Changes In Chemical Components Research Articles

The Effects of CO2 Laser Irradiation on Color and Major Chemical Component Changes in Hardwoods

The influence of laser radiation was evaluated relative to the color and major chemical component changes of three hardwood species. The surfaces of maple (Acer pseudoplatanus L.), beech (Fagus sylvatica L.), and lime (i.e. linden, Tilia vulgaris) wood were exposed to radiation from a CO2 laser (wavelength = 10.6 µm, output power = 45 W). It was observed that increased doses of irradiation resulted in a decrease in the lightness (L*), increase in the total color difference, and a drop in the total polysaccharide content. Compared with the non-irradiated specimens, the ΔL* values at the highest irradiation doses were −56 (maple), −46.8 (beech), and −50.5 (lime). The trends observed in the FTIR spectra also showed there was a relationship between the breaking of C=O and C=C bonds in important functional groups in the lignin, hemicellulose, and carbohydrates. A highly linear correlation (R2 from 0.902 to 0.987) was observed between the increase in the ΔL* and decrease in the hemicellulose content, which degrades faster than other basic wood components. Such a phenomenon may have been related to the formation of new chromophore structures, which caused the color changes in the wood.

Decay-like fracture mechanism of silicone rubber composite insulator

In recent years, a new kind of abnormal fracture phenomena of composite insulator occurred in high voltage transmission lines in several countries, which was totally different from brittle fracture and normal fracture. According to the general characteristic features of the fracture, this type of failure was named decay-like fracture of composite insulator by the author. In this paper, a decay-like fractured composite insulator was investigated and microscopic physic-chemical properties of decay-like fractured Fiber Reinforced Plastic (FRP) core rod were analyzed. Scanning Electron Microscope (SEM), Thermal Gravimetric Analysis (TGA) and Fourier Transform Infrared (FTIR) Spectroscopy methods were employed to explain the microscopic morphology characteristics and chemical component changes of decay-like fractured composite insulator, and to further explain the reasons for the name of decay-like fracture in terms of crisp and decay-like. The main microscopic feature of decay-like fracture is the degradation and deterioration of the epoxy resin matrix in FRP rod. The mechanism of decay-like fracture of composite insulator could be summarized as follows. Due to the liquids penetration into the sheath-core interface, hydrolysis of silane coupling agent with bad quality leads to poor adhesion strength and interface voids, which results in distortion of electric field at the sheath-core interface. Under the combined action of damp condition and high electric field, discharge and current appear along the FRP rod surface. Epoxy resin matrix is eroded in the presence of discharge and current, and then is soften, melt, evaporated. Meanwhile, ion-exchange and hydrolysis process happen between glass fibers under the combined action of mechanical stress and nitric acid produced by discharge in the presence of moisture. Fiber-resin interface in FRP rod is separated owing to the erosion of epoxy resin. The degradation direction of the decay-like fracture is from outside to inside of FRP rod, and the interface between silicone rubber sheath and FRP rod is confirmed to be the initial deterioration area of the decay-like fracture. The criterion to distinguish the differences between the decay-like fracture, brittle fracture and normal fracture depends on whether the epoxy resin matrix is degraded and deteriorated or not.

DRAGON FRUIT JUICE ADDITION IN PALM OIL-PUMPKIN EMULSION: PANELIST ACCEPTANCE AND ANTIOXIDANT CAPACITY

Addition of dragon juice to emulsion products formulated from olein fraction of red palm oil and pumpkin juice was conducted as an effort to improve the taste thus it can be accepted by consumers. This study aims to (1) observe the acceptance of 60 panelists aged 17-21 years on the parameters of taste, aroma, mouthfeel, color, flavor and aroma of each contributing components of dragon fruit, palm oil, and raspberry flavor with the addition of dragon fruit juice at level 0 (control), 25, 50, and 75% (v/v), and (2) observe the changes in chemical components i.e. vitamin C and total titrable acids, total carotenoid by spectrophotometry, and antioxidant activity by 2,2-diphenyl-1-picrylhdrazyl (DPPH) reduction method. The best formula was the one containing 75% (v/v) of red dragon juice in fresh condition with vitamin C content of 19.32±0.62 mg/100 mL, antioxidant activity of 354.25±0.77 ppm, hedonic color, taste, and viscosity between favorable and very favorable. After 2 weeks of storage at room temperature (28±2oC), the vitamin C, total carotene, and antioxidant activity of the mixture decreased by 29.72, 15.44, and 46.59%, res-pectively.

Dynamic changes in amino acids, catechins, caffeine and gallic acid in green tea during withering

In order to clarify the relationship between withering process and green tea quality, dynamic changes in the major chemical components of green tea, including amino acids, catechins, caffeine (CAF) and gallic acid (GA), were investigated during withering at different times (ranging from 0 h to 21 h) and temperatures (15, 20 and 25 °C). One-way and two-way analyses of variance (ANOVA) with Duncan’s test were used to analyse the change of chemical components. Results showed that during the withering process, contents of most free amino acids increased with increasing withering time and temperature. Theanine (Thea) contents decreased slightly with fluctuations, glutamic acid (Glu) and aspartic acid (Asp) contents presented an increase–decrease pattern, whereas proline (Pro) contents remained almost constant. Total free amino acids increased up to 18 h but declined thereafter. Most catechins decreased with increasing withering time and temperature. In addition, GA contents increased with increasing time and temperature; while CAF contents increased with increasing withering time, but were only slightly correlated with withering temperature. This experiment recommended withering for 15–18 h below 25 °C to produce high quality green tea.

Investigation of plasma-enhanced-fluorination treatment on epoxy resins for high-voltage DC applications

Charge build-up under high voltage DC is a significant concern in the transmission system as its presence may distort the local electric field. By chemically treat polymeric insulation via plasma-enhanced-fluorination (PEF) treatment, the charge transport characteristics of the material can be modified. In doing so, excellent surface properties similar to those of fluoropolymers can be attained without compromising the bulk properties of the original polymeric insulation. The change in chemical components at the surface of polymeric insulation should lead to a corresponding change in dielectric properties at the surface and consequently may suppress the occurrences of charge build up. In this paper, the performance of plasma-treated epoxy resins was investigated in term of its dielectric performances, and valid comparison is made between PEF and direct-fluorination treatment from author's previous work. The tests include surface current measurement and surface flashover performances using a pair of finger electrodes. The effect of moisture absorption on the treated surface was also discussed and proved to be the limiting factor in the improvement of dielectric properties of fluorination treatment. This research proved that the introduction of the fluorinated surface layer on epoxy resins does play a major role in improving the surface dielectric properties for the use as insulation spacer in high voltage DC GIS systems.

Monitoring Chemical Changes on the Surface of Kenaf Fiber during Degumming Process Using Infrared Microspectroscopy

Degumming is the dominant method to obtain lignocellulosic fibers in the textile industry. Traditionally, wet chemistry methods are used to monitor the evolution of major chemical components during the degumming process. However, these methods lack the ability to provide spatial information for these heterogeneous materials. In this study, besides wet chemistry and scanning electron microscopy (SEM) analysis, a Fourier-transform infrared microspectroscopy (FTIRM) method was employed to monitor the changes in spatial distribution of the main chemical components on the kenaf surface during a steam explosion followed by chemical degum process. The results showed that hemicellulose and lignin were degummed at different rates, and the mechanisms of their degumming are different. The infrared microspectral images revealed the distribution changes of chemical components on the fiber bundle surface during the process, indicating that FTIRM is an effective tool to analyze the degumming process and improve degumming methods.

Effect of processing time of Polygoni Multiflori Radix on content changes of 16 componens

To study 48 h processing time of Polygoni Multiflori Radix on its contents and changes of chemical components. HPLC was used to determine the contents of various components in 22 Polygoni Multiflori Radix samples with different processing time, and then the fingerprint similarity analysis and clustering analysis were used for characteristics analysis. Results showed that the similarity was between 0.9-1.0, with good correlation between the samples. In the clustering analysis, the 22 Polygoni Multiflori Radix and processed Polygoni Multiflori Radix samples were classified into 4 types according to the composition changes. The results demonstrated that 4-5 h was the best processing time, providing references for quality control and further study of Polygoni Multiflori Radix.

Xylanase Treatment Suppresses Light- and Heat-Induced Yellowing of Pulp.

Xylanase is commonly applied in pulp and paper industries to ease cost-related and environmental pressures. The effect of xylanase treatment on pulp bleaching is well-established, however, few studies were conducted on the effects of xylanase treatment in pulp yellowing, especially the mechanism of pulp yellowing inhibition by xylanase treatment. In this study, pure xylanase (EC 3.2.1.8) was applied to treat wheat straw chemical pulp (CP) and poplar chemi-thermo-mechanical pulp (CTMP) to determine their effects on pulp brightness and on light- and heat-induced yellowing. The xylanase treatment decreased the post-color number of the pulps during light- and heat-induced yellowing. However, differences were observed in the yellowing inhibition between the wheat straw CP and poplar CTMP. The changes in chemical components of pulps after the xylanase treatment, for example, lignin, hemicellulose, and HexA contents, and analysis of UV–vis absorption spectra and Fourier transform infrared-attenuated total reflectance spectrum were used to explore the pulp yellowing inhibition causes by the xylanase treatment.

A Principal Component Analysis in Switchgrass Chemical Composition

In recent years, bioenergy has become a promising renewable energy source that can potentially reduce the greenhouse emissions and generate economic growth in rural areas. Gaining understanding and controlling biomass chemical composition contributes to an efficient biofuel generation. This paper presents a principal component analysis (PCA) that shows the influence and relevance of selected controllable factors over the chemical composition of switchgrass and, therefore, in the generation of biofuels. The study introduces the following factors: (1) storage days; (2) particle size; (3) wrap type; and (4) weight of the bale. Results show that all the aforementioned factors have an influence in the chemical composition. The number of days that bales have been stored was the most significant factor regarding changes in chemical components due to its effect over principal components 1 and 2 (PC1 and PC2, approximately 80% of the total variance). The storage days are followed by the particle size, the weight of the bale and the type of wrap utilized to enclose the bale. An increment in the number of days (from 75–150 days to 225 days) in storage decreases the percentage of carbohydrates by −1.03% while content of ash increases by 6.56%.

Impact of sulfur fumigation on quality of Scutellariae Radix

Sulfur fumigation usually causes transformation of chemical components of traditional Chinese medicine (TCM). As for the process and storage of TCM, the sulfur fumigation has been no longer recommended by the government. This study is to explore the impact of the sulfur fumigation on the quality of Scutellariae Radix. Distillation combined with ion-chromatography was used to evaluate the residue of sulfur dioxide in 180 batches of Scutellariae Radix decoction pieces and 26 batches of Scutellariae Radix herbs. In addition, LC-MS combined with principal component analysis (PCA) was used to compare the changes in chemical components and flavonoid content in radix scutellariae before and after sulfur fumigation. As a result, 74 batches of Scutellariae Radix decoction pieces were determined to be unqualified on the basis of the residue limit of sulfur dioxide in Chinese Pharmacopoeia 2015 Vol. Ⅳ (≤150 mg•kg⁻¹), with a qualification rate of 35.9%. All of the unqualified samples were decoction pieces. The fingerprint and PCA indicates that flavonoid content of Scutellariae Radix had no change before and after sulfur fumigation, but flavonoid glycosides decreased after sulfur fumigation and baicalin decreased sharply. The flavonoid glycoside was hydrolyzed to flavone aglycone in the process of sulfur fumigation, which caused the decrease in content of falvonoid glycosides and had an impact on the quality of Scutellariae Radix. The decoction pieces of Scutellariae Radix were seriously fumigated with sulfur in the processing, suggesting the key regulatory point is the decoction pieces production process.

Changes in Chemical Composition, Total Phenolics and Antioxidant Activity of Alpinia (<i>Alpinia zerumbet</i>) Leaves Exposed to UV

Alpinia zerumbet (Pers.) B.L. Burtt. & R.M. Sm is an important perennial ginger plant in the tropics with various uses as foods, dietary supplement, cosmetics, essential oil production and traditional medicines. In this study, essential oils, phenolic acids, fatty acids, kavains, total phenols and antioxidant activity in A. zerumbet plants exposed to UV-C were investigated. Number and weights of essential oils increased rapidly from 1 to 3 days of exposure. Major extend of essential oils was recorded in methyl cinnamate and followed by benzyl acetone. The correspondence to the accumulation of palmitic acid was 15 folds, in contrast to the strong reduction of stearic quantity was 10 folds at 3 days of treatment. Changes in chemical components and antioxidant capacity in A. zerumbet are differed reversely between the exposure of UV-C and heavy toxic chemicals. The exposure of UV-C is beneficial for the increasing of essential oil production in A. zerumbet.

Changes in Chemical Composition, Total Phenolics and Antioxidant Activity of Alpinia (<i>Alpinia zerumbet</i>) Leaves Exposed to UV

Alpinia zerumbet (Pers.) B.L. Burtt. & R.M. Sm is an important perennial ginger plant in the tropics with various uses as foods, dietary supplement, cosmetics, essential oil production and traditional medicines. In this study, essential oils, phenolic acids, fatty acids, kavains, total phenols and antioxidant activity in A. zerumbet plants exposed to UV-C were investigated. Number and weights of essential oils increased rapidly from 1 to 3 days of exposure. Major extend of essential oils was recorded in methyl cinnamate and followed by benzyl acetone. The correspondence to the accumulation of palmitic acid was 15 folds, in contrast to the strong reduction of stearic quantity was 10 folds at 3 days of treatment. Changes in chemical components and antioxidant capacity in A. zerumbet are differed reversely between the exposure of UV-C and heavy toxic chemicals. The exposure of UV-C is beneficial for the increasing of essential oil production in A. zerumbet.

Changes of specific chromatograms and contents of five components in Yinqiao powder decoctions during decocting process

To establish a method for the determination of chemical specific chromatograms and five components in Yinqiao powder decoction, and provide basis for elucidating the scientific connotation of ″taking in when the fragrance volatilized fiercely″. Yinqiao powder decoctions with different decocting times were prepared to study the changes of chemical components during decocting process. Specific chromatograms and contents of chlorogenic acid, phillyrin, arctiin, liquiritin and glycyrrhizin were determined by high performance liquid chromatography. According to the results, the similarities of Yinqiao powder decoctions with different decocting times were high, which indicated that their chemical compositions were similar. The dissolutions of the five components in Yinqiao powder reached more than 39.7% of 2 hour maximum dissolution amounts (MDA) after 20 minutes of soaking, more than 69.5% of MDA when boiling, more than 79.1% of MDA at the 5th minute after boiling, and more than 85.7% of MDA at the 10th minute after boiling. The concentrations of five components were not increasing obviously after 15 minutes of boiling (RSD<4.3%). The fragrance volatilized fiercely at about the 5th minute after boiling, which indicated that the contents of volatile components in Yinqiao powder decoctions were high, but it became weak after boiling for 15 minutes, which indicated that the contents of volatile components in Yinqiao powder decoctions were low. The results showed that the contents of five components in Yinqiao powder decoctions were heavily influenced by the decocting time. When boiling for about 5 minutes, the fragrance volatilized fiercely, both the contents of volatile components and non-volatile components were high. It is suggested that the traditional decocting method has a certain scientific basis.

Decomposition of Mongolian pine litter in the presence of understory species in semi-arid northeast China

The effects of understory plant litter on dominant tree litter decomposition are not well documented especially in semi-arid forests. In this study, we used a microcosm experiment to examine the effects of two understory species (Artemisia scoparia and Setaria viridis) litter on the mass loss and N release of Mongolian pine (Pinus sylvestris var. mongolica) litter in Keerqin Sandy Lands, northeast China, and identified the influencing mechanism from the chemical quality of decomposing litter. Four litter combinations were set up: one monoculture of Mongolian pine and three mixtures of Mongolian pine and one or two understory species in equal mass proportions of each species. Total C, total N, lignin, cellulose and polyphenol concentrations, and mass loss of pine litter were analyzed at days 84 and 182 of incubation. The chemistry of pine litter not only changed with the stages of decomposition, but was also strongly influenced by the presence of understory species during decomposition. Both understory species promoted mass loss of pine litter at 84 days, while only the simultaneous presence of two understory species promoted mass loss of pine litter at 182 days. Mass loss of pine litter was negatively correlated with initial ratios of C/N, lignin/N and polyphenol/N of litter combinations during the entire incubation period; at 182 days it was negatively correlated with polyphenol concentration and ratios of C/N and polyphenol/N of litter combinations at 84 days of incubation. Nitrogen release of pine litter was promoted in the presence of understory species. Nitrogen release at 84 days was negatively correlated with initial N concentration; at 182 days it was negatively correlated with initial polyphenol concentration of litter combinations and positively correlated with lignin concentration of litter combinations at 84 days of incubation. Our results suggest that the presence of understory species causes substantial changes in chemical components of pine litter that can exert strong influences on subsequent decomposition of pine litter.

Changes in chemical components of aerosol particles in different haze regions in China from 2006 to 2013 and contribution of meteorological factors

Abstract. Since there have been individual reports of persistent haze–fog events in January 2013 in central-eastern China, questions on factors causing the drastic differences in changes in 2013 from changes in adjacent years have been raised. Changes in major chemical components of aerosol particles over the years also remain unclear. The extent of meteorological factors contributing to such changes is yet to be determined. The study intends to present the changes in daily based major water-soluble constituents, carbonaceous species, and mineral aerosol in PM10 at 13 stations within different haze regions in China from 2006 to 2013, which are associated with specific meteorological conditions that are highly related to aerosol pollution (parameterized as an index called Parameter Linking Aerosol Pollution and Meteorological Elements – PLAM). No obvious changes were found in annual mean concentrations of these various chemical components and PM10 in 2013, relative to 2012. By contrast, wintertime mass of these components was quite different. In Hua Bei Plain (HBP), sulfate, organic carbon (OC), nitrate, ammonium, element carbon (EC), and mineral dust concentrations in winter were approximately 43, 55, 28, 23, 21, and 130 μg m−3, respectively; these masses were approximately 2 to 4 times higher than those in background mass, which also exhibited a decline during 2006 to 2010 and then a rise till 2013. The mass of these concentrations and PM10, except minerals, respectively, increased by approximately 28 to 117 % and 25 % in January 2013 compared with that in January 2012. Thus, persistent haze–fog events occurred in January 2013, and approximately 60 % of this increase in component concentrations from 2012 to 2013 can be attributed to severe meteorological conditions in the winter of 2013. In the Yangtze River Delta (YRD) area, winter masses of these components, unlike HBP, have not significantly increase since 2010; PLAM were also maintained at a similar level without significant changes. In the Pearl River Delta (PRD) area, the regional background concentrations of the major chemical components were similar to those in the YRD, accounting for approximately 60–80 % of those in HBP. Since 2010, a decline has been found for winter concentrations, which can be partially attributable to persistently improving meteorological conditions and emission cutting with an emphasis on coal combustion in this area. In addition to the scattered and centralized coal combustion for heating, burning biomass fuels contributed to the large increase in concentrations of carbonaceous aerosol in major haze regions in winter, except in the PRD. No obvious changes were found for the proportions of each chemical components of PM10 from 2006 to 2013. Among all of the emissions recorded in chemical compositions in 2013, coal combustion was still the largest anthropogenic source of aerosol pollution in various areas in China, with a higher sulfate proportion of PM10 in most areas of China, and OC was normally ranked third. PM10 concentrations increased by approximately 25 % in January of 2013 relative to 2012, which caused persistent haze–fog events in HBP; emissions also reduced by approximately 35 % in Beijing and its vicinity (BIV) in late autumn of 2014, thereby producing the Asia Pacific Economic Cooperation (APEC) blue (extremely good air quality); thus, one can expect that the persistent haze–fog events would be reduced significantly in the BIV, if approx. one-third of the 2013 winter emissions were reduced, which can also be viewed as the upper limit of atmospheric aerosol pollution capacity in this area.

Significant concentration changes of chemical components of PM1 in the Yangtze River Delta area of China and the implications for the formation mechanism of heavy haze–fog pollution

Since the winter season of 2013, a number of persistent haze–fog events have occurred in central-eastern China. Continuous measurements of the chemical and physical properties of PM1 at a regional background station in the Yangtze River Delta area of China from 16 Nov. to 18 Dec., 2013 revealed several haze–fog events, among which a heavy haze–fog event occurred between 6 Dec. and 8 Dec. The mean concentration of PM1 was 212μgm−3 in the heavy haze–fog period, which was about 10 times higher than on clean days and featured a peak mass concentration that reached 298μgm−3. Organics were the largest contributor to the dramatic rise of PM1 on heavy haze–fog days (average mass concentration of 86μgm−3), followed by nitrate (58μgm−3), sulfate (35μgm−3), ammonium (29μgm−3), and chloride (4.0μgm−3). Nitrate exhibited the largest increase (~20 factors), associated with a significant increase in NOx. This was mainly attributable to increased coal combustion emissions, relative to motor vehicle emissions, and was caused by short-distance pollutant transport within surrounding areas. Low-volatility oxidized organic aerosols (OA) (LV-OOA) and biomass-burning OA (BBOA) also increased sharply on heavy haze–fog days, exhibiting an enhanced oxidation capacity of the atmosphere and increased emissions from biomass burning. The strengthening of the oxidation capacity during the heavy pollution episode, along with lower solar radiation, was probably due to increased biomass burning, which were important precursors of O3. The prevailing meteorological conditions, including low wind and high relative humidity, and short distance transported gaseous and particulate matter surrounding of the sampling site, coincided with the increased pollutant concentrations mainly from biomass-burning mentioned above to cause the persistent haze–fog event in the YRD area.

Efficiency of a closed-coupled solar pasteurization system in treating roof harvested rainwater

Many studies have concluded that roof harvested rainwater is susceptible to chemical and microbial contamination. The aim of the study was thus to conduct a preliminary investigation into the efficiency of a closed-coupled solar pasteurization system in reducing the microbiological load in harvested rainwater and to determine the change in chemical components after pasteurization. The temperature of the pasteurized tank water samples collected ranged from 55 to 57°C, 64 to 66°C, 72 to 74°C, 78 to 81°C and 90 to 91°C. Cations analyzed were within drinking water guidelines, with the exception of iron [195.59μg/L (55°C)–170.1μg/L (91°C)], aluminum [130.98μg/L (78°C)], lead [12.81μg/L (55°C)–13.2μg/L (91°C)] and nickel [46.43μg/L (55°C)–32.82μg/L (78°C)], which were detected at levels above the respective guidelines in the pasteurized tank water samples. Indicator bacteria including, heterotrophic bacteria, Escherichia coli and total coliforms were reduced to below the detection limit at pasteurization temperatures of 72°C and above. However, with the use of molecular techniques Yersinia spp., Legionella spp. and Pseudomonas spp. were detected in tank water samples pasteurized at temperatures greater than 72°C. The viability of the bacteria detected in this study at the higher temperature ranges should thus be assessed before pasteurized harvested rainwater is used as a potable water source. In addition, it is recommended that the storage tank of the pasteurization system be constructed from an alternative material, other than stainless steel, in order for a closed-coupled pasteurization system to be implemented and produce large quantities of potable water from roof harvested rainwater.

Surface fluorinated epoxy resin for high voltage DC application

Charge accumulation under high voltage DC is a major concern in the transmission system as its presence distorts the local electric field. By performing chemical treatment on polymeric insulation via fluorination process, the charge transport characteristics of the material can be modified. In doing so, excellent surface properties of fluoropolymers can be attained without compromising the bulk properties of the original polymeric insulation. The change in chemical components at the surface of polymeric insulation should lead to a corresponding change in electrical properties at the surface and so suppress charge accumulation. In this paper, epoxy resin samples were formulated and treated with various surface fluorinating conditions. The samples then were characterised by scanning electron microscope (SEM), Raman spectroscopy and DC surface conductivity measurements. The surface potential decay measurement was performed and the result shows that there is a significant change in surface potential decay measurement with the introduction of surface fluorinated layer. The pulsed electroacoustic (PEA) measurement was used to further explain the decay mechanisms responsible for the observed phenomena. Surface DC flashover test using a pair of finger electrodes had also been conducted. It has been found that the introduction of fluorinated surface layer on epoxy resins plays an important role in improving the surface dielectric properties as apparent from the experimental results.

Changes in chemical components and cytotoxicity at different maturity stages of Pleurotus eryngii fruiting body.

The present study investigated the changes of the chemical components and cytotoxicity potency at 5 developmental stages of Pleurotus eryngii fruiting body. The carbohydrate and protein contents increased along the maturity of fruiting body while fat content decreased. By comparison, the polysaccharide-protein fractions had the highest antiproliferative effect on SGC-7901 and HepG-2 cells in vitro and increasing activity with growing maturity of P. eryngii fruiting body.The maturation process increased the protein content and acid property through the enhanced relative abundance of Asp, Thr, and Glu in polysaccharide-protein fractions. Further purification and electrophoresis identified that the polysaccharide-protein PEG-1with three subunits possibly was the target cytotoxical component. Our findings proved that mature fruiting body of P. eryngii containing these polysaccharide-proteins possessed highly nutritional values and therapeutical benefits.

Effect of direct fluorination on surface partial discharge characteristics of polyimide films

Surface charge accumulation induced by partial discharge has a great effect on breakdown characteristics of polymer insulation. By changing the chemical component in the surface layer of insulation material, fluorination will cause the corresponding change in electrical property. This paper presents a study aimed at clarifying the effect of fluorination time on the partial discharge of fluorinated polyimide (PI) film. PI samples were fluorinated in a reaction kettle at about 328 K (55 °C) using a F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> blend with volume fraction of 20% nitrogen and 0.05 MPa (500 mbar) for respectively 15, 30, 45, 60 and 90 min. The partial discharge experiment was tested at room temperature with the relative humidity of ~ 40%. A wideband detection system and a video recorder were employed to detect the partial discharge current and record discharge images in a shielding darkroom. Obtained results show that the conductivity of polyimide film becomes large after the fluorination. The corona resistance time increases with the fluorination time increases from 0 to 45 min, while it decreases when the fluorination time increases from 45 to 90 min. Recurrent plot (RP) analysis of discharge current shows that the change of chemical component in surface layer of polyimide film by fluorination makes the partial discharge become more stable and regular.