Evolution of Siderian juvenile crust to Rhyacian high Ba-Sr magmatism in the Mineiro Belt, southern S?o Francisco Craton

Plutonic rocks from the Mineiro Belt, Brazil record a delayed onset of the transition from TTG to sanukitoid-type magmatism（high Ba-Sr）, starting during the Siderian magmatic lull when little juvenile magma was added to the continental crust. Rocks mostly belong to the calc-alkaline series, meta-to peraluminous and originally ＂Ⅰ-type＂,meaning that oxidized magmas were formed by partial melting of subducted material. The temporal distribution and apparent secular changes of the magmas are consistent with the onset of subduction-driven plate tectonics due to an increase of the subduction angle and opening of the mantle wedge. New isotopic analyses（Sm-Nd whole rock and Lu-Hf in zircon）corroborate the restricted juvenile nature of the Mineiro Belt and confirm the genetic link between the Lagoa Dourada Suite,a rare ca. 2350 Ma high-Al tonalite-trondhjemite magmatic event, and the sanukitoid-type ca. 2130 Ma Alto Maranhao Suite. U-Pb dating of zircon and titanite constrain the crystallisation history of plutonic bodies; coupled with major and trace element analyses of the host rocks, they distinguish evolutionary trends in the Mineiro Belt. Several plutons in the region have ages close to 2130 Ma but are distinguished by the lower concentration of compatible elements in the juvenile high Ba-Sr suite.

Paleoproterozoic juvenile magmatism within the northeastern sector of the Sao Francisco paleocontinent:Insights from the shoshonitic high Ba-Sr Montezuma granitoids

New,integrated petrographic,mineral chemistry,whole rock geochemical,zircon and titanite UPb geochronology,and zircon Hf isotopic data from the Montezuma granitoids,as well as new geochemical results for its host rocks represented by the Corrego Tingui Complex,provides new insights into the late-to post-collisional evolution of the northeastern Sao Francisco paleocontinent.U-Pb zircon dates from the Montezuma granitoids spread along the Concordia between ca.2.2 Ga to 1.8 Ga and comprise distinct groups.Group I have crystallization ages between ca.2.15 Ga and 2.05 Ga and are interpreted as inherited grains.Group II zircon dates vary from 2.04 Ga to1.9 Ga and corresponds to the crystallization of the Montezuma granitoids,which were constrained at ca.2.03 Ga by the titanite U-Pb age.Inverse age zoning is common within the ca.1.8 Ga Group III zircon ages,being related to fluid isotopic re-setting during the Espinhaco rifiting event.ZirconεHf(t)analysis show dominantly positive values for both Group I(-4 to+9)andⅡ(-3 to+8)zircons and TDM2 model ages of 2.7-2.1 Ga and 2.5-1.95 Ga,respectively.Geochemically,the Montezuma granitoids are weakly peraluminous to metaluminous magnesian granitoids,enriched in LILES and LREE,with high to moderate Mg#and depleted in some of the HFSE.Their lithochemical signature,added to the juvenile signature of both inherited and crystallized zircons,allowed its classification as a shoshonitic high Ba-Sr granitoid related to a late-to post-collisional lithosphere delamination followed by asthenospheric upwelling.In this scenario,the partial melting of the lithospheric mantle interacted with the roots of an accreted juvenile intra-oceanic arc,being these hybrid magma interpreted as the source of the Montezuma granitoids.The Corrego Tingui Complex host rocks are akin to a syn-to late-collisional volcanic arc granitoids originated from the partial melting of ancient crustal rocks.The results presented in this study have revealed the occurrence of juvenile rocks,probably related to an island arc environment,that are exotic in relation to the Paleo-to Neoarchean crust from the Sao Francisco paleocontinent’s core.

Neoarchean atmospheric chemistry and the preservation of S-MIF in sediments from the São Francisco Craton

Sulfur mass-independent fractionation(S-MIF)preserved in Archean sedimentary pyrite is interpreted to reflect atmospheric chemistry.Small ranges in Δ^(33)S that expanded into larger fractionations leading up to the Great Oxygenation Event(GOE;2.45–2.2 Ga)are disproportionately represented by sequences from the Kaapvaal and Pilbara Cratons.These patterns of S-MIF attenuation and enhancement may differ from the timing and magnitude of minor sulfur isotope fractionations reported from other cratons,thus obscuring local for global sulfur cycling dynamics.By expanding the Δ^(33)S record to include the relatively underrepresented São Francisco Craton in Brazil,we suggest that marine biogeochemistry affected S-MIF preservation prior to the GOE.In an early Neoarchean sequence(2763–2730 Ma)from the Rio das Velhas Greenstone Belt,we propose that low δ^(13)Corg(<-30‰)and dampened Δ^(33)S(-0.4‰to-0.7‰)in banded iron formation reflect the marine diagenetic process of anaerobic methane oxidation.The overlying black shale(TOC up to 7.8%)with higher δ^(13)Corg(-33.4‰to-19.2‰)and expanded Δ^(33)S(2.3‰±0.8‰),recorded oxidative sulfur cycling that resulted in enhance preservation of S-MIF input from atmospheric sources of elemental sulfur.The sequence culminates in a metasandstone,where concomitant changes to more uniform δCorg(-30‰to--25‰),potentially associated with the RuBisCO I enzyme,and near-zero Δ^(33)S(-0.04‰to 0.38‰)is mainly interpreted as evidence for local oxygen production.When placed in the context of other sequences worldwide,the Rio das Velhas helps differentiate the influences of global atmospheric chemistry and local marine diagenesis in Archean biogeochemical processes.Our data suggest that prokaryotic sulfur,iron,and methane cycles might have an underestimated role in pre-GOE sulfur minor isotope records.

Evolution of the 3.65-2.58 Ga Mairi Gneiss Complex,Brazil:Implications for growth of the continental crust in the São Francisco Craton

The composition and formation of the Earth’s primitive continental crust and mantle differentiation are key issues to understand and reconstruct the geodynamic terrestrial evolution,especially during the Archean.However,the scarcity of exposure to these rocks,the complexity of lithological relationships,and the high degree of superimposed deformation,especially with long-lived magmatism,make it difficult to study ancient rocks.Despite this complexity,exposures of the Archean Mairi Gneiss Complex basement unit in the São Francisco Craton offer important information about the evolution of South America’s primitive crust.Therefore,here we present field relationships,LA-ICP-SFMS zircon U-Pb ages,and LA-ICP-MCMS Lu-Hf isotope data for the recently identified Eoarchean to Neoarchean gneisses of the Mairi Complex.The Complex is composed of massive and banded gneisses with mafic members ranging from dioritic to tonalitic,and felsic members ranging from TTG(Tonalite-Trondhjemite-Granodiorite)to granitic composition.Our new data point to several magmatic episodes in the formation of the Mairi Gneiss Complex:Eoarchean(ca.3.65–3.60 Ga),early Paleoarchean(ca.3.55–3.52 Ga),middle-late Paleoarchean(ca.3.49–3.33 Ga)and Neoarchean(ca.2.74–2.58 Ga),with no records of Mesoarchean rocks.Lu-Hf data unveiled a progressive evolution of mantle differentiation and crustal recycling over time.In the Eoarchean,rocks are probably formed by the interaction between the pre-existing crust and juvenile contribution from chondritic to weakly depleted mantle sources,whereas mantle depletion played a role in the Paleoarchean,followed by greater differentiation of the crust with thickening and recycling in the middle–late Paleoarchean.A different stage of crustal growth and recycling dominated the Neoarchean,probably owing to the thickening of the continental crust by collision,continental arc growth,and mantle differentiation.

A perspective on potassic and ultrapotassic rocks:Constraints on the Paleoproterozoic late to post-collisional event in the São Francisco paleocontinent

The late-to post-collisional stage in orogenic systems is characterized by the coeval existence of bimodal potassic to ultrapotassic magmatic activity related to partial melting of an enriched lithospheric mantle together with crustal derived melts.In this paper,we present new whole rock geochemical analyses combined with zircon and titanite U–Pb and zircon Hf isotopic data from potassic to ultrapotassic rocks from six plutons that occur within the Archean Itacambira-Monte Azul block(BIMA),to discuss their petrogenesis and the tectonic implications for the São Francisco paleocontinent.The new U–Pb ages range from ca.2.06 Ga to 1.98 Ga and reveal long-lasting potassic magmatism within the BIMA,which is within the late-to-post-collisional stage of the São Francisco paleocontinent evolution.The ultrapotassic rocks are compatible with a fluid-related metasomatized mantle source enriched by previous subduction events,whereas the potassic rocks are bimodal and have a transitional shoshonitic to A-type affinity.These rocks have a hybrid nature,possible related to the mixing between the mafic potassic/ultrapotassic rocks and high temperature crustal melts of the Archean continental crust.Our results also show an increase of within-plate signature towards the younger potassic magmas.The participation of an important Archean crustal component in the genesis of these rocks is highlighted by the common and occasionally abundant occurrence of Archean inherited zircons.The Hf isotopic record shows that most of the zircon inheritance has dominantly subchondriticεHf(t)values,which fits a crustal reworking derivation from a similar Eo-to Paleoarchean precursor crust.However,the presence of juvenile 2.36 Ga zircon inheritance in an ultrapotassic sample reveal the existence of a hidden reservoir that is somewhat similar to the described for the Mineiro Belt in southern São Francisco paleocontinent.

Chemical-Abrasion U-Pb zircon geochronology reveals 150 Myr of partial melting events in the Archean crust of the São Francisco Craton

Field observations and CA-LA-ICP-MS U–Pb zircon ages and Hf isotope compositions obtained from migmatitic orthogneisses and granitoids from the Belo Horizonte Complex,southern São Francisco Craton,indicate a major period of partial melting and production of felsic rocks in the Neoarchean.Our observations show that the complex is an important site for studying partial melting processes of Archean crystalline crust.Much of the complex exposes fine-grained stromatic migmatites that are intruded by multiple leucogranitic veins and sheeted dikes.Both migmatites and leucogranite sheets are crosscut by several phases of granitoid batholiths and small granitic bodies;both of which are closely associated with the host banded gneisses.Chemical abrasion followed by detailed cathodoluminescence imaging revealed a wide variety of zircon textures that are consistent with a long-lived period of partial melting and crustal remobilization.Results of U-Pb and Hf isotopes disclose the complex as part of a much wider crustal segment,encompassing the entire southern part of the São Francisco Craton.Compilation of available U-Pb ages suggests that this crustal segment was consolidated sometime between 3000 Ma and 2900 Ma and that it experienced three main episodes of partial melting before stabilization at 2600 Ma.The partial melting episodes took place between 2750 Ma and 2600 Ma as a result of tectonic accretion and peeling off the lithospheric mantle and lower crust.This process is likely responsible for the emplacement of voluminous potassic granitoids across the entire São Francisco Craton.We believe that the partial melting of Meso-Archean crystalline crust and production of potassic granitoids are linked to a fundamental shift in the tectonics of the craton,which was also responsible for the widespread intrusion of large syenitic bodies in the northern part of the craton,and the construction of layered mafic–ultramafic intrusions to the south of the BHC.

巴西Sao Francisco水电系统的多用途模型

巴西是一个水资源丰富的国家．90％的电力来自于水发电。巴西水电系统拥有4个子系统，即北部、东北部、东南部和南部，装机总容量6l000MW.Sao Francisco河流域位于巴两东北部，建有7座发电站．3个蓄水库和6个迳流式水库，装机总容量10229MW，是巴西东北部最大的水电系统．Sao Francisco河的流域面积64万km^2，

Archean-Ediacaran evolution of the Campos Gerais Domain-A reworked margin of the São Francisco paleocontinent(SE Brazil):Constraints from metamafic-ultramafic rocks

The Campos Gerais Domain(CGD)in southeastern Brazil is an approximately 180 km×35 km area of Archean–Proterozoic rocks located southwest of the São Francisco Craton(SFC).The Archean–Paleopro terozoic evolution of the CGD—alongside its potential correlation with the SFC or other cratonic blocks in the region-is currently poorly-constrained.We present the results of systematic petrography,bulkrock geochemistry,mineral chemistry and geochronology for a suite of scarcely studied mafic–ultramafic rocks from the CGD.We also provide a compilation of previously reported bulk-rock geochemical and spinel group mineral chemical data for mafic–ultramafic rocks throughout the CGD,and geochronological information for various lithotypes in the region.The CGD records a protracted Mesoarchean to Statherian(3.1–1.7 Ga)crustal evolution,which we interpret to share a common history with the southern SFC and their related reworked segments,suggesting that it is a westward extension of this cratonic terrain.The metavolcano-sedimentary rocks of the Fortaleza de Minas and Alpinópolis segments represent a Mesoarchean greenstone belt that is stratigraphically and chemically comparable to Archean greenstone belts worldwide,and that is broadly coeval with a local suite of tonalite-trondhjemite-grano diorite(TTG)gneisses and migmatites.U-Pb SHRIMP zircon data from a subalkaline metagabbro yielded a concordia age of ca.2.96 Ga,revealing a previously unrecognized phase of Archean magmatism in the CGD that can be chrono-correlated with metakomatiite and TTG generation elsewhere in the São Francisco paleocontinent.Our data contradict a hypothesis whereby the metavolcano-sedimentary rocks of the Jacuí-Bom Jesus da Penha and Petúnia segments represent an ophiolite,as previously suggested,instead presenting features that point to formation in association with a continental arc.Coupled with a U-Pb(SHRIMP)crystallization age of ca.2.13 Ga recorded by zircon grains from a metaultramafic rock,these data highlight that a magmatic event was chrono-correlated with the main accretionary phase of the Minas Orogeny,and with the Pouso Alegre/Amparo and São Vicente complexes.Finally,a U-Pb(SHRIMP)concordia age of ca.590 Ma—obtained from metamorphic-textured zircon grains from a metaultramafic rock—points to a late metamorphic overprint related to upper amphibolite conditions,brittle fault activation and the juxtaposition of crustal blocks in association with the latest stages of western Gondwana’s assembly in the southern SFC,with later retrogression to greenschist-facies.

The Paleoarchean Northern Mundo Novo Greenstone Belt,São Francisco Craton:Geochemistry,U-Pb-Hf-O in zircon and pyriteδ^(34)S-Δ^(33)S-Δ^(36)S signatures

Greenstone belts contain several clues about the evolutionary history of primitive Earth.Here,we describe the volcano-sedimentary rock association exposed along the eastern margin of the Gavião Block,named the Northern Mundo Novo Greenstone Belt(N-MNGB),and present data collected with different techniques,including U–Pb–Hf–O isotopes of zircon and multiple sulfur isotopes(^(32)S,^(33)S,^(34)S,and ^(36)S)of pyrite from this supracrustal sequence.A pillowed metabasalt situated in the upper section of the N-MNGB is 3337±25 Ma old and has zircon with ε_(Hf)(t)=2.47 to1.40,Hf model ages between 3.75 Ga and 3.82 Ga,and δ^(18)O=+3.6‰to+7.3‰.These isotopic data,together with compiled whole-rock trace element data,suggest that the mafic metavolcanic rocks formed in a subduction-related setting,likely a back-arc basin juxtaposed to a continental arc.In this context,the magma interacted with older Eoarchean crustal components from the Gavião Block.Detrital zircons from the overlying quartzites of the Jacobina Group are sourced from Paleoarchean rocks,in accordance with previous studies,yielding a maximum depositional age of 3353±22 Ma.These detrital zircons have ε_(Hf)(t)=5.40 to0.84,Hf model ages between 3.66 Ga and 4.30 Ga,and δ^(18)O=+4.8‰to+6.4‰.The pyrite multiple sulfur isotope investigation of the 3.3 Ga supracrustal rocks from the N-MNGB enabled a further understanding of Paleoarchean sulfur cycling.The samples have diverse isotopic compositions that indicate sulfur sourced from distinct reservoirs.Significantly,they preserve the signal of the anoxic Archean atmosphere,expressed by MIF-S signatures(Δ^(33)S between1.3‰to+1.4‰)and a Δ^(36)S/Δ^(33)S slope of0.81 that is indistinguishable from the so-called Archean array.A BIF sample has a magmatic origin of sulfur,as indicated by the limited Δ^(34)S range(0 to+2‰),Δ^(33)S~0‰,and Δ^(36)S~0‰.A carbonaceous schist shows positive Δ^(34)S(2.1‰–3.5‰)and elevated Δ^(33)S(1.2‰–1.4‰)values,with corresponding negative Δ^(36)S between1.2‰to0.2‰,which resemble the isotopic composition of Archean black shales and suggest a source from the photolytic reduction of elemental sulfur.The pillowed metabasalt displays heterogeneous Δ^(34)S,Δ^(33)S,and Δ^(36)S signatures that reflect assimilation of both magmatic sulfur and photolytic sulfate during hydrothermal seafloor alteration.Lastly,pyrite in a massive sulfide lens is isotopically similar to barite of several Paleoarchean deposits worldwide,which might indicate mass dependent sulfur processing from a global and well-mixed sulfate reservoir at this time.

Precambrian Dykes in the Sao Francisco Craton Revisited:Geochemical-isotopic Signatures and Tectonic Significance

Several generations of mafic dyke swarms(2.7 to 0.8Ga),highlighted by aeromagnetic data,petrography,geochemistry,isotope geology and mostly U-Pb baddeleyite ages,crosscut the Archean and

Seismicity of the San Francisco Volcanic Field of Northern Arizona

Seismicity in northern Arizona is concentrated in a northwest-southeast trending belt that stretches from the Utah border south to the edge of the Colorado Plateau. Located within this NASB （Northern Arizona Seismic Belt） is the San Francisco volcanic field, classified by the United States Geological Survey as potentially active. The last volcanic event in the field was located at Sunset Crater and occurred less than 1,000 years ago. Eruption intervals in the volcanic field are of the same order of length of time. Seismic monitoring of the volcanic field area has improved greatly since 1985 with the establishment of new network seismic stations. This has allowed for a lowered threshold of detection of seismic events and improved location capabilities. As an example of the result of this improved ability to locate smaller tremors, two swarms have been identified in the field, the 2009 Halloween swarm near Sunset Crater volcano and the 2011 swarm near Flagstaff, the largest urban community in northern Arizona.

Determination of Organochlorine Compounds in Sediments from the Upper Middle Sao Francisco River （Bahia, Brazil）

The objective of this study was to determine the contamination of OCPs （organochlorine pesticides） in sediments from the upper middle of Sao Francisco River （Bahia, Brazil） in order to evaluate their potential pollution risks. Samples of surface sediments were collected using a Petersen dredge at 21 stations located between Sobradinho and Cura^i. The organochlorine compounds analyzed were： p,p＇-DDT, p,p＇-DDD, p,p＇-DDE, dicofol, methoxychlor, HCHs, aldrin, endrin, endrin aldehyde, endrin ketone, dieldrin, heptachlor, heptachlor epoxide, endosulfan （ct, fl and sulfate） and chlordane （ct and ,/）. Extractions were carried out using the MAE （microwave-assisted extraction） method and organochlorine pesticides determination was achieved by GC/MS （gas chromatography-mass spectrometry）. Organochlorine concentrations ranged between 1.51-820.00 ng.gx, indicating very low to high levels. The most frequent OCPs were endrin aldehyde, -HCH, HCH, HCH, heptachlor and heptachlor epoxide.

A Case for the Modifiability of the San Francisco Peace Treaty: Examining the Varying Positions of the U.S. and Britain Over South Korean Participation

Through a detailed analysis and documentation of relevant U.S.foreign relations and other official documents of the period around the Korean War,this paper aims to prove that in the early negotiation process of the 1951 San Francisco peace treaty,the United States maintained that South Korea should participate in signing the treaty and that the U.S.changed its position because of the resilient British opposition to South Korean participation,which in turn was motivated strongly by the British concern over its strategic interests in East Asia and its diplomatic relations with the newly communized China.In particular,the Chinese intervention in the Korean War and the communist recapture of Seoul provided the impetus for this shift in the U.S.position that led to the exclusion of South Korea from the treaty.Because the substance of the San Francisco peace treaty was dictated by the exigencies under the Korean War and the Cold War and lacks the“Grotian spirit of international law”underlying the founding of the League of Nations and the United Nations,the San Francisco peace treaty does not contain sufficient merit to be worthy of permanent compliance,which leaves open the possibility of modification in the future.

Spawning induction and fecundity of commercial native fish species from the São Francisco River basin,Brazil,under hatchery conditions

In order to exploit native fish species for aquaculture, basic parameters of artificial reproducetion and estimates of reproductive potential for this fish must be determined to improve hatchery success. We analyze seven Brazilian commercial fish. Spawning was induced using the hypophysation method, with injection of crude carp pituitary extract (CCPE). Characiformes species signaled the spawning time with behavioral alterations (usually circular movements). The time of oocyte extrusion varied from 5.3 ± 0.3 h in Salminus franciscanus to 8.6 ± 0.1 h in Prochilodus argenteus after the second CCPE injection. The greatest diameter of a vitellogenic oocyte was registered for P. argenteus (873.9 ± 122.2 μm) and the smallest was for Pimelodus maculates (465.4 ± 36.3 μm). The diameter of vitellogenic oocytes was very similar among species belonging to the same family. The highest ROI values were registered for Prochilodus costatus(27.0 ± 3.5 μm) and P. argenteus (23.4 ± 3.7 μm), while the lowest values were found in Pseudoplatystoma corruscans (4.6 ± 0.9 μm) and P. maculatus (6.0 ± 1.3 μm). Absolute fecundity (number of oocytes released at spawning) was lowest in P. maculatus and highest in P. corruscans. Relative fecundity (RF) presented a high correlation (r = 0.98 to 0.99) with gonad weight, indicating high efficiency of spawning. The RF also presented a high correlation with body weight (r = 0.88 to 0.97) and total length (r = 0.86 to 0.92). The highest RF was registered for Leporinus obtusidens, and the lowest was for P. corruscans. Released fecundity had a negative correlation with the diameter of vitellogenic oocytes and with the height of the follicular cells, and a positive correlation with the thickness of the zona pelucida. These results indicate that the species studied herein are suitable candidates for aquaculture due to their reproductive and zootechnical characteristics.

巴西圣弗朗西斯科克拉通地质演化与重要成矿作用

【研究目的】本文旨在梳理构建巴西圣弗朗西斯科克拉通构造演化过程,概述与之成矿作用地质背景及矿床成矿系列的耦合关系,并查明典型矿床的时空分布,目的是服务于克拉通演化与成矿理论。【研究方法】本文在中巴合作开展野外地质调查的基础上,结合巴西圣弗朗西斯科克拉通基底太古宙片麻岩和元古代的碎屑岩锆石U-Pb、Sm-Nd同位素年代学等文献资料,初步归纳出圣弗朗西斯科克拉通重大地质构造演化事件和重要成矿作用。【研究结果】圣弗朗西斯科克拉通4个重要地质演化过程:(1)太古宙3.5 Ga前克拉通古陆核与微陆块形成,3.3~2.9 Ga和2.8~2.5 Ga间则由克拉通北区的盖维奥、索布拉迪纽、塞里尼亚和吉基耶等4个古陆核及南区的近圆形古陆核相互碰撞、拼合和绿岩-增生造山岩浆作用而形成稳定的克拉通陆块;(2)2.5~1.9 Ga古元古代泛亚马逊造山岩浆作用;(3)1.78~1.20 Ga克拉通基底隆升与裂谷改造阶段,形成大量基性岩墙群及陆内非造山型岩浆,完成陆块增厚和最终克拉通化;(4)新元古代克拉通边缘经历巴西利亚/泛非运动(0.64~0.54 Ga)改造,又形成巴西利亚等6个活动造山带。圣弗朗西斯科克拉通形成4期重要成矿作用及相应矿床成矿系列:(1)太古宙(2.5 Ga前)形成绿岩型金矿、苏必利尔湖型硅铁建造为主的变质火山-沉积矿床等成矿系列;(2)古元古代早中期(2.5~1.8 Ga)形成与(超)基性岩相关的铜镍钴硫化物矿床、VMS型铅锌银矿床、IOCG等系列矿床;(3)固结纪-中元古代(1.8~1.0 Ga)形成与非造山岩浆作用相关的铌钽矿、铀矿床,与陆内(缘)裂谷型的钒-钛-铁矿床等系列;(4)新元古代(1.0~0.54 Ga)主要形成铁锰矿、砂锡矿及磷矿等矿床,包括古陆缘-浅海沉积环境有关的(冲积)金刚石砂矿等系列矿床。【结论】构建了巴西圣弗朗西斯科克拉通4个重要地质演化过程,相应划分出4期重要成矿作用。

《旧金山对日和约》涉西沙群岛、南沙群岛条款研究

1949年10月1日,中华人民共和国成立,国民党集团退踞台湾地区。1950年6月25日,朝鲜战争爆发,美国政府迅速调整对台湾地区政策,阴谋干涉中国内政。不同于之前草拟的《对日和约》,美国官员重新设计《对日和约》条款。美国国务院不顾中国、苏联等国家对于这些领土条款的明显分歧,一意孤行。1951年9月8日,美国及其他国家在旧金山签署了《对日和约》,其第二条规定日本放弃中国台湾岛、澎湖列岛、西沙群岛、南沙群岛,置这些岛屿的地位于待定状态。这些条文措词模糊,易于被不同的国家为自己的利益做出解释。为了维护其在西太平洋的战略利益,美国政府预留空间,根据情势变迁,制造在南海的领土争议。然而,这改变不了南沙群岛、西沙群岛属于中国领土一部分的事实。

Liver transplantation for hepatocellular carcinoma in India: Are we ready for 2040?

BACKGROUND Liver transplantation(LT)for hepatocellular carcinoma(HCC)has been widely researched and is well established worldwide.The cornerstone of this treatment lies in the various criteria formulated by expert consensus and experience.The variations among the criteria are staggering,and the short-and long-term outcomes are controversial.AIM To study the differences in the current practices of LT for HCC at different centers in India and discuss their clinical implications in the future.METHODS We conducted a survey of major centers in India that performed LT in December 2022.A total of 23 responses were received.The centers were classified as high-and low-volume,and the current trend of care for patients undergoing LT for HCC was noted.RESULTS Of the 23 centers,35%were high volume center(>500 Liver transplants)while 52%were high-volume centers that performed more than 50 transplants/year.Approximately 39%of centers had performed>50 LT for HCC while the percent distribution for HCC in LT patients was 5%–15%in approximately 73%of the patients.Barring a few,most centers were divided equally between University of California,San Francisco(UCSF)and center-specific criteria when choosing patients with HCC for LT,and most(65%)did not have separate transplant criteria for deceased donor LT and living donor LT(LDLT).Most centers(56%)preferred surgical resection over LT for a Child A cirrhosis patient with a resectable 4 cm HCC lesion.Positron-emission tomography-computed tomography(CT)was the modality of choice for metastatic workup in the majority of centers(74%).Downstaging was the preferred option for over 90%of the centers and included transarterial chemoembolization,transarterial radioembolization,stereotactic body radiotherapy and atezolizumab/bevacizumab with varied indications.The alphafetoprotein(AFP)cut-off was used by 74%of centers to decide on transplantation as well as to downstage tumors,even if they met the criteria.The criteria for successful downstaging varied,but most centers conformed to the UCSF or their center-specific criteria for LT,along with the AFP cutoff values.The wait time for LT from downstaging was at least 4–6 wk in all centers.Contrast-enhanced CT was the preferred imaging modality for post-LT surveillance in 52%of the centers.Approximately 65%of the centers preferred to start everolimus between 1 and 3 months post-LT.CONCLUSION The current predicted 5-year survival rate of HCC patients in India is less than 15%.The aim of transplantation is to achieve at least a 60%5-year disease free survival rate,which will provide relief to the prediction of an HCC surge over the next 20 years.The current worldwide criteria(Milan/UCSF)may have a higher 5-year survival(>70%);however,the majority of patients still do not fit these criteria and are dependent on other suboptimal modes of treatment,with much lower survival rates.To make predictions for 2040,we must prepare to arm ourselves with less stringent selection criteria to widen the pool of patients who may undergo transplantation and have a chance of a better outcome.With more advanced technology and better donor outcomes,LDLT will provide a cutting edge in the fight against liver cancer over the next two decades.

弗朗西斯科·皮纳尔《厦门方言语法》韵母系统研究

西班牙传教士弗朗西斯科·皮纳尔所著的《厦门方言语法》(1928)从语音、词汇、语法等角度对厦门方言进行全面系统的分析,重点围绕着语法特征展开。论文着重整理韵母系统:19个元音韵母(包括7个单元音和12个复元音)、15个鼻音韵母、10个鼻化韵母、2个声化韵母、31个入声韵母。《厦门方言语法》对元音的分析没有罗常培《厦门音系》的精细和全面,它的音系与《翻译英华厦腔语汇》《厦荷大辞典》《厦门方言英汉辞典》《厦门话字典补编》等传教士文献比较接近。

The Historical Evolution of Chinese Education in the United States

Chinese education in America is a cultural product of Chinese immigrants to the United States.In 1848,the California Gold Rush attracted many Chinese to the United States,and gradually formed Chinese communities in the local area,and then spontaneously produced Chinese education.At that time,San Francisco Chinatown was the largest Chinatown in the United States,and its Chinese education showed representative characteristics.By studying the origin and development of Chinese education in San Francisco,this paper analyzes the characteristics of Chinese education in the United States,in order to provide experience and reference for contemporary Chinese education in the United States.

唐宋佛画在20世纪初美国博物馆的传播与鉴识

19末至20世纪初,在美国学者恩内斯特·费诺罗萨(Ernest Francisco Fenollosa,1853—1908)的学术引领和号召力推动下,几大美国博物馆纷纷举办了中国美术展览。其间佛教题材的唐宋卷轴画被置于焦点之位,成为理解东方审美、文化的重要载体。这一时期,中国佛画的西传与鉴藏,是中学西渐的重要印证,亦是近代“中国观”嬗变的一个微观缩影。