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This article reviews the recent applications of time-of-flight secondary ion mass spectrometry in the determination of surface structures of semicrystralline and amorphous polymer films. Examples given include the determination of end-group distributions on semicrystalline polymer surfaces, lamellar orientation on thin-film surfaces, the structures of the folds of lamellae, the morphologies of polymer blends, the relationship between film stability and the concentration of the end groups, and the structures of thin polymer films.

Blends of the alternating ethylene–tetrafluoroethylene copolymer (ETFE) with poly(vinylidene fluoride) (PVF2) were prepared by melt-mixing. Compatibility, morphology, thermal behavior, and mechanical properties of the ETFE/PVF2 blends with various compositions were studied by using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), tensile tests, and scanning electron microscopy (SEM). DMA studies showed that the blends have separate glass transition temperatures (Tg) close to those of the pure polymers. ETFE and PVF2 are incompatible. Marked negative deviations from simple additivity were observed for both the ultimate strength and the elongation at break over the entire composition range. The interfaces between ETFE and PVF2 are weakly bonded with rather poor interaction. SEM observations revealed that the blends have a two-phase structure and the adhesion between the phases is poor. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:295–304, 1997

Conductive polymer composites were prepared by sintering a mixture of ultrahigh molecular weight polyethylene (UHMWPE) powder and carbon black. Two processing parameters-time and temperature-were shown to have a notable effect on the resistivity of the composites. The relationships between the processing parameters and morphology were studied using optical microscopy and transmission electron microscopy (TEM). The results of the optical microscopy studies indicate that the carbon black is distributed in the interfacial regions between the UHMWPE particles. The dimension of the carbon black channels increases with the carbon black concentration. TEM micrographs show that a high degree of intermixing between the carbon black and the polymer occurs at higher temperatures and longer processing times, resulting in higher resistivities. A positive temperature coefficient (PTC) effect was observed for these materials. A mechanism for the PTC effect in this system is proposed. The magnitude of the PTC effect is found to be inversely proportional to the dimension of the carbon black channels in the composites. The dimension is directly related to the carbon black concentration. The PTC effect is a result of the polymer volume expansion caused by melting of the crystallites. A large PTC effect is observed for the composites with a low carbon black concentration and vice versa. No negative temperature effect (NTC) is observed at temperatures substantially above the melting point of the polymer.

The effect of a processing agent (Dynamar) on the viscosity and surface properties of high-density polyethylene (HDPE) has been studied. A capillary rheometer was used to measure the viscosity of HDPE compounds containing various concentrations of Dynamar as a function of time at constant apparent shear rates. The shear rates used are 250 and 500 sec−1. The addition of a small amount of Dynamar leads to a marked reduction in viscosity. The viscosity decreases dramatically initially, then levels off to an equilibrium. The rate of the viscosity reduction and the equilibrium viscosity value depend upon the Dynamar concentration and the shear rate. This phenomenon can be explained by the migration of Dynamar from the bulk to the interface of HDPE melt and die wall, resulting in the formation of a lubrication layer. X-ray photoelectron spectroscopy and scanning secondary ion mass spectrometry analyses of the extrudates from a slit die reveal a low concentration of Dynamar at the surface. Adhesive failure at the Dynamar and HPDE interface is attributed to a reduction in viscosity. © 1997 John Wiley & Sons, Ltd.

The rheological behavior of fluoroelastomer high-density polyethylene (HDPE) blends was investigated in detail. A capillary rheometer was used to determine the apparent viscosity of the blends as a function of time at various shear rates. The time to attain the steady state and the normalized steady-state apparent viscosity of the blends depend on shear rate and the fluoroelastomer concentration. The reduction in the apparent viscosity is caused by adhesive failure at the interface between the HDPE melt and the fluoroelastomer layer which was formed on the die wall surface during the extrusion of the blends. The presence of the fluoroelastomer layer on the die wall surface was confirmed by x-ray photoelectron spectroscopy and rheological measurements. Based on our previous work and this work, we have discovered that there are at least two different mechanisms—adhesive failure at the interface between the extrudate and the lubricating layer or cohesive failure in the lubricant layer—for viscosity reduction in polymer blends.

Blends of an alternating ethylene-tetrafluorethylene copolymer (ETFE) and poly(methyl methacrylate) (PMMA) were prepared by melt mixing in a mixer. Compatibility, thermal behaviour and morphology of the blends of various compositions were investigated by using dynamic mechanical analysis (d.m.a.), Fourier transform infra-red spectroscopy (FTi.r.), solid-state nuclear magnetic resonance (n.m.r.) spectroscopy, differential scanning calorimetry (d.s.c.) and wide-angle X-ray diffraction. D.m.a. and d.s.c. results show that the glass transition temperature (Tg) of the ETFE in the blends increases as the PMMA content increases and the Tg of the PMMA moves to low temperatures when the ETFE content increases. In addition, d.s.c. results indicate an additional Tg, which is located between the Tg of PMMA and that of ETFE. The presence of this additional Tg suggests the existence of one semicrystalline phase and two amorphous phases—an ETFE/PMMA phase and a PMMA-rich phase. D.s.c. results also indicate that the melting temperature of ETFE decreases while the crystallinity of ETFE increases slightly as the PMMA content increases. FTi.r. results show that the absorption peak of the carbonyl group of the PMMA in the blends stays almost at the same position as in the pure component. Solid-state n.m.r. results reveal that the changes in chemical shift of the carbonyl group of PMMA in the blends are less than 0.5 ppm. These results confirm that only weak interactions exist between ETFE and PMMA. X-ray diffraction results reveal that no new crystal forms appear in the blends. © 1997 Elsevier Science Ltd.

A blend of poly(epsilon-caprolactone) (PCL) and poly(vinyl chloride) (PVC) with 90 wt % PCL was prepared. Two films of this blend, which were grown at 35 and 45 degrees C, showed the absence and presence of banded spherulites, respectively. A detailed examination conducted with time-of-flight secondary ion mass spectrometry (ToF-SIMS) found that the surface composition of the film grown at 45 degrees C was related to its structure, which was shown to contain ridges and valleys. Phase images obtained using atomic force microscopy (AFM) indicated that the ridges and valleys consisted of edge-on and flat-on lamellae, respectively. ToF-SIMS imaging revealed that PVC and PCL were located mainly on the surface of the valleys and ridges, respectively. This morphology-driven surface segregation was caused by the difference in the surface energy between the flat-on and edge-on lamellae.

A novel process for preparation of conductive polypyrrole/poly(vinyl chloride) (PPy/PVC) composites by pre-localization of an intrinsically conducting PPy phase in a PVC matrix has been developed. This process involves encapsulating PVC particles with a thin layer of PPy, and subsequently compacting this PPy-encapsulated PVC powder by compression molding. The current-voltage characteristics and electrical conductivity of the pre-localized PPy/PVC composites were determined. The change of the current-voltage characteristics from linear to nonlinear behavior with increasing PPy content in the composites is discussed in the view of the intermolecular hopping and tunneling of electrons. The tensile properties, dynamic mechanical behavior, and microhardness of the pre-localized PPy/PVC composites were studied as a function of PPy content. A percolation threshold of 0.3 wt% is achieved in the pre-localized PPy/PVC composites. This value is much lower than those of the conventional conductive composite materials containing a random distribution of PPy fillers. The samples with a PPy content of 1.6 wt% or above have high conductivity and still preserve reasonable mechanical properties.

Polymers have been applied successfully in fields such as adhesion, biomaterials, protective coatings, friction and wear, composites, microelectronic devices, and thin-film technology. In general, special surface properties with regard to chemical composition, hydrophilicity, roughness, crystallinity, conductivity, lubricity, and cross-linking density are required for the success of these applications. Polymers very often do not possess the surface properties needed for these applications. However, they have excellent bulk physical and chemical properties, are inexpensive, and are easy to process. For these reasons, surface modification techniques which can transform these inexpensive materials into highly valuable finished products have become an important part of the plastics and many other industries. In recent years, many advances have been made in developing surface treatments to alter the chemical and physical properties of polymer surfaces without affecting bulk properties. Common surface modification techniques include treatments by flame, corona, plasmas, photons, electron beams, ion beams, X-rays, and γ-rays. Plasma treatment is probably the most versatile surface treatment technique. Different types of gases such as argon, oxygen, nitrogen, fluorine, carbon dioxide, and water can produce the unique surface properties required by various applications. For example, oxygen-plasma treatment can increase the surface energy of polymers, whereas fluorine-plasma treatment can decrease the surface energy and improve the chemical inertness. Cross-linking at a polymer surface can be introduced by an inert-gas plasma. Modification by plasma treatment is usually confined to the top several hundred angstroms and does not affect the bulk properties. The main disadvantage of this technique is that it requires a vacuum system, which increases the cost of operation. Thin polymer films with unique chemical and physical properties are produced by plasma polymerization. This technology is still in its infancy, and the plasma chemical process is not fully understood. The films are prepared by vapor phase deposition and can be formed on practically any substrate with good adhesion between the film and the substrate. These films, which are usually highly cross-linked and pinhole-free, have very good barrier properties. Such films find great potential in biomaterial applications and in the microelectronics industry. Very high-power microwave-driven mercury lamps are available, and they are used in UV-hardening of photoresist patterns for image stabilization at high temperatures. Other applications of UV irradiation include surface photo-oxidation, increase of hydrophilicity, and photocuring of paintings. Pulsed UV-lasers are used in surface modification in many areas. Pulsed UV-laser irradiation can produce submicron periodic linear and dot patterns on polymer surfaces without photomask. These interference patterns can be used to increase surface roughness of inert polymers for improved adhesion. These images can also be transferred to silicon surfaces by reactive ion etching. Pulsed laser beams can be applied to inert polymer surfaces for increased hydrophilicity and wettability. Polymer surfaces treated by pulsed UV-laser irradiation can be positively or negatively charged to enhance chemical reactivity and processability. Pulsed UV-laser exposures with high fluence give rise to photoablation with a clean wall profile. There are many other practical applications of laser photoablation, including via-hole fabrication, and diamond-film deposition. The present review discusses all these current applications, especially in the biomedical and microelectronics areas.

A novel method was developed for the preparation of high-resistivity conductive polymer composites reproducibly. The conventional method which involves the simple mixing of a conductive filler and a polymer usually produces a conductive polymer composite having a loading curve with a region in which the resistivity changes rapidly as the filler concentration changes. Hence, it is very difficult to obtain reproducible materials in that region. This newly developed method involves the preparation of a conventional conductive polymer composite, which is prepared by the simple mixing of carbon black and a polymer as the first step. The resulting compound, which is crosslinked by either electron-beam radiation or a chemical-crosslinking agent, is ground into a fine powder (composite filler) with the particle size less than 250 microns. The composite filler is mixed with another polymer to form a conductive particulate composite which has a loading curve showing a more gradual change of resistivity as a function of filler concentration. The modification of the loading curve is controlled by the resistivity, the shape, and the size of the composite filler.

A new kind of thermoplastic elastomer is obtained by dynamic curing of PVC/SBR blends. A compatibilizer is necessary, and of three tested—NBR and two ABSs—NBR-18 is the best. Sulfur and Dicumyl peroxide were chosen as the two different curing agents for the blends. The curing agent and its concentration have a dramatic effect on the mechanical properties. Di(2-ethyl hexyl)phthalate was used as the plasticizer for PVC. Variations in the PVC and di(2-ethyl hexyl)phthalate concentrations can produce materials having a wide range of hardness and strength to meet the needs of different applications. The effects of processing parameters such as blending time and processing temperature and the effect of filler in the blend on the mechanical properties were also investigated. The material, after processing five times, showed no significant changes in physical properties. © 1995 John Wiley & Sons, Inc.

The effects of the die-wall material on the apparent viscosity of a blend of Hytrel and Viton and on the formation of a particle-like material, which is commonly referred to as die drool, at the polymer-metal interface were studied. The blend, which consisted of approximately 15 % Viton and 85 % Hytrel, was prepared by using a twin-co-rotating-screw extruder. During extrusion of this blend, small particles appeared on the surface of the extrudates; these particles were determined by XPS to be a material which consisted largely of Viton. The apparent viscosity of the blend and the amount of die drool were found to decrease as the surface energy of the material used for the construction of the die decreased. The reduction in the production rate of die drool is attributed to reduction of adhesion at the interface.

Purpose In diseases such as proliferative vitreoretinopathy (PVR), proliferative diabetic retinopathy, and age-related macular degeneration, retinal pigment epithelial (RPE) cells proliferate and migrate. Moreover, platelet-derived growth factor (PDGF) has been shown to enhance proliferation and migration of RPE cells in PVR. Even resveratrol can suppress the migration and adhesion of many cell types, its effects on RPE cell migration and adhesion remain unknown. In this study, we investigated the inhibitory effects of resveratrol on RPE cell migration induced by PDGF-BB, an isoform of PDGF, and adhesion to fibronectin, a major ECM component of PVR tissue. Methods The migration of RPE cells was assessed by an electric cell-substrate impedance sensing migration assay and a Transwell migration assay. A cell viability assay was used to determine the viability of resveratrol treated-cells. The cell adhesion to fibronectin was examined by an adhesion assay. The interactions of resveratrol with PDGF-BB were analyzed by a dot binding assay. The PDGF-BB-induced signaling pathways were determined by western blotting and scratch wound healing assay. Results Resveratrol inhibited PDGF-BB-induced RPE cell migration in a dose-dependent manner, but showed no effects on ARPE19 cell adhesion to fibronectin. The cell viability assay showed no cytotoxicity of resveratrol on RPE cells and the dot binding assay revealed no direct interactions of resveratrol with PDGF-BB. Inhibitory effects of resveratrol on PDGF-BB-induced platelet-derived growth factor receptor β (PDGFRβ) and tyrosine phosphorylation and the underlying pathways of PI3K/Akt, ERK and p38 activation were found; however, resveratrol and PDGF-BB showed no effects on PDGFRα and JNK activation. Scratch wound healing assay demonstrated resveratrol and the specific inhibitors of PDGFR, PI3K, MEK or p38 suppressed PDGF-BB-induced cell migration. Conclusions These results indicate that resveratrol is an effective inhibitor of PDGF-BB-induced RPE cell migration via PDGFRβ, PI3K/Akt and MAPK pathways, but has no effects on the RPE cell adhesion to fibronectin.

This chapter describes the use of calcium carbonate nanoparticles in polymers. The chapter first reviews the production of calcium carbonate nanoparticles and their surface treatments. The chapter then reviews various polymer nanocomposites. Finally, it presents the toughening mechanisms of polymers filled with calcium carbonate nanoparticles.

High-impact polystyrene (PS) nanocomposites filled with individually dispersed halloysite nanotubes (HNTs) were prepared by emulsion polymerization of styrene in the presence of HNTs with sodium dodecyl sulfate (SDS) as the emulsifier. The SDS is a good dispersing agent for HNTs in aqueous solution. The emulsion polymerization resulted in the formation of polystyrene nanospheres separating individual HNTs. Transmission electron microscopy revealed that the HNTs were uniformly dispersed in the PS matrix. Differential scanning calorimetry, Fourier-transform infrared spectroscopy and thermogravimetry were used to characterize the PS/HNT nanocomposites. The impact strength of the PS/HNTs nanocomposites was 300% higher than that of the neat PS. This paper presents a simple yet feasible method for the preparation of high-impact PS/halloysite nanocomposites.

The effects of a low‐surface‐energy component, polytetrafluoroethylene (PTFE), on the apparent viscosity of poly(ether ether ketone) (PEEK) were studied. Blends of PEEK and PTFE were prepared by using a twin‐counter‐rotating‐screw extruder (ZSE). One percent and five percent by weight of PTFE were used. The apparent viscosity of the blends as a function of apparent shear rate was determined by a capillary rheometer. The observed reduction in the apparent viscosity is attributed to the migration and accumulation of the low‐surface‐energy component (PTFE) at the interface between the die wall and the melt. The enrichment of PTFE on the surface of the extrudates was confirmed by x‐ray photoelectron spectroscopy. Surface enrichment of PTFE and viscosity reduction are enhanced with an increase in shear rate and PTFE concentration in the blend.

Since polymer spherulites were observed using optical microscopy and single polymer crystals were prepared from solution,1,2 the internal structure of polymer spherulites has been investigated widely with electron microscopy.3-9 For most crystalline polymers, it is generally accepted that spherulites are developed from a single crystal through unidirectional growth, and the spherical shape is attained through continuous splaying apart and occasional branching of lamellae,5 though there are ongoing debates concerning the details of the branching in the literature. More recently, atomic force microscopy (AFM) has been utilized to study the organization of spherulites and the crystallization process of polymers.10,11 A copolymer, poly(bisphenol A-co-octane),12 was synthesized with the following structure

Purpose Oxidative injury to the retinal pigment epithelium (RPE) has been proposed to play a contributing role in age-related macular degeneration (AMD). Exposure to solar ultraviolet (UV) radiation is believed to cause the production of reactive oxygen species (ROS), which may cause oxidative damage to RPE cells. Studies have shown that (-)-epigallocatechin gallate (EGCG), an abundant and active component in green tea, can protect several cell types from oxidative stress. It may be useful in the prevention of early AMD. Methods To determine whether EGCG protects RPE cells from UVA-induced damage, we used a cell viability assay to determine the viability of UVA-treated cells. Intracellular H2O2 levels were measured by flow cytometry. Western blotting was used to detect UVA-induced signaling pathways. Results The results indicated that EGCG inhibits UVA-induced RPE cell death. In addition, intracellular H2O2 generation in RPE cells irradiated by UVA was inhibited by EGCG in a concentration-dependent manner. EGCG also inhibited UVA-induced extracullar signal-regulated kinase (ERK) and c-jun-NH2 terminal kinase (JNK) activation in RPE cells while a higher concentration of EGCG had an inhibitory effect on UVA-induced p38 activation. Finally, we investigated cyclooxygenase-2 (COX-2) expression in RPE cells exposed to UVA radiation, and EGCG was found to also have inhibited UVA-induced COX-2 expression. Conclusions Taken together, our results demonstrate that EGCG inhibits UVA-induced H2O2 production, mitogen-activating protein kinase activation, and expression of COX-2. Moreover, it enhances RPE cell survival after UVA exposure. This suggests EGCG is effective in preventing UVA-induced damage in RPE cells and may be suitable for further developments as a chemoprotective factor for the primary prevention of early AMD.

Myricetin is a flavonoid similar to quercetin, which is commonly found in natural foods such as berries, vegetables, teas, wine, and herbs. It is considered to be an antioxidant which is capable of quenching photoaging-causing free radicals within the skin. In this study, we investigated the mechanisms underlying protective effect of myricetin on ultraviolet-B (UVB)-induced damage to keratinocytes. We found that myricetin concentration-dependently attenuated UVB-induced keratinocyte death as determined by a cell viability assay. Pretreatment with myricetin also reduced the UVB-induced malondialdehyde level. Moreover, UVB-induced H2O2 generation in keratinocytes was inhibited by myricetin according to flow cytometry, suggesting that myricetin can act as a free radical scavenger when keratinocytes experience photodamage. Furthermore, UVB-induced activation of c-jun-NH2 terminal kinase (JNK) in keratinocytes was inhibited by myricetin. UVB-induced pre-G1 phase arrest leading to apoptotic changes in keratinocytes was blocked by myricetin. Taken together, the protective mechanisms of keratinocyte by myricetin against UVB-induced photodamage occur by the inhibition of UVB-induced intracellular hydrogen peroxide production, lipid peroxidation and JNK activation. Therefore, myricetin is suitable for further development as an anti-aging agent for skin care.

The reversible transitions of the lamellae of a crystalline-crystalline diblock copolymer from the melt to crystallites were studied using simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) measurements with synchrotron radiation. A symmetric poly(ethylene oxide)-poly( $ \varepsilon$ -caprolactone) diblock copolymer was chosen for this study. We showed in the course of the block copolymer crystallisation that the time-resolved integrated intensity I int was proportional to the product of the volume fractions of the PEO and PCL phases and the scattering contrast due to the electron density difference. These results demonstrated that simultaneous SAXS/WAXS measurements could be used to monitor the crystallisation process in two domains of different sizes at the same time.

The water contact angle and self-cleaning property of microfabricated surface textures possessing different topologies are compared. In one kind of surface textures, the protruded regions form a connected square network. In the other kind of surface textures, the protruded regions form a regular array of square posts. We find that the water apparent contact angle of the connected textures agrees with the Cassie equation [Discuss. Faraday Soc. 3, 11 (1948)], but that of the disconnected textures is much larger. Nevertheless, the disconnected textures exhibit inferior self-cleaning property, contrary to conventional conception. We discuss the possible reasons for these observations.

BACKGROUND Epigallocatechin-3-gallate (EGCG) is the most potent antioxidant of all the green tea catechins. The objective of the present study was to find out whether it improved the age-induced hemorheological abnormalities or not. METHODS AND RESULTS Twenty-four-month-old aging guinea pigs were used to test the effects of EGCG on hemorheological properties. Orally feeding EGCG at 30 mg x kg(-1) x day (-1) for 28 days resulted in a decrease in erythrocyte membrane malondialdehyde, and further improved erythrocyte deformability and blood viscosity at high and middle shear rates. In addition, it also significantly reduced erythrocyte aggregation, and improved blood viscosity at low shear rates and viscoelasticity at oscillatory flow. Consequently, efficiency of blood oxygen transport in aged guinea pigs increased after administration with EGCG. CONCLUSIONS Orally feeding EGCG 30 mg x kg(-1) x day(-1) for 28 days significantly improves the abnormal hemorheological parameters. These results suggest that EGCG has considerable potential as a substantial component for the development of new drugs or functional foods in improving the age-induced hemorheological abnormalities.

Novel polymer crystalline structures containing micrometer-sized concentric rings (or bands) were observed in thin poly(bisphenol A hexane ether) (BA-C6) films. The origin of the banded structures was found to be different from that of traditional banded spherulites in polymer systems. Analyses based on optical microscopy (OM) and atomic force microscopy (AFM) revealed that the banded structures contained alternating ridge and valley bands of polymer crystals in the flat-on orientation. No lamellar twisting was observed within the concentric-ringed structures, which were developed as a result of the formation of a depletion zone during crystallization. The formation of a depletion zone was determined to be caused by the specific volume decrement between the crystal and the melt and by the diffusion of polymer chains to the fold surfaces of the flat-on lamellae. The height of the ridges and the interband widths could be adjusted by controlling the diffusion rate. Time-of-flight secondary ion mass spectrometry ion images showed higher concentrations of low-molecular-weight polymer chains on the surfaces of the ridges than in the valleys.

The results of XPS and 13 C NMR analyses suggest that surface segregation of the lower surface energy segment (BD) of the poly(acrylonitrile-co-butadiene)s occurs only when the butadiene segment length is at least equal to the length of the BBB triad segments and the BBB intensity is above a certain value

Branching of edge-on lamellae of poly(bisphenol A octane ether) (BA-C8) was studied at room temperature (21 +/- 1 degrees C) using real-time tapping mode atomic force microscopy (AFM). Lamellar branches were shown to develop from induced nuclei that had originated from lamellar defects, namely protruding cilia and loose loops, of parent lamellae. Induced nuclei appeared and also disappeared-a phenomenon observed first time by AFM. Induced nuclei are one of the possible origins for the branching of lamellae. Branching of edge-on lamellae can be induced by an AFM tip though the adjustment of the set-point amplitude ratio (r(sp)). Using an r(sp) smaller than 0.65, defects could be created on the lamellar surface, which gave rise to lamellar branches.

The process by which store-operated Ca2+ channels (SOCs) deliver Ca2+ to the endoplasmic reticulum (ER) and the role of (Ca2++Mg2+)ATP-ases of the ER in the activation of SOCs in H4-IIE liver cells were investigated using cell lines stably transfected with apo-aequorin targeted to the cytoplasmic space or the ER. In order to measure the concentration of Ca2+ in the ER ([Ca2+]er), cells were pre-treated with 2,5-di-tert-butylhydroquinone (DBHQ) to deplete Ca2+ in the ER before reconstitution of holo-aequorin. The addition of extracellular Ca2+ (Cao2+) to Ca2+-depleted cells induced refilling of the ER, which was complete within 5 min. This was associated with a sharp transient increase in the cytoplasmic Ca2+ concentration ([Ca2+]cyt) of about 15 s duration (a Cao2+-induced [Ca2+]cyt spike) after which [Ca2+]cyt remained elevated slightly above the basal value for a period of about 2 min (low [Ca2+]cyt plateau). The Cao2+-induced [Ca2+]cyt spike was inhibited by Gd3+, not affected by tetrakis-(2-pyridymethyl) ethylenediamine (TPEN), and broadened by ionomycin and the intracellular Ca2+ chelators BAPTA and EGTA. Refilling of the ER was inhibited by caffeine. Neither thapsigargin nor DBHQ caused a detectable inhibition or change in shape of the Cao2+-induced [Ca2+]cyt spike or the low [Ca2+]cyt plateau whereas each inhibited the inflow of Ca2+ to the ER by about 80%. Experiments conducted with carbonyl cyanide m-chlorophenyl-hydrazone (CCCP) indicated that thapsigargin did not alter the amount of Ca2+ accumulated in mitochondria. The changes in [Ca2+]cyt reported by aequorin were compared with those reported by fura-2. It is concluded that (i) there are significant quantitative differences between the manner in which aequorin and fura-2 sense changes in [Ca2+]cyt and (ii) thapsigargin and DBHQ inhibit the uptake of Ca2+ to the bulk of the ER but this is not associated with inhibition of the activation of SOCs. The possible involvement of a small sub-region of the ER (or another intracellular Ca2+ store), which contains thapsigargin-insensitive (Ca2++Mg2+)ATP-ases, in the activation of SOCs is briefly discussed.

This paper examines China’s compliance decisions of global infectious disease control in the cases of Severe Respiratory Acute Syndrome (SARS). The processes involve interactions of actors in various levels such as states, sub-state actors, and international actors. Although all states share the interests of a disease-free world, the consequences of national compliance on disease control processes are always costly and political. Why does a state comply with international standards mainly issued by World Health Organization (WHO) on infectious disease control? The paper looks into the politics of global infectious disease control by investigating the processes of China’s compliance decisions regarding SARS. More importantly, the paper addresses the political implications of compliance politics for China’s on global health crises.

Publisher Summary This chapter describes an experiment in which the electrical properties and morphology of a carbon black (CB)-filled immiscible blend of poly(vinylidene fluoride) (PVDF) and high density polyethylene (HDPE) were studied. The electrical conductivity of the composites increased dramatically when the CB content attained the percolation threshold approximately at a 0.035 volume fraction of CB. In addition to the CB content, the PVDF/HDPE volume ratio also affects the electrical conductivity of the composites. The electrical conductivity of the composites increased rapidly after the PVDF/HDPE volume ratio became greater than 0.17. The increase became more gradual when the PVDF/HDPE volume ratio was greater than 0.43. The results suggest that a decrease in HDPE content significantly increases the conductivity of the composites. The positive temperature coefficient (PTC) effect of the composites is caused by the thermal expansion because of the melting of the HDPE phase in the composites.

Polypropylene (PP) is a polymer with good mechanical properties which has been used in a wide range of applications. However, due to its inertness and low surface energy, PP has to be surface treated for applications in coatings, bonding, printing and metallization. The frequently used surface treatments for PP include plasma, corona and flame treatments. Plasma treatment of polymer surfaces has been studied extensively for many years [1]; however, it has not been used as extensively as corona and flame treatment in industry. Plasma treatments must be carried out in a vacuum and the cost of industry-scale equipment for such treatment is very high. The process parameters are highly system-dependent; the optimal processing conditions developed for one system usually cannot be adopted by another system.

Publisher Summary This chapter discusses the electrical properties of carbon black (CB)-filled polypropylene/ultrahigh molecular weight polyethylene (PP/UHMWPE) composites. In the experiment described in the chapter, CB-tilled PP/UHMWPE composites were prepared by the conventional melt mixing method. The electrical properties of the composites including the positive temperature coefficient (PTC) effect and the CB distributions in the PP/UHMWPE matrix are studied in the chapter. The results indicate that the PP/UHMWPE weight ratio and CB content are the two main factors that can significantly influence the electrical resistivity of the CB-filled PP/UHMWPE composites. At a fixed CB content, a minimum value in resistivity was observed at the PP/UHMWPE weight ratio of 1:1. At a fixed PP/UHMWPE weight ratio (1:1), a percolation threshold of 0.008 volume fraction of CB was observed, which is much lower than that of conventional CB-filled polymer composites. The measurements of resistivity of the composites versus temperature show that the stronger double-PTC effects are observed at low CB content and low PP/UHMWPE weight ratio. The melting of UHMWPE crystallites at about 140 °C and the melting of PP crystallites at about 170 °C were responsible for the first PTC effect and the second PTC effect, respectively. The results of optical microscopy studies illustrate that CB particles are selectively localized at the interface between the PP matrix and the UHMWPE particles or in the PP matrix because of the extremely high viscosity of UHMWPE.

Polymers such as polyethylene, polypropylene and polystyrene are very inert and have quite low surface energies. Therefore it is necessary to treat the surfaces of these polymers prior to processes such as printing or bonding [1]. Corona and flame treatments are commonly used in the industry to improve bondability and printability of polyolefin films and large-size objects because of the speed and ease of processing. The set-up for such an operation is very simple and cost-effective. A corona treatment system consists of an electrode connected to a high-voltage source and a grounded roll as shown in Figure 1. The grounded roll is usually covered with an insulating material such as polyester, ceramic, epoxy or silicon rubber. The corona occurs when a high voltage is applied across the electrodes to cause ionization of air. A plasma is formed and a light blue color can be observed in the air gap. This atmospheric pressure plasma is called a corona discharge. The insulating material, which covers the grounded roll, prevents a direct arc between the two electrodes. However, the roll covering material is subjected to damage due to heat and the corona. One of the solutions to this problem is resolved by using a quartz tube filled with irregularly shaped metal pellets as the electrode. Quartz, being impervious to damage by heat or corona, is a good material for this application. To control the environment in which the corona is generated, the corona equipment can be placed in a chamber that is continuously flushed with dried or humidified air.

We have given a brief overview of our recent studies of polymer crystallization using AFM. We believe that AFM will be a most important tool for investigating the crystalline structure of polymers in the near future. The in situ probing of the following processes, such as crystallization, melting, re-crystallization, etc., will provide us an opportunity to get a better understanding of polymer crystallization processes. The detailed investigation of the morphological changes of semi-crystalline polymers will provide more and more experimental results for the development of the polymer crystallization theory.