Human Primordial Germ Cells Are Specified from Lineage-Primed Progenitors.

In vitro gametogenesis is the process of making germline cells from human pluripotent stem cells. The foundation of this model is the quality of the first progenitors called primordial germ cells (PGCs), which in vivo are specified during the peri-implantation window of human development. Here, we show that human PGC (hPGC) specification begins at day 12 post-fertilization. Using single-cell RNA sequencing of hPGC-like cells (hPGCLCs) differentiated from pluripotent stem cells, we discovered that hPGCLC specification involves resetting pluripotency toward a transitional state with shared characteristics between naive and primed pluripotency, followed by differentiation into lineage-primed TFAP2A+ progenitors. Applying the germline trajectory to TFAP2C mutants reveals that TFAP2C functions in the TFAP2A+ progenitors upstream of PRDM1 to regulate the expression of SOX17. This serves to protect hPGCLCs from crossing the Weismann's barrier to adopt somatic cell fates and, therefore, is an essential mechanism for successfully initiating in vitro gametogenesis

Surface Modification of Ammonium Polyphosphate for Enhancing Flame-Retardant Properties of Thermoplastic Polyurethane.

Currently, the development of efficient and environmentally friendly flame-retardant thermoplastic polyurethane (TPU) composite materials has caused extensive research. Ammonium polyphosphate (APP) is used as a general intumescent flame retardant to improve the flame retardancy of TPU. In this paper, we developed a functionalized APP flame retardant (APP-Cu@PDA). Adding only 5 wt% of APP-Cu@PDA into TPU can significantly improve the flame-retardant’s performance of the composite material, reflected by a high LOI value of 28% with a UL-94 test of V-0 rating. Compared with pure TPU, the peak heat release rate, total heat release, peak smoke release rate, and total smoke release were reduced by 82%, 25%, 50%, and 29%, respectively. The improvements on the flame-retardant properties of the TPU/5%APP-Cu@PDA composites were due to the following explanations: Cu2+-chelated PDA has a certain catalytic effect on the carbonization process, which can promote the formation of complete carbon layers and hinder the transfer of heat and oxygen. In addition, after adding 5% APP-Cu@PDA, the tensile strength and elongation at the break of TPU composites did not decrease significantly. In summary, we developed a new flame-retardant APP-Cu@PDA, which has better flame-retardant properties than many reported TPU composites, and its preparation process is simple and environmentally friendly. This process can be applied to the industrial production of flame retardants in the future.post-print4370 K

Investigation of magnesium hydroxide functionalized by polydopamine/transition metal ions on flame retardancy of epoxy resin.

Aiming to impart epoxy resin (EP) with flame retardancy, magnesium hydroxide (MDH) was sequentially functionalized with four transition metals and polydopamine (PDA) to prepare MDH@M-PDA (M includes Fe3+, Co2+, Cu2+, Ni2+). Compared with MDH, MDH@M-PDA presented better dispersion in EP matrix. The results illustrated that a 30 mass% of MDH@Fe-PDA imparted the EP matrix with best fire retardancy and thermal stability. Specifically, the resultant EP/MDH/MDH@Fe-PDA composites remarkably reduced flammability, which is reflected by high LOI value of 29.3% and UL-94 V-0 ratings. The peak heat release rate (PHRR) and total smoke production (TSP) were reduced by 52% and 21%, respectively. Moreover, the impact and tensile strength of EP/MDH/MDH@M-PDA composites are improved compared with EP/MDH due to the better chemical compatibility of PDA in the EP matrix. Notably, this work provided a feasible design for organo-modified MDH and enriched its practical applications of MDH as functional fillers to polymers.post-print2133 K

Cross-Cultural Investigation of The Relation Between Attentional Disengagement and Reading Performance: Behavioral and Electrophysiological Evidence from Chinese and Italian

Developmental dyslexia is one of the most common learning disorders in children and adolescents. Revealing the causes of dyslexia is necessary for intervention on this disorder. Previous studies have shown that inefficient attention orienting is a causal factor for reading difficulties in dyslexics, and it can be indexed by sluggish inhibition of return. However, a fundamental understanding of the neural bases of inefficient attention disengagement remains unclear. The present thesis investigated the neural mechanism underlying the attention disengagement process and its relation with reading performance using behavioral and electrophysiological methods. Chapter 1 measured several electrophysiological indices while Chinese children, both dyslexic and typically developing, were asked to detect a target stimulus preceded by an uninformative cue stimulus in the classic cue-target paradigm. The possible relation between stimulus-locked ERP activity and reading skills was also examined to further understand how efficiency of attention disengagement affects reading. These studies considered both cue-locked and target-locked ERP activities to examine the neural mechanism of attention disengagement. Chapter 2 examined neural oscillations related to attention disengagement as well as resting-state EEG activity in different frequency ranges in children with and without dyslexia. The relation between activation patterns in several frequency ranges and reading skills indicated that neural indices of attention disengagement and resting-state activity are predictive of reading performance. In the following Chapters 3 and 4, the neural mechanisms underlying attention disengagement was investigated in Italian young adults. Chapter 3 investigated both cue-evoked and target-evoked ERP activities in the cue-target task, and also examined the correlation between neural cueing effect, attention disengagement efficiency, and reading skills. In Chapter 4, neural oscillations related to target-evoked as well as resting-state EEG activity in different frequency ranges were examined on the Italian young adults, to provide a new insight on the correlation between neural oscillations in stimulus-locked activity and reading performance. Overall, these studies revealed the different electrophysiological parameters indexing the efficiency of attention disengagement for both children and adults, providing multiple signatures of stimulus-locked neural activity during attention shifting. Importantly, the parallel results from Chinese and Italian participants shows the generality of these findings and demonstrates the influence of attention shifting mechanisms on reading performance in both alphabetic and logographic scripts. More importantly, this study suggests that intervention targeting attention disengagement efficiency might be a fruitful approach for improving reading skills in dyslexia.Developmental dyslexia is one of the most common learning disorders in children and adolescents. Revealing the causes of dyslexia is necessary for intervention on this disorder. Previous studies have shown that inefficient attention orienting is a causal factor for reading difficulties in dyslexics, and it can be indexed by sluggish inhibition of return. However, a fundamental understanding of the neural bases of inefficient attention disengagement remains unclear. The present thesis investigated the neural mechanism underlying the attention disengagement process and its relation with reading performance using behavioral and electrophysiological methods. Chapter 1 measured several electrophysiological indices while Chinese children, both dyslexic and typically developing, were asked to detect a target stimulus preceded by an uninformative cue stimulus in the classic cue-target paradigm. The possible relation between stimulus-locked ERP activity and reading skills was also examined to further understand how efficiency of attention disengagement affects reading. These studies considered both cue-locked and target-locked ERP activities to examine the neural mechanism of attention disengagement. Chapter 2 examined neural oscillations related to attention disengagement as well as resting-state EEG activity in different frequency ranges in children with and without dyslexia. The relation between activation patterns in several frequency ranges and reading skills indicated that neural indices of attention disengagement and resting-state activity are predictive of reading performance. In the following Chapters 3 and 4, the neural mechanisms underlying attention disengagement was investigated in Italian young adults. Chapter 3 investigated both cue-evoked and target-evoked ERP activities in the cue-target task, and also examined the correlation between neural cueing effect, attention disengagement efficiency, and reading skills. In Chapter 4, neural oscillations related to target-evoked as well as resting-state EEG activity in different frequency ranges were examined on the Italian young adults, to provide a new insight on the correlation between neural oscillations in stimulus-locked activity and reading performance. Overall, these studies revealed the different electrophysiological parameters indexing the efficiency of attention disengagement for both children and adults, providing multiple signatures of stimulus-locked neural activity during attention shifting. Importantly, the parallel results from Chinese and Italian participants shows the generality of these findings and demonstrates the influence of attention shifting mechanisms on reading performance in both alphabetic and logographic scripts. More importantly, this study suggests that intervention targeting attention disengagement efficiency might be a fruitful approach for improving reading skills in dyslexia

Development of Trans-1,4-Polyisoprene Shape-Memory Polymer Composites Reinforced with Carbon Nanotubes Modified by Polydopamine

In this study, which was inspired by mussel-biomimetic bonding research, carbon nanotubes (CNTs) were interfacially modified with polydopamine (PDA) to prepare a novel nano-filler (CNTs@PDA). The structure and properties of the CNTs@PDA were studied using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The CNTs and the CNTs@PDA were used as nanofillers and melt-blended into trans-1,4 polyisoprene (TPI) to create shape-memory polymer composites. The thermal stability, mechanical properties, and shape-memory properties of the TPI/CNTs and TPI/CNTs@PDA composites were systematically studied. The results demonstrate that these modifications enhanced the interfacial interaction, thermal stability, and mechanical properties of TPI/CNTs@PDA composites while maintaining shape-memory performance

Resting-state EEG reveals global network deficiency in dyslexic children

Developmental dyslexia is known to involve dysfunctions in multiple brain regions; however, a clear understanding of the brain networks behind this disorder is still lacking. The present study examined the functional network connectivity in Chinese dyslexic children with resting-state electroencephalography (EEG) recordings. EEG data were recorded from 27 dyslexic children and 40 age-matched controls, and a minimum spanning tree (MST) analysis was performed to examine the network connectivity in the delta, theta, alpha, and beta frequency bands. The results show that, compared to age-matched controls, Chinese dyslexic children had global network deficiencies in the beta band, and the network topology was more path-like. Moderate correlations are observed between MST degree metric and rapid automatized naming and morphological awareness tests. These observations, together with the findings in alphabetic languages, show that brain network deficiency is a common neural underpinning of dyslexia across writing systems

Eccentricity and obliquity paced carbon cycling in the Early Triassic and implications for post-extinction ecosystem recovery.

The timing of marine ecosystem recovery following the End Permian Mass Extinction (EPME) remains poorly constrained given the lack of radiometric ages. Here we develop a high-resolution carbonate carbon isotope (δ(13)Ccarb) record for 3.20 million years of the Olenekian in South China that defines the astronomical time-scale for the critical interval of major evolutionary and oceanic events in the Spathian. δ(13)Ccarb documents eccentricity modulation of carbon cycling through the period and a strong obliquity signal. A shift in phasing between short and long eccentricity modulation, and amplification of obliquity, is nearly coincident with a 2% decrease in seawater δ(13)CDIC, the last of a longer-term stepped decrease through the Spathian. The mid-Spathian shift in seawater δ(13)CDIC to typical thermocline values is interpreted to record a major oceanic reorganization with global climate amelioration. Coincidence of the phasing shift with the first occurrence of marine reptiles (248.81 Ma), suggests that their invasion into the sea and the onset of a complex ecosystem were facilitated by restoration of deep ocean ventilation linked mechanistically to a change in the response of the oceanic carbon reservoir to astronomical forcing. Together these records place the first constraints on the duration of the post-extinction recovery to 3.35 myr

Bio-based flame retardants to polymers: A review

Due to environmental concerns, some of the conventional halogenated flame retardants have been banned. In this context, both the industrial and academics have made efforts to develop more eco-friendly and sustainable flame retardant materials. Among new flame retardants, bio-based groups have attracted plenty of attention. In this review, varied types of bio-based flame retardants are systematically described, including the structural characteristics, flame retardant behaviors, and an overview of flame retardant mechanism. Recent research progress on various bio-based materials such as flame retardants (e.g., chitosan, lignin, phytic acid, polydopamine, Tannic acid, β-cyclodextrin, etc.) applied to different polymers are adequately summarized. Finally, the opportunities and challenges for the future development of bio-based flame retardants are briefly outlooked