原特提斯的消減極性:西昆侖128公里巖體的啟示

The Yirba (128 km) pluton is an early Paleozoic dioritic intrusion of western Kunlun orogenic belt, northwest China as an important element when reconstructing the evolution history of this belt. Due to the scarcity of field data and methodological difference in studying this pluton, however, no consensus for its age, source and tectonic setting has been adopted. In this paper, we present new geochronological and geochemical data for the Yirba pluton, aiming to better understand its age, source, and hence the early Paleozoic tectonic evolutionary history of western Kunlun. U-Pb data by single grain zircon analyses suggest that the Yirba pluton was emplaced 471 ± 5 Ma ago and contains ca. 490 Ma zircon grains inherited from source, or captured in the magma chamber. The pluton is enriched in Al 2 O 3 (15.7% ∼ 18.4%), Sr (470 ∼ 864 μg/g) and other LILEs (large ion lithosphile elements), but relatively depleted in HFSE (high field strength elements and HREE), with LREE-enriched patterns and low to medium europium anomalies (δEu = ∼ 0.7), showing typical characteristics of I-type, volcanic arc granitoids. Although its relatively high Al 2 O 3, Sr and low MgO contents make it resemble adakite, its relatively high Yb (1.92 ∼ 2.88 μg/g), Y (19.4 ∼ 34.0 μg/g) contents, low Sr/Y (24.2 ∼ 37.0) , Zr/Sm (7.3 ∼ 21) and relatively high initial Sr isotope ratios (0.7075 ∼ 0.7091) do not support a subducting slab origin. Its Nd model ages (1.06 ∼ 1.35 Ga) indicate a juvenile source, while its O isotope compositions (+5.7‰ ∼ + 7.4‰) and Sr-O isotope relationship preclude significant involvement of sialic materials. The major, trace, REE and Nd-Sr-O isotope compositions strongly suggest that the Yirba pluton was formed by partial melting of mafic lower crust in a southward growing, active continental margin environment. The existence of volcanic arc granitoids in the south margin of the North Kunlun terrane suggests that the subduction polarity of the Proto-Tethys was northward.128公里巖體是西昆侖造山帶中一個早古生代的花崗閃長巖體,長期以來一直是研究西昆侖構造演化的重要參考依據。然而由于區域地質資料的不足和研究手段的不同,對該巖體的形成年代、源區性質以及構造背景等方面還存在著不同的認識。本文試圖通過地質年代學和地球化學方面的研究,明確128公里巖體的成巖時代和構造背景,進而制約西昆侖的早古生代構造演化。單顆粒鋯石的U-Pb定年結果表明128公里巖體形成于471±5 Ma并含有可能形成于早期巖漿房或繼承自源區的490 Ma左右的鋯石。128公里巖體富Al_2O_3(15.7％～18.4％),Sr(470～864μg/g)和大離子親石元素但相對虧損 高場強元素,相對富集輕稀土且具有低到中等的負銪異常(δEu=～0.7),顯示出典型的Ⅰ型弧花崗巖特征。盡管其富集Al_2O_3、Sr、相對低的MgO含量和Y/Yb比值使其非常類似于埃達克巖,但其相對高的Yb(1.92～2.88μg/g)、Y(19.4～34.0μg/g)含量,低的Sr/Y(24.2～37.0)和Zr/Sm(7.3～21)比值以及相對高的初始Sr同位素組成(0.7075～0.7091)排除了消減板塊在石榴石穩定區發生部分熔融的可能性。低的氧同位素组成( + 5.7％～7.4％) 以及Sr-O 同位素关系表明该岩体并非形成于地慢来源的岩泉与变质围岩间的同化混染。高的稀土含量、明显的稀土分馏以及相对高的Sr 同位素组成表明12 8 公里岩体不大可能形成于受陆源物质影响较小的大洋岛弧, 而更可能形成于活动大陆边缘环境中基性地壳物质的部分熔融。北昆仑地体的南缘存在火山弧型花岗岩的事实表明, 原特提斯的消减方向应当是向北的。published_or_final_versio

Novel critical point drying (CPD) based preparation and transmission electron microscopy (TEM) imaging of protein specific molecularly imprinted polymers (HydroMIPs)

We report the transmission electron microscopy (TEM) imaging of a hydrogel-based molecularly imprinted polymer (HydroMIP) specific to the template molecule bovine haemoglobin (BHb). A novel critical point drying based sample preparation technique was employed to prepare the molecularly imprinted polymer (MIP) samples in a manner that would facilitate the use of TEM to image the imprinted cavities, and provide an appropriate degree of both magnification and resolution to image polymer architecture in the <10 nm range. For the first time, polymer structure has been detailed that clearly displays molecularly imprinted cavities, ranging from 5-50 nm in size, that correlate (in terms of size) with the protein molecule employed as the imprinting template. The modified critical point drying sample preparation technique used may potentially play a key role in the imaging of all molecularly imprinted polymers, particularly those prepared in the aqueous phase

A pore-expanded supramolecular organic framework and its enrichment of photosensitizers and catalysts for visible-light-induced hydrogen production

A pore-expanded three-dimensional supramolecular organic framework SOF-bpb, with a previously unattained aperture size of 3.6 nm, has been constructed in water from the co-Assembly of cucurbit[8]uril (CB[8]) and a tetraphenylmethane-cored 1,4-bis(pyridin-4-yl)-benzene-Appended building block M1. The periodicity of SOF-bpb in water and in the solid state has been confirmed using synchrotron X-ray scattering and diffraction experiments. SOF-bpb can adsorb anionic and neutral Ru complex photosensitizers and anionic Wells-Dawson-Type and Keggin-Type polyoxometalates (POMs). The adsorption leads to an important enrichment effect, which remarkably increases the catalytic efficiency of the Ru complex-POM systems for visible light-induced reduction of protons to produce H . The expanded aperture of SOF-bpb also facilitates light absorption of the adsorbed Ru complex photosensitizers and electron transfer between excited complexes and the POM catalysts, leading to enhanced photocatalytic activities as compared with the prototypical SOF that has an aperture size of 2.1 nm. 2+ 2+ 2+

Novel hydrogel obtained by chitosan and dextrin-VA co-polymerization

A novel hydrogel was obtained by reticulation of chitosan with dextrin enzymatically linked to vinyl acrylate (dextrin-VA), without cross-linking agents. The hydrogel had a solid-like behaviour with G′ (storage modulus) >> G″ (loss modulus). Glucose diffusion coefficients of 3.9 × 10−6 ± 1.3 × 10−6 cm2/s and 2.9 × 10−6 ± 0.5 × 10−6 cm2/s were obtained for different substitution degrees of the dextrin-VA (20% and 70% respectively). SEM observation revealed a porous structure, with pores ranging from 50 µm to 150 µm

Characterisation of the bacterial and fungal communities associated with different lesion sizes of Dark Spot Syndrome occurring in the Coral Stephanocoenia intersepta

The number and prevalence of coral diseases/syndromes are increasing worldwide. Dark Spot Syndrome (DSS) afflicts numerous coral species and is widespread throughout the Caribbean, yet there are no known causal agents. In this study we aimed to characterise the microbial communities (bacteria and fungi) associated with DSS lesions affecting the coral Stephanocoenia intersepta using nonculture molecular techniques. Bacterial diversity of healthy tissues (H), those in advance of the lesion interface (apparently healthy AH), and three sizes of disease lesions (small, medium, and large) varied significantly (ANOSIM R = 0.052 p,0.001), apart from the medium and large lesions, which were similar in their community profile. Four bacteria fitted into the pattern expected from potential pathogens; namely absent from H, increasing in abundance within AH, and dominant in the lesions themselves. These included ribotypes related to Corynebacterium (KC190237), Acinetobacter (KC190251), Parvularculaceae (KC19027), and Oscillatoria (KC190271). Furthermore, two Vibrio species, a genus including many proposed coral pathogens, dominated the disease lesion and were absent from H and AH tissues, making them candidates as potential pathogens for DSS. In contrast, other members of bacteria from the same genus, such as V. harveyii were present throughout all sample types, supporting previous studies where potential coral pathogens exist in healthy tissues. Fungal diversity varied significantly as well, however the main difference between diseased and healthy tissues was the dominance of one ribotype, closely related to the plant pathogen, Rhytisma acerinum, a known causal agent of tar spot on tree leaves. As the corals’ symbiotic algae have been shown to turn to a darker pigmented state in DSS (giving rise to the syndromes name), the two most likely pathogens are R. acerinum and the bacterium Oscillatoria, which has been identified as the causal agent of the colouration in Black Band Disease, another widespread coral disease

Insulators and imprinting from flies to mammals

The nuclear factor CTCF has been shown to be necessary for the maintenance of genetic imprinting at the mammalian H19/Igf2 locus. MacDonald and colleagues now report in BMC Biology that the mechanisms responsible for maintaining the imprinted state in Drosophila may be evolutionarily conserved and that CTCF may also play a critical role in this process

Gas accretion as the origin of chemical abundance gradients in distant galaxies

It has recently been suggested that galaxies in the early Universe can grow through the accretion of cold gas, and that this may have been the main driver of star formation and stellar mass growth. Because the cold gas is essentially primordial, it has a very low abundance of elements heavier than helium (metallicity). As it is funneled to the centre of a galaxy, it will lead the central gas having an overall lower metallicity than gas further from the centre, because the gas further out has been enriched by supernovae and stellar winds, and not diluted by the primordial gas. Here we report chemical abundances across three rotationally-supported star-forming galaxies at z~3, only 2 Gyr after the Big Bang. We find an 'inverse' gradient, with the central, star forming regions having a lower metallicity than less active ones, opposite to what is seen in local galaxies. We conclude that the central gas has been diluted by the accretion of primordial gas, as predicted by 'cold flow' models.Comment: To Appear in Nature Oct 14, 2010; Supplementary Information included her

Effects of Dapagliflozin in Chronic Kidney Disease Across the Spectrum of Age and by Sex

Background: The sodium-glucose cotransporter type 2 inhibitor dapagliflozin reduces the risk of progressive kidney disease and cardiovascular events in patients with chronic kidney disease, with and without type 2 diabetes. Whether its effects are uniform across the spectrum of age and among men and women is unknown. // Objective: We performed a pre-specified analysis in DAPA-CKD to evaluate efficacy and safety of dapagliflozin according to baseline age and sex. // Design: Prospective randomized placebo-controlled trial. // Participants: A total of 4304 adults with chronic kidney disease (estimated glomerular filtration rate (eGFR) 25–75 mL/min/1.73 m2; urinary albumin-to-creatinine ratio 200–5000 mg/g) with and without type 2 diabetes. // Intervention: Dapagliflozin 10 mg versus placebo once daily. // Main Measures: Primary endpoint was a composite of ≥ 50% sustained eGFR decline, end-stage kidney disease, and kidney or cardiovascular death. Secondary endpoints included kidney composite endpoint (same as primary composite endpoint but without cardiovascular death), cardiovascular composite endpoint (hospitalized heart failure or cardiovascular death), and all-cause mortality. // Key Results: Median follow-up was 2.4 years. Absolute risks of cardiovascular composite endpoint and all-cause mortality were higher in older patients. Absolute risk of kidney composite endpoint was highest in patients < 50 years (10.7 and 6.2 per 100 patient-years in the placebo and dapagliflozin groups, respectively) and lowest in patients ≥ 80 years (3.0 and 1.2 per 100 patient-years in the placebo and dapagliflozin groups, respectively). There was no evidence of heterogeneity of the effects of dapagliflozin on the primary or secondary endpoints based on age or sex. Neither age nor sex modified the effects of dapagliflozin on total or chronic eGFR slope. // Conclusions: Dapagliflozin reduced the risks of mortality, cardiovascular events, and CKD progression in older patients, including in septuagenarians and octogenarians who comprised 25% of participants. Ageism and/or therapeutic nihilism should not discourage the use of dapagliflozin in older women and men who are likely to experience considerable benefit. // Trial Registry: clinicaltrials.gov // NIH Trial Registry Number: NCT0303615

Paleogenome reveals genetic contribution of extinct giant panda to extant populations

Historically, the giant panda was widely distributed from northern China to southwestern Asia. As a result of range contraction and fragmentation, extant individuals are currently restricted to fragmented mountain ranges on the eastern margin of the Qinghai-Tibet plateau, where they are distributed among three major population clusters. However, little is known about the genetic consequences of this dramatic range contraction. For example, were regions where giant pandas previously existed occupied by ancestors of present-day populations, or were these regions occupied by genetically distinct populations that are now extinct? If so, is there any contribution of these extinct populations to the genomes of giant pandas living today? To investigate these questions, we sequenced the nuclear genome of an ∼5,000-year-old giant panda from Jiangdongshan, Tengchong County in Yunnan Province, China. We find that this individual represents a genetically distinct population that diverged prior to the diversification of modern giant panda populations. We find evidence of differential admixture with this ancient population among modern individuals originating from different populations as well as within the same population. We also find evidence for directional gene flow, which transferred alleles from the ancient population into the modern giant panda lineages. A variable proportion of the genomes of extant individuals is therefore likely derived from the ancient population represented by our sequenced individual. Although extant giant panda populations retain reasonable genetic diversity, our results suggest that this represents only part of the genetic diversity this species harbored prior to its recent range contractions