Novel mixed amido/imido/guanidinato complexes of niobium are reported. The complexes were synthesized by insertion of two equivalents of di-isopropylcarbodiimide (i-Pr-cdi) or bis-cyclohexylcarbodiimide (Cy-cdi) respectively, into the niobium-amido bonds of [Nb(NR(2))(3)(N-t-Bu)] (, R = Me; , R = Et) starting out from [NbCl(3)(N-t-Bu)(py)(2)] and the respective LiNR(2) reagent (py = pyridine). ...

Clay from deposit Bilalovac, Central Bosnia, was characterized by chemical, IR, XRD and DTA/TG analysis. The major mineral components are kaolinite, illite, muscovite and quartz. Raw clay may be used for pottery products and terracotta. Clay was beneficiated by wet method removing fraction over 20 μm. Beneficiation process increased content of kaolinite and decreased content of quartz. Benefici...

The niobium complex [NbCpCl4] (Cp @g-C5H4(SiCl2Me)) (1) with a functionalized (dichloromethylsilyl)cyclopentadienyl ligand was isolated by the reaction of [NbCl5] with C5H4(SiCl2Me)(SiMe3). Complex 1 was a precursor for the imido silylamido derivative [NbCpCl2(NtBu)] (Cp @g-C5H4[SiClMe(NHtBu)]) (2) after addition of LiNHtBu, which subsequently gave the dichlorosilyl compound [NbCpCl2(NtBu)] (3)...

The pathway for de novo biosynthesis of purine nucleotides contains two one-carbon transfer reactions catalyzed by glycinamide ribotide (GAR) and 5-aminoimidazole-4-carboxamide ribotide (AICAR) transformylases in which N10-formyltetrahydrofolate is the one-carbon donor. We have found that the antifolates methotrexate (MTX) and piritrexim (PTX) completely block the de novo purine pathway in mous...

High resolution (<10 nm) transmission electron microscopy (TEM), energy-®ltering TEM (EFTEM), and electron energy loss spectroscopy (EELS) have been used for the direct microstructural imaging and analysis of clay-organic matter aggregates in ®ne-grained aquatic sediments from Jourdan River Estuary, MS, USA. EFTEM and EELS allow rapid, high-resolution spatial mapping and analysis of light eleme...

Some organisms disperse energy, associated with the transportation of resource, which is not necessarily food. Stingless bees of Central Amazonia (Melipona flavolineata and M. lateralis) collect clay in banks along streams for nest building. The moisture of the clay varies along the bank, and bees collect clay from specific location, indicating that there is some sort of preference regarding th...

Define a mixture with volume V containing a certain amount of clay (Vc) and sand (Vs), i.e. V = Vc + Vs. The intrinsic porosity of the clay is φc, defined as the ratio of pore volume in the clay V c p to the volume of clay, i.e. φc = V c p /Vc, and the intrinsic porosity of sand is φs = V s p /Vs. The surface areas of the pores in the clay and in the sand are noted S p and S s p respectively. S...

Metal ions present on smectite clay (montmorillonite) platelets have preferential reactivity towards peroxy/alkoxy groups during polyamide 6 (PA6) thermal decomposition. This changes the decomposition pathway and negatively affects the ignition response of PA6. To restrict these interfacial interactions, high-temperature-resistant polymers such as polyetherimide (PEI) and polyimide (PI) were us...

A high-yielding and diastereoselective route to biologically significant 2-aryl- and 2-alkyl-3-amido dihydroquinolones has been developed in up to 90 : 10 e.r. by employing a novel Lewis acidic BINOL-derived copper(ii) catalyst.