To meet the increasing demands for effective heat management of electronic devices, a graphene-based polymeric composite is considered to be one of the candidate materials owing to the ultrahigh ...thermal conductivity (TC) of graphene. However, poor graphene dispersion, low quality of exfoliated graphene, and strong phonon scattering at the graphene/matrix interface restrict the heat dissipation ability of graphene-filled composites. Here, a facile and versatile approach to bond graphene foam (GF) with polydimethylsiloxane (PDMS) is proposed, and the corresponding composite with considerable improvement in TC and insulativity is fabricated. First, three-dimensional GF was coated with polydopamine (PDA) via π–π stack and functional groups from PDA reacted with 3-aminopropyltriethoxysilane (APTS). Then, the modified GF was compressed (c-GF) to enhance density and infiltrated with PDMS to get the c-GF/PDA/APTS/PDMS composite. As a result, these processes endow the composite with high TC of in-plane 28.77 W m–1 K–1 and out-of-plane 1.62 W m–1 K–1 at 11.62 wt % GF loading. Besides, the composite manifests obvious improvement in mechanical properties, thermal stability, and insulativity compared to neat PDMS and GF/PDMS composite. An attempt to use the composite for cooling a ceramic heater is found to be successful. Above results open a way for such composites to be applied for the heat management of electronic devices.
Uncovering the mechanisms of virus infection and assembly is crucial for preventing the spread of viruses and treating viral disease. The technique of single-virus tracking (SVT), also known as ...single-virus tracing, allows one to follow individual viruses at different parts of their life cycle and thereby provides dynamic insights into fundamental processes of viruses occurring in live cells. SVT is typically based on fluorescence imaging and reveals insights into previously unreported infection mechanisms. In this review article, we provide the readers a broad overview of the SVT technique. We first summarize recent advances in SVT, from the choice of fluorescent labels and labeling strategies to imaging implementation and analytical methodologies. We then describe representative applications in detail to elucidate how SVT serves as a valuable tool in virological research. Finally, we present our perspectives regarding the future possibilities and challenges of SVT.
A series of novel flexible polymer composites consisted of boron nitride foam (BNF), boron nitride nanosheets (BNNS) and polydimethylsiloxane (PDMS) were designed and fabricated by vacuum-assisted ...infiltrating BNNS/PDMS mixtures into 3D BNF synthesized via chemical vapor deposition (CVD). Their microstructure, thermal, mechanical and dielectric properties were studied. Contributed to the interconnected networks of BNF and synergistic effect of BNNS with BNF, 10wt% BNNS/BNF/PDMS composite shows a high thermal conductivity of 0.56Wm−1K−1, high heat resistance index of 275.6°C, 33% increment of Young’s modulus compared to PDMS, relative permittivity of 3, dissipation factor of 0.0051, EMI shielding effectiveness of 1.5dB at X band and breakdown strength of 21.8MV/m. Due to the outstanding comprehensive properties, BNNS/BNF/PDMS composites have a promising potential application in wide electronic packaging field.
Emotion recognition based on physiological signals has been a hot topic and applied in many areas such as safe driving, health care and social security. In this paper, we present a comprehensive ...review on physiological signal-based emotion recognition, including emotion models, emotion elicitation methods, the published emotional physiological datasets, features, classifiers, and the whole framework for emotion recognition based on the physiological signals. A summary and comparation among the recent studies has been conducted, which reveals the current existing problems and the future work has been discussed.
Amino groups are common in both natural and synthetic compounds and offer a very attractive class of endogenous handles for bioconjugation. However, the ability to differentiate two types of amino ...groups and join them with high hetero‐selectivity and efficiency in a complex setting remains elusive. Herein, we report a new method for bioconjugation via one‐pot chemoselective clamping of two different amine nucleophiles using a simple ortho‐phthalaldehyde (OPA) reagent. Various α‐amino acids, aryl amines, and secondary amines can be crosslinked to the ϵ‐amino side chain of lysine on peptides or proteins with high efficiency and hetero‐selectivity. This method offers a simple and powerful means to crosslink small molecule drugs, imaging probes, peptides, proteins, carbohydrates, and even virus particles without any pre‐functionalization.
Simple ortho‐phthalaldehyde (OPA) reagent enables a facile and broadly applicable bioconjugation strategy via hetero‐selective clamping of two different endogenous amino handles such as ϵ‐NH2 of lysine and α‐NH2 of α‐amino acids without any pre‐functionalization.
During mammalian embryonic development, primary cilia transduce and regulate several signaling pathways. Among the various pathways, Sonic hedgehog (SHH) is one of the most significant. SHH signaling ...remains quiescent in adult mammalian tissues. However, in multiple adult tissues, it becomes active during differentiation, proliferation, and maintenance. Moreover, aberrant activation of SHH signaling occurs in cancers of the skin, brain, liver, gallbladder, pancreas, stomach, colon, breast, lung, prostate, and hematological malignancies. Recent studies have shown that the tumor microenvironment or stroma could affect tumor development and metastasis. One hypothesis has been proposed, claiming that the pancreatic epithelia secretes SHH that is essential in establishing and regulating the pancreatic tumor microenvironment in promoting cancer progression. The SHH signaling pathway is also activated in the cancer stem cells (CSC) of several neoplasms. The self-renewal of CSC is regulated by the SHH/Smoothened receptor (SMO)/Glioma-associated oncogene homolog I (GLI) signaling pathway. Combined use of SHH signaling inhibitors and chemotherapy/radiation therapy/immunotherapy is therefore key in targeting CSCs.
We develop a nonperturbative method through the Hartree factorization to examine the quantum fluctuation effects on the single-field inflationary models in a spatially flat FRW cosmological ...space-time. Apart from the background field equation as well as the Friedmann equation with the corrections of quantum field fluctuations, the modified Mukhanov-Sasaki equations for the mode functions of the quantum scalar field are also derived by introducing the nonzero ΔB term. We consider the Universe undergoing the slow roll (SR)-ultra slow roll (USR) -slow roll (SR) inflation where in particular the presence of the USR inflation triggers the huge growth of ΔB that in turn gives the boost effects to the curvature perturbations for the modes that leave horizon in the early times of the inflation. However, the cosmic friction term in the mode equation given by the Hubble parameter presumably prohibits the boost effects. Here we propose two representative models to illustrate these two competing terms.
Summary
The plant immune system features numerous immune receptors localized on the cell surface to monitor the apoplastic space for danger signals from a broad range of plant colonizers. Recent ...discoveries shed light on the enormous complexity of molecular signals sensed by these receptors, how they are generated and removed to maintain cellular homeostasis and immunocompetence, and how they are shaped by host‐imposed evolutionary constraints. Fine‐tuning receptor sensing mechanisms at the molecular, cellular and physiological level is critical for maintaining a robust but adaptive host barrier to commensal, pathogenic, and symbiotic colonizers alike. These receptors are at the core of any plant‐colonizer interaction and hold great potential for engineering disease resistance and harnessing beneficial microbiota to keep crops healthy.
A novel fixed-frequency beam-scanning leaky-wave antenna (LWA) based on a period-reconfigurable structure is presented. Operating at 5 GHz, the antenna consists of a slotted substrate integrated ...waveguide and 54 electrically small patches. Each patch element is etched with two dumbbell-shaped slots, and its operating state can be flexibly controlled by the biasing of the p-i-n diode on a parasitic strip. An ideal array model employing isotropic point sources is used for the analysis on the scanning mechanism, based on which a new method for suppressing the higher order space harmonics is developed. Using this method, the monoharmonic radiation range can be dramatically extended, and a wide-angle beam scanning can be achieved by manipulating the period length of the LWA. An FPGA controlling platform is designed for the electronic control of the antenna. The measured results validate that the proposed antenna achieves good performance of wide-angle scanning (125°) with a peak gain of 11.8 dBi at a fixed frequency.
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