Sorption of inorganic nanoparticles in woven cellulose fabrics

Titanium dioxide was deposited from aqueous suspension onto cellulosic surfaces.Titania was sourced from Degussa (P25TM,70:30 anatase:rutile).Dry uptake of particles was shown to be rapid and dominant with one-third of the deposition occurring in less than 30 s and over one-half in the first minute.Isotherms were recorded to compare the rate of titanium deposition on dry and pre-wetted cotton.In the dry case uptake reached a maximum in 30 min whereas in the pre-wetted case the uptake was seen to continue beyond 180 min.A broad trend of higher deposition occurring at lower pH was seen,corresponding to the region where surface charges were opposite and thus attractive.Dry pickup was less significant at high pH.The response to varying ionic strength was complex and was attributed to the combined effect of charge screening,particle aggregation and consequent particle entrapment or occlusion.Titania deposition into the interstices of woven cotton sheets resulted in the formation of inorganic,nanoparticulate skeletons which could be isolated by controlled combustion of the cellulose and thus cotton was suggested to have potential for the templated synthesis of high surface area semiconductor materials.     

Inclusive and exclusive measurements in the projectile breakup of 7Li

The inclusive and exclusive measurements were carried out for ⁷Li projectile breakup on ²⁷Al target at 48 MeV. In the inclusive data we have observed a broad peak around the beam velocity for alphas and tritons. The exclusive data for alpha-triton coincidences show good agreement with the post-form DWBA theory of breakup reactions.     

Approximation Algorithms for Pick-and-Place Robots

In this paper we study the problem of finding placement tours for pick-and-place robots, also known as the printed circuit board assembly problem with m positions on a board, n bins containing m components and n locations for the bins. In the standard model where the working time of the robot is proportional to the distances travelled, the general problem appears as a combination of the travelling salesman problem and the matching problem, and for m=n we have an Euclidean, bipartite travelling salesman problem. We give a polynomial-time algorithm which achieves an approximation guarantee of 3+. An important special instance of the problem is the case of a fixed assignment of bins to bin-locations. This appears as a special case of a bipartite TSP satisfying the quadrangle inequality and given some fixed matching arcs. We obtain a 1.8 factor approximation with the stacker crane algorithm of Frederikson, Hecht and Kim. For the general bipartite case we also show a 2.0 factor approximation algorithm which is based on a new insertion technique for bipartite TSPs with quadrangle inequality. Implementations and experiments on real-world as well as random point configurations conclude this paper.     

Variable Synthesis of Alcohols and Ketones Using the Grignard Method as a Form of MPVO Reaction

The unexpected occurrence of ketones 9 and 16 in addition to expected alcohols 5 and 15 in the synthesis of sesquiterpenes salsolenketone 1 and salsolene oxide 2 during Grignard reactions of the corresponding aldehydes with bromoalkenes under air‐ and water‐free conditions by the Meerwein–Ponndorf–Verley–Oppenauer reaction is reported. The product distribution could be influenced by the amounts of aldehyde used.     

Beiträge zur Theorie der elliptischen Funktionen

Ohne Zusammenfassung Auszug aus einem Schreiben an Herrn G. Mittag-Leffler.     

Fette, ?le

Ohne Zusammenfassung     

Charge inversion as a structural probe for C6H 5 + and C6H 6 +· cations

Charge reversal (⁺CR⁻) of cations to anions can be used to structurally differentiate isomeric C₆H₅⁺ and C₆H₆^+· hydrocarbon ions by means of tandem mass spectrometry. In view of the manifold of possible isomers, only a few prototype precursors are examined. Thus, charge inversion demonstrates that electron ionization of 2,4-hexadiyne yields an intact molecular ion, whereas the charge inversion spectra of C₆H₆^+· obtained from benzene, 1,5-hexadiyne, and fulvene are identical within experimental error. Similarly, the ⁺CR⁻ spectrum of the C₆H₅⁺ cation generated by dissociative ionization of 2,4-hexadiyne is significantly different from the ⁺CR⁻ spectrum of C₆H₅⁺ obtained from iodobenzene, suggesting the formation of a 2,4-hexadiynyl cation from the former precursor. Although charge inversion of cations to anions has a low efficiency and requires large precursor ion fluxes, the particular value of this method is that the spectra may not just differ in fragment ion intensities, but these differences can directly be related to the underlying ion structures.