Numerical Analysis of the Influence of the Impinging Distance on the Scouring Efficiency of Submerged Jets

Water jet technology is widely used in submerged buried pipes as a non-traditional trenching process,often invol-ving a complex sediment response.An important adjustable and influential engineering variable in this technol-ogy is represented by the impinging distance.In this study,the FLOW-3D software was used to simulate the jet scouring of sand beds in a submerged environment.In particular,four sets of experimental conditions were con-sidered to discern the relationship between the maximum scour depth and mass and the impinging distance.As shown by the results,a critical impinging distance h0 exists by which the static scour depth can be maximized;the scour mass ratio between dynamic and static conditions decreases as the impinging distance increases.Moreover,the profile contours are similar when the erosion parameter Ec is in the range 0.35<Ec<2.Empirical equations applicable for predicting the jet trenching contour under both dynamic and static scour modes are also provided in this study.

Experimental and Three-Dimensional Numerical Simulation of Phenomena Induced by Submerged Oblique Jet Scouring

Scouring experiments were conducted using a three-dimensional laser scanning technology for angles of the jet spanning the interval from 0°to 30°,and the characteristics of the scour hole in equilibrium conditions were investigated accordingly.The results indicate that the optimal scouring effects occur when the jet angle is in the ranges between 15°and 20°.Moreover,the dimensionless profiles of the scour hole exhibit a high degree of similarity at different jet angles.Numerical simulations conducted using the Flow-3D software to investigate the bed shear stress along the jet impingement surface have shown that this stress is influenced by both the resultant force and the jet impingement surface area.It reaches its maximum value when the jet is vertical,decreases rapidly as the jet starts to tilt,then increases slightly,and decreases again significantly when the angle exceeds 20°.

交互思维理念下高校包装设计课程教学路径探索

随着社会经济的不断发展和科技的进步,包装设计作为一门重要的艺术和设计专业,对于满足人们日益增长的消费需求和提升产品附加值起着至关重要的作用。而交互思维理念强调学生与教师、学生与学生之间的互动和合作,注重学生的主体性和创造性。将其应用在高校包装设计课程教学中,有助于培养学生的创新意识和设计能力,提高其实践能力和团队合作能力。因而研究交互思维理念下高校包装设计课程教学路径有重要意义。对此,通过阐述交互思维理念在高校包装设计课程教学中的体现,进而分析交互思维理念下高校包装设计课程教学的路径,以期提升学生的设计水平。

A Nitride-Reinforced NbMoTaWHfN Refractory High-Entropy Alloy with Potential Ultra-High-Temperature Engineering Applications

Refractory high-entropy alloys(RHEAs)have promising applications as the new generation of hightemperature alloys in hypersonic vehicles,aero-engines,gas turbines,and nuclear power plants.This study focuses on the microstructures and mechanical properties of the NbMoTaW(HfN)_(x)(x=0,0.3,0.7,and 1.0)RHEAs.The alloys consist of multiple phases of body-centered cubic(BCC),hafnium nitride(HfN),or multicomponent nitride(MN)phases.As the x contents increase,the grain size becomes smaller,and the strength gradually increases.The compressive yield strengths of the NbMoTaWHfN RHEA at ambient temperature,1000,1400,and 1800℃ were found to be 1682,1192,792,and 288 MPa,respectively.The high-temperature strength of this alloy is an inspiring result that exceeds the high temperature and strength of most known alloys,including high-entropy alloys,refractory metals,and superalloys.The HfN phase has a significant effect on strengthening due to its high structural stability and sluggish grain coarsening,even at ultra-high temperatures.Its superior properties endow the NbMoTaWHfN RHEA with potential for a wide range of engineering applications at ultra-high temperatures.This work offers a strategy for the design of high-temperature alloys and proposes an ultra-high-temperature alloy with potential for future engineering applications.

Simulation of Seabed Erosion Produced by an Inclined Jet

Water jets are widely used in seabed scouring and desilting applications.In the present work,dedicated tests have been conducted using a jet scour model test platform and sand beds containing grains with different sizes.The FLOW-3D simulation software has also been used to tackle the problem form a numerical point of view.The boundary conditions of the simulation have been optimized to reduce the gap between the numerical results and the outcomes of the experimental tests.Scour area calculation has been based on a RNG k-εTurbulence model.Moreover,the FAVOR(Fractional Area Volume Obstacle Representation)technology has been selected for grid division to make the simulation results more accurate.Jet scours with inclination angles of 10–20°have been simulated.It has been found that jet scouring is greatly affected by the environmental water flow,that is,water flow can weaken the scouring capacity of the jets.

松辽黑猪、雷香猪、杜长大白猪肉质性状及肌肉营养成分比较研究

为了比较松辽黑猪、雷香猪、杜长大白猪肉质性状及肌肉营养成分,选取松辽黑猪、雷香猪、杜长大白猪进行屠宰,对肉质性状、肌肉氨基酸及脂肪酸含量进行测定,结果表明:松辽黑猪剪切力、肌内脂肪含量显著高于杜长大白猪(P<0.05),熟肉率显著高于雷香猪(P<0.05),雷香猪剪切力、肌内脂肪含量极显著高于杜长大白猪(P<0.01);松辽黑猪和雷香猪肌肉中丙氨酸含量极显著高于杜长大白猪(P<0.01),甘氨酸含量松辽黑猪显著高于雷香猪(P<0.05),极显著高于杜长大白猪(P<0.01);雷香猪亚油酸含量显著低于杜长大白猪(P<0.05)。文章对优质高端黑猪肉生产群体的选择提供了参考。

Janus亲/疏复合材料的制备及研究进展

近年来,Janus亲/疏复合材料因其特殊的润湿结构受到广泛关注。随着人们对Janus亲/疏复合材料认识和研究的不断深入,相应的制备技术愈发成熟,其应用领域也在不断扩大。文中简单介绍了Janus亲/疏复合材料的定向运输机制;重点总结了Janus亲/疏复合材料的制备方法,其中包括静电纺丝法、材料复合法、相分离法、光化学改性法、化学沉积法等,并对各种方法的优缺点进行了对比分析,同时对Janus亲/疏复合材料应用研究进行了归纳总结。最后,对Janus亲/疏复合材料的制备技术及应用领域进行了展望。

白藜芦醇对松辽黑猪精液冷冻的影响

试验旨在评价白藜芦醇(resveratrol,Res)对松辽黑猪公猪精液冷冻的影响。试验分为5组,分别为对照组(不添加Res)和Res处理组(在冷冻基础液中分别加入25μM、50μM、100μM、200μM浓度的Res)。采用手握法采集松辽黑猪精液,用5种冷冻基础液稀释,在25℃平衡1 h,17℃平衡2 h,4℃平衡3 h后灌装于0.5 mL细管中,在液氮上方3 cm处熏蒸10 min,保存在液氮罐中30 d后进行检测。样本解冻后分别检测精子活力、谷胱甘肽过氧化物酶(GSH-Px)活性、质膜完整性、过氧化氢酶(CAT)活性、顶体完整性、线粒体活性、活性氧簇(ROS)水平、DNA完整性、超氧化物歧化酶(SOD)活性以及丙二醛(MDA)水平。结果显示:与对照组相比,冷冻基础液中添加50μM Res可以显著提高冻融后精子的活力、SOD活性、质膜完整性、CAT活性、线粒体活性、GSH-Px活性、顶体完整性(P<0.05);可以显著降低精子ROS水平和MDA水平(P<0.05);添加Res对DNA完整性未表现出具有显著影响(P>0.05)。结论:猪精液冷冻前添加Res可改善冻融后精子质量,添加量50μM效果最佳,但Res是否可以改善公猪冷冻精液的体外受精及人工授精能力,有待于进一步的研究。

MEKK1, MKK1/MKK2 and MPK4 function together in a mitogen-activated protein kinase cascade to regulate innate immunity in plants

Mitogen-activated protein kinase （MAPK） cascades play important roles in regulating plant innate immune responses. In a genetic screen to search for mutants with constitutive defense responses, we identified multiple alleles of mpk4 and mekkl that exhibit cell death and constitutive defense responses. Bimolecular fluorescence complemen- tation （BiFC） analysis showed that both MPK4 and MEKK1 interact with MKK1 and MKK2, two closely related MAPK kinases, mkkl and mkk2 single mutant plants do not have obvious mutant phenotypes. To test whether MKK1 and MKK2 function redundantly, mkkl mkk2 double mutants were generated. The mkkl mkk2 double mutant plants die at seedling stage and the seedling-lethality phenotype is temperature-dependent. Similar to the mpk4 and mekkl mutants, the mkkl mkk2 double mutant seedlings accumulate high levels of H202, display spontaneous cell death, constitutively express Pathogenesis Related （PR） genes and exhibit pathogen resistance. In addition, activation of MPK4 by fig22 is impaired in the mkkl mkk2 double mutants, suggesting that MKK1 and MKK2 function together with MPK4 and MEKK1 in a MAP kinase cascade to negatively regulate innate immune responses in plants.

An Adaptive Vision Navigation Algorithm in Agricultural IoT System for Smart Agricultural Robots

As the agricultural internet of things(IoT)technology has evolved,smart agricultural robots needs to have both flexibility and adaptability when moving in complex field environments.In this paper,we propose the concept of a vision-based navigation system for the agricultural IoT and a binocular vision navigation algorithm for smart agricultural robots,which can fuse the edge contour and the height information of rows of crop in images to extract the navigation parameters.First,the speeded-up robust feature(SURF)extracting and matching algorithm is used to obtain featuring point pairs from the green crop row images observed by the binocular parallel vision system.Then the confidence density image is constructed by integrating the enhanced elevation image and the corresponding binarized crop row image,where the edge contour and the height information of crop row are fused to extract the navigation parameters(θ,d)based on the model of a smart agricultural robot.Finally,the five navigation network instruction sets are designed based on the navigation angleθand the lateral distance d,which represent the basic movements for a certain type of smart agricultural robot working in a field.Simulated experimental results in the laboratory show that the algorithm proposed in this study is effective with small turning errors and low standard deviations,and can provide a valuable reference for the further practical application of binocular vision navigation systems in smart agricultural robots in the agricultural IoT system.

Acidolysis hydrocarbon characteristics and significance of sediment samples from the ODP drilling legs of gas hydrate

To study on the significance and basis of acidolysis index to China marine gas hydrate exploring, since 2006, 111 samples derived from Leg 164 and 204 of the Ocean Drilling Program （ODP） were analyzed in the experiment center of China Petroleum Exploration Research Institute to obtain data on acidolysis hydrocarbon index and methane carbon isotopes by the gas chromatography （GC） of PE AutoSystem XL and isotope mass spectrometer （IRMS） of Finnigan MAT25 I. Through these, we study the reliability of the acidolysis method and characterize the gas hydrate potential. The results show that the acidolysis hydrocarbon index has a stable correspondence with the Gas Hydrate Stability Zone （GHSZ） in the ODE and that there are clear abnormal signs in shallow samples that might reliably reflect the existence of authigenic carbonate caused by hydrocarbon migration from bottom hydrate. We therefore propose that the ability to characterize the acidolysis hydrocarbon is crucial to submarine gas hydrate exploration in China.

U(VI) adsorption behavior onto polypyrrole coated 3R-MoS2 nanosheets prepared with the molten salt electrolysis method

To improve the separation capacity of uranium in aqueous solutions, 3R-MoS2 nanosheets were prepared with molten salt electro- lysis and further modified with polypyrrole (PPy) to synthesize a hybrid nanoadsorbent (PPy/3R-MoS2). The preparation conditions of PPy/3R- MoS2 were investigated and the obtained nanosheets were characterized with scanning electron microscope (SEM), high resolution transmis- sion electron microscope (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectro- scopy (XPS). The results showed that PPy/3R-MoS2 exhibited enhanced adsorption capacity toward U(VI) compared to pure 3R-MoS2 and PPy;the maximum adsorption was 200.4 mg/g. The adsorption mechanism was elucidated with XPS and FTIR: (1) negatively charged PPy/3R-MoS2 nanosheets attracted by an electrostatic interaction;(2) exposed C, N, Mo, and S atoms complexed with U(VI) through co- ordination;(3) Mo in the complex partly reduced the adsorbed U(VI) to U(IV), which further regenerated the adsorption point and continu- ously adsorbed U(VI). The design of the PPy/3R-MoS2 composite with a high adsorption capacity and chemical stability provides a new direc- tion for the removal of radionuclide.

Experimental Study on the Effect of the Inclination Angle on the Scouring Efficiency of Submerged Water Jets

The effects of oblique submerged scouring jets on sand beds with various particle sizes have been studied experimentally.In particular,a total of 25 experiments have been carried out to explore the influences of the jet angle and application time on the considered submerged sand beds.Test results conducted with a specially-designed device have shown that the scouring efficiency attains a maximum when the inclination angle is in the range between 15°and 20°and then it decreases when the inclination angle becomes higher.

Scrolled Production of Large-Scale Continuous Graphene on Copper Foils

We report an efficient and economical way for mass production of large-scale graphene films with high quality and uniformity.By using the designed scrolled copper-graphite structure,a continuous graphene film with typical area of 200×39 cm^2 could be obtained in 15 min,and the production rate of the graphene film and space utilization rate of the CVD reactor can reach 520 cm 2⋅min−1 and 0.38 cm−1⋅min−1,respectively.Our method provides a guidance for the industrial production of graphene films,and may also accelerate its large-scale applications.

Enhanced electrochemical CO_(2)-to-C_(2+) conversion from synergistic interaction between terrace and step sites on monocrystalline highindex Cu facets

1. Introduction The increasing global demand for sustainable energy sources and emerging environmental issues have pushed the development of energy conversion and storage technologies to the forefront of chemical research [1,2]. In particular, electrochemical CO_(2) reduction(CO_(2) R) to value-added fuels and chemicals presents a feasible pathway for renewable energy storage and could help mitigate the ever-increasing CO_(2) emissions [3].

Prospective study of high geodetic resolution to future VGOS reference point determination

The fast slewing rate and wide band of the VLBI2010 Global Observing System(VGOS) telescopes are beneficial to procure more observations and to obtain VLBI reference points(RPs) of high precisions.Meanwhile, with the development of synchronous tracking of fixed targets on telescopes during the observing, the RPs also can be determined in near real time based on a frame defined by other techniques. These opportunities provide us a possibility to explore the high geodetic resolution of VGOS telescopes. We design a thermal variation in RP as true values, and schedule a synchronous session of VGOS and target point(TP) series observing. Then VGOS delays and TP series are simulated and solved via piecewise functions. The results show that the accuracy of vertical component of the RP could be determined at an accuracy of 0.5 ± 0.3 mm in an hour using TP series, whereas the vertical components of RP solved by using VGOS delay measurements have a greater uncertainty due to the random error in the simulated atmosphere and bad radio source sky coverage in a shorter time interval. Some details in the data processing and accuracy evaluation are also introduced.

Adsorption of U(Ⅳ) onto Amidoxime-functionalized Hydrothermal Carbon in the Presence of Ca-U(Ⅳ)-CO3 Complexes

The aim is collecting uranium from groundwater in which uranium mainly exists in negative species,the amidoxime-functionalized hydrothermal carbon(AO-HTC)was synthesized.From the results of N2 adsorption-desorption and SEM,AO-HTC is a small spherical surface;FT-IR and Elemental analysis showed that the amidoxime group was successfully grafted onto the surface of the material;Zeta-potential measurement showed that the amino nitrogen atom is protonated in the oxime group.The optimum pH value of AO-HTC for uranium adsorption is 6.0,and the adsorption equilibrium is reached within 80 min,which is in accordance with the pseudo-second order adsorption kinetic model.The adsorption of uranium by AO-HTC accords with the Langmuir isotherm adsorption model,and the single-layer saturated adsorption capacity is 254.13mg·g^-1.The thermodynamic parameters calculated by the adsorption isotherm indicate that AO-HTC adsorption of uranium is a spontaneous endothermic chemical process and Carbonate ion,calcium ion and humic acid concentration have great influence on uranium adsorption.The experiments results show that AO-HTC has the potential to elimination of U(Ⅳ)from groundwater.

The combined effect of bromadiolone and ivermectin (iBr) in controlling both rodents and their fleas

Rodent pests not only cause severe agricultural loss but also spread zoonotic pathogens to human beings.Antico-agulant rodenticides are widely used to decrease the population densities of rodents but often lead to the spillover of ectoparasites becausefleas and ticks may gather on surviving rodents.Therefore,it is necessary to killfleas and ticks before culling rodents to minimize the risk of pathogen transmission.In this study,we used a mixture of ivermectin(an antiparasitic drug)and bromadiolone(an anticoagulant rodenticide)to control both rodent andflea/tick abundances.We found that in a laboratory test,0.01%ivermectin bait was not lethal for greater long-tailed hamsters after 7 days of treatment,while 0.1%ivermectin bait was lethal for approximately 33%of treated rodents.In afield test,bait containing 0.001%,0.005%,0.01%,and 0.05%ivermectin decreased the number offleas per vole of Brandt’s voles to 0.42,0.22,0.12,and 0.2,respectively,compared with 0.77 in the control group,indicating that 0.01%ivermectin bait performed best in removingfleas.In another laboratory test,bait containing a 0.01%ivermectin and 0.005%bromadiolone mixture caused the death of all voles within 6–14 days after the intake of the bait.In thefield test,the bait containing 0.01%ivermectin and 0.005%bromadiolone reduced the average number offleas per vole to 0.35,which was significantly lower than the 0.77 of the control group.Our results indicate that a 0.01%ivermectin and 0.005%bromadiolone mixture could be used to control both rodents andfleas to minimize the spillover risk of disease transmission when using traditional rodenticides.

Antifertility effects of EP-1 (quinestrol and levonorgestrel) on Pacific rats (Rattus exulans)

Pest rodents pose a serious threat to island biodiversity.Fertility control could be an alternative approach to control the impact of rodents on these islands.In this study,we examined the antifertility effects of EP-1 baits containing quinestrol(E)and levonorgestrel(P)using a dose of 50 ppm E and P at three different ratios(E:P ratio=1:2,1:1,and 2:1)on Pacific rats(Rattus exulans)in the Xisha Islands,Hainan,China.Compared to the control group,all animals in EP-1 treatment groups showed significantly decreased food intake and body weight.In treated males,there were obvious abnormalities in testis structure and a significant decrease of relative seminal vesicle weight,but no significant effect on relative uterine and ovarian weights(g kg-1 body weight),or ovarian structure in females.Adding 8%sucrose to the original 50-ppm baits(E:P ratio=1:1)significantly increased bait palatability for males and females.This dose induced uterine edema and abnormalities of ovarian structure in females but had no significant negative effect on the relative testis,epididymis,and seminal vesicle weights(g kg-1 body weight)or sperm density in males.In summary,50-ppm EP-1(1:1)baits have the potential to disrupt the fertility of females,and 8%sucrose addition to the EP-1 baits(E:P ratio=1:1)could improve bait palatability.This dose disrupted the testis structure in males.Future studies are needed to improve bait acceptance and assess the antifertility effects of EP-1(1:1)on Pacific rats in captive breeding trials and underfield conditions.

Single-crystallization of electrolytic copper foils

Depending on the production process,copper(Cu)foils can be classified into two types,i.e.,rolled copper(r-Cu)foils and electrolytic copper(e-Cu)foils.Owing to their high electrical conductivity and ductility at low cost,e-Cu foils are employed extensively in modern industries and account for more than 98%of the Cu foil market share.However,industrial e-Cu foils have never been single-crystallized due to their high density of grain boundaries,various grain orientations and vast impurities originating from the electrochemical deposition process.Here,we report a methodology of transforming industrial e-Cu foils into single crystals by facet copy from a single-crystal template.Different facets of both low and high indices are successfully produced,and the thickness of the single crystal can reach 500μm.Crystallographic characterizations directly recognized the single-crystal copy process,confirming the complete assimilation impact from the template.The obtained single-crystal e-Cu foils exhibit remarkably improved ductility(elongation-to-fracture of 105%vs.25%),fatigue performance(the average numbers of cycles to failure of 1600 vs.200)and electrical property(electrical conductivity of 102.6%of the international annealed copper standard(IACS)vs.98.5%)than original ones.This work opens up a new avenue for the preparation of single-crystal e-Cu foils and may expand their applications in high-speed,flexible,and wearable devices.