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1.
J Ethnopharmacol ; 334: 118532, 2024 Jul 06.
Article in English | MEDLINE | ID: mdl-38972527

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: Astragaloside IV (AS), a key active ingredient obtained from Chinese herb Astragalus mongholicus Bunge, exerts potent neuroprotective and anti-inflammatory effects for treating neurodegenerative diseases. However, mechanisms of AS on improvement of ischemic brain tissue repair remain unclear. AIM OF THE STUDY: This research aims at using magnetic resonance imaging (MRI) to noninvasively determine whether AS facilitates brain tissue repair, and investigating whether AS exerts brain remodeling through adenosine monophosphate-activated protein kinase (AMPK) metabolic signaling regulating key glycolytic enzymes and energy transporters, thereby impacting microglia polarization. MATERIALS AND METHODS: Ischemic stroke model in male Sprague-Dawley rats were induced through permanent occlusion of the middle cerebral artery (MCAO). Infarct volume, the alterations of brain microstructure and nerve fibers reorganization were examined by multi-parametric MRI. The pathological damages of myelinated axons and microglia polarization surrounding infarct tissue were detected using pathological techniques. Furthermore, M1/M2 microglia polarization associated protein, glycolytic rate-limiting enzymes, energy transporters and AMPK/mammalian target of rapamycin (mTOR)/hypoxia inducible factor-1α (HIF-1α) signal were examined both in ischemic stroke rats and BV2 microglia treated with lipopolysaccharide (LPS) + interferon-γ (IFN-γ) by western blotting. RESULTS: MRI revealed that AS obviously decreased infarct volume, relieved brain microstructure damage and improved nerve fibers reorganization in ischemic stroke rats. Histological tests supported MRI findings. Notably, AS promoted microglia M2 and reduced M1 polarization, induced the AMPK activation accompanied with decreased levels of phosphorylated mTOR and HIF-1α. Moreover, AS suppressed the expression of glycolytic rate-limiting enzymes and energy transporters in ischemic stroke rats and BV2 microglia. In contrast, these beneficial effects were greatly blocked by AMPK inhibitor compound C. CONCLUSION: Overall, these results collectively suggested that AS facilitated tissue remodeling that may be partially through modulating polarization of microglia in AMPK- dependent metabolic pathways after ischemic stroke.

2.
Nature ; 2024 Jul 10.
Article in English | MEDLINE | ID: mdl-38987606

ABSTRACT

The fermionic Hubbard model (FHM)1 describes a wide range of physical phenomena resulting from strong electron-electron correlations, including conjectured mechanisms for unconventional superconductivity. Resolving its low-temperature physics is, however, challenging theoretically or numerically. Ultracold fermions in optical lattices2,3 provide a clean and well-controlled platform offering a path to simulate the FHM. Doping the antiferromagnetic ground state of a FHM simulator at half-filling is expected to yield various exotic phases, including stripe order4, pseudogap5, and d-wave superfluid6, offering valuable insights into high-temperature superconductivity7-9. Although the observation of antiferromagnetic correlations over short10 and extended distances11 has been obtained, the antiferromagnetic phase has yet to be realized as it requires sufficiently low temperatures in a large and uniform quantum simulator. Here we report the observation of the antiferromagnetic phase transition in a three-dimensional fermionic Hubbard system comprising lithium-6 atoms in a uniform optical lattice with approximately 800,000 sites. When the interaction strength, temperature and doping concentration are finely tuned to approach their respective critical values, a sharp increase in the spin structure factor is observed. These observations can be well described by a power-law divergence, with a critical exponent of 1.396 from the Heisenberg universality class12. At half-filling and with optimal interaction strength, the measured spin structure factor reaches 123(8), signifying the establishment of an antiferromagnetic phase. Our results provide opportunities for exploring the low-temperature phase diagram of the FHM.

3.
Vet Sci ; 11(5)2024 May 07.
Article in English | MEDLINE | ID: mdl-38787175

ABSTRACT

Several trichomonad species have already been identified in pigs, and their pathogenic potential may not be ruled out. To date, however, no information is available regarding the prevalence of trichomonads in pigs in Shanxi Province, North China. In the present study, a total of 362 fecal samples collected from pigs in three representative counties (Qi, Jishan, and Shanyin) in this province were examined for Tetratrichomonas buttreyi, Tritrichomonas foetus, and Pentatrichomonas hominis using a nested polymerase chain reaction (PCR) with primers targeting the small subunit ribosomal RNA (SSU rRNA) gene. The overall prevalence of T. buttreyi was 49.72%, and region and age were found to be significantly associated with T. buttreyi infection, respectively. Only one pig fecal sample from Qi County was found to be positive for T. foetus, and all samples were negative for P. hominis. Molecular evolutionary analysis revealed that some T. buttreyi isolates showed complete genetic identity with those reported previously, and some T. buttreyi isolates and one T. foetus isolate showed minor allelic variations compared with those reported previously. This is the report of the molecular epidemiology of T. foetus and T. buttreyi in pigs in Shanxi Province, North China. These findings not only enrich the knowledge on the distribution of these trichomonad species in pigs in China but also provide baseline information for planning future research and control strategies.

4.
Nat Prod Res ; : 1-10, 2024 Apr 02.
Article in English | MEDLINE | ID: mdl-38563116

ABSTRACT

Phytochemical investigation of the roots of Saposhnikovia divaricata (Turcz.) Schischk resulted in the isolation of twelve coumarin derivatives including one new 3,4-dihydroisocoumarin (1) and eleven known 3,4-unsubstituted coumarins (2-12). Structural elucidation of compounds 1-12 was established by 1D and 2D NMR spectra referring to the literature, together with high-resolution mass spectrometric analysis. LPS-induced RAW264.7 inflammatory cell model was used to determine the potential antiinflammation activity of all the isolated compounds in vitro. The results showed that compound 3 significantly inhibited the production of lipopolysaccharide (LPS)-induced NO in macrophages (IC50 = 4.54 ± 1.71 µM), more active than the positive control (L-NMMA).

5.
Fitoterapia ; 174: 105876, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38431027

ABSTRACT

Nine polyacetylenes, including five new compounds named sadivaethynes E-I (1-5), were isolated from the roots of Saposhnikovia divaricata. Structural elucidation of compounds 1-5 was established by extensive spectroscopic analysis, quantum chemical calculations and DP4+ probability analysis. Among them, the absolute configuration of compound 1-2, 4-5 was unambiguous determined by ECD. Also, all compounds were evaluated for cytotoxicity against two human cancer cell lines (A549, HEPG2) in vitro, compound 9 showed moderate inhibitory effect with an IC50 value of 11.66 µM against HEPG2.


Subject(s)
Apiaceae , Polyynes , Humans , Molecular Structure , Polyynes/pharmacology , Polyynes/analysis , Polyynes/chemistry , Plant Roots/chemistry , Plant Extracts/chemistry , Apiaceae/chemistry
6.
Materials (Basel) ; 17(5)2024 Feb 24.
Article in English | MEDLINE | ID: mdl-38473518

ABSTRACT

The aminated sodium lignosulfonate (AELS) was prepared through a Mannich reaction and characterized via FT-IR, TG, SEM and XPS in this study. Subsequently, the adsorption capacity of AELS for methyl blue (MB) was evaluated under various conditions such as pH, adsorbent dosage, contact time, initial concentration and temperature. The adsorption kinetics, isotherms and thermodynamics of AELS for methyl blue were investigated and analyzed. The results were found to closely adhere to the pseudo-second-order kinetic model and Langmuir isotherm model, suggesting a single-molecular-layer adsorption process. Notably, the maximum adsorption capacity of AELS for methyl blue (153.42 mg g-1) was achieved under the specified conditions (T = 298 K, MAELS = 0.01 g, pH = 6, VMB = 25 mL, C0 = 300 mg L-1). The adsorption process was determined to be spontaneous and endothermic. Following five adsorption cycles, the adsorption capacity exhibited a minimal reduction from 118.99 mg g-1 to 114.33 mg g-1, indicating good stability. This study contributes to the advancement of utilizing natural resources effectively and sustainably.

7.
Anal Chem ; 96(12): 4835-4844, 2024 Mar 26.
Article in English | MEDLINE | ID: mdl-38488022

ABSTRACT

The rapid proliferation of new psychoactive substances (NPS) poses significant challenges to conventional mass-spectrometry-based identification methods due to the absence of reference spectra for these emerging substances. This paper introduces PS2MS, an AI-powered predictive system designed specifically to address the limitations of identifying the emergence of unidentified novel illicit drugs. PS2MS builds a synthetic NPS database by enumerating feasible derivatives of known substances and uses deep learning to generate mass spectra and chemical fingerprints. When the mass spectrum of an analyte does not match any known reference, PS2MS simultaneously examines the chemical fingerprint and mass spectrum against the putative NPS database using integrated metrics to deduce possible identities. Experimental results affirm the effectiveness of PS2MS in identifying cathinone derivatives within real evidence specimens, signifying its potential for practical use in identifying emerging drugs of abuse for researchers and forensic experts.


Subject(s)
Deep Learning , Illicit Drugs , Chromatography, Liquid/methods , Psychotropic Drugs/analysis , Mass Spectrometry/methods , Illicit Drugs/analysis , Substance Abuse Detection/methods
8.
Cell Res ; 34(4): 281-294, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38200278

ABSTRACT

Plant survival requires an ability to adapt to differing concentrations of nutrient and toxic soil ions, yet ion sensors and associated signaling pathways are mostly unknown. Aluminum (Al) ions are highly phytotoxic, and cause severe crop yield loss and forest decline on acidic soils which represent ∼30% of land areas worldwide. Here we found an Arabidopsis mutant hypersensitive to Al. The gene encoding a leucine-rich-repeat receptor-like kinase, was named Al Resistance1 (ALR1). Al ions binding to ALR1 cytoplasmic domain recruits BAK1 co-receptor kinase and promotes ALR1-dependent phosphorylation of the NADPH oxidase RbohD, thereby enhancing reactive oxygen species (ROS) generation. ROS in turn oxidatively modify the RAE1 F-box protein to inhibit RAE1-dependent proteolysis of the central regulator STOP1, thus activating organic acid anion secretion to detoxify Al. These findings establish ALR1 as an Al ion receptor that confers resistance through an integrated Al-triggered signaling pathway, providing novel insights into ion-sensing mechanisms in living organisms, and enabling future molecular breeding of acid-soil-tolerant crops and trees, with huge potential for enhancing both global food security and forest restoration.


Subject(s)
Arabidopsis Proteins , Arabidopsis , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Aluminum/metabolism , Reactive Oxygen Species/metabolism , Arabidopsis/genetics , Arabidopsis/metabolism , Ions , Soil , Gene Expression Regulation, Plant , Transcription Factors/metabolism
9.
Bioresour Technol ; 393: 130140, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38043687

ABSTRACT

The adsorption behaviors of biochar are largely impacted by biomassfeedstock. In this study, two biochars were prepared from torrefaction of ammonium persulfate- and potassium persulfate-pretreated bamboo and then activated by cold alkali, which are named as ASBC and KSBC, respectively. The two biochars were characterized by different instruments, and their adsorption properties over cationic methylene blue (MB) were compared. The type of persulfates little affected the specific surface areas, but significantly impacted O (29.54 % vs. 35.113 %) and N (12.13 % vs. 3.74 %) contents, functional groups, and zeta potentials of biochars. MB adsorption onto ASBC/KSBC is a single-layer chemical endothermic process and ASBC/KSBC exhibit high adsorption capacity over MB (475/881 mg·g-1) at 303 K. Obviously, the sorption capacity of MB onto KSBC much surpasses that of MB onto ASBC. These results indicate biomass pre-treatment is a cheap and convenient method to prepare biochars with unique physicochemical and adsorptive properties.


Subject(s)
Charcoal , Water Pollutants, Chemical , Adsorption , Charcoal/chemistry , Alkalies , Methylene Blue/chemistry , Water Pollutants, Chemical/chemistry
10.
Curr Biol ; 34(2): 313-326.e7, 2024 01 22.
Article in English | MEDLINE | ID: mdl-38101405

ABSTRACT

Root hairs are tubular-shaped outgrowths of epidermal cells essential for plants acquiring water and nutrients from the soil. Despite their importance, the growth of root hairs is finite. How this determinate growth is precisely regulated remains largely unknown. Here we identify LONG ROOT HAIR (LRH), a GYF domain-containing protein, as a unique repressor of root hair growth. We show that LRH inhibits the association of eukaryotic translation initiation factor 4Es (eIF4Es) with the mRNA of ROOT HAIR DEFECTIVE6-LIKE4 (RSL4) that encodes the master regulator of root hair growth, repressing RSL4 translation and thus root hair elongation. RSL4 in turn directly transactivates LRH expression to maintain a proper LRH gradient in the trichoblasts. Our findings reveal a previously uncharacterized LRH-RSL4 feedback regulatory loop that limits root hair growth, shedding new light on the mechanism underlying the determinate growth of root hairs.


Subject(s)
Arabidopsis Proteins , Arabidopsis , Arabidopsis/genetics , Arabidopsis Proteins/metabolism , Feedback , Plant Roots , Cell Proliferation , Gene Expression Regulation, Plant , Basic Helix-Loop-Helix Transcription Factors/metabolism
11.
Nanomaterials (Basel) ; 13(24)2023 Dec 15.
Article in English | MEDLINE | ID: mdl-38133048

ABSTRACT

Cellulose-based carbon (CBC) is widely known for its porous structure and high specific surface area and is liable to adsorb gas molecules and macromolecular pollutants. However, the application of CBC in gas sensing has been little studied. In this paper, a ZnO/CBC heterojunction was formed by means of simple co-precipitation and high-temperature carbonization. As a new ammonia sensor, the prepared ZnO/CBC sensor can detect ammonia that the previous pure ZnO ammonia sensor cannot at room temperature. It has a great gas sensing response, stability, and selectivity to an ammonia concentration of 200 ppm. This study provides a new idea for the design and synthesis of biomass carbon-metal oxide composites.

12.
J Fungi (Basel) ; 9(11)2023 Nov 10.
Article in English | MEDLINE | ID: mdl-37998901

ABSTRACT

Endophytic fungi isolated from medicinal ferns serve as significant natural resources for drug precursors or bioactive metabolites. During our survey on the diversity of endophytic fungi from Dicranopteris species (a genus of medicinal ferns) in Guizhou, Apoiospora was observed as a dominant fungal group. In this study, seven Apiospora strains, representing four new species, were obtained from the healthy plant tissues of three Dicranopteris species-D. ampla, D. linearis, and D. pedata. The four new species, namely Apiospora aseptata, A. dematiacea, A. dicranopteridis, and A. globosa, were described in detail with color photographs and subjected to phylogenetic analyses using combined LSU, ITS, TEF1-α, and TUB2 sequence data. This study also documented three new hosts for Apiospora species.

13.
J Orthop Surg Res ; 18(1): 817, 2023 Oct 31.
Article in English | MEDLINE | ID: mdl-37907921

ABSTRACT

PURPOSE: Temporomandibular joint osteoarthritis (TMJOA) is a common disease that negatively affects the life quality of human beings. Circadian rhythm acts an important role in life activities. However, whether the clock genes are rhythmic expressed in mandibular condylar chondrocytes, or the clock genes have an effect on the progression of TMJOA remains unknown. In this study, we aim to explore expression of clock genes and regulatory mechanism of TMJOA in rat mandibular condylar chondrocytes. METHODS: After synchronized by dexamethasone, the expression of core clock genes Per1, Per2, Clock, Cry1, Cry2 and Bmal1 and cartilage matrix degrading factor gene Mmp13 were analyzed in mandibular condylar chondrocytes every 4 h with RT-qPCR. The mandibular condylar chondrocytes were stimulated with IL-1ß, and expression of Per1, Mmp13, P65 and p-P65 was assessed by RT-qPCR and Western blot. Sh-Per1 lentivirus was used to assess the effect of clock gene Per1 in IL-1ß-induced chondrocytes, and expression of Mmp13, P65 and p-P65 was measured. After establishing a rat TMJOA model using unilateral anterior crossbite (UAC), micro-CT, H & E, Alcian Blue & Nuclear Fast Red and Safranin O & Fast Green, cartilage thickness was utilized to assess the damage of cartilage and subchondral bone. Immunohistochemistry of PER1, MMP13 and P65 was performed in condylar sections. RESULTS: All core clock genes and Mmp13 were rhythmically expressed. And Mmp13 expression curve was closed in phase and amplitude with Per1. After stimulation with IL-1ß, the expression of MMP13, PER1 and P65 and ratio of p-P65/P65 increased in condylar chondrocytes. After Per1 was down-regulated in condylar chondrocytes, the expression of MMP13 and P65 and ratio of p-P65/P65 decreased. Compared with the condyles of Sham group, the bony parameters of UAC group were significantly worse. The thickness of cartilage in UAC group significantly reduced. The modified Mankin scores and the expression of PER1, MMP13 and P65 in cartilage of UAC group significantly increased compared with Sham group. CONCLUSION: Core clock genes and Mmp13 are rhythmic expressed in rat mandibular condylar chondrocytes. PER1 can regulate the expression of MMP13 through NF-κB pathway in IL-1ß-induced mandibular condylar chondrocytes.


Subject(s)
NF-kappa B , Osteoarthritis , Animals , Rats , Chondrocytes/metabolism , Mandibular Condyle/metabolism , Matrix Metalloproteinase 13/genetics , Matrix Metalloproteinase 13/metabolism , NF-kappa B/metabolism , Osteoarthritis/genetics , Osteoarthritis/metabolism , Period Circadian Proteins/genetics , Period Circadian Proteins/metabolism , Temporomandibular Joint/metabolism
14.
World J Pediatr ; 19(10): 972-982, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37029331

ABSTRACT

BACKGROUND: Previous studies have linked gestational diabetes (GDM) with allergies in offspring. However, the effect of specific glucose metabolism metrics was not well characterized, and the role of polyunsaturated fatty acids (PUFAs), a modifier of metabolism and the immune system, was understudied. We aimed to investigate the association between maternal GDM and allergic diseases in children and the interaction between glucose metabolism and PUFAs on allergic outcomes. METHODS: This prospective cohort study included 706 mother-child dyads from Guangzhou, China. Maternal GDM was diagnosed via a 75-g oral glucose tolerance test (OGTT), and dietary PUFAs were assessed using a validated food frequency questionnaire. Allergic disease diagnoses and the age of onset were obtained from medical records of children within three years old. RESULTS: Approximately 19.4% of women had GDM, and 51.3% of children had any allergic diseases. GDM was positively associated with any allergic diseases (hazard ratio [HR] 1.40; 95% confidence interval (CI) 1.05-1.88) and eczema (HR 1.44; 95% CI 1.02-1.97). A unit increase in OGTT after two hours (OGTT-2 h) glucose was associated with an 11% (95% CI 2%-21%) higher risk of any allergic diseases and a 17% (95% CI 1-36%) higher risk of food allergy. The positive associations between OGTT-2 h glucose and any allergic diseases were strengthened with decreased dietary a-linolenic acid (ALA) and increased n-6 PUFAs, linoleic acid (LA), LA/ALA ratio, and n-6/n-3 PUFA ratio. CONCLUSIONS: Maternal GDM was adversely associated with early-life allergic diseases, especially eczema. We were the first to identify OGTT-2 h glucose to be more sensitive in inducing allergy risk and that dietary PUFAs might modify the associations.


Subject(s)
Diabetes, Gestational , Eczema , Hypersensitivity , Pregnancy , Female , Humans , Child, Preschool , Diabetes, Gestational/diagnosis , Diabetes, Gestational/epidemiology , Cohort Studies , Prospective Studies , Hypersensitivity/epidemiology , Glucose
15.
Ying Yong Sheng Tai Xue Bao ; 34(3): 751-760, 2023 Mar.
Article in English | MEDLINE | ID: mdl-37087659

ABSTRACT

Ecological compensation plays an important role in maintaining ecosystem services and promoting regional green development. We built a regional horizontal ecological compensation model based on water resources pattern and insurance gain, and which was used to solve the problems of single compensation method and low compensation efficiency. Taking the Beijing-Tianjin-Hebei region as an example, we analyzed water footprint and water ecological carrying capacity from 2000 to 2019. The compensation subject and object and water footprint compensation amount were determined according to the input cost of ecological protection and allocation factor. Then, the insurance pricing model was introduced to determine ecological insurance premium rate. We calculated insurance compensation, ecological compensation standard and different types of ecosystem service value. Results showed that the whole region was at a state of water ecological deficit, with the agricultural water footprint accounting for 94.5%. From the perspective of the compensation subject and object, Beijing and Tianjin, as the compensation subject, needed to pay 0.402 billion yuan and 0.396 billion yuan (the amount of compensation) to Hebei Province each year. Hebei Province obtained a total of 0.228 billion yuan of ecological insurance with an insurance premium rate of 1.4%, and should receive an average annual ecological compensation standard of 0.81 billion yuan from Beijing and Tianjin. Hydrological regulation was the core ecosystem service in the region, with an average value of 187.974 billion yuan. It was of strategic significance to introduce ecological insurance mechanism to construct horizontal ecological compensation mechanism, improve ecosystem service function, and enhance the value of ecosystem services in the study area.


Subject(s)
Ecosystem , Water Resources , Conservation of Natural Resources , Beijing , Water , China
16.
Bioresour Technol ; 379: 129067, 2023 Jul.
Article in English | MEDLINE | ID: mdl-37080438

ABSTRACT

Hydrochars are promising sorbents for wastewater treatment. Herein, two acrylate-modified hydrochars (AMHC1 and AMHC2) were obtained by grafting acrylic acid on the surface of two hydrochars (MHC1 and MHC2 hydrothermally carbonized in water and acidic medium respectively) with free radical polymerization. Characterizations show that MHC2 is more prone to free radical polymerization than MHC1 does, and has higher carboxylate content after modification. The adsorption amounts of AMHC2 over methylene blue (MB) and Pb(II) are much higher than those of AMHC1. Pseudo-second-order kinetic and Langmuir isotherm equations well fit the Pb(II) and MB sorption data of AMHC2. The Pb(II) adsorptive mechanism is mainly inner-surface complexation accompanied by ion exchange and cation-π interaction. MB adsorption involves ion exchange, electrostatic interaction, H-bonding and π-π interaction. Hence, the one-step modification method of free radical polymerization under alkaline condition has great potential for preparing carboxylate-modified hydrochars to adsorb cationic pollutants.


Subject(s)
Methylene Blue , Water Pollutants, Chemical , Methylene Blue/analysis , Lead , Adsorption , Water Pollutants, Chemical/analysis , Acrylates , Water , Kinetics , Carboxylic Acids , Hydrogen-Ion Concentration
17.
Bioorg Chem ; 134: 106447, 2023 05.
Article in English | MEDLINE | ID: mdl-36889198

ABSTRACT

Fifteen new chromones, sadivamones A-E (1-5), cimifugin monoacetate (6), sadivamones F-N (7-15), together with fifteen known chromones (16-30), were isolated from the ethyl acetate portions of 70% ethanol extract of Saposhnikovia divaricata (Turcz.) Schischk roots. The structures of the isolates were determined using 1D/2D NMR data and electron circular dichroism (ECD) calculations. Meanwhile, LPS induced RAW264.7 inflammatory cell model was used to determine the potential anti-inflammatory activity of all the isolated compounds in vitro. The results showed that compounds 2, 8, 12-13, 18, 20-22, 24, and 27 significantly inhibited the production of lipopolysaccharide (LPS)-induced NO in macrophages. To determine the signaling pathways involved in the suppression of NO production by compounds 8, 12 and 13, we investigated ERK and c-Jun N-terminal protein kinase (JNK) expression by western blot analysis. Further mechanistic studies demonstrated that compounds 12 and 13 inhibited the phosphorylation of ERK and the activation of ERK and JNK signaling in RAW264.7 cells via MAPK signaling pathways. Taken together, compounds 12 and 13 may be valuable candidates for the treatment of inflammatory diseases.


Subject(s)
Apiaceae , Drugs, Chinese Herbal , Lipopolysaccharides/pharmacology , Drugs, Chinese Herbal/pharmacology , Apiaceae/chemistry , Chromones/pharmacology , Chromones/chemistry , Anti-Inflammatory Agents/pharmacology
18.
Nat Mater ; 22(5): 583-590, 2023 May.
Article in English | MEDLINE | ID: mdl-36894774

ABSTRACT

Using circularly polarized light to control quantum matter is a highly intriguing topic in physics, chemistry and biology. Previous studies have demonstrated helicity-dependent optical control of chirality and magnetization, with important implications in asymmetric synthesis in chemistry; homochirality in biomolecules; and ferromagnetic spintronics. We report the surprising observation of helicity-dependent optical control of fully compensated antiferromagnetic order in two-dimensional even-layered MnBi2Te4, a topological axion insulator with neither chirality nor magnetization. To understand this control, we study an antiferromagnetic circular dichroism, which appears only in reflection but is absent in transmission. We show that the optical control and circular dichroism both arise from the optical axion electrodynamics. Our axion induction provides the possibility to optically control a family of [Formula: see text]-symmetric antiferromagnets ([Formula: see text], inversion; [Formula: see text], time-reversal) such as Cr2O3, even-layered CrI3 and possibly the pseudo-gap state in cuprates. In MnBi2Te4, this further opens the door for optical writing of a dissipationless circuit formed by topological edge states.

19.
Natl Sci Rev ; 9(10): nwab226, 2022 Oct.
Article in English | MEDLINE | ID: mdl-36380857

ABSTRACT

Atomic Fermi gases provide an ideal platform for studying pairing and superfluid physics, using a Feshbach resonance between closed-channel molecular states and open-channel scattering states. Of particular interest is the strongly interacting regime. We show that the closed-channel fraction [Formula: see text] provides an effective probe for important many-body interacting effects, especially through its density dependence, which is absent from two-body theoretical predictions. Here we measure [Formula: see text] as a function of interaction strength and the Fermi temperature [Formula: see text] in a trapped 6Li superfluid throughout the entire Bardeen-Cooper-Schrieffer-Bose-Einstein-condensate crossover, in quantitative agreement with theory when important thermal contributions outside the superfluid core are taken into account. Away from the deep-BEC regime, the fraction [Formula: see text] is sensitive to [Formula: see text]. In particular, our data show [Formula: see text] with [Formula: see text] at unitarity, in quantitative agreement with calculations of a two-channel pairing fluctuation theory, and [Formula: see text] increases rapidly into the BCS regime, reflecting many-body interaction effects as predicted.

20.
Phys Rev Lett ; 129(16): 163602, 2022 Oct 14.
Article in English | MEDLINE | ID: mdl-36306767

ABSTRACT

We systematically study the decay of quasi-two-dimensional vortices in an oblate strongly interacting Fermi gas over a wide interaction range and observe that, as the system temperature is lowered, the vortex lifetime increases in the Bose-Einstein condensate (BEC) regime but decreases at unitarity and in the Bardeen-Cooper-Schrieffer (BCS) regime. The observations can be qualitatively captured by a phenomenological model simply involving diffusion and two-body collisional loss, in which the vortex lifetime is mostly determined by the slower process of the two. In particular, the counterintuitive vortex decay in the BCS regime can be interpreted by considering the competition between the temperature dependence of the vortex annihilation rate and that of unpaired fermions. Our results suggest a competing mechanism for the complex vortex decay dynamics in the BCS-BEC crossover for the fermionic superfluids.

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