Northeast Pacific warm blobs sustained via extratropical atmospheric teleconnections.

Large-scale marine heatwaves in the Northeast Pacific (NEP), identified here and previously as 'warm blobs', have devastating impacts on regional ecosystems. An anomalous atmospheric ridge over the NEP is known to be crucial for maintaining these warm blobs, also causing abnormally cold temperatures over North America during the cold season. Previous studies linked this ridge to teleconnections from tropical sea surface temperature anomalies. However, it was unclear whether teleconnections from the extratropics could also contribute to the ridge. Here we show that planetary wave trains, triggered by increased rainfall and latent heat release over the Mediterranean Sea accompanied by decreased rainfall over the North Atlantic, can transport wave energy to the NEP, guided by the westerly jet, and induce a quasi-barotropic ridge there. Our findings provide insights into extratropical teleconnections sustaining the NEP ridge, offering a source of potential predictability for the warm blobs and temperature fluctuations over North America.

A cryo-bulge apparatus for in situ weather balloon crystallization capturing during blowing by synchrotron radiation x-ray scattering.

A cryo-bulge apparatus, which can be directly installed in the synchrotron radiation x-ray scattering beamline, is designed and manufactured. Using the cryo-bulge apparatus, the crystallization of natural rubber during blowing can be captured in situ. For mechanical measurements, the rubber film is tightly clamped at the periphery of a circular window. A low temperature measurement is achieved by the presence of a large iron block, which ensures low temperature variation (<±2 °C in 1 h) during x-ray data acquisition. Since the incident x-ray beam passes through the top-most position of the rubber film, the information obtained by the current equipment is essentially under an equibiaxial deformation mode. Owing to precisely controlled internal pressure and temperature, the crystallization of rubber can be observed in situ by wide-angle x-ray scattering. The onset of crystallization is observed at a temperature T < 0 °C with an internal pressure P > 21 kPa. This suggests that the crystallization of rubber during blowing can occur under the equibiaxial deformation condition at low temperatures. The power scaling law is found to be 0.52%/kPa. The cryo-bulge apparatus is capable of clarifying the microstructural evolution of rubber during multi-dimensional deformation, which can provide guidance for the optimization of a weather balloon.

Melt-processed poly (vinyl alcohol)/corn starch/nanocellulose composites with improved mechanical properties.

Corn starch (CS) and cellulose nanofibrils (CNFs) were incorporated into biodegradable poly (vinyl alcohol) (PVA) to prepare mechanically robust and sustainable composites through melt-processing. Based on the regulation and control of hydrogen bonding network, CS and CNFs can extend the processing window and improve the thermoplasticity of PVA composites. Fourier transform infrared spectroscopy and Raman spectra analysis indicate that the intra- and inter-molecular hydrogen bonds of PVA are broken, accompanied by the formation of new hydrogen bonds among PVA, CS and CNFs during the melt-processing treatment. Thermal analysis shows that the processing window of PVA composite is significantly broadened to 131.46 °C. The tensile strength, modulus and elongation at break of the composites reach to 28.19 MPa, 1572.54 MPa and 10.72% by the incorporation of 10 wt% CS and 10 wt% CNFs. This strategy is not only expected to provide a direction for preparing complex three-dimensional products of PVA by melt-processing, but also provide a method to enhance the mechanical properties of other biodegradable plastics.

Oxidative alkylation/alkynylation of terminal alkenes via alkylaldehyde decarbonylation and 1,2-alkynyl migration.

A metal-free oxidative alkene alkylation/alkynylation of 1,4-enyn-3-ols with alkylaldehydes has been achieved, which offers a general access to the challenging quaternary carbon-containing but-3-yn-1-ones. The method features excellent functional group tolerance, broad substrate scope and exquisite selectivity, and provides a strategy for the difunctionalization of functional alkenes and utilization of alkylaldehydes as alkylating reagents through decarbonylation and 1,2-alkynyl migration.

Naturally Derived Wearable Strain Sensors with Enhanced Mechanical Properties and High Sensitivity.

Flexible strain sensors are of great interest for future applications in the next-generation wearable electronic devices. However, most of the existing flexible sensors are based on synthetic polymer materials with limitations in biocompatibility and biodegradability, which may lead to potential environmental pollution. Here, we propose a naturally derived wearable strain sensor based on natural-sourced materials including milk protein fabric, natural rubber, tannic, and vitamin C. The obtained sensors exhibit remarkably enhanced mechanical properties and high sensitivity contrast to currently reported natural resource-based sensors, owing to the metal-ligand interface design and the construction of an organized three-dimensional conductive network, which well fit the requirements of electronic skin. This work represents an important advance toward the fabrication of naturally derived high-performance strain sensors and expanding possibilities in the design of environmental-friendly soft actuators, artificial muscle, and other wearable electronic devices.

Immobilization of rubber additive on graphene for high-performance rubber composites.

It is still a challenge to achieve simultaneous improvements in aging resistance, mechanical strength, thermal conductivity and dielectric constant of rubber composites via incorporation of graphene obtained by conventional methods. Herein, an effective and green method was proposed to simultaneously reduce and functionalize graphene oxide (GO) with 2-mercaptobenzimidazole (antioxidant MB) via a one-pot method. GO was successfully reduced by MB which was also chemically grafted on the reduced GO (G-MB). G-MB sheets were uniformly dispersed in rubber with strong interfacial interaction, and graphene-graphene conductive paths were formed through intermolecular H-bonding between the grafted antioxidant molecules. Consequently, rubber composites with G-MB showed higher thermal conductivity, mechanical strength and dielectric constant than rubber composites with hydrazine hydrate reduced GO (rGO). Moreover, the thermo-oxidative aging resistance of rubber composites with G-MB was also superior to that of rubber composites with rGO because of the elimination of blooming effect of the grafted MB molecules. Thus, this work may open a new way for the eco-friendly functionalization and reduction of GO and may boost the development of high-performance, functional graphene-elastomer composites.

Cerium oxide immobilized reduced graphene oxide hybrids with excellent microwave absorbing performance.

Microwave absorbing materials with high absorption over a broad bandwidth when they have a small thickness are strongly desired due to their widespread applications. Herein, cerium oxide immobilized reduced graphene oxide (CeO2-rGO) hybrids with excellent microwave absorbing performance have been fabricated by a versatile one-step hydrothermal approach. Modern measurement techniques, including X-ray diffraction, Raman spectroscopy, electronic microscopy, X-ray photoelectron spectroscopy and vector network analysis, have been conducted to characterize the chemical composition, microstructure and electromagnetic performance of the as-obtained hybrids. Morphological analysis reveals that the CeO2 nanocrystals are homogeneously immobilized onto the rGO surface without any significant agglomeration. Interestingly, significant enhancement in the microwave absorbing performance has been observed for all the CeO2-rGO hybrids. For example, a CeO2-rGO hybrid with a 10 : 1 mass ratio of CeO2 to GO exhibits a minimum reflection loss (RL) of -45.94 dB, which is 73.35 times and 6.14 times that of the lone CeO2 and rGO, respectively. Moreover, the CeO2-rGO hybrid shows a broadband absorption feature with an effective absorption bandwidth (RL < -10 dB) of 4.5 GHz, and can be exploited for practical application in a frequency range of 3.68-18.00 GHz via tuning of the thickness. Investigation of the structure-property correlation indicates that such enhancements are attributed to conductive loss, polarization loss and multiple reflections which are mainly derived from the unique CeO2-rGO based architecture. In addition, the higher oxygen vacancy concentration of CeO2 in hybrids can promote electron transfer between CeO2 and rGO, leading to microwave attenuation enhancement. It is expected that these CeO2-rGO hybrids can be used as new microwave absorbers.

Self-Healing Sensors Based on Dual Noncovalent Network Elastomer for Human Motion Monitoring.

Nowadays, it is still a challenge to prepare flexible sensors with great mechanical strength, stretchability, high sensitivities, and excellent self-healing (SH) abilities. Herein, a nanostructured supramolecular elastomer is reported with a dual noncovalent network of hydrogen bonding interactions and metal-ligand coordination. The resultant flexible sensor presents ultrafast (30 s), autonomous, and repeatable SH ability with high healing efficiency (80% after the 3rd healing process), as well as enhanced mechanical properties. Benefitting from the 3D conductive network, the sensor exhibits high electrical sensitivity and very low detection limit (0.2% strain). As a result, the flexible sensor is capable of precisely monitoring small strains of human motions (such as vocal-cord vibration), and exhibits reproducible and recognizable current signals after cutting-healing process. The dual noncovalent network design proposed here opens up a new opportunity for scalable fabrication of high performance SH sensors and other electronic devices.