Optical pumping of the electronic and nuclear spin of single charge-tunable quantum dots

We present a comprehensive examination of optical pumping of spins in individual GaAs quantum dots as we change the net charge from positive to neutral to negative with a charge-tunable heterostructure. Negative photoluminescence polarization memory is enhanced by optical pumping of ground state electron spins, which we prove with the first measurements of the Hanle effect on an individual quantum dot. We use the Overhauser effect in a high longitudinal magnetic field to demonstrate efficient optical pumping of nuclear spins for all three charge states of the quantum dot.     

Cyclophosphorylation of polyphenols by diamidoarylphosphites

It was found that the cyclophosphorylation of polyphenols by diamidoarylphosphites proceeds via the rupture of only one P-N bond and one P-O bond, the second P-N bond remaining intact. It is supposed that the unusual lack of reactivity of the P-N bond is due to the spatial arrangement of the amido group with respect to the reaction site in phosphorylated intermediates 5.     

Twistor connection and the Palatini method

For the Yang-Mills Lagrangian of the twistor connection, an analog of the Palatini variational method is considered in which the variations of the twistor connection A_m and metric g_ab, are taken to be independent. It is shown that varying the Lagrangian with respect to the connection establishes a relation between A_m and g_ab (i.e., defines a standard twistor connection, postulated earlier), while varying with respect to the metric with a subsequent substitution of explicit expressions of the standard twistor connection leads to the Bach vacuum equations, describing the dynamics of conformal gravity.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 94–97, May, 1988.The author thanks Professor N. V. Mitskevich for his attention to this work and useful discussions.     

The twistor connection and gauge invariance principle

It is shown that the twistor connection of the local twistor theory can be regarded as a gauge field whose Yang-Mills equations are equivalent to Bach equations of gravity.     

Approaches to the Synthesis of Conjugates of Phosphocavitands and Natural Compounds

Possibilities for the design of phosphocavitand conjugates with natural alcohols and phenols were studied. First cavitand conjugates bearing biomolecular fragments at the periphery of the molecular cup were obtained by alcoholysis of tetrachlorophosphitocavitands and cyclophosphorylation of calix[4]resorcinarenes.     

C-Phosphorylation of Compounds with the Electron-Rich Double Carbon-Nitrogen Bond

Abstract

C-phosphorylation of N,N-dimethylhydrazones and N,N-dimethyl-N′-arylamidines by phosphorus tribromide was first accomplished. It directs to the formation of novel types of functional P(III) derivatives (1–3)     

Synthesis and characterization of bismuth-containing oxyfluoroniobate glasses

New glasses are prepared in the MnNbOF₅-BaF₂-BiF₃ system. The thermal parameters of these glasses are analyzed as influenced by bismuth trifluoride. IR and Raman spectroscopy shows that the glass structures are built of Nb(O, F)₆ polyhedra, which are linked by oxygen bridges to form glass nets via. A medium-order order region in the glass includes fluoroniobate polyhedra not linked directly to bismuth trifluoride polyhedra. A Ba_0.55Bi_0.45F_2.45 crystalline phase is discovered at 320°C in a glass of composition 20MnNbOF₅-40BaF₂-40BiF₃.     

Temozolomide Efficacy and Metabolism: The Implicit Relevance of Nanoscale Delivery Systems

The most common primary malignant brain tumors in adults are gliomas. Glioblastoma is the most prevalent and aggressive tumor subtype of glioma. Current standards for the treatment of glioblastoma include a combination of surgical, radiation, and drug therapy methods. The drug therapy currently includes temozolomide (TMZ), an alkylating agent, and bevacizumab, a recombinant monoclonal IgG1 antibody that selectively binds to and inhibits the biological activity of vascular endothelial growth factor. Supplementation of glioblastoma radiation therapy with TMZ increased patient survival from 12.1 to 14.6 months. The specificity of TMZ effect on brain tumors is largely determined by special aspects of its pharmacokinetics. TMZ is an orally bioavailable prodrug, which is well absorbed from the gastrointestinal tract and is converted to its active alkylating metabolite 5-(3-methyl triazen-1-yl)imidazole-4-carbozamide (MTIC) spontaneously in physiological condition that does not require hepatic involvement. MTIC produced in the plasma is not able to cross the BBB and is formed locally in the brain. A promising way to increase the effectiveness of TMZ chemotherapy for glioblastoma is to prevent its hydrolysis in peripheral tissues and thereby increase the drug concentration in the brain that nanoscale delivery systems can provide. The review discusses possible ways to increase the efficacy of TMZ using nanocarriers.