• Title/Summary/Keyword: water-resistant

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Durability Enhancement in Nano-Silica Admixed Reinforced Mortar

  • Saraswathy, Velu;Karthick, Subbiah;Kwon, Seung-Jun
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.2 no.4
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    • pp.297-306
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    • 2014
  • Recently nano-materials are gaining more importance in the construction industry due to its enhanced energy efficiency, durability, economy, and sustainability. Nano-silica addition to cement based materials can control the degradation of the fundamental calcium-silicate-hydrate reaction of concrete caused by calcium leaching in water as well as block water penetration and therefore lead to improvements in durability. In this paper, the influence of synthesized nano silica from locally available rice husk on the mechanical properties and corrosion resistant properties of OPC (Ordinary Portland Cement) has been studied by conducting various experimental investigations. Micro structural properties have been assessed by conducting Scanning Electron Microscopy, Thermo gravimetry and Differential Thermal Analysis, X-Ray Diffraction analysis, and FTIR studies. The experimental results revealed that NS reacted with calcium hydroxide crystals in the cement paste and produces Calcium Silicate Hydrate gel which enhanced the strength and acts as a filler which filled the nano pores present in concrete. Hence the strength and corrosion resistant properties were enhanced than the control.

Listeria Species in Broiler Poultry Farms: Potential Public Health Hazards

  • Dahshan, Hesham;Merwad, Abdallah Mohamed Amin;Mohamed, Taisir Saber
    • Journal of Microbiology and Biotechnology
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    • v.26 no.9
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    • pp.1551-1556
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    • 2016
  • Broiler meat production worldwide has been plagued by lethal food-poisoning bacteria diseases, including listeriosis. A fatality rate of 15.6% was recorded in human beings in the EU in 2015. During 2013, a total of 200 poultry farm samples, including litter, chicken breast, farm feed, and drinking water, were collected to generate baseline data for the characterization of the genus Listeria in broiler poultry farms. Listeria spp. were detected in a total of 95 (47.5%) poultry farm samples. The isolates of Listeria spp. included L. innocua (28.5%), L. ivanovii (12.5%), L. welshimeri (4.5%), and L. monocytogenes and L. seeligeri (1% each). Listeria spp. contamination rates were higher in farm feed (70%), followed by litter (52.5%), chicken breasts (42.2%), and drinking water (10%). Almost all Listeria spp. isolates were resistant to more than three classes of antibiotics (multidrug resistant). Besides this, we observed a significant resistance level to penicillin and fluoroquinolone drugs. However, lower resistance levels were recorded for broad-spectrum cephalosporins. The inlA, inlC, and inlJ virulence genes were detected in almost all of the L. monocytogenes isolates. Thus, food safety management approaches and interventions at all stages of the broiler rearing cycle were needed to control cross-contamination and the zoonotic potential of listeriosis.

Proteomics in Insecticide Toxicology

  • Park, Byeoung-Soo;Lee, Sung-Eun
    • Molecular & Cellular Toxicology
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    • v.3 no.1
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    • pp.11-18
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    • 2007
  • Mechanisms of insecticide resistance found in insects may include three general categories. Modified behavioral mechanisms can let the insects avoid the exposure to toxic compounds. The second category is physiological mechanisms such as altered penetration, rapid excretion, lower rate transportation, or increased storage of insecticides by insects. The third category relies on biochemical mechanisms including the insensitivity of target sites to insecticides and enhanced detoxification rate by several detoxifying mechanisms. Insecticides metabolism usually results in the formation of more water-soluble and therefore more readily eliminated, and generally less toxic products to the host insects rather than the parent compounds. The representative detoxifying enzymes are general esterases and monooxygenases that catalyze the toxic compounds to be more water-soluble forms and then secondary metabolism is followed by conjugation reactions including those catalyzed by glutathione S-transferases (GSTs). However, a change in the resistant species is not easily determined and the levels of mRNAs do not necessarily predict the levels of the corresponding proteins in a cell. As genomics understands the expression of most of the genes in an organism after being stressed by toxic compounds, proteomics can determine the global protein changes in a cell. In this present review, it is suggested that the environmental proteomic application may be a good approach to understand the biochemical mechanisms of insecticide resistance in insects and to predict metabolomic changes leading to physiological changes of the resistant species.

Economical assessment and selection of corrosion protections for marine steel piles (해상 강관말뚝 활용을 위한 방식기법 선정 및 경제성 검토)

  • Lee, Ju-Hyung;Lee, Jong-Ku;Park, Jae-Hyun;Kwak, Ki-Seok;Chung, Moon-Kyung
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.03a
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    • pp.551-560
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    • 2009
  • Introduced was a new anti-corrosive method with improved ease of construction, economy, and durability that could be applicable for steel-composite drilled shaft. The feasibility and economy of sea-water-resistant steel was evaluated under the assumption that it was to substitute carbon steel for steel casing of drilled shaft foundation as a load carrying structural member not just as a sacrifice casing, and that anti-corrosive protection measures as required by the domestic standards was applied. Sea-water-resistant steel was found to cost 30% to 55% more, depending on pile diameter and the type of applied anti-corrosive measures, than carbon steel for the service life time of 70 years: 50% to 90% more for 100 years of service life.

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Experimental assessment for friendly-environment functional Inorganic mixed rubber asphalt Seismic waterproof strengthening method (친환경 기능성 무기질계와 고무아스팔트를 혼합한 내진방수 보강공법에 대한 실험적 평가)

  • Baek, Jong-Myeong;Hwang, Young-Ho;Shon, Jung-Chul
    • Proceedings of the KSR Conference
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    • 2008.06a
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    • pp.1802-1808
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    • 2008
  • Recent interest in the construction sector, rising about the environment and eco-friendly recycled material resources, and increase the development of method But despite these efforts, and the diverse functional and structural changes in the structure can not be an appropriate response to the functional waterproof structural changes in the structures and appropriate response Diversification does not waterproof and functional issues such as durability, and which are occurring due to the structure to secure stability and durability, never sees the conservative economic losses due to import constructability reinforcement situation. Therefore, this study applies to structure the existing waterproof method (hereinafter referred to as structures water-resistant methode), and to review recent issues of environmental pollution and resource waste, and taking on environmental issues, such as Revelation and functional Inorganic mixed in a way to leverage the manufacturing water-resistant material "Re Inorganic, functional and environmentally friendly high-viscosity mix asphalt waterproof rubber reinforcements, and taking conservative" for the characterization and performance assessment to the issues raised by the structure and whether the judge would respond.

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Membrane Based Removal of Antibiotics from Wastewater: A Review (폐수중 항생제의 막기반 제거에 관한 연구: 검토)

  • Ryoo Wanki;Rajkumar Patel
    • Membrane Journal
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    • v.34 no.2
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    • pp.96-104
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    • 2024
  • Antibiotics is one of the emerging pollutants found in various water sources as well as wastewater due to its excessive use. Different techniques are available for treating antibiotics contaminants in water such as advanced oxidation process and biological treatment etc. These two processes are ineffective, and the generation of side products makes this process more complicated. Membrane technology is another alternative for the removal of contaminants. To improve the removal of antibiotics and their resistant gene, membrane bioreactors are modified with NaClO and carbon materials. The generation of abundant reactive species is active against the antibiotic's resistant genes.

Study on the alternatives to trace the origin and to diminish the sediments of drinking water (수돗물의 앙금발생규명 및 저감기술방안)

  • 김갑수;임병진;권은미
    • Journal of environmental and Sanitary engineering
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    • v.9 no.1
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    • pp.17-28
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    • 1994
  • There are many possibilities that may lead to low quality of drinking water Recently, some unknown deposits in tap water raised a lot of public concern regarding the safety of drinking water in Seoul. We analyzed the quality of tap water from several areas of Seoul, including the area where public complaints about tap water were high. The results shows that the quality of tap water in Seoul was good, well below the environmental standards. Only the tap water from the area with high public complaints showed turbidity higher than that of other area. Also, result shows that component of deposit in tap water was Al, Fe, Mn, and Zn. Based on the research result we propose several measures that might help to reduce the amount of deposit in tap water as follows : 1 Using coagulant aid when coagulating or adjusting pH when filtering. 2. Replacing old water pipeline with new corrosive- resistant one. 3. Increasing water treatment efficiency by enhancing water treatment system such as automation of water treatment system adjusting production capacity, and improving operational condition of filler basin. 4. Chlorine disinfection at the distribution reservoir would help maintaining the same pH level and chlorine concentration throughout the water pipeline and reduce corrosion of pipe.

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A Study on the Degradability of Pharmaceuticals during UV Treatment (자외선 처리시의 의약품류의 분해도에 관한 연구)

  • Kim, Ilho
    • Journal of Korean Society on Water Environment
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    • v.28 no.6
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    • pp.902-910
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    • 2012
  • The photodegradation characteristics of 30 pharmaceuticals were investigated by batch experiments using Ultraviolet (UV) reactor. The investigated pharmaceuticals include antibiotics, analgesics and antiarrhythmic agents etc. Tested water was prepared by simultaneously spiking 30 pharmaceuticals into pure water, and each experiment was conducted using 3 types of UV lamps. As a result, batch experiments showed that reactions of all the investigated pharmaceuticals followed pseudo-first order reaction regardless of the applied UV lamps. Among the pharmaceuticals, Cyclophosphamide, 2-Quinoxaline carboxylic acid and Clarithromycin proved to be the most UV-resistant compounds. Contrarily, Ceftiofur, Diclofenac and Ketoprofen were easily degraded by all the UV lamps. Dissolved organic carbon (DOC) concentration hardly changed although the concentration of the pharmaceuticals concentration gradually decreased with time, indicating that the degradation of parent pharmaceuticals may produce their intermediates during UV treatment.

Study on Water Treatment Improvement Measures based on Case Studies of Ozone Disinfection at Domestic Water Treatment Plants (국내 정수장의 오존 소독능 평가사례를 통한 정수처리기준 개선방안 연구)

  • Noh, Hee-Su;Lee, Kyung-Hyuk;Wang, Chang-Keun;Son, Dae-Ik;Kang, Joon-Wun
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.2
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    • pp.153-160
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    • 2011
  • Ozone process is currently applied in 24 water treatment plants in Korea to control micropollutants and taste & odor compounds. However, one of the chlorine resistant protozoa, cryptosporidium, is not being considered as ozone disinfection performance whereas U.S. is already regulate Cryptosporidium by ozone disinfection. two ozone plants(PH, UH WTP) operation conditions are investigated for disinfection performance comparing Korea disinfection regulation and U.S. regulation. The ozone plants are unable to get Cryptosporidium inactivation credits by Korea disinfection regulation. However, the inactivation credit for Cryptosporidum was increased when the U.S. disinfection regulation was applied. The Korea disinfection credit regulation need revision to practical aspects.

Antibacterial Activity of Water Extract of Green Tea against Pathogenic Bacteria (식중독세균에 대한 녹차 물추출물의 항균작용)

  • 박찬성
    • Food Science and Preservation
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    • v.5 no.3
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    • pp.286-291
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    • 1998
  • The sensitivity of various pathogenic bacteria(Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus 196E, Salmonella typhimurium) to the water extract of green tea was tested. Tryptic soy broth was inoculated with 10$\^$5/CPU/ml of pathogenic bacteria and incubated at 35$^{\circ}C$ for 30 hours. The extract was added at a final concentration of 0-2%(w/v) into culture broth at the mid or late exponential phase of bacteria. The growth of pathogenic bacteria was inhibited with increasing concentrations of the extract in culture broth and the late exponential phase cells were more resistant than the mid exponential phase cells. Cram positive bacteria(L. monocytogenes and S. aureus 196E) were more sensitive than Cram negative bacteria(E. coli O157:H7 and S. typhimurium). S. aureus had the highest sensitivity, followed by L monocytogenes, E. coli O157:H7. S. typhimurium was the most resistant to the water extract of green tea.

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