Crustal S-wave velocity structure across the northeastern South China Sea continental margin: implications for lithology and mantle exhumation

The northeastern margin of the South China Sea (SCS), developed from continental rifting and breakup, is usually thought of as a non-volcanic margin. However, post-spreading volcanism is massive and lower crustal high-velocity anomalies are widespread, which complicate the nature of the margin here. To better understand crustal seismic velocities, lithology, and geophysical properties, we present an S-wave velocity (VS) model and a VP/VS model for the northeastern margin by using an existing P-wave velocity (VP) model as the starting model for 2-D kinematic S-wave forward ray tracing. The Mesozoic sedimentary sequence has lower VP/VS ratios than the Cenozoic sequence;in between is a main interface of P-S conversion. Two isolated high-velocity zones (HVZ) are found in the lower crust of the continental slope, showing S-wave velocities of 4.0–4.2 km/s and VP/VS ratios of 1.73–1.78. These values indicate a mafic composition, most likely of amphibolite facies. Also, a VP/VS versus VP plot indicates a magnesium-rich gabbro facies from post-spreading mantle melting at temperatures higher than normal. A third high-velocity zone (VP : 7.0–7.8 km/s;VP/VS: 1.85–1.96), 70-km wide and 4-km thick in the continent-ocean transition zone, is most likely to be a consequence of serpentinization of upwelled upper mantle. Seismic velocity structures and also gravity anomalies indicate that mantle upwelling/ serpentinization could be the most severe in the northeasternmost continent-ocean boundary of the SCS. Empirical relationships between seismic velocity and degree of serpentinization suggest that serpentinite content decreases with depth, from 43% in the lower crust to 37% into the mantle.

Thermal structures of the Pacific lithosphere from magnetic anomaly inversion

Of the world's oceans, the Pacific has the most abundant distribution of seamount trails, oceanic plateaus and hot spots, and has the longest fracture zones. However, little is known of their thermal structures due to difficulties of heat flow measurement and interpretation, and in inferring thermal anomalies from low-resolution seismic velocities. Using recently published global magnetic models, we present the first independent constraint on Pacific geothermal state and mantle dynamics, by applying a fractal magnetization inversion model to magnetic anomaly data. Warm thermal anomalies are inferred for all known active hot spots, most seamount trails, some major fracture zones, and oceanic lithosphere between ~100 and ~140 Ma in age. While most Curie points are among the shallowest in the zone roughly bounded by the 20 Ma isochrons, abnormally deep Curie points are found along nearly all ridge crests in the Pacific, related to patchy, long-wavelength and large-amplitude magnetic anomalies that are most likely caused by prevailing magmatic or hydrothermal processes. Many large contrasts in the thermal evolution between the Pacific and North Atlantic support much stronger hydrothermal circulation occurring in Pacific lithospheres younger than ~60 Ma, which may have disguised from surface heat flow any deep thermal signatures of volcanic structures. Yet, at depths of the Curie points, our model argues for warmer Pacific lithosphere for crustal ages older than ~15 Ma, given a slightly higher spatial correlation of magnetization in the Pacific than in the North Atlantic.

Changing trends of clinicopathologic features and survival duration after surgery for gastric cancer in Northeast China

BACKGROUND Through analyzing the data from a single institution in Northeast China,this study revealed the possible clinicopathologic characteristics that influence the prognosis of patients with gastric cancer(GC).AIM To evaluate the changing trends of clinicopathologic features and survival duration after surgery in patients with GC in Northeast China,which is a highprevalence area of GC.METHODS The study analyzed the difference in clinicopathologic features and survival duration after surgery of 5887 patients who were histologically diagnosed with GC at the Harbin Medical University Cancer Hospital.The study mainly analyzed the data in three periods,2000 to 2004(Phase 1),2005 to 2009(Phase 2),and 2010 to 2014(Phase 3).RESULTS Over time,the postoperative survival rate significantly increased from 2000 to 2014.In the past 15 years,compared with Phases 1 and 2,the tumor size was smaller in Phase 3(P<0.001),but the proportion of high-medium differentiated tumors increased(P<0.001).The proportion of early GC gradually increased from 3.9%to 14.4%(P<0.001).A surprising improvement was observed in the mean number of retrieved lymph nodes,ranging from 11.4 to 27.5(P<0.001).The overall 5-year survival rate increased from 24%in Phase 1 to 43.8%in Phase 3.Through multivariate analysis,it was found that age,tumor size,histologic type,tumor-node-metastasis stage,depth of invasion,lymph node metastasis,surgical approach,local infiltration,radical extent,number of retrieved lymph nodes,and age group were independent risk factors that influenced the prognosis of patients with GC.CONCLUSION The clinical features of GC in Northeast China changed during the observation period.The increasing detection of early GC and more standardized surgical treatment effectively prolonged lifetimes.

Gravity modelling of crustal architecture and heterogeneity in the Nansha Block,South China Sea

The stretched structure and heterogeneity of the crust of the Nansha Block,the southern continental margin of the South China Sea(SCS),are not well understood.We used published ocean bottom seismic(OBS)/multichannel reflection seismic(MCS)profiles across the Nansha Block to establish five two-dimensional crustal structure models.Using gravity modelling with magnetic anomaly inversion,we obtained the distribution of density and local magnetic susceptibility of the crust.The models show that the distribution of density and thickness of the upper crust in the Nansha Block is uneven,and the thick upper crust is prevalent in the regions close to the continent-ocean transition(COT)showing different characteristics.The interpreted Mesozoic granite blocks and Precambrian rigid basement reflects the heterogeneity in the material composition of the SCS continental margin.Based on the thinning styles of different crustal layers,we suggest that the Nansha Block has a three-layer thinning pattern.The uppermost pre-rift layer was deformed via brittle fractures,the upper crust was sheared by discrete shear zones,and the lower crust experienced ductile deformation.The inherited pre-rift thermal regime,mechanical state,and material composition of the SCS continental margin affected the extensional structure of the crust.

Ellagic acid inhibits gastric cancer cells by modulating oxidative stress and inducing apoptosis

Objective:To evaluate the anticancer effect of ellagic acid on gastric cancer cells.Methods:MTT assay was used to evaluate the effect of ellagic acid at different concentrations(0.5-100μg/mL)on gastric cancer AGS cells.RT-qPCR and Western blot analyses were applied to assess apoptosis(BCL-2,CASP-3,and BAX)and autophagy(LC3,ATG5,and BECN1)in AGS cells treated with ellagic acid.The expression of invasion-related markers including TP53,CDKN2A,and PTEN was determined.In addition,cell cycle markers including cyclin A,B,D,and E were measured by ELISA.Oxidative stress markers were evaluated using spectrophotometry.Results:Ellagic acid inhibited the proliferation of AGS cells in a concentration-and time-dependent manner.The expression of BCL-2 was significantly decreased(P<0.05)and CASP-3 and BAX were markedly increased(P<0.01)in AGS cells treated with ellagic acid.However,this compound induced no significant changes in the expression levels of LC3,ATG5,and BECN1(P>0.05).Moreover,the oxidative stress markers including SOD,TAC,and MDA were increased by ellagic acid(P<0.01).Conclusions:Ellagic acid can inhibit cell proliferation,induce apoptosis,and modulate oxidative stress in AGS cells.However,further in vivo and molecular studies are needed to verify its anticancer efficacy.

The crustal nature of the northern Mozambique Ridge,Southwest Indian Ocean

The Mozambique Ridge(MOZR)is one of the basement high structures located in the Southwest Indian Ocean,parallel to the Southeast African continental margin.It was formed as a result of the tectono-magmatic evolution of the Gondwana breakup.The origin of the MOZR has been highly debated,with models suggesting either continental or oceanic origin.With new free-air gravity anomaly and multichannel seismic(MCS)reflection data,we present results of 2D density modeling along two seismic profiles acquired by R/V Xiangyanghong 10 at the northern Mozambique Ridge(N-MOZR)between 26°S and 28°S.We observed high free-air gravity anomaly and strong positive magnetic anomaly related to the emplaced seaward dipping reflectors(SDR)and high density lower crustal body(HDLCB),and high Bouguer gravity anomaly associated with the thinning of the continental crust underneath the N-MOZR over a distance of~82 km.This suggests a thinned and intruded continental crust bound by the Mozambique Fracture Zone(MFZ)that is characterized by gravity low and negative magnetic anomaly.This fracture zone marks the continent-ocean boundary(COB)while the N-MOZR is the transform margin high,i.e.,marks the continent-ocean transition(COT)of the Southern Mozambique margin,following the definition of transform margins.We suggest that the N-MOZR was formed by continental extension and subsequent breakup of the MFZ,accompanied by massive volcanism during the southward movement of the Antarctica block.The presence of SDR,HDLCB,and relatively thick oceanic crust indicates the volcanic nature of this transform margin.

Prognostic significance of Borrmann type combined with vessel invasion status in advanced gastric cancer

BACKGROUND Borrmann classification(types I-IV)for the detection of advanced gastric cancer has been accepted worldwide,and lymphatic and/or blood vessel invasion(LBVI)status is related to the poor prognosis after gastric cancer.AIM To evaluate the significance of Borrmann type combined with LBVI status in predicting the prognosis of advanced gastric cancer.METHODS We retrospectively studied the clinicopathological characteristics and long-term survival data of 2604 patients who were diagnosed with advanced gastric adenocarcinoma at Harbin Medical University Cancer Hospital from January 2009 to December 2013.Categorical variables were evaluated by the Pearson’sχ^2 test,the Kaplan-Meier method was used to identify differences in cumulative survival rates,and the Cox proportional hazards model was used for multivariate prognostic analysis.RESULTS A total of 2604 patients were included in this study.The presence of LVBI[LBVI(+)]and Borrmann type(P=0.001),tumor location(P<0.001),tumor size(P<0.001),histological type(P<0.001),tumor invasion depth(P<0.001),number of metastatic lymph nodes(P<0.001),and surgical method(P<0.001)were significantly correlated with survival.When analyzing the combination of the Borrmann classification and LBVI status,we found that patients with Borrmann type Ⅲ disease and LBVI(+)had a similar 5-year survival rate to those with Borrmann IV+LBVI(-)(16.4%vs 13.1%,P=0.065)and those with Borrmann IV+LBVI(+)(16.4%vs 11.2%,P=0.112).Subgroup analysis showed that the above results were true for any pT stage and any tumor location.Multivariate Cox regression analysis showed that Borrmann classification(P=0.023),vascular infiltration(P<0.001),tumor size(P=0.012),pT stage(P<0.001),pN stage(P<0.001),and extent of radical surgery(P<0.001)were independent prognostic factors for survival.CONCLUSION Since patients with Borrmann Ⅲ disease and LBVI(+)have the same poor prognosis as those with Borrmann IV disease,more attention should be paid to patients with Borrmann Ⅲ disease and LBVI(+)during diagnosis and treatment,regardless of the pT stage and tumor location,to obtain better survival results.

南海莺歌海盆地XF13区块不同成分气体充注引起的成岩差异

在油气运移和聚集过程中,充注气体对溶解、胶结和黏土转化的影响尚不清楚。南海莺歌海盆地XF13区块黄流组上部储层为CO2和气态烃充注,为定量研究不同成分充注气体所引起的成岩差异提供了理想的机会。本研究使用的技术和方法包括光学显微镜、扫描电子显微镜、阴极发光、x射线衍射、地层水的化学分析、稳定同位素分析和流体组分检查。分析表明,在底辟带附近的井中,富含CO2的热流体后期充注改变了孔隙度、渗透率、温度、流体pH值及K+、Na+、Mg2+、Fe2+等离子含量。底辟带附近的XF13A井和XF13B井存在高成熟度、高CO2含量的天然气聚集,是幕式混合和改造结果;远离底辟带的井(如XF13E、XF13F)多为烷烃富集。

Wear properties of nonhydrogenated,hydrogenated,and dehydrogenated Ti6A14V alloy

Wear properties of the nonhydrogenated, hydrogenated 0.5 wt%, and dehydrogenated Ti6Al4V alloys were studied through dry sliding wear tests using an M-200 type pin-on-disk wear testing machine in ambient air at room temperature to reveal the effects of hydrogen on wear properties of Ti6Al4V alloy. Morphology and chemical element of worn surface were investigated by means of scanning electron microscope （SEM） and energy dispersive spectroscopy （EDS）. Results show that hydrogen decreases the wear resistance of Ti6Al4V alloy. Wear rate of the Ti6Al4V alloy increases after hydrogenation. Wear rate increases by 244.3 % when 0.5 wt% hydrogen is introduced into a Ti6Al4V alloy. Wear rate of the dehydrogenated Ti6Al4V alloy recovers. Wear mechanisms of the nonhydrogenated, hydrogenated, and dehydrogenated Ti6Al4V alloys are determined. The nonhydrogenated Ti6Al4V alloy is controlled by oxidative wear. The hydrogenated Ti6Al4V alloy is dominated by abrasive wear. Wear mechanism of the dehydrogenated Ti6Al4V alloys is a mixture of oxidative wear and abrasive wear.

Enhancer activity of Hefitron in sericin-1 gene promoter from Bombyx mori

Sericin is a kind of water-soluble protein expressed specifically in the middle silk gland ofBombyx mori. When the sericin-1 gene promoter was cloned and a transgenic vector was constructed to express a foreign protein, a specific Helitron, Bmhel-8, was identified in the sericin-1 gene promoter sequence in some genotypes of Bombyx mori and Bombyx mandarina. Given that the Bmhel-8 Helitron transposon was present only in some genotypes, it could be the source of allelic variation in the sericin-I promoter. The length of the sericin-1 promoter sequence is approximately 1063 or 643 bp. The larger size of the sequence or allele is ascribed to the presence of Bmhel-8. Silkworm genotypes can be homozygous for either the shorter or larger promoter sequence or heterozygous, containing both alleles. Bmhel-8 in the sericin-1 promoter exhibits enhancer activity, as demonstrated by a dual-luciferase reporter system in BraE cell lines. Furthermore, Bmhel-8 displays enhancer activity in a sericin-1 promoter-driven gene expression system but does not regulate the tissue-specific expression of sericin-1.