Fabrication of nanostructured polycarbonate/poly(methyl methacrylate) blends with improved optical and mechanical properties by high‐shear processing

The structure and properties of polycarbonate (PC)/poly(methyl methacrylate) (PMMA) blends fabricated using a high‐shear extruder at different shear rates were investigated. It was found that the morphologies of the blends were greatly dependent on the shear rate exerted during melt processing. High‐shear processing leads to a nanostructured PC/PMMA blend, in which PMMA domains with a size of less than 50 nm are homogeneously dispersed in the PC matrix. The prepared nanostructured blends exhibit not only excellent optical properties with a transmittance of more than 90% in the visible region but also a higher modulus than pure PC. In contrast, the PMMA domain size ranges from submicron to micrometer for the same blends processed at a low‐shear rate. These blends are opaque and display much lower elongation at break compared with the blends processed at a high‐shear rate. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Effect of vanadium and chromium on the microstructural features of V–Cr–Mn–Ni spheroidal carbide cast irons

The objective of this investigation is to study the influence of vanadium（5.0wt%–10.0wt%） and chromium（0–9.0wt%） on the microstructure and hardness of Cr-V-Mn-Ni white cast irons with spheroidal vanadium carbides. The alloys＇ microstructural features are presented and discussed with regard to the distribution of phase elements. The structural constituents of the alloys are spheroidal VC, proeutectoid cementite, ledeburite eutectic, rosette-shaped carbide eutectic（based on M7C3）, pearlite, martensite, and austenite. Their combinations and area fraction（AF） ratios are reported to be influenced by the alloys＇ chemical composition. Spheroidized VC particles are found to be sites for the nucleation of carbide eutectics. Cr and V are shown to substitute each other in the VC and M7C3 carbides, respectively. Chromium alloying leads to the formation of a eutectic（γ-Fe ＋ М7С3）, preventing the appearance of proeutectoid cementite in the structure. Vanadium and chromium are revealed to increase the total carbide fraction and the amount of austenite in the matrix. Cr is observed to play a key role in controlling the metallic matrix microstructure.     

The dilute solution properties of maleic anhydride and maleic acid copolymers: 1. Light scattering, osmotic pressure and viscosity measurements

Dilute solution behaviour of poly(maleic anhydride-co-ethyl vinyl ether) and poly(maleic acid-co-ethyl vinyl ether) has been investigated by light scattering, osmotic pressure, and viscosity measurements. The molecular weights ($\text{M}\text{?}{}_{\mathrm{w}}$ and $\text{M}\text{?}{}_{\mathrm{n}}$), the second virial coefficients A₂, and the intrinsic viscosities [η] have been determined for three states of this copolymer: anhydride-form, H-form, and Na-salt independently. The constants in the Mark-Houwink relations were obtained for the above three states under different solvent conditions. The molecular weight of the anhydride-form is found to be higher than that of the acid-form or the Na-salt, suggesting the degradation in a process of hydrolysis. The second virial coefficient A₂ as well as the Mark-Houwink relation indicates that the anhydride-form and H-form behave as flexible polymer chains in good solvents. However, the polymer coil of Na-salt is highly expanded even at saturated NaCl concentration.     

Stoichiometric formation of poly-ion complexes between human carboxyhemoglobin and potassium poly(vinyl alcohol) sulfate

Summary Colloid titrations of human carboxyhemoglobin were carried out at different pH. The total number of basic groups in the hemoglobin was 95, as evaluated by the titration with potassium poly (vinyl alcohol) sulfate (KPVS). The value estimated was comparable with that obtained from the amino acid sequence of human hemoglobin. This finding indicates the stoichiometric salt-linkage formation between the basic groups in the hemoglobin and the KOSO₃-groups in KPVS.     

Adhesion between polymer surface modified by graft polymerization and tissue during surgery using an ultrasonically activated scalpel device

In the field of surgery, achieving adhesion between a polymer implant and tissue poses a challenge considering that suturing is not appropriate for the stability of such implants. An ultrasonically activated scalpel that generates heat by mechanical vibration and promotes adhesion between a polymer implant and native tissue by pressing the two materials together has very good potential for application in the field. To determine the type of polymer that is suitable for the purpose, we investigated polyethylene (PE) and polystyrene (PS) films, the surfaces of which were activated by corona discharge. Graft polymerization was then performed on the corona‐treated surfaces to vary their properties. The corona‐treated PE and PS films grafted with poly(acrylic acid), poly(methacrylic acid), poly(vinyl benzylacrylic acid), and poly(hydroxylethyl acrylate), respectively, adhered to the tissue when the ultrasonically activated scalpel was applied. The heat generated by the mechanical vibration and the applied pressure enabled the carboxyl or hydroxyl groups to bond with the proteins in the extracellular matrix. We therefore concluded that it was possible to integrate this technique in the development of new types of polymer devices that could be stably implanted in a living body. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40885.     

Preparation of ultrafine polyurethane fiber web by laser‐electrospinning combined with air blowing

Thermoplastic polyurethane fiber webs were prepared using a laser‐heated electrospinning process combined with air blowing. The effect of spinning conditions such as air flow rate and air temperature on fiber diameter and molecular weight was investigated. Although the average fiber diameter decreased with increased air flow rate at each air temperature, the diameter increased when the air flow rate was >15 NL min^?1. In addition, the fiber was comparatively thicker with an increase in the air temperature. The variation in the fiber diameter tends to increase with the air flow rate, and a reduction in the molecular weight of the fiber by thermal degradation was suppressed. The thinnest and most uniform fiber with a diameter of 0.9 µm and a diameter coefficient variation of 15% was obtained at an air temperature of 25°C under an air flow rate of 15 NL min^?1. This fiber also had a minimum of decreased molecular weight. POLYM. ENG. SCI., 54:2605–2609, 2014. © 2013 Society of Plastics Engineers     

Autophagic Cell Death and Cancer

Programmed cell death (PCD) is a crucial process required for the normal development and physiology of metazoans. The three major mechanisms that induce PCD are called type I (apoptosis), type II (autophagic cell death), and type III (necrotic cell death). Dysfunctional PCD leads to diseases such as cancer and neurodegeneration. Although apoptosis is the most common form of PCD, recent studies have provided evidence that there are other forms of cell death. One of such cell death is autophagic cell death, which occurs via the activation of autophagy. The present review summarizes recent knowledge about autophagic cell death and discusses the relationship with tumorigenesis.     

Low-temperature selective reduction of NO with propene over alkaline-exchanged mordenites

Partially protonated alkaline mordenites showed higher activity per acid amount below 573 K than acidic zeolites for the selective reduction of NO with C₃H₆ in the presence of O₂, which can be related to a high concentration of NO₃ ^- species in the zeolite channels. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of cell structure on oil absorption of highly oil absorptive polyurethane foam for on-site use

This article reports the effect of cell structure on oil absorption of highly oil-absorptive polyurethane foam (ON-PUR), which is suitable for on-site foaming. We have developed ON-PUR as an oil absorbing polyurethane foam using a very reactive recipe. ON-PUR was synthesized by mixing polyol, water, additives, and polymeric diphenylmethane diisocyanate (P-MDI) using a high-pressure foaming machine. Density, airflow, oil absorption of this foam, and cell structure by microscopy were measured. From these results, it was found that the airflow of this foam increased by crushing, and the oil absorption of this foam increased sharply in a narrow airflow range (from 0.1 to 0.8 scfm). This increase is estimated to be due to the decrease of closed cell structures by crushing treatment. Furthermore, we constituted on-site foaming system in bench scale, which was expected to be applicable to on-site preparation of ON-PUR. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 179–186, 1997     

Effect of Seeding on Metal Ion Recovery from Wastewater by Reactive Crystallization of Metal Carbonates

Reactive crystallization for separation and recovery of divalent metal ions from wastewater using a semi‐batch crystallizer has been developed. In this process, metal carbonates are produced by reacting metal sulfate solution with sodium carbonate solution. Nickel and copper ions are crystallized under particular initial pH conditions but the product shapes are not regular. Consequently, sphere seeds have been used as nucleus‐generating agents and their growth mechanism has been examined. When providing a particular amount of seeds before crystallization, metal substances piled up on the surface of the seeds, maintaining the form sphere, and the production of fines was restricted. The metal removal rate through reactive crystallization was ～99.9 % on average. This operation proved to be suitable for application in industrial wastewater treatment and for recycling of metal materials.