Toxicity of spray and fumigant products containing cassia oil to Dermatophagoides farinae and Dermatophagoides pteronyssinus (Acari: Pyroglyphidae)     

Kim SI  Kim HK  Koh YY  Clark JM  Ahn YJ 《Pest management science》2006,62(8):768-774

The toxicity of formulations of oil of cassia, Cinnamomum cassia Blume, (20 and 50 g L(-1) sprays and 100% oil-based fumigant) to adult Dermatophagoides farinae Hughes and D. pteronyssinus Trouessart was examined using contact and vapour-phase toxicity bioassays. Results were compared with the lethal activity of three commercial acaricides: benzyl benzoate, dibutyl phthalate and diethyl-m-toluamide (deet). The contact toxicity of cassia oil to both dust mite species was comparable with that of benzyl benzoate but was higher than that of the other two acaricides. Sprays containing 20 and 50 g L(-1) cassia oil were effective against both mite species when applied to fabric, glass, paper, plastic, tin or wood substrates. Applications of the 50 g L(-1) spray to different space volumes and surface areas determined that 50-60 mg of cassia oil was needed to control dust mites in 3.4 m(3) or in 1 m(2). In tests with fumigant devices, toxicity varied according to the thickness of non-woven fabric covering the device, the exposure time, the number of fumigant devices used and the volume of the space sprayed. Fumigant toxicity to adult D. pteronyssinus was more pronounced with devices enclosed in thinner (40 microm) versus thicker (45 or 50 microm) non-woven fabric covers. A single fumigant device with a 40 microm thick non-woven fabric cover resulted in substantial control in a space of 0.05 m(3) but exhibited only moderate to weak control in spaces >or= 0.097 m(3) at 4 days after application. Two fumigant devices gave 88% mortality in a space of 1.73 m(3). Cassia oil applied as sprays or in fumigant devices appears to provide effective protection of humans from house dust mites.  相似文献   

Changes in chemical and physical properties of yellow poplar (Liriodendron tulipifera) during torrefaction     

Byeong-Il Na  Byoung-Jun Ahn  Jae-Won Lee 《Wood Science and Technology》2015,49(2):257-272

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Information storage and retrieval through quantum phase     

Ahn J  Weinacht TC  Bucksbaum PH 《Science (New York, N.Y.)》2000,287(5452):463-465

Information was stored as quantum phase in an N-state Rydberg atom data register. One or more flipped states stored in an eight-state atomic wave packet could be retrieved in a single operation, in agreement with a recent proposal by Grover.  相似文献   

Activation tagging of the floral inducer FT   总被引：5，自引：0，他引：5  

Kardailsky I  Shukla VK  Ahn JH  Dagenais N  Christensen SK  Nguyen JT  Chory J  Harrison MJ  Weigel D 《Science (New York, N.Y.)》1999,286(5446):1962-1965

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Hematite nanospheres of possible colloidal origin from a precambrian banded iron formation   总被引：1，自引：0，他引：1  

Ahn JH  Buseck PR 《Science (New York, N.Y.)》1990,250(4977):111-113

Exceptionally small spheres (nanospheres) of hematite (diameters between 120 and 200 nanometers) occur in the Marra Mamba Iron Formation of the Hamersley Basin, Australia. The nanospheres are clustered into small aggregates and may have formed by structural ordering and dehydration of colloidal iron hydroxide particles. Individual spheres consist of numerous thin, curved hematite platelets surrounding a central void that is approximately half the diamter of the sphere; this texture suggests that they formed by a volume reduction of the original colloidal particles by approximately 12.5%. The occurrence of hematite nanospheres supports the hypothesis that some ofthe iron was deposited colloidally during the development ofbanded iron formations, approximately 2.5 billion years ago.  相似文献   

Architecture of a charge-transfer state regulating light harvesting in a plant antenna protein     

Ahn TK  Avenson TJ  Ballottari M  Cheng YC  Niyogi KK  Bassi R  Fleming GR 《Science (New York, N.Y.)》2008,320(5877):794-797

Energy-dependent quenching of excess absorbed light energy (qE) is a vital mechanism for regulating photosynthetic light harvesting in higher plants. All of the physiological characteristics of qE have been positively correlated with charge transfer between coupled chlorophyll and zeaxanthin molecules in the light-harvesting antenna of photosystem II (PSII). We found evidence for charge-transfer quenching in all three of the individual minor antenna complexes of PSII (CP29, CP26, and CP24), and we conclude that charge-transfer quenching in CP29 involves a delocalized state of an excitonically coupled chlorophyll dimer. We propose that reversible conformational changes in CP29 can "tune" the electronic coupling between the chlorophylls in this dimer, thereby modulating the energy of the chlorophyll-zeaxanthin charge-transfer state and switching on and off the charge-transfer quenching during qE.  相似文献   

Tests for the depolymerization of polyacrylamides as a potential source of acrylamide in heated foods     

Ahn JS  Castle L 《Journal of agricultural and food chemistry》2003,51(23):6715-6718

This study was conducted to test the possibility that polyacrylamides used in agriculture may contribute to acrylamide formation in heated foods by thermal depolymerization. Two samples of polyacrylamide with low molecular weights of 1.5 and 10 kDa were used to test for in-chain and end-chain depolymerization. They were added as aqueous solutions to filter paper for heating in a drying/dry environment and added to a cooking oil for heating in a fatty environment. The heating conditions were 175 degrees C for 15 and 30 min, respectively. Both regimens were tested in the absence and presence of the redox-active metal ions Fe(III) and Cu(II), and all tests were conducted without the exclusion of atmospheric oxygen. There was no evidence of any significant depolymerization of polyacrylamide to free acrylamide monomer, <0.04%. In fact, residual levels of acrylamide present already in the low molecular weight polymers were seen to fall by 50-80% on heating. Consequently, it is concluded that even if polyacrylamides were to contaminate agricultural crops and foods derived therefrom (which itself is an unproven suggestion), there is no evidence that the polymers would depolymerize on heating of the food to form acrylamide in any significant amount.  相似文献   

Hapten and antibody production for a sensitive immunoassay determining a human urinary metabolite of the pyrethroid insecticide permethrin   总被引：2，自引：0，他引：2  

Ahn KC  Watanabe T  Gee SJ  Hammock BD 《Journal of agricultural and food chemistry》2004,52(15):4583-4594

Permethrin is the most popular synthetic pyrethroid insecticide in agriculture and public health. For the development of the enzyme-linked immunosorbent assay (ELISA) to evaluate human exposure to permethrin, the glycine conjugate (DCCA-glycine) of a major metabolite, cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (DCCA), of permethrin was established as the target analyte. Four different types of the cis- and trans-isomers of immunizing haptens were synthesized as follows: N-(cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carbonyl)glycine (hapten 3), N-(cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carbonyl)-4-amino-l-phenylalanine (hapten 5), N-(N-(cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carbonyl)glycine)amino-6-(2,4-dinitrophenyl)aminohexanoic acid (hapten 9), and N-(cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carbonyl)glycine-4-oxobutanoic acid (hapten 24). Sixteen polyclonal antibodies produced against each cis- or trans-hapten-thyroglobulin conjugate as immunogens were screened against numerous hapten-bovine serum albumin conjugates as coating antigens. Six ELISAs with both a heterologous hapten structure and a heterologous hapten configuration (cis/trans or trans/cis) between antibody and coating antigen showed a high sensitivity for the target analyte. The IC50 was 1.3, 2.1, and 2.2 microg/L for the trans-target analyte and 0.4, 2.3, and 2.8 microg/L for the cis-target analyte. The immunizing haptens, except for hapten 5, provided the target specific antibodies. Molecular modeling of the haptens supported the selection of reasonable immunizing haptens that best mimicked the target analyte. Hapten 5 was suitable as a coating antigen rather than as an immunogen since it had a different geometry. Very low cross-reactivities were measured to permethrin, its free metabolite (DCCA), PBA-glycine conjugate, and glycine. The ELISA will be optimized for the detection of total cis/trans-DCCA-glycine in human urine samples.  相似文献   

Identification of QTLs for domestication-related and agronomic traits in an Oryza sativa×O. rufipogon BC¹F⁷ population     

S.-J. Lee    C.-S. Oh    J.-P. Suh    S. R. McCouch  S.-N. Ahn 《Plant Breeding》2005,124(3):209-219

Asian cultivated rice was domesticated from the wild rice, Oryza rufipogon and throughout the domestication process, a wide range of morphological and physiological changes altered the ancestral form. This study was conducted to identify the genetic basis of changes associated with the domestication process. An recombinant Inbred line (RIL) population consisting of 120 lines was developed from a cross between the Juponica cultivar.‘Hwayeongbyeo’and a presumed wild progenitor. O. rufipogon Griff. Acc.01944. The population was genotyped with 124 simple sequence length repeat (SSR) markers, providing an average interval size of 15 cM, and also evaluated for 20 traits related to domestication and agricultural performance. A total of 63 quantitative trait locus (QTLs) and one locus associated with qualitative variation for pericarp coloration were identified using single point and composite interval analysis. The number of QTLs per trait ranged from one to seven. Phenotypic variation associated with each QTL ranged from 3.7 to 40.4%. with an average of 15.3%. The results indicated that most domestication‐related traits clustered in chromosomal blocks, and the positions of many of these clusters were consistent with those reported in previous studies and with skewed segregation ratios in these BC₁,F₇ RILs. For 13 (20.6%) of the QTLs identified in this study. the O. rufipogan ‐derived allele contributed a desirable agronomic effect despite the overall undesirable characteristics of the wild phenotype. Favourable alleles from O. rufipogan were detected for panicle length, spikelets per panicle, days to heading and leaf discoloration associated with cold stress. When compared with previous studies involving interspecific crosses, it can be concluded that O. rufipogon is useful as a source of valuable alleles for rice improvement and that many of the introgressed regions contain genes that have a favourable impact on phenotype in different genetic backgrounds and different environments.  相似文献   

Ergot alkaloids reduce circulating serotonin in the bovine     

Eriton E L Valente  James L Klotz  Gyuchul Ahn  Kyle R McLeod  Hannah M Herzing  Mindy King  David L Harmon 《Journal of animal science》2020,98(12)

Ergot alkaloids can interact with several serotonin (5-hydroxytryptamine [5-HT]) receptors provoking many physiological responses. However, it is unknown whether ergot alkaloid consumption influences 5-HT or its metabolites. Thus, two experiments were performed to evaluate the effect of ergot alkaloid feeding on 5-HT metabolism. In exp. 1, 12 Holstein steers (260 ± 3 kg body weight [BW]) were used in a completely randomized design. The treatments were the dietary concentration of ergovaline: 0, 0.862, and 1.282 mg/kg of diet. The steers were fed ad libitum, kept in light and temperature cycles mimicking the summer, and had blood sampled before and 15 d after receiving the treatments. The consumption of ergot alkaloids provoked a linear decrease (P = 0.004) in serum 5-HT. However, serum 5-hydroxytryptophan and 5-hydroxyindoleacetic acid did not change (P > 0.05) between treatments. In exp. 2, four ruminally cannulated Holstein steers (318 ± 3 kg BW) were used in a 4 × 4 Latin square design to examine the difference between seed sources on 5-HT metabolism. Treatments were: control—tall fescue seeds free of ergovaline, KY 32 seeds (L42-16-2K32); 5Way—endophyte-infected seeds, 5 way (L152-11-1739); KY31—endophyte-infected seeds, KY 31 (M164-16-SOS); and Millennium—endophyte-infected seeds, 3rd Millennium (L108-11-76). The endophyte-infected seed treatments were all adjusted to provide an ergovaline dosage of 15 μg/kg BW. The basal diet provided 1.5-fold the net energy requirement for maintenance. The seed treatments were dosed directly into the rumen before feeding. The experiment lasted 84 d and was divided into four periods. In each period, the steers received seeds for 7 d followed by a 14-d washout. Blood samples were collected on day 0 (baseline) and day 7 for evaluating the treatment response in each period. A 24 h urine collection was performed on day 7. Similar to exp. 1, serum 5-HT decreased (P = 0.008) with the consumption of all endophyte-infected seed treatments. However, there was no difference (P > 0.05) between the infected seeds. The urinary excretion of 5-hydroxyindoleacetic acid in the urine was not affected (P > 0.05) by the presence of ergot alkaloids. In conclusion, the consumption of ergot alkaloids decreases serum 5-HT with no difference between the source of endophyte-infected seeds in the bovine.  相似文献