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Notes: Replicas of unerupted and erupted human enamel submitted to protein-disrupting solutions showed: (1) an inequal distribution of porosities in the subsurface; (2) such porosities were restricted gradually in each enamel subunit (enamel segments limited by two perikymata). First the whole surface was covered by a network, reduced at a later stage to half of the surface and ultimately the porosities were present only in the perikymata. This paper confirms the occurrence of a late maturation at stage where cells are no longer active and details the time-dependent involution of these porosities.

Notes: The dissolution and dissolution rate of dental luting cements was measured longitudinally. Cement samples in enamel were placed in a full prosthesis and worn in the mouth for up to 6 months. At given intervals, replicas of the cement surfaces were made and quantified by means of SEM stereographic photographs. With a stereometer the distance between cement surface and original enamel surface can be determined quantitatively. The results show in vivo solubility rates for zinc-phosphate and glass-ionomer cement of about 80μ week−1 and 2μm week−1 respectively.

Notes: A method is described to quantify marginal leakage of amalgam restorations in vitro as a function of time. The method consists of the determination of the amount of nitrogen gas passing through the margins of the restoration at 2atm. pressure in 30min.The method described needs about sixteen specimen per experiment. The standard error is 20-30% of the mean leakage value and is independent of the type of condensation and the amalgam type.Two amalgams, the non-γ2-Dispersalloy and the conventional, Amalcap was compared longitudinally over a period of 4 months. The results showed:〈list xml:id="l1" style="custom"〉1The marginal leakage of Dispersalloy decreased strongly with time; the time dependency of Amalcap was less pronounced.2That carefully condensed Amalcap showed significantly less marginal leakage than Dispersalloy.3Whereas the marginal leakage of Amalcap was dependant on the condensation procedure, the leakage of Dispersalloy did not depend strongly on it.

Notes: The surface free energy γs of human dentin treated with sodium fluoride, acidulated phosphate fluoride, and aminfluoride solutions has been determined by means of contact angle measurements. Application of an aminfluoride solution slightly increased the total surface free energy from 75 to 80 erg. cm−2. The γs values of dentin after a neutral sodium fluoride application decreased to 62 erg. cm−2. APF solutions hardly influenced the surface free energy γs. This study showed that fluoride applications change the surface free energy of human dentin.Extrapolation of the results of this study and the in vitro results on cell spreading indicated that aminfluoride applications might be favorable for the reattachment of periodontal tissues.

Notes: Abstract The photoproduction of charged pions on12C has been investigated using the tagged photon beam facility at the Bonn 500 MeV synchrotron. Pions were detected in a broad range magnetic spectrometer. Double differential cross sections for pion emission at fixed photon energies are presented. The integration of the measured distributions yields the total cross section for inclusive pion production. The data are compared to the predictions of a simple model that takes the quasifree production of pions and their subsequent scattering and reabsorption into account.

Notes: Abstract Data are presented for proton emission off12C using tagged photons in the energy range 200–385 MeV. The protons are detected in a magnetic spectrometer. In addition, charged or neutral particles can be measured with a scintillation counter setup. Contributions to the proton energy spectra from primary pion production and quasideuteron reactions are separated using the coincidence data. The total12C(γ, p)X cross section is derived as a function of the photon energy. The data are compared to the predictions of an intranuclear cascade calculation. Final state interactions have to be taken into account to describe the data.

Notes: Abstract The photoproduction of neutral pions on12C has been investigated between threshold and 450 MeV photon energy using the tagged photon beam at the Bonn 500 MeV synchrotron and a large acceptance detector. Theπ 0 detector consists of cylindrical wire chambers covering a solid angle of nearly 4π. Using a scintillation counter as an active12C target an attempt was made to separate coherent and incoherentπ 0 photoproduction. The measured total and differential cross sections are compared to corresponding theoretical calculations.

Notes: Abstract The three subtribes which are recognized within the tribe Vandeae are represented in the tropical African and Malagasy regions. All taxa of the Vandeae have a monopodial growth habit. The first subtribe, Sarcanthinae, is mainly Asian-Australasian, but a few of its species occur in Madagascar and in Africa. The other two subtribes. Angraecinae and Aerangidinae, are both represented in the latter two regions. The Angraccinae is characterized by the presence of a short rostellum, but this is elongated in the Aerangidinae. According to earlier authors there is a correlation between presence of the short rostellum and a basic chromosome number of x=19 in the Angraecinae, and between the presence of an elongated rostellum and a basic number of x=25 in the Aerangidinae. The results presented in this paper are placed in perspective with the chromosome numbers recorded by other authors. From the resulting chromosome number survey it appears that only part of the Angraecinae (Aeranthes, several species of Angraecum, Cryptopus and Jumellea) have a basic number of x=19; some members of the Angraecinae (other species of Angraecum) were found to have a basic number of x=21, 24 and 25. The Aerangidinae is not characterized by a single basic number of x=25 but by a series ranging from x=23 to x=27, of which x=23, 24 and 25 are the most frequent. The genus Calyptrochilum, although having a distinetly elongated rostellum, is characterized by a basic number of x=19 and its position within the Aerangidinae may therefore be questioned. The present evidence suggests that too much weight has been attributed to a single character, i.e. the shape of the rostellum, in distinguishing the two subtribes. As there appear to be two groups according to basic number in Angraecum, it appears questionable whether Angraecum, as presently conceived, is a ‘natural’ genus. Further chromosomal and other taxonomic evidence is needed to substantiate the challenge to the present views in respect of Angraecum. Taxa with x=19 appear to be frequent in Madagascar and the other islands in the Indian Ocean, whereas taxa with x=21 to 27 mainly occur on the African continent. The predominance of x=19 in the Malagasy flora suggests a link with the monopodial taxa of the Asian and Australasian floras, which are exclusively based on x=19.