ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Digitale Medien

Fragment rotational distributions from the dissociation of NeBr2: Experimental and classical trajectory studies (1997)

Nejad-Sattari, Mehdi ; Stephenson, Thomas A.

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 106 (1997), S. 5454-5467

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: The Br2 fragment rotational distributions that result from the vibrational predissociation of NeBr2 in the B electronic state have been measured for several initial vibrational levels. In each case, the rotational distributions extend to the effective energetic limit determined by the amount of energy available (Eavl) for disposal into the fragment rotational and translational degrees of freedom. Analysis of the data allows refinement of the NeBr2 dissociation energy; we find that D0=70.0±1.1 cm−1 for the X electronic state, v=0. Both Δv=−1 and −2 dissociation events have been examined. For dissociation pathways with approximately the same value of Eavl the Δv=−2 pathways are observed to have a higher fraction of the fragment energy in rotational excitation. The overall shape of the Δv=−1 distributions are insensitive to the value of Eavl, suggesting that a Franck–Condon model for the dissociation may have some validity, though quantitative quantum mechanical calculations demonstrate that this model does not reproduce the large degree of fragment rotational excitation. Two classical models for the dissociation also fail to reproduce the extent of fragment rotational distribution. This result is discussed in light of previous experimental and theoretical investigations, focusing on the apparent agreement of classical models with the IBr fragment rotational distributions that result from the dissociation of NeIBr. © 1997 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.473570

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

2

Digitale Medien

Morphology of porous media studied by nuclear magnetic resonance (1997)

Allen, S. G. ; Stephenson, P. C. L. ; Strange, J. H.

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 106 (1997), S. 7802-7809

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: The filling processes of water and cyclohexane in porous silica (40 Å, 60 Å and 112 Å pore size samples) were studied using T2 nuclear magnetic resonance (n.m.r.) experiments. The silica pores contained water or cyclohexane and the experiments were performed at room temperature and at filling fractions ranging from 0.02 to 1.0 (that is, completely full). Two distinct processes were observed which depended on the hydrophilicity of the silica surface (or the surface adhesion of the liquid). Water was found to collect in small puddles in the silica interstices, and to form a surface layer over the silica before the remaining pore volume was filled. Water in a surface-treated porous silica and cyclohexane in regular porous silica appeared to completely fill the smaller before the larger pores, and not form a separate surface-coating layer. This work also presents the techniques used to calculate quantitative information about the filling process; specifically, determination of the volume to surface-area ratio of the liquid puddles as well as the number of these puddles, is demonstrated. © 1997 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.473780

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

3

Digitale Medien

Sedimentological responses to basin initiation in the Devonian of East Greenland (1997)

MARSHALL, J. E. A. ; STEPHENSON, B. J.

Oxford, UK : Blackwell Publishing Ltd

Sedimentology 44 (1997), S. 0

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1365-3091

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Geologie und Paläontologie

Notizen: The Devonian of East Greenland comprises a thick sequence of continental clastic sediments infilling an extensional basin. West of the main basin bounding fault (Western Fault Zone) are scattered outliers of Devonian conglomerate which accumulated in small basins such as found on the island, Ella Ø. The Ella Ø Basin formed by extensional movement along the Narhval Sund Fault accompanied by the formation of a prominent bedding parallel detachment surface which was subsequently modified by sub-aerial exposure to become the unconformity surface. Mapping of this unconformity surface shows major vertical relief. A thick sequence of conglomerate occurs on Ella Ø, which, close to its exposed basal unconformity, has three lacustrine beds intercalated within it. Detailed analysis of one lake unit shows it to have significant lateral variation. At proximal localities it largely comprises lacustrine turbidites, whereas more distal locations were within a stratified lake. The interpreted sequence of events on Ella Ø is an interval of fluvial sedimentation followed by rapid drowning of the topography with lacustrine sediments onlapping onto basement. After an interval of deeper lacustrine sedimentation including laminites, the lake shallowed, the lithology changed to limestone and the lake dried out. Conglomerate deposition then recommenced. Maximum lake water depth of 100 m is estimated following correction (7°) for post-Devonian rotation, both determined using the distribution of lacustrine sediments on the unconformity surface. The preferred mechanism for flooding of the Ella Ø Basin is episodic flooding of the entire basin system. Lacustrine sediment preservation results purely from its deposition amongst topography at the edge of the active fluvial system. In such fluvial systems lacustrine sediments may be part of the normal sedimentary cycle but were almost always removed by reworking.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1046/j.1365-3091.1997.d01-29.x

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

4

Digitale Medien

The Fate of Heavy Metals in Pilot-Plant Scale Upflow Sludge-Blanket Clarifiers (1987)

HUNTER, M. ; STEPHENSON, T. ; LESTER, J. N.

Oxford, UK : Blackwell Publishing Ltd

Water and environment journal 1 (1987), S. 0

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1747-6593

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Energietechnik

Notizen: The Removal of heavy metals and aluminium residuals during upflow sludge-blanket clarification was investigated using a pilot-plant system. Pilot units treating predosed raw water on site were assessed for sludge-blanket formation and stabilization, and were found to produce clarified water of a comparable quality to the main works units after the start-up and stabilization periods were complete. The heavy metals Cr, Fe, Mn, and Ni were the only heavy metals detectable at the investigation site and these occurred at concentrations well below guidelines values for potable abstraction and supply.Mean removals of Fe, Mn, Cr, and Ni were about 98, 89, 51, and 30 per cent respectively, during steady-state operation, and Fe, Mn, and Cr all displayed reduced removals during transient changes in surface load, whereas Ni removal appeared to be relatively independent. Aluminium residuals derived from the dosed alum coagulant also showed decreases in removal from about 83 per cent during steady-state operation to between 40 and 50 per cent during transient experiments.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1747-6593.1987.tb01192.x

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

5

Digitale Medien

Numerical methods for heat transfer in hydraulic fracturing (1987)

Bennaceur, K. ; Dunand, A. ; Stephenson, P.

Chichester [u.a.] : Wiley-Blackwell

International Journal for Numerical Methods in Engineering 24 (1987), S. 75-87

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 0029-5981

Schlagwort(e): Engineering ; Engineering General

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Mathematik , Technik allgemein

Notizen: During the propagation of a hydraulically induced fracture in a porous material, fluid leak-off occurs from the fracture to the formation. Conduction and convection of heat also take place, owing to the large difference between the fluid injection temperature and that of the reservoir. The paper describes a quasi-two-dimensional heat transfer model coupled with a filtration model. It is then coupled into different coupled fracture propagation models (two-dimensional and quasi-three-dimensional).The rheological characteristics of the fracturing fluid are temperature-dependent with a sharp breakdown. The fluid diffusion model combines cake growth at the fracture face with two-fluid flow in the formation. Temperature profiles along the fracture and the formation are computed during fracture propagation.

Zusätzliches Material: 11 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/nme.1620240106

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

6

Digitale Medien

Estimation of the speed of propagation of intergranular stress waves using a simple elastic contact model (1987)

Stephenson, Stuart E.

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 27 (1987), S. 1310-1316

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 0032-3888

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: A model of a granular bed is used to obtain an estimate of the speed of propagation of intergranular stress waves. In the analysis, a simple elastic contact between neighboring grains is assumed. The model may be extended to include more complex Intergranular interaction mechanisms, but at the expense of such a simple analytical solution as that obtained here. The predicted dependence of compression of a granular bed on compressive load is compared with experimental measurements and is found to describe the relationship very well. The simplified analysis gives a general insight into the dependency of wave speed on bed geometry, indicating for example that while wave speed is independent of grain size, it does depend on the Initial porosity of the bed.

Zusätzliches Material: 3 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pen.760271707

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

7

Digitale Medien

High-order methods for elliptic equations with variable coefficientsThis research is supported by the National Science and Engineering Research Council of Canada operating Grants No. 3054 and No. A 5418. (1987)

Ananthakrishnaiah, U. ; Manohar, R. ; Stephenson, J. W.

New York, NY [u.a.] : Wiley-Blackwell

Numerical Methods for Partial Differential Equations 3 (1987), S. 219-227

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 0749-159X

Schlagwort(e): Mathematics and Statistics ; Numerical Methods

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Mathematik

Notizen: In this article, we give a simple method for developing finite difference schemes on a uniform square gird. We consider a general, two-dimensional, second-order, partial differential equation with variable coefficients. In the case of a nine-point scheme, we obtain the known results of Young and Dauwalder in a fairly elegant fashion. We show how this can be extended to obtain fourth-order schemes on thirteen points. We derive two such schemes which are attractive because they can be adapted quite easily bnto obtain formulas for gird points near the boundary. In addition to this, these formulas only require nine evaluations for the typical forcing function. Numerical examples are given to demonstrate the performance of one of the fourth-order schemes.

Zusätzliches Material: 1 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/num.1690030306

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

8

Digitale Medien

Fourth-order finite difference methods for three-dimensional general linear elliptic problems with variable coefficientsThis research is supported by the National Science and Engineering Council of Canada operating Grants No. A 3050 and No. A 5418. (1987)

Ananthakrishnaiah, U. ; Manohar, R. ; Stephenson, J. W.

New York, NY [u.a.] : Wiley-Blackwell

Numerical Methods for Partial Differential Equations 3 (1987), S. 229-240

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 0749-159X

Schlagwort(e): Mathematics and Statistics ; Numerical Methods

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Mathematik

Notizen: In this article, we give a simple method for deriving finite difference schemes on a uniform cubic grid. We consider a general, three-dimensional, second-order, linear, elliptic partial differential equation with variable coefficients. We derive two simple fourth-order schemes. When the coefficients of the second-order mixed derivatives are equal to zero, the fourth-order scheme requires only 19 grid points. When the coefficients of the mixed derivatives are not equal to zero and the coefficients of Uxx, Uyy, and Uzz are equal, we require the 27 points of the cubic grid. Numerical examples are given to demonstrate the performance of the two schemes derived. There does not exist a fourth-order scheme involving 27 grid points for the general case.

Zusätzliches Material: 1 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/num.1690030307

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

9

Digitale Medien

Study of the monomer-dimer equilibrium of nitrosobenzene using multinuclear one- and two-dimensional NMR techniques (1987)

Orrell, Keith G. ; Šik, Vladimir ; Stephenson, David

Chichester : Wiley-Blackwell

Organic Magnetic Resonance 25 (1987), S. 1007-1011

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 0749-1581

Schlagwort(e): 13C ; 15N ; 17O NMR 13C ; 2D-EXSY ; nitrosobenzene ; activation energies ; Chemistry ; Analytical Chemistry and Spectroscopy

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The monomer-dimer equilibrium of nitrosobenzene in CDCI3 solution was studied in the temperature range -50 to 30 °C using 13C, 15N and 17O NMR spectroscopy. Decreasing temperature favours the dimeric azodioxy species, and below ca 10 °C both cis and trans dimers were detected in addition to the monomer. The relative abundance of the trans dimer is low (≤6%) at all temperatures and this is the first report of its existence in solution. The monomer and dimer species were characterized by their 13C and 15N shifts, and exchange between them was measured quantitatively by 13C 2D-EXSY spectra. Exchange occurred exclusively between the cis-dimer and monomer and between the trans-dimer and monomer, activation energies, ΔG≠(298.15 K) being 65.8±0.1 and 70.0±0.3 kJ mol-1, respectively.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/mrc.1260251118

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

10

Unbekannt

Skeletal muscle as the potential power source for a cardiovascular pump: assessment in vivo (1987)

M. A. Acker ; R. L. Hammond ; J. D. Mannion ; [weitere]

American Association for the Advancement of Science (AAAS)

In: Science. 236(4799): 324-7.

zur Merkliste hinzufügen auf der Merkliste

Details

Publikationsdatum: 1987-04-17

Beschreibung: Skeletal muscle ventricles (SMVs) were constructed from canine latissimus dorsi and connected to a totally implantable mock circulation device. The SMVs, stimulated by an implantable pulse generator, pumped continuously for up to 8 weeks in free-running beagle dogs. Systolic pressures produced by the SMVs, initially of 139 +/- 7.2 mmHg and after 1 month of continuous pumping of 107 +/- 7 mmHg, were comparable to normal physiologic pressures in the adult beagles (114 +/- 21 mmHg). After 2 weeks of continuous pumping, the mean stroke work of the SMVs was 0.4 X 10(6) ergs, a performance that compares favorably with the animal's cardiac ventricles. This study shows that canine skeletal muscle which has not received prior training or electrical conditioning can perform sustained work at the high levels needed for an auxiliary cardiovascular pump. It might be possible eventually to use such muscle pumps in humans to assist the failing circulation and to provide support in children with certain types of congenital heart defects.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Acker, M A -- Hammond, R L -- Mannion, J D -- Salmons, S -- Stephenson, L W -- HLBI 34778/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1987 Apr 17;236(4799):324-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2951849" target="_blank"〉PubMed〈/a〉

Schlagwort(e): Adenosine Triphosphatases/metabolism ; Animals ; Blood Circulation ; Blood Pressure ; *Cardiovascular Physiological Phenomena ; Dogs ; Kinetics ; Models, Biological ; Muscles/enzymology/*physiology ; Myosins/metabolism

Print ISSN: 0036-8075

Digitale ISSN: 1095-9203

Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik

Publiziert von American Association for the Advancement of Science (AAAS)

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

AKTUELLE ARTIKEL

S·F·X

Volltext