Structure of superhard tungsten tetraboride: a missing link between MB2 and MB12 higher borides.

Abstract:

:Superhard metals are of interest as possible replacements with enhanced properties over the metal carbides commonly used in cutting, drilling, and wear-resistant tooling. Of the superhard metals, the highest boride of tungsten--often referred to as WB4 and sometimes as W(1-x)B3--is one of the most promising candidates. The structure of this boride, however, has never been fully resolved, despite the fact that it was discovered in 1961--a fact that severely limits our understanding of its structure-property relationships and has generated increasing controversy in the literature. Here, we present a new crystallographic model of this compound based on refinement against time-of-flight neutron diffraction data. Contrary to previous X-ray-only structural refinements, there is strong evidence for the presence of interstitial arrangements of boron atoms and polyhedral bonding. The formation of these polyhedral--slightly distorted boron cuboctahedra--appears to be dependent upon the defective nature of the tungsten-deficient metal sublattice. This previously unidentified structure type has an intermediary relationship between MB2 and MB12 type boride polymorphs. Manipulation of the fractionally occupied metal and boron sites may provide insight for the rational design of new superhard metals.

authors

Lech AT,Turner CL,Mohammadi R,Tolbert SH,Kaner RB

doi

10.1073/pnas.1415018112

subject

Has Abstract

pub_date

2015-03-17 00:00:00

pages

3223-8

issue

11

eissn

0027-8424

issn

1091-6490

pii

1415018112

journal_volume

112

pub_type

杂志文章
  • A proteolytic pathway that controls the cholesterol content of membranes, cells, and blood.

    abstract::The integrity of cell membranes is maintained by a balance between the amount of cholesterol and the amounts of unsaturated and saturated fatty acids in phospholipids. This balance is maintained by membrane-bound transcription factors called sterol regulatory element-binding proteins (SREBPs) that activate genes encod...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章,评审

    doi:10.1073/pnas.96.20.11041

    authors: Brown MS,Goldstein JL

    更新日期:1999-09-28 00:00:00

  • Sugars modulate an unusual mode of control of the cell-wall invertase gene (Incw1) through its 3' untranslated region in a cell suspension culture of maize.

    abstract::We show here that a cell-wall invertase encoded by the Incw1 gene is regulated at both the transcriptional and posttranscriptional levels by sugars in a heterotrophic cell suspension culture of maize. The Incw1 gene encoded two transcripts: Incw1-S (small) and Incw1-L (large); the size variation was attributable to di...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.96.18.10512

    authors: Cheng WH,Taliercio EW,Chourey PS

    更新日期:1999-08-31 00:00:00

  • Tubulins from different higher plant species are immunologically nonidentical and bind colchicine differentially.

    abstract::We have initiated immunological and drug-binding studies on the tubulins from different higher plant species. Antibodies were raised against electrophoretically separated rose (Rosa sp.) tubulin alpha- and beta-subunits and characterized by immunoblot autoradiographic assays. Each IgG preparation bound to its antigen ...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.81.5.1440

    authors: Morejohn LC,Bureau TE,Tocchi LP,Fosket DE

    更新日期:1984-03-01 00:00:00

  • Myelin sheath structure and regeneration in peripheral nerve injury repair.

    abstract::Observing the structure and regeneration of the myelin sheath in peripheral nerves following injury and during repair would help in understanding the pathogenesis and treatment of neurological diseases caused by an abnormal myelin sheath. In the present study, transmission electron microscopy, immunofluorescence stain...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.1910292116

    authors: Liu B,Xin W,Tan JR,Zhu RP,Li T,Wang D,Kan SS,Xiong DK,Li HH,Zhang MM,Sun HH,Wagstaff W,Zhou C,Wang ZJ,Zhang YG,He TC

    更新日期:2019-10-29 00:00:00

  • Exquisite sensitivity of adrenocortical carcinomas to induction of ferroptosis.

    abstract::Adrenocortical carcinomas (ACCs) are rare and highly malignant cancers associated with poor survival of patients. Currently, mitotane, a nonspecific derivative of the pesticide DDT (1,1-(dichlorobiphenyl)-2,2-dichloroethane), is used as the standard treatment, but its mechanism of action in ACCs remains elusive. Here ...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.1912700116

    authors: Belavgeni A,Bornstein SR,von Mässenhausen A,Tonnus W,Stumpf J,Meyer C,Othmar E,Latk M,Kanczkowski W,Kroiss M,Hantel C,Hugo C,Fassnacht M,Ziegler CG,Schally AV,Krone NP,Linkermann A

    更新日期:2019-10-29 00:00:00

  • Basal NF-κB controls IL-7 responsiveness of quiescent naïve T cells.

    abstract::T cells are essential for immune defenses against pathogens, such that viability of naïve T cells before antigen encounter is critical to preserve a polyclonal repertoire and prevent immunodeficiencies. The viability of naïve T cells before antigen recognition is ensured by IL-7, which drives expression of the prosurv...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.1315398111

    authors: Miller ML,Mashayekhi M,Chen L,Zhou P,Liu X,Michelotti M,Tramontini Gunn N,Powers S,Zhu X,Evaristo C,Alegre ML,Molinero LL

    更新日期:2014-05-20 00:00:00

  • Differential development of large-cell neuroendocrine or small-cell lung carcinoma upon inactivation of 4 tumor suppressor genes.

    abstract::High-grade neuroendocrine lung malignancies (large-cell neuroendocrine cell carcinoma, LCNEC, and small-cell lung carcinoma, SCLC) are among the most deadly lung cancer conditions with no optimal clinical management. The biological relationships between SCLC and LCNEC are still largely unknown and a current matter of ...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.1821745116

    authors: Lázaro S,Pérez-Crespo M,Lorz C,Bernardini A,Oteo M,Enguita AB,Romero E,Hernández P,Tomás L,Morcillo MÁ,Paramio JM,Santos M

    更新日期:2019-10-29 00:00:00

  • Specific inhibition of human immunodeficiency virus type 1 replication by antisense oligonucleotides: an in vitro model for treatment.

    abstract::We have developed a culture system, simulating in vivo conditions of human immunodeficiency virus type 1 (HIV-1) infection, to evaluate the long-term efficacy of antisense oligonucleotide treatment. Five oligonucleotide phosphorothioates (28-mers), complementary to different regions of HIV-1 RNA, blocked replication o...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.89.23.11209

    authors: Lisziewicz J,Sun D,Klotman M,Agrawal S,Zamecnik P,Gallo R

    更新日期:1992-12-01 00:00:00

  • Protection of Cftr knockout mice from acute lung infection by a helper-dependent adenoviral vector expressing Cftr in airway epithelia.

    abstract::We developed a helper-dependent adenoviral vector for cystic fibrosis lung gene therapy. The vector expresses cystic fibrosis transmembrane conductance regulator (Cftr) using control elements from cytokeratin 18. The vector expressed properly localized CFTR in cultured cells and in the airway epithelia of mice. Cftr R...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.2436478100

    authors: Koehler DR,Sajjan U,Chow YH,Martin B,Kent G,Tanswell AK,McKerlie C,Forstner JF,Hu J

    更新日期:2003-12-23 00:00:00

  • CaM kinase II regulates cardiac hemoglobin expression through histone phosphorylation upon sympathetic activation.

    abstract::Sympathetic activation of β-adrenoreceptors (β-AR) represents a hallmark in the development of heart failure (HF). However, little is known about the underlying mechanisms of gene regulation. In human ventricular myocardium from patients with end-stage HF, we found high levels of phosphorylated histone 3 at serine-28 ...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.1816521116

    authors: Saadatmand AR,Sramek V,Weber S,Finke D,Dewenter M,Sticht C,Gretz N,Wüstemann T,Hagenmueller M,Kuenzel SR,Meyer-Roxlau S,Kramer M,Sossalla S,Lehmann LH,Kämmerer S,Backs J,El-Armouche A

    更新日期:2019-10-29 00:00:00

  • Inverted repeat structure of the Sry locus in mice.

    abstract::The testis-determining gene Sry is located on the short arm of the mouse Y chromosome in a region known to have undergone duplications and rearrangements in comparison with the equivalent portion of the human Y chromosome. Detailed analysis of the Sry genomic locus reveals a further difference in that the mouse Sry op...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.89.17.7953

    authors: Gubbay J,Vivian N,Economou A,Jackson D,Goodfellow P,Lovell-Badge R

    更新日期:1992-09-01 00:00:00

  • Phosphorylation of actin Tyr-53 inhibits filament nucleation and elongation and destabilizes filaments.

    abstract::Dictyostelium actin was shown to become phosphorylated on Tyr-53 late in the developmental cycle and when cells in the amoeboid stage are subjected to stress but the phosphorylated actin had not been purified and characterized. We have separated phosphorylated and unphosphorylated actin and shown that Tyr-53 phosphory...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.0606321103

    authors: Liu X,Shu S,Hong MS,Levine RL,Korn ED

    更新日期:2006-09-12 00:00:00

  • Bioarchaeology of Neolithic Çatalhöyük reveals fundamental transitions in health, mobility, and lifestyle in early farmers.

    abstract::The transition from a human diet based exclusively on wild plants and animals to one involving dependence on domesticated plants and animals beginning 10,000 to 11,000 y ago in Southwest Asia set into motion a series of profound health, lifestyle, social, and economic changes affecting human populations throughout mos...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 历史文章,杂志文章

    doi:10.1073/pnas.1904345116

    authors: Larsen CS,Knüsel CJ,Haddow SD,Pilloud MA,Milella M,Sadvari JW,Pearson J,Ruff CB,Garofalo EM,Bocaege E,Betz BJ,Dori I,Glencross B

    更新日期:2019-06-25 00:00:00

  • Endothelin 3 selectively promotes survival and proliferation of neural crest-derived glial and melanocytic precursors in vitro.

    abstract::Genetic data in the mouse have shown that endothelin 3 (ET3) and its receptor B (ETRB) are essential for the development of two neural crest (NC) derivatives, the melanocytes and the enteric nervous system. We report here the effects of ET3 in vitro on the differentiation of quail trunk NC cells (NCC) in mass and clon...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.95.24.14214

    authors: Lahav R,Dupin E,Lecoin L,Glavieux C,Champeval D,Ziller C,Le Douarin NM

    更新日期:1998-11-24 00:00:00

  • Self-assembly of smallest magnetic particles.

    abstract::The assembly of tiny magnetic particles in external magnetic fields is important for many applications ranging from data storage to medical technologies. The development of ever smaller magnetic structures is restricted by a size limit, where the particles are just barely magnetic. For such particles we report the dis...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.1511443112

    authors: Mehdizadeh Taheri S,Michaelis M,Friedrich T,Förster B,Drechsler M,Römer FM,Bösecke P,Narayanan T,Weber B,Rehberg I,Rosenfeldt S,Förster S

    更新日期:2015-11-24 00:00:00

  • Metabolic engineering with Dof1 transcription factor in plants: Improved nitrogen assimilation and growth under low-nitrogen conditions.

    abstract::Utilization of transcription factors might be a powerful approach to modification of metabolism for a generation of crops having superior characteristics because a single transcription factor frequently regulates coordinated expression of a set of key genes for respective pathways. Here, we apply the plant-specific Do...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.0402267101

    authors: Yanagisawa S,Akiyama A,Kisaka H,Uchimiya H,Miwa T

    更新日期:2004-05-18 00:00:00

  • Human eIF4E promotes mRNA restructuring by stimulating eIF4A helicase activity.

    abstract::Elevated eukaryotic initiation factor 4E (eIF4E) levels frequently occur in a variety of human cancers. Overexpression of eIF4E promotes cellular transformation by selectively increasing the translation of proliferative and prosurvival mRNAs. These mRNAs possess highly structured 5'-UTRs that impede ribosome recruitme...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.1303781110

    authors: Feoktistova K,Tuvshintogs E,Do A,Fraser CS

    更新日期:2013-08-13 00:00:00

  • NF-kappaB activation and potentiation of proinflammatory responses by the Helicobacter pylori CagA protein.

    abstract::The Helicobacter pylori immunodominant protein, CagA, is associated with severe gastritis and carcinoma. Injection of CagA into gastric epithelial cells by type IV secretion leads to actin-cytoskeletal rearrangements and cell scattering. CagA has been reported to have no role in the induction of transcription factor N...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.0409873102

    authors: Brandt S,Kwok T,Hartig R,König W,Backert S

    更新日期:2005-06-28 00:00:00

  • Present-day African analogue of a pre-European Amazonian floodplain fishery shows convergence in cultural niche construction.

    abstract::Erickson [Erickson CL (2000) Nature 408 (6809):190-193] interpreted features in seasonal floodplains in Bolivia's Beni savannas as vestiges of pre-European earthen fish weirs, postulating that they supported a productive, sustainable fishery that warranted cooperation in the construction and maintenance of perennial s...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 历史文章,杂志文章

    doi:10.1073/pnas.1613169114

    authors: McKey DB,Durécu M,Pouilly M,Béarez P,Ovando A,Kalebe M,Huchzermeyer CF

    更新日期:2016-12-27 00:00:00

  • Use of a zinc-finger consensus sequence framework and specificity rules to design specific DNA binding proteins.

    abstract::We have designed three zinc-finger proteins with different DNA binding specificities. The design strategy combines a consensus zinc-finger framework sequence with previously characterized recognition regions such that the specificity of each protein is predictable. The first protein consists of three identical zinc fi...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.90.6.2256

    authors: Desjarlais JR,Berg JM

    更新日期:1993-03-15 00:00:00

  • Towards a quantitative understanding of the late Neoproterozoic carbon cycle.

    abstract::The cycles of carbon and oxygen at the Earth surface are intimately linked, where the burial of organic carbon into sediments represents a source of oxygen to the surface environment. This coupling is typically quantified through the isotope records of organic and inorganic carbon. Yet, the late Neoproterozoic Eon, th...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 历史文章,杂志文章

    doi:10.1073/pnas.1101755108

    authors: Bjerrum CJ,Canfield DE

    更新日期:2011-04-05 00:00:00

  • Catalytic domain of human immunodeficiency virus type 1 integrase: identification of a soluble mutant by systematic replacement of hydrophobic residues.

    abstract::The integrase protein of human immunodeficiency virus type 1 is necessary for the stable integration of the viral genome into host DNA. Integrase catalyzes the 3' processing of the linear viral DNA and the subsequent DNA strand transfer reaction that inserts the viral DNA ends into host DNA. Although full-length integ...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.92.13.6057

    authors: Jenkins TM,Hickman AB,Dyda F,Ghirlando R,Davies DR,Craigie R

    更新日期:1995-06-20 00:00:00

  • Theoretical considerations on the "spine of hydration" in the minor groove of d(CGCGAATTCGCG).d(GCGCTTAAGCGC): Monte Carlo computer simulation.

    abstract::A theoretical description of aqueous hydration in the minor groove of a B-form DNA is presented on the basis of a liquid-state Monte Carlo computer simulation on a system consisting of the oligonucleotide duplex d(CGCGAATTCGCG).d(GCGCTTAAGCGC) in a canonical B-form together with 1777 water molecules contained in a hex...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.85.6.1836

    authors: Subramanian PS,Ravishanker G,Beveridge DL

    更新日期:1988-03-01 00:00:00

  • Microtubule plus-end tracking by CLIP-170 requires EB1.

    abstract::Microtubules are polarized polymers that exhibit dynamic instability, with alternating phases of elongation and shortening, particularly at the more dynamic plus-end. Microtubule plus-end tracking proteins (+TIPs) localize to and track with growing microtubule plus-ends in the cell. +TIPs regulate microtubule dynamics...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.0807614106

    authors: Dixit R,Barnett B,Lazarus JE,Tokito M,Goldman YE,Holzbaur EL

    更新日期:2009-01-13 00:00:00

  • Lack of p21 expression links cell cycle control and appendage regeneration in mice.

    abstract::Animals capable of regenerating multiple tissue types, organs, and appendages after injury are common yet sporadic and include some sponge, hydra, planarian, and salamander (i.e., newt and axolotl) species, but notably such regenerative capacity is rare in mammals. The adult MRL mouse strain is a rare exception to the...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.1000830107

    authors: Bedelbaeva K,Snyder A,Gourevitch D,Clark L,Zhang XM,Leferovich J,Cheverud JM,Lieberman P,Heber-Katz E

    更新日期:2010-03-30 00:00:00

  • Lipid- and mechanosensitivities of sodium/hydrogen exchangers analyzed by electrical methods.

    abstract::Sodium/hydrogen exchangers (NHEs) are ubiquitous ion transporters that serve multiple cell functions. We have studied two mammalian isoforms, NHE1 (ubiquitous) and NHE3 (epithelial-specific), by measuring extracellular proton (H+) gradients during whole-cell patch clamp with perfusion of the cell interior. Maximal Na(...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.0403930101

    authors: Fuster D,Moe OW,Hilgemann DW

    更新日期:2004-07-13 00:00:00

  • Observations on the pH dependence of the glutaminase activity of a glutamine amidotransferase, carbamylphosphate synthetase.

    abstract::Glutamine-dependent carbamylphosphate synthetase (Escherichia coli) is composed of a heavy subunit (molecular weight about 130,000) and a light subunit (molecular weight about 42,000), which can be separated with retention of catalytic activities. The separated heavy subunit can catalyze activation of CO(2) by ATP and...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.70.10.2717

    authors: Trotta PP,Wellner VP,Pinkus LM,Meister A

    更新日期:1973-10-01 00:00:00

  • Pupil dilation reflects perceptual selection and predicts subsequent stability in perceptual rivalry.

    abstract::During sustained viewing of an ambiguous stimulus, an individual's perceptual experience will generally switch between the different possible alternatives rather than stay fixed on one interpretation (perceptual rivalry). Here, we measured pupil diameter while subjects viewed different ambiguous visual and auditory st...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.0707727105

    authors: Einhäuser W,Stout J,Koch C,Carter O

    更新日期:2008-02-05 00:00:00

  • Planar-to-tubular structural transition in boron clusters: B20 as the embryo of single-walled boron nanotubes.

    abstract::Experimental and computational simulations revealed that boron clusters, which favor planar (2D) structures up to 18 atoms, prefer 3D structures beginning at 20 atoms. Using global optimization methods, we found that the B20 neutral cluster has a double-ring tubular structure with a diameter of 5.2 A. For the B(-)20 a...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.0408132102

    authors: Kiran B,Bulusu S,Zhai HJ,Yoo S,Zeng XC,Wang LS

    更新日期:2005-01-25 00:00:00

  • Photooxidation of cytochrome P450-BM3.

    abstract::High-valent iron-oxo species are thought to be intermediates in the catalytic cycles of oxygenases and peroxidases. An attractive route to these iron-oxo intermediates involves laser flash-quench oxidation of ferric hemes, as demonstrated by our work on the ferryl (compound II) and ferryl porphyrin radical cation (com...

    journal_title:Proceedings of the National Academy of Sciences of the United States of America

    pub_type: 杂志文章

    doi:10.1073/pnas.1012381107

    authors: Ener ME,Lee YT,Winkler JR,Gray HB,Cheruzel L

    更新日期:2010-11-02 00:00:00