Semiconductor quantum dots (QDs) are competitive emitting materials in developing new-generation light-emitting diodes (LEDs) with high color rendering and broad color gamut. However, the use of ...highly toxic alkylphosphines cannot be fully avoided in the synthesis of metal selenide and telluride QDs because they are requisite reducing agents and solvents for preparing chalcogen precursors. In this work, we demonstrate the phosphine-free preparation of selenium (Se) and tellurium (Te) precursors by directly dissolving chalcogen dioxides in the alkylthiol under the mild condition. The chalcogen dioxides are reduced to elemental chalcogen clusters, while the alkylthiol is oxidized to disulfides. The chalcogen clusters further combine with the disulfides, generating dispersible chalcogen precursors. The resulting chalcogen precursors are suitable for synthesizing various metal chalcogenide QDs, including CdSe, CdTe, Cu2Te, Ag2Te, PbTe, HgTe, and so forth. In addition, the precursors are of high reactivity, which permits a shorter QD synthesis process at lower temperature. Owing to the high quantum yield (QYs) and easy tunability of the photoluminescence (PL), the as-synthesized QDs are further employed as down-conversion materials to fabricate monochrome and white LEDs.
The development of fiber materials has accompanied the evolution of human civilization for centuries. Recent advances in materials science and chemistry offered fibers new applications with various ...functions, including energy harvesting, energy storing, displaying, health monitoring and treating, and computing. The unique one-dimensional shape of fiber devices endows them advantages to work as human-interfaced electronics due to the small size, lightweight, flexibility, and feasibility for integration into large-scale textile systems. In this review, we first present a discussion of the basics of fiber materials and the design principles of fiber devices, followed by a comprehensive analysis on recently developed fiber devices. Finally, we provide the current challenges facing this field and give an outlook on future research directions. With novel fiber devices and new applications continuing to be discovered after two decades of research, we envision that new fiber devices could have an important impact on our life in the near future.
Responsive Polymer Composite Fiber Feng, Jianyou; Peng, Huisheng
Chinese journal of chemistry,
15 July 2022, Letnik:
40, Številka:
14
Journal Article
Recenzirano
Comprehensive Summary
Wearable devices are a mainstream for our future daily life, where responsive polymer composite fibers represent one of the key components. However, their practical applications ...are hampered by several challenges, including poor responsive reversibility, poor controllability and low stability as well as single function. Herein, we share our recent studies on overcoming the above challenges for achieving novel responsive polymer composite fibers, especially focusing on chromatic fibers, deformational fibers and their integrations. Furthermore, we introduce a type of novel materials for these responsive fiber materials, i.e., aligned carbon nanotube sheets and fibers simultaneously with excellent electrical, optical and mechanical properties. For the future development, we further highlight the possible directions in this field.
What is the most favorite and original chemistry developed in your research group?
The conception and realization of display textile. Displays are the basic building blocks of electronics. Integrating displays into textiles offers exciting opportunities for smart electronic textiles, which are believed to change the future life of the human being. For instance, display textiles serve to bridge human‐machine interactions, and a real‐time communication tool may become true for individuals with voice or speech disorders. After hard work for over ten years, we have finally achieved this goal at lab and further produced such display textiles at large scale at industry.
How do you get into this specific field? Could you please share some experiences with our readers?
When I started to do research independently at Fudan University, I tried to do something unique. I just did not hope to simply follow the available direction. I majored at chemical fibers during my undergraduate study and later made research on electronic devices, so it was natural for me to combine fibers and electronics together. I do not remember the detail time I figured out the idea. In my mind, it should be very interesting and must be very cool. I did not know and even had not thought whether they were useful or not. After the paper was published in 2021, so many people contacted us for the use of display textiles for a spectrum of applications. During the study on the display textiles that have been also investigated for smart systems, we started to explore new smart fiber
materials almost at the same time. These smart fiber materials are discussed in this article.
How do you supervise your students?
First, it is important for me to understand them as every student is unique. Second, according to their characteristics, I may choose specific research projects, often following their interests. Third, I fully respect them when they start the research. They are totally free to decide the work time and work style. I trace the process mainly aiming at solving problems for them. Of course, I keep asking them to enhance their scientific tastes and make the first‐class research, not only so‐called original science or technology. I will try my best to help them to publish their results at top journals, which is important for their future development. During the whole training process, the most important thing I hope to achieve is enjoying science, at least feel successful. It is obviously not easy. Sometimes we make it, and sometimes we fail. We always work for the better full of hope. I sincerely hope that every student, after graduation, will have a good memory at my lab.
What is the most important personality for scientific research?
I think there are two very important characteristics. One is brave. A scientist should be brave to solve the most difficult problem in the field. The other is imagination. Science is pretty similar to arts in many aspects. We may fix the gap sometimes through imagination. However, it is particularly challenging to train scientists for good imagination in science.
This review article summarizes the recent progress on responsive polymer composite fibers, with a focus on chromatic and deformational fibers.
Research on fatigue behavior and microstructural evolution of P91 steel under pre-dynamic strain aging conditions (pre-DSA), and strain aging (SA) conditions at 550 °C has been carried out, and the ...experimental results were compared with the pure fatigue (PF) results, also at 550 °C. The comparison indicated that, under various strain amplitudes, the fatigue life of P91 at 550 °C decreased after pre-DSA or SA treatments relative to PF, and that the effect of the pre-DSA treatment was more significant. The SA treatment induced the localization of plastic deformation, creating obvious stress concentrations on the surface that led to the initiation of multiple cracks which decreased the fatigue life of P91. Transmission electron microscopy analysis of P91 indicated that pre-DSA promoted higher dislocation density and increased the mechanical strength, while SA decreased the dislocation density and the mechanical strength. During fatigue tests, the martensite laths in pre-DSA and SA specimens recovered more completely relative to those under PF, and the recovery extent was directly related with the decrease of fatigue life.
Two sided laser shock processing (TSLSP) is often employed to improve the surface quality of thin section components, which can reduce excessive plastic deformation induced by one sided laser shock ...processing. Residual stresses (RS) field induced in a thin Ti–6Al–4V alloy plate by TSLSP was investigated through numerical simulation and experiments. The effects of key parameters, viz., metal plate thickness, shock wave pressure and number of laser shocks, on RS field were analyzed. The simulation results show that the RS field induced by TSLSP was distributed symmetrically in the metal plate. For thin sections, compressive residual stresses (CRS) were found to exist on the surface of both the sides and also in the mid-plane region, whereas, for thick sections, CRS were found to only distribute on the surface of both the sides. The multiple TSLSP impacts and the increasing laser shock pressure were found to have significant effects on the RS field. The RS values predicted by the model correlated well with the experimental data.
•The mechanism of two-sided laser shock processing (TSLSP) was described.•The propagation, attenuation, and collision of stress waves were analyzed in detail.•Compressive residual stresses (CRS) were found on both surfaces after TSLSP.•CRS were also found to appear at the mid-plane region of thinner plates after TSLSP.•The CRS in material had a characteristic of saturation in TSLSP treatment.
Electrophysiology and neurochemicals such as Ca2+, K+, and Na+ on the cerebral cortex can synergistically reflect the neurophysiological states. Transparent electrodes have been reported to record ...electrocorticography (ECoG) and image Ca2+ on the cerebral cortex surface. However, Ca2+ imaging is unable to track extracellular changes correlated with neural activities such as anesthesia, and imaging techniques to monitor K+ and Na+ are yet unavailable. Here, a flexible multifunctional electrode (FME) based on carbon nanotube array is presented to record ECoG and extracellular ions of Ca2+, K+, and Na+. The FME exhibits both lower impedance and higher capacitance than that of conventional gold electrodes. It simultaneously shows stable ion‐sensing performance and long‐term biocompatibility. The FME realizes multi‐model recording of ECoG and extracellular ions on the cerebral cortex surface of rats, providing an effective detection method for brain science.
A carbon nanotube array‐based flexible film device is designed with integration of electrocorticography and ion‐selective electrodes for high detection performances. It exhibits low impedance, high capacitance, and stable ion‐sensing performance, simultaneously realizing record of electrophysiology and detection of extracellular Ca2+, K+, and Na+ in vivo for 2 weeks.
Continuous and precise monitoring of chemicals in the brain can assist in understanding the working mechanism of the brain and exploring therapeutics for nerve disorders. Organic electrochemical ...transistors (OECTs) are employed for this purpose due to their high sensitivity from the in situ amplification effect. However, the chronic and stable detection of chemicals in the brain is rarely reported for OECTs. It is possibly due to the chronic inflammation from mechanical mismatch between the device and soft brain tissue as well as the biofouling that hinder the diffusion of chemicals to decrease the sensitivity similar to other implanted devices. Therefore, an all‐polymer fiber OECT (PF‐OECT) is designed, composed solely of conductive polymers and fluorine rubber. The PF‐OECT shows matching modulus with the soft brain tissue and good anti‐biofouling performance. It also demonstrates both high sensitivity and electrochemical stability under dynamic deformations and in complex protein solutions. Finally, the PF‐OECT is implanted into the mouse brain, achieving a stable 14‐day ascorbic acid monitoring. The design strategy of PF‐OECT presents a potential avenue for developing more biomedical devices.
An all‐polymer fiber organic electrochemical transistor is designed with conducting polymer fiber as channel and electrodes insulated with fluorine rubber. It exhibits high sensitivity, matched modulus with soft brain tissue, good anti‐biofouling performance and biocompatibility, realizing stable detection of ascorbic acid for 14 days in vivo.
Fiber organic electrochemical transistors (OECTs) have received extensive attention in wearable and implantable biosensors because of their high flexibility and low working voltage. However, the ...transconductance of fiber OECTs is much lower compared with the planar counterparts, leading to low sensitivity. Here, we developed fiber OECTs in a coaxial configuration with microscale channel length to achieve the highest transconductance of 135 mS, which is one to two orders of magnitude higher than that of the state-of-the-art fiber OECTs. Coaxial fiber OECT based sensors showed high sensitivities of 12.78, 20.53 and 3.78 mA/decade to ascorbic acid, hydrogen peroxide and glucose, respectively. These fiber OECTs were woven into a fabric to monitor the glucose in sweat during exercise and implanted in mouse brain to detect ascorbic acid. This coaxial architectural design offers an effective way to promote the performance of fiber OECTs and realize highly sensitive detection of biochemicals.
An analytical solution is presented for the axisymmetric static responses of thick functionally graded (FGM) cylindrical shells with general boundary conditions, which strictly satisfies the boundary ...conditions along the thickness. The illustrative examples show that the presented solution of thick cylindrical shells under various boundary conditions is of high precision and good convergence. The exact distributions of displacement and stress components along the radial and axial directions are revealed, and the influences of thickness-to-radius ratio, span-to-radius ratio and material gradient index on the static responses of the thick FGM cylindrical shell are analyzed.
Long-term in vivo monitoring of chemicals with implanted sensors has received considerable interests over the past decades owing to their significant contributions in reflecting health conditions and ...assistance in diagnosing diseases. However, the widely explored chemical sensors outside the body fail to meet the requirements of in vivo applications. This perspective reviews main challenges, recent advances and future directions of long-term in vivo monitoring of chemicals, related to immune response and sensing performance. Challenges in terms of the immune response caused by unstable interfaces between sensors and tissues and improper implanting methods, and the insufficient performance of chemical sensors in complex physiological environment are discussed. Therewith, recent advances in fabricating biocompatible, flexible and thin sensors, developing effective implanting methods with reduced injury and improving the sensitivity, selectivity and stability of chemical sensors for accurate monitoring in vivo are summarized. Finally, we propose the future directions to address these challenges by fiber chemical sensors through the combination of soft fiber configuration, facile implanting methods and new recognition elements, which will provide new platforms for health monitoring and physiological mechanism revealing.
