Power Conditioning Subsystems for Photovoltaic Central-Station Power Plants: State-of-the-Art and Advanced Technology

Through the combined efforts of governmental agencies and laboratories, private organizations, universities and electric utilities, substantial progress has been made in bringing photovoltaic (PV) systems closer to commercial feasibility. The future availability of central station power conditioner subsystems (CS-PCS) that are efficient, safe, reliable, and economical will play a key role in the acceptance of large-scale PV energy by electric utilities. To accelerate the development of such CS-PCS hardware, the Department of Energy's Photovoltaic Division, as part of its Five Year Plan, has established a goal of a reliable, 98 percent-efficient CS-PCS that in volume production will cost $0.07/Wp. This will help make PV power economically competitive with electric power derived from conventional energy sources. Various governmental agencies and private organizations are cooperating to try to achieve this proposed goal. The combination of a dwindling federal budget for PV research and development (R&D), and the reluctance of American industry to accept the high economic risks involved in its own PV R&D efforts, could shift the leading edge of PV-PCS technology development to foreign competition, in general, and to Japanese industry, in particular.     

Organizational information security policies: a review and research framework

A major stream of research within the field of information systems security examines the use of organizational policies that specify how users of information and technology resources should behave in order to prevent, detect, and respond to security incidents. However, this growing (and at times, conflicting) body of research has made it challenging for researchers and practitioners to comprehend the current state of knowledge on the formation, implementation, and effectiveness of security policies in organizations. Accordingly, the purpose of this paper is to synthesize what we know and what remains to be learned about organizational information security policies, with an eye toward a holistic understanding of this research stream and the identification of promising paths for future study. We review 114 influential security policy-related journal articles and identify five core relationships examined in the literature. Based on these relationships, we outline a research framework that synthesizes the construct linkages within the current literature. Building on our analysis of these results, we identify a series of gaps and draw on additional theoretical perspectives to propose a revised framework that can be used as a basis for future research.     

Nuclear magnetic resonance spectra of two reductively ethylated fuels

A lignite (67.2% C daf) and a coal (89.0% C daf) have been reductively ethylated by Sternberg's procedure⁴ and the spectra, in particular the ¹H and ¹³C n.m.r. spectra, of the products have been obtained. The distribution of hydrogen atoms and, in less detail, of carbon atoms in the reductively ethylated fuels has been determined. It is emphasized that both reductively ethylated fuels contained a variety of structures. The carbon aromaticities of the reductively ethylated lignite and the reductively ethylated coal were 0.41 ± 0.08 and 0.40 ? 0.54 respectively. The aromatic nuclei of the reductively ethylated coal were more highly substituted than those of the reductively ethylated lignite. The ¹H n.m.r. spectra indicate that the reductively ethylated coal and lignite possessed ≈3.5 and ≈2.5 substituents per benzene ring respectively. Resolved absorption in the ¹³C n.m.r. spectra suggests lower figures than these and it was evident that some of the benzene rings in both materials but especially in the reductively ethylated lignite were lightly substituted. The ¹³C n.m.r. spectra show that both materials contained branched and unbranched paraffin chains. Much of the ¹³C n.m.r. spectra however consisted of unresolved absorptions and the ¹³C n.m.r. measurements suggest that the reductively ethylated materials consisted of rigid, relatively immobile molecules of moderate molecular weight. ¹³C n.m.r. absorption by carbon atoms adjacent to aromatic rings was amongst that which was not resolved — though the rings themselves gave resolved absorptions — and this suggests that the aromatic rings were on the periphery of a rigid, perhaps alicyclic, structure.     

The mild oxidation of three Tertiary lignites

Three Tertiary lignites have been oxidized with nitrobenzene and sodium hydroxide at 200 °C in a sealed tube. A scheme of extraction has been used to separate the oxidation products and the resulting solutions have been characterized by their infra-red and ultraviolet absorption spectra and by spot tests. The products contain phenolic hydroxyl and carbonyl — rather than carboxyl — groups. Some of the solutions have been reduced and their n.m.r. spectra recorded. The oxidation procedure shows promise as a method of determining the structure of lignites.     

Chemical and physical characteristics of phosphate rock materials of varying reactivity

Several chemical and physical properties of 10 phosphate rock (PR) materials of varying reactivity were evaluated. These included North Carolina phosphate rock (NCPR), Sechura phosphate rock (SPR), Chatham Rise phosphorite (CRP), Arad phosphate rock (APR), Gafsa phosphate rock (GPR), North Florida phosphate rock (NFPR), Jordanian phosphate rock (JPR), Mexican phosphate rock (MPR), Nauru Island phosphate rock (NIPR), and Makatea Island phosphate rock (MIPR). Concentrations of As and Cd were highest in NCPR and U was higher in APR and CRP than in the other reactive PR materials. Because Cd and U can accumulate in biological systems, it may be necessary to direct more attention towards the likely implications of Cd and U concentrations when evaluating a PR for direct application. Three sequential extractions with 2% citric acid may be more useful for comparing the chemical solubility of PR materials, particularly for those containing appreciable CaCO₃. For each particle-size fraction from <63 to >500 μm, SPR was more soluble in 2% citric acid than was NCPR. The higher solubility of SPR than NCPR in 2% citric acid, 2% formic acid, and neutral ammonium citrate possibly results from a higher chemical reactivity rather than from any difference in the surface area presented for dissolution. The poor relationship obtained between surface area and the solubility of the PR materials in the three chemical extractants suggests that surface area plays a secondary role to chemical reactivity in controlling the solubility of a PR in a chemical extractant. A Promesh plot provided an effective method for describing the particle-size characteristics of those PR materials which occurred as sands. Fundamental characteristics, such as mean particle size and uniformity, can readily be determined from a Promesh plot.     

Therapeutic assessment of SEED: a new engineered antibody platform designed to generate mono- and bispecific antibodies

The strand-exchange engineered domain (SEED) platform was designed to generate asymmetric and bispecific antibody-like molecules, a capability that expands therapeutic applications of natural antibodies. This new protein engineered platform is based on exchanging structurally related sequences of immunoglobulin within the conserved CH3 domains. Alternating sequences from human IgA and IgG in the SEED CH3 domains generate two asymmetric but complementary domains, designated AG and GA. The SEED design allows efficient generation of AG/GA heterodimers, while disfavoring homodimerization of AG and GA SEED CH3 domains. Using a clinically validated antibody (C225), we tested whether Fab derivatives constructed on the SEED platform retain desirable therapeutic antibody features such as in vitro and in vivo stability, favorable pharmacokinetics, ligand binding and effector functions including antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity. In addition, we tested SEED with combinations of binder domains (scFv, VHH, Fab). Mono- and bivalent Fab-SEED fusions retain full binding affinity, have excellent biochemical and biophysical stability, and retain desirable antibody-like characteristics conferred by Fc domains. Furthermore, SEED is compatible with different combinations of Fab, scFv and VHH domains. Our assessment shows that the new SEED platform expands therapeutic applications of natural antibodies by generating heterodimeric Fc-analog proteins.     

Effect of shaking procedures on the neutral ammonium citrate soluble phosphate fraction in fertiliser materials

The effect of four types of shaker, extraction time and temperature on the quantity of phosphate extracted by neutral ammonium citrate was evaluated at two research laboratories. Six unprocessed phosphate rocks, and five partially acidulated and four fully acidulated phosphate fertilisers were investigated. Compared with the more than 10-fold variation in the solubility of the two reactive phosphate rock materials, Sechura and North Carolina, that resulted from using different types of shaker, the solubility of the unreactive phosphate rock materials and the partially and fully acidulated phosphate fertilisers in citrate was influenced to a much smaller degree by the action of the shaker. Sechura was less soluble in citrate that all four unreactive phosphate rock materials when either of the two horizontal shakers were used. This is totally at odds with the documented differences in the chemical reactivity' and agronomic effectiveness of these phosphate rock materials. Not until a wrist-action shaker was used did the solubility of Sechura and North Carolina exceed that of the unreactive materials and approach that obtained with a full end-over-end shake. The neutral ammonium citrate procedure needs to include a more precise definition of the type of shaker and its speed. In laboratories where temperature-controlled extraction is not available, a 24-h shake at 20°C using an orbital or end-over-end apparatus could be an alternative to the standard 1-h extraction at 65°C.