Evaluation of borinic acids as new, fast hydrogen peroxide–responsive triggers

Hydrogen peroxide (H2O2) is responsible for numerous damages when overproduced, and its detection is crucial for a better understanding of H2O2-mediated signaling in physiological and pathological processes. For this purpose, various “off–on” small fluorescent probes relying on a boronate trigger have been prepared, and this design has also been involved in the development of H2O2-activated prodrugs or theranostic tools. However, this design suffers from slow kinetics, preventing activation by H2O2 with a short response time. Therefore, faster H2O2-reactive groups are awaited. To address this issue, we have successfully developed and characterized a prototypic borinic-based fluorescent probe containing a coumarin scaffold. We determined its in vitro kinetic constants toward H2O2-promoted oxidation. We measured 1.9 × 104m−1⋅s−1 as a second-order rate constant, which is 10,000-fold faster than its well-established boronic counterpart (1.8 m−1⋅s−1). This improved reactivity was also effective in a cellular context, rendering borinic acids an advantageous trigger for H2O2-mediated release of effectors such as fluorescent moieties.

Two Rival Newly Fabricated Potentiometric Sensors to Enhance Selectivity Toward Cu(II) Ions

Utilizing the well-known ability of Schiff base ligands to bind metal ions, two newly fabricated ligands, namely: 2-((2-hydroxybenzylidene)amino)benzoic acid (L1) and 2-(furan-2-ylmethyleneamino)phenol (L2) were employed to coordinate copper(II) (Cu(II)) producing the characteristically stable complexes that performed as the ionophores in the presently fabricated electrodes A and B. Thus it was possible to build these electrodes that have attractive properties and expected behavior, namely, low detection limits: 2.32 × 10–7 and 1.14 × 10–6 M Cu(II), Nernstian slope of 29.13 and 30.85 mV/decade Cu(II), broad concentration ranges from 3.98 × 10–7–1.00 × 10–2 and 1.52 × 10–6–1.00 × 10–2 M for sensors A and B, respectively, as well as short response time (ca. 3–5 s) with distinct selectivity toward Cu(II) over the other cations and applicability over the pH range 1.5–5.5 for miscellaneous samples: aqueous solutions, urine, and blood serum. Thus, these sensors surpass many others towards fulfilling the intended function of Cu(II) determination in various applications.

A Review of Off–On Fluorescent Nanoprobes: Mechanisms, Properties, and Applications

With the development of nanomaterials, fluorescent nanoprobes have attracted enormous attention in the fields of chemical sensing, optical materials, and biological detection. In this paper, the advantages of “off–on” fluorescent nanoprobes in disease detection, such as high sensitivity and short response time, are attentively highlighted. The characteristics, sensing mechanisms, and classifications of disease-related target substances, along with applications of these nanoprobes in cancer diagnosis and therapy are summarized systematically. In addition, the prospects of “off–on” fluorescent nanoprobe in disease detection are predicted. In this review, we presented information from all the papers published in the last 5 years discussing “off–on” fluorescent nanoprobes. This review was written in the hopes of being useful to researchers who are interested in further developing fluorescent nanoprobes. The characteristics of these nanoprobes are explained systematically, and data references and supports for biological analysis, clinical drug improvement, and disease detection have been provided appropriately.

Optical Micro-Wire Flow-Velocity Sensor

This paper presents a short response time, all-silica, gas-flow-velocity sensor. The active section of the sensor consists of a 16 µm diameter, highly optically absorbing micro-wire, which is heated remotely by a 980 nm light source. The heated microwire forms a Fabry–Perot interferometer whose temperature is observed at standard telecom wavelengths (1550 nm). The short response time of the sensor allows for different interrogation approaches. Direct measurement of the sensor’s thermal time constant allowed for flow-velocity measurements independent of the absolute heating power delivered to the sensor. This measurement approach also resulted in a simple and cost-efficient interrogation system, which utilized only a few telecom components. The sensor’s short response time, furthermore, allowed for dynamic flow sensing (including turbulence detection). The sensor’s bandwidth was measured experimentally and proved to be in the range of around 22 Hz at low flow velocities. Using time constant measurement, we achieved a flow-velocity resolution up to 0.006 m/s at lower flow velocities, while the resolution in the constant power configuration was better than 0.003 m/s at low flow velocities. The sensing system is constructed around standard telecommunication optoelectronic components, and thus suitable for a wide range of applications.

Method of improving performance of the low-inductance PMSM drive system

The disc coreless permanent magnet synchronous machine (PMSM) has a special coreless structure. This kind of PMSM has very low inductance, which is referred to as the low-inductance PMSM(LIPMSM) in this paper. The LIPMSM offers many advantages to drive systems. However, the current fluctuates strongly when driven by general converters, which makes the LIPMSM difficult to be popularized into modern drive systems. To tackle the above problems, a converter with output inductance is used. The influences of the inductance on the performance of the LIPMSM system are analysed, including current fluctuations, the maximum speed without flux weakening and the current response time. Based on above analyses, a method of obtaining the optimal inductance is proposed to obtain the optimal inductance simply and efficiently. The method has been verified through simulations and experiments. The system cannot work due to the huge current fluctuations when driven by the general converter. By using the converter with the optimal inductance, the current fluctuations have been reduced to 2 A. The experimental LIPMSM can reach 11000 rpm with very short response time of the current. Therefore, the LIPMSM system performance can been improved significantly and meet the requirements by using the converter with the optimal inductance.

The Hydrazone Organic Optical Modulator with π Electronic System for Ultrafast Photonics

The hydrazone organic compounds with strong conjugation effect have superior characteristics such as high nonlinear optical sensitivity, short response time, unique electronic spectrum and photothermal stability. The conjugated structure of...

2D Ferroelectric Devices: Working Principles and Research Progresses

Two-dimensional (2D) ferroelectric materials are promising to be used for high-performance nanoelectronic devices, due to the non-volatility, high storage density, low energy cost and short response time originated from the...

Monitoreo y control remoto de un dispensador de alimento para mascotas basado en IoT

The search for alternatives that facilitate the care and feeding of a pet has created the need to apply current technological development in this type of application, since pet owners have restricted time to stay with them due to their daily duties, studies, work or carelessness. In the region, acquiring an automatic device that dispenses food and water in the same equipment and includes remote monitoring through an app on a smartphone is challenging and can be expensive. Therefore, this work presents the development of an automatic device based on MQTT (Message Queuing Telemetry Transport) to dispense food and water for pets, capable of being monitored and controlled through a mobile device. By integrating multiple technologies and tools such as: programming languages, sensor and actuator management, Raspberry Pi, Arduino, CAD (Computer-Aided Design) design and 3D printing, this IoT (Internet of Things) solution allows to implement an innovative prototype that contributes to improve this social problem not only in our country but throughout the region. The functionality tests validate that the developed device has a short response time and that it allows pet owners greater independence and peace of mind.

Reversible photochromic properties of 4,5,6-triaryl-4H-pyran derivatives in a solid state

4,5,6-Triaryl-4H-pyran derivatives were reported to exhibit reversible solid-state photochromic phenomena with high-contrast, short response time, and excellent fatigue resistance upon UV-light and white-light irradiations.

Ultrasensitive Ti3C2TX MXene/Chitosan Nanocomposite-Based Amperometric Biosensor for Detection of Potential Prostate Cancer Marker in Urine Samples

Two-dimensional layered nanomaterial Ti3C2TX (a member of the MXene family) was used to immobilise enzyme sarcosine oxidase to fabricate a nanostructured biosensor. The device was applied for detection of sarcosine, a potential prostate cancer biomarker, in urine for the first time. The morphology and structures of MXene have been characterised by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Electrochemical measurements, SEM and AFM analysis revealed that MXene interfaced with chitosan is an excellent support for enzyme immobilisation to fabricate a sensitive biosensor exhibiting a low detection limit of 18 nM and a linear range up to 7.8 µM. The proposed biosensing method also provides a short response time of 2 s and high recovery index of 102.6% for detection of sarcosine spiked into urine sample in a clinically relevant range.