Printable and filament-drawable PDMS based adhesive assisted manufacturing of highly conductive copper micro-patterns.

Manufacturing of copper micro-patterns is crucial in electronics for its utilization as high conductivity transparent conductive films (TCFs) and circuits. In the preparation process of current TCFs, a plethora of materials have emerged that can replace traditional indium tin oxide (ITO). However, even for the most promising metal-based nanowire materials, there are issues such as high cost, complex welding, and high contact resistance. To address these problems, this paper proposes a printable and filament-drawable polydimethylsiloxane (PDMS)-based adhesive, which, through a novel additive patterning technology, efficiently and economically manufactures self-welding copper micro-meshes and circuits. The adhesive can be processed into micro-patterns through printing and filament drawing, on which ionic Ag can be in situ reduced and anchored, thereby eliminating the need for tedious pre- and post-treatment steps. The fully exposed Ag particles dramatically minimize the usage of precious metal catalyst, thus efficiently catalyzing electroless copper deposition (ECD) reaction. Highly conductive (1.03 × 107 S m-1) copper circuits can be fabricated on the printed adhesive patterns, exhibiting versatile applicability to diverse substrates. Highly precise copper micro-meshes (∼50 µm) can be fabricated on the filament networks drawn by the adhesive. The copper meshes undergo complete self-welding at junctions during the ECD process, thus exhibiting ultra-low square resistance of 0.45 Ω sq-1 while maintaining a high transmittance of 82.2 %. This is far superior to most of TCFs in published literature.

Synergy of P doping and crystallinity modulation in carbon nitride for enhancing photocatalytic uranyl reduction.

Doping modification is a useful way to promote the catalytic activity of carbon nitride (CN). However, most doped CNs have lower structural symmetry and several edge defects, which hinder the transfer of charge carriers. This work reports a P-doped crystalline carbon nitride (crystalline PCN) for the efficient photoreduction of uranyl. The thermal polymerization and salt post-treatment convert the amorphous PCN into crystalline PCN. Compared to the pristine CN, the crystalline PCN has over 1620 % higher activity for uranyl (U(VI)) reduction, reaching a 97.8 % reduction rate in 60 min. Furthermore, the 2-PCN shows excellent stability and a U(VI) removal efficiency >85.7 % in the pH range of 5-8. Characterization analysis reveal that both the P doping and crystalline modulation do not obviously change their morphology, light absorption property and energy band structure, but markedly promote the delocalization of electrons around the doped P atoms, thereby severely inhibit direct electron-hole recombination. Thus, the more efficient separation of charge carriers generates more reactive specials to participate in the photocatalytic uranyl reduction reaction. This study demonstrates a dual-modification strategy for the rational synthesis of highly active metal-free CN-based photocatalysts for uranyl reduction.

Novel-miR-81 Promotes the Chondrocytes Differentiation of Bone Marrow Mesenchymal Stem Cells Through Inhibiting Rac2 Expression.

OBJECTIVE: MicroRNAs (miRNAs) play a key role in the differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) into chondrocytes. Our previous study found that novel-miR-81 can relieve osteoarthritis, but its role in chondrogenic differentiation of BMSCs remains unclear. The purpose of this study was to explore the role of novel-miR-81 in chondrogenic differentiation of BMSCs. METHODS: We used a model in which transforming growth factor (TGF)-ß3-induced BMSCs differentiation into chondrocytes. We detected the expression Sox9, Collagen Ⅱ, Aggrecan, novel-miR-81, and Rac2 by real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Western blot was performed to detect the expression of Sox9, Collagen Ⅱ, and Rac2. Dual-luciferase reporter gene assay confirmed that the association between novel-miR-81 and Rac2. In addition, the ectopic chondrocyte differentiation of BMSCs was performed subcutaneously in nude mice. The effect of novel-miR-81 and Rac2 on ectopic chondrogenic differentiation of BMSCs was determined by immunohistochemical staining. RESULTS: Novel-miR-81 upregulated in chondrogenic differentiation of BMSCs. Rac2 was a key target of novel-miR-81. Mimic novel-miR-81 and siRac2 upregulated the expression of Sox9, Collagen Ⅱ, and Aggrecan. CONCLUSION: Novel-miR-81 promotes the chondrocytes differentiation of BMSCs by inhibiting the expression of target gene Rac2, which provides potential targets for BMSCs transplantation to repair cartilage defects.

rno-miR-90 promotes chondrogenic differentiation of bone marrow mesenchymal stem cells by targeting SPARC-related modular calcium binding 2.

Bone marrow mesenchymal stem cells (BMSCs) have the ability to differentiate into chondrocytes. In the differentiation of BMSCs into chondrocytes, micro-RNAs (miRNAs) play an important role. rno-miR-90 is a new miRNA discovered by our research team, and its role in chondrogenic differentiation of BMSCs is unknown. This study aimed to investigate whether rno-miR-90 could promote chondrogenic differentiation of BMSCs by regulating secreted protein acidic and rich in cysteine-related modular calcium binding 2 (Smoc2). First, BMSCs chondroblast differentiation was successfully induced in vitro by classical induction method of transforming growth factor (TGF)-ß3. On this basis, we transfected rno-miR-90 mimic and inhibitor, and confirmed that rno-miR-90 mimic could promote the differentiation of BMSCs into chondrocytes by real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting. In addition, we demonstrated that Smoc2 was a target gene of rno-miR-90 by dual-luciferase reporter assay, and confirmed that rno-miR-90 mimic could inhibit the expression of Smoc2 by RT-qPCR and western blotting. In order to further prove the targeting relationship between rno-miR-90 and Smoc2, we constructed three interfering fragments of Smoc2, and proved that silencing Smoc2 could promote the differentiation of BMSCs into chondrocytes at the transcriptional and protein levels. Finally, we constructed a carrier scaffold for ectopic chondrogenic differentiation in vivo, and confirmed that rno-miR-90 mimic and siSmoc2 could promote chondrogenic differentiation of BMSCs by Alcian blue staining and immunohistochemistry. In summary, our results suggested that rno-miR-90 could promote chondrogenic differentiation of BMSCs by down-regulating the expression of Smoc2. rno-miR-90 mimic and Smoc2 may be therapeutic targets of osteoarthritis.

Room-Temperature Welding of Silver Telluride Nanowires for High-Performance Thermoelectric Film.

Flexible thermoelectric materials that can harvest waste heat energy have attracted great attention because of the rapid progress of flexible electronics. Ag2Te nanowires (Ag2Te NWs) are considered as promising thermoelectric materials to fabricate flexible thermoelectric film and device because of their high Seebeck coefficient, but poor contact between the Ag2Te NWs results in low electrical conductivity. Generally, hot or cold pressing can increase the electrical conductivity between the Ag2Te NWs. However, these process tend to destroy the initial morphology of the Ag2Te NWs and/or cause only physical contact between the Ag2Te NWs. Herein, we report an approach to the room-temperature welding of Ag2Te NWs to enhance their contacts by facile combination of vacuum filtration and drop-coating methods. The obtained Ag2Te NWs film exhibits excellent Seebeck coefficient of -99.48 µV/K and high electrical conductivity of 15 335.05 S/m at room temperature, which gives the power factor of 151.76 µW m-1 K-2. Surprisingly, an optimal Seebeck coefficient of -154.96 µV/K and electrical conductivity of 14 982.42 S/m can be obtained at 420 K, giving a power factor of 359.76 µW m-1 K-2. Moreover, the electrical resistance of the Ag2Te NWs film was only 1.3 times of the initial electrical resistance after 1000 bending cycles, indicating good flexibility of the film. A finger-touch test is conducted by using the Ag2Te NWs film as thermoelectric power generator, which achieves a stable output voltage of about 0.52 mV, suggesting its great potential applications in self-powered flexible electronic devices.