Toyohashi University of Technology

Numerous biodegradable polymers have been developed in the last two decades. In terms of application, biodegradable polymers are classified into three groups: medical, ecological, and dual application, while in terms of origin they are divided into two groups: natural and synthetic. This review article will outline classification, requirements, applications, physical properties, biodegradability, and degradation mechanisms of representative biodegradable polymers that have already been commercialized or are under investigation. Among the biodegradable polymers, recent developments of aliphatic polyesters, especially polylactides and poly(lactic acid)s, will be mainly described in the last part.

Poly(lactide)s [i.e. poly(lactic acid) (PLA)] and lactide copolymers are biodegradable, compostable, producible from renewable resources, and nontoxic to the human body and the environment. They have been used as biomedical materials for tissue regeneration, matrices for drug delivery systems, and alternatives for commercial polymeric materials to reduce the impact on the environment. Since stereocomplexation or stereocomplex formation between enantiomeric PLA, poly(L-lactide) [i.e. poly(L-lactic acid) (PLLA)] and poly(D-lactide) [i.e. poly(D-lactic acid) (PDLA)] was reported in 1987, numerous studies have been carried out with respect to the formation, structure, properties, degradation, and applications of the PLA stereocomplexes. Stereocomplexation enhances the mechanical properties, the thermal-resistance, and the hydrolysis-resistance of PLA-based materials. These improvements arise from a peculiarly strong interaction between L-lactyl unit sequences and D-lactyl unit sequences, and stereocomplexation opens a new way for the preparation of biomaterials such as hydrogels and particles for drug delivery systems. It was revealed that the crucial parameters affecting stereocomplexation are the mixing ratio and the molecular weight of L-lactyl and D-lactyl unit sequences. On the other hand, PDLA was found to form a stereocomplex with L-configured polypeptides in 2001. This kind of stereocomplexation is called "hetero-stereocomplexation" and differentiated from "homo-stereocomplexation" between L-lactyl and D-lactyl unit sequences. This paper reviews the methods for tracing PLA stereocomplexation, the methods for inducing PLA stereocompelxation, the parameters affecting PLA stereocomplexation, and the structure, properties, degradation, and applications of a variety of stereocomplexed PLA materials.

DOI: 10.1002/mabi.200500062 The author would like to announce the following correction. Figure 1 contains some errors with respect to the polymer configurations. 1) Page 571, Figure 1 The author apologizes for any inconvenience caused.

Nb, Ta and Zr are the favorable non-toxic alloying elements for titanium alloys for biomedical applications. Low rigidity titanium alloys composed of non-toxic elements are getting much attention. The advantage of low rigidity titanium alloy for the healing of bone fracture and the remodeling of bone is successfully proved by fracture model made in tibia of rabbit. Ni-free super elastic and shape memory titanium alloys for biomedical applications are energetically developed. Titanium alloys for not only implants, but also dental products like crowns, dentures, etc. are also getting much attention in dentistry. Development of investment materials suitable for titanium alloys with high melting point is desired in dental precision castings. Bioactive surface modifications of titanium alloys for biomedical applications are very important for achieving further developed biocompatibility. Low cost titanium alloys for healthcare goods, like general wheel chairs, etc. has been recently proposed.

<p>Journal of Physics D: Applied Physics published the first Plasma Roadmap in 2012 consisting of the individual perspectives of 16 leading experts in the various sub-fields of low temperature plasma science and technology. The 2017 Plasma Roadmap is the first update of a planned series of periodic updates of the Plasma Roadmap. The continuously growing interdisciplinary nature of the low temperature plasma field and its equally broad range of applications are making it increasingly difficult to identify major challenges that encompass all of the many sub-fields and applications. This intellectual diversity is ultimately a strength of the field. The current state of the art for the 19 sub-fields addressed in this roadmap demonstrates the enviable track record of the low temperature plasma field in the development of plasmas as an enabling technology for a vast range of technologies that underpin our modern society. At the same time, the many important scientific and technological challenges shared in this roadmap show that the path forward is not only scientifically rich but has the potential to make wide and far reaching contributions to many societal challenges.</p>

It has been found that, dependent on the crystallization temperature (Tc), the disorder (α‘) and order (α) phases of poly(l-lactide) (PLLA) are formed at low (Tc < 100 °C) and high (Tc ≥ 120 °C) temperatures, respectively. In the DSC curves, the sample with α‘ phase demonstrates a peculiar small exothermal peak around 160 °C just prior to the melting point, while the sample crystallized at temperatures around 120 °C (between 110 and 130 °C) shows a double melting behavior. These distinct thermal behaviors of various PLLA samples were investigated in detail by simultaneous measurements of WAXD and DSC. It is confirmed that the small exothermal peak corresponds to the disorder-to-order (α‘-to-α) phase transition, in which the chain packing of the crystal lattice becomes more compacted. In the process of the α‘-to-α phase transition, the isosbestic points were found in the temperature-dependent WAXD profiles. So far, the α‘-to-α transition was considered to occur apparently continuously as long as the main 200/110 peak was measured, but detailed investigation of higher 2θ peaks has revealed for the first time that the α‘ phase transforms discretely to the α phase in the first-order transition mode. On the basis of the X-ray diffraction and DSC data, a kind of phase diagram concerning the α‘ and α forms has been constructed reasonably.

Recently, we reported the isothermal crystallization behaviors of poly(l-lactic acid) (PLLA) from the melt and glassy states, respectively [J. Phys. Chem. B 2004, 108, 11514; Macromolecules 2004, 37, 6433]. Surprisingly, the quite different infrared (IR) spectral evolutions occur in the two crystallization processes at different temperatures in which the same crystal modification is expected to be formed. To clarify this unusual phenomenon, the crystal modifications and thermal behavior of PLLA samples prepared under different crystallization temperatures are investigated in detail by TEM, WAXD, and FTIR techniques. On the basis of the WAXD and IR data, a new crystal modification named the α form is proposed for the crystal structure of PLLA samples annealed at temperature below 120 °C. Such crystal modification with loose 103 helical chain packing is less thermally stable than the standard α form of PLLA. This assignment can explain all the experiment observations well. Other possible mechanisms for the IR spectral difference of bulk PLLA samples annealed at different temperatures are also discussed.

Reverse-phase high-performance liquid chromatography and photodiode array detection were used to analyze the microbial quinones of influent sewage and activated sludge in a sewage treatment plant. Significant differences in quinone patterns were noted between the sewage and activated sludge. Unlike the activated sludge, the sewage had low ratios of menaquinones to ubiquinones, and contained menaquinone-6 as the most abundant menaquinone and negligible amounts of partially hydrogenated menaquinones. A photodiode array analysis revealed that the sewage also contained considerable amounts of plastoquinones and vitamin K1, both of which are specific to photosynthetic electron transport in cyanobacteria and chloroplasts. These results suggest that the microbial population structure of sewage is markedly different from that of activated sludge. Relationships between changes in the community structure of the sewage and activated sludge were also discussed on the basis of the results of a numerical analysis of lipoquinone patterns.

The sixth blind test of organic crystal structure prediction (CSP) methods has been held, with five target systems: a small nearly rigid molecule, a polymorphic former drug candidate, a chloride salt hydrate, a co-crystal and a bulky flexible molecule. This blind test has seen substantial growth in the number of participants, with the broad range of prediction methods giving a unique insight into the state of the art in the field. Significant progress has been seen in treating flexible molecules, usage of hierarchical approaches to ranking structures, the application of density-functional approximations, and the establishment of new workflows and `best practices' for performing CSP calculations. All of the targets, apart from a single potentially disordered Z' = 2 polymorph of the drug candidate, were predicted by at least one submission. Despite many remaining challenges, it is clear that CSP methods are becoming more applicable to a wider range of real systems, including salts, hydrates and larger flexible molecules. The results also highlight the potential for CSP calculations to complement and augment experimental studies of organic solid forms.

Two novel benzoxazine monomers containing allyl groups: 3-allyl-3,4-dihydro-2H-1,3-benzoxazine and bis(3-allyl-3,4-dihydro-2H-1,3-benzoxazinyl)isopropane have been synthesized from phenol and Bisphenol A with allylamine and formaldehyde. Their DSC exhibit two exotherms at ca. 145 °C and at ca. 220 °C which correspond to allyl and oxazine thermal polymerization, respectively. Both monomers undergo thermal cure with the formation of thermosets having excellent thermomechanical properties. These thermosets exhibit higher Tg (ca. 300 °C), maintain their storage moduli at higher temperature, and have better thermal stability than the corresponding polybenzoxazines without allyl groups.

Abstract Supercapacitors are increasingly used for energy conversion and storage systems in sustainable nanotechnologies. Graphite is a conventional electrode utilized in Li-ion-based batteries, yet its specific capacitance of 372 mA h g −1 is not adequate for supercapacitor applications. Interest in supercapacitors is due to their high-energy capacity, storage for a shorter period and longer lifetime. This review compares the following materials used to fabricate supercapacitors: spinel ferrites, e.g., MFe 2 O 4 , MMoO 4 and MCo 2 O 4 where M denotes a transition metal ion; perovskite oxides; transition metals sulfides; carbon materials; and conducting polymers. The application window of perovskite can be controlled by cations in sublattice sites. Cations increase the specific capacitance because cations possess large orbital valence electrons which grow the oxygen vacancies. Electrodes made of transition metal sulfides, e.g., ZnCo 2 S 4 , display a high specific capacitance of 1269 F g −1 , which is four times higher than those of transition metals oxides, e.g., Zn–Co ferrite, of 296 F g −1 . This is explained by the low charge-transfer resistance and the high ion diffusion rate of transition metals sulfides. Composites made of magnetic oxides or transition metal sulfides with conducting polymers or carbon materials have the highest capacitance activity and cyclic stability. This is attributed to oxygen and sulfur active sites which foster electrolyte penetration during cycling, and, in turn, create new active sites.

The human gut microbiome has profound influences on the host's health largely through its interference with various intestinal functions. As recent studies have suggested diversity in the human gut microbiome among human populations, it will be interesting to analyse how gut microbiome is correlated with geographical, cultural, and traditional differences. The Japanese people are known to have several characteristic features such as eating a variety of traditional foods and exhibiting a low BMI and long life span. In this study, we analysed gut microbiomes of the Japanese by comparing the metagenomic data obtained from 106 Japanese individuals with those from 11 other nations. We found that the composition of the Japanese gut microbiome showed more abundant in the phylum Actinobacteria, in particular in the genus Bifidobacterium, than other nations. Regarding the microbial functions, those of carbohydrate metabolism were overrepresented with a concurrent decrease in those for replication and repair, and cell motility. The remarkable low prevalence of genes for methanogenesis with a significant depletion of the archaeon Methanobrevibacter smithii and enrichment of acetogenesis genes in the Japanese gut microbiome compared with others suggested a difference in the hydrogen metabolism pathway in the gut between them. It thus seems that the gut microbiome of the Japanese is considerably different from those of other populations, which cannot be simply explained by diet alone. We postulate possible existence of hitherto unknown factors contributing to the population-level diversity in human gut microbiomes.

A variety of octadecylsilylated silica gel phases are prepared under various conditions, and their chromatographic properties are studied in order to carry out chromatographic characterization of commercial C18 packing materials. The test scheme, utilizing several sets of solutes, provides information about hydrophobicity, steric selectivity, and the extent of hydrogen bonding and electrostatic interactions. The results permit the estimation of how the commercial packing materials were prepared.

Electrostatic precipitators have been used widely in industry, and play an important role in environmental protection. An electrostatic precipitator (ESP) can be operated with a high collection efficiency and a low pressure drop. Recently, an ESP also has been used for cleaning indoor air. In this review, principles of electrostatic precipitation, such as particle charging, migration velocity of charged particles and collection efficiency, are described. The performance of the ESP deteriorates by abnormal phenomena, including back corona for treating high resistivity dust, abnormal re-entrainment for low resistivity dust, and corona quenching for fine dusts. To cope with these phenomena, new technologies have been developed. Pulsed energization is a technique which copes with high resistivity dusts, and this results in lower power consumption. Using pulsed energization, non-thermal plasma can be generated and chemical reactions can be promoted for treating gaseous pollutants such as NO and volatile organic compounds. Wet ESP can also remove dusts and gaseous pollutants simultaneously. These new advancements will widen the field of application of electrostatic precipitation. Some novel applications of ESP, such as removal of dioxin from incinerators, are also included in this review.

Targeted deletion of metabotropic glutamate receptor-subtype 1 (mGluR1) gene can cause defects in development and function in the cerebellum. We introduced the mGluR1alpha transgene into mGluR1-null mutant [mGluR1 (-/-)] mice with a Purkinje cell (PC)-specific promoter. mGluR1-rescue mice showed normal cerebellar long-term depression and regression of multiple climbing fiber innervation, events significantly impaired in mGluR1 (-/-) mice. The impaired motor coordination was rescued by this transgene, in a dose-dependent manner. We propose that mGluR1 in PCs is a key molecule for normal synapse formation, synaptic plasticity, and motor control in the cerebellum.

When the constitutive materials of photonic crystals (PCs) are magnetic, or even only a defect introduced in PCs is magnetic, the resultant PCs exhibit very unique optical and magneto-optical properties. The strong photon confinement in the vicinity of magnetic defects results in large enhancement in linear and nonlinear magneto-optical responses of the media. Novel functions, such as band Faraday effect, magnetic super-prism effect and non-reciprocal or magnetically controllable photonic band structure, are predicted to occur theoretically. All the unique features of the media arise from the existence of magnetization in media, and hence they are called magnetophotonic crystals providing the spin-dependent nature in PCs.

It is important to measure and analyze people behavior to design systems which interact with people. This article describes a portable people behavior measurement system using a three-dimensional LIDAR. In this system, an observer carries the system equipped with a three-dimensional Light Detection and Ranging (LIDAR) and follows persons to be measured while keeping them in the sensor view. The system estimates the sensor pose in a three-dimensional environmental map and tracks the target persons. It enables long-term and wide-area people behavior measurements which are hard for existing people tracking systems. As a field test, we recorded the behavior of professional caregivers attending elderly persons with dementia in a hospital. The preliminary analysis of the behavior reveals how the caregivers decide the attending position while checking the surrounding people and environment. Based on the analysis result, empirical rules to design the behavior of attendant robots are proposed.

The nature of the "peculiarly strong" interaction between the poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) chains was investigated by real time infrared spectroscopy during the isothermal melt crystallization process of the PLLA/PDLA stereocomplex. A very small low-frequency shift (about 1 cm-1) of νas(CH3) and a larger low-frequency shift (about 5 cm-1) of ν(CO) were observed. The typical butterfly pattern in the two-dimensional (2D) asynchronous correlation spectrum and the second-derivative spectra reveal that there is a "peak shift" for ν(CO). The red shifts of the stretching vibration modes of the methyl and carbonyl groups suggest that the interaction between the PLLA/PDLA stereocomplex is ascribed to CH3···OC hydrogen bonding. Another interesting result is that the peak shift of the ν(CO) band already occurs in the induction period, which indicates that the CH3···OC interaction is the driving force for forming the racemic nucleation of the PLLA/PDLA stereocomplex. Moreover, the 2D correlation analysis indicates that the structural adjustment of the CH3 group occurs prior to that of the C−O−C backbone during the stereocomplexation process of PLLA/PDLA. The CH3···OC interaction may be the reason for this sequence of structural changes.

Thermally conductive ceramic/plastic composite materials are needed in various industries for thermal management. The present work aimed at creating composite films of hexagonal boron nitride (h-BN) particles and polyimide. A thermal conductivity of 7 W m−1 K−1 was achieved at solids loading of 60 vol% with flexibility maintained.

The significance of graphene and its two-dimensional (2D) analogous inorganic layered materials especially as hexagonal boron nitride (h-BN) and molybdenum disulphide (MoS2) for “clean energy” applications became apparent over the last few years due to their extraordinary properties. In this review article we study the current progress and selected challenges in the syntheses of graphene, h-BN and MoS2 including energy storage applications as supercapacitors and batteries. Various substrates/catalysts (metals/insulator/semiconducting) have been used to obtain graphene, h-BN and MoS2 using different kinds of precursors. The most widespread methods for synthesis of graphene, h-BN and MoS2 layers are chemical vapor deposition (CVD), plasma-enhanced CVD, hydro/solvothermal methods, liquid phase exfoliation, physical methods etc. Current research has shown that graphene, h-BN and MoS2 layered materials modified with metal oxide can have an insightful influence on the performance of energy storage devices as supercapacitors and batteries. This review article also contains the discussion on the opportunities and perspectives of these materials (graphene, h-BN and MoS2) in the energy storage fields. We expect that this written review article including recent research on energy storage will help in generating new insights for further development and practical applications of graphene, h-BN and MoS2 layers based materials.