Search

Direct asymmetric reductive amination provides a straightforward approach to preparing α-chiral amine synthons. We herein disclose a chemical process to produce α-chiral secondary amine from alkyl (hetero)aryl ketone, primary amine, and molecular hydrogen. By using high-throughput screening technology, an iridium/bisphosphine catalyst was selected that gives a turnover number of ∼1000 and a ee value of 91–92% in the production of (R)-2-((1-(2-(bis(4-methoxybenzyl)amino)pyridin-3-yl)ethyl)amino)ethan-1-ol (1). The formation of diastereomeric salt from the crude chiral amine with L-tartaric acid and crystallization upgrade the ee value to >99% and the purity to >99%. The multikilogram production of an enantiopure chiral secondary amine was realized with good reproducibility with this process.

Metastable binding sites (MBS) have been observed in a multitude of molecular dynamics simulations and can be considered low affinity allosteric binding sites (ABS) that function as stepping stones as the ligand moves toward the orthosteric binding site (OBS). Herein, we show that MBS can be utilized as ABS in ligand design, resulting in ligands with improved binding kinetics. Four homobivalent bitopic ligands (1–4) were designed by molecular docking of (S)-alprenolol ((S)-ALP) in the cocrystal structure of the β2adrenergic receptor (β2AR) bound to the antagonist ALP. Ligand 4displayed a potency and affinity similar to (S)-ALP, but with a >4-fold increase in residence time. The proposed binding mode was confirmed by X-ray crystallography of ligand 4in complex with the β2AR. This ligand design principle can find applications beyond the β2AR and G protein-coupled receptors (GPCRs) as a general approach for improving the pharmacological profile of orthosteric ligands by targeting the OBS and an MBS simultaneously.

Synergistic control of nitrogen oxides (NOx) and nitrogen-containing volatile organic compounds (NVOCs) from industrial furnaces is necessary. Generally, the elimination of n-butylamine (n-B), a typical pollutant of NVOCs, requires a catalyst with sufficient redox ability. This process induces the production of nitrogen-containing byproducts (NO, NO2, N2O), leading to lower N2selectivity of NH3selective catalytic reduction of NOx(NH3-SCR). Here, synergistic catalytic removal of NOxand n-B via spatially separated cooperative sites was originally demonstrated. Specifically, titania nanotubes supported CuOx–CeO2(CuCe–TiO2NTs) catalysts with spatially separated cooperative sites were creatively developed, which showed a broader active temperature window from 180 to 340 °C, with over 90% NOxconversion, 85% n-B conversion, and 90% N2selectivity. A synergistic effect of the Cu and Ce sites was found. The catalytic oxidation of n-B mainly occurred at the Cu sites inside the tube, which ensured the regular occurrence of the NH3-SCR reaction on the outer Ce sites under the matching temperature window. In addition, the n-B oxidation would produce abundant intermediate NH2*, which could act as an extra reductant to promote NH3-SCR. Meanwhile, NH3-SCR could simultaneously remove the possible NOxbyproducts of n-B decomposition. This novel strategy of constructing cooperative sites provides a distinct pathway for promoting the synergistic removal of n-B and NOx.

Trehalases (TREs) are pivotal enzymes involved in insect development and reproduction, making them prime targets for pest control. We investigated the inhibitory effect of three thiazolidinones with piperine skeletons (6a, 7b, and 7e) on TRE activity and assessed their impact on the growth and development of the fall armyworm (FAW), Spodoptera frugiperda. The compounds were injected into FAW larvae, while the control group was treated with 2% DMSO solvent. All three compounds effectively inhibited TRE activity, resulting in a significant extension of the pupal development stage. Moreover, the treated larvae exhibited significantly decreased survival rates and a higher incidence of abnormal phenotypes related to growth and development compared to the control group. These results suggest that these TRE inhibitors affect the molting of larvae by regulating the chitin metabolism pathway, ultimately reducing their survival rates. Consequently, these compounds hold potential as environmentally friendly insecticides.

Tailoring nanoscale catalysts to targeted applications is a vital component in reducing the carbon footprint of industrial processes; however, understanding and controlling the nanostructure influence on catalysts is challenging. Molybdenum disulfide (MoS2), a transition metal dichalcogenide (TMD) material, is a popular example of a nonplatinum-group-metal catalyst with tunable nanoscale properties. Doping with transition metal atoms, such as cobalt, is one method of enhancing its catalytic properties. However, the location and influence of dopant atoms on catalyst behavior are poorly understood. To investigate this knowledge gap, we studied the influence of Co dopants in MoS2nanosheets on catalytic hydrodesulfurization (HDS) through a well-controlled, ligand-directed, tunable colloidal doping approach. X-ray absorption spectroscopy and density functional theory calculations revealed the nonmonotonous relationship between dopant concentration, location, and activity in HDS. Catalyst activity peaked at 21% Co:Mo as Co saturates the edge sites and begins basal plane doping. While Co prefers to dope the edges over basal sites, basal Co atoms are demonstrably more catalytically active than edge Co. These findings provide insight into the hydrogenolysis behavior of doped TMDs and can be extended to other TMD materials.

Membrane protein structures are essential for the molecular understanding of diverse cellular processes and drug discovery. Detergents are not only widely used to extract membrane proteins from membranes but also utilized to preserve native protein structures in aqueous solution. However, micelles formed by conventional detergents are suboptimal for membrane protein stabilization, necessitating the development of novel amphiphilic molecules with enhanced protein stabilization efficacy. In this study, we prepared two sets of tandem malonate-derived glucoside (TMG) variants, both of which were designed to increase the alkyl chain density in micelle interiors. The alkyl chain density was modulated either by reducing the spacer length (TMG-Ms) or by introducing an additional alkyl chain between the two alkyl chains of the original TMGs (TMG-Ps). When evaluated with a few membrane proteins including a G protein-coupled receptor, TMG-P10,8 was found to be substantially more efficient at extracting membrane proteins and also effective at preserving protein integrity in the long term compared to the previously described TMG-A13. This result reveals that inserting an additional alkyl chain between the two existing alkyl chains is an effective way to optimize detergent properties for membrane protein study. This new biochemical tool and the design principle described have the potential to facilitate membrane protein structure determination.

Polymer nanocomposites combine the merits of polymer matrices and the unusual effects of nanoscale reinforcements and have been recognized as important members of the material family. Being a fundamental material property, thermal conductivity directly affects the molding and processing of materials as well as the design and performance of devices and systems. Polymer nanocomposites have been used in numerous industrial fields; thus, high demands are placed on the thermal conductivity feature of polymer nanocomposites. In this Perspective, we first provide roadmaps for the development of polymer nanocomposites with isotropic, in-plane, and through-plane high thermal conductivities, demonstrating the great effect of nanoscale reinforcements on thermal conductivity enhancement of polymer nanocomposites. Then the significance of the thermal conductivity of polymer nanocomposites in different application fields, including wearable electronics, thermal interface materials, battery thermal management, dielectric capacitors, electrical equipment, solar thermal energy storage, biomedical applications, carbon dioxide capture, and radiative cooling, are highlighted. In future research, we should continue to focus on methods that can further improve the thermal conductivity of polymer nanocomposites. On the other hand, we should pay more attention to the synergistic improvement of the thermal conductivity and other properties of polymer nanocomposites. Emerging polymer nanocomposites with high thermal conductivity should be based on application-oriented research.

Wide voltage range converters are significant for photovoltaic power generation system, battery charging, and auxiliary power source, etc. Resonant converter has been preferred topology for these applications, however, some demerits exist: 1) difficult to realize wide voltage gain range and low circulating current losses; 2) widely regulated switching frequency to adapt to wide voltage gain range; and 3) poor regulation at light load. Based on abovementioned shortcomings, dual resonance core-based step-up/down switched capacitor converter topology is presented in this article. Utilizing hybrid control strategy, nonoverlapping control strategy is used in the buck-type mode and overlapping control strategy is applied in the boost-type mode with common switching frequency range, and therefore, reduced frequency range in the presented converter is achieved. Moreover, wide voltage gain range can be obtained due to step-up/down capacity in the proposed converter. Furthermore, conversion ratio of proposed converter can be reduced to zero theoretically by using dual resonance core existed in the resonant switched capacitor converter. Finally, comprehensive operational principle analysis and performance analysis are provided, and a 48 to 28−90 V/100-W prototype is built to verify the analysis.

The integration of machine/deep learning and sensing technologies is transforming healthcare and medical practice. However, inherent limitations in healthcare data, namely scarcity, quality, and heterogeneity, hinder the effectiveness of supervised learning techniques which are mainly based on pure statistical fitting between data and labels. In this article, we first identify the challenges present in machine learning for pervasive healthcare and we then review the current trends beyond fully supervised learning that are developed to address these three issues. Rooted in the inherent drawbacks of empirical risk minimization that underpins pure fully supervised learning, this survey summarizes seven key lines of learning strategies, to promote the generalization performance for real-world deployment. In addition, we point out several directions that are emerging and promising in this area, to develop data-efficient, scalable, and trustworthy computational models, and to leverage multi-modality and multi-source sensing informatics, for pervasive healthcare.

G-protein-coupled receptors (GPCRs) activate heterotrimeric G proteins by promoting guanine nucleotide exchange. Here, we investigate the coupling of G proteins with GPCRs and describe the events that ultimately lead to the ejection of GDP from its binding pocket in the Gα subunit, the rate-limiting step during G-protein activation. Using molecular dynamics simulations, we investigate the temporal progression of structural rearrangements of GDP-bound Gsprotein (Gs·GDP; hereafter GsGDP) upon coupling to the β2-adrenergic receptor (β2AR) in atomic detail. The binding of GsGDPto the β2AR is followed by long-range allosteric effects that significantly reduce the energy needed for GDP release: the opening of α1-αF helices, the displacement of the αG helix and the opening of the α-helical domain. Signal propagation to the Gsoccurs through an extended receptor interface, including a lysine-rich motif at the intracellular end of a kinked transmembrane helix 6, which was confirmed by site-directed mutagenesis and functional assays. From this β2AR–GsGDPintermediate, Gsundergoes an in-plane rotation along the receptor axis to approach the β2AR–Gsemptystate. The simulations shed light on how the structural elements at the receptor–G-protein interface may interact to transmit the signal over 30 Å to the nucleotide-binding site. Our analysis extends the current limited view of nucleotide-free snapshots to include additional states and structural features responsible for signaling and G-protein coupling specificity.

Composite structures often experience various types of defects and damages during manufacturing, assembly, and service. In order to effectively restore the strength of damaged structures without compromising their original aerodynamic shape, adhesive repair is commonly employed. This paper investigates the tensile behavior of composite laminate. Initial tests include intact specimens, damaged specimens, and baseline scarf repair specimens. The load-carrying capacity and stiffness of the baseline repair specimens were both improved. Numerical analysis is developed based on the dimensions of the specimens. Numerical analysis model was established based on the dimensions of the specimens, employing continuum shell elements and cohesive elements to simulate the adhesive between the patch and the parent structure. The simulation results closely matched the experimental results, confirming the reliability of the simulation approach. Using this model as a basis, a parametric study is conducted on the patch repair parameters, including the scarf angle, the number of extra plies, and the overlapping width of extra plies. It is found that increasing the scarf angle and the overlap width of extra plies enhances the ultimate load capacity of the specimens, while increasing the number of extra plies improves the tensile stiffness. Subsequently, a scarf repair configuration with an angle of 1:50, an overlap width of 12.7 mm, and two extra plies is selected for the repair. Optimized scarf repair specimens are obtained and subjected to tensile testing. The results demonstrate that the optimized specimens exhibit excellent tensile performance, with an ultimate load reaching 93% of the intact specimens and a tensile stiffness in the linear range reaching 97% of the intact specimens.

The intracellular logistics system, consisting of vesicles, plays a crucial role in cellular transport. However, there is a lack of research on the types and functions of intracellular vesicles, and new technologies are needed for further investigation. Recently, researchers have discovered a new subcellular structure known as Dark-vacuole bodies. The composition, function, and potential synergy with other organelles of these Dark-vacuole bodies remain unclear. In this study, we utilized the high-resolution label-free Fourier ptychographic microscopy, developed by our research group, along with fluorescence confocal technology, to study and analyze Dark-vacuole bodies. Our findings provide evidence of the influence of Dark-vacuole bodies on the morphology, distribution, movement, and cell cycle of living cells. Specifically, we analyzed the effects of drug induced stimulation of lipid drops and endosomes, promotion of cell endocytosis, and induction of cellular senescence on Dark-vacuole bodies. Our results indicate that Dark-vacuole bodies show little correlation with lipid drops and endocytosis vesicles, but are significantly associated with late endosomes. Furthermore, cellular senescence leads to a significant increase in the number and size of Dark-vacuole bodies. This study serves as a foundation for further confirming the nature of Dark-vacuole bodies as new organelles.

Due to the long-distance communication and the limited resources, traditional full offloading algorithms cannot fully exploit radio and computation resources, which may cause more delays and higher energy consumption in mobile edge computing (MEC)-based vehicle-to-everything (V2X) networks. To solve this problem, a novel resource allocation (RA) algorithm with partial offloading for uplink multiuser MEC-based V2X networks is proposed. The optimization objective is to minimize the weighted sum of delays and energy consumption subject to the constraints on the delay requirements of tasks, communication distance, and the computation capability of roadside units. The formulated problem is non-convex and challenging to solve. To this end, an alternating optimization approach is designed to convert the original problem into three subproblems. A tabu search-based matching algorithm (TSM) is designed to solve the offloading object-selection subproblem. Then, a graph coloring algorithm is used to achieve channel allocation. Moreover, the computation RA subproblem is transformed into a convex optimization problem through variable substitution, and the suboptimal offloading ratios and computation RA coefficients are obtained. Simulation results show that the proposed algorithm achieves a lower total cost than the full offloading algorithm and the shortest distance matching algorithm.

G-protein-coupled receptors (GPCRs) are a class of integral membrane proteins that detect environmental cues and trigger cellular responses. Deciphering the functional states of GPCRs induced by various ligands has been one of the primary goals in the field. Here we developed an effective universal method for GPCR cryo-electron microscopy structure determination without the need to prepare GPCR-signaling protein complexes. Using this method, we successfully solved the structures of the β2-adrenergic receptor (β2AR) bound to antagonistic and agonistic ligands and the adhesion GPCR ADGRL3 in the apo state. For β2AR, an intermediate state stabilized by the partial agonist was captured. For ADGRL3, the structure revealed that inactive ADGRL3 adopts a compact fold and that large unusual conformational changes on both the extracellular and intracellular sides are required for activation of adhesion GPCRs. We anticipate that this method will open a new avenue for understanding GPCR structure‒function relationships and drug development.

NOxand CH3SH as two typical air pollutants widely coexist in various energy and industrial processes; hence, it is urgent to develop highly efficient catalysts to synergistically eliminate NOxand CH3SH. However, the catalytic system for synergistically eliminating NOxand CH3SH is seldom investigated to date. Meanwhile, the deactivation effects of CH3SH on catalysts and the formation mechanism of toxic byproducts emitted from the synergistic catalytic elimination reaction are still vague. Herein, selective synergistic catalytic elimination (SSCE) of NOxand CH3SH via engineering deep oxidation sites over Cu-modified Nb–Fe composite oxides supported on TiO2catalyst against toxic CO and HCN byproducts formation has been originally demonstrated. Various spectroscopic and microscopic characterizations demonstrate that the sufficient chemisorbed oxygen species induced by the persistent electron transfer from Nb–Fe composite oxides to copper oxides can deeply oxidize HCOOH to CO2for avoiding highly toxic byproducts formation. This work is of significance in designing superior catalysts employed in more complex working conditions and sheds light on the progress in the SSCE of NOxand sulfur-containing volatile organic compounds.

Tumor mutation burden (TMB) is a potential biomarker for evaluating the prognosis and response to immune checkpoint inhibitors, but its costly and time-consuming method of measurement limits its widespread application. This study aimed to identify the TMB-related histopathologic features from hematoxylin and eosin slides and explore their prognostic value in gliomas. TMB-related features were detected using a graph convolutional neural network from whole-slide images of patients from The Cancer Genome Atlas data set (619 patients), and the correlation between features and TMB was evaluated in an external validation set (237 patients). TMB-related features were used for predicting overall survival (OS) of patients to investigate whether these features have potential for prognostic prediction. Moreover, biological pathways underlying the prognostic value of the features were further explored. Histopathologic features derived from whole-slide images were significantly associated with patient TMB (P = 0.007 in the external validation set). TMB-related features showed excellent performance for OS prediction, and patients with lower-grade gliomas could be further stratified into different risk groups according to the features (P = 0.00013; hazard ratio, 4.004). Pathways involved in the cell cycle and execution of immune response were enriched in patients with higher OS risk. The TMB-related features could be used to estimate TMB and aid in prognostic risk stratification of patients with glioma with dysregulated biological pathways.

Chromatin relaxation is a prerequisite for the DNA repair machinery to access double-strand breaks (DSBs). Local histones around the DSBs then undergo prompt changes in acetylation status, but how the large demands of acetyl-CoA are met is unclear. Here, we report that pyruvate dehydrogenase 1α (PDHE1α) catalyzes pyruvate metabolism to rapidly provide acetyl-CoA in response to DNA damage. We show that PDHE1α is quickly recruited to chromatin in a polyADP-ribosylation-dependent manner, which drives acetyl-CoA generation to support local chromatin acetylation around DSBs. This process increases the formation of relaxed chromatin to facilitate repair-factor loading, genome stability and cancer cell resistance to DNA-damaging treatments in vitro and in vivo. Indeed, we demonstrate that blocking polyADP-ribosylation-based PDHE1α chromatin recruitment attenuates chromatin relaxation and DSB repair efficiency, resulting in genome instability and restored radiosensitivity. These findings support a mechanism in which chromatin-associated PDHE1α locally generates acetyl-CoA to remodel the chromatin environment adjacent to DSBs and promote their repair.

In visible light positioning systems, some scholars have proposed target tracking algorithms to balance the relationship among positioning accuracy, real-time performance, and robustness. However, there are still two problems: (1) When the captured LED disappears and the uncertain LED reappears, existing tracking algorithms may recognize the landmark in error; (2) The receiver is not always able to achieve positioning under various moving statuses. In this paper, we propose an enhanced visual target tracking algorithm to solve the above problems. First, we design the lightweight recognition/demodulation mechanism, which combines Kalman filtering with simple image preprocessing to quickly track and accurately demodulate the landmark. Then, we use the Gaussian mixture model and the LED color feature to enable the system to achieve positioning, when the receiver is under various moving statuses. Experimental results show that our system can achieve high-precision dynamic positioning and improve the system's comprehensive performance.

In this article, we investigate how multiple agents learn to coordinate to form efficient exploration in reinforcement learning. Though straightforward, independent exploration of the joint action space of multiple agents will become exponentially more difficult as the number of agents increases. To tackle this problem, we propose feudal latent-space exploration (FLE) for multi-agent reinforcement learning (MARL). FLE introduces a feudal commander to learn a low-dimensional global latent structure that instructs multiple agents to explore coordinately. Under this framework, the multi-agent policy gradient (PG) is adopted to optimize both the agent policy and latent structure end-to-end. We demonstrate the effectiveness of this method in two multi-agent environments that need explicit coordination. Experimental results validate that FLE outperforms baseline MARL approaches that use independent exploration strategy in terms of mean rewards, efficiency, and the expressiveness of coordination policies.

Catalyst deactivation caused by alkali metal poisoning has long been a key bottleneck in the application of selective catalytic reduction of NOxwith NH3(NH3–SCR), limiting the service life of the catalyst and increasing the cost of environmental protection. Despite great efforts, continuous accumulation of alkali metal deposition makes the resistance capacity of 2 wt % K2O difficult to enhance via merely loading acid sites on the surface, resulting in rapid deactivation and frequent replacement of the NH3–SCR catalyst. To further improve the resistance of alkali metals, encapsulating alkali metals into the bulk phase could be a promising strategy. The bottleneck of 2 wt % K2O tolerance has been solved by virtue of ultrahigh potassium storage capacity in the amorphous FePO4bulk phase. Amorphous FePO4as a support of the NH3–SCR catalyst exhibited a self-adaptive alkali-tolerance mechanism, where potassium ions spontaneously migrated into the bulk phase of amorphous FePO4and were anchored by PO43–with the generation of Fe2O3at the NH3–SCR reaction temperature. This ingenious potassium storage mechanism could boost the K2O resistance capacity to 6 wt % while maintaining approximately 81% NOxconversion. Besides, amorphous FePO4also exhibited excellent resistance to individual and coexistence of alkali (K2O and Na2O), alkali earth (CaO), and heavy metals (PbO and CdO), providing long durability for CePO4/FePO4catalysts in flue gas with multipollutants. The cheap and accessible amorphous FePO4paves the way for the development and implementation of poisoning-resistant NOxabatement.

Using adenine and metal ions to form secondary building units (SBUs), further connected by a highly symmetrical multicarboxylic linker to construct an amino-modified porous framework with high porosity, is an effective strategy. By regulating the deprotonation and hydrolysis capacity of the synthesized solvent, it is possible to obtain different charged frameworks. In this work, two stable anionic/neutral MOFs, (Et2NH2)[Zn3(TCPE)(adenine)2CH3COO]·DEF·3H2O (1) and [Zn3.5(adenine)(TCPE)1.5(DMA)(H2O)0.5]·2DMA·2H2O (2), have been synthesized based on zinc-adeninate building units and symmetric tetrakis(4-carboxyphenyl)ethylene (H4TCPE) in N,N-diethylformamide (DEF) and N,N-dimethylacetamide (DMA) reaction systems, respectively. 1is an anionic framework based on 1D rod zinc-adeninate SBU, containing 1D rectangular (14.3 × 6.3 Å2) and square (14.3 × 14.3 Å2) channels. While 2is a neutral framework built from isolated zinc-adeninate SBU, it contains hexagonal cages with a dimension of 5.5 Å in the structure. Both of them have high porosity (61.6% for 1and 46.3% for 2) and high stability in a wide range of pH. 1and 2show high C2H2adsorption capacity at 298 K (48.1 and 70.1 cm3g–1, respectively) and selective capacity for C2H2/CO2mixtures, which was confirmed by the breakthrough experiments. Furthermore, the interaction between the frameworks and gas molecules has also been explained by theoretical calculation. This work provides a good example of the design and regulation of porous structures for adsorption and separation functions.

In this paper, the formation mechanism of adhered debris on the surface of turned titanium alloy was studied. The adhesion rate of debris was calculated and evaluated using image extraction technology. The effects of cutting parameters and cooling conditions on the debris adhesion rate were also studied. Moreover, the chip temperature and trajectory in the turning process are analyzed using a finite element simulation and a thermal camera. The results show that there are three primary sources of adhered debris: the adhesion of the built-up edge, the micro-chips formed during the cutting process, and the micro-chips generated by the friction between the chip and the machined surface. In addition, the cutting speed is also one of the most significant factors affecting the adhesion of debris. The debris adhesion rate drops significantly as the cutting speed decreases. It was also found that the coolant can effectively reduce the debris adhesion rate, and this effect is more evident at low feed rates.

Accurate knowledge of the kinematics of the in vivo Ankle Joint Complex (AJC) is critical for understanding the biomechanical function of the foot and assessing postoperative rehabilitation of ankle disorders, as well as an essential guide to the design of ankle–foot assistant devices. However, detailed analysis of the continuous 3D motion of the tibiotalar and subtalar joints during normal walking throughout the stance phase is still considered to be lacking. In this study, dynamic radiographs of the hindfoot were acquired from eight subjects during normal walking. Natural motions with six Degrees of Freedom (DOF) and the coupled patterns of the two joints were analyzed. It was found that the movements of the two joints were mostly in opposite directions (including rotation and translation), mainly in the early and late stages. There were significant differences in the Range of Motion (ROM) in Dorsiflexion/Plantarflexion (D/P), Inversion/Eversion (In/Ev), and Anterior–Posterior (AP) and Medial–Lateral (ML) translation of the tibiotalar and subtalar joints (p< 0.05). Plantarflexion of the tibiotalar joint was coupled with eversion and posterior translation of the subtalar joint during the impact phase (R2= 0.87 and 0.86, respectively), and plantarflexion of the tibiotalar joint was coupled with inversion and anterior translation of the subtalar joint during the push-off phase (R2= 0.93 and 0.75, respectively). This coordinated coupled motion of the two joints may be a manifestation of the AJC to move flexibly while bearing weight and still have stability.

Parental histones, the carriers of posttranslational modifications, are deposited evenly onto the replicating DNA of sister chromatids in a process dependent on the Mcm2 subunit of DNA helicase and the Pole3 subunit of leading-strand DNA polymerase. The biological significance of parental histone propagation remains unclear. Here we show that Mcm2-mutated or Pole3-deleted mouse embryonic stem cells (ESCs) display aberrant histone landscapes and impaired neural differentiation. Mutation of the Mcm2 histone-binding domain causes defects in pre-implantation development and embryonic lethality. ESCs with biased parental histone transfer exhibit increased epigenetic heterogeneity, showing altered histone variant H3.3 and H3K27me3 patterning at genomic sites regulating differentiation genes. Our results indicate that the lagging strand pattern of H3.3 leads to the redistribution of H3K27me3 in Mcm2-2A ESCs. We demonstrate that symmetric parental histone deposition to sister chromatids contributes to cellular differentiation and development.

ABSTRACTIsothermal oxidation behaviour of two nickel base superalloys with different Cr contents was investigated in the temperature range of 700–800 °C. Weight–change curves show that weight loss increases with increasing temperature and a relatively lower Cr ratio corresponds to slow weight gain rate. Microscopic observations uncover that oxidation penetration attacks the alloys primarily along grain boundary especially for the lower-Cr alloy, and the penetration depth is strongly dependent on the oxidation temperature. The underlying oxidation mechanisms of the two alloys are explained using energy-dispersive x-ray spectroscopy and X-ray photoelectron spectroscopy.

The interphase of bicomponent fiber formed during co-extrusion is a key factor to influence the interfacial adhesion of the two components, which was not disclosed well by experiment or simulation. To simulate the interphase distribution which cannot be obtained by traditional interface boundary conditions, a mathematical model introducing the combined effects of diffusion and convection process was developed and the interphase thickness dependency nature of the extent of adhesion of bicomponent fiber was revealed visually. It was found that convection was the dominant effect on interphase formation at the low diffusion coefficient and the flow rate difference between the two components would facilitate the interphase development. Finally, the critical total flow rate of convection-dominated formation and diffusion-dominated formation of the interphase was found to be 2.0 × 10−4 kg/s. The interphase formation simulation was verified by experiment, which can provide an effective means for the study of interface control of bicomponent fiber.