Magnetic properties of the spin S=1/2S=1/2 Heisenberg chain with hexamer modulation of exchange

We consider the spin-1/2 Heisenberg chain with alternating spin exchange %on even and odd sites in the presence of additional modulation of exchange on odd bonds with period three. We study the ground state magnetic phase diagram of this hexamer spin chain in the limit of very strong antiferromagnetic (AF) exchange on odd bonds using the numerical Lanczos method and bosonization approach. In the limit of strong magnetic field commensurate with the dominating AF exchange, the model is mapped onto an effective $XXZ$ Heisenberg chain in the presence of uniform and spatially modulated fields, which is studied using the standard continuum-limit bosonization approach. In absence of additional hexamer modulation, the model undergoes a quantum phase transition from a gapped string order into the only one gapless L\"uttinger liquid (LL) phase by increasing the magnetic field. In the presence of hexamer modulation, two new gapped phases are identified in the ground state at magnetization equal to 1/3 and 2/3 of the saturation value. These phases reveal themselves also in magnetization curve as plateaus at corresponding values of magnetization. As the result, the magnetic phase diagram of the hexamer chain shows seven different quantum phases, four gapped and three gapless and the system is characterized by six critical fields which mark quantum phase transitions between the ordered gapped and the LL gapless phases.Comment: 21 pages, 5 figures, Journal of Physics: Condensed Matter, 24, 116002, (2012

Two-sex life table parameters of Mediterranean flour moth, Ephestia kuehniella (Zeller) (Lep.: Pyralidae) on different barley and wheat cultivars

In this study, two-sex life tableparameters of Ephestia kuehniella (Zeller) were studied on seven cultivars of barley (Dasht, Khorram, Sahra, Reihan03, Fajr30, 5shoor and EH-83-7) and two cultivars of wheat (Bam and Sepahan) at 25 ± 1 °C, 65 ± 5% R.H., and 16:8 (L: D) h. The shortest and the longest larval periods were recorded on Reihan03 (42.58 ± 0.69 days) and EH-83-7 (53.42 ± 0.95 days) cultivars respectively. The longest and the shortest developmental periods for E. kuehniella were found on EH-83-7 (72.12 ± 1.61 days) and on Sepahan (58.19 ± 1.00 days) cultivars respectively. The heaviest and lightest pupaewere observed on Sepahan (21.07 ± 0.77 mg) and Fajr30 (15.20 ± 0.58 mg) cultivars respectively. The intrinsic rate of increase and net reproductive rate were the highest (0.07 ± 0.00 day-1 and 87.41 ± 1.89 offspring, respectively) on Sepahan, and the lowest (0.037 ± 0.00 day-1 and 12.29 ± 0.48 offspring, respectively) on Dasht cultivars. The results indicate that Sepahan wheat cultivar is the most suitable cultivar for the laboratory rearing of E. kuehniella

Characterization of digestive α- and β-glucosidases in the midgut of Plagiodera versicolora Laicharting (Coleoptera: Chrysomelidae)

The imported willow leaf beetle, Plagiodera versicolora is one of the main pests of forest trees worldwide including Iran. Activities of α- and β-glucosidases in the midgut of P. versicolora adults were studied in this research. The results showed a higher α- glucosidase activity of adultsthan β-glucosidase. The optimal pHs for α- and β-glucosidases activities were found to be 6 and 9, respectively. Optimal temperatures for the enzymatic activities were recorded at 30 and 25 °C, respectively. Concentration of 0.5 mM K+ significantly minimized the activity of α- glucosidase and maximized the activity of α-glucosidase in presence of Ca2+. The activity of β-glucosidase was decreased by adding Mg2+ and Zn2+. 5 mM concentration of K+ had the most inhibitory impact on β-glucosidase activity, while 0.5 mM concentration of Na+ showed the most positive effect on the enzyme activity. The Km of midgut α- and β- glucosidase was 0.36 and 2.03 mM and the Vmax value was 5.46 and 18.51 μmol/min/mg protein, respectively

Some Physiological Effects of Nanofertilizers on Wheat-Aphid Interactions

The increasing use of nanofertilizers in modern agriculture and their impact on crop yield and pest management require further research. In this study, the effects of nano-Fe, -Zn, and -Cu (which are synthesized based on nanochelating technology), and urea (N) fertilizers on the antioxidant activities of wheat plants (cv. Chamran), and the wheat green aphid Schizaphis graminum (Rondani) are investigated. The authors observed the highest levels of phenolics in non-infested nano-Zn-treated plants (26% higher compared with control). The highest H2O2 levels are in the infested and non-infested nano-Zn-treated and infested nano-Fe-treated plants (in infested nano-Zn and nano-Fe treated plants, 18% and non-infested nano-Zn-treated plants, 28% higher compared with control). The highest peroxidase (POX) activity is observed in the infested and non-infested N-treated and non-infested water-treated plants (almost 14%, 37%, and 46% higher than control, respectively). The lowest activity is in the infested plants’ nano-Zn and -Fe treatments (almost 7 and 5 folds lower compared to the control, respectively). The highest and lowest catalase (CAT) activity are in the infested N-treated plants (almost 42% higher than control) and water-treated plants, respectively. The infested nano-Zn, -Fe, -Cu and Hoagland-treated plants showed the highest superoxide dismutase (SOD) activity. Regarding the antioxidant enzyme activities of S. graminum, the highest POX activity is in the nano-Cu treatment (more than two folds higher compared with control); the highest CAT and SOD activities are in the nano-Cu and -Zn treatments. It can be concluded that the application of nanofertilizers caused increasing effects on the wheat plant’s antioxidant system and its resistance to S. graminum

Nutritional indices of the Colorado potato beetle, Leptinotarsa decemlineata (Col.: Chrysomelidae) on six potato cultivars

سوسک کلرادوی سیب زمینی، Leptinotarsa decemlineata (Say)، یکی از آفات مهم سیب زمینی در ایران و جهان است. شاخص‌های تغذیه‌ای لارو‌های سن آخر این آفت روی برگ ارقام مختلف سیب زمینی (خاوران، ساوالان، لوتا، سانتا، سانته و آئولا) تحت شرایط آزمایشگاهی (دمای 1 ± ‌25 درجه سلسیوس، رطوبت نسبی 5‌ ± ‌65 در‌صد و دوره نوری 16 ساعت روشنایی و 8 ساعت تاریکی) بررسی شد. لاروهای پرورش‌یافته روی رقم سانته کم‌ترین کارایی تبدیل غذای خورده‌شده (07/1 ± 21/10 در‌صد) و هضم‌شده (08/1 ± 27/10 در‌صد) را داشتند. طبق نتایج به‌دست آمده، رقم سانته میزبان نامناسبی برای تغذیه این آفت بود

Comparison of some biological aspects of Empoasca decipiens (Hom.: Cicadellidae) on four bean species

Some biological aspects of Emposaca decipiens Paoli were investigated on different bean species (Phaseolus vulgaris L., P. lunatus L., P. calcaratus Roxb. and Vigna sinensis L.) under field and laboratory conditions (26 ± 1ºC, RH: 70 ± 5% and a photoperiod of 16L: 8D h.). The species of the host plant had no significant effect on incubation period, but the nymphal instars, development time, adult longevity and life span were affected by host plant species significantly. The shortest and longest development time in the field condition were occurred on V. sinensis (22.58 ± 0.50) and P. calcaratus (27.17 ± 0.67), respectively. But in laboratory conditions these parameters were observed on V. sinensis (20.71 ± 0.57) and P. vulgaris (29.29 ± 1.00), respectively. Adult longevity on V. sinensis had the longest duration. In contrast, the shortest adult longevity was observed on P. vulgaris. Surface of the leaves inV. sinensis is smooth and without trichomes, but presence of the hoocked trichomes on three other host plants especially in P. vulgaris assumed as the most important reason of their unsuitability for the leafhopper

Full-wave evaluation of a 40 dBi: Transmit-array for Ka-band SoTM

Transmit-array (TA) antennas have been shown to be a cost-effective solution for the new generation of satellite communications. These antennas are usually composed by thousands of fine-tuned subwavelength unit-cells. Therefore, full-wave evaluations become quite challenging as the required gain increases, constraining the antenna design and optimization. This is aggravated by the fact that, when beam scanning is required, higher gains cannot be obtained by simply scaling a given design. In fact, for a F/D ratio, the maximum gain of the TA is limited by the scanning aberrations. Recently, we have proposed a new phase compensation law for the TA, designated as the bifocal correction, that allows to overcome the usual gain/scanning tradeoff limit. However, due to the lack of computational resources, we were only able to demonstrate this concept for a 40 dBi TA using PO/GO methods. In this communication we present the full-wave performance of this 40 dBi bifocal TA design using a new efficient numerical evaluation method, properly validated with a smaller 30 dBi TA.info:eu-repo/semantics/acceptedVersio