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The effects of sintering parameters and liquid phase content on the properties of Fe-rich based pre-alloyed impregnated diamond bit (IDB) matrix were investigated using orthogonal experimental design. Based on the analysis of the results, it was found that sintering temperature and liquid phase content have significant effects on the bending strength, hardness, relative density, and wear rate of the matrix. For metal matrix composite (MMC), as the sintering temperature increased from 900 to 1050°C, the bending strength, hardness (HRB), and relative density of the MMC decreased first, then increased, and finally decreased again, while the wear rate increased with temperature. With increasing liquid phase content, the four properties of the MMC showed a similar trend of increasing first and then decreasing. Comparatively, the effects of holding time and sintering pressure on the properties of the matrices were smaller than those of sintering temperature and liquid phase content, but they also had significant effects on some properties of the matrices. Holding time had a more significant effect on hardness and wear resistance, while sintering pressure only had a significant effect on hardness. After adding diamonds, the bending strength of diamond matrix composite increased first and then decreased with increasing temperature, while the bending strength continued to decrease with the increase of liquid phase content. This study provides a feasible method for studying the effects of various sintering parameters and liquid phase content on the properties of Fe-rich pre-alloyed IDB matrix, which is helpful for optimizing the preparation process of drill bits. [ABSTRACT FROM AUTHOR]

Bacterial conjugation, a commonly used method to horizontally transfer functional genes from donor to recipient strains, plays an important role in the genetic manipulation of bacteria for basic research and industrial production. Successful conjugation depends on the donor‐recipient cell recognition and a tight mating junction formation. However, the efficiency of conjugative transfer is usually very low. In this work, we developed a new technique that employed DNA molecule "glue" to increase the match frequency and the interaction stability between the donor and recipient cells. We used two E. coli strains, ETZ and BL21, as a model system, and modified them with the complementary ssDNA oligonucleotides by click chemistry. The conjugation efficiency of the modified bacteria was improved more than 4 times from 10 %–46 %. This technique is simple and generalizable as it only relies on the active amino groups on the bacterial surface. It is expected to have broad applications in constructing engineered bacteria. [ABSTRACT FROM AUTHOR]

Extracellular vesicles (EVs) have emerged as promising biomaterials for the treatment of different disease. However, only handful types of EVs with clinical transformation potential have been reported to date, and their preparation on a large scale under biosafety‐controlled conditions is limited. In this study, we characterize a novel type of EV with promising clinical application potential: dehydration‐induced extracellular vesicles (DIMVs). DIMV is a type of micron‐diameter cell vesicle that contains more bioactive molecules, such as proteins and RNA, but not DNA, than previously reported cell vesicles. The preparation of DIMV is extraordinarily straightforward, which possesses a high level of biosafety, and the protein utilization ratio is roughly 600 times greater than that of naturally secreted EVs. Additional experiments demonstrate the viability of pre‐ or post‐isolation DIMV modification, including gene editing, nucleic acid encapsulation or surface anchoring, size adjustment. Finally, on animal models, we directly show the biosafety and immunogenicity of DIMV, and investigate its potential application as tumour vaccine or drug carrier in cancer treatment. [ABSTRACT FROM AUTHOR]

Stimulated emission depletion (STED) microscopy, as a popular super-resolution imaging technique, has been widely used in bio-structure analysis and resolving the dynamics of biological processes beyond the diffraction limit. The performance of STED critically depends on the optical properties of the fluorescent probes. Ideally, the probe should process high brightness and good photostability, and exhibit a sensitive response to the depletion beam. Organic dyes and fluorescent proteins, as the most widely used STED probes, suffer from low brightness and exhibit rapid photobleaching under a high excitation power. Recently, luminescent nanoparticles (NPs) have emerged as promising fluorescent probes in biological imaging due to their high brightness and good photostability. STED imaging using various kinds of NPs, including quantum dots, polymer dots, carbon dots, aggregation-induced emission dots, etc., has been demonstrated. This review will comprehensively review recent advances in fluorescent NP-based STED probes, discuss their advantages and pitfalls, and outline the directions for future development. [ABSTRACT FROM AUTHOR]

Various contents of carbon fibers (CFs) and potassium titanate whiskers (PTWs) were added to an Fe-based impregnated diamond bit (IDB) matrix to enhance its adaptability to percussive–rotary drilling. A series of mechanical tests were conducted successively to find the effects of the reinforcing materials on the properties of the Fe-based IDB samples. Then, the fracture surfaces of the samples were analyzed via scanning electron microscopy (SEM) and energy-dispersive spectroscopy, and the worn surfaces and abrasive debris of the samples were analyzed using a laser scanning confocal microscope and SEM. The results show that both the CF and PTW can effectively improve the hardness and bending strength of an Fe-based IDB matrix, and those parameters reached their maximum values at the additive amount of 1 wt%. However, the CF had a better enhancement effect than the PTW. Furthermore, the CF improved the impact wear resistance of the IDB matrix, with a minimum wear rate of 2.38 g/min at the additive amount of 2 wt%. However, the PTW continuously weakened the impact wear resistance of the IDB matrix with increases in its content. Moreover, the morphologies of the worn surfaces indicated that the minimum roughness of the CF-reinforced IDB matrix decreased significantly to as low as 4.91 μm, which was 46.16% lower than that without CF, whereas the minimum roughness of the PTW-reinforced samples decreased by 11.31%. Meanwhile, the abrasive debris of the CF-reinforced samples was more uniform and continuous compared to that of the PTW-reinforced samples. Overall, the appropriate addition of CF or PTWs can enhance the mechanical properties of Fe-based IDB matrices, which can be used on different formations based on their impact wear resistance. [ABSTRACT FROM AUTHOR]

The coupling of three-level giant atoms with one-dimensional waveguides can show interesting phenomena of transmission and reflection. Since the non-waveguide mode can cause the dissipation of external atoms, we consider the effect of the dissipation rate on the scattering of single photons in the system with giant atom–waveguide coupling. We find that as the dissipation rate of giant atoms increases, the transmission rate of a single photon increases and the reflection rate decreases. In addition, by varying the phase difference and decay rate, the giant atoms are able to achieve perfect transmission and total reflection over the entire frequency range. We also find and show the conditions for the conversion of the optimal frequency. When the cumulative phase of photons reaches a certain value, the system can achieve perfect transmission, which is independent of frequency. This model of coupling giant atoms with waveguides has a promising application in quantum communication and quantum information processing. [ABSTRACT FROM AUTHOR]

G protein-coupled receptors (GPCRs) represent promising therapeutic targets due to their involvement in numerous physiological processes mediated by downstream G protein- and β-arrestin-mediated signal transduction cascades. Although the precise control of GPCR signaling pathways is therapeutically valuable, the molecular details for governing biased GPCR signaling remain elusive. The Angiotensin II type 1 receptor (AT1R), a prototypical class A GPCR with profound implications for cardiovascular functions, has become a focal point for biased ligand-based clinical interventions. Herein, we used single-molecule live-cell imaging techniques to evaluate the changes in stoichiometry and dynamics of AT1R with distinct biased ligand stimulations in real time. It was revealed that AT1R existed predominantly in monomers and dimers and underwent oligomerization upon ligand stimulation. Notably, β-arrestin-biased ligands induced the formation of higher-order aggregates, resulting in a slower diffusion profile for AT1R compared to G protein-biased ligands. Furthermore, we demonstrated that the augmented aggregation of AT1R, triggered by activation from each biased ligand, was completely abrogated in β-arrestin knockout cells. These findings furnish novel insights into the intricate relationship between GPCR aggregation states and biased signaling, underscoring the pivotal role of molecular behaviors in guiding the development of selective therapeutic agents. [ABSTRACT FROM AUTHOR]