Aqueous Phase C-H Bond Oxidation Reaction of Arylalkanes Catalyzed by a Water-Soluble Cationic Ru(III) Complex [(pymox-Me\u3csub\u3e2\u3c/sub\u3e)\u3csub\u3e2\u3c/sub\u3eRuCl\u3csub\u3e2\u3c/sub\u3e]\u3csup\u3e+\u3c/sup\u3eBF\u3csub\u3e4\u3c/sub\u3e\u3csup\u3e-\u3c/sup\u3e

The cationic complex [(pymox-Me2)RuCl2]+BF4− was found to be a highly effective catalyst for the C−H bond oxidation reaction of arylalkanes in water. For example, the treatment of ethylbenzene (1.0 mmol) with t-BuOOH (3.0 mmol) and 1.0 mol % of the Ru catalyst in water (3 mL) cleanly produced PhCOCH3 at room temperature. Both a large kinetic isotope effect (kH/kD = 14) and a relatively large Hammett value (ρ = −1.1) suggest a solvent-caged oxygen rebounding mechanism via a Ru(IV)-oxo intermediate species

Modified sorting technique to mitigate the collateral mortality of trawled school prawns (Metapenaeus macleayi)

The potential for changes to onboard handling practices in order to improve the fate of juvenile school prawns (Metapenaeus macleayi) discarded during trawling were investigated in two Australian rivers (Clarence and Hunter) by comparing a purpose-built, water-filled sorting tray against a conventional dry tray across various conditions, including the range of typical delays before the start of sorting the catch (2 min vs. 15 min). Juvenile school prawns (n= 5760), caught during 32 and 16 deployments in each river, were caged and sacrificed at four times: immediately (T0), and at 24 (T24), 72 (T72), and 120 (T12 0) hours after having been discarded. In both rivers, most mortalities occurred between T0 and T24 and, after adjusting for control deaths (<12%), were greatest for the 15-min conventional treatment (up to 41% at T120). Mixed-effects logistic models revealed that in addition to the sampling time, method of sorting, and delay in sorting, the weight of the catch, salinity, and percentage cloud cover were significant predictors of mortality. Although trawling caused some mortalities and comparable stress (measured as L -lactate) in all school prawns, use of the water tray lessened the negative impacts of some of the above factors across both the 2-min and 15-min delays in sorting so that the overall discard mortality was reduced by more than a third. When used in conjunction with selective trawls, widespread application of the water tray should help to improve the sustainability of trawling for school prawns

Photochemical delivery of nitric oxide.

There remains considerable interest in developing methods for the targeted delivery of nitric oxide and other small molecule bioregulators such as carbon monoxide to physiological targets. One such strategy is to use a "caged" NO that is "uncaged" by excitation with light. Such photochemical methods convey certain key advantages such as the ability to control the timing, location and dosage of delivery, but also have some important disadvantages, such as the relatively poor penetration of the ultraviolet and visible wavelengths often necessary for the uncaging process. Presented here is an overview of ongoing studies in the author's laboratory exploring new photochemical NO precursors including those with nanomaterial antennas designed to enhance the effectiveness of these precursors with longer excitation wavelengths

Vortex nanoliquid in high-temperature superconductors

Using a differential magneto-optical technique to visualize flow of transport currents, we reveal a new delocalization line within the reversible vortex liquid region in the presence of a low density of columnar defects. This line separates a homogeneous vortex liquid, in which all the vortices are delocalized, from a heterogeneous "nanoliquid" phase, in which interconnected nanodroplets of vortex liquid are caged in the pores of a solid skeleton formed by vortices pinned on columnar defects. The nanoliquid phase displays high correlation along the columnar defects but no transverse critical current.Comment: Paper accepted in Physical Review Letters. 5 pages text with 4 figure

From 2,3-Diazabicyclo[2.2.2]oct-2-ene to Fluorazophore-L, a membrane-bound fluorescent probe for antioxidants

The aim of this work was to synthesize and to establish a new fluorescent membrane probe for antioxidants by exploiting the exceptional properties of the long-lived fluorophore 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) alias Fluorazophore-P. The first step was to find an appropriate synthetic route towards a lipophilic derivative of Fluorazophore-P, namely Fluorazophore-L, that should enable an efficient and facile incorporation into model membrane systems. The water-soluble hydroxy-substituted Fluorazophore-H was chosen as a key compound and served as a versatile precursor for various members of the Fluorazophore-family, including Fluorazophore-L. For example, substantial contributions in the synthesis of fluorazophore-labeled peptides to monitor the length-dependence of end-to-end collision rates of polypeptides were done within this work: "A Fluorescence Based Method for Direct Measurement of Submicrosecond Intramolecular Contact Formation in Biopolymers: An Exploratory Study with Polypeptides", R. R. Hudgins, F. Huang, G. Gramlich, W. M. Nau, J. Am. Chem. Soc. 2002, 124, 556-564. (Appendix) In this context, the search for a mild and selective method to substitute a harsh hydrolysis step, led to a study about a photo-cleavable Fluorazophore: "A Photoactivable Fluorophore Based on Thiadiazolidinedione as Caging Group", G. Gramlich, W. M. Nau, Org. Let. 1999, 1, 603-605. (Appendix) Fluorazophore-L (Fluoazophore-L) was designed as a head-labeled palmitic acid derivative. Experiments in homogeneous solution confirmed that Fluoazophore-L preserves its photophysical properties, namely the long-lived fluorescence and the essentially diffusion-controlled reactivity towards α-tocopherol (α-Toc). Its capability to serve as a membrane probe was assessed by air/water monolayer experiments (surface pressure-area isotherms) and preliminary spectroscopic measurements. It could be shown that Fluoazophore-L partitions into monolayers of 1-palmitoyl-2-oleoyl-sn-glycero-3- phosphocholine (POPC) and that even pure Fluoazophore-L forms stable monolayers at the air-water interface thus presents a highly amphiphilic molecule: "A Long-Lived Amphiphilic Fluorescent Probe studied in POPC Air-Water Monolayer and Solution Bilayer Systems", G. Gramlich, J. Zhang, M. Winterhalter, W. M. Nau, Chem. Phys. Lipids 2001, 113, 1-9 (Appendix). The first assignment of Fluoazophore-L in model membranes was a study of its interaction with the water-soluble antioxidant vitamin C, thus examining interfacial reactivity. Singlet-excited Fluoazophore-L was used as a mimic for highly reactive lipid alkoxyl and peroxyl radicals. This work revealed an unexpected inversion of the pHdependent activity pattern, which could be ascribed to an interesting surface effect: "Increased Antioxidant Reactivity of Vitamin C at low pH in Model Membranes", G. Gramlich, J. Zhang, W. M. Nau, J. Am. Chem. Soc. 2002, 124, 11252-11253 (Appendix). Finally, the intrafacial reactivity of α-Toc in liposomes and micelles could be probed by means of Fluoazophore-L. In micelles and in membrane structures a more demanding quenching kinetics than in usual organic solvents arises. In the case of small micelles Poissonian statistics has to be applied while in liposomes a two dimensional diffusion rate limits the maximum reactivity. In this study, the "immobile" probe/quencher pair Fluoazophore-L/α-Toc was used for the first time and the validity of different quenching models was discussed. The resulting diffusion rate constants for α-Toc provide important benchmark values for antioxidant research: "Diffusion of α-Tocopherol in Membrane Models: Probing the Kinetics of Vitamin E Antioxidant Action by Fluorescence in Real Time", G. Gramlich, J. Zhang, W. M. Nau, J. Am. Chem. Soc. 2004, 126, 5482-5492 (Appendix). A global fitting routine was developed to allow appropriate data processing of fluorescence quenching in membrane models. This fitting procedure was also successfully employed in the simultaneous fitting of steady-state and time-resolved fluorescence quenching by host-guest complexation with cyclodextrins. "A Joint Structural, Kinetic, and Thermodynamic Investigation of Substituent Effects on Host- Guest Complexation of Bicyclic Azoalkanes by β-Cyclodextrin", X. Zhang, G. Gramlich, X. Wang, W. M. Nau, J. Am. Chem. Soc. 2002, 124, 254-263 (Appendix). For the quenching models used, it is essential to ensure that reaction between singletexcited fluorazophores and hydrogen donors as antioxidants occurs only by hydrogen transfer and upon contact of probe and quencher. To clarify this process experiments using spectroscopic methods were contributed to a detailed theoretical study of reaction pathways: "Fluorescence Quenching by Sequential Hydrogen, Electron, and Proton Transfer in the Proximity of a Conical Intersection", A. Sinicropi, R. Pogni, R. Basosi, M. A. Robb, G. Gramlich, W. M. Nau, M. Olivucci, Angew. Chem., Int. Ed. 2001, 40, 4185-4189 (Appendix). In summary, the result of this study was the design and synthesis of the new fluorescent membrane probe Fluorazophore-L that combines the unusual properties of DBO with a complete incorporation into model membranes. The properties of the new probe were assessed in monolayer and by fluorescence lifetime experiments. Its potency was proven by the interaction with natural antioxidants located in the proximity of membrane mimetic systems. These quenching experiments allowed a new insight into the processes involving antioxidants in microheterogeneous environments, especially an unusual inversion of the well-known reactivity pattern of ascorbic acid and the observation of the lateral diffusion of α-tocopherol along the surface of supramolecular assemblies

A preliminary assessment of water quality in fish cages on Lake Kariba, Zimbabwe

The water quality in fish cages on Lake Kariba was studied. The Kruskal-Wallis test was used to determine whether the water quality parameters differed significantly among the cage-types (cage-type effect). Secchi disc readings ranged from 2 to 4 metres, while temperature ranged from 23 degree C to 29.5 degree C. The observed conductivity was between 98.7 mu S/cm and 102.3 mu S/cm. The pH was between 6.31 and 7.82. Concentrations of dissolved oxygen varied from 1.55 to 6.47 mg/l, while dissolved oxygen saturation ranged from 22.3% to 83.1%. Within the same month, temperature did not differ significantly among cages. Conductivity, pH, dissolved oxygen concentration and dissolved oxygen saturation differed significantly among the 3 cage-types. Temperature and pH levels in the cages were close to the optimum levels for the culture of cichlids. Sub-optimal levels of dissolved oxygen occurred occasionally in the octagonal cages

Cell signaling promoting protein carbonylation does not cause sulfhydryl oxidation: implications to the mechanism of redox signaling

Reactive oxygen species (ROS) have been recognized as second messengers, however, targeting mechanisms for ROS in cell signaling have not been defined. While ROS oxidizing protein cysteine thiols has been the most popular proposed mechanism, our laboratory proposed that ligand/receptor-mediated cell signaling involves protein carbonylation. Peroxiredoxin-6 (Prx6) is one protein that is carbonylated at 10 min after the platelet-derived growth factor (PDGF) stimulation of human pulmonary artery smooth muscle cells. In the present study, the SulfoBiotics Protein Redox State Monitoring Kit Plus (Dojindo Molecular Technologies) was used to test if cysteine residues of Prx6 are oxidized in response to the PDGF stimulation. Human Prx6 has a molecular weight of 25 kDa and contains two cysteine residues. The Dojindo system adds the 15 kDa Protein-SHifter if these cysteine residues are reduced in the cells. Results showed that, in untreated cells, the Prx6 molecule predominantly exhibited the 55 kDa band, indicating that both cysteine residues are reduced in the cells. Treatment of cells with 1 mM H 2O 2 caused the disappearance of the 55 kDa band and the appearance of a 40 kDa band, suggesting that the high concentration of H 2O 2 oxidized one of the two cysteine residues in the Prx6 molecule. By contrast, PDGF stimulation had no effects on the thiol status of the Prx6 molecule. We concluded that protein carbonylation is a more sensitive target of ROS during ligand/receptor-mediated cell signaling than sulfhydryl oxidation

Summer Diapause of the Clover Leaf Weevil, \u3ci\u3eHypera Punctata,\u3c/i\u3e and Lesser Clover Leaf Weevil, \u3ci\u3eHypera Nigrirostris,\u3c/i\u3e in Wisconsin

Low respiration rates, immobility, lack of feeding, and undeveloped reproductive systems confirmed a summer diapause in the overwintered and current-year adults of the clover leaf weevil, Hypera punctata, and lesser clover leaf weevil, Hypera nigrirostris. The prolonged summer diapause and extended winters in Wisconsin set strict limitations on the available time for damaging populations to develop on red clover, Trifolium pratense thus assuring the status of these weevils as minor pests