背景：以前的血管内超声（intravascular ultrasound，IVUS）试验证实，他汀治疗可减缓或阻止动脉粥样硬化的进展，但是迄今尚无应用动脉粥样斑块体积百分比（percent atheroma volume，PAV）证实粥样硬化消退的确切证据。PAV是最严格...背景：以前的血管内超声（intravascular ultrasound，IVUS）试验证实，他汀治疗可减缓或阻止动脉粥样硬化的进展，但是迄今尚无应用动脉粥样斑块体积百分比（percent atheroma volume，PAV）证实粥样硬化消退的确切证据。PAV是最严格的评价病变进展和消退的IVUS测量指标。
目标：评价极高强度他汀治疗是否能逆转IVUS确定的冠状动脉粥样硬化。
设计和地点：于美国、加拿大、欧洲和澳大利亚53个社区和3级保健中心进行前瞻性开标盲法终点试验（A Study to Evaluate the Effect of Rosuvastatin on Intravascular Ultrasound-Derived Coronary Atheroma Burden，ASTEROID）。应用马达驱动回撤IVUS评价基线和治疗24个月时冠状动脉粥样斑块负荷。每对基线和随访IVUS测量结果均进行盲法分析。
病例：从2002年11月到2003年10月，507例患者有基线IVUS检查结果，并接受至少1个剂量的研究药物。在24个月后，349例患者具有可用于评估的系列IVUS检查结果。
干预：所有患者均接受瑞舒伐他汀40ms／d强化治疗。
主要观测指标：预先设定了两个一级疗效指标：PAV变化和基线最严重病变10min节段动脉粥样斑块体积变化。二级疗效指标为整个动脉标准化总斑块体积的变化。结果：平均（SD）LDL—C水平由基线时的130．4（34．3）ms／dL降至60．8（20．0）ms／扎，平均下降了53．2％（P〈0．001）。平均（SD）HDL-C水平从基线时的43．1（11．1）ms／dL升至49．0（12．6）ms／dL，平均增加了14．7％（P〈0．001）。整个血管PAV平均（SD）变化为-0．98％（3．15％），中位数为-0．79％（97．5％CI，-1．21％～-0．53％）（与基线比较，P〈0．001）。最严重病变10min节段斑块体积平均（SD）变化为-6．1（10．1）mm^3，中位数为-5．6mm^3（97．5％CI，-6．8～-4．0mm^3）（与基线比较，P〈0．001）。总斑块体积变化中位数降低了6．8％，�展开更多
Dear Editor, Recently, engineered endonucleases, such as Zinc-Finger Nucleases （ZFNs） （Carroll, 2011）, Transcription Activator-Like Effector Nucleases （TALENs） （Mahfouz et al., 2011; Li et al., 2012）, and Clu...Dear Editor, Recently, engineered endonucleases, such as Zinc-Finger Nucleases （ZFNs） （Carroll, 2011）, Transcription Activator-Like Effector Nucleases （TALENs） （Mahfouz et al., 2011; Li et al., 2012）, and Clustered Regularly Interspaced Short Palindromic Repeats （CRISPR）-associated （Cas） systems （Cong et al., 2013） have been successfully used for gene editing in a variety of species. These systems generate double-strand breaks （DSBs） at target loci to drive site-specific DNA sequence modifica- tions. The modifications include sequence insertion and deletion and other mutations in the host genomes via the error-prone non-homologous end joining （NHEJ） pathway or sequence correction or replacement through the error-free homologous recombination （HR） pathway （Symington and Gautier, 2011）. Here, we show that the CRISPR-Cas system can be applied to generate targeted gene mutations and gene corrections in plants, and the system can also be readily engi- neered to achieve deletion of large DNA fragments and for multiplex gene editing in plants.展开更多
Lawrence E. Murr is Mr.J Mrs. Macintosh Murehison Professor and Chairman of the Department of Metallurgical and Materials Engineering and Ph.D. Program Director in the Materials Research Technology Institute at The Un...Lawrence E. Murr is Mr.J Mrs. Macintosh Murehison Professor and Chairman of the Department of Metallurgical and Materials Engineering and Ph.D. Program Director in the Materials Research Technology Institute at The University of Texas at El Paso. Dr. Murr received his B.Sc. in physical science from Albright College, and his B.S.E.E. in electronics, his M.S. in engineering mechanics, and his Ph.D. in solidstate science, all from the Pennsylvania State University. Dr. Murr has published 20 books, over 750 scientific and technical articles in a wide range of research areas in materials science and engineering, environmental science and engineering, manufacturing science and engineering （especially rapid prototype/layered manufacturing）,展开更多
The disinfection of drinking water is an important public health service that generates high quality, safe and palatable tap water. The disinfection of drinking water to reduce waterborne disease was an outstanding pu...The disinfection of drinking water is an important public health service that generates high quality, safe and palatable tap water. The disinfection of drinking water to reduce waterborne disease was an outstanding public health achievement of the 20 th century.An unintended consequence is the reaction of disinfectants with natural organic matter,anthropogenic contaminants and bromide/iodide to form disinfection by-products（DBPs）.A large number of DBPs are cytotoxic, neurotoxic, mutagenic, genotoxic, carcinogenic and teratogenic. Epidemiological studies demonstrated low but significant associations between disinfected drinking water and adverse health effects. The distribution of DBPs in disinfected waters has been well defined by advances in high precision analytical chemistry. Progress in the analytical biology and toxicology of DBPs has been forthcoming.The objective of this review was to provide a detailed presentation of the methodology for the quantitative, comparative analyses on the induction of cytotoxicity and genotoxicity of103 DBPs using an identical analytical biological platform and endpoints. A single Chinese hamster ovary cell line was employed in the assays. The data presented are derived from papers published in the literature as well as additional new data and represent the largest direct quantitative comparison on the toxic potency of both regulated and emerging DBPs.These data may form the foundation of novel research to define the major forcing agents of DBP-mediated toxicity in disinfected water and may play an important role in achieving the goal of making safe drinking water better.展开更多
Carotenoids are indispensable to plants and critical in human diets. Plastids are the organelles for carotenoid biosynthesis and storage in plant cells. They exist in various types, which include proplastids, etioplas...Carotenoids are indispensable to plants and critical in human diets. Plastids are the organelles for carotenoid biosynthesis and storage in plant cells. They exist in various types, which include proplastids, etioplasts, chloroplasts, amyloplasts, and chromoplasts. These plastids have dramatic differences in their capacity to synthesize and sequester carotenoids. Clearly, plastids play a central role in governing carotenogenic activity, carotenoid stability, and pigment diversity. Understanding of carotenoid metabolism and accumulation in various plastids expands our view on the multifaceted regulation of carotenogenesis and facilitates our efforts toward developing nutrient-enriched food crops. In this review, we provide a comprehensive overview of the impact of various types of plastids on carotenoid biosynthesis and accumulation, and discuss recent advances in our understanding of the regulatory control of carotenogenesis and metabolic engineering of carotenoids in light of plastid types in plants.展开更多
A four-year field experiment was conducted to investigate the effect of subsoiling depth on root morphology, nitrogen(N), phosphorus(P), and potassium(K) uptake, and grain yield of spring maize. The results indicated ...A four-year field experiment was conducted to investigate the effect of subsoiling depth on root morphology, nitrogen(N), phosphorus(P), and potassium(K) uptake, and grain yield of spring maize. The results indicated that subsoil tillage promoted root development,increased nutrient accumulation, and increased yield. Compared with conventional soil management(CK), root length, root surface area, and root dry weight at 0–80 cm soil depth under subsoil tillage to 30 cm(T1) and subsoil tillage to 50 cm(T2) were significantly increased, especially the proportions of roots in deeper soil. Root length, surface area, and dry weight differed significantly among three treatments in the order of T2 > T1 > CK at the12-leaf and early filling stages. The range of variation of root diameter in different soil layers in T2 treatment was the smallest, suggesting that roots were more likely to grow downwards with deeper subsoil tillage in soil. The accumulation of N, P, and K in subsoil tillage treatment was significantly increased, but the proportions of kernel and straw were different. In a comparison of T1 with T2, the grain accumulated more N and P, while K accumulation in kernel and straw varied in different years. Grain yield and biomass were increased by 12.8% and 14.6% on average in subsoil tillage treatments compared to conventional soil treatment. Although no significant differences between different subsoil tillage depths were observed for nutrient accumulation and grain yield, lodging resistance of plants was significantly improved in subsoil tillage to 50 cm, a characteristic that favors a high and stable yield under extreme environments.展开更多
BACKGROUND: Intracerebral hemorrhage is the least treatable form of stroke and is associated with high mortality.Among patients who undergo computed tomograph y (CT) within three hours after the onset of intracerebral...BACKGROUND: Intracerebral hemorrhage is the least treatable form of stroke and is associated with high mortality.Among patients who undergo computed tomograph y (CT) within three hours after the onset of intracerebral hemorrhage, one third have an increase in the volume of the hematoma related to subsequent bleeding. We sought to determine whether recombinant activated factor VII (rFVIIa) can red uce hematoma growth after intracerebral hemorrhage. METHODS: We randomly assigne d 399 patients with intracerebral hemorrhage diagnosed by CT within three hours after onset to receive placebo (96 patients) or 40 μg of rFVIIa per kilogram of body weight (108 patients), 80 μg per kilogram (92 patients), or 160 μg per k ilogram (103 patients) within one hour after the baseline scan. The primary outc ome measure was the percent change in the volume of the intracerebral hemorrhage at 24 hours. Clinical outcomes were assessed at 90 days. RESULTS: Hematoma volu me increased more in the placebo group than in the rFVIIa groups. The mean incre ase was 29 percent in the placebo group, as compared with 16 percent, 14 percent , and 11 percent in the groups given 40 μg, 80 μg, and 160 μg of rFVIIa per k ilogram, respectively (P=0.01 for the comparison of the three rFVIIa groups with the placebo group). Growth in the volume of intracerebral hemorrhage was reduce d by 3.3 ml, 4.5 ml, and 5.8 ml in the three treatment groups, as compared with that in the placebo group (P=0.01). Sixty-nine percent of placebo-treated pati ents died or were severely disabled (as defined by a modified Rankin Scale score of 4 to 6), as compared with 55 percent, 49 percent, and 54 percent of the pati ents who were given 40, 80, and 160 μg of rFVIIa, respectively (P=0.004 for the comparison of the three rFVIIa groups with the placebo group). Mortality at 90 days was 29 percent for patients who received placebo, as compared with 18 perce nt in the three rFVIIa groups combined (P=0.02). Serious thromboembolic adverse events, mainly myocardial or cerebral i展开更多
The Cucurbita genus contains several economically important species in the Cucurbitaceae family. Here, we report high-quality genome sequences of C. maxima and C. moschata and provide evidence supporting an allotetrap...The Cucurbita genus contains several economically important species in the Cucurbitaceae family. Here, we report high-quality genome sequences of C. maxima and C. moschata and provide evidence supporting an allotetraploidization event in Cucurbita. We are able to partition the genome into two homoeologous subgenomes based on different genetic distances to melon, cucumber, and watermelon in the Benincaseae tribe. We estimate that the two diploid progenitors successively diverged from Benincaseae around 31 and 26 million years ago （Mya）, respectively, and the allotetraploidization happened at some point between 26 Mya and 3 Mya, the estimated date when C. maxima and C. moschata diverged. The subgenomes have largely maintained the chromosome structures of their diploid progenitors. Such long-term karyotype stability after polyploidization has not been commonly observed in plant polyploids. The two subgenomes have retained similar numbers of genes, and neither subgenome is globally dominant in gene expression. Allele-specific expression analysis in the C. maxima ×C. moschata interspecific F1 hybrid and their two parents indicates the predominance of trans-regulatory effects underlying expression divergence of the parents, and detects transgressive gene expression changes in the hybrid correlated with heterosis in important agronomic traits. Our study provides insights into polyploid genome evolution and valuable resources for genetic improvement of cucurbit crops.展开更多
The role of Bone Tissue Engineering in the field of Regenerative Medicine has been the topic of substantial research over the past two decades. Technological advances have improved orthopaedic implants and surgical te...The role of Bone Tissue Engineering in the field of Regenerative Medicine has been the topic of substantial research over the past two decades. Technological advances have improved orthopaedic implants and surgical techniques for bone reconstruction. However, improvements in surgical techniques to reconstruct bone have been limited by the paucity of autologous materials available and donor site morbidity. Recent advances in the development of biomaterials have provided attractive alternatives to bone grafting expanding the surgical options for restoring the form and function of injured bone. Specifically, novel bioactive （second generation） biomaterials have been developed that are characterised by controlled action and reaction to the host tissue environment, whilst exhibiting controlled chemical breakdown and resorption with an ultimate replacement by regenerating tissue. Future generations of biomaterials （third generation） are designed to be not only osteo- conductive but also osteoinductive, i.e. to stimulate regeneration of host tissues by combining tissue engineer- ing and in situ tissue regeneration methods with a focus on novel applications. These techniques will lead to novel possibilities for tissue regeneration and repair. At present, tissue engineered constructs that may find future use as bone grafts for complex skeletal defects, whether from post-traumatic, degenerative, neoplastic or congenital/developmental ＂origin＂ require osseous reconstruction to ensure structural and functional integrity. Engineering functional bone using combinations of cells, scaffolds and bioactive factors is a promising strategy and a particular feature for future development in the area of hybrid materials which are able to exhibit suitable biomimetic and mechanical properties. This review will discuss the state of the art in this field and what we can expect from future generations of bone regeneration concepts.展开更多
Background The incidence of spinal injury with spinal cord contusion is high in developed countries and is now growing in China. Furthermore, spinal cord injury happens mostly in young people who have a long life expe...Background The incidence of spinal injury with spinal cord contusion is high in developed countries and is now growing in China. Furthermore, spinal cord injury happens mostly in young people who have a long life expectance. A large number of patients thus are wheelchair bound for the rest of their lives. Therefore, spinal cord injury has aroused great concern worldwide. Despite great efforts, recovery from spinal cord injury remains unsatisfactory. Based on the pathology of spinal cord contusion, an idea of early neurosurgical intervention has been formulated in this study. Methods A total of 30 patients with ＂complete＂ spinal cord injury or classified as American Spinal Injury Association （ASIA）-A were studied. Orthopedic treatment of the injured vertebra（e）, internal fixation of the vertebral column, and bilateral laminectomy for epidural decompression were followed directly by neurosurgical management, including separation of the arachnoid adhesion to restore cerebrospinal fluid flow and debridement of the spinal cord necrotic tissue with concomitant intramedullary decompression. Rehabilitation started 17 days after the operation. The final outcome was evaluated after 3 months of rehabilitation. Pearson chi-square analysis was used for statistical analysis. Results All the patients recovered some ability to walk. The least recovered patients were able to walk with a wheeled weight support and help in stabilizing the weight bearing knee joint （12 cases, 40%）. Thirteen patients （43%） were able to walk with a pair of crutches, a stick or without any support. The timing of the operation after injury was important. An optimal operation time window was identified at 4-14 days after injury. Conclusions Early neurosurgical intervention of spinal cord contusion followed by rehabilitation can significantly improve the locomotion of the patients. It is a new idea of a therapeutic approach for spinal cord contusion and has been proven to be very successful.展开更多
Electrochemical potassium ion intercalation into two-dimensional layered MoS2 was studied for the first time for potential applications in the anode in potassium-based batteries. X-ray diffraction analysis indicated t...Electrochemical potassium ion intercalation into two-dimensional layered MoS2 was studied for the first time for potential applications in the anode in potassium-based batteries. X-ray diffraction analysis indicated that an intercalated potassium compound, hexagonal K0.4MoS2, formed during the intercalation process. Despite the size of K^＋, MoS2 was a long-life host for repetitive potassium ion intercalation and de-intercalation with a capacity retention of 97.5% after 200 cycles. The diffusion coefficient of the K^＋ ions in KxMoS2 was calculated based on the Randles-Sevcik equation. A higher K^＋ intercalation ratio not only encountered a much slower K^＋ diffusion rate in MoS2, but also induced MoS2 reduction. This study shows that metal dichalcogenides are promising potassium anode materials for emerging K-ion, K-O2, and K-S batteries.展开更多
Background -Pretreatment is not the most common strategy practiced for clopidogrel administration in elective coronary stenting. Moreover, limited information is available on the antiplatelet pharmacodynamics of a 300...Background -Pretreatment is not the most common strategy practiced for clopidogrel administration in elective coronary stenting. Moreover, limited information is available on the antiplatelet pharmacodynamics of a 300-mg versus a 600-mg clopidogrel loading dose, and the comparative effect of eptifibatide with these regimens is unknown. Methods and Results -Patients undergoing elective stenting (n=120) were enrolled in a 2X2 factorial study(300 mg clopidogrel with or without eptifibatide; 600 mg clopidogrel with or without eptifibatide)(Clopidogrel Loading With Eptifibatide to Arrest the Reactivity of Platelets[CLEAR PLATELETS] Study). Clopidogrel was administered immediately after stenting. Aggregometry and flow cytometry were used to assess platelet reactivity. Eptifibatide added a ≥2-fold increase in platelet inhibition to 600 mg clopidogrel alone at 3, 8, and 18 to 24 hours after stenting as measured by 5 μmol/L ADP-induced aggregation(P< 0.001). Without eptifibatide, 600 mg clopidogrel produced better inhibition than 300 mg clopidogrel at all time points(P< 0.001). Glycoprotein IIb/IIIa(GPIIb/IIIa) blockade was associated with lower cardiac marker release. Active GPIIb/IIIa expression was inhibited most in the groups treated with eptifibatide(P< 0.05). Conclusions -In elective stenting without clopidogrel pretreatment, use of a GPIIb/IIIa inhibitor produces superior platelet inhibition and lower myocardial necrosis compared with high-dose(600 mg) or standard-dose(300 mg) clopidogrel loading alone. In the absence of a GPIIb/IIIa inhibitor, 600 mg clopidogrel provides better platelet inhibition than the standard 300-mg dose. These results require confirmation in a large-scale clinical trial.展开更多
BACKGROUND: Fatty liver disease (FLD) is increasingly recognized as one of the most common chronic liver diseases in China. This study aimed to investigate the prevalence and risk factors of FLD in Chengdu, Southwest ...BACKGROUND: Fatty liver disease (FLD) is increasingly recognized as one of the most common chronic liver diseases in China. This study aimed to investigate the prevalence and risk factors of FLD in Chengdu, Southwest China, and to provide a relevant basis for the prevention and intervention of FLD. METHODS: Altogether 9094 subjects (4721 men and 4373 women) of over 18 years old who had received a medical checkup in the West China Hospital of Sichuan University between January and December 2007 were evaluated for FLD. FLD was diagnosed by ultrasonography. Body mass index (BMI), height, body weight, blood pressure, fasting plasma glucose (FPG), triglycerides (TG), total cholesterol (TCh), alanine aminotransferase (ALT), hepatitis B surface antigen (HBsAg), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were measured using routine laboratory methods. RESULTS: The overall prevalence of FLD was 12.5%, which was more than 3-fold higher in males than in females 2 (18.9% vs. 5.7%, chi(2) =359.624, P<0.001). The prevalence increased with age in females and males of less than 50 years. The prevalence of alcoholic, suspected alcoholic, and non-alcoholic FLD was 2.6%, 3.6%, and 6.3%, respectively. Multiple logistic regression analyses showed that 10 factors (male sex, age, BMI, FPG, hypertension, TG, TCh, HDL-C, LDL-C, and ALT abnormalities) were closely related to FLD. In heavy drinkers, obesity increased the risk of FLD by 23.78-fold (95% CI, 10.22-55.33), but heavy drinking was only associated with a 2-fold (95% CI, 1.50-2.66) increased risk in obese subjects. CONCLUSIONS: The prevalence of FLD among a health-checkup population in Chengdu, Southwest China was lower than the published for other areas of China. FLD in Chengdu adults was found to be closely associated with sex, age, BMI, and other metabolic syndrome features.展开更多
AIM:To evaluate the detection and differentiation ability of contrast-enhanced intraoperative ultrasonography(CE-IOUS) in hepatocellular carcinoma(HCC) operations.METHODS:Clinical data of 50 HCC patients were retrospe...AIM:To evaluate the detection and differentiation ability of contrast-enhanced intraoperative ultrasonography(CE-IOUS) in hepatocellular carcinoma(HCC) operations.METHODS:Clinical data of 50 HCC patients were retrospective analyzed.The sensitivity,specificity,false negative and false positive rates of contrast enhanced magnetic resonance imaging(CE-MRI),IOUS and CEIOUS were calculated and compared.Surgical strategy changes due to CE-IOUS were analyzed.RESULTS:Lesions detected by CE-MRI,IOUS and CEIOUS were 60,97 and 85 respectively.The sensitivity,specificity,false negative rate,false positive rate of CEMRI were 98.2%,98.6%,98.6%,60.0%,respectively;for IOUS were 50.0%,90.9%,1.8%,1.4%,respectively;and for CE-IOUS were 1.4%,40.0%,50.0%,9.1%,respectively.The operation strategy of 9(9/50,18.0%) cases was changed according to the results of CE-IOUS.CONCLUSION:Compared with CE-MRI,CE-IOUS performs better in detection and differentiation of small metastasis and regenerative nodules.It plays an important role in the decision-making of HCC operation.展开更多
AIM:To report the incidence of non-small-bowel bleeding pathologies encountered during double-balloon enteroscopy (DBE) procedures and to analyse their significance.METHODS: A retrospective study of a prospective DBE ...AIM:To report the incidence of non-small-bowel bleeding pathologies encountered during double-balloon enteroscopy (DBE) procedures and to analyse their significance.METHODS: A retrospective study of a prospective DBE database conducted in a tertiary-referral center was conducted. A total of 179 patients with obscure gastrointestinal bleeding (OGIB) referred for DBE from June 2004 to November 2008 were analysed looking for the incidence of non-small-bowel lesions (NSBLs; all and newly diagnosed) encountered during DBE.RESULTS: There were 228 (150 antegrade and 78 retrograde) DBE procedures performed in 179 patients. The mean number of DBE procedures was 1.27 per patient. The mean age (SD) of the patients was 62 ± 16 years old. There were 94 females (52.5%). The positive yield for a bleeding lesion was 65.9%. Of the 179 patients, 44 (24.6%) had NSBLs (19 of them had dual pathology with small-bowel lesions and NSBLs); 27 (15.1%) had lesions not detected by previous endoscopies. The most common type of missed lesions were vascular lesions.CONCLUSION: A significant proportion of patients (24.6%) had lesions within reach of conventional endoscopy. Careful repeat examination with gastroscopy and colonoscopy might be required.展开更多
Purpose:Mo ve recognition in scientific abstracts is an NLP task of classifying sentences of the abstracts into different types of language units.To improve the performance of move recognition in scientific abstracts,...Purpose:Mo ve recognition in scientific abstracts is an NLP task of classifying sentences of the abstracts into different types of language units.To improve the performance of move recognition in scientific abstracts,a novel model of move recognition is proposed that outperforms the BERT-based method.Design/methodology/approach:Prevalent models based on BERT for sentence classification often classify sentences without considering the context of the sentences.In this paper,inspired by the BERT masked language model(MLM),we propose a novel model called the masked sentence model that integrates the content and contextual information of the sentences in move recognition.Experiments are conducted on the benchmark dataset PubMed 20K RCT in three steps.Then,we compare our model with HSLN-RNN,BERT-based and SciBERT using the same dataset.Findings:Compared with the BERT-based and SciBERT models,the F1 score of our model outperforms them by 4.96%and 4.34%,respectively,which shows the feasibility and effectiveness of the novel model and the result of our model comes closest to the state-of-theart results of HSLN-RNN at present.Research limitations:The sequential features of move labels are not considered,which might be one of the reasons why HSLN-RNN has better performance.Our model is restricted to dealing with biomedical English literature because we use a dataset from PubMed,which is a typical biomedical database,to fine-tune our model.Practical implications:The proposed model is better and simpler in identifying move structures in scientific abstracts and is worthy of text classification experiments for capturing contextual features of sentences.Originality/value:T he study proposes a masked sentence model based on BERT that considers the contextual features of the sentences in abstracts in a new way.The performance of this classification model is significantly improved by rebuilding the input layer without changing the structure of neural networks.展开更多
The zircon Sensitive High Resolution Ion Microprobe (SHRIMP) results show that granitoid intrusions in Zhaoyc Gold Belt were emplaced at two periods of Mesozoic: Linglong and Luanjiahe types of granitic intrusions wer...The zircon Sensitive High Resolution Ion Microprobe (SHRIMP) results show that granitoid intrusions in Zhaoyc Gold Belt were emplaced at two periods of Mesozoic: Linglong and Luanjiahe types of granitic intrusions were emplaced between 160 Ma and 150 Ma (late Jurassic); Guojialing type of granodioritic intrusions, 130 Ma and 126 Ma (early Cretaceous). All the three types contain at least two major generations of inherited zircons with Precambrian ( >650 Ma) and early Mesozoic ages (200-250 Ma), respectively. The former suggests that these plu-tonic rocks are of crustal origin and that Precambrian basement with component of sialic crust up to 3.4 Ga old ( Middle Archean) exists in the region. The presence of abundant inherited zircons with early Mesozoic age indicates that the Precambrian basement was affected by a major tectono-thermal event, that is the collision of the North and South China blocks, at 250 Ma to 200 Ma. SHRIMP results also indicate that the gold mineralization in the region took place between 126 Ma and 120 Ma.展开更多
Eclogite lenses in marbles from the Dabie-Sulu ultrahigh-pressure （UHP） terrane are deeply subducted meta-sedimentary rocks. Zircons in these rocks have been used to constrain the ages of prograde and UHP metamorphi...Eclogite lenses in marbles from the Dabie-Sulu ultrahigh-pressure （UHP） terrane are deeply subducted meta-sedimentary rocks. Zircons in these rocks have been used to constrain the ages of prograde and UHP metamorphism during subduction, and later retrograde metamorphism during exhumation. Inherited （detrital） and metamorphic zircons were distinguished on the basis of transmitted light microscopy, cathodoluminescence （CL） imaging, trace element contents and mineral inclusions. The distribution of mineral inclusions combined with CL imaging of the metamorphic zircon make it possible to relate zircon zones （domains） to different metamorphic stages. Domain 1 consists of rounded, oblong and spindly cores with dark-luminescent images, and contains quartz eclogite facies mineral inclusion assemblages, indicating formation under high-pressure （HP） metamorphic conditions of T = 571-668℃ and P =1.7-2.02 GPa. Domain 2 always surrounds domain 1 or occurs as rounded and spindly cores with white-luminescent images. It contains coesite eclogite facies mineral inclusion assemblages, indicating formation under UHP metamorphic conditions of T = 782-849℃ and P 〉 5.5 GPa. Domain 3, with gray-luminescent images, always surrounds domain 2 and occurs as the outermost zircon rim. It is characterized by low-pressure mineral inclusion assemblages, which are related to regional amphibolite facies retrograde metamorphism of T = 600- 710℃ and P = 0.7-1.2 GPa. The three metamorphic zircon domains have distinct ages; sample H1 from the Dabie terrane yielded SHRIMP ages of 245 ± 4 Ma for domain 1, 235 ± 3 Ma for domain 2 and 215± 6 Ma for domain 3, whereas sample H2 from the Sulu terrane yielded similar ages of 244 ± 4 Ma, 233 ± 4 Ma and 214 ± 5 Ma for Domains 1, 2 and 3, respectively. The mean ages of these zones suggest that subduction to UHP depths took place over 10-11 Ma and exhumation of the rocks occurred over a period of 19-20 Ma. Thus, subduction from - 55 km to 〉 160 km deep mantle depth took place 展开更多
文摘背景：以前的血管内超声（intravascular ultrasound，IVUS）试验证实，他汀治疗可减缓或阻止动脉粥样硬化的进展，但是迄今尚无应用动脉粥样斑块体积百分比（percent atheroma volume，PAV）证实粥样硬化消退的确切证据。PAV是最严格的评价病变进展和消退的IVUS测量指标。
目标：评价极高强度他汀治疗是否能逆转IVUS确定的冠状动脉粥样硬化。
设计和地点：于美国、加拿大、欧洲和澳大利亚53个社区和3级保健中心进行前瞻性开标盲法终点试验（A Study to Evaluate the Effect of Rosuvastatin on Intravascular Ultrasound-Derived Coronary Atheroma Burden，ASTEROID）。应用马达驱动回撤IVUS评价基线和治疗24个月时冠状动脉粥样斑块负荷。每对基线和随访IVUS测量结果均进行盲法分析。
病例：从2002年11月到2003年10月，507例患者有基线IVUS检查结果，并接受至少1个剂量的研究药物。在24个月后，349例患者具有可用于评估的系列IVUS检查结果。
干预：所有患者均接受瑞舒伐他汀40ms／d强化治疗。
主要观测指标：预先设定了两个一级疗效指标：PAV变化和基线最严重病变10min节段动脉粥样斑块体积变化。二级疗效指标为整个动脉标准化总斑块体积的变化。结果：平均（SD）LDL—C水平由基线时的130．4（34．3）ms／dL降至60．8（20．0）ms／扎，平均下降了53．2％（P〈0．001）。平均（SD）HDL-C水平从基线时的43．1（11．1）ms／dL升至49．0（12．6）ms／dL，平均增加了14．7％（P〈0．001）。整个血管PAV平均（SD）变化为-0．98％（3．15％），中位数为-0．79％（97．5％CI，-1．21％～-0．53％）（与基线比较，P〈0．001）。最严重病变10min节段斑块体积平均（SD）变化为-6．1（10．1）mm^3，中位数为-5．6mm^3（97．5％CI，-6．8～-4．0mm^3）（与基线比较，P〈0．001）。总斑块体积变化中位数降低了6．8％，�
文摘Dear Editor, Recently, engineered endonucleases, such as Zinc-Finger Nucleases （ZFNs） （Carroll, 2011）, Transcription Activator-Like Effector Nucleases （TALENs） （Mahfouz et al., 2011; Li et al., 2012）, and Clustered Regularly Interspaced Short Palindromic Repeats （CRISPR）-associated （Cas） systems （Cong et al., 2013） have been successfully used for gene editing in a variety of species. These systems generate double-strand breaks （DSBs） at target loci to drive site-specific DNA sequence modifica- tions. The modifications include sequence insertion and deletion and other mutations in the host genomes via the error-prone non-homologous end joining （NHEJ） pathway or sequence correction or replacement through the error-free homologous recombination （HR） pathway （Symington and Gautier, 2011）. Here, we show that the CRISPR-Cas system can be applied to generate targeted gene mutations and gene corrections in plants, and the system can also be readily engi- neered to achieve deletion of large DNA fragments and for multiplex gene editing in plants.
基金supported in part by Mr. and Mrs.MacIntosh Murshison Endowments at the University of Texas at El Paso and Lockheed Martin Aeronautics
文摘Lawrence E. Murr is Mr.J Mrs. Macintosh Murehison Professor and Chairman of the Department of Metallurgical and Materials Engineering and Ph.D. Program Director in the Materials Research Technology Institute at The University of Texas at El Paso. Dr. Murr received his B.Sc. in physical science from Albright College, and his B.S.E.E. in electronics, his M.S. in engineering mechanics, and his Ph.D. in solidstate science, all from the Pennsylvania State University. Dr. Murr has published 20 books, over 750 scientific and technical articles in a wide range of research areas in materials science and engineering, environmental science and engineering, manufacturing science and engineering （especially rapid prototype/layered manufacturing）,
文摘The disinfection of drinking water is an important public health service that generates high quality, safe and palatable tap water. The disinfection of drinking water to reduce waterborne disease was an outstanding public health achievement of the 20 th century.An unintended consequence is the reaction of disinfectants with natural organic matter,anthropogenic contaminants and bromide/iodide to form disinfection by-products（DBPs）.A large number of DBPs are cytotoxic, neurotoxic, mutagenic, genotoxic, carcinogenic and teratogenic. Epidemiological studies demonstrated low but significant associations between disinfected drinking water and adverse health effects. The distribution of DBPs in disinfected waters has been well defined by advances in high precision analytical chemistry. Progress in the analytical biology and toxicology of DBPs has been forthcoming.The objective of this review was to provide a detailed presentation of the methodology for the quantitative, comparative analyses on the induction of cytotoxicity and genotoxicity of103 DBPs using an identical analytical biological platform and endpoints. A single Chinese hamster ovary cell line was employed in the assays. The data presented are derived from papers published in the literature as well as additional new data and represent the largest direct quantitative comparison on the toxic potency of both regulated and emerging DBPs.These data may form the foundation of novel research to define the major forcing agents of DBP-mediated toxicity in disinfected water and may play an important role in achieving the goal of making safe drinking water better.
文摘Carotenoids are indispensable to plants and critical in human diets. Plastids are the organelles for carotenoid biosynthesis and storage in plant cells. They exist in various types, which include proplastids, etioplasts, chloroplasts, amyloplasts, and chromoplasts. These plastids have dramatic differences in their capacity to synthesize and sequester carotenoids. Clearly, plastids play a central role in governing carotenogenic activity, carotenoid stability, and pigment diversity. Understanding of carotenoid metabolism and accumulation in various plastids expands our view on the multifaceted regulation of carotenogenesis and facilitates our efforts toward developing nutrient-enriched food crops. In this review, we provide a comprehensive overview of the impact of various types of plastids on carotenoid biosynthesis and accumulation, and discuss recent advances in our understanding of the regulatory control of carotenogenesis and metabolic engineering of carotenoids in light of plastid types in plants.
基金supported by the National Key Technology R&D Program of China(2012BAD04B02,2013BAD07B02,and2011BAD16B10)the Special Fund for Agro-Scientific Research in the Public Interest(201103003 and 201303126-4)the Key Technology R&D Program of Jilin province,China(20126026)
文摘A four-year field experiment was conducted to investigate the effect of subsoiling depth on root morphology, nitrogen(N), phosphorus(P), and potassium(K) uptake, and grain yield of spring maize. The results indicated that subsoil tillage promoted root development,increased nutrient accumulation, and increased yield. Compared with conventional soil management(CK), root length, root surface area, and root dry weight at 0–80 cm soil depth under subsoil tillage to 30 cm(T1) and subsoil tillage to 50 cm(T2) were significantly increased, especially the proportions of roots in deeper soil. Root length, surface area, and dry weight differed significantly among three treatments in the order of T2 > T1 > CK at the12-leaf and early filling stages. The range of variation of root diameter in different soil layers in T2 treatment was the smallest, suggesting that roots were more likely to grow downwards with deeper subsoil tillage in soil. The accumulation of N, P, and K in subsoil tillage treatment was significantly increased, but the proportions of kernel and straw were different. In a comparison of T1 with T2, the grain accumulated more N and P, while K accumulation in kernel and straw varied in different years. Grain yield and biomass were increased by 12.8% and 14.6% on average in subsoil tillage treatments compared to conventional soil treatment. Although no significant differences between different subsoil tillage depths were observed for nutrient accumulation and grain yield, lodging resistance of plants was significantly improved in subsoil tillage to 50 cm, a characteristic that favors a high and stable yield under extreme environments.
文摘BACKGROUND: Intracerebral hemorrhage is the least treatable form of stroke and is associated with high mortality.Among patients who undergo computed tomograph y (CT) within three hours after the onset of intracerebral hemorrhage, one third have an increase in the volume of the hematoma related to subsequent bleeding. We sought to determine whether recombinant activated factor VII (rFVIIa) can red uce hematoma growth after intracerebral hemorrhage. METHODS: We randomly assigne d 399 patients with intracerebral hemorrhage diagnosed by CT within three hours after onset to receive placebo (96 patients) or 40 μg of rFVIIa per kilogram of body weight (108 patients), 80 μg per kilogram (92 patients), or 160 μg per k ilogram (103 patients) within one hour after the baseline scan. The primary outc ome measure was the percent change in the volume of the intracerebral hemorrhage at 24 hours. Clinical outcomes were assessed at 90 days. RESULTS: Hematoma volu me increased more in the placebo group than in the rFVIIa groups. The mean incre ase was 29 percent in the placebo group, as compared with 16 percent, 14 percent , and 11 percent in the groups given 40 μg, 80 μg, and 160 μg of rFVIIa per k ilogram, respectively (P=0.01 for the comparison of the three rFVIIa groups with the placebo group). Growth in the volume of intracerebral hemorrhage was reduce d by 3.3 ml, 4.5 ml, and 5.8 ml in the three treatment groups, as compared with that in the placebo group (P=0.01). Sixty-nine percent of placebo-treated pati ents died or were severely disabled (as defined by a modified Rankin Scale score of 4 to 6), as compared with 55 percent, 49 percent, and 54 percent of the pati ents who were given 40, 80, and 160 μg of rFVIIa, respectively (P=0.004 for the comparison of the three rFVIIa groups with the placebo group). Mortality at 90 days was 29 percent for patients who received placebo, as compared with 18 perce nt in the three rFVIIa groups combined (P=0.02). Serious thromboembolic adverse events, mainly myocardial or cerebral i
文摘The Cucurbita genus contains several economically important species in the Cucurbitaceae family. Here, we report high-quality genome sequences of C. maxima and C. moschata and provide evidence supporting an allotetraploidization event in Cucurbita. We are able to partition the genome into two homoeologous subgenomes based on different genetic distances to melon, cucumber, and watermelon in the Benincaseae tribe. We estimate that the two diploid progenitors successively diverged from Benincaseae around 31 and 26 million years ago （Mya）, respectively, and the allotetraploidization happened at some point between 26 Mya and 3 Mya, the estimated date when C. maxima and C. moschata diverged. The subgenomes have largely maintained the chromosome structures of their diploid progenitors. Such long-term karyotype stability after polyploidization has not been commonly observed in plant polyploids. The two subgenomes have retained similar numbers of genes, and neither subgenome is globally dominant in gene expression. Allele-specific expression analysis in the C. maxima ×C. moschata interspecific F1 hybrid and their two parents indicates the predominance of trans-regulatory effects underlying expression divergence of the parents, and detects transgressive gene expression changes in the hybrid correlated with heterosis in important agronomic traits. Our study provides insights into polyploid genome evolution and valuable resources for genetic improvement of cucurbit crops.
文摘The role of Bone Tissue Engineering in the field of Regenerative Medicine has been the topic of substantial research over the past two decades. Technological advances have improved orthopaedic implants and surgical techniques for bone reconstruction. However, improvements in surgical techniques to reconstruct bone have been limited by the paucity of autologous materials available and donor site morbidity. Recent advances in the development of biomaterials have provided attractive alternatives to bone grafting expanding the surgical options for restoring the form and function of injured bone. Specifically, novel bioactive （second generation） biomaterials have been developed that are characterised by controlled action and reaction to the host tissue environment, whilst exhibiting controlled chemical breakdown and resorption with an ultimate replacement by regenerating tissue. Future generations of biomaterials （third generation） are designed to be not only osteo- conductive but also osteoinductive, i.e. to stimulate regeneration of host tissues by combining tissue engineer- ing and in situ tissue regeneration methods with a focus on novel applications. These techniques will lead to novel possibilities for tissue regeneration and repair. At present, tissue engineered constructs that may find future use as bone grafts for complex skeletal defects, whether from post-traumatic, degenerative, neoplastic or congenital/developmental ＂origin＂ require osseous reconstruction to ensure structural and functional integrity. Engineering functional bone using combinations of cells, scaffolds and bioactive factors is a promising strategy and a particular feature for future development in the area of hybrid materials which are able to exhibit suitable biomimetic and mechanical properties. This review will discuss the state of the art in this field and what we can expect from future generations of bone regeneration concepts.
文摘Background The incidence of spinal injury with spinal cord contusion is high in developed countries and is now growing in China. Furthermore, spinal cord injury happens mostly in young people who have a long life expectance. A large number of patients thus are wheelchair bound for the rest of their lives. Therefore, spinal cord injury has aroused great concern worldwide. Despite great efforts, recovery from spinal cord injury remains unsatisfactory. Based on the pathology of spinal cord contusion, an idea of early neurosurgical intervention has been formulated in this study. Methods A total of 30 patients with ＂complete＂ spinal cord injury or classified as American Spinal Injury Association （ASIA）-A were studied. Orthopedic treatment of the injured vertebra（e）, internal fixation of the vertebral column, and bilateral laminectomy for epidural decompression were followed directly by neurosurgical management, including separation of the arachnoid adhesion to restore cerebrospinal fluid flow and debridement of the spinal cord necrotic tissue with concomitant intramedullary decompression. Rehabilitation started 17 days after the operation. The final outcome was evaluated after 3 months of rehabilitation. Pearson chi-square analysis was used for statistical analysis. Results All the patients recovered some ability to walk. The least recovered patients were able to walk with a wheeled weight support and help in stabilizing the weight bearing knee joint （12 cases, 40%）. Thirteen patients （43%） were able to walk with a pair of crutches, a stick or without any support. The timing of the operation after injury was important. An optimal operation time window was identified at 4-14 days after injury. Conclusions Early neurosurgical intervention of spinal cord contusion followed by rehabilitation can significantly improve the locomotion of the patients. It is a new idea of a therapeutic approach for spinal cord contusion and has been proven to be very successful.
基金Acknowledgements This work was financially supported by the National Science Foundation （No. IIP-1542995）. The authors also acknowledge Jonathan W. Crowe from Dr. Psaras L. McGrier＇s group for the help of the BET measurement.
文摘Electrochemical potassium ion intercalation into two-dimensional layered MoS2 was studied for the first time for potential applications in the anode in potassium-based batteries. X-ray diffraction analysis indicated that an intercalated potassium compound, hexagonal K0.4MoS2, formed during the intercalation process. Despite the size of K^＋, MoS2 was a long-life host for repetitive potassium ion intercalation and de-intercalation with a capacity retention of 97.5% after 200 cycles. The diffusion coefficient of the K^＋ ions in KxMoS2 was calculated based on the Randles-Sevcik equation. A higher K^＋ intercalation ratio not only encountered a much slower K^＋ diffusion rate in MoS2, but also induced MoS2 reduction. This study shows that metal dichalcogenides are promising potassium anode materials for emerging K-ion, K-O2, and K-S batteries.
文摘Background -Pretreatment is not the most common strategy practiced for clopidogrel administration in elective coronary stenting. Moreover, limited information is available on the antiplatelet pharmacodynamics of a 300-mg versus a 600-mg clopidogrel loading dose, and the comparative effect of eptifibatide with these regimens is unknown. Methods and Results -Patients undergoing elective stenting (n=120) were enrolled in a 2X2 factorial study(300 mg clopidogrel with or without eptifibatide; 600 mg clopidogrel with or without eptifibatide)(Clopidogrel Loading With Eptifibatide to Arrest the Reactivity of Platelets[CLEAR PLATELETS] Study). Clopidogrel was administered immediately after stenting. Aggregometry and flow cytometry were used to assess platelet reactivity. Eptifibatide added a ≥2-fold increase in platelet inhibition to 600 mg clopidogrel alone at 3, 8, and 18 to 24 hours after stenting as measured by 5 μmol/L ADP-induced aggregation(P< 0.001). Without eptifibatide, 600 mg clopidogrel produced better inhibition than 300 mg clopidogrel at all time points(P< 0.001). Glycoprotein IIb/IIIa(GPIIb/IIIa) blockade was associated with lower cardiac marker release. Active GPIIb/IIIa expression was inhibited most in the groups treated with eptifibatide(P< 0.05). Conclusions -In elective stenting without clopidogrel pretreatment, use of a GPIIb/IIIa inhibitor produces superior platelet inhibition and lower myocardial necrosis compared with high-dose(600 mg) or standard-dose(300 mg) clopidogrel loading alone. In the absence of a GPIIb/IIIa inhibitor, 600 mg clopidogrel provides better platelet inhibition than the standard 300-mg dose. These results require confirmation in a large-scale clinical trial.
基金supported by a grant from the National Natural Science Foundation of China(No.30571640)
文摘BACKGROUND: Fatty liver disease (FLD) is increasingly recognized as one of the most common chronic liver diseases in China. This study aimed to investigate the prevalence and risk factors of FLD in Chengdu, Southwest China, and to provide a relevant basis for the prevention and intervention of FLD. METHODS: Altogether 9094 subjects (4721 men and 4373 women) of over 18 years old who had received a medical checkup in the West China Hospital of Sichuan University between January and December 2007 were evaluated for FLD. FLD was diagnosed by ultrasonography. Body mass index (BMI), height, body weight, blood pressure, fasting plasma glucose (FPG), triglycerides (TG), total cholesterol (TCh), alanine aminotransferase (ALT), hepatitis B surface antigen (HBsAg), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were measured using routine laboratory methods. RESULTS: The overall prevalence of FLD was 12.5%, which was more than 3-fold higher in males than in females 2 (18.9% vs. 5.7%, chi(2) =359.624, P<0.001). The prevalence increased with age in females and males of less than 50 years. The prevalence of alcoholic, suspected alcoholic, and non-alcoholic FLD was 2.6%, 3.6%, and 6.3%, respectively. Multiple logistic regression analyses showed that 10 factors (male sex, age, BMI, FPG, hypertension, TG, TCh, HDL-C, LDL-C, and ALT abnormalities) were closely related to FLD. In heavy drinkers, obesity increased the risk of FLD by 23.78-fold (95% CI, 10.22-55.33), but heavy drinking was only associated with a 2-fold (95% CI, 1.50-2.66) increased risk in obese subjects. CONCLUSIONS: The prevalence of FLD among a health-checkup population in Chengdu, Southwest China was lower than the published for other areas of China. FLD in Chengdu adults was found to be closely associated with sex, age, BMI, and other metabolic syndrome features.
文摘AIM:To evaluate the detection and differentiation ability of contrast-enhanced intraoperative ultrasonography(CE-IOUS) in hepatocellular carcinoma(HCC) operations.METHODS:Clinical data of 50 HCC patients were retrospective analyzed.The sensitivity,specificity,false negative and false positive rates of contrast enhanced magnetic resonance imaging(CE-MRI),IOUS and CEIOUS were calculated and compared.Surgical strategy changes due to CE-IOUS were analyzed.RESULTS:Lesions detected by CE-MRI,IOUS and CEIOUS were 60,97 and 85 respectively.The sensitivity,specificity,false negative rate,false positive rate of CEMRI were 98.2%,98.6%,98.6%,60.0%,respectively;for IOUS were 50.0%,90.9%,1.8%,1.4%,respectively;and for CE-IOUS were 1.4%,40.0%,50.0%,9.1%,respectively.The operation strategy of 9(9/50,18.0%) cases was changed according to the results of CE-IOUS.CONCLUSION:Compared with CE-MRI,CE-IOUS performs better in detection and differentiation of small metastasis and regenerative nodules.It plays an important role in the decision-making of HCC operation.
文摘AIM:To report the incidence of non-small-bowel bleeding pathologies encountered during double-balloon enteroscopy (DBE) procedures and to analyse their significance.METHODS: A retrospective study of a prospective DBE database conducted in a tertiary-referral center was conducted. A total of 179 patients with obscure gastrointestinal bleeding (OGIB) referred for DBE from June 2004 to November 2008 were analysed looking for the incidence of non-small-bowel lesions (NSBLs; all and newly diagnosed) encountered during DBE.RESULTS: There were 228 (150 antegrade and 78 retrograde) DBE procedures performed in 179 patients. The mean number of DBE procedures was 1.27 per patient. The mean age (SD) of the patients was 62 ± 16 years old. There were 94 females (52.5%). The positive yield for a bleeding lesion was 65.9%. Of the 179 patients, 44 (24.6%) had NSBLs (19 of them had dual pathology with small-bowel lesions and NSBLs); 27 (15.1%) had lesions not detected by previous endoscopies. The most common type of missed lesions were vascular lesions.CONCLUSION: A significant proportion of patients (24.6%) had lesions within reach of conventional endoscopy. Careful repeat examination with gastroscopy and colonoscopy might be required.
基金supported by the project “The demonstration system of rich semantic search application in scientific literature” (Grant No. 1734) from the Chinese Academy of Sciences
文摘Purpose:Mo ve recognition in scientific abstracts is an NLP task of classifying sentences of the abstracts into different types of language units.To improve the performance of move recognition in scientific abstracts,a novel model of move recognition is proposed that outperforms the BERT-based method.Design/methodology/approach:Prevalent models based on BERT for sentence classification often classify sentences without considering the context of the sentences.In this paper,inspired by the BERT masked language model(MLM),we propose a novel model called the masked sentence model that integrates the content and contextual information of the sentences in move recognition.Experiments are conducted on the benchmark dataset PubMed 20K RCT in three steps.Then,we compare our model with HSLN-RNN,BERT-based and SciBERT using the same dataset.Findings:Compared with the BERT-based and SciBERT models,the F1 score of our model outperforms them by 4.96%and 4.34%,respectively,which shows the feasibility and effectiveness of the novel model and the result of our model comes closest to the state-of-theart results of HSLN-RNN at present.Research limitations:The sequential features of move labels are not considered,which might be one of the reasons why HSLN-RNN has better performance.Our model is restricted to dealing with biomedical English literature because we use a dataset from PubMed,which is a typical biomedical database,to fine-tune our model.Practical implications:The proposed model is better and simpler in identifying move structures in scientific abstracts and is worthy of text classification experiments for capturing contextual features of sentences.Originality/value:T he study proposes a masked sentence model based on BERT that considers the contextual features of the sentences in abstracts in a new way.The performance of this classification model is significantly improved by rebuilding the input layer without changing the structure of neural networks.
基金Project supported by the Sino-Australian Economic and Technical Fund
文摘The zircon Sensitive High Resolution Ion Microprobe (SHRIMP) results show that granitoid intrusions in Zhaoyc Gold Belt were emplaced at two periods of Mesozoic: Linglong and Luanjiahe types of granitic intrusions were emplaced between 160 Ma and 150 Ma (late Jurassic); Guojialing type of granodioritic intrusions, 130 Ma and 126 Ma (early Cretaceous). All the three types contain at least two major generations of inherited zircons with Precambrian ( >650 Ma) and early Mesozoic ages (200-250 Ma), respectively. The former suggests that these plu-tonic rocks are of crustal origin and that Precambrian basement with component of sialic crust up to 3.4 Ga old ( Middle Archean) exists in the region. The presence of abundant inherited zircons with early Mesozoic age indicates that the Precambrian basement was affected by a major tectono-thermal event, that is the collision of the North and South China blocks, at 250 Ma to 200 Ma. SHRIMP results also indicate that the gold mineralization in the region took place between 126 Ma and 120 Ma.
基金the National 973 Project of Chinese Ministry of Science and Technology （Grant No. 2003CB716502） the Natural Science Foundation of China （Grant No. 40399143） +1 种基金 the German Science Foundation （DFG grant No. GE 1152/2-2 , WE2850/3- 1）.
文摘Eclogite lenses in marbles from the Dabie-Sulu ultrahigh-pressure （UHP） terrane are deeply subducted meta-sedimentary rocks. Zircons in these rocks have been used to constrain the ages of prograde and UHP metamorphism during subduction, and later retrograde metamorphism during exhumation. Inherited （detrital） and metamorphic zircons were distinguished on the basis of transmitted light microscopy, cathodoluminescence （CL） imaging, trace element contents and mineral inclusions. The distribution of mineral inclusions combined with CL imaging of the metamorphic zircon make it possible to relate zircon zones （domains） to different metamorphic stages. Domain 1 consists of rounded, oblong and spindly cores with dark-luminescent images, and contains quartz eclogite facies mineral inclusion assemblages, indicating formation under high-pressure （HP） metamorphic conditions of T = 571-668℃ and P =1.7-2.02 GPa. Domain 2 always surrounds domain 1 or occurs as rounded and spindly cores with white-luminescent images. It contains coesite eclogite facies mineral inclusion assemblages, indicating formation under UHP metamorphic conditions of T = 782-849℃ and P 〉 5.5 GPa. Domain 3, with gray-luminescent images, always surrounds domain 2 and occurs as the outermost zircon rim. It is characterized by low-pressure mineral inclusion assemblages, which are related to regional amphibolite facies retrograde metamorphism of T = 600- 710℃ and P = 0.7-1.2 GPa. The three metamorphic zircon domains have distinct ages; sample H1 from the Dabie terrane yielded SHRIMP ages of 245 ± 4 Ma for domain 1, 235 ± 3 Ma for domain 2 and 215± 6 Ma for domain 3, whereas sample H2 from the Sulu terrane yielded similar ages of 244 ± 4 Ma, 233 ± 4 Ma and 214 ± 5 Ma for Domains 1, 2 and 3, respectively. The mean ages of these zones suggest that subduction to UHP depths took place over 10-11 Ma and exhumation of the rocks occurred over a period of 19-20 Ma. Thus, subduction from - 55 km to 〉 160 km deep mantle depth took place
