Biodegradable polymers based on renewable resources. VI. Synthesis and biodegradability of poly(ester carbonate)s containing 1,4:3,6‐dianhydro‐D‐glucitol and sebacic acid units

Poly(ester carbonate)s with different compositions were synthesized by bulk polycondensation of 1,4:3,6‐dianhydro‐D ‐glucitol with diphenyl sebacate and diphenyl carbonate in the presence of zinc acetate as a catalyst. Most of the poly(ester carbonate)s as well as the corresponding polycarbonate were amorphous, except the poly(ester carbonate) with a small carbonate content and the corresponding polyester, which are semicrystalline. All these poly(ester carbonate)s are soluble in chloroform, pyridine, dimethylformamide, dimethyl sulfoxide, and N,N‐dimethylacetamide. Soil burial degradation tests, biochemical oxygen demand (BOD) measurements in an activated sludge, and enzymatic degradation tests indicated that these poly(ester carbonate)s are potentially biodegradable. The biodegradability was found to be maximum for the poly(ester carbonate)s with carbonate contents of 10–20 mol % and to decrease markedly for the poly(ester carbonate)s with the carbonate content above 50 mol %. The biodegradability of the poly(ester carbonate)s is discussed in terms of the crystallinity, glass transition temperature, and surface hydrophobicity of the polymer films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 872–880, 2002     

An investigation of the age hardening behavior of PM 2024Al-Fe-Ni alloys and the effect of consolidation conditions

The aging ability of two PM alloys based on 2024Al with Fe and Ni addition has been investigated by means of EDX, XRD, DSC, TEM and Vickers hardness analysis, and compared with that of the base alloy PM 2024 aluminum. Effect of consolidation temperature and powder size on the aging behavior of the 3F5N alloy was also studied. The results showed that the 3F0N alloy, PM 2024Al with 3 mass% Fe single addition, exhibited poor aging ability compared to 2024 alloy. In this alloy, the amount of solid solution Cu was found to decrease by forming Al₇Cu₂Fe compound during solidification, resulting in a lower amount of Cu dissolved into the α-Al matrix of the extrusions during the solution treatment. Whereas the 3F5N alloy, PM 2024Al with a 3 mass% Fe and 5 mass% Ni combined addition, showed almost the same age hardenability compared to PM 2024 alloy. Due to the addition of Ni, the amount of insoluble compound Al₇Cu₂Fe was decreased by the formation of Al₉FeNi phase in the 3F5N alloy. Thus, more Cu could be dissolved into the matrix during the solution treatment. A quantity of GPB zone could be formed in the 3F5N alloy during the aging resulting in higher age hardenability than the 3F0N alloy. The extrusion temperature and powder size were found to affect the aging hardenability of the 3F5N extrusions. Although higher age hardenability could be obtained in the 3F5N specimen extruded from powders with the relatively larger diameter, it was found that with decreasing extrusion temperature the higher aging ability could also be obtained in the 3F5N alloy extruded from finer powders. This revised version was published online in September 2006 with corrections to the Cover Date.     

Transmission electron microscopy study of GdBa2Cu3O7−x containing nano-sized BaMO3 (M: Hf, Zr, Sn) rods fabricated by pulsed laser deposition

Three types of superconducting GdBa₂Cu₃O_7?x (GdBCO) layers containing rods of either BaHfO₃ (BHO), BaZrO₃ (BZO), or BaSnO₃ (BSO) were fabricated by pulsed laser deposition on Hastelloy substrates with a CeO₂ based textured buffer layer. The critical currents (J _c) values of the GdBCO layers containing those nano-rods are enhanced compared with those of pristine GdBCO layer in high magnetic fields. In order to investigate the relationships between their superconductive properties and their nanostructures, they were characterized in detail by transmission electron microscopy (TEM). TEM is the only method for direct observation of these nano-rods in the GdBCO grains. The GdBCO layers were mainly composed of c-axis oriented GdBCO grains containing numerous nano-sized rods. The crystal orientation relationships between the GdBCO and the nano-rods were as follows; (001)GdBCO//(001)nano-rods and (100)GdBCO//(100) nano-rods. The average diameters of the BHO and the BZO nano-rods were 4.5 and 5.6 nm, respectively. The BSO nano-rods were thicker than other rods. These nano-rods in the central region of the c-axis oriented GdBCO grains were aligned parallel to the c-axis of the GdBCO, while nano-rods in the outer region of the c-axis oriented grains were tilted away from the c-axis. With increase in the thickness of the GdBCO layers, the ratio of the BZO or the BSO nano-rods aligned parallel to the c-axis to those tilted away from the c-axis decreased, so that the J _c-B-θ profiles of the thicker GdBCO layers containing the BZO or the BSO nano-rods became flatter. The BHO nano-rods were homogeneously distributed throughout the GdBCO, and their average length of was less than that of the other nano-rods. The homogeneous distribution and short length of the BHO nano-rods enhanced the J _c values of the GdBCO layers containing them in high magnetic fields. The J _c-B-θ profiles of the GdBCO layers containing the BHO were independent of the layer thickness. From these results, we will discuss about the morphologies and distributions of suitable vortex pinning for applications of GdBCO coated conductor in high magnetic fields.     

High strength and toughness of double physically cross-linked hydrogels composed of polyvinyl alcohol and calcium alginate

The weak mechanical properties of hydrogels, especially physically cross-linked hydrogels are usually a major factor to hinder their application. To solve this problem, in this work, we prepared a high strength and toughness of double physically cross-linked (PDN) hydrogels composed of crystalline domain cross-linked polyvinyl alcohol (PVA) and Ca²⁺-cross-linked alginate (Alg). With a further annealing treatment, the noncovalent cross-linked network via the formed crystalline promote the as-prepared PDN PVA/Alg hydrogel to exhibit well mechanical properties with the tensile strength of ~1.94 MPa, elongation at break of ~607% and Young's modulus of ~0.45 MPa (above 70 wt% of water content). By analyzing the mechanism of improving the hydrogel mechanical properties, it is found that annealing can effectively improve the crystallinity of PVA in the hydrogel, and then greatly improve the mechanical properties of the hydrogel. This provides a general method for improving the mechanical properties of PVA PDN hydrogels. In addition, the PDN PVA/Alg hydrogel was also proved to have good ionic conductivity of 1.70 S m⁻¹. These desirable properties make the prepared physically cross-linked hydrogels promising materials for medical and biosensing fields.     

Identification of Tumor-Suppressive miR-30e-3p Targets: Involvement of SERPINE1 in the Molecular Pathogenesis of Head and Neck Squamous Cell Carcinoma

Recently, our studies revealed that some passenger strands of microRNAs (miRNAs) were closely involved in cancer pathogenesis. Analysis of miRNA expression signatures showed that the expression of miR-30e-3p (the passenger strand of pre-miR-30e) was significantly downregulated in cancer tissues. In this study, we focused on miR-30e-3p (the passenger strand of pre-miR-30e). We addressed target genes controlled by miR-30e-3p that were closely associated with the molecular pathogenesis of head and neck squamous cell carcinoma (HNSCC). Ectopic expression assays demonstrated that the expression of miR-30e-3p attenuated cancer cell malignant phenotypes (e.g., cell proliferation, migration, and invasive abilities). Our analysis of miR-30e-3p targets revealed that 11 genes (ADA, CPNE8, C14orf126, ERGIC2, HMGA2, PLS3, PSMD10, RALB, SERPINE1, SFXN1, and TMEM87B) were expressed at high levels in HNSCC patients. Moreover, they significantly predicted the short survival of HNSCC patients based on 5-year overall survival rates (p < 0.05) in The Cancer Genome Atlas (TCGA). Among these targets, SERPINE1 was found to be an independent prognostic factor for patient survival (multivariate Cox regression; hazard ratio = 1.6078, p < 0.05). Aberrant expression of SERPINE1 was observed in HNSCC clinical samples by immunohistochemical analysis. Functional assays by targeting SERPINE1 expression revealed that the malignant phenotypes (e.g., proliferation, migration, and invasion abilities) of HNSCC cells were suppressed by the silencing of SERPINE1 expression. Our miRNA-based approach will accelerate our understanding of the molecular pathogenesis of HNSCC.     

Core-shell microbioreactor microencapsulated denitrifying bacteria for nitrate-nitrogen treatment

Summary Droplets of water-in-oil-in-water (w/o/w) emulsion were prepared using sodium alginate solution with denitrifying bacteria (Paracoccus denitrificans IFO13301) and dichloromethane (DCM) with polymethylmethacrylate (PMMA). By phase-separation and solvent-evaporation these droplets could be formed into core-shell PMMA microencapsulated denitrifying bacteria (PMMA-MC) possessing a large single core and a highly porous wall. The average thickness of the PMMA shell was 30 μm and the denitrifying bacteria were incorporated in the inner core at a high density. The PMMA-MC completely reduced 20 mg/L nitrate-nitrogen (NO₃-N) and the intermediate product, nitrite-nitrogen (NO₂-N), to N₂ in the presence of H₂ using a batchwise method. Thus, incorporated denitrifying bacteria can be used to treat water polluted with NO₃-N. The PMMA-MC can be used repeatedly, and the third denitrification experiment directly denitrified (NO₃-N → N₂) without the intermediate step (NO₃-N → NO₂-N). In addition, the PMMA-MC with decreased activity could be reactivated by incubating in a culture medium.     

Solitary plasmacytoma of the mandible. Case report and review of the literature

A case of solitary plasmacytoma of the mandible is presented. Review of the literature disclosed the following characteristics regarding the clinical course and prognosis. The patients ages ranged from 34 to 76 years, with a mean of 53 years; there was a marked preponderance of males. The site of predilection was the posterior portion of the mandible. The common symptom was a non-painful swelling of the mandible of long duration, and radiological features were non-specific. Monoclonal immunoglobulin was initially detected in 42% of the evaluated patients. The majority of patients were treated with radiation therapy with a mean dose of 48Gy with or without surgery. The period of follow-up ranged from 4 months to 12 years, and 17% of the patients progressed to multiple myeloma within 1 year.     

Flow range enhancement by secondary flow effect in low solidity circular cascade diffusers

High-pressure ratio and wide operating range are highly required for compressors and blowers. The technical issue of the design is achievement of suppression of flow separation at small flow rate without deteriorating the efficiency at design flow rate. A numerical simulation is very effective in design procedure, however, cost of the numerical simulation is generally high during the practical design process, and it is difficult to confirm the optimal design which is combined with many parameters. A multi-objective optimization technique is the idea that has been proposed for solving the problem in practical design process. In this study, a Low Solidity circular cascade Diffuser (LSD) in a centrifugal blower is successfully designed by means of multi-objective optimization technique. An optimization code with a meta-model assisted evolutionary algorithm is used with a commercial CFD code ANSYS-CFX. The optimization is aiming at improving the static pressure coefficient at design point and at low flow rate condition while constraining the slope of the lift coefficient curve. Moreover, a small tip clearance of the LSD blade was applied in order to activate and to stabilize the secondary flow effect at small flow rate condition. The optimized LSD blade has an extended operating range of 114 % towards smaller flow rate as compared to the baseline design without deteriorating the diffuser pressure recovery at design point. The diffuser pressure rise and operating flow range of the optimized LSD blade are experimentally verified by overall performance test. The detailed flow in the diffuser is also confirmed by means of a Particle Image Velocimeter. Secondary flow is clearly captured by PIV and it spreads to the whole area of LSD blade pitch. It is found that the optimized LSD blade shows good improvement of the blade loading in the whole operating range, while at small flow rate the flow separation on the LSD blade has been successfully suppressed by the secondary flow effect.     

Multi-point optimization of recirculation flow type casing treatment in centrifugal compressors

High-pressure ratio and wide operating range are highly required for a turbocharger in diesel engines.A recirculation flow type casing treatment is effective for flow range enhancement of centrifugal compressors.Two ring grooves on a suction pipe and a shroud casing wall are connected by means of an annular passage and stable recirculation flow is formed at small flow rates from the downstream groove toward the upstream groove through the annular bypass.The shape of baseline recirculation flow type casing is modified and optimized by using a multi-point optimization code with a metamodel assisted evolutionary algorithm embedding a commercial CFD code CFX from ANSYS.The numerical optimization results give the optimized design of casing with improving adiabatic efficiency in wide operating flow rate range.Sensitivity analysis of design parameters as a function of efficiency has been performed.It is found that the optimized casing design provides optimized recirculation flow rate,in which an increment of entropy rise is minimized at grooves and passages of the rotating impeller.     

Dynamic optically reconfigurable gate array very large-scale integration with partial reconfiguration capability

We present a proposal of a partial reconfiguration architecture for optically reconfigurable gate arrays and present an 11,424 gate dynamic optically reconfigurable gate array VLSI chip that was fabricated on a 96.04 mm(2) chip using an 0.35 μm three-metal complementary metal oxide semiconductor process technology. The fabricated VLSI chip achieved a 2.21 μs partial reconfiguration.