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Silica/resorcinol–formaldehyde (RF) hybrid xerogels with low shrinkage were prepared efficiently in an environmental-friendly way through a two-step method and ambient drying process. Poly(diallyldimethylammonium chloride) (PDADMAC) was used as a soft template, aqueous solution of resorcinol and formaldehyde was used as organic source, and hydrosol of tetraethoxysilane and methyltriethoxysilane was used as inorganic source. Then, the hybrid xerogel sample was grafted with trimethylchlorosilane to improve its hydrophobicity. By adjusting the amount of PDADMAC, the minimum shrinkage can be controlled at about 2%. With the slight increase of pH from 2.13 to 2.98, the average pore size decreased sharply from 24.82 to 0.47 μm, and the specific surface area increased significantly from 0.63 to 26.51 m2/g, but it still maintained the characteristics of low shrinkage (1.16–2.18%), low density (0.20–0.25 cm3/g) and high porosity (~ 80%). Scanning electron microscopy (SEM) analysis showed that the polysiloxane formed a continuous coating on the surface of the RF resin skeleton, and the average particle size decreased from micron level to nanometer level. Mechanics testing indicated that its elastic modulus is as high as 37.26 MPa. Thermogravimetric analysis in air revealed that the weight loss rate of hybrid modified samples slowed down at the high-temperature range (200–600 °C), and the residual weight increased from 0.65 to 13.80% at 800 °C. The water contact angle test before and after hydrophobic modification demonstrated that the contact angle increased sharply from 0° (superhydrophobic) to 160° (superhydrophobic). [ABSTRACT FROM AUTHOR]

In this paper, laser welding-brazing of TC4 Titanium (Ti) alloy and Al2O3 ceramic dissimilar material was carried. The results showed that the Ti alloy and Al2O3 were joined by melting filler metal when the laser was concentrated in the Ti alloy side of the joint. The joint with one fusion weld and one brazed weld separated by remaining unmelted Ti alloy. Laser beam offset the Ti alloy 1.5 mm, Ti alloy would not be completely melted in joint. Through heat conduction, the filler metal melted occurred at the Ti-ceramic interface. A brazed weld was formed at the Ti-ceramic interface with the main microstructure of β-CuZn + Ti2Zn3, β-CuZn and Al2Cu + β-CuZn. The joint fractured at the brazed weld with the maximum tensile strength of 169 MPa. [ABSTRACT FROM AUTHOR]

The media access control (MAC) performance of a large-scale wireless sensor network (L-WSN) determines the efficiency of the wireless communication channel. A good MAC protocol could reduce network energy consumption and network delay, which are two problems to be solved urgently in L-WSN. In this paper, we proposed a multi-level integrated MAC protocol (MI-MAC) to solve the overall performance optimization problem of L-WSN. Compared with other protocols, MI-MAC has two mainly improved performances: (1) It improved binary exponential backoff algorithm by twice back off strategy; (2) It designed a sending and receiving algorithm based on the threshold value to recognize control frames (small frames), which effectively avoids the collision probability of data frame. The simulation results show that the MI-MAC protocol improves network throughput and delay performance, significantly reduces energy consumption, and obtains overall network optimization. [ABSTRACT FROM AUTHOR]

Angiotensin II type-1 receptor–neprilysin inhibitor (ARNi) is consisted of Angiotensin II type-1 receptor (AT1) antagonist and neprilysin (NEP) inhibitor, which could simultaneously increase the vasodilators of the natriuretic peptides and antagonize vasoconstrictors of Ang II. ARNi has been proved a superior effect and lower risks of death on chronic heart failure (CHF) and hypertension. In this paper, ARNi from Traditional Chinese Medicines (TCM) was discovered based on target combination of AT1 and NEP by virtual screening, biological assay and molecular dynamics (MD) simulations. Two customized strategies of combinatorial virtual screening were implemented to discover AT1 antagonist and NEP inhibitor based on pharmacophore modeling and docking computation respectively. Gyrophoric acid (PubChem CID: 135728) from Parmelia saxatilis was selected as AT1 antagonist and assayed with IC50 of 29.76 μM by calcium influx assay. And 3,5,3′-triiodothyronine (PubChem CID: 861) from Bos taurus domesticus was screened as NEP inhibitor and has a dose dependent inhibitory activity by biochemistry fluorescence assay. Combined with MD simulations, these compounds can generate interaction with the target, key interactive residues of ARG167, TRP84, and VAL108 in AT1, and HIS711 in NEP were also identified respectively. This study designs the combinatorial strategy to discover novel frames of ARNi from TCM, and gyrophoric acid and 3,5,3′-triiodothyronine could provide the clues and revelations of drug design and therapeutic method of CHF and hypertension for TCM clinical applications. [ABSTRACT FROM AUTHOR]

Recent years have seen a surge in the use of low-dimensional transition metal dichacolgenides, such as MoS2, as catalysts for the electrochemical hydrogen evolution reaction. In particular, sulfur vacancies in MoS2 can activate the inert basal plane, but that requires an unrealistically high defect concentration (~9%) to achieve optimal activity. In this work, we demonstrate by first-principles calculations that assembling van der Waals heterostructures can enhance the catalytic activity of MoS2 with low concentrations of sulfur vacancies. We integrate MoS2 with various two-dimensional nanostructures, including graphene, h-BN, phosphorene, transition metal dichacolgenides, MXenes, and their derivatives, aiming to fine-tune the free energy of atomic hydrogen adsorption. Remarkably, an optimal free energy can be achieved for a low sulfur vacancy concentration of ~2.5% in the MoS2/MXene-OH heterostructure, as well as high porosity and tunability. These results demonstrate the potential of combining two-dimensional van der Waals assembly with defect engineering for efficient hydrogen production. [ABSTRACT FROM AUTHOR]