A warm layer in Venus' cryosphere and high-altitude measurements of HF, HCl, H2O and HDO

Venus has thick clouds of H2SO4 aerosol particles extending from altitudes of 40 to 60 km. The 60-100 km region (the mesosphere) is a transition region between the 4 day retrograde superrotation at the top of the thick clouds and the solar-antisolar circulation in the thermosphere (above 100 km), which has upwelling over the subsolar point and transport to the nightside. The mesosphere has a light haze of variable optical thickness, with CO, SO2, HCl, HF, H2O and HDO as the most important minor gaseous constituents, but the vertical distribution of the haze and molecules is poorly known because previous descent probes began their measurements at or below 60 km. Here we report the detection of an extensive layer of warm air at altitudes 90-120 km on the night side that we interpret as the result of adiabatic heating during air subsidence. Such a strong temperature inversion was not expected, because the night side of Venus was otherwise so cold that it was named the 'cryosphere' above 100 km. We also measured the mesospheric distributions of HF, HCl, H2O and HDO. HCl is less abundant than reported 40 years ago. HDO/H2O is enhanced by a factor of approximately 2.5 with respect to the lower atmosphere, and there is a general depletion of H2O around 80-90 km for which we have no explanation.     

De l'emploi d'isotopes radioactifs artificiels,dans le but d'exercer un effet radio-biologique localisé

Summary One of the authors has previously reported on a method which consists in the utilization of an artifical radioactive isotope (Zn⁶³), suspended in a suitably prepared solution ofpectin, for the production oflocalized biological radiation effects.This « macromolecular occlusion » of the radioactive isotope enables one to perform intraperitoneal injections (in cases of cancer of the ovaries with severe metastatic peritoneal extension), evidently also instillations in cavernous organs, and furthermore direct intratumoral injections, without diffusion of the radioactivity outside the treated areas, as shown both by autoradiographs and controls of blood and urine specimens with a Geiger counter.The authors investigated further whether this procedure would also be suitable for obtaining, by means ofintravenous injections, alocalized radiation effect within thelungs, as presumably the radiozinc, held in the large molecules of pectin, could thus be retained in the pulmonary capillaries. Intravenous injections of such a pectin solution containing radiozinc were performed on rabbits, and autoradiographic controls gave evidence of this expected fixation within the lungs.For the purpose of preliminary clinical investigation 40 millicuries of Zn⁶³ suspended in 6 cm³ of a 3 p. c. isotonic pectin solution were injectedintravenously in a female patient with mainly pulmonary metastases of a previously operated hypernephroma. This patient had been also submitted to X-ray therapy. In spite of a poor general condition, the injection was well tolerated. Autoradiographic controls showed quite clearly that the radioactivity remains precisely localized within the pulmonary areas. No radioactivity whatsoever was demonstrated with the counter in the urine eliminated by this patient after the injection, a fact which points to a rather amazing accuracy of the fixation of the radiozinc in the lungs. This first clinical experience seems quite interesting in view of improving the therapeutic possibilities of pathological, especially neoplastic pulmonary conditions.     

The Equivalence Myth of Quntum Mechanics (Addendum)

This addendum non-trivially strengthens one of the six claims of my two-part paper ‘The Equivalence Myth of Quantum Mechanics’, published in this journal in 1997.     

H+ passivation of poly-si solar cells processed by different annealing processes

The effects of different annealing processes on the photovoltaic (PV) properties and the spectral response as well as minority carrier lifetime in the bulk of unanalyzed PF₅ ion implantation poly-Si solar cells were investigated. The different hydrogen passivation effects of defects in poly-Si induced by three heat treatment processes are reported. We used RTA-rapid thermal annealing, YAG pulse laser annealing and CTSA-classical three-step annealing for this study. The results show that cells processed by RTA (800°C, 4 sec) achieved the best PV properties and spectral response among all annealed samples. Under this precess condition, no or few defects were induced in bulk. While RTA (>-850°C for 4 sec), CTSA as well as YAG laser processes induced defects of different nature and concentration in the bulk of cells. It is further shown that hydrogen ion implantation significantly improved, the performances of poly-Si cells. It is able to efficiently remove the YAG laser induced defects in bulk. However, it cannot completely passivate the defects induced by CTSA and RTA processes. Biography: LI Jin-chai (1946-), male, Associate professor. Research direction: studies of ion beam modification of materials and films of new functionail materials.     

In vivo competition between self peptides and foreign antigens in T-cell activation

Cytotoxic and helper T lymphocytes recognize foreign antigen in the form of short peptides associated with class I and class II major histocompatibility complex (MHC) molecules, respectively. A recent study of the three-dimensional structure of a class I MHC molecule revealed a cleft formed by the amino-terminal half of the protein, which could serve as the binding site for these peptides. Because an individual possesses only a limited set of different MHC molecules, each molecule of this set must have the ability to bind a large number of different peptides in order to ensure full immunocompetence. Thus, it can be anticipated that peptides with unrelated sequences compete for binding to the same MHC molecule, and, indeed, this has been shown to occur in vitro. We therefore decided to see whether such competition could also regulate the cell responses in vivo. We have found that a synthetic peptide corresponding to residues 46-62 of mouse lysozyme, although not immunogenic itself, effectively inhibits the priming for T-cell responses when injected into mice together with foreign protein or peptide antigens. The inhibition observed strictly correlates with the capacity of the competitor to bind to the particular MHC molecule presenting the foreign antigen, and its extent depends on the molar ratio between antigen and competitor.     

Atomic-scale imaging of nanoengineered oxygen vacancy profiles in SrTiO3

At the heart of modern oxide chemistry lies the recognition that beneficial (as well as deleterious) materials properties can be obtained by deliberate deviations of oxygen atom occupancy from the ideal stoichiometry. Conversely, the capability to control and confine oxygen vacancies will be important to realize the full potential of perovskite ferroelectric materials, varistors and field-effect devices. In transition metal oxides, oxygen vacancies are generally electron donors, and in strontium titanate (SrTiO3) thin films, oxygen vacancies (unlike impurity dopants) are particularly important because they tend to retain high carrier mobilities, even at high carrier densities. Here we report the successful fabrication, using a pulsed laser deposition technique, of SrTiO3 superlattice films with oxygen doping profiles that exhibit subnanometre abruptness. We profile the vacancy concentrations on an atomic scale using annular-dark-field electron microscopy and core-level spectroscopy, and demonstrate absolute detection sensitivities of one to four oxygen vacancies. Our findings open a pathway to the microscopic study of individual vacancies and their clustering, not only in oxides, but in crystalline materials more generally.     

Passenger deletions generate therapeutic vulnerabilities in cancer

Inactivation of tumour-suppressor genes by homozygous deletion is a prototypic event in the cancer genome, yet such deletions often encompass neighbouring genes. We propose that homozygous deletions in such passenger genes can expose cancer-specific therapeutic vulnerabilities when the collaterally deleted gene is a member of a functionally redundant family of genes carrying out an essential function. The glycolytic gene enolase 1 (ENO1) in the 1p36 locus is deleted in glioblastoma (GBM), which is tolerated by the expression of ENO2. Here we show that short-hairpin-RNA-mediated silencing of ENO2 selectively inhibits growth, survival and the tumorigenic potential of ENO1-deleted GBM cells, and that the enolase inhibitor phosphonoacetohydroxamate is selectively toxic to ENO1-deleted GBM cells relative to ENO1-intact GBM cells or normal astrocytes. The principle of collateral vulnerability should be applicable to other passenger-deleted genes encoding functionally redundant essential activities and provide an effective treatment strategy for cancers containing such genomic events.