Minimally‐invasive Microneedle‐based Biosensor Array for Simultaneous Lactate and Glucose Monitoring in Artificial Interstitial Fluid

Here we report the first mediated pain free microneedle‐based biosensor array for the continuous and simultaneous monitoring of lactate and glucose in artificial interstitial fluid (ISF). The gold surface of the microneedles has been modified by electrodeposition of Au‐multiwalled carbon nanotubes (MWCNTs) and successively by electropolymerization of the redox mediator, methylene blue (MB). Functionalization of the Au‐MWCNTs/polyMB platform with the lactate oxidase (LOX) enzyme (working electrode 1) and with the FAD‐Glucose dehydrogenase (FADGDH) enzyme (working electrode 2) enabled the continuous monitoring of lactate and glucose in the artificial ISF. The lactate biosensor exhibited a high sensitivity (797.4±38.1 μA cm^?2 mM^?1), a good linear range (10–100 μM) with a detection limit of 3 μM. The performance of the glucose biosensor were also good with a sensitivity of 405.2±24.1 μA cm^?2 mM^?1, a linear range between 0.05 and 5 mM and a detection limit of 7 μM. The biosensor array was tested to detect the amount of lactate generated after 100 minutes of cycling exercise (12 mM) and of glucose after a normal meal for a healthy patient (10 mM). The results reveal that the new microneedles‐based biosensor array seems to be a promising tool for the development of real‐time wearable devices with a variety of sport medicine and clinical care applications.     

A simple and readily integratable approach to toxicity prediction

A simple, highly extensible computational strategy to assess compound toxicity has been developed with the premise that a compound's toxicity can be gauged from the toxicities of structurally similar compounds. Using a reference set of 13645 compounds with reported acute toxicity endpoint dose data (oral, rat-LD(50) data normalized in mg/kg), a generic utility which assigns a compound the average toxicity of structurally similar compounds is shown to correlate well with reported values. In a leave-one-out simulation using the requirement that at least one structurally similar member in a "voting consortium" is present within a reference set, the strategy demonstrates a predictive correlation (q wedge 2) of 0.82 with 57.3% of the compounds being predicted. Similar leave-one-out simulations on a set of 1781 drugs demonstrate a q wedge 2 of 0.74 with 51.8% of the compounds being predicted. Simulations to optimize similarity cutoff definitions, consortium member size, and reference set size illustrate that a significant improvement in the quality and quantity of predictions can be obtained by increasing the reference set size. Similar application of the strategy to subchronic and chronic toxicity data should be possible given reasonably sized reference sets.     

Determination of stoichiometry of cadmium telluride by XPS

Summary The stoichiometry of cadmium telluride has been determined by the non-destructive technique of XPS. The determination has been based on differential photoionisation cross-sections, electron mean free paths and areas due to M₅ electrons of Cd and Te. The stoichiometry of Cd and Te determined by XPS has been found to be in good agreement with that obtained by analysing Cd and Te independently by chemical methods.     

Physical parameters for atomic inner‐shell photoionization processes and analytical applications: a status report

The atomic inner‐shell vacancy decay processes comprising of radiative and non‐radiative transitions are characterized by the physical parameters, namely, the photoionization cross‐sections; X‐ray, Auger and Coster–Kronig (CK) transition rates; fluorescence and CK yields; and the vacancy transfer probabilities. These parameters are required to calculate the K‐shell and L_i (i = 1–3)/M_i (i = 1–5) sub‐shell X‐ray production cross‐sections and relative intensities which, in turn, are needed for different analytical applications. This report intended to provide a detailed account of the currently available data sets of different physical parameters for use in various analytical applications. Copyright © 2011 John Wiley & Sons, Ltd.     

Catalytic effect of bases in impregnation of guanidine nitrate on Poplar (<Emphasis Type="Italic">Populus</Emphasis>) wood

Wood, one of the flammable material, was treated with aqueous solution of guanidine nitrate (GUN) and also with small amount of bases like N,N-dimethylformamide, 4-dimethylaminopyridine, pyridine, and triethylamine in the treating solution. These bases catalyze the impregnation of GUN as indicated by increase in mass gain percentage, elemental analysis, and scanning electron microscopy. To study their thermal behavior, dynamic thermogravimetry (TG) and derivative thermogravimetry (DTG) analysis under nitrogen atmosphere have been applied from ambient temperature to 973 K on all samples, at multiple linear heating rates 2.5, 5, 10, and 20 K min⁻¹. Non-isothermal, “model free” iso-conversional multiple heating rate methods, Ozawa–Flynn–Wall (O–F–W) and modified Coats–Redfern are used to calculate activation energy of samples. The activation energy of samples is found in the range 109–208 kJ mol⁻¹. Thermal parameters like overall pyrolysis duration, maximum mass loss rate, corresponding to DTG peak maximum and percentage char yield calculated at 873 K from TG curves are used to appraise the flammability of samples. Also, flammability of samples is determined by reliable methods namely limiting oxygen index and underwriters laboratories 94 (UL 94) test. The aforesaid study indicates that base catalyzed impregnated samples are less flammable than those impregnated with only GUN and untreated ones.     

Depth profiling of oxygen in oxide films by 18O(p,α)15N nuclear reaction analysis

The paper describes the determination and depth profiling of oxygen in thin oxide films using ¹⁸O(p,??)¹⁵N nuclear reaction. The excitation function of ¹⁸O(p,??)¹⁵N nuclear reaction exhibits a resonance at 629?keV and a plateau at 730?keV with uniform cross-section. The resonance is used to determine the depth profile of oxygen in films while the plateau, to estimate its overall concentration. The resonance, characterized by a width of 2.1?keV enables high-depth resolution (~20?nm) measurements and has a probing depth of more than a micron. The paper presents depth profile measurements of oxygen in several metal oxide films (SiO₂, TiO₂ and HfO₂) using this resonance. Possible interferences arising from ¹⁵N(p,??)¹²C, ¹⁹F(p,??)¹⁶O and ¹¹B(p,??)2?? nuclear reactions are also discussed. It has been shown that it can serve as a suitable alternative to 3.05?MeV ¹⁶O(??,??)¹⁶O resonant scattering which is generally used for depth profiling oxygen. It is, in fact, more reliable and precise in materials that witness significant large angle multiple scattering. It can also be advantageously used to monitor ¹⁸O, when used as a tracer.     

Synthesis and reactivity of new mono- and dinuclear niobium and tantalum imido complexes: X-ray crystal structure of [Ta(η-C5H4SiMe3)Cl2{NC6Me4-4-(N(SiMe3)2)}]

The reaction of [1,4-{SiMe₃(H)N}₂C₆Me₄] (1) with 2 equivalents of LiBuⁿ followed by the addition of SiMe₃Cl gave the diamine compound [1,4-{(SiMe₃)₂N}₂C₆Me₄] (2). [Ta(η⁵-C₅H₄SiMe₃)Cl₄] reacts with 2, in a 2:1 stoichiometric ratio, to initially yield a mixture of the dinuclear, [{Ta(η⁵-C₅H₄SiMe₃)Cl₂}₂(μ-1,4-NC₆Me₄N)] (3), and mononuclear, [Ta(η⁵-C₅H₄SiMe₃)Cl₂{NC₆Me₄-4-(N(SiMe₃)₂)}] (4), imido complexes. 3 can be obtained exclusively by submitting the reaction mixture to repeated cycles of evacuation, to remove volatiles, followed by addition of solvent and subsequent heating. The mononuclear imido complex 4 was isolated from the reaction of [Ta(η⁵-C₅H₄SiMe₃)Cl₄] with 2 in a 1:1 stoichiometric ratio. The molecular structure of 4 was determined by X-ray diffraction studies. [TaCl₃(CH₃CN)₂{NC₆Me₄-4-(N(SiMe₃)₂)}] (5) has been prepared by the reaction of one molar equivalent of TaCl₅ with 2 in a CH₃CN/CH₂Cl₂ solvent mixture. The synthesis of the niobium complexes, [{Nb(η⁵-C₅H₄SiMe₃)Cl₂}₂(μ-1,4-NC₆Me₄N)] (6) and [Nb(η⁵-C₅H₄SiMe₃)Cl₂{NC₆Me₄-4-(N(SiMe₃)₂)}] (7), was achieved in a similar manner to their tantalum analogues. The reactivity of 7 towards nucleophilic reagents, namely lithium benzamidinate, lithium (trimethylsilyl)cyclopentadienyl or lithium dimethylamide, has been studied and the following compounds prepared:[Nb(η⁵-C₅H₄SiMe₃)RCl{NC₆Me₄-4-(N(SiMe₃)₂)}] (R = η⁵-C₅H₄SiMe₃ (8), PhC(NSiMe₃)₂ (9), NMe₂ (10)). In an attempt to form the hetero bimetallic complex, [{Nb(η⁵-C₅H₄SiMe₃)Cl₂}(μ-1,4-NC₆Me₄N){Ta(η⁵-C₅H₄SiMe₃)Cl₂}] (11), the reaction of 7 with [Ta(η⁵-C₅H₄SiMe₃)Cl₄] has been studied. Analysis of the reaction products showed that 11 may exist in equilibrium with the homo bimetallic complexes 3 and 6.     

A graph search algorithm for indoor pursuit/evasion

Using concepts from both robotics and graph theory, we formulate the problem of indoor pursuit/evasion in terms of searching the nodes of a graph for a mobile evader. We present the IGNS (Iterative Greedy Node Search) algorithm, which performs offline guaranteed search (i.e. no matter how the evader moves, it will eventually be captured). Furthermore, the algorithm produces an internal search (the searchers move only along the edges of the graph; “teleporting” is not used) and exploits non-monotonicity, extended visibility and finite evader speed to reduce the number of searchers required to clear an environment. We present search experiments for several indoor environments, in all of which the algorithm succeeds in clearing the graph (i.e. capturing the evader).