Fluid mineralization of the Dongtongyu gold deposit in the southern margin of North China craton: Evidence from microthermometry and composition of fluid inclusions

In this study, petrographic, microthermometric, and synchrotron radiation X-ray fluorescence (SRXRF) analyses of fluid inclusions were conducted to shed light on the mineralization mechanism of the Dongtongyu deposit and provide some evidence of the relationship among CO2, Au, and other ore elements (e.g., Cu, Fe, Zn, and Pb) in ore-forming fluids. The ore-forming fluid is characterized as the H2O–CO2–NaCl system with medium–high temperatures and low salinities. Four structural mineralization stages are distinguished: Pyrite-quartz (Stage 1), gold-quartz-pyrite (Stage 2), gold-quartz-polymetallic sulfide (Stage 3), and quartz-calcite (Stage 4). Fluid inclusions in Stages 1–3 are dominated by the H2O–CO2 type, and most of them contain liquid H2O and liquid CO2 at room temperature. The melting temperatures (Tm-CO2 = −82.1°C to −57.5°C) of solid CO2 in Stage 1 are relatively low. The values of Tm-CO2 in Stages 2–3 are quite close, with ranges of −60.5°C to −56.5°C and −59.2°C to −58.6°C, respectively. The melting temperatures of clathrate in Stages 1–3 are −2.7°C to +7.8°C, −5.5°C to +7.8°C, and +3.7°C to +7.2°C. The homogenization temperatures of the CO2 phase in the H2O–CO2 inclusions of the three stages are measured as −7.5°C to +31.7°C, −7.5°C to +29.3°C, and 7.1°C to +24.1°C. The total homogenization temperatures in Stages 1–3 are 180°C–394°C, 202°C–305°C, and 224°C–271°C, with salinities of 4.3 wt.%–18.2 wt% NaCl, 4.3 wt.%–20.0 wt% NaCl, and 5.3 wt.%–11.0 wt% NaCl, respectively. The laser Raman spectroscopy results show that the CO2–H2O inclusions in the quartz veins contain abundant CO2 and CH4. The SRXFR results show that most of the elements, especially As, Te, and Cu, are more enriched in liquid CO2 than in liquid H2O. The elements of Au, Fe, Ni, Cu, and Pb have higher concentrations in H2O–CO2-type fluid inclusions in Stage 2 than other fluid inclusions in Stages 1–2, suggesting that gold mineralization is closely related to CO2-rich fluids. During the fluid evolution process, fluid immiscibility is an important mineralization mechanism of gold. The increase in CO2 and CH4 and the decrease in the fluid temperature might promote fluid immiscibility

Elliptical-arc-fillet flexure hinges: Toward a generalized model for commonly used flexure hinges

Flexure hinges have been used to produce frictionless and backlashless transmissions in a variety of precision mechanisms. Although there are many types of flexure hinges available, designers often chose a single type of flexure hinge (e.g., circular flexure hinges) without considering others in the design of flexure-based mechanisms. This is because the analytical equations are unique to each kind of flexure hinge. This work offers a solution to this problem in the form of a generalized flexure hinge model. We propose a new class of flexure hinges, namely, elliptical-arc-fillet flexure hinges, which brings elliptical arc, circular-arc-fillet, elliptical-fillet, elliptical, circular, circular-fillet, and right-circular flexure hinges together under one set of equations. The closed-form equations for all the elements in the compliance and precision matrices of elliptical-arc-fillet flexure hinges have been derived. The analytical results are within 10 percent error compared to the finite element results and within 8 percent error compared to the experimental results. The equations for evaluating the strain energy and stress level for elliptical-arc-fillet flexure hinges are also provided. This model can be used as a complementary model for the generalized model for conic flexure hinges

A Novel Position Compensation Scheme for Cable-Pulley Mechanisms Used in Laparoscopic Surgical Robots

The tendon driven mechanism using a cable and pulley to transmit power is adopted by many surgical robots. However, backlash hysteresis objectively exists in cable-pulley mechanisms, and this nonlinear problem is a great challenge in precise position control during the surgical procedure. Previous studies mainly focused on the transmission characteristics of the cable-driven system and constructed transmission models under particular assumptions to solve nonlinear problems. However, these approaches are limited because the modeling process is complex and the transmission models lack general applicability. This paper presents a novel position compensation control scheme to reduce the impact of backlash hysteresis on the positioning accuracy of surgical robots’ end-effectors. In this paper, a position compensation scheme using a support vector machine based on feedforward control is presented to reduce the position tracking error. To validate the proposed approach, experimental validations are conducted on our cable-pulley system and comparative experiments are carried out. The results show remarkable improvements in the performance of reducing the positioning error for the use of the proposed scheme

Association of FTO polymorphisms with obesity and metabolic parameters in Han Chinese adolescents.

Previous studies have suggested that fat mass-and obesity-associated (FTO) gene is associated with body mass index (BMI) and the risk of obesity. This study aims to assess the association of five FTO polymorphisms (rs9939609, rs8050136, rs1558902, rs3751812 and rs6499640) with obesity and relative parameters in Han Chinese adolescents.We examined a total of 401 adolescents, 223 normal weights (58.7% boys, 41.3% girls), 178 overweight (60.1% boys, 39.9% girls), aging from 14 to 18-years-old, recruited randomly from public schools in the central region of Wuxi, a southern city of China. DNA samples were genotyped for the five polymorphisms by Sequenom Plex MassARRAY. Association of the FTO polymorphisms with BMI, serum fasting plasm glucose (FPG), fasting insulin (FIns), triglyceride (TG) and cholesterol (TC) were investigated.1) Serum FPG, FIns, TG and TC were statistically significant higher than that in normal control group. 2) We found that BMI was higher in the rs9939609 TA+AA, rs8050136 AC+AA, rs1558902 TA+AA and rs3751812 GT+TT genotypes than in wild TT genotypes (rs9939609: P = 0.038; rs1558902: P = 0.038;), CC genotypes(rs8050136: P = 0.024) and GG genotypes (rs3751812: P = 0.024), which were not significant on adjusting for multiple testing. 3) In case-control studies, five polymorphisms were not significantly associated with overweight (p>0.05), haplotype analyses showed non-haplotype is significantly associated with a higher risk of being overweight (p>0.05). 4) There existed no significant statistical difference about FPG, FIns, TG and TC in genotype model for any SNP.Our study has conducted a genetic association study of the FTO polymorphisms with BMI, serum fasting plasm glucose (FPG), fasting insulin (FIns), triglyceride (TG) and cholesterol (TC). Our study found BMI of subjects with A allele of FTO rs9939609 is higher than that with T allele. Further studies on other polymorphisms from FTO and increasing the sample size are needed

The association of FTO gene SNP with obesity related parameters.

<p>Notes M: male; F: female;</p><p>After adjusting for multiple test, <i>P</i>>0.05.</p

Pairwise linkage disequilibrium.

<p>Pairwise linkage disequilibrium.</p

General characteristic of the sampled adolescents by phenotype distribution.

<p>Notes M: male; F: female; * P<0.05.</p