DNA and RNA are the only known natural genetic materials. Systematic modification of each of their chemical building blocks (nucleobase, sugar, and phosphate) has enabled the study of the key properties that make those nucleic acids genetic materials. All three moieties contribute to replication and, significantly, all three moieties can be replaced by synthetic analogs without loss of function. Synthetic nucleic acid polymers capable of storing and propagating information not only expand the central dogma, but also highlight that DNA (...) and RNA are not unique chemical solutions for genetic information storage. By considering replication as a question of information transfer, we propose that any polymer that can be replicated could serve as a genetic material.Editor's suggested further reading in BioEssays Xenobiology: A new form of life as the ultimate biosafety tool Abstract. (shrink)

Hydroxycamptothecin is a potent antineoplastic agent that has shown efficacy against multiple tumor lines in vitro. eww140918dxn This is the first study to investigate the release, distribution, and efficacy of hydroxycamptothecin which was incorporated into the biodegradable polymer Polylactic Acid (PLA), and implant into brain directly. In vitro release curve generated showed that a large initial release occurred over the first three days and was followed by a steady, but considerably slower rate of release over the next 25 days. After (...) implanting the discs into 40 male SD rats, the animals were followed up to 28 days, where the concentration in brain tissue was far higher than that in peripheral blood at the each of the eight time-points evaluated, and it was also within the therapeutic range for C6 cells tested in vitro. The in vivoefficacy of the discs was evaluated with rats inoculated intracranially with C6 glioma and treated with hydroxycamptothecin polymer compared to intravenous as well as intratumoral injections; the median survival is 21.1, 13.9, 14.9 days, respectively. Given these data, we conclude that the biodegradable polymer PLA releases hydroxycamptothecin, producing tumoricidal levels in brain tissues and prolonging survival in a rat glioma model. (shrink)

We give an elementary introduction to non-standard analysis and its applications to the theory of stochastic processes. This is based on a joint book with J. E. Fenstad, R. Høegh-Krohn and T. Lindstrøm. In particular we give a discussion of an hyperfinite theory of Dirichlet forms with applications to the study of the Hamiltonian for a quantum mechanical particle in the potential created by a polymer. We also discuss new results on the existence of attractive polymer measures in dimension d (...) ≤ 5, with applications to the (φ 1 2 φ 2 2 )d-mode1 of interacting quantum fields. (shrink)

Until recently philosophy of physics has been overshadowed by the idea that the important philosophical issues that can be derived from physics are related only to fundamental theories, such as quantum mechanics and relativity. Applied fields of physics were deemed as unimportant. The argument for such a position lays in thinking that these applied fields of physics depend in their theoretical representations on fundamental theories and hence are reducible to these fundamental theories. It would be hard to defend such a (...) position, keeping in mind that applied fields of physics have a life of its own totally separate from fundamental physics and have in fact a lot to say to philosophers. The field of polymers is one of the branches of applied physics that has a lot to say to philosophers. It is a field of physics where theoreticians failed to present a coherent theory that can capture the different ways polymers can be built. This paper examines the difficulties that keep theoreticians away from having such a theory, revealing what kind of philosophical lessons polymers might have. The main thesis is: even in the cases where a theory predict the possibility of developing a specific type of polymers that was not previously known, the exact model that represent the outcome polymer theoretically will not be even in principle derivable from the theory that predicted its existence in the first place. (shrink)

The theoretical principles and methodological aspects of the thermal field-flow fractionation applied to study the thermal diffusion of the macromolecules in solution and colloidal particles in suspension were developed. The theoretical analysis indicated that the miniaturization of the separation channel for thermal field-flow fractionation should improve the performance of this technique. A new microchannel was conceived and built. The experimental results obtained for polymer samples with an extended range of molar masses from relatively low up to ultrahigh and for the (...) colloidal particles confirmed that the achieved resolution is the same but the versatility of the microchannel is superior to that of the standard size channels owing to the substantial decrease in the heat energy flux. This important improvement allows us to achieve very high resolution when applying constant-field-force operation, it makes it much easier to program the temperature drop which is an advantageous operational mode from the viewpoint of the time of analysis, and it extends considerably the range of perfectly controlled temperatures of the cold and hot walls. The sample amount needed for one analysis can be as small as a few nanograms. (shrink)

Musks, the foundation of many perfumes, as well as other ingredients of perfumes, were critical objects of study for establishing theoretical concepts about large ring chemical compounds and polymerization in the 1920s and 1930s. Because fragrance chemistry has been underdeveloped in the historiography, doubtless partly because it has become associated with the feminine, this has been ignored in the historiography. This essay highlights the strategic importance of perfume research, looking in particular at the work of Leopold Ružičkač, 1939 Nobel laureate (...) in chemistry who had close ties to the fragrance industry, and Wallace Carothers at DuPont, whose well-known work on polymerization was intimately concerned with large ring compounds, including musk, and which indeed led to DuPont producing a synthetic musk in the 1930s. (shrink)