On-line Partial Discharge Localization of 10-kV Covered Conductor Lines

This paper proposes an innovative partial discharge (PD) location technique for overhead electrical power distribution networks. It is aimed at improving the condition-based maintenance of the network. PD localization is carried out via an improved double-sided traveling-wave method. The method is driven by a hybrid detection technique, which integrates a pulse-based synchronization mechanism and a global positioning system (GPS). The proposed solution offers a number of benefits. It has the nice inherent feature of being immune to varying physical parameters of the transmission line, and it has been proven be offer improved accuracy with respect of the conventional GPS-based location methods. Also, an in-house designed portable and non-invasive test setup is presented and thoroughly discussed, thus demonstrating the feasibility of the proposed method. Moreover, an enhanced algorithm is embedded into the PD location system to improve robustness to high-level noise. Finally, the proposed tool relies on a well-established automatic procedure which requires neither parameter tuning nor any expert intervention. The features and strengths of the method are validated on a real case consisting of a 2125-m long 10-kV overhead covered conductor line

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Highly Selective Fluorescent Recognition of Sulfate in Water by Two Rigid Tetrakisimidazolium Macrocycles with Peripheral Chains

The reinforced molecular recognition of two rigid tetrakisimidazolium macrocycles resulted in highly selective fluorescent recognition of sulfate dianion in water with an unprecedentedly high association constant of 8.6 × 10⁹ M^–2. Besides the electrostatic interaction, the single crystal X-ray analysis revealed that sulfate was encapsulated in a pseudohexahedral cavity of a sandwich structure by two orthogonally packed macrocycles via eight hydrogen bonds between the C2 hydrogen atoms of the imidazolium units and the oxygen atoms of sulfate. This sandwich structure was reinforced by the π–π stacking between the phenyl and the triazinonide rings and multiple charge-assisted hydrogen bonds between the peripheral chains and the rigid backbones. Notably, these peripheral-backbone hydrogen bonds rendered the flexible peripheral chains to coil around the sandwich structure to shield sulfate inaccessible to water. This binding process was visible by fluorescence enhancement, which was attributed to a restrained rotation and better conjugation of the macrocycle backbone upon binding to sulfate

Friedel–Crafts-Type Allylation of Nitrogen-Containing Aromatic Compounds with Allylic Alcohols Catalyzed by a [Mo₃S₄Pd(η³-allyl)] Cluster

With the direct use of allylic alcohols as allylating agents, the Friedel–Crafts-type allylic alkylation of nitrogen-containing aromatic compounds catalyzed by a [Mo₃S₄Pd­(η³-allyl)] cluster is achieved. With a 3 mol % catalyst loading in acetonitrile at reflux or 60 °C, a variety of <i>N</i>,<i>N</i>-dialkylanilines and indoles reacted smoothly with allylic alcohols to afford the Friedel–Crafts-type allylation products in good to excellent yields with high levels of regioselectivity

Highly Selective Fluorescent Recognition of Sulfate in Water by Two Rigid Tetrakisimidazolium Macrocycles with Peripheral Chains

The reinforced molecular recognition of two rigid tetrakisimidazolium macrocycles resulted in highly selective fluorescent recognition of sulfate dianion in water with an unprecedentedly high association constant of 8.6 × 10⁹ M^–2. Besides the electrostatic interaction, the single crystal X-ray analysis revealed that sulfate was encapsulated in a pseudohexahedral cavity of a sandwich structure by two orthogonally packed macrocycles via eight hydrogen bonds between the C2 hydrogen atoms of the imidazolium units and the oxygen atoms of sulfate. This sandwich structure was reinforced by the π–π stacking between the phenyl and the triazinonide rings and multiple charge-assisted hydrogen bonds between the peripheral chains and the rigid backbones. Notably, these peripheral-backbone hydrogen bonds rendered the flexible peripheral chains to coil around the sandwich structure to shield sulfate inaccessible to water. This binding process was visible by fluorescence enhancement, which was attributed to a restrained rotation and better conjugation of the macrocycle backbone upon binding to sulfate

Tandem Rh-Catalyzed [4 + 2] Vinylic C–H <i>O</i>‑Annulation of Exocyclic Enones with Alkynes and 1,5‑H Shift

Active pyrylium intermediates are in situ generated by a Rh-catalyzed vinylic C–H annulation reaction between exocyclic α,β-enones and alkynes, which undergo a base-promoted rearrangement via 1,5-H shift to form 1<i>H</i>-benzo­[<i>f</i>]­chromene derivatives

Cascade C–H Annulation of Aldoximes with Alkynes Using O₂ as the Sole Oxidant: One-Pot Access to Multisubstituted Protoberberine Skeletons

A cascade double C–H annulation of aldoximes with alkynes to produce benz­[<i>a</i>]­acridizinium salts is developed by using a simple catalytic system of [Cp*Rh­(OAc)₂]₂ in the presence of Zn­(OTf)₂ with oxygen as the sole oxidant. In addition, the challenging C–H annulation of aldoximes with alkynes, especially arylalkynes, to synthesize 1<i>H</i>-isoquinolines is also achieved under slightly modified conditions. This protocol provides an efficient one-pot access to multisubstituted dehydroberberinium skeletons from simple starting materials, which can be easily transformed into berberinium and tetrahydroberberine skeletons by controlled hydrogenation

Room-Temperature Coupling/Decarboxylation Reaction of α‑Oxocarboxylates with α‑Bromoketones: Solvent-Controlled Regioselectivity for 1,2- and 1,3-Diketones

A transition-metal-free and room-temperature coupling/decarboxylation reaction between α-oxocarboxylates and α-bromoketones is reported herein. It represents the first mild and regioselective synthesis of either 1,2- or 1,3-diketones from the same starting materials. Notably, the regioselectivity is simply controlled by solvents. The preliminary experimental data and DFT calculations suggest sequential Darzens-type coupling, alkaline hydrolysis, KOH-promoted oxirane opening and decarboxylation in one pot. This method is efficient for the synthesis of α,β-epoxy-γ-butyrolactone and curcuminoids

Room-Temperature Coupling/Decarboxylation Reaction of α‑Oxocarboxylates with α‑Bromoketones: Solvent-Controlled Regioselectivity for 1,2- and 1,3-Diketones

A transition-metal-free and room-temperature coupling/decarboxylation reaction between α-oxocarboxylates and α-bromoketones is reported herein. It represents the first mild and regioselective synthesis of either 1,2- or 1,3-diketones from the same starting materials. Notably, the regioselectivity is simply controlled by solvents. The preliminary experimental data and DFT calculations suggest sequential Darzens-type coupling, alkaline hydrolysis, KOH-promoted oxirane opening and decarboxylation in one pot. This method is efficient for the synthesis of α,β-epoxy-γ-butyrolactone and curcuminoids