Exploration of density functional methods for one‐electron reduction potential of nitrobenzenes

Performance of the set of density functional approaches for calculation of one‐electron reduction potentials of nitroaromatic compounds was investigated. To select the most precise and affordable method, we selected a set of model molecules and investigated effects of basis set, density functional, and solvation model on the calculation of reduction potentials. It was found that the mPWB1K/TZVP method provides the most accurate gas phase electron affinity values (RMS error is 0.1 eV). This method in conjunction with the PCM (Bondi) method yields also the most accurate difference in solvation energies of neutral oxidized form and anion‐radical reduced form. The final E⁰ values were calculated with RMS error of 0.10 V, compared with experimental values. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010     

Effects of Different Doses of Low Power Continuous Wave He–Ne Laser Radiation on Some Seed Thermodynamic and Germination Parameters,and Potential Enzymes Involved in Seed Germination of Sunflower (Helianthus annuus L.)

In this study, water-soaked seeds of sunflower were exposed to He–Ne laser irradiation of different energies to determine whether or not He–Ne laser irradiation caused changes to seed thermodynamic and germination parameters as well as effects on the activities of germination enzymes. The experiment comprised four energy levels: 0 (control), 100, 300 and 500 mJ of laser energy and each treatment replicated four times arranged in a completely randomized design. The experimentation was performed under the greenhouse conditions in the net-house of the Department of Botany, University of Agriculture, Faisalabad. The seed thermodynamic parameters were calculated according to seed germination thermograms determined with a calorimeter at 25.8°C for 72 h. Various thermodynamic parameters of seed (ΔH, (ΔS)_e, (ΔS)_c, (ΔS)_e/Δt and (ΔS)_c/Δt) were affected significantly due to presowing laser treatment. Significant changes in seed germination parameters and enzyme activities were observed in seeds treated with He–Ne laser. The He–Ne laser seed treatment resulted in increased activities of amylase and protease. These results indicate that the low power continuous wave He–Ne laser light seed treatment has considerable biological effects on seed metabolism. This seed treatment technique can be potentially employed to enhance agricultural productivity.     

Br...O contacts and π–π stacking dominate the packing in methyl 4‐bromo‐3,5‐dimethoxybenzoate

The title compound, C₁₀H₁₁BrO₄, a useful precursor to pharmaceutically active isocoumarin and isochroman derivatives, crystallizes with two unique molecules in the asymmetric unit. A π–π stacking interaction links the planar molecules in the asymmetric unit. Additional π–π contacts stack pairs of molecules along the c axis. A feature of the crystal packing is the presence of a number of short Br...O contacts. A particularly unusual arrangement involves the formation of dimers, with pairs of Br...O contacts imposing a close Br...Br interaction and generating five‐membered rings within an eight‐membered ring formed by two Br...O contacts. Only two comparable arrangements have been reported previously. The Br...O contacts combine with weak C—H...O hydrogen bonds to form corrugated sheets of molecules approximately parallel to (001). These sheets are stacked along the c axis by π–π interactions to generate a three‐dimensional network.     

Molecular evolution of rice S 5 n and functional comparison among different sequences

The wide compatibility gene, S ₅ ⁿ , can overcome embryo sac sterility between indica and japonica subspecies of rice. Therefore, it is very important to characterize the features of the S ₅ ⁿ sequence to reveal the origin and evolution of S ₅ ⁿ . In this paper, 26 cultivated rice haplotypes and 22 wild rice accessions harboring S ₅ ⁿ were used to sequence S ₅ ⁿ . The results showed that 15 genotypes among the 48 materials were fully consistent with control cultivar 02428 (CK). The other 33 accessions had different degrees of variation in the S ₅ ⁿ sequence. Variations in the coding region mainly occurred in the second exon and eight materials showed a 10-bp deletion at 1710?C1719 bp, including wild (O. nivara) and cultivated rice, such as IRW501 and Yuetai B. S ₅ ⁿ sequences were not biased and evolved neutrally. The 48 materials could be divided into 4 categories using a phylogenetic tree of the amino acid sequences. Most of the wild rice clustered together, and the cultivated rice clustered into another group. Eight cultivated rice and O. nivara (wild rice) clustered in another group, which were found to lack 10 consecutive bases in exon 2. Eight rice varieties with high numbers of differences in their S ₅ ⁿ coding regions were crossed with testers (typically indica and japonica) to produced test cross F₁ populations. The F₁s were examined for their ability to overcome indica-japonica hybrid sterility. The result showed that the embryo sac fertility of S ₅ ⁿ -containing hybrids increased significantly compared with control hybrids, but there were no differences among the materials with divergent sequences, indirectly proving that S ₅ ⁿ is a non-functional gene.     

Expert judgment based multi-criteria decision model to address uncertainties in risk assessment of nanotechnology-enabled food products

Currently, risk assessment of nanotechnology-enabled food products is considered difficult due to the large number of uncertainties involved. We developed an approach which could address some of the main uncertainties through the use of expert judgment. Our approach employs a multi-criteria decision model, based on probabilistic inversion that enables capturing experts’ preferences in regard to safety of nanotechnology-enabled food products, and identifying their opinions in regard to the significance of key criteria that are important in determining the safety of such products. An advantage of these sample-based techniques is that they provide out-of-sample validation and therefore a robust scientific basis. This validation in turn adds predictive power to the model developed. We achieved out-of-sample validation in two ways: (1) a portion of the expert preference data was excluded from the model’s fitting and was then predicted by the model fitted on the remaining rankings and (2) a (partially) different set of experts generated new scenarios, using the same criteria employed in the model, and ranked them; their ranks were compared with ranks predicted by the model. The degree of validation in each method was less than perfect but reasonably substantial. The validated model we applied captured and modelled experts’ preferences regarding safety of hypothetical nanotechnology-enabled food products. It appears therefore that such an approach can provide a promising route to explore further for assessing the risk of nanotechnology-enabled food products.     

Detection reagents used for on-plate identification of organic pesticides in biological samples with preliminary separation by TLC/HPTLC

Many specific and non-specific chromogenic spray reagents have been used to detect organic pesticides (organophosphorus, organochlorine, carbamates, and pyrethroids) on thin-layer chromatographic (TLC)/high-performance thin-layer chromatographic (HPTLC) plates. To realize high sensitivity and improved selectivity, several chromogenic reagents have been introduced. The physical properties of organic pesticides reported so far are also presented in tabular form. The colors produced on TLC plates due to reactions taking place between pesticides and spray reagents are illustrated in the form of chromatograms, and reaction mechanism is also presented.

     

Applications of thin-layer chromatography and thin-layer electrophoresis in the analysis of inorganic anions: a review

JPC – Journal of Planar Chromatography – Modern TLC - This review is intended to highlight various applications of thin-layer chromatography (TLC) and thin-layer electrophoresis (TLE)...     

Response of Aphid Parasitoids to Volatile Organic Compounds from Undamaged and Infested Brassica oleracea with Myzus persicae

Headspace solid microextraction (HS-SPME) and GC-MS were used to investigate volatile organic compounds (VOCs) from cabbage plants infested and uninfested with green peach aphid Myzus persicae. The HS-SPME combined with GC-MS analysis of the volatiles described the differences between the infested and uninfested cabbage. Overall, 28 compounds were detected in infested and uninfested cabbage. Some VOCs released from infested cabbage were greater than uninfested plants and increased the quantity of the composition from infested plants. According to the peak area from the GC-MS analysis, the VOCs from infested cabbage consisted of propane, 2-methoxy, alpha- and beta pinene, myrcene, 1-hexanone, 5-methyl-1-phenyl-, limonene, decane, gamma-terpinen and heptane, 2,4,4-trimethyl. All these volatiles were higher in the infested cabbage compared with their peak area in the uninfested cabbage. The results of the study using a Y-shape olfactometer revealed that the VOCs produced by infested cabbage attracted Myzus persicae substantially more than uninfested plants or clean air. The percentage of aphid choice was 80% in favor of infested cabbage; 7% were attracted to the clean air choice and uninfested plants. A total of aphids 7% were attracted to clean air. Comparing between infested and uninfested cabbage plants, the aphid was attracted to 63% of the infested cabbage, versus 57% of the uninfested cabbage. The preferences of Aphidus colemani and Aphelinus abdominalis to the infested or uninfested plants with M. persicae and compared with clean air indicated that parasitoids could discriminate the infested cabbage. Both parasitoids significantly responded to the plant odor and were attracted to 86.6% of the infested cabbage plants.     

Development and applications of deep eutectic solvents in different chromatographic techniques

JPC – Journal of Planar Chromatography – Modern TLC - Deep eutectic solvents (DESs) being inexpensive, easy to prepare, biocompatible, biodegradable and environmentally benign have...     

Superconductivity in (Cu0.5Tl0.25Li0.25)Ba2Ca2Cu3−ySiyO10−δ samples

The (Cu_0.5Tl_0.25Li_0.25)Ba₂Ca₂Cu_3?ySi_yO_10?δ (y = 0, 0.25 0.5, 0.75, 1.0, 1.25) superconductor samples have been prepared by solid-state reaction method. The critical temperature and as well as the magnitude of diamagnetism is increased up to Si concentration y = 1.0, however, from the doping level y = 1.25 a decrease in the critical temperature along with the vanishing of the diamagnetism was observed. The carrier’s in the conducting CuO₂/SiO₂ planes were optimized by carrying out post-annealing in oxygen and an increase in the critical temperature was observed in all Si doped samples. The doping efficiency of Cu_0.5Tl_0.5Ba₂O_4?δ charge reservoir layer in (Cu_0.5Tl_0.25Li_0.25)Ba₂Ca₂Cu_3?ySi_yO_10?δ (y = 0, 0.25 0.5, 0.75, 1.0, 1.25) samples is enhanced by doping Li⁺¹ ion; as alkali metals are known to easily loose their outer most electron which could be supplied to CuO₂/SiO₂ conducting planes and would suppress the anti-ferromagnetism in the inner conducting planes. The FTIR absorption measurements have provided an indirect evidence of Si substitution at in CuO₂ planes.