Design of a Thin Film Infrared Barcode on a Flexible Substrate

We report the design, fabrication and characterization of an infrared barcode. This barcode is composed of a bilayer of titanium and amorphous silicon on a flexible Kapton substrate. Information encoded in the barcode shows high contrast when viewed with an infrared imaging system in the 8 to 12 m spectral region. The barcode information is concealed under visible viewing conditions, i.e., the barcode appears as an untreated, uniform metal sheet to a detector of visible radiation (400 to 700nm).     

Phosphoinositide signaling; from affinity probes to pharmaceutical targets

Lipid signaling by phosphoinositides (PIP(n)s) involves an array of proteins with lipid recognition, kinase, phosphatase, and phospholipase functions. Understanding PIP(n) pathway signaling requires identification and characterization of PIP(n)-interacting proteins. Moreover, spatiotemporal localization and physiological function of PIP(n)-protein complexes must be elucidated in cellular and organismal contexts. For protein discovery to functional elucidation, reporter-linked phosphoinositides or tethered PIP(n)s have been essential. The phosphoinositide 3-kinase (PI 3-K) signaling pathway has recently emerged as an important source of potential "druggable" therapeutic targets in human pathophysiology in both academic and pharmaceutical environments. This review summarizes the chemistry of PIP(n) affinity probes and their use in identifying macromolecular targets. The process of target validation will be described, i.e., the use of tethered PIP(n)s in determining PIP(n) selectivity in vitro and in establishing the function of PIP(n)-protein complexes in living cells.     

Catalytic construction and reconstruction of guanidines: Ti-mediated guanylation of amines and transamination of guanidines

Bis(guanidinate) titanium imido complexes [{(Me2N)C(NiPr)2}2TiNAr'] (Ar' = 2,6-Me2C6H3 (1a); C6F5 (1b)) are competent catalysts for the guanylation of a variety of arylamines with carbodiimide. The reversible [2 + 2] addition of iPrN=C=NiPr to 1b is demonstrated and is proposed to be part of the catalytic cycle. Compounds 1a and 1b are also effective precatalysts for the transamination of trialkylguanidines with arylamines to yield aryldialkylguanidines.     

Synthesis and molecular and extended structures for a diaminonaphthalene-derived bis(amido)stannylene

The cyclic bis(amido)tin(II) compound Sn[1,8-((iPrN)2C10H6] (2) was isolated from the reaction of Li2[1,8-((iPrN)2C10H6] (1) and SnCl2. Solid-state structural analysis of 2 showed it to be a mononuclear species with a pyramidal Sn center as part of a nonplanar metallaheterocycle. The packing diagram of 2 revealed an extended one-dimensional head-to-tail chain structure with short intermolecular Sn/arene-C interactions. Computational examination of 2 (DFT/PW91 and MP2 with 6-31G* and 6-311G** basis functions) indicated that the optimum gas-phase structure of 2,which displays a Sn center in the plane of the naphthyl backbone with a slightly twisted metallaheterocycle, is approximately 24 kcal/mol lower in energy than the X-ray structure. The solid-state geometry of 2 is attributed to the intermolecular donation of the naphthalene pi-electrons to a Lewis acidic Sn center, which leads to the observed supramolecular structure. The crystal structure of 1 is also reported.     

Transference numbers for anhydrous methanol solutions at 10 and 25°C

Transference numbers are reported for LiCl and NaCl in methanol at 25°C and for NaCl, KCl, and Bu₄NBr in methanol at 10°C. The potentiometric moving-boundary method as developed by Kay and Fratiello was employed to give a precision of about 0.05% and an accuracy of at least 0.1% as indicated by two independent determinations of the conductances of the Cl^– and Br^– ions. The data are extrapolated by the Fuoss-Onsager theory, and the magnitude of the electrophoretic effect is calculated as described by Kay and Dye. The agreement with this theory is quite good at both temperatures, although the å value required in the case of Bu₄NBr is considerably larger than that obtained from conductance data. This agreement contrasts with that obtained for ethanol and acetone solutions where the measured electrophoretic effect is considerably larger than the corresponding calculated values. The importance of this fact in the determination of ion-pair association constants is discussed.     

Determination of lactate in human saliva with an electrochemical enzyme probe

Electrochemical biosensors for lactate were assembled and used for the determination of lactic acid in saliva. Saliva was collected from healthy subjects and immediately screened for its lactate content. The electrochemical and biological interferences from saliva were discriminated by using a dual platinum electrode and blocking membranes. The stability, reproducibility and lifetime of the probe were studied. Lactate was measured in eight subjects in fasting conditions and after eating, showing an increase in lactate for each subject after meals. Correlation with a spectrophotometric lactate measurement is reported. Subjects before, during and after physical exercise showed consistent variations of lactate in saliva.     

The direct formation of ketones by reaction of methyl- and aryl-(carbonyl)(iodo)pentamethylcyclopentadienylrhodium complexes with organic iodides

[C₅Me₅Rh(aryl)(CO)I] reacts with methyl iodide to give [(C₅Me₅RhI₂)₂] and arylCOMe; similar reactions occur between [C₅Me₅Rh(Me)(CO)I] and RI to give the ketones RCOMe (R = Ph, Me, Et, or Pr).     

Integration of microbolometers with infrared microstrip antennas

We report on various integration schemes of infrared microbolometers with microstrip antennas. The first integration design consists of two gold (Au) rectangular microstrip patches coupled along the radiating edges by a narrow niobium (Nb) strip. Devices using silicon oxide are compared to devices using amorphous silicon as antenna substrate. An extension of the twin-patch detector design is the microstrip dipole antenna-coupled microbolometer. Two ways of connecting the device to the contact pads via narrow dc leads are presented and compared. The contribution of the dc leads to the detector response is eliminated by directly connecting the dipole to the contact pads. The thermal isolation of the microbolometer from the silicon wafer is improved by incorporating air into the antenna dielectric substrate. This leads to higher detector responsivity and shifts the resonance towards longer antennas. The implementation of a bridge microstrip dipole antenna structure is also discussed.     

Low-temperature behavior of specific heat curves in ruthenocuprate RuSr<Subscript>2</Subscript>Gd<Subscript>1.5</Subscript>Ge<Subscript>0.5</Subscript>Cu<Subscript>2</Subscript>O<Subscript>10 − δ</Subscript>: Superconducting,magnetic and crossing-point effects

Magnetic and superconducting properties of polycrystalline samples of RuSr₂Gd_1.5Ce_0.5Cu₂O_{(10 − δ)}, asprepared (by solid-state reaction) and annealed in pure oxygen at different pressure are presented. Specific heat and magnetization were investigated in the temperature range 1.8–300 K with a magnetic field up to 8 T. Specific heat, C (T), shows a jump at the superconducting transition (with onset at T ≈ 37.5 K) and a Schottky-type anomaly below 20 K. It is found that curves C(T) taken for different values of magnetic field have the same crossing point (at T _* ≈ 2.7 K) for all samples studied. At the same time, C(H) curves taken for different temperatures have a crossing point at a characteristic field H _* ≈ 3.7 T. These effects are manifestations of the crossing-point phenomenon, which is supposed to be inherent for strongly correlated electron systems.     

A single extraction method for the analysis by liquid chromatography/tandem mass spectrometry of fumonisins and biomarkers of disrupted sphingolipid metabolism in tissues of maize seedlings

The fungus Fusarium verticillioides is a pathogen of many plants and produces fumonisins. In addition to their well-studied animal toxicoses, these toxins contribute to the development of maize seedling disease in susceptible maize varieties. Fumonisin disruption of sphingolipid biosynthesis occurs during pathogenesis. An extraction method was developed for the simultaneous analysis of fumonisins B₁ (FB₁), B₂ (FB₂) and B₃ (FB₃), free sphingoid bases and sphingoid base 1-phosphates in maize tissues by liquid chromatography/linear ion trap tandem mass spectrometry. The method involved a single extraction using 1:1 acetonitrile:water + 5% formic acid (1 ml per 10 mg tissue). Mean recoveries ranged from approximately 50 to 99 percent, and limits of detection ranged from 10 fg μl⁻¹ to 6900 fg μl⁻¹. To test the efficacy of the method, seeds of a susceptible maize line were inoculated with a pathogenic, fumonisin-producing strain of F. verticillioides. The seedlings were then harvested, and fumonisin content, as well as sphingoid bases and their 1-phosphates, were measured in the leaf and root tissues. Fumonisin accumulation was significantly greater in leaf one compared to leaves two and three. While FB₁, FB₂, and FB₃ were detected in root tissues, FB₁ was preferentially accumulated in leaf tissues. Accumulation of sphingoid bases and their 1-phosphates was evident in roots and leaves of seedlings grown from inoculated seed, with the level of accumulation being similar in leaves 1, 2 and 3. The method developed was effective, fast, and sensitive for use in simultaneously measuring fumonisin in tissues and their effects on sphingolipid metabolite biomarkers of disease. The method should be useful for screening maize cultivars for susceptibility to F. verticillioides-induced seedling diseases. Figure Lesion with chromatography