Direct measurement of the reaction front in chemically amplified photoresists     

Lin EK  Soles CL  Goldfarb DL  Trinque BC  Burns SD  Jones RL  Lenhart JL  Angelopoulos M  Willson CG  Satija SK  Wu WL 《Science (New York, N.Y.)》2002,297(5580):372-375

The continuing drive by the semiconductor industry to fabricate smaller structures using photolithography will soon require dimensional control at length scales comparable to the size of the polymeric molecules in the materials used to pattern them. The current technology, chemically amplified photoresists, uses a complex reaction-diffusion process to delineate patterned areas with high spatial resolution. However, nanometer-level control of this critical process is limited by the lack of direct measurements of the reaction front. We demonstrate the use of x-ray and neutron reflectometry as a general method to measure the spatial evolution of the reaction-diffusion process with nanometer resolution. Measuring compositional profiles, provided by deuterium-labeled reactant groups for neutron scattering contrast, we show that the reaction front within the material is broad rather than sharply defined and the compositional profile is altered during development. Measuring the density profile, we directly correlate the developed film structure with that of the reaction front.  相似文献   

Crystal structure of a self-spliced group II intron     

Toor N  Keating KS  Taylor SD  Pyle AM 《Science (New York, N.Y.)》2008,320(5872):77-82

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Radioactive elements on Mercury's surface from MESSENGER: implications for the planet's formation and evolution     

Peplowski PN  Evans LG  Hauck SA  McCoy TJ  Boynton WV  Gillis-Davis JJ  Ebel DS  Goldsten JO  Hamara DK  Lawrence DJ  McNutt RL  Nittler LR  Solomon SC  Rhodes EA  Sprague AL  Starr RD  Stockstill-Cahill KR 《Science (New York, N.Y.)》2011,333(6051):1850-1852

The MESSENGER Gamma-Ray Spectrometer measured the average surface abundances of the radioactive elements potassium (K, 1150 ± 220 parts per million), thorium (Th, 220 ± 60 parts per billion), and uranium (U, 90 ± 20 parts per billion) in Mercury's northern hemisphere. The abundance of the moderately volatile element K, relative to Th and U, is inconsistent with physical models for the formation of Mercury requiring extreme heating of the planet or its precursor materials, and supports formation from volatile-containing material comparable to chondritic meteorites. Abundances of K, Th, and U indicate that internal heat production has declined substantially since Mercury's formation, consistent with widespread volcanism shortly after the end of late heavy bombardment 3.8 billion years ago and limited, isolated volcanic activity since.  相似文献   

Single-cell mass cytometry of differential immune and drug responses across a human hematopoietic continuum     

Bendall SC  Simonds EF  Qiu P  Amir el-AD  Krutzik PO  Finck R  Bruggner RV  Melamed R  Trejo A  Ornatsky OI  Balderas RS  Plevritis SK  Sachs K  Pe'er D  Tanner SD  Nolan GP 《Science (New York, N.Y.)》2011,332(6030):687-696

Flow cytometry is an essential tool for dissecting the functional complexity of hematopoiesis. We used single-cell "mass cytometry" to examine healthy human bone marrow, measuring 34 parameters simultaneously in single cells (binding of 31 antibodies, viability, DNA content, and relative cell size). The signaling behavior of cell subsets spanning a defined hematopoietic hierarchy was monitored with 18 simultaneous markers of functional signaling states perturbed by a set of ex vivo stimuli and inhibitors. The data set allowed for an algorithmically driven assembly of related cell types defined by surface antigen expression, providing a superimposable map of cell signaling responses in combination with drug inhibition. Visualized in this manner, the analysis revealed previously unappreciated instances of both precise signaling responses that were bounded within conventionally defined cell subsets and more continuous phosphorylation responses that crossed cell population boundaries in unexpected manners yet tracked closely with cellular phenotype. Collectively, such single-cell analyses provide system-wide views of immune signaling in healthy human hematopoiesis, against which drug action and disease can be compared for mechanistic studies and pharmacologic intervention.  相似文献   

Discovery of a viral NLR homolog that inhibits the inflammasome     

Gregory SM  Davis BK  West JA  Taxman DJ  Matsuzawa S  Reed JC  Ting JP  Damania B 《Science (New York, N.Y.)》2011,331(6015):330-334

The NLR (nucleotide binding and oligomerization, leucine-rich repeat) family of proteins senses microbial infections and activates the inflammasome, a multiprotein complex that promotes microbial clearance. Kaposi's sarcoma-associated herpesvirus (KSHV) is linked to several human malignancies. We found that KSHV Orf63 is a viral homolog of human NLRP1. Orf63 blocked NLRP1-dependent innate immune responses, including caspase-1 activation and processing of interleukins IL-1β and IL-18. KSHV Orf63 interacted with NLRP1, NLRP3, and NOD2. Inhibition of Orf63 expression resulted in increased expression of IL-1β during the KSHV life cycle. Furthermore, inhibition of NLRP1 was necessary for efficient reactivation and generation of progeny virus. The viral homolog subverts the function of cellular NLRs, which suggests that modulation of NLR-mediated innate immunity is important for the lifelong persistence of herpesviruses.  相似文献   

A global view of gene activity and alternative splicing by deep sequencing of the human transcriptome   总被引：6，自引：0，他引：6  

Sultan M  Schulz MH  Richard H  Magen A  Klingenhoff A  Scherf M  Seifert M  Borodina T  Soldatov A  Parkhomchuk D  Schmidt D  O'Keeffe S  Haas S  Vingron M  Lehrach H  Yaspo ML 《Science (New York, N.Y.)》2008,321(5891):956-960

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Genome sequence of the PCE-dechlorinating bacterium Dehalococcoides ethenogenes     

Seshadri R  Adrian L  Fouts DE  Eisen JA  Phillippy AM  Methe BA  Ward NL  Nelson WC  Deboy RT  Khouri HM  Kolonay JF  Dodson RJ  Daugherty SC  Brinkac LM  Sullivan SA  Madupu R  Nelson KE  Kang KH  Impraim M  Tran K  Robinson JM  Forberger HA  Fraser CM  Zinder SH  Heidelberg JF 《Science (New York, N.Y.)》2005,307(5706):105-108

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Post-mortem findings in 54 cases of anesthetic associated death in cats from two spay-neuter programs in New York State     

Gerdin JA  Slater MR  Makolinski KV  Looney AL  Appel LD  Martin NM  McDonough SP 《Journal of Feline Medicine and Surgery》2011,13(12):959-966

Anesthetic-associated death (AAD) in cats is infrequent, but occurs far more frequently than in people. Post-mortem investigations of AAD in cats are uncommon, and results only sporadically published. Here we report the findings in 54 cases of AAD in cats. Significant gross and/or microscopic pre-existing disease, including pulmonary, cardiac, and systemic disease, was detected in 33% of cases. Pulmonary disease was most frequently diagnosed (24% of cases), and included cases of Aelurostrongylus abstrusus infection (9% of cases). Heart disease, including two cases of hypertrophic cardiomyopathy, was less frequent (11% of cases). Four percent died from surgical complications. No?significant gross or microscopic disease was detected in 63% of cases. Additional studies are needed to determine if these findings are representative of AAD in cats in other geographic areas or with access to veterinary care. This study demonstrates that post-mortem investigation of AADs is an important and worthwhile endeavor.  相似文献   

Phenotype management: a new approach to habitat restoration     

Jason V Watters  Sean C Lema 《Biological conservation》2003,112(3):435-445

The goal of habitat restoration is to provide environmental conditions that promote the maintenance and growth of target populations. But rarely is it considered how the allocation of resources influences the diversity of phenotypes in these populations. Here we present a framework for considering how habitat restoration can shape the development and expression of phenotypes. We call this approach phenotype management as it entails restoring the resources in a habitat to manage phenotypic diversity. Phenotype management is achieved by manipulating the spatial and temporal distribution of resources to alter the degree of competition among individuals. Differences in competition, in turn, lead to changes in phenotypic and life history expression that affect population parameters including demography and effective population size (N_e). To illustrate how phenotype management can be applied, we explore how resource distributions shape variation in phenotypes in two imperiled fishes, Pacific salmon and desert pupfish. In both examples, modulating male reproductive phenotypes changes the allocation of reproductive success among population members to subsequently affect N_e. These examples further demonstrate that whether to increase or decrease phenotypic diversity depends on the primary conservation pressures faced by the species.  相似文献   

Distribution of Metal Extractable Fractions during Anaerobic Sludge Treatment in Southern Spain WWTPs     

Solís  G. J.  Alonso  E.  Riesco  P. 《Water, air, and soil pollution》2002,140(1-4):139-156

A new European Union legislation on sludge treatment isbeing introduced that will replace the one currently in force.The control of heavy metals is an important aspect of this newlegislation. The most common methodology to examine the metalcontent of sludges is determination of total metal contentafter total or pseudo total digestion of the sludge samples.Nevertheless, this kind of analysis is not informative on theavailability or mobility of the metals; a metal speciationanalysis is therefore required. In this study, sludge samplesfrom conventional activated sludge wastewater treatment plants(WWTP) were collected at different stages of an anaerobicsludge treatment process. In these samples, the total metalcontent and the distribution of metal species were determined(Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Ti, Zn) followinga protocol of sequential extraction. Only 14% of the metalwas present in readily available forms in the treated sludges.In composted sludges, this value dropped to 6%.  相似文献