Development of diffusive solid phase microextraction method for sampling of epichlorohydrin in air

Epichlorohydrin is used frequently in many industrial processes. Exposure to this pollutant could induce harmful effects. The present work developed a novel solid phase microextraction (SPME) method for time weighted average determination of epichlorohydrin in the air by GC/MS. CAR/PDMS in 0.5?cm retracted mode was selected and the effect of environmental parameters on sampling properties of SPME was examined. Experimental sampling rate for epichlorohydrin (8.89?×?10^?3?cm³/min) was slightly less than theoretical value (9.059?×?10^?3?cm³/min). There was no significant difference among sampling rates at different temperature and velocities but relative humidity had a significant effect on the sampling rate. Limit of detection for SPME method was 0.8?ng per sample, which is good enough in comparison with the NIOSH 1010 method. Comparison of the results between the developed SPME and the NIOSH 1010 method on standard test atmosphere and field showed satisfactory agreement (y?=?1.162x?+?1.8 r ²?=?0.992 and y?=?1.009x+0.76 r ²?=?0.98 respectively).     

A new AATP model with considering supply chain lead-times and resources and scheduling of the orders in flowshop production systems: A graph-theoretic view

The present study attempts to synchronize the scheduling problem with determining the advanced available-to-promise (AATP) in a flowshop system to enhance supplier profitability and service level. In the proposed model the AATP, scheduling and graph theory concept have been combined to find the optimum resource allocation and enable accurate estimations of machines scheduling, production costs and delivery dates. To find the near optimum solutions for the large size problems a genetic algorithm is developed, first the orders are ranked based on their scores which are estimated then the optimum cost is calculated by balancing profitability and constraints such as the availability of the machines or the available material in each workstation. Some computer simulated experiments are provided to evaluate the performance of the proposed algorithm.     

Characteristic assessment of stabilized polyacrylonitrile nanowebs for the production of activated carbon nano-sorbents

Polyacrylonitrile(PAN) nanofibers with average diameter of 300 nm were produced by electro-spinning. The nanofibers were stabilized at different temperatures in the range of 180-270 ℃ in several duration times and heating rates. Fourier transforms infrared(FTIR) spectroscopy, differential scanning calorimetry(DSC) and X-ray diffraction(XRD) analyzing techniques were employed to measure the extent of stabilization reaction. By all procedures, the ranges of temperature and duration time recommended were about 250-270 ℃ and 1-2 h, respectively. Increasing the activation temperature from 800 ℃ to 1200 ℃ caused porosity and pore volume development up to 60% and 0.532 cm3/g, respectively. Pore width of all samples was calculated to be about 0.7 nm confirming micro-pore structure of the produced PAN based activated carbon nanofibers. Comparing dye adsorption for different adsorbents including chitin and granular activated carbon(GAC) showed the highest efficiency for the produced activated carbon nanofibers(ACNFs).     

A sensitive opto-fluidic biosensor based on plasmonic-graphene/black phosphorous configuration for detection of hemoglobin concentrations

Optical Review - In this paper, a sensitive Opto-fluidic biosensor for detection of Hemoglobin concentrations in blood samples is proposed and considered. The proposed system is based on the...