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Titanium alloy (Ti-6Al-4V) is a difficult-to-machine material, known for its excellent physical and chemical properties. However, traditional machining methods incur high tool wear costs when processing this material. The near-dry electrical discharge milling (N-EDM) method, which removes excess material via electroerosion, mitigates the impact of titanium alloy’s hardness and strength, enabling effective material cutting. To enhance machining efficiency and surface quality, this study employs a simulation model of the inter-electrode flow field, combined with experimental data, to investigate the effect of milling thickness on key machining parameters and determine the optimal thickness. Subsequently, a four-factor, three-level (L 27 (4 3 )) orthogonal experiment was designed, with current, duty cycle, gas pressure, and atomization rate as input parameters. Material removal rate (MRR), relative electrode wear ratio (REWR), width of cut (WOC), and roughness average (R a ) were selected as primary optimization indicators. Based on the orthogonal experiment results, analysis of variance (ANOVA) was conducted to examine the influence of the input parameters on the various process indicators and determine the optimal single-objective processing parameters. Using Grey Relational Analysis (GRA), the multi-objective optimal machining parameters were identified as: 2 A current, 40% duty cycle, 0.2 MPa gas pressure, and 20 ml/min atomization rate. These parameters significantly enhance both processing efficiency and surface quality.

The human Immunodeficiency Centromeric Instability Facial Anomalies (ICF) 4 syndrome is a severe disease with increased mortality caused by mutation in the LSH gene. Although LSH belongs to a family of chromatin remodeling proteins, it remains unknown how LSH mediates its function on chromatin in vivo. Here, we use chemical-induced proximity to rapidly recruit LSH to an engineered locus and find that LSH specifically induces macroH2A1.2 and macroH2A2 deposition in an ATP-dependent manner. Tethering of LSH induces transcriptional repression and silencing is dependent on macroH2A deposition. Loss of LSH decreases macroH2A enrichment at repeat sequences and results in transcriptional reactivation. Likewise, reduction of macroH2A by siRNA interference mimicks transcriptional reactivation. ChIP-seq analysis confirmed that LSH is a major regulator of genome-wide macroH2A distribution. Tethering of ICF4 mutations fails to induce macroH2A deposition and ICF4 patient cells display reduced macroH2A deposition and transcriptional reactivation supporting a pathogenic role for altered marcoH2A deposition. We propose that LSH is a major chromatin modulator of the histone variant macroH2A and that its ability to insert marcoH2A into chromatin and transcriptionally silence is disturbed in the ICF4 syndrome. The human ICF 4 syndrome is caused by mutation of the chromatin remodeller LSH. Here, the authors show that LSH depletion disrupts the ability of histone variant macroH2A to insert into chromatin and silence transcription.

Electrochemical grinding (ECG) is processed by the combination of dissolution and grinding. It is very suitable for the processing of difficult-to-cut stainless steel, but its processing performance is restricted by the matching effect of dissolution and grinding. In this work, the processing of the torus surfaces of the stainless steel shaver cap was taken as the research object. A flow field model including the through-hole structure and the rotation of the grinding head was proposed to optimize the flow field distribution and promote the uniform dissolution of materials. The flow field simulation results showed that the rotational flow formed by the high-speed rotation prolonged the electrolyte flow path and was not conducive to the discharge of electrolytic products, and the reasonable selection of the diameter and distribution of the through-hole could reduce the velocity difference. The effects of rotational speed, feed rate, and inlet pressure on the flatness and surface roughness of the torus surfaces were experimentally investigated, and a better matching effect of dissolution and grinding was obtained. Moreover, the experimental results showed that the inner-jet ECG had a good prospect in the batch processing of high-hardness stainless steel parts.

The Immunodeficiency Centromeric Instability Facial Anomalies (ICF) 4 syndrome is caused by mutations in LSH/HELLS, a chromatin remodeler promoting incorporation of histone variant macroH2A. Here, we demonstrate that LSH depletion results in degradation of nascent DNA at stalled replication forks and the generation of genomic instability. The protection of stalled forks is mediated by macroH2A, whose knockdown mimics LSH depletion and whose overexpression rescues nascent DNA degradation. LSH or macroH2A deficiency leads to an impairment of RAD51 loading, a factor that prevents MRE11 and EXO1 mediated nascent DNA degradation. The defect in RAD51 loading is linked to a disbalance of BRCA1 and 53BP1 accumulation at stalled forks. This is associated with perturbed histone modifications, including abnormal H4K20 methylation that is critical for BRCA1 enrichment and 53BP1 exclusion. Altogether, our results illuminate the mechanism underlying a human syndrome and reveal a critical role of LSH mediated chromatin remodeling in genomic stability. LSH/HELLS is a chromatin remodeler promoting incorporation of histone variant macroH2A. Here the authors reveal a role for LSH in genome stability, in protecting nascent DNA at stalled forks mediated by macroH2A deposition and RAD51 filament formation.

We present the experimental realization of tunable honeycomb superlattice plasma photonic crystals (PPCs) in dielectric barrier discharge by utilizing mesh-liquid electrodes. Fast reconfiguration among the simple honeycomb lattice, honeycomb superlattice, and honeycomb-snowflake superlattice is achieved. A dynamic control on the sizes of center scattering elements in the honeycomb superlattice has been realized. A phenomenological activator-inhibitor reaction diffusion model is established to demonstrate the formation and reconstruction of the honeycomb superlattice. The simulations reproduce well the experimental observations. The photonic band diagrams of different honeycomb PPCs are studied by using the finite element method. The addition of large center elements in honeycomb superlattice yields remarkable omnidirectional band gaps that are about 2.5 times larger than in the simple honeycomb lattice. We propose an effective scheme to fabricate spatiotemporally controllable honeycomb lattices that enable great improvement in band gap size and dynamic control of microwave radiations for wide applications.

Phosphorus (P) deficiency is one of the most critical factors for plant growth and productivity, including its inhibition of lateral root initiation. Auxin response factors (ARFs) play crucial roles in root development via auxin signaling mediated by genetic pathways. In this study, we found that the transcription factor ZmARF1 was associated with low inorganic phosphate (Pi) stress-related traits in maize. This superior root morphology and greater phosphate stress tolerance could be ascribed to the overexpression of ZmARF1 . The knock out mutant zmarf1 had shorter primary roots, fewer root tip number, and lower root volume and surface area. Transcriptomic data indicate that ZmLBD1 , a direct downstream target gene, is involved in lateral root development, which enhances phosphate starvation tolerance. A transcriptional activation assay revealed that ZmARF1 specifically binds to the GC-box motif in the promoter of ZmLBD1 and activates its expression. Moreover, ZmARF1 positively regulates the expression of ZmPHR1 , ZmPHT1;2 , and ZmPHO2 , which are key transporters of Pi in maize. We propose that ZmARF1 promotes the transcription of ZmLBD1 to modulate lateral root development and Pi-starvation induced ( PSI ) genes to regulate phosphate mobilization and homeostasis under phosphorus starvation. In addition, ZmERF2 specifically binds to the ABRE motif of the promoter of ZmARF1 and represses its expression. Collectively, the findings of this study revealed that ZmARF1 is a pivotal factor that modulates root development and confers low-Pi stress tolerance through the transcriptional regulation of the biological function of ZmLBD1 and the expression of key Pi transport proteins.

Micro-dimple arrays with specific shapes and dimensions are crucial for reducing wear and vibration. Through-mask electrochemical machining (TMECM) using flexible cathodes removes materials based on anodic dissolution and allows for efficient processing of large-area micro-dimple arrays. However, the flexible cathode’s tight adherence to the mask can cause sludges from the processing area to stick or aggregate on the cathode surface, which can affect the processing localization of the micro-dimple array. This work introduces a method for TMECM using flexible cathodes which synchronizes the power switching with the cathode movement. Experiments on TMECM were conducted to investigate the changes in the distribution of sludges on the cathode surface. The processing time window for the adhesion and aggregation of sludges was identified. Moreover, the influences of sponge characteristics and processing parameters on micro-dimple machining were investigated. Rules governing the changes in micro-dimple diameter, depth, and bottom surface roughness concerning the sponge’s pore density, compression amount, power conduction time, and effective processing time were established. Ultimately, by adjusting the sponge characteristics and processing parameters, a high-precision micro-dimple array with a diameter of 229.6 ± 2 μm, a depth of 9 ± 0.3 μm, and a bottom surface roughness Sa of 0.34 μm and Ra of 0.43 μm was fabricated.

Deep narrow metal grooves have wide application prospects in the field of aeronautics and astronautics. Electrochemical machining (ECM) has a unique advantage in the fabrication of deep narrow grooves due to its advantages of no cutting heat, no cutting force, and high machining efficiency. But, there is significant stray current corrosion in the side wall of the deep narrow groove, which restricts the enhancement of the processing accuracy. In the interest of improving the processing accuracy of the deep narrow groove, the effects of compound feed and matching of pulse and oscillation (MOPAO) on the average current density distribution of the deep narrow groove side wall were studied based on finite element analysis (FEA) of the electrostatic field. The finite element simulation results show that the homogeneity of the deep narrow groove could be significantly improved with the increment of the oscillation amplitude, and the processing accuracy could be improved by prolonging the pulse turn-off time. Moreover, contrast experiments on the deep narrow groove ECM were carried out based on a self-developed ECM system. The experimental results indicate that the matching of pulse and oscillation can remarkably improve the processing accuracy, and smaller average groove width and better groove width uniformity can be obtained in comparison with the compound feed. Moreover, the maximum groove width is 2.78 mm, the minimum groove width is 2.73 mm, the length-width ratio reaches 11:1, and the depth-width ratio reaches 9:1 using the machining mode of MOPAO.

There are a large number of holes to be machined on aeroengine components such as blisks, casings, etc. In order to ensure position accuracy, these holes usually need to be drilled continuously in one process. To ensure the machining quality of holes, either replacing the cutting tools in advance leads to an increase in manufacturing costs, or adjusting process parameters leads to a decrease in production efficiency, which is difficult to meet the requirements of efficient and low-cost manufacturing. In response to this issue, this paper proposes a multi-objective optimization strategy for the process parameters of porous continuous drilling of superalloys alloys. A unified mathematical model for multi-objective optimization of drilling parameters has been established, and a tool life prediction model based on machining parameters and a machining process energy consumption model have been established as objective functions. The proposed optimization strategy can select different optimization strategies for different optimization objectives, including: maximum tool life, minimum machining energy consumption, and multi-objective drilling parameter optimization. Finally, experimental verification was conducted on the proposed strategy, and the results showed that the proposed optimization strategy can significantly reduce drilling processing energy consumption and increase the service life of drilling tools.