EPR of copper(II) chloride complexes with diphosphine dioxides

Stepwise formation of copper(ll) chloride complexes with diphosphine dioxides has been studied using paramagnetic resonance. It was found that in complexes with a copper:ligand composition of 11 substituents have little effect on parameters of the anisotropic EPR spectra. The spectra of complexes with a metal:ligand composition of 12 are considerably more sensitive to the introduction of substituents; this is explained by sterically dependent differences in the structure of the complexes. The possibility of trisligand complexes being formed is evidently largely determined by the size of the groups on the phosphorus atoms.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 362–368, February, 1991.     

Neutralization and Clarification of Strongly Alkaline Wastewater from Silicate Production,Based on Microflotation with Chemical Agents

A study was made of neutralization and clarification of wastewater from silicate production, which exhibits buffer properties. The promise of a two-stage procedure involving the primary thickening of the dispersed phase, followed by separation of the dispersed phase and water by flotation, was elucidated. The choice of the polymeric reagent and its concentration was substantiated.     

Formation of nanocrystalline BiFeO<Subscript>3</Subscript> under hydrothermal conditions

The formation of bismuth orthoferrite under hydrothermal conditions at temperature 160, 180, or 200°С and pressure 100 MPa in aqueous solution of potassium hydroxide has been studied. The determined composition and structure of polycrystalline phase with sillenite structure have evidenced its formation at the interface of the crystallites of amorphous iron oxide. It has been shown that the formation of polycrystalline round-shaped BiFeO₃ particles with size about 20 μm occurs via aggregation of perovskite-type phase crystallites (38–70 nm). Pycnometric density of BiFeO₃ and the amorphous phase has been determined, and Mossbauer spectra reflecting the state of iron in the phases coexisting during the formation of BiFeO₃ have been analyzed.     

Final results on μe-pair production in neutrino interactions in the SKAT freon bubble chamber experiment

We present the final results from the search for μe pairs produced in neutrino interactions using the freon filled bubble chamber SKAT. The rate of μ^? e ⁺ pairs to charged current events above the charm threshold is \(R_{\mu ^ - e^ + } = (4.8 \pm 1.1)10^{ - 3} \) . Assuming charm particle production to be the origin of the positron we calculate \(R_{\Lambda _c^ + } = (6.2 \pm 3.1)10^{ - 2} \) andR _D =(2.8±0.9)10^?2. We observe no considerable μ^? e ^? pair production above the background. In the regionE _v >3 GeV,p _μ,e >1.0 GeV/c andp _μ>p _e we find with a 90% confidence level the limit \(R_{\mu ^ - e^ - }< 1.7 10^{ - 4} \) .     

Fluorinated 1,4,2-Oxazaphospholines and their Opening by Nucleophiles

We have found that fluorinated 1,4,2-oxazaphospholines are highly electrophilic phosphorylation reagents for alcohols, thiols, amines, and dialkyl phosphites. Phosphorylation proceeds by opening of the P-O bond to yield the corresponding phosphinates.     

Enzyme-functionalized mesoporous silica for bioanalytical applications

The unique properties of mesoporous silica materials (MPs) have attracted substantial interest for use as enzyme-immobilization matrices. These features include high surface area, chemical, thermal, and mechanical stability, highly uniform pore distribution and tunable pore size, high adsorption capacity, and an ordered porous network for free diffusion of substrates and reaction products. Research demonstrated that enzymes encapsulated or entrapped in MPs retain their biocatalytic activity and are more stable than enzymes in solution. This review discusses recent advances in the study and use of mesoporous silica for enzyme immobilization and application in biosensor technology. Different types of MPs, their morphological and structural characteristics, and strategies used for their functionalization with enzymes are discussed. Finally, prospective and potential benefits of these materials for bioanalytical applications and biosensor technology are also presented. Figure Enzyme-functionalized mesoporous silica fibers and their integration in a biosensor design. The immobilization process takes place essentially in the silica micropores.     

X-ray diffractometry and electron microscopy of porous silicon layers at different stages of oxidation in air

Porous silicon layers prepared by anodic etching under different conditions have been systematically studied in the course of their natural oxidation (aging) in air by many-crystal X-ray diffractometry and transmission electron microscopy. Quantitative information on the strains and crystal structure of layers has been obtained using a combination of measurements of the 004 symmetric and 224 asymmetric reflections in the Bragg geometry on double-crystal and triple-crystal X-ray diffractometers. It has been revealed that the aging of porous silicon is accompanied by an increase in macrostrains and microstrains, as well as in micro-misorientations of crystal fragments, which lead to gradual destruction of porous layers up to their complete amorphization.     

Selective targeting of antibody conjugated multifunctional nanoclusters (nanoroses) to epidermal growth factor receptors in cancer cells

The ability of smaller than 100 nm antibody (Ab) nanoparticle conjugates to target and modulate the biology of specific cell types may enable major advancements in cellular imaging and therapy in cancer. A key challenge is to load a high degree of targeting, imaging, and therapeutic functionality into small, yet stable particles. A versatile method called thin autocatalytic growth on substrate (TAGs) has been developed in our previous study to form ultrathin and asymmetric gold coatings on iron oxide nanocluster cores producing exceptional near-infrared (NIR) absorbance. AlexaFluor 488 labeled Abs were used to correlate the number of Abs conjugated to iron oxide/gold nanoclusters (nanoroses) with the hydrodynamic size. A transition from submonolayer to multilayer aggregates of Abs on the nanorose surface was observed for 54 Abs and an overall particle diameter of ～60-65 nm. The hydrodynamic diameter indicated coverage of a monolayer of 54 Abs, in agreement with the prediction of a geometric model, by assuming a circular footprint of 16.9 nm diameter per Ab molecule. The targeting efficacy of nanoclusters conjugated with monoclonal Abs specific for epidermal growth factor receptor (EGFR) was evaluated in A431 cancer cells using dark field microscopy and atomic absorbance spectrometry (AAS) analysis. Intense NIR scattering was achieved from both high uptake of nanoclusters in cells and high intrinsic NIR absorbance of individual nanoclusters. Dual mode imaging with dark field reflectance microscopy and fluorescence microscopy indicates the Abs remained attached to the Au surfaces upon the uptake by the cancer cells. The ability to load intense multifunctionality, specifically strong NIR absorbance, conjugation of an Ab monolayer in addition to a strong r2 MRI contrast that was previously demonstrated in a total particle size of only 63 nm, is an important step forward in development of theranostic agents for combined molecular specific imaging and therapy.