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| 1 | Response of the northwestern Pacific upper water δ^(13)C to the last deglacial ventilation of the deep Southern Ocean显示文摘The deglacial δ~13C minimum events that originated from the ventilation of the deep Southern Ocean around Antarctica, have been recorded in a range of marine sediments from the southern to tropical oceans in late Pleistocene. However, the broad δ~13C minimum event was also reported as far as to the northern middle latitudes, in northwestern Pacific marginal sea areas, during the last deglaciation. In the northwestern Pacific, forcing from the northern high latitudes is strongly expressed, while the records of in- fluence from the southern high latitudes are few. The Kuroshio Source Region (KSR) forms a boundary between the northwestern Pacific and the southern, tropical Pacific. So, high-resolution planktonic foraminiferal records in core MD06-3054 from the KSR are well positioned to identify signals from the southern hemisphere in the northwestern Pacific. Planktonic foraminiferal tests from the upper 1030 cm of the core were subject to AMS14C, carbon and oxygen isotopic measurements. A negative excursion was found to occur from about 20.0-6.0 ka BP in δ~13C records of both surface (Globigerinoides ruber) and subsurface (Pulleni- atina obliquiloculata) dwellers, but the overall trends of the two curves have reversed since 26.5 ka BP. Moreover, the δ~13C rec- ord of G. ruber (the surface dweller) shows a robust link to the record of atmospheric CO2, and its changes precede the records of P. obliquiloculata (the subsurface dweller). According to the hydrologic conditions, the broad δ~13C minimum event recorded in the KSR is also a response to the increasing ventilation of the deep Southern Ocean around Antarctica during the last deglaciation. The inconsistency between the records of the surface and subsurface dwellers was possibly caused by the ways that the low δ~13C signal was transmitted. Subsurface water primarily received the low δ~13C signal from the Antarctic Intermediate Water (AAIW), whereas the surface water was probably mainly impacted by atmospheric CO2 in the KSR. The records from the KSR confirm the deduction that the broad δ~13C minimum event in the Okinawa Trough was due to the impact of tropical Pacific surface water dur- ing the last deglaciation, and suggest that signals from the southern high latitudes also can be delivered to the northern middle latitudes. | CHEN ShuangXi LI TieGang TANG Zheng QIU XiaoHua XIONG ZhiFang NAN QingYun XU ZhaoKai CHANG FengMing | 2011 | Chinese Science Bulletin2011，56，24： | 5 |
| 2 | Sea-level changes controlled detrital sediment inputs to the Bicol Shelf in the western Philippine Sea since 150 ka显示文摘Detrital sediments derived from the Philippine Islands are one of the main sources of deep-sea sediments in the western Philippine Sea.However,systematic research on their characteristics and transport mechanisms are lacking.We used parametric end-member analysis to quantitatively partition the grain size of detrital sediments in core MD06-3052 from the Bicol Shelf in the western Philippine Sea;three endmembers EMI,EM2,and EM3,whose respective modes were at 2,10,and 45 μm,were separated.We also measured the Sr and Nd isotopic compositions of different size fractions(<4 and >20 μm) of the detrital sediments and the results showed that the detrital sediments mainly originate from the Philippine Islands.Components EMI and EM2 are transported to the Bicol Shelf mainly by surface and bottom currents from the islands,and component EM3 is delivered by gravity flow from the exposed shelf during low sea-level stands.The content of the total detrital fraction and the three end-members,as well as the mass accumulation rates(MARs) of the coarse detritus(EM2 and EM3),were considerably higher during glacial periods(40-14 ka and 150-130 ka) than during other intervals;the glacials corresponded to a low sea level,while the MAR of the fine detritus(EMI) did not increase remarkably during 40-14 ka.We therefore concluded that the input of coarse detritus to the Bicol Shelf from the islands was mainly controlled by sea-level change.Variations of the input of fine-grained detritus(EM1) was influenced not only by sea level but also by ocean currents and regional precipitation.Overall,our results help understand 'source-to-sink' processes in the western Pacific marginal seas and their response to global change. | ZHANG Zhishun JIANG Fuqing LI Tiegang YANG Dezhou ZHOU Xiaojing XIONG Zhifang QIU Xiaohua JIA Qi YAN Yu FENG Xuguang | 2020 | Journal of Oceanology and Limnology2020，38，4： | 2 |
| 3 | Paleoproductivity and paleoredox conditions during late Pleistocene accumulation of laminated diatom mats in the tropical West Pacific显示文摘 | Zhifang Xiong Tiegang Li Thomas Algeo Qingyun Nan Bin Zhai Bo Lu | 2012 | Chemical Geology2012，，： | 1 |
| 4 | Revisiting the dependence of thermocline-dwelling foraminiferal B/Ca on temperature and [CO32-], and its application in reconstruction of the subsurface carbonate system in the tropical western Pacific since 24 ka显示文摘The B/Ca ratio of planktonic foraminifer shells has been used as a proxy for reconstructing past ocean carbonate chemistry. However, recent studies have revealed significant uncertainties associated with this proxy, such as whether seawater temperature or [CO^2-3 ] is the dominant control on the partition coefficient (KD) of planktonic foraminiferal B/Ca. To address these uncertainties and thus improve our understanding of the planktonic foraminiferal B/Ca proxy, we analysed B/Ca ratios in the tests of Neogloboquadrina dutertrei (300- 355 μm) and Pulleniatina obliquiloculata (355- 400 μm) in surface sediment samples from the tropical western Pacific and South China Sea. The relationship between these B/Ca ratios and bottom water calcite saturation states (Δ[CO^2-3 ]) is weak, thus suggesting only a small dissolution effect on the B/Ca of the two species. The correlation coefficients (R2) between the B/Ca ratios of N. dutertrei and P. obliquiloculata and environmental parameters (e.g., temperature, salinity, phosphate, DIC and ALK) in the tropical western Pacific and South China Sea are not high enough to justify using B/Ca ratios as a palaeoenvironmental proxy in the study areas. The significant correlation between KD values of N. dutertrei and P. obliquiloculata and carbonate system parameters (e.g.,[CO^2-3 ], DIC, ALK, pH and [HCO^-3 ]) in the study area reflect chemical links between the KD denominator and these variables. Based on our surface sediment calibration, an empirical relationship between the KD of N. dutertrei and temperature is proposed in the tropical western Pacific. We also generated a record of B/Ca ratios in N. dutertrei (300 -355 μm) from Core MD06-3052 in the tropical western Pacific over the past 24 ka to evaluate the application of the revised B/Ca proxy method. Based on the reconstructed empirical relationship for B/Ca and subsurface seawater ALK, we estimated subsurface seawater carbonate system parameters in the tropical western Pacific since 24 ka. In general, the estimated subsurface seawater pH and [CO^2-3 ] show an increase with time, and the record of subsurface seawater pCO2 shows a decrease with time, in the tropical western Pacific over the past 24 ka. The consistent trends in subsurface seawater pCO2 and opal flux during deglaciation may imply that the reported increase in subsurface water pCO2 in the study area was promoted by enhanced upwelling in the Southern Ocean. | Jingteng Guo Tiegang Li Zhifang Xiong Xiaohua Qiu Fengming Chang | 2019 | Acta Oceanologica Sinica2019，38，9： | 1 |
| 5 | Evolution of microstructures and mechanical properties with tempering temperature of a pearlitic quenched and tempered steel显示文摘Instead of conventional quenching and tempering,fast austenitization from an initial microstructure of lamellar pearlite followed by quenching and tempering was carried out,leading to the formation of inhomogeneous microstructure.It comprised different morphologies of lath martensite and retained austenite(RA).The effect of tempering temperature on microstructure evolution and tensile properties was systematically investigated.With increasing tempering temperature from 150 to 250℃,transition carbides gradually coarsened and their amount increased,the dislocation density in martensitic laths gradually decreased,and RA fraction decreased from 10.9%to 2.2%.The precipitation and dislocation strengthening can ensure a high strength,while RA can ensure a good ductility,leading to a simultaneous increase in the strength and ductility when decreasing tempering temperature.Specifically,the best combination of tensile properties(ultimate tensile strength of 2133±41 MPa and total elongation of 11.1%±1.3%)was achieved after tempering at 150℃. | De-zhen Yang Zhi-ping Xiong Chao Zhang Guan-zheng Feng Zhifang Cheng Xing-wang Cheng | 2022 | Journal of Iron and Steel Research(International)2022，29，9： | 1 |
| 6 | VGWO: Variant Grey Wolf Optimizer with High Accuracy and Low Time Complexity显示文摘The grey wolf optimizer(GWO)is a swarm-based intelligence optimization algorithm by simulating the steps of searching,encircling,and attacking prey in the process of wolf hunting.Along with its advantages of simple principle and few parameters setting,GWO bears drawbacks such as low solution accuracy and slow convergence speed.A few recent advanced GWOs are proposed to try to overcome these disadvantages.However,they are either difficult to apply to large-scale problems due to high time complexity or easily lead to early convergence.To solve the abovementioned issues,a high-accuracy variable grey wolf optimizer(VGWO)with low time complexity is proposed in this study.VGWO first uses the symmetrical wolf strategy to generate an initial population of individuals to lay the foundation for the global seek of the algorithm,and then inspired by the simulated annealing algorithm and the differential evolution algorithm,a mutation operation for generating a new mutant individual is performed on three wolves which are randomly selected in the current wolf individuals while after each iteration.A vectorized Manhattan distance calculation method is specifically designed to evaluate the probability of selecting the mutant individual based on its status in the current wolf population for the purpose of dynamically balancing global search and fast convergence capability of VGWO.A series of experiments are conducted on 19 benchmark functions from CEC2014 and CEC2020 and three real-world engineering cases.For 19 benchmark functions,VGWO’s optimization results place first in 80%of comparisons to the state-of-art GWOs and the CEC2020 competition winner.A further evaluation based on the Friedman test,VGWO also outperforms all other algorithms statistically in terms of robustness with a better average ranking value. | Junqiang Jiang Zhifang Sun Xiong Jiang Shengjie Jin Yinli Jiang Bo Fan | 2023 | Computers, Materials & Continua2023，77，11： | 0 |
| 7 | Relating the composition of continental margin surface sediments from the Ross Sea to the Amundsen Sea,West Antarctica,to modern environmental conditions显示文摘Investigating the multiple proxies involving productivity,organic geochemistry,and trace element(TE)enrichment in surface sediments could be used as paleoenvironment archives to gain insights into past and future environmental conditions changes.We present redox-sensitive TEs(Mn,Ni,Cu,U,P,Mo,Co,V,Zn,and Cd),productivity-related proxies(total organic carbon and opal),and total nitrogen and CaCO_(3) contents of bulk surface sediments of this area.The productivity proxies from the shelf and coastal regions of the Ross and the Amundsen seas showed that higher productivity was affiliated with an area of nutrient-rich deep water upwelling.The upwelling of weakly corrosive deep water may be beneficial for preserving CaCO_(3),while highly corrosive dense water,if it forms on the shelf near the coastal region(coastal polynya),could limit the preservation of CaCO_(3) in modern conditions.There were no oxic or anoxic conditions in the study area,as indicated by the enrichment factors of redox-sensitive TEs(Mn,Co,and U).The enrichment factor of Cd,which is redox-sensitive,indicated suboxic redox conditions in sediment environments because of high primary productivity and organic matter preservation/decomposition.The enrichment factors of other redox-sensitive TEs(P,Ni,Cu,V,and Zn)and the correlations between the element/Ti ratio with productivity and nutrient proxies indicated that the organic matter decomposed,and there was massive burial of phytoplankton biomass.There was variation in the enrichment,such that sediments were enriched in P,Mo,and Zn,but depleted in Ni,Cu,and V. | WANG Jiakai LI Tiegang TANG Zheng XIONG Zhifang LIU Yanguang CHEN Zhihua CHANG Fengming | 2022 | Advances in Polar Science2022，33，1： | 0 |
| 8 | Calcification of planktonic foraminifer Neogloboquadrina pachyderma(sinistral) controlled by seawater temperature rather than ocean acidification in the Antarctic Zone of modern Sothern Ocean显示文摘Neogloboquadrina pachyderma(sinistral), the dominant planktonic foraminiferal species in the mid-to-high latitude oceans, represents a major component of local calcium carbonate(CaCO) production. However, the predominant factors,governing the calcification of this species and its potential response to the future marine environmental changes, are poorly understood. The present study utilized an improved cleaning method for the size-normalized weight(SNW) measurement to estimate the SNW of N. pachyderma(sin.) in surface sediments from the Amundsen Sea, the Ross Sea, and the Prydz Bay in the Antarctic Zone of the Southern Ocean. It was found that SNW of N. pachyderma(sin.) is not controlled by deep-water carbonate dissolution post-mortem, and can be therefore, used to reflect the degree of calcification. The comparison between N. pachyderma(sin.) SNW and environmental parameters(temperature, salinity, nutrient concentration, and carbonate system) in the calcification depth revealed that N. pachyderma(sin.) SNWs in the size ranges of 200–250, 250–300, and 300–355 μm are significantly and positively correlated with seawater temperature. Moreover, SNW would increase by ~30% per degree increase in temperature, thereby suggesting that the calcification of N. pachyderma(sin.) in the modern Antarctic Zone of the Southern Ocean is mainly controlled by temperature, rather than by other environmental parameters such as ocean acidification. Importantly, a potential increase in calcification of N. pachyderma(sin.) in the Antarctic Zone to produce CaCOwill release COinto the atmosphere. In turn, the future ocean warming will weaken the ocean carbon sink, thereby generating positive feedback for global warming. | Qianwei SONG Bingbin QIN Zheng TANG Yanguang LIU Zhihua CHEN Jingteng GUO Zhifang XIONG Tiegang LI | 2022 | Science China Earth Sciences2022，65，9： | 0 |
| 9 | Morphotype dependence of Globigerinoides ruber(white)and Trilobatus sacculifer Mg/Ca ratios in the western tropical Pacific:implications for reconstructing the mixed-layer depth显示文摘Planktonic foraminifer Globigerinoides ruber(white)and Trilobatus sacculifer are the most frequently used mixedlayer dwelling species for reconstructing past oceanic environments.Specifically,the Mg/Ca ratios of these two foraminiferal species have been used for reconstructing tropical/subtropical changes in sea surface temperature(SST).However,these two species have different morphotypes,of which the spatial and temporal differences in Mg/Ca ratios and their influencing factors are still unclear.Our objective is to investigate the potential differences between the Mg/Ca ratios of these different morphotypes of G.ruber(white)and T.sacculifer in the western Philippine Sea(WPS)and determine their implications for the reconstruction of SST and upper-ocean structure.Mg/Ca measurements are made on two basic morphotypes of G.ruber(white)[sensu stricto(s.s.)and sensu lato(s.l.)]and T.sacculifer[with(w)and without(w/o)a sac-like final chamber]on samples of Site MD06-3047B from the WPS.Our results reveal that Mg/Ca ratios of different G.ruber morphotypes show consistent differences;and those of T.sacculifer morphotypes show staged variations since MIS 3.It is suggested to select a single morphotype for reconstructing SST changes using the Mg/Ca ratios of G.ruber and T.sacculifer in the WPS.Furthermore,the Mg/Ca ratios between G.ruber s.s.and G.ruber s.l.[Δ(Mg/Ca)_(G.ruber s.s.-s.l.)]downcore MD06-3047B covaries with indexes of summer monsoon.Combining with the core-top results,showing regional variation of differences in theΔ(Mg/Ca)_(G.ruber s.s.-s.l.)over the western tropical Pacific,we propose thatΔ(Mg/Ca)_(G.ruber s.s.-s.l.)may tend to reflect summer mixed layer depth. | Qi Jia Tiegang Li Zhifang Xiong Bingbin Qin | 2023 | Acta Oceanologica Sinica2023，42，11： | 0 |
| 10 | Mechanical Properties of a Eucalyptus-Based Oriented Oblique Strand Lumber for Structural Applications显示文摘Wood and wood-based composite materials have gained increasing attention in the sustainable building industry because of their renewability and environmental friendliness.Oriented oblique strand lumber(Eucalyptus Strand Wood,ESWood),which is manufactured from fast-growing small diameter eucalyptus wood(Eucalyptus urophylla×E.grandis),is introduced in this paper.Small clear specimen tests were conducted to determine the mechanical properties of ESWood material while full-scale component tests were performed to observe the structural performance of ESWood beams.A comparison of mechanical properties of ESWood with other wood/bamboo-based materials is then reported.From the results presented herein,it appears that the strength and stiffness properties of ESWood are affected by grain directionality and glued layers.However,it still has preferable mechanical properties as a building material,which is comparable or superior to those of other engineered wood/bamboo-based products(e.g.,Sitka spruce,LVL,OSL,Glulam,and Glubam).Furthermore,results from full-scale component tests show the stable mechanical performance of beams made by ESWood.This study makes a significant contribution to a potential utilization of fast-growing eucalyptus for general use in construction,and the presented mechanical tests results can serve as a fundamental data for more applications of ESWood in practical engineering. | Jiawei Chen Haibei Xiong Zhifang Wang Linqing Yang | 2019 | Journal of Renewable Materials2019，7，11： | 0 |
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