Facile synthesis of graphene oxide-silver nanocomposite for decontamination of water from multiple pollutants by adsorption, catalysis and antibacterial activity.

Here in, we presented a facile one-step method for the synthesis of Graphene oxide-silver (GO-Ag) nanocomposite and its applications as a sorbent for the elimination of some toxic pollutants from aqueous medium, as an efficient catalyst in the individual as well as simultaneous reduction reactions of multiple compounds, and as an antibacterial agent for the destruction of some harmful microorganisms existent in wastewater. GO was prepared using a modified Hummers method and Ag nanoparticles were integrated on GO sheets by chemical reduction of Ag+ ions on the surfaces of GO sheets. The composition and morphology of the nanocomposite was extensively characterized with elemental dispersive X-ray analysis (EDX), Fourier transform infra-red (FT-IR) spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). The GO-Ag nanocomposite demonstrated remarkable adsorption capacities and recyclability for malachite green (MG) and ethyl violet (EV) dyes. Various experimental parameters affecting adsorptive behavior of nanocomposite like temperature, pH, time of contact between dye and adsorbent, and adsorbent dose were evaluated thoroughly. Experimental data was simulated with different adsorption isotherms and kinetic models to evaluate adsorption behavior of both dyes and results confirmed the adsorption of both the dyes to be followed by pseudo 2nd order kinetic model and Langmuir adsorption model. Moreover, adsorbent was regenerated in suitable media for both dyes without any loss in removal efficiency. The catalytic performance for the 2-nitroaniline (2-NA) reduction was investigated in detail. Most importantly, the prepared nanocomposite was found to have potential to adsorb multiple pollutants all together as well as to catalyze the simultaneous reduction of a mixture of dyes (MG, MO, and EV) and 2-NA. An additional advantage of the GO-Ag nanocomposite was its antibacterial activity acquired to the presence of Ag nanoparticles. Two bacterial strains (Gram-negative bacterium, E. coli and the Gram-positive bacterium, S. aureus) were used to test antibacterial activity of composite and the results confirmed the remarkable performance of the nanocomposite in destroying harmful pathogens.

Gross Dissection Time Values of Pathologists' Assistants Using Standardized Metrics.

OBJECTIVES: A validated and objective method to quantify the gross dissection time of pathologists' assistants (PAs) does not exist. We propose a method to calculate standardized work units (dissection time values [DTVs]) to monitor PA productivity. METHODS: The Current Procedural Terminology system specifies six levels of specimen complexity encompassing 176 unique specimen types. Using our institutional dictionary, we designated all specimen types into a priori five levels of complexity based on expected dissection time. We hypothesized that expected time could be matched prospectively with the actual measured dissection time for all specimens. Dissection time data were collected prospectively for 12,775 specimens at two tertiary academic medical centers, and work effort was converted to a numeric DTV equivalent (number of minutes to dissect single specimen/420 minutes in a working day). RESULTS: For 44 of 155 specimen types, measured dissection time for the five "levels" was lower than expected dissection (P < .0001). Accordingly, those 44 specimen types were reclassified to a lower level. CONCLUSIONS: A numeric standard of the work effort for dissection time for 155 specimen types was developed, validated, and then used prospectively to monitor grossing efficiency of PA workforce.