Showing papers by "University of Coimbra published in 1972"
TL;DR: In this article, the relative variance of the pulses from the gas proportional scintillation counter was measured for a full width half maximum of 500 eV for 59 keV and the possibility of using the counter for fast coincidence work is considered.
94 citations
47 citations
TL;DR: In this article, the 2 γ and 4 γ states in 162 Dy, 166 Er, 168 Er and 170 Er have been Coulomb excited with 45-60 MeV 16 O ions.
34 citations
TL;DR: Fragmented sarcolemma isolated from rabbit skeletal muscle bind Ca2+, Mg2+ and Zn2+, which seems to be a non-competitive type of inhibitor.
25 citations
TL;DR: The active Ca2+ bound actively in the presence of ATP by sarcoplasmic reticulum isolated from rabbit skeletal muscle is released by Zn2+ (or Cd2+) as well as by phospholipases A or C and by trypsin, and there is an increase in the passively bound Mg2+.
Abstract: 1
The Ca2+ bound actively in the presence of ATP by sarcoplasmic reticulum isolated from rabbit skeletal muscle is released by Zn2+ (or Cd2+) as well as by phospholipases A or C and by trypsin. Zinc ions also release Mg2+ and are taken up passively by the reticulum membranes, whereas phospholipases A and C and trypsin release only the actively bound Ca2+.
2
Phospholipase A, and to a smaller extent phospholipase C and trypsin, increase the passive cation-binding capacity of reticulum. Thus, concurrently with the loss of selectively bound Ca2+ caused by these agents, there is an increase in the passively bound Mg2+. The increase in the passive cation-binding capacity of reticulum induced by phospholipase depends on the presence of the splitting products of phospholipids, since their removal when digested reticulum is washed with a 2.5% albumin solution decreases the binding capacity to about 50% of the original value.
3
When Ca2+, Mg2+ or Sr2+ is bound passively by reticulum, the ratio of H+ released to either of these divalent cations bound, expressed in terms of nequiv H+ released per nequiv divalent cation bound is about 1.0, but when Zn2+ is taken up, the ratio H+/Zn2+ is only about 0.5, which suggests that some of the Zn2+ is bound at sites that do not release H+ or bind Ca2+.
4
After lipid extraction with 90% acetone, the cation-binding capacity and H+ release are decreased to about 40% of the original values. This effect is particularly evident between pH values of about 6.0 and 8.0. The apparent passive Ca2+-binding affinity is not affected by the lipid removal.
24 citations
TL;DR: La fonction probable of ces structures est finalement discutee, en rapport avec les decouvertes recentes dans le domain of the biochimie et of the cytochimies vegetales.
Abstract: Des phemomenes d'autodigestion cellulaire ont ete decrits tres souvent dans la cellule animale. Generalement ils sont en rapport avec l'activite de structures specialisees, les cytolisomes ou vacuoles autophagiques. Cependant, dans la cellule vegetale les references a l'existence de formations analogues a celles-ci sont plus rares.Au cours de l'etude ultrastructurale des racines de l'Allium cepa et du Lupinus albus, on a trouve, outre les elements normales du vacuome d'autres. types de vacuoles comparables aux vacuoles autophagiques frequemment observes dans la cellule animale, en des conditions normales ou pathologiques. Les vacuoles typiques, apres fixation par le glutaraldehyde-postosmie, se presentent vides ou contenant un precipite dense a structure finement granuleuse fibrillaire.Les autres vacuoles montrent un contenu beaucoup plus dense et heterogene, qui pent se presenter, soit amorphe, soit forme par des granules a l'aspect ribosomale, ou bien organise en structures multilamellaires.Parfois, ces vacuoles renferment des debris cellulaires, ou il est encore possible de reconnaitre quelques organites (mitochondries, corps de Golgi) plus ou moins degenerescents. Alors, elles ressemblent les vacuoles autophagiques ou cytolisomes de la cellule animale. Le reticulum endoplasmique lisse semble jouer un role tres important dans la formation de ces vacuoles autophagiques.La fonction probable de ces structures est finalement discutee, en rapport avec les decouvertes recentes dans le domain de la biochimie et de la cytochimie vegetales.
23 citations
TL;DR: In this article, an expression for the anharmonic collective Hamiltonian containing a variable inertia coefficient is derived, on the basis of the generator coordinate method and the Gaussian overlap approximation.
17 citations
TL;DR: In this article, the authors studied the connectivity, lineconnectivity and J-connection of total graphs and proved some results concerning the connectivity of non-oriented graphs without loops or multiple edges.
Abstract: Our aim is to prove some results concerning the connectivity, lineconnectivity and J-connection or connection modulo J of total graphs. Only finite, nonoriented graphs without loops or multiple edges will be considered. Let G be a graph whose vertex set is V(G) and whose edge set is E(G). The elements of the set V(G)wE(G) will be called the elements of G and two elements of G are said to be associated if they are either adjacent or incident. The total graph T(G) of G is a graph whose vertex set is V(G)uE(G), two vertices being joined by an edge if and only if they are associated elements of G (see [1]). As an example of a graph G and its total graph T(G) see Fig. 1. We make an obvious distinction: small rings represent point-vertices of T(G) (x is a point-vertex x ~ E(G)). T(G) contains both G and its line-graph or interchange graph [4] L(G) as disjoint subgraphs. Remember that by definition, V[L(G)] =E(G) and two vertices of L(G) are linked by an edge if and only if the corresponding edges of G are adjacent. Edges of T(G) belonging neither to G nor L(G) form what will be called the incidence-graph I(G) of G. By definition the connectivity k(G) of G is the least number of vertices whose removal disconnects G or reduces G to a single vertex; a set of k(G) vertices satisfying this condition is called a minimal separating vertex set of G. Moreover G is n-connected if and only if k(G) >= n. On the
6 citations
TL;DR: The cycle multiplicity π2′(G) of a graph G, defined by Chartrand, Geller, and Hedetniemi as mentioned in this paper, is the maximum number of line-disjoint cycles contained in G. If G has cycles, then the right members of the preceding equalities added to π 2′(Ge) give lower bounds for the left members.
4 citations
TL;DR: In this article, a simple procedure for converting the integral eigenvalue equation of the generator coordinate method into a differential eigen value equation is presented, assuming the validity of the Gaussian overlap approximation.
3 citations
TL;DR: In this paper, the authors propose a justification for the well-known VMI models of Diamond et al. and Mariscotti et al based upon the method of generator coordinates, and conclude that, contrary to the general trend, the stretching model is to be preferred over the region of good vibrators.
TL;DR: In this article, the authors proposed a method for studying the collective vibrations of an excited intrinsic state, which is based on the generator-coordinate theory, and the new aspect introduced is the description of the intrinsic excited state as a Tamm-Dancoff solution.
TL;DR: In this paper, the authors reported losses at 4.2 K in a cylinder of magnetic reversible niobium subjected to a sinusoidal magnetic field within a frequency range of 20−260 c s −1 and waveforms related to the penetration of magnetic flux.
TL;DR: In this article, the real and imaginary parts of the magnetic permeability at small, low-frequency magnetic fields were measured by measuring cylinders of pure niobium, and they were led to the conclusion that pinning sites at the surface are needed for the existence of surface superconductivity.
Abstract: Surface superconductivity has been investigated by measuring the real and imaginary parts of the magnetic permeability at small, low-frequency magnetic fields. The samples used were cylinders of Ta
92
Nb
8
, Ta
95
Nb
5
, and pure niobium which have suffered different bulk and surface treatments. By our measurements we are led to the conclusion that pinning sites at the surface are needed for the existence of surface superconductivity.