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Suppressing thermal deformation is an effective measure to reduce the thermal error of CNC (computer numerical control), and the machining accuracy of CNC directly determines the quality and accuracy of parts. A cooling pipe is designed for the non-heat source parts with large swing head deformation to restrain its thermal deformation. At present, there is a lack of research results in this field. Through the finite element simulation analysis of 5AS01 five-axis direct drive swing head, the thermal deformation of swing head and motorized spindle is compared. It has been determined that the thermal deformation of the shell in the Z- and X-axes has a significant impact on the precision of the swing head's machining; thus, steps must be taken to limit its deformation. The cooling position was determined by simulating the normal working condition of the shell and gray correlation analysis. Capillary copper tube was connected with water-cooling system for cooling, and the heat transfer performance between the shell and copper tube was improved by using heat conductive silica gel sheet. Comparing the shell cooling simulation with the shell cooling experiment, it is found that both of them have the same trend in restraining the thermal deformation of the shell, reducing the thermal deformation in X direction by more than 50% and in Z direction by more than 24%. It verifies the accuracy of the cooling simulation model and the effectiveness of this cooling method, which can effectively reduce the thermal deformation of the shell and improve the machining accuracy of the machine tool. [ABSTRACT FROM AUTHOR]

High-speed motorized spindle is an important component of machine tool, and the influence of heat and deformation generated in the working process on the machining accuracy cannot be ignored. In order to reduce the temperature of the motorized spindle in the machining process, this paper first explores the influence of the flow rate of the motorized spindle cooling water on the cooling water jacket and the overall temperature change. The results indicate that when the flow rate exceeds a certain range, the overall temperature no longer drops, so there is an optimal flow rate in the choice of flow rate. Secondly, to solve the problem of uneven axial temperature distribution of the traditional spiral water jacket, four kinds of cooling water jackets with different structures were proposed. The simulation results show that the difference in temperature distribution inside the serpentine water jacket is small, the overall temperature was reduced by 1.8 °C and the pressure drop was reduced by 62.54 kPa. It shows that the serpentine cooling water jacket has better cooling performance and can effectively reduce the thermal deformation of the motorized spindle shafting, so as to achieve the purpose of improving the machining accuracy. [ABSTRACT FROM AUTHOR]

The herbicide atrazine (ATZ) has a detrimental effect on the health of aquatic ecosystems and has become a global concern in recent years. But the understanding of its persistence and potential toxicity under combined pollution, especially in the coexistence of other emerging pollutants, remains limited. In this work, the dissipation and transformation of ATZ in combination with graphene oxide (GO) in water were investigated. Results showed that dissipation rates of ATZ dramatically increased by 15–95% with half-lives shortened by 15–40% depending on initial concentrations of ATZ, and the products were mainly toxic chloro-dealkylated intermediates (deethylatrazine (DEA) and deisopropylatrazine (DIA)), but their contents were significantly lower under the coexistence of GO compared to ATZ alone. In the presence of GO, the nontoxic dechlorinated metabolite hydroxyatrazine (HYA) was detected earlier than 2–9 days, and ATZ transformation into HYA was increased by 6–18% during 21-day incubation periods. This study indicated that the coexistence of GO enhanced the dissipation and detoxification of ATZ. From a remediation standpoint, GO-induced hydrolytic dechlorination of ATZ can reduce its ecological toxicity. But the environmental risks of ATZ for aquatic ecosystem under the coexistence of GO should still be given the necessary prominence due to the potential hazard of ATZ adsorbed on GO and the predominant degradation products (DEA and DIA). [ABSTRACT FROM AUTHOR]

In order to solve the problem that thermal deformation of CNC machine tools affects machining accuracy, a simulated internal cooling structure based on external copper tube is studied. Method of reducing thermal error of machine tool by cooling temperature sensitive position. Taking 5AS01 double swing angle milling head as the research object, the finite element simulation of temperature field and deformation field is carried out through three-dimensional modeling. It is analyzed that the thermal deformation of the swing head shell in X- and Z-directions has great influence on the thermal error of the motorized spindle, so the cooling of its temperature-sensitive position is studied. The thermal distribution of the shell under normal working conditions was simulated statically, and four temperature-sensitive positions were selected from 10 temperature measuring points by grey relational analysis. The straight capillary copper tube combined with thermal conductive silica gel was used for liquid cooling. Experiments show that the thermal deformation of the shell can be effectively reduced by about 50% by cooling the temperature sensitive points, which provides a reference for the optimization of the structure of the pendulum, and indirectly improves the machining accuracy of the motorized spindle, thus improving the machining accuracy of the machine tool. [ABSTRACT FROM AUTHOR]

Two industrial ship plate steels, one having delamination and the other having no delamination during the impact tests at − 60 and − 80 °C, were studied to clarify the effect of delamination on ductile fracture. The instrumented impact tests recorded the load and absorbed energy. The microhardness maps at the selective section of the broken specimen were drawn to display the tendency of strain hardening and the stress state during fracture. The delamination morphology was observed to clarify the reason for the delamination in heavy-gauge steel. The texture transform characteristics were correlated with the initial and deformed microstructures. The results demonstrated that the delamination formed before the main fracture surface and divided the stress concentration into two parts during the impact test. Furthermore, by transmitting much plastic deformation into the specimen far away from the fracture edge and giving full play to the characteristics of crystallographic texture rotation, the severe stress concentration and grain breakage could be avoided. At the same time, the region that should have been formed a radial zone with a plane strain state at the lower part of the fracture could be eliminated and still maintain a ductile fracture contributing to the absorbed energy of 63 J. The segregation of Mn element, different plastic deformation ability between ferrite and bainite, and the crystallographic texture of <001>//ND orientation caused the delamination. [ABSTRACT FROM AUTHOR]

High-speed electric spindle is an important part of computer numerical control (CNC) machining equipment. The thermal displacement generated by the electric spindle during operation is the main reason that affects the machining stability and machining accuracy of the electric spindle. Compensating the thermal error of the high-speed electric spindle can effectively improve the CNC machining. Improve equipment processing performance. Therefore, it is particularly important to establish the accuracy of the thermal error prediction model. Taking the A02 high-speed electric spindle as the research object, ANSYS is used to analyze the thermal characteristics of the electric spindle, and the temperature and thermal displacement monitoring points of the electric spindle are arranged according to the simulation results, and the temperature and thermal displacement data of the monitoring points under different rotational speeds are collected; using K-means to classify temperature measurement points, uses the gray relation analysis degree to determine the correlation between the temperature measurement point and the thermal displacement data, and selects 4 temperature-sensitive points from 10 temperature measurement points. Finally, particle swarm optimization (PSO) is used to optimize the penalty factor and kernel function of support vector machine (SVM), and the PSO-SVM prediction model is established to compare with the neural network prediction model of SVM and genetic algorithm (GA) optimized SVM. The results show that PSO-SVM has better robustness, stability, and generalization ability. [ABSTRACT FROM AUTHOR]

The thermal error of the motorized spindle is an essential factor affecting the machining accuracy of high-speed numerically controlled machines. The establishment of a high-speed motorized spindle thermal error model for thermal error compensation can effectively improve the impact of thermal errors on the machining accuracy of the machine tool. This paper proposes a sparrow search algorithm to optimize the Elman neural network to predict thermal errors in motorized spindles. First is the simulation analysis on thermal characteristics of A02 high-speed motorized spindle. Based on the simulation results, the position of the temperature measuring points is arranged in the temperature and thermal error experiment of the motorized spindle. The temperature and thermal displacement data of high-speed motorized spindle at different rotational speeds were collected; secondly, the method of combining pedigree clustering and k-means clustering is used to perform cluster analysis on each temperature measurement point, and the grey correlation degree is used to determine the correlation between temperature measurement points and thermal error. Three temperature-sensitive points were screened from ten temperature measurement points, which reduced the collinearity between temperature measurement points and the number of independent variables of the model. Finally, the weights and thresholds of the Elman neural network are optimized by the sparrow search algorithm, and the thermal error prediction model of motorized spindle based on SSA-Elman neural network is established and compared with Elman neural network and Particle Swarm Optimized Elman Neural Network prediction model. The results show that the SSA-Elman neural network model has the highest prediction accuracy and exhibits good stability and generalization ability. [ABSTRACT FROM AUTHOR]

To evaluate combined effects of co-existed pesticides and nanomaterials on aquatic plants, the toxicity of herbicide atrazine (ATZ) on Iris pseudacorus in the presence and absence of Graphene oxide (GO) was investigated using chlorophyll a fluorescence transients. Results showed that GO reduced ATZ accumulation in plant. ATZ or ATZ combined with GO mainly blocked electron transport beyond QA at PSII as indicated by the sharp rise of the J-step level of fluorescence rise kinetics. The pronounced increase in Fm and the loss of I-step were observed when ATZ was at 2.0 mg·L− 1 implying the damage on the oxygen evolution complex and PSI. GO at environmentally relevant concentration did not exhibit significant photosynthetic inhibitory effects on I. pseudacorus. GO at 1.0 mg·L− 1 promoted photosynthesis of I. pseudacorus under ATZ stress at 2.0 mg·L− 1. These result indicated that the presence of GO alleviated the photosynthesis inhibition by ATZ at high levels. [ABSTRACT FROM AUTHOR]

The combined pollution, instead of single pollution, has become a widespread contamination phenomenon in aquatic environment. However, little information is now available about the joint effects of the combined pollution, especially co-existed pesticides and heavy metals, on aquatic plants. In the present study, using continuous excitation chlorophyll fluorescence parameters and the OJIP transient, comparisons of herbicide atrazine (ATZ) phytotoxicity on Iris pseudacorus between in the presence and absence of cadmium (Cd) were evaluated over an exposure period of three weeks under laboratory conditions. Results showed that both ATZ and Cd were toxic to I. pseudacorus. The ratio Fv/Fo, specific electron transport energy (ET0/RC), and photochemistry efficiency (PIabs and PItotal) of this emergent plant species at individual ATZ and Cd concentrations were significantly lower than those of the control. ATZ mainly inhibited electron transport beyond QA at PSII acceptor side as indicated by the sharp rise of the J-step level of fluorescence rise kinetics. A pronounced K-step and the loss of I-step due to the damage on the OEC and PSI also occurred when ATZ was at or above 1.0 mg·L−1. In comparison to ATZ alone, ATZ combined with Cd resulted in a lower amplitude rise in J-step with apparent J-I and I-P phases; and significantly lower Fo with higher Fv/Fo, as well as greater ET0/RC with higher values of PIabs and PItotal. However, the adverse influences of ATZ combined with Cd on the above indicators were still significant as compared with the control. Therefore, the coexistence of Cd alleviated the individual phytotoxicities of ATZ, whereas combined pollution of ATZ and Cd still induced the decline in photosynthetic performance of I. pseudacorus, and its potential ecological impacts on the aquatic vegetation cannot be ignored. Our findings offer a better understanding of the joint effects of the pesticide and heavy metal on non-target aquatic plants, and provided valuable insights into the interaction of these pollutants in aquatic environment. [ABSTRACT FROM AUTHOR]

Background: Inflammation is one of major contributors of diabetic osteoporosis. Here, we combined adipose tissues derived mesenchymal stem cells (AD-MSCs)-derived exosomes and microRNA-146a (miR-146a) to develop more effective anti-inflammation strategy in osteoclasts. Methods: miR-146a was overexpressed in AD-MSCs and miR-146a exosomes (miR-146a-Exo) were isolated and characterized. Cellular and animal diabetic osteoporosis models were created to evaluate the anti-inflammation effect of miR-146a-Exo by using ELISA, qRT-PCR, MTT, bone resorption assay, Western blot, and bone mineral content and density analysis in vitro and in vivo. Results: miR-146a-Exo administration presented the most potent effect on inhibition of pro-inflammatory cytokines production in high glucose-treated osteoclasts, restraint bone resorption, and restoration of the bone loss in streptozotocin-induced diabetic osteoporosis rats. Mechanistically, miR-146a-Exo suppressed the expression of TNF-α, IL-18, and IL-1β, induced the inactivation of inflammasome, and finally reduced bone resorption and recovered bone loss. Conclusion: Combination of AD-MSCs-Exo and miR-146a more effectively exert the anti-inflammation effect in osteoclasts, providing a potential drug for the treatment of diabetic osteoporosis. [ABSTRACT FROM AUTHOR]

To understand the influence of Cd on atrazine (ATZ) degradation in aqueous solution, the degradation of different initial levels of ATZ (0.1, 0.5, 1.0, and 2.0 mg·L−1) was investigated in the presence and absence of Cd2+ in a 20-day laboratory experiment. It was found that Cd2+ caused a significant decrease in ATZ degradation and increased its half-life from 17–34 days to 30–57 days (p < 0.0001). Regarding the three most common metabolites of ATZ, deethylatrazine (DEA) and deisopropylatrazine (DIA) were detected in water earlier than hydroxyatrazine (HYA). The DEA content was several times higher than the DIA and HYA contents, regardless of the presence or absence of Cd2+. In the presence of Cd2+, the DIA content was significantly lower and the HYA content was significantly higher. Furthermore, Cd2+ had a dose-dependent effect on HYA formation. Our results indicated that the coexistence of Cd2+ and ATZ resulted in greater herbicide persistence, thereby possibly increasing the risk of environmental contamination. DEA was still the predominant ATZ degradation product detected in water under the combined pollution, which was similar to the ATZ tendency. [ABSTRACT FROM AUTHOR]

Atrazine is frequently detected in surface runoff and poses a potential threat to the environment. Grass hedges may minimize runoff loss of atrazine from crop fields. Therefore, the effectiveness of two grass hedges (Melilotus albus and Pennisetum alopecuroides) in controlling atrazine runoff was investigated using simulated rainfall on lands at different slope gradients (15 and 20%) in northern China. Results showed that a storm (40 mm in 1 h), occurring 4 h after atrazine application, caused a loss of 3% of the applied amount. Atrazine loss under 20% slope was significantly greater than that under 15% slope in control plots. Atrazine exports associated with the water fraction accounted for the majority of total loss. Pennisetum hedges were more efficient in controlling atrazine loss with runoff compared to Melilotus hedges. No significant difference in the capacity of grass hedges to reduce atrazine exports was observed between 15 and 20% slopes. These findings suggest grass hedges are effective in minimizing atrazine runoff in northern China, and Pennisetum hedges should be preferentially used on sloping croplands in similar climatic regions. [ABSTRACT FROM AUTHOR]

Biochar produced from rice straw (RC) and maize stalk (MC) was amended to the heavy metal-contaminated soil to investigate the effects of different biochar feedstock and particle size (fine, moderate, coarse) on the accumulation of Cd, Zn, Pb, and As in Brassica chinensis L. (Chinese cabbage). The concentrations of Cd, Zn, and Pb in shoot were decreased by up to 57, 75, and 63%, respectively, after biochar addition (4%). Only MC decreased As concentration in B. chinensis L. shoots by up to 61%. Biochar treatments significantly decreased NHNO-extractable concentrations of Cd, Zn, and Pb in soil by 47-62, 33-66, and 38-71%, respectively, yet increased that of As by up to 147%. Amendment of RC was more effective on immobilizing Cd, Zn, and Pb, but mobilizing soil As, than MC. A decrease in biochar particle size greatly contributed to the immobilization of Cd, Zn, and Pb in soil and thereby the reduction of their accumulations in B. chinensis L. shoots, especially RC. Increases in soil pH and extractable P induced by biochar addition contributed to the sequestration of Cd, Zn, and Pb and the mobilization of As. Shoot biomass, root biomass, and root system of B. chinensis L. were enhanced with biochar amendments, especially RC. This study indicates that biochar addition could potentially decrease Cd, Zn, Pb, and As accumulations in B. chinensis L., and simultaneously increase its yield. A decrease in biochar particle size is favorable to improve the immobilization of heavy metals (except As). The reduction in Cd, Zn, Pb, and As levels in B. chinensis L. shoots by biochar amendment could be mainly attributed to a function of heavy metal mobility in soil, plant translocation factor, and root uptake. [ABSTRACT FROM AUTHOR]

3D carbon linked by uniform sized nanospheres was successfully prepared by hydrothermal carbonization method. It is found that the increasing reaction temperature and extending reaction times have a similar effect on the morphology of the products, which could evolve from nanospheres to 3D carbon linked by nanospheres or layered structure. The final chemical structure of the products can be switched from a carbon rich in oxygen containing functional groups type to a carbon network of extensive aromatic domain. [ABSTRACT FROM AUTHOR]

Greenhouse experiments were conducted to investigate the influence of rice straw biochar (RSB) on soil cadmium (Cd) availability and accumulation in lettuce. The RSB was applied either in bands or broadcast in the test site of four greenhouses with soil Cd concentrations ranging from 1.70-3.14 μg g. Biochar doses applied in bands were half of those broadcast. The Cd levels in the shoots of lettuce were observed to be reduced by up to 57% with increasing RSB application rate (0, 6, 12, 18 t ha). Following RSB application, shoot Cd concentrations of lettuce were reduced to below the Chinese threshold value set for food, and hazard quotients for Cd associated with vegetable consumption were reduced from 0.70-1.11 to 0.42-0.65. A decrease in soil bulk density (11%) and increases in water holding capacity (16%), available phosphorus (30%), available potassium (197%), and lettuce yield (15%) were observed after RSB application. Multiple linear regression analysis suggested that the soil extractable Cd level (but not biomass dilution) and soil bulk density, as influenced by RSB addition, were the dominant contributors to the shoot Cd levels in lettuce and lettuce yield, respectively. These results highlight the potential for RSB to mitigate the phytoaccumulation of Cd and thereby to reduce human exposure from vegetable consumption. Application of biochar in band, rather than broadcasting over the entire area, represents an opportunity to halve the biochar cost while retaining a good remediation effect. [ABSTRACT FROM AUTHOR]

The potential of Acorus calamus to remove chlorpyrifos from water was assessed under laboratory conditions. Toxic effects of the insecticide in A. calamus were evaluated using pulse-amplitude modulated chlorophyll fluorescence techniques as well. At exposure concentrations above 8 mg L, A. calamus showed obvious phytotoxic symptom with significant reduction in quantum efficiency of PSII (ΦPSII) and photochemical quenching coefficient (qP) in 20-day test; the inhibition of maximal quantum efficiency of PSII (Fv/Fm) was accompanied by a significant rise in initial chlorophyll fluorescence (Fo) within 15-day exposures. Fv/Fm and Fo recover to the normal level after 20-day exposure. The reduced removal rate to chlorpyrifos was observed with increase of initial chlorpyrifos concentrations. At application levels of 1, 2, and 4 mg L, the disappearance rate of chlorpyrifos in the hydroponic system with plants was significantly greater than that without plants during the 20-day test periods. Chlorpyrifos was taken up from medium and transferred to above ground tissues by the plant and significant amounts of chlorpyrifos accumulated in plant tissues. The result indicated that A. calamus can promote the disappearance of chlorpyrifos from water and may be used for phytoremediation of water contaminated with a relatively low concentration of chlorpyrifos insecticide (<4 mg L). [ABSTRACT FROM AUTHOR]

The emergent plants Acorus calamus, Lythrum salicaria, and Scirpus tabernaemontani were exposed to atrazine for 15, 30, 45, and 60 days in a hydroponic system. Effects were evaluated investigating plant growth, chlorophyll (Chl) content, peroxidase (POD) activity, and malondialdehyde (MDA) content. Results showed that selected plants survived in culture solution with atrazine ≤8 mg L, but relative growth rates decreased significantly in the first 15-day exposure. Chl a content decreased, but MDA increased with increasing atrazine concentration. S. tabernaemontani was the most insensitive species, followed by A. calamus and L.salicaria. The growth indicators exhibited significant changes in the early stage of atrazine exposure; subsequently, the negative impacts weakened and disappeared. Plant growth may be more representative of emergent plant fitness than physiological endpoints in toxicity assessment of herbicides to emergent plants. [ABSTRACT FROM AUTHOR]

The emergent hydrophyte Iris pseudacorus was constantly exposed over a 35-day period to atrazine in the laboratory. It could survive at an atrazine level up to 32 mg/L. Its relative growth rates were inhibited significantly when exposure dosage reached at or exceeded 2 mg/L ( p < 0.05). No observed effect concentration and lowest observed effect concentration for growth were 1 and 2 mg/L, respectively. Chlorophyll a and b contents of the plant in all treatment groups were affected significantly, and chlorophyll a/ b ratios of all atrazine treatment levels were pronouncedly higher than those of the control within 5 days of exposure ( p < 0.05), but thereafter recovered to the level of the control. Differences of photosynthetic efficiency were significant between all atrazine treatments and the control; except for 1 mg/L on day 1 and 5, and 2 mg/L on day 1. I. pseudacorus did not show phytotoxicity symptoms after 35 days exposure to atrazine below 2 mg/L level, but photosynthetic efficiency had begun to decline. [ABSTRACT FROM AUTHOR]

This study aims to investigate the correlation between the different characteristics of plaques, plasma level of homocysteine (Hcy), and gene polymorphism of Hcy metabolism-related enzyme. In this consecutive case-control study, we measured the plasma Hcy level using fluorescence biochemistry method and examined the gene polymorphism of Hcy metabolism-related enzyme methylenetetrahydrofolate reductase (MTHFR) C677T using TaqMan probe technology. We also examined these using intravascular ultrasound. We studied the characteristics of the plaque, measured the cross-sectional areas of the external elastic membrane and the lumen, calculated the plaque area, plaque burden, and eccentricity index, and examined the remodeling index. Hard plaques were more dominant in the (SPA) group, whereas soft plaques were more dominant in the acute coronary syndrome (ACS) group ( P < 0.001). The risk of plaque rupture and thrombus is higher in the ACS group ( P < 0.05). Compared with SPA group, plaque burden was heavier in the ACS group ( P < 0.05), but the eccentricity index is significantly higher in SPA group than in the ACS group ( P < 0.001). Positive remodeling was more frequent in ACS group, whereas negative remodeling was more frequent in the SPA group ( P < 0.001). Plasma Hcy levels were higher in the unstable than in the stable plaque group ( P < 0.001). The constituent ratio of MTHFR C677T genotype were different in stable plaque group and vulnerable plaque group ( P < 0.05). The T genotype can increase the incidence rate of vulnerable plaque. Hcy and MTHFR C677T gene polymorphism were found to be risk factors for vulnerable plaque. Therefore, these can be used as indices to predict the instability of atherosclerotic plaque. [ABSTRACT FROM AUTHOR]

To summarize the clinicopathological features, therapeutic regimens, and outcomes for patients with primary testicular lymphoma (PTL), we retrospectively reviewed the medical records of 13 patients diagnosed with PTL between 2001 and 2012 at our hospital. Average age at diagnosis was 62.2 ± 13.9 years, and all patients presented with painless testicular swelling. Diffuse large B-cell lymphoma was the dominant histotype (69.2 %). All 13 patients were treated with inguinal orchiectomy and received chemotherapy and/or radiotherapy. Complete follow-up data were available for 10 patients with an average follow-up duration of 28.4 ± 30.9 months. Seven patients were evaluated as Ann Arbor stage I or II, and three as stage III or IV. Eight patients were found to have hypoechogenic and hypervascular signals in the testis on ultrasound examination. Complete remission was achieved in six patients, and four patients who were still undergoing chemotherapy during the last follow-up showed no signs of relapse. Of the 10 patients with complete follow-up records, three had relapses, which occurred in the CNS, epiglottis, and the nasal cavity. Time to relapse in these cases was 2, 7, and 11 months, respectively (3/10). The mean progression-free survival was 22.57 months (range 1.1-101.9 months). [ABSTRACT FROM AUTHOR]

This paper presents a synthetic U-Pb and Hf isotopic study of zircons and a whole-rock geochemical study on diabase swarms that were emplaced into the Proterozoic formations in the Xuzhou-Huaibei area, the southeast margin of North China Craton. Zircons from the diabase dykes display weak oscillatory zoning in the cathodoluminescence (CL) images and show high Th/U ratios (0.91-6.90), both of which are typical of a magmatic origin. The SHRIMP and Q-ICP-MS U-Pb zircon dating results indicate that the diabase swarms were emplaced at ca. 890 Ma. Hf isotopic analysis on these zircons gives ɛ( t) values ranging from 2.26 to 14.74 and Hf model age t and t ranging from 843 to 1321 Ma and from 808 to 1779 Ma, respectively. Geochemically, the diabase swarms are characterized by a relative enrichment in LREE and LILE (Rb, Ba and La), a comparative enrichment in Cr and Ni, but a slight depletement in HFSE (Th, Nb, Ta, Zr and Hf). They are plotted in the within-plate tholeiite series on the tectonic discrimination diagrams. Taken together, these geochemical and isotopic data suggest that the primary magmas to form the diabase dykes in the Xuzhou-Huaibei area could have been derived from a transitional mantle in the Mesoproterozoic, and were most probably emplaced under a continental margin extensional setting at ca. 890 Ma. The results of this study demonstrate that the Neoproterozoic (800-900 Ma)magmatism was not restricted to the Yangtze Block, but also occurred at the southeast margin of the North China Craton. [ABSTRACT FROM AUTHOR]

The petrographic characteristics of Jingshan “migmatitic granite” and the occurrence of the magmatic zircons indicate that the granite was formed by normal crystallization of felsic melts. All zircons in the granite have inherited cores and fine-scale oscillatory zoning rims of magmatic origin. It is realized that the granite was formed at 160.2±1.3 Ma through dating magmatic zircons. The generation of the granitic magma could be related to the lithospheric mantle and/or lower crust delamination after the ultrahigh pressure metamorphism (UHPM) in Triassic. Most inherited zircons yield the ages of 217.1±6.6 Ma, which is consistent with the peak UHPM in the Dabie-Sulu orogenic belt. Some of the inherited zircons (433–722 Ma) constitute a discordia line with the upper intercept age of 850+85/−68 Ma and a lower intercept age of 261+100/−140 Ma. These ages imply that the granite could be derived from the partial melting of the crustal materials of the South China Block that was intensively superimposed by the UHPM. The UHPM could be the reason for the major Pb loss at −220 Ma. [ABSTRACT FROM AUTHOR]

The early Jurassic intrusive complex is chiefly made of monzodioritic porphyry in northern Anhui and northern Jiangsu, which emplaced in 191 Ma. The intrusive complexes contain a lot of eclogite inclusions which belong to eclogite and garnet-pyroxenite. The inclusions had undergone eclogite facies high-pressure metamorphism and amphibolite facies retrogressive metamorphism. The garnets in eclogite inclusions are mainly almandine varieties and clinopyroxenes are omphacite and augite. The mineral assemblage andP-T estimation results show thatP-T conditions of eclogite facies metamorphism and amphibolite facies retrogressive metamorphism are over 1.2–1.5 GPa, 709–861°C and 0.7–1.03 GPa, 666–738°C, respectively. The discovery of the high-pressure xenoliths not only is of important significance to understand the composition and structure of deep crust in southern edge of North China Platform, but also can be of important influence on realizing the subduction-collision-exhumation evolutional process of the Dabie-Sulu ultrahigh-pressure (UHP) metamorphic belt. [ABSTRACT FROM AUTHOR]

Reports on the discovery of eclogite inclusions in eastern China. Presence of monzodioritic porphyry in the early Jurassic intrusive complex in northern Anhui and northern Jiangsu, which emplaced in 191 Ma; Indication the intrusive complexes contain eclogite inclusions that belong to eclogite and garnet-pyroxenite; Evidence the inclusions underwent eclogite facies high-pressure metamorphism and amphibolite facies retrogressive metamorphism; Mention of almandine, as well as, omphacite and augite clinopyroxenes in garnets found in the eclogite inclusions; The mineral assemblage and P-T estimation results showing metamorphism conditions; Significance of the high-pressure xenoliths in understanding the composition and structure of deep crust in the North China Platform; Implication for understanding the subduction-collision-exhumation evolutional process of the Dabie-Sulu ultrahigh-pressure (UHP) metamorphic belt.

The timings of subduction of the Palaeo-Pacific Plate beneath the North China Craton and of associated mineralisation remain unresolved. We studied a granodiorite porphyry in the Banmiaozi gold mining area, located along the northeastern margin of North China Craton, to shed light on these timings. Using zircon U–Pb geochronology, major- and trace-element geochemistry, Sr–Nd isotopes, and biotite compositions, we show that the granodiorite porphyry formed during the early Middle Jurassic and has a composition similar to those of 'C-type adakites' from eastern China. The granodiorite rocks have initial Sr isotopic compositions of 0.713418–0.713694, εNd(t) values of −15.9 to −16.69, and depleted-mantle single-stage model ages of 2.70–2.49 Ga, implying that the parental magma originated via subduction of the Palaeo-Pacific Plate beneath the North China Craton and resulted also in the generation of basaltic magmas and partial melting of thickened lower crust. As the Archaean basement rocks were rich in Au and magnetite, the magma was characterized by high Au contents and oxygen fugacity (fO2 = 10−13 bar). Subsequent mixing with, or contamination by, partially melted Proterozoic marine strata, such as the marble-bearing Laoling Group, played an important role in mineralisation. These country rocks provided large quantities of Cl−, CO32−, and SO42− to the magma, which formed soluble complexes with ore-forming elements such as Au, allowing enrichment and migration of the metals. Our data show that the Banmiaozi gold deposit is an orogenic gold deposit associated with subduction-related adakitic magmatism. [ABSTRACT FROM AUTHOR]