Radialverfahren zur Ausführung der Elektrophorese und der Elektrorheophorese auf Papier

Zusammenfassung Die theoretische Bearbeitung des elektrophoretischen und des elektrorheophoretischen Radialverfahrens und die experimentelle Überprüfung der Resultate zeigen, daß es unter Verwendung des von uns vorgeschlagenen und beschriebenen Apparates möglich ist, für jede Substanz einen charakteristischen Index der elektrophoretischen Beweglichkeit zu bestimmen. Dieser Index erlaubt den Nachweis der betreffenden Substanz.

---

Summary The theoretical treatment of the electrophoretic and the electrorheophoretic radial process and the experimental checking of the results show that by employing the apparatus suggested and described by the authors it is possible to determine for each substance a characteristic index of electrophoretic mobility. This index permits the identification of the substance in question.

---

Résumé L'étude théorique de la méthode d'électrophorèse et d'électrorhéophorèse radiales et le contrôle expérimental des résultats obtenus montrent qu'en employant l'appareil que nous avons recommandé et décrit, il est possible De déterminer pour chaque substance un indice caractéristique de la mobilité électrophorétique. Cet indice permet l'identification de la substance considérée.

     

Some remarks on continuous dependence and uniqueness in finite elastostatics for unbounded domains

Summary In connection with a foregoing paper, in the present note we establish some continuous dependence and uniqueness theorems for classical solutions to the equilibrium problem of finite elasticity. The elastic body is supposed to fill an unbounded domain of the physical space. We employ the weight function method and a suitable extension to the non-linear case of a method previously introduced by other authors for the linear case.

---

Sommario In connessione con un precedente lavoro, si dimostrano nella presente nota alcuni teoremi di dipendenza continua ed unicità per soluzioni classiche del problema statico non lineare relativo ad un corpo elastico occupante un dominio illimitato dello spazio fisico. Vengono adoperati il metodo della funzione peso e l'estensione al caso non lineare di un metodo precedentemente introdotto da altri autori per il caso lineare.

---

---

Work performed under the auspices of G.N.F.M. of the Italian Research Council (C.N.R.).     

Glass transition in biomolecules and the liquid-liquid critical point of water

Using molecular dynamics simulations, we investigate the relation between the dynamic transitions of biomolecules (lysozyme and DNA) and the dynamic and thermodynamic properties of hydration water. We find that the dynamic transition of the macromolecules, sometimes called a "protein glass transition," occurs at the temperature of dynamic crossover in the diffusivity of hydration water and also coincides with the maxima of the isobaric specific heat C_{P} and the temperature derivative of the orientational order parameter. We relate these findings to the hypothesis of a liquid-liquid critical point in water. Our simulations are consistent with the possibility that the protein glass transition results from crossing the Widom line, which is defined as the locus of correlation length maxima emanating from the hypothesized second critical point of water.     

Structure of sodium glycodeoxycholate micellar aggregates from small-angle X-ray scattering and light-scattering techniques

Small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS) measurements were accomplished on sodium glycodeoxycholate (NaGDC) aqueous electrolyte solutions as a function of NaGDC and NaCl concentrations with the aim to determine with satisfactory approximation the NaGDC micellar aggregate structure at a gross molecular level, assuming monodispersity. Different conditions of interparticle interactions by varying ionic strength (NaCl concentration from 0 to 0.70 M) and NaGDC concentration (from 0.02 to 0.10 M) were studied. Smeared scattering intensities and electron pair distance distribution functions, radii of gyration, and aggregate heights are in satisfactory agreement with the corresponding functions calculated using a 2(1) helix as model. It is formed by trimers, each one composed by three NaGDC and nine H2O molecules related by a 3-fold rotation axis, and can be described by a hollow cylinder, probably filled by water molecules, characterized by a conventional radius of 23.7 A and a trimer repeat along the helical axis of 3.6 A. The helix is considerably inhomogeneous since the volume of the cylinder occupied by NaGDC molecules is less than one-third of the total. On the other hand, calculations performed with the average radial electronic density of the helix without water molecules or totally filled by water molecules (a NaGDC/H2O molecular ratio of about 1/50) or by using a three-shell average radial electronic density, independently evaluated on absolute scale, do not show significant differences, thus supporting the helical model. The aggregate size increases for all the samples by increasing either the NaCl or NaGDC concentration. The NaGDC low concentration (0.02 M) samples with NaCl within the range 0.30-0.70 M are characterized by short cylindrical aggregates that do not give rise to sensible interference effects. This assertion is supported by the satisfactory fit between the observed apparent mean hydrodynamic radii and the calculated ones by means of the method of Ortega and Garcia de la Torre (J. Chem. Phys. 2003, 119, 9914), valid for rods with a length-to-diameter ratio > or = 0.1 in dilute solution (noninteracting rods). The NaGDC moderate concentration (0.10 M) samples with NaCl within the range 0.20-0.60 M are characterized by cylindrical aggregates that, in the presence of repulsive Coulombic interactions progressively more and more screened, produce interference effects, due to the hard-body repulsion and attractive forces, but the agreement between observed and calculated SAXS data is satisfactory. The results of the low and moderate NaGDC concentration samples seem to indicate that the aggregation number increase, produced by adding 0.10 M NaCl, is constant within an ionic strength range and occurs by the addition of oligomers formed by trimers. The samples with a variable NaGDC concentration (0.02-0.10 M) at a fixed and high NaCl concentration (0.6 M) contain cylindrical aggregates that give rise to an attractive term effect prevailing on the hard-body repulsive one. The same situation seems to occur in the NaGDC moderate concentration samples.     

The vibrational spectra of the cyanide ligand revisited: the ν(CN) infrared and Raman spectroscopy of Prussian blue and its analogues

A careful analysis of the Raman spectra of the M′_x[M(CN)₆]_y Prussian blue species has enabled a general model for the interpretation of the ν(CN) vibrational spectra. The spectral patterns are derived from those of the metal ions with local O_h symmetry. Two limiting models are discussed. A ‘localized mode’ model, involving matrix‐isolated species, is in much better accord with the observations than a ‘factor group’ model. The use of the infrared feature as fingerprint of specific M CN M′ units arises from the axis‐specific nature of individual T_1u modes. The interpretation of the A_1g and E_g Raman features is done in terms of localized vibrations, with involvement of additional energy terms from the lattice motions. Copyright © 2011 John Wiley & Sons, Ltd.     

Oxidation of steroid α-diketones by thallium (III) acetate : Crystal and molecular structure of a spiro-cyclopentan-a,s-indaceno derivative obtained from 3,4-diketo steroids

Treatment of 2,3-diketo-cholestane (1) with thallium triacetate in acetic acid afforded mainly 3α-carbomethoxy-A-nor-5α-cholestan-2-one (2). Under similar conditions, the 3,4-diketo steroids (3 and 4) underwent extensive rearrangement affording spiro-lactones (9 and 10), in low yields. The structural assignment of the spiro-cholestane derivative was supported by crystallographic X-ray analysis. This product was the result of A and B-ring contractions followed by acid-catalysed cyclization of an unsaturated carboxy intermediate.