The common bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), is an ectoparasitic pest that feeds on humans as well as other mammals. We investigate that point mutations on the voltage-sensitive sodium channel are associated with the resistance to pyrethroids. Two point mutations (V419L and L925I) in the voltage-sensitive sodium channel (VSSC) α-subunit gene have been identified in deltamethrin-resistant bed bugs. L925I, located the intracellular loop between IIS4 and IIS5, has been previously found in a highly pyrethroid-resistant populations of whitefly. V419L, located in the IS6 transmembrane segment, is a novel mutation. To establish a population-based genotyping method as a molecular resistance monitoring tool, a quantitative sequencing (QS) protocol was developed. Frequency prediction equations were generated from the plots by linear regression, and the signal ratios were shown to highly correlate with resistance allele frequencies (r2 > 0.993). In addition to QS, the filter contact vial bioassay (FCVB) method was established and used to determine the baseline susceptibility and resistance of bed bugs to pyrethroids. A pyrethroid-resistant strain showed > 9375- and 6990-fold resistance to deltamethrin and λ-cyhalothrin, respectively. Resistance allele frequencies in different bed bug populations predicted by QS correlated well with the FCVB results, confirming the roles of the two mutations in pyrethroid resistance. Taken together, employment of QS in conjunction with FCVB method should greatly facilitate the detection and monitoring of pyrethroid resistant bed bugs in the field.

The present investigation establishes deltamethrin resistance in the common bed bug, Cimex lectularius, populationcollected from New York City (NY-BB). The mortality resistance ratio indicated that NY-BB population was 264-fold more resistant to 1% deltamethrin in contact bioassay compared to one insecticide- susceptible population collected in Florida (FL-BB). Specific enzyme activities (general esterase, glutathione S-transferase, and 7-ethoxycoumarin O-deethylase) of NY-BB were not statistically different from those of FL-BB, indicating that the metabolic factors are not associated with the deltamethrin resistance in NY-BB. Complementary DNA fragments that encoded the open reading frame of voltage-sensitive sodium channel α-subunit genes from the FL-BB and NY-BB were obtained by homology probing PCR and sequenced. Sequence alignment of the internal and 5’ and 3’ RACE fragments generated a 6500 bp cDNA sequence contig, which was composed of a 6084 bp open reading frame (ORF) encoding 2027 amino acid residues and 186 bp 5’ and 230 bp 3’ untranslated regions (5’ and 3’UTRs, respectively). Sequence comparisons of the complete open reading frames of the sodium channel genes identified two point mutations (V419L and L925I) that were presented only in the NY-BB population. L925I, located the intracellular loop between IIS4 and IIS5, has been previously found in the pyrethroid-resistant populations of whitefly (Bemisia tabaci) that was more than 100-fold resistant to fenpropathrin. V419L, located in the IS6 transmembrane segment, is a novel mutation. This evidence suggests that the two mutations are likely the major resistance-causing mutations in the deltamethrin-resistant NY-BB via a knockdown-type nerve insensitivity mechanism.

Adsorption of phenol on activated carbon in a fixed bed was studied. The effects of fixed-bed length, superficial velocity (flow rate) and particle size of adsorbent on fixed-bed performance were investigated. Some characteristic parameters such as the breakthrough time (t0.05), saturation time (t0.95), length of mass transfer zone (LMTZ), adsorptive capacity (W), and adsorption rate constant (Ka) were derived from the breakthrough curves. Adsorbent particle sizes significantly affected the shape of the breakthrough curve. Larger particle sizes resulted in an earlier breakthrough, a longer LMTZ and a lower adsorption rate. Superficial velocity was a critical factor for the external mass transfer during fixed-bed adsorption process. The external mass transfer resistance was dominant as increasing superficial velocity.

본 연구는 하상마찰의 척도인 등가조고를 이용하여 자갈하천의 하상저항을 산정하는 것이다. 이를 위하여 국내 8개 자갈하천에서 실측을 통하여 마찰계수 f를 산정하였고, 하상재료의 누가입경분포를 조사하였으며, 각 단면의 실측 마찰계수를 나타내기 위하여 대수 연직유속분포를 가정하여 계산된 평균 등가조고와 누가입경분포를 이용하여 계산된 구간 등가조고를 비교하였다. 더불어 등가조고를 사용하여 계산된 Manning 계수를 Strickler 유형의 기존 경험식에 의한

In this study, we estimated the equivalent roughness using an estimation model, which considered grain distribution on the bed and the protrusion height of the grains. We also reviewed the appropriateness of the estimated equivalent roughness at the Goksung and Gurey station in the Seomjin River. To review the appropriateness of this model, we presented the water level-discharge relation curve applying the equivalent roughness to the flow model and compared and reviewed it to observed data. Also, we compared and reviewed the observed data by estimating the Manning coefficient , the Chezy coefficient , and the Darcy-Weisbach friction coefficient by the equivalent roughness. The calculation results of the RMSE showed within 5% error range in comparison with observed value. Therefore the estimated equivalent roughness values by the model could be proved appropriate.

Flow resistance in a natural stream is caused by complex factors, such as the grains on the bed, vegetation, and bed-form, reach profile. Flow resistance in a generally stable gravel bed stream is due to protrudent grains from bed. Therefore, the flow resistance can be calculated by equivalent roughness in gravel bed stream, but estimation of equivalent roughness is difficult because nonuniform size and irregular arrangement of distributed grain on natural stream bed. In previous study, equivalent roughness is empirically estimated using characteristic grain size. However, application of empirical equation have uncertainty in stream that stream bed characteristic differs. In this study, we developed a model using an analytical method considering grain diameter distribution characteristics of grains on the bed and also taking into account flow resistance acting on each grain. Also, the model consider the protrusion height of grain.