Contents Of Re Research Articles

Influence of process parameters on thickness and wear resistance of rare earth modified chromium coatings on P110 steel synthesized by pack cementation

The pack cementation was employed to produce rare earth modified chromium coatings on P110 steel aiming at improving its performance and increasing the usage lifetime during operation. The orthogonal array design (OAD) was applied to set experiments. Contents of NH 4Cl, types of RE, contents of RE, test temperature and soaking time were the main factors, and each factor was endowed with four levels. While the range analysis and analysis of variance were used to investigate the results of OAD tests on thickness and wear resistance. The results indicated that for a promising coating with higher thickness value and excellent anti-wear property, the test temperature was the most significant process factor. The potential promising conditions for chromizing treatment were: adding 1% NH 4Cl and 1% LaCl 3, maintaining the test temperature at 1000 °C for 8 h. The results of verification showed that the coating formed under the optimal process parameter had a valid thickness of 28 μm and a reduction of 0.32 mg in wear resistance test.

Effects of Re and Ru on the Solidification Characteristics of Nickel-Base Single-Crystal Superalloys

The solidification characteristics, such as the phase transformation temperature and partition coefficient, were investigated in four Ni-base single-crystal superalloys with varied contents of Re and Ru. Differential scanning calorimetry (DSC) analysis reveals that the liquidus and solidus temperatures decrease with increasing levels of Re additions. However, the Ru only has negligible influences on the liquidus and solidus temperatures. The partition coefficient of constituent elements is investigated by using the directional solidification followed quenching (DSQ) technique. Re is found to reduce the segregation of Re and W, whereas Ru only has negligible effects on the segregation of Re and W. For comparison, the matrix scanning is performed on the representative dendritic structures. With increasing withdrawal rate, Re and Ru additions show the stronger influences on segregation behavior of alloying elements, particularly for Al and Ta.

유산균 발효에 의한 인삼열매 추출물의 항산화 및 항노화 효과

The effect of lactic acid bacteria‐fermented ginseng berry extract (FGBE) on physiological activities was evaluated. The contents of ginsenosides Re, Rc, and Rb1 in ginseng berry extract (GBE) were increased after fermentation by lactic acid bacteria when analyzed by high performance liquid chromatography. Antioxidant activity of GBE and FGBE was also analyzed by DPPH radical scavenging activity assay and SOD‐like activity assay. FGBE showed a 86.34 % inhibition of DPPH radical and a 76.82 % inhibition by SOD‐like activity at a concentration of 1.00 %. GBE showed a 49.78 % inhibition of DPPH radical and a 40.80 % inhibition by SOD‐like activity at the same concentration. Furthermore, procollagen type I (COL1A1) gene expression increased by 823.13 % and matrix metalloproteinase (MMP)‐1 and tumor necrosis factor (TNF)‐α gene expression decreased by 87.88 % and 99.92 %, respectively, in human fibroblast cultured with FGBE at a concentration of 0.50 %. These results suggest that FGBE could be used as an active ingredient for functional cosmetics.

Effect of rhenium on solidification and segregation of nickel-based superalloy

The solidified process of the rhenium-containing nickel-based superalloys was investigated in this paper. The solidified experiments of samples were carried out in a silicon carbon tube furnace with following water quenching. Microstructure of samples and subsequent compositional analysis of solidified ones were determined by an optical microscope (OM) and electronic probe micro analysis (EPMA), respectively. The results show the initial temperature, final temperature and the temperature interval of solidification keep constant with increasing content of Re in alloys under the test conditions, demonstrating the similar solidification sequences. With increasing Re element in alloy, the segregation coefficient of Al, Cr, Co, Mo, and Ta slightly varies, but the segregation coefficient of W obviously decreases.

Effects of rare earth on inclusions and corrosion resistance of 10PCuRE weathering steel

The types, morphologies and distributions of nonmetallic inclusions in Cu-P weathering steels with and without rare earth were analyzed through a quantitative image analyzer, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) attached to SEM. Solid-soluble content of rare earth in the steels was analyzed by non-aqua electroanalysis and ICP. The results showed that rare earth modified the types and the morphologies of inclusions in the weathering steels. The small spherical rare earth oxysulfides and rare earth sulphides replaced the elongated MnS inclusions in the RE weathering steels. The rare earth inclusions dispersedly distributed and most inclusions were smaller than 2 μm in size. The optimum content of RE was 0.0065%-0.016% for 10PCuRE weathering steels containing about 0.002% oxygen and 0.004% sulfur. Solid-soluble content of rare earth in steels was (14-20)×10 −6, which can act as a micro-alloying element. The corrosion resistance of 10PCuRE weathering steels and Q235 were studied by dry-wet cyclic immersion test. Their corrosion rates were obtained respectively. The polarization curves and pitting corrosion behaviors of weathering steels with and without rare earth were measured by electrochemical methods. The corrosion resistance of Cu-P weathering steels was improved by adding an appropriate amount of rare earth. Less and fewer rare earth inclusions largely decreased pitting susceptibility and rate of pit propagation. The pitting potential and the resistance against pitting corrosion of the RE weathering steel were significantly improved due to the modification of rare earth to inclusions.

Dynamic response of ginsenosides in American ginseng to root fungal pathogens

The existence of a complex relationship between soil microbes and ginsenoside contents in their host plants has been reported by previous studies. Here, we analyzed the interaction between the root pathogens and the ginsenoside content in the roots of American ginseng. Two fungal pathogen species were isolated from diseased American ginseng roots, and identified as Fusarium oxysporum (isolate C1) and Fusarium solani (isolate F19) by molecular sequencing analysis. To determine the effect of Fusarium-mediated infection of American ginseng roots, the contents of three ginsenosides, ginsenosides Rb1, ginsenosides Re and ginsenosides Rg1, were monitored over a time course of 120 h post infection using high performance liquid chromatography (HPLC). We found that the level of Rb1 was rapidly upregulated upon fungal infection, whereas the contents of Re or Rg1 were not altered significantly. Furthermore, the presence of Rb1, but not Re or Rg1, significantly inhibited conidium germination of both Fusarium species. Thus, Rb1 is likely the disease-resistance compound produced by American ginseng roots in response to the pathogenic fungi. Our study is the first to report the three ginsenosides with different chemical structure respond differently to soilborne pathogen infection.

Creep properties beyond 1100 °C and microstructure of Co–Re–Cr alloys

The melting point of a novel Co–17Re–23Cr alloy (numbers given in at.%) could be increased by 250 °C as compared to established Ni-based superalloys, by optimising the content of Re. Samples were produced by vacuum arc-melting in order to evaluate the creep behaviour at temperatures beyond 1100 °C and for microstructural analysis. Three alloys (the Co–17Re–23Cr-based material, and the carbide strengthened alloys Co–17Re–23Cr–2.6C and Co–17Re–23Cr–2.6C–1.2Ta) were investigated. Creep properties, especially the minimum creep rate and the Larson–Miller plots, were compared. The Co–17Re–23Cr–2.6C–1.2Ta alloy has a higher minimum creep rate than Co–17Re–23Cr at 1200 °C but it has a lower minimum creep rate than Co–17Re–23Cr at 1100 °C. TaC coarsening, detected via transmission electron microscope (TEM) measurements may explain this effect. The overall creep behaviour of Co–17Re–23Cr–2.6C at 1200 °C is better than that of Co–17Re–23Cr–2.6C–1.2Ta, but worse than that of Co–17Re–23Cr. Microstructural investigations by scanning electron microscopy and TEM reveal a hexagonal closed-packed (hcp) matrix and σ-phases. The microhardness of the σ-phase was about 1570 HV (load: 1 g) and around 800 HV for the matrix. Pores and cracks occur along the brittle σ-phases and grain boundaries in the Co–Re–Cr alloys. A Norton exponent n in between 1.4 and 3.0 points to grain boundary dominated creep mechanisms.

The Effect of Age and Gender on 59 Trace-Element Contents in Human Rib Bone Investigated by Inductively Coupled Plasma Mass Spectrometry

The effect of age and gender on 59 trace-element contents in rib bone of 80 apparently healthy 15-55-year-old women (n = 38) and men (n = 42) was investigated by inductively coupled plasma mass spectrometry. Mean values (M ± SΕΜ) for the mass fraction (milligrams per kilogram, on dry-weight basis) of Ba, Bi, Cd, Ce, Cu, Dy, Er, Gd, La, Li, Mn, Mo, Nd, Pb, Pr, Rb, Sm, Sr, Tb, Tl, U, Yb, and Zn for both female and male taken together were: Ba 2.5 ± 0.2, Bi 0.015 ± 0.002, Cd 0.044 ± 0.005, Ce 0.029 ± 0.002, Cu 1.05 ± 0.06, Dy 0.0020 ± 0.0003, Er 0.0011 ± 0.0002, Gd 0.0015 ± 0.0001, La 0.020 ± 0.002, Li 0.040 ± 0.002, Mn 0.354 ± 0.004, Mo 0.052 ± 0.006, Nd 0.011 ± 0.001, Pb 2.24 ± 0.14, Pr 0.0032 ± 0.0004, Rb 1.51 ± 0.06, Sm 0.0014 ± 0.0001, Sr 291 ± 20, Tb 0.00041 ± 0.00005, Tl 0.00050 ± 0.00003, U 0.0013 ± 0.0001, Yb 0.00072 ± 0.00007, and Zn 92.8 ± 1.5, respectively. The upper limit of mean contents of Ag, Al, B, Be, Br, Cr, Cs, Hg, Ho, Lu, Ni, Sb, Te, Th, Ti, Tm, and Y were: Ag ≤ 0.011, Al ≤ 7.2, B ≤ 0.65, Be ≤ 0.0032, Br ≤ 3.9, Cr ≤ 0.25, Cs ≤ 0.0077, Hg ≤ 0.018, Ho ≤ 0.00053, Lu ≤ 0.00024, Ni ≤ 1.05, Sb ≤ 0.0096, Te ≤ 0.0057, Th ≤ 0.0030, Ti ≤ 2.8, Tm ≤ 0.00006, and Y ≤ 0.0047, respectively. In all bone samples, the contents of As, Au, Co, Eu, Ga, Hf, Ir, Nb, Pd, Pt, Re, Rh, Sc, Se, Sn, Ta, V, W, and Zr were under detection limits. The Ce, Dy, Er, Gd, La, Nd, Pr, Sm, Tb, and Yb contents increase with age. Higher Sr mass fraction is typical of female rib as compared to those in male bone.

Ginsenoside Composition and Antiproliferative Activities of Explosively Puffed Ginseng (Panax ginseng C.A. Meyer)

The puffing process was evaluated as an alternative to the steaming process for producing a biologically more active ginseng product, like red ginseng, from raw ginseng. A puffing treatment of dried raw ginseng roots induced an overall increase in crude saponin content. As puffing pressure increased, the content of ginsenoside Re, Rg1, Rb1, Rc, and Rb2 decreased, while ginsenoside Rg3 increased significantly as compared to raw ginseng. The content of ginsenoside Rg3 in puffed ginseng at a pressure of 490 kPa was similar to that of red ginseng. Cancer cell lines (HeLa, MCF-7, and HepG2) showed that antiproliferative effects of saponin extract of puffed ginseng increased with an increase in puffing pressure. Ginseng explosively puffed at 490 kPa had similar saponin constituents and antiproliferative effects as those of red ginseng. The puffing process could provide an alternative mean to produce functional ginseng products, along with a reduction in processing time as compared to traditional red ginseng processing by steam.

Analysis of Ginseng Saponin Content after Proton Beam Irradiation

A saponin fraction of Korean red ginseng was irradiated with a proton beam (35.7 MeV) at doses of 0.5 - 10 kGy, and the content change of several ginsenosides was investigated. LC-ESI-MS analysis of the beam-treated fraction showed that the contents of ginsenosides Rb1, Rb2, Rc, Rd or Re, and Rg3 were not appreciably changed at 0.5 - 5 kGy. However, at 10 kGy, Rg3 was nearly undetectable, and Rb1 and Rc increased about 6-fold. The peak areas of Rb2 and Rd/Re were also markedly extended at 10 kGy. The Rc and the Rd/Re contents were almost the same as they were prior to irradiation, but Rc increased much more than Rd/Re at high beam doses.

Monitoring of roasting-induced changes in ginsenoside composition of ginseng (Panax ginseng C.A. Meyer)

This study was intended to roast freeze-dried ginseng in order to determine the effect of roasting conditions on major ginsenosides by monitoring their changes using response surface methodology. As the roasting temperature and time increased, the contents of ginsenoside Re, Rg1, Rf, Rb1, Rc, Rb2, and Rd tended to decrease but that of ginsenoside Rg3 increased, reaching the maximum content (0.96 mg/g) at 189.99°C and 20.29 min as compared to the initial value (0.01 mg/g). The total ginsenoside content was estimated to be increased from 4.30 to 5.19 mg/g at 140.17°C and 27.51 min. It was found that the roasted ginseng has different ginsenoside compositions from raw ginseng. Therefore, further studies are needed to investigate the functional and biological properties of roasted ginseng as compared to the conventional white and red ginseng.

Effect of RE on Performance of Semi-Solid AlSi7 Alloy

The semi-solid slurry of AlSi7 alloy was prepared by near-liquids cast processing. The effects of different content of RE on the cast performance and the semi-solid remelting performance in AlSi7 alloy was researched. The results indicated that adding RE will widen the AlSi7 alloy solid-liquid two-phase zone temperature and refine the grains, silicon will obvious metamorphoses. The best amount of RE is about 0.5%. Its semi-solid remelting organization is equilateral globular grains.

Effects of culture conditions on biomass and active components ofadventitious roots culture in Panax ginseng

To optimize the culture condition of adventitious roots of Panax ginseng. The adventitious roots were obtained through tissue culture by manipulation of inoculum, various sucrose concentrations and salt strength. The contents of ginsenosides Re, Rb1 and Rg1 were determined by HPLC while the contents of polysaccharides were determined by ultraviolet spectrophotometry. The multiplication of adventitious roots reached the peak when the inoculum was 20 g x L(-1). The effects of sucrose concentration and salt strength on adventitious roots were observed. The contents of polysaccharides were higher when the medium contained more sucrose. 40 g x L(-1) sucrose was favorable for roots growth and biosynthesis of Re, while 30 g x L(-1) was favorable for the biosynthesis of Rb1 and Rg1. 3/4MS medium was benefit for the growth of adventitious roots and the biosynthesis of ginsenosides. The contents of polysaccharides were decreased with the increase of salt strength. The results showed that inoculum, various sucrose concentrations and salt strength have significant influences on adventitious roots growth, secondary metabolite and polysaccharide synthesis in P. ginseng.

Dynamic change of metabolites and nutrients in suspension cells of Panax Quinquefolium L. in bioreactor

In order to understand how the nutrient elements were taken up during the cell growth as well as the production of metabolites, it was quite necessary to identify the dynamic change of metabolites and nutrients in suspension cells of Panax quinquefolium in bioreactor. In this study, dynamic accumulation of biomass and ginsenosides Re, Rb1 and polysaccharide as well as major nutrients consumption in cell suspension culture of P. quinquefolium in a 5-L stirred tank bioreactor were investigated. The dry cell weight and the contents of ginsenosides Re, Rb1 and polysaccharide reached the maximum peak simultaneously on about 21 days and the results showed that cell growth and metabolites synthesis related to nutrients consumption. For this reason, we supposed that the contents of metabolites can be increased through added nutrient at the right moment. These results provided theory reference for two-stage or continuous perfusion culture in suspension cells of P. quinquefolium in bioreactor.

Application of gamma irradiation in ginseng for both photodegradation of pesticide pentachloronitrobenzene and microbial decontamination

This study investigates the feasibility of using gamma irradiation for photodegradation of a common residual fungicide, pentachloronitrobenzene (PCNB), in ginseng, and for microbial decontamination. American ginseng, Panax quinquefolius, was subjected to gamma irradiation. PCNB residues were analyzed by gas chromatography with electron capture detection and mass spectrometry. Eighty percent of PCNB (100 ppm) in a methanol aqueous solution was degraded by 5 kGy irradiation, and the primary degradation product was pentachloroaniline. Furthermore, contaminated PCNB (3.7 ppm) in ginseng were reduced to 0.2 ppm after 20 kGy irradiation. The IC 50 for treatment of Sclerotium rolfsii with 20 kGy irradiated PCNB was about 2.7 times higher than that for treatment with unirradiated PCNB. The survival rate of mouse fibroblast L929 cells treated with 20 kGy irradiated PCNB was about 12.9% higher than that of L929 cells treated with unirradiated PCNB. Additionally, after 20 kGy irradiation, less than 5% reduction of contents of ginsenoside Rb1 and Re were observed, and amounts of ginsenosides Rc, Rd, and Rg1 were not reduced significantly. The minimal gamma dose for microbial decontamination was 10 kGy. Therefore, gamma irradiation can be used for both PCNB photodegradation and microbial decontamination of ginseng without obvious loses of ginsenoside contents.

Influence of rare earth element Ce and La addition on corrosion behavior of AZ91 magnesium alloy

AbstractTwo types of AZ91 magnesium alloys containing rare earth element Ce or La were fabricated. Hydrogen evolution and electrochemical tests were carried out to evaluate the corrosion behavior of new AZRE (RE = Ce or La) and AZ91 alloys in 3.5% NaCl solutions (pH 6.50). Various corrosion rate tests indicated that addition of RE obviously enhanced corrosion resistance of AZ91 magnesium alloy. The optimal content of RE was 0.92% for Ce and 0.66% for La. Scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and low‐angle X‐ray diffraction (XRD) were used to characterize the effect of RE addition on microstructure and corrosion product film of AZ91 magnesium alloy. The refined β phase and formation of γ phase in AZRE alloy were observed by SEM, which resulted in the improvement of corrosion resistance due to the depression of microgalvanic couples. Moreover, the enhanced protective effectiveness of corrosion products was another reason for the improved corrosion resistance.

RHENIUM-RICH MOLYBDENITE AND RHENIITE IN THE PAGONI RACHI Mo-Cu-Te-Ag-Au PROSPECT, NORTHERN GREECE: IMPLICATIONS FOR THE Re GEOCHEMISTRY OF PORPHYRY-STYLE Cu-Mo AND Mo MINERALIZATION

The porphyry-type Pagoni Rachi Mo–Cu–Te–Ag–Au prospect, in northern Greece, is a porphyry-epithermal system hosted by an Oligocene dacite porphyry and quartz–feldspar porphyry dikes. The rare mineral rheniite (ReS2) and molybdenite, with very high contents of Re (up to 4.7 wt% Re), occur in quartz veins along with Fe–Cu sulfides, Pb-, Sn-, and Cl-bearing oxides, hematite, ilmenite and tellurides of Bi; these veins are spatially related to sericitic and transitional sericitic–sodic–potassic alteration. Earlier-formed gold-bearing quartz and magnetite veins with sodic–potassic–calcic alteration and late precious-metal telluride-rich carbonate–quartz veins with argillic alteration contain only minor amounts of molybdenite. The composition of rheniite ranges from almost pure, stoichiometric rheniite with low Mo content to rheniite with up to 5.99 wt% Mo. Petrographic, scanning electron microscope, and structural studies suggest that the high Re content of molybdenite from Pagoni Rachi is the result of the isovalent Re-for-Mo substitution in molybdenite. This fact is corroborated by the progressive shortening of the Mo–S mean bond-distance (from 2.414 A in pure molybdenite to 2.355 A), as well as by the isotropic decrease of the unit-cell values with the increase of the Re:Mo ratio. The structural analysis of four molybdenite crystals, with the highest Re content ever reported in nature, demonstrates that they crystallize as the 2 H polytype and not the 3 R polytype, as previously hypothesized, thus suggesting that Re concentration does not correlate with a specific polytype. The fluid inclusions in quartz in the Re-bearing molybdenite–rheniite veins at Pagoni Rachi show that they homogenize to either the liquid or vapor phases (354 to 428°C) or by halite dissolution at 317 to 585°C, which equates to salinities of 40 to 59 wt% NaCl equiv. Rheniite and molybdenite likely precipitated as temperatures fell below 400°C during phase separation under relatively oxidizing conditions, at elevated chlorine activity, and from relatively acid hydrothermal solutions. However, the presence of Pb oxides, Sn-bearing minerals and tellurides is compelling evidence that rheniite and Re-rich molybdenite may have formed directly from the vapor as sublimates, in a manner similar to the way they are deposited at the Kudriavy volcano, Kurile Islands.

The effect of different content of Al, RE and Si element on the microstructure, mechanical and creep properties of Mg–Al alloys

The effect of Al content and Si addition on the microstructural and creep properties of Mg–Al–RE alloys was investigated in this study. The steady state creep rates were specified and it was found that the creep behavior of the alloy, which is dependent on the stability of the near grain boundary microstructure, was improved by the RE and Si addition. For the AZ91 alloy, the results indicate a mixed mode of creep behavior, with some grain boundary effects contributing to the overall behavior. However for the RE and Si added samples, sliding of grain boundaries was greatly suppressed and the dislocation climb controlled creep was the dominant deformation mechanism. Analysis of creep rates also showed that the Si addition resulted in formation of Mg 2Si particles (in Chinese Script form) which have a high thermal stability. After Si addition the steady state creep rates were decreased and the creep resistance was improved. This was due to formation of Mg 2Si particles which change the deformation mechanism at elevated temperatures. Addition of cerium rich misch metal to AZ91 alloy resulted in formation of needle shape particles, which also had a very high thermal stability, providing increased creep resistance and superior mechanical properties compared to AZ91 magnesium alloy. As a result, the grain boundaries were less susceptible for grain boundary sliding at high temperatures. By decreasing the Al content of the alloy having 2 wt.% RE from 9 to 4 wt.%, the steady state creep rate was also decreased compared to AZ91 + 2% RE alloy. The fracture mechanism was also investigated and it was observed that although the Si addition improves the creep resistance, it can make the alloy brittle at ambient temperature.

Effects of steaming the root of Panax notoginseng on chemical composition and anticancer activities

Abstract The root of Panax notoginsen g has been shown to change its saponin composition upon steaming. This study examines the effects of different steaming times and temperature on notoginseng root for saponin composition and anticancer activities. Steaming decreased the content of notoginsenoside R1, ginsenosides Rg1, Re, Rb1, Rc, R2, Rb3 and Rd, but increased the content of Rh1, Rg2, 20 R -Rg2, Rg3 and Rh2. Steaming significantly influenced the transformation of Rg3. The amount of ginsenoside Rg3, an anticancer compound, was 5.23-fold greater in root steamed for 2 h at 120 °C than at 100 °C, and 3.22-fold greater when steamed for 4 h than for 1 h at 120 °C. For anticancer effects, the extract of steamed root significantly inhibited proliferation of SW-480 human colorectal cancer cells. The IC 50 of the steamed extract for 1, 2, 4 and 6 h at 120 °C was 259.2, 131.4, 123.7 and 127.1 μg/mL, respectively; the effect of unsteamed extract was low. Flow cytometric analysis demonstrated that the apoptotic cell induction rates of SW-480 cells were 56.3% and 64.4% with 150.0 and 200.0 μg/mL extract steamed for 6 h. Compared with Rg1 and Rb1, only Rg3 had a significant antiproliferative effect.

Quantitative analysis of ginsenosides Rb1, Rg1, and Re in American ginseng berry and flower samples by ELISA using monoclonal antibodies

Quantitative analysis of ginsenosides Rb1, Rg1, and Re in American ginseng berry and flower samples, which were collected in various months throughout the year, was performed by enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies. The American ginseng flower had the highest content of ginsenosides Rb1, Rg1, and Re (GRb1, GRg1, and GRe). The content of GRb1, GRg1, and GRe decreased in going from young through to ripe berry.