Stretchable self‐healing supercapacitors (SCs) can operate under extreme deformation and restore their initial properties after damage with considerably improved durability and reliability, expanding ...their opportunities in numerous applications, including smart wearable electronics, bioinspired devices, human–machine interactions, etc. It is challenging, however, to achieve mechanical stretchability and self‐healability in energy storage technologies, wherein the key issue lies in the exploitation of ideal electrode and electrolyte materials with exceptional mechanical stretchability and self‐healing ability besides conductivity. Conductive hydrogels (CHs) possess unique hierarchical porous structure, high electrical/ionic conductivity, broadly tunable physical and chemical properties through molecular design and structure regulation, holding tremendous promise for stretchable self‐healing SCs. Hence, this review is innovatively constructed with a focus on stretchable and self‐healing CH based electrodes and electrolytes for SCs. First, the common synthetic approaches of CHs are introduced; then the stretching and self‐healing strategies involved in CHs are systematically elaborated; followed by an explanation of the conductive mechanism of CHs; then focusing on CH‐based electrodes and electrolytes for stretchable self‐healing SCs; subsequently, application of stretchable and self‐healing SCs in wearable electronics are discussed; finally, a conclusion is drawn along with views on the challenges and future research directions regarding the field of CHs for SCs.
Conductive hydrogels (CHs) are a new class of soft functional materials that have recently found application in flexible energy storage devices such as batteries and supercapacitors (SCs). Herein, the promise of CHs in this emerging field is demonstrated through summarizing their roles as ideal electrode and electrolyte materials for stretchable and self‐healing SCs.
In the emerging Internet of Things, stretchable antennas can facilitate wireless communication between wearable and mobile electronic devices around the body. The proliferation of wireless devices ...transmitting near the human body also raises interference and safety concerns that demand stretchable materials capable of shielding electromagnetic interference (EMI). Here, an ultrastretchable conductor is fabricated by depositing a crumple‐textured coating composed of 2D Ti3C2Tx nanosheets (MXene) and single‐walled carbon nanotubes (SWNTs) onto latex, which can be fashioned into high‐performance wearable antennas and EMI shields. The resulting MXene‐SWNT (S‐MXene)/latex devices are able to sustain up to an 800% areal strain and exhibit strain‐insensitive resistance profiles during a 500‐cycle fatigue test. A single layer of stretchable S‐MXene conductors demonstrate a strain‐invariant EMI shielding performance of ≈30 dB up to 800% areal strain, and the shielding performance is further improved to ≈47 and ≈52 dB by stacking 5 and 10 layers of S‐MXene conductors, respectively. Additionally, a stretchable S‐MXene dipole antenna is fabricated, which can be uniaxially stretched to 150% with unaffected reflected power <0.1%. By integrating S‐MXene EMI shields with stretchable S‐MXene antennas, a wearable wireless system is finally demonstrated that provides mechanically stable wireless transmission while attenuating EM absorption by the human body.
2D titanium carbide–based ultrastretchable conductors are fabricated by harnessing the surface instability of pre‐stretched latex, showing strain‐invariant performance in stretchable electromagnetic interference (EMI) shields and wearable wireless communicators, respectively. Finally, a wearable antenna with on‐site EM protection for the human body is demonstrated, which exhibits mechanically stable and efficient wireless communication and shielding performance.
Scaling the synergistic properties of MXene nanosheets to microporous aerogel architectures requires effective strategies to overcome the nanosheet restacking without compromising MXene's ...advantageous properties. Traditional assembly approaches of 3D MXene aerogels normally involve external binders/templates and/or additional functionalization, which sacrifice the electrical conductivities and electrochemical activities of MXene aerogels. Herein, inspired by the hierarchal scale textures of Phrynosoma cornutum, a crumple‐textured Ti3C2Tx MXene platform is engineered to facilitate Mg2+‐induced assembly, enabling conformal formation of large‐area Mg2+‐MXene aerogels without polymeric binders. Through a doctor blading technique and freeze drying, the Mg2+‐MXene aerogels are produced with customized shapes/dimensions, featuring high surface area (140.5 m2 g−1), superior electrical conductivity (758.4 S m−1), and high robustness in water. The highly conductive MXene aerogels show their versatile applications from macroscale technologies (e.g., electromagnetic interference shielding and capacitive deionization (CDI)) to on‐chip electronics (e.g., quasi‐solid‐state microsupercapacitors (QMSCs)). As CDI electrodes, the Mg2+‐MXene aerogels exhibit high salt adsorption capacity (33.3 mg g−1) and long‐term operation reliability (over 30 cycles), showing a superb comparison with the literature. Also, the QMSCs with interdigitated Mg2+‐MXene aerogel electrodes demonstrate high areal capacitances (409.3 mF cm−2) with superior power density and energy density compared with other state‐of‐art QMSCs.
Inspired by the lizard's hierarchal scale textures, a crumple‐textured Ti3C2Tx MXene platform is engineered to facilitate metal ion‐induced assembly, enabling conformal formation of large‐area MXene aerogels without polymeric binders. The resulting MXene aerogels are produced with high structural stability, superior electrical conductivity, and efficient electrochemical performance. The MXene aerogels can be applied to electromagnetic interference shielding, capacitive deionization, and microsupercapacitors.
Biochar is a carbon (C) rich product of thermochemical conversion of organic material that is used as a soil amendment due to its resistance to decomposition and its influence on nutrient dynamics; ...however, individual studies on biochar effects on phosphorus (P) and nitrogen (N) have proven inconsistent. Herein, we performed a meta-analysis of 124 published studies to evaluate the influence of biochar on available P, microbial biomass P (MBP), and inorganic N (NO3−-N and NH4+-N) in global agricultural ecosystems. Overall, the results showed that biochar applications significantly increased surface soil available P by 45% and MBP by 48% across the full range of biochar characteristics, soil type, or experimental conditions. By contrast, biochar addition to soil reduced NO3−-N concentrations by 12% and NH4+-N by 11%, but in most cases biochar added in combination with organic fertilizer significantly increased soil NH4+-N compared to controls. Biochar C:N ratio and biochar source (feedstock) strongly influenced soil P availability response to biochar where inorganic N was most influenced by biochar C:N ratio and soil pH. Biochar made from manure or other low C:N ratio materials, generated at low temperatures, or applied at high rates were generally more effective at enhancing soil available P. It is important, however, to note that most negative results were observed in short-term (<6 months) where long-term studies (>12 months) tended to result in neutral to modest positive effects on both P and N. This meta-analysis indicates that biochar generally enhances soil P availability when added to soils alone or in combination with fertilizer. These findings provide a scientific basis for developing more rational strategies toward widespread adoption of biochar as a soil amendment for agricultural P and N management.
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•Biochar effects on agricultural soil P and N availability was examined in a meta-analysis.•Biochar additions increased soil available P regardless of analytic method.•Biochar reduced soil inorganic N in agricultural soils.•Biochar characteristics strongly influenced the response of soil available P.
To achieve fully flexible microwave devices, we investigated flexible polymers in terms of chemical, mechanical, and electrical properties. Moreover, the fabrication techniques for polymer-based ...microwave devices have been developed to address chemical adhesion and demolding issues. Finally, based on formulated criteria, we have developed recipes for low-loss (0.001), low-Dk (1.73) flexible dielectric materials and have applied them to the microstrip and CPW transmission lines. The transmission losses of the microstrip and CPW lines are as low as 0.065 and 0.034 dB/cm at 2.5 GHz, respectively, which are comparable to those for rigid PCBs. The effects of various materials on microwave performance have been analyzed, from which we show that the acceptable frequency limits for using our fully flexible microwave devices are 7 GHz for microstrip lines and 10 GHz for CPW lines. The proposed molding process allows us to step out from 2-D PCB designs and build 3-D structures or hybrid PCB-3-D components with a certain freedom in material properties. The new material exhibits unique mechanical properties, which extend the material's application to other fields. In addition, it has been found that the polymer-based devices have significant performance improvements at elevated temperatures, which can be exploited in a high-temperature application.
Lookup-Table-Based Automated Rectifier Synthesis Gao, Si-Ping; Zhang, Hao; Ngo, Tung ...
IEEE transactions on microwave theory and techniques,
12/2020, Letnik:
68, Številka:
12
Journal Article
Recenzirano
Rectifier design nowadays relies heavily on iterative optimization, which is prone to fall into local minima or end up with no solution. Such a procedure is time-consuming and requires lots of ...experience from designers. Guided rectifier synthesis with the least engagement of optimization is thus desired. In this article, a lookup-table-based automated rectifier synthesis method is presented. The lookup tables are essentially contour maps of the rectifier performance indicators on a 2-D plane of the absorbed RF power <inline-formula> <tex-math notation="LaTeX">P_{\mathrm {abs}} </tex-math></inline-formula> and the load resistance <inline-formula> <tex-math notation="LaTeX">R_{\mathrm {L}} </tex-math></inline-formula>. To establish lookup tables, an improved rectification model is developed, allowing for accurate data generation at any specific coordinate (<inline-formula> <tex-math notation="LaTeX">R_{\mathrm {L}},P_{\mathrm {abs}} </tex-math></inline-formula>). High-quality lookup tables are thus established with the equidistant data over the (<inline-formula> <tex-math notation="LaTeX">R_{\mathrm {L}},_{}P_{\mathrm {abs}} </tex-math></inline-formula>) plane. Based on the lookup tables, the optimal operating point (<inline-formula> <tex-math notation="LaTeX">R_{\mathrm {L}},_{}P_{\mathrm {abs}} </tex-math></inline-formula>) can be straightforwardly identified according to the requirement, facilitating the subsequent diode and topology selection and matching circuit design. The whole design flow is sequential and automated, only engaging fine-tuning in the final stage. Simulation and measurement results validate the proposed methodology.
Curcumin and Diabetes: A Systematic Review Zhang, Dong-wei; Fu, Min; Gao, Si-Hua ...
Evidence-based complementary and alternative medicine,
01/2013, Letnik:
2013
Journal Article
Recenzirano
Odprti dostop
Turmeric (Curcuma longa), a rhizomatous herbaceous perennial plant of the ginger family, has been used for the treatment of diabetes in Ayurvedic and traditional Chinese medicine. The active ...component of turmeric, curcumin, has caught attention as a potential treatment for diabetes and its complications primarily because it is a relatively safe and inexpensive drug that reduces glycemia and hyperlipidemia in rodent models of diabetes. Here, we review the recent literature on the applications of curcumin for glycemia and diabetes-related liver disorders, adipocyte dysfunction, neuropathy, nephropathy, vascular diseases, pancreatic disorders, and other complications, and we also discuss its antioxidant and anti-inflammatory properties. The applications of additional curcuminoid compounds for diabetes prevention and treatment are also included in this paper. Finally, we mention the approaches that are currently being sought to generate a “super curcumin” through improvement of the bioavailability to bring this promising natural product to the forefront of diabetes therapeutics.
In this article, an effective method to characterize microwave connectors over temperature is presented, which can be useful for accurate characterization of devices or materials under temperature ...stress. First, calibration standards made of thermal-stable RF laminate are used, allowing for assuming constant standard coefficients over temperatures and greatly simplifying the process. Second, all the standards are measured concurrently with a four-port VNA for each temperature of interest, avoiding additional errors due to temperature difference or uncertainties caused by connector reconnections in a sequential measurement. Finally, a linear characterization formulation is employed, enabling an error sensitivity analysis. From the analysis, one is able to identify error-resilient standard-equation combinations, to do the data sanity check, and more importantly to determine the optimal standard length toward a wide effective bandwidth. An end-launch connector is characterized at 0 °C-100 °C, showing the effectiveness and usefulness of the proposed method.
With tens of thousands of plant species on earth, we are endowed with an enormous wealth of medicinal remedies from Mother Nature. Natural products and their derivatives represent more than 50% of ...all the drugs in modern therapeutics. Because of the low success rate and huge capital investment need, the research and development of conventional drugs are very costly and difficult. Over the past few decades, researchers have focused on drug discovery from herbal medicines or botanical sources, an important group of complementary and alternative medicine (CAM) therapy. With a long history of herbal usage for the clinical management of a variety of diseases in indigenous cultures, the success rate of developing a new drug from herbal medicinal preparations should, in theory, be higher than that from chemical synthesis. While the endeavor for drug discovery from herbal medicines is “experience driven,” the search for a therapeutically useful synthetic drug, like “looking for a needle in a haystack,” is a daunting task. In this paper, we first illustrated various approaches of drug discovery from herbal medicines. Typical examples of successful drug discovery from botanical sources were given. In addition, problems in drug discovery from herbal medicines were described and possible solutions were proposed. The prospect of drug discovery from herbal medicines in the postgenomic era was made with the provision of future directions in this area of drug development.
In this paper, a 2-stage compact wideband low-noise amplifier (LNA) monolithic microwave integrated circuit (MMIC) with multiple resistive feedback (MRFB) is presented. From the DC point of view, the ...proposed MRFB functions as a self-biasing structure to bias transistors in the optimal condition, improving the noise figure (NF) and linearity. Meanwhile, by employing MRFB with source degeneration and input inductor, the proposed LNA achieves wideband flat gain at the AC side. In comparison with traditional topologies, a wide bandwidth of more than 11.5 GHz with low noise figure of less than 2.5 dB can be achieved. To verify the proposed LNA structure, a chip prototype is fabricated in a 0.15-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> GaAs E-mode pHEMT process with a compact die size of only 0.75 mm2 including all the testing pads. From the measurement results, the proposed LNA circuit features a 1.0 to 12.5 GHz 3-dB working bandwidth (172% fractional bandwidth), 23.6 peak gain, 1.51 dB minimum NF, 66.7± 15 ps group delay, and 24.3/12.6 dBm best OIP3/OP1dB, respectively. The total DC power is around 87.5 mW from a single 2.5-V power supply.
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