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We report the syntheses of novel marine biodegradable poly(ethylene succinate) (PES)- and poly(butylene succinate) (PBS)-based copolymers containing different dicarboxylic acid (DCA) units with various carbon numbers and different feed ratios. Biochemical oxygen demand tests demonstrated that some of the obtained PES- and PBS-based copolymers were biodegradable in seawater. Specifically, polymers with longer-chain DCA units, even at low contents, exhibited marine biodegradability. The thermomechanical properties of the copolymers, such as their thermal stabilities, melting points, glass transition temperatures, tensile moduli, strains at break, and stresses at break, also varied with the DCA contents. These results indicated that the thermomechanical properties and the marine biodegradabilities of the PES- and PBS-based copolymers were regulated by controlling their structures and DCA contents. The polymers obtained in this study may replace general-purpose polymers. Our approach may also be applicable to other polymeric materials. Furthermore, our findings pave the way for the rational design and preparation of polymeric materials that are biodegradable in environments other than oceans and have good thermomechanical properties.

Cerium oxide-supported palladium nanoparticles (Pd/CeO2) are poorly active toward the remediation of lean-burn exhausts at a “cold start” (operation temperature <300 °C) due to the presence of excessive palladium oxide (PdO) over the surface. Pd/CeO2was prepared by the wetness-impregnation method and subjected to a gas stream of methane (CH4) and oxygen (O2) at 230 °C. The supported Pd nanoparticles were partly converted to palladium carbide (PdCx) due to carbon doping during this atmosphere treatment. This atmosphere-treated Pd/CeO2material exhibited improved catalytic performance towards remediation of a simulated lean-burn exhaust containing CH4and excessive O2. Comprehensive characterization (scanning transmission electron microscopy, X-ray photoemission spectroscopy, thermogravimetry analysis/differential thermal analysis) of the material demonstrated that the improved catalytic performance of atmosphere-treated Pd/CeO2could be attributed to the oxidative decomposition of PdCxspecies during catalysis, which created surface Pd sites to promote remediation of the lean-burn exhaust at <300 °C.

Molecular hydrogen (H2) ortho‐para conversion (O/P conversion) proceeds slowly at low temperatures accompanying a heat release. Thus, catalysts for accelerating this conversion rate are highly demanded in terms of the storage and utilization of liquid H2. The catalysts for this purpose are experimentally screened by examining a broad range of materials covering magnetic, non‐magnetic, metallic, and nonmetallic oxides. The primary conclusions obtained are summarized below. (1) active materials are required to be non‐metallic and to bear the cations with ionic radii smaller than the bond length of H2. (2) Metallic materials have almost no activity irrespective of with or without magnetism (3) The activity of materials belonging to (1) is largely enhanced when the constituting cation has a magnetic moment. In addition, there is a class of materials for which the activity is distinctly enhanced just upon substitution by the foreign ions. The catalysts for nuclear spin conversion of molecular hydrogen (ortho‐para H2conversion), are categorized into four groups in the ascending order of activity at 77 K; Group 1: metallic materials and most of the oxides containing low‐valence metal cations; Groups 2 and 3: metal oxides comprising high‐valence cations; Group 4: metal oxides and hydroxides that consist of magnetic metal cations.

The photocatalytic dry reforming of methane (photoDRM: CH4 + CO2 = 2CO + 2H2) converts greenhouse gases into valuable synthesis gas with photon energy. However, previous photoDRM catalysts comprising supported metal nanoparticles hardly avoid the recombination of photoexcited charges. Herein, we report that significant photoDRM performance can be achieved by a metal-oxide nanocomposite consisting of nanometer-thick, intertwined networks of fibrous rhodium metal and cerium dioxide, i.e., Rh#CeO2. The Rh#CeO2nanocomposite exhibits the world-highest conversion and yield in photoDRM under UV light irradiation, being accompanied with no other side reactions such as reverse water gas shift reaction. Theoretical simulations and Kelvin probe force microscopy demonstrate that the photoexcited electrons and holes in Rh#CeO2are efficiently partitioned into the Rh- and CeO2nanophases, respectively. The efficient charge partitioning in Rh#CeO2accounts for the selective photoDRM reaction.

Novel polyhydroxyalkanoate (PHA) copolymers of (2R,3R)-3-hydroxy-2-methylbutyrate (3H2MB) and (R)-3-hydroxybutyrate (3HB) [P(3H2MB-co-3HB)] with various comonomer compositions were biosynthesized using recombinant Escherichia coliLSBJ. Furthermore, solvent fractionation of biosynthesized P(24 mol% 3H2MB-co-3HB) was performed to obtain copolymers with narrow comonomer-unit compositional distributions. The melting temperature (Tm) of P(3H2MB-co-3HB) as a function of the comonomer content indicated isodimorphism of the copolymer. The fast crystallization behavior of P(3H2MB) was maintained even when it was copolymerized with 3HB. The P(80 mol% 3H2MB-co-3HB) copolymer, with a Tmclose to that of P(3HB), exhibited faster crystallization behavior than the P(3HB) homopolymer. Therefore, copolymerization of 3H2MB and 3HB is valuable for the design of new PHA materials with desirable properties.

Various copolymers incorporated with β-substituted acrylates, such as alkyl crotonates (e.g., methyl crotonate (MC), ethyl crotonate (EC), isopropyl crotonate (iPC), and n-butyl crotonate (nBC)) and methyl cinnamate (MCin), were synthesized by group-transfer polymerization (GTP) using a silicon-based Lewis acid catalyst. In addition to β-substituted acrylates, α-substituted acrylates (e.g., methyl methacrylate (MMA) and n-butyl methacrylate (nBMA)) were examined as comonomers. Proton nuclear magnetic resonance (1H NMR) spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) characterizations of the obtained copolymers revealed that each monomer component was incorporated sufficiently. The thermal stabilities of the resulting copolymers were investigated by dynamic mechanical analysis (DMA), indicating that the glass-transition temperature (Tg) of the copolymers can be widely varied over a relatively high-temperature range by selecting the optimal comonomer. More specifically, the Tgvalues of poly(MC-random-EC) (MC/EC molar ratio = 50/50), poly(MC-random-nBC) (MC/nBC molar ratio = 50/50), poly(MC-random-MCin) (MC/MCin molar ratio = 54/46), and poly(nBC-random-MCin) (nBC/MCin molar ratio = 56/44) were 173, 130, 216, and 167 °C, respectively.

Poly(ethyl crotonate)s (PECs), possessing various disyndiotacticities, were synthesized by group-transfer polymerization using several silicon Lewis acid catalysts like N-(trialkylsilyl)bis(trifluoromethanesulfonyl)imides (trialkylsilyl = trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, and triisopropylsilyl) and silyl ketene acetals with a corresponding trialkylsilyl moiety as an initiator. Disyndiotacticity of PECs was greatly enhanced by steric hindrance from the silyl moiety of the catalyst and initiator and also by low polymerization temperature. Dynamic mechanical analysis of the obtained PECs revealed that high disyndiotacticity improves heat resistance. The glass transition temperature (Tg) measured by DMA was 201 °C at 92% disyndiotacticity and 82 °C at 53% disyndiotacticity. The Tgenhancement at high tacticity was sufficiently large when compared to syndiotactic poly(methyl methacrylate). This is attributed to the regular arrangement of polymer chains derived from highly controlled ditacticity, as supported by analysis of polarizing optical micrographs and X-ray diffraction patterns.

The first total synthesis of tricyclic bisnorsesquiterpene paralemnolide A, isolated from the soft coral Paralemnalia thyrsoides, was achieved. This synthesis features the lactonization of the cyclohexene derivative having a tert-butyl ester via stereoselective epoxidation followed by treatment with a Brønsted acid and construction of the novel tricyclic skeleton by an intramolecular Reformatsky–Honda reaction.

Heavy metals are the most hazardous water pollutants, with severe health and environmental consequences. Among these, mercuric (Hg2+) ions are known to cause detrimental health issues in both humans and aquatic life. Due to this, several analytical techniques have been devised to detect and quantify the amount of this ion. However, most of these require advanced instrumentation, prolonged analysis time, and sample preparation. In this study, a low-cost and highly reusable colorimetric probe was developed by grafting porphyrin to poly(ethylene terephthalate) sheets using an oxazoline polymer as covalent adhesive. Upon exposure to trace amounts of Hg2+in solution, the fabricated material visually transitioned from faint brownish pink to green by the complexation mechanism. Additionally, the transparency of this probe allowed the quantitative spectrophotometric determination of the Hg2+concentration in aqueous samples. It was also shown that the material is highly stable, which can be reused for more than 50 times without significant decline in its performance, hence, making it suitable for the onsite monitoring of mercuric ion contamination in different bodies of water.

Various poly(alkyl crotonate)s (PRCrs) were synthesized by group-transfer polymerization (GTP) using organic superacid catalysts such as 1-[bis(trifluoromethanesulfonyl)methyl]-2,3,4,5,6-pentafluorobenzene (C6H5CHTf2) and 1-trimethylsiloxyl-1-methoxy-2-methyl-1-propene (MTS) as an initiator. Under the optimized reaction conditions, the corresponding poly(ethyl crotonate) (PEtCr) was obtained with a narrow molecular weight distribution (MWD = 1.14) in quantitative yield (>99%). The thermal stabilities of the PRCrs obtained by organic acid-catalyzed GTP were generally superior to those of poly(alkyl methacrylate)s. The glass-transition temperature (Tg) of poly(methyl crotonate) (PMeCr) (122 °C) was higher than that of poly(methyl methacrylate) (PMMA) prepared by GTP (104 °C). The 5% weight loss temperature (Td5) of PMeCr (359 °C) was also higher than that of PMMA (304 °C). The values of the total light transmittance (Tt) (reaching 91.9%) and haze (<5%) of the PRCr films were similar to those of both PMMA films and glass plates.

A novel chiral 1,3-diketone possessing C2symmetry was synthesized and utilized in the asymmetric synthesis of guignardone H and I by employing sequential condensation–6π-electrocyclization reactions with the novel 1,3-diketone followed by stereoselective hydrogenation as key steps. Although the synthetic compounds differed from natural guignardone H and I, we realized that the C4-epimers of the proposed structures for guignardone H and I were the actual structures.

A new visible light responsive photocatalyst Sn(ii)-doped SrNb2O6has been developed for water reduction and water oxidation reactions. First-principles calculations revealed that the Sn(ii) dopant created a new occupied state in the band gap which resulted in photocatalytic activities under visible light irradiation.

To study the effects of the main and side chains on the physical properties of polyesters containing anthraquinone substituents, two types of 1,5-dihydroxy-2,3,6,7-tetraalkoxyanthraquinones (DHTAAQs) were prepared from gallic acid, a major component of hydrolyzable tannins, and polymerized with five dicarboxylic dichlorides by interfacial polymerization. The solubility of the fabricated polyesters was strongly affected by the alkoxy side chains of the DHTAAQ units. Conversely, their thermal decomposition behavior depended on the structure of the dicarboxylate units. The thermal properties of the anthraquinone-based polyesters were influenced by both the dicarboxylate units and alkoxy groups, and their glass transition temperature could be controlled over a wide range (81–308 °C). To design DHTAAQ-based polyesters with adequate solubility and high heat resistance, it is preferable that first suitable alkoxy groups are selected to provide the necessary solubility, and then appropriate aromatic dicarboxylate units are chosen to obtain the required thermal properties.

Two polyhydroxyalkanoate (PHA) copolymers, poly(3-hydroxybutyrate-co-3-hydroxy-3-phenylpropioate) [P(3HB-co-3H3PhP)] and poly(3-hydroxybutyrate-co-3-hydroxy-4-phenylbutyrate) [P(3HB-co-3H4PhB)], both bearing aromatic side chains, were biosynthesized by recombinant Ralstonia eutrophafed with a respective precursor for the aromatic unit. As bacterial PHA copolymers generally exhibit broad comonomer compositional distribution, the as-biosynthesized samples, P(3HB-co-18 mol% 3H3PhP) and P(3HB-co-11 mol% 3H4PhB), were fractionated into several fractions with narrow comonomer compositional distribution using a chloroform/n-hexane mixed solvent. When the fractionated samples were aged under ambient conditions, the P(3HB-co-3H3PhP) fraction with 12 mol% 3H3PhP exhibited a melting temperature (Tm) of 132–148 °C, whereas the fractions with 15–21 mol% 3H3PhP did not exhibit melting behavior. As for P(3HB-co-3H4PhB), all fractions with a range of 4–15 mol% 3H4PhB exhibited Tmin the range 105–151 °C. The glass transition temperature (Tg) of these copolymers increased with increasing aromatic unit content, and the highest Tgof 20 °C was observed for the fraction with 21 mol% 3H3PhP. On the basis of the results presented here, the effects of aromatic comonomers on the thermal properties of the resulting copolymers are discussed.

A copper–zirconia composite having an evenly distributed lamellar texture, Cu#ZrO2, was synthesized by promoting nanophase separation of the Cu51Zr14alloy precursor in a mixture of carbon monoxide (CO) and oxygen (O2). High-resolution electron microscopy revealed that the material consists of interchangeable Cu and t-ZrO2phases with an average thickness of 5 nm. Cu#ZrO2exhibited enhanced selectivity toward the generation of formic acid (HCOOH) by electrochemical reduction of carbon dioxide (CO2) in aqueous media at a Faradaic efficiency of 83.5% at −0.9 V versus the reversible hydrogen electrode. In situ Raman spectroscopy has revealed that a bifunctional interplay between the Zr4+sites and the Cu boundary leads to amended reaction selectivity along with a large number of catalytic sites.

Polyhydroxyalkanoates (PHAs), aliphatic polyesters synthesized by microorganisms, have gained considerable attention as biodegradable plastics. Recently, α-carbon-methylated PHAs have been shown to exhibit several interesting properties that differ from those of conventional PHAs, such as their crystallization behavior and material properties. This study investigated α-carbon methylated (S)- and (R)-3-hydroxy-2-methylpropionate (3H2MP) as new repeating units. 3H2MP units were homopolymerized or copolymerized with (R)-3-hydroxybutyrate (3HB) by manipulating the culture conditions of recombinant Escherichia coliLSBJ. Consequently, PHAs with 3H2MP units ranging from 5 to 100 mol % were synthesized by external addition of (R)- and (S)-enantiomers or the racemic form of 3H2MPNa. The (S)-3H2MP precursor supplemented into the culture medium was almost directly polymerized into PHA while maintaining its chirality. Therefore, a highly isotactic P(3H2MP) (R:S= 1:99) was synthesized, which displayed a melting temperature of 114–119 °C and a relatively high enthalpy of fusion (68 J/g). In contrast, in cultures supplemented with (R)-3H2MP, the precursor was racemized and polymerized into PHA, resulting in the synthesis of the amorphous polymer atactic P(3H2MP) (R:S= 40:60). However, racemization was not observed at a low concentration of the (R)-3H2MP precursor, thereby synthesizing P(3HB-co-8 mol % 3H2MP) with 100% (R)-3H2MP units. The thermogravimetric analysis revealed that the thermal degradation temperatures at 5% weight loss of P(3H2MP)s occurred at approximately 313 °C, independent of tacticity, which is substantially higher than that of P(3HB) (257 °C). This study demonstrates a new concept for controlling the physical properties of biosynthesized PHA by manipulating the polymers’ tacticity using 3H2MP units.

Metal/TiO2interfaces have been extensively studied because of their importance in electronic devices, electrochemical cells, and photocatalysis. In this article, we present our studies on electronic structures for anatase TiO2(001)/fcc-metal(001) (metal = Pt, Pd, or Au) interfaces using first-principles calculations. It is demonstrated that the Schottky barrier height depends on the metal work function and significantly decreases at an interface with strong adhesion between the metal and TiO2. The sizable reduction of the barrier height is a consequence of dipole formation at the interface due to electron transfer from TiO2to the metal. The formation of dipoles at the Pt/TiO2interface is supported by our experimental results for a core-level binding-energy shift in Pt clusters loaded on the surface of TiO2. Differences in the bonding and antibonding characters of metal–O bonds for the three metals are discussed based on the projected densities of states given by our density-functional theory calculations.

In this study, we investigated the effect of photo-irradiation on dry reforming of methane (DRM) over several metal oxides. Among these oxides, strontium titanate (SrTiO3) exhibited the largest photo-effect and high stability against coking at ~700 °C. Band-gap excitation of SrTiO3is indispensable for driving efficient DRM. These results indicated that the photon energy could be utilized to promote DRM reaction over SrTiO3.In this study, we investigated the effect of photo-irradiation on dry reforming of methane (DRM) over several metal oxides. SrTiO3exhibited the largest photo-effect and high stability against carbon coking at ~700 °C. Band-gap excitation of SrTiO3is indispensable for driving efficient DRM. These results clearly indicated that the photon energy can be utilized to promote DRM reaction over SrTiO3.

Although compositional tuning of metal nanoparticles (NPs) has been extensively investigated, possible control of the catalytic performance through bulk-structure tuning is surprisingly overlooked. Here we report that the bulk structure of intermetallic ZrPt3NPs can be engineered by controlled annealing and their catalytic performance is significantly enhanced as the result of bulk-structural transformation. Chemical reduction of organometallic precursors yielded the desired ZrPt3NPs with a cubic FCC-type structure (c-ZrPt3NPs). The c-ZrPt3NPs were then transformed to a different phase of ZrPt3with a hexagonal structure (h-ZrPt3NPs) by annealing at temperatures between 900 and 1000 °C. The h-ZrPt3NPs exhibited higher catalytic activity and long-term stability than either the c-ZrPt3NPs or commercial Pt/C NPs toward the electro-oxidation of ethanol. Theoretical calculations have elucidated that the enhanced activity of the h-ZrPt3NPs is attributed to the increased surface energy, whereas the stability of the catalyst is retained by the lowered bulk-free-energy.

A mixed-valence tin oxide, (Sn2+)2(Sn4+)O4, was synthesized via a hydrothermal route. The Sn3O4material consisted of highly crystalline {110} flexes. The Sn3O4material, when pure platinum (Pt) was used as a co-catalyst, significantly catalyzed water-splitting in aqueous solution under illumination of visible light (λ > 400 nm), whereas neither Sn2+O nor Sn4+O2was active toward the reaction. Theoretical calculations have demonstrated that the co-existence of Sn2+and Sn4+in Sn3O4leads to a desirable band structure for photocatalytic hydrogen evolution from water solution. Sn3O4has great potential as an abundant, cheap, and environmentally benign solar-energy conversion catalyst.

The long-term, stable, and improved electrocatalytic performance towards the oxygen reduction reaction (ORR) has been achieved by anatase-type titania (TiO2)-supported PtPb nanoparticles (NPs). Organometallic precursors, H2PtCl6·6H2O and Pb(CH3COO)2were co-reduced using sodium borohydride at ambient temperature to precipitate the PtPb NPs (NiAs-type structure, P63/mmc, a= 0.4259 nm; c= 0.5267 nm, average particle size: 3 nm) over the TiO2support (PtPb/TiO2). PtPb/TiO2showed substantial electrocatalytic activity towards ORR both in terms of the onset potential and the mass activity compared to TiO2-supported Pt NPs (Pt/TiO2). The onset potential of PtPb/TiO2was shifted to a higher electric potential by 180 mV compared to Pt/TiO2. Also, PtPb/TiO2showed a seven-times higher ORR mass activity than Pt/TiO2. Neither the onset potential nor the mass activity of PtPb/TiO2was altered after ORR cycles, whereas those of commercially available Vulcan carbon-supported Pt NPs (Pt/VC; Pt loading: 20 wt%) were largely altered. The PtPb NPs were not agglomerated over the TiO2support even after repeated cycles under the electric potential condition, as the result of the strong interactions between the PtPb NPs and the TiO2support, but the Pt NPs were significantly agglomerated over the TiO2- and the Vulcan carbon-supports due to the weak interactions between the Pt NPs and the supports. PtPb/TiO2can be a practical cathode material for direct fuel cells in terms of its long-term stability and enhanced catalytic performance.

Nanostructured novel Pt/Clay nanocomposites consisting of well-defined Pt nanoparticles prepared by clay-mediated in situ reduction displays very high thermal stability, large BET surface area and superior catalytic activity for CO oxidation as compared to a model reference Pt/SiO2catalysts. CO oxidation has attracted renewed attention because of its technological importance in the area of pollution control. The Pt/Clay system consisting of Pt nanoparticles strongly immobilized between the atomic layers of clay inhibits nanoparticle sintering and loss of catalytic activity even after prolonged heating at high temperatures. At elevated temperatures (300 °C), the Pt/Clay system demonstrates significant enhancement of catalytic activity, with almost 100% CO conversion in less than 5 min. Emphasis is given to the role played by the clay supporting material which is chemically and thermally stable under the catalytic conditions of exhaust purification.

Methanol is a highly toxic substance, but it is unfortunately very difficult to differentiate from other alcohols (especially ethanol) without performing chemical analyses. Here we report that a composite film prepared from oxoporphyrinogen (OxP) and a layered double hydroxide (LDH) undergoes a visible color change (from magenta to purple) when exposed to methanol, a change that does not occur upon exposure to ethanol. Interestingly, methanol-induced color variation of the OxP-LDH composite film is retained even after removal of methanol under reduced pressure, a condition that does not occur in the case of conventional solvatochromic dyes. The original state of the OxP-LDH composite film could be recovered by rinsing it with tetrahydrofuran (THF), enabling repeated usage of the composite film. The mechanism of color variation, based on solid-state 13C–CP/MAS NMR and solution-state 13C NMR studies, is proposed to be anion transfer from LDH to OxP triggered by methanol exposure.

The synthesis of intermetallic Ni-Al nanoparticles by co-reduction approach of several organometallic precursors with sodium naphthelide in non-aqueous solution was studied. The state of the art in nanoparticles synthesisation is the selection of suitable precursors and the adaption of colloid chemistry to non-aqueous media at the room temperature under inert atmosphere. The reduction of an organometallic precursor, nickel (II) acetylacetonate, Ni(Acac)2 as a source of Ni element of the intermetallic, and aluminum trichloride, AlCl3 in tetrahydrofuran (THF) solution gave a black particles. The powder X-ray diffraction spectroscopy (pXRD) result shows an expansion of lattice parameter for FCC-Ni indicating the cooperation of Al atoms in Ni structures. The estimation value of Al concentration using Scherrer’s equation is 10 at%. The particles were investigated in more detail by hard X-ray photoemission spectroscopy (HX-PES). The HX-PES spectrums confirmed that the black particles has binding energy consistent to standard materials of Ni3Al. The absence of organic residues shown by the Fourier-transform infrared, FTIR spectrometer indicates that the as prepared Ni-Al nanoparticles are free from by-products.

There have been only a few reports on follow-up results of serous cystic neoplasm (SCN) of the pancreas. The frequency of malignancy and surgical indication of SCN are not determined yet.

Liposomes reportedly accumulate in monophagocytic systems (MPSs), such as those of the spleen. Accumulation of considerable amounts of liposome in a MPS can affect immunologic response. While developing a liposomal oxygen carrier containing human hemoglobin vesicle (HbV), we identified its suppressive effect on the proliferation of rat splenic T cells. The aim of this study was to elucidate the mechanism underlying that phenomenon and its effect on both local and systemic immune response. For this study, we infused HbV intravenously at a volume of 20% of whole blood or empty liposomes into rats, removed their spleens, and evaluated T cell responses to concanavalin A (Con A) or keyhole limpet hemocyanin (KLH) by measuring the amount of [(3)H]thymidine incorporated into DNA. Cells that phagocytized liposomal particles were sorted using flow cytometry and analyzed. Serum anti-KLH antibody was measured after immunizing rats with KLH. Results showed that T cell proliferation in response to Con A or KLH was inhibited from 6 h to 3 days after the liposome injection. Direct cell-to-cell contact was necessary for the suppression. Both inducible nitric-oxide synthase and arginase inhibitors restored T cell proliferation to some degree. The suppression abated 7 days later. Cells that trapped vesicles were responsible for the suppression. Most expressed CD11b/c but lacked class II molecules. However, the primary antibody response to KLH was unaffected. We conclude that the phagocytosis of the large load of liposomal particles by rat CD11b/c+, class II immature monocytes temporarily renders them highly immunosuppressive, but the systemic immune response was unaffected.

The aim of this study was to elucidate the clinicopathological features and prognosis of mucinous cystic neoplasms (MCNs).

Surface patterning was carried out by the epitaxial crystallization of biodegradable PCL on a HOPG, and the surface morphologies were observed by atomic force microscopy. Edge‐on view lamellae were aligned along the HOPG lattice to display stripe patterns in the threefold symmetry. The intervals of stripe patterns composed of ridges and valleys increased with an increase in the crystallization temperature. Enzymatic degradation of the PCL nanopattern allowed the different depth profiles of the fringed structure. The persistence length of the nanopattern could be tuned by the molecular weight of PCL.

The bicyclic depsipeptide histone deacetylase (HDAC) inhibitors spiruchostatins A and B, 5′′‐epi‐spiruchostatin B and FK228 were efficiently synthesized in a convergent and unified manner. The synthetic method involved the following crucial steps: i) a Julia–Kocienski olefination of a 1,3‐propanediol‐derived sulfone and a L‐ or D‐malic acid‐derived aldehyde to access the most synthetically challenging unit, (3Sor 3R,4E)‐3‐hydroxy‐7‐mercaptohept‐4‐enoic acid, present in a D‐alanine‐ or D‐valine‐containing segment; ii) a condensation of a D‐valine‐D‐cysteine‐ or D‐allo‐isoleucine‐D‐cysteine‐containing segment with a D‐alanine‐ or D‐valine‐containing segment to directly assemble the corresponding seco‐acids; and iii) a macrocyclization of a seco‐acid using the Shiina method or the Mitsunobu method to construct the requisite 15‐ or 16‐membered macrolactone. The present synthesis has established the C5′′ stereochemistry of spiruchostatin B. In addition, HDAC inhibitory assay and the cell‐growth inhibition analysis of the synthesized depsipeptides determined the order of their potency and revealed some novel aspects of structure–activity relationships. It was also found that unnatural 5′′‐epi‐spiruchostatin B shows extremely high selectivity (ca. 1600‐fold) for class I HDAC1 (IC50=2.4 nM) over class II HDAC6 (IC50=3900 nM) with potent cell‐growth‐inhibitory activity at nanomolar levels of IC50values.

Potential immunosuppressive agents: Candelalides A, B and C (see figure), novel blockers of the voltage‐gated potassium channel Kv1.3, have been efficiently synthesized for the first time in a convergent and unified manner starting from (+)‐5‐methyl‐Wieland–Miescher ketone. The method explored has potential for preparing various types of candelalide analogues for the structure–activity relationship studies.

Given their ubiquity in modern society, the development of biodegradable and renewably sourced plastics is essential for the creation of an environmentally sustainable society. One of the drawbacks for currently available biodegradable plastics such as poly(l-lactic acid) (PLLA) and polyhydroxyalkanoates (PHAs) is that it is difficult to simultaneously achieve mechanical flexibility and certain crystallization behavior in these materials, which limits their use as replacements for established petroleum-based plastics such as isotactic polypropylene (iPP). Here, we report the synthesis and characterization of a new biodegradable plastic, poly(3-hydroxy-2-methylbutyrate) [P(3H2MB)], which is a member of the bacterial PHA family whose members include an α-methylated monomer unit. Biosynthesis of P(3H2MB) was achieved using recombinant Escherichiacoliexpressing an engineered pathway. Biosynthesized P(3H2MB) exhibited the highest melting temperature (197 °C) among the biosynthesized PHAs and improved thermal resistance. It also exhibited improved crystallization behavior and mechanical flexibility nearly equal to those of iPP. The primary nucleation rate of P(3H2MB) was faster than that of P(3HB), and the spherulite morphology of P(3H2MB) was much finer than that of P(3HB). This crystal morphology may result in more rapid crystallization behavior, increased transparency, and enhanced mechanical properties. The superior physical properties of P(3H2MB) have the potential to open new avenues for the production of high-performance biodegradable plastics for replacing petroleum-based bulk commodity plastics.

Biologically important and structurally unique marine natural products avarone (1), avarol (2), neoavarone (3), neoavarol (4) and aureol (5), were efficiently synthesized in a unified manner starting from (+)‐5‐methyl‐Wieland–Miescher ketone 10. The synthesis involved the following crucial steps: i) Sequential BF3⋅Et2O‐induced rearrangement/cyclization reaction of 2and 4to produce 5with complete stereoselectivity in high yield (2→ 5and 4→ 5); ii) strategic salcomine oxidation of the phenolic compounds 6and 8to derive the corresponding quinones 1and 3(6→ 1and 8→ 3); and iii) Birch reductive alkylation of 10with bromide 11to construct the requisite carbon framework 12(10+ 11→ 12). An in vitro cytotoxicity assay of compounds 1–5against human histiocytic lymphoma cells U937 determined the order of cytotoxic potency (3> 1> 5> 2> 4) and some novel aspects of structure‐activity relationships.

Enantioselective total synthesis of (+)‐ottelione A (1) and (−)‐ottelione B (2), novel and potent antitumor agents from a freshwater plant, and (+)‐3‐epi‐ottelione A (3), the earlier proposed stereostructure of 1, was efficiently achieved starting from the known tricyclic compound 10. The synthesis involved the following key steps: i) coupling reactions of aldehydes 8and 9with the aromatic portion 7(8+7→15and 9+7→27), ii) base‐induced hemiacetal‐opening/epimerization reactions of the cyclic hemiacetals 6and 27(6→17and 27 a→26 a), and iii) Corey–Winter's reductive olefination of the cyclic thiocarbonates 21and 36(21→22and 36→37). The present total synthesis fully established the absolute configuration of these natural products. The cell growth inhibition profile, COMPARE analysis, and tubulin inhibitory assay of (+)‐3‐epi‐ottelione A (3) and its O‐acetyl derivative 24demonstrated that these unnatural substances could be prominent lead compounds for the development of anticancer agents with a novel mode of action.

Four novel series of periodic copolymers composed of ester and amide units with the same carbon numbers were synthesized by two-step polycondensation reactions using adipate, linear aliphatic diols, and diamines with various chain lengths, ranging from 3 to 6 methylene groups. Effects of the comonomeric and sequential structures on the physical properties and crystalline structures were investigated for the obtained copolymer series by means of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and tensile testing. The thermal properties of obtained periodic copolymer series were found to be strongly dependent on both comonomeric and sequential structures, and the values showed remarkable differences between neighboring methylene numbers in the comonomer units. Such thermal behavior was strongly correlated to the wide-angle X-ray diffraction patterns, with some copolymers displaying patterns similar to homopolyesters, while other copolymers had diffraction patterns that were very different than the homopolyester, dependent on the comonomeric and sequential structures. These results suggest that the molecular chain arrangements and their intermolecular hydrogen bond interactions based on the ester-amide sequential structure play an important role in the formation of a thermally stable crystalline region. Furthermore, the mechanical properties of periodic copolymers were determined from the stress-strain curves of film samples.

Phase structures and enzymatic degradation of poly(l-lactide) (PLLA)/atactic poly(3-hydroxybutyrate) (ata-PHB) blends with different compositions were characterized by using atomic force microscopy (AFM). Differential scanning calorimetry (DSC) thermograms of PLLA/ata-PHB blends with different compositions showed two glass transition temperatures, indicating that the PLLA/ata-PHB blends are immiscible in the melt. Surface morphologies of the thin films for PLLA/ata-PHB blends were determined by AFM. Phase separated morphology was recognized from the AFM topography and phase images. The domain size of the components was dependent on the blend ratio. Enzymatic degradation of the PLLA/ata-PHB blends was performed by using both PHB depolymerase and proteinase K. Either PLLA or ata-PHB domains were eroded depending on the kinds of enzyme. Surface morphologies after enzymatic degradation have revealed the phase structure along the depth direction. Enzymatic adsorption of PHB depolymerase was examined on the surface of PLLA/ata-PHB blends. The enzyme molecules were found on both domains of the binary blends. The larger number of enzyme molecules was found on the PLLA domains relative to those on the ata-PHB domains, suggesting the higher affinity of the enzyme against PLLA domain.

Novel aliphatic poly(ester−amide)s with a periodic sequential structure consisting of ester and amide groups were synthesized by two-step polycondensation reactions using adipate, butane-1,4-diamine, and linear diols with different chain lengths, ranging from 3 to 6 methylene groups. Effects of the monomeric structure and sequential length of ester units on the thermal properties and crystalline structure of the obtained periodic copolymers were determined by means of differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). On the basis of DSC measurements, the melting temperatures of the periodic copolymers were higher than those of homopolyesters consisting of the same ester units and tended to increase with an increase in amide content. The copolymers from adipate, butane-1,4-diol, and butane-1,4-diamine had especially high thermal stability compared with the poly(tetramethylene adipate) homopolyester, and the melting temperatures detected were above 200 °C. The X-ray diffraction patterns of periodic copolymers were variable with some copolymers displaying patterns similar to homopolyesters while other copolymers had diffraction patterns that were very different than the homopolyester, dependent on both the monomeric structure of the ester units and the sequential length of the ester units. The formation of different chain packing structures compared to homopolyesters induced the remarkable enhancement of thermal stability, suggesting that molecular chain arrangements based on the intermolecular hydrogen bond interactions play a decisive role in the formation of a thermally stable crystalline region of periodic copolymers and that the formation of intermolecular hydrogen bonds is strongly dependent on both the monomeric structure of ester units and the sequential length of ester units. Furthermore, the effects of annealing treatment on the thermal properties and molecular chain arrangements of periodic copolymers were investigated.

Poly[(R)-3-hydroxybutyrate] (P(3HB)) single crystals were grown isothermally at different crystallization temperatures (Tcs) in a dilute solution. Structural changes of the sedimented single-crystal mats on heating were followed by real-time synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) techniques, and the dependence of the annealing behavior on Tc was examined. The two-dimensional (2D) SAXS pattern clearly demonstrated that the P(3HB) single crystal exhibits a discontinuous increase in the lamellar thickness at an annealing temperature. The onset of the discontinuous thickening depended on Tc or the initial lamellar thickness. The discontinuous thickening occurred at higher temperature as the initial lamellar thickness increased. In the transition region where the discontinuous thickening progressed, the new scattering peak intensity increased while the original one decreased. On the other hand, the crystallinity, estimated from the 2D WAXD patterns, first decreased and then recovered. The lamellar thickening was accompanied by endo- and exothermic signals in differential scanning calorimetry. Accordingly, the discontinuous lamellar thickening is caused by partial melting and recrystallization. The degree of recovery in crystallinity fell with increasing initial lamellar thickness. This is most probably because the crystallization rate becomes slower with increasing temperature in the transition region. After the transition, the long period between the reorganized lamellae increased, while the crystallinity decreased and, finally, diminished due to complete melting.

Summary:The annealing and melting behavior of poly[(R)‐3‐hydroxybutyrate] (P(3HB)) single crystals were followed in real time by synchrotron small‐ (SAXS) and wide‐angle X‐ray scattering (WAXS) measurements. The real‐time SAXS measurements revealed that the P(3HB) single crystal exhibits a discontinuous increase of lamellar thickness during heating. The structural changes as observed by SAXS and WAXS were in response to the thermal properties of single crystals characterized by differential scanning calorimetry.

Abstract

Summary:Novel biodegradable copolymers derived from succinate, butan‐1,4‐diol, and butan‐1,4‐diamine were synthesized by two‐step polycondensation reactions. The obtained copolymers had a periodical‐sequence structure consisting of ester and amide units, and the melting temperatures of the periodic copolymers increased with an increase in amide content. The crystalline structure of the periodic copolymers differs from that of butylene succinate homopolymer (PBS), and these results suggest that the periodically introduced amide units are included in the crystalline phase forming a novel crystalline structure.

The first total synthesis of tricyclic marine alkaloids (±)-fasicularin (2) and (±)-lepadiformine (5) has been accomplished. The key common strategic element for the synthesis is the stereocontrolled intramolecular hetero-Diels–Alder reaction of an N-acylnitroso moiety with an exocyclic diene with or without bromine substitution to control the syn-facial or anti-facial selectivity, respectively. This reaction leads to the trans- or cis-fused decahydroquinoline ring systems 13or 23involving the simultaneous introduction of the nitrogenated quaternary center in a single step. On further elaboration of the six-membered or five-membered ring A, the trans-fused adduct 13provided either (±)-fasicularin (2) or (±)-lepadiformine (5). The hydrochloride salt of synthetic (±)-5was found to be identical with the isolated natural sample of lepadiformine, however, the tricyclic amino alcohol 4that has the proposed structure of lepadiformine in a non-zwitterionic form, derived from the cis-fused adduct 23, was found to be different from lepadiformine by spectral comparison. These results thus unambiguously established the relative stereochemistry of lepadiformine, formerly assigned incorrectly, as shown by 5. The synthesis of natural (−)-enantiomer of lepadiformine was then undertaken using a highly efficient protocol involving a new variant of the N-acyliminium ion-initiated intramolecular spirocyclization in which a conjugated diene was exploited as a π nucleophile. Thus, the synthesis is accomplished in nine steps with 31.4% overall yield, making this the most selective and shortest synthesis of lepadiformine to date. Direct comparison of chiral HPLC analysis of synthetic (−)-lepadiformine and the natural product allowed to assign the absolute configuration of natural lepadiformine to be 3R,5S,7aR,11aR.

Direct visualization of crystal growth in poly(L-lactide) thin films was carried out by using a temperature-controlled atomic force microscopy (AFM). At the initial stage of crystallization, edge-on lamellar crystals have nucleated and elongated. Subsequently, the edge-on lamellar crystals showed S-shaped morphology and changed their orientation from edge-on manner to flat-on one. The curvature of edge-on lamellar crystal has been discussed in terms of inclination and distortion of polymer chains in the crystal. In addition, mechanism on the formation of flat-on crystal from edge-on lamellae was proposed as derivative growth on the basis of in situ AFM observation of crystal growth and enzymatic degradation.

The melting behavior, crystal structure, and spherulitic morphology of melt-crystallized poly(butylene adipate) (PBA) at a temperature range from 25 to 35 °C have been investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and optical microscopy. Two distinct melting behaviors with double peaks have been observed after melt-crystallizing at different temperatures. X-ray analysis proves that these two behaviors arise from two forms of PBA crystal structures. The β-form crystals are formed at temperatures below 31 °C, while the α-form crystals are formed above 29 °C. When the crystallization temperature is 30 ± 1 °C, a mixture of α-form and β-form crystals has been formed. The influences of annealing treatment and sample preparation method on the two forms of PBA crystal structures have been discussed. The results indicate that the low temperature-formed β-form crystals are very sensitive to the preparation conditions. The melting curves at different heating rates for poly(butylene adipate) after melt-crystallized at 25 °C and 33 °C, respectively.

No Abstract

Hemoglobin (Hb) has been widely studied as a raw material for various types of oxygen carriers. In the purification of Hb from red blood cells including virus inactivation and denaturation of other proteins and the long‐term storage of Hb vesicles (HbV), a deoxygenation process is one of the important processes because of the high stability of deoxygenated Hb to heating and metHb formation. Though an oxygenated Hb solution can be deoxygenated with an artificial lung, it is difficult to reduce the oxygen partial pressure of the Hb solution to less than 10 Torr. We developed an electrochemical system for complete deoxygenation of the Hb solution at the cathode compartment using hydrogen containing nitrogen gas at the anode compartment. Oxygen in the Hb solution was reduced to OH−at the cathode compartment within several minutes at a potential value of −1.67 V and was finally converted to water by neutralization with H+from the anode in the whole system. The resulting completely deoxygenated Hb could tolerate heat treatment at 62 °C for 10 h with no denaturation of deoxygenated Hb. The metHb formation rate of reoxygenated Hb at 37 °C was not changed after heat treatment. Furthermore, vesicular stomatitis virus (VSV) could be inactivated at an inactivation degree of more than 5.96 log by heat treatment.

[Poly(ethyleneglycol)]-modified hemoglobin vesicles (PEG-HbV), [nba type of encapsulated hemoglobin, have been developed as artificial oxygen carriers and it is important to evaluate their blood compatibility. We studied the effects of PEG-HbV on human polymorphonuclear neutrophils (PMNs) in vitro, focusing on the functional responses to N-formyl-methionyl-leucyl-phenylalanine (fMLP) as an agonist. The pretreatment of the PMNs with PEG-HbV up to a concentration of 60 mgdl Hb did not affect the fMLP-triggered chemotactic activity. In parallel to these results, the fMLP-induced upregulation of CD11b (Mac-1) levels on the PEG-HbV-pretreated PMNs was comparable to that of untreated cells. Furthermore, the pretreatment of the PMNs with the PEG-HbV even at 600 mgdl Hb did not affect the gelatinase B (Matrix methalloproteinase-9 (MMP-9)) release, suggesting that the fMLP-induced release of secondary and tertiary granules was normal. In addition, the fMLP-triggered superoxide production of the PMNs was unchanged by the pretreatment with the PEG-HbV at 600 mgdl Hb. Thus, these results suggest that PEG-HbV, at the concentrations studied, have no aberrant effects on the fMLP-triggered functions of human PMNs.

RGS8 was originally identified as an RGS protein specifically expressed in neuronally differentiated P19 cells. We generated a polyclonal antibody specific to rat RGS8 using a synthetic peptide. When nonneural cells (DDT1MF2, CHO, and NIH3T3) transfected with rat RGS8 cDNA were immuno-stained with this antibody, the RGS8 protein was mainly detected in the nuclei. Since RGS8 mRNA was exclusively expressed in Purkinje cells of the cerebellum in the rat brain, we further examined the cellular distribution of the RGS8 protein in Purkinje cells using cultured cerebellar cells and tissue sections of the cerebellum. The RGS8 protein was excluded from the nuclei and distributed in the cell body and dendrites, but not in the axons of Purkinje cells. These results demonstrate the presence of a mechanism controlling the distribution of RGS8 protein in cerebellar Purkinje cells.

The solid‐state structures and thermal properties of melt‐crystallized films of random copolymers of (R)‐3‐hydroxybutyric acid (3HB) with different hydroxyalkanoic acids such as (R)‐3‐hydroxypentanoic acid (3HV), (R)‐3‐hydroxyhexanoic acid (3HH), medium‐chain‐length (R)‐3‐hydroxyalkanoic acids (mcl‐3HA; C8‐C12), 4‐hydroxybutyric acid (4HB), and 6‐hydroxyhexanoic acid (6HH) were characterized by means of small‐angle X‐ray scattering, differential scanning calorimetry, and optical microscopy. The randomly distributed second monomer units except for 3HV in copolyesters act as defects of P(3HB) crystal and are excluded from the P(3HB) crystalline lamellae. The lamellar thickness of copolymers decreased with an increase in either the main‐chain or the side‐chain carbon numbers of second monomer units. In addition, the growth rate of spherulites decreased with an increase in the carbon numbers of second monomer units for copolymers with an identical comonomer composition. These results indicate that the steric bulkiness of second monomer unit affects on the crystallization of 3HB segments in random copolyesters.