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[en] A functional relationship determining the survival curve for reproductive cell death caused by low -LET radiation is derived on the basis of Lea's repair/interaction model. Radiation-induced primary lesions are assumed to interact pair-wise to form long-lived lethal lesions, simultaneously with the repair of the primary lesions. The formula derived for a short single irradiation gives a typical shouldered survival curve. At doses below the shoulder the interaction entirely occurs at low levels of primary lesion concentration, resulting in the parabolic shape of the logarithmic survival curve. At higher doses the interaction initially proceeds at high levels of primary lesion concentration, a state whose duration is determined by the dose and the finite speed of the first-order reaction of repair; this initial phase of the interaction results in the exponential tail of the survival curve. Survival after fractionated and protracted irradiation are also obtained. The dependence of cell survival on the irradiation conditions can be interpreted in terms of the basic parameters of the model. (author)
[en] We prove the existence of novel, shock-fronted travelling wave solutions to a model of wound healing angiogenesis studied in Pettet et al (2000 IMA J. Math. App. Med. 17 395–413) assuming two conjectures hold. In the previous work, the authors showed that for certain parameter values, a heteroclinic orbit in the phase plane representing a smooth travelling wave solution exists. However, upon varying one of the parameters, the heteroclinic orbit was destroyed, or rather cut-off, by a wall of singularities in the phase plane. As a result, they concluded that under this parameter regime no travelling wave solutions existed. Using techniques from geometric singular perturbation theory and canard theory, we show that a travelling wave solution actually still exists for this parameter regime. We construct a heteroclinic orbit passing through the wall of singularities via a folded saddle canard point onto a repelling slow manifold. The orbit leaves this manifold via the fast dynamics and lands on the attracting slow manifold, finally connecting to its end state. This new travelling wave is no longer smooth but exhibits a sharp front or shock. Finally, we identify regions in parameter space where we expect that similar solutions exist. Moreover, we discuss the possibility of more exotic solutions. (paper)
[en] Based on the principle of emulsion technology and self-assembly of materials, aromatic isocyanate derivatives easily reacted with polyols to form polyurethanes, and nonaromatic isocyanate derivatives were responsible for generating the capsule core of the self-healing microcapsules. In this paper, epoxy resin-based self-healing smart anticorrosion coatings with different types of microcapsules were prepared. The cores were IPDI/TMP–IPDI/DiPE–IPDI. The optimal conditions for the preparation of self-repairing microcapsules to achieve controlled assembly of a microcapsule material structure were determined. We set up a test model, incorporating thermal analysis, depression repair level calculation, salt spray corrosion tests, adhesion tests, and other indicators of application performance. The corrosion resistance was in the order: DiPE–IPDI > TMP–IPDI > IPDI > pure epoxy. The experimental results showed a self-healing efficiency of more than 80% for cores of DiPE–IPDI. Taking into account the overall properties, the best-quality coatings contained approximately 5% microcapsules of DiPE–IPDI.
[en] This study was aimed at evaluating the sanitary harmlessness of radiation-treated food products. The procedure used involved biological and microbiological tests, physicochemical analyses, and organoleptic studies. (E.T.)
[en] The high radiosensitivity of the lymphoid tissues is mainly due to a high interphase death of lymphocytes. The lymphoid tissues functionally show a high radiosensitivity as has been observed for other cell renewal systems such as bone marrow, gut and skin. Repopulation of lymphoid tissues with immune responsive precursor cells occurs more slowly than repopulation of haemoporetic tissues with stem cells
[en] Centella Asiatica is one of those phyto chemical that has been consume for hundreds years and it is claimed that the plant possess various healing effect and antioxidant properties. For many years, a lot of commercial and medicinal researches have been focusing their resources on this plant. Hence, the profiling of this plant is vital. This study was done to investigate the behaviour of active components in two different accessions commercially grown in Johore Bahru. Research procedures were carried out according to the modified method utilizing TLC and HPLC analysis method. The findings suggested that in different parts of Centella Asiatica contain different amount of phytochemicals. The highest concentration of phytochemicals was found in the second accession that was asiaticoside (2.56 μg/ ml), madecasoside (5.30 μg/ ml) and asiatic acids (3421.60 μg/ ml). Leaves contain a higher concentration of those phytochemicals relative to the petioles and the roots. (author)
[en] The authors propose a model for the maximum repair factor which is independent of the saturation effect of the maximum Elkind repair, and present experimental dose-response curves for the survival rates of V-79 cells for comparison. It is pointed out that the parabolic shape of the dose-response curve makes it possible to explain the progressive weakening of the CFU of the surviving cells which goes on with increasing dose. (U.K.)
[en] Further to prior development in enhancing structural health using smart materials, an innovative class of materials characterized by the ability to feel senses like humans, i.e. ‘nervous materials’, is discussed. Designed at all scales, these materials will enhance personnel and public safety, and secure greater reliability of products. Materials may fail suddenly, but any system wishes that failure is known in good time and delayed until safe conditions are reached. Nervous materials are expected to be the solution to this statement. This new class of materials is based on the novel concept of materials capable of feeling multiple structural and external stimuli, e.g. stress, force, pressure and temperature, while feeding information back to a controller for appropriate real-time action. The strain–stress state is developed in real time with the identified and characterized source of stimulus, with optimized time response to retrieve initial specified conditions, e.g. shape and strength. Sensors are volumetrically embedded and distributed, emulating the human nervous system. Immediate applications are in aircraft, cars, nuclear energy and robotics. Such materials will reduce maintenance costs, detect initial failures and delay them with self-healing. This article reviews the common aspects and challenges surrounding this new class of materials with types of sensors to be embedded seamlessly or inherently, including appropriate embedding manufacturing techniques with modeling and simulation methods. (focus issue review)
[en] Multiple shoot development and plant regeneration were achieved from nodal segments of Phyla nodiflora. Percentage of shoot regeneration was highest (90) when the explants were cultured on MS medium supplemented with 2-3 mg/l BA. The MS medium supplemented with 2 mg/l Kin was found most effective for shoot multiplication where number of shoots per explant was found maximum (5.7). Highest shoot elongation (4.9 cm) was found when medium was supplemented with 1 mg/l GA3. Supplementation of 1 and 1.5 mg/l IBA in half strength of MS medium appeared best for early rooting (15-20 days). However, highest per cent (85) of cuttings rooted on 1 mg/l NAA. Highest number (6.8) and length (2.8 cm) of roots per microcuttings were obtained in 1.0 mg/l IBA supplemented medium. The complete plants were gradually acclimatized and eventually transferred to soil.(authors)
[en] The sensitivity of the black hole spectrum when introducing short distance dispersion is studied in the context of atomic Bose condensates. By considering flows characterized by several length scales, we show that, while the spectrum remains remarkably Planckian, the temperature is no longer fixed by the surface gravity. Rather it is determined by the average of the flow gradient across the horizon over an interval fixed by the healing length and the surface gravity, as if the horizon were broadened. This remains valid as long as the flow does not induce nonadiabatic effects that produce oscillations or some parametric amplification of the flux.