Similarity‐Based Virtual Screening with a Bayesian Inference Network

An inference network model for molecular similarity searching: The similarity search problem is modeled using inference or evidential reasoning under uncertainty. The inference network model treats similarity searching as an evidential reasoning process in which multiple sources of evidence about compounds and reference structures are combined to estimate resemblance probabilities.

     

Operating procedure automation to enhance safety of nuclear power plants

Use of logic statements and computer assist are explored as means for automation and improvement on design of operating procedures including those employed in abnormal and emergency situations. Operating procedures for downpower and loss of forced circulation are used for demonstration. Human-factors analysis is performed on generic emergency operating procedures for three strategies of control; manual, semi-automatic and automatic, using standard emergency operating procedures. Such preliminary analysis shows that automation of procedures is feasible provided that fault-tolerant software and hardware become available for design of the controllers. Recommendations are provided for tests to substantiate the promise of enhancement of plant safety. Adequate design of operating procedures through automation may alleviate several major operational problems of nuclear power plants. Also, automation of procedures is necessary for partial or overall automatic control of plants. Fully automatic operations are needed for space applications while supervised automation of land-based and offshore plants may become the thrust of new generation of nuclear power plants.     

An assessment of the market potential for small solar powered desalination plants

The introduction of a new technological system to the commercial market is helped by following established procedures for estimating the potential market for the product. This paper describes the results of a preliminary market analysis for the manufacture and sale of small solar powered desalination (SSPD) systems in Middle Eastern Countries. Overall results indicate that manufacture and sales of the SSPD system are promising from both technical and economical standpoints. However, until prototypes are built, some caution is indicated for financing of production and for purchasing of equipment. Prototype systems are being developed to demonstrate in actuality the commercial acceptance and economic viability of the system.     

Cast and aged β-NiAl-β′-Ni2AlTi-γ′-Ni3Al-α-Cr alloys: a microstructural and mechanical properties investigation

Microstructural development and stability in cast Ni-30 at% Al-21 at% Cr-4 at% Ti, Ni-28 at% Al-18 at% Cr-6 at% Ti and Ni-26 at% Al-19 at% Cr-8 at% Ti alloys are examined in this paper. The paper considers the extent to which microstructural control and stability is improved in these alloys, when compared with earlier work by the authors on similar materials with lower aluminum (25 or 26 at%) and higher titanium (11 to 15 at%) contents. The paper discusses detailed transmission electron microscopy investigations of both as-cast and aged (140 h at 850 and 1100°C) samples. Attention is focussed on the transformation of L2₁ type (nominally Ni₂AlTi) dendrites. In particular, the influence of the formation of intradendritic L1₂ type (nominally Ni₃(Al,Ti)) on the stability of the -phase is examined. Morphological changes and phase transformations within a --Cr eutectic are discussed. Various modes of second-phase precipitation are considered. The microstructures of selected samples are correlated with mechanical properties determined by tensile testing and fractography.     

Efficient generation of the ideals of a poset in Gray code order

Preusse and Ruskey [G. Pruesse, F. Ruskey, Gray codes from antimatroids, Order 10 (1993) 239-252] presented an algorithm for generating a Gray code for the ideals of a poset, where two adjacent ideals differ by one or two elements. Their algorithm takes O(n) amortized time per ideal. Squire [M. Squire, Enumerating the ideals of a poset, http://citeseer.ist.psu.edu/465417.html] presented a recurrence for the ideals of a poset that enabled him to find an algorithm for generating these ideals in O(logn) amortized time per ideal, but not in Gray code order. We use Squire's recurrence to find a Gray code for the ideals of a poset, where two adjacent ideals differ by one or two elements. In the worst case our algorithm has the same complexity as that of Pruesse and Ruskey and in the other cases its complexity is better and approaches that of Squire's algorithm.     

Organophosphorus compounds. XXI. The Reaction of Alkyl Phosphites with 10-Methyleneanthrone and 10-Arylideneanthrones

The reaction of triethyl and trimethyl phosphites with 10-methyleneanthrone 1a , 10-benzylideneanthrone 1b , 10-(p-chlorobenzylidene)anthrone 1c , 10-(p-methoxybenzylidene)anthrone 1d and 10-(diphenylmethylene)anthrone 1e , has been investigated. Depending on the experimental conditions, reaction of 1a with triethyl phosphite gives diethyl (10-ethoxy-9-anthryl)methylphosphonate 3a and/or the spiroanthrone 8a , whereas, with trimethyl phosphite, dimethyl [(9, 10-dihydro-10-oxo-9-anthryl)methyl]phosphonate 11a is formed. Compound 1b on reaction with trimethyl phosphite yields dimethyl [α-(9,10-dihydro-10-oxo-9-anthryl) benzyl]phosphonate 11b . Reaction of 1c with triethyl phosphite and trimethyl phosphite gives rise to diethyl [p-chloro-α-(10-ethoxy-9-anthryl)benzyl]phosphonate 3c and dimethyl [p-chloro-α-(9,10-dihydro-10-oxo-9-anthryl)benzyl]phosphonate 11c respectively. Compounds 1d and 1e did not react with alkyl phosphites. Possible reaction mechanisms are considered and the structural assignments are based on analytical and spectroscopic results.     

Contributions of chemical and mechanical surface properties and temperature effect on the adhesion at the nanoscale

The atomic force microscope (AFM) is a powerful tool to investigate surface properties of model systems at the nanoscale. However, to get semi-quantitative and reproducible data with the AFM, it is necessary to establish a rigorous experimental procedure. In particular, a systematic calibration procedure of AFM measurements is necessary before producing reliable semi-quantitative data. In this paper, we study the contributions of the chemical and mechanical surface properties or the temperature influence on the adhesion energy at a local scale. To reach this objective, two types of model systems were considered. The first one is composed of rigid substrates (silicon wafers or AFM tips covered with gold) which were chemically modified by molecular self-assembling monolayers to display different surface properties (methyl and hydroxyl functional groups). The second one consists of model polymer networks (cross-linked polydimethylsiloxane) of variable mechanical properties. The comparison of the force curves obtained from the two model systems shows that the viscoelastic contributions dominate for the adhesion with polymer substrates, whereas, chemical contributions dominate for the rigid substrates. The temperature effect on the adhesion energy is also reported. Finally, we propose a relation for the adhesion energy at the nanoscale. This relation relates the energy measured during the separation of the contact to the three parameters: the surface properties of the polymer, the energy dissipated within the contact zone and the temperature.