• Title/Summary/Keyword: Acid Resistance

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Research on the development of the properties of PLA composites for automotive interior parts (자동차 내장재 적용을 위한 PLA 복합재료의 물성개선에 관한 연구)

  • Jung, Jae-Won;Kim, Seong-Ho;Kim, Si-Hwan;Park, Jong-Kyoo;Lee, Woo-Il
    • Composites Research
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    • v.24 no.3
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    • pp.1-5
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    • 2011
  • Since the environmental problems and new stricter regulations are forcing the industries to introduce more ecological materials for their products, biodegradable materials have attracted increasing attention. Among these materials, Polylactic acid(PLA) is a promising candidate for its modulus, strength, chemical resistance. However, PLA could not be used for automobile industries for its low heat resistance and impact strength. In this study natural fibers were (jute fiber was) introduced as reinforcements in order to improve heat resistance and impact strength of PLA. Especially for improving the adhesion between PLA and jute, various surface treatments were tried. With each treatment, we verified that the impact strength of composite was improved. With annealing treatment, we found a remarkable increase of heat resistance of PLA composite.

Resistance Induction by Salicylic Acid Formulation in Cassava Plant against Fusarium solani

  • Saengchan, Chanon;Phansak, Piyaporn;Thumanu, Kanjana;Siriwong, Supatcharee;Le Thanh, Toan;Sangpueak, Rungthip;Thepbandit, Wannaporn;Papathoti, Narendra Kumar;Buensanteai, Natthiya
    • The Plant Pathology Journal
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    • v.38 no.3
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    • pp.212-219
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    • 2022
  • Fusarium root rot caused by the soil-borne fungus Fusarium solani is one of the most important fungal diseases of cassava in Thailand, resulting in high yield losses of more than 80%. This study aimed to investigate if the exogenous application of salicylic acid formulations (Zacha) can induce resistance in cassava against Fusarium root rot and observe the biochemical changes in induced cassava leaf tissues through synchrotron radiation based on Fourier-transform infrared (SR-FTIR) microspectroscopy. We demonstrated that the application of Zacha11 prototype formulations could induce resistance against Fusarium root rot in cassava. The in vitro experimental results showed that Zacha11 prototype formulations inhibited the growth of F. solani at approximately 34.83%. Furthermore, a significant reduction in the disease severity of Fusarium root rot disease at 60 days after challenge inoculation was observed in cassava plants treated with Zacha11 at a concentration of 500 ppm (9.0%). Population densities of F. solani were determined at 7 days after inoculation. Treatment of the Zacha11 at a concentration of 500 ppm resulted in reduced populations compared with the distilled water control and differences among treatment means at each assay date. Moreover, the SR-FTIR spectral changes of Zacha11-treated epidermal tissues of leaves had higher integral areas of lipids, lignins, and pectins (1,770-1,700/cm), amide I (1,700-1,600/cm), amide II (1,600-1,500/cm), hemicellulose, lignin (1,300-1,200/cm), and cellulose (1,155/cm). Therefore, alteration in defensive carbohydrates, lipids, and proteins contributed to generate barriers against Fusarium invasion in cassava roots, leading to lower the root rot disease severity.

Antimicrobial Resistance of Seventy Lactic Acid Bacteria Isolated from Commercial Probiotics in Korea

  • Eunju Shin;Jennifer Jaemin Paek;Yeonhee Lee
    • Journal of Microbiology and Biotechnology
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    • v.33 no.4
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    • pp.500-510
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    • 2023
  • In this study, lactic acid bacteria were isolated from 21 top-selling probiotic products on Korean market and their antimicrobial resistance were analyzed. A total 152 strains were claimed to be contained in these products and 70 isolates belonging to three genera (Bifidobacterium, Lactobacillus, and Lactococcus) were obtained from these products. RAPD-PCR showed diversity among isolates of the same species except for two isolates of Lacticaibacillus rhamnosus from two different products. The agar dilution method and the broth dilution method produced different MICs for several antimicrobials. With the agar dilution method, five isolates (three isolates of Bifidobacterium animalis subsp. lactis, one isolate of B. breve, one isolate of B. longum) were susceptible to all nine antimicrobials and 15 isolates were multi-drug resistant. With the broth microdilution method, only two isolates (one isolate of B. breve and one isolate of B. longum) were susceptible while 16 isolates were multi-drug resistant. In this study, only two AMR genes were detected: 1) lnu(A) in one isolate of clindamycin-susceptible and lincomycin-resistant Limosilactobacillus reuteri; and 2) tet(W) in one tetracycline-susceptible isolate of B. longum B1-1 and two tetracycline-susceptible isolates and three tetracycline resistant isolates of B. animalis subsp. lactis. Transfer of these two genes via conjugation with a filter mating technique was not observed. These results suggest a need to monitor antimicrobial resistance in newly registered probiotics as well as probiotics with a long history of use.

Animal protein hydrolysate reduces visceral fat and inhibits insulin resistance and hepatic steatosis in aged mice

  • Su-Kyung Shin;Ji-Yoon Lee;Heekyong R. Bae;Hae-Jin Park;Eun-Young Kwon
    • Nutrition Research and Practice
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    • v.18 no.1
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    • pp.46-61
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    • 2024
  • BACKGROUND/OBJECTIVES: An increasing life expectancy in society has burdened healthcare systems substantially because of the rising prevalence of age-related metabolic diseases. This study compared the effects of animal protein hydrolysate (APH) and casein on metabolic diseases using aged mice. MATERIALS/METHODS: Eight-week-old and 50-week-old C57BL/6J mice were used as the non-aged (YC group) and aged controls (NC group), respectively. The aged mice were divided randomly into 3 groups (NC, low-APH [LP], and high-APH [HP] and fed each experimental diet for 12 weeks. In the LP and HP groups, casein in the AIN-93G diet was substituted with 16 kcal% and 24 kcal% APH, respectively. The mice were sacrificed when they were 63-week-old, and plasma and hepatic lipid, white adipose tissue weight, hepatic glucose, lipid, and antioxidant enzyme activities, immunohistochemistry staining, and mRNA expression related to the glucose metabolism on liver and muscle were analyzed. RESULTS: Supplementation of APH in aging mice resulted in a significant decrease in visceral fat (epididymal, perirenal, retroperitoneal, and mesenteric fat) compared to the negative control (NC) group. The intraperitoneal glucose tolerance test and area under the curve analysis revealed insulin resistance in the NC group, which was alleviated by APH supplementation. APH supplementation reduced hepatic gluconeogenesis and increased glucose utilization in the liver and muscle. Furthermore, APH supplementation improved hepatic steatosis by reducing the hepatic fatty acid and phosphatidate phosphatase activity while increasing the hepatic carnitine palmitoyltransferase activity. Furthermore, in the APH supplementation groups, the red blood cell (RBC) thiobarbituric acid reactive substances and hepatic H2O2 levels decreased, and the RBC glutathione, hepatic catalase, and glutathione peroxidase activities increased. CONCLUSIONS: APH supplementation reduced visceral fat accumulation and alleviated obesity-related metabolic diseases, including insulin resistance and hepatic steatosis, in aged mice. Therefore, high-quality animal protein APH that reduces the molecular weight and enhances the protein digestibility-corrected amino acid score has potential as a dietary supplement for healthy aging.

Effects of Citric Acid as a Complexing Agent on Material Removal in Cu CMP (Cu CMP에서 Citric Acid가 재료 제거에 미치는 영향)

  • Jung Won-Duck;Park Boum-Young;Lee Hyun-Seop;Jeong Hea-Do
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.10
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    • pp.889-893
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    • 2006
  • Chemical mechanical polishing (CMP) achieves surface planrity through combined mechanical and chemical means. The role of slurry is very important in metal CMP. Slurry used in metal CMP normally consists of oxidizers, complexing agents, corrosion inhibitors and abrasives. This paper investigates the effects of citric acid as a complexing agent for Cu CMP with $H_2O_2$. In order to study chemical effects of citric acid, X-ray photoelectron spectroscopy (XPS) was peformed on Cu sample after etching test. XPS results reveal that CuO, $Cu(OH)_2$ layer decrease but $CU/CU_2O$ layer increase on Cu sample surface. To investigate nanomechanical properties of Cu sample surface, nanoindentation was performed on Cu sample. Results of nanoindentation indicate wear resistance of Cu surface decrease. According to decrease of wear resistance on Cu surface removal rate increases from $285\;{\AA}/min\;to\;8645\;{\AA}/min$ in Cu CMP.

The study of accelerating method for Mobile Product with sweat resistance (Mobile 제품 도장의 내한성(耐汗性) 가속 평가법 개발)

  • Park, Kwang-Young;Lim, Sung-Gyun;Cha, Seung-Kyu
    • Journal of Applied Reliability
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    • v.6 no.3
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    • pp.205-212
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    • 2006
  • The purpose of this article is about the accelerated product-reliability-test method of the changing colors of mobile products, which are majorly from the frequent touching of sweating fingers. Such problems of changing colors of mobile products have found mostly In metallic paint containing aluminum paste pigments. Also we found that the color of Al Paste is changed by human sweat. Therefore, the accelerated experimental method has been tested as follow: applying the various concentration of lactic acid, which is the changing color components from human sweat, and deeping the testing sample under temperature of $60^{\circ}C$ in dilutelactic acid with water. From the series of tests, the most optimum concentration of lacticacid has been obtained in 10wt% and the sample is observed to be almost same effect as natural changing of colors by human touching after the test. It has been also confirmed from the cross-sectional analysis. In detail, the testing sample has changed its color in 48hr by changing color effect of Alpaste with 10 wt% of lactic acid, and the digit of $\Delta$ E has measured 10.9 after the test.

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Studies on Bonding Characteristics of Plywood by Kraft Black Liquor and Surface Activators (크라프트펄프 폐액(廢液)과 표면산화제(表面酸化劑)를 이용(利用)한 합판(合板)의 접착특성(接着特性)에 관(關)한 연구(硏究))

  • Chung, In-Ju;Lee, Phil-Woo
    • Journal of the Korean Wood Science and Technology
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    • v.16 no.3
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    • pp.5-16
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    • 1988
  • This experiment was executed to investigate the effect of activation of veneer surface by oxidizing agents, hydrogen peroxide and nitric acid, on bonding characteristics of Malas(Homalium foetidum Benth) plywood, in which the effects of these oxidizing agents amount, pretreatment time, and pressing time and temperatue on shear strength of the plywood were examined and discussed. In this research the activation of veneer surface by oxidants was effective in raising shear strength but the difference in shear strength was not observed between hydrogen peroxide and nitric acid treatment. Hydrogen peroxide treatment, however, seemed to be more profitable to industrial application because of its lower concentration and easier handling than nitric acid. The bonding method by lignin-phenol adhesive through surface activation revealed inferior shear strength to phenol- and urea-formaldehyde adhesive but superior water resistance to urea-formaldehyde adhesive and this bonding method, in addition, have the advantage of lower cost compared with phenol-formaldehyde adhesive, Therefore, this bonding method by lignin-phenol adhesive through surface activation seemed to economical in manufacturing of water-resistant wood panel materials in future.

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Evaluation of Lactic Acid Bacteria for the Resistance to Endocrine Disruptors

  • Kim, Su-Won;Min, Byung-Tae;Yoo, Min
    • Biomedical Science Letters
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    • v.8 no.2
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    • pp.95-99
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    • 2002
  • Endocrine disruptors are chemicals which can be found in our normal daily life. They can be easily ingested through plastic food containers, pesticides, etc. They include DDT, bisphenol A, benzophenone and phenylphenol, etc. Endocrine disruptor can be very harmful and toxic because it disrupts the normal function of the endogenous endocrine system. It has been reported that endocrine disruptor can cause the fatal strike in reproductive system central nervous system and the other part of the body. We have examined if the growth of lactic acid bacteria could be resistant to the endocrine disruptor. We have used Lactobacillus delbruekii as an experimental strain and benzophenone and phenylphenol for the comparison purpose. Experiments included the evaluation of turbidity, absorbance and actual cell counts. Although Lactobacillus delbruekii showed the higher resistance to benzophenone than phenylphenol it was still resistant to both benzophenone and phenylphenol. Because the experimental concentrations of benzophenone and phenylphenol were so high to compare with the actual concentration we meet in daily life, Lactobacillus delbruekii was considered to be sufficient to survive in the environmental concentration of these endocrine disruptors. This study should contribute to the development of fermented beverage with beneficial effect by lactic acid bacteria.

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Screening and Characterization of Pro biotic Lactic Acid Bacteria Isolated from Korean Fermented Foods

  • Lim, Sung-Mee;Im, Dong-Soon
    • Journal of Microbiology and Biotechnology
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    • v.19 no.2
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    • pp.178-186
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    • 2009
  • To examine their potential as probiotics, acid and bile tolerance, antibiotics resistance, adhesion capacity to Caco-2 and HT-29, and antibacterial activity, of LAB isolated from Korean fermented foods such. as dongchimi, kimchi, Meju, and doenjang were assayed against foodborne pathogenic bacteria. DC 55, DC 136, DC 222, KC 21, KC 24, KC 34, KC 43, KC 117, MJ 54, MJ 301, SP 33, and SP 170 strains were resistant to acid and bile conditions. In particular, DC 55, DC 136, KC 24, KC 43, and MJ 301 strains were highly resistant to higher than 20 ${\mu}g/ml$ concentrations of vancomycin, streptomycin sulfate, or amoxicillin, whereas, DC 222, KC 21, KC 34, KC 117, MJ 54, and SP 33 strains were susceptible to lower than 2 ${\mu}g/ml$ concentrations of those antibiotics. The adhesion to HT-29 and Caco-2 cells varied with the strains tested in a strain-dependent manner. The highest level of adhesion was observed with DC 55, KC 21, KC 24, and MJ 301 strains, having higher than 50% of adhesion to HT-29 or Caco-2 cells. In addition, Staphylococcus aureus was the most sensitive to KC 21, showing an inhibition of about 70%, and the antibacterial activity of KC 21 against S. aureus resulted most likely from both organic acids and bacteriocin. Based on its phenotypic characteristics and utilization of various sugars, the KC 21 strain was identified as Lactobacillus plantarum.

Antibacterial Activity of Fermented Korean Medicine Against Multi-drug Resistant Pseudomonas aeruginosa (발효한약의 항생제 다제내성균 Pseudomonas aeruginosa를 억제하는 항균활성)

  • Ryu, Ji-Yeon;Park, Young-Ja;Kim, Hyun-Soo
    • KSBB Journal
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    • v.26 no.6
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    • pp.543-551
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    • 2011
  • Bacterial antibiotic resistance is a real and growing problem for both Gram positive and Gram negative bacterial pathogens in the hospital setting. Among Gram negative bacteria, the ubiquitous bacterium Pseudomonas aeruginosa is a particular concern in immunocompromised and burn patients. The present study evaluated antibacterial activity and efficacy of a Korean herbal medicine against eight multi-drug resistant clinical isolates of P. aeruginosa (0225, 0254, 0347, 0826, 1113, 1378, 1731, and 2492) isolated at Daegu Catholic University Hospital. Methanol extracts of Galla rhois (5 and 10 mg/mL) displayed inhibition diameters for isolate 2492 of 10 and 12 mm, respectively, in a conventional disc diffusion assay. In seven kinds of Korean herbal medicines, increased inhibitory power of Lonicera japonica, Gardenia jasminoides, Galla rhois, and Scultellaria baicalensis was evident with the fermentation of six kinds of lactic acid bacteria. Three lactic acid bacteria (Lactobacillus plantarum subsp. plantarum KCTC 3108, L. casei KCTC 3109, and L. fermentum KCTC 3112) were identified as excellent strains for the production of antibacterial materials. In the six Korean herbal medicine extracts, strong inhibitory activity of fermented Forsythia suspensa, Glycyrrhizae radix, Lycium chinense, Platycodon grum, and Schizandra chinensis with five kinds of lactic acid bacteria was evident for seven multi-drug resistant P. aeruginosa isolates.