The low-frequency vibrational and low-temperature thermal properties of amorphous solids are markedly different from those of crystalline solids. This situation is counterintuitive because all solid ...materials are expected to behave as a homogeneous elastic body in the continuum limit, in which vibrational modes are phonons that follow the Debye law. A number of phenomenological explanations for this situation have been proposed, which assume elastic heterogeneities, soft localized vibrations, and so on. Microscopic mean-field theories have recently been developed to predict the universal non-Debye scaling law. Considering these theoretical arguments, it is absolutely necessary to directly observe the nature of the low-frequency vibrations of amorphous solids and determine the laws that such vibrations obey. Herein, we perform an extremely large-scale vibrational mode analysis of a model amorphous solid. We find that the scaling law predicted by the mean-field theory is violated at low frequency, and in the continuum limit, the vibrational modes converge to a mixture of phonon modes that follow the Debye law and soft localized modes that follow another universal non-Debye scaling law.
We numerically study the relaxation dynamics and associated criticality of non-Brownian frictionless soft spheres below jamming in spatial dimensions
d
=
2
, 3, 4, and 8, and in the mean-field ...Mari–Kurchan model. We discover non-trivial finite-size and volume fraction dependences of the relaxation time associated to the relaxation of unjammed packings. In particular, the relaxation time is shown to diverge logarithmically with system size at any density below jamming, and no critical exponent can characterise its behaviour approaching jamming. In mean-field, the relaxation time is instead well-defined: it diverges at jamming with a critical exponent that we determine numerically and differs from an earlier mean-field prediction. We rationalise the finite
d
logarithmic divergence using an extreme-value statistics argument in which the relaxation time is dominated by the most connected region of the system. The same argument shows that the earlier proposition that relaxation dynamics and shear viscosity are directly related breaks down in large systems. The shear viscosity of non-Brownian packings is well-defined in all
d
in the thermodynamic limit, but large finite-size effects plague its measurement close to jamming.
We use computer simulations to study the thermodynamic properties of a glass-former in which a fraction c of the particles has been permanently frozen. By thermodynamic integration, we determine the ...Kauzmann, or ideal glass transition, temperature Formula at which the configurational entropy vanishes. This is done without resorting to any kind of extrapolation, i.e., Formula is indeed an equilibrium property of the system. We also measure the distribution function of the overlap, i.e., the order parameter that signals the glass state. We find that the transition line obtained from the overlap coincides with that obtained from the thermodynamic integration, thus showing that the two approaches give the same transition line. Finally, we determine the geometrical properties of the potential energy landscape, notably the T - and c dependence of the saddle index, and use these properties to obtain the dynamic transition temperature Formula. The two temperatures Formula and Formula cross at a finite value of c and indicate the point at which the glass transition line ends. These findings are qualitatively consistent with the scenario proposed by the random first-order transition theory.
Significance Confirming by experiments or simulations whether or not an ideal glass transition really exists is a daunting task, because at this point the equilibration time becomes astronomically large. Recently it has been proposed that this difficulty can be bypassed by pinning a fraction of the particles in the glass-forming system. Here we study numerically a liquid with such random pinned particles and identify the ideal glass transition point Formula at which the configurational entropy vanishes, thus realizing for the first time, to our knowledge, a glass with zero entropy. We find that as the fraction of pinned particles increases, the Formula line crosses the dynamical transition line, implying the existence of an end point at which theory predicts a new type of criticality.
Current states and future views in photodynamic therapy Yano, Shigenobu; Hirohara, Shiho; Obata, Makoto ...
Journal of photochemistry and photobiology. C, Photochemistry reviews,
03/2011, Letnik:
12, Številka:
1
Journal Article
Recenzirano
► Photodynamic therapy (PDT) is a promising a less invasive method for treating cancer. ► Porphyrin and its analogues are the most useful photosensitizers for PDT. ► The non-porphyrin ...photosensitizers have advantages over porphyrinoid ones. ► 5-Aminolevulinic acid has been much interest in PDT as a non-phototoxic prodrug. ► Fullerenes are suitable for application in PDT as an efficient photosensitizer. ► PDD has great potential for the diagnosis of small and early-stage dysplasia and cancer.
One of the long-standing goals of both researchers and oncologists is to establish a framework for the complete cure of cancer with less toxic adverse effect and improved quality of life (QOL) for patients. PDT (photodynamic therapy) has much attracted as less invasive method for treating cancer. The therapeutic properties of light have been known for thousands of years, but it was only in the last century that PDT was developed. The field on PDT is now so large. Here, we will focus on a few basic aspects such as porphyrinoid photosensitizers, non-porphyrinoid photosensitizers, 5-aminolevulinic acid and its derivatives, fullerenes as efficient photosensitizers, and, PDT and photodynamic diagnosis (PDD) for digestive cancer from the point of view of a clinical doctor, and, finally, future trends.
Water‐soluble fullerenes prepared by using solubilizing agents based on natural products are promising photosensitizers for photodynamic therapy. Cyclodextrin, β‐1,3‐glucan, lysozyme, and liposomes ...can stably solubilize not only C60 and C70, but also some C60 derivatives in water. To improve the solubilities of fullerenes, specific methods have been developed for each solubilizing agent. Water‐soluble C60 and C70 exhibit photoinduced cytotoxicity under near‐ultraviolet irradiation, but not at wavelengths over 600 nm, which are the appropriate wavelengths for photodynamic therapy. However, dyad complexes of solubilized C60 derivatives combined with light‐harvesting antenna molecules improve the photoinduced cytotoxicities at wavelengths over 600 nm. Furthermore, controlling the fullerene and antenna molecule positions within the solubilizing agents affects the performance of the photosensitizer.
On the right wavelength: Water‐soluble fullerenes prepared by using natural‐product‐based solubilizing agents have photoinduced cytotoxicities. In particular, C60 derivatives and the combination of light‐harvesting liposomal photosensitizers with fullerenes result in extremely high photoinduced cytotoxicities upon exposure to light of λ>600 nm; thus making them suitable for photodynamic therapy (see figure).
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