The molecular formula of a new antimetabolite produced by Streptomyces purpurascens was determined to be C5H5N5O2 by elemental analysis, FD-MS and 13C NMR. Reduction of this antimetabolite with Raney nickel yielded guanine. The antimetabolite was distinguishable from known N-hydroxyguanines by comparison of their UV spectra. The structure of the antimetabolite was finally established to be 7-hy...

In the course of screening for new antitumor substances, BE-18591 (la) was isolated from cultures of Streptomyces sp. BA18591X). The isolation and physico-chemical properties together with biological activities are reported in the preceding paper. In this paper, the structure elucidation is described. The physico-chemical properties of la were summarized in a previous paper1*. The molecular for...

Life is that which evolves. Living systems are the products of evolutionary processes and can undergo further evolution. A crucial question for the origin of life is the following: when do chemical kinetics become evolutionary dynamics? In this Account, we review properties of "prelife" and discuss the transition from prelife to life. We describe prelife as a chemical system where activated mon...

this paper highlights the effect of silt content on cone tip resistance in loose silty sand. in this study, twenty-seven cone penetration tests are performed in saturated silty sand samples with several different silt contents ranging from 10 to 50 percent. the samples are consolidated at three overburden stresses including 100, 200 and 300 kpa. it is shown that, as the silt content increases, ...

Pedo-spectroscopy has the potential to provide valuable information about soil physical, chemical, and biological properties. Nowadays, we may predict properties using VNIR field imaging spectra (IS) such as Prisma satellite data or laboratory (LS). The primary goal of this study is investigate machine learning models namely Partial Least Squares Regression (PLSR) Support Vector (SVR) for predi...

Francisella tularensis (FT) is gram negative, non-motile, capsulated and intracellular zoonotic fastidious bacteria, causing tularemia in both animals and human. Soil texture and heavy metals play an important role in survival and persistence of microbes in environment. In the present study, association of physical and chemical composition of soil was determined in 74 FT positive and negative s...

Management of soils to reduce the amount of PM10 emitted during agricultural tillage operations is important for attainment of air quality standards in California's San Joaquin Valley (SJV). The purpose of this study was to improve and expand upon earlier work of predicting tillage-generated dust emissions based on soil properties. We focus on gravimetric soil water content (GWC) and soil textu...

purpose: to evaluate the effect of fullerene on chemical properties of naphazoline drug in   water by density functional theory (dft) methods.   materials and methods: naphazoline belongs to the imidazoline class of sympathomimetics.   the present study on naphazoline drug and its fullerene connected form were carried out using   computerized calculations of gaussian program in b3lyp/6-31g leve...