Crosslinked acrylic pressure‐sensitive adhesives. II. Effect of humidity on the crosslinking reaction

The effect of humidity during storage on the crosslinking reactions of isocyanate groups was investigated with attenuated total reflectance Fourier transform infrared spectroscopy with pressure‐sensitive adhesives composed of poly[ethyl acrylate‐co‐(2‐ethylhexyl acrylate)‐co‐(2‐hydroxyethyl methacrylate)] as a base resin and polyisocyanate as a crosslinker. A peak‐resolving analysis of the amide II region revealed four bands. According to an analysis of the Fourier transform infrared spectra of the model compounds, these four bands were assigned to free urethane linkages, hydrogen‐bonded urethane linkages, free urea linkages, and hydrogen‐bonded urea linkages. As expected, storage under humid conditions led to the formation of free and hydrogen‐bonded urea linkages corresponding to the promotion of isocyanate consumption. Peak resolution of the amide II region was found to be a reasonable way of monitoring urethane and urea linkages during crosslinking reactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3039–3045, 2003     

Small increase of CR1 and CR3 by C5a-receptors on polymorphonuclear leukocytes in systemic lupus erythematosus

One of the anaphylatoxins, C5a, is known to increase the expression of the complement receptors, CR1 and CR3, on PMNs which play important roles in the phagocytosis. We measured the expression of these receptors before and after the stimulation with C5a and C5a-receptors (C5aR) on PMNs in patients with systemic lupus erythematosus (SLE). PMNs from 16 patients and 11 normal controls were tested. All the patients with SLE were administered with prednisolone orally and were in the inactive stage. The CR1 expression in SLE was significantly weak (p < 0.01) before and after stimulation with 4.55 nM (50 micrograms/ml) of C5a. There was no significant difference of CR3 expression before stimulation. However, after the stimulation with C5a, the increase of CR3 on PMNs from SLE was significantly small (p < 0.01). C5aR on PMNs showed no difference between the two groups. However, the expression of C5aR was significantly suppressed in patients treated with a high dosage of prednisolone (> = 10 mg/day) compared to those with a low dosage of prednisolone (< 10 mg/day). There was no significant difference of CR1 and CR3 expression between these groups. It is concluded that the increase of CR1 and CR3 on PMNs by C5a in small in SLE, of which impaired increase is not due to C5aR on PMNs, and that the expression of C5aR is suppressed by prednisolone.     

Synthesis and characterization of chitosan/poly(acrylic acid) polyelectrolyte complex

Polyelectrolyte complex based on chitosan and acrylic acid monomer by photoinitiated free‐radical polymerization in the absence of crosslinker showed a large transition in swelling in response to changes in pH of surrounding medium. Their ability to swell arises from polyelectrolyte interactions and molecular structure of the complex. The main properties of interest that related to the molecular structure, swelling volumes, glass transition temperature, and elastic modulus of the complex were investigated. The effect of water content, the only variable in the sample component, played an important role in molecular structure of the complex and as a consequence, the extent of intermolecular linkage, especially amide bonds which in turn governed the degree of swelling of the polyelectrolyte complex in this study. The decreased degree of swelling and higher temperature shift of glass transition temperature was found with increased water content, whereas increased modulus of elasticity of dry complex was found in lower water content of synthesis component. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1025–1035, 2002     

Multifocal ventricular tachycardia after resuscitation by direct current counter shock in a dog

Cardiac arrest occurred in a male Labrador Retriever dog weighing 27.8 kg during induction to anesthesia. Immediately after the failure of resuscitation by the external cardiac compression, thoracotomy was performed and open chest direct current (DC) counter shocks were applied with routine emergency medications. Then the dog recovered consciousness. Although cardiac rhythm just after resuscitation was sinus tachycardia with paroxysmal supraventricular tachycardia, multifocal ventricular arrhythmia occurred 2 hr after resuscitation. This arrhythmia might be the result from reversible cardiac lesions due to DC counter shock.     

Dynamic Mechanical Properties and Adhesive Strengths of Emulsion Polymer by Power Feed Technique, I

Dynamic mechanical properties and adhesive strengths of power feed copolymer and random copolymer synthesized using styrene or methyl methacrylate and n-butyl acrylate were investigated. Although the two systems were synthesized from the same raw materials, power feed copolymer had a very broad transition compared with random copolymer. This fact was explained by the fact that the system synthesized through power feed method was an alloy of copolymers which are a continuous series from monomer A rich copolymers to monomer B rich copolymers. The dynamic mechanical behavior of film cast from solution was almost the same as that of emulsion film, which indicated more extensive application of power feed copolymer. In the P(nBA/St) system, power feed copolymer maintained its adhesive strengths over a wide temperature range compared with random copolymer. The absolute value, however, was not so high. This was due to the low cohesive strengths of the films.     

Dynamic Mechanical Properties and Adhesive Joint Strengths of Emulsion Polymers Produced by Power Feed Technique. III. Adhesive Joint Strengths of Grafted Power Feed Copolymer

Power feed copolymers were synthesized using styrene and n-butyl acrylate through non-uniform feeding emulsion polymerization. Poly(vinyl alcohol) (PVA) was used as a protective colloid, onto which vinyl monomers were grafted. Power feed copolymer had a very broad glass transition temperature compared with random copolymer, even if grafting and/or crosslinking were introduced to the system. This tendency was almost the same as the non-grafted power feed copolymer where only low molecular weight surfactant was used.

Adhesive joint strengths of power feed copolymers were evaluated compared with random copolymers. In the case of usual linear power feed copolymer, the adhesive joint strengths were not higher than those of random copolymer, which was considered to be due to the lower film strengths of the power feed copolymer. Power feed copolymer having grafting showed slightly higher adhesive joint strengths over a wide range of temperatures than random copolymer. When crosslinking was introduced to the system, power feed copolymer showed much higher adhesive joint strengths over a wide temperature range.     

Effects of dietary lipids on daunomycin-induced nephropathy in mice: comparison between cod liver oil and soybean oil

Although it is well known that dietary lipids affect the course of glomerulonephritis in rats and humans, the precise mechanisms involved have not been fully elucidated. The aim of this study was to investigate the effects of different types of dietary lipids (fish oil and vegetable oil) on daunomycin (DM)-induced nephropathy in mice fed on soybean oil (SO) or cod liver oil (CLO). Urinary protein excretion, serum albumin, creatinine, total cholesterol, and TG were measured, and glomerular histological changes were evaluated. Antioxidant enzymes were also measured, along with the levels of lipid peroxide, GSH, thromboxane (Tx) B_2′ and 6-keto prostaglandin F_1α in renal cortical tissue. Dietary CLO significantly reduced urinary albumin excretion and ameliorated the histological changes induced by DM. The increase of tissue lipid peroxide levels seen in SO-fed mice was suppressed in CLO-fed mice, whereas CLO-fed mice showed higher GSH levels than SO-fed mice throughout the experiment. In addition, renal tissue GSH peroxidase activity was significantly higher at 72 h after DM injection in CLO-DM mice than in SO-DM mice. Both renal cortical TxB₂ and 6-keto PGF_1α levels were significantly lower in CLO-DM mice than in SO-DM mice. These results suggest that inhibition of oxidative damage by dietary CLO played an important role in the prevention of DM nephropathy in this mouse model. The effect of CLO was closely associated with the inhibition of Tx synthesis.     

Crosslinked acrylic pressure sensitive adhesives. 3. Effect of adherend on film formation

The reaction of isocyanate in pressure sensitive adhesive (PSA) films adhered on to various adherends having different surface tensions was monitored by depth profiling using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy.In the latter stages of crosslinking reaction, unreacted isocyanate and its derivatives exist more in the bulk of the PSA than in the interfaces between PSA and adherends which are Teflon sheet and PE film having relatively lower surface tensions. In the case of using stainless steel having relatively higher surface tension as adherend, opposite segregation was observed compared to Teflon and PE.From X-ray photoelectron spectroscopy (XPS), it was revealed that N atoms exist more in surface than in bulk when stainless steel is used as adherend. We conclude that polyisocyanates migrate in the PSA film in order to minimize the magnitude of interfacial free energy between the PSA and the adherend, which leads to the change of surface tension of PSA film.     

A content search system considering the activity and context of a mobile user

People routinely carry mobile devices in their daily lives and obtain a variety of information from the Internet in many different situations. In searching for information (content) with a mobile device, a user’s activity (e.g., moving or stationary) and context (e.g., commuting in the morning or going downtown in the evening) often change, and such changes can affect the user’s degree of concentration on his or her mobile device’s display and information needs. Therefore, a search system should provide the user with an amount of information suitable for the current activity and a type of information suitable for the current context. In this study, we present the design and implementation of a content search system that considers a mobile user’s activity and context, with the goal of reducing the user’s operation load for content search. The proposed system switches between two kinds of content search systems according to the user’s activity: the location-based content search system is activated when the user is stationary (e.g., standing and sitting), while a menu-based content search system is activated when the user is moving (e.g., walking). Both systems present information according to user context. The location-based system presents detailed information via menus and a map according to location-based categories. The menu-based system presents only a few options to enable users to get content easily. Through user experiments, we confirmed that participants could get desired information more easily with this system than with a commercial search system.     

Using anatomical knowledge expressed as fuzzy constraints to segment the heart in CT images

Segmenting the heart in medical images is a challenging and important task for many applications. In particular, segmenting the heart in CT images is very useful for cardiology and oncological applications such as radiotherapy. Although the majority of methods in the literature are designed for ventricle segmentation, there is a real interest in segmenting the heart as a whole in this modality. In this paper, we address this problem and propose an automatic and robust method, based on anatomical knowledge about the heart, in particular its position with respect to the lungs. This knowledge is represented in a fuzzy formalism and it is used both to define a region of interest and to drive the evolution of a deformable model in order to segment the heart inside this region. The proposed method has been applied on non-contrast CT images and the obtained results have been compared to manual segmentations of the heart, showing the good accuracy and high robustness of our approach.