Does excretion of secondary metabolites always involve a measurable metabolic cost? Fate of plant antifeedant salicin in common brushtail possum, Trichosurus vulpecula

Salicin was administered orally to six brushtail possums by incorporation in food for six days at three dose levels (0.05, 0.5, and 1.5% wet weight), giving mean ± SD daily intakes of 0.31 ± 0.09, 2.76 ± 0.75, and 6.04 ± 1.12 mmol salicin. Metabolites were identified by mass spectrometry and assayed by HPLC. Salicyl alcohol glucuronide accounted for 56–64% of urinary metabolites over the three doses, salicyluric acid 15–26%, salicin 10–18%, and there were smaller amounts of free (2–4%) and conjugated (0–6%) salicylic acid. ,2-Dihydroxyphenylpropionic acid was a minor metabolite. The hydrolysis of dietary salicin enabled reconjugation of its aglycone, salicyl alcohol, with a more polar sugar, glucuronic acid, thus enhancing its renal excretion and resulting in little net loss of substrates for conjugation and a low measurable metabolic cost of excretion.     

Electronic and steric effects in gold(i) phosphine thiolate complexes

The unusual yellow color of Au(2)(dppm)(SR)(2) (R = 4-tolyl; dppm = diphenylphosphinomethane) is attributed to a red-shift in the S-->Au charge transfer caused by destabilization of the sulfur highest occupied molecular orbital (HOMO). Variable temperature experiments show two broad bands at -80 degrees C in the (31)P{(1)H} NMR spectrum of Au(2)(dppm)(SR)(2) and the activation energy for interconversion is 10 kcal/mol. Only one sharp band is observed down to -80 degrees C in the spectrum of the white complex, Au(2)(dppe)(SR)(2) (dppe = diphenylphosphinoethane). Molecular mechanics calculations on Au(2)(dppm)(SR)(2) and Au(2)(dppe)(SR)(2) reveal that, for Au(2)(dppe)(SR)(2), a series of maxima and minima, separated by 2.5 kcal/mol, occur every 120 degrees which is consistent with rotation around an unhindered carbon-phosphorus single bond. The Au atoms are not within bonding distance in any conformation. Computational results for Au(2)(dppm)(SR)(2) indicate one minimum energy structure in which the Au-P bonds are anti. There is a high energy conformation (9 kcal/mol above the global minimum) where overlap between golds is maximized. The implications of gold-gold bonding in this complex are discussed. The steric influence of the thiolate ligand has been examined by synthesizing a series of dinuclear gold(I) complexes in which the steric properties of the thiolate are varied: Au(2)(dppm)(SR)(2) (R = 2,6-dichlorophenyl; 2,6-dimethylphenyl; 3,5-dimethylphenyl). The 2,6-disubstituted complexes are white, while the 3,5-dimethyl complex is yellow. These results, along with VT-NMR experiments, are consistent with the conclusion that the more sterically-bulky thiolates hinder the close approach of the golds in the dinuclear complexes.     

The Effects of Substrate Bias and Edge Proximity on the Mechanical Properties and Machining Performance of TiN-Coated Carbide Inserts

The effects of substrate bias on magnetron sputter-deposited TiN-coated carbide inserts were examined with a focus on the property changes that occur near the cutting tool edge. Sandvik SPG-422 polished carbide inserts were coated with TiN using substrate bias levels ranging from ?25 to ?150 V. The hardness was measured using the nano-indentation method and x-ray diffraction was used to measure residual stress. The bias strongly affected the appearance of the region 1-2 mm from the tool edge with defect formation, cracking, and delamination observed at the higher substrate bias levels. For samples deposited at bias levels of up to ?50 V, the coating composition was not strongly affected by edge proximity and the hardness exhibited only a small increase with bias of about 3 GPa. The residual stresses were measured using the sin²ψ method, and it was found that both the increasing bias level and proximity to the edge increased the degree of compressive stress, reaching ?3.2 GPa at edge location of the ?50 V bias sample. The machining performance was assessed by turning hardened 4340 steel, and only the samples deposited at ?25 and ?35 V exhibited substantial improved tool wear in comparison to an uncoated edge. These results correlated well with the appearance of the cutting tool edge and the measured stress levels.     

Mineral and trace element composition of the Lokpanta oil shales in the Lower Benue Trough, Nigeria

The concentrations of minerals and trace elements in the Lokpanta oil shale from the Lower Benue Trough, Nigeria have been determined by X-ray diffraction (XRD) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), respectively. X-ray diffraction data were evaluated using the SIROQUANT™ interactive data processing system based on Rietveld interpretation methods. A new method of trace element determination in oil shale, involving LA-ICP-MS analysis of glass beads prepared by fusing oil shale ash on an iridium strip heater was used, and the accuracy of the method was assessed by including a standard shale reference material (SGR-1b) in the analysis program.The minerals in the raw oil shales are mainly quartz, calcite and clay minerals, with the latter being represented by kaolinite and interstratified illite/smectite. Ashes of the oil shale samples prepared at 815 °C have quartz and (in some cases) illite as the dominant mineral phases, along with a significant proportion of amorphous materials. The Lokpanta oil shales are highly enriched in some potentially hazardous trace elements, including V, Cr and Ni, when compared with oil shales from other deposits around the world. The results obtained for the trace elements in the reference material show that the LA-ICP-MS method described in this study is very accurate and precise for the determination of a wide range of trace elements in oil shales.     

Synthesis of a tritopic,third-generation bis(1-pyrazolyl)methane ligand and its silver(I) complex: Unexpected structure with high coordination numbers

The reaction of the new tritopic ligand C₆H₃[CH₂OCH₂CH(pz)₂]₃ (L_tri, pz = pyrazolyl ring), prepared to determine the types of complex architectures its metal complexes will form, with Ag(O₃SCF₃) yields {[AgL_tri](O₃SCF₃)}_n. The solid-state structure of this complex is a two-dimensional sheet in which each of the three bis(pyrazolyl)methane units coordinate three different symmetry equivalent Ag(I) cations, with each Ag(I) bonding to three different ligands. Because of a significant disorder in one “arm” of the ligand, approximately half of the Ag(I) cations are six-coordinate and the other half are five-coordinate. In the six-coordinate case, the Ag(I) is in a trigonal prismatic geometry and in the five-coordinate case the disordered bis(pyrazolyl)methane unit is in an unusual κ¹-coordination mode. These structural types are very different from those observed with analogous multitopic poly(pyrazolyl)methane ligands, where cages and mononuclear metallacycles are observed.     

University students' notebook computer use: lessons learned using e-diaries to report musculoskeletal discomfort

The objective of this pilot study was to identify if notebook accessories (ergonomic chair, desktop monitor and notebook riser) combined with a wireless keyboard, mouse and participatory ergonomics training would have the greatest impact on reducing self-reported upper extremity musculoskeletal discomfort in university students. In addition to pre-post computing and health surveys, the Ecological Momentary Assessment was used to capture change in discomfort over time using a personal digital assistant (PDA) as the e-diary. The PDA was programmed with a survey containing 45 questions. Four groups of university students were randomised to either intervention (three external computer accessories) or to control. Participants reported less discomfort with the ergonomic chair and notebook riser based on the pre-post survey data and the e-diary/PDA ANOVA analysis. However, the PDA data, adjusted for the effect of hours per day of computer use, showed no benefit of the chair and limited benefit from the riser. Statement of Relevance:University students' use of notebook computers has increased. This study found evidence of a positive effect of an adjustable chair or notebook riser when combined with ergonomic training on reducing discomfort. Daily notebook computer use of 4?h was confirmed as a risk factor. Without some form of ergonomic intervention, these students are likely to enter the workforce with poor computing habits, which places them on the road to future injuries as technology continues to play a dominant role in their lives.     

Food Cent$--implementing and evaluating a nutrition education project focusing on value for money

The photophysics and polarization of the phosphorescence and delayed fluorescence of erythrosin in conditions compatible with the current biological applications of the dye (aqueous buffers at pH 7.4 at ambient temperatures) and in ethanol have been studied as a function of dye concentration (10(-7)-10(-5) M) and temperature (245-333 K). The emission decay is strictly single exponential and the detailed kinetic analysis of all the rate processes connected with the emitting T1 state showed that (1) the lowering of the emission lifetime at the higher temperatures is due to a very efficient self-quenching process, (2) the back intersystem crossing rate T1-->S1 is temperature dependent (delta ETS approximately 7 kcal mol-1) but the T1-->S0 is not (Ea < 0.1 kcal mol-1) and (3) both intersystem crossing processes are very sensitive to solvent polarity, which accounts for the solvent dependence of the phosphorescence yield and lifetime. The high value of the phosphorescence anisotropy (r0 = 0.25 +/- 0.006) is independent of the excitation and emission wavelengths, and its evolution in time accurately reflects the rotational restrictions in solid solutions. The relevance of these findings to studies with protein-dye conjugates is also outlined to facilitate the design and interpretation of phosphorescence depolarization experiments that probe the microsecond-ms dynamics of biomolecules and supramolecular systems.     

Role of TGF-beta in RA-induced cleft palate in CD-1 mice

Retinoic acid (RA) plays an important role in embryogenesis, by regulating morphogenesis, cell proliferation, differentiation, and extracellular matrix production. RA exposure on gestational day (GD) 12 in CD-1 mice results in delayed palatal shelf elevation and subsequent clefts in the secondary palate. Given the dynamic and complex nature of palate development, it is not surprising that this system is susceptible to changes in retinoid levels. There is evidence that experimental manipulation of retinoid status during development alters normal transforming growth factor-beta (TGF-beta) status. To study the role of perturbation in TGF-beta levels in RA-induced cleft palate, gravid CD-1 mice were treated with 70 mg/kg RA on GD 12. We examined changes in TGF-beta proteins and the steady-state level of TGF-beta mRNA within the first 24 hr after exposure. The interactions between RA and TGF-beta s were very complex. RA differentially regulated the mRNA and protein levels of TGF-beta 1. Changes in mRNA steady-state levels were rapid and transient in nature, indicating a direct mediation by RA. Differential regulation was evident, because RA treatment resulted in an increase in TGF-beta 1 mRNA steady levels followed by a decrease in the intracellular and extracellular forms of TGF-beta 1 protein. Moreover, the patterns of localization and levels of TGF-beta 2 and TGF-beta 3 proteins were not dramatically affected, although there was an increase in TGF-beta 3 mRNA steady-state levels. The increases in mRNA steady-state levels for TGF-beta 2 and TGF-beta 3, as for TGF-beta 1, were rapid and transient in nature, again arguing for direct mediation by RA. These data provide evidence for interactions between RA and TGF-beta s, and indicate that RA is capable of differentially regulating TGF-beta isoforms through processes involving different stages of TGF-beta synthesis and secretion. Further, changes in TGF-beta isoforms were observed prior to changes in mesenchyme morphology and must be considered as mediators of RA's effects on mesenchyme development.