A new microtensile tester for the study of MEMS materials with the aid of atomic force microscopy

An apparatus has been designed and implemented to measure the elastic tensile properties (Young's modulus and tensile strength) of surface micromachined polysilicon specimens. The tensile specimens are “dog-bone” shaped ending in a large “paddle” for convenient electrostatic or, in the improved apparatus, ultraviolet (UV) light curable adhesive gripping deposited with electrostatically controlled manipulation. The typical test section of the specimens is 400 μm long with 2 μm×50 μm cross section. The new device supports a nanomechanics method developed in our laboratory to acquire surface topologies of deforming specimens by means of Atomic Force Microscopy (AFM) to determine (fields of) strains via Digital Image Correlation (DIC). With this tool, high strength or non-linearly behaving materials can be tested under different environmental conditions by measuring the strains directly on the surface of the film with nanometer resolution.     

Photooxidation of aryl alkanes by a decatungstate/triethylsilane system in the presence of molecular oxygen

Decatungstate photocatalyzes the oxidation of aryl alkanes to the corresponding tertiary hydroperoxides and alcohols, in the presence of molecular oxygen. The addition of triethylsilane to the reaction mixture substantially increases the proportion of hydroperoxide formed.     

Energy considerations for topology-unaware TDMA MAC protocols

Since the energy budget of mobile nodes is limited, the performance of a networking protocol for such users should be evaluated in terms of its energy efficiency, in addition to the more traditional metrics such as throughput. In this paper, two topology-unaware MAC protocols—in which the scheduling time slots are allocated irrespectively of the underline topology—are considered and their energy consumption is derived. It turns out that the per frame power consumption is lower for the less throughput-efficient protocol, suggesting that energy savings are achieved at the expense of throughput.A finer energy consumption study is carried out in the sequel, focusing on the amount of energy consumed to successfully transmit a certain number of packets, or equivalently, on the per successful transmission power consumption. It is shown that the more throughput-efficient protocol consumes less energy per successful transmission under certain conditions (which are derived), due to the lower number of transmission attempts before a data packet is successfully transmitted. The same energy-efficiency relation is observed under certain conditions (which are derived) when data packets are delay constrained and, thus, may become obsolete if not transmitted successfully within a specific time interval. The conditions under which the per successful transmission power consumption is minimized for delay-constrained packets, are also established in this work and it is observed that when the system throughput is maximized, the power consumed is close to the minimum. Simulation results support the claims and the expectations of the aforementioned analysis.     

A unifying local-semilocal convergence analysis and applications for two-point Newton-like methods in Banach space

We provide a local as well as a semilocal convergence analysis for two-point Newton-like methods in a Banach space setting under very general Lipschitz type conditions. Our equation contains a Fréchet differentiable operator F and another operator G whose differentiability is not assumed. Using more precise majorizing sequences than before we provide sufficient convergence conditions for Newton-like methods to a locally unique solution of equation F(x)+G(x)=0. In the semilocal case we show under weaker conditions that our error estimates on the distances involved are finer and the information on the location of the solution at least as precise as in earlier results. In the local case a larger radius of convergence is obtained. Several numerical examples are provided to show that our results compare favorably with earlier ones. As a special case we show that the famous Newton-Kantorovich hypothesis is weakened under the same hypotheses as the ones contained in the Newton-Kantorovich theorem.     

Engset multi‐rate state‐dependent loss models with QoS guarantee

We consider a single link loss system of quasi‐random input, described by the Engset multirate loss model (EnMLM). Blocked calls may once reattempt to be connected to the system requiring less bandwidth; then the system is described by the single retry model for finite sources (f‐SRM). The EnMLM and the f‐SRM are extended with the single threshold finite source model (f‐STM), where calls may attempt to be connected to the system with less bandwidth requirements, according to the link occupancy, before blocking occurs. We focus on CBP equalization in the EnMLM, f‐SRM and f‐STM, under the bandwidth reservation (BR) policy. For this analysis, we apply two approximate methods, the Roberts' method and the method of reverse transition rates (RTR), which lead to a recursive CBP calculation. We evaluate the accuracy of the above models under the BR policy by comparing the analytical with simulation CBP results, based on the relative approximation errors (RAE). The results are highly satisfactory because they show that the proposed models (formulas) lead to small RAE. Copyright © 2005 John Wiley & Sons, Ltd.     

A 1,8-naphthalenediol-based unsymmetrical dinucleating ligand

A facile synthesis of 2-formyl-1,8-naphthalenediol is reported. Its potential as a general precursor for the preparation of unsymmetrical multidentate chelating ligand systems based on 1,8-naphthalenediol is demonstrated by the synthesis of the dinucleating ligand L(4-)(H(4)L=N,N'-bis(2-(1,8-naphthalenediol)methylidene)propylenediamine). Reaction of H(4) L with copper acetate results in the formation of the unsymmetrical dinuclear Cu(II) complex [LCu(2)](3), which has been structurally characterized by single-crystal X-ray diffraction. One Cu(II) ion is coordinated by a N(2)O(2) compartment of L(4-) and the other Cu(II) ion is coordinated by an O(4) compartment of L(4-) while they are bridged by two aryloxide functions of L(4-). A dimerization of two molecules of 3 to a tetranuclear entity 3(2) occurs through formation of weak apical Cu--O interactions. Analysis of the temperature dependent magnetic susceptibility measurements (2--290 K) established a strong intradimer exchange coupling J(12)=-371 cm(-1). This strong superexchange interaction fits nicely in a magneto-structural correlation which has been established for dinuclear bis(phenoxide)-bridged Cu(II) complexes demonstrating the electronic equivalence of the aryloxides of a phenol and 1,8-naphthalenediol.     

Reactions of Molecules with Two Equivalent Functional Groups. 5. Anomalous Reactivity of 1,10-Cyclooctadecanedione. Crystal and Molecular Structures of cis,cis-1,10-Diphenyl-1,10-cyclooctadiene and the Stereoisomers of 1,10-Diphenyl-1,10-cyclooctadecanediol(1)

The reaction of the title diketone (3) with phenyl Grignard produces (with rate constant k(1)) the conjugate base (6-M) of 10-hydroxy-10-phenylcyclooctadecanone (6), which is subsequently converted (with rate constant k(2)) to the conjugate base of the title diol, as a mixture of the cis (7, 55%) and trans (8, 45%) isomers. The ratio k(2)/k(1), 2.2 +/- 0.4, indicates that the carbonyl group in 6-M is 4.4 times as reactive as each carbonyl in 3. Competition experiments further demonstrate that the relative rates (per carbonyl) for addition of phenylmagnesium bromide to 3, 10-methylenecyclooctadecanone (11), and cyclopentadecanone (12) are 1.0:0.60:1.92. Possible reasons for this order of reactivity are discussed. Diols 7 and 8 undergo facile double dehydration to form the title diene 13, which is predicted by molecular mechanics calculations to be the most stable of the four possible symmetrical diene isomers. The structures of 7, 8, and 13 were secured by single-crystal X-ray studies.