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Environmental pollution has become a pressing global issue, severely threatening human health and ecosystems. As an emerging driver of economic development in countries worldwide, the digital economy (DE) has the potential to enhance resource utilization efficiency and promote the development of clean technologies, thereby reducing environmental pollution. Based on the panel data of 267 cities in China from 2012 to 2021, the spatial econometric model is used to test the impact of DE on environmental pollution. The mediating effect model is used to explore the transmission mechanism of DE affecting environmental pollution. The panel threshold model is used to examine the threshold effect of marketization. The results are as follows: (1) DE can significantly reduce environmental pollution. The conclusion is still valid after conducting robustness tests such as selecting historical data as instrumental variables and the "Broadband China" pilot as a quasi-natural experiment. (2) From the perspective of transmission mechanism, DE can reduce environmental pollution through green technology innovation and industrial structure upgrading. (3) From the perspective of spatial spillover effect, DE can reduce the environmental pollution level of surrounding cities. (4) From the perspective of threshold effect, DE has obvious market-oriented single threshold effect on environmental pollution. When the marketization level crosses the threshold of 11.6611, the emission reduction effect of DE is significant. (5) From the perspective of heterogeneity, DE has a heterogeneous impact on environmental pollution in cities with different geographic locations, resource endowments and administrative level. Regarding geographical heterogeneity, DE can effectively reduce environmental pollution in eastern and central regions, but has no significant impact on environmental pollution in western regions. Regarding the heterogeneity of resource endowment, compared to non-resource-based cities, resource-based cities suffer more from the negative effects of DE on their environment. Regarding the heterogeneity of administrative levels, compared with non-central cities, the DE of central cities has a greater emission reduction effect. Based on empirical results, this paper proposes strategic recommendations in areas such as enhancing the application of DE in emission reduction, upgrading industrial structures, promoting green technology innovation, and improving the level of marketization. This study not only enriches the research of DE and environmental pollution, but also provides a reference for the formulation of environmental pollution control policies. [ABSTRACT FROM AUTHOR]

Improving total factor carbon emission efficiency (TCE) is the key to achieving carbon emission reduction targets while ensuring economic growth. In this paper, the global Malmquist index based on the SBM model is used to measure TCE of 283 cities in China from 2011 to 2019. On this basis, this paper uses the spatial econometric model and intermediary effect model to empirically analyze the impact of industrial co-agglomeration on TCE and its transmission mechanism. Furthermore, considering the differences in geographical location and resource endowment among regions, this paper analyzes the heterogeneous effect of industrial collaboration agglomeration on TCE in different regions and cities. The results show that: (1) Industrial co-agglomeration can improve TCE, and its main transmission channel is technological innovation. (2) Industrial co-agglomeration has a positive spatial spillover effect. Industrial co-agglomeration in one region can improve the TCE in the surrounding regions. (3) Industrial co-agglomeration of cities with different geographic locations and resource endowments has a heterogeneous effect on TCE. Regarding geographical heterogeneity, the industrial co-agglomeration in the eastern region has the greatest promoting effect on TCE, followed by the central region. However, the impact of industrial co-agglomeration in the western region on TCE is not significant. Regarding resource endowment heterogeneity, the industrial co-agglomeration in non-resource-based cities has a greater promoting effect on TCE than that in resource-based cities. [ABSTRACT FROM AUTHOR]

Learning about the regional business model is essential for the sustainable development of the regional economy. From the perspective of urban renewable energy, city A is the product of energy development. This paper analyzes the current situation and existing problems of the industrial model of city A through fuzzy k-means clustering algorithm. The results show that although the optimization of industrial structure in city A has achieved some results, the more intuitive problems mainly include low labor productivity of the primary industry, strong resource dependence, insufficient extension of industrial chain, and slow development of technology intensive industries. This paper uses fuzzy k-means clustering algorithm to select the leading industries from the perspective of the current situation of leading industries, urban development pattern, and regional policies in city A. The results show that, as a renewable resource-based city, the leading industries suitable for the current development of city A include manufacturing, power, alkali gas and water production and supply, transportation, warehousing and postal industry, leasing, and business services. The results of fuzzy k-means clustering algorithm are quite excellent, and the accuracy rate is 93.3%. This paper uses the grey dynamic linear programming model to predict the future development of the Urban A business model and combines the selection of key functions to obtain the best business model: deep and efficient technical equipment as a good goal, achieved through regional logistics, transportation, new services, etc., to enhance the output value of the tertiary industry in city A and optimize the internal structure of the secondary industry in city A. [ABSTRACT FROM AUTHOR]

Lead isotopic compositions of international silicate glasses, feldspar and copper-based samples are obtained using femtosecond laser ablation multiple collector inductively coupled plasma mass spectrometry (fLA-MC-ICPMS). Some international glass standards for the microanalysis are applied to evaluate the method reported here. The Pb isotopic composition of these NIST glasses (SRM 610, 612, 614), USGS (BHVO-2G, BCR-2G, BIR-1G and GSD-1G) and MPI-DING glasses (GOR132-G, KL2-G, T1-G, StHs60/80-G) agree well with recommended values in 2 s error. One of 15 copper-based metals is found to have homogenized Pb isotope data and can be used as an external calibration standard and quality control sample for chalcopyrite, ancient coins, etc., to trace the genesis of metal deposit and culture exchange among different dynasties (GBW02137, 208Pb/ 204Pb = 37.9661 ± 0.0005 (2 s), 207Pb/ 204Pb = 15.5770 ± 0.0002 (2 s), 206Pb/ 204Pb = 17.7462 ± 0.0002 (2 s)). We also prepared a feldspar glass to serve as the external calibration standard/QC for Pb isotope analysis using fLA-MC-ICPMS. [ABSTRACT FROM AUTHOR]

Deep learning has achieved great success on robotic vision tasks. However, when compared with other vision-based tasks, it is difficult to collect a representative and sufficiently large training set for six-dimensional (6D) object pose estimation, due to the inherent difficulty of data collection. In this paper, we propose the RobotP dataset consisting of commonly used objects for benchmarking in 6D object pose estimation. To create the dataset, we apply a 3D reconstruction pipeline to produce high-quality depth images, ground truth poses, and 3D models for well-selected objects. Subsequently, based on the generated data, we produce object segmentation masks and two-dimensional (2D) bounding boxes automatically. To further enrich the data, we synthesize a large number of photo-realistic color-and-depth image pairs with ground truth 6D poses. Our dataset is freely distributed to research groups by the Shape Retrieval Challenge benchmark on 6D pose estimation. Based on our benchmark, different learning-based approaches are trained and tested by the unified dataset. The evaluation results indicate that there is considerable room for improvement in 6D object pose estimation, particularly for objects with dark colors, and photo-realistic images are helpful in increasing the performance of pose estimation algorithms. [ABSTRACT FROM AUTHOR]

The petrogenesis of aluminous A-type granites is a contentious subject. Here, we focused on the North Kudi pluton in the Western Kunlun orogen to investigate the origin and magmatic processes responsible for generating A-type granites. Samples from the North Kudi pluton are metaluminous to weakly peraluminous. K-feldspar granite samples are characterized by high alkali and Cl contents, high HFSE concentrations and FeO/MgO, low F content, negative Ba, Sr, P, Eu, and Ti anomalies, and high magma temperature (>903 °C), showing affinity to aluminous A-type granites. However, their 10,000 × Ga/Al ratios (1.86–3.18) are relatively lower than typical A-type granites. Quartz-monzonite displays similar Sr–Nd isotopic compositions and Ga/Al ratios with the K-feldspar granite but less pronounced negative Sr, P, and Ti anomalies and no discernable negative Ba and Eu anomalies. Fractional crystallization of alkali-rich, Cl-rich, and F-poor magmas can generate some typical geochemical characteristics of A-type granites (e.g., negative Ba, Sr, P, and Eu anomalies) but has little influence on Ga/Al ratios. The enriched Sr–Nd isotopic compositions, high Cl and alkali contents, arc-like geochemical features, and the involvement of slab-derived components, as indicated by high zircon Ce4+/Ce3+ (up to 503), suggest that the North Kudi pluton was possibly derived from partial melting of the metasomatized lithospheric mantle in the time of asthenosphere upwelling during the post-collisional stage. The emplacement of the North Kudi pluton thus indicates the onset of the post-orogenic stage in the Western Kunlun orogen. [ABSTRACT FROM AUTHOR]

In this study, lead isotopic ratios in bronze artifacts were non-matrix-matched determined directly by femtosecond laser ablation multi-collector inductively coupled plasma mass spectrometry (fsLA-MC-ICP-MS). We evaluated the necessity of matrix matching for lead isotope ratio analyses of bronzes by adopting thallium solution to correct mass discrimination during mass spectrometer measurements. Lead isotope ratios of four bronze reference materials were measured by fsLA-MC-ICP-MS to determine the quality of data when calibrating samples with standards having different physical characteristics and chemical compositions. The average 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, 208 Pb/ 204 Pb, 207 Pb/ 206 Pb and 208 Pb/ 206 Pb ratios determined by fsLA-MC-ICP-MS were within 0.06% of that by solution nebulizer MC-ICP-MS (SN-MC-ICP-MS). The results indicate that accurate lead isotopic compositions could be obtained by fsLA-MC-ICP-MS technique after non-matrix-matched standards calibration. Additionally, the lead isotopic compositions are presented for five Chinese bronze reference materials using fsLA-MC-ICP-MS. Homogeneity of lead isotope distribution was expressed as the RSD range from 0.010% to 0.017% for 208 Pb/ 204 Pb, 207 Pb/ 204 Pb, 206 Pb/ 204 Pb ratios. Therefore, the five bronze materials could potentially serve as external calibration standards and quality control samples for in situ lead isotope measurements of ancient bronze artifacts. The fsLA-MC-ICP-MS technique could be applied to differentiate the high radiogenic lead in bronze artifacts from common lead. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrothermal titanite yields a weighted mean 206Pb/238U age of 160.1 ± 4.4 Ma. • Sulfur isotope compositions of ore sulfides indicate minor contributions from the host rocks via fluid-rock interaction. • The variations of in-situ Cu isotope compositions (δ65Cu: −1.13 to +0.12 ‰) are inconsistent with the ancient VMS deposits. • Our results suggest that the Tieshajie deposit has a Late Jurassic magmatic-hydrothermal origin instead of a Meso-Neoproterozoic VMS origin. The Tieshajie Cu deposit, located in the northeastern part of the Qin-Hang Metallogenic Belt (QHMB), South China, has long been regarded as a representative Meso-Neoproterozoic volcanogenic massive sulfide (VMS) deposit. Here we present a hydrothermal titanite U-Pb age, Re-Os and in-situ S-Cu isotope data for chalcopyrite to constrain the timing and ore genesis of the Tieshajie deposit. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb dating of titanite from the disseminated Cu ore yielded a weighted mean 206Pb/238U age of 160.1 ± 4.4 Ma. Chalcopyrite from different ore types has low 187Os/188Os (0.85–3.60) and 187Re/188Os (46.1–614.0) ratios, combined with initial 187Os/188Os (0.74–2.00), excluding a mantle source. A Re-Os isochron age (188 ± 30 Ma) for five chalcopyrite samples is consistent with the titanite U-Pb age within errors. Moreover, the variations in Cu isotope compositions (δ65Cu: −1.13 to +0.12 ‰) and δ34S values (+3.8 to +7.7 ‰) of chalcopyrite are inconsistent with those reported from the ancient VMS deposits in previous studies. Therefore, our results are indicative of a Late Jurassic magmatic-hydrothermal origin instead of a VMS origin for the Tieshajie deposit. In combination with previous studies, we propose that the Tieshajie Cu deposit belongs to the distal part of the Mid-Late Jurassic (170–150 Ma) porphyry-skarn Cu mineralization event in the QHMB, likely triggered by the subduction of the Paleo-Pacific plate during the Late Mesozoic. This study also has new insights into the genesis of Cu mineralization in the QHMB and further provides implications for future exploration. [ABSTRACT FROM AUTHOR]

In this paper, A new plate heat exchanger is proposed based on topology optimization applying the moving asymptote method (MMA), in which, an alternative projection function is applied, and the parameter ranges affecting the topology structure are present. The channel composition, thermal performance, and hydraulic performance of the optimized structure are analyzed. Numerical simulation and experimental analysis are conducted between the topology and the chevron plate heat exchanger for performance comparison. The results present that the parameter ranges affecting the key issues of the topology are provided, which provides reference for parameter selection. The alternative projection function can effectively eliminate grey scale and checkerboard phenomenon. The comparison shows that the comprehensive performance of the topology structure is enhanced, with a maximum increase of 19.85%. • The optimal structure of the plate heat exchanger is obtained with MMA based on topology. • Experimental and numerical studies are carried out to investigate thermal and hydraulic performance. • The alternative projection function is proposed to eliminate grey scale and checkerboard phenomenon. [ABSTRACT FROM AUTHOR]

This study investigates the degradation process of mountain wetlands in the upper Hanjiang River Basin (HRB) over a 30-year span from 1990 to 2020. In particular, the landscape development intensity (LDI) index was employed to conduct a comprehensive assessment of the wetland health. This was subsequently combined with the spatio-temporal changes of water quality in the basin to explore the potential correlations between the health status of mountain wetlands and the associated watershed water quality. The results show that over the past three decades, wetland ecosystems have shrunk by 18% due to conversion into farmland, grass, construction land and forest land. This was significant between 2010 and 2020, as shown by a land use dynamic index of −1.121% during 2010–2020, which was significantly higher than that in the preceding two decades (0.003%, 0.367%) (p < 0.05). LDI values for individual sub-watersheds across different years ranged from 2.39 to 4.93, demonstrating an increasing trend since 2010. This indicates a heightened level of human interference in mountain wetlands. Although the water quality within the basin generally adhered to the Class II surface water quality standard, total nitrogen (TN) (primarily from farming) was a concern. Areas with relatively more human activity were observed to exhibit increased pollution levels, as demonstrated by a positive correlation between LDI and the concentrations of total phosphorus (TP), ammonium nitrogen (NH 4 +-N), and chemical oxygen demand (COD) in the basin. The LDI of the mountain wetland exhibited a consistent positive correlation with the water quality comprehensive function, both during the flood (r = 0.77–0.81) and non-flood (r = 0.61–0.70) seasons (p < 0.05). This indicates the significant impact of the wetland landscape structure on the water quality within a 1000 m radius on either side of the river. Special attention should be paid to the management and allocation of wetland landscapes within this 1000 m buffer zone. Furthermore, efforts to control upstream pollutant emission should be strengthened. [Display omitted] • The total wetland area in the upper HRB decreased by 18% from 1990 to 2020. • LDI index in different years from 1990 to 2020 was between 2.39 and 4.93. • Wetland loss increased significantly from 2010 to 2020. • Mountain riverside wetlands degradation seriously affected by human activities. • Mountain wetland health was related to water quality within 1000 m buffer zone. [ABSTRACT FROM AUTHOR]

Controlling the accuracy and precision of sulfur and lead isotopic compositions in natural sulfide minerals requires the use of well-characterized reference materials with matrices similar to those of the unknown samples being analyzed. However, it is often a challenge to prepare natural or synthetic reference materials with homogeneous isotope compositions on a micro-scale. Herein, we report a novel method to synthesize homogeneous sulfide reference materials in the form of nano-particulate pressed sulfide powder tablets (PSPTs). Non-matrix-matched external calibration was used to obtain accurate and precise lead isotopic ratios, while mass bias was corrected using a standard-sample bracketing method and a thallium standard solution doping process. In situ analysis of lead isotopic ratios of PSPTs using laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) yielded good external precisions of <0.026% for 207,208 Pb/ 206 Pb and <0.057% for 206,207,208 Pb/ 204 Pb (2RSD). Meanwhile, the standard deviations of results afforded by LA-MC-ICP-MS were better than 0.41‰ for 34 S/ 32 S (2SD). The in situ analytical results of PSPTs were consistent with the values obtained using solution nebulizer MC-ICP-MS, thus demonstrating the reliability and robustness of our analytical protocol. This method can also be used to synthesize different material matrices with homogeneous sulfur and lead isotopes to correct mass bias when using standard-sample bracketing for in situ analysis. [ABSTRACT FROM AUTHOR]

• A new structure with 2.3∼19.59% performance enhancement is proposed based on MO-optimization. • The Double-layer multi-objective optimization algorithm is applied in the convex plate heat exchanger. • PEC and FSP analysis are used to evaluate the heat transfer and flow characteristics. • An experiment platform is designed for performance exploration and verification. The convex plate heat exchanger is one of the new types of plate heat exchangers that have specific functional properties compared to conventional plate heat exchangers, the structural parameters of convex plate heat exchangers are important in affecting the heat transfer performance. In this paper, based on two-layer multi-objective optimization which is aimed at maximum performance evaluation criterion (PEC) and maximum field synergy number (Fc), the heat transfer and flow characteristics of convex plate heat exchanger are investigated experimentally and numerically. The optimization findings are broken down into single factor, response surface, and sensitivity analysis. The optimal results under different objective functions are analyzed and the optimal structural parameters obtained which are the welding hole radius (R) is 5.81 mm, the ellipse radius (L) is 5.02 mm, and the welding hole spacing (P) is 64.00 mm; Compared to the structure before optimization, the size-optimized structure may enhance the temperature differential between the inlet and outflow of the cooling water by less than 8.27%, the heat transfer performance is increased by 20.43%, and the comprehensive performance is improved by 2.3∼19.59%. [ABSTRACT FROM AUTHOR]

This paper is an in-depth look at the problem of removing the blur from a complex motion-blurred star image. Accordingly, a simple yet effective l p ( 0 < p ≤ 1 ) -regularized deblurring method based on stars image intensity is proposed. The model builds on the principle that the intensity of clear star image is in accordance with Laplacian distribution or generalized p Gaussian distribution. Further, two algorithms are introduced to solve the ensuing non-smooth ( p = 1 ) or non-convex ( p < 1 ) constrained optimization problem. Simulations and actual star image restoration experiment are implemented to demonstrate that the centroids extraction accuracy of the proposed method is higher than 0.1 pixel, the running time is 3 to 5 times better than Richardson–Lucy filter or other methods based on image gradient constraint, and the peak signal to noise ratio (PSNR) of recovered star images excel results of several other image deconvolution methods. [ABSTRACT FROM AUTHOR]

Phosphate removal and recovery from wastewater is an effective approach to alleviate eutrophication and overcome the future scarcity of phosphorus. Katoite, a kind of calcium aluminate hydrate, was synthesized and examined as a novel adsorbent to remove phosphate from aqueous solution and recover phosphate as potential slow-release fertilizer. Batch experiments showed that the maximum phosphate adsorption capacity of katoite reached 111.51 mg P/g. Also, a high equilibrium adsorption capacity of 80.14 mg P/g was obtained at the initial concentration of 10 mg P/L. The adsorption could be well described by the Elovich kinetic model and Redlich-Peterson isotherm model. Thermodynamic study suggested that the adsorption was an endothermic process and occurred favorably and spontaneously. Moreover, the adsorption was almost independent of the ionic strength and showed high selectivity for phosphate in solutions containing common coexisting anions. The phosphate adsorption on katoite could be attributed to inner-sphere complexation and surface precipitation, which were further suggested by the SEM-EDS, FTIR and XPS analysis. Desorption experiments results indicated the possible plant availability and successive release property of the phosphate adsorbed on the surface of katoite. Overall, the study suggested that katoite is a promising candidate for phosphate adsorption and subsequent recovery as a slow-release phosphorus fertilizer. [Display omitted] • Maximum adsorption capacity of 111.51 mg P/g was achieved by katoite. • A high selectivity for phosphate was observed in the presence of competing anions. • Phosphate was adsorbed mainly through ligand exchange and surface precipitation. • The phosphate adsorbed on katoite showed possible bioavailability. • Phosphate saturated katoite exhibited successive P release property during 15 days. [ABSTRACT FROM AUTHOR]

Routing protocol is an important topic in the wireless sensor networks. For MultiSink wireless sensor networks, the routing protocol designs and implementations are more difficult due to the structure complexity. The paper deals with the problem of a multiple-dimensional tree routing protocol for multisink wireless sensor networks based on ant colony optimization. The proposed protocol is as follows: (1) listening mechanism is used to establish and maintain multidimensional tree routing topology; (2) taking into consideration hops, packet losses, retransmission, and delay account, a distributed ant colony algorithm is proposed. When nodes select routes in the data transmission, the algorithm is utilized to realize the real-time optimization by coordination between nodes. The simulation results show that the proposed protocol can realize the QoS optimization for multisink wireless sensor networks, and its performance is better than the routing protocol of minimum hop numbers. [ABSTRACT FROM AUTHOR]

In this study, we provide a microsampling method that determines the Cu isotopic composition of copper-bearing minerals using the microdrill sampling and MC-ICP-MS measurement. Eleven different natural copper minerals were sampled with microdrill and analyzed using MC-ICP-MS after digestion for half an hour on a 140 °C hot plate without chromatography. The Cu isotope results were calibrated using the standard sample bracketing combined with NIST 994 Ga as the internal standard. Cu isotope compositions of the same sample processed with chromatography were also determined to verify the accuracy of this method. Results have shown that δ65Cu of all sample solutions with or without chromatography are overlapped and the deviations between them are less than 0.04‰, indicating this method is applicable to most natural copper-bearing minerals. All the microdrill-sampled copper minerals were directly digested without chemical purification, thus potential matrix elements, including metal cations and some anions, still existed in the solutions. The matrix effects of metal cations and anions were systematically investigated in this study. Results have shown that the δ65Cu deviations are less than 0.05‰ within the uncertainty when the concentration ratios of matrix elements Zn, Fe, Ni, Al, Sb, and Co/Cu + S were less than 2, Ti/Cu + S ≤ 0.8, and Mn/Cu + S ≤ 0.5. This method has the merits of saving time and reagents, low background, good accuracy and reliability as well as improved spatial resolution. It is easier to achieve in most isotope laboratories compared to other microsampling methods such as laser ablation method. This study represent determination of δ65Cu of Cu-bearing minerals using microdrills and MC-ICP-MS without chromatography Image 1. • A microsampling procedure of Cu isotope determination was processed using MC-ICP-MS and microdrill without chromatography. • This procedure simplifies the digestion procedure, combines the advantage of high precision of MC-ICP-MS with spatial resolution. Furthermore, there is no needs of matrix matched reference compare to LA-MC-ICP-MS. • Eleven copper bearing minerals were applied to verify the reliability and robustness of our analytical protocol, including native copper, cooper sulfides, carbonates copper chloride. [ABSTRACT FROM AUTHOR]

To enhance the degradation of wheat straw (WS) and corn straw (CS) in rumen fermentation, characterization of degradation and ruminal microorganisms of monosubstrate (WS/CS) groups and a cosubstrate strategy with food waste (FW) group was performed. The cellulose, hemicellulose, and lignin degradation efficiency of WS and CS; soluble chemical oxygen demand; volatile fatty acid yields; and activity of ligninolytic, cellulolytic, and hemicellulolytic enzymes for the cosubstrate group were improved compared with those for the corresponding monosubstrate groups. An accurate and a good of fit of the Weibull kinetic model, decreased crystallinity index values, and characteristic absorbance bands in the Fourier transform-infrared spectra further confirmed that cosubstrate addition with FW decreased the resistance of cellulose and hemicellulose to biodegradation. High-throughput sequencing results suggested that the bacterial diversity in CS rumen fermentation and fungal diversity and richness in WS rumen fermentation were promoted with FW as a cosubstrate. The cosubstrate addition with FW significantly affected the composition of the ruminal bacteria and fungi in rumen fermentation. The relative abundances (RAs) of rumen bacteria were increased in the cosubstrate CS/WS and FW fermentation conditions, and the enhancement of CS degradation with FW supplementation was stronger than that of WS rumen fermentation with FW supplementation. The RAs of the ruminal fungal genera Ustilago and Fusarium were promoted in CS and WS fermentation with FW, respectively. Moreover, the fermentation properties and rumen flora in the FW rumen fermentation also provided some evidence to suggest an enhancement of the cosubstrate strategy compared with the monosubstrate strategy. Image 1 • Food waste (FW) increased alkalinity and improved VFAs yield in rumen fermentation. • Wheat/corn straw (WS/CS) rumen degradation was enhanced by cosubstrate with FW. • Lignocellulases and bacterial diversity in CS and FW fermentation were improved. • Fungal diversity and richness in WS fermentation were promoted with FW addition. [ABSTRACT FROM AUTHOR]

The numerical and experimental data of the helically coiled-twisted trilobal tube (HCTTT) heat exchanger are compared, the results present that, due to more intense secondary flow of the HCTTT caused by the superposition of overall twist and self-twist, region near the center of the HCTTT has higher turbulent kinetic energy, and the region near the wall of the HCTTT is with the better Field synergy Angle. Two evaluation criteria, Performance Evaluation Criteria (PEC) and Filed synergy number (Fc) are introduced to comprehensively evaluate comprehensive performance, the results present that the HCTTT performs better in the Hydrodynamic and thermal performance than that of the helically coiled elliptical tube (HCET), helically coiled plain tube (HCPT) and trilobal tube (HCTT). In addition, compared to the HCPT, the increment ratio on Nusselt number of HCTTT is more than 19%–31%, while the augmentation ratio of flow resistance is up to 24%–38%. The novel correlations proposed in the HCTTT heat exchanger are consistent with the simulation data. [ABSTRACT FROM AUTHOR]

This study presented a chemical protocol for purification of calcium and magnesium from a single aliquot of biological and geological samples. The separation protocol was based on a two-step cation exchange chromatography using DGA resin and AG50W-X12 (200–400 mesh) resin. Calcium fraction was first collected using 0.25 mL of DGA resin, and Mg fraction was then collected using 0.5 mL of AG50W-X12 cation exchange resin. For Ca isotope analysis, the effect of acidity and concentration mismatch as well as the matrix effect were rigorously evaluated using the Neptune Plus MC-ICP-MS with a wet-plasma mode. Based on repeated measurements on BHVO-2 and NIST SRM 1400, the long-term reproducibility was evaluated at 0.08‰ (2SD) for δ44/42Ca 915a. The δ26Mg ratios of the analyzed reference materials varied from −1.22‰ to 0.03‰ with the external precision better than 0.11‰ (2SD). The robustness of the protocol has been validated by replicated analyses of biological and geological standards. Calcium and magnesium isotopic ratios of all reference materials measured in this study agreed well with previous data within uncertainties. Therefore, the proposed method can be used for simultaneous determination of Ca and Mg isotopic ratios from a single aliquot of biological and geological samples. Image 1 • Purification of calcium and magnesium from a single aliquot of biological and geological samples. • Mg isotopic ratios of GSH-1, GSV-3, NIST SRM 1400, and NISR SRM 1486 were reported for the first time. • The method reduces the amount of acid used, saves time and is more efficient. [ABSTRACT FROM AUTHOR]