Sandwich-like Configuration Research Articles

Development of two novel supramolecular metallogels of Mn(II) and Zn(II)-ion derived from L-(+) tartaric acid for fabricating light responsive junction type semiconducting diodes with non-ohmic conduction mechanism

Abstract A rapid development strategy was successfully implemented to create a suEPSR111459pramolecular metallogel comprising Mn(II) (referred to as MnA-TA) and Zn(II) (referred to as ZnA-TA) ions. These gels were formed using L-(+)-tartaric acid as a low molecular weight gelator in DMF medium at ambient conditions. Rheological analysis was employed to assess the mechanical stability of the synthesized MnA-TA and ZnA-TA metallogel. The results of the analysis revealed the gel’s impressive resilience when subjected to various angular frequencies and levels of oscillator stress. The exploration of MnA-TA and ZnA-TA metallogel’s distinct morphological patterns was conducted using FESEM images. FESEM analysis revealed that MnA-TA metallogel exhibited a flake-like hierarchical network structure, while ZnA-TA metallogel demonstrated a diamond-shaped architecture. EDX analysis was utilized for elemental mapping, confirming the presence of primary chemical constituents in the metallogels. The formation strategy and nature of the gel materials were examined through FT-IR spectroscopy and PXRD analysis. The synthesized metallogels exhibited semiconducting properties, as confirmed by optical band-gap measurements. Furthermore, a metal-semiconductor junction-based device was successfully fabricated by combining Al metal with Mn(II)- and Zn(II)-metallogels. The device displayed nonlinear charge transport behavior, resembling that of a Schottky diode, as evidenced by its I-V characteristic. This indicates the potential use of the sandwich-like configuration of ITO/MnA-TA metallogel/Al and ITO/ZnA-TA metallogel/Al in the development of advanced electronic devices based on supramolecular Mn(II)- and Zn(II)-metallogels. Notably, the direct utilization of tartaric acid and Mn(II)/Zn(II) sources in the MnA-TA and ZnA-TA metallogels presents an innovative approach, highlighting their suitability as semiconducting materials for device fabrication. This study delves into the multifunctional applications of MnA-TA and ZnA-TA metallogels, providing valuable insights for researchers in the field of material science. Graphical Abstract

Assessment of ply thickness and aluminum foils interleaving on the impact response of CFRP composites designed for cryogenic pressure vessels

Carbon fiber reinforced polymer (CFRP) proved to be the best choice to produce cryogenic pressure vessels coupling a reduced weight with superior mechanical performance. Despite this, CFRPs are prone to fuel leakage due to interconnected matrix cracks resulting from mechanical and thermal stresses. Two strategies were combined in this work to reduce fuel permeability, i.e., increase of plies number and metallic film interleaving, evaluating the cryogenic impact response of these new configurations. At first, the only ply thickness effect was assessed and the hybrid sandwich-like (SL) configuration with traditional CFRP (RC) skins and a thin-ply (TP) core displayed impact and residual flexural properties close to RC ones. Then, the effect of aluminum foils interleaving was investigated, and the interleaved SL configuration displayed higher residual flexural properties than interleaved RC for all temperatures, e.g., the residual flexural strength was 30.3 % higher at room temperature and 14.6 % higher at −70 °C, respectively.

The enhancement of intelligent electric response properties in the Polymer Gel Artificial Muscle (PGAM) by incorporating micro/nanoscaled doping and regulation of Graphene Oxide (GO)

To align with the principles of environmental conservation and sustainable progress, a Polymer Gel Artificial Muscle (PGAM) was designed with a sandwich-like configuration, comprising two non-metallic electrode membranes enclosing an electrically-actuated membrane. This PGAM exhibited promising prospects due to its advantageous features such as lightweight, intelligibility, flexibility, and excellent activity. However, despite the widespread utilization of polymer gels, their investigation into intelligent electric response property remained a significant challenge. This study investigated the intelligent electric response properties of the enhanced PGAM by incorporating micro/nanoscaled doping with varying amounts of Graphene Oxide (GO). A control group consisting of a PGAM without GO was also utilized, allowing for the analysis of the regulatory mechanism behind GO-doped PGAM. The findings indicated that a doping amount of 0.03 wt% of GO resulted in a maximum peak difference of 16.08 mN/g in the output force density of PGAM during multiple cycles, with a maximum change rate of 21.13%. The PGAM demonstrated a maximum output force density of 15.06 mN/g during a single cycle when doped with 0.03 wt% of GO. Furthermore, electrochemical analysis of the PGAM revealed that at the same doping amount of 0.03 wt%, the specific capacitance reached its peak value of 324 nF·cm−2, while the resistance reached its minimum value of 1.61 Ω. In summary, the incorporation of GO doping has been found to enhance the intelligent electric response properties of PGAM, thereby offering a novel approach for the advancement of flexible actuators exhibiting superior intelligent electric response property.

A Comparative Analysis of the Synoptic Conditions of Two Heavy Rainfall Cases West of the Pearl River Estuary

This paper compares the synoptic-scale circulation and thermodynamic conditions of two representative heavy rainfall cases that were concentrated west of the Pearl River Estuary under different seasonal backgrounds. The first case occurred in the early rainy season, with strong precipitation lasting for several hours. The second case occurred in the late rainy season, with extreme flash downpour in just two hours. The analysis reveals that the main cause was different for the two rainfall cases. The main cause of the first rainfall case was converging polar cold air and marine warm air that formed a synoptic scale front that drove the strong ascent. The main cause of the second case was a cold backflow from the Taiwan Strait, resulting in a sharply contrasting equivalent potential temperature front and triggering very strong upward motion. The moist potential vorticity (MPV) showed a negative value before both rainstorms, indicative of the importance of convective instability. A sandwich-like configuration of the MPV led to the development of strong vertical motion for the second case.

A sandwich-like configuration with a signal amplification strategy using a methylene blue/aptamer complex on a heterojunction 2D MoSe2/2D WSe2 electrode: Toward a portable and sensitive electrochemical alpha-fetoprotein immunoassay.

Liver cancer is one of the most common global health problems that features a high mortality rate. Alpha-fetoprotein (AFP) is a potential liver cancer biomarker for the diagnosis of liver cancer. The quantitative detection of AFP at an ultratrace level has important medical significance. Using the reaction of the antibody-antigen pair in an immunosensor enables the sensitive and selective AFP assay. Finding a strategy in signal generation and amplification is challenging to fabricate new sensitive electrochemical immunosensors for AFP detection. This study demonstrates the construction of a simple, reliable, and label-free immunosensor for the detection of AFP on a smart phone. Exfoliated two-dimensional (2D) molybdenum diselenide (MoSe2) and 2D tungsten diselenide (WSe2) were employed to modify the disposable screen-printed carbon electrode (SPCE) to use as the electrochemical platform, which is affixed to a small potentiostat connected to a smart phone. The modified electrode offers antibody immobilization and allows detection of AFP via an immunocomplex forming a sandwich-like configuration with the AFP-corresponding aptamer. A heterojunction 2D MoSe2/2D WSe2 composite improves the SPCE's reactivity and provides a large surface area and good adsorption capacity for the immobilizing antibodies. The signal generation for the immunosensor is from the electrochemical response of methylene blue (MB) intercalating into the aptamer bound on the electrode. The response for the proposed sandwich-like immunosensor is proportional to the AFP concentration (1.0-50,000 pg ml-1). The biosensor has potential for the development of a simple and robust point-of-care diagnostic platform for the clinical diagnosis of liver cancer, achieving a low limit of detection (0.85 pg ml-1), high sensitivity, high selectivity, good stability, and excellent reproducibility.

Resistance-Based Lateral Flow Immunosensor with a NFC-Enabled Smartphone for Rapid Diagnosis of Leptospirosis in Clinical Samples.

Leptospirosis is one of the most life-threatening tropical diseases caused by pathogenic Leptospira. To date, a diagnostic device that offers rapid and sensitive detection of leptospires has been still in demand for proper treatment to reduce the mortality rate. Herein, we create a resistance-based lateral flow immunosensor diagnosis device (R-LFI) that integrates near-field communication (NFC) with a portable smartphone for leptospiral detection in clinical samples. A specific monoclonal antibody against the pathogen was coated on a nitrocellulose membrane (NCM) where the test line was collocated. Two electrodes with a sandwich-like configuration were installed employing a conductive double-sided adhesive tape and connected with a NFC smartphone-based detection system. A half-sandwich immunocomplex formation induced high proton conduction, resulting in a considerable decrement in resistive response. The performance of the R-LFI sensor was evaluated using recombinant LipL32 (rLipL32), Leptospira interrogans, and clinical samples. The R-LFI device exhibited linear responses toward rLipL32 protein in phosphate buffer and L. interrogans-spiked healthy human serum samples within the concentration ranging from 1 to 1000 ng mL-1 (limit of detection (LOD): 0.29 ng mL-1) and from 104 to 106 cell mL-1 (LOD: 4.89 × 103 cell mL-1), respectively. Our R-LFI sensor successfully detected L. interrogans-positive clinical samples as confirmed by polymerase chain reaction (PCR). This platform offers high specificity, selectivity, simplicity, miniscule sample volume, and no labeling element requirement. These desirable features make it particularly suitable for countries where medical facilities and resources are limited.

Design and performance of flexible polymeric piezoelectric energy harvesters for battery-less tyre sensors

A piezoelectric energy harvester for battery-less tyre sensors has been developed. It consists of two key elements: (a) a piezoelectric material—polyvinylidene difluoride (PVDF) film and (b) an electrode—a conductive elastomer filled with carbon black and single-wall carbon nanotubes (SWCNTs). It was designed as a flexible patch in a sandwich-like configuration, which can be mounted onto the inner liner of a tyre. The patch was fabricated by inserting a PVDF film in between two conductive elastomer sheets. The development started with improving the conductivity of the elastomer by adding 6 wt% of SWCNT masterbatch. The adhesion between the interfaces was improved through surface modification of the PVDF film by introducing oxygen functional groups via a plasma treatment and further modification with a thiocyanate silane. The successful surface modification of the PVDF film was affirmed by x-ray photoelectron spectroscopy. T-peel and fatigue tests showed durable and stable adhesion between PVDF and conductive elastomer, confirming that the silane can effectively bridge the two components. A glueing method is proposed to adhere the patch to the tyre inner liner compound. The harvester is estimated to sufficiently power a reference tyre sensor, producing 28 μW cm−2.

Characterization of the hierarchical architecture and micromechanical properties of walnut shell (Juglans regia L.)

In the present work a comprehensive characterization of the hierarchical architecture of the walnut shell (Juglans regia L.) was carried out using scanning electron microscopy (SEM), atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). Furthermore, micromechanical properties (hardness, HIT and elastic modulus, EIT) of plant tissues were evaluated at cell wall level by applying the instrumented indentation technique (IIT). The complex architecture of the material was described in terms of four hierarchical levels (HL): endocarp (H1), plant tissues (H2), plant cells (H3) and cell wall (H4). Our findings revealed that the walnut shell consists of a multilayer structure (sclerenchyma tissue, ST; interface tissue, IT; porous tissue, PT; and flattened parenchyma tissue, FPT), where differences in the microstructure and composition of plant tissues generate parallel gradients along the cross-section. The indentation tests showed a functional gradient with a sandwich-like configuration, i.e., a lightweight and soft layer (PT, HIT = 0.04 GPa) is located between two dense and hard layers (ST, HIT = 0.33 GPa; FPT, HIT = 0.28 GPa); where additionally there is an interface between ST and PT (IT, HIT = 0.16 GPa). This configuration is a successful strategy designed by nature to improve the protection of the kernel by increasing the strength of the shell. Therefore, the walnut shell can be considered as a functionally graded material (FGM), which can be used as bioinspiration for the design of new functional synthetic materials. In addition, we proposed some structure-property-function relationships in the whole walnut shell and in each of the plant tissues.

Strategic fabrication of efficient photo-responsive semiconductor electronic diode-devices by Bovine Serum Albumin protein-based Cu(II)-metallohydrogel scaffolds

Bovine Serum Albumin protein-based two fascinating functional self-healing Cu(II) metallohydrogel scaffolds (MD1 and MD2) have been studied for the development of metal-semiconductor junction based Schottky diode device. Multiple metal-semiconductor (MS) junction devices, offering the sandwich-like configuration of Indium tin oxide (ITO)/ metallogel/Aluminium (Al), have been made-up to investigate the electrical properties of the synthesized metallohydrogel materials. Optical characterizations including optical band gap measurement have been carried out using Tauc's equation for both the metallohydrogels. The current-voltage (I-V) characteristics of just made-up devices are studied under irradiation and non- irradiation conditions to explore the electrical features through investigating the charge transport phenomenon. The electrical conductivity gets estimated as 3.13 × 10−5 S.m−1 and 2.69 × 10−5 S.m−1 for MD1 and MD2 under dark condition, and 11.06 × 10−5 S.m−1 and 5.99 × 10−5 S.m−1 for MD1 and MD2, respectively, in photo-irradiation. The measured optical and electrical properties of MD1 and MD2 metallohydrogels are thoroughly investigated and the data indicates that MD1 and MD2 metallohyrogels are semiconducting in nature with excellent photo-responsive behaviour. Moreover, the representative I − V characteristic of the MD1 and MD2 metallohydrogels at both irradiation and non-irradiation conditions represents the nonlinear rectifying behaviour, a typical signature for Schottky diode (SD).

Vertical-Flow Paper Sensor for On-Site and Prompt Evaluation of Chloride Contamination in Concrete Structures.

Corrosion occurring in reinforced concrete has turned into a primary concern of the current century, concrete being the most ubiquitous and predominant material used in the construction industry. Among the many interrelated processes that trigger corrosion of metallic reinforcements, the penetration of chloride ions into the concrete matrix is the most insidious threat. Herein, we developed the first electrochemical device entirely made of paper that allows for the direct, prompt, and noninvasive evaluation of free chloride ion contamination in concrete-based constructions. Our device is based on a three-layer wax-modified filter paper, consisting of two Ag/AgCl screen-printed electrodes that are interfaced by a junction pad in a sandwich-like configuration. Filter paper allows for generating a vertical-flow potentiometric device capable of measuring the electrochemical potential between two solutions containing different concentrations of chloride ions, which are separately drop-cast on the top and bottom layers. After demonstrating the analytical performance of the device, the same principle was applied to the evaluation of the chloride contents in different concrete samples, exploiting paper as a suitable interfacing material for potentiometric measurements on the cement solid surface. Laboratory-prepared concrete samples with known chloride contents were first assessed, and then, the paper-based vertical-flow device was applied to real concrete structures at the Giacomo Manzù Museum (Ardea, Italy) for the evaluation of chloride contamination caused by the proximity to the seaside. The capability of our device to provide timely warning of the risk conditions of concrete-based artifacts was demonstrated.

A low-cost PCR instrument for molecular disease diagnostics based on customized printed circuit board heaters.

This article describes the fabrication of a low-cost Polymerase Chain Reaction (PCR) instrument to detect diseases. In order to reduce the instrument price and simplify construction we developed an alternative fabrication process, transforming conventional printed circuit boards (PCB) in heating elements, avoiding the use of aluminum heating/cooling blocks and Peltier devices. To cool down the reaction a simple computer fan was used. The vial holder was fabricated using two double side PCB boards assembled in a sandwich-like configuration. The bottom PCB has a resistance of 0.9 Ω used to heat the reaction mix, while the top layer has a resistance of 1.1 Ω to heat the vial body, preventing vapor condensation. The top board was maintained at ~ 110 ± 1°C during all cycles. The final device was able to heat and cool down the reaction at rates of ~ 2.0°C/s, a rate comparable to commercial thermocyclers. An SMD NTC thermistor was used as temperature sensors, and a PID (proportional-integral-derivative) control algorithm was implemented to acquire and precisely control the temperature. We also discuss how the instrument is calibrated. The device was tested successfully for the amplification of T. pallidum (Syphilis) bacterial DNA and Zika virus RNA samples, showing similar performance to a commercial PCR instrument.

Mechanistic aspects of ammonia synthesis on Ta3N5 surfaces in the presence of intrinsic nitrogen vacancies.

A possible dinitrogen activation and the ammonia synthesis mechanism were studied on the (100), (010) and (001) surfaces of Ta3N5 that contain intrinsic nitrogen vacancies. The study suggests that intrinsic nitrogen vacancies can become catalytic centers for the ammonia synthesis reaction on Ta3N5via a Langmuir-Hinshelwood mechanism, which may explain the moderate production of ammonia at high temperatures. In the proposed mechanism, dinitrogen is activated in a peculiar side on a sandwich-like configuration between two surface Ta atoms. Calculation of reaction activation barriers suggests that the mechanism proceeds via moderate barriers but some elementary reaction steps involve the strong adsorption of ammonia which appears to poison the surface catalytic sites on Ta3N5.

Characterization of a Sandwich PLGA-Gallic Acid-PLGA Coating on Mg Alloy ZK60 for Bioresorbable Coronary Artery Stents.

Absorbable magnesium stents have become alternatives for treating restenosis owing to their better mechanical properties than those of bioabsorbable polymer stents. However, without modification, magnesium alloys cannot provide the proper degradation rate required to match the vascular reform speed. Gallic acid is a phenolic acid with attractive biological functions, including anti-inflammation, promotion of endothelial cell proliferation, and inhibition of smooth muscle cell growth. Thus, in the present work, a small-molecule eluting coating is designed using a sandwich-like configuration with a gallic acid layer enclosed between poly (d,l-lactide-co-glycolide) layers. This coating was deposited on ZK60 substrate, a magnesium alloy that is used to fabricate bioresorbable coronary artery stents. Electrochemical analysis showed that the corrosion rate of the specimen was ~2000 times lower than that of the bare counterpart. The released gallic acid molecules from sandwich coating inhibit oxidation by capturing free radicals, selectively promote the proliferation of endothelial cells, and inhibit smooth muscle cell growth. In a cell migration assay, sandwich coating delayed wound closure in smooth muscle cells. The sandwich coating not only improved the corrosion resistance but also promoted endothelialization, and it thus has great potential for the development of functional vascular stents that prevent late-stent restenosis.

Molecular Tetrahedrons as Selective and Efficient Ion Transporters via a Two-Station Swing-Relay Mechanism

The traditional approach to utilizing an ion-relay mechanism for ion transport requires three or more ion-relay stations. Herein, we describe a novel strategy, incorporating a swing action to reali...

A two-membrane electrodialytic carbonate eluent generator for ion chromatography

A two-membrane electrodialytic carbonate eluent generator (EDG) for ion chromatography (IC) is described. It is in a sandwich-like configuration, in which the central eluent channel is spatially isolated from two outer regenerant channels by stacked cation exchange membranes (CEMs) and anion exchange membranes (AEMs). A platinum screen electrode is placed in each of two outer regenerant channels. The electrode at the CEMs side is set as an anode with respect to the electrode at the AEMs side being cathode. Potassium carbonate and/or bicarbonate solution is pumped into the regenerant channel as feed solution. The electromigration of carbonate and/or bicarbonate and potassium from feed solution respectively through AEMs and CEMs will form a gas-free eluent. With this configuration, ion transport behavior through AEMs was explored. The device demonstrated good reproducibility, as indicated by the relative standard deviation of retention time of less than 0.08%.

Electrodialysis Pump Based on Enhanced Water Dissociation of Bipolar Membrane.

We describe a novel micropump mode-electrodialysis pump (EDP), which is based on the recombination of hydrogen and hydroxyl ions generated by enhanced water dissociation of bipolar membrane (BPM). The pump is in a sandwich-like configuration in which the central production channel is spatially isolated from two outer regenerant chambers by a BPM, respectively. Both BPMs are put at the same direction, in which the anion exchange membrane (AEM) side is facing the anode with respect to the cation exchange membrane (CEM) side facing the cathode. Pure water as the feed solution flows through the regenerant chambers at a conventional flow rate (e.g., 0.2 mL/min). Under the electric field, enhanced water dissociation at the junction layer of BPM will occur, generating hydroxyl and hydrogen ions. Their electrodialytic migration into the central channel will recombine water and its flow rate is correlated with the applied current. The pump shows near-ideal Faradaic efficiency and at least 0.8 μL/min can be achieved by controlling the current. The produced water is near neutral and obvious enrichment of trace impurity anions is observed in the production channel.

Heterovalent Ga3+ doping in solution-processed Cu2ZnSn(S,Se)4 solar cells for better optoelectronic performance

A sandwich-like configuration was constructed through the introduction of a heterovalent Ga3+ intermediate layer, which facilitates the improvement of the performance of Cu2ZnSn(S,Se)4 solar cells.

Engineering zero modes, Fano resonance, and Tamm surface states in the waveguide-array realization of the modified Su-Schrieffer-Heeger model.

In this article, we developed a generalized coupled-mode theory for mixing an isolated state with a continuum having an intrinsic energy gap, which dubbed as "the bound states in the gapped continuum" (BIGC). We investigated the mixture interaction by mimicking the Su-Schrieffer-Heeger model in an optical coupled waveguide array (WA), and presented a unified engineering mechanism for topologically-protected zero modes, Fano resonance, and Tamm surface states, even though those phenomena are diverse in topological insulators, atomic physics and semiconductors, respectively. By tuning the on-site potential and coupling strength of the isolated state, we found the unified operating characteristics for zero modes, Fano resonance, and Tamm states, with demonstrating their localization, transmission spectra, and distinct evolution dynamics explicitly. As an extension for triple-modes coupling, two special sandwich-like configurations are studied: the isolated-continuous-isolated and continuous-isolated-continuous configurations lead to adiabatic eliminations and domain walls, respectively, revealing possible applications and wide connections in many fields of physics and optics.

Sputtered SiC coatings for radiative cooling and light absorption

The outstanding thermomechanical and broadband spectral absorptance of silicon carbide (SiC) coatings makes it a promising material for high-performance optoelectronics devices and photothermal applications. We propose sputtered SiC coatings to develop: (i) broadband infrared emitters for passive radiative cooling and (ii) a spectrally selective ultrathin nanocomposite absorber. For radiative cooling, a proof of concept device has been fabricated by topping the as-sputtered 2.5-μm-thick SiC films with a single pair of distributed Bragg’s reflector (DBR). Owing to the infrared surface polariton resonances of SiC, broadband infrared emissivity of 0.8 is achieved in atmospheric transparency window (8 to 14 μm). The higher refractive index contrast (Δn) in DBR is achieved by depositing high refractive index dense Si film on top of low refractive index nanoporous SiO2, which was fabricated by oblique angle deposition approach. A single pair of DBR on top of SiC considerably reduces the absorption of the overall solar spectrum by 18%. In addition, impact of various materials and number of pairs of DBRs on radiative cooling are also numerically investigated. We also designed and fabricated SiC-based spectrally selective solar absorber coatings. An ultrathin SiC-based nanocomposite absorber with sandwich-like configuration consisting of SiC/Ag-SiC/SiC on reflective substrate has exhibited an outstanding absorptance of 91.24% in the wavelength range of 280 to 2000 nm. The surface plasmon polaritons of metal inclusion within the SiC matrix of an ultrathin nanocomposite (40 nm) layer has contributed to broadband light absorption, whereas the top most layer of SiC (40 nm) acts as antireflection layer. Conclusively, the versatility of sputtered SiC coatings has proven to be promising for radiative cooling and spectrally selective solar absorbers.

Elasticity solution for orthotropic FGM plates with dissimilar stiffness coefficient variations

Dissimilar orthotropic stiffness coefficient variations are a characteristic feature of unidirectionally reinforced fiber composites with a variable fiber volume fraction, but have not been commonly considered in the literature. The objective of this work is to account for them and obtain a three-dimensional elasticity solution with specific reference to simply supported rectangular plates. The analysis involves the solution of variable coefficient governing equations using the power series approach. For a graphite–epoxy plate with a sandwich-like configuration, results useful as a benchmark for future comparisons are tabulated for a specific power law variation of the volume fraction. It is shown that the thickness-wise variations of displacements and stresses are significantly nonlinear, and such variations are not captured correctly by the classical plate theory. Further, on the basis of the elasticity solution, the relative benefit of using a sandwich-like configuration versus a homogeneous plate is shown to depend on the span-to-thickness ratio and to decrease significantly as the plate becomes thick.