A rapid and economical method for profiling feature heights during microfabrication

Quality control is an important and integral part to any microfabrication process. While the widths of features often can be easily assessed by light microscopy, the heights of the fabricated structures are more difficult to determine. Here, we present a rapid, accurate, and low-cost method to measure the heights of microfabricated structures during and after the fabrication process. This technique is based on white-light interferometry, which offers accuracy on the submicrometre scale.     

The proton relaxation of CH3OD in the presence of Co(II) ions,as studied by spin-echo techniques

By measurement of the proton relaxation times T ₁ and T ₂ of CH₃OD containing Co⁺⁺ ions in dilute solution and the dependence of the observed decay time (T ₂ ^?) on t _ep the separation between pulses in a Carr-Purcell sequence the coordination number is shown to be six. Since this result has previously been obtained by an independent method, the use of the dependence of T ₂ ^? on t _ep to determine coordination numbers is justified for solutions of paramagnetic ions. The validity of analytical expressions derived previously has been checked by numerical methods, and the analytical expression is shown to be valid even in the presence of H ₀ and H ₁ inhomogeneity and inaccurate pulses of finite duration, provided that the Meiboom-Gill method is used. In an Appendix insight derived from the results of the numerical solutions is used to give a brief derivation of the dependence of T ₂ ^? on H ₀, exchange rate and t _ep.     

An investigation of the changes in the natural frequency of a pile affected by scour

Scour around bridge foundations is one of the leading causes of bridge failure. Up until recently, the monitoring of this phenomenon was primarily based around using underwater instrumentation to monitor the progression of scour holes as they develop around foundation systems. Vibration-based damage detection techniques have been used to detect damage in bridge beams. The application of these vibration based methods to the detection of scour has come to the fore in research in recent years. This paper examines the effect that scour has on the frequency response of a driven pile foundation system, similar to those used to support road and rail bridges. The effect of scour on the vibration characteristics of the pile is examined using laboratory and field testing. It is clear that there is a very clear reduction in the natural frequency of the pile as the severity of scour increases. It is shown that by combining state-of-the-art geotechnical techniques with relatively simple finite element modelling approaches, it is possible to accurately predict the natural frequency of the pile for a given scour depth. Therefore, the paper proposes a method that would allow the estimation of scour depth for a given observed pile frequency.     

Higgs boson searches at the Tevatron

This article reviews the Higgs searches at the Tevatron, as presented over the summer of 2012; both standard model (SM) and beyond the standard model (BSM) results are discussed as detailed (arXiv: 1207.0449; Phys. Rev. Lett., 2012, 109: 071804; Phys. Rev. D, 2012, 85: 032005). We discuss the combination of searches by the CDF and D0 Collaborations for the standard model Higgs boson in the mass range 100–200 GeV/c ² produced in the the gg → H, WH, ZH, t{ie27-1}H, and vector boson fusion production modes, and decaying in the H → b{ie27-2}, H → W ⁺ W ^?, H → ZZ, H → τ ⁺ τ ^?, and H → γγ modes. The data, collected at the Fermilab Tevatron collider in p{ie27-3} collisions at {ie27-4} TeV, correspond to integrated luminosities of up to 10 fb^?1. In the absence of signal, we expect to exclude the regions 100<m _H < 120 GeV/c ² and 139<m _H < 184 GeV/c ². We exclude, at the 95% C.L., two regions: 100<m _H < 103 GeV/c ², and 147<m _H < 180 GeV/c ². We observe a significant excess of events in the mass range between 115 and 140 GeV/c ². The local significance corresponds to 3.0 standard deviations at m _H = 120 GeV/c ²; the global significance (incorporating the look-elsewhere effect) for such an excess anywhere in the full mass range investigated is approximately 2.5 standard deviations. Furthermore, we separately combine searches for H → b{ie27-5}, H → W+W ^? and H → γγ. We find that the excess is concentrated in the H → b{ie27-6} channel, appearing in the searches over a broad range of m _H ; the maximum local significance of 3.3 standard deviations corresponds to a global significance of approximately 3.1 standard deviations. The observed signal strengths in all channels are consistent with the expectation for a standard model Higgs boson at m _H = 125 GeV/c ². The production of neutral Higgs bosons in association with b-quarks can be significantly enhanced in various beyond the standard model scenarios, including Supersymmetry. The recent combination of such searches from the two collaborations is discussed.     

Growth and optical characterization of organic nonlinear optical crystal: indole-3-aldehyde

The metastable zone width for the solution of organic nonlinear material: indole-3-aldehyde (IA) has been determined for the various solvents of acetone, methanol and ethyl acetate and the corresponding IA crystals have been grown by temperature lowering technique. The surface analysis on different planes of the grown crystals has been carried out. The range of transmission and powder second harmonic generation efficiency of IA have been reported.     

A mild and highly convenient chemoselective alkylation of thiols using Cs2CO3-TBAI

A mild and improved method for the synthesis of thioethers has been developed. In the presence of cesium carbonate, tetrabutylammonium iodide, and DMF, various alkyl and aryl thiols underwent S-alkylation to afford structurally diverse sulfides in high yield. Unprotected mercaptoalcohols and thioamines reacted chemoselectively at the sulfur moiety exclusively. An example of a one-pot, solid-phase synthesis of a thioether is also described.     

Synthesis and characterization of 7-(CH3)3N-4- {2,4-(NO2)2C6H3S}-nido-7-CB10H11 and its Biodistribution in C57B16 Mice Bearing B16 Melanoma

7-(CH₃)₃N-4-{2,4-(NO₂)₂C₆H₃S}-nido-7-CB₁₀H₁₁ has been synthesized through a Friedel-Crafts substitution reaction on 7-(CH₃)3N-nido-7- CB₁₀H₁₂. A biodistribution study in mice with implanted B16 melanoma indicates that the compound locates in neoplastic tissue at concentrations which suggest that its use in ¹⁰B neutron capture therapy may be feasible.     

Isolement et identification de composés phénoliques et monoterpéniques de la mousse de chêne (Evernia prunastri (L.) Ach.)

The composition of different oakmoss extracts was investigated by combined gas chromatography/mass spectrometry. A series of 38 compounds – especially phenol derivatives and monoterpenes – was identified, 22 of which have not yet been reported as constituents of oakmoss.