Density functional theory computations were carried out for 11-vertex nido-p-block-hetero(carba)boranes and -borates containing silicon, germanium, tin, arsenic, antimony, sulfur, selenium and tellurium heteroatoms. A set of quantitative values called "estimated energy penalties" was derived by comparing the energies of two reference structures that differ with respect to one structural feature...

The RNA World is generally thought to have been an important link between purely prebiotic (>3.7 Ga) chemistry and modern DNA/protein biochemistry. One concern about the RNAWorld hypothesis is the geochemical stability of ribose, the sugar moiety of RNA. Prebiotic stabilization of ribose by solutions associated with borate minerals, notably colemanite, ulexite, and kernite, has been proposed as...

The vacuum-ultraviolet (VUV) spectroscopic properties of undoped and Tb(3+)-doped borates Ba(3)Ln(BO(3))(3) (Ln = Lu and Gd) with different crystal structures were investigated by using synchrotron radiation. Ba(3)Lu(BO(3))(3) (BLB) crystallizes in a hexagonal structure, whereas Ba(3)Gd(BO(3))(3) (BGB) crystallizes in a trigonal structure. The maximum host absorption for BLB and BGB was found t...

Microbial cells interact with the environment by adapting to external changes. Signal transduction pathways participate in both sensing and responding in the form of modification of gene expression patterns, enabling cell survival. The filamentous fungal-specific SltA pathway regulates tolerance to alkalinity, elevated cation concentrations and, as shown in this work, also stress conditions ind...

Boron is a widely occurring element in minerals found in the earth’s crust. It is the 51 most common element found in the earth’s crust and is found at an average concentration of 8 mg/kg (approximately 0.0008%). It is found in the environment primarily combined with oxygen in compounds called borates. Common borate compounds include boric acid, salts of boric acid (e.g., sodium tetraborates, w...

8 0 is an interesting material, showing two po2 3 lymorphs in which the boron atoms have different coordination numbers (see Figs. 1 and 2). Neither form of crystalline trioxide occurs naturally. Furthermore, it is not easy even under special conditions to prepare crystals and asure their properties. In such cases computer simulations can play an important role in determining t e structural and...

The purpose of this study was to investigate the potential for reproductive effects of inorganic borate compounds on male employees. The standardized birth ratio (SBR) methodology was used to assess fertility among male employees, using live births as the measured end point. The ratio of female to male births was also assessed. Data were collected via questionnaires and telephone follow-up inte...

Inorganic borates are encountered in many settings worldwide, spurring international efforts to develop exposure guidance (US EPA, 2004; WHO, 2009; ATSDR, 2010) and occupational exposure limits (OEL) (ACGIH, 2005; MAK, 2011). We derived an updated OEL to reflect new data and current international risk assessment frameworks. We assessed toxicity and epidemiology data on inorganic borates to iden...

Magnesium plays a special role in biochemistry because of its ability to coordinate six oxygen atoms efficiently in its first coordination shell. Such oxygen atoms may be part of one or two charged oxyanions, which means that Mg²⁺ can, for instance, tie together two different phosphate groups that are located at distance from each other in a macromolecule, and in this way be responsible for the...