The effect of fluorine-based plasma treatment on morphology and chemical surface composition of biocompatible silicone elastomer

X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) have been used to investigate the effect of reactive ion etching (RIE) on poly(methylhydrogensiloxane-co-dimethylsiloxane) surface in fluorine-based plasmas. Polysiloxane layers supported on the standard silicon wafers were etched using SF₆ + O₂ or CF₄ + O₂ plasmas. SEM studies show that the polysiloxane morphology depends on plasma chemical composition strongly. Presence of a columnar layer likely covered with a fluorine rich compound was found on the elastomer surface after the CF₄ + O₂ plasma exposure. After the SF₆ + O₂ or CF₄ + O₂ plasma treatment the polysiloxane surface enriches with fluorine or with fluorine and aluminum, respectively. Different morphologies and surface chemical compositions of the silicone elastomer etched in both plasmas indicate different etching mechanisms.     

Sensitised decomposition of microcystin-LR using UV radiation

UV radiation was applied to degrade cyanobacterial hepatotoxin, microcystin-LR in the presence of phycocyanin as a model natural sensitiser. The concentrations of both the toxin and the pigment used in the experiments were higher by several orders of magnitude than found in the environment. The photoreaction parameters were optimised. The process was found to be of limited use for water treatment due to its low efficacy. Additionally, pronounced UV-induced bleaching of the pigment significantly reducing the photoreaction rates of the toxin was observed for the highest UV radiation intensities applied.     

PHOTOCYTOTOXICITY OF CURCUMIN

Curcumin, bis (4-hydroxy-3-methoxyphenyl)-l,6-diene-3,5-dione, is a yellow-orange dye derived from the rhizome of the plant Curcuma longa. Curcumin has demonstrated phototoxicity to several species of bacteria under aerobic conditions (Dahl, T. A., et al. , 1989, Arch. Microbiol. 151 183), denoting photodynamic inactivation. We have now found that curcumin is also phototoxic to mammalian cells, using a rat basophilic leukemia cell model, and that this phototoxicity again requires the presence of oxygen. The spectral and photochemical properties of curcumin vary with environment, resulting in the potential for multiple or alternate pathways for the exertion of photodynamic effects. For example, curcumin photogenerates singlet oxygen and reduced forms of molecular oxygen under several conditions relevant to cellular environments. In addition, we detected carbon-centered radicals, which may lead to oxidation products (see accompanying paper). Such products may be important reactants in curcumin's phototoxicity since singlet oxygen and reduced oxygen species alone could not explain the biological results, such as the relatively long lifetime (t¹²= 27 s) of the toxicant responsible for decreased cell viability.     

Boson-fermion duality in four dimensions: Comments on the paper of luther and schotte

The Fock space for the fermion field can be identified with the Fock space for the boson field, provided the overall numbers of internal degrees of freedom are the same. As a consequence, the respective free field Hamiltonian systems are equivalent (dual): the four-component neutrino model is thus equivalent to the doublet of independent (electric and magnetic, respectively) Maxwell fields, which are quantized in the Coulomb gauge. This statement arises on the field theory level, and seems to make doubtful the claim that realistic photons can be constructed from (bound) neutrino pairs: each (anti)neutrino degree should be represented by the photon-type (electric and magnetic, respectively) degree of freedom.     

Preparation of unsymmetrical disulfides by using sulfines1

Acidolytic cleavage of unsymmetrically substituted dithioacetal monoxides, ArCH(SR)S(O)Me has been used to prepare linear unsymmetrical disulfides RSSMe. Disproportionation was suppressed by the addition of a small amount of benzyl mercaptan. The required starting materials were conveniently obtained from appropriately substituted sulfines ArC(=SO)SR and methyl lithium. The following disulfides were prepared: R =n-C₄H₉ (73.5%), n-C₇H₁₅ (78%), Ph (77.3%), AcO(CH₂)₁₀ (81.5%).The unsymmetrical dithioacetal PhCH(SEt)SC₇H₁₅-n gave upon oxidation with one equivalent of peracid a mixture of two dithioacetal monoxides which on treatment with HClO₄ led to three disulfides. This result is discussed in term of the mechanism of acidolysis.     

The synthesis and the solvent and substituent effect on the spectroscopic characteristic of 3-ethyl-2-(p-substitued styryl)benzothiazolium iodides

The photophysical and photochemical properties of p-substitued 2-styryl-ethylbenzothiazolium iodides, possessing different electron-withdrawing or electron-donating groups are described. The dyes were prepared by the condensation of 3-ethyl-2-methylbenzothiazole salts with p-substituted benzaldehydes. The synthesis of suitable substrates is presented as well. We describe here the absorption, emission spectra and the luminescence quantum yield of hemicyanine dyes (SH) measured in 11 different organic solvents of varying polarity. Molecular structure of the synthesized dyes was established by (1)H NMR, electronic absorption and fluorescence spectrometry. The spectral data confirmed that all the compounds exist in E-configuration of their styryl residues. The planar molecular conformation is typical for the compounds with five-membered side aromatic moieties (for example benzothiazole). The compounds possessing N-alkyl substituent in phenyl ring, in contrast to the compounds with other substituents, exhibit low fluorescence quantum yield in THF solution. This indicates that for N-alkyl derivatives the non-radiative processes are much more effective than the radiative ones. The electronic absorption and fluorescence emission spectra of tested dyes demonstrate high sensitivity to the nature of substituent introduced into the aromatic ring.     

Luminescent organoboron quinolate polymers

The synthesis of well-defined luminescent organoboron polymers via a novel three-step procedure starting from silylated polystyrene is reported. Highly selective borylation of poly(4-trimethylsilylstyrene) (PS-Si), followed by replacement of the bromine substituents in poly(4-dibromoborylstyrene) (PS-BBr) with substituted thienyl groups (R = H, 3-hexyl, 5-hexyl), and final introduction of the 8-hydroxyquinolato moiety yields a series of new organoboron quinolate polymers in 67-83% isolated yield. The hexyl-substituted polymers are highly soluble and solution-processable yielding thin films that efficiently emit light at 513-514 nm upon excitation at 395 nm.     

Role of the surface heterogeneity in adsorption of hydrogen ions on metal oxides: theory and simulations

In this article we study the effect of energetic heterogeneity of a crystalline surface on the adsorption of hydrogen ions (protons) from the liquid phase. In particular, we examine the influence of the shape of the adsorption energy distribution on the equilibrium isotherms of hydrogen ions. To that purpose, a few popular distribution functions, including rectangular, exponential, and asymmetric Gaussian are considered. Additionally, multimodal distribution functions, which may correspond to the adsorption on different crystal planes of the oxide, are also used. Lateral interactions between adsorbed charges are modeled using the potential function proposed by Borkovec et al., which accounts also for polarization of the liquid medium. The results presented here are obtained using both Monte Carlo (MC) simulations and theoretical calculations involving Mean Field Approximation (MFA). They indicate that increased energetic heterogeneity of the adsorbing surface may, in general, considerably change the behavior of the adsorption isotherms, regardless of the assumed distribution function. It is also shown that the predictions of the proposed theory are consistent with the data obtained from the MC simulations.     

Supplementation with Magnesium Salts—A Strategy to Increase Nutraceutical Value of Pleurotus djamor Fruiting Bodies

The use of substrates supplemented with minerals is a promising strategy for increasing the nutraceutical value of Pleurotus spp. The current research was performed to analyze the effect of substrate supplementation with magnesium (Mg) salts on the Mg content, biomass, and chemical composition of pink oyster mushroom (Pleurotus djamor) fruiting bodies. Before inoculation, substrate was supplemented with MgCl₂ × 6 H₂O and MgSO₄, both salts were applied at three concentrations: 210, 420, and 4200 mg of Mg per 2 kg of substrate. The harvest period included three flushes. Substrate supplementation with 4200 mg of Mg caused the most significant decrease in mushroom productivity, of about 28% for both Mg salts. The dry matter content in fruiting bodies was significantly lower in the treatment in which 210 mg of Mg was applied as MgSO₄ in comparison to the control. Supplementation effectively increased the Mg content in fruiting bodies of P. djamor by 19–85% depending on the treatment, and significantly affected the level of remaining bioelements and anions. One hundred grams of pink oyster fruiting bodies, supplemented with Mg salts, provides more than 20% of the Mg dietary value recommended by the Food and Drug Administration (FDA); thus, supplementation can be an effective technique for producing mushrooms that are rich in dietary Mg. Although P. djamor grown in supplemented substrate showed lower productivity, this was evident only in the fresh weight because the differences in dry weight were negligible. Mg supplementation increased the antioxidant activity of the fruiting bodies, phenolic compounds, and some amino acids, including L-tryptophan, and vitamins (thiamine and l-ascorbic acid).