A new synthesis of pyrazolo[1,5-d][1,2,4]triazines from pyrazolecarboxylic acid hydrazides and carbonyl compounds. I

Pyrazolo[1,5-d][1,2,4]triazines were synthesized from pyrazolecarboxylic acid hydrazides and carbonyl compounds. Pyrazolecarboxylic acid N-phenylhydrazide (1c) and formaldehyde gave not only the expected 4hn but 5 , respectively. The methyl substituted hydrazides with acetone afforded hydrazones, pyrazolotriazines or 13 depending on the position of the substituents. The reduction of both products yielded pyrazolecarboxylic acid hydrazides.     

Magnetic Titanium Dioxide Nanocomposites for Surface‐Enhanced Resonance Raman Spectroscopic Determination and Degradation of Toxic Anilines and Phenols

Mesoporous M‐TiO₂ NCs, functionalized by PATP, can capture toxic anilines and phenols by azo coupling. Loading these nanodevices with Ag NPs offers the possibility for a sensitive quantitative determination of target compounds by SERRS spectroscopy, which allows multiplex detection because of the specific vibrational fingerprints. Sensitivity and selectivity can be further enhanced by concentrating the hybrid particles by an external magnet and compound‐specific binding (anilines versus phenols). The bound toxic compounds can be degraded by TiO₂‐assisted photocatalysis after removal of the loaded hybrid particles from the sample solution with an external magnet. The degradation process can be enhanced in the presence of plasmonic Ag nanostructures.     

A real-time monitoring approach for bivariate event data

Early detection of changes in the frequency of events is an important task in many fields, such as disease surveillance, monitoring of high-quality processes, reliability monitoring, and public health. This article focuses on detecting changes in multivariate event data by monitoring the time-between-events (TBE). Existing multivariate TBE charts are limited because they only signal after an event occurred for each of the individual processes. This results in delays (i.e., long time-to-signal), especially when we are interested in detecting a change in one or a few processes with different rates. We propose a bivariate TBE chart, which can signal in real-time. We derive analytical expressions for the control limits and average time-to-signal performance, conduct a performance evaluation and compare our chart to an existing method. Our findings showed that our method is an effective approach for monitoring bivariate TBE data and has better detection ability than the existing method under transient shifts and is more generally applicable. A significant benefit of our method is that it signals in real-time and that the control limits are based on analytical expressions. The proposed method is implemented on two real-life datasets from reliability and health surveillance.     

Rates of homogeneous ice nucleation in levitated H2O and D2O droplets

Rates of homogeneous nucleation of H2O droplets in a temperature range from 236.37 to 237.91 K and of D2O droplets from 241.34 to 242.33 K were measured. The single microdroplets consisted of pure H2O or D2O and were levitated in an electrodynamic balance. In comparison to H2O, D2O shows a stronger tendency to nucleate. Over the investigated temperature interval, D2O droplets need to be supercooled less by 1.1 K compared to H2O droplets in order to arrive at the same nucleation rate. This is in good agreement with the higher degree of intermolecular association in liquid D2O, a fact which has been well established previously both from theory and experimental studies.     

n-Propylpyridinium chloride-modified poly(dimethylsiloxane) elastomeric networks: preparation, characterization, and study of metal chloride adsorption from ethanol solutions

An n-propylpyridinium chloride-modified PDMS elastomeric network, PDMS/Py(+)Cl(-), was prepared from linear PDMS chains containing Si(CH(3))(2)OH end-groups cross-linked by 3-chloropropyltrimethoxysilane and posterior reaction with pyridine. PDMS/Py(+)Cl(-) material was structurally characterized by infrared spectroscopy (IR) and solid state (13)C and (29)Si NMR. Thermogravimetric analysis of the product showed good thermal stability, with the initial temperature of weight loss at 450 K. The ion-exchange capacity of the PDMS/Py(+)Cl(-) was 0.65 mmol g(-1). Metal halides, MCl(z) [M=Fe(3+), Cu(2+), and Co(2+)], were adsorbed by the modified solid from ethanol solutions as neutral species by forming the surface anionic complexes MCl(z+n)(n-). The nature of the anionic complex structure was proposed by UV-vis diffuse reflectance spectra. The species adsorbed were FeCl(-)(4), CuCl(2-)(4), and CoCl(2-)(4). The specific sorption capacities and the heterogeneous stability constants of the immobilized metal complexes were determined with the aid of computational procedures. The trend in affinities of PDMS/Py(+)Cl(-) for the metal halides were found to be FeCl(3)>CuCl(2) approximately CoCl(2).     

A simple protocol for Matrix Assisted Laser Desorption Ionization- time of flight-mass spectrometry (MALDI-TOF-MS) analysis of lipids and proteins in single microsamples of paintings

A simple protocol, based on Bligh–Dyer (BD) extraction followed by MALDI-TOF-MS analysis, for fast identification of paint binders in single microsamples is proposed. For the first time it is demonstrated that the BD method is effective for the simultaneous extraction of lipids and proteins from complex, and atypical matrices, such as pigmented paint layers. The protocol makes use of an alternative denaturing anionic detergent (RapiGest™) in order to improve efficiency of protein digestion and purification step. Detection of various lipid classes, such as triacylglycerols (TAGs) and phospholipids (PLs), and their oxidation by-products was accomplished, whereas proteins could be identified by peptide mass fingerprinting. The effect of pigments on ageing of lipids and proteins was also investigated.     

Microwave-assisted direct esterification of a cyclic phosphinic acid with phenols

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High Electromagnetic Field Enhancement of TiO2 Nanotube Electrodes

We present the fabrication of TiO₂ nanotube electrodes with high biocompatibility and extraordinary spectroscopic properties. Intense surface‐enhanced resonance Raman signals of the heme unit of the redox enzyme Cytochrome b₅ were observed upon covalent immobilization of the protein matrix on the TiO₂ surface, revealing overall preserved structural integrity and redox behavior. The enhancement factor could be rationally controlled by varying the electrode annealing temperature, reaching a record maximum value of over 70 at 475 °C. For the first time, such high values are reported for non‐directly surface‐interacting probes, for which the involvement of charge‐transfer processes in signal amplification can be excluded. The origin of the surface enhancement is exclusively attributed to enhanced localized electric fields resulting from the specific optical properties of the nanotubular geometry of the electrode.