A “Double-Multi” Model for Electromigration of Lithiums and Chlorides in ASR Affected Concrete

Existing reinforced concrete structures experience severe durability degradation when subjected to alkali– silica reaction (ASR) and chloride attack. A special electrochemical rehabilitation treatment, containing lithium compound anolyte, has been developed to drive lithium ions into concrete as well as remove chlorides simultaneously, for mitigating both the ASR-induced cracks and the chloride-induced corrosion. Good performance of introduced lithiums in controlling ASR-induced expansion has already been proved. Unfortunately, the migration mechanism of lithium in concrete under an external electric field is seldom investigated in existing literature. In this study, with help of the “double-multi” model, the efficiency of impregnation of lithium ions and simultaneously the removal of chloride ions through a specific electrochemical treatment are numerically evaluated, which results into the distribution profiles of all typical ionic species. The heterogeneous concrete model examines the aggregate effect, especially on the interaction with lithiums which are supposed to mitigate ASR. The ionic interaction between different species and the electrochemical reaction at electrodes are also considered. Through a relative thorough modelling of multi-phase and multi-species, a systemic parametric analysis based on a series of significant factors during electrochemical treatment (e.g., current density, treatment time, temperature, cathode position and concentration of lithium solution) reveals some important tendencies of ionic electromigration in concrete, which are supposed to guide the field application

MATH5 controls the acquisition of multiple retinal cell fates

Math5-null mutation results in the loss of retinal ganglion cells (RGCs) and in a concurrent increase of amacrine and cone cells. However, it remains unclear whether there is a cell fate switch of Math5-lineage cells in the absence of Math5 and whether MATH5 cell-autonomously regulates the differentiation of the above retinal neurons. Here, we performed a lineage analysis of Math5-expressing cells in developing mouse retinas using a conditional GFP reporter (Z/EG) activated by a Math5-Cre knock-in allele. We show that during normal retinogenesis, Math5-lineage cells mostly develop into RGCs, horizontal cells, cone photoreceptors, rod photoreceptors, and amacrine cells. Interestingly, amacrine cells of Math5-lineage cells are predominately of GABAergic, cholinergic, and A2 subtypes, indicating that Math5 plays a role in amacrine subtype specification. In the absence of Math5, more Math5-lineage cells undergo cell fate conversion from RGCs to the above retinal cell subtypes, and occasionally to cone-bipolar cells and Müller cells. This change in cell fate choices is accompanied by an up-regulation of NEUROD1, RXRγ and BHLHB5, the transcription factors essential for the differentiation of retinal cells other than RGCs. Additionally, loss of Math5 causes the failure of early progenitors to exit cell cycle and leads to a significant increase of Math5-lineage cells remaining in cell cycle. Collectively, these data suggest that Math5 regulates the generation of multiple retinal cell types via different mechanisms during retinogenesis

Bhlhb5 Regulates the Postmitotic Acquisition of Area Identities in Layers II-V of the Developing Neocortex

While progenitor-restricted factors broadly specify area identities in developing neocortex, the downstream regulatory elements involved in acquisition of those identities in post-mitotic neurons are largely unknown. Here, we identify Bhlhb5, a transcription factor expressed in layers II–V, as a post-mitotic regulator of area identity. Bhlhb5 is initially expressed in a high caudomedial to low rostrolateral gradient that transforms into a sharp border between sensory and rostral motor cortices. Bhlhb5-null mice exhibit aberrant expression of area-specific genes and structural organization in the somatosensory and caudal motor cortices. In somatosensory cortex, Bhlhb5-null mice display post-synaptic disorganization of vibrissal barrels. In caudal motor cortex, Bhlhb5-null mice exhibit anomalous differentiation of corticospinal motor neurons, accompanied by failure of corticospinal tract formation. Together, these results demonstrate Bhlhb5’s function as an area-specific transcription factor that regulates the post-mitotic acquisition of area identities and elucidate the genetic hierarchy between progenitors and post-mitotic neurons driving neocortical arealization.Stem Cell and Regenerative Biolog

Experimental realization of Bloch oscillations in a parity-time synthetic silicon photonic lattice

As an important electron transportation phenomenon, Bloch oscillations have been extensively studied in condensed matter. Due to the similarity in wave properties between electrons and other quantum particles, Bloch oscillations have been observed in atom lattices, photonic lattices, and so on. One of the many distinct advantages for choosing these systems over the regular electronic systems is the versatility in engineering artificial potentials. Here by utilizing dissipative elements in a CMOS-compatible photonic platform to create a periodic complex potential and by exploiting the emerging concept of parity-time synthetic photonics, we experimentally realize spatial Bloch oscillations in a non-Hermitian photonic system on a chip level. Our demonstration may have significant impact in the field of quantum simulation by following the recent trend of moving complicated table-top quantum optics experiments onto the fully integrated CMOS-compatible silicon platform

Paleotopography continues to drive surface to deep-layer interactions in a subtropical Critical Zone Observatory

This study was supported by the National Natural Science Foundation of China (grant No. 41571130051, No. 41771251 and No. 41977003), the National Key Research and Development Program of China (No. 2018YFE0107000) and the UK Natural Environmental Research Council (NE/N007611/1). We thank the individual authors of each study regarding critical zone research in the Red Soil CZO. We are grateful to Dong-Sheng Yu, Li-Gang Zhou, Shun-Hua Yang and Yue Zhao for their support in conducting the GPR survey. We are grateful to Qin-Bo Cheng for interpreting the radargram images. Data Availability: All radargram data, soil data and environmental predictors used in this study are available from the corresponding author upon request.Peer reviewedPostprin

BMP4 Cooperates with Retinoic Acid to Induce the Expression of Differentiation Markers in Cultured Mouse Spermatogonia

Spermatogenesis is sustained by the proliferation and differentiation of spermatogonial stem cells (SSCs). However, the molecules controlling these processes remain largely unknown. Here, we developed a simplified high concentration serum-containing system for the culture of mouse SSCs. Analysis of SSCs markers and transplantation results revealed that the cultured spermatogonia retained stem cell characteristics after long-term in vitro propagation. Using this culture system, the expression and function of bone morphogenetic protein 4 (BMP4) were explored. Immunostaining showed that BMP4 was predominantly expressed in germ cells and that its level increased as spermatogenesis progresses. BMP4 receptors BMPR1A and BMPRII were present in spermatogonia, spermatocytes, and round spermatids. Moreover, despite the mRNAs of these two genes being present in mouse Sertoli cells, only BMPRII was detected by using Western blotting assays. While exogenous BMP4 by itself did not induce the expression of Stra8 and c-Kit, two marker genes of differentiating spermatogonia, a significant cooperative effect of BMP4 and retinoic acid (RA) was observed. Moreover, pretreatment of cultured spermatogonia with the BMP4 antagonist Noggin could inhibit RA-induced expression of these two marker genes. In conclusion, BMP4 may exert autocrine effects and act cooperatively with RA to induce the differentiation of spermatogonia in vivo