Feeding deterrency of some pyrrolizidine,indolizidine, and quinolizidine alkaloids towards pea aphid (Acyrthosiphon pisum) and evidence for phloem transport of indolizidine alkaloid swainsonine

Journal of Chemical Ecology - The feeding deterrency of a series of pyrrolizidine, indolizidine, and quinolizidine alkaloids and selected derivatives was measured against the pea aphid...     

Gaming Social Capital: Exploring Civic Value in Multiplayer Video Games

Recent research suggests that social interactions in video games may lead to the development of community bonding and prosocial attitudes. Building on this line of research, a national survey of U.S. adults finds that gamers who develop ties with a community of fellow gamers possess gaming social capital, a new gaming‐related community construct that is shown to be a positive antecedent in predicting both face‐to‐face social capital and civic participation.     

Ruthenium supported on new TiO2–ZrO2 systems as catalysts for the partial oxidation of methane

The partial oxidation of methane is studied at 673–873 K over new Ru-based catalysts supported on TiO₂–ZrO₂ with different TiO₂ content. Supports were prepared by a sol–gel method, and RuCl₃ and RuNO(NO₃)₃ were used as ruthenium precursors to prepare the catalysts (1–2 wt% Ru). The effect of the reaction temperature on the catalytic behavior is analyzed, along with the support composition and the Ru precursor used.     

The effects of calystegines isolated from edible fruits and vegetables on mammalian liver glycosidases

The polyhydroxylated nortropane alkaloids called calystegines occur in many plants of the Convolvulaceae, Solanaceae, and Moraceae families. Certain of these alkaloids exhibit potent inhibitory activities against glycosidases and the recently demonstrated occurrence of calystegines in the leaves, skins, and sprouts of potatoes (Solanum tuberosum), and in the leaves of the eggplant (S. melongena), has raised concerns regarding the safety of these vegetables in the human diet. We have surveyed the occurrence of calystegines in edible fruits and vegetables of the families Convolvulaceae, Solanaceae, and Moraceae by GC-MS. Calystegines A3, B1, B2, and C1 were detected in all the edible fruits and vegetables tested; sweet and chili peppers, potatoes, eggplants, tomatoes, Physalis fruits, sweet potatoes, and mulberries. Calystegines B1 and C1 were potent competitive inhibitors of the bovine, human, and rat beta-glucosidase activities, with Ki values of 150, 10, and 1.9 microM, respectively for B1 and 15, 1.5, and 1 microM, respectively, for C1. Calystegine B2 was a strong competitive inhibitor of the alpha-galactosidase activity in all the livers. Human beta-xylosidase was inhibited by all four nortropanes, with calystegine C1 having a Ki of 0.13 microM. Calystegines A3 and B2 selectively inhibited the rat liver beta-glucosidase activity. The potent inhibition of mammalian beta-glucosidase and alpha-galactosidase activities in vitro raises the possibility of toxicity in humans consuming large amounts of plants that contain these compounds.     

Successful drug treatment of schistosomal myelopathy. A case report

In a patient who presented with quadriplegia a large mass was demonstrated radiologically in the cervical part of the spinal canal. The patient came from an area where there is a high prevalence of schistosomiasis, and antischistosomal antibodies were present in the serum. Treatment with the antischistosomal drug niridazole led to a total clinical recovery and almost complete disappearance of the myelographic filling defect.     

Infant parasite rates and immunoglobulin M seroprevalence as a measure of exposure to Plasmodium falciparum during a randomized controlled trial of insecticide-treated bed nets on the Kenyan coast

Repeated cross-sectional surveys among infants sleeping under insecticide-treated bed nets (ITBN) and contemporary control infants were used to estimate changes in Plasmodium falciparum exposure due to ITBN use on the Kenyan coast. Presence of P. falciparum parasites or total P. falciparum Immunoglobulin M (IgM) seropositivity were used independently and in combination in a constant risk catalytic conversion model to estimate the force of infection in ITBN and control communities. Such studies during infancy avoid problems of early saturation of prevalence due to high forces of infection and persistence of infection, minimize problems of self-treatment, and can be conducted among large populations covering a wide geographic area. These contrast previous parasitologic studies of ITBN among older children and the traditional entomologic studies of transmission that are logistically demanding. Our investigations demonstrated that parasite prevalence, IgM seropositivity, and the force of transmission were all significantly reduced by 50%. In addition, more infants under ITBN entered their second year of life without previous exposure to P. falciparum than control infants. These effects upon delayed acquisition of effective immunity require careful monitoring during future vector control programs using ITBN.     

Thermodynamics of noncovalent interactions in hydrophobically‐substituted water‐soluble polymers from intrinsic viscosity measurements: Application to nucleobase‐substituted pullulans

Hydrophobically substituted water‐soluble polymers (HSWSP) act as associative thickeners through the reversible crosslinking from noncovalent interactions between the various groups on the polymer chains in aqueous solution. This article shows how the intrinsic viscosity (IV) of nonionic HSWSP can be used to define the thermodynamics of these interactions. Literature data on the IV of pullulans substituted by nucleobase ester groups (thyminylbutyryl and adeninylbutyryl) (Mocanu et al., Can J Chem, 1995, 73, 1933) are used as an exemplar of these procedures. The intramolecular crosslinking in these substituted pullulans is deduced to be “unimolecular” (association constant K₁ = 1 M^?1), as contrasted with the “bimolecular” behavior expected from the stacking of the free nucleobases; evidently the crosslinking results from hydrophobic interactions between the butyryl linking groups and the main chain. The results are compared with those from other HSWSP, and from cosolute binding systems. The use of the water–octanol partition coefficients of model systems to elucidate hydrophobic interactions in HSWSP, and of denaturant cosolutes (especially urea) to diagnose the presence and strength of these interactions, are also discussed. Emphasis is placed on the need for further such studies to identify the interactions underlying the rheological behavior of the nonionic HSWSP, and of the more common ionic types. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Corrosion,erosion-corrosion,and the flexural strength of WC-Co hardmetals

The corrosion of commercial hardmetals containing 6, 8 and 10% Co with small additions of Cr₃C₂ and VC, in solutions of pH 1, 3, 5 and 10, and in a cutting fluid of pH 8.6, has been investigated using weight loss, atomic absorption spectroscopy, and metallographic techniques. For a surface area 420 mm², at 20°C, the amount of cobalt dissolved in pH 5 and 10 solutions was less than 0.05 mg per day and in the cutting fluid was less than 0.05 mg in 7 days. Salt in the water increased the corrosion rate in the pH 10 solution by over five times. Corrosion was highest in the hardmetal containing VC. Corrosion in a pH 1 solution at 20 °C for 24 h (weight loss about 1 mg) did not affect the mean strength of the hardmetals. Erosion by alumina balls during corrosion increased the corrosion rate in the pH 1 solution by 16 to 29 times, formed a thick layer of WC denuded of cobalt, and reduced the strength of the eroded-corroded hardmetals by 0.54 to 0.76 times.     

How the Problem of Consciousness Could Emerge in Robots

I show how a robot with what looks like a hard problem of consciousness might emerge from the earnest attempt to make a robot that is smart and self-reflective. This problem arises independently of any assumption to the effect that the robot is conscious, but deserves to be thought of as related to the human problem in virtue of the fact that (1) the problem is one the robot encounters when it tries to naturalistically reduce its own subjective states (2) it seems incredibly difficult from the robot??s own naturalist perspective and, most importantly, (3) it invites the robot to engage in the exact same metaphysical responses as humans offer to the problem of consciousness. Despite the fact that it invites the robot to consider extravagant metaphysical solutions, the problem I explore is purely algorithmic. The robot cannot complete its naturalist physicalist reduction as a matter of algorithmic fact, whether or not the naturalist physicalist reduction would be correct as a matter of metaphysical fact. It is hoped that by reproducing the familiar seeming problem in an artificial context, a greater understanding of the human problem of consciousness can be achieved.