Densities and phase equilibria of hydrogen, propane and vegetable oil mixtures. Experimental data and thermodynamic modeling

Heterogeneous catalytic gas-liquid reactions are intensified when carried out in the homogenous fluid phase by means of a supercritical co-solvent. For instance, supercritical propane is used to enhance yield in the hydrogenation of vegetable oils. Besides phase equilibrium knowledge, volumetric information is also needed to elucidate kinetic mechanisms and design continuous supercritical reactors. In this work, we report new experimental PvT data of the reactive mixture H2+sunflower oil+propane using the isochoric method. In addition, the phase equilibria and PvT data are modeled with the GCA and RK-PR equations of state, respectively. The isochoric method not only provides PvT information under the reaction conditions, but also the reactive system compressibility, key variable to attain enhanced transport properties in the supercritical reactors.Fil: Hegel, Pablo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Cotabarren, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Brignole, Esteban Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Pereda, Selva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. University of KwaZulu-Natal; Sudáfric

Primary radiotherapy in progressive optic nerve sheath meningiomas: a long-term follow-up study

Background/aims: To report the outcome of primary radiotherapy in patients with progressive optic nerve sheath meningioma (ONSM). Methods: The clinical records of all patients were reviewed in a retrospective, observational, multicentre study. Results: Thirty-four consecutive patients were included. Twenty-six women and eight men received conventional or stereotactic fractionated radiotherapy, and were followed for a median 58 (range 51–156) months. Fourteen eyes (41%) showed improved visual acuity of at least two lines on the Snellen chart. In 17 (50%) eyes, the vision stabilised, while deterioration was noted in three eyes (9%). The visual outcome was not associated with age at the time of radiotherapy (p=0.83), sex (p=0.43), visual acuity at the time of presentation (p=0.22) or type of radiotherapy (p=0.35). Optic disc swelling was associated with improved visual acuity (p<0.01) and 4/11 patients with optic atrophy also showed improvement. Long-term complications were dry eyes in five patients, cataracts in three, and mild radiation retinopathy in four. Conclusion: Primary radiotherapy for patients with ONSM is associated with long-term improvement of visual acuity and few adverse effects.Peerooz Saeed, Leo Blank, Dinesh Selva, John G. Wolbers, Peter J.C.M. Nowak, Ronald B. Geskus, Ezekiel Weis, Maarten P. Mourits, Jack Rootma

L'Expressió al testicle de la proteïna transportadora d'esteroides sexuals humana (SHBG) té lloc a les cèl·lules germinals i no a les cèl·lules de Sertoli

El gen de la proteïna transportadora d'esteroides sexuals humana (hSHBG) conté dues unitats de transcripció diferents. Una d'aquestes unitats de transcripció fa aproximadament 4,3 kb, i codifica un precursor polipeptídic que és processat i secretat pels hepatòcits, i que donarà lloc a la SHBG plasmàtica. La seqüència promotora humana d'aquesta unitat de transcripció és diferent de la seqüència dels promotors dels altres mamífers que expressen el gen de la SHBG a les cèll. ules de Sertoli. Concretament, el promotor humà de la SHBG conté un lloc d'unió per a uns factors de transcripció anomenats USF, que s'uneixen al promotor i inhibeixen la seva expressió a les cèll. ules de Sertoli. Tot i que el gen de la SHBG humana no s'expressa a les cèll. ules de Sertoli, es poden detectar transcrits per a la SHBG al testicle humà. Aquests transcrits contenen un exó 1 alternatiu, es troben a les cèll. ules germinals i són producte d'una altra unitat de transcripció que conté una regió promotora que es troba a unes 2 kb de la primera regió promotora. Els transcrits d'aquesta segona regió promotora codifiquen una isoforma de la SHBG que és uns 5 kDa més petita que la SHBG plasmàtica. Aquesta isoforma de la SHBG s'acumula als espermatozoides entre la membrana exterior de l'acrosoma i la membrana plasmàtica, i s'allibera al medi durant la reacció de capacitació. Aquestes diferències tan importants en l'expressió del gen de la SHBG al testicle entre l'humà i els altres mamífers ens obliguen a reconsiderar la funció de la SHBG en el testicle en relació a la reproducció masculina.The human sex hormone binding globulin (SHBG) gene contains at least two transcription units. A 4.3 kb human SHBG transcription unit encodes the precursor polypeptide, which is processed and secreted by hepatocytes as plasma SHBG. The proximal promoter of this transcription unit differs from the corresponding sequence in other mammals, in which it is also expressed in Sertoli cells. In particular, its proximal promoter sequence contains a binding-site for USF transcription factors that represses its activity in Sertoli cells. Although human SHBG is not expressed in Sertoli cells, human SHBG transcripts containing an alternative exon 1 sequence are present in testicular germ cells. These are the products of an ~8 kb human SHBG transcription unit, and they appear to encode an SHBG isoform that is 4-5 kDa smaller than plasma SHBG. This sperm SHBG isoform accumulates between the outer acrosomal membrane and the sperm plasma membrane, and it is released during the capacitation reaction. These remarkable differences in the expression of human SHBG in the testis, when compared to other mammals, force us to reconsider the functional significance of SHBG expression in the testis in relation to male reproduction

Ground state of a partially melted Wigner molecule

We consider three spinless fermions free to move on 2d square lattice with periodic boundary conditions and interacting via a U/r Coulomb repulsion. When the Coulomb energy to kinetic energy ratio r_s is large, a rigid Wigner molecule is formed. As r_s decreases, we show that melting proceeds via an intermediate regime where a floppy two particle molecule coexists with a partially delocalized particle. A simple ansatz is given to describe the ground state of this mesoscopic solid-liquid regime.Comment: to appear in Europhysics Letter

Bargmann-Michel-Telegdi equation and one-particle relativistic approach

A reexamination of the semiclassical approach of the relativistic electron indicates a possible variation of its helicity for electric and magnetic static fields applied along its global motion due to zitterbewegung effects, proportional to the anomalous part of the magnetic moment.Comment: 10 pages, LATEX2E, uses amsb

Role of a parallel magnetic field in two dimensional disordered clusters containing a few correlated electrons

An ensemble of 2d disordered clusters with a few electrons is studied as a function of the Coulomb energy to kinetic energy ratio r_s. Between the Fermi system (small r_s) and the Wigner molecule (large r_s), an interaction induced delocalization of the ground state takes place which is suppressed when the spins are aligned by a parallel magnetic field. Our results confirm the existence of an intermediate regime where the Wigner antiferromagnetism defavors the Stoner ferromagnetism and where the enhancement of the Lande g factor observed in dilute electron systems is reproduced.Comment: 4 pages, 3 figure