Functionalization of Biphenylcarbazole (CBP) with Siloxane-Hybrid Chains for Solvent-Free Liquid Materials

We report herein the synthesis of siloxane-functionalized CBP molecules (4,4′-bis(carbazole)-1,1′-biphenyl) for liquid optoelectronic applications. The room-temperature liquid state is obtained through a convenient functionalization of the molecules with heptamethyltrisiloxane chains via hydrosilylation of alkenyl spacers. The synthesis comprises screening of metal-catalyzed methodologies to introduce alkenyl linkers into carbazoles (Stille and Suzuki Miyaura cross-couplings), incorporate the alkenylcarbazoles to dihalobiphenyls (Ullmann coupling), and finally introduce the siloxane chains. The used conditions allowed the synthesis of the target compounds, despite the high reactivity of the alkenyl moieties bound to π-conjugated systems toward undesired side reactions such as polymerization, isomerization, and hydrogenation. The features of these solvent-free liquid CBP derivatives make them potentially interesting for fluidic optoelectronic applications.     

Synthesis and Stereochemistry of Some New 1,3-Oxathiane Derivatives

The synthesis and stereochemistry of some new 2,5-substituted 1,3-oxathiane derivatives are reported. The anancomeric or flexible structure of the derivatives and some peculiar cases of prochirality are revealed by NMR investigations.     

Synthesis and Stereochemistry of Some New 1,3-Dioxane Derivatives of 1,4-Diacetylbenzene

Summary.  The synthesis and stereochemistry of new 1,3-dioxane derivatives of 1,4-diacetylbenzene are reported. The anancomeric structure of these compounds, the axial orientation of the aryl group for both 1,3-dioxane rings, and the cis and trans isomerism of some of these compounds is discussed considering data of conformational analysis, NMR investigations, and single crystal X-ray diffractometry. Received September 12, 2001. Accepted (revised) November 5, 2001     

Synthesis of 2-cyanoacrylatesvia 2-cyanoacryloyl chloride

Monomers that are difficult to obtain, such as tert-butyl 2-cyanoacrylate, trimethylsilyl-methyl 2-cyanoacrylate, 2,2,3,3-tetrafluoropropyl 2-cyanoacrylate, and the previously unknown adamantyl 2-cyanoacrylate were prepared starting from 2-cyanoacryloyl chloride.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1339–1340, July, 1994.     

Activation and transfer of oxygen XV evidence for the transient opening of the pyrazine ring in n1- and n5- alkylflavin models. 4a- to 1010- adduct isomerization and pyrazine- and pyrimidine- ring contractions.

The pyrazine ring opening is proven by rearrangements leading to benzimidazoles $\text{4}$, $\text{13}$ and $\text{14}$. A 4^a- to 10^a-adduct isomerization ($\text{6}$ → $\text{7}$) and the intermediacy of a carbonyl oxide $\text{15}$ are indicated by pyrimidine ring contractions into $\text{8}$ and $\text{9}$, respectively.     

Selective separations via recrystallization

The principles of selective separations by recrystallization are explained and formulae for the calculation of decontamination factors are presented. Experiments with strontium sulfate and radioactive strontium ions demonstrate the validity of the theoretical considerations. Similar or higher decontamination factors are found than those calculated for a uniform distribution of the radioactive strontium ions between crystals and solution. The high values are explained by assuming a recrystallization mechanism which consists of dissolution and redeposition of crystal layers. The half-times of recrystallization increase sharply with Sr²⁺ or SO ₄ ²⁻ concentration in the solution. In nitric acid solutions as well as in mixtures containing nitrates and nitric acid the solubility of strontium sulfate is rather high, accordingly the decontamination factors are low under these conditions and furthermore the recrystallization half-times are long.     

Sequential associative information storage and reconstruction in a holographic circuit

After a brief discussion of the analogy between neutral and holographic information processing, a holographic circuit for associative information storage and reconstruction is described. This special system models the ability of the brain to reconstruct a sequence of previously stored informations A, B, C,…, when only one input stimulus is presented to the neural system. Furthermore the holographic system is capable of retrieving branching information, modelling the property of the brain to memorize various sequences of information with one special input.     

Conditional Response to Stress in Yeast

Summary. All living cells respond to sudden, adverse changes in their environment by evoking a stress response. Here we focus mainly on the response of the model eukaryotic organism Saccharomyces cerevisiae (bakers yeast) to an increase in external osmolarity. We summarize data demonstrating that stress responses largely depend on the existing environmental growth conditions. Nutrients and other medium parameters such as external pH determine how yeast cells sense osmotic stress circumstances and subsequently elicit adaptive responses. It is likely that the composition of cell wall and plasma membrane plays an important role in this process.Received September 3, 2002; accepted September 13, 2002 Published online May 26, 2003     

The program of Friend cell erythroid differentiation: early changes in Na+/K+ ATPase function.

Treatment of Friend erythroleukemia cells with several different chemical agents causes an early decrease in the 86Rb+ influx mediated by Na+/K+ adenosine triphosphatase (ATPase). These agents, which induce Friend cells to differentiate, include dimethylsulfoxide (DMSO), ouabain, hypoxanthine, and actinomycin D. The magnitude of the early decrease in 86Rb+ influx correlates with the proportion of cells in cultures of inducible Friend cell clones which later go on to synthesize hemoglobin. Compounds which do not incude differentiation in these cells, such as xanthine, exogenous hematin, and erythropoietin, do not cause a change in 86Rb+ influx. A change in the intracellular K+ ion concentration does not occur during induction by DMSO because, although there is a decrease in K+ content per cell soon after induction, there is a parallel decrease in cell volume. These results and previous observations from this laboratory are discussed in terms of the posible involvement of the Na+/K+ ATPase in Friend cell differentiation.