Evaluation of removal of model particulate and oily soils from poly(ethylene terephthalate) films by microscopic image analysis.

The soil removal behavior from poly(ethylene terephthalate) (PET) films was investigated using a microscopic image analysis system. Carbon black or stearic acid as a model soil was deposited onto a PET film. The PET film was cleaned in various aqueous and non-aqueous solutions by applying stirring or frequency-modulated ultrasound as a mechanical action of soil removal. The amounts of soil deposited on the PET film before and after cleaning were obtained via binary processing of microscopic images, from which the removal efficiency was calculated. Most of the carbon black was deposited on the PET film as submicron aggregates and ultrasound removed them efficiently in a short time, even for relatively smaller aggregates. The removal efficiencies with stirring were less than ca. 10% in all solutions, whereas the removal using ultrasound had high efficiencies that exceeded 80% in the surfactant-free systems. In the case of stearic acid, the removal efficiency with stirring was below 30% in the aqueous solutions, although stearic acid was removed completely in ethanol and n-decane. For ultrasonic cleaning, the removal efficiencies of stearic acid in aqueous solutions became 2-3 times as large as those with the stirring action. To improve soil release in aqueous solutions, the PET film was treated by the dry processing using an atmospheric pressure plasma jet (APPJ) equipment. The wettability and the surface free energy of the PET film were found to increase due to surface oxidation via the APPJ treatment, which resulted in enhanced removal of carbon black and stearic acid in any aqueous solutions.

Osteoradionecrosis of the cervical vertebrae in patients irradiated for head and neck cancers.

Osteoradionecrosis (ORN) is one of the common late adverse effects that follow radiation therapy for head and neck cancers. ORN usually develops on the mandible and less frequently on the maxilla. We present three cases of ORN of the cervical vertebrae, which is rarely reported. Two patients suffered from secondary osteomyelitis after neoadjuvant chemotherapy followed by definitive concurrent chemoradiation therapy with a hyperfractionated and an accelerated hyperfractionated regimen, respectively. For these patients, the high intensity of treatment was considered the cause of ORN. The third patient underwent concurrent chemoradiation therapy for upper thoracic esophageal cancer and subsequently underwent endoscopic laser resection and radiation therapy for hypopharyngeal cancer. ORN developed in the area of reirradiation. In this case, an excessive radiation dose was considered the cause. ORN of cervical vertebrae, different from that of the mandible and maxilla, has a risk of radiculopathy and myelopathy. In the future, ORN of cervical vertebrae will increase because metachronous double cancers will increase and opportunities for reirradiation, in turn, will increase. To prevent this, it is necessary to optimize the treatment schedule for radiation therapy, including the total dose, fractionation, and concurrent chemotherapy, and to decrease the volume of cervical vertebrae within the irradiation field.

Removal of carbon black particles from polymer substrates in water/ethanol mixtures.

The removal of the carbon black (CB) particles from the polymer substrates was investigated in water/ethanol mixtures. As substrates, the films and the fibrous assemblies of polyethylene, nylon 6 and cellulose acetate were used. The ultrasonic wave was applied as a mechanical action for cleaning. The detergency of the CB particles for the films and the fibrous assemblies was assessed with the quartz crystal microbalance (QCM) technique and the reflectometry, respectively. The detergency for the films was discussed with the wetting force calculated from the experimentally determined contact angle on the substrate and surface tension of the water/ethanol mixture.

A quartz crystal microbalance simulation to examine the effect of ultraviolet light treatment on characteristics of polyethylene surface.

The effect of ultraviolet light irradiation on the characteristics of the polyethylene (PE) surface was investigated by the quartz crystal microbalance (QCM) technique. The PE film was prepared on the gold electrodes of the QCM by spin-coating from the solution and then was treated by the excimer UV lamp in ambient air. The changes in the hydrophilic properties, moisture adsorption, and water retention of the PE film due to the UV irradiation were determined from the frequency change of the QCM. To evaluate the detergency of the PE film, stearic acid as model oily soil was deposited onto the PE film formed on the QCM by the Langmuir-Blodgett (LB) technique, and was ultrasonically cleaned in aqueous detergent solutions containing ethanol or surfactant. The removal efficiency obtained from the frequency change of the QCM was found to increase considerably after the UV irradiation. From independently determined contact angles and the surface free energy components of the PE film, the free energy change resulting from the penetration of the detergent solution between stearic acid and PE in the zone of contact was calculated. Good relation was found between the removal efficiency and the free energy change, indicating that the increase in the detergency of the PE surface by UV irradiation was explained by surface energetics.