24 research outputs found
A phase transition driven by subtle distortion without broken symmetry on spin, charge and lattice in Layered LnCu4-{\delta}P2(Ln=Eu, Sr)
In the scenario of Landau phase transition theory in condensed matter
physics, any thermal dynamic phase transition must be subject to some kind of
broken symmetries, that are relative to its spin, charge, orbital and lattice.
Here we report a rare phase transition at Tp ~120 K or 140 K in layered
materials LnCu4-{\delta}P2 (Ln=Eu, Sr) driven by a subtle structural-distortion
without any broken symmetry on charge, spin and lattice. The variations of the
lattice parameters, ({\Delta}Lc/Lc) ~ 0.013% or 0.062%, verified by thermal
expansion, is much less than that for a typical crystalline phase transition
(~0.5-1%), but the significant anomaly in heat capacity provides clear evidence
of its intrinsic nature of thermodynamic transition.Comment: 13 pages, 4 figure
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A solution-processable and ultra-permeable conjugated microporous thermoset for selective hydrogen separation.
The synthesis of a polymer that combines the processability of plastics with the extreme rigidity of cross-linked organic networks is highly attractive for molecular sieving applications. However, cross-linked networks are typically insoluble or infusible, preventing them from being processed as plastics. Here, we report a solution-processable conjugated microporous thermoset with permanent pores of ~0.4 nm, prepared by a simple heating process. When employed as a two-dimensional molecular sieving membrane for hydrogen separation, the membrane exhibits ultrahigh permeability with good selectivity for H2 over CO2, O2, N2, CH4, C3H6 and C3H8. The combined processability, structural rigidity and easy feasibility make this polymeric membrane promising for large-scale hydrogen separations of commercial and environmental relevance
Serum, spleen metabolomics and gut microbiota reveals effect of catalpol on blood deficiency syndrome caused by cyclophosphamide and acetylphenylhydrazine
Catalpol (CA), extracted from Rehmannia Radix, holds extensive promise as a natural medicinal compound. This study employed 16S rRNA gene sequencing and combined serum and spleen metabolomics to profoundly investigate the therapeutic effects of CA on blood deficiency syndrome (BDS) and the underlying mechanisms. Notably, CA exhibited effectiveness against BDS induced by cyclophosphamide (CP) and acetylphenylhydrazine (APH) in rats-CA substantially elevated levels of crucial indicators such as erythropoietin (EPO), granulocyte colony-stimulating factor (G-CSF), tumor necrosis factor-alpha (TNF-a), and interleukin-6 (IL-6). Additionally, CA could alleviate peripheral blood cytopenia. Furthermore, the analysis of 16S rRNA revealed that CA had the potential to reverse the Firmicutes/Bacteroidetes (F/B) ratio associated with BDS. Through comprehensive serum and spleen metabolomic profiling, we successfully identified 22 significant biomarkers in the serum and 23 in the spleen, respectively. Enrichment analysis underscored Glycerophospholipid metabolism and Sphingolipid metabolism as potential pathways through which CA exerts its therapeutic effects on BDS
Magnetic Domain Structure in Ferromagnetic Kagome Metal DyMn6Sn6
Two types of magnetic domains, that is, type-I domain belt domain and type-II new stripe domain, are observed in a kagome metal DyMn6Sn6 by microscopic magneto-optic Kerr imaging technique. From 255 to 235Â K, the spin reorientation is observed directly in DyMn6Sn6. We analyze the structure of two types of domains through brightness distribution of the images. The type-II domain exists from 235 to 160Â K by zero-field cooling (ZFC). At the same time, type-I domain and type-II domain coexist and transform into each other with variation of temperature. Type-II domains can easily transform into type-I domains when the temperature and magnetic field changes, and this process is irreversible. These results demonstrate that the type-I domain is more stable than the type-II domain. The phase diagram of magnetic domains in DyMn6Sn6 is obtained
Secrets of RLHF in Large Language Models Part I: PPO
Large language models (LLMs) have formulated a blueprint for the advancement
of artificial general intelligence. Its primary objective is to function as a
human-centric (helpful, honest, and harmless) assistant. Alignment with humans
assumes paramount significance, and reinforcement learning with human feedback
(RLHF) emerges as the pivotal technological paradigm underpinning this pursuit.
Current technical routes usually include \textbf{reward models} to measure
human preferences, \textbf{Proximal Policy Optimization} (PPO) to optimize
policy model outputs, and \textbf{process supervision} to improve step-by-step
reasoning capabilities. However, due to the challenges of reward design,
environment interaction, and agent training, coupled with huge trial and error
cost of large language models, there is a significant barrier for AI
researchers to motivate the development of technical alignment and safe landing
of LLMs. The stable training of RLHF has still been a puzzle. In the first
report, we dissect the framework of RLHF, re-evaluate the inner workings of
PPO, and explore how the parts comprising PPO algorithms impact policy agent
training. We identify policy constraints being the key factor for the effective
implementation of the PPO algorithm. Therefore, we explore the PPO-max, an
advanced version of PPO algorithm, to efficiently improve the training
stability of the policy model. Based on our main results, we perform a
comprehensive analysis of RLHF abilities compared with SFT models and ChatGPT.
The absence of open-source implementations has posed significant challenges to
the investigation of LLMs alignment. Therefore, we are eager to release
technical reports, reward models and PPO code
Superconducting properties of molybdenum ruthenium alloy Mo
Resistance, magnetization and specific heat measurements were performed on Mo0.63Ru0.37 alloy. All of them confirm that Mo0.63Ru0.37 becomes superconducting at about 7.0 K with bulk nature. Its upper critical field behavior fits to Werthamer-Helfand-Hohenberg (WHH) model quite well, with an upper critical field of μ0Hc2(0) = 8.64 T, less than its Pauli limit. Its electronic specific heat is reproduced by Bardeen-Cooper-Schriffer (BCS)-based α-model with a gap ratio Δ0 = 1.88kBTc, which is a little larger than the standard BCS value of 1.76. We concluded that Mo0.63Ru0.37 is a fully gapped isotropic s-wave superconductor, with its features are mostly consistent with the conventional theory
Protective effects and plausible mechanisms of velvet polypeptide against hydrogen peroxide induced injury in human umbilical vein endothelial cells
Velvet antler polypeptide (VAP) is a prominent bioactive component of velvet antlers. Whereas, uncharacterized crude extracts were usually employed in pharmacological studies. In this study, the velvet polypeptide was isolated and purified by acid water extraction, ethanol precipitation, and ammonium sulfate fractionation and precipitation, and chromatography progressively. Human umbilical vein endothelial cells (HUVECs) were induced by H2O2 followed purified polypeptide treatment. Cell viability was evaluated by MTT assay. The apoptosis of cells was detected by fluorescence microscopy and flow cytometry. A cell analyzer was used to measure the mitochondrial membrane potential. The intracellular reactive oxygen species (ROS) levels were determined by flow cytometry. The oxidative stress related biochemical parameters were detected, and the expression of apoptosis related proteins was examined by Western blot analysis. Results indicated that a 7.0 kDa polypeptide (VAP II) was isolated from velvet antler. VAP II could enhance cell viability, decrease the cell apoptosis, reverse depolarization of mitochondrial membrane potential, decrease ROS, inhibit oxidative stress, and regulate downstream signaling apoptotic cascade expression caused by H2O2. The protective effects of VAP II on HUVEC injury provided a potential strategy for cardiovascular disease treatment.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
Electrical manipulation of skyrmions in a chiral magnet
There has been much interest in using skyrmions for new approaches to compution, however, creating, deleting and driving skyrmions remains a challenge. Here, Wang et al demonstrate all three operations for skyrmions in tailored Co8Zn10Mn2 nanodevices using tailored current pulses. Writing, erasing and computing are three fundamental operations required by any working electronic device. Magnetic skyrmions could be essential bits in promising in emerging topological spintronic devices. In particular, skyrmions in chiral magnets have outstanding properties like compact texture, uniform size, and high mobility. However, creating, deleting, and driving isolated skyrmions, as prototypes of aforementioned basic operations, have been a grand challenge in chiral magnets ever since the discovery of skyrmions, and achieving all these three operations in a single device is even more challenging. Here, by engineering chiral magnet Co8Zn10Mn2 into the customized micro-devices for in-situ Lorentz transmission electron microscopy observations, we implement these three operations of skyrmions using nanosecond current pulses with a low current density of about 10(10) A center dot m(-)(2) at room temperature. A notched structure can create or delete magnetic skyrmions depending on the direction and magnitude of current pulses. We further show that the magnetic skyrmions can be deterministically shifted step-by-step by current pulses, allowing the establishment of the universal current-velocity relationship. These experimental results have immediate significance towards the skyrmion-based memory or logic devices
Current-Controlled Topological Magnetic Transformations in a Nanostructured Kagome Magnet
Topological magnetic charge Q is a fundamental parameter that describes the
magnetic domains and determines their intriguing electromagnetic properties.
The ability to switch Q in a controlled way by electrical methods allows for
flexible manipulation of electromagnetic behavior in future spintronic devices.
Here we report the room-temperature current-controlled topological magnetic
transformations between Q = -1 skyrmions and Q = 0 stripes or type-II bubbles
in a kagome crystal FeSn. We show that the reproducible and reversible
skyrmion-bubble and skyrmion-stripe transformations can be achieved by tuning
the density of nanosecond pulsed current of the order of ~10 A.
Further numerical simulations suggest that spin-transfer torque combined with
Joule thermal heating effects determine the current-induced topological
magnetic transformations
The PIT1 gene polymorphisms were associated with chicken growth traits
BACKGROUND: With crucial roles on the differentiation of anterior pituitary and the regulation of the prolactin (PRL), growth hormone (GH) and thyroid-stimulating hormone-β (TSH-β) genes, the chicken PIT1 gene is regarded as a key candidate gene for production traits. In this study, five reported polymorphisms (MR1-MR5) of the PIT1 gene were genotyped in a full sib F(2 )resource population to evaluate their effects on growth, carcass and fatty traits in chickens. RESULTS: Marker-trait association analyses showed that, MR1 was significantly associated with shank diameters (SD) at 84 days (P < 0.05), hatch weight (HW) and shank length (SL) at 84 days (P < 0.01), MR2 was significantly associated with BW at 28, 42 days and average daily gain (ADG) at 0–4 weeks (P < 0.05), and MR3 was significantly associated with ADG at 4–8 weeks (P < 0.05). MR4 was associated with SL at 63, 77, 84 days and BW at 84 days (P < 0.05), as well as SD at 77 days (P < 0.01). Significant association was also found of MR5 with BW at 21, 35 days and SD at 63 days (P < 0.05), BW at 28 days and ADG at 0–4 weeks (P < 0.01). Both T allele of MR4 and C allele of MR5 were advantageous for chicken growth. The PIT1 haplotypes were significantly associated with HW (P = 0.0252), BW at 28 days (P = 0.0390) and SD at 56 days (P = 0.0400). No significant association of single SNP and haplotypes with chicken carcass and fatty traits was found (P > 0.05). CONCLUSION: Our study found that polymorphisms of PIT1 gene and their haplotypes were associated with chicken growth traits and not with carcass and fatty traits