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Pulsed ultrasound speeds tissue regeneration
The same tests were applied to the airborne-irradiated specimens as in the liquid phase-irradiated experiments, but no major fibre alteration was detected before the cellulose combustion began. Factors which governed fibre destruction by oxidation, or other means, in a high intensity acoustic field were investigated; one was the compactness of the fibre specimen. Fig 6 shows the influence of bulk density (compactness) of Acala 4-42 cotton specimens on conversion of sound into heat in air; the more compact specimens ignited at around 160°C and exhibited a linear temperature increase, while the temperatures of the more loosely packed specimens increased linearly for the first 100sec. At this point the rate decreased considerably. The next step was to relate the acoustic energy density to rate of sound conversion into heat, when irradiating cotton specimens of the some compactness.
ULTRASONIC CONTROL OF LEATHER SPRAYING New leather spraying machines, claimed to be the most upto-date in the world, have been designed and produced by Barrow Hepburn and Gale (Machinery) Ltd, of Leeds, Yorkshire, England. The machines incorporate Sonac ultrasonic
The results obtained show that sound-to-heat conversion proceeds at a faster rate in the mid-frequency range. Then, the irradiation of Acala 4-42 was carried out successively in air, oxygen and nitrogen, and the ignition threshold was a function of the concentration of oxygen. With pure oxygen combustion occurs at approximately 184”C, with air around 19Cf’C,and with nitrogen around 207°C. Finally, it was found that large amplitude low frequency sound waves were not powerful enough to shake loose a significant amount of trash and foreign particles contained in raw cotton samples. 1
Boucher, R.M.G., and Staples, M. ‘Sonic and ultrasonic irradiation of cotton fibers’, Textile Research Journal 3’7,8,621 (196’7)
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206
01 ’ 0 6
sensing devices (manufactured by Westool Ltd of Bishop Aukland, Co. Durham, England) to control the spraying of pigment onto leather. 26.5 ktiz high bulk density
The machines, which can deal with all normal hides, consist of a number of spray heads fitted to a rotating spider: two of the heads are shown in Fig ‘7, which also shows the two sensors fitted to each head. These are arranged so that when leather is passing beneath the head, the ultrasound beam is reflected from one sensor back to the other, and the resulting circuit triggers the pigment spraying mechanism. When there is no leather beneath any of the heads the spraying mechanism cannot operate. The frequency used is approximately 38kHz, and the normal voltage is 230V ac, but 15V ac is available when intrinsic safety is required.
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time I set
PULSED ULTRASOUND SPEEDS TISSUE REGENERATION
M. Dyson and J. Pond in the anatomy department of Guy’s Hospital Medical School, London, have found that epidermal and connective tissue regenerates up to 33% faster when the area is irradiated with pulsed ultrasound. Holes lcm square were made in each of the ears of a series of rabbits. The edges of the wound generally healed in about 14 days, after which regeneration began. In each of the rabbits the tissue around the hole in one ear was left to regenerate untreated. On average the untreated holes in the ears of male rabbits closed in about 50 days, and in females 70 days. The reason for this difference is uncertain. The hole in the other ear of each of the rabbits was subjected to pulsed ultrasound at 3.5MHz, 2ms on and 2ms off at intensities from 0.25-8W/cms. The investigators found the optimum intensity to be around 0.5W/cma. At this intensity the holes closed in male rabbits in about 34 days and in female rabbits in about 46 days. High intensities of 8W/cma caused damage. Ultrasound probably accelerates the migration of cells to the site of the injury, and probably also increases the rate of protein synthesis. It does not, however, increase the rate at which collagen is laid down, so the new tissue contains a smaller proportion of collagen and may have a reduced tensile strength.
The machines are claimed to reduce the wastage of pigment to a minimum; the manufacturers estimate that the new system has saved them SU?.,of the cost of chromate used and has led to a substantial increase in output. Unlike other control systems, the build-up of pigment on the sensor heads does not affect the operation of the machines.
SUBJECTIVE EFFECTS OF AIRBORNE NOISE FROM INDUSTRIAL SOURCES Ultrasonic frequencies are not responsible for subjective effects, such as fatigue, persistent headaches, nausea, and tinnitus. These effects were reported by personnel who worked near ultrasonic washers in a factory, and their complaints were investigated by W. I.Acton and M. B. Carsoni,
8 ULTRASONICS January 1968
7
ULTRASONIC CONTROL OF LEATHER SPRAYING New leather spraying machines, claimed to be the most upto-date in the world, have been designed and produced by Barrow Hepburn and Gale (Machinery) Ltd, of Leeds, Yorkshire, England. The machines incorporate Sonac ultrasonic
The results obtained show that sound-to-heat conversion proceeds at a faster rate in the mid-frequency range. Then, the irradiation of Acala 4-42 was carried out successively in air, oxygen and nitrogen, and the ignition threshold was a function of the concentration of oxygen. With pure oxygen combustion occurs at approximately 184”C, with air around 19Cf’C,and with nitrogen around 207°C. Finally, it was found that large amplitude low frequency sound waves were not powerful enough to shake loose a significant amount of trash and foreign particles contained in raw cotton samples. 1
Boucher, R.M.G., and Staples, M. ‘Sonic and ultrasonic irradiation of cotton fibers’, Textile Research Journal 3’7,8,621 (196’7)
r
206
01 ’ 0 6
sensing devices (manufactured by Westool Ltd of Bishop Aukland, Co. Durham, England) to control the spraying of pigment onto leather. 26.5 ktiz high bulk density
The machines, which can deal with all normal hides, consist of a number of spray heads fitted to a rotating spider: two of the heads are shown in Fig ‘7, which also shows the two sensors fitted to each head. These are arranged so that when leather is passing beneath the head, the ultrasound beam is reflected from one sensor back to the other, and the resulting circuit triggers the pigment spraying mechanism. When there is no leather beneath any of the heads the spraying mechanism cannot operate. The frequency used is approximately 38kHz, and the normal voltage is 230V ac, but 15V ac is available when intrinsic safety is required.
’ ’ ’ ’ ’ ’ ’ ’ ’ ’ ’ ’ ’
40
86
120
Irradiation
160
200
240
280
time I set
PULSED ULTRASOUND SPEEDS TISSUE REGENERATION
M. Dyson and J. Pond in the anatomy department of Guy’s Hospital Medical School, London, have found that epidermal and connective tissue regenerates up to 33% faster when the area is irradiated with pulsed ultrasound. Holes lcm square were made in each of the ears of a series of rabbits. The edges of the wound generally healed in about 14 days, after which regeneration began. In each of the rabbits the tissue around the hole in one ear was left to regenerate untreated. On average the untreated holes in the ears of male rabbits closed in about 50 days, and in females 70 days. The reason for this difference is uncertain. The hole in the other ear of each of the rabbits was subjected to pulsed ultrasound at 3.5MHz, 2ms on and 2ms off at intensities from 0.25-8W/cms. The investigators found the optimum intensity to be around 0.5W/cma. At this intensity the holes closed in male rabbits in about 34 days and in female rabbits in about 46 days. High intensities of 8W/cma caused damage. Ultrasound probably accelerates the migration of cells to the site of the injury, and probably also increases the rate of protein synthesis. It does not, however, increase the rate at which collagen is laid down, so the new tissue contains a smaller proportion of collagen and may have a reduced tensile strength.
The machines are claimed to reduce the wastage of pigment to a minimum; the manufacturers estimate that the new system has saved them SU?.,of the cost of chromate used and has led to a substantial increase in output. Unlike other control systems, the build-up of pigment on the sensor heads does not affect the operation of the machines.
SUBJECTIVE EFFECTS OF AIRBORNE NOISE FROM INDUSTRIAL SOURCES Ultrasonic frequencies are not responsible for subjective effects, such as fatigue, persistent headaches, nausea, and tinnitus. These effects were reported by personnel who worked near ultrasonic washers in a factory, and their complaints were investigated by W. I.Acton and M. B. Carsoni,
8 ULTRASONICS January 1968
7