3D Printed MXene-Based Wire Strain Sensors with Enhanced Sensitivity and Anisotropy.

Stretchable strain sensors play a crucial role in intelligent wearable systems, serving as the interface between humans and environment by translating mechanical strains into electrical signals. Traditional fiber strain sensors with intrinsic uniform axial strain distribution face challenges in achieving high sensitivity and anisotropy. Moreover, existing micro/nano-structure designs often compromise stretchability and durability. To address these challenges, a novel approach of using 3D printing to fabricate MXene-based flexible sensors with tunable micro and macrostructures.  Poly(tetrafluoroethylene) (PTFE) as a pore-inducing agent is added into 3D printable inks to achieve controllable microstructural modifications. In addition to microstructure tuning, 3D printing is employed for macrostructural design modifications, guided by finite element modeling (FEM) simulations. As a result, the 3D printed sensors exhibit heightened sensitivity and anisotropy, making them suitable for tracking static and dynamic displacement changes. The proposed approach presents an efficient and economically viable solution for standardized large-scale production of advanced wire strain sensors.

Pulse-shaped high-energy and high-average-power fiber laser in the nanosecond regime.

A high-energy and high-average-power pulsed fiber laser has been investigated in a master oscillator power amplifier (MOPA) configuration seeding with a diode laser at a programmed pulse duration of ∼250ns. The fiber amplifier successfully demonstrates the pulse with 21.4 mJ at the repetition rate of 50 kHz and a maximum average output power of 1535 W with a slope efficiency of 81.6% at 250 kHz. To overcome fiber nonlinearities such as stimulated Raman scattering (SRS) and self-phase modulation (SPM), extra-large mode area ytterbium (Yb)-doped step-index dual cladding fiber has been utilized as gain fiber in the MOPA laser system. The gain saturation effect in the power amplifier was greatly mitigated by the programmed seed signal. This pulse-shaped MOPA system can provide practical applications in many fields such as laser cleaning, paint stripping, and other applications requiring special pulse shapes.

Urea impregnation into fungus pretreated corn stover to perform pyrolysis for production of nitrogen-containing bio-oil and nitrogen-doped biochar.

Urea was introduced into the fungal pretreated corn stover and then the urea soaked materials were subjected to pyrolysis for the production of nitrogen-containing bio-oil and nitrogen-doped biochar. The urea soaking effectively realized the enrichment of nitrogen-containing compounds in the bio-oil and the maximal content of the nitrogen-containing compounds in bio-oils reached up to 66.32% under 4 wt% urea concentration. Among the nitrogen-containing compounds, amines were the most dominant component with the maximal content of 41.17%. The higher urea concentration is beneficial to make more nitrogen be fixed in the biochar. The nitrogen content of the biochar reached up to 12.86 wt% under 8 wt% urea concentration. Nitrogen on the biochar surface existed in the form of pyrrolic-N, pyridinic-N and graphite-N. In conclusion, urea simple soak on fungus pretreated biomass to perform pyrolysis is a promising approach to obtain high value-added nitrogen-containing chemicals and nitrogen-doped biochar with high nitrogen content.

Influence of Water on Gel Electrolytes for Zinc-Ion Batteries.

Gel electrolytes are being intensively explored for aqueous rechargeable zinc-ion batteries, especially towards high performance and multi-functionalities. Water plays a central role on the fundamental properties, interface reaction/interaction, and performance of the gel-type zinc electrolyte. In this review, the influence of water on the physiochemical properties of gel electrolytes is focused on. The correlation between water activity and the fundamental properties of zinc electrolytes is presented. Current approaches and challenges in manipulating water activity and the consequent influence on the electrochemical stability, transport, and interface kinetics of gel electrolytes are summarized. An outlook on approaches to tuning and investigating water activity is provided to shed light on the design of advanced gel electrolytes.

Effect of pretreatment with Phanerochaete chrysosporium on physicochemical properties and pyrolysis behaviors of corn stover.

Fungal pretreatment can selectively degrade partial biomass components, which undoubtedly exerts a significant influence on biomass pyrolysis behavior. The corn stover was pretreated with Phanerochaete chrysosporium, and its influence on the physicochemical properties and pyrolysis behaviors of biomass together with the product characteristics were investigated. The Phanerochaete chrysosporium was more active to degrade hemicellulose and lignin. The hemicellulose and lignin contents in corn stover were decreased by 35.14 % and 31.80 %, respectively, after five weeks pretreatment, compared to the untreated sample. The reaction activation energy decreased from 52.89 kJ·mol-1 for the untreated sample to 40.88 kJ·mol-1 for the sample pretreated for five weeks. The Phanerochaete chrysosporium pretreatment was beneficial to the biochar production but exerted an unfavorable effect on the texture structure. The Phanerochaete chrysosporium also had an obvious influence on the bio-oil compositions. This study can provide a scientific reference for the application of biological pretreatment for biomass pyrolysis technology.

Accuracy improvement of quantitative LIBS analysis of coal properties using a hybrid model based on a wavelet threshold de-noising and feature selection method.

A hybrid model based on a wavelet threshold de-noising (WTD) and recursive feature elimination with cross-validation (RFECV) method was proposed to improve the measurements in quantitative analysis of coal properties using laser-induced breakdown spectroscopy (LIBS). First, a modified threshold of WTD was proposed based on wavelet coefficient theory. Interference of noise in the LIBS spectrum was reduced by using this modified method. Then, the RFECV method was applied to extract effective features from the de-noised LIBS spectrum. Finally, support vector regression (SVR) models of coal properties were established by the selected features. A validation set was used to verify the effectiveness and robustness of the hybrid model. The improvement of the hybrid model on the quantitative analysis of each index of coal properties (heat value, ash, volatile content) was studied and discussed. By using the proposed model, the determination coefficient (R2), root mean square error of prediction, average relative error, and relative standard deviation were all significantly improved over the original spectra model. The results demonstrated that the proposed model could effectively improve the accuracy and precision of LIBS quantitative analysis for coal properties.

Quantitative phase imaging based on simple Michelson-type lateral shearing interferometry with rotational right-angle prisms.

By using a kind of simple Michelson-type lateral shearing interferometry, in this paper, the precise quantitative phase measurement of transparent microscopic objects is realized successfully. For this interferometry, on the basis of the fundamental structure of the traditional Michelson interferometer, the two plane mirrors are replaced with two ordinary right-angle prisms. In the beginning, the ridges of the two right-angle prisms are set to align with the optical axis and be in the vertical direction. Subsequently, to achieve the lateral shear, one of these two right-angle prisms is rotated around its ridge. Furthermore, the goal to obtain more lateral shear can be achieved by introducing a bigger rotating angle or rotating another prism simultaneously. In addition, owing to the simple structure of the Michelson interferometer and the inexpensive optical components used, the system is compact, portable, easy to operate, and low cost. The experimental results show the practicability of this system.