Population density and spatial distribution pattern of Hypera postica (Coleoptera: Curculionidae) in Ardabil, Iran

The alfalfa weevil, Hypera postica (Gyllenhal), feeds almost exclusively on alfalfa, Medicago saliva L. in most region of the world where forage crop is grown. It has been investigated the population density and spatial distribution of alfalfa weevil on alfalfa in Ardabil during 2010. Using a 0.25 m(2) quadrate sample unit a reliable sample size was 65, with maximum relative variation of 15%. The relative variation (RV) of the primary sampling data was 13.6. The highest population density of the alfalfa weevil was recorded on 17(th) April. To estimate the spatial distribution pattern of this pest, data were analyzed through index of dispersion. Lloyd's mean crowding. Morisita's index and two regression models (Taylor's Power Law and Iwao's Patchiness Regression). Taylor's model showed an aggregated distribution pattern for all life stages. Iwao's patchiness regression indicated that larvae, adult and total life cycle had aggregated spatial distribution (t(c

Laboratory toxicity and field efficacy of Lufenuron, Dinotefuran and Thiamethoxam against Hypera postica (Gyllenhal, 1813) (Coleoptera: Curculionidae)

Toxicity of the insect growth regulator lufenuron and two neonicotinoids, dinotefuran and thiamethoxam, for the alfalfa weevil, Hypera postica (Gyllenhal, 1813), was determined through exposure of the second instar larvae and adults to dipped alfalfa leaves under laboratory conditions at 25±1 °C, 60±5% RH ,16:8 L:D. Based on mode of action, the mortality of the treated larvae and adults was recorded after 72 hours for lufenuron, and after 24 hours for dinotefuran and thiamethoxam. LC50 values for second instar larvae were 34.32, 24.91.32.9, 15.82 AI L-1 and for adults were 175.67, 289.76, 164.02 AI L-1 for dinotefuran, thiamethoxam and lufenuran, respectively. Results showed that lufenuron was the most toxic to both larvae and adults of H. postica among insecticides tested. Once the height of alfalfa field reached to about 20 cm, a single treatment was made on May 11th. All insecticides reduced the mean number of alfalfa weevil. According to results of laboratory and field experiments, lufenuron might be a more valuable chemical to adequately control H. postica with little adverse effects on environment. lufenuron may be considered as alternative chemicals to other compounds with a high potential for controlling certain pests and with less adverse effects on natural enemies

The trend of national and subnational burden of maternal conditions in Iran from 1990 to 2013: The study protocol

Background: It is widely accepted that maternal mortality is a proxy for maternal health status. Maternal deaths only represent the top of the iceberg; morbidity due to maternal causes apart from maternal mortality, poses a huge burden on women's families. There is an excessive need to widen the research on maternal morbidity. Here, we explain the framework of our study on maternal conditions and their burden in Iran as a part of the National and Sub-national Burden of Diseases (NASBOD) study. Methods: A systematic search will be carried out for both published and unpublished data on maternal mortality and morbidity reported between 1985 and 2013. Data collected through systematic review and those obtained from national and sub-national surveys will be extracted in a data set. Two statistical models will be applied: Bayesian Autoregressive Multi-level models and Spatio-Temporal Regression models. Models will be used to overcome the problem of data gaps across provinces, years and age groups. Discussion: In order to control and manage maternal conditions and to make more efficient and cost-effective policies, there is an excessive need for data on the burden of such diseases. There are a few sub-national analyses of the burden of disease. In the current study, burden of maternal conditions will be assessed at national and sub-national levels in Iran between 1990 and 2013. The results of this study are undoubtedly required to provide comprehensive information at the national and provincial levels to administer interventions more effectively, since the priority based policies need regional assessments and comparisons

Temperature effect on free vibration response of a smart multifunctional sandwich plate

A smart multifunctional sandwich plate with a wide range of applications can be produced by proper arrangement of its layers. This paper offers a smart multifunctional sandwich plate with one central lightweight porous layer, two middle polymer/graphene nanocomposite layers and two active faces made of a piezoceramic material. The coupled effects of temperature conditions and piezoelectric behavior on the natural frequencies of the proposed smart multifunctional sandwich plate located on elastic foundations have been studied in the current research. For the dispersions of graphene particles and pores inside host layers, different functional profiles have been considered. Moreover, graphene particles and polymeric materials with temperature-dependent material properties have been adopted. The mechanical properties of polymer/graphene nanocomposite are evaluated by employing Halpin-Tsai approach which is modified to capture nanoscale effects. Eventually, the coupled governing eigenvalue equations of the proposed smart multifunctional sandwich plate are derived using a third-order theory called TSDT and are studied by a developed meshless solution. In addition, the effects of graphene, porosity, geometric and foundation aspects on the natural frequency of the proposed smart multifunctional sandwich plate are studied. The results disclose that the natural frequencies of the proposed smart multifunctional sandwich plates are improved by embedding pores in core layer due to the remarkable reduction of structural weight. It is worth noting that nanocomposite layers can completely compensate the structural stiffness reduction caused by embedding pores in the core.The author(s) disclosed receipt of the following financial support for the research, author- ship, and/or publication of this article: The work described in this paper was supported by Natural Sciences and Engineering Research Council of Canada (NSERC under grant RGPIN-217525)

Electro-Mechanical Behavior of Smart Sandwich Plates With Porous Core and Graphene-Reinforced Nanocomposite Layers

The use of piezoelectric sensor and/or actuator layers in engineering structures provides smart sandwich structures with adaptive responses. Moreover, due to the brittle behavior of piezoceramic materials, inserting nanocomposite and porous layers between piezoelectric layers offers more flexible and lighter structures along with maintaining the advantages of nanocomposite materials. Therefore, in this paper, we have proposed smart sandwich plates consisting of a porous polymeric core and two graphene-reinforced composite (GRC) layers integrated with two piezoceramic layers. The distributions of porosities and randomly oriented graphene particles are assumed to be functionally graded (FG) along the thickness of core and nanocomposite layers, respectively. For the static behavior of the proposed sandwich plates, the coupled electro-mechanical governing equation has been extracted by minimizing potential energy equation with respect to displacement and electrical potential. The governing equation has been discretized by adopting a higher order shear deformation theory (HSDT) of plates and a developed mesh-free method. Using the developed solution framework, the effects of porosity and graphene characteristics, electromechanical loads, and layer thicknesses on the deflection behavior of the proposed FG piezoelectric porous nanocomposite sandwich plates (FG-PPNSPs) have been studied.The work described in this paper was supported by Natural Sciences and Engineering Research Council of Canada (NSERC under grant RGPIN-217525). The authors are grateful for their support

Electromechanical Natural Frequency Analysis of an Eco-Friendly Active Sandwich Plate

In conventional piezoelectric ceramics, their brittle nature and containing lead are two crucial issues that significantly restrict their uses in many applications such as biomedical devices. In this work, we suggest the use of an eco-friendly piezoelectric nanocomposite material to piezoelectrically activate a cantilever meta-structure plate to be used as a novel actuator/sensor or even energy harvester; this cantilever plate is formed of several polymeric links to create an auxetic core plate that structurally shows a negative Poisson’s ratio. Moreover, the active nanocomposite materials are used as the face sheets on the auxetic plate; these active layers are made of nanowires of zinc oxide (ZnO) that are placed into an epoxy matrix in different forms of functionally graded (FG) patterns. For such active sandwich plates (ASPs) with potential electromechanical applications, a coupled electromechanical analysis has been performed to numerically investigate their natural frequencies as a crucial design parameter in such electromechanical devices. By developing a meshless method based on a higher plate theory, the effects of nanowire volume fraction, nanowire distribution, auxetic parameters, layer dimensions, and electrical terminal set-up have been studied; this in-depth study reveals that ASPs with an auxetic core have much lower natural frequencies than ASPs with honeycomb cores which would be very helpful in designing actuators or energy harvesters using the proposed cantilever sandwich plates