Significant anisotropic deformation and optical shifts in stretched cholesteric liquid crystal elastomers.

This study explores the opto-mechanical response of cholesteric liquid crystal elastomers (CLCEs) subjected to uniaxial stretching along the x-axis, perpendicular to their helical z-axis. A definitive crossover is observed in the strain (εx) dependencies of various optical and mechanical properties, such as the transmission spectra, degree of mesogen orientation, Poisson's ratios, and tensile stress. At low strains, CLCEs exhibit a blue shift in the selective reflection band due to a reduction in the helical pitch, accompanied by a decrease in reflection selectivity for circularly polarized light. Beyond a certain critical strain further pitch alterations halt. This strain regime is marked by substantial anisotropic lateral contractions without any z-axis contraction, as indicated by a Poisson's ratio (µxz) of zero. Within this intermediate strain regime, local directors predominantly reorient towards the x-direction within the xy-plane, resulting in a quasi-plateau of tensile stress. Approaching a higher critical strain a complete loss of reflective selectivity occurs. Past this threshold, while the mechanical responses resemble those of isotropic conventional rubber, they retain a periodic structure albeit without phase chirality. These observed features are accounted for by the Mao-Terentjev-Warner model, especially when the network anisotropy parameter is adjusted to match the critical strain magnitude associated with the cessation of selective reflection.

Supramolecular Polymer Polymorphism: Spontaneous Helix-Helicoid Transition through Dislocation of Hydrogen-Bonded π-Rosettes.

Polymorphism, a phenomenon whereby disparate self-assembled products can be formed from identical molecules, has incited interest in the field of supramolecular polymers. Conventionally, the monomers that constitute supramolecular polymers are engineered to facilitate one-dimensional aggregation and, consequently, their polymorphism surfaces primarily when the states of assembly differ significantly. This engenders polymorphs of divergent dimensionalities such as one- and two-dimensional aggregates. Notwithstanding, realizing supramolecular polymer polymorphism, wherein polymorphs maintain one-dimensional aggregation, persists as a daunting challenge. In this work, we expound upon the manifestation of two supramolecular polymer polymorphs formed from a large discotic supramolecular monomer (rosette), which consists of six hydrogen-bonded molecules with an extended π-conjugated core. These polymorphs are generated in mixtures of chloroform and methylcyclohexane, attributable to distinctly different disc stacking arrangements. The face-to-face (minimal displacement) and offset (large displacement) stacking arrangements can be predicated on their distinctive photophysical properties. The face-to-face stacking results in a twisted helix structure. Conversely, the offset stacking induces inherent curvature in the supramolecular fiber, thereby culminating in a hollow helical coil (helicoid). While both polymorphs exhibit bistability in nonpolar solvent compositions, the face-to-face stacking attains stability purely in a kinetic sense within a polar solvent composition and undergoes conversion into offset stacking through a dislocation of stacked rosettes. This occurs without the dissociation and nucleation of monomers, leading to unprecedented helicoidal folding of supramolecular polymers. Our findings augment our understanding of supramolecular polymer polymorphism, but they also highlight a distinctive method for achieving helicoidal folding in supramolecular polymers.

The structural changes of a bovine casein micelle during temperature change; in situ observation over a wide spatial scale from nano to micrometer.

Bovine milk is the complex colloidal system containing nano to micrometer scale components. Earlier, our research group reported the structural changes in bovine casein micelles in the temperature range of 10-40 °C by in situ small-angle X-ray scattering (SAXS) [H. Takagi, T. Nakano, T. Aoki and M. Tanimoto, Food Chem., 2022, 393, 133389]. In this study, we extend our previous research by investigating the temperature-associated structural alterations in casein micelles over a wide spatial scale using in situ SAXS and ultra-SAXS (USAXS). Furthermore, the temperature dependences of various physical properties of the casein micelles were investigated by analyzing the SAXS intensities. The USAXS results showed that micelles formed 1-dimensional aggregates and that these aggregate structures did not change in the temperature range of 10-40 °C. Changes in electron densities calculated from SAXS intensities showed that the voluminosity reduced and the weight fraction of protein inside the micelles increased during the heating process. The number of water domains in a micelle decreased when the temperature increased from 10 to 40 °C, but did not substantially change in the cooling run at a rate of 1 °C min-1. The number of colloidal calcium phosphate (NCCP) in a micelle can also be calculated from the SAXS intensities; NCCP increases upon heating. This study on the behavior of casein micelles with respect to temperature change in milk over a wide spatial scale showed that the casein micelle structure was sensitive to temperature and can change dramatically with temperature variations.

Realizing Vat-Photocycloaddition 3D Printing with Recyclable Synthetic Photorheological Silicone Fluids.

Synthetic silicone rubbers are finding a broad spectrum of applications, yet there is a demand for developing greener silicone rubbers with processability, recyclability, and reversible tunability in their mechanical properties. Here, a recyclable photorheological silicone fluid (RPSF) is developed, which realizes completely reversible wavelength-selective liquid-rubber conversion upon photoirradiation, relying on the reversible photocycloaddition of coumarin upon alternating irradiation of light with wavelengths of 365 (UV365 ) and 254 nm (UV254 ). Rheological studies demonstrate that the storage modulus of the developed RPSF increases by a factor of more than 100 000 upon UV365 irradiation to reach 20-50 kPa, while it decreases to ≈0.01 kPa upon UV254 irradiation. The reversibility of the photocycloaddition of coumarin enables the application of RPSF as a photodismantlable adhesive. Furthermore, unprecedented vat-photocycloaddition 3D printing of silicone rubber is realized by taking advantage of the excellent photocurability, that is, the dramatic increase in viscoelasticity upon UV365 irradiation.

Diarylethene-Powered Light-Induced Folding of Supramolecular Polymers.

Helical folding of randomly coiled linear polymers is an essential organization process not only for biological polypeptides but also for synthetic functional polymers. Realization of this dynamic process in supramolecular polymers (SPs) is, however, a formidable challenge because of their inherent lability of main chains upon changing an external environment that can drive the folding process (e.g., solvent, concentration, and temperature). We herein report a photoinduced reversible folding/unfolding of rosette-based SPs driven by photoisomerization of a diarylethene (DAE). Temperature-controlled supramolecular polymerization of a barbiturate-functionalized DAE (open isomer) in nonpolar solvent results in the formation of intrinsically curved, but randomly coiled, SPs due to the presence of defects. Irradiation of the randomly coiled SPs with UV light causes efficient ring-closure reaction of the DAE moieties, which induces helical folding of the randomly coiled structures into helicoidal ones, as evidenced by atomic force microscopy and small-angle X-ray scattering. The helical folding is driven by internal structure ordering of the SP fiber that repairs the defects and interloop interaction occurring only for the resulting helicoidal structure. In contrast, direct supramolecular polymerization of the ring-closed DAE monomers by temperature control affords linearly extended ribbon-like SPs lacking intrinsic curvature that are thermodynamically less stable compared to the helicoidal SPs. The finding represents an important concept applicable to other SP systems; that is, postpolymerization (photo)reaction of preorganized kinetic structures can lead to more thermodynamically stable structures that are inaccessible directly through temperature-controlled protocols.

Pivotal role of the carbohydrate recognition domain in self-interaction of CLEC4A to elicit the ITIM-mediated inhibitory function in murine conventional dendritic cells in vitro.

C-type lectin receptors (CLRs), pattern recognition receptors (PRRs) with a characteristic carbohydrate recognition domain (CRD) in the extracellular portion, mediate crucial cellular functions upon recognition of glycosylated pathogens and self-glycoproteins. CLEC4A is the only classical CLR that possesses an intracellular immunoreceptor tyrosine-based inhibitory motif (ITIM), which possibly transduces negative signals. However, how CLEC4A exerts cellular inhibition remains unclear. Here, we report that the self-interaction of CLEC4A through the CRD is required for the ITIM-mediated suppressive function in conventional dendritic cells (cDCs). Human type 2 cDCs (cDC2) and monocytes display a higher expression of CLEC4A than cDC1 and plasmacytoid DCs (pDCs) as well as B cells. The extracellular portion of CLEC4A specifically binds to a murine cDC cell line expressing CLEC4A, while its extracellular portion lacking the N-glycosylation site or the EPS motif within the CRD reduces their association. Furthermore, the deletion of the EPS motif within the CRD or ITIM in CLEC4A almost completely impairs its suppressive effect on the activation of the murine cDC cell line, whereas the absence of the N-glycosylation site within the CRD exhibits partial inhibition on their activation. On the other hand, antagonistic monoclonal antibody (mAb) to CLEC4A, which inhibits the self-interaction of CLEC4A and its downstream signaling in murine transfectants, enhances the activation of monocytes and monocyte-derived immature DCs upon stimulation with a Toll-like receptor (TLR) ligand. Thus, our findings suggest a pivotal role of the CRD in self-interaction of CLEC4A to elicit the ITIM-mediated inhibitory signal for the control of the function of cDCs.

Markov chain analysis for the neonatal inpatient flow in a hospital.

Discrete-time Markov chain and queueing-theoretic models are used to quantitatively formulate the flow of neonatal inpatients over several wards in a hospital. Parameters of the models are determined from the operational analysis of the record of the numbers of admission/departure for each ward every day and the order log of patient movement from ward to ward for two years provided by the Medical Information Department of the University of Tsukuba Hospital in Japan. Our formulation is based on the analysis of the precise routes (the route of an inpatient is defined as a sequence of the wards in which he/she stays from admission to discharge) and their length-of-stay (LoS) in days in each ward on their routes for all neonatal inpatients. Our theoretical model calculates the probability distribution for the number of patients staying in each ward per day which agrees well with the corresponding histogram observed for each ward as well as for the whole hospital. The proposed method can be used for the long-term capacity planning of hospital wards with respect to the probabilistic bed utilization.

Non-uniform Photoinduced Unfolding of Supramolecular Polymers Leading to Topological Block Nanofibers.

Synthesis of one-dimensional nanofibers with distinct topological (higher-order structural) domains in the same main chain is one of the challenging topics in modern supramolecular polymer chemistry. Non-uniform structural transformation of supramolecular polymer chains by external stimuli may enable preparation of such nanofibers. To demonstrate feasibility of this post-polymerization strategy, we prepared a photoresponsive helically folded supramolecular polymers from a barbiturate monomer containing an azobenzene-embedded rigid π-conjugated scaffold. In contrast to previous helically folded supramolecular polymers composed of a more flexible azobenzene monomer, UV-light induced unfolding of the newly prepared helically folded supramolecular polymers occurred nonuniformly, affording topological block copolymers consisting of folded and unfolded domains. The formation of such blocky copolymers indicates that the photoinduced unfolding of the helically folded structures initiates from relatively flexible parts such as termini or defects. Spontaneous refolding of the unfolded domains was observed after visible-light irradiation followed by aging to restore fully folded structures.

Plasmacytoid dendritic cells are crucial for the initiation of inflammation and T cell immunity in vivo.

Plasmacytoid dendritic cells (pDCs) are characterized as type I interferon-producing cells that engage endosomal toll-like receptors (TLRs) and exclusively express sialic acid binding Ig-like lectin (Siglec)-H. However, their role in vivo remains unclear. Here we report a critical role for pDCs in the regulation of inflammation and T cell immunity in vivo by using gene-targeted mice with a deficiency of Siglec-H and conditional ablation of pDCs. pDCs were required for inflammation triggered by a TLR ligand as well as by bacterial and viral infections. pDCs controlled homeostasis of effector and regulatory CD4(+) T cells. Upon antigenic stimulation and microbial infection, pDCs suppressed the induction of CD4(+) T cell responses and participated in the initiation of CD8(+) T cell responses. Furthermore, Siglec-H appeared to modulate the function of pDCs in vivo. Thus, our findings highlight previously unidentified roles of pDCs and the regulation of their function for the control of innate and adaptive immunity.

Topological Impact on the Kinetic Stability of Supramolecular Polymers.

Kinetically formed metastable molecular assemblies have attracted increasing interest especially in the field of supramolecular polymers. In most cases, metastable assemblies are ensemblies of aggregates based on the same supramolecular motif but with different lengths or sizes, and therefore their kinetic stabilities are experimentally indistinguishable. Herein, we demonstrate a topological effect on kinetic stabilities in a complex mixture of metastable supramolecular polymers. Our azobenzene-incorporated monomer upon heating in nonpolar solvent at ambient temperature kinetically forms complex mixtures of supramolecular polymers with cyclized and open-ended randomly coiled topologies. Upon further heating, we obtained thermodynamically stable twisted fibrils organizing into crystalline fibers. Through the direct visualization of the complex supramolecular polymer mixtures by atomic force microscopy, we demonstrate that the cyclized supramolecular polymer has superior kinetic stability compared to the open-ended species toward the thermal transformation into twisted fibrils. Since the superior kinetic stability of the cyclized species can be attributed to the absence of aggregate termini, we could convert them fully into the thermodynamic species through photoinduced opening of the cyclized structures.

Critical role of plasmacytoid dendritic cells in induction of oral tolerance.

BACKGROUND: Exposure to dietary constituents through the mucosal surface of the gastrointestinal tract generates oral tolerance that prevents deleterious T cell-mediated immunity. Although oral tolerance is an active process that involves emergence of CD4+ forkhead box p3 (Foxp3)+ regulatory T (Treg) cells in gut-associated lymphoid tissues (GALTs) for suppression of effector T (Teff) cells, how antigen-presenting cells initiate this process remains unclear. OBJECTIVE: We sought to determine the role of plasmacytoid dendritic cells (pDCs), which are known as unconventional antigen-presenting cells, in establishment of oral tolerance. METHODS: GALT-associated pDCs in wild-type mice were examined for their ability to induce differentiation of CD4+ Teff cells and CD4+Foxp3+ Treg cells in vitro. Wild-type and pDC-ablated mice were fed oral antigen to compare their intestinal generation of CD4+Foxp3+ Treg cells and induction of oral tolerance to protect against Teff cell-mediated allergic inflammation. RESULTS: GALT-associated pDCs preferentially generate CD4+Foxp3+ Treg cells rather than CD4+ Teff cells, and such generation requires an autocrine loop of TGF-ß for its robust production. A deficiency of pDCs abrogates antigen-specific de novo generation of CD4+Foxp3+ Treg cells occurring in GALT after antigenic feeding. Furthermore, the absence of pDCs impairs development of oral tolerance, which ameliorates the progression of delayed-type hypersensitivity and systemic anaphylaxis, as well as allergic asthma, accompanied by an enhanced antigen-specific CD4+ Teff cell response and antibody production. CONCLUSION: pDCs are required for establishing oral tolerance to prevent undesirable allergic responses, and they might serve a key role in maintaining gastrointestinal immune homeostasis.

Topology-Reset Execution: Repeatable Postcyclization Recyclization of Cyclic Polymers.

Repeatable topological transformation of polymers for the modulation of material functions is a challenge. We have developed a method for repeatedly resetting a cyclic macromolecular architecture to a linear architecture by photostimulation, namely, topology-reset execution (T-rex) based on the photochemistry of hexaarylbiimidazoles (HABIs). We synthesized cyclic poly(dimethylsiloxane)s (PDMSs) of various ring sizes with HABIs linked in the chains. UV irradiation of the cyclic PDMSs produced telechelic linear PDMSs with triphenylimidazolyl radical (TPIR) end groups. After termination of UV irradiation, end-to-end recyclization occurred by the recoupling of TPIRs. The cyclic PDMSs also responded to ultrasound, which decreased their molecular weight (MW) by site-specific cleavage of in-chain HABI moieties, and we are able to reset the MWs by subsequent phototriggered T-rex. Furthermore, T-rex enabled solvent-free switching of the rheological properties of the materials while retaining the liquid character of PDMS.

Regulatory Dendritic Cells.

Dendritic cells (DCs) comprise heterogeneous subsets, functionally classified into conventional DCs (cDCs) and plasmacytoid DCs (pDCs). DCs are considered to be essential antigen (Ag)-presenting cells (APCs) that play crucial roles in activation and fine-tuning of innate and adaptive immunity under inflammatory conditions, as well as induction of immune tolerance to maintain immune homeostasis under steady-state conditions. Furthermore, DC functions can be modified and influenced by stimulation with various extrinsic factors, such as ligands for pattern-recognition receptors (PRRs) and cytokines. On the other hand, treatment of DCs with certain immunosuppressive drugs and molecules leads to the generation of tolerogenic DCs that show downregulation of both the major histocompatibility complex (MHC) and costimulatory molecules, and not only show defective T-cell activation, but also possess tolerogenic properties including the induction of anergic T-cells and regulatory T (Treg) cells. To develop an effective strategy for Ag-specific intervention of T-cell-mediated immune disorders, we have previously established the modified DCs with moderately high levels of MHC molecules that are defective in the expression of costimulatory molecules that had a greater immunoregulatory property than classical tolerogenic DCs, which we therefore designated as regulatory DCs (DCreg). Herein, we integrate the current understanding of the role of DCs in the control of immune responses, and further provide new information of the characteristics of tolerogenic DCs and DCreg, as well as their regulation of immune responses and disorders.

Supramolecular Polymerization of Supermacrocycles: Effect of Molecular Conformations on Kinetics and Morphology.

Intricately designed π-conjugated molecules containing interactive groups can be used to generate supramolecular polymers with outstanding structural and functional properties. To construct such supramolecular polymers, the non-covalent synthesis of supermacrocyclic monomers from relatively simple molecules represents an attractive strategy, although this has been rarely exploited. Here, we report the supramolecular polymerization of two barbiturate-naphthalene derivatives that circularly hexamerize by hydrogen bonding. The two molecules contain an aliphatic "wedge" unit with either an ether or ester linkage. This subtle difference is amplified into distinct features both in terms of the morphology of the supramolecular polymers and the polymerization process. The degrees of conformational freedom of the wedge unit determine the stacking of the supermacrocycles, as is evident from 2D X-ray diffraction analyses on the aligned fibers. The differences in stacking impart the supramolecular polymer fibers with different morphological features (cylindrical or helical), which are reflected in the properties of concentrated solutions (suspension or gel). The degrees of conformational freedom of the wedge unit also affect the polymerization kinetics, in which the more flexible ether linkage induces pathway complexity by the formation of off-pathway aggregates.

Queueing network model for obstetric patient flow in a hospital.

A queueing network is used to model the flow of patients in a hospital using the observed admission rate of patients and the histogram for the length of stay for patients in each ward. A complete log of orders for every movement of all patients from room to room covering two years was provided to us by the Medical Information Department of the University of Tsukuba Hospital in Japan. We focused on obstetric patients, who are generally hospitalized at random times throughout the year, and we analyzed the patient flow probabilistically. On admission, each obstetric patient is assigned to a bed in one of the two wards: one for normal delivery and the other for high-risk delivery. Then, the patient may be transferred between the two wards before discharge. We confirm Little's law of queueing theory for the patient flow in each ward. Next, we propose a new network model of M/G/ ∞ and M/M/ m queues to represent the flow of these patients, which is used to predict the probability distribution for the number of patients staying in each ward at the nightly census time. Although our model is a very rough and simplistic approximation of the real patient flow, the predicted probability distribution shows good agreement with the observed data. The proposed method can be used for capacity planning of hospital wards to predict future patient load in each ward.

SIGNR1-mediated phagocytosis, but not SIGNR1-mediated endocytosis or cell adhesion, suppresses LPS-induced secretion of IL-6 from murine macrophages.

C-type lectin receptors (CLRs) serve as phagocytosis receptors for pathogens and also function as adhesion molecules and in the recognition and endocytosis of glycosylated self-antigens. In the present study, we demonstrated that phagocytosis mediated by a mouse mannose-binding CLR, SIGNR1 significantly suppressed the LPS-induced secretion of the specific pro-inflammatory cytokines from the resident peritoneal macrophages and the mouse macrophage-like cells that express SIGNR1 (RAW-SIGNR1). LPS-induced secretion of IL-6 from peritoneal macrophages suppressed in response to uptake of oligomannose-coated liposomes (OMLs), and the suppression was partly inhibited by treatment with an anti-SIGNR1 antibody. LPS-induced secretion of IL-6 from RAW-SIGNR1 cells was also clearly inhibited by treatment of the cells with OMLs >0.4µm in diameter, but treatment with OMLs <0.4µm in diameter did not affect the IL-6 secretion. In contrast, LPS-induced TNF-α secretion from the cells was not affected on treatment of the cells with OMLs. Suppression of the IL-6 secretion was not observed following treatment with oligomannose-containing soluble polymers or when cells were bound to an oligomannose-coated solid phase. Phagocytosis of oligomannose-coated liposomes did not interfere with the transcription of IL-6 mRNA, but did affect IL-6 mRNA stability, leading to suppression of IL-6 secretion. Interestingly, treatment of the cells with Ly290042, a PI3 kinase inhibitor, partly blocked the suppression of LPS-induced secretion of IL-6 by OML. Thus, we conclude that SIGNR1-mediated phagocytosis but not SIGNR1-mediated endocytosis and cell adhesion, suppresses the TLR4-mediated production of specific proinflammatory cytokines via PI3 kinase signaling.

Conditional ablation of CD205+ conventional dendritic cells impacts the regulation of T-cell immunity and homeostasis in vivo.

Dendritic cells (DCs) are composed of multiple subsets that play a dual role in inducing immunity and tolerance. However, it is unclear how CD205(+) conventional DCs (cDCs) control immune responses in vivo. Here we generated knock-in mice with the selective conditional ablation of CD205(+) cDCs. CD205(+) cDCs contributed to antigen-specific priming of CD4(+) T cells under steady-state conditions, whereas they were dispensable for antigen-specific CD4(+) T-cell responses under inflammatory conditions. In contrast, CD205(+) cDCs were required for antigen-specific priming of CD8(+) T cells to generate cytotoxic T lymphocytes (CTLs) mediated through cross-presentation. Although CD205(+) cDCs were involved in the thymic generation of CD4(+) regulatory T cells (Tregs), they maintained the homeostasis of CD4(+) Tregs and CD4(+) effector T cells in peripheral and mucosal tissues. On the other hand, CD205(+) cDCs were involved in the inflammation triggered by Toll-like receptor ligand as well as bacterial and viral infections. Upon microbial infections, CD205(+) cDCs contributed to the cross-priming of CD8(+) T cells for generating antimicrobial CTLs to efficiently eliminate pathogens, whereas they suppressed antimicrobial CD4(+) T-cell responses. Thus, these findings reveal a critical role for CD205(+) cDCs in the regulation of T-cell immunity and homeostasis in vivo.

A SAXS and USAXS study of the influence of pH on the casein micelle structure.

Changes in milk pH significantly influence the behavior and physical properties of casein micelles; however, the effects of these changes on casein micelle structures are still unclear. The aim of this study was to elucidate the effect of changes in pH range from 5.9 to 7.1 on the structure of casein micelles in milk using small-angle X-ray scattering (SAXS) and ultra small-angle X-ray scattering (USAXS). The casein micelles formed one-dimensional aggregates. The micelle radius decreased with decreasing pH, whereas the size of the water domain increased. The distance between colloidal calcium phosphates (CCP) remained unchanged, whereas the CCP radius decreased with decreasing pH. Voluminosity, which was calculated from scattering intensities, increased at increased pH. In conclusion, the micelle structure changed significantly in response to changes in pH. Our findings help to understand the changes in the physical properties of milk at various pH levels in terms of the microscopic structure.

Magnetic Supramolecular Spherical Arrays: Direct Formation of Micellar Cubic Mesophase by Lanthanide Metallomesogens with 7-Coordination Geometry.

Here, an unprecedented phenomenon in which 7-coordinate lanthanide metallomesogens, which align via hydrogen bonds mediated by coordinated H2O molecules, form micellar cubic mesophases at room temperature, creating body-centered cubic (BCC)-type supramolecular spherical arrays, is reported. The results of experiments and molecular dynamics simulations reveal that spherical assemblies of three complexes surrounded by an amorphous alkyl domain spontaneously align in an energetically stable orientation to form the BCC structure. This phenomenon differs greatly from the conventional self-assembling behavior of 6-coordinated metallomesogens, which form columnar assemblies due to strong intermolecular interactions. Since the magnetic and luminescent properties of different lanthanides vary, adding arbitrary functions to spherical arrays is possible by selecting suitable lanthanides to be used. The method developed in this study using 7-coordinate lanthanide metallomesogens as building blocks is expected to lead to the rational development of micellar cubic mesophases.