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Students' informal science learning experiences are believed to strongly influence their attitudes toward science and their abilities in the subject. Factors associated with students' informal science learning experiences include family socioeconomic status and perceived family support. However, little is known about whether perceived family support for children's formal and informal science learning differs significantly. The present study filled this gap by exploring how students' perceived family support for formal/ informal science learning affected the link between their socioeconomic status and their experiences of informal science learning. Survey data were collected from 486 Chinese grade 4-6 primary school students. Structural equation modeling demonstrated that the students' socioeconomic status and their informal science learning experiences were significantly and positively correlated. This association was chain-mediated through two categories of perceived family support. Specifically, students' socioeconomic status affected their informal science learning experiences through the separate mediating role of family support for formal science learning and the sequential mediation of perceived family support for formal and informal science learning. These results uncover the role that family support plays in students' science education; accordingly, parents are encouraged to help their children learn science both formally and informally.

Objective: To realize the full automation of shrimp deep processing. Methods: Based on analysis of physical characteristics of northern and southern American shrimps, according to the feature of the center of gravity located between the thickest part of the shrimp body and the tail of the shrimp, an automatic orientation and grading device of shrimp head and tail was designed. Taking the clip angle between directional roller shaft line and horizontal line and the speed of directional roller as testing factors, the directional components were tested. Results: When the directional roller speed was 60 r/min, and the angle between axis line and horizontal line was 15°, the falling speed of shrimp was even and stable with high directional rate, which was benefit for subsequent grading transportation. Conclusion: The device realizes the shrimp head and tail positioning and classification, which is conducive to the full automation of shrimp processing.

Equid alphaherpesvirus 1 (EHV-1) has been linked to the emergence of neurological disorders, with the horse racing industry experiencing significant impacts from outbreaks of equine herpesvirus myeloencephalopathy (EHM). Building robust immune memory before pathogen exposure enables rapid recognition and elimination, preventing infection. This is crucial for effectively managing EHV-1. Removing neuropathogenic factors and immune evasion genes to develop live attenuated vaccines appears to be a successful strategy for EHV-1 vaccines. We created mutant viruses without ORF38 and ORF37/38 and validated their neuropathogenicity and immunogenicity in hamsters. The ∆ORF38 strain caused brain tissue damage at high doses, whereas the ∆ORF37/38 strain did not. Dexamethasone was used to confirm latent herpesvirus infection and reactivation. Dexamethasone injection increased viral DNA load in the brains of hamsters infected with the parental and ∆ORF38 strains, but not in those infected with the ∆ORF37/38 strain. Immunizing hamsters intranasally with the ∆ORF37/38 strain as a live vaccine produced a stronger immune response compared to the ∆ORF38 strain at the same dose. The hamsters demonstrated effective protection against a lethal challenge with the parental strain. This suggests that the deletion of ORF37/38 may effectively inhibit latent viral infection, reduce the neuropathogenicity of EHV-1, and induce a protective immune response. [ABSTRACT FROM AUTHOR]

The micro nonmetallic inclusion and oxygen content in steel significantly affect its performance, and removing the inclusion involves a difficult process. A nitrogen absorption and release method has been developed with which nonmetallic inclusions and T[O] were efficiently removed from bearing steel. However, the inclusions in bearing steel are highly different from those in Si-Mn deoxidized steel, and the effect of the nitrogen absorption and release method on the Si-Mn deoxidized steel remains unclear. Based on this, a thermal experiment was carried out in this study to investigate the removal of nonmetallic inclusions from Si-Mn deoxidized steel by nitrogen absorption and release method, where SWRH82B hot rolled wire coil was used as the experimental steel, and five groups of increasing nitrogen pressure (0.02, 0.035, 0.05, 0.065 and 0.08 MPa) were set up. The results show that for all groups, the T[O] and T[N] in the steel reduce to below 1×10-5 and 5×10-6, respectively, after the molten steel is subjected to 20 min of increasing nitrogen and 30 min of vacuum treatment. The lowest T[O] and T[N] in the steel is 4×10-6 and 2×10-6, respectively, and the inclusion removal rates for all the groups are more than 40%. The T[O] removal rates for all the groups are more than 78%.This result proves that nitrogen absorption and release method is efficient in removing inclusions and T[O] in Si-Mn deoxidized steel. Furthermore, the removal rate of inclusion and T[O] in the steel increases with the nitrogen pressure. When the nitrogen pressure is 0.08 MPa, the removal rates of T[O] and the inclusions are 89.2% and 87.4%, respectively. Theoretical analysis shows that the nucleation rate, number, and density of bubble in molten steel increase with pressure, the efficiency of the inclusions removal can be promoted.

The fluid flow pattern and free surface fluctuation in a mold profoundly influence both molten steel solidification and molten slag thermodynamics behavior in the continuous casting process. In addition, the fluid flow and surface fluctuation behaviors are important factors of inclusions floatation, meniscus hook formation, and shear layer instability that affect the slab quality. In this work, a 0.6-scale water model of slab mold was built according to a 220 mm×1800 mm actual mold from a Chinese steel plant to investigate the fluid field and free surface fluctuation during the continuous casting process. The characters of fluid flow were studied with particle image velocimetry (PIV) in different submerged entry nozzle (SEN) conditions, including SEN outlet angle, SEN bottom structure, and SEN submerged depth. Simultaneously, the fluctuation behaviors of the mold free surface were monitored using wave-amplitude sensors and analyzed using the F value. The findings show that there are shear flow with tilt down velocity vectors appearing near the one-fourth wide face position of the mold free surface, and some irregular vortexes are detected near the SEN position. In addition, the results show that increasing the SEN outlet angle and submerged depth can expend the up-recirculation flow domain and intensify its buffer action; therefore, the velocity of mold liquid surface decreases. However, changing the SEN bottom structure has negligible effect on fluid flow velocity at the position of one-fourth wide face of the mold free surface, although it can reduce the turbulent kinetic energy of the steel jet. Besides, the variation of surface fluctuate amplitude corresponds to the F value well, and the optimal F, which helps to reduce and avoid the possibility of mold slag entrapment can be obtained in the conditions of SEN outlet angles of 15° and 20° and submerged depths of 135 and 145 mm, respectively.

The morphology, composition, and number of inclusions in Fe-Mn-C(-Al) twining-induced plasticity (TWIP) steels were investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and an automated program called "INCAFeature". The characteristics of the inclusions in four TWIP steels with different Al contents (0.002% -1.590%) as well as the influence of Al content on the precipitation of AlN inclusions were investigated. In addition, systematic thermodynamics calculations of AlN formed in TWIP steel were carried out using the appropriate thermodynamic data for high-Mn-Al TWIP steel. The results show that AlN would begin to precipitate and locally precipitate around the MnS(Se) -Al2O3 inclusions when the Al content in the steel reaches 0.75%. The thermodynamics calculations show that AlN could already form in the liquid TWIP steel at an Al content of 1.07%. Then, AlN would locally precipitate around the MnS(Se) inclusions, thus forming MnS(Se) -AlN aggregates. When the Al content increases to 1.59%, the precipitation temperature of AlN is 42℃ higher than the liquidus temperature of the TWIP steel. Furthermore, precipitated AlN inclusions in the liquid TWIP steel could act as heterogeneous nuclei for MnS(Se) inclusions, thus forming MnS(Se) -AlN inclusions. Moreover, according to the thermodynamics calculation, the lowest N content for AlN formation in the liquid Fe-18.21% Mn-0.64% C-1.59% Al steel is just 0.0043%. Therefore, the N content should be kept as low as possible to avoid the formation of excessive AlN inclusions during melting of Fe-Mn-C(-Al) TWIP steel.

Alclad and unclad 2E12 aerospace aluminum alloy were treated by sulfuric acid anodic oxidation. The effects of alclad layer and anodizing time on the anodization behaviour and corrosion resistance of anodic oxide layer on 2E12 aluminum alloy were studied. Surface and cross-section morphology of anodic oxide films were observed by scanning electron microscopy. The electrochemical properties of anodic oxide films were analyzed by potentiodynamic polarization curve and electrochemical impedance spectroscopy. The results show that the protective anodic oxide layers are formed on alclad and unclad 2E12 aluminum alloy. The film thickness increases with anodizing time extending. The copper rich second phase particles lead to more cavity defects and even micro cracks on anodic oxide films of unclad 2E12 aluminum alloy. The anodic oxide films on alclad 2E12 aluminum alloy are thicker and have fewer cavity defects, resulting in better corrosion resistance. The films obtained after 30min and 45min anodic oxidation treatment exhibit lower corrosion current and higher impedance of the porous layer than other anodizing time.

A series of bending fretting fatigue tests of 18CrNiMo7-6 alloy steel were carried out, the bending fretting fatigue S-N curve was built up, and an analysis was made on the test results. The results show that, the S-N curve of 18CrNiMo7-6 alloy steel presents a shape of "ε" curve, which is different from the medium carbon steel, and also different from the plain bending fatigue. With the increase of the bending fatigue stress, the fretting regime transforms from partial slip regime to mixed regime and slip regime. The wear mechanisms of fretting damage zones mainly are delaminated, abrasive wear and oxidative wear. In the mixed regime, the cracks are easy to initiate and propagate, and the cracks all originate from the subsurface of contact zone. Due to the different influence levels of the contact stress and bending fatigue stress, the initiation and propagation of the bending fretting fatigue cracks can be divided into three stages. Firstly, the cracks initiate from subsurface under the control of contact stress; then propagate to a larger angle direction under the joint control of contact stress and bending fatigue stress; lastly the cracks propagate vertically to contact surface until fracture failure under the control of bending fatigue stress.

The phase transformations and precipitation behavior were investigated by using Thermo-Calc software in the Fe-(18-21)Cr-(3-5)Al-(0-0.03)C-(0-0.2)Si-(0-0.2)Mn multicomponent system relevant to FeCrAl stainless steel during solidification. The vertical sections of this system were calculated by using the TCFE7 database. Based on these vertical sections, the influence of different elements was analyzed in the phase transformations during solidification and a diagram of the phase-transformation path of FeCrAl stainless steel was obtained during equilibrium solidification. The results indicate that the full-phase transformation path of FeCrAl stainless steel during the cooling process from 1600℃ to 300℃ is as follows:L→AlN+αδFe→AlN+αδFe+Cr7C3→AlN+αδFe+Cr7C3+Cr23C6→AlN+αδFe+Cr23C6→AlN+αδFe+Cr23C6+σ→AlN+αδFe+Cr23C6+σ+α'→AlN+αδFe+Cr23C6+α'. The precipitation of Cr7C3 and σ, during the solidification process mainly depends on the carbon and silicon contents in the system, respectively. Increasing the aluminum content can enlarge the stable region of αδFe+Cr7C3, lower the precipitation temperature of α', and restrain σ precipitation. Increasing the chromium content can reduce the stable region of αδFe+Cr7C3 and enlarge the stable region of σ and α'.

The influence of Ti (mass fraction 0.10%) and the joint additions of Ti (mass fraction 0.11%) and V (mass fraction 0.20%) on the hot ductility of as-cast high manganese austenitic steels were studied using a Gleeble-3500 thermo-mechanical simulator over a temperature range of 700 to 1200℃. Fracture surfaces and particles precipitated at different testing temperatures were investigated via scanning electron microscopy (SEM) and X-ray energy dispersive spectrometry (EDS). The hot ductility curves as a function of temperature of high-Mn austenitic steels showed that Ti addition leads to loss of ductility in almost the entire testing temperature range. Moreover, the joint additions of Ti and V do not exhibit any improvement in the hot ductility, resulting in relatively poor hot ductility behavior. The phase diagrams of precipitates in Ti-and Ti-V-bearing high-Mn austenitic steels in the temperature range of 700 to 1600℃ were calculated via Thermo-Calc commercial software. The calculation results show that Ti(C,N) in Ti-bearing highMn steel precipitates at 1499℃, which is much higher than its liquidus temperature. This illustrates that Ti(C,N) particles form in the liquid steel. SEM-EDS results show that Ti(C,N) and (Ti,V) C particles form along the austenitic grain boundaries and the triple junction. These particles retard the occurrence of dynamic recrystallization and accelerate the extension of cracks near the grain boundaries.

The solid-state desilication kinetics of silicon manganese powder and Brazil manganese powder was investigated by microwave heating and conventional heating. During the two processes, Brazil manganese powder which reacted with silicon in silicon manganese was used as the desilication agent. The mixture was heated up to different temperatures and preserved heat for some time by microwave heating and conventional heating, respectively. The silicon content of desilication materials was measured and the apparent activation energy of desilication reaction was calculated. The results show that the single raw material and the mixture could be heated up in the microwave field in a short time. The desilication rate increases with the increase of heating temperature and holding time by both heating methods. The desilication rate and the reaction rate under the microwave field are significantly higher than those by conventional heating. Microwave heating can increase the rate of solid phase desilication. The restrictive step of solid-state desilication kinetics of silicon manganese powder and Brazil manganese powders by microwave heating is the diffusion step. The apparent activation energy of desilication reaction under the microwave field is 102.93 kJ·mol-1, but the apparent activation energy of desilication reaction by conventional heating is 180 kJ·mol-1. The microwave heating field can improve the kinetics condition of solid phase desilication, increase the reaction rate of solid phase desilication and reduce the activation energy of desilication reaction.

The cleanliness evolution of SWRH82B steel produced by the BOFLFCC process was studied by systematic sampling and lab comprehensive analysis. The results show that the content of oxygen and the number of micro-inclusions significantly decrease after calcium treatment,while the content of nitrogen in molten steel slightly increases. Both the contents of oxygen and nitrogen sharply increase during the casting process. 97% of the micro-inclusions in casting billets are smaller than 5 μm. They mainly include trenchant angularity single Al2O3 inclusions,spherical complex inclusions of oxides with Ca S and Mn S,and complex inclusions of simple oxides or nitrides with Mn S. Calcium treatment after LF refining removes oxygen from molten steel efficiently,but increase the amount of Al2O3 inclusions in casting billets,which is harmful to the quality of SWRH82B steel. Due to serious lag entrapment,refractory erosion and reoxidation caused by unreasonable tundish structure,the cleanliness of liquid steel decreases.

Accurate predictions of monthly streamflow are of great importance for reservoir operation management. The existing approaches for the monthly streamflow predictions can be broadly classified into data-driven and process-based models. Predictive performance of data-driven models is highly sensitive to model structures and input variables. However, most studies focus on comparing model structures, which ignore the relationship between model inputs and monthly streamflows. Despite the growing interest in using sea surface temperature (SST) anomalies over specific areas as predictors in data-driven models for predicting monthly streamflows, spatial distribution patterns and correlation of sea surface temperature have rarely been considered in previous studies. Therefore, this study investigates the role of SST dipole on monthly streamflow prediction and the influence of different combinations of historical streamflow observations, atmospheric indices and SST dipoles on predictive performance. Different multiple linear regression (MLR) models are developed for the twelve months of the year to predict monthly inflows for the Tianyi Reservoir at lead times of 1 to 12 months. Results show that although historical streamflow observations have little value by themselves, they generally improve the predictive performance when used in combination with historical atmospheric indices or with SST dipoles for 1- to 3-month-ahead streamflow predictions. MLR models generally perform better when SST dipoles are included as predictors for monthly streamflow prediction at longer lead times. The largest improvements are found for September and November. For example, compared with using historical streamflow observations and atmospheric indices as predictors, streamflow observations and SST dipoles used as predictors have improved the averaged prediction accuracy by 7.1% and 9.3% for the two months with lead times of 1 to 12 months, respectively. [ABSTRACT FROM AUTHOR]

The technical feasibility of desulfurization, denitration and dioxin removal from sintering flue gas processed by blast furnace was discussed in theory. The reduction thermodynamics of sulfur dioxide and nitrogen oxides as well as the conditions for dioxin decomposition in a blast furnace were analyzed. The effects of blast with sintering flue gas instead of air on the theoretical flame temperature (TFT), blast volume, gas in hearth, top gas and sulfur content of hot metal were investigated. The results show that sulfur dioxide and nitrogen oxides can be reduced in the BF interior, and the lowest equilibrium volume fractions of sulfur dioxide, nitric oxide and nitrogen dioxide are 1.84×10-13%, 3.08×10-11% and 3.72×10-21%, respectively. Favorable thermodynamic conditions for dioxin decomposition are found in the blast furnace. Sulfur dioxide and carbon monoxide in sintering flue gas have little effect on the TFT, while nitrogen oxides can slightly increase the TFT. The TFT decreases by about 40.5% with a 1% increase in carbon dioxide volume fraction of sintering flue gas, but the thermal state of a hearth can be improved to the normal level by reducing the humidity and increasing the oxygen enrichment of blast. The blast volume, gas in hearth and top gas decrease with increasing carbon dioxide content of sintering flue gas. As the carbon dioxide content of sintering flue gas rises, the carbon monoxide and hydrogen contents of gas in hearth and the carbon monoxide, hydrogen, carbon dioxide and water contents of top gas increase, but the nitrogen contents of gas in hearth and top gas decrease. The sulfur quality content of hot metal is proportional to the sulfur dioxide content of flue gas and it is raised to 0.025% when the sulfur dioxide content increases to 2000 mg·m-3. The BF production can proceed smoothly with sintering flue gas blast instead of air through comprehensive operating measures, achieving the purpose of desulfurization, denitration and dioxin removal.

Microsegregation in low carbon Fe-25Mn-3Si-3Al TWIP steel produced in the laboratory and steel plant were systematically investigated by electron microprobe analysis. The results show that the dendritic segregation is serious in both the laboratorial ingot and mold casting after AOD steelmaking at the industrial plant. Additionally,microsegregation in the AOD ingot is higher,and the greatest amounts of segregation of Mn and Al are measured to be 6.8% and 2.4%,respectively. After electroslag remelting in the steel plant,the grain boundary segregation is serious,and it completely improves after a forging process. A higher alloy composition and a wider crystallization temperature interval are the main reasons for the serious microsegregation. All specimens of the TWIP steel have the same law. Mn shows obvious negative segregation,Al and Si exhibit positive segregation,and Al has the highest degree of segregation. The elements' solute distribution coefficient K of the TWIP steel was calculated using the Thermo-Calc software. It is found that the microsegregation laws of Mn and Al in theory are opposite to those in the experiment,and the main reason is silicon content.

A water/carbon dioxide system was used to study bubble growth dynamics in a molten steel/(N2,H2) supersaturation system. Bubble nucleation and growth mechanism models in the aqueous solution and the molten steel were respectively established.Bubble growth dynamics in the water/carbon dioxide system and the molten steel/(N2,H2) system was studied based on three different kinds of bubble growth mathematical models. Water modeling experimental data were used to validate the mathematical models. The influences of preprocessing pressure,post-processing pressure and the depth of molten steel on bubble growth were analyzed in the molten steel/(N2,H2) system. It is found that when using the technology of inclusion removal by bubble flotation,preprocessing pressure has significant effect on the bubble growth. However,post-processing pressure blocks the bubble growth,and with increasing post-processing pressure,the influence gradually strengthens. The depth of molten steel has retarding effect on the bubble growth,and with the increasing of the depth of molten steel,the influence gradually weakens. Compared with nitrogen bubbles,hydrogen bubbles in molten steel grow faster.