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In this in vitro study we investigated the influence of ionizing gamma rays on the stability in the region of the dentinoenamel junction. We removed the enamel on the labial surface of 30 incisors of bovines up to the dentinoenamel junction, so that a circular area of enamel with a diameter of 2.0 +/- 0.1 mm was left and an enamel cylinder was created. 15 teeth were irradiated by a cobalt-60-source (energy dose 70 Gy). The other 15 teeth were used as controls. Using a material testing apparatus the shear bond strengths were measured by breaking off the enamel cylinders. Furthermore, the breaking modes were investigated in SEM. Comparing the results of the shear bond strength experiments, it was obvious that the stability in the region of the dentinoenamel junction was significantly less among the irradiated teeth than among the non-irradiated teeth. The median value of the gamma ray treated teeth was x = 19.1 MPa and that of the non-ray-treated teeth was x = 37.4 MPa. The non-irradiated teeth showed fractured surfaces only in dentin in 10 cases and in 5 cases in both dentin and enamel. In contrast to that, the irradiated teeth had fractured surfaces in 12 cases exclusively in dentin and only in 3 cases the enamel was also fractured. These results lead us to conclude that changes of biophysical property of teeth can be caused by the influence of ionizing rays.

Numerous reviews of the principal photobiologic interactions between radiation and living tissues have been presented for the optical part of the electromagnetic radiation spectrum.1–7 In the specific case of laser radiation, the unique characteristic of monochromaticity of the incident field and the spatial and temporal coherence of the emission, find increasing use in medical applications, in both diagnosis and therapy. Together with the resulting biologic response of the irradiated tissues, these characteristics determine the specific modes of interaction, namely, the various processes of conversion of the incident electromagnetic energy within biomolecules.

Patients (142) with advanced gastrointestinal (GI) cancers were treated by photodynamic therapy (PDT) from September 1982 to December 1988. Haematoporphyrin derivative (HpD) (5 mg kg−1) was intravenously given 48–72 h prior to PDT. The light source was an argon dye laser emitting at 630 nm. The entire tumour was irradiated with a light dose of 100–250 J cm−2. Fifteen patients (10.6%) showed complete response (CR), 53 (37.3%) showed partial response (PR) and 32 (22.5%) showed mild response (MR). The clinical results show that the estimated energy dose (EED) of 200–250 J cm−2 is appropriate. All patients were treated by PDT and adjuvant chemotherapy showing good results with a follow-up of 1–5 years; 13 out of 15 patients in the CR group are alive (86.7%); 12 patients survived more than 2 years (8.8%).

A design method and experimental results for a direct-contact circular aperture applicator are provided. The aperture is excited in the TE/sub 11/ mode; a corrugated flange surrounding the aperture improves the uniformity of the heating pattern and limits leakage. The performance of the applicators operating in the S band (2.45 GHz) and the X band (9.96 GHz) has been tested using a short monopole probe and a thermographic camera. The heating patterns obtained by the two methods are in agreement within the experimental errors. The applicators are suitable for clinical use, as they are lightweight and rugged, and capable of delivering a desired energy dose effectively, thanks to a relatively small standing-wave ratio (SWR < 2) and very low leakage.

The threshold energy and current required for ventricular defibrillation was determined in dogs ranging in weight from 6.4 to 38 kg and in ponies ranging in weight from 40 to 101 kg. Trapezoidal waves, 10 ms in duration, with 10%, 50%, 70%, and 90% tilt were applied to transchest electrodes. For all values of tilt, the energy and current required increased with body weight. The energy dose (joules per kilogram of body weight) was higher for the heavier animals, whereas the current dose (peak amperes per kilogram of body weight) was essentially the same for dogs and ponies. In both species and for all four waveforms, the percent success increased with increasing energy and current dose. For all four waveforms and for both species, the threshold average current required for defibrillation was between 0.38 and 0.48 A/kg, indicating that average current may be a convenient unit to compare the efficacy of different waveforms.

Inferences regarding the mechanism of “microwave hearing” heretofore have been based upon theoretical studies, reports of human observers, animal behavioral experiments, and the recording of auditory field potentials. To gain more insight into the phenomenon we have examined the effect of pulsed microwave radiation (MWR) at 915 MHz on single auditory neurons in the cat. The responses to pulsed acoustic stimuli (“clicks”) and to pulsed MWR were compared by means of post-stimulus time histograms. Although the response to MWR was dependent upon parameters of the pulse of incident MWR, it was independent of the averaged rate of energy absorption. Threshold effects were observed at an energy dose as low as 4 μJ/g per pulse. Auditory units with characteristic frequencies (CFs) below 1.2 kHz appeared to be more responsive to pulsed MWR than were units with higher CFs. Many neurons demonstrated a response to pulsed MWR that was similar to the response to acoustic clicks, which may provide a means by which to define the acoustic equivalent of MWR. Our results support the view that microwave hearing is mediated, at least in part, by an electromechanical interaction that is initiated distal to the cochlea.

The relationship between myocardial lactate metabolism and the energy dose of direct countershock was studied in 15 dogs anesthetized with halothane. Five dogs received two shocks of 5 joules delivered energy each, five animals received two shocks of 10 joules delivered energy each, and five dogs received two shocks of 20 joules delivered energy each. All animals had positive myocardial lactate extraction in the baseline state (5 joules, 38% +/- 23.7 (SD); 10 joules, 59.6% +/- 11.4; 20 joules, 38% +/- 11.1). Lactate extraction after countershock progressively decreased with increasing energy dose and then returned to baseline. The maximal reduction in percent lactate extraction increased with increasing energy dose (5 joules, 13.9% +/- 16.1; 10 joules, 33% +/- 37; 20 joules, 30.5% +/- 37.5) and seemed to reach a threshold below which no further decrease occurred. Myocardial damage, as measured by a damage index derived from myocardial uptake of technetium-99 pyrophosphate, increased steadily with increasing energy dose (2.0 +/- 2.5 with 5-joule shocks; 38 +/- 32 with 10 joules; and 99 +/- 70 with 20 joules). These results show a consistent reduction in aerobic metabolism immediately following electric countershock. Even at low-energy doses, myocardial lactate extraction showed a detectable decrease and at higher energies approached net lactate production. Reductions of global lactate extraction did not completely predict the amount of myocardial damage. Localized measures of anaerobic metabolism or mitochondrial function might provide a better correlation with localized damage.

Experimental data on track widths in nuclear emulsion are compared with the theoretical distribution of the energy dose around the path of a moving ion. The dose distribution has been calculated following the formalism of the track formation theory developed by Katz and co-workers. The track widths have been estimated from light absorption profiles of heavy ion tracks. The profiles have been recorded with a nuclear track photometer with a narrow slit. The tracks studied were produced by stopping cosmic ray particles with the charges 6, 12, 18, 24, and 26. The measurements cover the residual range interval 0 < R < 1000 μm, implying ion velocities below 0.33 c. Two types of emulsion with different sensitivity, Ilford GS and Ilford K2, have been investigated. The measured track widths in K2 are quite well described theoretically, whereas regarding the measurements in G5 there is some disagreement between experimental and theoretical track widths.

Transthoracic direct current shock is the recommended treatment for ventricular fibrillation in children as in adults. To determine the appropriate energy dose, data were collected from 71 defibrillation attempts in 27 children. Sixty-three of the 71 shocks (89%) were successful in terminating fibrillation. Fifty-seven shocks were within 10 watt-seconds (w-sec) above or below an energy dose of 2 w-sec/kg of body weight. Fifty-two (91%) of these were effective and five (9%) were ineffective. In every case, fibrillation was ultimately terminated by a shock of 4 w-sec/kg or less. The results of these studies suggest that an energy dose of 2 w-sec/kg (or approximately 1 w-sec/lb) is adequate to defibrillate most children weighing under 50 kg. We currently use 2 w-sec/kg and double the energy dose if the first defibrillation attempt is unsuccessful.

As optical lithography moves into the area of submicron geometries, an increased understanding of lithographic process parameters is required. One area which requires careful examination is the interaction of the photoresist with specific spectral components of the actinic light. This will allow the photoresist performance to be separated from the performance of the imaging optics. An accurate indication of photoresist performance requires the measurement of photoresist response to a specific wavelength and energy dose. The spectrosensitometer reported on here was developed to address this need.

The effect of transthoracic direct current countershock on the myocardium of 21 newborn piglets was studied. Myocardial damage was quantified by measuring the myocardial uptake of technetium-99m pyrophosphate injected 24 hours after countershock. Substantial myocardial damage occurred in animals given greater than 150 joules/kg but not at lower energy doses. Damage occurred in both ventricular free walls, but more frequently in the right ventricle. The epicardial half of the myocardium was more severely affected than the endocardial half. The relationship between myocardial damage and total countershock energy dose was well modeled by an exponential function. Transthoracic direct current countershock appears unlikely to cause myocardial damage in newborn piglets unless greatly elevated energy doses are employed.

For repair of damage caused by irradiation of ionizing particles a cell needs enzyms, energy and time. Here, the time required for repair processes is investigated. But not the method of “liquid holding repair” normally applied to yeast and causing an artifical increasing number of surviving cells is taken into account. Here the segmentation of single cells within the first four generations after irradiation are observed and the time behaviour from budding to budding is registrated in dependence of energy dose and ionization density. These time intervalls are self controlled.

A 75 year old male patient was diagnosed of multiple “basal cell carcinoma in a surface area of l8 × 21 cm2 of the dorsal skin. Contraindications for surgery and radiation therapy made the patient eligible for phototherapy. After hematoporphyrln-derivative (HpD) administration at the dose of 3 mg/kg, body weight, the entire area of lesions was treated 2 times and in 12 fractionated areas, by using Argon or Dye lasers and different exposure times. Five of the 12 fractions were treated with Argon-ion laser at 100 mW/cm2 average irradiance for 20 min, whereas 7 fractions were treated at the same irradiance with Dye laser for 10 min in one, 15 min in 3 and 20 min for the remaining 3. Energy dose of 60 J/cm2 with Dye laser irradiation and 120 J/cm2 with Argon-ion laser irradiation resulted in similar effectiveness from clinical and histologic standpoints for the studied surface epitheliomas.

Most of the studies concerned with biostimulation are subject to large statistical uncertainties. Thus it was our aim to develop a very precise and reproducible method to measure the multiplication rates of two simultaneous growing cultures, one of them being irradiated with laser, the other one kept in the dark.

Mechanochemistry utilizes mechanical forces to activate chemical bonds. It offers environmentally benign routes for both (bio) organic and inorganic syntheses. However, direct comparison of mechanochemistry results is often very challenging. In mechanochemical synthetic protocols, ball mill setup (mechanical design and grinding vessel geometry) in addition to experimental parameters (milling frequency, duration, ball count and size) vary broadly. This fact poses a severe issue to further progress in this exciting research area because ball mill setup and experimental parameters govern how much kinetic energy is transferred to a chemical reaction. In this work, we address the challenge of comparing mechanochemical reaction results by taking the energy dose provided by ball mills as a unified metric into account. In this quest, we applied kinematic modeling to two ball mills functioning under distinct working principles to express the energy dose as a mathematical function of the experimental parameters. By examining the effect of energy dose on the extent of the mechanocatalytic depolymerization (MCD) of lignocellulosic biomass (beechwood), we found linear correlations between yield of water-soluble products (WSP) and energy dose for both ball mills. Interestingly, when a substrate layer is formed on the grinding jar wall and/or grinding medium, a weak non-linear correlation between water-soluble products yield and energy dose is identified. We demonstrate that the chemical reaction’s best utilization of kinetic energy is achieved in the linear regime, which presents improved WSP yields for given energy doses. In the broader context, the current analysis outlines the usefulness of the energy dose as a unified metric in mechanochemistry to further the understanding of reaction results obtained from different ball mills operating under varied experimental conditions.

Fil: Ávalos Llano, Karina Roxana. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina. Fil: Martin Belloso, Olga. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina. Fil: Soliva Fortuny, Robert. Universidad Nacional del Nordeste. Facultad de Ciencias Exactas y Naturales y Agrimensura; Argentina. Fresh-cut strawberries were subjected to pulsed light treatments (4, 8, 12 and 16 J·cm−2) combined with a stabilizing dip. Quality changes and antioxidant properties were evaluated for 14 days at 5 °C. The treatments delayed fungal for the studied period. Surface color of treated fresh-cut strawberries was preserved in both internal and external surfaces. Doses of 4 and 8 J·cm−2 reduced softening incidence over storage. No significant differences between the total phenolic contents of untreated and treated fresh-cut strawberries were observed during storage. Vitamin C and total anthocyanin contents of the samples treated at low energy doses were maintained, whereas those of slices treated at the highest energy dose decreased between 20 and 30%, respectively. On the other hand, initial antioxidant capacity was better kept in all samples during storage regardless the applied dose. Hence, 4 and 8 J·cm−2 were the most effective treatments for maintaining quality and antioxidant properties of fresh-cut strawberries. Industrial relevance: Fresh-cut strawberries may be sold as a highly convenient, healthy and fully edible product. However, processing and packaging conditions need to ensure the maintenance of their quality characteristics and content of bioactive compounds. This study provides scientific evidence regarding the beneficial effects of pulsed light treatments combined with a quality-stabilizing dip for extending the shelf-life of fresh-cut fruit. These combined treatments may be economically viable at industrial level because of their low energy requirements and reduced treatment time.

Previous studies have suggested that shocks of 5-10 J are required for direct ventricular defibrillation during open heart surgery. However, the efficacy of shocks of less than 5 J, the effects of thermal, biochemical, and temporal factors, and the influence of disease process on defibrillation have not been fully investigated, particularly with modern techniques of myocardial preservation. The purpose of this prospective study in 150 adult cardiac surgical patients was to evaluate the energy, current, and myocardial resistance with low energy DC shocks of 1, 2.5, and 5 J and to relate which biochemical, temporal, thermal, or other factors influence the outcome of a DC shock. Twenty-eight percent of shocks of 1 J and 55% of shocks of 2.5 J produced defibrillation. Above 2.5 J, the success rate reached a plateau at 55%. Other factors associated with the success of DC shocks were high normal serum potassium levels, high PaO2, high ionized calcium levels, and longer reperfusion times at mean arterial and coronary perfusion pressures above 50 mm Hg. Disease process may also play a role because patients with valvular heart disease were more difficult to defibrillate. Heart weight and thickness of ventricular myocardium, measured angiographically, appeared less important in direct defibrillation, except with 1 J shocks when thinner-walled ventricles defibrillated more easily.

BeO thin-film dosemeters covered with conducting polycarbonate foils of different thickness (1.9–19.2 mg/cm2) were irradiated on a phantom with a constant energy dose from 147Pm, 204Tl, and 90Sr+90Y beta sources. The dependence of their TSEE response on both the foil thickness and the mean beta energy is reported.