Formation and control of the surface defect in hypo-peritectic steel during continuous casting:A review

Hypo-peritectic steels are widely used in various industrial fields because of their high strength,high toughness,high processability,high weldability,and low material cost.However,surface defects are liable to occur during continuous casting,which includes depression,longitudinal cracks,deep oscillation marks,and severe level fluctuation with slag entrapment.The high-efficiency production of hypo-peritectic steels by continuous casting is still a great challenge due to the limited understanding of the mechanism of peritectic solidification.This work reviews the definition and classification of hypo-peritectic steels and introduces the formation tendency of common surface defects related to peritectic solidification.New achievements in the mechanism of peritectic reaction and transformation have been listed.Finally,countermeasures to avoiding surface defects of hypo-peritectic steels duiring continuous casting are summarized.Enlightening certain points in the continuous casting of hypo-peritectic steels and the development of new techniques to overcome the present problems will be a great aid to researchers.

保水剂特性测定及其在农业中的应用

高分子化学材料的保水剂 ,具有高倍吸水和保水能力 ,种类较多。该研究测定了钠类保水剂主要化学特性改土保土效应。通过田间试验 ,分析其对作物产量和肥料利用率的影响。研究表明 ,保水剂溶液钠离子和电导度随其浓度增加而增加 ,但增幅较小 ,对 p H值影响不大。钙、镁等二价离子对聚丙稀酸钠保水剂的吸水力拮抗作用明显 ,与尿素混用无不良效果。土壤加入保水剂后 ,其保水能力增加 ,改善结构 ,沙壤土较重壤土更显著。当土壤中保水剂含量在 0 .0 0 5 %～ 0 .0 1%范围时 ,土壤团聚体增加量明显。在 - 0 .5 MPa土壤水势压内 ,含保水剂 0 .5 %的土壤中 90 %水分可为植物根系利用。研究认为 ,保水剂保水作用主要表现 4方面 :自身保水、改良土壤结构增加土壤保水、促进植物生长提高肥料利用率、缓慢释水减少蒸发。田间试验发现 ,穴施 15 kg/hm2的保水剂的玉米和马铃薯分别增产 2 2 %和 16 % ,投产比为 1∶ 3.5和 1∶ 4 .2。保水剂与尿素或尿素磷肥混合使用于玉米 ,可分别提高尿素和磷肥利用效率 18.72 %和 2 7.0 6 %。

Cobalt-nanoparticle catalysts derived from zeolitic imidazolate framework@MXene composites for efficient oxidative self-coupling of benzylamines

In this study,we synthesize a catalyst comprising cobalt nanoparticles supported on MXene by pyrolyzing a composite in a N2 environment.Specifically,the composite comprises a bimetallic Zn/Co zeolitic imidazole framework grown in situ on the outer surface of MXene.The catalytic efficiency of the catalyst is tested for the self-coupling of 4-methoxybenzylamine to produce value-added imine,where atmospheric oxygen(1 atm)is used as the oxidant.Based on the results,the catalyst displayed impressive catalytic activity,achieving 95.4%yield of the desired imine at 383 K for 8 h.Furthermore,the catalyst showed recyclability and tolerance toward benzylamine substrates with various functional groups.The outstanding performance of the catalyst is primarily attributed to the synergetic catalytic effect between the cobalt nanoparticles and MXene support,while also benefiting from the three-dimensional porous structure.Additionally,a preliminary investigation of potential reaction mechanisms is conducted.

Delivering food safety

A delegation from the Australian Academy of Technological Sciences and Engineering traveled to Beijing in April 2016 to jointly run a workshop on technology advances in food safety with the Chinese Academy of Engineering. This brief summary from the Australian delegation identifies the pyramid of interlocking issues which must be addressed to deliver food safety. Systems and technology provide the necessary base, on which culture and then trust can be built to facilitate the delivery of food safety now and in the future.

Soil-Food-Environment-Health Nexus for Sustainable Development

Changes in soil properties and processes can influence food and environmental quality,thus,affecting human health and welfare through biogeochemical cascades among soil,food,environment,and human health.However,because many soil properties change much more slowly than do management practices and pollution to soil,the legacy of past influences on soil can have long-term effects on both human health and sustainability.It is essential and urgent to manage soils for health and sustainability through building the soil-food-environment-health nexus.

The Warming Climate Aggravates Atmospheric NitrogenPollution in Australia

Australia is a warm country with well-developed agriculture and a highly urbanized population.How these specific features impact the nitrogen cycle,emissions,and consequently affect environmental and human health is not well understood.Here,we find that the ratio of reactive nitrogen(Nr)losses to air over losses to water in Australia is 1.6 as compared to values less than 1.1 in the USA,the European Union,and China.Australian Nr emissions to air increased by more than 70%between 1961 and 2013,from 1.2 Tg N yr^(-1) to 2.1 Tg N yr^(-1).Previous emissions were substantially underestimated mainly due to neglecting the warming climate.The estimated health cost from atmospheric Nr emissions in Australia is 4.6 billion US dollars per year.Emissions of Nr to the environment are closely correlated with economic growth,and reduction of Nr losses to air is a priority for sustainable development in Australia.

Healthy soils for sustainable food production and environmental quality

Soil is the foundation for sustainable foodproduction and environmental protection. Created byunsustainable land management practices and a range ofsocial, economic and environmental drivers, soil degrada-tion and pollution have been an ongoing threat tointernational food security and environmental quality.Soil degradation and pollution assessments are, however,often focused on the soil itself with little scope to devisenew soil management approaches that match foodproduction systems and/or environmentalprotection.This study draws lessons from an Australia-China JointResearch Center Program, Healthy Soils for SustainableFood Production and Environmental Quality: a researchplatform that has brought together multi-disciplinaryapproaches fromworld-renowned universitiesandresearch organizations in Australia and China. To thisend, a framework is presented for future soil managementin a new way that combines excellence in research,industry and policymakers in a partnership that will ensurenot only the right focus of the research but also that high-quality outputs will be transferable to industry and end-users.

Effect of lignite amendment on carbon and nitrogen mineralization from raw and composted manure during incubation with soil

The application of animal manure as a source of plant nutrients requires the determination of the amount and pattern of nutrient mineralization from manure.A laboratory incubation study was conducted to investigate the influence of lignite amendment and lignite type on carbon(C)and nitrogen(N)mineralization in raw(feedstock)and composted cattle manure following application to soil at 30 and 60 t ha^(-1).The mineralization of C and N was determined by measuring changes in CO_(2) evolution and mineral N(NH_(4)^(+)-N+NO_(3)^(-)-N)over 40 d.The results showed that lignite amendment suppressed the amount of manure C mineralized in both feedstock and compost,with the effect being more pronounced in the compost.Over the 40-d incubation,the percentage of applied C mineralized was 26.4%-27.8%and 16.3%-21.4%in unamended and lignite-amended feedstocks,respectively.The corresponding C mineralized in the composts was 12.4%-14.1%and 3.5%-6.5%.Lignite had no significant effect on the net N mineralized in compost(4.8%-6.7%and2.5%-7.8%in unamended and lignite-amended composts,respectively).Lignite had either no effect or increased the net N mineralized in feedstock(from3.2%-8.7%without lignite to 10.4%-13.5%)depending on the type of lignite used.This study suggests that using lignite-amended manure,especially when composted,has the potential to build up soil organic C without limiting the availability of mineral N.

High-Temperature Plasticity Enhanced by Multiple Secondary Phases in a High-Si Austenitic Stainless Steel

An austenitic stainless steel with 6 wt% Si and multiple secondary phases was produced with the aim to achieve enhanced plasticity during hot deformation.The micro structure of the steel after fracture was characterized via electron back-scattered diffraction,transmission Kikuchi diffraction and scanning transmission electron microscopy.From the tail of the gage to the necking region,the microstructure of the material evolved from low-angle grain boundaries(LAGB s) to mixtures of LAGBs and high-angle grain boundaries(HAGBs),and fine equiaxed recrystallized grains.The elongation to failure in the tensile test exceeds 167%.During the hot deformation,continuous dynamic recrystallization of the austenitic matrix was promoted by the multiple secondary phases.The dislocations introduced by the secondary phases were rearranged and continuously transformed into HAGBs.The initially coarse grains(30.5 μm) were refined into ultra-fine equiaxed grains(1 μm),which contributed significantly the enhanced plasticity during hot deformation of the steel.In the necking area of the sample,twins were nucleated in the stress concentration regions and accommodated the local strain by discontinuous dynamic recrystallization,which was also beneficial to improving the plasticity.

A Credit System to Solve Agricultural Nitrogen Pollution

Increasing amounts of nitrogen fertilizer have been used in agriculture during the last decades to boost food production for the increasing global human population.The marked increase in reactive nitrogen use has also contributed to severe nitrogen pollution and multiple impacts on human and ecosystems'health.1 Nitrogen is an important precursor to air pollution(e.g.,fine particulate matter,near-surface ozone),water pollution(algal blooms,nitrate contamination),biodiversity loss(nitrogen deposition and eutrophication),soil acidification(ammonium fertilizer use),and global warming(nitrous oxide).2 Agricultural nitrogen pollution has decreased in some high-income countries,such as those in the European Union(EU),during the last decades,but the remaining nitrogen pollution still causes serious damage.The societal cost of nitrogen pollution by agriculture in the EU has been estimated to range from V35 to V230 billion per year and this cost appears to be greater than the farm profits from nitrogen fertilizer use,which range from V20 to V80 billion per year.3 Socioeconomic trade-offs between farmers and society need to be introduced to decrease nitrogen pollution.

Effects of organic amendments on soil properties and growth characteristics of Melon(Cucumis melo L.)under saline irrigation

Establishing strategies of organic amendments application to mitigate the adverse effects of saline irrigation are essential for the sustainable agriculture.A two-year pot experiment was conducted using combinations of organic amendments including effective microorganisms(EM),biochar(BC)and digestate(Di)to investigate their effects on soil and melon(Cucumis melo L.)compared with the recommended NPK fertilizer and Control(CK)under two levels of irrigation water salinity(SL0:0.25 dS/m,SL1:2.0 dS/m).Results showed combined applications of organic amendments could significantly(p<0.05)increase soil pH and organic matter(OM)compared to NPK and CK.Application of organic amendments containing BC evidently increased the sodium adsorptive capacity(SAC)under saline water solution.The combined application of EM,BC and Di(EM+BC+Di)could significantly(p<0.05)improve soil available water retention under SL0 and SL1 compared with other treatments.Results also showed organic amendments application can significantly(p<0.05)enhance the photosynthetic rate(Pr)and reduce sodium ion(Na+)content in melon leaves.EM+BC+Di could significantly(p<0.05)increase water use efficiency(WUE)and fruit yield of melon under SL0 and SL1 in comparison to other treatments.It proved that EM+BC+Di had a positive effect on soil improvement,melon growth,WUE and fruit yield.Moreover,EM+BC+Di could be used as an alternative strategy for mineral NPK fertilization of melon at reasonable dosages and frequencies under saline irrigation.

SUSTAINABLE NITROGEN MANAGEMENT IN AUSTRALIAN AGROECOSYSTEMS: CHALLENGES AND OPPORTUNITIES

Nitrogen is an essential nutrient that supports life,but excess N in the humanenvironment system causes multiple adverse effects from the local to the global scale.Sustainable N management in agroecosystems,therefore,has become more and more critical to address the increasing concern over food security,environmental quality and climate change.Australia is facing a serious challenge for sustainable N management due to its emission-intensive lifestyle(high level of animal-source foods and fossil fuels consumption)and its diversity of agricultural production systems,from extensive rainfed grain systems with mining of soil N to intensive crop and animal production systems with excessive use of N.This paper reviews the major challenges and future opportunities for making Australian agrifood systems more sustainable,less polluting and more profitable.

Human-caused increases in reactive nitrogen burial in sediment of global lakes

Human activities have increased reactive nitrogen(Nr)input to terrestrial ecosystems compared with the pre-industrial era.However,the fate of such Nr input remains uncertain,leading to missing sink of the global nitrogen budget.By synthesizing records of Nr burial in sediments from 303 lakes worldwide,here we show that 9.6±1.1 Tg N year^(-1)(Tg=10^(12) g)accumulated in inland water sediments from 2000 to 2010,accounting for 3%-5% of global Nr input to the land from combined natural and anthropogenic pathways.The recent Nr burial flux doubles pre-industrial estimates,and Nr burial rate significantly increases with global increases in human population and air temperature.Sediment ratios of C:N decrease after 1950 while N:P ratios increase over time due to increasingly elevated Nr burial and other related processes in lakes.These findings imply that Nr burial in lakes is overlooked as an important global sink of Nr input to terrestrial ecosystems.