Electrochemical activation is an effective method for synthesizing economically feasible heterogeneous hydrogen evolution reaction (HER) electrocatalysts. Herein, we first synthesized MoO2-Co2Mo3O8 precatalyst, which was electrochemically activated to produce K2Mo3O10 within the original phase to form the heterogeneous structure. The electrochemically activated samples demonstrate exceptional HER activity in alkaline medium, which exhibit a low overpotential of 31 mV at current density of 10 mA cm−2 (135 mV at 100 mA cm−2), as well as a small Tafel slope of 34 mV dec−1. This is due to the creation of multiphase heterostructures that prompt interfacial interactions and accelerate charge transfer. Simultaneously, the creation of additional active sites increases their intrinsic activities. The combined effects collectively enhance the HER performance. The application of this method in the preparation of HER catalysts is still relatively unexplored, thus rendering our work a pioneering contribution to the field.

The carbon fiber-reinforced plastic (CFRP) tubular structure is suitable for aircraft and aerospace applications requiring strong axial strength and moderate thermal expansion. However, utilizing CFRP tubular constructions necessitates the addition of end-fitting components, which introduces new problems, such as adhesion. This study presented a novel two-step sheet-winding compression-molding (SWCM) process for fabricating integral thermosetting CFRP tubular-bar structure elements, which could be further drilled into a tubular-lug structural element. The influence of the proposed SWCM technique on the curing of the epoxy prepregs is demonstrated to be minor. The mechanical characteristics of SWCM specimens are much superior to those of control autoclave samples. The investigation of morphology provides a discussion and assumptions regarding the enhancement mechanism. It is considered that the advantage of SWCM specimens is that the particular wrapped edge suppresses the effect of free-edge delamination. This study provides a valuable guideline for designing and fabricating tubular-lug structural components.

Abstract Genome editing by homology directed repair (HDR) is leveraged to precisely modify the genome of therapeutically relevant hematopoietic stem and progenitor cells (HSPCs). Here, we present a new approach to increasing the frequency of HDR in human HSPCs by the delivery of i53 recombinant protein. We show that the use of i53 peptide effectively increases the frequency of HDR-mediated genome editing at a variety of therapeutically relevant loci in HSPCs as well as other primary human cell types. We show that incorporating the use of i53 recombinant protein allows high levels of HDR to be attained while lowering the amounts of AAV6 needed by 8-fold. HDR edited HSPCs were capable of long-term and bi-lineage hematopoietic reconstitution in NSG mice, suggesting that i53 recombinant protein might be safely integrated into the standard CRISPR/AAV6-mediated genome editing protocol to gain greater numbers of edited cells for transplantation of clinically meaningful cell populations.

A comparative study of the characteristics of two fiber-filled molding materials, which include a discrete carbon viscose fiber as a filler and phenol-formaldehyde resins of the novolac or resol type as a binder, is given. The DTA-DTG characteristics of the initial resins and the physico-mechanical properties of carbon fiber blanks obtained from fiber-filled molding materials of these types by hot compression molding were determined. It has been established that, regardless of the type of phenol-formaldehyde resin, the density, strength characteristics, toughness and thermal conductivity of carbon fiber plastics based on various resins are practically the same. A comparison of the microstructure of the obtained carbon fiber plastics based on various resins showed that in the case of using phenol-formaldehyde resin of the novolac type, a higher degree of orientation of the fiber filaments parallel to the pressing plane is achieved, which is associated with greater fluidity of the initial fiber-filled molding material. In the direction perpendicular to the pressing axis, the chaotic orientation of the fiber filaments is realized.

Abstract Annular pressure buildup (APB) can occur due to an increase in fluid temperature during the production of hot reservoir fluids, geomechanical loading from the surrounding rock formation, and hydraulic connectivity to pressurized reservoirs. In this study, a novel, compressible, carbonaceous fluids additive was deployed and tested for APB mitigation in a well-scale field trial. The additive is shown to appreciably reduce pressure changes in trapped, downhole volumes by increasing the fluid mixture's compressibility and reducing its thermal expansivity. The proposed additive, referred to as compressible carbon, is a granular spongy carbon with an internal porosity that remains closed to fluid ingress. Lab-scale results demonstrate the durability of compressible carbon in high temperature and high pressure environments when immersed in typical drilling fluids. At a loading of 20% by volume, the use of carbon reduced pressure buildup by 30%-50% relative to reference measurements performed in fluids without carbon. Moreover, the particles showed no long-term relaxation while being held at 10,000 psi and 220°F for up to three months, and exhibited only a marginal loss in reversible compressibility over 100s of pressure cycles between 500psi and 13,500psi. Following the material's characterization in the lab, field trial results were collected during the deployment and testing of carbon in two unconventional land wells above the cemented section of the production-by-intermediate annulus. Wireline logging on both wells confirmed minimal fluid losses to the formation and an adequate cement barrier that reached above the outer-lying casing shoes. Field-scale performance of compressible carbon was confirmed by pressuring up on the annuli at surface and comparing the injection volumes to those collected on an offset well without carbon. Although alternate methods of reducing pressure buildup in wells exist, compressible carbon is a versatile new material that provides repeated APB relief across the pressure ranges that are relevant to deepwater wells. To minimize the risk of first application in deepwater wells, successful deployment and expected performance were demonstrated in two unconventional land wells, paving the way for subsequent applications offshore.

Many promising optoelectronic devices, such as broadband photodetectors, nonlinear frequency converters, and building blocks for data communication systems, exploit photoexcited charge carriers in graphene. For these systems, it is essential to understand the relaxation dynamics after photoexcitation. These dynamics contain a sub-100 fs thermalization phase, which occurs through carrier–carrier scattering and leads to a carrier distribution with an elevated temperature. This is followed by a picosecond cooling phase, where different phonon systems play a role: graphene acoustic and optical phonons, and substrate phonons. Here, we address the cooling pathway of two technologically relevant systems, both consisting of high-quality graphene with a mobility >10 000 cm2 V–1 s–1 and environments that do not efficiently take up electronic heat from graphene: WSe2-encapsulated graphene and suspended graphene. We study the cooling dynamics using ultrafast pump–probe spectroscopy at room temperature. Cooling via disorder-assisted acoustic phonon scattering and out-of-plane heat transfer to substrate phonons is relatively inefficient in these systems, suggesting a cooling time of tens of picoseconds. However, we observe much faster cooling, on a time scale of a few picoseconds. We attribute this to an intrinsic cooling mechanism, where carriers in the high-energy tail of the hot-carrier distribution emit optical phonons. This creates a permanent heat sink, as carriers efficiently rethermalize. We develop a macroscopic model that explains the observed dynamics, where cooling is eventually limited by optical-to-acoustic phonon coupling. These fundamental insights will guide the development of graphene-based optoelectronic devices.