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Sample records for acta cryst d65

  1. Crystallization reports are the backbone of Acta Cryst. F, but do they have any spine?

    PubMed

    Newman, Janet; Burton, Denis R; Caria, Sofia; Desbois, Sebastien; Gee, Christine L; Fazio, Vincent J; Kvansakul, Marc; Marshall, Bevan; Mills, Grant; Richter, Viviane; Seabrook, Shane A; Wu, Mingbo; Peat, Thomas S

    2013-07-01

    Crystallization of macromolecules is famously difficult. By knowing what has worked for others, researchers can ease the process, both in the case where the protein has already been crystallized and in the situation where more general guidelines are needed. The 264 crystallization communications published in Acta Crystallographica Section F in 2012 have been reviewed, and from this analysis some information about trends in crystallization has been gleaned. More importantly, it was found that there are several ways in which the utility of these communications could be increased: to make each individual paper a more complete crystallization record; and to provide a means for taking a snapshot of what the current `best practices' are in the field.

  2. Recent developments in CrystFEL 1

    PubMed Central

    White, Thomas A.; Mariani, Valerio; Brehm, Wolfgang; Yefanov, Oleksandr; Barty, Anton; Beyerlein, Kenneth R.; Chervinskii, Fedor; Galli, Lorenzo; Gati, Cornelius; Nakane, Takanori; Tolstikova, Alexandra; Yamashita, Keitaro; Yoon, Chun Hong; Diederichs, Kay; Chapman, Henry N.

    2016-01-01

    CrystFEL is a suite of programs for processing data from ‘serial crystallography’ experiments, which are usually performed using X-ray free-electron lasers (FELs) but also increasingly with other X-ray sources. The CrystFEL software suite has been under development since 2009, just before the first hard FEL experiments were performed, and has been significantly updated and improved since then. This article describes the most important improvements which have been made to CrystFEL since the first release version. These changes include the addition of new programs to the suite, the ability to resolve ‘indexing ambiguities’ and several ways to improve the quality of the integrated data by more accurately modelling the underlying diffraction physics. PMID:27047311

  3. CrystPro: Spatiotemporal Analysis of Protein Crystallization Images

    PubMed Central

    2015-01-01

    Thousands of experiments corresponding to different combinations of conditions are set up to determine the relevant conditions for successful protein crystallization. In recent years, high throughput robotic set-ups have been developed to automate the protein crystallization experiments, and imaging techniques are used to monitor the crystallization progress. Images are collected multiple times during the course of an experiment. Huge number of collected images make manual review of images tedious and discouraging. In this paper, utilizing trace fluorescence labeling, we describe an automated system called CrystPro for monitoring the protein crystal growth in crystallization trial images by analyzing the time sequence images. Given the sets of image sequences, the objective is to develop an efficient and reliable system to detect crystal growth changes such as new crystal formation and increase of crystal size. CrystPro consists of three major steps- identification of crystallization trials proper for spatio-temporal analysis, spatio-temporal analysis of identified trials, and crystal growth analysis. We evaluated the performance of our system on 3 crystallization image datasets (PCP-ILopt-11, PCP-ILopt-12, and PCP-ILopt-13) and compared our results with expert scores. Our results indicate a) 98.3% accuracy and .896 sensitivity on identification of trials for spatio-temporal analysis, b) 77.4% accuracy and .986 sensitivity of identifying crystal pairs with new crystal formation, and c) 85.8% accuracy and 0.667 sensitivity on crystal size increase detection. The results show that our method is reliable and efficient for tracking growth of crystals and determining useful image sequences for further review by the crystallographers. PMID:26640418

  4. [The thirty years of Acta Genetica Sinica].

    PubMed

    Li, Shao-Wu; Zhou, Su; Xue, Yong-Biao; Zhu, Li-Huang

    2003-04-01

    Acta Genetica Sinica (AGS) is sponsored by the Genetics Society of China and the Institute of Genetics and Developmental Biology of Chinese Academy of Sciences, and is published by Science Press. The journal is a leading national academic periodical and one of the Chinese key periodicals of natural sciences. Currently, AGS is being indexed by several well-known domestic and international indexing systems, such as the American Chemical Digest (CA), BIOSIS database, Biological Digest (BA), Medical Index and Russian Digest (P [symbol: see text]). Papers in the areas of genetics, developmental biology, cell molecular biology and evolution are regularly published by AGS.

  5. 50th Anniversary of Acta stomatologica Croatica.

    PubMed

    Brkić, Hrvoje

    2016-03-01

    Acta stomatologica Croatisa (ASCRO) is scientific-professional magazine whose first issue was published back in 1966. Ever since the magazine publishers were the School of Dental Medicine of the University of Zagreb and the Croatian Dental Association of the Croatian Medical Association. Over the past fifty years two hundred regular editions were pubslihed along with three additions. The magazine has been internationally indexed and it was granted the DOI number. In this way by means of CrossCheck possible plagiarisms are being checked which aims at obtaining originality of the published results. Another peculiarity of ASCRO is bilingualism throughout the whole edition, international recognizability, open source and tradition based on sound foundations. PMID:27688420

  6. 50th Anniversary of Acta stomatologica Croatica

    PubMed Central

    2016-01-01

    Summary Acta stomatologica Croatisa (ASCRO) is scientific-professional magazine whose first issue was published back in 1966. Ever since the magazine publishers were the School of Dental Medicine of the University of Zagreb and the Croatian Dental Association of the Croatian Medical Association. Over the past fifty years two hundred regular editions were pubslihed along with three additions. The magazine has been internationally indexed and it was granted the DOI number. In this way by means of CrossCheck possible plagiarisms are being checked which aims at obtaining originality of the published results. Another peculiarity of ASCRO is bilingualism throughout the whole edition, international recognizability, open source and tradition based on sound foundations.

  7. 50th Anniversary of Acta stomatologica Croatica

    PubMed Central

    2016-01-01

    Summary Acta stomatologica Croatisa (ASCRO) is scientific-professional magazine whose first issue was published back in 1966. Ever since the magazine publishers were the School of Dental Medicine of the University of Zagreb and the Croatian Dental Association of the Croatian Medical Association. Over the past fifty years two hundred regular editions were pubslihed along with three additions. The magazine has been internationally indexed and it was granted the DOI number. In this way by means of CrossCheck possible plagiarisms are being checked which aims at obtaining originality of the published results. Another peculiarity of ASCRO is bilingualism throughout the whole edition, international recognizability, open source and tradition based on sound foundations. PMID:27688420

  8. Entering the 60th year of Acta Astronautica

    NASA Astrophysics Data System (ADS)

    Chang, Yi-Wei; Chern, Jeng-Shing; Marec, Jean-Pierre

    2014-04-01

    The Acta Astronautica Journal was firstly published in 1955 as the official Journal of the International Astronautical Federation (IAF) with the title Astronautica Acta. It is entering its 60th year in 2014. In 1962, the Astronautica Acta became the official Journal of the International Academy of Astronautics (IAA) established in 1960. A total of 18 volumes had been published from 1955 to 1973 under the leadership of three Editor-in-Chiefs: F. Hecht, Theodore von Karman, and Martin Summerfield. In 1974, A.K. Oppenheim became the new Editor-in-Chief and several evolved changes were performed including change of the title to Acta Astronautica (for grammatical correctness), cover page change, and format change. From 1974 to 2010, another three Editor-in-Chiefs led the journal with 67 volumes published. They were A.K. Oppenheim, Jean-Pierre Marec, and Rupert Gerzer. The current Editor-in-Chief Jeng-Shing Chern (Rock) took over the job from 2011. Total pages and articles published in 2012 are 3586 and 356, respectively. Currently, the Acta Astronautica Editorial Board consists of one Editor-in-Chief, 15 Co-Editors, one Managing Editor and one Honorary Editor-in-Chief (Jean-Pierre Marec). After 59 years, the Acta Astronautica has become a well-known journal worldwide. Its current rank and impact factor are 7/63 and 0.701, respectively. This paper presents some of the details as well as new strategies and steps. In particular, supports from the IAA Academicians are mandatory and most welcome.

  9. Elsevier/Spectrochimica Acta Atomic Spectroscopy Award 2013

    NASA Astrophysics Data System (ADS)

    Omenetto, Nicolo'; de Loos, Greet

    2015-01-01

    This is to announce the 2013 Elsevier/Spectrochimica Acta Award, the annual award honoring the most significant article(s) published in a volume. Elsevier makes this award on behalf of Spectrochimica Acta, Part B, to encourage the publication of top articles in this journal. All papers published during one year are considered for this award and the Editorial Advisory Board and the Guest Editor(s) of the special issue(s) are responsible for the selection. The award consists of a monetary prize of 1000 together with a presentation certificate.

  10. Elsevier/Spectrochimica Acta Atomic Spectroscopy Award 2014

    NASA Astrophysics Data System (ADS)

    Omenetto, Nicolo'; de Loos, Greet

    2016-03-01

    This is to announce the 2014 Elsevier/Spectrochimica Acta Award, the annual award honoring the most significant article(s) published in a volume. Elsevier makes this award on behalf of Spectrochimica Acta, Part B, to encourage the publication of top articles in this journal. All papers published during one year are considered for this award and the Editorial Advisory Board and the Guest Editor(s) of the special issue(s) are responsible for the selection. The award consists of a monetary prize of 1000 together with a presentation certificate.

  11. Advertising in Actas Dermosifiliográficas, 1909-1939.

    PubMed

    Díaz-Díaz, R M

    2014-05-01

    We review advertisements published in the journal Actas Dermosifiliográficas between 1909 and 1939. Treatments for sexually transmitted diseases were advertised with particular frequency, and they offer a case in point that exemplifies the close relationship between the pharmaceutical industry and medical journals.

  12. Advertising in Actas Dermosifiliográficas, 1909-1939.

    PubMed

    Díaz-Díaz, R M

    2014-05-01

    We review advertisements published in the journal Actas Dermosifiliográficas between 1909 and 1939. Treatments for sexually transmitted diseases were advertised with particular frequency, and they offer a case in point that exemplifies the close relationship between the pharmaceutical industry and medical journals. PMID:24433815

  13. Citation Analysis of "Geochimica et Cosmochimica Acta," 1951-1960.

    ERIC Educational Resources Information Center

    Lifshin, Arthur

    1993-01-01

    A citation analysis of the first 10 years of "Geochimica et Cosmochimica Acta" from 1951 to 1960 is described. A shift from German to English language citations and the emerging importance of the journal in the field, which is undergoing a change resulting from technological innovation, are shown. Tables and graphs are included. (EAM)

  14. Comment on "Experimental study of the orientation dependence of indium incorporation in GaInN" [J. Cryst. Growth 433 (2016) 7-12

    NASA Astrophysics Data System (ADS)

    Monavarian, Morteza

    2016-07-01

    The authors of the title paper (J. Cryst. Growth 433 (2016) 7-12) reported on experimental comparison of indium incorporation efficiency in wide variety of orientations tilted from the basal plane toward a-plane (a-family planes) or m-plane (m-family planes) and some mixed planes. Despite a good investigation and useful information reported in this manuscript, some points of criticism, concerning the inclination angle calculations, optical characterizations of the layers, and the final conclusions are highlighted in this comment to consider.

  15. Mouse models of dominant ACTA1 disease recapitulate human disease and provide insight into therapies.

    PubMed

    Ravenscroft, Gianina; Jackaman, Connie; Bringans, Scott; Papadimitriou, John M; Griffiths, Lisa M; McNamara, Elyshia; Bakker, Anthony J; Davies, Kay E; Laing, Nigel G; Nowak, Kristen J

    2011-04-01

    Mutations in the skeletal muscle α-actin gene (ACTA1) cause a range of pathologically defined congenital myopathies. Most patients have dominant mutations and experience severe skeletal muscle weakness, dying within one year of birth. To determine mutant ACTA1 pathobiology, transgenic mice expressing ACTA1(D286G) were created. These Tg(ACTA1)(D286G) mice were less active than wild-type individuals. Their skeletal muscles were significantly weaker by in vitro analyses and showed various pathological lesions reminiscent of human patients, however they had a normal lifespan. Mass spectrometry revealed skeletal muscles from Tg(ACTA1)(D286G) mice contained ∼25% ACTA1(D286G) protein. Tg(ACTA1)(D286G) mice were crossed with hemizygous Acta1(+/-) knock-out mice to generate Tg(ACTA1)(D286G)(+/+).Acta1(+/-) offspring that were homozygous for the transgene and hemizygous for the endogenous skeletal muscle α-actin gene. Akin to most human patients, skeletal muscles from these offspring contained approximately equal proportions of ACTA1(D286G) and wild-type actin. Strikingly, the majority of these mice presented with severe immobility between postnatal Days 8 and 17, requiring euthanasia. Their skeletal muscles contained extensive structural abnormalities as identified in severely affected human patients, including nemaline bodies, actin accumulations and widespread sarcomeric disarray. Therefore we have created valuable mouse models, one of mild dominant ACTA1 disease [Tg(ACTA1)(D286G)], and the other of severe disease, with a dramatically shortened lifespan [Tg(ACTA1)(D286G)(+/+).Acta1(+/-)]. The correlation between mutant ACTA1 protein load and disease severity parallels effects in ACTA1 families and suggests altering this ratio in patient muscle may be a therapy for patients with dominant ACTA1 disease. Furthermore, ringbinden fibres were observed in these mouse models. The presence of such features suggests that perhaps patients with ringbinden of unknown genetic

  16. A de novo dominant mutation in ACTA1 causing congenital nemaline myopathy associated with a milder phenotype: expanding the spectrum of dominant ACTA1 mutations.

    PubMed

    Levesque, L; Del Bigio, M R; Krawitz, S; Mhanni, A A

    2013-03-01

    We describe the presentation and six-year follow up of a child with nemaline myopathy due to a de novo mutation in the skeletal muscle α-actin gene (ACTA1) characterized by dramatic improvement during the early childhood years. The presentation in this female patient was infantile-onset weakness in the facial, bulbar, respiratory and neck flexor muscles. A six-year follow-up revealed continued progressive improvement in her muscle strength. Based upon the histopathologic and ultrastructural features of nemaline rod disease, ACTA1 was sequenced. This revealed a mutation in exon 4 of ACTA1 (c.557A>G). Our report further expands the phenotypic spectrum associated with ACTA1 mutations. Although it is difficult to infer any genotype-phenotype correlation, this report stimulates the discussion regarding the pathophysiologic mechanism of the clinical improvement seen in some patients with ACTA1 mutations. PMID:23305948

  17. Acta stomatologica Croatica and PubMed Central

    PubMed Central

    Brkić, Hrvoje

    2016-01-01

    April 15 2016 marked the 50th anniversary of continuous publishing of the journal Acta stomatologica Croatica (ASCRO). The celebration was held in the great hall of the Croatian Medical Association, with numerous guests from the biomedical field. The history of the journal was presented by Goran Knežević (editor-in-chief 1996-2006) and Hrvoje Brkić (current editor-in-chief), who presented all the current information on the electronical editing and its current indexation. Only a few days later, the Editorial Office received the information that ASCRO has been included in PubMed Central since volume 48, an impulse for the members of the Editorial Board and the Editor-in-Chief to make ASCRO better and more cited

  18. Smooth Muscle α Actin (Acta2) and Myofibroblast Function during Hepatic Wound Healing

    PubMed Central

    Rockey, Don C.; Weymouth, Nate; Shi, Zengdun

    2013-01-01

    Smooth muscle α actin (Acta2) expression is largely restricted to smooth muscle cells, pericytes and specialized fibroblasts, known as myofibroblasts. Liver injury, associated with cirrhosis, induces transformation of resident hepatic stellate cells into liver specific myofibroblasts, also known as activated cells. Here, we have used in vitro and in vivo wound healing models to explore the functional role of Acta2 in this transformation. Acta2 was abundant in activated cells isolated from injured livers but was undetectable in quiescent cells isolated from normal livers. Both cellular motility and contraction were dramatically increased in injured liver cells, paralleled by an increase in Acta2 expression, when compared with quiescent cells. Inhibition of Acta2 using several different techniques had no effect on cytoplasmic actin isoform expression, but led to reduced cellular motility and contraction. Additionally, Acta2 knockdown was associated with a significant reduction in Erk1/2 phosphorylation compared to control cells. The data indicate that Acta2 is important specifically in myofibroblast cell motility and contraction and raise the possibility that the Acta2 cytoskeleton, beyond its structural importance in the cell, could be important in regulating signaling processes during wound healing in vivo. PMID:24204762

  19. Recessive ACTA1 variant causes congenital muscular dystrophy with rigid spine.

    PubMed

    O'Grady, Gina L; Best, Heather A; Oates, Emily C; Kaur, Simranpreet; Charlton, Amanda; Brammah, Susan; Punetha, Jaya; Kesari, Akanchha; North, Kathryn N; Ilkovski, Biljana; Hoffman, Eric P; Clarke, Nigel F

    2015-06-01

    Variants in ACTA1, which encodes α-skeletal actin, cause several congenital myopathies, most commonly nemaline myopathy. Autosomal recessive variants comprise approximately 10% of ACTA1 myopathy. All recessive variants reported to date have resulted in loss of skeletal α-actin expression from muscle and severe weakness from birth. Targeted next-generation sequencing in two brothers with congenital muscular dystrophy with rigid spine revealed homozygous missense variants in ACTA1. Skeletal α-actin expression was preserved in these patients. This report expands the clinical and histological phenotype of ACTA1 disease to include congenital muscular dystrophy with rigid spine and dystrophic features on muscle biopsy. This represents a new class of recessive ACTA1 variants, which do not abolish protein expression. PMID:25182138

  20. Acta Clinica Croatica: progress of a journal step by step.

    PubMed

    Ramljak, Gordana

    2014-03-01

    The journal Acta Clinica Croatica (ACC) was founded in 1962 under the title Anali Bolnice Dr. M. Stojanović. In 1995, the title of the journal was changed into its present form and ever since all papers have been published in English. In 2000, the electronic (online) edition of the ACC was released in addition to the print version. The paper presents development of the journal from 1962 to 2012 based on the analysis of the following SCOPUS citation index parameters: type and number of documents published in the journal; number of citations; and number of domestic and foreign authors. The studied period was analyzed in three time segments: the period from 1995 to 1999, the period from 2000 to 2006 and the period from 2007 to 2012. The same parameters were analyzed in the Web of Science/SCI-Expanded bibliographic and citation index for the 2007-2012 period. The increasing number of documents, authors (both domestic and foreign) and citations demonstrates gradual rise in the quality, visibility and impact of the journal. The fifty years of experience show that a goal, at first very distant and almost unachievable, may be reached by progressing step by step.

  1. Novel large deletion in the ACTA1 gene in a child with autosomal recessive nemaline myopathy.

    PubMed

    Friedman, Bethany; Simpson, Kara; Tesi-Rocha, Carolina; Zhou, Delu; Palmer, Cheryl A; Suchy, Sharon F

    2014-04-01

    Nemaline myopathy (NM) is a genetically and clinically heterogeneous disorder resulting from a disruption of the thin filament proteins of the striated muscle sarcomere. The disorder is typically characterized by muscle weakness including the face, neck, respiratory, and limb muscles and is clinically classified based on the age of onset and severity. Mutations in the ACTA1 gene contribute to a significant proportion of NM cases. The majority of ACTA1 gene mutations are missense mutations causing autosomal dominant NM by producing an abnormal protein. However, approximately 10% of ACTA1 gene mutations are associated with autosomal recessive NM; these mutations are associated with loss of protein function. We report the first case of a large deletion in the ACTA1 gene contributing to autosomal recessive NM. This case illustrates the importance of understanding disease mechanisms at the molecular level to accurately infer the inheritance pattern and potentially aid with clinical management. PMID:24447884

  2. Acta informatica medica is indexed in pubmed and archived in pubmed central.

    PubMed

    Masic, Izet

    2013-03-01

    Acta Informatica Medica journal has been accepted for archiving in PubMed Central from 2011 onward. The journal started in 1993 as the official journal of the Society for Medical Informatics of Bosnia and Herzegovina. During the last 3 years, Acta Informatica Medica has een included in almost all prestigious online databases, including PubMed, Scopus and EMBASE. The 20th volume of the journal is fully international, with papers from 18 countries.

  3. Bacterial Shape and ActA Distribution Affect Initiation of Listeria monocytogenes Actin-Based Motility

    PubMed Central

    Rafelski, Susanne M.; Theriot, Julie A.

    2005-01-01

    We have examined the process by which the intracellular bacterial pathogen Listeria monocytogenes initiates actin-based motility and determined the contribution of the variable surface distribution of the ActA protein to initiation and steady-state movement. To directly correlate ActA distributions to actin dynamics and motility of live bacteria, ActA was fused to a monomeric red fluorescent protein (mRFP1). Actin comet tail formation and steady-state bacterial movement rates both depended on ActA distribution, which in turn was tightly coupled to the bacterial cell cycle. Motility initiation was found to be a highly complex, multistep process for bacteria, in contrast to the simple symmetry breaking previously observed for ActA-coated spherical beads. F-actin initially accumulated along the sides of the bacterium and then slowly migrated to the bacterial pole expressing the highest density of ActA as a tail formed. Early movement was highly unstable with extreme changes in speed and frequent stops. Over time, saltatory motility and sensitivity to the immediate environment decreased as bacterial movement became robust at a constant steady-state speed. PMID:15980176

  4. Beitraege zur Astronomiegeschichte, Band 5 (Acta Historica Astronomiae Vol. 18)

    NASA Astrophysics Data System (ADS)

    Duerbeck, H. W.; Dick, W. R.; Hamel, J.

    2003-01-01

    The 18th volume of the Acta Historica Astronomiae is at the same time the sixth collection of essays on the history of astronomy ("Beitræge zur Astronomiegeschichte, Band 6"), edited by the historians of astronomy W.R. Dick (Potsdam) and J. Hamel (Berlin). Besides a few short notices and book reviews, the book contains eight major articles, which deal with astronomical topics covering the time from the 16th to the 19th centuries. The first article by Michael Weichenhan (Berlin) deals with "the invention of the disk-shaped earth: a chapter of Copernican apologetics". The author shows that the concept of a "disc-shaped Earth" was by no means widespread in the middle ages, but restricted to the father of the church Lactantius and some adherents. Nevertheless, it was used by adherents of Copernicus to show the absurd consequences of a strictly literal biblical interpretation -- here concerning the Earth's shape, disc versus sphere, there the geocentric versus the heliocentric system. This thorough philosophical study is followed by two very short articles. "The measuring accuracy of Tycho's large sextant" by Johann Wünsch investigates O-C values of planet-star distances, as based on Tycho's observations as published in the Historia Coelestis (a compilation, which is also based on Tycho's manuscripts, and published in Regensburg in 1672). The result is that standard deviations are 80 arcseconds for Saturn and 89 arcseconds for Jupiter and Mars, an unexpectedly poor result in view of the general opinion that Tycho was famous for his precision work. "The astronomer Christoph Grienberger and the Galilei trial" by Franz Daxecker deals with a Jesuit astronomer who was both the disciple and successor of the mathematician-astronomer Christopher Clavius at the Collegium Romanum. While he was inclined to Galilei early on, he was forced to propagate Aristotelian doctrine. The brief article is very concise, but extremely tiresome to read (3 pages of pure text are embellished by

  5. Mutations in smooth muscle alpha-actin (ACTA2) lead to thoracic aortic aneurysms and dissections.

    PubMed

    Guo, Dong-Chuan; Pannu, Hariyadarshi; Tran-Fadulu, Van; Papke, Christina L; Yu, Robert K; Avidan, Nili; Bourgeois, Scott; Estrera, Anthony L; Safi, Hazim J; Sparks, Elizabeth; Amor, David; Ades, Lesley; McConnell, Vivienne; Willoughby, Colin E; Abuelo, Dianne; Willing, Marcia; Lewis, Richard A; Kim, Dong H; Scherer, Steve; Tung, Poyee P; Ahn, Chul; Buja, L Maximilian; Raman, C S; Shete, Sanjay S; Milewicz, Dianna M

    2007-12-01

    The major function of vascular smooth muscle cells (SMCs) is contraction to regulate blood pressure and flow. SMC contractile force requires cyclic interactions between SMC alpha-actin (encoded by ACTA2) and the beta-myosin heavy chain (encoded by MYH11). Here we show that missense mutations in ACTA2 are responsible for 14% of inherited ascending thoracic aortic aneurysms and dissections (TAAD). Structural analyses and immunofluorescence of actin filaments in SMCs derived from individuals heterozygous for ACTA2 mutations illustrate that these mutations interfere with actin filament assembly and are predicted to decrease SMC contraction. Aortic tissues from affected individuals showed aortic medial degeneration, focal areas of medial SMC hyperplasia and disarray, and stenotic arteries in the vasa vasorum due to medial SMC proliferation. These data, along with the previously reported MYH11 mutations causing familial TAAD, indicate the importance of SMC contraction in maintaining the structural integrity of the ascending aorta.

  6. Review of the Journal Acta Informatica Medica During Eight Year Period: 2008-2015

    PubMed Central

    Masic, Izet; Begic, Edin; Zunic, Lejla

    2016-01-01

    Introduction: Acta Informatica Medica is official journal of the Academy for Medical Sciences of Bosnia and Herzegovina (from 2014 Acta Inform Med is published bimonthly). Aim: To evaluate journal “Acta Informatica Medica” in 2015 and compare findings to previous years. Material and methods: The study has retrospective and descriptive character, and included the period 2008-2015 (included 36 issues of journal). Results: A total of 83 (average 13,8 articles per journal) articles were published in Acta Informatica Medica during 2015. Analyzing the type of articles, original articles are present in majority during 2015 (68,6%) (by analyzing last eight years, 310 (67,3%) were original). During 2015, 27,7% of articles were related to the applied of Health informatics in field of clinical medicine, 63,8% preclinical medicine and 8,5% to public health. Collaboration rate in 2015 was 0,84. Most often the time required for decision on acceptance of article in 2015 is between 50 and 60 days. Articles came from 16 countries. According to scimagojr.com for 2014, Acta Informatica Medica has SCImago Journal Rank 0,166, while Cites / Doc. (2 years) parameter (widely used as impact index) is 0,70. According to GoogleScholar, h5 index is 11 and h5 median is 19. We analyzed the Acta Informatica Medica by “Publish or Perish” software - H index was 14, g index was 19 and e-index was 10.39. Conclusion: Year after year the highest number of original articles are published. Although the period of revision of articles is acceptable, the period up to two months is certainly not long, the goal is to reduce this period. Although the magazine in mentioned field found its place, although it is indexed in numerous bases, including: PubMed, PubMed Central, SCOPUS, EMBASE, EBSCO, etc. The main goal for next year is that the magazine becomes part of the Web of Science. Imperative is further internationalization of the magazine. PMID:27147796

  7. Novel MYH11 and ACTA2 mutations reveal a role for enhanced TGFβ signaling in FTAAD

    PubMed Central

    Renard, Marjolijn; Callewaert, Bert; Baetens, Machteld; Campens, Laurence; MacDermot, Kay; Fryns, Jean-Pierre; Bonduelle, Maryse; Dietz, Hal; Gaspar, Isabel Mendes; Cavaco, Diogo; Stattin, Eva-Lena; Schrander-Stumpel, Constance; Coucke, Paul; Loeys, Bart; De Paepe, Anne; De Backer, Julie

    2011-01-01

    Background Thoracic aortic aneurysm / dissection (TAAD) is a common phenotype that may occur as an isolated manifestation or within the constellation of a defined syndrome. In contrast to syndromic TAAD, the elucidation of the genetic basis of isolated TAAD has only recently started. To date, defects have been found in genes encoding extracellular matrix proteins (fibrillin-1, FBN1; collagen type III alpha 1, COL3A1), proteins involved in transforming growth factor beta (TGFβ) signaling (TGFβ receptor 1 and 2, TGFBR1/2; and SMAD3) or proteins that build up the contractile apparatus of aortic smooth muscle cells (myosin heavy chain 11, MYH11; smooth muscle actin alpha 2, ACTA2; and MYLK). Methods and results In 110 non-syndromic TAAD patients that previously tested negative for FBN1 or TGFBR1/2 mutations, we identified 7 ACTA2 mutations in a cohort of 43 familial TAAD patients, including 2 premature truncating mutations. Sequencing of MYH11 revealed an in frame splice-site alteration in one out of two probands with TAA(D) associated with PDA but none in the series of 22 probands from the cohort of 110 patients with non-syndromic TAAD. Interestingly, immunohistochemical staining of aortic biopsies of a patient and a family member with MYH11 and patients with ACTA2 missense mutations showed upregulation of the TGFβ signaling pathway. Conclusions MYH11 mutations are rare and typically identified in patients with TAAD associated with PDA. ACTA2 mutations were identified in 16% of a cohort presenting familial TAAD. Different molecular defects in TAAD may account for a different pathogenic mechanism of enhanced TGFβ signaling. PMID:21937134

  8. [National and international impact factor of Actas Españolas de Psiquiatría].

    PubMed

    Aleixandre Benavent, R; Valderrama Zurián, J C; Castellano Gómez, M; Simó Meléndez, R; Navarro Molina, C

    2004-01-01

    The aim of this paper is to present the bibliometric indicators of Actas Españolas de Psiquiatría that were obtained from the study "Potential impact factor of the Spanish medical journals in 2001", financed by the Spanish Ministerio de Educación, Cultura y Deporte. The citations made in Actas Españolas de Psiquiatría and its national and international impact factor and immediacy index have been obtained by the use of a methodology similar to the one used by the Institute for Scientific Information. The national indicators only take into account the citations made in 87 Spanish journals considered as sources, while those from the foreign source journals of Science Citation Index have been added to the previously cited ones. Actas Españolas de Psiquiatría has obtained a national impact factor of 0.315 and an international impact factor of 0.395, which places it as a leader in the Spanish psychiatric journals.

  9. Zebra body myopathy is caused by a mutation in the skeletal muscle actin gene (ACTA1).

    PubMed

    Sewry, C A; Holton, J L; Dick, D J; Muntoni, F; Hanna, M G

    2015-05-01

    We present follow up data on the original case of 'zebra body myopathy' published by Lake and Wilson in 1975. Pathological features in a second biopsy performed at the age of 29 years included a wide variation in fibre size, multiple split fibres, excess internal nuclei and endomysial connective tissue, rimmed vacuoles, accumulation of myofibrillar material and large 'wiped out' areas lacking stain for oxidative enzymes. The presence of nemaline rods and actin-like filaments in addition to small zebra bodies suggested ACTA1 as a candidate gene. This has been confirmed by the identification of a novel c.1043T.p.Leu348Gln mutation, which probably occurred de novo. This case illustrates that the myopathy associated with zebra bodies is part of the spectrum of myopathies associated with the ACTA1 gene. It also highlights that accumulation of actin filaments is not confined to severe neonatal ACTA1 cases and that progression of weakness can occur in congenital myopathies, as the patient is now wheelchair bound and can only stand with the aid of a walking frame. PMID:25747004

  10. Choosing orientation: influence of cargo geometry and ActA polarization on actin comet tails

    PubMed Central

    Lacayo, Catherine I.; Soneral, Paula A. G.; Zhu, Jie; Tsuchida, Mark A.; Footer, Matthew J.; Soo, Frederick S.; Lu, Yu; Xia, Younan; Mogilner, Alexander; Theriot, Julie A.

    2012-01-01

    Networks of polymerizing actin filaments can propel intracellular pathogens and drive movement of artificial particles in reconstituted systems. While biochemical mechanisms activating actin network assembly have been well characterized, it remains unclear how particle geometry and large-scale force balance affect emergent properties of movement. We reconstituted actin-based motility using ellipsoidal beads resembling the geometry of Listeria monocytogenes. Beads coated uniformly with the L. monocytogenes ActA protein migrated equally well in either of two distinct orientations, with their long axes parallel or perpendicular to the direction of motion, while intermediate orientations were unstable. When beads were coated with a fluid lipid bilayer rendering ActA laterally mobile, beads predominantly migrated with their long axes parallel to the direction of motion, mimicking the orientation of motile L. monocytogenes. Generating an accurate biophysical model to account for our observations required the combination of elastic-propulsion and tethered-ratchet actin-polymerization theories. Our results indicate that the characteristic orientation of L. monocytogenes must be due to polarized ActA rather than intrinsic actin network forces. Furthermore, viscoelastic stresses, forces, and torques produced by individual actin filaments and lateral movement of molecular complexes must all be incorporated to correctly predict large-scale behavior in the actin-based movement of nonspherical particles. PMID:22219381

  11. [Sibling cases of severe infantile form of nemaline myopathy with ACTA1-gene mutation].

    PubMed

    Sudo, Akira; Hayashi, Yukiko; Sano, Hitomi; Kawamura, Nobuaki; Nishino, Ichizo; Nonaka, Ikuya

    2013-11-01

    Severe infantile form of nemaline myopathy is clinically characterized by marked muscle hypotonia and weakness with respiratory and feeding difficulties since infancy. Recently, mutations in the skeletal muscle alpha-actine gene (ACTA1) have been identified in many patients with the nemaline myopathy. We experienced two cases of severe infantile form of nemaline myopathy with ACTA1 mutation (missence heterozygous mutation;c.553C>T, p.R185C) in siblings presenting with different clinical symptoms and courses. The elder brother was a typical "floppy infant" at birth. Because he could not suck and swallow at all, he was fed completely through a nasogastric tube. At 2 months of age, he developed respiratory insufficiency and was placed on a respirator all day. He was diagnosed with having nemaline myopathy from his muscle biopsy, which revealed marked variation in muscle fiber size with large numbers of nemaline bodies on Gomori-trichrome stain. In contrast, the younger brother presented with mild muscular hypotonia and feeding difficulty during the neonatal stage;therefore, he was partly fed through a nasogastric tube. At 2 months of age, he was admitted to our hospital because of respiratory distress, and he required nasal continuous positive airway pressure with oxygen followed by noninvasive positive pressure ventilation intermittently, mainly at night. He was followed at his home by parents with no serious problems;however he unexpectedly died at the age of 15 months. Although most cases of severe infantile form of nemaline myopathy caused by ACTA1 mutations are sporadic and have no family history, we emphasize that clinical symptoms are variable in siblings with the same mutation. PMID:24313005

  12. Evidence implicating the 5' untranslated region of Listeria monocytogenes actA in the regulation of bacterial actin-based motility.

    PubMed

    Wong, Kendy K Y; Bouwer, H G Archie; Freitag, Nancy E

    2004-02-01

    The ActA protein of Listeria monocytogenes is a major virulence factor, essential for the recruitment and polymerization of host actin filaments that lead to intracellular motility and cell-to-cell spread of bacteria within the infected host. The expression of actA is tightly regulated and is strongly induced only when L. monocytogenes is within the host cytosol. Intracellular induction of actA expression is mediated through a single promoter element that directs the expression of a messenger RNA with a long (150 bp) 5' untranslated region (UTR). Deletion of the actA+3 to +130 upstream region was found to result in bacterial mutants that were no longer capable of intracellular actin recruitment or cell-to-cell spread, thus indicating that this region is important for actA expression. L. monocytogenes strains that contained smaller deletions (21-23 bp) within the actA upstream region demonstrated a range of actA expression levels that coincided with the amount of bacterial cell-to-cell spread observed within infected monolayers. A correlation appeared to exist between levels of actA expression and the ability of L. monocytogenes to transition from uniform actin accumulation surrounding individual bacteria (actin clouds) to directional assembly and the formation of actin tails. Bacterial mutants containing deletions that most significantly altered the predicted secondary structure of the actA mRNA 5' UTR had the largest reductions in actA expression. These results suggest that the actA 5' UTR is required for maximal ActA synthesis and that a threshold level of ActA synthesis must be achieved to promote the transition from bacteria-associated actin clouds to directional actin assembly and movement.

  13. Twins with progressive thoracic aortic aneurysm, recurrent dissection and ACTA2 mutation.

    PubMed

    Ware, Stephanie M; Shikany, Amy; Landis, Benjamin J; James, Jeanne F; Hinton, Robert B

    2014-10-01

    Thoracic aortic aneurysm (TAA) is a genetically mediated disease with variable age of onset. In the pediatric age range, nonsyndromic TAA frequently has a milder course than syndromic forms of TAA, such as Marfan syndrome or Loeys-Dietz syndrome. Herein, we describe 17-year-old identical twin brothers with severe progressive TAA due to a novel de novo ACTA2 mutation. Interestingly, both boys were diagnosed at age 11 with congenital mydriasis, a recently recognized manifestation of some ACTA2 mutations due to smooth muscle dysfunction. One of the brothers presented with acute-onset lower back pain that was identified as dissection of an abdominal aortic aneurysm. Imaging of the chest at this time showed severe fusiform TAA. Cardiac imaging in his twin showed similar TAA, but no abdominal aortic aneurysm. Both brothers underwent valve-sparing aortic root replacement, but have had progressive aortic disease with recurrent dissection requiring multiple surgeries. This case emphasizes the importance of identifying physical stigmata of smooth muscle dysfunction, such as mydriasis, as potential markers for associated aortopathy and vascular diseases.

  14. Nemaline myopathy and non-fatal hypertrophic cardiomyopathy caused by a novel ACTA1 E239K mutation.

    PubMed

    Kim, Sun-Young; Park, Young-Eun; Kim, Hyang-Sook; Lee, Chang-Hoon; Yang, Dong Heon; Kim, Dae-Seong

    2011-08-15

    A twenty-year old male presented with diffuse limb muscle weakness and exertional dyspnea since childhood. The diagnosis of nemaline myopathy was given based on the muscle pathology findings that revealed nemaline rods on light and electron microscopy and discovery of a novel mutation, E239K, in ACTA1. Incidentally, the patient had hypertrophic cardiomyopathy (HCM) as shown by echocardiography. In nemaline myopathy, a few cases of HCM have been reported, albeit rarely and always fatal, but only one patient had ACTA1 mutation. This present report describes an infantile onset of nemaline myopathy with a milder clinical course and non-fatal HCM as compared with previous cases, showing clinical diversity in skeletal and cardiac manifestations of conditions associated with ACTA1 mutations. PMID:21570694

  15. Association between ACTA1 candidate gene and performance, organs and carcass traits in broilers.

    PubMed

    Venturini, G C; Stafuzza, N B; Cardoso, D F; Baldi, F; Ledur, M C; Peixoto, J O; El Faro, L; Munari, D P

    2015-12-01

    This study investigates the genetic association of the SNP present in the ACTA1 gene with performance traits, organs and carcass of broilers to help marker-assisted selection of a paternal broiler line (TT) from EMBRAPA Swine and Poultry, Brazil. Genetic and phenotypic data of 1,400 broilers for 68 traits related to body performance, organ weights, weight of carcass parts, and yields as a percentage of organs and carcass parts were used. The maximum likelihood method, considering 4 analytical models, was used to analyze the genetic association between the SNP and these important economic traits. The association analysis was performed using a mixed animal model including the random effect of the animal (polygenic), and the fixed effects of sex (2 levels), hatch (5 levels) and SNP (3 levels), besides the random error. The traits significantly associated (P<0.05) with the SNP were analyzed, along with body weight at 42 days of age (BW42), by the restricted maximum likelihood method using the multi-trait animal model to estimate genetic parameters. The analysis included the residual and additive genetic random effects and the sex-hatch fixed effect. The additive effects of the SNP were associated with breast meat (BMY), liver yield (LIVY), body weight at 35 days of age (BW35); drumstick skin (DSW), drumstick (DW) and breast (BW) weights. The heritability estimates for these traits, in addition to BW42, ranged from 0.24±0.06 to 0.45±0.08 for LIVY and BW35, respectively. The genetic correlation ranged from 0.02±0.18 for LIVY and BMY to 0.97±0.01 for BW35 and BW42. Based on the results of this study, it can be concluded that ACTA1 gene is associated with performance traits BW35, LIV and BMY, DW, BW and DW adjusted for body weight at 42 days of age. Therefore, the ACTA1 gene is an important molecular marker that could be used together with others already described to increase the economically important traits in broilers.

  16. [History of Actas Dermo-Sifiliográficas, part I: 1909-1959].

    PubMed

    Del Río, E

    2011-11-01

    Actas Dermo-Sifiliográficas was born in May 1909. At first, issues appeared in step with the academic year, but publication began to follow the calendar year in 1957. Volume 18 was skipped in 1926-7 in an effort to correct confusion in the numbering of volumes and pages of earlier issues. October 1928 saw the journal grow from 6 issues per year to 9. Although the Spanish Civil War brought publication to a halt during the 1936-7 academic year, Actas Dermo-Sifiliográficas was one of the first Spanish scientific journals to recover from the conflict. The initial print run of 100 copies was increased to 700 after the war. The content evolved over time: while originally conceived to provide a strict account of sessions of the Spanish Academy of Dermatology and Venereology (AEDV) -originally known as the Spanish Academy of Dermatology and Syphilology- the journal gradually came to include review articles, case reports, a section summarizing the content of international journals, news and various other types of writing. The editorial board and the association's board of directors were one and the same for many years. According to the earliest charter, the editor-in-chief was also the president of the association and the associate editor was the association's vice-president. The subjects of articles provide a faithful portrait of how the specialty has changed. Syphilis, a main concern before the introduction of penicillin in the 1940s, was sidelined afterwards. The appearance of 20th-century pharmaceuticals such as salvarsan, sulfa drugs, thiazides, and corticosteroids were soon reflected in the number of articles describing their use. Certain original contributions by Spanish authors to international dermatology first appeared in Actas Dermo-Sifiliográficas. Examples are Azúa's description of pseudoepithelioma and Covisa and Bejarano's of chancriform pyoderma. Volume 50 (1959), which included accounts of the 50th anniversary of the association and the journal, closed

  17. Publications on Albert Einstein, cosmology and theory of relativity in Acta Historica Astronomiae. An annotated bibliography. (German Title: Publikationen zu Albert Einstein, Kosmologie und Relativitätstheorie in Acta Historica Astronomiae. Eine annotierte Bibliographie)

    NASA Astrophysics Data System (ADS)

    Dick, Wolfgang R.

    This bibliography lists 15 publications which appeared in volumes 1 to 26 (1998 to 2005) in the series ``Acta Historica Astronomiae''. They concern life and work of Albert Einstein as well as the history of and modern developments in the theory of relativity and relativistic cosmology.

  18. Book Review: Beitraege zur Astronomiegeschichte, Band 5 (Acta Historica Astronomiae Vol. 15)

    NASA Astrophysics Data System (ADS)

    Duerbeck, H. W.; Dick, W. R.; Hamel, J.

    2002-12-01

    The 15th volume of the Acta Historica Astronomiae is at the same time the fifth collection of essays on the history of astronomy (Beitraege zur Astronomiegeschichte, Band 5), edited by the historians of astronomy W.R. Dick (Potsdam) and J. Hamel (Berlin). Besides a few short notices and book reviews, the book contains 11 major articles, which deal with astronomical topics covering the time from the 16th to the 20th centuries. The first article, on the analysis and interpretation of historical horoscopes as a source of the history of science, is based on the inaugural lecture of its author, Guenther Oestmann. After a general introduction, which deals with the principles of horoscope making, the author discusses the horoscope of Count Heinrich Ranzau (1526-1598), the Danish governor of Schleswig-Holstein, who was a friend of Tycho Brahe. Oestmann shows that the astronomical-mathematical basis of such a horoscope can be reconstructed and interpreted. However, it is hardly possible to gain an insight in the process how the interpretation of a horoscope was done in detail. The second and third articles, by Franz Daxecker, deal with Athanasius Kircher and Christoph Scheiner, two catholic astronomers of the 17th century. Kircher's Organum Mathematicum is a calculating device that can be used in the fields of arithmetic, geometry, chronology, astronomy, astrology and others. The author provides extracts of the description of the Organum taken from a book by Caspar Schott, which deal with chronology and astronomy. A photograph of the Organum indicates that this tool consists of a set of tables glued on wooden or cardboard, but details of its contents and applications remain pretty obscure for the reader - a few elaborated examples would have been helpful. The second paper deals with the life of Christoph Scheiner SJ, the co-discoverer of sunspots (next to Galileo), after leaving Rome in 1633 - the year of the Galileo trial. Scheiner spent his later years in the Austrian and

  19. An α-smooth muscle actin (acta2/αsma) zebrafish transgenic line marking vascular mural cells and visceral smooth muscle cells.

    PubMed

    Whitesell, Thomas R; Kennedy, Regan M; Carter, Alyson D; Rollins, Evvi-Lynn; Georgijevic, Sonja; Santoro, Massimo M; Childs, Sarah J

    2014-01-01

    Mural cells of the vascular system include vascular smooth muscle cells (SMCs) and pericytes whose role is to stabilize and/or provide contractility to blood vessels. One of the earliest markers of mural cell development in vertebrates is α smooth muscle actin (acta2; αsma), which is expressed by pericytes and SMCs. In vivo models of vascular mural cell development in zebrafish are currently lacking, therefore we developed two transgenic zebrafish lines driving expression of GFP or mCherry in acta2-expressing cells. These transgenic fish were used to trace the live development of mural cells in embryonic and larval transgenic zebrafish. acta2:EGFP transgenic animals show expression that largely mirrors native acta2 expression, with early pan-muscle expression starting at 24 hpf in the heart muscle, followed by skeletal and visceral muscle. At 3.5 dpf, expression in the bulbus arteriosus and ventral aorta marks the first expression in vascular smooth muscle. Over the next 10 days of development, the number of acta2:EGFP positive cells and the number of types of blood vessels associated with mural cells increases. Interestingly, the mural cells are not motile and remain in the same position once they express the acta2:EGFP transgene. Taken together, our data suggests that zebrafish mural cells develop relatively late, and have little mobility once they associate with vessels.

  20. Association of a Novel ACTA1 Mutation With a Dominant Progressive Scapuloperoneal Myopathy in an Extended Family

    PubMed Central

    Zukosky, Kristen; Meilleur, Katherine; Traynor, Bryan J.; Dastgir, Jahannaz; Medne, Livija; Devoto, Marcella; Collins, James; Rooney, Jachinta; Zou, Yaqun; Yang, Michele L.; Gibbs, J. Raphael; Meier, Markus; Stetefeld, Joerg; Finkel, Richard S.; Schessl, Joachim; Elman, Lauren; Felice, Kevin; Ferguson, Toby A.; Ceyhan-Birsoy, Ozge; Beggs, Alan H.; Tennekoon, Gihan; Johnson, Janel O.; Bönnemann, Carsten G.

    2015-01-01

    IMPORTANCE New genomic strategies can now be applied to identify a diagnosis in patients and families with previously undiagnosed rare genetic conditions. The large family evaluated in the present study was described in 1966 and now expands the phenotype of a known neuromuscular gene. OBJECTIVE To determine the genetic cause of a slowly progressive, autosomal dominant, scapuloperoneal neuromuscular disorder by using linkage and exome sequencing. DESIGN, SETTING, AND PARTICIPANTS Fourteen affected individuals in a 6-generation family with a progressive scapuloperoneal disorder were evaluated. Participants were examined at pediatric, neuromuscular, and research clinics from March 1, 2005, to May 31, 2014. Exome and linkage were performed in genetics laboratories of research institutions. MAIN OUTCOMES AND MEASURES Examination and evaluation by magnetic resonance imaging, ultrasonography, electrodiagnostic studies, and muscle biopsies (n = 3). Genetic analysis included linkage analysis (n = 17) with exome sequencing (n = 7). RESULTS Clinical findings included progressive muscle weakness in an initially scapuloperoneal and distal distribution, including wrist extensor weakness, finger and foot drop, scapular winging, mild facial weakness, Achilles tendon contractures, and diminished or absent deep tendon reflexes. Both age at onset and progression of the disease showed clinical variability within the family. Muscle biopsy specimens demonstrated type I fiber atrophy and trabeculated fibers without nemaline rods. Analysis of exome sequences within the linkage region (4.8 megabases) revealed missense mutation c.591C>A p.Glu197Asp in a highly conserved residue in exon 4 of ACTA1. The mutation cosegregated with disease in all tested individuals and was not present in unaffected individuals. CONCLUSIONS AND RELEVANCE This family defines a new scapuloperoneal phenotype associated with an ACTA1 mutation. A highly conserved protein, ACTA1 is implicated in multiple muscle

  1. Book Review: Beitraege zur Astronomiegeschichte, Band 5 (Acta Historica Astronomiae Vol. 15)

    NASA Astrophysics Data System (ADS)

    Duerbeck, H. W.; Dick, W. R.; Hamel, J.

    2002-12-01

    The 15th volume of the Acta Historica Astronomiae is at the same time the fifth collection of essays on the history of astronomy (Beitraege zur Astronomiegeschichte, Band 5), edited by the historians of astronomy W.R. Dick (Potsdam) and J. Hamel (Berlin). Besides a few short notices and book reviews, the book contains 11 major articles, which deal with astronomical topics covering the time from the 16th to the 20th centuries. The first article, on the analysis and interpretation of historical horoscopes as a source of the history of science, is based on the inaugural lecture of its author, Guenther Oestmann. After a general introduction, which deals with the principles of horoscope making, the author discusses the horoscope of Count Heinrich Ranzau (1526-1598), the Danish governor of Schleswig-Holstein, who was a friend of Tycho Brahe. Oestmann shows that the astronomical-mathematical basis of such a horoscope can be reconstructed and interpreted. However, it is hardly possible to gain an insight in the process how the interpretation of a horoscope was done in detail. The second and third articles, by Franz Daxecker, deal with Athanasius Kircher and Christoph Scheiner, two catholic astronomers of the 17th century. Kircher's Organum Mathematicum is a calculating device that can be used in the fields of arithmetic, geometry, chronology, astronomy, astrology and others. The author provides extracts of the description of the Organum taken from a book by Caspar Schott, which deal with chronology and astronomy. A photograph of the Organum indicates that this tool consists of a set of tables glued on wooden or cardboard, but details of its contents and applications remain pretty obscure for the reader - a few elaborated examples would have been helpful. The second paper deals with the life of Christoph Scheiner SJ, the co-discoverer of sunspots (next to Galileo), after leaving Rome in 1633 - the year of the Galileo trial. Scheiner spent his later years in the Austrian and

  2. Systematic mutational analysis of the amino-terminal domain of the Listeria monocytogenes ActA protein reveals novel functions in actin-based motility.

    PubMed

    Lauer, P; Theriot, J A; Skoble, J; Welch, M D; Portnoy, D A

    2001-12-01

    The Listeria monocytogenes ActA protein acts as a scaffold to assemble and activate host cell actin cytoskeletal factors at the bacterial surface, resulting in directional actin polymerization and propulsion of the bacterium through the cytoplasm. We have constructed 20 clustered charged-to-alanine mutations in the NH2-terminal domain of ActA and replaced the endogenous actA gene with these molecular variants. These 20 clones were evaluated in several biological assays for phenotypes associated with particular amino acid changes. Additionally, each protein variant was purified and tested for stimulation of the Arp2/3 complex, and a subset was tested for actin monomer binding. These specific mutations refined the two regions involved in Arp2/3 activation and suggest that the actin-binding sequence of ActA spans 40 amino acids. We also identified a 'motility rate and cloud-to-tail transition' region in which nine contiguous mutations spanning amino acids 165-260 caused motility rate defects and changed the ratio of intracellular bacteria associated with actin clouds and comet tails without affecting Arp2/3 activation. Several unusual motility phenotypes were associated with amino acid changes in this region, including altered paths through the cytoplasm, discontinuous actin tails in host cells and the tendency to 'skid' or dramatically change direction while moving. These unusual phenotypes illustrate the complexity of ActA functions that control the actin-based motility of L. monocytogenes.

  3. Systematic mutational analysis of the amino-terminal domain of the Listeria monocytogenes ActA protein reveals novel functions in actin-based motility.

    PubMed

    Lauer, P; Theriot, J A; Skoble, J; Welch, M D; Portnoy, D A

    2001-12-01

    The Listeria monocytogenes ActA protein acts as a scaffold to assemble and activate host cell actin cytoskeletal factors at the bacterial surface, resulting in directional actin polymerization and propulsion of the bacterium through the cytoplasm. We have constructed 20 clustered charged-to-alanine mutations in the NH2-terminal domain of ActA and replaced the endogenous actA gene with these molecular variants. These 20 clones were evaluated in several biological assays for phenotypes associated with particular amino acid changes. Additionally, each protein variant was purified and tested for stimulation of the Arp2/3 complex, and a subset was tested for actin monomer binding. These specific mutations refined the two regions involved in Arp2/3 activation and suggest that the actin-binding sequence of ActA spans 40 amino acids. We also identified a 'motility rate and cloud-to-tail transition' region in which nine contiguous mutations spanning amino acids 165-260 caused motility rate defects and changed the ratio of intracellular bacteria associated with actin clouds and comet tails without affecting Arp2/3 activation. Several unusual motility phenotypes were associated with amino acid changes in this region, including altered paths through the cytoplasm, discontinuous actin tails in host cells and the tendency to 'skid' or dramatically change direction while moving. These unusual phenotypes illustrate the complexity of ActA functions that control the actin-based motility of L. monocytogenes. PMID:11886549

  4. Electrostatic and Hydrophobic Interactions Mediate Single-Stranded DNA Recognition and Acta2 Repression by Purine-Rich Element-Binding Protein B.

    PubMed

    Rumora, Amy E; Ferris, Lauren A; Wheeler, Tamar R; Kelm, Robert J

    2016-05-17

    Myofibroblast differentiation is characterized by an increased level of expression of cytoskeletal smooth muscle α-actin. In human and murine fibroblasts, the gene encoding smooth muscle α-actin (Acta2) is tightly regulated by a network of transcription factors that either activate or repress the 5' promoter-enhancer in response to environmental cues signaling tissue repair and remodeling. Purine-rich element-binding protein B (Purβ) suppresses the expression of Acta2 by cooperatively interacting with the sense strand of a 5' polypurine sequence containing an inverted MCAT cis element required for gene activation. In this study, we evaluated the chemical basis of nucleoprotein complex formation between the Purβ repressor and the purine-rich strand of the MCAT element in the mouse Acta2 promoter. Quantitative single-stranded DNA (ssDNA) binding assays conducted in the presence of increasing concentrations of monovalent salt or anionic detergent suggested that the assembly of a high-affinity nucleoprotein complex is driven by a combination of electrostatic and hydrophobic interactions. Consistent with the results of pH titration analysis, site-directed mutagenesis revealed several basic amino acid residues in the intermolecular (R267) and intramolecular (K82 and R159) subdomains that are essential for Purβ transcriptional repressor function in Acta2 promoter-reporter assays. In keeping with their diminished Acta2 repressor activity in fibroblasts, purified Purβ variants containing an R267A mutation exhibited reduced binding affinity for purine-rich ssDNA. Moreover, certain double and triple-point mutants were also defective in binding to the Acta2 corepressor protein, Y-box-binding protein 1. Collectively, these findings establish the repertoire of noncovalent interactions that account for the unique structural and functional properties of Purβ. PMID:27064749

  5. Twenty years of society of medical informatics of b&h and the journal acta informatica medica.

    PubMed

    Masic, Izet

    2012-03-01

    In 2012, Health/Medical informatics profession celebrates five jubilees in Bosnia and Herzegovina: a) Thirty five years from the introduction of the first automatic manipulation of data; b) Twenty five years from establishing Society for Medical Informatics BiH; c) Twenty years from establishing scientific and professional journal of the Society for Medical Informatics of Bosnia and Herzegovina "Acta Informatica Medica"; d) Twenty years from establishing first Cathdra for Medical Informatics on biomedical faculties in Bosnia and Herzegovina and e) Ten years from the introduction of "Distance learning" in medical curriculum. All of the five mentioned activities in the area of Medical informatics had special importance and gave appropriate contribution in the development of Health/Medical informatics in Bosnia And Herzegovina.

  6. Twenty Years of Society of Medical Informatics of B&H and the Journal Acta Informatica Medica

    PubMed Central

    Masic, Izet

    2012-01-01

    In 2012, Health/Medical informatics profession celebrates five jubilees in Bosnia and Herzegovina: a) Thirty five years from the introduction of the first automatic manipulation of data; b) Twenty five years from establishing Society for Medical Informatics BiH; c) Twenty years from establishing scientific and professional journal of the Society for Medical Informatics of Bosnia and Herzegovina „Acta Informatica Medica“; d) Twenty years from establishing first Cathdra for Medical Informatics on biomedical faculties in Bosnia and Herzegovina and e) Ten years from the introduction of “Distance learning” in medical curriculum. All of the five mentioned activities in the area of Medical informatics had special importance and gave appropriate contribution in the development of Health/Medical informatics in Bosnia And Herzegovina. PMID:23322947

  7. Association of histone acetylation at the ACTA2 promoter region with epithelial mesenchymal transition of lens epithelial cells

    PubMed Central

    Ganatra, D A; Rajkumar, S; Patel, A R; Gajjar, D U; Johar, K; Arora, A I; Kayastha, F B; Vasavada, A R

    2015-01-01

    Purpose Epithelial mesenchymal transition (EMT) plays a central role in the development of fibrotic complications of the lens. The current study is designed to check whether EMT of lens epithelial cells (LECs) is regulated by epigenetic modifications and to evaluate the effect of Trichostatin-A (TSA) on the transforming growth factor-β (TGF-β)-induced EMT. Methods Fetal human LECs (FHL124) were treated with TGF-β2 in the presence or absence of TSA. Levels of mRNA, protein, as well as localization of α-smooth muscle actin (αSMA) were studied along with migration of LECs. Acetylation of histone H4 was analyzed and chromatin immunoprecipitation (ChIP) was carried out to study the level of acetylated histone H4 at the promoter of αSMA gene (ACTA2). Student's t-test was used for statistical analysis. Results TGF-β2 treatment resulted in myofibroblast-like changes and increased migratory capacity of FHL124. Protein and mRNA expression of αSMA increased, and immunofluorescence revealed presence of extensive stress fibers. TSA treatment preserved epithelial morphology, retarded cell migration, and abrogated an increase in αSMA levels. TSA led to the accumulation of acetylated histone H4 that was reduced on TGF-β2 treatment. However, increased level of histone H4 acetylation was found at the ACTA2 promoter region during TGF-β treatment. Conclusions The increased level of αSMA, a hallmark of EMT in LECs, is associated with increased level of histone H4 acetylation at its promoter region, and TSA helps in suppressing EMT by epigenetically reducing this level. TSA thus shows promising potential in management of fibrotic conditions of the lens. PMID:25853442

  8. Streptomyces rochei ACTA1551, an Indigenous Greek Isolate Studied as a Potential Biocontrol Agent against Fusarium oxysporum f.sp. lycopersici

    PubMed Central

    Kanini, Grammatiki S.; Katsifas, Efstathios A.; Savvides, Alexandros L.; Karagouni, Amalia D.

    2013-01-01

    Many studies have shown that several Greek ecosystems inhabit very interesting bacteria with biotechnological properties. Therefore Streptomyces isolates from diverse Greek habitats were selected for their antifungal activity against the common phytopathogenic fungus Fusarium oxysporum. The isolate encoded ACTA1551, member of Streptomyces genus, could strongly suppress the fungal growth when examined in antagonistic bioassays in vitro. The isolate was found phylogenetically relative to Streptomyces rochei after analyzing its 16S rDNA sequence. The influence of different environmental conditions, such as medium composition, temperature, and pH on the expression of the antifungal activity was thoroughly examined. Streptomyces rochei ACTA1551 was able to protect tomato seeds from F. oxysporum infection in vivo while it was shown to promote the growth of tomato plants when the pathogen was absent. In an initial effort towards the elucidation of the biochemical and physiological nature of ACTA1551 antifungal activity, extracts from solid streptomycete cultures under antagonistic or/and not antagonistic conditions were concentrated and fractionated. The metabolites involved in the antagonistic action of the isolate showed to be more than one and produced independently of the presence of the pathogen. The above observations could support the application of Streptomyces rochei ACTA1551 as biocontrol agent against F. oxysporum. PMID:23762841

  9. Drosophila indirect flight muscle specific Act88F actin mutants as a model system for studying congenital myopathies of the human ACTA1 skeletal muscle actin gene.

    PubMed

    Haigh, Sarah E; Salvi, Sheetal S; Sevdali, Maria; Stark, Meg; Goulding, David; Clayton, Jonathan D; Bullard, Belinda; Sparrow, John C; Nongthomba, Upendra

    2010-06-01

    Most human ACTA1 skeletal actin gene mutations cause dominant, congenital myopathies often with severely reduced muscle function and neonatal mortality. High sequence conservation of actin means many mutated ACTA1 residues are identical to those in the DrosophilaAct88F, an indirect flight muscle specific sarcomeric actin. Four known Act88F mutations occur at the same actin residues mutated in ten ACTA1 nemaline mutations, A138D/P, R256H/L, G268C/D/R/S and R372C/S. These Act88F mutants were examined for similar muscle phenotypes. Mutant homozygotes show phenotypes ranging from a lack of myofibrils to almost normal sarcomeres at eclosion. Aberrant Z-disc-like structures and serial Z-disc arrays, 'zebra bodies', are observed in homozygotes and heterozygotes of all four Act88F mutants. These electron-dense structures show homologies to human nemaline bodies/rods, but are much smaller than those typically found in the human myopathy. We conclude that the Drosophila indirect flight muscles provide a good model system for studying ACTA1 mutations. PMID:20452215

  10. Treatment with ActRIIB-mFc Produces Myofiber Growth and Improves Lifespan in the Acta1 H40Y Murine Model of Nemaline Myopathy.

    PubMed

    Tinklenberg, Jennifer; Meng, Hui; Yang, Lin; Liu, Fujun; Hoffmann, Raymond G; Dasgupta, Mahua; Allen, Kenneth P; Beggs, Alan H; Hardeman, Edna C; Pearsall, R Scott; Fitts, Robert H; Lawlor, Michael W

    2016-06-01

    Nemaline myopathies (NMs) are a group of congenital muscle diseases caused by mutations in at least 10 genes and associated with a range of clinical symptoms. NM is defined on muscle biopsy by the presence of cytoplasmic rod-like structures (nemaline rods) composed of cytoskeletal material. Myofiber smallness is also found in many cases of NM and may represent a cause of weakness that can be counteracted by treatment. We have used i.p. injection of activin type IIB receptor (ActRIIB)-mFc (an inhibitor of myostatin signaling) to promote hypertrophy and increase strength in our prior murine work; we therefore tested whether ActRIIB-mFc could improve weakness in NM mice through myofiber hypertrophy. We report a study of ActRIIB-mFc treatment in the Acta1 H40Y mouse model of NM. Treatment of Acta1 H40Y mice produced significant increases in body mass, muscle mass, quadriceps myofiber size, and survival, but other measurements of strength (forelimb grip strength, ex vivo measurements of contractile function) did not improve. Our studies also identified that the complications of urethral obstruction are associated with mortality in male hemizygote Acta1 H40Y mice. The incidence of urethral obstruction and histologic evidence of chronic obstruction (inflammation) were significantly lower in Acta1 H40Y mice that had been treated with ActRIIB-mFc. ActRIIB-mFc treatment produces a mild benefit to the disease phenotype in Acta1 H40Y mice. PMID:27102768

  11. Comment on “Chen et al., Fabrication and photovoltaic conversion enhancement…”, Electrochimica Acta, 2014

    NASA Astrophysics Data System (ADS)

    Valentic, Lara; Gorji, Nima E.

    2015-09-01

    In a recent article, Chen et al. [Electrochimica Acta, 2014, 130: 279] presented their fabrication and characterization results on a graphene/n-Si solar cell where the Au nanoparticles were inserted in graphene to increase its optical and electrical properties. The higher efficiency of the device was attributed to increased conductivity of graphene after doping with Au nanoparticles. However, the knowledge in the field of Schottky diode solar cells relates this to increased band bending at the junction. Also, to explain the instability behaviour, they concluded that the growth of silicon oxide on the Si surface or oxygen adsorption on the window layer resulted in the device performance increasing initially and decreasing in the end. However, this instability seems to be due to variation in series resistance reduced at the beginning because of slightly lowered Fermi level and increased at the end by the self-compensation by deep in-diffusion of Au nanoparticles into n-Si layer. We also propose that inserting a very thin p-type layer at the junction will enhance the carrier collection and performance of this device.

  12. A novel ACTA1 mutation resulting in a severe congenital myopathy with nemaline bodies, intranuclear rods and type I fibre predominance.

    PubMed

    Ravenscroft, Gianina; Wilmshurst, Jo M; Pillay, Komala; Sivadorai, Padma; Wallefeld, William; Nowak, Kristen J; Laing, Nigel G

    2011-01-01

    We describe a severe congenital myopathy patient of Xhosa native African origin with a novel de novo p.Gly152Ala skeletal muscle α-actin gene (ACTA1) mutation, who died at 6 months of age. The muscle pathology demonstrated abundant cytoplasmic and intranuclear rods, core-like areas and the unusual feature of larger type I than type II fibres. Our results further expand the phenotypes associated with ACTA1 mutations and provide support for the hypothesis that the structural abnormalities seen are a pathological continuum dependent on the precise mutation and biopsy location. Our results also demonstrate the likely world-wide distribution of de novo mutations in this gene. PMID:20850316

  13. Vascular disease-causing mutation R258C in ACTA2 disrupts actin dynamics and interaction with myosin

    PubMed Central

    Lu, Hailong; Fagnant, Patricia M.; Bookwalter, Carol S.; Joel, Peteranne; Trybus, Kathleen M.

    2015-01-01

    Point mutations in vascular smooth muscle α-actin (SM α-actin), encoded by the gene ACTA2, are the most prevalent cause of familial thoracic aortic aneurysms and dissections (TAAD). Here, we provide the first molecular characterization, to our knowledge, of the effect of the R258C mutation in SM α-actin, expressed with the baculovirus system. Smooth muscles are unique in that force generation requires both interaction of stable actin filaments with myosin and polymerization of actin in the subcortical region. Both aspects of R258C function therefore need investigation. Total internal reflection fluorescence (TIRF) microscopy was used to quantify the growth of single actin filaments as a function of time. R258C filaments are less stable than WT and more susceptible to severing by cofilin. Smooth muscle tropomyosin offers little protection from cofilin cleavage, unlike its effect on WT actin. Unexpectedly, profilin binds tighter to the R258C monomer, which will increase the pool of globular actin (G-actin). In an in vitro motility assay, smooth muscle myosin moves R258C filaments more slowly than WT, and the slowing is exacerbated by smooth muscle tropomyosin. Under loaded conditions, small ensembles of myosin are unable to produce force on R258C actin-tropomyosin filaments, suggesting that tropomyosin occupies an inhibitory position on actin. Many of the observed defects cannot be explained by a direct interaction with the mutated residue, and thus the mutation allosterically affects multiple regions of the monomer. Our results align with the hypothesis that defective contractile function contributes to the pathogenesis of TAAD. PMID:26153420

  14. Advances in membrane protein crystallography: in situ and in meso data collection

    SciTech Connect

    Weyand, Simone; Tate, Christopher G.

    2015-05-23

    Membrane protein structural biology has made tremendous advances over the last decade but there are still many challenges associated with crystallization, data collection and structure determination. Two independent groups, Axford et al. [(2015), Acta Cryst. D71, 1228–1237] and Huang et al. [(2015), Acta Cryst. D71, 1238–1256], have published methods that make a major contribution to addressing these challenges.

  15. Host cell heparan sulfate proteoglycans mediate attachment and entry of Listeria monocytogenes, and the listerial surface protein ActA is involved in heparan sulfate receptor recognition.

    PubMed

    Alvarez-Domínguez, C; Vázquez-Boland, J A; Carrasco-Marín, E; López-Mato, P; Leyva-Cobián, F

    1997-01-01

    The mechanisms by which the intracellular pathogen Listeria monocytogenes interacts with the host cell surface remain largely unknown. In this study, we investigated the role of heparan sulfate proteoglycans (HSPG) in listerial infection. Pretreatment of bacteria with heparin or heparan sulfate (HS), but not with other glycosaminoglycans, inhibited attachment and subsequent uptake by IC-21 murine macrophages and CHO epithelial-like cells. Specific removal of HS from target cells with heparinase III significantly impaired listerial adhesion and invasion. Mutant CHO cells deficient in HS synthesis bound and internalized significantly fewer bacteria than wild-type cells did. Pretreatment of target cells with the HS-binding proteins fibronectin and platelet factor 4, or with heparinase III, impaired listerial infectivity only in those cells expressing HS. Moreover, a synthetic peptide corresponding to the HS-binding ligand in Plasmodium falciparum circumsporozoite protein (pepPf1) inhibited listerial attachment to IC-21 and CHO cells. A motif very similar to the HS-binding site of pepPf1 was found in the N-terminal region of ActA, the L. monocytogenes surface protein responsible for actin-based bacterial motility and cell-to-cell spread. In the same region of ActA, several clusters of positively charged amino acids which could function as HS-binding domains were identified. An ActA-deficient mutant was significantly impaired in attachment and entry due to altered HS recognition functions. This work shows that specific interaction with an HSPG receptor present on the surface of both professional and nonprofessional phagocytes is involved in L. monocytogenes cytoadhesion and invasion and strongly suggests that the bacterial surface protein ActA may be a ligand mediating HSPG receptor recognition. PMID:8975895

  16. Listeria monocytogenes in the Chinese food system: strain characterization through partial actA sequencing and tissue-culture pathogenicity assays.

    PubMed

    Zhou, Xiaohui; Jiao, Xinan; Wiedmann, Martin

    2005-03-01

    Human listeriosis is generally caused by consumption of ready-to-eat (RTE) foods that are stored for extended periods of time at refrigeration temperatures and that permit the growth of the causative agent, Listeria monocytogenes. Food-consumption patterns in China are undergoing rapid changes and more regular consumption of refrigerated-storage RTE foods may increase the risk of human listeriosis. In total, 40 L. monocytogenes isolates were obtained from food (n=32) and sewage (n=6) samples and from two human listeriosis cases that occurred in China. All isolates were characterized into molecular subtypes by DNA sequencing of the 597 bp 3'-terminal region of the virulence gene actA. Sequence data were used to classify the 40 Chinese L. monocytogenes isolates into sequence types and phylogenetic lineages, and to compare the sequence types of the Chinese isolates with those of isolates from the USA. Phylogenetic analyses showed that the Chinese isolates could be separated into two genetic lineages, with 14 and 26 isolates belonging to lineages I and II, respectively. Lineage II could be subdivided further into two clusters, IIA and IIB. Lineages I and II were identical to the two lineages described previously among US L. monocytogenes isolates. In total, 14 actA sequence types could be differentiated among the 40 Chinese L. monocytogenes isolates; two specific actA sequence types were found among both Chinese and US isolates. Isolates belonging to lineage II showed a significantly lower ability to invade and multiply within human intestinal epithelial Caco-2 cells than lineage I isolates. It was concluded that DNA sequencing of the 3'-terminal region of actA appears to be an effective method for rapid subtype and lineage classification of L. monocytogenes. As strains belonging to lineages I and II have previously been found among isolates from Europe and North America, these results show that L. monocytogenes clonal groups found in China are very similar to those

  17. BOOK REVIEW: Astronomie von Olbers bis Schwarzschild. Nationale Entwicklungen und internationale Beziehungen im 19. Jahrhundert (Acta Historica Astronomiae Vol. 16)

    NASA Astrophysics Data System (ADS)

    Sterken, C.; Dick, W. R.; Hamel, J.

    2002-12-01

    The 14th volume of the Acta Historica Astronomiae is the Proceedings of a Colloquium International Relationships in Astronomy (in German) organised by the History of Astronomy Section of the Astronomische Gesellschaft held on September 18 in Lilienthal, Germany. The book contains 13 articles on astronomical topics covering the 19th and 20th centuries. The first paper is by Guenther Oestmann and deals with contemporary assessments of Johann Hieronymus Schroeter's (1745-1816) astronomical works and with later judgements of the scientific importance and significance of his observations as seen by astronomers and historians. This report is complemented by a second article on Schroeter's 25-ft reflector in Lilienthal near Bremen. To this end, author Felix Luehning has constructed a scale model of the telescope, and shows how the building of a model brings a deeper understanding of function and handling of this instrument. This brings us to a third paper on telescope building in Lilienthal: Hans-Joachim Leue describes the cooperation of Johann Hieronymus Schroeter and Johann Gottlieb Schrader in developing a white reflecting metal alloy for use as telescope mirror. The fourth article, by Klaus Schillinger, describes on the basis of archival documents the aquisition history of the Herschel telescopes, including telescope quality check, repair and building. Memorial sites referring to Wilhelm Olbers, Johann Hieronymus Schroeter, Friedrich Wilhelm Bessel and Carl Friedrich Gauss are described by Arno Langkavel in two walks outlined in the very last paper of this book. Peter Brosche, in the fifth paper, discusses the rediscovery of Ceres in December1801, a discovery that was the result of the combined efforts of a theoretician (Gauss) and an observer (Zach). Juergen Hamel's paper is based on previously unused archival sources and discusses the outstanding role played by H. C. Schumacher (1780-1850, editor of the Astronomische Nachrichten) in the communication between

  18. Nemaline myopathy-related skeletal muscle α-actin (ACTA1) mutation, Asp286Gly, prevents proper strong myosin binding and triggers muscle weakness.

    PubMed

    Ochala, Julien; Ravenscroft, Gianina; Laing, Nigel G; Nowak, Kristen J

    2012-01-01

    Many mutations in the skeletal muscle α-actin gene (ACTA1) lead to muscle weakness and nemaline myopathy. Despite increasing clinical and scientific interest, the molecular and cellular pathogenesis of weakness remains unclear. Therefore, in the present study, we aimed at unraveling these mechanisms using muscles from a transgenic mouse model of nemaline myopathy expressing the ACTA1 Asp286Gly mutation. We recorded and analyzed the mechanics of membrane-permeabilized single muscle fibers. We also performed molecular energy state computations in the presence or absence of Asp286Gly. Results demonstrated that during contraction, the Asp286Gly acts as a "poison-protein" and according to the computational analysis it modifies the actin-actin interface. This phenomenon is likely to prevent proper myosin cross-bridge binding, limiting the fraction of actomyosin interactions in the strong binding state. At the cell level, this decreases the force-generating capacity, and, overall, induces muscle weakness. To counterbalance such negative events, future potential therapeutic strategies may focus on the inappropriate actin-actin interface or myosin binding. PMID:23029319

  19. Multimodal MRI and (31)P-MRS investigations of the ACTA1(Asp286Gly) mouse model of nemaline myopathy provide evidence of impaired in vivo muscle function, altered muscle structure and disturbed energy metabolism.

    PubMed

    Gineste, Charlotte; Duhamel, Guillaume; Le Fur, Yann; Vilmen, Christophe; Cozzone, Patrick J; Nowak, Kristen J; Bendahan, David; Gondin, Julien

    2013-01-01

    Nemaline myopathy (NM), the most common non-dystrophic congenital disease of skeletal muscle, can be caused by mutations in the skeletal muscle α-actin gene (ACTA1) (~25% of all NM cases and up to 50% of severe forms of NM). Muscle function of the recently generated transgenic mouse model carrying the human Asp286Gly mutation in the ACTA1 gene (Tg(ACTA1)(Asp286Gly)) has been mainly investigated in vitro. Therefore, we aimed at providing a comprehensive picture of the in vivo hindlimb muscle function of Tg(ACTA1)(Asp286Gly) mice by combining strictly noninvasive investigations. Skeletal muscle anatomy (hindlimb muscles, intramuscular fat volumes) and microstructure were studied using multimodal magnetic resonance imaging (Dixon, T2, Diffusion Tensor Imaging [DTI]). Energy metabolism was studied using 31-phosphorus Magnetic Resonance Spectroscopy ((31)P-MRS). Skeletal muscle contractile performance was investigated while applying a force-frequency protocol (1-150 Hz) and a fatigue protocol (6 min-1.7 Hz). Tg(ACTA1)(Asp286Gly) mice showed a mild muscle weakness as illustrated by the reduction of both absolute (30%) and specific (15%) maximal force production. Dixon MRI did not show discernable fatty infiltration in Tg(ACTA1)(Asp286Gly) mice indicating that this mouse model does not reproduce human MRI findings. Increased T2 values were observed in Tg(ACTA1)(Asp286Gly) mice and might reflect the occurrence of muscle degeneration/regeneration process. Interestingly, T2 values were linearly related to muscle weakness. DTI experiments indicated lower λ2 and λ3 values in Tg(ACTA1)(Asp286Gly) mice, which might be associated to muscle atrophy and/or the presence of histological anomalies. Finally (31)P-MRS investigations illustrated an increased anaerobic energy cost of contraction in Tg(ACTA1)(Asp286Gly) mice, which might be ascribed to contractile and non-contractile processes. Overall, we provide a unique set of information about the anatomic, metabolic and functional

  20. EDM-DEDM and protein crystal structure solution.

    PubMed

    Caliandro, Rocco; Carrozzini, Benedetta; Cascarano, Giovanni Luca; Giacovazzo, Carmelo; Mazzone, Anna Maria; Siliqi, Dritan

    2009-05-01

    Electron-density modification (EDM) procedures are the classical tool for driving model phases closer to those of the target structure. They are often combined with automated model-building programs to provide a correct protein model. The task is not always performed, mostly because of the large initial phase error. A recently proposed procedure combined EDM with DEDM (difference electron-density modification); the method was applied to the refinement of phases obtained by molecular replacement, ab initio or SAD phasing [Caliandro, Carrozzini, Cascarano, Giacovazzo, Mazzone & Siliqi (2009), Acta Cryst. D65, 249-256] and was more effective in improving phases than EDM alone. In this paper, a novel fully automated protocol for protein structure refinement based on the iterative application of automated model-building programs combined with the additional power derived from the EDM-DEDM algorithm is presented. The cyclic procedure was successfully tested on challenging cases for which all other approaches had failed.

  1. 2-(5-Iodo-2-oxoindolin-3-yl­idene)hydrazinecarbo­thio­amide including an unknown solvate

    PubMed Central

    Conceição Duarte de Bittencourt, Viviane; Carratu Gervini, Vanessa; Rosa de Menezes Vicenti, Juliano; Maciel Velasques, Jecika; Jussiane Zambiazi, Priscilla

    2014-01-01

    The mol­ecule of the title compound, C9H7IN4OS, is almost planar (r.m.s. deviation = 0.0373 Å). In the mol­ecule, N—H⋯N and N—H⋯O hydrogen bonds generate, respectively, S(5) and S(6) ring motifs. In the crystal, mol­ecules are linked via N—H⋯O hydrogen bonds, forming chains propagating along [010]. These chains are linked via S⋯I contacts [3.4915 (16) Å], forming sheets lying parallel to (100). A region of disordered electron density, probably a disordered tetra­hydro­furan solvent mol­ecule, was treated using the SQUEEZE routine in PLATON [Spek (2009). Acta Cryst. D65, 148–155]. The formula mass and unit-cell characteristics were not taken into account during refinement. PMID:24940248

  2. 1,3-Alternate conformer 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra-kis-(4-methyl-sulfanylbenz-yloxy)-2,8,14,20-tetra-thia-calix[4]arene.

    PubMed

    Gao, Qingsong; Xie, Dexun; An, Delie

    2013-01-01

    The title thia-calix[4]arene derivative, C72H80O4S8, adopts a 1,3-alternate conformation, where the four 4-methyl-sul-fan-yl-benzyl groups are located alternately at the two sides of a virtual plane defined by the four bridging S atoms. In the crystal, there are no significant inter-molecular inter-actions present. Some of the peripheral tert-butyl and methyl-sulfanyl groups are disordered over two positions. A region of disordered electron density, occupying voids of ca 700 Å(3) for an electron count of 124, was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. PMID:24046595

  3. 1,3,5-Tris(4-meth-oxy-phen-yl)-1,3,5-triazinane-2,4,6-trione.

    PubMed

    Fang, Li; Li, Feifei; Luo, Xuemei

    2014-02-01

    The complete mol-ecule of the title compound, C24H21N3O6, is generated by the application of threefold rotation symmetry about an axis perpendicular to the central ring. The mol-ecule exhibits a propeller-like shape. The dihedral angle between each benzene ring and the heterocyclic ring is 74.0 (1)°. The mol-ecules pack with no specific inter-molecular inter-actions between them. The SQUEEZE procedure in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155] was used to model disordered solvent mol-ecules, presumed to be acetone; the calculated unit-cell data do not take into account the presence of these. PMID:24764847

  4. Bis{μ-cis-1,3-bis-[(di-tert-butyl-phosphan-yl)-oxy]cyclo-hexane-κ(2) P:P'}bis-[carbonylnickel(0)] including an unknown solvent molecule.

    PubMed

    Jonasson, Klara J; Wendt, Ola F

    2014-05-01

    The title compound, [Ni2(C22H46P2O2)2(CO)2], is located about a centre of inversion with the Ni(0) atom within a distorted trigonal-planar geometry. The cyclo-hexyl rings are in the usual chair conformation with the 1,3-cis substituents equatorially oriented. No specific inter-molecular inter-actions are noted in the crystal packing. A region of disordered electron density, most probably a disordered deuterobenzene solvent molecule, was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. Its formula mass and unit-cell characteristics were not taken into account during refinement. PMID:24860309

  5. Diethyl 4-(2-meth-oxy-phen-yl)-2,6-di-methyl-1,4-di-hydro-pyridine-3,5-di-carboxyl-ate.

    PubMed

    Wang, Ke; Wang, Yifeng; Yao, Minjie; Xu, Danqian

    2013-05-01

    In the title compound, C20H25NO5, the di-hydro-pyridine ring adopts a flattened boat conformation. The meth-oxy-phenyl ring is almost perpendicular to the mean plane of the pyridine ring [dihedral angle = 88.42 (3)°]. The two carbonyl units adopt a synperiplanar conformation with respect to the double bonds in the di-hydro-pyridine ring. In the crystal, mol-ecules are connected by N-H⋯O hydrogen bonds into R 4 (4)(24) tetra-meric rings. A region of disordered electron density, located at the center of four adjacent mol-ecules, was treated with the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. It is probably the result of traces of the solvent of crystallization and was not taken into account during the structure refinement. PMID:23723929

  6. 2-(5-Iodo-2-oxoindolin-3-yl-idene)hydrazinecarbo-thio-amide including an unknown solvate.

    PubMed

    Conceição Duarte de Bittencourt, Viviane; Carratu Gervini, Vanessa; Rosa de Menezes Vicenti, Juliano; Maciel Velasques, Jecika; Jussiane Zambiazi, Priscilla

    2014-06-01

    The mol-ecule of the title compound, C9H7IN4OS, is almost planar (r.m.s. deviation = 0.0373 Å). In the mol-ecule, N-H⋯N and N-H⋯O hydrogen bonds generate, respectively, S(5) and S(6) ring motifs. In the crystal, mol-ecules are linked via N-H⋯O hydrogen bonds, forming chains propagating along [010]. These chains are linked via S⋯I contacts [3.4915 (16) Å], forming sheets lying parallel to (100). A region of disordered electron density, probably a disordered tetra-hydro-furan solvent mol-ecule, was treated using the SQUEEZE routine in PLATON [Spek (2009). Acta Cryst. D65, 148-155]. The formula mass and unit-cell characteristics were not taken into account during refinement. PMID:24940248

  7. Bis{2-[(Tri-phenyl-meth-yl)amino]-phen-yl} diselenide aceto-nitrile monosolvate.

    PubMed

    Neuba, Adam; Schneider, Tobias; Flörke, Ulrich; Henkel, Gerald

    2014-05-01

    The mol-ecular structure of the title compound, C50H40N2Se2·C2H3N, shows a syn conformation of the benzene rings bound to the Se atoms, with an Se-Se bond length of 2.3529 (6) Å and a C-Se-Se-C torsion angle of 93.53 (14)°. The two Se-bonded aromatic ring planes make a dihedral angle of 18.42 (16)°. Intra-molecular N-H⋯Se hydrogen bonds are noted. Inter-molecular C-H⋯Se inter-actions give rise to supra-molecular chains extended along [100]. One severely disordered aceto-nitrile solvent mol-ecule per asymmetric unit was treated with SQUEEZE in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]; the crystal data take the presence of this mol-ecule into account. PMID:24860347

  8. 4-Meth-oxy-N-[(4-methyl-phen-yl)sulfon-yl]benzamide including an unknown solvate.

    PubMed

    Sreenivasa, Swamy; Palakshamurthy, Bandrehalli Siddagangaiah; Tonannavar, Jagdish; Jayashree, Yenagi; Sudha, Achar Gurumurthy; Suchetan, Parameshwar Adimoole

    2013-10-19

    In the title compound, C15H15NO4S, the dihedral angle between the benzene rings is 78.62 (16)°. In the crystal, adjacent mol-ecules are linked along the c axis into C(4) chains through strong N-H⋯O hydrogen bonds. Mol-ecules are further connected through C-H⋯O hydrogen bonds into a hexa-meric unit generating an R (6) 6(66) motif. Another C-H⋯O inter-action connects the mol-ecules along the c axis, forming C(5) chains. A region of disordered electron density, most probably disordered methanol-water solvent mol-ecules, was treated with the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. The formula mass and unit-cell characteristics do not take into account this disordered solvent. PMID:24454100

  9. 3,3'-(1-Oxopropane-1,3-di-yl)bis-(1,3-thia-zolidine-2-thione) chloro-benzene hemisolvate.

    PubMed

    Franzel, Christine; Purdy, Andrew; Butcher, Ray J

    2013-03-01

    The title compound, C9H12N2OS4·0.5C6H5Cl, which contains two 1,3-thia-zolidine-2-thione rings, is a by-product of the synthesis of 3-acryloyl-1,3-thia-zolidine-2-thione. The dihedral angle between these rings is 79.95 (9)°, with both rings displaying a twisted conformation. The twist angle of the amide group is 5.6 (1)°. In the crystal, the molecules are linked into [001] chains by C-H⋯O interactions. The chloro-benzene solvent mol-ecule was found to show unresolvable disorder about a centre of inversion and its contribution to the scattering was removed with the SQUEEZE option in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. PMID:23476562

  10. Carbon-yl{3,3'-di-tert-butyl-5,5'-dimeth-oxy-2,2'-bis-[(4,4,5,5-tetra-methyl-1,3,2-dioxaphospho-lan-2-yl)-oxy]biphenyl-κ(2) P,P'}hydrido(triphenyl-phosphane-κP)rhodium(I) diethyl ether tris-olvate.

    PubMed

    Selent, Detlef; Spannenberg, Anke; Börner, Armin

    2013-01-01

    In the title compound, [RhH(C74H68O8P2)(C18H15P)(CO)]·3C4H10O, the CHP3 coordination set at the Rh(I) ion is arranged in a distorted trigonal-bipyramidal geometry with the P atoms adopting equatorial coordination sites and the C atom of the carbonyl ligand as well as the H atom adopting the axial sites. The asymmetric unit contains two very similar mol-ecules of the rhodium complex, two half-occupied diethyl ether mol-ecules and further diethyl ether solvent mol-ecules which could not be modelled successfully. Therefore contributions of the latter were removed from the diffraction data using the SQUEEZE procedure in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. PMID:23476316

  11. 1,3,5-Tri-p-tolyl-pentane-1,5-diol.

    PubMed

    Thiruvalluvar, A; Chithiravel, R; Muthusubramanian, S; Butcher, R J

    2014-02-01

    In the title compound, C26H30O2, the central benzene ring forms dihedral angles of 14.85 (15) and 28.17 (14)° with the terminal benzene rings. The dihedral angle between the terminal benzene rings is 32.14 (13)°. The crystal packing exhibits two strong inter-molecular O-H⋯O hydrogen bonds, forming directed four-membered co-operative rings. A region of disordered electron density, most probably disordered ethyl acetate solvent mol-ecules, occupying voids of ca 519 Å(3) for an electron count of 59, was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. Their formula mass and unit-cell characteristics were not taken into account during refinement. The structure was refined as an inversion twin [absolute structure parameter = -0.3 (4)]. PMID:24764851

  12. (5-Methyl-pyrazine-2-carboxyl-ato-κ(2) N (1),O)bis-[2-(4-methyl-pyridin-2-yl-κN)-3,5-bis-(tri-fluoro-meth-yl)phenyl-κC (1)]iridium(III) chloro-form hemisolvate.

    PubMed

    Kim, Young-Inn; Song, Young-Kwang; Kang, Sung Kwon

    2014-02-01

    In the title complex, [Ir(C14H8F6N)2(C6H5N2O2)]·0.5CHCl3, the Ir(III) atom adopts a distorted octa-hedral geometry, being coordinated by three N atoms (arranged meridionally), two C atoms and one O atom of three bidentate ligands. The complex mol-ecules pack with no specific inter-molecular inter-actions between them. The SQUEEZE procedure in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155] was used to model a disordered chloro-form solvent mol-ecule; the calculated unit-cell data allow for the presence of half of this mol-ecule in the asymmetric unit. PMID:24764808

  13. 1,3,5-Tri-p-tolyl­pentane-1,5-diol

    PubMed Central

    Thiruvalluvar, A.; Chithiravel, R.; Muthusubramanian, S.; Butcher, R. J.

    2014-01-01

    In the title compound, C26H30O2, the central benzene ring forms dihedral angles of 14.85 (15) and 28.17 (14)° with the terminal benzene rings. The dihedral angle between the terminal benzene rings is 32.14 (13)°. The crystal packing exhibits two strong inter­molecular O—H⋯O hydrogen bonds, forming directed four-membered co-operative rings. A region of disordered electron density, most probably disordered ethyl acetate solvent mol­ecules, occupying voids of ca 519 Å3 for an electron count of 59, was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155]. Their formula mass and unit-cell characteristics were not taken into account during refinement. The structure was refined as an inversion twin [absolute structure parameter = −0.3 (4)]. PMID:24764851

  14. A rebuttal to "A comment to 'Normalization of urinary pteridines by urine specific gravity for early cancer detection' [Clin. Chim. Acta 435 (2014) 42-47]".

    PubMed

    Ma, Yinfa; Burton, Casey; Shi, Honglan

    2015-01-01

    We really appreciate the comments from Drs. Reibnegger and Fuchs regarding our recent publication "Normalization of urinary pteridines by urine specific gravity for early cancer detection [Clin. Chim. Acta 435 (2014) 42-47]". In their letter, Drs. Reibnegger and Fuchs identify several potential concerns regarding our recent publication [1] that evaluated the normalization performance of urine specific gravity (USG) and urinary creatinine with respect to the diagnostic properties of selected pteridines in discerning aggressive and benign breast cancers. Their letter not only provides unique insights that are both relevant and helpful to many researchers engaging in similar studies, but also provides a wonderful opportunity for us to address these potential concerns that may also be shared by other readers. We addressed all of the comments by Drs. Reibnegger and Fuchs in this letter.

  15. A neo-clerodane diterpene from Teucrium tomentosum. Corrigendum

    PubMed Central

    Devi, S. Soundarya; Malathi, R.; Rajan, S. S.; Aravind, S.; Krishnakumari, G. N.; Ravikumar, K.

    2009-01-01

    The chemical name of the title compound in the paper by Devi, Malathi, Rajan, Aravind, Krishnakumari & Ravikumar [Acta Cryst. (2004), E60, o117–o119] is corrected and the structural diagram is updated. PMID:21582975

  16. Combined MRI and ³¹P-MRS investigations of the ACTA1(H40Y) mouse model of nemaline myopathy show impaired muscle function and altered energy metabolism.

    PubMed

    Gineste, Charlotte; Le Fur, Yann; Vilmen, Christophe; Le Troter, Arnaud; Pecchi, Emilie; Cozzone, Patrick J; Hardeman, Edna C; Bendahan, David; Gondin, Julien

    2013-01-01

    Nemaline myopathy (NM) is the most common disease entity among non-dystrophic skeletal muscle congenital diseases. Mutations in the skeletal muscle α-actin gene (ACTA1) account for ∼25% of all NM cases and are the most frequent cause of severe forms of NM. So far, the mechanisms underlying muscle weakness in NM patients remain unclear. Additionally, recent Magnetic Resonance Imaging (MRI) studies reported a progressive fatty infiltration of skeletal muscle with a specific muscle involvement in patients with ACTA1 mutations. We investigated strictly noninvasively the gastrocnemius muscle function of a mouse model carrying a mutation in the ACTA1 gene (H40Y). Skeletal muscle anatomy (hindlimb muscles and fat volumes) and energy metabolism were studied using MRI and (31)Phosphorus magnetic resonance spectroscopy. Skeletal muscle contractile performance was investigated while applying a force-frequency protocol (from 1-150 Hz) and a fatigue protocol (80 stimuli at 40 Hz). H40Y mice showed a reduction of both absolute (-40%) and specific (-25%) maximal force production as compared to controls. Interestingly, muscle weakness was associated with an improved resistance to fatigue (+40%) and an increased energy cost. On the contrary, the force frequency relationship was not modified in H40Y mice and the extent of fatty infiltration was minor and not different from the WT group. We concluded that the H40Y mouse model does not reproduce human MRI findings but shows a severe muscle weakness which might be related to an alteration of intrinsic muscular properties. The increased energy cost in H40Y mice might be related to either an impaired mitochondrial function or an alteration at the cross-bridges level. Overall, we provided a unique set of anatomic, metabolic and functional biomarkers that might be relevant for monitoring the progression of NM disease but also for assessing the efficacy of potential therapeutic interventions at a preclinical level. PMID:23613869

  17. Crystal structure of bis-p-anizidinegossypol with an unknown solvate

    PubMed Central

    Honkeldieva, Muhabbat T.; Talipov, Samat A.; Kunafiev, Rishad; Ibragimov, Bakhtiyar T.

    2015-01-01

    The title compound, C44H44N2O8, (systematic name: 1,1′,6,6′-tetra­hydroxy-5,5′-diisopropyl-8,8′-bis­{[(4-meth­oxy­phen­yl)iminium­yl]meth­yl}-3,3′-dimethyl-2,2′-bi­naphthalene-7,7′-diolate) has been obtained by the addition of p-anizidine to gossypol dissolved in di­chloro­methane. In the solid state, the title compound exists in the enamine or quinoid form. The two naphthyl moieties are inclined to one another by 72.08 (5)°. The pendant phenyl rings are inclined at 22.26 (14) and 23.86 (13)° to the corresponding naphthyl rings. In the crystal, mol­ecules are incorporated into layers through inversion-related pairs of O—H⋯O inter­actions [graph sets R 2 2(20) and R 2 2(10)] and translation-related O—H⋯O inter­actions [graph set C(15)]. The packing of these layers in the crystal structure gives rise to channels in the [011] direction, with hydro­phobic inter­actions occurring between adjacent layers. The channels are 5–7 Å wide, and the void volume of each cell is 655 Å3, corresponding to 26.6% of the cell volume. Disordered guest mol­ecules, probably solvent and water mol­ecules, occupy these voids of the crystal; their contribution to the scattering was removed with the SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9–18] of PLATON [Spek (2009 ▸). Acta Cryst. D65, 148–155]. PMID:26870395

  18. Crystal structure of bis-p-anizidinegossypol with an unknown solvate.

    PubMed

    Honkeldieva, Muhabbat T; Talipov, Samat A; Kunafiev, Rishad; Ibragimov, Bakhtiyar T

    2015-12-01

    The title compound, C44H44N2O8, (systematic name: 1,1',6,6'-tetra-hydroxy-5,5'-diisopropyl-8,8'-bis-{[(4-meth-oxy-phen-yl)iminium-yl]meth-yl}-3,3'-dimethyl-2,2'-bi-naphthalene-7,7'-diolate) has been obtained by the addition of p-anizidine to gossypol dissolved in di-chloro-methane. In the solid state, the title compound exists in the enamine or quinoid form. The two naphthyl moieties are inclined to one another by 72.08 (5)°. The pendant phenyl rings are inclined at 22.26 (14) and 23.86 (13)° to the corresponding naphthyl rings. In the crystal, mol-ecules are incorporated into layers through inversion-related pairs of O-H⋯O inter-actions [graph sets R 2 (2)(20) and R 2 (2)(10)] and translation-related O-H⋯O inter-actions [graph set C(15)]. The packing of these layers in the crystal structure gives rise to channels in the [011] direction, with hydro-phobic inter-actions occurring between adjacent layers. The channels are 5-7 Å wide, and the void volume of each cell is 655 Å(3), corresponding to 26.6% of the cell volume. Disordered guest mol-ecules, probably solvent and water mol-ecules, occupy these voids of the crystal; their contribution to the scattering was removed with the SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9-18] of PLATON [Spek (2009 ▸). Acta Cryst. D65, 148-155].

  19. Crystal structure of bis-p-anizidinegossypol with an unknown solvate.

    PubMed

    Honkeldieva, Muhabbat T; Talipov, Samat A; Kunafiev, Rishad; Ibragimov, Bakhtiyar T

    2015-12-01

    The title compound, C44H44N2O8, (systematic name: 1,1',6,6'-tetra-hydroxy-5,5'-diisopropyl-8,8'-bis-{[(4-meth-oxy-phen-yl)iminium-yl]meth-yl}-3,3'-dimethyl-2,2'-bi-naphthalene-7,7'-diolate) has been obtained by the addition of p-anizidine to gossypol dissolved in di-chloro-methane. In the solid state, the title compound exists in the enamine or quinoid form. The two naphthyl moieties are inclined to one another by 72.08 (5)°. The pendant phenyl rings are inclined at 22.26 (14) and 23.86 (13)° to the corresponding naphthyl rings. In the crystal, mol-ecules are incorporated into layers through inversion-related pairs of O-H⋯O inter-actions [graph sets R 2 (2)(20) and R 2 (2)(10)] and translation-related O-H⋯O inter-actions [graph set C(15)]. The packing of these layers in the crystal structure gives rise to channels in the [011] direction, with hydro-phobic inter-actions occurring between adjacent layers. The channels are 5-7 Å wide, and the void volume of each cell is 655 Å(3), corresponding to 26.6% of the cell volume. Disordered guest mol-ecules, probably solvent and water mol-ecules, occupy these voids of the crystal; their contribution to the scattering was removed with the SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9-18] of PLATON [Spek (2009 ▸). Acta Cryst. D65, 148-155]. PMID:26870395

  20. Poly[[di­aqua­[μ-1,4-bis(pyridin-4-ylmeth­yl)piperazine-κ2 N:N′]{μ-2,2′-[(1,4-phenyl­ene)bis(­oxy)]di­acetato-κ2 O:O′}cobalt(II)] penta­hydrate

    PubMed Central

    Sample, Alexander D.; LaDuca, Robert L.

    2014-01-01

    In the title compound, {[Co(C10H8O6)(C16H20N4)(H2O)2]·5H2O}n, octa­hedrally coordinated CoII ions on crystallographic inversion centres are bound by trans O atoms belonging to two hydro­quinone-O,O′-di­acetate (hqda) anions {systematic name: 2,2′-[(1,4-phenyl­ene)bis­(­oxy)]di­acetate}, two trans-pyridine N-donor atoms from two bis­(pyridin-4-ylmeth­yl)piperazine (4-bpmp) ligands, and two trans aqua ligands. The exobidentate hqda and 4-bpmp ligands form [Co(hqda)(4-bpmp)(H2O)2]n coordination polymer layers parallel to (110) that are anchored into the full crystal structure by O—H⋯O hydrogen bonding between aqua ligands and ligated hqda O atoms. Disordered water mol­ecules of crystallization occupy incipient channels along [100]. However, these could not modeled reliably and so they were treated with SQUEEZE in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155]; the crystal data take the presence of these mol­ecules into account. The crystal under investigation was twinned by non-merohedry, the twin fraction of the components being 53.3% and 46.7%. Only data from the major twin component were used in the refinement. PMID:24940193

  1. Dichlorido(3-phenyl-indenyl-idene)bis-(triphenyl-phosphane)ruthenium(II) tetra-hydro-furan disolvate.

    PubMed

    Bats, Jan W; Pérez Gomes, Jessica; Doppiu, Angelino; Hashmi, A Stephen K

    2011-06-01

    The Ru(II) atom in the title compound, [RuCl(2)(C(15)H(10))(C(18)H(15)P)(2)]·2C(4)H(8)O, has a distorted square-pyramidal conformation. The P and Cl atoms are at the base of the pyramid and the Ru-C(indenyl-idene) bond is in the axial position. The two Cl ligands and the two phosphane ligands are in trans positions. The Cl-Ru-Cl and P-Ru-P angles are 157.71 (2) and 166.83 (2)°, respectively. The two independent tetra-hydro-furan (THF) solvent mol-ecules are disordered. One THF mol-ecule was refined using a split-atom model. The second THF mol-ecule was accounted for by using program PLATON/SQUEEZE [Spek (2009 ▶). Acta Cryst. D65, 148-155]. The molecular conformation shows three intramolecular C-H⋯Cl contacts and two C-H⋯π interactions while the crystal packing features an intermolecular C-H⋯Cl contact and two very weak intermolecular C-H⋯π contacts. PMID:21754621

  2. The correct assignment of stereochemistry in di-μ-dichlorido-bis{bis[2-(5-benzylsulfonyl)-3-fluoro-2-(pyridin-2-yl)phenyl-κ2N,C1]iridium(III)} toluene monosolvate.

    PubMed

    Mesto, Ernesto; Scordari, Fernando; Lacalamita, Maria; De Cola, Luisa; Ragni, Roberta; Farinola, Gianluca Maria

    2013-05-01

    The title complex, [Ir2(C18H13FNO2S)4Cl2]·C7H8, was crystallized from dichloromethane solution under a toluene atmosphere. It is a dimeric complex in which each of the two Ir(III) centres is octahedrally coordinated by two bridging chloride ligands and by two chelating cyclometalated 2-(4-benzylsulfonyl-2-fluorophenyl)pyridine ligands. The crystal structure analysis unequivocally establishes the trans disposition of the two cyclometalated ligands bound to each Ir(III) centre, contrary to our previous hypothesis of a cis disposition. The latter was based on the (1)H NMR spectra of a series of dimeric benzylsulfonyl-functionalized dichloride-bridged iridium complexes, including the compound described in the present work [Ragni et al. (2009). Chem. Eur. J. 15, 136-148]. The toluene solvent molecules, embedded in cavities in the crystal structure, are highly disordered and could not be modelled successfully; their contribution was removed from the refinement using the SQUEEZE routine in the program PLATON [Spek (2009). Acta Cryst. D65, 148-155]. PMID:23629895

  3. Poly[di-methyl-ammonium [(μ2-benzene-1,2-di-carboxyl-ato-κ(2) O (1):O (3))[μ2-3-(pyri-din-4-yl)-1H-pyrazol-1-ido-κ(2) N (1):N (3)]cuprate(II)

    PubMed

    Na, Liu

    2013-01-01

    In the title complex, {(C2H8N)[Cu(C8H4O4)(C8H6N3)]} n , there are two Cu(II) cations (each located on a centre of inversion), one benzene-1,2-di-carboxyl-ate dianion, one 3-(pyridin-4-yl)-1H-pyrazol-1-ide anion and one di-methyl-ammonium cation in the asymmetric unit. The di-methyl-ammonium cation was highly disordered and was treated with the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]; the crystallographic data takes into account the presence of the cation. Each Cu(II) cation exhibits a square-planar coordination geometry. A benzene-1,2-di-carboxyl-ate dianion bridges two Cu(II) cations, building a linear chain along [001]. The chains are connected by 3-(pyridin-4-yl)-1H-pyrazol-1-ide anions, constructing a layer parallel to (101). The layers are assembled into a three-dimensional supra-molecular network through C-H⋯π inter-actions. PMID:24046573

  4. 5,10,15,20-Tetra-kis(4-acetyl-oxyphen-yl)porphyrin including an unknown solvate.

    PubMed

    Miranda, Micael D; Ramos Silva, Manuela; Maria, Teresa M R; Balakrishna, Avula; Sobral, Abilio J F N

    2012-12-01

    Mol-ecules of the title compound, C52H38N4O8, are located on an inversion center so that the asymmetric cell contains one half of the mol-ecule. The macrocycle exhibits a ruffled conformation with a maximum deviation of 0.16 Å for the 24 macrocycle atoms: the dihedral angle between adjacent five-membered rings is 5.13 (19)°. The benzene rings are rotated by 70.25 (19)° with respect to their adjacent protonated five-membered rings, and by 65.56 (19)° with respect to the unprotonated rings. The porphyrin conformation is supported by bifurcated N-H⋯(N,N) hydrogen bonds. The structure contained poorly resolved solvent mol-ecules in voids of volume 217 Å(3) per unit cell. The latter were treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. As the solvent could not be identified exactly, it was not included in the calculation of the overall formula weight, density and absorption coefficient. PMID:23476273

  5. 1-[4-({4-[(E)-(2-Hy-droxy-naphthalen-1-yl)methyl-idene-amino]-phen-yl}sulfan-yl)phen-yl]ethanone.

    PubMed

    Hebbachi, Rabihe; Mousser, Hénia; Mousser, Abdelhamid

    2013-01-01

    The title Schiff base compound, C25H19NO2S, crystallizes in a statistically disordered structure comprising keto and enol tautomeric forms. In the enol form, the benzenoid arrangment is promoted by a strong intra-molecular O-H⋯N hydrogen bond and adopts an E conformation about the imine bond. In the keto form there is an intramolecular N-H⋯O hydrogen bond. In the crystal, an extended network of C-H⋯O hydrogen bonds stabilizes columns parallel to the c axis, forming large voids (there are four cavities of 108 Å(3) per unit cell) with highly disordered residual electron density. The SQUEEZE procedure in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155] was used to eliminate the contribution of this electron density from the intensity data, and the solvent-free model was employed for the final refinement. The contribution of this undetermined solvent was ignored in the calculation of the unit-cell characteristics. PMID:23476448

  6. rac-N-Benzyl-isatincreatinine (unknown solvate).

    PubMed

    Penthala, Narsimha Reddy; Crooks, Peter A

    2013-02-01

    The title compound, C(19)H(18)N(4)O(3) [systematic name: (RS)-1-benzyl-3-hy-droxy-3-(2-imino-3-methyl-5-oxoimidazolidin-4-yl)-2,3-dihydro-1H-indol-2-one], was prepared as a racemate (RR and SS) by the aldol condensation of N-benzyl-isatin with creatinine in the presence of sodium acetate in acetic acid. The r.m.s. deviation of the isatin ring system is 0.033 Å. The benzyl group is disordered over two orientations, with refined occupancies of 0.847 (7) and 0.153 (7). The dihedral angles between the isatin ring system and the benzene ring (major disorder component) and the imidazole ring are 82.82 (7) and 51.31 (3)°, respectively, In the crystal, mol-ecules are linked into (001) sheets by N-H⋯O and O-H⋯N hydrogen bonds, which incorporate R(2) (2)(9) ring motifs. The crystal was grown from mixed solvents (ethanol, methanol and possibly also ethyl acetate). These solvents are disordered in the crystal and the resulting electron density was found to be uninter-pretable. The solvent contribution to the scattering was removed with the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. The formula mass and density do not take account of the solvent. PMID:23424560

  7. 3,10,14,21-Tetra-kis(4-meth-oxy-phen-yl)penta-cyclo-[11.8.0.0(2,11).0(4,9).0(15,20)]henicosa-1(21),2,4(9),5,7,10,13,15(20),16,18-decaen-12-one chloro-form monosolvate.

    PubMed

    Gopinath, S; Narayanan, P; Sethusankar, K; Nandakumar, Meganathan; Mohanakrishnan, Arasambattu K

    2014-08-01

    The asymmetric unit of the title compound, C49H36O6·CHCl3, contains half an organic mol-ecule, the complete mol-ecule being generated by the operation of a crystallographic twofold rotation axis, and half a highly disordered chloro-form mol-ecule. The contribution to the diffraction pattern of the latter was removed using the program SQUEEZE in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]; the unit-cell characteristics take into account the presence of CHCl3. The dihedral angles between the planes of the naphthalene ring system and the meth-oxy-benzene rings are 71.05 (7) (syn to the central C=O group) and 57.27 (6)° (anti to the central C=O group). In the crystal, mol-ecules are linked by C-H⋯O inter-actions, generating C(12) chains running parallel to the b axis. PMID:25249919

  8. 1,1'-(Diselanediylbis{[P,P-diphenyl-N-(tri-methyl-sil-yl)phospho-rimido-yl]methanylyl-idene})bis-[1,1-diphenyl-N-(tri-methyl-sil-yl)-λ(5)-phosphanamine] pentane disolvate.

    PubMed

    Thirumoorthi, Ramalingam; Chivers, Tristram; Laitinen, Risto S

    2014-01-01

    The title compound, C62H78N4P4Se2Si4·2C5H12, is made up of two [SeC(PPh2NSiMe3)(PPh2NHSiMe3)] units related by an inversion center situated at the mid-point of the diselenide bond. It crystallized with two disordered mol-ecules of pentane used as solvent of crystallization. It is a rare example of an anti-periplanar diselenide and exhibits a long Se-Se bond of 2.4717 (8) Å. The Se-C bond length of 1.876 (5) Å is short in comparison with the range of values found for other diselenides (1.91-1.97 Å). The mol-ecule exhibits two intra-molecular N-H⋯N hydrogen bonds. In the crystal, there are no significant inter-molecular inter-actions present. One of the Me3Si- groups is disordered over two positions with a refined occupancy ratio of 0.708 (8):0.292 (8). The contribution of the disordered solvent to the scattering was removed with the SQUEEZE option of PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. The solvent contribution has been included in the reported mol-ecular weight and density. PMID:24526971

  9. 5-Amino-5'-bromo-6-(4-methyl-benzo-yl)-8-nitro-2,3-di-hydro-1H-spiro-[imidazo[1,2-a]pyridine-7,3'-indolin]-2'-one including an unknown solvate.

    PubMed

    Nagalakshmi, R A; Suresh, J; Sivakumar, S; Kumar, R Ranjith; Lakshman, P L Nilantha

    2014-07-01

    In the title compound, C22H18BrN5O4, the central six-membered ring, derived from 1,4-di-hydro-pyridine, adopts a distorted boat conformation with a puckering amplitude of 0.197 (3) Å, the imidazole ring adopts a twisted conformation with a puckering amplitude of 0.113 (3) Å, and the oxindole moiety is planar with an r.m.s. deviation of 0.0125 Å. Two intra-molecular N-H⋯O hydrogen bonds are formed, each closing an S(6) loop. In the crystal, strong N-H⋯O hydrogen bonds lead to the formation of zigzag chains along the c axis. These are consolidated in the three-dimensional crystal packing by weak N-H⋯O hydrogen bonding, as well as by C-H⋯O, C-H⋯Br and C-H⋯π inter-actions. A small region of electron density well removed from the main mol-ecule was removed with the SQUEEZE procedure in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155] following unsuccessful attempts to model it as a plausible solvent mol-ecule. The unit-cell characteristics do not take into account this feature of the structure. PMID:25161594

  10. Poly[[di-aqua-[μ-1,4-bis(pyridin-4-ylmeth-yl)piperazine-κ(2) N:N']{μ-2,2'-[(1,4-phenyl-ene)bis(-oxy)]di-acetato-κ(2) O:O'}cobalt(II)] penta-hydrate].

    PubMed

    Sample, Alexander D; LaDuca, Robert L

    2014-06-01

    In the title compound, {[Co(C10H8O6)(C16H20N4)(H2O)2]·5H2O} n , octa-hedrally coordinated Co(II) ions on crystallographic inversion centres are bound by trans O atoms belonging to two hydro-quinone-O,O'-di-acetate (hqda) anions {systematic name: 2,2'-[(1,4-phenyl-ene)bis-(-oxy)]di-acetate}, two trans-pyridine N-donor atoms from two bis-(pyridin-4-ylmeth-yl)piperazine (4-bpmp) ligands, and two trans aqua ligands. The exobidentate hqda and 4-bpmp ligands form [Co(hqda)(4-bpmp)(H2O)2] n coordination polymer layers parallel to (110) that are anchored into the full crystal structure by O-H⋯O hydrogen bonding between aqua ligands and ligated hqda O atoms. Disordered water mol-ecules of crystallization occupy incipient channels along [100]. However, these could not modeled reliably and so they were treated with SQUEEZE in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]; the crystal data take the presence of these mol-ecules into account. The crystal under investigation was twinned by non-merohedry, the twin fraction of the components being 53.3% and 46.7%. Only data from the major twin component were used in the refinement. PMID:24940193

  11. catena-Poly[[[iodidocopper(I)]-{μ-N-[(pyridin-2-yl-κN)methyl-idene]pyridin-3-amine-κ(2)N(3):N(1)}] acetonitrile hemisolvate].

    PubMed

    Mahmoudi, Ali; Dehghanpour, Saeed; Babakhodaverdi, Mojtaba

    2012-10-01

    In the asymmetric unit of the title polymeric complex, {[CuI(C(11)H(9)N(3))]·0.5CH(3)CN}(n), there are two Cu(I) atoms, two N-[(pyridin-2-yl-κN)methyl-idene]pyridin-3-amine (PyPy) ligands and two I atoms. Both Cu(I) atoms have a distorted tetra-hedral geometry, each being coordinated by one I atom, two N atoms of one PyPy ligand and one N atom from an adjacent PyPy ligand. In the crystal, infinite helical chains of [Cu(2)(PyPy)(2)](n) are formed propagating along the b axis. These chains are linked via weak C-H⋯I hydrogen bonds and π-π stacking inter-actions [shortest centroid-centroid distance = 3.2727 (14) Å]. During the refinement, electron-density peaks were located that were believed to be highly disordered solvent mol-ecules (possibly acetonitrile). The SQUEEZE option in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155] indicated there were solvent cavities with a total volume of 196 Å(3) containing approximately 60 electrons per unit cell, which equated to one mol-ecule of acetonitrile per asymmetric unit. PMID:23125600

  12. Crystal structure of 5-amino-5'-chloro-6-(4-chloro-benzo-yl)-8-nitro-2,3-di-hydro-1H-spiro-[imidazo[1,2-a]pyridine-7,3'-indolin]-2'-one including an unknown solvent mol-ecule.

    PubMed

    Nagalakshmi, R A; Suresh, J; Sivakumar, S; Kumar, R Ranjith; Lakshman, P L Nilantha

    2014-09-01

    The asymmetric unit of the title compound, C21H15Cl2N5O4, contains two independent mol-ecules (A and B) having similar conformations. The amine (NH2) group forms an intra-molecular hydrogen bond with the benzoyl group, giving an S(6) ring motif in both mol-ecules. The central six-membered rings adopt sofa conformations and the imidazole rings are planar (r.m.s deviations = 0.0150 and 0.0166 Å). The pyridine and imidazole rings are inclined to one another by 3.54 (1) and 3.03 (1)° in mol-ecules A and B, respectively. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, forming chains along the a axis which enclose R 2 (2)(16) ring motifs. The rings are linked by weak N-H⋯O and C-H⋯O hydrogen bonds and C-H⋯π inter-actions forming sheets lying parallel to (001). A region of disordered electron density, most probably disordered solvent mol-ecules, occupying voids of ca 753 Å(3) for an electron count of 260, was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. Their formula mass and unit-cell characteristics were not taken into account during refinement. PMID:25309286

  13. (Acetonitrile){2-[bis-(pyridin-2-ylmethyl-κ(2)N)amino-κN]-N-(2,6-dimethyl-phen-yl)acetamide-κO}(perchlorato-κO)zinc (acetonitrile){2-[bis-(pyridin-2-ylmethyl-κ(2)N)amino-κN]-N-(2,6-dimethyl-phen-yl)acetamide-κO}zinc tris-(perchlorate).

    PubMed

    Astrand, Ove Alexander Høgmoen; Görbitz, Carl Henrik; Kristoffersen, Kenneth Aase; Rongved, Pål

    2013-02-01

    In the title salt, [Zn(C(22)H(24)N(4)O)(CH(3)CN)][Zn(ClO(4))(C(22)H(24)N(4)O)(CH(3)CN)](ClO(4))(3), two differently coordinated zinc cations occur. In the first complex, the metal ion is coordinated by the N,N',N'',O-tetra-dentate acetamide ligand and an acetonitrile N atom, generating an approximate trigonal-bipyramidal coordination geometry, with the O atom in an equatorial site and the acetonitrile N atom in an axial site. In the second complex ion, a perchlorate ion is also bonded to the zinc ion, generating a distorted trans-ZnO(2)N(4) octa-hedron. Of the uncoordinating perchlorate ions, one lies on a crystallographic twofold axis and one lies close to a twofold axis and has a site occupancy of 0.5. N-H⋯O and N-H⋯(O,O) hydrogen bonds are observed in the crystal. Disordered solvent mol-ecules occupy about 11% of the unit-cell volume; their contribution to the scattering was removed with the SQUEEZE routine of the PLATON program [Spek (2009 ▶). Acta Cryst. D65, 148-155.]. PMID:23424407

  14. (Z)-1-[(2E)-3,4-Diphenyl-2,3-di-hydro-1,3-thia-zol-2-yl-idene]-2-[1-(4-hy-droxy-phen-yl)ethyl-idene]hydrazinium bromide including an unknown solvate.

    PubMed

    Mague, Joel T; Mohamed, Shaaban K; Akkurt, Mehmet; Hassan, Alaa A; Albayati, Mustafa R

    2014-06-01

    In the title compound, C23H20N3OS(+)·Br(-), the di-hydro-thia-zole ring (r.m.s. deviation = 0.015 Å) is twisted with respect to each of the C- and N-bound phenyl rings and the hy-droxy-benzene ring, making dihedral angles of 76.0 (2), 71.2 (2) and 9.8 (2)°, respectively. In the crystal, inversion-related mol-ecules are linked by association of the bromide ions with the cations via N-H⋯Br and O-H⋯Br hydrogen-bonding inter-actions. These mol-ecules run in channels parallel to the a axis through face-to-face π-π stacking inter-actions between the hy-droxy-benzene rings [centroid-centroid distances = 3.785 (3) Å] which, in turn, are connected into layers parallel to (110) by weak C-H⋯π inter-actions. A small region of electron density well removed from the main mol-ecule and appearing disordered over a center of symmetry was removed with PLATON SQUEEZE [Spek (2009 ▶). Acta Cryst. D65, 148-15] following unsuccessful attempts to model it as plausible solvent molecule. The nature of the solvent was not known and hence, this is not taken into account when calculating M r and related data. PMID:24940233

  15. 5''-(4-Nitro-benzyl-idene)-7'-(4-nitro-phen-yl)-1''-methyl-1',3',5',6',7',7a'-hexa-hydro-dispiro-[ace-naphthyl-ene-1,5'-pyrrolo-[1,2-c][1,3]thia-zole-6',3''-piperidine]-2,4''(1H)-dione including an unknown solvate.

    PubMed

    Vishnupriya, R; Suresh, J; Sivakumar, S; Kumar, R Ranjith; Lakshman, P L Nilantha

    2013-01-01

    The title compound, C35H28N4O6S, crystallizes with two mol-ecules in the asymmetric unit. In both mol-ecules, the piperidine ring adopts a shallow-chair conformation, the thia-zole ring adopts a twisted conformation about the Cm-N bond (m = methine) and the pyrrole ring adopts an envelope conformation with the C atom shared with the thia-zole ring as the flap. In the crystal, inversion dimers linked by pairs of C-H⋯O inter-actions generate R 2 (2)(34) loops for one of the asymmetric mol-ecules. Further C-H⋯O links also involving the other mol-ecule lead to a three-dimesional network. The contribution of the highly disordered solvent to the scattering was removed with SQUEEZE option of PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. The solvent contribution is not included in the reported mol-ecular weight and density. PMID:24109305

  16. (R C,S Fe)-1-[3,5-Bis(trifluoro-meth-yl)phen-yl]-3-{1-[2-(diphenyl-phosphan-yl)ferro-cen-yl]eth-yl}thio-urea (unknown solvate).

    PubMed

    Ma, Peng-Fei; Zhang, Xiao-Rui; Ma, Jiang-Wei; Chen, Hui; Jiang, Ru

    2013-05-01

    In the molecule of the the title compound, [Fe(C5H5)(C28H22F6N2PS)], the absolute configuration is R C ,SFe . The dihedral angle between the trifluoro-methyl-substituted phenyl ring and the thio-urea plane is 41.8 (9)°. The iron atom is bound to the cyclo-penta-dienyl rings in the typical η(5)-manner in a close to eclipsed conformation. The crystal structure features N-H⋯S hydrogen bonds, with the S atom as an acceptor for both N-H groups, forming a layered arrangement parallel to (1-10). The two -CF3 groups are each disordered over two positions with refined occupancy rates for the major components of 0.66 (7) and 0.55 (5). The crystal was grown from mixed solvents (n-hexane and ethyl acetate). These solvents are disordered in the crystal and the resulting electron density was found to be uninterpretable. The solvent contribution to the structure factors was taken into account by back-Fourier transformation of all density found in the disordered solvent area using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. The formula mass and density do not take account of the solvent. PMID:23723760

  17. Di-μ-carbonyl-bis-[bis-(triphenyl-phos-phane)rhodium(0)](Rh-Rh) acetone disolvate.

    PubMed

    Gueorguieva, Petia G; Laneman, Scott A; Stanley, George G; Fronczek, Frank R; Watkins, Steven F

    2012-11-01

    The dirhodium complex, [Rh(2)(C(18)H(15)P)(4)(CO)(2)]·2(CH(3))(2)CO, has crystallographic twofold symmetry and the Rh-Rh distance is 2.6266 (8) Å. The four atoms proximate to each Rh atom [Rh-P = 2.3222 (7) and 2.3283 (8) Å, and Rh-C = 1.961 (3) and 2.045 (3) Å] form a distorted tetra-hedron with large deviations from the putative tetra-hedral angles [r.m.s. deviation = 23 (1)°]. The six angles more closely approximate those of a trigonal bipyramid [r.m.s. deviation = 14 (1)°] with one missing equatorial ligand. The two bridging carbonyl ligands are much more linearly coordinated to one Rh [Rh-C O = 151.0 (2)°] than to the other [127.0 (2)°], and the two Rh(2)CO planes form a dihedral angle of 45.43 (5)°. The two acetone solvent mol-ecules are disordered, and their estimated scattering contribution was subtracted from the observed diffraction data using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst.D65, 148-155]. PMID:23284375

  18. Tetra-kis(μ3-2-{[1,1-bis-(hy-droxy-meth-yl)-2-oxidoeth-yl]imino-meth-yl}-6-nitro-pheno-lato)tetra-copper(II).

    PubMed

    Chygorin, Eduard N; Smal, Yuri O; Kokozay, Vladimir N; Omelchenko, Irina V

    2014-02-01

    The title cluster, [Cu4(C11H12N2O6)4], was obtained from the Cu(0)-FeCl2·4H2O-H4 L-Et3N-DMF reaction system (in air), where H4 L is 2-hy-droxy-methyl-2{[(2-hy-droxy-3-nitro-phen-yl)methyl-idene]amino}-propane-1,3-diol and DMF is di-methyl-formamide. The asymmetric unit consists of one Cu(2+) ion and one dianionic ligand; a -4 symmetry element generates the cluster, which contains a {Cu4O4} cubane-like core. The metal ion has an elongated square-based pyramidal CuNO4 coordination geometry with the N atom in a basal site. An intra-molecular O-H⋯O hydrogen bond is observed. The solvent mol-ecules were found to be highly disordered and their contribution to the scattering was removed with the SQUEEZE procedure in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155], which indicated a solvent cavity of volume 3131 Å(3) containing approximately 749 electrons. These solvent molecules are not considered in the given chemical formula. PMID:24764821

  19. trans-Dichloridobis{dicyclo-hex-yl[4-(dimethyl-amino)-phen-yl]phosphane-κP}platinum(II) dichloro-methane disolvate.

    PubMed

    Davis, Wade L; Meijboom, Reinout

    2012-12-01

    In the title complex, trans-[PtCl2{P(C6H11)2(4-Me2NC6H4)}2]·2CH2Cl2, the Pt(II) atom is located on an inversion centre, resulting in a trans-square-planar geometry. Important geometric parameters are the Pt-P and Pt-Cl bond lengths of 2.3258 (6) and 2.3106 (6) Å, respectively, and the P-Pt-Cl angles of 89.64 (2) and 90.36 (2)°. The effective cone angle for the dicyclo-hex-yl[4-(dimethyl-amino)-phen-yl]phosphane unit was calculated to be 164°. The compound crystallizes with two dichloro-methane solvent mol-ecules; one of which is severely disordered and was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. PMID:23468763

  20. 2-(2-Chloro-phen-yl)-N-cyclo-hexyl-2-oxoacetamide.

    PubMed

    Jin, Xiu-Dan; Wu, Jin-Long

    2013-04-01

    In the title compound, C14H16ClNO2, the cyclo-hexyl ring has a chair conformation. The dihedral angle between the benzene ring and the mean plane of the four planar C atoms of the cyclo-hexyl ring is 45.2 (3)°. The two carbonyl groups are trans to one another, with an O=C-C=O torsion angle of -137.1 (3)°. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds forming chains propagating along [001]. A region of disordered electron density, situated near the unit-cell corners, was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. It gave a solvent-accessible void of ca 400 Å(3) for only 21 electrons. It is probably due to traces of the solvent of crystallization and was not taken into account during structure refinement. PMID:23634053

  1. (1,6,7,12-Tetra-aza-perylene-κ(2) N,N')bis-(4,4',5,5'-tetra-methyl-2,2'-bipyridyl-κ(2) N,N')ruthenium(II) bis-(hexa-fluorido-phosphate) aceto-nitrile tris-olvate.

    PubMed

    Brietzke, Thomas; Kässler, Daniel; Kelling, Alexandra; Schilde, Uwe; Holdt, Hans-Jürgen

    2014-06-01

    In the title compound, rac-[Ru(C14H16N2)2(C16H8N4)](PF6)2·3C2H3N, discrete dimers of complex cations, [Ru(tmbpy)2-tape](2+), of opposite chirality are formed (tmbpy = tetra-methyl-bipyridine; tape = tetraazaperylene), held together by π-π stacking inter-actions between the tetra-aza-perylene moieties with centroid-centroid distances in the range 3.563 (3)-3.837 (3) Å. These inter-actions exhibit a parallel displaced π-π stacking mode. Additional weak C-H⋯π-ring and C-H⋯N and C-H⋯F inter-actions are found, leading to a three-dimensional architecture. The Ru(II) atom is coordinated in a distorted octa-hedral geometry. The counter-charge is provided by two hexa-fluorido-phosphate anions and the asymmetric unit is completed by three aceto-nitrile solvent mol-ecules of crystallization. Four F atoms of one PF6 (-) anion are disordered over three sets of sites with occupancies of 0.517 (3):0.244 (3):0.239 (3). Two aceto-nitrile solvent mol-ecules are highly disordered and their estimated scattering contribution was subtracted from the observed diffraction data using the SQUEEZE option in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. PMID:24940217

  2. An unknown solvate of 1-(2,4-di-chloro-benz-yl)-4-[(4-methyl-phen-yl)sulfon-yl]piperazine.

    PubMed

    Sreenivasa, S; Manojkumar, K E; Anitha, H C; Suchetan, P A; Palakshamurthy, B S; Jayashree, Yenagi; Tonannavar, J

    2013-05-01

    In the title compound, C18H20Cl2N2O2S, the piperazine ring adopts a chair conformation. The dihedral angle between the sulfonyl-bound benzene ring and the best-fit plane through the six non-H atoms of the piperazine ring is 72.22 (12)°; those between the di-chloro-benzene ring and the sulfonyl and piperazine rings are 2.44 (13) and 74.16 (2)°, respectively. In the crystal, mol-ecules are connected through weak C-H⋯O inter-actions into a hexa-meric unit generating a R 6 (6)(60) motif in the ab plane. The mol-ecules are also connected into C(4) chains through weak C-H⋯N inter-actions. The solvent used to grow the crystal was a mixture of di-chloro-methane and methanol, but the resulting electron density was uninter-pretable. The solvent contribution to the scattering was removed with the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. The formula mass and unit-cell characteristics do not take into account the disordered solvent. PMID:23723926

  3. (η(6)-Benzene)(carbonato-κ(2) O,O')[di-cyclohex-yl(naphthalen-1-ylmeth-yl)phosphane-κP]ruthenium(II) chloro-form tris-olvate.

    PubMed

    Gowrisankar, Saravanan; Neumann, Helfried; Spannenberg, Anke; Beller, Matthias

    2014-07-01

    The title compound, [Ru(CO3)(η(6)-C6H6){(C6H11)2P(CH2C10H7)}]·3CHCl3, was synthesized by carbonation of [RuCl2(η(6)-C6H6){(C6H11)2P(CH2C10H7)}] with NaHCO3 in methanol at room temperature. The Ru(II) atom is surrounded by a benzene ligand, a chelating carbonate group and a phosphane ligand in a piano-stool configuration. The crystal packing is consolidated by C-H⋯O and C-H⋯Cl hydrogen-bonding inter-actions between adjacent metal complexes and between the complexes and the solvent mol-ecules. The asymmetric unit contains one metal complex and three chloro-form solvent mol-ecules of which only one was modelled. The estimated diffraction contributions of the other two strongly disordered chloro-form solvent mol-ecules were substracted from the observed diffraction data using the SQUEEZE procedure in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. PMID:25161531

  4. Crystal structure of 3-(4-chloro-phen-oxy)-4-(2-nitro-phen-yl)azetidin-2-one with an unknown solvate.

    PubMed

    Çelikesir, Sevim Türktekin; Akkurt, Mehmet; Jarrahpour, Aliasghar; Shafie, Habib Allah; Çelik, Ömer

    2015-01-01

    In the title compound, C15H11ClN2O4, the central β-lactam ring is approximately planar [maximum deviation = 0.044 (2) Å for the N atom from the mean plane] and subtends dihedral angles of 61.17 (11) and 40.21 (12) °, respectively, with the nitro and chloro-benzene rings. Both substituents lie to the same side of the β-lactam core. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into C(4) chains propagating in [010]. The chains are cross-linked by C-H⋯O and weak C-H⋯π inter-actions, generating a three-dimensional network. The solvent mol-ecules were found to be highly disordered and their contribution to the scattering was removed with the SQUEEZE procedure in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155], which indicated a solvent cavity of volume 318 Å(3) containing approximately 114 electrons. These solvent mol-ecules are not considered in the given chemical formula and other crystal data. PMID:25705514

  5. Di-μ-carbonyl-bis­[bis­(triphenyl­phos­phane)rhodium(0)](Rh—Rh) acetone disolvate1

    PubMed Central

    Gueorguieva, Petia G.; Laneman, Scott A.; Stanley, George G.; Fronczek, Frank R.; Watkins, Steven F.

    2012-01-01

    The dirhodium complex, [Rh2(C18H15P)4(CO)2]·2(CH3)2CO, has crystallographic twofold symmetry and the Rh—Rh distance is 2.6266 (8) Å. The four atoms proximate to each Rh atom [Rh—P = 2.3222 (7) and 2.3283 (8) Å, and Rh—C = 1.961 (3) and 2.045 (3) Å] form a distorted tetra­hedron with large deviations from the putative tetra­hedral angles [r.m.s. deviation = 23 (1)°]. The six angles more closely approximate those of a trigonal bipyramid [r.m.s. deviation = 14 (1)°] with one missing equatorial ligand. The two bridging carbonyl ligands are much more linearly coordinated to one Rh [Rh—C O = 151.0 (2)°] than to the other [127.0 (2)°], and the two Rh2CO planes form a dihedral angle of 45.43 (5)°. The two acetone solvent mol­ecules are disordered, and their estimated scattering contribution was subtracted from the observed diffraction data using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155]. PMID:23284375

  6. Comment on the paper “Synthesis, growth, structural, spectral, thermal, chemical etching, linear and nonlinear optical and mechanical studies of an organic single crystal 4-Chloro 4-Nitrostilbene (CONS): A potential NLO material” by P.M. Dinakaran, S. Kalainathan [Spectrochim. Acta A 111 (2013) 123-130

    NASA Astrophysics Data System (ADS)

    Srinivasan, Bikshandarkoil R.; Dhuri, Sunder N.; Nadkarni, V. S.

    2014-01-01

    We argue that (trans)-4-chloro-4‧-nitrostilbene is not a new organic nonlinear optical material as claimed by Dinakaran and Kalainathan [P.M. Dinakaran, S. Kalainathan, Synthesis, growth, structural, spectral, thermal, chemical etching, linear and nonlinear optical and mechanical studies of an organic single crystal 4-Chloro 4-Nitrostilbene (CONS): a potential NLO material, Spectrochim. Acta A 111 (2013) 123-130], but instead a well-known compound whose synthesis, spectral data, single crystal structure and second harmonic generation (SHG) efficiency are well documented in the literature. The title paper is completely erroneous.

  7. Comment on the paper "Synthesis, growth, structural, spectral, thermal, chemical etching, linear and nonlinear optical and mechanical studies of an organic single crystal 4-chloro 4-nitrostilbene (CONS): a potential NLO material" by P.M. Dinakaran, S. Kalainathan [Spectrochim. Acta A 111 (2013) 123-130].

    PubMed

    Srinivasan, Bikshandarkoil R; Dhuri, Sunder N; Nadkarni, V S

    2014-01-01

    We argue that (trans)-4-chloro-4'-nitrostilbene is not a new organic nonlinear optical material as claimed by Dinakaran and Kalainathan [P.M. Dinakaran, S. Kalainathan, Synthesis, growth, structural, spectral, thermal, chemical etching, linear and nonlinear optical and mechanical studies of an organic single crystal 4-Chloro 4-Nitrostilbene (CONS): a potential NLO material, Spectrochim. Acta A 111 (2013) 123-130], but instead a well-known compound whose synthesis, spectral data, single crystal structure and second harmonic generation (SHG) efficiency are well documented in the literature. The title paper is completely erroneous.

  8. 4-(4-Bromo-phen-yl)-7,7-dimethyl-2-methyl-amino-3-nitro-7,8-di-hydro-4H-chromen-5(6H)-one including an unknown solvate.

    PubMed

    Inglebert, S Antony; Kamalraja, Jayabal; Sethusankar, K; Vasuki, Gnanasambandam

    2014-05-01

    In the title compound, C18H19BrN2O4, the chromene unit is not quite planar (r.m.s. deviation = 0.199 Å), with the methyl C atoms lying 0.027 (4) and 1.929 (4) Å from the mean plane of the chromene unit. The six-membered carbocyclic ring of the chromene moiety adopts an envelope conformation, with the dimethyl-substituted C atom as the flap. The methyl-amine and nitro groups are slightly twisted from the chromene moiety, with C-N-C-O and O-N-C-C torsion angles of 2.7 (4) and -0.4 (4)°, respectively. The dihedral angle between the mean plane of the chromene unit and the benzene ring is 85.61 (13)°. An intra-molecular N-H⋯O hydrogen bond generates an S(6) ring motif, which stabilizes the mol-ecular conformation. In the crystal, mol-ecules are linked via N-H⋯O hydrogen bonds, forming hexa-gonal rings lying parallel to the ab plane. A region of disordered electron density, most probably disordered ethanol solvent mol-ecules, occupying voids of ca 432 Å(3) for an electron count of 158, was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. Their formula mass and unit-cell characteristics were not taken into account during refinement. PMID:24860381

  9. Ethyl-enedi-ammonium sodium tetra-kis-[bis-(ethyl-enedi-amine-κ(2) N,N')(oxalato-κ(2) O (1),O (2))cobalt(III)] [penta-hydrogen di(phosphato-octa-deca-tungstate)] tetra-deca-hydrate.

    PubMed

    Zhang, Shuzhuo; Wang, Jing; Xu, Yun

    2013-10-16

    The title compound, Na(C2H10N2)[Co(C2O4)(C2H8N2)2]4[H5(P2W18O62)2]·14H2O, prepared under hydro-thermal conditions, consists of two Dawson-type [P2W18O62](6-) anions, four isolated [Co(en)2(ox)](+) cations (en = ethyl-enedi-amine and ox = oxalate), one Na(+) cation, one [H2en](2+) cation, and a number of ordered (14) and disordered solvent water mol-ecules. The [P2W18O62](6-) polyoxidometalate anion has site symmetry 1 and contains two structurally distinct types of W atoms: viz. six W atoms on vertical pseudo-mirror planes grouped in two sets of three, and 12 equatorial W atoms that do not lie in the pseudo-mirror planes grouped in two sets of six. In each [Co(en)2(ox)](+) cation, the Co(III) ion is coordinated by four N atoms from two en ligands and two O atoms from the ox ligands, completing a distorted octa-hedral structure. The sodium cation lies on an inversion centre and additionally links the complex cations and anions. In the crystal, the various units are linked by N-H⋯O and O-H⋯O hydrogen bonds, which together with C-H⋯O hydrogen bonds form a three-dimensional structure. The contribution of a region of disordered electron density, possibly highly disordered solvent water mol-ecules, to the scattering was removed with the SQUEEZE option of PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. To equilibrate the charges five H(+) ions have been added to the polyoxidometalate. These H(+) ions and the disordered solvent contribution were not included in the reported mol-ecular weight and density. PMID:24454036

  10. Periodic entanglement III: tangled degree-3 finite and layer net intergrowths from rare forests.

    PubMed

    Evans, Myfanwy E; Hyde, Stephen T

    2015-11-01

    Entanglements of two-dimensional honeycomb nets are constructed from free tilings of the hyperbolic plane (H2) on triply periodic minimal surfaces. The 2-periodic nets that comprise the structures are guaranteed by considering regular, rare free tilings in H2. This paper catalogues an array of entanglements that are both beautiful and challenging for current classification techniques, including examples that are realized in metal-organic materials. The compactification of these structures to the genus-3 torus is considered as a preliminary method for generating entanglements of finite θ-graphs, potentially useful for gaining insight into the entanglement of the periodic structure. This work builds on previous structural enumerations given in Periodic entanglement Parts I and II [Evans et al. (2013). Acta Cryst. A69, 241-261; Evans et al. (2013). Acta Cryst. A69, 262-275]. PMID:26522409

  11. From deep TLS validation to ensembles of atomic models built from elemental motions. Addenda and corrigendum

    PubMed Central

    Urzhumtsev, Alexandre; Afonine, Pavel V.; Van Benschoten, Andrew H.; Fraser, James S.; Adams, Paul D.

    2016-01-01

    Researcher feedback has indicated that in Urzhumtsev et al. [(2015) Acta Cryst. D71, 1668–1683] clarification of key parts of the algorithm for interpretation of TLS matrices in terms of elemental atomic motions and corresponding ensembles of atomic models is required. Also, it has been brought to the attention of the authors that the incorrect PDB code was reported for one of test models. These issues are addressed in this article. PMID:27599739

  12. Triclinic polymorph of 4-[4-(4-formyl-phen-oxy)but-oxy]benzaldehyde.

    PubMed

    Balić, Tomislav; Marković, Berislav; Balić, Ivana

    2013-01-01

    The title compound, C18H18O4, is a triclinic polymorph of the previously reported monoclinic polymorph [Han & Zhen (2005 ▶). Acta Cryst. E61, o4358-o4359]. In the crystal of the triclinic polymorph, molecules are linked by two pairs of C-H⋯O hydrogen bonds, forming a two-dimensional network parallel to (102), and enclosing loops with graph set motifs of R2(2)(8) and R2(2)(6). PMID:23476387

  13. Bis(1,3-dimethyl-1H-imidazolium) hexa-fluoro-silicate methanol 0.33-solvate.

    PubMed

    Tian, Chong; Nie, Wanli; Borzov, Maxim V

    2013-01-01

    The title compound, 6C5H9N2 (+)·3SiF6 (2-)·CH3OH, (I), was prepared by recrystallization of the crude salt from methanol along with solvent-free 2C5H9N2 (+)·SiF6 (2-) (II). Crystals of these solvatomorphs can be separated manually. The solvate (I) crystallizes in a rare hexa-gonal space group P6/mcc. Its asymmetric unit comprises one half of an imidazolium cation bis-ected by the crystallographic m-plane, one-sixth and one-twelfth of two crystallographically independent SiF6 (2-) dianions (Si atoms are located on the 3.2 and 6/m inversion centres), and one-twelfth of a methanol mol-ecule (C atoms are situated on the 622 inversion centres, other atoms are disordered between general positions). In (I), all F atoms of 3.2-located SiF6 (2-) dianions participate in the formation of symmetry-equivalent contacts to the H atoms of imidazolium fragments, thus forming rod-type ensembles positioned on the -6 axes. These 'pillar' rods are, in turn, F⋯H inter-linked through SiF6 (2-) dianions disordered around the 6/m centres. The twelvefold disordered methanol mol-ecules are appended to this array by O-H⋯F hydrogen bonds to the 6/m located SiF6 (2-) dianions. In terms of graph-set notation, the first and second level networks in (I) are N 1 = C 2 (2)(7)[3R 4 (4)(14)]D 2 (2)(4) and N 2 = D 2 (2)(5) (C-H⋯O hydrogen bonds are not considered). After locating all symmetrically independent atoms in the cation and anions, there remained a strong (> 3 e Å(-3)) residual electron density peak located at the 622 inversion centre. Treatment of this pre-refined model with the SQUEEZE procedure in PLATON [Spek (2009). Acta Cryst. D65, 148-155] revealed two voids per unit cell, indicative of the presence of the solvent methanol mol-ecule disordered about the 622 inversion centre. PMID:24109311

  14. The Crystallography of Quasicrystals

    NASA Astrophysics Data System (ADS)

    Rabson, David Alan

    A century ago, E. S. Fedorov, A. Schonflies, and W. Barlow, working independently, classified the 230 distinct symmetry groups of objects repeated periodically in three-dimensional space. The 230 space groups determine the symmetries of macroscopic properties and provide crystallographers with their most important tool in deducing structure; as such, they find use in biology, organic chemistry, and virology as well as in physics, geology, and materials science. With the discovery in 1984 of quasicrystals, well-ordered but aperiodic metallic alloys with crystallographically forbidden rotational symmetries, the need arose to develop a space-group theory for these new materials. Based on the work by Rokhsar, Wright, and Mermin^1 in two dimensions, Rabson, Mermin, Rokhsar, and Wright have classified all quasicrystal and crystal three -dimensional axial space groups.^2 Our classification, proceeding in reciprocal space, is elementary, does not rely on projecting higher-dimensional crystallographic space groups, and is valid for arbitrary rotational symmetry. As an additional illustration of quasicrystallographic space groups, I derive and demonstrate algorithms that produce two-dimensional tilings of rhombi with each of the possible plane-group symmetries.^3 While the analogous task for crystallographic plane groups is trivial, the lack of translational symmetry in a quasicrystal tiling makes these constructions interesting. Since the symmetry of a quasicrystal appears more naturally in reciprocal than in direct space, it is not surprising that some of the resulting tilings seem intricate, although in fact their symmetries are quite simple. ftn^1 Acta Cryst. A44, 197-211 (1988). ^2 "The Space Groups of Axial Crystals and Quasicrystals," preprint. ^3See also Rabson, Ho, and Mermin, Acta Cryst. A44, 678 (1988) and Acta Cryst. A45, 538 (1989).

  15. Computer-simulated X-ray three-beam pinhole topographs for spherical silicon crystals.

    PubMed

    Okitsu, Kouhei

    2011-11-01

    X-ray three-beam pinhole topograph images for spherical silicon crystals were computer-simulated based on the n-beam Takagi-Taupin (T-T) equation. They were compared with those for parallel-plate crystals. The procedure to integrate the n-beam T-T equation for a crystal with an arbitrary shape has been validated in a separate paper [Okitsu et al. (2011), Acta Cryst. A67, 550-556] from comparison between experimentally obtained and computer-simulated six-beam pinhole topographs for a channel-cut silicon crystal.

  16. A New, More Stable Polymorphic Form of Otilonium Bromide: Solubility, Crystal Structure, and Phase Transformation.

    PubMed

    Vega, Daniel R; Halac, Emilia; Segovia, Luciano; Baggio, Ricardo

    2016-10-01

    A new polymorphic form of otilonium bromide is presented (Form I), and a thorough analysis of its crystal and molecular structure is performed. The compound suffers a temperature-driven first-order phase transition at about 396 K, which transforms it into the polymorph reported by Dapporto P and Sega A (Acta Cryst. 1986;C42:474-478) (Form II). Through thermal analysis and solubility experiments the relative stability of both crystal modifications were determined, confirming that at room temperature this new Form I is the more stable one, Form II existing just in a metastable state. PMID:27444388

  17. RbZnFe(PO4)2: synthesis and crystal structure

    PubMed Central

    Badri, Abdessalem; Ben Amara, Mongi

    2016-01-01

    A new iron phosphate, rubidium zinc iron(III) phosphate, RbZnFe(PO4)2, has been synthesized as single crystals by the flux method. This compound is isostructural to the previously reported KCoAl(PO4)2 [Chen et al. (1997 ▸). Acta Cryst. C53,1754–1756]. Its structure consists of a three-dimensional framework built up from corner-sharing PO4 and (Zn,Fe)O4 tetra­hedra. This mode of linkage forms channels parallel to the [100], [010] and [001] directions in which the Rb+ ions are located. PMID:27536385

  18. Crystal structure of benzene-1,3,5-tri-carb-oxy-lic acid-4-pyridone (1/3).

    PubMed

    Staun, Selena L; Oliver, Allen G

    2015-11-01

    Slow co-crystallization of a solution of benzene-1,3,5-tri-carb-oxy-lic acid with a large excess of 4-hy-droxy-pyridine produces an inter-penetrating, three-dimensional, hydrogen-bonded framework consisting of three 4-pyridone and one benzene-1,3,5-tri-carb-oxy-lic acid mol-ecules, C9H6O6·3C5H5NO. This structure represents an ortho-rhom-bic polymorph of the previously reported C-centered, monoclinic structure [Campos-Gaxiola et al. (2014 ▸). Acta Cryst. E70, o453-o454]. PMID:26594492

  19. Redetermination of tetra­kis(N,N-diethyl­dithio­carbamato)tin(IV)

    PubMed Central

    Okio, Coco K. Y. A.; Speziali, Nivaldo L.

    2009-01-01

    The crystal structure of the title compound, [Sn(C5H10NS2)4], was originally determined by Harreld & Schlemper [Acta Cryst. (1971), B27, 1964–1969] using intensity data estimated from Weissenberg films. In comparison with the previous refinement, the current redetermination reveals anisotropic displacement parameters for all non-H atoms, localization of the H atoms, and higher precision of lattice parameters and inter­atomic distances. The complex features a distorted S6 octa­hedral coordination geometry for tin and a cis disposition of the monodentate dithio­carbamate ligands. PMID:21583036

  20. A monoclinic form of dendocarbin A: a borderline case of one-dimensional isostructural polymorphism.

    PubMed

    Paz, Cristian; Burgos, Viviana; Suarez, Sebastián; Baggio, Ricardo

    2015-04-01

    The title compound, dendocarbin A [systematic name: (1R,5aS,9aS,9bR)-1-hydroxy-6,6,9a-trimethyldodecahydronaphtho[1,2-c]furan-3-one], C15H22O3, is a sesquiterpene lactone isolated from Drimys winteri var chilensis. The monoclinic phase described herein displays an identical molecular structure to the orthorhombic phase that we reported previously [Paz Robles et al. (2014). Acta Cryst. C70, 1007-1010], while varying significantly in chain pitch, and can thus be considered as a borderline case of one-dimensional isostructural polymorphism.

  1. Cinchonidinium chloride monohydrate

    PubMed Central

    Ni, Shi-Feng; Ma, Lin Lin; Zhao, Gui Fang; Sun, Wen Ji; Jin, Zhi Min

    2008-01-01

    In the title salt, C19H23N2O+·Cl−·H2O, the ions and the water mol­ecule are held together by O—H⋯Cl, N—H⋯Cl, O—H⋯O, O—H⋯N and C—H⋯Cl hydrogen bonds, forming a three-dimensional framework. The vinyl group is disordered over two orientations with refined occupancies of 0.564 (16) and 0.436 (16). The cell parameters of the title compound have been reported previously [Griffiths (1952 ▶). Acta Cryst. 5, 290–291]. PMID:21200758

  2. A New, More Stable Polymorphic Form of Otilonium Bromide: Solubility, Crystal Structure, and Phase Transformation.

    PubMed

    Vega, Daniel R; Halac, Emilia; Segovia, Luciano; Baggio, Ricardo

    2016-10-01

    A new polymorphic form of otilonium bromide is presented (Form I), and a thorough analysis of its crystal and molecular structure is performed. The compound suffers a temperature-driven first-order phase transition at about 396 K, which transforms it into the polymorph reported by Dapporto P and Sega A (Acta Cryst. 1986;C42:474-478) (Form II). Through thermal analysis and solubility experiments the relative stability of both crystal modifications were determined, confirming that at room temperature this new Form I is the more stable one, Form II existing just in a metastable state.

  3. RbZnFe(PO4)2: synthesis and crystal structure.

    PubMed

    Badri, Abdessalem; Ben Amara, Mongi

    2016-08-01

    A new iron phosphate, rubidium zinc iron(III) phosphate, RbZnFe(PO4)2, has been synthesized as single crystals by the flux method. This compound is isostructural to the previously reported KCoAl(PO4)2 [Chen et al. (1997 ▸). Acta Cryst. C53,1754-1756]. Its structure consists of a three-dimensional framework built up from corner-sharing PO4 and (Zn,Fe)O4 tetra-hedra. This mode of linkage forms channels parallel to the [100], [010] and [001] directions in which the Rb(+) ions are located. PMID:27536385

  4. Complete crystal structure of decafluorocyclohex-1-ene at 4.2 K from original neutron diffraction data.

    PubMed

    Solovyov, Leonid A; Fedorov, Alexandr S; Kuzubov, Aleksandr A

    2014-04-01

    The crystal structure model of decafluorocyclohex-1-ene at 4.2 K derived from simulated powder diffraction data and solid-state energy minimization [Smrčok et al. (2013). Acta Cryst. B69, 395-404] is found to be incomplete. In this study it is completed by an additional alternative molecular orientation revealed from the difference density analysis and direct space search. The structure is refined by the derivative difference method in the rigid-body approximation leading to perfect agreement between observed and calculated neutron powder patterns. PMID:24675609

  5. The joint probability distribution function of structure factors with rational indices. V. The estimates.

    PubMed

    Giacovazzo; Siliqi; Fernández-Castaño; Comunale

    1999-05-01

    The probabilistic formulae [Giacovazzo, Siliqi & Fernández-Castaño (1999). Acta Cryst. A55, 512-524] relating standard and half-integral index reflections are modified for practical applications. The experimental tests prove the reliability of the probabilistic relationships. The approach is further developed to explore whether the moduli of the half-integral index reflections can be evaluated in the absence of phase information; i.e. by exploiting the moduli of the standard reflections only. The final formulae indicate that estimates can be obtained, even though the reliability factor is a constant.

  6. Digitalization of “Acta Stomatologica Croatica” Journal (1966;1 – 1999;33)

    PubMed Central

    Borić, Vesna

    2014-01-01

    Summary Modern documents, scientific articles and books are primarily issued in electronic form and their availability depends on the publisher's, or the document owner's, business ethics. The primary purpose of publishing a scientific article is to communicate with the scientific and professional community; therefore, the published article has to be available worldwide. The question is: Who really needs scientific papers from the 1960's? In cases of brilliant and bold visionaries, new concepts and scientific discoveries often come before their time; hence they have to be "reinvented" decades later. Besides, the scientists of today can enter the spiritual spheres of their professional ancestors and give respect to their legacy.
We have processed more than 1 200 articles published by 1999 and entered more than
6 000 names and surnames of authors.

  7. Grazing-incidence small-angle X-ray scattering in a twofold rough-interface medium: a new theoretical approach using the q-eigenwave formalism.

    PubMed

    Chukhovskii, F N; Roshchin, B S

    2015-11-01

    Based on the rigorous Green function formalism to describe the grazing-incidence small-angle X-ray scattering (GISAXS) problem, a system of two linked integral equations is derived with respect to amplitudes of the reflected and transmitted plane q-eigenwaves (eigenstate functions) propagating through two homogeneous media separated from each other by a rough surface interface. To build up the coupled solutions of these basic equations beyond the perturbation theory constraint 2kσθ0 < 1, a simple iteration procedure is proposed as opposed to the self-consistent wave approach [Chukhovskii (2011). Acta Cryst. A67, 200-209; Chukhovski (2012). Acta Cryst. A68, 505-512]. Using the first-order iteration, analytical expressions for the averaged specular and non-specular scattering intensity distributions have been obtained. These expressions are further analysed in terms of the GISAXS parameters {k, θ, θ0} and surface finish ones {σ, l, h}, where θ and θ0 are the scattering and incidence angles of the X-rays, respectively, σ is the root-mean-square roughness, l is the correlation length, h is the fractal surface model index, k = 2π/λ, and λ is the X-ray wavelength. A direct way to determine the surface finish parameters from the experimental specular and diffuse scattering indicatrix scan data is discussed for an example of GISAXS measurements from rough surfaces of α-quartz and CdTe samples. PMID:26522410

  8. A polymorph of 2,4-dinitro­phenyl­hydrazine

    PubMed Central

    Amimoto, Kiichi; Nishiguchi, Hiromitsu

    2013-01-01

    The crystal structure of a previously unreported polymorph (form II) of 2,4-dinitro­phenyl­hydrazine (DNPH), C6H6N4O4, was determined at 90 K. The first polymorph (form I) is described in the monoclinic space group P21/c [Okabe et al. (1993 ▶). Acta Cryst. C49, 1678–1680; Wardell et al. (2006 ▶). Acta Cryst. C62, o318–320], whereas form II is in the monoclinic space group Cc. The mol­ecular structures in forms I and II are closely similar, with the nitro groups at the 2- and 4-positions being almost coplanar with the benzene ring [dihedral angles of 3.54 (1) and 3.38 (1)°, respectively in II]. However, their packing arrangements are completely different. Form I exhibits a herringbone packing motif, whereas form II displays a coplanar chain structure. Each chain in form II is connected to adjacent chains by the inter­molecular inter­action between hydrazine NH2 and 2-nitro groups, forming a sheet normal to (101). The sheet is stabilized by N—H⋯π inter­actions. PMID:23476598

  9. Charge distribution as a tool to investigate structural details. III. Extension to description in terms of anion-centred polyhedra.

    PubMed

    Eon, Jean-Guillaume; Nespolo, Massimo

    2015-02-01

    The charge distribution (CHARDI) method is a self-consistent generalization of Pauling's concept of bond strength which does not make use of empirical parameters but exploits the experimental geometry of the coordination polyhedra building a crystal structure. In the two previous articles of this series [Nespolo et al. (1999). Acta Cryst. B55, 902-916; Nespolo et al. (2001). Acta Cryst. B57, 652-664], we have presented the features and advantages of this approach and its extension to distorted and heterovalent polyhedra and to hydrogen bonds. In this third article we generalize CHARDI to structures based on anion-centred polyhedra, which have drawn attention in recent years, and we show that computations based on both descriptions can be useful to obtain a deeper insight into the structural details, in particular for mixed-valence compounds where CHARDI is able to give precise indications on the statistical distribution of atoms with different oxidation number. A graph-theoretical description of the structures rationalizes and gives further support to the conclusions obtained via the CHARDI approach.

  10. The structure and refinement of apocrustacyanin C2 to 1.3 A resolution and the search for differences between this protein and the homologous apoproteins A1 and C1.

    PubMed

    Habash, Jarjis; Helliwell, John R; Raftery, James; Cianci, Michele; Rizkallah, Pierre J; Chayen, Naomi E; Nneji, Gwen A; Zagalsky, Peter F

    2004-03-01

    The blue carotenoprotein alpha-crustacyanin of Homarus gammarus lobster carapace is comprised chemically of five 20 kDa subunits. Only two genes for the proteins have been isolated (J. B. C. Findlay, personal communication) and the five apoproteins fall into two sets of homologous proteins based on their chemical properties (CRTC, consisting of apoproteins C(1), C(2) and A(1), and CRTA, consisting of apoproteins A(2) and A(3)). The diffraction quality of apo C(2) has been improved from 2.2 to 1.3 A and its structure solved. The structure is compared with the A(1) and C(1) proteins determined at 1.4 A [Cianci et al. (2001), Acta Cryst. D57, 1219-1229] and 1.15 A, respectively [Gordon et al. (2001), Acta Cryst. D57, 1230-1237] and found to be very similar. Normalized B-factor difference plots per residue of different types were used to try to find chemically modified residues; none were found at these resolutions. It remains possible that the differences between the CRTC proteins result from differences in amidation. By comparison of a crystal grown with glycerol (studied at 1.6 A) and one grown without glycerol (studied at 1.3 A) it was seen that glycerol bound at the astaxanthin site. PMID:14993674

  11. The joint probability distributions of structure-factor doublets in displacive incommensurately modulated structures and their applicability to direct methods.

    PubMed

    Peschar, R; Israël, R; Beurskens, P T

    2001-07-01

    In 1993, alternative normalized structure factors for incommensurately modulated structures were defined [Lam, Beurskens & van Smaalen (1993). Acta Cryst. A49, 709-721]. The probability distribution associated with the structure invariants E(-H)E(H')E(H - H') has approximately the same functional form as the Cochran distribution. It was shown, however, that triplet-phase relations are relatively less reliable when satellites are involved [de Gelder, Israël, Lam, Beurskens, van Smaalen, Fu & Fan (1996). Acta Cryst. A52, 947-954]. In the present paper, an alternative approach is presented: instead of studying the distribution of a three-phase invariant, the probability distribution of the phase sum of two first-order satellite reflections (h,k,l,1 and h',k',l',-1) has been derived under the assumption that the phase of the associated main reflection (h + h',k + k',l + l',0) can be calculated from the known main (or averaged) structure. Intensive tests with randomly generated artificial structures and one real structure show a significant improvement of direct-methods phase-sum statistics. Functional similarities with conventional direct methods, employing normalized structure factors and the Cochran distribution, are discussed.

  12. The structure and refinement of apocrustacyanin C2 to 1.3 A resolution and the search for differences between this protein and the homologous apoproteins A1 and C1.

    PubMed

    Habash, Jarjis; Helliwell, John R; Raftery, James; Cianci, Michele; Rizkallah, Pierre J; Chayen, Naomi E; Nneji, Gwen A; Zagalsky, Peter F

    2004-03-01

    The blue carotenoprotein alpha-crustacyanin of Homarus gammarus lobster carapace is comprised chemically of five 20 kDa subunits. Only two genes for the proteins have been isolated (J. B. C. Findlay, personal communication) and the five apoproteins fall into two sets of homologous proteins based on their chemical properties (CRTC, consisting of apoproteins C(1), C(2) and A(1), and CRTA, consisting of apoproteins A(2) and A(3)). The diffraction quality of apo C(2) has been improved from 2.2 to 1.3 A and its structure solved. The structure is compared with the A(1) and C(1) proteins determined at 1.4 A [Cianci et al. (2001), Acta Cryst. D57, 1219-1229] and 1.15 A, respectively [Gordon et al. (2001), Acta Cryst. D57, 1230-1237] and found to be very similar. Normalized B-factor difference plots per residue of different types were used to try to find chemically modified residues; none were found at these resolutions. It remains possible that the differences between the CRTC proteins result from differences in amidation. By comparison of a crystal grown with glycerol (studied at 1.6 A) and one grown without glycerol (studied at 1.3 A) it was seen that glycerol bound at the astaxanthin site.

  13. Determination of the electrostatic potential and electron density of silicon using convergent-beam electron diffraction.

    PubMed

    Ogata, Yoichiro; Tsuda, Kenji; Tanaka, Michiyoshi

    2008-09-01

    A structure-analysis method using convergent-beam electron diffraction (CBED) developed by Tsuda et al. [Tsuda & Tanaka (1999), Acta Cryst. A55, 939-954; Tsuda, Ogata, Takagi, Hashimoto & Tanaka (2002), Acta Cryst. A58, 514-525] has been applied to the determination of the electrostatic potential and electron density of crystalline silicon. CBED patterns recorded at nine different incidences are simultaneously used to improve the accuracy of the refinement. The Debye-Waller factor and low-order structure factors of silicon have been successfully refined only using CBED data. The electrostatic potential and electron-density distribution have been reconstructed from the refined parameters. The latter clearly shows the bonding electrons between the nearest neighbor atoms. The obtained results are compared with the results of other CBED and recent X-ray diffraction experiments. The influence of the number of refined low-order structure factors on the electron density is discussed. The effect of the reduction of experimental data points on the accuracy of the refined parameters is also examined.

  14. Morphotropism: link between the isostructurality, polymorphism and (stereo)isomerism of organic crystals.

    PubMed

    Kálmán, Alajos

    2005-10-01

    An ongoing analysis of the supramolecular self-assembly of disubstituted cycloalkanes has led to the discovery of seven packing patterns built up from hydrogen-bonded homo- and heterochiral chains of racemic molecules, associated in either antiparallel or parallel arrays [Kálmán et al. (2001). Acta Cryst. B57, 539-550]. Two further patterns have been revealed in the close packing of analogous alicyclic beta-amino acids [Fábián et al. (2005). Cryst. Growth Des. 5, 773-782]. Since each pattern is represented by at least one crystal structure, the chemical similarity and crystallographic forms of these crystals have facilitated the recognition that these patterns differ by one or two rotation(s) of the common motifs (e.g. dimers, tetramers, helices etc.), or the whole pattern may rotate through 180 degrees in an oblique unit cell. Such non-crystallographic--with the exception of polymorphism--virtual rotations as a whole may be denoted by the expression morphotropism. According to Kitaigorodskii [(1961), Organic Chemical Crystallography, pp. 222-231. New York: Consultants Bureau], morphotropism is an attempt to keep the packing coefficient above 0.6 whenever there are alternative possibilities for the structures of closely related molecules. It has been found that crystals of stereoisomers are also frequently related by such virtual rotations. Similarly, non-crystallographic rotations effect bridges between homostructural crystals [Kálmán et al. (1993b). Acta Cryst. B49, 1039-1049] and occasionally hallmark the polymorphism of organic compounds [Kálmán et al. (2003) J. Am. Chem. Soc. 125, 34-35]. In polymorphs, however, such rotations really transform one molecule into another in order to achieve a better packing mediated by solvents, temperature etc.

  15. Comment on "Investigations of interstitial generations near growth interface depending on crystal pulling rates during CZ silicon growth by detaching from the melt" by T. Abe et al. [J. Cryst. Growth 434 (2016) 128-137] and on "Observations of secondary defects and vacancies in CZ silicon crystals detached from melt using four different types of characterization technique" by T. Abe et al. [J. Cryst. Growth 436 (2016) 23-33

    NASA Astrophysics Data System (ADS)

    Vanhellemont, Jan; Kamiyama, Eiji; Nakamura, Kozo; Sueoka, Koji

    2016-09-01

    In the papers mentioned above, Abe et al. published beautiful experimental data on intrinsic point defect related defect distributions in detached growing Czochralski Si crystals with and without additional thermal anneals [1,2]. The new fact compared to the results published before [3] is that the crystals are pulled with decreasing speed before detaching, resulting in crystals that vary along the axis from initially vacancy-rich to interstitial-rich for the slowest pulling speed before detaching.

  16. Mechanism of amorphous silica particles precipitation: simulation approach compared to experimental results

    NASA Astrophysics Data System (ADS)

    Noguera, Claudine; Fritz, Bertrand; Clement, Alain

    2015-04-01

    Despite its importance in numerous industrial and natural processes, many unsolved questions remain regarding the mechanism of silica precipitation in aqueous solutions: order of the reaction, role of silica oligomers, existence of an induction time and characteristics of the particle population. Beyond empirical approaches used in the past, we demonstrate that the classical nucleation theory associated to a size dependent growth law, as embedded in the NANOKIN code (1-3), allows a quantitative description of precipitation occurring under largely different experimental conditions : preexisting initial supersaturation in a large domain of temperature (5-150°C) and chemical composition (4), supersaturation reached by neutralization of a high pH silica solution (5) or by fast cooling (6). In that way, the mechanism of silica precipitation can be unraveled. We are able to discard the hypothesis of an induction time as an explanation for the plateaus observed in the saturation curves in these experiments. We challenge the role of oligomer incorporation at the growth stage to account for the observed rate laws and we stress the difference between the order of the growth law and the order of the total reaction rate. We also demonstrate that the characteristics of the particle population are strongly dependent on the way supersaturation is reached (7). Such a microscopic approach thus proves to be well suited to elucidate the mechanism of nanoparticle formation in natural and industrial contexts, involving silica, but also other mineral phases produced as nanoparticles (8). (1) Noguera C., Fritz B., Clément A. and Barronet A., J. Cryst. Growth, 2006, 297, 180. (2) Noguera C., Fritz B., Clément A. and Barronet A., J. Cryst. Growth, 2006, 297, 187. (3) Fritz B., Clément A., Amal Y. and Noguera C., Geochim. Cosmochim. Acta, 2009, 73, 1340. (4) Rothbaum, H.P. and Rohde A.G., J. Colloid Interf. Sci., 1979,71, 533. (5) Tobler D.J., Shaw S. and Benning L.G., Geochim

  17. Second monoclinic form of (E)-3-(4-fluoro­phen­yl)-1-phenyl­prop-2-en-1-one

    PubMed Central

    Arias-Ruiz, Saira N.; Romero, Nancy; Lobato-García, Carlos E.; Gómez-Rivera, Abraham; Mendoza, Angel

    2013-01-01

    The unit-cell dimensions and space group of the second monoclinic polymorph of the title compound, C15H11FO, differ from those of the previously reported form [Jing (2009 ▶). Acta Cryst. E65, o2515]. The title compound shows an E conformation of the C=C bond with the 4-fluoro­phenyl group opposite to the benzoyl group. The torsion angle of between the planes of the 4-fluoro­phenyl and benzoyl groups is 10.53 (6)°. In the crystal, weak C—H⋯O and C—H⋯F inter­actions form a cross-linked packing motif, building sheets parallel to (-102). PMID:24454121

  18. Crystal structure of bis­(2-amino-5-chloro­pyridinium) tetra­chlorido­cobaltate(II)

    PubMed Central

    Mghandef, Marwa; Boughzala, Habib

    2015-01-01

    The title salt, (C5H6ClN2)2[CoCl4], was synthesized by slow evaporation of an aqueous solution at room temperature. The asymmetric unit consists of two essentially planar (C5H6ClN2)+ cations [maximum deviations = 0.010 (3) and 0.014 (3) Å] that are nearly perpendicular to each other [dihedral angle = 84.12 (7)°]. They are bonded through N—H⋯Cl hydrogen bonds to distorted [CoCl4]2− tetra­hedra, leading to the formation of undulating layers parallel to (100). The structure is isotypic with the Zn analogue [Kefi et. al (2011). Acta Cryst. E67, m355–m356.] PMID:25995878

  19. Properties of X-ray resonant scattering in the Bragg case revealed on the Riemann surface.

    PubMed

    Saka, Takashi

    2016-07-01

    Continuing the work described in the previous paper [Saka (2016). Acta Cryst. A72, 338-348], the dynamical theory for perfect crystals in the Bragg case is reformulated using the Riemann surface. In particular, diffraction under resonant scattering conditions is investigated. The characteristic features of the dispersion surface and the rocking curve are analytically revealed using four parameters, which are the real and imaginary parts of two quantities specifying the degree of departure from the exact Bragg conditions and the reflection strength. Characteristic properties that have been deduced through numerical analysis are derived analytically using these four parameters. Visualization of the geometric relationships between the four parameters on the Riemann surface is useful for understanding many properties such as symmetry and sharpness of the rocking curve under special conditions. Therefore, employing the Riemann surface is instructive for numerical analysis and useful for understanding dynamical diffraction in the Bragg case. PMID:27357849

  20. Structure refinement using precession electron diffraction tomography and dynamical diffraction: tests on experimental data.

    PubMed

    Palatinus, Lukáš; Corrêa, Cinthia Antunes; Steciuk, Gwladys; Jacob, Damien; Roussel, Pascal; Boullay, Philippe; Klementová, Mariana; Gemmi, Mauro; Kopeček, Jaromír; Domeneghetti, M Chiara; Cámara, Fernando; Petříček, Václav

    2015-12-01

    The recently published method for the structure refinement from three-dimensional precession electron diffraction data using dynamical diffraction theory [Palatinus et al. (2015). Acta Cryst. A71, 235-244] has been applied to a set of experimental data sets from five different samples - Ni2Si, PrVO3, kaolinite, orthopyroxene and mayenite. The data were measured on different instruments and with variable precession angles. For each sample a reliable reference structure was available. A large series of tests revealed that the method provides structure models with an average error in atomic positions typically between 0.01 and 0.02 Å. The obtained structure models are significantly more accurate than models obtained by refinement using kinematical approximation for the calculation of model intensities. The method also allows a reliable determination of site occupancies and determination of absolute structure. Based on the extensive tests, an optimal set of the parameters for the method is proposed.

  1. 2-Hy­droxy-3-meth­oxy­benzaldehyde (o-vanillin) revisited

    PubMed Central

    Shin, David; Müller, Peter

    2012-01-01

    The structure of ortho-vanillin, C8H8O3, has been revisited with modern methods and at low temperature (100 K). The previous structure [Iwasaki et al. (1976 ▶). Acta Cryst. B32, 1264–1266] is confirmed, but geometric precision is improved by an order of magnitude. The C atom of the meth­oxy group lies close to the benzene ring plane, which is the most common geometry for –OMe groups lying ortho to –OH groups on an aromatic ring. The crystal structure displays one intra­molecular O—H⋯O and three weak inter­molecular C—H⋯O hydrogen bonds. PMID:22904806

  2. Redetermination of (NH4)2HAsO4

    PubMed Central

    Weil, Matthias

    2012-01-01

    In comparison with the original determination based on Weissenberg film data [Khan et al. (1970 ▶). Acta Cryst. B26, 1889–1892], the current redetermination of diammonium hydrogenarsenate(V) reveals all atoms with anisotropic displacement parameters and all H atoms localized. This allowed an unambiguous assignment of the hydrogen-bonding pattern, which is similar to that of the isotypic phosphate analogue (NH4)2HPO4. The structure of the title compound consists of slightly distorted AsO3(OH) and NH4 tetra­hedra, linked into a three-dimensional structure by an extensive network of O—H⋯O and N—H⋯O hydrogen bonds. PMID:23284312

  3. Redetermination of AgPO3

    PubMed Central

    Terebilenko, Katherina V.; Zatovsky, Igor V.; Ogorodnyk, Ivan V.; Baumer, Vyacheslav N.; Slobodyanik, Nikolay S.

    2011-01-01

    Single crystals of silver(I) polyphosphate(V), AgPO3, were prepared via a phospho­ric acid melt method using a solution of Ag3PO4 in H3PO4. In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ▶). Acta Cryst. 14, 779–784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO5] polyhedra, giving rise to multidirectional ribbons, and from two types of PO4 tetra­hedra linked into meandering chains (PO3)n spreading parallel to the b axis with a repeat unit of four tetra­hedra. The calculated bond-valence sum value of one of the two AgI ions indicates a significant strain of the structure. PMID:21522230

  4. Redetermination of AgPO(3).

    PubMed

    Terebilenko, Katherina V; Zatovsky, Igor V; Ogorodnyk, Ivan V; Baumer, Vyacheslav N; Slobodyanik, Nikolay S

    2011-02-09

    Single crystals of silver(I) polyphosphate(V), AgPO(3), were prepared via a phospho-ric acid melt method using a solution of Ag(3)PO(4) in H(3)PO(4). In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ▶). Acta Cryst. 14, 779-784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO(5)] polyhedra, giving rise to multidirectional ribbons, and from two types of PO(4) tetra-hedra linked into meandering chains (PO(3))(n) spreading parallel to the b axis with a repeat unit of four tetra-hedra. The calculated bond-valence sum value of one of the two Ag(I) ions indicates a significant strain of the structure.

  5. A redetermination from the original data of the crystal structure of 2-amino-4,6-di-meth-oxy-pyrimidin-1-ium 4-amino-benzoate.

    PubMed

    Fábry, Jan

    2016-04-01

    The title structure, C6H9.5N3O2 (0.5+)·C7H6.5NO2 (0.5-), which might be named schematically as 2-amino-4,6-di-meth-oxy-pyrimidine-(μ2-hydrogen)-4-amino-benzoate to indicate a bridging H atom, has been redetermined from the data published by Thanigaimani, Mu-thiah & Lynch [Acta Cryst. (2006), E62, o2976-o2978]. The improvement of the present redetermination consists in a released geometry of the primary amine groups, which were originally assumed to be planar, as well as in a redetermination of the position of the hy-droxy H atom. This H atom, whose parameters were originally constrained, turns out to be situated about the centre of the O⋯N hydrogen bond in two disordered positions with occupancies of 0.5 each. PMID:27375878

  6. Structure of Physarum polycephalum cytochrome b 5 reductase at 1.56 Å resolution

    PubMed Central

    Kim, Sangwoo; Suga, Michihiro; Ogasahara, Kyoko; Ikegami, Terumi; Minami, Yoshiko; Yubisui, Toshitsugu; Tsukihara, Tomitake

    2007-01-01

    Physarum polycephalum cytochrome b 5 reductase catalyzes the reduction of cytochrome b 5 by NADH. The structure of P. polycephalum cytochrome b 5 reductase was determined at a resolution of 1.56 Å. The molecular structure was compared with that of human cytochrome b 5 reductase, which had previously been determined at 1.75 Å resolution [Bando et al. (2004 ▶), Acta Cryst. D60, 1929–1934]. The high-resolution structure revealed conformational differences between the two enzymes in the adenosine moiety of the FAD, the lid region and the linker region. The structural properties of both proteins were inspected in terms of hydrogen bonding, ion pairs, accessible surface area and cavity volume. The differences in these structural properties between the two proteins were consistent with estimates of their thermostabilities obtained from differential scanning calorimetry data. PMID:17401193

  7. Crystal structure of bis­[tetra­kis­(tri­phenyl­phosphane-κP)silver(I)] (nitrilo­tri­acetato-κ4 N,O,O′,O′′)(tri­phenyl­phosphane-κP)argentate(I) with an unknown amount of methanol as solvate

    PubMed Central

    Noll, Julian; Korb, Marcus; Lang, Heinrich

    2016-01-01

    The structure of the title compound, [Ag(C18H15P)4]2[Ag(C6H6NO6)(C18H15P)], exhibits trigonal (P-3) symmetry, with a C 3 axis through all three complex ions, resulting in an asymmetric unit that contains one third of the atoms present in the formula unit. The formula unit thus contains two of the cations, one anion and disordered mol­ecules of methanol as the packing solvent. Attempts to refine the solvent model were unsuccessful, indicating uninter­pretable disorder. Thus, the SQUEEZE procedure in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9–18] was applied, accounting for 670 electrons per unit cell, representing approximately 18 mol­ecules of methanol in the formula unit. The stated crystal data for M r, μ etc do not take these into account. PMID:27006796

  8. Crystal structure of 4-(tri­methyl­germ­yl)benzoic acid

    PubMed Central

    Knauer, Lena; Barth, Eva R.; Golz, Christopher; Strohmann, Carsten

    2015-01-01

    The title compound, [Ge(CH3)3(C7H5O2)], was obtained as a by-product in the synthesis of the corresponding aldehyde. Two slightly different mol­ecules are present in the asymmetric unit. In both mol­ecules, the geometry of the aromatic ring plane is distorted by varying intensities. Additionally, the Ge atoms deviate from the mean aromatic ring planes. Whereas the distance of the Ge atom to the ring plane is only 0.101 (4) Å in the first mol­ecule, this distance is increased to 0.210 (4) Å in the second. In the crystal structure, centrosymmetric O—H⋯O hydrogen-bonded dimers are formed. The title compound is isostructural with the Si analogue [Haberecht et al. (2004 ▸). Acta Cryst. E60, o329–0330]. PMID:26090151

  9. 2,2′-(1,3-Diazinane-1,3-di­yl)diaceto­nitrile: a second monoclinic polymorph

    PubMed Central

    Rivera, Augusto; Maldonado, Mauricio; Ríos-Motta, Jaime; Fejfarová, Karla; Dušek, Michal

    2011-01-01

    A new monoclinic polymorph of the title compound, C8H12N4, in the space group P21/n (Z = 4) is reported. The previously known form was also monoclinic, P21 /c (Z = 4), but the unit-cell parameters and crystal packing were different [Shoja & Saba (1993 ▶). Acta Cryst. C49, 354–355]. The hexa­hydro­pyrimidine ring of the title compound adopts a chair conformation with a diequatorial substitution and with the CH2-C N groups oriented nearly parallel and in the same direction [NC—CH2⋯CH2—CN pseudo torsion angle = −6.27 (18)°]. In the crystal, inter­molecular C—H⋯ N hydrogen bonds connects the mol­ecules into a chain along the b axis. PMID:22065712

  10. Crystal structure of 2,4-bis­(2-chloro­phen­yl)-7-tert-pent­yl-3-aza­bicyclo[3.3.1]nonan-9-one

    PubMed Central

    Park, Dong Ho; Ramkumar, V.; Parthiban, P.

    2014-01-01

    The title compound, C25H29Cl2NO, which is a chloro analog of 2,4-bis­(2-bromo­phen­yl)-7-(tert-pent­yl)-3-aza­bicyclo­[3.3.1]nonan-9-one [Park, Ramkumar & Parthiban (2012). Acta Cryst. E68, o2946], exists in a twin-chair conformation with an equatorial orientation of the 2-chloro­phenyl groups. The tert-pentyl group on the cyclo­hexa­none adopts an exocyclic equatorial position and is disordered between two orientations in a ratio 0.520 (8):0.480 (8). The crystal packing shows no directional contacts beyond van der Waals contacts. PMID:25484804

  11. A second polymorph of sodium di­hydrogen citrate, NaH2C6H5O7: structure solution from powder diffraction data and DFT comparison

    PubMed Central

    Rammohan, Alagappa; Kaduk, James A.

    2016-01-01

    The crystal structure of a second polymorph of sodium di­hydrogen citrate, Na+·H2C6H5O7 −, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The powder pattern of the commercial sample used in this study did not match that corresponding to the known crystal structure [Glusker et al. (1965). Acta Cryst. 19, 561–572; refcode NAHCIT]. In this polymorph, the [NaO7] coordination polyhedra form edge-sharing chains propagating along the a axis, while in NAHCIT the octa­hedral [NaO6] groups form edge-sharing pairs bridged by two hy­droxy groups. The most notable difference is that in this polymorph one of the terminal carboxyl groups is deprotonated, while in NAHCIT the central carboxyl­ate group is deprotonated, as is more typical. PMID:27308058

  12. An alternative empirical model for the relationship between the bond valence and the thermal expansion rate of chemical bonds.

    PubMed

    Sidey, Vasyl

    2015-08-01

    The relationship between the bond valence s and the thermal expansion rate of chemical bonds (dr/dT) has been closely approximated by using the alternative three-parameter empirical model (dr/dT) = (u + vs)(-1/w), where u, v and w are the refinable parameters. Unlike the s-(dr/dT) model developed by Brown et al. [(1997), Acta Cryst. B53, 750-761], this alternative model can be optimized for particular s-(dr/dT) datasets in the least-squares refinement procedure. For routine calculations of the thermal expansion rates of chemical bonds, the alternative model with the parameters u = -63.9, v = 2581.0 and w = 0.647 can be recommended.

  13. Redetermined crystal structure of N-(β-carb-oxy-eth-yl)-α-isoleucine.

    PubMed

    Chandrarekha, M; Srinivasan, N; Krishnakumar, R V

    2015-09-01

    Redetermination of the crystal structure of N-(β-carb-oxy-eth-yl)-α-isoleucine, C9H18N2O3, reported earlier by Nehls et al. [Acta Cryst. (2013), E69, o172-o173], was undertaken in which the ionization state assigned to the mol-ecule as unionized has been modified as zwitterionic in the present work. Single-crystal X-ray intensity data obtained from freshly grown crystals and freely refining the amino H atoms provide enhanced refinement and structural parameters, particularly the hydrogen-bonding scheme. N-H⋯O hydrogen bonds dominate the inter-molecular inter-actions along with a C-H⋯O hydrogen bond. The inter-molecular inter-action pattern is a three-dimensional network. The structure was refined as a two-component perfect inversion twin. PMID:26396893

  14. Redetermination of (NH(4))(2)HAsO(4).

    PubMed

    Weil, Matthias

    2012-11-01

    In comparison with the original determination based on Weissenberg film data [Khan et al. (1970 ▶). Acta Cryst. B26, 1889-1892], the current redetermination of diammonium hydrogenarsenate(V) reveals all atoms with anisotropic displacement parameters and all H atoms localized. This allowed an unambiguous assignment of the hydrogen-bonding pattern, which is similar to that of the isotypic phosphate analogue (NH(4))(2)HPO(4). The structure of the title compound consists of slightly distorted AsO(3)(OH) and NH(4) tetra-hedra, linked into a three-dimensional structure by an extensive network of O-H⋯O and N-H⋯O hydrogen bonds.

  15. Crystal structure of bis-{1-[(E)-(2-meth-oxy-phen-yl)diazen-yl]naphthalen-2-olato-κ(3) O,N (2),O'}copper(II) containing an unknown solvate.

    PubMed

    Chetioui, Souheyla; Hamdouni, Noudjoud; Rouag, Djamil-Azzeddine; Bouaoud, Salah Eddine; Merazig, Hocine

    2015-11-01

    The title complex, [Cu(C17H13N2O2)2], crystallizes with two independent mol-ecules in the asymmetric unit. Each Cu(II) atom has a distorted ocahedral coordination environment defined by two N atoms and four O atoms from two tridentate 1-[(E)-(2-meth-oxy-phen-yl)diazen-yl]naphthalen-2-olate ligands. In the crystal, the two mol-ecules are linked via weak C-H⋯O hydrogen bonds which in turn stack parallel to [010]. A region of disordered electron density, most probably disordered methanol solvent molecules, was corrected for using the SQUEEZE routine in PLATON [Spek (2015). Acta Cryst. C71, 9-18]. Their formula mass and unit-cell characteristics were not taken into account during refinement.

  16. Crystal structure of bis-[tetra-kis-(tri-phenyl-phosphane-κP)silver(I)] (nitrilo-tri-acetato-κ(4) N,O,O',O'')(tri-phenyl-phosphane-κP)argentate(I) with an unknown amount of methanol as solvate.

    PubMed

    Noll, Julian; Korb, Marcus; Lang, Heinrich

    2016-03-01

    The structure of the title compound, [Ag(C18H15P)4]2[Ag(C6H6NO6)(C18H15P)], exhibits trigonal (P-3) symmetry, with a C 3 axis through all three complex ions, resulting in an asymmetric unit that contains one third of the atoms present in the formula unit. The formula unit thus contains two of the cations, one anion and disordered mol-ecules of methanol as the packing solvent. Attempts to refine the solvent model were unsuccessful, indicating uninter-pretable disorder. Thus, the SQUEEZE procedure in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18] was applied, accounting for 670 electrons per unit cell, representing approximately 18 mol-ecules of methanol in the formula unit. The stated crystal data for M r, μ etc do not take these into account.

  17. Crystal structure of [(E)-({2-[3-(2-{(1E)-[(carbamo-thioyl-amino)-imino]-meth-yl}phen-oxy)prop-oxy]phen-yl}methyl-idene)amino]-thio-urea with an unknown solvate.

    PubMed

    Mague, Joel T; Mohamed, Shaaban K; Akkurt, Mehmet; Younes, Sabry H H; Albayati, Mustafa R

    2015-07-01

    The title mol-ecule, C19H22N6O2S2, has crystallographically imposed C 2 symmetry, with the central C atom lying on the rotation axis. The O-C-C-C torsion angle for the central chain is -59.22 (16)° and the dihedral angle between the planes of the benzene rings is 75.20 (7)°. In the crystal, N-H⋯O and N-H⋯S inter-actions link the mol-ecules, forming a three-dimensional network encompassing channels running parallel to the c axis, which account for about 20% of the unit-cell volume. The contribution to the scattering from the highly disordered solvent mol-ecules in these channels was removed with the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9-18] in PLATON. The stated crystal data for M r, μ etc. do not take these into account.

  18. A second monoclinic polymorph of N-(2,4-dinitro­phen­yl)-2,4-dinitro­aniline

    PubMed Central

    Tokutome, Yui; Okuno, Tsunehisa

    2013-01-01

    The title compound, C12H7N5O8, was previously described in space group P21/n with Z = 4 [Wu et al. (2007 ▶). Acta Cryst. E63, o4194]. The current monoclinic P21/c polymorph was obtained from a mixed solution of dichloro­methane and hexane. The dihedral angle between the benzene rings is 44.16 (5)°, smaller than in the previously reported polymorph [56.3 (2)°]. As a result of the steric hinderance of the nitro groups, hydrogen bonding is limited intramolecularly. The dihedral angles between the phenyl rings and their attached nitro groups are 18.97 (6) and 17.71 (5)° at the 2-position, and 18.52 (6) and 32.41 (6)° at the 4-position. PMID:23424444

  19. About the hybrid Fourier syntheses: a probabilistic approach.

    PubMed

    Burla, Maria Cristina; Carrozzini, Benedetta; Cascarano, Giovanni Luca; Giacovazzo, Carmelo; Polidori, Giampiero

    2011-09-01

    The difference electron density has recently been revisited via the method of joint probability distribution functions [Burla et al. (2010). Acta Cryst. A 66, 347-361]. New Fourier coefficients were devised which were the basis of a new ab initio method for the solution of the phase problem (i.e. VLD, vive la difference). In this paper we study the joint probability distribution functions P(F, F(p), F(Q)), where F(Q) is the structure factor corresponding to the ideal hybrid Fourier synthesis ρ(Q) = τρ - ωρ(p) and τ and ω are any pair of real numbers. New Fourier coefficients for the calculations of any hybrid synthesis are obtained, and the properties of the corresponding electron-density maps are discussed. The first applications show the correctness of our theoretical approach and suggest possible applications in phasing procedures. PMID:21844649

  20. Simulations of Kikuchi patterns due to thermal diffuse scattering on MgO crystals.

    PubMed

    Omoto, Kazuya; Tsuda, Kenji; Tanaka, Michiyoshi

    2002-01-01

    Inelastic scattering of fast transmission electrons from a perfect crystal is investigated using the Bloch wave theory. A comprehensive expression for the scattering of electrons is given, which includes both elastic and inelastic multiple scatterings. This expression is an extended form of Fujimoto's expression for elastic scattering (J. Phys. Soc. Japan 14:1558 (1959)). For the approximation of single inelastic scattering, the expression becomes equivalent to the formula of Rez et al. (Phil. Mag. 35: 81 (1977)). When thermal diffuse scattering (TDS) is considered using the Einstein model or the scattering factor for TDS given by Hall and Hirsch (Proc. R. Soc. A 286: 158 (1965)), Rossouw and Bursill's expression (Acta Cryst. A 41: 320 (1985)) is derived. This expression has been used in computer simulations of TDS intensity distribution (Kikuchi pattern). It is shown that the simulations for magnesium oxide (MgO) using 357 beams agree quite well with the experimental ones.

  1. Aripiprazole salts. II. Aripiprazole perchlorate.

    PubMed

    Freire, Eleonora; Polla, Griselda; Baggio, Ricardo

    2012-06-01

    The molecular structure of aripiprazole perchlorate (systematic name: 4-(2,3-dichlorophenyl)-1-{4-[(2-oxo-1,2,3,4-tetrahydroquinolin-7-yl)oxy]butyl}piperazin-1-ium perchlorate), C(23)H(28)Cl(2)N(3)O(2)(+)·ClO(4)(-), does not differ substantially from the recently published structure of aripiprazole nitrate [Freire, Polla & Baggio (2012). Acta Cryst. C68, o170-o173]. Both compounds have almost identical bond distances, bond angles and torsion angles. The two different counter-ions occupy equivalent places in the two structures, giving rise to very similar first-order `packing motifs'. However, these elemental arrangements interact with each other in different ways in the two structures, leading to two-dimensional arrays with quite different organizations.

  2. Crystal structure of bis-[tetra-kis-(tri-phenyl-phosphane-κP)silver(I)] (nitrilo-tri-acetato-κ(4) N,O,O',O'')(tri-phenyl-phosphane-κP)argentate(I) with an unknown amount of methanol as solvate.

    PubMed

    Noll, Julian; Korb, Marcus; Lang, Heinrich

    2016-03-01

    The structure of the title compound, [Ag(C18H15P)4]2[Ag(C6H6NO6)(C18H15P)], exhibits trigonal (P-3) symmetry, with a C 3 axis through all three complex ions, resulting in an asymmetric unit that contains one third of the atoms present in the formula unit. The formula unit thus contains two of the cations, one anion and disordered mol-ecules of methanol as the packing solvent. Attempts to refine the solvent model were unsuccessful, indicating uninter-pretable disorder. Thus, the SQUEEZE procedure in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18] was applied, accounting for 670 electrons per unit cell, representing approximately 18 mol-ecules of methanol in the formula unit. The stated crystal data for M r, μ etc do not take these into account. PMID:27006796

  3. Crystal structure of bis-{1-[(E)-(2-meth-oxy-phen-yl)diazen-yl]naphthalen-2-olato-κ(3) O,N (2),O'}copper(II) containing an unknown solvate.

    PubMed

    Chetioui, Souheyla; Hamdouni, Noudjoud; Rouag, Djamil-Azzeddine; Bouaoud, Salah Eddine; Merazig, Hocine

    2015-11-01

    The title complex, [Cu(C17H13N2O2)2], crystallizes with two independent mol-ecules in the asymmetric unit. Each Cu(II) atom has a distorted ocahedral coordination environment defined by two N atoms and four O atoms from two tridentate 1-[(E)-(2-meth-oxy-phen-yl)diazen-yl]naphthalen-2-olate ligands. In the crystal, the two mol-ecules are linked via weak C-H⋯O hydrogen bonds which in turn stack parallel to [010]. A region of disordered electron density, most probably disordered methanol solvent molecules, was corrected for using the SQUEEZE routine in PLATON [Spek (2015). Acta Cryst. C71, 9-18]. Their formula mass and unit-cell characteristics were not taken into account during refinement. PMID:26594536

  4. Crystal structure of benzene-1,3,5-tri­carb­oxy­lic acid–4-pyridone (1/3)

    PubMed Central

    Staun, Selena L.; Oliver, Allen G.

    2015-01-01

    Slow co-crystallization of a solution of benzene-1,3,5-tri­carb­oxy­lic acid with a large excess of 4-hy­droxy­pyridine produces an inter­penetrating, three-dimensional, hydrogen-bonded framework consisting of three 4-pyridone and one benzene-1,3,5-tri­carb­oxy­lic acid mol­ecules, C9H6O6·3C5H5NO. This structure represents an ortho­rhom­bic polymorph of the previously reported C-centered, monoclinic structure [Campos-Gaxiola et al. (2014 ▸). Acta Cryst. E70, o453–o454]. PMID:26594492

  5. Redetermination of the borax structure from laboratory X-ray data at 145 K.

    PubMed

    Gainsford, Graeme J; Kemmitt, Tim; Higham, Caleb

    2008-04-23

    THE TITLE COMPOUND, SODIUM TETRABORATE DECAHYDRATE (MINERAL NAME: borax), Na(2)[B(4)O(5)(OH)(4)]·8H(2)O, has been studied previously using X-ray [Morimoto (1956). Miner. J.2, 1-18] and neutron [Levy & Lisensky (1978). Acta Cryst. B34, 3502-3510] diffraction data. The structure contains tetra-borate anions [B(4)O(5)(OH)(4)](2-) with twofold rotation symmetry, which form hydrogen-bonded chains, and [Na(H(2)O)(6)] octa-hedra that form zigzag chains [Na(H(2)O)(4/2)(H(2)O)(2/1)]. The O-H bond distances obtained from the present redetermination at 145 K are shorter than those in the neutron study by an average of 0.127 (19) Å.

  6. Redetermination of 3-deaza­uracil

    PubMed Central

    Portalone, Gustavo

    2008-01-01

    The crystal structure of the title compound, 4-hydr­oxy-2-pyridone, C5H5NO2, which has been the subject of several determinations using X-rays and neutron diffraction, was first reported by Low & Wilson [Acta Cryst. (1983). C39, 1688–1690]. It has been redetermined, providing a significant increase in the precision of the derived geometric parameters. The asymmetric unit comprises a planar 4-enol tautomer having some degree of delocalization of π-electron density through the mol­ecule. In the crystal structure, the mol­ecules are connected into chains by two strong O—H⋯O and N—H⋯O hydrogen bonds between the OH and NH groups and the carbonyl O atom. PMID:21202619

  7. Crystal structure of [(E)-({2-[3-(2-{(1E)-[(carbamo-thioyl-amino)-imino]-meth-yl}phen-oxy)prop-oxy]phen-yl}methyl-idene)amino]-thio-urea with an unknown solvate.

    PubMed

    Mague, Joel T; Mohamed, Shaaban K; Akkurt, Mehmet; Younes, Sabry H H; Albayati, Mustafa R

    2015-07-01

    The title mol-ecule, C19H22N6O2S2, has crystallographically imposed C 2 symmetry, with the central C atom lying on the rotation axis. The O-C-C-C torsion angle for the central chain is -59.22 (16)° and the dihedral angle between the planes of the benzene rings is 75.20 (7)°. In the crystal, N-H⋯O and N-H⋯S inter-actions link the mol-ecules, forming a three-dimensional network encompassing channels running parallel to the c axis, which account for about 20% of the unit-cell volume. The contribution to the scattering from the highly disordered solvent mol-ecules in these channels was removed with the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9-18] in PLATON. The stated crystal data for M r, μ etc. do not take these into account. PMID:26279946

  8. Refinement of crystal structural parameters and charge density using convergent-beam electron diffraction--the rhombohedral phase of LaCrO3.

    PubMed

    Tsuda, Kenji; Ogata, Yoichiro; Takagi, Kazunari; Hashimoto, Takuya; Tanaka, Michiyoshi

    2002-11-01

    Atom positions and anisotropic Debye-Waller factors of the rhombohedral phase of LaCrO(3) have been refined simultaneously with the low-order structure factors, using a structure-analysis method of convergent-beam electron diffraction (CBED) proposed by Tsuda & Tanaka [Acta Cryst. (1999), A55, 939-954]. The method is based on the least-squares fitting between full dynamical calculations and energy-filtered intensities of two-dimensional higher-order Laue-zone (HOLZ) and zeroth-order Laue-zone (ZOLZ) CBED patterns. The positions of the oxygen atoms have been determined with a high precision. Clear anisotropy of the thermal vibrations of the oxygen atoms has been successfully determined by the CBED method for the first time. The charge transfer from the La and Cr atoms to the O atoms has been found from the deformation charge-density map.

  9. Icosahedral quasiperiodic packing of fibres parallel to fivefold and threefold axes.

    PubMed

    Audier, M; Duneau, M

    2000-01-01

    Building rules are examined for an icosahedral quasiperiodic packing of fibres with axes parallel to the ten threefold axes, first employing an experimental construction and afterwards a mathematical demonstration using the cut-and-project method applied in hyperspace. As a result of this latter approach, very simple two-dimensional (2D) building rules are proposed. Similar simple 2D rules have also been proposed for the case of an icosahedral quasiperiodic packing with fibre axes parallel to the six fivefold axes [Duneau & Audier (1999). Acta Cryst. A55, 746-754]. Finally, the construction of another icosahedral quasiperiodic packing resulting from a combination of two groups of fibres respectively parallel to six fivefold and ten threefold axes is reported. A brief discussion is given on different particular mechanical behaviours which might a priori be expected from the various enantiomorphic properties of these packings.

  10. Redetermination of AgPO(3).

    PubMed

    Terebilenko, Katherina V; Zatovsky, Igor V; Ogorodnyk, Ivan V; Baumer, Vyacheslav N; Slobodyanik, Nikolay S

    2011-01-01

    Single crystals of silver(I) polyphosphate(V), AgPO(3), were prepared via a phospho-ric acid melt method using a solution of Ag(3)PO(4) in H(3)PO(4). In comparison with the previous study based on single-crystal Weissenberg photographs [Jost (1961 ▶). Acta Cryst. 14, 779-784], the results were mainly confirmed, but with much higher precision and with all displacement parameters refined anisotropically. The structure is built up from two types of distorted edge- and corner-sharing [AgO(5)] polyhedra, giving rise to multidirectional ribbons, and from two types of PO(4) tetra-hedra linked into meandering chains (PO(3))(n) spreading parallel to the b axis with a repeat unit of four tetra-hedra. The calculated bond-valence sum value of one of the two Ag(I) ions indicates a significant strain of the structure. PMID:21522230

  11. Two new polytypes of 2,4,6-tri­bromo­benzo­nitrile

    PubMed Central

    Britton, Doyle; Noland, Wayland E.; Tritch, Kenneth J.

    2016-01-01

    Three polymorphs of 2,4,6-tri­bromo­benzo­nitrile (RCN), C7H2Br3N, two of which are novel and one of which is a redetermination of the original structure first determined by Carter & Britton [(1972). Acta Cryst. B28, 945–950] are found to be polytypic. Each has a layer structure which differs only in the stacking of the layers. Each layer is composed of mol­ecules associated through C N⋯Br contacts which form R 2 2(10) rings. Two such rings are associated with each N atom; one with each ortho-Br atom. No new polytypes of 1,3,5-tri­bromo-2-iso­cyano­benzene (RNC) were found but a re-determination of the original structure by Carter et al. [(1977). Cryst. Struct. Commun. 6, 543–548] is presented. RNC was found to be isostructural with one of the novel polytypes of RCN. Unit cells were determined for 23 RCN samples and 11 RNC samples. Polytypes could not be distinguished based on crystal habits. In all four structures, each mol­ecule of the asymmetric unit lies across a mirror plane. PMID:26958382

  12. Perspectives on Discourse: Proceedings from the 1998 and 1999 Discourse Symposia at Vaxjo University. Acta Wexionesia, No. 2.

    ERIC Educational Resources Information Center

    Virtanen, Tuija, Ed.; Maricic, Ibolya, Ed.

    2000-01-01

    This volume brings together the majority of lectures and papers presented at the 1998 and 1999 discourse symposia at Vaxjo University. Part one, "Four Perspectives on Discourse," offers a matrix perspective on narrative, a cross cultural perspective on academic rhetoric, a cognitive perspective on informational discourse, and a construction…

  13. Comment on "Apatite: A new redox proxy for silicic magmas?" [Geochimica et Cosmochimica Acta 132 (2014) 101-119

    NASA Astrophysics Data System (ADS)

    Marks, Michael A. W.; Scharrer, Manuel; Ladenburger, Sara; Markl, Gregor

    2016-06-01

    Recently Miles et al. (2014) proposed that a negative correlation between oxygen fugacity (expressed as logfO2 and the Mn content of apatite from a range of intermediate to silicic igneous rocks could be used as an oxybarometer (Eq. (1)).

  14. Crystallization of Chicken Egg White Lysozyme from Sulfate Salts

    NASA Technical Reports Server (NTRS)

    Forsythe, Elizabeth; Pusey, Marc

    1998-01-01

    It has been "known" that chicken egg white lysozyme does not crystallize from sulfate, particularly ammonium sulfate, salts, but instead gives amorphous precipitates. This has been the basis of several studies using lysozyme comparing macromolecule crystal nucleation and amorphous precipitation. Recently Ries-Kautt et al (Acta Cryst D50, (1994) 366) have shown that purified isoionic CEWL could be crystallized from low concentrations of sulfate at basic pH, and we subsequently showed that in fact CEWL could be purified in both the tetragonal and orthorhombic forms using ammonium sulfate over the pH range 4.0 to 7.8 (Acta Cryst D53, (1997) 795). We have now extended these observations to include a range of common sulfate salts, specifically sodium, potassium, rubidium, magnesium, and manganese sulfates. In all cases but the manganese sulfates both the familiar tetragonal and orthorhombic forms were obtained, with unit cell dimensions close to those known for the "classic" sodium chloride crystallized forms. Manganese sulfate has only yielded orthorhombic crystals to date. All crystallizations were carried out using low (typically less than or equal to 6 M) salt and high (greater than approximately 90 mg/ml) protein concentrations. As with ammonium sulfate, the tetragonal - orthorhombic phase shift appears to be a function of both the temperature and the protein concentration, with higher temperatures and concentrations favoring the orthorhombic and lower the tetragonal form. The phase change range is somewhat reduced for the sulfate salts, depending upon conditions being typically between approximately 15 - 20 C. Both the magnesium and manganese sulfates gave crystals at salt concentrations over 0.6 M as well, with magnesium sulfate giving a very slowly nucleating and growing hexagonal form. A triclinic crystal form, characterized by aggressively small crystals (typically 0.1 mm in size) has been occasionally obtained from ammonium sulfate. Finally, preliminary spot

  15. Asymmetric hydrogen bonds in a centrosymmetric environment. III. Quantum mechanical calculations of the potential-energy surfaces for the very short hydrogen bonds in potassium hydrogen dichloromaleate.

    PubMed

    Majerz, I; Olovsson, I

    2007-10-01

    In the crystal structure of potassium hydrogen dichloromaleate there are two short hydrogen bonds of 2.44 A. The 'heavy-atom' structure is centrosymmetric (space group P1) with centers of symmetry in the middle of the O-O bonds, suggesting centered hydrogen bonds. However, earlier unconventional types of refinements of the extensive neutron data taken at 30, 90, 135, 170 and 295 K demonstrated that the H atoms are actually non-centered in the hydrogen bonds, although the environment is centrosymmetric. Traditionally it has been assumed that the hydrogen distribution adopts the same symmetry as the environment. Reviewing these unusual results it was considered of great interest to verify that the non-centered locations of the H atoms are reasonable from an energy point of view. Quantum mechanical calculations have now been carried out for the potential-energy surfaces (PES) for both the centered and non-centered locations of the H atoms. In all cases the non-centered positions are closer to the energy minima in the PES than the centered positions, and this result confirms that the structure is best described with non-centered H atoms. There is virtually perfect agreement between the quantum-mechanically derived reaction coordinates (QMRC) and the bond-order reaction coordinates (BORC) derived using Pauling's bond-order concept together with the principle of conservation of bond order. [Part I: Olovsson et al. (2001). Acta Cryst. B57, 311-316; Part II: Olovsson et al. (2002). Acta Cryst. B58, 627-631.].

  16. Symmetry of semi-reduced lattices.

    PubMed

    Stróż, Kazimierz

    2015-05-01

    The main result of this work is extension of the famous characterization of Bravais lattices according to their metrical, algebraic and geometric properties onto a wide class of primitive lattices (including Buerger-reduced, nearly Buerger-reduced and a substantial part of Delaunay-reduced) related to low-restricted semi-reduced descriptions (s.r.d.'s). While the `geometric' operations in Bravais lattices map the basis vectors into themselves, the `arithmetic' operators in s.r.d. transform the basis vectors into cell vectors (basis vectors, face or space diagonals) and are represented by matrices from the set {\\bb V} of all 960 matrices with the determinant ±1 and elements {0, ±1} of the matrix powers. A lattice is in s.r.d. if the moduli of off-diagonal elements in both the metric tensors M and M(-1) are smaller than corresponding diagonal elements sharing the same column or row. Such lattices are split into 379 s.r.d. types relative to the arithmetic holohedries. Metrical criteria for each type do not need to be explicitly given but may be modelled as linear derivatives {\\bb M}(p,q,r), where {\\bb M} denotes the set of 39 highest-symmetry metric tensors, and p,q,r describe changes of appropriate interplanar distances. A sole filtering of {\\bb V} according to an experimental s.r.d. metric and subsequent geometric interpretation of the filtered matrices lead to mathematically stable and rich information on the Bravais-lattice symmetry and deviations from the exact symmetry. The emphasis on the crystallographic features of lattices was obtained by shifting the focus (i) from analysis of a lattice metric to analysis of symmetry matrices [Himes & Mighell (1987). Acta Cryst. A43, 375-384], (ii) from the isometric approach and invariant subspaces to the orthogonality concept {some ideas in Le Page [J. Appl. Cryst. (1982), 15, 255-259]} and splitting indices [Stróż (2011). Acta Cryst. A67, 421-429] and (iii) from fixed cell transformations to transformations

  17. Reply to "Comment on papers by K. Shanahan that propose to explain anomalous heat generated by cold fusion", E. Storms, Thermochim. Acta (2005)

    SciTech Connect

    Shanahan, Kirk

    2005-09-21

    Dr. E. Storms has published a Letter [1] in which he argues that in a sequence of recent papers [2-5], the apparent excess heat signal claimed by Dr. Shanahan to arise from a calibration constant shift is actually true excess heat. In particular he proposes that the mechanisms proposed that foster the proposed calibration constant shifts [3,5] cannot occur as postulated for several reasons. As well, he proposes Shanahan has ignored the extant data proving this. Because this Letter may lend unwarranted support to acceptance of cold fusion claims, these erroneous arguments used by Storms need to be answered.

  18. [Criminal responsibility in schizophrenia with special attention to the mental state during the criminal act--a study based upon the activation-recurrence phenomenon].

    PubMed

    Higashi, Takahiro

    2009-01-01

    In this article, psychiatric arguments regarding criminal responsibility in schizophrenia are reviewed, and it is pointed out that the arguments have been influenced by the theory of process psychosis. Moreover, two cases judged on the basis of the activation-recurrence phenomenon are exemplified, and fundamental issues are discussed. Investigating the mental state just before the crime helps when deliberating over criminal responsibility. A study of the activation-recurrence phenomenon, conducted by Shinkai and Miyasaka, contributes toward clarifying the recurrence of the micropsychotic state during the criminal act. Generally, schizophrenia is characterized by an alternation between the micropsychotic and basic normal states, and classified clinically into severe, moderate, and mild according to the level of susceptibility to the occurrence of the activation-recurrence phenomenon. Differentiating between the form and contents of the micropsychotic state is of marked importance in schizophrenia. In addition, identifying the form facilitates the distinction between behaviors while sane and those during schizophrenic episodes. Practically, the activating stimuli, which are likely to trigger the micropsychotic state, are applied in the interview to establish the psychiatric testimony based upon the activation-recurrence phenomenon. After the diagnosis of schizophrenia has been confirmed, the examinee is exposed to the stimuli possibly activating the micropsychotic state during the criminal act. Observing the recurrence of the micropsychotic state and its frequency enables estimation of the susceptibility to the occurrence of the activation-recurrence phenomenon and the mental state during the criminal act. Therefore, if a micropsychotic state during the criminal act can be confirmed, the inability to be held legally responsible is postulated. In contrast, if a micropsychotic state during the criminal act cannot be confirmed, the specialist giving the psychiatric testimony should conclude that the crime was most likely undertaken while sane, taking into account the objective circumstantial evidence and the suspect's coherent actions during the crime. Furthermore, in this article, the concept Trugerinnerung, which is a subjective abnormal experience confusing the present and past (a disorganization of memory) is revaluated, and the possibility of concluding that the criminal act was performed with a normal psychology is discussed.

  19. Corrigendum to "In situ produced branched glycerol dialkyl glycerol tetraethers in suspended particulate matter from the Yenisei River, Eastern Siberia" [Geochim. Cosmochim. Acta 125 (2014) 476-491

    NASA Astrophysics Data System (ADS)

    De Jonge, Cindy; Stadnitskaia, Alina; Hopmans, Ellen C.; Cherkashov, Georgy; Fedotov, Andrey; Sinninghe Damsté, Jaap S.

    2015-02-01

    The authors regret some of the information presented in the original article was incorrect. The calculated POC concentrations reported (Table 2) are a factor 100 too high. Consequently, the POC-normalized lipid concentrations (Table 4) are a factor 100 too low. Below, we report the corrected Tables 2 and 4 (corrected values are indicated in bold).

  20. Curriculum Perspectives: Challenges for the Future. Proceedings of a Binational Symnposium = Perspectivas curriculares: Retos para el futuro. Actas del simposio binacional (Austin, Texas, November 9-10, 1994).

    ERIC Educational Resources Information Center

    Southwest Educational Development Lab., Austin, TX.

    This proceedings, in English and Spanish, describes the first U.S./Mexico Curriculum Symposium, held in Austin, Texas, in November 1994. The symposium grew out of an ongoing exchange between educators in the Republic of Mexico and the United States and was attended by over 200 teachers, administrators, staff from state and regional education…

  1. Reply to comment by Marks et al. (2016) on "Apatite: A new redox proxy for silicic magmas?" [Geochimica et Cosmochimica Acta 132 (2014) 101-119

    NASA Astrophysics Data System (ADS)

    Miles, Andrew; Graham, Colin; Hawkesworth, Chris; Gillespie, Martin; Hinton, Richard; Bromiley, Geoffrey

    2016-06-01

    Marks et al. (2016) investigate the applicability of the Mn-in-apatite oxybarometer proposed by Miles et al. (2014) across a range of magma compositions using published data on well-characterised samples. The authors show that for magma compositions outside of the calc-alkaline and intermediate to silicic range used in the preliminary calibration, fO2 values calculated from Mn-in-apatite vary significantly from independently constrained estimates. These data are used to reiterate our warnings that other controls that are additional to oxygen fugacity are likely to affect Mn partitioning into apatite in some rock types, and particularly so in magmas that lie outside of the range of compositions and conditions used in the calibration. Marks et al. (2016) highlight that temperature may have an especially important effect on Mn partitioning in apatite in some rock types.

  2. Corrigendum to "Occurrence and abundance of 6-methyl branched glycerol dialkyl glycerol tetraethers in soils: Implications for palaeoclimate reconstruction" [Geochim. Cosmochim. Acta 141 (2014) 97-112

    NASA Astrophysics Data System (ADS)

    De Jonge, Cindy; Hopmans, Ellen C.; Zell, Claudia I.; Kim, Jung-Hyun; Schouten, Stefan; Sinninghe Damsté, Jaap S.

    2016-06-01

    The authors regret that the r2 values (squared pearson correlation coefficient values) reported in Figs. 7 and 8 and in the text, are instead the non-squared r values. This has no direct influence on our interpretation. We have included the corrected Figs. 7 and 8. The text describing these results should read as follows:

  3. Experimental determination of optimal root-mean-square deviations of macromolecular bond lengths and angles from their restrained ideal values.

    PubMed

    Tickle, Ian J

    2007-12-01

    A number of inconsistencies are apparent in the recent research paper by Jaskolski et al. [(2007), Acta Cryst. D63, 611-620] concerning their recommendations for the values of the magnitude and resolution-dependence of the root-mean-square deviations (RMSDs) of bond lengths and angles from their restrained ideal values in macromolecular refinement, as well as their suggestions for the use of variable standard uncertainties dependent on atomic displacement parameters (ADPs) and occupancies. Whilst many of the comments and suggestions in the paper regarding updates for the ideal geometry values proposed by Engh and Huber are entirely reasonable and supported by the experimental evidence, the recommendations concerning the optimal values of RMSDs appear to be in conflict with previous experimental and theoretical work in this area [Tickle et al. (1998), Acta Cryst. D54, 243-252] and indeed appear to be based on a misunderstanding of the distinction between RMSD and standard uncertainty (SU). In contrast, it is proposed here that the optimal values of all desired weighting parameters, in particular the weighting parameters for the ADP differences and for the diffraction terms, be estimated by the purely objective procedure of maximizing the experiment-based log(free likelihood). In principle, this allows all weighting parameters that are not known accurately a priori to be scaled globally, relative to those that are known accurately, for an optimal refinement. The RMS Z score (RMSZ) is recommended as a more satisfactory statistic than the RMSD to assess the extent to which the geometry deviates from the ideal values and a theoretical rationale for the results obtained is presented in which the optimal RMSZ is identified as the calculated versus true Z-score correlation coefficient, the latter being a monotonic function of the resolution cutoff of the data. Regarding the proposal to use variable standard uncertainties, it is suggested that any departure from the current

  4. The active site of hen egg-white lysozyme: flexibility and chemical bonding

    SciTech Connect

    Held, Jeanette Smaalen, Sander van

    2014-04-01

    Chemical bonding at the active site of lysozyme is analyzed on the basis of a multipole model employing transferable multipole parameters from a database. Large B factors at low temperatures reflect frozen-in disorder, but therefore prevent a meaningful free refinement of multipole parameters. Chemical bonding at the active site of hen egg-white lysozyme (HEWL) is analyzed on the basis of Bader’s quantum theory of atoms in molecules [QTAIM; Bader (1994 ▶), Atoms in Molecules: A Quantum Theory. Oxford University Press] applied to electron-density maps derived from a multipole model. The observation is made that the atomic displacement parameters (ADPs) of HEWL at a temperature of 100 K are larger than ADPs in crystals of small biological molecules at 298 K. This feature shows that the ADPs in the cold crystals of HEWL reflect frozen-in disorder rather than thermal vibrations of the atoms. Directly generalizing the results of multipole studies on small-molecule crystals, the important consequence for electron-density analysis of protein crystals is that multipole parameters cannot be independently varied in a meaningful way in structure refinements. Instead, a multipole model for HEWL has been developed by refinement of atomic coordinates and ADPs against the X-ray diffraction data of Wang and coworkers [Wang et al. (2007), Acta Cryst. D63, 1254–1268], while multipole parameters were fixed to the values for transferable multipole parameters from the ELMAM2 database [Domagala et al. (2012), Acta Cryst. A68, 337–351] . Static and dynamic electron densities based on this multipole model are presented. Analysis of their topological properties according to the QTAIM shows that the covalent bonds possess similar properties to the covalent bonds of small molecules. Hydrogen bonds of intermediate strength are identified for the Glu35 and Asp52 residues, which are considered to be essential parts of the active site of HEWL. Furthermore, a series of weak C

  5. How precise are measurements of unit-cell dimensions from single crystals?

    PubMed

    Herbstein, F H

    2000-08-01

    The results of single-site and many-site measurements of cell dimensions from single crystals are compared for Bond and four-circle diffractometers using samples of corundum (essentially pure rhombohedral alpha-Al2O3, aluminum oxide) of high diffraction quality, where the effects of small changes in temperature and composition (Cr2O3, chromium oxide, in solid solution) can be taken into account. Similar comparisons are made for four-circle diffractometer measurements on ruby (alpha-Al2O3, with 0.46 wt % Cr in solid solution). The precisions are some parts in 10(5). There is partial support for the Taylor-Kennard [Acta Cryst. (1986), B42, 112-120] dictum that standard uncertainties (s.u.s) of cell parameters from routine four-circle diffractometer measurements are less than those for many-site measurements by factors of 5 for cell lengths and 2.5 for cell angles. For organic crystals, independent repetitions of adequate quality for comparison and analysis of routine four-circle diffractometer measurements are available only for alpha-oxalic acid dihydrate and anthracene. The experimental standard uncertainties given for these two crystals agree reasonably well with the sample s.u.s at room temperature, but appreciably less well at approximately 100 K, again giving partial support to the Taylor-Kennard dictum. The relation between specimen characteristics and attainable precision is emphasized; the precisions for routine measurements on good quality organic crystals are some parts in 10(4). Area-detector measurements of cell dimensions have also been appraised; currently published s.u.s from such measurements appear to be highly unreliable, and this is supported by a recent analysis of the operation of such diffractometers [Paciorek et al. (1999). Acta Cryst. A55, 543-557]. Formulation of a standard protocol for such measurements is badly needed. The dangers inherent in high degrees of replication are illustrated by recounting Kapteyn's Parable of the Chinese Emperor

  6. Advances in the EDM-DEDM procedure.

    PubMed

    Caliandro, Rocco; Carrozzini, Benedetta; Cascarano, Giovanni Luca; Giacovazzo, Carmelo; Mazzone, Anna Maria; Siliqi, Dritan

    2009-03-01

    The DEDM (difference electron-density modification) algorithm has been described in a recent paper [Caliandro et al. (2008), Acta Cryst. A64, 519-528]: it breaks down the collinearity between model structure phases and difference structure phase estimates. The new difference electron-density produced by DEDM, summed to the calculated Fourier maps, is expected to provide a representation of the full structure that is more accurate than that obtained by the observed Fourier synthesis. In the same paper, the DEDM algorithm was combined with the EDM (electron-density modification) approach to give the EDM-DEDM procedure which, when applied to practical molecular-replacement cases, was able to improve the model structures. In this paper, it is shown that EDM-DEDM suffers from some critical points that did not allow cyclical application of the procedure. These points are identified and modifications are made to allow iteration of the procedure. The applications indicate that EDM-DEDM may become a fundamental tool in protein crystallography.

  7. Improving experimental phases for strong reflections prior to density modification

    SciTech Connect

    Uervirojnangkoorn, Monarin; Hilgenfeld, Rolf; Terwilliger, Thomas C.; Read, Randy J.

    2013-09-20

    Experimental phasing of diffraction data from macromolecular crystals involves deriving phase probability distributions. These distributions are often bimodal, making their weighted average, the centroid phase, improbable, so that electron-density maps computed using centroid phases are often non-interpretable. Density modification brings in information about the characteristics of electron density in protein crystals. In successful cases, this allows a choice between the modes in the phase probability distributions, and the maps can cross the borderline between non-interpretable and interpretable. Based on the suggestions by Vekhter [Vekhter (2005), Acta Cryst. D61, 899–902], the impact of identifying optimized phases for a small number of strong reflections prior to the density-modification process was investigated while using the centroid phase as a starting point for the remaining reflections. A genetic algorithm was developed that optimizes the quality of such phases using the skewness of the density map as a target function. Phases optimized in this way are then used in density modification. In most of the tests, the resulting maps were of higher quality than maps generated from the original centroid phases. In one of the test cases, the new method sufficiently improved a marginal set of experimental SAD phases to enable successful map interpretation. Lastly, a computer program,SISA, has been developed to apply this method for phase improvement in macromolecular crystallography.

  8. Improving experimental phases for strong reflections prior to density modification

    DOE PAGES

    Uervirojnangkoorn, Monarin; Hilgenfeld, Rolf; Terwilliger, Thomas C.; Read, Randy J.

    2013-09-20

    Experimental phasing of diffraction data from macromolecular crystals involves deriving phase probability distributions. These distributions are often bimodal, making their weighted average, the centroid phase, improbable, so that electron-density maps computed using centroid phases are often non-interpretable. Density modification brings in information about the characteristics of electron density in protein crystals. In successful cases, this allows a choice between the modes in the phase probability distributions, and the maps can cross the borderline between non-interpretable and interpretable. Based on the suggestions by Vekhter [Vekhter (2005), Acta Cryst. D61, 899–902], the impact of identifying optimized phases for a small number ofmore » strong reflections prior to the density-modification process was investigated while using the centroid phase as a starting point for the remaining reflections. A genetic algorithm was developed that optimizes the quality of such phases using the skewness of the density map as a target function. Phases optimized in this way are then used in density modification. In most of the tests, the resulting maps were of higher quality than maps generated from the original centroid phases. In one of the test cases, the new method sufficiently improved a marginal set of experimental SAD phases to enable successful map interpretation. Lastly, a computer program,SISA, has been developed to apply this method for phase improvement in macromolecular crystallography.« less

  9. Crystal structure of penta­kis­(ethyl­enedi­amine-κ2 N,N′)lanthanum(III) trichloride–ethylene­diamine–dichloromethane (1/1/1)

    PubMed Central

    Sartain, Hope T.; Staples, Richard J.; Biros, Shannon M.

    2014-01-01

    We report here the crystal structure of a ten-coordinate lanthanum(III) metal coordinated by five bidentate ethyl­enedi­amine ligands, [La(C2H8N2)5]Cl3·C2H8N2·CH2Cl2. One free ethyl­enedi­amine mol­ecule and three Cl− anions are also located in the asymmetric unit. The overall structure is held together by an extensive hydrogen-bonding network between the Cl− anions and the NH groups on the metal-bound ethyl­enedi­amine ligands. The free ethyl­enedi­amine mol­ecule is held in an ordered position by additional hydrogen bonds involving both the chlorides and –NH groups on the metal-bound ligands. One highly disordered mol­ecule of di­chloro­methane is located on an inversion center; however, all attempts to model this disorder were unsuccessful. The electron density in this space was removed using the BYPASS procedure [van der Sluis & Spek (1990 ▶). Acta Cryst. A46, 194–201]. PMID:25484764

  10. Azole. 44. Uber morpholinonitroimidazolderivate

    PubMed

    Gzella; Wrzeciono; Poppel

    2000-09-01

    The structure analyses of racemic 3-chloro-1-(4-morpholino-5-nitroimidazol-1-yl)propan-2-ol, C(10)H(15)ClN(4)O(4), (II), and 3-chloro-1-(5-morpholino-4-nitroimidazol-1-yl)propan-2-ol, C(10)H(15)ClN(4)O(4), (III), have been undertaken in order to determine the position of the morpholine residue in these two isomers. The morpholine residue in (II) is connected at the 4-position, while in (III), it is connected at the 5-position of the imidazole ring. The morpholine mean planes and nitro groups in the two compounds deviate from the imidazole planes to different extents. The nitro groups in (II) and (III) take part in the conjugation system of the imidazole rings. In consequence, the exocyclic C-N bonds are significantly shorter than the normal single Csp(2)-NO(2) bond and the nitro groups in (II) and (III) show an extraordinary stability on treatment with morpholine and piperidine [Gzella, Wrzeciono & Poppel (1999). Acta Cryst. C55, 1562-1565]. In the crystal lattice, the molecules of both compounds are linked by O-H.N and C-H.O intermolecular hydrogen bonds. PMID:10986519

  11. Theoretical study of the properties of X-ray diffraction moiré fringes. I.

    PubMed

    Yoshimura, Jun-ichi

    2015-07-01

    A detailed and comprehensive theoretical description of X-ray diffraction moiré fringes for a bicrystal specimen is given on the basis of a calculation by plane-wave dynamical diffraction theory. Firstly, prior to discussing the main subject of the paper, a previous article [Yoshimura (1997). Acta Cryst. A53, 810-812] on the two-dimensionality of diffraction moiré patterns is restated on a thorough calculation of the moiré interference phase. Then, the properties of moiré fringes derived from the above theory are explained for the case of a plane-wave diffraction image, where the significant effect of Pendellösung intensity oscillation on the moiré pattern when the crystal is strained is described in detail with theoretically simulated moiré images. Although such plane-wave moiré images are not widely observed in a nearly pure form, knowledge of their properties is essential for the understanding of diffraction moiré fringes in general. PMID:25970298

  12. On the group-theoretical approach to the study of interpenetrating nets.

    PubMed

    Baburin, Igor A

    2016-05-01

    Using group-subgroup and group-supergroup relations, a general theoretical framework is developed to describe and derive interpenetrating 3-periodic nets. The generation of interpenetration patterns is readily accomplished by replicating a single net with a supergroup G of its space group H under the condition that site symmetries of vertices and edges are the same in both H and G. It is shown that interpenetrating nets cannot be mapped onto each other by mirror reflections because otherwise edge crossings would necessarily occur in the embedding. For the same reason any other rotation or roto-inversion axes from G \\ H are not allowed to intersect vertices or edges of the nets. This property significantly narrows the set of supergroups to be included in the derivation of interpenetrating nets. A procedure is described based on the automorphism group of a Hopf ring net [Alexandrov et al. (2012). Acta Cryst. A68, 484-493] to determine maximal symmetries compatible with interpenetration patterns. The proposed approach is illustrated by examples of twofold interpenetrated utp, dia and pcu nets, as well as multiple copies of enantiomorphic quartz (qtz) networks. Some applications to polycatenated 2-periodic layers are also discussed. PMID:27126113

  13. Competition of Bergman-type approximants with other packing motifs in the Cu-Zr system

    NASA Astrophysics Data System (ADS)

    Zhang, Feng; Jin, Min; Wang, X. W.; Wang, Cai-Zhuang; Kramer, M. J.; Mendelev, M. I.; Ho, Kai-Ming

    2012-02-01

    Knowledge about the topological and chemical ordering in metallic liquids and glasses is essential in predicting phase selection and understanding glass formation dynamics. Taking the Cu-Zr system as an example, previous studies have established Bergman-type medium-range ordering (MRO) from a structural analysis with cluster alignment methods [1]. In this study, we examine the thermodynamic stability of a crystalline approximant of Bergman-type quasicrystals [2] against packing geometries existing in other intermetallic compounds for a wide range of Cu compositions. The most stable structures for each structural motif at each Cu composition are obtained using an efficient genetic-algorithm search. Our results show that the Bergman-type approximant structure is thermodynamically favored over other packing geometries at the glass-forming region with Cu compositions around 65%, reaffirming the Bergman-type MRO is the lowest energy in Cu-Zr glasses.[4pt] [1] X. W. Fang, C. Z. Wang, Y. X. Yao, Z. J. Ding, and K. M. Ho, Phys. Rev. B 82, 184204 (2010).[0pt] [2] G. Bergman J. L. T. Waugh, and L. Pauling, Acta Cryst. 10, 254 (1957).

  14. Crystal structure of Sc1.91In1.39Mo15Se19, containing Mo6 and Mo9 clusters.

    PubMed

    Gougeon, Patrick; Gall, Philippe; Salloum, Diala

    2015-07-01

    The structure of scandium indium penta-deca-molybdenum nona-deca-selenide, Sc1.91In1.39Mo15Se19, is isotypic with In2.9Mo15Se19 [Grüttner et al. (1979 ▸). Acta Cryst. B35, 285-292]. It is characterized by two cluster units Mo6Se (i) 8Se (a) 6 and Mo9Se (i) 11Se (a) 6 (where i represents inner and a apical atoms) that are present in a 1:1 ratio. The cluster units are centered at Wyckoff positions 2b and 2c and have point-group symmetry -3 and -6, respectively. The clusters are inter-connected through additional Mo-Se bonds. Sc-Se and In-Se bonds complete the structural set-up. In the title compound, the Sc(3+) cations replace the trivalent indium atoms present in In2.9Mo15Se19, and a deficiency is observed at the monovalent indium site. One Mo, one Se and the Sc atom are situated on mirror planes, whereas two other Se atoms and the In atom are situated on threefold rotation axes. PMID:26279861

  15. Crystal structure of cis-bis-{4-phenyl-1-[(3R)-1,7,7-tri-methyl-2-oxobi-cyclo-[2.2.1]heptan-3-ylidene]thio-semicarbazidato-κ(3) O,N (1),S}cadmium(II) with an unknown solvent mol-ecule.

    PubMed

    Nogueira, Vanessa Senna; Bresolin, Leandro; Näther, Christian; Jess, Inke; de Oliveira, Adriano Bof

    2015-12-01

    The reaction between the racemic mixture of the camphor-4-phenyl-thio-semicarbazone derivative and cadmium acetate dihydrate yielded the title compound, [Cd(C17H20N3OS)2]. The Cd(II) ion is six-coordinated in a distorted octa-hedral environment by two deprotonated thio-semicarbazone ligands acting as an O,N,S-donor in a tridentate chelating mode, forming five-membered chelate rings. In the crystal, the mol-ecules are connected via pairs of N-H⋯S and C-H⋯S inter-actions, building centrosymmetric dimers. One of the ligands is disordered in the campher unit over two sets of sites with site-occupancy factors of 0.7 and 0.3. The structure contains additional solvent mol-ecules, which are disordered and for which no reasonable split model was found. Therefore, the data were corrected for disordered solvent using the SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9-18] in PLATON. Since the disordered solvents were removed by data processing, and the number of solvent entities was a suggestion only, they were not considered in the chemical formula and subsequent chemical or crystal information. PMID:26870441

  16. Can I solve my structure by SAD phasing? Planning an experiment, scaling data and evaluating the useful anomalous correlation and anomalous signal.

    PubMed

    Terwilliger, Thomas C; Bunkóczi, Gábor; Hung, Li Wei; Zwart, Peter H; Smith, Janet L; Akey, David L; Adams, Paul D

    2016-03-01

    A key challenge in the SAD phasing method is solving a structure when the anomalous signal-to-noise ratio is low. Here, algorithms and tools for evaluating and optimizing the useful anomalous correlation and the anomalous signal in a SAD experiment are described. A simple theoretical framework [Terwilliger et al. (2016), Acta Cryst. D72, 346-358] is used to develop methods for planning a SAD experiment, scaling SAD data sets and estimating the useful anomalous correlation and anomalous signal in a SAD data set. The phenix.plan_sad_experiment tool uses a database of solved and unsolved SAD data sets and the expected characteristics of a SAD data set to estimate the probability that the anomalous substructure will be found in the SAD experiment and the expected map quality that would be obtained if the substructure were found. The phenix.scale_and_merge tool scales unmerged SAD data from one or more crystals using local scaling and optimizes the anomalous signal by identifying the systematic differences among data sets, and the phenix.anomalous_signal tool estimates the useful anomalous correlation and anomalous signal after collecting SAD data and estimates the probability that the data set can be solved and the likely figure of merit of phasing.

  17. A second monoclinic polymorph of {bis­[5-methyl-3-(trifluoro­meth­yl)pyrazol-1-yl]borato}{tris­[5-methyl-3-(trifluoro­meth­yl)pyrazol-1-yl]borato}cobalt(II): a structure containing a B—H⋯Co agostic inter­action

    PubMed Central

    Stibrany, Robert T.; Potenza, Joseph A.

    2011-01-01

    The title compound, [Co(C10H10BF6N4)(C15H13BF9N6)], is a polymorph of the previously reported neutral cobalt(II) complex [Stibrany & Potenza (2010 ▶). Acta Cryst. E66, m506–m507], which contains one each of the monoanionic ligands, bis­[5-methyl-3-(trifluoro­meth­yl)pyrazol-1-yl]borate (Bp) and tris­[5-methyl-3-(trifluoro­meth­yl)pyrazol-1-yl]borate (Tp). A distorted octahedral coordination geometry of the CoII atom results from ligation of an H atom, which is part of an agostic B—H⋯Co inter­action [H⋯Co = 2.12 (3) Å], and by five imine N atoms, two from a Bp ligand and three from a Tp ligand. Weak intra- and inter­molecular C—F⋯π inter­actions with F⋯centroid distances ranging from 3.025 (4) to 3.605 (4) Å are observed. PMID:21836897

  18. Difference in the structures of alanine tri- and tetra-peptides with antiparallel β-sheet assessed by X-ray diffraction, solid-state NMR and chemical shift calculations by GIPAW.

    PubMed

    Asakura, Tetsuo; Yazawa, Koji; Horiguchi, Kumiko; Suzuki, Furitsu; Nishiyama, Yusuke; Nishimura, Katsuyuki; Kaji, Hironori

    2014-01-01

    Alanine oligomers provide a key structure for silk fibers from spider and wild silkworms.We report on structural analysis of L-alanyl-L-alanyl-L-alanyl-L-alanine (Ala)4 with anti-parallel (AP) β-structures using X-ray and solid-state NMR. All of the Ala residues in the (Ala)4 are in equivalent positions, whereas for alanine trimer (Ala)3 there are two alternative locations in a unit cell as reported previously (Fawcett and Camerman, Acta Cryst., 1975, 31, 658-665). (Ala)4 with AP β-structure is more stable than AP-(Ala)3 due to formation of the stronger hydrogen bonds. The intermolecular structure of (Ala)4 is also different from polyalanine fiber structure, indicating that the interchain arrangement of AP β-structure changes with increasing alanine sequencelength. Furthermore the precise (1)H positions, which are usually inaccesible by X-ray diffraction method, are determined by high resolution (1)H solid state NMR combined with the chemical shift calculations by the gauge-including projector augmented wave method.

  19. Ring-strain release in neutral and dicationic 7,8,17,18-tetra-bromo-5,10,15,20-tetra-phenyl-porphyrin: crystal structures of C44H26Br4N4 and C44H28Br4N4 (2+)·2ClO4 (-)·3CH2Cl2.

    PubMed

    Scheidt, W Robert; Duval, Hugues F; Oliver, Allen G

    2016-06-01

    Two porphyrin complexes were studied to determine the effects of protonation on ring deformation within the porphyrin. The porphyrin 7,8,17,18-tetra-bromo-5,10,15,20-tetra-phenyl-porphyrin, C44H26Br4N4, was selected because the neutral species is readily doubly protonated to yield a dication, which was crystallized here with perchlorate counter-ions as a di-chloro-methane tris-olvate, C44H28Br4N4 (2+)·2ClO4 (-)·3CH2Cl2. The centrosymmetric neutral species is observed to have a mild 'ruffling' of the pyrrole rings and is essentially planar throughout; intra-molecular N-H⋯N hydrogen bonds occur. In contrast, the dication exhibits considerable deformation, with the pyrrole rings oriented well out of the plane of the porphyrin, resulting in a 'saddle' conformation of the ring. The charged species forms N-H⋯O hydrogen bonds to the perchlorate anions, which lie above and below the plane of the porphyrin ring. Distortions to the planarity of the pyrrole rings in both cases are very minor. The characterization of the neutral species represents a low-temperature redetermination of the previous room-temperature analyses [Zou et al. (1995 ▸). Acta Cryst. C51, 760-761; Rayati et al. (2008 ▸). Polyhedron, pp. 2285-2290], which showed disorder and physically unrealistic displacement parameters. PMID:27308051

  20. Bis[2-(hy-droxy-imino-meth-yl)phenolato]nickel(II): a second monoclinic polymorph.

    PubMed

    Rusanova, Julia A; Buvaylo, Elena A; Rusanov, Eduard B

    2011-01-15

    The title compound, [Ni(C(7)H(6)NO(2))(2)], (I), is a second monoclinic polymorph of the compound, (II), reported by Srivastava et al. [Acta Cryst. (1967), 22, 922] and Mereiter [Private communication (2002) CCDC refcode NISALO01]. The bond lengths and angles are similar in both structures. The mol-ecule in both structures lies on a crystallographic inversion center and both have an inter-nal hydrogen bond. The title compound crystallizes in the space group P2(1)/c (Z = 2), whereas compound (II) is in the space group P2(1)/n (Z = 2) with a similar cell volume but different cell parameters. In both polymorphs, mol-ecules are arranged in the layers but in contrast to the previously published compound (II) where the dihedral angle between the layers is 86.3°, in the title polymorph the same dihedral angle is 29.4°. The structure of (I) is stabilized by strong intra-molecular O-H⋯O hydrogen bonding between the O-H group and the phenolate O atom.

  1. Crystal structure of a new monoclinic polymorph of N-(4-methyl­phen­yl)-3-nitro­pyridin-2-amine

    PubMed Central

    Aznan, Aina Mardia Akhmad; Abdullah, Zanariah; Lee, Vannajan Sanghiran; Tiekink, Edward R. T.

    2014-01-01

    The title compound, C12H11N3O2, is a second monoclinic polymorph (P21, with Z′ = 4) of the previously reported monoclinic (P21/c, with Z′ = 2) form [Akhmad Aznan et al. (2010 ▶). Acta Cryst. E66, o2400]. Four independent mol­ecules comprise the asymmetric unit, which have the common features of a syn disposition of the pyridine N atom and the toluene ring, and an intra­molecular amine–nitro N—H⋯O hydrogen bond. The differences between mol­ecules relate to the dihedral angles between the rings which range from 2.92 (19) to 26.24 (19)°. The geometry-optimized structure [B3LYP level of theory and 6–311 g+(d,p) basis set] has the same features except that the entire mol­ecule is planar. In the crystal, the three-dimensional architecture is consolidated by a combination of C—H⋯O, C—H⋯π, nitro-N—O⋯π and π–π inter­actions [inter-centroid distances = 3.649 (2)–3.916 (2) Å]. PMID:25249854

  2. A new polymorph of physcion.

    PubMed

    Hopf, Henning; Jones, Peter G; Goclik, Eva; Aust, Pauline; Rödiger, Johanna

    2012-08-01

    The structure of the title compound, 7-methoxy-2-methyl-4,5-dihydroxyanthracene-9,10-dione, C(16)H(12)O(5), was originally reported by Ulický et al. [Acta Cryst. (1991). C47, 1879-1881] in the space group P2(1)2(1)2(1) [polymorph (Io)]. The new polymorph, (Im), crystallizes in the space group P2(1)/c. The molecular structures are closely similar, with both -OH groups forming intramolecular hydrogen bonds to one of the neighbouring quinone O atoms, thus slightly lengthening this C=O bond; the pattern of C-C bond lengths in the ring system is consistent with some contribution from a resonance form with a negative charge at the hydrogen-bonded quinone O atom and an aromatic region around its neighbouring C atoms. The packing of (Im) is simpler than the extensively crosslinked pattern of (Io), with molecular tapes connected by classical (but three-centre) and `weak' hydrogen bonds, parallel to [201].

  3. A log-likelihood-gain intensity target for crystallographic phasing that accounts for experimental error.

    PubMed

    Read, Randy J; McCoy, Airlie J

    2016-03-01

    The crystallographic diffraction experiment measures Bragg intensities; crystallographic electron-density maps and other crystallographic calculations in phasing require structure-factor amplitudes. If data were measured with no errors, the structure-factor amplitudes would be trivially proportional to the square roots of the intensities. When the experimental errors are large, and especially when random errors yield negative net intensities, the conversion of intensities and their error estimates into amplitudes and associated error estimates becomes nontrivial. Although this problem has been addressed intermittently in the history of crystallographic phasing, current approaches to accounting for experimental errors in macromolecular crystallography have numerous significant defects. These have been addressed with the formulation of LLGI, a log-likelihood-gain function in terms of the Bragg intensities and their associated experimental error estimates. LLGI has the correct asymptotic behaviour for data with large experimental error, appropriately downweighting these reflections without introducing bias. LLGI abrogates the need for the conversion of intensity data to amplitudes, which is usually performed with the French and Wilson method [French & Wilson (1978), Acta Cryst. A35, 517-525], wherever likelihood target functions are required. It has general applicability for a wide variety of algorithms in macromolecular crystallography, including scaling, characterizing anisotropy and translational noncrystallographic symmetry, detecting outliers, experimental phasing, molecular replacement and refinement. Because it is impossible to reliably recover the original intensity data from amplitudes, it is suggested that crystallographers should always deposit the intensity data in the Protein Data Bank. PMID:26960124

  4. Getting off the Bain path: Are there any metastable states of cubic elements?

    NASA Astrophysics Data System (ADS)

    Mehl, Michael J.; Boyer, Larry L.

    2003-03-01

    Body-centered and face-centered cubic crystals can be considered as special cases of a body-centered tetragonal crystal with c/a = 1 and 2, respectively. First-principles calculations along this Bain path show that elements with an fcc (bcc) ground state are elastically unstable with respect to a tetragonal distortion in the bcc (fcc) phase. Starting with a normally fcc element and calculating E(c/a) for c/a < 1 we find a local minimum near c/a = 2/3, while for a bcc element we find a local minimum at some c/a > 2. It is tempting to conclude that these bct minima, which are required by continuity, are metastable, but calculations by several authors show that, at least for Al, Cu, and Pd, the bct structures are unstable with respect to an orthorhombic distortion. We use a simple "magic strain" construction(L. L. Boyer, Acta Cryst. A) 45, FC29 (1989).(M. J. Mehl and L. L. Boyer, Phys. Rev. B) 43, 9498 (1991). to study the stability of these bct states, and present examples which suggest that no fcc or bcc element has a metastable bct state.

  5. Inversion twinning in a second polymorph of the hydrochloride salt of the recreational drug ethylone.

    PubMed

    Cameron, T Stanley; Grossert, J Stuart; Maheux, Chad R; Alarcon, Idralyn Q; Copeland, Catherine R; Linden, Anthony

    2015-04-01

    A second polymorph of the hydrochloride salt of the recreational drug ethylone, C12H16NO3(+)·Cl(-), is reported [systematic name: (±)-2-ethylammonio-1-(3,4-methylenedioxyphenyl)propane-1-one chloride]. This polymorph, denoted form (A), appears in crystallizations performed above 308 K. The originally reported form (B) [Wood et al. (2015). Acta Cryst. C71, 32-38] crystallizes preferentially at room temperature. The conformations of the cations in the two forms differ by a 180° rotation about the C-C bond linking the side chain to the aromatic ring. Hydrogen bonding links the cations and anions in both forms into similar extended chains in which any one chain contains only a single enantiomer of the chiral cation, but the packing of the ions is different. In form (A), the aromatic rings of adjacent chains interleave, but pack equally well if neighbouring chains contain the same or opposite enantiomorph of the cation. The consequence of this is then near perfect inversion twinning in the structure. In form (B), neighbouring chains are always inverted, leading to a centrosymmetric space group. The question as to why the polymorphs crystallize at slightly different temperatures has been examined by density functional theory (DFT) and lattice energy calculations and a consideration of packing compactness. The free energy (ΔG) of the crystal lattice for polymorph (A) lies some 52 kJ mol(-1) above that of polymorph (B). PMID:25836283

  6. Can I solve my structure by SAD phasing? Planning an experiment, scaling data and evaluating the useful anomalous correlation and anomalous signal

    PubMed Central

    Terwilliger, Thomas C.; Bunkóczi, Gábor; Hung, Li-Wei; Zwart, Peter H.; Smith, Janet L.; Akey, David L.; Adams, Paul D.

    2016-01-01

    A key challenge in the SAD phasing method is solving a structure when the anomalous signal-to-noise ratio is low. Here, algorithms and tools for evaluating and optimizing the useful anomalous correlation and the anomalous signal in a SAD experiment are described. A simple theoretical framework [Terwilliger et al. (2016 ▸), Acta Cryst. D72, 346–358] is used to develop methods for planning a SAD experiment, scaling SAD data sets and estimating the useful anomalous correlation and anomalous signal in a SAD data set. The phenix.plan_sad_experiment tool uses a database of solved and unsolved SAD data sets and the expected characteristics of a SAD data set to estimate the probability that the anomalous substructure will be found in the SAD experiment and the expected map quality that would be obtained if the substructure were found. The phenix.scale_and_merge tool scales unmerged SAD data from one or more crystals using local scaling and optimizes the anomalous signal by identifying the systematic differences among data sets, and the phenix.anomalous_signal tool estimates the useful anomalous correlation and anomalous signal after collecting SAD data and estimates the probability that the data set can be solved and the likely figure of merit of phasing. PMID:26960123

  7. Crystal structure of 2-[(3S,4S)-4-(anthracen-9-yl)-1-(4-meth­oxy­phen­yl)-2-oxoazetidin-3-yl]-2-aza-2H-phenalene-1,3-dione unknown solvate

    PubMed Central

    Çelik, Ísmail; Akkurt, Mehmet; Jarrahpour, Aliasghar; Rad, Javad Ameri; Çelik, Ömer

    2015-01-01

    The central β-lactam ring of the title compound, C36H24N2O4, is almost planar (r.m.s. deviation = 0.003 Å) and makes dihedral angles of 17.17 (19), 89.76 (17) and 78.44 (17)° with the benzene ring, the anthracene ring (r.m.s. deviation = 0.003 Å) and the 1H-benzo[de]iso­quinoline-1,3(2H)-dione moiety, which is nearly planar [maximum deviation = 0.098 (2) Å], respectively. The mol­ecular structure is stabilized by an intra­molecular C—H⋯N hydrogen bond. In the crystal, mol­ecules are linked via C—H⋯π and π–π stacking inter­actions [centroid–centroid distances = 3.5270 (19) and 3.779 (2) Å], forming a three-dimensional structure. A region of disordered electron density, probably disordered solvent mol­ecules, was treated with the SQUEEZE procedure in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9–18], which indicated a solvent cavity of 322 Å3 containing approximately 91 electrons. Their formula mass and unit-cell characteristics were not taken into account during the refinement. PMID:25844239

  8. 3-Amino-1-(3,4-dimeth-oxy-phen-yl)-9,10-dihydro-phenanthrene-2,4-dicarbonitrile.

    PubMed

    Asiri, Abdullah M; Faidallah, Hassan M; Alamry, Khalid A; Ng, Seik Weng; Tiekink, Edward R T

    2012-04-01

    In the title compound, C(24)H(19)N(3)O(2), the partially saturated ring adopts a distorted half-chair conformation with the methyl-ene-C atom closest to the amino-benzene ring lying 0.664 (3) Å out of the plane defined by the five remaining atoms (r.m.s. deviation = 0.1429 Å. The dihedral angle [32.01 (10)°] between the benzene rings on either side of this ring indicates a significant fold in this part of the mol-ecule. The dimeth-oxy-substituted benzene ring is almost orthogonal to the benzene ring to which it is attached [dihedral angle = 72.03 (9)°]. The mol-ecule has been observed previously as the major component of a 1:19 co-crystal with 2-amino-4-(3,4-dimeth-oxy-phen-yl)-5,6-dihydro-benzo[ha]quinoline-3-carbonitrile [Asiri et al. (2011). Acta Cryst. E67, o2873-o2873]. Supra-molecular chains with base vector [201] are formed in the crystal structure via N-H⋯O hydrogen bonds between the amino H atoms of one mol-ecule inter-acting with the meth-oxy O atoms of a neighbouring mol-ecule. The chains are linked into a three-dimensional architecture by C-H⋯π inter-actions. PMID:22589974

  9. Direct phasing in femtosecond nanocrystallography. I. Diffraction characteristics.

    PubMed

    Chen, Joe P J; Spence, John C H; Millane, Rick P

    2014-03-01

    X-ray free-electron lasers solve a number of difficulties in protein crystallography by providing intense but ultra-short pulses of X-rays, allowing collection of useful diffraction data from nanocrystals. Whereas the diffraction from large crystals corresponds only to samples of the Fourier amplitude of the molecular transform at the Bragg peaks, diffraction from very small crystals allows measurement of the diffraction amplitudes between the Bragg samples. Although highly attenuated, these additional samples offer the possibility of iterative phase retrieval without the use of ancillary experimental data [Spence et al. (2011). Opt. Express, 19, 2866-2873]. This first of a series of two papers examines in detail the characteristics of diffraction patterns from collections of nanocrystals, estimation of the molecular transform and the noise characteristics of the measurements. The second paper [Chen et al. (2014). Acta Cryst. A70, 154-161] examines iterative phase-retrieval methods for reconstructing molecular structures in the presence of the variable noise levels in such data.

  10. A log-likelihood-gain intensity target for crystallographic phasing that accounts for experimental error

    PubMed Central

    Read, Randy J.; McCoy, Airlie J.

    2016-01-01

    The crystallographic diffraction experiment measures Bragg intensities; crystallo­graphic electron-density maps and other crystallographic calculations in phasing require structure-factor amplitudes. If data were measured with no errors, the structure-factor amplitudes would be trivially proportional to the square roots of the intensities. When the experimental errors are large, and especially when random errors yield negative net intensities, the conversion of intensities and their error estimates into amplitudes and associated error estimates becomes nontrivial. Although this problem has been addressed intermittently in the history of crystallographic phasing, current approaches to accounting for experimental errors in macromolecular crystallography have numerous significant defects. These have been addressed with the formulation of LLGI, a log-likelihood-gain function in terms of the Bragg intensities and their associated experimental error estimates. LLGI has the correct asymptotic behaviour for data with large experimental error, appropriately downweighting these reflections without introducing bias. LLGI abrogates the need for the conversion of intensity data to amplitudes, which is usually performed with the French and Wilson method [French & Wilson (1978 ▸), Acta Cryst. A35, 517–525], wherever likelihood target functions are required. It has general applicability for a wide variety of algorithms in macromolecular crystallography, including scaling, characterizing anisotropy and translational noncrystallographic symmetry, detecting outliers, experimental phasing, molecular replacement and refinement. Because it is impossible to reliably recover the original intensity data from amplitudes, it is suggested that crystallographers should always deposit the intensity data in the Protein Data Bank. PMID:26960124

  11. Can I solve my structure by SAD phasing? Planning an experiment, scaling data and evaluating the useful anomalous correlation and anomalous signal

    DOE PAGES

    Terwilliger, Thomas C.; Bunkóczi, Gábor; Hung, Li-Wei; Zwart, Peter H.; Smith, Janet L.; Akey, David L.; Adams, Paul D.

    2016-03-01

    A key challenge in the SAD phasing method is solving a structure when the anomalous signal-to-noise ratio is low. Here, we describe algorithms and tools for evaluating and optimizing the useful anomalous correlation and the anomalous signal in a SAD experiment. A simple theoretical framework [Terwilliger et al.(2016),Acta Cryst.D72, 346–358] is used to develop methods for planning a SAD experiment, scaling SAD data sets and estimating the useful anomalous correlation and anomalous signal in a SAD data set. Thephenix.plan_sad_experimenttool uses a database of solved and unsolved SAD data sets and the expected characteristics of a SAD data set to estimatemore » the probability that the anomalous substructure will be found in the SAD experiment and the expected map quality that would be obtained if the substructure were found. Thephenix.scale_and_mergetool scales unmerged SAD data from one or more crystals using local scaling and optimizes the anomalous signal by identifying the systematic differences among data sets, and thephenix.anomalous_signaltool estimates the useful anomalous correlation and anomalous signal after collecting SAD data and estimates the probability that the data set can be solved and the likely figure of merit of phasing.« less

  12. Crystal structure of [(E)-({2-[3-(2-{(1E)-[(carbamo­thioyl­amino)­imino]­meth­yl}phen­oxy)prop­oxy]phen­yl}methyl­idene)amino]­thio­urea with an unknown solvate

    PubMed Central

    Mague, Joel T.; Mohamed, Shaaban K.; Akkurt, Mehmet; Younes, Sabry H. H.; Albayati, Mustafa R.

    2015-01-01

    The title mol­ecule, C19H22N6O2S2, has crystallographically imposed C 2 symmetry, with the central C atom lying on the rotation axis. The O—C—C—C torsion angle for the central chain is −59.22 (16)° and the dihedral angle between the planes of the benzene rings is 75.20 (7)°. In the crystal, N—H⋯O and N—H⋯S inter­actions link the mol­ecules, forming a three-dimensional network encompassing channels running parallel to the c axis, which account for about 20% of the unit-cell volume. The contribution to the scattering from the highly disordered solvent mol­ecules in these channels was removed with the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18] in PLATON. The stated crystal data for M r, μ etc. do not take these into account. PMID:26279946

  13. Compounds with a 'stuffed' anti-bixbyite-type structure, analysed in terms of the Zintl-Klemm and coordination-defect concepts.

    PubMed

    Vegas, Angel; Martin, Raymond L; Bevan, D J M

    2009-02-01

    The bixbyite structure (Mn(2)O(3)) (Ia3) is often described as a distorted face-centered cubic (f.c.c.) array of Mn atoms, with O atoms occupying 3/4 of the tetrahedral holes. The empty M(4) tetrahedra are centred at 16c. In anti-bixbyite structures (Mg(3)N(2)), cation vacancies are centred in empty N(4) tetrahedra. If 16 hypothetical atoms were located at this site they would form the structure of gamma-Si. This means that anti-bixbyite structures are ideally prepared to accommodate Si(Ge) atoms at these holes. Several compounds (Li(3)AlN(2) and Li(3)ScN(2)) fully satisfy this expectation. They are really anti-bixbyites 'stuffed' with Al(Sc). The presence of these atoms in 16c is illuminated in the light of the extended Zintl-Klemm concept (EZKC) [Vegas & García-Baonza (2007). Acta Cryst. B63, 339-345], from which a compound would be the result of 'multiple resonance' pseudo-structures, emerging from electron transfers between any species pair (like or unlike atoms, cations or anions). The coordination-defect (CD) concept [Bevan & Martin (2008). J. Solid State Chem. 181, 2250-2259] is also consistent with the EZKC description of the pseudo-structures. A more profound insight into crystal structures is gained if one is not restricted to the contemplation of classical anions and cations in their conventional oxidation states.

  14. Crystal structure of cis-bis­{4-phenyl-1-[(3R)-1,7,7-tri­methyl-2-oxobi­cyclo­[2.2.1]heptan-3-ylidene]thio­semicarbazidato-κ3 O,N 1,S}cadmium(II) with an unknown solvent mol­ecule

    PubMed Central

    Nogueira, Vanessa Senna; Bresolin, Leandro; Näther, Christian; Jess, Inke; de Oliveira, Adriano Bof

    2015-01-01

    The reaction between the racemic mixture of the camphor-4-phenyl­thio­semicarbazone derivative and cadmium acetate dihydrate yielded the title compound, [Cd(C17H20N3OS)2]. The CdII ion is six-coordinated in a distorted octa­hedral environment by two deprotonated thio­semicarbazone ligands acting as an O,N,S-donor in a tridentate chelating mode, forming five-membered chelate rings. In the crystal, the mol­ecules are connected via pairs of N—H⋯S and C—H⋯S inter­actions, building centrosymmetric dimers. One of the ligands is disordered in the campher unit over two sets of sites with site-occupancy factors of 0.7 and 0.3. The structure contains additional solvent mol­ecules, which are disordered and for which no reasonable split model was found. Therefore, the data were corrected for disordered solvent using the SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9–18] in PLATON. Since the disordered solvents were removed by data processing, and the number of solvent entities was a suggestion only, they were not considered in the chemical formula and subsequent chemical or crystal information. PMID:26870441

  15. Crystal structure of an unknown solvate of bis­(tetra-n-butyl­ammonium) [N,N′-(4-tri­fluoro­methyl-1,2-phenyl­ene)bis­(oxamato)-κ4 O,N,N′,O′]nickelate(II)

    PubMed Central

    Eya’ane Meva, François; Schaarschmidt, Dieter; Rüffer, Tobias

    2015-01-01

    In the title compound, [N(C4H9)4]2[Ni(C11H3F3N2O6)] or [N(n-Bu)4]2[Ni(topbo)] [n-Bu = n-butyl and topbo = 4-tri­fluoro­methyl-1,2-phenyl­enebis(oxamate)], the Ni2+ cation is coordinated by two deprotonated amido N atoms and two carboxyl­ate O atoms, setting up a slightly distorted square-planar coordination environment. The [Ni(topbo]2− anion lies on a twofold rotation axis. Due to an incompatibility with the point-group symmetry of the complete mol­ecule, orientational disorder of the CF3 group is observed. The tetra­hedral ammonium cations and the anion are linked by weak inter­molecular C—H⋯O and C—H⋯F hydrogen-bonding inter­actions into a three-dimensional network. A region of electron density was treated with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9–18] following unsuccessful attempts to model it as plausible solvent mol­ecule(s). The given chemical formula and other crystal data do not take into account the unknown solvent mol­ecule. PMID:26090126

  16. (1-Methyl-1H-imidazole-κN 3)(1-methyl-2-nitroso­benzene-κN)(5,10,15,20-tetra­phenyl­porphyrinato-κ4 N)iron(II) di­chloro­methane monosolvate

    PubMed Central

    Abucayon, Erwin G.; Awasabisah, Dennis; Powell, Douglas R.; Richter-Addo, George B.

    2014-01-01

    The solvated title compound, [Fe(C44H28N4)(C4H6N2)(C7H7NO)]·CH2Cl2, is a porphyrin complex containing an octahedrally coordinated FeII atom with 1-methylimidazole [Fe—N = 2.0651 (17) Å] and o-nitro­sotoluene ligands at the axial positions. The o-nitro­sotoluene ligand is N-bound to iron(II) [Fe—N = 1.8406 (18)Å and Fe—N—O = 122.54 (14)°]. The axial N—Fe—N linkage is almost linear, with a bond angle of 177.15 (7)°. One phenyl group of the porphyrin ligand is disordered over two orientations in a 0.710 (3):0.290 (3) ratio. The di­chloro­methane solvent mol­ecule was severely disordered and its contribution to the scattering was removed with the SQUEEZE routine [van der Sluis & Spek (1990 ▶). Acta Cryst. A46, 194–201]. PMID:24764819

  17. A monoclinic polymorph of [(Z)-N-(3-chloro-phen-yl)-O-methyl-thio-carbamato-κS](tri-phenyl-phosphane-κP)gold(I): crystal structure and Hirshfeld surface analysis.

    PubMed

    Yeo, Chien Ing; Tan, Sang Loon; Tiekink, Edward R T

    2016-08-01

    The title compound, [Au(C8H7ClNOS)(C18H15P)], is a monoclinic (P21/n, Z' = 1; form β) polymorph of the previously reported triclinic form (P-1, Z' = 1; form α) [Tadbuppa & Tiekink (2010 ▸). Acta Cryst. E66, m664]. The mol-ecular structures of both forms feature an almost linear gold(I) coordination geometry [P-Au-S = 175.62 (5)° in the title polymorph], being coordinated by thiol-ate S and phosphane P atoms, a Z conformation about the C=N bond and an intra-molecular Au⋯O contact. The major conformational difference relates to the relative orientations of the residues about the Au-S bond: the P-Au-S-C torsion angles are -8.4 (7) and 106.2 (7)° in forms α and β, respectively. The mol-ecular packing of form β features centrosymmetric aggregates sustained by aryl-C-H⋯O inter-actions, which are connected into a three-dimensional network by aryl-C-H⋯π contacts. The Hirshfeld analysis of forms α and β shows many similarities with the notable exception of the influence of C-H⋯O inter-actions in form β. PMID:27536384

  18. Redetermined structure of 4,4'-bi-pyridine-1,4-phenyl-enedi-acetic acid (1/1) co-crystal.

    PubMed

    Paul, Rima; Bora, Sanchay Jyoti

    2015-10-01

    The asymmetric unit of the title 1:1 co-crystal, C10H8N2·C10H10O4, consists of one half-mol-ecule each of 4,4'-bi-pyridine and 1,4-phenyl-enedi-acetic acid: the complete mol-ecules are generated by crystallographic inversion centres. The dihedral angle between the -CO2H group and the benzene ring in the diacid is 73.02 (7)°. In the crystal, the components are linked by O-H⋯N hydrogen bonds, generating [1-2-1] chains of alternating amine and carb-oxy-lic acid mol-ecules. The chains are cross-linked by C-H⋯O inter-actions. This structure was previously incorrectly described as a (C10H10N2)(2+)·(C10H8O4)(2-) mol-ecular salt [Jia et al. (2009 ▸). Acta Cryst. E65, o2490-o2490]. PMID:26594486

  19. Protein energy landscapes determined by five-dimensional crystallography.

    PubMed

    Schmidt, Marius; Srajer, Vukica; Henning, Robert; Ihee, Hyotcherl; Purwar, Namrta; Tenboer, Jason; Tripathi, Shailesh

    2013-12-01

    Free-energy landscapes decisively determine the progress of enzymatically catalyzed reactions [Cornish-Bowden (2012), Fundamentals of Enzyme Kinetics, 4th ed.]. Time-resolved macromolecular crystallography unifies transient-state kinetics with structure determination [Moffat (2001), Chem. Rev. 101, 1569-1581; Schmidt et al. (2005), Methods Mol. Biol. 305, 115-154; Schmidt (2008), Ultrashort Laser Pulses in Medicine and Biology] because both can be determined from the same set of X-ray data. Here, it is demonstrated how barriers of activation can be determined solely from five-dimensional crystallography, where in addition to space and time, temperature is a variable as well [Schmidt et al. (2010), Acta Cryst. A66, 198-206]. Directly linking molecular structures with barriers of activation between them allows insight into the structural nature of the barrier to be gained. Comprehensive time series of crystallographic data at 14 different temperature settings were analyzed and the entropy and enthalpy contributions to the barriers of activation were determined. One hundred years after the discovery of X-ray scattering, these results advance X-ray structure determination to a new frontier: the determination of energy landscapes.

  20. 2-[(1,3-Benzo­thia­zol-2-yl)imino­meth­yl]-6-meth­oxy­phenol: a new monoclinic polymorph

    PubMed Central

    Affan, Md. Abu; Jessop, Philip G.; Salam, Md. Abdus; Halim, Siti Nadiah Binti Abdul; Tiekink, Edward R. T.

    2013-01-01

    The title compound, C15H12N2O2S, is a P21/c polymorph of a previously reported P21/n polymorph [Büyükgüngör et al. (2004 ▶). Acta Cryst. E60, o1414–o1416]. The dihedral angle between the benzo­thia­zole (r.m.s. deviation = 0.010 Å) and the benzene ring of 7.86 (6)° compares with 10.76 (10)° in the literature structure. The meth­oxy substituent is almost coplanar with the benzene ring to which it is attached [C—O—C—C torsion angle = 178.31 (14)°] and the conformation about the imine bond [1.287 (2) Å] is E. There is an intra­molecular O—H⋯N hydrogen bond and the hy­droxy O and thio­ether S atoms are syn. In the crystal, columns are formed along the b axis as centrosymmetric dimeric aggregates, mediated by C—H⋯O inter­actions and linked by π–π inter­actions between the thia­zole and benzene rings [centroid-to-centroid distance = 3.8256 (10) Å]. PMID:24109355

  1. Succinate esters: odd-even effects in melting points.

    PubMed

    Joseph, Sumy; Sathishkumar, Ranganathan

    2014-10-01

    Dialkyl succinates show a pattern of alternating behavior in their melting points, as the number of C atoms in the alkane side chain increases, unlike in the dialkyl oxalates [Joseph et al. (2011). Acta Cryst. B67, 525-534]. Dialkyl succinates with odd numbers of C atoms in the alkyl side chain show higher melting points than the immediately adjacent analogues with even numbers. The crystal structures and their molecular packing have been analyzed for a series of dialkyl succinates with 1-4 C atoms in the alkyl side chain. The energy difference (ΔE) between the optimized and observed molecular conformations, density, Kitaigorodskii packing index (KPI) and C-H...O interactions are considered to rationalize this behavior. In contrast to the dialkyl oxalates where a larger number of moderately strong C-H...O interactions were characteristic of oxalates with elevated melting points, here the molecular packing and the density play a major role in raising the melting point. On moving from oxalate to succinate esters the introduction of the C2 spacer adds two activated H atoms to the asymmetric unit, resulting in the formation of stronger C-H...O hydrogen bonds in all succinates. As a result the crystallinity of long-chain alkyl substituted esters improves enormously in the presence of hydrogen bonds from activated donors.

  2. A P212121 polymorph of (+)-clusianone

    PubMed Central

    Vaneesa Nagalingam, Sree; Wong Pik Ching, Janet; Khaled bin Break, Mohammed; Tahir, M. Ibrahim M.; Khoo, Teng-Jin

    2013-01-01

    The title compound, C33H42O4 [systematic name: (1S,5S,7R)-3-benzoyl-4-hy­droxy-8,8-dimethyl-1,5,7-tris­(3-methyl­but-2-­enyl)bi­cyclo­[3.3.1]nona-3-ene-2,9-dione], has a central bi­cyclo­[3.3.1]nonane-2,4,9-trione surrounded by tetra­prenyl­ated and benzoyl groups. The compound was recrystallized several times in methanol using both a slow evaporation method and with a crystal-seeding technique. This subsequently produced diffraction-quality crystals which crystallize in the ortho­rhom­bic space group P212121, in contrast to a previous report of a structure determination in the Pna21 space group [McCandlish et al. (1976 ▶). Acta Cryst. B32, 1793–1801]. The title compound has a melting point of 365–366 K, and a specific rotation [α]20 value of +51.94°. A strong intra­molecular O—H⋯O hydrogen bond is noted. In the crystal, mol­ecules are assembled in the ab plane by weak C—H⋯O inter­actions. PMID:24860292

  3. Crystal structure of an unknown tetra-hydro-furan solvate of tetra-kis-(μ 3-cyanato-κ(3) N:N:N)tetra-kis-[(triphenyl-phosphane-κP)-silver(I)].

    PubMed

    Frenzel, Peter; Schaarschmidt, Dieter; Jakob, Alexander; Lang, Heinrich

    2015-10-01

    In the title compound, [{[(C6H5)3P]Ag}4{NCO}4], a distorted Ag4N4-heterocubane core is set up by four Ag(I) ions being coordinated by the N atoms of the cyanato anions in a μ 3-bridging mode. In addition, a tri-phenyl-phosphine ligand is datively bonded to each of the Ag(I) ions. Intra-molecular Ag⋯Ag distances as short as 3.133 (9) Å suggest the presence of argentophilic (d (10)⋯d (10)) inter-actions. Five moderate-to-weak C-H⋯O hydrogen-bonding inter-actions are observed in the crystal structure, spanning a three-dimensional network. A region of electron density was treated with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9-18] following unsuccessful attempts to model it as being part of disordered tetra-hydro-furan solvent mol-ecules. The given chemical formula and other crystal data do not take into account these solvent mol-ecules.

  4. Crystal structure of tri-aqua-(2,6-di-methyl-pyrazine-κN (4))bis-(thio-cyanato-κN)manganese(II) 2,5-di-methyl-pyrazine disolvate.

    PubMed

    Suckert, Stefan; Wöhlert, Susanne; Jess, Inke; Näther, Christian

    2015-12-01

    In the crystal structure of the title complex, [Mn(NCS)2(C6H8N2)(H2O)3]·2C6H8N2, the Mn(II) cation is coordinated by two terminally N-bonded thio-cyanate anions, three water mol-ecules and one 2,6-di-methyl-pyrazine ligand within a slightly distorted N3O3 octa-hedral geometry; the entire complex mol-ecule is generated by the application of a twofold rotation axis. The asymmetric unit also contains an uncoordinating 2,5-di-methyl-pyrazine ligand in a general position. Obviously, the coordination to the 2,6-di-methyl-pyrazine ligand is preferred because coordination to the 2,5-di-methyl-pyrazine is hindered due to the bulky methyl group proximate to the N atom. The discrete complexes are linked by water-O-H⋯N(2,6-di-methyl-pyzazine/2,5-di-methyl-pyza-zine) hydrogen bonding, forming a three-dimensional network. In the crystal, mol-ecules are arranged in a way that cavities are formed in which unspecified, disordered solvent molecules reside. These were modelled employing the SQUEEZE routine in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The composition of the unit cell does not take into account the presence of the unspecified solvent.

  5. Crystal structure of 2-methyl-amino-4-(6-methyl-4-oxo-4H-chromen-3-yl)-3-nitro-pyrano[3,2-c]chromen-5(4H)-one with an unknown solvate.

    PubMed

    Raja, Rajamani; Kandhasamy, Subramani; Perumal, Paramasivam T; SubbiahPandi, A

    2015-09-01

    In the title compound, C23H16N2O7, the mean planes of the two chromene units (r.m.s. deviations = 0.031 and 0.064 Å) are almost normal to one another with a dihedral angle of 85.59 (6)°. The central six-membered pyran ring has a distorted envelope conformation, with the methine C atom at the flap. There is an intra-molecular N-H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, mol-ecules are linked by pairs of N-H⋯O hydrogen bonds, forming inversion dimers with an R 2 (2)(12) ring motif. The dimers are linked by pairs of C-H⋯O hydrogen bonds, enclosing R 2 (2)(6) ring motifs, forming zigzag chains along [001]. The chains are linked by a second pair of C-H⋯O hydrogen bonds, forming slabs parallel to (110). Within the slabs there are C-H⋯π inter-actions present. A region of disordered electron density was treated with the SQUEEZE procedure in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18] following unsuccessful attempts to model it as plausible solvent mol-ecule(s). The given chemical formula and other crystal data do not take into account the unknown solvent mol-ecule(s).

  6. Crystal structure of ethyl 3-amino-6-methyl-2-[(4-methyl-phen-yl)carbamo-yl]-4-[(E)-2-phenyl-ethen-yl]thieno[2,3-b]pyridine-5-carboxyl-ate monohydrate.

    PubMed

    Mague, Joel T; Akkurt, Mehmet; Mohamed, Shaaban K; Bakhite, Etify A; Albayati, Mustafa R

    2016-03-01

    In the title mol-ecule, C27H25N3O3S·H2O, the dihedral angle between the planes of the thienyl ring and the pendant p-tolyl group is 39.25 (6)°, while that between the pyridine ring and the pendant phenyl ring is 44.37 (6)°. In addition, there is a slight twist in the bicyclic core, with a dihedral angle of 2.39 (4)° between the thienyl and pyridine rings. The conformation of the carbamoyl moiety is partially determined by an intra-molecular N-H⋯O hydrogen bond. In the crystal, complementary N-H⋯O hydrogen bonds form dimers which are then associated into chains parallel to the c axis through O-H⋯N hydrogen bonds involving the water mol-ecule of crystallization. Electron density associated with an additional solvent mol-ecule of partial occupancy and disordered about a twofold axis was removed with the SQUEEZE procedure in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The given chemical formula and other crystal data do not take into account the unknown solvent molecule(s).

  7. Crystal structure of cis-bis-{4-phenyl-1-[(3R)-1,7,7-tri-methyl-2-oxobi-cyclo-[2.2.1]heptan-3-ylidene]thio-semicarbazidato-κ(3) O,N (1),S}cadmium(II) with an unknown solvent mol-ecule.

    PubMed

    Nogueira, Vanessa Senna; Bresolin, Leandro; Näther, Christian; Jess, Inke; de Oliveira, Adriano Bof

    2015-12-01

    The reaction between the racemic mixture of the camphor-4-phenyl-thio-semicarbazone derivative and cadmium acetate dihydrate yielded the title compound, [Cd(C17H20N3OS)2]. The Cd(II) ion is six-coordinated in a distorted octa-hedral environment by two deprotonated thio-semicarbazone ligands acting as an O,N,S-donor in a tridentate chelating mode, forming five-membered chelate rings. In the crystal, the mol-ecules are connected via pairs of N-H⋯S and C-H⋯S inter-actions, building centrosymmetric dimers. One of the ligands is disordered in the campher unit over two sets of sites with site-occupancy factors of 0.7 and 0.3. The structure contains additional solvent mol-ecules, which are disordered and for which no reasonable split model was found. Therefore, the data were corrected for disordered solvent using the SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9-18] in PLATON. Since the disordered solvents were removed by data processing, and the number of solvent entities was a suggestion only, they were not considered in the chemical formula and subsequent chemical or crystal information.

  8. Crystal structure of an unknown solvate of {2,2'-[ethane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato-κ(4) O,N,N',O'}(N-ferrocenylisonicotinamide-κN (1))cobalt(II): a Co(II)-salen complex that forms hydrogen-bonded dimers.

    PubMed

    Brautigam, Bryan; Herholdt, Chelsea; Farnsworth, William; Brudi, Ellen; McDonald, Eric; Wu, Guang; Contakes, Stephen

    2015-09-01

    The title compound, [CoFe(C5H5)(C16H14N2O2)(C11H9N2O)], was prepared as an air-stable red-brown solid by mixing equimolar amounts of {2,2'-[ethane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato}cobalt(II) and N-ferrocenylisonicotinamide in dry di-chloro-methane under nitro-gen and was characterized by ESI-MS, IR, and single-crystal X-ray diffraction. The structure at 100 K has triclinic (P-1) symmetry and indicates that the complex crystallizes as a mixture of λ and δ conformers. It exhibits the expected square pyramidal geometry about Co, and forms hydrogen-bonded dimers through amide N-H groups and phenolate O atoms on an adjacent mol-ecule. The involvement of only half of the salen ring structure in hydrogen-bonding inter-actions results in slight folding of the salen ring away from the pyridine coordination site in the δ conformer with an inter-salicyl-idene fold angle of 9.9 (7)°. In contrast, the λ conformer is nearly planar. The dimers pack into an open structure containing channels filled with highly disordered solvent mol-ecules. These solvent molecules' contributions to the intensity data were removed with the SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9-18] available in PLATON.

  9. Mean square atomic displacements of LaFe4Sb12

    NASA Astrophysics Data System (ADS)

    Feldman, Joseph; Singh, David

    2005-03-01

    Calculations in the harmonic approximation of the mean square atomic displacements (MSDs) for the filled skutterudite, LaFe4Sb12, are discussed, where the first-principles based force constant model that we recently proposed for this material is employed.^1 The various values of MSDs at high temperatures are as expected, following the differences in coordination and short range force constants. The results are primarily compared with temperature dependent neutron diffraction measurements^2 of MSDs in La.75Fe3CoSb12. The differences between theory and experiment are interpreted in terms of static disorder contributions to the MSDs. In the case of the isotropic MSDs, the resulting static disorder contributions are comparable to the corresponding minimum values previously obtained^2 from a data analysis, and both the Sb and Fe values are small compared to the La value of 0.0045å^2. Nevertheless the anisotropy in the Sb static disorder is large on the basis of our analysis, and in the direction of the neighboring La site the Sb disorder parameter is comparable to the above value for La. Finally, the effect of La interactions on the Sb- and Fe-MSDs is discussed within the context of our model, as is an Einstein model, fitted to the calculated La MSD. 1. J.L. Feldman et al., Phys. Rev. B 68, 094301 (2003).2. B.C. Chakoumakos et al., Acta Cryst. B 55,341 (1999).

  10. Enhanced rigid-bond restraints

    SciTech Connect

    Thorn, Andrea; Dittrich, Birger; Sheldrick, George M.

    2012-07-01

    An extension is proposed to the rigid-bond description of atomic thermal motion in crystals. The rigid-bond model [Hirshfeld (1976 ▶). Acta Cryst. A32, 239–244] states that the mean-square displacements of two atoms are equal in the direction of the bond joining them. This criterion is widely used for verification (as intended by Hirshfeld) and also as a restraint in structure refinement as suggested by Rollett [Crystallographic Computing (1970 ▶), edited by F. R. Ahmed et al., pp. 167–181. Copenhagen: Munksgaard]. By reformulating this condition, so that the relative motion of the two atoms is required to be perpendicular to the bond, the number of restraints that can be applied per anisotropic atom is increased from about one to about three. Application of this condition to 1,3-distances in addition to the 1,2-distances means that on average just over six restraints can be applied to the six anisotropic displacement parameters of each atom. This concept is tested against very high resolution data of a small peptide and employed as a restraint for protein refinement at more modest resolution (e.g. 1.7 Å)

  11. A monoclinic polymorph of [(Z)-N-(3-chloro­phen­yl)-O-methyl­thio­carbamato-κS](tri­phenyl­phosphane-κP)gold(I): crystal structure and Hirshfeld surface analysis

    PubMed Central

    Yeo, Chien Ing; Tan, Sang Loon; Tiekink, Edward R. T.

    2016-01-01

    The title compound, [Au(C8H7ClNOS)(C18H15P)], is a monoclinic (P21/n, Z′ = 1; form β) polymorph of the previously reported triclinic form (P-1, Z′ = 1; form α) [Tadbuppa & Tiekink (2010 ▸). Acta Cryst. E66, m664]. The mol­ecular structures of both forms feature an almost linear gold(I) coordination geometry [P—Au—S = 175.62 (5)° in the title polymorph], being coordinated by thiol­ate S and phosphane P atoms, a Z conformation about the C=N bond and an intra­molecular Au⋯O contact. The major conformational difference relates to the relative orientations of the residues about the Au—S bond: the P—Au—S—C torsion angles are −8.4 (7) and 106.2 (7)° in forms α and β, respectively. The mol­ecular packing of form β features centrosymmetric aggregates sustained by aryl-C—H⋯O inter­actions, which are connected into a three-dimensional network by aryl-C—H⋯π contacts. The Hirshfeld analysis of forms α and β shows many similarities with the notable exception of the influence of C—H⋯O inter­actions in form β. PMID:27536384

  12. Diosgenin hemihydrate

    PubMed Central

    Hernández Linares, María-Guadalupe; Bernès, Sylvain; Flores-Alamo, Marcos; Guerrero-Luna, Gabriel; Martínez-Gallegos, Anselmo A.

    2012-01-01

    Diosgenin [or (22R,25R)-spirost-5-en-3β-ol] is the starting material of the Marker degradation, a cheap semi-synthesis of progesterone, which has been designated as an Inter­national Historic Chemical Landmark. Thus far, a single X-ray structure for diosgenin is known, namely its dimethyl sulfoxide solvate [Zhang et al. (2005 ▶). Acta Cryst. E61, o2324–o2325]. We have now determined the structure of the hemihydrate, C27H42O3·0.5H2O. The asymmetric unit contains two diosgenin mol­ecules, with quite similar conformations, and one water mol­ecule. Hy­droxy groups in steroids and water mol­ecules form O—H⋯O hydrogen-bonded R 5 4(10) ring motifs. Fused edge-sharing R(10) rings form a backbone oriented along [100], which aggregates the diosgenin mol­ecules in the crystal structure. PMID:22904823

  13. Crystal structure of lead(II) tartrate: a redetermination.

    PubMed

    Weil, Matthias

    2015-01-01

    Single crystals of poly[μ4-tartrato-κ(6) O (1),O (3):O (1'):O (2),O (4):O (4')-lead], [Pb(C4H4O6)] n , were grown in a gel medium. In comparison with the previous structure determination of this compound from laboratory powder X-ray diffraction data [De Ridder et al. (2002 ▶). Acta Cryst. C58, m596-m598], the redetermination on the basis of single-crystal data reveals the absolute structure, all atoms with anisotropic displacement parameters and a much higher accuracy in terms of bond lengths and angles. It could be shown that a different space group or incorporation of water as reported for similarly gel-grown lead tartrate crystals is incorrect. In the structure, each Pb(2+) cation is bonded to eight O atoms of five tartrate anions, while each tartrate anion links four Pb(2+) cations. The resulting three-dimensional framework is stabilized by O-H⋯O hydrogen bonds between the OH groups of one tartrate anion and the carboxyl-ate O atoms of adjacent anions.

  14. Crystal structure of Sc1.91In1.39Mo15Se19, containing Mo6 and Mo9 clusters

    PubMed Central

    Gougeon, Patrick; Gall, Philippe; Salloum, Diala

    2015-01-01

    The structure of scandium indium penta­deca­molybdenum nona­deca­selenide, Sc1.91In1.39Mo15Se19, is isotypic with In2.9Mo15Se19 [Grüttner et al. (1979 ▸). Acta Cryst. B35, 285–292]. It is characterized by two cluster units Mo6Sei 8Sea 6 and Mo9Sei 11Sea 6 (where i represents inner and a apical atoms) that are present in a 1:1 ratio. The cluster units are centered at Wyckoff positions 2b and 2c and have point-group symmetry -3 and -6, respectively. The clusters are inter­connected through additional Mo—Se bonds. Sc—Se and In—Se bonds complete the structural set-up. In the title compound, the Sc3+ cations replace the trivalent indium atoms present in In2.9Mo15Se19, and a deficiency is observed at the monovalent indium site. One Mo, one Se and the Sc atom are situated on mirror planes, whereas two other Se atoms and the In atom are situated on threefold rotation axes. PMID:26279861

  15. Protein energy landscapes determined by five-dimensional crystallography

    SciTech Connect

    Schmidt, Marius; Srajer, Vukica; Henning, Robert; Ihee, Hyotcherl; Purwar, Namrta; Tenboer, Jason; Tripathi, Shailesh

    2013-12-01

    Barriers of activation within the photocycle of a photoactive protein were extracted from comprehensive time courses of time resolved crystallographic data collected at multiple temperature settings. Free-energy landscapes decisively determine the progress of enzymatically catalyzed reactions [Cornish-Bowden (2012 ▶), Fundamentals of Enzyme Kinetics, 4th ed.]. Time-resolved macromolecular crystallography unifies transient-state kinetics with structure determination [Moffat (2001 ▶), Chem. Rev.101, 1569–1581; Schmidt et al. (2005 ▶), Methods Mol. Biol.305, 115–154; Schmidt (2008 ▶), Ultrashort Laser Pulses in Medicine and Biology] because both can be determined from the same set of X-ray data. Here, it is demonstrated how barriers of activation can be determined solely from five-dimensional crystallography, where in addition to space and time, temperature is a variable as well [Schmidt et al. (2010 ▶), Acta Cryst. A66, 198–206]. Directly linking molecular structures with barriers of activation between them allows insight into the structural nature of the barrier to be gained. Comprehensive time series of crystallographic data at 14 different temperature settings were analyzed and the entropy and enthalpy contributions to the barriers of activation were determined. One hundred years after the discovery of X-ray scattering, these results advance X-ray structure determination to a new frontier: the determination of energy landscapes.

  16. Can I solve my structure by SAD phasing? Planning an experiment, scaling data and evaluating the useful anomalous correlation and anomalous signal.

    PubMed

    Terwilliger, Thomas C; Bunkóczi, Gábor; Hung, Li Wei; Zwart, Peter H; Smith, Janet L; Akey, David L; Adams, Paul D

    2016-03-01

    A key challenge in the SAD phasing method is solving a structure when the anomalous signal-to-noise ratio is low. Here, algorithms and tools for evaluating and optimizing the useful anomalous correlation and the anomalous signal in a SAD experiment are described. A simple theoretical framework [Terwilliger et al. (2016), Acta Cryst. D72, 346-358] is used to develop methods for planning a SAD experiment, scaling SAD data sets and estimating the useful anomalous correlation and anomalous signal in a SAD data set. The phenix.plan_sad_experiment tool uses a database of solved and unsolved SAD data sets and the expected characteristics of a SAD data set to estimate the probability that the anomalous substructure will be found in the SAD experiment and the expected map quality that would be obtained if the substructure were found. The phenix.scale_and_merge tool scales unmerged SAD data from one or more crystals using local scaling and optimizes the anomalous signal by identifying the systematic differences among data sets, and the phenix.anomalous_signal tool estimates the useful anomalous correlation and anomalous signal after collecting SAD data and estimates the probability that the data set can be solved and the likely figure of merit of phasing. PMID:26960123

  17. Crystal structure of 2-[(3S,4S)-4-(anthracen-9-yl)-1-(4-meth-oxy-phen-yl)-2-oxoazetidin-3-yl]-2-aza-2H-phenalene-1,3-dione unknown solvate.

    PubMed

    Çelik, Ísmail; Akkurt, Mehmet; Jarrahpour, Aliasghar; Rad, Javad Ameri; Çelik, Ömer

    2015-03-01

    The central β-lactam ring of the title compound, C36H24N2O4, is almost planar (r.m.s. deviation = 0.003 Å) and makes dihedral angles of 17.17 (19), 89.76 (17) and 78.44 (17)° with the benzene ring, the anthracene ring (r.m.s. deviation = 0.003 Å) and the 1H-benzo[de]iso-quinoline-1,3(2H)-dione moiety, which is nearly planar [maximum deviation = 0.098 (2) Å], respectively. The mol-ecular structure is stabilized by an intra-molecular C-H⋯N hydrogen bond. In the crystal, mol-ecules are linked via C-H⋯π and π-π stacking inter-actions [centroid-centroid distances = 3.5270 (19) and 3.779 (2) Å], forming a three-dimensional structure. A region of disordered electron density, probably disordered solvent mol-ecules, was treated with the SQUEEZE procedure in PLATON [Spek (2015 ▶). Acta Cryst. C71, 9-18], which indicated a solvent cavity of 322 Å(3) containing approximately 91 electrons. Their formula mass and unit-cell characteristics were not taken into account during the refinement. PMID:25844239

  18. Crystal structure of 2-methyl-amino-4-(6-methyl-4-oxo-4H-chromen-3-yl)-3-nitro-pyrano[3,2-c]chromen-5(4H)-one with an unknown solvate.

    PubMed

    Raja, Rajamani; Kandhasamy, Subramani; Perumal, Paramasivam T; SubbiahPandi, A

    2015-09-01

    In the title compound, C23H16N2O7, the mean planes of the two chromene units (r.m.s. deviations = 0.031 and 0.064 Å) are almost normal to one another with a dihedral angle of 85.59 (6)°. The central six-membered pyran ring has a distorted envelope conformation, with the methine C atom at the flap. There is an intra-molecular N-H⋯O hydrogen bond, which generates an S(6) ring motif. In the crystal, mol-ecules are linked by pairs of N-H⋯O hydrogen bonds, forming inversion dimers with an R 2 (2)(12) ring motif. The dimers are linked by pairs of C-H⋯O hydrogen bonds, enclosing R 2 (2)(6) ring motifs, forming zigzag chains along [001]. The chains are linked by a second pair of C-H⋯O hydrogen bonds, forming slabs parallel to (110). Within the slabs there are C-H⋯π inter-actions present. A region of disordered electron density was treated with the SQUEEZE procedure in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18] following unsuccessful attempts to model it as plausible solvent mol-ecule(s). The given chemical formula and other crystal data do not take into account the unknown solvent mol-ecule(s). PMID:26396882

  19. Crystal structure of tri-aqua-(2,6-di-methyl-pyrazine-κN (4))bis-(thio-cyanato-κN)manganese(II) 2,5-di-methyl-pyrazine disolvate.

    PubMed

    Suckert, Stefan; Wöhlert, Susanne; Jess, Inke; Näther, Christian

    2015-12-01

    In the crystal structure of the title complex, [Mn(NCS)2(C6H8N2)(H2O)3]·2C6H8N2, the Mn(II) cation is coordinated by two terminally N-bonded thio-cyanate anions, three water mol-ecules and one 2,6-di-methyl-pyrazine ligand within a slightly distorted N3O3 octa-hedral geometry; the entire complex mol-ecule is generated by the application of a twofold rotation axis. The asymmetric unit also contains an uncoordinating 2,5-di-methyl-pyrazine ligand in a general position. Obviously, the coordination to the 2,6-di-methyl-pyrazine ligand is preferred because coordination to the 2,5-di-methyl-pyrazine is hindered due to the bulky methyl group proximate to the N atom. The discrete complexes are linked by water-O-H⋯N(2,6-di-methyl-pyzazine/2,5-di-methyl-pyza-zine) hydrogen bonding, forming a three-dimensional network. In the crystal, mol-ecules are arranged in a way that cavities are formed in which unspecified, disordered solvent molecules reside. These were modelled employing the SQUEEZE routine in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The composition of the unit cell does not take into account the presence of the unspecified solvent. PMID:26870435

  20. Crystal structure of an unknown solvate of {2,2'-[ethane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato-κ(4) O,N,N',O'}(N-ferrocenylisonicotinamide-κN (1))cobalt(II): a Co(II)-salen complex that forms hydrogen-bonded dimers.

    PubMed

    Brautigam, Bryan; Herholdt, Chelsea; Farnsworth, William; Brudi, Ellen; McDonald, Eric; Wu, Guang; Contakes, Stephen

    2015-09-01

    The title compound, [CoFe(C5H5)(C16H14N2O2)(C11H9N2O)], was prepared as an air-stable red-brown solid by mixing equimolar amounts of {2,2'-[ethane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato}cobalt(II) and N-ferrocenylisonicotinamide in dry di-chloro-methane under nitro-gen and was characterized by ESI-MS, IR, and single-crystal X-ray diffraction. The structure at 100 K has triclinic (P-1) symmetry and indicates that the complex crystallizes as a mixture of λ and δ conformers. It exhibits the expected square pyramidal geometry about Co, and forms hydrogen-bonded dimers through amide N-H groups and phenolate O atoms on an adjacent mol-ecule. The involvement of only half of the salen ring structure in hydrogen-bonding inter-actions results in slight folding of the salen ring away from the pyridine coordination site in the δ conformer with an inter-salicyl-idene fold angle of 9.9 (7)°. In contrast, the λ conformer is nearly planar. The dimers pack into an open structure containing channels filled with highly disordered solvent mol-ecules. These solvent molecules' contributions to the intensity data were removed with the SQUEEZE procedure [Spek (2015). Acta Cryst. C71, 9-18] available in PLATON. PMID:26396858

  1. Mol-ecular and crystal structure of gossypol tetra-methyl ether with an unknown solvate.

    PubMed

    Honkeldieva, Muhabbat; Talipov, Samat; Mardanov, Rustam; Ibragimov, Bakhtiyar

    2015-02-01

    The title compound, C34H38O8 (systematic name: 5,5'-diisopropyl-2,2',3,3'-tetra-meth-oxy-7,7'-dimethyl-2H,2'H-8,8'-bi-[naphtho-[1,8-bc]furan]-4,4'-diol), has been obtained from a gossypol solution in a mixture of dimethyl sulfate and methanol. The mol-ecule is situated on a twofold rotation axis, so the asymmetric unit contains one half-mol-ecule. In the mol-ecule, the hy-droxy groups are involved in intra-molecular O-H⋯O hydrogen bonds, and the two naphthyl fragments are inclined each to other by 83.8 (1)°. In the crystal, weak C-H⋯O and C-H⋯π inter-actions consolidate the packing, which exhibits channels with an approximate diameter of 6 Å extending along the c-axis direction. These channels are filled with highly disordered solvent mol-ecules, so their estimated scattering contribution was subtracted from the observed diffraction data using the SQUEEZE option in PLATON [Spek, A. L. (2015). Acta Cryst. C71, 9-18]. PMID:25878814

  2. Crystal structure of an unknown solvate of bis-(tetra-n-butyl-ammonium) [N,N'-(4-tri-fluoro-methyl-1,2-phenyl-ene)bis-(oxamato)-κ(4) O,N,N',O']nickelate(II).

    PubMed

    Eya'ane Meva, François; Schaarschmidt, Dieter; Rüffer, Tobias

    2015-06-01

    In the title compound, [N(C4H9)4]2[Ni(C11H3F3N2O6)] or [N(n-Bu)4]2[Ni(topbo)] [n-Bu = n-butyl and topbo = 4-tri-fluoro-methyl-1,2-phenyl-enebis(oxamate)], the Ni(2+) cation is coordinated by two deprotonated amido N atoms and two carboxyl-ate O atoms, setting up a slightly distorted square-planar coordination environment. The [Ni(topbo](2-) anion lies on a twofold rotation axis. Due to an incompatibility with the point-group symmetry of the complete mol-ecule, orientational disorder of the CF3 group is observed. The tetra-hedral ammonium cations and the anion are linked by weak inter-molecular C-H⋯O and C-H⋯F hydrogen-bonding inter-actions into a three-dimensional network. A region of electron density was treated with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9-18] following unsuccessful attempts to model it as plausible solvent mol-ecule(s). The given chemical formula and other crystal data do not take into account the unknown solvent mol-ecule. PMID:26090126

  3. Crystal structure of ethyl 3-amino-6-methyl-2-[(4-methyl-phen-yl)carbamo-yl]-4-[(E)-2-phenyl-ethen-yl]thieno[2,3-b]pyridine-5-carboxyl-ate monohydrate.

    PubMed

    Mague, Joel T; Akkurt, Mehmet; Mohamed, Shaaban K; Bakhite, Etify A; Albayati, Mustafa R

    2016-03-01

    In the title mol-ecule, C27H25N3O3S·H2O, the dihedral angle between the planes of the thienyl ring and the pendant p-tolyl group is 39.25 (6)°, while that between the pyridine ring and the pendant phenyl ring is 44.37 (6)°. In addition, there is a slight twist in the bicyclic core, with a dihedral angle of 2.39 (4)° between the thienyl and pyridine rings. The conformation of the carbamoyl moiety is partially determined by an intra-molecular N-H⋯O hydrogen bond. In the crystal, complementary N-H⋯O hydrogen bonds form dimers which are then associated into chains parallel to the c axis through O-H⋯N hydrogen bonds involving the water mol-ecule of crystallization. Electron density associated with an additional solvent mol-ecule of partial occupancy and disordered about a twofold axis was removed with the SQUEEZE procedure in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The given chemical formula and other crystal data do not take into account the unknown solvent molecule(s). PMID:27006791

  4. Crystal structure of an unknown tetra-hydro-furan solvate of tetra-kis-(μ 3-cyanato-κ(3) N:N:N)tetra-kis-[(triphenyl-phosphane-κP)-silver(I)].

    PubMed

    Frenzel, Peter; Schaarschmidt, Dieter; Jakob, Alexander; Lang, Heinrich

    2015-10-01

    In the title compound, [{[(C6H5)3P]Ag}4{NCO}4], a distorted Ag4N4-heterocubane core is set up by four Ag(I) ions being coordinated by the N atoms of the cyanato anions in a μ 3-bridging mode. In addition, a tri-phenyl-phosphine ligand is datively bonded to each of the Ag(I) ions. Intra-molecular Ag⋯Ag distances as short as 3.133 (9) Å suggest the presence of argentophilic (d (10)⋯d (10)) inter-actions. Five moderate-to-weak C-H⋯O hydrogen-bonding inter-actions are observed in the crystal structure, spanning a three-dimensional network. A region of electron density was treated with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9-18] following unsuccessful attempts to model it as being part of disordered tetra-hydro-furan solvent mol-ecules. The given chemical formula and other crystal data do not take into account these solvent mol-ecules. PMID:26594421

  5. Crystal structure of the Anderson-type hetero­polyoxometalate; K2[H7CrIIIMo6O24]·8H2O: a redetermination revealing the position of the extra H atom in the polyanion

    PubMed Central

    Joo, Hea-Chung; Park, Ki-Min; Lee, Uk

    2015-01-01

    The title compound contains a symmetric hydrogen bond in which the H atom does not lie on a crystallographic centre of symmetry. The structure of K2[H7CrIIIMo6O24]·8H2O, namely dipotassium hepta­hydrogen hexa­molybdochromate(III) octa­hydrate, previously reported by Lee [Acta Cryst. (2007), E63, i5–i7], has been redetermined in order to locate the position of the seventh H atom in the anion. Six of the H atoms are bonded to the six μ3-O atoms and form hydrogen bonds of medium strength either to water mol­ecules or to the terminal O atoms of other polyanions. The seventh H atom forms a very short hydrogen bond between two μ2-O atoms on adjacent polyanions. This short bond, together with two normal hydrogen bonds, link the two crystallographically distinct centrosymmetric polyanions into chains along [011], while the length of this bond [2.461 (3) Å] suggests that the H atom lies at its centre, but unusually for such a bond, this point is not a crystallographic centre of symmetry. PMID:25878807

  6. Bis[2-(hy-droxy-imino-meth-yl)phenolato]nickel(II): a second monoclinic polymorph.

    PubMed

    Rusanova, Julia A; Buvaylo, Elena A; Rusanov, Eduard B

    2011-01-01

    The title compound, [Ni(C(7)H(6)NO(2))(2)], (I), is a second monoclinic polymorph of the compound, (II), reported by Srivastava et al. [Acta Cryst. (1967), 22, 922] and Mereiter [Private communication (2002) CCDC refcode NISALO01]. The bond lengths and angles are similar in both structures. The mol-ecule in both structures lies on a crystallographic inversion center and both have an inter-nal hydrogen bond. The title compound crystallizes in the space group P2(1)/c (Z = 2), whereas compound (II) is in the space group P2(1)/n (Z = 2) with a similar cell volume but different cell parameters. In both polymorphs, mol-ecules are arranged in the layers but in contrast to the previously published compound (II) where the dihedral angle between the layers is 86.3°, in the title polymorph the same dihedral angle is 29.4°. The structure of (I) is stabilized by strong intra-molecular O-H⋯O hydrogen bonding between the O-H group and the phenolate O atom. PMID:21522882

  7. Crystal structure of 1,2-bis-[(2-tert-butyl-phen-yl)imino]-ethane.

    PubMed

    Silvino, Alexandre C; Torres, Juliana M

    2015-06-01

    The whole molecule of the title compound, C22H28N2, (I), is generated by inversion symmetry. The mol-ecule is rather similar to that of 2,3-bis-[(2-tert-butyl-phen-yl)imino]-butane, (II), a di-imine ligand comprising similar structural features [Ferreira et al. (2006 ▶). Acta Cryst. E62, o4282-o4284]. Both ligands crystallize with the -N=C(R)-C(R)=N- group around an inversion centre, in a trans configuration. Comparing the two structures, it may be noted that the independent planar groups in both mol-ecules [the central link, -N=C(R)-C(R)=N-, and the terminal aromatic ring] subtend an angle of 69.6 (1)° in (II) and 49.4 (2)° in (I). Ferreira and co-workers proposed that such angle deviation may be ascribed to the presence of two non-classical intra-molecular hydrogen bonds and steric factors. In fact, in (I), similar non-classical hydrogen bonds are observed, and the larger angular deviation in (II) may be assigned to the presence of methyl groups in the di-imino fragment, which can cause steric hindrance due to the presence of bulky tert-butyl substituents in the aromatic rings. The C=N bond lengths are similar in both compounds and agree with comonly accepted values. PMID:26090180

  8. A redetermination from the original data of the crystal structure of 2-amino-4,6-di­meth­oxy­pyrimidin-1-ium 4-amino­benzoate

    PubMed Central

    Fábry, Jan

    2016-01-01

    The title structure, C6H9.5N3O2 0.5+·C7H6.5NO2 0.5−, which might be named schematically as 2-amino-4,6-di­meth­oxy­pyrimidine-(μ2-hydrogen)-4-amino­benzoate to indicate a bridging H atom, has been redetermined from the data published by Thanigaimani, Mu­thiah & Lynch [Acta Cryst. (2006), E62, o2976–o2978]. The improvement of the present redetermination consists in a released geometry of the primary amine groups, which were originally assumed to be planar, as well as in a redetermination of the position of the hy­droxy H atom. This H atom, whose parameters were originally constrained, turns out to be situated about the centre of the O⋯N hydrogen bond in two disordered positions with occupancies of 0.5 each. PMID:27375878

  9. Protein energy landscapes determined by five-dimensional crystallography

    PubMed Central

    Schmidt, Marius; Srajer, Vukica; Henning, Robert; Ihee, Hyotcherl; Purwar, Namrta; Tenboer, Jason; Tripathi, Shailesh

    2013-01-01

    Free-energy landscapes decisively determine the progress of enzymatically catalyzed reactions [Cornish-Bowden (2012 ▶), Fundamentals of Enzyme Kinetics, 4th ed.]. Time-resolved macromolecular crystallography unifies transient-state kinetics with structure determination [Moffat (2001 ▶), Chem. Rev. 101, 1569–1581; Schmidt et al. (2005 ▶), Methods Mol. Biol. 305, 115–154; Schmidt (2008 ▶), Ultrashort Laser Pulses in Medicine and Biology] because both can be determined from the same set of X-ray data. Here, it is demonstrated how barriers of activation can be determined solely from five-dimensional crystallo­graphy, where in addition to space and time, temperature is a variable as well [Schmidt et al. (2010 ▶), Acta Cryst. A66, 198–206]. Directly linking molecular structures with barriers of activation between them allows insight into the structural nature of the barrier to be gained. Comprehensive time series of crystallo­graphic data at 14 different temperature settings were analyzed and the entropy and enthalpy contributions to the barriers of activation were determined. One hundred years after the discovery of X-ray scattering, these results advance X-ray structure determination to a new frontier: the determination of energy landscapes. PMID:24311594

  10. Theoretical study of the properties of X-ray diffraction moiré fringes. I

    SciTech Connect

    Yoshimura, Jun-ichi

    2015-05-14

    A detailed and comprehensive theoretical description of X-ray diffraction moiré fringes for a bicrystal specimen is given on the basis of a calculation by plane-wave dynamical diffraction theory, where the effect of the Pendellösung intensity oscillation on the moiré pattern is explained in detail. A detailed and comprehensive theoretical description of X-ray diffraction moiré fringes for a bicrystal specimen is given on the basis of a calculation by plane-wave dynamical diffraction theory. Firstly, prior to discussing the main subject of the paper, a previous article [Yoshimura (1997 ▸). Acta Cryst. A53, 810–812] on the two-dimensionality of diffraction moiré patterns is restated on a thorough calculation of the moiré interference phase. Then, the properties of moiré fringes derived from the above theory are explained for the case of a plane-wave diffraction image, where the significant effect of Pendellösung intensity oscillation on the moiré pattern when the crystal is strained is described in detail with theoretically simulated moiré images. Although such plane-wave moiré images are not widely observed in a nearly pure form, knowledge of their properties is essential for the understanding of diffraction moiré fringes in general.

  11. Different forms of antiparallel stacking of hydrogen-bonded antidromic rings in the solid state: polymorphism with virtually the same unit cell and two-dimensional isostructurality with alternating layers.

    PubMed

    Kálmán, Alajos; Fábián, László; Argay, Gyula; Bernáth, Gábor; Gyarmati, Zsuzsanna Cs

    2004-12-01

    As a continuation of a systematic structural analysis of 2-hydroxycycloalkanecarboxylic acids and their carboxamide analogs, the effects of antidromic rings [Jeffrey & Saenger (1991). Hydrogen Bonding in Biological Structures. Berlin, Heidelberg: Springer Verlag] upon the layer stacking of cyclopentane and cycloheptane derivatives are compared. Determination of the structure of trans-2-hydroxycycloheptanecarboxylic acid (2) led to the discovery of two polymorphs with virtually the same unit cell [Kalman et al. (2003). J. Am. Chem. Soc. 125, 34-35]. (i) The layer stacking of the antidromic rings for the whole single crystal is antiparallel (2b). (ii) The antidromic rings and the 21 axis are parallel (2a), consequently the domains of the single crystal must be antiparallel. While their polymorphism is solvent-controlled, they illustrate a novel form of two-dimensional isostructurality. Antiparallel layer stacking is again demonstrated by trans-2-hydroxycycloheptanecarboxamide (3) (space group Pbca). It is built up from layers isostructural with those in the homologous trans-2-hydroxycyclopentanecarboxamide (4) [Kalman et al. (2001). Acta Cryst. B57, 539-550], but in this structure (space group Pca21) the layers are stacked in parallel mode. Similar to (2a) and (2b), the antiparallel layer stacking in (3) versus their parallel array in (4) illustrates the two-dimensional isostructurality with alternating layer orientations. Although (3) and (4) display isostructurality, they are not isomorphous.

  12. Theoretical study of the properties of X-ray diffraction moiré fringes. I

    PubMed Central

    Yoshimura, Jun-ichi

    2015-01-01

    A detailed and comprehensive theoretical description of X-ray diffraction moiré fringes for a bicrystal specimen is given on the basis of a calculation by plane-wave dynamical diffraction theory. Firstly, prior to discussing the main subject of the paper, a previous article [Yoshimura (1997 ▸). Acta Cryst. A53, 810–812] on the two-dimensionality of diffraction moiré patterns is restated on a thorough calculation of the moiré interference phase. Then, the properties of moiré fringes derived from the above theory are explained for the case of a plane-wave diffraction image, where the significant effect of Pendellösung intensity oscillation on the moiré pattern when the crystal is strained is described in detail with theoretically simulated moiré images. Although such plane-wave moiré images are not widely observed in a nearly pure form, knowledge of their properties is essential for the understanding of diffraction moiré fringes in general. PMID:25970298

  13. Refinement of the crystal structural parameters of the intermediate phase of h-BaTiO3 using convergent-beam electron diffraction.

    PubMed

    Ogata, Yoichiro; Tsuda, Kenji; Akishige, Yukikuni; Tanaka, Michiyoshi

    2004-11-01

    Crystal structural parameters (21 positional parameters and nine isotropic Debye-Waller factors) of the intermediate phase of hexagonal barium titanate (h-BaTiO3) have been refined by a structure analysis method using convergent-beam electron diffraction (CBED); this method was developed by Tsuda & Tanaka [Acta Cryst. (1999), A55, 939-954]. In order to perform the analysis, a parallel computation using a computer cluster composed of 16 connected Pentium 4 PCs was introduced. A function of parallel computation has been implemented in our analysis software, MBFIT, with the aid of the Message Passing Interface (MPI). Parallel computation enabled the present refinement to be conducted using a [001] CBED pattern and a [010] CBED pattern simultaneously. Reliable errors for the refined structural parameters have been obtained from the analyses of four independent experimental data sets instead of using the errors obtained by the error-propagation rule of least-squares fitting. The parameters obtained have been found to agree well with those determined by a neutron Rietveld analysis.

  14. Phase determination by wavelength-modulated diffraction. I. Centrosymmetric case.

    PubMed

    Koganezawa, T; Yoshimura, Y; Nakamura, N; Iwasaki, H

    2001-05-01

    Wavelength-modulated diffraction was developed by Iwasaki, Yurugi & Yoshimura [Acta Cryst. (1999), A55, 864-870] as a method for phase determination, in which the intensity of Bragg reflections is recorded using radiation whose wavelength is changing continually over a range in the vicinity of the absorption edge of an atom in the crystal. Using a ferrocene derivative crystal (chemical formula C36H32O7Fe, space group P2(1)/a) with the Fe atoms chosen as anomalous scatterers, measurements were made of the intensity gradient dI/d lambda of the reflections with an imaging plate as a detector on a synchrotron radiation source at Ritsumeikan University. In the case of a centrosymmetric crystal, the phase of the structure factor could be derived by measuring only the sign of dI/d lambda at one wavelength in the range. Of 104 reflections measured, the correct phase was assigned to 101 reflections. A discussion is given on the errors involved and on the limits of application of the method.

  15. A new phasing method based on the principle of minimum charge.

    PubMed

    Kalugin, P

    2001-11-01

    A new method for phase determination in X-ray crystallography is proposed. The method is based on the so-called 'minimum-charge' principle, recently suggested by Elser [Acta Cryst. (1999), A55, 489-499]. The electron-density function rho is sought in the form rho(x) = /psi(x)/2, where psi is an n-component real function. The norm integral/psi(x)/2dx is minimized under the constraint imposed by the measured data on the amplitudes of Fourier harmonics of rho. Compared with the straightforward implementation of the 'minimum-charge' scheme, the method attenuates the Gibbs phenomenon and is also capable of extrapolation of the diffraction data beyond the set of measured amplitudes. The method is applicable to quasicrystals under the condition that the number of components n of the function psi is bigger than the dimensionality of the 'atomic surface'. It has been successfully tested on synthetic data for a Fibonacci chain and octagonal tiling. In the latter case, the reconstructed density map shows the shape of the atomic surface, despite relatively low resolution data.

  16. Enumeration of four-connected three-dimensional nets. III. Conversion of edges of three-connected two-dimensional nets into saw chains.

    PubMed

    Han; Smith

    1999-03-01

    A three-repeat saw (s) chain has each vertical edge separated by a tooth composed of two tilted edges zig and zag. Some horizontal (h) edges from a parallel stack of three-connected two-dimensional (2D) nets can be converted into an s chain. Each resulting four-connected vertex in the three-dimensional (3D) net may be part of either one, two or three s chains. The first type of (h,s)* 3D net is related by a sigma-type mirror plane to a (h,z)* net listed in paper II [Han & Smith (1998). Acta Cryst. A55, 342-359]. The second type does not have an (h,z)* relative. Using the same three-connected 2D nets as in paper II, 174 four-connected 3D nets were selected from the first two types, including six in known structures: 'nepheline hydrate' (International Zeolite Association Structure Commission code JBW), AlPO(4)-12-TAMU (ATT), offretite (OFF), Linde Type L (LTL), SUZ-4 (SZF) and ZSM-10 (ZST). The third type with three back-to-back s chains is represented by edingtonite (EDI), and systematic enumeration is in progress. The geometrical and topological properties of the 3D nets are given. Idealized unit-cell data and atomic coordinates for tetrahedral bonding were obtained for 40 selected 3D nets by distance-least-squares (DLS) refinement.

  17. Orientation relationship of eutectoid FeAl and FeAl2

    PubMed Central

    Scherf, A.; Kauffmann, A.; Kauffmann-Weiss, S.; Scherer, T.; Li, X.; Stein, F.; Heilmaier, M.

    2016-01-01

    Fe–Al alloys in the aluminium range of 55–65 at.% exhibit a lamellar microstructure of B2-ordered FeAl and triclinic FeAl2, which is caused by a eutectoid decomposition of the high-temperature Fe5Al8 phase, the so-called ∊ phase. The orientation relationship of FeAl and FeAl2 has previously been studied by Bastin et al. [J. Cryst. Growth (1978 ▸), 43, 745] and Hirata et al. [Philos. Mag. Lett. (2008 ▸), 88, 491]. Since both results are based on different crystallographic data regarding FeAl2, the data are re-evaluated with respect to a recent re-determination of the FeAl2 phase provided by Chumak et al. [Acta Cryst. (2010 ▸), C66, i87]. It is found that both orientation relationships match subsequent to a rotation operation of 180° about a 〈112〉 crystallographic axis of FeAl or by applying the inversion symmetry of the FeAl2 crystal structure as suggested by the Chumak data set. Experimental evidence for the validity of the previously determined orientation relationships was found in as-cast fully lamellar material (random texture) as well as directionally solidified material (∼〈110〉FeAl || solidification direction) by means of orientation imaging microscopy and global texture measurements. In addition, a preferential interface between FeAl and FeAl2 was identified by means of trace analyses using cross sectioning with a focused ion beam. On the basis of these habit planes the orientation relationship between the two phases can be described by (01)FeAl || (114) and [111]FeAl || [10]. There is no evidence for twinning within FeAl lamellae or alternating orientations of FeAl lamellae. Based on the determined orientation and interface data, an atomistic model of the structure relationship of Fe5Al8, FeAl and FeAl2 in the vicinity of the eutectoid decomposition is derived. This model is analysed with respect to the strain which has to be accommodated at the interface of FeAl and FeAl2. PMID:27047304

  18. Comments on "Synthesis aspects, structural, spectroscopic, antimicrobial and room temperature ferromagnetism of zinc iodide complex with Schiff based ligand" by K. Shakila and S. Kalainathan, Spectrochim. Acta 135 A (2015) 1059-1065

    NASA Astrophysics Data System (ADS)

    Srinivasan, Bikshandarkoil R.; Nadkarni, V. S.

    2016-06-01

    Shakila and Kalainathan report on the synthetic and structural aspects of a zinc iodide complex with Schiff based ligand, which exhibits room temperature ferromagnetism. In this comment, many points of criticism, concerning the characterization of this so called zinc iodide complex of Schiff based ligand are highlighted to prove that the title paper is completely erroneous.

  19. Corrigendum to "Basin-scale controls on the molybdenum-isotope composition of seawater during Oceanic Anoxic Event 2 (Late Cretaceous)" [Geochim. Cosmochim. Acta 178 (2016) 291-306

    NASA Astrophysics Data System (ADS)

    Dickson, Alexander J.; Jenkyns, Hugh C.; Porcelli, Donald; van den Boorn, Sander; Idiz, Erdem; Owens, Jeremy D.

    2016-09-01

    A recent molybdenum-isotope estimate of the extent of anoxic and euxinic conditions in the world ocean during Oceanic Anoxic Event 2 (∼94 Ma) concluded by discussing a contrast between the new results with existing estimates of marine euxinia based on sulphur isotopes. This suggested contrast was erroneous; when areal extents of marine anoxia and euxinia are calculated for both isotopic proxies, the agreement is actually striking, and highlights the fact that large areas of the global ocean probably remained well ventilated during this event.

  20. Corrigendum to "Recycling of crustal material by the Iceland mantle plume: New evidence from nitrogen elemental and isotope systematics of subglacial basalts" [Geochim. Cosmochim. Acta 176 (2016) 206-226

    NASA Astrophysics Data System (ADS)

    Halldórsson, Sæmundur A.; Hilton, David R.; Barry, Peter H.; Füri, Evelyn; Grönvold, Karl

    2016-08-01

    In Table 1 of the above published paper, N2/40Ar* ratios (column 13) are incorrect. A corrected table and updated figures (Figs. 6-8) are shown below. The correct N2/40Ar* values vary between 178 and 2.6 × 104, with a mean of 4.1 ± 2.1 (×103). Although this range in N2/40Ar* ratios is somewhat smaller compared to what was reported, it still displays considerably more heterogeneity compared to the DMM database. The new mean value is also significantly higher than the DMM mean (138 ± 65), as discussed. Therefore, the findings in the paper concerning heterogeneous and elevated N2/40Ar* ratios in Icelandic subglacial basalts still stand.

  1. WITHDRAWN: Corrigendum to "High-sensitive cardiac troponin I (hs-cTnl) values in patients with stable cardiovascular disease: An initial foray" [Clinica Chimica Acta 411 (2010) 812--817].

    PubMed

    Schulz, Olaf; Reinicke, Markus; Berghoefer, Gunnar H; Bensch, Ricarda; Kraemer, Jochen; Schimke, Ingolf; Jaffe, Allan S

    2010-05-18

    This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

  2. Comment on "theoretical acquirement of the red shift of nu(F-H) upon complexation with Ne" by Guoqun Liu and Xianxi Zhang [Spectrochim. Acta Part A 69 (2008) 917-920].

    PubMed

    McDowell, Sean A C

    2008-12-15

    This Comment shows that the agreement between theory and experiment for the vibrational red shift of the FH stretch upon complexation with Ne claimed by the authors of the captioned manuscript is not justified and should be considered as merely fortuitous.

  3. Corrigendum to ‘Evidence for shock heating and constraints on Martian surface temperatures revealed by 40Ar/39Ar thermochronometry of Martian meteorites’ [Geochim. Cosmochim. Acta (2010) 6900–6920

    SciTech Connect

    Cassata, William S.; Shuster, David L.; Renne, Paul R.; Weiss, Benjamin P.

    2014-10-23

    Here, the authors regret they have discovered errors in Eq. (3) and in a spreadsheet used to calculate cosmogenic exposure ages shown in Table 1. Eq. (3) is missing a term. The spreadsheet errors concerned an incorrect cell reference and application of Eq. (3). Correction of these errors results in ~15–20% changes to the exposure ages of all samples, minor (generally <0.2%) changes to the radioisotopic ages of some samples (those that entailed a correction for chlorine-derived 38Ar calculated based on the exposure age; see Section 3.3), and statistically insignificant changes to the inferred trapped components identified through isochron analyses. These modifications have no impact on the modeling, discussions, or conclusions in the paper, nor do the changes to radioisotopic ages exceed the 1 sigma uncertainties.

  4. Coping with Social Change: Programs That Work. Proceedings of a Conference (Acapulco, Mexico, June 1989) = Como enfrentarse al cambio social: programas eficaces. Actas de uno Conferencia (Acapulco, Mexico, Junio de 1989).

    ERIC Educational Resources Information Center

    Hoskins, Irene, Ed.

    Written in English and Spanish, this document contains the proceedings of the 14th International Congress of Gerontology on concerns about the impact of rapid social change on the well-being of older women and families in Latin American and the Caribbean and about effective programs that address the needs of the older populations. The first…

  5. Western Hemisphere Conference on Persons with Disabilities. Conference Proceedings (Washington, D.C., March 14-18, 1993) = Conferencia Hemisferica Occidental sobre Personas con Discapacidades. Actas de la Conferencia. (Washington, D.C., 14 al 18 de Marzo de 1993).

    ERIC Educational Resources Information Center

    Kelley, Jerry D., Ed.; And Others

    This document presents the proceedings of a conference which brought together delegates and First Ladies representing western hemisphere nations to address needs and issues affecting people with disabilities in the Americas. It presents the texts of two keynote addresses: "Small Triumphs, Big Victories: A Global View of Persons with Disabilities,"…

  6. Corrigendum to "Historical review: Anders Jonas Ångström and the foundation of spectroscopy - Commemorative article on the second centenary of his birth" [Spectrochim. Acta Part B, 102 (2014) 12-23

    NASA Astrophysics Data System (ADS)

    Reif-Acherman, Simón

    2015-07-01

    The following addendum should be added to the Acknowledgments of the above article. Due to the multiplicity of simultaneous activities in which I am continuously involved, I forgot mentioning that Prof. Dr. Klaus Hentschel, of the History Department of the University of Stuttgart (Germany) was helpful in obtaining some of the source material used in my review. In particular, Prof. Hentschel provided the scans of Anne Beckmann's work to which I was guided by passages in his book on "Mapping the spectrum", Oxford University Press (2002). I also followed his recommendation of contacting the Swedish historians of science, and Prof. Sven Widmalm among them; however, the correspondence was not successful.

  7. Comment on: ``FTIR and FTRaman spectra, assignments, ab initio HF and DFT analysis of 4-nitrotoluene'' by S. Ramalingam et al., Spectrochemica Acta A 75 (2010) 1308-1314

    NASA Astrophysics Data System (ADS)

    Tomkinson, John

    2010-10-01

    The title paper reports the ab initio calculated structure and vibrational spectra of 4-nitrotoluene. The calculated structure is wrong and the assignments are inconsistent with earlier work. We have recalculated the ab initio structure and reassigned the spectra in agreement with the standard text.

  8. Comment on: "FTIR and FTRaman spectra, assignments, ab initio HF and DFT analysis of 4-nitrotoluene" by S. Ramalingam et al., Spectrochemica Acta A 75 (2010) 1308-1314.

    PubMed

    Tomkinson, John

    2010-10-01

    The title paper reports the ab initio calculated structure and vibrational spectra of 4-nitrotoluene. The calculated structure is wrong and the assignments are inconsistent with earlier work. We have recalculated the ab initio structure and reassigned the spectra in agreement with the standard text. PMID:20598628

  9. Comment on "Behavior of Re and Os during contact between an aqueous solution and oil: Consequences for the application of the Re-Os geochronometer to petroleum" [Geochim. Cosmochim. Acta 158 (2015) 1-21

    NASA Astrophysics Data System (ADS)

    Wu, Jia; Li, Zhen; Wang, Xuan-ce

    2016-08-01

    In a recent study, Mahdaoui et al. (2015) simulated the contact of oil with Re/Os-bearing aqueous fluids in petroleum reservoirs and concluded that both metals could be rapidly and substantially enriched in the oil fraction. These findings could have significant geological ramifications for the use of rhenium-osmium (Re-Os) geochronology in the age-dating of oil deposits. However, the lack of data reproducibility between parallel experiments and misused parameter of "recovery rate" has cast doubt on the main conclusions of the paper. Re-analyses of the raw data provided sufficient evidence to suggest that in petroleum basins with very low abundances of Re and Os, the extraction of these metals to oil is unlikely to be a geologically instantaneous process as the authors implied in their study. In addition, the possibility of reactor leakage in the contacting experiments cannot be completely ruled out.

  10. Corrigendum to ‘Evidence for shock heating and constraints on Martian surface temperatures revealed by 40Ar/39Ar thermochronometry of Martian meteorites’ [Geochim. Cosmochim. Acta (2010) 6900–6920

    DOE PAGES

    Cassata, William S.; Shuster, David L.; Renne, Paul R.; Weiss, Benjamin P.

    2014-10-23

    Here, the authors regret they have discovered errors in Eq. (3) and in a spreadsheet used to calculate cosmogenic exposure ages shown in Table 1. Eq. (3) is missing a term. The spreadsheet errors concerned an incorrect cell reference and application of Eq. (3). Correction of these errors results in ~15–20% changes to the exposure ages of all samples, minor (generally <0.2%) changes to the radioisotopic ages of some samples (those that entailed a correction for chlorine-derived 38Ar calculated based on the exposure age; see Section 3.3), and statistically insignificant changes to the inferred trapped components identified through isochron analyses.more » These modifications have no impact on the modeling, discussions, or conclusions in the paper, nor do the changes to radioisotopic ages exceed the 1 sigma uncertainties.« less

  11. Actas de la 4th mesa redonda sobre investigacion en "Lenguas Extranjeras" en la Universidad Autonoma Metropolitana 1996. (Proceedings from the 4th Roundtable on Investigation in Foreign Languages in the Autonomous Metropolitan University 1996).

    ERIC Educational Resources Information Center

    Zoreda, Margaret Lee, Comp.; Diop, Mamoudou Si, Comp.; Vivaldo Lima, Javier, Comp.

    The articles included in this volume were selected as exemplary papers from the conference in Mexico. The goal of the forum was to provide an opportunity for researchers from the three branches of the Universidad Autonoma Metropolitana (UAM) to meet and discuss research projects currently in progress at the university. The works presented here…

  12. Corrigendum to "Natural dye extract of lawsonia inermis seed as photo sensitizer for titanium dioxide based dye sensitized solar cells" [Spectrochim. Acta A Mol. Biomol. Spectrosc. 128 (2014) 420-426

    NASA Astrophysics Data System (ADS)

    Ananth, S.; Vivek, P.; Arumanayagam, T.; Murugakoothan, P.

    2015-05-01

    The authors regret to inform that the following text in page No. 425, "The conventionally prepared TiO2 based DSSC exhibits the observed values of Isc = 1.6 mA cm-2, Voc = 0.48 V and the calculated value of FF is 64.32%. Similarly, for pre dye treated TiO2 based DSSC, the observed values of Isc = 2.99 mA cm-2, Voc = 0.50 V and the calculated value of FF is 66.9%" should be read as, "The conventionally prepared TiO2 based DSSC exhibits the observed values of Isc = 2.99 mA cm-2, Voc = 0.50 V and the calculated value of FF is 66.9%. Similarly, for pre dye treated TiO2 based DSSC, the observed values of Isc = 4.2 mA cm-2, Voc = 0.56 V and the calculated value of FF is 62.5%". Though the text is typed wrongly, the I-V graph, the discussions and our conclusions are as same as that of our published article.

  13. Evolving possibilities: Post-embryonic axial elongation in salamanders with biphasic (Eurcyea cirrigera, E. longicauda, E. quadridigitata) and paedomorphic life cycles (Eurycea nana and Ambystoma mexicanum). Submitted Acta Zoologica

    PubMed Central

    Vaglia, Janet L.; White, Kurt; Case, Alison

    2014-01-01

    Typically the number of vertebrae an organism will have post-embryonically is determined during embryogenesis via the development of paired somites. Our research investigates the phenomenon of post-embryonic vertebral addition in salamander tails. We describe body and tail growth, and patterns of postsacral vertebral addition and elongation in context with caudal morphology for four plethodontids (Eurycea), and one ambystomatid. Eurycea nana and A. mexicanum have paedomorphic life cycles; E. cirrigera, E. longicauda and E. quadridigitata are biphasic. Specimens were collected, borrowed and/or purchased, and cleared and stained for bone and cartilage. Data collected include snout-vent length (SVL), tail length (TL), vertebral counts and centrum lengths. Eurycea species with biphasic life cycles had TLs that surpassed SVL following metamorphosis. Tails in paedomorphic species elongated but rarely exceeded body length. Larger TLs were associated with more vertebrae and longer vertebrae in all species. We observed that rates of postsacral vertebral addition varied little amongst species. Regional variation along the tail becomes prominent following metamorphosis in biphasic developers. In all species vertebrae in the posterior one-half of the tail taper towards the tip. We suggest a developmental link might exist between the ability to continually add vertebrae and regeneration in salamanders. PMID:24790225

  14. Corrigendum to "Isotopic and geochemical characterization of fossil brines of the Cambrian Mt. Simon sandstone and Ironton-Galesville formation from the Illinois Basin, USA" [Geochim. Cosmochim. Acta 165 (2015) 342-360

    NASA Astrophysics Data System (ADS)

    Labotka, Dana M.; Panno, Samuel V.; Locke, Randall A.; Freiburg, Jared T.

    2016-08-01

    The original Fig. 4 incorrectly represented data from Clayton et al. (1966). The deuterium values were reported in percent deuterium and mistaken by the authors as per mille. The corrected Fig. 4 Corrigendum is given and shows the data from Clayton et al. (1966) plotting in a similar manner as other published data for groundwater in the Illinois Basin. The data from Clayton et al. (1966) was not used in the discussion of the deep-seated Cambrian brines, and, therefore, this misrepresentation does not affect the conclusions of the original manuscript. The authors apologize for the oversight.

  15. Corrigendum to "Synthesis and spectral characterization of new homologous 1,3,5-triaryl-2-pyrazolines: Influence of alkyloxy chain length on fluorescence" [Spectrochim. Acta Part A: Mol. Biomol. Spectrosc. 133 (2014) 182-189

    NASA Astrophysics Data System (ADS)

    Abbas, Asghar; Hussain, Safdar; Hafeez, Noureen; Naseer, Muhammad Moazzam

    2015-03-01

    The authors regret to inform that the affiliation of one of the authors, namely, Noureen Hafeez has been written as Department of Forensic Medicine & Toxicology, Rawalpindi Institute of Health Sciences (RIHS), Bahria University, Islamabad, Pakistan in the published article. The correct address is shown above.

  16. Derechos Educacionales de los Padres: Una Explicacion de los Procedimientos de Seguridad para los Padres de Ninos con Discapacidades. Bajo la Clausula del Acta de Educacion para Individuos con Discapacidades (IDEA) y las Reglas para la Administracion del Acta de Educacion para Ninos Excepcionales (Educational Rights of Parents: An Explanation of Procedural Safeguards Available to Parents of Children with Disabilities. Under Provisions of the Individuals with Disabilities Education Act (IDEA) and the Rules for the Administration of the Exceptional Children's Educational Act [ECEA]).

    ERIC Educational Resources Information Center

    Mountain Plains Regional Resource Center, Des Moines, IA.

    This pamphlet, in Spanish, describes Colorado parents' educational rights under federal and state special education rules and regulations. It addresses: (1) free appropriate public education and termination of services; (2) required prior notice to parents if there is a proposed change or refusal to change a child's special education program; (3)…

  17. Crystal structure of azido­(η5-cyclo­penta­dien­yl)bis­(tri­phenyl­phosphane-κP)ruthenium(II) di­chloro­methane hemisolvate

    PubMed Central

    Hernández-Calva, Adriana; Meléndez-Balbuena, Lidia; Arroyo, Maribel; Ramírez-Monroy, Armando

    2014-01-01

    The title solvated complex, [Ru(η5-C5H5)(N3){P(C6H5)3}2]·0.5CH2Cl2, displays a typical piano-stool geometry about the RuII atom. The bond lengths and angles of the cyclo­penta­dienyl and phosphane ligands are very similar to that of the unsolvated complex [Taqui Khan et al. (1994 ▶). Acta Cryst. C50, 502–504]. The azide anion displays similar N—N distances of 1.173 (3) and 1.156 (3) Å and has an N—N—Ru angle of 119.20 (15)°, indicating a greater contribution of the canonical form Ru—N=N(+)=N(-) for the bonding situation. An intra­molecular C—H⋯N hydrogen-bonding inter­action between one ortho H atom of a phosphane ligand and the N atom coordinating to the metal is observed. A similar inter­molecular inter­action is observed between a meta H atom of a phosphane ligand and the terminal azide N atom of a neighbouring complex. Finally, two C—H⋯N inter­actions exists between the H atoms of the di­chloro­methane solvent mol­ecule and the terminal N atom of two azide anions. The solvent mol­ecule is located about a twofold rotation axis and shows disorder of the Cl atoms with an occupancy ratio of 0.62 (3):0.38 (3). PMID:25484673

  18. A second triclinic polymorph of azimsulfuron

    PubMed Central

    Kwon, Eunjin; Kim, Jineun; Park, Hyunjin; Kim, Tae Ho

    2016-01-01

    The title compound, C13H16N10O5S (systematic name: 1-(4,6-di­meth­oxypyrimidin-2-yl)-3-{[1-methyl-4-(2-methyl-2H-tetra­zol-5-yl)pyrazol-5-yl]sulfonyl}urea), is a second triclinic polymorph of this crystal [for the other, see: Jeon et al., (2015 ▸). Acta Cryst. E71, o470–o471]. There are two mol­ecules, A and B, in the asymmetric unit; the dihedral angles between the pyrazole ring and the tetra­zole and di­meth­oxy­pyrimidine ring planes are 72.84 (10) and 37.24 (14)°, respectively (mol­ecule A) and 84.38 (9) and 26.09 (15)°, respectively (mol­ecule B). Each mol­ecule features an intra­molecular N—H⋯N hydrogen bond. In the crystal, aromatic π–π stacking inter­actions [centroid–centroid separations = 3.9871 (16), 3.4487 (14) and 3.5455 (16) Å] link the mol­ecules into [001] chains. In addition, N—H⋯N, N—H⋯O, C—H⋯O and C—H⋯N hydrogen bonds occur, forming a three-dimensional architecture. We propose that the dimorphism results from differences in conformations and packing owing to different inter­molecular inter­actions, especially aromatic π–π stacking. PMID:27746943

  19. Crystal structure of azido-(η(5)-cyclo-penta-dien-yl)bis-(tri-phenyl-phosphane-κP)ruthenium(II) di-chloro-methane hemisolvate.

    PubMed

    Hernández-Calva, Adriana; Meléndez-Balbuena, Lidia; Arroyo, Maribel; Ramírez-Monroy, Armando

    2014-10-01

    The title solvated complex, [Ru(η(5)-C5H5)(N3){P(C6H5)3}2]·0.5CH2Cl2, displays a typical piano-stool geometry about the Ru(II) atom. The bond lengths and angles of the cyclo-penta-dienyl and phosphane ligands are very similar to that of the unsolvated complex [Taqui Khan et al. (1994 ▶). Acta Cryst. C50, 502-504]. The azide anion displays similar N-N distances of 1.173 (3) and 1.156 (3) Å and has an N-N-Ru angle of 119.20 (15)°, indicating a greater contribution of the canonical form Ru-N=N((+))=N((-)) for the bonding situation. An intra-molecular C-H⋯N hydrogen-bonding inter-action between one ortho H atom of a phosphane ligand and the N atom coordinating to the metal is observed. A similar inter-molecular inter-action is observed between a meta H atom of a phosphane ligand and the terminal azide N atom of a neighbouring complex. Finally, two C-H⋯N inter-actions exists between the H atoms of the di-chloro-methane solvent mol-ecule and the terminal N atom of two azide anions. The solvent mol-ecule is located about a twofold rotation axis and shows disorder of the Cl atoms with an occupancy ratio of 0.62 (3):0.38 (3). PMID:25484673

  20. Ir-Spectroscopy of Glycine and its Complexes with Water in Helium Nanodroplets

    NASA Astrophysics Data System (ADS)

    Letzner, M.; Grün, S. A.; Schwaab, G.; Havenith, M.

    2011-06-01

    Glycine is the smallest amino acid, and therefore it is of special interest as a model and starting point for theoretical and experimental studies. Whereas the crystalline form of glycine consists of zwitterions NH_3+-CH_2-COO-, gas phase glycine is known to exist in the nonionized form NH_2-CH_2-COOH. The interaction between glycine and water has been widely studied using a large variety of theoretical methods. Depending on the theoretical level used, a stabilisation of the zwitterionic form is predicted for complexes containing from 2 to 7 water molecules. In low-temperature Ar matrices a set of characteristic IR absorption bands for the zwitterionic form has been observed. The higher stoichiometry complexes (glycine)\\cdots(H_2O)_n with n larger than 3 are demonstrated to be zwitterionic H-bonded complexes. The multitude of conformations expected for these glycine-water complexes makes a combination of low temperature and high resolution spectroscopy essential. We want to use the advantages of our experiment to investigate glycine and its complexes with water in helium-nanodroplets at ultracold temperatures in the range from 3000-3800 Cm-1. Our measurements were carried out using a high power IR-OPO (cw: 2.7 W) as radiation source and a helium nanodroplet spectrometer. Helium-nanodroplets are formed by expansion of helium at 55 bar through a 5 μm nozzle which is kept at a temperature of 16 K. The status of the project is presented. P.-G. Jönsson et al., Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 28, 1827 (1972) G. Junk et al., J. Am. Chem. Soc. 85, 839 (1963) R. Ramaekers et al., J. Chem. Phys., 120 (2004)

  1. Icosahedral symmetry breaking: C(60) to C(84), C(108) and to related nanotubes.

    PubMed

    Bodner, Mark; Bourret, Emmanuel; Patera, Jiri; Szajewska, Marzena

    2015-05-01

    This paper completes the series of three independent articles [Bodner et al. (2013). Acta Cryst. A69, 583-591, (2014), PLOS ONE, 10.1371/journal.pone.0084079] describing the breaking of icosahedral symmetry to subgroups generated by reflections in three-dimensional Euclidean space {\\bb R}^3 as a mechanism of generating higher fullerenes from C60. The icosahedral symmetry of C60 can be seen as the junction of 17 orbits of a symmetric subgroup of order 4 of the icosahedral group of order 120. This subgroup is noted by A1 × A1, because it is isomorphic to the Weyl group of the semi-simple Lie algebra A1 × A1. Thirteen of the A1 × A1 orbits are rectangles and four are line segments. The orbits form a stack of parallel layers centered on the axis of C60 passing through the centers of two opposite edges between two hexagons on the surface of C60. These two edges are the only two line segment layers to appear on the surface shell. Among the 24 convex polytopes with shell formed by hexagons and 12 pentagons, having 84 vertices [Fowler & Manolopoulos (1992). Nature (London), 355, 428-430; Fowler & Manolopoulos (2007). An Atlas of Fullerenes. Dover Publications Inc.; Zhang et al. (1993). J. Chem. Phys. 98, 3095-3102], there are only two that can be identified with breaking of the H3 symmetry to A1 × A1. The remaining ones are just convex shells formed by regular hexagons and 12 pentagons without the involvement of the icosahedral symmetry.

  2. Crystal structures of spinel-type Na2MoO4 and Na2WO4 revisited using neutron powder diffraction.

    PubMed

    Fortes, A Dominic

    2015-06-01

    Time-of-flight neutron powder diffraction data have been collected from Na2MoO4 and Na2WO4 to a resolution of sin (θ)/λ = 1.25 Å(-1), which is substanti-ally better than the previous analyses using Mo Kα X-rays, providing roughly triple the number of measured reflections with respect to the previous studies [Okada et al. (1974 ▶). Acta Cryst. B30, 1872-1873; Bramnik & Ehrenberg (2004 ▶). Z. Anorg. Allg. Chem. 630, 1336-1341]. The unit-cell parameters are in excellent agreement with literature data [Swanson et al. (1962 ▶). NBS Monograph No. 25, sect. 1, pp. 46-47] and the structural parameters for the molybdate agree very well with those of Bramnik & Ehrenberg (2004 ▶). However, the tungstate structure refinement of Okada et al. (1974 ▶) stands apart as being conspicuously inaccurate, giving significantly longer W-O distances, 1.819 (8) Å, and shorter Na-O distances, 2.378 (8) Å, than are reported here or in other simple tungstates. As such, this work represents an order-of-magnitude improvement in precision for sodium molybdate and an equally substantial improvement in both accuracy and precision for sodium tungstate. Both compounds adopt the spinel structure type. The Na(+) ions have site symmetry .-3m and are in octa-hedral coordination while the transition metal atoms have site symmetry -43m and are in tetra-hedral coordination.

  3. Anharmonicity and isomorphic phase transition: a multi-temperature X-ray single-crystal and powder diffraction study of 1-(2′-aminophenyl)-2-methyl-4-nitroimidazole

    PubMed Central

    Poulain, Agnieszka; Wenger, Emmanuel; Durand, Pierrick; Jarzembska, Katarzyna N.; Kamiński, Radosław; Fertey, Pierre; Kubicki, Maciej; Lecomte, Claude

    2014-01-01

    The harmonic model of atomic nuclear motions is usually enough for multipole modelling of high-resolution X-ray diffraction data; however, in some molecular crystals, such as 1-(2′-aminophenyl)-2-methyl-4-nitro-1H-imidazole [Paul, Kubicki, Jelsch et al. (2011 ▶). Acta Cryst. B67, 365–378], it may not be sufficient for a correct description of the charge-density distribution. Multipole refinement using harmonic atom vibrations does not lead to the best electron density model in this case and the so-called ‘shashlik-like’ pattern of positive and negative residual electron density peaks is observed in the vicinity of some atoms. This slight disorder, which cannot be modelled by split atoms, was solved using third-order anharmonic nuclear motion (ANM) parameters. Multipole refinement of the experimental high-resolution X-ray diffraction data of 1-(2′-aminophenyl)-2-methyl-4-nitro-1H-imidazole at three different temperatures (10, 35 and 70 K) and a series of powder diffraction experiments (20 ≤ T ≤ 300 K) were performed to relate this anharmonicity observed for several light atoms (N atoms of amino and nitro groups, and O atoms of nitro groups) to an isomorphic phase transition reflected by a change in the b cell parameter around 65 K. The observed disorder may result from the coexistence of domains of two phases over a large temperature range, as shown by low-temperature powder diffraction. PMID:25075327

  4. Compounds with a ‘stuffed’ anti-bixbyite-type structure, analysed in terms of the Zintl–Klemm and coordination-defect concepts

    PubMed Central

    Vegas, Angel; Martin, Raymond L.; Bevan, D. J. M.

    2009-01-01

    The bixbyite structure (Mn2O3) () is often described as a distorted face-centered cubic (f.c.c.) array of Mn atoms, with O atoms occupying 3/4 of the tetrahedral holes. The empty M 4 tetrahedra are centred at 16c. In anti-bixbyite structures (Mg3N2), cation vacancies are centred in empty N4 tetrahedra. If 16 hypothetical atoms were located at this site they would form the structure of γ-Si. This means that anti-bixbyite structures are ideally prepared to accommodate Si(Ge) atoms at these holes. Several compounds (Li3AlN2 and Li3ScN2) fully satisfy this expectation. They are really anti-bixbyites ‘stuffed’ with Al(Sc). The presence of these atoms in 16c is illuminated in the light of the extended Zintl–Klemm concept (EZKC) [Vegas & García-Baonza (2007 ▶). Acta Cryst. B63, 339–345], from which a compound would be the result of ‘multiple resonance’ pseudo-structures, emerging from electron transfers between any species pair (like or unlike atoms, cations or anions). The coordination-defect (CD) concept [Bevan & Martin (2008) ▶. J. Solid State Chem. 181, 2250–2259] is also consistent with the EZKC description of the pseudo-structures. A more profound insight into crystal structures is gained if one is not restricted to the contemplation of classical anions and cations in their conventional oxidation states. PMID:19155554

  5. Distinguishing tautomerism in the crystal structure of (Z)-N-(5-ethyl-2,3-di-hydro-1,3,4-thiadiazol-2-ylidene) -4-methylbenzenesulfonamide using DFT-D calculations and {sup 13}C solid-state NMR

    SciTech Connect

    Li, Xiaozhou; Bond, Andrew D.; Johansson, Kristoffer E.; Van de Streek, Jacco

    2014-08-01

    The crystal structure of (Z)-N-(5-ethyl-2,3-di-hydro-1,3,4-thiadiazol-2-ylidene) -4-methylbenzenesulfonamide contains an imine tautomer, rather than the previously reported amine tautomer. The tautomers can be distinguished using dispersion-corrected density functional theory calculations and by comparison of calculated and measured {sup 13}C solid-state NMR spectra. The crystal structure of the title compound, C{sub 11}H{sub 13}N{sub 3}O{sub 2}S{sub 2}, has been determined previously on the basis of refinement against laboratory powder X-ray diffraction (PXRD) data, supported by comparison of measured and calculated {sup 13}C solid-state NMR spectra [Hangan et al. (2010 ▶). Acta Cryst. B66, 615–621]. The mol@@ecule is tautomeric, and was reported as an amine tautomer [systematic name: N-(5-ethyl-1,3,4-thia@@diazol-2-yl)-p-toluene@@sulfonamide], rather than the correct imine tautomer. The protonation site on the mol@@ecule’s 1,3,4-thia@@diazole ring is indicated by the inter@@molecular contacts in the crystal structure: N—H⋯O hydrogen bonds are established at the correct site, while the alternative protonation site does not establish any notable inter molecular inter@@actions. The two tautomers provide essentially identical Rietveld fits to laboratory PXRD data, and therefore they cannot be directly distinguished in this way. However, the correct tautomer can be distinguished from the incorrect one by previously reported qu@@anti@@tative criteria based on the extent of structural distortion on optimization of the crystal structure using dispersion-corrected density functional theory (DFT-D) calculations. Calculation of the {sup 13}C SS-NMR spectrum based on the correct imine tautomer also provides considerably better agreement with the measured {sup 13}C SS-NMR spectrum.

  6. Crystal structure of tetra-kis-[μ2-2-(di-methyl-amino)-ethano-lato-κ(3) N,O:O]di-μ3-hydroxido-di-thio-cyanato-κ(2) N-dichromium(III)dilead(II) di-thio-cyanate aceto-nitrile monosolvate.

    PubMed

    Rusanova, Julia A; Semenaka, Valentyna V; Omelchenko, Irina V

    2016-04-01

    The tetra-nuclear complex cation of the title compound, [Cr2Pb2(NCS)2(OH)2(C4H10NO)4](SCN)2·CH3CN, lies on an inversion centre. The main structural feature of the cation is a distorted seco-norcubane Pb2Cr2O6 cage with a central four-membered Cr2O2 ring. The Cr(III) ion is coordinated in a distorted octa-hedron, which involves two N atoms of one bidentate ligand and one thio-cyanate anion, two μ2-O atoms of 2-(di-methyl-amino)-ethano-late ligands and two μ3-O atoms of hydroxide ions. The coordination geometry of the Pb(II) ion is a distorted disphenoid, which involves one N atom, two μ2-O atoms and one μ3-O atom. In addition, weak Pb⋯S inter-actions involving the coordinating and non-coordinating thio-cyanate anions are observed. In the crystal, the complex cations are linked through the thio-cyanate anions via the Pb⋯S inter-actions and O-H⋯N hydrogen bonds into chains along the c axis. The chains are further linked together via S⋯S contacts. The contribution of the disordered solvent aceto-nitrile mol-ecule was removed with the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] procedure in PLATON. The solvent is included in the reported mol-ecular formula, weight and density.

  7. Crystal structure of an unknown solvate of (piperazine-κN){5,10,15,20-tetra-kis-[4-(benzo-yloxy)phen-yl]porphyrinato-κ(4) N}zinc.

    PubMed

    Nasri, Soumaya; Ezzayani, Khaireddine; Turowska-Tyrk, Ilona; Roisnel, Thierry; Nasri, Habib

    2016-07-01

    The title compound, [Zn(C72H44N4O8)(C4H10N2)] or [Zn(TPBP)(pipz] (where TPBP and pipz are 5,10,15,20-tetra-kis-[4-(benzo-yloxy)phen-yl]porphyrinato and piperazine ligands respectively), features a distorted square-pyramidal coordin-ation geometry about the central Zn(II) atom. This central atom is chelated by the four N atoms of the porphyrinate anion and further coordinated by a nitro-gen atom of the piperazine axial ligand, which adopts a chair confirmation. The average Zn-N(pyrrole) bond length is 2.078 (7) Å and the Zn- N(pipz) bond length is 2.1274 (19) Å. The zinc cation is displaced by 0.4365 (4) Å from the N4C20 mean plane of the porphyrinate anion toward the piperazine axial ligand. This porphyrinate macrocycle exhibits major saddle and moderate ruffling deformations. In the crystal, the supra-molecular structure is made by parallel pairs of layers along (100), with an inter-layer distance of 4.100 Å while the distance between two pairs of layers is 4.047 Å. A region of electron density was treated with the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] procedure in PLATON following unsuccessful attempts to model it as being part of disordered n-hexane solvent and water mol-ecules. The given chemical formula and other crystal data do not take into account these solvent mol-ecules.

  8. Redetermined structure of gossypol (P3 polymorph).

    PubMed

    Honkeldieva, Muhabbat; Kunafiev, Rishad; Hamidov, Hayrullo I

    2015-07-01

    An improved crystal structure of the title compound, C30H30O8 (systematic name: 1,1',6,6',7,7'-hexa-hydroxy-5,5'-diisopropyl-3,3'-dimeth-yl[2,2'-bi-naphthalene]-8,8'-dicarbaldehyde), was determined based on modern CCD data. Compared to the previous structure [Talipov et al. (1985). Khim. Prirod. Soedin. (Chem. Nat. Prod.), 6, 20-24], geometrical precision has been improved (typical C-C bond-distance s.u. = 0.002 Å in the present structure compared to 0.005 Å in the previous structure) and the locations of several H atoms have been corrected. The gossypol mol-ecules are in the aldehyde tautomeric form and the dihedral angle between the naphthyl fragments is 80.42 (4)°. Four intra-molecular O-H⋯O hydrogen bonds are formed. In the crystal, inversion dimers with graph-set motif R 2 (2)(20) are formed by pairs of O-H⋯O hydrogen bonds; another pair of O-H⋯O hydrogen bonds with the same graph-set motif links the dimers into [001] chains. The packing of such chains in the crystal leads to the formation of channels (diameter = 5-8 Å) propagating in the [101] direction. The channels presumably contain highly disordered solvent mol-ecules; their contribution to the scattering was removed with the SQUEEZE [Spek (2015). Acta Cryst. C71, 9-18] routine in PLATON and the stated mol-ecular mass, density etc., do not take them into account.

  9. Improving experimental phases for strong reflections prior to density modification

    SciTech Connect

    Uervirojnangkoorn, Monarin; Hilgenfeld, Rolf; Terwilliger, Thomas C.; Read, Randy J.

    2013-10-01

    A genetic algorithm has been developed to optimize the phases of the strongest reflections in SIR/SAD data. This is shown to facilitate density modification and model building in several test cases. Experimental phasing of diffraction data from macromolecular crystals involves deriving phase probability distributions. These distributions are often bimodal, making their weighted average, the centroid phase, improbable, so that electron-density maps computed using centroid phases are often non-interpretable. Density modification brings in information about the characteristics of electron density in protein crystals. In successful cases, this allows a choice between the modes in the phase probability distributions, and the maps can cross the borderline between non-interpretable and interpretable. Based on the suggestions by Vekhter [Vekhter (2005 ▶), Acta Cryst. D61, 899–902], the impact of identifying optimized phases for a small number of strong reflections prior to the density-modification process was investigated while using the centroid phase as a starting point for the remaining reflections. A genetic algorithm was developed that optimizes the quality of such phases using the skewness of the density map as a target function. Phases optimized in this way are then used in density modification. In most of the tests, the resulting maps were of higher quality than maps generated from the original centroid phases. In one of the test cases, the new method sufficiently improved a marginal set of experimental SAD phases to enable successful map interpretation. A computer program, SISA, has been developed to apply this method for phase improvement in macromolecular crystallography.

  10. X-ray structure of the metcyano form of dehaloperoxidase from Amphitrite ornata: evidence for photoreductive dissociation of the iron-cyanide bond

    SciTech Connect

    de Serrano, V.S.; Davis, M.F.; Gaff, J.F.; Zhang, Q.; Chen, Z.; D'Antonio, E.L.; Bowden, E.F.; Rose, R.; Franzen, S.

    2010-11-09

    X-ray crystal structures of the metcyano form of dehaloperoxidase-hemoglobin (DHP A) from Amphitrite ornata (DHPCN) and the C73S mutant of DHP A (C73SCN) were determined using synchrotron radiation in order to further investigate the geometry of diatomic ligands coordinated to the heme iron. The DHPCN structure was also determined using a rotating-anode source. The structures show evidence of photoreduction of the iron accompanied by dissociation of bound cyanide ion (CN{sup -}) that depend on the intensity of the X-ray radiation and the exposure time. The electron density is consistent with diatomic molecules located in two sites in the distal pocket of DHPCN. However, the identities of the diatomic ligands at these two sites are not uniquely determined by the electron-density map. Consequently, density functional theory calculations were conducted in order to determine whether the bond lengths, angles and dissociation energies are consistent with bound CN{sup -} or O{sub 2} in the iron-bound site. In addition, molecular-dynamics simulations were carried out in order to determine whether the dynamics are consistent with trapped CN{sup -} or O{sub 2} in the second site of the distal pocket. Based on these calculations and comparison with a previously determined X-ray crystal structure of the C73S-O{sub 2} form of DHP [de Serrano et al. (2007), Acta Cryst. D63, 1094-1101], it is concluded that CN{sup -} is gradually replaced by O{sub 2} as crystalline DHP is photoreduced at 100 K. The ease of photoreduction of DHP A is consistent with the reduction potential, but suggests an alternative activation mechanism for DHP A compared with other peroxidases, which typically have reduction potentials that are 0.5 V more negative. The lability of CN{sup -} at 100 K suggests that the distal pocket of DHP A has greater flexibility than most other hemoglobins.

  11. Ring-strain release in neutral and dicationic 7,8,17,18-tetra­bromo-5,10,15,20-tetra­phenyl­porphyrin: crystal structures of C44H26Br4N4 and C44H28Br4N4 2+·2ClO4 −·3CH2Cl2

    PubMed Central

    Scheidt, W. Robert; Duval, Hugues F.; Oliver, Allen G.

    2016-01-01

    Two porphyrin complexes were studied to determine the effects of protonation on ring deformation within the porphyrin. The porphyrin 7,8,17,18-tetra­bromo-5,10,15,20-tetra­phenyl­porphyrin, C44H26Br4N4, was selected because the neutral species is readily doubly protonated to yield a dication, which was crystallized here with perchlorate counter-ions as a di­chloro­methane tris­olvate, C44H28Br4N4 2+·2ClO4 −·3CH2Cl2. The centrosymmetric neutral species is observed to have a mild ‘ruffling’ of the pyrrole rings and is essentially planar throughout; intra­molecular N—H⋯N hydrogen bonds occur. In contrast, the dication exhibits considerable deformation, with the pyrrole rings oriented well out of the plane of the porphyrin, resulting in a ‘saddle’ conformation of the ring. The charged species forms N—H⋯O hydrogen bonds to the perchlorate anions, which lie above and below the plane of the porphyrin ring. Distortions to the planarity of the pyrrole rings in both cases are very minor. The characterization of the neutral species represents a low-temperature redetermination of the previous room-temperature analyses [Zou et al. (1995 ▸). Acta Cryst. C51, 760–761; Rayati et al. (2008 ▸). Polyhedron, pp. 2285–2290], which showed disorder and physically unrealistic displacement parameters. PMID:27308051

  12. Crystal structure of an unknown solvate of (piperazine-κN){5,10,15,20-tetra­kis­[4-(benzo­yloxy)phen­yl]porphyrinato-κ4 N}zinc

    PubMed Central

    Nasri, Soumaya; Ezzayani, Khaireddine; Turowska-Tyrk, Ilona; Roisnel, Thierry; Nasri, Habib

    2016-01-01

    The title compound, [Zn(C72H44N4O8)(C4H10N2)] or [Zn(TPBP)(pipz] (where TPBP and pipz are 5,10,15,20-tetra­kis­[4-(benzo­yloxy)phen­yl]porphyrinato and piperazine ligands respectively), features a distorted square-pyramidal coordin­ation geometry about the central ZnII atom. This central atom is chelated by the four N atoms of the porphyrinate anion and further coordinated by a nitro­gen atom of the piperazine axial ligand, which adopts a chair confirmation. The average Zn—N(pyrrole) bond length is 2.078 (7) Å and the Zn— N(pipz) bond length is 2.1274 (19) Å. The zinc cation is displaced by 0.4365 (4) Å from the N4C20 mean plane of the porphyrinate anion toward the piperazine axial ligand. This porphyrinate macrocycle exhibits major saddle and moderate ruffling deformations. In the crystal, the supra­molecular structure is made by parallel pairs of layers along (100), with an inter­layer distance of 4.100 Å while the distance between two pairs of layers is 4.047 Å. A region of electron density was treated with the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9–18] procedure in PLATON following unsuccessful attempts to model it as being part of disordered n-hexane solvent and water mol­ecules. The given chemical formula and other crystal data do not take into account these solvent mol­ecules. PMID:27555935

  13. Redetermined structure of gossypol (P3 polymorph).

    PubMed

    Honkeldieva, Muhabbat; Kunafiev, Rishad; Hamidov, Hayrullo I

    2015-07-01

    An improved crystal structure of the title compound, C30H30O8 (systematic name: 1,1',6,6',7,7'-hexa-hydroxy-5,5'-diisopropyl-3,3'-dimeth-yl[2,2'-bi-naphthalene]-8,8'-dicarbaldehyde), was determined based on modern CCD data. Compared to the previous structure [Talipov et al. (1985). Khim. Prirod. Soedin. (Chem. Nat. Prod.), 6, 20-24], geometrical precision has been improved (typical C-C bond-distance s.u. = 0.002 Å in the present structure compared to 0.005 Å in the previous structure) and the locations of several H atoms have been corrected. The gossypol mol-ecules are in the aldehyde tautomeric form and the dihedral angle between the naphthyl fragments is 80.42 (4)°. Four intra-molecular O-H⋯O hydrogen bonds are formed. In the crystal, inversion dimers with graph-set motif R 2 (2)(20) are formed by pairs of O-H⋯O hydrogen bonds; another pair of O-H⋯O hydrogen bonds with the same graph-set motif links the dimers into [001] chains. The packing of such chains in the crystal leads to the formation of channels (diameter = 5-8 Å) propagating in the [101] direction. The channels presumably contain highly disordered solvent mol-ecules; their contribution to the scattering was removed with the SQUEEZE [Spek (2015). Acta Cryst. C71, 9-18] routine in PLATON and the stated mol-ecular mass, density etc., do not take them into account. PMID:26279897

  14. Crystal structure of an unknown solvate of (piperazine-κN){5,10,15,20-tetra-kis-[4-(benzo-yloxy)phen-yl]porphyrinato-κ(4) N}zinc.

    PubMed

    Nasri, Soumaya; Ezzayani, Khaireddine; Turowska-Tyrk, Ilona; Roisnel, Thierry; Nasri, Habib

    2016-07-01

    The title compound, [Zn(C72H44N4O8)(C4H10N2)] or [Zn(TPBP)(pipz] (where TPBP and pipz are 5,10,15,20-tetra-kis-[4-(benzo-yloxy)phen-yl]porphyrinato and piperazine ligands respectively), features a distorted square-pyramidal coordin-ation geometry about the central Zn(II) atom. This central atom is chelated by the four N atoms of the porphyrinate anion and further coordinated by a nitro-gen atom of the piperazine axial ligand, which adopts a chair confirmation. The average Zn-N(pyrrole) bond length is 2.078 (7) Å and the Zn- N(pipz) bond length is 2.1274 (19) Å. The zinc cation is displaced by 0.4365 (4) Å from the N4C20 mean plane of the porphyrinate anion toward the piperazine axial ligand. This porphyrinate macrocycle exhibits major saddle and moderate ruffling deformations. In the crystal, the supra-molecular structure is made by parallel pairs of layers along (100), with an inter-layer distance of 4.100 Å while the distance between two pairs of layers is 4.047 Å. A region of electron density was treated with the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] procedure in PLATON following unsuccessful attempts to model it as being part of disordered n-hexane solvent and water mol-ecules. The given chemical formula and other crystal data do not take into account these solvent mol-ecules. PMID:27555935

  15. Crystal structure of a new monoclinic polymorph of 2,4-di­hydroxy­benzaldehyde 4-methyl­thio­semi­carbazone

    PubMed Central

    Salam, M. A.; Hussein, Mouayed A.; Tiekink, Edward R. T.

    2015-01-01

    The title compound, C9H11N3O2S, is a second monoclinic (P21/c) polymorph of the previously reported Cc form [Tan et al. (2008b ▸). Acta Cryst. E64, o2224]. The mol­ecule is non-planar, with the dihedral angle between the N3CS residue (r.m.s. deviation = 0.0816 Å) and the benzene ring being 21.36 (4)°. The conformation about the C=N bond [1.292 (2) Å] is E, the two N-bound H atoms are anti, and the inner hy­droxy O-bound and outer amide N-bound H atoms form intra­molecular hydrogen bonds to the imine N atom. Crucially, the H atom of the outer hy­droxy group is approximately syn to the H atom of the benzene C atom connecting the two C atoms bearing the hy­droxy substituents. This arrangement enables the formation of supra­molecular tubes aligned along [010] and sustained by N—H⋯O, O—H⋯S and N—H⋯S hydrogen bonds; the tubes pack with no specific inter­actions between them. While the mol­ecular structure in the Cc form is comparable, the H atom of the outer hy­droxy group is approximately anti, rather than syn. This different orientation leads to the formation a three-dimensional architecture based on N—H⋯O and O—H⋯S hydrogen bonds. PMID:25705451

  16. Crystal structure of tetra-kis-[μ2-2-(di-methyl-amino)-ethano-lato-κ(3) N,O:O]di-μ3-hydroxido-di-thio-cyanato-κ(2) N-dichromium(III)dilead(II) di-thio-cyanate aceto-nitrile monosolvate.

    PubMed

    Rusanova, Julia A; Semenaka, Valentyna V; Omelchenko, Irina V

    2016-04-01

    The tetra-nuclear complex cation of the title compound, [Cr2Pb2(NCS)2(OH)2(C4H10NO)4](SCN)2·CH3CN, lies on an inversion centre. The main structural feature of the cation is a distorted seco-norcubane Pb2Cr2O6 cage with a central four-membered Cr2O2 ring. The Cr(III) ion is coordinated in a distorted octa-hedron, which involves two N atoms of one bidentate ligand and one thio-cyanate anion, two μ2-O atoms of 2-(di-methyl-amino)-ethano-late ligands and two μ3-O atoms of hydroxide ions. The coordination geometry of the Pb(II) ion is a distorted disphenoid, which involves one N atom, two μ2-O atoms and one μ3-O atom. In addition, weak Pb⋯S inter-actions involving the coordinating and non-coordinating thio-cyanate anions are observed. In the crystal, the complex cations are linked through the thio-cyanate anions via the Pb⋯S inter-actions and O-H⋯N hydrogen bonds into chains along the c axis. The chains are further linked together via S⋯S contacts. The contribution of the disordered solvent aceto-nitrile mol-ecule was removed with the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] procedure in PLATON. The solvent is included in the reported mol-ecular formula, weight and density. PMID:27375871

  17. Structural similarities in tetraaryltins described by virtual non-crystallographic rotations or translations: Kitaigorodskii's morphotropism is revisited.

    PubMed

    Kálmán, Alajos; Fábián, László

    2007-06-01

    Recently Kálmán [(2005), Acta Cryst. B61, 536-547] revealed that semirigid molecules or their patterns held together e.g. by hydrogen bonds may perform non-crystallographic rotations (through 180, 90 degrees etc.) around themselves whenever a substitution, ring enlargement or isomerization destroys the existing close packing, i.e. the novel substituent or the enlarged ring can no longer fit in the hollows formed between the molecules. In other words, the old and new arrangements of such chemically similar molecules can be converted into each other by virtual rotations. However, when a semirigid molecule without substitution, but under the influence of solvents, temperature etc., is fully or partly rearranged in the solid state, the corresponding non-crystallographic rotation (hereinafter ncr) is real and gives rise to polymorphism. Such polymorphs are hallmarked by full or partial isostructurality and show that ncrs always occur together with isostructurality. First Kitaigorodskii [(1961), Organic Chemical Crystallography, New York: Consultants Bureau] reported on the structural similarity of three tetraaryltins, (p-RC(6)H(4))(4)Sn, R = H, CH(3), CH(3)O, which is terminated by the larger C(2)H(5)O group. A revisit to these structures revealed that the tetragonal --> monoclinic conversion termed by Kitaigorodskii as a ;morphotropic step' is also performed by an ncr. Similarly, other tetraaryltins in the literature are related by ncrs or the nc translation of the semirigid tetrahedra, or they remain isostructural. Since one of the definitions of morphotropism, a word of Greek origin, is 'turn of form', the ncrs of semirigid molecules can be denoted--following Kitaigorodskii--by this word, whereas its alternative definition in the morphological crystallography of ;unidirectional changes' [applied by Groth (1870). Ber. Chem. Ges. 3, 449-457] covers the non-crystallographic translations described first in this work.

  18. Image-plate synchrotron laue data collection and subsequent structural analysis of a small test crystal of a nickel-containing aluminophosphate.

    PubMed

    Snell, E; Habash, J; Helliwell, M; Helliwell, J R; Raftery, J; Kaucic, V; Campbell, J W

    1995-01-01

    Image plates have advantages over photographic films, which include wider dynamic range, higher detector quantum efficiency, reduced exposure time and large size. In this study, an on-line image-plate system has been used to record crystallographic data from a small crystal. In particular, synchrotron Laue data were recorded with lambda(min) = 0.455, lambda(max) = 1.180 A, in 20 images 10 degrees apart and with an exposure time of 0.3 s each from a crystal (0.02 x 0.05 x 0.25 mm) of a nickel-containing aluminophosphate, NiAPO. The Laue data were analyzed with the Daresbury Laue software, including the application of an absorption correction. The structure was solved by a combination of the Patterson method and successive difference Fourier calculations using SHELXS86 and SHELXL93; the final R value for 1934 unique reflections (all data) and 310 parameters was 7.90%. The structure agrees with that determined by monochromatic diffractometry using the same crystal and reported by Helliwell, Gallois, Kariuki, Kaucic & Helliwell [Acta Cryst. (1993), B49, 420-428] with an r.m.s. deviation of 0.03 A. Hence, this study shows the image-plate device to be very effective for synchrotron data collection and subsequent structure analysis from small crystals, i.e. 0.02 x 0.05 x 0.25 mm, in chemical crystallography as well as providing further confirmation of the practicability of Laue data in structure solution and refinement. PMID:16714782

  19. Etude structurale et vibrationnelle d’un nouveau composé complexe de cobalt: [Co(imidazole)4Cl]Cl

    PubMed Central

    Derbel, Amira; Mhiri, Tahar; Graia, Mohsen

    2015-01-01

    In the title complex, chlorido­tetra­kis­(1H-imidazole-κN 3)cobalt(II) chloride, [CoCl(C3H4N2)4]Cl, the CoII cation has a distorted square-pyramidal coordination environment. It is coordinated by four N atoms of four imidazole (Im) groups in the basal plane, and by a Cl atom in the apical position. It is isostructural with [Cu(Im)4Cl]Cl [Morzyk-Ociepa et al. (2012 ▸). J. Mol. Struct. 1028, 49–56] and [Cu(Im)4Br]Br [Hossaini Sadr et al. (2004 ▸). Acta Cryst. E60, m1324–m1326]. In the crystal, the [CoCl(C3H4N2)4]+ cations and Cl− anions are linked via N—H⋯Cl hydrogen bonds, forming layers parallel to (010). These layers are linked via C—H⋯Cl hydrogen bonds and C—H⋯π and π–π [inter-centroid distance = 3.794 (2) Å] inter­actions, forming a three-dimensional framework. The IR spectrum shows vibrational bands typical for imidazol groups. The monoclinic unit cell of the title compound emulates an ortho­rhom­bic cell as its β angle is close to 90°. The crystal is twinned, with the refined ratio of twin components being 0.569 (1):0.431 (1). PMID:26594402

  20. High- and low-temperature phases in isostructural 4-chloro-3-nitroaniline and 4-iodo-3-nitroaniline.

    PubMed

    Fábry, Jan; Dušek, Michal; Vaněk, Přemysl; Rafalovskyi, Iegor; Hlinka, Jiří; Urban, Jiří

    2014-12-01

    The structures of 4-chloro-3-nitroaniline, C6H5ClN2O2, (I), and 4-iodo-3-nitroaniline, C6H5IN2O2, (II), are isomorphs and both undergo continuous (second order) phase transitions at 237 and 200 K, respectively. The structures, as well as their phase transitions, have been studied by single-crystal X-ray diffraction, Raman spectroscopy and difference scanning calorimetry experiments. Both high-temperature phases (293 K) show disorder of the nitro substituents, which are inclined towards the benzene-ring planes at two different orientations. In the low-temperature phases (120 K), both inclination angles are well maintained, while the disorder is removed. Concomitantly, the b axis doubles with respect to the room-temperature cell. Each of the low-temperature phases of (I) and (II) contains two pairs of independent molecules, where the molecules in each pair are related by noncrystallographic inversion centres. The molecules within each pair have the same absolute value of the inclination angle. The Flack parameter of the low-temperature phases is very close to 0.5, indicating inversion twinning. This can be envisaged as stacking faults in the low-temperature phases. It seems that competition between the primary amine-nitro N-H···O hydrogen bonds which form three-centred hydrogen bonds is the reason for the disorder of the nitro groups, as well as for the phase transition in both (I) and (II). The backbones of the structures are formed by N-H···N hydrogen bonding of moderate strength which results in the graph-set motif C(3). This graph-set motif forms a zigzag chain parallel to the monoclinic b axis and is maintained in both the high- and the low-temperature structures. The primary amine groups are pyramidal, with similar geometric values in all four determinations. The high-temperature phase of (II) has been described previously [Garden et al. (2004). Acta Cryst. C60, o328-o330].

  1. Three new [XC(O)NH]P(O)[N(CH2C6H5)2]2 phosphoric triamides (X = CClF2, 3-F-C6H4 and 3,5-F2-C6H3): a database analysis of tertiary N-atom geometry in compounds with a C(O)NHP(O)[N]2 core.

    PubMed

    Pourayoubi, Mehrdad; Jasinski, Jerry P; Shoghpour Bayraq, Samad; Eshghi, Hossein; Keeley, Amanda C; Bruno, Giuseppe; Amiri Rudbari, Hadi

    2012-10-01

    In the phosphoric triamides N,N,N',N'-tetrabenzyl-N''-(2-chloro-2,2-difluoroacetyl)phosphoric triamide, C(30)H(29)ClF(2)N(3)O(2)P, (I), N,N,N',N'-tetrabenzyl-N''-(3-fluorobenzoyl)phosphoric triamide, C(35)H(33)FN(3)O(2)P, (II), and N,N,N',N'-tetrabenzyl-N''-(3,5-difluorobenzoyl)phosphoric triamide, C(35)H(32)F(2)N(3)O(2)P, (III), the tertiary N atoms of the dibenzylamido groups have sp(2) character with minimal deviation from planarity. The sums of the three bond angles about the N atoms in (I)-(III) deviate by less than 8° from the planar value of 360°. The geometries of the tertiary N atoms in all phosphoric triamides with C(O)NHP(O)[N](2) skeletons deposited in the Cambridge Structural Database [CSD; Allen (2002). Acta Cryst. B58, 380-388] have been examined and the bond-angle sums at the two tertiary N atoms (SUM1 and SUM2) and the parameter ΔSUM (= SUM1 - SUM2) considered. It was found that in compounds with a considerable ΔSUM value, the more pyramidal N atoms are usually oriented so that the corresponding lone electron pair is anti with respect to the P=O group. In (I), (II) and (III), the phosphoryl and carbonyl groups, separated by an N atom, are anti with respect to each other. In the C(O)NHP(O) fragment of (I)-(III), the P-N bond is longer and the O-P-N angle is contracted compared with the other two P-N bonds and the O-P-N angles in the molecules. These effects are also seen in analogous compounds deposited in the CSD. Compounds with [C(O)NH]P(O)[N]X (X ≠ N), such as compounds with a [C(O)NH]P(O)[N][O] skeleton, have not been considered here. Also, compounds with a [C(O)NH](2)P(O)[N] fragment have not been reported to date. In the crystal structures of all three title compounds, adjacent molecules are linked via pairs of P=O···H-N hydrogen bonds, forming dimers with C(i) symmetry.

  2. Crystal structure of an unknown solvate of dodecakis­(μ2-alaninato-1:2κ2 O:N,O)cerium(III)hexa­nickel(II) aqua­tris­(hydroxido-κO)tris­(nitrato-κ2 O,O′)cerate(III)

    PubMed Central

    Bezzubov, Stanislav I.; Doljenko, Vladimir D.; Churakov, Andrei V.; Zharinova, Irina S.; Kiselev, Yuri M.

    2015-01-01

    The chiral title compound, [CeNi6(C3H6NO2)12][Ce(NO3)3(OH)3(H2O)], comprises a complex heterometallic Ni/Ce cation and a homonuclear Ce anion. Both the cation and anion exhibit point group symmetry 3. with the CeIII atom situated on the threefold rotation axis. The cation metal core consists of six NiII atoms coordinated in a slightly distorted octa­hedral N2O4 configuration by N and O atoms of 12 deprotonated l-alaninate ligands exhibiting both bridging and chelating modes. This metal–organic coordination motif encapsulates one CeIII atom that shows an icosa­hedral coordination by the O-donor atoms of the l-alaninate ligands, with Ce—O distances varying in the range 2.455 (5)–2.675 (3) Å. In the anion, the central CeIII ion is bound to three bidentate nitrate ligands, to three hydroxide ligands and to one water mol­ecule, with Ce—O distances in the range 2.6808 (19)–2.741 (2) Å. The H atoms of the coordinating water mol­ecule are disordered over three positions due to its location on a threefold rotation axis. Disorder is also observed in fragments of two l-alaninate ligands, with occupancy ratios of 0.608 (14):0.392 (14) and 0.669 (8):0.331 (8), respectively, for the two sets of sites. In the crystal, the complex cations and anions assemble through O—H⋯O and N—H⋯O hydrogen bonds into a three-dimensional network with large voids of approximately 1020 Å3. The contributions of highly disordered ethanol and water solvent mol­ecules to the diffraction data were removed with the SQUEEZE procedure [Spek (2015 ▸). Acta Cryst. C71, 9–18]. The given chemical formula and other crystal data do not take into account the unknown amount of these solvent mol­ecules. PMID:26594427

  3. Crystal structures of a copper(II) and the isotypic nickel(II) and palladium(II) complexes of the ligand (E)-1-[(2,4,6-tri­bromo­phen­yl)diazen­yl]naphthalen-2-ol

    PubMed Central

    Chetioui, Souheyla; Rouag, Djamil-Azzeddine; Djukic, Jean-Pierre; Bochet, Christian G.; Touzani, Rachid; Bailly, Corinne; Crochet, Aurélien; Fromm, Katharina M.

    2016-01-01

    In the copper(II) complex, bis­{(E)-1-[(2,4,6-tri­bromo­phen­yl)diazen­yl]naph­thalen-2-olato}copper(II), [Cu(C16H8Br3N2O)2], (I), the metal cation is coord­inated by two N atoms and two O atoms from two bidentate (E)-1-[(2,4,6-tri­bromo­phen­yl)diazen­yl]naphthalen-2-olate ligands, forming a slightly distorted square-planar environment. In one of the ligands, the tri­bromo­benzene ring is inclined to the naphthalene ring system by 37.4 (5)°, creating a weak intra­molecular Cu⋯Br inter­action [3.134 (2) Å], while in the other ligand, the tri­bromo­benzene ring is inclined to the naphthalene ring system by 72.1 (6)°. In the isotypic nickel(II) and palladium(II) complexes, namely bis­{(E)-1-[(2,4,6-tri­bromo­phen­yl)diazen­yl]naphthalen-2-olato}nickel(II), [Ni(C16H8Br3N2O)2], (II), and bis­{(E)-1-[(2,4,6-tri­bromo­phen­yl)diazen­yl]naphthalen-2-olato}palladium(II), [Pd(C16H8Br3N2O)2], (III), respectively, the metal atoms are located on centres of inversion, hence the metal coordination spheres have perfect square-planar geometries. The tri­bromo­benzene rings are inclined to the naphthalene ring systems by 80.79 (18)° in (II) and by 80.8 (3)° in (III). In the crystal of (I), mol­ecules are linked by C—H⋯Br hydrogen bonds, forming chains along [010]. The chains are linked by C—H⋯π inter­actions, forming sheets parallel to (011). In the crystals of (II) and (III), mol­ecules are linked by C—H⋯π inter­actions, forming slabs parallel to (10-1). For the copper(II) complex (I), a region of disordered electron density was corrected for using the SQUEEZE routine in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9–18]. The formula mass and unit-cell characteristics of the disordered solvent mol­ecules were not taken into account during refinement. PMID:27536389

  4. Geometry of trigonal boron coordination sphere in boronic acids derivatives - a bond-valence vector model approach.

    PubMed

    Czerwińska, Karolina; Madura, Izabela D; Zachara, Janusz

    2016-04-01

    The systematic analysis of the geometry of three-coordinate boron in boronic acid derivatives with a common [CBO2] skeleton is presented. The study is based on the bond-valence vector (BVV) model [Zachara (2007). Inorg. Chem. 46, 9760-9767], a simple tool for the identification and quantitative estimation of both steric and electronic factors causing deformations of the coordination sphere. The empirical bond-valence (BV) parameters in the exponential equation [Brown & Altermatt (1985). Acta Cryst. B41, 244-247] rij and b, for B-O and B-C bonds were determined using data deposited in the Cambridge Structural Database. The values obtained amount to rBO = 1.364 Å, bBO = 0.37 Å, rBC = 1.569 Å, bBC = 0.28 Å, and they were further used in the calculation of BVV lengths. The values of the resultant BVV were less than 0.10 v.u. for 95% of the set comprising 897 [CBO2] fragments. Analysis of the distribution of BVV components allowed for the description of subtle in- and out-of plane deviations from the `ideal' (sp(2)) geometry of boron coordination sphere. The distortions specific for distinct groups of compounds such as boronic acids, cyclic and acyclic esters, benzoxaboroles and hemiesters were revealed. In cyclic esters the direction of strains was found to be controlled by the ring size effect. It was shown that the syn or anti location of substituents on O atoms is decisive for the deformations direction for both acids and acyclic esters. The greatest strains were observed in the case of benzoxaboroles which showed the highest deviation from the zero value of the resultant BVV. The out-of-plane distortions, described by the vz component of the resultant BVV, were ascertained to be useful in the identification of weak secondary interactions on the fourth coordination site of the boron centre. PMID:27048726

  5. Crystal structures of a copper(II) and the isotypic nickel(II) and palladium(II) complexes of the ligand (E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naphthalen-2-ol.

    PubMed

    Chetioui, Souheyla; Rouag, Djamil-Azzeddine; Djukic, Jean-Pierre; Bochet, Christian G; Touzani, Rachid; Bailly, Corinne; Crochet, Aurélien; Fromm, Katharina M

    2016-08-01

    In the copper(II) complex, bis-{(E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naph-thalen-2-olato}copper(II), [Cu(C16H8Br3N2O)2], (I), the metal cation is coord-inated by two N atoms and two O atoms from two bidentate (E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naphthalen-2-olate ligands, forming a slightly distorted square-planar environment. In one of the ligands, the tri-bromo-benzene ring is inclined to the naphthalene ring system by 37.4 (5)°, creating a weak intra-molecular Cu⋯Br inter-action [3.134 (2) Å], while in the other ligand, the tri-bromo-benzene ring is inclined to the naphthalene ring system by 72.1 (6)°. In the isotypic nickel(II) and palladium(II) complexes, namely bis-{(E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naphthalen-2-olato}nickel(II), [Ni(C16H8Br3N2O)2], (II), and bis-{(E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naphthalen-2-olato}palladium(II), [Pd(C16H8Br3N2O)2], (III), respectively, the metal atoms are located on centres of inversion, hence the metal coordination spheres have perfect square-planar geometries. The tri-bromo-benzene rings are inclined to the naphthalene ring systems by 80.79 (18)° in (II) and by 80.8 (3)° in (III). In the crystal of (I), mol-ecules are linked by C-H⋯Br hydrogen bonds, forming chains along [010]. The chains are linked by C-H⋯π inter-actions, forming sheets parallel to (011). In the crystals of (II) and (III), mol-ecules are linked by C-H⋯π inter-actions, forming slabs parallel to (10-1). For the copper(II) complex (I), a region of disordered electron density was corrected for using the SQUEEZE routine in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The formula mass and unit-cell characteristics of the disordered solvent mol-ecules were not taken into account during refinement.

  6. PLATON SQUEEZE: a tool for the calculation of the disordered solvent contribution to the calculated structure factors.

    PubMed

    Spek, Anthony L

    2015-01-01

    The completion of a crystal structure determination is often hampered by the presence of embedded solvent molecules or ions that are seriously disordered. Their contribution to the calculated structure factors in the least-squares refinement of a crystal structure has to be included in some way. Traditionally, an atomistic solvent disorder model is attempted. Such an approach is generally to be preferred, but it does not always lead to a satisfactory result and may even be impossible in cases where channels in the structure are filled with continuous electron density. This paper documents the SQUEEZE method as an alternative means of addressing the solvent disorder issue. It conveniently interfaces with the 2014 version of the least-squares refinement program SHELXL [Sheldrick (2015). Acta Cryst. C71. In the press] and other refinement programs that accept externally provided fixed contributions to the calculated structure factors. The PLATON SQUEEZE tool calculates the solvent contribution to the structure factors by back-Fourier transformation of the electron density found in the solvent-accessible region of a phase-optimized difference electron-density map. The actual least-squares structure refinement is delegated to, for example, SHELXL. The current versions of PLATON SQUEEZE and SHELXL now address several of the unnecessary complications with the earlier implementation of the SQUEEZE procedure that were a necessity because least-squares refinement with the now superseded SHELXL97 program did not allow for the input of fixed externally provided contributions to the structure-factor calculation. It is no longer necessary to subtract the solvent contribution temporarily from the observed intensities to be able to use SHELXL for the least-squares refinement, since that program now accepts the solvent contribution from an external file (.fab file) if the ABIN instruction is used. In addition, many twinned structures containing disordered solvents are now also

  7. Crystal structures of tris-[1-oxo-pyridine-2-olato(1-)]silicon(IV) chloride chloro-form-d 1 disolvate, tris-[1-oxo-pyridine-2-olato(1-)]silicon(IV) chloride aceto-nitrile unqu-anti-fied solvate, and fac-tris-[1-oxo-pyridine-2-thiol-ato(1-)]silicon(IV) chloride chloro-form-d 1 disolvate.

    PubMed

    Kraft, Bradley M; Brennessel, William W; Ryan, Amy E; Benjamin, Candace K

    2015-12-01

    The cations in the title salts, [Si(OPO)3]Cl·2CDCl3, (I), [Si(OPO)3]Cl·xCH3CN, (II), and fac-[Si(OPTO)3]Cl·2CDCl3, (III) (OPO = 1-oxo-2-pyridin-one, C5H4NO2, and OPTO = 1-oxo-2-pyridine-thione, C5H4NOS), have distorted octa-hedral coordination spheres. The first two structures contain the same cation and anion, but different solvents of crystallization led to different solvates and packing arrangements. In structures (I) and (III), the silicon complex cations and chloride anions are well separated, while in (II), there are two C-H⋯Cl distances that fall just within the sum of the van der Waals radii of the C and Cl atoms. The pyridine portions of the OPO ligands in (I) and (II) are modeled as disordered with the planar flips of themselves [(I): 0.574 (15):0.426 (15), 0.696 (15):0.304 (15), and 0.621 (15):0.379 (15); (II): 0.555 (13):0.445 (13), 0.604 (14):0.396 (14) and 0.611 (13):0.389 (13)], demonstrating that both fac and mer isomers are co-crystallized. In (II), highly disordered solvent, located in two independent channels along [100], was unable to be modeled. Reflection contributions from this solvent were fixed and added to the calculated structure factors using the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] function of program PLATON, which determined there to be 54 electrons in 225 Å(3) accounted for per unit cell (25 electrons in 109 Å(3) in one channel, and 29 electrons in 115 Å(3) in the other). In (I) and (II), all species lie on general positions. In (III), all species are located along crystallographic threefold axes.

  8. Polymorphism of NaVO2F2: a P2₁/c superstructure with pseudosymmetry of P2₁/m in the subcell.

    PubMed

    Yu, Zi-Qun; Wang, Jing-Quan; Huang, Ya-Xi; Botis, Sanda M; Pan, Yuanming; Mi, Jin-Xiao

    2015-06-01

    The ADDSYM routine in the program PLATON [Spek (2015). Acta Cryst. C71, 9-18] has helped researchers to avoid structures of (metal-)organic compounds being reported in an unnecessarily low symmetry space group. However, determination of the correct space group may get more complicated in cases of pseudosymmetric inorganic compounds. One example is NaVO2F2, which was reported [Crosnier-Lopez et al. (1994). Eur. J. Solid State Inorg. Chem. 31, 957-965] in the acentric space group P2₁ based on properties but flagged by ADDSYM as (pseudo)centrosymmetric P2₁/m within default distance tolerances. Herein a systematic investigation reveals that NaVO2F2 exists in at least four polymorphs: P2₁, (I), P2₁/m, (II), P2₁/c, (III), and one or more low-temperature ones. The new centrosymmetric modification, (III), with the space group P2₁/c has a similar atomic packing geometry to phase (I), except for having a doubled c axis. The double-cell of phase (III) arises from atomic shifts from the glide plane c at (x, ¼, z). With increasing temperature, the number of observed reflections decreases. The odd l reflections gradually become weaker and, correspondingly, all atoms shift towards the glide plane, resulting in a gradual second-order transformation of (III) into high-temperature phase (II) (P2₁/m) at below 493 K. At least one first-order enantiotropic phase transition was observed below 139 K from both the single-crystal X-ray diffraction and the differential scanning calorimetry analyses. Periodic first-principles calculations within density functional theory show that both P2₁/c superstructure (III) and P2₁ substructure (I) are more stable than P2₁/m structure (II), and that P2₁/c superstructure (III) is more stable that P2₁ substructure (I).

  9. Crystal packing in three related disaccharides: precursors to heparan sulfate oligosaccharides

    PubMed Central

    Gainsford, Graeme J.; Schwörer, Ralf; Tyler, Peter C.; Zubkova, Olga V.

    2015-01-01

    The three title compounds form part of a set of important precursor dissacharides which lead to novel therapeutics, in particular for Alzheimer’s disease. All three crystallize as poorly diffracting crystals with one independent mol­ecule in the asymmetric unit. Two of them are isostructural: 4-meth­oxy­phenyl 4-O-[6-O-acetyl-2-azido-3-O-benzyl-2-de­oxy-4-O-(9-fluor­en­yl­methyl­oxycarbon­yl)-α-d-gluco­pyranos­yl]-2-O-benzoyl-3-O-benzyl-6-O-chloro­acetyl-α-l-ido­pyran­oside, C59H56ClN3O16, (I), the ido-relative of a reported gluco-disaccharide [Gainsford et al., 2013 ▸). Acta Cryst. C69, 679–682] and 4-meth­oxy­phenyl 4-O-[6-O-acetyl-2-azido-3-O-benzyl-2-de­oxy-4-O-(9-fluorenyl­methyl­oxycarbon­yl)-α-d-gluco­pyranos­yl]-2-O-benzoyl-3-O-benzyl-6-O-meth­oxy­acetyl-α-l-ido­pyran­oside, C60H59N3O17, (II). Both exhibit similar conformational disorder of pendant groups. The third compound 4-meth­oxy­phenyl 4-O-[6-O-acetyl-2-azido-3,4-di-O-benzyl-2-de­oxy-α-d-gluco­pyranos­yl]-2-O-benzoyl-3-O-benzyl-6-O-meth­oxy­oacetyl-β-d-gluco­pyran­oside, C52H55N3O15, (III), illustrates that a slightly larger set of weak inter­molecular inter­actions can result in a less disordered mol­ecular arrangement. The mol­ecules are bound by weak C—H⋯O(ether) hydrogen bonds in (I) and (II), augmented by C—H⋯π inter­actions in (III). The absolute configurations were determined, although at varying levels of significance from the limited observed data. PMID:26090127

  10. Crystal structure of 4'-{[4-(2,2':6',2''-terpyrid-yl-4'-yl)phen-yl]ethyn-yl}biphenyl-4-yl (2,2,5,5-tetra-methyl-1-oxyl-3-pyrrolin-3-yl)formate benzene 2.5-solvate.

    PubMed

    Meyer, Andreas; Schnakenburg, Gregor; Schiemann, Olav

    2015-10-01

    ethynylphenyl spacer [Meyer et al. (2015). Acta Cryst. E71, 870-874]. PMID:26594417

  11. Radiation damage effects in zircon

    NASA Astrophysics Data System (ADS)

    Trachenko, Kostya; Dove, Martin; Salje, Ekhard

    2002-03-01

    Zircon, ZrSiO_4, is important for geology and geochronology, and has been proposed as a host material to immobilize highly radioactive materials from dismantled weapons and nuclear waste from power stations [1]. In these applications zircon is exposed to alpha-irradiation. Computer simulations have started to be employed to simulate radiation damage in zircon [2], but the origin and microscopic mechanisms of the most important structural changes in zircon - unit cell expansion and large macroscopic swelling at higher doses, strong shear deformation of the crystalline lattice, and polymerization of SiOn units [3], remain unknown. Here, we perform the molecular dynamics simulation of highly energetic recoils in zircon. Basing on the simulation results, we propose the simple picture of the density change in the damaged region that consists of the depleted and densified matter. We find that the experimentally observed structural changes originate from the interaction of the damaged region with the surrounding crystalline lattice: the shear of the lattice around the damaged region causes shear deformation and expansion of the unit cells. The polymers of connected SiOn polyhedra are most commonly present in the densified shell at the periphery of the damaged region. [1] R C Ewing et al, J. Mater. Res. 10, 243 (1995); W J Weber et al, B E Burakov et al, in Scientific Basis for Nuclear Waste Management XIX, 25-32 and 33-40 (Plenum, New York, 1996); R C Ewing, et al in Crystalline Ceramics: Waste Forms for the Disposal of Weapons Plutonium, NATO Workshop Proceedings 65 (Academic Publishers, Dordrecht, The Netherlands, 1996). [2] B Park et al, Phys. Rev. B, 64, 174108 (1-16) (2001); J P Crocombette and D Ghaleb, J. Nucl. Mater., 295, 167 (2001); K Trachenko et al, J. Appl. Phys., 87, 7702 (2000); K Trachenko et al, J. Phys.: Cond. Matt., 13, 1947 (2001). [3] T Murakami et al, Am. Min., 76, 1510 (1991); H D Holland and D Gottfried, Acta Cryst. 8, 291 (1955).; W J Weber, J. Am

  12. PLATON SQUEEZE: a tool for the calculation of the disordered solvent contribution to the calculated structure factors.

    PubMed

    Spek, Anthony L

    2015-01-01

    The completion of a crystal structure determination is often hampered by the presence of embedded solvent molecules or ions that are seriously disordered. Their contribution to the calculated structure factors in the least-squares refinement of a crystal structure has to be included in some way. Traditionally, an atomistic solvent disorder model is attempted. Such an approach is generally to be preferred, but it does not always lead to a satisfactory result and may even be impossible in cases where channels in the structure are filled with continuous electron density. This paper documents the SQUEEZE method as an alternative means of addressing the solvent disorder issue. It conveniently interfaces with the 2014 version of the least-squares refinement program SHELXL [Sheldrick (2015). Acta Cryst. C71. In the press] and other refinement programs that accept externally provided fixed contributions to the calculated structure factors. The PLATON SQUEEZE tool calculates the solvent contribution to the structure factors by back-Fourier transformation of the electron density found in the solvent-accessible region of a phase-optimized difference electron-density map. The actual least-squares structure refinement is delegated to, for example, SHELXL. The current versions of PLATON SQUEEZE and SHELXL now address several of the unnecessary complications with the earlier implementation of the SQUEEZE procedure that were a necessity because least-squares refinement with the now superseded SHELXL97 program did not allow for the input of fixed externally provided contributions to the structure-factor calculation. It is no longer necessary to subtract the solvent contribution temporarily from the observed intensities to be able to use SHELXL for the least-squares refinement, since that program now accepts the solvent contribution from an external file (.fab file) if the ABIN instruction is used. In addition, many twinned structures containing disordered solvents are now also

  13. Crystal structures of tris-[1-oxo-pyridine-2-olato(1-)]silicon(IV) chloride chloro-form-d 1 disolvate, tris-[1-oxo-pyridine-2-olato(1-)]silicon(IV) chloride aceto-nitrile unqu-anti-fied solvate, and fac-tris-[1-oxo-pyridine-2-thiol-ato(1-)]silicon(IV) chloride chloro-form-d 1 disolvate.

    PubMed

    Kraft, Bradley M; Brennessel, William W; Ryan, Amy E; Benjamin, Candace K

    2015-12-01

    The cations in the title salts, [Si(OPO)3]Cl·2CDCl3, (I), [Si(OPO)3]Cl·xCH3CN, (II), and fac-[Si(OPTO)3]Cl·2CDCl3, (III) (OPO = 1-oxo-2-pyridin-one, C5H4NO2, and OPTO = 1-oxo-2-pyridine-thione, C5H4NOS), have distorted octa-hedral coordination spheres. The first two structures contain the same cation and anion, but different solvents of crystallization led to different solvates and packing arrangements. In structures (I) and (III), the silicon complex cations and chloride anions are well separated, while in (II), there are two C-H⋯Cl distances that fall just within the sum of the van der Waals radii of the C and Cl atoms. The pyridine portions of the OPO ligands in (I) and (II) are modeled as disordered with the planar flips of themselves [(I): 0.574 (15):0.426 (15), 0.696 (15):0.304 (15), and 0.621 (15):0.379 (15); (II): 0.555 (13):0.445 (13), 0.604 (14):0.396 (14) and 0.611 (13):0.389 (13)], demonstrating that both fac and mer isomers are co-crystallized. In (II), highly disordered solvent, located in two independent channels along [100], was unable to be modeled. Reflection contributions from this solvent were fixed and added to the calculated structure factors using the SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18] function of program PLATON, which determined there to be 54 electrons in 225 Å(3) accounted for per unit cell (25 electrons in 109 Å(3) in one channel, and 29 electrons in 115 Å(3) in the other). In (I) and (II), all species lie on general positions. In (III), all species are located along crystallographic threefold axes. PMID:26870422

  14. Polymorphism of NaVO2F2: a P2₁/c superstructure with pseudosymmetry of P2₁/m in the subcell.

    PubMed

    Yu, Zi-Qun; Wang, Jing-Quan; Huang, Ya-Xi; Botis, Sanda M; Pan, Yuanming; Mi, Jin-Xiao

    2015-06-01

    The ADDSYM routine in the program PLATON [Spek (2015). Acta Cryst. C71, 9-18] has helped researchers to avoid structures of (metal-)organic compounds being reported in an unnecessarily low symmetry space group. However, determination of the correct space group may get more complicated in cases of pseudosymmetric inorganic compounds. One example is NaVO2F2, which was reported [Crosnier-Lopez et al. (1994). Eur. J. Solid State Inorg. Chem. 31, 957-965] in the acentric space group P2₁ based on properties but flagged by ADDSYM as (pseudo)centrosymmetric P2₁/m within default distance tolerances. Herein a systematic investigation reveals that NaVO2F2 exists in at least four polymorphs: P2₁, (I), P2₁/m, (II), P2₁/c, (III), and one or more low-temperature ones. The new centrosymmetric modification, (III), with the space group P2₁/c has a similar atomic packing geometry to phase (I), except for having a doubled c axis. The double-cell of phase (III) arises from atomic shifts from the glide plane c at (x, ¼, z). With increasing temperature, the number of observed reflections decreases. The odd l reflections gradually become weaker and, correspondingly, all atoms shift towards the glide plane, resulting in a gradual second-order transformation of (III) into high-temperature phase (II) (P2₁/m) at below 493 K. At least one first-order enantiotropic phase transition was observed below 139 K from both the single-crystal X-ray diffraction and the differential scanning calorimetry analyses. Periodic first-principles calculations within density functional theory show that both P2₁/c superstructure (III) and P2₁ substructure (I) are more stable than P2₁/m structure (II), and that P2₁/c superstructure (III) is more stable that P2₁ substructure (I). PMID:26044323

  15. Molecular replacement then and now

    SciTech Connect

    Scapin, Giovanna

    2013-11-01

    A brief overview, with examples, of the evolution of molecular-replacement methods and models over the past few years is presented. The ‘phase problem’ in crystallography results from the inability to directly measure the phases of individual diffracted X-ray waves. While intensities are directly measured during data collection, phases must be obtained by other means. Several phasing methods are available (MIR, SAR, MAD, SAD and MR) and they all rely on the premise that phase information can be obtained if the positions of marker atoms in the unknown crystal structure are known. This paper is dedicated to the most popular phasing method, molecular replacement (MR), and represents a personal overview of the development, use and requirements of the methodology. The first description of noncrystallographic symmetry as a tool for structure determination was explained by Rossmann and Blow [Rossmann & Blow (1962 ▶), Acta Cryst.15, 24–31]. The term ‘molecular replacement’ was introduced as the name of a book in which the early papers were collected and briefly reviewed [Rossmann (1972 ▶), The Molecular Replacement Method. New York: Gordon & Breach]. Several programs have evolved from the original concept to allow faster and more sophisticated searches, including six-dimensional searches and brute-force approaches. While careful selection of the resolution range for the search and the quality of the data will greatly influence the outcome, the correct choice of the search model is probably still the main criterion to guarantee success in solving a structure using MR. Two of the main parameters used to define the ‘best’ search model are sequence identity (25% or more) and structural similarity. Another parameter that may often be undervalued is the quality of the probe: there is clearly a relationship between the quality and the correctness of the chosen probe and its usefulness as a search model. Efforts should be made by all structural biologists to

  16. Checking nucleic acid crystal structures.

    PubMed

    Das, U; Chen, S; Fuxreiter, M; Vaguine, A A; Richelle, J; Berman, H M; Wodak, S J

    2001-06-01

    The program SFCHECK [Vaguine et al. (1999), Acta Cryst. D55, 191-205] is used to survey the quality of the structure-factor data and the agreement of those data with the atomic coordinates in 105 nucleic acid crystal structures for which structure-factor amplitudes have been deposited in the Nucleic Acid Database [NDB; Berman et al. (1992), Biophys. J. 63, 751-759]. Nucleic acid structures present a particular challenge for structure-quality evaluations. The majority of these structures, and DNA molecules in particular, have been solved by molecular replacement of the double-helical motif, whose high degree of symmetry can lead to problems in positioning the molecule in the unit cell. In this paper, the overall quality of each structure was evaluated using parameters such as the R factor, the correlation coefficient and various atomic error estimates. In addition, each structure is characterized by the average values of several local quality indicators, which include the atomic displacement, the density correlation, the B factor and the density index. The latter parameter measures the relative electron-density level at the atomic position. In order to assess the quality of the model in specific regions, the same local quality indicators are also surveyed for individual groups of atoms in each structure. Several of the global quality indicators are found to vary linearly with resolution and less than a dozen structures are found to exhibit values significantly different from the mean for these indicators, showing that the quality of the nucleic acid structures tends to be rather uniform. Analysis of the mutual dependence of the values of different local quality indicators, computed for individual residues and atom groups, reveals that these indicators essentially complement each other and are not redundant with the B factor. Using several of these indicators, it was found that the atomic coordinates of the nucleic acid bases tend to be better defined than those of

  17. Structure of lobster apocrustacyanin A1 using softer X-rays.

    PubMed

    Cianci, M; Rizkallah, P J; Olczak, A; Raftery, J; Chayen, N E; Zagalsky, P F; Helliwell, J R

    2001-09-01

    The molecular basis of the camouflage colouration of marine crustacea is often provided by carotenoproteins. The blue colour of the lobster carapace, for example, is intricately associated with a multimacromolecular 16-mer complex of protein subunits each with a bound astaxanthin molecule. The protein subunits of crustacyanin fall into two distinct subfamilies, CRTC and CRTA. Here, the crystal structure solution of the A(1) protein of the CRTC subfamily is reported. The problematic nature of the structure solution of the CRTC proteins (both C(1) and A(1)) warranted consideration and the development of new approaches. Three putative disulfides per protein subunit were likely to exist based on molecular-homology modelling against known lipocalin protein structures. With two such subunits per crystallographic asymmetric unit, this direct approach was still difficult as it involved detecting a weak signal from these sulfurs and suggested the use of softer X-rays, combined with high data multiplicity, as reported previously [Chayen et al. (2000), Acta Cryst. D56, 1064-1066]. This paper now describes the structure solution of CRTC in the form of the A(1) dimer based on use of softer X-rays (2 A wavelength). The structure solution involved a xenon derivative with an optimized xenon L(I) edge f" signal and a native data set. The hand of the xenon SIROAS phases was determined by using the sulfur anomalous signal from a high-multiplicity native data set also recorded at 2 A wavelength. For refinement, a high-resolution data set was measured at short wavelength. All four data sets were collected at 100 K. The refined structure to 1.4 A resolution based on 60 276 reflections has an R factor of 17.7% and an R(free) of 22.9% (3137 reflections). The structure is that of a typical lipocalin, being closely related to insecticyanin, to bilin-binding protein and to retinol-binding protein. This A(1) monomer or dimer can now be used as a search motif in the structural studies of the

  18. Crystal structures of a copper(II) and the isotypic nickel(II) and palladium(II) complexes of the ligand (E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naphthalen-2-ol.

    PubMed

    Chetioui, Souheyla; Rouag, Djamil-Azzeddine; Djukic, Jean-Pierre; Bochet, Christian G; Touzani, Rachid; Bailly, Corinne; Crochet, Aurélien; Fromm, Katharina M

    2016-08-01

    In the copper(II) complex, bis-{(E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naph-thalen-2-olato}copper(II), [Cu(C16H8Br3N2O)2], (I), the metal cation is coord-inated by two N atoms and two O atoms from two bidentate (E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naphthalen-2-olate ligands, forming a slightly distorted square-planar environment. In one of the ligands, the tri-bromo-benzene ring is inclined to the naphthalene ring system by 37.4 (5)°, creating a weak intra-molecular Cu⋯Br inter-action [3.134 (2) Å], while in the other ligand, the tri-bromo-benzene ring is inclined to the naphthalene ring system by 72.1 (6)°. In the isotypic nickel(II) and palladium(II) complexes, namely bis-{(E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naphthalen-2-olato}nickel(II), [Ni(C16H8Br3N2O)2], (II), and bis-{(E)-1-[(2,4,6-tri-bromo-phen-yl)diazen-yl]naphthalen-2-olato}palladium(II), [Pd(C16H8Br3N2O)2], (III), respectively, the metal atoms are located on centres of inversion, hence the metal coordination spheres have perfect square-planar geometries. The tri-bromo-benzene rings are inclined to the naphthalene ring systems by 80.79 (18)° in (II) and by 80.8 (3)° in (III). In the crystal of (I), mol-ecules are linked by C-H⋯Br hydrogen bonds, forming chains along [010]. The chains are linked by C-H⋯π inter-actions, forming sheets parallel to (011). In the crystals of (II) and (III), mol-ecules are linked by C-H⋯π inter-actions, forming slabs parallel to (10-1). For the copper(II) complex (I), a region of disordered electron density was corrected for using the SQUEEZE routine in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The formula mass and unit-cell characteristics of the disordered solvent mol-ecules were not taken into account during refinement. PMID:27536389

  19. Structural analysis of human dihydrofolate reductase as a binary complex with the potent and selective inhibitor 2,4-diamino-6-{2'-O-(3-carboxypropyl)oxydibenz[b,f]-azepin-5-yl}methylpteridine reveals an unusual binding mode.

    PubMed

    Cody, Vivian; Pace, Jim; Nowak, Jessica

    2011-10-01

    In order to understand the structure-activity profile observed for a series of substituted dibenz[b,f]azepine antifolates, the crystal structure of the binary complex of human dihydrofolate reductase (hDHFR) with the potent and selective inhibitor 2,4-diamino-6-{2'-O-(3-carboxypropyl)oxydibenz[b,f]-azepin-5-yl}methylpteridine (PT684) was determined to 1.8 Å resolution. These data revealed that the carboxylate side chain of PT684 occupies two alternate positions, neither of which interacts with the conserved Arg70 in the active-site pocket, which in turn hydrogen bonds to water. These observations are in contrast to those reported for the ternary complex of mouse DHFR (mDHFR) with NADPH [Cody et al. (2008), Acta Cryst. D64, 977-984], in which the 3-carboxypropyl side chain of PT684 was hydrolyzed to its hydroxyl derivative, PT684a. The crystallization conditions differed for the human and mouse DHFR crystals (100 mM K2HPO4 pH 6.9, 30% ammonium sulfate for hDHFR; 15 mM Tris pH 8.3, 75 mM sodium cacodylate, PEG 4K for mDHFR). Additionally, the side chains of Phe31 and Gln35 in the hDHFR complex have a single conformation, whereas in the mDHFR complex they occupied two alternative conformations. These data show that the hDHFR complex has a decreased active-site volume compared with the mDHFR complex, as reflected in a relative shift of helix C (residues 59-64) of 1.2 Å, and a shift of 1.5 Å compared with the ternary complex of Pneumocystis carinii DHFR (pcDHFR) with the parent dibenz[b,f]azepine PT653. These data suggest that the greater inhibitory potency of PT684 against pcDHFR is consistent with the larger active-site volume of pcDHFR and the predicted interactions of the carboxylate side chain with Arg75.

  20. Importance of the consideration of anharmonic motion in charge-density studies: a comparison of variable-temperature studies on two explosives, RDX and HMX.

    PubMed

    Zhurov, Vladimir V; Zhurova, Elizabeth A; Stash, Adam I; Pinkerton, A Alan

    2011-03-01

    Extremely accurate X-ray data were obtained for the explosive RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) at three different temperatures (20, 120 and 298 K). Collected reflections were integrated using the latest version of the program VIIPP which uses separate Kα(1)/Kα(2) contributions to the profile fitting during integration. For each temperature both anharmonic and harmonic descriptions of the atomic thermal motion were utilized in the model refinements along with the multipole expansion of the electron density. H atoms were refined anisotropically and agree well with a previous neutron study. Topological analysis [Bader (1990). Atoms in Molecules: A Quantum Theory. The International Series of Monographs of Chemistry, edited by J. Halpern & M. L. H. Green. Oxford: Clarendon Press] of the attained electron density followed. For 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), old data collected at 20 and 120 K were re-integrated with the new version of VIIPP and refined in the same manner as for RDX. In both cases theoretical structure factors were also calculated based on the 20 K structures, and employed in comparison multipole refinements for the atoms at rest. Limiting the refinement to a harmonic model of the atomic displacements may result in a biased and erroneous electron density, especially when atomic vibrations are significant (as in RDX) and at temperatures higher than obtained by using liquid helium. Given the similarity of the two compounds the effects of anharmonic motion are strikingly more severe in the case of RDX. Our study reinforces the conclusion of Meindl et al. [Acta Cryst. (2010), A66, 362-371] that in certain cases it is necessary to include anharmonic term(s) of the probability density function (or temperature factor) in order to obtain a meaningful electron density suitable for topological analysis, even for compact (high-density) light-atom structures. For RDX it was observed that the oxygen lone-pair concentrations of

  1. Adaptive continuous twisting algorithm

    NASA Astrophysics Data System (ADS)

    Moreno, Jaime A.; Negrete, Daniel Y.; Torres-González, Victor; Fridman, Leonid

    2016-09-01

    In this paper, an adaptive continuous twisting algorithm (ACTA) is presented. For double integrator, ACTA produces a continuous control signal ensuring finite time convergence of the states to zero. Moreover, the control signal generated by ACTA compensates the Lipschitz perturbation in finite time, i.e. its value converges to the opposite value of the perturbation. ACTA also keeps its convergence properties, even in the case that the upper bound of the derivative of the perturbation exists, but it is unknown.

  2. The Behaviors that College Students Classify as Political Bias: Preliminary Findings and Implications

    ERIC Educational Resources Information Center

    Tollini, Craig

    2009-01-01

    There have been a number of recently published books and reports about the existence of a liberal bias in academia (e.g., ACTA 2005, ACTA 2006, Berube 2006, Black 2004, Horowitz 2006, Horowitz 2008, and Shapiro 2004). Sociology is one of the disciplines that is most frequently cited as "producers" of bias in two of these studies (ACTA 2006,…

  3. What Will They Learn? 2012-13. A Survey of Core Requirements at Our Nation's Colleges and Universities

    ERIC Educational Resources Information Center

    Kempson, Lauri; Bako, Tom; Lewin, Greg

    2012-01-01

    The American Council of Trustees and Alumni (ACTA) has released "What Will They Learn? 2012-13," the fourth edition, evaluating the general education requirements at 1,070 colleges and universities. Unlike other college rankings, ACTA does not consider an institution's wealth, prestige, or popularity. Rather, ACTA rates institutions…

  4. Data processing pipeline for serial femtosecond crystallography at SACLA1

    PubMed Central

    Nakane, Takanori; Joti, Yasumasa; Tono, Kensuke; Yabashi, Makina; Nango, Eriko; Iwata, So; Ishitani, Ryuichiro; Nureki, Osamu

    2016-01-01

    A data processing pipeline for serial femtosecond crystallography at SACLA was developed, based on Cheetah [Barty et al. (2014). J. Appl. Cryst.47, 1118–1131] and CrystFEL [White et al. (2016). J. Appl. Cryst.49, 680–689]. The original programs were adapted for data acquisition through the SACLA API, thread and inter-node parallelization, and efficient image handling. The pipeline consists of two stages: The first, online stage can analyse all images in real time, with a latency of less than a few seconds, to provide feedback on hit rate and detector saturation. The second, offline stage converts hit images into HDF5 files and runs CrystFEL for indexing and integration. The size of the filtered compressed output is comparable to that of a synchrotron data set. The pipeline enables real-time feedback and rapid structure solution during beamtime. PMID:27275146

  5. 75 FR 6762 - Self-Regulatory Organizations; Chicago Board Options Exchange, Incorporated; Notice of Filing and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-10

    ... Bradesco SA. OXY Occidental Petroleum Corp. BCRX BioCryst Pharmaceuticals Inc. PARD Poniard Pharmaceuticals... Foods Inc. 2. Statutory Basis The Exchange believes the rule proposal is consistent with the...

  6. Response to comments on the papers recently published by Kalaivani et al.

    NASA Astrophysics Data System (ADS)

    Kalaivani, D.; Jayaraman, D.; Joseph, V.

    2016-04-01

    We argue that the crystal 1. L-lysinium succinate (LLMS) (D. Kalaivani et al J. Cryst. Growth 426 (2015) 135-140), 2. Zinc chloride doped lysinium succinate (ZnCl2-Lls) (D. Kalaivani et al. J. Cryst. Growth 428 (2015) 24-28) are not a dubious crystal. EDAX is the primary tool for analyzing the presence of all the elements except lighter elements.

  7. Guia del Proceso del IFSP de Colorado: Conexiones para la Ninez Temprana, Iniciativa Infantil de Colorado Parte C del Acta de Educacion para Individuos con Desabilidades (Colorado Guidelines for the IFSP Process: Early Childhood Connections, Colorado's Infant/Toddler Initiative for Part C of the Individuals with Disabilities Education Act).

    ERIC Educational Resources Information Center

    Miller, Jerri; Petersen, Sandy

    This booklet for Spanish-speaking parents of young children with disabilities describes Colorado's Individualized Family Service Plan (IFSP) process. It explains guidelines, shares family stories and reflections for families and care providers, and the describes the values that drive the IFSP process in Colorado. Information is provided on…

  8. Comment on "Structural and vibrational studies on 1-(5-Methyl- [1,3,4] thiadiazol-2-yl)-pyrolidin-2-ol" [Spectrochimica Acta Part A, 152 (2016) 252-261]. The importance of intramolecular OH ⋯ N hydrogen bonding in the conformational properties of thiadiazol-pyrrolidin-2-ol bearing species

    NASA Astrophysics Data System (ADS)

    Laurella, Sergio L.; Erben, Mauricio F.

    2016-07-01

    The title paper [1] reports a study on the spectroscopic and physicochemical properties of 1-(5-methyl- [1,3,4]thiadiazol-2-yl)-pyrrolidin-2-ol (MTPN) based on experimental and theoretical data. The latter ones are based on the computed molecular structure for a rather unusual conformer. Here, after a careful analysis of the conformational space of MTPN, the most stable conformation was determined for the molecule isolated in a vacuum, which results to be 21.9 kJ/mol more stable than the conformer reported previously. Our study also includes the closely related species 1-(5-trifluoromethyl- [1,3,4]thiadiazol-2-yl)-pyrrolidin-2-ol (FMTPN). An intramolecular OH ⋯ N hydrogen bond determines the conformational behavior of the [1,3,4]thiadiazol-2-yl)-pyrrolidin-2-ol group as demonstrated by Natural Bond Orbital population analysis.

  9. Reply to the comment by Wu et al. (2016) on "Behavior of Re and Os during contact between an aqueous solution and oil: Consequences for the application of the Re-Os geochronometer to petroleum" [Geochim. Cosmochim. Acta 158 (2015) 1-21

    NASA Astrophysics Data System (ADS)

    Reisberg, Laurie; Michels, Raymond; Mahdaoui, Fatima

    2016-08-01

    We reply here to the questions raised by Wu et al. concerning the results published by Mahdaoui et al. (2015). This paper describes experiments in which aqueous solutions containing ReO4- and OsCl62- were brought in contact with natural oils at various ranges of concentration, time and temperature. The main observation is that the transfer of Re and Os to oils is very efficient under all experimental conditions. Wu et al. argue that thermodynamic equilibrium was not achieved in these experiments as apparent partition coefficients are inconsistent. They conclude that the experiments were flawed by possible leaking of reactors and that the conclusions by Mahdaoui et al. (2015) were not justified. In the following reply we explain that Mahdaoui et al. (2015) never claimed that thermodynamic equilibrium was achieved. Any calculations or considerations in this context are therefore meaningless. We recall the objectives of our publication, which were to experimentally test the behavior of ReO4- and OsCl6- (two plausible chemical forms of Re and Os in deep aquifers of petroleum systems) in aqueous solution-oil systems. To our knowledge these are the first experiments of their kind. The parameters that could influence the precision and reproducibility of our results were discussed in detail in Mahdaoui et al. (2015). The essential point is that all 60 of the experiments provide evidence of substantial transfer of Re and Os from water to oil. In contrast to what was mistakenly understood by Wu et al., the paper does not challenge the use of Re-Os to date geological events affecting petroleum. Instead, by providing a mechanism that might allow Os isotopic homogenization on a basin-wide scale, a critical step missing from most current models, it offers a possible explanation of how Re-Os geochronology in oils could potentially work. More generally, our study suggests that transfer of Re and Os from waters to oil may be an important phenomenon that should not be overlooked.

  10. Trinuclear nickel coordination complexes of phenanthrene-9,10-dione dioxime

    PubMed Central

    Williams, Owen M.; Cowley, Alan H.

    2016-01-01

    oriented along the c axis. In the fluorido­boronate structure, the solvent (DCM) was too badly disordered to be modelled, so its contribution was removed using SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9–18]. PMID:27375884

  11. XANES and Raman spectrometry on glasses and crystals in the CAS system.

    NASA Astrophysics Data System (ADS)

    Neuville, N.; Cormier, C.; Flank, F.; Massiot, M.

    2003-04-01

    decreasing SiO2, and we interpret this decrease as a substitution of Si by Al in T4 units with other substitution of Si by Al in T3 units. From the Xanes spectra, we observed that : - Al is in tetrahedral site in different Q species in all the CAS system. - Ca is in octahedral site in all the CAS system, with a decrease of the site distorsion with increasing SiO2 content. Finally, the anomalous behavior for the viscosity and glass transition properties in the low silica glasses can be explained by the presence of Al in Q3 species. References : L. Cormier, D.R. Neuville, G. Calas, (2000) J. Non-Cryst. Solids, 274 110-114. NeuvilleD.R. and Mysen B. (1996). Geochim. Cosmochim. Acta., 60, 1727-1737.

  12. Trinuclear nickel coordination complexes of phenanthrene-9,10-dione dioxime.

    PubMed

    Williams, Owen M; Cowley, Alan H

    2016-04-01

    the fluorido-boronate structure, the solvent (DCM) was too badly disordered to be modelled, so its contribution was removed using SQUEEZE [Spek (2015 ▸). Acta Cryst. C71, 9-18]. PMID:27375884

  13. Crystal structure of 4′-{[4-(2,2′:6′,2′′-terpyrid­yl-4′-yl)phen­yl]ethyn­yl}biphenyl-4-yl (2,2,5,5-tetra­methyl-1-oxyl-3-pyrrolin-3-yl)formate benzene 2.5-solvate

    PubMed Central

    Meyer, Andreas; Schnakenburg, Gregor; Schiemann, Olav

    2015-01-01

    ′-terpyridine (3), which has an ethynylphenyl spacer [Meyer et al. (2015). Acta Cryst. E71, 870–874]. PMID:26594417

  14. Corrosive behavior of chromium carbide-based films formed on steel using a filtered cathodic vacuum arc system

    NASA Astrophysics Data System (ADS)

    Lin, Chun-Chun; Chang, Ku-Ling; Shih, Han C.

    2007-03-01

    The formation of chromium carbide-based hard-coatings on steels using a 90°-bend filtered cathodic vacuum arc (FCVA) has extensive industrial applications; such coatings are free of macroparticles and exhibit excellent characteristics. In this investigation, a working pressure of C 2H 2/Ar was adopted to synthesize amorphous chromium carbide film (a-C:Cr) and crystalline chromium carbide film (cryst-Cr 3C 2) from a Cr target (99.95%) at 500 °C under a substrate voltage of -50 V. The corrosion behavior of a-C:Cr coated on steel (a-C:Cr/steel) and cryst-Cr 3C 2 coated on steel (cryst-Cr 3C 2/steel) were compared in terms of open-circuit potentials (OCP) and polarization resistance ( Rp) in an aerated 3.5 wt% NaCl aqueous solution, as determined by electrochemical impedance spectroscopy (EIS). The XRD results indicated that the transformation of a-C:Cr to cryst-Cr 3C 2 is distinct as the working pressure declines from 1.2 × 10 -2 to 2.9 × 10 -3 Torr. The OCP of a-C:Cr/steel and cryst-Cr 3C 2/steel resemble each other and both assembly are nobler than uncoated steel. The Rp of the coatings exceeds that of the uncoated steel. The SEM observation and the EIS results demonstrate that the cryst-Cr 3C 2/steel more effectively isolates the defects than dose a-C:Cr/steel.

  15. Creativity and Democratic Governance. Adult Learning: A Strategic Choice. Proceedings of the ICAE World Assembly (6th, Ocho Rios, Jamaica, August 9-12, 2001) = Creativite et Gouvernance Democratique. L'apprentissage des Adultes: Un Choix Strategique. Actes de la Assemblee Mondiale du CIEA (6th, Ocho Rios, Jamaique, 9 au 12 aout 2001) = Creatividad y Gobernabilidad Democratica. Educacion de Adultos: Una Eleccion Estrategica. Actas de la Asamblea Mundial del ICAE (6th, Ocho Rios, Jamaica, Agosto 9-12, 2001).

    ERIC Educational Resources Information Center

    Dobson, Stephan, Ed.

    This document contains information from and about a world assembly on creativity and democratic governance in adult learning that was held by the International Council for Adult Education (ICAE) and its partner organizations in the Caribbean. The proceedings begin with English, French, and Spanish translations of the address…

  16. Conical soliton escape into a third dimension of a surface vortex

    NASA Astrophysics Data System (ADS)

    Radzihovsky, Leo; Zhang, Quan

    2009-04-01

    We present an exact three-dimensional solitonic solution to a sine-Gordon-type Euler-Lagrange equation that describes a configuration of a three-dimensional vector field n̂ constrained to a surface p -vortex, with a prescribed polar tilt angle on a planar substrate and escaping into the third dimension in the bulk. The solution is relevant to characterization of a schlieren texture in nematic liquid-crystal films with tangential (in-plane) substrate alignment. The solution is identical to a section of a point defect discovered many years ago by Saupe [Mol. Cryst. Liq. Cryst. 21, 211 (1973)], when latter is restricted to a surface.

  17. Conical soliton escape into a third dimension of a surface vortex.

    PubMed

    Radzihovsky, Leo; Zhang, Quan

    2009-04-01

    We present an exact three-dimensional solitonic solution to a sine-Gordon-type Euler-Lagrange equation that describes a configuration of a three-dimensional vector field n constrained to a surface p-vortex, with a prescribed polar tilt angle on a planar substrate and escaping into the third dimension in the bulk. The solution is relevant to characterization of a schlieren texture in nematic liquid-crystal films with tangential (in-plane) substrate alignment. The solution is identical to a section of a point defect discovered many years ago by Saupe [Mol. Cryst. Liq. Cryst. 21, 211 (1973)], when latter is restricted to a surface. PMID:19518245

  18. Leading the Charge: Governors, Higher Education and Accountability

    ERIC Educational Resources Information Center

    American Council of Trustees and Alumni, 2014

    2014-01-01

    With this new tool, ACTA [American Council of Trustees and Alumni] is working to expand its outreach to governors nationwide on behalf of higher education reform, focusing on key issues of quality, cost, and accountability. ACTA has worked with governors and education leaders from across the country, and that experience has proven that innovative…

  19. The Vanishing Shakespeare: A Report by the American Council of Trustees and Alumni

    ERIC Educational Resources Information Center

    Neal, Anne D.; Mitchell, Charles

    2007-01-01

    As this report goes to press, the nation's capital is in the midst of a six-moth, city-wide celebration of William Shakespeare. With this celebration as a backdrop, the American Council of Trustees and Alumni (ACTA) researched how Shakespeare fits into English curricula at 70 of the nation's leading colleges and universities. ACTA surveyed English…

  20. Genetics Home Reference: paramyotonia congenita

    MedlinePlus

    ... impact of permanent muscle weakness on quality of life in periodic paralysis: a survey of 66 patients. Acta Myol. 2012 Oct;31(2):126-33. Citation on PubMed or Free article on PubMed Central Finsterer J. Primary periodic paralyses. Acta Neurol Scand. 2008 Mar;117(3):145-58. Epub 2007 Nov 20. ...

  1. Spectroscopic characterisation of biological vaterite: relations to synthetic and geological vaterites

    NASA Astrophysics Data System (ADS)

    Jacob, D. E.; Wehrmeister, U.; Soldati, A. L.; Hofmeister, W.

    2009-04-01

    band ?1 into three distinct bands, activation and splitting of ?2 and splitting of both, ?3 and ?4 into six distinct Raman bands. FWHMs of the lattice modes are large (8 cm-1- 44 cm-1) compared to those of aragonite, implying that the structure is not well ordered and possibly affected by stacking faults, layer shifts or syntactic intergrowth; irregularities that further complicate the crystal structure determination. Correlation of Mg-contents in vaterite areas in freshwater cultured pearls with Raman spectra obtained at the same spots show that the FWHMs are influenced by the magnesium content. Similarly, the spectra for the vaterite samples synthesized with differing Mg contents show successively increasing FWHM with increasing magnesium content both for the lattice modes and the ?1 - symmetric stretching mode. Wehrmeister et al., 2007. J. Gemmology; 31: 269-276, Falini et al., 2005. Eur. J. Inorg. Chem. 2005(1): 162 -167, Meyer, H. 1969. Angew. Chem. 21: 678-679, Kamhi, S., 1963. Acta Cryst. (1963).16: 770 - 772, Meyer, H., 1969. Z. Kristallographie 128: 183 - 212, Lippmann, F., 1973. New York, Springer, Soldati et al., 2008. Min. Mag. 72: 577- 590, Jacob et al., 2008. Geochim. Cosmochim. Acta 72: 5401- 5415, Loges et al., 2006. Langmuir 22: 3073-3080.

  2. Arsenic Sorption on TiO2 Nanoparticles: Size And Crystallinity Effects

    EPA Science Inventory

    Single solute As (III) and As (V) sorption on nano-sized amorphous and crystalline TiO2 was investigated to determine: size and crystallinity effects on arsenic sorption capacities, possible As (III) oxidation, and the nature of surface complexes. Amorphous and cryst...

  3. Silver catalysts in the partial oxidation of methanol to formaldehyde

    SciTech Connect

    Devochkin, A.N.; Pestryakov, A.N.; Kurina, L.N.; Sakharov, A.A.

    1992-07-20

    A comparative study of the catalytic activity of supported (Ag/pumice, LNKh-M) and bulk (Ag{sub cryst}, SD, KS) catalysts for methanol oxidation was carried out. The effect of technological parameters on the partial oxidation of methanol was studied. The optimum conditions for conducting the process on the catalysts studied were determined. 5 refs., 1 tab.

  4. Properties of thermoplastic starch and TPS/polycaprolactone blend reinforced with sisal whiskers using extrusion processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sisal whiskers (SW) were prepared by acid hydrolysis for subsequent evaluation as reinforcing material for biodegradable matrices of thermoplastic starch (TPS) and TPS/polycaprolactone (TPS/PCL) blends. The acid hydrolyzed SW had dimensions of 5±2 nm in diameter and 210±60 nm in length and 78% cryst...

  5. 75 FR 6740 - Self-Regulatory Organizations; NYSE Arca, Inc.; Notice of Filing and Immediate Effectiveness of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-10

    ... Act Release No. 60711 (September 23, 2009), 74 FR 49419 (September 28, 2009) (order approving SR.... 190 BCRX BioCryst Pharmaceuticals Inc. 158 PARD Poniard Pharmaceuticals Inc. 218 BK Bank of New York.... 148 XTO XTO Energy Inc. 213 JWN Nordstrom Inc. 130 YRCW YRC Worldwide Inc. 137 KFT Kraft Foods Inc....

  6. 75 FR 6756 - Self-Regulatory Organizations; NYSE Arca, Inc.; Notice of Filing and Immediate Effectiveness of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-10

    ... Act Release No. 60711 (September 23, 2009), 74 FR 49419 (September 28, 2009) (order approving SR... Occidental Petroleum Corp. 190 BCRX BioCryst 158 PARD Poniard Pharmaceuticals Pharmaceuticals Inc. Inc. 218........ 130 YRCW YRC Worldwide Inc. 137 KFT Kraft Foods Inc... 2. Statutory Basis The Exchange believes...

  7. Skeletal muscle α-actin diseases (actinopathies): pathology and mechanisms.

    PubMed

    Nowak, Kristen J; Ravenscroft, Gianina; Laing, Nigel G

    2013-01-01

    Mutations in the skeletal muscle α-actin gene (ACTA1) cause a range of congenital myopathies characterised by muscle weakness and specific skeletal muscle structural lesions. Actin accumulations, nemaline and intranuclear bodies, fibre-type disproportion, cores, caps, dystrophic features and zebra bodies have all been seen in biopsies from patients with ACTA1 disease, with patients frequently presenting with multiple pathologies. Therefore increasingly it is considered that these entities may represent a continuum of structural abnormalities arising due to ACTA1 mutations. Recently an ACTA1 mutation has also been associated with a hypertonic clinical presentation with nemaline bodies. Whilst multiple genes are known to cause many of the pathologies associated with ACTA1 mutations, to date actin aggregates, intranuclear rods and zebra bodies have solely been attributed to ACTA1 mutations. Approximately 200 different ACTA1 mutations have been identified, with 90 % resulting in dominant disease and 10 % resulting in recessive disease. Despite extensive research into normal actin function and the functional consequences of ACTA1 mutations in cell culture, animal models and patient tissue, the mechanisms underlying muscle weakness and the formation of structural lesions remains largely unknown. Whilst precise mechanisms are being grappled with, headway is being made in terms of developing therapeutics for ACTA1 disease, with gene therapy (specifically reducing the proportion of mutant skeletal muscle α-actin protein) and pharmacological agents showing promising results in animal models and patient muscle. The use of small molecules to sensitise the contractile apparatus to Ca(2+) is a promising therapeutic for patients with various neuromuscular disorders, including ACTA1 disease. PMID:22825594

  8. High circulating activin A level is associated with tumor progression and predicts poor prognosis in lung adenocarcinoma

    PubMed Central

    Hoda, Mir Alireza; Rozsas, Anita; Lang, Elisabeth; Klikovits, Thomas; Lohinai, Zoltan; Torok, Szilvia; Berta, Judit; Bendek, Matyas; Berger, Walter; Hegedus, Balazs; Klepetko, Walter; Renyi-Vamos, Ferenc; Grusch, Michael; Dome, Balazs; Laszlo, Viktoria

    2016-01-01

    Activin A (ActA)/follistatin (FST) signaling has been shown to be deregulated in different tumor types including lung adenocarcinoma (LADC). Here, we report that serum ActA protein levels are significantly elevated in LADC patients (n=64) as compared to controls (n=46, p=0.015). ActA levels also correlated with more advanced disease stage (p<0.0001) and T (p=0.0035) and N (p=0.0002) factors. M1 patients had significantly higher ActA levels than M0 patients (p<0.001). High serum ActA level was associated with poor overall survival (p<0.0001) and was confirmed as an independent prognostic factor (p=0.004). Serum FST levels were increased only in female LADC patients (vs. female controls, p=0.031). Two out of five LADC cell lines secreted biologically active ActA, while FST was produced in all of them. Transcripts of both type I and II ActA receptors were detected in all five LADC cell lines. In conclusion, our study does not only suggest that measuring blood ActA levels in LADC patients might improve the prediction of prognosis, but also indicates that this parameter might be a novel non-invasive biomarker for identifying LADC patients with organ metastases. PMID:26950277

  9. Genetics Home Reference: glucose-galactose malabsorption

    MedlinePlus

    ... mutations in SGLT1 cause glucose-galactose malabsorption by trafficking defects. Biochim Biophys Acta. 1999 Feb 24;1453( ... Accessibility FOIA Viewers & Players U.S. Department of Health & Human Services National Institutes of Health National Library of ...

  10. USING BIOMONITORING DATA TO INFORM EXPOSURE ASSESSMENT IN CHILDREN

    EPA Science Inventory

    Discussing the challenges associated with estimating and interpreting toxicant exposures and health risks from biomonitoring data. Extended abstract will also be translated in Spanish and published in Acta Toxicologica Argentina.

  11. 76 FR 6683 - Information Related to Risks and Benefits of Powdered Gloves; Request for Comments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-07

    ..., 2003. 2. Malinger, G., S. Ginath, L. Zeidel, et al., ``Starch Peritonitis Outbreak After Introduction of a New Brand of Starch Powdered Latex Gloves,'' Acta Obstetricia et Gynecologica Scandinavica,...

  12. Bedside calculation of hemodynamic parameters with a hand held programmable calculator. Part II: Programs for hemodynamic and oxygen transport parameters computation.

    PubMed

    Laurent, M

    1980-01-01

    Two programs calculating oxygen transport parameters and hemodynamic values respectively are described. They may be used indifferently with HP 67 or HP 97 Hewlett Packard calculators. (Acta anaesth. belg., 1980, 31, 53-59).

  13. Genetics Home Reference: myosin storage myopathy

    MedlinePlus

    ... proteins accumulate in type I skeletal muscle fibers, forming the protein clumps characteristic of the disorder. It ... Epub 2007 Mar 2. Citation on PubMed Tajsharghi H, Oldfors A. Myosinopathies: pathology and mechanisms. Acta Neuropathol. ...

  14. VISIÓN GENERAL DE LA EVALUACIÓN DEL RIESGO EN SALUD INFANTIL EMPLEANDO UN ENFOQUE POR ETAPAS DE DESARROLLO (American translation is: Overview of a Life Stage Approach to Children's Health Risk Assessment)

    EPA Science Inventory

    Discussing the challenges associated with estimating and interpreting toxicant exposures and health risks from biomonitoring data. This extended abstract was translated in Spanish and published in Acta Toxicologica Argentina.

  15. Uso de los Datos de Biomonitoreo para Informar sobre la Evaluacion Infantil (American translation is: USING BIOMONITORING DATA TO INFORM EXPOSURE ASSESSMENT IN CHILDREN)

    EPA Science Inventory

    Discussing the challenges associated with estimating and interpreting toxicant exposures and health risks from biomonitoring data. This extended abstract was translated in Spanish and published in Acta Toxicologica Argentina.

  16. Activin A accelerates the progression of fetal oocytes throughout meiosis and early oogenesis in the mouse.

    PubMed

    Liang, Gui-Jin; Zhang, Xi-Feng; Wang, Jun-Jie; Sun, Yuan-Chao; Sun, Xiao-Feng; Cheng, Shun-Feng; Li, Lan; De Felici, Massimo; Shen, Wei

    2015-10-15

    Activins can exert several roles in ovary development. However, little is known about their involvement in early mammalian oogenesis. In this study, we reported that activin receptors (including ActRIA, ActRIB, ActRIIA, and ActRIIB) are expressed throughout the development of the mouse ovaries from 12.5 days postcoitum (dpc) to 21 days postparturition (dpp). Moreover, we found that in vitro, the addition of activin A (ActA) to the culture medium of 12.5 dpc ovarian tissues accelerated the progression of oocytes throughout meiotic prophase I stages. This result was reproduced in vivo following administration of ActA to pregnant mice. The in vitro effect of ActA was associated with increased expression of premeiotic and meiotic genes (including Dazl, Spo11, Stra8, Scp3, and Rec8) in the ovarian tissues. Mechanistically, ActA-dependent SMAD3 signaling modulated the expression of members of the retinoic acid (RA) system, including the RA degradation CYP26B1 enzyme and the RA receptors. Finally, ActA promoted the survival and growth of fetal and early postnatal oocytes and primordial follicle assembly both in vitro and in vivo. In conclusion, the present study identifies new roles of ActA in early oogenesis and suggested that ActA and RA might cooperate in promoting meiosis in female germ cells.

  17. Irreversible altering of crystalline phase of phase-change Ge-Sb thin films

    SciTech Connect

    Krusin-Elbaum, L.; Shakhvorostov, D.; Cabral, C. Jr.; Raoux, S.; Jordan-Sweet, J. L.

    2010-03-22

    The stability of the crystalline phase of binary phase-change Ge{sub x}Sb{sub 1-x} films is investigated over a wide range of Ge content. From Raman spectroscopy we find the Ge-Sb crystalline structure irreversibly altered after exposure to a laser beam. We show that with increasing beam intensity/temperature Ge agglomerates and precipitates out in the amount growing with x. A simple empirical relation links Ge precipitation temperature T{sub Ge}{sup p} to the rate of change dT{sub cryst}/dx of crystallization, with the precipitation easiest on the mid-range x plateau, where T{sub cryst} is nearly constant. Our findings point to a preferable 15% < or approx. x < 50% window, that may achieve the desired cycling/archival properties of a phase-change cell.

  18. Crystallographic data processing for free-electron laser sources

    SciTech Connect

    White, Thomas A. Barty, Anton; Stellato, Francesco; Holton, James M.; Kirian, Richard A.; Zatsepin, Nadia A.; Chapman, Henry N.

    2013-07-01

    A processing pipeline for diffraction data acquired using the ‘serial crystallography’ methodology with a free-electron laser source is described with reference to the crystallographic analysis suite CrystFEL and the pre-processing program Cheetah. A processing pipeline for diffraction data acquired using the ‘serial crystallography’ methodology with a free-electron laser source is described with reference to the crystallographic analysis suite CrystFEL and the pre-processing program Cheetah. A detailed analysis of the nature and impact of indexing ambiguities is presented. Simulations of the Monte Carlo integration scheme, which accounts for the partially recorded nature of the diffraction intensities, are presented and show that the integration of partial reflections could be made to converge more quickly if the bandwidth of the X-rays were to be increased by a small amount or if a slight convergence angle were introduced into the incident beam.

  19. Serial femtosecond crystallography datasets from G protein-coupled receptors.

    PubMed

    White, Thomas A; Barty, Anton; Liu, Wei; Ishchenko, Andrii; Zhang, Haitao; Gati, Cornelius; Zatsepin, Nadia A; Basu, Shibom; Oberthür, Dominik; Metz, Markus; Beyerlein, Kenneth R; Yoon, Chun Hong; Yefanov, Oleksandr M; James, Daniel; Wang, Dingjie; Messerschmidt, Marc; Koglin, Jason E; Boutet, Sébastien; Weierstall, Uwe; Cherezov, Vadim

    2016-08-01

    We describe the deposition of four datasets consisting of X-ray diffraction images acquired using serial femtosecond crystallography experiments on microcrystals of human G protein-coupled receptors, grown and delivered in lipidic cubic phase, at the Linac Coherent Light Source. The receptors are: the human serotonin receptor 2B in complex with an agonist ergotamine, the human δ-opioid receptor in complex with a bi-functional peptide ligand DIPP-NH2, the human smoothened receptor in complex with an antagonist cyclopamine, and finally the human angiotensin II type 1 receptor in complex with the selective antagonist ZD7155. All four datasets have been deposited, with minimal processing, in an HDF5-based file format, which can be used directly for crystallographic processing with CrystFEL or other software. We have provided processing scripts and supporting files for recent versions of CrystFEL, which can be used to validate the data.

  20. Serial femtosecond crystallography datasets from G protein-coupled receptors

    PubMed Central

    White, Thomas A.; Barty, Anton; Liu, Wei; Ishchenko, Andrii; Zhang, Haitao; Gati, Cornelius; Zatsepin, Nadia A.; Basu, Shibom; Oberthür, Dominik; Metz, Markus; Beyerlein, Kenneth R.; Yoon, Chun Hong; Yefanov, Oleksandr M.; James, Daniel; Wang, Dingjie; Messerschmidt, Marc; Koglin, Jason E.; Boutet, Sébastien; Weierstall, Uwe; Cherezov, Vadim

    2016-01-01

    We describe the deposition of four datasets consisting of X-ray diffraction images acquired using serial femtosecond crystallography experiments on microcrystals of human G protein-coupled receptors, grown and delivered in lipidic cubic phase, at the Linac Coherent Light Source. The receptors are: the human serotonin receptor 2B in complex with an agonist ergotamine, the human δ-opioid receptor in complex with a bi-functional peptide ligand DIPP-NH2, the human smoothened receptor in complex with an antagonist cyclopamine, and finally the human angiotensin II type 1 receptor in complex with the selective antagonist ZD7155. All four datasets have been deposited, with minimal processing, in an HDF5-based file format, which can be used directly for crystallographic processing with CrystFEL or other software. We have provided processing scripts and supporting files for recent versions of CrystFEL, which can be used to validate the data. PMID:27479354

  1. Serial femtosecond crystallography datasets from G protein-coupled receptors.

    PubMed

    White, Thomas A; Barty, Anton; Liu, Wei; Ishchenko, Andrii; Zhang, Haitao; Gati, Cornelius; Zatsepin, Nadia A; Basu, Shibom; Oberthür, Dominik; Metz, Markus; Beyerlein, Kenneth R; Yoon, Chun Hong; Yefanov, Oleksandr M; James, Daniel; Wang, Dingjie; Messerschmidt, Marc; Koglin, Jason E; Boutet, Sébastien; Weierstall, Uwe; Cherezov, Vadim

    2016-01-01

    We describe the deposition of four datasets consisting of X-ray diffraction images acquired using serial femtosecond crystallography experiments on microcrystals of human G protein-coupled receptors, grown and delivered in lipidic cubic phase, at the Linac Coherent Light Source. The receptors are: the human serotonin receptor 2B in complex with an agonist ergotamine, the human δ-opioid receptor in complex with a bi-functional peptide ligand DIPP-NH2, the human smoothened receptor in complex with an antagonist cyclopamine, and finally the human angiotensin II type 1 receptor in complex with the selective antagonist ZD7155. All four datasets have been deposited, with minimal processing, in an HDF5-based file format, which can be used directly for crystallographic processing with CrystFEL or other software. We have provided processing scripts and supporting files for recent versions of CrystFEL, which can be used to validate the data. PMID:27479354

  2. Serial crystallographic analysis of protein isomorphous replacement data from a mixture of native and derivative microcrystals.

    PubMed

    Zhang, Tao; Yao, Deqiang; Wang, Jiawei; Gu, Yuanxin; Fan, Haifu

    2015-12-01

    A post-experimental identification/purification procedure similar to that described in Zhang et al. [(2015), IUCrJ, 2, 322-326] has been proposed for use in the treatment of multiphase protein serial crystallography (SX) diffraction snapshots. As a proof of concept, the procedure was tested using theoretical serial femtosecond crystallography (SFX) data from a mixture containing native and derivatized crystals of a protein. Two known proteins were taken as examples. Multiphase diffraction snapshots were subjected to two rounds of indexing using the program CrystFEL [White et al. (2012). J. Appl. Cryst. 45, 335-341]. In the first round, an ab initio indexing was performed to derive a set of approximate primitive unit-cell parameters, which are roughly the average of those from the native protein and the derivative. These parameters were then used in a second round of indexing as input to CrystFEL. The results were then used to separate the diffraction snapshots into two subsets corresponding to the native and the derivative. For each test sample, integration of the two subsets of snapshots separately led to two sets of three-dimensional diffraction intensities, one belonging to the native and the other to the derivative. Based on these two sets of intensities, a conventional single isomorphous replacement (SIR) procedure solved the structure easily. PMID:26627658

  3. Termochemical Models For Slags and Silicate Melts, Review and Perspectives

    NASA Astrophysics Data System (ADS)

    Ottonello, G.

    R.O. (1983) Contrib. Mineral. Petrol., 84, 107-145. [3] Papale P. (1997) Contrib. Mineral. Petrol., 126, 237-251. [4] Papale P. (1999) Amer. Mineral., 84, 477-492. [5] Nuccio P.M. and Paonita A. (2999) Earth Planet. Sci. Letters., 183, 499-512. [6] Berman R.G. and Brown T.H. (1984) Geochim. Cosmochim. Acta, 48, 661-678. [7] Lin P.L. and Pelton A.D. (1979) Metall. Trans. B., 10B, 667-675. [8] Pelton A.D. and Blander M. (1986) Metall. Trans. B., 17B, 805-15. [9] Kapoor M.L., Mehrotre G.M. and Frohberg M.G. (1975) Proc. Aust. Inst. Mining Metall., 254, 11. [10] Kapoor M.L., Frohberg G.M. (1971) Proc. Symp. "Chemical Metallurgy of Iron and Steel" Sheffield. [11] Taylor J.R. and Dinsdale A.T. (1990] CALPHAD, 14, 71-88. [12] Sastri P. and Lahiri A.K. (1986) Metall. Trans. B., 17B, 105-110. [13] Bjorkman B. (1985) CALPHAD, 9, 271-282. [14] Hastie J.W., Horton W.S., Plante E.R. and Bonnell D.W. (1982) High Temp. High Press., 14, 669-679. [15] Goel R.P., Kellogg H.H. and Larrain J.M. (1980) Metall. Trans. B., 11B, 107-117. [16] Hillert M., Sundman B. and Wang X. (1990) Metall. Trans. B., 21B, 303-12. [17] Hoch M. and Arpshofen I. (1984) Zeits. fur Metallkde., 75, 23-29. [18] Masson C.R. (1965) Proc. Roy. Soc. London, A287, 201-221. [19] Masson C.R. (1968) J. Amer. Ceram. Soc., 51, 134-143. [20] Masson C.R. (1972) Jour. Iron Steel Inst., 210, 89-96. [21] Toop G.W. and Samis C.S. (1962) Can. Met. Quart., 1, 129-52. [22] Toop G.W. and Samis C.S. (1962) Trans. AIME, 224, 878-87. [23] Ottonello G., Moretti R., Marini L. and Vetuschi Zuccolini M. (2000) Chem. Geol., 174, 157-179. [24] Ottonello G. (2001) J. Non-Cryst. Solids, 282, 72-85. [25] Moretti R. and Ottonello G. (2002) , Metall. Trans. (submitted).

  4. Modulating myosin restores muscle function in a mouse model of nemaline myopathy

    PubMed Central

    Lindqvist, Johan; Levy, Yotam; Pati‐Alam, Alisha; Hardeman, Edna C.; Gregorevic, Paul

    2016-01-01

    Objective Nemaline myopathy, one of the most common congenital myopathies, is associated with mutations in various genes including ACTA1. This disease is also characterized by various forms/degrees of muscle weakness, with most cases being severe and resulting in death in infancy. Recent findings have provided valuable insight into the underlying pathophysiological mechanisms. Mutations in ACTA1 directly disrupt binding interactions between actin and myosin, and consequently the intrinsic force‐generating capacity of muscle fibers. ACTA1 mutations are also associated with variations in myofiber size, the mechanisms of which have been unclear. In the present study, we sought to test the hypotheses that the compromised functional and morphological attributes of skeletal muscles bearing ACTA1 mutations (1) would be directly due to the inefficient actomyosin complex and (2) could be restored by manipulating myosin expression. Methods We used a knockin mouse model expressing the ACTA1 His40Tyr actin mutation found in human patients. We then performed in vivo intramuscular injections of recombinant adeno‐associated viral vectors harboring a myosin transgene known to facilitate muscle contraction. Results We observed that in the presence of the transgene, the intrinsic force‐generating capacity was restored and myofiber size was normal. Interpretation This demonstrates a direct link between disrupted attachment of myosin molecules to actin monomers and muscle fiber atrophy. These data also suggest that further therapeutic interventions should primarily target myosin dysfunction to alleviate the pathology of ACTA1‐related nemaline myopathy. Ann Neurol 2016;79:717–725 PMID:26891371

  5. Actin nemaline myopathy mouse reproduces disease, suggests other actin disease phenotypes and provides cautionary note on muscle transgene expression.

    PubMed

    Ravenscroft, Gianina; Jackaman, Connie; Sewry, Caroline A; McNamara, Elyshia; Squire, Sarah E; Potter, Allyson C; Papadimitriou, John; Griffiths, Lisa M; Bakker, Anthony J; Davies, Kay E; Laing, Nigel G; Nowak, Kristen J

    2011-01-01

    Mutations in the skeletal muscle α-actin gene (ACTA1) cause congenital myopathies including nemaline myopathy, actin aggregate myopathy and rod-core disease. The majority of patients with ACTA1 mutations have severe hypotonia and do not survive beyond the age of one. A transgenic mouse model was generated expressing an autosomal dominant mutant (D286G) of ACTA1 (identified in a severe nemaline myopathy patient) fused with EGFP. Nemaline bodies were observed in multiple skeletal muscles, with serial sections showing these correlated to aggregates of the mutant skeletal muscle α-actin-EGFP. Isolated extensor digitorum longus and soleus muscles were significantly weaker than wild-type (WT) muscle at 4 weeks of age, coinciding with the peak in structural lesions. These 4 week-old mice were ~30% less active on voluntary running wheels than WT mice. The α-actin-EGFP protein clearly demonstrated that the transgene was expressed equally in all myosin heavy chain (MHC) fibre types during the early postnatal period, but subsequently became largely confined to MHCIIB fibres. Ringbinden fibres, internal nuclei and myofibrillar myopathy pathologies, not typical features in nemaline myopathy or patients with ACTA1 mutations, were frequently observed. Ringbinden were found in fast fibre predominant muscles of adult mice and were exclusively MHCIIB-positive fibres. Thus, this mouse model presents a reliable model for the investigation of the pathobiology of nemaline body formation and muscle weakness and for evaluation of potential therapeutic interventions. The occurrence of core-like regions, internal nuclei and ringbinden will allow analysis of the mechanisms underlying these lesions. The occurrence of ringbinden and features of myofibrillar myopathy in this mouse model of ACTA1 disease suggests that patients with these pathologies and no genetic explanation should be screened for ACTA1 mutations. PMID:22174871

  6. Exogenous supplementation of Activin A enhances germ cell differentiation of human embryonic stem cells.

    PubMed

    Duggal, Galbha; Heindryckx, Björn; Warrier, Sharat; Taelman, Jasin; Van der Jeught, Margot; Deforce, Dieter; Chuva de Sousa Lopes, Susana; De Sutter, Petra

    2015-05-01

    Human embryonic stem cells (hESCs) derived in the presence of Activin A (ActA) demonstrate an increased differentiation propensity toward the germ cell lineage. In addition, mouse epiblast stem cells and mouse epiblast-like cells are poised toward germ cell differentiation and are derived in the presence of ActA. We therefore investigated whether supplementation with ActA enhances in vitro hESC differentiation toward germ cell lineage. ActA up-regulated early primordial germ cell (PGC) genes STELLA/DPPA3 (developmental pluripotency associated 3) and tyrosine kinase receptor cKIT in both ActA-derived and standard-derived hESCs indicating its role in priming hESCs toward the PGC lineage. Indeed, ActA plus bone morphogenic protein 4 (BMP4) strongly increased germ cell differentiation potential of hESCs based on the high expression of late PGC markers DAZL (deleted in azoospermia-like) and VASA/DDX4 (DEAD-box polypeptide 4) at mRNA and protein level. Hence, the combination of ActA with BMP4 provides an additional boost for hESCs to develop into postmigratory germ cells. Together with increased VASA expression in the presence of ActA and BMP4, we also observed up-regulation of endoderm-specific genes GATA4 (GATA binding protein 4) and GATA6. Finally, we were able to further mature these in vitro-derived PGC-like cells (PGCLCs) by culturing them in in vitro maturation (IVM) medium, resulting in the formation of germ cell-like clusters and induction of meiotic gene expression. In conclusion, we demonstrate for the first time a synergism between ActA and BMP4 in facilitating germ cell-directed differentiation of hESCs, which is enhanced by extended culture in IVM medium, as shown by cytoplasmic VASA-expressing PGCLCs. We propose a novel relationship between the endoderm and germ cell lineage during hESC differentiation.

  7. An In Vivo Selection Identifies Listeria monocytogenes Genes Required to Sense the Intracellular Environment and Activate Virulence Factor Expression.

    PubMed

    Reniere, Michelle L; Whiteley, Aaron T; Portnoy, Daniel A

    2016-07-01

    Listeria monocytogenes is an environmental saprophyte and facultative intracellular bacterial pathogen with a well-defined life-cycle that involves escape from a phagosome, rapid cytosolic growth, and ActA-dependent cell-to-cell spread, all of which are dependent on the master transcriptional regulator PrfA. The environmental cues that lead to temporal and spatial control of L. monocytogenes virulence gene expression are poorly understood. In this study, we took advantage of the robust up-regulation of ActA that occurs intracellularly and expressed Cre recombinase from the actA promoter and 5' untranslated region in a strain in which loxP sites flanked essential genes, so that activation of actA led to bacterial death. Upon screening for transposon mutants that survived intracellularly, six genes were identified as necessary for ActA expression. Strikingly, most of the genes, including gshF, spxA1, yjbH, and ohrA, are predicted to play important roles in bacterial redox regulation. The mutants identified in the genetic selection fell into three broad categories: (1) those that failed to reach the cytosolic compartment; (2) mutants that entered the cytosol, but failed to activate the master virulence regulator PrfA; and (3) mutants that entered the cytosol and activated transcription of actA, but failed to synthesize it. The identification of mutants defective in vacuolar escape suggests that up-regulation of ActA occurs in the host cytosol and not the vacuole. Moreover, these results provide evidence for two non-redundant cytosolic cues; the first results in allosteric activation of PrfA via increased glutathione levels and transcriptional activation of actA while the second results in translational activation of actA and requires yjbH. Although the precise host cues have not yet been identified, we suggest that intracellular redox stress occurs as a consequence of both host and pathogen remodeling their metabolism upon infection. PMID:27414028

  8. An In Vivo Selection Identifies Listeria monocytogenes Genes Required to Sense the Intracellular Environment and Activate Virulence Factor Expression

    PubMed Central

    Portnoy, Daniel A.

    2016-01-01

    Listeria monocytogenes is an environmental saprophyte and facultative intracellular bacterial pathogen with a well-defined life-cycle that involves escape from a phagosome, rapid cytosolic growth, and ActA-dependent cell-to-cell spread, all of which are dependent on the master transcriptional regulator PrfA. The environmental cues that lead to temporal and spatial control of L. monocytogenes virulence gene expression are poorly understood. In this study, we took advantage of the robust up-regulation of ActA that occurs intracellularly and expressed Cre recombinase from the actA promoter and 5’ untranslated region in a strain in which loxP sites flanked essential genes, so that activation of actA led to bacterial death. Upon screening for transposon mutants that survived intracellularly, six genes were identified as necessary for ActA expression. Strikingly, most of the genes, including gshF, spxA1, yjbH, and ohrA, are predicted to play important roles in bacterial redox regulation. The mutants identified in the genetic selection fell into three broad categories: (1) those that failed to reach the cytosolic compartment; (2) mutants that entered the cytosol, but failed to activate the master virulence regulator PrfA; and (3) mutants that entered the cytosol and activated transcription of actA, but failed to synthesize it. The identification of mutants defective in vacuolar escape suggests that up-regulation of ActA occurs in the host cytosol and not the vacuole. Moreover, these results provide evidence for two non-redundant cytosolic cues; the first results in allosteric activation of PrfA via increased glutathione levels and transcriptional activation of actA while the second results in translational activation of actA and requires yjbH. Although the precise host cues have not yet been identified, we suggest that intracellular redox stress occurs as a consequence of both host and pathogen remodeling their metabolism upon infection. PMID:27414028

  9. Scientometric Analysis of the Journals of the Academy of Medical Sciences in Bosnia and Herzegovina

    PubMed Central

    Masic, Izet; Begic, Edin; Zunic, Lejla

    2016-01-01

    Introduction: Currently in Bosnia and Herzegovina there are 25 journals in the field of biomedicine, 6 of them are indexed in Medline/PubMed base (Medical Archives, Materia Socio-Medica, Acta Informatica Medica, Acta Medica Academica, Bosnian Journal of Basic Medical Sciences (BJBMS) and Medical Glasnik), and one (BJBMS) is indexed in Science Citation Index Expanded (SCIE)/Web of Science base. Aim: The aim of this study was to show the scope of work of the journals that were published by Academy of Medical Sciences of Bosnia and Herzegovina - Medical Archives, Materia Socio-Medica and Acta Informatica Medica. Material and Methods: The research presents a meta-analysis of three journals, or their issues, during the calendar year 2015 (retrospective and descriptive character). Results: During 2015 calendar year a total of 286 articles were published (in Medical Archives 104 (36.3%), in Materia Socio-Medica 99 (34.6%), and in Acta Informatica Medica 83 (29%)). Original articles are present in the highest number in all three journals (in Medical Archives 80.7%, in Materia Socio Medica 77.7%, and in Acta Informatica Medica 68.6%). In Medical Archives, 90.3% of the articles were related to the field of clinical medicine. In Materia Socio-Medica, the domain of clinical medicine and public health was the most represented. Preclinical areas are most frequent in Acta Informatica Medica. The period of 50-60 days for a decision on the admission of article is most common in all three journals, with trend of shortening of that period. Articles came from 19 countries, mostly from Bosnia and Herzegovina, then from Iran, Kosovo, Saudi Arabia and Greece. Conclusion: In Medical Archives original articles in the field of clinical medicine (usually internal and surgical disciplines) are most often present, and that is the case in last four years. The number of articles in Materia Socio-Medica and Acta Informatica Medica is growing from year to year. In Materia Socio-Medica there is a

  10. Quantification and handling of nonlinearity in Raman micro-spectrometry of pharmaceuticals.

    PubMed

    Nagy, Brigitta; Farkas, Attila; Balogh, Attila; Pataki, Hajnalka; Vajna, Balázs; Nagy, Zsombor K; Marosi, György

    2016-09-01

    This work demonstrates how nonlinearity in Raman spectrometry of pharmaceuticals can be handled and accurate quantification can be achieved by applying certain chemometric methods including variable selection. Such approach proved to be successful even if the component spectra are very similar or spectral intensities of the constituents are strongly different. The relevant examples are: blends of two crystalline forms of carvedilol ("CRYST-PM" blend) and a three-component pharmaceutical model system ("PHARM-TM" blend). The widely used classical least squares regression (CLS) and partial least squares regression (PLS) quantification methods provided relatively poor root mean squared error of prediction (RMSEP) values: approximately 2-4% and 4-10% for CRYST-PM and PHARM-TM respectively. The residual plots of these models indicated the nonlinearity of the preprocessed data sets. More accurate quantitative results could be achieved with properly applied variable selection methods. It was observed that variable selection methods discarded the most intensive bands while less intensive ones were retained as the most informative spectral ranges. As a result not only the accuracy of concentration determination was enhanced, but the linearity of models was improved as well. This indicated that nonlinearity occurred especially at the intensive spectral bands. Other methods developed for handling nonlinearity were also capable of adapting to the spectral nature of both data sets. The RMSEP could be decreased this way to 1% in CRYST-PM and 3-6% in PHARM-TM. Raman maps with accurate real concentrations could be prepared this way. All quantitative models were compared by the non-parametric sum of ranking differences (SRD) method, which also proved that models based on variable selection or nonlinear methods provide better quantification. PMID:27281579

  11. A survey of chemical information systems

    NASA Technical Reports Server (NTRS)

    Dominick, Wayne D. (Editor); Shaikh, Aneesa Bashir

    1985-01-01

    A survey of the features, functions, and characteristics of a fairly wide variety of chemical information storage and retrieval systems currently in operation is given. The types of systems (together with an identification of the specific systems) addressed within this survey are as follows: patents and bibliographies (Derwent's Patent System; IFI Comprehensive Database; PULSAR); pharmacology and toxicology (Chemfile; PAGODE; CBF; HEEDA; NAPRALERT; MAACS); the chemical information system (CAS Chemical Registry System; SANSS; MSSS; CSEARCH; GINA; NMRLIT; CRYST; XTAL; PDSM; CAISF; RTECS Search System; AQUATOX; WDROP; OHMTADS; MLAB; Chemlab); spectra (OCETH; ASTM); crystals (CRYSRC); and physical properties (DETHERM). Summary characteristics and current trends in chemical information systems development are also examined.

  12. Symmetry considerations in structural phase transitions

    NASA Astrophysics Data System (ADS)

    Perez-Mato, J. M.; Aroyo, M. I.; Orobengoa, D.

    2012-03-01

    The most important symmetry arguments to be considered in the analysis of structural phase transitions are reviewed. A practical approach is used, with the discussion of many examples. In particular, we stress the straightforward application of computer tools freely available in internet to solve these symmetry-related problems. We focus on programs available on the Bilbao Crystallographic Server (www.cryst.ehu.es), but also the use of some programs from the ISOTROPY site (http://stokes.byu.edu/isotropy.html) is discussed.

  13. Development of Guidance for States Transitioning to New Safety Analysis Tools

    ERIC Educational Resources Information Center

    Alluri, Priyanka

    2010-01-01

    With about 125 people dying on US roads each day, the US Department of Transportation heightened the awareness of critical safety issues with the passage of SAFETEA-LU (Safe Accountable Flexible Efficient Transportation Equity Act--A Legacy for Users) legislation in 2005. The legislation required each of the states to develop a Strategic Highway…

  14. Experiences of a local arrangement committee for a large scientific conference

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper is an an invited condensation of a paper that appeared in Acta. Hort. 745: 513-532 last year. It describes the history and organization of the combined meeting of the 90th Annual Meeting of the Potato Association of America, the VI International Solanaceae Conference, and the III Solanace...

  15. Investigating Multitasking in High-Functioning Adolescents with Autism Spectrum Disorders Using the Virtual Errands Task

    ERIC Educational Resources Information Center

    Rajendran, Gnanathusharan; Law, Anna S.; Logie, Robert H.; van der Meulen, Marian; Fraser, Diane; Corley, Martin

    2011-01-01

    Using a modified version of the Virtual Errands Task (VET; McGeorge et al. in "Presence-Teleop Virtual Environ" 10(4):375-383, 2001), we investigated the executive ability of multitasking in 18 high-functioning adolescents with ASD and 18 typically developing adolescents. The VET requires multitasking (Law et al. in "Acta Psychol" 122(1):27-44,…

  16. On the existence of 'L-alanine cadmium bromide'.

    PubMed

    Srinivasan, Bikshandarkoil R

    2013-12-01

    It is argued that the recently reported nonlinear optical crystal L-alanine cadmium bromide, grown by slow solvent evaporation method at room temperature [P. Ilayabarathi, J. Chandrasekaran, Spectrochim. Acta 96A (2012) 684-689] is the well-known L-alanine crystal. The isolation of L-alanine crystal is explained due to fractional crystallization.

  17. Ben van der Veken Honor Issue

    NASA Astrophysics Data System (ADS)

    Durig, James

    2015-02-01

    In acclamation of Ben van der Veken, a former editor of Spectrochimica Acta, many co-authors and friends have submitted papers in his honor. He has collaborated with many scientists from the United States, Russia, England, Scotland as well as some in other countries. His research is known throughout the world.

  18. As Stimulus Tap Turns on, Districts Can't Escape Cuts

    ERIC Educational Resources Information Center

    Samuels, Chrsitina A.

    2009-01-01

    As the first federal stimulus money began flowing to states last week, local school administrators across the nation were crunching numbers to determine just how much relief to expect. Even with the unprecedented federal investment in education under the American Recovery and Reinvestment Act--a total of up to $100 billion for K-12 over two…

  19. Measures of Muscular Strength in U.S. Children and Adolescents, 2012

    MedlinePlus

    ... performance and DXA-derived lean body mass and fat mass in pre-pubertal children. Acta Pædiatr 100(10):1359–67. 2011. Suggested citation Ervin RB, Wang C-Y, Fryar CD, et al. Measures of ...

  20. Education or Reputation? A Look at America's Top-Ranked Liberal Arts Colleges

    ERIC Educational Resources Information Center

    Poliakoff, Michael; Alacbay, Armand

    2014-01-01

    ACTA [American Council of Trustees and Alumni] today released a report that examines the country's most prestigious liberal arts colleges. Despite endowments soaring as high as $1.8 billion, nearly all institutions increased tuition during the Great Recession to finance bloated administrative spending, with many college presidents enjoying…

  1. Bold Leadership Real Reform [Annual Report, 2014

    ERIC Educational Resources Information Center

    American Council of Trustees and Alumni, 2015

    2015-01-01

    Higher education has never been more "front and center"--almost daily we hear about spiraling costs, the lack of academic rigor, and the stifling political correctness on our college campuses. Long before such issues were hot, ACTA [American Council of Trustees and Alumni] was already pointing out these worrisome trends and calling on…

  2. Eventos de Agosto (August Events).

    ERIC Educational Resources Information Center

    Toro, Leonor; Pla, Myrna

    Written in Spanish, this booklet contains brief information on seven August events celebrated by Puerto Ricans: Herbert Hoover's birthdate (August 10); Acta del Seguro Social (Social Security Act, August 14); Julian E. Blanco (August 14), Enmienda 19 Sufragia de la Mujer (Amendment 19, Women's Suffrage, August 26); Benjamin Harrison (August 20);…

  3. Effects of space flights on human allergic status (IgE-mediated sensitivity)

    NASA Astrophysics Data System (ADS)

    Buravkova, L. B.; Rykova, M. P.; Gertsik, Y. G.; Antropova, E. N.

    2007-02-01

    Suppression of the immune system after space flights of different duration has been reported earlier by Konstantinova [Immune system in extreme conditions, Space immunology. B. 59. M. Science 1988. 289p. (in Russian) [4]; Immunoresistance of man in space flight, Acta Astronautica 23 (1991) 123-127 [5

  4. Severe congenital actin related myopathy with myofibrillar myopathy features.

    PubMed

    Selcen, Duygu

    2015-06-01

    Mutations in ACTA1 have been associated with different pathologic findings including nemaline myopathy, intranuclear rod myopathy, actin myopathy, cap myopathy, congenital fiber type disproportion, and core myopathy. Myofibrillar myopathies are morphologically distinct but genetically heterogeneous muscular dystrophies arising from mutations in Z-disk related proteins. We report a 26-month-old boy with significantly delayed motor development requiring mechanical ventilation and tube-feeding since birth. The muscle biopsy displayed typical features of myofibrillar myopathy with abnormal expression of multiple proteins. Whole exome sequencing revealed two-amino-acid duplication in ACTA1. In cell culture system, mutant actin was expressed at ~11% of wild-type, and mutant actin formed pleomorphic cytoplasmic aggregates whereas wild-type actin appeared in filamentous structures. We conclude that mutations in ACTA1 can cause pathologic features consistent with myofibrillar myopathy, and mutations in ACTA1 should be considered in patients with severe congenital hypotonia associated with muscle weakness and features of myofibrillar myopathy. PMID:25913210

  5. Diffusive Insights: On the Disagreement of Christian Bohr and August Krogh at the Centennial of the Seven Little Devils

    ERIC Educational Resources Information Center

    Gjedde, Albert

    2010-01-01

    The year 2010 is the centennial of the publication of the "Seven Little Devils" in the predecessor of "Acta Physiologica". In these seven papers, August and Marie Krogh sought to refute Christian Bohr's theory that oxygen diffusion from the lungs to the circulation is not entirely passive but rather facilitated by a specific cellular activity…

  6. The Cost of Chaos in the Curriculum. Perspectives on Higher Education

    ERIC Educational Resources Information Center

    Capaldi Phillips, Elizabeth D.; Poliakoff, Michael B.

    2015-01-01

    ACTA's report "The Cost of Chaos in the Curriculum" reveals that the vast array of course choices given to college students is a cause of exploding costs and poor academic outcomes. And a bloated undergraduate curriculum is particularly detrimental to the success of students from lower socioeconomic backgrounds. The report documents how…

  7. Increased expression of a plant actin gene during a biotrophic interaction between round-leaved mallow, Malva pusilla, and Colletotrichum gloeosporioides f. sp. malvae.

    PubMed

    Jin, S; Xu, R; Wei, Y; Goodwin, P H

    1999-10-01

    Two actin genes, actA from the hemibiotrophic anthracnose fungus, Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. f. sp. malvae, and act1 from its host, Malva pusilla (Sm.) were cloned from a cDNA library developed from infected host tissue. The actin gene, actA, of C. gloeosporioides f. sp. malvae, which is similar to that of other euascomycetes, appears to be expressed constitutively. The actin gene of M. pusilla is most similar to one of the actin genes of Arabidopsis thaliana that is unique in being responsive to environmental stimuli such as wounding. Expression of actA was used to follow the growth of the fungus in the plant tissue. Low actA expression occurred until 72-96 h after inoculation and then increased rapidly, corresponding with the timing of the shift from slower biotrophic fungal growth to much more rapid necrotrophic growth. In contrast, expression of act1 approximately doubled during the biotrophic phase and then rapidly declined during the necrotrophic phase. Increased host actin expression could be due to host cytoskeleton rearrangement in response to biotrophic infection, and the subsequent decrease in host actin expression could be due to host cell disruption resulting from tissue maceration during necrosis. This is the first report of a host actin gene that can increase in expression during a compatible plant-pathogen interaction.

  8. Nebraska Swims Hard against Testing's Tides

    ERIC Educational Resources Information Center

    Borja, Rhea R.

    2007-01-01

    Sometimes assessments that work in theory fall apart in reality. This article discusses the unique learning-measurement system in Nebraska. Instead of relying on statewide standardized tests to comply with the accountability requirements of the federal No Child Left Behind Act--as is the case in the other 49 states--districts in Nebraska use their…

  9. Prepared in Mind and Resources? A Report on Public Higher Education in South Carolina

    ERIC Educational Resources Information Center

    Alacbay, Armand; Poliakoff, Michael

    2011-01-01

    In 2011, South Carolina Governor Nikki Haley signed into law the South Carolina Higher Education Efficiency and Administrative Policies Act, maintaining the transparency and accountability that lead to increased academic quality and affordability at colleges and universities. It is in this context that ACTA (American Council of Trustees and…

  10. Actin in the oomycetous fungus Phytophthora infestans is the product of several genes.

    PubMed

    Unkles, S E; Moon, R P; Hawkins, A R; Duncan, J M; Kinghorn, J R

    1991-04-01

    Actin (ACT) in Phytophthora infestans is encoded by at least two genes, in contrast to unicellular and other filamentous fungi where there is a single gene. These genes (designated actA and actB) have been isolated from a genomic library of P. infestans. The complete nucleotide sequence of both genes has been determined. Unlike the actin-encoding genes (act) of other filamentous fungi, no introns are obvious in the coding region, a feature shared with the act genes of certain protists. Northern blotting and primer extension studies of the mRNA show that actA and actB are actively transcribed in mycelium, sporangia and germinating cysts but only at a low level in the case of actB. Both genes display bias in their codon usage. This is more extreme in actA. The deduced ACTB protein is strikingly similar to that of the Phytophthora megasperma actin and is more diverged from other actins than ACTA.

  11. Activity Scale.

    ERIC Educational Resources Information Center

    Kerpelman, Larry C.; Weiner, Michael J.

    This twenty-four item scale assesses students' actual and desired political-social activism in terms of physical participation, communication activities, and information-gathering activities. About ten minutes are required to complete the instrument. The scale is divided into two subscales. The first twelve items (ACT-A) question respondents on…

  12. Approaches to Cell Biology Teaching: Mapping the Journey--Concept Maps as Signposts of Developing Knowledge Structures

    ERIC Educational Resources Information Center

    Allen, Deborah; Tanner, Kimberly

    2003-01-01

    An instructor contemplating a course transformation to incorporate a student-centered learning environment may feel faced with what seems like a high-wire balancing act--a constantly renegotiated compromise between students' legitimate needs for structure, well-understood expectations, and good grades and instructors' foreknowledge that the path…

  13. Higher: Setting a Higher Bar for Higher Ed. 2013 Annual Report

    ERIC Educational Resources Information Center

    American Council of Trustees and Alumni, 2014

    2014-01-01

    The American Council of Trustees and Alumni (ACTA) is leading the charge to return "higher" to higher education. We are challenging the status quo to restore academic freedom, academic rigor, and real accountability to higher education. And, we are doing so with an ever-widening network of supporters and partners.

  14. 77 FR 63203 - 50th Anniversary of the Office of the United States Trade Representative

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-16

    ... United States Trade Representative (USTR) continues to play a vital role in advancing trade policy that... Trade Representative By the President of the United States of America A Proclamation On October 11, 1962, President John F. Kennedy signed the Trade Expansion Act--a landmark piece of legislation that established...

  15. Governance for a New Era: A Blueprint for Higher Education Trustees

    ERIC Educational Resources Information Center

    Schmidt, Benno C.

    2014-01-01

    "Governance for a New Era: A Blueprint for Higher Education Governance," is the product of a summit facilitated by ACTA [American Council of Trustees and Alumni] and chaired by Benno Schmidt, City University of New York Board chairman. Signatories to the statement, a diverse group of 22 distinguished national leaders, include college…

  16. Erratum to: Vascular endothelial growth factor induces contralesional corticobulbar plasticity and functional neurological recovery in the ischemic brain.

    PubMed

    Reitmeir, Raluca; Kilic, Ertugrul; Reinboth, Barbara S; Guo, Zeyun; ElAli, Ayman; Zechariah, Anil; Kilic, Ülkan; Hermann, Dirk M

    2015-10-01

    Erratum to: Acta Neuropathol (2012) 123:273–284. DOI 10.1007/s00401‑011‑0914‑z. The authors would like to correct Fig. 3 of the original manuscript, since the image in Fig. 3b does not correspond to a VEGF treated animal. Corrected Fig. 3 is shown below. We apologize for this mistake.

  17. 77 FR 5617 - Alternative Transportation in Parks and Public Lands Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-03

    ..., Efficient Transportation Equity Act--A Legacy for Users of 2005 (SAFETEA-LU) and its extensions, and... expenses for alternative transportation systems in parks and public lands. Federal land management agencies and State, tribal and local governments acting with the consent of a Federal land management...

  18. 78 FR 22026 - Alternative Transportation in Parks and Public Lands Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-12

    ... authorized by Section 3021 of the Safe, Accountable, Flexible, Efficient Transportation Equity Act--A Legacy... lands. Federal land management agencies and State, tribal and local governments acting with the consent of a federal land management agency are eligible recipients. This program was not re-authorized...

  19. Magnus Strandqvist: 50th anniversary of his doctoral thesis.

    PubMed

    Kajanti, M J

    1994-01-01

    This article is dedicated to Magnus Strandqvist's famous doctoral thesis "Studien über die kumulative Wirkung der Röntgenstrahlen bei Fraktionierung. Erfahrungen aus dem Radiumhemmet an 280 Haut- und Lippenkarzinomen" published in Acta Radiologica in 1944. After a short biography of Strandqvist some central points of his work and their influence on future development of modern radiotherapy are presented. PMID:7993639

  20. 78 FR 19009 - Gary Alfred Shearer, M.D.; Decision And Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-28

    ... (2000); Jesus R. Juarez, M.D., 62 FR 14945 (1997); see also Philip E. Kirk, M.D., 48 FR 32887 (1983... proceeding under section 304, 21 U.S.C. 824, of the CSA.'' Zhiwei Lin, 77 FR 18862, 18864 (2012) (citing... Kentucky, not Florida.) \\16\\ See Michael G. Dolin, M.D., 65 FR 5661 (2000); see also Philip E. Kirk,...

  1. Spectral data compression using weighted principal component analysis with consideration of human visual system and light sources

    NASA Astrophysics Data System (ADS)

    Cao, Qian; Wan, Xiaoxia; Li, Junfeng; Liu, Qiang; Liang, Jingxing; Li, Chan

    2016-10-01

    This paper proposed two weight functions based on principal component analysis (PCA) to reserve more colorimetric information in spectral data compression process. One weight function consisted of the CIE XYZ color-matching functions representing the characteristic of the human visual system, while another was made up of the CIE XYZ color-matching functions of human visual system and relative spectral power distribution of the CIE standard illuminant D65. The improvement obtained from the proposed two methods were tested to compress and reconstruct the reflectance spectra of 1600 glossy Munsell color chips and 1950 Natural Color System color chips as well as six multispectral images. The performance was evaluated by the mean values of color difference under the CIE 1931 standard colorimetric observer and the CIE standard illuminant D65 and A. The mean values of root mean square errors between the original and reconstructed spectra were also calculated. The experimental results show that the proposed two methods significantly outperform the standard PCA and another two weighted PCA in the aspects of colorimetric reconstruction accuracy with very slight degradation in spectral reconstruction accuracy. In addition, weight functions with the CIE standard illuminant D65 can improve the colorimetric reconstruction accuracy compared to weight functions without the CIE standard illuminant D65.

  2. Metameric effect between natural teeth and the shade tabs of a shade guide.

    PubMed

    Corcodel, Nicoleta; Helling, Stephan; Rammelsberg, Peter; Hassel, Alexander J

    2010-06-01

    The objective of this study was to evaluate metameric effects, that is, the dependence of the colours of teeth and shade tabs on the illuminant used. The colours of 49 teeth of 37 participants and of the corresponding shade tabs of the 3D-Master (VITA Zahnfabrik; colour match DeltaE(ab)< 2) were measured using an intra-oral spectrophotometer (VITA Easyshade). Spectral reflectance data (from 400 to 700 nm) were recorded. Commission Internationale de l'Eclairage (CIE) L*a*b* values were calculated for D65 (reference daylight), A (incandescent light), and TL84 (store/office light) as reference illuminants. A modified metamerism index (Mod-M) and hue-angle ratios were calculated to express differences between tooth and tab colour relative to the difference observed under D65 illumination. The Mod-M for teeth and tabs was greater than unity (indicating a greater colour difference relative to D65) by 57.1% for A and by 49.3% for TL84. Hue-angle ratios of teeth and tabs using the test illuminants were different from those obtained using the standard illuminant D65. If teeth and shade tab matching is conducted using daylight illumination, the colour difference may not be the same under other lighting conditions, leading to perceptible, or even unacceptable, colour differences under these conditions.

  3. Comment on 'New Brans-Dicke wormholes'

    SciTech Connect

    Bhadra, Arunava; Simaciu, Ion; Nandi, Kamal Kanti; Zhang Yuanzhong

    2005-06-15

    It is shown that the recently claimed two new Brans-Dicke wormhole solutions [F. He and S-W. Kim, Phys. Rev. D 65, 084022 (2002)] are not really new solutions. They are just the well known Brans-Dicke solutions of Class I and II in a different conformal gauge.

  4. 40 CFR Appendix 1 to Part 3 - Priority Reports

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    .... 1 Appendix 1 to Part 3—Priority Reports Category Description 40 CFR Citation Required Reports State... in 40 CFR 65.6(c) 65.5(d), 65.5(e). Continuous Emissions Monitoring Quarterly emissions monitoring... hazardous waste that was placed in hazardous waste management units in noncompliance with 40 CFR...

  5. 40 CFR Appendix 1 to Part 3 - Priority Reports

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    .... 1 Appendix 1 to Part 3—Priority Reports Category Description 40 CFR Citation Required Reports State... in 40 CFR 65.6(c) 65.5(d), 65.5(e). Continuous Emissions Monitoring Quarterly emissions monitoring... hazardous waste that was placed in hazardous waste management units in noncompliance with 40 CFR...

  6. Spectral data compression using weighted principal component analysis with consideration of human visual system and light sources

    NASA Astrophysics Data System (ADS)

    Cao, Qian; Wan, Xiaoxia; Li, Junfeng; Liu, Qiang; Liang, Jingxing; Li, Chan

    2016-08-01

    This paper proposed two weight functions based on principal component analysis (PCA) to reserve more colorimetric information in spectral data compression process. One weight function consisted of the CIE XYZ color-matching functions representing the characteristic of the human visual system, while another was made up of the CIE XYZ color-matching functions of human visual system and relative spectral power distribution of the CIE standard illuminant D65. The improvement obtained from the proposed two methods were tested to compress and reconstruct the reflectance spectra of 1600 glossy Munsell color chips and 1950 Natural Color System color chips as well as six multispectral images. The performance was evaluated by the mean values of color difference under the CIE 1931 standard colorimetric observer and the CIE standard illuminant D65 and A. The mean values of root mean square errors between the original and reconstructed spectra were also calculated. The experimental results show that the proposed two methods significantly outperform the standard PCA and another two weighted PCA in the aspects of colorimetric reconstruction accuracy with very slight degradation in spectral reconstruction accuracy. In addition, weight functions with the CIE standard illuminant D65 can improve the colorimetric reconstruction accuracy compared to weight functions without the CIE standard illuminant D65.

  7. 40 CFR Appendix 1 to Part 3 - Priority Reports

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    .... 1 Appendix 1 to Part 3—Priority Reports Category Description 40 CFR Citation Required Reports State... in 40 CFR 65.6(c) 65.5(d), 65.5(e). Continuous Emissions Monitoring Quarterly emissions monitoring... hazardous waste that was placed in hazardous waste management units in noncompliance with 40 CFR...

  8. 40 CFR Appendix 1 to Part 3 - Priority Reports

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    .... 1 Appendix 1 to Part 3—Priority Reports Category Description 40 CFR Citation Required Reports State... in 40 CFR 65.6(c) 65.5(d), 65.5(e). Continuous Emissions Monitoring Quarterly emissions monitoring... hazardous waste that was placed in hazardous waste management units in noncompliance with 40 CFR...

  9. 40 CFR Appendix 1 to Part 3 - Priority Reports

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    .... 1 Appendix 1 to Part 3—Priority Reports Category Description 40 CFR Citation Required Reports State... in 40 CFR 65.6(c) 65.5(d), 65.5(e). Continuous Emissions Monitoring Quarterly emissions monitoring... hazardous waste that was placed in hazardous waste management units in noncompliance with 40 CFR...

  10. 77 FR 29692 - Segun M. Rasaki, M.D.; Decision and Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-18

    ...., 67 FR 35,582 (DEA 2002); Michael G. Dolin, M.D., 65 Fed. Reg. 5661 (DEA 2000); see also Philip E...'s action at which he may ultimately prevail.'' Kamal Tiwari, M.D., 76 FR 71604, 71606 (2011); see also Bourne Pharmacy, Inc., 72 FR 18273, 18274 (2007); Anne Lazar Thorn, 62 FR 12847...

  11. Collaborative annotation of 3D crystallographic models.

    PubMed

    Hunter, J; Henderson, M; Khan, I

    2007-01-01

    This paper describes the AnnoCryst system-a tool that was designed to enable authenticated collaborators to share online discussions about 3D crystallographic structures through the asynchronous attachment, storage, and retrieval of annotations. Annotations are personal comments, interpretations, questions, assessments, or references that can be attached to files, data, digital objects, or Web pages. The AnnoCryst system enables annotations to be attached to 3D crystallographic models retrieved from either private local repositories (e.g., Fedora) or public online databases (e.g., Protein Data Bank or Inorganic Crystal Structure Database) via a Web browser. The system uses the Jmol plugin for viewing and manipulating the 3D crystal structures but extends Jmol by providing an additional interface through which annotations can be created, attached, stored, searched, browsed, and retrieved. The annotations are stored on a standardized Web annotation server (Annotea), which has been extended to support 3D macromolecular structures. Finally, the system is embedded within a security framework that is capable of authenticating users and restricting access only to trusted colleagues.

  12. Models for ionic contribution to the complex dielectric constant of nematic liquid crystals.

    PubMed

    Alexe-Ionescu, A L; Barbero, G; Lelidis, I

    2009-12-01

    We analyze the models that account the ionic contribution to the complex dielectric constant of a nematic liquid crystal. We compare the predictions of the model of [Sawada, Mol. Cryst. Liq. Cryst. Sci. Technol., Sect. A 318, 225 (1998)] based on the assumption that the electric field in the liquid coincides with the applied one, with the model of Macdonald where the electric field in the sample is determined in self-consistent manner by solving the equation of Poisson. We show that the model of Sawada , widely used to determine the bulk density of ions and their diffusion coefficient in liquid crystal cells, predicts a thickness dependence of the real and imaginary parts of the dielectric constant different from that predicted by the model of Macdonald. On the contrary, the predictions of the two models coincide for what concerns the frequency dependencies of the two components of the dielectric constant. By considering a typical case, we show that the numerical values of the ionic properties derived by means of the model of Sawada may differ even more than 1 order of magnitude by those predicted by the model of Macdonald. A rescaling procedure allowing to evaluate the bulk density of ions and the ionic diffusion coefficient determined by means of the model of Sawada in agreement with the one of Macdonald is proposed.

  13. FOREWORD: Heterogenous nucleation and microstructure formation—a scale- and system-bridging approach Heterogenous nucleation and microstructure formation—a scale- and system-bridging approach

    NASA Astrophysics Data System (ADS)

    Emmerich, H.

    2009-11-01

    : Springer) [2] Mutaftschiev B 1993 Handbook on Crystal Growth ed D T J Hurle (Amsterdam: North-Holland) p 187 [3] Lacmann R and Schmidt P 1977 Current Topics in Materials Science ed E Kaldis and H J Scheel (Amsterdam: North-Holland) vol 2, pp 301-25 [4] Skripov V P 1977 Current Topics in Materials Scierce ed by E Kaldis and H J Scheel (Amsterdam: North-Holland) 327-78 [5] Chayen N E 1997 J. Appl. Crystallogr. 30 198 [6] Cho J and Thompson C V 1989 Appl. Phys. Lett. 54 2577 [7] Boettinger W J, Coriell S R, Greer A L, Karma A, Kurz W, Rappaz M, and Trivedi R 2000 Acta mater. 48 43 [8] www.spp1296.rwth-aachen.de [9] Volmer M and Weber A 1926 Z. Phys. Chemie. 119 227 [10] Becker R and Döring W 1935 Ann. Phys. 24 719 [11] Turnbull D and Fisher J C 1949 J. Chem. Phys. 17 71 [12] Oxtoby D W 1992 J. Phys.: Condens. Matter 4 7627 [13] Gránásy L and Iglói F 1997 J. Chem. Phys. 107 3634 [14] Gránásy L, Börzsönyi T, Pusztai T 2003 Interface and Transport Dynamics ed H Emmerich, B Nestler and M Schreckenberg (Berlin: Springer) p 190 [15] Emmerich H and Siquieri R 2005 Numerical Heat Transfer ed A Nowack and R A Bialecki [16] Gránásy L 1993 J. Non-Cryst. Solids 162 301 Dragnevski K I, Cochrane R F and Mullis A 2004 Mat. Sci. Eng. A 375-377 479 [17] Sood A K 1991 Solid State Physics 45 1

  14. A short history of medical informatics in bosnia and herzegovina.

    PubMed

    Masic, Izet

    2014-02-01

    The health informatics profession in Bosnia and Herzegovina has relatively long history. Thirty five years from the introduction of the first automatic manipulation of data, thirty years from the establishment of Society for Medical Informatics BiH, twenty years from the establishment of the Scientific journal "Acta Informatica Medica (Acta Inform Med", indexed in PubMed, PubMed Central Scopus, Embase, etc.), twenty years on from the establishment of the first Cathedra for Medical Informatics on Biomedical Faculties in Bosnia and Herzegovina, ten years on from the introduction of the method of "Distance learning" in medical curriculum. The author of this article is eager to mark the importance of the above mentioned Anniversaries in the development of Health informatics in Bosnia and Herzegovina and have attempted, very briefly, to present the most significant events and persons with essential roles throughout this period.

  15. A Short History of Medical Informatics in Bosnia and Herzegovina

    PubMed Central

    Masic, Izet

    2014-01-01

    The health informatics profession in Bosnia and Herzegovina has relatively long history. Thirty five years from the introduction of the first automatic manipulation of data, thirty years from the establishment of Society for Medical Informatics BiH, twenty years from the establishment of the Scientific journal “Acta Informatica Medica (Acta Inform Med”, indexed in PubMed, PubMed Central Scopus, Embase, etc.), twenty years on from the establishment of the first Cathedra for Medical Informatics on Biomedical Faculties in Bosnia and Herzegovina, ten years on from the introduction of the method of “Distance learning” in medical curriculum. The author of this article is eager to mark the importance of the above mentioned Anniversaries in the development of Health informatics in Bosnia and Herzegovina and have attempted, very briefly, to present the most significant events and persons with essential roles throughout this period. PMID:24648621

  16. Iron potentiates nitric oxide scavenging by dithiocarbamates in tissue of septic shock mice.

    PubMed

    Komarov, A M; Mak, I T; Weglicki, W B

    1997-10-24

    Vanin and co-workers (Kubrina et al., Biochim. Biophys. Acta 1176 (1993) 240-244; Mikoyan et al., Biochim. Biophys. Acta 1269 (1995) 19-24) reported that short term (30 min) iron (Fe) exposure potentiates nitric oxide (NO) production in tissues of septic shock mice, based on increased formation of NO complex by diethyldithiocarbamate (DETC). We have reexamined the effect of Fe administration in mice treated with Escherichia coli lipopolysaccharide (LPS) and have not found any changes in nitrosylhemoglobin (HbNO) or (NOs- + NO3-) levels in blood 30 min after Fe-citrate complex injection. However, Fe-citrate promotes NO complex formation by iron-dependent NO traps: DETC, pyrrolidinedithiocarbamate (PDTC) and N-methyl-D-glucamine dithiocarbamate (MGD), when given simultaneously at 6 h after LPS. Rather than potentiation of NO production, our data support that short-term iron treatment (30 min) enhances in vivo spin trapping ability of dithiocarbamate. PMID:9375797

  17. National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions

    ClinicalTrials.gov

    2015-12-08

    Marfan Syndrome; Turner Syndrome; Ehlers-Danlos Syndrome; Loeys-Dietz Syndrome; FBN1, TGFBR1, TGFBR2, ACTA2 or MYH11 Genetic Mutation; Bicuspid Aortic Valve Without Known Family History; Bicuspid Aortic Valve With Family History; Bicuspid Aortic Valve With Coarctation; Familial Thoracic Aortic Aneurysm and Dissections; Shprintzen-Goldberg Syndrome; Other Aneur/Diss of Thoracic Aorta Not Due to Trauma, <50yo; Other Congenital Heart Disease

  18. MicroRNA-208b Alleviates Post-Infarction Myocardial Fibrosis in a Rat Model by Inhibiting GATA4

    PubMed Central

    Zhou, Chaoyuan; Cui, Qintao; Su, Guobao; Guo, Xiaoliang; Liu, Xiaochen; Zhang, Jie

    2016-01-01

    Background Myocardial infarction affects the health of many people. Post-infarction myocardial fibrosis has attracted much attention, but details of the mechanism remain elusive. In this study, the role of microRNA-208b (miR-208b) in modulating post-infarction myocardial fibrosis and the related mechanism were investigated. Material/Methods A rat model of myocardial infarction induced by ligating the left anterior descending artery was used to analyze the expression and roles of miR-208b by overexpression with the lentivirus vector of pre-miR-208b. Myocardial function was assessed and the expression of fibrosis-related factors type I collagen (COL1) and ACTA2 (alias αSMA) was detected. Myocardial fibroblasts isolated from newborn rats were transfected with luciferase reporter vectors containing wild-type or mutant Gata4 3′ UTR to verify the relationship between Gata4 and miR-208b. We then transfected the specific small interference RNA of Gata4 to detect changes in COL1 and ACTA2. Results miR-208b was down-regulated in hearts of model rats (P<0.01). Overexpressing miR-208b improved myocardial functions, such as reducing the infarction area (P<0.05) and promoting LVEF and LVFS (P<0.01), and inhibited COL1 and ACTA2 (P<0.01). Luciferase reporter assay proved Gata4 to be the direct target of miR-208b, with the target sequence in the 3′UTR. Inhibiting GATA4 resulted in the down-regulation of COL1 and ACTA2, suggesting that the role of miR-208b was achieved via regulating GATA4. Conclusions This study demonstrates the protective function of miR-208b via GATA4 in post-infarction myocardial fibrosis, providing a potential therapeutic target for treating myocardial fibrosis. PMID:27236543

  19. What Will They Learn? A Survey of Core Requirements at Our Nation's Colleges and Universities. 2011-12

    ERIC Educational Resources Information Center

    Kempson, Lauri; Bako, Tom; Markley, Eric

    2012-01-01

    What does it mean to be a college graduate? One knows about the time and ever-increasing amount of money that a diploma demands. But when it comes down to what matters--the skills and knowledge acquired--what does a college degree mean? That is the question the American Council of Trustees and Alumni (ACTA) answers in this book. Inside one will…

  20. Chinese duo fired for scientific fraud

    NASA Astrophysics Data System (ADS)

    Jiao, Li

    2010-02-01

    A major case of academic fraud in China has led to calls for the country to adopt a new system of academic evaluation that steers away from heavily supporting scientists who publish the most papers. The calls have been made after some 70 papers published by Chinese scientists in Acta Crystallographica Section E were retracted from the journal late last year. The authors acknowledged that their analysis had been fabricated.

  1. The glycoprotein-hormones activin A and inhibin A interfere with dendritic cell maturation

    PubMed Central

    Segerer, Sabine E; Müller, Nora; Brandt, Jens van den; Kapp, Michaela; Dietl, Johannes; Reichardt, Holger M; Rieger, Lorenz; Kämmerer, Ulrike

    2008-01-01

    Background Pregnancy represents an exclusive situation in which the immune and the endocrine system cooperate to prevent rejection of the embryo by the maternal immune system. While immature dendritic cells (iDC) in the early pregnancy decidua presumably contribute to the establishment of peripheral tolerance, glycoprotein-hormones of the transforming growth factor beta (TGF-beta) family including activin A (ActA) and inhibin A (InA) are candidates that could direct the differentiation of DCs into a tolerance-inducing phenotype. Methods To test this hypothesis we generated iDCs from peripheral-blood-monocytes and exposed them to TGF-beta1, ActA, as well as InA and Dexamethasone (Dex) as controls. Results Both glycoprotein-hormones prevented up-regulation of HLA-DR during cytokine-induced DC maturation similar to Dex but did not influence the expression of CD 40, CD 83 and CD 86. Visualization of the F-actin cytoskeleton confirmed that the DCs retained a partially immature phenotype under these conditions. The T-cell stimulatory capacity of DCs was reduced after ActA and InA exposure while the secretion of cytokines and chemokines was unaffected. Conclusion These findings suggest that ActA and InA interfere with selected aspects of DC maturation and may thereby help preventing activation of allogenic T-cells by the embryo. Thus, we have identified two novel members of the TGF-beta superfamily that could promote the generation of tolerance-inducing DCs. PMID:18460206

  2. [Communication and dental practice. Practica in social dentistry and information].

    PubMed

    Gorter, R C; den Dekker, J; Schut, H; Eijkman, M A

    1994-09-01

    An overview is presented of several undergraduate courses given by the Department of Social Dentistry and Dental Health Education (ACTA). A short description of the contents of courses in communication skills, treatment of anxious patients and practice management is given together with the results of a student-evaluation. Students consider these courses useful and relevant for future dental practice. This is especially true in case the direct relevance for clinical practice is clear.

  3. Cosmochemistry and Mineralogy of Primitive Meteorites

    NASA Technical Reports Server (NTRS)

    Buseck, Peter R.

    2003-01-01

    We have produced significant research results during the grant period. These have been reported in five papers published in Geochimica et Cosmochimica Acta and Meteoritics and Planetary Science and several others are in review. We also presented 17 abstracted talks at professional meetings. The citations are given in section 2, and abstracts of the papers are provided in section 3. The full papers are available on request.

  4. Retraction: Two novel duck antibacterial peptides, avian β-defensins 9 and 10, with antimicrobial activity.

    PubMed

    2013-01-01

    The article by Ma et al. that published in the Journal of Microbiology and Biotechnology (2009, 19: 1447-1455) was used the same data in two journal articles (Acta Veterinaria et Zootechnica Sinica, 2009, 40(9): 1320-1326, Scientia Agricultura Sinica, 2009, 42(4): 1406-1412). Therefore, the article is retracted from JMB as a misconduct of the authors. JMB as the publisher regrets for any inconvenience may have caused by the retraction to readers.

  5. [140 years of CMA--53 years of AMSC].

    PubMed

    Lipozenčić, Jasna

    2014-01-01

    Croatian Academy of Medical Sciences was established in 1961 as the Commission for Scientific Research of the Croatian Medical Association Main Committee. In 1983 was separated from the Croatian Medical Association and became an independent organization--Croatian Academy of Medical Sciences. The Academy is a society of chosen scientists dealing with promotion of medical sciences to improve public health. To introduce Croatian medicine to the world the Academy publishes journals Acta Medica Croatica, Socijalna psihijatrija and Croatian Medical Journal.

  6. Thin film adhesion by nanoindentation-induced superlayers. Final report

    SciTech Connect

    Gerberich, William W.; Volinsky, A.A.

    2001-06-01

    This work has analyzed the key variables of indentation tip radius, contact radius, delamination radius, residual stress and superlayer/film/interlayer properties on nanoindentation measurements of adhesion. The goal to connect practical works of adhesion for very thin films to true works of adhesion has been achieved. A review of this work titled ''Interfacial toughness measurements of thin metal films,'' which has been submitted to Acta Materialia, is included.

  7. Determination of Structural and Vibrational Properties of 5-QUINOLINECARBOXALDEHYDE Using Experimental Ft-Ir Ft-Raman Techniques and Theoretical HF and DFT Methods

    NASA Astrophysics Data System (ADS)

    Kumru, Mustafa; Kocademir, Mustafa; Bardakci, Tayyibe

    2013-06-01

    Quinoline derivatives have been used in several pharmaceuticals. They have vital roles in regulating the functions of DNA and cancerous cells. It's necessary to determine the structures and spectroscopic properties of quinoline derivates. In this study, the FT-IR (including mid and far regions) and FT-Raman spectra of 5-quinolinecarboxaldehyde have been investigated. Hartree-Fock (HF) and density functional B3LYP calculations have also been employed with the 6-311++G(d,p) basis set for investigating the structural and spectroscopic properties of the cis and trans conformers of 5-quinolinecarboxaldehyde. Experimental and theoretical results have been compared and the results are in good agreement with each other. Keywords: 5-quinolinecarboxaldehyde; Vibrational Spectroscopy; FT-IR spectra; FT-Raman spectra; Vibrational Modes; HF; DFT [1] V. Kucuk, A. Altun, M. Kumru, Spectrochim. Acta Part A 85(2012)92-98 [2] M. Kumru, V. Kucuk, T. Bardakci, Spectrochim. Acta Part A 90(2012)28-34 [3] M. Kumru, V. Kucuk, M. Kocademir, Spectrochim. Acta Part A, 96 (2012) 242-251 We thank the Turkish Scientific and Technical Research Council (TUBITAK) for their financial support through National Postdoctoral Research Scholarship Programme and Scientific Research Fund of Fatih University under the project number P50011001 G (1457).

  8. Genetic homogeneity among Listeria monocytogenes strains from infected patients and meat products from two geographic locations determined by phenotyping, ribotyping and PCR analysis of virulence genes.

    PubMed

    Jaradat, Z W; Schutze, G E; Bhunia, A K

    2002-06-01

    Thirty Listeria monocytogenes isolates from human patients and foods originated from two different geographic locations without any epidemiological relations were analyzed for their genotypic and phenotypic virulence gene expressions and genetic relatedness. All strains contained virulence genes, inlA, inlB, actA, hlyA, plcA and plcB, with expected product size in PCR assay except for the actA gene. Some strains produced actA gene product of 268 and others 385 bp. Phenotypically, all were hemolytic but showed variable expressions of phospholipase activity. Ribotyping classified isolates into 12 different groups based on the similarity to DuPont Identification numbers (DID), which consisted primarily of clinical or food isolates or both. Cluster analysis also indicated possible existence of clones of L. monocytogenes that are found in food or human hosts or are evenly distributed between these two. Two isolates (F1 from food and CHL1250 from patient) had unique ribotype patterns that were not previously reported in the RiboPrinter database. This study indicates distribution of diverse L. monocytogenes strains in clinical and food environments. The isolates showed 92-99% genetic homogeneity, in spite of their origins from two different geographic locations and environments.

  9. Retraction statement: Dynamics of Cytochrome C Oxidase Activity in Acute Ischemic Stroke' by Selaković, V.M., Jovanović, M.D., Mihajlović, R.R. and Radenović, L.L.J.

    PubMed

    2016-10-01

    The above article from Acta Neurologica Scandinavica, published online on 7 April 2005 in Wiley Online Library (wileyonlinelibrary.com) and in Volume 111, pp. 329-332, has been retracted by agreement between the journal Editor in Chief, Professor Elinor Ben-Menachem, and John Wiley & Sons Ltd. The article has been retracted because a similar article had previously been published in the Jugoslovenska medicinska biohemija in 2003. The authors presumed that since the journal was no longer existing, they felt the need to re-publish their work in Acta Neuorologica Scandinavica. However, in the consideration of the Journal, this constitutes dual publication. References SelakovićVM, JovanovićMD, MihajlovićR, RadenovićLLJ. Cytochrome c oxidase in patients with acute ischaemic brain disease. Jugoslovenska medicinska biohemija. 2003;22:329-334. SelakovićVM, JovanovićMD, MihajlovićRR, RadenovićLLJ. Dynamics of cytochrome c oxidase activity in acute ischemic stroke. Acta Neurol Scand. 2005;111:329-332.

  10. A focal adhesion factor directly linking intracellularly motile Listeria monocytogenes and Listeria ivanovii to the actin-based cytoskeleton of mammalian cells.

    PubMed

    Chakraborty, T; Ebel, F; Domann, E; Niebuhr, K; Gerstel, B; Pistor, S; Temm-Grove, C J; Jockusch, B M; Reinhard, M; Walter, U

    1995-04-01

    The surface-bound ActA polypeptide of the intracellular bacterial pathogen Listeria monocytogenes is the sole listerial factor needed for recruitment of host actin filaments by intracellularly motile bacteria. Here we report that following Listeria infection the host vasodilator-stimulated phosphoprotein (VASP), a microfilament- and focal adhesion-associated substrate of both the cAMP- and cGMP-dependent protein kinases, accumulates on the surface of intracytoplasmic bacteria prior to the detection of F-actin 'clouds'. VASP remains associated with the surface of highly motile bacteria, where it is polarly located, juxtaposed between one extremity of the bacterial surface and the front of the actin comet tail. Since actin filament polymerization occurs only at the very front of the tail, VASP exhibits properties of a host protein required to promote actin polymerization. Purified VASP binds directly to the ActA polypeptide in vitro. A ligand-overlay blot using purified radiolabelled VASP enabled us to identify the ActA homologue of the related intracellular motile pathogen, Listeria ivanovii, as a protein with a molecular mass of approximately 150 kDa. VASP also associates with actin filaments recruited by another intracellularly motile bacterial pathogen, Shigella flexneri. Hence, by the simple expedient of expressing surface-bound attractor molecules, bacterial pathogens effectively harness cytoskeletal components to achieve intracellular movement.

  11. Skeletal and cardiac α-actin isoforms differently modulate myosin cross-bridge formation and myofibre force production.

    PubMed

    Ochala, Julien; Iwamoto, Hiroyuki; Ravenscroft, Gianina; Laing, Nigel G; Nowak, Kristen J

    2013-11-01

    Multiple congenital myopathies, including nemaline myopathy, can arise due to mutations in the ACTA1 gene encoding skeletal muscle α-actin. The main characteristics of ACTA1 null mutations (absence of skeletal muscle α-actin) are generalized skeletal muscle weakness and premature death. A mouse model (ACTC(Co)/KO) mimicking these conditions has successfully been rescued by transgenic over-expression of cardiac α-actin in skeletal muscles using the ACTC gene. Nevertheless, myofibres from ACTC(Co)/KO animals generate less force than normal myofibres (-20 to 25%). To understand the underlying mechanisms, here we have undertaken a detailed functional study of myofibres from ACTC(Co)/KO rodents. Mechanical and X-ray diffraction pattern analyses of single membrane-permeabilized myofibres showed, upon maximal Ca(2+) activation and under rigor conditions, lower stiffness and disrupted actin-layer line reflections in ACTC(Co)/KO when compared with age-matched wild-types. These results demonstrate that in ACTC(Co)/KO myofibres, the presence of cardiac α-actin instead of skeletal muscle α-actin alters actin conformational changes upon activation. This later finely modulates the strain of individual actomyosin interactions and overall lowers myofibre force production. Taken together, the present findings provide novel primordial information about actin isoforms, their functional differences and have to be considered when designing gene therapies for ACTA1-based congenital myopathies. PMID:23784376

  12. Hypertrophy and dietary tyrosine ameliorate the phenotypes of a mouse model of severe nemaline myopathy.

    PubMed

    Nguyen, Mai-Anh T; Joya, Josephine E; Kee, Anthony J; Domazetovska, Ana; Yang, Nan; Hook, Jeff W; Lemckert, Frances A; Kettle, Emma; Valova, Valentina A; Robinson, Philip J; North, Kathryn N; Gunning, Peter W; Mitchell, Christina A; Hardeman, Edna C

    2011-12-01

    Nemaline myopathy, the most common congenital myopathy, is caused by mutations in genes encoding thin filament and thin filament-associated proteins in skeletal muscles. Severely affected patients fail to survive beyond the first year of life due to severe muscle weakness. There are no specific therapies to combat this muscle weakness. We have generated the first knock-in mouse model for severe nemaline myopathy by replacing a normal allele of the α-skeletal actin gene with a mutated form (H40Y), which causes severe nemaline myopathy in humans. The Acta1(H40Y) mouse has severe muscle weakness manifested as shortened lifespan, significant forearm and isolated muscle weakness and decreased mobility. Muscle pathologies present in the human patients (e.g. nemaline rods, fibre atrophy and increase in slow fibres) were detected in the Acta1(H40Y) mouse, indicating that it is an excellent model for severe nemaline myopathy. Mating of the Acta1(H40Y) mouse with hypertrophic four and a half LIM domains protein 1 and insulin-like growth factor-1 transgenic mice models increased forearm strength and mobility, and decreased nemaline pathologies. Dietary L-tyrosine supplements also alleviated the mobility deficit and decreased the chronic repair and nemaline rod pathologies. These results suggest that L-tyrosine may be an effective treatment for muscle weakness and immobility in nemaline myopathy. PMID:22067542

  13. Retraction statement: Dynamics of Cytochrome C Oxidase Activity in Acute Ischemic Stroke' by Selaković, V.M., Jovanović, M.D., Mihajlović, R.R. and Radenović, L.L.J.

    PubMed

    2016-10-01

    The above article from Acta Neurologica Scandinavica, published online on 7 April 2005 in Wiley Online Library (wileyonlinelibrary.com) and in Volume 111, pp. 329-332, has been retracted by agreement between the journal Editor in Chief, Professor Elinor Ben-Menachem, and John Wiley & Sons Ltd. The article has been retracted because a similar article had previously been published in the Jugoslovenska medicinska biohemija in 2003. The authors presumed that since the journal was no longer existing, they felt the need to re-publish their work in Acta Neuorologica Scandinavica. However, in the consideration of the Journal, this constitutes dual publication. References SelakovićVM, JovanovićMD, MihajlovićR, RadenovićLLJ. Cytochrome c oxidase in patients with acute ischaemic brain disease. Jugoslovenska medicinska biohemija. 2003;22:329-334. SelakovićVM, JovanovićMD, MihajlovićRR, RadenovićLLJ. Dynamics of cytochrome c oxidase activity in acute ischemic stroke. Acta Neurol Scand. 2005;111:329-332. PMID:27592845

  14. Crystallization, data collection and phasing of black-eyed pea trypsin/chymotrypsin inhibitor in complex with bovine beta-trypsin.

    PubMed

    Barbosa, J A R G; Teles, R C L; Forrer, V P; Guimarães, B G; Medrano, F J; Ventura, M M; Freitas, S M

    2003-10-01

    The black-eyed pea trypsin and chymotrypsin inhibitor (BTCI) is a Bowman-Birk-type inhibitor from Vigna unguiculata seeds. A complex of BTCI with bovine beta-trypsin was crystallized by the hanging-drop vapour-diffusion method with ammonium sulfate as precipitant. Crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 59.3, b = 61.8, c = 80.0 A. Diffraction data were collected to 2.36 A resolution and were processed to give an overall R(sym) of 0.137. The Matthews coefficient for one complex per asymmetric unit is 2.2 A(3) Da(-1), with a corresponding solvent content of 43%. After molecular replacement and initial refinement, the model gives an R(cryst) of 0.361 and an R(free) of 0.432.

  15. A new crystal form of human histidine triad nucleotide-binding protein 1 (hHINT1) in complex with adenosine 5′-monophosphate at 1.38 Å resolution

    PubMed Central

    Dolot, Rafał; Ozga, Magdalena; Włodarczyk, Artur; Krakowiak, Agnieszka; Nawrot, Barbara

    2012-01-01

    Histidine triad nucleotide-binding protein 1 (HINT1) represents the most ancient and widespread branch of the histidine triad protein superfamily. HINT1 plays an important role in various biological processes and has been found in many species. Here, the structure of the human HINT1–adenosine 5′-monophosphate (AMP) complex at 1.38 Å resolution obtained from a new monoclinic crystal form is reported. The final structure has R cryst = 0.1207 (R free = 0.1615) and the model exhibits good stereochemical quality. Detailed analysis of the high-resolution data allowed the details of the protein structure to be updated in comparison to the previously published data. PMID:22869114

  16. Examination of methods to determine free-ion diffusivity and number density from analysis of electrode polarization.

    PubMed

    Wang, Yangyang; Sun, Che-Nan; Fan, Fei; Sangoro, Joshua R; Berman, Marc B; Greenbaum, Steve G; Zawodzinski, Thomas A; Sokolov, Alexei P

    2013-04-01

    Electrode polarization analysis is frequently used to determine free-ion diffusivity and number density in ionic conductors. In the present study, this approach is critically examined in a wide variety of electrolytes, including aqueous and nonaqueous solutions, polymer electrolytes, and ionic liquids. It is shown that the electrode polarization analysis based on the Macdonald-Trukhan model [J. Chem. Phys. 124, 144903 (2006); J. Non-Cryst. Solids 357, 3064 (2011)] progressively fails to give reasonable values of free-ion diffusivity and number density with increasing salt concentration. This should be expected because the original model of electrode polarization is designed for dilute electrolytes. An empirical correction method which yields ion diffusivities in reasonable agreement with pulsed-field gradient nuclear magnetic resonance measurements is proposed. However, the analysis of free-ion diffusivity and number density from electrode polarization should still be exercised with great caution because there is no solid theoretical justification for the proposed corrections. PMID:23679415

  17. Examination of methods to determine free-ion diffusivity and number density from analysis of electrode polarization

    SciTech Connect

    Wang, Yangyang; Sun, Che-Nan; Fan, Fei; Sangoro, Joshua R; Berman, Marc; Greenbaum, Steve; Zawodzinski, Thomas; Sokolov, Alexei P

    2013-01-01

    Electrode polarization analysis is frequently used to determine free-ion diffusivity and number density in ionic conductors. In the present study, this approach is critically examined in a wide variety of electrolytes, including aqueous and nonaqueous solutions, polymer electrolytes, and ionic liquids. It is shown that the electrode polarization analysis based on theMacdonald-Trukhan model [J. Chem. Phys. 124, 144903 (2006); J. Non-Cryst. Solids 357, 3064 (2011)] progressively fails to give reasonable values of free-ion diffusivity and number density with increasing salt concentration. This should be expected because the original model of electrode polarization is designed for dilute electrolytes. An empirical correction method which yields ion diffusivities in reasonable agreement with pulsed-field gradient nuclear magnetic resonance measurements is proposed. However, the analysis of free-ion diffusivity and number density from electrode polarization should still be exercised with great caution because there is no solid theoretical justification for the proposed corrections.

  18. Electrical, Thermal, and Magnetic Properties of Single Crystal CaMn2O4 Marokite

    NASA Astrophysics Data System (ADS)

    White, B. D.; Neumeier, J. J.; Souza, J. A.; Chiorescu, C.; Cohn, J. L.

    2008-03-01

    CaMn2O4 was first described [1] in 1963 as a natural mineral called Marokite. Since its discovery, it has been studied as a minor structural impurity phase in CMR- related CaMnO3 and for its structural similarities to high-pressure phases of spinel-oxide compounds. However, little attention has previously been paid to physical properties beyond its temperature-dependent magnetization. We will present a detailed physical properties study of CaMn2O4 single crystals grown by the optical floating zone method. [2] These measurements, several of which display anisotropy as a result of an orthorhombic crystal structure, include electrical transport, thermal transport, thermal expansion, heat capacity, and magnetization. [1] C. Gaudefroy, G. Jouravsky, F. Permingeat, Bull. Soc. Franc. Min'er. Crist. 86 (1963) 359. [2] B. D. White, C. A. M. dos Santos, J. A. Souza, K. J. McClellan, J. J. Neumeier submitted to J. Cryst. Growth.

  19. Crystal structure of ribosomal protein L1 from the bacterium Aquifex aeolicus

    NASA Astrophysics Data System (ADS)

    Nikonova, E. Yu.; Tishchenko, S. V.; Gabdulkhakov, A. G.; Shklyaeva, A. A.; Garber, M. B.; Nikonov, S. V.; Nevskaya, N. A.

    2011-07-01

    The crystal structure of ribosomal protein L1 from the bacterium Aquifex aeolicus was solved by the molecular-replacement method and refined to R cryst = 19.4% and R free = 25.1% at 2.1 Å protein consists of two domains linked together by a flexible hinge region. In the structure under consideration, the domains are in close proximity and adopt a closed conformation. Earlier, this conformation has been found in the structure of protein L1 from the bacterium Thermus thermophilus, whereas the structures of archaeal L1 proteins and the structures of all L1 proteins in the RNA-bound form have an open conformation. The fact that a closed conformation was found in the structures of two L1 proteins which crystallize in different space groups and belong to different bacteria suggests that this conformation is a characteristic feature of L1 bacterial proteins in the free form.

  20. Crystallographic data processing for free-electron laser sources

    PubMed Central

    White, Thomas A.; Barty, Anton; Stellato, Francesco; Holton, James M.; Kirian, Richard A.; Zatsepin, Nadia A.; Chapman, Henry N.

    2013-01-01

    A processing pipeline for diffraction data acquired using the ‘serial crystallography’ methodology with a free-electron laser source is described with reference to the crystallographic analysis suite CrystFEL and the pre-processing program Cheetah. A detailed analysis of the nature and impact of indexing ambiguities is presented. Simulations of the Monte Carlo integration scheme, which accounts for the partially recorded nature of the diffraction intensities, are presented and show that the integration of partial reflections could be made to converge more quickly if the bandwidth of the X-rays were to be increased by a small amount or if a slight convergence angle were introduced into the incident beam. PMID:23793149

  1. Crystallographic data processing for free-electron laser sources.

    PubMed

    White, Thomas A; Barty, Anton; Stellato, Francesco; Holton, James M; Kirian, Richard A; Zatsepin, Nadia A; Chapman, Henry N

    2013-07-01

    A processing pipeline for diffraction data acquired using the `serial crystallography' methodology with a free-electron laser source is described with reference to the crystallographic analysis suite CrystFEL and the pre-processing program Cheetah. A detailed analysis of the nature and impact of indexing ambiguities is presented. Simulations of the Monte Carlo integration scheme, which accounts for the partially recorded nature of the diffraction intensities, are presented and show that the integration of partial reflections could be made to converge more quickly if the bandwidth of the X-rays were to be increased by a small amount or if a slight convergence angle were introduced into the incident beam.

  2. HOMSTRAD: a database of protein structure alignments for homologous families.

    PubMed

    Mizuguchi, K; Deane, C M; Blundell, T L; Overington, J P

    1998-11-01

    We describe a database of protein structure alignments for homologous families. The database HOMSTRAD presently contains 130 protein families and 590 aligned structures, which have been selected on the basis of quality of the X-ray analysis and accuracy of the structure. For each family, the database provides a structure-based alignment derived using COMPARER and annotated with JOY in a special format that represents the local structural environment of each amino acid residue. HOMSTRAD also provides a set of superposed atomic coordinates obtained using MNYFIT, which can be viewed with a graphical user interface or used for comparative modeling studies. The database is freely available on the World Wide Web at: http://www-cryst.bioc.cam. ac.uk/-homstrad/, with search facilities and links to other databases.

  3. Crystallographic data processing for free-electron laser sources.

    PubMed

    White, Thomas A; Barty, Anton; Stellato, Francesco; Holton, James M; Kirian, Richard A; Zatsepin, Nadia A; Chapman, Henry N

    2013-07-01

    A processing pipeline for diffraction data acquired using the `serial crystallography' methodology with a free-electron laser source is described with reference to the crystallographic analysis suite CrystFEL and the pre-processing program Cheetah. A detailed analysis of the nature and impact of indexing ambiguities is presented. Simulations of the Monte Carlo integration scheme, which accounts for the partially recorded nature of the diffraction intensities, are presented and show that the integration of partial reflections could be made to converge more quickly if the bandwidth of the X-rays were to be increased by a small amount or if a slight convergence angle were introduced into the incident beam. PMID:23793149

  4. 76 FR 78695 - Barry M. Schultz, M.D.; Decision and Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-19

    .... [See Michael G. Dolin, M.D., 65 FR 5,661 (DEA 2000); Jesus R. Juarez, M.D., 62 FR 14,945 (DEA 1997... 1 (citing 21 U.S.C. 801(21), 823(f), 824(a)(3); Layfe Robert Anthony, M.D., 67 FR 20,346 (2009... Roy Chi Lung, M.D., 74 FR 20,346 (2009); Michael Chait, M.D., 73 FR 40,382 (2008); Shahid...

  5. Localization of electrons and excitations

    NASA Astrophysics Data System (ADS)

    Larsson, Sven

    2006-07-01

    Electrons, electron holes, or excitations in finite or infinite 'multimer systems' may be localized or delocalized. In the theory of Hush, localization depends on the ratio Δ/ λ ( Δ/2 = coupling; λ = reorganization energy). The latter theory has been extended to the infinite system [S. Larsson, A. Klimkāns, Mol. Cryst. Liq. Cryst. 355 (2000) 217]. The metal/insulator transition often takes place abruptly as a function of Δ/ λ. It is argued that localization in a system with un-filled bands cannot be determined on the basis of Mott-Hubbard U alone, but depends on the number of accessible valence states, reorganization energy λ and coupling Δ (=2t). In fact U = 0 does not necessarily imply delocalization. The analysis here shows that there are many different situations for an insulator to metal transition. Charge transfer in doped NiO is characterized by Ni 2+ - Ni 3+ exchange while charge transfer in pure NiO is characterized by a disproportionation 2Ni 2+ → Ni + + Ni 3+. In spite of the great differences between these two cases, U has been applied without discrimination to both. The relevant localization parameters appear to be Δ and λ in the first case, with only two oxidation states, and U, Δ and λ in the second case with three oxidation states. The analysis is extended to insulator-metal transitions, giant magnetic resistance (GMR) and high Tc superconductivity (SC). λ and Δ can be determined quite accurately in quantum mechanical calculations involving only one and two monomers, respectively.

  6. Synthesis of SnTe nanoplates with {100} and {111} surfaces.

    PubMed

    Shen, Jie; Jung, Yeonwoong; Disa, Ankit S; Walker, Fred J; Ahn, Charles H; Cha, Judy J

    2014-07-01

    SnTe is a topological crystalline insulator that possesses spin-polarized, Dirac-dispersive surface states protected by crystal symmetry. Multiple surface states exist on the {100}, {110}, and {111} surfaces of SnTe, with the band structure of surface states depending on the mirror symmetry of a particular surface. Thus, to access surface states selectively, it is critical to control the morphology of SnTe such that only desired crystallographic surfaces are present. Here, we grow SnTe nanostructures using vapor-liquid-solid and vapor-solid growth mechanisms. Previously, SnTe nanowires and nanocrystals have been grown [Saghir et al. Cryst. Growth Des. 2014, 14, 2009-2013; Safdar et al. Cryst. Growth Des. 2014, 14, 2502-2509; Safdar et al. Nano Lett. 2013, 13, 5344-5349; Li et al. Nano Lett. 2013, 13, 5443-5448]. In this report, we demonstrate the synthesis of SnTe nanoplates with lateral dimensions spanning tens of micrometers and thicknesses of a few hundred nanometers. The top and bottom surfaces are either (100) or (111), maximizing topological surface states on these surfaces. Magnetotransport on these SnTe nanoplates shows a high bulk carrier density, consistent with bulk SnTe crystals arising due to defects such as Sn vacancies. In addition, we observe a structural phase transition in these nanoplates from the high-temperature rock salt to a low-temperature rhombohedral structure. For nanoplates with a very high carrier density, we observe a slight upturn in resistance at low temperatures, indicating electron-electron interactions.

  7. Optical influence of different standard illuminants on green nephrite's color From Manasi

    NASA Astrophysics Data System (ADS)

    Du, Hong-mei; Guo, Ying

    2010-11-01

    To evaluate the optical influence of illuminant on green color with low chroma (C*~1~12) of nephrite from Manasi, three different standard illuminant-daylight D65, incandescent light A and fluorescent light F2 (CWF) were applied during the experiment. Two-way ANOVA was used to analyze the illuminants tested considering the coordinates of lightness L* and chromaticity a*, b*. The results indicate significant differences for L*, a* and b* (p<0.05). Only L* between D65 and F2 didn't vary significantly (p=0.691) with the multiple comparisons (LSD- test). The green color with higher C*and L* were found to be easily influenced by illuminant, and the color-difference was larger and the color appearance varied more obviously while the illuminant as changed. The changes in color parameters and visual effects showed that the D65 light illuminant is more suitable for the evaluation of green nephrite's color grading while light source A can be used during trading.

  8. Illuminating light-dependent color shifts in core and veneer layers of dental all-ceramics

    NASA Astrophysics Data System (ADS)

    Lee, Yong-Keun; Cha, Hyun-Suk; Yu, Bin

    2014-09-01

    The color of an object is perceived differently depending on the ambient light conditions. Since dental all-ceramic restorations are fabricated by building up several layers to reproduce the tooth shade, the optical properties of each layer should be optimized for successful shade reproduction. This study aimed to determine the separate contributions of the color shifts in each of the core and veneer layers of all-ceramics by switching the illuminating lights on the color shifts of layered ceramics. Specimens of seven kinds of core ceramics and the corresponding veneer ceramics for each core were fabricated with a layered thickness of 1.5 mm. A sintering ceramic was used as a reference core material. The Commission Internationale de l'Eclairage (CIE) color coordinates of core, veneer, and layered specimens were measured with a spectroradiometer under the CIE illuminant D65 (daylight), A (incandescent lamp), and F9 (fluorescent lamp) simulating lights. Color shifts of the layered specimens were primarily determined by the CIE a* shifts (D65 to A switch) or by the CIE b* shifts (D65 to F9 switch) of the veneer layer. The color coordinates shifts in the constituent layers differentially influenced those of the layered specimens by the kind of switched lights. Therefore, the optical properties of the constituent layers of all-ceramics should be controlled to reflect these findings.

  9. Illuminating light-dependent color shifts in core and veneer layers of dental all-ceramics.

    PubMed

    Lee, Yong-Keun; Cha, Hyun-Suk; Yu, Bin

    2014-09-01

    The color of an object is perceived differently depending on the ambient light conditions. Since dental all-ceramic restorations are fabricated by building up several layers to reproduce the tooth shade, the optical properties of each layer should be optimized for successful shade reproduction. This study aimed to determine the separate contributions of the color shifts in each of the core and veneer layers of all-ceramics by switching the illuminating lights on the color shifts of layered ceramics. Specimens of seven kinds of core ceramics and the corresponding veneer ceramics for each core were fabricated with a layered thickness of 1.5 mm. A sintering ceramic was used as a reference core material. The Commission Internationale de l’Eclairage (CIE) color coordinates of core, veneer, and layered specimens were measured with a spectroradiometer under the CIE illuminant D65 (daylight), A (incandescent lamp), and F9 (fluorescent lamp) simulating lights. Color shifts of the layered specimens were primarily determined by the CIE a shifts (D65 to A switch) or by the CIE b shifts (D65 to F9 switch) of the veneer layer. The color coordinates shifts in the constituent layers differentially influenced those of the layered specimens by the kind of switched lights. Therefore, the optical properties of the constituent layers of all-ceramics should be controlled to reflect these findings.

  10. Bidirectional reflectance spectroscopy of carbonaceous chondrites: Implications for water quantification and primary composition

    NASA Astrophysics Data System (ADS)

    Garenne, A.; Beck, P.; Montes-Hernandez, G.; Brissaud, O.; Schmitt, B.; Quirico, E.; Bonal, L.; Beck, C.; Howard, K. T.

    2016-01-01

    In this study, we measured bidirectional reflectance spectra (0.5-4.0 μm) of 24 CMs, five CRs, one CI, one CV, and one C2 carbonaceous chondrites. These meteorites are known to have experienced an important variability in their relative degrees of aqueous alteration degree (Rubin et al. [2007]. Geochim. Cosmochim. Acta 71, 2361-2382; Howard et al. [2009]. Geochim. Cosmochim. Acta 73, 4576-4589; Howard et al. [2011]. Geochim. Cosmochim. Acta 75, 2735-2751; Alexander et al. [2013]. Geochim. Cosmochim. Acta 123, 244-260). These measurements were performed on meteorite powders inside an environmental cell under a primary vacuum and heated at 60 °C in order to minimize adsorbed terrestrial water. This protocol allows controlling of atmospheric conditions (i.e. humidity) in order to avoid contamination by terrestrial water. We discuss various spectral metrics (e.g. reflectance, band depth, single-scattering albedo, …) in the light of recent bulk composition characterization (Howard et al. [2009]. Geochim. Cosmochim. Acta 73, 4576-4589; Howard et al. [2015]. Geochim. Cosmochim. Acta 149, 206-222; Alexander et al. [2012]. Science 337, 721; Beck et al. [2014]. Icarus 229, 263-277; Garenne et al. [2014]. Geochim. Cosmochim. Acta 137, 93-112). This study reveals variability of reflectance among meteorite groups. The reflectance is not correlated with carbon or hydrogen abundance neither with measured grain size distribution. We suggest that it is rather controlled by the nature of accreted components, in particular the initial matrix/chondrule proportion. Band depth, integrated band depth, mean optical path length, normalized optical path length, effective single-particle absorption thickness were calculated on the so called 3-μm band for reflectance spectra and for single scattering albedo spectra. They were compared with hydrated phase proportions from previous study on the same meteorites by thermogravimetric analyses and infrared spectroscopy in transmission. We find

  11. Physicochemical aspects of reaction of ozone with galactolipid and galactolipid-tocopherol layers.

    PubMed

    Rudolphi-Skórska, Elżbieta; Filek, Maria; Zembala, Maria

    2014-07-01

    The impact of reaction of galactolipids with ozone on the physicochemical properties of their monolayers was examined. In Megli and Russo (Biochim Biophys Acta, 1778:143-152, 2008), Cwiklik and Jungwirth (Chem Phys Lett, 486:99-103, 2010), Jurkiewicz et al. (Biochim Biophys Acta, 1818:2388-2402, 2012), Khabiri et al. (Chem Phys Lett, 519:93-99, 2012), and Conte et al. (Biochim Biophys Acta, 1828:510-517, 2013), the properties of layers formed from model mixtures composed of chosen lipids and selected oxidation products were studied, whereas in this work, question was raised as to how the oxidation reactions taking place in situ affect the physical properties of the galactolipid layers. So, set experiment should take into account the effect of all reaction products. The mechanical characteristics of monolayers of monogalactosyldiacyl-glycerol (MGDG) and digalactosyldiacylglycerol (DGDG) were determined by Langmuir trough technique, and the electrical properties of liposomes formed from these lipids by measuring their electrophoretic mobility. Considerable loss of galactolipid molecules forming monolayers was found at ozone concentrations (in aqueous medium) higher than 0.1 ppm with a stronger effect measured for MGDG. That goes along with the greater amounts of MDA found in the extracts of oxidized MGDG films compared with DGDG. Based on this, it was concluded that an additional galactose group present in DGDG molecules acts protectively under oxidative conditions. The surface tension of the solutions (of small volume) contacting the oxidized galactolipids films was significantly reduced, indicating the presence of soluble in polar media, surface active reaction products. The presence of α-tocopherol in mixtures with tested galactolipids at a molar ratio of lipid to tocopherol equal to 1.7:1 caused some inhibition of lipid oxidation, reducing the decrease of amount of lipid particles forming the monolayer. Here, also protective effect of α-tocopherol was greater

  12. Nanoscale Structure at Mineral-Fluid Interfaces

    NASA Astrophysics Data System (ADS)

    Sturchio, N. C.; Sturchio, N. C.; Fenter, P.; Cheng, L.; Park, C.; Zhang, Z.; Zhang, Z.; Nagy, K. L.; Schlegel, M. L.

    2001-12-01

    The nature of nanoparticles and their role in the natural environment is currently a subject of renewed interest. The high surface area (and surface area-to-volume ratio) of nanoparticles exerts a widespread influence on geochemical reactions and transport processes. A thorough understanding of the nanoscale world remains largely hypothetical, however, because of the challenges associated with characterizing nanoscale structures and processes. Recent insights gained from high-resolution synchrotron x-ray reflectivity measurements at the solid-fluid interfaces of macroscopic (i.e., mm-scale) mineral particles may provide relevant guidelines for expected nanoparticle surface structures. For example, at calcite-water and barite-water interfaces, undercoordinated surface cations bond with water species of variable protonation, and modest relaxations (to several hundredths of a nanometer) affect the outermost unit cells [1,2]. Undercoordinated tetrahedral ions at aluminosilicate surfaces also bond with water species, whereas interstitial or interlayer alkali or alkaline earth ions at the surface may readily exchange with hydronium or other ions; modest relaxations also affect the outermost unit cells [3,4]. Modulation of liquid water structure out to about one nanometer has been observed at the (001) cleavage surface of muscovite in deionized water, and may be present at other mineral-fluid interfaces [4]. Dissolution mechanisms at the orthoclase-water interface have been clarified by combining x-ray reflectivity and scanning force microscopy measurements [5]. Further progress in understanding nanoscale structures and processes at macroscopic mineral-water interfaces is likely to benefit nanoparticle studies. [1] Fenter et al. (2000) Geochim. Cosmochim. Acta 64, 1221-1228. [2] Fenter et al. (2001) J. Phys. Chem. B 105(34), 8112-8119. [3] Fenter et al. (2000) Geochim. Cosmochim. Acta 64, 3663-3673. [4] Cheng et al. (2001) Phys. Rev. Lett., (in press). [5] Teng et al

  13. VizieR Online Data Catalog: The Green Bank Survey (Maslowski+ 1972-87)

    NASA Astrophysics Data System (ADS)

    Maslowski, J.

    1999-04-01

    This catalog presents the parts I, II, and III of the Green Bank survey of extragalactic radio sources at 1400 MHz. The data were obtained with the 300' antenna, producing a beamwidth of 10'x11' FWHM. Part I of the survey covers about 521 square degrees of the sky with RA from 7h17m to 16h23m, DEC from +45.8° to +51.7°. 1086 sources are presented down to a limiting flux density of 90 mJy. These data were originally published in Maslowski, 1972, Acta Astronomica, 22, 227 (1972AcA....22..227M). Part II of the survey covers 0.28 sr of the sky with RA from 7h08m to 16h57m, DEC from +31.9° to +39.7°. 2022 sources are presented down to a limiting flux density of 0.09 mJy. Spectral indices between 1400 MHz and 408 MHz are determined for most sources by comparison with the B2 source catalog (Cat.). These data were originally published in Machalski 1978, Acta Astronomica, 28, 367 (1978AcA....28..367M) Part III of the survey covers an area of 0.099 sr at declinations between 70 and 76.8 degrees. This catalog contains a total of 676 radio sources, of which 502 are statistically complete to 112 mJy. These data were originally published as Rys and Machalski, 1987, Acta Astronomica, 37, 163 (1987AcA....37..163R). (3 data files).

  14. A new calibration curve for carbonate clumped isotope thermometer of land snail shells (aragonite)

    NASA Astrophysics Data System (ADS)

    Zhang, N.; Yamada, K.; Yoshida, N.

    2013-12-01

    Clumped isotope data (Δ47) of carbonate is considered as a useful tool to reflect both the temperature and oxygen isotopic composition of water where the carbonate grew [1]. Zarrur et al. reported the relationship between snail shell calcification temperatures and the mean annual/ activity season ambient temperatures based on a calibration curve established by Ghosh et al. [2]. However, the clumped isotope temperature is always higher than the environment temperature. For better understanding this phenomenon, we present a new empirical calibration curve based on land snail shells (aragonite) cultured in the controlled temperature environment. In 2012, we cultured the land snails ';Euhadra' which were collected from Yokohama, Japan. They were cultured from eggs to adults around 6-8 months under the temperature of 20°, 25° and 30°, respectively. Each temperature group contains 15-20 snails. All of them were fed by cabbages during their life span. To study the effect of ingested carbonate, some of them were fed by Ca3(PO4)2 powder while others were fed by CaCO3 powder. Clumped isotope data for all samples were analyzed by a Thermo Finnigan MAT 253 Mass Spectrometer and calibrated by an ';absolute reference frame' [3]. We found an empirical linear relationship between Δ47 and controlled ambient temperature, which is slightly deviated from the published theoretical and experimental calibration curves based on both inorganic and biogenic materials. We will discuss the potential controlling factors caused this kind of deviation combine with the land snail growth environment. [1] Ghosh et al., 2006, Geochimica et Cosmochimica Acta. 70, 1439-1456 [2] Zaarur et al. 2011. Geochimica et Cosmochimica Acta, 75, 6859-6869 [3] Dennis et al., 2011. Geochimica et Cosmochimica Acta 75, 7117-7131

  15. Zebrafish models for nemaline myopathy reveal a spectrum of nemaline bodies contributing to reduced muscle function.

    PubMed

    Sztal, Tamar E; Zhao, Mo; Williams, Caitlin; Oorschot, Viola; Parslow, Adam C; Giousoh, Aminah; Yuen, Michaela; Hall, Thomas E; Costin, Adam; Ramm, Georg; Bird, Phillip I; Busch-Nentwich, Elisabeth M; Stemple, Derek L; Currie, Peter D; Cooper, Sandra T; Laing, Nigel G; Nowak, Kristen J; Bryson-Richardson, Robert J

    2015-09-01

    Nemaline myopathy is characterized by muscle weakness and the presence of rod-like (nemaline) bodies. The genetic etiology of nemaline myopathy is becoming increasingly understood with mutations in ten genes now known to cause the disease. Despite this, the mechanism by which skeletal muscle weakness occurs remains elusive, with previous studies showing no correlation between the frequency of nemaline bodies and disease severity. To investigate the formation of nemaline bodies and their role in pathogenesis, we generated overexpression and loss-of-function zebrafish models for skeletal muscle α-actin (ACTA1) and nebulin (NEB). We identify three distinct types of nemaline bodies and visualize their formation in vivo, demonstrating these nemaline bodies not only exhibit different subcellular origins, but also have distinct pathological consequences within the skeletal muscle. One subtype is highly dynamic and upon breakdown leads to the accumulation of cytoplasmic actin contributing to muscle weakness. Examination of a Neb-deficient model suggests this mechanism may be common in nemaline myopathy. Another subtype results from a reduction of actin and forms a more stable cytoplasmic body. In contrast, the final type originates at the Z-disk and is associated with myofibrillar disorganization. Analysis of zebrafish and muscle biopsies from ACTA1 nemaline myopathy patients demonstrates that nemaline bodies also possess a different protein signature. In addition, we show that the ACTA1(D286G) mutation causes impaired actin incorporation and localization in the sarcomere. Together these data provide a novel examination of nemaline body origins and dynamics in vivo and identifies pathological changes that correlate with muscle weakness. PMID:25931053

  16. Meta-analysis as Statistical and Analytical Method of Journal’s Content Scientific Evaluation

    PubMed Central

    Masic, Izet; Begic, Edin

    2015-01-01

    Introduction: A meta-analysis is a statistical and analytical method which combines and synthesizes different independent studies and integrates their results into one common result. Goal: Analysis of the journals “Medical Archives”, “Materia Socio Medica” and “Acta Informatica Medica”, which are located in the most eminent indexed databases of the biomedical milieu. Material and methods: The study has retrospective and descriptive character, and included the period of the calendar year 2014. Study included six editions of all three journals (total of 18 journals). Results: In this period was published a total of 291 articles (in the “Medical Archives” 110, “Materia Socio Medica” 97, and in “Acta Informatica Medica” 84). The largest number of articles was original articles. Small numbers have been published as professional, review articles and case reports. Clinical events were most common in the first two journals, while in the journal “Acta Informatica Medica” belonged to the field of medical informatics, as part of pre-clinical medical disciplines. Articles are usually required period of fifty to fifty nine days for review. Articles were received from four continents, mostly from Europe. The authors are most often from the territory of Bosnia and Herzegovina, then Iran, Kosovo and Macedonia. Conclusion: The number of articles published each year is increasing, with greater participation of authors from different continents and abroad. Clinical medical disciplines are the most common, with the broader spectrum of topics and with a growing number of original articles. Greater support of the wider scientific community is needed for further development of all three of the aforementioned journals. PMID:25870484

  17. Establishment of long-term monolayer cultures of somatic cells from human fetal testes and expansion of peritubular myoid cells in the presence of androgen.

    PubMed

    Cowan, Gillian; Childs, Andrew J; Anderson, Richard A; Saunders, Philippa T K

    2010-04-01

    The somatic (Sertoli cell (SC), Leydig cell (LC), and peritubular myoid (PTM) cell) cells play key roles in development of the fetal testis. We established monolayer cultures from second trimester human testes and investigated the pattern of expression of cell-lineage characteristic mRNAs. Expression of some SC-associated genes (SRY, SOX9, WT1, GATA4, and SF1) was detectable up to and including passage 3 (P3), while others (anti-Müllerian hormone; desert hedgehog) present prior to dissociation were not expressed in the cultured cells. Transcripts encoding the androgen receptor were expressed but addition of dihydrotestosterone (DHT) had no impact on expression of mRNAs expressed in SC or LC. Total concentrations of mRNAs encoding smooth muscle actin (ACTA2) and desmin increased from P1 to P3; an increasing proportion of the cells in the cultures were immunopositive for ACTA2 consistent with proliferation/differentiation of PTM cells. In conclusion, somatic cell monolayer cultures were established from human fetal testes; these cultures could form the basis for future studies based on isolation of purified populations of somatic cells and manipulation of gene expression that is difficult to achieve with organ culture systems. Our results suggest that fetal SC do not maintain a fully differentiated phenotype in vitro, yet PTM (ACTA2 positive) cells readily adapt to monolayer culture conditions in the presence of DHT. This culture system provides an opportunity to study the impact of regulatory factors on gene expression in PTM cells, a population thought to play a key role in mediating androgen action within the developing testis. PMID:20089665

  18. Second-order Optimality Conditions for Optimal Control of the Primitive Equations of the Ocean with Periodic Inputs

    SciTech Connect

    Tachim Medjo, T.

    2011-02-15

    We investigate in this article the Pontryagin's maximum principle for control problem associated with the primitive equations (PEs) of the ocean with periodic inputs. We also derive a second-order sufficient condition for optimality. This work is closely related to Wang (SIAM J. Control Optim. 41(2):583-606, 2002) and He (Acta Math. Sci. Ser. B Engl. Ed. 26(4):729-734, 2006), in which the authors proved similar results for the three-dimensional Navier-Stokes (NS) systems.

  19. Discovery of a meta-stable Al–Sm phase with unknown stoichiometry using a genetic algorithm

    SciTech Connect

    Zhang, Feng; McBrearty, Ian; Ott, R T; Park, E; Mendelev, Mikhail I; Kramer, M J; Wang, Cai-Zhuang; Ho, Kai-Ming

    2014-06-01

    Unknown crystalline phases observed during the devitrification process of glassy metal alloys significantly limit our ability to understand and control phase selection in these systems driven far from equilibrium. Here, we report a new meta-stable Al5Sm phase identified by simultaneously searching Al-rich compositions of the Al-Sm system, using an efficient genetic algorithm. The excellent match between calculated and experimental X-ray diffraction patterns confirms that this new phase appeared in the crystallization of melt-spun Al90Sm10 alloys. Published by Elsevier Ltd. on behalf of Acta Materialia Inc.

  20. [Infant-juvenile psychiatry in Algeria (author's transl)].

    PubMed

    Boucebci, M

    1977-01-01

    Psychiatric problems of the child and the adolescent in Algeria are discussed in light of traditional psycho-social factors and in the modern world. The emphasis is on the frequency and severity of troubles of organic origin. Parallely, the impact of new aspects, coming from consequences of socio-cultural mutations, is understressed. This study underlines relationships between psychiatric aspects and socio-economical and cultural factors, and the role of the psychiatrist, with the heavy responsabilities he has to face in all areas if he wants to remain in his therapeutic role (Acta psychiat. belg., 1977, 77, 587-622).

  1. A consistent quantum model for continuous photodetection processes

    NASA Astrophysics Data System (ADS)

    de Oliveira, M. C.; Mizrahi, S. S.; Dodonov, V. V.

    2003-06-01

    We modify some aspects of the continuous photodetection theory proposed by Srinivas and Davies (SD) (1981 Opt. Acta 28 981), which describes the non-unitary evolution of a quantum field state subjected to a continuous photocount measurement. In order to remedy inconsistencies that appear in their approach, we redefine the 'annihilation' and 'creation' operators that enter in the photocount super-operators. We show that this new approach not only still satisfies all the requirements for a consistent photocount theory according to SD precepts, but also avoids some weird result appearing when previous definitions are used.

  2. Statistical thermodynamics of strain hardening in polycrystalline solids.

    PubMed

    Langer, J S

    2015-09-01

    This paper starts with a systematic rederivation of the statistical thermodynamic equations of motion for dislocation-mediated plasticity proposed in 2010 by Langer, Bouchbinder, and Lookman [Acta Mat. 58, 3718 (2010)ACMAFD1359-645410.1016/j.actamat.2010.03.009]. It then uses that theory to explain the anomalous rate-hardening behavior reported in 1988 by Follansbee and Kocks and to explore the relation between hardening rate and grain size reported in 1995 by Meyers et al. A central theme is the need for physics-based, nonequilibrium analyses in developing predictive theories of the strength of polycrystalline materials.

  3. The publication of the astronomical observations of Buenaventura Suárez SJ (1679-1750) in European scientific journals

    NASA Astrophysics Data System (ADS)

    de Asúa, Miguel

    2004-12-01

    Many of the observations of Buenaventura Suárez (1679-1750), a Jesuit astronomer who worked in the missions of Paraguay, were made known in prestigious contemporary scientific European periodicals such as the Acta Societatis Regiae Scientiarum Upsalensis and the Philosophical Transactions of the Royal Society. Suarez recorded lunar and solar eclipses, and immersions and emersions of the satellites of Jupiter for the purpose of determining the longitude of the mission towns he lived in. He was able to keep abreast of the state of the field and communicate his results through the intermediacy of an epistolary net with correspondents in Europe and the New World.

  4. Magmas and their sources: A special issue honoring Frederick A. Frey

    NASA Astrophysics Data System (ADS)

    Garcia, Michael O.; Rhodes, J. Michael; Huang, Shichun; Hickey-Vargas, Rosemary

    2016-07-01

    This special issue is dedicated to Frederick A. Frey (Fig. 1), a pioneer in the use of trace element geochemistry (especially the rare-earth elements, REE) to interpret the origin and evolution of basalts and andesites, peridotites, granites, meteorites, tektites and even sediments. Fred's remarkable career spans more than 5 decades starting in 1964 with his seminal paper with advisor Larry Haskin entitled "rare earths in oceanic basalts" (Frey and Haskin, 1964). Given that Fred was an Associate Editor of Geochimica et Cosmochimica Acta (GCA) for 20 years, GCA is a highly appropriate venue for this collection of twenty-seven new scientific papers in his honor.

  5. On Iλ -statistical convergence of weight g

    NASA Astrophysics Data System (ADS)

    Savas, Ekrem

    2016-08-01

    In this paper, following a very recent and new approach of [M. Balcerzak, P. Das, M. Filipczak, and J. Swaczyna, Acta Math. Hungar. 147, 97-115 (2015)], we further generalize the recently introduced summability method of [E. Savas, and P. Das, Appl. Math. Lett. 24, 826-830 (2011)] and introduce the new notion namely, Iλ -statistical convergence of weight g, where g : ℕ → [0, ∞) is a function satisfying g(n) → ∞ and g(n) ↛ 0 as n → ∞. We mainly investigate certain properties of this convergence.

  6. Serum ornithine carbamoyltransferase (OCT) in rats poisoned with lanthanum, cerium and praseodymium.

    PubMed

    Marciniak, M; Bałtrukiewicz, Z

    1977-01-01

    Serum ornithine carbamoyltransferase (OCT) in rats poisoned with lanthanum, cerium and praseodymium. Acta Physiol. Pol., 1977, 28 (6): 589-594. The serum ornithine carbamoyltransferase in relation to doses of lanthanum, cerium and praseodymium, administered intravenously as chlorides, was investigated. A directly proportional relationship was found between the doses of these compounds and the serum enzyme level in rats. The lowest doses at which a rise in the serum OCT level occured were determined. They were: lanthanum - 0.75 mg/kg of body weight, cerium - 1.5 mg/kg, and praseodymium - 3 mh/kg. A decreasing toxicity of these elements with increasing value of atomic number was observed.

  7. Synthesis of (R)- and (S)- muscone.

    PubMed

    Fujimoto, Satoko; Yoshikawa, Keisuke; Itoh, Masamichi; Kitaharai, Takeshi

    2002-06-01

    (R)-(-)-Muscone (3-methylcyclopentadecanone, 1) the key perfumery component isolated from the male musk deer, Moschus moschiferus,* was synthesized from the easily available chiral building block, (R)-3-tert-butoxycarbonyl-2-methylpropanoic acid (2), by employing ring-closing olefin metathesis (RCM). Antipode (+)-1 was also synthesized in a similar manner from tert-butyl (S)-3-methoxycarbonylbutanoate (10). *(a) Walbaum, H. J. J. Prakt. Chem., 73, 488 (1906); (b) Ruzicka, L., Further considerations on the constitution of muscone. Helv. Chim. Acta, 9, 715, 1008-1017 (1926).

  8. PubMed Central

    2011-01-01

    Events for which complete information is available are listed in chronological order. Those taking place in Italy are in bold script. Information, following the style of the present list, should be submitted to the Editorial Secretariat of Acta Otorhinolaryngologica Italica. In accordance with the Regulations of S.I.O. and Ch.C.-F. (Art. 8) Members of the Society organising Courses, Congresses or other scientific events should inform the Secretary of the Association (A.U.O.R.L., A.O.O.I.) within the deadlines set down in the respective Statutes and Regulations.

  9. A possible role for acid phosphatase with thiamin-binding activity encoded by PHO3 in yeast.

    PubMed

    Nosaka, K; Kaneko, Y; Nishimura, H; Iwashima, A

    1989-07-01

    Periplasmic soluble thiamin-binding protein in Saccharomyces cerevisiae (Iwashima, A. et al. (1979) Biochim. Biophys. Acta 577, 217-220) was demonstrated to be encoded by PHO3 gene that codes for thiamin repressible acid phosphatase (Schweingruber, M.E. et al. (1986) J. Biol. Chem. 261, 15877-15882) by genetic analysis. The pho3 mutant cells of S. cerevisiae in contrast to the parent cells have markedly reduced activity of the uptake of [14C]thiamin phosphates, suggesting that thiamin repressible acid phosphatase plays a role in the hydrolysis of thiamin phosphates in the periplasmic space prior to the uptake of their thiamin moieties by S. cerevisiae.

  10. Mirror symmetry, chiral symmetry breaking, and antihydrogen states in natural atomic H

    NASA Astrophysics Data System (ADS)

    van Hooydonk, G.

    2002-10-01

    Molecular band spectra reveal a left-right symmetry for atoms [Van Hooydonk, Spectrochim. Acta A 56, 2273 (2000)]. Intra-atomic left-right symmetry points to antiatom states and, to make sense, this must also show in line spectra. H Lyman ns singlets show a mirror plane at quantum number n0=1/2π. A symmetry-breaking oscillator (1-1/2π/n)2 means that some of these n states are antihydrogenic. This view runs ahead of CERN's antiproton decelerator project on antihydrogen.

  11. GENERAL: Efficient quantum secure communication with a publicly known key

    NASA Astrophysics Data System (ADS)

    Li, Chun-Yan; Li, Xi-Han; Deng, Fu-Guo; Zhou, Hong-Yu

    2008-07-01

    This paper presents a simple way for an eavesdropper to eavesdrop freely the secret message in the experimental realization of quantum communication protocol proposed by Beige et al (2002 Acta Phys. Pol. A 101 357). Moreover, it introduces an efficient quantum secure communication protocol based on a publicly known key with decoy photons and two biased bases by modifying the original protocol. The total efficiency of this new protocol is double that of the original one. With a low noise quantum channel, this protocol can be used for transmitting a secret message. At present, this protocol is good for generating a private key efficiently.

  12. The electroanalytical approach to lipid peroxide determinations.

    PubMed

    Funk, M O

    1987-01-01

    An electroanalytical method for the determination of lipid peroxides in physiological material is described. The technique is based on electrochemical detection for HPLC as the means for enhancing sensitivity. Samples containing organic peroxides, including lipid peroxides, can be analyzed directly using a modified polarographic detector (Lloyd, J.B.F.; Optimization of the operational parameters of the supported mercury drop electrode detector in high performance liquid chromatography. Anal. Chim. Acta 154:121-131; 1983.) for reversed phase HPLC determinations. Detection limits for fatty acid hydroperoxides were found to be in the low nanogram range.

  13. A Multiparty Controlled Bidirectional Quantum Secure Direct Communication and Authentication Protocol Based on EPR Pairs

    NASA Astrophysics Data System (ADS)

    Chang, Yan; Zhang, Shi-Bin; Yan, Li-Li; Sheng, Zhi-Wei

    2013-06-01

    A multiparty controlled bidirectional quantum secure direct communication and authentication protocol is proposed based on EPR pair and entanglement swapping. The legitimate identities of communicating parties are encoded to Bell states which act as a detection sequence. Secret messages are transmitted by using the classical XOR operation, which serves as a one-time-pad. No photon with secret information transmits in the quantum channel. Compared with the protocols proposed by Wang et al. [Acta Phys. Sin. 56 (2007) 673; Opt. Commun. 266 (2006) 732], the protocol in this study implements bidirectional communication and authentication, which defends most attacks including the ‘man-in-the-middle’ attack efficiently.

  14. Group classification of Schrödinger equations with position dependent mass

    NASA Astrophysics Data System (ADS)

    Nikitin, A. G.; Zasadko, T. M.

    2016-09-01

    Maximal kinematical invariance groups of the 2d Schrödinger equations with position dependent mass (PDM) and arbitrary potential are classified. It is demonstrated that there exist seven classes of such equations possessing non-equivalent continuous symmetry group. Three of these classes include arbitrary functions while the remaining ones are defined up to arbitrary parameters. In particular, for the case of a constant mass the class missing in the Boyer classification (Boyer 1974 Helv. Phys. Acta. 47 450) is indicated. A constructive test of (non)equivalence of a PDM system to a constant mass system is proposed.

  15. Comparison of beetroot extracts originating from several sites using time-resolved laser-induced fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Rabasović, M. S.; Šević, D.; Terzić, M.; Marinković, B. P.

    2012-05-01

    Beetroot (Beta vulgaris) juice contains a large number of fluorophores which can fluoresce. There is a growing interest in beetroot extracts analysis. In contrast, there is only limited information about beetroot obtained without sample preparation and/or extraction of components from the sample. In this work, we continue our previous study (Rabasović et al 2009 Acta Phys. Pol. A 116 570-2), analyzing and comparing beetroot extracts from several sites, using the time-resolved laser-induced fluorescence technique to measure the fluorescence of samples at different excitation wavelengths (340-470 nm) and for different sample dilutions.

  16. An algorithm for emulsion stability simulations: account of flocculation, coalescence, surfactant adsorption and the process of Ostwald ripening.

    PubMed

    Urbina-Villalba, German

    2009-03-01

    The first algorithm for Emulsion Stability Simulations (ESS) was presented at the V Conferencia Iberoamericana sobre Equilibrio de Fases y Diseño de Procesos [Luis, J.; García-Sucre, M.; Urbina-Villalba, G. Brownian Dynamics Simulation of Emulsion Stability In: Equifase 99. Libro de Actas, 1(st) Ed., Tojo J., Arce, A., Eds.; Solucion's: Vigo, Spain, 1999; Volume 2, pp. 364-369]. The former version of the program consisted on a minor modification of the Brownian Dynamics algorithm to account for the coalescence of drops. The present version of the program contains elaborate routines for time-dependent surfactant adsorption, average diffusion constants, and Ostwald ripening.

  17. Method for measurement of diffusivity: Calorimetric studies of Fe/Ni multilayer thin films

    SciTech Connect

    Liu, JX; Barmak, K

    2015-07-15

    A calorimetric method for the measurement of diffusivity in thin film multilayers is introduced and applied to the Fe Ni system. Using this method, the diffusivity in [Fe (25 nm)/Ni (25 nm)](20) multilayer thin films is measured as 4 x 10(-3)exp(-1.6 +/- 0.1 eV/ k(B)T) cm(2)/s, respectively. The diffusion mechanism in the multilayers and its relevance to laboratory synthesis of L1(0) ordered FeNi are discussed. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  18. Use of an alumina column in estimating total iron-binding capacity.

    PubMed

    Starr, R T

    1980-01-01

    I describe a simple, rapid technique for saturating the transferrin in serum and then removing unbound (excess) iron. This technique involves use of an easily prepared column of basic chromatographic alumina and a saturating solution of ferric chloride in citric acid. This method, when compared with the magnesium carbonate method of Ramsay (Clin. Chim. Acta 2: 221, 1957) by regression analysis and tests of precision, showed a negative bias for results by the alumina technique with respect to the magnesium carbonate method. PMID:7356553

  19. Bipolaronic superconductivity

    NASA Astrophysics Data System (ADS)

    Alexandrov, A.; Ranninger, J.

    1981-08-01

    Superconducting properties of narrow-band electrons are examined in the strong-coupling limit. It is shown that bipolarons (localized spatially nonoverlapping Cooper pairs) formed by strong electron-phonon interaction have under certain conditions superconducting properties which are characteristic of superfluid charged Bose systems. They represent an example of the "molecular" superconductivity proposed by Schafroth, Butler, and Blatt

    [Helv. Phys. Acta 30 93 (1957)]
    . The Meissner effect and the penetration depth of bipolaronic superconductors are examined. The relationship between Bardeen-Cooper-Schrieffer superconductors and bipolaronic ones is discussed.

  20. Spherical nanoindentation stress-strain curves of commercially pure titanium and Ti-6Al-4V

    DOE Data Explorer

    Weaver, Jordan S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Priddy, Matthew W. [Georgia Inst. of Technology, Atlanta, GA (United States); McDowell, David L. [Georgia Inst. of Technology, Atlanta, GA (United States); Kalidindi, Surya R. [Georgia Inst. of Technology, Atlanta, GA (United States)

    2016-07-27

    Spherical nanoindentation combined with electron back-scattered diffraction was employed to characterize the grain-scale elastic and plastic anisotropy of single crystal alpha-Ti for commercially pure (CP-Ti) and alloyed (Ti-64) titanium. In addition, alpha-beta Ti (single colony) grains were characterized. The data set includes the nanoindentation force, displacement, and contact stiffness, the nanoindentation stress-strain analysis, and the alpha-Ti crystal orientations. Details of the samples and experimental protocols can be found in Weaver et al. (2016) Acta Materialia doi:10.1016/j.actamat.2016.06.053.

  1. The Oldest Recorded Case of Acromegaly and Gigantism in Iran.

    PubMed

    Najjari, Mohsen

    2015-10-01

    Here we commemorate the character and academic authority of Prof. Zabiholah Gorban (1903-2006), the founder of Shiraz medical school. No doubt, in the scope of history of contemporary medicine, he has been efficient and effective. With respect to this fact, his article on a rare case described in Acta anatomica published in Iran in 1966, entitled (Observations on a giant skeleton) is browsed and reviewed. A case named Siah Khan with combined acromegaly and gigantism that appears to have letters to say still after nearly half a century. PMID:26443258

  2. Improved method for measurement of inorganic phosphate in serum with a centrifugal analyzer.

    PubMed

    Wentz, P W; Savory, J; Cross, R E

    1976-02-01

    A direct mehtod [Clin. Chim. Acta 46, 113 (1973)] for determination of inorganic phosphate in serum was adapted for use with a centrifugal analyzer. Contamination is minimized and analysis rate maximized by doing the reaction in the reagent wells of the transfer disc and by utilizing the high-speed spectrophotometric and data-reduction capabilities of the centrifugal analyzer. Hemolysis, icterus, and moderate lipemia cause no interference. Grossly lipemic sera and sera from patients with plasma cell dyscrasias can be analyzed by incorporating appropriate blanking and dilution techniques. The method exhibits excellent sensitivity and precision and results correlate well with those from a continuous-flow procedure.

  3. Reaustenitization in Fe-C steels revisited

    SciTech Connect

    Mancini, R.; Budde, C.

    1999-08-10

    A finite difference method used in order to model the reaustenitization from a ferrite/cementite mixture in Fe-C steels is presented in this paper. The numerical results obtained are compared with the exact solution of the diffusion equion that describes the process for the planar geometry. The agreement between both methods is excellent in a large range of temperatures. Incidentally, the authors consider worth noting that the second moment of mass condition used by Akbay et al. [Acta Metallurgica et Materialia 47, 1649 (1994)] does not seem to be necessary in the framework of the numerical method. Finally, they compare their results with available experimental values finding good agreement.

  4. Gamma-ray tracking: Characterisation of the AGATA symmetric prototype detectors

    NASA Astrophysics Data System (ADS)

    Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Dimmock, M. R.; Nelson, L.; Nolan, P. J.; Rigby, S.; Lazarus, I.; Simpson, J.; Medina, P.; Santos, C.; Parisel, C.; AGATA Collaboration

    2007-08-01

    Each major technical advance in gamma-ray detection devices has resulted in significant new insights into the structure of atomic nuclei. The next major step in gamma-ray spectroscopy involves achieving the goal of a 4pi ball of Germanium detectors by using the technique of gamma-ray energy tracking in electrically segmented Germanium crystals. The resulting spectrometer will have an unparalleled level of detection power for nuclear electromagnetic radiation. Collaborations have been established in Europe (AGATA) [J. Simpson, Acta Phys. Pol. B 36 (2005) 1383. [1

  5. The Oldest Recorded Case of Acromegaly and Gigantism in Iran.

    PubMed

    Najjari, Mohsen

    2015-10-01

    Here we commemorate the character and academic authority of Prof. Zabiholah Gorban (1903-2006), the founder of Shiraz medical school. No doubt, in the scope of history of contemporary medicine, he has been efficient and effective. With respect to this fact, his article on a rare case described in Acta anatomica published in Iran in 1966, entitled (Observations on a giant skeleton) is browsed and reviewed. A case named Siah Khan with combined acromegaly and gigantism that appears to have letters to say still after nearly half a century.

  6. Isolation of monomeric photosystem II that retains the subunit PsbS.

    PubMed

    Haniewicz, Patrycja; De Sanctis, Daniele; Büchel, Claudia; Schröder, Wolfgang P; Loi, Maria Cecilia; Kieselbach, Thomas; Bochtler, Matthias; Piano, Dario

    2013-12-01

    Photosystem II has been purified from a transplastomic strain of Nicotiana tabacum according to two different protocols. Using the procedure described in Piano et al. (Photosynth Res 106:221-226, 2010) it was possible to isolate highly active PSII composed of monomers and dimers but depleted in their PsbS protein content. A "milder" procedure than the protocol reported by Fey et al. (Biochim Biophys Acta 1777:1501-1509, 2008) led to almost exclusively monomeric PSII complexes which in part still bind the PsbS protein. This finding might support a role for PSII monomers in higher plants.

  7. Generalization of color-difference formulas for any illuminant and any observer by assuming perfect color constancy in a color-vision model based on the OSA-UCS system.

    PubMed

    Oleari, Claudio; Melgosa, Manuel; Huertas, Rafael

    2011-11-01

    The most widely used color-difference formulas are based on color-difference data obtained under D65 illumination or similar and for a 10° visual field; i.e., these formulas hold true for the CIE 1964 observer adapted to D65 illuminant. This work considers the psychometric color-vision model based on the Optical Society of America-Uniform Color Scales (OSA-UCS) system previously published by the first author [J. Opt. Soc. Am. A 21, 677 (2004); Color Res. Appl. 30, 31 (2005)] with the additional hypothesis that complete illuminant adaptation with perfect color constancy exists in the visual evaluation of color differences. In this way a computational procedure is defined for color conversion between different illuminant adaptations, which is an alternative to the current chromatic adaptation transforms. This color conversion allows the passage between different observers, e.g., CIE 1964 and CIE 1931. An application of this color conversion is here made in the color-difference evaluation for any observer and in any illuminant adaptation: these transformations convert tristimulus values related to any observer and illuminant adaptation to those related to the observer and illuminant adaptation of the definition of the color-difference formulas, i.e., to the CIE 1964 observer adapted to the D65 illuminant, and then the known color-difference formulas can be applied. The adaptations to the illuminants A, C, F11, D50, Planckian and daylight at any color temperature and for CIE 1931 and CIE 1964 observers are considered as examples, and all the corresponding transformations are given for practical use.

  8. Effects of the International Temperature Scale of 1990 (ITS-90) on CIE documentary standards for radiometry, photometry, and colorimetry

    SciTech Connect

    Mielenz, K.D.; Hsia, J.J.

    1990-01-01

    The differences between ITS-90 and IPTS-68 (International Practical Temperature Scale of 1968) above 1235 K are described. It is shown that none of the following CIE (Commission Internationale de l'Eclairage or International Commission on Illumination) definitions or recommendations require revision because of the introduction of the ITS-90: International Lighting Vocabulary definitions; CIE Standard Illuminants A, D(65), other illuminants; and sources for realizing CIE Illuminants. The effect of the ITS-90 on previously calibrated sources for realizing CIE illuminants is negligibly small.

  9. DBI analog of a decaying vacuum cosmology

    NASA Astrophysics Data System (ADS)

    Bessada, Dennis

    2013-07-01

    In this work I discuss the dynamical and thermodynamical equivalence between a general k-essence scalar field cosmology and an arbitrary cosmological model with a decaying vacuum, thus generalizing the approach proposed by Maia and Lima [Phys. Rev. D 65, 083513 (2002)]. The formalism obtained is quite general and holds for any noncanonical scalar field model. As a special case I derive a Dirac-Born-Infeld model with an exponential potential and constant speed of sound, and show that it is equivalent to a cosmological model with decay law Λ(H)=3βH2.

  10. Schwinger pair production in electric and magnetic fields

    SciTech Connect

    Kim, Sang Pyo; Page, Don N.

    2006-03-15

    Charged particles in static electric and magnetic fields have Landau levels and tunneling states from the vacuum. Using the instanton method of Phys. Rev. D 65, 105002 (2002), we obtain the formulas for the pair-production rate in spinor and scalar QED, which sum over all Landau levels and recover exactly the well-known results. The pair-production rates are calculated for an electric field of finite extent, and for the Sauter potential, both with a constant magnetic field also present, and are shown to have finite-size effects.

  11. The Relationship Between the Color Characteristics of the RGB Colorimetric System and the Physicochemical Properties of Petroleums and high Boiling Hydrocarbon Distillates

    NASA Astrophysics Data System (ADS)

    Dolomatov, M. Yu.; Yarmuhametova, G. U.

    2016-09-01

    An interrelation was established between physicochemical properties of oils and high boiling hydrocarbon distillates and their solutions' color characteristics defi ned in the RGB colorimetric system using a standard radiation source CIE D65. It was shown that by using color characteristics of solutions of the specifi ed objects, it was possible to determine their relative density, molecular mass, activation energy of viscous fl ow, and the coking value. Research results were confi rmed by statistical data processing using the methods of multivariate regression and correlation analysis.

  12. Target binding to S100B reduces dynamic properties and increases Ca2+-binding affinity for wild type and EF-hand mutant proteins

    PubMed Central

    Liriano, Melissa A.; Varney, Kristen M.; Wright, Nathan T.; Hoffman, Cassandra L.; Toth, Eric A.; Ishima, Rieko; Weber, David J.

    2012-01-01

    Mutations in the second EF-hand (D61N, D63N, D65N, E72A) of S100B were used to study its Ca2+-binding and dynamic properties in the absence and presence of abound target, TRTK-12. With D63NS100B as an exception (D63NKD = 50 ± 9 µM), Ca2+-binding to EF2-hand mutants were reduced by more than 8-fold in the absence of TRTK-12 (D61NKD = 412 ± 67 µM; D65NKD = 968 ± 171 µM; E72AKD = 471 ± 133 µM), when compared to wild-type protein (WTKD = 56 ± 9 µM). For the TRTK-12 complexes, the Ca2+-binding affinity to wild type (WT+TRTKKD = 12 ± 10 µM) and the EF2 mutants were increased by 5- to 19-fold versus in the absence of target (D61N+TRTKKD = 29 ± 1.2 µM; D63N+TRTKKD = 10 ± 2.2 µM; D65N+TRTKKD = 73 ± 4.4 µM; E72A+TRTKKD = 18 ± 3.7 µM). In addition, Rex, as measured using relaxation dispersion for side chain 15N resonances of Asn63 (D63NS100B) was reduced upon TRTK-12 binding when measured by nuclear magnetic resonance (NMR). Likewise, backbone motions on multiple time scales (ps-ms) throughout wild type, D61NS100B D63NS100B, and D65NS100B were lowered upon binding TRTK-12. However, the X-ray structures of Ca2+-bound (2.0 Å) and TRTK-bound (1.2 Å) D63NS100B showed no change in Ca2+ coordination, so these and analogous structural data for the wild-type protein could not be used to explain how target binding increased Ca2+-binding affinity in solution. Thus, a model for how S100B-TRTK12 complex formation increases Ca2+ binding is discussed, which considers changes in protein dynamics upon binding the target TRTK-12. PMID:22824086

  13. Demonstration of a home projector based on RGB semiconductor lasers.

    PubMed

    Zhang, Yunfang; Dong, Hui; Wang, Rui; Duan, Jingyuan; Shi, Ancun; Fang, Qing; Liu, Yuliang

    2012-06-01

    In this paper, we demonstrate a high-definition 3-liquid-crystal-on-silicon (3-LCOS) home cinema projection system based on RGB laser source modules. Both red and blue laser modules are composed of an array of laser diodes, and the green laser is based on an optically pumped semiconductor laser. The illumination engine is designed to realize high energy efficiency, uniform illumination, and suppression of speckle noise. The presented laser projection system producing 1362 lm D65 light has a volume of about 450×360×160  mm3.

  14. Demonstration of a home projector based on RGB semiconductor lasers.

    PubMed

    Zhang, Yunfang; Dong, Hui; Wang, Rui; Duan, Jingyuan; Shi, Ancun; Fang, Qing; Liu, Yuliang

    2012-06-01

    In this paper, we demonstrate a high-definition 3-liquid-crystal-on-silicon (3-LCOS) home cinema projection system based on RGB laser source modules. Both red and blue laser modules are composed of an array of laser diodes, and the green laser is based on an optically pumped semiconductor laser. The illumination engine is designed to realize high energy efficiency, uniform illumination, and suppression of speckle noise. The presented laser projection system producing 1362 lm D65 light has a volume of about 450×360×160  mm3. PMID:22695597

  15. Cuticular Biominerals of the Terrestrial Crustacean Oniscus asellus (Isopoda, Linnaeus 1758)

    NASA Astrophysics Data System (ADS)

    Mergelsberg, S. T.; Mukhopadhyay, B.; Dove, P. M.

    2013-12-01

    F, Westbroek P et al., 1996, Proc Nat Acad Sci 93:1554-1559 Auzou G, 1953, L Ann Sci Nat 15:71-98 Ziegler A, 1997, Zoomorphology 117:181-187 Ziegler A et al., 2012, Cryst Growth Des 12:646-655 Keene EC et al., 2010, Cryst Growth Des 10:1383-1389

  16. Diagnosis and epidemiological association of Listeria monocytogenes strains in two outbreaks of listerial encephalitis in small ruminants.

    PubMed Central

    Wiedmann, M; Czajka, J; Bsat, N; Bodis, M; Smith, M C; Divers, T J; Batt, C A

    1994-01-01

    Two outbreaks of epizootic listerial encephalitis, one in sheep and one in goats, were investigated through pathology, microbiology, and DNA amplification-based techniques. Efforts were made to survey the diversity of Listeria monocytogenes strains in the silage consumed by affected animals and to verify the causal relationship between silage and disease outbreak. In both outbreaks, L. monocytogenes was isolated from silage and brain tissue samples. Random amplified polymorphic DNA patterns revealed two distinct L. monocytogenes strains, one of which was identical to the sheep brain isolate, in the silage associated with the outbreak in sheep. Three brain isolates and one silage isolate, all of which had different random amplified polymorphic DNA patterns, were found in the outbreak involving goats. All isolates from both outbreaks were indistinguishable in an in vitro assay for cell-to-cell spread and growth in macrophages. All brain isolates from the goat outbreak had identical intracellular ActA patterns, which were different from the pattern for the silage isolate. While the sheep brain isolate had an ActA pattern different from that of the corresponding silage isolate, the patterns for the brain isolates from the two outbreaks were not identical. This survey demonstrates the diversity of L. monocytogenes in silage and suggests the existence of one or more selective processes by which certain strains are more prone to give rise to disease. Images PMID:8027356

  17. An assessment of the accuracy of isochore location techniques for H 2O-CO 2-NaCl fluids at granulite facies pressure-temperature conditions

    NASA Astrophysics Data System (ADS)

    Johnson, Eric Lee

    1992-01-01

    Synthetic H 2O-CO 2-NaCl fluid inclusions with XCO2 compositions ranging from 0.10-0.51 and relative salinities ( r-s = wtNaCl/( wt NaCl + wt H 2O )) of 6 to 23.9 wt% have been produced in spontaneously nucleated forsterite, diopside, and orthopyroxene hosts. Molar volumes of the fluids at the pressure and temperature of formation have been calculated using microthermometric data from the fluid inclusions. These P- V- T data are used to compare the accuracy of published methods of isochore location for H 2O-CO 2-NaCl fluids at elevated pressures and temperatures. The results of these analyses show that isochores calculated with the MRK equation of BOWERS and HELGESON ( Geochim. Cosmochim. Acta, vol. 47, 1247-1275, 1983) reproduce the trapping pressures and temperatures well for fluids with XCO2 ≤ 0.3 and up to 23.9 wt% NaCl. For a fluid with XCO2 = 0.49 and relative salinity of 15%, however, the agreement is poor. For these fluid compositions, the observed molar volume is larger than that predicted from the MRK equation of Bowers and Helgeson and, if not corrected, will give isochores that are too low in pressure for a given temperature. The ideal geometric mixing model of BROWN and LAMB ( Geochim. Cosmochim. Acta, vol. 53, 1209-1221, 1989) provides less satisfactory results for the fluid compositions studied.

  18. Aspherical-atom modeling of coordination compounds by single-crystal X-ray diffraction allows the correct metal atom to be identified.

    PubMed

    Dittrich, Birger; Wandtke, Claudia M; Meents, Alke; Pröpper, Kevin; Mondal, Kartik Chandra; Samuel, Prinson P; Amin Sk, Nurul; Singh, Amit Pratap; Roesky, Herbert W; Sidhu, Navdeep

    2015-02-01

    Single-crystal X-ray diffraction (XRD) is often considered the gold standard in analytical chemistry, as it allows element identification as well as determination of atom connectivity and the solid-state structure of completely unknown samples. Element assignment is based on the number of electrons of an atom, so that a distinction of neighboring heavier elements in the periodic table by XRD is often difficult. A computationally efficient procedure for aspherical-atom least-squares refinement of conventional diffraction data of organometallic compounds is proposed. The iterative procedure is conceptually similar to Hirshfeld-atom refinement (Acta Crystallogr. Sect. A- 2008, 64, 383-393; IUCrJ. 2014, 1,61-79), but it relies on tabulated invariom scattering factors (Acta Crystallogr. Sect. B- 2013, 69, 91-104) and the Hansen/Coppens multipole model; disordered structures can be handled as well. Five linear-coordinate 3d metal complexes, for which the wrong element is found if standard independent-atom model scattering factors are relied upon, are studied, and it is shown that only aspherical-atom scattering factors allow a reliable assignment. The influence of anomalous dispersion in identifying the correct element is investigated and discussed. PMID:25393218

  19. Ultra High-Resolution In vivo Computed Tomography Imaging of Mouse Cerebrovasculature Using a Long Circulating Blood Pool Contrast Agent

    PubMed Central

    Starosolski, Zbigniew; Villamizar, Carlos A.; Rendon, David; Paldino, Michael J.; Milewicz, Dianna M.; Ghaghada, Ketan B.; Annapragada, Ananth V.

    2015-01-01

    Abnormalities in the cerebrovascular system play a central role in many neurologic diseases. The on-going expansion of rodent models of human cerebrovascular diseases and the need to use these models to understand disease progression and treatment has amplified the need for reproducible non-invasive imaging methods for high-resolution visualization of the complete cerebral vasculature. In this study, we present methods for in vivo high-resolution (19 μm isotropic) computed tomography imaging of complete mouse brain vasculature. This technique enabled 3D visualization of large cerebrovascular networks, including the Circle of Willis. Blood vessels as small as 40 μm were clearly delineated. ACTA2 mutations in humans cause cerebrovascular defects, including abnormally straightened arteries and a moyamoya-like arteriopathy characterized by bilateral narrowing of the internal carotid artery and stenosis of many large arteries. In vivo imaging studies performed in a mouse model of Acta2 mutations demonstrated the utility of this method for studying vascular morphometric changes that are practically impossible to identify using current histological methods. Specifically, the technique demonstrated changes in the width of the Circle of Willis, straightening of cerebral arteries and arterial stenoses. We believe the use of imaging methods described here will contribute substantially to the study of rodent cerebrovasculature. PMID:25985192

  20. Risk of bleeding after dentoalveolar surgery in patients taking anticoagulants.

    PubMed

    Broekema, Ferdinand I; van Minnen, Baucke; Jansma, Johan; Bos, Rudolf R M

    2014-03-01

    To avoid increasing the risk of thromboembolic events, it is recommended that treatment with anticoagulants should be continued during dentoalveolar operations. We have evaluated the incidence of bleeding after dentoalveolar operations in a prospective study of 206 patients, 103 who were, and 103 who were not, taking anticoagulants. Seventy-one were taking thrombocyte aggregation inhibitors and 32 vitamin K antagonists. Patients were treated according to guidelines developed at the Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands. The operations studied included surgical extraction (when the surgeon had to incise the gingiva before extraction), non-surgical extraction, apicectomy, and placement of implants. Patients were given standard postoperative care and those taking vitamin K antagonists used tranexamic acid mouthwash postoperatively. No patient developed a severe bleed that required intervention. Seven patients (7%) taking anticoagulants developed mild postoperative bleeds. Patients taking vitamin K antagonists reported 3 episodes (9%) compared with 4 (6%) in the group taking thrombocyte aggregation inhibitors. Among patients not taking anticoagulants, two (2%) developed mild bleeding. The differences between the groups were not significant. All bleeding was controlled by the patients themselves with compression with gauze. We conclude that dentoalveolar surgery is safe in patients being treated with anticoagulants provided that the conditions described in the ACTA guidelines are met. PMID:24485810