Temple University

About: Temple University is a education organization based out in Philadelphia, Pennsylvania, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 32154 authors who have published 64375 publications receiving 2219828 citations.

Inorganic–Organic Nanotube Composites from Template Mineralization of Tobacco Mosaic Virus

Abstract: The use of biological molecules, assemblies and systems in the development of inorganic materials synthesis continues to offer new and exciting alternatives to conventional synthetic strategies. Biological templates, such as protein cages, viroid capsules, bacterial rhapidosomes, S-layers, multicellular superstructures, biolipid cylinders, and DNA, have been utilized to direct the deposition, assembly, and patterning of inorganic nanoparticles and microstructures. In this paper, we report a new approach to the template-directed synthesis of inorganic±organic nanotubes using tobacco mosaic virus (TMV). TMV is a remarkably stable virion, remaining intact at temperatures up to 60 C and at pH values between 2 and 10. Each viral particle consists of 2130 identical protein subunits arranged in a helical motif around a single strand of RNA to produce a hollow protein tube, 300 18 nm in size, with a 4 nm-wide central channel. The internal and external surfaces of the protein consist of repeated patterns of charged amino acid residues, such as glutamate, aspartate, arginine, and lysine. In principle, these functionalities should offer a wide variety of nucleation sites for surface-controlled inorganic deposition, which, in association with the high thermal and pH stability, could be exploited in the synthesis of unusual materials such as high-aspect-ratio composites and protein-confined inorganic nanowires. Here we show that TMV is a suitable template for reactions such as co-crystallization (CdS and PbS), oxidative hydrolysis (iron oxides), and sol-gel condensation (SiO2) (Fig. 1).

The Courage to Create

Abstract: What if imagination and art are not, as many of us might think, the frosting on life but the fountainhead of human experience? What if our logic and science derive from art forms, rather than the other way around? In this trenchant volume, Rollo May helps all of us find those creative impulses that, once liberated, offer new possibilities for achievement. A renowned therapist and inspiring guide, Dr. May draws on his experience to show how we can break out of old patterns in our lives. His insightful book offers us a way through our fears into a fully realized self.

Creativity and knowledge: A challenge to theories.

Abstract: An important component of research in creativity has been the development of theories concerning the mechanisms underlying creative thinking. Modern theories of creative thinking have been advanced from many different viewpoints, ranging from Guilford's pioneering psychometric theory (e.g., 1950; see also Runco, 1991) to those developing out of clinical interests, broadly conceived (e.g., Eysenck, 1993). Other theories have developed out of Gestalt psychology (e.g., Wertheimer, 1982), traditional associationistic experimental psychology (e.g., Mednick, 1962), Darwinian theory (e.g., Campbell, 1960; Simonton, 1988, 1995); social-psychological perspectives (e.g., Amabile, 1983), investment perspectives (e.g., Sternberg & Lubart, 1995), and modern cognitive science (e.g., Martindale, 1995). In this chapter, I examine one critical issue confronting all such theories: the role of knowledge in creativity. Although the various theoretical views proposed by psychologists appear on the surface to be very different, there is among many of them, including all those just cited, one critical assumption concerning the relationship between knowledge and creativity. Since creative thinking by definition goes beyond knowledge, there is implicitly or explicitly assumed to be a tension between knowledge and creativity. Knowledge may provide the basic elements, the building blocks out of which are constructed new ideas, but in order for these building blocks to be available, the mortar holding the old ideas together must not be too strong.

Evidence From Sertoli Cell-Depleted Rats Indicates That Spermatid Number in Adults Depends on Numbers of Sertoli Cells Produced During Perinatal Development*

Abstract: To probe the relationship between the size of the Sertoli cell population, established during perinatal development, and production of germ cells in the adult testis, a Sertoli cell-depleted rat model was developed. This was accomplished by delivering an antimitotic drug, cytosine arabinoside (araC), directly to the testis of newborn pups. Initial studies of these araC-treated neonates indicated that 1) the drug is cleared rapidly from the testis; 2) it substantially reduces the level of Sertoli cell proliferation; 3) Sertoli cell division ceases at a normal time in spite of the previous drug treatment; and 4) araC itself has no residual effect on germ cell proliferation, which begins several days after the injection. Pups given araC were allowed to reach maturity, and their testes were perfuse-fixed for light microscopic morphometry. When the numbers of Sertoli cells in adult rats given araC as were compared with those in normal littermates, a 54% decrease in the size of the Sertoli cell population was detected in treated rats, now referred to as Sertoli cell-depleted. Moreover, when round spermatids were quantified and compared in normal and Sertoli cell-depleted adults, testes of the latter were found to contain 55% fewer round spermatids. Since, in the araC-treated group, the decrease in Sertoli cell population size was paralleled by a reduction in spermatid production of equal magnitude, the number of round spermatids per Sertoli cell was essentially identical in normal and Sertoli cell-depleted animals. Measurements of serum androgen-binding protein (ABP) and FSH in both groups indicated that the circulating level of ABP in Sertoli cell-depleted rats was approximately half, and the concentration of FSH approximately twice, that in normal animals. Thus, even though FSH is elevated in Sertoli cell-depleted rats, the production of ABP per Sertoli cell is unchanged. In addition, collective volume of Leydig cells and ventral prostate weights were normal in the Sertoli cell-depleted group, suggesting that Leydig cell function in these rats is normal. In summary, a Sertoli cell-depleted rat model has been produced by interfering specifically with Sertoli cell proliferation early in postnatal life, before onset of germ cell division. Moreover, our findings with this model indicate that production of normal numbers of germ cells in adults depends, at least in part, on the size of the Sertoli cell population. Thus, our observations identify the perinatal period, when the Sertoli cell population is established, as critical for development of quantitatively normal spermatogenesis in the adult.