Brushes and Counterions with Large Mobilities.

We employ an all-atom molecular dynamics (MD) simulation framework to unravel water microstructure and ion properties for cationic [poly(2-(methacryloyloxy)ethyl) trimethylammonium chloride] (PMETAC) brushes with chloride ions as counterions. First, we identify locally separate water domains (or first hydration shells) each around {N(CH3)3}+ and the C═O functional groups of the PMETAC chain and one around the Cl- ion. These first hydration shells around the respective moieties overlap, and the extent of the overlap depends on the nature of the species triggering it. Second, despite the overlap, the water molecules in these domains demonstrate disparate properties dictated by the properties of the atoms and groups around which they are located. For example, the presence of the methyl groups makes the {N(CH3)3}+ group trigger apolar hydration as evidenced by the corresponding orientation of the dipole of the water molecules around the {N(CH3)3}+ moiety. These water molecules around the {N(CH3)3}+ group also have enhanced tetrahedrality compared to the water molecules constituting the hydration layer around the C═O group and the Cl- counterion. Our simulations also identify that there is an intervening water layer between the Cl- ion and {N(CH3)3}+ group: this layer prevents the Cl- ion from coming very close to the {N(CH3)3}+ group. As a consequence, there is a significantly large mobility of the Cl- ions inside the PMETAC brush layer. Furthermore, the C═O group of the polyelectrolyte (PE) chain, due to the partial negative charge on the oxygen atom and the specific structure of the PMETAC brush system, demonstrates strongly hydrophilic behavior and enforces a specific dipole response of water molecules analogous to that experienced by water around anionic species of high charge density. In summary, our findings confirm that PMETAC brushes undergo hydrophilic hydration at one site and apolar hydration at another site and ensure large mobility of the supported Cl- counterions.

SERS probing of fungal HET-s fibrils formed at neutral and acidic pH conditions

Advances in precision medical diagnostics require accurate and sensitive characterization of pathogens. In particular, health conditions associated with protein misfolding require an identification of proteinaceous amyloid fibrils or their precursors. These pathogenic entities express specific molecular structures, which require ultra-sensitive, molecular-level detection methods. A potentially transformative technique termed nanoplasmonics employs electro-optical phenomena in the vicinity of specially engineered metal nanostructures. A signature application of nanoplasmonics exploits enhancement of inelastic scattering of light in specific locations near metallic nanostructures, known as surface-enhanced Raman scattering (SERS). We applied SERS complemented with confocal microscopy imaging for ultra-sensitive, non-invasive, and label-free characterization of the fungal prion HET-s (218–289) as a model for β-sheet rich amyloid structures. This characterization employed Au-coated dielectric supports as plasmonic substrates. After confirming the formation of HET-s fibrils at both pH 7.5 and 2.8 using negative staining transmission electron microscopy, we subjected the fibril-containing solutions to multimodal analysis using confocal microscopy and SERS. The SERS spectral fingerprints from all HET-s samples expressed vibrational markers for β-structure, unstructured backbone, and aromatic side-chains. However, relative intensities of major SERS bands were pronouncedly different for the two pH levels. We have analyzed potential origins of the most pronounced SERS bands and proposed hypothetical mechanistic models that could explain the observed SERS fingerprints from HET-s fibrils grown at pH 7.5 and 2.8.

A Time–Frequency Residual Convolution Neural Network for the Fault Diagnosis of Rolling Bearings

A time–frequency residual convolution neural network (TFRCNN) was proposed to identify various rolling bearing fault types more efficiently. Three novel points about TFRCNN are presented as follows: First, by constructing a double-branch convolution network in the time domain and the frequency domain, the respective features in the time domain and the frequency domain were extracted to ensure the rich and complete feature representation of raw data sources. Second, specific residual structures were designed to prevent learning degradation of the deep network, and global average pooling was adopted to improve the network’s sparsity. Third, TFRCNN was better than the other models in terms of prediction accuracy, robustness, generalization ability, and convergence. The experimental results demonstrate that the prediction accuracy rate of TFRCNN, trained using mixing load data, reached 98.88 to 99.92% after optimizing the initial learning rate and choosing the optimizer and loss function. It was verified that TFRCNN can adaptively learn to extract deep fault features, accurately identify bearing fault conditions, and overcome the limitations of classical shallow feature extraction and classification methods, as well as common convolution neural networks. Hence, this investigation revealed TFRCNN’s potential for bearing fault diagnosis in practical engineering applications.

Liquid semen storage-induced alteration in the protein composition of turkey (Meleagris gallopavo) spermatozoa

Liquid storage of turkey semen without the loss of fertilizing ability is of practical interest to the poultry industry. However, fertility rates from liquid-stored turkey semen decline within a few hours. A clear cause of the decline in spermatozoa quality remains unidentified. Therefore, the purpose of the present study was to monitor the dynamics of proteomic changes in spermatozoa during 48 h of liquid storage by 2-dimensional difference in-gel electrophoresis coupled with matrix-assisted laser desorption/ionization mass spectrometry. A total of 57 protein spots were differentially expressed between fresh and stored spermatozoa; 42 spots were more and 15 were less abundant after 48 h of semen storage. Raw proteomic data are available via ProteomeXchange with identifier PXD043050. The selected differentially expressed proteins (DEPs) were validated by western blotting and localized in specific spermatozoa structures by immunofluorescence, such as the head (acrosin and tubulin α), midpiece (acrosin, aconitate hydratase 2, and glycerol-3-phosphate dehydrogenase) and tail (tubulin α). Most of the DEPs that changed in response to liquid storage were related to flagellum-dependent cell motility, energy derivation through oxidation of organic compounds and induction of fertilization, suggesting the complexity of the processes leading to the decrease in stored semen quality. The damaging effect of liquid storage on spermatozoa flagellum manifested as more microtubule proteins, such as tubulins and tektins, most likely formed by posttranslational modifications, tubulin α relocation from the tail to the sperm head, which appeared after 48 h of semen storage, and decreases in fibrous shelf proteins at the same time. Motility could be affected by dysregulation of Ca2+-binding proteins and disturbances in energy metabolism in spermatozoa flagellum. Regarding sperm mitochondria, DEPs involved in energy derivation through the oxidation of organic compounds indicated disturbances in fatty acid beta oxidation and the tricarboxylic acid cycle as possible reasons for energy deficiency during liquid storage. Disturbances in acrosin and 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase zeta may be involved in rapid declines in the fertility potential of stored turkey spermatozoa. These results showed the complexity of the processes leading to a decrease in stored semen quality and broadened knowledge of the detrimental effects of liquid storage on turkey spermatozoa physiology.

Development of a procedure for model selection in machine learning-based methods for structural damage detection

Output-only methods based on machine/deep-learning algorithms are highly practical approaches for timely detecting potential damages in civil structures as they directly employ measured vibration signals but do notrequire exact knowledge of input loading nor the service interruption for manual inspection. However, there isno one-size-fits-all model that is optimal for all problems in different perspectives; hence, it is necessary todiscover the advantages as well as drawbacks of different models, then leverage these understandings to selectthe most appropriate model for specific structures in reality. Therefore, this study develops a framework thatfacilitate the model selection by extensively comparing various machine learning-based methods ranging fromrelatively simple ones such as Na¨ıve Bayes to complex ones such as the extreme boosting tree-based ensemblemodel. The framework can provide comparison results include various aspects such as model complexity, training time, detection accuracy, and inference time.

Layered manganese oxides structures: Micro‐Raman and selected mobile Raman spectroscopic studies

AbstractThe main structural building blocks that form manganese oxides are MnO6 octahedra; these share corners and edges to construct specific structures, which can either be tunneled or layered. In the layered structures, that is, phyllomanganates, the MnO6 octahedra form sheets, which, in turn, alternate with sheets of metal oxides and H2O. These metal ions can vary (Zn, Co, Ni, Al, Li, …) and give rise to an entire range of different metal oxides. The characterization of these layered materials is important as they have various economical/industrial applications. Birnessite‐type materials, a specific type of layered manganese oxides, are widely studied for their use as cathode materials in alkali‐ion batteries. Phyllomanganates are also commonly found as constituents in sediments and soils or as coatings on rock surfaces. Their natural occurrence as black colored components have ensured that these minerals were also applied as pigments in archaeological and historical contexts. They are, for example, often found in rock art paintings and on pottery. As the oxides are used in unique archaeological objects, Raman spectroscopy is an evident choice for characterization due to its non‐destructive nature of analysis. In the current study, five mineral samples of (layered) manganese oxides are analyzed with different Raman instrumentations, including mobile systems and a benchtop micro‐Raman setup. The characterization of each selected manganese oxide and their comparison with literature data is discussed for the micro‐Raman instrumentation. In addition, the ability of identifying and characterizing layered manganese oxides and the possible challenges when using mobile instrumentation are discussed as well.

An experimental study of the effect of individual upper airway anatomical features on the deposition of dry powder inhaler formulations

This study aims to investigate the effects of different pharynx anatomical features on the delivery of inhaled aerosols. Six in-vitro upper airway models reconstructed using anatomical images acquired by Magnetic Resonance Imaging (MRI) were used for the experiments. A geometrically accurate airway model was produced, and five other different airway models, each missing one or more specific anatomical features: the uvula, epiglottis, and/or soft palate, were derived from the original model. Hence, the geometrical boundaries of the six models were the same except at regions where specific anatomical structures were removed, and this was done to allow meaningful comparisons between the different geometries to be made using specific measurements. Spray-dried mannitol powder (volume median particle size and span were 3.22 μm and 1.90 μm, respectively) was loaded into a capsule-based dry powder inhaler with different resistance, an Osmohaler™ (low resistance), or Handihaler® (high resistance), attached to the inlet of the airway model, which its outlet was connected to a Next-Generation Impactor (NGI). The studies were performed using flow rates of 30 and 60 LPM. High-performance liquid chromatography (HPLC) was used to quantify the mass deposition of particles in different stages of the NGI and airway replicas. Results from this study show that widening the space between the oral cavity and oropharynx, exemplified by one of the six replicas developed, significantly decreases upper airway deposition as well as increases the fine particle fraction. The case with the highest deposition (63.5%) occurred in the pharynx replica with the soft palate present (at 60 LPM with the Hanihaler), while the lowest deposition (26.0%) occurred in the replica without the soft palate and epiglottis (at 30 LPM with the Osmohaler). This study highlights that in addition to the resistance of the inhalers, their interactions with the human airway anatomical features are likely to play important roles in the subsequent lung dose. Results from this study are novel because while the effects of different inhaler resistance in a given airway replica is known, the effects contributed by specific pharynx anatomical features on particle transport behaviour have not been studied experimentally or reported on in the literature. This study shows that space adjacent to the soft palate affects particle deposition dramatically but the effect appears to be more significant when using the Handihaler and for the high flow rate cases.

Metal−Organic Framework CPO-27 Derivatives As Non-Precious Metal Catalyst for Anion Exchange Membrane Fuel Cell

Fuel cell stands as an environmentally friendly technology harnessing the power of hydrogen to generate clean water. In the range of fuel cell types, the anion exchange membrane fuel cell (AEMFC) stands out, effectively converting chemical energy to electricity without relying on platinum catalyst. Nonetheless, platinum catalyst is still used in addressing the sluggishness of the oxygen reduction reaction (ORR) during AEMFC operation. The scarcity and expense of platinum, however, hinder its widespread adoption. Furthermore, in the alkaline environment, platinum surface is covered with OH species, impeding active sites and diminishing electrochemical activity. Consequently, seeking an efficient, stable, and abundant platinum substitute is a primary target in the development of fuel cell.This study focuses on the development of the non-precious metal catalyst for the ORR in AEMFC. The catalyst, denoted as NiCo2-CPO-27/PCN, is derived from a carbon nanorod structure obtained from the metal-organic framework (CPO-27). Through the optimized process, the catalyst demonstrates the distinct carbon nanorod configuration. Additionally, the NiCo2-CPO-27/PCN catalyst exhibits enhanced ORR activity, achieving the electron transfer number of 3.99, which closely approaches the ideal four-electron transfer number. This improvement in activity is attributed to factors such as the specific structure, heteroatom contribution, and coordination arrangement of the catalyst.

Branch-leaf structural VS2@C/TiO2 anode for high-performance lithium-ion batteries

Heterogeneous materials combine the advantage of each component through the synergy effect to become promising electrode materials for lithium-ion batteries (LIBs). Designing heterojunctions with specific structures can better show their electrochemical performance. In this work, we fabricated VS2 nanosheets perpendicular to the C/TiO2 nanotube (VS2@C/TiO2) composite with a “branch-leaf” structure by an electrospinning-carbonization-solvothermal method. Notably, the interior of the C/TiO2 nanotube consists of small-sized TiO2 nanoparticles, which guarantees high electrochemical reactivity. The presence of carbon not only accelerates charge transfer across the interface of carbon-TiO2 but also serves as an anchor for the growth of VS2 nanosheet by CSV bonding, thus enhancing the structural stability of the electrode. As anode for LIBs, the VS2@C/TiO2 electrode exhibits a high reversible capacity of 748 mAh g−1 and 324.2 mAh g−1 at 100 mA g−1 and 1 A g−1, respectively. This work highlights the unique “branch-leaf” design of VS2@C/TiO2, which offers a new prospect for developing high-performance heterogeneous electrodes for LIBs.

Manganese and Nitrogen Doped Biomass-Based Activated Carbons As Electrocatalysts for Oxygen Reduction and Water Splitting

In this study, an efficient manganese (Mn) and nitrogen (N) co-doped carbon materials were prepared using the three raw materials, namely alder charcoal (Mn-N-CAC), hydrothermally carbonised birch wood (Mn-N-CW), and black liquor (Mn-N-CBL). At first, biomass-based activated carbon materials were synthesized. Mn and N were co-doped in one step using the reaction mixture containing Mn2+ ions source, activated carbon material, and dicyandiamide (DCDA) in dimethylformamide (DMF). DMF was evaporated and the mixture was treated for 60 min at a temperature of 800 ºC. The specific surface area, morphology, structure, and composition of Mn-N-C were determined using BET, TEM, XPS, Raman, XRD, and ICP-OES. Activity of resulted Mn-N-C materials was evaluated for oxygen reduction (ORR) as well as for hydrogen and oxygen evolution (HER and OER) using linear-sweep voltammetry (LSV) with a rotating disk electrode (RDE) in alkaline media.It was found that all Mn-N-C materials had a high specific surface area in the range of approximately of 1800 to 2200 m2 g-1 but the Mn-N-CBL presented a higher contribution of the mesopores in comaparison to Mn-N-CAC and Mn-N-CW which are similar. All synthesized Mn-N-C materials exhibit excellent electrocatalytic activity for ORR with the onset and half-wave potentials of approximately 0.88‒0.90 and 0.80‒0.84 V, respectively, showing the 4e‒ electrons transfer path in 0.1 M KOH solution. The Mn-N-C materials also show enhanced activity for HER and OER in alkaline media. Acknowledgment The “Sustainably Produced Carbon Nanomaterials for Energy Applications (SuNaMa)” benefits from a 988000 € grant from Iceland, Liechtenstein, and Norway through the EEA Grants. The aim of the project is to develop innovative, high-performance, highly conductive, electrocatalytically active, durable, cost-effective, and high surface area nanocarbon materials. Project contract with the Research Council of Lithuania (LMTLT) No. is S-BMT-21-12 (LT08-2-LMT-K-01-055).

Real-Time Monitoring of Mitochondrial Damage Using Conjugated Oligoelectrolytes.

Conjugated oligoelectrolytes (COEs) comprise a class of fluorescent reporters with tunable optical properties and lipid bilayer affinity. These molecules have proven effective in a range of bioimaging applications; however, their use in characterizing specific subcellular structures remains restricted. Such capabilities would broaden COE applications to understand cellular dysfunction, cell communication, and the targets of different pharmaceutical agents. Here, we disclose a novel COE derivative, COE-CN, which enables the visualization of mitochondria, including morphological changes and lysosomal fusion upon treatment with depolarizing agents. COE-CN is characterized by the presence of imidazolium solubilizing groups and an optically active cyanovinyl-linked distyrylbenzene core with intramolecular charge-transfer characteristics. Our current understanding is that the relatively shorter molecular length of COE-CN leads to weaker binding within lipid bilayer membranes, which allows sampling of internal cellular structures and ultimately to different localization relative to elongated COEs. As a means of practical demonstration, COE-CN can be used to diagnose cells with damaged mitochondria via flow cytometry. Coupled with an elongated COE that does not translocate upon depolarization, changes in ratiometric fluorescence intensity can be used to monitor mitochondrial membrane potential disruption, demonstrating the potential for use in diagnostic assays.

(Invited) Stable Layered Oxyhalide Photocatalysts for Visible-Light-Induced Water Splitting

Water splitting using photocatalysts has attracted considerable attention for producing H2 as a clean energy carrier, while the effective utilization of visible light is imperative to achieve the desired efficiency for practical applications. Recently, mixed-anion compounds such as oxynitrides have been intensively studied as promising candidates since one can expect that higher energy p orbitals of non-oxide anions (e.g., N-2p) elevate their VBM values. Unfortunately, most of them are subject to facile self-oxidation by photogenerated holes, while highly dispersed cocatalyst particles certainly improve the stability of some oxynitrides.Recently, we have revealed that some layered perovskite oxyhalides fulfil the necessary conditions for visible-light-induced water splitting due to their unique VBMs. For example, Bi4NbO8Cl belongs to the n = 1 members of the Sillén–Aurivillius perovskite family [(Bi2O2)2X]3+[A n -1BnO3n+1]3, which is composed of fluorite [Bi2O2], perovskite [NbO4], and halogen [Cl] layers as depicted in Figure 1. DFT calculations show that the VBM mainly consists of O-2p orbitals instead of Cl-3p, but its position determined by electrochemical measurement is much more negative (ca. 2.2 V vs. SHE) than those of conventional metal oxides (ca. 3.0 V). The significantly elevated VBMs of Bi4NbO8Cl can be understood by the strong hybridization between electron-filled Bi-6s and O-2p with the help of empty Bi-6p orbitals. In addition, Madelung site potential analysis for Bi4NbO8Cl indicated that the oxygen sites in the fluorite layer were electrostatically destabilized, which also certainly contributed to the elevation of the VBM that mainly consists of O-2p. Consequently, Bi4NbO8Cl possesses both a narrow band gap (2.4 eV) for visible light absorption up to ca. 500 nm and a more negative CBM (ca.–0.2 V vs. SHE) than the water reduction potential, which were testified by the substantial generation of H2 or O2 in the presence of an electron donor or acceptor, respectively. The substantially high durability against self-oxidative deactivation was also confirmed by the long-term water splitting in a Z-scheme system in which Bi4NbO8Cl was employed as the OEP. Since O– anions are known to be relatively stable, photogenerated holes populated at the O-2p orbitals will not lead to self-oxidative decomposition but rather to the oxidation of water.More oxyhalides with various perovskite layers (n) have been explored. However, reports on the synthesis of multiple-layered (n ≥ 2) perovskites were limited, probably due to the severe conditions required for their synthesis in the conventional solid state reaction. To solve this problem, a new two-step synthesis method including polymerized complex synthesis and a “bricklaying” synthesis were developed; providing a wide variety of new oxyhalides applicable to visible-light-induced water splitting. We also demonstrate that a oxyiodides such as Ba2Bi3Nb2O11I not only has access to a wider range of visible light than its chloride and bromide counterparts, but also exhibit much higher activity due to longer lifetime of photogenerated carriers.These studies on new oxyhalide materials provide new strategies for developing stable photocatalysts for visible-light-induced water splitting by manipulating the interaction between the s orbitals of post-transition metals (e.g., Bi-6s) and O-2p orbitals in the specific crystal structure.

Expression of influenza A virus glycan receptor candidates in mallard, chicken, and tufted duck.

Influenza A virus (IAV) pandemics result from interspecies transmission events within the avian reservoir and further into mammals including humans. Receptor incompatibility due to differently expressed glycan structures between species has been suggested to limit zoonotic IAV transmission from the wild bird reservoir as well as between different bird species. Using glycoproteomics, we have studied the repertoires of expressed glycan structures with focus on putative sialic acid-containing glycan receptors for IAV in mallard, chicken and tufted duck; three bird species with different roles in the zoonotic ecology of IAV. The methodology used pinpoints specific glycan structures to specific glycosylation sites of identified glycoproteins and was also used to successfully discriminate α2-3- from α2-6-linked terminal sialic acids by careful analysis of oxonium ions released from glycopeptides in tandem MS/MS (MS2), and MS/MS/MS (MS3). Our analysis clearly demonstrated that all three bird species can produce complex N-glycans including α2-3-linked sialyl Lewis structures, as well as both N- and O- glycans terminated with both α2-3- and α2-6-linked Neu5Ac. We also found the recently identified putative IAV receptor structures, Man-6P N-glycopeptides, in all tissues of the three bird species. Furthermore, we found many similarities in the repertoires of expressed receptors both between the bird species investigated and to previously published data from pigs and humans. Our findings of sialylated glycan structures, previously anticipated to be mammalian specific, in all three bird species may have major implications for our understanding of the role of receptor incompatibility in interspecies transmission of IAV.