Top Zone Research Articles

МИКРОЭЛЕМЕНТНЫЙ СОСТАВ ПОДЗЕМНЫХ ВОД ВЕРХНЕЙ ГИДРОГЕОДИНАМИЧЕСКОЙ ЗОНЫ В БАССЕЙНЕ ВЕРХНЕЙ ОБИ КАК ФАКТОР ФОРМИРОВАНИЯ ИХ ЭКОЛОГО-ГЕОХИМИЧЕСКОГО СОСТОЯНИЯ

Актуальность исследованияопределяется необходимостью учета наиболее полной информации о химическом составе подземных вод при их подготовке для хозяйственно-питьевого использования. Ранее для бассейна Верхней Оби были получены данные преимущественно по макрокомпонентному составу, перманганатной окисляемости, биогенным элементам и содержаниям ограниченного количества микроэлементов, что не позволяло объективно оценить возможное влияние региональных факторов с токсикологическим и санитарно-токсикологическим лимитирующими признаками воздействия. Цель исследованиязаключается в оценке микроэлементного состава подземных вод эксплуатируемых горизонтов верхней гидрогеодинамической зоны в бассейне Верхней Оби (на территории Алтае-Саянской гидрогеологической складчатой областии примыкающих к ней районов Западно-Сибирского артезианского бассейна). Объекты: подземные воды, используемые для питьевого водоснабжения в бассейне Верхней Оби (территории Республики Алтай, Алтайского края, Новосибирской, Кемеровской и Томской областей). Методы: современные методы определения химического состава подземных вод, включая: в 2019 г. – масс-спектрометрический метод с индуктивно связанной плазмой (ICP MS); в 1998 г. – нейтронно-активационный анализ; статистические методы. Результаты. Выполнен анализ химического состава подземных вод, используемых для хозяйственно-питьевого водоснабжения в бассейне Верхней Оби. Полученные результатыпозволяют существенно расширить представление о микроэлементном составе подземных вод рассматриваемой территории. Показано, что уровень содержания большинства изученных микроэлементов меньше установленных в Российской Федерации нормативов качества. Однако показатель аддитивного воздействия (сумма отношений фактических и предельно-допустимых концентраций веществ 1–2 классов опасности SС1-2/ПДК) часто больше единицы, что указывает на потенциальное токсичное воздействие на здоровье при использовании подземных вод без соответствующей водоподготовки. Наиболее высокиезначения SС1–2/ПДК (более 5) отмечены для подземных вод в Алтайском крае и Республике Алтай, в селах Хабазино, Онгудай и Тальменка (водосборы притоков Оби – рек Алей, Катунь и Чумыш, соответственно). С учетом установленных рудопроявлений и характера концентрирования в подземных водах региона парагенетических ассоциаций химических элементовсделано предположение о существенном вкладе природных факторов в формирование наблюдаемого уровня содержания многих микроэлементов.

Paternal exposure to a common herbicide alters the behavior and serotonergic system of zebrafish offspring.

Increasingly, studies are revealing that endocrine disrupting chemicals (EDCs) can alter animal behavior. Early life exposure to EDCs may permanently alter phenotypes through to adulthood. In addition, the effects of EDCs may not be isolated to a single generation − offspring may indirectly be impacted, via non-genetic processes. Here, we analyzed the effects of paternal atrazine exposure on behavioral traits (distance moved, exploration, bottom-dwelling time, latency to enter the top zone, and interaction with a mirror) and whole-brain mRNA of genes involved in the serotonergic system regulation (slc6a4a, slc6a4b, htr1Aa, htr1B, htr2B) of zebrafish (Danio rerio). F0 male zebraFIsh were exposed to atrazine at 0.3, 3 or 30 part per billion (ppb) during early juvenile development, the behavior of F1 progeny was tested at adulthood, and the effect of 0.3 ppb atrazine treatment on mRNA transcription was quantified. Paternal exposure to atrazine significantly reduced interactions with a mirror (a proxy for aggression) and altered the latency to enter the top zone of a tank in unexposed F1 offspring. Bottom-dwelling time (a proxy for anxiety) also appeared to be somewhat affected, and activity (distance moved) was reduced in the context of aggression. slc6a4a and htr1Aa mRNA transcript levels were found to correlate positively with anxiety levels in controls, but we found that this relationship was disrupted in the 0.3 ppb atrazine treatment group. Overall, paternal atrazine exposure resulted in alterations across a variety of behavioral traits and showed signs of serotonergic system dysregulation, demonstrating intergenerational effects. Further research is needed to explore transgenerational effects on behavior and possible mechanisms underpinning behavioral effects.

Treated versus Untreated Aggregate Bases for Flexible Pavements: Nationwide Comparative Case Study

Aggregates constitute a major part of pavement construction. The strength, durability, and quality of the aggregate affects the overall performance of the pavement structure. Materials sourced near a construction site do not always meet the strength required for pavement construction, however, and haulage of aggregates of the required quality is often costly. For better use of locally available materials, stabilizing agents such as lime, cement, asphalt cement, and fly ash are often used to enhance the strength of the local aggregates. Pavement performance is influenced by both the structure itself and the layer materials present in it. The stiffness of the base layer, for instance, influences the tensile strain in the asphalt layer and compressive strains in the subgrade soil. The tensile strains at the bottom of the asphalt layer and compressive strains in the top zone of the subgrade soils are the main response components affecting fatigue cracking and rutting, respectively. In this study, field performance [rutting, cracking, and roughness measured in relation to the International Roughness Index (IRI)] of pavement sections with treated and untreated base layers were compared to determine the effects of stabilizing agents. In relation to fatigue cracking and pavement surface roughness, the treated sections outperformed the untreated sections. The average values of all three distresses showed better performance for the treated base layer sections with fatigue cracking averaging 2.2 times lower than the untreated sections. The combined rutting and IRI of the treated base layer sections averaged about 0.10 in. and 1.4 times lower than those of the untreated base layer sections, respectively.

Failure analysis of an exploded large-capacity liquid storage tank using finite element analysis

In case of liquid storage tank has been designed regardless of international standards and there is little interest with its operating conditions, it may lead to fully or partially failure. This paper has studied a failure of Toluene storage tanks with different capacities. Toluene is a liquid aromatic hydrocarbon C7H8 which is toxic, flammable and may cause boiled liquid expanded vapor explosions (BLEVE). Failure analysis was performed to determine the root causes of toluene storage tank failure as well as corrosion influence. Axisymmetric finite Element analysis (FEA) was performed for fillet welding of tank roof and top shell zone to develop a relation between weld electrode size and tank diameter at each type of weld electrode to determine the main framework of roof to top shell welding process. Also, to develop a relation between tank diameter and maximum stresses that resulted at every amount of vapor pressure according to maximum von-Mises stress theory. The optimum roof to top shell welding size is obtained through the circumference welding path. The results of analysis allowed us to redesign the tank according to API 650 and to express the recommendations for toluene storage tanks operation.

Flexural behavior of precast UHPC beam with prestressed bolted hybrid joint

Ultra-high performance concrete (UHPC) is suitable for precast and assembled bridges due to its unique characteristics. Therefore, an efficient, safe, and durable joint connection that fits between the precast UHPC beam segments is of crucial importance. In existing conventional prestressed joints, a potential safety hazard exists because steel strands corrode under long-term detrimental environmental conditions. To address this issue, a prestressed bolted hybrid joint was proposed in this study. Eight precast UHPC beams with different types of joints were constructed. Experimental tests were conducted to examine the flexural behavior and load-bearing mechanism of the prestressed bolted hybrid joint, prestressed joint, and bolted joint. The flexural capacity, characteristic loading values, deformation characteristics, and the failure modes of the three types of joints were investigated and the influences of the bolts and epoxy resin adhesive on the flexural capacity of the joints were also discussed. The test results showed that the failure of the hybrid joint was characterized by the local crushing of the UHPC at the top compression zone together with shearing off of some of the bolts. The flexural capacity of the hybrid joint was significantly improved and was 46.8–60.3% higher than that of the conventional prestressed joint. The overall flexural capacity of the hybrid joint can be divided into two parts, the contributions of the prestressed UHPC joint and bolted connection. The epoxy resin adhesive had little effect on the slip resistance of the bolted joint; however, its bonding effect increased the cracking moment and flexural capacity of the joint by 16.5–29% and 11.5–21.8%, respectively. Besides, due to the strengthening effect of the bolted steel plates and the prestressing, the overall stiffness of the UHPC beam with the hybrid joint was significantly higher than that of the prestressed joint and the bolted joint after joint opening. Based on the test results, a computational method was proposed for calculating the slip moment, joint-opening moment, and ultimate flexural capacity of the prestressed bolted hybrid joint and the prestressed joint, and the feasibility of the hybrid joint was verified.

Microstructure evolution and mechanical properties of laser metal deposition of Invar 36 alloy

Laser metal deposition (LMD) technology was used to fabricate single-track-multi-layers samples using Invar 36 alloy powder by two different deposition patterns: one-way laser scanning pattern and back and forth laser scanning pattern. The microstructure characteristics, grain morphology, formation mechanism and mechanical properties of the samples fabricated in two different deposition patterns were systematically investigated. It was shown that there was a thin layer of equiaxed grains in the top zone, an alternative arrayed grain morphology of columnar and cellular grains in the middle and periodic circular growth of small columnar grains at the bottom, which was generated by different temperature gradient in different location. The crystal orientation of columnar grains was distinct due to different deposition patterns. X-ray diffraction (XRD) and Energy Dispersive Spectrometer (EDS) showed that the deposited specimen was composed of austenite-single phase. Samples built by back and forth laser scanning pattern showed higher microhardness and tensile strength but lower elongation compared with samples built by one-way pattern, the horizontally built sample showed higher Ultimate tensile strength and yield strength but lower elongation compared with vertically built sample in the same laser scanning pattern. Laser metal deposited Invar 36 showed more excellent mechanical properties compared to the forged and casted counterparts.

Bruise Patterns of Fresh Market Apples Caused by Fruit-to-Fruit Impact

Comprehensive understanding of bruise damage caused by apple-to-apple impacts is beneficial to design a low-impact fruit capturing mechanism for mass (shake-and-catch) harvesting, as well as to design other fruit handling devices. This study quantified the bruising severity in ‘Jazz’ apples induced by different levels of impact upon various fruit surface locations. Impact experiments were carried out to analyze bruising patterns in three zones in a fruit surface, i.e., middle/cheek-to-top/stem, middle-to-middle and middle-to-bottom/calyx. Moving fruit and stationary fruit were impacted using a pendulum-type test device, and an equivalent drop height of fruit was calculated to provide a more practical measure for designing a catching surface. In each impact zone, seven different levels of impacts were applied respectively at seven different locations on the fruit surface. Those locations were evenly distributed along the circumferential direction in each of the three zones, and moving fruit was replaced after each impact test. The United States Department of Agriculture (USDA) standard was then used to estimate percentages of fruit in the Extra Fancy Class 1 (no bruising), Extra Fancy (a bruising area diameter ≤ 12.7 mm) and Fresh Market (a bruising area diameter ≤ 19 mm) grades. Results showed that fruit bruising severity increased in a non-linear manner with increasing drop height. It was also found that there existed significant differences in fruit bruising severity between stationary and moving fruit under different fruit-to-fruit impact zones. The bottom zone showed the least bruising sensitivity, followed by the middle zone which was statistically similar to the same in the top zone. The results suggested that the free drop height need to be <3 cm to keep from fruit bruising caused by apple-to-apple impact at a negligible level for ‘Jazz’ apples.

Failure Analysis of an Exploded Large-Capacity Liquid Storage Tank Using Finite Element Analysis

In case of liquid storage tank has been designed regardless of international standards and there is little interest with its operating conditions, it may lead to fully or partially failure. This paper has studied a failure of Toluene storage tanks with different capacities. Toluene is a liquid aromatic hydrocarbon C7H8 which is toxic, flammable and may cause boiled liquid expanded vapor explosions (BLEVE). Failure analysis was performed to determine the root causes of toluene storage tank failure as well as corrosion influence. Axisymmetric finite Element analysis (FEA) was performed for fillet welding of tank roof and top shell zone to develop a relation between weld electrode size and tank diameter at each type of weld electrode to determine the main framework of roof to top shell welding process. Also, to develop a relation between tank diameter and maximum stresses that resulted at every amount of vapor pressure according to maximum von-Mises stress theory. The optimum roof to top shell welding size is obtained through the circumference welding path. The results of analysis allowed us to redesign the tank according to API 650 and to express the recommendations for toluene storage tanks operation.

Potential application of the CO<SUB align="right">2-assisted gravity drainage process in a mature oil field: insights from reservoir-scale EOR evaluation

The gas-assisted gravity drainage (GAGD) process was implemented through continuous and cyclic immiscible injection to enhance the recovery of bypassed oil in the upper sandstone reservoir in the South Rumaila oil field, located in Southern Iraq. A compositional simulation model was constructed for the carbon dioxide (CO2) flooding evaluation through the GAGD process implementations. After achieving history matching, 20 vertical CO2 injectors and 11 horizontal oil producers were placed in top reservoir and oil zone, respectively. The immiscible CO2-GAGD performance was evaluated for 10 years of future prediction. The continuous and cyclic immiscible GAGD cases resulted in reaching recovery factor of 14.5% and 21.3% given the remaining oil, respectively. However, the recovery factor given the remaining oil was 7.6% through primary production by the end of prediction period. Additionally, the obtained amount of oil in 10 years primary production can be produced in only one year by the continuous case and in 8 months by the cyclic case. Consequently, the optimal implementation of the GAGD process is by adopting the cyclic CO2 flooding that efficiently enhance the recovery of bypassed oil. [Received: December 30, 2017; Accepted: December 17, 2018]

Effect of hydraulic fracture closure on the void ratio of proppant particles in coalbed methane reservoir

Fracture closures have direct effects on the void ratio distributions of proppant particles filled in hydraulic fractures and then influence the fluid pathways of coalbed methane (CBM) within those fractures. In this paper, a numerical simulation method was used to investigate the void ratio distributions of proppant-filled fracture under different compression amounts of 0%, 5%, 10%, 15% and 20%. The results showed that the void ratio distributions had exhibited an inverted “U” shape, with a trend of decreasing first, followed by remaining constant, and then increasing from the bottom to the top of the fracture, which could be divided into three zones: bottom loose zone (BLZ), middle compaction zone (MCZ) and top loose zone (TLZ). At the same compression, the small coordination numbers in the BLZ and TLZ had accounted for a larger proportion, and the average coordination numbers and void ratios in the two zones were 0.8–0.9 and 1.3 times than those in the MCZ, respectively. In addition, the proportion of the large coordination numbers in the different layers had increased, and the layered average coordination numbers had increased linearly, which had resulted in the layered void ratios decreasing linearly with the increases in the compression amounts.

Determination of destructive forces in a rod-cable arch

The aim of research - comparison the results of the experimental data with the computer modeling the work of the strengthened brick-cable arch. Methods. Experimental and theoretical methods of research. Results. Firstly, the tests on a small desktop models were performed, for the determination the nature of destruction of the construction. During them, it was discovered, that the arch crash is taking place because of the splitting the small size timber bricks, or as the result of the breaking its steel strengthening elements. Further, the computer model of the construction was created with the help of physically and geometrically nonlinear finite elements at LIRA-SAPR PC. The generated model was load by a concentrated force at its top zone, the same one, as it had been during the experiments before. On the results of the calculation, the maximum deformation was received, which are different from the experimental one on a value less then 10%, what suggests the nearness the computer model to the real construction. The highest compressive strengths of the arch and the largest stretching forces of its steel bands were determined during the further analysis of the model. Maximum splitting and stretching forces also were calculated theoretically, according to the formulas of SP 64.13330.2017 and SP 20.13330.2016. It was determined that the timber bricks have more than 7 times reserve of strength, and the steel bands over them - only times, and during the growth of external force, the arch will crash because of its steel sprengel bands breakage. By the results of the research, the calculation algorithm of such kind constructions was generated, at the base of LIRA-SAPR PC. It was recommended first, to determine deformation of the strengthened brick-cable arch, with further checking the timber elements for splitting and steel sprengel elements for maximum permissible stretching. The problem of stability the flat form of deformation for the brickcable arch are the same as for the glued one, because of the tight connection the timber bricks, with elimination their exit from the frontal plane.

Additive/subtractive hybrid manufacturing of 316L stainless steel powder: Densification, microhardness and residual stress

316L stainless steel specimens were manufactured by additive/subtractive hybrid manufacturing (ASHM). The densification level, mi-crostructure, microhardness and residual stress characterization in the different zones of the part were investigated. The density was determined by the Archimedes method, and the density measurement was divided into three regions, namely, the bottom, middle and top zones. The results show that the middle zone has a much smoother melting surface and that a relative density of nearly 100 % was achieved for the part in this study. The hardness profiles at room temperature, along the width and height directions of the cross-section of the top and bottom zones, were also studied. The residual stress was evaluated by X-ray diffraction (XRD) for the 316L SS specimen fabricated by the ASHM process, and it was compared with a specimen manufactured by the additive laser directed energy deposition (DED) process. The results show that the top and bottom zones exhibit tensile stress, and compressive stress occurs in the middle area. Moreover, the residual stress of ASHM shows a slightly smaller trend than that of the simplex DED due to the stress relaxation of the subsequent subtractive milling. These results may offer guidance for ASHM-fabricated 316L parts.

How toxic is a non-toxic nanomaterial: Behaviour as an indicator of effect in Danio rerio exposed to nanogold

Gold nanoparticles are used as drug delivery vectors based on the assumption that they have low toxicity. Literature has, however, produced conflicting results over the last few years. As such, this study aimed to investigate the toxicological effects of nanogold (nAu) on several indicators that range from subcellular to whole-organism level. Gene regulation, changes in oxidative stress biomarkers and swimming performance were assessed in Danio rerio (zebrafish) following exposures to nAu. Adult zebrafish were exposed in vivo to nAu for 96 h and swimming performance measured post-exposure. Liver tissue was collected for DNA microarray and Real-Time Polymerase Chain Reactions (RT-PCR) analyses to determine changes in gene expression (catalase, superoxide dismutase and metallothioneins) and protein biomarker analyses (catalase, superoxide dismutase, acetylcholine esterase, malondialdehyde, cellular energy allocation and metallothionein) were performed on whole-body samples. Swimming behaviour was assessed in 1.1 L Tecniplast™ tanks for a period of six hours and videos were analysed using Noldus EthoVision software. Critical swimming speed was measured in a Loligo® swimming tunnel. The DNA microarray revealed that fish exposed to 20 mg/L differed most from the control group. At 20 mg/L there was a significant increase in gene expression for all genes analysed but this didn’t translate to significant responses in protein biomarker levels except for an increase in protein carbonyl formation. The behaviour results demonstrated significant changes in distance moved, swimming speed, acceleration bouts, zone alterations and time spent within the top zone – responses that are usually observed in fish responding to toxicological stress. Furthermore, the critical swimming speed of exposed fish was decreased significantly compared to the control. Since swimming performance and social interaction among zebrafish is essential to their survival, whole-organism behaviour that suggests a toxicological response after exposure to nAu is in agreement with the genetic responses measured in this study.

Rapid prediction of real-time thermal characteristics, solidification parameters and microstructure in laser directed energy deposition (powder-fed additive manufacturing)

The localized thermal characteristics, solidification parameters and the corresponding microstructure depend highly on the process parameters in the laser powder-fed additive manufacturing (LPF-AM) process. However, undesirable and inconsistent microstructure may potentially be induced due to the environmental disturbances or improper setting of process parameters. This research correlates the process parameters to the localized transient thermal characteristics, i.e. temperature and cooling rate, and solidification parameters, namely thermal gradient (G) and solidification rate (R) for rapid prediction of the microstructural evolution. The built correlation can also be used for parameter optimization and could be potentially employed for in-situ microstructural control. Firstly, the thermal characteristics and the solidification parameters were resolved from a three-dimensional analytical thermal model that couples the powder mass flow and the laser heat flux. Subsequently, the calculated solidification parameters were combined with the substructure scale solutions for microstructure prediction with respect to the solidification map. In the end, experiments of LPF-AM were conducted with stainless steel 316L (SS 316L) and Inconel 625 powders to validate the built correlation. It was noticed that the calculated real-time melt pool peak temperatures match well with the experimental results at different laser scanning speeds and diverse energy densities in the SS 316L deposition. The predicted microstructural evolutions show reasonable agreement with the experimental observations for both SS 316L and Inconel 625 depositions under different scanning speeds. In addition, it was found that the combination of a higher scanning speed with a lower laser power results in a finer microstructure, but the combinations should be kept within the melt pool temperature thresholds for effective deposition. Moreover, the G × R values increase from the bottom to the top of the melt pool bead, leading to a finer microstructure at the top zone for both SS 316L (5.5 μm average primary dendrite arm spacing) and Inconel 625 (3 μm average secondary dendrite arm spacing) deposits. On the contrary, the G/R values decrease from the bottom to the top of the melt pool bead, which in turn, give rise to the gradual transition of the substructure morphology from columnar dendritic to equiaxed dendritic for the Inconel 625 deposits.

Microstructure and mechanical properties of laser solid formed 30Cr–Mn–Si–Ni–2A ultra-high-strength steel

ABSTRACTMicrostructure and mechanical properties of laser solid formed 30Cr–Mn–Si–Ni–2A steel are investigated. The deposits consist of epitaxial columnar grains, equiaxed grains or direction changed dendrites can be observed in the bulk specimens. The microstructure at the bottom of deposits is mainly composed of tempered martensite; the middle to top zone of the deposits are characterised by martensite and bainite. With the increasing of deposition height, the volume fraction of bainite increases, the size of martensite laths increases but its volume fraction decreases. The microhardness shows a decrease from the bottom zone to the middle–upper zone, and then a significant increase at the top of the deposits. Anisotropic and unevenly distributed tensile properties are observed for the deposits. Samples after heat treatment demonstrate tensile strength of 1720 MPa and elongation rate of 8.7%.

LOAD-CARRYING CAPACITY INCREASE OF ARCH-TYPE TIMBER ROOF

Possibility to increase load-carrying capacity of arch-type timber roof of multifunctional public building with the span equal to 60 m was analysed. Three-hinged segment arches with the rectangular glued cross-sections are considered as the main load-carrying structures in the transversal direction. Freely supported purlins with the massive rectangular cross-sections are considered as the main load-carrying structures in the longitudinal direction. The dependences between height of the arches, it bays and distances between the bracing members strengthening top and bottom zone of the arches cross-sections so as relative materials consumption and specific load-carrying capacity of the arches were obtained as the second power polynomial equations. Height of the arches and it bay changes within the limits from 10 to 30 and from 2 to 9 m, correspondingly. The distances between the bracing members strengthening top and bottom zone of the arches changes within the limits from 2 till 10 and from 4 till 16 m, correspondingly. The arch-type timber roof was considered under the action of the load combination which include structural dead weight, drifted and undrifted snow loads and wind loads. The relative materials consumption of the arches was determined as a relation between the dead weight of the arch to it span and changes within the limits from 24 till 114 kg/m. Glued and solid timber with strength classes GL24h and C24 are considered as materials of arches and purlins, correspondingly. The specific load-carrying capacity of the arches was determined as a relation between load –carrying capacity of the arche and volume of structural materials. Specific load-carrying capacity of the arches changes within the limits from 0.23 till 0.83 kN/m/t in the case, if purlins are taken into account. It was shown, that the rational from the point of view of materials consumption and specific load-carrying capacity height of the arche, it bays so as the distances between the bracing members strengthening top and bottom zone of the arches are equal to 15, 7.5, 5 and 15 m, correspondingly. Corresponding values of relative materials consumption and specific load-carrying capacity are equal to 24 and 0.23 kN/m/t. The depth and width of the arche cross-section were equal to 1617 and 318 mm, correspondingly. It was shown, that strengthening of the arches cross-section by the steel bars of strength class B500 and carbon fibre reinforced plastic tape Sika Crbo Dur S512 enables to increase load-carrying capacity of the arche by 10.20 and 9.48%, correspondingly. But common use of the steel bars together with the carbon fibre reinforced plastic tapes enables to increase load-carrying capacity of the arche by 18.89%.

Glyphosate- and Fipronil-Based Agrochemicals and Their Mixtures Change Zebrafish Behavior

Environmental contamination caused by the human occupancy and economic activities that generate a wide range of contaminated effluents that reach natural water resources, is a current reality. Residues of agrichemicals used in plant production were detected in different environments and in different countries. Among these agrochemicals, we studied a glyphosate-based herbicide (GBH), a fipronil-based insecticide (FBI), and their mixtures (GBH + FBI). Zebrafish exposed to 3 and 5mg/L of GBH spend more time in the top zone and less time in the bottom zone. Fish exposed to 0.009 and 0.018mg/L of FBI spent less time in the bottom zone, whereas zebrafish exposed to the three GBH + FBI mixtures spend more time in the top zone compared with unexposed control fish. This clear anxiolytic pattern, in an environmental context, can directly impair the ability of fish to avoid or evade predators. We concluded that both glyphosate-based herbicide and fipronil-based insecticide and their mixtures alter zebrafish behavior, which may result in significant repercussions on the maintenance of the species as well as on the food chain and the ecosystem.

EYE ON CHINA

China-Germany sci-tech cooperation continue to bring more opportunities. Study reveals mechanism behind ginger’s warming effect on body. Doctors in Guangzhou conduct 5G-assisted remote ultrasound scan. China proposes major changes to pharmaceutical regulations. Hangzhou attracts RMB1.5 billion investments in bio-pharmaceutical projects. Genetic testing encouraged to prevent ovarian cancer. New technology enables large-scale production of artemisinin for malaria. Shanghai wants to develop top health innovation zone. New synthetic biology research center launched in Shanghai. Chinese scientists suggest new thoughts in lupus treatment.

The early Paleozoic Huangtupo VMS Cu—Zn deposit in Kalatag, Eastern Tianshan: Implications from geochemistry and zircon U—Pb geochronology of volcanic host rocks

The Tianshan in China forms the southern part of the Central Asian Orogenic Belt (CAOB) and also hosts important polymetallic resources. Here we investigate the Huangtupo medium–size copper–zinc deposit, located in the central part of the Kalatag copper Polymetallic Belt with a view to evaluate the nature and genesis of the early Paleozoic volcanogenic massive sulfide (VMS) Cu—Zn deposits. This deposit is correlated to intermediate–felsic volcano–sedimentary sequences of the early Paleozoic Daliugou Formation which are mainly composed of andesite, dacite, and rhyolite with minor basalt, as well as their pyroclastic equivalents. The ore bodies are hosted in the contact zone between andesitic volcanic breccia and tuff representing an eruptive hiatus between the two volcanic cycles with massive sulphide lens at the top and stockwork zone at lower part of the Daliugou Formation. We report new zircon U—Pb data, major and trace element geochemistry and Sr—Nd isotopes from the andesite, dacite and andesitic tuff in the Huangtupo deposit. Zircon from the dacite and the andesite occurring above the ore bodies yield and age of 440.1 ± 1.2 Ma and 439.7 ± 0.95 Ma, and that from the andesitic tuff in footwall shows and age of 442.0 ± 1.1 Ma. All samples show typical geochemical signatures of subduction–related calc–alkaline magmas with slight enrichment in LILE and LREE but depletion in Nb and Ti content relative to primitive mantle. The andesites are characterized by high MgO (7.6–10.8 wt%) contents and Mg# values (64–72) with low Sr/Y and La/Yb ratios, belonging to sanukite. Both dacite and tuff have low MgO (<2.5 wt%) and Al2O3 content (15–16.4 and 11.3–15.3 wt%) with Eu negative anomalies (Eu/Eu* = 0.71–0.75 and 0.44–0.6), showing their low–MgO affinity. All the volcanic rocks display similar Nd and Sr isotopic signature, with εNd(t) of 6.5 to 7.3 and moderately high (87Sr/86Sr)i ratios of 0.705274 to 0.706977. The geochemical characteristics and regional geology indicate that these volcanic rocks were formed in an intra–oceanic arc during southward subduction of the oceanic lithosphere in the northern part of the Eastern Tianshan. They were most likely derived from the partial melting of the mantle wedge with input and interaction with subducted–related melts and/or fluids. We also propose that the Huangtupo VMS deposit is analogous to Kuroko type VMS deposits developed within intra–oceanic rift.

Effect of scanning speed on the solidification process of Al2O3/GdAlO3/ZrO2 eutectic ceramics in a single track by selective laser melting

Abstract Al2O3/GdAlO3/ZrO2 ternary eutectic ceramics with fine microstructure were directly fabricated from mixed pure ceramic powders by selective laser melting. The specimen forming quality, molten pool morphology and microstructure characteristic were investigated as functions of scanning speed. Solidification defects such as cracks and pores were effectively suppressed when the scanning speed was 12 mm/min. The relative density of the as-solidified eutectic specimens decreased from 98.7% to 95.7% with increasing the scanning speed up to 48 mm/min. The melting in this study was governed by conduction mode, leading to a decrease tendency of both melting width and depth with the increase of the scanning speed. Different from ordinary cognition, the eutectic spacing in top zone of the molten pool first decreased and then increased with increasing the scanning speed from 6 mm/min to 48 mm/min. The transition point appeared at 12 mm/min, where the dominant factor affecting the solidification rate changed from the scanning speed to the value of the angle between microstructure growth direction and laser scanning direction.