Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Internal molecular vibrations from crystal diffraction data by quasinormal mode analysis (1985)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 41 (1985), S. 244-251 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The established procedure for analyzing molecular vibrations in terms of normal modes has been adapted so that experimental anisotropic thermal parameters can be used to study low-frequency internal vibrations of simple molecules in crystals. This involves quasinormal modes, which are linear combinations of selected low-frequency internal modes such as the torsional librations about individual bonds. Higher-frequency modes are neglected, since their contribution to the atomic mean-square displacements should be small. The force constants for selected low- frequency internal modes, together with the tensor components (T,L,S) that describe the overall molecular vibration, become the variables in an iterative least-squares refinement in which the observations are the atomic Uij values. As a result, the concerted motion of the atoms for each quasinormal mode is defined and also its vibrational frequency. Corrections to bond lengths and angles due to internal vibrations can be calculated. In tests involving two different lipid crystal structures, the internal motions were introduced as torsions about two or three bonds occurring near the junction of an extended hydrocarbon chain with a relatively rigid massive atomic grouping. Compared with the simple rigid-body model, there were highly significant improvements in agreement between experimental and calculated Uij values. Force constants for torsion about three C-S bonds were also in agreement [26 (5), 23 (6) and 22 (6) J mol-1 deg-2]. In one of the crystal structures (determined at 123 K), the six C-C bonds of a paraffin chain have average lengths 1.526 (2) Å before correction, 1.527 (3) Å after correction for simple rigid-body libration and 1.536 (4) Å after corrections including the quasinormal vibrations. The latter agrees with the electron diffraction value 1.542 (4) Å for n-hexadecane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767385000538
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Full-matrix inversion procedure for minimum-variance Fourier coefficient (MVFC) refinement (1989)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 45 (1989), S. 308-308 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A fast matrix inversion procedure is suggested for matrices containing a large diagonal block as is the case in minimum- variance Fourier coefficient refinement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S010876738801311X
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Heat capacity of hydrogenated diamond-like carbon films (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2340-2342 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used differential scanning calorimetry to measure the heat capacity of diamond-like carbon (DLC) film prepared by a plasma immersion ion processing method. The same calorimeter was used to measure the heat capacity of single crystal natural diamond and of high purity graphite. The amount of atomic hydrogen trapped in the DLC films was determined by elastic-recoil-detection spectrometry. The present data and literature values were used to deduce an expression for the specific heat that factors out the contribution from the sp3/sp2 bonding and from the atomic hydrogen trapped in the carbon. The data shows that the hydrogen contribution to the specific heat of carbon is independent of the sp3/sp2 bonding and amounts to about 0.63kB per hydrogen atom. We propose a simple method to determine the sp3/sp2 bonding ratio in hydrogenated DLC films based on measuring the specific heat and the hydrogen content of the sample. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1290387
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Diamondlike carbon deposition on silicon using radio-frequency inductive plasma of Ar and C2H2 gas mixture in plasma immersion ion deposition (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2423-2425 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamondlike carbon (DLC) was deposited on silicon using a plasma immersion ion deposition (PIID) method. Inductive radio-frequency plasma sources were used to generate Ar and C2H2 plasmas at low gas pressures ranging from 0.04 to 0.93 Pa. The film stress and hardness were sharply dependent upon bias voltage at an operating pressure of 0.04 Pa. A maximum hardness of 30 GPa and compressive stress of 9 GPa was observed at a pulsed bias of −150 V bias (carbon energy of 80 eV). The mechanical properties of DLC films are correlated with UV Raman peak positions which infer sp3-bonded carbon contents. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122469
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Protein crystal growth aboard the U.S. space shuttle flights STS-31 and STS-32
    Amsterdam : Elsevier
    Advances in Space Research 12 (1992), S. 393-400 
    Details
    ISSN: 0273-1177
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0273-1177(92)90310-T
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    A comparison between protein crystals grown with vapor diffusion methods in microgravity and protein crystals using a gel liquid-liquid diffusion ground-based method
    Amsterdam : Elsevier
    Journal of Crystal Growth 122 (1992), S. 306-309 
    Details
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0022-0248(92)90261-G
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Thermal vibrations and electrostatic properties of parabanic acid at 123 and 298 K (1988)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 44 (1988), S. 271-281 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768187011108
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Internal vibrations of a molecule consisting of rigid segments. I. Non-interacting internal vibrations (1993)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 49 (1993), S. 10-22 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: For molecular crystals, a procedure is proposed for interpreting experimentally determined atomic mean square anisotropic displacement parameters (ADPs) in terms of the overall molecular vibration together with internal vibrations with the assumption that the molecule consists of a set of linked rigid segments. The internal librations (molecular torsional or bending modes) are described using the variable internal coordinates of the segmented body. In paper I of this two-part report, it is assumed as a zero-order approximation that the internal vibrations about the linkage axes between pairs of segments are uncorrelated with each other and with the overall molecular rigid-body vibrations. As a first-order approximation, the possibility that each internal vibration can be correlated with the external vibrations is also considered. An important feature of this approach is that the internal librations are required to give zero contribution to the overall momentum of the molecule at all times, so the internal coordinates must be orthogonai to the external ones. Also, each of the internal librations involves the motion of all atoms in the molecule. The resulting internal vibrational parameters are invariant to the choice of reference segment. With this procedure, the experimental ADPs obtained from crystal structure determinations involving six small molecules (sym-trinitrobenzene, adenosine, tetracyanoquinodimethane, benzamide, α-cyanoacetic acid hydrazide and N-acetyl-L-tryptophan methylamide) have been analyzed. As a consequence, vibrational corrections to the bond lengths and angles of the molecule are calculated as well as the frequencies and force constants (with e.s.d.'s) for each internal torsional or bending vibration. Compared with other models used for describing internal vibrations, there are differences in how the total ADP is partitioned between the internal and overall molecular vibrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767392005245
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Differences in crystal properties and ligand affinities of an antifluorescyl fab (4-4-20) in two solvent systems (1988)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 3 (1988), S. 155-160 
    Details
    ISSN: 0887-3585
    Keywords: monoclonal antibodies ; high-affinity combining sites ; MPD ; Effects of fluorescein binding ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: An antigen-binding fragment (Fab) from a murine monoclonal antibody (4-4-20) with high affinity for fluorescein was cocrystallized with ligand in polyethylene glycol (PEG) and 2-methl-2,4-pentanediol (MPD) in forms suitable for X-ray analyses. In MPD the affinity of the intact antibody for fluorescein was 300 times lower than the value (3.4 × 1010 M-1) obtained in aqueous buffers. This decreased affinity was manifested by the partial release of bound fluorescein when MPD was added to solutions of liganded Feb during crystallization trials, In PEG, the ligand remained firmly bound to the protein. The liganded Feb crystallized in the monoclinic space group P21 in PEG, with a = 58.6, b = 97.2, c = 44.5 Å and β = 95.2°. In MPD the space group was triclinic P1, with a = 58.3, b = 43.4, c = 42.3 Å, α = 83.9°, β = 87.6°, and γ = 84.5°. X-ray diffraction data were collected for both forms to 2.5-Å resolution. Surprisingly, the triclinic form of the liganed antifluorescyl Feb had the same space group, closely similar cell dimensions, and practically the same orientation in the unit cell as an unliganded Fab (BV04-01) with activity against single-stranded DNA.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340030304
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    An autoantibody to single-stranded DNA: Comparison of the three-dimensional structures of the unliganded fab and a deoxynucleotide-fab complex (1991)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 11 (1991), S. 159-175 
    Details
    ISSN: 0887-3585
    Keywords: anti-ss-DNA autoantibody ; deoxynucleotide-Fab complex ; conformational changes in protein when ligand is bound ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Crystal structures of the Fabs from an autoantibody (BV04-01) with specificity for single-stranded DNA have been determined in the presence and absence of a trinucleotide of deoxythymidylic acid, d(pT)3. Formation of the ligand-protein complex was accompanied by small adjustments in the orientations of the variable (VL and VH) domains. In addition, there were local conformational changes in the first hypervariable loop of the light chain and the third hypervariable loop of the heavy chain, which together with the domain shifts led to an improvement in the complementarity of nucleotide and Fab. The sugar-phosphate chain adopted an extended and “open” conformation, with the base, sugar, and phosphate components available for interactions with the protein. Nucleotide 1 (5′-end) was associated exclusively with the heavy chain, nucleotide 2 was shared by both heavy and light chains, and nucleotide 3 was bound by the light chain. The orientation of phosphate 1 was stabilized by hydrogen bonds with serine H52a and asparagine H53. Phosphate 2 formed an ion pair with arginine H52, but no other charge-charge interactions were observed. Insertion of the side chain of histidine L27d between nucleotides 2 and 3 resulted in a bend in the sugar-phosphate chain. The most dominant contacts with the protein involved the central thymine base, which was immobilized by cooperative stacking and hydrogen bonding interactions. This base was intercalated between a tryptophan ring (no. H100a) from the heavy chain and a tyrosine ring (no. L32) from the light chain. The resulting orientation of thymine was favorable for the simultaneous formation of two hydrogen bonds with the backbone carbonyl oxygen and the side chain hydroxyl group of serine L91 (the thymine atoms were the hydrogen on nitrogen 3 and keto oxygen 4).
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340110302
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...