• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.3 no.3
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• pp.139-148
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• 2022

Saxifraga hirculus is classified as a vulnerable plant species in Europe, and it is confined to base-rich flushes in the British uplands. However, a lack of available information about its conservation status hampers the development of adaptive strategies for its in-situ conservation, especially with respect to grazing. To assess the effectiveness of sheep grazing in maintaining viable populations of S. hirculus, we compared the community dynamics of the vegetation in a base-rich flush over 44 years in two plots: one sheep-grazed under business-as-usual sheep grazing densities and the other fenced to exclude grazing. The plots were established in 1972, and the abundances of all vascular plants, bryophytes, and litter were measured at six intervals until 2016. Our results showed that although the presence of S. hirculus was maintained in both plots over the 44 years, it declined and reached a minimum between 1995 and 2010, when it was close to extinction. Since 2013, Saxifraga has recovered only slightly. Interestingly, the S. hirculus response appeared to be independent of grazing treatment, but it mirrored wider changes in the vegetation composition and structure within the flush over the 44 years. These changes are similar to others reported in broader uplands that have been attributed to a combination of reduced nitrogen and sulfur deposition and global warming. Thus, the simple adaptive management approach of "just managing" sheep grazing appeared ineffectual for preserving the S. hirculus population. S. hirculus showed signs of recovery at the end of the study period within this base-rich flush.

• Composites Research
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• v.29 no.4
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• pp.132-137
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• 2016

Based on mussel-inspired polydopamine (PDA), a novel technique to fabricate carbon nanowire (CNW) arrays is presented for a possible use of porous carbon electrode in electrochemical energy storage applications. PDA can give more porosity and nitrogen-doping effect to carbon electrodes, since it has high graphitic carbon yield characteristic and rich amine functionalities. Using such outstanding properties, the applicability of PDA for electrochemical energy storage devices was investigated. To achieve this, the decoration of the CNW arrays on carbon fiber surface was performed to increase the surface area for storage of electrical charge and the chemical active sites. Here, zinc oxide (ZnO) nanowire (NW) arrays were hydrothermally grown on the carbon fiber surface and then, PDA was coated on ZnO NWs. Finally, high temperature annealing was performed to carbonize PDA coating layers. For higher energy density, manganese oxide ($MnO_x$) nanoparticles (NPs), were deposited on the carbonized PDA NW arrays. The enlarged surface area induced by carbon nanowire arrays led to a 4.7-fold enhancement in areal capacitance compared to that of bare carbon fibers. The capacitance of nanowire-decorated electrodes reached up to $105.7mF/cm^2$, which is 59 times higher than that of pristine carbon fibers.

• Journal of Plant Biotechnology
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• v.6 no.4
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• pp.259-264
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• 2004

The present study describes the ameliorating effect of $Ca^{++}\;on\;Cd^{++}$ toxicity on the germination, early growth of mungbean seedlings, nitrogen assimilation enzyme. s-nitrate reductase (NR), nitrite reductase (NIR), anti-oxidant enzymes (POD, CAT and SOD) and on the accumulation of hydrogen peroxide and sulphydryls. $Cd^{++}$ inhibited seed germination and root and shoot length of seedlings. While NR activity was down- regulated, the activities of NIR, POD and SOD were up- regulated with $Cd^{++}$ treatment. $Cd^{++}$ treatment also increased the accumulation of sulphydryls and peroxides, which is reflective of increased thiol rich proteins and oxidative stress. $Ca^{++}$ reversed the toxic effects of $Cd^{++}$ on germination and on early growth of seedlings as well as on the enzyme activities, which were in turn differentially inhibited with a combined treatment with calcium specific chelator EGTA. The results indicate that the external application of $Ca^{++}$ may increase the tolerance capacity of plants to environmental pollutants by both up and down regulating metabolic activities. Abbreviations: $Cd^{++}= cadmium,\;Ca^{++} = calcium$, NR= nitrate reductase, NIR=nitrite reductase, POD = peroxidse, SOD= superoxide dismutase, CAT= catalase, EGTA= ethylene glycol-bis( $\beta-aminoethyl ether$)-N,N,N,N-tetraacetic acid.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.4
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• pp.537-542
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• 2002

A study was conducted to evaluate the nutritive potential value of different aquatic plants: duckweed (Lemna trisulaca), duckweed (Lemna perpusila), azolla (Azolla pinnata) and water-hyacinth (Eichhornia crassipes) from Bangladesh. A wide variability in protein, mineral composition, gas production, microbial protein synthesis, rumen degradable nitrogen and in situ dry matter and crude protein degradability were recorded among species. Crude protein content ranged from 139 to 330 g/kg dry matter (DM). All species were relatively high in Ca, P, Na, content and very rich in K, Fe, Mg, Mn, Cu and Zn concentration. The rate of gas production was highest in azolla and lowest in water-hyacinth. A similar trend was observed with in situ DM degradability. Crude protein degradability was highest in duckweed. Microbial protein formation at 24 h incubation ranged from 38.6-47.2 mg and in vitro rumen degradable nitrogen between 31.5 and 48.4%. Based on the present findings it is concluded that aquatic species have potential as supplementary diet to livestock.

• Electrical & Electronic Materials
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• v.7 no.1
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• pp.25-31
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• 1994

Properties of oxynitride films reoxidized by $N_2{O}$ gas after thermal oxidation and $N_2{O}$ oxide films directly oxidized by using $N_2{O}$ gas on the bare silicon wafer have been studied. From the AES analysis, nitrogen pile-up at the interface of Si/oxynitride and Si/$N_2{O}$ oxide has observed. $N_2{O}$ oxide and oxynitride films have the self-limited characteristics. Therefore, it will be possible to obtain ultra-thin films. Nitrogen pile-up at the interfaces of Si/oxynitride and Si/$N_2{O}$ oxide strengthens film structure and improves dielectric reliability. Although fixed charge densities and interface trap densities of N20 oxide and oxynitride films have somewhat higher than those of thermal $SiO_2{O}$, $N_2{O}$ oxide and oxynitride films showed improved I-V characteristics and constant current stress.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.69-69
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• 2001

We report a study of the nitriding of the martensitic grade of stainless steel AKSK 420 in a low-pressure rl discharge using pure nitrogen. Much studied samples of the austenitic grade AISI 304 were treated at the same time to provide a comparison. With a treatment time of 4.0 h at $400^{\circ}C$, the nitrogen-rich layer on MSK 420 is 20pm thick and has a hardness about 4.3 times higher than that of the untreated material. The layer thickness is much greater than that obtained on AISI 304 under identical treatment conditions, reflecting the different Cr content of the two alloys. The alloy AlISI 420 is more susceptible than AISI 304 to the formation of CrN and ferrite, and this has a deleterious effect on the hardnes, gain. Below the temperature at which CrN forms, the treated layer retains its martensitic structure, but with a larger lattice parameter than the bulk, a phase that we term expanded martensite, by analogy with the situation with austenitic stainless steel. The fact that the treated layer retains a martensitic structure is interesting in view of previous evidence that nitrogen is an austenite stabilizer.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.6
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• pp.810-817
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• 2011

A feeding trial was conducted to study the effect of tannin rich Pakar (Ficus infectoria) leaves on microbial profile, rumen fermentation and nutrient utilization in goats. Eight goats divided in two groups were fed pakar leaves (experimental group) and green oats (control group) as sole roughage source along with a fixed quantity of concentrate mixture for a period of 3 months. Two metabolic trials of six days duration were conducted after 30 and 90 days of experimental feeding. The dry matter intake was significantly higher (p<0.05) and digestibility's of DM, OM, CP, EE, NDF and ADF were reduced in experimental as compared with the control group. The TDN intake was similar (236.52 vs. 240.39 g/d) in both the groups. All the animals were in positive nitrogen balance. The concentration of ammonia nitrogen, TVFA, lactic acid and activities of xylanase and protease were reduced in pakar leaves fed goats. The rumen microbial profile as obtained by MPN technique showed no change in total bacterial population but total fungi and cellulolytic bacteria were reduced (p<0.05), whereas, tannin degrading/tolerant bacteria increased with the feeding of pakar leaves. Real time PCR data revealed a decrease in Ruminococcus flavefaciens, an increase in methanogens and no change in the Fibrobacter succinogenes population by feeding of pakar leaves.

• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.2116-2124
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• 2015

To understand the effects of physicochemical factors on nitrite transformation by microalgae, a lipid-rich Chlorella with high nitrite tolerance was cultured with 8 mmol/l sodium nitrite as sole nitrogen source under different conditions. The results showed that nitrite transformation was mainly dependent on the metabolic activities of algal cells rather than oxidation of nitrite by dissolved oxygen. Light intensity, temperature, pH, NaHCO₃ concentrations, and initial cell densities had significant effects on the rate of nitrite transformation. Single-factor experiments revealed that the optimum conditions for nitrite transformation were light intensity: 300 μmol/m²/s; temperature: 30℃ pH: 7-8; NaHCO₃ concentration: 2.0 g/l; and initial cell density: 0.15 g/l; and the highest nitrite transformation rate of 1.36 mmol/l/d was achieved. There was a positive correlation between nitrite transformation rate and the growth of Chlorella. The relationship between nitrite transformation rate (mg/l/d) and biomass productivity (g/l/d) could be described by the regression equation y = 61.3x (R² = 0.9665), meaning that 61.3 mg N element was assimilated by 1.0 g dry biomass on average, which indicated that the nitrite transformation is a process of consuming nitrite as nitrogen source by Chlorella. The results demonstrated that the Chlorella suspension was able to assimilate nitrite efficiently, which implied the feasibility of using flue gas for mass production of Chlorella without preliminary removal of NO_X.

• Korean journal of food and cookery science
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• v.15 no.2
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• pp.95-101
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• 1999

This study was carried out to prepare green teas by traditional roasting manufacturing process, Ku Geung Ku Po and to determine the quality charateristics of the green teas by examining the change of their main components induced during this roasting process. The content of total sugars in unroasted tea leaves was 7.82%. Its content of roasted teas was decreased by increasing the number of roasting and there was significantly differences between samples. The content of total sugars in 9th roasted green tea was 3.98%. The total nitrogen contents of green teas produced by this process were 4.96∼6.38%. The more the number of roasting and the less content of tannin in green teas. And the ratio of total nitrogen and tannin in tea leaves 21.97 but its ratio in 9th roasted tea was increased to 45.54. The ascorbic acid in tea leaves consisted in 1,820.3 mg/100g but its content was decreased by increasing the number of roasting process. Whereas the content of caffeine in green teas was not reduced significantly by this traditional method. Of all amino acids, green tea produced by Ku Jeung Ku Po was rich glutamic acid, lysine and aspartic acid. And especially, phenylalanine, which was rarely found in other green teas, was abundant in these green teas. The compositions of glutamic acid and methionine were increased as increasing the number of roasting process but those of aspartic acid and arginine decreased by these processing. The main fatty acids of Ku Jeung Ku Po green tea were linolenic acid, linoleic acid and palmitic acid and the contents of unsaturated fatty acid in green teas were composed over 70% of total fatty acid. And the fatty acid contents in green teas were not affected during Ku Jeung Ku Po's process. The contents of minerals in these teas was rich in the oder of potassuim. magnessuim and calciumim, and these contents were not observed the prominant change during the process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.271-274
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• 2000

Gas sensor materials capable of detecting hydrogen gases (H$_2$) or nitrogen oxides (NO$\_$x/, primarily NO and NO$_2$) with high sensitivity have attracted much interest in conjunction with the growing concern to the protection of global environments. Beside conventional sensor materials, such as semiconductors., conducting polymers and solid electrolytes, the potential of sensor materials with a new method for detecting hydrogen gases or nitrogen oxides gas has also been tested. The breakdown voltage of porous varistors shifted to a low electric field upon exposure to H$_2$ gas, whereas it shifted to a reverse direction in an atmosphere containing oxidizing gases such as O$_3$ and NO$_2$ in the temperature range of 300 to 600$^{\circ}C$. Furthermore, it was found that the magnitude of the breakdown voltage shift, i. e. the magnitude of sensitivity, was well correlated with gas concentration, and that the H$_2$ sensitivity was improved by controlling the composition of the Bi$_2$O$_3$ rich grain boundary phase. However, NO$\_$x/ sensing properties of porous varistors have not been studies in detail. The objective of the present study is to investigate the effect of the composition of the Bi$_2$O$_3$ rich grain boundary phase and other additive such as A1$_2$O$_3$ on the hydrogen gases (H$_2$) sensing properties of porous ZnO based varistors.