It is common for datasets to contain both categorical and continuous variables. However, many feature screening methods designed for high-dimensional classification assume that the variables are continuous. This limit...It is common for datasets to contain both categorical and continuous variables. However, many feature screening methods designed for high-dimensional classification assume that the variables are continuous. This limits the applicability of existing methods in handling this complex scenario. To address this issue, we propose a model-free feature screening approach for ultra-high-dimensional multi-classification that can handle both categorical and continuous variables. Our proposed feature screening method utilizes the Maximal Information Coefficient to assess the predictive power of the variables. By satisfying certain regularity conditions, we have proven that our screening procedure possesses the sure screening property and ranking consistency properties. To validate the effectiveness of our approach, we conduct simulation studies and provide real data analysis examples to demonstrate its performance in finite samples. In summary, our proposed method offers a solution for effectively screening features in ultra-high-dimensional datasets with a mixture of categorical and continuous covariates.展开更多
Recent investigations reveal that the ultrahigh-pressure metamorphic (UHPM) rocks in the Donghai region of East China underwent ductile and transitional ductile-brittle structural events during their exhumation. The e...Recent investigations reveal that the ultrahigh-pressure metamorphic (UHPM) rocks in the Donghai region of East China underwent ductile and transitional ductile-brittle structural events during their exhumation. The earlier ductile deformation took place under the condition of amphibolite facies and the later transitional ductile-brittle deformation under the condition of greenschist facies. The hanging walls moved southeastward during both of these two events. The 40Ar/39Ar dating of muscovites from muscovite-plagioclase schists in the Haizhou phosphorous mine, which are structurally overlain by UHPM rocks, yields a plateau age of 218.0±2.9 Ma and isochron age of 219.8Ma, indicating that the earlier event of the ampibolite-facies deformation probably took place about 220 Ma ago. The 40Ar/39Ar dating of oriented amphiboles parallel to the movement direction of the hanging wall on a decollement plane yields a plateau age of 213.1±0.3 Ma and isochron age of 213.4±4.1 Ma, probably representing the age of the later event. The dating of pegmatitic biotites and K-feldspars near the decollement plane from the eastern Fangshan area yield plateau ages of 203.4±0.3 Ma, 203.6±0.4 Ma and 204.8±2.2 Ma, and isochron ages of 204.0±2.0 Ma, 200.6±3.1 Ma and 204.0±5.0 Ma, respectively, implying that the rocks in the studied area had not been cooled down to closing temperature of the dated biotites and K-feldspars until the beginning of the Jurassic (about 204 Ma). The integration of these data with previous chronological ages on the ultrahigh-pressure metamorphism lead to a new inference on the exhumation of the UHPM rocks. The UHPM rocks in the area were exhumed at the rate of 3-4 km/Ma from the mantle (about 80-100 km below the earth's surface at about 240 Ma) to the lower crust (at the depth of about 20-30km at 220 Ma), and at the rate of 1-2 km/Ma to the middle crust (at the depth of about 15 km at 213 Ma), and then at the rate of less than 1 km/Ma to the upper crust about 10 km deep at about 204 Ma.展开更多
In the gneisses from the drillhole ZK2304 of the Donghai area, there have been preserved high- and ultrahigh-pressure metamorphic mineral assemblages, a series of complicated retrogressive textures and relevant metamo...In the gneisses from the drillhole ZK2304 of the Donghai area, there have been preserved high- and ultrahigh-pressure metamorphic mineral assemblages, a series of complicated retrogressive textures and relevant metamorphic reactions. In addition to garnet, jadeititic-clinopyroxene and rutile, other peak stage (M2) minerals in some gneisses include phengite, aragonite and coesite or quartz pseudomorphs after coesite. The typical peak-stage mineral assemblages in gneisses are characterized by garnet + jadeitic-clinopyroxene + rutile + coesite, garnet + jadeitic-clinopyroxene + phengite + rutile ± coesite and garnet + jadeitic-clinopyroxene + aragonite + rutile ± coesite. The grossular content (Gro) in garnet is high and may reach 50. 1 mol%. The SiO2 content of phengite ranges from 54.37% to 54.84% with 3.54-3.57 p.f.u. Quartz pseudomorphs after coesite occur as inclusions in garnet.The gneisses of the Donghai area have been subjected to multistage recrystallization and exhibit a closewise P-T evolutional path characterized by the near-isothermal decompression. The inclusion assemblage (Hb+Ep+Bi+Pl+Qz) within garnet and other minerals has recorded a pre-peak stage (Mi) epidote amphibole fades metamorphic event. High- and ultrahigh-pressure peak metamorphism (M2) took place at T=750-860℃ and P>2.7 GPa. The symplectitic assemblages after garnet, jadeitic-clinopyroxene and rutile imply a near-isothermal decompression metamorphism (M3, M4) during the rapid exhumation. Several lines of evidence of petrography and metamorphic reactions indicate that both gneisses and eclogites have experienced ultrahigh-pressure metamorphism in the Donghai area. This research may be of great significance for an in-depth study of the metamorphism and tectonic evolution in the Su-Lu ultrahigh-pressure metamorphic belt.展开更多
Study practice has proved that the ultrahigh pressure metamorphic rocks iu Dabieshan must have exPerienced botk the retrograde metumorphism and partial melting under decompression and amphibolite-facies conditions dur...Study practice has proved that the ultrahigh pressure metamorphic rocks iu Dabieshan must have exPerienced botk the retrograde metumorphism and partial melting under decompression and amphibolite-facies conditions during their exhumation from mantel depth to lower-middle crust.The retrometamorphism and partial melting of the ultrahigh pressure rocks in association with thermal state changing in the middle-lower crust, under amphibolite-facies conditions, are important physical and chemical processes. It would result in a great detrease in the integrated yield strength, and the enhancement of the de formabilitY or the rocks, promoting the transition from contractional (collision) to extensional defoemational regime. The statement of tbe retrometamorphism and partial melting of the ultrahigh pressure rocks has proved the in-site model for the ultrahigh pressure rocks in Dabieshan. It not only clarifies the evolutiou from the UHP eclogite to the surrounding gneissic rock (so called UHP gueiss) and to the garnet-beariug roliated granites (non-UHP country rocks), but also provides scientific arguments for the establiskment of the dynamic model of the exhumation of UHP metamorphic rocks in Dabiesban. In general, Purely conductive heat transfer from the crust itself is probably insurficient to produce temperature conditions for partial melting, and additional heat sources must have been present during partial melting. We infer that the partial melting and extensional flow are probably driveu by delamination and magmatic underplating of thickeued lithospkeric mantle following the continental oblique collision.展开更多
The Khondalite Belt within the Inner Mongolia Suture Zone (IMSZ) in the North China Craton is a classic example for Paleoproterozoic ultrahigh-temperature (UHT) metamorphism. Here we report new spinel-bearing meta...The Khondalite Belt within the Inner Mongolia Suture Zone (IMSZ) in the North China Craton is a classic example for Paleoproterozoic ultrahigh-temperature (UHT) metamorphism. Here we report new spinel-bearing metapelitic granulites from a new locality at Xumayao within the southern domain of the IMSZ. Petrological studies and thermodynamic modeling of the spinel -- quartz-bearing assemblage shows that these rocks experienced extreme metamorphism at UHT conditions. Spinel occurs in two textural settings:(1) high Xzn(Zn/(Mg + FeH -- Zn) = 0.071--0.232) spinel with perthitic K-feld- spar, sillimanite and quartz in the rock matrix; and (2)low Xzn (0.045-0.070) spinel as inclusions within garnet porphyroblasts in association with quartz and sillimanite. Our phase equilibria modeling indicates two main stages during the metamorphic evolution of these rocks:(l) near-isobaric cooling from 975 ℃ to 875 ℃ around 8 kbar, represented by the formation of garnet porphyroblasts from spinel and quartz; and(2)cooling and decompression from 850 ℃, 8 kbar to below 750 ℃- 6.5 kbar, represented by the break-down of garnet. The spinel + quartz assemblage is considered to have been stable at peak metamorphism, formed through the break-down of cordierite, indi- caring a near isothermal compression process. Our study confirms the regional extent of UHT metamor- phism within the IMSZ associated with the Paleoproterozoic subduction-collision process.展开更多
A synthesis of the petrological characters of granulite facies rocks that contain equilibrium sapphirine + quartz assemblage from two localities (Tonagh Island (TI) and Priestley Peak (PP)) in the Napier Comple...A synthesis of the petrological characters of granulite facies rocks that contain equilibrium sapphirine + quartz assemblage from two localities (Tonagh Island (TI) and Priestley Peak (PP)) in the Napier Complex,East Antarctica,provides unequivocal evidence for extreme crustal metamorphism possibly associated with the collisional orogeny during Neoarchean.The reaction microstructures associated with sapphirine + quartz vary among the samples,probably suggesting different tectonic conditions during the metamorphic evolution.Sapphirine and quartz in TI sample were probably in equilibrium at the peak stage,but now separated by corona of Grt + Sil + Opx suggesting near isobaric cooling after the peak metamorphism,whereas the Spr + Qtz + Sil + Crd + Spl assemblage replaces garnet in PP sample suggesting post-peak decompression.The application of mineral equilibrium modeling in NCKFMASHTO system demonstrated that Spr + Qtz stability is lowered down to 930 ℃ due to small Fe3+ contents in the rocks (mole Fe2O3/(FeO + Fe2O3) =0.02).The TI sample yields a peak p-T range of 950-1100 ℃ and 7.5-11 kbar,followed by cooling toward a retrograde stage of 800-950 ℃ and 8-10 kbar,possibly along a counterclockwise p-T path.In contrast,the peak condition of the PP sample shows 1000-1050 ℃ and >12 kbar,which was followed by the formation ofSpr + Qtz corona around garnet at 930-970 ℃ and 6.7-7.7 kbar,suggesting decompression possibly along a clockwise p-T trajectory.Such contrasting p-T paths are consistent with a recent model on the structural framework of the Napier Complex that correlates the two areas to different crustal blocks.The different p-T paths obtained from the two localities might reflect the difference in the tectonic framework of these rocks within a complex Neoarchean subduction/collision belt.展开更多
We report equilibrium sapphirine + quartz assemblage in biotite-orthopyroxene-garnet granulites from a new locality in Panasapattu of Paderu region in the Eastern Ghats granulite belt, which provide new evidence for ...We report equilibrium sapphirine + quartz assemblage in biotite-orthopyroxene-garnet granulites from a new locality in Panasapattu of Paderu region in the Eastern Ghats granulite belt, which provide new evidence for ultrahigh-temperature (UHT) metamorphism at 1030-1050 ℃ and 10 kbar in this region. The development of migmatitic texture, stabilization of the garnet-orthopyroxene- plagioclase-K-feldspar association, prograde biotite inclusions within garnet and sapphirine as well as sapphirine and cordierite inclusions within garnet in these granulites indicate that the observed peak assemblages probably formed during prograde dehydration melting of a Bt-Sill-Qtz assemblage, and constrain the prograde stage of the p--T path. The core domains of orthopyroxene porphyroblasts have up to w(Al203) 9.6%, which suggest that the temperatures reached up to 1150 ~C suggesting extreme crustal metamorphism. These conditions were also confirmed by the garnet-orthopyroxene thermobar- ometery, which yields a p--T range of 1012--960 ~C and 9.4 kbar. The p--T phase topologies computed using isochemical sections calculated in the model system Na20-CaO-K20--FeO-MgO-A1203-SiO2 --H2O (NCKFMASH) for metapelites, garnet-free sapphirine granulites and garnet-bearing sapphirine granulites match the melt-bearing assemblages observed in these rocks. Isochemical sections constructed in the NCKFMASH system for an average sub-aluminous metapelite bulk composition, and contoured for modal proportions of melt and garnet, as well as for the compositional isopleths of garnet, predict phase and reaction relations that are consistent with those observed in the rocks. Garnet and orthopyroxene contain Ti-rich phlogopite inclusions, suggesting formation by prograde melting reactions at the expense of phlogopite during ultrahigh-temperature conditions. These p--T results underestimate 'peak' condi- tions, in part as a result of the modification of garnet compositions in the domains where some melt was retained. The post-peak evolution is constrained by a succession of melt-present reactions that occur at p 〈 10 kbar, inferred from micro-structural relations among various minerals. After high-temperature decompression from the metamorphic peak, the p--T path followed a near isobaric cooling stage to T 〈 900℃. The UHT rocks investigated in this study occur within a continental collision suture which witnessed prolonged subduction-accretion history prior to the final collision. We correlate the extreme metamorphism and the stabilization of UHT mineral assemblages to heat and volatile input from an upwelled asthenosphere during subduction--collision tectonics in a Proterozoic convergent plate margin.展开更多
Ultrahigh-pressure(UHP) metamorphic rocks are distinctive products of crustal deep subduction,and are mainly exposed in continental subduction-collision terranes. UHP slices of continental crust are usually involved...Ultrahigh-pressure(UHP) metamorphic rocks are distinctive products of crustal deep subduction,and are mainly exposed in continental subduction-collision terranes. UHP slices of continental crust are usually involved in multistage exhumation and partial melting, which has obvious influence on the rheological features of the rocks, and thus significantly affect the dynamic behavior of subducted slices. Moreover,partial melting of UHP rocks have significant influence on element mobility and related isotope behavior within continental subduction zones, which is in turn crucial to chemical differentiation of the continental crust and to crust-mantle interaction.Partial melting can occur before, during or after the peak metamorphism of UHP rocks. Post-peak decompression melting has been better constrained by remelting experiments; however, because of multiple stages of decompression, retrogression and deformation, evidence of former melts in UHP rocks is often erased. Field evidence is among the most reliable criteria to infer partial melting. Glass and nanogranitoid inclusions are generally considered conclusive petrographic evidence. The residual assemblages after melt extraction are also significant to indicate partial melting in some cases. Besides field and petrographic evidence, bulk-rock and zircon trace-element geochemical features are also effective tools for recognizing partial melting of UHP rocks. Phase equilibrium modeling is an important petrological tool that is becoming more and more popular in P-T estimation of the evolution of metamorphic rocks; by taking into account the activity model of silicate melt, it can predict when partial melting occurred if the P-T path of a given rock is provided.UHP silicate melt is commonly leucogranitic and peraluminous in composition with high SiO_2,low MgO, FeO, MnO, TiO_2 and CaO, and variable K_2 O and Na_2 O contents. Mineralogy of nanogranites found in UHP rocks mainly consists of plagioclase + K-feldspar + quartz, plagioclase being commonly albite-rich.Trace element pattern of the melt is characterized by significant enrichment of large ion lithophile elements(LILE), depletion of heavy rare earth elements(HREE) and high field strength elements(HFSE),indicating garnet and rutile stability in the residual assemblage. In eclogites, significant Mg-isotope fractionation occurs between garnet and phengite; therefore, Mg isotopes may become an effective indicator for partial melting of eclogites.展开更多
Coesite inclusions are found in kyanite from the Lanshantou eclogite in the Sulu ultrahigh-pressure (UHP) metamorphic belt. This discovery extends the stable region of kyanite to over 2.4 GPa. As an important UHP meta...Coesite inclusions are found in kyanite from the Lanshantou eclogite in the Sulu ultrahigh-pressure (UHP) metamorphic belt. This discovery extends the stable region of kyanite to over 2.4 GPa. As an important UHP metamorphic belt in China, the Sulu eclogite belt is the product of A-subduction induced by strong compression of the Yellow Sea terrane to the Jiaodong-northereastern Jiangsu terrane during the interaction of the Eurasian plate and Palaeo-Pacific plate in the Indosinian. It stretches about 350 km and contains over 1000 eclogite bodies. Most eclogites in this belt belong to Groups B and C in the classification of Coleman et al., and commonly contain kyanite, while the Lanshantou eclogite belongs to Group A and contains coesite. The MgO, CaO and FeO contents in garnet and pyroxene show regular variation from the core to the rim, which reveals the PTt paths of progressive metamorphism during the Early Mesozoic (240-200 Ma) and retrogressive metamorphism during the Late Mesozoic and Cenozoic exhumation.展开更多
Up to now it is known that almost all ultrahigh-pressure (UHP) metamorphism of non-impact origin occurred in continent-continent collisional orogenic belt, as has been evidenced by many outcrops in the eastern hemisph...Up to now it is known that almost all ultrahigh-pressure (UHP) metamorphism of non-impact origin occurred in continent-continent collisional orogenic belt, as has been evidenced by many outcrops in the eastern hemisphere. UHP metamorphic rocks are represented by coesite- and diamond-bearing eclogites and eclogite facies metamorphic rocks formed at 650-800℃ and 2.6-3.5 GPa, and most of the protoliths of UHP rocks are volcanic-sedimentary sequences of continental crust. From these it may be deduced that deep subduction of continental crust may have occurred. However, UHP rocks are exposed on the surface or occur near the surface now, which implies that they have been exhumed from great depths. The mechanism of deep subduction of continental crust and subsequent exhumation has been a hot topic of the research on continental dynamics, but there are divergent views. The focus of the dispute is how deep continental crust is subducted so that UHP rocks can be formed and what mechanism causes it to be subducted to great depths and again exhumed to the shallow surface. Through an analysis of the continental process and mechanical boundary conditions of the Dabie collisional belt-an UHP metamorphic belt where the largest area of UHP rocks in the world is exposed, this paper discusses the variations of viscous stresses and average pressure in the viscous fluid caused by tectonism with rock physical properties and the contribution of the tectonic stresses to production of UHP. Calculation indicates that the anomalous stress state on the irregular boundary of a continental block may give rise to stress concentration and accumulation at local places (where the compressional stress may be 5-9 times higher than those in their surroundings). The tectonic stresses may account for 20-35% of the total UHP. So we may infer that the HP (nigh-pressure)-UHP rocks in the Dabie Mountains were formed at depths of 60-80 km. Thus the authors propose a new genetic model of UHP rocks-the point-collision model. This model conforms to the basic principles of the mechanics and also to the geologic records and process in the Dabie orogenic belt. It can explain why UHP rocks do nol exist along the entire length of the collisional orogen but occur in some particular positions. The authors also propose that the eastern and western corners of the Himalaya collision zone are typical point-collision areas and that almost all UHP metamorphism of continental crustal rocks occurred in the two particular positions.展开更多
There are four units of high - pressure to ultrahigh - pressure metamorphism extending from south to north across the Tongbai - Dabie Mountains : the epidote- blueschist - fades unit , the low - temperature eclogite f...There are four units of high - pressure to ultrahigh - pressure metamorphism extending from south to north across the Tongbai - Dabie Mountains : the epidote- blueschist - fades unit , the low - temperature eclogite facies unit , the ultrahigh - pressure eclogite facies unit and the medium-temperature eclogite facies unit . The later two units were formed during the Caledonian subduction between the Tongbai - Dabie microplate and the North China plate ;the former two units are the products of Indosinian continental - continental subduction and collision between the Yangtze and the North China plates.展开更多
The Sulu ultra-high pressure(UHP)metamorphic belt in Eastern China is well known as the eastern extension of the Qingling-Dabie orogenic belt formed by subduction and collision between the Sino-Korean and Yangtze crat...The Sulu ultra-high pressure(UHP)metamorphic belt in Eastern China is well known as the eastern extension of the Qingling-Dabie orogenic belt formed by subduction and collision between the Sino-Korean and Yangtze cratons.The main hole of the Chinese Continental Scientific Drilling(CCSD)project is located at the southern segment of the Sulu UHP metamorphic belt(34°25′N/118°40′E),about 17 km southwest of Donghai County.Integrated geophysical investigations using gravity,magnetic,deep展开更多
A wealth of retrogressive microstructures have been discovered from the UHP metamorphic rocks in Dabie orogenic belt, namely, the ultrahigh-pressure (URP) eclogites, jadeite quartzites and kyanite-zoisite-quartz vein....A wealth of retrogressive microstructures have been discovered from the UHP metamorphic rocks in Dabie orogenic belt, namely, the ultrahigh-pressure (URP) eclogites, jadeite quartzites and kyanite-zoisite-quartz vein. The most important are pseudomorphic replacements of UHP minerals like coesite, the corona reaction textures iuduced by solid-solid reactions as well as the corona and symplectites induced by reactions involving fluid. According to the textural relationships the sequence of mineral Paragenesis and the metamorphic stages in the UHP eclogites can be delineated; the mineral geobarothermometry of the various stages of retrograde metamorphism is studied and a clockwise, nearly isothermal decompressive metamorphic PT-trajectory for the UHP eclogites can be reconstructed. In terms of the PT-trajectory the two stage post collision uplirt and exhumation processes are reflected. When the UHP metumorphic rocks extruded to the lower-middle crust partial melting happened which bad in turn caused tke crustal extension and the further exhumation or the UHP metomorphic rocks. Based on the field strain analysis combined with geochronological data a scenario or post collision uplift aud exhumation model is presented.展开更多
The three stages in the hot-drawing process of ultrahigh-molecular-weight polyethylene gel films can be detected by x-ray diffraction, infrared spectroscopy, birefringence and scanning electron microscopy. In the firs...The three stages in the hot-drawing process of ultrahigh-molecular-weight polyethylene gel films can be detected by x-ray diffraction, infrared spectroscopy, birefringence and scanning electron microscopy. In the first stage of the drawing process, the lamellae in the gel films rotate and/or slip with the b-axis preferentially perpendicular to the drawing direction. With increased drawing, the c-axis of the lamellae become parallel to the stretching direction while unfolding of the chain begins, and the chains of the amorphous phase also orient along the drawing direction in the strain-chain domain. When the draw ratio is large enough, the lamellar structure is transformed into a fibrillar structure in a two-dimensional fashion.展开更多
Increasing demands for ultrahigh-strength steels in commercial as well as military applications have raised interest in finding alternatives to the high-cost high-alloyed steel and super-alloys currently used, e.g. th...Increasing demands for ultrahigh-strength steels in commercial as well as military applications have raised interest in finding alternatives to the high-cost high-alloyed steel and super-alloys currently used, e.g. the use of economic low-alloy compositions processed via low-cost air induction melting and electroslag refining (ESR). In this work the yield of alloying elements and the removal of the impurities nitrogen, sulphur and phosphorus as a result of electroslag refining (ESR) in a newly developed CrNiMoWMnV ultrahigh-strength steel (UHSS) have been studied in relation to their activities in the molten metal pool. Six experimental heats of CrNiMoWMnV UHSS with different chemical compositions were designed, melted in an induction furnace (IF) and refined using ESR. This was followed by hot forging of the ingots at 1100°C to 950°C. ESR using a CaF2-CaO-Al2O3 slag system led to a high yield in Cr, Ni, Mo, W, Mn and V, while the yield of Si is low. The desulphurization of all six UHSS grades was pronounced with most of the sulphur removed either to the slag or by gas reactions. The degree of dephosphorization was only 5% irrespective of the steel composition. On the other hand, denitrification (removal of nitrogen) was achieved. It ranged from 8% to 63% depending on the steel composition. The yield of the alloying elements and removal of impurities from the steel during ESR depends on the chemical and physical properties of the ESR slag and the activity of the elements in the molten state, taking into account elemental interactions.展开更多
It is quite common that both categorical and continuous covariates appear in the data. But, most feature screening methods for ultrahigh-dimensional classification assume the covariates are continuous. And applicable ...It is quite common that both categorical and continuous covariates appear in the data. But, most feature screening methods for ultrahigh-dimensional classification assume the covariates are continuous. And applicable feature screening method is very limited;to handle this non-trivial situation, we propose a model-free feature screening for ultrahigh-dimensional multi-classification with both categorical and continuous covariates. The proposed feature screening method will be based on Gini impurity to evaluate the prediction power of covariates. Under certain regularity conditions, it is proved that the proposed screening procedure possesses the sure screening property and ranking consistency properties. We demonstrate the finite sample performance of the proposed procedure by simulation studies and illustrate using real data analysis.展开更多
The standards of plant toxins were separated by a C18 column with gradient elution with 0.1% formic acid/water (V/V) and 0.1% formic acid/acetonitrile (V/V) as mobile phase and acquired by ion mobility-quadrupole time...The standards of plant toxins were separated by a C18 column with gradient elution with 0.1% formic acid/water (V/V) and 0.1% formic acid/acetonitrile (V/V) as mobile phase and acquired by ion mobility-quadrupole time of flight mass spectrometry (IM-QTOF MS) in positive ion mode. A database of 308 plant toxins including retention time, collision cross-section (CCS) and its fragment ions was established. Honey dissolved in water or herbal beverage was extracted by acetonitrile and purified with PSA sorbent, and then acquired by ultrahigh-performance liquid chromatography IM-QTOFMS. The acquired data were processed by comparing with the database we established to confirm the target compounds. The average recoveries for samples at two levels ranged from 60.6% - 120.1%, with relative standard deviation (n = 6) less than 25%. The limit of quantitation for plant toxins ranged from 1 - 20 μg/kg. The developed screening method was used in determination of honey, herbal beverage and honey flavored tea beverage samples. The results showed that berberine was detected in one honey with 1 μg/kg and caffeine was present in some beverages with the concentration from 200 and 5500 μg/kg. This method could meet the requirement for rapid screening of plant toxins in honey and herbal beverage. It can be used for the quality control of honey and herbal beverage in enterprises or quality inspection departments. It also can be used in the rapid screening of food poisoning.展开更多
Many modern biomedical studies have yielded survival data with high-throughput predictors.The goals of scientific research often lie in identifying predictive biomarkers,understanding biological mechanisms and making ...Many modern biomedical studies have yielded survival data with high-throughput predictors.The goals of scientific research often lie in identifying predictive biomarkers,understanding biological mechanisms and making accurate and precise predictions.Variable screening is a crucial first step in achieving these goals.This work conducts a selective review of feature screening procedures for survival data with ultrahigh dimensional covariates.We present the main methodologies,along with the key conditions that ensure sure screening properties.The practical utility of these methods is examined via extensive simulations.We conclude the review with some future opportunities in this field.展开更多
文摘It is common for datasets to contain both categorical and continuous variables. However, many feature screening methods designed for high-dimensional classification assume that the variables are continuous. This limits the applicability of existing methods in handling this complex scenario. To address this issue, we propose a model-free feature screening approach for ultra-high-dimensional multi-classification that can handle both categorical and continuous variables. Our proposed feature screening method utilizes the Maximal Information Coefficient to assess the predictive power of the variables. By satisfying certain regularity conditions, we have proven that our screening procedure possesses the sure screening property and ranking consistency properties. To validate the effectiveness of our approach, we conduct simulation studies and provide real data analysis examples to demonstrate its performance in finite samples. In summary, our proposed method offers a solution for effectively screening features in ultra-high-dimensional datasets with a mixture of categorical and continuous covariates.
文摘Recent investigations reveal that the ultrahigh-pressure metamorphic (UHPM) rocks in the Donghai region of East China underwent ductile and transitional ductile-brittle structural events during their exhumation. The earlier ductile deformation took place under the condition of amphibolite facies and the later transitional ductile-brittle deformation under the condition of greenschist facies. The hanging walls moved southeastward during both of these two events. The 40Ar/39Ar dating of muscovites from muscovite-plagioclase schists in the Haizhou phosphorous mine, which are structurally overlain by UHPM rocks, yields a plateau age of 218.0±2.9 Ma and isochron age of 219.8Ma, indicating that the earlier event of the ampibolite-facies deformation probably took place about 220 Ma ago. The 40Ar/39Ar dating of oriented amphiboles parallel to the movement direction of the hanging wall on a decollement plane yields a plateau age of 213.1±0.3 Ma and isochron age of 213.4±4.1 Ma, probably representing the age of the later event. The dating of pegmatitic biotites and K-feldspars near the decollement plane from the eastern Fangshan area yield plateau ages of 203.4±0.3 Ma, 203.6±0.4 Ma and 204.8±2.2 Ma, and isochron ages of 204.0±2.0 Ma, 200.6±3.1 Ma and 204.0±5.0 Ma, respectively, implying that the rocks in the studied area had not been cooled down to closing temperature of the dated biotites and K-feldspars until the beginning of the Jurassic (about 204 Ma). The integration of these data with previous chronological ages on the ultrahigh-pressure metamorphism lead to a new inference on the exhumation of the UHPM rocks. The UHPM rocks in the area were exhumed at the rate of 3-4 km/Ma from the mantle (about 80-100 km below the earth's surface at about 240 Ma) to the lower crust (at the depth of about 20-30km at 220 Ma), and at the rate of 1-2 km/Ma to the middle crust (at the depth of about 15 km at 213 Ma), and then at the rate of less than 1 km/Ma to the upper crust about 10 km deep at about 204 Ma.
文摘In the gneisses from the drillhole ZK2304 of the Donghai area, there have been preserved high- and ultrahigh-pressure metamorphic mineral assemblages, a series of complicated retrogressive textures and relevant metamorphic reactions. In addition to garnet, jadeititic-clinopyroxene and rutile, other peak stage (M2) minerals in some gneisses include phengite, aragonite and coesite or quartz pseudomorphs after coesite. The typical peak-stage mineral assemblages in gneisses are characterized by garnet + jadeitic-clinopyroxene + rutile + coesite, garnet + jadeitic-clinopyroxene + phengite + rutile ± coesite and garnet + jadeitic-clinopyroxene + aragonite + rutile ± coesite. The grossular content (Gro) in garnet is high and may reach 50. 1 mol%. The SiO2 content of phengite ranges from 54.37% to 54.84% with 3.54-3.57 p.f.u. Quartz pseudomorphs after coesite occur as inclusions in garnet.The gneisses of the Donghai area have been subjected to multistage recrystallization and exhibit a closewise P-T evolutional path characterized by the near-isothermal decompression. The inclusion assemblage (Hb+Ep+Bi+Pl+Qz) within garnet and other minerals has recorded a pre-peak stage (Mi) epidote amphibole fades metamorphic event. High- and ultrahigh-pressure peak metamorphism (M2) took place at T=750-860℃ and P>2.7 GPa. The symplectitic assemblages after garnet, jadeitic-clinopyroxene and rutile imply a near-isothermal decompression metamorphism (M3, M4) during the rapid exhumation. Several lines of evidence of petrography and metamorphic reactions indicate that both gneisses and eclogites have experienced ultrahigh-pressure metamorphism in the Donghai area. This research may be of great significance for an in-depth study of the metamorphism and tectonic evolution in the Su-Lu ultrahigh-pressure metamorphic belt.
文摘Study practice has proved that the ultrahigh pressure metamorphic rocks iu Dabieshan must have exPerienced botk the retrograde metumorphism and partial melting under decompression and amphibolite-facies conditions during their exhumation from mantel depth to lower-middle crust.The retrometamorphism and partial melting of the ultrahigh pressure rocks in association with thermal state changing in the middle-lower crust, under amphibolite-facies conditions, are important physical and chemical processes. It would result in a great detrease in the integrated yield strength, and the enhancement of the de formabilitY or the rocks, promoting the transition from contractional (collision) to extensional defoemational regime. The statement of tbe retrometamorphism and partial melting of the ultrahigh pressure rocks has proved the in-site model for the ultrahigh pressure rocks in Dabieshan. It not only clarifies the evolutiou from the UHP eclogite to the surrounding gneissic rock (so called UHP gueiss) and to the garnet-beariug roliated granites (non-UHP country rocks), but also provides scientific arguments for the establiskment of the dynamic model of the exhumation of UHP metamorphic rocks in Dabiesban. In general, Purely conductive heat transfer from the crust itself is probably insurficient to produce temperature conditions for partial melting, and additional heat sources must have been present during partial melting. We infer that the partial melting and extensional flow are probably driveu by delamination and magmatic underplating of thickeued lithospkeric mantle following the continental oblique collision.
文摘The Khondalite Belt within the Inner Mongolia Suture Zone (IMSZ) in the North China Craton is a classic example for Paleoproterozoic ultrahigh-temperature (UHT) metamorphism. Here we report new spinel-bearing metapelitic granulites from a new locality at Xumayao within the southern domain of the IMSZ. Petrological studies and thermodynamic modeling of the spinel -- quartz-bearing assemblage shows that these rocks experienced extreme metamorphism at UHT conditions. Spinel occurs in two textural settings:(1) high Xzn(Zn/(Mg + FeH -- Zn) = 0.071--0.232) spinel with perthitic K-feld- spar, sillimanite and quartz in the rock matrix; and (2)low Xzn (0.045-0.070) spinel as inclusions within garnet porphyroblasts in association with quartz and sillimanite. Our phase equilibria modeling indicates two main stages during the metamorphic evolution of these rocks:(l) near-isobaric cooling from 975 ℃ to 875 ℃ around 8 kbar, represented by the formation of garnet porphyroblasts from spinel and quartz; and(2)cooling and decompression from 850 ℃, 8 kbar to below 750 ℃- 6.5 kbar, represented by the break-down of garnet. The spinel + quartz assemblage is considered to have been stable at peak metamorphism, formed through the break-down of cordierite, indi- caring a near isothermal compression process. Our study confirms the regional extent of UHT metamor- phism within the IMSZ associated with the Paleoproterozoic subduction-collision process.
基金Partial funding for this project was produced a Grant-in-Aid for Scientifc Research (B) from Japan Society for the Promotion of Science (JSPS) to Tsunogae(Nos.20340148,22403017)a Grant-in-Aid for JSPS Fellows to Shimizu (No.23-311)
文摘A synthesis of the petrological characters of granulite facies rocks that contain equilibrium sapphirine + quartz assemblage from two localities (Tonagh Island (TI) and Priestley Peak (PP)) in the Napier Complex,East Antarctica,provides unequivocal evidence for extreme crustal metamorphism possibly associated with the collisional orogeny during Neoarchean.The reaction microstructures associated with sapphirine + quartz vary among the samples,probably suggesting different tectonic conditions during the metamorphic evolution.Sapphirine and quartz in TI sample were probably in equilibrium at the peak stage,but now separated by corona of Grt + Sil + Opx suggesting near isobaric cooling after the peak metamorphism,whereas the Spr + Qtz + Sil + Crd + Spl assemblage replaces garnet in PP sample suggesting post-peak decompression.The application of mineral equilibrium modeling in NCKFMASHTO system demonstrated that Spr + Qtz stability is lowered down to 930 ℃ due to small Fe3+ contents in the rocks (mole Fe2O3/(FeO + Fe2O3) =0.02).The TI sample yields a peak p-T range of 950-1100 ℃ and 7.5-11 kbar,followed by cooling toward a retrograde stage of 800-950 ℃ and 8-10 kbar,possibly along a counterclockwise p-T path.In contrast,the peak condition of the PP sample shows 1000-1050 ℃ and >12 kbar,which was followed by the formation ofSpr + Qtz corona around garnet at 930-970 ℃ and 6.7-7.7 kbar,suggesting decompression possibly along a clockwise p-T trajectory.Such contrasting p-T paths are consistent with a recent model on the structural framework of the Napier Complex that correlates the two areas to different crustal blocks.The different p-T paths obtained from the two localities might reflect the difference in the tectonic framework of these rocks within a complex Neoarchean subduction/collision belt.
文摘We report equilibrium sapphirine + quartz assemblage in biotite-orthopyroxene-garnet granulites from a new locality in Panasapattu of Paderu region in the Eastern Ghats granulite belt, which provide new evidence for ultrahigh-temperature (UHT) metamorphism at 1030-1050 ℃ and 10 kbar in this region. The development of migmatitic texture, stabilization of the garnet-orthopyroxene- plagioclase-K-feldspar association, prograde biotite inclusions within garnet and sapphirine as well as sapphirine and cordierite inclusions within garnet in these granulites indicate that the observed peak assemblages probably formed during prograde dehydration melting of a Bt-Sill-Qtz assemblage, and constrain the prograde stage of the p--T path. The core domains of orthopyroxene porphyroblasts have up to w(Al203) 9.6%, which suggest that the temperatures reached up to 1150 ~C suggesting extreme crustal metamorphism. These conditions were also confirmed by the garnet-orthopyroxene thermobar- ometery, which yields a p--T range of 1012--960 ~C and 9.4 kbar. The p--T phase topologies computed using isochemical sections calculated in the model system Na20-CaO-K20--FeO-MgO-A1203-SiO2 --H2O (NCKFMASH) for metapelites, garnet-free sapphirine granulites and garnet-bearing sapphirine granulites match the melt-bearing assemblages observed in these rocks. Isochemical sections constructed in the NCKFMASH system for an average sub-aluminous metapelite bulk composition, and contoured for modal proportions of melt and garnet, as well as for the compositional isopleths of garnet, predict phase and reaction relations that are consistent with those observed in the rocks. Garnet and orthopyroxene contain Ti-rich phlogopite inclusions, suggesting formation by prograde melting reactions at the expense of phlogopite during ultrahigh-temperature conditions. These p--T results underestimate 'peak' condi- tions, in part as a result of the modification of garnet compositions in the domains where some melt was retained. The post-peak evolution is constrained by a succession of melt-present reactions that occur at p 〈 10 kbar, inferred from micro-structural relations among various minerals. After high-temperature decompression from the metamorphic peak, the p--T path followed a near isobaric cooling stage to T 〈 900℃. The UHT rocks investigated in this study occur within a continental collision suture which witnessed prolonged subduction-accretion history prior to the final collision. We correlate the extreme metamorphism and the stabilization of UHT mineral assemblages to heat and volatile input from an upwelled asthenosphere during subduction--collision tectonics in a Proterozoic convergent plate margin.
基金financially supported by the National Basic Research Program of China (Grant No. 2015CB856104)the National Natural Science Foundation of China (Grant No. 41273036)
文摘Ultrahigh-pressure(UHP) metamorphic rocks are distinctive products of crustal deep subduction,and are mainly exposed in continental subduction-collision terranes. UHP slices of continental crust are usually involved in multistage exhumation and partial melting, which has obvious influence on the rheological features of the rocks, and thus significantly affect the dynamic behavior of subducted slices. Moreover,partial melting of UHP rocks have significant influence on element mobility and related isotope behavior within continental subduction zones, which is in turn crucial to chemical differentiation of the continental crust and to crust-mantle interaction.Partial melting can occur before, during or after the peak metamorphism of UHP rocks. Post-peak decompression melting has been better constrained by remelting experiments; however, because of multiple stages of decompression, retrogression and deformation, evidence of former melts in UHP rocks is often erased. Field evidence is among the most reliable criteria to infer partial melting. Glass and nanogranitoid inclusions are generally considered conclusive petrographic evidence. The residual assemblages after melt extraction are also significant to indicate partial melting in some cases. Besides field and petrographic evidence, bulk-rock and zircon trace-element geochemical features are also effective tools for recognizing partial melting of UHP rocks. Phase equilibrium modeling is an important petrological tool that is becoming more and more popular in P-T estimation of the evolution of metamorphic rocks; by taking into account the activity model of silicate melt, it can predict when partial melting occurred if the P-T path of a given rock is provided.UHP silicate melt is commonly leucogranitic and peraluminous in composition with high SiO_2,low MgO, FeO, MnO, TiO_2 and CaO, and variable K_2 O and Na_2 O contents. Mineralogy of nanogranites found in UHP rocks mainly consists of plagioclase + K-feldspar + quartz, plagioclase being commonly albite-rich.Trace element pattern of the melt is characterized by significant enrichment of large ion lithophile elements(LILE), depletion of heavy rare earth elements(HREE) and high field strength elements(HFSE),indicating garnet and rutile stability in the residual assemblage. In eclogites, significant Mg-isotope fractionation occurs between garnet and phengite; therefore, Mg isotopes may become an effective indicator for partial melting of eclogites.
文摘Coesite inclusions are found in kyanite from the Lanshantou eclogite in the Sulu ultrahigh-pressure (UHP) metamorphic belt. This discovery extends the stable region of kyanite to over 2.4 GPa. As an important UHP metamorphic belt in China, the Sulu eclogite belt is the product of A-subduction induced by strong compression of the Yellow Sea terrane to the Jiaodong-northereastern Jiangsu terrane during the interaction of the Eurasian plate and Palaeo-Pacific plate in the Indosinian. It stretches about 350 km and contains over 1000 eclogite bodies. Most eclogites in this belt belong to Groups B and C in the classification of Coleman et al., and commonly contain kyanite, while the Lanshantou eclogite belongs to Group A and contains coesite. The MgO, CaO and FeO contents in garnet and pyroxene show regular variation from the core to the rim, which reveals the PTt paths of progressive metamorphism during the Early Mesozoic (240-200 Ma) and retrogressive metamorphism during the Late Mesozoic and Cenozoic exhumation.
基金the keyfundamentalgeologicalresearch project (No.9501102-3) the Ninth Five-Year Plan supported by the Ministry of Land and Resources a projectsupported by National Natural Science Foundation ofChina grant 19972064.
文摘Up to now it is known that almost all ultrahigh-pressure (UHP) metamorphism of non-impact origin occurred in continent-continent collisional orogenic belt, as has been evidenced by many outcrops in the eastern hemisphere. UHP metamorphic rocks are represented by coesite- and diamond-bearing eclogites and eclogite facies metamorphic rocks formed at 650-800℃ and 2.6-3.5 GPa, and most of the protoliths of UHP rocks are volcanic-sedimentary sequences of continental crust. From these it may be deduced that deep subduction of continental crust may have occurred. However, UHP rocks are exposed on the surface or occur near the surface now, which implies that they have been exhumed from great depths. The mechanism of deep subduction of continental crust and subsequent exhumation has been a hot topic of the research on continental dynamics, but there are divergent views. The focus of the dispute is how deep continental crust is subducted so that UHP rocks can be formed and what mechanism causes it to be subducted to great depths and again exhumed to the shallow surface. Through an analysis of the continental process and mechanical boundary conditions of the Dabie collisional belt-an UHP metamorphic belt where the largest area of UHP rocks in the world is exposed, this paper discusses the variations of viscous stresses and average pressure in the viscous fluid caused by tectonism with rock physical properties and the contribution of the tectonic stresses to production of UHP. Calculation indicates that the anomalous stress state on the irregular boundary of a continental block may give rise to stress concentration and accumulation at local places (where the compressional stress may be 5-9 times higher than those in their surroundings). The tectonic stresses may account for 20-35% of the total UHP. So we may infer that the HP (nigh-pressure)-UHP rocks in the Dabie Mountains were formed at depths of 60-80 km. Thus the authors propose a new genetic model of UHP rocks-the point-collision model. This model conforms to the basic principles of the mechanics and also to the geologic records and process in the Dabie orogenic belt. It can explain why UHP rocks do nol exist along the entire length of the collisional orogen but occur in some particular positions. The authors also propose that the eastern and western corners of the Himalaya collision zone are typical point-collision areas and that almost all UHP metamorphism of continental crustal rocks occurred in the two particular positions.
基金The study is sponsored by the key project of National Natural Sci-ence Foundation of China and the Laboratory of Crust-Mantle Constitution, Recycling and Dynamics
文摘There are four units of high - pressure to ultrahigh - pressure metamorphism extending from south to north across the Tongbai - Dabie Mountains : the epidote- blueschist - fades unit , the low - temperature eclogite facies unit , the ultrahigh - pressure eclogite facies unit and the medium-temperature eclogite facies unit . The later two units were formed during the Caledonian subduction between the Tongbai - Dabie microplate and the North China plate ;the former two units are the products of Indosinian continental - continental subduction and collision between the Yangtze and the North China plates.
文摘The Sulu ultra-high pressure(UHP)metamorphic belt in Eastern China is well known as the eastern extension of the Qingling-Dabie orogenic belt formed by subduction and collision between the Sino-Korean and Yangtze cratons.The main hole of the Chinese Continental Scientific Drilling(CCSD)project is located at the southern segment of the Sulu UHP metamorphic belt(34°25′N/118°40′E),about 17 km southwest of Donghai County.Integrated geophysical investigations using gravity,magnetic,deep
文摘A wealth of retrogressive microstructures have been discovered from the UHP metamorphic rocks in Dabie orogenic belt, namely, the ultrahigh-pressure (URP) eclogites, jadeite quartzites and kyanite-zoisite-quartz vein. The most important are pseudomorphic replacements of UHP minerals like coesite, the corona reaction textures iuduced by solid-solid reactions as well as the corona and symplectites induced by reactions involving fluid. According to the textural relationships the sequence of mineral Paragenesis and the metamorphic stages in the UHP eclogites can be delineated; the mineral geobarothermometry of the various stages of retrograde metamorphism is studied and a clockwise, nearly isothermal decompressive metamorphic PT-trajectory for the UHP eclogites can be reconstructed. In terms of the PT-trajectory the two stage post collision uplirt and exhumation processes are reflected. When the UHP metumorphic rocks extruded to the lower-middle crust partial melting happened which bad in turn caused tke crustal extension and the further exhumation or the UHP metomorphic rocks. Based on the field strain analysis combined with geochronological data a scenario or post collision uplift aud exhumation model is presented.
文摘The three stages in the hot-drawing process of ultrahigh-molecular-weight polyethylene gel films can be detected by x-ray diffraction, infrared spectroscopy, birefringence and scanning electron microscopy. In the first stage of the drawing process, the lamellae in the gel films rotate and/or slip with the b-axis preferentially perpendicular to the drawing direction. With increased drawing, the c-axis of the lamellae become parallel to the stretching direction while unfolding of the chain begins, and the chains of the amorphous phase also orient along the drawing direction in the strain-chain domain. When the draw ratio is large enough, the lamellar structure is transformed into a fibrillar structure in a two-dimensional fashion.
文摘Increasing demands for ultrahigh-strength steels in commercial as well as military applications have raised interest in finding alternatives to the high-cost high-alloyed steel and super-alloys currently used, e.g. the use of economic low-alloy compositions processed via low-cost air induction melting and electroslag refining (ESR). In this work the yield of alloying elements and the removal of the impurities nitrogen, sulphur and phosphorus as a result of electroslag refining (ESR) in a newly developed CrNiMoWMnV ultrahigh-strength steel (UHSS) have been studied in relation to their activities in the molten metal pool. Six experimental heats of CrNiMoWMnV UHSS with different chemical compositions were designed, melted in an induction furnace (IF) and refined using ESR. This was followed by hot forging of the ingots at 1100°C to 950°C. ESR using a CaF2-CaO-Al2O3 slag system led to a high yield in Cr, Ni, Mo, W, Mn and V, while the yield of Si is low. The desulphurization of all six UHSS grades was pronounced with most of the sulphur removed either to the slag or by gas reactions. The degree of dephosphorization was only 5% irrespective of the steel composition. On the other hand, denitrification (removal of nitrogen) was achieved. It ranged from 8% to 63% depending on the steel composition. The yield of the alloying elements and removal of impurities from the steel during ESR depends on the chemical and physical properties of the ESR slag and the activity of the elements in the molten state, taking into account elemental interactions.
文摘It is quite common that both categorical and continuous covariates appear in the data. But, most feature screening methods for ultrahigh-dimensional classification assume the covariates are continuous. And applicable feature screening method is very limited;to handle this non-trivial situation, we propose a model-free feature screening for ultrahigh-dimensional multi-classification with both categorical and continuous covariates. The proposed feature screening method will be based on Gini impurity to evaluate the prediction power of covariates. Under certain regularity conditions, it is proved that the proposed screening procedure possesses the sure screening property and ranking consistency properties. We demonstrate the finite sample performance of the proposed procedure by simulation studies and illustrate using real data analysis.
文摘The standards of plant toxins were separated by a C18 column with gradient elution with 0.1% formic acid/water (V/V) and 0.1% formic acid/acetonitrile (V/V) as mobile phase and acquired by ion mobility-quadrupole time of flight mass spectrometry (IM-QTOF MS) in positive ion mode. A database of 308 plant toxins including retention time, collision cross-section (CCS) and its fragment ions was established. Honey dissolved in water or herbal beverage was extracted by acetonitrile and purified with PSA sorbent, and then acquired by ultrahigh-performance liquid chromatography IM-QTOFMS. The acquired data were processed by comparing with the database we established to confirm the target compounds. The average recoveries for samples at two levels ranged from 60.6% - 120.1%, with relative standard deviation (n = 6) less than 25%. The limit of quantitation for plant toxins ranged from 1 - 20 μg/kg. The developed screening method was used in determination of honey, herbal beverage and honey flavored tea beverage samples. The results showed that berberine was detected in one honey with 1 μg/kg and caffeine was present in some beverages with the concentration from 200 and 5500 μg/kg. This method could meet the requirement for rapid screening of plant toxins in honey and herbal beverage. It can be used for the quality control of honey and herbal beverage in enterprises or quality inspection departments. It also can be used in the rapid screening of food poisoning.
基金Supported by the National Natural Science Foundation of China(11528102)the National Institutes of Health(U01CA209414)
文摘Many modern biomedical studies have yielded survival data with high-throughput predictors.The goals of scientific research often lie in identifying predictive biomarkers,understanding biological mechanisms and making accurate and precise predictions.Variable screening is a crucial first step in achieving these goals.This work conducts a selective review of feature screening procedures for survival data with ultrahigh dimensional covariates.We present the main methodologies,along with the key conditions that ensure sure screening properties.The practical utility of these methods is examined via extensive simulations.We conclude the review with some future opportunities in this field.