The rolling force model is the core of rolling model, and the prediction accuracy of the Zr-4 alloy cold rolling force model directly affects the control accuracy of the thickness and shape of the ...Zr-4 alloy strip. In this paper, the cold rolling force model of the nuclear power Zr-4 alloy is studied based on the adaptive Particle Swarm Optimization (PSO) algorithm. The cold rolling deformation resistance model of the nuclear power Zr-4 alloy was obtained by field actual sampling and tensile test. The friction coefficient model of the nuclear power Zr-4 alloy was studied based on the Particle Swarm Optimization (PSO) algorithm according to the field measured rolling force value. According to the Hill model, a simplified method of external friction stress state coefficient model based on global variables is proposed by using the Particle Swarm Optimization (PSO) algorithm. Finally, the cold rolling force model of the Zr-4 alloy is established. Industrial test proves that the average cold rolling force prediction accuracy of the nuclear power Zr-4 alloy is 95.36%, which can effectively guide the rolling control of the nuclear power Zr-4 alloy cold rolling production process.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Molecular dynamics simulation method is carried out to study influence of GaAs crystal anisotropy on deformation behavior and residual stress distribution of nanoscratching. The scratching process of ...three crystal orientations of GaAs100, GaAs110 and GaAs111 is investigated, respectively. It is found that there exists significant crystal anisotropy of the deformation behavior and residual stress distribution. Meanwhile, atomic pile-up, destruction depth, scratching force, surface topography, internal structure, residual stress are closely related to the GaAs crystal orientations. A new method to study the residual stress distribution of nanoscratching is proposed. It is observed that the residual stress is focused on the scratching region and its limits, and the two sides of the scratch are distributed symmetrically. The component of residual stress at the GaAs100 scratching bottom is mainly the compressive stress in the y-axis direction. The average scratching force for the GaAs110 scratch is the smallest and the pile-up height on the upper surface of the GaAs110 workpiece is the largest. Eventually, the destruction depth of the crystal structure of the GaAs110 workpiece by the abrasive in the scratching process is the smallest among three crystal orientations, while that of the GaAs100 scratch is the largest among three crystal orientations.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
For actual background, it is important to accurately determine the entire rolling process temperature distribution of the zirconium alloy. To meet the need for multi-pass and small-reduction hot ...rolling of nuclear zirconium alloy plate, temperature field models are established by using the control volume heat balance method. Meanwhile, verifying the employed model, a comparison is made between the predicted and history-recorded temperature of each pass, which is showing a good agreement. Based on the present temperature model, we used for off-line applications about rolling schedule optimized design, and the comparison provides an effective path as a reference of practical control technology. We constitute a step toward the online control of zirconium alloy plates during hot rolling.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Flavonoids are secondary metabolites of plants that often have medical applications. The influences of different sample drying pretreatments on flavonoids and antioxidant activity of ferns have not ...studies. Dryopteris erythrosora leaves used to analyze flavonoid alterations resulting from drying pretreatments. The total flavonoid content of D. erythrosora leaves exposed to different pretreatments was significantly different. The total flavonoid content of samples initially air-dried in shade and then oven-dried at 75°C were the highest (7.6%), while samples initially dried at 75°C had the lowest content (2.17%). Antioxidant activities of D. erythrosora leaves with different pretreatments varied. Group B first air-dried in the shade and then oven-dried at 75°C and group C first air-dried in the sun and then oven-dried at 75°C, both showed relatively stronger antioxidant activity. The best pretreatment for preserving the flavonoids was to first dry the plant material in the shade and then complete the drying process in an oven at 75°C. It was tentatively identified 22 flavonoids among the four different pretreatments by HPLC-ESI-TOF-MS.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
► Flavonoids derivatives of Dryopteris erythrosora were characterized by HPLC-DAD–ESI-MS. ► The anticancer and antioxidant activities of flavonoids from D. erythrosora were evaluated. ► The ...relationship between antioxidant and anticancer activity of fern flavonoids was explored. ► The relationship between flavonoids content and antioxidant potential was investigated.
The profiles and bioactivities of flavonoids extracted from Dryopteris erythrosora were investigated. The total flavonoid content in full plant of D. Erythrosora is about 14.33%. The main flavonoids in D. Erythrosora were identified as gliricidin 7-O-hexoside, apigenin7-O-glucoside, quercetin 7-O-rutinoside, quercetin 7-O-galactoside, keampferol 7-O-gentiobioside, keampferol-3-O-rutinoside, myricetin 3-O-rhamnoside and quercitrin by means of HPLC-DAD–ESI-MS. Flavonoids (0.36mg/ml) extract from D. erythrosora showed similar 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS), superoxide anion scavenging potential and ferric reducing antioxidant potential (FRAP) with that of rutin (0.80mg/ml). However, the antioxidant power by FRAP assay of 0.36mg/ml flavonoids extract from D. erythrosora was much weaker than that of 0.80mg/ml rutin. Moreover, the flavonoids extract from D. erythrosora showed obvious cytotoxic effects on A549 cells. The antioxidant activities of flavonoids extracts from 69 ferns showed a significant reciprocal proportion to the total flavonoids contents. The flavonoids extract from D. erythrosora exhibited a dose-dependent inhibition against acetylcholinesterase. Moreover, the anticancer activity slightly increased with improving antioxidant potential of fern flavonoids. Fern flavonoids are excellent function foods.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Silicon carbide (SiC) ceramics play a key role in various engineering applications due to their desirable properties, however, they are typical hard-brittle materials and famous for their poor ...machinability. Ultrasonic-assisted grinding, a processing method hybridizing the conventional grinding and ultrasonic vibration (UV) machining, is employed as the one applicable machining method for hard-brittle materials. This study focuses on internal grinding of SiC ceramics with the assistance of the UV, and its ductile-brittle transition behavior in the grinding process were investigated experimentally. Following the processing principal of internal grinding and UV machining (i.e., UV-assisted internal grinding, UVAIG), the UVAIG experiment rig were constructed. Conventional internal grinding (CIG) tests, i.e., internal grinding without UV, were also performed on the constructed rig for comparison. In addition, the grinding force and the grinding chips variation behavior with the UV amplitude were also investigated to explore the ductile-brittle transition mechanism in UVAIG. The experiment results evidence that (1) ductile mode grinding is easily achieved in UVAIG, and the critical depth of the cut is deeper in UVAIG than that in CIG, i.e., 0.072 μm in CIG and 0.093 μm in UVAIG; (2) increasing of the critical depth of cut in UVAIG is likely owing to the lower grinding force in UVAIG than that in CIG; and (3) the ultrasonic vibration acted on the axis of the grinding wheel helps in the removal of material on the work-surface, but decreases the grinding energy in the ductile-brittle transition.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Dihydroflavonol 4-reductase (DFR), a key enzyme involved in the biosynthesis of anthocyanins, has been cloned from various species. However, little research has been conducted on this enzyme in ...ferns, which occupy a unique evolutionary position. In this study, we isolated two novel DFR genes from the fern Dryopteris erythrosora. In vitro enzymatic analysis revealed that DeDFR1 and DeDFR2 enzymes can catalyze dihydrokaempferol and dihydroquercetin but cannot catalyze dihydromyricetin. Amino acid sequence analysis showed that DeDFR1 and DeDFR2 have an arginine at the same substrate-specificity-determining site as that in the ferns Salvinia cucullata and Azolla filiculoides. Thus, we speculate that the Arg-type DFR is a new DFR functional type. To further verify the substrate preferences of the Arg-type DFR, an amino acid substitution assay was conducted. When N133 was mutated to R133, Arabidopsis DFR protein completely lost its catalytic activity for dihydromyricetin, as observed for DeDFR1 and DeDFR2. Additionally, heterologous expression of DeDFR2 in the Arabidopsis tt3-1 mutant resulted in increasing anthocyanin accumulation. In summary, DeDFR1 and DeDFR2 are considered to be a new type of DFR with unique structures and functions. The discovery of the Arg-type DFR provides new insights into the anthocyanin biosynthesis pathway in ferns.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The seasonal dynamics of the total flavonoid contents in various parts of Dryopteris erythrosora, a traditional Chinese medicinal fern, and their antioxidant activity were investigated. The total ...flavonoids content in various parts of D. erythrosora showed an obvious seasonal dynamic change. The total flavonoid contents in stems (from 4.3% to 12.5%) were much higher than that in leaves with an average content of 2.01%. In spring, the total flavonoid contents in stems were relatively low, but increased rapidly from summer to winter. However, the seasonal dynamics of total flavonoid contents in leaves showed different model. The total flavonoid contents in the stems showed a negative correlation with that in the leaves from January to July. The correlation coefficient of about -0.7 was obtained. The antioxidant activity of the extracts also altered in proportion to the change of total flavonoid contents. In general, the extracts from stems always showed highest antioxidant potentials and it was suggested that the stems can be used as crude medicine.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Magnetorheological finishing (MRF), considered as a promising polishing technique that can finish a nano-level smooth surface and free of surface or subsurface damage, has been widely utilized in ...ultra-smooth polishing of hard-to-machine materials. MRF process is mainly rely on shear stress to remove material. In this study, α-cellulose used as an additive agent to improve the rheological properties of magnetorheological polishing slurry (MRPS). The rheometer measurement results and polishing results showed that: (1) α-cellulose can enhance the shear stress of MRPS, but increased the apparent viscosity of MRPS. (2) α-cellulose can effectively improve the stability of MRPS, when the weight fraction of α-cellulose was 0.6 wt%, both stability and internal uniform of MRPS can be obtained. (3) If the weight fraction of α-cellulose was bigger than 0.6 wt%, the machining ability of MPRS was stable and the smooth polished surface can be obtained.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Marchantia polymorpha L. is a representative bryophyte used as a traditional Chinese medicinal herb for scald and pneumonia. The phytochemicals in M. polymorpha L. are terpenoids and flavonoids, ...among which especially the flavonoids show significant human health benefits. Many researches on the gametophyte of M. polymorpha L. have been reported. However, as the reproductive organ of M. polymorpha L., the bioactivity and flavonoids profile of the archegoniophore have not been reported, so in this work the flavonoid profiles, antioxidant and acetylcholinesterase inhibition activities of the extracts from the archegoniophore and gametophyte of M. polymorpha L. were compared by radical scavenging assay methods (DPPH, ABTS, O(2-)), reducing power assay, acetylcholinesterase inhibition assay and LC-MS analysis. The results showed that the total flavonoids content in the archegoniophore was about 10-time higher than that of the gametophyte. Differences between the archegoniophore and gametophyte of M. polymorpha L. were observed by LC-MS analysis. The archegoniophore extracts showed stronger bio-activities than those of the gametophyte. The archegoniophore extract showed a significant acetylcholinesterase inhibition, while the gametophyte extract hardly inhibited it.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
PDF
