Broad Working Research Articles

Visual monitoring of hydrazine in food and environmental samples by wearable probe

Hydrazine is a poisonous compound that has been widely applied in the agricultural and chemical industry, leading to serious environmental pollution. Thus, the detection of hydrazine remained extremely important for ensuring food safety and environmental protection. Considering the importance of hydrazine detection for human health, a novel colorimetric/fluorescent probe (TPB) for the detection of hydrazine in various samples has been developed. In the presence of hydrazine, TPB emits a blue emission band at 452nm with high sensitivity (limit of detection equal to 40nM), ultrafast detection (less than 10s), broad working pH range (6−10), and strong anti-interference capabilities. These excellent performances have been exploited to fabricate hydrogel-based sensing labels (test kits, cotton swabs, glass rods, and gloves), which allowed the detection of hydrazine traces in soil, earthworms, plant samples, and living cells. This work presents a novel sensing approach for future research, aiming to develop a novel fluorescent probe exploiting the ICT process for the detection of hydrazine.

Boosting Low-E electro-strain via high-electronegativity B-site substitution in lead-free K0.5Na0.5NbO3-based ceramics

Lead-free piezoelectric actuators emerge as promising substitutes for their lead-containing counterparts to address environmental concerns. However, they often confront a trade-off between low driving electric fields and high electro-strain. Herein, a novel strategy to boost electro-strain under low electric fields is proposed by doping high-electronegativity B-site atoms into perovskite potassium sodium niobate-based ceramics. Our findings reveal that high-electronegativity B-site atoms elevate the covalency of B-O bonding, softening the short-range repulsion and introducing local multiphase coexistence. This leads to more nanoscale domain structures and lower coercive field, thereby enabling large strains to be produced at lower electric fields. Notably, a substantial 0.2 % bipolar electro-strain and 0.1 % unipolar electro-strain under 10 kV cm-1 is achieved in Sr, Sb co-doped potassium sodium niobate ceramics, with a broad working frequency and temperature range, as well as excellent fatigue resistance. This study unveils innovative insights into designing lead-free piezoelectric ceramics with remarkable electro-strain performance and low driving electric field, promising a significant advancement in lead-free piezoelectric materials science and piezoelectric actuators.

Ultrabroadband and >93% Microwave Absorption Enabled by "Doped" Water Meta-Atom Lattice with Subwavelength Thickness.

Perfect microwave absorbers, which absorb electromagnetic waves completely, play pivotal roles in electromagnetic shielding, and stealth technologies. Existing microwave absorber technologies rely on either electromagnetic properties of absorptive materials, the resonance behavior of meta-atoms, or a combination of both. So far, achieving simultaneous broadband absorption, high efficiency, and compact sizes remains a great challenge. Inspired by atomic doping techniques employed in conventional optical materials to broaden spectral bandwidths, a single-layer microfluidic metasurface microwave absorber is proposed with the assembly of two distinct types of water meta-atoms. By manipulating electromagnetic resonances of these water meta-atoms, the metasurface maintains impedance matching over a broad working range. A microwave absorber design with a thickness equivalent to 0.2 times the central wavelength is showcased, measuring over 93% absorption across both K and Ka bands (17.5-40.0GHz). The results highlight unprecedented superiorities of microwave absorbers based on a 2D doped water meta-atom lattice when compared to previously reported metasurface absorbers utilizing identical meta-atoms. This absorber has advantages including small thickness, broad bandwidth, and cost-effectiveness, making it promising for applications in electromagnetic shielding, camouflage, and multi-spectral stealth.

Photoelectrochemical Immunoassay of Alpha‐Fetoprotein Based on Au Nanoparticles‐Decorated ZnO Microrods

AbstractHerein a split‐type photoelectrochemical (PEC) immunosensor based on in situ grown gold nanoparticles (Au NPs) on the surface of ZnO microrods (ZnO MRs) was devised for the detection of alpha‐fetoprotein (AFP) by employing dopamine (DA)‐loaded liposomes as the signal amplification strategy. Specifically, as the level of AFP rises, a proportional number of sandwich‐type immunocomplexes form in the well of the microplate, which can introduce a corresponding amount of DA‐encapsulated liposomes at the same time. Encapsulated DA molecules will be released with the stimulation of Triton X‐100, thereby resulting in the marked enhancement of the PEC signal. Under optimized conditions, the proposed PEC immunosensing platform displays specific photocurrent responses toward AFP in a broad dynamic working range of 0.05 −50 ng mL−1, achieving an impressively low limit of detection (LOD) of 18.7 pg mL−1. Furthermore, this methodology not only displays high specificity, and satisfactory storage stability but also ensures acceptable accuracy and practicality for the analytical applications of human serum samples.

Improving the energy storage efficiency and power density of polymer blend in combination with Ti3C2Tx for energy storage devices

Polymer blend-based dielectrics are extensively used because of their broad working temperature range, quick discharging speed, and high power density. The solution casting approach is used to prepare the PVDF/PMMA- Ti3C2Tx nanocomposite flexible energy storage films. The morphology results show that the composite has a homogeneous and dense microstructure. The structural study shows the composition of thin films and confirms the existence of the PVDF β-phase. The thermal analysis showed 31.36 % crystallinity for 20 wt% of nanocomposite (NCs). The values of band gap energy reduced from 3.07 eV to 2.65 eV with increasing Ti3C2Tx concentration (15 wt%). It was found that the almost high dielectric constant values of (̴205) at 100 Hz and loss of 0.078 were suggestive of increased interfacial polarization. The maximal energy density of the NCs is 1.28 J/cm3, and its power density is 4.86 MW/cm3 for 15 wt% NCs. The conductivities of 15 wt% composite increase to 10−9 –10−7 S.cm−1 at 100 Hz, and then it reaches nearly 10−3 S cm−1 when the frequency is raised to 1 MHz. The 2D MXene nanofiller and PVDF macromolecular chain have an improved interface interaction, which results in excellent complete electrical characteristics. The rise in residual polarization can be inhibited by adding PMMA. In this work, adding 2D Ti3C2Tx MXene to PVDF/PMMA blends offers a viable way to create materials that are highly effective at storing energy in capacitors.

Design of super stretchability, rapid self-healing, and self-adhesion hydrogel based on starch for wearable strain sensors

Since hydrogels are conductive, easily engineered, and sufficiently flexible to imitate the mechanical properties of human skin, they are seen as potential options for wearable strain sensors. However, it is still a great challenge to prepare a hydrogel through simple and straightforward methods that integrate excellent stretchability, ionic conductivity, toughness, self-adhesion, and self-healing. Herein, an acrylamide/3-acrylamide phenylboronic acid cross-linked network is modified to produce a semi-interpenetrating cross-linked hydrogel in just one easy step by adding starch. The prepared hydrogel contains dynamic boronic ester bonds and hydrogen bonds, which endow the exceptional stretchability (5769–13,976 %, 20–50 wt%), ideal transmittance (>90 %), self-adhesiveness (0.636 ± 0.060 kPa, 30 wt%), and self-healing properties. Notably, the self-healing process is completed instantly, achieving a healing strength of up to 81.21 %. Additionally, the aforementioned hydrogel exhibits a broad working strain range (≈ 500 %) and high sensitivity (gauge factor = 1.99) as a strain sensor, allowing it to record and track human actions precisely. This work provides a novel approach to synthesizing hydrogels with optimal overall mechanical characteristics, with the potential to facilitate the development of wearable strain sensing system based on hydrogels for real-world applications.

Tunable Ag-Ox coordination for industrial-level carbon-negative CO2 electrolysis

The electrochemical CO2 reduction (eCO2RR) is promising for eliminating CO2, generate valuable chemicals and utilize spare electricity. However, its industrialization is greatly hindered by low CO2 single-pass conversion efficiency (SPCE) in alkaline/neutral electrolytes, and poor compatibility between the electrolysis and intermittent energy system. Herein, a carbon-negative acidic eCO2RR system is developed using acidic-tolerant Ag based metal-organic frameworks (Ag-MOFs), achieving a high Faradaic efficiency of CO above 97 % in a broad working window of 10–400 mA cm−2 for unsaturated Ag-O2 clusters, and a high CO2 SPCE of 46.3 % even under industrial-level 400 mA cm−2. Being connected to solar cells, the acidic eCO2RR system displays a remarkable solar-to-chemical efficiency of 19.74 %, offering great potential for industrial eCO2RR directly driven by renewable energy. Specifically, the CO/HCOOH selectivity could be manipulated by adjusting the coordination number of Ag atoms in Ag-MOFs, and thus a Pourbaix-diagram is proposed to explain the tunable selectivity theoretically.

Reversible Giant Barocaloric Effect with Broad Working Temperature Range in an Amorphous Ethylene Propylene Diene Monomer.

The barocaloric effect of a solid material is an intense research topic due to its potential application in solid-state refrigeration. Among the proposed candidates, elastic polymers are distinctive because their barocaloric responses are independent from a pressure-induced phase transition which makes it possible to realize a broad working temperature range in principle. However, the barocaloric performance of most elastic polymers diminishes significantly as temperature decreases. In this work, giant and reversible barocaloric effects were observed in a broad working temperature range from 252 to 345 K in an amorphous polymer of ethylene propylene diene monomer, which are much higher than the investigated crystalline and partially crystallized ones. It is demonstrated that the degree of crystallinity can be a key factor responsible for the mobility of polymer chains and the corresponding barocaloric performance at low temperatures. The reversible giant barocaloric effects, broad working temperature regions, low cost, and absence of pressure-transmitting fluid make the ethylene propylene diene monomer attractive for solid-state barocaloric refrigeration.

A Double-Layer Polyurethane Electrospun Membrane with Directional Sweat Transport Ability for Use as a Soft Strain Sensor.

Wearable electronics for long-term monitoring of physiological signals should be capable of removing sweat generated during daily motion, which significantly impacts signal stability, human comfort, and safety of the electronics. In this study, we developed a double-layer polyurethane (PU) membrane with sweat-directional transport ability that can be applied for monitoring strain signals. The PU membrane was composed of a hydrophilic, conductive layer and a relatively hydrophobic layer. The double-layer PU composite membrane exhibited varied pore size and opposite hydrophilicity on its two sides, enabling the spontaneous pumping of sweat from the hydrophobic side to the hydrophilic side, i.e., the directional transport of sweat. The membrane can be used as a strain sensor to monitor motion strain over a broad working range of 0% to 250% with high sensitivity (GF = 4.11). The sensor can also detect simple human movements even under sweating conditions. We believe that the strategy demonstrated here will provide new insights into the design of next-generation strain sensors.

Preparation and sensing properties of multiscale conductive filler hybrid CNTs@Ag-MXene-TPU/TPU double-layer strain sensing materials

The performance of sensors is often limited by the structural characteristics of the single form of conductive filler, making it difficult for sensors to simultaneously consider the broad sensing range and high sensitivity. How to achieve high sensitivity and broad working range of sensors through innovative sensing materials and sensor structure design remains a challenge. Here, a flexible sensor with multidimensional sensing materials and a double-layer structure is constructed. It consists of a high-performance CNTs@Ag-MXene-TPU sensing layer and a TPU flexible layer with significant deformability. Thanks to the synergistic effect of the double-layer structure and multidimensional sensing materials, this sensor has a high sensitivity of up to maximum gauge factor of 12216.3 and a wide sensing range of 300 %. Its response time and recovery time can reach 200 and 250 ms, respectively, and it also exhibits excellent cycling stability.

A lysosome-located and rhodamine-based fluorescence probe for recognizing hydrogen polysulfide

Hydrogen polysulfide (H2Sn, n≥2), as a kind of active sulfur species (RSS), has become a hot topic in RSS. It can regulate the biological activity of many proteins through S-sulfhydrylation of cysteine residues (protein Cys-SSH), and has a protective effect on cells. Although there have been some studies on hydrogen polysulfide, its production, degradation pathway and regulation mechanism still need further be researched. In presented study, an original lysosome-localized fluorescent probe for determining H2Sn was developed utilizing rhodamine as the fluorogen. The probe used morpholine as the locating unit of lysosomes and chose 2-fluoro-5-nitrobenzoate as the recognizing group. Before adding H2Sn, the proposed probe displayed a spironolactone structure and emitted very weak fluorescence. After adding H2Sn, a conjugated xanthene was formed and the probe demonstrated green fluorescence. When the H2Sn concentration was varied from 6.0×10−7 mol·L−1 to 10.0×10−5 mol·L−1, the fluorescence intensity of the probe was linearly dependent on the H2Sn concentration. And the detection limit was 1.5×10−7 mol·L−1. The presented probe owned a fast response speed, good selectivity, excellent sensitivity and broad pH work scope. In addition, the probe had been well utilized to sense endogenic and exogenic H2Sn in lysosomes.

Lightweight and flexible polysulfonamide/polyurethane-CNTs@Ag fiber paper for electromagnetic interference shielding

Nowadays, electromagnetic wave radiation is one of the sources of environmental pollution, which seriously affects human health and and the environment. Fiber paper made from high-performance fibers has shown potential for use in the electromagnetic interference (EMI) shielding due to adapting different complex working environments. However, achieving lightweight, high-efficiency, and flexible electromagnetic shielding remains challenging. To address this issue, we design a lightweight polysulfonamide/polyurethane-CNTs@Ag (PSA/PU-CNTs@Ag) fiber paper with double-layered structure and high electromagnetic shielding efficiency (EMI SE) via vacuum-assisted filtration and heat treatment. The results show the content of Ag nanoparticles 0.3 g in PSA/PU-CNTs@Ag fiber paper, the resistance is less than 1 Ω, the electrical conductivity reaches 883.57 S/m. At the same time, the thickness of Ag film increases, the EMI SE value reaches 90.537 dB. The EMI SE value of PSA/PU-CNTs@Ag fiber paper after folding one thousand times has decreased, but still maintains 95% of the original shielding performance. Moreover, its EMI SE values still maintain above 60 dB in various extreme environments (hot 150 °C, cold −70 °C). In summary, this work shows PSA based EMI shielding materials own excellent overall performance and hold broad different working extreme environments.

Highly selective capture of Hg(II) utilizing a MXene-based magnetic cenosphere: Balance on redox sites and magnetism

Hg(II), as a hazardous water pollutant, is attracting increasing attention due to its severe ecological and biological toxicity. Herein, a magnetic composite MXene/Fe3O4/FAC for aqueous Hg(II) uptake was prepared. It appeared fast adsorption kinetics (∼30 min of adsorption equilibrium time), high Hg capacity (924.34 mg/g), broad working pH range (pH=4–12), and high selectivity. Besides, the implanted Fe3O4 empowered the composite with good recycling and reusing characteristics, effectively preventing the release of nanomaterials into the environment. Multiple adsorption models and characterizations revealed the Hg(II) adsorption behaviors and mechanisms and the impact of Fe3O4 on Hg(II) adsorption onto MXene. Specifically, Hg(II) reductive adsorption aroused by the low-valence Ti species (abbreviated as Ti*) is the foremost mode of MXene. With the increasing of Fe3O4 (especially trivalent Fe), Ti* tends to be oxidized and covered by Fe3O4, and less Ti* can be used for Hg(II) reductive adsorption, leading to slower adsorption kinetics and lower adsorption capacity. The introduced inert carrier FAC favors the good dispersion of Fe3O4 and MXene to alleviate the oxidation of MXene, achieving the high utilization of MXene materials. The new insight into the interaction between MXene and Fe3O4 can beneficially guide the synthesis of Hg(II) magnetic adsorbents and MXene-based functional materials.

Outstanding comprehensive energy storage performances in multiscale synergistic regulation-engineered (Bi0.5Na0.5)TiO3-based multilayer ceramics

Environmentally friendly dielectric ceramics with superior energy storage performances (ESP) are strongly demanded in pulsed power capacitor applications. Unfortunately, it is challenging to achieve simultaneously large recoverable energy density (Wrec), high Wrec/E (E as electric field) and broad operating temperature range in those ceramics. Herein we propose a multiscale synergistic regulation strategy to enhance comprehensive ESP of (Bi0.5Na0.5)TiO3 (BNT)-based ceramics. We introduce Ca(Zr0.8Ti0.2)O3 (CZT) into the BNT to increase atomic chaos and lattice distortion, which enhances relaxor behavior and lowers domain-switching barriers, thus effectively reducing remanent polarization. Besides, both suppressed oxygen vacancy and refined submicron grains improve extrinsic resistivity, which works synergistically with the enlarged intrinsic bandgap and multilayer structure design, producing substantially enhanced breakdown strength. Encouragingly, a very large Wrec of 13.4 J/cm3, an ultrahigh Wrec/E of 160 J/(kV∙m2), and a high efficiency η of 90.2 % are simultaneously achieved in the novel (Bi0.5Na0.5)TiO3-Ca(Zr0.8Ti0.2)O3 (BNT-CZT) multilayer ceramics, together with outstanding energy storage stability over a broad working temperature range (20–180 °C). The comprehensive ESP of our multilayer ceramics are superior to most of previously reported lead-free ones. This work provides a feasible pathway for substantially improving comprehensive ESP of lead-free ceramics, and also highlights advanced energy storage potential of the BNT-CZT for high-performance pulsed power applications.

Microsecond-Scale Transient Thermal Sensing Enabled by Flexible Mo1-xWxS2 Alloys.

Real-time thermal sensing through flexible temperature sensors in extreme environments is critically essential for precisely monitoring chemical reactions, propellant combustions, and metallurgy processes. However, despite their low response speed, most existing thermal sensors and related sensing materials will degrade or even lose their sensing performances at either high or low temperatures. Achieving a microsecond response time over an ultrawide temperature range remains challenging. Here, we design a flexible temperature sensor that employs ultrathin and consecutive Mo1-x W x S2 alloy films constructed via inkjet printing and a thermal annealing strategy. The sensing elements exhibit a broad work range (20 to 823 K on polyimide and 1,073 K on flexible mica) and a record-low response time (about 30 μs). These properties enable the sensors to detect instantaneous temperature variations induced by contact with liquid nitrogen, water droplets, and flames. Furthermore, a thermal sensing array offers the spatial mapping of arbitrary shapes, heat conduction, and cold traces even under bending deformation. This approach paves the way for designing unique sensitive materials and flexible sensors for transient sensing under harsh conditions.

Strong and Robust Core-Shell Ceramic Fibers Composed of Highly Compacted Nanoparticles for Multifunctional Electronic Skin.

Functional fibers composed of textiles are considered a promising platform for constructing electronic skin (e-skin). However, developing robust electronic fibers with integrated multiple functions remains a formidable task especially when a complex service environment is concerned. In this work, a continuous and controllable strategy is demonstrated to prepare e-skin-oriented ceramic fibers via coaxial wet spinning followed by cold isostatic pressing. The resulting core-shell structured fiber with tightly compacted Al-doped ZnO nanoparticles in the core and highly ordered aramid nanofibers in the shell exhibit excellent tensile strength (316MPa) with ultra-high elongation (33%). Benefiting from the susceptible contacts between conducting ceramic nanoparticles, the ceramic fiber shows both ultrahigh sensitivity (gauge factor = 2141) as a strain sensor and a broad working range up to 70 °C as a temperature sensor. Furthermore, the tunable core-shell structure of the fiber enables the optimization of impedance matching and attenuation of electromagnetic waves for the corresponding textile, resulting in a minimum reflection loss of -39.1dB and an effective absorption bandwidth covering the whole X-band. Therefore, the versatile core-shell ceramic fiber-derived textile can serve as a stealth e-skin for monitoring the motion and temperature of robots under harsh conditions.

A Fabric-Based Strain Sensor with a Microbridge Structure and the Supercapacitor-Powered Integrated Sensing System.

Developing fabric-based strain sensors with high sensitivity and stability is in high demand for wearable electronics. Herein, carbon nanotubes (CNTs) and polypyrrole (PPy) are coated on a thermoplastic polyurethane (TPU) fabric as strain sensors. A microbridge structure, in which CNT bridges the stretching-induced cracks, has been designed for the TPU-CNT-PPy strain sensor. The microbridge structure can significantly enhance the electrical resilience, ensuring the improved sensitivity and stability of strain sensors. As a result, our TPU-CNT-PPy strain sensors deliver high sensitivity (GF = 231.5) with a broad working range (150%) and fast response and recovery time (166/195 ms). In addition, our TPU-CNT-PPy could also be used as flexible electrodes of the microsupercapacitors (MSCs) as a power supplier for the integrated sensing system. The TPU-CNT-PPy-based MSCs exhibit a high specific capacitance (460.3 mF cm-2 at 0.5 mA cm-2) and excellent cycling stability (96.69% capacitance retention for 10,000 charge/discharge cycles). Finally, we demonstrated an integrated sensing system using TPU-CNT-PPy as both MSCs and strain sensors, where the current signals of the sensors could be well detected via Bluetooth. This study offers a microbridge strategy to fabricate strain sensors with high sensitivity and stability and develops an integrated sensing system for the actual applications of wearable electronics.

Biodegradable poly(lactic acid) blocked polyurethane/carbon nanotubes coated cotton fabric prepared by ultrasonic-assisted inkjet printing for high performance strain sensors

In order to fulfill the demands for degradability, a broad working range, and heightened sensitivity in flexible sensors, biodegradable polyurethane (BTPU) was synthesized and combined with CNTs to produce BTPU/CNTs coated cotton fabric using an ultrasonic-assisted inkjet printing process. The synthesized BTPU displayed a capacity for degradation in a phosphate buffered saline solution, resulting in a weight loss of 25 % after 12 weeks of degradation. The BTPU/CNTs coated cotton fabric sensor achieved an extensive strain sensing range of 0–137.5 %, characterized by high linearity and a notable sensitivity (gauge factor (GF) of 126.8). Notably, it demonstrated a low strain detection limit (1 %), rapid response (within 280 ms), and robust durability, enabling precise monitoring of both large and subtle human body movements such as finger, wrist, neck, and knee bending, as well as swallowing. Moreover, the BTPU/CNTs coated cotton fabric exhibited favorable biocompatibility with human epidermis, enabling potential applications as wearable skin-contact sensors. This work provides insight into the development of degradable and high sensing performance sensors suitable for applications in electronic skins and health monitoring devices.

Infrastructure, time and labour: movement and suspension along the Abidjan-Lagos corridor

ABSTRACT Africa’s renewed push towards infrastructure development brought with it new forms of territorialisation tied to both capital and labour. Infrastructures are expected to connect specific African hubs to global trade flows, promote industrialisation and increase employment rates, yet they often struggle to fulfil said promises. We explore the relationship between Africa’s ‘infrastructure turn’ and changing labour relations through the case of the Abidjan-Lagos Corridor in West Africa. Drawing from critical infrastructure studies and broader work in labour geography, we use the concept of suspension as a lens to illuminate a variety of processes – occurring across varied temporalities and scales – that are imbricated in the construction of different forms of infrastructural labour. We posit that infrastructure development as currently structured simultaneously (i) reinforces geopolitical inequities in the division of labour in the design and implementation of infrastructure projects; (ii) fosters competition amongst states for value and trade capture; and (iii) prompts contestation and disavowal in the context of the construction of specific projects. These three distinct, yet inter-related ways in which infrastructure development entangles with labour dynamics highlight that the work of imagining and crafting infrastructural promise creates pathways for novel, and often contested, configurations of labour relations.

Academic work demands and the primacy of English: an additional burden for non-native English speakers

ABSTRACT For some time, academics have reported the increasing complexity and demands of work (Clegg, S. 2008. “Academic Identities Under Threat?” British Educational Research Journal 34 (3): 329–345. https://doi.org/10.1080/01411920701532269), including the difficulty of gaining permanence (Taylor, A. 2018. Scientists Don’t Stay for Long in Their Jobs Anymore: Study. Accessed July 20, 2023. https://www.the-scientist.com/news-opinion/scientists-dont-stay-for-long-intheir-jobs-anymore--study-65200) and the constant expectation, even if permanent, to publish as first author in high-impact journals (usually English) – where success rates are dropping due to this high demand. Even as native-English speakers, these expectations can be challenging and stressful. However, for non-native speakers, there is an additional demand given the primacy of English: using English as their language of publication. Prior studies suggest two clusters of factors at play: structural (e.g. university publication requirements for permanence) and individual (e.g. career motivation) which interact. But, broader work and life experiences are rarely addressed. So, this study asked: Within the context of their broader lives, what structural and individual factors do 31 LAC researchers perceive and negotiate in making LoP decisions? Furthermore, how do combinations of these interacting factors lead to different LoP decisions? This broader lens offered many insights with implications for researching academic work (e.g. incorporating prior life and work linguistic experiences in LoP decision-making), and native English academics' publishing practices (e.g. as journal editors and reviewers structures).