Allelochemicals fromPilocarpus goudotianus leaves

The effect on germination, shoot, and root growth by bergapten, xanthotoxin, imperatorin, xanthyletin, xanthoxyletin, luvangetin, donatin and alloxanthoxyletol fromPilocarpus goudotianus leaves, onLactuca sativa var. nigra seedlings has been evaluated. A structure-activity correlation is discussed based on the bioassay results. Furanocoumarins appear to be the most active compounds in comparison with pyrano- and simple coumarins. The presence of an oxygenated function at C-8 decreases the germination effect in furano- and pyranocoumarins, while C-5 substituents do not cause significant changes on the activity.Part 2 in the series:Natural Product Models as Allelochemicals. For Part 1 see: Macíaset al. (1992).     

Hydrogen adsorption characteristics of magnesium combustion derived graphene at 77 and 293 K

Bulk graphene was prepared by the method of magnesium combustion in a CO₂ atmosphere, producing large quantities of material which had a different morphology and importantly, a more ordered carbon lattice than reduced graphene oxide and other bulk graphene synthetic methodologies. Despite a low surface area of 235.5 m²/g and ca 9 at.% of magnesium and its oxides which do not contribute to hydrogen adsorption, we observe 0.85 wt.% of H₂ at 65 bar and 77 K, and 0.9 wt.% of H₂ at 300 bar and 293 K. As this methodology readily produces many-gram quantities with cheap starting materials, we anticipate that with further enhancements to the synthetic methodology, improving both surface area and reducing reaction by-products, this material will provide a robust platform for further H₂ adsorption investigations.     

Collaboratively envisioning the future of community psychology in Canada: From talk to action.

Community Psychology (CP) is a relatively young and marginalized discipline in Canada, with only four graduate programs, concentrated in two provinces–Ontario and Québec. Recognising the need to develop cohesion and an identity as a field, several senior Canadian community psychologists proposed hosting a biennial conference, which began in 2002 at the University of Ottawa. Starting in 2006, the conference became a forum for CP faculty, students, and community partners to collaboratively develop a vision for the future of CP in Canada. Diverse teams of conference participants were engaged in facilitated discussions, culminating in a plenary session in which delegates shared their perspectives with the larger group. Eight themes emerged from the visioning exercises in 2006, which led to the development of special interest groups in the following areas: developing a sense of identity; clarifying and defining the field of CP; raising the profile of CP in Canada; promoting a CP education across Canada; enhancing recognition, credibility, and accreditation; establishing links within the field of psychology; building interdisciplinary bridges; international and diverse perspectives; and promoting healthy communities through grassroots social action. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Allocating surveillance effort in the management of invasive species: A spatially-explicit model

Invasive organisms often exist at low densities at the beginning and end of eradication programs. As a consequence, such organisms are often difficult to find, particularly if they are dispersed long distances to unknown locations. In such circumstances, large amounts of money can be spent searching for invasive organisms without finding any. However, chance encounters between invasive organisms and private citizens can occur even when invasive organisms exist at low densities. Reports of these ‘passive detections’ may be a critically important source of information for public pest management agencies. Rates of reporting may be improved using bounty payments and increasing public awareness about the presence of the invader. To explore the importance of passive surveillance in general, and its interaction with active surveillance by pest management agencies, we developed a simulation model of the spread of an invasive species. Simulations conducted under alternative scenarios for detection rates and search effort applied demonstrate that even small increases in detection or reporting rates substantially reduced eradication costs and increased the probability of eradication. In circumstances where resources are insufficient to achieve eradication, the simulation model provides useful information on the minimum expenditure required to contain the invasion.     

A study on the cutting force and chip shrinkage coefficient in high-speed milling of A6061 aluminum alloy

In this paper, finite element (FE) simulation for high-speed milling of aluminum alloy was performed using a ductile fracture model with Mohr–Coulomb criterion proposed by Bai and Wierzbicki (BW). To verify the model, predicted cutting forces were compared to experimental results in the same cutting conditions. Then, further simulations were performed to estimate the cutting forces and chip shrinkage coefficients subjected to different cutting parameters such as cutting speeds, cutting depths, and clearance angles of a cutting tool. The obtained results were also used to determine optimal cutting parameters using the Taguchi method. The analysis of variance (ANOVA) was employed to investigate the influence percentage of each cutting parameter on cutting force and chip shrinkage coefficient. The simulation results showed that inclusion of strain rate in numerical model significantly improved the accuracy of estimated cutting force in comparison to experiment. The optimum values obtained for high-milling process were cutting speed 1000 m/min, cutting depth 1 mm, clearance angle 15°, and rake angle 4°.     

Differential Proteomic Analysis of the Pancreas of Diabetic db/db Mice Reveals the Proteins Involved in the Development of Complications of Diabetes Mellitus

Type 2 diabetes mellitus is characterized by hyperglycemia and insulin-resistance. Diabetes results from pancreatic inability to secrete the insulin needed to overcome this resistance. We analyzed the protein profile from the pancreas of ten-week old diabetic db/db and wild type mice through proteomics. Pancreatic proteins were separated in two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and significant changes in db/db mice respect to wild type mice were observed in 27 proteins. Twenty five proteins were identified by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) and their interactions were analyzed using search tool for the retrieval of interacting genes/proteins (STRING) and database for annotation, visualization and integrated discovery (DAVID). Some of these proteins were Pancreatic α-amylase, Cytochrome b5, Lithostathine-1, Lithostathine-2, Chymotrypsinogen B, Peroxiredoxin-4, Aspartyl aminopeptidase, Endoplasmin, and others, which are involved in the metabolism of carbohydrates and proteins, as well as in oxidative stress, and inflammation. Remarkably, these are mostly endoplasmic reticulum proteins related to peptidase activity, i.e., they are involved in proteolysis, glucose catabolism and in the tumor necrosis factor-mediated signaling pathway. These results suggest mechanisms for insulin resistance, and the chronic inflammatory state observed in diabetes.     

Effect of sucrose and saturated-fat diets on mRNA levels of genes limiting muscle fatty acid and glucose supply in rats

In this study, we examined whether the increased availability of lipids in blood resulting from two types of diet manipulation regulated metabolic gene expression in the skeletal muscle of rats. Feeding for 4 wk on an isocaloric-sucrose or a hypercaloric-fat diet increased plasma TAG in the fed condition by increments of 70 and 40%, respectively, and increased fasting insulinemia (approximately 3-fold) compared with a starch diet. The fat diet impaired glucose tolerance and caused obesity, whereas sucrose-fed rats maintained their normal weight. We analyzed the expression of genes that regulate the exogenous FA supply (LPL, FAT/CD36, FATP1), synthesis (ACC1), glucose (GLUT4, GLUT1, HK2, GRAT1, glycogen phosphorylase) or glycerol (glycerol kinase) provision, or substrate choice for oxidation (PDK4) in gastrocnemius and soleus muscles at the end of the glucose tolerance test. LPL, FAT/CD36, FATP1, PDK4, and GLUT4 mRNA as well as glycogen phosphorylase and glycerol kinase activity levels in both muscles were unchanged by the diets. Increased mRNA levels of GLUT1 (1.6- and 2.6-fold, respectively) and GFAT1 (about 1.7-fold) in gastrocnemius, and of ACC1 (about 1.5-fold) in soleus, were found in both the sucrose and fat groups. In the fat group, HK2 mRNA was also higher (1.8-fold) in the gastrocnemius. Both sucrose and saturated-fat diets prompted hyperinsulinemia and hyperlipemia in rats. These metabolic disturbances did not alter the expression of LPL, FAT/CD36, FATP1, PDK4, and GLUT4 genes or glycogen phosphorylase and glycerol kinase activity levels in either analyzed muscle. Instead, they were linked to the coordinated upregulation in gastrocnemius of genes that govern glucose uptake and the hexosamine pathway, namely, GLUT1 and GFAT1, which might contribute to insulin resistance.     

Local-instantaneous filtering in the integral transform solution of nonlinear diffusion problems

A novel filtering strategy is proposed to be utilized in conjunction with the Generalized Integral Transform Technique (GITT), in the solution of nonlinear diffusion problems. The aim is to optimize convergence enhancement, yielding computationally efficient eigenfunction expansions. The proposed filters include space and time dependence, extracted from linearized versions of the original partial differential system. The scheme automatically updates the filter along the time integration march, as the required truncation orders for the user requested accuracy begin to exceed a prescribed maximum system size. A fully nonlinear heat conduction example is selected to illustrate the computational performance of the filtering strategy, against the classical single-filter solution behavior.     

Formation of calcium alginate gel capsules: influence of sodium alginate and CaCl2 concentration on gelation kinetics

The formation kinetics of calcium alginate gel capsules is studied. An increase in the concentration of alginate gives rise to a reduction in membrane thickness, while an increase in the concentration of calcium chloride leads to the formation of a thicker film. Experimental data are adjusted to the binomial diffusion equation.     

Morphological features of the crystalline or quasicrystalline silicides observed in the quaternary Al-Fe-Mo-Si alloys

Rapidly solidified Al-Fe-Mo-Si powders were produced by centrifugal atomization and then consolidated by hot extrusion. Five compositions were chosen in order to obtain a theoretical constant volume fraction of (silicide + Al₁₂Mo) of 20%, with different relative fractions of [silicide]/[-matrix] and different ratios of [Fe]/[Mo] within the silicide. This paper presents the microstructures observed in both as-atomized and consolidated states. The only phase detected by X-Ray Diffraction, the non equilibrium ternary Al_12-13(Fe,Mo)₃Si, exhibits different sizes and morphologies and is inhomogeneously distributed within the matrix. Accurate electron microscopy observations indicate that this silicide may grow from a quasicrystalline precursor. Grains within the polycrystalline silicide often exhibit orientation relationships (micro twinning) giving rise to quasicrystalline-like patterns.