Highlights Bioelectronic devices have revolutionized the course of therapeutic treatment with their ability to harness neuronal activities in the human body. Recent advances in the field of soft, stretchable and biocompatible materials have enabled the development of bioelectronics to treat wide range of chronic ailments and disorders. Such treatments involve the confluence of electronics with neuronal cells or tissues, and mostly require surgical operation to implant the bioelectronic device. For recording neural activities and programming the device non-invasively, copious amount of research is in progress to devise wireless technology enabled bioelectronics. This paper discusses the latest developments in wireless bioelectronic devices for organ specific treatments, including gastrointestinal tract monitoring, retinal prosthesis, auditory nerve and brain stimulation. Major highlights include seminal components that mediate the overall wireless operation, such antennas, rectifiers, amplifier and integrated circuits. Moreover, the constituting materials of antennas, operational frequency and their integration with other electronic components are discussed. Replete perspective on the strategies to energize bioelectronics using wireless power transfer is explained. Communication protocols for biotelemetry are also discussed.The integration of electronics and biology has spawned bioelectronics and opened exciting opportunities to fulfill the unmet needs of therapeutic treatments. Recent developments in nanoelectronics and soft and biocompatible materials have shown potential applicability to clinical practices, including physiological sensing, drug delivery, cardiovascular monitoring, and brain stimulation. To date, most bioelectronic devices require wired connections for electrical control, making their implantation complicated and inconvenient for patients. As an alternative, wireless technology is proliferating to create bioelectronics that offer noninvasive control, biotelemetry, and wireless power transfer (WPT). This review paper provides a comprehensive overview of wireless bioelectronics and ongoing developments in their applications for organ-specific treatments, including disorders and dysfunctions. The main emphasis is on delineating the key features of antennas, namely their radiation characteristics, materials, integration with rest of the electronics, and experimental setup. Although the recent progress in wireless mediated bioelectronics is expected to enhance the control of its functionalities, there are still numerous challenges that need to be addressed for commercialization, as well as to address ever-expanding evolving future therapeutic targets.
Far-field wireless power transfer (WPT) is a major breakthrough technology that will enable the many anticipated ubiquitous Internet of Things (IoT) applications associated with fifth generation (5G), sixth generation (6G), and beyond wireless ecosystems. Rectennas, which are the combination of rectifying circuits and antennas, are the most critical components in far-field WPT systems. However, compact application devices require even smaller integrated rectennas that simultaneously have large electromagnetic wave capture capabilities, high alternating current (AC)-to-direct current (DC) (AC-to-DC) conversion efficiencies, and facilitate a multifunctional wireless performance. This paper reviews various rectenna miniaturization techniques such as meandered planar inverted-F antenna (PIFA) rectennas; miniaturized monopole- and dipole-based rectennas; fractal loop and patch rectennas; dielectric-loaded rectennas; and electrically small near-field resonant parasitic rectennas. Their performance characteristics are summarized and then compared with our previously developed electrically small Huygens rectennas that are proven to be more suitable for IoT applications. They have been tailored, for example, to achieve battery-free IoT sensors as is demonstrated in this paper. Battery-free, wirelessly powered devices are smaller and lighter in weight in comparison to battery-powered devices. Moreover, they are environmentally friendly and, hence, have a significant societal benefit. A series of high-performance electrically small Huygens rectennas are presented including Huygens linearly-polarized (HLP) and circularly-polarized (HCP) rectennas; wirelessly powered IoT sensors based on these designs; and a dual-functional HLP rectenna and antenna system. Finally, two linear uniform HLP rectenna array systems are considered for significantly larger wireless power capture. Example arrays illustrate how they can be integrated advantageously with DC or radio frequency (RF) power-combining schemes for practical IoT applications.
The fifth generation (5G) network communication systems operate in the millimeter waves and are expected to provide a much higher data rate in the multi-gigabit range, which is impossible to achieve using current wireless services, including the sub-6 GHz band. In this work, we briefly review several existing designs of millimeter-wave phased arrays for 5G applications, beginning with the low-profile antenna array designs that either are fixed beam or scan the beam only in one plane. We then move on to array systems that offer two-dimensional (2D) scan capability, which is highly desirable for a majority of 5G applications. Next, in the main body of the paper, we discuss two different strategies for designing scanning arrays, both of which circumvent the use of conventional phase shifters to achieve beam scanning. We note that it is highly desirable to search for alternatives to conventional phase shifters in the millimeter-wave range because legacy phase shifters are both lossy and costly; furthermore, alternatives such as active phase shifters, which include radio frequency amplifiers, are both expensive and power-hungry. Given this backdrop, we propose two different antenna systems with potential for the desired 2D scan performance in the millimeter-wave range. The first of these is a Luneburg lens, which is excited either by a 2D waveguide array or by a microstrip patch antenna array to realize 2D scan capability. Next, for second design, we turn to phased-array designs in which the conventional phase shifter is replaced by switchable PIN diodes or varactor diodes, inserted between radiating slots in a waveguide to provide the desired phase shifts for scanning. Finally, we discuss several approaches to enhance the gain of the array by modifying the conventional array configurations. We describe novel techniques for realizing both one-dimensional (1D) and 2D scans by using a reconfigurable metasurface type of panels.Graphical abstractA number of designs for scanning antennas are presented in this work to realize a one- or two-dimensional scan. The first of these is a Luneburg lens, together with a feed array, designed to realize a wide-angle scan The the second design is based on the use of an electronically reconfigurable phase shifter, which utilizes PIN or varactor diodes inserted between radiating slots in a curved waveguide to provide the desired phase shifts. Next, the paper introduces a novel design to realize both one- and two-dimensional scans, by using reconfigurable metasurface type of panels to provide a wide-angle beam-scanning performance, without compromising either the impedance match or the gain of the array. Additionally, the paper describes several techniques for enhancing the gain of the array to achieve gain levels as high as 30 dB, to render the scanning array competitive with reflectors, for instance.Download : Download high-res image (52KB)Download : Download full-size image
In this article, an omnidirectional dual-polarized antenna with synergetic electromagnetic and aerodynamic properties is propounded for high-speed diversity systems. The propounded antenna comprises a probe-fed cavity for horizontally polarized radiation and a microstrip-fed slot for vertical polarization. Double-layer metasurfaces are properly designed as artificial magnetic conductor boundaries with direct metal-mountable onboard installation and compact sizes. An attached wedge-shaped block is utilized for windage reduction in hydrodynamics. The propounded antenna is fabricated for design verification, and the experimental results agree well with the simulated ones. For vertical polarization, the operating bandwidth is in the range of 2.37–2.55 GHz, and the realized gain variation in the azimuthal radiation pattern is 3.67 decibels (dB). While an impedance bandwidth in the range of 2.45–2.47 GHz and a gain variation of 3.71 dB are also achieved for horizontal polarization. A port isolation more than 33 dB is obtained in a compact volume of 0.247λ0 × 0.345λ0 × 0.074λ0, where λ0 represents the wavelength in vacuum at the center frequency, wherein the wedge-shaped block is included. The propounded diversity antenna has electromagnetic and aerodynamic merits, and exhibits an excellent potential for high-speed onboard communication.
Trans-/cis-olefin isomers play a vital role in the petrochemical industry. The paucity of energy-efficient technologies for their splitting is mainly due to the similarities of their physicochemical properties. Herein, two new tailor-made anion-pillared ultramicroporous metal–organic frameworks (MOFs), ZU-36-Ni and ZU-36-Fe (GeFSIX-3-Ni and GeFSIX-3-Fe) are reported for the first time for the efficient trans-/cis-2-butene (trans-/cis-C4H8) mixture splitting by enhanced molecular exclusion. Notably, ZU-36-Ni unexpectedly exhibited smart guest-adaptive pore channels for trapping trans-C4H8 with a remarkable adsorption capacity (2.45 mmol∙g−1) while effectively rejecting cis-C4H8 with a high purity of 99.99%. The dispersion-corrected density functional theory (DFT-D) calculation suggested that the guest-adaptive behavior of ZU-36-Ni in response to trans-C4H8 is derived from the organic linker rotation and the optimal pore dimensions, which not only improve the favorable adsorption/diffusion of trans-C4H8 with optimal host–guest interactions, but also enhance the size-exclusion of cis-C4H8. This work opens a new avenue for pore engineering in advanced smart or adaptive porous materials for specific applications involving guest molecular recognition.
Sodium (Na) metal batteries with a high volumetric energy density that can be operated at high rates are highly desirable. However, an uneven Na-ion migration in bulk Na anodes leads to localized deposition/dissolution of sodium during high-rate plating/stripping behaviors, followed by severe dendrite growth and loose stacking. Herein, we engineer the Na hybrid anode with sodiophilic Na3Bi-penetration to develop the abundant phase-boundary ionic transport channels. Compared to intrinsic Na, the reduced adsorption energy and ion-diffusion barrier on Na3Bi ensure even Na+ nucleation and rapid Na+ migration within the hybrid electrode, leading to uniform deposition and dissolution at high current densities. Furthermore, the bismuthide enables compact Na deposition within the sodiophilic framework during cycling, thus favoring a high volumetric capacity. Consequently, the obtained anode was endowed with a high current density (up to 5 mA∙cm−2), high areal capacity (up to 5 mA·h∙cm−2), and long-term cycling stability (up to 2800 h at 2 mA∙cm−2).
Urbanization, population growth, and the accelerating consumption of food, energy, and water (FEW) resources bring unprecedented challenges for economic, environmental, and social (EES) sustainability. It is imperative to understand the potential impacts of FEW systems on the realization of the United Nation's Sustainable Development Goals (SDGs) as the world transitions from natural ecosystems to managed ecosystems at an accelerating rate. A major obstacle is the complexity and emergent behavior of FEW systems and associated networks, for which no single discipline can generate a holistic understanding or meaningful projections. We propose a research enterprise framework for promoting transdisciplinarity and top-down quantification of the interrelationships between FEW and EES systems. Relevant enterprise efforts would emphasize increasing FEW resource accessibility by improving coordinated interplays across sectors and scales, expanding and diversifying supply-chain networks, and innovating technologies for efficient resource utilization. This framework can guide the development of strategic solutions for diminishing the competition among FEW-consuming sectors in a region or country, and for minimizing existing inequalities in FEW availability when a sustainable development agenda is implemented.
Wellbore stability is essential for safe and efficient drilling during oil and gas exploration and development. This paper introduces a hydrophobic nano-silica (HNS) for use in strengthening the wellbore wall when using a water-based drilling fluid (WBF). The wellbore strengthening performance was studied using the linear swelling test, hot-rolling recovery test, and compressive strength test. The mechanism of strengthening the wellbore wall was studied by means of experiments on the zeta potential, particle size, contact angle, and surface tension, and with the use of a scanning electron microscope (SEM). The surface free energy changes of the shale before and after HNS treatment were also calculated using the contact angle method. The experimental results showed that HNS exhibited a good performance in inhibiting shale swelling and dispersion. Compared with the use of water, the use of HNS resulted in a 20% smaller linear swelling height of the bentonite pellets and an 11.53 times higher recovery of water-sensitive shale—a performance that exceeds those of the commonly used shale inhibitors KCl and polyamines. More importantly, the addition of HNS was effective in preventing a decrease in shale strength. According to the mechanism study, the good wellbore-strengthening performance of HNS can be attributed to three aspects. First, the positively charged HNS balances parts of the negative charges of clay by means of electrostatic adsorption, thus inhibiting osmotic hydration. Second, HNS fabricates a lotus-leaf-like surface with a micro-nano hierarchical structure on shale after adsorption, which significantly increases the water contact angle of the shale surface and considerably reduces the surface free energy, thereby inhibiting surface hydration. Third, the decrease in capillary action and the effective plugging of the shale pores reduce the invasion of water and promote wellbore stability. The approach described herein may provide an avenue for inhibiting both the surface hydration and the osmotic hydration of shale.
The occurrence and impacts of emerging organic contaminants (EOCs) in the aquatic environment have gained widespread attention over the past two decades. Due to large number of potential contaminants, monitoring campaigns, treatment plants, and proposed regulations should preferentially focus on specific pollutants with the highest potential for ecological and human health effects. In the present study, a multi-criteria screening approach based on hazard and exposure potentials was developed for prioritization of 405 unregulated EOCs already present in Chinese surface water. Hazard potential, exposure potential, and risk quotients for ecological and human health effects were quantitatively analyzed and used to screen contaminants. The hazard potential was defined by contaminant persistence, bioaccumulation, ecotoxicity, and human health effects; similarly, the exposure potential was a function of contaminant concentration and detection frequency. In total, 123 compounds passed the preselection process, which involved a priority index equal to the normalized hazard potential multiplied by the normalized exposure potential. Based on the prioritization scheme, 11 compounds were identified as top-priority, and 37 chemicals were defined as high-priority. The results obtained by the priority index were compared with four other prioritization schemes based on exposure potential, hazard potential, or risk quotients for ecological effects or human health. The priority index effectively captured and integrated the results from the more simplistic prioritization schemes. Based on identified data gaps, four uncertainty categories were classified to recommend: ① regular monitoring, derivation of environmental quality standards, and development of control strategies, ② increased monitoring, ③ fortified hazard assessment, and ④ increased efforts to collect occurrence and toxicity data. Overall, 20 pollutants were recommended as priority EOCs. The prioritized list of contaminants provides the necessary information for authoritative regulations to monitor, control, evaluate, and manage the risks of environmentally-relevant EOCs in Chinese surface water.
Despite their superior control performance, active vibration control techniques cannot be widely used in some engineering fields because of their substantial power demand in controlling large-scale structures. As an innovative solution to this problem, an unprecedented self-powered active vibration control system was established in this study. The topological design, working mechanism, and power flow of the proposed system are presented herein. The self-powering ability of the system was confirmed based on a detailed power flow analysis of vibration control processes. A self-powered actively controlled actuator was designed and applied to a scaled active vibration isolation table. The feasibility and effectiveness of the innovative system were successfully validated through a series of analytical, numerical, and experimental investigations. The setup and control strategy of the proposed system can be readily extended to diversified active vibration control applications in various engineering fields.
Carbapenem resistance presents a major challenge for the global public health network, as clinical infections caused by carbapenem-resistant organisms (CRO) are frequently associated with significant morbidity and mortality. Ceftazidime–avibactam (CAZ–AVI) is a novel cephalosporin/β-lactamase inhibitor combination offering an important advance in the treatment of CRO infections. CAZ–AVI has been reported to inhibit the activities of Ambler classes A, C, and some class D enzymes. However, bacterial resistance has been emerging shortly after the introduction of this combination in clinical use, with an increasing trend. Understanding these resistance mechanisms is crucial for guiding the development of novel treatments and aiding in the prediction of underlying resistance mechanisms. This review aims to systematically summarize the epidemiology of CAZ–AVI-resistant strains and recently identified resistance mechanisms of CAZ–AVI, with a focus on the production of β-lactamase variants, the hyperexpression of β-lactamases, reduced permeability, and overexpressed efflux pumps. The various mechanisms of CAZ–AVI resistance that have emerged within a short timescale emphasize the need to optimize the use of current agents, as well as the necessity for the surveillance of CAZ–AVI-resistant pathogens.
Since the 1990s, continuous technical and scientific advances have defied the diffraction limit in microscopy and enabled three-dimensional (3D) super-resolution imaging. An important milestone in this pursuit is the coherent utilization of two opposing objectives (4Pi geometry) and its combination with super-resolution microscopy. Herein, we review the recent progress in 4Pi nanoscopy, which provides a 3D, non-invasive, diffraction-unlimited, and isotropic resolution in transparent samples. This review includes both the targeted and stochastic switching modalities of 4Pi nanoscopy. The schematics, principles, applications, and future potential of 4Pi nanoscopy are discussed in detail.