Recently, sensors that can imitate human skin have received extensive attention. Capacitive sensors have a simple structure, low loss, no temperature drift, and other excellent properties, and can be ...applied in the fields of robotics, human–machine interactions, medical care, and health monitoring. Polymer matrices are commonly employed in flexible capacitive sensors because of their high flexibility. However, their volume is almost unchanged when pressure is applied, and they are inherently viscoelastic. These shortcomings severely lead to high hysteresis and limit the improvement in sensitivity. Therefore, considerable efforts have been applied to improve the sensing performance by designing different microstructures of materials. Herein, two types of sensors based on the applied forces are discussed, including pressure sensors and strain sensors. Currently, five types of microstructures are commonly used in pressure sensors, while four are used in strain sensors. The advantages, disadvantages, and practical values of the different structures are systematically elaborated. Finally, future perspectives of microstructures for capacitive sensors are discussed, with the aim of providing a guide for designing advanced flexible and stretchable capacitive sensors via ingenious human‐made microstructures.
The advantages, disadvantages, and practical applications of several popular microstructures that are widely employed in capacitive sensors are summarized. A microstructured dielectric layer or electrode can improve sensor sensitivity, reduce hysteresis, and endow the rigid electronic device with excellent elastic stretchability, which is an essential part of next‐generation wearable devices and soft robots.
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.
A Ka -band wideband dual-polarized magnetoelectric (ME) dipole antenna with the feeding structure consisting of two orthogonal L-shaped probes with different heights is presented based on the ...low-temperature cofired ceramic (LTCC) technology. A simulated overlapped impedance bandwidth of 42.5% is achieved together with an isolation of higher than 24 dB between the two input ports and stable radiation characteristics over the operating band. By combining the radiating elements with a single-layered feed network composed of microstrip lines, a <inline-formula> <tex-math notation="LaTeX">4\times 4 </tex-math></inline-formula> dual-polarized ME dipole antenna array is designed, fabricated, and measured. An overlapped impedance bandwidth of 45% that can cover the entire Ka -band, a gain up to 16.1 dBi, and stable symmetrical radiation patterns in the two orthogonal planes with cross polarization of less than −15 dB are experimentally confirmed. With advantages of the compact geometry, wide operating band, and promising radiation performance, the proposed antenna array with dual polarization would be attractive for millimeter-wave wireless applications in Ka -band.
•Introduced the antimicrobial activities of SEOs and their main active components.•SEOs are potential substitute for chemical preservatives.•Summarized the antimicrobial mechanism of SEOs and their ...main components.•SEOs can be used for active packaging to prevent food spoilage in the food industry.
Spice essential oils (SEOs) are commonly used in food flavoring and are considered an effective food preservative. It has a broad range of applications and promising development prospects. As a natural food additive, SEOs’ antimicrobial effects have been widely studied and utilized towards food preservation. Many SEOs have exhibited significant antimicrobial activities against food-borne pathogenic and food spoilage microorganisms. We reviewed the antibacterial and antifungal properties of SEOs, the active components, their corresponding mechanisms of actions, as well as their application in the food industry, providing a theoretical basis for SEOs’ further development and application as natural preservatives.
The transmission of infectious diseases has been studied by mathematical methods since 1760s, among which SIR model shows its advantage in its epidemiological description of spread mechanisms. Here ...we established a modified SIR model with nonlinear incidence and recovery rates, to understand the influence by any government intervention and hospitalization condition variation in the spread of diseases. By analyzing the existence and stability of the equilibria, we found that the basic reproduction number Formula: see text is not a threshold parameter, and our model undergoes backward bifurcation when there is limited number of hospital beds. When the saturated coefficient a is set to zero, it is discovered that the model undergoes the Saddle-Node bifurcation, Hopf bifurcation, and Bogdanov-Takens bifurcation of codimension 2. The bifurcation diagram can further be drawn near the cusp type of the Bogdanov-Takens bifurcation of codimension 3 by numerical simulation. We also found a critical value of the hospital beds bc at Formula: see text and sufficiently small a, which suggests that the disease can be eliminated at the hospitals where the number of beds is larger than bc. The same dynamic behaviors exist even when a ≠ 0. Therefore, it can be concluded that a sufficient number of the beds is critical to control the epidemic.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
High‐energy‐density lithium (Li) metal batteries suffer from a short lifespan owing to apparently ceaseless inactive Li accumulation, which is accompanied by the consumption of electrolyte and active ...Li reservoir, seriously deteriorating the cyclability of batteries. Herein, a triiodide/iodide (I3−/I−) redox couple initiated by stannic iodide (SnI4) is demonstrated to reclaim inactive Li. The reduction of I3− converts inactive Li into soluble LiI, which then diffuses to the cathode side. The oxidation of LiI by the delithiated cathode transforms cathode into the lithiation state and regenerates I3−, reclaiming Li ion from inactive Li. The regenerated I3− engages the further redox reactions. Furthermore, the formation of Sn mitigates the corrosion of I3− on active Li reservoir sacrificially. In working Li | LiNi0.5Co0.2Mn0.3O2 batteries, the accumulated inactive Li is significantly reclaimed by the reversible I3−/I− redox couple, improving the lifespan of batteries by twice. This work initiates a creative solution to reclaim inactive Li for prolonging the lifespan of practical Li metal batteries.
A triiodide/iodide (I3−/I−) redox couple is introduced with a SnI4 initiator to reclaim inactive Li. The reduction of I3− converts inactive Li into soluble LiI, and the oxidation of LiI by a delithiated cathode realizes the restoration of Li ion in cathode from inactive Li. The regenerated I3− by oxidation engages the further redox reactions.
Recent big data analyses have illuminated marine microbial diversity from a global perspective, focusing on planktonic microorganisms. Here, we analyze 2.5 terabases of newly sequenced datasets and ...the Tara Oceans metagenomes to study the diversity of biofilm-forming marine microorganisms. We identify more than 7,300 biofilm-forming 'species' that are undetected in seawater analyses, increasing the known microbial diversity in the oceans by more than 20%, and provide evidence for differentiation across oceanic niches. Generation of a gene distribution profile reveals a functional core across the biofilms, comprised of genes from a variety of microbial phyla that may play roles in stress responses and microbe-microbe interactions. Analysis of 479 genomes reconstructed from the biofilm metagenomes reveals novel biosynthetic gene clusters and CRISPR-Cas systems. Our data highlight the previously underestimated ocean microbial diversity, and allow mining novel microbial lineages and gene resources.
An orientation insensitive antenna is proposed for the 2.4-GHz industrial, scientific, and medical band wireless capsule endoscopy system. To achieve the polarization diversity, three orthogonal ...currents are obtained by bending a dipole. Inversed T matching branch and meander lines are employed to gain better impendence matching and miniaturization. A normal dipole in capsule with single polarization is set as the reference antenna in simulation. The one-layer muscle phantom and the Gustav human body model are adopted in simulation. Minced pork is used during measurement. Communication links between the proposed capsule antenna and the external receiving antenna when they are in different orientations are measured to demonstrate the advantages the polarization diversity brings. According to the measured |S21|, the proposed antenna can transmit effectively even the orientation of the capsule is changed; therefore, direction insensitivity performance is achieved.
The worldwide prevalence of infections caused by antibiotic-resistant Gram-negative bacteria poses a serious threat to public health due to the limited therapeutic alternatives. Cationic peptides ...represent a large family of antibiotics and have attracted interest due to their diverse chemical structures and potential for combating drug-resistant Gram-negative pathogens. Here, we analyze 7395 bacterial genomes to investigate their capacity for biosynthesis of cationic nonribosomal peptides with activity against Gram-negative bacteria. Applying this approach, we identify two novel compounds (brevicidine and laterocidine) showing bactericidal activities against antibiotic-resistant Gram-negative pathogens, such as Pseudomonas aeruginosa and colistin-resistant Escherichia coli, and an apparently low risk of resistance. The two peptides show efficacy against E. coli in a mouse thigh infection model. These findings may contribute to the discovery and development of Gram-negative antibiotics.
Recently, the recurrence of positive SARS-CoV-2 viral RNA in recovered COVID-19 patients is receiving more attention. Herein we report a cohort study on the follow-up of 182 recovered patients under ...medical isolation observation. Twenty (10.99%) patients out of the 182 were detected to be SARS-CoV-2 RNA positive (re-positives), although none showed any clinical symptomatic recurrence, indicating that COVID-19 responds well to treatment. Patients aged under 18 years had higher re-positive rates than average, and none of the severely ill patients re-tested positive. There were no significant differences in sex between re-positives and non-re-positives. Notably, most of the re-positives turned negative in the following tests, and all of them carried antibodies against SARS-CoV-2. This indicates that they might not be infectious, although it is still important to perform regular SARS-CoV-2 RNA testing and follow-up for assessment of infectivity. The findings of this study provide information for improving the management of recovered patients, and for differentiating the follow-up of recovered patients with different risk levels.
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