• Clean Technology
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• v.20 no.1
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• pp.42-50
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• 2014

In this study, the $Mg(OH)_2$ slurry was made form ferro-nickel slag and then used for $CO_2$ sequestration. The experiments were in the order as leaching step, precipitation, carbonation experiments. According to the leaching results, the optimal leaching conditions were $H_2SO_4$ concentration of 1 M and the temperature of 333 K. In the $Mg(OH)_2$ manufacturing step, NaOH was added to increase the pH upto 8, the first precipitation was confirmed as $Fe_2O_3$. After removal the first precipitation, the pH was upto 11, the $Mg(OH)_2$ was generated by XRD analysis. The $Mg(OH)_2$ slurry was used for $CO_2$ sequestration. The pseudo-second-order carbonation model was used to apply for $CO_2$ sequestration. The $CO_2$ sequestration rate was increased by the $CO_2$ partial pressure and temperature. However, $CO_2$ sequestration rate was decreased when temperature upto 323 K. After $CO_2$ sequestrated by $Mg(OH)_2$, the $CO_2$ can be sequestrated stable as $MgCO_3$. This study also presented optimal sequestration condition was the pH upto 8.38, the maximum $MgCO_3$ can be generated. This study can be used as the basic material for $CO_2$ sequestration by ferro-nickel slag at pilot scale in the future.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.4
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• pp.275-286
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• 2008

In this study, we investigated the anti-oxidative, anti-wrinkle and whitening effects of Platycarya strobilacea bark extracts. The free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activity ($FSC_{50}$) of extract / fractions of Platycarya strobilacea was in the order: 50% ethanol extract ($6.75{\mu}g/mL$) < deglycosylated aglycone fraction ($6.62{\mu}g/mL$) < ethyl acetate fraction ($4.15{\mu}g/mL$). Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of some Platycarya strobilacea extracts on ROS generated in $Fe^{3+}$-EDTA/$H_2O_2$ system were investigated using the luminol-dependent chemiluminescence assay. The order of ROS scavenging activity was ethyl acetate fraction (OSC50, $0.56{\mu}g/mL$) < 50% ethanol extract ($0.02{\mu}g/mL$) < deglycosylated aglycone fraction ($0.01{\mu}g/mL$). The deglycosylated aglycone fraction showed the most prominent scavenging activity. The protective effects of extract / fractions of Platycarya strobilacea on the rose-bengal sensitized photohemolysis of human erythrocytes were investigated. The ethanol extract (50%) suppressed photohemolysis in a concentration dependent manner, particularly ethyl acetate fraction exhibited the most prominent cellular protective effect (${\tau}_{50}$, 717.27 min at $10{\mu}g/mL$). The inhibitory effect of Platycarya strobilacea extracts on tyrosinase were investigated to assess their whitening efficacy. Finally, their anti-elastase activities were measured to predict the anti-wrinkle efficacy in the human skin. The inhibitory effect ($IC_{50}$) on tyrosinase of some Platycarya strobilacea extracts was 50% ethanol extract ($243.98{\mu}g/mL$) < ethyl acetate fraction ($153.87{\mu}g/mL$) < deglycosylated aglycone fraction ($137.53{\mu}g/mL$). Also, The inhibitory effect of elastase ($IC_{50}$) of some Platycarya strobilacea extracts was 50% ethanol extract ($31.01{\mu}g/mL$) < ethyl acetate fraction ($14.42{\mu}g/mL$) < deglycosylated aglycone fraction ($1.48{\mu}g/mL$). The cream containing the ethyl acetate fraction of Platycarya strobilacea extracts was formulated. The skin hydration, transepidermal water loss, and the whitening effects were investigated after topical application of the cream. The skin hydration of cream containing extract was increased by $2{\sim}8%$ than the placebo cream, transepidermal water loss was decreased. The cream containing extract suppressed the melanogenesis of skin by 9.55% than the placebo cream. These results indicate that extract / fractions of Platycarya strobilacea can function as antioxidants in biological systems, particularly skin exposed to UV radiation by anti-oxidative activity and protect cellular membranes against ROS. The inhibitory effect on elastase and tyrosinase, and the increase of skin hydration and the whitening effect of the cream containing extract could be applicable to new functional cosmetics for antiaging.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.479-484
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• 2017

In this study, antioxidative activities and cellular protective effects of 70% ethanol extracts and fractions from lavender were evaluated. The scavenging activity ($FSC_{50}$) of free radical (1,1-phenyl-2-picrylhydrazyl, DPPH) was 46.6, 45.5 and $477.5{\mu}g/mL$ in the 70% ethanol extract, ethyl acetate fraction and aglycone fraction, respectively. The reactive oxygen species scavenging activities (${OSC_{50}$) of 70% ethanol extract, ethyl acetate fraction and aglycone fraction were 8.1, 3.3 and $17.6{\mu}g/mL$, respectively, and they showed lower antioxidative activity than that of using L-ascorbic acid ($1.5{\mu}g/mL$). However, the aglycone fraction showed higher photohemolysis protective effect than that of using the 70% ethanol extract and ethyl acetate fraction. At $50{\mu}M$ concentration, the cellular protective effect (${\tau}_{50}$) of 70% ethanol extract, ethyl acetate fraction and aglycone fraction from lavender was 70.6, 87.2 and 165.2 min, respectively. In particular, the lavender aglycone fraction showed 3.8 times higher cellular protective effect than that of (+)-${\alpha}$-tocopherol. The lavender fractional components including luteolin 7-O-glucuronide, vitextin, rosmarinic acid, luteolin, and apigenin were identified using TLC and LC-MS. However, the lavender aglycone fraction did not show any significant increase in flavonoids (luteolin and apigenin) compared to that of the ethyl acetate fraction. In conclusion, it is suggested that lavender may be applied as an antioxidant material in cosmetic industries.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.37 no.4
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• pp.309-318
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• 2011

In this study, the antioxidative effect, antibacterial, inhibitory effects on tyrosinase, inhibitory effects on elastase and component analysis of Phellinus linteus (P. linteus) extracts were investigated. The ethyl acetate fraction of P. linteus extracts ($2.94\;{\mu}g/mL$) showed the highest free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activity ($FSC_{50}$). Reactive oxygen species (ROS) scavenging activity ($OSC_{50}$) of P. linteus extracts on ROS generated in $Fe^{3+}$-EDTA/$H_2O_2$ system was investigated using the luminol-dependent chemiluminescence assay. The ethyl acetate fraction ($0.0072\;{\mu}g/mL$) showed the most prominent ROS scavenging activity. The protective effects of extract/fractions of P. linteus extracts on the rose-bengal sensitized photohemolysis of human erythrocytes were investigated. The P. linteus extracts showed cellular membrane protective effects in a concentration dependent manner ($5{\sim}50\;{\mu}g/mL$). The inhibitory effect ($IC_{50}$) on tyrosinase of P. linteus extract was the highest at 50 % ethanol extract ($6.34\;{\mu}g/mL$), and the inhibitory effect ($IC_{50}$) on elastase of P. linteus was the highest at ethyl acetate fraction ($14.08\;{\mu}g/mL$). TLC, HPLC chromatogram and LC/ESI-MS of the ethyl acetate fraction obtained from P. linteus extracts were identified interfungin A (PL RPT-1a). These results indicate that extract/fractions of P. linteus can function as antioxidants in biological systems, particularly skin exposed to UV radiation by scavenging ROS, and protect cellular membranes against ROS. Extract/fractions of P. linteus can be applicable to new cosmeceuticals for antioxidant, antiaging, antiwrinkle and whitening.

• Journal of Environmental Health Sciences
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• v.31 no.5 s.86
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• pp.349-359
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• 2005

In this study, we focused on the geographical and the meterological conditions, the atmospheric examination, the soil contents and compositions in order to establish cultural properties conservation plan in Gyeongju and its surroundings. Also, the transport route with environmental contaminants in Ulsan and Pohang was examined. The results could be summarized as follows ; Air pollutant and environmental contaminant was transported by two types of winds. One is induced by local winds, the other is induced by synoptic winds. Air contaminant transported from coastal regions to inland regions were associated with wind velocity. Gyeongju had good atmospheric conditions, i.e. $SO_2\;0.009{\sim}0.011ppm,\;CO\;0.6{\sim}0.8ppm,\;NO_2\;0.015{\sim}0.020ppm,\;O_3\;0.017{\sim}0.032ppm,\;PM_{10}\;46{\sim}62{\mu}g/m^3\;and\;Pb\;0.034{\sim}0.060{\mu}g/m^3$, which was below environmental air qualify standards and was little lower than those of Pohang and Ulsan. However, Ulsan and Pohang city are located on south-east coast and have many industrial facilities. Hence, air pollution problems become serious issues in Ulsan, Pohang, Busan, Daegu and other cities due to the emission of air pollutants from the various industrial facilities, incinerator and power plants, etc. The soil of Gyeongju had heavy metals conditions, i.e. $Cd\;0.01{\sim}0.08mg/kg,\;Cu\;N.D{\sim}2.39mg/kg,\;As\;N.D{\sim}0.07mg/kg,\;Hg\;N.D{\sim}0.15mg/kg,\;Pb\;0.49{\sim}1.39mg/kg,\;Cr^{+6}\;0.02{\sim}0.42mg/kg,\;Fe\;0.74{\sim}1.55mg/kg,\;Mn\;0.11{\sim}0.49mg/kg\;and\;Zn\;1.11{\sim}3.56mg/kg$. However, pH value of soil had range of $4.12{\sim}7.45$. The results showed that high pH concentration of soil could occur due to air pollution diffusion and environmental contaminant transport at Ulsan and Pohang city.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.5
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• pp.399-407
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• 2009

Laser induced breakdown spectroscopy(LIBS) is an simple analysis method for directly quantifying many kinds of soil micro-elements on site using a small size of laser without pre-treatment at any property of materials(solid, liquid and gas). The purpose of this study were to find an optimum condition of the LIBS measurement including wavelengths for quantifying soil elements, to relate spectral properties to the concentration of soil elements using LIBS as a simultaneous un-breakdown quantitative analysis technology, which can be applied for the safety assessment of agricultural products and precision agriculture, and to compare the results with a standardized chemical analysis method. Soil samples classified as fine-silty, mixed, thermic Typic Hapludalf(Memphis series) from grassland and uplands in Tennessee, USA were collected, crushed, and prepared for further analysis or LIBS measurement. The samples were measured using LIBS ranged from 200 to 600 nm(0.03 nm interval) with a Nd:YAG laser at 532 nm, with a beam energy of 25 mJ per pulse, a pulse width of 5 ns, and a repetition rate of 10 Hz. The optimum wavelength(${\lambda}nm$) of LIBS for estimating soil and plant elements were 308.2 nm for Al, 428.3 nm for Ca, 247.8 nm for T-C, 438.3 nm for Fe, 766.5 nm for K, 85.2 nm for Mg, 330.2 nm for Na, 213.6 nm for P, 180.7 nm for S, 288.2 nm for Si, and 351.9 nm for Ti, respectively. Coefficients of determination($r^2$) of calibration curve using standard reference soil samples for each element from LIBS measurement were ranged from 0.863 to 0.977. In comparison with ICP-AES(Inductively coupled plasma atomic emission spectroscopy) measurement, measurement error in terms of relative standard error were calculated. Silicon dioxide(SiO2) concentration estimated from two methods showed good agreement with -3.5% of relative standard error. The relative standard errors for the other elements were high. It implies that the prediction accuracy is low which might be caused by matrix effect such as particle size and constituent of soils. It is necessary to enhance the measurement and prediction accuracy of LIBS by improving pretreatment process, standard reference soil samples, and measurement method for a reliable quantification method.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.1
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• pp.20-27
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• 1983

A series of laboratory experiment was conducted to find out the chemical composition, characterization of humic substances by physical and chemical methods and reaction of Na-pyrophosphate, $Ca(OH)_2$ and rice straw with albumin on the degradation of soil organic matter in the volcanic ask soils of the Jeju Island. Results obtained were summarized as follows: 1. The contents of organic matter, available silicon, active iron and aluminum concentration in volcanic ash the soils were remarkably higher but available phosphorous was comparatively lower than the mineral soils. In volcanic ash soil, the contents of potassium, calcium and magnessium were higher in upland soil than that of forest soil. The ratios of active $Al^{{+}{+}{+}}/Fe^{{+}{+}}$, C/P and $K/Ca^+$ Mg were apparently high in volcanic ash soils while that of $SiO_2$/O.M. was high in mineral soil. 2. The carbon/nitrogen ratio in humin, humic acid content in organic matter, and carbon contents of humin in total carbon of soil organic matter were apparently higher in the volcanic ash soils than in the mineral soils, The total nitrogen and fractions of acid or alkali soluble nitrogen were remarkably high in volcanic ash soils while mineralizable nitrogen ($NH_4$-N and $NO_3$) contents were high in mineral soils. 3. The values of K600, RF and log K were also higher in volcanic ash soils than those in mineral soils, and the absorbance in the visible range were high and color was dark in the soil of which humification was progressed Extracted humic acid from volcanic ash soil was less reactive to the oxidizing chemical reagent and was persistance to the acid or alkali hydrolysises. 4. The major oxygen-containing functional groups in humic substances of volcanic ash soils were phenolic-OH alcoholic-OH and carboxyl groups while those in mineral soil were methoxyl and carbonyl groups. 5. Absorption spectra of alkaline solution of humic acid ranged from 200 nm to maxima 500 nm. Visible spectra peaks of from humic substances in the visible region were recognized at 350, 420, 450 and 480 nm. Only one single absorbance peak was observed in the visible region at 362 nm for Heugag series and two absorbance Peak were also at 360 nm and 390 nm for Yeungrag series. 6. Evolution of carbon as $Co_2$ was increased with addition of Na-pyrophosphate in Namweon and Heugag series, and "priming effects" took place on the soil organic matter decomposition by addition of rice straw with albumin in Ido series.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.102-106
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• 2006

Magnetic nanoparticles can be used for a variety of biomedical applications. They can be used in the targeted delivery of therapeutic agents in vivo, in the hyperthermic treatment of cancers. in magnetic resonance (MR) imaging as contrast agents and in the biomagnetic separations of biomolecules. We have synthesized magnetite $(Fe_3O_4)$ nanoparticles using chemical coprecipitation technique with sodium oleate as surfactant. Nanoparticle size can be varied from 2 to 8nm by controlling the sodium oleate concentration. Magnetite phase nanoparticles could be observed from X-ray diffraction. Magnetic colloid suspensions containing particles with sodium oleate and chitosan have been prepared. Nanoparticles, both oleate-coated and chitosan-coated, have been characterized by several techniques. Atomic farce microscope (AFM) was used to image the coated nanoparticles. Magnetic hysteresis measurement were performed using a superconducting quantum interference device (SQUID) magnetometer at room temperature to investigate the magnetic properties of the magnetite nanoparticles. The SQUID measurements revealed superparamagnetism of nanoparticles.

• Economic and Environmental Geology
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• v.30 no.4
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• pp.289-301
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• 1997

The Boguk cobalt mine is located within the Cretaceous Gyeongsang Sedimentary Basin. Major ore minerals including cobalt-bearing minerals (loellingite, cobaltite, and glaucodot) and Co-bearing arsenopyrite occur together with base-metal sulfides (pyrrhotite, chalcopyrite, pyrite, sphalerite, etc.) and minor amounts of oxides (magnetite and hematite) within fracture-filling $quartz{\pm}actinolite{\pm}carbonate$ veins. These veins are developed within an epicrustal micrographic granite stock which intrudes the Konchonri Formation (mainly of shale). Radiometric date of the granite (85.98 Ma) indicates a Late Cretaceous age for granite emplacement and associated cobalt mineralization. The vein mineralogy is relatively complex and changes with time: cobalt-bearing minerals with actinolite, carbonates, and quartz gangues (stages I and II) ${\rightarrow}$ base-metal sulfides, gold, and Fe oxides with quartz gangues (stage III) ${\rightarrow}$ barren carbonates (stages IV and V). The common occurrence of high-temperature minerals (cobalt-bearing minerals, molybdenite and actinolite) with low-temperature minerals (base-metal sulfides, gold and carbonates) in veins indicates a xenothermal condition of the hydrothermal mineralization. High enrichment of Co in the granite (avg. 50.90 ppm) indicates the magmatic hydrothermal derivation of cobalt from this cooling granite stock, whereas higher amounts of Cu and Zn in the Konchonri Formation shale suggest their derivations largely from shale. The decrease in temperature of hydrothermal fluids with a concomitant increase in fugacity of oxygen with time (for cobalt deposition in stages I and II, $T=560^{\circ}C-390^{\circ}C$ and log $fO_2=$ >-32.7 to -30.7 atm at $350^{\circ}C$; for base-metal sulfide deposition in stage III, $T=380^{\circ}-345^{\circ}C$ and log $fO_2={\geq}-30.7$ atm at $350^{\circ}C$) indicates a transition of the hydrothermal system from a magmatic-water domination toward a less-evolved meteoric-water domination. Sulfur isotope data of stage II sulfide minerals evidence that early, Co-bearing hydrothermal fluids derived originally from an igneous source with a ${\delta}^{34}S_{{\Sigma}S}$ value near 3 to 5‰. The remarkable increase in ${\delta}^{34}S_{H2S}$ values of hydrothermal fluids with time from cobalt deposition in stage II (3-5‰) to base-metal sulfide deposition in stage III (up to about 20‰) also indicates the change of the hydrothermal system toward the meteoric water domination, which resulted in the leaching-out and concentration of isotopically heavier sulfur (sedimentary sulfates), base metals (Cu, Zn, etc.) and gold from surrounding sedimentary rocks during the huge, meteoric water circulation. We suggest that without the formation of the later, meteoric water circulation extensively through surrounding sedimentary rocks the Boguk cobalt deposits would be simple veins only with actinolite + quartz + cobalt-bearing minerals. Furthermore, the formation of the meteoric water circulation after the culmination of a magmatic hydrothermal system resulted in the common occurrence of high-temperature minerals with later, lower-temperature minerals, resulting in a xenothermal feature of the mineralization.

• Applied Biological Chemistry
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• v.21 no.3
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• pp.150-184
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• 1978

Nutritional characteristics and physio-chemical properties of mycelial growth and fruitbody formation of oyster mushroom(Pleurotus ostreatus)in synthetic media, the curtural condition for the commerical production in the rice straw and poplar sawdust media, and the changes of the chemical components of the media and mushroom during the cultivation were investigated. The results can be summarized as follows: 1. Among the carbon sources mannitol and sucrose gave rapid mycelial growth and rapid formation of fruit-body with higher yield, while lactose and rhamnose gave no mycelial growth. Also, citric acid, succinic acid, ethyl alcohol and glycerol gave poor fruit-body formation, and acetic acid, formic acid, fumaric acid, n-butyl alcohol, n-propyl alcohol and iso-butyl alcohol inhibited mycelial growth. 2. Among the nitrogen sources peptone gave rapid mycelial growth and rapid formation of fruit-body with higher yield, while D,L-alanine, asparatic acid, glycine and serine gave very poor fruit-body formation, and nitrite nitrogens, L-tryptophan and L-tyrosine inhibited mycelial growth. Inorganic nitrogens and amino acids added to peptone were effective for fruit-body growth, and thus addition of ammonium sulfate, ammonium tartarate, D,L-alanine and L-leucine resulted in about 10% increase fruit-body yield. L-asparic acid about 15%, L-arginine about 20%, L-glutamic acid, and L-lysine about 25%. 3. At C/N ratio of 15.23 fruit-body formation was fast, but the yield decreased, and at C/N ratio of 11.42 fruit-body formation was slow, but the yield increased. Also, at the same C/N ratio the higher the concentration of mannitol and petone, the higher yield was produced. Thus, from the view point of both yield of fruit-body and time required for fruiting the optimum C/N ratio would be 30. 46. 4. Thiamine, potassium dihydrogen phosphate and magnecium sulfate at the concentration of $50{\mu}g%$. 0.2% and 0.02-0.03%, respectively, gave excellent mycelial and fruit-body growth. Among the micronutrients ferrous sulfate, zinc sulfate and manganese sulfate showed synergetic growth promoting effect but lack of manganese resulted in a little reduction in mycelial and fruit-body growth. The optimum concentrati on of each these nutrients was 0.02mg%. 5. Cytosine and indole acetic acid at 0.2-1mg% and 0.01mg%, respectively, increased amount of mycelia, but had no effect on yield of fruit-body. The other purine and pyrimidine bases and plant hormones also had no effect on mycelial and fruit-belly yield. 6. Illumination inhibited mycelial growth, but illumination during the latter part of vegetative growth induced primordia formation. The optimum light intensity and exposure time was 100 to 500 lux and 6-12 hours per day, respectively. Higher intensity of light was injurous, and in darkness only vegetative growth without primordia formation was continued. 7. The optimum temperature for mycelial growth was $25^{\circ}C$ and for fruit-body formation 10 to $15^{\circi}C$. The optimum pH range was from 5.0 to 6.5. The most excellent fry it-body formation were produced from the mycelium grown for 7 to 10 days. The lesser the volume of media, the more rapid the formation of fruit-body; and the lower the yield of fruit-body; and the more the volume of media, the slower the formation of fruit-body, and the higher the yield of fruit-body. The primordia formation was inhibited by $CO_2$. 8. The optimum moisture content for mycelial growth was over 70% in the bottle media of rice straw and poplar sawdust. 10% addition of rice bran to the media exhibited excellent mycelial growth and fruit-body formation, and the addition of calciumcarbonate alone was effective, but the addition of calcium carbonate was ineffective in the presence of rice bran. 9. In the cultivation experiments the total yield of mushroom from the rice straw media was $14.99kg/m^2$, and from the sawdust media $6.52kg/m^2$, 90% of which was produced from the first and second cropping period. The total yield from the rice straw media was about 2.3 times as high as that from the sawdust media. 10. Among the chemical components of the media little change was observed in the content of ash on the dry weight basis, and organic matter content decreased as the cultivation progressed. Moisture content, which was about 79% at the time of spawning, decreased a little during the period of mycelial propagation, after which no change was observed. 11. During the period from spawning to the fourth cropping about 16.7% of the dry matter, about 19.3% of organic matter, and about 40% of nitrogen were lost from the rice straw media; about 7.5% of dry mallet, about 7.6% of organic matter, and about 20% of nitrogen were lost from the sawdust media. For the production of 1kg of mushroom about 232g of organic matter and about 7.0g of nitrogen were consumed from the rice straw media; about 235g of organic matter and about 6.8g of nitrogen were consumed from the sawdust media, 1㎏ of mushroom from either of media contains 82.4 and 82.3g of organic matter and 5.6 and 5.4g of nitrogen, respectively. 12. Total nitrogen content of the two media decreased gradually as the cultivation progressed, and total loss of insoluble nitrogen was greater than that of soluble nitrogen. Content of amino nitrogen continued to increase up to the third cropping time, after which it decreased. 13. In the rice straw media 28.0 and 13.8% of the total pentosan and ${\alpha}$-cellulose, respectively, lost during the whole cultivation period was lost during the period of mycelial growth; in the sawdust media 24.1 and 11.9% of the total pentosan and ${\alpha}$-cellulose, respectively, was lost during the period of mycelial growth. Lignin content in the media began to decrease slightly from the second cropping time, while the content of reduced sugar, trehalose and mannitol continued to increase. C/N ratio of the rice straw media decreased from 33.2 at spawining to 30.0 at ending; that of the sawdust media decreased from 61.3 to 60.0. 14. In both media phosphorus, potassium, manganese and zinc decreased, at magnesium, calcium and copper showed irregular changes, and iron had a tendency to be increased. 15. Enzyme activities are much higher in the rice straw media than in the sawdust media. CMC saccharifying and liquefying activity gradually increased from after mycelial propagation to the second cropping, after which it decreased in both media. Xylanase activity rapidly and greatly increased during the second cropping period rather than the first period. At the start of the third cropping period the activity decreased rapidly in the rice straw media, which was not observed in the sawdust media. Protease activity was highest after mycelial propagation, after which it gradually decreased. The pH of the rice straw media decreased from 6.3 at spawning to 5.0 after fourth cropping; that of the sawdust media decreased from 5.7 to 4.9. 16. The contents of all the components except crude fibre of the mushroom from the rice straw media were higher than those from the sawdust media. Little change was observed in the content of the components of mushroom cropped from the first to the third period, but slight decrease was noticed at the fourth cropping.