Buprofezin dissipation and safety assessment in open field cabbage and cauliflower using GC/ITMS employing an analyte protectant

An analytical method for the determination of buprofezin residues in cabbage and cauliflower was developed and validated using gas chromatography with ion trap mass spectrometry. The analyte protectant d ‐sorbitol was used at a concentration level of 0.5 mg mL^?1 in acetonitrile instead of in matrix for constructing the calibration curves of the buprofezin standard. The average recoveries ranged from 91.3 to 96.8%, with an RSD of ≤2.7%. The limits of detection and quantitation of the method in cabbage and cauliflower were 1.3, 1.7 and 4.3, 6.2 μg kg^?1, respectively. The residual levels and dissipation kinetics of buprofezin 25% wettabe powder in cabbage and cauliflower cultivated under open field conditions was investigated at the single (T1) and double (T2) recommended rates of application. Half‐life periods were found to be 1.73 and 2.1 days in cabbage, whereas in cauliflower, these values were 1.85 and 2.36 days at T1 and T2, respectively. Based on the dissipation study, and the maximum residue limit value of 0.05 mg kg^?1, the proposed pre‐harvest interval of buprofezin in cabbage was 3–6 days and that in cauliflower was 4–10 days. The results showed that buprofezin is safe for application at both recommended application rates.     

Impact of Offloading on the Efficiency of Wireless Access Networks

International Journal of Wireless Information Networks - Wireless access networks need to deliver a satisfactory level of Quality of Service (QoS) to their subscribers. The service quality can be...     

Effects of Microstructural Defects on Ion-Irradiated Type-316 Stainless Steel

Microstructure defects play a very important role in the swelling of irradiated stainless steel. This work is a parametric study of the effects of microstructural defects on the swelling of ion-irradiated steel. For simplicity, vacancy loop effects were neglected. Cold working was found to play a complicated role in the swelling behavior. On one hand, it increase the bias to interstitial absorption due to the increase in dislocation density. On the other hand, it decreases the total flux of point defects to voids by the decrease of the point defect concentrations. Grain size has also a strong effect on swelling. It was found that large gain sizes produces higher swelling and vise versa, i.e. the larger the surface of grain boundaries the less the irradiation-produced swelling. Similar effects were found for precipitates.     

Synthesis of tetracyclic and pentacyclic phenothiazines via benzotriazole methodology

Treatment of 10-(benzotriazol-1-yl)alkylphenothiazine with electron-rich alkenes in the presence of zinc bromide gave tetracyclic phenothiazines 4 and 9 as well as pentacyclic phenothiazines 5 , which have potential use in the pharmaceutical industry.     

Ion Beam Mixing for Silicide Formation

Refractory metal silcides are under intensive investigation to be used as contact and interconnect materials in VLSI circuits. Ion beam mixing has been proposed as a technique for simultaneous doping and metal silicide formution. This work presents a theoretical model for calculating the different parameters required for ion beam mixing through ion implantation. The minimum ion beam energy and dose for complete mixing is calculated. A plot of the obtained energy-dose relation shows that the dose increases linearly with energy. The dose-silicide thickness relation is also plotted. It is found that the thickness of the formed metal silicide increases linearly with the square root of the applied dose. A good agreement is found between the values and relations of the proposed model and experimental results.     

Performance Comparison of Single-Stage Three-Level Resonant AC/DC Converter Topologies

In this paper, the performance of different three-level resonant converters is studied for single-stage power factor correction operation. These converters are suitable for power ranges higher than that in the currently available single-stage converters, due to their high efficiency and reduced component stresses. All the converters presented here are characterized by their ability to regulate the output voltage as well as the dc bus voltage. This leads to lower voltage stresses, wider input voltage range, higher output power applications, and improved efficiencies compared to existing single-stage topologies. Due to the availability of more degrees of freedom in the presented converters, two types of control strategies can be used for this purpose: variable frequency asymmetrical pulsewidth modulation control and variable frequency phase-shift modulation control. Three resonant converters will be studied in this paper and their performances as well as the applicability of the aforementioned control methods for each converter are compared. A 2.3-kW, 48-V converter with input voltage range of 90-265 V_rms is used to study the performance of each case.     

Energy spectra and charge fractions for keV hydrogen and helium backscattered from silicon

Energy spectra and charge fractions for hydrogen and helium backscattered from silicon targets are reported. The primary energy of the incident particle varies from 5 to 15 keV. The backscattered energy distributions are measured down to 500 eV and the results are compared to a Monte-Carlo computer simulation. Good agreement is found between the theoretical model and the experimental data. Charge fractions are measured by differentiating between scattered ions and neutrals. For hydrogen, neutralization occurs primarily at the surface for the backscattered particles and no depth effects are found. Helium shows a large peak in the ion yield for surface scattering with a much reduced ion yield for particles scattered from within the solid.     

Enaminones as building blocks in heterocyclic synthesis: New syntheses of nicotinic acid and thienopyridine derivatives

Reacting 1,3‐diphenyl‐propan‐2‐one with equimolecular amount of dimethylformamide dimethylacetal afforded the enaminone 4. This when reacted with another equimolecular amount of dimethylformamide dimethylacetal afforded the dienaminone 5. Compound 4 condenses with cyanothioacetamide and with cyanoacetamide to yield 2‐thioxo‐ and 2‐oxo‐pyridine‐3‐carbonitrile derivatives 6a,b respectively. Compound 6a reacted with α‐chloroacetone 8 to yield the thieno[2,3‐b]pyridine derivative 10 that cyclized further into 4,7,8‐trisubstituted pyrido[2′,3′:2,3] thieno[4,5‐d]pyrimidine 12. Compound 4 also afforded 2,5,6‐trisubstituted nicotinic acid ethyl ester 13 by reaction with ethyl acetoacetate in acetic acid in the presence of ammonium acetate. The dienaminone 5 reacted with acetic acid, ammonium acetate/acetic acid, phenylhydrazine and 5‐amino‐3‐methylpyrazole yielding 3,5‐diphenyl‐pyran‐4‐one 15a , 3,5‐diphenyl‐1H‐pyridin‐4‐one 15b and 1,3,5‐trisubstituted pyridin‐4‐ones 16a‐b.