Application of holographic interferometry to the vibrational analysis of the harpsichord

This paper presents an original piece of research using holographic interferometry as a quantitative optical diagnostic. The object under investigation was the soundboard of a harpsichord. The results obtained show that it is possible to measure the spatial vibrational behaviour of the whole soundboard with an accuracy of better than 170 nm. Several features which characterize the vibration behaviour of the soundboard have been visualized including a discontinuity created by a crack which has resulted in a phase change of the interferometric fringes. Finally, the theoretical model response of the harpsichord soundboard is determined and compared to our holographic measurement.     

Cosmological natural selection and the purpose of the universe

The cosmological natural selection (CNS) hypothesis holds that the fundamental constants of nature have been fine‐tuned by an evolutionary process in which universes produce daughter universes via the formation of black holes. Here, we formulate the CNS hypothesis using standard mathematical tools of evolutionary biology. Specifically, we capture the dynamics of CNS using Price's equation, and we capture the adaptive purpose of the universe using an optimization program. We establish mathematical correspondences between the dynamics and optimization formalisms, confirming that CNS acts according to a formal design objective, with successive generations of universes appearing designed to produce black holes. © 2013 Wiley Periodicals, Inc. Complexity 18: 48–56, 2013     

Flooded countercurrent two-phase flow in horizontal tubes and channels

A criterion for flooding in the countercurrent flow of two fluids in horizontal tubes and channels is developed. It exhibits a dependence upon the density ratio of the fluids beyond that present in the criterion of Wallis (1969). Experiments were carried out with air and water in a horizontal tube at atmospheric pressure and these, together with others reported in the literature, are shown to be in fair agreement with the prediction of the criterion, though it is emphasised that more experimental work is desirable.Work reported in the literature with miscible fluids with a density ratio close to unity confirms the extra dependence upon the density ratio.     

Total and partial photoionization cross-sections of O2 from 100 to 800 Å

The branching ratios and absolute values of the total and partial photoionization cross-sections for producing O₂⁺ in its various electronic states are given as a function of wavelength in the range 100–800 Å. Cross-sections for dissociative ionization are given based on the premise that some of the bound ionic states predissociate. Photoelectron spectroscopy and absorption techniques utilizing a double ionization chamber were used to obtain the data.     

Zero temperature magnetization of a one-dimensional spin glass

We calculate the zero temperature magnetizationm of a one-dimensional Ising spin glass is a weak magnetic fieldh. We show thatmCh _x and give closed expressions for the constantC and the exponentx which both depend on the probability distribution of nearest-neighbor interactions.     

Approaches to calibration in GFAAS: Direct or standard additions

Summary The performance of standard additions calibration is compared with direct calibration against standards. Computer simulation is used to provide information on the reduction of the useful analytical range associated with the use of standard additions. Provided that interference control measures necessary for direct calibration do not themselves degrade performance, the range over which acceptable precision is likely to be obtained will be reduced to between one third and one quarter ofthat attainable using direct calibration. Details of the usefulness of simple quality control measures which can be used in conjunction with standard additions are presented and their limitations are discussed. The conditions most favourable to the use of standard additions are outlined.

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Eichverfahren bei der GFAAS: Direkt oder Standardzugaben

     

A systematic approach to quantitation of ephedra alkaloids in natural health products

A method for accurate determination of ephedrine (E) alkaloids in natural health products (NHP) is described. The NIST dietary supplement standard reference materials (SRMs) were selected for these studies. These SRMs comprise ground Ma Huang herb (Ephedra sinica Stapf.), a spray dried extract of the former, and commercial formulations derived from gel caps and a protein drink. The efficiency of sonication-assisted extraction and Soxhlet extraction was studied using both ammonium formate and potassium phosphate in 3% methanol as extraction media. The efficiency of SPE clean-up of the extract deteriorated rapidly when increasing amounts of sample matrix or analyte were processed, because of limited cartridge capacity. Quantitation by the method of additions was required to ensure the highest accuracy using both LC–UV and ES–LC–MS–MS techniques. Whereas the LC–UV method is more convenient and precise, the results are more questionable than ES–LC–MS–MS, because species-specific detection is not possible.     

High-performance semiconducting polythiophenes for organic thin-film transistors

Conjugated polymers have been widely studied as potential semiconductor materials for organic thin-film transistors (TFTs). However, they have provided functionally poor transistor properties when the TFTs are fabricated in air. We have developed a class of liquid crystalline regioregular polythiophenes, PQTs, that possess sufficient air stability to enable achievement of excellent TFT properties under ambient conditions. These polythiophenes exhibit unique self-assembly ability and form highly structured thin films when deposited from solution under appropriate conditions. TFTs fabricated in air with PQT channel layers have provided high field-effect mobility to 0.14 cm2 V-1 s-1 and high current modulation to over 107, together with other desirable transistor properties. These high-performance polythiophenes will therefore help bring the long-standing concept of low-cost organic/polymer transistor circuits closer to commercial reality.     

Synthesis of 2,3-dihydrospiro[benzofuran-2,4′ -piperidines] and 2,3-dihydrospiro[benzofuran-2,3′-pyrrolidines]

The synthesis of 2,3-dihydrospiro[benzofuran-2,4′-piperidines] 3 and 2,3-dihydrospiro[benzofuran-2,3′]-pyrrolidine] 6 is described. The synthesis was achieved by a Grignard reaction of a 2-fluorobenzylhalide with an appropriate cycloazaalkyl ketone to yield the tertiary alcohols 1 and 4 . Subsequent intramolecular displacement of the aromatic fluoride by the derived alkoxides provided the novel system. Nitration of 1′-acetyl-2,3-dihydrospiro[benzofuran-2,4′-piperidine] 7 resulted in a 5-nitro derivative.