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Heat dissipation problem is the primary factor restricting the service life of an electronic component. The thermal conductivity of materials has become a bottleneck that hinders the development of the electronic information industry (such as light-emitting diodes, 5G mobile phones). Therefore, the research on improving the thermal conductivity of materials has a very important theoretical value and a practical application value. Whether the thermally conductive filler in polymer composites can form a highly thermal conductive pathway is a key issue at this stage. The carbon fiber/carbon felt (CF/C felt) prepared in the study has a three-dimensional continuous network structure. The nickel-coated carbon fiber/carbon felt (CF/C/Ni felt) was fabricated by an electroplating deposition method. Three-dimensional CF/C/Ni/epoxy composites were manufactured by vacuum-assisted liquid-phase impregnation. By forming connection points between the adjacent carbon fibers, the thermal conduction path inside the felt can be improved so as to improve the thermal conductivity of the CF/C/Ni/epoxy composite. The thermal conductivity of the CF/C/Ni/epoxy composite (in-plane K∥) is up to 2.13 W/(m K) with 14.0 wt % CF/C and 3.70 wt % Ni particles (60 min electroplating deposition). This paper provides a theoretical basis for the development of high thermal conductivity and high-performance composite materials urgently needed in industrial production and high-tech fields.

Doping of metals is highly effective in improving electrochemical performance of lithium iron phosphate. Here, based on a first-principles calculation result that Ru doping at the Fe sites has positive effects on promoting the ability of electron and Li+ transmission by reducing the lattice parameter and band gap, as well as the increase in Fermi energy, we constructed Ru-doped LiFe1-x Ru x PO4/C through the sol-gel preparation technology as cathode materials for Li-ion batteries. As a result, LFP-1 (x = 0.01) delivers excellent specific capacities of 162.6 and 110.6 mA h g-1 under 0.1 and 10 C, respectively. At the same time, LFP-1 emerges with excellent cycling performance, with a capacity retention of up to 95.6% after 300 cycles at 5 C. Ru doping is beneficial for improving the lithium diffusion coefficient and electrical conductivity, therefore strongly increasing electrochemical performance. This work represents a significant addition to exploring a new class of lithium iron phosphates with excellent performance in new energy storage and transition systems.

In this work, a diffusion-theory-based model has been devised to simulate dissolution kinetics of a poorly water-soluble drug, ibuprofen. The model was developed from the Noyes-Whitney equation in which the dissolution rate term is a function of the remaining particulate surface area and the concentration gradient across the boundary layer. Other dissolution parameters include initial particle size, diffusion coefficient, material density, and diffusion boundary layer thickness. It is useful for predicting nonsink circumstances under which pure API polydisperse powders are suspended in a well-mixing tank. The model was used to compare the accuracy of simulations using spherical (single dimensional characteristic length) and cylindrical particle (multidimensional characteristic lengths) geometries, with and without size-dependent diffusion layer thickness. Experimental data was fitted to the model to obtain the diffusion layer thickness as well as used for model validation and prediction. The CSDs of postdissolution were also predicted with this model, demonstrating good agreement between theory and experiment.

Complex patterns integral to the structure and function of biological materials arise spontaneously during morphogenesis. In contrast, functional patterns in synthetic materials are typically created through multistep manufacturing processes, limiting accessibility to spatially varying materials systems. Here, we harness rapid reaction-thermal transport during frontal polymerization to drive the emergence of spatially varying patterns during the synthesis of engineering polymers. Tuning of the reaction kinetics and thermal transport enables internal feedback control over thermal gradients to spontaneously pattern morphological, chemical, optical, and mechanical properties of structural materials. We achieve patterned regions with two orders of magnitude change in modulus in poly(cyclooctadiene) and 20 °C change in glass transition temperature in poly(dicyclopentadiene). Our results suggest a facile route to patterned structural materials with complex microstructures without the need for masks, molds, or printers utilized in conventional manufacturing. Moreover, we envision that more sophisticated control of reaction-transport driven fronts may enable spontaneous growth of structures and patterns in synthetic materials, inaccessible by traditional manufacturing approaches., Competition between reaction and thermal transport during frontal polymerization drives the emergence of complex thermal profiles that are harnessed to spontaneously pattern material properties.

An organic ester p-nitrobenzyl acetate (PNBA) was synthesized and used to establish a kind of autogenic acid system through the hydrolysis of ester to acetic acid in situ. The autogenic acid system can form a homogeneous solution by adding an organic solvent. The autogenic acid system possesses the desired characteristic in which hydrolysis can generate a small amount of acetic acid below 120 °C and a large amount of acid above 140 °C in 2 h. The acid-generated ability at different time and temperature was studied in detail. The dissolution of solid calcium carbonate and carbonate rocks by the autogenic acid system was investigated. The autogenic acid displayed lower dissolution ability on a carbonate rock and weak corrosion of a N80 steel sheet at 150 °C. The autogenic acid is especially suitable for acid fracturing and dissolution of rocks in a high-temperature carbonate reservoir.

What are the risks associated with cryopreserved semen collected during and after the coronavirus disease 2019 (COVID-19) pandemic wave in Wuhan, China?Retrospective cohort study involving young adult men who were qualified sperm donors at the Hunan Province Human Sperm Bank (China) during the pandemic wave (1 January 2020 to 30 January 2020) and after the wave and return to work (7 April 2020 to 30 May 30 2020). One hundred paired semen and blood specimens from 100 donors were included. One-step single-tube nested quantitative real-time polymerase chain reaction (OSN-qRT-PCR) was used to detect SARS-CoV-2. Moreover, to control the unacceptable risk of false-negative results, a second round of screening was performed with pooled RNA from negative semen samples using crystal digital PCR (cd-PCR).For individual blood and semen samples, the target genes, namely the nucleocapsid protein (N) and open reading frame (ORF-1ab) genes, tested negative in all of the 100 paired samples. Further, as per cd-PCR results, there were20,000 droplets per well in the RNA for each combined sample and no positive droplets were present for either of the aforementioned target genes. A total of 100 paired semen and blood samples from these two groups tested negative for SARS-CoV-2.Cryopreserved semen at the Hunan Province Human Sperm Bank during and after the COVID-19 pandemic wave was free of SARS-CoV-2 and was judged safe for external use in the future.

Thanks to their tunability and versatility, colloidal quantum dots (CQDs) have been attracting very much interest for laser technology. Such CQDs made of II-VI semiconductor compound offer the potential to bridge the “green gap” in conventional semiconductor materials. However, in optical pump laser configuration, when the energy of excitation photons is much greater than that of emission photons, multiexciton interaction is enhanced, leading to reduced stimulated emission cross-section, broadened gain bandwidth, and enhanced photoinduced absorption. Here, to circumvent this drawback, for the first time, we show a fully colloidal gain in green enabled by a partially indirect pumping approach assisted by Förster resonance energy transfer process from blue-emitting CQDs to green ones. By introducing the blue CQDs as exciton donors, the lasing threshold of the acceptor, green CQDs, is reduced dramatically although the photon energy of optical pump is much higher compared to the bandgap energy. The blue CQDs thus serve as an energy-transferring buffer medium to reduce excitation energy from pumping photons in a controlled way by injecting photo-induced excitons into green CQDs. Our newly developed colloidal pumping scheme could enable efficient CQD lasers of full visible colours by a single pump source and cascaded exciton transfer. This would potentially pave the way for an efficient multicolour laser for lighting and display applications. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version The authors would like to thank the financial support from Singapore National Research Foundation under NRF-CRP-6–2010–02 and NRF-NRFI2016-08. We would like to thank Tao Ding and Kah Ee Fong for providing CQDs that were synthesized at Luminous! Centre of Excellence for Semiconductor Lighting and Displays. The electron microscopy imaging was performed at the Facility for Analysis, Characterization, Testing and Simulation (FACTS) at Nanyang Technological University, Singapore. Financial support from Nanyang Technological University start-up grant M4080514 and M4081482, the Ministry of Education AcRF Tier 1 grant RG 9215, RG101/15, RG 70/15 and Tier 2 grants MOE2013-T2-1-081 and MOE2014-T2-1-044; the Singapore National Research Foundation (NRF) through the Singapore–Berkeley Research Initiative for Sustainable Energy (SinBeRISE) CREATE Program and the Competitive Research Program NRF-CRP14-2014-03 is also gratefully acknowledged. HVD gratefully thanks TUBA.

Flexible information displays are key elements in future optoelectronic devices. Quantum dot light-emitting diodes (QLEDs) with advantages in color quality, stability, and cost-effectiveness are emerging as a candidate for single-material, full color light sources. Despite the recent advances in QLED technology, making high-performance flexible QLEDs still remains a big challenge due to limited choices of proper materials and device architectures as well as poor mechanical stability. Here, we show highly efficient, large-area QLED tapes emitting in red, green, and blue (RGB) colors with top-emitting design and polyimide tapes as flexible substrates. The brightness and quantum efficiency are 20 000 cd per m2 and 4.03percent, respectively, the highest values reported for flexible QLEDs. Besides the excellent electroluminescence performance, these QLED films are highly flexible and mechanically robust to use as electrically driven light-emitting stickers by placing on or removing from any curved surface, facilitating versatile LED applications. Our QLED tapes present a step toward practical quantum dot based platforms for high-performance flexible displays and solid-state lighting. ASTAR (Agency for Sci., Tech. and Research, S’pore)