Effects of residue management on nitrogen losses in surface and sub-surface water from sugarcane fields     

Chang Yoon Jeong  Alan DeRamus  Jim J. Wang  Lora L. Goodeaux 《Archives of Agronomy and Soil Science》2013,59(1):103-118

The effect of three sugarcane (Saccharum officinarum L.) residue-management plans on nitrogen losses in surface runoff and sub-surface leachate was studied for 3 years. The three management plans evaluated were conventional burning (CB), compost application with burning (COMB), and remaining green cane trash blanketing (GCTB) treatment. In the CB treatment, sugarcane residue was burned after harvest. The COMB treatment consisted of compost applied at ‘off bar’ with sugarcane residue burned immediately after harvest. Compost was applied in the amount of 13.4 Mg ha^?1 annually. Surface runoff was collected with automatic refrigerated samplers and sub-surface leachate was collected with pan lysimeters over a period of 3 years. Total nitrogen (TN), NO₃/NO₂–N, and NH₄–N were measured. The mean losses of nitrogen (TN, NO₃/NO₂–N, and NH₄–N) from the COMB treatment after the burning procedure (post-harvest, years 2 and 3) were on average 2.7 times higher than those before harvest and burning (pre-harvest, year 1). Mean leaching losses of NO₃/NO₂–N were 0.36, 0.82, and 0.10 kg ha^?1 for the CB, COMB, and GCTB treatment, respectively. The losses of NO₃/NO₂–N from the GCTB treatment in surface runoff and sub-surface leachate were significantly reduced compared to the CB and COMB treatment.  相似文献   

The mechanical properties of polyurethane foam wound dressing hybridized with alginate hydrogel and jute fiber     

Seung-Taek Oh  Sung-Hoon Kim  Heon-Young Jeong  Jung-Min Lee  Jae Whan Cho  Jong-Shin Park 《Fibers and Polymers》2013,14(2):173-181

The purpose of this study is to fabricate a smart wound dressing by hybridizing hydrophilic polyurethane foam (PUF) and alginate hydrogel. Hydrophilic PUF is used to maintain damaged tissue in a moist environment. Despite its many strong points as a wound dressing, hydrophilic PUF cannot be loaded with ingredients such as growth factors and cytokines that would enhance wound healing. Therefore, we introduce a pH-sensitive alginate hydrogel with the ability to selectively release drugs within the pH range of wounded skin. Due to the small pore size of PUF and the high viscosity of the alginate solution, the two are not easily penetrable. As such, a vacuum method is used to insert alginate hydrogel into the PUF. The optimum conditions for the vacuum method chosen are to be proposed. However, the mechanical strength of PUF decreased after containing alginate hydrogel. Therefore, Na-alginate powder for PUF, various types of crosslinking agents and jute fiber for alginate hydrogel were introduced to improve the mechanical properties of hydrogel/PUF hybrid wound dressing. Three different types of crosslinking agents are used for the gel formation. The most suitable crosslinking agent and its concentration for alginate hydrogel is also determined by the experiments. The experimental results are discussed with proper schemes and reasonable explanations.  相似文献   

Compressive viscoelastic properties of softwood kraft lignin-based flexible polyurethane foams   总被引：1，自引：0，他引：1  

Heonyoung Jeong  Jongshin Park  Sunghoon Kim  Jungmin Lee  Narang Ahn 《Fibers and Polymers》2013,14(8):1301-1310

Softwood kraft lignin (SKL)-based water-blown flexible polyurethane foams were prepared using SKL as a crosslinking agent and a hard segment polyol. Polyethylene glycol (PEG) as a soft segment diol and 2,4-toluene diisocyanate (TDI) were used. While increasing hard segment content caused the increase in crosslink density in foams, the foams became more and more viscous with increasing hard segment content due to the distinctive phase heterogeneity in foams. In this case, the contributiveness of the filler-like behaviors of separated hard segments always overtook the crosslinking effects derived from SKL in terms of overall viscoelasticity, thus the resultant viscometric properties such as tanδ _max and hysteresis loss increased as hard segment content increased. Furthermore, increasing M _n,PEG caused the severer microphase separation and intensified the filler effects in foams, thus the foams became more viscous with increasing M _n,PEG. The 25 % and 65 % CFD values and Young’s moduli of foams increased with increasing hard segment content due to the increase in crosslink density for foams, and the properties also increased with increasing foam density. Most of foams showed the support factors in the range of 2–3, which are suitable values for cushioning use. Even though the microscopic deformation behaviors in foams are irrelevant to foam density, the cyclic compressive tests showed that the higher foam density possess the better shape recovery performances.  相似文献   

Fabrication and surface modification of melt-electrospun poly(D,L-lactic-co-glycolic acid) microfibers     

Sung Jin Kim  Lim Jeong  Seung Jin Lee  Donghwan Cho  Won Ho Park 《Fibers and Polymers》2013,14(9):1491-1496

In this study, biodegradable poly(D,L-lactic-co-glycolic acid) (PLGA) fibers were prepared by a melt-electrospinning and treated with plasma in the presence of either oxygen or ammonia gas to modify the surface of the fibers. The effects of processing parameters on the melt-electrospinning of PLGA were examined in terms of fiber morphology and diameter. Among the processing parameters, the spinning temperature and mass flow rate had a significant effect on the average fiber diameter and its distribution. The water contact angle of melt-electrospun PLGA fibers decreased significantly from 123 ° to 55 ° (oxygen plasma treatment) or to 0 ° (ammonia plasma treatment) by plasma treatment for 180 sec, while their water content increased significantly from 2.4 % to 123 % (oxygen plasma treatment) or to 189 % (ammonia plasma treatment). Ammonia gas-plasma enhanced the surface hydrophilicity of PLGA fibers more effectively compared to oxygen gas-plasma. X-ray photoelectron spectroscopy analysis supported that the number of polar groups, such as hydroxyl and amino groups, on the surface of PLGA fibers increased after plasma treatment. Overall, the microfibrous PLGA scaffolds with appropriate surface hydrophilicity and fiber diameter could be fabricated by melt electrospinning and subsequent plasma treatment, without a significant deterioration of fiber structure and dimensional stability. This approach of controlling the surface properties and structures of fibers could be useful in the design and tailoring of novel scaffolds for tissue engineering.  相似文献   

Increased environmental stability of a tungsten bronze NIR-absorbing window     

Wi Hyoung Lee  Hyunmin Hwang  Kyunghwan Moon  Kwonwoo Shin  Jong Hun Han  Soong Ho Um  Juhyun Park  Jeong Ho Cho 《Fibers and Polymers》2013,14(12):2077-2082

We developed a facile method for increasing the environmental stability of a tungsten bronze near-infrared (NIR)-absorbing window using tetraethyl orthosilicate (TEOS) and 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (FDS). The environmental stability of the tungsten bronze NIR-absorbing window could be enhanced by applying a variety of protective layers (i.e., TEOS, fluoropolymer (CYTOP), FDS). The protective characteristics of each layer type are discussed. The protection of tungsten bronze surfaces by TEOS and FDS layers enormously enhanced the environmental stability of the NIR absorbing window, whereas an untreated tungsten bronze film rapidly lost its NIR absorption properties. The protection efficiency followed the order: TEOS/FDS>FDS>TEOS>CYTOP. The improved environmental stability arose from the closely packed structure of FDS, which can self-assemble on an oxide surface, such as the tungsten oxide or silicon oxide surfaces. The method developed here provides a simple, robust, and versatile way to improve the environmental stability of a NIR-absorbing window.  相似文献   

Simultaneous enhancement of impact toughness, mechanical properties and thermo-dimensional stability of epoxy composites by rubber-coated exfoliated graphite nanoplatelets     

Jeong Hyeon Hwang  Donghwan Cho 《Fibers and Polymers》2013,14(11):1947-1952

Exfoliated graphite nanoplatelets (EGN) were successfully coated with a liquid rubber amine-terminated poly(butadiene-co-acrylonitrile) (ATBN) at various concentrations. The rubber-coated EGN was incorporated into epoxy resin at different contents. The result revealed that the impact toughness of EGN/epoxy composite was increased by about 18 % with increasing the ATBN coating concentration. The impact strength, the flexural and dynamic mechanical properties, and the thermo-dimensional stability of EGN/epoxy composites were simultaneously enhanced by the incorporation of 1 wt% EGN coated with 10 wt% ATBN rubber into epoxy, which turns out a very small amount of 0.1 wt% ATBN compared to the epoxy resin.  相似文献   

High-resolution EM of colloidal nanocrystal growth using graphene liquid cells     

Yuk JM  Park J  Ercius P  Kim K  Hellebusch DJ  Crommie MF  Lee JY  Zettl A  Alivisatos AP 《Science (New York, N.Y.)》2012,336(6077):61-64

We introduce a new type of liquid cell for in situ transmission electron microscopy (TEM) based on entrapment of a liquid film between layers of graphene. The graphene liquid cell facilitates atomic-level resolution imaging while sustaining the most realistic liquid conditions achievable under electron-beam radiation. We employ this cell to explore the mechanism of colloidal platinum nanocrystal growth. Direct atomic-resolution imaging allows us to visualize critical steps in the process, including site-selective coalescence, structural reshaping after coalescence, and surface faceting.  相似文献   

Evaluation of recombinant 28 kDa outer membrane protein of Brucella abortus for the clinical diagnosis of bovine brucellosis in Korea     

Lim JJ  Kim DH  Lee JJ  Kim DG  Min W  Lee HJ  Rhee MH  Chang HH  Kim S 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2012,74(6):687-691

Brucella spp. are Gram-negative, facultative, intracellular coccobacilli that are pathogenic to a variety of mammals, including ruminants and humans. The conventional serological test for diagnosing brucellosis in cattle in Korea is the standard tube agglutination test. However, agglutination tests sometimes give false-positive results due to cross-reactions with other pathogens. The outer membrane proteins of Brucella species have been extensively studied for their immunogenicity and serodiagnostic applications. However, an application of B. abortus OMPs for serodiagnosis has not been successfully established. In this study, cloning and expression of B. abortus Omp28, a group 3 antigen, were accomplished by PCR amplification cloning into a pMAL expression system, and purification of a recombinant Omp28 (rOmp28). The immunogenicity of rOmp28 was confirmed by Western blot analysis with Brucella-positive bovine serum. To determine whether rOmp2 has a potential benefit for use in the serodiagnosis of bovine brucellosis, rOmp28-based ELISA and latex bead agglutination test were performed. B. abortus positive (n=122) or negative (n=88) from TAT were positive (118/122, 96.7%) or negative (84/88, 95.4%) in ELISA and were positive (94/122, 77%) or negative (71/88, 81.7%) in that the latex bead agglutination test, respectively. The sensitivity, specificity and accuracy were 96.7, 95.4, 96.2% in ELISA and 77, 80.6, 78.5% in latex bead agglutination test, respectively. These findings suggest that the rOmp28 of B. abortus might be a good candidate for developing serological diagnostic tools for bovine brucellosis.  相似文献   

Prevalence of Lawsonia intracellularis, Salmonella spp. and Eimeria spp. in healthy and diarrheic pet rabbits     

Lim JJ  Kim DH  Lee JJ  Kim DG  Kim SH  Min W  Chang HH  Rhee MH  Kim S 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2012,74(2):263-265

A total of 170 fresh fecal samples (healthy; n=137, diarrheic; n=33) were collected from pet rabbits. By using PCR and formol-ether concentration method, a total 13/137 healthy rabbit feces were positive for L. intracellularis, 6/137 for Salmonella, and 13/137 for Eimeria. On the other hand, a total 17/33 diarrheic rabbit fecal samples were positive for L. intracellularis, 10/33 for Salmonella, and 21/33 for Eimeria. From these results, more than 20% of clinically normal and 97% of diarrheic rabbits were positive for single or concurrent infection of three pathogens. To the best of our knowledge, this is the first report to describe the prevalence of the microorganisms L. intracellularis, Salmonella and Eimeria in pet rabbits.  相似文献   

Protective effects of recombinant Brucella abortus Omp28 against infection with a virulent strain of Brucella abortus 544 in mice   总被引：1，自引：0，他引：1  

Jeong Ju Lim  Dong Hyeok Kim  Jin Ju Lee  Dae Geun Kim  Wongi Min  Hu Jang Lee  Man Hee Rhee  Suk Kim 《Journal of veterinary science (Suw?n-si, Korea)》2012,13(3):287-292

The outer membrane proteins (OMPs) of Brucella (B.) abortus have been extensively studied, but their immunogenicity and protective ability against B. abortus infection are still unclear. In the present study, B. abortus Omp28, a group 3 antigen, was amplified by PCR and cloned into a maltose fusion protein expression system. Recombinant Omp28 (rOmp28) was expressed in Escherichia coli and was then purified. Immunogenicity of rOmp28 was confirmed by Western blot analysis with Brucella-positive mouse serum. Furthermore, humoral- or cell-mediated immune responses measured by the production of IgG1 or IgG2a in rOmp28-immunized mice and the ability of rOmp28 immunization to protect against B. abortus infection were evaluated in a mouse model. In the immunogenicity analysis, the mean titers of IgG1 and IgG2a produced by rOmp28-immunized mice were 20-fold higher than those of PBS-treated mice throughout the entire experimental period. Furthermore, spleen proliferation and bacterial burden in the spleen of rOmp28-immunized mice were approximately 1.5-fold lower than those of PBS-treated mice when challenged with virulent B. abortus. These findings suggest that rOmp28 from B. abortus is a good candidate for manufacturing an effective subunit vaccine against B. abortus infection in animals.  相似文献