Multiple transatlantic introductions of the western corn rootworm     

Miller N  Estoup A  Toepfer S  Bourguet D  Lapchin L  Derridj S  Kim KS  Reynaud P  Furlan L  Guillemaud T 《Science (New York, N.Y.)》2005,310(5750):992

The invasion of Europe by the western corn rootworm, North America's most destructive corn pest, is ongoing and represents a serious threat to European agriculture. Because this pest was initially introduced in Central Europe, it was believed that subsequent outbreaks in Western Europe originated from this area. Using model-based Bayesian analyses of the genetic variability of the western corn rootworm, we demonstrate that this belief is false: There have been at least three independent introductions from North America during the past two decades. This result raises questions about changing circumstances that have enabled a sudden burst of transatlantic introductions.  相似文献   

Detection of Corynebacterium bovis infection in athymic nude mice from a research animal facility in Korea     

Tae-Hyoun Kim  Dong-Su Kim  Ju-Hee Han  Seo-Na Chang  Kyung-Sul Kim  Seung-Hyeok Seok  Dong-Jae Kim  Jong-Hwan Park  Jae-Hak Park 《Journal of veterinary science (Suw?n-si, Korea)》2014,15(4):583-586

Corynebacterium (C.) bovis infection in nude mice causes hyperkeratosis and weight loss and has been reported worldwide but not in Korea. In 2011, nude mice from an animal facility in Korea were found to have white flakes on their dorsal skin. Histopathological testing revealed that the mice had hyperkeratosis and Gram-positive bacteria were found in the skin. We identified isolated bacteria from the skin lesions as C. bovis using PCR and 16S rRNA sequencing. To the best of our knowledge, this is the first report of C. bovis infection in nude mice from Korea.  相似文献   

Preparation of silk sericin beads using LiCl/DMSO solvent and their potential as a drug carrier for oral administration   总被引：1，自引：0，他引：1  

Hanjin Oh  Ji Young Lee  Arum Kim  Chang Seok Ki  Jong Wook Kim  Young Hwan Park  Ki Hoon Lee 《Fibers and Polymers》2007,8(5):470-476

Silk sericin (SS) was fabricated into beads using LiCl/DMSO solution as a solvent. Up to 30 % (w/v) of SS could be dissolved within 3 hours, and the shape of solidified SS depends on the concentration of SS. Ethanol was the best coagulant among alcohols, making beads with suitable mechanical strength for further application. SS beads swell more at a pH above the isoelectric point (pl) than below the pl. The pH and the presence of an enzyme greatly affect the dissolution rate of SS beads. Whereas only 10 % of SS beads were dissolved at pH 2.2 in the presence of pepsin, more than 45 % of SS beads were dissolved at pH 7.4 in the presence of trypsin. The release of drug was suppressed in a stomach-like environment while promoted in an intestine-like environment.  相似文献   

Modeling of anisotropic creep behavior of coated textile membranes     

Woong-Ryeol Yu  Min Sun Kim  Joon Seok Lee 《Fibers and Polymers》2006,7(2):123-128

The present study aims at characterizing and modeling the anisotropic creep behavior of coated textile membrane, a class of flexible textile composites that are used for moderate span enclosures (roofs and air-halls). The objective is to develop a creep model for predicting the lifetime of coated textile membrane. Uniaxial creep tests were conducted on three off-axis coupon specimens to obtain the directional creep compliance. A potential with three parameters is shown to be adequate for modeling the anisotropic creep behavior of coated textile membrane. Furthermore, a possibility of predicting the creep deformation of coated textile membrane in a multi-axial stress state is discussed using the three-parameter potential.  相似文献   

Real-time identification of the draft system using neural network     

Soon Yong Chun  Han Jo Bae  Seon Mi Kim  Moon W. Suh  P. Grady  Won Seok Lyoo  Won Sik Yoon  Sung Soo Han 《Fibers and Polymers》2006,7(1):62-65

Making a good model is one of the most important aspects in the field of a control system. If one makes a good model, one is now ready to make a good controller for the system. The focus of this thesis lies on system modeling, the draft system in specific. In modeling for a draft system, one of the most common methods is the “least-square method”; however, this method can only be applied to linear systems. For this reason, the draft system, which is non-linear and a time-varying system, needs a new method. This thesis proposes a new method (the MLS method) and demonstrates a possible way of modeling even though a system has input noise and system noise. This thesis proved the adaptability and convergence of the MLS method.  相似文献   

Preparation of high molecular weight poly(methyl methacrylate) with high yield by room temperature suspension polymerization of methyl methacrylate     

Won?Seok?LyooEmail author  Seok?Kyun?Noh  Jeong?Hyun?Yeum  Gu?Chan?Kang  Han?Do?Ghim  Jinwon?Lee  Byung?Chul?Ji 《Fibers and Polymers》2004,5(1):75-81

To obtain high molecular weight (HMW) poly(methyl methacrylate) (PMMA) with high conversion, methyl methacrylate (MMA) was polymerized in suspension using a room temperature initiator, 2,2′-azobis(2,4-dimethylvaleronitrile) (ADMVN), and the effects of polymerization conditions on the polymerization behavior of MMA and the molecular parameters of PMMA were investigated. On the whole, the experimental results well corresponded to the theoretically predicted tendencies. These effects could be explained by a kinetic order of ADMVN concentration calculated by an initial rate method and an activation energy difference of polymerization obtained from the Arrhenius plot. Suspension polymerization at 25 °C by adopting ADMVN proved to be successful in obtaining PMMA of HMW (number-average degree of polymerization (P_n): 30,900–36,100) and of high yield (ultimate conversion of MMA into PMMA: 83–93 %) with diminishing heat generated during polymerization. The P_n and lightness were higher and polydispersity index was lower with PMMA polymerized at lower temperatures.  相似文献   

Crosslinking reaction of phenolic side chains in silk fibroin by tyrosinase     

Kang  Gyung Don  Lee  Ki Hoon  Ki  Chang Seok  Park  Young Hwan 《Fibers and Polymers》2004,5(3):234-238

Tyrosinase oxidizes the tyrosyl residues in silk fibroin (SF) with oxygen, resulting in the production ofo-quinone residues. Subsequently, the inter- or intramolecular crosslinks are formed by reaction with amino groups in through nonenzymatic process. The measurement of oxygen consumption proved that the tyrosyl residues in SF were mostly oxidized to quinone residues by tyrosinase. The reaction mechanisms were proposed in this study and the crosslinking reaction ofo-quinone residues and the enzymatic oxidation of tyrosyl residues could be confirmed by the measurements of UV,¹H-NMR and GFC.  相似文献   

Permeability measurement of a circular braided preform for resin transfer molding     

Yun?Kyoung?Cho  Young?Seok?Song  Tae?Jin?Kang  Kwansoo?Chung  Jae?Ryoun?YounEmail author 《Fibers and Polymers》2003,4(3):135-144

Permeability of the preform is one of key factors in design of RTM (Resin Transfer Molding) mold, determination of processing conditions, and modeling of flow in the mold. According to previous studies, permeability measured in the unsaturated fiber mats are higher than that in the saturated fiber mats by about 20 % because of the capillary pressure. In this study, permeabilities of several fiber preforms are measured for both saturated and unsaturated flows. A saturated experiment of radial flow has been adopted to measure the permeability of anisotropic fiber preforms with high fiber content, i.e., circular braided preforms. In this method, four pressure transducers are used to measure the pressure distribution. Permeabilities in different directions are determined and the experimental results show a good agreement with the theory. Since permeability is affected by the capillary effect, permeability should be measured in the unsaturated condition for the textile composites to be manufactured under lower pressure as in the Vacuum Assisted Resin Transfer Molding (VARTM).  相似文献   

Application of electrospun silk fibroin nanofibers as an immobilization support of enzyme   总被引：1，自引：0，他引：1  

Ki Hoon Lee  Chang Seok Ki  Doo Hyun Baek  Gyung Don Kang  Dae-Woo Ihm  Young Hwan Park 《Fibers and Polymers》2005,6(3):181-185

Silk fibroin (SF) nanofibers were prepared by electrospinning and their application as an enzyme immobilization support was attempted. By varying the concentration of SF dope solution the diameter of SF nanofiber was controlled. The SF nanofiber web had high capacity of enzyme loading, which reached to 5.6 wt%. The activity of immobilizedα-chymotrypsin (CT) on SF nanofiber was 8 times higher than that on silk fiber and it increased as the fiber diameter decreased. Sample SF8 (ca. 205 nm fiber diameter) has excellent stability at 25°C by retaining more than 90 % of initial activity after 24 hours, while sample SF11 (ca. 320 nm fiber diameter) shows higher stability in ethanol, retaining more than 45% of initial activity. The formation of multipoint attachment between enzyme and support might increase the stability of enzyme. From these results, it is expected that the electrospun SF nanofibers can be used as an excellent support for enzyme immobilization.  相似文献   

Distal aortic aneurysm presumed to be secondary to an infected umbilical artery in a foal     

RM Archer  SJG Gordon  HB Carslake  MG Collett 《New Zealand veterinary journal》2013,61(1):65-68

Abstract

CASE HISTORY:?A 3-month-old female Warmblood foal was presented after displaying signs of colic with pyrexia for 5 days.

CLINICAL AND PATHOLOGICAL FINDINGS:?The foal continued to show signs of colic, frequently passed urine, and was pyrexic with an elevated white blood cell count. The umbilical stalk was thickened but there was no evidence of purulent material. Exploratory laparotomy revealed an enlarged left umbilical artery remnant tightly adhered to the bladder wall. The left umbilical artery continued to an aneurysm involving the distal aorta. The foal was subject to euthanasia and post-mortem examination confirmed a spherical aortic aneurysm, in the dorsal midline caudal to the kidneys that contained a large thrombus. Histopathological examination revealed inflammation and necrosis of the tunica intima and tunica media of the left umbilical artery with suppuration and bacterial colonies evident in the periarterial tissues.

DIAGNOSIS:?Infected aortic aneurysm presumably caused by an umbilical artery infection.

CLINICAL RELEVANCE:?A previously undetected umbilical infection appears to have resulted in an unusual delayed complication causing signs of colic in a foal. Veterinarians should be aware of this condition, and the possibility that it may be a cause of signs of colic in foals. Diagnosis based on ultrasonography should be possible, but may require sedation, visceral analgesia and careful examination.  相似文献