Fast Response Rate Research Articles

Comparative study on the thermal characteristics under different air distribution strategies oriented to non-uniform environment: An indoor experiment

With the epidemic becoming normal and realizing carbon neutrality goals, many scholars are focusing on finding reasonable air distribution strategies to provide a healthy indoor environment effectively. Hence, this study conducted a comparative experiment on the thermal characteristics under different air distribution strategies, namely interactive cascade ventilation (ICV), displacement ventilation (DV), stratum ventilation (SV), and underfloor air distribution (UFAD). Visualized and objective experiments were introduced to investigate the airflow characteristic, energy consumption and thermal comfort. The research results demonstrate that while maintaining the same supply air volume, ICV has the fastest response rate with the shortest spread-over time. Due to the dependence on the thermal buoyancy of DV, its delivery time is up to 134s. With the visualization experiment going on for 60 s, the effective outdoor air of ICV is 25.6% and 26.6% higher than SV and UFAD, respectively. In terms of energy consumption, compared to SV and UFAD, ICV enhances temperature drop per unit cooling capacity (TDCC) by 28.5% and 36.8%, showing the most significant local control ability, which is of great significance for epidemic prevention and control as well. Although the local coefficient of cooling capacity utilization (LCU) under ICV is similar to that under DV, the ICV can reduce the sizeable vertical temperature gradients under DV and improve the temperature uniformity of the occupied zone by 77.5%. The conclusions obtained from this study can efficiently provide new insights for building a healthy indoor environment with the epidemic normalizing.

Thiophene derived sky-blue fluorescent probe for the selective recognition of mercuric ion through CHEQ mechanism and application in real time samples

A vibrant blue organic luminescent material with enhanced photophysical properties is in great demand for the generation of optoelectronic devices and luminescent sensors. In this context, the thiophene-benzimidazole probe TH-IMI was designed and synthesized by a simple condensation reaction. The synthesized probe has shown excellent photophysical properties like high FL intensity, a high quantum yield of 90% in the solution phase, a low optical bandgap of 2.84 eV, positive solvatochromic effect in emission spectra and Disaggregation Caused Quenching Effect (DCQE). Such a high luminescent probe was employed for the recognition of mercuric ions in the solution phase, solid state detection, and in tracking mercury in green gram sprouts. UV–visible absorption and emission spectra, 1H NMR titration, IR spectroscopic and ESI-MS techniques confirmed that the probe underwent a fluorescence quenching response via the CHEQ effect upon exposure to Hg2+. The stoichiometry was found to be 1:1 through Job’s plot and has a fast response rate and relatively low limit of detection of about 6.13 × 10-11 M in a linear range between 0 and 110 µL.

Photoelectric performance of InSe vdW semi-floating gate p–n junction transistor

Semi-floating gate transistors based on vdW materials are often used in memory and programmable logic applications. In this paper, we propose a semi-floating gate photoelectric p–n junction transistor structure which is stacked by InSe/h-BN/Gr. By modulating gate voltage, InSe can be presented as N-type and P-type respectively on different substrates, and then combined into p–n junction. Moreover, InSe/h-BN/Gr device can be switched freely between N-type resistance and p–n junction. The resistance value of InSe resistor and the photoelectric properties of the p–n junction are also sensitively modulated by laser. Under dark conditions, the rectification ratio of p–n junction can be as high as 107. After laser modulation, the device has a response up to 1.154 × 104 A W−1, a detection rate up to 5.238 × 1012 Jones, an external quantum efficiency of 5.435 × 106%, and a noise equivalent power as low as 1.262 × 10−16 W/Hz1/2. It lays a foundation for the development of high sensitivity and fast response rate tunable photoelectric p–n junction transistor.

Pyrene‐based Fluorescent Probe for Rapid and Sensitive Detection of 2,4,6‐Trinitrophenol

AbstractTo rapid and efficient detection of TNP in water (TNP=2,4,6‐trinitrophenol), a pyrenyl‐based double‐charged probe PYPN was employed. The bright orange‐red emission of PYPN was seriously quenched upon the addition of TNP. The detection limit of PYPN for TNP is 0.218 μM. In addition, PYPN shows fast response rate (5 s) to TNP, good stability, excellent selectivity and anti‐interference (pH, anion, cation and other nitro compounds). Furthermore, PYPN can be used to rapidly detect TNP in various types of water samples. The rapid and efficient detection of TNP by PYPN may due to the electron and energy transfer as well as electrostatic interactions.

3D Printing Assisted‐Fabrication of Low‐Temperature Strain Sensors with Large Working Range and Outstanding Stability

Recently, low‐temperature wearable strain sensors, referring to those working at sub‐zero temperatures, are attracting increasing attentions. However, the fabrication of low‐temperature strain sensors with large working ranges, high sensitivity, and good stability remains a major challenge. In this study, a novel low‐temperature wearable strain sensor is fabricated by depositing the silver nanoplates (Ag NPs)/carbon nanotubes (CNTs) composite onto a cured silicone (DS) substrate that is constructed by using a 3D printing technology. The synergistic effect of the Ag NPs with positive temperature coefficient of resistance (TCR) and the CNTs with negative TCR enable the Ag NPs/CNTs/DS strain sensor's TCR value (−1.16 × 10−5 K−1) to approach zero. The Ag NPs/CNTs/DS strain sensor demonstrates a high gauge factor over a large working range (0–100%) and fast response and recovery rates. Simultaneously, the Ag NPs/CNTs/DS strain sensor displays outstanding reproducibility and long‐term stability at −40 °C as well as excellent temperature cycling resistance under cyclic temperature of −40 to 60 °C. The Ag NPs/CNTs/DS strain sensor is further validated by incorporating into a wireless sensing system for remotely monitoring various human activities at −40 °C. This work provides wearable strain sensors for monitoring human‐machine interaction under low‐temperature condition.

Anti-counterfeiting and Optical storage applications based on reversible modulated Down-shift Luminescence in photocoloration of MoO3: Eu3+ phosphor

Reversible and repeatable control of rare earth ions doped down-shift luminescence materials induced by the external field stimulation can be applied more widely. However, there is still a challenge on reversible luminescence regulation of photochromism-induced rare earth ions doped down-shift luminescence materials by light fields stimulation. The MoO3: Eu3+ phosphors changed color from light green to blue due to the formation of color centers caused by the trapping of electrons by oxygen vacancy defects under near infrared irradiation at 808 nm, and recovered from blue to initial light green after heating at 500 °C, showing a reversible change in color. The down-shift luminescence intensity of MoO3: Eu3+ phosphors reaches the maximum quenching degree, about 87%, after 20 s irradiation by 808 nm laser, which has the characteristics of fast response and great regulation rate. Moreover, the down-shift luminescence intensity can recover to the initial intensity after heating at 500 °C for 90 s, indicating reversible regulation of photochromism-induced down-shift luminescence. The application of MoO3: Eu3+ phosphors as the anti-counterfeiting labels and information storage of binary encoding was designed, these results suggest that it have certain potential applications in anti-counterfeiting and optical storage field.

Construction of a ratiometric fluorescent probe for discriminative detection of SO2 derivatives and Cys and its bio-imaging application

Endogenous sulfur dioxide (SO2) and cysteine (Cys) are important species and interacted with each other. However, due to the reactivity of these species, it is difficult to differentiated detection them. Thus, it is necessary to develop new fluorescent probe for discriminative detect these reactive sulfur species in biological environment. Herein, A new hemicyanine derivative Mito-AE with dual recognition sites for SO2 derivatives and Cys detection was constructed and applied in biological detection. Mito-AE exhibited ratiometric fluorescence change (F470/F610) of over 90-fold when interacted with SO2, and a dramatic fluorescence turn-on at 610 nm when interacted with Cys. The probe can monitor both SO2 derivatives and Cys with fast response rate (within 1 min), high sensitivity and selectivity. As proved by biological experiments, Mito-AE was able to successfully detect exogenous and endogenous SO2 in living cells as well as in mitochondria area. More importantly, the detection of SO2 derivatives and Cys in zebrafish model suggesting a potential application for studying the multiple interaction of biological sulfurous species in live organism.

Experimental and computational investigation on synergistic enhancement spray cooling using micropillars and capillary-driven wicking hybrid structures

Spray cooling, which has a fast thermal response and low flow rate consumption, is a common and effective thermal management approach for high power electronic systems. Typically, to improve the heat transfer coefficient (HTC) for spray cooling, the target surface wettability is decreased, promoting nucleation boiling by reducing the surface energy barrier for bubble nucleation. However, the merging of bubbles and the formation of a vapor film have limitations in further increasing the critical heat flux (CHF). Hence, maximizing both the HTC and CHF of spray cooling can be mutually exclusive on the same heated surface. This paper presented a novel design for a vapor-liquid separation structure surface. It consisted of lower micropillars that serve as the vapor separation channel. On top of that, there was an upper multi-layer copper micromesh that wicks and spreads the coolant. Additionally, nano-grass attached to the micromesh to enhance capillary force and increase the nucleation sites simultaneously. Subsequently, we calculated the forward velocity and pressure drop of the droplets passing through the copper mesh to study the effects of droplet velocity and capillary force on heat transfer performance. The results show that the forward velocity of the droplets decreases rapidly as the increase of copper mesh layers and it drops to zero when passing through the third mesh. Therefore, the capillary force generated by the copper mesh is another important factor for the atomized droplets to pass through the copper mesh and reach the target surface. We have proven that all the vapor-liquid separation structure surfaces satisfy the condition ΔPcap>ΔPpore+ΔPlocal. Hence, the synergistic effects of the micropillar, copper micromesh, and nano-grass enable a circulation process of wicking-rewetting-vapor evacuation, which improves the onset of nucleate boiling (ONB), enhances the HTC, and increases the maximum heat flux dissipated by the system. Enhanced HTC (7.94 W/cm2/K) and maximum heat flux (817 W/cm2) were achieved at 1.50 ml/s on the vapor-liquid separation structure surfaces (#200 2-layer), representing an enhancement of 79.6% and 80.0% compared with that for the flat surface and the temperature of the heated surface at the ONB maximum decreased by approximately 30.8 °C.

Magnetoactive microlattice metamaterials with highly tunable stiffness and fast response rate

Active metamaterials with shapes or mechanical properties that can be controlled remotely are promising candidates for soft robots, flexible electronics, and medical applications. However, current active metamaterials often have long response times and short ranges of linear working strains. Here, we demonstrate magnetoactive microlattice metamaterials constructed from 3D-printed, ultra-flexible polymer shells filled with magnetorheological (MR) fluid. Under compressive stress, the magnetorheological fluid develops hydrostatic pressure, allowing for a linear compression strain of more than 30% without buckling. We further show that under a relatively low magnetic field strength (approximately 60 mT), the microlattices can become approximately 200% stiffer than those in a relaxed state, and the energy absorption increases ~16 times. Furthermore, our microlattices showed an ultra-low response time with “field on” and “field off” times of ~200 ms and ~50 ms, respectively. The ability to continuously tune the mechanical properties of these materials in real time make it possible to modulate stress‒strain behavior on demand. Our study provides a new route toward large-scale, highly tunable, and remotely controllable metamaterials with potential applications in wearable exoskeletons, tactile sensors, and medical supports.

Use of QUIC for CoAP transport in IoT networks

The QUIC protocol, formerly known as Quick UDP Internet Connection, has recently been standardized by the Internet Engineering Task Force (IETF). While initially designed to support the transport of Hypertext Transfer Protocol version 3 (HTTP/3) messages, QUIC can also be employed for various applications. This paper explores the effective utilization of the QUIC protocol for transporting Internet of Things (IoT) messages. Specifically, we propose a proxy-based scheme that leverages the multi-streaming features of QUIC to deliver Constrained Application Protocol (CoAP) messages. In the proposed scheme, multiple CoAP connections between IoT clients and a server are aggregated using client proxy and server proxy. Each CoAP connection is mapped onto a designated QUIC stream. It is noted that this proxy-based approach can be implemented without requiring modifications to existing CoAP applications at the client and server sides. Furthermore, we introduce a compressed mapping scheme from CoAP messages to QUIC streams to enhance performance within the proxy-based model. In testbed experimentation, the proposed QUIC-based CoAP transport scheme is compared with the existing UDP-based and TCP-based CoAP schemes in a variety of IoT network environment. From the experimentation results, we see that the proposed QUIC-based scheme can achieve 80% reduction in round-trip time and 9% increase in fast response rate, compared to the other candidate schemes. We can also see that the CoAP over QUIC scheme with compression provides a 10% performance gain over the case without compression.

Development of epistatic YES and AND protein logic gates and their assembly into signalling cascades.

The construction and assembly of artificial allosteric protein switches into information and energy processing networks connected to both biological and non-biological systems is a central goal of synthetic biology and bionanotechnology. However, designing protein switches with the desired input, output and performance parameters is challenging. Here we use a range of reporter proteins to demonstrate that their chimeras with duplicated receptor domains produce YES gate protein switches with large (up to 9,000-fold) dynamic ranges and fast (minutes) response rates. In such switches, the epistatic interactions between largely independent synthetic allosteric sites result in an OFF state with minimal background noise. We used YES gate protein switches based on β-lactamase to develop quantitative biosensors of therapeutic drugs and protein biomarkers. Furthermore, we demonstrated the reconfiguration of YES gate switches into AND gate switches controlled by two different inputs, and their assembly into signalling networks regulated at multiple nodes.

Photochromic composites with fast light response, high contrast, and waterproof properties

Preparation of reusable photochromic materials is an effective strategy to alleviate resource waste, energy crisis and environmental problems. However, some weak links (such as slow light response rate, poor cycling stability, hydrophilicity, etc.) may limit their application in specific fields. Here, an intelligent material combines the advantages of inorganic compounds and organic substances, of which rapid charge transfer enables reversible color change assembly among semiconductors, polyoxometalates (POMs) and polymers. Specifically, Keggin-structure POMs are spontaneously attached to nitrogen-containing polymer by hydrogen bonds between terminal oxygen atoms of POMs and protons of amide nitrogen. Additionally, nano-TiO2 which acts as an extra electro donor is doped in this system. When exposed to UV light, the accelerated photoelectron transmission within the system achieves rapid color switching for a few seconds and achieves a reflection value difference of 64.12% within 60 s, displaying fast light response rate and high contrast. In addition, it also has stable cycling characteristics, with only a slight decrease in contrast after 20 times optical printing. On the premise of ensuring readability, a simple spraying treatment forms an anchorage of polydimethylsiloxane/TiO2 layer to photochromic layer, providing this material with waterproof properties. Encouragingly, this system can be applied by air-jet electrospinning, leading to a forward leap of self-fading time for compressing to 1 h. Overall, a waterproof photochromic composite has been developed based on the pain points of this material required overcoming, exhibiting potential in the fields of rewritable materials, anti-counterfeiting materials, indicator materials, etc.

Effect of Different Ratios of Red and Blue Light on Maximum Stomatal Conductance and Response Rate of Cucumber Seedling Leaves

Light can regulate leaf stomatal development and movement, but the effects of different red-to-blue light mass ratios on leaf stomatal morphology and openness are not fully understood. In this trial, five different red-to-blue light (R:B) ratio treatments were used to study the changes in morphology, photosynthesis, and stomatal-related indexes of cucumber seedlings under fixed light intensity (200 μmol·m−2·s−1). The results showed that the thickness of spongy tissue and stomatal size (SZ) of cucumber seedling leaves decreased, and the photosynthetic potential, stomatal density (SD), maximum stomatal conductance and stomatal responsiveness increased with decreasing R:B content. The experimental results showed that when R:B = is 1:9, cucumber seedlings had the greatest stomatal density and the fastest response rate, and the stomatal opening rate was accelerated with the increase in the proportion of blue light; when R:B = is 3:7, the stomatal conductance was the greatest and the net photosynthetic rate was the highest. This trial provides some implications for changing plant light quality and thus affecting stomatal development and movement.

Study on novel biphenyl chalcone scaffolds: A dual spectroscopic approach for efficient sensing of hydrazine with low concentration

Hydrazine and its derivatives, as harmful substances, seriously risk the health of humans and the environment. On the basis of the admirable luminescent properties and low biological harmfulness of the biphenyl moiety, a biphenyl moiety can be combined with a naphthalene ring via the chalcone scaffold easily traced by a nucleophilic group. Therefore, biphenyl chalcones (BPCs) decorated with various naphthalene systems as fluorescent sensors for hydrazine are synthesised by Claisen-Schmidt condensation. The present work describes the comparative studies of two different protocols for the synthesis of three different BPCs. The structures of all novel BPCs were investigated by FT-IR, NMR, and HRMS spectroscopy. These BPCs show a red shift with a fluorescent peak and an enhancement in intensity with increasing solvent polarity from hexane to methanol. Methanol shows strong fluorescence emission; therefore, methanol is used as the solvent in hydrazine sensing experiments. The BPCs display fluorescent variation from yellow to blue fluorescence after binding with hydrazine. These BPCs sensors are able to identify hydrazine in a fast response rate and 5 min response time. The screening study of hydrazine in various soil samples by prepared BPCs is highly efficient. A study of the pH dependence of these probes shows excellent sensitivity in the pH range of 5 to 10.

Ultrafast and High Extinction Ratio 1×4 Electro-Optical Switch Based on Cascaded Dual-Output MZI

We propose and fabricate an ultrafast and high extinction ratio 1×4 optical switch based on a cascade, dual-output Mach–Zehnder interferometer (MZI) on the lithium niobate platform. The optical switch consists of cascaded, identical, dual-output MZI structures, and each of them includes a Y-branch waveguide, two parallel interference arms (electrode action area), and a 3 dB directional coupler. Four output optical paths can be switched through three groups of electrode hierarchical modulation. The test results of the fabricated device show that the insertion loss of each port is less than 7.1 dB and that the maximum extinction ratio is higher than 39.3 dB. The optical switch can achieve a high extinction ratio greater than 20 dB within the 50 nm wavelength range. The measured half-wave voltage is less than 4.13 V, and the minimum switching rise and fall times reach 125 ps and 250 ps, respectively. This result shows that the proposed and fabricated 1×4 integrated optical switch on a lithium niobate platform has the advantages of a fast response rate, high extinction ratio, and low switching voltage.

Quaternary AgInP2S6: A Prospective Robust van der Waals Semiconductor for High‐Speed Photodetectors and their Application in High‐Temperature‐Proof Optical Communications

AbstractThe emergence of graphene has opened the prelude of extensive research on 2D layered materials. Especially, the diverse crystal structures and exceptional physical properties of multielement van der Waals semiconductors have provided a brand‐new platform for the implementation of novel optoelectronic devices. In this study, for the first time, the optoelectronic properties of a newly emerged quaternary van der Waals semiconductor, namely silver indium phosphorus sulfide (AgInP2S6), have been systematically investigated. It is revealed that the AgInP2S6 photodetector exhibits a fast response rate with the response/recovery time down to ≈1/2 ms. In addition, the AgInP2S6 device demonstrates stable photoswitching operation even under a high working temperature of up to 160 °C in the ambient environment without using any specific protection means, and the photoswitching characteristic is also well reserved after a 10‐h continuous heating at 150 °C in air. Profiting from the strong immunity to environmental thermal disturbance, a proof‐of‐concept high‐temperature optical communication application is demonstrated. In conclusion, this study provides an intriguing paradigm for the realization of the next‐generation optoelectronic devices against extreme working circumstances, which contributes to further broadening the scope of application of 2D material photodetectors in the upcoming future (e.g., space communication and tracking).

Low-power, fast response simplified electrochromic device based on functionalized gel electrolyte

Metallo-supramolecular polymer (MEPE)-based thin film electrochromic devices (ECDs) have been considered to be a promising platform for portable electronics as their low cost, excellent redox properties, high optical contrast, and rich colors. However, poor cycle stability and slow response speed are serious bottlenecks for widespread commercial devices. Here, a gel electrolyte functionalized by the anodic active species p-benzoquinone (p-BQ) (GET-BQ) was reported. It has outstanding conductivity (∼4.62 mS cm−1) and transparency. Fe(Ⅱ)-MEPE-based ECDs incorporating the GET-BQ electrolyte (ECD-BQ) showed lower voltage operation (∼1.1 V), higher optical contrast (ca. ΔT ∼ 35.7%), faster response rate (tb ∼ 2.5 s, tc ∼ 0.3 s), and superb cycling durability (<1.7% ΔT loss after 1440 cycles) than those without p-BQ. Moreover, the charge transport kinetics of ECD-BQ were explored by the CV curve, in situ infrared spectroelectrochemical analysis, and electrochemical impedance spectroscopy. The charge transfer mechanism of electrochromic material and electrolytes in ECD-BQ offers a novel entry to design superior electrolytes for high-performance ECD.

Magnetic Bucket Brigade Transport Networks for Cell Transport

AbstractControlled transport of biological cells in biomedical applications such as sorting, cell sequencing, and assembly of multicellular structures is a technological challenge. Research areas such as drug delivery or tissue engineering can benefit from precise cell location resulting in faster response rates or more complex tissue structures. Using computational methods, different soft magnetic elements with curved edges are designed to form a transport network, enabling transport and all functionalities for the manipulation of microbeads and cells on surfaces by rotational magnetic fields. Building blocks with bimodal functionalities due to segments of differently curved edges permit breakpoints as well as switchable transport via splitting and combining elements. Connecting the elements, networked paths are realized which allow variable movement patterns of magnetic carriers and cells. The direction of magnetic field rotation is altered to direct the beads and cells into different transport lines, and the exact timing is not critical. The networks are used to achieve deterministic movement of microbeads and cells with minimal intervention. Programmed transport over one millimeter with cell transport velocities of several micrometers per s is demonstrated. Based on scalable microchip technology, the networks can be integrated with CMOS‐compatible materials and straightforwardly combined with sensing and diagnostic structures.

Facile Fabrication of Oxygen‐Enriched MXene‐Based Sensor and Their Ammonia Gas‐Sensing Enhancement

AbstractVarious sensing materials have been demonstrated to increase the precision of sensing technology. Nevertheless, this complicates the fabrication process for materials integration to obtain devices that can simultaneously accommodate various gas detectors, like electronic nose. The study here focuses on exploring the sensing response of different functionalization of specific sensing materials to provide an alternative way to achieve selective response to multiple gases. Triethoxysilylpropyl succinic anhydride silane (TESPSA) was introduced on 2D material MXene‐Ti3C2Tx to form carboxylic acid terminated MXene (COOH‐Ti3C2Tx) and alternately coated with polyaniline (COOH‐Ti3C2Tx/PANI). This modification doubled up the gas binding sites and improved the binding strength of the Ti3C2Tx surface to NH3 gas molecules. The 5CC‐COOH‐Ti3C2Tx/PANI sensor prepared from five coating cycles showed the highest sensitivity (214.70 %) with fast gas response rate at 80 ppm NH3 (1.75 % s‐1). Therefore, the different signal responses from specific functionalization of the same sensing material functionalization will allow the possible sensor array fabrication to achieve fingerprint‐like sensing map recognition in the presence of mixed gases.

Hemin as a General Static Dark Quencher for Constructing Heme Oxygenase‐1 Fluorescent Probes

AbstractThe development of small‐molecule probes suitable for live‐cell applications remains challenging yet highly desirable. We report the first fluorescent probe, RBH, for imaging the heme oxygenase‐1 (HO‐1) activity in live cells after discovering hemin as a universal dark quencher. Hemin works via a static quenching mechanism and shows high quenching efficiency (&gt;97 %) with fluorophores across a broad spectrum (λex=400–700 nm). The favorable properties of RBH (e.g. long excitation/emission wavelengths, fast response rate and high magnitude of signal increase) enable its use for determining HO‐1 activity in complex biological samples. As HO‐1 is involved in regulating antioxidant defence, iron homeostasis and gasotransmitter carbon monoxide production, we expect RBH to be a powerful tool for dissecting its functions. Also, the discovery of hemin as a general static dark quencher provides a straightforward strategy for constructing novel fluorescent probes for diverse biological species.