Security toolbars in a web browser show security-related information about a website to help users detect phishing attacks. Because the toolbars are designed for humans to use, they should be evaluated for usability -that is, whether these toolbars really prevent users from being tricked into providing personal information. We conducted two user studies of three security toolbars and other browser security indicators and found them all ineffective at preventing phishing attacks. Even though subjects were asked to pay attention to the toolbar, many failed to look at it; others disregarded or explained away the toolbars' warnings if the content of web pages looked legitimate. We found that many subjects do not understand phishing attacks or realize how sophisticated such attacks can be.

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We report a one-step and environment-friendly synthesis of platinum nanoparticles with controlled shapes and sizes using wood nanomaterials in aqueous phase without employing any other reductants, capping or dispersing agents. This green process affords an easy route to the production of shape-selective metal nanoparticles. The obtained spherical and cubic Pt nanoparticles and spherical Pt nanoclusters exhibit high activities in the catalytic reduction of pnitrophenol as a model reaction.

Got a crush: Native cellulose can be dispersed as nanofibers in organic solvents by ball milling with esterification agents. Milling with hexanoyl chloride/DMF gives hexanoyl-coated nanofibers dispersible in several organic solvents. Milling with succinic anhydride/DMSO results water-dispersible nanofibers. The results open the way to new cellulose mechanochemistries.

The self-assembly and pH- and thermo-sensitivities properties of hydroxypropyl cellulose-graft-poly(N,N-dimethyl aminoethyl methacrylate) (HPC-g-PDMAEMA) copolymers in aqueous solutions were investigated by transmittance, dynamic light scattering (DLS), and (1)H NMR spectroscopy. Micelles with different structure can be formed by varying either pH value or temperature. At low pH, e.g., 3.0, the HPC backbone of the copolymer collapse to form the core of micelles stabilized with protonated PDMAEMA side chains on the surface of the micelles upon heating. At the medium pH, e.g., 8.1, both HPC backbone and PDMAEMA side chains collapse upon heating to form unstable aggregates. At high pH, e.g., 12.3, PDMAEMA side chains collapse first to form the core of micelles stabilized with HPC chains upon heating. Further heating the copolymer solution at this pH leads to the aggregation of the micelles due to the collapse of the shell HPC chains. The thermal sensitivity of the HPC-g-PDMAEMA copolymers is reversible.

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A green method was used to prepare cellulose nanocrystals (CNCs) with no use of harsh chemicals or organic solvents. This method was simple via ball milling cellulose with water followed by centrifugation. The diameter and length of the CNCs were 3–10 nm and 120–400 nm, separately, with a aspect ratio of 20–60. The yield was about 20%. The thermal stability of the CNCs was the same as that of raw cellulose owing to lacking of chemical modification. So it was superior to CNCs prepared by acid hydrolysis. Then poly­(vinyl alcohol) (PVA)/CNC composite film was made by solution casting. The results showed that the tensile strength of the composite film was 79% increased from neat PVA film when adding 5% CNCs to the PVA matrix. In addition, the composite films possessed good transparency and thermal stability.

The relationships between pH, dissolved oxygen (DO) and chlorophyll a in aquaculture and non-aquaculture waters are assessed in this paper. The research includes the evaluation of field and experimental studies at the Panjiakou Reservoir (between Aug and Oct 2009) and the review of international data covering two decades. The results indicated that typical eutrophic non-aquaculture water had mean concentrations of chlorophyll a of higher than 10 μg L −1 , and significant positive correlations were found between pH, DO and chlorophyll a. When the mean concentration of chlorophyll a was less than 10 μg L −1 , no correlation was found between DO and chlorophyll a for waters with a high exchange rate or heavily organically polluted natural waters. Diurnal variations were found for both pH and DO. A corresponding significant positive correlation was found between both water quality parameters. In general, when the mean concentration of chlorophyll a was less than 10 μg L −1 within aquaculture waters of low exchange rate, only a weak or no correlation at all was found between pH, DO and chlorophyll a during summer and autumn. On the other hand, a significant positive correlation between pH and chlorophyll a and a significant positive correlation or no correlation between DO and chlorophyll a were found for aquaculture waters with a high exchange rate during summer and autumn. Strong diurnal variations for both pH and DO were identified. A significant positive linear correlation between pH and DO was found for field enclosure experiments.