Treatment of Donor Cells with Oxidative Phosphorylation Inhibitor CPI Enhances Porcine Cloned Embryo Development.

Somatic cell nuclear transfer (SCNT) technology holds great promise for livestock industry, life science and human biomedicine. However, the development and application of this technology is limited by the low developmental potential of SCNT embryos. The developmental competence of cloned embryos is influenced by the energy metabolic status of donor cells. The purpose of this study was to investigate the effects of CPI, an oxidative phosphorylation inhibitor, on the energy metabolism pathways of pig fibroblasts and the development of subsequent SCNT embryos. The results showed that treatment of porcine fibroblasts with CPI changed the cellular energy metabolic pathways from oxidative phosphorylation to glycolysis and enhanced the developmental ability of subsequent SCNT embryos. The present study establishes a simple, new way to improve pig cloning efficiency, helping to promote the development and application of pig SCNT technology.

Protein Dynamic Landscape during Mouse Mammary Gland Development from Virgin to Pregnant, Lactating, and Involuting Stages.

The mammary gland undergoes significant physiological changes as it undergoes a transition from virgin to pregnancy, lactation, and involution. However, the dynamic role of proteins in regulating these processes during mouse mammary gland development has not been thoroughly explored. In this study, we collected mouse mammary gland tissues from mature virgins aged 8-10 weeks (V), day 16 of pregnancy (P16d), day 12 of lactation (L12d), day 1 of forced weaning (FW 1d), and day 3 of forced weaning (FW 3d) stages for analysis using DIA-based quantitative proteomics technology. A total of 3,312 proteins were identified, of which 843 were DAPs that were categorized into nine clusters based on their abundance changes across developmental stages. Notably, DAPs in cluster 2, which peaked at the L12d stage, were primarily associated with mammary gland development and lactation. The protein-protein interaction network revealed that the epidermal growth factor (EGF) was central to this cluster. Our study provides a comprehensive overview of the mouse mammary gland development proteome and identifies some important proteins, such as EGF, Janus kinase 1 (JAK1), and signal transducer and activator of transcription 6 (STAT6) that may serve as potential targets for future research to provide guidelines for a deeper understanding of the developmental biology of mammary glands.

Information Difference of Transfer Entropies between Head Motion and Eye Movement Indicates a Proxy of Driving.

Visual scanning is achieved via head motion and gaze movement for visual information acquisition and cognitive processing, which plays a critical role in undertaking common sensorimotor tasks such as driving. The coordination of the head and eyes is an important human behavior to make a key contribution to goal-directed visual scanning and sensorimotor driving. In this paper, we basically investigate the two most common patterns in eye-head coordination: "head motion earlier than eye movement" and "eye movement earlier than head motion". We utilize bidirectional transfer entropies between head motion and eye movements to determine the existence of these two eye-head coordination patterns. Furthermore, we propose a unidirectional information difference to assess which pattern predominates in head-eye coordination. Additionally, we have discovered a significant correlation between the normalized unidirectional information difference and driving performance. This result not only indicates the influence of eye-head coordination on driving behavior from a computational perspective but also validates the practical significance of our approach utilizing transfer entropy for quantifying eye-head coordination.

Investigations of Micro-Deformation in Monocrystalline Copper at Low Temperatures via Indentation.

Indentation experiments on differently oriented faces of monocrystalline copper were conducted to investigate the micro-deformation process at temperatures ranging from room temperature to 150 K. The morphologies and textures of the residual imprints were observed using electron microscopy. Distinct slip bands were observed inside the imprints at 150 K compared to smooth surfaces at room temperature. Molecular dynamics simulations were performed to identify the deformation process beneath the indentation region. The results showed that plastic deformation was inhibited with decreasing temperature, but elastic recovery during the unloading process was enhanced, resulting in inner slip bands (ISBs) being observable in the residual imprints. The performances of these ISBs were strongly associated with the angles between the indentation direction and major slip surfaces and could be considered microscopic forms on the surfaces of aggregated geometrically necessary dislocations (GNDs). This work helped reveal the micro-deformation mechanism of indentations inside imprints.

Temperature-Induced Internal Stress Influence on Specimens in Indentation Tests.

The factors affecting the internal stress of specimens during indentation tests were investigated by finite element analysis (FEA) modelling. This was carried out to gain a qualitative understanding of the test errors introduced by the temperature environment during the indentation process. In this study, the influence of thermal expansion of fixed stage on upper specimen (currently neglected in temperature indentation) was explored in detail. Technical issues associated with the parameters of the specimen (such as thickness, width, and elastic modulus) and external conditions (such as stage and glue) were identified and addressed. The test error of the calculated hardness and elastic modulus of the specimen reached up to more than 3% simultaneously at -196 °C (temperature of liquid nitrogen). Based on these considerations, the preferred operation conditions were identified for testing in specific temperature environment. These results can guide experiments aimed at obtaining precise mechanical parameters.

Atomic investigations on the tension-compression asymmetry of AlxFeNiCrCu (x = 0.5, 1.0, 1.5, 2.0) high-entropy alloy nanowires.

The tension and compression of high-entropy alloy (HEA) nanowires (NWs) are remarkably asymmetric, but the micro mechanism is still unclear. In this research, the tension-compression asymmetry of AlxFeNiCrCu HEA NWs (x = 0.5, 1.0, 1.5, 2.0) was quantitatively characterized via molecular dynamics simulations, focusing on the influences of the NW diameter, the Al content, the crystalline orientation, and the temperature, which are significant for applying HEAs in nanotechnology. The increased NW diameter improves the energy required for stacking faults nucleating, thus strengthening AlFeNiCrCu HEA NWs. A few twins during stretching weaken the strengthening effects, thereby decreasing the tension-compression asymmetry. The increased Al content raises the tension-compression asymmetry by promoting the face-centered cubic to body-centered cubic phase transition during stretching. The tension along the [001] crystalline orientation is stronger than the compression, while the [110] and [111] crystalline orientations are entirely the opposite, and the tension-compression asymmetry along the [111] crystalline orientation is the minimum. The diversities in the tension-compression asymmetry depend on the deformation mechanism. Compressing along the [001] crystalline orientation and stretching along the [110] crystalline orientation induces twinning. Deformation along the [111] crystalline orientation only leaves stacking faults in the NWs. Therefore, the tension and compression along the [111] crystalline orientation exhibit minimal asymmetry. As the temperature rises, the tension-compression asymmetry along the [001] and [111] crystalline orientations increases, while that along the [110] crystalline orientation decreases.

Influence of pia-arachnoid complex on the indentation response of porcine brain at different length scales.

Brain tissues are surrounded by two tightly adhering thin membranes known as the pia-arachnoid complex (PAC), which is pivotal in regulating brain mechanical response upon mechanical impact. Despite the crucial role of PAC as a structural damper protecting the brain, its mechanical contribution has received minimal attention. In this work, the mechanical contribution of PAC on brain tissues against mechanical loading is characterized by using a custom-built indentation apparatus. The indentation responses of the isolated and PAC-overlaid brains are quantitatively compared at different length scales and strain rates. Results show that PAC substantially affects the indentation response of brain tissues at micro- and macro-scales and provides better protection against mechanical impact at a relatively small (µm) length scale. The modulus of the PAC-overlaid brain shows a threefold stiffening at the microscale compared with that of the isolated brain (with instantaneous shear modulus distribution means of 0.85 ± 0.14 kPa versus 2.64 ± 0.43 kPa at the strain rate of 0.64 s-1 and 1.40 ± 0.31 kPa versus 4.02 ± 0.51 at 1.27 s-1). These findings indicate that PAC seriously affects the mechanical response of brain tissues, especially at the microscale, and may have important implications for the studies of brain injury.

A new scaling number reveals droplet dynamics on vibratory surfaces.

HYPOTHESIS: Droplet spreading on surfaces is a ubiquitous phenomenon in nature and is relevant with a wide range of applications. In practical scenarios, surfaces are usually associated with certain levels of vibration. Although vertical or horizontal modes of vibration have been used to promote droplet dewetting, bouncing from immiscible medium, directional transport, etc., a quantitative understanding of how external vibration mediates the droplet behaviors remains to be revealed. METHODS: We studied droplets impacting on stationary and vibratory surfaces, respectively. In analogy to the Weber number We=ρUi2D0/γ, we define the vibration Weber number We*=ρUv2D0/γ to quantitively analyze the vibration-induced dynamic pressure on droplet behaviors on vibratory surfaces, where ρ,γ,D0,UiandUv are liquid density, surface tension, initial droplet diameter, impact velocity of the droplet, and velocity amplitude of vibration, respectively. FINDINGS: We demonstrate that the effect of vibration on promoting droplet spreading can be captured by a new scaling number expressed as We*/[We1\2sin(θ/2)], leading to (Dm - Dm0)/Dm0 âˆ We*/[We1\2sin(θ/2)], where θ is the contact angle, and Dm0 and Dm are the maximum diameter of the droplet on stationary and vibratory surfaces, respectively. The scaling number illustrates the relative importance of vibration-induced dynamic pressure compared to inertial force and surface tension. Together with other well-established non-dimensional numbers, this scaling number provides a new dimension and framework for understanding and controlling droplet dynamics. Our findings can also find applications such as improving the power generation efficiency, intensifying the deposition of paint, and enhancing the heat transfer of droplets.

Molecular dynamics investigations of the size effects on mechanical properties and deformation mechanism of amorphous and monocrystalline composite AlFeNiCrCu high-entropy alloy nanowires.

The atomic models of amorphous and monocrystalline composite AlFeNiCrCu high-entropy alloy nanowires were established via the molecular dynamics method. The effects of amorphous structure thickness on mechanical properties and deformation mechanism were investigated by applying tensile and compressive loads to the nanowires. As the thickness of amorphous structures increases, the tensile yield strength decreases, and the asymmetry between tension and compression decreases. The tensile deformation mechanism transforms from the coupling interactions between stacking faults in crystal structures and uniform deformation of amorphous structures to the individual actions of uniform deformation of amorphous structures. During the tensile process, the nanowires necking appears at amorphous structures, and the thinner amorphous structures, the more prone to necking. The compressive deformation mechanism is the synergistic effects of twins and SFs in crystal structures and uniform deformation of amorphous structures, which is irrelevant to amorphous structure thickness. Remarkably, amorphous structures transform into crystal structures in the amorphous and monocrystalline composite nanowires during the compressive process.

Low Temperature Nanoindentation: Development and Applications.

Nanoindentation technique at low temperatures have developed from initial micro-hardness driving method at a single temperature to modern depth-sensing indentation (DSI) method with variable temperatures over the last three decades. The technique and implementation of representative cooling systems adopted on the indentation apparatuses are discussed in detail here, with particular emphasis on pros and cons of combination with indentation technique. To obtain accurate nanoindentation curves and calculated results of material properties, several influence factors have been carefully considered and eliminated, including thermal drift and temperature induced influence on indenter and specimen. Finally, we further show some applications on typical materials and discuss the perspectives related to low temperature nanoindentation technique.

Mechanical Behavior of Undoped n-Type GaAs under the Indentation of Berkovich and Flat-Tip Indenters.

In this research, the mechanical behavior of undoped n-type GaAs was investigated by nanoindentation experiments using two types of indenters-Berkovich and flat-tip-with force applied up to 1000 mN. From the measured force-depth curves, an obvious pop-in phenomenon occurred at force of 150 mN with the flat-tip indenter representing elastic-plastic transition. The Young's modulus and hardness of GaAs were calculated to be 60-115 GPa and 6-10 GPa, respectively, under Berkovich indenter. Based on the observation of indent imprints, the fracture characteristics of GaAs were also discussed. A recovery of crack by the next indentation was observed at 1000 mN with Berkovich indenter. In the case of flat-tip indentation, however, surface material sank into a wing shape from 400 mN. In this sinking region, a density of fork-shaped sinking, slip lines, and crossed pits contributed to the slip bands, and converging crossed twinning deformations inside the GaAs material were generated. Since cracks and destructions on GaAs surface took place more easily under the flat-tip indentation than that of Berkovich, a machining tool with a sharp tip is recommended for the mechanical machining of brittle materials like GaAs.

Design and testing of a cryogenic indentation apparatus.

A modularized cryogenic indentation apparatus was designed and created to study the deformation mechanisms and mechanical properties of materials at low temperatures. The indentation process is actuated by piezoelectric stack and flexure hinge, and the entire mechanical module is kept inside the vacuum chamber to prevent the occurrence of ice. Numerous issues including the effects of the application of cooling module and processes to diminish the temperature effect on the indentation tip were addressed. Several influential factors during temperature indentation were discussed. Tests on calibration specimen demonstrated the feasibility of the apparatus. Monocrystalline silicon and copper were tested using the current apparatus at temperatures ranging from room temperature to 150 K to show its main functions and usability.

Investigations of Phase Transformation in Monocrystalline Silicon at Low Temperatures via Nanoindentation.

Nanoindentations of monocrystalline silicon are conducted to investigate the phase transformation process at a temperature range from 292 K to 210 K. The load-displacement curves are obtained and the residual indents are detected by Raman spectra. MD simulations are also conducted to identify the phase state during nanoindentation. The results show that the low temperature has no influence on the generation of Si-II during loading process of indentation, but the phenomenon of pop-out is inhibited with the temperature decreasing. The probability of pop-out occurrence has a dramatic drop from 260 K to 230 K. Both the generation and propagation of Si-III/XII transformed from Si-II are inhibited by the low temperature, and only a-Si was generated as a final phase state.

[The suppression of melatonin on mouse oocyte in vitro maturation of mouse].

AIM: To study whether melatonin has effect on oocyte maturation of mouse in vitro. METHODS: Mouse oocytes were cultured in maturation medium, HX-medium, or HX-medium supplemented with FSH, and the effects of MT on meiotic maturation of mouse oocyte were examined. RESULTS: (1) MT at all doses of 0.1 g/L, 0.02 g/L, 0.4 g/L or 0.8 g/L inhibited the formation of PB1 in CEO cultured in maturation medium and had no effect on GVBD. (2) MT could delay GVBD and the extrusion of PB1 in CEOs of mouse oocytes by dynamic curves. In contrast to the control, GVBD and PB1 extrusion of oocytes in the treated groups had been delayed by 8-10 hours and 3-4 hours respectively. (3) MT inhibited the effect of FSH on resumption of meiosis, but no effect on the formation of PB1. (4) MT and HX had cooperation effects on spontaneous oocyte maturation in CEO, but not in DO. CONCLUSION: MT is able to affect mouse oocyte maturation and the regulation mechanisms may be related to cumulus cells.