DNMT3a in the hippocampal CA1 is crucial in the acquisition of morphine self‐administration in rats

Drug‐reinforced excessive operant responding is one fundamental feature of long-lasting addiction‐like behaviors and relapse in animals. However, the transcriptional regulatory mechanisms responsible for the persistent drug‐specific (not natural rewards) operant behavior are not entirely clear. In this study, we demonstrate a key role for one of the de novo DNA methyltransferase, DNMT3a, in the acquisition of morphine self‐administration (SA) in rats. The expression of DNMT3a in the hippocampal CA1 region but not in the nucleus accumbens shell was significantly up‐regulated after 1‐ and 7‐day morphine SA (0.3 mg/kg/infusion) but not after the yoked morphine injection. On the other hand, saccharin SA did not affect the expression of DNMT3a or DNMT3b. DNMT inhibitor 5‐aza‐2‐deoxycytidine (5‐aza) microinjected into the hippocampal CA1 significantly attenuated the acquisition of morphine SA. Knockdown of DNMT3a also impaired the ability to acquire the morphine SA. Overall, these findings suggest that DNMT3a in the hippocampus plays an important role in the acquisition of morphine SA and may be a valid target to prevent the development of morphine addiction. Includes Supplemental informatio

Fuzzy incremental control algorithm of loop heat pipe cooling system for spacecraft applications

AbstractReliable and high precision thermal control technologies are essential for the safe flight of advanced spacecraft. A fuzzy incremental control strategy is proposed for control of an LHP space cooling system comprising a loop heat pipe and a variable emittance radiator with MEMS louver. The generating and performing algorithm of the fuzzy control rules is provided with an analytical form based on the understanding of dynamics and control mechanisms of the space cooling system. This paper also presents a novel integrated mathematical model for the dynamic analysis of the LHP space cooling system and a numerical evaluation of the investigated control schemes. Numerical simulation results on the closed loop control effects suggest that the proposed control strategy takes advantage of no steady error, small overshoots and short settling times; thus benefiting safe, highly accurate and reliable operation of the entire space cooling system. The overshoots of the most important operating parameters (Tob, Qr, and P) under the proposed fuzzy incremental control have been reduced to 16.3%, 17.6% and 18.6% of the compared PID control’s, while the respective settling times have been shortened to 33.9%, 42.3% and 30.5% of the reference values

Atomic Defects in Two-Dimensioal Materials: From Single-Atom Spectroscopy to Functionalities in Opto-/Electronics, Nanomagnetism, and Catalysis

Two-dimensional layered graphene-like crystals including transition metal dichalcogenides (TMDs) have received extensive research interest due to their diverse electronic, valleytronic and chemical properties, with the corresponding optoelectronics and catalysis application being actively explored. However, the recent surge in two-dimensional materials science is accompanied by equally great challenges such as defects engineering in the large-scale sample synthesis. It is necessary to elucidate the effect of structural defects on the electronic properties, in order to develop an application-specific strategy for the defect engineering. Here in this paper, we review the two aspects of the existing knowledge of native defects in two-dimensional crystals. One is the point defects emerging in graphene and hexagonal boron nitride as probed by atomically resolved electron microscopy and their local electronic properties as measured by single-atom electron energy-loss spectroscopy. The other will focus on the point defects in TMDs and their influence on the electronic structure, photoluminescence and electric transport properties. Our review of atomic defects in two-dimensional materials will offer a clear picture of the defect physics involved to demonstrate the local modulation of the electronic properties and possibly benefit in potential applications in magnetism and catalysis

catena-Poly[[[triaqua­(4,5-diaza­fluorene-9-one)cadmium]-μ-benzene-1,3-dicarboxyl­ato] dihydrate]

In the title compound, {[Cd(C8H4O4)(C11H6N2O)(H2O)3]·2H2O}n, the CdII atom is seven-coordinated by two N atoms from the phenanthroline-derived 4,5-diaza­fluorene-9-one ligand, two O atoms from one bidentate benzene-1,3-dicarboxyl­ate ligand and three O atoms from the three water mol­ecules in a distorted penta­gonal-bipyramidal arrangement. Moreover, there are two dissociative water mol­ecules in each unit. Neighbouring units inter­act through π–π inter­actions [centroid–centroid distances = 3.325 (3) and 3.358 (4) Å] and O—H⋯O hydrogen-bonding, resulting in a two-dimensional network extending parallel to (001)

Layer-dependent anisotropic electronic structure of freestanding quasi-two dimensional MoS2

The anisotropy of the electronic transition is an important physical property not only determining the materials' optical property, but also revealing the underlying character of the electronic states involved. Here we used momentum-resolved electron energy-loss spectroscopy to study the evolution of the anisotropy of the electronic transition involving the low energy valence electrons in the free-standing MoS2 systems as the layer thickness was reduced to monolayer. We used the orientation and the spectral-density analysis to show that indirect to direct band-gap transition is accompanied by a three- to two-dimensional anisotropy cross-over. The result provides a logical explanation for the large sensitivity of indirect transition to the change of thickness compared with that for direct transition. By tracking the energy of indirect transition, we also revealed the asymmetric response of the valence band and conduction band to the quantum confinement effect. Our results have implication for future optoelectronic applications of atomic thin MoS2

Delving Deeper into Data Scaling in Masked Image Modeling

Understanding whether self-supervised learning methods can scale with unlimited data is crucial for training large-scale models. In this work, we conduct an empirical study on the scaling capability of masked image modeling (MIM) methods (e.g., MAE) for visual recognition. Unlike most previous works that depend on the widely-used ImageNet dataset, which is manually curated and object-centric, we take a step further and propose to investigate this problem in a more practical setting. Specifically, we utilize the web-collected Coyo-700M dataset. We randomly sample varying numbers of training images from the Coyo dataset and construct a series of sub-datasets, containing 0.5M, 1M, 5M, 10M, and 100M images, for pre-training. Our goal is to investigate how the performance changes on downstream tasks when scaling with different sizes of data and models. The study reveals that: 1) MIM can be viewed as an effective method to improve the model capacity when the scale of the training data is relatively small; 2) Strong reconstruction targets can endow the models with increased capacities on downstream tasks; 3) MIM pre-training is data-agnostic under most scenarios, which means that the strategy of sampling pre-training data is non-critical. We hope these observations could provide valuable insights for future research on MIM

Direct Imaging of Kinetic Pathways of Atomic Diffusion in Monolayer Molybdenum Disulfide

Direct observation of atomic migration both on and below surfaces is a long-standing but important challenge in materials science as diffusion is one of the most elementary processes essential to many vital material behaviors. Probing the kinetic pathways, including metastable or even transition states involved down to atomic scale, holds the key to the underlying physical mechanisms. Here, we applied aberration-corrected transmission electron microscopy (TEM) to demonstrate direct atomic-scale imaging and quasi-real-time tracking of diffusion of Mo adatoms and vacancies in monolayer MoS 2, an important two-dimensional transition metal dichalcogenide (TMD) system. Preferred kinetic pathways and the migration potential-energy landscape are determined experimentally and confirmed theoretically. The resulting three-dimensional knowledge of the atomic configuration evolution reveals the different microscopic mechanisms responsible for the contrasting intrinsic diffusion rates for Mo adatoms and vacancies. The new insight will benefit our understanding of material processes such as phase transformation and heterogeneous catalysis