Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 70
Filter
1.
Adv Sci (Weinh) ; : e2403513, 2024 Jul 17.
Article in English | MEDLINE | ID: mdl-39018207

ABSTRACT

Uncontrollable growth of Zn dendrites, irreversible dissolution of cathode material and solidification of aqueous electrolyte at low temperatures severely restrict the development of aqueous Zn-ion batteries. In this work, 2,2,2-trifluoroethanol (TFEA) with a volume fraction of 50% as a highly compatible polar-solvent is introduced to 1.3 M Zn(CF3SO3)2 aqueous electrolyte, achieving stable high-performance Zn-ion batteries. Massive theoretical calculations and characterization analysis demonstrate that TFEA weakens the tip effect of Zn anode and restrains the growth of Zn dendrites due to electrostatic adsorption and coordinate with H2O to disrupt the hydrogen bonding network in water. Furthermore, TFEA increases the wettability of the cathode and alleviates the dissolution of V2O5, thus improving the capacity of the full battery. Based on those positive effects of TFEA on Zn anode, V2O5 cathode, and aqueous electrolyte, the Zn//Zn symmetric cell delivers a long cycle-life of 782 h at 5 mA cm-2 and 2 mA h cm-2. The full battery still declares an initial capacity of 116.78 mA h g-1, and persists 87.73% capacity in 2000 cycles at -25 °C. This work presents an effective strategy for fully compatible co-solvent to promote the stability of Zn anode, V2O5 cathode and aqueous electrolyte for high-performance Zn-ion batteries.

2.
Adv Sci (Weinh) ; : e2403852, 2024 Jul 10.
Article in English | MEDLINE | ID: mdl-38984469

ABSTRACT

Chiral spin textures, as exotic phases in magnetic materials, hold immense promise for revolutionizing logic, and memory applications. Recently, chiral spin textures have been observed in centrosymmetric magnetic insulators (FMI), due to an interfacial Dzyaloshinskii-Moriya interaction (iDMI). However, the source and origin of this iDMI remain enigmatic in magnetic insulator systems. Here, the source and origin of the iDMI in Pt/Y3Fe5O12 (YIG)/substrate structures are deeply delved by examining the spin-Hall topological Hall effect (SH-THE), an indication of chiral spin textures formed due to an iDMI. Through carefully modifying the interfacial chemical composition of Pt/YIG/substrate with a nonmagnetic Al3+ doping, the obvious dependence of SH-THE on the interfacial chemical composition for both the heavy metal (HM)/FMI and FMI/substrate interfaces is observed. The results reveal that both interfaces contribute to the strength of the iDMI, and the iDMI arises due to strong spin-orbit coupling and inversion symmetry breaking at both interfaces in HM/FMI/substrate. Importantly, it is shown that nonmagnetic substitution and interface engineering can significantly tune the SH-THE and iDMI in ferrimagnetic iron garnets. The approach offers a viable route to tailor the iDMI and associated chiral spin textures in low-damping insulating magnetic oxides, thus advancing the field of spintronics.

3.
Nano Lett ; 24(22): 6714-6721, 2024 Jun 05.
Article in English | MEDLINE | ID: mdl-38781452

ABSTRACT

The cycle stability of lithium metal anode (LMA) largely depends on solid-electrolyte interphase (SEI). Electrolyte engineering is a common strategy to adjust SEI properties, yet understanding its impact is challenging due to limited knowledge on ultrafine SEI structures. Herein, using cryogenic transmission electron microscopy, we reveal the atomic-level SEI structure of LMA in ether-based electrolytes, focusing on the role of LiNO3 additives in SEI modulation at different temperature (25 and 50 °C). Poor cycle stability of LMA in the baseline electrolyte without LiNO3 additives stems from the Li2CO3-rich mosaic-type SEI. Increased LiNO3 content and elevated operating temperature enhance cyclic performance by forming bilayer or multilayer SEI structures via preferential LiNO3 decomposition, but may thicken the SEI, leading to reduced initial Coulombic efficiency and increased overpotential. The optimal SEI features a multilayer structure with Li2O-rich inner layer and closely packed grains in the outer layer, minimizing electrolyte decomposition or corrosion.

4.
J Am Chem Soc ; 146(5): 2977-2985, 2024 Feb 07.
Article in English | MEDLINE | ID: mdl-38284994

ABSTRACT

The recently surged halide-based solid electrolytes (SEs) are great candidates for high-performance all-solid-state batteries (ASSBs), due to their decent ionic conductivity, wide electrochemical stability window, and good compatibility with high-voltage oxide cathodes. In contrast to the crystalline phases in halide SEs, amorphous components are rarely understood but play an important role in Li-ion conduction. Here, we reveal that the presence of amorphous component is common in halide-based SEs that are prepared via mechanochemical method. The fast Li-ion migration is found to be associated with the local chemistry of the amorphous proportion. Taking Zr-based halide SEs as an example, the amorphization process can be regulated by incorporating O, resulting in the formation of corner-sharing Zr-O/Cl polyhedrons. This structural configuration has been confirmed through X-ray absorption spectroscopy, pair distribution function analyses, and Reverse Monte Carlo modeling. The unique structure significantly reduces the energy barriers for Li-ion transport. As a result, an enhanced ionic conductivity of (1.35 ± 0.07) × 10-3 S cm-1 at 25 °C can be achieved for amorphous Li3ZrCl4O1.5. In addition to the improved ionic conductivity, amorphization of Zr-based halide SEs via incorporation of O leads to good mechanical deformability and promising electrochemical performance. These findings provide deep insights into the rational design of desirable halide SEs for high-performance ASSBs.

5.
J Am Chem Soc ; 145(50): 27500-27511, 2023 Dec 20.
Article in English | MEDLINE | ID: mdl-38056604

ABSTRACT

Anion-exchange membrane fuel cells (AEMFCs) are promising alternative hydrogen conversion devices. However, the sluggish kinetics of the hydrogen oxidation reaction in alkaline media hinders further development of AEMFCs. As a synthesis method commonly used to prepare disordered PtRu alloys, the impregnation process is ingeniously designed herein to synthesize sub-3 nm Pt@Ru core-shell nanoparticles by sequentially reducing Pt and Ru at different annealing temperatures. This method avoids complex procedures and synthesis conditions for organic synthesis systems, and the atomic structure evolution of the synthesized core-shell nanoparticles can be tracked. The synthesized Pt@Ru electrocatalyst shows an ultrasmall average size of ∼2.5 nm and thereby a large electrochemical surface area (ECSA) of 166.66 m2 gPt+Ru-1. Exchange current densities (j0) normalized to the mass (Pt + Ru) and ECSA of this electrocatalyst are 8.0 and 5.8 times as high as those of commercial Pt/C, respectively. To the best of our knowledge, the achieved mass-normalized j0 measured by rotating disk electrodes is the highest reported so far. The membrane electrode assembly test of the Pt@Ru electrocatalyst shows a peak power density of 1.78 W cm-2 (0.152 mgPt+Ru cmanode-2), which is higher than that of commercial PtRu/C (1.62 W cm-2, 0.211 mgPt+Ru cmanode-2). The improvement of the intrinsic activity can be attributed to the electron transfer from the Ru shell to the Pt core, and the ultrafine particles further enhance the mass activity. This work reveals the feasibility of using simple impregnation to synthesize fine core-shell nanocatalysts and the importance of investigating the atomic structure of PtRu nanoparticles and other disordered alloys.

6.
ACS Nano ; 17(21): 21730-21738, 2023 Nov 14.
Article in English | MEDLINE | ID: mdl-37903817

ABSTRACT

Emerging dual-graphite batteries (DGBs) capture extensive interest for their high output voltage and exceptional cost-effectiveness. Yet, developing electrolytes compatible with both the cathode and anode stands to be a tremendous challenge, and how electrolyte impacts anion and cation intercalation into graphite remains inexplicit or controversial. Herein, we have evaluated the performance of graphite anode and cathode in typical ethyl methyl carbonate (EMC) based electrolytes and unveiled their electrode-electrolyte interphase using Cryogenic transmission electron microscopy (Cryo-TEM). The addition of fluoroethylene carbonate (FEC) brings substantial improvement in cycle stability and Coulombic efficiency for both the graphite cathode and anode, but its implication on cation and anion intercalation differs. FEC is involved in anodic side reactions to produce a LiF-embedded solid-electrolyte interphase layer. It is much thinner and more uniform than that formed in the electrolyte without FEC, which is correlated with less graphite exfoliation and enhanced stability. As for the graphite cathode, both basal and edge planes are largely bare, and only few scattered byproducts are found. In addition, we also reveal layer bending and local lattice disordering of the graphite cathode based on multiple Cryo-TEM images, which are speculated to be caused by high lattice strain induced by anion intercalation and local oxidation under high voltage. The absence of cathode-electrolyte interphase (CEI) layers overturns the paradigm of attributing cathodic performance to CEI features and is regarded as a fundamental reason for severe self-discharge of graphite cathode. FEC helps to alleviate graphite exfoliation issues and enhance cycle stability, and we ascribe it to weakened solvation, which means reduced probability of solvent co-intercalation during charging, rather than compositional changes of cathodic byproducts.

7.
J Phys Chem Lett ; 14(42): 9441-9447, 2023 Oct 26.
Article in English | MEDLINE | ID: mdl-37827112

ABSTRACT

The advancement of science and technology is always accompanied by better manufacturing precision. Ideally, the highest precision for manufacturing a surface is truly atomic flatness, which implies that all topmost surface atoms are in a single layer of the crystal face. However, almost no methods can achieve this surface with high efficiency at present. Herein, we present a method to fabricate a large-scale truly atomically flat surface with ultrafast speed. Through the selective etching of surface atoms, our method can achieve an atomically flat surface with 0.05 nm Sa roughness. It is notable that the polishing efficiency of our method is more than 1000 times higher than that of conventional methods. We have demonstrated its generality on various single-crystal materials and obtained atomic roughness and an ultrahigh polishing rate. This method has the potential to promote the mass-production of atomic-scale smooth surfaces, the application of third-generation semiconductor materials, and the innovation of advanced technologies.

8.
Heliyon ; 9(5): e15877, 2023 May.
Article in English | MEDLINE | ID: mdl-37305464

ABSTRACT

[This corrects the article DOI: 10.1016/j.heliyon.2023.e15229.].

9.
Angew Chem Int Ed Engl ; 62(30): e202305723, 2023 Jul 24.
Article in English | MEDLINE | ID: mdl-37285084

ABSTRACT

A stable solid electrolyte interphase (SEI) layer is crucial for lithium metal anode (LMA) to survive in long-term cycling. However, chaotic structures and chemical inhomogeneity of natural SEI make LMA suffering from exasperating dendrite growth and severe electrode pulverization, which hinder the practical application of LMAs. Here, we design a catalyst-derived artificial SEI layer with an ordered polyamide-lithium hydroxide (PA-LiOH) bi-phase structure to modulate ion transport and enable dendrite-free Li deposition. The PA-LiOH layer can substantially suppress the volume changes of LMA during Li plating/stripping cycles, as well as alleviate the parasitic reactions between LMA and electrolyte. The optimized LMAs demonstrate excellent stability in Li plating/stripping cycles for over 1000 hours at an ultra-high current density of 20 mA cm-2 in Li||Li symmetric cells. A high coulombic efficiency up to 99.2 % in Li half cells in additive-free electrolytes is achieved even after 500 cycles at a current density of 1 mA cm-2 with a capacity of 1 mAh cm-2 .

10.
Light Sci Appl ; 12(1): 129, 2023 May 29.
Article in English | MEDLINE | ID: mdl-37248287

ABSTRACT

Raman and Brillouin scattering are sensitive approaches to detect chemical composition and mechanical elasticity pathology of cells in cancer development and their medical treatment researches. The application is, however, suffering from the lack of ability to synchronously acquire the scattering signals following three-dimensional (3D) cell morphology with reasonable spatial resolution and signal-to-noise ratio. Herein, we propose a divided-aperture laser differential confocal 3D Geometry-Raman-Brillouin microscopic detection technology, by which reflection, Raman, and Brillouin scattering signals are simultaneously in situ collected in real time with an axial focusing accuracy up to 1 nm, in the height range of 200 µm. The divided aperture improves the anti-noise capability of the system, and the noise influence depth of Raman detection reduces by 35.4%, and the Brillouin extinction ratio increases by 22 dB. A high-precision multichannel microspectroscopic system containing these functions is developed, which is utilized to study gastric cancer tissue. As a result, a 25% reduction of collagen concentration, 42% increase of DNA substances, 17% and 9% decrease in viscosity and elasticity are finely resolved from the 3D mappings. These findings indicate that our system can be a powerful tool to study cancer development new therapies at the sub-cell level.

11.
Heliyon ; 9(4): e15229, 2023 Apr.
Article in English | MEDLINE | ID: mdl-37095936

ABSTRACT

Cadmium-based semiconductors have a wide range of applications in light-emitting, energy conversion, photodetection and artificial photosynthesis. With the concern about the potential toxicity of Cd, it is necessary to recycle the element from the Cd based semiconductors. Commonly, the precipitation of Cd cations with S2- is deemed as the end point of recycling. However, actually, CdS is easy to be oxidized and released into the environment and accumulate in the food chain. It still remains challenges on how to refine the Cd element and convert it to the raw material. Herein, we demonstrate a facile room temperature method for recycling Cd from CdS. Cd can be produced from CdS within 3 h with the help of the lithium-ethylenediamine solution. DFT calculations further confirm that the high surface energy of (100) and (101) planes are selectively attacked by the solvated electrons in the solution, which is in good accordance with the XRD, STEM-HAADF and XPS characterizations. With a total recovery efficiency of 88%, Cd is successfully recovered from the CdS powder. This method provides a new perspective on the treatment of Cd-based semiconductor waste, which is of great significance for the recycling of cadmium metal.

12.
Small ; 19(28): e2300849, 2023 Jul.
Article in English | MEDLINE | ID: mdl-36988005

ABSTRACT

High-concentrated non-flammable electrolytes (HCNFE) in lithium metal batteries prevent thermal runaway accidents, but the microstructure of their solid electrolyte interphase (SEI) remains largely unexplored, due to the lack of direct imaging tools. Herein, cryo-HRTEM is applied to directly visualize the native state of SEI at the atomic scale. In HCNFE, SEI has a uniform laminated crystalline-amorphous structure that can prevent further reaction between the electrolyte and lithium. The inorganic SEI component, Li2 S2 O7 , is precisely identified by cryo-HRTEM. Density functional theory (DFT) calculations demonstrate that the final Li2 S2 O7 phase has suitable natural transmission channels for Li-ion diffusion and excellent ionic conductivity of 1.2 × 10-5 S cm-1 .

13.
Int J Colorectal Dis ; 38(1): 31, 2023 Feb 09.
Article in English | MEDLINE | ID: mdl-36757427

ABSTRACT

AIMS: To evaluate the impact of SARS-CoV-2 vaccine on IBD activity. METHODS: Adult IBD patients from five large IBD centers in China were enrolled and followed up for 6 months. Patients were divided into vaccinated and unvaccinated groups according to vaccination status. Demographic and clinical data were collected. RESULTS: A total of 280 individuals (213 UC and 67 CD patients) were enrolled in the study. The unvaccinated and vaccinated groups of UC patients were comparable for basic characteristics, including age (t = - 0.8, p = 0.425), sex (χ2 = 0.980, p = 0.322), course of disease (z = - 0.513, p = 0.608), surgical conditions (χ2 = 1.042, p = 0.838), disease extent (χ2 = 4.853, p = 0.088), or baseline drug therapy (χ2 = 7.784, p = 0.064). In the subgroup of UC patients, there was no association between vaccination and disease activities, according to the medium disease activity scores for two groups: unvaccinated patients having scores (IQR) 1(2.75), 1(2), 1(2), and 1(2) at baseline, 1, 3, and 6 months, respectively, whereas vaccinated patients having scores (IQR) 1(2), 1(2), 1(2), and 1(2). Similar conclusions were also derived in the subgroup of CD patients. There were also no statistically significant differences in age (t = - 1.48, p = 0.144), sex (χ2 = 0.003, p = 0.957), course of disease (z = - 0.074, p = 0.941), surgical conditions (χ2 = 0.613, p = 0.594), localization (χ2 = 6.261, p = 0.199), or baseline drug therapy (χ2 = 5.881, p = 0.114) between 2 groups of CD patients. The medium disease activity scores (IQR) of the unvaccinated group at baseline, 1, 3, and 6 months were 1(4), 1(3), 1(3), and 1(3), respectively, whereas those of vaccinated group were 2.5(3.75), 2.5(3.75), 3(2), and 2(2), respectively. Overall, very few participants in this study described worsening IBD disease activity requiring a change or addition of medication. CONCLUSIONS: SARS-CoV-2 vaccine has no adverse effect on disease activity in IBD population. IBD patients should be recommended to receive SARS-CoV-2 vaccine in time.


Subject(s)
COVID-19 , Colitis, Ulcerative , Crohn Disease , Inflammatory Bowel Diseases , Adult , Chlorocebus aethiops , Animals , Humans , Crohn Disease/drug therapy , Colitis, Ulcerative/drug therapy , COVID-19 Vaccines/therapeutic use , Vero Cells , COVID-19/prevention & control , SARS-CoV-2 , Inflammatory Bowel Diseases/drug therapy , China/epidemiology
14.
Nat Commun ; 14(1): 146, 2023 Jan 10.
Article in English | MEDLINE | ID: mdl-36627277

ABSTRACT

High-energy Ni-rich layered oxide cathode materials such as LiNi0.8Mn0.1Co0.1O2 (NMC811) suffer from detrimental side reactions and interfacial structural instability when coupled with sulfide solid-state electrolytes in all-solid-state lithium-based batteries. To circumvent this issue, here we propose a gradient coating of the NMC811 particles with lithium oxy-thiophosphate (Li3P1+xO4S4x). Via atomic layer deposition of Li3PO4 and subsequent in situ formation of a gradient Li3P1+xO4S4x coating, a precise and conformal covering for NMC811 particles is obtained. The tailored surface structure and chemistry of NMC811 hinder the structural degradation associated with the layered-to-spinel transformation in the grain boundaries and effectively stabilize the cathode|solid electrolyte interface during cycling. Indeed, when tested in combination with an indium metal negative electrode and a Li10GeP2S12 solid electrolyte, the gradient oxy-thiophosphate-coated NCM811-based positive electrode enables the delivery of a specific discharge capacity of 128 mAh/g after almost 250 cycles at 0.178 mA/cm2 and 25 °C.

15.
Dig Dis Sci ; 68(5): 1864-1872, 2023 05.
Article in English | MEDLINE | ID: mdl-36436157

ABSTRACT

BACKGROUND: 5-Hydroxytryptamine (5-HT) and stem cells marker G-protein-coupled receptor 5 (LGR5) are associate with gastrointestinal inflammation and tumorigenesis. But the relationship between 5-HT and LGR5 is unclear. OBJECTIVE: To explore the expression and correlation of 5-HT and LGR5 in gastric mucosa of patients with gastritis and gastric cancer (GC). METHODS: A total of 41 patients with GC and 98 patients with chronic gastritis were included in this study. The expression of TPH1 mRNA, LGR5 mRNA and ß-catenin mRNA in gastric mucosa were explored by Real-time Quantitative polymerase chain reaction (qPCR). 5-HT-positive cells and LGR5-positive cells in gastric mucosa were detected by immunohistochemistry stains. The co-localization of 5-HT and chromogranin A (CgA), 5-HT receptor4 (5-HTR4) and LGR5 were detected by multiplex immunofluorescence. RESULTS: The expression of 5-HT and LGR5 in patients with GC was significantly higher than patients with chronic gastritis (p < 0.05). The positive rate of 5-HT and LGR5 increased sequentially in the patients with non-atrophic gastritis, intestinal metaplasia and GC, which were 18.52%, 35.56% and 75.61% for 5-HT, and 27.78%, 40.91% and 95.12% for LGR5, respectively. The expression of 5-HT and LGR5 was positively correlated in gastritis and GC patients (p < 0.05). Moreover, the expression level of TPH1 mRNA and LGR5 mRNA was also positively correlated in gastritis patients (r = 0.7377, p < 0.001). Besides, 5-HT was partially co-localized with CgA, and 5-HTR4 was co-localized with LGR5 in gastric mucosa. CONCLUSION: The increase of 5-HT synthesis in gastric mucosa may have an impact on LGR5-positive gastric epithelial stem cells.


Subject(s)
Gastritis, Atrophic , Gastritis , Stomach Neoplasms , Humans , Stomach Neoplasms/genetics , Stomach Neoplasms/metabolism , Serotonin , Gastritis/metabolism , Gastric Mucosa/metabolism , Gastritis, Atrophic/metabolism , Stem Cells/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptors, G-Protein-Coupled/genetics , Receptors, G-Protein-Coupled/metabolism
16.
Nano Lett ; 22(23): 9614-9620, 2022 Dec 14.
Article in English | MEDLINE | ID: mdl-36454039

ABSTRACT

Rechargeable solid-state Na metal batteries (SSNMB) can offer high operational safety and energy density. However, poor solid-solid contact between the electrodes and the electrolyte can dramatically increase interfacial resistance and Na dendrite formation, even at low current rates. Therefore, we developed a carbon-fiber-supported liquid Na-K alloy anode that ensures close anode-electrolyte contact, enabling superior cycle stability and rate capability. We then demonstrated the first cryogenic transmission electron microscopy (cryo-TEM) characterization of an SSNMB, capturing the evolution of solid-electrolyte interphase (SEI) and revealing both crystalline and amorphous phases, which could facilitate ion transport and prevent continuous side reactions. By enhancing contact between the Na-K alloy and solid-state electrolyte, these symmetric cells are capable of cycling for over 800 h without notable increased polarization and enable an unprecedented critical current density (CCD) at 40 mA cm-2. Our liquid Na-K alloy approach offers a promising strategic avenue toward commercial SSNMBs.

17.
Nanoscale ; 14(45): 17036-17043, 2022 Nov 24.
Article in English | MEDLINE | ID: mdl-36367106

ABSTRACT

Inversion symmetry breaking plays a critical role in the formation of magnetic skyrmions. Therefore, for the application of skyrmion-based devices, it is important to develop novel engineering techniques and explore new non-centrosymmetric lattices. In this paper, we report the rational synthesis of stable γ-phase MnS1-xSex (0 ≤ x ≤ 0.45) nanoflakes with an asymmetric distribution of the elemental content, which persists on inversion symmetry breaking. The temperature dependence of resonant second-harmonic generation characterization reveals that a non-centrosymmetric crystal structure exists in our as-grown γ-phase MnS1-xSex with spatial-inversion symmetry breaking. By tuning the parameters of nucleation temperature and growth time, we produced a detailed growth phase diagram, revealing a controllable as-grown structure evolution from γ-phase wurtzite-type to α-phase rock-salt type structure of MnS1-xSex nanoflakes. Our work provides a new playground to explore novel materials that have broken inversion symmetry.

18.
Nano Lett ; 22(11): 4347-4353, 2022 06 08.
Article in English | MEDLINE | ID: mdl-35584238

ABSTRACT

The high specific capacity of alkalic metal (Li, Na, and K) anodes has drawn widespread interest; however, the practical applications of alkalic metal anodes have been hampered by dendrite growth and interfacial instability, resulting in performance deterioration and even safety issues. Here, we describe a simple method for building tunable fluoride-based artificial solid-electrolyte interphase (SEI) from the fluorination reaction of alkali metals with a mild organic fluorinating reagent. Comprehensive characterization by advanced electron microscopes shows that the LiF-based artificial SEI adopts a crystal-glass structure, which enables efficient Li ion transport and improves structural integrity against the volume changes that occur during Li plating/stripping. Compared with bare Li anode, the ones with artificial SEI exhibit decreased voltage hysteresis, enhanced rate capability, and prolonged cycle life. This method is also applied to generate fluoride-based artificial SEI on Na and K metal anodes that brings significant improvement in battery performance.


Subject(s)
Fluorides , Halogenation , Electrodes , Interphase , Lithium/chemistry , Sodium/chemistry
19.
ACS Appl Mater Interfaces ; 14(11): 13883-13890, 2022 Mar 23.
Article in English | MEDLINE | ID: mdl-35274527

ABSTRACT

The half-metallic manganite oxide La2/3Sr1/3MnO3 (LSMO) has a very high spin polarization of ∼100%, making it ideal for ferromagnetic electrodes to realize tunneling magnetoresistance (TMR). Because of the in-plane magnetic anisotropy of the ferromagnetic LSMO electrode, which leads to the density limit of memory, realizing perpendicular tunneling in manganite-based magnetic tunnel junctions (MTJ) is critical for future applications. Here, we design and fabricate manganite-based MTJs composed of alternately stacked cobaltite and manganite layers that demonstrate strong perpendicular magnetic anisotropy (PMA) induced by interfacial coupling. Moreover, spin-dependent tunneling behaviors with an out-of-plane magnetic field were observed in the perpendicular MTJs. We found that the direct tunneling effect plays a dominant role in the low bias region during the transport behavior of devices, which is associated with thermionic emission of electrons or oxygen vacancies in the high bias region. Our works of realizing perpendicular tunneling in manganite-based MTJs lead to new approaches for designing and developing all-oxide spintronic devices.

20.
Biotechnol Biofuels Bioprod ; 15(1): 33, 2022 Mar 25.
Article in English | MEDLINE | ID: mdl-35337369

ABSTRACT

BACKGROUND: Schizochytrium sp. is a marine heterotrophic protist and an important sustainable resource for high value-added docosahexaenoic acid in the future. The production of different phenotypes during the continuous subculture of Schizochytrium sp. results in a serious reduction in lipid yield and complicates the used of this strain in scientific research and industrial production. Hence, obtaining an improved understanding of the phenotypic differences and molecular mechanisms underlying the cell-to-cell heterogeneity of Schizochytrium sp. is necessary. RESULTS: After continuous culture passage, Schizochytrium sp. H016 differentiated into two subpopulations with different morphologies and showed decreased capacity for lipid production. The presence of cell subpopulations with degraded lipid droplets led to a substantial decrease in overall lipid yield. Here, a rapid screening strategy based on fluorescence-activated cell sorting was proposed to classify and isolate subpopulations quickly in accordance with their lipid-producing capability. The final biomass and lipid yield of the subpopulation with high cell lipid content (i.e., H016-H) were 38.83 and 17.22 g/L, respectively, which were 2.07- and 5.38-fold higher than those of the subpopulation with low lipid content (i.e., H016-L), respectively. Subsequently, time­resolved transcriptome analysis was performed to elucidate the mechanism of phenotypic heterogeneity in different subpopulations. Results showed that the expression of genes related to the cell cycle and lipid degradation was significantly upregulated in H016-L, whereas the metabolic pathways related to fatty acid synthesis and glyceride accumulation were remarkably upregulated in H016-H. CONCLUSION: This study innovatively used flow cytometry combined with transcriptome technology to provide new insights into the phenotypic heterogeneity of different cell subpopulations of Schizochytrium sp. Furthermore, these results lay a strong foundation for guiding the breeding of oleaginous microorganisms with high lipid contents.

SELECTION OF CITATIONS
SEARCH DETAIL