Abstract  The study was aimed at examining the effects of tert-butyl hydroperoxide (tBHP) on hepatic transcriptome expression patterns of the teleost fish Lithognathus mormyrus. tBHP is an organic hydro-peroxide, widely used as a model pro-oxidant. It generates the reactive oxygen species (ROS) tert-butoxyl and tert-butylperoxyl. Complementary DNAs of tBHP-treated vs control fish were applied onto a previously produced cDNA microarray of approximately 1500 unique sequences. The effects of the tBHP application were demonstrated by leukocyte infiltration into the liver and by differential expression of various genes, some already known to be involved in ROS-related responses. Indicator genes of putative ROS effects were: aldehyde dehydrogenase 3A2, Heme oxygenase and the hemopexin-like protein. Putative indicators of transendothelial leukocyte migration and function were: p22phox, Rac1 and CD63-like genes. Interestingly, 7-dehydrocholesterol reductase was significantly down-regulated in response to all treatments. Several non-annotated genes revealed uniform directions of differential expression in response to all treatments.

Abstract  Three novel compounds, together with five known ingredients, octacosanol, 3',4',5-trihydroxy-3,7-dimethoxyflavone, 3,4-dihydroxybenzaldehyde, isorhamnetin, and ent-kaurane-3beta,16beta,17-triol, were obtained from the leaves of Smallanthus sonchifolius (yacon), and their structures were elucidated as ent-kaurane-3beta,16beta,17,18-tertol (1), 3R,7E-9-butoxyl-megastigma-3-ol-3-O-beta-D-glucopyranoside (2), and 3S,5R,6Z-megastigma-6-en-3,5,8,9-tertol (3) on the basis of spectroscopic and chemical methods.

Abstract  Theoretical models have been used to derive rate coefficients for the unimolecular reaction pathways of two prototypical alkoxyl radicals (1-butoxyl and 2-pentoxyl) which can undergo 1,5 H-shift isomerisation yielding the corresponding delta-hydroxy alkyl radical. Special emphasis has been given to the contribution of tunnelling in the isomerisation channels which has not been accounted for in previous theoretical studies. The combination of high level ab initio calculations with a fully coupled multiple channel master equation (ME) treatment resulted in a significant increase of the isomerisation rates by about a factor of 2.7 for the 1-butoxyl and 2.3 for the 2-pentoxyl radical, respectively, as compared to calculations in which tunnelling was neglected, even at 298 K. The corresponding Arrhenius energies in the temperature range from 200 up to 1000 K are significantly smaller when tunnelling is accounted for and differ from previous results which focused only on temperatures around 298 K. The rate expressions derived for the 1,5 H-shift isomerisation reactions are: k(iso,1but) = 1.58 x 10(12)(T/300 K)(-2.30) exp(-4679 K/T) s(-1) and k(iso,2pent) = 4.65 x 10(12)(T/300 K)(-3.22) exp(-4782 K/T) s(-1) valid for p = 1013 mbar and temperatures between 200 K < or = T < or = 1000 K. Our results are strongly supported by recent experiments of Cox and co-workers, (D. Johnson, P. Cassanelli, and R. A. Cox, J. Phys. Chem. A, , 2004, 108, 519 and P. Cassanelli, D. Johnson, and R. A. Cox, Phys. Chem. Chem. Phys. 2005, 7, 3702, 18) which are among the very few studies performed in a temperature regime (250 < or = T < or = 320 K) where tunnelling is thought to be effective. Since tunnelling has been neglected so far in the theoretical analysis of experimental data, the reliability of existing extrapolations to higher and lower temperatures is discussed in detail.

Abstract  Using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trap, alkoxyl radicals and peroxyl radicals produced from the reactions of tert-butyl hydroperoxide(tBuOOH) and cumene hydroperoxide (PhC(CH3)2OOH) with some copper(Cu)(II) complexes such as Cu(II) complexes of cimetidine (Cim), cyclo(L-histidyl-L-histidyl) (CyHH), L-histidylglycine (HG), and L-histidylglycylglycine (HGG) were detected by electron spin resonance (ESR) spectroscopy. However, Cu(II) complexes of glycyl-L-histidine (GH), glycyl-L-histidylglycine (GHG),glycylglycyl-L-histidine (GGH), and glycylglycyl-L-histidyl-glycine (GGHG) did not cause the generation of free radicals during the reaction with tert-butyl or cumene hydroperoxide. Addition of a biological reductant such as cysteine or glutathione to the system including these Cu(II) complexes and hydroperoxides gave tert-butoxyl and cumyl alkoxyl (RO.) radicals, respectively. These alkoxyl radicals underwent subsequent beta-scission reaction and generated the carbon-centered radical (R.). Although cysteine and glutathione are considered to be cellular antioxidants, our results suggest that these biological reductants facilitate Cu(II) complexes-dependent free radical generation.

Abstract  Solvent effects on the AIBN and ACVA forced degradation of cumene are explored. The degradant formation rates of the three cumene oxidative degradants, cumene hydroperoxide, acetophenone, and 2-phenyl-2-propanol are reported. The relative abundance and ratios of these three degradants provide insight into the fate of the peroxy radical oxidants generated by the forced stress system, and suggest that alkoxy radicals are actually a significant source of the observed reactivity. The presence of even 1% methanol in the forced stress solvent significantly quenches this alkoxy radical reactivity, dramatically reducing the overall degradation rate and leaving cumene hydroperoxide as the major product of the oxidation reaction. The origin of this significant solvent effect on the oxidation product distribution is shown to be related to the preferential H-atom abstraction from methanol and its trace impurities by any alkoxy radicals present in the reaction solution. The implications for these observations are explored with the intent of producing more predictive oxidative forced stress experiments.

Abstract  Laser flash photolysis and competitive techniques have been employed to study the reactions of alpha-tocopherol with various radicals and ketone triplets in solution. For example benzophenone triplets abstract hydrogen with rate constants of 5.1 x 10(9) and 3.7 x 10(9) M-1 s-1 in benzene and benzene/1.3 M methanol. Similar near-diffusion-controlled values were obtained for several other ketone triplets, as well as tert-butoxyl and 4-methoxybenzoyloxyl radicals. Deuterium kinetic isotope effects are frequently very small, reflecting the expected lack of selectivity of fast reactions. The reactivity of the 5-hexenyl radical toward alpha-tocopherol was examined by studying the competition of this process with the radical cyclization to the cyclopentylmethyl radical. The value of (1.7 +/- 0.2) x 10(6) M-1 s-1 (at 70-degrees-C in benzene) for this hydrogen atom abstraction from alpha-tocopherol makes this process exceptionally fast in comparison with the limited available rate data for reactions of carbon-centered radicals with other phenols.

Abstract  3-(2-amino-ethyl)-5-[3-(4-butoxyl-phenyl)-propylidene]-thiazolidine-2,4-dione (K145) is identified as a selective SphK2 inhibitor. It was previously reported as an anti-tumor agent, in this study we demonstrated that K145 was able to regulate hepatic gluconeogenesis and improve glucose intolerance in mice. C57BL/6 mice treated with dexamethasone injection were used as experimental animals, which exhibited impaired glucose tolerance and increased gluconeogenetic enzymes. After K145 treatment, we found that the impairment of glucose tolerance and gluconeogenetic genes mRNA expression were improved. Besides, both in vivo and in votro studies suggested that K145 stimulated insulin dependent Akt phosphorylation and subsequently activates FoxO1 phosphorylation therefore inhibited gluconeogenetic genes expression including PEPCK and G6pase. Our study figures out a potential extent increase the value of developing K145 as therapeutic candidate for diabetes.

Abstract  Diamagnetic metal complexes of phthalocyanines with n-butoxyl groups in all the α-benzo positions of the macrocycle skeleton, MPc(OBu)8, have strong near-infrared absorptions and intense fluorescences that are Stokes shifted by more than 15 nm. Interestingly, the silicon complex 6 is also remarkably photostable and nontoxic. The use of 6 in the fluorescence imaging of BALB/c mice bearing a 4T1-luc2 tumor in the mammary fat pad unambiguously revealed the presence of the tumor when it was only 1 mm in diameter and was not visible with the naked eye. Compound 6 has an intrinsic ability to accumulate in the tumor, adequate spectroscopic properties, and excellent stability to function as a NIR fluorescent label in the early detection of tumors.

Abstract  The murine KRAS promoter contains a G-rich nuclease hypersensitive element (GA-element) upstream of the transcription start site that is essential for transcription. Pulldown and chromatin immunoprecipitation assays demonstrate that this GA-element is bound by the Myc-associated zinc finger (MAZ) and poly(ADP-ribose) polymerase 1 (PARP-1) proteins. These proteins are crucial for transcription, because when they are knocked down by short hairpin RNA, transcription is down-regulated. This is also the case when the poly(ADP-ribosyl)ation activity of PARP-1 is inhibited by 3,4-dihydro-5-[4-(1-piperidinyl) butoxyl]-1(2H) isoquinolinone. We found that MAZ specifically binds to the duplex and quadruplex conformations of the GA-element, whereas PARP-1 shows specificity only for the G-quadruplex. On the basis of fluorescence resonance energy transfer melting and polymerase stop assays we saw that MAZ stabilizes the KRAS quadruplex. When the capacity of folding in the GA-element is abrogated by specific G --> T or G --> A point mutations, KRAS transcription is down-regulated. Conversely, guanidine-modified phthalocyanines, which specifically interact with and stabilize the KRAS G-quadruplex, push the promoter activity up to more than double. Collectively, our data support a transcription mechanism for murine KRAS that involves MAZ, PARP-1 and duplex-quadruplex conformational changes in the promoter GA-element.

Abstract  Poly(ADP-ribose)polymerase-1 (PARP-1) is thought to be required for apoptosis-inducing factor (AIF) release from mitochondria in caspase-independent apoptosis. The mechanism by which AIF is released through PARP-1 remains unclear. Here, we provide evidence that PARP-1-independent AIF release and cell death are induced by a trienoic fatty acid, alpha-eleostearic acid (alpha-ESA). Alpha-ESA induced the caspase-independent and AIF-initiated apoptotic death of neuronal cell lines, independently of PARP-1 activation. The cell death was inhibited by the MEK inhibitor U0126 and by knockdown of MEK using small interfering RNA. However, inhibitors for JNK, p38 inhibitors, calpain, phospholipase A(2), and phosphatidylinositol 3-kinase, did not block cell death. AIF was translocated to the nucleus after the induction of apoptosis by alpha-ESA in differentiated PC12 cells without activating caspase-3 and PARP-1. The alpha-ESA-mediated cell death was not inhibited by PARP inhibitor 3,4-dihydro-5-[4-(1-piperidinyl)butoxyl]-1(2H)-isoquinoline and by knockdown of PARP-1 using small interfering RNA. Unlike N-methyl-N'-nitro-N-nitrosoguanidine treatment, histone-phosphorylated histone 2AX was not phosphorylated by alpha-ESA, which suggests no DNA damage. Overexpression of Bcl-2 did not inhibit the cell death. alpha-ESA caused a small quantity of superoxide production in the mitochondria, resulting in the reduction of mitochondrial membrane potential, both of which were blocked by a trace amount of alpha-tocopherol localized in the mitochondria. Our results demonstrate that alpha-ESA induces PARP-1-independent AIF release and cell death without activating Bax, cytochrome c, and caspase-3. MEK is also a key molecule, although the link between ERK, AIF release, and cell death remains unknown. Finding molecules that regulate AIF release may be an important therapeutic target for the treatment of neuronal injury.

Abstract  A new kind of amphiphilic derivative of carboxymethylchitosan, a group of (2-hydroxyl-3-butoxyl)propylcarboxymethylchitosans (HBP-CMCHS), has been synthesized, and the surface and aggregate properties have been studied by means of surface tension, surface pressure and fluorescence measurements. HBP-CMCHS can adsorb on the surface to decrease the surface tension of the solution. The adsorption film was quite stable, which can make the relative compressed pressure increase dramatically with the decrease of the surface area. In solution, hydrophobic aggregations were identified by the decrease in the ratio of the fluorescence emission intensity of the first and third pyrene vibronic peaks ( I(1)/ I(3)). Results showed that the aggregation began to form at a concentration similar to that of the polymer transfer to the air-water interface. Aggregate formation of the polymers is a gradually compact process with hydrophobic associations. Increase of DS and addition of NaCl to the HBP-CMCHS solution can make the surface tension decrease, make the aggregation occur at lower concentration, and make the aggregation more hydrophobic.

Abstract  As we reported previously, hypochlorite interacting with organic hydroperoxides causes their decomposition ((1995) Biochemistry (Moscow), 60, 1079-1086). This interaction was supposed to be a free-radical process and serve as a source of free radicals initiating lipid peroxidation (LP). The present study is the first attempt to detect and identify free radicals produced in the reaction of hypochlorite with tert-butyl hydroperoxide, (CH3)3COOH, which we have used as an example of organic hydroperoxides. We have used a direct method for free radical detection, EPR of spin trapping, and the following spin traps: N-tert-butyl-alpha-phenylnitrone (PBN) and alpha-(4-pyridyl-1-oxyl)-N-tert-butylnitrone (4-POBN). When hypochlorite was added to (CH3)3COOH in the presence of a spin trap, an EPR spectrum appeared representing a superposition of two signals. One of them belonged to a spin adduct formed as a result of direct interaction of hypochlorite with the spin trap (hyperfine splitting constants were: abetaH = 0.148 mT; aN = 1.537 mT; and deltaHPP = 0.042 mT for 4-POBN and abetaH = 0.190 mT; aN = 1.558 mT; and deltaHPP = 0.074 mT for PBN). The other signal was produced by hypochlorite interactions with (CH3)3COOH itself (hyperfine splitting constants were: abetaH = 0.233 mT; aN = 1.484 mT; deltaHPP = 0.063 mT and abetaH = 0.360 mT; aN = 1.547 mT; deltaHPP = 0.063 mT for 4-POBN and PBN, respectively). Comparison of spectral characteristics of this spin adduct with those of tert-butoxyl or tert-butyl peroxyl radicals produced in known reactions of (CH3)3COOH with Fe2+ and Ce4+, respectively, showed that the radical (CH3)3COO* is produced from the interaction of hypochlorite with (CH3)3COOH. Like Ce4+ but not Fe2+, hypochlorite addition to (CH3)3COOH was accompanied by a bright flash of chemiluminescence characteristic of the reactions in which peroxyl radicals are produced. Thus, all these results suggest peroxyl radical production in the reaction of hypochlorite with hydroperoxide. This reaction is one of the most possible ways for the initiation of free-radical LP that occurs in vivo, when hypochlorite interacts with unsaturated lipids comprising natural protein-lipid complexes, such as lipoproteins and biological membranes.

Abstract  The effects of LY-171883, an orally active leukotriene antagonist, on membrane currents were examined in pituitary GH(3) and in neuroblastoma IMR-32 cells. In GH(3) cells, LY-171883 (1-300 microM) reversibly increased the amplitude of Ca(2+)-activated K(+) current in a concentration-dependent manner with an EC(50) value of 15 microM. In excised inside-out patches recorded from GH(3) cells, the application of LY-171883 into cytosolic face did not modify single channel conductance of large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels; however, it did increase the channel activity. The LY-171883-stimulated activity of BK(Ca) channels is dependent on membrane potential, and results mainly from an increase in mean open time and a decrease in mean closed time. However, REV-5901 (30 microM) suppressed the activity of BK(Ca) channels and MK-571 (30 microM) did not have any effect on it. Under the current-clamp condition, LY-171883 (30 microM) caused membrane hyperpolarization as well as decreased the firing rate of action potentials in GH(3) cells. In neuroblastoma IMR-32 cells, the application of LY-171883 (30 microM) also stimulated BK(Ca) channel activity in a voltage-dependent manner. However, neither clofibrate (30 microM) nor leukotriene D(4) (10 microM) affected the channel activity in IMR-32 cells. Troglitazone (30 microM) decreased the channel activity, but ciglitazone (30 microM) enhanced it. This study clearly demonstrates that LY-171883 stimulates the activity of BK(Ca) channels in a manner unlikely to be linked to its blockade of leukotriene receptors or stimulation of peroxisome proliferator-activated receptors. The stimulatory effects on these channels may, at least in part, contribute to the underlying cellular mechanisms by which LY-171883 affects neuronal or neuroendocrine function.

Abstract  When rat liver mitochondria are treated with tert-butyl hydroperoxide (TBHP) in the presence of the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO), electron paramagnetic resonance (EPR) signals are detected attributable to spin adducts resulting from the trapping of methyl, tert-butoxyl, and tert-butylperoxyl radicals. The addition of respiratory substrate results in a 3- to 7.5-fold increase in the signal intensity of the DMPO/methyl adduct, no change in the signal intensity of the DMPO/tert-butoxyl adduct, and complete loss of the DMPO/tert-butylperoxyl adduct signal. The magnitude of increase of methyl radical production in the presence of respiratory substrate is related to the respiratory control ratio (RCR) of the mitochondrial preparation. In the presence of antimycin A, which blocks electron flow between cytochromes b and c1, no stimulation of methyl radical production is detected with respiratory substrate. Stimulation of methyl radical production by the addition of respiratory substrate is detected in cytochrome c-depleted mitochondria. A similar increase in methyl radical production is detected when ferrous cytochrome c is treated with TBHP in the presence of DMPO (as compared to when ferricytochrome c is used). These results indicate that TBHP is reduced directly by either cytochrome c1, cytochrome c, or by both of these electron transport chain components in mitochondria undergoing state 4 respiration.

Abstract  In order to understand the conversion mechanism of fatty acids to long-chain alkanes using molybdenum carbide as a catalyst, the full potential energy surface of the hydrogenation of butyric acid to butane on the H-pre-covered hexagonal Mo2C(101) surface has been systematically computed on the basis of density functional theory including dispersion (PBE-D3) and zero-point energy corrections. The first step of the reaction is butyric acid dissociation into surface OH and acyl [R-COOH + H = R-CO + OH + H], followed by the formation of butanal from acyl hydrogenation [R-CO + OH + H = R-CHO + OH]. The second step of the reaction is butanal hydrogenation into butanol via the surface butoxyl intermediate [R-CHO + H + OH = R-CH2O + OH; R-CH2O + H + OH = R-CH2OH + OH]. The third step is butanol dissociation into surface OH and butyl [R-CH2OH + H = R-CH2 + OH + H], which is further hydrogenated into butane [R-CH2 + H + OH = R-CH3 + OH]. The formation of butanal and butanol as intermediates in equilibrium as well as butane as the final product is in full agreement with the experiment of stearic acid hydrodeoxygenation into octadecane. For the conversion, butanol dissociation [R-CH2OH + H = R-CH2 + OH + H] has the highest barrier and represents the rate-determining step. It is noted that the metallic Mo2C(001) surface can bind surface H2O, OH and O much more strongly than the Mo2C(101) surface with exposed Mo and C atoms (C/Mo = 1). Since our results are obtained only from the most stable Mo2C(101) surface, they cannot correlate with the whole experimentally observed reactivity and selectivity of different Mo2C phases with different surface terminations. Nevertheless, our results provide the basis for exploring the intrinsic nature of Mo2C catalysts in deoxygenation of oxygenates involved in the refining of biomass-derived oils.

Abstract  When the mixture of titanium tetrabutoxide [Ti(OC4H9)(4)] and acetic anhydride [(CH3CO)(2)O] was heated in cyclohexane, two butoxyl groups ( OC4H9) in Ti(OC4H9)(4) were replaced easily so as to form titanium dibutoxide diacetate [Ti(OC4H9)(2) (OOCCH3)(2)] and butyl acetate (CH3COOC4H9). In plenty of (CH3CO)(2)O, Ti(OC4H9)(2)(OOCCH3)(2) was transformed into two kinds of titanyl organic compounds with different structure, titanyl diacetate [TiO(OOCCH3)(2)] and titanyl dibutoxide tetraacetate [Ti2O(OC4H9)(2)(OOCCH3)(4)] that all contain Ti-O-Ti structure units. Titanium dibutoxide diacetate could be dissolved in organic solvent but titanyl organic compounds could not. Titanyl dibutoxide tetraacetate was decomposed more easily by heating than titanyl diacetate.

Abstract  Arsenic and polycyclic aromatic hydrocarbon (PAH) exposures affect many people worldwide leading to cancer and other diseases. Arsenite (As(+3)) and certain PAHs are known to cause genotoxicity. However, there is limited information on the interactions between As(+3) and PAHs at environmentally relevant concentrations. The thymus is the primary immune organ for T cell development in mammals. Our previous studies showed that environmentally relevant concentrations of As(+3) induce genotoxicity in mouse thymus cells through Poly(ADP-ribose) polymerase (PARP) inhibition. Certain PAHs, such as the metabolites of benzo(a)pyrene (BaP), are known to cause DNA damage by forming DNA adducts. In the present study, primary mouse thymus cells were examined for DNA damage following 18 hr in vitro treatments with 5 or 50 nM As(+3) and 100 nM BaP, benzo[a]pyrene-7,8-dihydrodiol (BP-Diol), or benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE). An interactive increase in genotoxicity and apoptosis were observed following treatments with 5 nM As(+3) + 100 nM BP-diol and 50 nM As(+3) + 100 nM BPDE. We attribute the increase in DNA damage to inhibition of PARP inhibition leading to decreased DNA repair. To further support this hypothesis, we found that a PARP inhibitor, 3,4-dihydro-5[4-(1-piperindinyl) butoxyl]-1(2H)-isoquinoline (DPQ), also interacted with BP-diol to produce an increase in DNA damage. Interestingly, we also found that As(+3) and BP-diol increased CYP1A1 and CYP1B1 expression, suggesting that increased PAH metabolism may also contribute to genotoxicity. In summary, these results show that the suppression of PARP activity and induction of CYP1A1/CYP1B1 may act together to increase DNA damage produced by As(+3) and PAHs.

Abstract  The effect of the presence of photosensitizers, methylene blue (MB) and rose Bengal (RB), on the degradation of carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate) in water in a solar photocatalytic system was investigated. It was found that as compared to MB, RB generally showed a stronger effect on the decomposition of carbofuran under comparable conditions. Among the conditions studied, adding 2 x 10(-6) M of RB, that corresponding to 2% of the initial concentration of carbofuran solution in the system, rendered the most effective degradation of carbofuran. As a result, a carbofuran removal percentage of 69.9%, a mineralization efficiency of 28.0%, and a microtoxicity reduction of 65.0% could be achieved. The degradation and mineralization of carbofuran was found to follow the pseudo-first order reaction kinetics. The decomposition mechanism of carbofuran was further investigated through identification of the intermediates to elaborate the influence of dye photosensitizer on the solar photocatalysis of carbofuran in water. On the basis of the intermediates identified, including carbofuran phenol, 3-hydroxy carbofuran phenol, and substituted alcohols (3-phenoxy 1-propanol, 2-ethyl 1-hexanol, 2-butoxyl ethanol), it appears that hydrolysis and hydroxylation were the two key mechanisms for decomposing carbofuran during the process of solar photocatalysis with the aid of dye photosensitizer.

Abstract  Oxidative susceptibility testing was performed on a drug substance containing a methoxy-naphthalene moiety. 2,2-azobisisobutyronitrile (AIBN) was employed to initiate peroxy radical oxidation to mimic autoxidation processes. In acetonitrile (ACN)water solvents, three major degradation products are formed. However, addition of small amounts of methanol to the solvent system completely eliminated the observed degradation products. To understand this effect, the structures of the three degradants have been elucidated using nuclear magnetic resonance, liquid chromatographytandem mass spectrometry, and accurate mass Fourier transform ion cyclotron resonance mass spectrometry. One degradant structure definitively proves the degradation resulted from alkoxy radicals (2-cyano-2 propoxy radical) arising from the disproportionation of the tertiary AIBN-derived peroxy radicals, rather than from the intended action of the AIBN peroxy radicals themselves. The reaction occurs over a wide range of AIBN and drug substance concentrations. This protective effect of several percent methanol by volume is rationalized by known methanol H atom donation rates to similar tert-butoxy and cumyloxy radicals (ca. 10 M1 s1) and the high methanol concentration relative to the dilute substrate being investigated. This work confirms recent proposals for addition of at least about 10% methanol to the standard ACNwater AIBN stress testing diluent to insure that only the desired peroxy radical activity is present during the oxidative stress test. (c) 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:15541568, 2013

Abstract  Dye-sensitized solar cells (DSCs) with cobalt-based mediators with efficiencies surpassing the record for DSCs with iodide-free electrolytes were developed by selecting a suitable combination of a cobalt polypyridine complex and an organic sensitizer. The effect of the steric properties of two triphenylamine-based organic sensitizers and a series of cobalt polypyridine redox mediators on the overall device performance in DSCs as well as on transport and recombination processes in these devices was compared. The recombination and mass-transport limitations that, previously, have been found to limit the performance of these mediators were avoided by matching the properties of the dye and the cobalt redox mediator. Organic dyes with higher extinction coefficients than the standard ruthenium sensitizers were employed in DSCs in combination with outer-sphere redox mediators, enabling thinner TiO(2) films to be used. Recombination was reduced further by introducing insulating butoxyl chains on the dye rather than on the cobalt redox mediator, enabling redox couples with higher diffusion coefficients and more suitable redox potential to be used, simultaneously improving the photocurrent and photovoltage of the device. Optimization of DSCs sensitized with a triphenylamine-based organic dye in combination with tris(2,2'-bipyridyl)cobalt(II/III) yielded solar cells with overall conversion efficiencies of 6.7% and open-circuit potentials of more than 0.9 V under 1000 W m(-2) AM1.5 G illumination. Excellent performance was also found under low light intensity indoor conditions.

Abstract  Theoretical and experimental investigation on the applied electric field-and intensity-dependent photorefractive response in a photorefractive polymeric composite is presented. The decay time constant and the corresponding grating-amplitude for the composite consisting of 1-n-butoxyl-2,5-dimethyl-4-(4'-nitrophenylazo)benzene:poly(N- vinylcarbazole):2,4,7-trinitro-9-fluorenone with a weight ratio 44:55:1 were measured. The results revealed that there existed two gratings simultaneously, one was caused by the photorefractive effect, and the other was contributed from the photo-isomerization process. The dynamic process for the photorefractive grating was explained with a modified band transport model.

Abstract  NOVELS N-BENZOYLTYRAMINES OF Swinglea glutinosa (Rutaceae). Phytochemical studies of the leaves and fruits have led to the identification of the known amides (E)-N-methyl-cinnamamide, N-benzoyltyramine, N-benzoyl-O-geranyltyramine, N-benzoyl-O-(4-acetoxyl)-geranyltyramine, in addition to the new N-{2-[4-(butoxyl-3-one)phenyl]ethyl}benzamide, N-{2-[4-(2,3-dihydroxy-2-methyl-butoxylanal) phenyl] ethyl} benzamide, N-{2-[4-(2,3-dihydroxy-2-methyl-butoxyloic)phenyl]ethyl} benzamide, N-benzoyl-O-(4-acetoxyl-6,7-epoxy)-geranyltyramine, N-benzoyl-O-(4-acetoxyl-6,7-dihydroxy)-geranyltyramine and N-benzoyl-O-(6-acetoxyl-4,7-dihydroxy)-geranyltyramine. The isolated compounds clearly point to Swinglea phytochemical affinities with other Aurantioideae species.

Abstract  Distinct electroabsorption grating and photoisomerization grating as well as photorefractive grating were observed in the composite consisting of 1-n-butoxyl-2,5- dimethyl-4-(4'-nitrophenylazo)benzene (BDMNPAB): poly(N-vinylcarbazole) (PVK):2,4,7-trinitro-9-fluorenone (TNF) in a weight ratio of 44:55:1. Based on the quick translation technique of two-beam coupling experimental geometry, we measured the electroabsorption grating to be 6 similar to 7 cm(-1), and photoisomeric effect also brought an absorption grating of 2 similar to 3 cm(-1). Photoisomeric effect caused index grating was separated from the others by analyzing the dynamic behaviour of the gratings, and an amplitude between 1 x 10(-4)similar to 2 x 10(-4) was obtained.

Abstract  Three-component is a promising direction to overcome disadvantages (e.g., unstability and critical environment requirement) of the four-component low glass transition temperature photorefractive (PR) polymer composite which consists of photosensitizer, nonlinear optical (NLO) chromophore, charge transport agent, and the plasticizer separately. Based on the well-known hole photoconductive network of poly(N-vinylcarbazole):2,4,7-trinitro-9-fluorenone, in our presented investigations, several well-performanced three-component PR composites were developed for different application purposes with the optimal designing optical chromophore exhibit both NLO response and plasticizing property. Generally, it is expected that long chain alkoxy of the chromophore may increase the plasticizing property while long alkoxy chain makes itself more easy to curl, which might weaken the plasticizing function, thus an optimum selection of the length of the alkoxy exists. From the experimental observations of 2,5-dimethyl-4-(4'-nitrophenylazo)benzene with different length of the alkoxy, it was indicated that high coupling gain (similar to 195 cm(-1)) and index grating amplitude (similar to 4.3 x 10(-3)) were achieved at 633 nm in the composite contain 1-n-butoxyl-2,5-dimethyl-4-(4'-nitrophenylazo)benzene. Besides, different substituent groups make the chromophore inequal plasticizing and different electrooptic properties. For operating at short wavelength, beta,beta-diacetyl-4-methoxylstyrene is the more suitable selection (with a coupling gain of similar to 38 cm(-1) at 543 nm, which is higher than these at 593 nm, 612nm and 633 nm). Doped with beta,beta-diacetyl-4-methoxylstyrene, a response time as short as similar to 17 ms at illumination intensity of 1 W/cm(2) at the wavelength of 633 nm was estimated, which is the most fast response reported up to now and can be used in real-time optical information processing. On the other hand, all composites mentioned above have long lifetime and high stability.