Search results for "Homogeneous"

Homogeneous Metal-Based Catalysis in Supercritical Carbon Dioxide as Reaction Medium

2016

Above 31.1 degrees C and 73.8 bar, carbon dioxide reaches the supercritical state, being transformed into a fluid (scCO(2)) that has attracted interest in the last few decades as reaction medium for several transition-metal-catalyzed organic transformations. The main feature of this fluid rests on its capability to dissolve large amounts of other gases such as hydrogen, carbon monoxide, ethylene, or even methane and light alkanes. In this manner, very high concentrations of these reactants are available for catalysis. In this contribution a review of the main achievements of the use of transition-metal complexes as catalysts in scCO(2) is presented.

Cost uncertainty and trade liberalization in international oligopoly

1998

Abstract Trade liberalization has been shown to be unfavourable for firms of at least one country for the homogeneous goods case in an environment of certainty. We show that, in the presence of private cost information and for ex ante identical firms, oligopolistic firms will prefer to operate under free trade rather than under autarky in homogeneous goods industries provided there exists a certain degree of firms' heterogeneity and a sufficiently large amount of uncertainty. For the particular case of symmetry both in demand and industry sizes, the firms of at least one country prefer to operate under autarky rather than under free trade.

MIXED OLIGOPOLY WITH HOMOGENEOUS GOODS

1993

Peritoneal invasion and metachronous peritoneal metastases after colon cancer surgery: The role of homogeneous, reliable assessment and confounders

2021

Preoperative Radiochemotherapy and Radical Surgery of Advanced Head and Neck Cancers — Results of a Prospective, Multicenter DÖSAK Study

1994

Present research concerning the efficiacy of therapeutic strategies for squamous cell carcinomas of the oral cavity and the oropharynx profits from former observational studies. The so-called retrospective German, Austrian, and Swiss Association for Head and Neck Tumors (DOSAK) study (Platz et al. 1986) served to review existing proposals for classification (UICC 1973, 1978; AJC 1978) and to develop a statistical classification which enables the head and neck oncologist to define prognostically homogeneous patient collectives. The treatment-dependent prognostic index (TPI) was the corresponding result (Platz et al. 1982).

Efectos de la crisis en el crédito comercial concedido y relevancia de la diversificación de la actividad

2014

ResumenEl objetivo de este trabajo es estudiar las razones por las que las empresas manufactureras españolas conceden crédito comercial a sus clientes. Hemos analizado teórica y empíricamente 2 aspectos: el efecto producido por la crisis financiero-económica y la importancia que tiene la diversificación de la actividad y el tipo de cliente al que se le concede el crédito comercial. Las principales conclusiones que obtenemos son, por una parte, que el incremento del crédito comercial concedido en periodo de crisis provoca que las empresas sean menos competitivas, y en segundo lugar aportamos evidencia de que la diversificación de la actividad y el hecho de que los clientes sean más o menos h…

Correlation coefficients in human skulls: Significant sexual differences

1987

This study of 500 male and female skulls proves: significant differences of correlation coefficients (p less than or equal to 0.01) occur between the two sexes. The combined variables are: 1. bizygomatic breadth (45)/skull base length (5) 2. bizygomatic breadth (45)/foramen magnum length (7) 3. bizygomatic breadth (45)/foramen magnum breadth (16) 4. bizygomatic breadth (45)/basion-bregma height (17) 5. foramen magnum breadth (16)/skull base length (5) Female skulls have generally higher correlation coefficients values than males which is interpreted as an indication of homogeneous growth.

Mechanistic aspects of oxalic acid oxidation by photocatalysis and ozonation

2008

Oxalic acid has been oxidised in acidic aqueous solutions (pH 3) using photocatalysis and ozonation alone or coupled. The simultaneous presence of ozone, titanium dioxide and near UV irradiation increases the oxidation rate of oxalic acid to values greater than those deriving from the single contributions of photocatalysis and ozonation. In particular in the present paper ozonation alone, heterogeneous photocatalysis and also combined ozonation with heterogeneous photocatalysis have been used for the oxidation of oxalic acid at acidic pH in the presence of TiO2 Degussa P25. A likely mechanism, able to explain both the homogeneous and heterogeneous processes, is discussed.

Incomplete retention of radiation damage in zircon from Sri Lanka

2004

A suite of 18 zircon gemstones from placers in the Highland/Southwestern Complex, Sri Lanka, were subjected to a comprehensive study of their radiation damages and ages. The investigation included X-ray diffraction, Raman and PL spectroscopy, electron microprobe, PIXE and HRTEM analysis, as well as (U-Th)/He and SHRIMP U-Th-Pb age determinations. Zircon samples described in this study are virtually homogeneous. They cover the range from slightly metamict to nearly amorphous. Generally concordant U-Th-Pb ages averaging 555 ± 11 Ma were obtained. Late Ordovician zircon (U-Th)/He ages scattering around 443 ± 9 Ma correspond reasonably well with previously determined biotite Rb-Sr ages for rock…

Solutions of elliptic equations with a level surface parallel to the boundary: stability of the radial configuration

2016

A positive solution of a homogeneous Dirichlet boundary value problem or initial-value problems for certain elliptic or parabolic equations must be radially symmetric and monotone in the radial direction if just one of its level surfaces is parallel to the boundary of the domain. Here, for the elliptic case, we prove the stability counterpart of that result. We show that if the solution is almost constant on a surface at a fixed distance from the boundary, then the domain is almost radially symmetric, in the sense that is contained in and contains two concentric balls $${B_{{r_e}}}$$ and $${B_{{r_i}}}$$ , with the difference r e -r i (linearly) controlled by a suitable norm of the deviation…