Surface functionalization of silver nanoparticles: novel applications for insect vector control

Every day, people and animals contract debilitating and life threatening diseases due to bites from infected flies, ticks, and mosquitoes. The current methods utilized to fight against these diseases are only partially effective or safe for humans and animals. When it comes to insect vector control, a conceptual paradigm shift is urgently needed. This work proposes a novel synthetic scheme to produce a nanoparticle-pesticide core-shell conjugate to be used as an active agent against arthropod vectors, such as mosquitoes. As a proof of concept, we conjugated nanosilver to the pyrethroid pesticide deltamethrin. First, electron microscopy and Fourier transform infrared spectroscopy verified the presence of a 15 nm nanosilver core surrounded by deltamethrin. Second, when the conjugate was exposed to mosquitoes for a 24 h bioassay, mortality was observed at 9 × 10(-4) M. Silver was detected in the hemolymph of mosquitoes exposed to the conjugate. We concluded that the newly developed nanoconjugate did not inactivate the primary function of the pesticide and was effective in killing mosquitoes at low concentrations. These results demonstrate the potential to use nanoparticle surfaces to kill insects, specifically vectors of human pathogens.     

Molecular dynamics study of nano mass transfer in a vibrating cantilevered carbon-nanotube

We investigate the nano mass transfer in an ultrahigh frequency carbon-nanotube-resonator encapsulating a nanocluster via classical molecular dynamics simulations. When the carbon-nanotube-resonator vibrated, the encapsulated copper nanocluster more rapidly approached the end of the cantilevered carbon-nanotube-resonator. Such phenomena were due to the migration of the encapsulated copper nanocluster due to the centrifugal force induced by the vibrating nanotube resonator. So the resonance frequency change could be time-dependently found. For the movable copper nanocluster in carbon nanotube resonator, the vibrational spectra when the copper nanocluster inside the carbon nanotube resonator rapidly settled at the capped edge were different from those obtained when the copper nanocluster continuously oscillated inside the carbon nanotube resonator. Such results showed that the frequency of the carbon-nanotube-resonator encapsulating the movable copper nanocluster could be adjusted by controlling the mean position of the oscillating copper nanocluster. The movable nanocluster inside a carbon-nanotube can be applied to a nanotube-based data storage media by sensing the position of the nanocluster.     

Synthesis and characterization of 3-[131I]iodo-L-tyrosine grafted Fe3O4@SiO2 nanocomposite for single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI)

In this study, we have successfully developed 3-[131I]iodo-tyrosine grafted Fe3O4@SiO2 nanocomposites for dual potential tumor imaging agent for SPECT and MRI. Fe3O4 nanoparticle was synthesized through thermal decomposition and Fe3O4@SiO2 was prepared by reverse microemulsion method. After conjugating aminopropyltriethoxysiliane, L-tyrosine was introduced by amide coupling reaction. Finally, [131I]iodide was labeled on L-tyrosine grafted Fe3O4@SiO2 nanocomposite by aromatic iodination using chloramine-T.     

Synthesis and properties of siloxane-containing hybrid hydrogels with alpha,omega-functionalized macromers

Siloxane-containing transparent hybrid hydrogels, coupled with high oxygen permeability and moderate equilibrium water content (EWC), were successfully obtained through free radical bulk copolymerization of hydrophobic and hydrophilic monomers. Due to obvious incompatibility of hydrophobic tris(trimethylsiloxy)-3-methacrryloxypropylsilane (TRIS) and hydrophilic 2-hydroxyehtyl methacrylate (HEMA) or N-vinyl pyrrolidone (NVP) monomers, alpha,omega-methacrylate terminated poly(dimethyl siloxane) (PDMS) macromer was employed as a compatibilizer in the formulations, resulting in high optical transmittance (> 90% at 400 nm) of the hybrid hydrogels. Although properties such as EWC and oxygen permeability of the hybrid hydrogels could be tailored over a wide range, the formulations with the PDMS macromer could not increase both EWC and oxygen permeability of the hybrid hydrogels without sacrificing one of them. For controlling these two properties simultaneously, an amphiphilic alpha,omega-methacrylate terminated PEO-PDMS-PEO triblock copolymer was synthesized as a surface-active macromer, and showed its usefulness in controlling phase separation and improving oxygen permeability and EWC, at the same time, of the hybrid hydrogels.     

Shape-dependent cytotoxicity of polyaniline nanomaterials in human fibroblast cells

The toxicity of polyaniline (PANI) nanomaterials with four different aspect ratios on human lung fibroblast cells was investigated by cell viability assay, cytotoxicity assay, apoptosis/necrosis measurement, and reactive oxygen species production. The toxicity increased with decreasing aspect ratio of PANI nanomaterials. In contrast, the highest aspect ratio PANI nanomaterials showed similar results with bulk PANI materials. The adverse effect of PANI nanomaterials was also concentration- and time-dependent. Low aspect ratio PANI nanomaterials induced more necrosis and more reactive oxygen species than others. These results provide new understanding of shape-dependent toxicity of nanomaterials.     

Reproducing polynomial particle methods for boundary integral equations

Since meshless methods have been introduced to alleviate the difficulties arising in conventional finite element method, many papers on applications of meshless methods to boundary element method have been published. However, most of these papers use moving least squares approximation functions that have difficulties in prescribing essential boundary conditions. Recently, in order to strengthen the effectiveness of meshless methods, Oh et al. developed meshfree reproducing polynomial particle (RPP) shape functions, patchwise RPP and reproducing singularity particle (RSP) shape functions with use of flat-top partition of unity. All of these approximation functions satisfy the Kronecker delta property. In this paper, we report that meshfree RPP shape functions, patchwise RPP shape functions, and patchwise RSP shape functions effectively handle boundary integral equations with (or without) domain singularities.     

NDC1: a nuclear periphery component required for yeast spindle pole body duplication

The spindle pole body (SPB) of Saccharomyces cerevisiae serves as the centrosome in this organism, undergoing duplication early in the cell cycle to generate the two poles of the mitotic spindle. The conditional lethal mutation ndc1-1 has previously been shown to cause asymmetric segregation, wherein all the chromosomes go to one pole of the mitotic spindle (Thomas, J. H., and D. Botstein. 1986. Cell. 44:65-76). Examination by electron microscopy of mutant cells subjected to the nonpermissive temperature reveals a defect in SPB duplication. Although duplication is seen to occur, the nascent SPB fails to undergo insertion into the nuclear envelope. The parental SPB remains functional, organizing a monopolar spindle to which all the chromosomes are presumably attached. Order-of-function experiments reveal that the NDC1 function is required in G1 after alpha-factor arrest but before the arrest caused by cdc34. Molecular analysis shows that the NDC1 gene is essential and that it encodes a 656 amino acid protein (74 kD) with six or seven putative transmembrane domains. This evidence for membrane association is further supported by immunofluorescent localization of the NDC1 product to the vicinity of the nuclear envelope. These findings suggest that the NDC1 protein acts within the nuclear envelope to mediate insertion of the nascent SPB.     

Life stress and dysphoria: The role of self-esteem and hopelessness.

Evaluated the hypotheses that the relation between life stress (life events and daily hassles) and longitudinal change in dysphoria would be (1) moderated by self-esteem and (2) mediated by longitudinal change in hopelessness. 80 undergraduates were first assessed on self-esteem, hopelessness, and dysphoria and then reassessed 3 mo later on life events, daily hassles, hopelessness, and dysphoria. Residual change in dysphoria was significantly associated with self-esteem, life stress, and a self-esteem?×?life stress interaction. However, inconsonant with predictions, the moderating impact of self-esteem was greatest under conditions of low (vs high) life stress. Moreover, residual change in hopelessness mediated the relations between residual change in dysphoria and both self-esteem and life stress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanism of Infrared Detection and Transduction by Beetle Melanophila Acuminata In memory of Jerry Wolken

The Melanophila acuminata beetle is attracted to forest fires via a pair of infrared sensory organs composed of sensilla. Our histological work showed that each sensillum contains lipid layers surrounding a protein layer and a unique polysaccharide base that is associated with a neuron to each sensillum. Infrared microscopy showed that the protein region maximally absorbs infrared radiation at 3 μm wavelength and at 10 μm, which corresponds to the known radiation produced by forest fires at 3 μm.Mathematical calculations showed that the physical properties of the sensilla are such that the expected temperature rise is insufficient for transduction of the infrared signal through mechanical means or as a thermal receptor as previously thought;hence the protein plays the pivotal role in perception of single photons and transmission of the signal within the sensilla.