X-ray photoemission and the electronic structure of solids

The principles of X-ray photoelectron spectroscopy are outlined. The application of this technique to the study of the electronic structure of metals, alloys and compounds is illustrated using data in Ag, β-brass, ReO₃ and VO₂. In the latter a major change in the density of states is observed on passing through the metal-insulator transition.     

The diffusion of moisture in sorbent solids part II. activated alumina

Ordinary and thermal diffusion of moisture in activated alumina are investigated using a new diffusion cell design and scheme of analysis reported earlier. The specific form of the mass flux equation has a pronounced effect on the magnitude of the associated thermal diffusion ratio. In the case of activated alumina-moist air, if a partial pressure gradient is used, then the thermal diffusion term is small if not zero.Free, Knudsen and surface diffusion all play a part in the diffusion through activated alumina. However, surface diffusion makes the major contribution and for this reason the model in this case can be simplified to a two parameter surface model.The activation energy for surface diffusion is constant and is approximately equal to the mean isosteric heat of absorption. In addition, mean pore radius, turtuosity, and other physical constants are computed from the least square fit of experimental data. Furthermore, the model is theoretically consistent over the entire concentration range (0≦ C_A ≦ C_Asat).A new fact about activated alumina (Grade F1) it that it does not transfer moisture in a nonisothermal condition so long as the partial pressures of moisture on the two sides of the pellet are the same. There appears to be no previous report of this fact in the periodical literature.     

The structure of invention

This paper explores the process by which radically novel technologies - ones such as radar, the turbojet, or the polymerase chain reaction - come into being. It shows that this process - “invention” - has a certain logical structure common to all cases. Invention is a process of linking some purpose or need with an effect that can be exploited to satisfy it. It may begin with a purpose or need for which existing methods are not satisfactory; this forces the seeking of a new principle (the idea of an effect in action). Or it may begin with a phenomenon or effect itself - usually a freshly discovered one - for which some associated principle of use suggests itself. Either way, translating this base principle into physical reality requires the creation of suitable working parts and supporting technologies. These raise their own challenges or problems, the solution of which may raise further challenges. As a result, invention is a recursive process: it repeats until each challenge or problem (and subproblem, and sub-subproblem) resolves itself into one that can be physically dealt with. It is challenging, usually lengthy, part-conceptual, and part-experimental.     

国外产业结构转型理论述评

产业结构与经济增长具有密切的双向因果关系。文章从需求和供给两个角度以及最新的进展方面对产业结构转型这一领域的研究进行了梳理。其中,需求角度的产业结构转型主要是收入增长和多样化、专业化的需求导致的;供给角度的产业转型则基于农业和工业生产率的提高。政策、制度以及人力资本的积累会影响到产业转型。该理论的最新进展是围绕着同时考虑供给和需求面对产业转型的影响以及考虑符合卡尔多Kaldor事实的产业结构转型两个方面展开的。