Variations of growth rate of Eucalyptus delegatensis R. T. Baker seedlings at five elevations

Eucalyptus delegatensis R.T. Baker, from a single seed source, was grown at five sites over a range of elevations from 260 m to 600 m on two soil types, in the Surrey Hills district of North West Tasmania. Seedlings were harvested twice, after 26 and 74 weeks of growth. Dry weight and leaf area were measured and at the second harvest the net assimilation rate was calculated for each elevation. The seedlings at the five elevations formed three significantly different populations, as discriminated on the basis of dry weight and leaf area. The differences in NAR can best be explained by variation in the length of the growing season, and the severity and duration of frosts over the altitudinal range. The population with the highest NAR (4.16gm sq dm -1 week-I) was grown below 300 m, in an area where Eucalyptus obliqua is the dominant wetsclerophyll forest species. The population with medium NAR (2.03 gm sq dm-1 week-1 ) was grown at three sites between 300 and 600 m, in an area where E. delegatensis wet sclerophyll forest is the -1 major vegetation type. The poor growth of the third population (NAR = 0.72 gm sq dm week - ), grown above 600 m, corresponds to an area in which E. delegatensis grassy woodlands, and Nothofagus cunninghamii rainforest are the predominant vegetation types

The phytochemical, antibacterial and antioxidant activity of five medicinal plants against the wound infecting bacteria

Leaf extracts of Senna italica, Ricinus communis, Lantana camara, Lippia javanica and Ziziphus  mucronata were screened for biological activity against bacteria which infect wounds. The leaves were extracted using different solvents of varying polarity (hexane, dichloromethane, acetone and methanol). Phytochemical analyses of the extracts were performed using thin layer chromatography (TLC). The extracts were loaded on TLC plates and developed in three solvent systems that is benzene/ethanol /ammonium solution (BEA), chloroform/ethyl acetate/formic acid (CEF) and ethyl acetate/methanol /water (EMW). Antibacterial activity of the plants was evaluated using micro-dilution and bioautography methods. The test organisms used were Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis. Acetone extracts were chosen for antioxidant activity. Methanol was the best extractant, followed by acetone and dichloromethane (DCM). In the phytochemical analysis,  more compounds were observed on BEA, followed by EMW and CEF plates. Lantana camara had no  activity against any of the bacteria used. P. aeruginosa was the most resistant bacterium with only two plants active against it. E. faecalis and E. coli were sensitive to the extracts. More antibacterial  compounds were observed on BEA plates against all the test bacteria in bioautographic method. The Rf  values calculated from bioautography indicated that the selected plants have different active compounds. The most active compounds were from S. italica and Z. mucronata. BEA and EMW plates had good  antioxidant activity. No antioxidant activity was observed on the CEF plate. Most extracts were active against wound pathogens; their application on the wound area may prevent infection. Further studies are required to identify the active compounds in the plant extracts which showed significant anti-bacterial activities.Key words: Thin layer chromatography (TLC), plant extract, bacteria

Direct observation of delithiation as the origin of analog memristance in LixNbO2

The discovery of analog LixNbO2 memristors revealed a promising new memristive mechanism wherein the diffusion of Li+ rather than O2- ions enables precise control of the resistive states. However, directly correlating lithium concentration with changes to the electronic structure in active layers remains a challenge and is required to truly understand the underlying physics. Chemically delithiated single crystals of LiNbO2 present a model system for correlating lithium variation with spectroscopic signatures from operando soft x-ray spectroscopy studies of device active layers. Using electronic structure modeling of the x-ray spectroscopy of LixNbO2 single crystals, we demonstrate that the intrinsic memristive behavior in LixNbO2 active layers results from field-induced degenerate p-type doping. We show that electrical operation of LixNbO2-based memristors is viable even at marginal Li deficiency and that the analog memristive switching occurs well before the system is fully metallic. This study serves as a benchmark for material synthesis and characterization of future LixNbO2-based memristor devices and suggests that valence change switching is a scalable alternative that circumvents the electroforming typically required for filamentary-based memristors

Spacers to improve performance and porosity of graphene based polymer electrolyte fuel cells

Graphene has been suggested as a potential support material to replace commercial carbon black due to its carbon corrosion resistance. However, graphene-based electrodes typically perform poorly in MEA testing due to restacking of the graphitic sheets. In this study we investigate the introduction of carbon black and their effects on the porosity and current density of graphene-based supports

No Random, No Ransom: A Key to Stop Cryptographic Ransomware

To be effective, ransomware has to implement strong encryption, and strong encryption in turn requires a good source of random numbers. Without access to true randomness, ransomware relies on the pseudo random number generators that modern Operating Systems make available to applications. With this insight, we propose a strategy to mitigate ransomware attacks that considers pseudo random number generator functions as critical resources, controls accesses on their APIs and stops unauthorized applications that call them. Our strategy, tested against 524 active real-world ransomware samples, stops 94% of them, including WannaCry, Locky, CryptoLocker and CryptoWall. Remarkably, it also nullifies NotPetya, the latest offspring of the family which so far has eluded all defenses

Direct-to-consumer genetic testing: where and how does genetic counseling fit?

Direct-to-consumer genetic testing for disease ranges from well-validated diagnostic and predictive tests to ‘research’ results conferring increased risks. While being targeted at public curious about their health, they are also marketed for use in reproductive decision-making or management of disease. By virtue of being ‘direct-to-consumer’ much of this testing bypasses traditional healthcare systems. We argue that direct-to-consumer genetic testing companies should make genetic counseling available, pre- as well as post-test. While we do not advocate that mandatory genetic counseling should gate-keep access to direct-to-consumer genetic testing, if the testing process has the potential to cause psychological distress, then companies have a responsibility to provide support and should not rely on traditional healthcare systems to pick up the pieces