On biaccessible points in the Julia set of a Cremer quadratic polynomial

We prove that the only possible biaccessible points in the Julia set of a Cremer quadratic polynomial are the Cremer fixed point and its preimages. This gives a partial answer to a question posed by C. McMullen on whether such a Julia set can contain any biaccessible point at all.

     

Application of capillary electrochromatography (CEC) for the analysis of phenols in mainstream and sidestream tobacco smoke

Summary This paper describes the application of capillary electrochromatography (CEC) to the rapid quantitative analysis of individual mono- and dihydroxy phenols in tobacco smoke. The method derived provides reproducible and quantitative analysis of real samples, in significantly shorter times than are achieved by current GC and HPLC methods.     

Application of Spectroscopy and Microscopy Techniques in Surface Coatings Evaluation: A Review

Abstract: This article presents a review of the published articles related to the novel application of spectroscopy and microscopy methods in paint and coatings quality evaluation. Traditional and simple techniques have been used in paint and coating industry for many years and proven to be effective. However, the paint and coating industry faces new formulations with nontraditional applications. Therefore, the industry needs to adjust itself with the current sophisticated production and testing methods. There are a number of modern microscopy and spectroscopy techniques that can be utilized in the paint and coating industry for a better understanding of the product quality and/or application performance. This, in particular, is highly applicable in modern and nontraditional applications such as nanotechnology and smart coatings. Though importance of spectroscopy and microscopy methods is being increasingly recognized in the industry, there is no current comprehensive review available to highlight the need for novel application of these techniques in surface coatings evaluations.     

Palladium-catalyzed stereoselective synthesis of 3-(aminomethylene)-oxindoles

An efficient palladium-catalyzed protocol for the stereoselective synthesis of 3-(aminoarylmethylene)-oxindoles has been developed. In this approach, Ugi-4-component reaction adducts were used as starting materials for carbopalladative cyclization-Buchwald reaction sequences.     

Evaluation of chromatographic and spectroscopic methods for the analysis of petroleum-derived compounds in the environment

Summary Analytical protocols have been adapted for the study of hydrocarbons at the trace level in the environment. Various samples, including sediments and biota, were collected from the Kuwaiti environment, treated according to the protocol and analyzed by chromatographic and spectroscopic methods. The methods used were synchronous scanning fluorescence spectroscopy (SSFS); high-performance liquid chromatography (HPLC) on C18 reversed-phase and NH2 normal-phase columns with UV and fluorescence detectors; gas chromatography on fused-silica capillary columns (GC) with flame ionization detector (FID), mass spectrometer (MS) and flame photometric detector (FPD); and high-resolution molecular spectrofluorimetry in Shpol'skii matrix at 10 K (HRSS). The different methods were found to give complementary information. SSFS was useful for fast evaluation and preliminary assessment of oil pollution during extended programs; it permitted sample selection for deeper analyses but, when applied to biota, needed special care in the clean-up procedure. GC/FID, was used to analyze saturated and ethylenic compounds and was useful for obtaining information on the origin of hydrocarbons but inconvenient for analyzing the aromatic fraction. GC/FPD was difficult to use with sediment samples and yielded little information on biota samples, although it did permit confirmation of high oil contamination in some examples. HPLC on a normal-phase column with UV and fluorescence detectors was useful for the fractionation of samples and for the separation of different families of aromatic compounds according to aromatic carbon number. GC/MS was used to quantify polycyclic aromatic hydrocarbons (PAHs) of less than four cycles but was not sensitive enough for PAHs of higher molecular weight. HRSS, however, was useful for the quantification of heavy PAHs and was also faster, could be automated, and gave accurate results. However, in an oil-pollution study, it must be backed up by the other techniques. In fact, no single analytical technique was found to be sufficient, and only judicious combinations of the tested techniques yielded adequate information on the origin of hydrocarbons in the environment.     

Synthesis and properties of carbamate‐ and amine‐containing poly(phenylacetylenes)

The 3‐ and 4‐aminophenylacetylenes protected by t‐butoxycarbonyl (t‐Boc) and 9‐fluorenylmethoxycarbonyl (Fmoc) groups ( 3a – 6a ) were synthesized and polymerized using [(nbd)RhCl]₂ ( 1 ) and [(nbd)Rh⁺‐η⁶‐PhB^?Ph₃] ( 2 ) catalysts. The t‐Boc‐containing polymers [poly( 3a ) and poly( 4a )] were obtained in high yield (82–91%). Among the Fmoc‐protected monomers, the para‐derivative polymerized well [poly( 6a ); yield = 85–94%], whereas its meta‐substituted analogue did not afford high molecular weight polymer in good yield [poly( 5a ); yield = 10–15%]. The use of KN(SiMe₃)₂ as a cocatalyst in conjunction with 1 led to a dramatic increase in the molecular weight of the polymers. The acid‐ and base‐catalyzed removal of the t‐Boc and the Fmoc groups, respectively, generated primary amine‐containing polymers [poly( 3b )–poly( 6b )] which cannot be obtained directly by the polymerization of the corresponding monomers. The solubility characteristics of the polymers bearing protected amino groups were quite different from those of the unprotected ones, the former being soluble in polar solvents, whereas the latter displayed poor solubility even in polar protic or highly polar aprotic solvents. The attempts to accomplish the free‐standing membrane fabrication by solution casting were successful only for poly( 3a ), and an augmentation in the gas permeability and CO₂/N₂ permselectivity was discerned in comparison with the unsubstituted poly(phenylacetylene) and poly(m‐t‐butyldimethylsiloxyphenylacetylene). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1853–1863, 2009     

Calixarene Dimers as Host Molecules for Biologically Important Di‐ and Oligophosphates

A dimeric calixarene, with an aliphatic C₆‐bridge and six anilinium head groups at its upper rim, preferably complexes diphosphates and oligonucleotides with more than 10 bonds between both anionic moieties. Free binding energies correlate with the length of the aliphatic bridge in a roughly linear fashion. The binding event, which is monitored by fluorescence titrations and competition experiments, relies on Coulomb interactions, as opposed to a nonpolar variant with tert‐butyl instead of ammonium groups; here, hydrophobic forces prevail, rendering the calixarene dimer selective for less polar cofactors such as FAD. The best guest for the hexaanilinium dimer is found in ssDNA, which carries multiple copies of the optimal trinucleotide for maximum attraction towards the extended cationic host. The recognition event is also observed in the environment of a lipid monolayer, and provides a means to quantify dimer diphosphate interactions by measuring p/A shifts.     

Equation of state of finite-size hadrons: thermodynamical consistency

A method is presented to derive hadronic gas equation of state incorporating the effect of finite size of baryons in a thermodynamically consistent way. The model contains a more realistic picture of incorporating the effect of excluded volume unlike earlier methods. The results obtained by our calculation and those by the thermodynamically inconsistent methods used in many earlier works are compared.     

Structure-toxicity relationships of thiono and seleno phosphoramidate compounds: new type of acetylcholinesterase inhibitors

Novel thiono and seleno phosphoramidate compounds with the general formula (X)(Y)P(C₆H₅)₂; (X = NMe₂ & Y = S, 1a; X = NEt₂ & Y = S, 2a; X = NMe(CH₂Ph) & Y = S, 3a; X = NH(CH₂Ph) & Y = S, 4a; X = NEt(CH₂Ph) & Y = S, 5a; X = N(C(Me)₃) (CH₂Ph) & Y = S, 6a; X = N(CH₂Ph)₂ & Y = S, 7a; X = NMe₂ & Y = Se, 1b; X = NEt₂ & Y = Se, 2b; X = NMe(CH₂Ph) & Y = Se, 3b; X = NH (CH₂Ph) & Y = Se, 4b; X = NEt(CH₂Ph) & Y = Se, 5b; X = N(C(Me)₃)(CH₂Ph) & Y = Se, 6b and X = N(CH₂Ph)₂ & Y = Se, 7b) were prepared and characterized by ¹H, ³¹P and ¹³C NMR and IR spectroscopy and elemental analysis. ³¹P chemical shift of thiono and seleno derivatives didn’t show significant different because of their little difference in electronegativity sulfur and selenium. Hydrophobic parameter of compounds was determined by measurement of octanol-water partition coefficient by shake-flask technique. Determination of human erythrocyte acetylcholinesterase (hAChE) activity was carried out according to the Ellman’s modified kinetic method. IC₅₀ values of the selected thiono and seleno compounds varied from 3.4 to 0.11 and 9.9 to 5.1 mM, respectively. The seleno compounds show lower affinities for hAChE relative to the thino compounds. These results demonstrate that hydrophobic and electronic factors of the organophosphorus compounds play a key role on the inhibitory potency.