From typical electrical appliances to thriving intelligent robots, the exchange of information between humans and machines has mainly relied on the contact sensor medium. However, this kind of ...contact interaction can cause severe problems, such as inevitable mechanical wear and cross‐infection of bacteria or viruses between the users, especially during the COVID‐19 pandemic. Therefore, revolutionary noncontact human–machine interaction (HMI) is highly desired in remote online detection and noncontact control systems. In this study, a flexible high‐sensitivity humidity sensor and array are presented, fabricated by anchoring multilayer graphene (MG) into electrospun polyamide (PA) 66. The sensor works in noncontact mode for asthma detection, via monitoring the respiration rate in real time, and remote alarm systems and provides touchless interfaces in medicine delivery for bedridden patients. The physical structure of the large specific surface area and the chemical structure of the abundant water‐absorbing functional groups of the PA66 nanofiber networks contribute to the high performance synergistically. This work can lead to a new era of noncontact HMI without the risk of contagiousness and provide a general and effective strategy for the development of smart electronics that require noncontact interaction.
Flexible noncontact sensing based on a high‐sensitivity humidity sensor is realized by anchoring multilayer graphene (MG) into electrospun polyamide (PA) 66 for human–machine interaction systems, which can achieve not only asthma detection, via monitoring the respiration rate in real time, and remote alarm systems, but also touchless interfaces in medicine delivery for bedridden patients.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Owing to the limitations of two-dimensional devices such as easily damaged and airtight characteristics in practical applications, flexible fiber electronics which can narrow the gap between devices ...and wearable applications due to their unique stitchable function have been attracting tremendous attention nowadays. Here, this paper introduced a simple strategy for fabricating the piezoelectric microfiber with a novel core-sheath structure by directly electrospinning the poly(vinydene fluoride-trifluoroethylene) (P(VDF-TrFE)) onto the flexible conductive wire. Precise control of the fiber diameter and thickness of P(VDF-TrFE) functional layer can be achieved. Specifically, this stitchable fiber exhibits high sensitivity of 60.82 mV/N and excellent durability of 15000 cycles under positive compression, and finite element method (FEM) was carried out cooperating with practical experiment to analyze the stress and electric field distribution of piezoelectric fibers under both positive compression and bending modes through COMSOL software. The flexible stitchable fiber can bear various complex, even severe deformations such as bending and knotting, enabling itself to be woven into textile and further generate power and response when subjected to external deformation, which is of significance for the portable and wearable electronics that are expected to be breathable and comfortable. This work also offers a general and effective solution for the flexible and wearable electronic devices.
Piezoelectric microfibers with a novel core-sheath structure were fabricated by directly electrospinning the P(VDF-TrFE) onto the flexible conductive wire. The flexible stitchable fiber exhibits high sensitivity of 60.82 mV/N and excellent durability of 15000 cycles and can narrow the gap between electronics and wearable applications. Display omitted
•An electrospinning core-sheath piezoelectric microfiber for self-powered stitchable sensor is proposed.•The piezoelectric microfiber can work under both positive compression and bending modes.•The stress and electric field distribution are analyzed by finite element method (FEM) through COMSOL software.•Detection for human motions by smart fibers incorporating textile is achieved.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Evaluated the effects of three bio-surfactants on VFA production.•VFAs was increased from 75 to about 300gCOD/gVSS using the bio-surfactants.•EEM fluorescence spectroscopy was used ...to characterize dissolved organic matters.•Sludge solubilization and hydrolysis were improved in various degrees.•Methanogenesis inhibition by rhamnolipid and degradation of saponin both led to VFAs.
The application of chemical surfactants in the production of volatile fatty acids (VFAs) during sludge anaerobic fermentation has drawn wide attentions. Compared with chemosynthetic surfactants, bio-surfactants are readily biodegradable and thus have a low negative impact on the environment. This paper studied the effects of three types of bio-surfactants (surfactin, rhamnolipid and saponin) on VFA production during sludge anaerobic fermentation. The release of nitrogen and phosphorus was also observed. Dissolution of organic matters, fluorescence spectra of filtrates, key enzyme activities, surface activity and biodegradation of the bio-surfactants were analyzed to reveal the mechanisms. The results indicated that VFA production was increased to approximately 4-fold versus the blank (75mgCOD/gVSS) using surfactin, rhamnolipid and saponin at the dosage of 0.05, 0.05, 0.10g/g DS, respectively. However, some differences existed in their mechanisms of improved acid production. Surfactin mainly increased the dissolution of organic matters to reach a high VFA accumulation. Rhamnolipid also enhanced the dissolution but inhibited the methanogenesis. In addition, its effects on microbial activities limited the further improvement of VFA production. Despite a lower surface activity than the other two bio-surfactants, saponin showed a similar improvement of VFA production through its self-degradation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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•Nanofibers based on BZT-BCT and P(VDF-TrFE) were successfully prepared through electrospinning method.•The nanofiber generator with 40% contents BZT-BCT exhibits more excellent ...output performance with the Voc of 13.01 V.•The generator is sensitive to the micro force and the Voc performs good linearty within the loading force.•The generator can response to different modes of deformation, even the small movements of human motion.
Recently, the flexible and environmental-friendly piezoelectric generators have drawn much attentions due to the power-supplying apply applications of powering implantable and wearable devices. In this work, an environmental-friendly and flexible piezoelectric nanogenerator is proposed based on electrospinning nanofiber which is composed of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT) and polyvinylidene fluoride–trifluoroethylene P(VDF-TrFE). The as-prepared nanofiber mats with different amounts of doping of BZT-BCT nanoparticles varied from 0 wt% to 50 wt% are characterized by XRD and SEM. Based on the testing results, the nanofiber generator with 40 % content of BZT-BCT exhibits the excellent output performance, which produces the output voltage as high as 13.01 V under cyclic tapping under 6 N and 10 Hz, which is mostly attributed from the doping of the BZT-BCT with high piezoelectric coefficient. The generator can be deployed as the self-powered sensor, which can measure the tensile and compressive deformation, the movement of different parts of body. Due to the advantages of flexibility and environmental kindness, this developed nanogenerator has great potential for wearable and implantable devices.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Flexible wearable sensors have received considerable popularity due to their potential application in monitoring human activities and health conditions. However, traditional pressure sensors always ...rely on a single mechanism (such as piezoelectric or piezoresistive effect), which shows great limitation in the cooperative monitoring of static and highly dynamic pressure detection and severely restricts their further practical applications. Herein, a new strategy of combining piezoelectric and piezoresistive mechanisms in one single flexible sensor is reported for the realization of dual function detection. In detail, a piezoelectric unit (non-array and array) based on a flexible poly(vinylidene fluoride) (PVDF) polymer is deployed for highly dynamic detection, while the composite of graphite sheet (GS)-decorated PVDF electrospun mat composite serves as a piezoresistive unit for static detection. The device exhibits excellent piezoresistive durability (over 600 cycles) and higher piezoelectric sensitivity of 0.5 N V
−1
at the applied frequency of 5 Hz due to the fact that the introduction of a soft piezoresistive layer increases the transverse strain on the piezoelectric layer originating from large deformation of the low stiffness surface. On the basis of the collaborative and complementary advantages, accurate and reliable detection of human motions such as elbow and heel activities are realized, indicating great potential in wearable electronics applications from zero to high frequency. This study provides general guidance for the development of flexible pressure sensors that require dynamic and static cooperative detection capabilities.
A dual-function flexible sensor is prepared by coupling piezoresistive and piezoelectric mechanisms for the simultaneous detection of highly dynamic and static behavior and used to effectively detect body movements, such as elbow and heel motions.
Recently, utilizing CO2 as a methylation reagent to construct functional chemicals has attracted significant attention. However, the conversion of CO2 is still a challenge due to its inherent ...inertness. In this study, we have developed a catalyst-free N-methylation of amines to prepare numerous methylamines using CO2 as a methyl source. By utilizing 2 eq. PhSiH3 as the reductant, amines could undergo N-methylation under 1 atm of CO2 in DMF at 90 °C. Aliphatic and aromatic amines were compatible, generating the desired products in up to 95% yield.
Cheap and widely available carboxylic acids are a class of ideal substrates to construct valuable compounds. As a candidate of decarboxylative reactions, the acid-based neutral N-hydroxyphthalimide ...ester undergoes a reductive decarboxylative process rather than a common oxidative decarboxylative process, which is a potential transformation mode for new reactions. In this work, we developed an electrochemical C(sp
)-C(sp
) coupling of N-hydroxyphthalimide esters and N-heteroarenes without any catalysts. Remarkably, this electrochemical protocol can not only be directly realised by carboxylic acids in a one-pot fashion, but also be scaled up using a continuous-flow reactor.
Heterocycles containing N and O are important structures in pharmaceuticals, agrochemicals and functional molecules. The synthesis of these compounds usually requires complex substrates and harsh ...reaction conditions. Herein, we introduce a mild and efficient electrochemical oxidative strategy to construct benzoxazines, oxazolines and iminoisobenzofurans without the requirement of a transition-metal catalyst and an external oxidant. In a simple undivided cell, various olefinic amides and thiophenols/diselenides react to generate 69 examples of thiolation and selenylation heterocycles in up to 83% yields. Furthermore, this radical cascade reaction provided a facile method for constructing C-S/C-Se and C-O bonds in one step.
Heterocycles containing N and O are important structures in pharmaceuticals, agrochemicals and functional molecules.
Transitions: The title reaction has been developed for the synthesis of a variety of tert‐butyl benzoates by employing 1,10‐phenanthroline as an additive. Various functional groups were tolerated and ...heteroaryl iodides were also suitable substrates. Preliminary mechanism studies were conducted and indicate the participation of radical intermediates.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Background
Extant research has indicated that parenting practice, such as harsh parenting, rejection, and neglect increases the risk of mobile phone addiction. However, no research to date has ...examined the association between parenting by lying about money and adolescent mobile phone addiction.
Objective
The current study used a survey to test whether parenting by lying about money may be associated with adolescent mobile phone addiction. The mediation of anxiety and moderation of socioeconomic status were also examined.
Materials and methods
We recruited 971 adolescents from five secondary schools in a city in central China. Of the participants, 448 (46.14%) were boys and 523 (53.86%) were girls (
M
age
= 13.63,
SD
age
= 1.01).
Results
The results of mediation analysis indicated that parenting by lying about money positively predicted mobile phone addiction (
B
= 0.144,
p
< 0.01); parenting by lying about money positively predicted anxiety (
B
= 0.126,
p
< 0.01) and mobile phone addiction (
B
= 0.107,
p
< 0.01). Anxiety positively predicted mobile phone addiction (
B
= 0.293,
p
< 0.01). Moreover, the bias-corrected bootstrapping mediation test indicated that the process by which parenting by lying about money predicted mobile phone addiction through anxiety was significant (indirect effect = 0.037,
SE
= 0.011, 95% CI = 0.017, 0.059).
Conclusion
The current study suggests that parenting by lying about money may lead to mobile phone addiction through the mediation of anxiety. However, the effect was stronger for adolescents with higher level of socioeconomic status than their counterparts.
