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A copper-catalyzed asymmetric vinylogous conjugate addition of butenolide to 2-ester-substituted chromones is described, and it delivers syn- or anti-chromanone lactones with high stereoselectivities. The enantioselectivity-determining step varied with the use of B(OMe)3as an additive, resulting in enhanced stereoselectivities, as revealed by density functional theory calculations, which also provided theoretical insight into the origin of the ligand-dependent diastereodivergence.

Although many investigations of thermoresponsive microgels have been reported, their surface properties, which are crucial in colloid science, are still not fully understood. In this study, microgels with surface-localized charged groups were synthesized by precipitation polymerization, and their electrophoretic behaviors were analyzed using a modified version of Ohshima’s equation to obtain two surface properties of the soft particles: the softness parameter and the surface charge density. This systematic evaluation allows us to discuss the thermoresponsiveness of the overall microgels and their surfaces separately. Furthermore, the validity of the surface properties obtained from electrophoresis was verified by comparing them with the results of seeded emulsion polymerization in the presence of the microgels and the force–indentation curves obtained via high-speed atomic force microscopy (HS-AFM).

Selective modulation of autophagy is a promising therapeutic strategy, especially for cancer treatment. However, the lack of specific autophagy inhibitors limits this strategy. The formation of the ATG12–ATG5–ATG16L1 complex is essential for targeting the ATG12–ATG5 conjugate to proper membranes and to generate LC3-II for the progression of autophagy. Thus, targeting ATG5–ATG16L1 protein–protein interactions (PPIs) might inhibit early stage autophagy with high specificity. In this paper, we report that a stapled peptide derived from ATG16L1 exhibits potent binding affinity to ATG5, striking resistance to proteolysis, and significant autophagy inhibition activities in cells.

The excited-state intramolecular proton transfer (ESIPT) of 4′-N,N-dialkylamino-3-hydroxyflavone (CnHF) having different alkyl chain lengths (ethyl, butyl, and octyl chains) was investigated in ionic liquids (ILs) by steady-state fluorescence and transient absorption spectroscopy. Upon photoexcitation, CnHF underwent ESIPT from the normal form to the tautomer form, and dual emissions from both states were detected. For C4HF and C8HF, the tautomerization yields determined from the fluorescence intensity ratios increased with the increasing number of alkyl chain carbon atoms in the cation and on reducing the excitation wavelength as reported for C2HF [K. Suda et al., J. Phys. Chem. B. 117, 12567 (2013)]. The transient absorption spectra of CnHF were measured at excitation wavelengths of 360, 400, and 450 nm. The ESIPT rate determined from the induced emission of the tautomer was correlated with the tautomerization yield for C2HF and C4HF. In addition, the recovery of the ground-state bleach was found to be strongly dependent on the excitation wavelength. This result indicates that the solvated state of the molecule before photoexcitation is dependent on the excitation wavelengths. The time constant for the ground-state relaxation was slower than that for the excited state.

Postcore flood analysis was conducted on a tertiary-mode CO2flooding test under reservoir conditions. A composite carbonate core was retrieved to extract remaining hydrocarbons via Dean-stark distillation, and asphaltenes were measured in the extracted oil from each plug core using the IP-143 method. The analysis revealed uneven variation of asphaltene mass along plug cores: more asphaltenes were collected from the inlet-side core. To understand the mechanism of uneven in situ asphaltene-deposition, two numerical models were adopted that were based on thermodynamic and three-dimensional geological porous transport. The outcomes of thermodynamic modeling, using a cubic-plus-association model to estimate asphaltene precipitation as a function of CO2concentration, proposed a scenario causing the uneven asphaltene distribution by incorporating vaporizing-gas-drive (VGD) into an asphaltene-destabilizing mechanism. This means more asphaltene deposition was predominantly caused when purer CO2was in contact with fresh reservoir oil. The vaporized intermediate hydrocarbons in front, extracted through VGD, might dilute the injected CO2concentration in the gas phase. This briefly caused the CO2concentration to be higher in the inlet-side cores and lower in the outlet-side cores. Using a micro-CT scanned core, a 3D geological transport model was generated to estimate in-depth penetration of asphaltene particles in porous media. Three particle sizes (0.59–17.6 μm) were modeled as per visual inspection of destabilized asphaltene particles/aggregates that grew as oil was mixed with higher CO2concentration (average particle diameters of 2.5, 3.6, and 17.6 μm for 0, 20, and 40 mol % CO2addition). The setting of model particle sizes also considered the pore throat size distribution of the 3D geological transport model. The 3D transport model results propose a subsequent scenario in which smaller asphaltene spheres penetrate more deeply in porous media.

The Belousov–Zhabotinsky (BZ) reaction shows temporal or spatiotemporal structures such as redox oscillation of the catalyst, [ruthenium(II)tris(2,2′-bipyridine)][PF6]2([Ru(bpy)3][PF6]2). In this study, autonomously oscillating hydrogel microspheres (microgels) were investigated, which show swelling/deswelling oscillation induced by the redox oscillation of the BZ reaction inside the gel. Despite the periodically and autonomously induced oscillation that does not require an external stimulus, it has not been possible to perform any manipulation of the oscillatory behavior over time. The results of the present study show that it is possible to reversibly switch the microgel oscillations from an “on” active state of the BZ reaction to an “off” inactive state by changing the temperature in combination with thermoresponsive microgels. To realize on-demand switching, the construction of double-shell structures is crucial; the thermoresponsive first shell allows the microgels to modulate the diffusion of the substrates or intermediates in the BZ reaction, while the second shell maintains colloidal stability under high temperatures and high ion concentrations. The functionalized double-shell microgels were prepared via multistep seeded precipitation polymerization. The oscillatory switching behavior of the BZ reaction was observed directly and evaluated by ultraviolet–visible (UV–vis) spectroscopy. The central concept of this study, i.e., “on–off switching” can be expected to benefit the development of advanced bioinspired materials.

In a series of isothermal depressurizing tests to measure asphaltene onset pressure (AOP), several depressurizing operations are usually conducted to multiple AOPs using the same lot of fluid subsamples. After one depressurizing operation is finished, the pressure/temperature condition is reset to the initial condition. Then, the next depressurizing run is performed. Before the next run, the fluid sample must equilibrate again by dissolving precipitated asphaltenes from the previous step. According to our many experiences with isothermal depressurizing tests for measuring AOPs, we know that redissolving asphaltenes depends highly upon the characteristics of a fluid sample. Some fluids redissolve asphaltenes quickly, while other samples need a lot of time. This study focused on fluid-dependent asphaltene re-equilibrium during a series of isothermal depressurizing tests. To investigate asphaltene re-equilibrium, the authors re-examined past experimental data for two types of crude oils. In the experiment, continuous power of light transmittance (PLT) was monitored for all stages in the series of AOP measurements. Two series of isothermal depressurizing tests were separately performed to evaluate CO2-induced asphaltene risks for two fluid samples. Three or four total steps of depressurizing were conducted in order of CO2addition ratios: 0, 20, 40, and 60 mol %. After a depressurizing process finished, pressure was increased above AOP to dissolve precipitated asphaltenes. PLT profiles in equilibrium steps between each depressurizing step were compared from a viewpoint of equilibrium time and/or PLT profile fluctuation. One of the fluids showed quick re-equilibrium of asphaltenes and smooth PLT profiles, whereas the other took much longer to achieve equilibrium and had fluctuating PLT profiles. This information suggested that easy-equilibrium-achievable fluids would be a preferred target for CO2enhanced oil recovery because of its potential use of pressure control for mitigating asphaltenes. In the case of easy-equilibrium-achievable fluid, when a production problem is caused by asphaltene precipitation, repressurization by temporary shut-in and/or production rate control can be an effective mitigation.

The development of a green and facile method for the controlled synthesis of functional polypeptides is desired for sustainable material applications. In this study, the regioselective synthesis of poly(l-lysine) (polyLys) via enzyme-catalyzed aminolysis was achieved by bulk polymerization of l-lysine ethyl ester (Lys-OEt) using immobilized Candida antarcticalipase Novozym 435 (IM-lipase) or trypsin (IM-trypsin). Structural characterization of the obtained polyLys revealed that IM-lipase resulted solely in ε-linked amide bond formation, whereas IM-trypsin predominantly provided α-linked polyLys. Optimization of the conditions for the bulk polymerization using immobilized enzymes resulted in high monomer conversion and a high degree of polymerization, with excellent regioselectivity. Molecular docking simulations revealed different binding conformations of Lys-OEt to the catalytic pockets of lipase and trypsin, which putatively resulted in different amino moieties being used for amide bond formation. The immobilized enzymes were recovered and recycled for bulk polymerization, and the initial activity was maintained in the case of IM-trypsin. The obtained α- and ε-linked polyLys products exhibited different degradability against proteolysis, demonstrating the possibility of versatile applications as sustainable materials. This enzymatic regioregular control enabled the synthesis of well-defined polypeptide-based materials with a diverging structural variety.

Domains in a crystal, which have crystallographic uniformity and are geometrically segmented, typically arise from various phase transitions. The physical properties within individual domains are inherently the same as those in the homogeneous bulk. As a result, sufficiently large domains have little influence on the bulk properties. However, as the domains decrease in size to the nanoscale, for instance, due to multiple phase instabilities or spatial inhomogeneities, then the materials often acquire exceptional functionalities that are unattainable without these domains. This effect is exemplified by the ultrahigh dielectric and piezoelectric responses observed in ferroelectric oxides with nanoscale polar domains as well as in ferroelectric relaxors with polar nanoclusters. Here, we demonstrate that hashed nanoscale domains in an antiferroelectric material are also capable of boosting dielectric permittivity in an unconventional way. This discovery has been made in an antiferroelectric titanite-type oxide, CaTi(Si1–xGex)O5, in which the permittivity significantly increases when the antiferroelectric order becomes short-range. Our transmission electron microscopy observations have clarified that polar regions simultaneously appear around antiphase boundaries in the antiferroelectric phase of CaTi(Si1–xGex)O5. As the concentration of the antiphase boundary increases, the polar regions become denser and play a crucial role in boosting the permittivity. At the composition of x= 0.5, the value of the permittivity finally reaches double that in the bulk and shows excellent linearity, at least until an electric field of 500 kV/cm is applied. The present findings highlight the promise of domain engineering for boosting the permittivity in antiferroelectrics as a way to develop materials with excellent dielectric properties.

The first enantioselective copper-catalyzed conjugate addition of α-substituted benzyl nitriles to alkyl acrylates is described. This protocol allows the direct and 100% atom-economic generation of a nitrile-containing quaternary stereogenic center in a highly enantioselective manner. The practical application of our methodology was demonstrated through the concise formal synthesis of (−)-aphanorphine.

Polymer-based lubricant additives for friction reduction, wear protection, or viscosity improvement have been widely studied. However, single additives achieving all three functions are rare. To address this need, we have explored the combination of polymer topology with organic–inorganic hybrid chemistry to simultaneously vary the temperature- and shear-dependent properties of polymer additives in solution and at solid surfaces. A topological library of lubricant additives, based on statistical copolymers of stearyl methacrylate and methyl methacrylate, ranging from linear to branched star architectures, was prepared using ruthenium-catalyzed controlled radical polymerization. Control over the polymerization yielded additives with low dispersity and comparable molecular weights, allowing evaluation of the influence of polymer architecture on friction reduction, wear protection, and bulk viscosity improvement in a commercial base oil (Yubase 4). Structure–performance relationships for these functions were assessed by a combination of a high-speed surface force apparatus (HS-SFA) experiments, wear track profilometry, quartz crystal microbalance analysis, and solution viscometry. The custom-built HS-SFA provides a unique experimental environment to measure the boundary lubrication performance under extreme shear rates (≈107s–1) for prolonged times (24 h), mimicking the extreme conditions of automotive applications. These experiments revealed that the performance of the additives as boundary lubricants and wear protectants scales with the degree of branching. The branched architectures prohibit ordering of the additives in thin films under high-load conditions, leading to a thicker absorbed polymer brush boundary layer and therefore enhanced film fluidity and lubricity. Additionally, star polymers with increasing arm number lead to bulk viscosity modification, reflected by a significant increase in the viscosity index compared to the commercial base oil. Although outperformed by linear polymers for bulk viscosity improvement, the (hybrid) star polymers successfully combine the three distinct lubricant additive functions: friction reduction, wear protection, and bulk viscosity improvement—in a single polymeric structure. It should also be noted that, judging from HS-SFA experiments, hybrid stars carrying a silicate-based core outperform their fully organic analogues as boundary lubricants. The enhanced performance is most likely driven by attractive forces between the silicate cores and the employed metallic surfaces. Combining three function in one minimizes formulation complexity and thus opens a route to fundamentally understand and formulate key design parameters for the development of novel multifunction lubricant additives.

Densely packed soft microgels (pastes) behave as a yield-stress fluid. They act as soft elastic solids with finite equilibrium shear modulus (G0) below a critical stress (σc) whereas they flow like liquids above σc. The effects of size and stiffness heterogeneities in the constituent microgels on the rheological properties of the pastes are revealed using the binary microgel mixtures by an oscillatory rheometer and diffusive wave spectroscopy (DWS). The binary blends with various degrees of size and stiffness disparities are made by mixing the pastes with the same apparent particle-volume fraction (ϕeff) at various values of relative weight fraction of soft microgels (fsoft). The G0–fsoftrelations for the soft/hard microgel mixtures are significantly influenced by size disparity: The relations for small size disparities well obey the logarithmic mixing rule, while those for large size disparities have a wide fsoftregime in which G0are almost equal to those of the single small-microgel pastes (G0,small), regardless of whether the small microgels are soft or hard. The characteristic fsoftregion with G0≈ G0,smallfor the mixtures with large size disparities is attributed to the developed continuous phase of small microgels (overwhelming in number) where the large microgels are discretely dispersed. The steady-state flow behavior of the binary pastes above σcobey the classical Hershel–Bulkley (H–B) equation. In each binary paste, the characteristic time (τcage) of the fast local dynamics of microgels trapped in the densely packed structures evaluated from DWS is close to the characteristic time (τHB) obtained from the parameters in the H–B equation and G0. This agreement shows that the dynamics of the positional rearrangement of microgels in the steady-state flow is closely related to the fast local dynamics in the quiescent state of the pastes, independently of the size and stiffness disparities in the constituent microgels.

Perovskites have been attracting attention because of their considerable luminescence properties. A conventional perovskite such as BaTiO3has no intrinsic photoluminescence. Doping with rare metals, nanocrystallization, and addition of organometallic halides induce significant photoluminescence and photovoltages. Here, we report anomalous light reflection and photoluminescence of BaTiO3on heating. Light absorption shifted from the near-ultraviolet region to the visible region on heating. The small emission peaks at around 400–500 nm disappeared and new peaks appeared above 800 nm; the quantum yields of these peaks were less than 1% and more than 7%, respectively.

In a previous study, we have ascertained that the charge distribution in hydrogel microspheres (microgels) plays a crucial role in controlling the nanocomposite structure of the polystyrene obtained from the seeded emulsion polymerization (SEP) of styrene in the presence of microgels. However, all these polymerizations were conducted at high temperature, where most of these microgels were dehydrated and deswollen. In the present study, we initially verified that the nanocomposite microgels can be synthesized even when the seed microgels are swollen and hydrated during the SEP of styrene. These highly swollen microgels were used as the nucleation sites for the polystyrene, and subsequently the propagation of the hydrophobic polystyrenes proceeded within water-swollen microgels.

Hydrogel microspheres (microgels), which consist of crosslinked hydrophilic or amphiphilic polymer chains, are components of stable colloidal dispersions. Their typical size is below ~10 μm, and they exhibit fascinating properties in aqueous solution. Owing to their attractive properties, they have been used for a variety of applications (for example, as templates, sensors, catalysts, and coatings) and have promising prospects for advanced chemical technologies such as drug carriers. In this context, we have been conducting research on microgels, including their synthesis, characterization, assembly, and application. In this focus review, we summarize recent results of microgel research conducted mainly by our group as well as work by our collaborators.

Butyrolactones are prevalent structural elements in many natural products. Vinylogous conjugate additions of butenolides are among the most promising synthetic methods for generating natural products and/or natural product‐like compounds with potential biological activities. In this report, direct 1,6‐conjugate addition of butenolide to p‐quinone methides via Brønsted base catalysis was performed, which provides an efficient route to interesting molecules. The reaction proceeds with a regioselective γ‐attack of butenolide and shows good functional group tolerance. A direct 1,6‐conjugate additionof butenolide to p‐quinone methides catalyzed by Barton's base was developed, providing an efficient route to some functionalized molecules. The reaction proceeds with a regioselective γ‐attack of butenolide and shows good functional group tolerance.

The rheological properties of suspensions of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) microgels are investigated in the swollen and collapsed states using oscillatory and long-time creep measurements. In the swollen state with repulsive interparticle interaction, the zero shear viscosity and quasi-plateau modulus are solely governed by the effective volume fraction (feff) and are independent of temperature, particle diameter and particle concentration. The long-time creep tests reveal that in the collapsed state with attractive interparticle interactions, the moderately concentrated suspensions with feff˜0.5 become viscoelastic liquids with high viscosities of >105?Pas and long-terminal relaxation times of >103?s due to the formation of a network-like aggregation of particles, whereas the suspensions with the same feffin the swollen state exhibit a Newtonian flow with low viscosities of less than 10-1?Pas. The network-like aggregation of particles is so fragile that it can be broken by a very small stress of several Pascals. The modulus and viscosity in the collapsed state depend on both feffand temperature: the modulus and viscosity increase, as the temperature increases due to an increase in the hydrophobic nature of the PNIPAM chains, which govern the attractive interparticle interaction. The particle aggregations in the collapsed state considerably lower the threshold value of feff(fc), above which the infinite percolation clusters are formed, as compared with the values of fcin the swollen state and for the random close packing of hard spheres.

This study obtained highly uniform and efficient GaN-based vertical-cavity surface-emitting lasers with curved mirrors from a single wafer. The average threshold current (Ith) and the optical output power (Pmax) of 14 chips measured up to 7.0 mA were 0.64 mA and 4.5 mW, respectively. The standard deviations of Ithand Pmaxwere 6.7% and 5.1%, respectively. Additionally, the best chip showed maximum values of wall plug efficiency and output power of 13.4% and 7.6 mW, respectively, at 5.2 mA and 12.8 mA operating currents.

A gram-scale syn-selective asymmetric vinylogous addition of butenolides to chromones, catalyzed by an Al-Li-BINOL (ALB) complex, was developed in this study. For various combinations of substrates, the observed diastereoselectivity approached 20:1 with 84–98% ee. This protocol is complementary to previously reported ones and improves the selectivity for several chromones. This methodology can be applied to a quinolone substrate, affording another type of heterocyclic scaffolds substituted with five-membered lactones. Computational studies support the role of ALB as a bifunctional catalyst in this reaction and provide insights into the origin of the observed stereoselectivity.

Although thin elastomer films of polymer nanoparticles are regarded as environmentally friendly materials, the low mechanical strength of the films limits their use in various applications. In the present study, we investigated the fracture resistance of latex films composed of acrylic nanoparticles where a small quantity of a rotaxane crosslinker was introduced. In contrast to conventional nanoparticle-based elastomers, the latex films composed of the rotaxane-crosslinked nanoparticles exhibited unusual crack propagation behavior; the direction of crack propagation changed from a direction parallel to the crack to one perpendicular to the crack, resulting in an increase in tear resistance. These findings will help to broaden the scope of design of new types of tough polymers composed of environmentally friendly polymer nanoparticles.

TiO2anatase, which exhibits the highest catalytic performance, transforms to rutile at 800 K. To inhibit the transition of anatase to rutile, several strategies, such as metal and/or non-metal doping, oxygen enrichment, and surface coating, have been studied, resulting in stable anatase within 773–1273 K. However, highly stable anatase without dopants is still required. Here, a new approach, which involves the synthesis of anatase nanocatalysts in carbon nanotubes (CNTs), was proposed to inhibit the anatase-to-rutile transition. The nanocatalysts exhibited high thermal anatase stability along with a suppression of the crystal growth up to 1200 K. The highly stable anatase in CNTs also exhibited high photocatalytic activity, which was evaluated based on methylene blue decomposition under visible- and UV-light irradiation. This was attributed to the maintenance of the small crystal size of the nanocatalysts in addition to a synergetic effect between the TiO2nanocatalysts and CNTs.

Quinofuracins A–E, novel anthraquinone derivatives containing β-d-galactofuranose that were isolated from the fungus Staphylotrichum boninensePF1444, induced p53-dependent cell death in human tumor cells. The structures of quinofuracins A–E, including absolute configurations, were elucidated by extensive spectroscopic analysis and chemical transformation studies. Quinofuracins were classified into three groups according to the aglycone moieties. 5′-Oxoaverantin was present in quinofuracins A–C, whereas averantin and versicolorin B were identified in quinofuracins D and E, respectively. These quinofuracins induced p53-dependent growth suppression in human glioblastoma LNZTA3 cells.

t is well known as an important merit of the explosive forming process that the delicate figure of the die surface is precisely transferred onto the specimen of a thin metal plate, because the plate is strongly pressed against the die by the very high pressure of underwater shock wave. However, we cannot find any examples of work pieces making the best use of the merit in literatures until now. We tried to form explosively a thin copper plate into shapes of a palm and a back of human hand, as a work piece making the best use of the merit. The palm has many small delicate lines such as fingerprints and the back has interesting figures such as loose skin at the joints of fingers and the borders of fingernails. The object of the present investigation is to make work pieces just like to a real hand. In this investigation, the following process is adopted in order to perform successfully explosive forming ; real hand plaster concave model convex model of Duplicone (material for dental impression) die of Ren Cast (a kind of epoxy resin) explosive forming. Annealed copper plates of 0.3 mm thick were used in the experiments. Since the extension limit of the plate is not so large, the plate is apt to be broken. If the plate is broken, the die is modified not to break the plate. Though the die made of epoxy resin is too hard to be modified, the plaster model can be easily modified with a cutter knife or a chisel. The modified die is obtained through model of Duplicone made by using the modified plaster model. After a few times of repeating modification, the breakage of plate was scarcely produced. On the work piece of palm, a lot of small lines including finger prints clearly appeared and the work piece of the back showed the shape just like to real human hand.